REPORT ON REVISIONS TO
5TH EDITION AP-42
Section 3.4
Large Stationary Diesel
and All Stationary Dual-fuel Engines
Prepared for:
Contract No. 68-D2-0160, Work Assignment 50
EPA Work Assignment Officer: Roy Huntley
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Prepared by:
Eastern Research Group
Post Office Box 2010
Morrisville, North Carolina 27560
September 1996
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Table of Contents
Page
1.0 INTRODUCTION 1-1
2.0 REVISIONS 2-1
2.1 General Text Changes 2-1
2.2 Nitrogen Oxides, NOX 2-1
2.2.1 Uncontrolled NOX for Diesel Engines 2-1
2.2.2 Uncontrolled NOX for Dual-fuel Engines 2-1
2.2.3 Controlled NOX 2-3
2.3 Carbon Monoxide, CO 2-4
2.3.1 Diesel Fuel Engines 2-4
2.3.2 Dual Fuel Engines 2-5
2.4 Sulfur Oxide, SOX and Carbon Dioxide, CO2 2-5
2.5 Particulate Matter, PM and PM Sizing 2-5
2.5.1 Total PM 2-5
2.5.2 PM Sizing 2-7
2.6 Total Organic Carbon, TOC 2-7
2.7 Speciated Organic and Polycyclic Aromatic Compounds, PAH 2-7
3.0 REFERENCES 3-1
4.0 REVISED SECTION 3.4 4-1
5.0 EMISSION FACTOR DOCUMENTATION, APRIL 1993 5-1
298-130-79-07/REPORTS/SEC 3-4.RVS 111
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1.0 INTRODUCTION
This report supplements the Emission Factor (EMF) Documentation for AP-42
Section 3.4, Large Stationary Diesel And All Stationary Dual-Fuel Engines, dated April,
1993. The EMF describes the source and rationale for the material in the most recent
updates to the 4th Edition, while this report provides documentation for the updates written
in both Supplements A and B to the 5th Edition.
Section 3.4 of AP-42 was reviewed by internal peer reviewers to identify technical
inadequacies and areas where state-of-the-art technological advances need to be
incorporated. Based on this review, text has been updated or modified to address any
technical inadequacies or provide clarification. Additionally, emission factors were checked
for accuracy with information in the EMF Document and new emission factors generated if
recent test data were available.
If discrepancies were found when checking the factors with the information in the
EMF Document, the appropriate reference materials were then checked. In some cases, the
factors could not be verified with the information in the EMF Document or from the
reference materials, in which case the factors were not changed.
Four sections follow this introduction. Section 2 of this report documents the
revisions and the basis for the changes. Section 3 presents the references for the changes
documented in this report. Section 4 presents the revised AP-42 Section 3.4, and Section 5
contains the EMF documentation dated April, 1993.
298-130-79-07/REPORTS/SEC 3-4.RVS
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2.0 REVISIONS
2.1 General Text Changes
Text was added concerning emissions and controls based on information in the EMF
Document. Also, at the request of the EPA, metric units were removed.
2.2 Nitrogen Oxides. MX
2.2.1 Uncontrolled NOX for Diesel Engines
The 5th Edition contained an uncontrolled NOX emission factors of 3.1 Ib/MMBtu
(0.024 Ib/hp-hr) with an overall rating of "C." After reviewing approximately 25 emission
test reports, it was determined that there was sufficient NOX data from one report to update
the emission factor. This report contained data from five uncontrolled engines. This data
was combined with existing data in Table 4-la of the EMF Document and is shown in Table
1. There were data from a total of 24 engines (ranging in size from 610 hp to 7,313 hp) in
Ib/hp-hr units; however, there was insufficient data to convert five of these to Ib/MMBtu
units.
By combining the existing data with the new data, the uncontrolled NOX emissions
factor was essentially the same as in the 5th Edition, 3.2 Ib/MMBtu (0.024 Ib/hp-hr). Since
the Ib/hp-hr remained unchanged and the Ib/MMBtu only changed by 0.01 Ib/MMBtu, the
emission factors were not changed. However, due to the increased amount of data, the
overall rating was upgraded to a "B."
2.2.2 Uncontrolled NOX for Dual-fuel Engines
The NOX emission factor for uncontrolled dual-fuel engines was checked against
information in Table 4-2 of the EMF Document and was found to be in error. Table 2
presents the revised emission factor. The rating remained a "D."
2-1
298-130-79-07/REPORTS/SEC3-4.RVS
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Table 1
NOX Emission Factor Development for Uncontrolled Diesel Engines
Engine/Site
24
62
43
56
55
41
42
17
15
o
6
57
58
18
52
19
59
5
51
47
Kennecott
Alyeska
Alyeska
Alyeska
Alyeska
Engine Size
(hp)
610
711
1,100
1,300
1,336
1,650
1,650
2,200
2,410
2,475
2,675
2,800
3,300
3,631
3,900
3,900
4,300
4,880
7,313
2,079
2,105
2,803
2,105
2,803
Reference
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
EMF Table 4-1
3
o
J
o
J
3
3
Averages:
Standard Deviation
Number of Data Points
NOX
(Ib/MMBtu)
2.8
1.5
a
2.9
2.3
a
a
4.9
3.9
a
2.7
1.4
4.8
o o
J.J
a
2.4
3.6
2.8
3.3
2.2
4.3
3.8
4.5
4.0
3.2
1.0
19
NOX
(Ib/hp-hr)
1.9E-02
1.1E-02
3.8E-02
1.9E-02
1.6E-02
2.8E-02
3.2E-02
3.7E-02
2.5E-02
2.8E-02
1.9E-02
l.OE-02
3.2E-02
2.1E-02
2.6E-02
1.7E-02
2.4E-02
1.9E-02
2.1E-02
1.6E-02
3.0E-02
2.7E-02
3.1E-02
2.8E-02
2.4E-02
7.5E-03
24
Data Rating
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
A
A
A
A
A
B
a Insufficient data to calculate.
298-130-79-07/REPORTS/SEC 3-4.RVS
2-2
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Table 2
Revised Uncontrolled NOX Emission Factor for Dual Fuel Engine
Engine
61
16
6
Engine Size (hp)
711
2,410
8,658
Average
Revised NOX Emission Factor
Ib/MMBtu
2.45
2.66
3.12
2.7
Ib/hp-hr
0.016
0.017
0.020
0.018
2.2.3 Controlled NOX
The 5th Edition of AP-42 did not contain NOX emission factors for controlled diesel
and dual fuel engines. There was sufficient NOX data from one test report to develop an
emission factor for diesel engines controlled by ignition timing retard. This report contained
NOX data from 12 diesel engines ranging in size from 860 to 3,600 hp. The data used to
develop the controlled NOX emission factor is shown in Table 3. The controlled NOX
emission factor is 1.9 Ib/MMBtu (0.013 Ib/hp-hr) with an overall rating of "B".
298-130-79-07/REPORTS/SEC 3-4.RVS
2-3
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Table 3
NOX Emission Factor Development for Diesel Engines
Controlled by Ignition Timing Retard"
Engine Size (hp)
860
3,600
3,600
1,785
1,785
1,785
Unknown
1,785
1,350
1,350
1,625
860
Average
NOX Emission Factors
(Ib/hp-hr)
0.01
0.015
0.016
0.012
0.012
0.014
0.013
0.013
0.015
0.013
0.012
0.011
0.013
(Ib/MMBtu)
1.5
2.2
2.2
1.6
1.8
2.0
1.8
1.8
2.1
1.9
1.7
1.6
1.9
Data Rating
A
A
A
A
A
A
A
A
A
A
A
A
B
Data taken from Reference 3.
2.:
Carbon Monoxide. CO
2.3.1 Diesel Fuel Engines
The CO emission factors for diesel engines were checked against information in
Tables 4-la and 4-lb of the EMF Document and was changed from 0.81 Ib/MMBtu
(0.00529 Ib/hp-hr) to 0.85 Ib/MMBtu (0.0055 Ib/hp-hr) in order to correct a mathematic
error.
298-130-79-07/REPORTS/SEC 3-4.RVS
2-4
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2.3.2 Dual Fuel Engines
The CO emission factors for dual fuel engines were checked against information in
Table 4-2 of the EMF Document and was found to be in error. Table 4 presents the revised
emission factor. The rating remained a "D."
Table 4
Revised CO Emission Factor for Dual Fuel Engines
Engine
61
16
6
Engine Size
(hp)
711
2,410
8,658
Average
Revised CO Emission Factor
Ib/MMBtu
0.67
1.26
1.56
1.16
Ib/hp-hr
0.0044
0.0081
0.0099
0.0075
2.4 Sulfur Oxide. SO. and Carbon Dioxide. CO.
The SOX and CO2 emission factors remain as in the 5th Edition.
2.5 Particulate Matter. PM and PM Sizing
2.5.1 Total PM
The 5th Edition did not have PM emission factors for diesel or dual fuel engines.
Nineteen test reports were used to generate emission factors for diesel engines ranging in
size from 680 hp to 2,153 hp. Additionally, one data point in the existing 5th Edition was
combined with this data, making a total of 20 data points with ratings of "A" to "E". The
PM emission factor developed was 0.1 Ib/MMBtu (0.0007 Ib/hp-hr) with an overall rating of
"B." The data is presented in Table 5.
Table 5
PM Emission Factor Development for Diesel Engines
298-130-79-07/REPORTS/SEC 3-4.RVS
2-5
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Reference
3
2
5
15
6
7
13
4
8
12
10
19
18
1
14
11
16
9
17
Engine Size
(hp)
2,079
1,072
750
1,120
1,135
1,600
965
1,000
1,340
890
680
804
1,160
1,005
1,005
890
2,153
1,490
Unknown
AP-42 Fifth Ed.
Table 3. 4-5
Page 3. 4-7
Averages:
Standard Deviation
Number of Data Points
PM Total
(Ib/MMBtu)
1.2E-01
3.1E-02
1.1E-01
1.7E-01
1.5E-01
1.1E-01
1.1E-01
8.0E-02
7.1E-02
2.0E-01
1.1E-01
8.6E-02
2.8E-02
1.4E-01
1.3E-01
1.3E-01
1.3E-01
7.0E-02
5.0E-02
7.0E-02
l.OE-01
4.4E-02
20
PM Total
(Ib/hp-hr)
8.7E-04
2.2E-04
7.7E-04
1.2E-03
1.1E-03
7.7E-04
7.7E-04
5.6E-04
5.0E-04
1.4E-03
7.8E-04
6.0E-04
2.0E-04
9.7E-04
9.1E-04
9.0E-04
9.1E-04
5.1E-04
3.5E-04
4.9E-04
7.4E-04
3.1E-04
20
Data Rating
A
A
A
C
A
C
A
B
A
C
A
A
C
B
A
C
A
A
A
E
B
298-130-79-07/REPORTS/SEC 3-4.RVS
2-6
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2.5.2 PM Sizing
No changes were made to the PM Sizing emission factors.
2.6 Total Organic Carbon. TOC
The TOC emission factors were checked against information in Table 4-4 of the EMF
Document and remain the same as in the 5th Edition.
2.7 Speciated Organic and Poly cyclic Aromatic Compounds. PAH
These emission factors were checked against information in Table 4-5 of the EMF
document and no changes were made. However, due to some individual compounds being
below the detection limit (as indicated by "<"), the total PAH has been designated as "<."
2-7
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3.0 REFERENCES
1. Stamey-Hall, Susan, Evaluation of Nitrogen Oxide Emissions Data From TVA Coal-
Fired Boilers, EPA-600/R-92-242, U. S. Environmental Protection Agency, Research
Triangle Park, NC, December 1992.
2. Vatsky, J., and T. W. Sweeney, Development of an Ultra-Low NOX Pulverizer Coal
Burner, Presented at the EPA/EPRI 1991 Joint Symposium on Stationary Combustion
NOX Control, Washington, DC, March 25-28, 1991.
3. Lu, T. L., Lungren, R. L., and A. Kokkinos, Performance of a Large Cell-Burner
Utility Boiler Retrofit with Foster Wheeler Low-NOx Burners, Presented at the
EPA/EPRI 1991 Joint Symposium on Stationary Combustion NOx Control,
Washington, DC, March 25-28, 1991.
4. Alternative Control Techniques Document—NOx Emissions from Utility Boilers, EPA-
453/R-94-023, U. S. Environmental Protection Agency, Research Triangle Park, NC,
March 1994.
5. "Alternative Control Techniques Document~NOx Emissions From Utility Boilers,"
(1994) EPA-453/R-94-023, Office of Air Quality Standards, Research Triangle Park,
NC.
6. Steam: Its Generation and Use (1975) Babcock and Wilcox, New York.
7. Electric Utility Trace Substances Synthesis Report Volume 1: Synthesis Report. Electric
Power Research Institute, Palo Alto, California. November, 1994.
298-130-79-07/REPORTS/SEC 3-4.RVS
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4.0 REVISED SECTION 3.4
This section contains the revised Section 3.4.
298-130-79-07/REPORTS/SEC 3-4.RVS
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3-2
298-130-79-07/REPORTS/SEC3-4.RVS
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5.0 EMISSION FACTOR DOCUMENTATION, APRIL 1993
This section contains the Emission Factor Documentation for Section 3.4, dated
April, 1993.
5-1
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298-130-79-07/REPORTS/SEC 3-4.RVS
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EMISSION FACTOR DOCUMENTATION FOR
AP-42 SECTION 3.4,
LARGE STATIONARY DIESEL &
ALL STATIONARY DUAL FUEL ENGINES
Prepared by:
Acurex Environmental Corporation
Research Triangle Park, NC 27709
E.H. Pechan and Associates, Inc.
Rancho Cordova, CA 95742
EPA Contract No. 68-DO-0120
Work Assignment No. 11-68
EPA Work Assignment Officer: Michael Hamlin
Prepared for:
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
April 1993
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TABLE OF CONTENTS
Page
LIST OF FIGURES iv
LIST OF TABLES iv
CHAPTER 1. INTRODUCTION 1-1
CHAPTER 2. SOURCE DESCRIPTION 2-1
2.1 CHARACTERIZATION OF THE INDUSTRY 2-1
2.2 PROCESS DESCRIPTION 2-1
2.2.1 Fuel Type 2-2
2.2.2 Method of Ignition 2-2
2.2.3 Combustion Cycle 2-3
2.2.4 Charging Method 2-4
2.3 EMISSIONS 2-5
2.3.1 Nitrogen Oxides 2-6
2.3.2 Total Organic Compounds (Hydrocarbons) 2-9
2.3.3 Carbon Monoxide 2-9
2.3.4 Smoke, Particulate Matter, and PM-10 2-10
2.3.5 Sulfur Oxides 2-11
2.3.6 Carbon Dioxide 2-11
2.4 CONTROL TECHNOLOGIES 2-12
2.4.1 Engine Controls 2-12
2.4. .1 Combustion Cycle 2-12
2.4. .2 Injection Timing Retard 2-13
2.4. .3 Prelgnition Chamber Combustion - "Clean Burn"
Technology 2-13
2.4. .4 Air to Fuel Ratio 2-14
2.4. .5 Water Injection 2-15
2.4. .6 Derating 2-15
2.4.2 Post-Combustion Control 2-16
2.4.2.1 Selective Catalytic Reduction 2-16
2.4.2.2 Nonselective Catalytic Reduction 2-17
2.4.3 Control Technology Applications 2-18
REFERENCES 2-20
CHAPTER 3. EMISSION DATA REVIEW AND ANALYSIS PROCEDURES 3-1
3.1 LITERATURE SEARCH AND EVALUATION 3-1
REFERENCES 3-4
CHAPTER 4. EMISSION FACTOR DEVELOPMENT 4-1
4.1 CRITERIA POLLUTANTS AND CARBON DIOXIDE 4-2
4.1.1 Review of Previous Data 4-2
4.1.2 Review of New Data 4-3
4.1.3 Compilation of Baseline Emission Factors 4-4
4.1.4 Compilation of Controlled Emission Factors 4-4
4.2 TOTAL ORGANIC COMPOUNDS AND AIR TOXICS 4-4
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TABLE OF CONTENTS (Continued)
4.2.1 Review of Previous Data 4-4
4.2.2 Review of New Data 4-4
4.2.3 Compilation of Emission Factors 4-6
4.3 PARTICIPATE EMISSION AND SIZE DISTRIBUTION 4-6
4.3.1 Review of Previous Data 4-6
4.3.2 Review of New Data 4-6
4.3.3 Compilation of Emission Factors 4-7
REFERENCES 4-18
CHAPTER 5. AP-42 SECTION 3.4: LARGE STATIONARY DIESEL & ALL STATIONARY
DUAL FUEL ENGINES 5-1
APPENDIX A. SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE A-l
APPENDIX B. TRACE ELEMENT DATA B-l
APPENDIX C. FORMULAS AND ASSUMPTIONS USED TO CONVERT AND CALCULATE
EMISSION FACTORS C-l
APPENDIX D. MARKED-UP PREVIOUS AP-42 SECTION 3.4 D-l
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LIST OF FIGURES
FIGURE Page
Figure 1 Unweighted NOX and CO emissions versus engine ratings for diesel engines
greater than 600 hp 4-5
LIST OF TABLES
TABLE 3-3 EVALUATION OF REFERENCES 3-3
TABLE 4-la SUMMARY OF CRITERIA EMISSIONS DATA FOR DIESEL ENGINES 4-8
TABLE 4-lb SUMMARY OF CRITERIA AND CO2 EMISSIONS DATA FOR DIESEL
ENGINES 4-11
TABLE 4-2 SUMMARY OF CRITERIA EMISSIONS DATA FOR DUAL FUEL ENGINES 4-12
TABLE 4-3 NOX REDUCTION AND FUEL CONSUMPTION PENALTIES FOR DIESEL
AND DUAL FUEL ENGINES 4-12
TABLE 4-4 SUMMARY OF ORGANIC COMPOUND EMISSIONS DATA FOR DIESEL
AND DUAL FUEL ENGINES 4-13
TABLE 4-5 SUMMARY OF AIR TOXICS EMISSIONS DATA FOR A DIESEL ENGINE 4-15
TABLE 4-6 SUMMARY OF PARTICULATE EMISSIONS DATA FOR DIESEL ENGINES 4-17
IV
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1. INTRODUCTION
An emission factor is an estimate of the rate at which a pollutant (in terms of its
mass) is released to the atmosphere divided by the level of activity that is the source of the
emission (typically fuel consumption or energy output). Section 3.4 of the "Compilation of
Air Pollutant Emission Factors" (AP-42) covers the emission factors for large (greater than
600 hp) stationary diesel and all stationary dual fuel engines. The inclusion of all dual fuel
engines rather than only large dual fuel as was done previously is because there are few
applications and only sparse data for moderate- sized engines. This small population does
not warrant separate treatment elsewhere. Diesels, in contrast, have a large population
and distinct designs in the mid-capacity range and are treated in Chapter 3.3.
The emission factors provide persons working in air pollution control with
documented estimates of source emission rates. The emission factors, as stated in
"Technical Procedures for Developing AP-42 Emission Factors and Preparing AP-42
Sections," can be used in determining: (1) estimates of areawide emissions; (2) emission
estimates for a specific facility; and (3) evaluation of emissions in relation to ambient air
quality. The intent of this emission factor document is to provide background information
from all references used to support the revision of emission factors for Section 3.4 - Large
Stationary Diesel and Dual Fuel Engines. Chapter 2 contains information on the
combustion process used by large stationary diesel and all stationary dual fuel engines, as
well as emission characterization and controls. Chapter 3 summarizes the procedures and
data base available for this update and Chapter 4 presents the rationale for the changes
and additions to the emission factors. Chapter 5 contains the revision of AP-42 Chapter 3.4
completed as a result of the analysis presented in this report.
1-1
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The last update for Chapter 3.4 was in 1984. Previously, this Chapter contained
only emission factors for total particulate, nitrogen oxides (NOX), carbon monoxide (CO),
hydrocarbons (grouped as methane or nonmethane), and sulfur oxides (SOX). This revision
will include emission factors for those species as well as for carbon dioxide (CO2), total
organic compounds (TOCs) speciation and air toxics, and particulate sizing. The overall
scope of the current revision includes the following changes or additions:
! Updating of emissions factors for criteria pollutants during baseline,
uncontrolled, operation using data available since the prior supplement;
! Inclusion of several noncriteria emission species for which data are available:
organics speciation, air toxics, and greenhouse or ozone depletion gases (CO2);
and
! Inclusion of technical discussion and emissions data for engine operation with
NOX or CO control.
Section 3.4 deals with large compression ignition engines. In compression ignition
engines, the combustion air is compression heated in the cylinder before the diesel fuel oil is
injected into the cylinder to produce spontaneous combustion. Spontaneous ignition occurs
because the air is above the automatic ignition temperature of the fuel. The resulting high
pressure products of combustion pushes the piston through the cylinder and is then
converted from linear to rotary motion by a crankshaft. All diesel fueled engines are
compression ignited. Although all natural gas fueled engines are spark ignited (spark of an
electrical discharge initiates combustion), natural gas can be used in a compression ignition
engine if a small amount of diesel fuel is injected into the compressed natural gas-air
mixture in the cylinder to initiate combustion. Hence, the use of diesel with natural gas to
fuel an engine is termed "dual fueled."
1-2
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2. SOURCE DESCRIPTION
2.1 CHARACTERIZATION OF THE INDUSTRY
Stationary reciprocating internal combustion (1C) engines are used in a variety of
applications where there is a requirement for mechanical work which can be derived from
the power generated by a shaft. Installations range from within large urban centers to
remote areas. Large engines can be found operating in a variety of applications such as
electric power generation for both base and standby service, oil and gas pipeline
pumping/transport, oil and gas exploration and production, irrigation, hoisting, and
nuclear power plant emergency cooling water pump operation.
Compression ignition engines can operate at a higher compression ratio (ratio of
cylinder volume when the piston is at the bottom of its stroke to the volume when it is at the
top of its stroke) than spark ignited engines because fuel is not present during compression;
thus, there is no danger of premature automatic ignition. Since the thermal efficiency of an
engine increases with increasing pressure ratio (and pressure ratio varies directly with
compression ratio), compression ignited engines are more efficient than spark ignited
engines. This increased efficiency is gained at the expense of poorer acceleration (response
to load changes) and a heavier structure to withstand the higher pressures.12
2.2 PROCESS DESCRIPTION1
All reciprocating internal combustion engines operate by the same basic process. A
combustible mixture is first compressed in a small volume between the head of a piston and
its surrounding cylinder. The mixture is then ignited, and the resulting high pressure
products of combustion push the piston through the cylinder. This movement is converted
from linear to rotary motion by a crankshaft. The piston returns, pushing out exhaust
gases, and the cycle is repeated. Although all reciprocating 1C engines follow the same
2-1
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basic process, there are variations that classify engine types. Engines are generally
classified by their: fuel burned, method of ignition, combustion cycle, and charging
method.
2.2.1 Fuel Type
The three primary fuels for stationary reciprocating internal combustion engines
are gasoline, diesel (No. 2) oil, and natural gas. Gasoline is used primarily for mobile and
portable engines. Construction sites, farms, and households typically use converted mobile
engines for stationary application because their cost is often less than an engine designed
specifically for stationary purposes. In addition, mobile engine parts and service are
readily available, and gasoline is easily transported to the site. Thus, gasoline is an
essential fuel for small and medium size stationary engines.
Diesel fuel oil is also easily transported, and therefore is used in small and medium
size engines. Also, the generally higher efficiencies exhibited by diesel engines makes diesel
oil an ideal fuel for large engines where operating costs must be minimized. Diesel is thus
the most versatile fuel for stationary reciprocating engines.
Natural gas is used more than any other fuel for large stationary reciprocating or
turbine 1C engines, typically operating pumps or compressors on gas pipelines.
Other fuels are also burned in stationary 1C engines, but their use is limited. Some
engines burn heavy fuel oils, and a few burn almost any other liquid fuel. Gaseous fuels
such as sewer gas are sometimes used at wastewater treatment plants where the gas is
available. Stationary 1C engines can be modified to burn almost any liquid or gaseous fuel
if the engine is properly designed and adjusted.
2.2.2 Method of Ignition
Ignition is the means of initiating combustion in the engine cycle. There are two
methods used for stationary reciprocating 1C engines: compression ignition (CI) and spark
ignition (SI).
In compression ignition engines, combustion air is first compression heated in the
cylinder, and diesel fuel oil is then injected into the hot air. Ignition is spontaneous as the
air is above the automatic ignition temperature of the fuel. Spark ignition engines initiate
2-2
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combustion by the spark of an electrical discharge. 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 burn any mixture ratio of gas and diesel oil, from 6 to 100
percent oil (based on heating value).
2.2.3 Combustion Cycle
The combustion process for stationary reciprocating internal combustion engines
consists of compressing a combustible mixture by a piston, igniting it, and allowing the
high pressures generated to push the piston back. This process may be accomplished in
either four strokes or two strokes of the piston.
In the four-stroke cycle, the sequence of events is summarized as follows:
! Intake stroke — suction of the air or air and fuel mixture into the cylinder by the
downward motion of the piston through the cylinder;
! Compression stroke — compression of the air or air and fuel mixture, thereby
raising its temperature and reducing its volume;
! Ignition and power (expansion) stroke ~ combustion and consequent downward
movement of the piston by pressure from the expanding gases with energy
transfer to the crankshaft; and
! Exhaust stroke ~ expulsion of the exhaust gases from the cylinder by the upward
movement of the piston.
A two-stroke cycle completes the power cycle in one revolution of the crankshaft as
compared to two revolutions for the four-stroke cycle. 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 through the cylinder. 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
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ports are covered (and/or valves closed), and the fresh charge of air or air and fuel is again
compressed for the next cycle.
Two-stroke engines have the advantage of higher horsepower to weight ratio
compared to four-stroke engines when both operate at the same speed. In addition, if ports
are used instead of valves, the mechanical design of the engine is simplified. However,
combustion can be better controlled in a four-stroke engine and excess air is not needed to
purge the cylinder. Therefore, four-stroke engines tend to be slightly more efficient, and
typically emit less pollutants (primarily unburned hydrocarbons) than two-stroke engines.
2.2.4 Charging Method
Charging is the method of introducing air or the air and fuel mixture into the
cylinder. Three methods are commonly used: natural aspiration, turbocharging, and
blower scavenged.
A naturally aspirated engine uses the vacuum created behind the moving piston
during the intake stroke to suck in the fresh air charge. This process tends to be somewhat
inefficient, however, since the actual amount of air drawn into the cylinder is only about 50
to 75 percent of the displaced volume. A more efficient method of charging is to pressurize
the air (or air and fuel) and force it into the 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 increases the power density, or power output per
unit weight (or volume) of the engine, since more air mass can be introduced into the
cylinder. As air pressure increases, its temperature also rises because of the action of the
compressor on the air. Therefore, the pressurized air is often cooled before entering the
cylinder to further increase power by allowing more air mass to be introduced into the
cylinder. This process is called intercooling or aftercooling.
Two-stroke engines are often air charged by a blower, which also aids in purging
the exhaust gases. Such systems are called blower-scavenged. This method is less efficient
than turbocharging because the blower produces less pressure than a turbine. However,
high volumetric flow rates are achieved, effectively purging the cylinder of exhaust gases.
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In a CI engine, fuel is injected into the cylinder near the end of the compression
stroke; whereas, in a SI engine, the fuel is usually added to the air downstream of the
turbocharger if any is used, and before the mixture enters the cylinder. This is done with a
carburetor. However, some SI engines (particularly large natural gas fueled engines) inject
the fuel into the intake manifold just ahead of the valves, or into the cylinder as done with
CI engines.
Two methods of injection are commonly used. Direct injection places the fuel
directly into the cylinder and the principal combustion chamber. These units are also
called open chamber engines because combustion takes place in the open volume between
the top of the piston and the cylinder. In contrast is indirect injection, where combustion
begins in a fuel rich (oxygen deficient) atmosphere in a 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.
2.3 EMISSIONS
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 that 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 (CI) engines enter the atmosphere from the exhaust. Crankcase blowby is minor
because hydrocarbons are not present during compression of the charge. Evaporative
losses are insignificant in diesel engines because of the low volatility of diesel fuels. In
general, evaporative losses are also negligible in engines using gaseous fuels because these
engines receive their fuel continuously from a pipe rather than via a fuel storage tank and
fuel pump. In gasoline-fueled engines, 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. However, crankcase blowby
emissions can be virtually eliminated through the simple expedient use of the positive
crankcase ventilation (PCV) valve. Other fugitive emissions may result from diesel fuel
storage.
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The primary pollutants from internal combustion engines are NOX, hydrocarbons
and other organic compounds (HC), CO, and particulates, which include both visible
(smoke) and nonvisible emissions. Nitrogen oxide 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. Ash and metallic additives in the fuel also contribute to the particulate
content of the exhaust. Oxides of sulfur also appear in the exhaust from 1C engines. The
sulfur compounds, mainly sulfur dioxide (SO2), are directly related to the sulfur content of
the fuel.2
2.3.1 Nitrogen Oxides
Nitrogen oxide formation occurs by two fundamentally different mechanisms. The
principal mechanism with engines is thermal NOX, which arises from the thermal
dissociation and subsequent reaction of nitrogen (N2) and oxygen (O2) molecules in the
combustion air. Most thermal NOX is formed in the highest temperature region of the
flame after most hydrocarbon oxidation has occurred. A component of thermal NOX, called
prompt NOX, is formed from early reactions of nitrogen intermediaries and hydrocarbon
radicals from the fuel. The second mechanism, fuel NOX, stems from the evolution and
reaction of fuel-bound nitrogen compounds with oxygen. Natural gas has negligible
chemically bound fuel nitrogen (although some molecular nitrogen) and essentially all NOX
formed is thermal NOX. Distillate oils have small levels of bound nitrogen. These levels are
usually significant only for high degrees of NOX controls where thermal NOX has been
suppressed to the level where fuel NOX is significant. Residual oils contain fuel bound
nitrogen; upon combustion, NOX is formed by all mechanisms. Some large bore diesels fire
residual oil, but the NOX potential is usually a deterrent to this fuel. The formation of
prompt NOX is significant only in very fuel-rich flames and is not of major importance for
reciprocating 1C engines.
At high temperatures (thermal NOX), both N2 and O2 molecules in the combustion
air absorb the heat energy up to the point where they are dissociated into their respective
atomic states, N and O. The subsequent reaction of these atoms to create thermal NOX is
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described by the Zeldovich mechanism:
N2 + O - NO + N
N + O2 - NO + O
The rates of these reactions are highly dependent upon the stoichiometric ratio, combustion
temperature, and residence time at the combustion temperature.
The maximum thermal NOX production occurs at a slightly lean fuel mixture ratio
because of the excess availability of oxygen for reaction. The control of stoichiometry is
critical in achieving reductions in thermal NOX. The thermal NOX generation decreases
rapidly as the temperature drops below the adiabatic temperature (for a given
stoichiometry). Thus, maximum reduction of thermal NOX generation can be achieved by
control of both the combustion temperature and the stoichiometry.
In fuel NOX, the nitrogen compounds (primarily organic) contained in the fuels are
evolved and react to form NOX. The degree of oxidation of the nitrogen in the fuel is
strongly dependent upon the stoichiometric ratio and fuel nitrogen concentration; and
weakly dependent upon the flame temperature and the nature of the organic nitrogen
compound. It is the weak influence of temperature on gas-phase NOX conversion that
reduces the effectiveness of NOX controls which rely on temperature effects in the
combustion of nitrogen-bearing fuels. Here, as with thermal NOX, controlling excess O2
(stoichiometry) is an important part of controlling NOX formation.
The majority of NOX formed is thermal NOX because of the high flame temperatures
and pressures of 1C engines. As diesel fuel and natural gas are the predominate fuels for
this source, little fuel NOX is formed, except in engines that fire residual and/or crude oils.
When fuel is injected into the cylinder, it undergoes a series of reactions that lead to
ignition. The time between the start of injection of the fuel and the start of combustion (as
measured by the onset of energy release) is called the ignition delay. Initial combustion
occurs around the periphery of the fuel jet, where the air/fuel ratio is close to the
stoichiometric ratio.
During ignition delay, some of the fuel is pre-mixed with air and evaporates. After
ignition occurs, the premixed charge burns extremely rapidly, thereby quickly releasing
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energy. Most of the burning takes place as a diffusion flame after the premixed charge has
burned.
Nitrogen oxide emissions are directly affected by the amount of premixing which, in
turn, is a function of ignition delay. When ignition delay is large, there is more premixing
and a greater energy release rate at the start of combustion. This generally leads to higher
temperatures and, accordingly, higher NOX emissions.
In general, engine load does not have a profound effect on the brake-specific (NOX
rate to power output ratio) NOX emission rates for diesel-fueled engines, although the total
mass emission rates increase as the engine load increases. At very low engine loads, almost
all of the energy is released during the premixed stage. Consequently, brake-specific
emissions under these conditions are relatively high. As load increases, the amount of
premixed burning remains relatively constant while the amount of diffusion burning
increases linearly. The amount of NOX produced during this stage is proportional to the
amount of fuel consumed because most of the diffusion burning takes place at
stoichiometric conditions. Thus, as engine load increases, the concentration of NOX in the
exhaust gas increases. However, the brake-specific NOX emission rate remains roughly the
same since power output also increases by the same factor.
Brake-specific NOX emission rates for dual-fuel compression ignition engines are
sensitive to load. Emission rates are greatest at high loads. Dual-fuel engines generally
burn a homogeneous charge of fuel. A compression ignition engine is unthrottled; the
air/fuel ratio of the charge decreases as engine load increases. At high loads, combustion
occurs closer to the point where maximum NOX is produced.
Preignition chamber engines have lower baseline NOX emissions that direct fuel
injection engines. Shorter ignition delay combined with the generally richer combustion
conditions in the preignition chamber results in smoother combustion and lower peak
temperatures. In addition, there are significant heat transfer losses as the combustion gas
goes from the pre-ignition chamber to the main combustion chamber, lowering peak
temperatures.3
2.3.2 Total Organic Compounds (Hydrocarbons)
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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
cylinder walls causes the mixture temperatures to be too low to support combustion.
Partially burned hydrocarbons can occur for a number of reasons:
! Poor air and fuel homogeneity due to incomplete mixing prior to, or during,
combustion;
! Incorrect air/fuel ratios in the cylinder during combustion due to maladjustment
of the engine fuel system;
! Excessively large fuel droplets (diesel engines); and
! 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.
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.2
2.3.3 Carbon Monoxide
Carbon monoxide is a colorless, odorless, relatively inert gas formed as an
intermediate combustion product that appears in the exhaust when the reaction of CO to
CO2 cannot proceed to completion. This situation occurs if there is a lack of available
oxygen near the hydrocarbon (fuel) molecule during combustion, if the gas temperature is
too low, or if the residence time in the cylinder is too short. 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 and fuel mixing during the combustion process.
2.3.4 Smoke. Particulate Matter, and PM-10
White, blue, and black smoke may be emitted from 1C engines. Liquid particulates
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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
temperature is not high enough to ignite the fuel. They consist primarily of raw fuel with
some partially burned hydrocarbons and lubricating oil. 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 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. Proper maintenance is the most effective
method of preventing these emissions from all types of 1C engines.
The primary constituent of black smoke is agglomerated carbon particles (soot).
These form in a two-step process in regions of the combustion mixture that are oxygen
deficient. 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/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. The formation of particles 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 CO2 if it is still
at an elevated temperature. Since the temperature of the exhaust system is too low for this
oxidation to occur, soot exiting the combustion chamber before it has had the opportunity
to oxidize completely will be discharged as visible particles.
Because soot formation is very sensitive to the need for oxygen, its discharge is
greatest when the engine is operating at rich air/fuel ratios, such as at rated power and
speed. Therefore, naturally aspirated engines are likely to have higher smoke levels than
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turbocharged engines, which operate at leaner air/fuel ratios.2
PM-10 is the name applied to the smaller sized particles in the air (less than 10
micrometers in aerodynamic diameter). Exposure to PM-10 can result in both short and
long term reductions in lung function because the particles are too small to be trapped by
the nose and large enough that some deposition in the lungs occurs.
PM-10 is the pollutant that causes most of the air-pollution-induced reduction in visibility.4
2.3.5 Sulfur Oxides
Sulfur oxide emissions are a function of the sulfur content in the fuel, only, rather
than of any combustion variables. In fact, during the combustion process essentially all the
sulfur in the fuel is oxidized to SO2. The oxidation of SO2 gives sulfur trioxide (SO3), which
reacts with water to give sulfuric acid (H2SO4), a contributor to acid precipitation. Sulfuric
acid reacts with basic substances to give sulfates, which are fine particulates that
contribute to PM-10 and visibility reduction. The reduction of SOX emissions would also
minimize corrosion of the engine parts.2'4
2.3.6 Carbon Dioxide
Concern about the increasing release of greenhouse gases such as CO2 has grown
out of research that documents the buildup of gases in the atmosphere and estimates the
implications of continued accumulations. Carbon dioxide is largely transparent to
incoming solar radiation, but can absorb infrared radiation reemitted by the Earth.
Because of this energy "trapping" property, such a gas is referred to as a greenhouse gas.
The warming of the surface of the Earth and cooling of the stratosphere is achieved via
molecular absorption and reradiation in the infrared spectrum. The Earth reemits the
energy it absorbs back to space, thus maintaining an energy balance. Because the Earth is
much colder than the Sun, the bulk of the Earth's emission takes place at longer
wavelengths than those of incoming solar radiation. Although CO2 is a relatively inefficient
absorber of solar radiation, it is a strong absorber of longwave (infrared) radiation.
Although some of the reemitted energy reaches space, some of the radiation is transmitted
downward, leading to a net trapping of longwave radiation and a warming of the surface.5
2.4 CONTROL TECHNOLOGIES
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The majority of control development and installation for large reciprocating engines
has been for NOX control. The implementation of control has occurred in a few isolated
geographical areas, since there is no federal New Source Performance Standard (NSPS).
Most control techniques have attempted to modify the combustion process to suppress NOX
formation. In stringent cases, post combustion control by catalytic or noncatalytic
reduction has been partially developed, but installed in only rare cases due to cost and the
previous lack of need for such levels of reduction. Some stationary engines are starting to
be retrofitted with catalytic CO or volatile organic compound (VOC) control. There is
insufficient information on CO and VOC add-on controls to formulate emission factors at
this time.
2.4.1 Engine Controls1'46
2.4.1.1 Combustion Cycle. Reciprocating 1C engines may be either two- or four-
stroke cycle. During combustion, emissions from either type are essentially identical.
However, during the charging of a two-cycle engine, several events take place. On
noninjected engines, the scavenging air, which purges the cylinder of exhaust gases and
provides the combustion air, can also sweep out part of the fuel charge. Thus, carbureted
two-cycle engines often have higher organic compound emissions in the form of unburned
fuel than fuel injected engines.
The two-stoke engine can also have lower NOX emissions than the four-stroke
engine. If the cylinder is not completely purged of exhaust gases, the result is internal
exhaust gas recirculation (EGR). The remaining inert exhaust gases absorb energy from
combustion, lowering peak temperatures, and thereby lowering NOX. Internal EGR can
reduce NOX emissions from 4 to 37 percent. External EGR (turbocharged models) can have
reductions varying from 25 to 34 percent. These reductions were obtained with exhaust
gas recirculation rates of 6.5 to 12 percent. At 6 percent EGR, NOX reductions ranged from
10 to 22 percent. In general, fuel consumption remained unchanged for EGR rates less
than 12 percent.
2.4.1.2 Injection Timing Retard. Ignition in a normally adjusted 1C engine is set to
occur shortly before the piston reaches its uppermost position [top dead center, (TDC)].
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At TDC, the air or air and fuel mixture is at maximum compression. 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.
Retarding the timing beyond TDC, the point of optimum power and fuel
consumption, reduces the rate of NOX production. Retarding causes more of the
combustion to occur later in the cycle, during the expansion stroke, thus lowering peak
temperatures, pressures, and residence times. The efficiency loss is identifiable by the
increase in fuel flow needed to maintain rated power output. This practice carries with it a
fuel consumption penalty of 5 to 8 percent and the potential of excessive smoke. Typical
retard values range from 2° to 6° depending on the engine. Beyond these levels, fuel
consumption increases rapidly, power drops, and misfiring occurs. Also, TOC, CO, and
visible emissions increase, and elevated exhaust temperatures shorten exhaust valves and
turbocharger service lives. Increasing the fuel injection rate has been used on some diesel
systems to partially mitigate the CO and TOC emissions and fuel consumption effects of
retarded injection timing. A high injection rate, however, results in increased mixing of air
and fuel and a subsequently hotter flame at the initiation of combustion. There is,
therefore, a NOX trade-off with this modification. Injection timing retard is an applicable
control with all 1C engine fuels.
The reported level of control is in the range of 0.6 to 8.5 percent reduction for each
degree of retard. On the average, diesel engines reduce NOX by 25 percent for 4° of retard
and 40 percent for 8° of retard. Fuel usage increases approximately 2 percent at 4° retard,
whereas 8° of retard raises fuel usage by about 6 percent.
2.4.1.3 Pre-Ignition Chamber Combustion - "Clean Burn" Technology. The use of
a preignition chamber can improve fuel efficiency and reduce NOX emissions. The system
is designed to burn lean air/fuel mixtures. The fuel charge is introduced into the pre-
chamber as a rich mixture and ignited by a spark-plug. Since it burns in the absence of
excess oxygen, NOX formation is inhibited. This "torch" of burning fuel expands into the
power cylinder where it thoroughly ignites a lean mixture at reduced temperatures.
Therefore, combustion is completed in an overall lean mixture at temperatures that are
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adequate for combustion but below those where NOX formation occurs. This NOX control is
currently applied to natural gas-fired engines only.
2.4.1.4 Air to Fuel Ratio. In injection type engines, which include all diesel and
many dual fuel and gas varieties, the air/fuel ratio for each cylinder can be adjusted by
controlling the amount of fuel that enters each cylinder. These engines are therefore
operated lean where combustion is most efficient and fuel consumption is optimum.
At air/fuel ratios below stoichiometric (rich), combustion occurs under conditions of
insufficient oxygen and thus unburned hydrocarbon emission increase. Carbon monoxide
increases because carbon is not sufficiently oxidized to CO2. Nitrogen oxides decrease both
because of insufficient oxygen and lower temperatures.
At air/fuel ratios above stoichiometric (lean), combustion occurs under conditions of
excess oxygen, thus essentially all carbon is oxidized to CO2. Nitrogen oxides first increase
rapidly with the air/fuel ratio near stoichiometric, because of the excess oxygen and peak
temperatures, then decreases rapidly with increasing air/fuel ratio as the excess air cools
peak combustion temperatures. Hydrocarbons stay at a low level, then begin to increase as
the air/fuel ratio is increased because the lower temperatures inhibit combustion.
The choice of lean or rich operation often depends on engine use. Rich operating
(meaning close to stoichiometry) engines give quicker response to changing
conditions/loads, and also produce maximum power. The most practical use of air/fuel
ratio adjustment as a control technique is to change the setting toward leaner operation.
The oxygen availability will increase but so will the capability of the air and combustion
products to absorb heat. Consequently, the peak temperature will fall, resulting in lower
NOX formation rates. The limiting factor for lean operation is the increased emissions of
hydrocarbons at the lower temperatures. Small changes in the air/fuel ratio,
approximately 10 percent, can reduce NOX by about 30 percent with a fuel penalty of about
5 percent.
Charging method is important because it often limits the range of the air/fuel ratio
(A/F). Naturally aspirated carbureted engines generally must operate with overall air/fuel
equivalence ratios, defined as {(A/F)stoichiometric}/{(A/F)actua|}, greater than 0.7 because poor
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distribution among cylinders will allow some cylinders to go excessively lean. In contrast,
turbocharged fuel injected engines, with precise control of air/fuel ratio to each cylinder,
can operate at equivalence ratios of 0.5 to 0.3 without increasing hydrocarbon emissions
significantly. Some blower-scavenged engines operate at equivalence ratios below 0.25,
although the actual ratio inside the cylinder is usually higher.
2.4.1.5 Water Injection. As with combustion turbines, water or steam injection can
reduce NOX emissions from 1C engines. Water injection reduces NOX emissions but usually
increases HC emissions because of the lower peak temperatures achieved. Carbon
monoxide appears to be unaffected by water injection. Wet control effectiveness correlates
inversely with excess air levels. Since wet controls reduce peak temperature by increasing
the charge mass and absorbing the latent heat of vaporization, the technique is more
effective in a low excess air system than in one with much excess air. The lower thermal
mass with low excess air will experience a greater temperature drop. Systems with high
excess air absorb all the heat that can be transferred to a fluid in the short time between
combustion and peak temperature. The application of this control to 1C engines has been
limited due to inaccessibility of water injection. A more plausible application of wet
controls may be in the use of water-fuel emulsions.
2.4.1.6 Derating. An engine can be derated by restricting its operation to lower
levels of power production than normal for the given application. Derating reduces
cylinder pressures and temperatures and thus lowers 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., g/hp-hr) are not reduced. This is especially true for four-stroke
turbocharged engines. In addition, air/fuel ratios change less with derating for
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 can result in higher CO and HC emissions.
One significant disadvantage of derating is that spare engine capacity may be
needed which could require a large capital investment. For new engines, derating can be
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applied by designing the engine to operate under derated conditions. This could mean a
larger, more expensive engine to do the same job.
2.4.2 Post-Combustion Control2 78
2.4.2.1 Selective Catalytic Reduction. In the selective catalytic reduction (SCR)
process, anhydrous ammonia (NH3) gas, usually diluted with air or steam, is injected
through a grid system into the exhaust gas stream upstream of a catalyst bed. On the
catalyst surface, the NH3 reacts with NOX to form molecular nitrogen and water.
Depending on system design, NOX removal of 80 to 90 percent and higher is achievable.
The global reactions that occur in the presence of the catalyst are as follows:
4NH3 + 4NO + O2 - 4N2 + 6H2O
4NH3 + 2NO2 + O2 - 3N2 + 6H2O
The reaction of NH3 and NOX is favored by the presence of excess oxygen (fuel-lean
conditions). The primary variable affecting NOX reduction is temperature. Optimum NOX
reduction occurs at catalyst bed temperatures between 600 and 750 °F for conventional
(vanadium or titanium-based) catalyst types, and 470 to 510 °F for platinum catalysts.
Performance for a given catalyst depends largely on the temperature of the exhaust gas
being treated. A given catalyst exhibits optimum performance between a temperature
range of approximately +/- 50 °F for applications where flue gas O2 concentrations are
greater than 1 percent. Below this optimum temperature range, the catalyst activity is
greatly reduced, allowing unreacted ammonia to slip through. Above 850 °F, ammonia
begins to be oxidized to form additional NOX. The ammonia oxidation to NOX increases
with increasing temperature. Depending on the catalyst substrate material, the catalyst
may be quickly damaged due to thermal stress at temperatures in excess of 850 °F. It is
important, therefore, to have stable operations and uniform flue gas temperatures for this
process to achieve optimum NOX control.
The optimal effectiveness of the catalytic process is also dependent on the NO3/NOX
ratio. Ammonia injection rates must be controlled to give an optimum NH3/NOX mole ratio
of about 1:1. As the mole ratio of NH3/NOX increases to approximately 1:1, the NOX
reduction increases. Operating with ammonia injection above this level with insufficient
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catalyst volume will result in unreacted ammonia slipping through the catalyst bed. On-
stream analyzers and quick feedback control are required to optimize the NOX removal and
minimize NH3 emissions.
Another variable that affects NOX reduction is space velocity, the ratio of flue gas
flow rate to catalyst volume, or the inverse of residence time. For a given catalyst volume,
increased flue gas rate decreases the conversion NOX. Conversely, for a given flue gas flow
rate, increased catalyst volume improves the NOX removal effectiveness.
Site-specific factors including operating temperatures and fuel type affect the
performance and emission rates achievable with SCR. There are a number of operating
considerations with SCR. First, potential catalyst poisoning by either metals, acid gases, or
particulate entrainment is detrimental. The potential loss of catalyst activity due to these
fuel effects results in the use of an excess of catalyst to maintain the required process
efficiency over an extended period of time. Second, NH3 emissions result. In a properly
designed and controlled system, NH3 emissions should be less than 10 ppm. A major issue
results when flue gas temperatures are outside the proper catalyst operating range. This
problem can be aggravated by load changes. The correction may require retrofit of reheat
heat exchange hardware. An increase in back pressure due to pressure drop across the
catalyst results in a decrease to fuel efficiency. In addition, the formation of ammonium
sulfate and bisulfate in the presence of SO3 and unreacted ammonia presents corrosion and
plugging concerns.
2.4.2.2 Nonselective Catalytic Reduction. Nonselective catalytic reduction (NSCR)
systems are often referred to as three-way conversion catalyst systems since they reduce
NOX, unburned hydrocarbon, and CO simultaneously. To operate properly, the
combustion process must occur with an air/fuel ratio slightly fuel-rich of stoichiometric.
Under this condition, in the presence of the catalyst, the oxides of nitrogen are reduced by
the CO, resulting in nitrogen and CO2. Sulfur resistant catalysts supports of titanium,
molybdenum or tungsten are available for SO3-laden stream applications. Deposits are
controlled by control of NH3 slip to below 5 ppmv.
Nonselective catalytic reduction systems primarily utilize the following reaction in
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reducing NOX:
2CO + 2NOX - 2CO2 + N2
The catalyst used to promote this reaction is generally a mixture of platinum and rhodium.
The catalyst operating temperature limits are 700 to 1,500 °F, with 800 to 1,200 °F being
the most desirable. Temperatures above 1,500 °F result in catalyst sintering.
Typical NOX conversion ranges from 80 to 95 percent with corresponding decreases
in CO and HC. Potential problems associated with NSCR applications include catalyst
poisoning by oil additives (e.g., phosphorous, zinc) and inadequate control systems.
Nonselective catalytic reduction is limited in application to 1C engines with fuel-rich
ignition systems.
2.4.3 Control Technology Applications
From an NOX control viewpoint, the most important distinction among engine
models and types for reciprocating engines is rich-burn versus lean-burn. Exhaust from
rich-burn engines has little or no excess air while the exhaust form lean burn engines is
characterized with medium to high levels of O2.
For natural gas/dual fuel engines, engine design in general and clean burn or pre-
ignition chamber combustion have been the most commonly applied engine control
technology for NOX reduction in the past decade. In diesel oil fueled engines, the most
common engine control techniques employed include injection timing retard and clean
burn.
Selective catalytic reduction technology has been applied to lean-burn reciprocating,
diesel, and dual fueled engines where the exhaust gas O2 concentrations are high as the
SCR reaction mechanisms require presence of oxygen. Application of NSCR requires fuel-
rich engine operation or the addition of reducing agents in the flue gas upstream of the
catalyst. Therefore, application of this technology has been limited to rich-burn engines.
The Manufacturers of Emission Controls Association (MECA), states that catalytic
oxidation controls for CO emissions are achieving 90 to 99 percent in commercial
applications. For NOX control, SCR technology on lean-burn engines has achieved 90 to 95
percent control efficiency in limited applications. Nonselective catalytic reduction on rich-
2-18
-------
burn engines has reached 90 to 99 percent control efficiency levels with more extensive
experience, particularly in California. There is also commercial availability of VOC
controls for diesel, lean-burn, and rich-burn 1C engines, but with very little operating
experience to data.
Several commercial processes currently exist to remove carbon dioxide. However,
currently, there is no regulatory or economic incentive for utilities or private industry to
remove carbon dioxide, and large-scale carbon dioxide removal and disposal processes are
very expensive.9
2-19
-------
\
20
f-\
|
^ 13
O
tn
o
w 10
UJ
Q
LJJ
1 S
—
%
r>
0
x x
X X
x x
X
xx x
X
x x x
X
X
X
0 o 0
o
° ° 00° 0
1 O . ' . I . — 2l . 1 " ! 1 —
N3X
X
CO
X
'
•t,nan 2,000 s.oaa 4,000 s.aoa
ENGINE HATING
6,000 7,000 B, 000
Figure 4-1. Unweighted NOX and CO emissions versus engine ratings for diese!
engines greater than 600 hp.
4-5
2-20
-------
REFERENCES FOR CHAPTER 2
1. Technical Procedures for Developing AP-42 Emission Factors and Preparing AP-42
Sections, (Draft), Emission Inventory Branch, Technical Support Division, Office of
Air and Radiation, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, March 6,1992.
2. Standards Support and Environmental Impact Statement, Volume I: Stationary
Internal Combustion Engines, EPA-450/2-78-125a, Emission Standards and
Engineering Division, Office of Air, Noise, and Radiation, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, NC, July 1979.
3. Campbell, L.M., D.K. Stone, and G.S. Shareef, "Sourcebook: NOX Control
Technology Data," EPA-600/2-91-029, Radian for Control Technology Center,
Emission Standards Division, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, July 1991.
4. Hoggan, M., S. Cohanim, R. Sin, M. Hsu, and S. Tom, "Air Quality Trends in
California's South Coast and Southeast Desert Air Basins, 1976-1990, Air Quality
Management Plan, Appendix II-B," South Coast Air Quality Management District,
July 1991.
5. "Limiting Net Greenhouse Gas Emissions in the United States, Volume II: Energy
Responses," DOE/PE-0101 Vol. II, Report for the Office of Environmental Analysis,
Office of Policy, Planning and Analysis, Department of Energy, September 1991.
6. Castaldini, C., "Environmental Assessment of NOX Control on a Compression
Ignition Large Bore Reciprocating Internal Combustion Engine, Volume I:
Technical Results," EPA-600/7-86/001a, prepared by Acurex Corporation for the
Combustion Research Branch of the Energy Assessment and Control Division,
Industrial Environmental Research Laboratory, Office of Research and
Development, U.S. Environmental Protection Agency, Washington, DC, April 1984.
7. Catalysts for Air Pollution Control, brochure by the Manufacturers of Emission
Controls Association (MECA), Washington, DC, March 1992.
8. Castaldini, C., and L.R. Waterland, "Environmental Assessment of a Reciprocating
Engine Retrofitted with Selective Catalytic Reduction, Volume I: Technical
Results," EPA/600/7-86/014a, by Acurex Corporation for Air and Energy
Engineering Research Laboratories, Office of Research and Development, U.S.
Environmental Protection Agency, December 1984.
2-21
-------
REFERENCES FOR CHAPTER 2 (Continued)
9. "Limiting Net Greenhouse Gas Emissions in the United States, Volume I: Energy
Technologies," DOE/PE-0101 Vol. I, Report for the Office of Environmental
Analysis, Office of Policy, Planning and Analysis, Department of Energy, September
1991.
2-22
-------
3. EMISSION DATA REVIEW AND ANALYSIS PROCEDURES
This section reviews the literature search and evaluation procedures used to obtain
and review documents (or other sources of information). It also presents data found
among the sources, the data quality (indicating the level of confidence of the data in terms
of method used to sample and reporting of results), and the guideline tables used to
determine the data quality. All emissions data were reviewed and analyzed based on EPA
guidelines which define criteria for rating both emissions test data and overall emission
factors that were adopted in this update.1 The criteria for rating individual emissions data
were as follows:
A - When tests are performed by a sound methodology and are reported in enough
detail for adequate validation. These tests are not necessarily EPA reference
method tests, although such reference methods are preferred and certainly to
be used as a guide.
B - When tests are performed by a generally sound methodology, but they lack
enough detail for adequate validation.
C - When tests are based on an untested or new methodology or are lacking a
significant amount of background data.
D - When tests are based on a generally unacceptable method, but the method may
provide an order-of-magnitude value for the source, or no background data is
provided at all.
The criteria for ranking emission factors are discussed in Chapter 4.
3.1 LITERATURE SEARCH AND EVALUATION
Several different approaches were followed to obtain literature/data to help update
3-1
-------
the emission factors. The applicable references and sources listed in Table 3-1 were
obtained and reviewed along with documents found through a "Dialogue" computer
abstract search, an in-house data search, an EPA library search, an Electric Power
Research Institute (EPRI) library search, periodicals, and extensive contacts with trade
organizations, manufacturers, local, state, and federal air quality agencies. The references
used and reviewed for this update are shown as References 2 through 14 at the end of this
chapter.
A number of contacts were active when the emission factor documentation for this
current update was produced. It is expected that some of these will produce new data after
the current update is concluded. In particular, a letter was submitted to the Engine
Manufacturers Association (EMA). Their responses to the request for information are in
process. A complete list of contacts made can be found in Appendix B.
After reviewing all information provided by the sources, the data were initially
evaluated according to EPA guidelines. A tabular rating checklist was used for each
reference to determine whether or not data were presented in enough detail to be useful.
These tables, presented in Chapter 4, also helped determine the data quality.
3-2
-------
TABLE 3-1. EVALUATION OF REFERENCES
Reference
2
3
4
5
6
7
8
9
10
11
12
13
14
Used in AP-42
revision
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
No
Why/Why Not
Used in previous revision/Source test data on
diesel & dual fuels
Review of combustion controls and table on
percent NOX reductions
Review of NOX control technology
Review of criteria pollutant properties
Technical results of complete source test on a
diesel engine
Data supplement of Reference No. 5
Review of catalyst controls
Review of selective catalytic controls (on a
natural gas engine)
Source test data
Source test data (engines too small) (belongs in
AP-42 sect. 3.3)
Review of CO2 properties
Review of CO2 controls
Uses the same data from Reference No. 1
Parameter of Interest
Criteria
NOX
NOX
Criteria
Criteria, Non-Criteria, Organics,
Particulate, PM-10
Criteria, Non-Criteria, Organics,
Particulate, PM-10
NOX, CO, Organics
NOX
CO2, Organics
Organics
C02
CO2
Criteria
Raw Emission
Factor Data
Yes
No
No
No
Yes
Yes
No
No
Yes
Yes
No
No
Yes
-------
REFERENCES FOR CHAPTER 3
1. Technical Procedures for Developing AP-42 Emission Factors and Preparing AP-42
Sections, (Draft), Emission Inventory Branch, Technical Support Division, Office of
Air and Radiation, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, March 6,1992.
2. Standards Support and Environmental Impact Statement, Volume I: Stationary
Internal Combustion Engines, EPA-450/2-78-125a, Emission Standards and
Engineering Division, Office of Air, Noise, and Radiation, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, NC, July 1979.
3. Lips, H.I., J.A. Gotterba, and K. J. Lim, "Environmental Assessment of Combustion
Modification Controls for Stationary Internal Combustion Engines," EPA-600/7-81-
127, prepared by Acurex Corporation for Industrial Environmental Research
Laboratory, Office of Environmental Engineering and Technology, Office of Air
Quality Planning and Standards, U.S. Environmental Protection Agency, Research
Triangle Park, NC, July 1981.
4. Campbell, L.M., D.K. Stone, and G.S. Shareef, "Sourcebook: NOX Control
Technology Data," EPA-600/2-91-029, Radian for Control Technology Center,
Emission Standards Division, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, July 1991.
5. Hoggan, M., S. Cohanim, R. Sin, M. Hsu, and S. Tom, "Air Quality Trends in
California's South Coast and Southeast Desert Air Basins, 1976-1990, Air Quality
Management Plan, Appendix II-B," South Coast Air Quality Management District,
July 1991.
6. Castaldini, C., "Environmental Assessment of NOX Control on a Compression
Ignition Large Bore Reciprocating Internal Combustion Engine, Volume I:
Technical Results," EPA-600/7-86/001a, prepared by Acurex Corporation for the
Combustion Research Branch of the Energy Assessment and Control Division,
Industrial Environmental Research Laboratory, Office of Research and
Development, U.S. Environmental Protection Agency, Washington, DC, April 1984.
7. Castaldini, C., "Environmental Assessment of NOX Control on a Compression
Ignition Large Bore Reciprocating Internal Combustion Engine, Volume II: Data
Supplement," EPA-600/7-86/001b, prepared by Acurex Corporation for the
Combustion Research Branch of the Energy Assessment and Control Division,
Industrial Environmental Research Laboratory, Office of Research and
3-4
-------
REFERENCES FOR CHAPTER 3 (Continued)
Development, U.S. Environmental Protection Agency, Washington, DC, April 1984.
8. Catalysts for Air Pollution Control, brochure by the Manufacturers of Emission
Controls Association (MECA), Washington, DC, March 1992.
9. Castaldini, C., and L. R. Waterland, "Environmental Assessment of a Reciprocating
Engine Retrofitted with Selective Catalytic Reduction, Volume I: Technical
Results," EPA/600/7-86/014a, by Acurex Corporation for Air and Energy
Engineering Research Laboratories, Office of Research and Development, U.S.
Environmental Protection Agency, December 1984.
10. "Pooled Source Emission Test Report: Oil and Gas Production Combustion
Sources, Fresno and Ventura Counties, California," ENSR #7230-007-700, prepared
by ENSR Consulting and Engineering for Western States Petroleum Association
(WSPA), Bakersfield, CA, December 1990.
11. Osborn, W.E., and M.D. McDannel, "Emissions of Air Toxic Species: Test
Conducted Under AB2588 for the Western States Petroleum Association,"
CR 72600-2061, prepared by Carnot for Western States Petroleum Association
(WSPA), Glendale, California, May 1990.
12. "Limiting Net Greenhouse Gas Emissions in the United States, Volume II: Energy
Responses," DOE/PE-0101 Vol. II, Report for the Office of Environmental Analysis,
Office of Policy, Planning and Analysis, Department of Energy, September 1991.
13. "Limiting Net Greenhouse Gas Emissions in the United States, Volume I: Energy
Technologies," DOE/PE-0101 Vol. I, Report for the Office of Environmental
Analysis, Office of Policy, Planning and Analysis, Department of Energy, September
1991.
14. Shih, C.C., J.W. Hamersma, D.G. Ackerman, et al., "Emissions Assessment of
Conventional Stationary Combustion Systems, Volume II: Internal Combustion
Sources," EPA-600/7-79-029c, Report by TRW for Industrial Environmental
Research Laboratory, Office of Energy, Minerals, and Industry, U.S.
Environmental Protection Agency, February 1979.
3-5
-------
4. EMISSION FACTOR DEVELOPMENT
The unit(s) chosen for the emission factors was Ib (of pollutant)/MMBtu (energy
content of the fuel used), an input specific emission factor. Parallel SI units of ng/J were
also tabulated. The emission factors are also presented in an output specific emission
factor of g/hp-hr. To ensure the accuracy of the data for this revision, data without a brake
specific fuel consumption (BSFC) number or without enough information to calculate the
BSFC, were not used for calculations of the output specific emission factor in g/hp-hr.
However, the input specific emission factor was still calculated (providing there were
enough relevant data).
After all the data were ranked and entered into a table, the appropriate data were
averaged to produce an emission factor. All emission factors were reviewed and analyzed
based on EPA guidelines.1 The significant difference in definitions between data ranking
and emission factor ranking should be noted.
Definition of Emission Factor Rankings:
A - Developed only from A-rated source test data taken from many randomly
chosen facilities in the industry population. The source category is specific
enough to minimize variability within the source population.
B - Developed only from A-rated test data from a reasonable number of facilities.
Although no specific bias is evident, it is not clear if the facilities tested
represent a random sample of the industries. As with the A rating, the source
is specific enough to minimize variability within the source population.
C - Developed only from A- and B-rated test data from a reasonable number of
facilities. Although no specific bias is evident, it is not clear if the facilities
4-1
-------
tested represent a random sample of the industry. As with the A rating, the
source category is specific enough to minimize variability within the source
population.
D - The emission factor was developed only from A- and B-rated test data from a
small number of facilities, and there may be reason to suspect that these
facilities do not represent a random sample of the industry. There also may be
evidence of variability within the source population.
E - The emission factor was developed from C- and or D- rated test data, and there
may be reason to suspect that the facilities tested do not represent a random
sample of the industry. There also may be evidence of variability within the
source category population.
4.1 CRITERIA POLLUTANTS AND CARBON DIOXIDE
4.1.1 Review of Previous Data
A review of the previous criteria emission factors revealed that all data was taken
from the Standard Support and Environmental Impact Statement (SSEIS).2 This summary
report determined emission factors for stationary reciprocating internal combustion
engines fueled by diesel, dual fuel, or natural gas. The old data represented a computed
weight average based on sales of engine horsepower during the mid-1970s. There is no
documentation of the sales data nor any example calculations used in its derivation. The
baseline NOX and CO values are obtained from the SSEIS. For this update, the weighing
factors were eliminated and the unweighted emissions data used. The new emission factors
do not reflect any weighing factors.
In reviewing the raw data from the SSEIS, some of the CI engines used in the earlier
calculations had some engines rated as "greater than 350 in3/cylinder" or medium bore.
Since it is possible for an engine with >350 cubic inch displacement per cylinder
(CID/CYL) to have engine ratings of less than 600 hp (thus categorizing it in Section 3.3 of
AP-42, which includes medium bore engines), the decision was to not include these engines
in the current revision of Section 3.4. This set of data has been rated a data quality rating
of "C" because of the ambiguity of appropriate capacity designation.
4-2
-------
Although about half of the dual fuel engines have engine ratings of >350 CID/CYL,
the data were used in calculating the emission factor because there is no category for duel
fuels in Section 3.3 of AP-42 and by default would belong to Section 3.4. Since there is no
ambiguity of which section the data belong to in AP-42, the data were rated a quality of
"B" quality.
The SO2 emission factor is based on the assumption that all of the sulfur in fuel is
converted to SO2. Since the value was based on a valid assumption, it has been rated as
"B" quality data.
After reviewing the raw data, it was decided that NOX and CO from engines with
BSFC data and actual engine horsepower ratings will be used in the new revision of
emission factors for AP-42.
4.1.2 Review of New Data
There has been only two new data sets added to the current revision. One data set
cannot be used to calculate the g/hp-hr value because it appears that the engine was not
tested at full load.3 It could, however, be used to calculate the Ib/MMBtu emission for CO.
There is sufficient information to rate this source as of data quality "B." The other data
point is of "A" data quality and was obtained from a report on a 2100 hp diesel engine.4
Although there are data for CO2, an assumed value was used instead because the
accuracy and method of measurement for CO2 was not well defined. It was assumed that
all of the carbon going into the engine as fuel will appear in the exhaust as CO2. The
contribution of carbon to other gases (such as CO and hydrocarbons [typically less than 0.1
percent]) is small. The emission factor for CO2 will be a theoretical calculation of the
carbon content of the fuel and 100 percent conversion of C into CO2. Average carbon
content of natural gas and diesel will be 70 percent by weight for natural gas (which is
approximately 85 to 95 percent methane and the carbon content of methane is 75 percent
by weight) and 87 percent by weight for diesel.
Since there is no new data for dual fuel engines, the data from the SSEIS were used
(without the sales weighted factors). The old SOX value in g/hp-hr (based on assumptions)
was retained and an assumed BSFC value of 7163 Btu/hp-hr for dual fuel engines was used
4-3
-------
to calculate the Ib/MMBtu value.2
All formulas and assumptions used to make conversions and calculations are
presented in Appendix C.
An attempt was made to examine the utility of AP-42 based on horsepower ranges in
order to better estimate specific emissions for particular sources. Based on Figure 4-1,
there are currently insufficient data to minimize the scatter in the available data for
segregation of engines by horsepower to be meaningful.
4.1.3 Compilation of Baseline Emission Factors
Table 4-la (Reference 2) and 4-lb (Reference 3 and 4) for diesel engines and Table
4-2 for dual fuel engines provide summaries of criteria pollutant and CO2 emissions data.
4.1.4 Compilation of Controlled Emission Factors
There are many variables associated with the abatement of NOX emissions. Table 4-
3 shows the percentage of NOX reduction and fuel consumption penalties for diesel and dual
fuel engines.5'6'7
4.2 TOTAL ORGANIC COMPOUNDS AND AIR TOXICS
4.2.1 Review of Previous Data
In the previous version of AP-42, the TOCs were divided into methane and
nonmethane values. This classification was based on the assumptions that nonmethane
organic compounds is 90 percent of TOC from diesel engines and only 25 percent of TOC
emissions from dual fuel engines. Since the values were based upon assumptions, they
should be replaced with measured data. Without new data, the emission factor quality
rating based upon assumptions was rated as "E" quality.
4.2.2 Review of New Data
A new source was obtained for speciated TOC data, and it was determined to be of
"B" data quality for Ib/MMBtu values.3 This was from the source that did not appear to
be running at full load and will, therefore, not be used to calculate g/hp-hr
4-4
-------
values. With only one data point for speciated organic compounds, the emission factor
quality rating of "D" was given.
Another new source did not speciate the TOC data into comparable compounds to
the source mentioned above.4 It did, however speciate the TOC into "Cj," "C2," "C3," etc.,
and had a TOC value. By assuming Ct to be methane (CH4), there can be a separation of
methane and nonmethane emission values based upon measured data. This one data point
would upgrade the emission factor quality from "E" quality to "D." Since there is no new
data for dual fuel engines, the emission factor (based upon assumptions stated in Section
4.2.1) will have a emission factor quality rating of "E."
The trace element data obtained did not have a mass balance from lube and diesel
fuel analyses to the engine exhaust analysis.4 Therefore, there is no emission factor
included for trace elements in this revision of AP-42. Appendix B contains the data table of
the calculated trace metal throughput for future reference.
All formulas and assumptions used to make conversions and calculations are
presented in Appendix C.
4.2.3 Compilation of Emission Factors
Table 4-4 shows a summary of the organic compounds data for diesel and dual fuel
engines. Air toxics data for a diesel engine are summarized in Table 4-5.
4.3 PARTICULATE EMISSION AND SIZE DISTRIBUTION
4.3.1 Review of Previous Data
The previous particulate data in AP-42 were based on assumptions and a single
telephone communication. Since the value was based upon assumptions, it should be
replaced with real measured data. Without new data, the emission factor quality rating
based upon assumptions should continue to be rated as "E" quality.
4.3.2 Review of New Data
There was only one new source on particulate emission and size distribution. This
sole source is based upon a comprehensive study of one engine and is of "A" data quality.4
The particulate data were obtained using EPA Method 5, while the size distribution data
were obtained using a Source Assessment Sampling System (SASS). The two methods
4-5
-------
resulted in total particulate emissions having a difference of < 20 percent. This new data
will replace the old "E" quality data point, but because of the lack of additional data, the
emission factor rating must be "D" quality.
4.3.3 Compilation of Emission Factors
Particulate emission and size distribution emissions are shown on Table 4-6.
4-6
-------
TABLE 4-la. SUMMARY OF CRITERIA EMISSIONS DATA FOR DIESEL ENGINES3
Engine 24
Engine 62
Engine 43
Engine 56
Engine 55
Engine 41
Engine 42
Data
Rating
B
B
B
B
B
B
B
Units
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
Rating
610
711
1,100
1,300
1,336
1.650
1,650
BSFC
6,930
7,040
6,668
6,962
HHV
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
NOX
8.70
379
2.77
4.80
206
1.50
17.07
ERR"
ERR
8.80
399
2.91
7.30
317
2.31
12.88
ERR
ERR
14.74
ERR
ERR
CO
8.50
371
2.70
3.90
167
1.22
2.20
ERR
ERR
0.50
23
0.17
1.80
78
0.57
0.93
ERR
ERR
4.14
ERR
ERR
4-7
-------
TABLE 4-la. SUMMARY OF CRITERIA EMISSIONS DATA FOR DIESEL ENGINES3 (Continued)
Engine 17
Engine 15
Engine 3
Engine 57
Engine 58
Engine 18
Engine 52
Data
Rating
B
B
B
B
B
B
B
Units
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
Rating
2,200
2,410
2,475
2,675
2,800
3,300
3,631
BSFC
7,565
6,366
6,943
7,328
6,744
6,302
HHV
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
NOX
16.81
671
4.90
11.24
533
3.89
12.61
ERR
ERR
8.40
365
2.67
4.70
194
1.41
14.52
650
4.75
9.40
451
3.29
CO
3.83
153
1.12
3.02
143
1.05
1.19
ERR
ERR
1.30
57
0.41
1.80
74
0.54
1.14
51
0.37
4-8
-------
TABLE 4-la. SUMMARY OF CRITERIA EMISSIONS DATA FOR DIESEL ENGINES3 (Continued)
Engine 19
Engine 59
Engine 5
Engine 51
Engine 47
Data
Rating
B
B
B
B
B
Units
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
Rating
3,900
3,900
4,300
4,880
7,313
BSFC
6,888
6,677
6,650
6,485
HHV
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
19,300
137,030
NOX
11.87
ERR
ERR
7.90
346
2.53
10.99
497
3.63
8.50
386
2.82
9.70
452
3.30
CO
0.73
ERR
ERR
1.30
57
0.42
3.85
174
1.27
b.
Reference 2. Data for engines 8-12, 26-27, 35-36, 60, 68, 72-75, and 77 were determined to be "C" quality, but were not used
in emission factor development due to ambiguity of engine size.
ERR = Insufficient information was available to compute emissions.
4-9
-------
TABLE 4-lb. SUMMARY OF CRITERIA AND CO2 EMISSIONS DATA
FOR DIESEL ENGINES
Data Type/
or Pollutant
Data Rating
Rating
wt % S (Fuel)
%02
F factor
BSFC
HHV
NO,
CO
SOX
CO2
Units
hp
dscf/MMBtu
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
ppm
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
Ib/lOOOgal
Ib/MMBtu
WSPAa
B
850
0.03
10.2
9,157
19,479
138,300
308
55
0.40
55
0.40
TR-81-81"
A
2,100
0.19
13.7
9,220
7,009
18,943
134,497
11.0
465
3.46
0.96
41
0.30
0.41
17
0.13
a. Reference 3.
b. Reference 4.
4-10
-------
TABLE 4-2. SUMMARY OF CRITERIA EMISSIONS DATA FOR DUAL FUEL ENGINES3
Data Type/
or Pollutant
Data Rating
Rating
BSFC
HHV
NOX
CO
Units
hp
Btu/hp-hr
Btu/lb
Btu/gal
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
Engine
61
B
711
6,570
19,300
137,030
7.30
336
2.45
2.00
92
0.67
Engine
16
B
2,410
6,464
19,300
137,030
7.79
364
2.66
3.69
172
1.26
Engine
6
B
8,658
6,340
19,300
137,030
8.96
427
3.12
4.50
214
1.56
a. Reference 2. Data for engines 7, 13-14, 50, 76 and 78 were determined to be "B" quality, but were not used in
emission factor development due to ambiguity of engine size.
TABLE 4-3. NOX REDUCTION AND FUEL CONSUMPTION PENALTIES FOR DIESEL AND
DUAL FUEL ENGINES
Control Approach
Derate 10%
20%
25%
Retard 2°
4°
8°
Air/Fuel 3%
±10%
Water Injection 50%
(H2O/fuel ratio)
Selective Catalytic Reduction
(SCR)
Diesel
%NOI
Reduction
<20
5-23
<20
<40
28-45
7-8
25-35
80-95
ABSFC,a
%
4
1-5
4
4
2-8
3
2-4
0
Dual Fuel
%NOI
Reduction
<20
1-33
<20
<40
50-73
<20
25-40
80-95
ABSFC,a
%
4
1-7
3
1
3-5
0
1-3
0
BSFC = Brake Specific Fuel Consumption
4-11
-------
TABLE 4-4. SUMMARY OF ORGANIC COMPOUND EMISSIONS DATA FOR DIESEL AND
DUAL FUEL ENGINES
Data
Source/
Engine
TR-81-81
WSPA
Engine 24
Engine 62
Engine 43
Engine 56
Engine 55
Engine 41
Engine 42
Engine 17
Engine 15
Engine 3
Fuel
Type
D
D
D
D
D
D
D
D
D
D
D
D
Reference
4
3
2
2
2
2
2
2
2
2
2
2
Data
Rating
A
B
B
B
B
B
B
B
B
B
B
B
Units
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
ppm
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
Methane
0.03
1
0.01
Non
methane
0.33
14
0.10
HC: Total
Exhaust
(as CH4)
0.36
15
0.11
34.5
3.25
0.0235
0.25
11
0.08
0.18
8
0.06
0.37
ERRa
ERR
0.10
5
0.03
0.30
13
0.09
0.42
ERR
ERR
0.49
ERR
ERR
0.42
17
0.12
0.46
22
0.16
0.39
ERR
ERR
TABLE 4-4. SUMMARY OF ORGANIC COMPOUND EMISSIONS DATA FOR DIESEL AND
4-12
-------
DUAL FUEL ENGINES (Continued)
Engine
Engine 57
Engine 58
Engine 18
Engine 52
Engine 19
Engine 59
Engine 5
Engine 51
Engine 47
Engine 61
Engine 16
Engine 6
Fuel
Type
D
D
D
D
D
D
D
D
D
DF
DF
DF
Reference
2
2
2
2
2
2
2
2
2
2
2
2
Data
Rating
B
B
B
B
B
B
B
B
B
B
B
B
Units
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
HC: Total Exhaust
(as CH4)
0.30
13
0.10
0.20
8
0.06
0.42
19
0.14
0.27
13
0.09
0.37
ERR
ERR
0.50
22
0.16
0.13
6
0.04
0.31
14
0.10
0.17
8
0.06
1.50
69
0.50
5.67
265
1.93
5.16
246
1.79
Note: Reference 2: Data for engines 8-12, 26-27, 35-36, 60, 68, 72-75, and 77 were determined to be "C" quality, but
were not used; D = Diesel; DF = Dual Fuel.
in emission factor development due to ambiguity of engine size.
a. ERR = Insufficient information was available to compute emissions.
4-13
-------
TABLE 4-5. SUMMARY OF AIR TOXICS EMISSIONS DATA FOR A DIESEL ENGINE3
Data Type or Pollutant
Rating
wt % S (Fuel)
%o,
F factor
HHV
Benzene
Toluene
Xylenes
Propylene
Formaldehyde
Acetaldehyde
Acrolein
Naphthalene
Acenaphthylene
Acenaphthene
Units
hp
dscf/MMBtu
Btu/lb
Btu/gal
ppm
Ib/lOOOgal
Ib/MMBtu
ppm
Ib/lOOOgal
Ib/MMBtu
ppm
Ib/lOOOgal
Ib/MMBtu
ppm
Ib/lOOOgal
Ib/MMBtu
ppm
Ib/lOOOgal
Ib/MMBtu
ppm
Ib/lOOOgal
Ib/MMBtu
ppm
Ib/lOOOgal
Ib/MMBtu
^g/m3
Ib/lOOOgal
Ib/MMBtu
Mg/m3
Ib/lOOOgal
Ib/MMBtu
Mg/m3
Ib/lOOOgal
Ib/MMBtu
Data
850
0.03
10.2
9,157
19,479
138,300
0.213
0.1073
7.76E-04
0.064
0.0388
2.81E-04
0.040
0.0268
1.93E-04
1.433
0.3863
2.79E-03
0.057
0.0109
7.89E-05
0.012
0.0035
2.52E-05
0.003
0.0011
7.88E-06
116.91
0.0180
1.30E-04
8.27
0.0013
9.23E-06
4.19
0.0006
4.68E-06
4-14
-------
TABLE 4-5. SUMMARY OF AIR TOXICS EMISSIONS DATA FOR A DIESEL ENGINE3 (Continued)
Data Type or Pollutant
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benz(a)anthracene
Chrysene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Ideno(l,2,3-cd)pyrene
Dibenz(a,h)anthracene
Benzo(g,h,l)perylene
Units
Mg/ni3
Ib/lOOOgal
Ib/MMBtu
Mg/m3
Ib/lOOOgal
Ib/MMBtu
,wg/m3
Ib/lOOOgal
Ib/MMBtu
,wg/m3
Ib/lOOOgal
Ib/MMBtu
Mg/m3
Ib/lOOOgal
Ib/MMBtu
Mg/ni3
Ib/lOOOgal
Ib/MMBtu
,wg/m3
Ib/lOOOgal
Ib/MMBtu
,wg/m3
Ib/lOOOgal
Ib/MMBtu
Mg/ni3
Ib/lOOOgal
Ib/MMBtu
/^g/m3
Ib/lOOOgal
Ib/MMBtu
,wg/m3
Ib/lOOOgal
Ib/MMBtu
,wg/m3
Ib/lOOOgal
Ib/MMBtu
Mg/m3
Ib/lOOOgal
Ib/MMBtu
Data
11.49
0.0018
1.28E-05
36.58
0.0056
4.08E-05
1.11
0.0002
1.23E-06
3.62
0.0006
4.03E-06
3.33
0.0005
3.71E-06
0.56
0.0001
6.22E-07
1.37
0.0002
1.53E-06
1
0.0002
1.11E-06
<0.2
<3E-05
<2.18E-07
<0.23
<4E-05
<2.57E-07
<0.37
<0.0001
<4.14E-07
<0.31
<0.5E-05
<3.46E-07
<0.5
<0.0001
<5.56E-07
a.
Reference 3. All data are B quality.
4-15
-------
TABLE 4-6. SUMMARY OF PARTICULATE EMISSIONS DATA FOR
DIESEL ENGINES3
Data Type/
or Pollutant
PM Size Distribution
10/^m
Total
Total PM
Solids
Condensables
Total
Units
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
g/hp-hr
Ib/lOOOgal
Ib/MMBtu
Emission Factor
0.1520
6.4302
0.0478
0.0004
0.0169
0.0001
0.0054
0.2284
0.0017
0.0394
1.6668
0.0124
0.1972
8.3424
0.0620
0.2181
9.2265
0.0686
0.0245
1.0365
0.0077
0.2426
10.2630
0.0763
a. Reference 4
4-16
-------
REFERENCES FOR CHAPTER 4
1. Technical Procedures for Developing AP-42 Emission Factors and Preparing AP-42
Sections, (Draft), Emission Inventory Branch, Technical Support Division, Office of
Air and Radiation, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, March 6,1992.
2. "Standards Support and Environmental Impact Statement, Volume I: Stationary
Internal Combustion Engines," EPA-450/2-78-125a, Emission Standards and
Engineering Division, Office of Air, Noise, and Radiation, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, NC, July 1979.
3. "Pooled Source Emission Test Report: Oil and Gas Production Combustion
Sources, Fresno and Ventura Counties, California," ESNR #7230-007-700, prepared
by ENSR Consulting and Engineering for Western States Petroleum Association
(WSPA, Bakersfield, CA, December 1990.
4. Castaldini, C., "Environmental Assessment of NOX Control on a Compression
Ignition Large Bore Reciprocating Internal Combustion Engine, Volume I:
Technical Results," EPA-600/7-86/001a, prepared by Acurex Corp., for the
Combustion Research Branch of the Energy Assessment and Control Division,
Industrial Environmental Research Laboratory, Office of Research and
Development, U.S. Environmental Protection Agency, Washington, DC, April 1984.
5. Lips, H.I., J.A. Gotterba, and K. J. Lim, "Environmental Assessment of Combustion
Modification Controls for Stationary Internal Combustion Engines," EPA-450/2-78-
125a, Industiral Environmental Research Laboratory, Office of Environmental
Engineering and Technology, Office fo Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, July 1981.
6. Campbell, L.M., D.K. Stone, and G.S. Shareef, "Sourcebook: NOX Control
Technology Data," EPA-600/2-91-029, pp. 5-16, Control Technology Center,
Emission Standards Division, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, July 1991.
7. Catalysts for Air Pollution Control, brochure by the Manufacturers of Emission
Controls Association (MECA), Washington, DC, March 1992.
4-17
-------
5. AP-42 SECTION 3.4: LARGE STATIONARY DIESEL & ALL
STATIONARY DUAL FUEL ENGINES
The revision to Section 3.4 of AP-42 is presented in the following pages as it would
appear in the document.
5-1
-------
3.4 LARGE STATIONARY DIESEL AND ALL STATIONARY DUAL FUEL ENGINES
3.4.1 General
The primary domestic use of large stationary diesel engines (greater than 600 hp) is in oil
and gas exploration and production. These engines, in groups of three to five, supply mechanical
power to operate drilling (rotary table), mud pumping and hoisting equipment, and may also
operate pumps or auxiliary power generators. Another frequent application of large stationary
diesels is electricity generation for both base and standby service. Smaller uses include irrigation,
hoisting and nuclear power plant emergency cooling water pump operation.
Dual fuel engines were developed to obtain compression ignition performance and the
economy of natural gas, using a minimum of 5 to 6 percent diesel fuel to ignite the natural gas.
Large dual fuel engines have been used almost exclusively for prime electric power generation.
This section includes all dual fuel engines.
3.4.2 Process Description
All reciprocating internal combustion (1C) engines operate by the same basic process. A
combustible mixture is first compressed in a small volume between the head of a piston and its
surrounding cylinder. The mixture is then ignited, and the resulting high pressure products of
combustion push the piston through the cylinder. This movement is converted from linear to
rotary motion by a crankshaft. The piston returns, pushing out exhaust gases, and the cycle is
repeated.
There are two methods used for stationary reciprocating 1C engines: compression ignition
(CI) and spark ignition (SI). Section 3.4 deals only with compression ignition engines.
In compression ignition engines, combustion air is first compression heated in the cylinder,
and diesel fuel oil is then injected into the hot air. Ignition is spontaneous as the air is above the
auto-ignition temperature of the fuel. Spark ignition engines initiate combustion by the spark of
an electrical discharge. 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 burn any mixture ratio of gas and
diesel oil (hence the name dual fuel), from 6- to 100-percent diesel oil.
CI engines usually operate at a higher compression ratio (ratio of cylinder volume when the
piston is at the bottom of its stroke to the volume when it is at the top) than SI engines because fuel
is not present during compression; hence there is no danger of premature auto-ignition. Since
engine thermal efficiency rises with increasing pressure ratio (and pressure ratio varies directly
with compression ratio), CI engines are more efficient than SI engines. This increased efficiency is
gained at the expense of poorer response to load changes and a heavier structure to withstand the
higher pressures.
4/93 Stationary Internal Combustion Sources 3.4-1
-------
3.4.3 Emissions and Controls
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 (CI) engines enter the atmosphere from the exhaust. Crankcase blowby is minor because
hydrocarbons are not present during compression of the charge. Evaporative losses are
insignificant in diesel engines due to the low volatility of diesel fuels. In general, evaporative losses
are also negligible in engines using gaseous fuels because these engines receive their fuel
continuously from a pipe rather than via a fuel storage tank and fuel pump.
The primary pollutants from internal combustion engines are oxides of nitrogen (NOX),
organic compounds (hydrocarbons), carbon monoxide (CO), and particulates, which include both
visible (smoke) and nonvisible emissions. The other pollutants are primarily the result of
incomplete combustion. Ash and metallic additives in the fuel also contribute to the particulate
content of the exhaust. Oxides of sulfur (SOX) also appears in the exhaust from 1C engines.
The primary pollutant of concern from large stationary diesel and all stationary dual fuel
engines is NOX, which readily forms in the high temperature, pressure, nitrogen content of the fuel,
and excess air environment found in these engines. Lesser amounts of CO and organic compounds
are emitted. The sulfur compounds, mainly SO2, are directly related to the sulfur content of the
fuel. SOX emissions will usually be quite low because of the negligible sulfur content of diesel fuels
and natural gas.
Tables 3.4-1 (English units) and 3.4-2 (Metric units) contain gaseous emission factors.
Table 3.4-3 shows the speciated organic compound emission factors and Table 3.4-4 shows
the emission factors for polycyclic aromatic hydrocarbons (PAH). These tables do not provide a
complete speciated organic compound and PAH listing since they are based only on a single engine
test; they are to be used for rough order of magnitude comparisons.
Table 3.4-5 shows the particulate and particle sizing emission factors.
Control measures to date have been directed mainly at limiting NOX emissions because NOX
is the primary pollutant from diesel and dual fuel engines. Table 3.4-6 shows the NOX reduction
and fuel consumption penalties for diesel and dual fueled engines based on some of the available
control techniques. All of these controls are engine control techniques except for the selective
catalytic reduction (SCR) technique, which is a post-combustion control. The emission reductions
shown are those which have been demonstrated. The effectiveness of controls on an particular
engine will depend on the specific design of each engine and the effectiveness of each technique
could vary considerably. Other NOX control techniques exist but are not included in Table 3.4-6.
These techniques include internal/external exhaust gas recirculation (EGR), combustion chamber
modification, manifold air cooling, and turbocharging.
3.4-2 EMISSION FACTORS 4/93
-------
TABLE 3.4-1. (ENGLISH UNITS) GASEOUS EMISSION FACTORS FOR LARGE STATIONARY DIESEL
AND ALL STATIONARY DUAL FUEL ENGINES3
(Source Classification Codes)
Pollutant
Diesel Fuel
(SCC 20200401)
[grams/hp-hr]
(power output)
[Ib/MMBtu]
(fuel input)
Emission Factor
Rating0
Dual Fuel"
(SCC 20200402)
[grams/hp-hr]
(power output)
[Ib/MMBtu]
(fuel input)
Emission
Factor Rating0
NOX
CO
SO/
CO2e
TOC,f(asCH4)
Methane
Nonmethane
11
2.4
3.67Sj
524
0.32
0.03
0.33
3.1
0.81
1.01S,
165
0.09
0.01
0.10
C
C
B
B
C
Eg
Eg
9.2
2.3
0.184S1 + 4.34S2
350
2.4
1.8
0.6
3.1
0.79
O.OSSj + 0.895S2
110
0.8
0.6
0.2
D
D
B
B
D
Eh
Eh
aData are based on uncontrolled levels for each fuel from references 4,5, and 6. When necessary, the average heating value of diesel was assumed to
be 19300 Btu/lb with a density of 7.1 Ib/gal. The power output and fuel input values were averaged independently from each other due to the use of
actual Brake Specific Fuel Consumption values for each data point and the use of data that may have enough information to calculate only one of
the two emission factors (e.g., if there was enough information to calculate Ib/MMBtu, but not enough to calculate the g/hp-hr). The emission factors
are based on averages across all manufacturers and duty cycles. The actual emissions from a particular engine or manufacturer could vary
considerably from these levels.
bDual fuel is based on a mixture of 95 percent natural gas and 5 percent diesel fuel.
C"D" and "E" rating for emission factors are due to limited data sets, inherent variability in the population and/or a lack of documentation of test
results. "D" and "E" rated emission factors may not be suitable for specific facilities or populations and should be used with care.
""Emission factors are based on the assumption that all sulfur in the fuel is converted to SO2. Sj = percent sulfur in diesel fuel; S2 = percent sulfur in
gas.
"Based on assumed 100 percent conversion of carbon in fuel to CO2 with 87 weight percent carbon in diesel, 70 weight percent carbon in natural gas,
dual fuel mixture of 5 percent diesel with 95 percent natural gas, average brake specific fuel consumption of 7000 Btu/hp-hr, diesel heating value of
19,300 Btu/lb, and natural gas heating value of 23,900 Btu/lb.
'Total Organic Compounds.
gBased on emissions data from one engine.
hBased on the assumption that nonmethane organic compounds are 25 percent of TOC emissions from dual fuel engines. Molecular weight of
nonmethane gas stream is assumed to be that of methane.
-------
TABLE 3.4-2. (METRIC UNITS) GASEOUS EMISSION FACTORS FOR LARGE STATIONARY DIESEL AND
ALL STATIONARY DUAL FUEL ENGINES3
(Source Classification Codes)
Pollutant
Diesel Fuel
(SCC 20200401)
[g/kW-hr]
(power output)
[ng/J]
(fuel input)
Emission Factor
Rating0
Dual Fuel"
(SCC 20200402)
[g/kW-hr]
(power output)
[ng/J]
(fuel input)
Emission Factor
Rating0
NOX
CO
SO/
CO2e
TOC,f(asCH4)
Methane
Nonmethane
14
3.2
4.92Sj
703
0.43
0.04
0.44
1,322
349
434S,
70,942
38
4
45
C
C
B
B
C
Eg
Eg
12.3
3.1
0.25SJ + 4.34SJ
469
3.2
2.4
0.8
1,331
340
21.7S1 + 384S2
47,424
352
240
80
D
D
B
B
D
Eh
Eh
aData are based on uncontrolled levels for each fuel from references 4,5, and 6. When necessary, the average heating value of diesel was assumed to
be 19300 Btu/lb with a density of 7.1 Ib/gal. The power output and fuel input values were averaged independently from each other due to the use of
actual Brake Specific Fuel Consumption values for each data point and the use of data that may have enough information to calculate only one of
the two emission factors (e.g., if there was enough information to calculate Ib/MMBtu, but not enough to calculate the g/hp-hr). The emission
factors are based on averages across all manufacturers and duty cycles. The actual emissions from a particular engine or manufacturer could vary
considerably from these levels.
bDual fuel is based on 95 percent natural gas and 5 percent diesel fuel.
C"D" and "E" rating for emission factors are due to limited data sets, inherent variability in the population and/or a lack of documentation of test
results. "D" and "E" rated emission factors may not be suitable for specific facilities or populations and should be used with care.
""Emission factors are based on the assumption that all sulfur in the fuel is converted to SO2. Sj = percent sulfur in fuel oil; S2 = percent sulfur in gas.
eBased on assumed 100 percent conversion of carbon in fuel to CO2 with 87 weight percent carbon in diesel, 70 weight percent carbon in natural gas,
dual fuel mixture of 5 percent diesel with 95 percent natural gas, average brake specific fuel consumption of 7000 Btu/hp-hr, diesel heating value of
19,300 Btu/lb, and natural gas heating value of 23,900 Btu/lb.
'Total Organic Compounds.
gBased on emissions data from one engine.
hBased on the assumption that nonmethane organic compounds are 25 percent of TOC emissions from dual fuel engines. Molecular weight of
nonmethane gas stream is assumed to be that of methane.
-------
TABLE 3.4-3. (ENGLISH AND METRIC UNITS) SPECIATED ORGANIC COMPOUND
EMISSION FACTORS FOR LARGE STATIONARY DIESEL ENGINES3
(Source Classification Code: 20200401)
(Emission Factor Rating: E)b
Pollutant
Benzene
Toluene
Xylenes
Propylene
Formaldehyde
Acetaldehyde
Acrolein
[Ib/MMBtu]
(fuel input)
7.76 E-04
2.81 E-04
1.93 E-04
2.79 E-03
7.89 E-05
2.52 E-05
7.88 E-06
[ng/J]
(fuel input)
3.34 E-01
1.21 E-01
8.30 E-02
1.20 E-00
3.39 E-02
1.08 E-02
3.39 E-03
"Data based on the uncontrolled levels of one diesel engine from reference 5. There was enough
information to compute the input specific emission factors of Ib/MMBtu, but not enough to
calculate the output specific emission factor of g/hp-hr. There was enough information to
compute the input specific emission factors of ng/J, but not enough to calculate the output
specific emission factor of g/kW-hr.
b"E" rating for emission factors are due to limited data sets, inherent variability in the population
and/or a lack of documentation of test results. "E" rated emission factors may not be suitable
for specific facilities or populations and should be used with care.
4/93 Stationary Internal Combustion Sources 3.4-5
-------
TABLE 3.4-4. (ENGLISH AND METRIC UNITS) POLYCYCLIC AROMATIC
HYDROCARBON (PAH) EMISSION FACTORS FOR LARGE STATIONARY DIESEL
ENGINES3
(Source Classification Code: 20200401)
(Emission Factor Rating: E)b
Pollutant
Polycyclic Aromatic Hydrocarbons
(PAH)
Naphthalene
Acenaphthylene
Acenaphthene
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benz(a)anthracene
Chrysene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Indeno(l,2,3-cd)pyrene
Dibenz(a,h)anthracene
Benzo(g,h,l)perylene
Total PAH
[Ib/MMBtu]
(fuel input)
1.30 E-04
9.23 E-06
4.68 E-06
1.28 E-05
4.08 E-05
1.23 E-06
4.03 E-06
3.71 E-06
6.22 E-07
1.53 E-06
1.11 E-06
< 2.18 E-07
< 2.57 E-07
< 4.14 E-07
< 3.46 E-07
< 5.56 E-07
2.12 E-04
[ng/J]
(fuel input)
5.59 E-02
3.97 E-03
2.01 E-03
5.50 E-03
1.75 E-02
5.29 E-04
1.73 E-03
1.60 E-03
2.67 E-04
6.58 E-04
4.77 E-04
< 9.37 E-05
< 1.10 E-04
< 1.78 E-04
< 1.49 E-04
< 2.39 E-04
9.09 E-02
"Data are based on the uncontrolled levels of one diesel engine from reference 5. There was enough
information to compute the input specific emission factors of Ib/MMBtu and ng/J but not
enough to calculate the output specific emission factor of g/hp-hr and g/kW-hr.
b"E" rating for emission factors is due to limited data sets, inherent variability in the population
and/or a lack of documentation of test results. "E" rated emission factors may not be suitable
for specific facilities or populations and should be used with care.
3.4-6 EMISSION FACTORS 4/93
-------
TABLE 3.4-5. (ENGLISH AND METRIC UNITS) PARTICULATE AND PARTICLE SIZING
EMISSION FACTORS FOR LARGE STATIONARY DIESEL ENGINES3
(Source Classification Code: 20200401)
(Emission Factor Rating: E)b
Pollutant
Particulate Size
Distribution
<1 um
1-3 um
3-10 um
>10 urn
Total PM-10 (<10 urn)
TOTAL
Particulate Emissions
Solids
Condensables
TOTAL
Power
[grams/hp-hr]
0.1520
0.0004
0.0054
0.0394
0.1578
0.1972
0.2181
0.0245
0.2426
Output
[grams/kW-hr]
0.2038
0.0005
0.0072
0.0528
0.2116
0.2644
0.2925
0.0329
0.3253
Fuel Input
flb/MMBtu]
0.0478
0.0001
0.0017
0.0124
0.0496
0.0620
0.0686
0.0077
0.0763
fng/Jl
20.56
0.05
0.73
5.33
21.34
26.67
29.49
3.31
32.81
"Data are based on the uncontrolled levels of one diesel engine from reference 6. The data for the
particulate emissions were collected using Method 5 and the particle size distributions were
collected using a Source Assessment Sampling System (SASS).
b"E" rating for emission factors is due to limited data sets, inherent variability in the population
and/or a lack of documentation of test results. "E" rated emission factors may not be suitable for
specific facilities or populations and should be used with care.
4/93
Stationary Internal Combustion Sources
3.4-7
-------
TABLE 3.4-6. NOX REDUCTION AND FUEL CONSUMPTION PENALTIES FOR
LARGE STATIONARY DIESEL AND DUAL FUEL ENGINES3
(Source Classification Codes)
Control Approach
Diesel
(SCC 20200401)
Percent NOX
Reduction
ABSFC,"
Percent
Dual Fuel
(SCC 20200402)
Percent
NOX
Reduction
ABSFC,"
Percent
Derate
Retard
Air-to-Fuel
Water Injection (H2O/fuel ratio)
Selective Catalytic Reduction (SCR)
10%
20%
25%
2°
4°
8°
3%
±10%
50%
<20
5-23
<20
<40
28-45
7-8
25-35
80-95
4
1-5
4
4
2-8
3
2-4
0
<20
1-33
<20
<40
50-73
<20
25-40
80-95
4
1-7
3
1
3-5
0
1-3
0
"Data are based on references 1, 2, and 3. The reductions shown are typical and will vary depending
on the engine and duty cycle.
bBSFC = Brake Specific Fuel Consumption.
3.4-8
EMISSION FACTORS
4/93
-------
References for Section 3.4
1. Lips, H.I., J.A. Gotterba, and K.J. Lim, Environmental Assessment of Combustion
Modification Controls for Stationary Internal Combustion Engines, EPA-600/7-81-127,
Industrial Environmental Research Laboratory, Office of Environmental Engineering and
Technology, Office of Air Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, NC, July 1981,
2. Campbell, L.M., O.K. Stone, and G.S. Shareef, Sourcebook: NO^ Control Technology Data,
Control Technology Center, EPA-600/2-91-029, Emission Standards Division, Office of Air
Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, NC, July 1991.
3. Catalysts for Air Pollution Control, brochure by the Manufacturers of Emission Controls
Association (MECA), Washington, DC, March 1992.
4. Standards Support and Environmental Impact Statement, Volume I: Stationary Internal
Combustion Engines, EPA-450/2-78-125a, Emission Standards and Engineering Division,
Office of Air, Noise, and Radiation, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, July 1979.
5. Pooled Source Emission Test Report: Oil and Gas Production Combustion Sources, Fresno
and Ventura Counties, California, Report prepared by ENSR Consulting and Engineering for
Western States Petroleum Association (WSPA), Bakersfield, CA, December 1990, ENSR #
7230-007-700.
6. Castaldini, C., Environmental Assessment of NO^ Control on a Compression Ignition Large
Bore Reciprocating Internal Combustion Engine, Volume I: Technical Results, EPA-600/7-
86/OOla, Combustion Research Branch of the Energy Assessment and Control Division,
Industrial Environmental Research Laboratory, Office of Research and Development, U.S.
Environmental Protection Agency, Washington, DC, April 1984.
4/93 Stationary Internal Combustion Sources 3.4-9
-------
APPENDIX A
SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE
-------
TABLE A-l SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE
COMPANY/AGENCY
CONTACT PERSON
KANSAS DEPT. OF HEALTH AND ENVIRONMENT
MANUFACTURERS OF EMISSION CONTROLS ASSOCIATION (MECA)
EPA OFFICE OF MOBILE SOURCES, ANN ARBOR, MI
AMERICAN PETROLEUM INSTITUTE (API)
INDUSTRIAL GAS CLEANING INSTITUTE (IGCI)
MONTEREY BAY AIR POLLUTION CONTROL DISTRICT
SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT (SCAQMD)
ENGINE MANUFACTURERS ASSOCIATION (EMA)
AMERICAN HONDA
AMERICAN SUZUKI MOTOR CORPORATION
BRIGGS & STRATTON CORPORATION
CATERPILLAR INC.
CUMMINS ENGINE COMPANY
DEERE & COMPANY
DETROIT DIESEL CORPORATION
DEUTZ CORPORATION
FORD NEW HOLLAND
FORD POWER PRODUCTS DIVISION
GENERAL ELECTRIC
GENERAL MOTORS CORPORATION
ISUZU MOTORS AMERICA, INC.
KAWASAKI MOTORS CORP.
KOHLER COMPANY
KOMATSU LTD.
KUBOTA CORPORATION
LISTER-FETTER, INC.
MITSUBISHI ENGINE NORTH AMERICA, INC.
ONAN CORPORATION
TECUMSEH PRODUCTS COMPANY
TELEDYNE TOTAL POWER
YANMAR DIESEL AMERICA
COOPER AJAX/SUPERIOR DIVISION
TEXAS AIR CONTROL BOARD
HARISH AGARWAL,
MR HINTHER
CAROLYN GILLESPIE,
RAYMOND CONNOR
GREGJANSSEN,
KEVIN GREEN
JIM WILLIAMS
JEFF SMITH
LARRY BORELLI
BILL DENNISON
GLENN KELLER
VIA EMA
VIA EMA
VIA EMA
DON DOWDALL
MIKE BRAND
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
VIA EMA
BRUCE CHRISMANN
RANDY HAMILTON
A-2
-------
TABLE A-l SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE (Continued)
COMPANY/AGENCY
CONTACT PERSON
UTAH AIR QUALITY BOARD
WAUKESHA
FLORIDA DEPARTMENT OF ENVIRONMENTAL REGULATIONS
COOPER BESSEMER
BAY AREA AIR QUALITY MANAGEMENT DISTRICT
KANSAS EPA, AIR TOXICS DIVISION
NEW YORK EPA
FAIRBANKS MORSE ENGINE DIVISION
MISSOURI NATURAL RESOURCE AIR POLLUTION CONTROL PROGRAM
DIESEL ENGINE MANUFACTURERS ASSOCIATION (DEMA)
VENTURA COUNTY AIR POLLUTION CONTROL DISTRICT
WESTERN STATES PETROLEUM ASSOCIATION (WSPA)
FRESNO COUNTY AIR POLLUTION CONTROL DISTRICT
NORTH COAST UNIFIED AIR QUALITY MANAGEMENT DIST.
SACRAMENTO METROPOLITAN AIR QUALITY MANAGEMENT DISTRICT
SAN JOAQUIN COUNTY AIR POLLUTION CONTROL DISTRICT
CALAVERAS COUNTY AIR POLLUTION CONTROL DISTRICT
LAKE COUNTY AIR QUALITY MANAGEMENT DISTRICT
LASSEN COUNTY AIR POLLUTION CONTROL DISTRICT
DON ROBINSON,
NORMAN ERICKSON
PAUL CANNESTRA
CLAIR FANCY
BILL HEATER
STEVE HILL,
BOB NISHIMURA,
MARK NASH
ED BUCKNER
FRANKJON
PAUL DANYLUK
TODD CRAWFORD
TERRI THOMAS
MIKE EMANUEL
ROBERT DOWELL
BOB CLARK
BRUCE NIXON
LAKHMIR GREWAL
ROBERT MARSHALL
ROBERT REYNOLDS
KENNETH SMITH
A-3
-------
APPENDIX B
TRACE ELEMENT DATA
-------
Trace Element Emissions Section 3.4 BASED ON: BSFC = 7,009 Btu/hph
(Based on 1 engine) HHV = 134,497 Btu/gal
05/14/92 Engine= 2,100 hp
| RAW DATA 1
| Lube Oil 1| -Diesel Fuel 1| Exhaust 1 Lube Oil Fuel Exhaust %Out 0-50% Out >50-150%Out
g/hp-hr Ib/Mgal Ib/MMBtu g/hp-hr Ib/Mgal Ib/MMBtu g/hp-hr Ib/Mgal Ib/MMBtu ug/s ug/s ug/s ========
Aluminum 4.29E-07 1.81E-05 1.35E-07 >3.60E-03 >1.52E-01 >1.13E-03 >3.94E-03 >1.67E-01 >1.24E-03 0.25 > 2100 > 2300 110% 110%Aluminum
Antimony 1.20E-08 5.08E-07 3.77E-09 9.94E-07 4.21E-05 3.13E-07 0.007 0.58 8286%
Arsenic 6.00E-07 2.54E-05 1.89E-07 5.49E-07 2.32E-05 1.73E-07 0.35 0.32 91% 91% Arsenic
Barium 3.09E-05 1.31E-03 9.71E-06 1.34E-04 5.66E-03 4.21E-05 4.97E-06 2.10E-04 1.56E-06 18 78 2.9 3% 3%Barium
Beryllium <6.86E-09 <2.90E-07<2.16E-09 <5.49E-08 <2.32E-06 <1.73E-08 < 0.004 < 0.032 800%
Bismuth <5.49E-08 <2.32E-06 <1.73E-08 < 0.032
Boron <6.86E-09<2.90E-07<2.16E-09 3.43E-06 1.45E-04 1.08E-06 6.17E-05 2.61E-03 1.94E-05 < 0.004 2 36 1796%
Bromine 4.29E-07 1.81E-05 1.35E-07 6.69E-05 2.83E-03 2.10E-05 2.57E-05 1.09E-03 8.09E-06 0.25 39 15 38% 38% Bromine
Cadmium 4.29E-08 1.81E-06 1.35E-08 <1.05E-05 <4.42E-04 <3.29E-06 0.025 < 6.1 24400%
Calcium >6.00E-05 >2.54E-03 >1.89E-05 8.57E-03 3.63E-01 2.70E-03 3.94E-03 1.67E-01 1.24E-03 > 35 5000 2300 46% 46% Calcium
Cerium 4.97E-07 2.10E-05 1.56E-07 0.29
Cesium 6.86E-09 2.90E-07 2.16E-09 <5.49E-07 <2.32E-05 <1.73E-07 0.004 < 0.32 8000%
Chlorine 3.26E-05 1.38E-03 1.02E-05 1.17E-04 4.93E-03 3.67E-05 4.97E-05 2.10E-03 1.56E-05 19 68 29 33% 33% Chlorine
Chromium 4.11E-06 1.74E-04 1.29E-06 8.40E-06 3.55E-04 2.64E-06 1.49E-05 6.31E-04 4.69E-06 2.4 4.9 8.7 119% 119%Chromium
Cobalt 4.29E-07 1.81E-05 1.35E-07 1.34E-05 5.66E-04 4.21E-06 1.47E-06 6.24E-05 4.64E-07 0.25 7.8 0.86 11% 11% Cobalt
Copper 3.09E-06 1.31E-04 9.71E-07 1.01E-04 4.28E-03 3.18E-05 4.63E-04 1.96E-02 1.46E-04 1.8 59 270 444%
Fluorine 1.22E-07 5.15E-06 3.83E-08 3.43E-05 1.45E-03 1.08E-05 2.57E-05 1.09E-03 8.09E-06 0.071 20 15 75% 75% Fluorine
Gallium 3.09E-08 1.31E-06 9.71E-09 2.40E-06 1.02E-04 7.55E-07 0.018 1.4 7778%
Germanium <5.49E-07 <2.32E-05 <1.73E-07 < 0.32
Iodine <4.97E-06<2.10E-04<1.56E-06 1.10E-07 4.64E-06 3.45E-08 < 2.9 0.064 2% 2% Iodine
Iron 5.14E-05 2.18E-03 1.62E-05 1.68E-03 7.11E-02 5.28E-04 1.49E-03 6.31E-02 4.69E-04 30 980 870 86% 86%Iron
Lanthanum 1.89E-08 7.98E-07 5.93E-09 1.47E-06 6.24E-05 4.64E-07 0.011 0.86 7818%
Lead 6.00E-07 2.54E-05 1.89E-07 3.43E-05 1.45E-03 1.08E-05 5.14E-06 2.18E-04 1.62E-06 0.35 20 3 15% 15% Lead
Lithium 4.29E-08 1.81E-06 1.35E-08 1.01E-05 4.28E-04 3.18E-06 4.46E-07 1.89E-05 1.40E-07 0.025 5.9 0.26 4% 4%Lithium
Magnesium 1.89E-06 7.98E-05 5.93E-07 3.43E-04 1.45E-02 1.08E-04 1.59E-04 6.74E-03 5.01E-05 1.1 200 93 46% 46% Magnesium
Manganese 3.09E-07 1.31E-05 9.71E-08 3.43E-05 1.45E-03 1.08E-05 3.94E-05 1.67E-03 1.24E-05 0.18 20 23 114% 114%Manganese
Mercury <4.97E-04<2.10E-02 <1.56E-04 <290
Molybdenum 2.40E-07 1.02E-05 7.55E-08 3.43E-04 1.45E-02 1.08E-04 5.14E-06 2.18E-04 1.62E-06 0.14 200 3 1% l%Molybdenum
Neodymium 1.47E-06 6.24E-05 4.64E-07 0.86
Nickel 1.22E-06 5.15E-05 3.83E-07 1.17E-04 4.93E-03 3.67E-05 8.40E-05 3.55E-03 2.64E-05 0.71 68 49 71% 71%Nickel
Niobium <4.97E-07 <2.10E-05 <1.56E-07 < 0.29
Phosphorus 3.60E-06 1.52E-04 1.13E-06 1.17E-03 4.93E-02 3.67E-04 >4.46E-03 >1.89E-01 >1.40E-03 2.1 680 > 2600 381%
Potassium >6.00E-05 >2.54E-03 >1.89E-05 7.37E-03 3.12E-01 2.32E-03 >8.06E-03 >3.41E-01 >2.53E-03 > 35 4300 > 4700 108% 108%Potassium
Rubidium 2.40E-08 1.02E-06 7.55E-09 4.46E-06 1.89E-04 1.40E-06 0.014 2.6 18571%
Samarium 5.49E-08 2.32E-06 1.73E-08 0.032
Scandium 1.20E-08 5.08E-07 3.77E-09 <3.43E-06 <1.45E-04 <1.08E-06 4.97E-05 2.10E-03 1.56E-05 0.007 < 2 29 1445%
Selenium 1.89E-07 7.98E-06 5.93E-08 1.47E-04 6.24E-03 4.64E-05 0.11 86 78182%
Silicon 5.83E-05 2.47E-03 1.83E-05 2.57E-03 1.09E-01 8.09E-04 2.06E-03 8.70E-02 6.47E-04 34 1500 1200 78% 78% Silicon
Silver 6.86E-09 2.90E-07 2.16E-09 6.34E-05 2.68E-03 2.00E-05 0.004 37 925000%
Sodium >6.00E-05 >2.54E-03 >1.89E-05 1.68E-04 7.11E-03 5.28E-05 >4.63E-03 >1.96E-01 >1.46E-03 > 35 98 > 2700 2030%
Strontium 1.39E-05 5.87E-04 4.37E-06 1.68E-05 7.11E-04 5.28E-06 9.94E-06 4.21E-04 3.13E-06 8.1 9.8 5.8 32% 32% Strontium
Sulfur >5.83E-03 >2.47E-01 >1.83E-03 3.26E-01 1.38E+01 1.02E-01 >7.03E-03 >2.97E-01 >2.21E-03 > 3400 190000 > 4100 2% 2% Sulfur
Tellurium 2.74E-07 1.16E-05 8.63E-08 0.16
Tin 1.22E-07 5.15E-06 3.83E-08 3.43E-05 1.45E-03 1.08E-05 0.071 20 28169%
Titanium 4.29E-06 1.81E-04 1.35E-06 3.43E-04 1.45E-02 1.08E-04 1.53E-04 6.45E-03 4.80E-05 2.5 200 89 44% 44% Titanium
Tungsten <1.68E-05 <7.11E-04<5.28E-06 < 9.8 0% 0%
-------
Vanadium 2.40E-08 1.02E-06 7.55E-09 6.69E-06 2.83E-04 2.10E-06 4.97E-07 2.10E-05 1.56E-07 0.014 3.9 0.29 7% 7% Vanadium
Yttrium <4.97E-07 <2.10E-05 <1.56E-07 < 0.29
Zinc 1.08E-05 4.57E-04 3.40E-06 1.51E-04 6.38E-03 4.75E-05 4.80E-04 2.03E-02 1.51E-04 6.3 88 280 297%
Zirconium 1.51E-05 6.38E-04 4.75E-06 6.17E-06 2.61E-04 1.94E-06 8.8 3.6 41% 41%Zirconium
4/93 Stationary Internal Combustion SourceB-3
-------
APPENDIX C
FORMULAS AND ASSUMPTIONS USED TO CONVERT AND
CALCULATE EMISSION FACTORS
-------
Convention used:l/hp/hr = 1/hp-hr
Assumptionsrlf needed (see Appendix E):
Heating value of diesel is 19300 Btu/lb
Heating value of natural gas is 23900 Btu/lb
Density of diesel is 7.1 Ib/gal
Weight % of carbon in diesel is 87%
Weight % of carbon in natural gas is 70%
For dual fuels, mixture of 5% diesel with 95% natural gas
Average brake specific fuel consumption (BSFC) = 7000 Btu/np-hr
To convert from heat input (MMBtu/hr) to BSFC (Btu/hp-hr)
Assumptions: Engine is running at full load (in hp)
(heat input)*(l/(engine rating in hp)) = BSFC
(MMBtu/hr)*(1000000 Btu/MMBtu)*(l/hp) = Btu/hp/hr = Btu/hp-hr
To convert from g/hp-hr to Ib/MMBtu
Assumptions: You have BSFC (Btu/hp-hr)
(g/hp-hr)*(l/(Btu/hp-hr))*(l lb/453.6 g)*(1000000 Btu/MMBtu) = Ib/MMBtu
To calculate heating value (Btu/lb) from BSFC (Ib/hp-hr) and fuel rate (Btu/hp-hr)
(Btu/hp-hr)*(l/(lb/hp-hr)) = Btu/lb
To convert heating values of Btu/lb to Btu/gal and visa versa
Assumptions: Density = 7.1 Ib/gal
(Btu/lb)*(7.1 Ib/gal) = Btu/gal
(Btu/gal)/(7.1 Ib/gal) = Btu/lb
To convert from g/hp-hr to Ib/MMBtu
Assumptions: You have the heat input value (MMBtu/hr)
Engine is running at full load (in hp)
(g/hp-hr)*(l/(MMBtu/hr))*(hp)*(l lb/453.6 g) = Ib/MMBtu
To convert from g/hp-hr to Ib/Mgal (where Mgal = 1000 gal)
Assumptions: You have BSFC (Btu/hp-hr) and heating value (Btu/gal)
C-2
-------
(g/hp-hr)*(l/(Btu/hp-hr))*(l lb/453.6 g)*(Btu/gal)*(1000 gal/Mgal) = Ib/Mgal
To convert from Ib/MMBtu to Ib/Mgal
Assumptions: You have the heating value (Btu/gal)
(lb/MMBtu)*(l MMBtu/1000000 Btu)*(Btu/gal)*(1000 gal/Mgal) = Ib/Mgal
To convert from Ib/MMBtu to g/hp-hr
Assumptions: You have the BSFC value (Btu/hp-hr)
(lb/MMBtu)*(l MMBtu/1000000 Btu)*(453.6 g/lb)*(Btu/hp-hr) = g/hp-hr
To convert % by volume to ppmv
% = parts per 100, therefore
(%/100)*(1000000/1000000) = (%*10000)/1000000 = %* 10000 ppmv
e.g., 5.1% CO = 51000 ppmv
To convert ug/s to g/hp-hr
Assumptions: Engine is running at full load (in hp)
(ug/s)*(l g/1000000 ug)*(3600 s/hr)*(l/hp) = g/hp-hr
For Dual Fuel Engines only, to convert from g/hp-hr to Ib/MMBtu
Assumptions: Average BSFC for dual fuel engines is 7163 Btu/hp-hr (see Reference
No.?)
(g/hp-hr)*(l/(7163 Btu/hp-hr))*(l lb/453.6 g)*(1000000 Btu/MMBtu) = Ib/MMBtu
To convert from ppm of a gas to Ibm/MMBtu:
Assumptions: You have the molecular weight of the gas (in Ib/lb-mol)
The concentration of the gas (in ppm)
You know the fuel F-factor (ft3/MMBtu)
You know the % O2 level
At STP conditions (293 K and 1 atm), 1 mole of gas occupies 385.3 ft3/lb-mol
(ppm/1000000)/(385.3ft3/lb-mol)*(lb/lb-mol)*(ft3/MMBtu)*(20.9/(20.9-%O2))= Ib/MMBtu
C-3
-------
To convert from g/hp-hr (english units) to g/kW-hr (metric units):
(g/hp-hr)*(1.341 hp-hr/kW-hr) = g/kW-hr
To convert from Ib/MMBtu (english units) to ng/J (metric units):
(lb/MMBtu)*(453.6 g/lb)*(l MMBtu/1000000 Btu)*(l Btu/1055 J)*(1000000000 ng/g) =
ng/J
To calculate CO2 emissions for diesel and dual fuel from weight % of carbon and BSFC
(g/hp-hr):
Assumptions: 87 wt% carbon in diesel
70 wt% carbon in natural gas
Fuel mixture = 5% diesel and 95% natural gas
Diesel heating value = 19300 Btu/lb
Natural gas heating value = 23900 Btu/lb
BSFC = 7000 Btu/hp-hr
For diesel fuel
(87 lbC/100 lbFuel)*(l lb-molC/12 lbC)*(l lb-molCO2/lb-molC)*
(44 lbCO2/lb-molCO2)*(lbFuel/19300 Btu)*(1000000 Btu/MMBtu) = 165 Ib/MMBtu
and
(165 lbCO2/MMBtu)*(l MMBtu/1000000 Btu)*(453.6 g/lb)*(7000 Btu/hp-hr) = 524 g/hp-
hr
For natural gas
(70 lbC/100 lbFuel)*(l lb-molC/12 lbC)*(l lb-molCO2/lb-molC)*
(44 lbCO2/lb-molCO2)*(lbFuel/23900 Btu)*(1000000 Btu/MMBtu) = 107.4 Ib/MMBtu
For dual fuel (using Ib CO2/MMBtu emissions from the above calculations):
(diesel emissions)*(diesel percentage) + (nat. gas emissions)*(nat. gas percentage)
(165 lb/MMBtu)*(5 Ib diesel/100 Ib fuel) + (107.4 lb/MMBtu)*(95 Ib nat. gas/100 Ib fuel)
= 110 Ib/MMBtu
and
(110 lbCO2/MMBtu)*(l MMBtu/1000000 Btu)*(453.6 g/lb)*(7000 Btu/hp-hr) = 350 g/hp-
hr
EMISSION-ff ACTORS 4/93
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APPENDIX D
MARKED-UP PREVIOUS AP-42 SECTION 3.4
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3-3
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