United States      Office of Air Quality      EPA-450/2-78-125a
Environmental Protection  Planning and Standards     July 1979
Agency        Research Triangle Park NC 27711  ,/ i t  - ^
Air
Stationary Internal     Draft
Combustion Engines   EIS

Standards Support and
Environmental Impact
Statement  Volume I:
Proposed Standards
of Performance

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                                     DRAFT

                      Standards  Support and Environmental
                             Impact Statement for
                    Stationary Internal  Combustion Engines

                        Type  of  Action:   Administrative

                                Prepared by:
     rector, Emission Standards  and  Engineering  Division                (Date)
  Environmental Protection Agency
  Research Triangle Park, N. C.  27711


                                Approved by:
^Assistant Administrator for A1r, Noise and Radiation
  Environmental Protection Agency
  Washington, D. C.  20460
  Draft Statement Submitted to EPA's
  Office of Federal Activities for Review on
                                                                       (Date)


  Additional copies may be obtained at:


  Environmental Protection Agency Library (MD-35)
  Research Triangle Park, N. C.  27711


  This document may be reviewed at:

  Central Docket Section
  Room 2903B, Waterside Mall
  401  M Street
  Washington, D. C.  20460

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                                    EPA-450/2-78-125a
  Stationary Internal Combustion Engines

Standards Support and Environmental Impact
  Statement Volume  I: Proposed Standards
                  of Performance
                          by


                Emission Standards and Engineering Division
               U.S. ENVIRONMENTAL PROTECTION AGENCY
                  Office of Air, Noise, and Radiation
                Office of Air Quality Planning and Standards
               Research Triangle Park, North Carolina 27711

                        July 1979

                 U.S. Environmental Protection Agency
                 Region V, Library
                 230 South Dearborn Street
                 Chicago, Illinois 60604

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This report has been reviewed by the Emission Standards and
Engineering Division of the Office of Air Quality Planning
and Standards, EPA, 'and approved for publication.  Mention
of trade names or commercial products is not intended to
constitute endorsement or recommendation for use.  Copies
of this report are available through the Library Services
Office (MD-35), U. S. Environmental Protection Agency,
Research Triangle Park,  North Carolina  27711,  or from
National Technical Information Services, 5285 Port Royal
Road,  Springfield, Virginia 22161.
                 PUBLICATION NO.  EPA-450/3-78-125a
            UtS. Environmental  Protection  Agency
                                 11

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                              TABLE OF CONTENTS


Section                                                                Page

            LIST  OF  ILLUSTRATIONS	  .   V111

            LIST  OF  TABLES	   xv

   1         SUMMARY	1-1

   2        INTRODUCTION	2-1

            2.1   Authority for the Standards	2-1
            2.2   Selection of Categories of Stationary Sources   ...   2-4
            2.3   Procedure for Development of Standards of
                 Performance	2-5
            2.4   Consideration of Costs 	   2-8
            2.5   Consideration of Environmental Impacts 	   2-10
            2.6   Impact on Existing Standards 	   2-11
            2.7   Revision of Standards of Performance 	   2-12

   3        THE  STATIONARY RECIPROCATING INTERNAL COMBUSTION
            ENGINE PROCESS AND, INDUSTRY	3-1

            3.1   General	3-1

            3.1.1  Engine Manufacturers	3-2
            3.1.2  Engine Users	3-13

            3.2   Processes  and Their Emissions   	   3-18

            3.2.1  Fundamental Description of 1C Engines  	   3-18
            3.2.2  Emission Sources and Types in 1C  Engines  	   3-29
            3.2.3  State and Local  Regulations   	   3-40

   4         EMISSION CONTROL TECHNIQUES 	   4-1

            4.1   Pollutant Formation	•.  .  .  .   4-3

            4.1.1  Nitrogen Oxides  (NOx)  . .  .	4-3
            4.1.2 Hydrocarbons (HC)	4-5
            4.1.3 Odor	4-6
            4.1.4 Carbon Monoxide  (CO)	4-7
            4.1.5 Smoke and Particulate Matter 	   4-7
            4.1.6 Sulfur Dioxide (S02) 	   4-9

            4.2   Factors  that Affect Reported NOx Emission
                 Levels	4-10

            4.2.1 Effect of Ambient Humidity,  Temperature,  and
                  Pressure	   4-11
            4.2.2 Effect of Measurement Practices  	   4-30

            4.3   Uncontrolled Emission Levels 	   4-36

                                      iii

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                        TABLE OF CONTENTS (Continued)


Section                                                                Page

            4,3.1   Existing Data Base	4-37
            4.3.2   Uncontrolled Emission Levels 	   4-39
            4.3.3   Effect of Engine Variability on NOx
                   Emissions	4-52
            4.3.4   Sales-Weighted Uncontrolled Emissions  	   4-68

            4.4 NOx Emission Reduction Techniques  	   4-73

            4.4.1   Derating	4-80
            4.4.2   Retarded Ignition Timing 	   4-88
            4.4.3   A1r-to-Fuel  Ratio Changes  	   4-95
            4.4.4   Turbocharglng	4-102
            4.4.5   Reduced Manifold A1r Temperature 	   4-107
            4.4.6   Exhaust Gas  Recirculatlon  	   4-112
            4.4.7   Water Induction	4-121
            4.4.8   Combustion Chamber Geometries  	   4-126
            4.4.9   Catalytic Converters 	   4-137
            4.4.10  Combinations of Controls  	   4-140
            4.4.11  Summary of NOx Reductions 	   4-145
            4.4.12  Effects of NOx Controls on HC, CO and Smoke .  .  .   4-160
            4.4.13  Combustion of Nonstandard Fuels 	   4-171

            4.5  Emission Reduction Techniques Primarily
                 for HC and CO	4-176

            4.5.1   Modifications to Air and Fuel Handling
                   Systems	4-177
            4.5.2   Combustion Chamber Modifications 	   4-181
            4.5.3   Exhaust Treatment  	   4-184

            4.6  Smoke	4-191

   5        MODIFICATIONS AND RECONSTRUCTIONS 	   5-1

            5.1  Background	5-1
            5.2  Modifications	' . .  .  .   5-3

            5.2.1   General	,	5-3
            5.2.2  Physical Changes 	   5-3
            5.2.3  Operating Changes  	   5-6

            5.3  Reconstruction	5-7
            5.4  Summary	5-9
                                     Iv

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                        TABLE OF CONTENTS (Continued)


Section

   6        ALTERNATIVE EMISSION CONTROL TECHNIQUES 	   6-1

            6.1  Review of Candidate NOx Control Techniques 	   6-1
            6.2  Emission Reductions and Fuel Penalties for
                 Candidate NOx Control  Techniques 	   6-7
            6.3  Estimated Time to Implement NOx Control
                 Techniques	6-12

   7        ENVIRONMENTAL IMPACT  	   7-1

            7.1  Air Pollution Impact	7-1

            7.1.1  Model Plant Characteristics  	   7-2
            7.1.2  The Dispersion Model and Meteorological
                   Considerations 	   7-3
            7.1.3  Results and Discussion of Dispersion
                   Calculations 	   7-6
            7.1.4  NOx Concentrations	7-11
            7.1.5  CO and HC Concentrations	7-12
            7.1.6  SOx Concentrations	7-13
            7.1.7  Particulates	7-14

            7.2  Water Pollution Impact  	   7-14
            7.3  Solid Waste Disposal Impact  	   7-16
            7.4  Energy  Impact	7-16
            7.5  Other Environmental Impacts  	   7-19

            7.5.1  Noise Impact	7-19
            7.5.2  Thermal Pollution Impact  	   7-19

            7.6  Other Environmental Concerns 	   7-20

            7.6.1  Irreversible and  Irretrievable Commitment
                   of Resources	7-20
            7.6.2  Environmental Impact  of Delayed Standards   ....   7-20
            7.6.3  Environmental Impact  of No Standard   	   7-21

    8        ECONOMIC IMPACT  	   8-1

            8.1  Industry  Profile  	  8-1

            8.1.1  Structure of the  Industry	8-2
            8.1.2  Large-Bore  Engine Manufacturers	8-15
            8.1.3  Stationary  Markets  for Large-Bore  Reciprocating
                   Engines	8-20
            8.1.4  Balance-of-Trade  	  8-35

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                        TABLE OF CONTENTS (Continued)

Section

            8.2  Cost Analysis for Control of NOX Emissions .....  8-
                                                              39
 8.2.1   Now  Engines   ...................   3_3g
 8.2.2   Engine  Manufacturers  ..........  '.'.'.'.'.   8-57
 8.2.3   Emerging  Controls   ...........  ..'.,.   8-61
 8.2.4   Fuel  Pretreatment   ...........  .  .  .  .     8-67
 8.2.5   Modified  Facilities   ..........  !.".'!"   8-70
 8.2.6   Reconstructed  Facilities  .........  .  .  .  .   8-73

 8.3  Other  Cost  Considerations   .............   8-74

 8.4  Economic  Impact  of Alternative  Emission
     Control Techniques .................   8-76

 8.4.1   Impact  on Manufacturers   .............   8-79
 8.4.2   Impact  on Product Prices  .........  .  .  .  '.   8-99
 8.4.3   Impact  on Employment  .............    '   8-108
 8.4.4   Impact  on Foreign Trade   .  .' .......  !  !  !  !   8-108
 8.4.5   Summary of Economic Impact  Analysis  .....  .  .   8-110

 RATIONALE TO REGULATE NOX EMISSIONS  FROM LARGE-BORE
 STATIONARY  RECIPROCATING INTERNAL  COMBUSTION
 ENGINES  .........................   9_-j

 9.1  Selection of Stationary Reciprocating 1C Engines
     for new Source Performance  Standards ........   9-1

 9.2  Selection of Pollutants  ..............  9_8

 9.3  Selection of Affected Facilities ..........  9-11

 9.4  Selection of Best System of Emission Reduction  .  .  .  9-34

 9.5  Selection of Format for the Standards  .......  9-59

 9.6  Selection of Numerical Emission Limits .......  9-65

 9.7  Selection of Compliance Time Frame  ........   9-82

 9.8  Selection of Long-Term Emission Limits  ......   9-84

9.9  Modification/Reconstruction ............   9-84

9.10 Selection of Performance Test Method  .......   9-85

9.11  Selection of Monitoring Requirements  .......   9-86
                         VI

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                        TABLE OF CONTENTS (Concluded)

Section                                                                 £afl£

APPENDIX A -- EVOLUTION OF PROPOSED STANDARDS  	   A-l

APPENDIX B -- INDEX OF ENVIRONMENTAL IMPACT CONSIDERATIONS 	   B-l

APPENDIX C -- EMISSION SOURCE TEST DATA	   C-l

         C.I  Data	   C-l
         C.2  Review of Ambient Correction Factors for
              Application to Large-Bore Engine NOX Data  	   C-88
         C.3  Review of NOX Measurement Methods  	   C-l24
         C.4  The Effect of NOX Control Techniques on
              Nonmethane Hydrocarbon Emissions	   C-l56
         C.5  Development of Conversion BSNOX to NOX (ppm)
              Corrected to 15 Percent 0?	   C-l 73
         C,6  Statistical Analysis for Alternative
              Emission Limits  	   C-184
         C.7  Comparison of Small Bore, Auto Engine Emission
              Control Techniques for Large-Bore Stationary
              1C Engines	 .  .   C-190
         C.8  Determination of Sales-Weighted Average Uncontrolled
              CO and HC Etntsstons  ,,,.,..,,...<•••«   C-l 96


GLOSSARY
                                      vti

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                           LIST OF  ILLUSTRATIONS


Figure                                                              Page

3-1      Manufacturers categorized  by engine horsepower   ....    3-6

3-2      Manufacturers categorized  by engine horsepower
         per cylinder	    3-7

3-3      Manufacturers of medium and large engines,
         categorized by cylinder displacement,  in3/cyl   ...      3-8

3-4      Manufacturers of medium and large engines
         categorized by bore size,  inches  	    3-9

3-5a     Potential users of stationary reciprocating
         engines:  irrigated farms  	    3-19

3-5b     Major natural gas pipelines 	    3-21

3-6      The four-stroke, spark-ignition (SI) cycle.  Four
         strokes of 180° of crankshaft rotation each, or 72Q°
         of crankshaft rotation per cycle  	    3-25

3-7      Cylinder events for a two-stroke blower-scavenged
         1C engine	    3-28

3-8      Effect of A/F ratio on emissions from a
         gasoline engine 	    3-33

4-1      1969 humidity range in engine test cells,
         Dearborn, Michigan  	    4-14

4-2      Effect of ambient humidity on NOx emissions
         for 1C engines	    4-15

4-3      Effect of ambient temperature on NOx emission
         levels from 1C engines	    4-16

4-4      Effect of humidity on emissions scatter for
         six HD gasoline engines	    4-18

4-5      Effect of humidity and temperature on emissions
         scatter for six HD diesel engines	    4-19

4-6      Comparison of SI ambient humidity correction
         factors	    4-22

4-7      Effect of manifold air temperature on a
         large-bore 4-TC engine  	    4-24
                                   viii

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LIST OF ILLUSTRATIONS (Continued)
Figure
4-8
4-10
4-11
4-12
4-13a
4-13b
4-13c
4-14a
4-14b
4-14c
4-15a
4-15b
4-15c
4-16a
4-16b
4-16c
4-17
4-18
4-19
4-20
A 91
Test results of NOx emissions versus Intake air
temperature for two blower-scavenged
Correction factors for temperature for CI engines . . .
Measurement uncertainty relative to EPA procedure . . .
Uncontrolled NOx emissions from dlesel engines ....
Uncontrolled NOx emissions from dual-fuel engines . . .

Uncontrolled CO emissions from dual-fuel engines . . .

Uncontrolled HC emissions from dual-fuel engines . . .
Uncontrolled NOx levels versus brake specific fuel
Uncontrolled NOx levels versus brake specific fuel
Uncontrolled NOx level versus brake specific fuel
NOx production variation with number of cylinders . . .
Variation in NOx level with number of cylinders for
individual engine models of different manufacturers . .


rgtje
4-25
4-28
4-33
4-34
4-40
4-41
4-42
4-43
4-44
4-45
4-46
4-47
4-48
4-49
4-50
4-51
4-61
4-62
4-64
4-65
4-67
               IX

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                     LIST OF ILLUSTRATIONS (Continued)




Figure

4-22a
4-22b
4-22c

4-23
4-24
4-25a
4-25b
4-25c
4-26

4-27
4-28

4-29

4-30

4-31

4-32

4-33
4-34

Sales-weighted uncontrolled NOx emissions for
diesel engines ...
Sales-weighted uncontrolled NOx emissions for
dual-fuel engines ....
Sales-weighted uncontrolled NOx emissions for
gas engines 	
NOx emissions versus torque at constant speed
Effect of derate on NOx emissions .
Effect of different amounts of derate on NOx
emissions and fuel consumption from diesel engines.
Effect of different amounts of derate on NOx
emissions and fuel consumption on dual-fuel engines .
Effect of different amounts of derate on NOx
emissions and fuel consumption for gas engines
Effect of retard on NOx emissions and
fuel consumption ....
«nH6J,«?f d1ffer!?t amounts of ^tard on NOx emissions
and fuel consumption for diesel engines
»nrfef».?f d1fferj!?t ™ounts of retard ^ NOx emissions
and fuel consumption for gas and dual-fuel
engines 	
Effect of A/F ratio on emissions of a
gasoline engine ....
Effect of A/F on NOx emissions and fuel
consumption ....
Effect of A/F changes on NOx emissions and
fuel consumption ....

Schematic of turbocharged intercooled
large-bore engine 	
Effect of turbocharging on NOx emissions
Effect ^ of manifold air temperature reduction on
NOx emissions and fuel consumption . .
Page
4-69
4-70

4-71
4-81
4-83
4-84
4-85
4-86

4-90
4-92

4-93

4-96

4-99
41 f\f\
-100

4-103
4-105
4-110

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LIST OF ILLUSTRATIONS (Continued)
Figure
4-35


4-36

4-37


4-38

4-39

4-40
4-41

4-42

4-43

4-44a

4-44b

4-45

4-46a

4-46b

4-47

4-48a


Effect of different amounts of manifold air
temperature reduction on NOx emissions and fuel
consumption 	
Effect of exhaust gas recirculation on NOx
emissions and fuel consumption 	 	
Effects of different amounts of EGR on NOx and
fuel consumption for gas, dual-fuel, and diesel
engines 	
Simplified schematic of EGR system for turbocharged
intercooled engine 	
Effect of water induction on NOx emissions and fuel
consumption 	 .
Effect of water induction rate on NOx emissions ....
Water induction versus NOx emission for a turbocharged
engine at 2200 rpm 	
Schematic of a current production precombustion chamber
for a diesel engine 	
Schematic of an "M-system" piston for a diesel
engine 	 	 	
Schematic of a current production stratified charge
gasoline engine 	
Schematic of a prototype stratified charge gasoline
engine 	
Diagram of "squish-lip" and standard combustion
chamber geometries for medium-bore diesel engine . . .
NOx emissions from four-stroke diesel engines with
modified combustion chambers 	
HC and CO emissions from four-stroke diesel engines
with modified combustion chambers 	
Possible location of a catalytic muffler on a large-
bore engine 	
Additive effects of controls for a large-bore diesel
engine 	 	 	
Page


4-111

4-116


4-118

4-119

4-122
4-124

4-125

4-128

4-129

4-130

4-131

4-133

4-134

4-135

4-138

4-141
              xi

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                      LIST OF  ILLUSTRATIONS  (Continued)
 4-48b    Additive effects of controls for a large-bore dual-
          fuel engine ......................    4-142

 4-48c    Additive effects of controls for larqe-bore aas
          en91nes .............. : . . . I .....    4-143

 4-49a    Summary of NOx reductions achieved by dlesel
          en9es ........................     4_161

 4-52b     HC levels  versus  controlled NOx levels  for dual-fuel
          engines ........................     4_162

 4-52c     HC levels  versus  controlled NOx levels  for qas
          er)9ines .................. ......    4-163

4-53a    CO emissions versus controlled NOx level for diesel
         en9ines ........................    4-166

4-53b    CO emissions versus controlled NOx level for dual-
         fuel  engines  .....................    4_167

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                     LIST OF ILLUSTRATIONS (Continued)


Figure

4-53c    CO emissions versus controlled NOx levels for gas
         engines ........................    4-168

4-54     Smoke levels versus NOx levels for large-bore diesel
         engines ........................    4-170

4-55     Schematic illustrations of standard production spray
         tip and the low sac volume spray tip   .........
4-56     Exhaust smoke reduction schedule for HMD Model 645
         Roots blown locomotive engines (164) at rated conditions
         (Ringelmann 1 = 20% opacity, NO. 2 = 40%, etc.)  ....    4-187

4-57     Exhaust smoke reduction schedule for EMD Model 645
         turbocharged locomotive engines  (165)  (Ringelmann
         1  = 20%, opacity, No. 2 = 40%, etc.)   .........    4-188

8-1      Annual production of  gasoline engines  (excluding
         automotive, outboard, and aircraft engines)   ......   8-12

8-2      Annual production of  diesel  engines  (excluding
         automotive, outboard, and aircraft engines)   ......   8-13

8-3      Annual production of  gas engines  (excluding  automotive,
         outboard,  and  aircraft engines)  ............    8-14

8-4      Sales  of  large-bore  (>350 CID/cyl) diesel  horsepower
          (from  References  16  to 21)   ..............    8-23

8-5      Chart  shows  relative cost  data  and most favorable
         operating  ranges  for the  various types of  generating
         facilities,  as  derived from one  particular study (from
         References 23  —  costs for  1968)  ...........     8-26

8-6       Sales  of  dual-fuel  horsepower during the past 5 years
          (from  References  31-34)  ................     8-29

 8-7       Sales  of  gas  engine  horsepower  by application for the
          past 5 years  (absolute  levels shown  for domestic
          applications,  from References 37-42)  .........     8-30

 8-8      Size distribution of gas engines sold during the past
          5 years ........................     8'32

 8-9      New and added compressor capacity on gas transmission
          pipelines (Reference 43)  ...............     8-33
                                    xi ii

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                       LIST OF  ILLUSTRATIONS  (Continued)


  Figure
  — * —                                                                 Page

  8-10    Relation of initial maintenance and fuel costs to
         total costs for major applications of large-bore
                 ................. ........      8-46
 8"12                                       turMnes
 8-13    Internal combustion engines versus turbines in oil  and gas
         production applications ................ _

 9-1     Distribution of stationary NOx emissions for the'year 1974
         ^Reference 4)
                                                                        9-1 3
 9-3     Manufacturers  of diesel  engines  categorized  by  horse-

         P°Wer .............  •  ............      9-15

 9-4     Manufacturers  of diesel  engines  categorized  by  cubic-inch
         displacement per cylinder  .......... ......      g_16

 9-5     Displacement per cylinder  versus continuous  rated horse-
         power for diesel  engines   ................      9_20

 9-6     Sales of dual -fuel horsepower during the' past 5 years
         (from References  19 to 22)  ..........  .     . .      9-22

 9-7     Manufacturers of  dual-fuel engines categorized by horse-
         P°Wer ..........................      9-23

 9-8     Manufacturers of dual-fuel engines categorized by cubic-
         inch displacement per cylinder  .............      9.34

 9-9      Sales of gas engine horsepower by application for the
         last 5 years (absolute levels  shown for domestic appli-
         cations from References 24 to  29)                              9_26

9-10    Size distribution of gas  engines  sold during  the past
        o years ........  ,
9-11    Manufacturers of gasoline and natural  gas engines  cate-
        gorized by horsepower ...........  .  ......       9_2g
                                    xiv

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                     LIST OF ILLUSTRATIONS (Continued)


Figure                                                                 E§3i

9-12    Manufacturers of gasoline and natural gas engines cate-
        gorized by cubic-inch displacement per cylinder 	     9-32

9-13    Effect of different amounts of retard on NOx emissions and
        fuel consumption for diesel engines 	     9-42

9-14    Effect of A/F changes on NOx emissions and fuel consump-
        tion  	     9"43

9-15    The effect of air-to-fuel ratio change on CO emissions from
        naturally aspirated gas engines 	     9-50

9-16    Statistical effects of alternative emission limits on gas
        engines	     9-79

9-17    BSNOx converted to N0x15 and best fit straight line
        determined	    9-84

9-18    Variation in conversion of fuel-bound nitrogen to organic
        NOx in a gas turbine	    9-89
                                       xv

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LIST OF TABLES
Table

3-1
3-2
3-3

4-1
4-2

4-3

4-4

4-5
4-6

4-7

4-8

4-9
4-10

4-11

4-12a

4-12b

4-12c



1C Engine Manufacturers 	
Stationary Engine Applications 	
Factors That Affect Emissions from Reciprocating
Engines 	
Ambient Humidity Correction Factors for SI Engines .
Existing 1C Engine Ambient Correction Factors for
Application to Large-Bore Engines . . .
Large-Bore Engine Manufacturers Measurement
Practices 	
Sources of Error for DEMA, SAE, EMD Emission
Practices 	
Extent of Existing Data Base ....
Sources of Data Variability for Uncontrolled NOx
Emissions from Large-Bore Engines . . .
Variations in NOx Emissions from GMC/EMD
Production Engines 	
Potential Scatter in NOx Emissions from Production
Engines Due to Ambient Humidity and Temperature
Variations 	
Variation in NOx (g/hp-hr) Due to Model Differences . .
Weighted Measurement Uncertainties for Sales
Weighted NOx Levels 	
Abbreviations for Engine Type and Emission
Control Technology 	
Effects of Controls on Engines Larger than 350 In3/
Cyl: NOx Emissions 	
Effects of Controls on Engines Larger than 350 In3/
Cyl: CO Emissions 	
Effects of Controls on Engines Larger than 350 In3/
Cyl: HC Emissions 	
f^
Page
3-3
3-14

3-37
4-21

4-29

4-32

4-35
4-38

4-53

4-56

4-57
4-59

4-72

4-76

4-77

4-78

4-79
   xvi

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LIST OF  TABLES  (Continued)
Table
4-13

4-14
4-15

4-16

4-17
4-18

6-1

6-2

6-3

6-4

6-5


7-1

7-2


7-3
7-4

7-5


Summary of Lowest NOx Levels (g/hr-hr) From
Controlled Large-Bore Engines 	 . 	
NOx Emissions from Various Groupings of Engines ....
Alternative Control Techniques — Summary of
Selected Controls 	
Relationship between Smoke, EGR, Retard, and
Engine Size . 	
Emissions from Engines Burning Sewage Dlgestor Gas. . .
Selected Approximate Properties of Crude 011s
Currently Generating U.S. Residual Oil Supply 	
Summary of NOx Emission Control Techniques for
Reciprocating 1C Engines 	
NOx Reduction and Fuel Consumption Penalties for
Diesel, Dual-Fuel, and Gas Engines 	
Ranges of NOx Reduction Achieved by Various
Control Techniques 	
NOx Control Techniques that Achieve Specific
Levels of NOx Reduction 	
Estimated Time Span Between Decision to Control and
Start of Production of First Controlled Engine
(in months) 	
Emission Source Characteristics of Model Stationary
Internal Combustion Engine Installations 	
Estimated Ground Level Concentrations (at 0.3 km
from Source) Due to Emissions from Stationary
Internal Combustion Engines .... 	
National Ambient Air Quality Standards 	
Estimated Annual Energy Impact of Large-Bore
Engines 	
Estimated Annual Impact of NO Standard on
U.S. NOx Emissions 	
Page

4-153
4-154

4-156

4-172
4-174

4-175

6-2

6-8

6-10

6-11


6-14

7-4


7-7
7-10

1-11

7-22
           xvn

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                           LIST OF TABLES (Continued)
  Table
                                                                      Page
  8-1      U.S. Manufacturers of 1C Engines for
           Stationary Applications ....                            Q •>
                                           •  ••••• ......    a-j

  8-2      Stationary Engines Manufactured in the United States.  .    8-6


                                                 °f Fuei >n<
                                                   ••••«..,    o-Il
  8-4      Manufacturers  of  High-Power  Engines  .......... .   8_16

  8-5      Parent  Corporation Data ................    8_18

  8-6      Planned Construction  of Nuclear Reactors   .......     s-27

  8-7      import  and  Export  of  1C  Engine  Categories  That
           Include Stationary Applications .  .  ..........     8-37

  8-8      Baseline Cost Parameters for Large-Bore Engines  ....     8-45

  8-9       Cost Increases to  the Engine User Resulting
           from NOx Control   .......           a                 0  .0
                                          ...... • .....     O-HO
                                                                     e.49
 8-12     Cost of Alternative NOx Controls for Dual-Fuel
          Engines for Electrical  Generation ...........     8-52

 8-13     Cost of Alternative NOx Controls for Natural  Gas
          Engines for Oil  and Gas Transport ...........     8-53

 8-14     Cost of Alternative NOx Controls for Natural  Gas
          Engines for Oil  and Gas Production   ..........     8-54

 8-15     Summary of  Large-Bore Engine NOx Control Cost
          Penalties (As a  Percentage of Uncontrolled Tests)
          by End  Use   ......................     8-55

 8-16      Range of Cost Penalties  (As a Percentage of
          Uncontrolled Costs) for Manufacturers Average
          Models   .................. ......     8-56

8-17      Estimated Costs for Engine Manufacturers to
          Develop NOx Controls (Based on References 60, 61)  ...     8-59

8-18     Summary of Economic Impacts ..............    8-77


                                   xviii

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LIST OF TABLES (Continued)
Table
8-19

8-20

8-21
8-22

8-23

8-24

8-25

8-26

8-27

8-28

8-29

8-30

8-31

9-1

9-2

9-3


The Cumulative Number of Models Currently
Achieving Various Alternative Standards 	
Estimated Capital Budget Requirements to Meet NOx
Standards of Performance 	
Financial Resources 	
Turbine Versus Reciprocating Internal Combustion
Engines Breakeven Analysis 	
Methodology for Calculating the Breakeven Curves
for Figures 8-10, 8-11, and 8-12 	
Maximum Inflationary Impact on Local
Electricity Prices . . 	
Historical Perspective on Annual Increases in
Electricity Prices 	
Maximum Inflationary Impact on the National
Electric Bill With Full Phase-In 	
Inflationary Impact on the National Electric Bill,
After Five Years 	
Inflationary Impact on Delivered Gas Prices,
After Full Phase-In 	
Inflationary Impact on Delivered Gas Prices,
After Five Years ... 	
Costs of Various Alternative Standards in the
Fifth Year (in Million Dollars) 	
Additional Fuel Needs in the Fifth Year
(Million Barrels) 	 . 	
Nationwide Emissions from Installed 1C Engines
(Percent of Total Emitted in U.S. Each Year) ....
Emissions Factors for Inventory on Table 1*
g/hp-hr (Reference 6) 	 . 	
Emissions from 1C Engines by Size and
Annual Production 	
Page

8-80

8-82
8-84

8-93

8-96

8-103

8-103

8-104

8-105

8-105

8-106

8-107

8-109

9-3

9-4

9-6
          xix

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                          LIST OF  TABLES  (Concluded)


 Table
 -
 9-4       Comparison  of Waukesha,  White Superior,  and
          Medium-Sized Engine  Models Greater  than
          500 Horsepower
9-5      Comparison of  large Caterpillar Gas  Engines with
         Waukesha Gas Engines >350 CID/CYL  .  . !  ........    9.34

9-6      Environmental  Impacts of Alternatives .........    9.55

9-7      Energy Impacts of Alternatives  ............    9.57

9-8      Economic Impacts of Alternatives   ...........    9.55

9-9      Summary of Statistical  Analyses of Alternate
         Emission Limits « Gas  Engines  ............    g_8i

9-10     Numerical NO  Concentration Emission Limits for
         Large Stationary Reciprocating Internal
         Combustion Engines  ..................    9_85

9-11     Existing Internal  Combustion Engine Ambient Correction
         Factors for Application  to  Large-Bore Engines  .....    g-87
                                   xx

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                            1 .   SUMMARY

1.1  PROPOSED STANDARDS
     Standards of performance for stationary internal  combustion en-
gines are being proposed under Section 111  of the Clean Air Act.  These
standards would limit emissions of nitrogen oxides from diesel  and
dual-fuel stationary internal  combustion engines with  greater than 560
cubic inch displacement per cylinder (CID/cyl) and gas engines  with
greater than 350 cubic inch displacement per cylinder  or equal  to or
greater than 8 cylinders and greater than 240 cubic inch displacement
per cylinder.
     The numerical emission limits for N0¥  would be 0.0700 percent by
                                         A
volume (700 ppm) for gas engines, 0.0600 percent by volume (600 ppm)
for diesel engines, and 0.0600 percent by volume (600  ppm) for dual-
fuel engines corrected to 15 percent oxygen on a dry basis and  referenced
to standard atmospheric conditions of 29.92 inches mercury, 85  degrees
Fahrenheit, and 75 grains moisture per pound of dry air.  The proposed
standards would also include an adjustment  factor for  engine efficiency
which would adjust the emissions limits upward linearly for 1C  engines
with thermal efficiencies greater than 35 percent.  NOX emissions from
stationary internal combustion engines, therefore, would be limited
according to one of the following equations:
               STD * 700 /i-il kJ/w-hr\for any gas eng1ne
               STD * 600 pJl kJ/w-hrfor an  d1esel or duai_fuei
                         \Y
                     engine
where:

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                STD • allowable NOX emissions (parts per million
                      volume corrected to 15 percent oxygen on a
                      dry basis).

                  Y • manufacturer's rated  brake-specific fuel
                      consumption  at peak load  (Mlojoules  per
                      watt hour) or owner/operator's brake-
                      specific  fuel  consumption at peak  load  as
                      determined 1n the field.

 During performance tests to determine compliance  with the  proposed

 standards,  measured NOX  emissions  at 15  percent oxygen  would be ad-

 justed to  standard atmospheric conditions  by the  appropriate correction

 factor 1n  the  table below:
Fuel
Diesel and
Dual-Fuel
Gas
Correction Factor
K = 1/(1 + 0.00235(H - 75) + 0.00220 (T - 85))
K B (KH) (KT)
KH = 0.844 + 0.151 (yjjjj) H- 0.075 (^)2
KT * 1 - (T - 85)(0.0135)
where:

          H * observed humidity, grains H20/lb dry air

          T = observed Inlet air temperature, °F



     Internal combustion engine manufacturers,  owners,  or operators may

also elect to develop custom ambient condition correction factors,  1n

terms of ambient temperature,  and/or humidity,  and/or ambient pressure.
                                 1-2

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 These  factors  must also be  substantiated  with data and approved for use
 by EPA.
     The  proposed  standards  would  apply to facilities that commence
 construction 30  months  after the date of  publication in the FEDERAL
 REGISTER.
     Emergency-standby  internal combustion engines and all  one- and
 two-cylinder gas engines  would  be  exempt  from the  NOV emission, limit.
                                                     "         \
 1.2  ENVIRONMENTAL/ECONOMIC  IMPACT
     Four emission  control techniques,  or combinations of these tech-
 niques, have been  identified  as demonstrated  NOX emission reduction
 systems for stationary  internal combustion engines.   These  techniques
 are:   (1) retarded  ignition  or  fuel  injection,  (2)  air-to-fuel  ratio
 changes,  (3) manifold air cooling, and  (4)  derating  power output  (at
 constant speed).   In general, all  four  techniques  are applied  by  chang-
 ing an engine operating adjustment.
     Fuel injection retard is the  most  effective NOX  control technique
 for diesel engines.  Similarly, air-to-fuel ratio  change  is  the most
 effective NOX control technique for  gas engines.   Both  retard  and air-
 to-fuel ratio changes are effective  in  reducing NOY emissions  from
                                                  7\
dual-fuel engines.
     Due to technical considerations, ignition retard  in  excess of
eight degrees in diesel  engines and  changes in the air-to-fuel  ratio in
excess  of five percent in gas engines are  the limits  to which  these
techniques could be realistically applied.  Eight degrees of ignition
retard  in diesel  engines and a five  percent change in air-to-fuel
ratios  in gas engines yield about a 40 percent reduction  in NOV emis-
                                                              A
                                 1-3

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slons.  Actual emissions varied among engine types; however, the
degree of reduction was consistent.
     Consequently, a 40 percent reduction 1n NOX emissions was the most
stringent regulatory option which could be selected as a basis for the
standards.  An alternative of 20 percent NOX emission reduction was
also considered a viable regulatory option which could serve as the
basis for standards of performance.
     The main environmental benefit of a standard based on either al-
ternative would be a reduction 1n national NOV emissions,  which 1s now
                                             A
14.6 million megagrams per year for all stationary sources.  Total NOV
                                                                     X
emissions would decline by 72,500 megagrams annually for alternative I
(20 percent reduction) and 145,000 megagrams annually for alternative
II (40 percent reduction) 1n the fifth year after the standard went
Into effect.
     Ambient air quality dispersion modeling based on "worst case"
conditions Indicates uncontrolled ambient air NOX levels near large
stationary 1C engines can vary from approximately 60 percent of the
National Ambient A1r Quality Standard (NAAQS) of 100 >ug/m3 to over
twice the standard depending on the size of the engine.  Thus,  stan-
dards of performance based on alternative II would be more effective 1n
reducing ambient air NOX levels than standards of performance based on
alternative I.
     Emissions of CO and HC,  however, would Increase, particularly from
naturally aspirated gas engines.   The magnitude of the increase would
be large for CO; however, for both HC and CO, significant emission
reductions are readily achievable in other source categories.  NOV
                                                                 X
                                 1-4

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 emissions, on the other hand, are difficult to reduce, and stationary
 Internal combustion engines offer one of few opportunities for signi-
 ficant NOX reduction.   Therefore, NOX emissions were selected for
 control by standards of performance.
      There would be essentially no water pollution,  solid waste,  or
 noise Impact of standards of performance based on either alternative I
 or alternative II.
      The potential  energy Impact of standards  of performance  based on
 either alternative  1s  small.   The potential  energy Impact 1n  the  fifth
 year after the standards  go Into effect,  based on alternative I,  would
 be equivalent to an Increase  1n fuel  consumption  of  approximately 1.0
 million barrels  of  oil  per  year compared  to  the 1C engine fuel  consump-
 tion of engines  affected  by the standards of 31 million  barrels per
 year.   The potential energy Impact  1n  the fifth year after  the  standard
 goes Into  effect, based on  alternative  II, would  be  equivalent  to
 approximately 1.5 million barrels of oil per year.   The  Impact of
 alternative  II represents only  0.02 percent  of the 1977  domestic  con-
 sumption of  crude oil and natural gas and only 0.02  percent of the
 projected  total  U.S. oil  Imports  five years  after  the  standards go  Into
 effect.
     Economic  Impacts on manufacturers or users of stationary Internal
 combustion engines are small.  Manufacturers of stationary Internal
 combustion engines would Incur additional costs as a result of stan-
dards of performance.  The manufacturers' total capital Investment
requirements for developmental testing of engine models 1s estimated to
be about $4.5 million to comply with standards  of performance based on
                                 1-5

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alternative I and about $5 million to comply with standards of perfor-
mance based on alternative II.  Analyses of the financial statements
and other public financial Information of engine manufacturers Indicate
that the manufacturers' overhead budgets are sufficient to support the
development of these controls without adverse Impact on their financial
position.  Manufacturers would not experience significant differential
cost Impacts among competing engine model families.  Based on "worst-
case" assumptions,  the maximum 1ntra-1ndustry sales losses would be
about six percent as a result of standards of performance based on
either alternative.  In addition, the impact with regard to Increasing
sales of gas turbines would be minimal,  as a ra»ult of standards of
performance based on either alternative.
     The application of NOX controls will also increase costs to the
engine user.  The magnitude of this increase will depend on the amount
and type of emission control applied.  Fuel penalties are the major
factor affecting this increase.
     A two percent increase 1n price would be expected on the average
as the result of standards of performance based on either alternative.
The total additional capital cost for all users would equal  about $9.6
million on a cumulative basis over the first five years to comply with
standards of performance based on either alternative.  Total  uncontrolled
annualized costs of about $580 million by all large stationary 1C
engine users would increase, due mainly to fuel penalties,  by about $25
million to comply with standards of performance based on alternative I
and would increase by about $32 million to comply with standards of
performance based on alternative II in the fifth year after the stan-
                                 1-6

-------
dards go Into effect.
     These Impacts translate Into price Increases for the end products
or services provided by the Industrial and commercial users of large
stationary 1C engines.  The electric utility industry would pass on a
price Increase after five years of 0.02 percent to comply with standards
of performance based on either alternative.  After five years, delivered
natural gas prices would increase 0.02 percent as a result of standards
of performance based on alternative I and 0.04 percent as a result of
standards of performance based on alternative II.  Even after a full
phase-in period of 30 years, during which new controlled engines would
replace all existing uncontrolled engines, these Increases would be 0.1
percent for electric utilities, and 0.1 and 0.3 percent for delivered
natural gas prices as a result of standards of performance based on
alternatives I and II, respectively.
     Based on this assessment of the  Impacts of each alternative, and
since alternative II achieves a greater degree of NOX reduction, it 1s
selected as the best technological system of continuous emission
reduction of N0¥ from stationary large-bore 1C engines, considering the
               /\
cost of achieving such emission reduction, any nonair quality health
and environmental impact, and energy  requirements.
1.3  INFLATIONARY IMPACT
     An economic  impact analysis would have to be developed  if  the
proposed standard caused an increase  in the fifth-year annual1zed cost
of more than $100 million,  a major product price  increase  of  five per-
cent, or an  increase  in national energy consumption  of 25,000 barrels
of oil per day.  The  proposed standard of  performance would  increase
                                  1-7

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operating costs $26 million 1n the fifth year, the largest price In-
creases would be approximately two percent, and energy consumption
would Increase 4,300 barrels of oil per day.  The Agency, therefore,
feels that no economic Impact analysis 1s required,
                                1-8

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                                 CHAPTER 2
                                 INTRODUCTION

       Standards of performance  are proposed following a  detailed
investigation of air pollution control methods available  to  the  affected
industry and the impact of their costs on the industry.   This  document
summarizes the information obtained from such a study.  Its  purpose  is  to
explain in detail the background and basis of the proposed standards  and
to facilitate analysis of the proposed standards by  interested persons,
including those who may not be familiar with the many technical  aspects of
the industry.  To obtain additional copies of this document  or the Federal
Register notice of proposed standards, write to EPA  Library  (MD-35),
Research Triangle Park, North Carolina 27711.  Specify Standards Support
and Environmental Impact Statement:  Proposed Standards of Performance  for
Stationary Internal  Combustion Engines, report number EPA-450/3-78-125a
when ordering.
2.1    AUTHORITY FOR THE STANDARDS
       Standards of performance  for new stationary sources are established
under Section 111 of the Clean Air Act (42 U.S.C. 7411),  as  amended,
hereafter referred to as the Act.  Section 111 directs the Administrator
to establish standards of performance for any category of new  stationary
source of air pollution which ". . . causes or contributes sign-ificantly
                                    2-1

-------
to, air pollution which may reasonably  be  anticipated  to  endanger public
health or welfare."
       The Act requires that  standards  of  performance  for  stationary
sources reflect, "... the degree of emission  limitation  achievable
through the application of the best technological  system  of  continuous
emission reduction ... the  Administrator  determines  has  been  adequately
demonstrated."  In addition,  for stationary sources whose  emissions  result
from fossil fuel combustion,  the standard must  also include  a percentage
reduction in emissions.  The  Act also provides  that the cost of achieving
the necessary emission reduction, the nonair quality health  and
environmental impacts, and the energy requirements all be  taken into
account in establishing standards of performance.  The standards  apply
only to stationary sources, the construction or modification of which
commences after regulations are proposed by publication in the  Federal
Register.
       The 1977 amendments to the Act altered or added numerous provisions
which apply to the process of establishing  standards of performance.
       1.  EPA is required to list the categories of major stationary
           sources which have not already been  listed and regulated  under
           standards of performance.   Regulations must be promulgated  for
           these new categories on the following schedule:
               25 percent  of the listed categories by August 7, 1980
               75 percent  of the listed categories by August 7, 1981
               100 percent of the listed categories by August 7, 1982
           A governor of a State may apply to the Administrator to add a
           category which  is  not on the list or to revise a standard of
           performance.

                                    2-2

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        2.  EPA is required to review the standards of performance every
            4 years, and 1f appropriate, revise them.
        3.  EPA is authorized to promulgate a design, equipment, work
            practice, or operational standard when an emission standard is
            not feasible.
        4.  The term "standards of performance" is redefined and a new term
            "technological  system of continuous emission reduction" is
            defined.  The new definitions clarify that the control system
            must be continuous and may include a low-polluting or
            nonpolluting process or operation.
        5.  The time between the proposal and promulgation of a standard
            under  Section 111  of the Act is  extended to 6 months.
        Standards  of performance,  by themselves,  do not guarantee
 protection  of  health or welfare because they are  not designed to achieve
 any  specific air  quality levels.   Rather, they are designed to reflect the
 degree  of emission  limitation achievable through  application of the  best
 adequately  demonstrated technological  system of continuous emission
 reduction,  taking  into  consideration  the cost of  achieving such  emission
 reduction,  any nonair quality health  and environmental  impact  and  energy
 requirements.
       Congress had  several reasons for  including  these  requirements.
 First, standards with a  degree of  uniformity  are  needed  to avoid
 situations where some States  may attract industries  by relaxing  standards
 relative  to other States.  Second, stringent  standards enhance the
potential for  long-term growth.  Third,  stringent  standards  may help
 achieve long-term cost savings by  avoiding the need for more expensive
retrofitting when pollution ceilings may be reduced  in the future.
                                    2-3

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 Fourth,  certain  types  of  standards  for  coal  burning sources can adversely
 affect  the  coal  market by driving up  the  price of low-sulfur coal or
 effectively excluding  certain  coals from  the reserve base because their
 untreated pollution  potentials are  high.   Congress  does not intend that
 new  source  performance standards contribute  to these problems.   Fifth,  the
 standard-setting process  should create  incentives for improved  technology.
        Promulgation  of standards of performance does not prevent State  or
 local agencies from  adopting more stringent  emission limitations for the
 same sources.  States  are free under  Section 116  of the Act to  establish
 even more stringent  emission limits than  those established under Section
 111 or  those necessary to attain or maintain the  national  ambient air
 quality  standards  (NAAQS)  under Section 110.   Thus,  new sources may in
 some cases  be subject  to  limitations  more  stringent than standards of
 performance under  Section  111,  and  prospective owners and  operators of  new
 sources  should be  aware of this possibility  in planning for such
 facilities.
       A similar situation may arise  when  a  major emitting facility is  to
 be constructed in  a  geographic area which  falls under the  prevention of
 significant deterioration  of air quality provisions  of Part C of the Act.
 These provisions require,  among other things,  that  major emitting
 facilities  to be constructed in such  areas are  to be subject to best
 available control  technology.  The term "best  available control
 technology"  (BACT),  as defined in the Act, means  ".  .  .  an  emission
 limitation based on the maximum degree of  reduction  of each pollutant
 subject to regulation  under this Act emitted from or  which  results  from
 any major emitting facility, which the permitting authority, on  a
case-by-case basis, taking into account energy, environmental,  and

                                    2-4

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 economic impacts and other costs, determines  is  achievable for  such
 facility through application of production processes  and  available
 methods, systems, and techniques, including fuel cleaning or  treatment  or
 innovative fuel combustion techniques for control of  each such  pollutant.
 In no event shall application of best available control technology result
 in emissions of any pollutants which will exceed the  emissions  allowed  by
 any applicable standard established pursuant to Section 111 or  112 of this
 Act."
        Although standards of performance are normally structured in terms
 of numerical  emission limits where feasible,  alternative approaches are
 sometimes necessary.   In some cases physical  measurement of emissions from
 a  new source  may be  impractical  or exorbitantly expensive.  Section lll(h)
 provides that the Administrator  may promulgate a design or equipment
 standard in those cases  where it is  not  feasible to prescribe or enforce a
 standard of performance.   For example,  emissions of hydrocarbons from
 storage  vessels for petroleum liquids  are greatest  during  tank filling.
 The  nature  of the emissions,  high  concentrations for short periods  during
 filling,  and  low concentrations  for  longer periods  during  storage,  and the
 configuration  of  storage  tanks make  direct emission  measurement
 impractical.   Therefore,  a more  practical  approach  to  standards  of
 performance for  storage vessels  has  been  equipment  specification.
       In addition, Section lll(h) authorizes  the Administrator  to  grant
waivers  of compliance to  permit  a source  to use  innovative continuous
emission control technology.  In order to grant  the  waiver, the
Administrator must find:  (1)  a substantial likelihood  that the technology
will produce greater emission reductions than the standards require, or  an
equivalent reduction at lower economic, energy or environmental  cost;

                                    2-5

-------
(2) the proposed system has not been adequately  demonstrated;  (3)  the
technology will not cause or contribute to  an  unreasonable  risk  to public
health, welfare or safety; (4) the governor of the  State where the source
is located consents; and that, (5) the waiver  will  not  prevent the
attainment or maintenance of any ambient  standard.  A waiver may have
conditions attached to assure the source  will  not prevent attainment of
any NAAQS.  Any such condition will have  the force  of a performance
standard.  Finally, waivers have definite end  dates and may be terminated
earlier if the conditions are not met or  if the  system  fails to  perform as
expected.  In such a case, the source may be given  up to 3  years to meet
the standards, with a mandatory progress  schedule.
2.2    SELECTION OF CATEGORIES OF STATIONARY SOURCES
       Section 111 of the Act directs the Administrator to  list  categories
of stationary sources which have not been listed before.  The
Administrator, ". . . shall include a category of sources in such  list  if
in his judgment it causes, or contributes significantly to, air  pollution
which may reasonably be anticipated to endanger  public  health or
welfare."  Proposal and promulgation of standards of performance are to
follow while adhering to the schedule referred to earlier.
       Since passage of the Clean Air Amendments of 1970, considerable
attention has been given to the development of a system for assigning
priorities to various source categories.  The  approach  specifies areas  of
interest by considering the broad strategy of  the Agency for implementing
the Clean Air Act.  Often, these "areas"  are actually pollutants which  are
emitted by stationary sources.  Source categories which emit these
pollutants were then evaluated and ranked by a process  involving such
factors as: (1) the level of emission control  (if any)  already required by

                                    2-6

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 State  regulations;  (2)  estimated levels of control  that might be required
 from standards  of performance for the source category;  (3) projections of
 growth and  replacement  of  existing facilities for the source category; and
 (4) the estimated incremental amount  of air pollution that could be
 prevented,  in a preselected  future year,  by standards of performance for
 the source  category.  Sources for which new source  performance standards
 were promulgated or  are under development during 1977 or earlier,  were
 selected  on  these criteria.
        The  Act  amendments  of August 1977, establish specific criteria to
 be used in  determining  priorities for all source categories not yet listed
 by EPA.   These  are:
        1.   The  quality  of  air pollutant emissions which each such  category
            will  emit, or will  be designed to emit;
        2.   The  extent to which  each such  pollutant  may  reasonably  be
            anticipated  to  endanger public health or welfare;  and
        3.   The  mobility and  competitive nature  of each  such category of
            sources and  the consequent need  for  nationally applicable new
            source standards  of  performance.
        In some  cases, it may not  be feasible to  immediately develop a
 standard  for a  source category  with a high  priority.  This  might happen
 when a  program  of research is needed  to develop  control  techniques  or
 because techniques for  sampling  and measuring emissions  may require
 refinement.  In  the developing  of  standards,  differences  in  the  time
 required  to complete the necessary  investigation  for  different  source
 categories must  also be considered.   For  example, substantially  more time
may be  necessary if numerous pollutants must  be  investigated  from a single
 source  category.  Further, even  late  in the  development process, the

                                    2-7

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 schedule  for  completion  of  a  standard  may change.   For example,  inability
 to obtain emission  data  from  well  controlled  sources in time to  pursue the
 development process  in a systematic  fashion may force a change in
 scheduling.   Nevertheless,  priority  ranking  is,  and will  continue to be,
 used  to establish the order in which projects  are  initiated and  resources
 assigned.
       After  the source  category has been  chosen,  determining the types of
 facilities within the source  category  to  which  the standard will  apply
 must  be decided.  A  source category  may have  several  facilities  that cause
 air pollution,  and emissions  from  some of  these  facilities  may be
 insignificant or very expensive to control.   Economic studies of the
 source category and  of applicable  control  technology may  show that air
 pollution control is better served by  applying  standards  to the  more
 severe pollution sources.  For this  reason, and  because there be  no
 adequately demonstrated  system for controlling emissions  from certain
 facilities, standards often do not apply  to all  facilities  at a  source.
 For the same reasons, the standards  may not apply  to  all  air  pollutants
 emitted.  Thus, although a source category may be  selected  to be  covered
 by a  standard of performance,  not  all pollutants or  facilities within  that
 source category may be covered by the  standards.
2.3    PROCEDURE FOR DEVELOPMENT OF  STANDARDS OF PERFORMANCE
       Standards of performance must:  (1) realistically  reflect  best
demonstrated control practice; (2) adequately consider  the  cost,  and the
 nonair quality health and environmental impacts  and  energy  requirements of
such  control;  (3) be applicable to existing sources  that  are  modified  or
                                    2-8

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 reconstructed  as  well  as  new  installations;  and (4)  meet these conditions
 for  all variations  of  operating  conditions  being considered anywhere in
 the  country.
       The  objective of a program for  development of standards is  to
 identify the best technological  system of continuous emission  reduction
 which  has been  adequately demonstrated.  The  legislative history of
 Section 111 and various court  decisions make  clear that  the
 Administrator's judgment  of what  is  adequately demonstrated is not limited
 to systems  that are in actual  routine  use.  The search may include a
 technical assessment of control  systems which  have been  adequately
 demonstrated but  for which there  is  limited operational  experience.   In
 most cases, determination  of the  ".  .  . degree of emission reduction
 achievable  ..." is based  on results  of  tests  of emissions  from well
 controlled  existing sources.   At  times, this  has required  the
 investigation  and measurement  of  emissions from control  systems found  in
 other  industrialized countries that  have developed more  effective  systems
 of control  than those  available  in the United  States.
       Since the best  demonstrated systems of  emission reduction may not
 be in widespread use, the  data base  upon which  standards are developed  may
 be somewhat limited.  Test data on existing well  controlled sources  are
 obvious starting points in developing emission  limits for  new  sources.
 However,  since the control of  existing sources  generally represents
 retrofit technology or was originally designed  to  meet an  existing State
 or local  regulation, new sources may be able to  meet more  stringent
emission standards.   Accordingly, other information must be considered
before a judgment can be made  as to the level  at which the emission
 standard should be set.

                                    2-9

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       A process for the development of a standard has evolved which takes
into account the following considerations:
       1.   Emissions from existing well controlled sources as measured
       2.   Data on emissions from such sources are assessed with
           consideration of such factors as: (a)  how representative the
           tested source is in regard to feedstock, operation, size, age,
           etc.;  (b) age and maintenance of the control equipment tested;
           (c)  design uncertainties of control equipment being considered;
           and  (d) the degree of uncertainty that new sources will be able
           to achieve similar levels of control.
       3.   Information from pilot and prototype installations, guarantees
           by vendors of control equipment,  unconstructed but contracted
           projects, foreign technology,  and published literature are also
           considered during the standard development process.  This is
           especially important  for sources  where "emerging"  technology
           appears to be a significant alternative.
       4.   Where  possible,  standards are  developed which permit the use of
           more than one control technique or licensed process.
       5.   Where  possible,  standards are  developed to encourage or permit
           the  use of process  modifications  or new processes  as a method
           of control  rather than "add-on" systems of air pollution
           control.
       6.   In appropriate  cases,  standards are developed to permit the  use
           of systems  capable  of controlling more than one pollutant.   As
           an example,  a scrubber can  remove both gaseous and particulate
           emissions,  but  an electrostatic precipitator is specific to
           particulate  matter.

                                    2-10

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       7.  Where appropriate, standards for visible emissions are
           developed 1n conjunction with concentration/mass emission
           standards.  The opacity standard 1s established at a level that
           will require proper operation and maintenance of the emission
           control system Installed to meet the concentration/mass
           standard on a day-to-day basis.  In some cases, however, 1t  1s
           not possible to develop concentration/mass standards, such as
           with fugitive sources of emissions.  In these cases, only
           opacity standards may be developed to limit emissions.
2.4    CONSIDERATION OF COSTS
       Section 317 of the Act requires, among other things, an economic
Impact assessment with respect to any standard of performance established
under Section 111 of the Act.  The assessment is required to contain an
analysis of:
       (1) the costs of compliance with the regulation and standard
           including the extent to which the cost of compliance varies
           depending on the effective date of the standard or regulation
           and the development of less expensive or more efficient methods
           of compliance;
       (2) the potential inflationary recessionary effects of the standard
           or regulation;
       (3) the effects on competition of the standard or regulation with
           respect to small business;
       (4) the effects of the standard or regulation on consumer cost,  and,
       (5) the effects of the standard or regulation on energy use.
                                    2-11

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        Section 317 requires that the economic impact assessment be as
 extensive as practicable, taking into account the time and resources
 available to EPA.
        The economic impact of a proposed standard upon an industry is
 usually addressed  both in absolute terms and by comparison with the
 control costs that would be incurred as a result of compliance with
 typical existing State control  regulations.   An incremental  approach is
 taken  since both new and existing plants would be required to comply with
 State  regulations  1n the absence of a Federal  standard of performance.
 This approach requires a detailed analysis  of  the impact upon the industry
 resulting from the cost differential  that exists between a standard of
 performance and the typical  State standard.
        The costs for control  of  air pollutants are  not the only costs
 considered.   Total  environmental  costs  for  control  of water  pollutants  as
 well as air pollutants are  analyzed wherever possible.
        A thorough  study of  the profitability and price-setting mechanisms
 of the  Industry 1s  essential  to  the analysis so  that  an  accurate  estimate
 of potential  adverse  economic impacts can be made.   It  1s  also essential
 to know the  capital  requirements  placed  on plants In  the  absence  of
 Federal  standards  of  performance  so  that  the additional  capital
 requirements  necessitated by these  standards can be placed 1n  the  proper
 perspective.  Finally,  1t is necessary to recognize any  constraints on
 capital  availability within an industry, as  this factor  also  influences
the ability of  new plants to generate the capital required for
 Installation of additional control equipment needed to meet the standards
of performance.
                                    2-12

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2.5    CONSIDERATION OF ENVIRONMENTAL IMPACTS
       Section 102(2)(C) of the National Environmental Policy Act (NEPA)
of 1969 requires Federal agencies to prepare detailed environmental  impact
statements on proposals for legislation and other major Federal  actions
significantly affecting the quality of the human environment.  The
objective of NEPA is to build  into the decision-making process of Federal
agencies a careful consideration of all environmental aspects of proposed
actions.
       In a number of  legal challenges to  standards  of performance  for
various industries,  the Federal Courts of  Appeals  have held  that
environmental  impact statements need  not be  prepared by  the  Agency  for
proposed  actions  under Section 111 of the  Clean  Air  Act.   Essentially, the
Federal Courts  of Appeals  have determined  that "...  the best  system of
emission  reduction,  .  .  .  require(s)  the Administrator  to take  into
account counter-productive environmental effects of  a proposed  standard,
as well as  economic  costs  to  the  industry  ..."  On this basis,
therefore,  the Courts  "...  established  a narrow exemption  from NEPA for
EPA determination under Section 111."
        In addition  to  these judicial  determinations, the Energy Supply and
 Environmental  Coordination Act (ESECA)  of  1974 (PL-93-319) specifically
 exempted  proposed actions  under the Clean  Air Act from NEPA requirements.
 According to Section 7(c)(l), "No action taken under the Clean Air Act
 shall be  deemed a major Federal action significantly affecting  the quality
 of the human environment within the meaning of the  National Environmental
 Policy Act of 1969."
                                     2-13

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         The  Agency  has  concluded,  however,  that the preparation of
 environmental  impact statements  could  have beneficial  effects on certain
 regulatory  actions.  Consequently,  while  not  legally required to do so by
 Section 102(2)(C)  of NEPA, environmental  impact statements  will  be
 prepared for various regulatory  actions,  including  standards  of
 performance developed  under Section 111 of the  Act.  This voluntary
 preparation of environmental  impact statements,  however, in no way legally
 subjects the Agency to NEPA requirements.
        To implement this policy, a separate section  is  incuded in  this
 document which is devoted solely to an analysis  of the  potential
 environmental  impacts associated with the proposed standards.  Both
 adverse and beneficial  impacts in such areas as  air and water pollution,
 increased  solid waste disposal,  and increased energy consumption are
 identified  and  discussed.
 2.6     IMPACT  ON  EXISTING  SOURCES
        Section  111  of the  Act  defines  a new source as ". .  . any
 stationary  source,  the  construction or  modification of  which is commenced
 ..."  after the  proposed  standards are published.   An  existing source
 becomes  a new source  if the  source  is modified  or is  reconstructed.  Both
 modification and  reconstruction  are  defined in  amendments  to the  general
 provisions of Subpart A of 40  CFR Part  60  which  were  promulgated  in the
 Federal Register  on December 16,  1975  (40  FR 58416).  Any physical  or
 operational  change  to an existing facility  which results in  an  increase 1n
 the emission rate of any pollutant for  which a  standard  applies is
 considered a modification.  Reconstruction,  on the other hand, means  the
replacement of components of an existing facility to  the extent that  the
fixed capital cost exceeds 50 percent of the cost of constructing a

                                    2-14

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comparable entirely new source and that it be technically  and economically
feasible to meet the applicable standards.  In such cases, reconstruction
is equivalent to new construction.
       Promulgation of a standard of performance requires  States to
establish standards of performance for existing sources  in the  same
industry under Section lll(d) of the Act  if the standard for new sources
limits emissions of a designated pollutant (i.e., a pollutant for which
air quality criteria have not been issued under Section  108 or  which  has
not been listed as a hazardous pollutant  under Section 112).  If a State
does not act, EPA must establish such standards.  General  provisions
outlining procedures for control of existing  sources  under Section lll(d)
were promulgated on November 17, 1975, as Subpart B of 40  CFR Part 60
(40 FR 53340).
2.7    REVISION OF STANDARDS OF PERFORMANCE
       Congress was aware that the level  of air pollution  control
achievable by any industry may improve with technological  advances.
Accordingly, Section 111 of the act provides  that the Administrator  ".  .  .
shall, at least every 4 years, review and, if appropriate, revise  .  . ."
the standards.  Revisions are made to assure  that the standards continue
to reflect the best systems that become available in  the future.   Such
revisions will not be retroactive but will apply to stationary  sources
constructed or modified after the proposal of the revised  standards.
                                    2-15

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                                  CHAPTER  3
               THE  STATIONARY  RECIPROCATING  INTERNAL  COMBUSTION
                         ENGINE  PROCESS  AND  INDUSTRY
 3.1    GENERAL
       Stationary  reciprocating  Internal  combustion  (1C)  engines  operate  on
 the same principles  as the common  automobile or  truck engine.  They  can be
 Installed  almost anywhere, since  they can be Instrumented for remote
 operation, can use gasoline,  dlesel fuel, natural gas, sewage gas, and
 certain mixtures of  these fuels,  and require relatively Uttle water.
 Engines are manufactured 1n sizes  ranging from less  than  1 hp to  nearly
 50,000 hp, although  the  largest  one bunt 1n the United States 1s 13,500  hp.
 Installations  characteristically  have a low physical profile (low buildings,
 short stacks,  little visible  emissions, and quiet operation when  properly
muffled),  at least when  Installed  as single units.   They  are often located
 in, or adjacent to,  large urban  centers, where power demands are  greatest
 and pollution  problems are often the most severe.
       1C  engines  are being used  in a multitude of applications because of
their short construction time, ease of installation, and remote operation
capability with a  variety of  fuels over a large range of speeds and loads.
These applications range from driving large municipal electrical  generators
to powering small  air compressors  and welders.   Further details about the
manufacturers  and users of 1C engines are presented  1n the following
subsections.
                                   3-1

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  3.1.1
         Approximately  40  firms manufacture  1C  engines  for  stationary
  applications  1n the United States,  and many others  produce  forglngs,  fuel
  systems, turbochargers,  heat exchangers, and  related  components.   In
  addition, many Original  Equipment Manufacturers  (OEM's) purchase  engines to
  incorporate into such final products as trucks,  tractors, compressors,
  welders, pumps, generator sets, and other machinery.  These OEM's  are
  significant customers for some manufacturers, particularly those who make
  truck and tractor engines.  One such manufacturer has stated that  he sells to
 about 400 OEM's,  whereas  another claims his company deals with 40(1).  in
 addition, several  of the  manufacturers of small- and medium-sized engines sell
 their product  to  dealers  and  distributors,  who,  in turn,  sell  them to the end
 users.   Therefore,  the manufacturing companies have little knowledge or
 control  over the  end-use  of their  engines.   To further complicate the
 situation,  some engine manufacturers are  themselves OEM's;  they buy engines
 from  other manufacturers  in size ranges that they do not  produce,  and then
 mate  these purchased engines with  their own  compressors,  generators,  etc.
       For the purposes of this  discussion, manufacturers  of 1C engines  can
 be  categorized into four  major groups:  (1) firms manufacturing large-bore
 (greater  than 8 inches),  low- and medium-speed  (less than  1200  rpm)  engines;
 (2) firms manufacturing principally  small-bore  (less than 6-1/2  inches),
medium-power, high-speed  engines (greater than 1200  rpm); (3) firms
manufacturing low-power (less than 100 hp), high-speed engines  and  generator
sets;  and (4) firms which manufacture small (less than 20 hp) one-cylinder,
air-cooled gasoline engines principally used for  lawn and garden equipment.
Table  3-1(2)  shows these firms  in their respective categories.   Although
there  is  some overlap in power  ratings offered by members of the first three
                                   3-2

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                       TABLE  3-1.   1C ENGINE MANUFACTURERS
                                                                   (2)
Manufacturer
Large Bore Eng1ne_s
AT co
Colt
Cooper- Bessemer
ElectroMotlve D1v (GM)
Enterprise
Dresser-Clark
Ingersoll-Rand
Worth1ngtonc
White Superior
Medium Bore Engines
AlHs-Chalmers
Case
Caterpillar
Chevrolet-Oldsmoblle (GM)
Chrysler
Cooper- Pen j ax
Cummins
Detroit Diesel
Ford
International Harvester
John Deere
M1nneapol1s-Mo11ne
Murphy
Sterling
Stewart and Stevenson
Teledyne Continental
Waukesha6
White Engines (Hercules)
Bore,
Inches

9
8 - 16
13 - 20
9
13 - 17
17 - 19
11 - 17
14 - 16
8 - 14

3-1/2 - 6
3.3/4 - 4-1/8
4-1/2 - 6-1/4
3-7/8 - 4-1/4
3-1/4 - 4-1/4
5 - 15
4-1/2 - 6-1/4
3-7/8 - 5-3/4
4-1/8 - 4-1/2
3-7/8 - 5-3/8
4 - 4-3/4
4-1/4 - 5-5/16
5-1/2 - 6-3/8
3 - 5-1/2
3-7/8 - 4-3/4
3-7/8
3-5/8 - 9-3/8
3.3/4 - 4-1/2
CID/cy1a

666
1037-3526
2155-6283
645
1200-4770
3860-5100
1350-4993
2972-4021
510-825

43-169
47-84
79-246
26-57
28-52
128-2827
63-192
53-149
26-67
39-136
55-89
71-133
142-207
16-166
53-149
28-41
38-586
35-80
Power
Range,
hpt>

1000 - 4400
850 - 9400
900 - 13500
800 - 3600
1600 - 13500
1000 - 10000
1000 - 5500
2300 - 8600
400 - 2650

29 - 850
50 - 125
85 - 1000
50 - 215
43 - 175
15 - 300
120 - 1200
50 - 1100
38 - 200
16 - 325
44 - 180
90 - 180
110 - 520
16 - 152
30 - 1100
50 - 80
52 - 1550
34 - 130
Cylinder
Power,
hp/cyl

175 - 250
175 - 500
360 - 675
100 - 180
280 - 680
200 - 500
125 - 330
125 - 330
75 - 150

10 - 70
12 - 30
21 - 63
13 - 27
12 - 30
15 - 150
20 - 100
20 - 68
9 - 22
9 - 50
15 - 30
15 - 29
30 - 60
8 - 20
20 - 68
12 - 14
8 - 110
12 - 26
Speed t§
Range, H
rpm

400-1200
500-900
250-600
900
400-600
300-330
300-550
300-500
900-1000

1200-2600
1200-2200
1200-2400
3600-4000
1200-4000
200-900
1200-2100
1800-2500
2500-4600
1800-3000
1500-2500
1800
1200-1800
1200-1800
1200-1800
2000-2400
1000-1800
2400-2800
bHoriHowir l^for^ated SndltlonMcontlnuoui operation)  9 130°F Intercooler water temperature for
 large-bore engines and 85°F Inlet air temperature for medium-bore engines.
StortMngton ceased producing engines during the writing of this report.
dTh1s  manufacturer produces high power one- and two-cylinder engines.          ,^^tu ftf ono
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                    TABLE 3-1.  Concluded
Manufacturer
Small Engines and Generator Sets
Kohler

Onan
Teledyne Wisconsin
Wills Industries
W1tte
•»
Very Small Engines
BMggs and Stratton
Chrysler
Clinton
Home Ute
Jacobsen

Outboard Marine Corp.
(Lawn Boy)
McCulloch
O&R
Tecumseh
«...
Bore,
Inches


"""""*
3-1/4
2-3/4 - 4-1/8
4-1/4 - 5

2-3/B - 3-9/16
2 - 2-1/4
2-1/2 - 2-3/8
1-7/16 - 2-3/4
2-1/8

2-3/8
1-3/8 - 2-1/4
1-1/8 - 1-17/32
2-3/8 • 3-1/2
CID/cy1a












Power
Range,
hpb


3-3/4 - 28
8-30
3-1/2 - 80
11 - 28
9 - 27

2 - 16
3-1/4 - 8
4 - 7
2 - 4

3
<10
<20
1 - 2-1/4
2-1/2 • 16
Cylinder
Power,
np/cyl


3 - 7
6-8
3-1/2 - 20
11 - 14
9 - 14

2 - 16
3-1/4 - 8
4 - 7
2-4

3


1 - 2-1/2
2-1/2 - 16
Speed \o
Range, H-
rpm


2000-2700
1800-3900
2400-3600
3000
800-1800

3100-4000
500-7000
600-5800

3800


300-7200
500-3600
*Cub1c Inch displacement per cylinder
 ttsss :^^^«iff jrsssitysra/jss: sgsr •* ~« *
                          3-4

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groups (Figure 3-1), the differences tend to be more distinct when viewed on
a power-per-cylinder, displacement-per-cylinder, or bore basis (Figures 3-2,
3-3, and 3-4).  The latter two show the clearest division between medium- and
high-power engines, with only Waukesha and Cooper-Penjax straddling the two
categories.  More significant, however, is the fact that the market
interactions between firms in the different groups are of far less importance
than the interactions within the groups.  Thus, the stationary 1C engine
industry is in many ways four industries, each with its own markets and
problems.
       Any 1C engine can be adapted for use in stationary applications (for
example, automotive engines are easily adapted for irrigation pumps).  Thus,
any engine manufacturer is a potential source of stationary engines.
However, the following discussion will concentrate only on those
manufacturers who market engines specifically for stationary applications.
       All but three of the manufacturers are divisions or subsidiaries of
large, diversified corporations with stationary engine sales accounting for
a small part of total corporate revenue.-'  Total sales of stationary
engines are in the range of $300 million to $400 million per year.  Since
most firms manufacture engines for nonstationary as well as stationary
applications, it is difficult to determine employment directly attributable
to  stationary engines.  Assuming, however, that the percentage of employment
at  a plant attributable to stationary engines  is equal to the percentage of
sales  attributable to stationary engines, it  is estimated that between 15,000
•I/The discussion  in this paragraph excludes manufacturers of engines
  under 20 hp.  Their annual sales are  also in  the range of $300 million
  to $500 million.
                                    3-5

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co
i
at
SMALL BORE
WITTE
WILLS IND.
OMAN
KOHLER
WISCONSIN
MEDIUM BORE
CHRYSLER
JOHNDEERE
CHEVROLET (GM)
CASE
HERCULES (WHITE)
STERLING
NPLS-MOLINE (WHITE)
FORD
CONTINENTAL
COOPER-PENJAX
INTERNAT. HARV.
MURPHY
CUMMINS
ALLIS-CHALMERS
STEWART-STEVENSON
CATERPILLAR
DETROIT DIESEL (GM)
WAUKESHA
LARGE BORE
WHITE SUPERIOR
EMD (GM)
ALCO (WHITE)
INGERSOLL'RAND
WORTHINGTON
COLT
DRESSER-CLARK
COOPER BESSEMER
ENTERPRISE
1- 1 I 	 1 	 , 	 -,
1 , 1
1 1
1 )
1 '
I |

I I
1. 1
1
1 |

1 1
, 1 i
1 ,
1 1
I 1
1 1

Ii 1 '
1 |
' \.
'

L ]

1 . 1
1 i
1

i I
r 	 i

i
— i i ^
10 100 1000 10000
                                                                   HORSEPOWER
                          Figure 3-1.   Manufacturers categorized by engine horsepower.

-------
CO
I
SMALL BORE
WITTE
WILLS IND.
ONAN
KOHLER
WISCONSIN
MEDIUM BORE
CHRYSLER
JOHNDEERE
CHEVROLET (GK)
CASE
HERCULES (WHITE)
STERLING
MPLS-MDLINE (WHITE)
FORD
CONTINENTAL
COOPER-PENJAX
INTERNAT. HARV.
MURPHY
CUMMINS
ALLIS- CHALMERS
STEWART-STEVENSON
CATERPILLAR
DETROIT DIESEL (GM)
WAUKESHA
LARGE BORE
WHITE SUPERIOR
EMD (GM)
ALCO (WHITE)
INGERSOLL-RAND
WORTHINGTON
COLT
DRESSER-CLARK
COOPER BESSEMER
ENTERPRISE
1 1 •" - -
oQ
1 I

1 I
I i

i

i
i i
i i
1 1
i i
I i
i i
i i
i

i

i i

i i
i i
i i


i i
i 1
i i
i J
i «
                                                           10
100
1000
                                                                  HP/CYL
                    Figure 3-2.   Manufacturers categorized by engine  horsepower per cylinder.

-------
CO
I
CO
MEDIUM BORE
CONTINENTAL
CHRYSLER
CHEVROLET (GH)
FORD
HERCULES (WHITE)
CASE
JOHN DEERE
NPLS-NOLINE (WHITE)
INTERNAL HARV.
CUMMINS
STEWART-STEVENSON
DETROIT DIESEL (GM)
STERLING
ALLIS-CHALMERS
MURPHY
CATERPILLAR
UAUKESHA
COOPER- PENJAX
LARGE BORE
EMD (GM)
ALCO (WHITE)
WHITE SUPERIOR
COLT
WORTHINGTON
ENTERPRISE
INGERSOLL-RAND
COOPER-BESSEMER
DRESSER- CLARK
	 T— 	 r— 	 	 	
1 	 1 ,
,' 1
i ,
i , I .
1 . ., 	 L
r i
1,1
r i
i . \
I . —. 1
1

1 _._. _1
i \
1 1 ,
. ! 1 ,. . .
i 1
i 1
*
1 , I
i |
« 1
1 , 1,
7 	 	 , , l
1 	 _ _ _,.J
i-i
                                                     100
                                                                                    1,000
                                                                                                                  10,000
         Figure  3-3.   Manufacturers of medium and large engines categorized  by  cylinder displacement, in'/cyl.

-------
CO
1
MEDIIM BORE
CONTINETfTIAL
CASE
CHRYSLER
CHEVROLET (SI)
hERCULES (WHITE)
FORD
DETROIT-DIESEL
STEWART-STEVENSON
JOHN DEERE
HPLS-iWLIHE (WHITE)
IrfTERWT. HARV.
STERLING
CUMINS
ALLIS- CHALMERS
CATERPILLAR
MURPHY
UAUKESHA
COOPErf-PENJAX
LARGE BORE
ALCO (WHITE)
EMD (GM)
WHITE SUPERIOR
COLT
WORTHINGTON
IHGERSOLL-RAND
ENTERPRISE
DRESSER-CLARK
COOPER-BESSEMER
1
I
1
1
lH-i
I ]
1 -, J ,
1 J
I . , . 1,
•— H
• 1 , ,
1 |
T
(."_, ... . 1 _
1

i
I
~1
( I
i
                                                                   10
                                                                                                                100
                 Figure 3-4.  Manufacturers of medium and large engines categorized by bore  size,  in.

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and 30,000 people are employed directly  in the manufacture  of  stationary
engines.

3.1.1.1  Large-Bore, High-Power, Low- and Medium-Speed Engines
       Most of the large-bore, high-power (>100 hp/cylinder) engines
manufactured are four-cycle, compress ion-ignition engines designed  to  operate
on either diesel oil or a mixture of oil and natural gas  (dual fuel).  The
remainder of the engines are spark-ignited natural gas engines,  about  equally
distributed between two- and four-cycle  varieties.  Some  engines  are built  to
operate as either spark-ignited or compression-ignited (dual fuel or oil) and
can easily be switched in the field in response to fuel availability.
Production of large-bore engines for stationary applications is  currently in
the range of 1000 to 2000 units/year with a total production value  of  $80
million to $150 million.  Sales have been largely constant  over  the last 5
years, with some firms showing a slight  growth and others,  particularly those
manufacturing gas engines, having declining sales.  These manufacturers
expect sales to grow at an annual rate of 5 to 10 percent,  on a  total
horsepower basis, for the next 5 years as demand increases  for engines for
nuclear standby and natural gas pipelines (see Section 7.1.2).   Between 5000
and 6000 people are employed in the manufacture of stationary high-power
engines.
       As Figure 3-1 indicates, there is a region of overlap between the
power ranges offered by the manufacturers of large- and medium-bore engines.
There are basic differences, however, which separate the two groups.   Large-
bore engines produce high-power output at low speeds due to their large
displacement and consequent high power per cylinder.  Smaller bore engines,
in contrast, have lower power per cylinder (and therefore more cylinders for
                                   3-10

-------
 the  same  engine  horsepower)  and  achieve  high  outputs  by  utilizing  high
 rotative  speeds.   Thus,  for  the  same  power  rating,  high-speed  engines  are
 smaller,  less  expensive,  and capable  of  running  at  a  wider  range of  speeds.
 Low-speed,  large-bore  engines, on  the other hand, are more  economical  to
 operate continuously because of  lower fuel  consumption and  longer  lifetimes.
 For  these  reasons,  high-speed  engines tend  to  find  different applications
 (see below) than  low-speed engines  of the same power, and there  is little
 competition between firms in these  two groups.

 3.1.1.2  Medium-Power, High-Speed  Engines
       The  firms manufacturing medium-size, high-speed engines (110  to  100
 hp/cylinder and  greater  than  1000  rpm) vary greatly in size, employing  from
 less than  200  to more  than 10,000  people in engine  manufacturing.  Although
 four firms, Cummins, Caterpillar,  Detroit Diesel Allison Division of General
Motors, and Ford,  dominate diesel  engine production (with annual sales  of
60,000 to  120,000  units  each), they concentrate their sales in the truck,
 tractor, construction,  and material handling markets(3).   Ford, General
Motors, and International Harvester also manufacture  significant quantities
of gasoline-fueled truck and tractor  engines.   Therefore, most of the
stationary engines produced  by these  manufacturers  are mobile engines
modified for stationary  installation  and constant speed operation.   Three
additional firms,  International Harvester, Waukesha,  and  Teledyne
Continental, each sell  about as many  engines for stationary applications
(5000 to 15,000 per year) as do the four larger companies(4,5,6).  The
remaining  manufacturers in this group are smaller.
       Medium-power engines  are predominantly  gasoline-  and  diesel-fueled;
natural gas engines are less important.  Because of  the  wide range  of
                                   3-11

-------
 power offered,  from 50 to 1500 hp,  these engines are used in a wide variety
 of miscellaneous industrial,  commercial, nonpropulsive marine, and
 agricultural  applications where shaft power is needed and electricity is
 either  unavailable  or inappropriate (see Chapter 3.1.2).
        Although  precise production  data are unavailable,  we estimate that
 sales of  diesel  medium-power,  high-speed engines for stationary applications
 have  been in  the range of 60,000 to 80,000 units/year over the past 6 years
 with  a  total  value  of $150 to  $200  million per year (FOB  plant),  and annual
 sales for gasoline  medium-power, high-speed engines have  been approximately
 100,000 with  a  total  value of  $50 million  (FOB plant).  Sales of  these
 engines have  been erratic from one  year to the next,  but  the general trend
 seems to  be upward.   The  industry expected this  growth  to continue at  about
 the same  range  as the  economy  (that  is,  at 3  to  5 percent per year)  before the
 recent  downturn  and  concomitant  economic uncertainties!7^).
 3.1.1.3   Small Engines
        Five firms are  classified as manufacturers  of  small  engines and
 generator  sets.  These  manufacturers  are distinguished  from  the previously
 discussed manufacturers in  that  they  produce mostly one-  and  two-cylinder
 engines of less  than 50 horsepower.   Although  there  is  some  overlap  between
 the power ranges offered  by the  manufacturers  of medium-power, high-speed
 engines and those of small  engines, most of the  engines sold  by the  former
 group are larger than 50  horsepower.
       The engines produced by the five  manufacturers in  this  group  are
mostly diesel  and gasoline, one-  and  two-cylinder models.   The firms also
 produce some four-cylinder models.  All  have four  strokes per  power  cycle,
 and four of the firms produce air-cooled engines.  Onan, Kohler,  and Wills
                                   3-12

-------
  produce mainly engine-generator sets  --  small,  semlportable  Integral  engines
  and generators that are used to provide  electrical power  1n  remote  locations,
  Other applications for the engines  Include power for small pumps  and  blowers
  and off-the-road vehicles.  A particularly Important application  for  some
  manufacturers 1s refrigeration compressors for trucks and railroad  cars, and
  hydraulic pumps for tractor-trailer dump trucks and trash compactors.  Sales
  of small  engines  are in the range  of $75 to $100 million per year,  and
  employment  is approximately 4000 to 6000.

  3.1.1.4   Very Small  Engine Manufacturers
        In addition  to  the  manufacturers  discussed above,  there are at least
  10  firms which produce  one-cylinder, air-cooled  gasoline  engines  rated at less
  than 20 hp.   These firms sell about  12.5  million engines  per  year (1973)  with
  a total product value of $400 m1ll1on(9).  Therefore, the  unit wholesale  cost
 of each engine is about $30.  These engines are used primarily for lawn and
 garden equipment and chain saws, and to a lesser degree for recreational
 vehicles,  such as  snowmobiles and small all-terrain  vehicles.  The dollar
 sales of  these engines  constitutes  60 percent of the value of  all gasoline
 engines (except automotive, outboard, truck,  bus, tank,  and aircraft) and is
 approximately equal  to  the  dollar sales of all  other stationary engines
 (estimated at $300 million  to  $400  million annually,  as  mentioned above).
 3.1.2   Engine Users
        On the basis of  Installed  horsepower, the  principal  stationary
 applications  of 1C engines  are the following:  oil and gas  pipelines, oil  and
 gas production, general   Industrial (Including construction), electrical  power
generation, and agriculture.  Table 3-2(10-32) shows estimated  1C  engine
applications   and usage patterns by fuel.
                                   3-13

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                                          TABLE 3-2.  STATIONARY ENGINE APPLICATIONS



Category









DIESEL
Oil & Gas Production
Offshore drilling
Land drilling
Oil & Gas Transport
Electric Generation

General Industrial
& Agriculture
Municipal water
supply
Marine nonpropulsive


Construction, small
Miscellaneous, large6
Construction, large ,
Portable compressors
Welders
Pumps
Generator sets(stand by)
<50 kW
50 kW - 400 kW
400 kW - 1000 kW


C
o


•a ^
girt
4->
a. -r-
c

a
3
C
C


} 800C
50C
150C



200C
5, 00^


5,000
1,700
5,000
9,000
8,000
5,000

7,000
8,000
1,500




to

C
o
•»—
•*-> (/)

It,

r— fc.
1O -*~
3
C
5


2000
2000
6000
2600



3000
3500


500
100
500
500
500
1000

500
250
100
1
C
o
-§ <«o
8^"^
- i-

t, "^ "^
g - ex.
f— "^
le
3
C
C









62.5


62.5
56.3
300.0
168.8
110
250

35.0
250
56.3
1
C
o
elx

01,5?^

g"« j:
"MO.
^™ .^ ^^
lO

C
5


378
1,708
4,800
2,160



567
1,875


625
1,125
3,000
1,688
1,000
1,250

350
5,000
1,125



•o
a
o
-1
c
to
4J
I/I
C
O



X




X







X
X


X
X



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a
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a>
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^

i.
a


X
X

X




X


X

X
X
X


X
X
X



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01
a.
in
c
id
4^

C
o
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X



X








X

X
X
X



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ai
^3
ID

S-
£


X
X
X





X


X

X
X
X





	 — c
ll
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t


Basis of Estimate6











AGA Market Study
AGA Market Study
McGowin, Gas Facts
FPC, Diesel & Gas
Power Costs


AGA Market Study
Current Industrial
Report, Industry
contacts










GO
       Footnotes appear at end

-------
                                                       TABLE 3-2.   Continued
CJ



tn






Category




DUAL FUEL
Oil S Gas Transport

Electric Generation


NATURAL GAS9
Agriculture
Oil & Gas Production
Oil & gas well pumps
Secondary recovery
Well drilling
Plant processing
Oil & Gas Industry
Utility compressors"



Electric Generation
Private/public
utility
Commercial -
institutional
Stand-by
Industrial on-site




c

u s-
•o-^
O I/)
Q_ •!-
c
IB
C

I included
> in
) Diesel




















to
c
o
•~ "c
o
0.

I included
f in
) Diesel


91,000

266,000
5,600
3,050
4,000

( 4,500
<
( 4,000



450
2,000
1,500






»
•— s-
to Jr
3
5

6000



0.75

0.7
0.8
0.8
0.8

0.9

0.8


0.8
0.45
0.9
0.6
2500

3500
6000
2000
8000

6000

6000



4000
50
4000
1
c
o
y ^
o
s-1^ x


5-ji.
ID
3
C
C

















1
C
0
<-> in<°
3 +-> O
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S- =3 X
Q.
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>> 01 >>
O>l 	 ^s.
1. i— I-
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UJ VI O.
1 — •— t

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4J
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X


X

X
X
X
X

X

X


X
X
X
X






•o
CD
a.
a>
J3
n)

X





















Basis of Estimate6





McGowin, Gas Facts
FPC, Diesel & Gas
Power Costs

AGA Market Study

AGA Market Study
AGA Market Study
AGA Market Study
McGowin

Southwest Research
Institute1
Southwest Research
Institute1

FPC, Diesel & Gas
Power Costs
AGA Market Study
AGA Market Study
AGA Market Study
                                                                                                                                    . oo
                                                                                                                                     to
       Footnotes appear at end

-------
                                           9L-£
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-------
                                                               TABLE  3-2.    Concluded                                                   g
                                                                                                                                             i
               Footnotes


               aAnnual  production multiplied by life in  years  (based on  estimated  service life of 5000 hours for diesel engines, 4000 hours
                for  gasoline engines, or as noted)  to compute  population
               t>See  References 10 through 32 for complete  titles  of these  sources.
               cApproximated, based on estimated population and annual  usage
               d7500-hour service life assumed
               eApplications include pumps, snow blowers,  aircraft turbine starters, etc.
               ^Excludes mobile refrigeration units
               Population estimates come from the  AGA market  study.  Annual production  is  not estimated  for this  category since production
                has  been changing rapidly, decreasing continuously since 1966  (see Figure 8-3) and,  therefore,  an  annual  estimate  of produc-
               .tion would be misleading.
               • Includes transport, distribution, gathering, and  storage
               ^Reference 24
               jjPull  combines, balers, sprayers, dusters,  etc.
                Estimated service life of 5 years
CO
i

-------
       Pipeline installations  are concentrated in the oil  and gas  producing
states on the Gulf Coast and in the Midwest  as shown in Figure 3-5(a)(33).
Electric generation includes base load generation, principally for municipalities
in the plains and Midwest,  emergency standby for vital public services  and
large buildings in urban areas, and remote generation (for mines and homes)
in rural areas.  Agriculture applications are primarily irrigation pumping,
concentrated in those areas with irrigated farm lands, as shown in Figure
3-5(b)(34).  Additional agricultural applications include frost control, harvesting
(auxiliary engines), and some remote electric generation.  Construction applications
include portable compressors, welders, pumps, electric generation, and material
handling equipment.
       For applications other than electric power generation, 1C engines
often compete with electric motors.  Engines  involve  a higher initial
investment but have  an  advantage in locations where  gas and fuel oil are less
expensive than electricity, such as remote or temporary construction sites.
Thus, engines  tend to  be concentrated in  areas where  electric power
generation  and transmission costs  are high,  as  in the mountain  and prairie
states,  or where  fuel  costs  are  low,  as  in the  gas-producing  areas along the
Gulf Coast.
 3.2    PROCESSING AND  THEIR EMISSIONS
                                             2.1
 3.2.1  Fundamental  Description of  1C  Engines-
        Reciprocating internal  combustion  engines  produce  shaft  power by
 confining a combustible mixture in a  small  volume between the head of  a
 piston  and its surrounding cylinder,  causing this mixture to  burn,  and
 -Much of the material  in this  section is  drawn  from References  35 and 36.
   These books describe  the operation of 1C engines  in considerable detail.
                                    3-18

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CO





IQ
                Figure 3-5(a).   Potential  users of  stationary reciprocating engines:   irrigated farms.(33)

-------
                                 FEDERAL POWER COMMISSION
Figure 3-5(b).  Major natural gas

-------
 allowing  the  resulting  high-pressure products of combustion gases to push the
 piston.   Power  is  converted  from linear to rotary form by means of a
 crankshaft.
       There  are two methods of  igniting the fuel  and air mixture.  In
 compression  ignition  (CI)  engines,  air is compression heated in the cylinder,
 and  diesel fuel  is  then injected into the hot air.   Ignition is spontaneous.
 A  different  approach, however,  is used for gasoline  or gas-fueled engines
 where  combustion is initiated by the spark of an electrical  discharge.
 Therefore, these units  are spark ignition (SI)  engines.   Usually the fuel is
 mixed  with the  air  in a carburetor  (for gasoline)  or  at  the intake valve (for
 natural gas), but  occasionally the  fuel is injected  into the compressed air
 in the cylinder.  Although all diesel-fueled engines  are compression ignited
 and  all gasoline and gas-fueled  engines are spark  ignited,  gas  can be used in
 a  compression ignition  engine if a  small  amount  of diesel  fuel  is injected
 into the  compressed gas-air  mixture to initiate  burning.   Such  "dual fuel"
 engines are usually designed to  burn  any mixture ratio of  gas  and diesel  oil,
 from 6- to 100-percent  oil (based on  heating value).
       CI engines can operate at  a  higher  compression  ratio  (ratio of
 cylinder  volume when the piston  is  at  the  bottom of  its  stroke  to volume when
 it is  at  the top) than  SI engines because  fuel  is  not  present during
 compression and hence there  is no danger  of premature  auto-ignition.  Since
 the thermal efficiency  of an engine increases with increasing pressure  ratio
 (and pressure ratio varies directly with  compression  ratio), CI  engines  are
more efficient than SI  ones.   This  increased  efficiency  is  gained at the
 expense of poorer acceleration and  a  heavier  structure to withstand  the
 higher pressures.
                                   3-23

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        In  addition,  engines  may  be  described  by  the  number of strokes per
cycle  (two or four)  and  the  method  of  Introducing  air  and fuel  Into the
cylinder.
        In the four-stroke  cycle, the sequence of events  may be  summarized as
follows  (see Figure  3-6)(37):
        1.  Intake  stroke —  suction of  the  air or  air  and fuel  mixture Into
           the  cylinder  by the downward motion of  the  piston
        2.  Compression stroke — compression  of  the  air  or air  and  fuel
           mixture,  thereby  raising its temperature
        3.  Ignition  and  power (expansion) stroke —  combustion  and  consequent
           downward movement of  the piston  with  energy transfer to  the
           crankshaft
       4.  Exhaust stroke  -- expulsion  of the  exhaust  gases  from the  cylinder
           by the upward movement of the piston
This description applies to  a naturally aspirated  engine,  which utilizes  the
vacuum created behind the  moving piston to  suck  in the fresh air  charge.
However, many engines now  pressurize the air  cylinder.   This may  be done  with
either a turbocharger or a supercharger.  The  turbocharger is powered  by  a
turbine that is driven by  the energy in the relatively hot exhaust  gases,
while a supercharger is driven off the engine  crankshaft.  Air  pressurization
is used to increase the power density, or power  output per unit weight  (or
volume) of the engine.  Since the density of  air increases with  pressure, the
mass of air that can be introduced into the cylinder increases  with pressure.
Furthermore,  since the air-to-fuel  ratio at maximum power  is  fixed by
combustion requirements,  more fuel  can be introduced into  the cylinder with
high pressure air than with atmospheric pressure air;  hence,  more power can
be obtained from a given cylinder configuration.   As the  air pressure  1s
                                   3-24

-------
                       Intake

                  Spark Plug


                      Cylinder


                        Puton

                    Cant
                (and Crankshaft)

            INTAKE STROKE
           Intake valve opens,
          thus admitting charge
          of fuel and air Exhaust
         valve closed for most of
               stroke.
 COMPRESSION STROKE
    Both valves closed.
    Fuel-a»r mixture >s
   compreMed by rising
   piston. $park ignites
   mixture near end of
        stroke.
                                           Connecting
                                              Rod
                     Intake
                    Manifold
      POWER OR WORK STROKE
        fuel-air mixture burns,
        increasing temperature
        end pressure, e«pansion
        of combustion gases
        dwei puton down. Both
        valves closed—Exhaust
        valve opens near end of
             stroke
                                           Exhaust
                                          Manifold
 EXHAUST STROKE
 Exhaust valve open,
 eihaus* products are
displaced from cylinder.
Intake valve opens near
   end of stroke
                                  Exhaust
Figure  3-6.    The  four-stroke,  spark-ignition  (SI)  cycle.    Four  strokes  of
                   180   of  crankshaft  rotation  each,  or  720° of  crankshaft  rota-
                   tion  per  cycle(37).
                                              3-25

-------
 increased,  its temperature is also raised.   Therefore, the pressurized air is
 often  cooled before entering the cylinder to further increase power.  This
 process  is  called intercooling or aftercooling.   In fact, all high power
 turbocharged natural  gas-fueled engines  are intercooled to prevent premature
 auto-ignition of the  fuel  and air mixture(38).
        In a CI engine,  fuel  is injected  into the cylinder near the end of the
 compression stroke; whereas,  in an SI  engine,  the fuel is usually added to the
 air, downstream of  the  turbocharger if any  is  used,  before the mixture enters
 the  cylinder.   In some  SI  engines (particularly  large natural gas-fueled
 ones), the  fuel  is  injected  into the  intake manifold just ahead of the
 valves.  For CI  engines  or SI engines  using fuel  injection instead of
 carburetors,  the fuel or fuel-air mixture can  be  introduced  by "direct
 injection"  into  the cylinder  head and  communicates  with  the  principal
 combustion  volume.  Direct injection units  are also  called open  chamber
 engines because  combustion takes  place in the  open  volume between  the top of
 the piston  and the cylinder.   This  design contrasts  with  indirect  injection
 engines, where  the combustion  begins in  a fuel-rich  (oxygen  deficient)
 atmosphere  in  the smaller  antechamber  and then expands into  the  cooler,
 excess air  region of the main  chamber.   These  latter  engines  are  also called
 divided or  precombustion chamber  systems  (swirl chamber  if the  small
 antechamber  is specially designed  to promote swirl --  see Section  4.4.8).
Prechamber  designs can be used  in  carbureted engines  as well, but  they  have
not yet been applied to engines built exclusively for  stationary
applications.
       There are three major advantages of divided chamber engines:   less
sensitive to fuel variations;  lower stresses on the mechanical parts, such as
connecting  rods, crankshaft,  etc., because of a lower pressure rise rate
                                   3-26

-------
during combustion; and lower NOX production.  All three of  these  benefits  are
a result of incomplete primary combustion with an oxygen deficiency.
Therefore, by comparison with open chamber designs, combustion  is  less
sensitive to fuel droplet spray patterns, the complete combustion  process
takes longer, and less oxygen is available to combine with  nitrogen  in  the
initial high-temperature reaction.  These benefits  are attained at the  expense
of up to 30 percent greater heat rejection (due to  the surface  area  added  by
the antechamber)  and consequent 5- to 8-percent fuel penalty(39,40).
       In a two-stroke design, the power cycle is completed  in  one revolution
of the crankshaft as compared to two revolutions for the four-stroke  cycle
(see Figure 3-7).  As the piston moves to the top of the cylinder, air,  or  an
air and fuel mixture, is compressed for ignition.   Following  ignition and
combustion the piston delivers power as it moves down.  Eventually it uncovers
the exhaust ports (or exhaust valves open).  As the piston  begins  the next
cycle, exhaust gas continues to be purged from the  cylinder,  partially  by  the
upward motion of  the piston and partially by the scavenging  action of the
incoming fresh air.  Finally, all ports are covered (and/or  valves closed),
and the fresh charge of air or air and fuel is compressed.
       Air charging in two-stroke designs is often  accomplished by means of
a low-pressure blower, which also aids in purging the exhaust gases;  such
systems are called blower-scavenged.  Naturally aspirated  and turbocharged
(or supercharged) systems are also common.
       The main  advantage of two-stroke engines is  their horsepower-to-weight
ratio as compared to four-stroke prime movers when  both operate at the  same
speed.  This is,  of course, due to the fact that the two-stroke design  has
twice as many power strokes per unit time as the four-stroke.   In  addition,
if ports are used instead of valves, the mechanical design  of the  engine  is
                                   3-27

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                           EXHAUST VALUE

                                     -FUEL  INJECTOR
CO
i
CO
                               COMPRESSION
COMBUSTION
                                                                                POWER STROKE
                                                 SCAVENGING
                        A.  INTAKE PORTS COVERED   A.   FUEL ENTERS CYLINDER   A .  PISTON MOVES DOWN  A.  AIR BLOWN INTO CYLINDER
                                                     BY INJECTION
                        B.  EXHAUST VALVE CLOSES                            B.  POWER DELIVERED    B.  EXHAUST GASES PURGED
                                                 B.   COMBUSTION BY AUTO-        TO CRANKSHAFT
                                                     IGNITION
                          Figure 3-7.  Cylinder events for a  two-stroke blower-scavenged  1C engine.

-------
simplified.   However, combustion cannot be controlled as well, and excess air
is needed to purge the cylinder.  Therefore,  these engines tend to be
slightly less efficient, and uncontrolled models tend to emit slightly more
pollutants (primarily unburned hydrocarbons), than do their four-stroke
counterparts(41).
3.2.2  Emission Sources and Types in 1C Engines
       Most of the pollutants from 1C engines are emitted through the
exhaust.  However, some hydrocarbons escape from the crankcase as a result of
blowby (gases which are vented from the oil pan after they have escaped from
the cylinder past the piston rings) and from the fuel tank and carburetor
because of evaporation.™/  Nearly all of the hydrocarbons from diesel
(compression ignition) engines enter the atmosphere from the exhaust(43).
Crankcase blowby  is minor  (0.18 g/hp-hr HC + NOX, 0.0063 g/hp-hr CO) because
hydrocarbons are  not present during compression of the  charge(44,45).
Evaporative  losses are  insignificant in diesel engines  due to the low
volatility of diesel fuels(46).   In general, evaporative losses are also
negligible  in engines using gaseous fuels  because these engines receive  their
fuel continously  from a pipe rather than via a fuel  storage  tank  and fuel
pump(47).   In gasoline-fueled engines, however, 20 to 25 percent  of the  total
hydrocarbon  emissions from uncontrolled engines come from crankcase blowby
and  another  10 to 15 percent from evaporation of  the fuel  in  the  storage  tank
and  the  carburetor  (divided approximately  equally between the two)(48).
-/Until  recently  it  was  thought  that  HC  evaporative  controls  on automobile
   fuel  tanks  and  carburetors  reduced  emissions  from  these  sources  to about
   5 percent of  the uncontrolled  levels.   However,  further, more comprehensive
   testing  has shown  that controlled vehicles  actually allow HC to  be
   evaporated  at approximately 70 percent of the rate from  uncontrolled
   cars  (42).
                                    3-29

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 However,  crankcase  blowby  emissions  can  be  virtually eliminated  through  the
 simple expedient  of  the  positive  crankcase  ventilation  (PCV)  valve.
       The  primary  pollutants from internal  combustion  engines are oxides  of
 nitrogen  (NOx). hydrocarbons  and  other organic  compounds  (HC), carbon
 monoxide  (CO),  and  particulates,  which include  both  visible  (smoke)  and
 nonvisible  emissions.  NOx formation is  directly related  to  high  pressures
 and temperatures  during  the combustion process  and to the nitrogen content  of
 the fuel.   The  other pollutants,  HC, CO,  and smoke,  are primarily the result
 of incomplete combustion.  Specific descriptions of  these formation
 mechanisms  in SI  and CI  engines are discussed in Chapter  4.   Ash  and metallic
 additives in the  fuel also contribute to  the particulate  content  of the
 exhaust, but usually do  not cause the exhaust to be  visible.  Although the
 odor of the exhaust  (primarily a  problem  with diesels) is believed to be the
 result of some organic compounds  in this exhaust (particularly aldehydes),
 a precise relation has not yet been established between exhaust and
odor(49-52).  Considerable research has  led to the belief that aldehydes may
 be one cause of odor in diesel and gasoline exhaust.   Aromatic hydrocarbons
 and other unburned elements of fuel,  as well as  sulfur species,  may also be
 a source of odor(53).
       Oxides of sulfur,  lead, and other metals  also  appear in the exhaust
from 1C engines.  The sulfur compounds, mainly S02,  are directly related to
the sulfur content of the fuel.   Most of  the metals  are fuel  additives and
generally leave the engine as  particulates.   Lead is  commonly added to
gasoline lines as an antiknock agent.  However,  laed-free gasoline is now
available nationwide, and leaded gasoline may not be  marketed in quantity in
the future.   Although various  metals, particularly barium, are sometimes
added to diesel fuel as a smoke  suppressant, their use is not recommended by
                                   3-30

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most engine manufacturers because of possible adverse effects on the engines
and on the environment(54,55).
3.2.2.1  Emission Characteristics -- Spark Ignition Engines
       Typical uncontrolled emission rates (23-mode composite)(56) for four-
stroke naturally aspirated gasoline engines in g/brake hp-hr  are:  2.4 to
13.1 for HC; 30.4 to 89.8 for CO; and 7.9 to 13.9 for N0x(57)-  Similarly,
brake specific emission rates from all types of spark-ignited gas engines
(two- and four-stroke, naturally aspirated and turbocharged engines) are:
0.4 to 1.9 for HC; 0.2 to 0.6 for CO; and 15.0 to 32.0 for NOX(58).
       Hydrocarbon emissions from these engines may be partially burned  or
completely unburned.  Three general mechanisms are believed to be the cause
of these pollutants(59).  The first, wall quenching, arises when fuel
droplets impinge on the cylinder walls and are cooled below the  ignition
temperature.  Whether the hydrocarbons remain unburned or are partially
oxidized depends upon the wall temperature, the droplet temperature  at
impingement, and the combustion  intensity nearby.  The second source of  HC
emission, incomplete combustion, can be caused by one, or more,  of the
following:
       a.  Change in charge homogeneity
       b.  Incorrect air-to-fuel ratio (too rich or too lean)
       c.  Low temperature of the incoming air-fuel mixture
       d.  Failure of the engine to purge all the products of combustion
       e.  Defective ignition system
       Scavenging, or the displacement of exhaust gases in the cylinder  by  a
fresh charge of air or air and fuel, is the third mechanism resulting in HC
emissions.  It is especially  a factor in carbureted two-cycle engines, where
                                    3-31

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part of the  Intake charge  1s  swept out with  the  exhaust  completely  escaping
the combustion process.
       Carbon monoxide emissions  are  also  related  to  Incomplete  combustion.
CO 1s formed during combustion and then normally combines with oxygen  atoms
(dissociated oxygen molecules) to form COg,  the  final  product.   This  last
reaction can only proceed  at  a high temperature  (above 90QOK)(60).  Therefore,
1f the overall mixture 1s  rich or if  sufficient  oxygen is not available
during and after combustion,  before the products of combustion cool below
900QK, CO will be formed.  Thus, both CO and HC  are due  to  improper air-fuel
mixing and Improper introduction Into the  chamber.  Their generation  is  also
a measure of the Inefficiency of the  combustion  process.
       NOx formation, on the  other hand, Increases with  Increasing  combustion
efficiency.  Its generation is governed by the pressure, temperature and
oxygen concentration during combustion.  Nitrous oxide (NO) is generated 1n
the cylinder when both the N2 and the 02 molecules dissociate into  free  atoms
at the high temperature encountered during combustion, and then  recombine to
form NO.  The reaction rate toward NO increases  exponentially with
temperature.   Maximum temperatures occur when the  air-to-fuel ratio is just
above stoichiometric.  NOa and other NOX compounds form  later in the presence
of additional oxygen.  NOx emissions are particularly high from  gas engines,
which burn fuel with an excess of oxygen.   In any  engine, as the air-to-fuel
ratio decreases from stoichiometric, NOx formation decreases because of  a
lack  of excess oxygen.  As the air-to-fuel  ratio increases from
stoichiometric, NOx formation first increases due  to the presence of more
oxygen.  Further increases in air flowrate cause a decline in peak combustion
temperature and a consequent decrease in NOx formation (Figure 3-8)(61).
                                   3-32

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        Visible emissions (smoke) are generally insignificant in gasoline and
 gas engines.  Particulates, however, may be present, especially as a result
 of rich fuel mixtures or impurities in the fuel.   On a mass basis, the
 majority of particulate emissions from gasoline engine exhausts are now the
 result of lead in  the fuel(62).   when smoke is present, particulate levels
 are high, but the  converse  does  not necessarily hold;  significant quantities
 of non-light-scattering particulates can be emitted in the absence of visible
 emissions.   The  bluish smoke that is sometimes observed,  particularly 1n
 older,  poorly maintained engines, is caused by Incomplete combustion  of
 crankcase or lubricating oil  which  is  forced  past  worn  piston  rings Into the
 cylinder.

 3.2.2.2   Emission  Characteristics -- Compression Ignition Engines
       As mentioned previously,  essentially all the  pollutants  from diesel  or
 dual-fuel engines  are  emitted through  the exhaust  (I.e.,  evaporative  and
 crankcase ventilation  emissions  are  negligible).   Again HC,  CO, NOX and
 particulate  matter  are  the  pollutants  of major  concern.   The formation  of
 these pollutants is complex  and  not  completely  understood.   Typical emission
 rates (specific) for all types of uncontrolled  diesel engines  (including
 four-stroke,  either naturally aspirated or  turbocharged and  open-  or  divided-
 chamber, and  two-stroke, either  blower-scavenged or turbocharged)  in  g/brake
 hp-hr are:  0.1 to 2.9 for HC; 0.3 to  14.6  for CO;  and 2.1 to 17.1 for
 NOX(63)-   Unburned  and partially  burned hydrocarbons are formed in CI engines
 by many of the same mechanisms that  contribute to their generation  in SI
 engines.   There are, however, two major differences:  the fuel  injection
system and the combustion chamber design.   Fuel is introduced into the
cylinder of a CI  engine by a fuel injector,  independently of the air,  whereas
                                   3-34

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 a fuel  and  air mixture  generally  is  allowed  to  flow  into  the  cylinder  of  an
 SI engine through the intake valve or port.  Therefore, the fuel-air mixture
 in a CI engine is heterogeneous by design.   However,  the  fuel  distribution
 within  the  cylinder can be controlled somewhat  by the design  of the injector,
 and therefore, both wall quenching and  large-scale  inhomogeneities can  be
 minimized(64,65).  Hence, both the fuel  injection system  and  the  combustion
 chamber design are major factors  which  determine the  quantity of  HC
 emitted(66,67).
        Since the carbon monoxide  results from incomplete  combustion in  the
 absence of  sufficient oxygen, and since  CI engines  are designed to operate
 lean (excess air), CO emissions are  usually  low.
       Conditions within the cylinder of a CI engine  during combustion  favor
 the production of NOXj because it is formed  at  high  temperatures  and
 pressures in the presence of oxygen.  However,  high temperatures  and
 pressures lead to high thermal efficiency (low  fuel consumption)  and high
 air-to-fuel ratios lead to low smoke, HC, and CO generation(68,69).
Therefore,  design compromises are usually required when an attempt is made to
 reduce or limit NOX emissions.
       Smoke occurs in three forms:   white (cold) smoke,  blue, and black (hot
 smoke)(70).  The white smoke consists primarily of unburned liquid fuel or
 lubricating oil and occurs at low load or idle  conditions.  Blue  smoke  is
caused by lubrication oil  that leaks into the combustion  chamber.  Black
smoke consists of carbon particles that result  from incomplete combustion at
high temperatures.   Incomplete  combustion is possible under high  loads  (low
air-to-fuel ratio)  and poor mixing of the fuel-air mixture.  Emission rates
of white and blue smoke are usually not measured by manufacturers.  They
generally report  black smoke emission rates  of  less than  10-percent opacity
                                   3-35

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 (1.18 milligrams  per  cubic foot  for a 16-inch  diameter stack)  for a well
 maintained  engine!71-73).

 3.2.2.3   Effects  of Variables  on Emissions
       Many variables  affect emissions  from 1C  engines.   Table 3-3(74)  lists
 these variables,  divided  into  three categories.   Those listed  as  "Design"  are
 features  that  are  normally determined  by  the manufacturer.   The "Operation
 Adjustment"  category  represents  variables that  can  be  altered  by  the user.
 Since these variables  can  be adjusted  to  reduce  emissions,  they are discussed
 1n more detail  1n  Chapter  4, Emission  Control Techniques.   The last column
 lists those  variations  1n  ambient air  conditions which affect  emissions.
 3.2.2.3.1   Size
       Engine  size has  a definite effect  on  emissions.   Large-bore,  low- to
 medium-speed engines,  independent of the  fuel type  (diesel,  dual  fuel,
 natural gas),  have certain  common emission  characteristics.  These  large-bore
 engines are  designed for low fuel consumption (i.e., high thermal
 efficiency).   Furthermore,  their  low rotational  speed  maintains the  products
 of combustion  near peak temperature for relatively  long  periods of  time.
 These  slow  speeds  allow the designer to "tailor"  his fuel injection  schedule
 for optimum  results, and the large  combustion volumes  also  give him  more
 aerodynamic design freedom  than  is  available to  the manufacturer  of  small- or
medium-bore engines(75).  Furthermore, these large  engines  are  designed to
 operate under steady conditions  and almost  always at more than  50 percent  of
 rated power; therefore, they do not have to  contend with acceleration/
 deceleration or low power requirements(76,77).
                                    3-36

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   TABLE 3-3.   FACTORS THAT AFFECT EMISSIONS FROM RECIPROCATING ENGINES
                                                                       (74)
         Design
     Operation Adjustment
 Ambient Conditions
Surface to volume ratio
Bore and stroke
Valve overlap
Displacement/cylinder
Strokes/power cycle
Chamber design
Compression ratio
Air charging:
  Naturally aspirated
  Blower scavenged
  Turbocharged
Fuel charging:
  Direct injection
  Indirect injection
  Carbureted
Engine cooling
Air-to-fuel ratio
Torque (mean effective
pressure)
Speed
Spark timing
Fuel injection timing
Fuel properties
Lubrication and maintenance
Pressure (altitude)
Temperature
Humidity
                                  3-37

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 3.2.2.3.2  Load and Alr-to-Fuel Ratio
        Load and air-to-fuel  (A/F)  ratio variations have a significant effect
 °n NOX, CO, HC, and parti oil ate emissions.   In general, diesel compression
 ignition engines exhibit decreasing brake specific emissions of NOx w1tn
 increasing load (i.e.,  the  lower A/F ratio  and higher power output overcome
 the potential  for increased NOx production  due to  higher temperatures)(78).
 CO emissions  first decrease with increasing load  (equivalent to increasing
 temperature)  and then increase  dramatically as maximum load is approached.
 Incomplete combustion with the  decreasing A/F  ratio (increasing load) is
 largely responsible for  the final  trend reversal.   Brake specific  HC
 emissions,  likewise, decrease with  increasing  load as  a result of  Increasing
 temperature(79).   Small  (less than  15 hp) SI engines  (gasoline)  exhibit
 relatively high  HC and CO emissions, particularly  at  low load  operation(80),
        Figure  3-8  Illustrated the effect  of A/F ratio  upon  emissions  from
 spark  Ignition  engines.  NOX and CO  emissions  are  very definitely  related  to
A/F ratios.  These  trends hold  throughout the  load  range for an  SI  engine.
 Note that  an engine whose A/F ratio  is  adjusted to  yield lowest  HC  and CO
 emissions  has  a maximum  NOx emission.   An uncontrolled  engine  that  is
 adjusted to near-stoichiometric conditions  will emit relatively  large
quantities of N0x» whereas one that  is  run  either  lean  or rich will produce
significant quantities of HC and CO  (assuming  other modifications or  control
technologies are not applied to control HC  and CO).
3.2.2.3.3  Climate and Location
       All  the effects  of variations in climate and geographic location on
emissions are reflected  by changes  in the pressure, temperature, and humidity
of the ambient air.  Pressure  and temperature variations alter the density of
                                   3-38

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the inlet air charge and, hence, change the air-to-fuel  ratio.   (The
consequences of changing A/F ratio have just been discussed.)  Secondarily,
they change the peak combustion pressure and temperature  in proportion  to
their variations in the ambient air.  Since NOx production is a  strong
function of temperature, variations of the inlet air temperature  have a
noticeable effect on NOx emissions.  In general, humidity has little effect
upon HC and CO emissions(81,82).  NOX emissions, however, are significantly
affected by humidity variations because the water absorbs some of the heat
generated during combustion, thereby reducing the peak combustion
temperature.  Although the qualitative effects of varying ambient conditions
of emissions are known, a reliable quantitative relationship exists only for
the effects of humidity on NOx production from vehicular gasoline and diesel
engines(83,84).  Since these relationships are based on experiments, and
cannot be predicted analytically, they are applicable only to stationary
engines which are similar to vehicular models.  Similar relationships have
not yet been developed for high-power, low- and medium-speed engines.   Since
the combustion characteristics of these large engines are different than
those of the vehicular size units,  there is no a priori justification for
applying the above-mentioned relationship to the larger engines.
3.2.2.3.4  Fuel Effects
       Significant variations in the emissions of reactive HC may be due to
the fuels used.  As mentioned previously, HC emissions from SI gasoline
engines originate from the fuel system through evaporation, from the exhaust
due to combustion,  and from crankcase blowby.   In general, fuel  evaporation
1s proportional to fuel volati!1ty(85).   Effective systems are now used to
control  evaporative emissions and crankcase blowby on automobiles.  Studies
                                   3-39

-------
have shown that exhaust HC emissions from unleaded fuels have a higher
photochemical reactivity than do those from base leaded fuels, assuming no
catalytic converters are used(86).
       Diesel fuels used 1n CI engines may display some variation 1n density
and viscosity which, 1n turn, affects the A/F ratio and fuel spray pattern 1n
the cylinder.  If only a single fuel 1s used, the engine 1s "tuned" for 1t,
but 1s 1s unlikely that engines would be "retuned" for each fuel if fuel
types were frequently changed.
       Particulate and smoke generation tends to Increase with Increasing
Cetane number.  The relationship between smoke and fuel volatility 1s unclear
because It 1s difficult to separate the effects due to volatility changes
from those due to Cetane number(87).

3*2«3  State and Local Regulations
       Most states and localities restrict visible emissions from stationary
sources,  Including reciprocating Internal combustion engines, to less than
20-percent opacity and many are now requiring that plumes from new Installa-
tions have less than 10-percent capadty(88).  These limits usually do not
present a problem to the owner who operates and maintains his engine
correctly.  However, since many NOX control systems tend to increase smoke,
engines may not be able to meet these opacity limits if very stringent NOx
standards are proposed.
       The only known restrictions on gaseous emissions from reciprocating 1C
engines (I.e., excluding gas turbines,  which  have been specifically regulated
by some localities) are 1n the Los Angeles area.   Several  control  districts
1n this basin limit NOX emissions (expressed  as N02) to 140 Ib/hr (63.5
kg/hr)(89-91).  Typical uncontrolled engines  emit 10 to 20 g/hp-hr (see
                                   3-40

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                          REFERENCES  FOR  CHAPTER 3

 (1)  Of fen, G. R.  (Aerotherm/Acurex) ,  meeting at  EPA  (Durham) with E M A
 Members, Interoffice Memorandum,  November 26, 1974.

 r«LiSleS?Q7fr^f-  Tur^'?e Pr°9ress." Diesel and  Gas Turbine Worldwide
 Catalog, 1974 Edition,  Milwaukee,  Wisconsin.

 (3)  Offen, G. R.  (Aerotherm/Acurex),  Trip  Report, August 30, 1974.

 (4)  Offen, G. R.  (Aerothertn/Acurex),  Trip  Report, July 26, 1974.


                                                and "• R- Goodwin
 (7)   Offen,  G.  R.  (Aerotherm/Acurex), Trip Report, July 26, 1974.

 (8)   Offen,  G.  R.  (Aerotherm/Acurex), Trip Report, August 30, 1974.

 (9)   Internal Combustion Engines, Current Industrial Reports, U.S.

 No5embeM974 C0imerce' Bureau of Census' Washington, D.C., MA-35L(73)-1 ,


 (10)  Hanley, G. P. (General Motors Corporation) and D.  R.  Goodwin  (EPA)
 private communication, January 24, 1975.


 (11)  Henderson, R. D. (Caterpillar)  and  R.  D.  Seiffert  (EPA),  private
 communication, December 19, 1974.


 (12)  Basiletti, J. C. (International Harvester) and D.  R.  Goodwin  (EPA)
 private communication, November 12, 1974.


 DecemberS14ani974 H' (FOrd) "^ °'  R< G°°dwin (EPA)>  pn'Vate  cormuni'cation,


 (14)  Taggert, J. C. (White Engine Co.  —  Hercules)  and  R.  D. Seiffert  (EPA)
 private communications, January 22,  1975.

 (15)  Requeiro,  J.  F.  (Teledyne Continental)  and D.  R. Goodwin  (EPA)
private communication, November 19,  1974.


 (16)  Houston, G. (Briggs  and Stratton  Corporation)  and  R.  D. Seiffert  (EPA)
private communication, December 3,  1974.

 (17)  Cox,  N. S.  (Waukesha-Dresser),  Data, April  16,  1975.

 (18)  "A Study of Markets  for Natural Gas  Engines," American Gas Association,
Arlington,  Virginia, Catalog  No. 60100, January  1970.
                                    3-42

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  (19)  McGowin, C. R., "Stationary Internal  Combustion Engines  in  the  United
  States," Environmental Protection Agency, EPA-R2-73-210,  April  1973.

  (20)  Preliminary 1973 Power Production and Fuel  Consumption Data," Federal
  Power Commission News Release No. 20333, Washington,  D.C.  p. 7, May 24, 1974.

  (21)  "Gas Facts - 1972."  Department of Statistics,  American Gas Association
 Arlington, Virginia.  1973.


  (22)  "1974 Report on Diesel  and Gas  Engine Power Costs,"  American Society
 of Mechanical Engineers,  New York,  New York,  1974.

 (23)  "Principle Machines on Farms  —  1973,"  Implement and Tractor, p. 40,
 November 21,  1973.


 (24)  Urban,  C.  M.  and K.  J.  Springer,  "Study of  Exhaust Emissions from
 Natural  Gas Pipeline Compressor  Engines," Southwest Research Institute,
 PR-15-61,  February  1975.


 (25)  "Internal  Combustion Engines," U.S. Department of Commerce, Bureau of
 Census,  Washington,  D.C.,  MA-35L(73)-1,  November  1974.

 (26)  "Construction  Machinery,"  U.S. Department of Commerce, Bureau of
 Census,  Washington,  D.C.,  MA-35D(72)-1,  February  1975.

 (27)  "Pumps  and  Compressors," U.S. Department of Commerce, Bureau of  Census,
 Washington, D.C., February 1975, MA-35P(73)-1.                        ^n*ub,

 (28)  "Motors and Generators," U.S. Department of Commerce, Bureau of  Census,
 Washington, D.C., MA-35H(73)-1,  July  1974.

 (29)  "1967 Census of Manufacturers: Engines, Turbines, Farm Machinery and
 Equipment," U.S.  Department of Conmerce, Bureau  of Census, Washington, D.C.,
 MC-67(2)-35A, September 1970.

 (30)   Youngblood, S. B. (Aerotherm/Acurex) and P.  Dawson (Ford),  private
 communication, October 2,  1974.

 (31)   Youngblood, S. B. (Aerotherm/Acurex) and H.  Colby (George  Engine Co,,
 Morgan, Louisiana) and Mr. Manning (Stewart-Stevenson,  Houston, Texas),
 private comnunication, May 28, 1975.

 (32)  Youngblood, S. B. (Aerotherm/Acurex),  Mr.  Langley (Hobart Bros,  Troy,
 Ohio), and Mr. Hastings (Lincoln  Electric, Cleveland,  Ohio), private communi-
 cation, May 28, 1975.

 (33)  "A Study of the Markets  for Natural Gas  Engines," American Gas
Association, Arlington, Virginia, January 1970.

 (34)  "Federal Power Commission," Order from U.S.  Government Printing Office,
Stock No. 1500-00258.
                                     3-43

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(35)  Obert, E.  F.,  "Internal  Combustion Engines and Air Pollution," httext
Educational  Publishers,  New York,  1973.

(36)  Patterson, D.  J. and  N.  A. Henein, "Emissions from Combustion Engines
and Their Control,"  Ann  Arbor  Science,  1972.

(37)  Obert, E.  F.,  Reference  35,  p.  3.

(38)  Offen, G.  R.  (Aerotherm/Acurex) and  Dr. F. McNall (Dresser-Clark),
private comnunication, May  23, 1975.

(39)  Offen, G.  R.  (Aerotherm/Acurex),  Trip Report, August 30, 1974.

(40)  Offen, G.  R.  (Aerotherm/Acurex),  Trip Report, November 18, 1974.

(41)  Patterson, D.  J. and  N.  A. Henein, Reference 36, pp. 44-45, 117,
128-129.

(42)  Finke, E.  W.  (Source  Receptor Analysis  Branch, EPA) and D. S. Kircher
National Air Data Branch, EPA) to  B.  J. Steigerwald (Director, Office of Air
Quality Planning and Standards, EPA), private conmunication, February 3, 1975.

(43)  Patterson, D.  J. and  N.  A. Henein, Reference 36, p. 231.

(44)  Bosecker, R.  E. and D. F. Webster (Research Department, Caterpillar
Tractor, Co.), "Precombustion Chamber Diesel  Engine Emissions -- A Progress
Report," SAE Paper 710672,  August  1971.

(45)  Youngblood, S. B.  (Aerotherm/Acurex) and  G. P. Hanley, private
communication, May 19,  1975.

(46)  Bosecker, R.  E.,  et al, Reference 44.

(47)  Youngblood, S. B.  (Aerotherm/Acurex), F.  S. Schaub  (Cooper-Bessemer),
and N. S. Cox (Waukesha), private  communication, May 23,  1975.

(48)  Patterson, D.  J.  and  N. A.  Henein,  Reference 36, p. 197.

(49)  Savery C. W., Matula, R. A., and  Asmus, T., "Progress  in Diesel Odor
Research,"  SAE Paper 740213, February 1974.

(50)  Springer, K. J. and C. T. Hare, "Four Years of Diesel  Odor and Smoke
Control Technology Evaluations --  A Summary," ASME Paper  69-WA/APC-3,
August  1969.

(51)  Springer, K. J. and R. C. Stahman,  "Control of Diesel  Exhuast Odors,"
Conference  on Odors, The New York  Academy of  Sciences, New  York, New York,
Paper No. 26, October 1-3,  1973.

(52)  "Chemical Analysis of Odor Components  in  Diesel  Exhaust," Arthur  D.
Little  Report No. ADL 74744-5, September 1973,  EPA  650/2-73-025.
                                     3-44

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 (53)   Patterson,  D. J. and N. A. Henein, Reference 36, pp. 269, 270, 293.
 (54)   Durkee,  K.  R. (EPA), "Meeting with Manufacturers' Representatives of
 the Diesel  Engine Manufacturers Association (DEMA) at EPA (Durham)
 Meeting  Report, p. 7, September 3, 1974.
 (55)   Shaman,  E.  and T. 0. Wagner,(AMOCO), "Fuel Quality of Engine Design:
 Which  Controls Diesel Emissions?" SAE Paper 730168, January 1973.
 (56)   Hare, C. T. and K. J. Springer, "Exhaust Emissions from Uncontrolled
 Vehicles and Related Equipment Using Internal  Combustion Engines,  Part 5 --
 Heavy-Duty  Farm,  Construction, and Industrial  Engines," Southwest  Research
 Institute Report  AR-898, p. 17, Southwest Research Institute, San  Antonio,
 Texas, October 1973.
 (57)   Roessler, W. U., A. Muraszew, and R. D.  Kopa, "Assessment of the
 Applicability of  Automotive Emission Control  Technology to Stationary Engines,"
 EPA 650/2-74-051, Urban Programs Division, Aerospace Corporation,  El  Segundo,
 California, p. 3-55, July 1974.
 (58)   Roessler, W. U., et al., Reference 57,  p. 3-56.
 (59)   Patterson,  D. J. and N. A. Henein, Reference 36, pp. 117-131.
 (60)   Patterson,  D. J. and N. A. Henein, Reference 36, pp. 100-101.
 (61)   Roessler, W. U., et al., Reference 57,  p. 4-72.
 (62)   Patterson, D. J. and N. A. Henein, Reference 36, p.  64.
 (63)  Roessler, W. U., et al., Reference 57.,  p.  3-30.
 (64)  Obert, E. F., Reference 35,  p.  570.
 (65)  Patterson, D.  J. and N. A.  Henein, Reference 36, pp.  232-261.
 (66)  Obert, E. F., Reference 35,  p.  371.
 (67)  Patterson, D.  J. and N. A.  Henein, Reference 36, pp.  267-268.
 (68)  Obert, E. F.,  Reference 35,  pp.  369-372.
 (69)  Patterson, D.  J.  and N.  A.  Henein, Reference 36,  pp.  267-268.
 (70)  Obert, E. F.,  Reference 35,  pp.  271-272.
 (71)  Newton,  C.  L.  (Colt)  and G.  R. Offen  (Aerotherm/Acurex),  private
communication,  October 28,  1974.
 (72)  Offen, G.  R. (Aerotherm/Acurex), Trip Report, September 13, 1974.
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(73)  Shaw, J. (White Superior)  and J.  S.  Fletcher  (Aerotherm/Acurex),,
private corrmunication, November  14, 1974.
(74)  Patterson,  D.  J. and N.  A.  Henein, Reference  36, p. 143.
(75)  Offen, G.  R.  (Aerotherm/Acurex),  Meeting at EPA  (Durham) with E.M.A.
Members, Interoffice Memorandum,  p. 4,  November  26, 1974.
(76)  Offen, G.  R.  (Aerotherm/Acurex),  Reference 75, p. 5.
(77)  Durkee, K.  R.  (EPA), Reference 54, pp.  2,  4.
(78)  Roessler,  U.  U., et al., Reference 57,  pp. 3-25, 3-26, 3-27.
(79)  Ibid.
(80)  Hare, C. T.  and K.  J.  Springer, "Exhaust Emissions from Uncontrolled
Vehicles and Related Eqipment  Using Internal  Combustion Engines, Part 4 --
Small  Air-Cooled  Spark Ignition  Utility Engines," Southwest Research Institute,
San Antonio, Texas,  ATPD-1493, May  1973.
(81)  Patterson,  D.  J. and N.  A.  Henein, Reference  36, p. 173.
(82)  Krause, S.  R., D.  F. Merrion, and G. L. Green, "Effect of Inlet Air
Humidity and Temperature on Diesel  Exhaust Emissions," SAE Paper No. 730213,
1973.
(83)  "Federal Register," Volume  38, No. 224, November 21, 1973, Volume 39,
No. 40, February  27, 1974.
(84)  "Effect of Humidity of Air Intake on Nitric Oxide Formation in Diesel
Exhaust,"  Coordinating Research  Council, CRC  Report No. 447, December 1971.
(85)  Ellis, J.  C.,  "Gasoline  for Low Emissions Vehicles," SAE Paper No.
730616, SAE Transactions, Section 3, Volume 82,  1973.
(86)  Hurn, R. W.,  "Fuel:  A Factor in  Internal Combustion Engine Emissions,"
ASME Paper, 69-WA/APC-8.
(87)  Ibid.
(88)  Duncan, L.  J., "Analysis of Final State Implementation Plans -- Rules
and Regulations,"  EPA Publication APTD-1334,  July 1972.
(89)  "Rules and Regulations," Air  Pollution  Control District, Ventura,
California, Rule 59, p.  43,  August  1, 1974.
(90)  "Rules and Regulations," Air  Pollution  Control District, Riverside,
California, Rule 72, p.  43,  August  1, 1974.
(91)  "Rules and Regulations," County of Los  Angeles Air Pollution Control
District,  Los Angeles, California,  Rule 67.
                                     3-46

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                                CHAPTER 4
                        EMISSION CONTROL TECHNIQUES

       Stationary reciprocating 1C engines emit primarily NOX)  CO, HC, and
participates (see Section 3.2.2).  All  of these emissions are criteria
pollutants; that is, National Ambient Air Quality Standards (or maximum
allowable ambient concentrations) have been established for these pollutants
under Sections 108 and 109 of the Clean Air Act.  As indicated in Section
9.1, EPA has placed a high priority on the control of NOx emissions from
stationary sources since these emissions are projected to increase about 25
percent by 1985 despite the application of best available control technology
to new sources.  Moreover, NOX is the most significant pollutant emitted from
stationary 1C engines, accounting for more than 16 percent of the total NOx
emitted from stationary sources.  In addition,  as will be shown in Section
9.1, approximately 75 percent of the NOX emissions from installed stationary
reciprocating 1C engines (1974) was contributed by units larger than 500 hp.
This chapter, therefore, emphasizes the control of N0x» and control
techniques are discussed which have been applied, or can potentially be
applied,  to large,  stationary 1C engines.
       This chapter is divided into six sections.  The formation of the
pollutants emitted  by 1C engines is briefly discussed in Section 4.1  to aid
in understanding emissions control.   Section 4.2 discusses the  effect of
ambient conditions  (humidity, temperature,  and  pressure), and measurement
                                   4-1

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practices upon reported emission levels.   Specifically, Section 4.2.1
describes how ambient correction factors  will be used to adjust reported NOx
data to standard conditions, and Section  4.2.2 discusses and compares the
measurement practices of the manufacturers who reported emission data.  The
uncertainty of each stationary 1C engine  manufacturer's measurement practice
is estimated relative to EPA's proposed approach for 1979 and later model
heavy-duty diesel and gasoline engines.  These uncertainties will be used to
place boundaries on estimates of average  emissions from engines of the same
fuel type, but different manufacturer.
       Section 4.3 presents uncontrolled  (baseline) emission levels for large
stationary 1C engines.  In  addition to these data, sales-weighted averages of
uncontrolled NOx levels (by horsepower, excluding standby applications) will
be presented.
       Section 4.4 discusses specific control systems to reduce NOx
emissions.  The  discussion  considers  how each control  system works:  its
effectiveness, resulting fuel penalties,  effects on other emissions  (HC, CO,
smoke),  technical  limitations to its  application, and  cost  implications
(fuel, hardware, and maintenance).  The emission data  are corrected  to
standard  ambient conditions where possible  (see Section 4.2.1).
       Finally,  control systems for HC and  CO emissions are discussed  in
Section  4.5,  and techniques  to  reduce visible emissions are reviewed in
Section  4.6.  As stated in  Section 4.5, there has been  little  effort  by
manufacturers of large-bore engines  to reduce emission  rates of  HC  and CO
from their engines,  primarily because there  are currently no regulations
affecting these  emissions  and they are already  quite  low.   Moreover,  the
application  of NOx control  systems has, in  general, only a  small  effect on HC
and CO  levels  (see Section  4.4.12).   Furthermore,  several manufacturers  have
                                    4-2

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 achieved reductions in HC and CO  levels as a consequence of their efforts to
 reduce visible emissions and improve the fuel economy of their diesel
 engines.  These practices are discussed in both Sections 4.5 and 4.6.

 4.1    POLLUTANT FORMATION
        The combustion of fuel and air in the cylinder of a reciprocating
 engine results in the formation of a number of  chemical  compounds which can
 "cause or contribute to the  endangerment of public health or welfare" when
 emitted to the atmosphere.   The ones of  most  concern fall  into the general
 categories of nitrogen oxides (N0x)) carbon monoxide (CO),  sulfur oxides
 (S0x)> various hydrocarbons  and organic  compounds  (HC),  and  particulates.
 Additionally,  smoke and odorous fumes may  be  produced, chiefly in compression
 ignition  engines.   The following paragraphs  discuss  the  formation of  these
 pollutants  in  stationary reciprocating 1C  engines.

 4.1.1   Nitrogen Oxides (NOX)
        Virtually  all NOX  emissions  originate  as  nitric oxide  (NO)  resulting
 from oxidation of nitrogen during  the  combustion process.  Both N2 and  02
 dissociate  into atomic N  and 0,  respectively, at the  pressures  and
 temperatures encountered  in the  cylinder.  These atoms combine to form  NO,
 part of which  is then  further oxidized in the engine  and exhaust  system  to
form N02-  Tne remaining NO is exhausted into the atmosphere, where, in the
presence of additional oxygen, it also reacts rapidly to form the more stable
N02-  The N02 molecules, however, can be  dissociated by ultraviolet light
from the sun.   Additional reactions  involving the ultraviolet light from the
sun, nitrogen  and  hydrocarbon effluents,  and atmospheric  oxygen produce
polynuclear aromatics and other  components  of photochemical  smog.
                                   4-3

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       Most of the nitrogen enters  the  engine as  molecular  N2  in  the  air,
since natural gas and the premium distillate fuels  generally used in
reciprocating engines contain little fuel-bound nitrogen.   Oxides of  nitrogen
that come from N2 in the air are called thermal NOx-   However,  the heavier
oils, such as residuals and crudes,  contain significant quantities of
nitrogen (e.g., up to 1 percent).  When these fuels are used,  as  is
occasionally done in large diesel engines,  noticeable amounts  of  "fuel", or
"organic", NOx are generated.  The degree of oxidation of the  nitrogen in the
fuel appears to be primarily a function of its nitrogen content.   For gas
turbines, several researchers have found that the fraction of  fuel-bound
nitrogen converted to NO decreases with increasing nitrogen content,  although
the  absolute magnitude of the NO formed increases (1,2).  For  example, a low
nitrogen fuel  (0.01  percent) may have 100 percent of the fuelbound nitrogen
converted to NOX> whereas a  high nitrogen fuel (1.0 percent) may have only 40
percent  of  it  reacted  to NOX.  Consequently, when residual oil is burned in
turbines, more NO is produced from fuel-bound  nitrogen than from N2 present
in  the  air(3).
        Similar data  are  not  available for reciprocating engines.  However,
the relative magnitudes  of  thermal  and fuel  NOX  are quite  different for
reciprocating  engines  than  for  turbines because  the engines generate about  10
times more  thermal  NOX than  do  the  turbines.   Thus,  if  the  fuel  for  an  engine
contained 1-percent  nitrogen,  and  all  of this  were converted to  oxides  of
nitrogen,  the  exhaust  would contain about  5  g/hp-hr N02.   By comparison,
 uncontrolled large-bore diesel  engines  emit  7.5  to 18.7 g/hp-hr  when  using
distillate (No.   2)  containing about 0.03-percent  nitrogen(4).
        All  data  presented in this  document  on  emissions from  diesel  and dual
 fuel engines are based on operation with No. 2 distillate  (diesel  oil).  The
                                    4-4

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possible effects of any of the controls to be discussed in this chapter on
the fuel-bound nitrogen are not known.   Naturally,  denitrification of  the
fuel prior to its use will reduce the potential  NOX emissions,  and this
"control" is discussed briefly in conjunction with  fuel desulfurization (see
Section 4.4.13).
       The rate of formation of thermal NO is a function of the residence
time of the atomic nitrogen with atomic oxygen at elevated temperatures.   The
minimization of any or all of these three underlined variables  forms the
basis for almost all successfully demonstrated NOX  control methods.  Although
exhaust treatment of the NO via catalytic converters has been  proposed and
tested for gasoline-fueled automobiles, research into its applicability to
diesel and large natural gas engines is just reaching the experimental
stage(5,6).  This subject is treated in more depth  later (Section 4.4.9).
4.1.2  Hydrocarbons (HC)
       The pollutants commonly classified as hydrocarbons are  composed of a
wide variety of organic compounds.  They are discharged into the atmosphere
when some of the fuel remains unburned or is only partially burned during the
combustion process.
       Most unburned hydrocarbon emissions result from fuel droplets  that
were transported or injected into the "quench layer" during combustion.  This
is the region immediately adjacent to the combustion chamber surfaces,
where heat transfer outward through the cylinder walls causes  the mixture
temperatures to be too low to support combustion.
       Partially burned hydrocarbons, on the other  hand, can occur for a
number of reasons(7,8):
                                   4-5

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       t   Poor air-fuel  homogeneity due to incomplete mixing prior to,  or
           during, combustion (i.e., local  zones that are too rich or too
           lean).   The most common cause of this is improper maintenance or
           design  of the  fuel handling system.
       •   Incorrect air-fuel ratios in the cylinder during combustion (i.e.,
           the entire cylinder is  too rich  or too lean) due to maladjustment
           of the  engine  fuel system.
       t   Excessively large fuel  droplets  (diesel  engines).  This is
           generally the  result of worn, clogged, or poorly designed
           injectors and/or low injection pressures.
       •   Low cylinder temperature due to excessive cooling through the
           walls or early cooling  of the gases  by expansion of the combustion
           volume  caused  by piston motion before combustion is completed.
           This condition commonly occurs in engines that have faulty
           temperature control systems or have  excessively delayed ignition.
       All of these conditions can be caused by either poor maintenance  or
faulty design.  Therefore, the lowest emissions will be achieved only by
proper maintenance of engines designed specifically for low emissions.
4.1.3  Odor
       Odor in the exhaust is primarily a problem with diesel engines.
Although the smell  is believed to be from some of the hydrocarbons in the
exhaust, a precise relation has not yet been established between exhaust and
odor(9,10,ll).  Considerable research has led to the belief that aldehydes
may be one cause of odor  in diesel  (and gasoline) exhaust.  Aromatic
hydrocarbons and other unburned elements of fuel, as well as sulfur species,
may also be a source of odor(12).
                                   4-6

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       Subjective evaluation of automobile diesel odors has shown that in-
stalling sac injectors (see Section 4.5) and catalytic mufflers for
hydrocarbon control also reduces odor levels(13).
       Standards for odor are not being developed at this time because odor
levels are low in the vicinity of large-bore engines (in part due to their
relatively tall stacks), no control technology has been demonstrated
specifically for odors, and no readily implemented method exists for
measuring odor levels.
4.1.4  Carbon Monoxide (CO)
       Carbon monoxide is an intermediate combustion product that appears in
the exhaust when the reaction of CO to C02 cannot proceed to completion(14).
This situation occurs if there is a lack of available oxygen, if the gas
temperature is too low, or if the residence time in the cylinder is too
short(15).  The oxidation rate of CO is limited by reaction kinetics and, as
a consequence, can be accelerated only to a certain extent by improvements in
air-fuel  mixing during the combustion process(16).
4.1.5  Smoke and Particulate Matter
       White,  blue, and black smoke may be emitted from 1C engines.  Liquid
particulates appear as white smoke in the exhaust during an engine cold
start, idling, or low load operation.  These are formed in the quench layer
adjacent  to the cylinder walls,  where the temperatures are not high enough to
ignite the fuel.   They consist primarily of raw fuel with some partially
burned hydrocarbons and lubricating oil(17).   White smoke emissions are
generally associated with older  gasoline engines and are rarely seen in the
exhaust from diesel or gas-fueled units.   They cease when the engine reaches
                                   4-7

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its normal operating temperature and can be minimized during low demand
situations by proper idle adjustment.
       Blue smoke is emitted when lubricating oil  leaks,  often past worn
piston rings, into the combustion chamber and is  partially burned(18).
Proper maintenance is the most effective method of preventing these emissions
from all types of 1C engines.
       The exact formation mechanisms of black smoke are still not fully
understood, although a number of models and theories have been offered  to
explain its formation in diesel engines(19,20).   it is generally agreed,
however, that the primary constituent of black smoke is agglomerated carbon
particles  (soot).  These form in a two-step process in regions of the
combusting mixture that are oxygen deficient(21).   First the hydrocarbons
decompose  into acetylene and hydrogen in the high  temperature regions of the
cylinder.  Then, when the local gas temperature drops as the piston moves
down and the gases expand, the acetylene condenses and releases its hydrogen
atoms.  As a result, pure carbon particles are created.  This mechanism of
formation  is associated with the low air-to-fuel  ratio conditions that
commonly exist at the core of the injected fuel spray, in the center of large
individual fuel  droplets, and in fuel layers along the walls!22).  The
formation  of particules from this source can be reduced by designing the fuel
injector to provide for an even distribution of fine fuel droplets such that
they do not impinge on the cylinder walls.
       Once formed, the carbon will combine with oxygen to form CO and C02 if
it is still at an elevated temperature.  Since the temperature of the exhaust
system  is  too low for this oxidation to occur, soot that  leaves the
combustion chamber before it has had the opportunity to oxidize completely
will be discharged as visible particles.
                                   4-8

-------
        Becauase soot formation  is  very  sensitive  to  the  need  for oxygen,  Its
 discharge is greatest when  the  engine is  operating at  rich  fuel/air  ratios,
 such as at rated power and  speed.   Therefore,  naturally  aspirated engines
 are likely to have higher smoke levels  than  turbocharged engines, which
 operate at leaner fuel/air  ratios.

 4.1.6  Sulfur Dioxide ($02)
        Sulfur dioxide emissions are a function of only the  sulfur content in
 the fuel  rather than of  any  combustion  variables.  In fact, during the
 combustion process essentially  all  the  sulfur  in the fuel is  oxidized to
 S02-1/   Manufacturers of  diesel  engines currently recommended that users burn
 only fuels which contain  less than  0.5  percent sulfur(23).2/  This practice
 is  suggested to minimize  corrosion,  but it also results  in S02 emission
 levels  of  less  than  2 g/hp-hr from  most internal combustion engines.V
 Nevertherless,  fuel  sulfur content may  range as high as  1.0 percent according
 to  ASTM fuel  specifications  for No.  2 or No. 2D distillate o1ls(26).   These
 distillates  are the  fuels most  commonly burned in stationary,  large-bore
 diesel  engines.  The  refining of crude oil into the No.  1 and No.  2 distillate,
I/Presumably the ratio of S03 to S02 in tne exhaust of 1C engines is a
  function of the combustion process, as it is in boilers.  Data are not
  available to clarify this question, and in any case, the total sulfur
  emitted is equal to the sulfur contained in the fuel.
£/This level, which corresponds to approximately 0.7 Ibm/MBtu based on heat
  input, is nearly one-half the value specified in the standards of perfor-
  mance for new oil-fired steam generators (1.2 Ibm/MBtu, assuming 40 per-
  cent efficiency)(24).   Existing steam plants average 3.0 to 5.0 Ibm/MBtu
  heat input (equivalent to 8.7 to 14.4 g/hp-hr output)(25).
^/For example,  an engine firing 0.5 percent sulfur No.  2 distillate at a rate of
  0.4 Ib/hp-hr would emit 1.8 g/hp-hr of S02>  assuming all the sulfur in the
  fuel is converted to S02.
                                     4-9

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data to standard conditions of humidity and temperature)  and measurement
procedures be adopted by manufacturers  of diesel  and  gasoline engines whose
emissions are regulated under Title II  of the Clean A1r Act.   For  the same
reasons, ambient correction factors should be used when analyzing  emissions
data from stationary 1C engines.   Likewise,  consideration should be  given  to
potential impacts on the certainty of the data due to the measurement
procedures used.
       To this end, Section 4.2.1  briefly reviews  the effect of  ambient
conditions on the reported NOX data and then recommends ambient  correction
factors appropriate for stationary 1C engines.  Section 4.2.2, in  turn,
discusses and compares the four different measurement practices  used by the
nine manufacturers of large-bore  stationary 1C engines.  Estimates of
uncertainty for three of the practices  (relative  to the EPA procedure) are
given for the manufacturers who did not follow the EPA practice.   These
estimates will be used to determine the uncertainty in average emission
levels that were computed from data provided by the manufacturers.

4.2.1  Effect of Ambient Humidity, Temperature,  and Pressure
       EPA has adopted ambient correction factors  for regulated mobile
sources, based on experimental studies(27,28).   These factors are  used to
correct observed NOx levels to values at a standard temperature  (850F) and
humidity (75 grains H20/lb dry air) for heavy duty (HD) diesel engines and to
correct to standard humidity,  only, for both heavy and light  duty  gasoline
vehicles(29,30).  HC and CO emissions from both CI and SI engines  are also
sensitive to ambient humidity, temperature,  and  pressure.  One study  of diesel
engines established that variations in  humidity did not affect HC, CO, or
smoke levels(31).  Temperature variations,  however, did substantially affect
                                   4-11

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 HC,  CO,  and smoke  levels,  but  no  corrections  could be generalized.  In
 another  study of automotive spark  ignition engines, ambient humidity
 variations  were shown to  affect HC  levels, and temperature and pressure
 changes  to  affect  HC and  CO emissions(32).  However, no factors could be
 generalized for these effects.
       Although the nine  large-bore engine manufacturers provided ambient
 conditions  (barometric pressure and inlet air temperature and humidity) for
 much  of  their  emission data, none of them reported emission data for a given
 engine operated under a systematic variation of ambient conditions.   Thus, at
 this  time it  is not possible to directly derive ambient correction factors
 for  large-bore engines.  Nevertheless, the response of these large-bore
 engines  to  changes in ambient conditions is anticipated to be similar to that
 observed in the smaller bore diesel and gasoline engines for which ambient
 correction  factors have been developed.  In fact,  one large-bore manufacturer
 has  adopted a  humidity correction factor based on smaller bore engines to
 correct  NOx emissions data from diesel and natural gas-fired engines (33).
 Although this manufacturer has not conducted a systematic study of the effect
 of ambient  humidity on NOx emissions,  he believes  the  correction factor  derived
 from  data on smaller bore engines  is reasonable.   This belief is based on the
 reasonable  correlation obtained by using these correction factors for  a  limited
 number of tests with his own engines.
       This section will,  therefore,  illustrate the effect of ambient
 variations  on reported NOX levels, briefly review  existing ambient correction
factors,  and recommend those suitable  for  application  to large  bore  engine
 data.  (A more detailed discussion can be  found in Appendix  C.2.)  These
 ambient correction  factors will  then be used wherever  possible  in the
                                   4-12

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remaining sections of this chapter to correct  the  data reported  by  the  engine
manufacturers.

4.2.1.1  Examples of Ambient Effects on NOX Emissions  from  1C  Engines
       As mentioned above, several studies  have shown  the effect  of  ambient
humidity on NOX emissions(34,35,36).  Figure 4-1(37)  1s taken  from  one  of
these studies and Illustrates the variation 1n specific humidity  each month
during the year 1969 for Dearborn, Michigan.  For  this area,  ambient humidity
varied from 20 to 120 grains H2°/lb dry a1r over tne year-   Tne  e^ect  of
this variation on NOX emissions is shown in Figure 4-2(38,39)  using the
correction factors that have been derived from experimental  work  for gasoline
and dlesel engines.  The NOX levels are shown to deviate as  much  as 25
percent from  levels measured at standard conditions.   Moreover,  the
corrections factors used vary significantly as well,  depending on the
particular study and type of emission source.
       Variations in ambient temperature have  also been shown  to affect NOX
emissions.  This effect is illustrated in Figure 4-3(40,41)  and  ranges  from
5 to 25 percent depending on the particular study.  Although the  effect for
dlesel engines 1s not as large as that produced by ambient  humidity
variations, the change in brake specific emissions (g/hp-hr) can  be
significant.  This is particularly true for some large-bore  spark ignition
engines, which emit as much as 20 g/hp-hr.   For these  sources  a  5-percent
ambient correction means a change in the reported  level of  about  1  g/hp-hr.
       Variations in barometric pressure also can  be  expected  to  affect NOX
emission(42,43).  Only one study, however,  has evaluated this  ambient
variation(44).  This investigation used carbureted gasoline  engines and found
NOX variations of as much as 40 percent due to changes in  ambient pressure.
                                   4-13

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K
Diesel Engines Large-bore
-1.20
- 1.10
1.0
- 0.90
- 0.80

                                                        natural  gas  engine

          Based on range of ±30°F from standard temperature 85°F.   Note:  K > 1  for
          temperatures less than 85°F.

          Reference 40.

          Based on change in NOX emissions with manifold  inlet  temperature.   Assume
          change in ambient is equal to change in manifold temperature.   From
          Reference 41.
 Figure 4-3.  Effect of ambient temperature on NOX emission levels from  1C  engines.'

-------
These changes were attributed largely to variations in A/F ratio in the
carbureted gasoline engines.  However, a correction factor for this effect
could not be derived for the different carbureted engines because each
engine's emissions response to changes in barometric pressure was too
inconsistant to generalize a correction.
       Despite the lack of a quantifiable correction for changes in ambient
pressure, several studies have shown that scatter in emissions data taken at
different ambient humidities and temperatures can be reduced, significantly,
by applying the appropriate correction factors.   For example, Figure 4-4(45)
illustrates the reduction in data scatter that is achieved with emissions
from HD gasoline engines by correcting for humidity only.  The average
standard deviation from the six engines was reduced by a factor of about six
after applying a correction for humidity.
       Figure 4-5(46) illustrates a similar result for ambient temperature
and humidity correction of diesel engines emissions.  The average scatter
after correction was reduced to about one third  of the scatter before
correction.   Note, that in absolute terms,  the reduction in scatter for
diesel engines was smaller (approx.  0.5 g/hp-hr)  compared to the reduction
for gasoline engines (approx.  1.5 g/hp-hr).  Both studies,  nevertheless,
indicate that scatter in emissions data can be reduced significantly by
correcting observed NOX levels to standard conditions.
4.2.1.2  Selection of Existing Ambient Correction Factors for Application to
         Large-Bore 1C Engines
       All  existing ambient  correction factors were reviewed that  potentially
could be applied to adjust data from large-bore  engines.   A detailed
description  of this  review is  presented in  Appendix C.2.   Candidate factors
are presented below.   This discussion is divided  into  two sections  depending
                                   4-17

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I
I—•
CO
               2.0 -
            I
            Q.
            o

            -M
            
-------
     1.0
     0.8

 O)
 IB
     0.6
     0.4
 X   0.2
                  A
                 5.2
Before ambient correction
   B
  7.3
 C
7.6
 D
7.8
 E
9.5
                                                            oo
                                                            i*
                                                            N
                                                            CO
                                                            I
                                             After ambient
                                             correction
                                                                 Engine  number
                                                         13.3   NOX emission,
                                                                g/hp-hr §  75  grains/
                                                                Ib. dry air,  85°F,
                                                                29.92  inches  Hg.
 For Federal  13 mode composite cycle for HD diesel  engines.
DAmbient humidity varied  from 35  to 125  grains/1b dry;  temperature from 70  to  115°F.
      Figure 4-5.   Effect of humidity and  temperature on emissions scatter for six
                   HD diesel  engines** (Reference 46).

-------
 on whether the correction factor can be applied to data from  (1)  spark
 Ignition (SI) or (2) compression ignition  (CI)  engines.   Factors  that have
 been selected to correct both uncontrolled and  controlled emission  data from
 the nine large-bore engine manfacturers are summarized  following  this
 discussion.

 Factors Applicable to SI Engines
        Three ambient humidity correction factors  are  potentially  applicable
 to large bore,  natural  gas fueled  engines,  particularly four-stroke,
 carbureted versions.   These factors  are summarized  in Table 4-1(47,48,49)
 Figure  4-6 is  a  comparison of  the  three factors over  a typical range of ambient
 humidities.   Note  that  only one  of the  three factors  is at a constant load
 factor  (Equation (2b));  the others are  based on composite test cycles for
 vehicles.
        As  Figure 4-6  indicates, there is a considerable difference in
 correction factor  depending on the study.  All of the studies  show,
 nevertheless, that  ambient humidity has a significant effect  on NOx  level-
 The result for Equation  (3),  based on light-duty automotive gasoline vehicle,
 shows the  greatest  sensitivity to variations in  ambient humidity.  These
 varied  responses of NOX  level  to changes in ambient humidity  are not
 unexpected since engines react differently to changes in inlet  conditions.
 Their response generally depends on their A/F ratio, fuel  metering and
 distribution system, and ignition characteristics.  Since large-bore 1C
engines typically operate at  a constant  rated load,  the  constant  load
 correction factor (Equation (2b)) has been  selected for  application  to the
reported data.
                                   4-20

-------
                            TABLE 4-1.  AMBIENT HUMIDITY CORRECTION FACTORS FOR SI ENGINES
no
                       Equation No.
                           (1)
                          (2a)
                          (2b)
                          (3)
              Correction Factor
K = 0.634 + 0.00654(H) - 0.0000222(H)2 Compo-
site Factor (9 Mode Federal HD Gasoline Test
Cycle)

K = 0.796 + 0.175(H/100) + 0.129(H/1002)
Composite Factor (Federal Test Cycle, LD
Gasoline Vehicles)

K = 0.844 + 0.151(H/100) + 0.075(H/100)2
50 mph, Constant Load

K = 1/(1 - 0.0047(H-75)) Composite Factor
(Federal Test Cycle, LD Gasoline Vehicles)
                     H = specific  humidity  in grains H20/lb dry air.
Reference
    47
   48
   48
   49

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       Previous investigators have been  unable to establish  an  ambient
temperature correction factor for spark  ignition 1C  engines  because  various
automotive engines respond quite differently to inlet  air  temperature
variations (see Appendix C.2).  A limited amount of  data exists for  large  1C
engines that show the variation in NOX emissions with  ambient temperature, or
manifold air temperature for turbocharged units.  Figure 4-7(50)  illustrates
the change in NOX level with a change in manifold air  temperature for a  large-
bore, four stroke per cycle, turbocharged (4-TC) gas engine.  This response
indicates approximately a 1-percent change in NOX level per  °F  change in
manifold air temperature.  (A change in  manifold air temperature  is  nearly
equivalent to the same change in ambient temperature.)
       Figure 4-8(51) indicates the response of NOx  emissions with changes in
ambient air temperature for large-bore,  blower-scavenged gas  engines.  These
results show approximately a 2-percent change in NOx Per 0|r  Cnan9e-
Both.Figures 4-7 and 4-8 indicate that NOX emissions from  large-bore engines
are very sensitive to ambient temperature variations.  Therefore  the results
of Figure 4-7 will be applied to all turbocharged gas  engine data, and the
results of Figure 4-8 will be applied to all nonturbocharged  gas  engine  data.
Factors Applicable to 1C Engines
       A survey of the literature established two sources  that  have  reported
ambient correction factors for truck-size diesel engines.  In the study  by
Krause, et. al., a factor was developed  that included  the  effects of
temperature and humidity(52).  The results of this study were subsequently
adopted by the EPA for mobile heavy duty diesel engines.   The other  study  was
conducted by the Coordinating Research Council (CRC) and only investigated
                                   4-23

-------
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                  80          100         120         140

                           Air manifold temperature, °F
                                                                   0»
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                                                                   I
                                                                   <
160
   Figure 4-7.   Effect of manifold air temperature on a  large-bore
                4-TC engine (Reference 50).
                             4-24

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                 40       50       60       70
                              Air temperature, °F
80
90
100
      Figure 4-8.  Test results of NOx emissions versus intake air
                   temperature for two blower-scavenged gas engines
                   (Reference 51).
                               4-25

-------
 the effects of ambient humidity(53).  (A more detailed discussion  of  both
 studies can be found in Appendix C.2.)
       Figure 4-9(54»55)  shows the ambient humi dity correction  factors
 developed from these two studies.  The ambient  humidity factors for SI
 engines are also shown 1n Figure 4-9.  In general,  SI engines  appear  to  be
 more sensitive to ambient humidity variations than  CI engines.   Note  that the
 results from the two CI engine studies are shown for specific CI engine  types
 (e.g., four-stroke turbocharged,  aftercooled engines).   In  general, the  data
 show that NOX emissions from different engine types,  particularly  at  low
 humidity levels,  respond  differently to  changes  in  ambient  humidity.
       The Krause study also investigated the effect  of  anbient  temperature
 on NOX emissions.  Figure 4-lC)(56) presents  the  correction  factors that were
 derived for these smaller bore engines.   It  shows that  NOX  emissions  from
 naturally aspirated and blower-scavenged engines  are more sensitive to inlet
 air temperature changes than are  the  emissions from  aftercooled  units.
       Since the Krause study systematically examined the effect of both
 temperature and humidity  for a number of CI  engine types, his correction
factors have been selected for application to similar large-bore engine
 types.

4.2.1.3  Summary of Ambient Correction Factors for Application to Large-Bore
         Engine Data
       Table 4-2(57»58»59)  summarizes  the  anbient correction factors that
have  been  selected  for  application to the  data reported  by  the nine large-
bore  engine manufacturers.   Note  that, with  the exception of SI temperature
factors,  all  the  corrections  are  based on  studies of  smaller bore automotive
engine  types.   The  corrections for CI  engines are given for specific engine
                                  4-26

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                    Fiaure 4-10.  Correction factors for temperature for CI  engines (Reference 56).

-------
          TABLE 4-2.  EXISTING 1C ENGINE AMBIENT CORRECTION FACTORS FOR APPLICATION TO LARGE-BORE  ENGINES
Fuel
Diesel &
Dual Fuel (CI)
Humidity and
Temperature
Correction
Natural Gas (SI)
Humidity
Temperature
Correction Factor3
K = l/(l+A(H-75) + B (T-85))
H = observed humidity, grains H^O/lb dry air
T = observed inlet, air temperature, °F
Type A
2-BS -0.00242
4-NA -0.00231
4-TC, AC -0.00231
B
0.00235
0.00255
0.0017
/H \ / H \2
v n PAA 4. n i Ki / l-i. o n7£ i i
K - 0.844 i 0.151 ^1()0J« 0.075 \^QQJ
BS K = 1 - (T - S5)(0.017)
TC K = 1 - (T - 35)(0.010)
Comments
Rated load correction for
humidity and temperature
(from Ref. 57).
Rated load correction for
humidity only (from Ref. 58)
Ambient temperature correc-
tion only (from Ref. 59)
r\3
10
           NOV corrected = (K) NO  observed
             A                   A

-------
types.  In addition all the factors are based on rated load conditions,  since
large bore engines typically operate at,  or near,  rated load,
       Although ambient humidity and temperature variations can significantly
affect the NOX emissions that are measured from a  particular engine,  these
variations, in general, are not responsible for the large variations  in
uncontrolled emissions that were reported for similar engine types by
different engine manufacturers.  The other sources of data variability
(largely measurement practices and design differences among models) are
discussed in Sections 4.2.2 and 4.3.

4.2.2    Effect of Measurement Practices
        Previous studies have shown that  sampling  instrumentation and
procedures have a large effect on emission levels.  For example,  a series  of
studies conducted by the Coordinating Research Council (CRC) indicated that
uncertainties in the measurement of NOX levels can range as high  as 40
percent^  '.   This conclusion was based on the standard deviation of
measurements reported by different laboratories for the same emission source,
expressed as a percentage of the mean emission level.  CRC concluded  that  this
uncertainty could be attributed largely to poor calibration and measurement
procedures.  The EPA, then in cooperation with CRC, showed that these un-
certainties could be reduced to less than 5 percent using a specific  set of
procedures(61).   Since then, EPA has proposed that these procedures  be  used
to certify mobile, heavy-duty diesel and  gasoline  engines starting with  the
1979 model year.  The following paragraphs will briefly discuss the
measurement practices of each of the nine large-bore engine manufacturers  who
reported emissions data.  (Additional details regarding these practices  can
be found in Appendix C.3.)  Then uncertainties for each manufacturer's
                                   4-30

-------
 practice  will  be  estimated  relative to the proposed EPA procedure.  These
 uncertainties  will  be  used  in Section 4.3 to establish upper and lower bounds
 for  estimated  average  emission  levels from large-bore 1C engines.
        Table 4-3(62»63»64»65) indicates which of the four measurement
 practices  was  used  by  each  of the manufacturers.  Note that two manu-
 facturers, Alco and Ingersoll-Rand, used what is essentially the EPA
 procedure.  For the  purpose of  this discussion the EPA procedure will serve
 as a reference for  comparison with the other three procedures,  since it is
 believed  to be the  most  accurate.
        Figure  4-11  illustrates  each of the four procedures schematically,
 and  Table  4-4  summarizes the sources of error for the DEMA, SAE, and EMD
 practices.  (A more  detailed discussion of these procedures can be found in
 Appendix C.3.)  The  primary shortcoming of these practices is their failure to
 adequately define instrument performance and sample transfer procedures.
 Unheated sample lines, inappropriate water removal  devices, system leaks, and
 failures of the converter in the chemiluminescent instrument all lead to
 errors  in the  measurement of NOX in the sample gas.   The use of NDIR
 instruments (SAE/EMD practices), can lead to overstated  values  of NOX
 emissions due  to interferences  resulting from the presence of water vapor in
 the  detector cell  of the NDIR instrument.  Considered together,  these sources
 of error can cause  a large  uncertainty in reported  NOX levels.   Figure 4-12
 illustrates the overall uncertainty for data reported by each of the nine
 engine manufacturers.  (Again,   a more detailed discussion of these
 uncertainties   can  be found in Appendix C.3.)    Note  that manufacturers  using
the SAE or EMD procedure could experience uncertainties  of  +20  percent.
Manufacturers  using the DEMA practice,  in contrast,  are  more likely to
experience understated (5 to 15  percent)  NOX  levels  due  to  a loss  of NOX
                                   4-31

-------
  TABLE 4-3.  LARGE-BORE ENGINE MANUFACTURERS MEASUREMENT PRACTICES
                                       Measurement Practice
 Manufacturer                   EPAa     DEMAb     SAEC     EMDd
Alco                             X
Caterpillar                                         X
Colt                                       X
Cooper Energy                              X        X
DeLaval                                    X
ElectroMotive (GMC)                                         X
Ingersoll-Rand                   X
Waukesha                                            X
White Superior                             X
 (Div. Cooper)
aEPA's proposed practice for 1979 Heavy Duty Diesel  and  Gasoline
 Enginesv62).
 Diesel Engine Manufacturers Association (DEMA)  Exhaust  Emission
 Measurement Procedure for Low and Medium Speed  Engines(63).
°Society of Automotive Engineers (SAE)  Recommended Practice J177a^63V
 ElectroMotive Division of General Motors Corporation Practice^65).
                             4-32

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                          TABLE  4-4.  SOURCES OF ERROR FOR DEMA, SAE,  EMD  EMISSION  PRACTICES
                              DEMA (CL)
CO
en
Unheated sampling lines permitted
No specification of sample residence
time in sampling line, or system re-
sponse time
Leak checks are not specified
Water removal device can be located
at analyzer, but before NO?-»-NO
absorption in water trap
Chemical driers permitted
No instrument specifications
Converter efficiency checks not
specified
No calibration procedures specifed
Calibration and span gas specifica-
tions not defined
                                                 EMD (NDIR/NDUV)/SAE (NDIR)
•  Unheated sample lines
•  No sample residence or system
   response time specified
•  Leak checks not specified
•  Allow chemical drier
0  Calibration procedures not specific
   (e.g., what constitutes out-of-
   calioration, how calibration points
   are curve fit, etc.)
0  Calibration and span gas blends and
   dilutents not specified by SAE.
   EMD has "own" specifications.

-------
during the transfer of the sample gas to the relatively interference-free
chemiluminescent analyzer.  These estimates of uncertainty will  be used to
place upper and lower bounds on the average uncontrolled emission levels
computed in Section 4.3.

4.3    UNCONTROLLED EMISSION LEVELS
       This section presents data on uncontrolled emissions from large-bore
engines.  Average uncontrolled NOX emissions from these engines, weighted
according to sales, were  derived from data supplied by manufacturers.  By
applying a specified degree of NOX control to these average uncontrolled
emission levels, potential controlled (regulated) emission levels can be
established.  The degrees of NOX control that can be applied are identified
in Chapter 6,  which summarizes demonstrated alternative controls.
       This approach to setting the standards requires an adequate sample of
emission data for each manufacturer's engine.  Section 4.3.1 discusses the
current data base, and shows that emissions data have been reported for about
80 percent of all the large-bore engine models manufactured to burn diesel,
dual fuel, and natural gas.  This large existing data base is representative
of all the engines to be  affected by standards of performance.
       Section 4.3.2 presents the uncontrolled emissions data for diesel,
dual fuel, and natural gas engines, and examines the sources of  variations in
these data.  Differences  in the ambient conditions (temperature  and humidity)
and procedures for measuring the emissions account for only small variations
in the data.  The largest source of data variations is differences in engine
design.  These differences and their effect on NOx emission levels are
discussed in Section 4.3.3.
                                   4-36

-------
        Because of  these differences, a method  is needed to characterize
 uncontrolled emissions from each of the three  fuels for which standards of
 performance will be proposed.   In Section 4.3.4, representative uncontrolled
 NOX  levels for each fuel are determined by weighting each manufacturer's data
 (corrected for ambients where possible).  Weighting is based on the percen-
 tage of total horsepower sold by each mnaufacturer during the past 5 years,
 and the weighted levels are bounded by estimates of measurement uncertainty,
 based on each manufacturer's procedures.

 4.3.1   Existing Data Base
        The extent  of the current emissions data base is illustrated in Table
 4-5, which shows the number of  large-bore manufacturers who produce engine
 models  within the  diesel, dual fuel, and natural gas categories.  The second
 row of  the table shows the number of models produced for each engine type
 (e.g.,  2-BS, 2-TC, 4-NA, and 4-TC).  The lower two rows show the number of
 models  within each fuel and engine type category that contain (1) uncontrolled
 and (2) controlled emissions data.  Uncontrolled emissions data are available
 from every manufacturer of large-bore engines, although a few manufacturers
 have not conducted tests to reduce NOX emissions from their engines.
        In general, as shown in the last column of Table 4-5,  there are
 uncontrolled emissions data for about 80 percent of the models produced for
 each fuel category.  The current data base contains more data than for those
models  listed in Table 4-5,  since there are  data for several  engines  of the
 same model  for some manufacturers.   This additional data is useful in
determining differences in emissions data  from engines  of the same, and
different manufacturers,  as  discussed in Section 4.3.3.   Thus, a substantial
data base exists  for characterizing uncontrolled emissions from diesel, dual
fuel, and natural  gas engines.
                                     4-37

-------
                                       TABLE 4-5.  EXTENT OF EXISTING DATA BASE
Fuel
Strokes
Air Charging
No. of manufacturers
No. of models9
No. of models with
uncontrolled data
No. of models with
controlled data
Diesel
2
BS
2
2
2
2
TC
2
2
2
2
4
NA
1
3
1
1
TC
5
8
6
5
Dual Fuel
2
TC
1
1
1
1
4
TC
4
5
4
3
Gas
2
BS
2
2
2
2
TC
2
5
6
6
4
NA
4
5
4
3
TC
6
14
10
7


Diesel
6
15
11
10
Overal 1
Dual Fuel
4
6
5
4
Gas
7
28
23
18
CO
00
           A model is a group of engines that  share  the  same  fuel,  air charging,  strokes/cycle,  manufacturer,
           bore, and stroke.

-------
 4.3.2   Uncontrolled Emission Levels
        Uncontrolled emissions of NOX, CO, and HC  (and nonmethane HC where
 measured)  are  shown on Figures 4-13 to 4-15.  On each figure the data is
 plotted separately for each fuel (diesel, dual fuel, and gas), and is
 differentiated  by engine type (i.e., 2-BS, 2-TC, 4-NA, and 4-TC).  Since 1n
 general, the CO  and nonmethane HC  levels from these engines are considerably
 lower than the  limits that apply to mobile vehicles and engines,4/ this
 section is concerned primarily with NOX emissions.  The effects of NOX
 reduction techniques on CO, HC, and smoke emissions are discussed in Section
 4.4.12.  Figures 4-13 through 4-15 show that uncontrolled emission levels
 vary considerably within each category of fuel and engine type.  In Figure
 4-13, fuel consumption, particularly for diesel  and dual-fuel  engines,
 remains relatively constant despite wide variations In NOX levels among all
 engine  types.  Since both NOX emissions and thermal efficiency increase as
 cylinder temperature increases,  efficient engines (low fuel consumption)
 would be expected to show high NOX emission rates.  As shown in Figure  4-16,
 this is not the case among all  engines of one fuel.  NOX levels and four- and
 two-stroke diesel engines shown on Figure 4-16(a), however, appear to
 increase as fuel consumption decreases, but other trends are not apparent for
 other fuels and engine types.   Although other design features  (e.g., manifold
 air temperature, air-to-fuel ratio, speed, torque, etc.) are probably more
4/For example, the proposed Federal  Government  standards  beginning  in  1979
  for heavy-duty gasoline and diesel  engines  are 1.5 g/hp-hr  hydrocarbon
  (HC), 25 g/hp-hr carbon monoxide (CO),  and  10 g/hp-hr  hydrocarbon plus  ox-
  ides of nitrogen (HC + NOX).   California regulations for 1977-1978 heavy
  duty vehicles (greater than 6,000  Ibs)  are  1.0 g/hp-hr  HC,  25 g/hp-hr CO,
  and 7.5 g/hp-hr NOX.
                                     4-39

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-------
Baseline siMmary
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Engine Number
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Stroke Configuration
            Figure 4-14(b).   Uncontrolled  CO  emissions from  dual  fuel engines.

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-------
toettae!
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 lcri Bit*
                o
                      o
                     J3L
                                  Total HC
                                           O
                              O

                              Q
                13 14  711
                            f  7  1C SO Cl  7C
Stnto mflgnvtln
                   t-K
                                  «-TC
           Figure 4-15(b).   Uncontrolled HC engines  from  dual  fuel engines

-------
-pi
oo
Baseline

8
7
S
5

. 4
* 3
2
1
tnglne rater
Stroke
conflagration
Gas:
Uncontrolled data

-
-

.
•
-
0
• o
o
1 71
2-BS







o
o
0
ft
2 69 70
2-TC








0
0 °
0
22 79 39 » 44
4-M
Total HC 0
italMCttMtlt* HC U
o


0

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0
e
0
o
0 0
0 0 0 0 0
D 0 °
42023 282*373140454648495354810?
4-TC
                              Figure 4-15(c).  Uncontrolled HC emissions  from gas engines.

-------
-E*

vo
                      9000
                      8000
                      7000
                      6000
                                                                      I  Q
                                                                       ^
        2-BS     4-NA
Diesel:  O  Q  &  V
            2-TC    4-TC
NOTE:  Darkened symbols
      uncorrected for
      ambients
                                                                                    o
8       10       12       14

    NOX level, g/hp-hr
                                                                                          16
        18
20
22
                  Figure 4-16(a).   Uncontrolled NOx levels  versus  brake specific  fuel  consumption  (BSFC)
                                     for diesel engines.

-------
9UUU
8000
i_
-C
1
0.
-c:
•^
3
•4J
00
1 «->
S fc
O CQ
7000


6000
2-TC 4-TC
Dual fuel ID ^
.


Q
9*
Q ^
• i^
•
•if
V
Q ^
8      10
                                                          14
16       18      20     22
                                        N0x level, g/hp-hr
Figure 4-16(b).  Uncontrolled  NOX levels versus brake specific fuel consumption (BSFC)
                 for  dual  fuel  engines.

-------
01
                     9000
                     8000
                     7000
                     6000
                                                                               m  o
                        2-BS     4-NA

                     Gas: O  O   &   V
                            2-TC       4-TC

                     NOTE:  Darkened syMbols
                           uncorrected for
                           ambients
                                                                  10
12
14
                                                                                          16
18      20
                                         22
                                                               HOX level, g/hp-hr
                   Figure 4-16(c).   Uncontrolled NOX  level versus brake specific fuel  consumption (BSFC)
                                      for gas engines.                                                          '

-------
Important 1n affecting uncontrolled NOX  emissions  and fuel  consumption,
changes 1n operating conditions  intended to  reduce NOX  emissions, generally
causing fuel consumption to increase,  as discussed 1n Section  4.4.
       As noted in Figure 4-13(a),  not  all the  NOX data can  be  corrected for
the effect of ambient temperature and  humidity.   (Ambient  correction factors
for large-bore engines are summarized  in Section  4.2.1.)   The  effects  of
ambient variations, differences  in measurement  practices,  and  Inherent
differences 1n engine design on  the variability of uncontrolled NOX emissions
are summarized 1n Table 4-6(66),   The  data samples include only those  data
from Figure 4-13(a) that could be corrected  for ambient variation.  As  this
table indicates, the largest source of  variations  1n data  1s Inherent
differences In engine design.  This conclusion  is similar  to that of  an
investigation of sources of emission data variability in gasoline
vehicles^67).  In this study, researchers demonstrated  that although
measurement and ambient effects  were significant,  variations among  vehicles
caused most of the variations In NOX emissions  for a series of tests  on similar
vehicles.  Sources of emissions  variability  due to engine design are  discussed
in the following section.
4.3.3  Effect of Engine Variability on NO* Emissions
       The emission data supplied by the manufacturers  vary considerably.  As
discussed above, small variation can be attributed to using different
measurements  techniques or not correcting for ambient conditions.   However,
most of  the differences  in emissions from uncontrolled engines result from:
 (1) variations  in  the production of a particular model, (2) variations among
different models of  the  same  type  (i.e., same strokes/cycle, air charging and
 fuel), or  (3) variations  in  the  number  of cylinders for a given model.  In
                                      4-52

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this section, the uncontrolled data base is evaluated for these sources  of
variability, and furthermore, the data are examined for trends  related to
differences in engine design, such as speed,  torque (bmep),  and manifold air
temperature.  All of these analyses use data  corrected for ambient  variations
by the methods described in Section 4.2.1.

4.3.3.1  Production Variations
       It is difficult to quantify variations in emissions among production
units of the same model.  Up to now,  manufacturers  have concentrated on
obtaining emissions data for different engine models.   Since no emission
regulations (with the exception of smoke limits) have  been 1n effect for
stationary engines, there has been little Impetus for  manufacturers  of large-
bore stationary engines to make exhaust measurements of engines leaving  the
production line.  (In general, fewer  than 100 units are produced each year
for stationary applications by any one manufacturer.)   However, Colt and
GMC/EMD, as well as numerous manufacturers of smaller  bore,  heavy duty
engines for trucks have reported variations in emissions from production
models.
       One large volume manufacturer  of medium-bore engines  has shown that
their laboratory units must emit at levels at least 25 percent  lower than a
performance standard, to insure that  their production  models will  comply with
the standard^**).  jhjs margin accounts for production variables that effect
emission levels in mass produced engines.  For 75 percent of this
manufacturer's current engines meeting the Federal  automotive emission
standard of 16 g/hp-hr (NO  + HC), current variation 1n 1.34 g/hp-hr (N0¥ +
                          A                                             A
HC).  Moreover, this manufacturer believes that the magnitude of production
variation is independent of the emission level, and this belief is  shared by
                                     4-54

-------
several other manufacturers of medium-bore engines(69).  For large-bore
engines, produced individually to higher tolerances, it is anticipated that
this variation should be smaller.
       Colt reported less than a 3-percent difference between production
models in two NOX measurements of one in 1972, the other in 1975,  from a
two-stroke, blower-scavenged diesel  eng1ne(70).  $uch a m&}-\ difference was
unexpected.  They suggest that the variation would more likely be  of
approximately 10 percent for production units, but they have no data to
verify this estimate.  Colt has measured NOX levels of production  spark
ignited engines (2-TC-6) within 3 percent of each other under similar ambient
conditions^1).
       GMC/EMD has reported average NOX levels and standard deviations for
samples of their 2-TC and 2-BS diesel  models(7^).   These results are
summarized in Table 4-7(73).  /\s this  table  suggests,  these variations in NOX
levels of production engines may have  resulted from ambient variations.
Inlet air temperatures varied over a wide range for both the turbocharged and
blower-scavenged units,  and humidity was not recorded.   An attempt  was made
to determine whether these observed  variations in  emissions could  be due to
changing ambient conditions.  First, a correction  was  computed for  each
extreme of the reported  temperature  range, using the methodology presented in
Section 4.2.1.   These two maximum variations were  then  compared to  the
reported data,  to determine if temperature variations  alone could  account for
the scatter.   Next,  a correction was computed for  both  the reported
temperature variations and an assumed humidity variation ranging from 35 to
115 grains O/lb dry air.  These corrections were then compared with the
production variability;  the results are listed 1n Table 4-8.
                                    4-55

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        Based on these corrections,  temperature  variations  alone  could  account
 for all  of the variability in emiss-ions  from  blower-scavenged engines,  but
 not for  turbocharged engines.   If humidity were to  vary over the range  used
 for the  calculations presented In Table  4-8,  then differences 1n ambient'
 temperatures and  humidity could account  for all  the  variability reported for
 these engines.

 4.3.3.2   Model  Variations
       Variations  in levels may be  attributed to differences in models for a
 given manufacturer's  engines.   For  example, NOX  levels for a manufacturer's
 4-TC-6 models may  vary due to  differences in bore, stroke, turbocharger,
 configuration  (inline cylinders  vs.  vee), compression ratio, aftercooler, and
 other  engine design  parameters.  In an effort to identify the magnitude of
 model-to-model  variations, average NOX levels and standard deviations were
 evaluated for different models  of the same fuel  type from each manufacturer.
       Table 4-9 presents the results of this study.  GMC/EMD,  White Alco,
 and Colt  are not included in this table since they each manufacture only one
 engine model (with different numbers of cylinders) per air charging method.
 Seme of these models are configured  for different fuels,  for example, Colt
markets their 38D8-1/8 opposed piston engine model  as a gas,  diesel,  or dual
fuel engine, either blower scavenged or turbocharged.   GMC/EMD  and  White Alco
manufacture one basic dlesel-fueled, turbocharged design  which  differs
primarily in number of cylinders and speed ratings.   GMC/EMD  also markets
blower-scavenged units.
       The other five manufacturers  listed 1n  Table  4-9 produce different
engine models within a given engine  type.  NOV levels  reported  by Cooper for
                                            r\
four 2-TC models varied by an average of  13  percent.   These engines differed

                                     4-58

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 1n bore, speed, number of cylinders, and torque  (bmep), but were  all operated
 at the same  Inlet  and manifold air temperatures.  Del aval's data  Indicated
 only a 4- to 5-percent variation between models for both gas- and diesel-fueled
 engines,  The percent variations shown for Waukesha, Ingersoll-Rand, and White
 Superior, which were uncorrected for ambient conditions, should not be compared
 to the Cooper and Del aval results because differences due to ambient conditions
 could not be factored out.  To the extent that conclusions can be drawn from
 such a small sample size, 1t appears that NOX emissions for any type of engine
 (given strokes/cycle, fuel, and air charging) vary more from manufacturer
 to manufacturer than among models 1n a manufacturer's line.  Emission variations
 due to differences among manufacturers could be related to differences 1n
 speed, bmep, or manifold air temperature.  This possibility 1s addressed 1n
 Section 4.3.3.4.

4.3.3.3  Variations With Number of Cylinders
       Several  manufacturers have suggested that NOX levels will  vary for a
basic engine design depending on the number of cylinders,  since the manifold
 interacts with the turbocharger.  Figure 4-17,  which is a plot of NOX level
 (corrected for ambients)  vs. number of cylinders, shows that NOX levels for
4-TC gas engines decrease significantly as  number of cylinders increase,  but
NOX emissions from 4-TC diesel  and dual-fuel  engines do not indicate a trend
with number of  cylinders.
       Figure 4-18 presents a different interpretation.   The NOX levels
 (corrected for  ambients)  have been  plotted  vs.  the number  of cylinders for
each manufacturer's engines, which tends to reduce other sources of emissions
variation (such as design differences among manufacturers)  that may have been
                                     4-60

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 reflected in Figure 4-17.  Figure 4-18 indicates  that there is no clear trend
 between NOX emissions and number of cylinders for either diesel  or gas  units.
 The effect of changing the number of cylinders causes uncontrolled NOX  levels
 to vary from 3 to 9 percent.   Because EMD data could  not be corrected for
 ambients, this data may not represent the effect  of differences  in the  number
 of cylinders.

 4.3.3.4  Variations in NOX Level  Due to  Other Engine  Variables
        The results  described  above  suggest  that the variations in NOX levels
 reported for engines  of a given  type are probably due  to design  parameters
 that  differentiate  one manufacturer's  engines  from those of  the  others.
 Consequently,  uncontrolled NOX data (corrected for ambients) were plotted vs.
 speed  (rpm),  manifold  air temperature, and  torque  (bmep)  to  reveal  any
 emission trends with these design parameters.
        Figure  4-19  illustrates NOX  level  variation with  speed  for  two engine
 types.   The  data  for gas  engines  indicate increased NOX  emission  with in
 creased speed.  This is in  contradiction to what one would expect from the
 reasoning  that decreased  residence  time  (increased speed) should  result in
 lowered NOX  emissions.  Apparently  other factors  (e.g.,  increased cylinder
 temperature  or inherent design differences among different engines) are
 responsible for this trend.  The 4-TC dual fuel and diesel NOX levels appear
 to decrease somewhat with  increasing speed, as would be expected for lower
exhaust  gas chamber residence times.
       Variations  in NOX level with manifold air temperature are  shown  in
Figure 4-20.  The  4-TC-6 NOX levels  appear to be very  sensitive to the  design
 air manifold temperature,  but the diesel  and dual  fuels NOY levels do not.
                                                          /\
                                     4-63

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These results confirm expectations that NOX  levels from premixed,  vaporized
fuel combustion in SI engines may be strongly influenced by the degree of
aftercooling.  On the other hand, CI engines are characterized by droplet
combustion, and NOX production under these conditions would depend more on
local A/F ratio than on overall air temperature.
       Finally, Figure 4-21 illustrates the wide variation of NOX level with
torque (bmep) for 4-TC-G and 4-TC-D, DF units.  If the cluster of CI data
around 150 psi is ignored, a trend of decreasing brake-specific NOX emissions
with increasing bmep for these units is apparent.  No trend is apparent for
SI  units, except that they are generally not manufactured with bmep's
exceeding 200 psi.
       Based on these preliminary studies, it appears that certain engine
design parameters may explain more of the variation NOX levels for engines of
a given type than variations in ambient humidity or temperature.  That is,
NOX emissions for any type engine  (given strokes/cycle, fuel, and air
charging) vary more from manufacturer to manufacturer than they do among
models within a manufacturer's line.  Differences among manufacturers  are
related to differences  in  speed,  torque (BMEP), manifold air tanperature, and
combustion chamber design.  For example, limited data show that NOX emissions
from 4-TC  diesel  and dual  fuel engines decrease as  speed increases.  NOX
emissions from 4-TC, natural gas  (SI) engines increase  directly as design
manifold air temperature  increases.  However, no clear  trends can be
established for the  effects  of number of cylinders  and  torque  (bmep).  These
observations  suggest that  some form  of weighted average is  required to
characterize  uncontrolled NOX  emissions from  each of the three fuels.  This
approach is  discussed  in  the following sections.
                                      4-66

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4.3.4  Sales-Weighted Uncontrolled Emissions
       Since the sources of variability due to engine design cannot be
specifically identified, a procedure is required to characterize uncontrolled
emission levels of engines which are sold for similar applications.
       The procedure adopted here is to compute a weighted, average uncon-
trolled emission level for engines in the diesel, dual fuel, or natural
gas categories.  The three weighted levels are based on sales of engine
horsepower during the past 5 years for domestic applications.  Sales of
horsepower to standby services were excluded from this computation, since
engines sold for standby applications will be exempted from standards of
performance (see Chapter 9).  Therefore, these engines should not influence
the selection of regulated emission levels.
       The sales-weighted averages for diesel, dual fuel,  and natural gas
engines are presented in Figure 4-22, which also show each manufacturer's
uncontrolled NOX data.  The weighted averages are based on data corrected for
ambient conditions where possible.  The weighted average uncontrolled NOX
level for diesel engines is 11.0 g/hp-hr, for dual fuel units, 8.1 g/hphr, and
for natural gas engines, 15.0 g/hp-hr.  The emission reductions discussed in
Section 4.4 and summarized in Chapter 6 can then be applied to these levels
to determine potential  regulated levels of NOX.
       Measurement uncertainties are associated with each  of  these weighted
levels  and  are shown  in Table 4-10.  These uncertainties should be applied to
the controlled NOX levels that  are  determined by applying  the NOX  reductions
demonstrated by the  alternative  control systems.
                                    4-68

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-------
TABLE 4-10.  WEIGHTED MEASUREMENT
             UNCERTAINTIES FOR SALES
             WEIGHTED NOX LEVELS
Fuel
Diesel
Dual Fuel
Natural Gas
Upper,
g/hp-hr
1.0
1.0
1.3
Lower,
g/hp-hr
0.9
0.4
0.5
           4-72

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4.4    NOX EMISSION REDUCTION TECHNIQUES
        This section describes techniques that have been used, or are being
evaluated for use, to control NOX emissions from 1C engines.  Sections 4.5
and 4.6 discuss control techniques that are designed primarily to reduce
other pollutants  (HC, CO, smoke).  Since SOX emissions are directly related to
the fuel sulfur content, these emissions are discussed in 4.4.13, combustion
of nonstandard fuels.
       The data presented here come from tests on engines whose operating
conditions were altered or which were equipped with emission reduction
devices.  These tests were conducted in manufacturers' laboratories rather
than in field installations.  The discussion of each potential control
technique centers on how the technique works,  its effectiveness, resulting
fuel penalties, effects on other pollutant emissions, technical limitations
to its applications, and cost implications (i.e., additional fuel,
maintenance, or hardware expense incurred by the application of the control).
       Most techniques for controlling emissions from 1C engines involve
engine modifications rather than add-on tail gas treatment facilities.
Engines are designed for optimum operation within one or more of the
following constraints:  application, initial cost, fuel  consumption,
maintenance requirements, reliability,  and commitment of a company's
engineering staff to a design.-'   Each engine design satisfies the constraint
— Stationary reciprocating 1C engines, and particularly the large ones, may
  be required to deliver thousands of hours of continuous operation at rated
  load under varying ambient conditions without significant maintenance, or
  to start without failure by remote control and deliver full power within
  10 seconds.  Since these are severe demands, manufacturers feel committed
  to a proven design and are, therefore, reluctant to make significant design
  changes (e.g., changed piston or cylinder shape or strokes per cycle).
                                   4-73

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differently.   For example,  one engine may operate  at  4e  BTDC  while  another  at
5° BTDC to meet the same NOX emission level.   Therefore,  the  data are  grouped
by engine type and fuel  in  the tables and graphs  that follow.   In addition,
whenever there 1s a specific,  known reason why one type  of  engine responds
differently to the application of controls than does  another,  these
differences are explained in the  accompanying  discussion of the  control
technique.
       The reductions 1n NOX shown here were achieved by investigators for  current
production engines.  In general,  no attempt was made  to  optimize the engine
for the controlled settings (I.e., decrease fuel  consumption,  reduce maintenance,
etc.).  Thus, these results must  be viewed as  those achievable 1f no attempt
1s made to reoptlmize an engine's controlled setting.
       As discussed in Section 4.2.2, the manufacturers'  data were  measured
using one of four measurement practices (EPA,  DEMA, SAE, EMD).  Although
differences in three of these practices relative  to EPA's may cause
uncertainties in the reported levels, the data are considered adequate for
the purpose of setting standards  of performance since these are small  1n
comparison to those in emissions  due to inherent  differences  in  engine
design.   (Measurement uncertainties for uncontrolled emissions are  discussed
in Sections 4.3.2 and 4.3.4.)   Furthermore, the reported emissions  data have
been corrected to standard conditions of humidity and temperature  (when
ambient data were recorded) using the ambient  correction factors presented  1n
Section 4.2.1  Dashed lines on the figures 1n  this section  Indicate NO reduc- ,
                                                                      A
tions after ambient correction.
       The control systems  discussed in this section are listed below  1n
their order of presentation.
       1.  Derating (D)
       2.  Retard (R)
                                   4-74

-------
        3.  Changed air-to-fuel ratio (A/F)
        4.  Turbocharging with aftercooler (TC)
        5.  Reduced manifold air temperature (MAT or M)
        6.  Exhaust gas recirculation (EGR) — internal (IE) and external (EE)
        7.  Water induction (HgO)
        8.  Combustion chamber redesign  (CCR)
        9.  Catalytic converters
       10.  Combinations of the above
 Several  abbreviations will be used on the charts and tables in this chapter;
 they are listed in Table 4-11.  Fuel  consumption data on  the  charts and
 tables  are based on a lower heating value (LHV)  of  18320  Btu/lb (10160
 kcal/kg)  for  No.  2 diesel  oil.
       A qualitative  summary,  by  pollutant,  of  the  effect of  each  control
 technique on  each engine type  as  shown  by the  available data  is  presented  in
 Table 4-12.   Sections  4.4.1  through  4.4.10 give  quantitative  results for each
 of these  techniques.   Graphs  are  presented that  show  (1)  the  NOX reduction for
 the  largest degree  of  control  applied for  each manufacturer and  (2) the effect
 on emissions  and  fuel  consumption  as the  amount  of  control  is  varied.  The
 information presented  in the second set of graphs has  been normalized by the
 baseline  or uncontrolled level.  This condition  is  denoted on the graphs with
 a subscript "U" for uncontrolled.  The controlled condition is denoted with
 a subscript "C" for the controlled level.  Section 4.4.11  summarizes the data
 presented for each of the above control  approaches.
       Then in Section 4.4.12, the effect of NOX control  on the emission of
other pollutants is examined.  This review will help to illustrate whether
standards of performance may be required for  other pollutants  in addition to
                                   4-75

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TABLE 4-11.  ABBREVIATIONS FOR ENGINE TYPE AND EMISSION CONTROL
             TECHNOLOGY
   Abbreviation
              Explanation
      Fuel
        D
       DF
        G
   Strokes/Cycle
        2
        4
   Air Charging
       BS
       NA
       TC
 Control Technology6
        D
        R
       TC
     A or  A/F
     M or  MAT
      EGR(I)
      EGR(E)
        Sb
        INJ
        H20
    W/F or w/f
        PC
        VT
        CCR
        Cat
Diesel
Dual Fuel
Gas (i.e., natural gas)

2-stroke/cycle engine
4-stroke/cycle engine

Blower scavenged
Naturally aspirated
Turbocharged  (and intercooled)

Derating
Retard
Turbocharged  (and intercooled)
Increased air-to-fuel  ratio
Decreased inlet manifold  air  temperature
Exhaust  gas recirculation - internal
Exhaust  gas recirculation - external
Increased speed
Modified injectors
Water induction
Water-to-fuel mass  induction  ratio
Precombustion chamber
Variable throat  precombustion chamber
Combustion  chamber  redesign
 Catalytic converter
 aRM and RMA are used to denote the combined use of retard,
  decreased air temperature, and increased air-to-fuel ratio
 blncreased speed included because data are available, but it is
  not considered to be a viable control technique (Subsection 5.3.12)
                         4-76

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    TABLE 4-12(a).   EFFECTS  OF  CONTROLS  ON  ENGINES LARGER THAN 350 IN3/CYL:  NOX EMISSIONS
Fuel
Strokes/Cycl e
* — ^ir Charging
Control "*" — -^^^
Derate
Retard
A/F
TC
MAT
INJ
EGR(I)
EGR(E)
H20
CR
Diesel
Two
BS
4
4

4
4
4


4

TC

4

—
t
+4

4


Four
NA









4
TC
4
4
4
—
4

t

4
4-
Dual Fuel
Two
BS










TC

4-
4-
—
4-


t


Four
NA










TC
4-
4-
4-
—
4-

t

4-

Natural Gas
Two
BS
4-
4-
4-
4-
4-

4-



TC
4-
4-
4-
—
4-





Four
NA
4
4-
4
t


4-

4-

TC
4
4-
4
—
4



4

t  Denotes emission increase with application of control
4  Denotes emission decrease with application of control
•f-4 Denotes conflicting data with application of control
-  Denotes no change in emissions with application of control
   Blank indicates no data available on effect

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                 TABLE 4-12(b).  EFFECTS OF CONTROLS ON ENGINES LARGER THAN 350 IN3/CYL:  CO EMISSIONS
i
^j
oo
Fuel
Strokes/Cycle
"•"--^Ajr Cha rgi ng
Control •"••^-^^^
Derate
Retard
A/F
TC
MAT
INJ
EGR(I)
EGR(E)
H20
CR
Diesel
Two
BS
4-
4-

4-4
4
4


4

TC

4-


4-
44

4-


Four
NA










TC
4
t
4-4-

44

4-

t4-

Dual Fuel
Two
BS










TC

t
f

4-


4-


Four
NA










TC
f4-
4-
4-

4-4-

4-

4-

Natural Gas
Two
BS
4-
i

4
4-

4-



TC
4-
4-
4-

4-





Four
NA
4-

—
4-


—

4-

TC
4-
4


4-



4-

              4-  Denotes emission increase with  application of control
              4  Denotes emission decrease with  application of control
              4-4 Denotes conflicting data with application  of control
              —  Denotes no change in emissions  with application of control
                 Blank indicates no data available on effect

-------
                TABLE 4-12(c).  EFFECTS OF CONTROLS ON ENGINES LARGER THAN  350  IN3/CYL:   HC EMISSIONS
-p»

ID
Fuel
Strokes/Cycle
"""^---^^Tr Charging
Control -"-^..^^
Derate
Retard
A/F
TC
MAT
INJ
EGR(I)
EGR(E)
H20
CR
Diesel
Two
BS

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4-
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4-


f

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t4-


*4-
4-

—


Four
MA





4-




TC
+
t4-
+4-

H

4-

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Dual Fuel
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BS










TC

t
t

f


4-


Four
NA










TC
t
4-
t

++

t

t

Natural Gas
Two
BS
t
t

4-
+

t



TC
t
t
t

t





Four
NA
t
t






t

TC
t
t
t

t



t

              t   Denotes  emission  increase with application  of control
              4-   Denotes  emission  decrease with application  of control
              +4-  Denotes  conflicting data with application of control
              —   Denotes  no  change in emissions with  application  of control
                 Blank  indicates no data available on effect

-------
NOX.  Finally, Section 4.4.13 discusses the effect of burning nonstandard
fuels on emissions from stationary 1C engines.
       The data that appear in this chapter can also be found in Appendix
C.I, where they are tabulated by engine.  This appendix presents all the
available data on emissions and fuel consumption for large-bore engines.
4.4.1  Derating
       When a manufacturer advertises or sells an engine, he guarantees that
1t will produce a given power at a stated speed.  These conditions are called
"rated conditions" and can be specified either for maximum, intermittent, or
continuous operating conditions.  The maximum rating usually refers to the
peak power that can be achieved by the engine, but manufacturers generally
recommend that the engine not be operated at this level.  Intermittent
ratings typically indicate the power output that the engine can produce for
a 1-hour period with at least a 1-hour period of operation at, or below, the
continuous rating before the next surge to the intermittent level(74).
Continuous rating, of course, applies to uninterrupted operation (e.g., 24
hours per day, 365 days per year with shutdowns for maintenance only).
       An engine can be derated by restricting its operation to a lower level
of power production than normal for the given application.  The effect of
derating is to reduce cylinder pressures and temperatures and thus to lower
NOX formation rates.  Although NOX exhaust concentrations (i.e., moles of NOX
per mole of exhaust) are reduced, it is quite possible for this reduction to
be no greater than the power decrease.  In such a case brake specific
emissions (i.e., grams NOX per horsepower-hour) are not reduced.  This is
especially true for four-stroke turbocharged engines as shown in Figure
4-23(75).  In addition, air to fuel ratios change less with derating for
                                   4-80

-------
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CO
         I
         Q.
c
o
             0
                            40
                               60           80          100

                                   Percent rated torque
                                                                              120
                                                                                             Note:
                                                                                           All engines
                                                                                           from same

                                                                                           manufacturer
                      Figire 4-23.   NOX emissions  versus torque at constant speed (Reference 75).

-------
turbocharged engines than for naturally aspirated or blower-scavenged units.
Thus NOX emissions are less responsive to derating for turbocharged engines.
Derating also reduces the engine's operating temperature,  which then results
in higher CO and HC emissions.  This happens because the temperature
dependent reactions that reduce these pollutants are less  active(7£>).
       Demonstrated NOX emission reduction levels due to derating are shown
in Figure 4-24 for a number of different engine types and  fuel.  Based on
these data,  emission reductions ranged from 1.2 to 23.0 g/hp-hr for naturally
aspirated or blower-scavenged engines and from 0.2 to 10.8 g/hp-hr for
turbocharged units.  Since these results were obtained with varying amounts
of derating, it is more informative to compare the effectiveness of this
emission control technique on a normalized basis -- i.e.,  percent NOX
reduction per percent derate.  On this basis, results for  naturally aspirated
or blower-scavenged engines varied from 0.25 to 6.2, whereas those for
turbocharged units varied from 0.01 to 2.6.  No relationship was found
between normalized effectiveness and uncontrolled emission level, number of
strokes per cycle, or fuel.
       Figure 4-25 illustrates the effect of different amounts of derating on
NOX emissions and fuel consumption for diesel, dual fuel,  and gas engines,
respectively.  Figure 4-25(a) shows that derating decreases brake specific
NOX emission from some diesel engines, but increases them  from others.  In
general, NOX reductions range from 2 to 25 percent for 25 percent derating
and brake specific fuel consumption increases range from 2 to 5 percent.
With 50-percent derating, NOX reductions range from 15 to  45 percent and fuel
penalties from 4 to 16 percent.  Engines No. 10 and 11, both two-stroke
blower-scavenged, achieved the largest NOX reduction (and  highest fuel penalties),
                                   4-82

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Figure 4-25(b).   Effect of different amounts of derate on
                  NOx  emissions and fuel consumption  on dual
                  fuel  engines.
                      4-85

-------
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 Figure  4-25(c).   Effect of different amounts  of derate  on
                    NOX emissions  and fuel  consumption  for
                    gas engines.
                       4-86

-------
        Figure 4-25(b)  also  shows mixed  results for  derating  dual-fuel  engines
 but  with substantially less  variation than  among the  dlesels.  Thus  derating
 caused an Increase  in  NOX in only  one engine.  In general, 25 percent  derating
 reduces NOX emissions  20 to  35  percent  and  increases  fuel  consumption  2 to
 8 percent.   Derating by 50 percent  produces NOX reductions of 30 to  65 percent,
 but  at the  same  time fuelusage goes up 10  to 30 percent.  In general, small
 amounts (25 percent or less)  of derating appear effective  in reducing NOX
 emissions from dual fuel units, and such reductions are accompanied  by fuel
 penalties of less than  8 percent.
        Figure 4-25(c)  shows  that the derating of gas  engines produces a wide
 range  of  NOX reductions.  In  general, the nonturbocharged engines achieve
 the  largest  reductions, since derating  has a greater  effect on their air-to-
 fuel ratio.  For example, blowers on blower-scavenged units operate  at
 constant  speed, independent  of load; therefore, as the fuel flow is reduced
 to decrease  output, the air-to-fuel ratio increases,  causing a NOX reduction.
 The  turbocharged engines, in  contrast,  maintain a more nearly constant air-
 to-fuel  ratio, and consequently, experience less of a NOX reduction.
        Derating does not require additional engine equipment, and the only
 operational  adjustment is to the throttle or governor setting in order to
 restrict  the engine power output.   In most cases,  this adjustment can be made
 in the field, although  one could presumably equip a new engine with a fuel
 pump or carburetor whose maximum fuel  delivery capacity corresponds  to a
derated condition.   When derated,  the  engine's efficiency is  reduced, and
 hence,  the fuel  consumption  is increased.  Moreover, when  an  engine  is
derated,  a bigger,  more expensive  unit must be purchased to satisfy a given
power requirement.
                                   4-87

-------
 4.4.2  Retarded  Ignition Timing
        As mentioned in Chapter 3, combustion is initiated by the injection
 of  fuel oil  in a diesel or dual-fuel engine, or by a spark in a natural gas
 unit.  The effect of variations in the timing of this injection or spark
 discharge is the  same for both kinds of engines; that is the event can be
 described as combustion ignition in both cases.  Therefore, this control
 technique is termed retarded ignition timing, or retard.
       Ignition  in a normally adjusted engine is set to occur shortly before
 the piston reaches its uppermost position (top dead center, or TDC).   At TDC
 the air or air-fuel mixture is compressed to the maximum.  The timing of the
 start of injection or of the spark is given in terms of the number of degrees
 that the crankshaft must still rotate between this event and the arrival of
 the piston at TDC.  The extent of retard is then expressed in degrees
 relative to normal ignition.  Typical retard values are 2° to 6°,  depending
 on the engine.   Beyond these levels fuel  consumption increases rapidly, power
 drops, misfiring  (erratic ignition) occurs,  and smoke from diesel  engines
 becomes excessive(77).
       After ignition,  the burning combustion gases expand, driving the piston
 downward.   This is called the power stroke.   When ignition is retarded, the
 duration of the combustion process does  not  change significantly,  but rather
 is initiated closer to TDC and is extended longer into the power stroke.
Consequently, the combustion process  occurs  later during higher  exhaust
 temperatures.
       In  theory the fuel  delivery system in diesel engines could  be  altered
 to reduce  the duration  of  injection and  thereby decrease the  quantity of fuel
that is combusted late  in  the power stroke.   Such  changes  would  require
increases  in the  injection pressures  above current  levels,  which are  already
                                   4-£

-------
 high.   One manufacturer of medium-bore engines,  Cummins  Engine Co.,  developed
 their  own high pressure fuel  pump for this  application  because there was  no
 suitable commercial  component on the  market.   Low-volume manufacturers  of
 medium-bore engines,  however, depend  on outside  sources  for  their  fuel  pumps
 and have stated that  the inavailability of  this  critical component restricts
 their  use of retard  (e.g.,  to 2° to 6°)  at  this  time(78).  One manufacturer
 of  large^bore engines  reported an  unsuccessful attempt  at  increasing
 injection pressures^79).  He  found that  this  higher  pressure compressed the
 puel and expanded  the  fuel  lines  and  consequently, the fuel  injection time
 was  not  decreased.  Presumably,  the test  could be conducted  with fuel
 handling equipment so  that  expansion  of  the fuel lines,  at least, would not
 prevent  a manufacturer from reducing  his  injection period.
       Retarding Ignition  decreases NOX formation at the expense of  reduced
 efficiency,  thus Increasing fuel consumption.  Emissions of HC  and CO are
 generally insensitive  to retard except in the extreme case where misfiring
 can occur.   That is, the higher exhaust temperatures, which tend to  improve
 the oxidation  of any remaining unburned fuel or carbon monoxide, offset the
 effect of  shorter residence times  in the cylinder.   Smoke in dlesel engines,
 however,  increases rapidly after moderate degrees of retard  (2° to 6°).
       Figure 4-26 presents the level  of reduction  demonstrated for a range
 of engine types.  Based on these data, the percent  of NOX reduction per
 degree of retard ranged from  1.2 to 6.9 for  naturally aspirated or  blower-
scavenged engines and from 0.6 to 8.5  for turbocharged engines.  Actual
reductions due to retardation  between  3 to 10 degrees ranged from 0.4 to 7.3
g/hp-hr for all engines.  The  effect  of the  control  is to consistently reduce
the level of NOX produced,  although the magnitude of  the reduction  can  vary
considerably between  engine types or within  an engine category.
                                   4-89

-------
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Brake specific 8000
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-------
        Several  manufacturers  have  investigated the effect of different
 amounts  of  retard  on  NOX  emissions  and fuel consumption for diesel, dual
 fuel,  and  gas  engines.  Their results are shown in Figures 4-27 and 4-28.
 Figure 4-26 shows  that the effect  of retarding fuel injection on NOX levels
 and fuel consumption  is similar for different diesel engine types.  That is,
 4  degrees  of retard reduces NOX from 22 to 30 percent  (i.e., 26 +4 percent),
 and 8 degrees  reduces NOX 39  to 44 percent.  Note that the NOX reduction per
 degree of  retard decreases for increasing levels of retard.  In contrast,
 fuel penalties  increase at a  greater rate with increasing retard.   Thus,
 4  degrees  of retard causes a  2-percent fuel penalty, 8 degrees a 6 percent
 penalty, and 12 degrees a 12-percent penalty.   Therefore, maintenance and
 durability  considerations aside, there are diminishing benefits to
 retarding diesels  beyond a certain point, because increases in fuel
 consumption exceed decreases  in NOX levels.
       Figure 4-28 shows similar results for gas and dual-fuel  engines,
 although the data  are more scattered.  In general,  ignition retard for  gas
 engines is  not as  effective in reducing NOX levels as it is for diesel  and
 dual fuel engines.  For example, 4 degrees of  ignition retard  gives about a
 15 percent NOX reduction in gas engines  as compared to around  25 percent for
 diesel  and dual fuel  units.   Note that the amount  of NOX reduction remains
 constant after a certain point for the two naturally aspirated engines,  but
fuel consumption continues to increase rapidly.   In addition,  there are
 practical limits of ignition retard for  all  gas  engines.   Spark-ignited
 engines are more sensitive to ignition timing  and,  therefore,  misfire and
exhibit poor transient performance when  the  ignition  timing  is  not  very  close
to the  design point.
                                   4-91

-------
   1.20
   1.10
   1.00
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                                 8      10
                               Retard, •
12      14      16
   1.0
   0.8
 *  0.6
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                  | Same engine model
                                                            16
Figure  4-27.   Effect of different amounts of retard on  NOX
                emissions and fuel  consumption for diesel  enqines
                        4-92

-------
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                                                 44
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Figure  4-28.
Effect  of different amounts of  retard on
NOX emissions  and fuel  consumption for gas
and dual  fuel  engines.
                       4-93

-------
       Special  equipment  is not  required  for  injection  ignition  retard  as
it involves only an adjustment  of  the  engine  spark  or injection  pump  timing.
Typically, the  nominal  setting  of  the  ignition  time is  fixed  by  means of  hardware
items, such as  crankshafts.  Means are then provided for  adjustments, or  fine
tuning, about this nominal  value to compensate  for  variations  in altitude,
fuel, engine wear, etc.  Manufacturers usually  perform  this fine tuning service
during the production run-in of the engine, but the adjustments  also  can  be
made by the operator.  This typically occurs  every  10,000 hours  in  the  course
of normal maintenance,  but  the  setting is actually  verified or corrected  weekly.
       As stated earlier, peak  cylinder temperatures and  pressures  are
lowered by retard, and, hence,  the thermal  and  structural loadings  are
lowered.  However, the  delayed  combustion causes higher exhaust  temperatures,
which may lead to rapid deterioration of the  exhaust valves  if the  exhaust
temperatures exceed the design  limits of the  valve  material.   According to a
manufacturer of gas-fueled  engines, the values  in their current  production
engines can withstand temperatures up to 1300°F, and the  turbochargers  are
limited to 1200°F (these two temperature limits are not inconsistent  because
the exhaust gas cools between the  cylinder exhaust  and  the turbocharger
inlet)(80).  Current cylinder exhaust temperatures  range  from 900°F to
1250°F.  Nevertheless,  one manufacturer determined  that 4° retard of  ignition
in a  dual-fuel engine caused a 25-percent reduction in  the maintenance  life
of his current valve material(81).  Another manufacturer  reported that  his
naturally aspirated SI engines  are presently operating  near their exhaust
material  limits (1300°F) at rated load conditions.   Data from one engine
showed that 10 degrees of  ignition retard caused the exhaust temperature  to
increase from 1263° to 1370°F.   (NOX  emissions  were reduced 17 percent.)
Therefore, the application of retard  to meet  standards  of performance may
                                   4-94

-------
 require  more  frequent  engine maintenance or greater Initial cost for higher
 temperature exhaust material.

 4.4.3  A1r-to-Fuel Ratio Changes
       The air-to-fuel ratio is defined as the mass flowrate of air Ingested
 by  the engine divided  by the mass flowrate of fuel consumed.  This ratio 1s
 termed sto1ch1onetric  1f precisely enough oxygen 1s present in the mixture to
 completely oxidize the fuel.  When the ratio is greater than stoichlometric,
 excess air (oxygen) 1s present, and the mixture is referred to as lean.
 Conversely, a lower than sto1ch1ometr1c ratio 1s commonly called fuel  rich,
 or  simply rich, because more fuel 1s present 1n the mixture than can be
 completely burned.
       The maximum NOX and minimum HC and CO emissions will generally occur
 at  an air-to-fuel ratio slightly leaner than stoichlometric.  Although
 maximum  flame temperatures occur at less than stoichlometric ratios,  maximum
 NOX levels do not occur until lean A/F ratios when oxygen availability is
 Increased.  Perfect mixing of the air and the fuel  never occurs in existing
 engines;  therefore, some excess air 1s necessary for complete combustion and
 minimum HC and CO emissions.  These relationships are shown 1n Figure
 4-29(82)  for  a gasoline-fueled automobile engine.   Similar  curves  apply  to
 dlesel-  and gas-fired units, with different  peak levels for the various  curves
 and shifts in the air-to-fuel ratio that correspond to peak NOX generation.
When the engine 1s operated rich,  HC emissions  rise sharply because the
 available oxygen is no longer sufficient for complete combustion of the  fuel.
The lack  of oxygen for combustion  also means 1t is  not present for NOX
 formation and so,  despite the high  cylinder  teiiperatures, NOX  formation  will
 drop sharply at increasingly rich  mixtures.
                                   4-95

-------
                                                Relative emission levels
   
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       If the ratio is varied in the lean direction, the oxygen availability
will increase but so will the capability of the air and products of
combustion mixture to absorb heat.  Consequently, the peak temperature will
fall, resulting in lower NOX formation rates.  HC emissions will rise with
leaner mixtures due to the lower temperatures which result in increased
quenching along the cylinder walls.  However, since this effect will be
counterbalanced, in part, by the leaner mixtures which occupy the quench
layer, the HC rise rate will not be as sharp as it is with increasingly rich
mixtures.
       CO emissions, which are primarily a function of oxygen availability
and only secondarily of temperature, show a pronounced rise as the mixture
becomes richer than stoichiometric, but little variation as it becomes
leaner.
       To understand the potential effect of air-to-fuel ratio adjustments on
emissions from a particular engine type, one must first examine the ratios at
which the engines normally operate.  The most important engine characteristic
that determines these ratios is the air and fuel charging system.
       In injection type engines,  which include all  diesel  and many dual fuel
and gas varieties,  the air-to-fuel ratio for each cylinder can be adjusted by
controlling the quantity of fuel that enters each cylinder.  Therefore, these
engines can be operated in the lean region where combustion is most efficient
and fuel  consumption is optimum.  On the other hand, carbureted engines are
beset by large variations in cylinder to cylinder air-to-fuel ratios(83).   Of
necessity they must operate near the stoichiometric ratio to insure that no
individual cylinder receives a charge which is too lean to ignite (i.e.,
exceeds the lean misfire limit).  Furthermore, A/F ratios cannot be increased
                                   4-97

-------
too far 1n turbocharged, spark-Ignited engines 1f severe misfiring and
detonation are to be avoided.
       The most practical use of air-to-fuel ratio adjustment as a control
technique 1s to change the setting toward leaner operation,  since
Increasingly rich mixture operation causes substantial  penalties 1n both HC
emissions and fuel consumption.  This technique can be Implemented best on
Injection type engines.  Carbureted engines will require better control of
the air-to-fuel ratio between cylinders before they can operate at leaner A/F
ratios.  In fact, some current carbureted engines, when adjusted to leaner
than normal  air-to-fuel ratios (but still rich), tend to Increase their NOX
emissions because they are moving towards the peak of the NOX versus air-to-
fuel ratio curve.  They are not able to go beyond that  point to the lean
region without mlsf1r1ng(84).
       The emission levels that can be achieved by air-to-fuel  ratio
variation are shown 1n Figure 4-30.  Based on these data, the percent
reduction 1n NOX emissions per percent of Increase 1n air-to-fuel  ratio was
0.12 for the one blower-scavenged gas engine, 1.4 to 6.2 for two naturally
aspirated units, and 1.4 to 7.1 for the turbocharged gas and dual-fuel  units.
Actual reductions in gas engines were about 4 to 6 g/hp-hr for  all but  the
blower-scavenged units and 2 to 3 g/hp-hr for the dual  fuel  units.  The two
dlesel engines displayed smaller decreases in NOX emissions, 0.7 to 0.9, with
the leaner combustion.
       Figure 4-31 shows the effect of changes 1n air-to-fuel ratio (A/F) on
NOX emissions and fuel consumption for dlesel, gas,  and dual-fuel  engines.  In
general, small changes 1n A/F (approximately 10 percent) cause  a large  NOX
reduction (approximately 30 percent) with less than a 5-percent fuel penalty.
This 1s particularly true for natural gas and dual fuel engines which operate
                                   4-98

-------
I
to
10
A/F
9000
Brake specific 8000
fuel consumption
(Btu/hp-hr) 7000
6000
22
20
18
16
NOX level 11
(g/hp-hr)
12
10
8
6
4
2
Normalized reduction3
A/F ratio, old/new
Uncontrolled fuel consumption
Percent increase
Air charging
Strokes/cycle
Engine number
Fuel
Gas
.
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A A
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62.5/68.2 54.7/59.0 — — 32.0/33.4 17.6/16.5 21.5/17.0 32.5/34.7 16/14.1
7127 6775 6780 6660 6942 8180 7840 6374 7590
1-3 1.4 0.6 2.1 5.2 5.6 4.1 2.3 13.9
US TC TC TC TC M M TC TC
2 2 2 2 244 4 4
1 2 66 67* 69 21 44 4 29
aPercent NOX reduction/percent change In A/F.
bDerate 7X
Dual

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1.38 3.9 — 2.40
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224 4
13 78 6 16

Diesel

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0.94 0.73
43.7/40.0 28.6/21 .1
6632 6870
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TC TC .
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77 60

                           Figure  4-30.   Effect  of A/F on  NOX emissions and fuel consumption.

-------
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                                                     DF -  Dual Fuel
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                 70       80        90       1-0      1.10      1.20


                              (A/F)C/(A/F)U
      Figure 4-31.   Effect  of A/F  changes on NOx emissions
                      and fuel  consumption.
                            4-100

-------
 near  sto1ch1ometric (ie.,  peak NOX formation).  Note that  engine numbers  29
 and  60 are  carbureted  and, therefore,  are designed to run  on the rich side of
 the  peak  on the  NOX vs. A/F  ratio curve.  Hence,  they must decrease their A/F
 ratio  (i.e., move  to a richer setting) to achieve NOX reductions.  As Figure
 4-31  shows,  decreased  A/F  causes rapid increases  in fuel consumption.
 Increasing  the A/F,  on the other hand, achieves significant NOX reductions
 with more moderate increases in fuel consumption.  Note that all of the
 engines that increased A/F were turbocharged units which already operate at
 lean  (greater than  stoichiometric) air-to-fuel ratios.  Of course, the
 maximum increase in A/F is limited by the onset of misfiring, as well as
 marginal  transient  performance and poor fuel consumption.
       In practice,  leaner air-to-fuel ratios are obtained by either reducing
 the fuel  input (essentially derating) or by increasing the air input.
 Increased airflow  is accomplished by installing a turbocharger or replacing
 an existing turbocharger with one that is designed to deliver more air.   For
 blower-scavenged units larger blowers can be installed,  or the existing
 blower can  be operated at higher speeds.   These changes, however,  tend to be
 offset by increased parasitic horsepower as  well  as  higher discharge air
 temperatures.
       The mass  flowrate of air into a cylinder (whose maximum volume is
 fixed) can also  be increased by raising the  density of the incoming air
 through cooling.   Intercoolers  are frequently placed  between  the turbocharger
 exit and the inlet manifold to  partially offset the  temperature rise of  the
 air which occurs  as it  passes through the compressor.   (Intercoolers  are
required on large,  turbocharged SI*.engines  to prevent  preignition.)  Both
turbocharging and intercooling  have  other effects  on  emissions  and  will  be
discussed in Sections 4.4.4 and 4.4.5 respectively.
                                   4-101

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        In the case of carbureted engines, increased air flowrates can be
obtained by a change in the shape of the venturi and fuel nozzles in the
carburetor(85).  However, since current carburetor and intake manifold
systems do not distribute a uniform fuel-air mixture to all  cylinders,
significant changes toward lean combustion may require the adoption of fuel
injection in place of carburetW86).  In addition,  increases in A/F ratio
beyond a certain amount reduce the engine's maximum load capability and some
derating is required.

4.4.4  Turbocharging
       The exhaust gas stream from an 1C engine contains energy that is
normally lost when this stream is discharged into the atmosphere.   Some of
this energy can be regained by passing the exhaust through a turbine,  which
is mechanically coupled to a compressor and uses the  energy extracted from
the exhaust to increase the pressure of the incoming  air.  This arrangement,
called turbocharging, is pictured schematically in Figure 4-32(87).
Turbocharging was originally introduced to overcome problems associated with
engine operation at high altitudes where the atmosphere is rarefied.   Since
it increases the pressure of the Incoming air,  a larger mass of air  can be
Injected into the cylinder of a turbocharged engine than of  a blower-
scavenged or naturally aspirated one.   Hence, more fuel  can  be Injected into
the cylinder (the air-to-fuel  ratio for optimum combustion is relatively
intensitive to pressure), thereby allowing an engine  of  given size  and weight
to produce  more power.   Although turbochargers  are normally  designed to
increase an  engine's  output to approximately 1.5 times  its original  power,
they can be  used to raise the  engine's capacity to 2  to 3 times its  naturally
aspirated value,  provided the  basic structure is sufficiently strong.
                                   4-102

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Manufacturers frequently use turbochargers to make engines available that are
intermediate in power between existing nonturbocharged units(88).  This
procedure is more common among manufacturers of medium-bore engines than
large-bore units, since most of the larger engines are already turbocharged.
Two manufacturers of the medium-bore engines have expressed concern that
emission standards which implicitly require the addition  of turbochargers to
all engines  will reduce the  number of engine sizes available  for  purchase
because users will no  longer have the option of buying  engines whose  power
rating falls between the rating  of adjacent  turbocharged  models(89).   Such  a
change could indirectly  increase the  cost to a user  by  forcing him to buy a
higher horsepower  engine than he would  have  purchased otherwise.
        In  addition  to  increasing the  air flowrate,  turbocharging also
 increases  the  inlet  air  temperature  due to the temperature rise  associated
with  compression.   This  increase, however, is  generally offset by the
 addition of an intercooler, or heat  exchanger placed between the compressor
 and the  inlet  manifold (see next subsection for more details).  As seen in
 Figure 4-33, three of the four sets of engines for which comparative data on
 turbocharged and nonturbocharged are available did not show  a rise in the
 inlet manifold air temperature  as a result of the turbocharger.   From the
 standpoint  of emissions, and  in particular NOX formation, two combustion
 parameters  may change when  a  turbocharger is  added:  temperature and  air-to-
 fuel ratio.   If the inlet  air temperature rises, the peak cylinder
 temperature will be correspondingly  higher; hence NOX  formation  will
 increase.   Conversely,  if  the temperature is  reduced,  NOX formation  will  be
 lower.  Changes  in  the  air-to-fuel ratio will also  change NOX emissions,
 depending  on  the  location  of the air-to-fuel  ratio  of  the nonturbocharged
 unit relative to  the  peak  in Figure  4-29 and  the direction  of the change.   In
                                     4-104

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addition,  as the power  output  is  increased,  the  brake  specific emissions will
decrease.   The net result,  as  can be  seen  in Figure 4-33,  is  a NOX reduction
ranging from 3.3 to 34.5 percent  1n the  two-stroke engines for which data  are
available.  The largest reduction 1s  obtained  on the  unit  that runs  at  a
lower Inlet air temperature with  the  turbocharger than 1t  does when  blower
scavenged.  The four-stroke set,  engines 22/23,  operates  very near to
sto1ch1ometr1c, where leaning  the air-to-fuel  ratio  can Increase  NOX
formation.  More Importantly,  1t  was  tested at a higher Inlet air temperature
with the turbocharger than without.
       Since the combustion reactions for both CO and HC go  to  completion
more readily at higher cylinder temperatures and 1n  the presence  of  leaner
air-to-fuel ratios, their emissions are reduced by turbocharging(9°).
Similarly,  smoke emissions will  also be reduced under these  lean  mixture
conditions^1).
       The  addition of turbocharging requires the installation of the
turbocoropressor discussed earlier  and, depending on  the strength of  the
originally  installed parts, may  require the replacement of a number  of other
engine  components  (piston rings,  connecting rods, wrist pins and cylinder
heads) with higher strength parts.  This may  be necessary because
turbocharged  engines operate  with  higher cylinder temperatures and pressures
and  thus  experience  higher thermal and  structural loads.
        turbocharging is  generally offered  as  an option to most current
naturally aspirated  or blower-scavenged engines  and,  as such, 1s well
demonstrated and  readily available.  As  an  emission  control   technique  it  1s
most effective if used in conjunction with  some means  of  cooling and
 compressed air,  such as  the heat exchanger  (intercooler)  discussed  in  the
next section.
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       The addition of the turbocharger  (either  with  or without  an
intercooler) Introduces an operational  problem only 1f the  engine must
respond to rapidly varying loads  and speeds.  Stationary  engines used 1n
portable air compressors could face such demands,  but 1t  1s  unlikely that the
large engines for which standards are now being  developed would  experience  a
problem.  The problem 1s one of smoke generation due  to rich  combustion and
arises during acceleration because the  fuel  flowrate  increases much more
rapidly than the air flowrate.  The air flowrate depends  upon the power
delivered to the turbocompressor, which  depends, in turn, on  the power that
the turbine can extract from the  exhaust gases.   The  energy carried by these
gases increases only when the engine output  increases.  Hence there is a
built-in lag in the system which  results 1n  insufficient  air  for a short time
after the fuel flowrate 1s increased.  Some  manufacturers have solved this
problem by careful control of the fuel  rate  or by using some  of  the
compressed air from the storage tank (if the engine is used to drive an air
compressor)(92).  Another attempt at a solution  1s being  tried by one
manufacturer of turbochargers, who is currently  developing  a  turbine with two
kinds of blades.  Some of these extract  energy efficiently  at low pressures
and flowrates while others funtion best at the higher flow  conditions
corresponding to rated engine operation^).
       Therefore, turbochargers should be considered  applicable  to  all large
engines, either because the application  does not involve  rapid load
fluctuations or because of compensatory designs.
4.4.5  Reduced Manifold Air Temperature
       The installation of a heat exchanger  (commonly referred to as an
intercooler or after cooler) between the  turbocharger  and  the  intake manifold
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(see Figure 4-32)  normally accompanies  the  use  of  turbocharging  in  engines
over 500 hp.  The function of  the intercooler is to  lower the temperature of
the intake air after it has been heated by  turbocharging  (see Section  5.3.5).
Decreasing the temperature increases  the density,  thereby allowing  more  air
to enter the cylinder.   This in turn  permits  higher  fuel flowrates  and
consequently higher power output.  Decreasing the  inlet temperatures also has
the secondary effect of reducing the  peak combustion temperature and,  hence,
the NOX emissions.
       Decreasing manifold air temperature will result in an  increase  in HC
and CO emissions because their respective reduction  reactions  now proceed at
a slower rate.  However, some diesel  engines  display a contradictory trend
for CO.  Presumably the temperature is  still  high  enough to allow the
reaction to proceed to completion, and  the increase  in power,  then, results
in a decrease in brake specific emissions.
       An  intercooler is either provided with,  or  available as  an option on,
most current turbocharged engine models.  In fact, an intercooler must be
used when  a carbureted,  natural gas engine is turbocharged  to prevent  the  hot
air from  detonating the  air-fuel mixture prior to its entry into the
cylinder(9*).  Additional hardware requirements include the heat exchanger,
a  circulation device for the  cooling medium  (either  a fan for cooling  air,  an
enlarged  water pump for  engine  coolant  water, or  a new source of cooling),
and a  control mechanism  to regulate the  degree of cooling.
        It is  also  possible to use increased  cooling as an emission control  in
engines that  are  already turbocharged  and intercooled.  Depending on the
level  of  cooling  necessary and  the availability of  a suitable low temperature
heat  sink,  this  can  amount to installation of  a larger heat exchanger or the
addition  of  an  entire  heat  exchanger system  using air, well or municipal
                                    4-108

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 water,  or a cooling tower.   Self-contained radiators,  similar to those found
 on automobiles,  are the most commonly  used cooling system for large engines.
 Large radiators  could deliver air  to the  Inlet manifold that 1s no more than
 15°F hotter than the ambient air.  Thus,  1n a hot area where daytime air
 temperatures frequently reach 100°F, the  Inlet manifold air temperature could
 not be  reduced  below about  115°F.  Cooling towers would have to be used 1n
 such a  location  to  reach lower  Inlet air  temperatures unless a large supply
 of cold water were  available for once-through cooling.  Under typical
 conditions  for  a hot and humid  location,  the turbocharged Inlet air
 temperature of 130°F could  be cooled to nearly 100°F with a cooling tower.&
        The  data  1n  Figure 4-34  are all for an Intercooler exit temperature of
 100°F.   The normalized  NOX  reduction (percent NOX reduction per degree
 Fahrenheit  temperature  reduction) was used to Interpolate or extrapolate the
 available data,  where necessary, to the 100°F temperature for ease of
 comparison.   This normalized  NOX reduction value ranged from 0.9  to 1.2 for
 gas  engines,  0.6 to  2,2 for dual-fuel  units,  and from 0.1  to 0.3  for  dlesel
 engines.  In  general, manifold  cooling was most effective  on gas  engines,
 particularly  two-stroke models.  This 1s probably due to the large  quantities
 of  scavenging air used by these units.   When  this air 1s cooled,  1t not  only
 reduces  peak  combustion temperatures  directly but also Indirectly  by cooling
 the  cylinder walls.
       Figure 4-35 shows the effect of  lowering  the manifold air temperature
 on NOX emissions and fuel consumption.   The results  vary and depend on the
-'Based on 100°F ambient air temperature,  90-percent  humidity with a
  resultant minimum Intercooler water temperature  of  97°F, and typical heat
  exchanger effectiveness.
                                   4-109

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engine type.  In general,  reduction of 10 to 40 percent  can  be  achieved with
a 25-percent decrease in the baseline manifold air temperature.   If  one
assumes a baseline temperature of 130°F (a common aftercooler  design exhaust
temperature), then a 25-percent reduction brings the manifold  temperature  to
100°F.  As noted above, many engines operate in hot climates (e.g.,  gas
pipeline compressor units  and electric generating systems  in midwestern
utilities).  Such engines  would require large quantities of  cold water or
refrigeration (which consumes so much energy that derating may  be equally
effective) to reduce the inlet manifold air temperature  further.

4.4.6  Exhaust Gas Recirculation
       Exhaust gas recirculation (EGR) systems function  by replacing some  of
the incoming excess air with exhaust gases.  The purpose of  this is  to reduce
peak temperature by providing a mass which can absorb some of  the heat
released during combustion.  The value of using exhaust  gas  is  that  it serves
as a heat  absorber without making available as much additional  oxygen to the
nitrogen atoms as turbocharging or operating with a high air-to-fuel ratio
would.  EGR  can be accomplished by either reintroducing  exhaust gases into
the intake manifold (external EGR) or by restricting the exit  of gases that
would normally be exhausted from the cylinder (internal  EGR).   In both  cases
the effects  on pollutant emission are quantitatively the same.   Externally
recirculated gases can also be cooled before they are reintreduced into  the
cylinder.  Since these cooled gases are able to absorb more  heat than
unrecirculated exhaust gas would, the peak combustion temperature is lower and
less NOX is  generated.
       A previous study showed that cooled, external EGR was effective  in
reducing NOX from a large-bore, two-stroke blower-scavenged test engine^).
                                   4-112

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Although this engine was a two cylinder, older version of a locomotive
diesel, trends observed on it should be similar to those that would be
observed on modern production engines of this model.  The application of 20
percent cooler EGR at rated conditions resulted in a 55 percent NOX reduction
and an increase in smoke to 17 percent opacity.-   HC emissions were unchanged
and CO emissions were increased 72 percent.  By comparison,  20 percent hot
EGR resulted in NOX reductions of 51 percent at rated conditions and smoke
increased to 27.5 percent opacity.  HC emissions were reduced 17 percent and
CO emissions were increased 167 percent.
       These same trends have been reported in tests of cooled EGR on truck
sized engines which achieved NOX reductions of 60 percent using 15 percent
cooled EGR(96).  Smoke increased 300 percent and HC remained relatively
independent of EGR rate.  CO also increased at EGR rates greater than 30
percent.
       Since the oxidation of CO and HC depend upon the availability of
excess air and elevated temperatures, one might expect the reduction of both
oxygen and temperature by EGR to lead to increased emissions of these two
pollutants.  However, EGR traps or recirculates some of the  unburned, quench
layer hydrocarbons in the cylinder.   Since these recirculated remnants of the
fuel are combusted during the next cylinder firing, HC emissions frequently
decrease when EGR is used.   Smoke levels increase with EGR due to the
reduction in excess air.
-'Twenty percent EGR means that 20 percent of the exhaust gas  is  returned
  to the engine intake manifold.
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       As mentioned earlier, EGR systems can be grouped into two basic categories,
internal and external.  The application and associated operational  problems
of each will be discussed in the following sections.

Internal EGR
       With Internal EGR, the exhaust products are retained in the  cylinder by
increasing the exhaust back pressure, retarding the valve timing or by
reducing the scavenging airflow in two-stroke engines.  The exhaust back
pressure can be increased by inserting a restriction in the exhaust gas flow
to raise the pressure in the exhaust manifold.  This prevents the latter
portion of the exhaust charge, which normally exits at the lowest pressure,
from  leaving the  cylinder before the beginning of the next cycle.
       Retarded valve timing achieves the same effect by prematurely closing
s
the exhaust valves  and opening the intake valves.  The early closing of the
exhaust valve  prevents a complete purge of  the combustion gases, while the
quickened  opening of  the inlet  valve allows the trapped gases to enter the
intake manifold  and mix with the  air or air-fuel  charge before  reentering the
 cylinder.   The valve  timing in  all engine types  can be increased by changing
the  camshaft  timing (position of  the camshaft, which  controls the movement  of
the  valves relative to  the  crankshaft  and,  hence,  to  the  pistonjv9?).
        Reducing  the scavenging  air pressure in two-stroke  engines  results  in
 an incomplete removal  of  the  exhaust gases  by the fresh  incoming charge.   The
 scavenging air comes  fron  the  air box  located below the  piston  and is  driven
 through the combustion  volume by the blower.  The scavenging air pressure  can
 be reduced by bleeding  off sane of the air through a  valve located in the
 side of the air box.   This results  in  incomplete scavenging of  the exhaust
                                    4-114

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products which are then trapped 1n the cylinder and dilute the charge during
the next cycle.
       Internal EGR  1s available for both two- and four-stroke engines,
either naturally aspirated or turbocharged.  It 1s usable to a greater extent
with turbocharged models due to their leaner operation.
       Increased valve overlap has not been adopted for  a variety of reasons.
First, severe fuel penalties accompany the use of this technique.   In
addition the Inlet valves can become fouled due to the flow of hot dirty
exhaust products over them, and the presence of extra Inert mass,  which
contains cold fuel during startup, can make starting difficult^98).
Presumably these two problems could be overcome by engineering modifications.
A more difficult problem to solve 1s that of Increased smoke generation  1n
dies el engines due to the reduced excess air available during combustion.
Unlike engines with external EGR or air box bleed, those with valve  overlap
cannot reduce the redrculatlon rate as the load Increases.   Therefore,  they
tend to emit smoke at high power settings.  Derating the engine to the point
where smoke becomes acceptable appears to be the only solution.
       Figure 4-36 shows the effects of Internal EGR on  a naturally  aspirated
gas engine, a blower-scavenged spark (gas) and a turbocharged diesel.  For
these three engines Internal EGR reduced NOX emissions from  4 to 37  percent.
External  EGR
       External EGR is  accomplished by ducting some of the exhaust gas from
the exhaust system to the intake manifold.   Its  effectiveness can  be
increased  by cooling the  hot exhaust gases before  they are  introduced  into
the inlet  manifold.   Generally this is done by attaching cooling fins  to the
recirculating duct  to transfer  heat from  the  gases to  the  environment.  The
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 data available from tests of external  EGR  on large  engines  are  Included 1n
 Figure 4-36, together with the results obtained  with  Internal EGR.  The
 results from three tests on gas,  dual  fuel,  and  dlesel  turbocharged
 models show reductions  varying from  25 to  34 percent.   These reductions were
 obtained with exhaust gas redrculatlon rates  of 6.5 to 12.0 percent.  The
 effect of applying different  amounts of EGR  on NOX  emissions and fuel
 consumption 1s shown 1n Figure 4-37.   NOX  reductions ranged from 10 to 22
 percent with 6 percent  EGR.   In general, fuel  consumption remains unchanged
 for EGR rates less than 12 percent.
        Because the available  oxygen  decreases with  Increasing load (I.e.,
 Increasing fuel  flow but  nearly constant airflow),   1t 1s most efficient to
 vary the EGR rate  with  load.   Therefore, 1f the engine 1s  expected to be
 faced with varying load demands,  1t should have a control  valve  1n the EGR
 system  regulated by a load sensor.  Such a system 1s pictured schematically
 1n  Figure 4-38.  Air-to-fuel  ratios are typically close to sto1ch1cmetr1c  on
 dlesel  truck engines when they operate  at rated power.   Therefore,  external
 EGR  systems  that have been Installed on truck engines  to meet  California
 standards  for  heavy duty vehicles  have  set  their  proportional  EGR  controls to
 shut  the  redrculatlng  passage when the engine 1s run  at full  throttle.
 Large-bore engines, on the other hand,  run  much leaner,  even  at  rated
 conditions;  therefore,  they could  benefit from EGR  though  they normally
 operate at rated power.
       The primary durability consideration for external EGR systens,
 especially when applied  to dlesel  engines,  1s  the accumulation of solid
 exhaust products 1n the  redrculatlng system.   When  EGR  1s applied to
naturally aspirated engines,  these  deposits build up 1n the ducts, on any
valves used to control the  redrculatlon  rate,  and possibly on the Intake
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 Load
sensor
                        Muffler
                          Hot exhaust
                              gas
                       Control/cutoff
                            valve

                                        Air or liquid
                                         cooled heat
                                          exchanger
Turbocharger
                      Cooled
                     exhaust
                       gas
                                        Inlet air
     Figure 4-38.  Simplified schematic of EGR system for turbocharqed
                   intercooled engine.
                              4-119

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valves.   However,  when  external  EGR  is  used  in  conjunction with a
turbocharged and intercooled engine,  the  problems are magnified.  Since the
inlet charge, after the compressor,  is at a higher  pressure than the exhaust,
one either has to provide a separate  compressor  and inter cooler for the
recirculating stream or one has  to mix the  recirculated  gases with the
incoming air before they pass through the turbocharger.   Both approaches  have
similar problems, namely fouling of  the  compressor  blades  and the heat
exchanger surface^0^'^^).  If  the  compressor is designed to operate  close
to its optimum condition, its performance is very sensitive to the shape  of
the blades,   and these would be changed slightly  by  deposit build-up.
Similarly, the effectiveness of  heat exchangers  is  reduced greatly by  any
slight coating on the surface^102).   In fact,  moderate  deposits  can make  the
heat  exchanger virtually useless.  Such  deposition  problems do not
necessarily  preclude the use of EGR  on these types  of  engines, but they would
require significantly increased maintenance by the  user.
       Two studies have been conducted which evaluated  the deterioration  of
EGR systems  in heavy duty diesel and gasoline engines(103»104).  The external
EGR system evaluated in a diesel engine showed no  increase in NOX emissions
over  1000 hours  of use.  In contrast, the external  EGR  system  of  a  gasoline
engine fouled the carburetor and EGR passages after 700 hours  of  use.  The
significant  difference between these systems was the relatively  high
temperature  of the recycled exhaust gas  (approximately 600°F)  in the  diesel,
which prevented  the condensation of exhaust products in the  air  charging
system.  However some  condensation will  always occur,  and, therefore,
trouble-free operation of  any EGR system will involve increased  maintenance.
       One  engine manufacturer has also expressed  concern over the  con-
tamination  of  lubrication oil in EGR equipped large engines(105).   This
                                   4-120

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 problem has not occurred in current  production automotive  EGR  systems,
 presumably because of their lower  cylinder  pressures  and their use of  a fuel
 with a lesser tendency to form sludge  (sediment  in  engine  oil).
 4.4.7  Water Induction
        The addition of water  to the  fuel-air  charge has much the sane  effect
 as EGR.  It increases the inert mass of the charge  and results in lower NOX
 production through  decreased  peak  combustion  temperatures.  Although it is
 easier to insure  uniform mixing if steam is used, the water can be more
 effective if it is  injected as  a liquid.  Energy extracted from the products
 of combustion to  vaporize the water  causes an additional reduction in the
 peak cylinder temperature.  Furthermore, steam is usually not readily
 available,  and no test  data have been reported on the  use of steam.
 Therefore,  the  remainder  of this discussion is restricted to water in the
 liquid  phase.
        Nitrogen oxide reductions that have been achieved with water  induction
 are  shown  in  Figure 4-39.  The effectiveness of the technique appears  to
 correlate with  an absence of excess air.   Since the  purpose of  adding  water
 is to reduce the peak temperature by increasing the thennal mass  in the
 cylinder  (amount of material that is heated  by the  energy released during
 combustion), this technique should  be more  effective in  a low excess  air
system  than in one with much excess air and,  hence,  much  thermal  mass.  As
shown in Figure 4-39, the gas  engines,  which were the most  responsive to the
addition of water,  operated at lower  air-to-fuel  ratios  than  did the diesel
or dual-fuel units.   Presumably the excess air in the  latter two types  of
engines absorbs all  the heat  that can be transferred to  a fluid in the  short
time between ignition and peak  temperature.  The  combustion reactions for HC
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 are  inhibited by the lower temperatures, and,  therefore,  HC emissions
 increase with water induction^**),  increased quench layer effects  at  these
 lower cylinder temperatures may also contribute to the higher  HC emission
 rate.  CO emissions are largely unaffected by water Induction.
       Water induction can be accomplished in a variety of  ways  ranging from
 introducing it with the intake air to injecting it directly into the
 cylinder.  These systems vary in both complexity and effectiveness.  The
 effectiveness of the system is strongly a function of the degree of
 atomization and mixing of the water within the combustion charge.  The  best
 systems are those which provide for induction  prior to the  turbocharger, if
 present, or spray injection into the inlet manifold or cylinder  directly.  To
 control the water flow at various loads, a water pumping  and metering system
 (similar to the fuel system) must be provided.
       The reported effectiveness of this control  method  in reducing NOX
 emissions depends almost linearly on the rate  at which water is  added(107).
As shown in Figure 4-40 reasonable reductions  (e.g.,  more than 30 percent)
 for  large-bore engines are obtained only if the  water flowrate is at least
one-half the fuel flowrate,  and significant reductions require that  the rate
of water addition approximately equal  the fuel  flowrateUOS).  Data  with
water-to-fuel  ratios greater than 1.0 are available only  for high speed,
truck-si zed engines, but the same trends should  apply to  large-bore  engines
 as well.   As Figure 4-4l(109)  illustrates,  the  effectiveness of water
induction (percent NOX reduction per mass of water)  decreases as  the water
flowrate is increased  beyond 1.0.   This figure  also  confirms the  earlier
statement that  the effectiveness of water induction  is inversely  related to
the amount  of excess air present;  greater NOX reductions  are achieved (at any
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given water-to-fuel  ratio)  with the  engine  running  at  higher  load and,
consequently,  lower  air-to-fuel  ratio.
       Since many engines are used 1n remote,  and frequently  arid,  locations,
water availability may be a problem.  Assuming the  use of  a  1.0 water-to-fuel
ratio, a typical large-bore 600-hp engine would consume water at the rate of
0.46 gallons per minute (1.75 liters per minute), or  about 660 gallons  per
day in continuous operation, and a 4300-hp  unit at  the rate of 2.9  gallons
per minute  (11.0 liters per minute), or about  4200  gallons per day  in
continuous  operation.
       All  of the large-bore engine manufacturers who provided results  from
tests with  water induction  (General  Motors-END, Ingersoll-Rand, Cooper-
Bessemer, and White  Superior) reported serious concern about  the adverse
effects of  this technique on engine durability.  This concern was  based on
observations of water in the crankcase, which  contaminated the lubricating
oil(110)t ^d on rapid build-up of mineral  scale around the  valves, water
Injection nozzles and other components  (e.g.,  the turbocharger) through which
the  water flowed^11).  The one independent researcher who applied this
technique to a  large-bore  engine experienced the same oil  contamination^2'.
Only one  long  duration test (23 hours) of  the  use of water induction in a
large-bore  engine has been  conducted to  date,   and this program used untreated
water  (400  ppm  calcium carbonate)(113).  All  other tests  were short —
usually less than 2  hours  of engine running time.
4.4.8  Combustion Chamber  Geometries
        Combustion chamber  redesign  is  the  control technique  having the
 greatest  potential  for reducing NOX emissions  from large-bore engines  with
 little or no loss in efficiency.   It  is  probably also  the technique requiring
                                    4-126

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 the  greatest amount of research and development, and could result in
 manufacturers changing their engine designs significantly, incurring
 substantial retooling costs.  Several years would be required by manu
 facturers to perform research and development work and to retool to  build
 engines having redesigned combustion chambers before they could be used to
 meet a standard of performance for new stationary engines,  Some combustion
 chamber designs which  might be applied to reduce NOX emissions  without
 significant Increases  1n  emissions of HC, CO  and smoke,  or fuel  consumption
 will now be discussed.
        The combustion  process  can  be Improved  by redesigning  chamber
 geometries to  increase  turbulence,  as  in  high  swirl  engines(114),  by  staging
 as in engines  with stratified  charge^1*),  or  piston  head  cavit1es(116),  or
 by a combination  of both,  as with  "squish I1ps"(117).  High swirl  systems  use
 modifications to  the design  of the cylinder and  Inlet ports to produce
 circulatory air motion  in  the  cylinder  during combustion.  Since these flow
 patterns  are conducive  to  good air-fuel mixing and, hence, efficient
 combustion,  delayed ignition timing can be used to reduce peak temperatures
 below those necessary for  NO formation with less production of unburned HC
 and  smoke.  Unfortunately, no data are available to compare the NOX emissions
 of a  low-  or medium-swirl   engine with those fron a high-swirl  unit when  both
 are retarded as far as  possible,  I.e., until smoke becomes excessive.   The
NOX emissions from the  high-swirl  engine should be higher than those  from the
 low-  or medium-swirl units with corresponding  ignition timing  and could  very
well  be harder  to  control;  the  improved mixing  promotes  rapid,  early
combustion and  hence high  temperatures  for a long period of time(118).
       All  of the  staged combustion designs  (precombustion  chambers, the  M-
systems,  and stratified  charge) as  shown in  Figures 4-42  to 4-44(119-122)
                                   4-127

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Figure 4-42.   Schematic of a current production precombustion
              chamber for a diesel  engine (Reference 119).
                       4-128

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  Main
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                                                                Prechamber
    Figure 4-44(b).  Schematic of a prototype stratified charge gasoline
                    engine  (General Motors Corp. design — Reference 122),
                               4-131

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operate in basically the same manner.   The  fuel  charge  is  introduced  into  a
cavity as a rich mixture and ignited.   Since  it  burns in the absence  of
excess oxygen, NO formation is inhibited.   This  burning mixture then  expands
into the main chamber where it mixes  with additional  air at reduced
temperatures.  Therefore combustion is completed in an  overall  lean mixture
at temperatures which are adequate for combustion  but below those required
for NO formation.  The stratified charge  concept has  been  applied only to
gasoline engines, and no reports  exist that document  attempts to use  any of
the other designs on the very large engines.   However,  there  is  no reason  to
believe that the application of the basic  combustion  principles  are  not
applicable to the very large engines.   The  squish lip (Figure 4-45(123))
design appears to reduce emissions both by aerodynamic  effects  and by staged
combustion(124).  The lip-shaped cavity in the piston head increases
turbulent mixing and also creates a vertical  flow pattern  which  recirculates
burnt  gases  through the combustion zone within the cavity. Thus  it
incorporates  a form of internal EGR'^5).
       The emission levels that have been reached by engines  with  these
various  combustion chamber geometries are shown in Figure  4-46(a)  (NOX
emissions) and Figure 4-46(b)  (HC and CO emissions).   Included  are results
from  some truck-sized engines  and other commercially available  units, such
as  engines with  precombustion  chambers.  Based on these data,  NOX levels ranged
from  2.7 to  7.5  g/hp-hr  and  CO levels from 1.3 to 4.1 g/hp-hr.   HC emissions
were  clustered  between  0.2 and 0.6 g/hp-hr for  all of the  engines.   Since
these  configurations result  in approximately 60 percent lower NOX levels than
observed in  open chamber engines,  and since no  large-bore units are currently
built  with these designs, they can be considered a potential  "control technique"
for the  large engines.   Although members of the DEMA have expressed concern
                                   4-132

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                                   combustion chambers.

-------
about their ability to adapt such designs to their engines^26),  the  problems
appear to be mainly of the kind that can be solved by application of  current
technology rather than of the kind that are technical  barriers.   In fact,  one
manufacturer of squish lip engines has stated that he sees  no  reason  why
squish lips could not be used on pistons of large-bore engines^2?).
Furthermore, the open literature contains at least one report  of  a large-bore
engine that has been modified to incorporate something akin to one of these
staged combustion designs, namely a variable geometry precombustion chamber
(Engine No. 34 in Figure 4-46).   However, the report  presented results  on  a
full-scale engine at rated loads only under laboratory conditions^28).
       It should be noted that most diesel  engine models manufactured by the
Caterpillar Tractor Co.  have precombustion  chambers.   However,  they consume
5 to 8 percent more fuel  than similar size  direct injection engines,  when
both, are designed by the same staff (i.e.,  equal  engineering sophistication)
to operate at maximum efficiency and to meet the  same emission
standards'^).  Precombustion chamber designs  were introduced  during a time
when fuel economy was a less significant factor than  maintenance  costs  and
adaptability to a wide variety of fuels. The pressure rise rate  is lower  in
these engines than it is in the  direct injection  versions because the
combustion is extended in time and space.  Therefore,  mechanical  stresses  are
also less.  Furthermore,  it is easier to initiate combustion in the rich
mixture within the small  volume  of the precombustion  chamber than in  the lean
mixture within the large  volume of the main chamber.   Hence the fuel  spray
pattern is not so critical,  and, therefore,  a wide variety  of  fuels can  be
burned without having to adhere  to a strict  maintenance plan.   These
advantages are now outweighed by the need to conserve fuel. Therefore,
Caterpiller is planning  to phase out precombustion chamber  engines within the
                                   4-136

-------
 next few years, and their competitors  plan  to meet more  stringent standards
 (e.g., California's 1975 and 1977 heavy duty vehicle  standards) without
 resorting to this design.
 4.4.9  Catalytic Converters
        The automotive  industry has  expended considerable research and
 development during the  past 5  years for  exhaust catalysts to reduce HC and CO
 emissions.  These catalysts, however,  are not  effective in reducing NOX
 emissions.  Catalytic  converters  that  reduce  NOX emissions have been
 developed and applied only  recently to  1977 model year cars(13°).   These
 systems  are called "three-way  conversion (TWC) catalysts since they reduce
 HC,  CO,  and NOX emissions simultaneously.  These TWC catalysts closely
 resemble the  earlier oxidizing  catalyst  (precious metals applied to monoliths
 or  pellets) with the addition of  rhodium which selectively reduces NOX to N2-
 To operate properly, the air-to-fuel ratio of the automobile exhaust under
 operating  conditions must be controlled to a narrow range about stoichio
 metric.  The  recent availability of durable ceramic exhaust  gas oxygen
 sensors  to determine A/F conditions and control logic systems to regulate the
 A/F  conditions  in the exhaust have made possible the implementation  of this
 control  system U31).  Figure 4-47 illustrates the  approximate location of
 this device on  an engine.
       These  catalytic systems, however, are not  applicable  to large-bore
 engines for two reasons: (1) HC and CO  emissions from  large-bore engines  are
relatively  low in comparison with vehicle level  (typically 0.1  to  0.5
g/hp-hr nonmethane HC and 0.2 to 5.0 g/hp-hr CO for  a  large  engine versus  1
to 6 g/hp-hr reactive HC and 30 to 90 g/hp-hr  CO for a  100-  to  200-hp
gasoline fueled engine)  (2)  A/F  conditions  in  the exhaust of  large engines
                                   4-137

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-------
are typically much greater than stoichicmetric.   Consequently,  other  approaches
which can selectively reduce NOX emissions in the presence of excess  oxygen
must be considered.
       One approach is to inject ammonia,  hydrogen,  CO,  or natural  gas  into
the exhaust to create the required reducing atmosphere(^2,133)t  Ammonia
appears to work best because it has an affinity for  the  NO rather than  the
excess oxygen.  That is, one needs to add  only slightly  more ammonia  than
would be required for stoichicmetric reaction with the NO, whereas  with the
other three substances, additional quantities  are required to  deplete  the
excess oxygen in the exhaust.  Because of the high cost  (see Section  8.2 1n
Chapter 8), even with ammonia,  no engine manufacturer  is investigating  the
reduction of NOX in 1C engines  using ammonia(^).
       One research laboratory has experimented with a combination  converter
scrubber exhaust treatment system for a two-stroke diesel  engine commonly
used in busesU35)t  NQX scrubbers are actually N02  scrubbers and are
ineffective for NO.  Since NO is the primary constituent of NOX in  the
exhaust, scrubbers cannot be used on engine exhaust  unless the  NO is
converted to N0£ first.  Therefore,  this laboratory  converted the NO  to N0£
by passing the exhaust through  a catalytic converter which also oxidized the
CO, HC,  and oxygenated HC (odorous gases)  to CO^ and water.  Since  the
exhaust gas temperature was  below the 700°F required by  the  converter for
proper operation,  the exhaust was first  passed through a heat exchanger to
raise its  temperature.   Finally the  oxidized exhaust gas  entered a  molten
carbonate scrubber where the NOX was reduced by approximately 50 percent
(reduction from 17.35 g/hphr to 9.2 g/hp-hr).   This  reduction fell  short of
the desired 70-percent  reduction (to meet  a 5 g/hp-hr  standard).  In
addition,  the cost of the system was judged unacceptable due to the high
                                   4-139

-------
price of the platinum catalyst ($15/lb) used.   With a system requirement  of
60 Ib of catalyst, the platinum catalyst,  alone,  would cost  approximately
$900.
       In conclusion, then,  catalytic reduction of NOX has  not,  as  of  the
present, been demonstrated as a viable control  technology for large-bore
stationary reciprocating engines.

4.4.10 Combinations of Controls
       Several  manufacturers have  conducted experiments  with more than one
control system at a time.   The results of  these tests are presented by fuel
in Figure 4-48.  Figure 4-48(a) indicates  that  the controls  are  nearly
additive for diesels.  Although a  greater  reduction is achieved  on  gas and
dual fuel engines by the combination of controls  than by any one of the
individual component techniques when used  alone,  the reduction is less than
the sum of the effects from each technique.
       Thus, for the large-bore diesel engine  shown in Figure 4-48(a)  the
maximum NOX reduction for  a single control  (retard) is 1.7  g/hp-hr.  When all
the controls tested (retard, reduced inlet  manifold air temperature,  in
creased air-to-fuel ratio, and water induction) were applied simultaneously,
NOX was reduced 3.0 g/hp-hr.  This is shown on  the figure as an  uninterrupted
downward arrow.  For comparison, to the left of this, is a multiple arrow
line that represents the depiction in series of all the  separate control  effects,
as they were individually measured.  The difference between  the  length of
these two lines is a measure of the relationship between the additive  effects
of the controls when applied simultaneously and the sum  of their individual
contributions.   As noted earlier,  for this  case the controls do  appear to
be additive.
                                   4-140

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        Figure 4-48(5) shows that the combination of retard and manifold air
 temperature reduction is nearly additive in  dual-fuel  engines,  but  the
 additional use of increased air-to-fuel  ratio does  not decrease NOX as much
 below the levels obtained by the first two  controls  as one would expect from
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                                                                            /\
 reduction were required  (e.g.,  25  to 30 percent)  for this  engine, one  would
 change the air-to-fuel ratio;  however, if a  greater reduction were  neces-
 sary one  would use the combined  controls  of  retard, manifold air temperature
 decrease,  and air-to-fuel  ratio modification.
        Gas engines  also  do  not  respond additively to the simultaneous
 application of  several controls  (Figure 4-48(c)).  Here reduced manifold air
 temperature decreased emissions from the blower-scavenged engine by 36
 percent, whereas  the application of  reduced temperature plus retard reduced
 emissions  only  29 percent.  Only the combination of the above two techniques
 with  increased  air-to-fuel ratio could reduce emissions below the level
 obtained by reduced manifold air temperature alone.
       The turbocharged engine reached its lowest level (7.4 g/hp-hr) with  an
 individual  control when the air-to-fuel  ratio modification was  used.
Although this engine was  controlled to 4.5 g/hp-hr by the simultaneous
 application of all three  controls,  if these  controls would have had  an
additive effect on the emissions, the engine would have emitted no NOV
                                                                     A
whatsoever.
       All but two combinations of  controls  resulted in a  greater reduction
than any individual technique.   In one gas engine the  combinations without
increased  air-to-fuel  ratio were not  as effective  as increased  air-to-fuel
ratio by itself.   Recent  tests  on installed  gas  pipeline engines  have shown
                                   4-144

-------
that increased air-to-fuel  ratio is the  most significant  source  of  NOX
reductions from large-bore  gas  engines(^6)t  jn tne other  case,  the
combinations without increased  air-to-fuel  ratio were not as  effective  as
increased aftercooling by itself.

4.4.11 Summary of NOX Reductions
       This subsection summarizes  the  data  presented in Sections  4.4.1  through
4.4.10 for control techniques that have  been shown to be  technically  viable
and effective in reducing NOX emissions. These techniques  include:   derate,
retard, air-to-fuel changes,  manifold  air temperature reductions,  exhaust
gas recirculation (EGR),  and  combinations of these controls.  With  the  exception
of EGR, all of these techniques consist  of  a change in an engine operating
condition.
       Although water induction has been shown effective  in reducing  NOX
emissions, no data have been  summarized, since this technique has  serious
technical limitations (see Section 4.4.7).   Furbhermore,  modifications  to
combustion chamber geometries (Section  4.4.8) and the application of
catalytic converters (Section 4.4.9) have been excluded from  this summary
since only limited data for large-bore  engines are available  for these
control approaches.  Nevertheless, both  of  these approaches have  been used
successfully on smaller bore, mobile engines.  In general,  however, these
techniques will require considerable development before they  can  be considered
technically viable considering  costs.  Turbocharging (see Section  4.4.4) has
not been listed as a control  approach  since most large-bore engines are already
turbocharged, and engine  users  are showing  increasing preference for  turbocharged
units because of their lower  initial costs
                                   4-145

-------
        A summary of  the NOX reductions achieved by the candidate control
 techniques  discussed above is presented on Figure 4-49.  The arrows on these
 figures  begin  at the uncontrolled NOX level and end at the controlled level.
 Dashed  arrows  indicate the same reduction after correction to standard
 ambient  condition  (85°F, 75 grains/ft3 humidity) (see Section 4.2.1.) The
 changes  in fuel  consumption after application of NOX controls are also shown
 in Figure 4-49.  Figure 4-50 shows uncontrolled NOX levels and the  lowest
 controlled level for each manufacturer of diesel,  dual-fuel,  and  gas  engines.
 Note in Figure 4-50 that some of the engines show only uncontrolled emissions
 since no control techniques had  been applied.
       A NOX control data summary appears in Table 4-13 based on  Figures
 4-65 through 4-70.   This table also shows uncontrolled levels and the lowest
 controlled level for each  kind of control  technique  as applied to each  engine
type and fuel combination.   These data are summarized  in  a  different  way in
Table 4-14.
       t   Uncontrolled levels for  dual-fuel  engines  are  generally  lower than
           for  diesels,  which  are generally lower  than for  gas  engines
       •   Diesel,  dual-fuel,  and 2-TC gas  engines more  consistently  achieve
           lower NOX levels than  do  4-TC  gas  engines.   For  example, at  least
           one  turbocharged diesel,  dual-fuel,  or two-stroke  gas  engine  is
           capable  of  reaching a  NOX  level  of  6 g/hp-hr.  In  comparison,  the
           lowest NOX  level  (corrected for  ambients) demonstrated by  any for
           which  data  are available  is 9 g/hp-hr.
       •   In general, the  data show  that two-stroke turbocharged gas and
           diesel engines have reached  lower levels than  blower-scavenged or
          naturally  aspirated engines.  No trend is apparent for the same
          comparisons of four-stroke  diesel and gas engines.
                                  4-146

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unconnected f
V Controlled N0x art>ients
i
A T Q Q . ;
A A Q Q Q D
*— •
G>


• 0 0
• o -
t * -
T A •-
T t '•• 1

~ ~
^ v 0 *
-
-
1 r
4 20 23 25 28 29 37 38 40 45 46 48 49 53 54 81 82
2340176402139 	 	 -3555
31 42 38 61 6 88 — — — 55 27 — — - 	
A R 0* D R A - — — OR
4-TC
                    Figure 4-50(c).  Uncontrolled and maximum controlled  NOX levels for gas engines.

-------
                 TABLE 4-13.   SUMMARY OF LOWEST NOX LEVELS (g/hr-hr)  FROM CONTROLLED LARGE-BORE ENGINES
Fuel
Strokes/Cycle
Air Charging
Uncontrolled
Derate, D
Retard, R
A/F, A
MAT, M
Internal EGR, IE
External EGR, EE
R+M
R+A
D+M
A+M
R+M+A
Best Control
Diesel
2
BS
14.6-17.8
13.8
10.6
~
~
—
~
~
~
~
~
~
10.6
TC
8.5-14.7
9.0
5.6
—
—
—
6.6
—
7.0
~
8.0
~
5.6
4
NA
8.7-10.0
10.7
—
—
—
—
—
—
--
—
—
—
10.7
TC
5.2-15.2
7.1
3.0
6.3
6.2
7.1
—
6.2
2.6
14.2
6.3
8.7
2.5
Dual Fuel
2
TC
6.9-13.4
—
2.5
6.3
5.0
—
6.5
—
—
—
—
~
2.5
4
TC
4.4-12.1
7.3
8.5
5.8
7.7
~
—
7.0
—
—
--
5.5
3.8
Gas
2
BS
11.5-15.1
3.8
12.8
14.7
9.6
9.5
~
10.6
—
~
—
8.7
4.4

TC
8.6-17.7
4.4
11.8
7.4
8.3
—
5.8
8.1
9.8
—
—
4.6
4.4
4
NA
14.0-29.0
6.0
27.9
20.5
~
14.4
~
~
10.9
~
--
~
6.0

TC
7.8-22.3
8.6
10.0
2.0
12.0
—
—
~
—
--
—
~
2.0
cn
co

-------
TABLE 4-14.  NOX EMISSIONS FROM VARIOUS GROUPINGS
             OF ENGINES
Group
Air charging
Turbocharged
Nonturbocharged
Strokes/cycle
2
4
Fuel
Diesel
Dual Fuel
Gas
Emissions, g/hp-hr
Uncontrolled
4.4-22.3
8.7-29.0
6.9-17.8
4.4-29.0
5.2-17.8
4.4-13.4
7.8-29.0
Controlled
2.0-5.6
3.8-10.7
2.5-10.6
2.0-10.7
2.6-10.7
2.5-5.5
2.0-6.0
                  4-154

-------
         Since  emission  levels from uncontrolled engines vary so widely, the
  environmental  impact depends more on the percentage NOX reduction it produces
  than on  absolute NOX level  it achieves.  Therefore, the data shown in Figure
  4-49 have been recost  in terms of percentage NOX reductions and summarized
  in Table 4-15.  A number of techniques, either alone or in combination,  are
  capable of achieving NOX reductions  of 20 to 40 percent with moderate increases
  in fuel consimption (less than 10 percent).   In general,  retard,  air-to-fuel
  ratio changes, or combinations of these two  techniques  achieved  greater than
  40 percent NOX reductions.
        In addition to these techniques,  combinations  of retard  and manifold
  air cooling produced similar results  for gas  and  dual-fuel  engines.   As shown
 in Figure 4-49,  a number  of  turbocharged diesel,  dual-fuel  and gas engines
 achieved 20 to 40 percent NOX  reductions with  less  than a  10-percent  increase
 in fuel  consumption.  Thus,  several techniques  can  effectively reduce NOY
                                                                        A
 emissions  from diesel  large-bore.  With  the exception of controls applied to
 dual fuel  engines,  however,  maximum NOX  reductions  are accompanied by large
 increases  in fuel  consumption.
       Figure  4-51 presents  an overview  of the fuel penalties associated with
 the various NOX control techniques.  Based on the data shown in Figure 4-51,
 large-bore diesel engines typically suffer a fuel  consumption increase of
 somewhat less  than 1 percent for each g/hp-hr of NOX reduction.   The  major
 deviations fron this average figure are manifold air temperature reduction,
which in some  cases actually causes fuel  consimption to  decrease,  and
derating which is accompanied by higher than  average fuel  penalties.
Retard,  whether used alone or in combination  A/F ratio changes,  causes  the
largest  fuel  penalties,  but  also  achieves the lowest NOX levels.
                                   4-155

-------
                       TABLE 4-15.   ALTERNATIVE CONTROL TECHNIQUES - SUMMARY OF SELECTED CONTROLS
-o
I
Ul
01

% NOX Reduction
£20
20 and <40
>40
Maximum
reduction (%)
Diesel
Control
A, M, IE,
RMA, D, R,
EE, RM, RA,
AM
D, EE, RM,
AM, R, RA
R, RA
RA (65)
ABSFC, %
1 to 8
1 to 16
8 to 26
26
Dual Fuel
Control
EE, D, R,
A, M, RM,
RA, RMA
D, A, M,
RM, RMA, R,
RA
R, RA
R (73)
ABSFC, %
0 to 4
1 to 7
2 to 5
3
Gas
Control
D, R, A, M,
IE, EE, RM,
RA, RMA
R, M, IE,
EE, RM, D,
A, RA, RMA
D, A, RA,
RMA
D (90)

ABSFC, %
0 to 5
0 to 8
5 to 12
12

-------
                    9200
                    8800
                    8400
                  L 8000
                  -I.
-p.
I
en
                    7600
                  o.
                  £
                  3
                    7200
                    6800
                    6400
                    6000
                                                                                              #10
                Diesel

                Q 2-BS

                Q 2-TC
                & 4-NA

                ^7 4-TC
                D  Derate
                R  Retard
                A  Air-to-fuel ratio
                M  Manifold air temperature
                IE Internal EGR
                EE External EGR
                CR Compression ratio
                                                          10      12       14

                                                          NOX level, g/hp-hr
16
18
20
                          22
                          24
                             Figure 4-51(a).   Fuel  consumption versus controlled NOX level for diesel enqi
                                engines.

-------
                                                         8ST-1?
                                            Fuel  consumption,  Btu/hp-hr
               O
               O
               O
                           §
                           o
i
ro

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                                                                    33
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                                                                                  2
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                                                                                               a
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              INJ
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-------
    9200
    8800
    8400
    8000
    7600
 _  7200
 1

    8800
   6400
   6000
EE
                             R.A.CR
                                                Gil
                                              O  2-8S
                                              Q  2-TC
                                               0  Dtritt
                                               R  Rltird
                                               A  A1r-to-fu«l rit(o
                                               N  Mvrifold ilr tMip«riturt
                                               EE  Exttrnil EGR
                                               IE  Inttrml EGR
                                              CR  CMiprtiiton ritlo
                                                           163
                                    0      I?      14
                                     NO, livtl, g/hp-hr
                                                    20      22
   9200
   8800
   8400
   8000
=  7600
-  7200
  6800
  6400
  6000
                                              RtAl
                                                           29..144
                                                   811
                                                    &  4-NA
                                                    7  4-TC
                                                    D  Dtrit*
                                                    R  Rttird
                                                    A  A(r-to-fMl ritlo
                                                    H  Ntnlfold ilr U«p«rtturi
                                                    IE  Intirnil EOR
                                                                                 29.,144
                                          NO, Itvil, g/hp-dr
                                                              18      20     22     24      26
  Figure  4-51(c).    Fuel  Consumption  versus  controlled  NOx  level
                            for  gas  engines.
                                  4-159

-------
        Fuel  consumption increases slightly more than 1 percent per g/hp-hr
 of NOX  reduction in dual-fuel engines.  Derating again results in the worst
 fuel  consumption penalty per unit NOX reduction.  Large-bore gas engines show
 the widest range of fuel consumption variation with the use of controls.
 Fuel  penalties range from slight improvements to a maximum of 1.8 percent
 per g/hp-hr  of NOX reduction.  In general, reduced manifold air temperature
 causes  the least fuel consumption increase per unit NOX removed.   Air-to-fuel
 ratio changes and combinations of A/F change and retard cause the largest
 fuel  penalties per unit of NOX reduced.
       The techniques summarized here and their effectiveness, their fuel
 penalties, and the time required to implement them will be discussed further
 in Chapter 6.

 4.4.12  Effects of NQy Controls on HC. CO and Smoke
       This  section discusses the effect of the application of -;he NOX
 controls on  the criteria pollutants HC,  CO, and smoke.   The purpose of this
 discussion is to insure that NOX emissions can be reduced  by the techniques
 discussed above without unacceptable increases in emissions of these other
 criteria pollutants.
       The effect of NOX control systems on hydrocarbons  is shown graphically
 by fuel  in Figure 4-52.  It should be noted that only about 10 to 25 percent
 of the hydrocarbon emissions from gas and dual-fuel  engines are reactive
 (i.e., criteria hydrocarbon pollutants), the remaining 75  to 90 percent  being
 unburned methane (see Appendix C.4 and Reference 138).   In contrast,  over 90
 percent  of the total  hydrocarbon emissions from diesel  engines are
 reactive(^9)j S1-nce  ,j-jese]  fuel is composed of higher order hydrocarbon
molecules (i.e.,  there are many hydrogen and carbon  atoms  in each molecule).
                                   4-160

-------
cr»
                       .8
                       .7
                       .6
                   £  -5
                    i
                   OL
                   -C
                   cn
                   ,-"  .4
                   O>
                   o
                   re
                       .3
                       .2
                       .1
                                              IE §27
                                                                                    'fn
                                        R&A
                                                           10      12       14        16
                                                                  NOX level, g/hp-hr
18
           Diesel
           O  2-BS
           Q  2-TC
           A  4-NA
           ^  4-TC
           D " Derate
           R   Retard
           A   Air-to-fuel ratio
           M   Manifold air temp.
           IE  Internal EGR
           EE  External EGR
           CR  Compression ratio
                                                                                                                       i
                            Figure 4-52(a).   HC levels versus  controlled  NOX levels  for diesel
                 22
              engines.
24

-------
t   5
!
      - R
                  R&M
Dual Fuel
Q 2-TC
^T4-TC
D  Derate
R  Retard
A  Air-to-fuel ratio
M  Manifold air temp.
EE External EGR
                              8      10
 12       14       16
^ level, g/hp-hr
18       20       22
                    24
      Figure 4-52(b).   HC levels versus controlled  NOX levels for  dual-fuel  engines.

-------
I   4
             EEU
                                                           til
                                                          0 MS
                                                          Q 2-TC
                                                          D Dtritt
                                                          R Retard
                                                          A Atr-to-fuil ntto
                                                          M Mint/old Itr temp.
                                                          EE External COR
                                                          IE Inttrml EAR
                                10      U     14
                                    NOX livtl, g/hp-hr
                                                    16     IB     20     22
                                                                             24
                                                             Gas

                                                             & 4-NA
                                                             ^ 4-TC

                                                             D Derate
                                                             R Retard
                                                             A Atr-to-fuel ratio
                                                             M Mantfold atr tmp.
                                                             IE Inttrnal EGR
                               10      12      14     16     18
                                       NOx level, g/hp-hr
                                                                20     22
   Figure  4-52(c).
HC  levels  versus  controlled NOX  levels
for  gas  engines.
                                4-163

-------
Therefore,  the reactive  emissions  from most  engines  range  between 0.1  and 0.5
g/hp-hr,  independent of  fuel.   These  values  are  nearly  an  order of magnitude
lower than  corresponding numbers for  uncontrolled  automobile  engines and
within a factor of two from the ultimate statutory limit of 0.41 gHCt/mile.-'
       Furthermore,  as discussed  in Appendix C.4,  the ratio of reactive
hydrocarbons to total hydrocarbons remains,  in  general, unchanged after the
application of derate, air-to-fuel,  retard,  manifold air cooling, and  EGR.
Thus, reactive hydrocarbon levels  respond in the same manner  as the total
hydrocarbon levels illustrated in  Figure 4-52.   Therefore, the remaining
discussion will consider only total  hydrocarbon  emissions, since these are
what most manufacturers  have measured and reported.
       With the exception of three four-stroke,  turbocharged  engines (Engines
No.  6, No. 16, and No.  4), one gas and  the  other  two  dual-fuel, the
hydrocarbon emissions do not change much due to the  application of NOX
controls.  Thus, among the diesel  engines, HC emissions generally change  by
less than 0.1 g/hp-hr.  These changes can be either  increases or decreases
from the starting levels of 0.15 to 0.5  g/hp-hr prior  to the  application  of
NOX  controls  (Figure 4-52(a)).  The two-stroke  dual-fuel  unit (Engine  No.  13)
with low emissions of HC experienced at  most a 1 g/hp-hr  increase  in HC
emissions from a baseline level of about 1.5 g/hp-hr.   Again  the application
of  some NOX controls  did not cause the HC emissions  to increase  (Figure
4-52(b)).  Control of NOX has a similar  effect  on HC emissions from  gas  engines
(Figure 4-52(c)) as  it does on these emissions  from  dual-fuel units.   As  will
be mentioned  in the  next section (4.5),  methods exist for  reducing
— Conversion from g/roile to g/hp-hr based on automobile fuel consumption
   rates of 15 miles/gallon on the road and 0.6 Ib/hp-hr on an engine
   dynamometer.
                                   4-164

-------
hydrocarbons from large-bore engines.  Therefore, it should be possible to
reduce the HC emissions from the three high emission four-stroke,
turbocharged engines.
       Similar graphs are shown for CO variations due to the application of
NOX controls in Figure 4-53.  These graphs show that the incremental  changes
in the CO emissions generally are less than 2 g/hp-hr.  Thus,  for  the diesel
engines shown in Figure 5-27(a), CO emissions increase by less than 0.5 g/hp-
hr when the uncontrolled level  is low (i.e.,  around 1 g/hp-hr) and by 1
to 2 g/hp-hr when the uncontrolled levels are higher (3 to 7 g/hp-hr).   One
exception to this trend is engine No. 60, which is turbocharged.   Reductions
in its air-to-fuel ratio caused a large increase in CO emissions.
       Similarly, dual-fuel engines that are  relatively low emitters  of CO
experience little changes in these emissions  due to the application of  NOX
controls whereas those units that start from  a higher level  show greater
changes.  Specifically,  the three engines whose controlled level  is around
1.5 g/hp-hr show changes that range from no increases to increases of less
than 0.5 g/hp-hr.  In contrast,  the two four-stroke  units whose uncontrolled
emissions are 3.6 to 4.5 g/hp-hr react to the application of NOX controls
with CO changes that range from  a decrease of about  2 g/hp-hr  to an increase
of 3 g/hp-hr.   With the  exception of Engine No.  21 (naturally  aspirated),
all the gas engines shown in Figure 4-53 experience  CO increases less than 1
g/hp-hr when controlled  to reduce NOX.
       Since the baseline CO emissions  from large-bore engines  are low,  at
least by comparison with automobiles,  these incremental  changes can represent
large percentage increases,  frequently as high  as  100 percent.  The highest
CO values  recorded probably can  be reduced  by increases  in the  air-to-fuel
ratio along with the control  techniques  used  (usually retard and/or increased
                                   4-165

-------
i
i-»
cr>
                         $
o.
JC
en
H   3

-------
                                                                      Dual Fuel
                                                                      O 2-TC
                                                                      t» 4-TC
                                                                        D Derate
                                                                        R Retard
                                                                        A Air-to-fuel ratio
                                                                        M Manifold air temperature
                                                                       EE External EGR
                                                                          20
22
                                                                                           i
                                                                                           <
                                                                                           24
                                    NOX level, g/hp-hr
Figure  4-53(b).   CO emissions  versus controlled NOX  level for dual-fuel engines.

-------
  10
s
                                                       Gas
                                                      O 2-B
                                                      Q Z-TC
                                                       0 Otratt
                                                       ft Rttird
                                                       A A1r-to-fu«l ratio
                                                       M Hanlfold air temperaturi
                                                      EE Enttmal EGR
                                                      IE Intemil EGR
                               10      12      14     It
                                     NO, levtl, g/hp-hr
                                                          18     20     22
  77.
  16
  10
_•  e
I
      129
                                             129
                  &	»-29.
                                      Gas
                                    & 4-NA
                                    ^ 4-TC
                                      0 Derate
                                      R Retard
                                      A Air-to-fuel ratio
                                      N Manifold Air Temperaturi
                                     IE Internal EGR
                                                                          to 29.0, «44
     Figure 4-53(c).
  10     12      14     16      18      20     22      24
      NOX level, g/hp-hr

CO emissions  versus  controlled  NOX
level  for  gas engines.
                                   4-168

-------
  Inlet air cooling).   With  this  in mind,  and  if  one  excludes the two-stroke,
  blower-scavenged  diesel  (Engine No.  17), the four-stroke turbocharged diesel
  (Engine  No.  60),  the  four-stroke turbocharged dual  fuel (Engine No. 16), and
  the four-stroke naturally  aspirated  gas  engine  (Engine No. 21) that achieve
  neither  low  NOX nor low CO  levels (excluding the dual fuel unit),  all  the
  data  points  for engines with NOX controls fall below 4 g/hp-hr.
        Presumably CO  emissions  would be reduced from the four-stroke,
  turbocharged engine (all fuels) as a consequence of any attempt to reduce HC
  from  them.  However,  if one excludes the data points for Engine Nos. 5,  6,
  15, 16, 28 and 60, all other turbocharged engines  could meet  a 2  g/hp-hr
  limit on CO, even  when controlled for NOX.   These figures  are  significantly
  lower than the federal standards of  40 g/hp-hr on heavy duty vehicles^140)  or
  even than the proposed 1977 California standards of  25  g/hp-hr(141).
        The plumes  from most well maintained  large-bore  engines  are  virtually
  invisible when  the engine is operating at a  steady state.  However, excessive
 retard or large EGR  rates  will  cause  diesel  and  dual-fuel engines to emit
 smoke.  Visible emissions  usually were  not measured  during experiments with
 NOX control  systems.   In most  cases the manufacturers observed the exhaust
 visually  and  simply  did not  measure emission  rates after the plimes become
 significantly visible.  If the manufacturer did report smoke readings,  along
 with NOX  reduction due  to the  application of  potential controls, the NOX
 control results were used in this document only  if the plune  did not exceed
 10-percent visibility.
       Figure 4-54 shows the relationships between smoke emissions  and  N0¥
                                                                         A
 reductions for those engines where data were  reported on both pollutants.
All of the engines  were diesels with  the exception of one dual-fueled unit
(Engine No. 16). The smoke  levels  ranged from 1.5 to 8  percent opacity or
                                   4-169

-------
                                                            4-NA
                                         Dual  fuel


                                         Diesel
                                               4-TC
                                               V
                   o
                   a.
s
                   o
                   to
                   CO
                    o
                   00
                                                                       D   Derate
                                                                       S   Increased  speed
                                                                       A   Alter air-to-fuel
                                                                       M   Manifold air temperature
                                                                       E   External EGR
                                                                       H   Water induction
                                                                       I   Internal EGR
                                                                       CR  Reduced compression ratio
                                                                       R   Retard  ignition
                                                                       BS  Blower  scavenged
                                                                       NA  Naturally  aspirated
                                                                       TC  Turbocharged

                                                                       NOTES:
                                                                       1.  Engine code number denotes
                                                                           initial point.   Control code
                                                                           denotes level  after control.

                                                                       2.  Bacharach  and  Bosch meters
                                                                           are filter-type  instruments.

                                                                       3.  Smoke levels  for engines #8-#12
                                                                           were measured  with a Bosch meter.
                                                          #27
                       10
%«

>i
                    ex
                    o
                                 #34

                                 J
                                  D
                                                     CR 18  19
                                                                                                                           #10
                                                6          8          10         12

                                                                 NOX level, g/hp-hr
                                                                         14
16
18
20
                            Figure  4-54.   Smoke  levels versus  NOX  levels for large-bore  diesel  engines.

-------
  Bosch Smoke Spot Number 2 to 3 for uncontrolled engines.9/  Since NOy
                                                         ^™           rt

  controls which caused smoke levels to exceed 10 percent opacity were not

  considered as acceptable,  none of the data points for controlled engines are
           K
  above this} value.  However,  the effect of progressive application of retard

 or EGR on smoke is demonstrated best by data which include higher smoke   \

  levels.  Such data are presented in Table 4-ie(142) for two different  diesfl

 engines (b|oth two-stroke)  and substantiate the  above assertion that  smoke  ''

. increases  'as  either the  percentage of exhaust gas  recirculation or the  degree

 of retard  is  increased.  The  table also shows the  effect  of engine (i.e.,

 stack)  size on opacity.


 4.4.13   Combustion  of Nonstandard  Fuels

       Although most  stationary 1C engines  burn No.  2  distillate  or  pipeline

 quality  natural gas,  both of  which contain  less than 0.3.percent  sulfur  (by

 weight), engines  are  occassionally sold for applicationsvwhich  use residual

 oils  or  unprocessed natural gas.   The  primary air  pollution concern with the

 use of these fuels is their potential for causing  high SOX emissions, since

these fuels typically contain more sulfur then do the distillates and
                                                                  ^f
processed natural  gas.  This section briefly reviews those applications  that

use nonstahdard fuels and their missions.
9/
_ Since the Bosch Smoke Spot Number is a measure of the soiling
  characteristics of the particulate and is measured by the  darkness  of
  the spot, of particulate collected on a piece of filter paper,  its  value
  in any g.tven test depends upon such  factors  as stickiness,  color,  and
  reflectence of the particulate.   Opacity,  on the other hand depends  on  the
  size distribution of  the  particulate,  which  affects  the  pi line's-ability ,'
         nlh-  *!*? the  Fussage  of  light'   Therefore, there is  no general
         nship between  the  two  systems.
                                  4-171

-------
  TABLE  4-16.   RELATIONSHIP BETWEEN SMOKE, EGR, RETARD,
               AND  ENGINE SIZE
Engine Type3
2-BS-D







2-TC-D



Control b
None
10% EGR
20% EGR
30% EGR
4° advance0
None
4° retard

None
4.9%
8.4%
12.1%
Opacity, %
4.7
12
27.5
59
2.7
4.6
10
6 Cylinder 12 Cylinderd
7.5 11.0
10.0 14.0
11.5 16.7
14.8 21.4
 Blower-scavenged engine  is  two-cylinder test engine with
 needle  valve  injector  (from Reference 142).  Turbocharged
 unit is Engine  No.  12.
DA11  EGR data  based  on  hot EGR.
'Injection  advance is not a  control; data included to
 show trend.
 Computed from six-cylinder  data using Beer Lambert law
 (see Figure 8-1), double the stack cross sectional area
 (to  accommodate doubling of exhaust volume), and the same
 particulate concentration (mg/m3) as in six-cylinder unit.
                    4-172

-------
   Seme  of  the more  common  applications of engines using unprocessed natural
   gas are  sewage treatment plants.  The engines at these facilities often burn
   sewage digester gas.  Although the sulfur content of this gas varies,  typical
   values range from 100 to 150 ppm of hydrogen sulfide (H2S)(143).   This level
  translates into an emission rate of less than 0.5 g/hp-hr of S02  (assuming
   600 Btu/ft3 gas and a fuel  rate of 7500  Btu/hp-hr).   Emissions  data shown
  in Table 4-17(144) for a sewage plwt  jn LQS  Angeles>  however>  indicate that
  some engines  emit  as much as 1  g/hp-hr of  S02U45).   These  levels  are  well
  below  the estimated 2 g/hp-hr  emitted from  a  diesel  engine  burning  0.5  percent
  sulfur distillate  (see Section  4.1.6).W
         Stationary  reciprocating engines  occasionally are  sold with the
  capability of  burning  residual  or  crude  oils.  The only known domestic  site
  where  stationary 1C  engines  are burning residual oil  is the Anamax Mining
  Company diesel electrical generation plant near Tucson, Arizona^).  This
  installation was designed to take advantage of the lower cost of these heavy
  oils as well as their availability at that site.  Distillation of  crude oil
  produces  distillates which are relatively low  in sulfur content  and,  hence,
  concentrates any sulfur present in the  crude into the residual  oil.   The
 sulfur  content  of  crude and  residual  oils depends  on  their source  and,  in the
 case of residual  oil,  on how severely the parent  crude  is  distilled.  Table
 4-18(147)  ir)d1cates sulfur contents  of crude oils from  various sources.
        The naturally low sulfur, or  "sweet", crudes and their residuals may
 have  sufficiently low sulfur  content to present no S02 emission problem,  but
 are  in  short supply and  command  higher prices than the high sulfur fuels. The
_ The No. 2 distillate available to domestic markets has  a sulfur cont
   whTch averages 0.25 percent (by weight)  and ranges from o!01 to 0 7
                                   4-173

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    TABLE 4-17.  EMISSIONS FROM ENGINES BURNING SEWAGE DIGESTOR GAS
                 (from Reference 144)
Engine #
1
2
3a
4*
HP
1100
1100
1600
1600
# cyl
10
10
8
8
rpm
330
330
352
350
Fuel
% CH4
62
60
64
64
Heating
Value
580
557




Emissions, g/hp-hr
N0x
3.14
8.43
2.21
2.37
CO
<0.1
<0.1
<0.1
<0.1
HCT
0.96
0.91
9.16
5.65
S02
0.10
0.12
1.08
1.03
^ual-fuel operation, 4.5 gallon/hr No. 2 diesel; 14,600 scf/hr gas.

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                       TABLE 4-18.  SELECTED APPROXIMATE PROPERTIES OF CRUDE OILS CURRENTLY GENERATING
                                   U.S. RESIDUAL OIL SUPPLY (Reference 147)
en
Origin

Venezuela
Libya
Mid-East
Indonesia
Alaska (North Slope
and adjacent)
California

Vanadium
(ppm)
100-900
7
20-50
—
15-30
100-200
Property
Nickel
(ppm)
30-100
10
5-15
20
5-15
100
Sul fur
(wt %)
1-6
0.3
1-3
0.1
1
1-5
Nitrogen
(wt %)
0.2-0.6
0.15
0.1
0.1
0.2
0.6-0.9
Residual
Percent
(@ 787°F)
30-60
25
30
50
35
60
Residual
Carbon
(wt %)
10-15
8
10
5
10-15
10

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sulfur content of  residual  oil  can  be reduced  by catalytic hydrodesulfuriza-
tion, a petroleum  refining  technique.   Costs for this refining are discussed
in Section 8.2 for different  amounts  of fuel sulfur.
       Residual oils,  blends,  some  crudes,  and heavy  distillate  also contain
higher amounts of  fuel-bound  nitrogen than  the lighter  distillates.
Therefore, the combustion of  these  fuels may result in  greater NOX emissions
than if lighter distillates were burned.  However,  a  byproduct of catalytic
hydrodesulfurizatlon is a reduction 1n  both the metal  and nitrogen content,
as well as the sulfur, of the residual  oils.   Thus, fuel  oil  desulfurlzatlon
processes can reduce fuel nitrogen.  In one case,  using a high sulfur,  high
nitrogen residual  fuel feedstock, 78 and 94 percent sulfur removals  were
accompanied with 40- to 70-percent  reductions  in  nitrogen,  respectively^48).
At this time,  however, there are no known emissions  data for stationary 1C
engines burning heavy fuels.  Thus, the effect of  heavy fuel combustion on
NOX  and other  emissions is unknown.
4.5    EMISSION REDUCTION TECHNIQUES PRIMARILY FOR HC AND CO
       As mentioned in Subsection  4.4.12 hydrocarbon (HC) and carbon monoxide
 (CO) emissions from large-bore  engines  are generally low, especially when the
engines  are operated  at  steady  state.   Therefore,  very little effort has been
expended  by manufacturers to reduce the emission rate of these pollutants,
except where  ancillary to  a  smoke  reduction program.   One foreign
manufacturer  of medium-bore,  high-speed engines has developed a relatively
 low  HC and CO engine  for  use 1n mines  (0.4 and 1.8 g/hp-hr,  respectively,
 based on the  13 mode  composite  test  cycle)(149),  and  at  least one domestic
manufacturer  of catalysts  markets  a  HC and CO catalytic  oxidation unit for
 truck sized  dlesel  and gas-fueled  engines^150).  When  Installed on a diesel,
                                    4-176

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  these catalysts  bring about  reductions of 70 percent in CO emissions and 45
  percent  in HC  emissions while fuel consumption, peak smoke, and NOX emissions
  remain essentially unchangedUSl).  Furthermore, catalytic systans to reduce
  HC  and CO emissions from heavy duty gasoline and diesel have remained 80
  percent  to 95 percent effective for both gasoline and diesel  engines
  throughout the 1000-hour test(152,153).  No  attanpt to  extend e1ther Qf  thfise
  approaches to large-bore engines has  been reported,   Therefore,  the
  description of the HC and CO control  techniques which are  presented  below  are
 mostly qualitative and frequently draw upon  experience  gained with medium-
 bore, medium-to-high speed  engines.
        In general,  the  combustion process  is  enhanced by high  temperatures,
 freely available  oxygen,  good mixing  of the fuel-air  mixture,  and long
 residence times.   Since  these conditions  also result  in the highest NOX
 formation rates,  care must  be exercised in a balanced emission reduction
 effort not to reduce HC  and CO  at the expense of NOX.  Therefore, attempts to
 reduce HC and CO  emissions must  concentrate on quench layer effects,  air-to-
 fuel  mixture  inhomogenelties, fuel droplet size, exhaust gas treatment,  and
 the  like.
        The three major approaches to control  of HC,  (1)  modifying air and
 fuel  handling systems, (2) modifying combustion chamber  designs,  and  (3)
 treating the exhaust, are discussed In detail  in the  following subsections.
4.5.1  Modifications  to A1r  and Fuel Handling  Systans
       This category  of  HC and CO emission  control techniques  can  be  further
divided into  the three subcategorles listed below:
                                  4-177

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       1.   Air-to-fuel  mixture
       2.   Liquid fuel  injection  (compression ignition engines only)
       3.   Cylinder  scavenging
       Since HC and  CO  emissions  decrease  as the  combustible mixture becomes
leaner, at least up  to  a point  (see Figure 4-28),  increasing the air-to-fuel
ratio can  be a control  technique  for  these pollutants.  On a diesel engine
this usually requires  the addition of a turbocharger,  if  the engine is not
already equipped with  one,  or  an  increase  in the  capacity of the existing
turbocharger unit.  In a carbureted spar-k-ignition engine, the air-to-fuel
ratio can  be changed by alterations to the Venturis  and fuel nozzles in the
carburetor.1  Unfortunately,  as  shown  in Figure  4-28,  both minimum HC and
maximum NOX emissions  frequently  occur at  about the same  air-to-fuel ratio.
Hence this approach  has limited utility in a total emission reduction
program, unless coupled with other  controls.
       Some carbureted gas engines,  however,  are  adjusted to operate near
stoichiometric, on the average, to  overcome the problem  of poor  distribution
of fuel and air among the cyl inders(154).   These  same engines  would  have
excessively lean mixtures in some cylinders if  the carburetor  were  not set
rich,  and these lean cylinders could not support  combustion  (i.e.,  they would
exceed the lean misfire  limit).  This problem  can be ameliorated by improved
aerodynamic; design of  the carburetor   and  intake manifold system  or  by
converting the  engine to a fuel injection system.  In fact, most large-bore,
gas  fueled-engines  already use fuel   injectors.
       The [Injector in  a liquid fueled compression ignition  engine is
required  to  deliver fuel only when specified,   to  atomize the  fuel  into
droplets  of'the smallest possible diameter, to distribute these  droplets
uniformly throughout the combustion  volume, and to avoid impinging fuel  on

                                   4-178
                                                       I     /'  *
                                                        \

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 the relatively cool cylinder walls (potential  quench  layer).   Therefore,
 attempts to reduce hydrocarbon (and smoke)  emissions  have traditionally
 concentrated on higher injection pressures  to  improve atomization  and  on
 changes to the design of the injector tip,  in  particular,  hole size,
 location, and number(155).   Frequently these efforts  have  gone hand-in-hand
 with changes to the shape of the piston head,  because wall  impingement
 problems can sometimes be reduced by  directing a  portion of the fuel spray
 onto the contoured surface of the piston  head.
        A major change  to the injector  that  reduces HC emissions is the
 introduction of  the low sac nozzle  (LSN)  injector.  As shown in Figure
 4-55(156),  older  nozzles  use a valve that is located  at some distance from
 the injector tip  to control  the flow of fuel into the  combustion chamber. A
 consequence  of this design  is the presence of  a small  volume,   or sac, within
 the injector that lies  between  the  valve  and the combustion chamber.   When
 the valve  is open,  the  fuel  flows through this sac on  its way to the
 conbustion chamber, where it  mixes  with the air, ignites, and  contributes  to
 a  rapid pressure  rise  in the  cylinder.  The high cylinder pressure prevents
 any fuel that  is  in this  little passageway when the valve closes from
 entering the  cylinder  during the combustion process.   However,  as  the piston
 moves away from the cylinder  head during the expansion process, this  remaining
 fluid "dribbles"  out of the sac.  Since the  cylinder  temperatures  are too
 low  to support con bus ti on by now, these droplets remain un burned,  or  are only
 partially oxidized, and eventually pass into the exhaust  system in  that  form.
       Several manufacturers have practically overcome this  problem by
 switching to a nozzle with a greatly reduced sac volume,  i.e.,  a low  sac
 nozzle(157).   A schematic representation of  such an injector is  shown in Figure
4-55.  In some designs  of sac volume is so small  as to be  virtually negligible.
                                   4-179

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                                              Fuel under pressure
                                          Valve
00
o
                                            -Holes through which fuel  is
                                             atomized into the cylinder
                          a.
Old standard production
spray tip.
b.  Low sac volume spray
    tip.
                           Figure 4-55.  Schematic illustrations of standard production
                                        spray tip and the low sac volume spray tip.
                                        (after Reference 157).

-------
 The use of such nozzles  lead to 30- to 35-percent  reductions  in HC  and C0(158).
 The reductions were  accompanied by a  decrease  in opacity to 4 percent (at
 rated conditions);  NOX emissions,  however,  rose nearly  35 percent,  probably
 as a result  of changes in  the injector tip  design  that  accompanied  the switch
 to a lew sac volune.   These  changes  could alter the fuel spray pattern and/or
 degree of atomization.
        Unburned or  partially burned  hydrocarbons that come from either
 injector "dribble"  or  quench layers  are usually concentrated in the last
 volumes  of gas to  be expelled from  the  cylinder during the exhaust stroke.
 Therefore, EGR,  whether  internal or external, serves to reduce HC emissions,
 in addition  to NOX,  as long  as  the recirculation rate is not so great that
 portions  of  the  combustion reaction are quenched.  Reductions in the
 scavenging pressure  in a two-stroke, blower-scavenged engine can also have
 the same  effect.

 4,5.2  Combustion Chamber Modifications
       When  one  discusses HC  and CO control  techniques for  large-bore
 engines,  one must remember that these contaminants  are present only at  very
 low  quantities  (typically below 2.0 g/hp-hr) in the exhaust  from  these  units.
 This is so mainly because of  the presence  of excess air during combustion.  In
 addition, the  high temperatures and relatively long residence  time  (low  engine
 speed) facilitate the combustion of the fuel.   Finally,  the  large  voline, low
 surface-to-volume ratio,  and  use of injectors  gives the  engineer  of  medium-
 and-large-bore units  more control  on the following  parameters  than  he has with
 automobile-sized engines:   air-to-fuel  distribution within a cylinder,
 variation in air-to-fuel  ratio among cylinders,  and fuel droplet  impingement
on the cylinder walls.  As  a  result,  an average  value for the total  HC
                                   4-181

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emissions from a variety of large engines is 2 g/hp-hr (see Figure 4-52)
which corresponds to 0.1 percent of the incoming fuel.£^/  Thus,  even  though
combustion characteristics are evidently very good from the point of  view  of
HC and CO, combustion chamber design can be important  as  one attempts  to
oxidize the last 0.1 percent  of the fuel.
       A variety of chamber designs has already been  presented  in Section
4.4.8.  Of these techniques,  higher swirl,  inlet valve and/or port  redesigns,
and contoured pistonheads reduce HC and CO  because they improve the mixture
rate and homogeneity of the fuel and air.  The designs for  staged combustion,
such as precombustion chambers and "squish  lips",  can  reduce HC and CO, too.
These geometries cause the combusting mixture to expand the available  oxygen
with the unburned or partially burned fuel.   Unfortunately  this mixing
process is also the source of some increased fuel  consumption;  as the  burning
mixture expands into the main chamber,  its  pressure is decreased  slightly,
resulting in reduced power output.   The mechanical  energy lost  by the  gas
becomes thermal energy and is seen  as a slight increase in  the  gas
temperature.   Of the 5- to 8-percent energy loss attributed to  precombustion
chambers (see Section 4.3.8),  however,  most is probably due to  the  heat loss
in the precombustion chamber.
       Another technique that is available  to decrease HC emissions, especially
from diesel  engines without affecting NOX emissions,  is to  reduce the  "quench
layer",  or region immediately adjacent  to the combustion  chamber  surfaces.
     comon assumption  used  in  calculating mass  emissions  of  total hydro-
     rbons is  that  a typical hydrocarbon tr
   is the  same as  a typical  fuel  molecule'
carbons is  that  a typical  hydrocarbon molecule  emitted in the exhaust
                                   4-182

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  Heat transfer outward through the cylinder walls causes  the mixture
  temperatures in this layer to be too low to support  complete  combustion.(16°)
  Some unburned hydrocarbon emissions  in diesel  engines  result  from fuel
  droplets that were injected into this "quench  layer".  Attempts to reduce
  this source of HC emissions rely primarily on  injector design to avoid
  impinging the fuel  droplets onto the  cylinder  walls  and on relocation of the
  uppermost piston ring as  close to the  piston head as possible to minimize the
 relatively cool  space between the piston  and the cylinder adjoining the
 combustion volume^6*).
        These quench  layer  hydrocarbons  could theoretically be reduced by
 using higher cooling water  temperatures.  However, the increase in wall
 temperatures may give rise  to structural problems (current cooling systems
 are presumably designed to  avoid  such problems) and,  in any case,  the
 resulting higher  combustion temperatures would result in  an increase  in  N0¥
                                                                          A
 emissions.
        Since  high temperatures are conducive to complete  combustion and,
 hence,  low HC and CO  emissions, these pollutants can  be minimized  by  raising
 the  peak  combustion temperature through an increase  in  the compression ratio.
 This  parameter is the ratio of the largest volume in  the  cylinder to  the
 smallest  —  i.e., the ratio of the volume when  the piston  is at the bottom of
 its stroke (bottom dead center or BDC) to that  when  it  is  at the top  (TDC).
 Increasing this ratio increases the volume  change  and hence the temperature
 rise of the fuel  and air during the compression stroke.  This  approach
 also increases the efficiency of  the  engine,  but  unfortunately at the expense
of higher NOX emissions.
                                  4-183

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4.5.3  Exhaust Treatment
       Potential  methods  of  treating the exhaust to reduce NOX emissions
have been discussed in Section  4.4.9.   Here we  are concerned only with
catalytic converters,  thermal reactors,  and exhaust manifold air injectors,
which are designed to reduce HC and CO  emissions.  Although these systems
have been tested on small- and  medium-si zed engines, to our knowledge they
have not been used on large-bore units.  Application of  these techniques to
large engines require careful  design  to insure  that  proper operating
temperatures are maintained in  all  parts  of  the larger  units.  The oxidation
reactions which convert the HC  and CO to water  and  COg  take place only above
a  certain temperature, and this high-temperature environment  1s maintained
inside the exhaust treatment unit by the heat from  earlier reactions.  It 1s
more difficult to  Insure the existence of  a homogeneous high-temperature
environment throughout the  combustion volume of a large unit  than  of  a  small
one because the  heat  release from localized reactions  is absorbed  by  more  gas
In the  large system than  in the small one.  That is,  the heat  generated  may
 not affect  the entire volume in the large unit.  Nevertheless,  there  does  not
seem to  be  any technical  reason why such units  cannot  be designed.
        The  catalytic  converter  has been proven  on mobile gasoline engines  and
functions  by  causing  the  oxidation reaction to continue at reduced
 temperatures.   It is  a passive  device which consists of a container that
 houses  a porous  structure covered  with the catalyst material.  The converter
 replaces a portion of the exhaust  tail pipe.   The chemical reaction then
 takes  place on the catalyst-coated surface as  the exhaust passes through the
 converter.   If automotive type platinum catalytic converters are used,  only
 unleaded fuels  can be burned to avoid  inactivating the catalyst.  In
 addition,  fuels with low sulfur content should be used to suppress sulfurlc
                                    4-184

-------
 acid formation (HgSC^).  This  technique is not limited to small-bore engines
 and  could,  therefore,  be applied to large-bore units as well.  The need to
 design  the  converter to operate at uniform elevated temperature has already
 been  discussed;  cost implications are considered in detail  in Section  8.2.
        In the  thermal  reactor  air is added to the exhaust stream in a
 container which  is located in the exhaust pipe system and is specially
 designed to maximize both the residence time of the charge  and its
 turbulence.  The purpose of the device is to provide a site where oxidation
 can  proceed at elevated temperatures.   These are maintained by the  heat
 released from the oxidation reaction of CO and HC with excess  air.  Air
 injection into the exhaust manifold functions to the same end  as  the thermal
 reactor.  However, it is not as effective  an oxidizer  of  HC  and CO  as  the
 thermal reactor because it utilizes  the  existing  shape  of the  exhaust  systen.
 This volume is generally not optimized for maximum  residence time,  heat
 retention,   or turbulent mixing.
 4.6    SMOKE
       In general smoke in well  operated and  maintained large-bore  engines  is
a problem only for  compression  ignited engines when  fired with  nothing  but
 liquid fuel.  Attempts  to  reduce visible emissions  aim  at reducing  locally
 rich  zones  by improving air-to-fuel mixing and distribution throughout  the
cylinder.  The  following techniques are most  commonly used for this purpose:
       t  Improved combustion  through chamber redesign, particularly piston
          head shape and increased swirl
       t  Leaner air-to-fuel ratio (by carburetor adjustments, inlet
          manifold design, or turbocharglng)
                                  4-185

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       •   Improved fuel  atomization  and  dispersion
       •   Low-sac volume injectors
A number of manufacturers have  successfully reduced smoke emissions over the
operating range of large  diesel  engines through the use of improved needle
and low-sac fuel injector designs.  Visible emissions from most current,
properly maintained units are well  below  10-percent opacity during continuous
load application^62*163).
       Figures 4-56(164)  and 4-5?(165)  illustrate the improvements obtained
by the Electromotive Division (EMD) of  General Motors on  both  blower-
scavenged and turbocharged versions  of  their  two-stroke Model  645  diesel
engine  (although this engine is used  mainly in  locomotives,  it is  also sold
for stationary applications).  Smoke  reductions were  also achieved on these
engines by widening the size of the ports in  the  cylinder liners 12-1/2
percent to improve charging and scavenging processes  and  by moving the top
piston ring  ("fire ring") three-quarters  of  an  inch higher.  Sea level  smoke
emissions at rated conditions are now about 6-percent opacity  for  both
engines,  having been reduced from 20 percent  for  the  turbocharged  unit  and
30 percent for the blower scavenged one.   The effect  of  derating is shown in
Figure  4-56  to  illustrate that this technique has  to  be  used with  blower-
scavenged engines  at high altitude in order to  comply with  local regulations
that  restrict  visible emissions to a Ringelmann No.  1 (20-percent  opacity).
        Although not recommended by manufacturers,  additives  are  sometimes
mixed with the  fuel to reduce smoke.   Barium  is a common additive  and
                                   4-186

-------An error occurred while trying to OCR this image.

-------An error occurred while trying to OCR this image.

-------
 reportedly reduces the particulate mass  emission ratej£/  in medium-bore
 dies el  engines by as much as  50  per cent (166~168).  This is theorized to be
 due to the inhibiting effect  of  the  barium  on the formation of carbon in the
 vicinity of the burning fuel  droplets,  or to its action as a catalyst
 accelerating the oxidation  of  the  carbon formed(169).
        In  addition to reportedly decreasing the mass of particulate emitted,
 the character of the particulate composition is altered as well by the
 additives^7^).  jnjs was observed in one case where carbon comprised
 96  percent, hydrogen 2 percent,  iron 1  percent, and zinc  1 percent of the
 particulate sampled when  untreated fuel was used.  In contrast, carbon
 comprised  only 36 percent and  hydrogen  1 percent of the particulate mass
 emitted when  a barium treated  fuel was substituted.  Barium sulfate (83804)
 now represented about 60 percent of  this mass, and iron and zinc were present
 in  trace quantities  only.
        Despite the  effectiveness of  this approach, it is  not favored by
 industry because of  concern over possible build-up problems that might occur
 at  the  cylinder  ports  as  a result  of the increased metallic content of the
 fuel(171>172K   Furthermore, BaS04 and tne other soluble barium compounds
 produced may  represent  a health  hazard when emitted into the atmosphere in
 substantial quantities.
        Although  no  particulate scrubber is known to have been  used on large-
 bore engines,  probably  because they usually operate at steady  state and
 generally emit  little smoke, one automobile-oriented service industry has
 developed such a  device to remove lead  particulates from automobile
12/
	 The level of smoke opacity was determined using a Hartridge  Smokemeter.
   The weight of solid particulates was measured by filtering a precise
   volume of exhaust gas through glass filter papers and weighing the
   deposited soot.
                                   4-189

-------
exhaust(173).   In tests  on four  cars  equipped with these  particulate traps
the average air-suspended lead emissions were reduced about 67 percent from
26.6 to 10.1 percent of  the lead contained in the fuel.   The same  particulate
trap also reduced total  particulate emissions  (one-fifth  of which  is lead) by
74 percent.
       Presumably, a similar system,  or one of  the many  kinds  of  particulate
scrubbers  available, could be used if it were  decided  to  reduce NOX
significantly by means of large amounts of retard or EGR.  Both these
techniques  reduce NOX effectively, but, beyond a certain point,  only at  the
expense of  smoke.
                                    4-190

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                            REFERENCES  FOR  SECTION  4
  (1)  Lachape  le,  D. G,,  J.  S.  Bowen,  and R.  P.  Stern  (EPA).  Overview of
  Environmental Protection Agency's NOX Control Technology  for Stationary
  Combustion Sources.   (Presented at 67th AICHE Annual  Meeting.   December 4
 1974).
  (2)  Durkee, K., E. A. Noble, F. Collins, and D. Marsland  (EPA).  Draft
  Standards Support Document:  An Investigation of the Best  Systems of  Emission
 Reduction for Stationary Gas Turbines.  Environmental Protection Agency
 August 1974.  p. VI-17.

 (3)  Ibid.

 (4)  Ibid.
 (5)  Urban, C. M., et al.  Emissions Control Technology Assessment of Heavy
 Duty Vehicle Engines.  EPA-460/3-74-007.  December 1973.

 HL ^]emin9>uD<  R'na!?d I: R-,Frencn-  Durability of Advanced Emission
 Controls for Heavy Duty Diesel and Gasoline Fueled Engines.  EPA-460/3-73-010
 September 1973.
 cA R: B;.and A-  J-  Rogowski.   The Interaction of Air Motion, Fuel
 Spray,  and Combustion in the  Diesel  Combustion Process.  Journal of
 Engineering for Power.  94,  Serial A,  No.  1.   January 1972.


 (81  T!!aJterS0?' ?'  J; and  ?•  A>  Hene1n-   Emissions From Combustion Engines
 and  Their  Control.   Ann Arbor,  Michigan.   Ann Arbor Science Publishers, Inc.,
 iy '" •   . bcl) .
 (9)   Savery,  C.  W., R. A.  Matula,  and  T.  Asmus.   Progress  in Diesel  Odor
 Research.   SAE  Paper  740213.   February 1974.                "uiweiuaor

 (10)  Springer   K. J. and  C.  T.  Hare.   Four  Years  of  Diesel  Odor  and Smoke
 control Technology Evaluations  —  A  Summary.  ASME Paper 69-WA/APC-3
 November 1969.

 (11)  Springer,  K. J. and R.  C.  Stahman.  Control  of  Diesel  Exhaust  Odors

                                                 '        NeW Y°rk' New Y°;k
              c         ?f,0dor Components in Diesel Exhaust.  Arthur D. Little.
              September 1973.
(13)  Springer and Stahman, Op. Cit.

(14)  Patterson,  D.  J., Op. Cit.. p. 132.

(15)  Ibid.,  pp.  32,  267.
      ^"™~^^^~~

(16)  Ibid.,  pp.  219, 286.
                                      4-191

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(17)  Ibid., p. 272.
(18)  Roessler, W. U., A.  Muraszew, and R. D. Kopa.  Assessment of the.
Applicability of Automotive Emission Control Technology to Stationary Engines.
EPA-650/2-74-051.  July 1974.
(19)  Turley, C. D., D. L. Brenchley, and R. R. Landolt.  Barium Additives
as Diesel Smoke Suppressants.  Journal of the A1r Pollution Control Association.
23_.  September 1973.
(20)  Bolt, J. A. and N. A. Henein, The Effect of Some Fuel and Engine Factors
on Diesel Smoke.  SAE Paper 690557.  August 1969.
(21)  Patterson, D.  J., Op_. C it., p. 272.
(22)  Ibid.
(23)  Offen, G. R.  (Acurex/Aerotherm).  Trip Report.  November 26, 1974.
(24)  Standards of  Performance for Fossil-Fuel Fired Steam Generators.  Federal
Register.   36  (247), Title 40, Subpart D.  December 23, 1971.
(25)  Jenkins, R. and G. D. McCutchen.  New Source Performance Standards.
Environmental  Science  and Technology, j5.  October 1972.
(26)  Standard Practices for Stationary Diesel and Gas Engines, Diesel Engine
Manufacturers  Association,  p. 118.  Sixth Edition.  1972.
(27)  S. R.  Krause, D.  F. Merrion,  and G. L. Green, "Effect of Inlet Air Humidity
and Temperature  on  Diesel  Exhaust  Emissions,"  SAE Paper 730213.
(28)  Coordinating  Research Council  (CRC),  "Effect of Humidity of Air  Intake
on  Nitric  Oxide  Formation  in Diesel  Exhaust,"  CRC Report  447, December 1971.
(29)  "Revised Heavy  Duty  Engine Regulations for 1979 and Later Model  Years,"
Federal  Register, Volume 41, No. 101, May 24,  1976.
(30)  Environmental Protection Agency (40 CFR  Part 85, Subpart A), "Control
of  Air  Pollution  from New Motor Vehicles and New Motor Vehicle Engine,"
(Notice of Proposed Rule Making),  February  1971.
(31)  Krause,  Merrion,  and Green,  Op. Cit.
(32)  S. R.  Krause, "Effect  of  Engine  Intake-Air Humidity, Temperature,  and
Pressure on Exhaust Emissions,"  SAE Paper 710835.
(33)  Private  communication  between C.  L. Newton  (Colt)  and D. R.  Goodwin,
August  2,  1976.
 (34)  Krause,  Op. Cit.
 (35)  W. J. Brown,  et al.,  "Effect of Engine Intake-Air  Moisture  on  Exhaust
Emissions," SAE Paper 700107.
                                       4-192

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 (36)   Scott Research Laboratories,  "Effect of Laboratory Ambient Conditions
 on  Exhaust Emissions,"  Project No.  2846.
 (37)   J. A. Robinson,  "Humidity Effects on Engine Nitric Oxide Emissions  at
 Steady-State Conditions,"  SAE Paper  700467.
 (38)   Coordinating Research Council  (CRC), "Effect of Humidity of Air  Intake
 on  Nitric Oxide Formation  in Diesel  Exhaust," CRC Report 447, December 1971.
 (39)   Reference 29, Op. Cit.
 (40)   Krause, Merrion, and Green, Op. Cit.
 (41)   Private Communication between  R. W. Sheppard (Ingersoll-Rand) and
 D.  R.  Goodwin (EPA), June  17, 1976.
 (42)   Krause, Op. Cit.
 (43)   Private communication between  R. W. Sheppard (Ingersoll-Rand) and
 D.  R.  Goodwin (EPA), June  17, 1976.
 (44)   Krause, Op_. Cit.
 (45)   Ibid.
 (46)   Krause, Merrion, and Green, Op. Cit.
 (47)   Krause, Op. Cit.
 (48)   Brown, Op. Cit.
 (49)  Reference 36, Op. Cit.
 (50)  Private communication between C. K.  Powell (Ingersoll-Rand)  and G. R.
Offen  (Acurex/Aerotherm)  August 30,  1974
 (51)  Urban, C.  M. and K.  J. Springer, Study of Exhaust Emissions from Natural
Gas Pipeline Compressor Engines.   Southwest Research Institute.   PR-15-61
February 1975.
 (52)  Krause, Merrion, and Green,  Op. Cit.
(53)  Reference  28, Op. Cit.
(54)  Krause, Merrion, and Green,  Op. Cit.
(55)  Reference  28, Op. Cit.
(56)  Krause,  Merrion,  and Green,  Op. Cit.
(57)  Ibid.
(58)  Brown,  Op.  Cit.
                                      4-193

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(59)  Urban and Springer, Op.  C1t.

(60)  Coordinating Research Council (CRC)  "Cooperative Study of Heavy Duty
Diesel Emission Measurement Methods," CRC  Report 487, July 1976.

(61)  Coordinating Research Council (CRC)   "Cooperative Study of Heavy Duty
Diesel Emission Measurement Methods," CRC  Report 487, July 1976.

(62)  Recomnended Practice for Heavy Duty  Engine Emission Measurement and
Test Procedures.  EPA/Office of Air and Waste Management/Emission Control
Technology Division/Standards  Development  and Support Branch.  February 28,
1977.

(63)  Diesel Exhaust Emission  Measurement  Procedure for Low and Medium Speed
Internal Combustion Engines.  Diesel Engine Manufacturers Association.  1974.

(64)  Measurement of Carbon Monoxide, and  Oxides of Nitrogen in Diesel
Exhaust — SAE J177A.  Society of Automotive Engineers.  March 1974.

(65)  Private conmunication between T. M.  Fisher (6MC) and D. R. Goodwin (EPA)
May 12, 1976.

(66)  Holman, J. P. Experimental Methods for Engineers.  McGraw Hill,
New York, N.Y.  1971.

(67)  Juneja, W. K., D. D. Horchler, and H. M. Haskew.  "A Treatice on Exhaust
Emission Test Variability," SAE Paper 770136, 1977.

(68)  Youngblood, S. B. (Acurex/Aerotherm).  Meeting report.  April 22, 1975.

(69)  Ibid.

(70)  Private conmunication between C. L.  Newton (Colt) and D. R. Goodwin
(EPA), August 2, 1976.

(71)  Private communication between C. L.  Newton (Colt) and D. R. Goodwin
(EPA), April 2, 1976.

(72)  Private conmunication between G. P.  Hanley (GMC) and D. R. Goodwin (EPA),
January 29,  1975.

(73)  Ibid.

(74)  Standard  Practices  for Low and Medium Speed  Stationary Diesel and Gas
Engines.  Diesel Engine Manufacturers Association.   New York, New York.  1972.
p.  28.

(75)  Schaub, F. S.  and K.  V. Beightol (Cooper-Bessemer).  Effect of  Operating
Conditions  on Exhaust  Gas  Emissions  of Diesel, Gas  Diesel, and  Spark  Ignited
Stationary  Engines.  Unpublished Cooper-Bessemer Co. Report.  Presented  at
the Gas Compression  Shortcourse, Norman,  Oklahoma,  Fall  1973.

(76)  Patterson  and  Henein, Op_. Cit.,  pp.  267-268.


                                       4-194

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 (77)   Roessler,  Muraszew,  and  Kopa,  Op_.  C1t.,  p.  5-3.
 (78)   Fletcher,  J.  S.  (Acurex/Aerotherm)  Meeting  report.   April 22,  1975,
 (79)   Offen,  6.  R.  (Acurex/Aerotherm)  and F.  S.  Schaub  (Cooper-Bessemer).
 Private  cormiunication.   October 13,  1975.
 (80)   Youngblood,  S.  B.  (Acurex/Aerotherm)  and M.  P.  Thompson (White Superior).
 Private  conmuni cation.   February 20,  1976.
 (81)   Ewing,  6.  H.  (AGA)  and D.  R. Goodwin  (EPA).   Private communication,
 September  24,  1976.
 (82)   Patterson  and Henein, Op.  Cit.,  pp. 125, 267.
 (83)   Reference  78, Op.  Cit.
 (84)   Ibid.
 (85)   Patterson  and Henein, Op.  Cit.,  pp. 206-207.
 (86)   Cox, N.  S. (Waukesha) and  G. R.  Offen (Acurex).   Private  communication.
 June  16, 1975.
 (87)   Schaub  and Beightol, Op.  Cit.
 (88)   Reference  68, Op.  Cit.
 (89)   Ibid.
 (90)   Patterson  and Henein, Op_.  Cit..  pp. 125,  267.
 (91)   Obert, E.  F., Internal Combustion Engines and Air Pollution.   Intext
 Educational Publishers.  New York, New York.   1973.  p. 619.
 (92)   Reference  68, Op. Cit.
 (93)   Youngblood, S. B.  (Acurex/Aerotherm) and J. Webb  (Turbos, Inc.).  Private
 communication.   June 5, 1975.
 (94)   Roessler, Muraszew, and Kopa, Op. Cit.   pp. 4-82, 4-84.
 (95)   Storment,  J.  0.  and K. J.  Springer.  Assessment of Control Techniques
for Reducing Emissions from Locomotive Engines.  Southwest Research  Institute.
AR-884.  April 1973.
 (96)  Roessler, Muraszew, and Kopa, Op_. C1t.
(97)  Shaw, J. C.  Emission Reduction Study on a Carbureted Natural Gas Fueled
Industrial  Engine.   Draft ASME Paper.  White Superior Division.  White Motor
Corporation.   November 1974.
                                       4-195

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(98)  Schaub, F.  S.  (Cooper-Bessmer).   Methods of Reduction of NO  Emissions
from Large Slow Speed Diesel  Engines.   U.S.  Army Corps of Engineers.   DACA
87-70-C-0019.  June  24,  1970.  pp.  12

(99)  Fleming and French, Op_.  Cit.

(100)  Ibid.

(101)  Characterization and Control of Emissions From Heavy Duty Diesel and
Gasoline Fueled Engines.  Fuels Combustion Research Group.  Bartlesville Energy
Research Center, Bureau of Mines.   EPA-IAG-0219(D).  December 1972.  NTIS:PB219052

(102)  Bosecker, R.  E. and D.  F. Webster.  Precombustion Chamber Diesel
Emissions -- A Progress Report.  SAE Paper No. 710672.  August 1971.

(103)  Urban, Op. Cit.

(104)  Fleming and French, Op. Cit.

(105)  Youngblood, S. B.  (Acurex/Aerotherm) and G. Hanley  (General Motors).
Private  communication.  May 19, 1975.

(106)  Bosecker  and Webster,  Op. Cit.

(107)  Shaw, 0£. Cit.

(108)  Bosecker  and Webster,  Op. Cit.

 (109)  Ibid.

(110)  Offen,  G. R.  (Acurex/Aerotherm)  and  F.  Schaub  (Cooper-Bessemer).   Private
comnunication.   January  13-14,  1975.

 (Ill)  Shaw, Op. Cit.

 (112)   Storment  and  Springer, 0£.  Cit.

 (113)   Shaw, Op. Cit.

 (114)   Walder, C.  J.   Can Diesels Meet 1975 California Emission Limits?  Auto-
motive Engineering.   80:27-30.   December 1972.

 (115)   Bascunana,  J.  L.   Divided  Combustion Chamber  Gasoline Engines:  A Review
 for Emissions and  Efficiency.  Journal of the Air Pollution Control Association.
 20 (7).   July 1974.

 (116)   Urlaub, Alfred.  How M. A. N.  Cleans Up Diesel Engine Exhaust.
 M. A.  N. Research  Engineering.  Manufacturing.  No.  4.  October 1973.

 (117)   Bertodo, R., et al.   Evolution of a New Combustion System for Diesel
 Emission Control.   Perkins Engines Company (England).  SAE 741131.  November
 1974.
                                        4-196

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 (118)  Walder, Op_. C1t.

 (119)  Bosecker and Webster, Op_. C1t.

 (120)  Diesel and Gas Turbine Worldwide Catalog.   Diesel  and Gas  Turbine  Progress.
 Milwaukee, Wisconsin.  39.  1974.

 (121)  An Automotive Engine That May be Cleaner.   Environmental Science and
 Technology.  ]_.  August 1973.  p.  688.

 (122)  Johnson, P. R., et  al. (GMC).  Vehicle  Emission  Systems Utilizing  a
 Stratified Charge Engine.  SAE Paper 741157.   October 1974.

 (123)  Bertodo, Op_. Cit.

 (124)  Ibid.

 (125)  Ibid.

 (126)  Durkee, K. R. (EPA/ISB) to J. C. Berry  (EPA/Chief  ISB).  Meeting report
 with DEMA representatives, September 3, 1974.

 (127)  Hartwell, N. J. E.  (Perkins Engines, Farmington, Michigan).   Letter
 to G. R. Offen (Acurex/Aerotherm).  November 18,  1974.

 (128)  Brisson, B., et al.  A New Diesel Combustion Chamber -- The Variable
 Throat Chamber.  SAE Paper 730167.  1973.

 (129)  Henderson, R. D. (Caterpillar Tractor Company).  Commentary on  Diesel
 Exhaust Emission Control System.   November 11, 1974.

 (130)  Mooney, J. J., C. E. Thompson, and J. C. Dettling  (Engelhard) "Three-
 Way Conversion Catalysts:  Part of the New Emission Control System," SAE  Paper
 770365.  1977.

 (131)  Bradow, R. L., F. D. Stump, (EPA) "Unregulated Emissions from Three-
 Way Catalyst Cars," SAE Paper 770369.  1977.

 (132)  Anderson, H. C., et al. (Engelhard Industries).  Catalytic Treatment
 of Nitric Acid Plant Tail Gas.  Industrial & Engineering  Chemistry.  53.
 March 1961.  pp.  199-204.                                           ~

 (133)  Gillespie, G. R., et al. (Engelhard Industries).   Nitric Acid:   Catalytic
 Purification of Tail Gas.  Chemical Engineering Processes.  68:72-77.
 April 1972.

 (134)  Offen, G.  R. (Acurex/Aerotherm) and A.  W.  Tamarelli (Engelhard  Industries).
 Private communication.  December 3, 1974.

 (135)  Sudar, S.  and Grantham.  Diesel Exhaust Emission Control Program.
Atomics International Division.  Rockwell International.  Report No.  Al-73-61.
 January 1974.
                                       4-197

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(136)  Urban, C. M. and K. J. Springer.  Study of Exhaust Emissions from
Natural Gas Pipeline Compressor Engines.  Southwest Research Institute.  AGA
Project PR-15-61.  February 1975.  p. 57.
(137)  Durkee, K. R. (EPA) Meeting Report, September 3, 1974.
(138)  Newton, C. L. (Colt Industries).  Letter to G. R. Offen (Acurex/Aerotherm)
November 20, 1974.
(139)  Henderson, R. D. (Caterpillar).  Letter to R. D. Selffert (EPA).
January 17, 1975.
(140)  40 CFR 85, Subpart J -- Engine Exhaust Gaseous Emission Regulations
for New Diesel Heavy Duty Engines.
(141)  New Vehicle Standards Summary.  California Air Resources Board Fact
Sheet 6 (Revised).  July 8, 1974.
(142)  Storment and Springer, Op. C1t.
(143)  Sacramento Area Consultants, Study of Methane Uses, Sacramento Regional
       County Sanitation District, June 1976.
(144)  Private coirniunication between G. Thomas (Los Angeles County APCD) and
J. S. Fletcher (Acurex/Aerotherm) December 2, 1974.
(145)  Ibid.
(146)  Madman, B., "Most Efficient Fossil Fuel Generating Plant?"  Diesel
and Gas Turbine Progress.  April 1976.  p. 13-16.
(147)  Whlsman, M. L.  and F. G. Cotton.  BuMines Data Promise Help 1n Identifying
Petroleum Spill Sources.  Oil and Gas Journal.  December 27, 1971.  pp. 111-113.
(148)  Durkee, Op. Cit., p. II-5.
(149)  Diesel and Gas Turbine Worldwide Catalog.  1975 Edition,  p. 10.
(150)  Hansel, J. G. (Engelhard Industries).  Letter to G. R. Offen (Acurex/
Aerotherm).  April 14, 1975.
(151)  Reference 101, Op_. Cit.
(152)  Urban, Op_. Cit.
(153)  Fleming and French, Op. Cit.
(154)  Shaw, J. (White Superior).  Letter to J. S. Fletcher (Acurex/Aerotherm).
November 14, 1974.
(155)  Melton and Rogowski, pj>. Cit.
                                       4-198

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 (156)  A Progress Report on Electro-Motive's Emissions Reduction Program
 for Diesel Engines,  Electro-Motive Division, GMC.  September 1972.
 (157)  Ibid.
 (158)  Storment and Springer, Op_. CJt.
 (159)  Standard Practices for Low and Medium Speed Stationary Diesel and Gas
 Engines.  Diesel Engine Manufacturers Association.  New York, New York.  1972.
 p.  298.
 (160)  Patterson and Heneln, Op_.  C 1t.. pp. 117-124.
 (161)  Bascom,  R.  C.,  et al.  Design Factors that Effect Diesel  Emission.
 SAE Paper 710484.   July 1971.
 (162)  A Progress  Report on Electro-Motive's Emissions Reduction Program
 for Diesel  Engines.   Electro-Motive Division, GMC.  September 1972.
 (163)  Offen,  G.  R.  (Acurex/Aerotherm).   Trip Report.   September 13, 1974.
 (164)  Reference 162,  Op_.  Clt.
 (165)  Ibid.
 (166)  Turley,  Brenchley,  and Landolt, Op_.  C1t.
 (167)  Shamah,  E.  and  T.  0.  Wagner.   Fuel  Quality or Engine  Design:  Which
 Controls  Diesel  Emission?   SAE  Paper No.  730168.   January 1973.
 (168) Golotham, D.  W.   Diesel  Engine  Exhaust Smoke:   The Influence of  Fuel
 Properties  and  the  Effects  of Using  Barium-Containing  Fuel Additive.   SAE
 670092.   1967.
 (169)   Ibid.
 (170)  Shamah and Wagner, Op_. C1t.
 (171)  Ibid.
 (172)  Golotham, Op_. C1t.
 (173)  Adams, W. E., F. J. Marsse, and D. L.  Lenane.   "Lead-Compatible  Emission
Controls — A Route to Improved Fuel Economy."  (Ethyl Corp.)  NPRA Paper
F&L-74-60.  (Presented at Fuels and Lubrication Meeting, National Petroleum
Refiners Association, November 1974.)
                                       4-199

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                                 CHAPTER 5
                     MODIFICATIONS AND RECONSTRUCTIONS

5.1    BACKGROUND
       This chapter identifies and discusses possible or typical changes to
stationary reciprocating internal combustion engines which could be termed
modifications or reconstructions.  According to Federal Regulations, such
changes would subject an engine to a standard of performance.  A modification
is defined as "...any physical change in, or change in the method of
operation of an existing facility which increases the amount of any air
pollutant (to which a standard applies) emitted into the atmosphere by that
facility or which results in the emission of any air pollutant (to which a
standard applies) into the atmosphere not previously em1tted"U).  An
"existing facility" is defined as one which would be required to conform to
a standard of performance, if it were new, but which was, in fact,
constructed or modified before the date of proposal of the standard of
performance.
       The regulation requires the owner or operator of any engine classified
as an "existing facility" to notify the EPA of changes which could cause an
increase in emissions of an air pollutant for which a standard of performance
applies(2).  These changes would not be termed "modifications" — i.e., the
existing facility would not have to meet the standards of performance -- if
                                   5-1

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 the  owner  or  operator  could  demonstrate  that  no  Increase in emissions for
 which  a  standard  applied  resulted  from the  alteration.
        In  addition,  the  regulation also  defines  the term "reconstruction,"
 namely the  ",.,replacement of  a  substantial majority of  the existing
 facility's  components  Irrespective of any change of emission rate"(3).
 Therefore,  1f substantial numbers  of parts  are changed  1n  an engine which
 belongs  to  the class of existing facilities,  this  engine will  be considered
 to have  undergone a  reconstruction and will have to conform to standards  of
 performance as 1f 1t were a  new  engine.  The  purpose of  this provision  is to
 discourage the perpetuation  of a facility which,  in the  absence  of  a
 standard, would normally have  been  replaced(4).  Again,  the regulation
 requires the owner or operator to  provide Information concerning the
 construction or reconstruction of  an existing facility to  EPA(5),
       Certain practices, however,  are exempted  from being  considered as  a
modif1cation(6).   These exemptions  are listed below,  in  terms  that  are
 appropriate for stationary engines.
       1.  Routine maintenance, repair, and replacement  of  parts
       2.  Increases in power generation, provided  such  increases do not
           exceed the rated  power of the engine
       3.  Increases in hours of operation
       4.  Use of an alternative fuel,  if specified  by the  manufacturer for
           that particular engine
       5.  Addition  of a control device which reduces emissions  or
           replacement of a  control device by another of at  least equal
           efficiency
       6.  Relocation or a change in ownership of an engine
                                   5-2

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       The  addition of  a  new, modified,  or  reconstructed  unit  to  a multiple-
unit  installation subjects  only  the  addition  to  a  standard  of  performance and
not the remainder of the  existing  facility(7).
       Specific changes to  stationary, reciprocating  internal  combustion
engines that could be classified as  modifications  or  reconstructions  will be
discussed separately in the following  two sections.

5.2    MODIFICATIONS
5.2.1  General
       As discussed in  Section 5.1,  the  law regarding modifications to
stationary  reciprocating  engines is  very explicit; that is,  any physical  or
operational changes to  an engine that  result  in  increased emissions (for
which a standard applies) subjects that  engine to  a standard of performance.
This  section will discuss those  physical and  operational  changes  to
stationary  engines that could result in  increased  emissions.   Alterations
which are likely candidates to be  exempted  as modifications  are noted.
Physical changes are alterations to  either the engine's structure,  its
components, or its auxiliaries,  and  operational  changes include variations  of
such parameters as fuel,  air-to-fuel ratio, ignition or fuel injection  timing,
and manifold inlet air temperature.
5.2.2  Physical Changes
       In general, stationary engines  are "customized" for  a particular
application, and major changes are not made to their hardware  and  components
during their lifetime other than routine replacement of wearing parts(S-ll).
Practically, then, modifications will usually occur only when  a replacement
part has been altered from the original design,  and the use of this part
causes the engine to produce greater emissions than the original
                                   5-3

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configuration.  Manufacturers have, in fact, made changes  in recent years,
primarily to improve fuel economy and smoke characteristics of their
engines(12,13).  For example, one manufacturer of medium-bore diesel-fueled
engines has made four injector design changes since 1962(14).  Although many
of these changes may reduce HC, CO, or smoke levels, they  frequently will
increase NOx levels.  Hence, if a user replaces an old part with a newer,
modified one, he may be making a change that is a "modification" as defined
by Federal Regulations.  Examples of such changes are discussed in the
following paragraphs.
       The design of various engine components can significantly affect
emissions from an engine.  For example, the cylinder head  shape, the
compression ratio, or the shape of the piston may be altered to enhance
combustion(15).  Since improved combustion frequently results in higher
temperatures within the cylinder, these design changes can cause NOx
emissions to increase.  Another alteration is to move the  uppermost piston
ring to a higher location on the piston.   This change reduces the quench
layer, and hence hydrocarbon formation, but generally does not affect
emissions of the other pollutants.  One study, however, indicated that moving
the uppermost piston ring higher on the piston and increasing the injector
rack setting substantially reduced CO in addition to decreasing HC and caused
the NOX level to increase(16).
       Engine components used for the intake of fuel and air or the exhaust
of combustion products may also influence emissions.  The  number and size of
the holes in a fuel injector as well as the sac volume (see Figure 4-55) have
an effect on emissions(17).   If the fuel injector change improves the
combustion characteristics,  NOx emissions may increase.  Decreasing the sac
volume, in general, reduces  HC emissions without affecting the other
                                   5-4

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 pollutants.   Fuel  pump  characteristics  and  intake  valve  camshaft design
 determine  injection  rates, which  in  turn  affect  combustion  characteristics
 and, hence, emission  rates  (see the  discussions  on  injection  timing and
 internal EGR  in Chapter 4).
        In  spark-ignition  engines  the  carburetor,  intake  manifold,  and intake
 valves  (location and  number)  affect  the mixing of  fuel with air  (both local
 and overall air-to-fuel ratio, see Sections  3.2.1  and  4.1 through  4.4).
 Consequently, changes to  these systems may  increase  the  emissions  from the
 engine, particularly  NOX.  The location,  size, and  number of  ports in the
 liners  of  a two-cycle engine  influence the  amount  of air in the  cylinder  and
 its manner of mixing  with the fuel(18).   Similarly,  blowers,  turbochargers,
 and aftercoolers determine the delivery rate  and temperature  of  the inlet air
 or the  air and fuel mixture (see  Sections 3.2.1  and  4.1  through  4.4).
        The number  and location of exhaust valves also  affect  emissions.   For
 example, a manufacturer of two-cycle  engines  uses heads  with  four  exhaust
 valves  on  engines  that must meet  EPA  or California heavy-duty vehicle
 emission standards, but retains the original  two-valve design for  the
 uncontrolled stationary counterparts  of these truck engines(19).   Variations
 in valve overlap (four-cycle) or  port overlap (two-cycle) can alter  the
 emission characteristics of an engine, too.   The amount  of  overlap  affects
 the amount of oxygen available for combustion as well  as the  temperature  of
 the air or the air and fuel  mixture.   Most of these items could  be  changed by
the user on an existing engine and,  therefore, might be  a modification  in the
present context.
       Large and medium-large engines (>500 hp)  that are intended  for
 stationary applications are occasionally sold without much  of the  auxiliary
equipment,  such  as  radiators,  turbochargers,  aftercoolers,   etc.  Therefore,
                                   5-5

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  if the purchaser does  not  use  a  correctly-sized  cooling  system  (radiator or
  cooling tower), or an  undersized aftercooler  on  a turbocharged  unit,  the
  engine could run hotter than specified by the manufacturer.   In  either  case,
  the temperature of the mixture in the cylinder would be  higher than specified
  by the manufacturer, and hence the NOX emissions would also be higher.   In
  other words, the use of auxiliary equipment that causes  peak  cylinder or
  inlet manifold air temperatures to be higher than specified by the
 manufacturer could be considered a modification.
        Facilities  with many engines usually have a staff of engineers and
 technicians that are  skilled in the operation and maintenance of their
 engines.   These users may  occasionally change portions of an engine to
 eliminate  problems  with the engine  or to  improve  its performance.  Presumably
 these  alterations  involve  only  peripheral  equipment  such  as radiators,
 lubricating oil  feed  systems, etc.,  and hence have,  at most,  a secondary
 effect  on  emissions.   One  user,  for example,  was  able to  reduce  visible
 emissions  from  large,  two-stroke  natural gas-fueled  engines by changing  the
 lubricating oil  feed  system(20).   it  is unlikely,  however,  that  these  users
 would redesign  such emission sensitive components  as  the  fuel  injector,
 intake valve or  port  geometry,  piston head shape,  cylinder  head  shape,  etc.
 5.2.3  Operating Changes
       As  discussed in  Sections 3.2.2.3 and 4.1 through 4.4, emissions from
 an engine  depend, in  part,   on its operating conditions.   Some  of  these changes
 are a consequence of  the normal operation of an engine over the range  of
 conditions for which  it was designed.  For example, variations in torque,
 speed, output power, or air-to-fuel ratio that are within the  engine
specifications belong in this category of  changes.  In contrast,  injection or
                                   5-6

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 Ignition retard or advance from the manufacturer's  specification  or
 purposeful alteration of the air-to-fuel ratio  do not follow from typical
 usage patterns and, therefore, could be considered  modifications.
       The use of fuels not specified by the manufacturer for  a particular
 engine could also constitute a modification,  Such  a condition would  arise,
 for example, 1f an owner or operator began to fuel  an existing engine,  which
 1s specified to burn only No. 2 dlesel oil, with No. 6 o1l.l/  In general,
 though, manufacturers specify a range of fuels  to be used 1n their engines.
 In fact, precombustlon chamber engines are specifically  designed  to
 accommodate a variety of light fuels and dual-fuel  engines  are designed to
 operate In either of two modes:  full diesel or dual-fuel operation.
 Therefore, although fuel type and quality can effect emissions (Section
 3.2.2.3.4), the use of alternative fuels would  constitute a modification only
 if the change were to a fuel not originally intended for use in the engine
 when it was manufactured.

 5.3    RECONSTRUCTION
       A reconstructed engine, as discussed at  the  beginning of the chapter,
 is essentially an engine which has undergone a  major rebuilding when  it would
 otherwise have been scrapped or replaced with a new engine.  It is difficult
 to apply the definition of reconstruction ("...replacement  of  a substantial
 majority of the existing facility's components...") to a stationary engine
 because substantial portions of large- and medium-bore engines are replaced,
 in practice, as a matter of routine maintenance.  That 1s,  stationary  (and
 industrial mobile) engines are currently given  several major overhauls  during
I/At the present time there is only one known domestic installation of
  engines burning residual fuel.
                                   5-7

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the normal life of the engine without any stimulus from emission regulations.
The problem, then, is to distinguish routine maintenance and overhaul from
the rebuilding of an engine to avoid a standard of performance.
       Large engines receive several minor and major overhauls during the
lifetime of the engine(21-24).  Minor overhauls are performed after 8,000 to
16,000 hours and include new rings, new or reground valves, and occasionally
new or rebuilt pistons.  After 20,000 to 80,000 hours of continuous service
these large-bore engines are given a major overhaul.^/  At this time the
cylinder liners (which are removable from the engine block) are replaced in
addition to the items covered under a minor overhaul.  Generally, the
cylinder head, the crankshaft, rods, main bearings and rod bearings will last
indefinitely; nevertheless, these parts do sometimes fail, usually due to
lubrication failures, which can occur when the oil becomes contaminated, or
to extensive operation at overload conditions.  However, the basic engine
frequently remains in service indefinitely.
       In reality, several factors discourage perpetuation of these engines.
First, it can become difficult to obtain manufacturer service and replacement
parts for older engines.  Second, power requirements change with time and
frequently dictate a larger engine or an alternative power source (e.g., a gas
turbine).  This is especially true with generator and compressor applications
which are the major uses of large-bore engines.  Third, improvements in engine
design have led to lower fuel consumption in newer engines, which favors
replacement of older, less efficient engines given the ever-rising costs of
fuels.
2/
-'Twenty-thousand'hours for large-bore, medium-speed (1200-rpm) spark
  ignition engines and 80,000 hours for large-bore, low-speed (<400-rpm)
  compression ignition engines.
                                   5-8

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       Medium-large power  (>500 hp but <100 hp/cyllnder)  diesel-fueled
engines also receive minor and major overhauls during their  life(25-28).
These overhauls, however,  are different than overhauls  performed  on  large-
bore engines because they  are patterned after maintenance practices  used  by
the truck Industry.  The minor overhauls  are termed  "kit" overhauls  and  are
performed on the engine where installed.  They include  replacement of the
pistons, rings, liners, valves, and injectors.  Major overhauls,  on  the  other
hand, require removal of the engine and include replacement  or  regrinding of
the crankshaft and replacement of the main bearings, gears,  cylinder heads,
and rods.  Although major  overhauls usually cost  less than one-third the
price of a new eng1ne(29), the problems of servicing older engines,  changing
power requirements, and Increasing labor  costs encourage  eventual retirement
of an engine.3/  However,  since it is current practice  to replace
substantial portions of these engines, 1t would be difficult to discriminate
between a major overhaul that was performed to avoid the  purchase of a new
controlled engine from one that was performed 1n  accordance with  a routine
maintenance program.

5.4    SUMMARY
       The preceding sections of this chapter have detailed  those engine
changes which an owner or operator might  undertake during Its lifetime.   It
is noted that both minor and major overhauls are  performed routinely and
usually the old parts are rebuilt to original specifications or replaced  with
Identical new ones.  Thus, such overhauls should  be exempt from the
regulatory consequences of being a modification or reconstruction, despite
      cost of an overhaul would have to be 50 percent of the cost of a
  new engine for an overhaul to be considered a "reconstruction" in the
  sense of having to meet a standard of performance(30).
                                   5-9

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the fact that substantial portions of the engine can be replaced.
Alterations are occasionally made to major components, such as pistons,
cylinder heads, or turbochargers and aftercoolers, or to the operating
parameters, such as timing, air-to-fuel ratio (beyond the manufacturer's
specifications or purposeful alteration), or fuel (when not among those
specified for use by the manufacturer), and these changes can cause an
Increase In emissions for which a standard of performance applies.  In this
case,  these changes constitute a modification and would subject the engine to
a standard of performance.
                                   5-10

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                          REFERENCES FOR CHAPTER 5

(1)  Federal  Register,  Volume 40, Number 242, "Standards of Performance for
New Stationary Sources:  Modification, Notification, and Reconstruction,"
Subpart A, 40 CFR 60.14, Tuesday, December 16, 1975.
(2)  Ibid.. Subpart A,  40  CFR 60.7.
(3)  Ibid., Subpart A,  40  CFR 60.15.
(4)  Ibid.. Reconstruction.
(5)  Ibid.. Subpart A,  40  CFR 60.7.
(6)  Ibid.. Subpart A,  40  CFR 60.14(e).
(7)  Ibid.. Subpart A,  40  CFR 60.14(c).
(8)  Youngblood, S. B.  (Aerotherm/Acurex) and C. L. Newton (Colt Engines),
private communication,  February  11 and March 18, 1975.
(9)  Youngblood, S. B.  (Aerotherm/Acurex) and A. L. Foltz, Jr. (Enterprise
Engines), private communication,  February 10 and March 18, 1975.
(10)  Offen,  G. R. (Aerotherm/Acurex), private communication (Information
supplementing July 26,  1974 Trip Report), July 26, 1974.
(11)  Youngblood, S. B.  (Aerotherm/Acurex) and Mr. Dick Kendal, Peterson
Tractor (Caterpillar dealer), Oakland, California, private communication,
February 14,  1975.
(12)  Hanley, 6. P. (General Motors Corporation),  "Marketing and Technical
Data on Reciprocating Engines for Stationary Applications," Attachment VI,
January 24, 1975.
(13)  Shaw, J. C. (White Motors)  letter to J. S. Fletcher (Aerotherm/Acurex),
dated November 14, 1974.
(14)  Hanley, G. P., Reference  12, Attachment IV.
(15)  Hanley, G. P., Reference  12, Attachment VI,  p. 2.
(16)  Hanley, G. P., Reference  12, Attachment VI,  p. 16.
(17)  Hanley, G. P., Reference  12, Attachment VI,  p. 14.
(18)  Hanley, G. P., Reference  12, Attachment VI,  p. 17.
(19)  Hanley, G. P., Reference  12, Statement, p. 7.
                                     5-11

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 (20)  Offen, G. R. (Aerotherm/Acurex) and J.  D,  Martin (Union  Carbide,
 Seadrift Plant, Port Lavaca, Texas), private  communication,  December  1.1,
 I •?/ "t»


 (21)  Offen, G. R. (Aerotherm/Acurex) and C.  L.  Newton (Colt Engines),
 private cormunication, March 3, 1975.

 (22)  Youngblood, S.  B. (Aerotherm/Acurex)  and  C.  L.  Newton  (Colt  Engines),
 Reference 8.


 (23)  Youngblood, S.  B. (Aerotherm/Acurex)  and  A.  L.  Foltz  (Enterprise Engines),
 Reference 9.

 (24)  Offen, G. R. (Aerotherm/Acurex),  Reference 10.

 (25)  Youngblood, S.  B. (Aerotherm/Acurex)  and  C.  Marone, Watson and Meehan
 (Cummins dealer), San Francisco,  California,  private  communication,
 February 11  and March 18,  1975.

 (26)  Youngblood, S.  B. (Aerotherm/Acurex)  and  spokesman, Clementina Rental,
San Francisco,  California, private  communication,  March  18,  1975.

 (27)  Youngblood, S.  B. (Aerotherm/Acurex)  and Mr. Dick  Kendal, Reference 11.

 (28)  Youngblood, S.  B. (Aerotherm/Acurex)  and L.  Zankich, N.  C. Marine
 (Caterpillar dealer), Seattle,  Washington,  private communication,  February 12,
 i y / D •

 (29)  Offen, G. R.  (Aerotherm/Acurex) and C.  L.  Newton (Colt Engines), private
communication,  March  3, 1975.

 (30)  Federal Register. Reference 1,  CFR  60.15.
                                    5-12

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                                 CHAPTER 6



                  ALTERNATIVE EMISSION CONTROL TECHNIQUES







       This section presents alternative emissions control  techniques  that



can be used to reduce NO  emissions.  Section 6.1 is a brief  review  of
                        A


the control systems that were discussed in Section 4.4,  indicating which



of the techniques are considered technically viable and  effective.   In



Section 6.2, the effectiveness of these techniques (percentage  NO  re-
                                                                 A


duction) and their associated fuel consumption penalties are  summarized.



Section 6.3 discusses the research and development effort  that  engine



manufacturers estimate is necessary to achieve NO  reductions from their
                                                 A


products.



6.1    REVIEW OF CANDIDATE NOV CONTROL TECHNIQUES
                             A


       The NO  emission control techniques discussed in  Section 4.4  are
             A


summarized in Table 6-1.  In general, these techniques require  an adjust-



ment of the engine operating conditions or addition of hardware, or  a  com-



bination of both.  Although these techniques are listed  separately,  they



can be used in combination (see Sections 6.2 and 4.4.10).   The  control



techniques described in Table 6-1 can be divided into three groups based



on the relative ease with which they can be implemented.   This  section



describes the techniques within each group and indicates which  control



approaches are considered technically viable.  These techniques will form
                                   6-1

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the basis  for establishing  standards  of  performance  for  exhaust NO
                                                                   A
emissions.
       The first  group  of controls  Includes  retard,  air-to-fuel changes,
decreased manifold air  temperature, and  derating.  As  discussed 1n Section
4.4, these techniques,  or some  combination of  them,  appear  to  be the most
promising  NOX control approaches  based on their  demonstrated effective-
ness and relative ease  of Implementation.  They  generally require only an
operational adjustment  or resizing  of some components  (turbocharger,
aftercooler, etc.).  The exception  1s derating,  which  would require addi-
tional units to compensate  for  decreased horsepower.   In general,  these
techniques will increase operating  costs because of  increases  1n fuel  con-
sumption.  Engine manufacturers have  also indicated  that changes in engine
operating conditions may lead to  increased maintenance.  For example,  one
manufacturer established that 4 degrees  of ignition  retard  on  a dual-fuel
engine resulted in a 24 percent decrease in  the  service  life of the ex-
haust valves (see Section 4.4.2).   No other  data have  been  presented,  how-
ever, that show adverse effects on  engine components for the promising
control techniques.
       As discussed in  Section 4.4, the  degree of  application  of any of
these techniques will be limited  by practical considerations.   For large
amounts of ignition/injection retard, fuel penalties are large and exhaust
temperatures increase.  This may  cause reduced exhaust valve life  or re-
quire valve material that can withstand  the  elevated temperatures
(>1200°F).
       Similarly, the amount of air-to-fuel  (A/F)  change is limited by
misfiring or detonation.  In addition, mutually  aspirated engines  may
                                    6-3

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experience  large  Increases  1n  fuel  consumption  particularly as A/F ratio
1s decreased  from stolchiometrlc.
       Manifold air  cooling  is  limited  by  the  ambient  air temperature.   At
maximum ambient conditions,  manifold  air temperatures  with a reasonably
cost-effective heat  exchanger  can practically  be  reduced  (after turbo-
charging) to  15 to 20°F  above  the ambient  temperature.
       The  primary limitation of derating  is the  competitive disadvantage
it places on  engines that must  compete  with non-derated models.   For
example, applications consisting of several engines may require additional
units to satisfy  total power requirements  as a  result  of  derating.  Never-
theless, the  data  in Section 4.4.1  have shown that a small  amount (40
percent) of derate can effect a large NOX  reduction 1n two-stroke
engines.  Derate, however,  is generally less effective In four-stroke
engines.
       As discussed earlier, manufacturers may  apply these  control  tech-
niques alone, or  in combination, to achieve a given emission  level.  The
particular combination and extent of control applied will  largely depend
on the engine model.   As was shown  in Section 4.4.10 this approach  1s
effective and can achieve low NO  emission levels.
                                A
       The second group of controls Includes exhaust gas  reclrculation
(E6R) and combustion  chamber modifications.  These controls  have  demon-
strated effective NOX reductions but will  require additional  development
and durability testing.   In contrast to the techniques discussed  in the
first group of controls,  E6R will  require additional hardware:  plumbing
to recirculate the exhaust and a heat exchanger to cool the  recirculated
gas.   Although a limited  number of EGR tests have shown effective NO
                                                                    A
reductions (see Section  4.4.6), there is concern that the necessity for
                                    6-4

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cooling the redrculated gas will lead to fouling the flow passages of the
cooling heat exchanger as well as the engine turbocharger and after-
cooler.  The tests conducted to date on large-bore engines have been of
short duration ( < 100 hours).  Thus, longer testing will be necessary to
establish the effects that cooling the recirculated gas will have on
maintenance practices.  One manufacturer of heavy-duty diesel truck
engines has rejected E6R because of excessive fouling (< 200 hours), and
another manufacturer believes the application of EGR must be limited to
non-aftercooled turbocharged and naturally aspirated engines with full-load
                                                             /I p^
EGR cutoff to prevent excessive smoke (>10- percent opacity^ '  '.
(EGR has been successfully applied in combination with other techniques on
gasoline-fueled engines.)  Therefore, large-bore engine manufacturers will
require additional testing of this technique to establish its effect on
maintenance practices.  Nevertheless, this technique is considered  a tech-
nically viable NO  control.
                 A
       Data from smaller-bore diesel engines indicate that combustion
chamber shape has a significant effect on NO  emissions (see Section
                                            rt
4.4.8).  However, none of the domestic large-bore engine manufacturers has
any experience with new or modified combustion chamber geometries.  Manu-
facturers have estimated that an extensive development program of 3 to 5
years would be required to establish the emissions benefits of such a
major engine redesign.  Since there is little experience with this  control
approach, it is not considered a feasible near-term alternative at  this
time.
       The third group of controls includes water induction, increased
speed, and catalytic reduction.  These techniques have serious technical
or cost limitations, have not been shown effective, or have  little
                                    6-5

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experimental data to demonstrate their effectiveness.  For example, water
Induction has shown significant NOX reductions (see Section 4.4.7), but
deposit buildup from untreated water, combustion products, and  lube oil
fouling have led manufacturers to reject this NOX control approach.
With respect to speed changes, limited data  Indicate that a speed  Increase
of 10- to 15- percent (with a decrease 1n torque to maintain  the same
power) results  1n NO  reductions.  This technique may  be effective for
                    A
electric generation applications because these engines operate  at  a con-
stant speed.  (New units would use different speed exchange gears  than  In-
stalled units).  However,  this approach could not be applied  to gas
engine driven compressors  because engine speeds  are matched with compres-
sor  operating speeds, varying  as much as 10 percent  in the  course  of normal
 operation.   Since the largest number of new large-bore engines are sold for
compressor  applications  in oil and gas production  and  transportation,  this
technique  is  impracticable.   Similarly,  limited  data  exists  for catalytic
reduction  of  NOV  emissions from  1C engines.  As  discussed  in  Section
                A
4.4.9,  this approach  would be  difficult  to  apply to  the oxygen-rich  ex-
 hausts  of  large-bore  engines  and  probably  would  be very expensive  (see
 Section 8.2.3).
        Therefore,  retard,  air-to-fuel changes,  derating, manifold air tem-
 perature reduction,  exhaust gas  recirculation,  and combinations of these
 techniques are  considered technically viable NOX control approaches.
 The following section summarizes the NOX reductions and fuel penalties
 associated with these techniques.
                                     6-6

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6.2    EMISSION REDUCTIONS AND FUEL PENALTIES FOR CANDIDATE NO  CONTROL
                                                              A


       TECHNIQUES



       In general, application of the technically viable NOX controls  is



accompanied by increased fuel consumption.  The NO  reductions and  fuel
                                                  A


penalties for these techniques were discussed in Chapter 4.4 and  are sum-



marized in Table 6-2.  In practice, an engine user may  apply more or less



of these controls, either alone or in combination in an effort to reduce



NO  emissions with a minimum  increase in fuel consumption.  Conclusions
  A


based on Table 6-2 are summarized below by fuel type.



Diesel



       The data show that retard alone, or in combination with either  in-



let air cooling or air-to-fuel changes, is an effective approach  for



diesel engines achieving NO   reductions of 28 to 65 percent.  EGR also
                           A


demonstrates a significant reduction  in NO  (33 percent) accompanied by
                                          A


only a 1-percent fuel consumption increase.  With the exception of  two



data points, these NO  controls result in less than a 10-percent  fuel
                     A


penalty for all diesel engines.



Dual-Fuel



       A number of control techniques prove effective when  applied  to



dual-fuel engines.  Retard and air-to-fuel changes register the largest



NO  reductions (up to 73 percent).  Fuel penalties are  always less  than
  A


10 percent and in most cases  less than 5 percent.



Gas



       Similarly, several controls or combinations of controls were effec-



tive on gas engines.  Maximum NO  reductions ranged from 40 to 80 per-
                                A


cent accompanied by fuel penalties of 5 to 12 percent.  As  discussed  in



Section 4.4.3, changes in air-to-fuel ratios are particularly effective  in
                                    6-7

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  reducing NOX from gas engines.  This is because NO  emissions from
                                                    A
  spark-ignition engines are very sensitive to air-to-fuel ratio.   In fact,
  investigators have shown that derating, retard, and manifold air  cooling
  achieve NOX reductions from gas engines by, in effect, changing the
  air-to-fuel ratio^3^.
  Ranking of Controls
         The NOX reductions  summarized in Table 6-2 are  reorganized in
  Table 6-3.   The  techniques  have  been grouped into three levels  of NO
                                                                      A
  reduction:  0  to  20 percent;  20 to  40 percent;  and greater than  40 per-
  cent.   This  format readily  identifies which  control  techniques  have  estab-
  lished  given  amounts of  N0x  reduction.   The  table indicates  that  only
  retard  and  retard plus air-to-fuel ratio changes  achieve  NO   reductions
                                                            rt
 greater than 40 percent for diesel and  dual-fuel  engines.  Several tech-
 niques,  however, exhibit N0x reductions greater than 40 percent in
 natural  gas engines.   These results  are aggregated from a number of engine
 tests,  and not all engines within each fuel category have demonstrated the
 N0x reductions shown  at each level.  Nevertheless, several different
 techniques applied separately or in combination have been shown effective
 in  achieving significant  NOX reductions  (20 to 60 percent).
       These techniques are  summarized in Table 6-4 for specific levels
 (20,  40,  and 60 percent)  of  NOX reduction with the corresponding range
of  increases  in brake-specific  fuel consumption.   This  table  illustrates
that  a number  of  techniques  are capable  of  achieving  a  20-percent  NO
                                                                    /\
reduction for  engines of  all  three  fuels, and  fuel  penalties  are generally
less  than 5 percent.  Fewer controls  have been  demonstrated for  a  40-
percent N0x reduction, and fuel penalties are  larger, exceeding  10
                                    6-9

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percent 1n two cases.  In general, combinations of retard, air-to-fuel
ratio changes, and manifold air cooling were required for engines of  any
fuel category to achieve a 60-percent NOX reduction.  Fuel penalties
are highest for diesel engines, exceeding 20 percent.  Fuel penalties  are
more scattered for dual-fuel and natural gas engines, ranging from  1  to 22
percent but, in general, exceeding 5 percent.  The data  indicate that  re-
tard is the most effective N0y control for diesel and dual-fuel engines,
                             A
and that air-to-fuel changes are most effective for  dual-fuel and natural
gas engines.  The cost  impact of these alternatives  for  NOX emission
reductions will be discussed further in Chapter 8.
6.3    ESTIMATED TIME TO IMPLEMENT N0v CONTROL TECHNIQUES
                                     A
       Because manufacturers of  large-bore engines  are committed  to a
particular design approach, they conduct extensive  research,  development,
and prototype testing before releasing a new engine  model  for sale.  Con-
sequently, these manufacturers will  require  some  period  of time to  modify
or  reoptimize and test  engines to meet standards  of performance.   In
general,  this requirement  consists of  time to  accomplish the  following
tasks:
        1.   Establish baseline  (uncontrolled)  emissions  for all  engine
           models
        2.   Establish the effectiveness  of  various techniques  on each model
            and  size
        3.   Perform  durability  tests  on  selected  engines  for certain
            techniques
        4.   Engineer  any necessary redesigns, including new patterns and
            tooling
                                     6-12

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  As shown In Section 4.3, engine manufacturers have obtained uncontrolled
  emissions for about 80 percent of all dlesel, dual-fuel, and natural gas
  engine models.   Furthermore, engine manufacturers have expended consider-
  able effort to  Investigate potential NOX emission controls.  Therefore,
  the  time  requirements  for  areas 1  and 2 will  be  primarily to investigate
  the  effectiveness  of applying  a given control to a particular  engine model
  to meet a specified emission level.
        Manufacturers have  also  indicated  that a  minimum  durability test of
 2000 hours  is required for any  engine model whose  operating  or  combustion
 characteristics are modified.   For major design  changes, on  the other hand
 (e.g.,  combustion chamber redesign), they estimated a need for 8000  hours
 (about 1 year) of testing.
        Finally,  control techniques  that would require special hardware
 and/or  modification of  existing engine hardware would involve some engi-
 neering and  pattern and tooling efforts  as part of their  development.  EGR
 and combustion chamber  redesign  are  techniques that would require  this
 development.
        Table 6-5 estimates  the  time required to accomplish the four tasks
for all of the candidate control techniques identified in Section 6.1.
The entries in this table are based on the following factors:
       •   An estimate  of 9  months is required for all engines that need
           controls.  Since  not  all  manufacturers  own their own  emission
           measurement equipment (see Section  4.2.4) or have  data on the
           emissions of  their  current  production engines,  6 months  have
           been allowed  for  the  procurement  of  this  equipment, staff
           training, and the measurement  of  baseline emission  data  on  a
           variety of engine models.  An  additional  3 months  are  allotted
                                   6-13

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   to  analyze the baseline results,  consider the effectiveness of
   the  various controls  available for each engine,  and decide on a
   control  strategy.
   If problems  are  encountered  during the  long-term durability
   tests, the  problems need  to  be  corrected  and  some of  the tests
   rerun.  Therefore, 12 months  have  been  allowed for durability
   testing of major changes.  Since Internal E6R  is  not  as  signif-
   icant a change as external EGR or  a chamber redesign, only  8
  months were allotted for durability testing of this technique.
  Also, since there is  no reason to expect maintenance or dura-
  bility problems with  an engine that is operated at less than
  full  capacity,  no time is  allocated to durability testing of a
  derated engine.
  Retard and  air-to-fuel  ratio  adjustments require  no new hard-
  ware  and could  be implemented  after durability testing.   For
  EGR (internal and external) the  time to  assemble  new production
 equipment was scaled down from the  comparable  time for  a  com-
 bustion chamber redesign, again after considering  the  relative
 complexities of the various techniques.
 The time to develop a combustion chamber redesign  for a large
 engine was  estimated for large-bore engine manufacturers at 3
 to 3-1/2 years,  exclusive of durability testing and time to
 assemble the necessary  production tooling(4'5).  This esti-
mate,  in one  case,  is for a  redesign of the valves, injectors,
and piston head  and  is  based on  the  use  of  twice  the manufac-
turers 's current R&D resources  for this effort^).   Develop-
ment times for modified injectors, EGR, and water
                         6-15

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           induction were estimated by considering the potential technical
           difficulty with these systems relative to those of modified
           chambers.
       In summary, changes to engine operating conditions or the addition
of existing hardware could be implemented in 9 to 15 months, and a major
engine combustion system redesign would take 5 to 6 years.
                                    6-16

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                          REFERENCES FOR CHAPTER 6
(1)  S. B. Youngblood (Acurex) and Hanley, 6. P. (General Motors Corporation).
Private Communication.  May 19, 1975.

(2)  Henderson, R. D. (Caterpillar Tractor Co.).  Commentary on Diesel
Exhaust Emission Control System.  November 14, 1974.

(3)  Dletzmann, H. E. and K. J. Springer.  Exhaust Emissions from Piston
and Gas Turbine Engines Used 1n Natural Gas Transmission.
Southwest Research Institute.  AR 923.   May 19, 1975.

(4)  Fletcher, J. S.  (Acurex) and C. L. Newton (Colt Industries).
Private Communication.  November 3, 1975.

(5)  Offen, G. R. (Acurex) and F. S. Schaub (Cooper-Bessemer).   Private
Communication.  October 13, 1975.
                                   6-17

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                                  CHAPTER 7
                             ENVIRONMENTAL IMPACT

        This chapter  considers  the  environmental  impacts,  both  beneficial
 and adverse,  associated with the  control  of exhaust  emissions  from  stationary
 reciprocating internal  combustion  (1C)  engines.  The  candidate emission
 control  systems  are  discussed  in Chapter  4  and  are designed  primarily
 to reduce  NOX emissions  from large-bore stationary 1C engines.  The major
 emphasis  of this  chapter will  be to  identify the incremental impact as
 compared to uncontrolled engines of  these emission control systems  on
 air, water,  solid waste,  noise pollution, and energy  consumption.   In
 addition,  secondary  effects  resulting from these control  systems  (e.g.,
 increased  HC  or CO emissions as a  consequence of reducing NOX  emissions)
 will be  identified.  The  incremental impact of these  systems will be related
 to  uncontrolled engines  since  virtually no stationary 1C engines  are currently
 subject to emission  regulations other than for smoke.
 7.1    AIR  POLLUTION IMPACT
       The  discussion in Section 9.1 indicates that currently  installed
 stationary 1C engines contributed approximately 8.4 percent of the total
U.S. emissions of NOX.   Furthermore, large-bore engines (greater than
350 CID/cyl) contribute approximately three-fifths  of the NOX emissions
from stationary 1C engines, or  nearly 5 percent of  the nationwide burden.
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The projected impact of a standard for large-bore stationary engines  on
nationwide emissions will  be addressed in Section 7.6.   This section  will
evaluate the incremental  impact of the candidate NOX emission control
systems (identified in Chapter 6) on ambient  air quality.   To do this,
ambient air concentrations of NOX, CO, HC, SOX,  and particulates resulting
from emissions from stationary engines will  be estimated using an atmospheric
dispersion model.  Calculations will be performed for both uncontrolled and
controlled engine emissions under adverse meteorological conditions.   These
concentrations will then be compared with corresponding ambient air quality
standards.  The following sections will briefly discuss model plant charac-
teristics, the atmospheric dispersion model  used, and the results of the
calculations.

7.1.1  Model Plant Characteristics
       Data presented in Section 4.3 indicate the following range of  uncon-
trolled emissions for large-bore 1C engines:

                               Emissions, __g/hp-hr

                         NOx            CO              HCT
Diesel
Dual Fuel
Gas
5 - 18
4 - 13
8 - 29
0.5 - 8.5
1.2 - 4.5
0.2 - 29
0.1 - 1.0
0.8 - 5.7
0.3 - 5.8
       In general, CO is quite low in comparison with controlled mobile
diesel and gasoline engine emissions (the current federal CO standard
for heavy-duty vehicle diesel engines is 40 g/hp-hr; the California 1977
standard is 25 g/hp-hr).  Total hydrocarbon emissions for large-bore diesel
engines are about one-half those from currently controlled heavy-duty
                                    7-2

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  vehicle diesel  engines.   Also,  these  levels  are  about  one-half  the  levels
  that  will  be  emitted  when  automotive  (light-duty vehicle) engines are
  controlled to comply  with  the ultimate statutory limit of 0.41  grams per
  mile  specified  in the 1970 and  1977 Amendments to the Clean Air Act.
         Four typical large-bore  engine configurations were chosen for the
  atmospheric dispersion calculations.  In addition, a compressor station
  was simulated by modeling  the dispersion from a row of seven 1500-hp engines.
  Table 7-1  presents the physical  dimensions and emission source characteristics
  of all  these engines.   The NOX emission rates are given for  sales-weighted
  uncontrolled levels (see Section 4.3.4)  and for three levels of  control  cor-
 responding approximately to 20,  40 and 60 percent NOX reductions from
 sales-weighted uncontrolled levels.   The CO and HCT  levels correspond
 to values that most engines can  achieve  when  controlled for  NOX.   (See
 Figures  4-52 and 4-53.)
       An unfavorable  feature of the  designs  of  the five  prototypes  is
 that the height  of  the exhaust discharge  is not  significantly  greater
 than surrounding structures.   This causes  aerodynamic complications  which
 can seriously  interfere with  the rise of the  effluent plume,  thereby
 producing significantly higher ground-level concentrations.
 7-1-2  The  Dispersion Model and Meteorological Considerations
       The  dispersion model used to analyze these plants is  the single
 source model developed  by the Meteorology Laboratory,  EPA. The dispersion
 analysis  was performed  by Walden  Research Division of  Abcor,  Inc. under
 contract  to the Monitoring and Data Analysis Division  of EPA(1).
       In this  model  all  pollutants  are assumed to display the  dispersion
behavior  of  nonreactive gases. The  predicted  pollutant  concentrations
                                    7-3

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 are based on the application of state-of-the-art  modeling techniques,  which
 Implies reliability of the estimates  to within  a  factor  of about  two(2).
        The following assumptions  are  applied  1n the  analytical  approach:
        1.  There are no significant seasonal  or hourly variations 1n emission
            rates for these plants
        2,  The  plants  are located  1n  flat  or  gently  rolling terrain.   In
            restrictive terrain,  the dispersion  of  effluents could be more
            Impaired,  resulting  1n  higher ambient  concentration  levels
        3.  The  meteorological regime  is unfavorable  to the  dispersion  of
            effluents
        4.  All  engines are continuously in operation,  The  24-hour and annual
            ambient  concentrations  for engines which  do not operate con-
            tinuously will  likely be lower
        Preliminary  analyses  Indicated that, for the  stationary internal
combustion  engines,  critical meteorological conditions (I.e., those giving
rise to maximum  short-term  impact)  consist of a combination of stable
atmospheric conditions  and moderate wind speed.   If  such  conditions occur
frequently  at a  given  location,  especially if they are combined with a  high
directional  bias  in the wind, then  longer-term impact  (e.g., 24 hours and
annual) will also tend to be high.
        Stationary internal combustion engines also have a geographical
tendency  which must be considered.   A  large portion of these engines  are
located in the midwestern to southwestern United States.   Considering
these factors, Oklahoma City was chosen  as  the "worst case" location.
       The model is programmed to use  a  previously determined  set  of  dis-
persion conditions derived from  the basic meteorological  data  for  each
hour of the given year.  The calculations simulate the interaction between
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the  plant  characteristics  and these dispersion conditions to produce a
dispersion  pattern for each hour.  The computations are performed for
each  point  in  an  array of  180 receptors for any number of hours.  In the
case  of stationary internal combustion engines, the averaging periods
of  interest are 1 hour, 3  hours, 8 hours, 24 hours, and annual, depending
on the pollutant  of interest.
       The  prototype stationary internal combustion engines are modeled
with  aerodynamic  effects taken into consideration -- i.e., with a com-
putational  procedure that  accounts for the flowfield interactions between
the plume wind, and buildings.  Such effects were found to be critical
due to unfavorable design  (i.e., the exhaust discharge location is not
significantly  higher than the surrounding buildings).

7.1.3  Results and Discussion of Dispersion Calculations
       The results of the dispersion calculations are  presented in Table
7-2.  Maximum  short-term average (CO,  SOX,  HC, and particulates) and annual
average (NOX)  concentrations (at a distance of 0.3 kilometers from the
engine exhaust stack) are presented for the levels of  emissions listed
in Table 7-1.  Levels for CO and HCy that were used in the dispersion
calculation are typical of controlled  engines  (see Figures 4-52 and 4-53).
The potential   environmental gain from  a regulation based on the lowest
achievable levels of CO and HCj are discussed  in Subsection 7.1.5 below.   The
last column in Table 7-2 indicates the percent of hourly concentrations that
are greater than 50 percent of the maximum concentration during a 1-year
period.  National  primary and secondary ambient air quality standards
for these pollutants  are presented in  Table 7-3(3) for comparison with the
results in Table 7-2.
                                    7-6

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           TABLE 7-3.  NATIONAL AMBIENT AIR QUALITY STANDARDS!3)
Pollutant
N02
NMHCa
CO
S02
Parti cul ate
Averaging Time
and Method
Annual arithmetic
mean
3 hr: 6 - 9 a.m.
8 hr
1 hr
Annual arithmetic
mean
24 hr
3 hr
Annual arithmetic
mean
24 hr
Standard, yg/m3
Primary
100
160
10 mg/m3
40 mg/m3
80
365
75
260
Secondary
100
160
10 mg/m3
40 mg/m3
60
260b
1300
60
150
aNonmethane hydrocarbons
^As a guide to assess implementation for the  annual  standard
cAs a guide to assess implementation for the  24-hr  standard
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        All maximum concentrations for the model stationary internal combus-
  tion engine are noted at extremely close-in distances (0.3 km).  This is
  due to the aerodynamic effects on plume rise as well as to the relatively
  low height of the exhaust discharge.  These concentrations are estimated
  to fall off with greater distance at the following rates:
           Distance from source, km     Percent of the 0.3-km level
                      0.6                          33
                      1.0                          15
                      2.0                           5
                      5.0                           1.5
        The following subsections  summarize the  comparison  of  the  computed
 concentrations (Table 7-2)  with the  ambient  air quality standards  (Table
 7-3).

 7.1.4   NOy Concentrations
        The 1200-hp  dlesel  and  1500-hp gas  engines  are within  ambient air
 quality standards  at  both  uncontrolled  and  controlled emission  levels
 when used  individually.   The larger  gas  and  dual-fuel engines  (4300 and
 4400 hp),  however,  can exceed  the NOX standard  at their  uncontrolled and
 controlled levels but satisfy  this ambient standard when their  uncontrolled
 NOX emissions  are reduced 60 percent.  The group of seven 1500-hp engines
 (typical of a  pipeline compressor station) may exceed the standard at the
 uncontrolled level  and the controlled levels.  Thus, these large engines
 could cause the ambient air quality criteria for NOX to be  violated, at a
 distance where public exposure is  probable, even if emissions  were reduced
 significantly by controls.  These  violations would occur during the adverse
meteorological  conditions postulated for this analysis.   At typical
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uncontrolled levels  (15 g/hp-hr), the ambient air criteria would be met at
all receptors which  are further than about 1.0 km from the compressor
station.  The comparable distance would be less than 0.5 km 1f the seven
engines were all controlled to the lowest level Indicated.

7.1.5  00 and HC Concentrations
       Ambient air concentrations presented 1n Table 7-2 for CO are based
on representative levels of CO that all  engines for which data are available
could achieve when controlled for NOX emissions.  These calculations Indicated
that none of the engines exceed ambient  air quality criteria for CO.
This is not unexpected, considering the  relatively low emissions of CO
from these large-bore engines, which are designed to run at optimum thermal
efficiency.
       The HC input data to the model  were based on representative levels of
total hydrocarbons, including methane, that nearly all  engines were shown to
achieve when controlled for NOX.   Measurements by researchers indicate that
no more than 10 percent of the total  hydrocarbon emissions from gas engines
and 25 percent of the total hydrocarbons from dual-fuel engines are reactive
HC compounds(4»5).   When the concentrations reported in Table 7-2 are
multiplied by these fractions, only the  4300-hp dual-fuel engine and the
compressor station caused the nonmethane hydrocarbon standard to be exceeded.
Within 0.6 km of the station, the ambient air would not exceed the nonmethane
standard if the station were the only source.  Moreover,  if these gas engines
at the compressor station are assumed to emit total  hydrocarbons at a level
of 2.0 g/hp-hr,  as achieved by some  gas  engines,  instead of the upper limit
value of 5.0 g/hp-hr used for these calculations,  then  this station,  by
itself,  would not cause the nonmethane hydrocarbon standard to be exceeded.
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        Although some NOX emission control technologies cause HC and/or CO
 emissions to increase, the data in Figures 4-52 and 4-53 show that these
 increases are generally not large.  Thus, for dlesel  engines the NOX
 reductions were generally achieved with HC and CO Increased less than  0.2 and
 2 g/hp-hr, respectively (from uncontrolled levels of  0.1 to 1.0 g/hp-hr  for
 HC and 1 to 8 g/hp-hr for CO).   Similarly,  for dual-fuel  engines the
 Increases for both HC and CO  are usually less than  2  g/hp-hr (from
 uncontrolled levels of 1 to 6 g/hp-hr),  while for gas  engines  they tend  to be
 about 1 g/hp-hr (from similar uncontrolled  levels).   Carbureted or naturally
 aspirated gas engines,  however,  experience  greater  increases in HC and CO,
 since they operate closer  to  stoichiometrlc  conditions.
 7.1.6  SOv Concentrations
        The SOX  emission  rate  listed  1n Table  7-1  for the  dlesel  engine
 corresponds  to  a fuel  sulfur  content of  about  0.22 percent by weight.  This
 level  is  typical for  distillate  fuels.   By comparison, 0.5 percent  1s the
 maximum  allowable  fuel sulfur  content in several  states (e.g., Connecticut,
 Massachusetts (outside of Boston), and Rhode  Island).   Other areas  restrict
 the fuel  to  a sulfur  content  no more than 0.3 percent (e.g., Philadelphia,
 Boston,  and New Jersey).  Since the predicted ground level concentrations
 shown 1n  Table 7-2 are far below both the primary and secondary ambient
 air standards, they would still  be well  below these standards even 1f
 the fuel  contained  0.5 percent sulfur.   However,  if  one scales these computed
 results directly on emission rate (I.e.,  1f one assumes  that  doubling
 either the fuel  sulfur content or the engine size results In  double the
 ground level concentration),  any engine  larger than  5700  hp  could cause
a violation in the  secondary ambient  air  quality standard  (the  3-hour
                                          7-13

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standard 1s exceeded first in this case)  1f  1t burned fuel  with 0.5  percent
sulfur and 1f 1t were the only source.

7.1.7  Participates
       Partlculates are generally only a  problem with dlesel  engines.
As one can see by comparing Table 7-2 with Table 7-3,  the model  dlesel
engine does not, by Itself, cause the local  air to  exceed the  ambient
particulate standard.   Even the largest dlesel  engine produced 1n  the
U.S., a 13,500-hp unit, would just meet the  primary annual  and the secondary
24-hour standard if 1t were the only contributing source.

7.2    WATER POLLUTION IMPACT
       The promulgation of standards of performance should  have no significant
Impact on water pollution.  Only two control  techniques  could  result In
an additional discharge of water -- Increased manifold air  cooling and
water Induction.  However, since most newly  Installed engines  use  a  closed
cooling system(6), similar to an automobile  radiator,  the Increased  cooling
would be obtained by means of a larger radiator, a  higher speed fan, or
both.  Even where an open cooling system  1s  used -- e.g., a once-through
cooling tower -- no additional water would be discharged to streams, rivers,
lakes, or other groundwater systems.  The major Impacts  from  a cooling
tower are airborne mist and the demand for makeup water.
       If water Induction were chosen by  an  engine manufacturer or user
as a means of meeting a potential standard,  a demand would  be  created
for water, and there would be an airborne discharge of additional  water
vapor with the engine exhaust.  More importantly, however,  the inducted
water would require treatment to reduce total dissolved solids (TDS  --
see Section 4.4.7).  One researcher who investigated the effects of  water
                                          7-14

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  Induction on emissions and engine components  Indicated that  the  water
  available to him, which contained approximately  400 ppm of calcium
  bicarbonate, was unacceptable due to the  formation  of  combustion chamber
  deposits during dally operation^).
        Although raw water  sources and municipal  water  quality vary
  considerably,  typical  values  are  64  mg/£  IDS  for municipal water, and they
 should typically not exceed 500 mg/£ (-500  ppm)  of  TDS(8).  Any  water that is
 to be withdrawn for treatment  and distribution as a  portable supply 1n the
 Ohio River  Valley Water Sanitation District,  cannot  exceed IDS 750 mg/£ (at
 any time).   The corresponding  regulation  for  industrial water supplies
 (industrial  cooling and processing)  is  100 mg/£  TD$(9).  Therefore,  depending
 on the source  of  water to  be inducted  into the engine, the user may need to
 treat  water  ranging from less  than 100 mg/£ TDS  to several hundred mg/£ TDS
 before inducting  the water  into his  engine to reduce NOX.
        The wastes  associated with  this treatment would be required to meet
 local  regulations  before discharge to the environment,  According to one
 source(10),  the supplier of delonized water or a de1on1zat1on system assumes
 the  responsibility  of waste treatment and disposal  of solids  associated with
 the  water "softening"  process.  This disposal  problan is not  new  to  the
 engine  industry:  cooling water for large-bore engines 1s presently treated
 to reduce TDS which would otherwise accumulate as scale and reduce cooling
 efficiency.  According to the above source,  users presently neutralize
 their waste steams  and then drain  the treated  water  observing any local
 regulations that are in effect. Typical treatment and  disposal costs
 are  included In the costs of a water  treatment facility as discussed in
Section 8.2.3.   If a 10,000-hp  engine in continuous  operation (8000  hours
per year) used  water induction  at  400 ppm  TDS  and a  water-to-fuel  ratio
                                         7-15

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 of 1.0,  1t would add 5.8 metric tons/yr  of  solids  to the  stream  of  a waste
 disposal  facility.

 7.3    SOLID WASTE  DISPOSAL IMPACT
       The demonstrated  control  technologies  discussed  in Chapter 6  should
 also have  no Impact  on solid waste  disposal.  Some  control  techniques
 (e.g., EGR or water  induction) may  require more frequent oil changes  as
 a  result  of  oil  contamination.   According to  one operator of large-bore
 engines^1),  lubricating  oil is  changed every 40,000 to 60,000 hours,
 usually during a major overhaul.  In between, the oil is checked about
 once  a month for water and  fuel  content.  011 1s added periodically to
 replace that  lost through blowby and leakage.  Water communication necessitates
 an  oil filter  change  (normally changed at approximately 500-hour intervals)
 due to damage  of the  disposal paper element by the water.   Contamination
 of  the lubricant by the more volatile fuel requires an oil change because
 of  an explosion hazard.   There is no sludge, however, associated with
 oil filtering, and the discarded oil can be sold to an oil  reclaimer for
 $0.OS/gallon or burned as a waste fuel  in a boiler.
 7.4    ENERGY  IMPACT
       The annual incremental impact on national  energy consumption  can
 be  estimated based on historical  production  data  (see Section 9.2)  and
fuel penalties for candidate NOX emission controls (see  Section 6.3).
Table 7-4(12) presents the annual Incremental  energy impact  after 5  and
10 years  of a standard of performance.   A 10-percent fuel  penalty was
assumed for all new sales during this  period.  This  assumption  is  conservative
since many techniques discussed  in  Chapter 6 achieved large  NOX reductions
with less  than a  10-percent  fuel  penalty.  Thus, this  evaluation  1s  an
                                         7-16

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upper estimate based on an unusually high fuel  penalty,  and it is not
intended to apply to a specific emission level  or engine and control  combina-
tion.  Despite this assumption, Table 7-4 shows that the application  NOX
controls would cause less than a 0.07-percent increase in nationwide  consump-
tion of oil and gas after 10 years.
       Annual  production shown in Table 7-4 is  computed  as an historical
5-year sales average based on information presented in Section 8.1.   These
data show that sales of stationary engine horsepower that would be affected
by a standard of performance have been essentially constant over the  past
5 years and are assumed to remain relatively constant in the future.
Applications of these affected engines include  electric  generation for
diesel and dual-fuel engines, and oil and gas production or transportation
for natural gas engines.  All of these applications are  high usage,  estimated
as 8000 hours  per year.  Typical fuel consumption values are based on
the data from Figure 4-13.
       These assumptions result 1n an annual increase of domestic oil and gas
consumption of 0.0067 percent relative to 1972  total consumption.  This
penalty would increase to 0.034 percent after 5 years and 0.067 percent after
10 years, again relative to the 1972 total consumption.   If, however, total
consumption were assumed to increase by 3.5 percent per  year, the effect of
a 10-percent fuel penalty would cause the increase in domestic oil and gas
consumption to be only 0.029 percent of the nation's fuel consumption 5 years
hence, and 0.048 percent of the total domestic  usage in  10 years.
                                        7-18

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  7.5     OTHER  ENVIRONMENTAL  IMPACTS
  7.5.1   Noise  Impact
         Fan noise  levels from large-bore stationary reciprocating engine
  installations could increase as a result of increased cooling requirements
  if decreased manifold air temperature or precombustion chambers (which
  have higher heat rejection) are used to reduce emissions.  However,  in
 typical installations such as municipal generator plants, pipeline com-
 pressor stations,  or industrial process plants,  such increases in  the
 noise level are likely to be insignificant  in comparison to other  sources
 of noise (e.g.,  generators,  compressors,  pumps,  or  process  blowers).
        Although  stationary engines  are not  specifically  regulated  noise
 sources, seme engine installations mentioned  above may be subject  to  Occupa-
 tional  Safety and  Health  Act (OSHA)  regulations  or EPA guidelines  regarding
 noise exposure limits  for  employees.   Allowable  noise levels  and employee
 exposure times  are specified in parts  55 and  56  of the August  7, 1974,
 Federal  Register,  Volume 39, No. 153.   In any new Installation, measures
 should  be taken  as  required  to  meet these regulations.
 7.5.2 Thermal Pollution Impact
       The  application of emission controls can  increase fuel consumption
 with  no  corresponding increase  in power.  This additional heat input is
 discharged to the environment as waste heat  either by the cooling system
 or with the exhaust gases.  In  an attempt to identify the increment of
thermal  pollution caused by emission  control techniques,  two model  engines
are considered below.
       Figure 4-51  Illustrates  that the range  of  fuel  penalties  associated
with emission  control  techniques for  large-bore engines 1s about  1  to

                                        7-19

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10 percent,  The following data Indicates,  as  a worst case example,  the
additional heat discharged to the atmosphere  as a result  of  a  10-percent
fuel penalty for both a 500-hp and a 13,500-hp engine 1n  continuous  operation
(800 hr) for 1 year,  If a fuel consumption rate of  7500  Btu/hp-hr  1s
used for the uncontrolled unit, the heat  rejection 1s increased  by  about
15 percent.
                    Heat Exhausted to Atmosphere as     Increase  Due  to
                      Waste Heat from Uncontrolled         Control,
Engine
500 hp
13,500 hp
Engine, Btu/yr
20 x 109
535 x 109
Btu/yr
3 x 109
81 x 109
7.6    OTHER ENVIRONMENTAL CONCERNS
7.6.1  Irreversible and Irretrievable Commitment  of  Resources
       No irreversible or irretrievable  commitment of  resources  is  anticipated
as a result of promulgating standards of performance for  new stationary
reciprocating engines other than that already discussed resulting from
increased fuel consumption, and, possibly,  use of catalysts.

7.6.2  EnvironmentalImpact of DelayedStandards
       The environmental  impact of delaying a standard that  is based  on
emission levels achieved  by presently available control techniques  (see
Chapter 6) is essentially the same as the impact  of  no standard,  since
stationary reciprocating  engines are presently unregulated for exhaust
emissions except for local regulations for  smoke  and the  Los Angeles  area
NOX regulation.  The control techniques  which require  additional  develop-
ment (i.e., E6R on turbocharged engines, water induction,  and  combustion
chamber modifications) can potentially achieve lower emission  levels  than
those achieved by currently available techniques. However,  the  imposition
                                       ,7-20

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of  standards based on currently available technology does not preclude
or  Interfere with the continued development of the emerging techniques.
Moreover, the promulgation of a standard which prescribes an emission
level that is based on current technology to take effect several  years
hence would not lead to wasteful commitment of resources (i.e.,  does not
force engine manufacturers to expend large sums of money to develop one
kind of engine or control system now and a completely unrelated  kind for
the future); the technology is at hand to enable manufacturers to meet
a near-term standard, so that most R&D funds could be devoted to  preparing
for a lower, future standard.  Therefore, no environmental  gain  is achieved
by delaying promulgation of standards.
       The impact of no standard relative to a standard based only on
readily available control technology (i.e., a near-term standard) 1s dis-
cussed below.  The additional Improvement to the ambient air that can
be obtained 1n the future through the application of  more stringent standards
based on emerging control technology 1s also considered.

7,6,3  Environmental Impact of No Standard
       The estimated impact presented here for no standard  is based on
the same reasoning used for the  estimated energy impact (see Section 7.4).
Table 7-5(13) shows  the impact of a NOX standard for  1  year's production of
diesel,  dual-fuel,  and gas engines  that would be affected by a standard
of performance.   Three possible  levels  of control  (20,  40 and 60  percent)
are considered based on the alternatives  discussed in Chapter 6.   This
table shows  that  the impact of the  standard could range from 0.06 to 0.19
percent  of the  total  U.S. NOX emissions,  depending on the  level of control
Imposed.
                                        7-21

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          These  impacts  are  based on the  assumption of  constant production
   of  diesel, dual-fuel,  and natural gas  engines.
         Nevertheless,  several projections conclude that total U.S. NOX
   emissions fron stationary sources will increase at annual compounded rates
  of 3.9 to 6.4 percent(14,15).  These projecte(j .^^ ^ ^ ^
  economic indicators which  suggest a substantial industrial  growth during
  the next 10 to 15 years.   The growth in stationary source emissions  is
  partially offset  by declining NOX emissions  from  automobiles due  to  the
  application of controls.   When  both  trends are  considered,  total  nationwide
  emissions  (stationary  plus mobile) are  projected to increase by a factor
  of  1.2 to  1.4  by  1985.  Under these  circumstances, and assuming only a
  20-percent NOX reduction, the incremental NOX emissions impact in 1985
  for  all new controlled  large-bore engines (all fuels beginning in 1979)
 would amount to about 0.27 percent of the 1985 U.S.  NOX emissions fron
  all sources.   If a 60-percent reduction were  required  starting  in 1985,
 the differential  impact would rise to about 0.93 percent  in  1990.
        Industry spokesmen report  that 3 to 4  percent of the  present population
 of large-bore  engines  is being replaced each  year.  Assuming production
 remains constant and that a performance  standard for emissions is  in  effect,
 then  all of the present  population of engines will be replaced with controlled
 engines in 30 years.  This new population of  controlled engines (assuming
 controls achieve a 60-percent NOX reduction)  would effect a reduction in
total U.S. NOX emissions of  5.6 percent based  on present  (1974)  total
emissions  of NOX,  or a 2-percent reduction assuming NOX emissions  increase
3.5 percent  per  year over this period.
                                       7-23

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                          REFERENCES FOR CHAPTER 7


(1)  Modeling Analysis  of the Ambient A1r  Impact of Stationary Internal Com-
bustion Engines.   Report  prepared  by Walden Research Division of Abcor, Inc.,
for the Source Receptor Analysis Branch, Monitoring and Data Analysis Division,
OAQPS, EPA.   October 1975.

(2)  Ibid,   p. 1.

(3)  Title 40 - Protection of the  Environment.  National Primary and Secondary
Ambient A1r Quality Standards,  Federal  Register.  36 (84):  8187.  April 30,
1971.

(4)  Dletzmann, H. E. and K. J.  Springer.  Exhaust Emissions from Piston and
Gas Turbine Engines Used  1n Natural Gas Transmission.  Southwest Research
Institute.   AR-923.  January 1974.

(5)  Newton, C. L. (Colt  Industries), and  G.  R. Offen  (Acurex/Aerotherm).
Private Communication,  November 20, 1974.

(6)  Standard Practice for Low  and Medium  Speed Stationary Diesel and Gas
Engines.  Diesel  Engine Manufacturers Association.  New York, New York.
p. 70. 1972.

(7)  Shaw, J. C.   (White Motor Corporation).   Emission  Reduction Study on a
Carbureted Natural Gas Fueled  Industrial Engine.  Draft ASME Paper.  White
Superior Division.  November 1974.

(8)  Fair, G. M., J. C. Geyer,  and D. A. Okun.  Water  and Waste Water Engi-
neering.  John Wiley and  Sons,  Inc.   pp. 19-20.   1962.

(9)  Wastewater Engineering.  Metcalf and  Eddy,  Inc.   McGraw-Hill Book  Co.
1972.

(10)  Youngblood, S. B.  (Acurex/Aerotherm).   Interoffice Memorandum.  Water
Treatment System  Costs.  February 13, 1975.

(11)  Youngblood, S. B.  (Acurex/Aerotherm).   Interoffice Memorandum.
October 6-21,  1975.

(12)  Minerals Yearbook  1972.   U.S.  Department of the  Interior,  Bureau  of
Mines.  U.S.  Government  Printing Office,   p.  910.  1974.

(13)  Monitoring  and Data Analysis Division,  OAQPS,  U.S.  Environmental
Protection Agency.   Computer Printout of Nationwide Emissions  Report,
National Emissions  Data  System.  January 10,  1975.

 (14)   Hopper,  T.  G.  and  W. G. Marrone.   Impact of New Source Performance^
Standards on  1985 National Emissions from Stationary Sources,  Volume I final
draft report.  Prepared  by TRC for the Emission Standards  and Engineering
Division, OAQPS,  U.S.  EPA  under contract 68-02-1382, Task No.  3.
February  16,  1975.

                                     7-24

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(15)  Habegger,  L.  J.,  R.  R. CIHllo and N. F. Sather.  Priorities and
Procedures for Development of Standards of Performance for New Stationary
                                                      Nationai
                                  7-25

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                                   CHAPTER 8
                                ECONOMIC IMPACT
         This chapter is divided into four sections.  Section 8.1 presents a
  general  profile of the domestic stationary reciprocating engine industry.
  Emphasis  is given  to  large-bore stationary engine manufacturers and their
  major  end uses,  since  proposed New Source Performance  Standards (see chap-
  ter 9) will  affect  primarily  this  industry.   Section 8.2 is  a detailed
  cost analysis of the alternative N0x control  techniques  summarized in
  Chapter 6.   Section 8.3  is a  discussion of potential costs to stationary
  engine manufacturers and users  arising from other  environmental  regula-
  tions.   The  chapter concludes with a detailed analysis,  in Section 8.4,  of
 the economic impact that could  arise from the use  of the  alternative  emis-
 sion control techniques to meet a performance standard.
 8.1    INDUSTRY  PROFILE
        This  section presents  a business profile of the  1C engine indus-
 try.  It  is  divided  into  five  subsections.   In Section  8.1.1  manufacturers
 of  domestic  stationary  engines are  presented,  and general production
 trends  and applications are discussed.  In Section  8.1.2  the  discussion is
focused on the large-bore engine manufacturers.   A  detailed analysis of
large-bore engine markets is given  in Section 8.1.3.  Finally,  a  discus-
sion of engine imports and exports  is presented in  Section 8.1.4.
                                   8-1

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8.1.1  Structure of the  Industry
       The stationary  1C engine Industry  consists  of 40  firms  operating 1n
four separate submarkets:   (1) high-power,  low-to  medium-speed engines;
(2) medium-power, medium to high-speed  engines;  (3)  low-power, high-speed
engines; and (4) very  small one-cylinder  gasoline  engines  (<20 hp).   These
manufacturers were listed by submarket  1n Table  3-1.   Figures  3-1  and 3-2
depicted graphically the relationships  between the first three groups on
the basis of engine power.  All 40 firms  are  listed  In alphabetical  order,
with addresses, 1n Table 8-1.  In addition, engine descriptions are  given
1n Table 8-2* ' by manufacturer for all but some very small  gasoline
units.
       Table 8-3^ " '  shows total U.S.  production  of 1C engines by type
of fuel (gasoline, diesel, and natural  gas) for  the  years  1964 through
1975.  These data are  also presented  in graph form,  with a separate  plot
for each fuel, 1n Figures 8-1 to 8-3^5"6^.  These  data represent produc-
tion of all engines, irrespective of  whether they  were used  in mobile or
stationary applications.  Production  data of engines  sold  for  stationary
uses in 1973 have been estimated by direct contacts  with manufacturers
(see Table 3-2 and Section 8.1.3).  These data have  not been compiled
previously for public dissemination by  any government agency or trade
association, nor is there any reliable  basis for extrapolating the 1973
estimates to other years.  The reader should note  that these data  are for
shipments of engines produced by U.S. manufacturers  and do not consider
imports or exports.  For a discussion of  imports and  exports see Section
8.1.4.
       Several broad trends are indicated by these production  data:   (1)
Gasoline engine production grew slowly  up to 1974, with the bulk of  the
                                    8-2

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                             TABLE 8-1.  Continued
General Electric Company
Diesel Power Products
Transportation Business Division
2901 East Lake Road
Erie, Pennsylvania  16531
      Brand Name:  General Electric

Homelite Division of Textron
70 Riverdale Avenue
Port Chester, New York  10573
      Brand Name:  Homelite

Ingersoll-Rand Company
Engine Process Compressor  Division
100  West Chemung  Street
Painted  Post, New York  14870
       Brand Name:   Ingersoll-Rand

International Harvester Company
10400 West  North  Avenue
Melrose  Park,  Illinois  60160
       Brand  Name:  International

Jacobsen Manufacturing  Company
1721 Packard  Avenue
Racine,  Wisconsin  53403
       Brand Name:  Jacobsen

 John Deere OEM Sales
 Moline,  Illinois
       Brand Name: John Deere

 Kohler Company
 Kohler,  Wisconsin  53044
       Brand Name:  Kohler

 McCulloch Corporation
 6101 Century Blvd.
 Los Angeles, California   90045
       Brand Name:  McCulloch

 Murphy  Diesel Company
 5317  W. Burnham  Street
 Milwaukee, Wisconsin  53219
       Brand  Name:  Murphy Diesel
  O&R  Engines  Incorporated
  3340 Emery Street
  Los  Angeles,  California
        Brand  Name:  O&R
90023
                Outboard Marine Corporation
                Gale Products Division
                100 Sea Horse Drive
                Waukegan,  Illinois   60085
                       Brand  Name:   Lawnboy

                Sterling Engine Company,  Inc.
                3600 NW North River  Drive
                Miami, Florida  33142
                       Brand  Name:   Sterling

                Stewart  and  Stevenson  Services, Inc.
                4516 Harrisburg Boulevard
                Houston, Texas  77011
                       Brand  Name:   Stewart &
                                    Stevenson
                                    (Modified
                                    Detroit-Diesel
                                    Engines)

                 Tecumseh Products Company
                 Ottawa and Patterson Streets
                 Tecumseh,  Michigan  49286
                       Brand Name:  Tecumseh

                 Teledyne Continental Motors
                 Industrial Products Division
                 205 Market Street
                 Muskegon,  Michigan  49443
                 Brand Name:  Continental

                 Teledyne Wisconsin  Motors
                 1910  South  53rd Street
                 Milwaukee,  Wisconsin  53246
                       Brand Name:   Wisconsin,
                                     Hatz

                 Waukesha  Engine  Division
                 Dresser Industries  Inc.
                 100 West  St.  Paul  Street
                 Waukesha,  Wisconsin  53186
                        Brand Name:   Waukesha

                 White Construction
                  Equipment Division
                  White Motor Corporation
                  Hopkins,  Minnesota 55343
                        Brand Name:  Minneapolis
                                     Moline
                                      8-4

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 increased production occurring  in marine  and  garden  applications  (small
 engines, typically much  less than 15 hp).   The  1975  production, however,
 declined coinciding with a general decline  in the  economy.   (2) The  diesel
 fuel category experienced a much more rapid growth rate  up  to  1974 but
 also declined in 1975.  Note that the 1975  sales were nearly evenly  dis-
 tributed among construction, agriculture, generator  sets, and  general  in-
 dustrial applications.  (3) Natural gas engine production has  been declin-
 ing rapidly since 1966.  According to industry representatives this  sharp
 drop in sales of gas-fueled engines reflects the decline in usage of 1C
 engines for irrigation pumps and pipeline compressors^7).   (Ninety per-
 cent of the installed reciprocating engine horsepower in pipeline applica-
 tions is spark-ignited; slightly over two-thirds of the remainder is dual-
        (8}
 fueled)^ '.   This trend is  the  result of the unavailability of natural
 gas for irrigation  and the  end  of the nation's expansion of interstate
 natural gas  pipelines.
 B.1.2  Large-Bore Engine  Manufacturers
        The  large-bore  stationary engine  industry consists of nine  firms
 manufacturing engines  in  the  range of 400  to 13,500 hp  and  300  to  1200
 rpm.  In general, the  engines produced by  this  industry  are  designed  for
 heavy duty operation at high  power outputs and for  long  lifetime  (hence
 the  low  rpm  ratings).   The primary applications  of  these  engines are  for
 (1) oil  and  gas production, (2) oil and  gas  transmission,  (3) electric
 generation and (4) standby service (nuclear  power plants, standby  genera-
 tors, and floodpumps).  These applications are discussed  in  more detail in
Section 8.1.3.
       As shown in Table 8-4 the corporations manufacturing  high-power
stationary engines are all highly diversified,  and many are  among the 500
                                    8-15

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           TABLE 8-4.   MANUFACTURERS OF HIGH-POWER ENGINES
       Manufacturer

Alco Power Inc.

Caterpillar
Cooper-Bessemer
Superior
Ajax

Dresser-Clark Division
Waukesha Division

Enterprise  Engine  Division
of DeLaval  Turbine Co.

ElectroMotive Division
 Fairbanks  Morse  Engine
 Division

 General  Electric

 Ingersoll-Rand
Parent Corporation

G.E.C. Limited

Caterpillar
Tractor Co.

Cooper Energy
Services


Dresser Industries


TransAmerica
 General  Motors
 Corporation

 Colt  Industries
 General  Electric

 Ingersoll-Rand
     Rank in
"Fortune's 500"a

       NAb

       36
       340



       101


       NMC


       2


       178


       9

       117
 *Based on 1976 sales data    .                                J , „
 bNA = Not applicable, Alco Power Inc., Division White Industrial Power
  was purchased by G.E.C. Ltd of Great Britain, a conglomerate of
  engine manufacturers and related firms.
 CNM • Not meaningful since TransAmerica is primarily a financial
  corporation, rather than an industrial firm.
                                   8-16

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  largest  industrial  firms  in  the  U.S.   Seven  of the nine manufacturers of
  large-bore  engines  either  market gas  turbines  or belong to a parent com-
  pany which  markets  turbines  through  another  division.   Alco, General
  Electric, and  ElectroMotive  manufacture  engines  primarily for the railroad
  industry.   General  Electric  has  only  recently  begun marketing engines for
  stationary  applications, and primarily exports for drilling  and auxiliary
  power applications.  Some  of the  firms also manufacture large-bore engines
  for marine  propulsion and  mobile  applications  (e.g., off-highway  construc-
  tion vehicles).  As shown  in Table 8-5<10), all  Of these  organizations
  are part of diversified parent corporations for  which sales  of stationary
 reciprocating engines account for less than 15 percent  of  total revenues.
        Since 1973,  three firms -- Chicago Pneumatic, Nordberg, and
 Worthlngton  -- have ceased production of stationary reciprocating engines.
 Conversations with  industry spokesmen indicate that the Industry has  stab-
 ilized,  and  no additional  dropouts are anticipated.
        Manufacturing plants employ from 600 to 10,000 people each.  In the
 larger  plants that  produce  engines for other  than stationary applications,
 approximately 600 to 2000  employees  per  plant  can be  allocated to  manu-
 facturing  stationary engines.   Three  of  the nine  plants  which produce
 large engines  employ less than  1000  people.
       Sales  of high-power  stationary  engines  are comparatively unconcen-
 trated; the  largest  manufacturer  has approximately five-times the  dollar
 volume of the smallest.  Unit sales range from  about 20  to  200 units per
year for stationary  applications depending on the  manufacturer.
                                    8-17

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                    TABLE 8-5.  PARENT CORPORATION DATA


                                    Total Sales3             Rank  in 1976
   Parent Corporation               ($ millions)             Fortune 500


Dresser Industries                  $ 2,232                        101
(Dresser-Clark,
Waukesha)

Ingersoll-Rand                        1,922                        117

Colt Industries                       1,267                        178
(Fairbanks Morse)

Cooper Industries                       554                        340
(Cooper, Superior,
Ajax)

General Motors Corp.                 47,181                         2
(ElectroMotive Div.)

Caterpillar Tractor Co.               5,042                        36

TransAmerica                           NM^                         NM^
(Delaval)

General Electric                     15,697                         9
All Firms                           $554-47,181                  2-340
  ?Total sales are for 1976.  (Reference 10)
   NM = Not meaningful because TransAmerica is primarily a financial
   corporation, instead of an industrial corporation.
                                    8-18

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 In general, firms which make smaller engines have a higher unit volume.
 For example, the total engine sales of Caterpillar or Waukesha are many
 times that of any other manufacturer.  Furthermore, 90 percent of
 ElectroMotlve's sales are for locomotive power, and their stationary sales
 are comparable 1n number and dollar volume to their competitors.
        Industry representatives report that purchased materials account
 for approximately 60 percent of the cost of an engine.  Most manufacturers
 purchase large forglngs In finished or semifinished form, while some, for
 example, DeLaval  and Superior D1v1s1on/Cooper Energy Services, have their
 own facilities and make their own large castings.   Turbochargers,  after-
 coolers, radiators,  fuel  systems, governors,  oil  pumps and other auxiliary
 systems  are generally purchased from outside  vendors.
       Sales of high-power,  low-speed engines are  usually made through
 competitive bids  that Include a fuel consumption  guarantee and the cost of
 providing  a complete engine  Installation.   This most  commonly Includes
 foundations,  cooling systems,  and other components  such  as generators and
 compressors.   Often  the cost  of  the  basic  engine  1s  as little as 40 per-
 cent  of  the  total'11).  With  the  exception  of standby  service,  most
 applications of large-bore engines  are  high usage  (>2000  hr/yr).   Thus
 fuel  and maintenance  costs, rather  than  initial price, are the  most sig-
 nificant cost  Items for the purchaser of an engine.  Nevertheless,  manu-
 facturing  Industry spokesmen  Indicated  that engine prices  have  risen
 rapidly  due to  Increases 1n raw material and  labor costs.
       It  1s anticipated that the financial impacts on the manufacturers
of engines which must meet a standard of performance will  be  primarily  in
the form of research and development costs rather than costs  to modify or
retool the manufacturing process  (see Section 8.4).  Unlike standards of
                                    8-19

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performance for new sources that are applied to typical manufacturing pro-
cesses, the ones envisioned for 1C engines are directed at  the  product  of
engine manufacturers rather than at the plants.  Hence, controlling  engine
emissions will primarily involve modifications within  the product.   Al-
though attempts to reduce engine emissions may require additions  or  alter-
ations of one or two machines on an assembly line,  the costs  of retooling
that could be required for EGR  systems, new fuel pumps and  injectors,  new
head designs, etc., can be considerable.  Manufacturers have  advised us
that they usually  do not proceed with  the acquisition  of  the  new tools  or
machines until  the engine modifications habe been  thoroughly  tested  on
laboratory engines and their  durability verified'12'13'.
       Research  and development costs  are normally deducted from income
during the year  incurred  and  not  amortized  over  several years production
of  a  specific  engine;  however,  a  company's  engines are usually priced to
recover  these  overhead expenses.   Spokesmen for  large-bore engine manufac-
turers indicate that  the  R&D  programs  typically span 3 to 5 years but may
require  as  long as 10 years,  with about 1  year of endurance testing re-
quired before  any final  design can be  incorporated in a production
model^14).   The final  development work is  often carried out  in coopera-
 tion  with  a  well-known customer who receives the engines on  an economi-
 cally attractive basis.   The level of development work that  can  be  under-
 taken, however, will  vary depending on the manufacturer and  the  applica-
 tions the manufacturer serves.
 8.1.3  Stationary Markets for  Large-Bore Reciprocating Engines
        The principal  applications of  large-bore stationary reciprocating
 engines are listed below:
                                      8-20

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                     Application                    Type of Engine
           Oil  and  Gas  Production               Gas and Diesel
           Oil  and  Gas  Transmission             Gas
           Electric  Generation (baseload)       Dual-Fuel  and Diesel
           Standby  Service                      Diesel
 Oil and gas production applications consist of engine-driven  compressors
 for field gathering, pressurization, storage,  and distribution,  and  oil
 and gas transmission applications for engine-driven compressors  installed
 on natural gas pipelines.  Dual-fuel and diesel engines  are purchased
 primarily by municipal electric utilities for  baseload (continuous)  elec-
 tric generation.   Standby service includes emergency power for buildings
 and hospitals as  well as  nuclear generating stations and flood control
 pumps.   Miscellaneous applications of  large-bore  engines include auxiliary
 engines on construction equipment (e.g.,  hoists and dredges)  material
 handling,  and  pumping and electric generation  at  sewage treatment plants.
           Sales of  large-bore  engines  have increased slightly  from 1- to
 1-1/4-mniion  horsepower  per year  over  the past 5  years (1972  to 1976).
 Approximately  20- to 30-percent  of this horsepower 1s  exported,  primarily
 as  electrical  generator units  and  engine/compressors for  oil and  gas  pro-
 duction.   Exports have  increased during the past 5 years,  and  account for
more than  50 percent of total sales for one domestic manufacturer.  In
general, spokesmen  for manufacturers have  Indicated  that  rapid increases
in sales for export  and standby applications have  offset  depressed sales
for natural gas pipelines  and municipal electric utilities.
                                    8-21

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          The following discussion of engine application 1s subdivided by
fuel type since this classification provides a clear distinction of
end uses.  Aggregated sales Information are presented below for large-bore
engines by fuel type.  These data were compiled from responses of engine
manufacturers to a Section 114 Request for Information mailed 1n June of
1976 by EPA.(15)  EPA has decided not to release data for  Individual
manufacturers since manufacturers consider this Information proprietary.
8.1.3.1   Diesel Engine Markets
          The primary high usage  (large emissions  Impact), domestic  appli-
cation of large-bore dlesel engines during the past 5 years has been  for
oil and gas exploration and production.  These and other applications  are
Illustrated 1n Figure 8-4^16'21),  As this figure  shows, the market  for
prime  (continuous) electric generation and other Industrial applications
all but disappeared  after the  1973 oil embargo, but was  quickly replaced
by  sales of standby  electric units for building services,  utilities,  and
nuclear  power  stations.  The rapid growth  1n  the oil  and gas  production
market occurred because dlesel  units  are being used on  oil drilling  rigs
of  various sizes.   Sales of engines  to export  applications have  also grown
steadily  since  1972,  and are now  a major segment of the entire  sales
market.
          Some degree  of overlap  between  large-bore  diesels exists for
petroleum exploration  applications.   Smaller  (250  to  1000  hp)  medium-bore
designs  (e.g.,  Detroit  Diesel, Cummins,  and  Caterpillar) are  used on port-
able  drilling  rigs  to  drill  or service  2500-  to  5000-feet  wells.   These
rigs  are trailer-mounted or  helicopter-transported;  therefore,  small
 lightweight  (approximately 4000-lb)  engines  are  favored.  In  addition,
                                     8-22

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  utilization are shown for these two power sources, plus fossil steam and
  nuclear steam,  in Figure 8-5(23).   Note that the figure is based on 1968
  information;  however, the relative comparison of these prime movers is
  still  valid.  These results  do not include the cost Impact of standards of
  performance for gas turbines.   This impact is discussed in Section 8.4.1.3
         As  of  January 1,  1974,  six  new 1C engine generators were scheduled
  to be  added to  commercial  power  supplies --  five (total  32,840 kW)  1n  1974
  and one  (4415 kW)  1n 1975<24).   This  compares with six engines (30,930
  kW) added  in  1973.   The  Federal  Power Commission reports  that  as  of April
  1, 1977, 565,000  kW (39  units) of  diesel  and  dual  fuel  generating capacity
 were scheduled  to  be  Installed 1n  the  period  1977  to 1986^25^  Since
 most of the 1C  engines used for  electric power  generation  are  owned by
 municipal utilities, which are generally smaller than  the  investor-owned
 utilities,   1t is possible that uncertainties  in  fuel availability and cur-
 rent high Interest rates are preventing these smaller, municipally  owned
 systems from raising the capital  necessary to expand their systems.  A
 spokesman for  one manufacturer, however, stated that sales have picked up
 as  the  demand  for additional  power  has reached critical level.   In addi-
 tion, another  source believes  that  an  increasing number of engines will be
 used for onsite  power generation  by municipalities and  large industrial
 electricity users^).
        Large dlesels are  also  used  1n  nuclear  powerplants,  since these
 facilities  are required to  have emergency power  available  to flood the  re-
 actor core with  water  1n  the event  of  a reactor  failure.   Industry repre-
 sentatives  (both manufacturers  and  users) have indicated that the  high-
power diesel engines  have no effective  competition  for  this  market^27).
Due to the quick  startup requirements for nuclear power  (10  seconds  and
                                    8-25

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  load capability  1n  30  seconds),  this  service  1s  almost  exclusively met by
  large dlesel engines.  Since  safety regulations  require that  there be at
  least two engines for  each  reactor, the best  Indicator  of  future  engine
  needs by this market 1s a record of scheduled  construction  of nuclear
  power reactors,  Table 8-6  shows the  number of reactors scheduled  for com-
  pletion-'.  This Indicates  a market for 338 to 382 high-power  engines 1n
  the next 10 to 15 years.  Although recent difficulties  1n raising  capital
  and 1n proving the safety of reactors and spent fuel disposal  have  caused
 utilities to delay over 40 percent of the units under construction  or on
 order and to cancel  5 to 10 percent,  the Nuclear Regulatory Commission
  (formerly the Atomic Energy Commission) continues to project that  102,000
 nuclear  megawatts will  be constructed by 1980 and 250,000 by 1985(3°).
 It should be recognized that the engines for a particular reactor may be
 purchased up to a year  or two before  the reactor becomes operational.

             TABLE 8-6.   PLANNED CONSTRUCTION OF NUCLEAR  REACTORS

              Completed             Scheduled  as of January 1. 1974
             During 1973   1974   1975    1976   1977    1978    1979 & later

   Reactors       7        27      10       7      12       11     102

       Radar power stations  are  also served  by  reciprocating engines which
maintain precise  power  characteristics over  sizable load variations.
i/The source of this table^8* lists 169 units completed or  scheduled
  for completion after 1973.  Another source     mentions that 191 units
  are currently under construction or on order.
                                    8-27

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Engines have also been in demand by flood control districts for  pumping
applications along the Mississippi Delta.
8.1.3.2    Markets for Dual-Fuel Engines
       The concept of dual fuel operation was developed to take  advantage
of both compression Ignition performance and inexpensive natural  gas.
These engines have been used almost exclusively for prime electric  genera-
                 (31-34^
tion.  Figure 8-6v     ' illustrates, however, that shortages  of natural
gas and the 1973 oil embargo have combined to significantly reduce  the
sales of these engines in recent years.  For example,  sales of dual-fuel
engines in 1971, 1972, 1973, 1974, and 1975 were  95,  74, 53, 17,  and  35
units, respectively^ 5>  ).  As discussed above,  spokesmen for engine
manufacturers stated that sales have recovered somewhat as demands  for
power have become critical and firm commitments for fuel are established.
8.1.3.3    Markets for Natural Gas Engines
       The primary application of large  gas engines during the past 5
years has been for oil and gas production.  Figure 8-7^37" 2', based  on
manufacturer's data from responses to the June 16, 1976 Section  114 Re-
quest for Information, Illustrates that  75 to 80  percent of all  gas engine
horsepower sold during the past 5 years  was used  for  this application.
The primary uses are to power  gas compressors for recovery, gathering,  and
distribution.
       During this time, sales to pipeline transmission  applications
declined.  Combined with standby power,  electric  generation,  and other
services  (industrial and sewage pumping), these  applications  accounted  for
the remaining 20 to 25 percent of horsepower  sales.   The growth  of  oil  and
gas production  applications  during this  period corresponds  to  the
                                     8-28

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  Increasing  efforts  to  find  new,  or  recover  marginal,  gas reserves, and
  distribute  them  to  our  existing  pipeline  transmission network,  and store
  In covered, underground  reservoirs  near cities  for  peak  winter  demands.
        Figure 8-8 illustrates the number  of gas  engines  sold  for  five  size
 groups during the past 5 years.  The  large  number of  smaller  than  500-hp
 engines that were sold during this  period are primarily  one or  twocylinder
 engines used on oil  well beam pumps and for natural gas  well  recovery  and
 gathering.   Most of  the other, larger gas engines that were sold during
 this  period  ranged from 500- to 2000-hp.   In 1976, approximately 400
 engines in  this  size range were sold,  primarily for oil  and gas production
 (see  Figure  8-7).  Most  of these  gas engines were manufactured by
 Caterpillar, Cooper,  Waukesha,  and  Superior  Division of Cooper.
        Historical  sales  data for  pipeline  transmission and field compres-
 sor stations (see  Figure  8-9)<43) dearly  indicate the recent  market
 position for 1C engines  and  gas turbines.  Total  sales of 1C engines have
 been relatively constant  since 1970, while total  gas turbine sales  have
decreased dramatically with the recent slowdown of new pipeline  construc-
tion.   A breakdown of sales for transmission and  field applications  in
1975 (year ending June 15) is given
    Prime Mover              Turbine
Engine
Compressor
Horsepower
New
Additions
Total
Transmission
Stations
21,933
23,300
45,233
'••
Field
Stations
2,000
3,500
5,500
Transmission
Stations
4,080
78,800
82,880
———————
Field
Stations
29,400
30,450
59.850
                                   8-31

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       These data Indicate that new transmission pipeline projects are
almost exclusively equipped with turbine-powered centrifugal compressors,
while new field stations (gathering, recompresslon, storage) are powered
by engine-driven reciprocating compressors.  Widely varying  loads are en-
countered 1n these latter applications, and therefore, engine-driven re-
ciprocating compressors are better adapted to this service than are
turbine-driven rotating compressors.   In 1975 nearly 80 percent of the
total sales of reciprocating horsepower was for additions to, or replace-
ment of, existing compressor stations, while turbine sales were evenly
divided between new and existing compressor stations.  In some cases the
gas turbine sales to existing  stations have displaced reciprocating
engines.  This has occurred in growing compressor  stations or in facil-
ities where all the old engines reach  retirement age at the  same time  and
can be replaced more cheaply by one  large  turbine  than by several recipro-
cating engines.
       Engines used 1n  pipelines are concentrated  1n the major gaspro-
dudng areas, such as the Gulf Coast,  and  along the major natural gas
pipelines.  Pipeline construction  has  dropped  in the  last several years,
but applications to the FPC for pipeline construction  increased  during
1973  and  the  first half of  1974 as plans were  made to  exploit  the  natural
gas discovered  in Alaska'45'.   If  the  percentage of compressor  stations
utilizing  reciprocating engines remains  the same as in the  past,  this  will
bring an  increase  1n engine sales  over the next  several years  as pipeline
companies  purchase compressors to  move the gas.  The  exact  impact  is un-
certain,  however,  as firm  orders for equipment await  final  approval  by the
FPC.
                                     8-34

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          According to one major western on  company,  1n the past 10 years
   there  has  been  a movement  away from reciprocating engines used 1n refinery
   operations  to electric  motors,  steam turbines  for high-load requirements,
   and, occasionally,  fossil-fueled  turbines'46).   Moreover,  a plant
  manager from one  of the major  chemical processing firms,  who  utilizes
   large reciprocating engines to  compress  gases, believes that  large  power
  users will purchase gas turbines  In  the  future for fuel conservation
  reasons.  Most of these users can utilize the waste heat from  the prime
  mover,  and more  of this energy can be recovered economically from one very
  large turbine than from several large engines'47).
         Municipalities  use high-power, spark-Ignited engines to generate
  electricity from digester gas  in sewage treatment plants  and to pump
  water.   Competition  for  these  applications  comes  from  gas  turbines and
  electric motors.   As with electric power  generation,  1C engines have an
  advantage over turbines  for applications  when fuel costs are a significant
  portion of annual  costs.  Engines  are preferred over electric  motors  in
  areas where electricity  is relatively more expensive than  liquid or
 gaseous fuels and  1n applications  such as sewage processing  where  a by-
 product (such as  sewage gas) can be burned to supplement other  fuels.
 8.1.4  Balance-of-Trade
        The  U.S. Bureau  of the  Census (Department of Commerce) does not
 classify imported and exported  1C engines  Into  stationary  and nonstatlon-
 ary  applications.   Furthermore,  there are  no  priority  reasons for assign-
 ing  a  breakdown by  application  to either  imported  or exported engines.
 Therefore, information on  the balance-of-trade for  the  stationary engine
market is limited to the following  categories, for  which the  Department of
Commerce does report data:
                                    8-35

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      Imports:  Engines for agricultural machines; compression
                ignition engines; aircraft engines; bus,  auto, truck
                engines; outboard motors; and engines  not elsewhere
                classified  (NEC)
      Exports:  Diesel  engines  (automotive,  marine, and  NEC);  gas  engines
                other  than  turbines;  outboard engines; gasoline  engines
                 (marine,  automotive,  and NEC);  and 1C engines  NEC
       Imported stationary engines  would be  included in the "Compression
Ignition Engines," "Agricultural Machines,"  and  "Not Elsewhere Classified--
categories.   These categories also include engines used for marine and
construction applications.  For this reason  it is not  possible to de-
termine the exact number of imported stationary engines or the exact  im-
pact stationary source  regulations would have on  imports.
       The classifications  are  less of  a problem  for exports because  the
categories are more  narrowly  defined.   Furthermore, emission regulations
on future domestic engines  would only affect exported  engines  if the  U.S.
manufacturers  added  control devices  to all  their  engines  produced  in  the
U.S.  rather  than  maintaining  two  lines of  engines --  one for  regulated
engines and  one  for  unregulated engines.  Table 8-7<48>49) gives import
 and  export  data  for  the appropriate categories  of 1C  engines  during the
 fiscal  years 1969 to 1973.
        Except for 1972, the trade balance for 1C engines  has been positive
 at about $60 million to $75 million per year and  is improving.  It is  in-
 teresting to note that the average value of exported  diesel engines  is
 about  six-times  the average  value of  imported diesel  engines, while  the
 average value of exported  gasoline engines  is  about  one-third the  average
 value  of imported gasoline engines.   Using  1971  Commerce Department  price
                                      8-36

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data for the value of engines produced 1n the U.S. as a function of their
rated power, the following Information can be derived for 1973 Imports and
exports

Average value
Corresponding

per engine, $
average hp
Diesel Engines
Imports Exports
889 4996
60 300
Gasoline Engines
Imports Exports
148 49
11 6
Thus, future Imports of dlesel engines should  correlate  with  U.S.  demand
for small dlesel engines.  Most of  the dlesel-powered  portable  refrigera-
tion units  and underground mining machinery  1n the  U.S.  use  Imported
dlesel engines (51»52),
       Since International markets  for all capital  equipment  are highly
competitive, trade  balances  of engines may be  affected more  by  monetary
exchange  rates and  tariff  restrictions than  by price  changes  due to emis-
sion control systems.   Moreover,  based on the  average horsepower shown
above,  large-bore  engines  play an  Insignificant role  1n  the  Import or
export market  of  stationary  reciprocating  1C engines.
                                     8-38

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   8.2     COST ANALYSIS FOR CONTROL OF NO  EMISSSIONS
                                         A
          This section  presents  a discussion of the cost impact to the engine
   user  and manufacturer  of implementing  the viable NOX control options
   designated  in Chapter  6.   The  costs  to the  engine user  of purchasing and
   operating engines equipped with  selected  N0x  controls are discussed in
   Section 8,2.1.  The costing was  done on the basis  of information  supplied
  by the manufacturers and users,  and  is applied to  a  group  of ''model-
  engines that are typical of those used in a particular application.
         In Section  8.2.2 the costs to the manufacturers for the  implementa-
  tion  of the  alternative N0x controls (presented in Chapter 6) are dis-
  cussed.   These cost  considerations include additional manufacturing asso-
  ciated with  adaptation  of controls to existing designs and the costs of
  engineering,  tooling,  and verifying  the effectiveness of a particular
  control  approach.
        Section 8.2.3 presents those costs  associated  with  emerging control
  techniques.   !n Sections  8.2.4, 8.2.5 and  8.2.6 costs associated with  fuel
 pretreatment, modified facilities, and  reconstructed  facilities, respec-
 tively, are identified.
 8.2.1   New Engines
        The application  of N0x  controls will affect costs  to the engine
 manufacturer  and  the  engine  user.   The degree of the effect will  depend
 upon both  the amount  of  reduction  applied  and the  type of control
 applied.  As  was shown  in  Section  6.3, various  control approaches affect
 initial costs, fuel consumption, and maintenance differently.   Further-
more, manufacturers of stationary  engines may incur  different  costs  to
achieve a given N0x  reduction depending on  a number  of factors  includ-
ing:   (1)  their degree of advancement in emissions testing,  (2) the
                                    8-39

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uncontrolled emission rates of their engines, and  (3) the necessary R&D
required to produce engines which can meet proposed standards of perfor-
mance.  Therefore, the discussion of incremental costs  to employ NOX
controls for manufacturers and engine users will be treated  separately.
This  section will be restricted to  the  discussion  of  incremental costs
incurred by engine users,  and Section 8.2.2 will discuss  NOX costs rela-
ted to  engine manufacturers.
        To  illustrate the  effect of  NO   controls on costs,  "model"
                                     /\
engines will be  selected  to  represent major  end users of  diesel,  dual-
fuel, and  natural  gas  engines.   Baseline costs, comprised of investment
and operating  expenses,  will  be  established  for each model.   Computations
for these  model  units  will then  be  used to illustrate the range of incre-
mental costs  to  the  user resulting  from the application of  the NOX con-
 trol  systems  described in Section 6.2.   These  incremental costs will be
 illustrated for  several control  systems that achieve any one of three
 levels of NO  reduction (20 percent, 40 percent,  and 60 percent).  This
             A
 approach  is not intended  to be a comprehensive cost  analysis of all  pos-
 sible  NO  control systems; rather  it is  intended  to  illustrate a  range
         A
 of costs  that an engine user would  incur  to  achieve  a  given level of N0x
 reduction.  The discussions  are subdivided by  major  end  uses,  since  engine
 types  and costs  are unique to each  end use.
        Section  8.2.1.1 briefly describes  the models  selected to  represent
 major  engine  applications.   The  cost analysis  methodology is then discus-
 sed  in Section  8.2.1.2,  and  the  results of  the cost analysis are presented
 in Section 8.2.1.3.
                                      8-40

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   8.2.1.1     Model  Engines
         Four model  engines  have  been  selected  to represent the major appli-
   cations of  diesel,  dual-fuel, and  natural  gas engines.   (The applications
   were described  in  Section  8.1.3)   The  following paragraphs  briefly des-
   cribe these models.
  Diesel Engine Model:  Electrical Generation
         As described in Section 9.3.1, affected  diesel engines  are  large-
  bore,  exceeding a displacement of 560 cubic inches per cylinder.   Typi-
  cally these engines are used as  prime movers for electrical generators  in
  municipal  utilities.  These engines operate from 6000 to 8000 hrs/year
  (baseload)  and consume approximately 7000 Btu/hp-hr of operation.  Manu-
  facturers  of these  engines  include  Alco,  Colt, Cooper and Superior Divis-
  ion  (of Cooper), DeLaval, and  ElectroMotive division  of  General Motors.
  Dual-Fuel  Engine Model:   Electrical Generation
        These engines are  nearly  identical to the diesel  engines except
  that they burn predominantly natural gas  (typically 95 percent  of the
  total fuel heating value).  In general, these  engines operate more  effi-
 ciently than their diesel counterparts, consuming 6500 Bth/hp-hr  of opera-
 tion.  Manufacturers of affected  dual-fuel engines include Colt,  Cooper
 and Superior Division (of Cooper),  and DeLaval.
 Gas Engine  Model:   Oil  and Gas  Transportaion
        These  engines  are  installed on  pipeline  compressors for long-range
 transportation  of natural  gas.  They generally  exceed  1000 hp,  averaging
 3000  to 4000  hp.  Typical  annual  usage  is  8000  hrs,  and representative
 fuel  consumption  is 7000 Btu/hp-hr.  Manufacturers of  gas  engines  for this
 application include Colt, Cooper and Superior Division (of Cooper),
DeLaval, and Ingersoll-Rand.
                                    8-41

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Gas Engine Model;  011 and Gas Production
       These engines are Installed on compressors that gather,  store,  pro-
cess, or distribute gas from gas production fields.   (These  engines  gener-
ally burn gas that has been treated to reduce  the sulfur  content.)   As
described 1n Section 9.3.3, engines that would be affected by proposed
standards of performance range from 300 to 2000 hp.   An  average size
engine  1s about  1000  hp and consumes  about 8000 Btu/hp-hr.   These engines
are manufactured primarily by Caterpillar, Cooper and Superior, Waukesha,
and  Ingersoll-Rand.
8.2.1.2  Costing Model for Users of Stationary 1C Engines
        The  objective  of the cost analysis  is  to estimate how an engine
user's  life cycle  costs will  change with  the  application of NOX controls
for  the model  diesel,  dual-fuel,  and  gas  engines described in Section
8.2.1.1.  The  following  paragraphs describe  the cost analysis approach and
the  basic  assumptions that  are  used  to estimate the incremental costs cre-
 ated by NO   controls.  Section  8.2.1.3 will  then present the results  of
           A
 the  cost analysis.
 Methodology
        The costs of owning and operating a large-bore engine can  be repre-
 sented as follows:
                              TAG  = AIC + M +  F
 where      TAC =  total annual cost of ownership and  operation  of engine
            AIC =  annualized  initial  cost = initial  engine cost x capital
                   recover factor (CRF)
            M    =  maintenance costs
             F    =  fuel and lubrication costs
                                      8-42

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  The annuallzed Initial cost Includes capital recovery of the Initial in-
  vestment (assuming 100 percent debt financing), depreciation, property
  taxes,  and Insurance.   Capital recovery rates typically range from 15 to
  25 percent.   Conversations  with Industry spokesmen Indicate that a rate of
  20 percent 1s appropriate!/ for estimating  Installed engine costs for
  electrical  generation,  gas  production,  and  gas  transportation appllca-
        The procedure for computing the  Incremental costs of  various  NO
 control techniques  1s as follows:
        •   Estimate the Increase 1n the costs of AIC, M, and F due to
            NOX controls
        •   Compute the Increase 1n the total annual cost, TAC
        •   Present the results as (TACC - TACU)/TACU x 100 = percent
            Increase 1n TAC  where c -  controlled  and u » uncontrolled
 Basic Costs  and Parameters  for Cost Analysis
        Table  8-9  summarizes  the basic  Inputs for  computing  the  total  an-
 nual  costs of uncontrolled engines.  As  this table  Indicates, the  costs
 will  be presented  1n a brake  specific  format, that  1s,  1n $/hp-hr.  The
 Initial costs  are  normalized  by the output power  and  usage  rate to obtain
 $/hp-hr.  This format makes  1t  possible to compare ownership costs for a
 number of differently sized engines that are used 1n  the same applica-
 tions.  This  format also permits a direct comparison of the Incremental
NOX control  costs  among engines using  different  fuels.
                                  Ph^ical  life*  20^ear accounting
                                  ?  10-Percent  ^terest on debt,  and
                                   and  fixed
                                   8-43

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       As shown in Table 8-8, typical initial costs for diesel and  dual-
fuel electrical generation and oil and gas transmission engines  are
$150^55^.  (This cost is for the engine only, F.O.B..)  Costs for gas
production engines are estimated at $50/hp and are representative of
engines sold by Caterpillar and Waukesha'  '.  Total capital  investments
for installed electrical generation stations  are approximately $300/hp
(1976)'57'.  Current investments for  installed gas transmission  compres-
sor installations range from $318 to  $575/hp, and range up to $584/hp for gas
field stations^  '.  Thus, the cost increases computed  in  this section
will be considerably smaller when expressed as a percentage  of the  total
application investment.
       Maintenance costs for these engines have been estimated based  on
information supplied by engine manufacturers.  These costs are typical  of
engines  that operate continuously at  rated load.
       Fuel costs assumed for the electrical  generation  applications  are
representative  of costs of distillate oil  and natural  gas  transported both
intra- and interstate.  (The current  (1978) regulated  price  of  interstate
gas is $1.48 per Mcf.)  Lower gas costs  have  been  assumed  for oil  and gas
production and  transportation applications since  gas companies  own  these
facilities and  pay  less for  the  gas.   In  addition,  average gas  costs  for
these companines  are a  composite of  contracted  supplies of gas  that span
several  years'   '.   Fuel  consumption  estimates  are  average values based
on  the data presented  in  Section 4.3.1.   Note that  this analysis assumes
baseload or continuous  annual operation  («8000  hr/yr).  Figure 8-9 illu-
strates  the relative proportion  of  each  of these  items relative  to total
uncontrolled costs.  Fuel  and  lubrication costs  are the largest  fraction
                                     8-44

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       TABLE 8-8.   BASELINE  COST PARAMETERS  FOR  LARGE-BORE ENGINES
COST
PARAMETERS
Initial Costa>b, $/hp
Capital Recovery Factor
Annual Usage, hr/yr
Maintenance*
Parts, $/hp-hr
Labor, $/hp-hr
Total, $/hp-hr
Fuel Costc, $/106 Btu
Fuel Consumption, Btu/hp-hr
Lubrication8, % Fuel Cost
ENGINE M
DIESEL
(Electrical
Generation)
150
0.2
8000

0.0012
0.0018
0.0030
2.50
7000
5
DUAL- FUEL
(Electrical
Generation)
150
0.2
8000

0.0012
0.0018
0.0030
3.00
6500
10
3DELS
NATURAL GAS
(011 & Gas (011 & Gas
Transport) Production)
150 50
0.2 0.2
8000 8000

0.0012 0.0012
0.0010 0.0018
0.0030 0.0030
2.00 2.00
7000 8000
10 10
'Aggregated from confidential communications with engine manufacturers.

 Initial cost divided by  annual usage (8000 hr) and multiplied by the capital  recovery factor
 (0.2)  gives annuallzed cost 1n $/hp-hr.

cFuel  cost calculations for dual-fuel units assume fuel  consumption 1s lOOiS gas.  All fuel
 costs  based on 1977 Information.
                                       8-45

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  of total costs, accounting for 70 to 80 percent of the  total.   The  varia-
  tion 1s a result of the different engine and fuel costs assumed for each
  of the model applications.
         The capital and maintenance cost Increases resulting from the
  application of N0x controls are estimated in Table 8-9.  These estimates
  were aggregated from information supplied by engine manufacturers or ven-
  dors of auxiliary equipment.   Increases in  fuel consumption will be esti-
  mated for  various control  techniques based  on the information given in
  Table 6-4  of Section  6.2.
  8.2.1.3 Results  of  Cost Analysis
         A cost  analysis  based  on  the  preceding discussion was  performed for
  each  of the  four model  engines described  in  Section 8.2.1.1.   Total  annual
  cost  penalties  (as a  percentage of total  uncontrolled  costs)  were  computed
  for each model  engine and  alternative level  of  NO  reduction  (i.e.,  20-,
  40-,  and 60-percent reduction) for the  control  techniques that  were  dis-
 cussed  in Section 6.2.  Table 6-4 is repeated here as  Table 8-10 to  Illu-
 strate those techniques and their fuel  penalties for each level of control
 alternative and fuel  type.
        Fuel penalties are the major factor affecting cost increases for
 high usage  engines.   Table  8-10 shows that fuel penalties increase with
 increasing  level of control.   They also  vary with control type.  For ex-
 ample, derating results  in  substantial  penalties (>10  percent) for NO
 reductions  greater  than  20  percent.   Retard,  manifold  air cooling,  and
 air-to-fuel  controls,  however,  generally achieve NO  reductions at  a
                                                   /\
 penalty  less  than  10 percent.   It should be  noted that  the decrease in
 data  at  the 60  percent NOX  reduction  level is the result  of  both:   (1)
manufacturer's  inexperience with the  application  of controls to  the extent
                                    8-47

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 TABLE 8-9.   COST INCREASES  TO THE ENGINE USER RESULTING  FROM NO   CONTROL3
                                                                               /v
CONTROL
Retard
Alr-to-Fuel
Derate
Manifold
A1r Temperature
Reduction
External
Exhaust Gas
Rec1rculat1on
CAPITAL
None
None
Increase by ratio of rated
power to derated power (to
compensate for power loss)
Increase engine costs 1.5%
to achelve 100CF Inlet
air. Larger heat exchangers
cost assumes engine equipped
with Intercooler
Increase engine cost 5% for
plumbing, heat exchanger
and controls for 10-123S
redrculatlon.
MAINTENANCE
33% Increase 1n base cost due to 25%
reduced service life of exhaust valves for
dual-fuel engines
Increase of 0.0001/hp-hr for Increased
cleaning of turbochargers
Increase by ratio of rated power to derated
power (more units or cylinders to service)
D ) Increase $0.0005/hp/hr for cooling
DF) water chemical treatment (cooling
towers)15
G ) Increase $0.0001/hp-hr for Increased
) service of radiator and aftercoo1erc
Double parts for dlesel engines'1
Triple parts for dual-fuel and gas engines'1
"Aggregated  from confidential  communications with engine manufacturers.

 Cooling water from cooling towers  for dlesel and dual-fuel  engine must be treated to  prevent
 sludge and  scale buildup due  to  water "hardness".

 Closer tolerances to achieve  lower manifold air temperature will require more frequent cleaning
 and servicing of radiators and Intercoolers (or aftercoolers) of gas engines.

dD1esel  unit has fixed rate of EGR, dual-fuel, and  gas  units have a variable rate of EGR
 Charge for  parts Includes periodic replacement of  the  EGR system and Its controls.
                                             8-48

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necessary to achieve that level, and  (2) 1n some cases  the  Inability of a
particular control approach to achieve reductions  at this level.
       The differential control costs for the techniques shown  on  Table
8-10 are tabulated In Tables 8-11 to 8-14 for the  four  end  use  applica-
tions described above.  Table 8-15 1s a summary of these cost penalties.
In general, retard, manifold air cooling, air-to-fuel change, or some com-
bination of these achieved 60-percent NO  reductions for less than  a 10-
                                        rt
percent cost penalty for each application except diesel/electrlc genera-
tion.  The cost penalty for the diesel/electric generation, 60-percent
NOX reduction category, however, is based on data  from  tests of only one
engine model; therefore this result may not be representative of costs for
other engine models.
       The data in Table 8-15 indicate a wide variation in  cost penalty at
any level of NOX reduction.  Moreover, average cost penalties are  less
than 6 percent (with the exception of diesel engines) for a 60-percent
NOX reduction.  Nevertheless, average cost penalties increase as the
level of NO  reduction increases.
           A
       Since average uncontrolled N0v emission rates from engines  of
                                    X
different manufacturers vary, cost penalties to achieve a given alterna-
tive performance standard will also vary among manufacturers.   These dif-
ferential costs are important to identify so that  potential economic
impacts in various end use markets can be identified (see Section  8.4.1).
       Table 8-16 illustrates the cost penalties for each manufacturer and
fuel type for each of the three alternative levels of performance  stan-
dards.  In general, the maximum cost penalty for any fuel is less  than 10
percent with the exception of the 40- and 60-percent reduction  levels for
diesel engines.  The data for gas engines do not indicate differential

                                    8-50

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cost penalty ranges among manufacturers at the 40- and 60-percent  reduc-
tion levels; however, the variation within a cost penalty range  is large
enough (e.g., 2 to 7 percent) for cost differentials to exist  among manu-
facturers.  That is, two manufacturers could be in the 2- to 7-percent
cost penalty range and one could incur a 2-percent penalty while the  other
incurred a 7-percent penalty.  (The potential impacts of these differen-
tials are discussed in Section 8.4.1.)
       This observation also holds for the dual-fuel and diesel  cate-
gories.  The results for the diesel category indicate that Superior Divis-
ion of Cooper has a cost advantage.  However, Superior diesels are
smaller, and in general, serve smaller power applications than Colt,
DeLaval, or larger Cooper engines.  Futhermore, the data are based on
results from only one diesel engine model; therefore, the magnitude of
this penalty may not be representative of penalties for all of these
engines at this level of reduction.  The data from Table 8-16  is analyzed
in detail in Section 8.4.
8.2.2  Engine Manufacturers
       Manufacturers of stationary reciprocating 1C engines will incur  ad-
ditional costs due to the proposed standards of performance.  As discussed
in Section 6.3, these costs are a result of one or more of the following
activities that may be needed to manufacture engines which meet  standards
of performance:
       •   Extended testing to verify the effectiveness of a particular
           control  approach
       •   Development and application of NOX controls to existing
           engine designs
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       •   Engineering, tooling, and pattern costs  for  the  redesign  of an
           engine family
Costs related to these actions have been estimated  for  the  control techni-
ques summarized 1n Section 6.3 (technically viable  approaches  to  meet  pro-
posed standards of performance) and are shown on Table  8-17^60»61^.
These estimates are representative of the costs that manufacturers would
Incur to adapt each of the NOX control systems to an engine family
(I.e., group of engines with same air and fuel charging system and combus-
tion chamber geometry).  These figures include costs to test engines for
durability and to retool their production facilities where  necessary,  but
do not Include costs to purchase or manufacture components  placed on the
engine.  These latter costs are included in the user-oriented  cost analy-
ses of Section 8.2.1, which considered primarily additional  hardware costs
in the initial price.  The table also gives estimated times  to implement
the various control technologies.  It should be noted that  these  costs
will double if a manufacturer is required to meet emission  standards for
two types of fuel (e.g., diesel and dual-fuel).
       In general, manufacturers believe their present  overhead budgets
are sufficient for the development of the controls  shown on  Table 8-17,
with the possible exception of EGR and combustion chamber modifications
which will require considerably more development over a longer time.   As
shown in Section 4.3.1, all of the manufacturers have established baseline
emissions for most of their engines.  They believe  that  controls  such  as
retard, air-to-fuel, manifold air cooling, derating, and combinations  of
these approaches would be relatively simple to implement, although some
development time would be required to optimize a particular  approach and
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            TABLE  8-17.   ESTIMATED  COSTS  FOR ENGINE MANUFACTURERS  TO DEVELOP
                           NOX  CONTROLS, (BASED ON  REFERENCES  60, 61)
CONTROL
Retard, R
A1r-To-Fuel Change, A
Manifold A1r Temperature
Reduction, M
Derate, D
R + M
R + M + A
External Exhaust*
Gas Redrculatlon, EGR
Combustion Chamber
Redesign6
DEVELOPMENT TESTS*
TIME, HR COST, $
200 25,000
200 25,000
400 50,000
200 25,000
300 40,000
400 50,000
2,500 300,000
10,500 1,260,000
EXTENDED TESTSb
(DURABILITY)
TIME, HR COST, $
2,000 100,000
2,000 100,000
2,000 100,000
0 0
2,000 100,000
2,000 100,000
12,000 450,000
16,000 560,000
ESTIMATED
TOTAL COSTC, $
125,000
125,000
150,000
25,000
140,000
150,000
750,000
1,820,000
TOTAL
DEVELOPMENT
TIME3, MONTHS
•••••II ii 1 1 n 1 1 j
15
15
15
9
15
15
35
69
                   °f exp1oratory and development time to establish operation and

Jh1s estimate assumes that one technician  1s 1n attendance full-time during a test of a 2000-hp engine

 e^lmlSlt;!;6"^! e^lnriodeTSJmll"8' """"« ***' "< ^^ COStS'  Tota
dFrom Table 6-5.

"Estimates for development time and costs Include engineering and redesign of engine components.
                                                                                            T-774
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establish its durability.  Since several manufacturers have  less experi-
ence in emission control research than others, the costs and times  shown
in Table 8-17 for these techniques have been estimated conservatively,
taking into account the variation in emission control experience among
manufacturers.
       As discussed in Section 4.4, modifications of engine  operating con-
ditions, such as retard or air-to-fuel changes, may necessitate modifica-
tions of materials used for exhaust values and turbochargers,  if exhaust
temperatures greater than 1200°F (present material limits) are experi-
enced.  However, temperature data submitted with the emission  data  of
Appendix C do not indicate excessive temperature will be encountered for
the levels of retard and air-to-fuel changes reported.
       Research and development of NOX emission control techniques  that
require more extensive development and/or redesign (e.g., EGR  or combus-
tion chamber changes) are difficult to quantify.  They will  be determined
to a large extent by a particular manufacturer's experience  with emission
controls, the uncontrolled emission levels of his engines, and the  res-
ponse of a particular engine to the control technique.  Manufacturers have
indicated that the time required to incorporate major engine design
changes range typically from 3 to 5 years, but may extend to 10 years in
some cases'  •'.  This time includes initial design, endurance testing
(including 1 to 2 years operation in a real application, but under  close
monitoring by the manufacturer), and tooling-up (9 to 12 months).   It is
unclear to what extent the costs for these activities would  be added to
present R&D expenditures or absorbed into the existing budgets, thereby
displacing R&D that would have been undertaken in the absence  of emission
standards.
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          These issues will be addressed further  in Section 8.4 which  discus-
   ses the economic impact of both users and manufacturers of  1C engines sub-
   ject to standards of performance.
   8.2.3  Emerging Controls
          In  this  subsection,  the costs to  control N0x emissions from
   large-bore  engines  using exhaust  gas treatment, combustion  chamber modifi-
   cations, or  water  induction  are estimated.   None of these  systems  has been
   used  on a large-bore engine  for any  length of  time;  hence they cannot be
   considered for  immediate application.  At the  same  time  they are not
   dependent upon any technological breakthroughs  and should be  available for
  use within 6 years, given appropriate priorities in the R&D budgets of the
  engine manufacturers.
  Exhaust Gas  Treatment:   Ammonia/Catalyst  syctQm
         Even  though  no engine  manufacturer has reported on the application
  of  N0x  reduction  catalysts to large-bore  engine exhausts,  at  least  one
  source  considers  the reduction  of  N0x  by  ammonia injection over a
 precious metal (e.g., platinum) catalyst  as a promising control technique
 of the future (see Section 4.4.9)<">.  An estimate of the cost of  this
 technique is presented in order to provide a comparison with the costs
 presented in  Section 8.2.1 for the  other NO  controls.
                                            A
        The  above-mentioned source  reports  that approximately 2 cubic feet
 of honeycomb  catalyst  (platinun,-based) would  be  required  for  a 1000-hp
 engine  to ensure  proper operation of the system.   The cost of  the catalyst
was estimated  at $1500/cubic foot (in  1973).   Assuming  that the engine
costs $150/hp  and that the cost of the cata,yst  accounts for about onehalf
the cost of the whole system (container, substrate, and catalyst), the
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   less  than  5-percent  oxygen^65).   Large-bore reciprocating engine exhaust
   contains considerably more  oxygen (e.g.,  about 15 percent for gas
   engines);  hence NOX  reduction may be  less.
          It  is also  Important  to note that  the  consumption  of ammonia can be
  expressed  as a quantity of  fuel  since  natural  gas  is  generally used to
  produce ammonia.  Assuming  a conservative NOV  emission  rate  of 20
                                              A
  g/hp-hr, and engine heat rate of  7500 Btu/hp-hr, a heating  value  of 21,800
  Btu/lb for  natural gas, and a requirement for  approximately  900 Ibs  of gas
  per ton of  ammonia produced^,   then the ammonia necessary for  the
  catalytic reduction has the same  effect on the supply of natural  gas as a
  2-percent increase in fuel  consumption.  Additional fuel is required to
  operate the plant  which produces  the ammonia.
  Combustion  Chamber  Modifications
         Section 4.4  described  several chamber designs  that  have been  shown
 to produce  relatively  low NOX emissions from truck-size  engines.   There
 seems to be no technological reason why these  designs  cannot  be adapted to
 larger engines (careful engineering analysis and design  would be required
 to make the  transition).  Moreover, it  was noted in Section 4.4 that  a
 variable throat  precombustion chamber design had been adapted to a large-
 bore engine  in a  laboratory.   Therefore, an estimate of the costs  associ-
 ated  with such a  change is  presented.
        It is difficult  to estimate the  cost of  designing  a  new, major
 change  to an engine.   One large-bore manufacturer  estimates that a combus-
 tion  chamber redesign would require 4 to 5-1/2  years  to complete depending
 on the engine  design (2- or 4-stroke cycle  I,, this  .ase).   This  redesign
could affect  pistons, cylinder heads and liners, injection  components,  and
valves and would  require an  additional 12-month  endurance testing before
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the final design could be released for production.  This manufacturer
would not need to expand his facilities for such a redesign program;
nevertheless, he estimates the R&D expenditure would be in addition to
normal development work and on the order of 1-1/2 times their  typical
development costs.
       The estimate to be presented here comes from private contacts with
manufacturers of truck-size engines who have considered the advisability
of converting their direct-injection engines to precombustion  chambers.
They estimate an approximate development cost of $0.5 million,  and note
that this figure would be higher if their staff had not already developed
familiarity with precombustion chambers through previous experiences.  The
estimate is based also on the experience of Teledyne Continental  who
reported a $3-million development and retooling cost for a gasoline engine
with a new chamber and ignition system design to replace an existing pro-
duction moder   .  This engine is rated at less than 100 horsepower,
and several tens of thousands are produced each year (14,700 alone for
stationary applications in 1974).  Teledyne Continental's expenditure
probably represents an upper bound for the costs that a large-bore engine
manufacturer might face; his R&D costs might be more, but retooling
expenses should be significantly less.
       Based on this  information, we estimate that  it would cost a manu-
facturer of large-bore engines no more than $2 million to convert his
units to precombustion chambers or squish lips.  If one assumes that the
average manufacturer  in this group sells 50 engines a year, that the aver-
age rating of these engines is 1200 hp, that the cost of $150/hp applies,
and that the manufacturer should be able to recover such an investment  in
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   5 years, then he would have  to  increase the  sales price  of  his  engines  by
   nearly 5 percent.
          Presumably fuel consumption in these  redesigned engines  could also
   be 5 to 8 percent higher than it is for current models, just as in some
   precombustion chamber truck-size engines relative to their closest open-
   chamber equivalents.   In  that case,  the economic impact from a standard
   that  could  be met  only by such a redesign  would be  about  5 to 8 percent of
   the uncontrolled total  annual  costs for  engines used in continuous  ser-
   vice, depending on fuel penalty.
   Water Induction
         Research has Indicated  that the induction of  water  into the engine
  in quantities equivalent to the mass of fuel consumed can be effective in
  reducing N0x emissions'68-").  Reductjons  of approxfmate]y 6Q ^^
  in N0x have  been  demonstrated  on several  gaseous fueled engines, using
  »ater  to fuel  mass  flow ratios (,b water/lb fuel) of  nearly one.   In gen-
  eral,  no increase in fuel  consumption  occurred (see Chapter 4 and Appendix
  0.  However,  this research  indicated  that  serious maintenance and dur-
  ability  problems are associated with water  induction,  and  therefore, this
  control, technique has been omitted from the cost  analysis of currently
 available techniques (Section 8.2.1).
        Since  this  technology, however,  could become available in the
 future  after  further  testing with water treatment, different allowances in
 the  water injectors, exhaust  valves,  etc., costs  are estimated below  for
 this potential  technology.
        Testing  has shown that the  water must be deionized prior  to induc-
tion to remove minerals which would otherwise deposit  in the engine (e.g.,
on the intake  and exhaust valves) and adversely affect  performance'70).
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For a 1000-hp engine, approximately 1 gallon per rain- ute would be
required to obtain a water/fuel ratio of 1.  Deionized water could be
supplied in bulk with an appropriately sized storage facility at a price
of $15/1000 gallons, excluding the initial price of the  storage
facility^.  Based on the  information  supplied in Table 8-8, such  a
system would cause the total  annual  cost (including water treatment  and
disposal,  storage, and delivery  system)  for  a  1000-hp  gas or  dual-fuel
engine used  in continuous  service  (8000  hr/yr)  to  increase  about  8 per-
cent,  assuming no  additional maintenance.   Total  annual  costs,  however,
would  increase approximately 25  percent  if one made the  reasonable assump-
tion that  engine maintenance requirements would be doubled  (cleaning flow
 passages,  dewatering or  replacing lubricant, etc.).  Corresponding
 increases  for a similarly sized diesel-fueled engine would be approxi-
 mately one-half as much, since diesel fuel costs about  2.5 times more  than
 natural gas.
        If the water is deionized at  the engine location, the water  cost
 will be approximately $50/1000  gallons  for  a  system that supplies  1 gallon
 per minute(72).  Total  annual costs  for a 1000-hp  engine in  continuous
 service fueled  with natural  gas would increase approximately 15  percent
 for no engine maintenance increase  and  85 percent  assuming engine mainten-
  ance  costs  doubled.
        A  larger engine,  e.g.,  6000-hp,  would require a proportionately
  greater water  rate to maintain a water/fuel ratio of one.   A reverse
  osmosis  water  treatment system would be better suited  for this higher vol-
  ume application (,5 gallons per minute).  Based on a $50,000 investment
  for this  system and a raw water cost of $0.5/1000 gallons, the total
   nnual costs for a 6000-hp  gas-fueled  engine in continuous duty
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   (8000 hr/yr)  would Increase approximately 10 percent assuming no Increase
   1n  engine maintenance,  and 35 percent assuming maintenance charges doubled.
   Summary  of  Emerging  Control  Technique
         The  costs associated  with  an exhaust  gas  treatment  system (ammonia)
   and with combustion  chamber  modifications  are  comparable to  those  for
   derating and EGR (see Table  8-15).  Water  Induction  control  costs  appear
  to be generally higher than  for most  control techniques summarized  in
  Table 8-15,  especially 1f delonlzed water  1s not readily available  1n
  bulk,  and 1f maintenance Is significantly  Increased.
  8-2.4   Fuel  Pretreatmervfr
  Desulfur1zat1on
         Sulfur  oxides  arise  from the  nearly quantitative  combustion  of sul-
  fur  in  the fuel.  The fuels  traditionally  burned  1n  reciprocating engines
  (I.e.,  gas and distillate oil)  are low In  sulfur, nitrogen, and  ash.
 According to a recent survey, over 50  percent of  all  distillate  contains
  less than 0.3 percent sulfur, and the  average nitrogen content 1s about
 0.03 percent(73).
        As explained  in Section 4.4.13 of this report, large-bore dlesel
 engines are occasionally equipped to  burn crude or residual  fuel  oils.
 These generally contain  higher levels of sulfur than  the  more  commonly
 used  distillate fuels.*/   Therefore,  engines fired with  the  heavier
 high-sulfur fuels may  Incur  Increased control  costs above those outlined
 in Section 8.2.1 for NOX control  alone.   The purpose  of this section  of
the report 1s  to determine the cost of  possible  standards for  the  user who
burns residual oil.
                                    8-67

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   a 3.5-percent increase in total fuel costs.  Comparable increases for 0.5-
   and 0.8-percent  sulfur (over 1 percent) are 3.2 and 1.9 percent,
   respectively.
   Denitrification
         While  S02  in  the  reciprocating  engine  exhaust  originates exclu-
   sively from the fuel,  N0x arises  from  thermal  fixation  of  nitrogen  in
   the air and from partial oxidation of  nitrogen  in the fuel.   The  control
  methods evaluated in Section 8.2.1 were devised only for thermal  N0x and
  have been tested with the traditional clean fuels (natural gas  and distil-
  late oil), where nearly all  the N0x generated is thermal.  The  possible
  use of heavier fuels  suggests that fuel nitrogen may someday become a
  problem.
         Thus, the currently available  technology for  control of NOX from
  fuel  nitrogen  is,  like  that  for control of  S0x,  modification  of th'e
  fuel.  But whereas the  desulfurization  of residual oil  is practiced  delib-
  erately, denitrification  is  practiced almost inadvertently.   Some  nitrogen
  is removed as a byproduct of desulfurization.  The fraction removed  is
 consistently less than that of  sulfur but is rarely monitored.   Neverthe-
 less, nitrogen  removal occurs at no cost above that for sulfur removal.
 The fuel  is not sold  under a  nitrogen  specification,  and indeed  the refin-
 ers have  resisted  (successfully, in times of fuel shortages) such a speci-
 fication.   Moreover, desulfurization competes with  other  refining proces-
 ses  for the  Umited supply of hydrogen.   New developments  in desulfuriza-
 tion catalysts have the  incentive of reduced hydrogen consumption,  but  the
newer catalysts remove less nitrogen.  For the time being, then,  the  owner
of an affected facility cannot buy  low-nitrogen fuel by specification as
he buys low-sulfur fuel.   Low-nitrogen fuel can be used to help reduce
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NOV emissions but cannot be used 1n lieu of applying control techniques
  n
to the engines themselves to meet the standard because the standard(s)
win be based on test data from Installations burning the traditional
clean fuels.
       A standard of performance for NO  which failed to recognize the
                                       A
special problem of fuel nitrogen would create a bias against the  burning
of residual fuels.  One manufacturer Indicated crude or residual  oil  1s
used 1n place of distillate where a long-term commitment for the  heavy oil
1s at a price lower than distillate.  This  spokesman pointed out  that
since dlesel fuel 1s regulated  but not crude, the  price of crude  1s  not
necessarily  lower than  distillate.  In fact, crude oil must be  signifi-
cantly lower than No.  2 oil to  justify the  increased capital and  mainten-
ance costs  for  heavy fuel  handling^76'.   Furthermore, the  lack  of infor-
mation regarding fuel-bound nitrogen formation  and removal  precludes a
more comprehensive  discussion.   Therefore,  since  the proposed  standards
for dlesel  and  dual-fuel  engines  will  be based  on emissions  data  obtained
when  using  No.  2 oil,  compliance  with  the standards may  also  require oper-
 ation  with  No.  2 oil.
8.2.5  Modified Facilities
       As discussed in Chapter  5,  a user usually does  not  make physical  or
 operational  changes to an existing engine installation  which would
 increase Its N0tf  emission rate.  However, 1f he did, he  would be
                A
 required to conform to a standard of performance for new sources.  There-
 fore,  we will  briefly consider  the potential cost  impacts of such a change.
                                     8-70

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          Essentially the user contemplating a modification has two
   alternatives:
          1.   Make the modification, Including use of the most practical
              available control  technology (see Chapter 5) that prevents the
              emissions from Increasing as a result of the modifications
          2.   Buy  a  new engine,  or  alternative  power source,  which satisfies
              the  new  requirement for which  the modification  was  Intended.
              If a new  engine were  purchased, the  appropriate  standard  of
             performance would apply.
         Normally a user would contemplate a modification for one of the
  following two reasons:
         1.   To increase the power  output of his engine
         2.   To install newly designed  parts,  such as injectors or pistons,
             in place  of the old ones during an overhaul
 For example,  a user  might  wish  to install  a new  injector that  the  manufac-
 turer designed to  reduce smoke  or fuel  consumption.   Other  changes,  as
 discussed in  Chapter  5, could  include alterations  of  the cylinder  head,
 Piston, valve or porting configuration,  and manifolds.
        If these changes resulted  in greater N0x emissions, the user
 would probably rely on the  control techniques described in Chapter 6 to
 bring the modified  engine within standards of performance.   The cost
 impact would depend on the  initial emission level and the N0x emission
 level  after  modification,   if the  level  after  a modifications  in the
 same  range as  those from new, uncontrolled  units,  the  cost  increases  would
 also be similar to  those presented in  Section 8.2.1.   (Derating  is  exclu-
 ded as a possible control strategy since  power requirements at existing
facilities are fixed.)
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       At present there is insufficient data to judge the response of
older engines to NO  control techniques.  Some older engines are likely
                   A
to have emissions lower than a standard of performance for new sources,
and emissions after modification could also be less.  In other cases,  this
might not be so.  Therefore, it  is not possible to  state quantitatively
the economic impact for users who make  a modification to their engine  and
are then required to meet a  standard of performance.
       When  faced with the  need  to meet a  standard  as  a  result of  an
intended modification, an owner  or operator would normally weigh the cost
impact of  this  approach  against  that  of replacing his  existing  facility
with  a new one.   This  new engine would, of course,  meet  the standard as
well  as  satisfy his  new  need.   The  cost of a  major overhaul is  probably a
reasonable estimate  of the  maximum  price  of a modification-plus-alteration
to bring the engine  into compliance with  a standard of performance for new
 sources.  For a large-bore, low- or medium-speed reciprocating engine,
 this cost is typically less than one-third (see Chapter 5) of the purchase
 price of the engine.-/  Therefore,  to be competitive, an  alternative
 engine or power source would need to approximate this cost, taking  into
 account both initial and operating costs.  Thus, it is unlikely that  the
 user would substitute a different engine  (to comply with  performance  stan-
 dards) rather  than apply control technology  to his existing engine.
 -/A  spokesman  for  one  engine  manufacturer indicated that practically all
    the  development  of  design  changes for new engines occurred in-house with
    the  manufacturer incurring  about 90 percent of the cost for endurance
    testing  of  the  design  change.   Thus,  end user-evaluation of design
    changes  are rare,  and  hence,  those costs are not included in this
    estimate.
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 8.2.6  Reconstructed  Facilities
        In  large-bore,  lower medium-speed  engines  the  main housing,  or
 structure,  is never replaced during  the engine's  life,  but at  some  time or
 other almost every component may  be  renewed.   In  general,  the  various
 parts are  replaced at  different times, as they wear out  or break, but not
 at the same time  (except for parts replaced during routine maintenance and
 overhaul).  As noted  in Chapter 5, overhauls  are  performed routinely
 throughout an engine's life and,  therefore, should not be  considered  a
 reconstruction even though substantial portions of the engine  are replaced
 (generally with parts  identical to those originally installed).  There-
 fore, since reconstruction within the meaning  of  40 CFR  60.15  is not
 expected  to occur, there is no need for estimating the cost impact of
 standards on reconstructions.
        Industry spokesmen have expressed concern  that a  standard of per-
 formance  might  deter  the replacement  of older engines with newer, more ef-
             (78)
 ficient onesv   '.   It does  not  seem likely,  however,  that the potential
 cost  increases  due to a standard would affect that decision.  In fact, if
 one  accepts an  industry estimate that new  engines  consume about 75 percent
 as much fuel  as older  ones^79',  then  one can  show  that it is more cost
 effective to  purchase  such  a new,  efficient engine (i.e., one with a fuel
 consumption rate of 7500  Btu/hp-hr) for continuous duty than to simply
 maintain  the old one.   This is true even if the new engine is  burdened
 with  a 5-percent initial  and 80-percent maintenance cost  increase (e.g.,
 with  E6R) to represent  the maximum cost penalty expected  from  controls, if
 it is assumed that the  old engine  is  completely amortized,  and  if the  same
maintenance costs are assigned to  the old engine as to an uncontrolled  new
unit.   In  fact, the difference in  favor of the  purchase is  about  9 percent
on an annualized basis.
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8.3    OTHER COST CONSIDERATIONS
       This section identifies any costs incurred by large-bore recipro-
cating engine users as a result of environmental regulations other than
standards of performance for air pollution.  Such regulatory requirements
might concern solid waste disposal, water pollution control, or noise
control.  The purpose of this section is to identify Incremental costs
imposed by these regulatory requirements that may in some way  limit the
ability of the user to bear the cost of control techniques presented in
Section 8.2.
       Stationary reciprocating engines do not cause solid waste disposal
or water pollution problems.  Used lubricating oil is not considered a
solid waste because it is either sold to an oil recycler or burned as fuel
in a boiler.  The only conceivable source of solid wastes or contaminated
water from the operation of these engines might arise from water purifica-
tion and demineralization for a water induction control system.  These
wastes, however, are currently hypothetical since such systems do not now
exist; they may be used in the future if water induction is developed as
an emission control technique.  Treatment costs to prepare water for use
in engine jacket and aftercooler cooling systems are presently accounted
for in maintenance charges for these engines, and hence, have been in-
cluded in the analysis presented in Section 8.2.1.
       Similarly, no noise regulations are presently in effect specifi-
cally for large-bore reciprocating engines.  These engines are typically
installed in remote locations (e.g., gas pipelines) or separate buildings
(e.g., electric utilities and standby service) where remote control of the
engine or process reduces noise exposure.  In addition, mufflers are used
to reduce noise.  However, one manufacturer of large-bore engines has
                                    8-74

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  reported  that  complex  noise control  systems could be cost-prohibitive to
  an  Industry whose  manufacturers  only sell  a few hundred units per year and
  who  typically  have limited  staff and facilities for noise control research
      .  This  source reports,  nevertheless,  that  manufacturers  are  begin-
  ning to Incorporate noise control  Into their  research  and design  programs.
        End-users,  on the other hand,  have  been  faced with Occupational
  Safety and Health  Act (OSHA) regulations limiting worker  exposure  to  noise
  levels and EPA regulations for the protection of communities from  annoy-
 ance.  One source reports that noise control for engines  1n the 800-  to
 2000-hp range can cost as much as $10,000 to $30,000. <81)  The level of
 effort  to  meet  OSHA requirements  1s often unclear.  For example, simple,
 relatively cheap  devices  such as  earmuffs and earplugs can be used as a
 last  resort when  other  methods  of noise control  prove technically  unfeas-
 ible.   However, the definition  of technical feasibility 1s uncertain,  and
 depends on  the  circumstances  of each  particular  application.
        In conclusion, there  are no  other  regulatory  requirements that,  at
present, will limit  stationary reciprocating engine  user's ability  to
absorb incremental costs as a result  of standards of performance for air
pollution.
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8.4    ECONOMIC IMPACT
       This section analyzes the economic impacts  of alternative  standards
of performance for NO  emissions from large stationary reciprocating  internal
                     /\
combustion engines on engine manufacturers (Section  8.4.1),  gas and elec-
tricity prices (Section 8.4.2),  employment (Section  8.4.3),  and foreign
trade (Section 8.4.4).  These impacts have been evaluated for alternative
standards of 20, 40, and 60 percent below sales-weighted  average  emissions
of uncontrolled gas, dual-fuel,  and diesel engines.   The  extent of the
impact for each alternative, assuming retard,  air-to-fuel  change, or
manifold temperature reduction techniques are  used to achieve compliance,
is summarized in Section 8.4.5 and in Table 8-18.-/   The  following is a brief
description of the results of the economic impact  analysis.
       The capital budget requirements for testing engine models  are  an
estimated $5 million for a 60 percent alternative.  These expenditures will
be made over a two-year period and could be financed internally by engine
manufacturers from profits on internal combustion  engine  sales.   No  firm  is
expected to lose more than seven percent of its sales to  competitors.  Gas
turbine sales will not make additional inroads into sales of reciprocating
engines with the possible exception of diesel  engines used for electricity
generation.  The total U.S. electric bill would increase  by 0.3  percent
when controls are applied to all engines.  This level would not  be reached
until all engines are replaced (full phase-in  would take  about 30 years).
Localities using internal combustion engines exclusively  to generate
-/Other techniques-derate, combustion chamber modification, and exhaust gas
  recirculation -- are treated separately in this section.  This is done
  since there is little likelihood they would be employed to meet these alter-
  native standards.  In addition, their wide range of possible penalties and
  applications preclude meaningful analysis.
                                  8-76

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electric power, however, could face a maximum Increase of nine percent.
Delivered gas prices will Increase by 0.4 percent when controls are fully
Implemented.  No loss in jobs will take place nationwide.  Local  changes
will be minor because sales shifts among manufacturers will  not be large.
U.S. oil Imports will Increase by 0.6 percent when controls  are fully phased-
1n.  Total Imports of goods and services will Increase by slightly more than
0.1 percent.
40 Percent Alternative
       The Impacts would be similar to those above, but somewhat  less 1n
the cases of capital budget requirements, product price Increases, and im-
port Increases.  Capital budget requirements would be $4.5 million because
of the need to test fewer models; this is $0.4 million less  than  for a 60
percent standard.   ElectroMotive diesel  engines would still  be vulnerable
to gas turbine competition.  The increase in the total U.S.  electric bill
would be 0.1 percent.  The maximum increase for localities would  be three
percent.  Gas prices would increase 0.3 percent.  Oil imports would rise by
0.4 percent and total imports by slightly less than 0.1 percent.
20 Percent Alternative
       Capital budget requirements would be $4.1 million. The possibility
of any sales losses to turbine manufacturers would be remote.  The total U.S.
electric bill would increase by 0.1 percent, and the maximum increase for
localities would be three percent.  Gas prices would increase 0.1 percent.
Oil imports would increase by 0.2 percent and total imports  by less than
0.1 percent.
       Comparing the impacts among the various alternatives  -- 60, 40, and
20 percent — there is no evidence that any of the alternatives would cause
an extraordinary impact.  The following sections present a detailed dis-
cussion of the economic impacts that were considered.
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 8.4.1  Impact on Manufacturers
        The most direct economic effect of alternative  standards  of performance
 1s on the manufacturers of large stationary reciprocating  Internal  combustion
 engines.   This Impact Involves three  areas -  capital  budget  requirements,
 1ntra-1ndustry competition,  and competition with  gas turbines.
 8.4.1.1   Capital  Budget Requirements
        To Implement NOX reductions  for  their engines,  manufacturers will
 require capital  outlays to develop  and  test engine control techniques and to
 maintain  production of existing model engines  under emissions regulations.
 The size  of these outlays  will  depend primarily on the number of models each
 firm would need  to  test, the extent of  further testing required, the fuel
 prices  paid during  testing, and whether or  not adequate laboratory facilities
 were 1n place.  The  ability to  finance the  outlays will depend upon the
 profitability  of  the engine Hne and the ease with which the Initial costs
 could be  absorbed by the companies' current capital resources.
       A  precise estimate  of the outlays cannot be determined without a
 detailed  evaluation of  specific control levels by each company.   Certain
 models have uncontrolled emissions that already meet the 20 and  40 percent
 alternatives, although  not the 60 percent alternative.   These are shown
 1n Table 8-19.  Models  that already meet the alternative levels without
 controls would not require testing.   Other models  with  high uncontrolled
 emissions may be such a minor part of a company's  business  that the company
 would drop them rather than test them with controls.  The data as  collected,
 however, do not reveal  the importance  of individual  models  to  the  companies.
 Furthermore, it is also possible that  certain models would  not have to be
tested because of the test results  gained  from  other models.   The  amount of
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         TABLE 8-19.  THE CUMULATIVE NUMBER OF MODELS CURRENTLY ACHIEVING
                      VARIOUS ALTERNATIVE STANDARDS
Alternative Met
(Reduction from average
uncontrolled emissions)
60%
40%
20%
Uncontrolled


Diesel
0
3
6
11


Dual Fuel
0
1
1
5


Gas
0
1
2
23


Total
0
5
9
39
     Notes:  Totals include only engine models for which data are avail•
             able.  This includes 39 out of a total of 49 models.
previous testing and the stringency of the standard may also determine the
outlay required.
       As discussed in Section 8.2.2, two phases of testing are required by
the manufacturer to establish that an engine can meet an emission standard:
1) development and 2) extended durability tests.  The tests used as a data
base for this study will have met the development needs of manufacturers in
many cases.  However, where models must be controlled more than 40 percent,
additional development tests may be needed.  Such tests would cost about
$25,000 per model tested.  Ingersoll-Rand and Alco may need to establish
in-house testing laboratories at an additional  cost of $50,000 for test
instrumentation for each firm.
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         After development testing, engine models must undergo extended
  tests to prove the durability of emissions reductions and operations.
  These tests would be about three times more costly than the development
  tests.   As noted in Section 8.2.2,  the entire testing process  can  take  15-18
  months.   Several  models  can be  tested  concurrently,  though  several develop-
  ment tests might  be needed  before a  manufacturer can  select the  best control
  technique.   Overall,  development and extended  durability  testing would  cost
  about $100,000  per  engine model.  This  estimate is based  upon confidential
  correspondence  from two manufacturers;  it could overstate the actual  costs
  for  the 20-  and 40-percent alternative  standards (which would need fewer
  development  tests).
        The total number of internal  combustion engine models produced by each
  firm and the estimated capital budget requirement for testing to  satisfy
 standards of performance  are shown in Table 8-20.   The total industry bill,
 including the cost of establishing new  laboratories at two firms, would  be
 approximately $5,000,000  for a 60 percent alternative  (requiring  testing of
 up  to 49  models).  The bill  would be  about $500,000 less  ($4,5 million)  for
 the 40 percent alternative,  and  about $900,000  less  ($4.1  million)  for the
 20  percent  alternative, since  fewer models would need  testing (see Table 8-19).
       The  capital test requirements  would be regarded as an added expense
 for the manufacturers.  The expense would be measured against the profitability
 of  each engine line.  The larger the   profits, the smaller the burden of the
 expense.   Manufacturers would either  absorb the added expense by reducing
 profits,  pass it on to customers  in the  form of higher prices, or  drop the
engine line as an uneconomic  part of  the business.
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               TABLE 8-20.  ESTIMATED CAPITAL BUDGET REQUIREMENTS
                           TO MEET NOX STANDARDS OF PERFORMANCE
Manufacturer
Colt
DeLaval
Caterpillar
Waukesha
El ectroMotl ve
Cooper Industries
(Cooper & Superior)
Ingersoll-Rand
Alco
Number of Models8
7
5
2
4
2

24
4
_!
Capital Budget Requirements
for NOX Standards of Performance'3
$ 700,000
500,000
200,000
400,000
200,000

2,400,000
450,000
150,000
  All Firms
49
$5,000,000
aAn engine model 1s defined by a set of fuel, air charging, number of
 strokes, and displacement per cylinder (bore and stroke) parameters.
bBased on an average test cost of $100,000 per engine model.   Ingersoll-
 Rand and Alco will have additional  expenses of $50,000 each  to establish
 test laboratories.
       A  major question is whether the internal  combustion engine manufac-
turers will have the financial  resources from which to fund the initial
capital requirements.  They can be funded either externally by increasing
debt or internally by using current capital  budgets or allocating funds  from
the capital budgets of other divisions In the parent company.   Price increases
could be used in addition to these financing techniques to recover the
expenses over a number of years.   If manufacturers  were to seek to recover
the annual 1 zed cost of test outlays over a five-year period, on average  they
                                   8-82

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 would have to ratse engine prices  only one  percent  (ranging  among manufac-
 turers from 0.4 to 2.1  percent).
         Although any combination of  the above  financing  techniques could be
 used, engine divisions  are likely  to operate from their  own  internal resources.
 Unlike investments in new products or plants,  the capital test outlays would
 represent investments in  established lines  of  business and thus, would entail
 much lower risk.   Moreover, these divisions are small parts of their parent
 companies,  as  Table 8-5 in  Section 8.1.2 shows.  Therefore, raising debt or
 obtaining funds  from other  capital budgets would not be difficult for such
 an  investment.
        Although  the  precise capital   budgets cannot be determined without a
 detailed  evaluation  of a  specific control level by each company, as previously
 mentioned,  the prospects  for internal financing can be put in perspective by
 comparing capital  budget  requirements with the sales and profits of internal
 combustion  engine  operations.   This can be done in a rough manner by compar-
 ing  parent  companies' profits  as a percentage of sales (see Table 8-21)  to
 their internal combustion engine divisions'  additional  capital  budget re-
 quirements  as a percentage of sales.   The internal  combustion engine  divisions'
 test requirements as a percentage of  sales cannot be shown in order to pre-
 serve the confidentiality of sales  data disclosed by manufacturers.   However,
 in no case did the percentage  exceed  five percent of sales or the ratio  of  the
parent company's after-tax profits  to sales. This  is  true even  in  the case
of Colt or ElectroMotive where  parent company profits  fell  below  five percent
of sales during the 1975-1976  period.
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                      TABLE 8-21.  FINANCIAL RESOURCES
Consolidated Parent Firm of Profits as
Engine Manufacturer 1976
Ingersoll-Rand
General Motors (ElectroMotive)
Colt Industries
Caterpillar
Cooper Industries (Cooper & Superior)
Dresser (Waukesha)
TransAmerica (DeLaval)
General Electric
5.6
6.2
4.9
7.6
7.5
7.0
a
5.9
% of Sales
1975
7.0
3.5
5.1
8.0
6.5
6.2
a
4.3
           All  Firmsb                             6.4%      5.8%
         aTransAmerica is primarily a financial  corporation whose sales
          are not easily compared with sales  of products  of manufactur-
          ing corporations.

         bAyerage profit margin computed as a simple average for all
          firms for which data were available.

         SOURCE:  Securities and Exchange Commission Corporate  10-K
                  reports and annual  reports  to stockholders.
       Providing that the internal  combustion engine  part  of the  business

has approximately the same profit margins  based on sales as  the parent  com-

panies, this indicates that in the case of each manufacturer, the additional

capital budget could be financed with funds generated internally  from domes-

tic sales of large stationary reciprocating internal  combustion engines.   In

addition, testing expenses would not be subject to taxes which would  otherwise

be applied if the firm earned profits of that amount.  For example,  if
                                    8-84

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$100,000 of expenses were Incurred instead of realizing $100,000 of gross
profit subject to the marginal federal corporate tax rate of 48 percent, the
corporation would have $52,000 less cash flow and the U.S. Government would
receive $48,000 less taxes.   In effect, the expenditure would cost the corpora-
tion $52,000 rather than the nominal  $100,000 if it were absorbed from profits
and not passed on through price increases.
       In the event standards were set that required exhaust gas recirculation
or combustion chamber modification, the capital  budget requirements would
change.  Based on confidential correspondence with manufacturers, it is esti-
mated that test requirements for the industry would double -- to ten million
dollars -- and the testing time required would double or triple — to three to
five years.  Hence, although cost doubles, the time involved doubles or
triples.  This means that the annual  requirement stays the same or decreases.
This capital requirement would compete more for  a company's overall  resources
because it is larger and more extended.  If only one manufacturer had to incur
this amount, it might mean less resources for normal product development or
investment and thus some competitive  disadvantage.
8.4.1.2  Intra-Industry Competition
       Manufacturers would not have significant  differential  impacts for
alternative standards that require spark retard, air-to-fuel  changes, or mani-
fold temperature reduction.   If derate, exhaust  gas recirculation, or combus-
tion chamber modification were required, cost penalties among engines would be
disparate and might cause competitive shifts  in  the sales  shares of manufac-
turers.
       To identify whether or not significant changes in sales  would take
place,  the engine penalty data were analyzed  in  conjunction with confidential
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sales data for each manufacturer.   Worst-case  impacts were determined by
looking at the maximum variation possible  among  engine penalties in a partic-
ular market.  Where the range of penalties shown in Table 8-16 of Section
8.2.1.3 was small, such as In gas engines, one company would  not have an
advantage over another company.   For instance, at the 40 percent alternative
for gas engines It 1s possible that Waukesha could Incur a  seven percent
penalty and Caterpillar a two percent penalty or vice  versa,  since  both of
them would  Incur  cost penalties of from two to seven percent.^  The  maximum
differential  cost penalty for these two competitors in  the gas production
market is  then five  percent  (seven percent less two percent).
        Cross-price elasticities were then considered using the above results.
 One spokesman estimated  that, in  one of their highly competitive markets, he
 would expect a 10 percent increase in price to  lead to  a 20  percent decrease
 in sales.2/  Another spokesman, referring to  the internal combustion engine
 market as a whole, estimated that a five  percent increase in price would  not
 have  any noticeable effect on their sales, but that a 10  percent increase,
 even  industry-wide, would lead to a 10 percent decrease in  sales.  At  markups
 beyond 10  percent, we have no estimates of the price  elasticities,  but have
 assumed  that every one percent increase in price would  result in  a  two percent
 decrease  in  sales.
  i/It should be noted that just  because the data show that CateH" l
    have to reduce its emissions  by  an  average of 46 percent versus 33 percent
    for Waukesha, it does  not mean that the Waukesha penalty could not fall
    iSto the high end of the range and  the Caterpillar penalty  into the low
    end of the range.
  i/This assumes sales are in terms  of  dollars rather than  units.   If sales
    werl based on units, the impact  on  dollar  sales would be  less.
                                      8-86

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        A third factor considered was the Importance of each market to the
 companies' total Internal combustion sales.  If standby and export markets
 (which make up almost half of all large stationary reciprocating Internal
 combustion engine sales) are exempt from standards of performance, this
 would leave manufacturers with a substantial  part of their business unaffected.
 In addition, as described 1n Chapter 9.3, smaller bore engines  will be
 exempt from proposed standards of performance.   Therefore, only a  portion of
 a manufacturers'  engine sales will  be affected  by standards.  Thus differential
 cost penalties  arising from standards would lead to  only  limited Impacts  on
 sales shares.
        In  combining  these factors  1n  a  hypothetical  example, a  manufacturer
 Incurring  a  possible six  percent penalty  over his  competitors would lose  12
 percent of his  sales  1n that  market  (assuming the  worst-case cross-price
 elasticity), which might  be 25 percent  of his total  sales  to all markets  —
 hence, he would lose only three  percent of  his  total sales.  (It should be
 noted that these are  large stationary reciprocating  Internal combustion
 engine sales, not total engine sales or parent corporation sales which would
 make this percentage much smaller.)
       In addition, one manufacturer Indicated that parts  and services
 accounted for over 25 percent of his annual  sales.(82)   Since standards of
 performance would not affect the outstanding population of engines, parts,
 and services, revenues would provide a stabilizing factor  for all manufac-
 turers in the short run, though this would lessen over  time.
       In the following analysis  of intra-industry competition for  each of
the major submarkets, sales losses of more than  10 percent in any market were
used to identify significant effects.   For most  manufacturers, the  potential
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sales loss was considerably less  than  10  percent  in most of the submarkets
they participated.   Moreover,  these  potential  losses were constructed
from an admittedly extreme set of assumptions  concerning the penalty dif-
ferential, cross-price elasticities, and  cost  pass-through.  The exact
percentage of potential  sales  loss that could  occur under these conditions
was withheld to protect the confidentiality of the data.
8.4.1.2.1  Electricity Generation
       There are two markets to discuss in  the area of  electricity  genera-
tion.  The first is the dual fuel market  supplied by Colt, DeLaval  and  Cooper/
Superior.  Based on uncontrolled  emission data, DeLaval  has a  distinct  advan-
tage over Colt and Cooper/Superior at  the 20,  40 and probably  60 percent
alternative levels.  The maximum  differential  impact would be  six  percent,
but no manufacturer would lose 10 percent of its  internal combustion engine
sales at any of the three control levels.
       The second market is the diesel fuel market  supplied  primarily  by
Colt, DeLaval, Cooper/Superior, and  ElectroMotive.   Here, a maximum differ-
ential impact of 18 percent is possible at  the 40 percent level  of control
with ElectroMotive suffering the disadvantage.  Nevertheless,  ElectroMotive
has substantial mobile engine sales  for locomotives  which would  be unaffected
by proposed standards.  It  is important to  note that the 14-18 percent pen-
alties shown  in Table 8-16  are based on data from one  engine  model.  Such
limited  test  data do not necessarily reflect the range of  penalties for strin-
gent alternatives since not all  engines were tested.   Moreover,  it is  possible
that some models might be able to attain low levels of emissions only through
    i
techniques  like derate or combustion chamber modification  at much  higher
penalties.  These would be  outside the range shown in the table.  It is the

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  likelihood of such additional  penalties,  rather than  the  data  shown  in  the
  test sample,  that lead to the  possibility of significant  differential impacts
  at stringent  levels of performance  standards.   For  these  reasons, no firm
  conclusions can  be drawn  except  that even  with  an 18  percent differential no
  manufacturer  would lose 10  percent  of  its  internal  combustion engine sales.
  8.4.1.2.2   Gas Production
         Ingersoll-Rand, Cooper/Superior, Waukesha, Caterpillar, DeLaval  and
  Colt sell  internal  combustion engines to the gas production market.   As  pre-
  viously mentioned,  the average cost penalties for manufacturers would range
  from one to seven  percent -- a maximum differential  of six percent.   At
 worst, this would mean that the most any manufacturer  would lose would be
 12 percent of its sales in this market, but no manufacturer would lose 10
 percent of its internal combustion engine  sales  for  all  markets  at any of
 the three alternative levels.
 8.4.1.2.3  Gas Transmission
        Cooper, DeLaval, Ingersoll-Rand  and  Waukesha  sell internal combustion
 engines to  the gas transmission market.  Because the engines are  gas-fueled,
 cost  penalties are similar to those  in the  gas production market, and no
 manufacturer would lose  10 percent of its internal combustion engine sales
 at  any  of the  control levels.
 8.4.1.2.4   Other Markets
        All  manufacturers have sales to other markets.  These include  gas-
 fueled, dual-fueled, and diesel  engines.  However, the  applications  involved
 are diverse and comprise what are actually  many different segmented markets.
 It would not be accurate to characterize differential penalties  across such
diverse applications.  As noted  in subsection 8.4.1.2.3,  gas-fueled engines
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have a low differential penalty and therefore, would not Involve much change.
Dual-fuel sales to other markets are too small to have a significant impact.
Only Colt and ElectroMotive sell diesel engines to other markets.  Again, it
can be expected that the other markets for diesel engines include many
diverse applications.  For a 20 percent control alternative, the maximum
differential penalty would be five percent.  For 40 percent, the maximum
average penalty differential increases to 15 percent.  This still would not
result in a 10 percent loss 1n  internal combustion engines sales for either
firm, even if their applications overlapped completely.  For the 60 percent
alternative, the maximum differential  is only four percent for the two firms
 (but  is based on limited data).
8.4.1.2.5  Standby. Export, and Small  Engines
       Standby and export  sales of large stationary  reciprocating  Internal
•combustion engines accounted for 44  percent of all sales of large  stationary
 reciprocating  internal combustion engines  (by  horsepower)  in the years 1972-
 1976  for all the manufacturers.   In  addition,  data on  sales of  stationary
 reciprocating  Internal combustion engines  below  the  regulated size limits
 (see  Chapter 9.3)  were not available for this analysis.  Assuming  these
 applications are exempt  from proposed standards  of  performance,  possible
 percentage loss  of sales for each  manufacturer is reduced  further.  By
 focusing only  on a small  section  of the NOX emitting stationary reciprocating
 engine population  (which nonetheless emits the bulk of NOX from installed
 sources), the proposed standards  of performance affect less than half of the
 total stationary reciprocating internal combustion engine sales of manufac-
 turers.
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 8.4.1.2.6  Aggregate Impact on Manufacturers
        Because of the broad range of most control  penalties,  it 1s  not
 always clear whether the engine manufacturers will  gain,  lose,  or stay even
 In a given market.  This 1s especially true where  combustion  chamber modifi-
 cation, derate, or exhaust gas redrculation is  involved.   It is  reasonable
 to assume that the disadvantages some manufacturers  may face  in one market
 may be at least partly  offset by advantages they gain  in  another  market.
 This is highly dependent on the manufacturers' product mix and  the cross-
 price elasticities of each market.   It has  also  been shown 1n the previous
 subsections that the Industry as  a whole  is  buffered by substantial  sales
 on nonregulated  Internal  combustion engines.  The market segmentation within
 major markets  and the importance  of other application factors would  also
 soften any impacts.
        Of  the  seven  manufacturers studied for intra-industry impacts
 (Caterpillar,  Colt,  Cooper/Superior, DeLaval, Electromotive Division of
 General Motors,  Ingersoll-Rand, and Waukesha), only Colt and ElectroMotive
 appeared to have a clear disadvantage in more than  one  market  at certain
 control levels.  Partly because Colt's sales are  concentrated  in the highly
 competitive electricity generation equipment market,  and partly  because their
 nonregulated sales are not nearly as  significant  as  ElectroMotive's, Colt
 could potentially suffer the most significant intra-industry impact.
       Assuming that Colt, the most  vulnerable manufacturer, were  to suffer
the most extreme differential  in each  of the markets  in which  they partici-
pate, and assuming the worst possible  cross-price elasticities,  Colt would
suffer a loss  in  sales of about six percent.^/
  Across-the-board  standards of 20, 40, and 60 percent could result in six
  six,  and  five  percent sales losses, respectively, by Colt.              '
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       The conclusion that intra-industry impacts would be sustainable and
 not cause any major dislocations within the indsutry holds for the degree of
 control for which the test data represent comprehensive ranges.   At stringent
 levels for the standards (e.g., 60% reduction from uncontrolled  data), the
 possibility arises that some models might require expensive control tech-
 niques that would widen the ranges and differentials.   Only further testing
 can ascertain how significant this would be.   It is also possible that even
 at the most stringent levels of control, the  differential  impact might be
 insignificant.
 8.4.1.3  Competition From Gas Turbines
       To assess the possible inroads turbines might make  in the reciprocat-
 ing engine market as a result of performance  standards  on  new 1C engines,
 market structure, cost,  and other factors must be considered.  The three
 major markets for turbines  and reciprocating  engines (electricity genera-
 tion, oil  and gas production, and oil and gas  transport) are segmented  into
 several submarkets in which factors such as size, weight,  durability,  relia-
 bility, vibration, and ability to handle load  variations often dictate  the
choice of engine.  Previous experience with the vendor,  reputation, service,
and familiarity with existing equipment are usually important considerations
in the replacement market.
       Turbines  do not compete with reciprocating engines  based  on  annualized
costs alone,  due to their higher operating (fuel) costs, at  least not  in  the
normal operating range of reciprocating engines which is 6,000 to 8,000
horus per year.   As  Table 8-12 shows, reciprocating engines  controlled  to the
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   60 percent level are less expensive to own than even uncontrolled turbines,
   with one possible exception in the electricity generation market  U/
          Table 8-22 also shows that for all  the other markets,  even the  maxi-
   mum penalty which could be  imposed on internal  combustion engines would  not
   bring  the cost  of owning internal  combustion  engines  up  to that of turbines.
          Proposed  NOX NSPS  standards  for gas turbines used  in electricity
   generation  are estimated  to  increase  their cost by about  two percent, and
   for oil and gas  transportation and  production applications by one to four
   percent.  Consideration of the proposed NOX NSPS will not affect the con-
   clusions which can be drawn from this table.
              TABLE 8-22.   TURBINE VERSUS  RECIPROCATING  INTERNAL
                           COMBUSTION  ENGINES  BREAKEVEN  ANALYSIS

Application
Electricity
Generation

Oil and Gas
Transporta-
tion
Oil and Gas
Production

Fuel

dual fuel
diesel


gas

gas
Maximum Reciprocating
Engine Cost Penalty
(as % of total annual ized costs)
NOX Reduction Alternative
20%

6%
8%


7%

7%
40%

6%
18%


7% •

7%
60%

6%
18%


7%

7%

Breakeven3
for 6000 to
8000 hr/yr

35-39%
12-14%


13-14%

25-30%
 aTh1s represents  the total  annualized  cost  penalty which would  have  to  be
  eeoXuPaT?h??  "? T 1prOCft1,"? ;|"t«™l  coJbSstionyenginesTfore  they would
  equal  the  cost of uncontrolled  turbines.
— New Source Performance Standards were proposed for stationary gas turbines
   in the 3 October 1977 Federal Register, Volume 42, Number 191.
                                    8-93

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8,4,1,3.1  Electricity Generation
       Data shown 1n Table 8-22 of the cost analysis  section  Indicate  that
cost penalties of 14-18 percent could be Incurred by  some dlesel  engine
manufacturers due to controls,   One manufacturer, Electromotive,  would Incur
that penalty even at a 40 percent level  of NOV reduction,  For all  other
                                             A
manufacturers, turbines would still cost more,
       Table 8-22 shows that a  12-14 percent cost penalty would bring  dlesel
reciprocating engines used 1n electricity generation  up to the point where
they would have no cost advantage over uncontrolled turbines.  Since turbines
would only Incur about a two percent penalty for the  proposed NOX new  source
performance standard controls/  ' it appears that they would become competi-
tive with diesel reciprocating  engines.   This conclusion, however,  is  based
on only one data point used to  calculate the 14-18 percent diesel engine
penalty and, as such, should not be used as a decision criteria, considering
that some uncertainty exists at the greater control alternatives (60 and
40 percent) for which there are test data.  Furthermore, it is unlikely that
turbines would replace diesel engines in plants using banks of smaller recip-
rocating engines, unless the entire bank were replaced with one turbine.
       At the 20 percent alternative, turbines do not compete with the in-
ternal combustion engines on a cost basis.  As load factors decrease,  how-
ever, turbines become increasingly competitive due to their lower capital
costs as shown in Figure 8-11.  The formulas and methodology used to pro-
duce this and other  graphs  illustrating the breakeven points in Table 8-22
are shown separately on Table 8-23.
8.4.1.3.2   Oil and Gas Transportation
       Although  the  reciprocating  gas engines in gas  transportation lose  a
large portion of their cost advantage over  turbines  in  the high end of the

                                   8-94

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TABLE 8-23.  METHODOLOGY FOR CALCULATING THE BREAKEVEN CURVES FOR FIGURES
             8-10, 8-11, AND 8-12
Cost (in mills/kWh)    =    -          +    OM    +    P(E)
The breakeven factor for the cost penalty to reciprocating engines (X)
occurs where:
                OMt    +    P(Et)  -  XT    +   OMr
Solving for the breakeven factor:
                                P(Et)
 X =
     (CRF)K      +     OM     +
     Hr/Yr r          u r
 The  percentage  breakeven  cost  penalty    =    lOO(X-l), where:
      X   =   breakeven factor
      CRF =   capital recovery  factor  (i.e.,  .2  =  20%)
      K   =   installed cost  of engine  or turbine  ($/kW)
      OM  =   operating and maintenance cost  ($/kWh)
      P   =   price of fuel (i.e., distillate $2. 50/MMBtu;  gas $2. 00/MMBtu)
      E   =   heat rate  efficiency in  MMBtu/kWh
      t    =   turbines
      r    =   large reciprocating internal combustion engines
 ^Assuming a 20-year accounting life, 10 percent interest rate, and four  >
  percent fixed capital charge (includes  property taxes, insurance, administra-
  tion and overhead).
                                     8-96

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   penalty range presented in Table 8-22, they are generally used in different
   applications, and substitution would not be indent,  even at  the breakeven
   point of total  annualized costs.
          Gas turbines in  gas compression uses  serve primarily mainline transrnis-
   sion roles and  provide  power  1n new  installations.  Gas turbines are larger,
   so one  turbine  would provide  the same  power as several internal combustion  '
   engines.   When  existing reciprocating engine compression installations are
   expanded,  however, reciprocating engines are purchased unless  the old engines
   are scrapped.  Moreover, turbines power centrifugal  compressor  equipment,
  while internal combustion engines  power reciprocating  compressor equipment
  Hence, existing  stations would not  mix  or change  motive foms unless  they
  also changed their compressor  equipment.
        Furthermore,  turbines are not  as well suited for gathering, storage
  or  prescription  where  the flow is highly variable and the discreate power
  requirements are in the  range  that internal combustion engines  offer   Thus
  engines are typically located at the distribution end of pipelines, whereas'
  turbines are located on the main trunk lines.
        In addition, high  load factors  (characteristic of compressor applica-
 tions) favor the  more efficient internal  combustion engines,  especially as
 9as  prices rise.  Figure  8-12 shows  that internal  combustion  engines maintain
 this advantage, even  at load factors as  low as 1,000 hours per year.
 8.4.1.3.3  Oil and  Gas Production
        Turbines are clearly uncompetitive on purely a  cost basis  in this
market.  They are less efficient and  much more expensive than internal  combus-
tion engines and are primarily used on  offshore rigs where  lighter and  more
portable equipment is a necessity.  Uncontrolled  turbines used for extraction
                                  8-97

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  purposes are at least 25 percent more expensive to own than Internal combus-
  tion engines, as Figure 8-13 shows,
  8-4.2  Impact on Product Prices
         NOX standards will affect product prices primarily for electricity and
  natural gas.  However, cost Increases will  be insignificant,  even if emissions
  standards are set  at 60 percent average reductions.   The  analysis 1s explained
  below in  terms  of  20, 40, and  60 percent NOX reduction  alternatives,  Because
  there are three  kinds of engines (diesel, dual  fuel,  and  gas)  and three
  alternative  levels  (20,  40,  and  60  percent)  for emissions  standards, the
  number  of possible  options for standards would be too large to cover in a
  readily comprehended  manner.  To simplify the presentation, this  analysis
  considers across-the-board standards for all the fuels together.
  8.4.2.1  Cost Pass-Through
        When the demand for a manufacturer's  goods is inelastic (i.e., In-
  sensitive  to price  changes),  added costs are likely to be  transferred to  the
 consumer.   This  cost pass-through occurs where the  manufacturer's product
 1s  viewed  as  a necessity by the  consumer with few,  if  any,  substitutes avail-
 able.   The extent of pass-through,  then,  depends on many factors  in addition
 to  the unique qualities  of the product  -  the  price elasticity  of demand  for
 the industry  as a whole  (determined  in  part  by other demands which are  in-
 directly related) and  the  cross-price elasticities of the products  within
 the  same industry.   It is assumed that since manufacturers produce  recipro-
 cating engines for essential applications in  specialized market, cost in-
creases would be passed through to the consumer.
       Section 8.4.1.3 demonstrated that the  internal  combustion engine
industry does  not  now face competition from gas turbines  based  on  cost factors
                                 8-99

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                                       X
  alone for either  of the  two main applications-electricity generation and
  gas  compression during production and pipeline transmission--in which NOV
  standards will cause  cost penalties.  In electric generation, it may be
  recalled, turbines  are uneconomic for baseload use and for additions to
  plants already using  banks of reciprocating engines.  In gas compression,
  gas  turbines are  not  suited to gathering applications (because of variable
  gas  flow) and are not easily added to stations already using reciprocating
  engines.
        Furthermore, the industry is  segmented into many specialized markets
 and  submarkets, as discussed in Section  8.1.3.  Most internal  combustion
 engines have carved out a niche in which they have few,  if any,  substitutes
 in the applications for which  they are used.
        At the same time,  demand  for  engines would  not likely fall  significantly
 as a  result of higher prices for engines in the  range that  the test  data  in-
 dicate would take  place.  The  increase in some localities for electric rates
 would be,  at its maximum, somewhat higher—nine percent—but is much less
 than  recent increases  from other causes, while past rate increases have not
 led to much decrease in demand for electricity (see subsection 8.4.2.2).
 Municipalities have  the option of purchasing power from larger utilities,
 but tend to  produce  the bulk of their own needs and purchase only small  amounts
 of power.   (Frequently, these utilities sell  power.)  Furthermore, consumers
 would not  consume appreciably less  gas because of a 0.4 percent increase in
 delivered  prices (see subsection 8.4.2.3).
       With little decrease  likely  for overall  engine demand and  little  compe-
tition from substitutes, manufacturers will  likely  pass through cost  increases
to consumers.
8-101

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8,4.2.2  Electricity Generation
       Reciprocating Internal  combustion engines are used to generate elec-
tricity on a continuous (baseload) basis for small  municipalities.  They
account for only a small fraction of total electricity generation In the United
States.  There were 936 Internal combustion plants  (excluding gas turbines) at
year-end 1975,(84)  These had  a total generating capacity of 5,021 megawatts-
equal  to one  percent of the total U.S.  electric generating  capacity  of  505,772
megawatts.(85)   Therefore, the Impact on  electricity prices  is best  measured
 1n two dimensions-local  and weighted national  impacts.
        Although localities deriving  all of their electricity from internal
 combustion are rare,  and  the  chances of all  of those  engines being  subject
 to NSPS are remote at least  in the near future, an evaluation  of this case
 was done to provide the maximum possible increase  in electricity prices
 which could be experienced by any consumer.  Based on a sample of ten utili-
 ties  using internal combustion engines to generate at least 90 percent of
 their electricity sales, engine costs  (engine price, maintenance, and  fuel
 expenses)  typically account for  half the costs of  delivered electricity to
 consumers.(86)   Electricity distribution and  general overhead costs account
  for the  remainder and would  be unaffected by  NOX  standards.  Therefore, an
  engine penalty from NOX  standards would be halved when  applied  to  the  price
  that consumers pay for electricity  in  these localities.  Table  8-24 shows
  the inflationary impact on  local electricity prices for various emissions
  standards.
         The maximum impact is nine percent and takes place in the case of
  diesel engines at a  60 percent alternative (based on data from only one
   model).   Recent  sales of diesel and dual fuel engines  to  the electric
                                    8-102

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     TABLE 8-24.  MAXIMUM INFLATIONARY IMPACT ON LOCAL ELECTRICITY PRICES
Engine type
Diesel
Dual Fuel
Alternative NOX
Reductions
20% 40* 60*
3* 3* 9*
2% 3% 3%
  generation market Indicated  that  new  sales were running approximately 50
  percent dlesel  and  50  percent dual fuel.

         In  comparison,  electric rates  have Increased far more than other
  factors.   Since  1970 residential, commercial, and Industrial electric rates
  have risen  by five percent to 30 percent annually.  This 1s shown 1n Table
  8-25.
         TABLE 8-25.  ^STORICAL^PERSPECTIVE ON ANNUAL  INCREASES  IN
    Period
   •MMMMMMM
 1970 to 1971

 1971  to 1972

 1972  to 1973

 1973  to 1974

 1974  to 1975

 1975  to  1976

    Range
Residential
500 kWh
H 6.2*
'2 7.6*
'3 4.6*
'4 12.4*
5 27.3*
6 7.2*
Commercial —30, kW,
6,000 kWh
5.5*
7.3*
4.9*
11.1*
24.8*
6.3%
                                      Industr1al«300 kW,
                                          60,000 kWh
                                             •MMBMMM
                                             7.6*

                                             8.5*

                                             5.7*

                                            15.6*

                                            30.6*

                                             6.5*
4.6*-27.3*
4.9*-24.8*
                                                           5.7*-30.6*
SOURCE.:  Federal  Power Commission,  Typical  Electric  Bills.  1976.
                                 8-103

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       Because internal  combustion engines  account  for just  a  small  fraction
of all electricity generated nationwide (with the national electric  bill  from
private utilities alone valued at $44.4 billion in  1976),(87)  the NOX emis-
sions standards on new source reciprocating internal  combustion engines would
raise the national electric bill by just a fraction of a percent.  If the
standards had been fully implemented in 1976, the inflationary inpact on the
national electric bill would have been just 0.1 percent in the case of 20 or
40 percent alternatives and 0.3 percent in the case of a 60 percent alterna-
tive.  This  is  shown  in Table 8-26.
          TABLE  8-26.  MAXIMUM  INFLATIONARY  IMPACT ON THE NATIONAL
                      ELECTRIC BILL WITH  FULL  PHASE-IN
Impact
Increase
Alternative NOX
Reductions
20% 40%
0.1
60%
% 0.1% 0.3%
        In actuality, new source performance standards are phased-in only
 gradually.  Penalties are not incurred until new controlled engines are
 purchased, while old uncontrolled engines are retired from service after a
 30-year  lifetime.  Assuming new sales equal to three percent of the existing
 engine population and retirements also equal to three percent  (in effect, a
 steady population as indicated by recent sales data), after five years,
 approximately 15 percent  of all engines will be controlled and will incur
 penalties.   The inflationary  impact  of the  standards  at  that time  is  shown
  in Table 8-27.  It  ranges from 0.02  percent for a  20 percent standard to
  0.04 percent for a  60  percent standard.
                                    8-104

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           TABLE 8-27.   INFLATIONARY IMPACT  ON  THE  NATIONAL  ELECTRIC
                        BILL,  AFTER FIVE  YEARS
Impact
Increase
Al
20%
0.02%
ternative NOX
Reductions
40% 60%
0.02% 0.04%
 8-4.2.3  Gas Production and Transmission
        Reciprocating internal combustion engines are used to transport most
 of the gas consumed in the United States.  Internal combustion engine costs
 account for only six percent of the delivered price of gas ($1.60 per Mcf in
       (88)
 1976),     though the percentage is somewhat higher for areas distant from
 producing states.  The average cost penalties for gas  engines (which account
 for nearly all  recent sales to the  reciprocating pipeline engine market)
 ranged from two percent at a  20 percent  alternative to  six  percent  at a
 60 percent  alternative.  Table 8-28 shows the impact of these penalties on
 delivered gas prices.
         TABLE 8-28.   INFLATIONARY IMPACT ON DELIVERED GAS PRICES
                       AFTER FULL PHASE-IN
Impact
Increase

Al
20%
0.
1 V
\ 7o
ternative NO
Reductions
40%
0.3%
X

60%

0.
4%
       The largest inflationary impact,  at a 60 percent alternative,  would
involve a price increase of just 0.4 percent.   (This  was calculated as  if
                                 8-105

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all engines 1n use 1n 1976 had been controlled  and  Incurred  penalties.)   By
comparison, the national  average delivered price of gas  has  risen  by 103  per-
                                                                          (89)
cent 1n recent years-from $.79 per Mcf 1n 1973 to  $1.60 per Mcf 1n  1976--
from other causes,
       The Increase 1n gas prices would not reach the above  levels until  all
engines were controlled.   With sales and retirement rates equal  to those  1n
the electric generation market (I.e., three percent annually), 1n five years
controls would cover 15 percent of all engines,  The Inflationary Impact
at that time would be a 0.06 percent Increase 1n the case of the most stringent
standard  (60 percent).  This 1s shown 1n Table 8-29.
          TABLE 8-29.   INFLATIONARY  IMPACT ON DELIVERED GAS PRICES,
                       AFTER  FIVE YEARS
Impact
Increase
Alternative NOX
Reductions
20% 40% 60%
0.02% 0,04% 0.06%
 8.4.2.4  Impacts Over Five Years
        Users of Internal  combustion engines will  have to lay out additional
 capital expenditures to purchase more expensive engines (the engine purchase
 price component of the cost penalty from NOX controls).  In the case of In-
 ternal combustion engines, however, the capital cost penalty 1s small.   Most
 of the penalty comes from higher fuel or maintenance costs.  A two percent
 engine price penalty can be expected on average for all alternative
                                   8-106

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   standards.^  with annual Industry domestic non-standby Internal  combustion
   engine sales of $96 million (projected to remain roughly constant),  the
   additional capital cost for users would equal  $1.9 million  per year  -- a
   total of $9.6 million on a cumulative  basis  over the  first  five years.
         Total costs 1n the fifth year (Including amortized capital  costs,
  maintenance costs, and fuel costs) would range  from $16 million for a 20  per-
  cent alternative to $26 million for 40  percent  and $45 million  for 60 percent.
         In dollar terms, the Impact of the standards 1s shown 1n Table 8-30
  for all markets 1n the fifth year after the standards  are Implemented.
             TABLE  8-30.   COSTS OF  VARIOUS ALTERNATIVE STANDARDS  IN
                          THE  FIFTH YEAR  (IN MILLION DOLLARS)

                .   ,.    .                 Alternative NOX Reductions
                Application                  20%     401      60%
          Gas Production & Trans-
          mission                            5.9     13.6     17.8
          Electric  Generation                7.9      8.9     19.9
          Other Applications                 2.2      3.4      7.1

           All Applications               16.0     25.9     44.8
12/
-^Two percent reflects  a one percent  increase  from  pass-through of test costs
   and an average of one percent increase  for use  of manifold  temperature
   reduction in some cases.   (Manifold temperatures  reduction  would incur  a
   price increase of two percent where used, but would  probably be used less
   frequently than  other techniques.)
                                  8-107

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8.4,3  Impact on Employment
       Since NO  standards will  not cause  significant  changes  in manufac-
               A
turers' sales if retard, manifold temperature  reduction,  and  air-to-
fuel changes only are used, they will  not  cause significant impacts on
employment.
       Nationally, sales shifts among manufacturers will  tend to  balance out
with no decrease in aggregate sales or employment in the industry.  As  noted
in Section 8.4.4 (below), exports and imports of internal combustion  engines
will not likely experience any changes because of NOX standards on engines
used in the  U.S.  Therefore, few jobs would be lost to foreign firms.  More-
over,  because  sales changes of greater than 10 percent are not expected
 (and most  would be much  less), the extent of  local shifts will also be minor.
 8.4.4   Impact  on  Foreign Trade
        The foreign trade balance will not be  significantly affected by NOX
 standards.  The amount of imported engines  is not  expected to change.  Most
 internal  combustion  engine imports have been  engines  that  are smaller than
 the minimum size to  be controlled by  the  proposed  standards.  Department  of
 Commerce data showed that the average value of imported  diesel engines  in 1973
 was $889 per unit.(90)  This is far below the likely  cost  for a  diesel  engine
 of the size that would be controlled by the proposed  new source  performance
 standards since a typical 1,000 horsepower diesel  engine would cost  about
 $150,000.   In addition,  imported engines  would have to meet NOX emissions
 standards.  Because foreign firms would have smaller U.S.  sales volumes over
 which to  spread capital  test requirements for NOX reductions, the NOX stand-
 ards  would  actually tend to create a barrier to imports.
        Proposed NOX standards do  not apply to engine exports.  Control tech-
  niques like retard, air-to-fuel changes, manifold temperature reduction, and
                                    8-108

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 derate  do  not  Involve  changes  in mass production items.  There would be no
 loss  in scale  economies to manufacturers if they had to produce controlled
 engines for  domestic sales and uncontrolled engines for export sales.  More-
 over, even techniques  like combustion chamber modification and exhaust gas
 recirculation  would have little impact on exports, because of the specialty
 nature  of the  large engine industry, where even without controls, each
 engine  is typically tailored to a specific customer's needs rather than Just
 mass produced.
        Fuel imports would be increased marginally by the fuel  penalties
 involved in meeting NOX standards.   In the fifth year after standards take
 effect, 15 percent of all  engines will  be controlled.   The  additional  fuel
 requirement (to be met by additional  imports  of oil)  in that year would be
 1.0 million barrels of oil  for a  20 percent alternative, 1.5 million barrels
for 40 percent, or 2.4 million barrels  for  60  percent.   This 1s shown  in
Table 8-31.
           TABU' 8-31.   ADDITIONAL  FUEL  NEEDS,  IN THE  FIFTH YEAR
                        (MILLION  BARRELS)
Engine
Type
Gas
Diesel
Dual Fuel
Alternative
20%
0.6
0.3
0.1
NOX Reductions
40% 60%
1.0 1.0
0.4 1.4
0.2 0.1
                 All Engines         1.0       1.5       2.4
                                 8-109

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                                                                 (91)
       Measured against  1976 oil Imports of 2,850 million barrels/" the
Increase 1n oil  Imports  would  be 0.04 percent for a 20 percent alternative,
0.05 percent for 40 percent, and 0,09 percent for 60 percent.  Measured
against 1976 Imports of  all goods  and services of $160 billion and valued at
an average of $12.10 per barrel/92' the Increase 1n U.S. Imports would be
0.008 percent for a 20 percent alternative 0.011 percent for 40 percent, and
0.018 percent for 60 percent.
8.4.5  Summary of Economic Impact  Analysis
       With minor exceptions,  there  appears to be little difference  among
the Impacts of a 60 percent, 40 percent, or 20 percent alternative.  This
1s a qualified judgment  based  on the assumption  that derating, exhaust gas
redrculatlon, or combustion chamber modification will not  be necessary 1n
order to meet these alternatives.
       Although aggregate price Impacts  on  consumers vary directly with the
level of control, even a 60 percent alternative  would  raise gas  and  elec-
tricity prices less than half  a percent.   On  the local level, however,  1t
1s theoretically possible for  a locality entirely dependent on new reciprocat-
ing  Internal combustion engines for generating  Its  electricity to experience
a nine  percent Increase 1n electricity prices at the 60  percent  alternative.
This  1s three  times more than the Increases for the 40 or  20 percent alter-
native.   Such  localities, however, would represent an  extremely  small  part
of  the  overall population.
        Manufacturers  would face only limited Impacts.   Capital  test  require-
ments would be within their ability to finance  Internally from profits,
while the costs  could be  recovered through a one percent average price
 Increase  over a  five-year period.   Despite variations 1n cost penalties, no
                                  8-110

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 ffrm 1s Hkely to lose  more than  five  to  six  percent of  Us sales  (In all of
 their markets).   Gas  turbines may make Inroads  Into certain manufacturers'
 sales for dlesel  engines  only at  a 40  or  60 percent alternative, but their
 cost advantage in the normal operating  range  of 6,000 to 8,000 hours per
 year would be  slight.   Employment, like sales, would experience little
 change.   Imports  and exports of internal combustion engines would also face
 little  change.  Oil imports would increase by only a fraction of a percent.
        Several additional points can be noted.  In summary, the full impact
 of the  standards would not be markedly different for the 20,  40 and 60
 percent alternatives.   Second,  based on conservative analytic  techniques,
 the only possible impact of notable  magnitude  would be  the  rise in electric
 prices for isolated localities  using all internal  combustion engines.  Third,
 full  attainment of the impacts  on  users will not be realized until  all engines
are replaced by controlled engines incurring penalties  -- a process  that  will
take  30 years to complete.
                                8-111

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                          REFERENCES FOR CHAPTER 8
(1)   Diesel and Gas Turbine Worldwide Catalog.  Diesel and Gas Turbine
Progress.  Volume 39.  1974.
(2)   Current Industrial Reports, Internal Combustion Engines.  U.S.
Department of Commerce, Bureau of the Census, Washington, D.C.  MA-35L.
1968, 1970, 1972, 1973, 1974, 1975.
(3)   Shipments of Internal Combustion Engines,  1958-1967.  U.S. Department
of Commerce, Business and Defense Services Administration.  Washington,
D.C.  1969.
(4)   Hare, C. T. and K. J. Springer.  Exhaust Emissions  from  Uncontrolled
and Related Equipment Using  Internal Combustion Engines,  Part 5 -
Heavy-Duty Farm, Construction,  and  Industrial Engines.   Southwest  Research
Institute, San Antonio, Texas.  AR-898.  October  1973.
(5)  Op. Cit., Reference  2.
(6)  Op. Cit., Reference  3.
(7)  16th  Annual Pipeline Installation  and  Equipment  Costs.   Oil  and Gas
Journal,   p. 81.  August  13,  1973.
(8)  McGowin,  C. R.  Stationary Internal Combustion  Engines  in the United
States.   Environmental  Protection  Agency.   EPA-R2-73-210.  April  1973.
(9)  The  Fortune Listing  of  the 500 Largest  U.S.  Industrial  Corporations,
Fortune,  May 1977.
(10)   Ibid.
(11)   Norton,  G. S.   (Acurex) and  A.  L. Foltz,  Jr.   (Enterprise Engine
Division,  DeLaval  Turbine).   Private Communication.   July 29, 1974.
(12)   Offen, G.  R.,   (Acurex) and  R.  D. Henderson,  et al.  (Caterpillar
Tractor Company).   Private Communication (Memorandum to supplement Trip
Report dated August  30, 1974).   March 21,  1975.
 (13)   Offen, G.  R.   (Acurex) and C. T.  Ahlers,  et al.  (Cummins Engine
Co.)   Private  Communication (Memorandum to supplement Trip Report dated
August 30, 1974).   August 30, 1974.
 (14)   Offen,  G.  R.   (Acurex) and F. Schaub (Cooper-Bessemer  Co.).   Private
Communication.  October 13, 1975.
                                    8-112

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 (15)  Goodwin, D. R.  (EPA/Emission Standards  and Engineering  Division)
 Request for Information.  June 16, 1976.

 (16)  Snyder, W. E.  (Waukesha) and D. R. Goodwin (EPA).  Private
 Communication.  July 20, 1976.

 (17)  Thompson, M. P. (Superior) and D. R. Goodwin (EPA).  Private
 Communication.  August 3, 1976.

 (18)  Hanley, G. P. (CMC) and D. R. Goodwin (EPA).  Private
 Communication.  September 7, 1976.

 (19)  Greiner, S. D. (Cooper) and D.  R. Goodwin (EPA).  Private
 Communication.  August 4, 1976.

 (20)  Newton,  C. L. (Colt)  and D.  R.  Goodwin (EPA).   Private
 Communication.  August 2, 1976.

 (21)  Fleischer, A. R.  (DeLaval)  and  D. R. Goodwin (EPA).  Private
 Communication.  July 30,  1976.


 (22)  1974 Report on Diesel  and Gas Engines Power Costs.  The American
 Society of Mechanical  Engineers.   March 25,  1974.
 i«3)«S!?nn9ei'  F:  ?;MB19 D1esels  for Power Plants.   Power Engineering.
 pp.  Jo-40.   March  1968.

 (24)   1973  Year End  Summary of the Electric Power Situation in the United
 December  II   1973        SUrVey Committee'  Ed1son Electric Institute.

 (25)   Federal Power  Commission Bureau of Power  Staff Report.   Proposed

                                                '•  1977-   oocket R-362-
                   9^
 (27)  Youngblood, S. B.  (Acurex)  and  J.  Blasingame  (Bechtel).   Private
 Communication.  December 6, 1974.

 (28)  Op. Clt., Reference 17.

 (29)  Power,  p. S-3.  November 1974.

 (30)  Ibid.

 (31)  Op. Clt., Reference 20.

(32)  Op. Clt., Reference 19.

(33)  Op. Clt., Reference 21.
                                   8-113

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(34)  Op.  C1t.,  Reference 17.
(35)  Op.  Cit.,  Reference 2.
(36)  Op.  C1t.,  Reference 3.
(37)  Op.  Cit.,  Reference 20.
(38)  Op.  C1t.,  Reference 19.
(39)  Op.  Cit.,  Reference 21.
(40)  Sheppard,  R. W. (Ingersoll-Rand) and D. R. Goodwin (EPA).  Private
Communication.  July 28, 1976.
(41)  Op.  Cit.,  Reference 16.
(42)  Op.  Cit.,  Reference 17.
(43)  Annual Pipeline Installation and Equipment Costs.  Oil and Gas
Journal.  Pipeline Economics Issue.  1960-1977.
(44)  18th Annual Pipeline Installation and Equipment Costs.  Oil and Gas
Journal,  p. 70.  August 18, 1975.
(45)  FPC Pipeline Backlog up Over $2 Billion.  Oil and Gas Journal,  p.
115.  September 23, 1974.
(46)  Youngblood, S. B.  (Acurex)  and R. Dubner  (Standard Oil, Richmond,
California).  December 6, 1974.
(47)  Offen, G. R. (Acurex) and J. D. Martin  (Union Carbide Corporation,
Port Lavaca, Texas).  Private Communication.  December  11, 1974.
(48)  U.S. Bureau of the Census,  U.S. Exports - Schedule B - Commodity  by
Country.  Report  FT410.  December 1969-1973.
(49)  U.S. Bureau of the Census,  U.S. Imports for  Consumption  and General
Imports,  TSUSA  Commodity and  Country.  Report FT246.   1969-1973.
(50)  Op. Cit., Reference 4.
(51)  Norton, G.  (Acurex) and Thermo-King Sales and  Services Company.   San
Leandro,  California.  Private Communication.  October  16,  1974.
(52)  Reyl,  G., Deutz Diesel  Engines  Operating  1n  Underground  Mines.
Klockener-Humboldt-Dentz AG.  Cologne, Germany. Diesel and Gas  Turbine
Worldwide Catalog, Vol.  41, 1976.
 (53)  Youngblood, S. B.  (Acurex)  and  J. Garrity (General  Electric).
Private Communication.   March 1975.
                                    8-114

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  (56)  Henderson,  R.  D.  (Caterpillar) and R.  0.  Selffert
  Private Caimun1cat1on.  December 19, 1974?     M1"«rt

  (57)  Op.  Clt., Reference 55.


                           St't1on Costs'  «'  "x1 Sas Journal,  p.  89.


 o!!'i/ou!l5b'<)0dl Sl B> (teurix)  and Mr.  Schjffersman (Natural
                             1976?' 8>
                                ' Se"iUb (Co^er-B»»~^ «••).  Private
                         ^^^
["I  E?S)?1rSov,J;b^r {9T!'l9^?  Co"tt™"1 *tori>.  Letter to  D. Goodwin
                                 8-115

-------
(54)  Youngblood, S. B.  (Acurex) and A. Underman (Northwestern Public
Service, Huron, South Dakota).  March 24, 1975.

(55)  Youngblood, S. B.  (Acurex) and A. L. Foltz, Jr. (Enterprise
Engines).  Private Communication.  January 15, 1975.

(56)  Henderson, R. D. (Caterpillar) and R. D. Selffert (EPA/ISB).
Private Communlcation.  December 19, 1974.

(57)  Op. C1t., Reference 55.

(58)  Completed Compressor Station Costs.  011 and Gas Journal, p. 89.
August 23, 1976.

(59)  Youngblood, S. B. (Acurex) and Mr. Schaffersman (Natural Gas
Pipeline Company of America, Chicago,  Illinois).  Private Communication.
October 4, 1977.

(60)  Schaub,  F. S.  (Cooper)  and S. B. Youngblood (Acurex).   Private
Communication.  February 23,  1976.

(61)  Newton,  C. L.  (Colt) and  S. B. Youngblood  (Acurex).   Private
Communication.  February 18,  1976.

(62)  Fletcher,  J.  S.  (Acurex)  and  C.  Newton  (Colt  Industries).   Private
Communication.   November 3,  1975.

(63)  Offen,  G.  R.  (Acurex)  and F.  Schaub  (Cooper-Bessemer  Co.).   Private
Communication.   October  13,  1975.

(64)  McGowIn,  C.  R.   Stationary Internal  Combustion Engines 1n  the  United
States.   Environmental  Protection Agency.   EPA-R2-73-210.   pp.  73-77.
April  1973.

(65)   Anderson,  H.  C.,  et  al.  A New Family of Catalysts for Nitric  Add
Tall  Gases.   Engelhard  Industries Technical  Bulletin. Vol.  VII.  No.
3:100-105.   December 1966.

(66)   Shreve, R.  N.  Nitrogen Industries.   In:  Chemical Process
Industries.   McGraw-Hill,   pp.  302-313.   1967.

 (67)   Requelro,  J.  F. (Teledyne Continental Motors).  Letter to D. Goodwin
 (U.S.  EPA).   November 19,  1974.

 (68)   Shaw,  J. C.   Emission Reduction Study on a Carbureted Natural
Gas-Fueled Industrial Engine.  Draft ASME Paper.  White Superior
Division.  White Motor Corporation.  November 1974.

 (69)   Storment, J. 0. and K. J. Springer.  Assessment of Control
 Techniques for Reducing Emissions from Locomotive Engines.  Southwest
 Research Institute.  AR-884.  April 1973.
                                    8-115

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(89)  Ibid.

(90)  U.S. Bureau of Census, U.S.  Imports for Consumption  and  General
Imports, TSUSA Commodity and Country.  Report FT246.   1973.
    4.uUAS* JfiPartment °f Commerce, U.S. International Transactions:
Fourth Quarter and Year 1976, Survey of Current Business,  p. 41.  March
Ly// .

(92)  Ibid.
                                 8-117

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                             9.  RATIONALE
  9.1   SELECTION OF SOURCE FOR CONTROL
       Previous investigators have concluded that stationary internal
  combustion  (1C)  engines  are major contributors  to nationwide emis-
        (1>2,3)
  sions.   '  '     In particular, stattonary 1C  engines  are sources  of NO ,
                                                                       /\
  hydrocarbons  (HC),  particulates,  sulfur  dioxide  (SOJ,  and  carbon
                                                    ^
  monoxide (CO)  emissions.  NOX emissions  from  1C  engines,  however,  are
  of more concern  than emissions of  these  other pollutants  for two rea-
  sons.  First,  NOX is the primary pollutant emitted by stationary engines
  Second, EPA has  assigned a  high priority to the development  of standards
  of performance limiting NOX emissions.  Assuming existing levels of
 emission controls, national  NOX emissions from stationary sources are
 projected to increase by more than 40 percent in the 1975-to-1990
 period.   Applying best technology to all  sources would reduce this
 increase but would not prevent it from occurring.   This  unavoidable
 increase in  NOX emissions is attributable largely to  the fact that
 current  NOX  emission control techniques are based  on  combustion  rede-
 sign.   In addition,  few NOX  emission  control  techniques  can  achieve
 large  (i.e.,  in the  range of 90 percent)  reductions  in N0¥ emissions.
                                                          A
 Consequently,  EPA has assigned a  high  priority to  the development of
 standards of performance  for major  NOX  emission sources  wherever signifi-
 cant reductions in NOX can be  achieved.  Studies have shown  that 1C
 engines are significant contributors to total U.S. NOX emissions from
 stationary sources.  Figure  9-1(4) shows that internal combustion
engines account for 16.4 percent of all stationary source NOV emissions,
                                                            /\

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Industrial  Process Combustion 1.6%
             Noncombustion 1.7%
       Warm Air Furnaces 2.8%
        Gas Turbines  3.0%
        Fugitive 4.4%
Incineration 0.4%
                                                     Utility Boilers
                                                          49.0%
                         Packaged Boilers
                              20.7%
    Figure 9-1.   Distribution  of  stationary  NOX emissions  for the year  1974
                 (Reference  4).
                                      9-2

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  exceeded only by utility and  packaged boilers.
      An inventory of emissions from installed stationary engines was
  computed based  on the information presented in summary form in  Table 9-
  1.     As a group, stationary 1C engines (based  on  1975 data) currently
  account for 3 to 9 percent of the NOX> carbon monoxide (CO), and hydro-
  carbons (HC) emitted from all sources, and 9 to  14  percent  of those
  emitted from stationary  sources.   This table also shows the percentage
  contribution to nationwide totals  from installed engines  as a function
  of their size and  the type of fuel they consume.  Table 9-2(6) shows
  the emission factors used to  generate Table  9-1.   Annual  production
 rates are estimated  in Table  9-1 to indicate the potential number of
 sources  that could be affected by New Source Performance Standards
 (NSPS).
     Table 9-3(7> presents a clearer picture of the  relationship between
 the number of potentially controllable  sources and their contributions
 to the nationwide inventory from currently installed units.* This
 table also shows that numerous small engines  (nearly 13 million units
 of 1- to 100-hp) are  the  most significant contributors of  HC and CO
 emissions from 1C engines.  (Note that nearly 80 percent of  the HC
 emissions from engines smaller than 350 CID/cyl are methane, a noncri-
 teria pollutant.) Therefore,  it can be concluded that NOX emissions
constitute the most significant pollutant  emitted  by  stationary  engines
since three-quarters of these emissions  are emitted by  large-bore
(greater than 350 CID/cyl) engines.
        Ln^n^MM 'fTl! r?w of 6m1ss1on estimates for engines
       than  350-cub1c-1nch displacement per cylinder (CID/cyl).  As is
               w--wAwa^
                              9-3

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        TABLE 9-1.  NATIONWIDE EMISSIONS FROM INSTALLED 1C ENGINES
                    (Percent of Total  Emitted 1n U.S.  Each Year)
Fuel
Diesel

Natural Gas
Dual-Fuel
Gasoline

hp Range
20 - 100
101 - 500
>500
Subtotal
<500
>500
Subtotal

<15
15 - 99
>100
Subtotal
Total
Annual
Production,
Unitsb
39,000
14,000
3,400
56,400
5,400
600
6,000
Included 1n Diesel
12,600,000C
85,000
10,000
12,600,000
+ 95,000
12,600,000
+ 157,400
Percent All Sources
Percent Stationary Sources
In Mass Units (10s metric tons/yr)
NOX
0.36
0.55
0.48
1.39
1.93
4.16
6.10
0.28
0.16
0.31
0.11
0.58
8.4
13.7
2.0
CO
0.029
0.45
0.016
0.09
0.107
0.229
0.336
0.02
1.84
0.81
0.31
2.96
3.4
11.0
3.6
HCT
0.062
0.095
0.033
0.19
0.81
1.73
2.54
0.11
0.56
0.29
0.10
0.95
3.8
8.8
0.9
aTotal U.S. emission from EPA Nationwide A1r Pollutant Inventory for

bBased on estimates of average hp of engines used 1n each application

^Includes all engines 1n this size category (mobile and stationary).
 Listed separately 1n the totals because of the unique nature of
 this group
                                  9-4

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 TABLE 9-2.  EMISSIONS FACTORS FOR INVENTORY ON TABLE 1 ,a g/hp-hr
             (Reference 6)
Fuel
Gasoline >15 hp
<15 hp
Diesel >500 hpb
<500 hpc
Natural gas
Dual-Fuel
NOX
8,85
5,63
12,9
12,4
11,5
8,2
CO
102
295
1,8
4.47
2,81
2.0
HCT
8.38
20.5
0.43
2.12
4.86
3.1
Emission factors for gasoline and diesel engines are modal
 averages; those for natural gas and dual-fuel are for
 rated conditions.
bBased on an average of rated condition levels from engines
 considered
°We1ghted average of two- and four-stroke engines,   Weighting
 factors • 2/3 for four-stroke and 1/3 for two-stroke
                       9-5

-------An error occurred while trying to OCR this image.

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        Other studies  have  investigated  the  emissions  of various  sta-
   tionary  sources  to  aid in  establishing  a  priority for setting  standards
   of  performance.   For example,  the Research Corporation of New  England
   determined  the effect that standards  of performance would have on
   nationwide  emissions of particulates, NOX, SOX, HC, and CO from sta-
   tionary sources.(8)  As per EPA-450/3-78-019, "Priorities for New
  Source Performance Standards under the Clean Air Act Amendments of
  1977," sources were ranked according to the impact,  in tons  per year,
  that standards promulgated in  1980 would have on emissions  in 1990.
  This ranking placed  spark  ignition 1C  engines second and  compression
  ignition  1C engines  third  on a  list  of 32  stationary N0¥  emission
                                                         /\
  sources.   Consequently, stationary 1C  engines  have been selected for
  development  of standards of performance.
       In a  subsequent study, Argonne National Laboratory used  the re-
  sults of the TRC  study to develop a priority listing for setting NSPS.(9)
  In developing this list, source screening factors were used to aid in
 establishing these control  priorities.   Factors considered were:
      •    Type, cost, and  availability of control technology
      •    Emission measurement  methods  and  applicability
      •    Enforceability of regulations
      •    Source location and typical source  size
      •    Energy impact
      •    Impact on scarce  resources
      •    Other environmental media constraints
The study found that even with the application of maximum NSPS control
efforts, a significant increase  of more than 40 percent in  NOX emissions
                                                             x
                                   9-7

-------
occurs in the 1975-to-1990 period,   Furthermore, the study concluded
that the control of Internal combustion engines emissions is a matter
of high priority.
     Other factors favoring the control of 1C engines are summarized
briefly below:
     t    Control techniques for NOX emissions  have been shown to be
          effective and applicable to  installed 1C engines,  These
          techniques can  reduce NOX emissions from 40 to 60  percent on
          the average  (see  Section 4.0).
     •    No  federal,  state or  local NOX  standards exist  (with  the
          exception of Los  Angeles and Chicago).  Therefore, since
          engines  are  manufactured for a  variety  of  dispersed  appli-
          cations,  a  single national  standard  is  preferable.
      •    1C engines  compete  with  gas  turbines  in certain  applications.
           Since NSPS  are currently being  developed  for  gas turbines,
           the absence of standards for 1C engines may result in a shift
           away from gas turbines to  1C engines.  This could cause
           greater NOX emissions from both sources than if no standard
           were applied to gas turbines, since  1C engines emit NOX at
           greater rates  than gas turbines.
      Furthermore, as  shown in Section  3.0, sales of large-bore engines,
  primarily for  oil and  gas  exploration, have been substantial during the
  past five years, and  are anticipated  to  continue and possibly  increase.
  Stationary  1C  engines,  therefore, are significant contributors  to  total
  nationwide  emissions  of  NOX.   Consequently, based on all  these  factors,
  stationary  1C  engines have been selected for  development  of standards
  of performance.
                                     9-8

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   9.2   SELECTION  OF  POLLUTANTS
   Oxides  Of Nitrogen
        Stationary engines emit the  following pollutants:  NOX, CO, HC,
   partlculates, and SOX<  As Table  9-3 Indicates, the primary pollutant
   emitted by stationary engines 1s  NOX, accounting for over six percent
   (or 16 percent of all stationary  sources) of the total U.S.  Inventory
  of NOX emissions.   This table also Illustrates that large-bore engines
  emitted three-fourths of these  NOX emissions.   It  will be  shown in
  Section 4.0  that the control  technology exists to  effectively  reduce
  NOX  emissions  from  large-bore engines.   Furthermore, N0¥ emissions  are
                                                         rt
  projected  to  Increase despite promulgation  of  all  possible New  Source
  Performance Standards.  Therefore,  NOX  emissions from  stationary  en-
  gines  have been  selected for control by means  of NSPS.
  Hydrocarbons and Carbon Monoxide
      Table 9-3 also shows that stationary 1C engines emit substantial
 quantities of CO and HC as well.   Numerous small (1-100 hp)  spark Ignition
 engines, which are similar to automotive engines,  account for about  20
 percent of the uncontrolled HC  emissions and about  80  percent of the
 uncontrolled  CO emissions.   However, as  mentioned  in Section  9.3,  the
 large  annual  production of  these  small spark Ignition engines  (approxi-
 mately  12.7 million)  makes  enforcement of  a  new source  performance
 standard  for this group difficult.
     An additional factor 1n considering CO and  HC control 1s that
 Inherent engine characteristics result in a trade-off oetween NO
control and control  of CO and HC.   A detailed discussion of the trade-
off can be found 1n Section 9.4.   In some cases, particularly naturally
                                   9-9

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aspirated gas engines,  the application of NOX emission control  tech-
niques could cause increases in CO and HC emissions.  This increase in
CO and HC emissions is strictly a function of the engine operating
position relative to stoichiometric conditions, not the NOX control
technique.  Any increase  in CO and HC emissions, however, represents  an
increase  in unburned fuel  and hence a loss  in efficiency.  Since  1C
engine manufacturers compete with one another on the  basis of  engine
operating  costs,  which  is primarily a function  of  engine  operating
efficiency,  the marketplace will  effectively ensure that  CO  and HC
 emissions are as  low as possible following the application  of NOX
 control  techniques.   In addition, promulgation of CO and HC emissions
 standards of performance could, in effect, preclude significant NOX
 control.  CO emissions, which are primarily a function of oxygen  avail-
 ability and only secondarily of temperature, show  a pronounced rise  as
 the mixture becomes richer than  stoichiometric, but  little variation as
 it becomes  leaner.  Carbureted  engines,  however,  which are beset by
 large variations in cylinder-to-cylinder air-to-fuel  ratios,  must
 operate near the stoichiometric ratio  to ensure that no  individual
  cylinder receives a charge which is  too lean to ignite (i.e., exceeds
  the lean misfire limit).  Consequently, increasing the air-to-fuel
  ratio to near stoichiometric to reduce the CO emissions increase has
  the effect of also limiting the NOX emissions reduction.
       These and  other  factors discussed  in Section 9.3 led to  the recom-
  mendation of  a  NOX NSPS for large-bore  engines but  not  for HC and CO
                   A
  emissions  since:
                                      9-10

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       •    The 1C engines which emit significant quantities of NO  are,
            with  some exceptions,  low emitters  of HC  and  CO
       •    Many  of the  NOX  reduction techniques  discussed  In  Section  4.4
            cause  little or  no  Increase  In  the  already  low  HC  and  CO
            emissions  rates  from most  large-bore  engines
      •     Individual engines can cause violation of the National Am-
           bient Air Quality Standards for HC only under worst-case
           atmospheric conditions, and then only very close to the
           source (less  than 0.3 km)
      •    No controls for HC used in conjunction with  NO,  controls  have
           been demonstrated which reduce  the already low nonmethane HC
           emissions  from  large-bore  engines
Particulate
     No standards of performance  are  recommended for either particulate
emissions or visible emissions (plume opacity).  This recommendation
stems from the following considerations:
     •    Virtually no data are available  on  particulate  emission  rates
          from stationary  engines  because  it  is so  difficult,  expensive,
          and time-consuming to measure  particulates, especially when
          done  in  strict compliance with EPA Method 5 sampling  tech-
          niques
    •     It would be very expensive to enforce a standard on required
         measurements for particulates in  compliance  testing which
         would be in accordance with  EPA Method 5
    •    It is believed  that particulate emission from  stationary
         engines  are  relatively unimportant because the plumes  from
        most of  these engines are not now  visible
                               9-11

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     Sulfur oxides (SO.)  emissions are strictly dependent upon the
                      A
sulfur contained In the fuel,   Thus, annual  sulfur oxide emissions from
an engine depend on the percent sulfur 1n the fuel and the fuel consump-
tion of the engine during that year,  Most engines burn low-sulfur
fuels and will continue to do so since crude and residual fuels must be
treated to  remove  the  salts from the  fuels, and Inhibitors must be added
to  prevent  the vanadium  1n the fuel from corroding 1C engine  components.
Treatment  facilities  exist, but their function 1s minimal.  The primary
reason  for the  shift  away from the treatment  of crude and residual
fuels 1s  one  of economics.   In today's market, It simply costs more  to
 buy and treat the crude  and  residual  oils  than to purchase and burn  the
 distillate oils.
      The cost of flue gas desulfurlzatlon for 1C engines does not appear
 to be reasonable from an economic viewpoint.  Therefore, the only viable
 means of controlling  SO, emissions would be combustion of low-sulfur
 fuels.  If users  1n  urban or S0x-sens1t1ve areas decide  to buy new en-
 gines  and  to use  crude  or residual oil as a  fuel with  these  engines,  then
 the  local  air  pollution authorities  could Impose  fuel  restrictions on
  these  engines.   Such fuel restrictions would be  entirely Independent  of
  the standards  of performance  from both a  technological and enforcement
  viewpoint.  That 1s, the absence of federal  emission limits on  SO, would
  not prevent a local  air pollution control  district from setting such a
  standard  since the engine would not have to be changed  In order to meet
  the local standard.   Thus, standards of performance are not  recommended
  for SO  emissions.
        A
                                     9-12

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   9.3  SELECTION OF AFFECTED FACILITIES
        In  sections  1.0  and  2.0 It was  shown  that NOX  emissions  constitute
   the most  significant  pollutant  emitted  by  stationary  1C  engines,  and  that
   large-bore  (greater than  350 ciD/cyl) engines  account  for over  75 percent
   of  all NOX  emission from  stationary engines.   This  section will establish
   criteria  that define which large dlesel, dual-fuel, and natural gas
   engines (referred to as "affected facilities") are to be affected by the
  proposed standards of performance.   The objective here 1s to apply stan-
  dards  of performance to significant sourer of NOX emissions.
      Thus, the following sections will  present and explain  the criteria
  that define  affected  facilities  after  considering the  applications
  served  by  stationary engines,  the number of units produced annually, and
  the  Incremental  NOX contributed  by  the annual  production.  The following
  discussions  are  subdivided  by  the three  operational  fuel types:  dlesel.
  dual-fuel, and natural gas.  As will be  discussed  in the following para-
  graphs, this classification separates large-bore engines Into three
  relatively distinct categories of engine applications.   Initially,  large-
 bore engines  will be defined as those exceeding 350 CID/cyl.   Then, if
 necessary,  other criteria will be presented  and explained  to  define
 affected dlesel,  dual-fuel,  and natural gas  engines.
      The following  discussion  summarized  an  extensive study of  the
 applications  of  large-bore  engines.  Many of the conclusions presented
 here  are based on information concerning  engine  sales and applications
during the past five years.   This  information was voluntarily submitted
by engine manufacturers in response to Section 114 requests for informa-
                                  9-13

-------
           This information has not been cited  for particular manufac-
turers since it is considered proprietary by the manufacturers.
Affected Diesel Engines
     The primary high usage (large emissions impact), domestic appli-
cation of large-bore (i.e., greater than 350 CID/cyl) diesel engines
during the past five years has been for oil and gas exploration and
production.  These and other applications are illustrated in Figure 9-
2>(12-17)  As  this figure  shows,  the market for prime (continuous)
electric generation  and other  industrial  applications all but disappeared
after the  1973 oil embargo,  but was quickly replaced by  sales of  standby
electric units for building  services,  utilities,  and nuclear power sta-
 tions.  The rapid growth  in  the  oil and gas  production market occurred
 because diesel units are  being used on oil  drilling rigs of various
 sizes.  Sales of engines  to export applications have also grown steadily
 since 1972, and are not a major segment of the entire  sales market.
      Medium-bore (from 35 to 350 CID/cyl) as well as large-bore engines
 are  sold to oil and gas exploration,  standby service,  and other indus-
 trial applications.  Furthermore, manufacturers of medium-  and large-bore
 engines often compete for the same applications,  although,  in  general,
 medium-bore  engines have  a  cost  advantage  (lower  $/hp).  This  is  because
 the  higher  initial  costs  for  a  large-bore, heavy-duty,  continuous-service
 engine more  than offset  their lower maintenance  and fuel costs.   This
 overlap  in sizes is best illustrated in Figure  9-3 which  shows  a consi-
  derable  number of medium- and large-bore engines in the 500- to  2000-
  horsepower range.   Figure 9-4 shows  the displacement  per cylinder that
                                   9-14

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corresponds to the ranges of horsepower offered by the manufacturers
shown 1n Figure 9-3.   Table 9-4 shows the overlap for particular engine
models.
     The application with the greatest degree of overlap for medium and
large-bore dlesels 1s petroleum exploration.  Smaller (250-to 1000-hp)
medium-bore designs (e.g., Detroit Diesel, Cummins, and Caterpillar) are
used on portable drilling rigs to drill or service 2500- to 5000-foot
wells.  These  rigs are trailer-mounted or helicopter-transported; there-
fore,  small,  lightweight (approximately 4000-lb)  engines are favored.   In
addition,  multiple units are  preferred to Insure  some backup power  1n  the
event  one  engine  1s down,  ruling  out a single  unit of comparable  total
horsepower.
      Larger horsepower engines are  used  1n  groups of three  to  five  to
 provide 800 to 3000  hp for wells  ranging 1n depth from 5000 to 25,000
 feet.   On most of these rigs, engines supply mechanical  power  to operate
 the drilling  (rotary table), mud  pumps,  and hoisting equipment.  In the
 larger units  several  engines from one manufacturer's engines operate
 pumps or generator sets for auxiliary power.(18)  A relatively new
 approach  is to generate AC power, rectify some of it for drilling power
 (variable load DC motors), and use  the rest to drive AC auxiliaries.
 This  approach 1s used primarily  on  offshore platforms, although  there  is
 interest  1n  applying  it to  land-based sites despite  its higher cost.
       In  conclusion,  then,  larger land-based drilling  sites  are the  major
 areas of overlap  of  service provided by  both  large-bore and medium-bore
 manufacturers.   These applications  and  baseload  electric generation (to a
  lesser extent, since horsepower  sales are  small) have  the  most signifi-
                                   9-18

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cant NO  emissions impact because they are high usage (approximately 6000
       A
hr/yr).  However, a greater-than-350-CID/cyl  definition of affected
facilities would result in some manufacturers (e.g., Waukesha) being
subject to control technology development costs, while medium-bore en-
gines  (of same power, but more cylinders) serving Identical applications
would  not incur  these costs.  This 1s clearly undesirable since this
definition would unfairly place  some  large-bore engines in a  less com-
petitive position  than similarly sized  (by horsepower), smaller-bore
designs.
      On the  other hand,  applying the  standards  of performance to  medium-
 bore engines serving the same applications  as  large-bore  designs  would
 Increase the number of affected facilities  from about 200 to  about 2000
 units per year (based on 1976 sales  information)  but consequently further
 reduce NO  emissions.  Medium-bore sales accounted  for significant NOX
          A
 emissions in 1976 (approximately 12,500 megagrams).  It 1s estimated that
 approximately 25 percent, or about 500 of these units, in high usage
 applications accounted for most of the medium-bore NOX emissions, since
 most  of the  remainder of these  units were sold as  standby generator sets.
 Though the  potential achievable NOX  reduction  1s significant, considering
 this  large  number,  and  the  remoteness  and mobility of  petroleum  applica-
 tions, this alternative  would  create serious  enforcement difficulties.
 Additionally,  this  alternative causes  the  standard to  apply  to lower
  power engine models with fewer number of cylinders competing in  different
  stationary markets with other unregulated  engines.  Consequently, a
  definition is required that distinguishes  between  large-bore engines that
  compete with medium-bore high  power engines used for baseload electrical
                                     9-20

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   generation from large-bore engines that compete solely with other large-
   bore engines.
        One approach would be to define dlesel  engines covered by standards
   of performance as those exceeding 560 CID/cyl.   This alternative would
   exclude  engines presently  manufactured  by  Waukesha  as  well  as  those
   produced  by Caterpillar, Detroit  Diesel, and Cummins.  This  definition,
   however,  shifts  the area of overlap  1n  horsepower between regulated and
   unregulated engines to other large-bore dlesel manufacturers.  This
   situation 1s depicted 1n Figure 9-5, which Illustrates the relationship
  between displacement per cylinder and rated (continuous)  horsepower.   All
  Waukesha  engines are excluded  above the 560 CID/cyl  limit.   However,
  Superior's dlesel engines ranging  In size  from  596-  to  825-CIO/cyl  would
  be  subject to standards.  These engines  compete  1n very few  cases with
  «au*esha dlesel  engines.  Raising  the  Hm1t to 700-CID/cyl would  exclude
  Superior engines  1n the 500- to  100-hp range, but It  would also exclude
  EMD and Alco models, which compete with Colt (700-CID/cyl, hence  regula-
  ted) 1n the 1000- to 3000-hp range.  Establishing a 560-CID/cyl  defini-
  tion, therefore, appears to be  a viable method of excluding engines which
 compete with medium-bore designs without Introducing  a significant over-
 lap  problem at a different power level.
      After  considering  the sizes and  displacements offered  by  each
 dlesel manufacturer and the applications  served by dlesel engines, a 560-
 CID/cyl definition was selected as  a reasonable approach for separating
 large-bore engines that compete with medium-bore engines from large-bore
engines that compete solely with each other.   This cylinder displacement
size was chosen  because engines  below this size are generally used for
                                 9-21

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  different  applications  than  those above  1t.  Therefore,  1t  1s  recommended
  that  dlesel  engines greater  than 560 CID/cyl be affected by  standards of
  performance.
  Affected Dual-Fuel Engines
       The concept of dual-fuel operation was developed to take  advantage
  of both compression Ignition performance and Inexpensive natural gas,
  These engines have been used almost exclusively for prime electric power
  generation,  Figure 9-6^19"22) Illustrates, however, that shortages of
  natural gas and the 1973 oil  embargo have combined to significantly
  reduce the sales of these engines In recent years,  The few large-bore
 units that were sold  (11 1n 1976) were  all  greater than 350 CID/cyl.   In
 fact,  with the exception of Superior D1v1s1on/Cooper and Stewart-Steven-
 son (modified Detroit  Diesel  engine) products,  all were greater than  500
 horsepower and 1000 CID/cyl  as  shown 1n  Figures  9-7 and  9-8.   Moreover,
 nearly all  of the  dual-fuel  engines  sold  since  1972 have been larger  than
 1000  hp,   Only Stewart-Stevenson  manufactures dual-fuel  engines less  than
 560 CID/cyl,   Sales of  these  units are less  than 100  units  per  year and
 about  70 percent of these are exported,^3)
     Although  a greater-than-350-CID/cyl  limit would  subject  nearly all
 new dual-fuel  sources to standards of performance  (only  engines manu-
 factured by Stewart-Stevenson would  be excluded),  1t  1s  recommended that
 the definition chosen to define affected dlesel  engines  (560 CID/cyl)
 also be applied to  dual-fuel engines.  The reason  1s that supplies of
 natural gas are likely to become even more scarce,  possibly causing
 recently installed or future dual-fuel units to  convert to diesel fuel
operation.   Any additional  diesel  engines that would be created by con-
                                  9-23

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  version  from dual-fuel  operation  should  be  subject  to  the  same  regula-
  tions  applicable  to  other  large diesel engines.
  Affected Gas Engines
      The primary  application of large  (greater than 350 CID/cyl) gas
  engines during the past  five years has been for oil and gas production.
  The primary  uses  are to  power gas compressors for recovery, gathering,
  and distribution.  Figure 9-9(24~29\ based on manufacturer's data from
  response to  the June 16, 1976 Section 114 requests for information,
  illustrates  that  75 to 80 percent of all  gas engine horsepower sold
 during the past five years was used for these applications.
      During this time sales to pipeline transmission applications de-
 clined.  Pipeline applications combined with standby power, electric
 generation, and other services (industrial  and sewage  pumping).   These
 other  applications accounted for  the  remaining 20  to 25 percent  of
 horsepower  sales.   The  growth  of oil  and  gas production applications
 during  this period corresponds  to  the increasing efforts to find  new,   or
 recover marginal,  gas reserves  and distribute  them to the existing
 pipeline  transmission network.
     Figure 9-10 illustrates the number of gas engines  sold for five  size
 groups  during  the  past five years.  The large number of smaller-than-500-
 hp engines  that were sold during this period are one or two cylinder
 engines used  on oil well  beam pumps and for natural gas well recovery and
 gathering.  Most of the other larger gas engines that were  sold during
 this period ranged from 500 to 2000 hp.   In 1976,  approximately 400
engines in this size range were sold,  primarily for oil  and  gas production
 (see Figure  9-9).   Most  of these gas  engines  were  manufactured  by Cater-
                                  9-27

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pillar, Cooper,  Waukesha,  and White Superior.
     With the exception of standby service,  all  the applications of
Figure 9-9 are high usage (approximately 6000 hr/yr), and therefore,
contribute significant NOX emissions.  It 1s estimated that the 400,000
horsepower of large-bore gas-engine capacity sold for oil and gas pro-
duction  applications 1n 1976 emitted 34,900 megagrams of NOX emissions,
or nearly three times more NO, than was emitted by the 200,000 horsepower
of large-bore dlesel engine  capacity (greater than 350 CID/cyl) sold for
 the  same application In that year (see  Section  3.1).  Thus,  large-bore
 gas  engines  are primary contributors of NOX  emissions from  new  stationary
 1C  engines,  and standards of performance  should be directed particularly
 at  these sources.
      If affected  engines  were defined  as  those  greater  than 350 CID/cyl,
 then all manufacturers of gas engines  greater than 500  hp,  except Cater-
 pillar, would be  affected by proposed  standards of performance.  However,
 large Caterpillar gas engines range from 225 to 930 horsepower, and
 therefore, compete with  the other large-bore manufacturers  (particularly
 Waukesha).  Figures 9-11 and 9-12 show more clearly the overlap  1n horse-
 power provided by manufacturers  of engines of  various cylinder displace-
 ments.   Therefore, a  greater-than-350-CID/cyl  limit would  give one manu-
 facturer an  unfair competitive  advantage over  other large-bore engine
 manufacturers.  Thus,  although  a greater-than-350-CID/cyl  limit  would
  subject most significant gas engine sources  of NO,  emissions  to  potential
  standards of performance, this  definition  should be revised based on the
                                        >
  following considerations:
                                    9-30

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      •    The greater-than-350-CID/cyl  definition  excludes  the  only other
           manufacturer (Caterpillar)  of gas  engines  greater than  500 hp.
           Caterpillar gas  engines  compete  directly with  the large gas
           engines  manufactured  by  Cooper,  Waukesha,  and  White Superior,
           which  would be regulated.
      t    No  emissions have  been measured  or control  techniques demon-
           strated  for 1- and  2-cylinder engines which would  be  included
           in  potential  standards of performance by the existing greater
           than 350 CID/cyl limit.
      The  first observation suggests that the  definition  should be  lowered,
or another definition  adopted,  to  include  the large Caterpillar engines
that  compete  in  identical applications  with Cooper, Waukesha, and White
Superior  units.  Although Caterpillar has  not reported controlled emissions
data  for  their gas engines, control techniques have been demonstrated on
other  similar gas engines and should be effective when applied to Cater-
pillar engines,  since  they are  all  similar in design (i.e., carbureted
and gas injected engines that are either turbocharged and aftercooled or
naturally aspirated).
     Table 9-5 compares large Caterpillar gas engines with Waukesha
models that are greater than 350 CID/cyl.  As this  comparison illus-
trates, Caterpillar engines with smaller displacements per cylinder and
greater numbers of cylinders serve  about the same power range as do the
larger Waukesha engines.  On the basis of this table, either of  the
following  two  steps would subject Caterpillar gas  engines to potential
standards  of performance:
                                 9-33

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       •    Select a definition of greater than 240 CID/cyl
       •    Define affected gas engines as those greater than 350 CID/cvl
            or greater than or equal  to 8 cylinders and greater than 240
            CID/cyl
       Both  measures would  essentially include  only Caterpillar engines
  in  the same  power  range as  Waukesha.   The  second  definition has  a
  slight advantage over  the first  since 1t includes  only  Caterpillar
  engines  that  have  Waukesha  counterparts  of about  the  same power  (note
  that  the greater-than-240-CID/cyl definition  alone would include the
  Caterpillar G353,  which has no large Waukesha counterpart).  Therefore,
  the greater-than-350-CID/cvl or greater-than-or-equal-to-8 c.yl inders
  and greater-than-240-CID/cvl definition of affected gas engines is
  recommended.
      With regard to one and two cylinder engines,  it is recommended
 that they be excluded from potential standards of  performance.  This
 suggestion  can be supported considering:
      •   At  present these engines  account  for less than 10  percent of
          all  gas engine horsepower  and,  therefore,  are  less signifi-
          cant NOX  emitters  than  the larger gas  engines  used for  oil
          and  gas production
     •   These  sources are  numerous  and  widely  dispersed in  remote lo-
          cations
     •    These  engines are  low rated* and therefore, probably have
          lower  NOX emissions than the larger  higher-rated gas engines
     In addition to these factors, consideration should be given to the
*0perate at a small  fraction of their potential power output.

                                 9-35

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undeveloped control technology for these engines.  A spokesman for one
manufacturer noted that they are only currently preparing to measure
NO  emissions from their one- and two-cylinder engines.  Therefore, it
  "       .
is recommended that all one- and two-cylinder gas engines be exempted
from potential standards of performance.
     In summary, then, it is recommended that the following criteria
define gas engines that are to be affected by standards of performance:
     •    Affected facilities are defined as engines  that are  either
          greater  than 350-CID/cyl or greater than  8-cylinder  and
          greater  than 240-CID/cyl
     t    All  one  or  two cylinder gas engines are exempt  from  standards
          of performance
 9.4  SELECTION OF  BEST SYSTEM OF EMISSION  REDUCTION
     As  discussed  in  Chapter 4,  four emission control techniques,  or
 combinations of these techniques,  have  been  identified as demonstrated
 NO  emission reduction systems  for stationary  large-bore internal
   /\
 combustion engines.   These techniques are:   (1) retarded ignition or
 fuel injection, (2)  air-to-fuel  ratio changes,  (3)  manifold air cooling,
 and  (4)  derating power output (at constant speed).    In general, all
 four techniques are applied by changing an engine operating adjustment.
 Manifold air cooling, however,  may require a larger  heat exchanger, and
 air-to-fuel changes may require turbocharger resizing.
      These  control techniques, described in Chapter  6, reduce NOX
 emissions primarily  by lowering peak flame temperatures.  Some  of  the
 techniques  may  result in increased  fuel consumption  and/or engine  main-
 tenance.
                                   9-36

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       Fuel Injection retard 1s the most effective NOX control technique
  for dlesel-fueled engines, achieving maximum NOX reductions of about 65
  percent.   Similarly, air-to-fuel  ratio change 1s the most effective NO
                                                                        rt
  control  technique for natural  gas engines,  achieving maximum NOX
  reductions of about 80 percent.   Both retard and air-to-fuel  ratio  changes
  are effective in  reducing  NOX  emissions  from dual-fuel  engines,  achieving
  maximum NOX  reductions of  about 70  percent.
       Other NOX  emission  control techniques  exist but  are  not  considered
  feasible  alternatives.   These  techniques, also described  1n Chapter 6,
  Include exhaust gas  ^circulation (EGR), combustion chamber modification
  (CCM), water  Induction,  and catalytic reduction.
      Exhaust gas redrculatlon tests have shown effective NO  reduc-
                                                             n
  tlonsj however, the necessity for cooling the redrculated gas may lead
  to contamination of flow passages  1n the cooling  heat exhanger as well
 as 1n the  engine turbocharger and  aftercooler. At present there Is
 Insufficient data  on which  to base conclusions and more  development  1s
 required.   Therefore, 1t 1s not considered a demonstrated  emission
 control technique.
      Data  from smaller-bore dlesel engines Indicate  that combustion
 chamber configuration  has a significant effect on  NOV  emissions.
                                                     A
 However, none  of the  domestic large-bore engine manufacturers  has
 thoroughly  studied the  effects of modified combustion  chamber  geometries
 on NOX emissions.  Manufacturers have estimated that an extensive
development program of  three to five years would be required to establish
the emission benefits of such a major engine  redesign.  The majority  of
the existing engines  are primarily  long-established designs that have
                                 9-37

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been refined over the years to Improve fuel  economy and maintenance.
Since there 1s Insufficient data to draw conclusions,  combustion cham-
ber modification 1s not considered a demonstrated emission control
technique.
     The effect of water Induction 1n large stationary Internal combus-
tion engines  1s similar to the effect 1n gas turbines.  Significant NOX
reductions  are achieved due to the quenching effect of the presence of
water.  However, as  discussed 1n Section 4.4.7, tests with water Induc-
tion 1n large stationary Internal  combustion engines  have shown unaccept-
able deposit  bund-up  on the  exhaust/Intake valves  from the use of
untreated  water, and severe lubricating  oil contamination.  Therefore,
water  Induction  1s also  not considered  a demonstrated control  technique.
      Catalytic  reduction of NOX  1n large stationary Internal  combustion
 engines  1s difficult to  achieve  and the capital  cost  could  be high.
 Most large stationary Internal  combustion  engines operate at  air-to-
 fuel  (I.e., mass flowrate  [g/hr] of air Into  an  engine divided by the
 mass flowrate of fuel [g/hr]) ratios that  are typically much  greater
 than sto1ch1ometr1c and consequently the engine exhaust 1s character-
 ized by high oxygen concentrations.  Existing automotive catalytic
 converters,  however, operate near sto1ch1ometr1c conditions  (I.e., low
 exhaust oxygen concentrations).   These  automobile  catalysts  are not
 effective  1n reducing NO  1n the  presence of high  oxygen concentrations.
                         A
 Consequently, entirely different  catalyst systems  would  be needed to
 reduce NO  emissions  from large  stationary Internal  combustion engines.
           /\
 Although  such  catalyst  systems  are  currently under development and have
 been  demonstrated for one very  limited  application (i.e.,  fuel-rich
                                   9-:

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   naturally aspirated gas engines),  they have not been demonstrated for
   the broad range of 1C engines  manufactured,  such as  turbocharged en-
   gines,  fuel-lean gas  engines,  or diesel  engines.   For these  engines  the
   reduction of NOX by ammonia  injection  over  a  precious  metal  (e.g.,
   Platinum)  catalyst  appears promising with NO, reductions of  approximately
   90  percent having been  reported; however, the cost of  such a system  is
   high.
       For a typical 1000 horsepower engine approximately 2 cubic feet of
  honeycomb catalyst (platinum based) would be required to ensure proper
  operation of the system.  The cost  of the catalyst was estimated at
  $1500/cubic foot (in 1973).   Assuming that the engine costs $150/hp and
  that the cost of the catalyst accounts  for about  one-half the cost of
  the  whole  system (container,  substrate, and  catalyst),  the capital
  investment  for this  control system  represents  approximately four  percent
  of the engine purchase price.
      The amount of ammonia required for an ammonia/catalyst NOX reduc-
 tion system will  depend on the NOX emission rate  (g/hp-hr).   Ba'sed on
 uncontrolled NOX  emission rates  of 9 to 22 g/hp-hr, and the  cost of
 $150/ton  for the  ammonia, the  cost impact  of  injecting ammonia is
 approximately 5 to 15 percent  of the total  annual  operating costs
 ($/hp-nr)  for natural gas engines.   When this operating  cost is  com-
 bined with  the capital cost of the catalytic  system discussed  above,
 the total cost increase is about 25  percent.  Therefore, in continuous
service applications this system is expensive compared to control
techniques such  as retard or air-to-fuel ratio changes.
                                   9-39

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     It 1s also Important to note that the consumption of ammonia can
be expressed as a quantity of fuel since natural gas 1s generally used
to produce ammonia.  Assuming a conservative NOX emission rate of 20
g/hp-hr, and engine heat rate of 7500 Btu/hp-hr, a heating value of
21,800 Btu/lb  for natural gas, and a requirement for approximately 900
Ibs of gas per ton of ammonia produced, then the ammonia necessary for
the catalytic  reduction  has  the  same effect on  the  supply of  natural
gas as  a  2-percent  Increase  1n fuel consumption.  Additional  fuel  1s
required  to  operate  the  plant which produces the  ammonia.
      Catalytic reduction,  therefore,  is currently not a demonstrated
NO  emission control  technique which  could be  used  by all  1C  engines.
   A
Consequently,  although catalytic reduction of  NOX emissions could be
 used in a few isolated cases to  comply with standards of performance,
 1t could not  be used as the basis for developing standards of perfor-
 mance which are applicable to all 1C engines.
      In  summary, four emission  control techniques have been  identified
 as demonstrated NOX emission reduction systems for stationary large-
 bore internal combustion engines.  These  techniques  are:   (1) retarded
  ignition or fuel  injection,  (2)  air-to-fuel ratio  changes,  (3)  manifold
  air  cooling,  and  (4)  derating power  output  (at constant speed).   Fuel
  injection retard  is  the most effective NOX  control  technique for diesel-
  fuel  engines  and  air-to-fuel  ratio  change is  the most effective NOX
  control  technique for gas engines.   Either technique is effective for
  dual-fuel engines.
       The data and information presented  in Chapters 4 and 6 clearly
   indicate that application of the control techniques mentioned above
                                   9-40

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  will  reduce  NOX  emissions  from  Internal  combustion  engines.   It Is  not
  immediately  clear,  however,  from  this data  and  Information whether  the
  application  of these emission control techniques  to all  1C engines
  would reduce NOX emissions to a specific level due to Inherent  differ-
  ences 1n the uncontrolled emission characteristics of various engines.
  In general, engines with high uncontrolled NOX emission levels  have
  relatively high controlled  NOX emission  levels and engines with low
  uncontrolled  NOX  emission levels have relatively low controlled NO,
  emission levels.   To eliminate these  Inherent differences in  NO,
  emission characteristics  among various engines,  the  data  were analyzed
  In  terms of the degree  of reduction in NO, emissions as a function of
  the degree  of application of  each  emission control technique.   Figures
  4-27 and 4-31, reproduced here as  Figures 9-13 and 9-14,  Illustrate  the
 overall  effectiveness of  ignition  retard and air-to-fuel  ratio changes
 for reducing NO, emissions.   For example, in Figure 9-13,  the applica-
 tion of approximately eight  of Ignition retard results  in  about 40
 percent reduction  of NOX emissions. Thus, the data presented  in Chapters
 4 and  6 demonstrate that the same degree  of application of each of
 these  four NOX emission  control techniques - I.e.,  (1)  retarded ignition
 or  fuel  Injection,  (2) air-to-fuel  ratio  changes,  (3) manifold air
 cooling,  and (4) derating  power output  (at constant speed)  -  will
 result  in essentially the  same degree of  reduction of NOX  emissions
 from all  large stationary  Internal  combustion engines.  Consequently,
the ability to  achieve certain percentay, reductions in N0¥ emission
                                                          A
levels  Is clearly demonstrated.
     As can be  seen from  Figures 9-13 and  9-14, those  Included  In
                                 9-41

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Chapters 4 and 6, a wide range of regulatory options (I.e., basis for
standards) 1s available.  The greatest reductions 1n NOX emissions,
achieved with some degree of consistency by the use of these four
demonstrated NO  control techniques, was approximately 60 percent.
               n
Therefore, 60 percent reduction was Initially selected 1n Chapter 6 as
the most stringent regulatory option that could serve as the basis for
the standards.  Alternative regulatory options of 20 and 40 percent
reduction were selected as representative of less stringent basis for
standards.
      Subsequent  review  and analysis, however,  Indicate that technical/
hardware  considerations limit  the  percentage NOX  reduction  that  can  be
achieved  1n  practice.   Generally  Ignition  retard  1n  excess  of  eight
degrees 1n  dlesel-fueled  engines  frequently leads to unacceptably high
exhaust temperatures,  resulting  1n exhaust valve  and/or  turbocharger
 turbine damage.   Similarly,  changes 1n  the air-to-fuel  ratio  1n  excess
 of five percent 1n gas engines frequently  leads  to excessive  misfiring
 or detonation which could lead to a serious explosion 1n the  exhaust
 manifold.  As shown 1n Figures 9-13 and 9-14,  eight degrees of Ignition
 retard 1n dlesel-fueled engines and five percent change 1n air-to-fuel
 ratios 1n gas-fueled engines yield about a 40 percent reduction 1n NOX
 emissions.  Consequently, 1n light of these limitations to the applica-
 tion of these emission control techniques, it is apparent that a 40-
 percent reduction 1n NOX emissions is the most stringent regulatory
 option which could be  selected as  the basis for  standards of  performance,
 An alternative  of 20 percent NOX  emission  reductions was also considered
 a viable  regulatory option which  could  serve  as  the basis  for standards.
                                   9-44

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  Environmental  Impacts
       Standards of performance based on alternative I (20-percent reduc-
  tion) would reduce national NOX emissions of about 14.6 million mega-
  grams per year for all stationary sources by 72,500 megagrams annually
  In the fifth year after the standard went Into effect.   In contrast,
  standards of performance based on alternative II (40-percent reduction)
  would reduce national  NOX emissions  by about 145,000  megagrams annually
  In the  fifth year after the standard went Into  effect.   Thus,  standards
  of performance  based on alternative  II  would have  a much greater  Impact
  on national  NOX emissions  than standards  based  on  alternative  I.
       As discussed  In Chapter 7, ambient air  quality dispersion modeling,
  based on  "worst case" conditions, indicates  uncontrolled ambient air
  NOX levels near large stationary internal combustion engines can vary
  from approximately 60 percent of the National Ambient Air Quality
 Standard of 100 yg/m3 to over twice the standard depending on the size
 of the engine.  One calculation for a large gas engine yielded an
 uncontrolled  ambient NOX level  of about 220 wg/m3.
      These maximum concentrations,  however,  are  located  at distances  ex-
 tremely  close to the  source (0.3  km)  because  of  the aerodynamic effects
 on  plume rise as well as the relatively  low  height  of  the exhaust stack
 discharge.  For  example,  it is estimated that at  1.0 km  from  the source,
 those  concentrations would  be only 15 percent of  the above cited levels,
well below the National Ambient Air Quality Standard.
     In any event,  standards of performance based on alternative I
would reduce the highest calculated ambient air concentration of 220
                                 9-45

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wg/m3 to about 180 ug/ni3,  while standards based on alternative II  would
reduce this ambient NOX concentration level  to about 100 ug/m3.   Thus,
where ambient air NOX concentrations near large stationary internal
combustion engines would be significant, standards of performance based
on alternative II would be more effective in reducing ambient air NOX
levels  than standards of performance based on  alternative I.
      Standards of performance  based on  either  alternative would, with
the  exception of naturally aspirated gas engines,  not  significantly
effect carbon monoxide  (CO)  or hydrocarbon  (HC)  emissions from  most
engines.   A typical  diesel engine with  a sales-weighted average uncon-
 trolled CO emission level  of approximately  2.9 g/hp-hr would experience
 an increase in CO emissions  of about 0.75 g/hp-hr (26 percent)  to
 comply with standards of performance based  on alternative I, and an
 increase of  about 1.5 g/hp-hr (52 percent)  to comply with standards of
 performance  based on alternative  II.   Total hydrocarbon emissions would
 increase  a sales-weighted average uncontrolled  emission level  of  0.3
 g/hp-hr  by about 0.06  g/hp-hr (20 percent) to comply with  standards
 based on alternative  I,  and would increase by about 0.1 g/hp-hr  (33
 percent) to  comply with  standards of  performance based on  alternative
  II.
       Similarly, a typical dual-fuel engine with a sales-weighted average
  uncontrolled CO emission level of approximately 2.7 g/hp-hr would
  experience an  increase in CO emissions of about 1.2 g/hp-hr (44 percent)
  and about 2.7  g/hp-hr (100 percent) to comply with standards of perfor-
  mance  based  on alternatives  I  and  II, respectively.  Total hydrocarbon
                                    9-46

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 emissions,  however,  would  decrease  by  about  0.3  g/hp-hr  (11  percent)
 from  a  sales-weighted  average  uncontrolled level  of  a  approxlmatley 2.8
 g/hp-hr to  comply with standards  of performance  based  on  alternative  I.
 To  comply with  standards of  performance  based on  alternative  II  total
 hydrocarbon emissions  would  decrease 0.6 g/hp-hr  (21 percent).
      A  typical  turbocharged  or blower  scavenged gas  engine with  a
 sales-weighted  average uncontrolled  CO emission level  of  approximately
 7.7 g/hp-hr would experience an increase 1n  CO emissions  of about  1.9
 g/hp-hr (25 percent) to comply with  standards of  performance  based on
 alternative I and about 3.8  g/hp-hr  (49 percent)  to  comply with  stan-
 dards of performance based on  alternative II.  Total hydrocarbon emis-
 sions would  increase a sales-weighted average uncontrolled level of
 approximately 1.8 g/hp-hr  by about 0.2 g/hp-hr (11 percent) to comply
 with  standards  of performance  based  on alternative I.  To comply with
 standards of performance based on alternative II  total hydrocarbon
 emissions would increase by  about 0.4 g/hp-hr (22) percent.
     A  typical  naturally aspirated gas engine with a sales-weighted
 average uncontrolled CO emission level  of approximately 7.7 g/hp-hr
would experience an increase in CO emissions of about 3.9 g/hp-hr  (51
 percent) to comply with standards of performance based on alternative I
and about 17 g/hp-hr (220 percent) to comply with standards of perfor-
mance based on alternative II.   Total hydrocarbon emissions would
increase a sales-weighted average uncontrolled level  of approximately
1.8 g/hp-hr by about 0.04 g/hp-hr (2 percent) to comply with standards
of performance based on alternative I.   To  comply with standards of
performance based  on alternative II  total  hydrocarbon emissions would
                                 9-47

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Increase by about 0.08 g/hp-hr (4 percent).
     The increase in ambient air CO levels due to compliance with NOX
standards of performance based on either alternative would be small.
For most engines,the application of standards of performance based on
Alternative I would increase the maximum 8-hr ambient air CO concentra-
tion from about 0.23 mg/m3 to 0.29 mg/m3 for the typical diesel  engine
mentioned above.  The application of standards of performance based on
alternative II would increase the maximum 8-hour ambient air CO concen-
tration to 0.35 mg/m3.  These values are insignificant compared to the
National Ambient Air Quality Standard of 10 mg/m3 for CO.
     The application of standards of performance based on alternative I
would increase the maximum 8-hr ambient air CO concentration from an
                                       3             3
uncontrolled concentration of 0.65 mg/m  to 0.94 mg/m  for the typical
dual-fuel engine mentioned above.  The application of standards of
performance based on alternative II would increase the maximum 8-hr
                                        3
ambient air CO concentration to 1.3 mg/m .
     For a typical turbocharged or blower scavenged gas  engine, the
increase in the maximum 8-hr ambient air CO concentration would be even
less.  The application of standards of performance based on  alternative
I would increase the maximum 8-hr  ambient air CO concentration from  an
                                       o             o
uncontrolled concentration of 0.15 mg/m  to 0.19 mg/m .  The applica-
tion of standards of  performance based on alternative II would increase
the maximum 8-hr ambient  air CO  concentration to 0.22 mg/m  .  These
values  are also  insignificant compared to the National  Ambient Air
Quality Standard.
                                  9-48

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        For  a  typical  naturally  aspirated  gas  engine,  the  application  of
   standards of  performance  based on alternative  I would Increase  the
  maximum 8-hr  ambient air  CO concentration from an uncontrolled  concen-
  tration 0.77 mg/m3  to 1.16 mg/m3.  The application of standards of
  performance based on alternative II would Increase the maximum 8-hr
  ambient air CO concentration to approximately 2.0 mg/m3.
       Based on Industry growth projections,  an Increase In national CO
  emissions  of about 63,000 megagrams  annually would be realized in  the
  fifth year after the standards go Into effect as  a result of standards
  of performance based on  alternative  I.   As  a result  of standards of
  performance  based  on alternative  II  an  Increase of about 216,000 mega-
  grams  annually would be  realized  1n  the  fifth year after standards go
  Into effect.
      The large Increase  1n CO emissions  Is due primarily  to carbureted
 or naturally aspirated gas engines.  These engines operate closer to
 Sto1ch1ometr1c conditions under which a small change 1n the air-to-fuel
 ratio results In a large Increase in  CO emissions.   As shown 1n Figure
 9-15,  any significant NOX reduction 1s accompanied  by a significant
 Increase in CO.
     As discussed earlier,  though  the total  national  CO emissions would
 increase significantly, ambient  air CO  concentrations  in  the  immediate
 vicinity of these carbureted or  naturally aspirated gas engines would
 not be  adversely  affected.  As a result of the standards  of performance
 based on alternative  II,  the maximum 1 hour ground  level concentration
 from a typical engine would increase to about 2 mg/m3 compared to the
National Ambient Air Quality Standard  of 10 mg/m3.   Ambient air NO
                                 9-49

-------An error occurred while trying to OCR this image.

-------
   concentrations  from  the  same  engine,  however, would decrease concurrently
   about 40 percent, to a level  less than half of the National Ambient A1r
   Quality Standard of  100  ng/m3.
       Thus, there exists  a trade-off between NOX emissions reduction and
   CO emissions Increase,  particularly for carbureted or naturally aspirated
  gas engines.   EPA recognizes this trade-off and 1s concerned about It's
  attractiveness.   It should be noted  though that CO emissions are a local
  problem since they rapidly oxidize to C02.   Additionally,  most  naturally
  aspirated  gas engines are operated in remote locations where CO is not a
  problem.   NOX emissions,  however,  are linked  to the formation of photo-
  chemical oxidants  and are subject  to  long  range transport.   N0¥  emissions
                                                               rt
  reductions are also much  harder to achieve  than CO or HC emissions
  reductions which may be achieved more  easily from other sources.
      One alternative is to propose a CO emissions limit based on the
 use of oxidizing catalysts.  These catalysts can provide CO and HC
 emissions reductions on  the order of 90 percent.   Initial  capital costs
 are high, however,  averaging about $7500 for a typical  1000 horsepower
 naturally aspirated gas  engine or about 15  percent  of  the  purchase
 price  of the engine.
     EPA  feels these costs for  control  of CO emissions are  unreasonable.
 The  trade-off  between  NOX  and CO emissions,  however, seems  reasonable.
 Therefore, CO  was not  selected  for  control by standards of  performance.
     Hydrocarbon emissions  are  also currently considered a  pollutant of
concern due to the impact  on ambient air oxidant concentrations.
However, although relationships are being developed  to predict the HC
emissions impact on  oxidant concentrations,  these concentrations  depend
                                  9-51

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on the ambient air NO/HC ratio,   Thus, 1t 1s difficult to estimate the
                     n
Impact of Increased HC emissions on ambient air oxldant concentrations.
Furthermore, based on data 1n Appendix C.4, 1t 1s estimated that more
than 90 percent of the total hydrocarbon emissions from gas engines and
75 percent of the total hydrocarbons from dual-fuel engines are methane,
which  1s nonreactlve and does not lead to oxldant formation.  Finally,
the  Increase  1n national total HC emissions based on either alternative,
for  most engines,  1s very  small.
      Standards of  performance based on alternative  I would  Increase
national total HC  emissions  of  10.2 million  megagrams  by  about  2,300
megagrams  annually 1n  the  fifth  year  after the standards  went Into
effect compared  to an  Increase  of about  4,600 megagrams annually associ-
 ated with  alternative II.   Standards  of  performance based on  alternative
 I would Increase national  reactive HC emissions by approximately 108
 megagrams  annually in the fifth year after the standards went into
 effect, compared to an increase of approximately 216 megagrams annually
 associated with alternative II.
       As described in Chapter 3, stationary internal combustion engines
 are sources  of NO , HC and  CO emissions, with both NOX and HC contri-
                  /\
 buting to oxldant formation.  With regard to  regulation  of emission
  from 1C engines,  NOX  emissions  are of more  concern than  emissions of
  hydrocarbons for  two  reasons.   First, NOX  is  emitted  in  greater quantities
  from stationary  internal  combustion  engines  than  hydrocarbons.   Second,
  a high priority  has  been  assigned  to development  of  standards  of per-
  formance  limiting N0¥ emissions from stationary sources  are  projected
                      X
  to increase by more than  40 percent in  the 1975-to-1990 period.  Apply-
                                    9-52

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A
  Ing best technology to all  new sources would reduce this increase but
  would not prevent it from occurring.   This unavoidable increase in NO
  emissions is  attributable largely to  the fact that current NO  emission
                                                               A
  control  techniques  are based  on  combustion redesign.   In addition, few
  NOX emission  control  techniques  can achieve  large  (I.e., in  the range
  of  90 percent)  reductions  in  NOX  emissions.   In  contrast,  HC  emissions
  are much  easier to  reduce.  Large reductions  from  numerous sources are
  achievable with  the  installation  of existing  add-on control equipment.
  Consequently, EPA has  assigned a  high  priority to  the development  of
  standards of performance for major NOX emission  sources wherever signi-
  ficant reductions in MOX can be achieved.
      The slight increase in HC emissions from 1C engines associated
 with control  of NOX from 1C engines can be offset from other sources
 easier than NOX emissions can  be  reduced from other sources.   There-
 fore, the adverse environmental  impact of increased HC emissions due to
 the  reduction  in NOX emissions is considered  small.
      There would be  essentially no water pollution  impact of  standards
 of performance  based  on either alternative  I  or alternative  II.   Only
 one  control technique,  increased  manifold air  cooling,  could  result in
 an additional discharge of water.   However, most  newly  installed  engines
 use  a  closed cooling  system with  no water discharge.
      Standards of performance based on  either  alternative would also
 have no solid waste impact.
     There would also be no adverse noise impact  resulting from stan-
dards of performance based on either alternative.   Fan noise levels
from  large-bore stationary engine  installations could increase slightly
                                 9-53

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as a result of Increased cooling requirements; however,  1n typical
Installations such as municipal generator plants, pipeline compressor
stations or industrial process plants, such Increases are insignificant
in comparison to existing noise levels.
     Thus, as reflected in the summary Table 9-6, the environmental
Impacts of standards  of performance based on either alternative are
small and  reasonable.
Energy  Impacts
     The  potential  energy  impact  of  standards  of performance  based on
either  alternative  is small.   As  discussed  in Section 6.2,  standards of
 performance based on alternative  I  could increase the  fuel  consumption
 of a typical blower scavenged or turbocharged gas engine by approxi-
 mately one percent, whereas standards of performance based on alterna-
 tive II could increase the fuel consumption by approximately two  percent.
 A typical 2000 horsepower blower scavenged or turbocharged gas engine
 has an uncontrolled  fuel consumption of approximately 343,000 scf
 natural gas  per day  (the energy  equivalent of 2842 gallons oil per
 day).  Increases translate  into  actual  increased fuel consumption of
  approximately  3500 scf and  7000  scf  natural  gas per day (the energy
  equivalent of  25 and 50 gallons  oil  per day).
       Standards of  performance based  on alternative I would increase the
  fuel  consumption of a typical naturally aspirated  gas  engine by approxi-
  mately six percent.  Standards of performance based on alternative II,
  however, would increase the fuel consumption by approximately eight
  percent.
       A typical 2000  horsepower  naturally aspirated gas  engine has  an
                                    9-54

-------An error occurred while trying to OCR this image.

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uncontrolled fuel consumption of approximately 343,000 scf natural gas
per day  (the energy equivalent of 2842 gallons oil per day).
     These percentage increases represent actual fuel consumption
Increases of about 20,600 and 27,400 scf natural gas per day (the
energy equivalent of 142 and 189 gallons oil per day).
     Standards of performance based on alternative I could Increase the
fuel consumption of a typical dual-fuel engine by approximately one
percent, whereas standards of performance based on alternative II
could Increase the fuel consumption by approximately three percent.  A
typical dual-fuel engine rated at 2000 horsepower has an uncontrolled
fuel consumption of approximately 297,000 scf natural gas per day  (the
energy equivalent of 2150 gallons oil per day).  These percentage
Increases represent an actual fuel  consumption increase of about 6100
and 12,200 scf natural gas per day (the energy equivalent of 43 and 86
gallons oil  per day).
     Standards of performance based on alternative I could Increase the
fuel consumption of a typical dlesel  engine by approximately three
percent, whereas standards of performance based on alternative II could
Increase the fuel consumption by approximately seven percent.  For a
typical dlesel  engine rated at 2000 horsepower, with an uncontrolled
fuel consumption of approximately 2320 gallons of oil per day,  these
percentage Increases represent actual fuel  consumption Increases of
about 70 and 160 gallons of oil  per day.
     Thus, the potential energy Impact 1n the fifth year after the
standard goes Into effect, based on alternative I, would be equivalent
to approximately 1.03 million barrels of oil per year compared to an

                                   9-56

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uncontrolled fuel consumption of 1C engines affected by the standard of
31 million barrels per year.  The potential energy Impact 1n the fifth
year after the standard goes Into effect, based on alternative II,
would be equivalent to approximately 1.5 million barrels of oil per
year.
     It should be noted that the largest Increase represents only 0.01
percent of the 1977 domestic consumption of crude oil and natural gas.
The largest Increase also represents only 0.03 percent of the projected
total oil  Imported to the United States five years after the standards
go Into effect.
     Thus, as reflected 1n the summary Table 9-7, the energy Impacts of
standards  of performance based on either alternative are small  and rea-
sonable.
              TABLE 9-7.  ENERGY IMPACTS OF ALTERNATIVES
Engine
Fuel
Type
Gasb
Gasc
Dual Fuel
Diesel
Totals of
all new
engines
after
5 years
Uncontrolled9
Fuel Consumption
(gal/day)
2842d
2842
2151
2317
31,000,000
bbls o1l/yr



Increase 1n Fuel Consumption (gal/day)
Alternative I Alternative II
25
142
43
70
1.03 million
bbls oll/yr



50
189
86
162
1.5 million
bbls o1l/yr



  Jyplcal  2000 horsepower engine
  .Blower scavenged or turbocharged
  ^Naturally aspirated
   Expressed as equivalent oil  consumption
                                 9-57

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Economic Impact of Alternatives
     Manufacturers of stationary internal combustion engines would incur
additional costs due to standards of performance.  These costs however
would be small.  As discussed in Section 6.3, these costs are a result
of one or more of the following activities that may be needed to manu-
facture engines which meet standards of  performance:  (1) extended
testing to verify the effectiveness of a particular control approach;
(2)  development and  application of NOX controls  to existing engine
designs;  and  (3)  engineering,  tooling and  pattern  costs  for minor  re-
design  of an  engine  family  to  accomodate application  of  a  control  tech-
nique.   It is estimated that the  total  costs to  the manufacturer for
 each engine  model  family,  including  development, durability tests,  and
 retooling, would  be approximately:   (1)  $125,000 for  retard and air-to-
 fuel change; (2)  $150,000 for manifold  air temperature reduction; and
 (3) $25,000 for derate.  For each manufacturer,  therefore, total costs
 would vary depending on (1) the number  of engine model families pro-
 duced, (2) their degree of  advancement  in emission testing,  (3) the
 uncontrolled emission  levels of their engines,  (4) the development  and
 durability testing  required to produce  engines  that  can meet proposed
 standards of performance, and  (5) the emission  control  technique  selected,
      As  reported  in Section 8.4, the economic impacts on  manufacturers
 arising  from these  cost penalties associated with standards  of perfor-
 mance  based  on either  alternative would be  small.
       The manufacturer's total  capital  investment requirements  for
  developmental  testing of engine models is estimated  to be about $4.5
  million to comply with standards of performance based on alternative  I
                                   9-58

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and about $5 million to comply with standards of performance based on
alternative II.  These expenditures would be made over a two year period.
Analysis of the financial statements of engine manufacturers or their
parent companies Indicates that the manufacturers' overhead budgets are
sufficient to support the development of these controls without adverse
Impact on their financial position.
     As discussed 1n Section 8.4.1.2, manufacturers would not experience
significant differential cost Impacts among competing engine model
families.  The cost penalties summarized 1n Table 8-16 reflect the
range of total annual1zed cost penalties to the end use applications
for each engine fuel type and manufacture for each alternative.  These
costs for each major end use, the cross-price Inelasticities, and the
Importance of each end use market to the companies' total Internal
combustion sales were analyzed to determine the relative sales advan-
tages between companies.  Consequently, these analyses Indicated that
no significant sales advantages or disadvantages would develop among
competing manufacturers for standards of performance based on either
alternative.  Based on "worst case" assumptions the maximum intra-
Industry sales losses would be about six percent as a result of standards
of performance based on either alternative.  Thus, the intra-1ndustry
Impacts would be moderate and not cause any major dislocations within
the Industry.
     These total annualized cost penalties imposed on 1C engines by
standards of performance would also have very little impact with regard
to increasing sales of gas turbines.  Turbines do not compete with
internal combustion engines based on annualized costs alone, due to
                                  9-59

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their higher operating costs (fuel).  As discussed 1n Subsection 8.4.1.3,
the total annual1zed cost penalty associated with standards of perfor-
mance based on either alternative would bring the cost of owning Internal
combustion engines up to that of turbines 1n only one case -- dlesel
Internal combustion engines used 1n electric generation.   This conclusion,
however, 1s based on limited data.   It 1s quite likely, however, that
this manufacturer's line of dlesel  engines, through minor combustion
modifications, could reduce their NOV emission to levels  comparable to
                                    A
that of other manufacturers.  Further, due to technical limitations,
economic considerations, and customer preference, 1t 1s unlikely that
1C engine users will switch to gas  turbines.  For example, 1t 1s unlike-
ly that turbines would replace dlesel engines 1n plants using banks of
smaller engines, unless the entire  bank were replaced with one turbine.
     Standards of performance based on alternative I would result 1n no
loss of sales to gas turbines whereas standards of performance based on
alternative II would result in the  possible loss of sales for one
dlesel manufacturer.
     Thus, the economic Impacts on  the manufacturers arising from
standards of performance based on either alternative are  considered
small  and reasonable.
     The application of NO  controls will also increase costs to the
                          rt
engine user.  The magnitude of this increase will depend  upon the
amount and type of emission control applied.  As was shown in Section
6.3, various control approaches affect Initial costs, fuel consumption,
and maintenance differently.  Fuel  penalites, though, are the major
                                  9-60

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 factor  affecting  this  Increase  for  high  usage  engines.
     The  following  four  end  uses were  selected to  represent  the  major
 applications of dlesel,  dual-fuel,  and natural  gas  engines:   (1)  dlesel
 engine, electrical  generation;  (2)  dual-fuel engine,  electrical  genera-
 tion, (3) gas engine,  oil  and gas transmission and  (4)  gas engine,  oil
 and gas production.
     The  total annual1zed  cost  of a typical uncontrolled dlesel  fuel,
 electrical generation  engine 1s about 2.5^/hp-hr.   For  a typical  2000
 horsepower engine operating 8000 hours per year, this total  annual1zed
 cost would be about $450,000 per year.   Standards of  performance  based
 on alternative I would Increase this total annual1zed cost by about
 0.04^/hp-hr (1.5 percent).  Similarly, standards of performance  based on
 alternative II would Increase the total  annual 1 zed cost by about
 O.lltf/hp-hr (4.5 percent).  For the engine mentioned  above,  these
 values translate Into dollar amounts of  about  $6,400  and $17,600  respec-
 tively.
     The total annual1zed  cost of a typical uncontrolled dual-fuel,
 electrical^generation engine 1s about 2.8^/hp-hr.  For  a typical  2000
 horsepower engine operating 8000 hours per year this would be about
 $448,000 per year.  As a result of  standards of performance  based on
 alternative I this total  annual 1zed cost would  Increase by about 0.07
-------
fuel, oil and gas transmission engine 1s about 2.2<£/hp-hr.  For a
typical 2000 horsepower engine operating 8000 hours per year, this
total annual1zed cost would be about $354,000 per year.  Standards of
performance based on alternative I would Increase this total annual1zed
cost by about 0.02
-------
  would have to expend additional capital to purchase more expensive
  engines.   This capital cost penalty however, 1s small.  A two percent
  Increase  In engine price would be expected on the average as a result
  of standards of performance based on either alternative.   Typical
  Initial costs for uncontrolled dlesel  and  dual-fuel,  electrical  generation
  engines,  and natural  gas,  oil  and gas  transmission  engines  are about
  $150/hp-hr.   Initial  costs for natural  gas fuel,  oil  and  gas production
  engines are  about  $50/hp.   For typical  2000  horsepower engines,  these
  Initial capital costs  would  be about $300,000 and $100,000,  respectively.
      Standards of  performance  based on  either alternative would  Increase
  the Initial  capital cost of  a  typical dlesel or dual-fuel, electrical
  generation engine or natural gas  fuel, oil and gas transmission engine
  rated at 2000 horsepower by about $6000.
      In contrast,  standards of performance based on either alternative
 would Increase the Initial  capital cost of a typical natural gas, oil
 and gas production engine rated at 2000 horsepower by about $2000.
      The  total additional  capital  cost for all  users would equal  about
 $9.6  million  per year on a  cumulative basis on  either alternative
 compared to total  uncontrolled  costs  of all  new  engines of $450 million
 per year.
     As discussed  1n  Section  8.4,  the economic  Impacts  on  users  arising
 from the cost penalties  associated with  standards of performance  based
 on  either alternative would be  small.   In general, these Impacts
 translate Into price increases  for the end  products or  services provided
 by  the Industrial and commercial users of large stationary Internal
combustion  engines.  The electric utility industry would realize a
                                 9-63

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price increase after five years of 0.02 percent to comply with stan-
dards of performance based on either alternative.   After five years,
delivered natural gas prices would increase 0.02 percent due to the
application standards of performance based on alternative I and 0.04
percent due to the application standards of performance based on al-
ternative II.
     Even after a full  phase-in period of 30 years, during which new
controlled engines would replace all existing uncontrolled engines, the
electric utility industry would realize a price increase of only 0.1
percent to comply with standards of performance based on either alter-
native.   Similarly, delivered natural  gas prices would increase only
0.1 percent due to the application of standards of performance based on
alternative I  and 0.3 percent to comply with standards of performance
based on alternative II.  Thus, the economic impacts of standards of
performance based on either alternative are considered small and rea-
sonable.
Conclusions
     Based on  this assessment of the impacts of each alternative, and
given the fact that alternative II achieves a greater degree of NOY re-
                                                                  A
duction, it is selected as the best technological  system of continuous
emission reduction of NO  from stationary large-bore 1C engines considering
                        A
the cost of achieving such emission reduction,  any nonair quality
health and environmental impact and energy requirements.
     Table 9-8, which follows, summarizes the economic impacts of each
alternative.
                                  9-64

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                                       TABLE 9-8   ECONOMIC IMPACTS OF ALTERNATIVES
Impact
Impact on Manufacture
Capital budget requirements
Uncontrolled
Level of Cost
• *
Alternative I
$4.5 million over two years;
able to generate Internally
from profits.
Alternative II
$5 ml 11 (on over two years j able
to generate Internally from
profits.
    Intra-lndustry competition
   Competition from gas turbines
   Impact on End-Use Aoolleitlorn
   Total annual lied costa

     Diesel  fuel,  electrical
     generation

     Dual-fuel, electrical  gen
     eratlon

     Natural  gas fuel,  oil  and
     gas transmission

     Natural  gas fuel,  oil  and
     gas production

  Totals of  all new engines
  after 5 years

  Capital Cost Penalty8

    Diesel  fuel, electrical
    generation or dual fuel,
    electrical generation or
    natural  gas fuel,  oil and
    gas  transmission

    Natural  gas fuel,  oil and
    gas production

  Totals etc.
  .Impact  on  Product  Prices  and
  Users      ~~
  Electricity  prices
 Gas prices
  2,5
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9.5  SELECTION OF FORMAT FOR THE STANDARDS
     A number of different formats could be used to limit NO  emissions
                                                            ^
from large stationary Internal combustion engines.   Standards could be
developed to limit emissions 1n terms of:  (1) percent reduction, (2)
mass emission per unit of energy (power) output, (3) mass emissions per
unit of energy (fuel) Input, or (4) concentration of emissions 1n the
exhaust gases discharged to the atmosphere.
     Analysis of the effectiveness of the various demonstrated NO
                                                                 A
emission control  techniques clearly shows that what 1s demonstrated 1s
the ability to achieve a percent reduction 1n NO  emissions.  In other
                                                ^
words, application of each emission control technique to the same
degree (I.e., eight degrees of ignition retard to five percent change in
air-to-fuel ratios) will result 1n essentially the same percentage reduc-
tion in NO  emissions.  However, a percent reduction format is highly im-
          rt
practical for two reasons.  First a reference uncontrolled N0¥ emission le-
                                                             o
vel would have to be established for each manufacturer's engine, a diffi-
cult task since some manufacturers produce as many as 25 models which
are sold with several ratings.  Second, a reference uncontrolled NOY
                                                                   ^
emission level would have to be established for any new engines developed
after promulgation of the standard.  This would be quite simple for
engines that employed NO  control techniques such as ignition retard or
                        A
air-to-fuel ratio change to comply with standards.   Emissions could be
measured without the use of these techniques.  For engines designed to
comply with the standards through the use of combustion chamber modifi-
cation, however,  this would not be possible.  Thus, new engines would
receive no credit for the NO  emission reduction achieved by combustion
                            A
                                  9-66

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  chamber redesign.
       A mass-per-un1t-of-energy-output format,  typically referred to as
  brake-specific  emissions  (g/hp-hr),  relates  the  total  mass  of NO
                                                                  A
  emissions  to  the engine's  productivity.  Although  brake-specific mass
  standards  (g/hp-hr)  appear meaningful  because  they relate directly  to
  the quantity  of emissions  discharges  Into  the  atmosphere, there  are
  disadvantages In that enforcement of mass  standards would be  costly and
  complicated in practice.   This can be  Illustrated  by examining the
  relationship  between brake-specific mass emissions  (BSNO ) and the
                                                         /\
  parameters that would have to be measured  1n the field:
                     BSNOX^ NOX (me) (1/w)
 where:
           BSNOX  * grams N0x/horsepower-hour
           NOX    » concentration of NOX in exhaust,  parts per million (ppm)
           me    « exhaust  mass flowrate,  Ib/hr
           w     - power output,  horsepower
     Thus,  exhaust  flow and power  output  would  have to  be determined  1n
 addition to NOX  concentration.   For  example,  to determine exhaust gas
 flowrate, one  of  three methods can be  used:   (1)  directly measure exhaust
 volume  flowrate:  (2) measure  inlet air and fuel  flowrate; and (3)
 measure  all exhaust carbon  constituents (primarily  HC,  CO, C02),  and
 fuel flow,  and conduct a fuel  analysis.
     Since  large internal combustion engines have very  large exhaust
flowrates (in excess of 50,000 cfm),  exhaust flowrates  are difficult to
determine accurately in either the field or laboratory.   Similarly, the
accurate measurement of inlet  airflow is difficult.   Thus,  methods (1)
                                 9-67

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or (2) are unlikely to be used 1n practice for large engines.
     Although method (3) has been used 1n the field to determine brake-
specific mass emissions, the measurement of three additional exhaust
gas constituents and the fuel analysis considerably complicate the test
procedure^31).  Moreover, 1t 1s difficult to accurately measure fuel
flow over a short Interval (typically less than 1/2 hour, which would
be required for a performance test).  Thus, the determination of exhaust
gas flowrates 1n the field 1s difficult and complicated.
     Another disadvantage of the brake-specific mass emissions format  1s
that  power output must  be determined.  Power can be determined from an
engine  dynamometer  1n the laboratory, but dynamometers  cannot be used  1n
the field.  Power output could be determined by:   (1)  Inferring the
power from engine operating  parameters  (fuel flow,  rpm,  manifold pressure,
etc.) or  (2)  Inferring  engine  power from  the output of the  generator or
compressor attached to  the  engine.   In  practice,  however, these approaches
are  time  consuming  and  are  less  accurate  than  dynamometer measurements.
      A  format limiting  NOX  emissions per unit  of energy (fuel)  Input
would be  specified  1n terms of grams NOX per joule fuel Input (equiva-
 lent to Tb  NOV/M Btu).   The advantage of this  format 1s that no power
              A
 measurement would be required, thereby simplifying enforcement.   How-
 ever, as  with a brake-specific mass emission format,  total  exhaust gas
 mass flowrates must be calculated,  and as was discussed earlier,  all
 methods for this determination are difficult under field conditions.
      In addition,  standards of performance based on fuel Input could
 penalize more efficient engines, which typically operate at higher
 temperatures and pressures, leading to higher NOX emissions.  For ex-

                                   9-68

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   ample,  given  two  engines  with  the  same  brake-specific  emissions,  the
   more  efficient  engine, which consumes less  fuel, will  have  a  higher
   fuel-based emissions level because  the  ratio of mass NOX emissions per
   unit  of fuel energy Input has  a smaller denominator.  Thus, this  format
   could offset other Incentives manufacturers have to develop more  effi-
  cient engines.
       Another possible format would be to limit the concentration of NOX
  emissions  1n the exhaust gases  discharged to the atmosphere.  Concentrations
  would  be spedfed  1n  terms of parts of NO,  per  million  (ppm) parts of
  exhaust  (volumetric).   The major  advantage  of  this  format  1s In  the
  simplicity of  Its  enforcement.  As  compared  to  the  formats discussed
  previously, only a minimum of data  and calculations  are  required,  which
  decreases testing costs and minimizes errors In determining  compliance
  with an emission standard.  Measurements are direct; only NOX and  02
  concentration measurements of exhaust gas must be made.   The NOX measure-
 ment reads out directly in ppm of dry exhaust,  and the oxygen measure-
 ment, required  to prevent a user from diluting  the exhaust gas with air
 and lowering  the  NOX  concentration,  reads out in percent-02.   A refer-
 ence concentration  of  oxygen,  however,  must  be  established  for this
 format.
      The  primary  disadvantages associated with concentration  standards
 are:  (1) a standard could be circumvented by dilution of exhaust gases
 discharged Into the atmosphere, which lowers the concentration of the
 emissions but does not reduce the total mass emitted, and (2) a concen-
 tration standard could penalize high efficiency engines because more
efficient engines  generally discharge higher concentrations  of NO
                                                                 x
                                  9-69

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emissions due to higher operating temperatures and pressures as mentioned
above (although the mass emission rate may be the same as a lower effi-
ciency engine).  A concentration standard based on low efficiency engines,
therefore, could penalize high efficiency engines.  Both these problems,
however, can be overcome through the use of appropriate "correction"
factors.
     Since the percent  reduction format  1s Impractical, and the problems
associated with the enforcement of mass  standards  (mass per unit energy
output or Input) appear to outweigh the  benefits,  the concentration for-
mation was selected as  the format for  standards  of performance  for  large
stationary Internal combustion  engines.
     As  mentioned  above, because a concentration standard  can  be circum-
vented  by dilution of the  exhaust gases, measured concentrations must
be expressed relative to some fixed dilution level.   For combustion
processes,  this  can be accomplished by correcting measured concentra-
 tions  to a  reference  concentration  of oxygen.  The oxygen concentration
 1n the exhaust gases  1s related to  the excess (or dilution) air.
 Typical  oxygen concentrations 1n large-bore Internal  combustion engines
 can range from 8 to 16 percent but  are normally about 15 percent.
 Thus,  referencing the  standard to a typical level of 15 percent oxygen
 would prevent circumvention by dilution.  (Section 9.6 discusses the
 correction  factor for  adjusting measured NOX concentrations to an
 oxygen  concentration of 15 percent).
      As also mentioned above,  selection of  a concentration format
 could penalize high  efficiency  internal combustion engines.  These
 highly  efficient  engines generally operate  at  higher temperatures  and
                                  9-70

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   pressures,  and as a result discharge gases with higher N0x concentrations
   than  less efficient engines,  although both engines'  brake-specific mass
   emissions could  be the  same.   Thus,  a concentration  standard  based on
   low efficiency engines  could  effectively  require more  stringent  con-
   trols  for high efficiency  engines.   Conversely, a concentration  stan-
   dard based on  high  efficiency  engines would require no controls.
   Consequently, selecting a concentration format for standards of per-
   formance requires an efficiency factor to permit higher N0y emission
                                                            A
  from more efficient engines.
       The Incentive for manufacturers  to Increase engine efficiency 1s
  to lower engine fuel consumption.   Therefore,  the  objective of an effi-
  ciency  adjustment factor should be  to give an  emissions credit for the
  lower fuel consumption of more  efficient  internal combustion engines.
  Since the fuel  consumption  of  internal combustion engines varies  linearly
  with efficiency,  a  linear adjustment  factor  is selected to  permit
  increased NOX emissions  from highly efficient internal combustion
 engines.  A linear efficiency adjustment factor also effectively limits
 NOX emissions to a constant mass emission rate per unit of power output.
      The efficiency adjustment  factor  needs to  be referenced to a
 baseline efficiency.   Most  large existing  stationary  internal combustion
 engines  fall  in  the range of 30  to 40  percent efficiency.  Therefore,
 35 percent is  selected as the baseline efficiency.  The  efficiency  of
 internal  combustion  engines  is usually expressed  in terms of heat  rate.
The heat  rate of engines  operating at  35 percenc en iciency  is about
7270 Btu/hp-hr.  Thus, the following linear adjustment factor is selected
to permit increased NOX emissions from  high efficiency large stationary
                                   9-71

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internal  combustion engines:
                                       7270
where:
                              xa = x
                               a        Y
          X  • Adjusted NO  emissions permitted at 15 percent oxygen, ppmv
           a              x
          X  = NO  emission limit specified in the standards at 15 percent
                 A
               oxygen on a dry basis
          Y  = LHV heat input per unit of power output (Btu/hp-hr)
          NOTE:     Above adjustment is made at standard atmospheric
                    conditions of 29.92 m Hg, 85°F, and 75 grains moi-
                    sture per pound of dry air.
      This efficiency  adjustment  factor permits a  linear increase  in NOX
 emission with  increased efficiencies above 35 percent.  This adjustment
 would not be used  to  adjust  the  emission  limit downward for  internal
 combustion  engines with efficiencies of  less  than 35  percent.   This
 efficiency  adjustment factor also  applies only to the 1C  engine itself
 and not the entire system of which the  engine may be  a part.   Since
 Section 111 of the Clean  Air Act requires the use of  the  best  system of
 emission reduction in all cases, this  precludes  the application of the
 efficiency adjustment factor to an entire system.  For example, 1C
 engines with waste heat recovery may have a higher overall efficiency
 than the 1C engine alone.  Thus, the application of the efficiency
 adjustment factor to the entire system would permit greater NOX emissions
 because of the system's higher overall efficiency, and would not necessarily
 require the use of the best demonstrated system  of emission reduction on
 the  1C engine.
                                    9-72

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   9.6  SELECTION OF NUMERICAL EMISSION LIMITS
   Overall Approach
        As mentioned earlier, It 1s difficult to select , specific NO
   emission limit which ,11  1C engines could meet primarily through the
   use of ignition retard or air-to-fuel  ratio change.   Because of In-
   herent  differences  among  various  1C engines with  regard  to  uncontrolled
   NOX  emission  levels,  there exists  a rather  large  variation  within  the
   data and Information  Included  1n the SSEIS  concerning controlled NOX
   emission levels.  Generally speaking, engines with relatively low   "
  uncontrolled NOX emissions achieved low controlled NOX emission levels.
  and engines with high uncontrolled NO,  emission levels achieved relatively
  high controlled NOX  emission levels. Consequently,  the following
  alternatives were  considered for  selection of the  numerical  concentra-
  tion  emission  Hmlts  based on a 40  percent reduction  1n NOX  emissions:
       1.   Apply  the 40  percent  reduction to  the highest observed
           uncontrolled  NOV  emission  level.
                          *\
      2.    Apply the 40  percent  reduction to a sales-weighted average
           uncontrolled NO  emission level.
                          /\
      3.    Apply the 40 percent reduction to this sales-weighted average
           uncontrolled NOX  emission  level  plus one  standard  deviation.
      The  highest  observed uncontrolled NOX  emission levels for dlesel,
dual-fuel and gas engines discussed  In alternative  I above can  be  found
in Figures 4-49{.-c).  respective^.   The uncontrolled  levels  for dual-
fuel engines are generally  lo«er than those for dlesels, which are gen-
erally lower than those for gas engines.   The highest uncontrolled
                                 9-73

-------
levels for each fuel type are as follows:   (1) gas, 29 g/hp-hr, (2)
dual-fuel, 15.0 g/hp-hr, and (3) diesel, 19 g/hp-hr.
     The sales-weighted uncontrolled N0¥ emission levels which are used
                                       A
as the base levels in the second alternative are discussed in Section
4.3.4.  It was noted that uncontrolled NOX emission levels vary among
both engines of the same fuel type and of different fuels (even after
considering the effects of ambient conditions and measurement methods).
Therefore, an average uncontrolled level was determined by applying a
sales-weighting to each manufacturer's average uncontrolled NOX emis-
sions for engines of each fuel  type (see Section 4.3.4).  The  sales-
weighting, based on horsepower  sold, gives more weight  to those engine
models which have the highest sales.  The sales-weighted average uncon-
trolled N0¥ emission level for  each engine fuel type  are as follows:
          J\
(1)  gas,  15 g/hp-hr, (2) dual-fuel, 8 g/hp-hr, and  (3)  diesel, 11  g/hp-
hr.
      The  third  alternative  incorporates a  "margin  for engine  variabili-
ty"  by  adding  one standard deviation  to the  sales-weighted average
uncontrolled  NO  emission  level and then  applying  the 40  percent  reduc-
                ^
tion.   Standard deviations  discussed  were  calculated  from  the uncontrolled
NO  emission  data  included  in  the SSEIS,  assuming  it  had  a normal  distri-
   J\
bution.   A  subsequent  statistical evaluation of the data  indicated that
 this assumption was valid  (see Appendix C  for a complete  discussion).
The  standard  deviations for each engine fuel type  are as  follows:   (1)
 gas, 4 g/hp-hr, (2) dual-fuel,  3.2 g/hp-hr and (3) diesel,  3.7 g/hp-hr.
      The standard deviation of the uncontrolled NOX emission data base
 is relatively large compared to the sales-weighted average uncontrolled

                                  9-74

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  Internal combustion engines:
                               x  - y   727°
                               Aa " *   ~
 where:
           Xg • Adjusted N0x emissions permitted at 15 percent oxygen, ppmv
           X  = NOX emission limit specified in the standards at 15 percent
                oxygen on a dry basis
           Y  = LHV heat input per unit of power output (Btu/hp-hr)
           NOTE:     Above adjustment is made at standard atmospheric
                     conditions of 29.92 m Hg,  85°F,  and 75 grains moi-
                     sture per pound  of dry air.
      This efficiency adjustment  factor permits a linear increase in NO
                                                                       A
 emission with increased efficiencies  above 35  percent.   This adjustment
 would not be used  to adjust the  emission  limit downward  for internal
 combustion  engines  with efficiencies  of less than  35  percent.   This
 efficiency  adjustment  factor also applies  only to  the  1C engine  itself
 and  not  the  entire  system of which the  engine  may  be  a  part.  Since
 Section  111  of  the  Clean Air Act  requires  the  use  of  the best system  of
 emission  reduction  in  all cases, this precludes  the application  of  the
 efficiency adjustment  factor to an entire  system.  For example,  1C
 engines with waste  heat recovery may have  a higher overall efficiency
 than  the  1C engine  alone.  Thus, the application of the efficiency
adjustment factor to the entire system would permit greater NO  emissions
                                                              n
because of the system's higher overall efficiency,  and would not necessarily
require the use of the best demonstrated system of emission reduction on
the 1C engine.
                                   9-72

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concentration emission limit.
     The first alternative 1s  to apply the 40 percent reduction to the
highest uncontrolled NOX emission level within a fuel category,  For
example, Figure 4-49(c), which summarizes NOX emission reductions
achieved by gas engines, lists 29 g/hp-hr as the highest uncontrolled
NOX emission  level.  The application of a 40 percent reduction would
lead  to  an emission  level  of  about  17  g/hp-hr,  As  Illustrated  1n
Figure 9-16,  1f  this level were  selected  as  a  standard of  performance,
99 percent of production  gas  engines  could  easily meet the emission
 limit by reducing emissions by 40 percent or less.   However,  69 percent
 of production engines would not have to reduce NOX  emissions  at all.
 Only one percent of production engines would have to reduce NO, emissions
 by more than 40 percent.
      The second alternative  1s to  apply the 40 percent reduction to the
 sales-weighted average uncontrolled NOX emission level.    For example,
 the  sales-weighted  average uncontrolled NOX level  for gas engines 1s 15
 g/hp-hr.  The application of a  40  percent  reduction would lead  to an NOX
 emission level  of 9 g/hp-hr. As illustrated  in Figure 9-16,  if this
  level  were  selected as a standard  of performance,  50  percent of produc-
  tion gas  engines could meet  the standard with 40  percent or  less reduc-
  tion in NOX emissions.  However, 50 percent of production gas engines
  would be required to reduce  NOX emission by greater than 40 percent.
  Only seven  percent of production  gas engines would not have to reduce NOX
   emissions at all.
       The third  alternative  is  to  base the  standard on a  40 percent
   reduction  in NO   emissions  from the  sales-weighted average  uncontrolled
                  X
   N0¥ emission level  plus  one standard deviation.   For example,  the  sales-
     ^
                                     9-76

-------
   weighted  average  uncontrolled  NO,  emission  level  for gas  production  gas
   engines 1s 15 g/hp-hr and  the  standard deviation  of  the production gas
   engine data base  (Appendix C)  Is 4 g/hp-hr.  Thus, the appl,cation of a
   40 percent reduction to the sum of these two values would lead to an
   emission level  of 11 g/hp-hr.   As Illustrated 1n Figure 9-16, 1f this
   level were selected as  a standard of performance,  84 percent of the pro-
   duction  gas  engines would  not  have  to reduce N0X emission  at all.   Only
   16  percent of the  production gas  engines  would  have  to reduce NOX
   emissions  by more  than 40  percent.
        Similarly, applying the three alternatives  to dual-fuel engines
        s results similar to those for gas engines.  The  highest uncontrolled
  NOX emission level  from a dual  fuel  engine is ,5 g/hp-hr.   The appli-
  cation of a 40  percent reduction would lead to an emission  level  of 9
  9/hp-hr.   ,f  this level were selected as  a standard of performance,  98
  percent of  production dual-fuel  engines could easily meet the emission
  limit  by  reducing NO, emissions  by 40  percent or  less.  However, 62
  percent would have  to achieve no reduction  In NO, emissions.  Only two
  percent of production engines would have to reduce NO,  emissions by more
 than 40 percent.
      The sales-weighted average  uncontrolled NO,  emission level for
 dual-fuel  engines  is 8 g/hp-hr.   The  application  of  a  40 percent reduc-
 tion  would lead to a NO, emission level of  about  5 g/hp-hr.   If this
 leve, were selected  as a standard of  performance,  64 percent of  the
production dual-fuel  engines could meet the standard by  reducing NO
en-issions 40 percent or less.  Only ,8 percent of the production dull-
fuel  engines  would not have to reduce  NO,  emissions at all.   Also,  46
                                 9-77

-------
percent of the production dual-fuel  engines would be required to reduce
NO  emissions by greater than 40 percent.
     The standard deviation of the production dual-fuel engine data base
1s 3.2 g/hp-hr.  Thus, the application of a 40 percent reduction to the
sum of the sales-weighted average uncontrolled NOX emission  level  (8
g/hp-hr) and  the standard deviation  (3.2 g/hp-hr) would lead to  an
emission level  of 7  g/hp-hr.   If  this  level were selected  as a  standard
of performance,  87  percent  of  the production  dual-fuel  engines  could
easily meet  the emission limit by reducing emissions by 40 percent or
 less.   However, 48  percent of  the production  gas engines  would  not have
 to reduce N0y emission at all.  Only 13 percent of the production gas
             A
 engines would have to reduce NOX emissions by more than 40  percent.
      Finally, the application of the three alternatives to  diesel engines
 also yields  very similar results.  The highest  uncontrolled NOX emission
 level from a diesel  engine  is 19 g/hp-hr.  The  application  of  a 40
 percent reduction would lead  to  in  an  emission  level  of  about  11  g/hp-
 hr.   If  this level  were selected as a standard  of  performance,  98 percent
 of production  diesel engines  could  easily meet the emission limit by
  reducing  emissions by 40 percent or less.   However, 40 percent would
  have to achieve no reduction  in NOX emissions.  Two percent of production
  engines would be required to reduce NOX emission by more than 40 percent.
       The sales-weighted average uncontrolled NOX emission  level for
  diesel engines is  11 g/hp-hr.  The application of  a  40 percent reduction
  would lead  to  a NOX emission level of  about 7  g/hp-hr.   If this  level
   were  selected  as  a standard  of  performance, 56 percent  of  the  production
   diesel  engines could meet the  standard by reducing NO,  emissions 40
                                     9-78

-------An error occurred while trying to OCR this image.

-------
percent or less.   Only 14 percent of the production diesel  engines would



not have to reduce NO  emissions at all.  However, 44 percent of the
                     X


production diesel  engines would be required to reduce NO  emission by
                                                        A


greater than 40 percent.



     The standard deviation of the production diesel engine data base 1s



3.7 g/hp-hr.  Thus, the application of a 40 percent reduction to the sum



of the sales-weighted uncontrolled NOX emission level (11 g/hp-hr) and



the standard deviation (3.7 g/hp-hr) would lead to a NOV emission level
                                                       A


of 9 g/hp-hr.  If this level were selected as a standard of performance,



86 percent of the production diesel engines could easily meet the emis-



sion limit by reducing emissions by 40 percent or less.   However, 29



percent of the production gas engines would not have to reduce NOX



emissions at all.   Only 14 percent of the production gas engines would



have to reduce NOV emissions by more than 40 percent.
                 A


     Table 9-9 presents a summary of the statistical analysis of stan-



dards of performance based on each alternative for each engine fuel



type.  If standards of performance were based on Alternative I, essen-



tially all engines could achieve the emission limit by reducing NOX



emissions 40 percent or less.  A significant reduction in NOX emissions



would not be achieved, however, since 50 to 70 percent of the 1C en-



gines would not have to reduce NO  emissions at all.  If the standards
                                 A


of performance were based on Alternative II, about 50 percent of the



1C engines  (in all categories) would have to reduce NOX emissions by



greater than 40 percent.  Less than 10  percent would not have to reduce



NO  emissions at all.  Thus, this  alternative would achieve a signifi-
  A


cant reduction in  NO  emissions from new sources.   If standards of
                    A




                                  9-80

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   TABLE 9-9.   SUMMARY  OF STATISTICAL  ANALYSES  OF  ALTERNATE
               EMISSION LIMITS
                        GAS ENGINES
          Alternative
Standard
Percent required to apply
less than or equal to
40 percent control
17
99

9
50

11
84

   Percent required to do
   nothing
   Percent required to apply
   more  than 40 percent con-
   trol
   1    50
                    DUAL-FUEL  ENGINES
         Alternative
         —
          Standard
           	   •••    • 	  I l.l_
 Percent required to apply
 less  than or equal  to
 40  percent control
	"^    •"•"'   '     	 	
 Percent required to do
 nothing
98   56
Percent  required  to  apply
more than'40 percent con-
trol
                 18
  16
Percent required to apply
less than or equal to
40 percent control
f— 	 . — . 	
Percent required to do
nothing
Percent required to apply
more than 40 percent con-
trol
I 	 ••••Bin 	 	 .... -.- -
DIESEL ENG
'""•""—'—•"' 	 -!-..• 	 	 ^_
Alternative
~
Standard
98 54
62 18
2 46
INES
I II
i.iii.ni. __.„—,, i i •__,.».„..,,..
11 7
87
48
13

III
i,.l
9
86
               29
               14
                        9-81

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performance were based on Alternative III, the results would be similar



to those achieved with Alternative I.  About 85 percent of engines



could easily meet the standards by reducing N0¥ emissions by less than
                                              A


40 percent.  About 20 to 30 percent of 1C engines would not have to



reduce NOY emissions at all and about 15 percent of 1C engines would
         n


have to reduce NO  emissions by more than 40 percent.
                 A


     In light of the high priority discussed earlier which has been



directed toward reducing NOV emissions and the significance of 1C
                           A


engines 1n terms of their contribution to NOX emissions from stationary



sources, the second alternative was chosen for selecting the MOV
                                                               A


emission concentration limit.   This approach will achieve the greatest



reduction 1n NOX emissions from new 1C engines.



Selection of Limits



     A concentration (ppm) format was selected for the standards.   Con-



sequently, the brake-specific NOX emission limits corresponding to the



second alternative for selecting numerical emission limits (I.e.,  gas -



9 g/hp-hr; dual-fuel - 5 g/hp-hr; dlesel  - 7 g/hp-hr) must be converted



to concentration limits (corrected to 15 percent oxygen).  This may be



done by dividing the brake-specific volume of NOX emissions by the brake



specific total exhaust gas volume.  Determining the brake-specific volume



of NOV emissions is straightforward.   Determining the brake-specific
     A


total exhaust gas volume is more complex, in that the brake-specific



exhaust flow and the exhaust gas molecular weight are unknown.  Knowing



the fuel heating value and composition,  the brake-specific fuel consumption,



and assuming 15 percent excess air, however, defines these unknowns.



(The complete derivation is explained in detail in Appendix C-5).
                                 9-1

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  Combining these factors leads to the following conversion factor:
                                          (ir)x  BSNO>
NO	1^6 /  *  —"x
                             x
                              15
         16.6 + 3.29 Z!
                                                   x   BSFC
                                      12.0  +  Z
                                                 fl
 where:
      NOX   a NOX concentration ppmv  corrected to 15-percent oxygen
              on a dry basis.
      BSNOX - Brake-specific NOX emission, g/hp-hr.
      BSFC  « Brake-specific fuel consumption, g/hp-hr.
      Z     - Hydrogen/Carbon ratio of the fuel.
      The numerator 1s the brake specific volume of NOY emissions multl-
            6
 pi led by 10  in order to convert the decimal equivalent to ppm.   In the
 denominator,  the brake-specific total dry exhaust gas volume with 15
 percent excess  oxygen 1s expressed  as a function of the fuel's hydrogen/
 carbon  ratio  and the  brake-specific fuel  consumption.   The fuel  consump-
 tion  has  been converted  from Btu/hp-hr to  g/hp-hr using the fuel's
 lower heating value (LHV).
      For  natural gas, a  hydrogen to carbon (H/C)  ratio  of  3.5  and an LHV
 of 20,000 Btu/lb was  assumed.  Diesel  ASTM-2 has  a  H/C  ratio of  1.8 and
 an LHV of 18,320 Btu/lb.
     Using the above equation,  plots of BSNOX versus ppm were generated
for each fuel type.  The uncontrolled values of BSNO  and BSFC were
                                                    /\
used for each engine,  producing plots similar to Figure 9-17.  As
shown, agreement between this equation and actual emission data relating
                                 9-83

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 NOX emissions concentrations  to  BSNOX  1s  excellent,   Comparison  of this
 conversion factor with available  raw data also  shows  excellent agree-
 ment (see Appendix C.5).  Applying this conversion factor to the brake-
 specific emission limits associated with the second alternative for NO
                                                                       o
 emission limits leads to the NOX concentration emission limits for
 large stationary Internal combustion engines summarized 1n Table 9-10.
      These emission limits have been rounded upward to the nearest 100
 ppm to Include a "margin" to allow for source variability.   The standard
 for dlesel  engines  has also bean applied to  dual-fuel  engines.   If a
 separate emission  limit had been selected  for dual-fuel  engines,  the
 corresponding  numerical  NOX concentration  emission limit would  be 400
 ppm.   Sales of dual-fuel  engines  have  ranged from 17  to  95 units  annually
 over the past  five years, with a  general trend of decreasing  sales.  Dual-
 fuel engines serve the same  applications as  diesel  engines, and new
 dual-fuel engines will  likely  operate primarily  as  diesel engines due
 to  increasingly  limited natural gas supplies.  Thus, combining of
 dual-fuel engines with diesel engines for standards of performance will
 have little adverse impacts and will simplify enforcement of the standards
of performance.
TABLE 9-10.   NUMERICAL NO  CONCENTRATION EMISSION LIMITS FOR LARGE
             STATIONARY INTERNAL COMBUSTION ENGINES
                    Engine
                   •••••^
                    Gas
                    Diesel/dual-fuel
     x
Emission
  Limit
   700 ppm
   600 ppm
                                 9-85

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     As discussed in Section 4.2.1,  the effect of ambient atmospheric


conditions on NO  emission from large stationary internal combustion
                A

engines can be significant.  Therefore, to enforce the standards uni-


formly, NO  emissions must be determined relative to a reference set of
          A

ambient conditions.  All existing ambient correction factors were


reviewed that could potentially be applied to large stationary internal


combustion engines  to correct NOX emissions to standard conditions.  A


detailed discussion of  this review is  presented  in Section 4.2 and


Appendix C.2.

     The correction factors that were  selected for both  spark  ignition


 (SI) and compression  ignition  (CI) engines are presented  in Table  4-2,


which  is  reproduced below  as Table 9-11.  For the compression  ignition


 engines  (i.e.,  diesel  and  dual-fuel),  a single correction factor for


 both temperature and  humidity  was  selected.   Constants  for use in  this


 correction factor, which have  been  experimentally derived, are summarized


 in the table.   For spark ignition  engines (i.e., gas),  separate correc-


 tion factors were selected for humidity and  temperature, and measured


 NO  emissions are corrected to reference ambient conditions by multiplying
   A

 these two factors together.  No correction factor was selected for


 changes in ambient pressure, because  no generalized relationship could


 be determined for  the  very limited data that were available.  These


 correction factors represent the general effects of ambient temperature


 and relative humidity  on  NOX emissions, and will be used  to adjust


 measured  NO  emissions during any performance test to determine compli-
            A

 ance  with the  numerical emission limit.
                                    9-86

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TABLE 9-11   EXISTING INTERNAL COMBUSTION ENGINE AMBIENT CORRECTION
             FACTORS FOR APPLICATION TO LARGE-BORE ENGINES
    Fuel
                 Correction Factor
Diesel and
Dual-Fuel
         + 0.00235(H - 75) + 0.00220 (T - 85))
Gas
K - (KH) (KT)
                              KH» 0.844 + 0.151 () +0.075
                                     - (T - 85)(0.0135)
where:
          H • observed humidity, grains f^O/lb dry air
          T a observed inlet air temperature, °F

     Since the recommended factors may not be applicable to certain
engine models, as an alternative to the use of these correction factors,
engine manufacturers, owners, or operators may elect to develop their
own ambient correction factors.   All such correction factors, however,
must be substantiated with data and then approved for use by EPA in
determining compliance with the NOX emission limits.  The ambient
correction factor will be applied to all performance tests, not only
those in which the use of such factors would reduce measured emission
levels.
                                 9-87

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     As discussed  In the Standards Support and Environmental  Impact
Statement, "Proposed Standards of Performance for Stationary  Gas Turbines,"
EPA-450/2-77-017a, the contribution to N0¥ emissions by the conversion of
                                         /\
fuel-bound nitrogen in heavy fuel to N0¥ can be significant for stationary
                                       A
gas turbines.  The organic NOV contribution to total gas turbine NO
                             «                                     x
emission is complicated by the fact that the percentage of fuel-bound
nitrogen converted to NOX emissions varies with the fuel-bound nitrogen
level. Figure 9-18 illustrates the variation in conversion of fuel-
bound nitrogen to NOX emissions with the fuel-bound nitrogen  level of
the fuel.  While this figure is based on very limited data, it indicates
that the percentage of fuel-bound nitrogen converted to NOY emission
                                                          A
decreases as the fuel-bound nitrogen level increases.  Below  a fuel-
bound nitrogen level of about 0.05 percent, essentially 100 percent of
the fuel-bound nitrogen is converted to NOV.   Above a fuel-bound nitro-
                                          A
gen level of about 0.4 percent, only about 40 percent is converted to
NOV.  Using Figure 9-18, an estimate of the effect on controlled NO
  *                                                                x
emission levels of firing fuels with various fuel-bound nitrogen levels
can be made.
     As discussed in the Standards Support and Environmental  Impact
Statement,  "Proposed Standards of Performance for Stationary Gas
Turbines,"  EPA-450/2-77-017a, assuming a fuel with 0.25 weight percent
fuel-bound  nitrogen (which allows approximately 50 percent availability
of domestic heavy fuel  oil),  controlled NOX emission would increase by
about 50 ppm due to the contribution to N0¥ emissions of fuel-bound ni-
                                          A
trogen.   In gas turbines, this contribution was significant when compared
to the proposed emission limit of 75 ppm.   It can be assumed  that the
                                 9-1

-------An error occurred while trying to OCR this image.

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conversion of fuel-bound nitrogen to NO  In large internal combustion
                                       /\
engines is similar to that in gas turbines.  Specifically, in both
facilities, fuel and air combustion occurs at high temperatures and at
similar sto1ch1ometr1c conditions.  Based on this assumption, the
contribution of fuel-bound nitrogen to NOX emissions (I.e., 50 ppm), is
likely to be very small  (I.e., approximately 10 percent).  Given that
the emission limits have been rounded upward to the nearest 100 ppm and
the potential contribution of fuel-bound nitrogen to NOX  emissions  is
very  small, no  allowance has been  included for the fuel-bound nitrogen
content of  the  fuel  in  determining  compliance with the  standards of
performance.
9.7   SELECTION  OF COMPLIANCE TIME  FRAME
      Manufacturers  of large-bore 1C engines  are  generally committed to
a particular  design approach  and,  therefore,  conduct  extensive  research,
development,  and  prototype testing before releasing  a new engine  model
 for sale.   Consequently, these  manufacturers will  require some  period
 of time to modify or reoptimize and test 1C engines  to meet standards
 of performance.  As discussed in Section 6.3, the estimated time span
 between the decision by a manufacturer to control  NOX emissions from an
 engine model  and start of production of the first controlled engine is
 about 15 months for any of the  four demonstrated emission control tech-
 niques.  With  their present facilities, however, testing can typically
 be conducted on only two  to three  engine models at a time.  Since most
 manufacturers  produce  a number  of  engine models, additional time  is
  required before  standards of performance  become effective.  In addition,
  a number of manufacturers produce  their most popular  engine models  at

                                   9-90

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  a  fairly  steady  rate  of  production  and  satisfy  fluctuating  demand  from
  Inventory.  Consequently, additional  time  Is  necessary  to allow manufac-
  turers to sell their  current  Inventory  of  uncontrolled  1C engines
  before they must comply with  standards  of  performance.
      It 1s estimated  that about 30 months  delay 1n the  effective date
  of the standard  1s appropriate to allow manufacturers time  to comply
 with the proposed standards.  In addition, 1n light of  the  stringency
 of the standards (I.e., many models will have to reduce NO  emissions
                                                           A
 by more than 40 percent), this time period provides the flexibility of
 manufacturers to develop and use combinations of the control techniques
 upon which the standards are based or other control techniques.   Con-
 sequently, 30 months from the date of proposal 1s selected as the delay
 period  for Implementation of these standards  on  large stationary Inter-
 nal  combustion engines.
 9.8  MODIFICATION/RECONSTRUCTION
      A  discussion of the  modification  and  reconstruction regulations
 and  how they  pertain  to  the  Internal combustion  engine Industry  can be
 found 1n Chapter  5.   Since few modified  or  reconstructed Internal
 combustion engines are anticipated,  the  modification  and reconstruction
 regulations will  have  little  impact.   The demonstrated NO  reduction
                                                         n
 techniques, however, are as effective  in reducing emissions  of NO   from
                                                                 A
 modified or reconstructed Internal combustion  as from  new Internal
 combustion engines.   Thus, modified or reconstructed  internal combustion
 engines merit no special allowance in  the standards of performance.
 9.9  SELECTION OF PERFORMANCE TEST METHOD
     A performance test method 1s required to determine whether an
engine complies with the standards of performance.   Reference Method
                                  9-91

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20, "Determination of Nitrogen Oxides,  Sulfur Dioxide,  and Oxygen
emissions from Stationary Gas Turbines," 1s proposed as the performance
test method for 1C engines.   Reference Method 20 has been shown to
provide valid results.  Consequently, 1t was decided that rather than
a totally new reference test method being developed, Reference Method
20 would be modified for use on 1C engines.
     The changes and additions to Reference Method 20 required to make
1t applicable for testing of Internal combustion engines include (by
section):
     1.       Principle and Applicability.  Sulfur dioxide measurements
are not  applicable for internal combustion engine testing.
     6.1      Selection of a sampling site and  the minimum number of
traverse points.
     6.11     Select a sampling site located  at least  five stack diameters
downstream of any  turbocharger exhaust,  crossover junction, or recircu-
lation take-offs  and upstream  of  any dilution air inlet.   Locate  the
sample site one meter or  three stack diameters  (whichever 1s  less)  upstream
of the gas discharge to  the  atmosphere.
      6.1.3    A preliminary  02 traverse is not necessary.
      6.2      Cross-sectional  layout and location of traverse points
 use a minimum of 3 sample points  located at positions  of 16.7, 50 and
 83.3 percent of the stack diameter.
      6.3.1.4  Record the data required on the engine operation record
 on Figure 20.6 of Reference Method 20.  In addition, record (a) the
 intake manifold pressure; (b) the intake manifold temperature; (c) rack
 position;  (d) engine speed; and  (e) Injector or spark fuming.  (The
 water or  steam injection rate 1s not applicable to  internal combustion
 engines.)
                                   9-92

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     NO  emissions measured by Reference Method 20 will be affected by
       A
ambient atmospheric conditions.  Consequently, measured NOX emissions
would be adjusted during any performance test by the ambient condition
correction factors discussed earlier, or by custom correction factors
approved for use by EPA.
     The performance test may be performed either by the manufacturer
or at the actual user operating site.  If the test is  performed at the
manufacturer's facility, compliance with that performance test will be
sufficient proof of compliance by the user as long as  the engine operating
parameters are not varied during user operation from the settings under
which testing was done.
9.10 SELECTION OF MONITORING REQUIREMENTS
     To  provide a means  for enforcement  personnel to ensure  that an
emission control  system  installed to comply with  standards of  performance
is properly  operated and maintained, monitoring requirements are generally
included  in  standards of performance.   For stationary  internal combustion
engines,  the most straightforward means  of ensuring  proper operation
and  maintenance would be to monitor  NOX  emissions released to  the
atmosphere.
      Installed  costs, however,  for continuous NOX monitors are approxi-
mately  $25,000.(32^  Thus,  the cost  of  continuous NOX  emission monitoring
 is considered  unreasonable for 1C engines  since most large  stationary
 1C engines  only cost from  $50,000 to $3,000,000  (I.e., 1000  hp gas
 production  engine and 20,000  hp electrical  generation  engine).
      A more simple and  less  costly method  of monitoring is measuring
 various engine operating parameters  related  to NOX emissions.   Conse-

                                9-93

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 quently,  monitoring  of  exhaust  gas  temperature was  considered  since
 this  parameter  could be measured just  after  the  combustion  process
 where NOX 1s  formed.  However,  a thorough  Investigation of  this  approach
 showed no simple  correlation between NOX emissions  and exhaust gas
 temperature.
      A qualitative estimate of  NOX  emissions, however, can  be  developed
 by measuring  several  engine operating  parameters simultaneously, such
 as spark  Ignition or fuel  Injector  timing, engine speed, and a number
 of other  parameters.    '   These parameters are typically measured at
 most  Installations and  thus should  not Impose an additional cost Im-
 pact.   For these  reasons,  the emission monitoring requirements Included
 1n the  proposed standards  of performance require monitoring various
 engine  operating  parameters.
      For  dlesel and  dual-fuel engines, the engine parameters to be
 monitored are:  (1)  Intake manifold temperature; (2) Intake manifold
 pressure; (3) rack position; (4) fuel Injector timing; and  (5) engine
 speed.  Gas engines would  require monitoring of:   (1) Intake manifold
 temperature;  (2) Intake manifold pressure; (3) fuel  header pressure;
 (4) spark timing; and (5) engine speed.
     Another parameter that could be monitored for gas engines 1s the fuel
 heat value, since 1t can affect NOX emissions significantly.  Because
of the high costs of a fuel heating value monitor,  and the fact that many
 facilities can obtain the lower heating value directly from the gas
supplier, monitoring of this parameter would not be  required.
     The operating ranges for each  parameter over which the engine
could operate and 1n which the engine could comply with the emission limit
                                 9-94

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would be determined during the performance test.  Once established, these
parameters would be monitored to ensure proper operation and maintenance of
the emission control techniques employed to comply with the standards of
performance.
     For facilities having an operator present everyday, these oper-
ating parameters would be recorded dally.  For remote facilities where an
operator 1s not present every day, these parameters would be recorded weekly.
The owner/operator would record the parameters, and 1f these parameters
Include values outside the operating ranges determined during the
performance test, a report would be submitted to the Administrator on a
quarterly basis Identifying  these periods as excess emissions.  Each
excess emission report would Include the operating ranges for each
parameter as determined during  the performance  test, the monitored
values for  each parameter, and  the ambient air  conditions.
                                  9-95

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                          REFERENCES  FOR  CHAPTER  9


(1)   Bartok,  W.,  et al.  System Study  of Nitrogen  Oxide Control Methods for
Stationary sources, Final  Report.   Volume II.   National Air Pollution
Control Administration.  NTIS Report No. PB-192-789.  1969.

(2)   McGowin, C.R. Stationary Internal Combustion Engines in the United
States.  Environmental Protection Agency. EPA-R2-73-210.  April 1973.

(3)   Brown, R.A., H.B. Mason, and R.J. Schreiber.  Systems Analysis
Requirements for Nitrogen Oxide Control of Stationary  Sources.
Environmental Protection Agency.  EPA-650/2-74-091.  June 1974.

(4)   Preliminary Environmental Assessment of the Application  of Combustion
Modification Technology to Control Pollutant Emissions  from Major
Stationary Combustion Sources.  Volume II-Technical Result.   Acurex
Corporation.  Report TR-77-28.  pp.  5-46 February  1977.

(5)  Computer printout of Nationwide Emissions Report,  National Emissions
Data System, as  of  January  10,  1975.   Obtained from the Monitoring  and
Data Analysis Division, OAQPS,  U.S.  Enviornmental  Agency.

 (6)  Youngblood,  S.B. and G.R.  Offen.  Acurex  interoffice Memorandum.
 Emissions  Inventory of  Currently  Installed  Stationary Reciprocating
 Engines.   September 23,  1975.

 (7)  Op.  Cit.,  Reference  5.

 (8)  Hopper, T.6. and W.A.  Marrone.   Impact of New Source Performance
 Standards on 1985 National  Emissions from Stationary Sources.  The
 Research Corporation of New England.  October  24, 1975.

 (9)   Habegger,  L.J., et.al.  Priorities and Procedures for Development of
 Standards of Performance for New Stationary Sources of Atmospheric
 Emissions.  Argonne National Laboratory.  May 1976.

 (10)  Air Quality Criteria for Hydrocarbons.  National Air Pollution
 Control Administration.  AP-64.  Washington, D.C. 1970.

 (11)  Goodwin, D.R., EPA/Emission Standards and Engineering  Division.
 Request for Information. June  16, 1976.

 (12)  Snyder, W.E.  (Waukesha)  and D.R. Goodwin  (EPA)  Private
 Communication.   July 20, 1976.
                                      9-96

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                                                  (EPA)'
              '1976:  (GMC) ami D'R- S0°dw1n -
                                    G00 the Files, Meeting Ronnn- .
                          Of I «r / O •

                                  9-97

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                                  APPENDIX A
                       EVOLUTION OF PROPOSED STANDARDS

        This study to develop proposed standards of performance for new
 stationary reciprocating internal combustion engines began on June 24,
 1974.  In March 1976, draft Standards Support Document and Environmental
 Impact Statement (SSEIS) was presented to the National A1r Pollution Control
 Techniques Advisory Committee (NAPCTAC).   This draft had been prepared
 by the Aerotherm Division of Acurex Corporation, Mountain View,  California
 under Contract 68-02-1318,  Task  No.  7.   Randy  Seiffert,  Standards  Support
 Criteria Pollutants  Section,  Industrial  Studies  Branch,  Emission Standards
 a,nd Engineering Division (ESED),  Office  of Air Quality Planning  and  Standards
 (OAQPS),  U.S.  EPA, was  the  Project  Engineer.   A  revised  draft SSEIS  was
 prepared  by Acurex/Aerotherm  under  Contract 68-02-2530 beginning in  October
 1976,  under the direction of  Mr.  Douglas  Bell  (Project Engineer) and
 Mr.  Fred  Porter (Section Chief), Standards Development Branch, Regulations
 Preparation Section Branch, ESED/OAQPS, U.S. EPA.  Preliminary work  for this
 revision  was accomplished under Contract  68-01-3158, Task 14, beginning in
 July 1976,  under the direction of Mr. John McDermon, Standards Development
 Branch, ESED/OAQPS, U.S. EPA.
       The  first step 1n this investigation was to Initiate a two-part
 literature survey, one part being directed toward technical questions
and the other toward a characterization of the Industry.   The technically-
oriented survey sought Information on the best control  technologies available
                                        A-l

-------
for stationary engines.  The bibliographical services of APTIC, the Engineering
Index, and the Indices of the Transactions of the Society of Automotive
Engineers (SAE) and of the American Society of Mechanical Engineers (ASME)
were  studied,  and appropriate papers obtained.  As a result of this survey,
contacts were  initiated with staff members  at Southwest  Research  Institute
(SwRI), who  had conducted a  study for  the American Gas Association  (A6A)
on  natural gas fueled  engines used  in  pipeline  compressor  stations.   SwRI
has also  investigated  emissions  from  a variety  of engines  used in mobile
applications,  ranging  from  small gasoline  units to large diesel  locomotive
engines.   The  Bartlesville  Energy Research  Center of the Bureau  of  Mines,
U.S. Department  of  Interior, was found to  have  conducted a significant
 amount of R&D work  on  emissions  reductions from engines, mainly 100- to
 500-hp diesel  and gasoline units.  In addition to these studies, most
 published research was concerned with emissions from automobile engines.
        Business indices, such as Moody's and Dunn and Bradstreet, were
 consulted to  identify the domestic manufacturers of engines for  stationary
 applications.  However, the trade journals were  found to be much more  helpful
 for  this purpose.-7   These  included the Oil  and  Gas Journal.  Automotive
 Engineering,  and Power.   In addition, the  Diesel  and  Gas  Turbine Worldwide
 Catalog  was especially  useful^).  Other  sources were Federal Power  Commission
  (FPC)  publications, which  contained  information about engine-driven  electric
  generators, various  AGA documents,  which  gave  information on the gas pipeline

    manufacturers.
                                       A-2

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 industry's  use  of  engines,  and  statistical  surveys  by the U.S.  Department
 of Agriculture, which provided  some  data  on  agricultural  pumping  requirements.
 Some  annual  production  statistics  were  obtained  from the  Commerce Department's
 series of Current  Industrial Reports, but frequently these documents  did
 not divide  production figures into sufficient  subgroups to correlate  a
 production  trend with a particular application.   Therefore,  the majority
 of the production, marketing, and  application  data  were obtained  by direct
 telephone or written contacts with marketing representatives,  application
 engineers,  or environmental managers within  companies  who sell engines
 for stationary  application.
       Direct contacts with engine manufacturers  also  provided much of
 the data on emissions from uncontrolled engines,  control  technologies,
 and emissions from  controlled  engines.   In  addition,  a report by  McGowin(2)
 provided useful information about  large-bore engine  applications  and  utili-
 zation rates and one by Roessler,  et al.,(3) presented a  thorough  discussion
 of control  technologies used in mobile  applications.   Additional  information
 regarding stationary applications, control technologies,  and their costs
 were received from manufacturers in response to official  requests  for
 data by the Director, Emission  Standards and Engineering  Division, U.S.
 EPA.   These requests were sent  to manufacturers under  the  authority specified
 in Section 114 of the Clean Air Act.   Most of the data on  the effectiveness
of the various controls come from  laboratory experiments  at the manufacturer's
plants or, in a few cases, at special test centers such as at SwRI or
Bartlesville.
       An extensive telephone survey  was conducted during  July and August
1974  among local and state air pollution control  authorities (see Table A-l)
in an  attempt to locate potential examples of "best demonstrated control
                                    A-3

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       Table A-l.   AIR POLLUTION CONTROL AGENCIES CONTACTED IN
                   SEARCH OF CONTROLLED STATIONARY ENGINES
    State
Arizona
California
 Colorado

 Florida

 Illinois
 Missouri
 New Jersey
 New York

 Oklahoma

 Oregon

  Pennsylvania
  Texas
                 Office Contacted*
1.   Department of Health, Division of Air Pollution
    Control
1.   Bay Area       APCD
2.   Kern County    APCD
3.   Los Angeles    APCD
4.   San Bernardino  APCD
5.   San Diego      APCD
1.  Department of Health
2.  City and County of Denver  Health  Department
 3.  Tri-County Health  Department
 1.  Department of  Pollution Control:   A1r,  Noise,  and
    Solid  Waste
 2.  Dade  County
 1,   Illinois  EPA - Air Pollution (Chicago)
 1.   St. Louis      APCD
 1.   Department of Environmental Protection (Trenton
     Central Office)
 1.   Department of Environmental Conservation
 2.   New York City Department  of Air  Resources
 1.  Oklahoma City - County Health  Department
 2.  Tulsa City - County  Health  Department
 1.  Department  of  Environmental  Quality
 2.  Lane  County Air Pollution Authority
 3.  Mid-Willamette Valley Air Pollution Authority
 1.  Alleghany  County  Air Pollution Control
 1.  Air  Control  Board -Austin
 2.  Air  Control  Board - Houston
  aAPCD-Air Pollution Control District
                                   A-4

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 technology."  Based on this survey, which was planned to include all the
 geographical areas known to have relatively stringent regulations, it
 was concluded that no installed engines were currrently subjected to any
 emission limitations other than for visible emissions.  The only exception
 was the 140 Ib/hr rule for NOX from new engines in Southern California
 (see Section 2.2).  Since most uncontrolled engines under 4000 hp can
 meet this regulation, and since no larger engines are known to have been
 installed in that area recently, that rule did not lead us  to any examples
 of field-installed controlled engines.  Therefore, the evaluation of
 control  technology was to be based upon published emission  data and data
 obtained from engine manufacturers.
        Since no  installed engines  were found which could be cited as
 examples of units with "best" controls, no emission tests were conducted.
 However, a  San Jose,  California sewage plant (San Jose Water Pollution
 Control  Plant) was visited  to give a  better understanding of the operational
 flexibilities  available  to  users of large-bore  engines.(4)   This plant
 had  six  gas  engines  and  six  dual-fuel  units.
       The  direct contacts  were supplemented  by  visits to the  manufacturers
 listed in Table A-2.   The purpose  of  these visits  was  to obtain  more  information
 concerning  the status  of  their  R&D  efforts  in emission reductions,  their
 experience with the commonly  proposed  control technologies,  their estimates
 of the cost  and time  required to incorporate such  controls  on  their engines,
 and the  importance of  the stationary market place  in their  total  sales.
       The group meetings that  were held with representatives  of  engine
manufacturer's associations are listed  in Table A-3.   In general, the
meetings served to inform these representatives of the purpose of performance
standards for new sources, the process  of developing a standard,  including
                                        A-5

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informal and formal opportunities for input from all  interested parties,
and the reasons for considering that stationary engines should be regulated
by performance standards.   The meetings were also used to request information
of a general nature, such  as data on the effects of variable ambient condi-
tions (temperature, humidity, etc.)  on emissions, appropriate test cycles
(based on their knowledge  of engine usage patterns) possible engine operating
parameters that are known  to be directly and uniquely related to emission
levels and could be used in lieu of emission testing for compliance monitor-
ing.  As is also shown in  Table A-3, representatives of three industry
organizations met with EPA and commented on the draft SSEIS after it was
presented at the March 1976 NAPCTAC meeting in Washington, D.C.
       Several meetings were held between Acurex/Aerotherm and EPA  staff
during the development of the  draft document.   In  the first half of 1978,
two  public meetings were held  to discuss the proposed standard?, one before
the  NAPCTAC committee and the  other with the engine manufacturers.  These
are  listed  1n  Table A-4 along  with a  brief  description  of the  purpose, con-
clusion, and any redirections.
        In early 1978, Acurex was assigned  the  responsibility  for writing the
rationale chapter  of the SSEIS,  the  preamble to the  standard,  and  the  regula-
tion itself.   In addition,  Acurex was also assigned  responsibility for es-
tablishing  monitoring and emission  testing  procedures.   This  work  was  per-
formed with the advice  and  review  of EPA/OAQPS.
        Review of the original  draft Standards  Support Document and Environ-
mental  Impact Statement by  the Industrial  Studies  Branch,  Emission Standards
and Engineering  Division,  OAQPS was completed  on December 20, 1975, and
 the final  draft  was forwarded to the Industrial Studies Branch by Acurex/
Aerotherm on March 17,  1976.  The revised  draft SSEIS was reviewed by the
                                      A-8

-------
Standards Development Branch, Emission Standards and Engineering Division,
OAQPS by March 1978 and a final  SSEIS was forwarded to the Standards
Development Branch by Acurex/Aerotherm in July 1978.
                                 A-9

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                         REFERENCES FOR APPENDIX A


 (1)  Diesel and Gas Turbine Worldwide Catalog.   Diesel  and  Gas Turbine
 Progress.  Milwaukee, Wisconsin.   39.  1974.

 (2)  McGowin, C. G., Stationary Internal  Combustion  Engines in the United
 States.  EPA-R2-73-210.   April  1973.

 (3)  Roessler, W. V., A.  Muraszew,  and R.  D. Kopa.   Assessment of the Appli-
cability of Automotive Emission Control Technology to Stationary Engines
 EPA-650/2-74-051.  July  1974.

(4)  Offen, G. R. (Acurex/Aerotherm).   Trip Report.  San Jose Water Pollution
Control Plant.  (Interoffice Memorandum to F. E. Moreno, Acurex/Aerotherm)
June 5, 1975.                                                            '
                                      A-15

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                                APPENDIX B
Agency Guidelines for Preparing
Regulatory Action Environmental
Impact Statements (39 FR 37419)
 Location Within the  Standards
   Support and Environmental
 	Impact Statement	
 1.  Background and Description of
    Proposed Action

    Summary of Proposed Standards
    Statutory Basis for the Standard


    Facility Affected


    Process Affected


    Availability of Control
    Existing Regulations at State
    or Local Level
2.   Alternatives to the Proposed
    Action

    Environmental  Impacts
    Costs
 The  standards  are  summarized  in
 Chapter 1.

 The  statutory  basis  for  the standard
 is given  in  Chapter  2.

 A description  of the facility to  be
 affected  is  given  in Chapter  3.

 A description  of the process  to be
 affected  is  given  in Chapter  3.

 Information  on the availability of
 control technology is given in
 Chapter 4.

 A discussion of existing regulations
 on the  industry to be affected by
 the standard is included in Chapter 3,
 Section 2.3.
Environmental effects of delaying
the standards are discussed in
Chapter 7, Section 6.

The costs of alternative control
techniques are discussed in Chapter
8, Sections 2, 3, and 4.
                                    B-l

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Agency Guidelines for Preparing
Regulatory Action Environmental
Impact Statements (39 FR 37419)
Location Within The Standards
  Support and Environmental
	Impact Statement	.
3.  Environmental Impact of
    Proposed Action

    A1r Pollution
    Water Pollution
     Solid  Waste  Disposal
     Energy
     Other
The air pollution Impact of the
standards  1s considered 1n Chapter 7,
Section 1.

The water  pollution  Impact of  the
standards  1s discussed  1n Chapter 7,
Section 2.

The  solid  waste disposal  Impact  of
the  standards  1s discussed  1n
Chapter  7, Section  3.

The  energy Impact of the  standards
 1s considered  1n Chapter  7,
 Section  4.

 The environmental Impacts related
 to noise and thermal pollution
 are discussed 1n Chapter 7,
 Section 5.
                                       B-2

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                                   APPENDIX  C
                           EMISSION SOURCE TEST DATA
  C.I     DATA
         This appendix tabulates all the quantitative emission data that were
  obtained for large-bore engines during the  preparation of the Standard Support
  and Environmental Impact Statement.  These data include emission and fuel
  consumption rates for both baseline and controlled conditions.   Since no  controlled
  stationary reciprocating engines  are known  to exist in field installations,
  all the data were obtained from engine manufacturers,  who reported on the
 results of experiments  in their laboratories.   In  some cases, these  data have
 been made  public,  but  in most  instances they  were  received directly from the
 manufacturer as  a private communication.
        Large stationary  engines are expensive to purchase and operate,
 and controlling  their emissions has not previously received high priority.
 For these reasons, virtually no government,  commercial (other than manufacturers),
 or  university test labs have obtained one or reported on possible emission  reduction
 technologies that might apply to currently produced engines.l/  However,
 Southwest Research Institute  has  a two-cylinder  version of an Electromotive
Division (EN)) locomotive engine which  they  have  used for  emission  control

                                  c-i

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investigations(l). This  engine is no longer being produced by EMD, although
it represents most of  the current locomotive engine population.  According
to data supplied by  EMD, this model's  successor  has higher baseline NOX emissions
(14.7 g/hp-hr for the newer model  compared  to  9.1  g/hp-hr for the older two-
cylinder version at  rated conditions)  and lower  total  hydrocarbon emissions
(0.49 g/hp-hr compared to 0.92 g/hp-hr).   These  differences  are  consistent
with the increased efficiency of the engine.   New  EMD  data  (Engines  17,  18
and 19) showed the same trends with the application of controls  that  the SwRI
engine  data  did; consequently, SwRI's results are not  included here.
        The  data include engines which are currently marketed for stationary
 application  and also  several  units  used  in mobile and marine applications.
 However,  data from  installed  engines  were  excluded because these older units
 are not the same as those  new  units that would  have to meet any promulgated
 standards.
        NOX emissions were measured using one  of the four procedures  and
  several kinds of NOx analyzers.  These procedures and instruments  are
  identified  and  discussed in Section 4.2 for each  large-bore engine
  manufacturer that reported emissions data.  NOx emissions  were  measured by
  either a nondispersive  analyzer or a chemiluminescent instrument with a thermal
  reactor to  convert  the N02 to NO.   Results were reported as grams N02-
         Nondispersi ve infrared  analyzers (NDIR) were  used to measure the CO
  concentrations. Since the exhaust was  "dry,"  interference due to water was
  negligible.  When  C02 and oxygen  were measured,  an NDIR analyzer was used for
  the C02 and a  paramagnetic analyzer  for the  oxygen.   These  constituents  were
  generally sampled to check the other measurements  or to calculate total
  exhaust flowrate  if the inlet air flowrate into the  engine was  not  measured.
                                     C-2

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        Total hydrocarbon emissions  were measured in a heated  flame  ionization
 detector (FID).  The tubing and FID were maintained at  3750F  to  prevent
 condensation,  and hence,  removal  of any of  the  heavier  hydrocarbons.
 Therefore,  these measurements  were  made on  a "wet"  basis  because the water
 had not been removed.   The  results  were corrected for the water  content to
 make them correspond with the  NOx and  CO data.   Since the exhaust from gas
 engines does not contain these easily  condensible heavy hydrocarbons, the
 lines  and FID were  not  heated  in seme  tests on  gas  engines.   In  addition to
 these  total  hydrocarbon measurements,  a few manufacturers measured the
 nonmethane  emissions from gas  and dual-fuel engines.  Their methods and
 results are discussed in Appendix C.4.
        Four  engine manufacturers (Colt, Cooper, DeLaval, and White Superior),
 who  are members  of  the  Diesel  Engine Manufacturers Association (DEMA),
 measured  emissions  data according to the measurement procedure published  by
 DEMA(2).  Although the  DEMA methodology suggests that a three-mode cycle  be
 used for  engines that will be  used  at constant speed (essentially all
 stationary applications) and a six-mode cycle for units that will see
 variable speed  duty (marine  and locomotive), most of the results  reported
 here were collected prior to the final  publication of the  DEMA procedures.
 Hence,  emissions were usually measured only at rated load  and  speed.  However,
 some engines were also tested at selected part load  and speed  points.  These
 additional data  points appear on the following tables (see Tables C-l through
C-82) as derated operating points  or as variations  in the  engine  operating
speed.
       Several of the engines (Engine Nos.  30 through 33)  at the  low
 horsepower end of the large  engine category  were tested  according to the
                                  C-3

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California 13-mode cycle.  However, only the emissions  at rated conditions
were used here since the 13-mode automotive  cycle  does  not  represent
stationary engine usage, and no relationship was found  between  emission  rates
based on the average of the California 13-mode cycle and those  at  rated
conditions.
       The data were submitted in either tabular or graphical form.   In
the latter case the data points were clearly marked and could be converted
readily to the tabular format for Inclusion  in this appendix.   Other
operational data were either supplied by the manufacturer or obtained from
product Information literature.  Fuel consumption  values 1n all cases are
specific to the test that measured the emissions  and are not from  general
product specifications.
       Fuel consumption was generally reported 1n  terms of  Ib/hp-hr  for
dlesels and Btu/hp-hr for gas and dual-fuel  engines.  Conversion to  kcal/hp-
hr was accomplished using a lower heating value of 18,320 Btu/lb for dlesel
fuel and a units conversion of 0.252 kcal/Btu.  All data presented in this
document on emissions from diesel and dual-fuel engines are based  on operation
with No. 2 distillate (diesel oil).
       In several cases, a number of tests were performed on the same engine,
and consequently an uncontrolled value was reported for each control
technique.  In all cases the uncontrolled level precedes any controlled  data
reported for a particular test.  In the tabulations which follows, a separate
table 1s used for each engine, and the data are printed in numerical order
based on engine code number.  These data come from References  1 through  22.
These references are noted on the tables except where an engine manufacturer
has requested anonymity.
                                   C-4

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C.2    REVIEW OF AMBIENT CORRECTION FACTORS FOR APPLICATION TO LARGE-BORE
       ENGINE NOX DATA
       Ambient correction factors have been developed for automobile- and
truck-size gasoline spark ignition (SI) and compression ignition (CI)
engines(23).  The following sections will discuss the application of the
existing SI factors to natural gas engines (C.2.1) and the existing CI
factors to large-bore diesel and dual-fuel engines (C.2.2).  In addition, gas
turbine ambient correction factors will be examined for application to
large-bore engine emissions (C.2.3).  As these sections will illustrate, no
satisfactory ambient temperature correction factor has been developed for any
size of SI internal combustion engines, and only one study has considered
ambient temperature corrections for CI engines.  Therefore, Section C.2.4
will discuss an analytical approach to correct emissions for variations in
ambient temperature.

C.2.1  Ambient Correction Factors Developed for SI Engines
       A survey of the literature showed that correction factors for
gasoline-fueled engines have been developed only for ambient humidity
variations(24).  one of the studies also evaluated the effect of ambient
temperature and barometric pressure variations on exhaust emissions, but
found that engine-to-engine variations were too great to generalize a
correction factor for either temperature or pressure(25).  These studies
will be briefly discussed in the following paragraphs,  and then the ambient
humidity correction factors will be compared and evaluated for application to
the  large-bore natural gas-fueled engines in this study.
       The Automobile Manufacturer's Association contracted with the Ethyl
Corporation to conduct a  study on the  effect of ambient  air humidity,
temperature,  and pressure on  heavy-duty  (HD) gasoline engines^26). The
                                    C-£

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 results of this study for the effect of humidity later became the correction
 factor designated 1n the Federal Register for HD gasoline eng1nes(27).
        This correction factor was derived from emission measurements conducted
 on seven engines 1n accordance with the Gasoline-Fueled, Heavy-Duty Engine
 procedures 1n the 1970 Federal Register.  The test engines were Installed
 1n an engine dynamometer test cell where humidity,  temperature,  and pressure
 were varied.   The engines tested were gasoline-fueled, spark-ignited,  carbureted,
 heavy-duty truck engines ranging in size from 38 to 75 CID per cylinder.
 The compression ratios varied from 7 to 9.4,  and air-to-fuel  ratios varied
 from 14.4 to  15.7.   The objective of the study was  to develop factors  to adjust
 composite mass  emissions to  a standard  condition of 75 grains H20/lb dry air,
 90°F inlet air  temperature,  and  a barometric  pressure of 29.92 inches  of mercury.
        Figure C-l(28)  illustrates the effect  of humidity on  both A/F ratio
 and NOX emissions  (Federal nine-mode composite  cycle).  As this  figure
 illustrates,  a  reasonably good correlation  was  established between  changes in
 ambient  humidity and NOX emissions.   Note also  that A/F  ratios are
 essentially constant or  decrease  slightly with  increasing  inlet  air  humidity.
 The  composite cycle ambient  correction  factor was of  the form

                   K = 0.634  + 0.00654(H) - 0.0000222(H)2              (C-l)
 where      NOX corrected  = (K) NOX observed
                       H  = specific  humidity, grains  H20/lb dry  air
       Figures C-2(29)  and c-3(30) illustrate the effect of temperature  and pressure
 on A/F and NOX emissions for these same engines.  Obviously,   engine-to-engine
 variations were too.great to  generalize  a correction factor for either temperature
or barometric pressure.
                                   C-89

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        Both physical  reasoning and these results indicate that changes in
 ambient temperature and pressure affect the A/F ratio more than do changes in
 humidity.   Moreover,  it is well  known that the effect of A/F ratio variations
 on NOX emissions  depends on the  engine operating point on the NOX vs.  A/F
 curve (see Figure C-4)(31).   For example,  a decrease in A/F ratio for  an
 engine operating  at A in Figure  C-4 would  result in  a decrease in NOX
 emissions,  whereas a  decrease in A/F ratio for an  engine at C would cause an
 increase in NOX emissions.   The  author concluded,  therefore,  that engines
 operating  at different  A/F  ratios with different metering characteristics
 should exhibit  varying  (possibly contradictory)  effects on exhaust emissions
 for similar changes in  inlet air conditions.
        The  author also  indicated that  changes  in inlet air conditions  could
 affect fuel  distribution to  the  engine,  and this in  turn affects  NOX
 emissions.   This  effect is  illustrated in  Figure C-5(32).   In  addition,
 changes  in  inlet  air  conditions  which  change the engine A/F ratio also change
 the minimum  spark advance for  best  torque  (mbt).   Figure C-6(33)  illustrates
 how NOX  emissions  vary  with  A/F  for  the mbt  setting  and other  settings
 retarded from mbt.  Since some of the  engines  in that  study had no  vacuum
 advances, they  experienced,  in effect, retarded  mbt  settings  as their A/F
 ratio  changed.  Thus, their  emissions  would respond  differently to A/F  changes
 than  engines with  vacuum advances.   Therefore, the development of  a  general
 correction factor for ambient temperature  and  pressure  was  not possible,  although
 variations  in these parameters affected emissions  significantly.
       In two other studies, ambient humidity  corrections were developed  from
LD  gasoline vehicles(34>35).  In the first study, correction factor was
derived from emission tests  at 76°F  and at four  ambient humidities on a fleet
of  eight passenger cars operated on  a chassis  dynamometer set to simulate
                                   C-93

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derived from emission tests at 76°F and at four ambient humidities on a fleet
of eight passenger cars operated on a chassis dynamometer set to simulate
seven different road loads of the Federal seven-mode composite cycle for LD
vehicles.  These passenger cars were powered by gasoline-fueled, spark-
ignited, carbureted engines ranging in size from 42 to 59 CID per cylinder.
The compression ratios varied from 8.5 to 10.5, and air-to-fuel ratios from
14.6 to  16.4.
       Corrections for ambient  humidity were derived for both composite
cycle  and  constant  load.   The Federal Test  Cycle constant load  factor  is
considered more applicable to  large-bore  carbureted SI engines  which typically
operate  at a constant  load (nearly rated  load).  These factors  are
                   K =  0.7%  + 0.175(H/100)  + 0.129(H/100}2
                   composite  factor                                   (C-ZaJ
                   K =  0.844  + 0.15KH/100)  + 0.075(H/100)2
                   constant load, 50 mph                               (C-Zb)
 The results of this study were adopted by California to  correct emissions for
 anbient humidity for gasoline-powered vehicles under 6000 pounds <36).
         In the second study,  a  similar test program on gasoline vehicles was
 conducted to develop an ambient humidity correction factor that was adopted
 by EPA  to correct LD gasoline  vehciles(37>38) .  This factor is
                           K = 1/(1  - 0.0047(H  - 75))                   (C-3)
         In yet  another  study,  an  ambient  correction factor for  humidity was
  developed for  typical  research engines where A/F  and mbt settings  were held
  constant^39).   The  author  of  this  study  also noted the  effect  of A/F  ratio on
  NOX emissions  as  illustrated  in  Figure C-7(4°).   Based  on  this figure,
                                      C-96

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Krause(41)  reasoned that composite correction factors  would vary from
constant load factors since NOX emissions vs. humidity curves  changed with
A/F ratio.   Despite the validity of these observations, the correction factor
derived in this study is probably less applicable to large-bore engines than
those derived for gasoline vehicles, since in practice A/F ratios and spark
settings of large-bore engines are not necessarily held constant as they were
in this study  (e.g., spark timing is fixed as load changes for some engines,
and varies with load for other engines).
Comparison of  Existing Humidity Correction Factors for SI Engines
        Based on the  preceding  discussion, three  ambient humidity correction
factors are  potentially applicable to  large-bore, natural  gas fueled engines,
particularly four-stroke,  carbureted  versions.   These  factors are summarized
in Table C-83(42>43>44'45).   Figure C-8  is  a comparison of  the  three factors
over  a  typical  range of ambient humidities.   Note that only one of the factors
plotted is  a constant  load factor (Equation  (C-2b); the other three  are  based
on  composite test  cycles.
        As  Figure C-8 illustrates, there is  a considerable difference  in
 correction  depending on the study.  The results from  the  EPA/Scott  study show
 the greatest sensitivity to ambient humidity variation,  while the  results for
 HD gasoline engines show  the least.  This is not unexpected in  view of the
 previous discussion regarding the variation in engine responses to changes in
 inlet conditions depending on A/F ratio, fuel metering and distribution, and
 ignition (distribution operation) characteristics of  different engines.   The
 correction based on constant  load has been chosen as  the most suitable
 correction to be applied to  large-bore SI engines,  since these engines  are
                                     C-98

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  typically operated at constant load.   Thus,  this correction factor is most
  applicable to carbureted (4-NA)  natural  gas  engines.
         Application of any of the correction  factors  in  Figure  C-8  to  other
  engine types  (e.g.,  turbocharged units)  is questionable due to major
  differences  in inlet air intake  systems.  For>example,  data from the  draft
  SSEIS indicate that  NOX  reductions  due to water  induction  are  directly
  proportional  to water-to-fuel  (W/F) rates, up to W/F ratios  of 1.  Moreover,
  W/F  rates  due  to  ambient  humidity are a function of A/F ratio, as Figure
  C-9  illustrates.   Based  on this  figure, the W/F rate of a  carbureted natural
  gas  engine (trapped A/F « 17)  is about 30 percent lower for  a specific
  humidity of 100,  than the W/F  ratio of a turbocharged engine with a trapped
 A/F  ratio of 25  (trapped A/F ratios for turbocharged SI  engines typically
  range from 20 to  25)(«,47).   Note§  also> that the curves Qf constant  numidUy
 diverge with increasing A/F ratio.  Therefore,  it can be anticipated that NOV
                                                                             n
 emissions of engines  with different  A/F  ratios  will  respond differently to
 identical changes in  ambient  humidity.   Thus,  the application of  the constant
 load  humidity correction  factor (based on carbureted  gasoline engines)  to
 other than  carbureted,  large-bore SI engines  is questionable.
        Similar  conclusions can  also  be reasoned regarding the application of
 ambient  temperature and pressure  correction factors to NOX  emissions from
 engines  whose  air intake  as well  as  fuel  systems  differ  substantially.   As
 discussed earlier,  however, no  factors have been developed  for SI engines for
 either temperature or pressure.
 C.2.2  Ambient Correction Factors Developed for CI Engines
       A survey of  the literature established that two sources have reported
 ambient correction factors for truck-size diesel  engines(48,49). A study by
Krause, et al., was sponsored by the  Automobile Manufacturer's Association
                                    C-101

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  and  the  Engine Manufacturer's Association  and resulted  in correction factors
  for  both temperature  and humidity.  These  corrections were later adopted by
  the  EPA  for HD diesel engines(5°),  The other source reported corrections
  for  humidity only.
        In Krause's study, a correction factor was derived for six different
  engines run over a 13-mode cycle.  Emission procedures used were similar to
  "California Procedures for Diesel Engines  in 1973 and Subsequent Model  Year
  Vehicles Over 6001 Pounds Gross Vehicle Weight."  The heavy-duty truck
  engines tested were diesel-fueled, compression-ignition engines  ranging in
  size from 69 to 155 CID.  The compression ratios varied between  14.9 and
  18.7.  Inlet air conditions  were controlled to one of 19 combinations of
 humidity and temperature.  The  humidity conditions ranged from 35 to 125
 grains ^O/lb dry air, and the  temperature was  varied between  70°F  and  115°F.
 Barometric  pressure was  controlled to  28.00 ±0.2 inch  Hg at the  air cleaner
 inlet.
        The  engines  in  the study  were of the following types:
        •    Four-stroke turbocharged, direct injection (4-TC)
        •    Four-stroke turbocharged, prechamber  (4-TC, PC)
        •    Four-stroke naturally aspirated,  MAN  chamber  (4-NA, MAN)
        •   Four-stroke naturally aspirated,  (4-NA)
        •   Two-stroke  blower scavenged (2-BS)
        •   Four-stroke turbocharged, aftercooled (4-TC, AC)
       Unlike turbocharged large-bore engines, which are nearly always
aftercooled, only one of the  turbocharged engines in this study was
aftercooled.  That engine as  well as the 4-NA and the 2-BS units  were similar
in design to large-bore engines.   A correction factor was developed for  all
of the engines  as  well  as for individual  units.   The factor was of the form
                                    C-103

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                       K = 1/(A(H - 75)  + B(T - 85))

where NO corrected = (K)x (NO observed)  and A and B are related to A/F  ratio
(load).  The reference ambient conditions are 75 grains H20/lb dry air  and
85°F.  Figure C-lo(51) is a plot of the  coefficients A and B for each engine as
a function of load (or A/F ratio).
       Average values of A and B for all engines (as function of A/F) were
also determined.  This result does not appear wholly justified given the
variations 1n response to ambient humidity and temperature exhibited by the
different engine types depicted in Figure C-10.  Note that the 4-TC, AC unit
is  significantly less sensitive to ambient temperature variations over  the
load range than the other designs.  Therefore,  separate ambient correction
factors for  2-BS, 4-NA,  and 4-TC, AC units from this study were used on the
corresponding  large-bore designs  instead of  just one average  value of  all
engines.  The  coefficients A  and  B were  determined for rated  load  conditions
using  average  rated  load A/F  ratios that were  reported for  the  large-bore
engines.
        The  second  source(52)  which  examined  humidity effects  reported
 correction  factor  based  on experimental  tests  of a  2-BS  and a 4-NA engine.
        Ambient humidity corrections from both  of these sources  (assuming
 inlet  temperature is held constant, hence,  the B term  of  Krause's factor
 drops  out)  are illustrated in Figure  C-ll(53»54).   The SI (gasoline) factors
 discussed in Section C.2.1 are also plotted for comparison.  Note that there
 is little variation in correction factors for different diesel  engine  types
 with the exception of the 2-BS unit from the CRC report.   Moreover, the
 diesel-fueled (CI) engines appear less  sensitive to ambient humidity changes
                                     C-104

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 than SI  units,  particularly for  humidities  less than 75 grains H20/lb dry
 air.
        Initially, one might expect the diesel units to be more responsive to
 inlet humidity  variations, since these units operate at higher A/F ratios
 (approximately  25 to 40), and therefore, induct more ambient water than SI
 engines which operate more nearly at stoichimetric ratios (*15 to 17,
 depending on the fuel).   Diesel engines, however,  have a greater thermal
 inertia than SI engines  due to their higher trapped A/F ratios (as well  as  a
 different combustion process).   Apparently the higher  thermal  inertia in the
 diesel  units more than offsets  their higher effective  water induction rate;
 thus,  their NOX emissions are  less  sensitive to  changes in ambient humidity
 than SI  engines.  This explanation  is  corroborated  by experiments  which  have
 demonstrated that water  injection,  as  a control  technique,  produces
 significantly greater NOX reductions in SI  units than  it does  in CI  (diesel)
 units  (see  Section 4.4.7  of the  draft SSEIS).
       The  Krause study  also investigated the  effect of ambient temperature
 on NOX emissions.  Figure  C-12(55) presents  the correction factors that  were
 derived for  engine types  similar to those in the present study (humidity is
 assumed constant, hence,  the A term of  Krause1s factor  drops out).   The
 reference temperature is taken as 85<>F.  This figure shows that the naturally
 aspirated and blower-scavenged engines NOX emissions are more sensitive to
 inlet air temperature changes  than the aftercooled  design.   Since Krause's
 study systematically examined  the effect of both inlet  temperature  and
humidity for a number of  CI engine types,  his factors were  selected for
application  to similar large-bore engine types.
                                   C-107

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  C'2'3  Potential  Application of Gas  Turbine Ambient  Correction Factors  to
         reciprocating ic Engines            ~	~—	——
         Since  no  ambient  correction  factors  have  been  developed  specifically
  for  large-bore engines,  all existing  correction  factors for  internal
  combustion  engines were  examined  including  those for  gas turbines.  There  is
  a  considerable amount of technical  literature on gas turbine ambient
  correction factors as a result of the promulgation of emission standards for
  aircraft engines and the proposed emission  standards for stationary gas
 turb1nes(56-6l)t   Th1s Sect1on describes these various factors and their
 potential application to the large-bore engine data 1n the present study.
        Gas turbine combustion characteristics have  some common features with
 those in diesel  engines.   Both the gas turbine primary combustion zone and
 the diesel  combustion chamber  can  be characterized  as  a well-stirred reactor,
 and both use similar  distillate fuels  or natural  gas.   On  the other  hand, the
 gas turbine  combustion  is a steady-state,  constant  pressure process,  whereas
 the diesel  is  an  unsteady,  variable  pressure combustion  process.
 Nevertheless,  the similarities  of  the  two  systems warrant  an  investigation  of
 existing  gas turbines correction factors.
       Many  investigators have  developed ambient  humidity correction factors
 based on  a model that relates NOX formation  parameters of temperature,
pressure, equivalence ratio and residence time (using the kinetic rate
equations for NOX formation)(62).   Humidity enters this model  through its
effect on reaction (flame) temperature.  Most researchers have shown that the
effect of humidity on NOX  formation takes the form

       NOX corrected/NOx observed  = exp (K  (Hobserved  - Hreference))
                                   C-109

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where      Href = specific humidity at  reference  (standard)  conditions
              K = empirical constant that ranges  from 14 to  30,  generally
                  taken as 19(63)
       Figure C-13(64'65)  is a plot of this correction factor and shows that
 it  agrees reasonably well  with the HD diesel (4-TC, AC) factor discussed in
 Section C.2.2  (the  gas turbine factor was adjusted to a reference humidity of
 75  grains HaO/lb  dry air  to correspond with the reference humidity of the HD
 factor).
       Other  sources have shown similar  agreement  of  humidity effects on NOX
 emissions  of  diesel  engines  and gas  turbines as  illustrated  in Figure
 C-14(66).   The gas  turbine humidity correction factor was derived from
 empirical  data based on water injection  as  a means of NOX control in  gas
 turbines.   The ambient humidity was converted  into an effective  water-to-fuel
 ratio by multiplying the ambient  humidity loading  by the near stoichiometric
 A/F ratio existing at  combustion.  Then the empirically derived water
 injection correction factor of Ambrose(67) was used to calculate the
 percentage reduction in  NOX.  It is reasoned that the overall A/F ratio is
 inappropriate  since much of the water vapor in the inlet air never reaches
 the  primary  combustion  zone  because it  is  vented  for engine cooling or enters
 downstream as  dilution  or wall cooling  air.  Based on this result, one can
 conclude  that  changes  in humidity  appear to affect NOX formation in gas turbines
  in much the  same way  as  diesel (1C)  engines.  However,  it  should be remembered
  that a number of adequate humidity correction factors  have  been developed
  for 1C  engines;  therefore,  this  gas turbine result is  of limited value, but
  serves to reinforce the more global application of these corrections.
                                      C-110

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         Gas turbine temperature corrections were also examined for application
  to reciprocating engine data.  Figure C-15(68,69)  1s a comparison of the HD
  diesel (4-TC, AC) correction factor with various gas turbine factors.
  Obviously,  there 1s little agreement with the exception of one factor.
  Presumably these differences arise from differences  in inlet air compressor
  and  combustor design.   The gas  turbine  factors,  however,  have some
  flexibility in that  they are related to the  combustor  inlet  parameters  of
  pressure  and  temperature.  Therefore, an  attempt was made  to relate  changes
  1n NOX formation  of  reciprocating  engines  to  changes in  ambient  temperature
  by estimating  the cylinder temperature  before  combustion in  a typical
  reciprocating  engine and using the compressor  pressure ratio  and the
  assumption of  1sentrop1c compression to calculate temperature.  This
  calculated temperature was then used with the  gas turbine factors.  Figure
  C-16(70,71) presents the results of this approach for several different forms
 of gas turbine factors.   Again,  these results do not  correlate well  with the
 HD diesel  factor, probably due to the empirical nature  of the gas turbine
 equations  and the large  differences in air intake systems between engines and
 turbines.
        On  the  basis  of this brief  review,  gas  turbine ambient correction
 factors do  not make  a useful  contribution  as  potential  ambient  correction
 factors for  reciprocating engines.

 C>2>4   L."i*"f.]j!*1cal Approach for th«» Ambient Temperature Correction of  NO,
        emissions                                                          "
       Since no temperature correction factor has been reported In the
 literature (see Section C.2.1) for SI engines,  and no systematic emissions
data exist (either SI or  CI) from which to base a temperature correction for
large-bore engines In general, an attempt was made to  develop a
                                    C-113

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semi analytical  approach for relating changes  1n  ambient  temperature to  changes
1n NOX level from large-bore engines.  This  approach  was used  to  estimate  how
changes In ambient temperature affect NOX levels.
       The analytical approach 1s based on the fact that ambient  temperature
changes affect NOX emissions by their direct effect on both fuel/air (F/A)
ratio  and peak flame temperature.  As the ambient temperature rises,  the
 inlet  air becomes  less  dense.  Since the air Intake volume 1s essentially
 constant, the  engine will  Inject  a  smaller mass of air; that  1s,  the F/A
 ratio will  Increase.   This change 1n F/A ratio  Is  related to  a change  1n NOX
 level  for  both SI  and  CI  engines.
        The  temperature of the  air in a diesel engine or fuel/air mixture  in
 a dual-fuel or natural-gas engine after compression  is  correspondingly
 changed by a change in ambient (inlet) air temperature.  That is,  an  increase
 in inlet air temperture results in  an even greater charge temperature  after
 compression.  This increase in charge temperature leads to a higher  peak
 flame  temperature and, consequently, greater NOX levels.  The increase in NOX
  !evel  due  to  an inlet  air temperature  increase is related to specific engine
  design parameters such as F/A ratio,  degree of aftercooling, and compression
  ratio, as  well  as  the fundamental  nature of the combustion process (i.e.,  CI
  or SI).  Therefore, the  relationship  between NOX  level  and inlet air
  temperature is anticipated to be highly dependent on the  particular engine
  design.
         The discussion above indicates that NOX level is primarily  a function
  of both F/A ratio and inlet air temperature.   That  is,
                                  NOX = g(f,T)
                                       C-116

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   where      f = F/A, fuel/air ratio
              T = Ta,  ambient inlet  temperature
              N = NOX,  oxides of  nitrogen
              The subscript R denotes  a reference ambient condition

         Since  we are  interested in predicting changes in NOX level rather than
  absolute NOX  level we may mathematically represent a change in NOX to a
  change in ambient temperature as

                         dN = (aN/3f)T df + (8N/aT)f di
  or
                                                                        (C-4)
                          dN/dT =  aN/af df/dT + aN/gT

  where  the derivatives on the  right side of Equation (C-4) remain to be
  evaluated.   The first partial derivative, 3N/3f, represents the change in NOX
  emissions due  to  a change in F/A at constant aibient temperature,  while the
  second partial, 3N/3T, represents the change in NOX due to temperature
  variations at constant F/A.   This mathematical  formulation can  be  portrayed
 graphically as shown in Figure C-17.   The  diagram  shows  NOX  vs.  fuel-to-air
 ratio,  the downswing curves,  and  load  vs.  fuel-to-air  ratio,  the  upsloping
 curves, for  a typical  turbocharged  diesel  engine.   The basic problem is to
 find  the change in NOX at constant  load due to some ambient temperature
 change.  For  example,  assume the ambient temperature, T, is greater than the
 reference temperature, TR.  Starting at the uncorrected fuel-to-air ratio,
 one locates Point A on the NOX production curve and Point B on  the  load
 curve.  Then moving over, at  constant  load, to  tne  rererence  temperature load
curve, one  locates Point  C and,  hence,  the  reference fuel-to-air ratio.  Now,
                                    C-117

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  knowing the reference fuel-to-air ratio, one can move from Point D to Point
  E on the reference temperature curve.  Thus, the change in NOX production
  resulting in this change of ambient  temperature is indicated as  ANO¥.
                                                                     A *
         The change in NOX level  with  F/A for  a  constant  ambient temperature,
  3N/3f,  is presumed known for  a given engine  or  engine type.   This
  relationship can  be  established frcm data that  can be obtained in the
  laboratory on  a sample engine.  In addition, it  is assumed that the NOX vs.
  F/A  plots  of Figure  C-12  have  similar slopes for different ambient
  temperatures.  Therefore, only NOX vs. F/A data at one ambient temperature
  are  required to evaluate the derivative.
        The derivative df/dT, expresses the rate of change of F/A  ratio with
 a change in ambient temperature.  Wu  and McAulay have derived the following
 expression relating F/A  to ambient temperature  (at  constant  load)  for  both
 turbocharged  and naturally aspirated  engines*7*).

                                f - 'R  (T/TR)B
 and
                                                                      (C-5)
                    B • (1 + n) -  (1 - 61) n  (k - 1/nK)

where        k  * Cp/Cv, ratio of specific  heats
            n  • turbocharger  adiabatic compressor efficiency
            n  =  turbocharger  exponent  frcm equation  TAn rc  =  constant where
                0.5  <  n <  1 depending  on  turbocharger  compressor pressure
                ratio
           rc  -  turbocharger  compressor pressure ratio
           ei  •  (Tc  - Tm)/(Tc - Ta)
                                   C-119

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where Tc, Tm are compressor exit and intake manifold inlet temperature,
respectively.  Then, differentiating Equation (C-5) with respect to inlet
temperature we can evaluate the term df/dT in Equation (C-4).
           df/dT - B(fR/TR) (I/!'  - B(fR/TR) (1 +

                   *  B(fR/TR)  (1 +  (B - 1)  (AT/TR))                    (C-6)

 Since B is  always  less  than  2  and TR  is 7QOF  =  530°R,  a  nominal  change in
 ambient temperature  of  25°F  makes
                             (B -  1) T/TR  < 1/20

 Since this term is small compared to unity, we can approximate the derivative
 by
                               df/dt a B (fR/TR)
 Thus,  the term from  Equation  (C-4) that  predicts the  change in  NOX due to a
  change in F/A is  evaluated  as

                       3N/af  df/dt  = (9N/9f) (B)  (fR/TR)                 (C-7)

         An expression is now required to  relate the change in NOX level to a
  change in ambient inlet air temperature,  i.e., the partial derivative 3N/3T
  of  Equation  (C-4).  This dependence can be evaluated by first relating
  changes in ambient  temperature to changes in flame temperature using the
  following relationship from  Williams' Combustion Theory(73) suggested by
  Wilson, Muir,  and Pellicciotti^74).
                                       C-120

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            Tfl  • TB + 1/Cp  ((Q -  L)  YM/1  + Cp(Te8 -  TB))/(1  + Yox/1)    (C-8)
   where      Tfl  = droplet diffusion  flame  temperature (75)
              T« s 1sentrop1c  compression temperature
              CR s compression ratio of engine
              TM s manifold air temperature, related to TA by degree of
                   turbocharglng and aftercoollng
              TB = boiling point temperature of the fuel
               Q = heat of combustion per  unit mass of fuel
               L = latent  heat  of  vaporization of  the  fuel
             YOX = ambient  oxygen mass  fraction
               1  =  stoichiometric oxygen-to-fuel ratio  (by mass)
             Cp  =  specific heat of  the fuel/air mixture

 Then, the change in flame temperature is related to a change in NOV
                                                                   /\
 production using the Arrhenius relation

                   dNOx/dt « exp(-K/RTf1)  ;  K/R = 123,000°R

 If it is assumed that  the  rate of NOX  production  is independent  of  time,  one
 can readily  integrate  the Arrhenius equation  to yield  the following expression
 for the  ratio of NOX produced  at a  given  ambient  temperature, T, and a
 corresponding flame temperature, Tfl, to that at the reference condition.
                       = exp (K(Tfl - TflR)/R(Tfl x Tf]R))            (c.9)

The partial derivative can then be approximated in finite difference fom by

                        3N/9T,N(1-NR/N)/(T-TR)                  (c
                                   C-121

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Now by substituting Equations  (C-7),  (C-9),  and  (C-10)  into Equation  (C-4) we
obtain:
                  dN . Bf R 3N  .
                                N
1 - exp
'lC]l
 R  Tfl xTf1R Jl
                                  (C-ll)
                                           T-TR
        A preliminary  evaluation of this expression for a turbocharged diesel
 engine predicts  a 1-percent  change in NOX per W change in ambient inlet air
 temperature.   For a constant intercooler effectiveness and turbocharger
 compressor efficiency,  a 1-degree  change in  ambient  temperature corresponds
 to a 1-degree change in manifold  inlet  temperature.   Therefore, this
 analytical expression can be checked using  NOX  emissions  data vs.  manifold
 air temperature  (at  constant load) for  a turbocharged,  diesel engine.
         Emissions  data for the manifold air cooling control  (see Figure 4-34 of
 the draft  SSEIS)  indicates that this technique  produces  a 0.1- to 0.3-percent
 change in  NOX per degree Fahrenheit for diesel  engines.   Emissions data
 reported by  Ingersoll-Rand  (and from Figure 4-34 of the draft), show about a
  1-percent  change in  NOX per  1°F change in manifold  air temperature for
  turbocharged SI engines^).   Since NOX emissions from SI engines are more
  responsive to changes  in manifold air  temperature,  it appears  that this
  analytical approach overestimates the  effect of  inlet air temperature on NOX
  emissions from this turbocharged CI engine.  The assumption  of a constant  NOX
  production rate  with peak flame temperature may be more  valid for SI  engines
  than  CI engines  owing to differences in the combustion  processes.
                                      C-122

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        The approach outlined here has the potential to incorporate many
 different parameters into a single correction factor.  Additional  terns could
 be added for any other operating parameters  that  have a significant effect  on
 NOX emissions,  either directly or by their effect  on F/A or Tfl.   Once  the
 appropriate  relations are established,  it may be  possible to predict  changes
 in NOX  levels  as  a  result  of  changes  in  any one of  these  variables  caused by
 ambient  variations.
       These goals  are somewhat  ambitious; therefore, the most logical first
 step is  to gather available data taken at different ambient conditions and
apply the method to prove its validity.  At this time, however,  there is
insufficient  information for either SI or CI  engines to substantiate this
approach.
                                  C-123

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C.3    REVIEW OF NOX MEASUREMENT METHODS
       Previous studies have indicated that sampling instrumentation and
procedures significantly affect emission levels.  Furthermore, no one
standard procedure has been adopted by all of the manufacturers of  stationary
1C engines reporting  emissions.  That  is,  eight  large-bore  engine
manufacturers  who  reported  emission data used either  chemiluminescent  (CL)  or
nondispersive  infrared  (NDIR)  and  ultraviolet  (NDUV)  instruments  and one of
four  emission  measurement  procedures  (SAE, EPA,  EMD,  or DEMA).-
 Therefore, this section will  present  a detailed discussion of the instrument
 and sample acquisition practices used by the engine manufacturers.  The
 purpose of this discussion is to identify possible variations in exhaust
 emission levels attributable to particular measurement equipment and/or
 procedures.   Specifically, this section will:
         ,    Establish which instruments, sampling trains,  and  procedures  were
             used by  each manufacturer  who  reported  NOX emissions
         •    Summarize the  potential  sources  of  uncertainty relating to each
             measurement practice
         •   Evaluate the variability among manufactuers' emissions data due to
  the following discussion will begin by illustrating typical measurement
  uncertainties in present sampling practices.  This analysis will show that
  significant  uncertainties in measurements can arise  due to differences  in both
  instrument and sampling procedures.  Therefore, both  of these sources of  error
  will  be  discussed  as  they apply  to the instruments  and  procedures  used  by the

   2/Alc0j  cott, Cooper,  DeLaval, Electro Motive,  Ingersoll-Rand, Waukesha,
     and White  Superior.
                                        C-124

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  eight  large-bore engine manufacturers.  Then these practices  will  be  compared
  and the uncertainty in each manufacturer's NOX measurements estimated.
  c'3-1  Previous Studies of Exhaust Measurement Variation
         Before evaluating each manufacturer's sampling practice, it is of
  interest to examine the present "state-of-the-art" of internal combustion
  engine exhaust measurements of NOX.   Three recent studies have been conducted
  to compare the measurements of NOX made by different  laboratories from the
  same  emission source.   In  two of these studies,  NOX measurements were made,
  simultaneously,  in  the  same laboratory using  identical  procedures.   In the
  other  study,  the  same emission source  was  sent to each  laboratory.   These
  studies  illustrate  the  magnitude of emission  variations  attributable  to
  instruments and sampling procedures.   They also  indicate  the reproducibility
 of emissions measurements,  both  within  a laboratory and among  different
 laboratories.  The  results of  these studies will  serve as a basis for
 comparing potential data variations due to the measurement practices of the
 eight  large-bore engine manufacturers considered  in the current study.
        A series of cooperative emissions tests was conducted by the
 Coordinating Research Council  (CRC) to evaluate  measurement methods used to
 analyze diesel exhaust  emisions from truck-size  engines.   In Phase III of
 this program,  six  laboratories sent sampling  teams to  one  location to make
 simultaneous measurements (using  NDIR  analyzers)  of a  multicylinder
 engine(77).  The engine  used in this study was a  six-cylinder,  300-cubic-
 inch, four-stroke, direct-injection diesel.  The  procedures  that  were  used
 during this test program to measure NO,  CO, and C02 evolved  into  SAE
Recommended Practice J-177<78).   In Phase IV of that program> ^
was circulated to 15 laboratories to:   (1) verify  that the generally good
                                    C-125

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agreement of Phase III emission levels were the result of improved sampling
procedures, and (2) obtain NO/NOX data using CL analyzers^).
       Table C-84(80>81) shows the results of these two cooperative tests.
Although the Phase III variations appear reasonable, the Phase  IV  results
indicate poor  agreement among  the laboratories.  These  larger uncertainties
were  attributed to poor calibration procedures  (span  gases  out  of  spec,
instruments  not calibrated)  and  possibly  some  variation in  engine
performance.   In  addition,  it  was  noted  that the  average NO concentration
measured at rated load by the  CL analyzers was approximately 23 percent lower
 than that measured by NDIR.
        A more recent cooperative test program conducted by the CRC evaluated
 EPA's revised heavy-duty diesel engine NO/NOX measurement methods and
 instrumentation^).  Six participants made a  series of NO/NOX measurements
 on a multicylinder engine,  simultaneously,  and produced the range of
 uncertainty shown below.  A range is  shown  because the results were  analyzed
 in  three  different groupings:   (1) all  data,  (2)  those which remained  after
 eliminating  questionable results  from participants who encounter  sampling
 problems, and finally,  (3)  those  which  were left  after excluding  both
 questionable data and results obtained  from instruments with long sample transfer
  times.

               13-mode       Standard Deviation      Standard Deviation
               (q/hp-hr)           (q/hp-hr)         	(Mean,_%)	
      NO     8.03  - 8.21         0.42  - 0.29              5.9 - 3.5
      NOX    8.05  - 8.16         0.30  - 0.17              3.8   2.1
   All but  one  of  the  participants  used a CL analyzer,  and  the results from the
   one NDIR analyzer  (a new reduced interference design with a NOX  converter)
                                       C-126

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were equivalent to those from the CL analyzers.  Thus, based on simultaneous
tests using the same instruments, sampling practices, and emissions sources,
uncertainties in emission measurements among laboratories ranged from 3 to 6
percent for NO, and 2 to 4 percent for NOX.  In addition, the repeatability
within a  laboratory ranged from  2 to 7 percent for NO and 1 to  3 percent  for
NOX.
       In contrast  to the  above  program,  the eight  large-bore engine
manufacturers  used  one  of  four  test  procedures  (SAE,  EPA, DEMA, or EMD)  and
 either CL or  NDIR/NDUV  instruments.   Furthermore,  the NDIR's  were  not reduced
 interference  designs.   Hence, their  data are  likely to vary more due to
 measurement practices  than the truck engine results.  The following
 discussion will first examine the sources of such variations  from differences
 in both   instruments and sampling practices.  Then an attempt will be made to
 suggest  uncertainty bounds for  the emisions data from each manufacturer.

 C.3.2  Variations  in NOv  Emissio^ Related to the NOv Instrument
        Since the development of commercial chemiluminescent analyzers,
  (1971),  various  studies have been conducted to compare  their operation  with
  the  already  established NDIR analyzer.   All of these studies have shown the
  NDIR analyzer  to record consistently  higher  levels  of  NO than  the CL analyzer
  for  a given  source(83-85).   Three  of  the large-bore engine manufacturers
  reported NOX emissions using NDIR's and the other five used  CL analyzers.
         Table C-85 shows the NOX instruments used by each of  the
  manufacturers.  Scott Research Laboratories made the emission measurements
  for Ingersoll-Rand and White-Alco, since neither manufacturer presently owns
  emission measurement  equipment.  Note that an electrochemical  instrument was
  used by Shell Oil Research  in  1971 to measure NOX from one Cooper-Bessemer
                                       C-128

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and one Ingersoll-Rand engine.  None of the manufacturers has used this
instrument since then; therefore, no attempt will be made to correlate those
emissions with instrument differences.  Only Waukesha and GMC/EMD continue  to
measure NOX emissions with NDIR analyzers, and Waukesha has recently  acquired
a CL analyzer.  Thus, all but one manufacturer will be using CL  instruments
in the future.  In the following paragraphs, the principle of operation  of
the NDIR and CL instruments and associated sources  of error will be briefly
reviewed.  Then the  results of NDIR/CL  comparisons  will be summarized to seek
a method of expressing emissions on  an  "equivalent  instrument"  basis.

C.3.2.1  NDIR  Instrumentation
       The NDIR  instrument  was  introduced nearly 20 years ago  and  has
continued  to be used widely as  a CO  and 0)3  detector.   In addition,  it was
used  extensively  to  detect  NO,  HC,  and  S02,  but  other  methods  are  not
supplanting  it for these species.   Its  principle of operation  depends upon
 absorption  of  infrared  radiation by the gaseous  sample.   Figure C-18
 illustrates  a  typical NDIR  instrument.   Built-in optical  and gaseous filters
 are used to  produce a narrow infrared beam band  width  to compensate  for
 interference (absorption) by other constituents.
        Despite these precautions,  water vapor and C02, to some extent,  may
 cause positive interferences (high readings) even though refrigerant  and
 chemical driers are used to  remove water vapor.   Desiccants, however, have
 been found to cause significant interferences as well as water  vapor (see
 later discussion  and Section C.3.3).   In addition  to these problems,  the
 response of the NDIR instrument to the specie of interest is nonlinear  in
 some  instrument designs, necessitating a carefully constructed  calibration
 curve using at least four,  and preferably six to eight,  calibration  gases.
                                      C-130

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C.3.2.2  Chemllumlnescent Analyzers
       Chemiluminescent analyzers, 1n contrast to NDIR instruments,  have been
developed only recently (1971) for source sampling.  Nevertheless,  the  CL
instrument has gained increasing application for the measurement  of NOX
(NO + N02) and NO.   In this type of  instrument ozone, 03,  is  reacted with
nitric oxide, NO,  to produce  a chemically excited  state  of N02*.  which  emits
light as  it  decays to stable  N02.  The  intensity of  this emitted  light  is
proportional  to  the NO  concentration present  in the  sample.  The  analyzer
uses  a  photomultiplier  to detect  the light.
        Figure C-19 is  a schematic  of a  CL  analyzer and  illustrates the
 reaction  of  ozone with  NO in  the  reaction  chamber  of the  instrument.  The
 Instrument is easier to calibrate than  some NDIR's due to  its linear response
 to NO,  and thus requires fewer calibration gases.   Note that a N02 * NO
 converter is depicted 1n Figure C-19.  There are basically two types on the
 market.  One device consists of a stainless steel tube which is  heated to
 «1200°F and essentially  converts all N02 in the sample  to NO.  The other
 device catalytically converts N02 to NO.   In this way just NO or both  NO  and
 N02 can be measured, depending on whether the sample gas  is  fed  directly  to
 the reaction chamber or  passed through  the converter first.  The N02 level  is
 then deduced by subtracting  the  NO  level from the total  NO*  reading.
        Potential  problems  encountered  in  this  instrument include quenching of
 the  excited N02 by other species,  converter  inefficiencies,  and  interferences
 caused by chemiluminescence  of  other gases.   In  general, quenching (by C02 or
 H20)  is  negligible in  CL instruments;  particularly if water is  removed from
  the sample before analysis and  low pressure (vacuum) reaction chambers are
  used to  reduce quenching by C02.  Nevertheless,  some quenching  problems have
  been observed  during measurement of fuel-rich automotive exhausts.  Quenching
                                       C-132

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effects, however, have not been observed during measurements on truck-size
diesels, whose exhausts are similar to those of large bore stationary engines
(i.e., *15 percent oxygen).
       Converter problems are avoided by thermal conditioning of new
converters and by making regular checks of converter efficiency (>90
percent).  Interferences are minimized by the  instrument manufacturer through
the choice of spectral filters and photodetectors.

C.3.2.3  Sources of  Instrument Error
        Sources of error for each of the  instruments  listed  in Table C-85 are
summarized in Table  C-ee^86"94).   Note that  neither  the quenching  effect nor the
converter problems of the  CL  analyzer  should occur when measuring  large-bore
engine  exhausts  with a properly operated  and maintained CL  analyzer.   Present
NDIR  analyzers,  on the other  hand, are  susceptible to  errors due  to
 interference despite sample  conditioning  to  remove water.   This Interference,
combined with  the  relative ease  of operation and accuracy of CL analyzers, has
 led to  an increasing preference  of CL's  for  NOX measurements.   As an example,
 EPA's proposed revisions  to the  Heavy Duty Diesel and  Gasoline Engine
 Sampling Procedure specify CL analyzers.   The following section summarizes
 comparisons  of CL and NDIR/NDUV measurements of NOX.  These comparisons will
 be the basis for expressing NDIR/NDUV measurements as equivalent CL levels.

 C.3.2.4  Correlations of CL to NDIR/NDUV
        As discussed  above, NDIR analyzers are subject to water vapor
 interference despite  sample conditioning to  remove water vapor.   These
 interferences cause  the instrument to indicate higher NOX  levels  than are
 actually present.   A comprehensive study conducted  by TRW  (with Scott
                                      C-134

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C.3.3  Variations 1n NOv Levels Related to Sampling Procedures
       In addition to the choice of instrumentation, differences in sampling
procedures can cause variations in reported emission levels.  This was
clearly illustrated in Table C-84 for the Phase IV cooperative tests where  15
laboratories made measurements of an identical source.  Since four basic
sampling procedures (DEMA, SAE, EMD, EPA) were used by the eight large-bore
engine manufactuers, some variation between their reported emission  levels
can probably be  attributed to differences in their sampling  practices.  The
sources of these  uncertainties will be  identified and  the four sampling
procedures compared and  evaluated  in this section.

C.3.3.1    Sources  of  Sampling  Error
       The two major problems  encountered  in measuring engine exhausts are:
 (1)  chemical  changes that  occur  during  transfer  of  the sample to the
 analyzer,  and  (2) error due  to improper operation  of  the analyzer.   Figure
 C-20 is  a simple schematic of  an engine sampling system.  In transferring the
 exhaust  gas  sample to  the analyzer,  care must be taken to ensure that all of
 the NOX  (NO  + N02)  or  NO (when only an NDIR is used)  originating from the
 engine exhaust reaches the analyzer.   For these reasons sample lines are
 heated to prevent condensation or kinetic conversion of constituents.  High
 sample flowrates (short sample residence times) are maintained to minimize
 sample degradation during its transfer from the engine to the analyzer,  and
 water removal devices are employed to minimize instrument interferences  from
 water vapor.  Similarly, it is  important that the analyzer  be calibrated and
 all components,  such  as N02 + NO  converters (on CL instruments), be
 functioning properly.   Therefore, adequate analyzer  specifications  and
 calibration procedures  are  essential for accurate emission  measurements.
                                      C-138

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       Table C-88(a)(101-107) presents a more detailed  summary of  sources  of
sample transfer error.  As this table Indicates, heated sampling  lines
coupled with low sample residence times are essential to preserve  the  Initial
amounts of NO and N02 contained in the sample gas.  Furthermore,  leak  checks
of the entire sampling system (particularly on the vacuum side) should  always
be performed to assure that the sample gas reaches the  analyzer undiluted.
Water removal 1s required with NDIR analyzers; therefore, care must be  taken
to minimize the time available for NO to be converted to N02 which can  then
be absorbed by the condensed water from the sample gas.  Chemical  driers
(deslccants) are an unacceptable water removal device since they promote the
N02 •»• NO reaction and absorb N02 (see Section C.3.2).
       Table C-88(b)(108) summarizes Important analyzer related procedures
required for accurate measurements.  Care must also be  exercised  in operating
emission measurement instruments.  Frequent calibrations should be performed
using accurate, certified blends of calibration gases.  Zero and  span  checks
also serve to Indicate potential instrument problems as well as necessary
gain adjustments.  Span gases should be frequently cross-checked with
calibration gases or checked against a NBS standard since even certified
gases can be in error.
       Some calibration curves for NDIR analyzers are nonlinear; therefore,
several calibration gases (minimum of six) should be used to calibrate  the
instrument(109).  These instruments also experience some hysterysis after
sitting unused; therefore, frequent calibration is necessary.  Also,
calibration points should be curve-fit using a higher order polynomial.  In
addition, efficiencies of NOX converters (on CL analyzers) should  be checked
regularly.  Finally, strip chart recordings of data are superior to visual
                                    C-140

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           TABLE  C-88(a).  SOURCES OF SAMPLING ERROR:   THE SAMPLE TRANSFER
                               Sampling System
        Source
          Error
                                   Correction
 •   Unheated
    sampling  line
•  Long sample
   residence times
0  Sample line
   connections and
   fittings
•  Water removal

   —  Refrigerant
      Chemical
      drier  (desiccant)
 NO •*• NOg; N02 adsorbed
 during water removal:
 Observed 40-percent
 loss of NO when sample
 residence times were
 35-40 sec (101)
Heated Line;
                  ad-
 sorbed during water re-
 moval : 6-7% NOy loss
 for system response
 times3 greater than
 25 sec (102)
 Cold Line:  12-percent
 NOX loss  for sample
 residence time of
 13 sec (103)
 Leaks  that  dilute  sample
 gas: Observed 25-percent
 loss of NOX due to pre-
 fliter leak (104)
N02 adsorbed in condenser;
(105)
N02 ->• NO and drier "eats"
NOg.  Negative or positive
errors with cold lines
(SAE procedure) depending
on how drier conditioned
(106,  107)
                              Heat line to 375°F
Use short sample line
and/or flowrates to
limit system response
to 15 sec or less.
                              Leak check system be-
                              fore testing
                              CL:  Locate condenser
                              after converter.
                              NDIR: Maintain high
                              sample flow through
                              condenser, remove
                              H20  as it forms.

                              Do not use chemical
                              driers
System response time « sample residence time + Instrument response time
                                     C-141

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        TABLE  C-88(b).  SOURCES OF SAMPLING ERROR:  INSTRUMENT RELATED
         Source
•  Instrument drift,
   ozone shortage (CL),
   plugged capillary
•  Converter
   malfunction (CL)
 t   Visual  rather  than
    stripchart  readings
 t  Calibration and
    span gases
                               Instrumentation
                                    Error
Low NO  readings
      A
Not all N02 converted to
NO, results in low NOX
reading also possible for
NO to  exceed NOX levels
 Analyzer meter  only  ac-
 curate  to  ±3  percent.
 Visual  averaging  less
 consistent than chart
 averaging  (108)
 Change of constituents
 with time, or erroneous
 certification
                                   Correction
Calibrate instrument
frequently.  Zero and
span before and after
each measurement for
all instrument ranges.
Instrument should meet
minimum performance
criteria.
Perform converter
checks regularly.  Use
known standard to check
converter efficiency.
 Use  stripchart,  aver-
 age  levels  over  an
 interval  for which
 steady state condi-
 tions exist.
 Use certified gases of
 specified blends.
 Cross-check span and
 calibration gases.
                                      C-142

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  analyzer meter readings since a permanent record is  produced,  and emission
  levels  can  be  averaged  over  a time interval  more accurately and consistently.
  C.3.3.2  Sampling  Procedures:   EPA,  DEMA,  SAE,  EMD
         Having  completed this  brief review of sources  of  sampling  error,  we
  can  examine  each of  the four  measurement  practices presently used by  the
  eight large-bore engine manufacturers.  Table C-89 is a  comparison of  the
  EPA, DEMA, SAE, and  EMD emission measurement practices^10-113).   The
  information for the  EPA procedures is based  on the revised  EPA Heavy Duty
  Diesel Emissions Regulations as proposed  in  the Federal Register, Volume 41,
 No. 101, May 24, 1976.  This revised procedure requires CL  analyzers for
 NO/NOX measurement, establishes instrument and calibration  specifications,
 and defines  sample  transfer configurations and practices.
        This  comprehensive EPA regulation was  recently verified  through
 cooperative  testing by both manufacturers  of  mobile diesel engines and the
 EPA-Ann  Arbor Mobile  Sources  LaboratoryUH).  The six participants in this
 program  (see  Section  C.3.1) made essentially  equivalent  NOX  measurements
 for  a series  of eight tests.   Two participants,  however,  did experience a
 small, but consistent, NO/NOX  crossover  (NO levels greater than  NOX levels).
 Nevertheless, the standard  deviation  of  measured  NOX  levels  was  generally
 small, ranging  from 2  to 4 percent  (of the  mean  level).   Therefore, the EPA
practice will be the  basis of comparison for  the  other measurement  practices.
       The potential  sources of measurement uncertainty of the other three
procedures (DEMA, SAE, and EMD) are summarized in Table C-90.  The sampling
trains for these three procedures, as well  as  the EPA  setup,  are illustrated
in Figure C-21.   The DEMA procedure  specifies  a CL analyzer and  the SAE/EMD
                                    C-143

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             TABLE C-89.  COMPARISON OF SAMPLING PRACTICES
Test Procedure

DEMA:  No time between modes specified
EPA:   5 minutes
SAE:   20 minutes
EMD:   30 minutes

DEMA:  Data recorded and averaged over 10 minutes
EPA:   Data recorded over last 2 minutes
SAE:   Data recorded over last 5 minutes
EMD:   Data recorded over last 3 minutes


Instrument Calibration - DEMA and EPA are CL; SAE 1s NDIR; EMD 1s NDIR/NDUV

DEMA:  Analyzers calibrated semimonthly.  No details of calibration given.
EPA-   Check  NOX converter once per week (must be at least 90-percent
       efficient);  leak check system, calibrate  analyzer, check sample
       line residence time, and quench  check every 30 days
SAE:   Calibrate monthly
EMD:   Checked  and  calibrated monthly,  semiannually and annually

DEMA:  Number of calibration gases not  specified
EPA-   Span analyzer with  calibration gases  having nominal concentrations
       of 30, 60,  and 90 percent  of full scale concentrations
SAE:    Use calibration  gases that are 25,  50, 75, and 100 percent  of
        instrument  range used.
 EMD:    Use 4  calibration  gases

 DEMA-   No specifications  for  calibration or  span gas  blends  and  dilutents
 EPA-    Blends and  dilutents specified and  accurate within 2  percent of
        true concentration  or  traceable  within  1  percent of NBS blends.
        Span gas traceable  to  within  1 percent  of calibration gas.
 SAE:   ±2 percent  accuracy on  gas analysis certification
 EMD:   ±2 percent accuracy blends and dilutents  defined by  EMD

 DEMA:   No analyzer specifications required
 EPA:   Specifications for response-time, precision,  noise,  zero  ana
        span drift, and linearity             ,.,*,,.       u  ++-
 SAE:   Accuracy should be ±2 percent full-scale deflection or better
 EMD:   Same as SAE
                                C-144

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                          TABLE C-89.  Concluded

                 ~— •—+****— m

  Sample Transfer
                  lt-!1 (S'S.'} probe* configuration  not  specified
                  number and s1ze of n°les  In S.S. probe
           l' Probe» no configuration specified
        s.S. probe, configuration specified

 DEMA:  Sampling Une material  not specified
          a n ess stee1' teflon.  or P^ven  Inert

                        °r tefion
 EPA? !
 SAE:   Unheated
 END:   Unheated

 DEMA:   No sample Une length specified

           '                                 1nstrurent response
 SAE:   No length specified
 EMD:   No length specified


 DEMA:  Chemical driers can be used
 EPA:   Not allowed

 SAE:   Refrigerant and chemical  drier specified
 EMD:   Same as SAE
                                       ,
SAE:   Condenser and drier before  analyzer
EMD:   Same  as  SAE  for  NDIR.  NDUV does not use wfr rernoval.
                                   C-145

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procedures require an NDIR Instrument.  The EMD practice also utilizes an
NDUV analyzer, 1n series after the NDIR, to measure N02 In the sample.
       Table C-90 clearly Indicates that there are several sources  of
measurement uncertainty possible for the DEMA procedure, largely  as a  result
of  its failure to define  instrument and sample transfer practices.   Its  most
obvious  shortcoming  is the potential  degradation  of the NO  and  N02  in  the
sample gas  as  it  passes  from the  probe through  an unheated  sample line (of
unspecified length)  and  condenser before  entering the CL  analyzer.   High
 residence times  would also  promote NOX loss for  this  configuration.  One
 large-bore engine manufacturer demonstrated that the  sample residence time
 must be less than 3 seconds to prevent significant loss of N02 in  the sample
 (12-percent loss for a 13-second residence time) as  it passed through a cold
 sample  line and condenser (see Table  C-88).
         Similarly, SAE and EMD practices can also  lead to a  loss  of NOX  as  the
 sample  passes through an unheated  sample  line,  a condenser,  and  a  desiccant
 before  reaching  the analyzer.  As  discussed previously, the desiccant
 converts N02  to  NO  and  absorbs N02.
         Comparisons  of  the  SAE sampling train  with the proposed EPA train
  indicated that  SAE measured concentrations of NO are understated by 15 to 40
  percent during  the first few measurement modes of the federal 13-mode
  composite cycle, then are equal  in the seventh or eighth modes, and finally
  are overstated by  about 10 percent in the last modesd").  These results and
  the study conducted by TRW suggest that  the desiccant requires  a  period  of
  time to equilibrate.   If a new  drier were used  before each  13-mode test
  (permissible under present EPA  regulations), NO  levels would  tend to be low
  (since levels would be understated  until the drier  had equilibrated, possibly
  not until  the  last, rated  speed,  low power modes were being measured).  If
                                       C-148

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   the drier was not replaced, or if it was preconditioned, the NO levels would
   tend to be overstated.  This is probably the case for those large-bore engine
   manufacturers who use driers,  since their engines are typically operated
   about an hour before they are  stabilized and measurements are begun.
          The EMD procedure is similar  to  the  SAE procedure with the  exception
   that  both  NO  and  N02 are measured  using NDIR and  NDUV analyzers.   Results
   from  the TRW  study(H6),  based  on  automotive exhausts>  .^.^ ^
   NDIR/NDUV  NOX measurements  were about 20 percent  higher  than CL readings  (no
   water removal for CL sample).  Apparently, the positive  biases (interference
   and drier)  more than offset potential NOX loss due to the cold sampling in
  that study,  m addition to the positive NDIR biases, NDUV analyzers have a
  history of  stability problems,  usually manifested  as a drifting (high)
  reading.  One  study  attributed  this error to  interference due to  carbon
  particle  buildup^!?).

  C.3.3.3   Summary and  Conclusion  of  DEMA,  SAE,  and  EMD Practices
        In sugary, it appears that  the DEMA practices  will generally  lead  to
  negative errors due to NOX loss  in  transporting the sample from the engine to
 the analyzer.  At this time the absolute uncertainty associated with this
 practice is  unknown relative to  the EPA procedure.   Limited results  (see
 Table C-87)  suggest this error could be as much as  -10 to -15 percent
 depending  on the  amount  of N02 in the  sample  (estimated to be 2 to 10 percent
 of the  total  NOX) and  the  extent  that  NO  is converted  to  N02  during  the
 sample  transfer.
       The positive bias of the SAE  procedure  gives a  12-percent error in the
NO reading.  The EMD procedure, which measures both NO  and N02 causes a  20-
percent error in the NOX reading.   Nevertheless, both procedures could
                                    C-149

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experience as much as a -40-percent error in the NO or NOX reading if the
chemical drier has not stabilized.  Thus, the uncertainties in NOX
measurements for the SAE and EMD practices appear to be significantly greater
than the DEMA practice.
        Finally, the  EPA procedure defined for the heavy-duty diesel  and
gasoline engines appears to have minimized the  various sources of measurement
error  and  should  give  more accurate  and  consistent  NOX readings.  Therefore,
each of the manufacturer's sampling  practices will  be evaluated  in  the  follow-
 ing section by  comparing  it  to the EPA procedure.
 C.3.3.4  Comparison of Manufacturer's Measurement Uncertainty
        Table C-91 summarizes each manufacturer's practice in terms of
 procedures that could lead to measurement error.  Note that three of the four
 DEMA manufacturers  using cold sample  lines have located their water traps
 near  the  analyzer  instead of  at the  engine as  is recommended  In the DEMA
 practice.   Therefore, this setup will promote  additional  loss of NOX in the
 exhaust  sample.   In addition,  Colt  and  Waukesha have relatively  high sample
  residence times  which will  also  promote NOX  loss.
         The potential  errors  in measurement resulting from these practices are
  estimated in Table C-92U18-122) relative to the EPA procedure.   (Blanks
  appear in Table C-92 for items which do not apply to a particular
  manufacturer.)  These uncertainties are depicted for each manufacturer in
  Figure C-22.  Errors due to system  leaks are  not  included in the figure  since
  this  error cannot  be generalized.   Also, the  uncertainty bands were
  constructed assuming that errors of the  same  sign were  additive.   Note that
                                      C-150

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these uncertainties substantially exceed the 4-percent scatter in NOX  levels
observed during verification tests of the EPA procedure.
       NDIR and NDIR/NDUV instrument biases have been included in this figure
and are based on the TRW study(123K  Note that the potential negative 40-
percent error of Table C-92 is not  included in Figure C-22  since the
manufacturers generally operate the  engine long enough to condition the  drier
before measurements are taken.  The  data for Waukesha  indicates  that  sampling
errors can be as  large as  instrument bias, but  in  the  case  of Cooper  and
GMC/EMD,  instrument biases  predominate.

Conclusions
        The  above  analyses  of  instruments  and  measurement practices  suggest
the following  conclusions  about  the reported  data:
        •   The  exhaust data which were reported using the DEMA,  SAE,  or EMD
            practices  should be banded by the appropriate uncertainty level.
            In general, measurement  uncertainties  are expected to range  from
            -15 to +5 percent for DEMA data and -20 to +20  percent for the
            SAE/EMD data.
        •   Waukesha's data contains the greatest  uncertainty since:   (1)  only
            NO was measured,  (2)  other significant sampling problems  could
            have been present, and  (3) the amount  of  N02 in the  exhaust  was
            unknown; thus  correction of NO to NO + N02 would be  speculative.
         •   The  Ingersoll-Rand and  White-Alco exhaust  emissions  data  appear to
            have  the  least  measurement uncertainty (±5 percent)  since their
             sampling  procedure was  essentially  identical to the  EPA procedure.
                                      C-154

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        The  previous analyses also  lead one to conclude that the EPA heavy-
 duty engine method should be preferred over any other method previously used
 for sampling stationary reciprocating engines.  Therefore, any test method
 developed for these engines should follow the same basic sampling procedures
 and utilize the same basic sampling system.   In the mean time,  the DEMA and
 SAE/EMD sampling practices should include more carefully specified sampling
procedures,   and the use of NDIR/NDUU instruments  should be carefully  re-
viewed  because  of their bias relative to  CL  instruments.
                                  C-155

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C 4    THE EFFECT OF NOX CONTROL TECHNIQUES ON NONMETHANE HYDROCARBON
       EMISSIONS
       It is well known that the application of NOX controls to 1C engines
can cause the emissions of other criteria pollutants to  increase.  Therefore,
CO and HC emissions may require control as well as NOX  levels.  However,
attempts  to  regulate HC emissions from  large-bore  engines  are  not
straightforward  since  most  data for  these  engines  are  in terms of  total
hydrocarbon  (THC),  rather  than reactive HC which  is  the criteria pollutant.
        Moreover, the  Office of General  Council (OGC)  has indicated that EPA
 should establish, if  feasible, standards  for the criteria pollutant, NMHC, to
 avoid legal challenges of a THC standard  under Section 111 of the Clean Air
 Act(124).  The OGC added, however, that EPA could set  standards on THC if
 such  an  approach:  (1) simplifies sampling procedures,  and  (2) allows the  use
 of existing data.  If EPA follows this approach, they  must  show that  a
 standard for THC would cost manufacturers  and users no more than  an  standard
 for  NMHC.   The  purpose of  this memo  is to  investigate  this  issue.
         Data from Section  4.4  indicated that,  in  general,  the  application of
  N0x controls to large-bore 1C engines  resulted in increases of 5  to 50 percent
  in  THC levels (see Figure 4-52).   However, the THC levels reported for the
  gas and dual-fuel engines contained both methane, (CH4> *  noncriteria
  pollutant, and  NMHC, the regulated HC pollutant.  (NMHC emissions are defined
  here as all other hydrocarbons in the exhaust sample.)   If NMHC  levels  change
  differently than THC levels  with the  application of NOX  controls,  separate
  control regulations  may be required for  NMHC levels.   Therefore,  the data for
  THC and NMHC  (where  measured) from gas  and  dual-fuel  engines are reexamined
           , *    •   K   MOV control  techniques affect  NMHC levels  relative to
   here to determine how  NOx uu
   THC levels.
                                     C-156

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         In the following sections, uncontrolled levels of THC and NMHC will be
  compared  for both new (laboratory)  and installed (field engines).  Then these
  emissions will  be evaluated after the application of NOX control techniques
  that  were reported in Section 4.4.   In addition,  the measurement techniques
  for both  NMHC and THC will  be briefly reviewed.   Based on this  evaluation, a
  recommendation  will be  presented  concerning  the  separate control of NMHC
  emissions.

  C'4>1  Comparison  of  Controlled THC  and NMHC  Emissions from  Gas  and Dual-
        t-uei  Engines                "~	—	
        Previous investigators  have shown that NMHC  levels  are generally  less
  than 20 percent of the THC emissions from natural gas  engines.   Figure C-23
  illustrates this conclusion using data reported by  Southwest Research
  Institute (SwRI), and two engine manufacturers, Colt and Cooper.  The SwRI
 data were from engines installed on gas transmission pipelines(125), whereas
 the manufacturer's data were from new engines that were measured  in
 laboratories.  All the THC data were measured with flame ionization detectors
 (FID's).   Nonmethane emissions were determined as the difference  in THC and
 methane  levels.   Cooper and  Southwest measured methane emissions with a gas
 chromatograph.  Colt physically removed all  nonmethane portions  of the sample
 and then measured  the  methane  remaining with  an  FID.
       Figure C-23 shows  that  THC  levels for  pipeline engines ranged from 1
 to 9 g/hp-hr  and were  lower  for four-cycle designs (1 to 3 g/hp-hr)  compared
 to two-cycle  levels  (3 to 9  g/hp-hr).   THC emissions from the engines tested
 by the two manufacturers were  generally  lower  than those  from the pipeline
 engines for both two-  and four-cycle  designs.
       Although the THC levels  for the new gas engines  were lower than those
for the installed engines, the  NMHC levels were greater.  As  a consequence,
                                  C-157

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   a greater fraction  of the THC emission from the new engines were NMHC as
   compared  to  the  pipeline  units.   On  the average,  NMHC emissions  were only 6
   percent of THC  levels  for the installed engines,  but 23 percent  for the new
   engines.   These  differences may be related  to  the condition of the  installed
   engines which were  tested  as  found.  That is,  older,  installed gas  engines
  may have  had more blowby of unburned fuel and  have been operating off peak
  combustion (i.e., requiring maintenance or  an  overhaul), thereby causing
  greater emissions of unburned fuel (methane).  Furthermore,  lower peak
  temperatures  associated with  less than optimum combustion may have resulted
  in fewer emissions of partially oxidized fuel (i.e., reactive hydrocarbons or
  NMHC).
         Figure C-24 shows  uncontrolled THC and NMHC levels for Colt  and Cooper
  dual fuel  engines.   (No measurements  of installed  dual-fuel  engines  were
  available.)   These data are similar to  the limited data for  manufacturer's
  gas engines,  indicating that NMHC  levels  from these  engines  range from 10 to
  20 percent  of THC  levels.
         In  the following sections,  the levels  of NMHC  and the ratios  of
 NMHC/THC for these gas and  dual-fuel engines  will  be  evaluated after  the
 application of NOX controls.  These comparisons will  show whether NMHC
 levels  respond differently to controls than to THC levels, and, therefore,
 whether  any standards would have to be written in terms of NMHC.
 Ct4'2  The  Effect  of  NQK Control Techniques on THC  and NMHC Levels
       Figures C-25 through  C-30 illustrate how  the application of NOX
 control  techniques affect THC and NMHC levels from  gas and  dual-fuel  engines.
 Note that data were reported for both pipeline engines and  those tested in
manufacturers'  laboratories.  In general, these  figures  show  that derate
                                  C-159

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 and air-to-fuel ratio changes cause THC emissions to  increase, but  retard
 (R), external EGR, and manifold air temperature  (MAT) reductions do  not
 change the uncontrolled THC.  Furthermore, for all of these techniques,  NMHC
 levels remained about the same percentage of THC as they were in the
 uncontrolled engines.  That is, NMHC emissions from both gas and dual-fuel
 engines change in the same proportion as do THC  levels, or remain in the same
 proportion (where THC remained unchanged) with the application of NOX
 controls.
        Figure C-25 shows that, in general, derating caused THC to increase
 less than  50 percent, although extreme amounts of derate (>25 percent) caused
 uncontrolled THC levels  to increase from 1 to 3 g/hp-hr to 2 to 5 g/hp-hr.
 In one  case,  THC emissions increased from 5 to 18 g/hp-hr for an installed
 pipeline engine  that, possibly,  required maintenance.   In all  cases, NMHC
 levels  ranged from 5  to  25 percent of  THC levels  and did not change  with
 derating.   The increases  in  THC  levels are probably related to the lower
 exhaust and peak  temperatures  of part  load operation.
        Similarly,  Figure  C-26  shows that increases  in  A/F cause  moderate
 (10- to 25-percent) increases  in  THC levels.   One 2-TC installed  gas engine
 was  the exception;  THC levels  increased  75 percent  from  11  to  19  g/hp-hr, and
 may be related to  a worn  condition  of  the  engine  requiring  maintenance  (i.e.,
 excessive blowby).  Increases  in A/F of  gas engines  that  are already
 operating lean tend to lower peak combustion  temperatures and prevent complete
 combustion.   Consequently, HC emissions  increase, although  not as rapidly as
with decreases in A/F from rich (less than stoichiometric)  operation  (see
Figure 4-29).  Note that the ratio of NMHC to THC remains essentially
constant with increases in A/F.
                                  C-167

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       Figures C-27 through C-29 indicate that retard, EGR, and MAT do not
cause THC or NMHC levels to increase.  The application of retard delays the
combustion of the air/fuel mixture, resulting in higher exhaust temperatures
which, combined with an excess of oxygen, effectively oxidizes most
remaining unburned fuel.  The application of this technique, however, causes
fuel consumption to increase  (see Figure 4-27).
       In contrast to retard, EGR and MAT controls usually  cause  no  increase
in fuel  consumption.  It follows that if complete combustion  is maintained
(evidenced  by unchanged fuel  consumption) HC  emissions  should  remain low  or
unchanged.   With the  application of  EGR, unburned HC are  recirculated or
trapped  and then combusted during  the next  cylinder  firing.  The  limited  data
for  EGR, illustrated  in Figure  C-28, show that  NMHC  and THC levels remain
unchanged.
        With the reduction of manifold air  temperature,  however,  HC emissions
 can be expected to increase as the reaction of this  specie proceeds at a
 lower temperature.  Data shown in Figure 4-52 indicate that THC  levels
 increase, but  less than 25 percent, with manifold temperature reductions.
 Nevertheless,  the limited data for both NMHC and THC levels shown in Figure
 C-29  indicate  that these emissions  remain unchanged.
         Figure  C-30 shows how the application of combinations  of  controls
 affects NMHC and  THC emissions.  The results of this figure  are  mixed.   It
 should  be  noted that this  data  is  limited,  representing  six  engines from two
 manufacturers. For  three of the  six engines  shown, combined  controls  cause
 THC and NMHC emission  to  increase  in the same  proportion.   However, data for
 two 2-TC designs  (one  dual  fuel,  the other gas)  indicated that  NMHC emissions
 decreased  (when THC  levels increased)  with the applications of:   (1) retard
                                    C-168

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 and air-to-fuel for the dual fuel unit, and (2) EGR and derate for the gas
 engine.
        Opposing this result and of more concern, one 4-TC design showed that
 NMHC emissions increased from 0 to 0.2 g/hp-hr when THC emissions decreased
 from 5 to 3 g/hp-hr with the application of retard and MAT.   Nevertheless,
 the NMHC level is  small, representing only 5 percent of the  THC level.  It
 should also be noted that,  despite precautions to avoid sample degradation,
 the manufacturer of this engine experienced some inconsistencies in
 determining NMHC  levels  (i.e.,  measured methane levels exceeded THC levels).
 Therefore,  the following section will briefly  consider the procedures for
 measuring  both NMHC and  THC  before a recommendation concerning the  separate
 control  of  NMHC emissions  is  presented  in  Section  C.4.4.

 c-4.3   Measurement  Practices  for NMHC and  THC  Emissions
        The  development of a  separate  standard  for  NMHC emissions  is  largely
 dependent on the demonstration  of  techniques for  detecting NMHC directly,  or
 those which detect  NMHC  emissions  indirectly by measuring  methane and  THC.
 The NMHC level  is then determined  by  the difference of  the two  measured
 levels.  It should be noted that the  accuracy of indirect  techniques depends
on the accurate determination of both methane and THC  levels.
       At the present time, there  are basically three methods  available for
determining NMHC emissions.  These are(126):
       •   Gas  Chromatographs (GC):  Provide direct measurement of methane by
           separation from other hydrocarbons.   NMHC measurement is  obtained
           indirectly by  subtraction of methane from THC or directly by
           measurement of remaining nonmethane  hydrocarbons.   When NMHC is
           measured  directly,  the methane value is also obtained and can be
                                  C-169

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           subtracted from a THC measurement  (with  FID)  as  a  check  of  the
           NMHC measurement.
       t    Nondispersive  Infrared  (NDIR):   Also  provides direct  measurement
           of methane.  NMHC measurement  is obtained  indirectly  by  subtrac-
           tion  of  methane measurement  from independent  THC measurement.
       •    Selective  Combustor  (SC):   Gives a direct  measurement of methane
           by  selective combustion of all  nonmethane  hydrocarbon, allowing
           measurement  of the  remaining methane  on  a  conventional THC
           analyzer such  as  a  flame ionization detector  (FID).  NMHC
           measurement  is obtained indirectly by subtraction of methane from
           THC.
All of these NMHC techniques use a conventional  heated flame ionization
detector (FID) to make one measurement of either NMHC using  a GC, or THC
using a GC, NDIR, or SC.
       Gas chromatographs are commercially available  and were used  by
Cooper(127) and  SwRI to  report NMHC  levels from their engines.   This method,
however, cannot  perform  real-time  analysis (continuous  rather than  bag or
batch  sampling), a capability desired  by  development  engineers  and  present in
other  major emission instruments  (e.g.,  NOX,  CO, SOX  analyzers).  In
addition,  this  instrument requires specialized  training to operate and
maintain.
        Selective combustors have  only recently  become available commercially.
They are  simple and  inexpensive compared to  a GC but apparently require  more
 development.   This is  because  not all lighter paraffins (e.g.,  ethane and
 propane)  are  eliminated from  the  test sample during  the selective removal of
 all NMHC  emissions.   This results in higher methane  (or smaller NMHC) levels
 than were actually present.  Colt used this method to report NMHC  levels  from
                                   C-170

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  their  engines.   However,  no  comparisons  with  GC  data  were  available  to
  determine  if this effect  may have caused  the  Colt  NMHC  data  to  be
  understated.
        The third NMHC instrument, the NDIR, exists  as a prototype  and  also
  requires more development before becoming available commercially.
  Nevertheless, the instrument  has demonstrated accuracy and freedom from
  interference for either batch or continuous sampling of methane emissions.  It
  is also believed that it will require greater maintenance than existing
 NDIR's since it is more complex.
        It should be noted that Fisher and Goodwin(128) supported the
 development of standards for NMHC's.  They noted, however,  that although
 measurements  of NMHC levels  were feasible, significant time and expense would
 be required to  adequately develop the necessary instruments and procedures.
        Cooperative  studies of the SAE measurement method have also
 indicated that  futher development of heated  FID's is required to reduce
 measurement uncertainties(129).   The most recent  study consisted of a
 comparison  of data  from  one  diesel engine emission  source measured  during
 round-robin tests.   The  results  of this study  showed that THC levels  varied  by
 10  percent  (on  the  average) for  a given manufacturer and 22 percent  among
manufacturers.   It was concluded  that further  development of  this measurement
method was necessary  to  reduce this  scatter.
       The preceding discussion  indicates  that measurement methods for  NMHC
have not been adequately demonstrated at this  time.  In addition, studies  of
FID instruments indicate that considerable measurement uncertainty can  arise
from these instruments even though an accepted practice is followed.
                                  C-171

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C.4.4  Recommendations for the Control of NMHC
       Based on the preceding results, it 1s recommended that any control of
NMHC levels be based on the measurement of THC  levels.  This can be  supported
by recognizing that:   (1) in general, NMHC levels  change in the  same manner
as THC levels with the application  of NOX control  techniques; and  (2)
monitoring NMHC  levels accurately  is considerably  more  difficult than for THC
since gas chromatographs  or physical conditioning  of the sample  is  required.
Therefore,  if  standards for hydrocarbons  are  deemed necessary,  they should be
based on  the  reduction of THC,  rather  than NMHC,  levels.
                                    C-172

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  C.5     DEVELOPMENT  OF  CONVERSION  BSNOtf  TO NOV  (ppm)  CORRECTED TO 15
         PERCENT  02                     xx



         All  emissions data  in  Alpendix C.I had  been  reported in terms of


  brake  specific  emissions,  BSNOX  (g/hp-hr).   In addition,  applying


  percent emissions reduction to the  sales  weighted uncontrolled emissions


  levels  (section 4.3.4) results in emission  limits having  the


  brake-specific N0x format.  Since a concentration format  (ppm)  has  been


  selected for the standard, a method must  be derived  to convert  the  BSNO
                                                                         A

  limits to concentration limits.


 C-5-1  Converting BSNOX to N0;c Concentration Format


        By definition, the volumetric concentration of NO  in the exhaust
                                                         A

 is simply the volume of NOX divided by the total exhaust volume.  If the


 mass  concentration  is known,  dividing each (the mass of NO  and exhaust)
                                                           A

 by the respective molecular weights will give the volumetric


 concentration.   This may  be equally done on a brake-specific basis.


 Therefore,  since the molecular weight  of NOX will be defined equal  to


 N02  (  46),  the  volumetric  concentration  of NO  can  be written  as
                                              A
                                          BSNOX
         NOX (ppm)        = - HE

            concentration   Brake specific exhaust gas, g/hp-hr
                             molecular weight of exhaust  gas
       Both brake-specific N0x  limits and the molecular weight  of  NO
                                                                    A

are known.  However, the brake  specific exhaust gas flow  and the modecular


weight of the exhaust gas are in general not available.   Furthermore, to


set emission limits for each fuel type, the average ratio of exhaust flow


to exhaust gas molecular weight must be determined.  This may be done by
                                C-173

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assuming properties of the fuel and a reference 15 percent 02
concentration in the exhaust gas.  The following procedure has been usedto
determine the ratio of exhaust gas flow to exhaust gas modecular weight,
using data obtain from available brake-specific fuel consumption.
       For any hydrocarbon fuel, the chemical reaction may be written  as:
 CxH  + Z 02 + 3.76Z N2 * x CO,, + y/2 H.,0 +  (Z  -  x  - y/4)  02  + 3.76 N2   (2)
 This  is  a generalized  equation,  ignoring the small  concentrations of other
 constituents  such as  NO   HC,  CO etc.,  which are less than 1.0 percent.
                        A
 The moles of  exhaust  gas produced per mole of fuel  burned is therefore
 [x+ y/2  + (Z  - x - y/4) + 3.76 Z]; and for dry products water is removed
 leaving   [x +  (Z - x - y/4) + 3.76 z] moles of dry exhaust.  This reduces
 to [4.76 Z -  y/4] total moles of exhaust gas.  The molecular weight of the
 gas is therefore the ratio of each constituent multiplied by the
 respective constituent molecular weight:
  M
                       x       44 + (Z - x - y/4) 32 +
   'exhaust gas   [4.76Z _ y/4]      [4.76Z - y/4]      [4.76Z - y/4]
                                       or
        M
         exhaust gas   [4>?6Z . y/4]
(44x + 32Z - 32x - 8y + 105.28Z)      (3a)
                                    C-174

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       The exhaust mass flow must be determined next.  Since the total
mass flow remains constant, the mass of exhaust gases per mole of fuel
burned is:
              m dry  exhaust  « m fuel  + m  air  - m water  formed
                                                                      (8)
 From equation (1)  above,  (Z)  moles of air are burned with each mole of
 fuel, and (y/2)  moles of  water are formed,   By multiplying by the
 molecular weight of each, the mass flows are as follows:
                 1 x (12x + Y) + Z[32 + 3.76(28)] -(y/2)(18)             (9)
  Substituting  equation  (5)  again  (assuming  15  percent  oxygen  in  exhaust);
   m
m drv exhaust _ {12x +y) + (3.5x + 0.743y)(32 + 3.76(28)) - (y/2)(18) (10)
  mole fuel
                          m dry exhaust _ ^x + 94y
                            mole fuel
  Dividing by the molecular weight of  the fuel yields  the mass  of exhaust
  gases  per  mass of  fuel,  assuming 15  percent 02  in  the  exhaust stream
                                  C-176

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                          ITI dry exhaust , 492x + 94y                   (12)

                            m fuel        12x + y
  By multiplying  this  value  by the brake-specific fuel consumption (BSFC)


  the brake-specific exhaust flow 1s determined.
                       dry exhaust - BSFC
^2x + 94y)
 TZxTy  /
                                             ZxT                    U3;
        The ratio of exhaust mass flow to exhaust  gas  molecular weight can


 now be determined.   From equation (13)  and  (7):
                                            BSFC x  4?2x *
             Brake specific exhaust flow    	\ '2x + y

             Molecular wt. of exhaust gas *  (  492x +~—^      (14)
 This  reduces to
                         BSFC x (16'6ftxV;29y)                    (15)
Substitution Into equation (1)  and converting  to  parts  per million  (ppm)

gives:
                                C-177

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the limits of 5 g/hp-hr for dual fuel, 9 g/hp-hr for gas,  and 7  g/hp-hr
for diesel, (and the above fuel properties) the following  NOX    emission
limits were determined:
       654 ppm for gas
       518 ppm for diesel
       370 ppm for dual-fuel
       As  a check  of  the  validity of the conversion method, all  raw ppm
versus BSNO   data  was plotted (corrected to 15 percent 02).  By using
           A
equation (16),  the average fuel consumption,  and a mean value of the
hydrogen/carbon  ratio the average conversion curve was determined and is
 shown in Figure C-34.  The standard deviation (expressed  in percent)
 between  this curve and the actual data was found to be 10 percent.
                                   C-182 .

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C.6    STATISTICAL ANALYSIS FOR ALTERNATIVE EMISSION LIMITS
       In selecting the numerical emission limits for each fuel type,  it
was necessary to determine the tradeoffs associated with standards of
performance based on each of the three  alternatives of  applying a 40
percent  NO  emissions  reduction.  Thus,  a  statistical approach was
          /\
considered the most  logical  approach.
       The uncontrolled  NOV  emission  from  each engine fuel  type were
                           A
 assumed  to follow a  theoretical  normal  distribution.   Figures C-35,  C-36.
 and C-37 illustrate  the theoretical normal distribution curves for diesel,
 dual-fuel,  and gas engines, respectively.   Note that the curves have
 truncated ends at positive points on the  axis as no engines emit 0
 g/hp-hr.  The areas under each curve represent the population if each
 engine  fuel type emitted up to a particular  limit.  The mean values which
 bisect  the normal distribution were  assumed  to be  the  sales-weighted
 uncontrolled  average  NOX  emission  levels  discussed in  Section 4.3.4  and
 the  standard  deviations,  for  each  fuel type  were assumed  to be equal  to
 the  standard  deviation  calculated  from the  data  base  in Appendix C.   That
  is,  the standard deviation is not  sales weighted as no such information
  was  available.   If  the standard deviation were calculated for increasingly
  Targe samples and increasing small class intervals, its value would be
  expected to approach the theoretical  standard deviation.  The data
  tabulated in Appendix C was used  to calculate sample  standard deviations
  for each fuel type:  (1) Gas,  a-  4  g/hp-hr,  (2) Dual-fuel,  a =  3.2
  g/hp-hr, and  (3) Diesel,  
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       Standards of performance based on each of the three alternatives
were analyzed relative to the theoretical normal distribution  curves  to
determine:  (1) the percentage of the engines that would  have  to  reduce
NO  emissions by 40 percent or less  to meet  the  standard;  (2)  the
percentage of engines  that would be  required to  do  nothing  to  meet the
standard; and  (3)  the  percentage of  engines  that would be required to
reduce  NO  emissions by  more  than  40 percent to  meet the standard.  The
          X
results are  illustrated  on  each  figure  and summarized in Table C-93.
        As a  check  on  the accuracy  of the assumption of a normal
distribution,  the actual data base in Appendix C was  analyzed relative  to
 percentages  of engines for each alternative determined from the  normal
 distribution.   The results are tabluated in Table C-93 as the numbers  in
 parentheses.  The actual sample values  show very good agreement  with the
 values  determined by  the pure normal distribution  approach.
         Thus,  it can be  concluded  that the  assumption  that  the uncontrolled
 NOX emission  levels,  for  a given  fuel type, follow a theroetical normal
 distribution  curve  is essentially true  and the  statistical  approach is
 deemed to be  a valid  approach.
                                    C-188

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TABLE C-93.  SUMMARY OF STATISTICAL ANALYSES OF ALTERNATE EMISSIONS LIMITS




                                        GAS ENGINES
Alternative
Standard
Percent meeting standard
with f_40 percent control
Percent required to do
nothing to meet standard
Percent required to apply
40 percent control to
I II III
17 9 11
99 (100) 50 (50) 84 (91)
69 (67) 7 (6) 18 (9)
1 (0) 50 (58) 16 (9)
DUAL-FUEL ENGINES
Alternative
Standard
Percent meeting standard
with £40 percent control
Percent required to do
nothing to meet standard
Percent required to apply
40 percent control to
I II HI
9 5 7
98 (100) 54 (44) 87 (89)
62 (67) 18 (4) 48 (44)
2 (0) 46 (56) 13 (11)
DIESEL ENGINES
Alternative
Standard
Percent meeting standard
with < 40 percent control
Percent required to do
nothing to meet standard
Percent required to apply
40 percent control to
I II in
11 7 9
98 (100) 56 (63) 86 (90)
50 (65) 14 (18) 29 (45)
2 (0) 44 (37) 14 (10)
                                C-189

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C 7    COMPARISON OF SMALL-BORE, AUTO ENGINE EMISSION CONTROL TECHNIQUES
       FOR LARGE BORE-STATIONARY 1C ENGINES
C.7.1  Introduction
       During  a review meeting  with EPA  in September 1977,  several
questions were raised concerning the  application  to  large-bore  stationary
engines  of control  techniques  that  have  been  shown  to  be effective on
 automotive engines.   In  addition, questions were  asked why catalytic
 reduction  of NO   (which  has been  successfully used  in  Japan) and water
                /\
 induction  (the primary N0x control  technique  for  stationary gas
 turbines)  were not alternative controls for stationary i, ^ngines.  This
 memo briefly  summarizes these three questions.
 C.7.2.1  Comparison of Control Techniques for Large-Bore Stationary
          and  Automotive Engines
         Essentially the same NOX control techniques  that  have been  used
 by  engine manufacturers to meet emission  regulations  for mobile sources
 are also effective when applied to  large-bore engines.   These  techniques
 include derating*, retarded  ignition or fuel  injection,  manifold air
 cooling (with turbocharging),  air-to-fuel ratio  changes, and exhaust gas
  recirculation.   Of these  controls,  retard (for diesel or dual  fuel
  engines)  and air-to-fuel  changes (for natural gas engines) are
  particularly effective when applied to large-bore engines.
         Nevertheless, inherent differences in the design and operating
  modes  of large stationary and smaller, mobile engines  have dictated
   'Derating  is  accomplished  by using  a larger  engine than necessary for a
    particular car.
                                    C-190

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   different approaches to exhaust emission control.  Figure C-38, which
   shows the effect of A/F ratio on exhaust emissions, can be used to
   illustrate this  point.   Typically,  spark ignition automotive engines are
   operated  at  slightly less  than  stoichiometric  A/F ratios.   This operation
   is  largely dictated  by  the difficulty  in closely  controlling the A/F
   ratios to  individual  cylinders within  these carbureted  engines.
  Therefore, A/F ratios must be maintained  richer than stoichiometric  to
  avoid detonation and misfiring.
         With the advent of strict emision'regulations (primarily  aimed at
  reducing  HC and CO emissions), automotive manufacturers concentrated on
  increasing the  A/F ratio (e.g.,  "lean burn" engines),  which, as
  Figure C-35 illustrates,  decreases HC and CO emissions  significantly and
  also  improves fuel  economy.  N0x  emissions,  however, increase initially
  as A/F  ratios are  increased beyond stoichiometric.   As emission
 regulations became  even more stringent,  additional  controls  were,
 therefore, required.  These controls  included exhaust gas recirculation
 (EGR) and  returning to richer A/F ratios to reduce N0x.   To compensate
 for the resulting increase in  HC and  CO emissions,  oxidizing catalysts
 were  added.   These catalysts also enabled automobiles to reach the more
 stringent  requirements for HC  and CO  that became mandatory in 1975.
 Improvements  in  carburetion  and mixing were also effective in optimizing
 exhaust emissions  over  a  range  of  loads  and speeds.
       Lage bore engines,  in contrast, typically operate  leaner  than
stoichiometric.  Consequently,  as shown  in  Figure C-35, NO  emissions
                                                          /\
                                 C-191

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  are  relatively  high,  but  HC  and CO emissions  are now low*.   These



  operating  conditions  result  from the need to  optimize fuel  consumption of



  large-bore  engines  because they see high  usage,  high load service.



  Therefore,  the  emphasis of exhaust emission control  for large-bore  engines



  is in reducing  NOX  emissions.   Although the same types of combustion



 modifications that  are effective  in  reducing  NO   from automotive engines
                                                A


 could be used on large stationary  engines, the selection  of  optimum



 controls and the direction and  degree of  application  of the  selected



 controls is different due to differences  in uncontrolled  A/F  ratios  and



 fuel  charging methods.



 C.7.2.2  Catalytic Reduction



        As of this date no large-bore engine manufacturers are using



 catalysts to reduce NO  emissions.  NO  reduction catalysts, until
                       ^               A


 1977, have  not been used  on  gasoline or diesel vehicles either.  The



 catalysts that have been  and  are still  currently in use on automobiles are



 primarily oxidizing catalysts,  whose purpose  is  to lower HC and CO



 emissions.   Recently,  however,  three-way catalysts have been developed for



 the reduction  of HC, CO,  and  NOV emissions and the first commercial
                                A


 application  was  for  a  1977 Volvo sold in California.   (Three-Way



 Conversion Catalysts — Part  of  the New  Emission  Control System; SAE



 Paper, 770365).  These three-way catalysts are similar to  the earlier



 oxidizing catalysts  (precious metals  coated on monoliths or  pellets)  with
*The exceptions to this generalization are those  large-bore engines which

 are naturally aspirated or carbureted; these units have emissions

 characteristics which are similar to automotive  engines since they operate

 at A/F ratios closer to stoichiometric.
                                 C-193

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the addition of rhodium which selectively reduces NOX when the A/F ratio
1s maintained very near sto1ch1ometr1c.  These conditions exist  1n
automotive exhausts but not in the discharge from large bore engines.
Therefore, this control approach shows  little promise for large  bore
engines.
       As discussed on page 4-139 of  the SSEIS,  however,  an
ammonia/catalyst  N0¥  control  system has been  suggested  in the  literature
                   J\
and  1s based  on the successful  application  of  this  technique  to  nitric
acid  plant  tail gases and  a  number  of large stationary  combustion sources
in Japan.   An excellent  discussion  of technique is  presented  in  a paper
"Status  of  Flue Gas Treatment Technology  for Control of NOX and
Simultaneous Control  of  SOX  and NOX", Mobley, J. David, and Stern,
Richard D., U.S.  Environmental Protection Agency, Report No.
 EPA-600/7-77-033C.  This paper is an excellent review of this technology,
 its effectiveness, and its costs.  Based on information in this  report it
 would appear that selective catalytic  reduction  is  a technically feasible
 approach for gaseous fuel engines, but the fouling  (particulate)  and
 catalyst-poisoning (sulfur) problems  associated  with oil or coal
 combustion would  require further development.   Moreover, this approach
 appears to be very expensive.   If the published costs  are  extrapolated for
 1C  engines,  the  data indicate that  annual  ownership and  operating costs
 would  increase from  between  3 to 30  percent.   These costs  are based on
 sources  that are at  least  an  order  of magnitude larger than  a typical
 engine  installation.  In  addition,  the costs of maintenance  and catalyst
  replacement  may  be  somewhat understated  for smaller sources,  such as 1C
  engines.   Thus,  it  is probable that the actual costs for an engine
  application would be even greater than these estimates.
                                   C-194

-------
          A similar N0x reduction scheme has been developed by Exxon
   (Thermal Denox Process) for N0x reduction from stationary boilers and
   furnaces.   In  this process, ammonia is injected into the flue gas at
   locations  where the temperature exceeds 1500°F.  There appears to be no
   application  for this  process  to 1C  engine exhausts,  however,  since exhaust
   temperatures are  generally  less than  1000°F.
   C.7.2.3  Water  Induction
         As discussed in the  SSEIS (Section 4.4.7), water  induction  has  been
   investigated by four large bore engine manufacturers (White Superior,
  Ingersoll-Rand, Cooper, and GMC/Electromotive).  All reported  serious
  concern about the feasibility of this technique based on observations of
  water in  the  crankcase and lubricating oil,  rapid build-up of mineral
  scale (untreated water)  around intake/exhaust valves and other components,
  and  combustion  deposits.   All  of the tests were of short duration (less
  than  25 hours of engine  operation),  and  manufacturers believe  much  longer
  tests  (2000 to 8000  hours) would be  necessary to establish  the  effect of
  water  induction  on wear rates  and operating reliability.
        In addition to these manufacturers, two  smaller bore engine
 manufacturers, GMC/Detroit Diesel and Caterpillar, have reported  tests of
 water induction  in truck-size diesel  engines.   Caterpillar believes the
 technique  is viable if  the water is  treated for freeze protection and
 mineral content.   Caterpillar tests  showed significant deposits, but they
 concluded  these  could be  prevented by demoralizing  the water.
 GMC/Detroit Diesel  also experienced significant deposits  and  concluded
 that these deposits  originated  from condensation of combustion  products
 rather  than water minerals.   Based on their exprience, GMC/Detroit Diesel
concluded that water  induction was not feasible  in their 2-stroke  designs.
                                  C-195

-------
C.8  Determination of Sales-Weighted Average Uncontrolled CO and HC
     Emissions
     Since the source of variability caused by engine design cannot be
specifically Identified, a procedure 1s required to characterize uncon-
trolled CO and HC emissions levels of engines which are sold for simi-
lar applications.
     The procedure adopted here is to compute a weighted, average
uncontrolled emission level for engines in  the diesel, dual-fuel, or
natural gas categories.  The three weighted levels are based on  sales
of engine  horsepower during the past five years for domestic applica-
tions.  Sales  of horsepower to standby  services were  excluded  from  this
computation,  since  engines sold for standby applications  will  be exempted
 from standards of performance  (see  Chapter 9).
      The  sales-weighted averages  for diesel, dual-fuel,  and natural  gas
 engines are presented  in Figures  C-39(a-f), which also show each
 manufacturer's CO and  HCt data.   The weighted average uncontrolled CO
 level for diesel engines is  2.9  g/hp-hr; for dual-fuel units,  2.7 g/hp-
 hr; and for natural gas engines,  7.7 g/hp-hr.  The weighted average
 uncontrolled HCt level for diesel engines  is 0.3 g/hp-hr; for dual-fuel
 units, 2.8 g/hp-hr; and for natural gas engines, 1.8 g/hp-hr.
                                  C-196

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                          REFERENCES FOR APPENDIX C
 (1)  Storment, 0.  0.  and K.  J.  Springer.  Assessment of Control Techniques
 Report AR-8§4   $11*19™  LoCOrn°t1ve En9ines-  Southwest Research Institute

 (2)  DEMA Exhaust  Emission Measurement Procedure for Low and Medium Speed
 CleveUnd?°Oh1oti0S E5§1nei974D1eSe1 Eng1ne Manufacturer* Association.
 r«nne'  Fc  ?'  a?drKl V-.Be19htol (Cooper-Bessemer).   Effect  of  Operating
 Conditions  on Exhaust Gas Emissions of Diesel, Gas Diesel, and Spark Ignited
 Stationary  Engines.  Unpublished Cooper-Bessemer Co.  Report   Presented
 at eas Compression  Shortcourse, Norman,  Oklahoma, Fall  1973.
 (4)  McGowin,  C. R., F. S. Schaub, and R. I.  Hubbard.   Emission Control
 rnn3iHn^°nJrLl??"Dtroke^park;G!s,Enf1ne b* Modification of Operating
 Conditions, AGA/IGT Proceedings 2nd Conference on Natural  Gas  Research
 and Technology, Atlanta, Georgia.   1972.
 (5)  Hanley,  G. P., Marketing and Technical Data on Reciprocating Engines
 for Stationary Application.   General  Motors Corp.   January 24,  1974.
              f-' ?' and/;.V'  Bei9htol.  Effect of  Operating Conditions
     iS?Sb«iF' c'  ^°^er"?ecsemer)' M6^0^ of Reduction of NOX Emissions
      a9°WSPd DeS1E         U'S' *"
                                                                 (Acurex/

                  M.  P. Thompson  (White Superior) to D. R.  Goodwin (EPA),

pJlLrf5!?*!*  *',C;  Em1"ion Reduction Study on a Carbureted  Natural  Gas
Fueled Industrial  Engine.  White Superior Division.   White  Motor  Corporation.
                                     C-203

-------
(Presented at Annual ASME Meeting, Diesel and Gas Power Division,  New
Orleans, April 1975).

(12)  Letters from N. S.  Cox (Waukesha) to G. R.  Offen (Acurex/Aerotherm)
November 20, 1974 and June 16, 1975.

(13)  Caterpillar Tractor Co.  Data submitted to Acurex/Aerotherm, August
27, 1974.

(14)  Brisson, B.s et al., A New Diesel Combustion Chamber -- The Variable
Throat Chamber.  SAE Paper 730167.  1973.

(15)  Letter from M. P. Thompson (White Superior) to D. R. Goodwin (EPA),
August 3, 1976.

(16)  Letter from R. Sheppard (Ingersoll-Rand) to D. R. Goodwin (EPA),
June 17 and September 22, 1976.

(17)  Letter from A. R. Fleischer (DeLaval) to D. R. Goodwin (EPA),
July 30, 1976.

(18)  Letter from R. D. Smalley (White Alco) to D. R. Goodwin (EPA),
July 29, 1976.

(19)  Letter from W. E. Snyder  (Waukesha) to D. R. Goodwin (EPA),
July 20, 1976.

(20)  Letter from F. S. Schaub  (Cooper)  to D. R. Goodwin  (EPA), August
4,  1976.

(21)  Letter from C. L. Newton  to D. R.  Goodwin  (EPA), September  10,  1976.

(22)  Letter from R. D. Henderson to Fred Porter  (EPA), March 17, 1977.

(23)  "Revised Heavy Duty Engine Regulations for  1979  and Later Model
Years,"  Federal  Register,  Volume  41, No.  101, May 24,  1976.

(24)  Coordinating  Research  Council  (CRC),  "Effect  of  Humidity of Air
Intake  on  Nitric Oxide Formation  in Diesel  Exhaust," CRC  Report 447,
December 1971.

 (25)  Krause,  S. R., "Effect of Engine Intake-Air Humidity,  Temperature,
and Pressure  on  Exhaust  Emissions,"  SAE  Paper 710835.

 (26)   Ibid.

 (27)   "Revised Heavy Duty Engine  Regulations for 1979  and Later Model
Years," Op_.  C1t.

 (28)   Krause,  Op,.  Cit.

 (29)   Ibid,
                                       C-204

-------
  (30)   Ibid.


  (31)   Ib1_d.


  (32)   Ib1_d.


  (33)   Ibid.



                                        E"9lni



                                            of


  (36)  State of California, A1r Resources Board,  1973,  "California Exhaust
 Emission Standards for Gasoline Powered Motor Vehicles," Proposed,  November
 13, 1970.



 (J7ii  E2Vi1ip°I?int!1  Protect1on ASency (40 CRF Part  85,  Subpart  A),  "Control
 of Air Pollution from New Motor Vehicles and  New Motor  Vehicles Engine,"
 (Notice of Proposed  Rule  Making),  February 1971.


 (38)  Scott,  Op_. C1t.
      .1  P'  5;^'Humii!1cLE!!fects  on  En91ne  N1tric Ox1de  Emissions
 at Steady-State  Conditions,"  SAE  Paper 700467.


 (40)   Krause,  0£. C1t.


 (41)   ibid.


 (42)   Ibid.


 (43)   Brown, et  al., 0£. C1t.


 (44)   Ibid.


 (45)   Scott, 0£. Clt.
fiFny^!; "El!l1ssi;nACont'"01 of a Stationary Two-Stroke Spark-

Co^plny Rlport%972"   n    Operat1n9 Conditions," Shell Development




                     R' Fle1scher (0eLava1 Turb1ne Inc«) ^ D. R. Goodwin
(48)  Coordinating Research Council, Op_.  Cit.
     -r' S: 5"  Merr1on,  D.  F.,  and Green,  G.  L.  "Effect of Inlet
Air Humidity and Temperature on Diesel  Exhaust Emissions,"  SAE Paper 730213.



      "Ren1ser^eavy  Duty Eng1ne  Regulations  for 1979  and Later Model
     .    up.  Clt.
                                   C-205

-------
(51)   Krause, Merrlon, and Green, Op_.  C1t.
(52)   Coordinating Research Council, OJD. C1t.
(53)   Krause, Merrlon, and Green, 0£.  C1t.
(54)   Coordinating Research Council, Oj>. C1t.
(55)   Krause, Merrlon, and Green, Op_.  Cit.
(56)   Touchton, G. L. and N. R. Diebeluis, "A Correlation of Nitrogen
Oxides Emissions with the Gas Turbine Operating Parameters," ASME Paper
76-GT-14.
(57)  Shaw, H., "Effect of Water on Nitric Oxide Production in Gas Turbines
Combustors," ASME Paper 75-GT-70.
(58)  Blazowski, W. S. and D. E. Walsh, "Prediction of Aircraft Gas Turbine
NOx Emission Dependence on Engine Operating  Parameters and Ambient Conditions,"
AIAA Paper 73-1275.
(59)  Vaught,  J. M. "The  Effect of  Inlet Temperature and Pressure on an
Industrial Turbine Engine Exhaust Emission," ASME Paper 75-WA/GT-ll.
(60)  Hung,  W.  S. Y., "An Experimentally  Verified NOx Emission Model for
Gas Turbine  Combustors,"  ASME  Paper 75-GT-71.
(61)  Marzeski, J. W. and W. S.  Blazowski,  "Ambient Temperature and Pressure
Corrections  for Aircraft  Gas Turbine  Idle Pollutant Emissions," ASME Paper
76-GT-130.
(62)  Hung,  Cj£. Cit.
(63)  Touchton and Diebeluis, £p_. Cit.
 (64)   Ibid.
 (65)  Krause,  Merrion,  and  Green, Op_. Cit.
 (66)  Gas Turbine International, May-June 1974.
 (67)   Ibid.
 (68)  Krause,  Merrion,  and Green, Op_. Cit.
 (69)   Private communication between S. B. Youngblood  (Acurex/Aerothenn)
 and J.  McDermon (EPA),  October 1976.
 (70)   Ibid.
 (71)   Krause, Merrion,  and Green,  Op_. Cit.
                                       C-206

-------
  ^I2l  ?u>  T;  ??d  Kl  J>  McAulay»  "Predicting Diesel Engine Performance
  at Various Ambient Conditions,"  SAE Paper 730148.            romance



  ancM  ^ges*"18' F' A"  Combust1on Theory. Add1 son-Wesley, Chapters 3
  (74)  Wilson, R  P., Jr., E. B. Mu1r and F. A. Pell1cc1ott1, "Emission

  Study of  a Single-Cylinder Diesel Engine," SAE Paper 740123.


  (75)  Williams, Op_. Cit.



                   R< W< Sheppard dngersoll-Rand)  to D.  R.  Goodwin (EPA),
  oMeSJSHM^^nS^n'I^n?0"";1] £CRC)  "Co°Perative Evaluation  of  Techniques
 for Measuring NO and CO in Diesel  Exhaust:   Phase III,"  CRC  Report, 1972.




                                                         "  SAE Recommended
 (79)  Perez,  J  M.,  L.  C.  Broering,  and  J.  H.  Johnson,  "Cooperative Evaluation

 of Techniques for Measuring NO  and CO  (Phase  IV  Tests)," SAE  Paper 75204
 nSi n?oord.1;at1n? Research Council (CRC) "Cooperative Study of Heavy

 Duty Diesel Emission Measurement Methods," CRC Report 487, July 1976.



 (83)  Perez, Broering, and Johnson, Op_. C1t.



 (84)  TRW Systems Group, "A Study of Mandatory Engine Maintenance for

 Reducing Vehicle Exhaust Emissions, Volume VI: A Comparison of Oxides

 of NUrogen Measurements," CRC APRAC CAPE 13-68-12,  July 1972.


 (85)  Krause,  Merrion, and Green, £p_.  Cit.


 (86)  TRW Systems Group,  Op_.  Cit.



 (87)  Tuttle,  J.  H.,  R.  A.  Shisler,  and A. M.  Mellor,  "Nitrogen Dioxide

Formation in Gas  Turbine  Engines:  Measurements and Measurements Methods  "

Purdue University Report  No.  PURDU-CL-73-06, December  1973      |viei:noas»


(88)   Ibid.
                                     "Instrumentation for the Determination

                                               Emi'ssions'" Volume I.
                                     C-207

-------
(90)  Maahs, H. G., "Interference of Oxygen, Carbon Dioxide,  and Water
Vapor on the Analysis for Oxides of Nitrogen by Chemilumlnescence.
(91)  Matthews, R. D., R. F. Sawyer, and R. W. Schefer, "Interference in
Chemilumlnescent Measurement of NO and N02 Emissions from Combustion Systems,
Draft of Paper Submitted to Combustion and Flame, Fall 1976.
(92)  Slgsby, J. E., Jr., et al., "Chemlluminescent Method for Analysis
of Nitrogen Compounds in Mobile Source Emissions," Environmental Science
and Technology, Volume 7, No. 1, January 1973.
(93)  Coordinating Research Council (CRC),  "Cooperative Study of Heavy
Duty Diesel Emission Measurement Methods,"  CRC Report 487, July 1976.
(94)  Tuttle,  Shlsler, and Mellor, Cjp, Cit.
(95)  TRW  Systems  Group, Op_, C1t.
(96)   Ibid.
(97)   Clemens, W.  B.  (EPA/Ann  Arbor),  "Impact on  Existing Standards  Due
to Proposed Instrumentation  Changes  in  the Heavy Duty Federal Test  Procedure,
Interoffice Memo,  September  18,  1974.
(98)   Perez,  Broering,  and  Johnson,  Op_.  Cit.
 (99)   Krause, Merrion,  and  Green,  Op_.  Cit.
 (100)   Op_. Cit.,  Reference  93.
 (101)   Personal comunication between S. B. Youngblood (Acurex/Aerotherm)
 and W. B.  Clemmens (EPA/Ann Arbor), July 22,  October 19, and November 1,
 1976.
 (102)   Ibid.
 (103)   Schaub, F. S. and K. V. Beightol,  "NO* Emission Reduction Methods
 for Large Bore Diesel and Natural Gas Engines," ASME Paper 71-WA/DGP-2.
 (104)  OJK Cit.
 (105)  TRW Systems Group, Op_. Cit.
 (106)  [bid.
 (107)  0_p_.  Cit.,  Reference  101.
 (108)  Ibid.
 (109)  Ibid.
 (110)  "Revised  Heavy Duty  Engine Regulations for 1979  and  Later Model
 Years," Op_.  Cit.
                                       C-208

-------
  (Ill)  Diesel Engine Manufacturers Association (DEMA), "DEMA Exhaust
  Measurement Procedure for Low and Medium Speed Internal Cornbustio! ! E

                          °C°'  and N° tn De1Se1  ExhaUSt'" SAE
                ]  !?0t0r?  Corporation Statement on Draft SSEIS for Stationary
                Internal  Combustion Engines," May 14,  1976.         ««-'unary
  (114)  Op_. Cit. . Reference  93.
  (115)  °R- £21.. Reference  101.
  (116)  TRW Systems Group, Op_. Cit.
  (117)  Tuttle, Shiser, and Mellor, Op_. Cit.
  (118)  Schaub and Beightol, Op_. Cit.
  (119)  Clerrtmens, Op_. Cit.
 (120)  Ibid.
 (121)  0£.  Cit..  Reference 101.
 (122)  Ibid.
 (123)  TRW  Systems  Group,  Op_.  Cit.
                                                  a"d °' R' Goodw1n  -
(127)  Schaub and Beightol, OJD. Cit.
(128)  0_£.  Cit..  Reference 126.
            0rM»   R?SeauC!; Counci1 (CRC)' "Cooperative Evaluation of
         1975   Measur1n9 H^rocarbons in Diesel Exhaust," CRC Report 471,
                                     C-209

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                                  GLOSSARY
  aftercooler
 air-cooled
 air injection




 air-to-fuel  ratio


 annu.a!1zed  cost


 baseload


 BDC

 blower scavenging



 bore

 bottom dead center
brake horsepower
(bhp)
 - a heat exchanger used to cool inlet air that has
    passed through a turbocharger.  Also referred to as
    an Intercooler (see Figure 4-32).

 -- a method of engine cooling, often used on small
    engines.  A1r 1s sucked or forced over the engine (by
    an engine-driven fan) transferring heat from the
    engine block.  F1ns are generally used to conduct heat
    away from the combustion chambers and increase the
    area available for heat transfer.

 -- an emission control technique in which air is pumped
    (injected)  into the exhaust manifold to complete the
    reaction of any unburned fuel  and CO which is still
    present.

 - a  ratio  of  the mass flowrate (g/hr)  of  air into an
    engine to the mass  flowrate of fuel  (g/hr).

 -- initial  costs,  or  the sum of initial  and  operating
    costs, expressed as an annual  charge.

 — continuous  operation, generally  considered to be  8000
    hr/yr.

 --  see bottom  dead center.

 —  a method  of charging the cylinder of an engine with
   air in which a low-pressure blower driven by the
   engine forces air into the cylinder.

— the diameter of the cylinder of an engine.

-- position  of  the piston when it is at the bottom of the
   cylinder; corresponds to maximum  available gas volume.

-  the power delivered by the engine shaft at the output
   end.   The name is derived from the fact that it was
   first  measured by the power  consumed in  a  brake
   attached  to  the output shaft.   Brake horsepower  equals
                                  G-l

-------
brake mean
effective pressure
(bmep)
brake specific


carburetor



catalytic converter --
 cetane number
 chemiluminescent
 analyzer

 compression
 ignition (CI)
  compression ratio
  (00
  connecting  rod



  continuous  rating

  cooling system
  total  power delivered by the pistons  less losses  and
  power  used to drive auxiliaries (fan,  pumps,  etc.).

  the hypothetical  constant pressure that would have
  to be  exerted on  the head of the piston during the
  entire stroke to  generate the same torque as  is
  actually generated by the engine.  Hence, frequently
  used synonymously with torque.

  emissions expressed on the basis of power output,
  i.e.,  emissions g/hp-hr.

  a device on a spark ignition engine which controls the
  flowrate of air and fuel and mixes them in the proper
  proportions for combustion.

  a device which uses  a catalyst  to promote a reaction
  that  alters the chemical composition of the gas
  passing through it.  Oxidation  type converters change
  CO  and HC  to  C02  and H2° using  a  precious metal
  catalyst,  such as  platinum.  Reduction  catalysts  are
  used  to reduce NO  to N2 and 02-

  a reference  number for  compression ignition  engine
  fuels.  Higher numbers  indicate better  ignitability
   and better antiknock characteristics.
— a
device used to measure NOx emissions,
— one of two methods of initiating combustion in the
   engine cylinder.  In CI engines, the air charge is
   introduced into the cylinder and compressed, thereby
   raising its temperature above the auto-ignition
   temperature of the fuel (temperature at which the fuel
   ignites spontaneously).  Fuel is then injected into
   this hot compressed air and ignites spontaneously.
   All diesel and dual fuel engines are compression
   ignited.

-- ratio of the  volume  in the combustion chamber when
   the piston is  at  the bottom of  the stroke to that when
   the piston is  at  the top.

— a  rod which connects the piston to the  crankshaft and
   permits  the reciprocating motion of  the  piston to be
   transferred to rotary  motion  by the  crankshaft.

--  see rating.

 — the system by which  combustion  heat  is  removed from
    engine  block.  This  system  may  consist of  a water
    jacket  through which a liquid is circulated to remove
                                     G-2

-------
 cost effectiveness  —
 crank case blowby



 crankshaft



 crude

 cylinder Uner


 den1tr1f1cation


 derating


 desulfurlzatlon



 digester gas


 direct Injection

 displacement



 distillate


 dribble


dry
    heat from the engine and a radiator, cooling tower, or
    heat recovery system to remove the heat from the
    liquid before It 1s redrculated through the water
    Jacket.  It may also consist of fins to conduct heat'
    away from the combustion chambers and a fan to move
    air past these fins to remove the heat from them (see
    "air-cooled"),

    ratio of the cost to reduce a pollutant from an engine
    to the amount of pollutant removed ($/kg),

    unburned fuel, combustion gases,  and lubricating oil
    which escape from the cylinder past the piston rings
    into the crankcase and are then vented.

    the shaft that receives engine power from the
    reciprocating motion of the pistons  and delivers 1t as
    rotary motion.
 -- unrefined oil.

 -- a steel  Uner Inserted Into the cylinder.   It can  be
    removed  and replaced after  excessive wear.

 -- the  removal  of  nitrogen  from fuel  during refining.
    Some removal  occurs  concurrently with sulfur  removal.

 -- a control  technique  which limits the maximum  load  of
    an engine  to  less then the  design  value.

 -- the  removal of  sulfur  from  fuel.   This occurs  during
    the  refining  of crude  on Into  light  distillates and
    gasoline.

 —  fuel  gas formed from sewage  sludge.   Primary
    constituents  are CH4 (methane),  C02,  and Hg.

 --  the  Injection of fuel  directly  into the cylinder.

 --  the  volume a  piston sweeps out moving from the bottom
    of the cylinder (bottom dead center, BDC)  to the top
    of the cylinder (top dead center, TDC).

 — a product of the refining of crude oil.  The most
    common distillates are No.  2 dlesel oil and gasoline.

~ the loss  of fuel from the injector  tip after fuel
   Injection.

~ refers to gas  measurements made under conditions  where
   water has been removed from  the gas before  the
   measure 1s made.  Also  gas measurements which  have  been
                                   6-3

-------
durability
exhaust gas
red roil at1 on
(EGR)
exhaust manifold
 field  gathering
 flame ionization
 detector (FID)

 fossil steam
 four-stroke




 fuel additive


 fuel-bound
 nitrogen

 fuel pump


 governor
  heavy duty mobile
  higher heating
  value
   mathematically adjusted  to  be  equivalent  to measure-
   ments made  on  water-free gas.

-- the ability of an  engine to operate throughout a
   normal  service life without excessive wear or failure
   of engine components.

« an emission control remote  technique whereby a portion
   of the  exhaust gases are retained 1n the cylinder
   (Internal EGR) or  are routed back to the engine Intake
   (external EGR) to displace  some of the Inlet air.

- an internally ducted casting which receives  exhaust
   products from the cylinders and transfers these
   products to the exhaust systems (see Figure 4-47).

-- collection of oil  or natural gas at the surface of a
   well (the well-head) into  the pipes  (feeder  lines)
   which  carry it to  the major pipelines.

-- an  analytical  instrument used to measure HC  emissions.


-- steam  for  electric utility power generation  produced
   from the combustion of  coal,  oil,  or natural  gas.

 - a type of  engine  which  requires four traverses  of  the
    piston in the cylinder  (two revolutions  of  the
    crankshaft)  per  power  stroke (i.e.,  to complete a
    cycle).

 -- a substance added to fuel, usually to reduce smoke
    from an engine.

 - nitrogen contained in the fuel rather than  in the air.


 -  device which pumps fuel to the fuel injection system
     or carburetor.

  —  device  which  controls  the amount  of fuel supplied to
     the cylinder  according to the  load  demand on the
     engine,  e.g., a  governor  is  used  to maintain a given
     speed (rpm)  under varying load in electric  generator
     applications.

  --  a term referring to vehicles over 6000-lbs  gross
     vehicle weight  (total  weight when vehicle  is fully
     loaded) subject  to federal emission standards.

  —  the  heat produced by  the  complete combustion of  a
     unit  quantity of fuel  (at standard conditions of
     temperature, pressure, and humidity) such  that the
                                     G-4

-------
phase
                                    products of comb"stion is in the liquid
horsepower
indirect injection —
the time rate of doing work.  One U.S. horsepower is
equal to 33,000 foot-pounds per minute.   (One US
horsepower equals 1.014 metric horsepower.)
  initial  cost




  injection rate


  injection timing




  injector


 injector rack



 intake manifold



 intercooler

 intermittent rating

jacket water



knock

lean
                       mph                               "son  chamber,  or
                       antechamber,  where  combustion  commences  in  an oxygen
                       deficient  environment  before expanding into the
                       cylinder for  completion of  the  combustion in the
                       presence of excess  oxygen  (see  Figure 4-42).

                       the purchase  price  of  the engine,  including all
                       auxiliaries necessary for its operation  (e.g.,

                                     etc.P' afterC°°1er> Carting motor,
                         1ntroduced into
                                                                    cylinder
                      the time  measured in degrees of crankshaft rotation,
                      that it takes for fuel  to be admitted into the
                      cylinder.   Start of injection (in degrees  before TOO
                      is an important parameter in emissions  control.

                      Figure  ^injects  fuel  int° the cylinder (see


                      a  mechanical  linkage  controlled by the  governor  which
                      determines  the  pressure  of the fuel supplied by  the
                      fuel  pump to  the  fuel injector.               y

                      internally  ducted casting that  distributes  incoming

                             an   ^ m'XtUre  1nt° the           ™
                  -- see aftercooler.

                  ~ see rating.

                  - engine cooling water that circulates from a cooling
                     tower or radiator through cavities (or iacketO  in th*
                     engine block.                           j«.*ets>y  in tne


                  -- premature ignition of fuel  in  cylinder of an  engine.

                                              mixture  which  contains
                     burn  all  th  f   1	"  lv""'I
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low sac nozzle
injector


lower heating value —
major overhaul
 manifold air
 temperature cooling
 (MAT)

 maximum rating

 minor overhaul
  a fuel injector with a minimum of volume beneath
  the injector nozzle, thus reducina injector dribble
  and HC emissions (see Figure 4-55).

  the heat produced by the complete combustion of a unit
  quantity of fuel (at standard conditions of
  temperature  pressure,  and humidity  such that the
  Serin the products  of combustion  is  in the vapor
  phase.

- an overhaul  which  generally  includes removal  and
   replacement  (or reconditioning)  of the  cylinder
   liners,  pistons, rings, valves,  fue   pump,  and
   crankshaft.   The engine is frequently removed from the
   installation to perform this overhaul.

- a control  technique based on lowering the intake air
   temperature.  Usually accomplished with an intercooler
   (see Figure 4-32).

-- see  rating.

- an overhaul which  generaly  includes replacing
   rings, valves,  injectors  or spark p ugs, and
   occasionally  pistons.  This overhaul  is> usual y
    performed without  removing  the  engine  from its
    installation  and  at more  frequent intervals  than  major
    overhauls.
  naturally aspirated  ~
  nondispersive
  infrared analyzer
  (NDIR)

  nonpropulsive
   nuclear  steam
    a type of air charging whereby the f'st™
    into the cylinder as it travels to the bottom of the
    cjl?nder.  No? turbocharged, supercharged, or blower
    scavenged.
  —  an  instrument used to measure CO and C02*
     an  application where  the  engine  is  never  used  to move
     The structure or  device on which it is mounted.

     steam (usually for electric generation)  produced  by
     heat from nuclear reactions.
   operational  change   --
   original equipment
   manufacturer (OEM)
     a change in engine operation which requires only an
     adjustment of given operating conditions but no
     hardware additions - e.g., ignition timing.

     a firm which, in this case, buys an engine from an
     engine Manufacturer  and incorporates It into a product
     of which the  engine  is only a component --  e.g.. J
     portable compressor,  which  is usually assembled by an
                                      6-6

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  overhaul
  oxidation
  paramagnetic
  analyzer

  peak cylinder
  temperature

  pilot oil
 piston crown

 piston ring



 ports
 precombustion
 chamber

 physical change
quenching


rating
                       Worn  arts 1n an
                                                                    usually
    ariHiHnn J     s document»  oxidation refers to the
    addit on of oxygen to a molecule  by a chemical
    reaction, as when CO combines  with oxygen to form CO*
    (The more general definition is the loi  of electron!'
    by a reactant in a chemical reaction.)      eie"rons


                                 oxygen content of


 -- the^maximum  temperature  in the cylinder  during  combus-


 - a  small  amount  (<10 percent by heating value) of

    .trX. ofU6a  duna?.C^eVLaginTtoend^tethteheC°^sreeoSuSrn


 --  the upper surface of the piston.


 ""  p'iston/V^sJjnTin'gstlal  th^cif0 a-9r°°Ve in th6
   filling the gap between  the pistol and^he^iUer.^


 "" fSl^ent'e^the^ Cf1-irfder  liner though which air and
-- see indirect  injection.
                                                         °PP°Sed
   the cooling below the combustion point  of  fuel which
   has impinged on the walls of the cylinder.

   brake horsepower output of the  engine.  Reported
   either as continuous (power that Ingine cSTdeflver
   continuously),  intermittant (power that engine can
                                 6-7

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reactivity
(photochemical)

reduction
 residence  time
 residual
 retard
 rich



 rpm


  sac


  scrubber



  smoke

  spark ignition (SI)
   spark timing


   squish lip
 potential of a hydrocarbon compound to react with
 other species in the atmosphere to produce smog.

. when used in this document, reduction refers to the
 removal  of oxygen from  a molecule by a chemical
 reaction, as when NO is reduced to N2 and 09 In the
 presence of a catalyst.   (The more general definition
 is  the  gain of  electrons  by a reactant in a chemical
 reaction.)

- the time interval  after ignition  during  which  the
  air-fuel mixture can  burn at  elevated temperature  and
  pressure.

- a heavy viscous oil,  often containing  large  amounts  of
  sulfur  (>1 percent by volume),  which remains  after
  distillation to produce other fuels.

- a NOX control technique wherein ignition of the fuel
  is delayed by delaying the spark [SI engines) or the
  start of fuel  injection  (CI engines) by several
  degrees of crankshaft  rotation.

- refers  to an air  and fuel mixture which contains  less
  oxygen  than  is  stoichiometrically necessary to
   completely burn all  the  fuel.

—  rotations  per  minute;  a  measure  of  the  engine
   crankshaft  rotational  speed.

-  the small  volume below the nozzle of  an injector  (see
   Figure 4-55).

- a device which removes a pollutant from an exhaust gas
   stream through absorption of the pollutant by the
   scrubber liquid.

 -- visible emissions from  an engine exhaust.

 - one  of two methods of initiating combustion  in the
   engine cylinders  (see also  compression ig;1*10"'-  ™
   SI  engines, an electrical spark  is generated across  a
   aao between two electrodes  at  the  tip  of  the spark
    plSg to ignite the  fuel-air mixture   .All gasoline and
    natural  gas fueled  engines  are spark  ignited.

 - the degrees of crankshaft rotation before top dead
    center (TDC)  at which the spark commences.

 - refers to a cavity shape in the piston head which
     gfnlrates squish, or radially outward motion of the
     air-fuel mixture.  Combustion is initiated  in this
     cavity.
                                      6-8

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   standby



   stationary



   sto1chiometr1c



   stratified charge





  stroke




  swirl





 TDC


 thermal  efficiency



 thermal  fixation



 thermal  reactor




 top dead center



 torque



 turbocharger
    a limited usage service, typically 200 hr/yr or less
    (e.g., emergency electrical generators)

    an  application in which the engine is never
    propel the structure  or

   the                  X&^l
   movement of the piston between thesTpoints
                                             "

—  see top dead center.
          s: sr»sss
       gases,  thereby reducing HC and CO emissiSn

  position of the piston when it is at top of the
  cylinder; corresponds to minimum available gas volume.
                  "" ^ncrla06 th1Ch US6S 3  centr1fV9al compressor to
                                 f'lCoourc  OT LilP l nf^r^m ^no JSTV*   TL***
                     »* «VHH BK       •          •"•••••>* I I I WWII I I ( 'U U1I   I rlfrJ
                     r^firTi fiV*ttor»^\w»^*. .•_.._  i  i            3 •» • i •  I I 1C
two-stroke
 pss ?; f9fs,±s SV^^T^ o
 crankshaft) per power stroke (i.e.. £ compute
                                                              of
                               G-9

-------
valve



valve camshaft



valve overlap



 volatility


 wet
 a device  which  opens  into the cylinder  to admit air or
 air and fuel  mixture  or to exhaust  combustion
 products.

 a shaft driven off the crankshaft having eccentric
 lobes which open the  intake and exhaust valves at the
 proper time.

 the interval,  in degrees  of crankshaft rotation,
 during which the intake  and exhaust valve are both
 open.

.  a  measure  of the ability of  a fuel to evaporate  at  a
  given  temperature.

-  refers to  the  existence of water vapor  in  an  exhaust
  gas  sample from water of combustion  and water
  contained  in the intake air.
                                      6-10

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fl7 REPORT NOT
,   EPA-450/2-78-125a
|4. TITLE AND SUBTITLE
   Stationary  Internal
   VT*4MS<{«UkWa. ^ . „ _ _ _ . *
                                                    REPORT DATA
                                                    the reverse before completing)

                                                                  J3. RECIPIENT'S ACCESSION NO.'
                                                     Stated:
    '. PERFORMING ORGANIZATION NAME AND ADDRESS'
      Standards Development Branch
      Emission  Standards  and Engineering Division
      Research  Triangle Park,  N. C.   27711

    12. SPONSORING AGENCY NAME AND ADDRESS

     DAA for Air  Quality Planning and Standards
     Office of Air,  Noise  and  Radiation
     u.  S.  Environmental  Protection Agency

   15. SUPPLEMENTARY NOTES
     TI_ £ _  .     .   . .
                  and
                                                                   5. REPORT DATE
                                                               8. PERFORMING ORGANIZATION REPORT NO.



                                                              J'1'O. PROGRAM ELEMENT NO."


                                                               TTTCONTRACT/GRANT NO."




                                                              13. TYPE OF REPORT AND PER.OD COVERED

                                                              "14. SPONSORING AGENCV CODE


                                                                EPA/200/04
                                                                      	

                                                                      environmental
                    DESCRIPTORS
                                   KEY WORDS AND DOCUMENT ANALYSIS
   Internal Combustion enqines Air
IB. DISTRIBUT ION STATEMENT"

   /n1,]?601 Availab1e  from EPA  library
   (MO-35), EPA,  Research  Triangle  Park
                                                                       TERMS
                                                  Oxides  Water  injection.
                                             1S.|ECURITY OLASS

                                              unrl^ti^ifiorl
                                             zo. SECURITY CLASS (Thispagef
     c,m 2220., ,R.V. 4.77)   PREV,OUS ED1TION (s OBSOLETE

^U.S.GOVERNMENTPRIhrriNGOFFICE;1979 -6*0-01* 3 9 0 7 REGION NO. 4
. OF PAGES

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US, Environmental Protection Agency
Region 5, library (PI-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, II  60604-3590

-------