United States                  EPA-600/7-81-123a
               Environmental Protection
               Agency                     July 1981
oEPA        Research and
               Development
               COMBUSTION MODIFICATION CONTROLS

               FOR RESIDENTIAL AND COMMERCIAL

               HEATING SYSTEMS

               Volume I.  Environmental Assessment
                Prepared for
               Office of Air Quality Planning and Standards
                Prepared by

                industrial Environmental Research
                Laboratory
                Research Triangle Park NC 27711

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                  RESEARCH REPORTING SERIES


Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional  grouping was  consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

    1. Environmental Health Effects Research

    2. Environmental Protection Technology

    3. Ecological Research

    4. Environmental Monitoring

    5. Socioeconomic Environmental Studies

    6. Scientific and Technical Assessment Reports (STAR)

    7. Interagency Energy-Environment Research and Development

    8. "Special" Reports

    9. Miscellaneous Reports

This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded  under the 17-agency Federal  Energy/Environment Research  and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from  adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects;  assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
                        EPA REVIEW NOTICE


This report has been reviewed by the participating Federal Agencies, and approved
for  publication. Approval does not signify that the contents necessarily reflect
the  views and policies of the Government, nor does mention of trade names or
commercial products  constitute endorsement or  recommendation for. use.

This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.

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                                             EPA-600/7-81-123a
                                             July 1981
 COMBUSTION MODIFICATION CONTROLS FOR RESIDENTIAL
         AND COMMERCIAL HEATING SYSTEMS:
        VOLUME I.  ENVIRONMENTAL ASSESSMENT
                        By

    C. Castaldini, R. A.  Brown,  and K.  J.  Lim

                Acurex Corporation
         Energy & Environmental  Division
                 485 Clyde Avenue
         Mountain View, California  94042
               Contract 68-02-2160
             Program Element EHE 624A
                   Prepared for

        EPA Project Officer -- J. S. Bowen
     EPA Deputy Project Officer -- R. E. Hall
   Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
  Research Triangle Park, North Carolina  27711
       U.S. ENVIRONMENTAL PROTECTION AGENCY
        OFFICE OF RESEARCH AND DEVELOPMENT
              WASHINGTON, DC  20460

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                                 DISCLAIMER

       This Final Report was furnished to the U.S. Environmental
Protection Agency by Acurex Corporation, Energy & Environmental Division,
Mountain View, California  94042, in partial fulfillment of
Contract No. 68-02-2160.  The opinions, findings, and conclusions
expressed are those of the authors and not necessarily those of the
Environmental Protection Agency or of cooperating agencies.  Mention of
company or product names is not to be considered as an endorsement by the
Environmental Protection Agency.

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                                  PREFACE

       This is one in a series of five process engineering reports
documented in the "Environmental Assessment of Stationary Source NOV
                                                                   A
Combustion Modification Technologies" (NO  EA).  Specifically,  this
                                         A
report documents the environmental assessment of residential  and
commercial heating systems with primary emphasis on  NO  combustion
                                                      A
controls for residential warm air furnaces.  The NOV EA,  a 36-month
                                                   A
program which began in July 1976, is sponsored by the Combustion Research
Branch of the Industrial and Environmental Research  Laboratory  of EPA
(IERL-RTP).  The program has two main objectives:  (1) to identify the
multimedia environmental impact of stationary combustion  sources and  NO
                                                                       A
combustion modification controls applied to these sources, and  (2) to
identify the most cost-effective, environmentally sound NO  combustion
                                                          A
modification controls for attaining and maintaining  current and projected
N02 air quality standards to the year 2000.
       The NO  EA is assessing the following combination  of process
             A
parameters and environmental impacts:
       •   Major fuel combustion stationary NOX sources:   utility
           boilers, industrial boilers, gas turbines, internal  combustion
           (1C) engines, and commmercial and residential  warm air
           furnaces.  Other sources (including mobile and noncombustion)
           will be considered only to the extent that they are  needed to
           determine the NO  contribution from stationary combustion
                           A
           sources.
       •   Conventional and alternate gaseous, liquid and solid fuels
       •   Combustion modification N0x controls with potential  for
           implementation to the year 2000; other controls (flue gas
           cleaning, mobile controls) will be considered  only to estimate
           the future need for combustion modifications

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       t   Source effluent streams potentially affected by NO  controls
                                                             /\
       •   Primary and secondary gaseous, liquid and solid pollutants
           potentially affected by NOX controls
       •   Pollutant impacts on human health and terrestrial or aquatic
           ecology
       To achieve the objectives discussed above, the NOX EA program
approach is structured as shown schematically in Figure P-l.  The two
major tasks are:  Environmental Assessment and Process Engineering
(Task 85), and Systems Analysis (Task C).  Each of these tasks is designed
to achieve one of the overall objectives of the NO  EA program cited
                                                  /\
earlier.  In Task B5, of which this report is a part, the environmental,
economic, and operational impacts of specific source/control combinations
are evaluated.  On the basis of this assessment, the incremental
multimedia impacts from the use of combustion modification NO  controls
                                                             /\
will be identified and ranked.  Systems analysis in turn uses the results
of Task B5 to identify and rank the most effective source/control
combinations to comply, on a local  basis, with the current N0? air
quality standards and projected N02 related  standards.
       As shown in Figure P-l, the key tasks supporting Tasks B5  and C are
Baseline Emissions Characterization (Task Bl), Evaluation  of Emission
Impacts and Standards (Task B2), and Experimental Testing (Task B3).  The
arrows in Figure P-l  show the sequence of subtasks and the major
interactions among the tasks.  The oval symbols identify the major outputs
of each task.  The subtasks under each main  task are shown on the figure
from the top to the bottom of the page in roughly the same order  in  which
they will be carried  out.
       As indicated above, this report is a  part of the Process
Engineering and Environmental Assessment Task.  The goal of this  task is
to generate process evaluations and environmental assessments for specific
source/control combinations.  These studies  will be done in  order of
descending priority.   In the first year of the N0y EA,  all the sources
                                                 /\
and controls involved in current and planned NOX control implementation
programs were investigated.  The "Preliminary Environmental  Assessment of
Combustion  Modification Techniques" (Reference P-l) documented this  effort
and established a priority ranking based on  source emission  impact and
                                     iv

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                                                                   NOV  EA  approach.
                                                                       A

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potential for effective NO  control,  to  be used  in  the  current  ongoing
                          ^
detailed evaluation.
       This report presents the assessment of  combustion modification
NOX controls for the  last source category  to be  treated, residential  and
commercial  heating systems.  Other  environmental  assessment  reports
documented  are:
       •   Environmental  Assessment of Utility Boiler Combustion
           Modification  NO  Controls  (Reference  P-2)
                          /\
       •   Environmental  Assessment of Industrial Boiler Combustion
           Modification  NOX Controls  (Reference  P-3)
       •   Environmental  Assessment of Combustion Modification  Controls
           for Stationary Gas Turbines (Reference P-4)
       •   Environmental  Assessment of Combustion Modification  Controls
           for Stationary Internal  Combustion  Engines (Reference P-5)

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                           REFERENCES FOR PREFACE
P-l.   Mason, H. B., et al., "Preliminary Environmental Assessment of
       Combustion Modification Techniques:  Volume II.  Technical
       Results," EPA-600/7-77-119b, NTIS-PB 276 681/AS, October 1977.

P-2.   Lim, K. J., et al., "Environmental Assessment of Utility Boiler
       Combustion Mocfif i cat ion NOX Controls:  Volume 1.  Technical
       Results; Volume II:  Appendices," EPA-600/7-80-075a,b, April 1980.

P-3.   Lim, K. J., jit al., "Industrial Boiler Combustion Modification
       NOX Controls:  "Volume I.  Environmental Assessment,"
       EPA-600/7-81-126a, July 1981.

P-4.   Larkin, R., et al., "Combustion Modification Controls for
       Stationary Gas Turbines:  Volume I.  Environmental Assessment,"
       EPA-600/7/81-122a, July 1981.

P-5.   Lips,  H.  I., et al., "Environmental Assessment of Combustion
       Modification Controls for Stationary Internal Combustion Engines,"
       EPA-600/7-81-127, July 1981.
                                     VII

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                             TABLE OF CONTENTS

Section                                                                Page

           Preface	     iii

   1       EXECUTIVE SUMMARY	     1-1

           1.1  Overview of Residential and Commercial
                Heating Systems  	     1-1
           1.2  Emissions and Fuels	     1-3
           1.3  Status of Environmental Protection Alternatives. .     1-4
           1.4  Environmental and Cost Impacts	     1-11
           1.5  Data Needs and Recommendations	     1-17

   2       INTRODUCTION	     2-1

           2.1  Background	     2-1
           2.2  Role of Residential and Commercial Heating
                Systems	     2-2
           2.3  Objective of this Report	     2-4
           2.4  Organization of this Report	     2-5

   3       SOURCE CHARACTERIZATION 	     3-1

           3.1  Equipment Types	     3-1

           3.1.1  Residential Units	     3-3
           3.1.2  Commercial Units 	     3-3

           3.2  Furnace Design Practice	     3-10

           3.2.1  Residential Units	     3-10
           3.2.2  Commercial Systems 	     3-34

           3.3  Areas of Environmental Concern 	     3-40

           3.3.1  Stack Emissions	     3-42
           3.3.2  Leakage of Combustion Products  	     3-42
           3.3.3  Solid Waste Streams	     3-43

   4       CHARACTERIZATION OF FUELS, PRODUCTS AND AIR
           EMISSIONS	     4-1

           4.1  Summary of Sampling and Analytical Activities   .  .     4-1
           4.2  Fuels	     4-6

           4.2.1  Gaseous Fuels	     4-6
           4.2.2  Liquid Fuels	     4-7
           4.2.3  Solid Fuels	     4-12

           4.3  Product Characterization 	     4-16
           4.4  NOX Formation	     4-17

                                     ix

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                       TABLE OF CONTENTS (Continued)

Section

           4.4.1  Thermal NOX Formation	     4-17
           4.4.2  Fuel NOX Formation	     4-17

           4.5  Emission Characterization  	     4-18

           4.5.1  Nitric Oxide Emissions 	     4-23
           4.5.2  Carbon Monoxide and Hydrocarbon Emissions  .  .  .     4-23
           4.5.3  Smoke and Particulate Emissions  	     4-24
           4.5.4  Emission Factors and Emission Inventory  ....     4-24

   5       PERFORMANCE AND COST OF CONTROLS	     5-1

           5.1  Emission Control Alternatives for Gas-Fired
                Residential Systems  	     5-1

           5.1.1  Nitric Oxide Control 	     5-2
           5.1.2  Carbon Monoxide and Unburned Hydrocarbon
                  Control	     5-12
           5.1.3  Cost and Energy Impact of Controls	     5-14

           5.2  Emission Control Alternatives for Oil-Fired
                Residential Systems  	     5-15

           5.2.1  Nitric Oxide Control 	     5-16
           5.2.2  Carbon Monoxide and Unburned Hydrocarbon
                  Control	     5-28
           5.2.3  Smoke and Particulate Control  	     5-34
           5.2.4  Cost and Energy Impact of Controls	     5-37

           5.3  Emission Control Alternatives for Solid
                Fuel-Fired Residential Systems 	     5-39
           5.4  Surmiary of Most Effective Control Alternatives
                for Residential Systems  	     5-41

           5.4.1  Gas-Fired Systems  	     5-41
           5.4.2  Oil-Fired Systems  	     5-43

           5.5  Emission Control Alternatives for Commercial
                Systems	     5.47

           5.5.1  Commercial Heaters 	     5.47
           5.5.2  Commercial Boilers 	     5_48

   6       ENVIRONMENTAL ASSESSMENT  	     6-1

           6.1  Environmental Impact Analysis  	     6-2
           6.2  Source Analysis Model Evaluation 	     6-4
           6.3  Environmental Impacts of NOX Controls
                on Criteria Pollutants 	     6-8

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                       TABLE OF CONTENTS (Concluded)

Section                                                                Page

           6.4  Operational and Cost Impacts of Controls	     6-10
           6.5  Data Base Evaluation and Needs	     6-13

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                           LIST OF ILLUSTRATIONS
Figure                                                                Page
 P-l       NOX EA Approach	      v
 2-1       Distribution of Stationary Anthropogenic NOX
           Emissions for the Year 1977 (Controlled NOX
           Levels)	    2-3
 3-1       Distribution of Residential and Commercial Heating
           Systems	    3-2
 3-2       Gas-Fired Forced Air Furnaces  	    3-13
 3-3       Gas-Fired Forced Air Downflow  Furnace and Details of
           Components	    3-15
 3-4       Oil-Fired Central Air Furnaces  	    3-19
 3-5       Typical High Pressure Atomizing Gun Oil Burners ....    3-21
 3-6       ABC Mite Burner with Flame Retention Head	    3-25
 3-7       Gas-Fired Hydronic Boiler 	    3-27
 3-8       Oil-Fired Hydronic System 	    3-31
 3-9       Residential Heater Stoker Assembly  	    3-33
 3-10      Direct Gas-Fired Duct Heater and Line Burner
           Assembly	    3-36
 3-11      Simplified Diagram of a Watertube Boiler  	    3-38
 3-12      Simplified Diagram of a Firetube Boiler 	    3-38
 3-13      Exposed-tube Vertical Boiler  	    3-40
 4-1       Effect of API Gravity on Particulate Emissions  ....    4-11
 4-2       Effect of Free Swelling Index  on Boiler Particulate
           Emissions	    4-14
 4-3       Effect of Coal Volatile Content on Boiler
           Particulate Emissions 	    4-15
 4-4       Contribution of Nitrogen in Fuel Oil to Total NOX
           Emissions from Commercial Boilers 	    4-18

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                    LIST OF ILLUSTRATIONS (Concluded)

Figure                                                                Page

 4-5       General Trend of Smoke, Gaseous Emissions, and
           Efficiency Versus Stoichiometric Ratio for a
           Residential Oil Burner  	    4-19

 4-6       Gaseous Emissions Characteristic for a Typical
           Commercial Boiler as Influenced by Combustion Air
           Setting	    4-19

 4-7       Temperature Rise Across an Oil-fired Warm Air
           Furnace Heat Exchanger During a Typical Cycle 	    4-21

 4-8       Characteristic Emissions of Oil Burners During
           One Complete Cycle	    4-22

 5-1       General Arrangements of Screens for Gas-Fired
           Residential Burners 	    5-3

 5-2       Effect on NOX Emissions of Placing a Screen in the
           Flame of a Meker Type Burner	    5-4

 5-3       Amana Heat Transfer Module (HTM)  	    5-7

 5-4       Schematic of the Bratko Burner	    5-9

 5-5       Schematic Operating Cycle of a Pulse Combustion
           Device	    5-11

 5-6       Effect of Air Adjustment on Gaseous Emissions for a
           Typical Atmospheric Gas Burner  	    5-13

 5-7       1 ml/s (gph) Optimum Low-Emission Residential
           Oil Burner	    5-19

 5-8       Comparative NO Emissions for the Controlled Mixing
           EPA/Rocketdyne Burner Heat as a Retrofit Device in
           Two Warm-Air Furnaces 	    5-22

 5-9       EPA Low-Emission Integrated Furnace Components  ....    5-23

 5-10      Schematic  Illustration of the Blueray Head Assembly .  .    5-26

 5-11      Schematic of the M.A.N. Residential Oil-Fired
           Rocketburner   	    5-28

 5-12      Distribution of Smoke Emission for Residential
           Units	    5-35

 5-13      Schematic of the Cross-Feed Combustion Design for
           Coal-Fired Residential Furnaces 	    5-40
                                   xm

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                              LIST OF TABLES

Table

 1-1       Estimated 1977 Air Pollutant Emissions from Stationary
           Fuel Combustion Sources with Heat Input Capacity Less
           Than 2.9 MW (10 x 106 Btu/hr)	     1-5

 1-2       Performance Sunmary of Low-N0x Control Equipment for
           Natural Gas-Fired Residential Heaters 	     1-7

 1-3       Performance Surrrnary of Low-N0x Control Equipment
           for Distillate Oil-Fired Residential  Heaters	     1-8

 1-4       Performance Sumnary of Controls for Reduction of
           Seasonal Combustible, Smoke and Particulate
           Emissions from Oil-Fired Residential  Heaters  	     1-12

 1-5       Flue Gas Discharge Severities Greater Than 0.1 for the
           Blueray Furnace and Conventional Oil-Fired Heaters  . .     1-14

 1-6       Cost Impact of NOX Control Alternatives	     1-16

 3-1       Population and Ranking of Domestic Heating Systems
           By Type (1976) -- 1000 Units	     3-4

 3-2       Regional Distribution of Residential  Heating
           Equipment by Fuel (1976) ~ 1000 Units	     3-5

 3-3       Regional Distribution of Residential  Heating
           Equipment by Equipment Type (1976) — 1000 Units  ...     3-6

 3-4       Population of Boilers with Less Than 2.9  MW
           (10 x 106 Btu/hr) Heat Input Capacity in  Use in the
           Industrial Sector -- 1977 Number of Units (Installed
           Capacity MW)  	     3-8

 3-5       Population of Boilers with Less Than 2.9  MW
           (10 x 106 Btu/hr) Heat Input Capacity in  Use in the
           Industrial Sector — 1977 Number of Units (Installed
           Capacity MW).  .	     3-9

 3-6       Summary of Installed Capacities of Commercial and
           Industrial Steam and Hot Water Units with Heat Input
           Less Than 2.9 MW (10 x 106 Btu/hr) -- MW  (Percent)   .  .     3-11

 3-7       Typical Operating Conditions for a Warm Air
           Gas-Fired Furnace: 29.3 kW (100,000 Btu/hr) 	     3-18

 3-8       Typical Operating Conditions for Oil-Fired Central
           Air Systems: 29.3 kW (100,000 Btu/hr)	     3-24

 3-9       Typical Operating Conditions for Oil- and Gas-Fired
           Hot Water with 29.3 kW (100,000 Btu/hr) Heat Input.  .  .     3-30

                                    xiv

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                         LIST OF TABLES (Concluded)

Table                                                                  Page

 3-10      Emission Streams from Residential and Commercial
           Units	     3-41

 4-1       Summary of Major Sampling and Analytical Activities
           on Residential and Commercial Heating Systems 	     4-2

 4-2       Fuel Oil Designations and Typical Characteristics . . .     4-8

 4-3       Estimated 1977 Air Pollutant Emissions of Industrial
           Commercial and Residential Fuel Combustion Sources
           With Heat Input Capacity Less Than 2.9 MW
           (10 x 106 Btu/hr)	     4-25

 5-1       Effect  on CO  and NOX Emission of Placing Radiant
           Screen  in Burner Flame  	     5-3

 5-2       Effect  of a Radiating Screen From a Furnace Operated on
           Cleveland Natural  and Algerian LNG	     5-5

 5-3       Effect  on Mean Emission of Identifying and Replacing
           Residential Units  in Poor Condition and Tuning  ....     5-32

 5-4       Performance Surmiary of Low NOX Control Equipment for
           Natural Gas-Fired  Residential Heaters 	     5-42

 5-5       Performance Surmiary of Low-N0x Control Equipment for
           Distillate Oil-Fired Residential Heaters  	     5-44

 5-6       Performance Sumnary of Controls for Reduction of
           Seasonal Combustible, Smoke, and Particulate Emissions
           From Oil-Fired Residential Heaters  	     5-46

 5-7       Combustion Modification NOX Controls for Oil- and
           Gas-Fired Industrial Boilers  	     5-49

 5-8       Combustion Modification NOX Controls for Stoker
           Coal-Fired Industrial Boilers 	     5-51

 6-1       Criteria Trace Elements and Organic Emissions from
           Conventional  and Low-N0x Furnaces 	     6-3

 6-2       Flue Gas Discharge Severities Greater than 0.1 for  the
           Blueray Furnace and Conventional Oil-Fired Heaters   .  .     6-6

 6-3       Environmental Impact of Most Effective NOX Control
           Alternatives  on Residential Space Heaters 	     6-9

 6-4       Cost Impact of NOX Control Alternatives	     6-12
                                     xv

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                                 SECTION  1
                             EXECUTIVE SUMMARY

       With more NO  controls being  implemented  in the field and
                   A
expanded control development anticipated  for the future, there is
currently a need to:   (1) ensure that the current and emerging control
techniques are  technically  and environmentally sound and compatible with
efficient and economical operation of systems to which they are applied,
and  (2) ensure  that the scope and timing  of new control development
programs are adequate  to allow stationary sources of NO  to comply with
                                                       A
potential air quality  standards.  The residential and commercial  heating
system environmental assessment helps to  address these needs by evaluating
the  operational, economic and environmental impacts from applying
combustion modification NO  controls.
                          A
       Residential warm air furnaces, the major source category dealt with
in this report, are the fifth largest contributors of man-made NO
                                                                 A
emissions from  stationary sources in the  U.S. -- constituting about
2 percent of annual nationwide emissions.  It is projected that their
contribution will remain significant through the year 2000
(Reference 1-1).  Given this background and their potential for NO
                                                                  A
control, residential and commercial heating systems were specified as a
major category  to be studied under the N0x EA program.
1.1    OVERVIEW OF RESIDENTIAL AND COMMERCIAL HEATING SYSTEMS
       The major domestic fuel combustion sources are central warm air
furnaces, room or direct heaters, residential hot water heaters,  and steam
and  hot water hydronic boilers for space  and water heating.  Minor sources
include stoves  and fireplaces; these consume a relatively  insignificant
quantity of fuel compared to other space  heating equipment.
       The primary fuels for residential  heating are natural gas and
distillate oils (no. 1, kerosene, or no.  2 distillate).  These fuels

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combined account for nearly 90 percent of all fuel burned for domestic
heating.  Liquified petroleum gas, LPG (butane or propane), coal and wood
are also used, although in relatively small quantities.  In 1976 LPG-fired
equipment account for about 6 percent of domestic heating equipment while
coal- and wood-fired units account for only 2 percent of the total
equipment population.  Built-in electric residential heating systems have
become increasingly popular as domestic supply of clean fuels dwindles and
fuel costs increase.  Electrical  heaters in 1976 accounted for nearly
14 percent of residential  heating equipment.
       The primary fuels and equipment used for domestic heating show
significant regional variation.  For example, the Northeast regions depend
primarily on oil-fired steam or hot water units while in all other
regions, natural gas-fired central warm air furnaces are the primary
equipment type for domestic space heating.
       Combustion equipment in most residential heating systems is
similar.  For natural gas-fired equipment the single port upshot or the
tubular multiport burners  are the most common burner types.  Natural gas-
fired warm air furnaces, room heaters, or hot water heaters often use a
pilot flame to ignite the  burner  automatically.  Distillate oil-fired
residential heating systems generally use high pressure atomizing gun type
burners.  Nearly all new oil-fired burners  use the flame retention burner
head which promotes more efficient combustion.
       Commercial heating  systems can be divided into three general
categories:  warm air unit heaters or space heaters, warm air furnaces or
duct heaters, and hot water or steam systems.  The combustion system of
commercial warm air unit or space heaters and duct heaters is generally
similar to residential equipment, although  there are a few unique
gas-fired designs.  Warm air units and duct heaters are either direct or
indirect fired.  Direct fired heaters use only clean gaseous fuels.  These
units exhaust the combustion products directly into the heated space.
Indirect fired heaters use either gas or oil fuels and are vented to the
outdoors.  These units, except for their larger capacity, are generally
similar to residential central warm air furnaces.  Information on
equipment population and emissions from commercial space heaters is
limited.
                                    1-2

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       Hot water and steam systems in the commercial size capacity, here
defined in the range of 0.12 to 2.9 MW ((0.4 to 10) x 106 Btu/hr) heat
input capacity, include cast iron hydronic boilers  and small firetube and
watertube boilers used in both the commercial and  industrial sectors.
Cast iron hydronic boilers are also used in residential as well as
commercial applications.  These units, which are common in the
Northeastern and Northcentral regions of the U.S.,  are primarily either
gas- or distillate oil-fired.  Firetube and small watertube boilers used
for heating of large commercial plants and buildings are similar to the
smaller industrial boilers used to generate process steam.  These boilers
are generally fired with gas, oil or  less frequently stoker coal, and
account for about 25 percent of the installed capacity of steam and hot
water boilers with heat input capacity less then 2.9 MW (10 x 106
Btu/hr).
1.2    EMISSIONS AND FUELS
       Because natural gas and distillate oil are the principal fuels used
in domestic and commercial heating systems, air pollutant emissions
represent the primary waste stream of environmental concern.  Coal- and
wood-fired furnaces and stoves, however, also produce solid ash waste
streams.  Although increasing in popularity due to  the scarcity and high
cost of clean fuels, residential wood- and coal-fired systems account for
only 2 percent of all domestic heaters.  Thus nationally, solid waste
streams from residential heating pose only a minor  environmental concern
but are potentially significant when considered on  a local or regional
basis.  Commercial coal-fired watertube and firetube stokers are also the
source of solid waste streams.  These units, which  account for about
15 percent of the firetube and watertube population, could increase in
popularity with economic and political incentives for increased use of
domestic coal.
       Flue gas stream composition from residential heating equipment
depends highly on the type of fuel burned, burner type, combustor
geometry, combustor material and operating characteristics.  Natural gas-
fired equipment emits NO , carbon monoxide (CO) and unburned
                        /\
hydrocarbons (UHC).   When distillate oil is used, particulate (smoke) and
small quantities of SOX are also emitted.  NOX emissions are generally
                                    1-3

-------
highest and CO, UHC and smoke are lowest when the heater operates at
design (tuned) and steady state conditions.  S02 emissions are a
function of the sulfur content of the oil.  SO,, control is primarily
achieved by using low sulfur oil.
       NO  is one of the primary pollutants of concern with residential
         /\
gas- and oil-fired heaters.  It is emitted in significant quantities,  is
deleterious to human respiratory functions and acts as a key precursor to
photochemical smog.  Carbon monoxide, UHC and smoke made up of carbon
particles or soot are products of incomplete combustion.  These pollutants
are emitted in the largest quantity during ignition, and warm up and shut
off periods of a residential furnace heating cycle.  Because domestic
heaters operate in a cyclic mode combustible emissions due to on-off
transients account for the majority of the total yearly emissions.
Control techniques for reducing combustible emissions often concentrate on
reducing the heater cycling frequency.
       Table 1-1 summarizes 1977 emissions for stationary combustion
sources with heat input less than 2.9 MW (10 x 106 Btu/hr).  These
sources include primarily residential and commercial heating systems as
well as small industrial boilers (Reference 1-2).  Residential and
commercial heating systems contribute 56 and 28 percent respectively of
the total NO  from these sources.  These emissions are seasonal with
            A
nearly all the total annual output occurring in the cold winter months;
during that period the impact of residential and commercial heating on
ground level ambient N02 concentration in urban areas can be significant
(References 1-3, 1-4).
1.3    STATUS OF ENVIRONMENTAL PROTECTION ALTERNATIVES
       Emission control technology for residential and commercial
equipment is typically adapted to the specific fuel and burner type.
Because NOX emissions from either gas or distillate oil combustion are
primarily due to thermal NOX, control techniques are aimed at
controlling temperature or oxygen availability in the  high temperature
flame region.  Tables 1-2 and 1-3 summarize NOV control alternatives for
                                              /\
residential heaters firing natural gas and distillate oil respectively.
These controls have been developed primarily for warm air furnaces;
however, the advanced burner and combustor redesign technology presented
                                    1-4

-------
              TABLE  1-1.   ESTIMATED 1977 AIR  POLLUTANT  EMISSIONS  FROM  STATIONARY
                            FUEL  COMBUSTION SOURCES  WITH  HEAT  CAPACITY LESS  THAN
                            2.9  MW  (10 x  106 Btu/hr)a
Sector
Residential":
Residential
and Commercial
Equipment
Warm air central
furnaces
Warm air space
heaters
Miscellaneous
combustion
Steam and hot
water heaters
Fuel
Natural gas
Distillate
oil
Natural gas
Distillate
oil
Natural gas
Distillate
011
Natural gas
Distillate
oil
Residual oil
Coal
Total Capacity
MW (106 Btu/hr)
--
-
--
-
—
-
--
--
--
--
Fuelb
Consumption
EJ (Quads)
1.876C
(1.979)
1.354C
(1.428)
0.57C
(0.60)
0.42C
(0.44)
1.524C
(1.608)
0.926C
(0.977)
2. 1C
'(2.2)
1.4C
(1.5)
O.llc
(0.12)
0.043C
(0.045)
Air Pollutant Emissions Gg (103 tons)
NOX
65.7
(72.5)
33.8
(37.3)
19.9
(21.9)
10.5
(11.6)
53.3
(58.8)
27.4
(30.2)
82.8
(91.3)
77.9
(85.9)
17.5
(19.3)
7.1
(7.8)
CO
19.0
(20.9)
33.8
(37.3)
5.7
(6.3)
10.5
(11.6)
15.2
(16.8)
27.4
(30.2)
17.8
(19.6)
41.7
(46.0)
1.64
(1.81)
7.53
(8.30)
HC
6.40
(7.10)
6.40
(7.06)
1.94
(2.14)
1.97
(2.17)
5.20
(5.73)
5.15
(5.68)
4.76
(5.25)
13.4
(14.8)
2.74
(3.02)
2.12
(2.34)
Particulates
7.50
(8.27)
10.3
(11.4)
2.30
(2.54)
3.20
(3.53)
6.10
(6.73)
8.33
(9.19)
16.6
(18.3)
10.6
(11.7)
9.09
(10.0)
150.2
(165.6)
SOX
0.49
(0.54)
146
(161)
0.15
(0.17)
45.4
(50.1)
0.40
(0.44)
118.4
(130.6)
0.62
0.68
150.2
(165.6)
52.6
(58.0)
30.7
(33.8)
aBased on data from References 1-1, 1-2,  and 1-5.
bEJ = 1018 Joules = 0.948 Quads = 0.948 x 1015 Btu
"-Fuel consumption for residential units was obtained from Department of Energy  (Reference 1-5).

-------
TABLE 1-1.  (Concluded)
Sector
Commercial
and Industrial
TOTAL
Equipment
Cast iron
boilers
Watertube
boilers
Firetube
boilers
AH equipment
Fuel
Natural gas
Distillate
oil
Residual oil
Coal
Natural gas
Distillate
oil
Residual oil
Coal
Natural gas
Distillate
oil
Residual
oil
Coal
All fuels
Total Capacity
W (106 Btu/hr)
143,520
(489,495)
33,730
(115,041)
53,790
(183,456)
31,590
(107,742)
5,770
(19,679)
4,490
(15,313)
5,240
(17.872)
1,900
(6,480)
79,090
(269,748)
31,530
(107,538)
48,200
(164,393)
14,420
(49,181)
--
Fuelb
Consumption
EJ (Quads)
1.8
(1.9)
0.35
(0.37.)
0.47
(0.50)
0.097
(1.0)
0.053
(0.056)
0.021
(0.023)
0.015
(0.016)
0.012
(0.013)
1.358
(1.433)
0.37
(0.39)
0.354
(0.374)
0.11
(0.116)
15.22
(16.97)
Air Pollutant Emissions Gg (10-' tons)
NOX
91.7
(101.1)
23.7
(26.1)
84.6
(93.3)
14.6
(16.1)
3.16
(3.5)
1.18
(1.3)
2.38
(2.6)
3.0
(3.3)
31.0
(34.2)
12.8
(14.1)
30.7
(33.9)
14.1
(15.6)
708.8
(781.6)
CO
35.3
(38.9)
0.56
(0.61)
0.66
(0.73)
21.3
(23.5)
1.06
(1.17)
0.06
(0.07)
0.02
(0.02)
0.91
(1.00)
15.2
(16.8)
0.34
(0.38)
0.29
(0.32)
5.40
(5.95)
261.4
(288.3)
HC
4.06
(4.48)
3.34
(3.68)
11.8
(13.8)
5.53
(6.10)
0.18
(0.20)
0.01
(0.01)
0.07
(0.08)
0.19
(0.21)
1.75
(1.93)
2.05
(2.26)
5.12
(5.65)
3.40
(3.75)
87.6
(96.6)
Particulates
6.88
(7.59)
4.18
(4.61)
13.2
(14.6)
314.3
(346.6)
0.05
(0.05)
0.18
(0.20)
0.42
(0.46)
23.5
(25.9)
3.02
(3.33)
2.57
(2.83)
5.73
(6.32)
130.0
(143.4)
728.3
(803.1)
*>x
0.53
(0.58)
37.6
(41.5)
225.6
(248.8)
110.6
(122.0)
0.02
(0.02)
3.27
(3.61)
6.70
(7.39)
16.0
(17.6)
0.23
(0.25)
18.7
(20.6)
92.1
(101.61)
91.8
(101.2)
1,148.1
(1,266.0)

-------
                 TABLE  1-2.   PERFORMANCE  SUMMARY OF  LOW-NOX CONTROL  EQUIPMENT  FOR
                               NATURAL  GAS-FIRED  RESIDENTIAL HEATERS
Control
Conventional
Units
Radiant Screens
Secondary Air
Baffles
Surface Combus-
tion Burner
Amana (HTM)
Modulating
Furnace
Pulse
Comb us tor
Catalytic
Comb us tor
Average
Operating
Excess A1r
(percent)
40-120
40-120
60-80
10
NA
NA
NA
NA
Cyclic Pollutant Emissions
nq/J Heat Input
NV
28-45
15-18
22
7.5
7.7
25
10-20
<5
CO
8.6-25
6.4
14
5.5-9.6
26
NA
NA
NA
UHCb
3.3-33
NA
NA
NA
NA
NA
NA
NA
Steady State
Efficiency
(percent)
70
75
NA
NA
85
75
95
90
Cycle
Efficiency
(percent)
60-65
70
NA
NA
80
70
95
85
1978
Installed
Control
Cost
c
NA
NA
$100-$200
$100-$300
over
conventional
furnace
$50-$250
over con-
ventional
furnace
$300 -$600
$100-$250
Comments
Emission factors from References 1-6
and 1-7. Costs Include Installation
Emissions of CO and HC can Increase
significantly 1f screen 1s not placed
properly or deforms
Requires careful installation. Best
suited for single port upshot burners
Not commercially available. Still
under development
Commercially available design. Spark
Ignited thus requires no pilot
Furnace is essential ly derated. Thus
it requires longer operation to deliver
a given heat load
Currently being investigated by AGAL.
Efficiencies correspond to condensing
systems.
Still at the R&D stage. Efficiencies
correspond to condensing systems.
«Sum of NO + NO? reported as NO?
bl)nburned hydrocarbons calculated as methane (CH4)
cTyp1cal costs of uncontrolled unit $500-$800
 NA « not available

-------
                             TABLE  1-3.   PERFORMANCE  SUMMARY  OF  LOW-NOX  CONTROL  EQUIPMENT
                                            FOR DISTILLATE OIL-FIRED RESIDENTIAL HEATERS





Control
Conventional
Units






Flame Reten-
tion Burner
Head

Controlled
Mixing
Burner Head
by EPA/
Rocketdyne
Integrated
Furnace Sys-
tem by EPA/
Rocketdyne



Bluer ay
"blue flame"
Burner/Furnace
System
M.A.N.
Burner





Average
Operating
Excess air
(percent)
50-85







20-40



10-50




20-30






20



10-15




Cyclic Pollutant Emissions
ng/J Heat Input


Smoke
NOX CO UHCb Number Particulate
37-85 15-30 3.0-9.0 3.2 7.6-30







26-88 11-22 0.2-1.8 2.0 NA



34 13 0.7-1.0 <1.0 NA




19 20 1.2 <1.0 NA






10 4.5-7.5 1.5-2.5 zero NA



10-25 <30 NA <1.0 NA







Steady State
Efficiency
(percent)
75







80-83
also depends
on heat
exchanger
80
also depends
on heat
exchanger

84






84



85







Cycle
Efficiency
(percent)
65-70







NA



NA




74






74



NA






1978
Installed
Control
Cost
c







$52d



$43d




$250 over
conven-
tional
furnace



$100 over
conven-
tional
furnace
NA









Comments
Range in NOX emissions is
for residential systems not
equipped with flame reten-
tion burners (References 1-4
and 1-8). Emissions for
other pollutants are aver-
ages reported in
References 1-7 and 1-8.
If a new burner is needed as
well as a burner head, the
total cost would be $385.

Cost of mass produced burner
head only about $1.50. Com-
bustible emissions are
relatively low because hot
firebox was used.
Uses optimized burner head.
For new furnace installation
only. Combustible emissions
are higher than with burner
head because of quenching in
in air cooled firebox.
Recent cost estimate.
New installation only.
Furnace is commercially
available. Recent cost
estimate.
Both for -retrofit or new
installations. Not yet
commercially available 1n
U.S. Commercialization
expected in 1980.
 I
00
        aSum of NO and NOg reported as NO?
        bUnburned hydrocarbons calculated as Methane
        cTyp1cal costs of uncontrolled unit $650-$!,000
        ^Original costs reported for years other than 1978 were corrected for inflation
          using Gross National Product (SNP) implicit price inflators (Reference 1-9)
        NA — Not available

-------
in these tables could possibly be applied also to other domestic heating
equipment as well as some larger commercial installations.
       For residential gas-fired heaters, the American Gas Association
Laboratories (AGAL) developed radiant screens and secondary air baffles
capable of average NO  reductions of 58 and 20 percent respectively.
                     /\
However, these controls may find little application because of
installation and performance problems highlighted by the Gas Appliance
Manufacturer Association (GAMA).  Two advanced NO  control alternatives
                                                 A
are the Bratko surface combustor and the Amana Heat Transfer Module
(HTM).  In these concepts, the radiation from the combustion zone
maintains a lower temperature of the combustion products and thus lower
NOX production while maintaining good efficiency and low CO levels.
NO  emissions from both the Bratko and Amana burners are approximately
  A
80 percent below levels of conventional warm air furnaces.  Between the
two, the Amana is the only commercially available unit and its cost to the
consumer is generally $100 to $300 above that of a conventional furnace.
       The modulating furnace system produces a cooler flame by altering
the burner firing rate to respond to heating costs instead of cycling on
and off.  N0x reductions of about 40 percent have been reported.  AGAL
is currently investigating pulse combustion for residential heating using
a condensing exhaust gas system.  Preliminary NO  emissions have been
                                                A
reported in the  19 to 20 ng/J range.  Commercialization of the pulse
combustor residential heating system is expected in 1981.  Catalysts
promoting combustion of fuel at  low temperature offer potential for very
low NO  emissions while maintaining good combustion efficiency.
      A
Research groups  and trade organizations are investigating the commercial
feasibility of catalytic combustion for residential warm air and hot water
systems burning  natural gas.  Performance and emission data for these
systems have not yet been published; however, N0x emissions are expected
to be very low.
       Residential oil-fired heaters are forced draft fired and therefore
more readily modified for reduced emissions and increased efficiencies
than natural draft gas-fired heaters.  Early work involved the development
of the flame retention oil burner.  These units produce lower CO, UHC and
smoke emissions  and operate on excess air lower than previous conventional
                                     1-9

-------
oil burner designs.  In some particular designs the flame retention
devices also lower NO  emissions by 20 to 40 percent.  Furthermore, they
                     /\
stay tuned longer and thus maintain low combustible emission levels
(Reference 1-6).  These units are now the primary residential oil burners
sold.
       As part of their combustion research program, the EPA has supported
low-NO  high efficiency residential burner development since 1971.
      A
Under one program, Rocketdyne developed a controlled mixing burner head
for retrofit and new applications on domestic heaters.  It was estimated
that widespread application of the relatively inexpensive burner head
device would be effective in reducing NO  by 20 percent and increase
efficiency by 5 percent on the average for each retrofitted furnace.
Recently the burner has been integrated with an "optimum"* low emission
high efficiency warm air furnace.  NOV emissions have been reduced by 65
                                     A
to 70 percent and steady state efficiencies have been increased by
10 percent over those of conventional  designs.  The EPA program emphasized
the necessity to match the firebox, burner and heat exchanger design to
achieve low-NOx emissions while also maintaining low levels of CO, UHC
and smoke.
       Both the Blueray "blue flame" and the M.A.N. burners use
aerodynamic flue gas recirculation to achieve a blue flame with distillate
fuel oil.  These burners thus achieve reduced flame temperature, dilution
of the oxygen concentration in the near-burner zone and rapid vaporization
of the fuel prior to ignition.  These conditions result in low NO
                                                                 A
emissions on the order of 15 to 40 ppm corrected at zero percent excess
air, representing NOX reductions of 50 to 80 percent.  Theoretically,
these burner concepts could be scaled up to larger commercial sizes.  The
Blueray furnace system is currently the only commercially available low-
NO  system in the U.S.  for oil-fired residential use.
  A
       Control  techniques aimed at reducing seasonal pollutant emissions
from residential heating systems through improved fuel  economy and general
terminology used by Rocketdyne to characterize the final design capable
 of achieving program goals.
                                    1-10

-------
reduced equipment usage are listed in Table 1-4.  Replacement of wornout
furnaces, tuning and changes in thermostat anticipator setting represent
the most effective control techniques with overall combustible emission
reductions ranging from 16 to 65 percent for CO, 3 to 87 percent for UHC,
59 percent for smoke, and 17 to 33 percent for particulates.  Installation
of delayed action solenoid valves and reduced firing capacity through
minor modification or installation of a new flame retention burner are
effective in reducing excessive smoke emissions during furnace start-up
and shut-down periods.  Reported average smoke reductions range from 24 to
82 percent.  In general, all these techniques result in fuel savings
sometimes as high as 39 percent in addition to lowering combustible
emissions.
       Application of control technology to commercial  heating equipment
is very limited.  Theoretically, the flame quenching and surface
combustion concepts  investigated for gas-fired residential equipment could
also apply to commercial heaters burning natural gas.  Similarly,
low-NO  burner designs for distillate oil firing or optimum air-fuel
      /\
mixing concepts could possibly be scaled up to the larger commercial
equipment.
       NOX control technology from the gas- and oil-fired industrial
boiler source category include low-NO  burners, staged  combustion, flue
                                     A
gas recirculation, load reduction and low excess air operation.   These
techniques could possibly be applicable to commercial size boilers of
similar design.  Low-N0x burners represent the most attractive control
alternative for this boiler size category.  Some U.S. companies are
currently working on new burner design concepts, primarily for oil-fired
boilers.  Most of these efforts, however, have been oriented toward
industrial (2.9 to 73.3 MW heat input) size boilers.
1.4    ENVIRONMENTAL AND COST IMPACTS
       As a part of the NOV EA program, a Blueray low-NOv high-
                          A                             A
efficiency residential furnace was tested in the field  to quantify the
environmental impact of low-NOx residential systems.  Results from these
tests were then compared with those from another program in which seven
conventional oil-fired residential heaters (five warm air and two hot
water) using high pressure atomizing burners were field tested.
                                    1-11

-------
                          TABLE  1-4.   PERFORMANCE  SUMMARY OF CONTROLS  FOR  REDUCTION  OF  SEASONAL
                                         COMBUSTIBLE,  SMOKE AND PARTICULATE EMISSIONS  FROM OIL-FIRED
                                         RESIDENTIAL  HEATERS
Control
Replacement of worn-out
units
Tuning and scheduled
seasonal maintenance
Delayed action solenoid
valves
Reduced excessive firing
capacity with conven-
tional burner
Reduced excessive
firing capacity with new
retention burner
Installation of positive
chimney dampers
Change In thermostat
anticipator setting
Overnight thermostat
cut -back (3-5K)
Percent Reduction (Average)
CO UHC Smoke Partlculates
(65) (87) NC* (17)
(16) (3.0) (59) (7.0)
NA NA 60-90 NA
(80)
(14) NA 10-38 (3.7)
(24)
(14) NA 80-85 (3.7)
(82)
2.0-19 NA NA 2.3-17
(11) (10)
41-45 NA NA 31-33
(43) (33)
9.1-27 NA NA 12-24
(17) (15)
Percent
Improvement
In Fuel Saving
NAb
1.7 percent
average efficiency
Increase
NA
5.6-2.5
(14)
14-39
(30)
3-9
0-2
7-15
1978
Installed
Control
Cost
$650-J1000C
for new warm
air furnaces
$38-$60c
$43C
$52<:
$385C
$200C
Minimal
Minimal
Comments
Nine percent of the existing resi-
dential heaters were found in need
of replacement. Recent cost
estimates.
Tuning results is an increase in
efficiency for some units and a
decrease in efficiency for others.
Smoke emission reduction primarily
during start-up and shut-down.
Installation of flame retention
head cone plus modifications to
reduce firing capacity by about
36 percent. -
Installation of new lower capacity
burner with flame retention head
retention head. Firing capacity
reduced by 43 percent.
Large variation In pollutant
slon reduction due to changes
In furnace cycle frequency.
Recent cost estimate.
Very effective for residential
units with high cyclic frequency.
Cost does not take Into account
improved home insulation which
might be necessary with thermostat
cut-back.
I

no
           »NC ' No change
           bNA - Not available
           cCosts for material and labor are typical of New England area.  Original costs reported
            for years other than 1978 were corrected for inflation using Gross National Product (GNP)
            implicit price inflators (Reference  1-9)

-------
       In general, the Blueray unit showed decreases of criteria and
noncriteria pollutants when compared with conventional heaters.  For
cyclic operation, particulate, S03, and trace elements were 70 to
80 percent lower for the Blueray low-NOv furnace.  However, total
                                       A
organic emissions from the Blueray unit were about five times higher than
the average emissions from the seven conventional heaters.  Switching from
continuous to cyclic operation, NO  emissions from the Blueray furnace
                                  A
decreased because of lower N0x during transient furnace operation.
Particulates and trace element emissions generally remained unchanged.
Emissions of Fe, Ni and possibly Cr, Mn, and Mo decreased significantly
when switched to cyclic operations.  However, trace element results need
verification since sample contamination from steel metal surfaces was
suspected.
       A rapid screening of potentially hazardous emissions from the
Blueray furnace  and conventional oil-fired heaters was performed using the
Source Analysis  Model (SAM IA) (Reference 1-10).  For the purpose of
screening pollutant emissions data to identify species requiring further
study, a Discharge Severity (DS) is calculated using SAM IA procedures.
DS is defined as the ratio of a pollutant species discharge concentration
to that species' Discharge Multimedia Environmental Goal (DMEG).  The DMEG
value represents a threshold, or "allowable" discharge concentration of a
pollutant, above which adverse health or ecological effects may occur.
When DS exceeds  unity, more refined chemical analysis may be required to
quantity specific compounds present.
       Table 1-5 lists discharge severities for those species with  DS
greater than 0.1.  The DS for NO  was significantly lower for the
                                A
Blueray furnace, decreasing from a value of about 5 for conventional units
(representing potential  environmental hazard), to less than 1.0 for the
low-NO  unit.  Of the trace elements, Cr and Ni emissions present the
      /\
greatest potential hazard; in all cases their DS is a sizeable fraction of
total stream DS.  However, measured levels of these metals may be an
artifact of the stream sampling methodology.  The flue gas sampling trains
in both the conventional  furnace test program and the NO  EA contained
                                                        J\
many stainless steel components.  Thus, some of the reported Cr and Ni
                                    1-13

-------
  TABLE 1-5.  FLUE GAS DISCHARGE SEVERITIES GREATER THAN 0.1 FOR THE
              BLUERAY FURNACE AND CONVENTIONAL OIL-FIRED HEATERS



Pollutant
NOX
SO 2
SO 3
CO
Arsenic (As)
Calcium (Cd)
Chromium (Cr)
Cobalt (Co)
Copper (Cu)
Iron (Fe)
Lead (Pb)
Nickel (Ni)
Thallium (Th)
Amines
Carboxylic acid
Total Stream DS
Blue ray Furnace ,
(Reference 1-11)
Continuous
Operation
0.86
1.6
0.15
0.17
0.23
0.17
85
0.14
0.075
0.42
0.14
4.5
0.37
NFC
0.20
95.7
Cyclic
Operation
0.60
2.1
0.77
1.1
0.27
0.11
5.5
0.11
0.055
0.046
0.14
0.73
0.41
NFC
2.3
1 5. 5
	
Conventional Furnace
(Reference 1-12)
Cyclic
Operation
4.73
6.3a
4.5
0.3a
0.60
0.85
22
NDb
0.60
0.011
0.21
15
NDb
1.6
NFC
59.0
aPollutant not measured in test program,
 DS calculated from AP-42 emission factors:
 S02, 106 ng/J; CO, 15 ng/J
"ND:   Species not analyzed for
CNF:   None found
NOX, 55 ng/J;
                                 1-14

-------
could have come from the sampling train itself rather than being a
significant component of the flue gas.
       For both types of units SO,, emissions were flagged and emissions
of certain organic categories had DS values greater than 1.  For the
conventional units amines were flagged as being of potential concern; for
the Blueray unit carboxylic acids would be of potential concern under
cyclic operation.  The DS for NO  exceeds 1 for conventional units, but
                                A
is less than 1 for the low-NOx Blueray unit under both continuous and
cyclic operations.
       In summary, flue gas stream Total Discharge Severity (TDS) for
typical conventional units appears to fall between the TDS for the
low-NO  unit under cyclic (normal) operation and that for both the
      A
low-NO  unit under continuous operation.  If Cr and Ni are removed from
      A
the TDS calculations, adjusted TDSs of 32.7, 5.3, and 18.3 result for the
conventional, Blueray continuous, and Blueray cyclic data, respectively.
Thus, if measured Cr and Ni indeed comes from the sampling train, then the
low NO  unit's TDS under both cyclic and continuous operation is lower
      X
than that of the conventional units.  This suggests that using the Blueray
design to control NO  from oil-fired heating units is environmentally
                    A
sound.
       Table 1-6 summarizes estimated cost data for the most effective
NO  control alternatives for residential heating systems.  As indicated,
  A
retrofit of the controlled mixing burner head (EPA/Rocketdyne) for
residential oil-fired warm air furnaces represents the most cost-effective
alternative to achieve a NO  emission level of about 45 ng/J of useful
                           /\
heat.  Surface combustion, pulse combustor and catalytic burner for
gas-fired units and the Rocketdyne developed technologies for oil-fuel
units are not commercially available.  The payback periods listed in the
table are estimates based on the time required to recover the money spent
for the initial investment of installing NO  control equipment.  Since
                                           J\
all of these control alternatives bring about an increase in thermal
efficiency, and thus fuel savings, the initial investment cost is often
recouped over a one year or less time period.
                                     1-15

-------
                      TABLE   1-6.    COST  IMPACT  OF  NOX CONTROL ALTERNATIVES
Control
Amana (HTM) Furnace
Modulating Furnace
Surface Combustion
Burner (Infrared Bratko
type)
Pulse Combustion
Burnerb
Catalytic Combustion
Burner0
Flame Retention Burner
Head
Flame Retention Burner
EPA/Rocketdyne Burner
Head
EPA/Rocketdyne Furnace
Bluer ay Furnace
Fuel
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Distillate Oil
Distillate Oil
Distillate Oil
Distillate Oil
Distillate Oil
Achievable NOX Level
ng/J Useful Heat
12
(390 ng/m3 fuel)
35
(920 ng/m3 fuel)
12
(380 ng/m3 gas)
21
(683 ng/m-3 gas)
Estimate 5
(163 ng/m3 gas)
50
(1.8 g/kg fuel)
50
(1.8 g/kg fuel)
45
(1.6 g/kg fuel)
29
(0.7 g/kg/fuel)
20
(0.7 g/kg fuel)
1978
Incremental
Investment Cost
J100-J300 over cost of
conventional furnace
$50-$250 over cost of
conventional furnace
J100-J200 over cost of
conventional furnace/
heater
$300-$600 over cost of
conventional furnace/
heater
$150-$250 over cost of
conventional furnace/
heater
$52 — retrofit
including installation
$385 — retrofit of
reduced capacity burner
$43 — retrofit
including installation
$250 over cost of
conventional furnace
$100 over cost of
conventional furnace
Cost Effectiveness
$/ng/Ja
1.7-5.2
1.4-7.0
1.7-3.4
6.1-12.2
2.3-3.9
2.6
12.8
1.3
4.2
1.7
Payback Period Based
on Annual Fuel Bill
of $500
1-3 years
1-3.8 years
3.5-8.0
1.7-3.5
1.4-2.3
Less than 1 year
3.5 years
Less than 1 year
2.5 years
1 year
aBased on uncontrolled  NOX emissions of 70 ng/J heat output for natural gas-fired heaters and 80  ng/J heat output
 for  distillate oil-fired heaters.  Cost-effectveness is based of  the differential investment cost of the control.
''Based on installation  of a condensing system where seasonal efficiencies can be as high as 95 percent.

-------
1.5    DATA NEEDS AND RECOMMENDATIONS
       A modest amount of information has been gathered on emissions from
residential space heating equipment.  In addition, control alternatives
for N0x and combustible pollutants have also been investigated.  Some
low-NOx and high efficiency furnace designs are commercially available,
while other equally effective designs are either at final demonstration
stages or await commercialization.  Performance tests on these improved
heating designs are being gathered through EPA sponsored field and
laboratory programs.  These and other test programs will aid in further
documenting the performance, reliability of these advanced controls and
quantifying their impact on other pollutant emissions.
       Cost data on N0x control  alternatives for residential heating
systems were generally sparse and imprecise.  This lack of definitive cost
data prevented a detailed economic impact assessment of widespread
implementation of control alternatives.   As advanced controls become
available, future EA programs should quantify the cost impact of NO
                                                                   A
control implementation to achieve specific level of controls.
       Investigative efforts on  NOY control alternatives for commercial
                                  A
size steam and hot water boilers burning gas or oil  is also scarce.  While
it can be speculated that some boiler designs lend themselves to NO
                                                                   A
control techniques developed for industrial size boilers, little
experimental data exist to confirm this.  Low-NO  burner technology for
                                                A
heat input capacities in the size range of 0.1 to 2.9 MW (0.4 to 10 x
10  Btu/hr) shows promise based  on advanced burner technology developed
for both residential units on the small  side and industrial units on the
larger side.
       NO  control technology for solid-fuel-fired residential  and
         A
commercial equipment, is also very limited.  Past and on-going test
programs have mainly dealt with  quantifying the pollutant levels and
identifying equipment operating  parameters and fuel  characteristics which
have some impact on these levels.  Primary pollutants of interest for this
category of equipment have been  particulate and smoke emissions as well as
levels of unburned hydrocarbons, toxic elements and polycyclic organic
matter (POM).  The simplicity of the solid-fuel-fired equipment, whether
coal- or wood-fired, often does  not permit extensive modifications of
                                    1-17

-------
existing equipment or operating procedures to reduce NO  levels.
                                                       A
Investigative efforts in this area should continue to determine potential
NO  control technology applicable to new unit design while still
  A
concentrating on reducing the impact of other criteria and noncriteria
pollutant emissions.
                                    1-18

-------
                          REFERENCES FOR SECTION 1
1-1.   Water!and, L. R., et al.,  "Environmental  Assessment of Stationary
       Source NOX Control Technologies -- Final  Report,"  Acurex Draft
       Final Report, EPA Contract 68-02-2160,  Acurex Corp.,  Mountain View,
       CA, April 1980.

1-2.   Devitt, T., et al., "The Population and Characterization of
       Industrial/Commercial Boilers," EPA 600/7-79-178a, NTIS
       PB-80-150881, August 1979.

1-3.   Howekamp, D. P., "Flame Retention -- Effects on Air Pollution,"
       U.S. Department of Health, Education and Welfare,  presented  at  the
       Ninth Annual Convention of National Oil Fuel Institute, Atlantic
       City, New Jersey, June 1970.

1      Hall, R. E., et al., "Study of Air Pollutant Emissions from
       Residential Heating Systems," EPA-650/2-74-003, NTIS-PB 229  697,
       January 1974.

1-5.   Personal communication with Charles Allen, Department of Energy
       Information Administration (EIA), Washington, D.C., on preliminary
       data from Annual Report to Congress, May 1, 1979.

1-6.   Brookman, G. T., and W. Kalika, "Measuring the Environmental Impact
       of Domestic Gas-Fired Heating Systems," in the Proceedings of the
       67th Annual Meeting, Air Pollution Control Association, June 1974.

1-7.   U.S. Environmental Protection Agency, "Compilation of Air Pollution
       Emission Factors, Second Edition With Supplements," EPA AP-42,
       Research Triangle Park, North Carolina, 1972-1977.

1-8.   Barrett, R. E., et al., "Field Investigation of Emissions from
       Combustion Equipment for Space Heating," EPA-R2-084a, (API
       Publication 4180) NTIS-PB 223 148, June 1973.

1-9.   "Statistical Abstracts of the United States -1978," U.S.
       Department of Commerce, 99th Annual Edition, Section 15,
       pp 480-485, September 1978.

1-10.  Shalit, L. M.,  and K. J. Wolfe, "SAM/IA:  A Rapid Screening Method
       for Environmental Assessment of Fossil  Energy Process Effluents,"
       EPA-600/7-78-015, NTIS-PB 277 088, February 1978.

1-11.  Higginbotham, E. B., "Combustion Modification Controls for
       Residential and Commercial Heating Systems:  Volume II.  Oil-fired
       Residential Furnace Field Test," EPA-600/7-81-123b, July 1981.

1-12.  Surprenant, N. F., et al., "Emission Assessment of Conventional
       Stationary Combustion Systems: Volumn 1.  Gas- and Oil-Fired
       Residential Heating Sources,"  EPA-600/7-79-029b,  NTIS-PB 298-494,
       May 1979.


                                    1-19

-------
                                 SECTION 2
                                INTRODUCTION

       This report assesses the operational, economic,  and environmental
impacts from applying combustion modification  NO  controls to
                                                A
residential and commercial combustion equipment with heat input  capacity
less than 2.9 MW (10 x 106 Btu/hr).  With more NOX controls being
implemented in the field and expanded control  development anticipated  for
the future, there is currently a need to:  (1) ensure that the current and
emerging control techniques are technically and environmentally  sound,  and
compatible with efficient and economical operation of systems  to which
they are applied, and (2) ensure that the scope and timing of  new  control
development programs are adequate to allow stationary sources  of NO to
                                                                   /\
comply with potential air quality standards.  The NO  EA program
addresses these needs by (1) identifying the incremental multimedia
environmental impacts of combustion modification controls, and
(2) identifying the most cost-effective source/control  combinations to
achieve ambient N02 standards.
2.1    BACKGROUND
       Since the 1970 Clean Air Act Amendments, techniques have  been
developed and implemented that  reduce NOX emissions by a moderate  amount
(30 to 60"percent) for a variety of stationary source/fuel combinations.
In 1971, EPA set NSPS for large steam generators burning gas,  oil, and
coal (except lignite).  Recently, more stringent standards for utility
boilers burning bituminous and  subbituminous coals have been promulgated,
along with new standards for lignite fired utility boilers.  In  addition,
NSPS have been proposed for stationary gas turbines reciprocating  internal
combustion engines and are under study for industrial steam generators.
Local  standards also have been  set, primarily for new and existing large
steam generators and gas turbines,  as parts of State Implementation Plans
in several areas with NOX problems.

                                    2-1

-------
       Because of the relaxation of mobile standards, coupled with the
continuing growth rate of stationary sources, NO  control for stationary
sources has become more important for maintaining air quality.  Thus more
stringent controls than current and impending NSPS provide will be
required.  To meet these standards the preferred approach is to control
new sources by using low-NO  redesigns.
2.2    ROLE OF RESIDENTIAL AND COMMERCIAL HEATING SYSTEMS
       This source category includes warm air furnaces and hot water
heaters for home heating, and small commercial hot water or steam boilers
for plant heating and air conditioning.  Home heating equipment consume
the largest quantity of fuel within this source category.  In 1977,
domestic space and water heaters alone consumed about 8 EJ* or
approximately 20 percent of the total U.S. energy used by stationary
combustion sources (Reference 2-1).  Commercial boilers with heat input
capacity less than 2.9 MW (10 x 10  Btu/hr) consumed approximately an
additional 4.15 EJ, or about 10 percent of total U.S. fuel consumption for
stationary combustion sources.
       Residential combustion equipment warm air furnaces, steam and hot
water heaters and warm air space heaters (combined) is the fifth largest
contributor of NO  emissions in the U.S.  Figure 2-1 shows that warm air
                 /\
central furnaces are responsible for 14 percent of NOV emissions from
                                                     x        /-
all sources with heat input capacity less than 2.9 MW (10 x 10  Btu/hr)
or about 0.9 percent of total NO ; steam and hot water heaters
                                A
contributed 26.1 percent or 1.8 percent of total NO ; while warm air
                                                   ^
space heaters contributed another 4.3 percent, or 0.3 percent of total
NO  (updated from Reference 2-3).  Steam and hot water boilers
  y\
(firetubes, watertubes, and cast iron) with a capacity less than 2.9 MW
(10 x 10  Btu/hr), used in both commercial and industrial sectors,
contributed about another 3.0 percent to the total NO  emissions.
                                                     J\
       The impact of residential and commercial heating systems on ambient
NO  levels is much more severe than these low percentage points
  X
indicate.  The seasonal use pattern, low stack heights and wide
geographical distribution of residential and commercial heating systems
*Does not include about 2 EJ of electricity also used for residential
 heating.
                                    2-2

-------
               Conmerdal and residential
               <2.9 MW (10 x 106) Btu/hr) 6.8%


                             Incineration 0.4J


                             Noncombustlon 1.9%

                             Gas turbines 2.0'

                      Others (fugitive) 4.U


          Irdustrial nrocess heaters 4.1%



        Industrial and commercial boilers
         >2.9 MW (>10 x 10b Btu/hr) 9.71
                                            Reciprocating
                                            1C engines
                                            18.9%
                          Total  from ill  sources:  10.5 Tg/yr (11.6 » 106 tons/yr
                             Warm air space heaters 4.3'.
               Miscellaneous cot*ust1on"   11.4%
                  Firetube boilers \2.K
                Uitertube boilers 1.41
                                                                      Ham air
                                                                      central
                                                                      furnaces 14.0%
                                                               Steam and hot
                                                               water heaters
                                                               26.
                Total from all sources with  capacity less than 2.9 MW
                (10 x 106 Btu/hr):  0.709 Tg/yr (0.781 x 106 tons/vr)

                'includes coolinq and air conditioning
Figure  2-1.
Distribution  of  stationary  anthropogenic  NOX emissions  for
 the  year  1977  (controlled  NOX levels)  (Reference 2-2).
                                                2-3

-------
are often the cause of high NCL ambient levels in populated urban
areas,  the contribution of these sources often exceeds that of other
stationary or transportation sources during the "heating season"
(References 2-4 and 2-5).  With the increasig number of homes and
commercial buildings requiring heating and air combustion systems will
continue to be a problem unless adequate controls are developed.  The
problem may be aggravated as fuels such as residual oils or stoker coal
which show a propensity for higher NO  formation, becomes more
                                     A
attractive in the face of shortages and higher prices of natural gas and
distillate oils normally used for home and commercial heating.
       Given this background and their potential for NOX control,
residential and commercial heating systems were selected as a major source
category to be studied under the NO  EA program.  The "Preliminary
                                   /\
Environmental Assessment of Combustion Modification Techniques"
(Reference 2-5) concluded that modifying combustion process conditions is
the most effective and widely used technique for achieving 20 to
70 percent reduction in oxides of nitrogen.  Nearly all current NO
                                                                  /\
control applications use combustion modifications.  Other approaches, such
as treating postcombustion flue gas, are generally not considered feasible
for application on small residential and commercial heating systems.
2.3    OBJECTIVE OF THIS REPORT
       This report evaluates and compares the important environmental and
process engineering aspects of available or emerging combustion
modification techniques for residential and commercial heating systems
with special emphasis on central warm air furnaces.  Subobjectives of this
evaluation are:
       •   Evaluate control impact on total multimedia emissions
       t   Identify the effect of control application on equipment
           performance and identify potential problem areas
       •   Estimate the economics of control implementation
       •   Estimate the limits of control achievable for the significant
           sources as fuels
       •   Identify research and development and/or testing needs to
           optimize combustion modification techniques and to upgrade
           their assessment
                                    2-4

-------
2.4    ORGANIZATION OF THIS REPORT
       The components of the environmental assessment reported here are as
follows:
       •   Characterize the source category with regard to equipment,
           fuels and emissions (Section 3)
       •   Review pollutant formation mechanisms and relate fuels to their
           emissions potential (Section 4)
       •   Evaluate the performance of current and developing NO
                                                                /\
           control techniques available for implementation (Section 5)
       •   Estimate the capital and operating costs, including energy
           impacts of implementing NO  control (Section 5)
                                     rt
       e   Evaluate the environmental impact of NO  controls through the
                                                  /\
           analysis of incremental emissions (Section 6)
       e   Assess the total impact of NO  controls on ambient air,
                                        /\
           economics, energy and operations and maintenance of the
           residential equipment, thereby evaluating the effectiveness of
           current and emerging control technology (Section 6).
With some exceptions due to the nature of the subject treated, the
reporting format conforms to the "Environmental Assessment Report"
guidelines developed by EPA's Industrial Environmental Research Laboratory
for disseminating results of EPA's environmental assessment program.
                                    2-5

-------
                          REFERENCES FOR SECTION 2
2-1.   Personal  communication with  C.  Allen,  Department of  Energy,
       Washington,  D.C.,  on preliminary data  from Energy Information
       Administration (EIA) Annual  Report  to  Congress,  May  1,  1979.

2-2.   Waterland,  L.  R.,  et al^,  "Environmental  Assessment  of  Stationary
       Source NOX  Control  Technologies ~  Final  Report," Acurex  Draft
       Final  Report FR-80-57/EE,  EPA Contract 68-02-2160, Acurex Corp.,
       Mountain  View, CA,  September 1979.

2-3.   Salvesen, K. G.,  et al.,  "Emissions Characterization of Stationary
       NOX Sources, EPA-60077^78-120a, NTIS-PB 284 520, October  1977.

2-4.   Howekamp, D.P.,  "Flame Retention — Effects on Air Pollution,"  U.S.
       Department  of  Health,  Education and Welfare,  presented  at the Ninth
       Annual Convention  of National Oil Fuel  Institute, Atlantic City,
       N.J.,  June  1970.

2-5.   Hall,  R.  E., et  aj_., "Study  of  Air  Pollutant  Emissions  from
       Residential  Heating Systems," EPA-650/2-74-003,  NTIS-PB 229  697,
       January 1974.

2-6.   Mason, H.B., et  al., "Preliminary Environmental  Assessment of
       Combustion  ModTfication Techniques, Volume II, Technical  Results,"
       EPA-600/7-77-1196,  NTIS-PB 276  681/AS,  October 1977.
                                   2-6

-------
                                 SECTION 3
                          SOURCE CHARACTERIZATION
       This section characterizes space heating combustion sources with
heat input capacity less than 2.9 MW  (10 x 106 Btu/hr).  This size
category covers  steam and hot water systems and warm air furnaces in both
the residential  and commercial sectors.  In addition, it includes process
steam or hot  water units in the  industrial sector with capacity less than
2.9 MW (10 x  10  Btu/hr).  Equipment  types, population and installed
capacity, current design practice, and areas of environmental concern are
identified and discussed.
3.1    EQUIPMENT TYPES
       Figure 3-1 summarizes the types of residential and commercial
combustion equipment used for space heating.  For this report the
distinction between residential  and commercial units is arbitrarily set at
0.1 MW (400,000  Btu/hr) heat input capacity, although, warm air furnaces,
space heaters, and hot water or  steam units below this firing rate are
also used in  commercial establishments.  Units with capacity above 0.1 MW
(400,000 Btu/hr) are rarely found in  single family residential dwellings.
Figure 3-1 indicates that there  are four generic equipment types --
(1) room heaters or direct vent  heaters used for domestic warm air, (2)
space or unit heaters only used  for commercial direct heating, (3) warm
air furnaces  used for both residential and commercial heating, and  (4) hot
water or steam systems also used for  domestic and commercial heating.
Warm air room heaters or direct  vent  heaters are single room heaters which
may be mounted in the wall, floor or  from the ceiling.  Warm air furnaces
are central air  units delivering warm air to a number of rooms.  In many
cases, especially in commercial  systems the warm air heating system is
integral with a  central air conditioning system.  Space or unit heaters
are used solely  for commercial heating, exhausting hot combustion products

                                    3-1

-------
co
          Residential
          <0.12 MW (<0.4 x 106 Btu/hr)
          Commercial
          0.12-2.9 MW
          (0.4 -10 x 106 Btu/hr)
Room or
heaters
Warm air
furnaces
— Steam or hot 	
water boilers
heaters
_ Wall un
— Miscell
Natural
forced
— Cast ir
>— Steel
r— Coil
— Steel
its
nits
aneous
and
draft
on
                                                              I— Rooftop heaters
                                           -Warm air space  or—I
                                            unit heaters
                                                              '— Unit heaters
.Warm air.
 furnaces
t
                                                                 Direct
                      Indirect
                                                               I—Cast iron
                                         —Hot water
                                            and steam boilers3
                                                                 •Firetube
                                                               1—Water tube
Natural  gas, distillate oil

Natural  gas

Natural  gas, distillate oil

Natural  gas, distillate oil


Natural  gas, distillate oil, coal

Natural  gas, distillate oil, coal

Natural  gas, distillate oil

Natural  gas, distillate oil,
residual  oil,  coal

Natural  gas, distillate oil


Natural  gas, distillate oil


Natural  gas


Natural  gas, distillate oil
                                         Natural gas, distillate oil,
                                         residual oil, coal

                                         Natural gas, distillate oil,
                                         residual oil, coal

                                         Natural gas, distillate oil,
                                         residual oil, coal
          aAlso found in  the  industrial sector.
                    Figure  3-1.   Distribution  of  residential  and  commercial  heating  systems.

-------
directly into the space being heated.  Finally, hot water or steam
systems, may be utilized for either space heating or for process hot water
or steam.  The following sections present the population distribution of
these commercial and residential units by fuel, equipment type, and region.
3.1.1  Residential Units
       Table 3-1 lists domestic heating populations based on 1976 U.S.
Census data by equipment type and fuel (Reference 3-1).  The Census data
indicate that central warm air furnaces are the most common residential
combustion equipment accounting for nearly 53 percent of the entire
population.  Natural gas is currently the principle house heating fuel
accounting for about 56 percent of total fuel used.  Oil and kerosene rank
second as sources of energy with about 22 percent, while electricity,
which has recently grown in popularity, in 1976 accounted for nearly
14 percent of the total energy used.
       Table 3-2 lists the distribution of residential equipment by fuel
type for the four U.S. Census Regions.  In the Northeast Region, a higher
percentage of fuel oil is consumed than other fuels, whereas in all other
regions  natural gas  is the predominant domestic fuel.  Equipment
distribution also varies regionally (Table 3-3).  In the Northeast Region,
steam or hot water systems comprise the highest percentage of all
residential equipment types.  This indicates that, although gas-fired warm
air systems dominate nationally, oil-fired hot water or steam units can be
significant air pollution contributors on a regional basis.
3.1.2  Commercial Units
       With the exception of the hot water or steam boilers below 2.9 MW
(10 x 10  Btu/hr) firing capacity, no compilation of user statistics or
sales was found for  commercial size space heating equipment.  However,
discussion with manufacturers revealed the following:
       •   There are both gas-fired and oil-fired unit heaters and warm
           air furnaces or duct heaters in the commercial size range
           designated in this report, 0.1 to 2.9 MW (0.4 to 10 x 106 Btu/hr)
       t   Although  there are a few unique gas-fired designs, in general
           the combustion systems of commercial heating equipment is
           similar in design to the residential equipment
                                    3-3

-------
                TABLE  3-1.  POPULATION AND  RANKING OF DOMESTIC HEATING  SYSTEMS BY  TYPE (1976)  --  1000 UNITS
CO
-p.
Heating Equipment
Harm Air Furnace
Steam or Hot Water
Floor, Wall or Pipeless
Furnace
Room Heater wtth Flue
Room Heaters w/o Flue
Built-in Electric Units
Others (Fireplaces,
Stoves)
Total
Natural Gas
25,042
(34.1)a
5,308
(7.2)
5,471
(7.4)
2,767
(3.8)
2,331
(3.2)
--
300
(0.4)
41,219
(56.0)
Bottled or
Liquified
Petroleum Gas
1,961
(2.7)
112
(0.2)
503
(0.7)
636
(0.9)
938
(1.3)
--
90
(0.1)
4,240
(5.8)
Oil or Kerosene
6,729
(9.1)
7,987
(10.9)
422
(0.6)
1,183
(1.6)
68
(0.1)
—
62
(0.1)
16,451
(22.4)
Electricity
4,877
(6.6)
--
--
--
--
4,794
(6.5)
479
(0.7)
10,150
(13.8)
Other Fuel
179
(0.2)
192
(0.3)
22
—
--
--
1,090
(1.5)
1,483
(2.0)
Total
38,787
(52.7)
13,598
(18.5)
6,417
(8.7)
4,586
(6.2)
3,337
(4.5)
4,794
(6.5)
2,021
(2.7)
73,543
(100)
                    aPercent of  total  systems given in parenthesis.

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     TABLE 3-2.   REGIONAL DISTRIBUTION OF RESIDENTIAL HEATING
                 EQUIPMENT BY FUEL (1976) -- 1000 UNITS
Fuel
Natural Gas
Bottled or
Liquified
Petroleum Gas
Oil, or
Kerosene
Electricity
Coal, Coke
Other,
incl. Wood
Total
Northeast
6,140
(8.4)a
125
(0.2)
9,161
(12.5)
846
(1.1)
162
(0.2)
101
(0.1)
16,535
(22.5)
Northcentral
13,803
(18.8)
1,337
(1.8)
3,004
(4.1)
1,366
(1.9)
102
(0.1)
105
(0.1)
19,717
(26.8)
South
11,449
(15.6)
2,367
(3.2)
3,488
(4.7)
5,498
(7.5)
193
(0.3)
588
(0.8)
23,583
(32.1)
West
9,826
(13.4)
411
(0.6)
798
(1.1)
2,441
(3.3)
28
(0.04)
204
(0.3)
13,708
(18.6)
Total
41,219
(56.0)
4,240
(5.8)
16,451
(22.4)
10,151
(13.8)
485
(0.7)
988
(1.4)
73,543
(100)
aPercent of total systems given  in  parenthesis.
                                                      Northeast
                                3-5

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         TABLE 3-3.  REGIONAL DISTRIBUTION OF RESIDENTIAL HEATING
                     EQUIPMENT BY FUEL (1976) — 1000 UNITS
Equipment
Warm Air
Furnaces
Steam or Hot
Water
Floor, Wall
or Pipeless
Furnace
Room Heater
with Flue
Room Heater
without Flue
Built-in
Elect. Units
Others (Fire-
places, Stoves)
Total
Northeast
5,984
(8.1)a
8,923
(12.1)
174
(0.2)
521
(0.7)
51
(0.1)
733
(1.0)
148
(0.2)
16,534
(22.5)
Northcentral
13,782
(18.7)
3,068
(4.2)
556
(0.8)
1,220
(1.7)
52
(0.1)
899
(1.2)
140
(0.2)
19,717
(26.8)
South
11,922
16.2)
1,070
(1.5)
2,365
(3.2)
2,049
(2.8)
3,112
(4.2)
1,674
(2.3)
1,390
(1.9)
23,582
(32.1)
West
7,100
(9.6)
538
(0.7)
3,321
(4.5)
796
(1.1)
122
(0.2)
1,488
(2.0)
344
(0.5)
13,709
(18.6)
Total
38,788
(52.7)
13,599
(18.5)
6,416
(8.7)
4,586
(6.2)
3,337
(4.5)
4,794
(6.5)
2,022
(2.7)
73,542
(100)
aPercent of total systems given in parenthesis.
                                                          Northeast
                                   3-6

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       •   The majority of unit heaters are gas-fired and some of these
           are "infrared type" burners where surface combustion occurs on
           a refractory grid
       t   Warm air heaters are either indirect gas-or-oil-fired similar
           to the residential units or direct gas-fired where the
           combustion gases are mixed with the air being heated.  This
           heated air may be used for space heating or for drying.
       t   Indirect fired warm air heaters are either larger versions of
           residential design or duct heaters.  Duct heaters are usually
           part of a central air conditioning system or roof top climate
           control system.
       •   Rooftop gas-fired central air systems are often utilized in
           commercial buildings.  In more severe climates and high-rise
           buildings a central boiler, either gas- or oil-fired, is
           utilized.
       Three types of burner systems are commonly used in commercial space
heating equipment; these are:
       a   The atmospheric gas-fired single port, ribbon or multiport
           burner
       •   The retention head distillate oil-fired power burner
       •   The direct gas-fired duct burner
The first two designs are similar to those used for residential systems.
These burner systems will be discussed with regard to their pollution
impact and control potential in the following sections of this report.
       Steam and hot water units with heat input capacity below 2.9 MW
(10 x 10  Btu/hr) can be found in both the commercial as well as the
industrial sector.  These units can be divided into three general
equipment types -- watertubes, firetubes, and  cast iron boilers.  A
recent population distribution of these commercial size boilers has been
published by Devitt, et aiK, (Reference 3-2).  Tables 3-4 and 3-5 list
respectively the 1977 commercial and industrial population and installed
-capacity for the various types of boilers within this size category.
       In the commercial sector (Table 3-4), cast iron boilers account for
over 90 percent of all installed steam or hot water units.  Nearly 66
percent of these units have heat input less than 0.1 MW (400,000 Btu/hr).
Firetube boilers are the second most numerous boiler type accounting for

                                    3-7

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     TABLE 3-4.  POPULATION OF BOILERS WITH <2.9 MW  (10  x  106  Btu/hr)
                 HEAT INPUT CAPACITY IN USE  IN  COMMERCIAL  SECTOR  —
                 1977 NUMBER OF UNITS (INSTALLED CAPACITY  MW)
Equipment
Type
Watertube
Watertube
Total
Firetube
Firetube
Total
Cast Iron
Cast Iron
Total
All Equip-
ment Types
Size Range MW
(106 Btu)
£0.1 (0.4)
0.1-0.4
(0.4-1.5)
0.4-2.9
(1.5-10)
<0.1-2.9
0.4-10)
£0.1 (0.4)
0.1-0.4
(0.4-1.5)
0.4-2.9
(1.5-10)
0.1-2.9
TO. 4-10)
<0.1 (0.4)
0.1-0.4
(0.4-1.5)
0.4-2.9
(1.5-10)
<0.1-2.9
TO. 4-10)
<0.1-2.9
TO. 4-10)
Stoker
Coal
—
392
(no)
630
(955)
1,022
(1,065)
—
13,459
(3,940)
2,866
(4,830)
16,325
(8,770)
90 , 630
(4,810)
37,408
(9,840)
15,826
(10,610)
143,864
(25,260)
161,211
(35,095)
Residual
Oil5
—
399
(140)
772
(1,160)
1,171
(1,300)
—
15,731
(4,610)
5,163
(8,310)
20,894
(12,920)
162,855
(12,010)
57,291
(12,860)
19,428
(18,140)
239,574
(43,010)
261,639
(57,230)
Distillate
Oil*
—
1,552
(550)
1,183
(1,380)
2,735
(1,930)
—
16,001
(4,690)
5,636
(9,070)
21,637
(13,760)
102,266
(7,530)
35,983
(8,090)
12,196
(11,370)
150,445
(26,990)
174,817
(42,680)
Natural
Gas5
—
893
(310)
723
(985)
1,616
(1,295)
—
30,889
(9,050)
6,715
(10,920)
37,604
(19,970)
421,033
(30,970)
175,055
(40,260)
51,221
(43,570)
647,309
(114,800)
686,529
(136,065)
Total
—
3,236
(1,110)
3,308
(4,480)
6,544
(5,590)
—
76,080
(22,290)
20,380
(33,130)
96,460
(55,420)
776,784
(55,320)
305,737
(71,050)
98,671
(83,690)
1,181,192
(210,060)
1,284,196
(271,070)
aA number of boilers  have dual  gas/oil  firing  capability.  Units  are
 listed here by the primary fuel  burned.
                                  3-8

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     TABLE 3-5.  POPULATION OF BOILERS WITH <2.9  MW  (10  x  TO6  Btu/hr
                 HEAT INPUT CAPACITY IN USE  IN  THE  INDUSTRIAL  SECTOR
                 1977 NUMBER OF UNITS (INSTALLED  CAPACITY  MW)
Equipment
Type
Water-tube
Watertube
Total
Firetube
Firetube
Total
Cast Iron
Cast Iron
Total
All Equip-
ment Types
Size Range MW
(106 Btu)
<0.1 (0.4)
0.1-0.4
(0.4-1.5)
0.4-2.9
(1.5-10)
<0.1-2.9
(04-1.0)
<0.1 (0.4)
0.1-0.4
(0.4-1.5)
0.4-2.9
(1.5-10)
<0.1-2.9
(0.4-10)
£0.1 (0.4)
0.1-0.4
(0.4-1.5)
0.4-2.9
(1.5-10)
<0.1-2.9
(0.4-10)
<0.1-2.9
(0.4-10)
Stoker
Coal
—
168
(50)
515
(785)
683
(835)
—
5,768
(1,690)
2,344
(3,956)
8,112
(5,650)
22,657
(1,200)
9,352
(2,460)
3,956
(2,670)
35,965
(6,330)
44,760
(12,815)
Residual
Oil3
—
774
(270)
2,443
(3,670)
3,217
(3,940)
—
30,536
(8,960)
16,348
(26,320)
46,884
(35,280)
40,714
(3,020)
14,323
(3,220)
4,857
(4,540)
59,894
(10,780)
109,995
(50,000)
Distillate
Oil*
—
1,376
(480)
1,775
(2,080)
3,151
(2,560)
—
14,190
(4,160)
8,453
(13,610)
22,643
(17,770)
25,567
(1,880)
8,996
(2,020)
3,049
(2,840)
37,612
(6,740)
63,406
(27,070)
Natural
Gas3
--
1,521
(540)
2,893
(3,935)
4,414
(4,475)
--
52,594
(15,420)
26,862
(43,700)
79,456
(59,120)
105,258
(7,740)
43,764
(10,080)
12,805
(10,900)
161,827
(28,720)
245,697
(92,315)
Total
--
3,839
(1,340)
7,626
(10,470)
11,465
(11,810)
—
103,088
(30,230)
54,007
(87,590)
157,095
(117,820)
194,196
(13,840)
76,435
(17,780)
24,667
(20,950)
295,298
(52,570)
463,858
(182,200)
aA number of boilers have dual  gas/oil  firing capability.   Units  are
 listed here by the primary fuel  burned.
                                  3-9

-------
7.3 percent of all  commercial units below 2.9 MW (10 x 10  Btu/hr) heat
input capacity.  In the industrial sector (Table 3-5), cast iron boilers
account for 64 percent of all boilers less than 2.9 MW, while firetubes
account for 34 percent.  The total 1977 installed heat input capacity of
steam and hot water boilers from Tables 3-4 and 3-5 is summarized in
Table 3-6.  Nearly half of the capacity is provided by natural gas-fired
units.  Residual oil accounts for nearly one-fourth the capacity and is
the second most common fuel used.
       The burner assembly of most gas- and oil-fired equipment normally
consists of the single power burner designs.  However, there are some
atmospheric type gas burners installed on the small size equipment such as
small cast iron boilers.  The majority of the stoker coal units are
underfed.
3.2    FURNACE DESIGN PRACTICE
       This section reviews the current design practice of units
identified in the previous section.  Central air and hot water units are
discussed in the residential section.  For the commercial sector, the
various hot water and steam boiler designs as well  as some warm air
cabinet, rooftop and duct heaters are discussed.
3.2.1  Residential  Units
       The primary space heating systems in use today include gas- and
oil-fired warm air central furnaces, and gas- and oil-fired hot water or
steam units, also referred to as hydronic systems.   Additionally, the
residential sector also includes a great number of  smaller floor, room and
direct vent heater designs, usually gas-fired.  The  combustion systems on
these units are very similar to the gas-fired warm  air furnaces.
3.2.1.1  Gas-Fired Central Air Furnaces
       Figures 3-2 and 3-3 show typical gas-fired forced central air
furnaces which account for the single largest equipment category*.  There
are three basic forced air configurations; "high-boy" (up-flow or
down-flow), "lo-boy" and horizontal.  Typically, for an upflow unit the
*In the past, there were also a considerable number of gravity or natural
 draft gas-and oil-fired central air systems.  These have fallen out of
 favor due to the rather large ducts and furnace volume required and the
 higher cost.
                                    3-10

-------
TABLE 3-6.  SUMMARY OF INSTALLED CAPACITIES OF COMMERCIAL AND INDUSTRIAL
            STEAM AND HOT WATER UNITS WITH HEAT INPUT LESS THAN 2.9 MW
            (10 x 106 Btu/hr) -- MW (PERCENT)
Equipment
Type
Watertube
Firetube
Cast Iron
Total
Stoker
Coal
1,900
(0.41)
14,420
(3.18)
31,590
(6.97)
47,910
(10.6)
Residual
Oila
5,240
(1.14)
48,200
(10.62)
53,790
(11-9)
107,230
(23.7)
Distillate
Oil3
4,490
(0.99)
31,530
(6.96)
33,730
(7.44)
69,750
(15.4)
Natural
Gasa
5,770
(1.27)
79,090
(17.5)
143,520
(31.7)
228,380
(50.4)
Total
17,400
(3.8)
173,240
(38.2)
262,630
(57.9)
453,270
(100)
aBoilers  are  listed by the primary fuel burned.  A large number of
 units have dual  gas/oil fuel burning capability.
                                   3-11

-------
(£-£ aDuaja^ay)  saoeuun^ uie paauo^ pa.nj.-se9   -g-j;
                                                                                        co
                                                                                        r—

                                                                                        ro

-------
CO
 I
  UNIVERSAL SLOTTED PORT STEEL
  BURNER
  Burns Natural And Liquefied Petroleum
  Gases.  Stainless Steel Head,

                                                      HEAT EXCHANGER
                                                                                              UNIQUE PATENTED DRAFT DIVERTER
                                      Figure  3-3.
Gas-fired forced air  downflow furnace and
details of components  (Reference 3-3).

-------
recirculating room air enters the bottom or side of the unit, flows
through the main circulating fan, then to the heat exchanger and usually
out the top to the distribution ducting.  The gas burners are usually
naturally aspirated consisting of venturi three to five primary air
shutter and burner ports  (single port, ribbon or drilled or formed
multiport).  The primary  air is drawn into the venturi by the expanding
natural gas and premixes  with the gas prior to ignition.  The primary
air/fuel ratio can be controlled through the shutter valves at each
venturi.  After the mixture exits the ports it is ignited by a standing
gas pilot or electronic ignitor.  Secondary air to complete the combustion
reaction enters from the  furnace through its secondary air openings and
passes around the burners to complete the combustion reaction.  The
combustion products flow  upward through a parallel flow heat exchanger and
exit  into a collector box or draft diverter.  The draft diverters dilute
the flue gas stream, prevent downdrafts from blowing out the pilot, and
isolate the burner from changes in vent draft.  Typical operating
conditions are listed in  Table 3-7.
       Several comments concerning the data of Table 3-7 should be noted.
The wide range in excess  air levels  is due to variations in installation
and meterological conditions.  The combustion chamber pressures are quite
low due to the naturally  aspirated design.  Consequently, the flue gas
flow  area is quite large  to avoid excessive pressure drop.  The low
velocity associated with  this area results in a fairly low hot side heat
transfer coefficient and  consequently fairly large surface areas.  The
furnace relies on the stack to create sufficient draft to draw the
secondary air through the furnace.   Manufacturers design practice shows
that  stack temperatures below 422 K  (300°F) can yield insufficient draft
for the burners and cause condensation in the stack.
3.2.1.2  Oil-Fired Central Air Furnaces
       Figure 3-4 shows three common oil-fired forced air furnaces.  From
the outside these furnaces appear very similar to the gas-fired units and
-are now being made with overall volumes comparable to gas-fired units.
The main difference between the two  furnace types is burner design.  Most
oil-fired burners use pressurized combustion air which mixes with atomized
distillate oil as it leaves the nozzle.  The gun type oil burner, pictured
in Figure 3-5, consists of a combustion air blower, motor, damper, fuel

                                     3-17

-------
         TABLE 3-7.  TYPICAL OPERATING CONDITIONS FOR A WARM AIR
                     GAS-FIRED FURNACE:  29.3 kW (100,000 Btu/hr)a
 Recirculating Air Flowrate 0.38-0.57 W/m3/s (800-1200 SCFM)

 Combustion Excess Air:  40-120%

 Flue Exit Diameter:  0.089-0.13 m (3.5-5.0 in)

 Heat Exchanger Area:  1.9-2.4 m2 (20-25 ft2)

 Overall Heat Transfer Coefficient:   11-17 W/m2-K
 (2-3 Btu/hr-ft2-°F)

 Exit Flue Gas Temperature (Before Draft Diverter):  505-616 K
 (450-6500p)

 Draft Diverter Dilution Air Flow Percent of Flue:  20-50%

 Combustion Chamber Pressure:   +50 Pa (_+ 0.2 in. H20)

 Temperature Rise on Air Side:  39-55 K (70-100°F)

 Overall Steady State Efficiency:15  75-80%
aData is compiled from discusion with manufacturers and from References
 3-4, 3-5,  3-6,  3-7, and 3-8.
bNew furnace must meet American  National  Standards Institute (ANSI)
 standards  of 75 percent.
                                   3-18

-------
00
I
                              Figure  3-4.   Oil-fired  central  air  furnaces  (Reference 3-3)

-------

Figure 3-5.
Typical high pressure atomizing gun oil burners
(Reference 3-3).
                            3-21

-------
pump, ignition system, main air tube and swirlers, or retention head and
fuel nozzle(s).  The fuel flowrate is controlled by the size of the
orifice in the oil nozzle, while the total air flowrate is controlled by
the blower and damper.  The proper air/fuel ratio is adjusted using the
damper until minimum CO and smoke levels are achieved.  Typical operating
conditions of oil-fired residential furnaces are summarized in Table 3-8.
       The burner  is usually mounted in a refractory or refractory felt
lined combustion chamber which  is cooled by the recirculating room air.
From the combustion chamber the flue gases pass through a gas-to-air heat
exchanger and finally  out the stack.  Generally there is no draft diverter
in the flue because a  forced draft system is used and there is no pilot
flame.  The burner blower may supply the full pressure to exhaust the flue
from the stack or  it may rely partially on the buoyancy forces downstream
of the furnace.
       In recent years the flame retention head burner has become the
primary burner design  sold.  Several types are available with residential
burner manufacturers.  One design is shown in Figure 3-6.  These units
usually produce a  more stable,  compact, and intense flame and will stay in
tune (low CO and smoke) longer  than previous conventional designs.  This
flame retention head produces a stable flame by forming recirculation
zones in the wake  of the flame  retention plate.  Some swirl is also
imparted to the airflow with some burner designs.  Oil spray nozzles are
pressure atomized  often producing a hollow or solid cone spray with a
spray angle from 50 to 80 degrees depending on the burner and firebox
design.  Tuning for low emissions and high efficiency consists of cleaning
the burner and nozzle  of any deposits (or replacing the nozzle), adjusting
the spark ignitors for optimum  spark, and adjusting the air damper for
minimum CO, smoke  and  excess air.
       The design  of the oil-fired burner and heating system is quite
empirical and relies on prototype development, experience and testing.
Efficiency and standards for construction are set by Underwriters
-Laboratory and the American National Standards Institute (ANSI).
3.2.1.3  Gas-Fired Hot Water Units
       Figure 3-7  shows a typical gas-fired hot water or hydronic heater.
New units are usually more expensive than forced air systems and therefore
are now being made in  the larger capacities of 0.38 MW (130,000 Btu/hr)

                                    3-23

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    TABLE 3-8.  TYPICAL OPERATING CONDITIONS FOR OIL-FIRED CENTRAL
                AIR SYSTEMS: 29.3 kW (100,000 Btu/hr)
                      Typical Operating Conditions
Recirculating Air Flow:  0.38-0.57 Nm3/s (800-1200 SCFM)
Combustion Excess Air:  50-85%
Flue Exit Diameter:  0.13-0.18 m (5.0-7.0 in)
Heat Exchanger Area:  1.9-2.8 m2 (20-30 ft2)
Overall Heat Transfer Coefficient:  11-17 W/m2-K
(2-3 Btu/hr-ft2-°p)
Exit Flue Gas Temperature:  533-589 K (500-600°F)
Combustion Chamber Pressure:  12.5-50 Pa (0.05-0.2 in H20)
Temperature Rise on Air Side:  42-44 K (75-80°F)
Overall Steady Efficiency:  75-80%
                                  3-24

-------
                                                    ELECTRODES
                    AIR TUBE
                                                                    CHOKE
Figure  3-6.   ABC Mite  burner with flame retention  head (Reference  3-9)
                                    3-25

-------
                   galvanized and baked
                       ename! jacketi
  massive bronze headers—
      easily removable
comer sealed & interlocked
   combustion chamber
     high velocity water flow
                                                     100% copper
                                                  and bronze waterways
        heat exchanger
        inspection panel
                                                                  baffles
                                                                   1" integral-finned
                                                                     copper tubing
                                                                   modulating valve
              totally enclosed
            automatic controls
removable door for access to
  slide out burner drawer
                               'precision titanium-
                              stainless steel burners
                                                        . '.'if-, '•'•'. ••
        Figure 3-7.    Gas-fired  hydronic boiler  (Reference 3-3)
                                       3-27

-------
 and  above.   However,  old  residential  units  are  still  quite prevalent  in
 the  Northeastern  and  Northcentral  regions of  the U.S.  The gas systems on
 the  new  units  are quite similar  to the  central  air furnace utilizing  the
 naturally aspirated burners.   Heat transfer area is governed by the gas
 side transfer  coefficient which  is once again limited by the pressure drop
 requirements of the naturally  aspirated burners.  Typical operating and
 design conditions for both oil and gas  systems  are given in Table 3-9.
 3.2.1.4  Oil-Fired Hot Water Units
       Figure  3-8 shows the oil-fired hot water system.  Again, although
 quite prevalent  in older  homes in  the Northeast and Northcentral States,
 they are generally more costly than warm air  systems  and are often
 manufactured in  larger size ranges for  new  sales.  These units are similar
 in some  respects  to the oil-fired  warm  air  central furnaces in that they
 often employ a refractory lined  combustion  chamber followed by the heat
 exchange surface.
 3.2.1.5  Stoker Coal-Fired Hot Water  and Warm Air Units
       Most  of the few existing  stoker  coal-fired residential systems are
 underfed stoker units. A typical  stoker is pictured  in Figure 3-9.  The
 coal feed tube delivers the coal to the combustion chamber and also
 supplies the combustion air.   At the  end of the feed  screw, the coal
 enters a cast  iron chamber or  retort  where  the  coal is devolatized.  The
 retort is surrounded  by a wind box that supplies combustion air to the
 fuel bed through  slotted  holes called tuyeres.  In some units, the tuyeres
 rotate to help break  up clinkers and  push ash to the  outside.  Air is
 supplied by  the combustion air blower located under the coal hopper.  The
 airflow  is controlled by  a damper  on  the inlet  or outlet of the combustion
 air  fan. Ash  and clinkers are periodically removed from the outer edge of
 the  fuel bed with a shovel. This  material  raises to  the surface as the
 coal is  fed  from  underneath the  bed.  The best  coal type for a given
 design depends on the design of  the firebox,  retort and air tuyeres.
 Frequently,  a  given furnace is adopted  to only  a limited range of coal
."types.
       The combustion gases pass upward either  to water circulating
 through  a boiler  or to a  heat  exchanger to  heat recirculated room air.
 These  heat exchanger  designs are similar to those used with oil or gas
                                     3-29

-------
 TABLE 3-9.  TYPICAL OPERATING CONDITIONS FOR OIL- AND GAS-FIRED HOT
             WATER BOILER WITH 29.3 kW (100,000 Btu/hr) HEAT INPUT
                                                    Gas          Oil

Recirculating Water Flows, m3/hr (gpm):           0.68-3.4     0.68-3.4
                                                  (3-15)       (3-15)

Excess Air, percent:                              20-100       30-100

Flue Exit Diameter, m (inches):                   0.09-0.13    0.09-0.13
                                                  (3.5-5)      (3.5-5)

Exit Flue Gas Temp, K (°F)                        505-588      477-588
Upsteam Draft Diverter:                           (450-600)    (400-600)

Exit Flue Gas Temp, K (°F)                        422-477      422-477
(Downstream Draft Diverter):                      (300-400)    (300-400)

Combustion Chamber Pressure,  Pa  (in H20):          12.5-50        50
                                                 (0.05-0.2)      (0.2)

Temperature Rise on Water Side,  K (°F)             5.6-22       5.6-22
                                                  (10-40)      (10-40)

Overall Steady State Efficiency, percent:           75-80        75-80
                                 3-30

-------
HYDRO-WALL DESIGN
                                   TOP CLEAN-OUT OPENINGS
      Figure 3-8.  Oil-fired hydronic system  (Reference 3-3)
                                3-31

-------
                              TOP VIEW
                              SIDE VIEW
           1. HOPPER
           2. ELECTRIC MOTOR
           3. TRANSMISSION
           4. COAL FEED TUBE
           5. FEED WORM
6. RETORT
7. RETORT AIR CHAMBER
8. COMBUSTION CHAMBER
9. WIND BOX AND TUYERES
Figure 3-9.   Residential  heater  stoker  assembly  (Reference  3-10),
                                   3-33

-------
except the combustion gas velocities are lower via larger exchange surface
spacing to prevent accumulation of ash.
       Both the warm air or hot water systems use a barometric damper to
control draft through the fuel bed.  When the stack is at negative
pressure the barometric damper allows room air to enter the exhaust
stack.  From an emission perspective this is beneficial because the
naturally induced air entering the stack dilutes the stack CO and unburned
hydrocarbons which occur during transient operation.
3.2.2  Commercial Systems
       The major commercial sources include gas-fired warm air systems and
gas-, oil-, and coal-fired hot water or steam systems.  As noted earlier
some hot water and steam systems are also used for industrial process
steam.  The sections that follow review the current design practice for
the types of units that are most popular in the commercial sector.
3.2.2.1  Warm Air Heaters
       The four major types of warm air heating systems in the commercial
sector are:
       t   Packaged units
       «   Rooftop units packaged as part of central air conditioning
       e   Duct heaters which are also generally part of a central air
           conditioning system
       •   Unit heaters
The packaged type units are scaled-up versions of the residential system.
They include the burner and controls, gas to air heat exchanger, air
circulation fan, draft diverter and cabinet.  There is no appreciable
difference in the burner design and operation other than there may be more
flue gas distribution tubes for better heat transfer.
       Rooftop heaters use either the atmospheric gas-fired combustion
system or a power gas- or oil-fired burner.  The atmospheric gas burners
are identical to the burners used in residential systems-incorporating the
primary air venturi, gas distribution tubes and a gas to air heat
exchanger.  Power or pressurized burners in the rooftop units are either
gas- or oil-fired.  The gas burner is forced draft with a combustion air
blower, spark ignitor, fuel delivery system, and some sort of flame
retention device.  The gas burner will usually fire into a large
cylindrical steel combustion chamber and the combustion gases pass through

                                    3-34

-------
a tubular heat exchanger.   In this case a draft diverter is not used.  In
other power burner designs  the fuel and air is premixed and distributed to
a number of exit  ports  in ceramic blocks.  These ceramic blocks act as
flame holders radiating heat to the heat exchanger surface.  Little
information is available on the emission characteristics or the population
distribution of these commercial systems, especially in relation to the
variety of burner designs just described.
       The third  class  of commercial space heating system is the duct
heater.  These are of two classes -- direct fired and indirect fired.  The
indirect fired units are placed in line in an air conditioning duct.  The
majority of duct  furnaces are naturally aspirated gas-fired units similar
in design to warm air furnaces.  The direct fired duct heater or make-up
air  heater as shown in  Figure 3-10 usually includes the air fan that
supplies a portion of the total air for a commercial building.  These are
exclusively natural gas-fired units and the products of combustion are
combined with the air circulated to the space being heated.  The burners
are  unique in that they are placed in  the delivery air duct and the total
room air supply passes  through the burners.  The hole pattern in the
burner  assembly allows  for  a slow mixing of this diluent air thus
preventing rapid  quenching  of the flame and high CO levels.
       The unit heater  is a variation  of the indirect fired duct heater.
Unit heaters are  self contained systems with a fan, burner and heat
exchanger.  They  usually are mounted from the ceiling to supply warm air
only to the room  in which they are located.  These heaters, although
usually gas-fired, may  also be propane or oil-fired.  One type of unit
heater design, usually  natural gas-fired, operates by heating ceramic
elements which in turn  radiate in the  infrared wavelength range to the
object or area being heated.  This type of heater is frequently used where
a very localized  area requires heating.  In the gas-fired unit the
combustion takes  place  at the surface  of the ceramic tile.  All the
combustion air is aspirated by the gas expansion similar to warm air
-furnace burners.  No combustion air blower or air circulating fan is
required.  The combustion products exit directly into the room but
pollutant levels  are quite  low because of nearly complete combustion at
the  ceramic tile.
                                    3-35

-------
                                                Airflow Line
                                                   Burner
      FAN
                                               HEATH) AIR
Figure 3-10.
Direct gas-fired duct heater  and  line burner assembly
(Reference 3-11).
                                 3-36

-------
3.2.2.2  Hot Water or Steam Systems
       In the size range of 0.1 to 2.9 MW (0.4 to 10 x 106 Btu/hr) there
are over 10 different boiler designs adapted to be either gas- or, oil-,
or coal-fired.  These designs can be grouped in three major categories:
watertube, firetubes, and cast  iron boilers.  Figures 3-11 and 3-12 show
schematics of watertube and firetube designs, respectively.  Cast iron
hydronic designs  are described  in Section 3.3.1.3 for residential hot
water units; commercial or industrial cast iron units are of similar
design.  Both commercial watertube and firetube designs are similar to the
small industrial  size boiler designs which are assessed in another NO
                                                                     /\
EA report  (Reference 3-12).  However, a brief description of firetube and
cast iron boilers, which represent over 95 percent of the installed
conmercial hot  water or steam capacity, is given.  There are four major
firetube boiler designs — scotch, horizontal return tube (HRT), firebox,
and vertical.
Scotch Firetube
       This boiler design, developed over 30 years ago is the most popular
of the firetube boilers.  Scotch firetube boilers are available in two-,
three-, or four pass units with the boiler and furnace contained in the
same shell.  The  heat input capacity for these units is normally less than
2.9 MW (10 x 10  Btu/hr).  They account for almost 40 percent of total
firetube capacity in this size  range, and can burn a variety of fossil
fuels.  However,  coal-fired units are not common because of slagging and
scaling problems.
Horizontal Return Tubular (HRT)
       The HRT  boiler and furnace is generally lined with brick.  The
boiler, which is  set horizontally, rests above the refractory brick
furnace.  The HRT design accounts for about 11 percent of the installed
capacity in the size category less than 2.9 MW (10 x 10  Btu/hr).  The
boiler comes with two-, three-, or four-passes and can burn all types of
fossil fuels.   Coal is burned on a grate.
.Firebox
       The firebox  design employs two- or three-passes depending on
whether the boiler is the short or compact type.  Similar to the Scotch
design, the furnace is steel encased, water jacketed, and internal to the
                                    3-37

-------
        -FURNACE
                           TO   >
                       ATMOSPHERE
                              STACK
                                                              STEAM
                         ,\X"WV
                          7LAME
                                   WATER AND STEAM
                                                         BOILER
                                       WATER
Figure 3-11.   Simplified  diagram  of  a watertube boiler (Reference 3-2)
                              TO
                           ATMOSPHERE
                                                 STEAM OUT
 Figure 3-12.   Simplified diagram of a firetube boiler (Reference 3-2),
                                 3-38

-------
boiler.  Firebox  units are designed with heat input capacities as high as
5.8 MW (20 x 10  Btu/hr) and have an advantage of compactness and high
efficiency.  Below 2.9 MW (10 x 106 Btu/hr) they account for almost 45
percent of the total installed firetube capacity.
Vertical
       With the vertical design, the firetubes are vertical instead of
horizontal as with the other designs.  The tubes can be either submerged
in water or partially exposed to steam.  Figure 3-13 shows the partially
exposed tube design.  Submerged tube designs have been abandoned because
of their tendency to leak.  Capacities of these units are generally lower
than 0.75 MW (2.5 x 10  Btu/hr) and have a maximum efficiency of about
70 percent (Reference 3-2).  These units comprise less than 5 percent of
total firetube capacity.
       Coal-fired systems in the size category below 2.9 MW (10 x 105
Btu/hr) are all stoker or hand fed.  Three designs of watertube and
firetube coal-fired stokers, are in use -- underfed, overfed, and spreader
stokers.  Underfed stokers, account for about 80 percent of coal-fired
boilers with heat input below 2.9 MW (10 x 106 Btu/hr).  These units
feed raw coal from below the fuel bed.  Overfeed stokers account for
approximately 10 percent of coal-fired boiler capacity.  They are less
popular because of higher cost, which is about twice that of an underfeed
stoker unit.  Spreader stokers account for less than 10 percent of the
capacity in the commercial size range.  The coal in the spreader stoker
burns partially in suspension.  Combustion is completed on a moving or
stationary vibrating grate.  Further details on the stoker designs are
given in the NO  EA report on industrial boilers (Reference 3-12).
               A
3.2.2.3  Cast Iron
       The commercial cast iron boiler consists of an assembly of cast
iron sections with water or steam on one side and combustion gases on the
other.  Frequently the cast iron surface is either ribbed or studded to
provide extended heat transfer surface area.  The size of the boiler is
determined by the number of sections sandwiched together.  Although these
units are more expensive than firetube boilers, they are also more
reliable, durable, and require less maintenance.  As with residential
units they are usually naturally aspirated when fired with gas, or fitted
with a gun type oil  burner.

                                    3-39

-------
        Figure 3-13.  Exposed-tube vertical  boiler (Reference 3-2).

       With a gas-fired unit the entire bottom of the boiler is  open to
allow combustion air to be drawn into the unit by the draft of the flue
gases.  With oil firing, a firebox cavity is built into the unit and the
system is intended to be sealed.  Design and construction of these units
are governed by ASME Boiler Code for pressurized  vessels and are tested
and rated by the Hydronics Institute.  The Hydronics  Institute provides an
Industrial Boiler Rating (IBR) in accordance with minimum efficiency,
percent CCL, flue gas temperature, and smoke emissions.
3.3    AREAS OF ENVIRONMENTAL CONCERN
       This section identifies areas of environmental concern for the
residential, commercial and industrial combustion equipment types with
heat input capacities of 0.1 to 2.9 MW (0.4-10 x  106  Btu/hr).  Major
pollution streams identified here are then quantified in Section 4.
Table 3-10 sunmarizes pollution streams from these combustion units.  As
indicated, combustion products exiting the stack  constitute the major
environmental concern for all equipment types.  For coal-fired equipment,
ash disposal is also an area of environmental concern due to quantities of
ash generated and some potentially toxic constituents in the ash.  Leakage

                                    3-40

-------
             TABLE  3-10.    EMISSION  STREAMS  FROM  RESIDENTIAL  AND  COMMERCIAL  UNITS
  Emission Streams
                                  Gas- and 01l-F1red Systems
                          Residential  Commercial
Residential  Residential  & Commercial  Hot Water
 Warm A1r     Hot Water   Direct Fired  and Steam
  Furnace       Heater        Heater     Boilers
                                                    Coal- and Wood-Fired Systems
Residential
 Warm Air
  Furnace
            Commercial
Residential  Hot Water
 Hot Water   and Steam
  Heater      Boiler
                                                                                                                    Remarks
Combustion products
from the stack
                                                                                      Major pollutants 1n  the flue
                                                                                      gas  Include NOX, HC,  and
                                                                                      CO.  In addition,  part leu late
                                                                                      (smoke) and SOX when
                                                                                      burning oil or coal.
Combustion products
leakage Into heated
air
                                                                                     Combustion products  leakage
                                                                                     across heat exchanger with
                                                                                     some older units.  Some
                                                                                     leakage from ducts into
                                                                                     surrounding space also
                                                                                     possible.
Solid ash waste
disposal
                                                                                     Ash wastes to disposal site.
                                                                                     Potentially Teachable trace
                                                                                     elements In the  ash.  Major
                                                                                     concern with coal.
Combustion  products
mixed with  heated
air
                                                                                     Direct fired heaters are
                                                                                     primarily gas fired.  Major
                                                                                     pollutants are NO,, CO,
                                                                                     and HC.
Fuel Supply
leakage
                                                                                     Leakage of gas  and oil only
                                                                                     an accidental occurrence.
                                                                                     Coal dust as fugitive
                                                                                     emissions.
M — major  pollutant stream
m — minor  pollutant stream.

-------
of combustion products into habitated areas may occasionally cause
environmental concern with some older units.  These three streams — stack
emission, combustion products leakage, and solid waste -- are briefly
discussed below.
3.3.1  Stack Emissions
       Pollutant emission of NO ,  CO, and unburned hydrocarbons (UHC) in
                               A
varying concentrations are emitted from the stack along with H^O, C02,
N2, and oxygen for all fuels burned.  Levels of sulfur and inorganic
compounds, negligible with natural gas and distillate oil combustion, are
significant when residual oil and  coal are burned.  Sulfur and ash in the
residual oil and coal convert to S02 emissions and particulate matter
respectively and exit with the flue gas.  Air pollutant emissions from
coal are often emitted in greater quantity than emissions from gas and oil
combustion.  Conversion of fuel bound nitrogen in the coal contributes to
emissions of NO , which are generally higher than those of units fired
               A
with gas or oil.  Also carbon monoxide as well as nonmethane hydrocarbon
emissions from coal are often higher than those from gas and oil
combustion.
       The largest emission levels of CO, UHC, and smoke occur during
lightoff and shutdown periods.  Because of the cyclic nature of most
heating systems, the furnace often never reaches equilibrium condition.
The CO, UHC, and smoke problem associated with cyclic operation is further
aggravated when the system is oversized.  In such cases, cycle frequency
is usually higher with a correspondingly low on-period.
3.3.2  Leakage of Combustion Products
       Leakage of the combustion products into the heated space may occur
in a number of areas in the furnace system.  Of primary importance is the
possibility of leakage across the heat exchanger of a warm air furnace.
Many gas utilities will shut off the gas supply to a unit that has visible
cracks in the heat exchanger.  Overall, unless residential heating
equipment is relatively old, leaks are not a serious environmental concern.
       In a home installation the house air is usually recirculated from
the rooms to the furnace and back  to the rooms.  If there is leakage from
the furnace system potentially the air quality in the rooms would
deteriorate.  However, usually there is sufficient make-up air in
buildings through leaks in windows, doors, etc., to prevent this problem.

                                    3-42

-------
As greater emphasis is given to energy conservation and the sealing of
leaks into the house (air infiltration accounts for the largest load in
residential heating) attention should be paid to the air quality within
the home.  Sufficient air must always be brought into the home for the
combustion process.  In commercial systems frequently make-up air is
brought into a building so that a certain number of ambient air changes
per hour is maintained.  Some commercial heating systems also rely on an
outside air supply for combustion.
3.3.3  Solid Waste Streams
       The solid waste stream (although intermittent) in the form of
bottom ash clinkers is of environmental concern for coal-fired residential
and commercial size units.  These clinkers usually find their way to a
refuse disposal site in urban areas where trace contaminants in the ash
can be leached out by rainfall.   In rural areas they are usually buried or
disposed  in a local waste disposal site where leaking can also occur.
                                     3-43

-------
                          REFERENCES FOR SECTION 3
3-1-    "General  Housing Characteristics for the United States and Regions;
       1976," U.S.  Department of Commerce,  Bureau of Census,  Current
       Housing Reports, Series H-150-76, Part A,  U.S.  G.P.O.  Washington,
       D.C. 1978.

3-2.    Devitt, T.  et al.,  "The Population and Characteristics of
       Industrial/Commercial  Boilers," EPA 600/7-79-178a,
       NTIS-PB-80-150881,  August 1979.

3-3.    Brown, R. A., et al..  "Feasibility of a Heat and Emission Loss
       Prevention System for  Area Source Emissions," EPA-600/2-76-097,
       NTIS-PB 253 945, April 1976.

3-4.    "Gas Engineers Handbook," American Gas Association, Industrial
       Press Inc.,  New York,  NY, 1969.

3-5.    "1972 ASHRAE Handbook  of Fundamentals," American Society of
       Heating,  Refrigerating, and Air-Conditioning Engineers Inc., New
       York, NY, 1972.

3-6.    "1972 Equipment Volume/ASHRAE Guide and Data Book," American
       Society of Heating, Refrigerating and Air-Conditioning Engineers
       Inc., New York, NY, 1972.

3-7.    Strock, C.,  and R.  L.  Koral,  "Handbook of Air Conditioning,
       Heating,  and Ventilating," Industrial Press Inc., New York, NY,
       Third Edition, 1965.

3-8.    "Research on Effect of Ambient Pressures in Combustion Chambers of
       Contemporary Appliances on Primary Air Injection and Oth.er Gas
       Burner Operating Conditions," American Gas Association Committee on
       Domestic Gas Research, Research Report No. 1080, Arlington, VA,
       June 1947.

3-9.    Hall, R.  E., et al.. "A Study of Air Pollutant from Residential
       Heating Systems," EPA-650/2-74-003, NTIS-PB 229 697, January  1974.

3-10.  "Domestic Stokers,  Hopper and Bin Feed by Will-Burt," Manufacturer
       Brochure.  Form W346-75-2M, The Will-Burt Co., Orrville,  OH,  1975.

3-11.  "Maxon -- Burner Equipment and Valves for Industry," Manufacturer
       Brochure, Maxon Premix Burner Company, Inc., Muncie,  Indiana,
       August 1969.

3-12.  Urn, K. J. et  al.,  "Industrial Boiler Combustion Modification  NOX
       Control:  Volume I.  Environmental Assessment."  EPA-600/7-81-126a,
       July 1981.
                                    3-44

-------
                                 SECTION 4
           CHARACTERIZATION OF FUELS, PRODUCTS AND AIR EMISSIONS

       This section surmiarizes the physical and chemical  characteristics
of fuels burned and waste streams (primarily flue gas) for residential  and
commercial heating systems described in Section 3.  A recent air pollutant
emission inventory is also presented for selected systems.
4.1    SUMMARY OF SAMPLING AND ANALYTICAL ACTIVITIES
       Activities to quantify air pollution emissions and determine
control potential in residential/commercial heating have centered
primarily on residential heating furnaces and commercial  steam and hot
water units.  Less is known of the emissions of various commercial warm
air heating systems.
       Table 4-1 surmiarizes major laboratory and field studies performed
on residential and commercial heating equipment.  The table lists the
specific type of equipment tested, the organization performing and
sponsoring the work, the completion date of the study and the principal
pollutants sampled.  Information on the emission controls investigated  is
also listed.  Major results of these studies will be reviewed in the
following sections of this report.
       As the table indicates, the bulk of the sampling and analytical
activity for the gas-fired residential and commercial space heaters and
boilers has been sponsored by the EPA and by the American Gas Association
Laboratories (AGAL).  Some work specific to oil-fired systems has been
jointly sponsored by the American Petroleum Institute (API) and the EPA.
Tests primarily related to energy consumption and conservation (with
limited emission data taken) were not included in this table.  These tests
have been performed for the National Science Foundation (NSF), Federal
Energy Administration (FEA), and the Department of Energy (DOE).
                                    4-1

-------
                                TABLE  4-1.   SUWARY  OF  MAJOR SAMPLING  AND  ANALYTICAL ACTIVITIES
                                                ON  RESIDENTIAL  AND  COMMERCIAL  HEATING SYSTEMS
-£»
I

General
Equipment
Category


Gas -Fired
Indirect Heating





















Specific*
Equipment
Tested


SFB, FFB, FAF

FAF




HUB

FAF


FAF, HWB, VH
USH, HH





FAF, CIB, SFB,
FFB, WB



Organ ization
Performing Work


Battelle
Columbus Labs.
American Gas
Association (AGA)



The Research
Company (TRC)
American Gas
Association (AGA)

American Gas
Association (AGA)





Battelle
Columbus Labs.



Sponsoring
Organization


American Petroleum
Institute (API)
American Gas
Association (AGA)



American Gas
Association (AGA)
Gas Appliance
Manufacturers
Association (GAHA)
American Gas
Association (AGA)





American Petroleum
Institute (API)
and EPA
i

Completion
Date


1971

1975




1974

1978


1974






1973


Emissions FvaluatM



N0x
X

X




X

X


X






X




CO
X

X




X

X

-
X






X




HC
X

X




X




X






X




S0x
X


















X




Part.
X






X











X




Smoke
X


















X



Trace
f, 1 emen t s
























Organ ics






















i

Pollution
Controls


Tuning

Radiant
screens
secondary
air
baffles
None

None


Radiant
screens
secondary
air
baffles
and burner
mods
Tuning,
replace..
burner


Ref .


4-1

4-2




4-3

4-4


4-S






4-6


          •Specific equipment tested

           SFB = Scotch Firetube Boiler
           FFB = Firebox Firetube Boiler
           HWB = Hot Water Boiler
           VH  = Vented Heater
WS  = Wood Stove
USH = Unvented Space Heater
WH  - Wall Heater
WB  = Watertube Boiler
BSFB = Bituminous Stoker Firetube Boiler
FP   = Fireplace
FAF  = Forced Air Furnace
CIB  = Cast iron boiler

-------
                                                                   TABLE  4-1.    Continued
-P.
oo
General
Equipment
Category


Gas-Fired
Indirect Heating
(continued)








Gas-Fired
Direct Heating
Oil-Fired
Indirect Heating





Specific*
Equipment
Tes ted


FAF, HHB



FAF


UVH

FAF, HB, SFB,
FFB
Maxon Makeup Air
Burners
SFB, FFB, FAF
CIB, HWB, HH
FAF, HHB, HH,
SFB, FFB, CIB,
HB



Organization
Performing Work


EPA



Lawrence
Berkeley Labs.,
U.C.
The Research
Corp. (TRC)
TRW

IGT

Battelle
Columbus Labs.
Battelle
Columbus Labs.
-i



Sponsoring
Organization


EPA



ERDA (DOE)


EPA

EPA

Maxon

American Petroleum
Institute (API)
API and EPA





Completion
Date


1974



1976


1974

1979 -
Ongoing
1969

1971

1973




Emissions Evaluated



NO,
X



X


X

X

X

X

X






CO
X



X


X

X

X

X

X






HC
X








X

X

X

X






S°x




X




X



X

X






Part.









X



X

X






Smoke
X








X



X

X





Trace
E 1 emen t •;









X












Organics









X











Pollution
Controls


Burner
and
combust-
tion mods
None


None

None

None

None

Tuning,
Replace-
ment and
burner
mods.


Ref.


4-7



4-8


4-9

4-10
4-11
4-12

4-1

4-6




           *Specific equipment tested

              SFB = Scotch  Firetube Boiler
              FFB * Firebox Firetube Boiler
              HHB = Hot Hater Boiler
              VH  = Vented  Heater
WS  * Hood  Stove
USH = Unvented Space Heater
HH  = Hal I  Heater
HB  = Hatertube Boiler
BSFB =  Bituminous Stoker  Firetube Boiler
FP   =  Fireplace
FAF  =  Forced Air Furnace
CIB  =  Cast  iron boiler

-------
                                                                      TABLE  4-1.   Continued
General
Equipment
Category


Oil-Fired
Indirect Heating
(continued)



















Specific*
Equipment
Tested


FAF. HWB


FAF


HWB

WH, FAF


FAF



FAF



FAF
SFB


Organization
Performing Work


EPA


U.S. Oept. of
H.E.W.

Langley Research
Center
Canadian Combus-
tion Research
Lab. (CCRL)
Rocketdyne Div.
Rockwell Inter-
national

Acurex



EPA



Sponsoring
Organ ization


EPA


NAPCA/EPA


NASA

Canada Centre
for Mineral and
Energy Technology
EPA



EPA



EPA



Completion
Date


1974


1970


1976

1978


1976 to
1979


1979



1975 to
1979

Emissions Evaluated



N0x
X


X




X


X



X



X




CO
X


X




X


X



X



X




HC
X


X







X



X








S0x















X








Part.















X



X




Smoke
X







X


X



X



X



Trace
Elements






X








X








Organics















X



X



Pollution
Controls Ref.


Burner & 4-7
combus-
tion mods.
Flame re-
tention
burner 4-13
None 4-14

Water-oil 4-15
emulsion

Burner & 4-16
furnace 4-17
develop- 4-18
ment 4-19
Low emis- 4-20
sion high
efficiency
furnace
Water- 4-21
oil 4-22
emulsion 4-23
 I
-p>
          *Specific equipment tested

            SFB * Scotch Firetube Boiler
            FFB = Firebox Firetube Boiler
            HUB = Hot Water Boiler
            VH  = Vented Heater
WS  = Wood  Stove
USH = Unvented Space Heater
WH  = Wall  Heater
WB  = Hatertube Boiler
BSFB =  Bituminous Stoker  Firetuhe Boile
FP   =  Fireplace
FAF  =  Forced Air Furnace
CIB  =  Cast  iron boiler

-------
                      TABLE  4-1.   Concluded
General
Equipment
Category


Oil-Hred
Indirect Heating
(continued)


Coal-Fired
Indirect Heating





Wood -Fired
Indirect Heating



Specific*
Equipment
Tes ted


FAF


FAF, KB
SFB, FFB
BSFB

FAF, HWB

FAF, HWB


WS, FP

WS



Organization
Performing Work


EPA


TRW

Battelle
Columbus Labs
Monsanto Research
Corporation
Battelle
Columbus Labs

Monsanto Research
Corporation
Battelle
Columbus Labs


Sponsoring
Organization


EPA


EPA

EPA

EPA

Bituminous Coal
Research (BCR)

EPA

EPA



Completion
Date


1980


1979 to
ongoing
1976

1978

1978


1980

Ongoing


Emissions Evaluated



NOX
X


X

X

X




X

X




CO
X


X

X

X




X

X




HC
X


X



X




X

X




S°x
X


X

X

X




X

X




Part.
X


X

X

X




X

X




Smoke
X


X

X



X








Trace
Elements
X


X



X




X

X




Organ ics
X


X

X

X




X

X



Pollution
Controls


None


None

Coal
Switching
None

Furnace
Develop-
ment
Tuning

Process
Modifi-
cations


Ref.


4-24


4-10
4-11
4-25

4-?6

'4.? 7


4-28

4-29


•Specific equipment tested

  SFB  =  Scotch Firetube  Boiler
  FFB  =  Firebox Firetube  Boiler
  HWB  =  Hot Water Boiler
  VH  =  Vented Heater
WS  = Wood  Stove
USH = Unvented Space Heater
WH  = Hal!  Heater
WB  = Watertube Boiler
BSFB  =  Bituminous Stoker Firetube Boiler
FP   =  Fireplace
FAF   =  Forced Air Furnace
CIS   =  Cast iron boiler

-------
       A large number of the test programs listed in Table 4-1 were
performed under laboratory conditions allowing for the monitoring of many
test parameters.  Carbon monoxide (CO), unburned hydrocarbons (UHC),
NO  , S(L, smoke, and filterable particulate matter were the principal
  X    c
pollutants of interest tested.  Trace metals and organic emissions were
determined primarily with coal and wood combustion.
4.2    FUELS
       Over 90 percent of residential furnaces and small commercial
heaters burn natural gas or distillate oil.  Residual oils which require
heating for efficient atomization and combustion are generally burned in
the larger commercial equipment.  Coal is still used in some residential
furnaces and hot water heaters.  The  increasing scarcity of the cleaner
gas and distillate oil fuels has renewed interest in coal  and wood firing
for residential and commercial applications.  However, economic and
environmental considerations still dictate the use of natural gas or
distillate oil as the primary fuels for the small residential systems.
4.2.1  Gaseous Fuels
       Natural gas is the most common fuel for residential and conmercial
space heating and commercial hot water or steam production.  Approximately
55  percent of the residential and comnercial equipment with heat input
less than 2.9 MW (10 x 106 Btu/hr) is fired with this fuel.  Natural
gas, which is relatively clean burning and easy to handle, is the primary
fuel used for direct fired commercial heaters in which the combustion
products are mixed directly with heated air.  However, some oil-fired
portable direct space heaters are being used commercially mainly for
construction jobs, garages, barns, etc.
       Primary air pollutants emitted from gas-fired units include NO ,
                                                                     /\
CO, and hydrocarbons.  Particulate matter and sulfur oxides are generally
minimal and do not pose an environmental concern.  Other gaseous fuels
used in the residential sector include bottle butane or propane, also
known as liquid petroleum gas (LPG).  Nearly half of domestic LPG
-consumption is for warm air furnaces and steam and hot water hydronic
boilers.
       The continuously rising cost of natural gas may in the future  lead
to  significant use of electric heat or alternate gaseous fuels for
residential and comnercial space heating.  One such alternate fuel is the

                                    4-6

-------
high Btu gas produced from the gasification of coal.   High Btu gas,  also
referred to as synthetic natural gas (SNG), is a pipeline quality gas
essentially identical in composition to natural gas.   Thus, SNG can use
the same distribution and combustion system now being used for natural
gas.  However, at present, there is no commercial high Btu gas plant
supplying pipeline networks carrying natural gas.  The Lurgi methanation
process has been demonstrated to be the most technically feasible of all
high Btu gasification processes.  However, high capital and operating
costs may preclude the commercial availability of this alternate gaseous
fuel until the late  1980's.  In the meanwhile, as natural gas supplies
become increasingly  scarce, it is possible that more industrial users will
be made to switch to alternate fuels to leave sufficient natural gas for
existing residential and commercial heating installations.
4.2.2  Liquid Fuels
       Liquid fuels  for residential heating are almost entirely distillate
oils, while commercial and industrial units in the size range of 0.1 to
2.9 M
oils.
2.9 MW (4 x 105 to 10 x 106 Btu/hr) burn both  distillate and  residual
       There are various grades of fuel oil available today in the United
States.  These oils are classified according to their physical
characteristics as shown in Table 4-2.  Grades No. 1 and No. 2 are
distillate oils while Grades No. 5 through No. 6 are residual oils.  The
table also describes low sulfur residual oil which is a fuel growing in
popularity, especially in  those areas with stringent sulfur emission
regulations.  Grade No. 4  oil can be either a distillate or a mixture of
distillate and residual oil (Reference 4-34).  The No. 2 fuel oil accounts
for about 75 percent of the distillate fuel consumption in residential
heating systems.  The remainder of the domestic oil demand is met with
No. 1 grade oil (Reference 4-35). Residual oil accounts for about
60 percent of all oil burned in commercial and industrial equipment with
heat input less than 2.9 MM (10 x 106 Btu/hr) (Reference 4-36).
       Methanol and water-in-oil emulsions have also been investigated as
alternate liquid fuels for residential and commercial space heating
equipment.  Methanol is currently produced from the synthesis of  natural
gas.  However, there is currently strong interest in methanol generation
                                    4-7

-------
                                      TABLE  4-2.   FUEL OIL DESIGNATION  AND  TYPICAL  CHARACTERISTICS
                                                       (Reference 4-30)
4=.
 I
00
Grade*
No. 1
No. 2
No. 3
No. 4
No. 5 Light
No. 5 Heavy
No. 6
Low-Sulfur
Residb
Description and Application
Light distillate oil Intended for vapori-
zing pot-type burners. Seldom used for
pressure-type oil burners or comnercial
burners.
Medium distillate oil for general pur-
pose domestic and commercial heating
equipment.
Obsolete grade designation.
Heavy distillate oil that may contain
some residual oil. Suitable for firing
most commercial burners.
Light residual oil for commercial-
Industrial burners. Generally contains
a larger blended portion of distillate
oil than No. 5 Heavy. Usually requires
preheat for burning but not for handling.
Medium-viscosity residual fuel oil for
commercial-Industrial burners. Usually
requires preheat for burning.
High-viscosity grade of residual fuel
oil for the largest comnercial-
indjs trial burners with full preheating.
Sometimes referred to as "Bunker S".
Residual fuel oil for commercial-
industrial burners that is refined or
blended to meet local sulfur regulations
Preheating Requirement Viscosity Range
For Pumping
and Handling
No
No
-
Usually
Noc
Usually
Noc
Usually
Noc
Yes
Usually
Noc
For
Burning
No
No
-
Usually
Noc'd
Usually
Yesc
Yes
Yes
Usually
Yesc
Saybolt Universal
at 100°Fe
—
33-38 SSU
(35)
-
45-125 SSU
(80)
125-300 SSU
(200)
300-900 SSU
(550)
900-9000 SSU
(5000)
45-9000 SSU
Typical
API Gravity
Sec. at 60°Ff
42
35
-
19
IB
16
13
~~
                     'Grade numbers No. 1, No.  2, No. 4, No. 5 (light), No. 5 (heavy), and No. 6 are ASTM designations  (Reference 4-31).
                     ''"Low-sulfur resld" is a recent term used to  describe residual  oil grades recently shipped to meet  local regulations;
                      it is essentially replacing No. 5 and No.  6  where sulfur regulations are 1n effect, for example,  along the East
                      Coast.  (The sulfur content of this grade  of fuel oil is generally 1 percent, or less.)  The viscosity of present
                      low-sulfur resid is in the range of No. 5  (Reference 4-32).   (It is not clear what the viscosity  of these fuels
                      may be in the future.)
                     cPreheating requirement depends on pour-point and viscosity in  relation to climate.
                     ^May require heating for burning when using mechanical atomization.
                     eViscosity limits specified by ASTM 0396-75 for number grade  shown.  Range for low-sulfur resid  is  estimated.
                      Average viscosity for U.S. refined fuels from ERDA Heating Oils Survey, 1975 (Reference 4-33) is  shown in brackets
                      and is presented as a typical value.
                     fAverage API gravity for U.S. refined fuels from ERDA Heating Oils Survey, 1975 (Reference 4-33).

-------
from biomass.  Combustion of methanol in an experimental hot wall  furnace
produced approximately 75 percent  less NO  than distillate oil
                                         /\
combustion (Reference 4-37).
       Water-in-oil emulsions have been  investigated as a means to
increase efficiency of residential furnaces as well as to reduce NO
                                                                   ^
emissions.  NO  emission levels from emulsions with approximately
              /\
50 percent water  in distillate oil by mass approached the levels obtained
from methanol combustion (Reference 4-38).  The EPA program also tested
emulsions in one  residential and one commercial unit using three
commercially available water/oil emulsifiers (References 4-21, 4-22, and
4-23).  The laboratory study concluded that NO , smoke and particulate
                                              A
mass are reduced  while CO and HC were not significantly affected using up
to 32 percent water-in-oil  emulsions.  Efficiency dropped sharply when the
percentage of water in the  emulsion exceeded 18 percent.  NO  reductions
                                                            /\
ranged from about 15 to 50  percent depending on the type of emulsifier and
source used.  With water/residual oil emulsion tests, no significant
effects on NO, SOp, HC or CO emissions were reported (References 4-22
and 4-23).  The  little change in NO emissions compared to tests with
distillate oil was attributed to the ineffectiveness of water emulsion in
reducing fuel nitrogen conversion to NO    Particulate mass emissions
                                       «
decreased with increasing percent  water  in the residual oil (up to
30 percent water  in oil was tested)  (Reference 4-22).  However, the total
amount of fine particulate  emissions was found to increase
(Reference 4-23).  Boiler efficiency changes varied from +1 to -7 percent
with excess air levels set  at emission smoke limits for both oil only and
water-in-oil tests (Reference 4-23).
       Recent studies on two residential heating systems showed that over
10 percent water  content in the distillate oil is impractical because  it
leads to increased CO emissions (Reference 4-15).  Furthermore, the
increase in combustion efficiency with 10 percent water content was found
to be modest (less than 2.6 percent).  This slight improvement in
efficiency does not warrant operating difficulties such as ignition
difficulties, pump failures, combustion  instabilities and corrosion of
water-in-oil emulsions (Reference 4-15).  These results agree with EPA
test results.
                                    4-9

-------
4.2.2.1  Physical  Properties
       Viscosity is the primary physical  property of fuel  oils  affecting
equipment operation and emissions.   Viscous  oils, No.  2  distillate and
higher grades need to be atomized  to form small  droplets which  can mix
thoroughly with combustion air and burn efficiently  and  completely.   The
energy required to break up the oil  in  these droplets  depends  on the
surface tension of the oil and the mean diameter of  the  desired droplet.
Viscous residual oils have higher  surface tensions,  thus requiring more
energy to achieve the same degree  of atomization as  a  distillate oil.
This is accomplished by heating the fuel  to  about 350  K  (206°F) for
No. 6 oil prior to atomization.  In burners  designed exclusively for
kerosene and No. 1 distillate oil,  the  oil  is generally  not atomized but
is prepared for burning solely by  vaporization.
       Three main methods of atomization  are used in commercial
boilers — air, pressure and rotary atomization.  Pressure atomization  is
used in about half of all commercial boilers, while  air  and rotary
atomization methods are evenly divided  among the remaining burner types
(Reference 4-6).  Steam atomization, which  is prevalent  with residual oil
combustion, is not common in the small  commercial size boilers.
       The high-pressure atomizing gun  oil  burner is the most widely used
residential heater distillate oil  burner, accounting for over  90 percent
of the total population (Reference 4-6).   Low pressure and vertical  rotary
atomized burners are two other types of distillate oil-fired burners for
residential heating.
       Fuel oil viscosity and atomization methods have a significant
effect on particulate and smoke emissions.   A recent study of  emissions
from commercial hot water and steam boilers  indicated  that combustion of
the heavier, more viscous fuels (i.e.,  lower API gravity)  yielded higher
emissions of smoke and filterable  particulates under baseline  operating
conditions (Reference 4-39), as Figure  4-1 indicates.  The heavier fuels
also tend to have higher ash content, however the ash  was found to be only
partially responsible for the increase  in particulate emissions.
       Heavy viscous oils are also higher in molecular weight  and have  a
lower percentage of hydrogen; they tend to form coke,  especially with
cyclic burner operation.  This characteristic of residual oils  makes for
increased burner maintenance to clean carbon deposits.  Carbon  coking on

                                    4-10

-------
                    12.0
                 £(100)
                  en
                 o
                 o
                 o
0>
to
13
O
•M
S_
D-
O)
JO
J_
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                     9.0
                     (75)
                     6.0
                     (50)
                     3.0
                     (25)
                  No4
                   Fuel Oil Grades
                          No6
                         10   15   20   25   30  35    40
                                 API Gravity

         Figure 4-1.   Effect of  API  gravity on parti oil ate emissions
                      (Reference 4-39).
 the oil  gun tip can  lead to insufficient fuel-air mixing and consequent
 emissions  of particulate and soot.
 4.2.2.2  Chemical  Properties
       Sulfur and  nitrogen  concentrations in the fuel oil affect emissions
 of  SO  and  NO  respectively.  Essentially all  of the sulfur in the
     ^       "
 fuel oil converts  to gaseous SOp and SO., during combustion.  However,
 only 40  to  60 percent of the nitrogen in residual fuel  oil is generally
 converted  to NO  (Reference 4-37).   For low nitrogen content distillate
 oil the  conversion can be as high as 100 percent.  Heavier oils often
"contain  more nitrogen and sulfur than distillate oils,  contributing to
 higher NO   and SO  emission levels.
       Certain constituents (impurities) present in  most fuel oils are
 noncombustible and form residual ash.  Most fuel oil ash results from
                                     4-11

-------
contaminants present in the crude oil,  with a  minor  fraction  due to
contamination occuring during  handling  or  refining.   Heavier  fuels  contain
the most ash.  The composition of fuel  ash,  particularly from residual
oils,  may include trace elements.  Some of these  elements are toxic and
may adhere to aerosols emitted with combustion products.  Distillate No.  2
oil contains very little ash and trace  elements as compared with No.  6
residual oil.  Because residential or commercial  sources have generally
low stack heights, the ground  level concentration of these toxic elements
in the immediate area of a residential  or  commercial  heating  plant  burning
residual oils may be significant.
       In a study by the Langley Research  Center  on  a commercial heating
plant burning residual oil, it was found that  toxic  trace elements, Zn,
Mo, Ag, Pb, and to a lesser extent Cd,  tended  to  concentrate  on  small
aerosols in the inhalable size range (Reference 4-14).   The study
concluded that combustion of residual oils in  commercial heating equipment
could cause toxic element concentration in the vicinity  of the plant to be
above safety levels established by the  National Institute for Occupational
Safety and Health (NIOSH).  Therefore,  either  higher stacks for  improved
dispersion of these aerosols or combustion of  cleaner distillate oils
would be necessary to maintain low ambient trace  element concentration.
4.2.3  Solid Fuels
       Coal and wood are the principal  solid fuels burned in  combustion
equipment with heat input capacity less than 2.9  MW  (10  x 10   Btu/hr).
Coal-fired warm air and hot water units represent only about  1 percent of
the total residential heating  equipment installed in  1976 (Reference 4-40).
Coal for residential heating is either  stoker  or  hand fed. In the
commercial size sector, coal is more widely used  contributing nearly
12 percent of the total installed commercial steam and hot water capacity
(Reference 4-36).  Coal combusted in this  size category  is all stoker
fed.  Combustor designs allow the use of a variety of coals.   However,
bituminous and anthracite are  the primary  coal types burned.
       Equipment population statistics  for wood-fired heaters and
commercial boilers are not readily available.   Two recent EPA test
programs characterized emissions from wood-fired  stoves  and fireplaces.
In addition control variables  which affect these  emissions were  identified
and investigated to the extent that they could be varied (References 4-28

                                    4-12

-------
and 4-29).  The residential wood combustion source category will  be
reviewed separately in a subsequent effort of the NO   EA  program.
       With the increasing scarcity and escalating cost of clean  fuels,
coal is being reconsidered as contributing a larger share of the  fuel
supply for commercial as well as residential space heating.  Additionally,
existing advanced designs of residential coal-fired equipment allow for  a
relatively automatic combustion of coal.  However, the air pollution
impact of widespread coal-fired residential heating will  certainly be
significant.  Under adverse meteorological conditions, the air quality in
residential areas heated with coal is expected to degrade significantly  to
the point that National Ambient Air Quality Standards (NAAQS) could be
exceeded solely due to the residential equipment (Reference 4-41).
       The following subsections highlight some of the physical and
chemical characteristics of coal which affect emissions and equipment
operation.
4.2.3.1    Physical Properties
       Test results of two EPA-sponsored studies on coal  combustion in
residential size stokers indicate that physical properties of coals were
the main parameters affecting the composition and quantity of air
pollutants (References 4-25 and 4-26).  Stoker operation  and on-off
cycling did not prove as significant on air pollutant emissions as did the
varying physical properties of the coals tested.
       The free swelling index, volatile content, and coal size are the
primary coal properties that affect the emissions of particulates, smoke
and polynuclear organic material (POM).  The effect of coal ash content on
these emissions was found to be of secondary importance.
       The free swelling index is a measure of the caking property of
coals.  High volatile bituminuous coals have high free swelling index  and
thus, they tend to cake on stoker bed and form large clinkers. These
clinkers do not permit a uniform distribution of combustion air  which
leads to higher emissions of particulate (smoke), CO, hydrocarbons and POM.
       Figure 4-2 shows the effect of the free swelling index on
particulate emissions measured in two test programs on residential stoker-
fed heaters.  Anthracite and western subbituminous coals  with free
swelling indices less than 1 did not cake, permitting a more uniform air
                                    4-13

-------
       c
       o
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    8.0
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                                      35". to 40% COAL VOLATILE CONTENT
                                       22',, COAL VOLATILE CONTENT
WESTERN SUBBITIMINOUS COAL
WESTERN SUBBITIMINOUS COAL           (Ref.
BATTELLE STUDY, EASTERN BITUMINOUS COAL 4-25)
BATTELLE STUDY, WESTERN SUBBITUMINOUS COAL (Ref.
BATTELLE STUDY, ANTHRASITE (Ref.  4-22)    4'25)

I      I      I	I	I	1	
               0123456       78
                                Free swelling index of coal

       Figure 4-2.  Effect  of free swelling index  on  boiler particulate
                    emissions (Reference 4-26).
 distribution throughout  the bed.  Particulate emissions averaged 10  to  30
 percent of particulate emission levels from bituminous coals.
        The high volatile content of bituminous coal  also tended to produce
 high levels of particulate,  smoke, and POM emissions during tests on
 residential units.  POM  levels  were highest during  the "off" portion of
 the cycle when the low bed temperature and lack of  combustion air did not
 permit combustion of  tars  released from the coal  bed.  Figure 4-3 shows
 the effect of volatile content  on particulate emissions.  Anthracite,
 shown in Figure 4-2,  with  a volatile content of about 4 percent registered
 the lowest particulate emissions, 0.15 g/kg coal  (0.3 Ib/ton coal).  High
 volatile bituminous coals  emitted the highest particulate levels.  High
 particulate emissions were also accompanied by higher smoke and POM
 emissions.  Coal size and  ash content have a less pronounced effect  on
_particulate, smoke and POM emission from residential size heaters.
 However, a large amount  of fines in the coal tended  to increase
 particulate emissions during the "on" cycle.  This  was attributed to the
 combustion air carrying  the light particles to the  flue.
                                      4-14

-------
            8.0
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LJ
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        o
        CD
                    Free swelling
                    Index  5.7-1/2
                                                        Free swelling
                                                        Index = <1
            • WESTERN SUBBITUMINOUS COAL
            • WESTERN SUBBITUMINOUS COAL
            A BATTELLE STUDY, EASTERN BITTUMINOUS COAL
            V BATTELLE STUDY, WESTERN SUBBITUMINOUS COAL
          (Ref. 4-25)
          (Ref.4-25)
                H f-
                                I
I
                   20
                     25         30         35
                           VOLATILE CONTENT OF  COAL, %
                                                            40
                    45
      Figure 4-3.   Effect of coal volatile content  on boiler particulate
                     emissions (Reference 4-26).
        These emission  levels indicate that anthracite is the most
 desirable coal type for residential and small commercial heating
 equipment.  However,  availability of anthracite  is  limited, while
 bituminous coal  is  much more abundant and is indigenous  to many eastern
 states.  Western  subbituminous coals and processed  lignitic (smokeless)
 coals were investigated as alternatives to the combustion of bituminous
 coals in residential  furnaces and boilers.  As indicated in Figures 4-2
 and 4-3 these coals  have generally lower free swelling  indices but, except
 for the smokeless  coal, also have about the same amount  of volatile matter
 as bituminous coals.   Overall, subbituminous coals  were  found to be less
 polluting than bituminous coals and thus, in the absence of anthracite,
 are more desirable  as  fuels for residential and  commercial heating
 equipment (Reference 4-23).
4.2.3.2    Chemical  Properties
        Coal contains  a significant amount of elemental  metals of which a
-portion are released  to the atmosphere during combustion.  The rest is
 removed from the boiler with the bottom ash.  De Angel is and Reznik
 reported that in  general  less than 10 percent of trace  metal species in
                                      4-15

-------
the coal find their way to the atmosphere through the stack, however high
volatile mercury and selenium in the flue gas measured over 50 percent of
that introduced with the coal (Reference 4-25).  In another study,
Surprenant, et^ aj^, reported that at least 1 percent of the less volatile
trace metallic elements were released to the atmosphere from residential
units (Reference 4-42).  These trace elements generally include lead,
cadmium, arsenic, selenium and zinc, all of which are of significant
environmental concern.  Mercury, which is highly volatile, leaves the
boiler  in vapor form.
       Trace elements remaining in the bottom ash also constitute an
environmental concern.  Some of these elements, aluminum,  calcium, barium,
sodium, silicon and strontium, are leached by rainfall and can enter
potable water supplies.
       With wood combustion in residential stoves and fireplaces, high
resin content combined with high moisture content of unseasoned (green)
pine wood was attributed with high particulate, condensible organic and
polycyclic organic material (POM) emissions compared with  combustion of
drier and harder woods (Reference 4-28).  Resinous  material content and
chemical composition of soft woods,  such as pine, may then have a direct
impact on the organic emission characteristics from wood combustion in
residential systems.
4.3    PRODUCT CHARACTERIZATION
       The principal products of residential and commercial combustion
equipment are warm air, hot water or steam. Warm air furnaces  and hot
water boilers are generally smaller  than 0.1 MW (400,000 Btu/hr) heat
input capacity.  Steam units are a more popular equipment  category with
heat capacity above 0.4 MW (1.5 x 106 Btu/hr).  For warm air
applications, hot water or steam can be used as an  intermediate fluid to
exchange heat with a forced air circulating system.  Steam from small
commercial size units is also used in industrial process plants.
       As discussed in Section 3, direct warm air systems  exhaust the flue
gas directly into the heated air for maximum thermal efficiency.  Direct
heating, however, has the disadvantages of creating increased  ambient
levels of NOX, CO and HC in the space being heated.  These indoor areas
require good ventilation which then  reduces the effectiveness  of the
direct heating system.

                                    4-16

-------
4.4    N0¥ FORMATION
         /\
       Two mechanisms have been identified as responsible for NO
formation during the combustion process:  thermal NO  formation and fuel
                                                    J\
NO  formation.  The following subsections surrmarize these formation
  /\
concepts.  A more extensive discussion is given in Reference 4-43.
4.4.1  Thermal NO  Formation
       Thermal NO  results from the thermal fixation of molecular
                 ^
nitrogen and oxygen in the combustion air.  The detailed chemical
mechanism by which molecular nitrogen in the combustion air is converted
to nitric oxide is not fully understood.  In practical combustion
equipment, particularly for liquid or solid fuels, the kinetics of the
N2~^2 system are coupled to the kinetics of hydrocarbon oxidation and
both are influenced, if not dominated, by effects of turbulent mixing in
the flame zone.  It is, however, generally accepted that thermal NO
                                                                   /\
forms at high temperatures in an excess of 0^.  For natural gas and
light distillate oil firing, nearly all NO  emissions result from
                                          n
thermal fixation.  With residual oil and coal the contribution from fuel-
bound nitrogen can be significant and may even predominate.
4-4.2  Fuel NO  Formation
              ~~~/\
       Fuel NO  derives from the oxidation of the organically bound
              /\
nitrogen present in certain fuels such as residual and distillate oils.
Fuel NO  emissions are dependent on the nitrogen content of the fuel as
       /\
well as on combustion conditions.  Fuel NO  formation is strongly
                                          A
affected by the rate of mixing of the fuel and airstream in general, and
by local oxygen concentration in particular.
       Fortunately, with high nitrogen fuels only a portion of the fuel
bound nitrogen is converted to NO .  Barrett and Locklin investigated
                                 /\
the contribution of fuel N to total NO  emissions from oil-fired
                                      ^
commercial boilers (Reference 4-39).  Their results are summarized in
Figure 4-4.  As indicated, the contribution of thermal NO  to total
                                                         /\
NO  emissions is approximately 100 ppm.  Total NO  emissions steadily
  X                                              *
increase as the nitrogen content of the fuel increases.  However, the
fractional conversion of fuel nitrogen decreases as the fuel nitrogen
content increases.  Commonly reported conversion rates range from 40 to
60 percent for residual oils and to nearly 100 percent for distillate oils
(very low nitrogen content).

                                    4-17

-------
                      450
                     400
                      350
                   1
                   |300
                      250
                   I 200
                   o
                    a 150
                    in"
                    ,|
                    8 too
                    E
                    ui
                    0X  50
                           Symbols denote different
                           boilers
                                             N
                                               0.6
                              l      I     I      I
                             O.I    02   0.3    04
                              Nitrogen in Fuel.percent
0.5
  Figure 4-4.  Contribution of nitrogen in fuel oil to total  NOX  emissions
               from commercial boilers (Reference 4-39).

        Fuel nitrogen conversion to NO  when burning coal can range from
                                      A
 20 to 60 percent depending on the coal type and percent nitrogen  in the
 fuel (Reference 4-44).   In addition, this conversion is highly dependent
 on the fuel-air ratio.   Since coal in commercial and residential  equipment
 is generally burned in  stokers with high excess air levels,  conversion  of
 fuel nitrogen to NO  is high.
 4.5    EMISSION CHARACTERIZATION
        Emissions from natural gas-fired residential and commercial
 combustion sources include primarily NO. CO and HC.  When fuel oil  or
                                        A
-coal is burned,  smoke,  particulate and S0x are also emitted.  The levels
 of NOX,  CO and  HC from  oil and coal combustion are usually higher than
'those from gas  combustion.  Figures 4-5 and 4-6 illustrate general  trends
 of steady-state  smoke and  gaseous emissions from oil-fired residential
 heaters  and commercial  boilers,  respectively, as they are influenced by
                                     4-18

-------
             2.00
             1.50
           . 1.00
           i
             0.50
             0.00
                               Optimum settlna for minimum |
                               emissions and maximum
                               efficiency
                -20
                         20   40   60   80   100  120   140
                               Excess air, %
                  16  11  12
                             10
                                                             C02, *
  Figure 4-5.  General trend  of  smoke, gaseous emissions,  and efficiency
                versus stoichiometric ratio  for a residential  oil burner
                (Reference 4-7).

                                                     14
Figure  4-6.
           •        10       12
             Ptrctnt C0t in Flut Got
Gaseous  emissions characteristic  for a typical  commercial
boiler as influenced by combustion air setting
(Reference 4-45).
                                    4-19

-------
 combustion air settings.  For both equipment types the operating setting
 corresponding  to  lowest emissions of CO, HC, and smoke coincides with high
 NO   levels.  As the excess air is reduced from the theoretical setting,
   A
 concentrations of CO, HC and smoke increase because of lack of oxygen in
 the  flame and reduced turbulent mixing which leads to incomplete
 combustion.  At very high excess air levels, these emissions can also
 increase due to the excessive combustion air which cools the flame also
 resulting in incomplete combustion.
       One of the major factors contributing to high combustible
 emissions, particularly in domestic burners, is the transient operating
 mode.  The on-off cycle is a dominant characteristic of warm air furnaces,
 and  its  importance as a cause of increased emissions has been well
 documented (References 4-6 and 4-7).  A typical furnace cycle is shown in
 Figure 4-7.  The  burner is ignited at a point off the chart and, after a
 minute or so,  the blower starts circulating air over the heat exchanger.
 Four minutes later the burner flame is extinguished, and about 5 minutes
 after that the blower stops.  Investigations on a model residential
 heating  system indicated that the sizeable peak emissions measured during
 ignition and shutdown can account for most of the total combustible
 emissions.  Figure 4-8 shows qualitative emission traces from an oil
 burner during  a typical cycle.  CO and HC emissions peak at ignition and
 shutoff.  HC concentration drops to insignificant levels between the
 peaks, while CO emissions tend to flatten out at a measurable level.
 Parti cul ate emissions continuously taper off after the ign it ion-induced
 peak, whereas NO  emissions first rise rapidly for a short period and then
 continue to rise  at a more moderate rate as the combustion chamber
 temperature increases.  The operating time of most domestic burners
 seemingly is not  long enough for NO to reach equilibrium levels.
       The transient emissions are caused mainly by variations in the
 combustion chamber temperature.  At ignition, a cold refractory will not
 assist complete combustion and, therefore, peaks of CO, HC, and smoke can
-occur.   In addition to the cold refractory, wear and tear of the oil pump
 can  cause poor shut-off performance, hence high smoke and combustible
 emissions.  This  problem can be minimized by the use of solenoid valves in
 the  fuel tube  (delayed on-instant off), the placement of this valve nearer
 to the burner tip, and the use of smaller diameter tubes.

                                    4-20

-------
                       Fire
                       stops
                                             Area represents
                                             unused heat
                                                    Extrapolated
                                                    to zero
                                                    temperature
                                                    rise
                     Blower time in minutes
Figure 4-7.
Temperature rise across an oil-fired warm air furnace
heat exchanger during a typical cycle.
                               4-21

-------
 Filterable
Participate
                             NO
                                                 Burner
                                                   On
                                                   I          I
                                               Burner
                                                ,0ff
                    Time
                                         Time
       HC
             Burner
              On
I            1
             Burner
              Off
                                           CO
Burner
 Off
                    Tine *
                                                       Time -
       Figure 4-8.
       Characteristic  emissions  of oil burners during
       one  complete  cycle (Reference 4-7).
                                      4-22

-------
        In  general,  with  the  exception  of SO  emissions which depend
                                           /\
 entirely  on the  sulfur content  of  the  fuel, all other criteria pollutants
 are  primarily  a  function of  burner nozzle type, combustion chamber shape
 and  material,  and operating  practice.  The following subsections highlight
 some of these  parameters and how each  affects  the various criteria
 pollutant  emissions.
 4.5.1   Nitric  Oxide Emissions
        Nitric  oxide production  from fuel oil combustion  is highest in high
 temperature turbulent diffusion flames rich in excess oxygen.  NO
                                                                 A
 emissions  from residential heaters, which burn primarily natural gas and
 distillate oil that is relatively  low  in fuel  nitrogen content, are due to
 thermal NO .   The oxidation  of  molecular nitrogen in the combustion air
 depends on residence time and temperature.  The higher temperatures and
 long residence times promote production of thermal NO.  Fuel/air ratios
 have less effect on thermal  NO  production than on fuel nitrogen
 conversion, which is highly  affected by excess oxygen availability during
 pyrolysis of fuel nitrogen compounds.
 4.5.2  Carbon  Monoxide and Hydrocarbon Emissions
        Both CO and HC are products of  incomplete combustion.  Steady-state
 and  cyclic combustible emissions in small residential and commercial
 sources have been attributed to excessive firing rate (or input rate) and
 lack of scheduled maintenance.  A  field survey concluded that a large
 majority  of oil-fired residential  heating systems have an excessive firing
 rate which leads to high stack  losses  and reduced seasonal efficiency
 (Reference 4-46).  Oversized residential heaters cycle more frequently
 because the heating load is  met quickly and the furnace  shuts down.
 During the ignition and  shutdown periods, emissions of CO and HC are high
 because of flame quenching from the cold wall.  A reduction in burner
 capacity  (i.e.,  lower firing rate) reduces these emissions significantly
 and  increases  the overall  cycle efficiency of  the units.  Residential
 burner performance can usually  degrade with time; if so, the furnace emits
-umeccessarily high levels of combustible CO and HC.  Improper burner
 adjustment may cause flame impingement or reduced stoichiometry which lead
 to  incomplete  combustion.  Scheduled burner maintenance by skilled
 servicemen remedies this problem.
                                     4-23

-------
 4.5.3  Smoke and Particulate Emissions
       Smoke and particulates from oil-fired residential and commercial
 units consist primarily of carbon participate (soot) which is a product of
 incomplete  combustion.  These emissions increase with short furnace
 residence time and cold wall furnace effect.  Short furnace residence time
 is characteristic of small size combustion chambers of conventional
 residential heaters.  Larger fireboxes can help reduce particulate
 emissions by as much as one-fourth (Reference 4-7).  Combustion chambers
 of domestic oil burners are usually made of hard refractory, ceramic felt
 material or steel.  The temperature of a refractory lined chamber reaches
 steady state with combustion gases faster and retain the heat longer than
 steel chambers.  Therefore, residential oil burners with ceramic lined
 chambers emit lower particulate and smoke than do steel  chambers.  During
 the time in which chamber temperature is low, however, excess air levels
 must be increased to counteract the poor combustion due to low
 temperature.  Since it has not been practical to allow for altering the
 amount of excess air during a heating cycle, the initial high air level  is
 maintained  throughout, resulting in low thermal efficiency.
 4.5.4  Emission Factors and Emission Inventory
       Emission factors together with fuel consumption were used to
 calculate total 1977 emissions from combustion sources having heat input
 capacity less than 2.9 MW (10 x 106 Btu/hr) (Reference 4-47).   As
 discussed earlier, this site category also includes a significant number
 of boiler equipment used in industry in addition to those used for
 residential and commercial heating.  Fuel consumption and emissions in
 Table 4-3 are presented by end use.  As indicated, fuel  consumption data
 for residential systems were obtained directly from the Department of
 Energy (Reference 4-48).  Fuel consumption for the industrial and
 commercial  sources with heat input capacity less than 2.9 MW (10 x 106
 Btu/hr) was calculated using equipment installed capacity and load factors
 estimated in a recent EPA-sponsored study (Reference 4-36).
       Gas- and distillate oil-fired residential systems contributed the
 most to total NO  emissions from these sources.  This is due to the fuel
                A
'consumption for residential heating which accounted for nearly 65 percent
 of the total fuel consumption.
                                    4-24

-------
                          TABLE  4-3.   ESTIMATED 1977 AIR  POLLUTANT  EMISSIONS  FROM  STATIONARY

                                        FUEL  COMBUSTION SOURCES  WITH  HEAT  CAPACITY LESS  THAN

                                        2.9  MW  (10 x  106 8tu/hr)a
Sector
Residential0
Residential
and Commercial
Equipment
Harm air central
furnaces
Harm air space
heaters
Miscellaneous
combustion
Steam and hot
water heaters
Fuel
Natural gas
Distillate
oil
Natural gas
Distillate
oil
Natural gas
Distillate
oil
Natural gas
Distillate
oil
Residual oil
Coal
Total Capacity
MW (106 Btu/hr)
--
-
--
--
--
-
--
-
-
--
Fuelb
Consumption
EJ (Quads)
1.876C
(1.979)
1.354C
(1.428)
0.57C
(0.60)
0.42C
(0.44)
1.524C
(1.608)
0.926C
(0.977)
2. 1C
(2.2)
1.4C
(1.5)
0.11C
(0.12)
0.043C
(0.045)
Air Pollutant Emissions Gg (103 tons)
NO,
65.7
(??. 5)
33.8
(37.3)
19.9
(21.9)
10.5
(H-6)
53.3
(58.8)
27.4
(30.2)
82.8
(91.3)
77.9
(85. 9)
17.5
(19.3)
7.1
(7.8)
CO
19.0
(20.9)
33.8
(37.3)
5.7
(6.3)
10.5
(11.6)
15.2
(16.8)
27.4
(30.2)
17.8
(19.6)
41.7
(46.0)
1.64
(1.81)
7.53
(8.30)
HC
6.40
(7.10)
6.40
(7.06)
1.94
(2.14)
1.97
(2.17)
5.20
(5.73)
5.15
(5.68)
4.76
(5.25)
13.4
(14.8)
2.74
(3.02)
2.12
(2.34)
Particulates
7.50
(8.27)
10.3
(H-4)
2.30
(2.54)
3.20
(3.53)
6.10
(6.73)
8.33
(9.19)
16.6
(18.3)
10.6
(11.7)
9.09
(10.0)
150.2
(165.6)
so,
0.49
(0.54)
146
(161)
0.15
(0.17)
45.4
(50.1)
0.40
(0.44)
118.4
(130.6)
0.62
0.68
150.2
(165.6)
52.6
(58.0)
30.7
(33.8)
ro
en
            "Based on data from References 4-36, 4-47, and 4-48.

            bEJ * 1018 Joules = 0.948 Quads * 0.948 x 10lb Btu
            cFuel consumption for residential units was obtained from Department of Energy (Reference 4-48).

-------
                                                TABLE 4-3.   (Concluded)
Sector
Commercial
and Industrial
TOTAL
Equipment
Cast Iron
boilers
Hatertube
boilers
Flretube
boilers

All equipment
Fuel
Natural gas
Distillate
oil
Residual oil
CM!
Natural gas
Distillate
oil
Residual oil
Coal
Natural gas
Distillate
oil
Residual
oil
Coal
All fuels
Total Capacity
»l (106 Btu/hr)
143,520
(489,495)
33,730
(115.041)
53,790
(183,456)
31,590
(107,742)
5,770
(19,679)
4.490
(15,313)
5,240
(17,872)
1,900
(6,480)
79,090
(269,748)
31,530
(107,538)
48.200
(164,393)
14,420
(49.181)
--
Fuelb
Consumption
EJ (Quads)
1.8
(1.9)
0.35
(0.37)
0.47
(0.50)
0.097
(1.0)
0.053
(0.056)
0.021
(0.023)
0.015
(0.016)
0.012
(0.013)
1.358
(1.433)
0.37
(0.39)
0.354
(0.374)
0.11
(0.116)
15.22
(16.97)
Air Pollutant Emissions Gg (103 tons)
NO,
91.7
(101.1)
23.7
(26.1)
84.6
(93.3)
14.6
(16.1)
3.16
(3.5)
1.18
(1.3)
2.38
(2.6)
3.0
(3.3)
31.0
(34.2)
12.8
(14.1)
30.7
(33.9)
14.1
(15.6)
708.8
(781.6)
CO
35.3
(38.9)
0.56
(0.61)
0.66
(0.73)
21.3
(23.5)
1.06
(1.17)
0.06
(0.07)
0.02
(0.02)
0.91
(1.00)
15.2
(16.8)
0.34
(0.38)
0.29
(0.32)
5.40
(5.95)
261.4
(288.3)
HC
4.06
(4.18)
3.34
(3.68)
11.8
(13.8)
5.53
(6.10)
0.18
(0.20)
0.01
(0.01)
0.07
(0.08)
0.19
(0.21)
1.75
(1.93)
2.05
(2.26)
5.12
(5.65)
3.40
(3.75)
87.6
(96.6)
Partlculates
6.88
(7.59)
4.18
(4.61)
13.2
(14.6)
314.3
(346.6)
0.05
(0.05) -
0.18
(0.20)
0.42
(0.46)
23.5
(25.9)
3.02
(3.33)
2.57
(2.83)
5.73
(6.32)
130.0
(143.4)
728.3
(803.1)
SOX
0.53
(0.58)
37.6
(41.5)
225.6
(248.8)
110.6
(122.0)
0.02
(0.02)
3.27
(3.61)
6.70
(7.39)
16.0
(17.6)
0.23
(0.25)
18.7
(20.6)
92.1
(101.61)
91.8
(101.2)
1,148.1
(l,26fi.O)
ro

-------
                          REFERENCES FOR SECTION 4
4-1.   Levy, A., et al., "A Field Investigation of Emissions From Fuel  Oil
       Combustion For Space Heating," American Petroleum Institute
       Publication 4099, November 1971.

4-2.   Thrasher, W. H., and D. W. De Werth,  "Evaluation of the Pollutant
       Emissions From Gas-Fired Forced Air Furnaces,"  American Gas
       Association Research Report No. 1503, May 1975.

4-3.   Brookman, G. T., and Kalika, P. W., "Measuring  The Environmental
       Impact of Domestic Gas-Fired Heating Systems,"  presented at the
       67th Annual Meeting of the Air Pollution Control Associati
       (APCA), Denver, Colorado, June 1974.

4-4.   "NOX Emissions of Seven Furnaces Predominant in the California
       Area," Report by the American Gas Association Laboratories (AGAL)
       to the Gas Appliance Manufacturers Association  (GAMA) in response
       to the California imposed Model Rule, August 1978.

4-5.   De Werth, D. W., and R. L. Himmel, "An Investigation of Emissions
       From Domestic Natural Gas-Fired Appliances," presented at the 67th
       Annual Meeting of the Air Pollution Control Association (APCA),
       Denver, Colorado, June 1974.

4-6.   Barrett  R. E., et al., "Field Investigation of Emissions From
       Combustion Equipment For Space Heating," EPA-R2-73-084a (API
       Publication 4180), NTIS-PB 223 148, June 1973.

4-7.   Hall, R. E., et al., "A Study of Air Pollutant  Emissions From
       Residential Heating" Systems," EPA-650/2-74-003, NTIS-PB 229 697,
       January 1974.

4-8.   Hollowell, C. D., et al., "Combustion-Generated Indoor Air
       Pollution I.  FielTMeasurements 8/75 - 10/75," LBL-4416, UC-11,
       TID-4500-R63, January 1976.

4-9.   Cote, W. A., et al., "A Study of Indoor Air Quality,"
       EPA-650/4-74-M2, NTIS-PB 238 556,  September 1974.

4-10.  Surprenant, N. F., et al., "Emission Assessment of Conventional
       Stationary Combustion Systems: Volume 1.  Gas-  and Oil-Fired
       Residential Heating Sources," EPA-600/7-79-029b, NTIS-PB 298-494,
       May 1979.

4-11.  Personal communication with Don Price, TRW Inc., Redondo Beach,  CA,
       August 16, 1979.
                                      4-27

-------
4-12.  Hama, G. M., "Report of Test For Carbon Monoxide and Other
       Contaminants on a Maxon Premix Series RG-IV Airflow Burner,"
       Certification Tests by the American Board of Industrial Hygiene,
       Akron, OH, January 1969.

4-13.  Howekamp, D. P., "Flame Retention — Effects on Air Pollution,"
       U.S. Department of Health, Education and Welfare, presented at the
       Ninth Annual Convention of National Oil Fuel Institute, Atlantic
       City, New Jersey, June 1970.

4-14.  Singh, J. J., ert a/L_, "An Investigation of Size-Dependent
       Concentration of Trace Elements in Aerosols Emitted From the
       Oil-Fired Heating Plants," NASA Technical Memorandum TMX-3401,
       Norfolk, VA, July 1976.

4-15.  Whaley, H., et a!., "Energy Conservation and Emissions From Two
       Residential "Furnaces Using an Emulsified Water-in-Oil Fuel,"
       Presented at the 71st Annual Meeting of the Air Pollution Control
       Association (APCA), Houston, Texas, June 1978.

4-16.  Combs, L. P- and A. S. Okuda, "Commercial Feasibility of an Optimum
       Residential Oil Burner Head," EPA-600/2-76-256, NTIS-PB 259 912,
       September 1976.

4-17.  Combs, L. P. and A. S. Okuda, "Residential Oil Furnace System
       Optimization Phase  II," EPA-600/2-77-028, NTIS-PB 264 202,
       January  1977.

4-18.  Okuda,  A. S. and L. P.  Combs, "Field Verification of Low-Emission
       Integrated  Residential  Furnaces,"  in the Proceedings of the Third
       Stationary  Source Combustion Symposium, EPA-600/7-79-050a,
       NTIS-PB  292 539, February 1979.

4-19.  Okuda,  A. S. and L. P.  Combs, "Design  Optimization  and Field
       Verification of  an  Integrated Residential Furnace Phase 1,"
       EPA-600/7-79-037a,  NTIS-PB  294  293, February  1979.

4-20.  Higginbotham,  E. B.,  "Combustion Modification  Controls for
       Residential and  Commercial  Heating Systems:  Volume II.  Oil-fired
       Residential Furnace Field Test," EPA-600/7-81-123b,  July  1981.

4-21.  Hall,  R.  E., "The Effect  of  Water/Distillate Oil Emulsions  on
       Pollutants  and Efficiency of Residential and Commercial Heating
       Systems," Presented at  the  68th  Annual Meeting of the  Air  Pollution
       Control  Association,  Boston, MA, June  1975.

4-22.  Hall,  R.  E., "The Effect  of Water/Residual  Oil Emulsion on  Air
       Pollutant Emissions and Efficiency of  Commercial Boilers,"  ASME
       Publication 75-WA/APC-l,  July  1975.
                                     4-28

-------
4-23.  Beard, J. T. and Robert E. Hall,  "Performance and  Air  Pollutant
       Emissions of an Experimental Water/Residual  Oil  Emulsion  Burner  in
       a Commercial Boiler," EPA Draft Report,  Research Triangle Park,
       North Carolina, September 1979.

4-24.  Personal Conmunication with Robert E.  Hall,  U.S. EPA,  Research
       Triangle Park, North Carolina, May 27, 1980.

4-25.  Giammar, R. D., et al_., "Emissions From  Residential  and  Small
       Commercial Stoker-Coal-Fired Boilers Under Smokeless Operation,"
       EPA-600/7-76-029, NTIS-PB 263 891, October 1976.

4-26.  De Angelis, D. G. and R. B. Reznik,  "Source Assessment:   Coal-Fired
       Residential Combustion Equipment  Field Tests, June 1977,"
       EPA-600/2-78-004o, NTIS-PB 283 699,  June 1978.

4-27.  Engdahl, R. B., "Cross-Feed Combustion For Clean Burning  of  Solid
       Fuels For Residences," Presented  at  the  71st Annual  Meeting  of the
       Air Pollution Control Association (APCA), Houston, Texas, June 1978.

4-28.  De Angelis, D. G., et al_., "Preliminary  Characterization  of
       Emissions from Wood-Fired Residential  Combustion Equipment,"
       EPA-600/7-80-040, NTIS-PB 80-182066, March 1980.

4-29.  Personal comnunication with Robert Hall, U.S. EPA, Research
       Triangle Park, NC, November 25, 1980.

4-30.  Locklin, D. W. and R. E. Barrett, "Guidelines for  Burner
       Adjustments of Commercial Oil-Fired  Boilers," EPA-600/2-76-088,
       NTIS-PB 251 911, March 1976.

4-31.  "Specifications for Fuel Oils," ASTM D-396-75, ASTM  Standards for
       Petroleum Products (Part 17), American Society for Testing and
       Materials, Philadelphia, PA, 1975.

4-32.  Siegmund, C. W., "Low-Sulfur Fuels are Pifferent," Hydrocarbon
       Processing. Vol. 49, No. 2, pp. 89-95, February  19775".

4-33.  Shelton, E. M., "Burner Fuel Oils,"  Bartlesville Energy Research
       Center, BERC/PPS-75/2, Bartlesville, OK, August  1975.

4-34.  Schmidt, P. F., "Knowing How Oil  Behavior Makes  For  Better
       Operation," Power, Vol. 118, No.  10, p.  28,  October 1975.

4-35.  Offen, G. R., et al^, "Control of Particulate Matter From Oil
       Burners and Boilers," EPA-450/3-76-005,  NTIS-PB  285 495,  April 1976.

4-36.  Devitt, T., et aj^, "The Population  and  Characterization  of
       Industrial/Conroercial Boilers," EPA  600/7-79-178a,
       NTIS-PB/80-150881, August 1979.
                                    4-29

-------
4-37.  Martin, G. B., "Evaluation of NOX Emission Characteristics of
       Alcohol Fuels in Stationary Combustion Systems,"  Presented at the
       Joint Meeting, Western and Central States Sections,  The Combustion
       Institute, San Antonio, Texas, April  1975.

4-38.  Martin, 6. B., "Environmental Considerations in the Use of
       Alternate Clean Fuels in Stationary Combustion Processes," in
       Symposium Proceedings:  Environmental  Aspects of  Fuel  Conversion
       Technology (May 1974, St. Louis,  MI),  EPA-650/2-74-118.
       NTIS-PB 233 304/AB, October 1974.

4-39.  Barrett, R. E., and D. W. Locklin, "Field Investigation of
       Emissions From Commercial Boilers," Presented at  the 69th  Annual
       Meeting of the Air Pollution Control Association  (APCA), Portland,
       Oregon, June 1976.

4-40.  "General Housing Characteristics  for the United States and Regions;
       1976," U.S. Department of Commerce, Bureau of Census,  Current
       Housing Reports, Series H-150-76. Part A, U.S. G.P.O.,
       Washington, DC, 1978.

4-41.  Weber, R. C., "Impact on Local Air Quality From Coal-Fired
       Residential Furnaces," Presented  at the 71st Annual  Meeting  of the
       Air Pollution Control Association, Houston,  Texas,  June 1978.

4-42.  Surprenant, N., et aJL, "Final Report, Volume II:   Preliminary
       Emissions Assessment of Conventional Stationary Combustion
       Systems," EPA Contract 68-02-1316, Task Order II, GCA  Corp.,
       Bedford, MASS, March 1976.

4-43.  Mason, H. B., et al., "Preliminary Environmental  Assessment  of
       Combustion Modification Techniques. Volume  II, Technical  Results,"
       EPA-600/7-77-119b, NTIS-PB 276/AS, October 1977.

4-44.  "Air Quality and Stationary Source Emission  Control,"  U.S. Senate,
       Committee on Public Works, Serial No.  94-4,  March 1975.

4-45.  Locklin, D. W. and R. E. Barrett, "Guidelines for Burner
       Adjustments of Conrnercial Oil-Fired Boilers," EPA-600/2-76-088,
       NTIS-PB 251 911, March 1976.

4-46.  Bonne, U., et al_., "Effect of Reducing Excess Firing Rate  on  the
       Seasonal Efficiency of 26 Boston  Oil-Fired Heating  Systems,"
       Presented at Conference on Efficiency  of HVAC Equipment and
       Component II, Purdue University,  Indiana, April 1975.

4-47.  Waterland, L. R., et al., "Environmental Assessment of Stationary
       Source NOX ControlTecFnologies -- Final Report," Acurex Draft
       Final  Report FR-80-57/EE, EPA Contract No. 68-02-2160, Acurex
       Corp., Mountain View, CA,.April 1980.

4-48.  Personal conmunication with Charles Allen of the  Department  of
       Energy, Washington, DC, on preliminary data  from  EIA Annual  Report
       to Congress,  May 1, 1979.
                                    4-30

-------
                                 SECTION 5
                     PERFORMANCE AID COST OF CONTROLS

       This section discusses the performance and cost of various control
options applicable to gas-, oil-, and coal-fired residential systems.
Controls for each of these equipment categories are discussed in three
separate sections according to the fuel burned.  Control technology
developed specifically for NO  emission reduction are also highlighted
                             ^
and discussed separately from controls specifically developed for other
pollutants.  Published costs and energy considerations of these controls
are also summarized for each fuel category.  All costs are in 1978 dollars
unless otherwise indicated.  Discussion of emission control technology for
commercial steam and hot water boilers is limited because of lack of
investigative efforts in this area.  However, technology transfer from the
small industrial boiler sector is discussed.
5.1    EMISSION CONTROL ALTERNATIVES FOR GAS-FIRED RESIDENTIAL SYSTEMS
       NO  emission control techniques for gas-fired residential furnaces
         /\
have been investigated since the early 1970's by the American Gas
Association Laboratories (AGAL), the Gas Appliance Manufacturers Association
(GAMA), and the EPA.  Early work by AGAL quantified the variation of NO ,
                                                                       ^
CO, and hydrocarbon emissions from gas-fired residential units according to
burner type and firebox design.  This work showed that multiport gas burners
were found to emit approximately 25 percent higher NO  than single port
                                                     rt
burners (Reference .5-1).  This was attributed to a compact, intense flame
front with the multiport burners which promotes NO  formation.  Single
                                                  n
port burners have larger burner flame volumes which result in fewer high
intensity temperature regions to promote NO  formation (Reference 5-2).
                                           A
Some observations were also made by AGAL on the effect of primary air
setting (primary aeration) and heat exchanger material on NO  emissions.
                                                            ^
These effects were generally found to be less important than burner design
(Reference 5-1).

                                    5-1

-------
5.1.1  Nitric Oxide Control
       Because NO  emissions from combustion of natural gas are from
                 A
thermal NO formation, control techniques are aimed at controlling flame
temperature, residence time, and oxygen availability at the high temperature
flame region.  Five major NO  control options have been identified for
                            ^
residential gas-fired warm air furnaces and hydronic boilers.  These control
options are:
       t   Radiant screens
       t   Secondary air baffles
       •   Modulating combustion cycle
       t   Heat transfer module (HTM)
       •   Surface combustion burner (Bratko type)
       •   Catalytic combustors
       The following subsections discuss the NO  reduction performance,
                                               n
applicability and cost of each of these control options.
5.1.1.1    Radiant Screens
       Himmel and De Werth of AGA originally reported that infrared gas
burners emit lower nitric oxides than conventional type burners (Reference 5-2),
Incandescent radiant screens in a natural gas flame tend  to approach the
level of infrared burners by radiating heat to the surroundings and
cooling the flame.  An inverted "V" screen was placed above the tubular
multiport burner and extended the length of the burner.  For a single port
upshot burner, a circular screen was placed around the burner.  Both
arrangements are illustrated schematically in Figure 5-1.
       Table 5-1 summarizes the performance of radiant screens on three
warm air furnaces.  As shown, the NO  was reduced from 36  to 76 percent
                                    rt
with an average reduction of 58 percent.  The radiant screen performance
was more significant with tubular multiport burners.   Similar results were
obtained in other warm air furnaces when burners were modified by
installation of radiant screens.  In general, this control technique was
also found to increase steady-state furnace efficiency slightly due to
increased flame and burner radiation.
       AGAL, however, warns that the radiant screen concept, although
workable, needs further investigation to assess its durability in the
flame,  its potential deterioration or deformation and overall safety.
Some concerns were also published in a recent GAMA report  in response to

                                    5-2

-------
                       Inverted "v"
                       screen (extends the
                       length of the burner)
                 Cross-sectional
                 view of tubular
                 burner
                                                                Flame
                                                                diverter
                                                       Burner
               (a)
    For multiport tubular burner
          (b)

For single port upshot burner
Figure  5-1.  General arrangements of  screens for  gas-fired  residential
              burners (based on illustrations from Reference 5-1).
TABLE  5-1.  EFFECT ON CO AND NOX EMISSION OF PLACING RADIANT  SCREEN
             IN  BURNER FLAME  (Reference 5-1)
Unit Sample C02
Percent
FAF 23 — Tubul
No Screen
Screen
FAF 25 -- Tubul
No Screen
Screen
FAF 9 — Single
No Screen
Screen
ar Multiport
8.50
8.30
ar Multiport
7.70
7.75
Port Upshot
4.05
4.05
Flue Gas Concentration
ppm, (0% 02)
CO NO N02 NOX

14
15

8
11
with
15
44

104.9
23.4

76.7
21.5

0
1.6

3.7
3.4

104.9
25.0

80.5
24.9
NOX
Percent
Change


-76%


-69%
Flame Spreader
61.3
37.3
1.6
3.0
62.9
40.3

-36%
  FAF  =  Forced Air  Furnace
                                    5-3

-------
the recommendations by the California Air Resources Board  (CARB)  for the
potential commercial application of radiant screens to  control  NOX from
warm air furnaces (References 5-3 and 5-4).  Some of  the potential
problems presented by GAMA included sensitivity  of performance to screen
location, effect on CO emissions, and deterioration.
       The screen design and location in or around the  burner are critical
to its performance.  Figure 5-2 illustrates how  NOX reductions can
drastically vary with location of the screen.  This sensitivity precludes
retrofit application to existing units unless they are  made by skilled
service  appliance personnel.  GAMA also  indicated that  CO  emissions can
increase significantly with the application of screens,  even with furnace
manufacturer-suggested air settings.  Furthermore, if these air settings
were to  become misadjusted during installation or servicing, unacceptable
CO emissions would result.  Test results by GAMA summarized in Table 5-2
show that CO increased above 1000 ppm with natural gas  and a liquified
natural  gas.  With regard to screen durability  it is  expected that the
cycling  operation of the residential equipment would  impose numerous
thermal  shocks to the screens which could  eventually  deform or break.
Screen  deterioration could  lead to loss  in performance and/or excessive CO
and HC  emissions.
                    60
                     55
                   I 5°
                   £ 40
                     35
                        No Screen
                             2.5
                                    5.0
                                           7.5
                                                   10.0 on
                             1.0     2.0      3.0

                       Portion of screen tbove Meker Burner Port
                                                   4.0 In.
   Figure  5-2.
Effect on NOX emissions of placing a screen  in  the flame
of a Meker Type burner (Reference 5-3).
                                     5-4

-------
    TABLE 5-2.  EFFECT OF A RADIATING SCREEN FROM A FURNACE OPERATED ON
                CLEVELAND NATURAL AND ALGERIAN LNG (Reference 5-3)

Test Conditions
A -- Unmodified Burners
— Manufacturer's recommended setting
— "Hard" flame setting
~ "Soft" flame setting
B — Inverted "V" 10 x 10 mesh inconel
screen added to burners with manu-
facturers suggested air shutter
setting
C ~ Same as "B" except air shutters
wide open (hard flame)
D -- Same as "B" except air shutters
closed (soft flame)
Steady State Flue Gas
Concentration, ppm Air Free
Cleveland
Natural Gas
NOX

70
72
63


31
33
36
CO

10
109
693


30
1000+
1000+

Algerian Gas
NOX

65
—
--


28
28
32
CO

10
--
--


480
1000+
1000+
5.1.1.2    Secondary Air Baffles
       The effect of the secondary air baffle is to control secondary
airflow into the flame front.  Decreasing excess oxygen availability at
peak temperatures with reductions in secondary airflow was found to reduce
NO  emissions on the order of 10 to 40 percent (Reference 5-1).
However, NO  reductions without increases in CO emissions were generally
           /\
limited to about 15 percent.  The effect of the secondary air baffle was
found to be sensitive to its geometry and positioning with respect to the
burner port.  Therefore, concerns expressed by GAMA with this technique
are similar to those pointed out for the radiant screen control option.
                                    5-5

-------
Furthermore,  it is not clear whether the secondary air baffles can be
applied to all types of residential burner designs.
5.1.1.3    Modulating Furnace
       The modulating furnace also tested by AGAL is a commercially
available residential heater design.  The furnace differs from
conventional  units in that the firing rate is altered to respond to the
heating load  demand instead of cycling on and off.  In this manner, the
furnace is essentially derated, yielding a cooler flame which apparently
leads to lower NO  emissions.  The reported NO  emission factor for
                 x                           /-X
this furnace  design is 24.9 ng/J.(0.058 lb/10  Btu) (Reference 5-1).
This corresponds to about a 40 percent reduction from emission levels of
conventional  furnaces.
       GAMA indicated that this reduction in N0¥ mass emission achieved
                                               /\
with the modulating furnace was due to the single-port inshot burner type
used originally rather than the reduced heat input rate as indicated by
AGAL (Reference 5-3).  However, it can be speculated that elimination of
the on-off cycle should reduce combustible emissions because CO and UHC
emission peaks characteristic of ignition and shutdown would decrease.
However, no emission data are available to substantiate this hypothesis.
5.1.1.4    Heat Transfer Module (HTM)
       The HTM by Amana shown in Figure 5-3 has been commercially
available for about 6 years.  The design includes a perforated burner
located in the center.  The natural gas mixes with air through the many
holes of the  burner and burns at the burner surface.  The heat is
transferred to an intermediate glycol solution in small tubes imbedded in
a close fitted fin arrangement surrounding the burner.  The glycol then
transfers heat to room air.  The HTM is used for both heating and air
conditioning  and is designed for outdoor installations.  One additional
important feature of the HTM furnace is the lack of a pilot.  The flame is
spark ignited instead of using a pilot flame.  Thus seasonal fuel
consumption is reduced compared with pilot ignition furnaces.  NO
emissions reported by AGAL averaged 7.74 ng/J.(0.018 lb/106 Btu) which
corresponds to an emission reduction of about 80 percent from conventional
•warm air furnace design (Reference 5-1).
                                    5-6

-------
         The I Exclusive
  Here's  how  it works:
Gas (natural or propane) Is pulled front
the gas valve by the combustion blower
into the HTM* HearBsetia«gef-burner.
The burner Is only 4*  high x  2" 1n-
diameter,
A spark plug  ignites the gas ami air
mixture in the burner. No wasteful, both-
ersome pilot light. Wind does not affect
its operation,
•A flame probe monitors  the bower to
five proof of combustion, If combustion
doesn't'lake-pjaee, the ffam® probe wlH*
close the gas vaive within 15 seconds.
The stainless steel burner provides 9000
tiny fiames  which produce extremely
hot ffoe gases.
These 0830$ passing  through the por-
ous  matrix create high  turbulence to
produce rapid  heat transfer. Exclusive
porous matrix is made up of thousands
"Of copper coated  steel ball® fused to-
v..;:C3)
   gether to perform the function of heat
   exchange,
(§} The solution (50% water and 50% eth-
   ylene glycol to, prevent freezing) carry-
   ing tubes embedded in the matrix pick
   up the heat and transfer the hot solu-
   tion,  moving at 4,7  feet per second,
   through the HTM* Heat Exchanger.
(7) A limit control monitors the tempera-
   ture of the solution. And, if it rises above
   design temperatures, it shuts down the
   system.
($} You  get 7% -10%  more usable heat
   than  industry standards (depending on
   the firing rate) from the gas burned be-
   cause of less heat loss through the flue.
{9} The heater keeps the temperature of
   the HTM*  Heat Exchanger above sur-
   rounding temperature at  ail times, so it
   remains dry and untarnished by atmos-
   pheric moisture.
                  Figure 5-3.   Amana Heat  Transfer Module  (HTM)

                                             5-7

-------
       Recently, the HTM combustor has  been  tested  by  the Southern
California Gas Company.  Preliminary results indicate  that the Amana
design might not be capable of the 80 percent NO  reduction reported by
                                               A
AGAL.  Follow-up measurements are scheduled  for the near future to verify
the validity of this new finding (Reference  5-5).
5.1.1.5    Surface Combustion Burner
       A schematic of the surface combustion burner by Bratko is
illustrated in Figure 5-4.  This burner employs surface combustion of
premixed natural gas and air on a refractory porous material.  The burner
becomes incandescent and radiates heat  to  an air-cooled firebox.  In this
manner, the combustion zone is maintained  below about  1,250 K
(1,790°F).  NO  emissions of about 7 ng/J  (0.016 lb/106 Btu),
              A
corresponding to over 80 percent reduction,  have been  reported with a
prototype furnace using the surface combustor (Reference 5-6).  The
furnace maintains steady-state thermal  efficiencies of 80 percent or more
by operating with only 10 percent excess air.
                                            TOCONVECTIVE HEAT EXCHANGER
                       /VWWV
                        I   I!   !   !   I
                               COOLING AIR
        Figure 5-4.  Schematic of the  Bratko Burner  (Reference 5-6),
                                    5-9

-------
       The refractory surface combustion concept is not a new one.  In
fact, some commercial direct fired heaters use this refractory burner
(refer to Section 3.2.2 for discussion).  NO  emissions data from those
                                            ^
commercial units are, however, not available.
5.1.1.6    Pulse Combustors
       The concept of pulse combustion has been known since the turn of
the century.  This concept, illustrated in Figure 5-5, involves combustion
in a chamber fitted at one end with mechanical flapper valves and at the
other end with an open exhaust pipe.  The fuel (natural gas, propane or
light distillate) is introduced with the air through the flapper valves.
The mixture entering the chamber is ignited with an electric spark plug.
the resulting pressure of combustion closes the flapper valves and forces
the product gases through the exhaust pipe.  The exhaust products leaving
the chamber in time create a negative pressure, which causes the valves to
open, in a manner similar to an internal combustion engine,  thus repeating
the cycle.  The most extensive application of pulse combustion was in the
German VI "buzz bomb" during World War II.
       Application of the mechanical valved pulse combustor  for home
heating has been studied since the early 1950's.  The simplicity of
construction, compactness, and self-powered characteristic of this burner
are attractive advantages over conventional residential burners.  However,
although a hydronic system using pulse combustion was commerically offered
over two decades ago, there are no marketed systems in use today
(Reference 5-7).  AGAL is currently investigating pulse combustion for
residential heating using a condensing exhaust gas system.  Preliminary
N0x emissions from pulse combustion of Cleveland natural gas range
between 19 and 20 ng/J (0.044 and 0.047 lb/106 Btu) (Reference 5-8).
Commercialization of a pulse combustor residential heating system is
expected in 1981 (Reference 5-8).
5.1.1.7  Catalytic Combustors
       Catalytic residential combustors offer potential for  very low-NO
                                                                       ^
emissions while maintaining good combustion efficiency (Reference 5-7).
The catalytic agent, usually in the precious metal family, promotes
combustion of the fuel at low temperatures in the range of 755 to 1,366 K
(900 to 2,000°F.).  At these low temperatures, thermal NO  formation is
                                                        n
significantly reduced..  Large amounts of combustion air are, however,

                                    5-10

-------
AIR
     GAS
        AIR
                        SPARK  PLUG


                            COMBUSTION CHAMBER
                   y,  ,.    \
                   Hi!  :•:-:;    \

                   V.-'W' •'.":•.
                   .. v--
                                       TAILPIPE
                   •FLAPPER  VALVES


               A.  STARTING OPERATION
               B.  EXHAUST  PHASE  CINLET CLOSED)
       CAS
                                                         EXHAUST

                                                         PRODUCTS
                                                         AIR
               C.  INTAKE  PHASE  (INLET OPEN)
Figure  5-5.   Schematic  operating  cycle of a pulse  combustion device.



                                  5-11

-------
required with catalytic combustors.   The use of a condensing residential
system, in which the latent heat of  water vaporization is  recovered by
condensing the exhaust gas, is a viable option for minimizing heat losses
due to high excess air levels.  Catalytic combustors are  not commercially
available.  However, research groups and trade organizations are now
investigating its commercial feasibility for residential warm air and hot
water systems burning natural gas.   Performance and emission data for
these systems have not yet been published.
5.1.2  Carbon Monoxide and Unburned  Hydrocarbon Control
       Gas-fired heating appliances  and commercial boilers emit  some level
of CO and hydrocarbons during steady-state combustion. These levels are
generally low for well adjusted (tuned) gas burners.   AGA  Laboratories
reported an average CO emission level of about 8 ppm on an air-free basis
for forced air furnaces and 4 to 70  ppm for hot water and  steam  boilers
equipped with atmospheric gas burners.  Aliphatic aldehydes expressed as
formaldehyde (HCHO) generally averaged less than 1 ppm (Reference 5-1).
       The well adjusted or tuned condition of residential furnaces and
heaters equipped with atmospheric gas-fired burners can degrade  with
extended use in dirty environments.   The low CO blue flame, characteristic
of a tuned condition, will tend to  eventually change with  poor
housekeeping or long time between service.   The blue flame changes to a
yellow-tip flame which is indicative of high CO emissions.  AGA1  indicated
that yellow-tip gas flames, which occur during high input  rates  and low
primary air aeration, can be the cause of CO emissions of  200 ppm and
above (Reference 5-1).
       The only practical control option available to reduce CO  and other
combustible emissions from untuned  atmospheric gas burners is to provide  a
yearly service by skilled service personnel.  During regularly scheduled
service calls, the excess combustion air, which is the primary control
variable, can be set at a correct operating range.  Guidelines for
minimizing air pollution and maintaining high efficiency  for gas-fired
furnaces, developed by Battelle and  AGAL,. were recently published by EPA
(References 5-9 and 5-10),  Figure 5-6 illustrates that the normal excess
air level for well adjusted gas-fired heaters falls between 40 and
90 percent.  Excess air settings much above 40 percent will unnecessarily
reduce furnace efficiency due to more sensible heat being  carried to the

                                    5-12

-------
u
8
s
&
                                    Incr»o»ing Combustion  Air
 60    40    20   6

Air Deficiency, percent
                                                                120
                                    Excess Combustion Air, percent
                                 9.7    8.5/^,7.3/^6.5^  5.8

                                 *— CO,, percent (noturoi gos)
                                 10.7   9.8    8.5   7.6    6.7

                                «—   C02, percent (LP Gos)
     Figure  5-6.
             Effect  of air  adjustment on gaseous emissions for a

             typical atmospheric  gas burner (Reference 5-9).
                                        5-13

-------
stack.  Reduced furnace efficiency has an adverse effect on overall  mass
emissions because more fuel  is burned and thus more pollutants are
generated for a given amount of heat delivered .   Maximum furnace
efficiency for conventional  equipment is limited  to about 85 percent due
to high stack gas temperatures necessary to avoid flue gas condensation.
Typical factory adjusted residential furnaces have approximately 75  to
80 percent furnace efficiency at steady-state conditions.
       As indicated in Section 4, CO and HC emissions occurring during
furnace ignition and shutdown operation can account for most of these
emissions.  Therefore, one method of reducing CO  and HC is to reduce the
frequency of furnace cycling.  This can be accomplished by reducing  the
firing rate of gas burners.   Lower firing rates necessitate longer
furnace-on periods in order to deliver a given amount of heat.
Consequently, this reduces the number of on-off cycles over an entire
heating season.  Reduced firing rate (or "derating") also increases  the
residence time of combustion products in the firebox which tends to  reduce
steady- state combustible emissions.  Reduced firing rate for existing
furnaces can be accomplished by replacement of the existing burner orifice
with smaller capacity orifices.  Derating can accelerate furnace corrosion
due to increased condensation during cyclic operation.  This aspect  can
become a practical limitation to derating existing units.  For new units,
it is desirable to match closely the capacity of  the furnace to the  heat
load requirements of the residence.  Residential  heating systems in  the
past have generally been oversized.
5.1.3  Cost and Energy Impact of Controls
       Pending further verification of the performance of the Amana  HTM,
this burner design is presently considered the best available NO
                                                                /\
control technology for gas-fired residential and  commercial heaters.  The
low-NOx emission concept of the HTM design can be utilized for other
furnace types according to Amana (Reference 5-4).  An estimate for initial
investment of about $1,000,000 has been reported  by Amana for retooling to
produce low-NO  furnaces capable of meeting NO  levels of 12 ng/J
            (\                                 ^
(0.028 lb/10  Btu).  Annualized cost spread over  20 years to the
consumer was reported at approximately $17 per furnace, or a cost
effectiveness of $1.80 per kilogram ($0.80 per pound) of NO  reduced
                                                           A
(Reference 5-4).  A more recent estimate for capital cost indicates  that

                                    5-14

-------
the HTM would cost approximately $100 more to the consumer than a
conventional warm air and air conditioning unit of comparable size
(Reference 5-11).
       The incremental equipment cost for a new modulating warm air
furnace has been reported in  the range of $50 to $250 (References 5-4 and
5-7).  Ranges in incremental  costs of pulse combustion burner and
catalytic burners have been estimated by Putnam, et a!.. at $300 to $600
and $150 to $250, respectively, for applications in flue gas condensing
systems.  The incremental cost of a radiant burner (surface combustion)
was estimated to be $100 to 200 above that of a comparable noncondensing
system  (1979) (Reference 5-7).  Because both the pulse and surface
combustors and catalytic burner for domestic gas-fired heating are not
commercially available, these cost estimates are considered preliminary.
       A yearly service call  to readjust residential furnaces for low
smoke, CO and HC emissions and high efficiency was estimated at $33 to $55
(1976) for oil-fired  units (References 5-12 and 5-13).  This cost, which
is based on estimated labor for nozzle cleaning or replacement, filter
changes and excess air adjustment would be slightly less for gas-fired
furnaces.
       Since both the Amana and Bratko burner designs maintain good
combustion efficiency at low  excess air levels it is expected that NO
                                                                     /\
reductions with these controls also contribute to a reduction in energy
requirement for residential heating systems.  While control of combustible
emissions with burner servicing may increase energy requirements slightly
through increases in  excess air setting, the overall energy impact of CO
and HC emission control for existing residential space heating equipment
is considered minimal.
5.2    EMISSION CONTROL ALTERNATIVES FOR OIL-FIRED RESIDENTIAL SYSTEMS
       Oil-fired residential  and commercial heating systems emit NO  ,
                                                                   /\
HC, and CO as well as particulates and smoke.  Emission levels of these
pollutants are generally higher than those from gas-fired  units.  Air
pollutant control efforts for oil-fired residential equipment have been
directed at controlling combustible emissions, smoke and particulate
'(soot) as well as NO  through advanced burner and firebox  design and
                    A
improved maintenance  procedures.  NO  controls which did not maintain
                                     5-15

-------
low smoke and hydrocarbon emissions were generally not viewed by
investigators as reasonable alternatives.
       This section discusses control alternatives to reduce these
pollutants for distillate oil-fired residential  heating systems  and
commercial size boilers burning distillate or residual oil.   Emphasis is
placed on NO  control technology for residential furnaces;  however,
            /\
control technology for other criteria pollutants and NOX control
techniques for commercial size hot water or steam boilers are also
discussed.
5.2.1  Nitric Oxide Control
       NO  control technology development for residential oil-fired
units was initially sponsored by the EPA and the American Petroleum
Institute (API) (Reference 5-14).  Control alternatives developed since
these early studies include primarily new burner and firebox designs.  The
most promising control alternatives for residential heaters include:
       •   Flame retention burners
       t   Controlled mixing burner head
       •   Integral furnace design using controlled mixing  burner head
       •   Blueray burner
       •   M.A.N.  burner
With the exception of the controlled mixing head and integral furnace
design, all other controls are commercially available or nearly  so.  The
controlled mixing  burner head and furnace are undergoing field tests  to
ascertain their performance, reliability and environmental  impact. These
controls are discussed in the following subsections.
       NO  control technology for commercial size hot water or steam
         A
boilers is less advanced than for residential systems.  However, several
control alternatives investigated for small industrial boilers during
recent EPA sponsored field studies (References 5-15, 5-16 and 5-17) may be
applicable to the commercial-size units of the same design.   For example,
the commercial size firetubes are very similar to the small  packaged
industrial size firetubes.  NO  control techniques that have been
                              A
investigated for industrial firetube boilers include (References 5-15
'through 5-18):
       •   Low excess air (LEA)
       t   Flue gas recircu1 ation (FGR)

                                    5-16

-------
       •   Staged combustion air  (SCA)
       t   Low-NO  burners  (LNB)
                 A
       Although F6R and SCA are very effective in reducing NOV, both
                                                             y\
techniques may be either technically impractical or too costly for
application on small commercial units.  These boilers are generally
operated unattended with heat  loads changing frequently.  A low NO
                                                                  A
burner for application on packaged boilers with heat input capacity of
less than 2.9 MW (10 x 10  Btu/hr) is currently under development
(Reference 5-19).  Another LNB, developed and currently being field tested
by TRW Corporation, may be the most feasible alternative for significant
NO  reductions for these units.   However, the TRW LNB development has
                                                     fi
been limited to burner capacity above 2.9 MW (10 x 10° Btu/hr).  TRW
representatives indicate that  if  a market for NO  control for commercial
                                                /\
steam and hot water boilers develops, TRW may then investigate the
potential for scaling down the industrial size burner to a commercial unit
with heat-input capacity as low as 0.15 MW (0.5 x 106 Btu/hr)
(Reference 5-20).  Additional  information on combustion modification NO
controls for small industrial package boilers with potential  application
to commercial size boilers  is  given in References 5-21 and 5-22.
5.2.1.1  Flame Retention Burners
       The flame retention burner head has been commercially available for
some time.  Residential burners using flame retention devices accounted
for over 10 percent of the oil-fired burner designs for space heating
equipment in 1972 (Reference 5-23) and essentially all small  burners
currently installed with new furnaces and boilers are flame retention
types.  These devices in the form of plates, grids or cones produce a high
swirling flow which holds the flame at the retention ring.  Local
recirculation zones reduce smoke  emissions and allow for operation at low
excess air levels.
       Laboratory experiments have shown that most flame retention burners
increase NO  emissions (References 5-12 and 5-23).  In a study on the
effect of burner type on emissions from a residential warm air furnace,
Hall reported NO  emissions from  a conventional high pressure atomizing
                                    fi
burner at 37 ng/J as N02 (0.09 lb/10  Btu).  Ten commercially
available flame retention burners were tested in the same furnace,
                                    5-17

-------
 producing NOX emissions  in the range 26 to 59 ng/J as N02 (0.06 to
 0.14  lb/106 Btu)  (Reference 5-12).  Only the ABC Mite burner model
 illustrated in Figure 3-6 (see Section 3) was found to reduce NOX by
 about  30 percent, from 37 to 26 ng/J, while also reducing smoke emissions
 from  a Bacharach  number  of 2.9 to 2.0 (Reference 5-12).  During a field
 investigation of  residential systems, Barrett, et al., reported NOX
 emissions from conventional burner systems, in "as-found" conditions, in
 the range of 47 to 85 ng/J as N02 (0.11 to 0.20 lb/106 Btu).  NOX
 emissions from domestic  heating systems equipped with flame retention
 burners ranged between 48 and 88 ng/J as N02 (0.11 to 0.21 lb/106 Btu)
 (Reference 5-23).
       In general, most  flame retention devices are desirable for all
 conventional high pressure atomizing gun burners because they allow for
 operation at low  excess  air levels and stay tuned longer.  These two
 characteristics improve  furnace efficiency and reduce overall emissions
 through reduced fuel consumption.
 5.2.1.2  Controlled Mixing Burner Head
       A controlled mixing burner head for retrofit application to
 residential oil heating equipment was developed by Rocketdyne Division of
 Rockwell International under EPA sponsorship (Reference 5-24).   The
 principal characteristics of this burner head are:  (1) no flame retention
 device, (2) choke diameter related quantitatively to the firing rate, and
 (3) oversize internal peripheral vanes oriented at 25 degrees relative to
 the blast tube axis (Reference 5-25).  The choke diameter was attributed
 to reducing N0x by promoting a uniform one-dimensional (plug) flow while
 the internal vanes maintained low carbonaceous pollutant emissions at low
 excess air operation.  Figure 5-7 illustrates  the details of this, burner
 design.
       Results of laboratory studies  indicated that the controlled mixing
 burner head design is feasible for commercialization and could be
 retrofitted on existing residential  space-heating equipment which
 presently use conventional high pressure atomized oil burners.   Sheet
metal  stamping was found to be the best fabrication method for commercial
 production of the burner head.  The burners were found to operate
successfully with long life potential.  NOX reduction capability was
                                    5-18

-------
(a) External View
    5DZ21-8/6/73-S1
 (b) Optimum  1 al/s
     Burner Head
5DZ21-8/6/73-S1A
   Figure 5-7.  1 ml/s (gph) controlled mixing  low-emission
                residential oil  burner (Reference  5-25).
                             5-19

-------
Investigated by testing two commercially available warm air furnaces
retrofitted with the EPA/Rocketdyne burner head.  Results of the tests are
illustrated in Figure 5-8.  Based on these data, Combs and Okuda estimated
that retrofit of this burner head design would reduce NO  emissions by
                                                        A^
20 percent with potential increases in season-averaged thermal efficiency
as high as 5 percent (Reference 5-25).
5.2.1.3  Integral Furnace Design With Controlled Mixing Burner Head
       Although appreciable NO  reductions (20 percent) were achieved
                              /\
with the controlled mixing burner head, minimum NO  emissions
                                                  J\
necessitated optimization of the entire furnace system.  Under the same
EPA furnace development program, Rocketdyne developed a cylindrical
combustor to be used with the low-NO  burner to produce a low emission
                                    /\
integral furnace design.  A NO  emission level of 0.5 g/kg (1.0 Ib/ton)
                            fi
or about 11 ng/J (0.03 1b/10° Btu) heat input was set as the emission
goal for the program (Reference 5-25).  The main features of the combustor
design needed to achieve this level were identified as follows
(Reference 5-26):
       t   Removal of approximately 20 percent of the heat input from the
           firebox based on the higher heating value of the oil
       •   An inside combustor diameter of 0.28 m (11 inches) or greater
           for a 1.05 ml of oil/s (1.0 gph)
       •   Long combustion chamber length for long residence time to
           prevent formation of combustible emissions at low excess air
           levels
       The overall system utilizing the EPA/Rocketdyne combustor and
burner head plus additional energy saving features, is illustrated in
Figure 5-9.  As shown, an air-cooled finned firebox was selected.  The
figure also highlights other important features. Most important are the
controlled mixing (labelled optimum in the figure) burner head for
low-NO  emissions at low excess air and the standby draft control used
      A
to reduce energy losses during furnace "off" cycle.  During laboratory
tests the prototype furnace reduced NO  emissions by 65 to 70 percent to
                                      A
about 0.63 g/kg (1.26 Ib/ton) level, short of the original program goal.
Steady-state and cyclical efficiencies averaged nearly 85 and 75 percent
respectively (Reference 5-26).
                                    5-21

-------
                                        Smoke < 1

                                  	 Smoke > 1
                        W1ll1«mson Burner Head
                                     Commercial Proto-
                                     type Optimum Head
                                1.5


                         StolcMometHc Ratio


              A.   Williamson  1166-15 Furnace  System
       I
J.D


2.5


2n

1 5












i


















/

-
i




^ Ci
\
^
'
/

1




irrle
k
S*—
^»«
\
S
I
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	 Smoke * 1
	 Smoke >_ 1

p Bur





•ner »

-*x
^

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n Hea





X

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type

1.0 1.5 I.
                         Sto1ch1owtr1c Ratio
               B.   Carrier  58HV-156 Furnace  System


Figure  5-8.   Comparative NO emissions for  the controlled mixing
              EPA/Rocketdyne burner head  as  a retrofit  device in
              two warm-air  furnaces (Reference 5-26).


                                5-22

-------
Y1
ro
u>
                                                                        SEALED COMBUSTION AIR SYSTEM
    STANDBY DRAFT  CONTROL
                                                                               COMBUSTION AIR FILTER
     QUIET PULSE FREE STATOR
OPTIMUM BURNER HEAD
                                                                           AIR COOLED FINNED FIREBOX
                                Figure 5-9.   EPA low-emission integrated furnace components

                                             (Reference 5-28).

-------
       Recently six units based on this prototype design were installed in
eastern U.S. residences and operated during the 1977-78 heating season.
During reported tests, NOX emissions were measured at 0.65 g/kg
(1.30 Ib/ton) of fuel burned.  This NO  level corresponds to an average
                                      /\
reduction of 65 percent from levels measured with conventional  furnace
designs.  Steady-state and cyclical efficiencies averaged 84 and
74 percent respectively and, in general, did not degrade over the heating
season (Reference 5-29).  These high efficiencies translated to
18.5 percent fuel savings when compared to the two prior heating seasons.
A second field test program is under way to assess the reliability of the
system and supplement the existing data base.
5.2.1.4  Blueray Burner
       In 1973, the Blueray System Incorporated, Jericho, New York,
patented a low emission high efficiency oil-fired warm air furnace (U.S.
Patent No. 3,741,166).  The Blueray furnace uses a new burner design which
produces a soft, even blue flame instead of the conventional orange-yellow
flame.  Figure 5-10 illustrates a schematic of the Blueray burner
assembly.  Combustion gases representing about 50 percent of the
stoichiometric air requirement are recirculated to produce smoke-free,
blue flame combustion at  low excess air.  Most luminous soot particles are
eliminated during the reburning.  Because the blue flame burner is matched
to the combustion volume  to obtain the desired recirculation pattern, the
Blueray system is available only as a burner-furnace package.  Retrofit to
existing furnaces is not  practical.  The "blue flame" burner is sold in
warm air furnaces in two  firing ranges, 0.63 to 0.79 ml/s (0.60 to
0.75 gph).
       Nitric oxide emissions from a 0.79 ml/s (0.75 gph) furnace were
measured at between 25 and 35 ppm or about 0.41 g/kg (0.82  Ib/ton) of fuel
oil burned.  CO emissions from the same furnace were 15 to 25 ppm and UHC
3 to 5 ppm, while smoke emissions were nearly zero (Reference 5-30).  In
addition to the low-NO  operation, the Blueray furnace operates at high
                      ^
steady-state efficiency averaging 83 to 84.5 percent.  The furnace
compactness and low operating noise are also desirable features.
       In 1974, Underwriters Laboratory (UL) certified the 0.63 and
0.79 ml/s (0.6 to 0.75 gph) furnace as meeting the UL and ANSI standards.
Since then over one thousand furnaces have been installed in many eastern

                                    5-25

-------
                               Vapon
                                  Zone
 Electrodes    I "
                          Oil  Spray
                              Combustion  Zone
 Supply
 Air Supply
                                 Flame
                                 Front
Burner Blast
    Tube
                            Recirculated
                            Products  of
                            Combustion
     Figure 5-10.
Schematic illustration  of the Blueray head assembly
(Reference 5-30).
                                    5-26

-------
states.  Recently, under  the current NO  Control Environmental
                                       A
Assessment  (NOX EA) program, one such furnace was field tested
(Reference  5-31).  Nitric oxides, CO and UHC emissions were measured
during continuous  and cyclical operation.  Cycles consisted of 10 minutes
on  and 10 minutes  off periods.  Pollutant emissions in ppm measured with
20  percent  excess  air are listed below:

                                Cyclical          Continuous
                                Operation         Operation
               NO, average           11               16
               NO, peak              16               16
               CO, average          160               25
               CO, peak           2,000               25
               UHC, average          23                0
               UHC, peak            390                0

Cyclic NO emissions (11 ppm uncorrected) correspond to about 0.35 g/kg
(0.70 Ib/ton) of fuel burned and are lower than those reported in
Reference 5-30.  Section 6 presents trace elements and organic emission
data also obtained during the NO  EA test program on the Blueray
                                /\
furnace.  These data are then compared with recently published test data
obtained by TRW for conventional distillate oil-fired residential furnaces
5.2.1.5  M.A.N. Burner
       The  M.A.N. burner was developed and licensed by the German Research
and Testing Laboratory for Air and Space Travel.  Figure 5-11  illustrates
a schematic of the burner.  Hot combustion gases are recirculated to
achieve complete combustion in a manner similar to the Blueray system.
The main difference between the two burners is that the Blueray burner
uses an "external" gas recirculation system which requires an air tight
combustion  chamber to prevent air leaks.  The M.A.N. burner, however,
recirculates the hot combustion gases internally within the blast tube.
This design feature may permit retrofit installation of the burner on
existing warm air furnaces.
       The M.A.N. burner, which is commercially available in Europe in
firing capacities ranging from 0.53 to 0.80 ml/s (0.5 to 0.75 gph) is
being tested at the EPA Industrial Environmental Research Laboratory

                                    5-27

-------
                               Seal
        Oil  [
                    Damper
Mixing
 Pipe
Burner
 Pipe
        Figure 5-11.  Schematic of the M.A.N. residential oil-fired
                      rocketburner (Reference 5-32).

(IERL) (Reference 5-33).  Manufacturer estimates of NO  emissions range
                                                      /\
from less than 20 to 50 ppm.  Lowest NOX emissions are obtained with an
air-cooled blast tube.  Reported CO emissions are less than 100 ppm and
smoke Bacharch number less than 1.0 (Reference 5-33).
5.2.2  Carbon Monoxide and Unburned Hydrocarbon Control
       Emissions of CO and UHC from residential space  heating equipment
are primarily a function of fuel consumption, cycle frequency, and excess
air levels.  In general, CO and UHC emission reduction can be accomplished
by:  (1) reducing fuel consumption with increased overall system
efficiency or reduced heat demand, (2) reducing the number of on-off
cycles which cause combustible emission peaks, and (3) assuring proper
normal excess air setting with tuning and scheduled burner maintenance.
The following subsections describe the implementation  of these control
approaches and review published performance data.
5.2.2.1   Reduction in Fuel Consumption
       Increased steady-state and cyclical  thermal efficiency for
residential oil-fired heaters can best be achieved with integrated burner
and combustor system design.  Advanced concepts such as the flame
                                    5-28

-------
retention burner and the Blueray or EPA/Rocketdyne furnace design increase
steady-state efficiency primarily by achieving complete combustion at low
excess air.  This increases efficiency by 5 to 10 percentage points
compared to conventional furnaces (Reference 5-26).  Overall seasonal
emissions are reduced proportionally to the fuel saving.
       Reduction in fuel consumption can also be accomplished by
installing energy saving devices such as chimney or duct dampers.  These
devices increase cyclical furnace efficiency by reducing heat loss during
the standby portion of the heating cycle.  Standby heat losses are caused
by cooling of the combustor by natural draft air circulation.  During a
field study performed in Canada, chimney dampers reduced seasonal CO
emissions from two warm air furnaces by 2.4 and 19 percent, respectively
(Reference 5-34).  The difference in performance between the two sources
was caused by variation in cycling frequency.
       A third and most straightforward method of reducing fuel
consumption and thus CO and UHC emissions, is to turn down the thermostat
or increase thermostat anticipator settings.  Overnight thermostat cut-
back by 3 to 5 K (5 to 9°F) reduced seasonal CO emissions by 9 to
27 percent (Reference 5-34).  The relative performance of reduction in
fuel consumption on seasonal CO and UHC emissions depends highly on the
number of cycles the residential furnace or boiler undergoes.  Furnaces
with a high cycle frequency have much higher combustible emissions than
those furnaces which are cycled less frequently.  Thus, reduction in fuel
consumption is less effective in reducing seasonal CO emissions  from
furnaces which cycle frequently during the entire heating season
(Reference 5-34).
5.2.2.2  Reduced Cycle Frequency
       Reduced firing rate capacity and changes in thermostat anticipator
setting are the principal methods to reduce the cycling frequency of
residential heating systems.  Reduced firing rate causes the furnace to
operate for longer periods to meet load requirements.  Changes in
thermostat anticipator setting can result in a wider temperature "window"
in which the furnace is on and thus reduces furnace cycle frequency.  To
achieve this increase in temperature window, the anticipator setting is
either increased or decreased depending on the thermostat wiring
arrangement.  Both methods of reduced firing rate and change in

                                    5-29

-------
anticipator setting independently reduce the number of times the burner is
ignited and shut off, thus reducing overall CO and UHC emissions over an
entire heating season.  Furthermore, overall furnace heating fuel
efficiency to the home is increased.
       Existing oil-fired residential heating systems are generally
oversized with respect to the residential load demand.  A recent study of
26 residential systems (six forced warm air, 16 hot water, and four steam
or heat transfer fluid) in the Boston area by Bonne et a!., revealed that
the excess capacity of these residential oil burners averaged 147 percent
(i.e., 247 percent of design capacity) (Reference 5-35).  Twelve oil-fired
burners had a minimum capacity in the range of 1.05 to 1.42 ml/s (1 to
1.35 gph) and 14 others had a capacity of greater than 1.42 ml/s
(1.35 gph) (Reference 5-36).  When a reduction in firing rate of these
units was attempted by reducing the size of oil nozzles 28 percent,
however, an increase in excess air of about 37 percent was found necessary
to prevent excess smoke emissions.  Soot formation was promoted by reduced
atomization efficiency with the smaller nozzles.   Also smaller burners
tend to become plugged after short operating periods.   Overall,  Bonne, e_t
al., concluded that, even when accounting for the negative aspects of
retrofitting smaller capacity wastes on existing  oversized units (such as
increased excess air, increased electrical  energy consumption by the
blower motor, oil pump and system recirculating fan/pump due to longer
on-times, and higher furnace infiltration losses  due to increased air flow
through the stack draft diverter), the net result was  a modest decrease in
seasonal fuel consumption and cost for space heating by 5.2 and
3.7 percent, respectively (Reference 5-36).
       Janssen, et al., investigated the feasibility of a thermal aerosol
generator as a residential oil burner which could operate efficiently at
firing rates reduced to as low as 0.42 ml/s (0.4  gph)  while using an
excess capacity nozzle in the range of 0.89 to 1.31 ml/s (0.85 to
1.25 gph).  Reducing the oil flow instead of using smaller 0.42 ml/s
(0.4 gph) capacity pressure atomizing nozzle eliminates the potential
plugging problem of very small capacity nozzles (Reference 5-37).  In the
thermal  aerosol burner the distillate oil was heated to over 373 K
(212°F).  The use of heated oil  improves atomization (i.e., smaller oil
drops and thus better fuel air mixing), at low pressure and reduced firing

                                    5-30

-------
rate.  The thermal aerosol oil burner achieved good atomization with low
CO and UHC emissions at 0.42 ml/s (0.4 gph) oil flowrate (representing a
53 to 68 percent nozzle capacity reduction) and low excess air.  Heating
the fuel was also found to lower emissions during start-up.  Fuel oil
heated to 423 K (302°F) produced zero smoke in less than 1.5 minutes
after ignition (Reference 5-37).  During most tests, NO  emissions also
decreased with increasing fuel oil temperature and pressure.
       In another study, Hayden e_t al., reduced the firing rate on one
furnace, thus reducing seasonal number of cycles from 3,400 the previous
season to 3,301 during the test season.  Seasonal  CO emissions were
reduced 14.2 percent (Reference 5-34) with approximately 9 percent of this
reduction attributable to fuel savings.  Reducing the cycling frequency
also generally significantly improves the overall  furnace efficiency.
"Off" cycle heat losses due to the buoyancy induced drafts in the stack
and combustion system are reduced due to the fewer numbers of standby
periods.  When Katzman and Monat reduced the firing rate of 18 oil-fired
residential heating systems by 36 percent, the resulting average increase
in seasonal efficiency was 14 percent (Reference 5-38).  Overall seasonal
mass emissions are generally reduced through a reduction in fuel
consumption.
       Increased thermostat anticipator setting showed a dramatic effect
on cycling frequency and seasonal CO emissions during tests on oil-fired
residential heaters (Reference 5-34).  Two hot water hydronic systems with
unusually high cyclic frequency (approximately 11  to 22 thousand cycles
per season) were tested with an increased anticipator setting of the
Honeywell thermostats.  The total number of cycles decreased an average of
55 percent.  CO was reduced over 40 percent when compared to total
seasonal emissions of the previous heating season.  These dramatic CO
emission reductions are indicative of the importance of combustible
emissions during cyclic operation.
5.2.2.3  Burner Tuning and Maintenance
       Several investigators have shown that CO and UHC emissions can be
reduced significantly by adjusting or tuning existing burners, and by
replacing worn-out burner components or entire furnaces.  One team of
investigators studied the emissions from 33 residential oil-fired units
during the 1970 to 1972 heating season (Reference 5-23).  Pollutant

                                    5-31

-------
emissions were measured in  the "as  found"  condition  and after tuning.   The
procedure for tuning included:
       •   Cleaning and adjusting the ignition  electrodes
       •   Cleaning the blast tube  and blower  shell
       •   Cleaning or replacing the nozzles
       •   Cleaning or replacing the oil  filter
       0   Sealing air leaks at the inspection  door,  around the blast tube
           or at other easily accessible  locations
       t   Changing the draft regulation  setting
Three of the 33 units tested were found to be  in such poor condition that
they had to be replaced.
       Table 5-3 summarizes the reductions in  mean  pollutant emissions
that could be accomplished  by identifying  and  replacing the units
obviously in poor condition and by tuning  the  remaining units.
Combustible emissions were  reduced  substantially only by replacing the
three furnaces found in poor condition.  Actual tuning added only
3 percent reduction for UHC and 16  percent for CO.   Barrett, et a!., also
showed that overall thermal efficiency for the units  tested increased
1.7 percent on the average  (Reference 5-23).

 TABLE 5-3.  EFFECT ON MEAN EMISSION OF IDENTIFYING AND REPLACING RESIDENTIAL
             UNITS IN POOR  CONDITION AND  TUNING (Reference 5-23)
Pollutant
Smoke
CO
HC
N0x
Filterable Partic-
ulate
Reduction in Emissions, percent
Step 1
Replacements of
Worn-Out Units
65
87
No Change
17
Step 2
Replacement of Worn-
out Units and Tuning
of Remaining Units
59
81
90
No Change
24
Improvement
Due Only to
Tuning
59
16
3
0
7
                                    5-32

-------
       As indicated in Table 5-3, tuning has essentially no effect on NO
emissions except for the  indirect reduction due to  increased thermal
efficiency and hence reduced fuel consumption.  Tuning was found to be most
effective for smoke emissions.  The overall dramatic reduction  in emissions
accomplished simply by replacing 9 percent of the units tested  indicates that
unnecessary combustible pollutants are emitted from old furnaces with worn-out
or damaged burners.  Hall, et^ aj_._, and Barrett, e_t aj_._, estimated that 9 to
30 percent of existing oil-fired residential burners are worn out and in need
of replacement (References 5-12 and 5-23).  Lifetime of an oil-fired
residential furnace averages 15 years  (Reference 5-13).
       In addition to reducing CO and  UHC emissions through burner tune up, an
annual maintenance program is suggested for low emissions  and maximum thermal
efficiency throughout each heating season (Reference 5-12).  Performance of
residential oil-fired heaters and, to  some extent, commercial boilers
deteriorates with time.   The decrease  in performance if unchecked, can lead to
very poor operation.  As  much as  10 percent efficiency drop has been measured
over a period of 10 weeks on one experimental furnace  (Reference 5-12).  One
reason is that some of the soot which  is formed during inefficient operation
adheres  to the heat transfer surface.  Soot accumulation will eventually lead
to reduction in heat transfer, higher  stack temperatures,  and increased
emissions due to increased fuel usage.
       EPA Guidelines for tuning and maintenance of oil-fired residential  and
commercial heating systems recommend the following  (References  5-39 and 5-40):
       t   Inspect fuel oil nozzle; clean or replace if necessary
       t   Replace or install in-line  oil filter
       •   Clean heat transfer surfaces of soot or  other deposits
       t   Seal air leaks
       •   Set fuel oil pressure to manufacturer's  recommendations
       t   Set fuel oil temperature to provide manufacturer's recommended
           viscosity (only for large commercial units  burning other than
           distillate oils)
       •   Assure timely  shut-off of fuel flow and  proper  ignition without
           excessive emissions
       •   Set excess air to recommended COo  levels without  incurring
           excessive CO or smoke emissions
                                     5-33

-------
       These maintenance procedures performed by skilled service personnel
will ensure that residential and commercial oil-fired heaters and boilers do
not cause unnecessary combustible emissions and that high thermal efficiency
of the unit is maintained.
5.2.3  Smoke and Particulate Control
       Essentially all oil-fired residential heating units are fired with
No. 2 distillate oil.  Particulate emissions from the burning of this grade of
oil are usually small compared with those from units fired with residual oil.
High smoke or particulate readings with distillate are mostly due to improper
air-to-fuel ratios, improper draft, worn-out burner components, or poor burner
and combustion chamber design.
       As with CO and UHC control, an effective and practical technique to
reduce particulate and smoke emissions from residential  oil  burners is to keep
them well maintained.  Significant improvements can also be  obtained through
the use of new, well  designed burners and combustion chambers.   Also, energy
saving devices which  improve steady-state efficiency and reduce cyclic
frequency reduce seasonal particulate and smoke emissions indirectly through
reduced fuel consumption.
       In general, those controls discussed in the previous  section for CO and
UHC emissions are also effective in reducing smoke and particulates from
residential heaters.   In addition, delayed action solenoid oil  valves have
been tested successfully to reduce smoke emissions during start-up and
shut-down periods when carbonaceous emissions are highest.  This control is
discussed in Section  5.2.3.4.
5.2.3.1  Burner Tuning and Maintenance
       In Battelle's  tests of residential and commercial heating units
(Reference 5-23), tuning of the serviceable units reduced the mean values of
the Bacharach Number  considerably.  Results of these tests for smoke emissions
are summarized in Figure 5-12.  The mean Bacharach Number was 3.2 for the "as
found" condition.  After tuning, the mean smoke number was reduced 59 percent
to 1.3 (see Table 5-3).  Moreover, after tuning,  all of the  serviceable units
could have complied with a standard of Bacharach  No. 3 and nearly 90 percent
could have even complied with a level of 2.  Reduction in emissions of
filterable particulate attributed to tuning averaged 7 percent. The guidelines
for tuning and maintenance discussed in the previous section are also valid
for control of smoke  and particulate emissions.

                                    5-34

-------
          i-
          o>
          ID


            4
                 As-found •

                    Tuned ©
               Mean Values

              • - As Found
                   Tuned
                                          °
                                      GO
                            OOOQOOOO
                            40       60

                            Percent
                            80
                                                  TOO
Figure 5-12.
Distribution  of  smoke emission for  residential units

(Reference  5-23).
                                 5-35

-------
5.2.3.2  Burners and Combustion Chamber Redesign
       Advanced  low-NO  burners for residential oil-fired heaters are
also capable of operating at low excess air with essentially smoke-free
flue gas.  These burner designs rely on optimal choices for swirl over
velocity to obtain the desired turbulence level and residence time
(EPA/Rocketdyne controlled mixing burner).  In addition, many use either
internal or external flue gas recirculation for complete burnout (Blueray
and M.A.N. burners).  Flame retention devices which produce a more stable,
compact and intense flame have also been demonstrated to reduce smoke and
particulate emissions.  In one study, one type of flame retention burner
emitted less smoke than the conventional unit (average Bacharach Number of
1.2 for the retention head versus 2.9 for the others) (Reference 5-12).  A
set of field test results also showed that smoke and particulate were
lower for retention head burners than for conventional designs.  Smoke
emissions were reduced 26 percent and filterable particulate emissions
were reduced 50 percent on the average (Reference 5-23).
5.2.3.3  Reduced Fuel Consumption and Reduced Cycle Frequency
       As indicated in the discussion for CO and UHC control, reduced fuel
consumption can be accomplished by a variety of methods.  Installation of
chimney or duct dampers reduced fuel consumption by 3 to 9 percent on two
warm-air furnaces, decreasing seasonal particulate emissions from 2.2 to
17.2 percent.  Overnight reductions in thermostat settings of 3 to 5 K (5
to 9°F) reduces seasonal  fuel  consumption by 7 to 15 percent and
decreased particulate emissions by about 12 to 24 percent (Reference
5-34).  Increased thermostat anticipator (resulting in longer on-times
reduced fuel consumption marginally, but the particulate emission
reductions were significant —  32 to 33 percent -- primarily caused by a
reduction in cyclic frequency of warm-air furnaces tested
(Reference 5-34).  Reduced firing rate resulted in seasonal  particulate
emission reductions of only about 4 percent.  These were caused by a
9 percent reduction in fuel  oil consumed and a 3 percent reduction in
cycling frequency (Reference 5-34).
5.2.3.4  Delayed Action Solenoid Valve
       Katzman and Weitzman found that the installation of delayed action
solenoid valves reduced the average smoke number from 6.3 to 2.3 during
furnace startup and 8.3 to 0.7  during shutdown periods (Reference 5-13).

                                    5-36

-------
During start up, the solenoid delayed the opening of the oil  valve until  the
burner air blower had reached full speed.  This prevented the poor startup
performance caused by insufficient combustion air and mixing.  During shut
down, the delayed oil valve closed off immediately providing  a clean  flame cut
off.  Without the valve, the speed of the blower generally decreased  to
approximately 900 rpm (25 percent of capacity) before the oil flow was
actually shut off.  Smoke emissions during start up and shut  off periods
without the delayed oil  valve ranged from Bacharach numbers of 5 to 9
(Reference 5-13).
5.2.4  Cost and Energy Impact of Controls
       Reported control  costs for oil-fired residential heating systems vary
significantly according to the type of control and application.  For  example,
the 1976 retrofit costs of NO  controls ranged from about $38 for the burner
                             A
head developed by Rocketdyne to about $339 for a reduced capacity
high-efficiency flame retention burner.  More recent differential costs of a
new low-NO  furnace, such as the Blueray or the Rocketdyne unit, range  from
          /\
about $100 to $250 over the cost of a conventional furnace.
       Although inflation has increased the cost of these controls over the
past few years since 1976, the cost of fuel oil has also risen even more
dramatically than the average rate of inflation has.  Therefore, the  energy
saving associated with most retrofit controls and new low-emission
high-efficiency furnaces is such that the initial investment  is often
recovered within the first two heating seasons.
       The volume production cost of the burner head by Rocketdyne was
estimated to be only $1.50 (Reference 5-25).  Including the installation  cost,
the total investment in 1976 was estimated at about $38 per burner.  Since the
burner head increases seasonal efficiency by about 5 percent  on the average,
the payback period should be rather short (i.e., generally less than  a year).
       As discussed in Section 5.2.1.1, retrofit of flame retention cone  heads
on existing high pressure gun atomizing oil burners was determined to be
feasible.  The cost and energy savings of retrofit installation of one flame
retention head with a new nozzle rated at lower firing capacity was also
estimated.  The average 1976 investment cost was estimated to be $45  on the
                                    5-37

-------
average and the energy savings would amount to approximately $110 for a
payback period of less than 1 year (Reference 5-13).
       The cost to retrofit a new flame retention burner with a reduced
firing capacity was estimated to require an initial investment of $339 in
1976  (Reference 5-13).  Accounting for inflation, this cost would increase
to about $385 in 1978.  However, the annual fuel oil saving was estimated
to average 2009 liters (531 gallons) when compared to fuel oil
consumptions of existing low-efficiency furnaces (Reference 5-13).
Considering that the cost of home heating oil  in 1978 was approximately
$0.20/1 ($0.80/gal) annual  savings would amount to about $400.  Therefore,
the payback period for the reduced capacity flame retention burner would
be approximately 1 year.
       Rocketdyne, along with EPA, has applied for a patent for the new
furnace system discussed in Section 5.3.1.2.  The incremental equipment
cost of this furnace compared with a conventional warm-air heater was
recently estimated to be about $250 (Reference 5-41).   Assuming an annual
heating oil bill of $1,000 per household and considering the reported
savings in fuel  consumption of about 18 percent, the payback period for
this  initial investment is  less  than 2 years.
       The Blueray furnace, equipped with the "blue flame" low-NO
                                                                 /\
recirculating burner is commercially available with over one-thousand
units already in place.  The cost of the Blueray furnace was estimated to
be about $100 more than the cost of a conventional  warm air heating system
(Reference 5-42).   This differential  investment would generally be
recovered in less  than a year.
       No cost information  is  available for the M.A.N. burner.  Foreign
manufacturers are  planning to introduce this burner design in the U.S.
Recently the burner has undergone tests at EPA laboratories.  Commercial
availability is  expected in 1980 (Reference 5-43).
       Tuning of a residential oil-fired furnace for low emissions and
high thermal efficiency was estimated to cost  $33 to $55 (1976) based on
the labor cost estimates by Katzman and Weitzman for installation of flame
retention cones  and nozzles and  adjustment of  combustion air flow
(Reference 5-13).   Since unit  efficiency generally increases with tuning,
this initial cost  is offset by savings in fuel consumption.  Manufacturers
and service organizations recommend that residential heaters be serviced

                                    5-38

-------
once a year, preferably at the beginning of the heating season
(Reference 5-12).
       Various other control techniques primarily aimed at reducing oil
consumption for residential heating and improving seasonal thermal
efficiency can be easily implemented by the homeowner.  Change of
thermostat anticipator setting if adjusted by the homeowner and manual
overnight thermostat cut-back require no cost and reduce energy
consumption plus reduce overall emissions.  Installation of positive stack
dampers requires some initial investment cost.  The recently reported cost
of installed automatic chimney dampers is $200 — $120 for the damper
(Reference 5-44). Thus, it can be estimated that the payback period for
this energy saving device could also be relatively short.
       In general, all air pollutant control techniques improve unit
thermal efficiency as well as reduce seasonal  NO  and combustible
emissions.  For this reason, the initial  investment required for new
burners, furnaces or scheduled tuning can in many cases be compensated
with reductions in fuel oil consumption which  translate to savings for  the
homeowner.
5.3    EMISSION CONTROL ALTERNATIVES FOR  SOLID FUEL-FIRED RESIDENTIAL SYSTEMS
       Solid fuel-fired residential and commercial systems include
hand-fired and stoker-fired systems plus  some  wood-fired stoves, furnaces,
and boilers.  Residential stokers are hopper fed or bin fed if equipped
with a mechanical underfeed system.  Larger commercial stokers can be of
the overfeed, underfeed and spreader type.  However, underfeed types are
most common.  Wood-fired residential furnaces  are essentially all
hand-fired.
       NO  emission control techniques for residential coal- and
         A
wood-fired heaters and boilers have not been widely investigated,
primarily because of the declining use of this equipment type in the
past.  Also, small coal-fired equipment is not amenable to extensive
modifications to control NO  emissions.  Excess air and overfire air
                           /\
injection in some units are the only feasible  control alternatives which
have some impact on the overall NO  emissions.  Wood heating has
                                  A
experienced a recent revival, and is the subject of a separate NOX EA
review to be published at a later date.
                                    5-39

-------
       Excess air reduction in residential coal-fired equipment is very
limited due to increases in carbonaceous emissions.  Overfire air
injection, only available with larger commercial size stokers, is only
moderately effective in reducing NO .  Overfire air which is generally
                                   J\
used to control smoke and HC emissions from volatile coal combustion was
found to be effective in achieving smokeless operation with some coals
containing 20 percent or more volatile matter (Reference 5-45).
       The emphasis of emission control from residential coal-fired
equipment has been placed on reducing smoke and other carbonaceous
pollutants.  As discussed in Section 4, the combustion of high volatile
bituminous coals  in small residential  systems produces high smoke and
particulate emissions.   A bituminous coal-fired furnace originally
developed in the  1940's was investigated in a program to identify clean
burning solid fuel-fired furnaces for residences.   This furnace developed
for Bituminous Coal Research,  (BCR) Inc. uses a cross-feed principle of
burning in which  both the coal  and combustion air move downward to the
"hearth" or cross-fed portion  of the fuel  bed.   Figure 5-13 illustrates a
new coal-fired furnace/boiler  based on the BCR  design.  This furnace can
operate with 60 to 65 thermal  efficiency and low smoke emission.   This
concept is applicable to boilers and space heating stoves as well  as
furnaces and can  also burn  wood or saw dust (Reference 5-47).
                                                 Nntntk
      Figure 5-13.
Schematic of the cross-feed combustion design for
coal-fired residential furnaces (Reference 5-46).
                                    5-40

-------
       Control techniques for wood-fired residential heaters have not been
developed to any great extent.  Since long term gas and oil  supplies will
continue to dwindle, wood represents a possible alternative  to coal burning
in home furnaces and residential and commercial boilers.  Recently, however,
the EPA has sponsored two test programs to quantify emissions and identify
potential control options for wood burning appliances (Reference 5-48).   In
the first test program Monsanto tested two air tight stoves  (one baffled and
the other unbaffled) plus one fireplace for criteria pollutant, trace element
and organics.  In the second program, which is just underway, Battelle is  to
identify equipment and operating parameters which affect emissions.  In
addition, the program will assess which of these parameters  can be safely
varied to reduce emissions.
5.4    SUMMARY OF MOST EFFECTIVE CONTROL ALTERNATIVES FOR RESIDENTIAL SYSTEMS
       In general, little of the NO  control  technology discussed
                                   A
earlier for gas- and oil-fired residential and commercial systems has been
implemented in the field.  Most emission control work for residential
heaters has centered around tuning and maintenance of existing equipment
or installation of new more efficient equipment for reduced  fuel
consumption and minimum visible emissions.  Tuning usually reduces CO, HC,
and particulates (smoke), however, without much effect on NO
                                                            /\
emissions.  New furnace concepts utilize advanced burner designs which
allow for efficient operation at low excess air.  Some of these burners
are also capable of low-NO  emissions.
                          J\
       The following discussion summarizes the performance and cost of
control techniques specifically aimed at reducing NO  emissions from
                                                    A
residential heaters.  Based on performance, commercial availability, and
cost, the best available NO  control techniques are identified.
                           A
Performance and cost of combustible emission controls for residential
heaters are also summarized.
5.4.1  Gas-Fired Systems
       Table 5-4 summarizes the performance of NO  control equipment for
                                                 A
natural gas-fired residential heaters.  Baseline uncontrolled emission
factors for the three major pollutants emitted from these sources are also
presented.  Additionally, steady-state and cycle efficiencies of baseline
or "as found" residential units and controlled residential units are also
                                    5-41

-------
        TABLE  5-4.   PERFORMANCE SUMMARY  OF LOW-NOX  CONTROL EQUIPMENT FOR  NATURAL GAS-FIRED RESIDENTIAL  HEATERS
ro
Control
Conventional
Units
Radiant Screens
Secondary A1r
Baffles
Surface Combus-
tion Burner
Amana (HTM)
Modulating
Furnace
Pulse C ambus tor
Catalytic
Comb us tor
Average
Operating
Excess Air
(percent)
40-120
40-120
60-80
10
NA
NA
NA
NA
Cyclic Pollutant Emissions
ng/J heat input
NOX
28-45
15-18
22
7.5
7.7
25
19-20
<5
CO
8.6-25
6.4
14
5.5-9.6
26
NA
NA
NA
UHCb
3.3-33
NA
NA
NA
NA
NA
NA
NA
Steady State
Efficiency
(percent)
70
75
NA
NA
85
75
95
90
Cycle
Efficiency
(percent)
60-65
70
NA
NA
80
70
95
85
1978
Installed
Control
Cost
c
NA
NA
J100-J200
J100-J300
over
conventional
furnace
J50-J250
over con-
ventional
furnace
J300-J600
J150-J2SO
C Dements
Emission factors from References
5-49 and 5-50. Costs include
Installation.
Emissions of CO and HC can increase
significantly If screen is not
placed properly or deforms.
Requires careful Installation. Best
suited for single port upshot
burners.
Not commercially available. Still
under development.
Commercially available design.
Spark ignited thus requires no
pilot.
Furnace Is essentially derated.
Thus it requires longer operation
to deliver a given heat load.
furnace
Currently being investigated by
A6AL. Efficiencies correspond to
flue gas condensing systems.
Still at the R&O stage. Efficiencies
correspond to flue gas condensing
systems.
                  of NO + NO? reported as NO?
              bUnburned hydrocarbons calculated as methane (CH4)
              CTypical costs of uncontrolled unit $500-$800
              dNA = not available.

-------
presented to highlight the general improvement in thermal  performance with
any of the NO  controls investigated.
             /\
       The Amana HTM and Bratko burner designs represent the most
effective control alternatives for gas-fired residential units.  Reported
NOX reductions are generally greater than 80 percent accompanied by
increases in thermal efficiencies of about 10 to 15 percent.  However,
recent tests with the Amana HTM combustor have not resulted in NO
                                                                 x
reduction efficiencies of 80 percent as previously reported by AGA.   New
tests have been scheduled (Reference 5-5).
       The Amana furnace is the only commercially available unit.  It is
generally used for combined heating and air conditioning of residences and
small commercial buildings.  The cost to the consumer of an Amana heater
is 20 to 40 percent more than the cost for a comparable unit.  No known
plans are under way to commercialize the Bratko burner.
       Pulse combustion in a residential system has been reported to emit
19 to 20 ng N02/J (0.044 to 0.047 lb/106 Btu) (Reference 5-8).  The
incremental cost of a pulse combustion burner was estimated in the range
of $300 to $600 for a condensing system with a seasonal efficiency of
95 percent (Reference 5-7).  A catalytic burner also with  a condensing
system and a seasonal efficiency of 85 percent was estimated to range
between $100 and $250 over the cost of conventional equipment
(Reference 5-7).  Both pulse and catalytic combustion for domestic heating
are, however, not commercially available.
5.4.2  Oil-Fired Systems
       Table 5-5 summarizes performance and cost of control equipment for
residential distillate oil-fired heating equipment.  These controls were
primarily designed for warm air furnaces, however, the new burner/firebox
technology of these systems may be applicable to residential hot water
heaters or hydronic boilers.
       The range in baseline NO  emissions reflect data reported by
                               /\
Barrett, et al., (Reference 5-23) and Hall (Reference 5-12) for nonflame
retention type burners.  Barrett, et al., suggested an average NO
                                             6
emission factor of 55 ng/J as NO,, (0.13 lb/10  Btu) for hot water and
warm air systems utilizing both conventional and flame retention burners
(Reference 5-23).  This emission factor compares to 61 ng/J as NOo
(0.14 lb/106 Btu) estimated by the EPA (Reference 5-50).

                                    5-43

-------
     TABLE  5-5.   PERFORMANCE  SUMMARY OF LOW-NOX  CONTROL  EQUIPMENT  FOR  DISTILLATE  OIL-FIRED RESIDENTIAL  HEATERS




Control
Conventional
Units




Flame Reten-
tion Burner
Head
Controlled
Mixing Burner
Head by EPA/
Rocketdyne
Integrated
Furnace Sys-
tem by EPA/
Rocketdyne

Blueray
"blue flame"
Bumer/Fumace
System
H.A.N.
Burner


Average
Operatin g
Excess air
(percent)
50-85





20-40


10-50



20-30




20



10-15


Cyclic Pollutant Emissions
ng/J heat input

a
NO/
37-85





26-88


34



19




10



10-25



CO
15-30





11-22


13



20




4.5-7.5



less than
30


UHCb
3.0-9.0





0.2-1.8


0.7-1.0



1.2




1.5-2.5



NA


Smoke
Number
3.2





2.0


less
than
1.0

less
than
1.0


zero



less
than
1.0

Particulate
7.6-30





NA


NA



NA




NA



NA




Steady State
Efficiency
(percent)
75





80-83


80



84




84



85




Cycle
Efficiency
(percent)
65-70





NA


NA



74




74



NA



1978
Instal led
Control
Cost
c





$52e


$436



$250 over
conven-
tional
furnace

$100 over
conven-
tional
furnace
NA






Comments
Range in NOX emissions is for residen-
tial systems not equipped with flame
retention burners References 5-12 and
5-23). Emissions for all other pollut-
ants are averages reported in References
5-23 and 5-50.
If new burner is needed as well as a
burner head, the total cost would be
$385. Cost is for 1978-79 heating season.
Cost of mass produced burner head only
about $1.50. Combustible emissions
are relatively low because hot firebox
was used.
Uses optimized burner head. For new
furnace installation only. Combustible
emissions are higher than with burner
head because of quenching in air cooled
firebox. Recent cost estimate.
New Installation only. Furnace Is
commercially available. Recent cost
estimate.

Both for retrofit or new installations.
Not yet commercially available in U.S.
Commercialization expected In 1980.
Ul
I
            of NO and N02 reported as NO?
        bUnburned hydrocarbons calculated as methane (CH/j)
        ^Typical costs of uncontrolled unit $650-$!,000
         NA = Not available.
        eOriginal costs reported for years other than 1978  were corrected for inflection
         using Gross National Product (GNP) implicit price  deflectors (Reference 5-51).

-------
       The most effective N0x controls for new residential oil burning
 is to use the Rocketdyne/EPA furnace system, the Blueray "blue flame"
 furnace and the M.A.N. burner.  Average NO  emission reductions with
                                          J\
 these controls range from 65 to about 80 percent depending on which
 uncontrolled emission  level is considered (i.e., 55 ng/J from Reference
 5-23 or 61 ng/J from Reference 5-50).  Both the flame retention and
 Rocketdyne/EPA controlled mixing burner head are desirable features for
 retrofitting existing  furnaces because they also allow for more efficient
 furnace operation with lower combustible and smoke emissions.  The
 controlled mixing burner head results in a modest NO  reduction of
                                                    X
 20 percent.  Although  most flame retention head burners produce high NO
                                                                       A
 emissions, a few result in some decrease in NO  from baseline levels.
       The Blueray furnace is the only equipment available commercially in
 the U.S.  The M.A.N. burner is commercially available only in Europe.
 However, this low-NOx  advanced burner is expected to enter the U.S.
 market in less than 1  year.  The range in NO  emissions for the M.A.N.
                                            A
 burner reflects test data reported for two firing configurations.   The
 lower emission factor  was obtained with an air cooled blast tube while the
 high emission factor is for an uncooled blast tube.  The M.A.N. warm air
 furnace system utilizes a cooled blast tube and firebox for low-NO
 emissions and high heat transfer efficiency.  The M.A.N. burner is an
 attractive control technique because it may be applicable to existing
 units.
       The Rocketdyne/EPA warm air furnace is still undergoing field tests
 to further demonstrate its reliability and improved performance.
 Presently, however, Rocketdyne has no immediate plans to market the
 optimized furnace design.  As Table 5-6 indicates, CO, UHC, and smoke
 emissions are equally  reduced with any of the N0x control equipment
 available.  Similarly, thermal efficiencies are improved reducing fuel
 consumption and seasonal  pollutant emissions.   Due primarily to  its
 commercial availability and low incremental cost, the Blueray furnace is
 considered the best available technology for new distillate oil-fired
 residential  warm air furnaces.
       Table 5-6 summarizes the various control techniques available for
 CO, UHC, smoke and particulate emission reduction from existing warm air
furnaces, water heaters,  or hydronic boilers burning distillate oil.

                                    5-45

-------
             TABLE  5-6.   PERFORMANCE SUMMARY OF  CONTROLS  FOR REDUCTION OF  SEASONAL COMBUSTIBLE, SMOKE AND
                            PARTICULATE EMISSIONS FROM  OIL-FIRED RESIDENTIAL  HEATERS
en
t
en
Control
Replacement of worn-out
units
Tuning and scheduled
seasonal maintenance
Dela>ed action solenoid
valves
Reduced excessive firing
capacity with conven-
tional burner
Reduced excessive
firing capacity with new
retention burner
Installation of positive
chimney dampers
Increased thermostat
anticipator setting
Overnight thermostat
cut-back (3-5K)
Percent Reduction (Average)
CO
(65)
(16)
NA
(14)
(14)
2.0-19
(11)
41-45
(43)
9.1-27
(17)
UHC
(87)
(3.0)
NA
NA
NA
NA
NA
NA
Smoke
NCa
(59)
60-90
(80)
10-38
(24)
80-85
(82)
NA
NA
NA
Particulates
(17)
(7.0)
NA
(3.7)
(3.7)
2.2-17
(10)
31-33
(33)
12-24
(15)
Percent
Improvement
in Fuel Saving
NAb
1 .7 percent aver-
age efficiency
increase
NA
5.6-2.5
(14)
14-39
(30)
3-9
0-2
7-15
1978
Installed
Control
Cost
$650-1000C
for new warm
air furnaces
$38-60c
J43C
$52C
J385C
J20QC
Minimal
Minimal
Comments
Nine percent of the existing residen-
tial heaters were found 1n need of
replacement. Recent cost estimates.
Tuning results in an Increase In effi-
ciency for some units and a decrease
1n efficiency for others.
Smoke emission reduction primarily
during start-up and shut-down.
Installation of flame retention head
cone plus modifications to reduce
firing capacity by about 36 percent.
Installation of new lower capacity
burner with flame retention head.
Firing capacity reduced by 43 percent.
Large variation In pollutant emission
reduction due to changes In furnace
cycle frequency. Recent cost estimates
Very effective for residential
units with high cyclic efficiency
Cost does not take Into account
improved home insulation which might be
necessary with thermostat cut-back.
                    *NC = No change
                    bNA = Not available
                    cCosts for material and labor are typical of New England area.  Original costs reported for years other than
                     1978 were corrected for inflation using Gross National Product (GNP)  implicit price  inflectors (Reference 5-51)
                     Parenthesis indicate arithmetic averages

-------
Again, the data in this table reflects primarily emissions data from warm
air furnaces but these controls are equally applicable to other
residential heating equipment.
       The first two techniques listed, replacement and tuning with
scheduled maintenance of existing furnaces, are aimed at reducing
combustible and smoke emissions and increasing system efficiency.  These
controls have essentially no effect on NO  emissions.  However, CO, and
                                         /\
UHC emissions are significantly reduced just by replacing worn-out units.
Smoke emissions are reduced significantly by tuning the equipment on a
yearly basis.  This indicates that most of the yearly combustible and
smoke emissions from oil-fired residential heaters are caused by very old
units in need of replacement or units in need of maintenance or tuning.
Delayed action solenoid oil valves reduce smoke emissions during start up
and shut down periods when smoke as well as CO and UHC emissions are
h i gh es t.
       The remaining control alternatives indirectly achieve a yearly
reduction  in NO  emissions firstly, through reduced equipment usage and
               /\
secondly, through improved fuel efficiency.  However, these controls are
aimed primarily at lowering seasonal combustible emissions and reducing
yearly fuel consumption.  Reduced excessive firing capacity and change in
thermostat anticipator setting to increase furnace on-time lower
combustible emissions by reducing cyclic frequency of the furnace.  These
controls lowered CO emissions by 14 to 43 percent respectively and smoke
24 and 82 percent primarily by reducing seasonal number of on-off cycles.
       In general, these alternative control techniques are very effective
in reducing the annual combustible and smoke emissions from residential
oil-fired furnaces.  With the exception of reducing excessive firing
capacity which might cause some operational problems with nozzle plugging,
all  control alternatives are available to the consumer.  Because all
reduce fuel consumption through improved efficiency or directly by
reducing equipment usage, there are some cost benefits as well as
environmental benefits associated with these controls.
5.5    EMISSION CONTROL ALTERNATIVES FOR COMMERCIAL SYSTEMS
5.5.1  Commercial  Heaters
       Application of control technology to commercial heating equipment
is very limited.   No information was found for low emission systems in

                                    5-47

-------
 indirect gas-fired equipment although there is a strong interest  in high
 efficiency appliances which implies  lowest excess air and complete
 combustion.  Compared to residential gas-fired equipment, a greater
 percentage of commercial warm air heaters or duct heaters utilize a forced
 combustion air burner as opposed to  a naturally aspirated burner.  These
 power burners usually have greater flexibility for excess air control
 while maintaining low CO and UHC emissions.
       Theoretically, the flame quenching and surface combustor concepts
 of the gas-fired residential burners could be implemented for commercial
 systems.  For oil-fired equipment, the EPA/Rocketdyne residential burner
 head design  implementing 25 degree air swirler vanes combined with optimum
 choke diameter (varying as the 0.4 power of the oil  flow) was found to
 minimize NO  emissions from burners with oil flow capacity as high as
           J\
 12.6 ml/s (12 gph).   NO  emissions with this burner design were
                       A
 generally 25 to 50 percent lower than those from commercially available
 burners with or without flame-retention devices and operating under
 similar conditions (Reference 5-52).
       Combustible emission controls listed in Table 5-6 could also be
 applied to commercial space heating equipment.   For example, reducing
 firing rate would be a viable alternative for commercial heating systems
 where the demand is  strongly cyclic.  Additionally,  increased thermostat
 anticipator setting or overnight thermostat cut-back could reduce annual
 emissions by amounts equal  to those obtained for residential units.
 5.5.2  Commercial Boilers
       Commercial or small  industrial boilers are mostly single burner
 packaged firetubes.   NO  control techniques for small  firetubes with
                                               fi
 heat input capacities less  than 2.9 MW (10 x 10  Btu/hr) have not been
 widely investigated.  However,  the similarity in equipment design between
 the small firetubes  and the larger industrial  size firetubes may allow
 application of similar combustion modification control  techniques.
Control  techniques investigated for industrial  boilers  which may be
applicable to the small  commercial  firetube units are listed in
Table 5-7.  Although N0x reductions represent controlled levels achieved
with  both industrial firetubes  and watertube designs,  as well as field
erected  and packaged boilers,  it may be possible that these NO
                                                              A
reductions could also be achieved with small commercial  firetubes.

                                    5-48

-------
    TABLE 5-7.
COMBUSTION MODIFICATION NOX CONTROLS FOR OIL- AND GAS-FIRED INDUSTRIAL BOILERS (Reference 5-22)
1 Control
Technique
None
Low Excess A1r
(LEA)
Staged
Combustion Air
Flue Gas
Recirculatlon
(FGR)
Flue Gas
Recirculatlon
plus staged
combustion
Load Reduction
(LR)
Low-N0x
Burners (LNB)
Description of
Technique
Baseline
Reduction of combus-
tion air
Fuel rich firing
burners with secon-
dary combustion air
ports
Reclrculation of
portion of flue gas
to burners
Combined techniques
of FGR and staged
combustion
Reduction of air and
fuel flow to all
burners in service
New burner designs
with controlled air/
fuel mixing and in-
creased heat dis-
sipation
Effectiveness of Control (Percent NOX Reduction)
Residual
67-362 ng/J
0-28; 11 average
or 10 ng/J/* 02
reduction
20-50
15-30
25-53
33% decrease to
25% increase
20-50
Distillate
011
45-107 ng/J
0-24; 11 average
or 10 ng/J/% 02
reduction
17-44
58-73
73-77
31* decrease to
17% increase
20-50
Natural
Gas
29-28 ng/J
71% decrease
to 85% in-
crease (10%
average
reduction)
5-46
48-86
Up to 76
32% decrease
to 82% in-
crease (10%
average
reduction
20-50
Range of
Application
Average excess 02
measured 5.8 percent
Generally excess 0?
can be reduced to 2.5%
representing a 3% drop
from baseline
70-90% burner stoi-
chiometries can be
used with proper
Installation of
secondary air ports
Up to 25-30% of flue
gas recycled. Can be
implemented on all
design types
Max. FGR rates set at
25% for distillate oil
and 20% for residual
oil
Applicable to all
boiler types and sizes.
Load can be reduced to
25% of max. Better Im-
plemented with improved
firebox design
New burners generally
applicable to all
boilers. More specific
Information needed
Comments
Emissions are from firetube and
watertube boilers not equipped
with preheaters.
Added benefits Included
increase in boiler efficiency.
Limited by increase 1n CO, HC,
and smoke emissions
Best implemented on new units.
Retrofit is probably not feasible
for most units. Generally
less effective for gas-fired
units. Doubtful application.
Best suited for new units. Costly
to retrofit. Possible flame In-
stability at high FGR rates. Most
effective on watertube units
Retrofit may not be feasible.
Best implemmented on new units.
Doubtful application of staged
combustion.
Technique not effective when It
necessitates an increase in excess
0;> levels, LR possible imple-
mented in new designs as reduced
combustion Intensity (enlarged
furnace plan area)
Specific emissions data from
industrial and commercial boilers
equipped with LNB are lacking
UD

-------
Available control alternatives include low excess air,  flue gas
recirculation and load reduction.  Low excess  air is  the only control
technique generally in use with boilers in this  size  category.  Low-NO
burners, if developed, could be the most cost-effective NO  control
technique besides LEA operation.
       Table 5-8 summarizes  NOX control  techniques  which have been
investigated for industrial  stoker coal-fired  boilers.   These controls
could also be potentially applicable to commercial  size stokers.   However,
as indicated, NO  reduction  performance data are very limited for
commercial boiler equipment  in the size category of less than 2.9 MW
(10 x 10  Btu/hr) heat input capacity.
                                   5-50

-------
                    TABLE  5-8.   COMBUSTION MODIFICATION  NO  CONTROLS  FOR  STOKER  COAL-FIRED

                                INDUSTRIAL BOILERS  (Reference  5-22)
en
i
en
Control
Technique
None
Low Excess
Air (LEA)
Staged
Combustion
(LEA + OFA)
Reduced Load
Description of
Technique
Baseline
Reduction of airflow
under stoker bed
Reduction of under
grate airflow and
increase of overfire
airflow
Reduction of coal and
air feed to the
stoker
Effectiveness of
Control (Percent
NOX Reduction)
150 ng/J
5-25
5-25
Varies from 49X
decrease to 25X
increase in NOX
(average 15X
decrease)
Range of
Application
Excess 0? measured
6.6-9.4X
Excess 02 limited
to 5-6X minimum
Excess 02 limited
5% minimum. Most
stokers have OFA
ports as smoke
control devices
but may need better
airflow control for
NOX reduction
Has been used down
to 25X load
Comments
Emissions are underfeed stokers
characteristic of low capacity
stoker-fed boilers.
Danger of overheating grate,
clinker formation, corrosion,
and high CO emissions
Need research to determine
optimal location and orienta-
tion of OFA ports for NOX
emission control. Overheating
grate, corrosion and high CO
emission can occur if under
grate airflow is reduced below
acceptable level as in LEA
Only for stokers that can
reduce load without increasing
excess air. Not a desirable
technique because of loss in
boiler efficiency

-------
                          REFERENCES FOR SECTION 5


5-1.   Thrasher, W. H. and D. W.  De Werth,  "Evaluation of the Pollutant
       Emissions from Gas-Fired Forced Air  Furnaces,"  AGA Laboratories
       Research Report No. 1503,  Cleveland, OH,  May 1975.

5-2.   Himmel, R. L. and D. W.  De Werth, "Evaluation of the Pollutant
       Emissions from Gas-Fired Ranges," AGA Laboratories Research  Report
       No. 1492, Cleveland, OH, September 1974.

5-3.   "NOX Emissions of Seven  Furnaces Predominant in the California Area,"
       Report by AGA to GAMA in response to the  proposed CARB Model  Rule,
       Arlington, VA, August 1978.

5-4.   Grandy, D. M. and T. Beutenmuller, "Proposed Model  Rule for  the Control
       of Oxides of Nitrogen Emissions from New  Gas-Fired Fan Type  Central
       Furnaces," State of California Air Resources Board,  Sacramento, CA,
       March 1978.

5-5.   Personal communication with Douglas  Grandy,  California Air Resources
       Board, Sacramento, CA, August 16, 1979.

5-6.   Martin, G. B., "Evaluation of a Prototype Surface Combustion  Furnace,"
       in the Proceedings of the  Second Stationary Source Combustion
       Symposium, Volume III, EPA-6QO/7-77-073c,  NTIS-PB 271  757, July 1977.

5-7.   Putnam, A. A., et a!., "Survey of Available  Technology for Improvement
       of Gas-Fired Residential Heating Equipment," Battelle  Columbus
       Laboratories Final Report  for Brookhaven  National  Laboratories,
       BNL51067, Upton, New York, August 1979.

5-8.   Personal communication with Bob L. Himmel,  American  Gas  Association
       Laboratories, Cleveland, Ohio, May 27,  1980.

5-9.   De Werth, D. W., et al., "Guidelines for  Adjustment  of Atmospheric Gas
       Burners for Residential and Commercial  Space Heating and Water
       Heating," EPA-600/8-79-005, NTIS-PB  290 777, February  1979.

5-10.  Locklin, D. W., et aj^,  "Guidelines  for Adjustment of  Residential Gas
       Burners for Low Emission and Good Efficiency,"  in the  Proceedings  of
       the Third Stationary Source Combustion  Symposium,  Volume I,
       EPA-600/7-79-050a, NTIS-PB 292 539,  February 1979.	

5-11.  Personal communication with Chuck Mueller,  Amana Inc.,  Amana, 10,
       April 14, 1979.

5-12.  Hall, R. E., et al.. "Study of Air Pollutant Emissions from  Residential
       Heating Systems," EPA-650/2-74-003,  NTIS-PB  229 697, January 1974.
                                    5-52

-------
5-13.  Katzman, L., and D. Weitzman, "A Study to Evaluate the Effect of
       Reducing Firing Rates on Residential Oil Burner Installations," Walden
       Research Report for the U.S. DOE under Contract No. 6-35738, Walden
       Corp., Wilmington, Mass., January 1976.

5-14.  Hall, R. E., "Status of EPA's Residential Space Heating Research
       Program — 1976," ASME Publication 76-WA/Fu-4, August 1976.

5-15.  Cato, G. A., et al., "Field Testing:  Application of Combustion
       Modifications to Control Pollutant Emissions from Industrial Boilers --
       Phase I," EPA-600/2-74-078a, NTIS-PB 238 920/AS, October 1974.

5-16.  Cato, G. A., et al., "Field Testing:  Application of Combustion
       ModificationsToTontrol Pollutant Emissions from Industrial Boilers —
       Phase II," EPA-600/2-76-086a, NTIS-PB 253 500/AS, April 1976.

5-17.  Carter, W. A., et al., "Emission Reduction on Two Industrial Boilers
       with Major CombustTon Modifications," EPA 600/7-78-099a, NTIS-PB 283
       109, June 1978.

5-18.  Heap, M. P., et al., "Reduction of Nitrogen Oxide Emissions from Field
       Operating Pacl
-------
5-26.  Combs, L.  P., and A.  S. Okuda,  "Design Criteria for Reducing Pollutant
       Emissions  and Fuel Consumption  by Residential Oil-Fired Combustors,"
       Paper 76-WA/Fu-10, Presented at the 97th ASME Winter Annual Meeting,
       New York,  NY, 1976.

5-27.  Combs, L.  P., and A.  S. Okuda,  "Residential Oil Furnace System
       Optimization -- Phase I," EPA-600/2-76-038, NTIS-PB 250 878, February
       1976.

5-28.  Combs, L.  P., and A.  S. Okuda,  "Residential Oil Furance System
       Optimization — Phase II," EPA-600/2-77-028, NTIS-PB 264 202, January
       1977.

5-29.  Okuda, A.  S., and L.  P. Combs,  "Field Verification of Low-Emission
       Integrated Residential Furnaces," in The Proceedings of the Third
       Stationary Source Combustion Symposium,  Volume I, EPA-600/7-79-050a,
       NTIS-PB 292 539, February 1979.

5-30.  "The Blueray System," Fueloil & Oil Heat, Vol. 36, No. J5, pp 42-44, May
       1977.

5-31.  Higginbotham, E. B.,  ^t ^1_., "Combustion Modification Controls for
       Residential and Commercial Heating Systems:  Volume II.  Oil-fired
       Residential Furnace Field Tests," EPA-600/7-81-123b, July 1981.

5-32.  M.A.N. sales brochure -- translated.

5-33.  Personal communication with R.  E. Hall,  Industrial Environmental
       Research Laboratory,  EPA, Research Triangle Park, NC, June 13, 1979.

5-34.  Hayden, A. C. S., et  al., "Emissions and Energy Conservation in
       Residential Oil Heating," Air Pollution  Control Assocation, Vol. ^8,
       No. 7_, pp. 669-672,  July 1978.

5-35.  Bonne, U., ejt aK_, "Effect of Reducing Excess Firing Rate on Seasonal
       Efficiency of 26 Boston Oil-Fired Heating Systems," Conference on
       Efficiency of HVAC Equipment and Components II, Purdue University,
       Indiana, April 12-15, 1975.

5-36.  Bonne, U., et^ £]_._, "Analysis of New England Oil Burner Data.  Effect of
       Reducing Excess Firing Rate on  Seasonal  Efficiency," Honeywell Final
       Report to the National Bureau of Standards, U.S. Department of
       Commerce,  Washington, D.C., August 1975.

5-37.  Janssen, J. E., £t &]_._, "Study of a Thermal Aerosol Oil Burner," EPA
       600/7-77-108, NTIS-PB 277 438,  September 1977.
5-38.
Katzman L., and J. P. Monat,  "Field Study of Energy Efficiency
Improvements on Residential Oil Heating Installations," Paper
No.  78-49-5, presented at the 71st Annual APCA Meeting, Houston, Texas,
June 1978.
                                    5-54

-------
5-39.  Locklin, D. W.  and R. E. Barrett, "Guidelines for Residential
       Oil-Burner Adjustments," EPA 600/2-75-069a, NTIS-PB 248 292,
       October  1975.

5-40.  Locklin, D. W.  and R. E. Barrett, "Guidelines for Burner Adjustment of
       Commercial Oil-Fired Boilers," EPA  600/2-76-088, NTIS-PB 251 919, March
       1976.

5-41.  Personal communication with Allen Okuda, Rockwell International,
       Los Angeles, California, March 26,  1979.

5-42.  Personal communication with R. Lippiatt, Blueray System Inc., New York,
       NY, March 12,  1979.

5-43.  Personal communication with Karl Klatt, M.A.N. Representative Karlson
       Blueburner Systems Ltd., Abbotsford, British Columbia, Canada, March
       12, 1979.

5-44.  Personal communication with A.C.S.  Hayden, Canadian Department of
       Energy, Ottawa, Canada, August 31,  1979.

5-45.  Giammar, R. D., et al., "Emissions  From Residential and Small
       Commercial Stoker-Coal-Fired Boilers Under Smokeless Operation,"
       EPA-600/7-76-029, NTIS-PB 263 891,  October 1976.

5-46.  Field, A. A.,  "European Trends in Space Heating," Heating,  Piping, Air
       Conditioning,  Vol. 46, No. 3, pp. 75-80, March 1973"

5-47.  Engdahl, R. B., "Cross-Feed Combustion for Clean Burning of Solid Fuels
       for Residences," Presented at the 71st Annual  Meeting of the Air
       Pollution Control Association, Houston, Texas, June 1978.

5-48.  Personal communication, with John Milliken, Industrial Environmental
       Research Laboratory, EPA, June 15,  1979.

5-49.  Brookman, G. T., and W. Kalika, "Measuring the Environmental Impact of
       Domestic Gas-Fired Heating Systems, in the Proceedings of  the 67th
       Annual Meeting, Air Pollution Control Association, June 1974.

5-50.  "Compilation of Air Pollution Emission Factors," U.S.  Environmental
       Protection Agency, Office of Air Quality Planning and Standards,
       Publication AP-42, NTIS-PB 275 525, April 1973 and supplements and
       No. 3 NTIS-PB  235 736, July 1974, and No. 6, NTIS-PB 254 274, April
       1976.

5-51.  Statistical Abstract of the United States -- 1978, U.S. Department of
       Commerce, 99th Annual Edition, Section 15, Pg. 480-485, September 1978.

5-52.  Dickerson, R.  A., and A.  S.  Okuda,  "Pollutant Formation and Emission
       from No. 2 Distillate Oil Combustion," presented at the 66th Annual
       AIChE Meeting, Philadelphia, Pennsylvania, November 1973.
                                    5-55

-------
                                 SECTION 6
                         ENVIRONMENTAL ASSESSMENT

       The majority of residential and commercial heating systems burn
natural gas and fuel oil; thus the primary environmental impact of these
sources is on ambient air quality.  Solid waste streams come from
residential and commercial wood- or coal-fired equipment, but these units
constitute a very small portion of the total number of existing
residential and commercial heating equipment.  This may change, however,
due to the recent increase in wood burning equipment throughout the U.S.
Although, residential warm air furnaces and commercial hot water or steam
boilers contributed each approximately 2.0 percent of the total manmade
NO  emissions in 1977, their impact on ambient NO  levels in urban
  X                                              X
areas  is more significant than these percentages indicate
(Reference 6-1).  The seasonal usage pattern, the low stack heights and
spatial density are the principal factors which contribute to a
disproportionate impact of residential and commercial heating systems on
ground level ambient N0? concentration during the cold winter season.
The main focus of this section will be on assessing the environmental
impact of NO  emissions control for residential and commercial heating
            /\
systems on ambient air pollutant levels.
       The environmental assessment begins with a discussion of results
from a recent field test to quantify multimedia emissions from a Blueray
low-NO  high-efficiency residential warm air furnace.  This furnace  is
      /\
considered best available NOX control technology for domestic oil-fired
control warm air furnaces.  The assessment then discusses ambient air
impacts of the other NO  controls identified in Section 5.  The
operational, maintenance, and cost impacts of these controls are then
summarized followed by an evaluation of data base and future needs.
                                    6-1

-------
6.1    ENVIRONMENTAL IMPACT ANALYSIS
       Table 6-1 sunroarizes level 1 analysis results of exhaust emissions
from a Blueray low-NO  high- efficiency home furnace in the field.  This
                     /\
furnace was recently tested as a part of the NO  EA program to quantify
                                               ^
the environmental impact of low-NO  residential systems
                                  n
(Reference 6-2).  Table 6-1 also summarizes air pollutants from five
conventional (uncontrolled) oil-fired residential warm air furnaces and
two oil-fired hot water heaters tested in another EPA sponsored test
program (Reference 6-3).  As indicated, for the Blueray unit two furnace
operating conditions were investigated; continuous operation and a
10-minutes on/10-minutes off cyclic operation.   Tests performed on the
conventional oil-fired units were mostly with 50-minutes on/10-minutes off
cycles.  However, two oil-fired systems were also tested with a 10-minute
on/20-minute off cycle to study the effect of cycle mode on organic
emissions.
       Although emissions for any one pollutant vary significantly between
test programs and test conditions, several trends are evident from the
data in Table 6-1.  For example, for the Blueray furnace CO, HC and organic
emissions (POM) increased when the furnace operation cycled.  The
contribution of combustible emissions during ignition and shutoff periods
is clearly evident here.  The average NO  emissions decreased in the
                                        A
cyclic operating mode primarily due to lower combustor temperatures.
Trace elements and particulate emissions generally remained unchanged when
the furnace was switched to cyclic operation.  However, emissions of Fe,
Ni, and possibly Cr, Mn, and Mo were noticeably higher for continuous
furnace operations.  The higher concentrations of these trace elements
during continuous firing may be partly attributed to deterioration of iron
and steel surfaces internal to the furnace and partly to contamination of
samples during sampling and analysis.  Sulfur oxides (SOp and SO.,)
emissions from the Blueray furnace are questionable because a sulfur
balance analysis indicated only 30 to 40 percent conversion of fuel sulfur
to oxides.
       For conventional furnaces, total organic emissions were about
20 percent higher than those from the Blueray unit operating
intermittently.  In addition, particulate emissions were higher for the
                                    6-2

-------
TABLE 6-1.   CRITERIA  TRACE  ELEMENTS  AND  ORGANIC EMISSIONS  FROM
               CONVENTIONAL AND LOW-NOX OIL-FIRED HEATERS
Conventional


Pollutant
Part
SO?
S03
NOX
CO
Smoke
HC
Organic
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Potassium
Selenium
Tellurium
Thalli urn
Tin
Titanium
Vanadium
Zinc
Emissions
Cyclic
Heaters3
Test Method
and
Measurement Operation,
ng/Jb Techniques
3.1
—
5.9
—
--
1.0
—
9.2
0.25
0.0057
0.0015
0.016

—
—
0.011
0.45
0.029
--
0.16
0.14
0.042
0.21
—
0.0012
—
0.29
0.23
—
—
—
	
	
0.0029
0.11
SSMS
ND
CC
ND
ND
—
ND
GC/MS
SSMS
SSMS, AAS
SSMS, AAS
SSMS
ND
ND
ND
SSMS
SSMS
SSMS
ND
SSMS
SSMS
SSMS
SSMS
ND
AAS
ND
SSMS
SSMS
ND
ND
ND
ND
ND
SSMS
SSMS
Blueray Low-N0x Furnace
Emissions
Emissions --
Continuous Cyclic
Operation
ng/Jb
0.87-1.32
26.9
0.2
10
9
—
0
0.38
—
< 0.0005
< 0.0006
< 0.011
<1.54 x
< 0.0008
< 0.0039
< 0.0022
--
< 0.1 104
< 0.0088
0.0191
0.542
< 0.027
—
< 0.0152
<0.0054
< 0.0144
< 0.0882
—
<0.0030
< 0.0009
< 0.0482
< 0.0009
< 0.0033
0.0008
0.0042
, Operation,
ng/Jb
0.82-1.30
35.5
1.0
7
59
—
5
7.63
—
< 0.0006
< 0.0007
< 0.0147
106 <1.79 x 105
< 0.0008
< 0.0130
< 0.0014
—
< 0.0072
< 0.0074
0.0149
0.0594
< 0.0278
—
< 0.0033
< 0.0039
< 0.0046
< 0.0139
—
<0.0023
< 0.0010
<0.0533
< 0.0012
<0.0013
< 0.0014
0.0037
Test method
and
Measurement
Techniques
SASS -- Method 5
EPA Method 8
EPA Method 8
Chemi luminescent
NDIR
ND
FID
GC
ND
AAS
AAS
AAS
ND
AAS
Colorimetric
AAS
ND
AAS
AAS
AAS
AAS
AAS
ND
AAS
ND
MS
AAS
ND
AAS
AAS
AAS
AAS
AAS
AAS
AAS
Average of five warm air  furnaces and  two hot water heaters
 all using conventional  high pressure burners
bng/J on a heat input basis

SASS  =  Source Assessment Stack Sampler  modified
CC    =  Controlled Condensation, a Goksoyr-Ross procedure
SSMS  =  Spark Source Mass Spectroscopy
GC/MS =  Gas Chromatography/Mass Spectroscopy
ND    -  Not determined
AAS   =  Atomic Absorption Spectrometry
NDIR  =  Nondispersive Infrared Analyzer  (continuous monitoring)
FID   *  Flame lonization  Detector (continuous monitoring)
                                    6-3

-------
conventional units.   These observations substantiate that the low-NO
                                                                    A
unit is also a high-efficiency unit.
       Trace element emissions between the two test  programs  showed few
significant differences.   These results indicate that trace element
emissions are not generally increased when using the Blueray furnace
compared to conventional  heating equipment.
       Trace element measurements were performed primarily using the Spark
Source Mass Spectroscopy (SSMS) for the conventional heaters, while Atomic
Absorption Spectrometry (AAS) was predominantly used for the Blueray
furnace.  Because of the low level of mineral  matter in the distillate
fuel oil and the small  amount of particulate matter  collected,  several
trace elements were present below detectable levels  (indicated  by the "<"
sign) when using the AAS analytical method during the Blueray tests.  SSMS
analysis of mineral  matter in the distillate fuel oil burned in the
conventional heaters indicated that for over 50 percent of the elements,
stack emissions were below 70 percent of levels entering the heaters.
This finding may indicate some retention of fuel oil mineral  matter in
residential heating equipment.
6.2    SOURCE ANALYSIS MODEL EVALUATION
       To help quantify the environmental impact of  a low-NO
                                                            A
residential furnace a Source Analysis Model, SAM IA  (Reference  6-4), was
applied to the flue gas data from the fifth Blueray  unit tested in the
NO  EA program.  IERL and the conventional units tested by GCA  have been
  /\
developing a series of Source Analysis Models to compare emission data to
environmental objectives, termed Multimedia Environmental Goals (MEGs)
(Reference 6-5).  The model selected for the level of detail  obtained from
the Blueray tests was SAM IA, designed for rapid screening purposes.  As
such, it includes no treatment of pollutant transport or formation.  Goal
comparisons employ threshold effluent stream concentration goals, termed
Discharge Multimedia Environmental Goals (DMEGs).
       For the purposes of screening pollutant emissons data to identify
species requiring further study, a Discharge Severity (DS) is defined as
follows:
          n<-  _ Concentration of Pollutant i in Effluent Stream
            i                 DMEG of Pollutant i
                                    6-4

-------
       The DMEG value, the threshold effluent concentration, is the
maximum pollutant concentration considered safe for occupational
exposure.  When DS exceeds unity, more refined chemical analysis may be
required to quantify specific compounds present.
       To compare waste stream potential hazards, a Weighted Discharge
Severity (WDS) is defined as follows:
                    WDS = (^ DS^ x Mass Flow Rate,
where the Discharge Severity is summed over all species analyzed.  The WDS
is an indicator of output of hazardous pollutants and can be used to rank
the needs for controls for waste streams.  It can also be used as a
preliminary measure of how well a pollutant control, say a combustion
modification NO  control, reduces the overall environmental hazard of
               A
the source.  An extensive exposition of SAM IA and  list of DMEGs are
presented in Reference 6-4 and will not be repeated here.
       SAM IA was used to evaluate the emissions data in Table 6-1.  Since
the model requires effluent concentrations on a mass per volume basis,  the
emission factors in Table 6-1 were converted to concentrations at a
furnace discharge vent assuming a flue gas dilutive to 17 percent 0,,.
This Op level was the average roof vent level reported in Reference 6-3.
Table 6-2 lists discharge severities for those species with DS greater
than 0.1.  In calculating DS for NO , S09, and CO for the conventional
                                   A    £_
furnace emission factors taken from AP-42 (Reference 6-5) were used, since
field tests reported in Reference 6-3 did not measure these pollutants.
       The data in Table 6-2 led to several conclusions.  First, DS values
for trace elements between the units are quite comparable as expected
based on trace elements emission results presented  in Table 6-1.  Of the
trace elements Cr and Ni emissions present the greatest potential hazard
in all cases.  However, measured levels of these metals may be an artifact
of the stream sampling methodology.  The flue gas sampling trains in both
the conventional furnace test program and the NO  EA contained many
                                                A
stainless steel components.  Thus, some of the reported Cr and Ni could
have come from the sampling train  itself rather than being a significant
component of the flue gas.
       For both types of units S02 emissions were flagged and emissions
of certain organic categories had DS values greater than 1.  For the
                                    6-5

-------
   TABLE 6-2.  FLUE GAS DISCHARGE SEVERITIES GREATER THAN 0.1 FOR THE
               BLUERAY FURNACE AND CONVENTIONAL OIL-FIRED HEATERS
Pollutant
NOX
S02
so3
CO
Arsenic (As)
Cadmium (Cd)
Chromium (Cr)
Cobalt (Co)
Copper (Cu)
Iron (Fe)
Lead (Pb)
Nickel (Ni)
Thallium (Tl)
Amines
Carboxylic acid
Total Stream DS
Blueray Furnace Conventional Furnace
(Reference 6-2) (Reference 6-3)
Continuous
Operation
0.86
1.6
0.15
0.17
0.23
0.17
85
0.14
0.075
0.42
0.14
4.5
0.37
NFC
0.20
95.7
Cyclic
Operation
0.60
2.1
0.77
1.1
0.27
0.11
5.5
0.11
0.055
0.046
0.14
0.73
0.41
NFC
2.3
15.5
Cylic Operation
4.73
6.3a
4.5
0.30a
0.60
0.85
22
NDb
0.60
0.011
0.21
15
NDb
1.6
—
59.0
aPollutant not measured in test program, DS calculated from AP-42
 emission factors:  NOX; 55 ng/J; S02J 100 ng/J; CO; 15 ng/J
^ND:   Species not analyzed for
CNF:   None found
                                  6-6

-------
conventional units amines were flagged as being of potential concern;  for
the Blueray unit carboxylic acids would be of potential concern under
cyclic operation.  The DS for NO  exceeds 1 for conventional units,  but
                                /\
is less than 1 for the low-NO  Blueray unit under both continuous and
                             A
cyclic operations.
       In sunrnary, flue gas stream Total Discharge Severity (TDS) for
typical conventional units appears to fall between the TDS for the
low-NO  unit under cyclic (normal) operation and that for the low-NO
      X                                                             X
unit under continuous operation.  If Cr and Ni are removed from the  TDS
calculations, adjusted TDSs of  22, 6.2, and  9.3  result for the
conventional, Blueray continuous, and Blueray cyclic data respectively.
Thus, if measured Cr and Ni indeed comes from the sampling train, then the
low-NO  unit's TDS under both cyclic and continuous operation is lower
      A
than that of the conventional units.  This suggests that using the Blueray
design
sound.
design to control NO  from oil-fired heating units is  environmentally
                    A
       Of the flue gas species, S0? had the largest DS value.   Its
potential hazard was  lower for the low-NO  unit than for the
                                         A
conventional units (based on an AP-42 emission factor for conventional
units), however, this is most  likely due to poor sulfur emissions test
results for the Blueray unit and fuel composition changes, rather than  a
consequence of low-NO  design.  SO, emissions were also flagged as of
                      X            o
concern for the conventional units.  The fuel sulfur to SO., conversion
for two conventional  domestic heaters was reported to range between 2.1
and 6.5 percent (Reference 6-3).  This relatively high conversion rate  for
distillate oil combustion was attributed to high combustion excess air
levels (Reference 6-3).  The DS for S03 is lower for the low-NOx unit
(again, probably uncertain due to Blueray test results as well as fuel
composition effects).
       The DS for NO  was significantly lower for the Blueray furnace,
                    A
decreasing from a value of about five for conventional units (representing
potential environmental hazard), to less than one for the low-NO  unit.
                                                                A
       Finally, the flue gas stream total DS for the low-NO  unit under
                                                           A
cyclic (or "normal")  operation was lower than that for conventional units,
                                    6-7

-------
due in part to significant NO  reductions.   However,  the Blueray furnace
                             A
DS under continuous operation was higher,  due largely to significantly
increased Cr emissions.
6.3    ENVIRONMENTAL IMPACTS OF NO  CONTROLS ON CRITERIA POLLUTANTS
                                  A
       With the exception of radiant screens and secondary air baffles for
natural gas-fired residential burners the NO  control techniques for
                                            A
either gas-fired or oil-fired residential  heaters have essentially no
adverse impact on other criteria and total  organic pollutants.  On the
contrary, some of the low-NO  high-efficiency combustor designs such as
                            A
the Blueray and the M.A.N. burners, assure low combustible emissions by
recirculating the combustion products.  The flue gas  recirculation of the
Blueray combustor results in very low CO,  UHC and smoke emissions even at
relatively low excess air operation.  The low excess  air also improves
thermal efficiency and reduces seasonal fuel consumption.  Other effective
NO  controls such as the EPA/Rocketdyne furnace, the M.A.N. burner for
  A
fuel oil and the Amana HTM for natural gas are also effective in reducing
combustible emissions while significantly lowering NO
                                                     A
       Table 6-3 summarizes the level of NO  control  achievable with
                                           A
most effective control alternatives for both gas- and distillate oil-fired
residential heaters.  Control alternatives which are  far from
commercialization have not been included.   The data indicate that the
flame retention burner head, for example,  could be used to achieve a NO
standard for distillate oil-fired warm air furnaces of 40 ng/J heat input
or approximately 50 ng/J of useful heat.  For more stringent NO
                                                               A
standards for oil-fired heaters the EPA/Rocketdyne burner head and the
Blueray design can achieve 35 and 15 ng/J on a heat input basis (11.5 and
4.9 lb/1000 gal of oil) respectively.  For natural gas-fired heaters the
modulating furnace and the Amana HTM combustor could achieve NO
standards of 25 and 10 ng/J on a heat input basis (920 and 390 ng/m3 of
gas) respectively.
       With the exception of the South Coast Air Quality Management
District (SCAQMD) in Southern California,  there are no promulgated
regulations governing NO  emissions from residential  heaters.  Rule 1111
                        A
of the SCAQMD states that all natural gas-fired residential warm air
furnaces for stationary residences sold after January 1, 1984, must not
                                    6-8

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TABLE  6-3.   ENVIRONMENTAL  IMPACT OF  MOST EFFECTIVE  NOX  CONTROL
               ALTERNATIVES ON  RESIDENTIAL  SPACE HEATERS
Emission Level
ng/J Heat
Input
40b
35
19
15
25
10
ng/J Heat
Output or
Useful Heat
50
45
29
20
35
12

Fuel
Distillate oil
Distillate oil
Distillate oil
Distillate oil
Natural gas
Natural Gas
Best Control
Alternative
Flame retention
burner head
EPA/Rocketdyne
burner head
EPA/Rocketdyne
furnace
Blueray Furnace
H.A.N. Burner
Modulating furnace
Amana HTM Combustor
Environmetal
Impact3
Percent Change
in Emissions
CO UHC Smoke
-47 -78 -38
-57 -80 -78
-33 -73 -90
-80 -56 -100
N/A N/A -70
N/A N/A
N/A N/A
Application
R — Retrofit
N - New
N, R
N, R
N
N
N, R
N
N
 »Percent reductions are based on baseline NOX emissions data reported
  in Reference 6-6 and average controlled levels reported in Section 5
  of this report.
 lowest NOX level measured from a flame retention burner (Reference 6-7).
                                       6-9

-------
exceed 40 ng/J of useful  heat (the thermal  heat output of a system).
Brookman and Kalika measured uncontrolled  NO  levels  from existing gas-
                                            A
fired heaters at about 60 ng/J of heat input (Reference 6-6).   This
emission level translates to about 85 ng/J  of useful  heat for  a furnace
cycle efficiency of 70 percent.   Thus the  SCAQMD Rule 1111 requires more
than 50 percent NO  reduction from uncontrolled levels.   As indicated in
                  /\
Table 6-3,  both the modulating furnace and  the HTM combustor can meet this
regulation.   Furthermore, the commercial development  of the Bratko burner
could in the near future  add one  more control  alternative capable of
meeting stringent NO  regulations for natural  gas-fired  heaters.
                    /\
       Table 6-3 also shows the effect of  NO  controls on other criteria
                                            /\
pollutants.   As indicated, there are substantial reductions of combustible
emissions from distillate oil-fired space  heaters for each of  the NOX
control alternatives listed.  These percent reductions were calculated
using the cyclic emission levels  suggested  by Barrett ejt a!. as being
representative of existing residential oil-fired heaters (Reference 6-8).
These suggested uncontrolled combustible emissions, however, account for
equipment in need of tuning.  Therefore, tuning, maintenance and other
controls discussed in Section 5  (see Table  5-7) could also reduce these
combustible emissions lowering the percent  reductions of Table 6-3
substantially.  However,  it can be generalized that selected most
effective NO  control alternatives also reduce overall  seasonal
            J\
combustible emissions as  well  as  lowering  NO .
6.4    OPERATIONAL AND COST IMPACTS OF CONTROLS
       NO  controls listed in Table 6-3 for both natural gas and
         /\
distillate oil-fired residential  heaters not only reduce NO and
                                                           A
combustible  emissions but often bring about an improvement in  equipment
operating performance.  For example for oil-fired equipment, both the
Blueray and  the EPA/Rocketdyne furnace design have shown an improvement in
seasonal thermal efficiency of at least 10  percent above that  of
conventional warm air furnaces.   The Blueray furnace  shows no  loss in
performance  and maintains minimum smoke and combustible emissions
(Reference 6-9).  Similarly, the recently  developed EPA/Rocketdyne furnace
has demonstrated relatively steady performance over an average field test
period of 2  months (Reference 6-10).  Furthermore, representatives of the
                                    6-10

-------
M.A.N. burner claim that the thermal efficiency and overall performance of
their system does not deteriorate thus the burner does not require yearly
servicing as do conventional oil- fired residential heaters
(Reference 6-11).  However, field tests have not yet been performed to
verify these claims.
       Table 6-4 lists the cost data available for the NO  control
                                                         A
alternatives discussed throughout this report for residential heating
systems.  Since no cost data are available on the M.A.N. burner either for
a retrofit or new installation this control has not been listed.  As
indicated, retrofit of the optimized burner head for residential oil-fired
warm air furnaces represents the most cost-effective alternative to
achieve a NO  emission level of about 45 ng/J of useful heat.  The
            A
payback period for the initial investment of $43 is estimated at less than
one year.  Retrofit of the flame retention burner head to achieve NO
                                                                    A
emissions of about 50 ng/J of useful heat from existing furnaces is the
second most effective control alternative for this level of control.
Payback period is also estimated at less than one year.  For a stringent
NO  emission control level of about 20 ng/J of useful heat for new oil-
  A
fired heaters the Blueray "blue flame" furnace is the most cost-effective
as well as the only commercially available alternative.
       The payback periods  listed in Table 6-4 are estimates based on the
time required to recover the money spent for the initial investment of
installing NO  control equipment.  Since all these control alternatives
             A
bring about an increase in thermal efficiency, and thus fuel savings, the
control is often paid for with the fuel cost savings cunmulated over a
time period less than a year.  It should also be pointed out that for new
equipment installed in new homes the cost of the furnace is generally
included with that of the house.  The incremental cost of the furnace is
then annualized over the mortgage period of the house  (i.e., 20 to 30
years).  For example, the estimated $100 incremental cost of a Blueray
furnace would be annualized to about $11 per year for  a 20 year mortgage
at 9.25 percent interest.  It can be seen that the annual fuel savings,
$100 for a typical oil bill of $500/year (Reference 6-9) would more than
compensate for the $11 increase in annual mortgage rate.
                                    6-11

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                                              TABLE  6-4.    COST  IMPACT OF NOX  CONTROL  ALTERNATIVES
 I
I—•
ro
Control
Amana (HTM) Furnace
Modulating Furnace
Surface Combustion
Burner (Infrared Bratko
type)
Pulse Combustion
Burner0
Catalytic Combustion
Burner0
Flame Retention Burner
Head
Flame Retention Burner
EPA/Rocketdyne Burner
Head
EPA/Rocketdyne Furnace
Blueray Furnace
Fuel
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Distillate Oil
Distillate Oil
Distillate Oil
Distillate Oil
Distillate Oil
Achievable NOX Level
ng/J Useful Heat
12,
(390 ng/m3gas)
35
(920 ng/m3 gas)
12
(39 ng/mj gas)
21
(683 ng/m3 gas)
Estimated
(163 ng/m3 gas)
50
(1.8 g/kg fuel)
50
(1.8 g/kg fuel)
45
(1.6 g/kg fuel)
29
(0.9 g/kg/fuel)
20
(0.7 g/kg fuel)
1978
Incremental
Investment Cost
$100-$300 over cost
of conventional furnace
$50-$250 over cost
of conventional furnace
$100- $200 over cost of
conventional furnace/
heater
$300-$600 over cost of
conventional furnace/
heater
$150-$250 over cost of
conventional furnace/
heater
152 - retrofit
including installation
$385 — retrofit of
reduced capacity burner
$43 — retrofit
including installation
$250 over cost of
conventional furnace
$100 over cost of
conventional furnace
Cost Effectiveness
$/(ng/J)a
1.7-5.2
1.4-7.0
1.7-3.4
6.1-12.2
2.3-3.9
2.6
12.8
1.3
4.2
1.7
Payback Period
Based on Annual
Fuel Bill of $500
1-3 years
1-3.8 years
3.5-8.0 years
1.7-3.5 years
1.4-2.3 years
Less than 1 year
3.5 years
Less than 1 year
2.5 years
1 year
                    aBased on uncontrolled NOX emissions  of 70 ng/J heat output  for natural gas-fired heaters  and 80 ng/J heat output
                     for distillate oil-fired heaters. Cost-effectiveness is based on the differential investment cost of the control.
                    °Based on Installation on a condensing system where seasonal efficiencies can be as high as 95 percent.

-------
6.5    DATA BASE EVALUATION AND NEEDS
       The review of published papers on residential  and commercial
heating systems conducted in this study has revealed  a substantial  amount
of criteria emissions data for gas- and oil-fired residential  heaters.
Recently, noncriteria pollutants (trace elements and  organics)  have  also
been measured.  Residential equipment has been extensively characterized
and inventories are well documented.  In addition, few control
alternatives for NO  and combustible pollutants have  also been
                   /\
investigated.  Some low-NO  and high-efficiency furnace designs are
                          A
commercially available, while other equally or more effective  designs are
either in final demonstration stages or await commercialization.
Performance data on these improved heating equipment  designs are being
gathered through EPA sponsored field and laboratory programs.   These and
other test programs will aid  in further documenting the performance,
reliability of these advanced sources and quantifying their impact  on
other pollutant emissions.
       This general availability of emissions and NO   control  technology
                                                    n
data for residential warm air furnaces is contrasted  by the purity  of
inventory and emission test data for commercial space heating  equipment
with heat input generally less than 0.3 MW (106 Btu/hr).
       These units include rooftop commercial heating equipment,  both
indirect and direct fired, which are often combined with air conditioning
systems, and a number of indoor waters.  The impact of these sources needs
to be identified through a detailed inventory of existing equipment  and  a
review of use patterns and fuel consumptions.
       These commercial space heating sources could be substantial
contributors to ambient N0? concentrations during the cold season.   With
the exception of the EPA/Rocketdyne low-NO  burner head design for
                                          J\
commercial size oil-fired burners little NO  control  technology has  been
                                           A
developed.  Although combustion equipment in this source category is
generally similar to the residential equipment, the assumption that low
NO  burner systems may be applicable to commercial units is only
  A
speculative at present.  Other low NO  design concepts such as flue gas
                                     A
recirculation as used in the Blueray furnace and M.A.N. burners can
probably be scaled up to commercial size equipment.  In fact,  the M.A.N.
                                    6-13

-------
burner is being scaled  up to  0.45  MW  (1.5  x 106 Btu/hr).   A unit is
being tested in W.  Germany (Reference 6-11).
       Information  on  NO   control  alternatives  for commercial  size steam
                        A
and hot water boilers  burning gas  or  oil  is also scarse.   While it can be
speculated that some boiler designs  lend  themselves to  N0x control
techniques investigated for industrial  size boilers,  little experimental
data exist to confirm  this.  Furthermore,  low-NOx burner  technology for
heat input capacities  in the  size  range of 0.1  to 2.9 W  (0.4  to 10 x
10  Btu/hr) show promise  based on  advanced burner technology developed
for both residential units on the  small side and industrial units  on the
large side.  For example, the TRW  oil-fired low-NOx burner
(Reference 6-12) with  a capability of reducing  NO  up to  50 percent
                                                 /\
while increasing fuel  efficiency is  being demonstrated  on industrial size
boilers.  However,  the low-NO  design concept of this burner can
                                                                  f\
apparently be scaled down to  capacities less than 2.93  MW (10  x 10  Btu/hr),
Lack of regulatory incentives for  commercial  size boilers has  suppressed
efforts in this area however.
       In the area  of  solid fuel-fired  residential and  commercial
equipment NO  technology is also very limited.   Past  and  on-going  test
            A
programs have mainly dealt with quantifying the pollutant levels and
identifying equipment  operating parameters and  fuel characteristics which
have some  impact on these levels.   Primary pollutants of  interest  for this
category of equipment  have been particulate and smoke emissions as well  as
levels of organics, toxic elements and POM.  Solid fuel  fired  equipment,
whether coal- or wood-fired,  often does not permit extensive modifications
of equipment or operating procedures  to reduce  NO  levels.  Investigative
                                                 /\
efforts in this area should continue  to determine potential NO  control
                                                              /\
technology while still  concentrating  on reducing the impact of other
criteria and noncriteria pollutant emissions.
       Cost data on NO  control alternatives for residential heating
                      ^
systems was generally  not precise.  This  prevented a detailed  economic
impact of widespread implementation  of control  alternatives.  Future EA
programs should deal in more  detail  with  cost impact of NO  control
                                                          /\
devices to achieve  specific levels of control.   However,  presently
available cost data indicate  that  the incremental cost  of NO  controls
                                    6-14

-------
to the homeowner is often small  (especially for new equipment)  and
generally reversable within a short time through savings in  fuel  oil
consumptions.
                                    6-15

-------
                          REFERENCES  FOR  SECTION 6


6-1    Waterland,  L.  R.,  et  al..  "Environmental Assessment  of  Stationary
       Source NOX  Control  Technologies  — Final Report," Acurex  Draft
       Report, EPA Contract  68-02-2160, Acurex Corporation,  Mountain View,
       CA, September  1979.

6-2.   Higginbotham,  E.  B. , "Combustion  Modification  Controls for
       Residential and Commercial  Heating Systems:   Volume  II.   Oil-fired
       Residential Furnace Field  Tests  "  EPA-600/7-81-123b,  July 1981.

6-3.   Surprenant, N. F.,  et al..  "Emission Assessment of Conventional
       Stationary Combustion Systems: Volume 1.  Gas-  and Oil-Fired
       Residential Heating Sources",  EPA-600/7-79-029b,  NTIS-PB  298-494,
       May 1979.

6-4.   Shalit, L.  M., and K.J. Wolfe, "SAM/IA: A Rapid Screening Method
       for Environmental Assessment of  Fossil Energy Process Effluents",
       EPA-600/7-78-015, NTIS-PB177 088/AS, February 1978.

6-5.   "Compilation of Air Pollutant Emission Factors, Third Edition,
       Including  Supplements 1-7", EPA  Publication AP-42,  NTIS PB 275-525,
       October 1977.

6-6.   Brookman,  6. T. and Kalika, W.,  "Measuring  the Environmental Impact
       of Domestic Gas-Fired Heating Systems," in  the Proceedings of the
       67th Annual Meeting,  Air Pollution Control  Association, June 1974.

6-7.   Hall,  R. E., et _aJL,  "A Study of Air Pollutant Emissions from
       Residential Heating Systems," EPA-650/2-74-003, NTIS PB-228 667,
       January 1974.

6-8.   Barrett, R. E., £t _al_., "Field Investigation of Emissions from
       Combustion Equipment for Space Heating," EPA R2-0842 and API
       Publication 418, June  1973.

6-9.   "The  Blueray  Systems"  Sales Brochures provided by Blueray Systems, -
       Inc.,  Mineola, New York, October  1978.

6-10.  Okuda, A.  S.  and Combs, L. P., "Field Verification of Low Emission
       Integrated Residential Furnaces,"  in Proceedings of  the Thi d
       Stationary Source  Combustion  Symposium, Volume 1 EPA-600/7-78-050,
       February 1979.

6-11.  Personal communication with Karl  Klatt, M.A.N. Representative,
       Karl son, Scarborough,  Ontario, Canada, March 13, 1979.

6-12.  Personal Communications with  R. R.  Koppang, TRW Inc.,  Redondo
       Beach, CA, March 12, 1979.
                                     6-16

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                               TECHNICAL REPORT DATA
                         (Please read Instructions on the reverse before completing)
1. REPORT NO.
 EPA-600/7-81-12 3a
                           2.
                                                     3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE Combustion Modification Controls for
Residential and Commercial Heating Systems: Volume
I. Environmental Assessment
            5. REPORT DATE
            July 1981
            6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
C. Castaldini, R. A. Brown, and K. J. Lim
                                                     8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Acurex/Energy and Environmental Division
485 Clyde Avenue
Mountain View, California  94042
            10. PROGRAM ELEMENT NO.
            E HE 62 4 A
            11. CONTRACT/GRANT NO.
            68-02-2160
 12. SPONSORING AGENCY NAME AND ADDRESS
 EPA, Office of Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC  27711
            13. TYPE OF REPORT AND PERIOD COVERED
            Task Final; 6/78-9/79
            14. SPONSORING AGENCY CODE
             EPA/600/13
15. SUPPLEMENTARY NOTES JERL-RTP project officer is Joshua S.  Bowen, Mail Drop 65,
919/541-2470.
16. ABSTRACT
              repOrj- gjves an environmental assessment of combustion modification
techniques for residential and commercial heating systems , with respect to NOx con-
trol reduction effectiveness, operational impact,  thermal efficiency impact, control
costs, and effect on emissions of pollutants other than NOx.  Major equipment types
and design trends are reviewed, although emissions and control data for commercial
systems are very sparse. Natural gas and distillate oil are the principal fuels. NOx,
CO, unburned hydrocarbons, and (for oil firing) particulate are the primary pollu-
tants.  For gas-fired residential systems, high radiative  heat transfer burners have
been developed, which lower NOx emissions by about  80% without increasing emis-
sions of combustibles. For oil-fired residential systems, several new burner de-
signs, including integrated burner/furnace systems, have been developed,  which
lower NOx by 20-85% and generally decrease CO, UHC, and particulate emissions.
Commercial application of these systems is  very limited. Since  the control tech-
niques generally increase thermal efficiency, the additional initial investment cost  -
can often be recouped in a year. Field test data of a commercial, oil-fired, low-
NOx residential system indicate that the system poses less of an environmental
hazard than older conventional systems .
17.
                             KEY WORDS AND DOCUMENT ANALYSIS
a.               DESCRIPTORS
Pollution
Heating
Combustion Control
Nitrogen Oxides
Natural Gas
Fuel Oil
Assessments	
18. DISTRIBUTION STATEMENT
                                          b.lDENTIFIERS/OPEN ENDED TERMS
                          COSATl Field/Group
Pollution Control
Stationary Sources
Residential Systems
Commercial Systems
Combustion Modification
Environmental Assess-
  ment
13 B
13H
21B
07B
21D

14B
 Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
   189
20. SECURITY CLASS (This page)
Unclassified
                        22. PRICE
EPA Form 2220-1 (9-73)

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                                  United States
                                  Environmental Protection
                                  Agency
                                  Industrial Environmental Research
                                  Laboratory
                                  Research Triangle Park NC 27711
vVEPA
                                  Research and Development
                                  EPA-600/S7-81 -123 August 1982
Project Summary
                                  Combustion  Modification
                                  Controls for  Residential and
                                  Commercial  Heating  Systems
                                  C. Castaldini, K. J. Lim, and L. R. Waterland
                                   This report  provides an environ-
                                  mental assessment of combustion
                                  modification techniques for residential
                                  and commercial heating systems. The
                                  assessment evaluates NOX reduction
                                  effectiveness, operational impact,
                                  thermal efficiency impact, control
                                  costs, and effects on pollutant emis-
                                  sions other than NOX- Major equip-
                                  ment types and design  trends are
                                  reviewed, although emissions and
                                  control data for commercial systems
                                  are very sparse. Natural gas and
                                  distillate  oil are  the principal fuels.
                                  NOx, CO, and unburned hydrocarbons
                                  (and particulates for oil-firing) are the
                                  primary pollutants. High radiative heat
                                  transfer burners have been developed
                                  for gas-fired  residential systems,
                                  lowering  NOX emissions by about 80
                                  percent without increasing emissions
                                  of combustibles. For oil-fired resi-
                                  dential systems, several new burner
                                  designs (including integrated burner/
                                  furnace systems) have been devel-
                                  oped,  lowering  NO* by 20 to 85
                                  percent and generally decreasing CO,
                                  HC, and particulate emissions. Com-
                                  mercial application of these systems is
                                  very limited. No operational or main-
                                  tenance problems are expected. Since
                                  the  control techniques generally
                                  increase thermal efficiency, the addi-
                                  tional initial investment cost will  be
                                  offset  by operational savings.  Field
                                  test data from a commercially available
                                  oil-fired low-NOx residential system
                                  suggest that the system poses less of a
                                  potential environmental hazard than a
                                  conventional unit.
                                   This Project Summary was devel-
                                  oped by EPA's Industrial Environ-
                                  mental Research Laboratory, Research
                                  Triangle Park, NC, to announce key
                                  findings of the research project that is
                                  fully documented in a separate report
                                  of the same title (see Project Report
                                  ordering information at back).

                                  Introduction
                                   With  the increasing extent of NOX
                                  control application  in the field, and
                                  expanded INOX control development
                                  anticipated for the future,  there  is
                                  currently a need to ensure that: (1) the
                                  current and emerging control tech-
                                  niques are technically and  environ-
                                  mentally sound and  compatible  with
                                  efficient and economical operation  of
                                  systems to which they are applied, and
                                  (2) the scope and timing of new control
                                  development programs are adequate to
                                  allow stationary sources of NOX  to
                                  comply with  potential air quality
                                  standards. With these needs as back-
                                  ground, EPA's Industrial Environmental
                                  Research Laboratory, Research Triangle
                                  Park (IERL-RTP) initiated the "Environ-
                                  mental Assessment of Stationary Source
                                  NOX Combustion Modification Tech-
                                  nologies Program" (NOX EA)  in 1976.
                                  This program  has two main objectives:
                                  (1) to identify the multimedia environ-
                                  mental impact of stationary combustion
                                  sources and NOX combustibn modifica-
                                  tion controls applied to these sources,
                                  and  (2) to identify  the most cost-
                                  effective, environmentally sound NOX
                                  combustion modification controls for
                                  attaining and maintaining current and

-------
projected  NO2 air quality standards  to
the year 2000.
  The  NOX EA's assessment activities
have placed primary emphasis on:
major  stationary fuel  combustion NOX
Sources (utility boilers, industrial boilers,
gas turbines,  internal combustion
engines, and commercial and residential
heating systems); conventional gaseous,
liquid, and solid fuels burned in  these
sources; and combustion modification
control applicable to these sources with
potential for implementation to the year
2000.
  This report summarizes the environ-
mental assessment of combustion
modification controls for commercial
and residential  heating  systems. It
presents  an outline  of the environ-
mental, economic, and operational
impacts of applying combustion  modi-
fication controls to this source category.
Results of a field test program aimed at
providing  data  to support the environ-
mental and operational  impact evalua-
tion are also summarized.
Conclusions

Source Characterization
  Figure 1 shows  that commercial and
residential  sources with a  heat  input
capacity  <2.9 MW  (<107 Btu/hr)
constitute the fourth  largest  NOX
emission category, contributing nearly
7 percent  of the  total  NOX from  all
stationary sources. Major fuel combus-
tion sources in the  residential  and
commercial category are central warm
air  furnaces, room  or direct heaters,
residential  hot water  heaters, and
steam  and hot  water  hydronic  boilers
used for space or water heating. Minor
sources include stoves and  fireplaces;
these consume a relatively insignificant
quantity of fuel compared to other space
heating equipment. A breakdown of
1977 IMOx  emissions  from  residential
and commercial sources indicates that
central warm air furnaces contributed
14  percent,  steam and  hot  water
heaters 26.1  percent, and  warm air
space heaters 4.3 percent of the  total
NOX from the  sources. A  variety of
factors, including  continuing demand
for  new housing and fuel use trends,
will  tend  to increase NO*  emissions
from residential  heating systems. Thus,
given this  trend and their potential for
NOx control, residential and commercial
heating systems  represent  a priority
source category for evaluation  in the
NO, EA.
  The primary fuels used for  residential
heating are natural gas  and distillate
                       Commercial and
                     residential 2.9 MW
                    (10 x 10* Btu/hr) 6.8%

                     Incineration 0.4%

                Noncombustion 1.9%

                 Gas turbines 2.0%

            Others (fugitive) 4.1%

             Industrial process
               heaters  4.1%
 Industrial and commercial
     boilers >2.9 MW
 f>10x 10e Btu/hr) 9.7%
                                     Reciprocating
                                      1C engines
                                         18.9%
                           Total from all sources: 10.5 Tg/yr (11.6 x JO6 ton/yr)
                   Warm air space heaters 4.3%
Warm air
central
furnaces 14.0%
 Miscellaneous combustion* 17.4%
    Firetube boilers 12.5%
   Watertube boilers 1.4%
                                                       Steam and hot
                                                       water heaters
                                                       26.1%
                                       Cast iron boilers
                                       30.3 %
                           Total from all sources with capacity less than 2.9 MW
                           (WxW6 Btu/hr): 0.709 Tg/yr (0.781 x W6 tons/yr)

                           ^Includes cooling and air conditioning


Figure 1.  Distribution of stationary man-made sources of NOx
          emissions for the year 1977 (controlled NOx levels.ffieference 1).

-------
oils (No. 1 and 2 distillate). These fuels
combined account for nearly 90 percent
of all fuel burned for domestic heating.
Liquefied petroleum gas(LPG-butane or
propane), coal, and wood are also used,
although in relatively small quantities.
In 1976, LPG-fired equipment accounted
for about 6 percent of domestic heating
equipment, while coal- and wood-fired
units accounted for only  2  percent.
Built-in, residential, electric  heating
systems, including  heat  pumps, have
become increasingly  popular as
domestic supply of clean fuels dwindles
and fuel costs increase. Electric heaters
in 1 976 accounted for nearly 14 percent
of residential heating equipment.
  The  primary fuels  and  equipment
types used for  domestic heating show
significant  regional  variations. For
example, the  Northeast  depends pri-
marily  on oil-fired steam or hot water
units, while in all other regions, natural-
gas-fired central warm air furnaces are
used primarily for domestic space
heating.
  Combustion  equipment designs for
most residential  heating systems are
quite similar.  For natural-gas-fired
equipment, the single-port upshot  or
the tubular  multiport burners are the
most common.  Natural-gas-fired warm
air furnaces, room heaters, or hot water
heaters generally use a pilot flame  to
ignite  the  burner automatically.
Distillate-oil-fired residential  heating
systems  generally  use  high-pressure
atomizing gun burners. Nearly all new
oil-fired burners use theflame retention
burner  head  which  promotes more
efficient combustion.
  Commercial heating systems can  be
divided  into three general  categories:
warm air unit heaters or space heaters,
warm air furnaces or duct heaters, and
hot  water or  steam  systems.  The
combustion systems for commercial
warm air units (or space heaters) and
duct heaters are generally similar  to
residential systems, although there are
a few unique  commercial gas-fired
designs. Warm  air units and duct
heaters  are  either direct  or  indirect
fired. Direct fired heaters use only clean
gaseous fuels, exhausting the combus-
tion  products directly into  the  heated
space.  Indirect fired heaters use either
gas or oil and are vented to the outdoors.
These  units, except for their larger
capacity, are  generally  similar  to
residential central warm air furnaces.
  Hot water and steam systems in the
commercial size capacity, here defined
in the range of 0.12 - 2.9 MW[(0.4 -10)
x  106 Btu/hr]  heat  input capacity,
include cast iron hydronic boilers, and
small  firetube  and watertube boilers
used  in  both  the commercial  and
industrial  sectors.  Cast iron  hydronic
boilers are also used  in  residential
applications. These units, common  in
the Northeast and Northcentral regions
of the U.S., are primarily either gas-  or
distillate-oil-fired.  Firetube and small
watertube  boilers  used to heat  large
commercial plants  and buildings are
similar to the smaller industrial boilers
used to generate process steam. These
boilers are  generally fired with gas, oil,
or (less frequently) stoker coal,  and
account for about  25  percent of the
installed capacity  of steam  and hot
water boilers with heat input capacity
less than 2.9 MW (10 x  106 Btu/hr).

Source Emissions
  Because natural gas and distillate oil
are the principal fuels used in residential
and  commercial heating  systems,  air
pollutant emissions represent  the
primary waste stream of environmental
concern. Coal- and wood-fired furnaces
and stoves, however, also produce ash
solid waste streams. Although increas-
ing in popularity due to the scarcity and
high cost of other fuels and electricity,
residential wood- and coal-fired systems
still account  for only 2 percent of all
domestic heaters. Thus, nationally,
solid  waste streams from  residential
heating pose an insignificant environ-
mental concern. Commercial coal-fired
watertube and firetube stokers are also
the source  of  solid waste streams.
These units, which account for about 15
percent of the firetube and watertube
population,  could increase in popularity
with economic  and political  incentives
for increased use of domestic coal.
  Flue gas emissions from natural-gas-
fired residential and commercial com-
bustion sources include primarily NOX,
CO, and  unburned hydrocarbons (HC).
When fuel oil or coal is burned, smoke,
paniculate, and S02 are also emitted.
The levels of NO,, CO, and HC from oil
and coal combustion are usually higher
than those from gas combustion. Figure
2 shows the general trends  of steady-
state smoke and gaseous emissions
from  oil-fired residential  heaters as  a
function of combustion  air settings.
Commercial boilers show similar trends.
For both equipment types, the operating
setting corresponding to  lowest emis-
sions of  CO, HC, and smoke coincides
with high NOX levels. As the excessairis
reduced from  the  theoretical  setting,
concentrations of CO, HC, and smoke
increase because of lack of oxygen in
the flame and reduced turbulent mixing
which leads to incomplete combustion.
At very high excess air  levels, these
emissions can also increase due to the
excessive  combustion  air which cools
the flame, also resulting in incomplete
combustion.
  A  major factor contributing to high
combustible emissions,  particularly in
residential burners, is  the  transient
operating  mode.  The on/off  cycle is a
dominant characteristic of warm air
furnaces,  and  is quite important as a
cause of increased emissions. Figure 3
shows qualitative emission traces from
an oil burner during a typical cycle. CO
and  HC emissions peak at ignition and
shutoff.  HC concentration  drops to
insignificant levels between the peaks,
while CO emissions tend to flatten out
at a measurable level. Particulate
emissions continuously taper off after
the ignition-induced peak, whereas NO
emissions first rise rapidly for a short
period  and then continue to rise at a
more moderate rate as the combustion
chamber temperature increases. These
transient emissions are caused mainly
by variations in  combustion chamber
temperature. At ignition, a  cold re-
fractory will not  assist complete com-
bustion; therefore, peaks of CO, HC, and
smoke can occur. In addition to the cold
refractory,  wear and tear on the  oil
pump causes poor shutoff performance
and (thus) high smoke and combustible
emissions.
  In general, except for SO2 emissions
which  depend entirely  on  the sulfur
content of the  fuel, all  other criteria
pollutant  emissions are primarily a
function of burner nozzle type, combus-
tion chamber shape and  material, and
operating  practice.
  Table 1  summarizes 1977 emissions
for stationary combustion sources with
heat input less than 2.9  MW (10 x 106
Btu/hr).  These  sources include pri-
marily residential and commercial
heating  systems, as well  as small
industrial boilers.  Residential  and
commercial heating systems contribute
56 and 28 percent, respectively, of the
total  NOx from  these sources. These
emissions are seasonal;  nearly all the
total annual output occurs in the winter
months,  during  which  the  impact  of
residential and commercial heating on
ground level ambient NOa concentra-
tion in urban areas can  be significant.

-------
  2.00-
   7.50-
I
I
   1.00—

-------
  Filterable
 Paniculate
                                              NO
                                                     Burner
                                                       On
                                     Burner
                                       Off
                                                        I        -\
                     Time
                                                           Time
       HC
             Burner
               On
Burner
  Off
                             |\
                                              CO
                    Time —>•

Figure 3.   Characteristic emissions of oil burners during one
          complete cycle.
                                Time
 levels. These units are now the primary
 residential oil burners sold.
  As part  of its  combustion research
 program, EPA has supported low-NOx
 high efficiency residential burner
 development since 1971. Under one
 program,  Rocketdyne developed  a
 controlled-mixing burner  head  for
 retrofit  and new applications on
 domestic heaters. It was estimated that
 widespread application of the relatively
 inexpensive  burner head  would be
 effective  in reducing NO* by 20 percent
 and  increase efficiency by 5 percent on
 the average for each retrofitted furnace.
 Recently the burner was integrated with
 an  "optimum"*  low emission, high
•Terminology used bv Rocketdyne to characterize
the final design capable of achieving program goals
              efficiency warm air furnace. NOX
              emissions have been reduced by 65 to
              70 percent, and steady state efficiencies
              have been increased by as much as 10
              percent  over those of conventional
              designs. The  EPA program emphasized
              the necessity to match the firebox,
              burner, and heat exchanger design to
              achieve low NO* emissions while also
              maintaining low levels of CO, HC, and
              smoke.
                Both the  Blueray  "blue  flame" and
              the  M.A.N.  burners use aerodynamic
              flue gas recirculation to achieve a blue
              flame  with distillate  fuel  oil.  These
              burners thus achieve  reduced flame
              temperature,  reduced  oxygen concen-
              trations in the near-burner zone, and
              rapid vaporization of the fuel prior to
ignition. These conditions result in low
NOX emissions on the order of 1 5 to 40
ppm  corrected at zero percent excess
air, representing NOx reductions of 50 to
80 percent. Theoretically, these burners
could be scaled up to larger commercial
sizes. The Blueray furnace system is
currently the only commercially avail-
able  low NOx system in the U.S. for oil-
fired residential use. The M.A.N. burner,
developed in West Germany, is marketed
in parts of Europe and Canada.

  Techniques aimed at reducing sea-
sonal pollutant emissions from  resi-
dential heating systems  are  also ef-
fective in delivering improved fuel
economy and generally reduced equip-
ment use.  Replacement of wornout
furnaces, tuning,  and  changes  in
thermostat anticipator settings are the
most effective emission reduction tech-
niques, with overall combustible emis-
sion  reductions ranging from 1 6 to 65
percent for CO, 3 to 87 percent for HC,
59 percent for smoke, and 17 to 33 per-
cent  for particulates. Installation of de-
layed action  solenoid valves  and re-
duced  firing  capacity through  minor
modification  or installation of a new
flame retention burner are effective in
reducing excessive  smoke emissions
during  furnace start-up and shutdown.
Reported average smoke reductions
range from 24 to 82 percent. In general,
all these techniques result in fuel sav-
ings, sometimes as high as 39 percent,
in addition  to lowering  combustible
emissions.
  Application of  control  technology to
commercial heating  equipment is very
limited. Theoretically, the flame
quenching  and  surface combustion
concepts  investigated  for gas-fired
residential equipment could also apply
to commercial heaters burning natural
gas.  Similarly, low-NOx burner designs
for distillate oil firing  or optimum
air/fuel mixing concepts could possibly
be scaled  up to the larger commercial
equipment.
  NOx control technology from gas- and
oil-fired industrial boilers include low-
NOx  burners, staged combustion, flue
gas  recirculation, load  reduction,  and
low  excess air operation. These tech-
niques could possibly  apply  to com-
mercial size boilers of  similar design.
Low-NOx burners are the most attractive
control alternative for this boiler size.
Some  U.S.  companies  are  currently
working on new  burner  designs,
primarily for  oil-fired boilers. Most of
these  efforts,  however, have been

-------
Table 1. Estimated 1977 Air Pollutant Emissions from Stationary Fuel Combustion Sources with Heat Capacity Less than
2.9 MW(W x 10e Btu/hr)
r , Air Pollutant Emissions Gg (103 tons)
Fuer

Sector
Residential





Residential
and Commercial










Commercial
and Industrial






















Total


Equipment
Warm air central
furnaces


Warm air space
heaters


Miscellaneous
combustion


Steam and hot
water heaters






Cast iron
boilers






Watertube
boilers






Firetube
boilers






All equipment


Fuel
Natural gas
Distillate
oil
Natural gas
Distillate
oil
Natural gas

Distillate
oil
Natural gas

Distillate
oil
Residual oil

Coal

Natural gas

Distillate
oil
Residual oil

Coal

Natural gas

Distillate
oil
Residual oil

Coal

Natural gas

Distillate
oil
Residual
oil
Coal

All fuels

Total Capacity,
MW I106 Btu/hrj
—


—
_

	

_

	

	

	

	

143,520
1489,495)
33,730
(115,041)
53,790
(183,456)
31,590
(107,742)
5,770
119,679)
4,490
(15,313)
5,240
(17,872)
1,900
(6.480)
79,090
(269,748)
31,530
(107,538)
48.200
(164,393)
14.420
(49,181)
—

Consumption
EJ (Quads)
1.876
(1.979)
1.354
(1.428)
0.57
(0.60)
0.42
(0.44)
1.524
(1.608)
0.926
(0.977)
2.1
(2.2)
1.4
(1.5)
0.11
(0.12)
0.043
(0.045)
1.8
(1.9)
0.35
(0.37)
0.47
(0.50)
0.097
(1.0)
0.053
(0.056)
0.021
(0.023)
0.015
(0.016)
0.012
(0.013)
1.358
(1.433)
0.37
(0.39)
0.354
(0.374)
0.11
(0.116)
15.22
(16.97)

/VOx
65.7
(72.5)
33.8
(37.3)
19.9
(21.9)
10.5
(11.6)
53.3
(58.8)
27.4
(30.2)
82.8
(91.3)
77.9
(85.9)
17.5
(19.3)
7.1
(7.8)
91.7
(101.1)
23.7
(26. 1)
84.6
(93.3)
14.6
(16.1)
3.16
(3.5)
1.18
(1.3)
2.38
(2.6)
3.0
(3.3)
31.0
(34.2)
12.8
(14.1)
30.7
(33.9)
14.1
(15.6)
708.8
(781.6)

CO
19.0
(20.9)
33.8
(37.3)
5.7
(6.3)
10.5
(11.6)
15.2
(16.8)
27.4
(30.2)
17.8
(19.6)
41.7
(46.0)
1.64
(1.81)
7.53
(8.30)
35.3
(38.9)
0.56
(0.61)
0.66
(0.73)
21.3
(23.5)
1.06
11.17)
0.06
(0.07)
0.02
(0.02)
0.91
(1.00)
15.2
(16.8)
0.34
(0.38)
0.29
(0.32)
5.40
(5.95)
261.4
(288.3)

HC
6.40
(7. 10)
6.40
(7.06)
1.94
(2. 14)
1.97
(2.17)
5.20
(5.73)
5.15
(5.68)
4.76
(5.25)
13.4
(14.8)
2.74
(3.02)
2.12
(2.34)
4.06
(4.48)
3.34
(3.68)
11.8
(13.8)
5.53
(6. 10)
0.18
(0.20)
0.01
(0.01)
0.07
(0.08)
0.19
(0.21)
1.75
(1-93)
2.05
(2.26)
5.12
(5.65)
3.40
(3.75)
87.6
(96.6)


Particulates 6'CA
7.50
(8.27)
70.3
(11.4)
2.30
(2.54)
3.20
(3.53)
6.10
(6.73)
8.33
(9. 19)
16.6
(18.3)
10.6
(11.7)
9.09
(10.0)
150.2
(165.6)
6.88
(7.59)
4.18
(4.61)
13.2
(14.6)
314.3
(346.6)
0.05
(0.05)
0.18
(0.20)
0.42
(0.46)
23.5
(25.9)
3.02
(3.33)
2.57
(2.83)
5.73
(6.32)
130.0
(143.4)
728.3
(803. 1)
0.49
(0.54)
146
(161)
0.15
(0.17)
45.4
(50. 1)
0.40
(0.44)
118.4
(130.6)
0.62
0.68
150.2
(165.6)
52.6
(58.0)
30.7
(33.8)
0.53
(0.58)
37.6
(41.5)
225.6
(248.8)
110.6
(122.0)
0.02
(0.02)
3.27
(3.61)
6.70
(7.39)
16.0
(17.6)
0.23
(0.25)
18.7
(20.6)
92.1
(101.61)
91.8
(101.2)
1,148.1
(1,266.0)
 BEJ = W'a Joules = 0.948 Quads = 0.948 x W's Btu
oriented toward industrial (2.9 to 73.3
MW heat input) size boilers.

Cost of Control
  Table 4 summarizes estimated costs
for the most effective  NOX control
alternatives for  residential heating
systems. As  indicated,  retrofit  of  the
controlled mixing burner head  for
residential oil-fired warmairfurnaces is
the most cost-effective alternative to
achieve a NOX emissions level of about
45 ng/J of useful heat. Cost-effective-
ness of other alternatives for oil-fired
warm air furnaces is  generally com-
parable, falling in  the  $1 to $4 ng/J
range. Similarly, for gas-fired warm air
furnaces, both the Amana HTM furnace

-------
Table 2. Performance Summary of Low-NO* Control Equipment f
Average Cyclic Pollutant Emissions,
Operating ng/J heat input Steady State
FyrR.tn A ir Fffiripnry
Control percent /V0xa CO UHCb percent
Baseline 40-120 28-45 8.6-25 3.3-33 70
Radiant screens 40-120 15-18 6.4 NA 75


Secondary air 60-80 22 14 NA NA
baffles
Bratko Surface 10 7.5 5.5-9.6 NA NA
combustion burner
Amana (HTM/ NA 7.7 26 NA 85



Modulating NA 25 NA NA 75
furnace


Pulse NA 10-20 NA NA 95
Combustor

Catalytic NA <5 NA NA 90
Combustor
or Natural Gas-Fired Residential Heaters
1978
Cycle Installed
Efficiency, Control
percent Cost Comments
60-65 ($500-S800f
70 NA


NA NA

NA S100-$200

80 $100 -$300
over
conventional
furnace
70 S50-S250
over con-
ventional
furnace
95 S300-S600


85 $100 -$250

Costs include installation
Emissions of CO and HC can increase
significantly if screen is not placed
properly or deforms
Requires careful installation. Best
suited for single-port upshot burners
Not commercially available. Still
under development
Commercially available design. Spark
ignited, thus requires no pilot


Furnace is essentially derated. Thus
it requires longer operation to deliver
a given heat load

Currently being investigated by AGAL
Efficiencies correspond to condensing
systems.
Still at the R&D stage. Efficiencies
correspond to condensing systems.
aSum of NO + /VO2 reported as NO?
tiUnburned hydrocarbons calculated as methane
^Typical costs of uncontrolled unit
 NA  not available
Table 3.    Performance Summary of Low-NO* Control Equipment for Distillate-Oil-Fired Residential Heaters

                                  Cyclic Pollutant Emissions,

A verage
Excess A ir.
Control percent NO"
Baseline 50-85 37-85




Flame Reten- 20-40 26-88
tion Burner
Head

Controlled 10-50 34
Mixing Burner
Head by EPA/
Rocketdyne
Integrated 20-30 19
Furnace Sys-
tem by EPA/
Rocketdyne


Blueray 20 10
"blue flame"
Burner/ Furnace
System
M.A.N. 10-15 10-25
Burner



ng/ j neat input
Steady State
Smoke Efficiency,
CO UHC" Number Paniculate percent
15-30 3.0-9.0 32 7.6-30 75




11-22 0.2- J 8 2.0 NA 80-83
also depends
on heat
exchanger
13 0.7-1.0 0.5-0.9 NA 80
also depends
on heat
exchanger
20 1.2 0.32 NA 84





4.5-7.5 1.5-2.5 zero NA 84



30 NA 10 NA 85




1978
Cycle Installed
Efficiency, Control
percent Cost
65-70 ($650-
$1000f



NA $52



NA $43



74 $250 over
conven-
tional
furnace


74 $100 over
conven-
tional
furnace
NA NA




Comments
Range in NO, emissions is
for resident/a! systems not
equipped with flame retention
burners Emissions for other
pollutants are averages
If a new burner is needed as well
as a burner head, the total cost
would be $385.

Cost of mass produced burner head
only about $1 .50. Combustible
emissions are relatively low because
hot firebox was used.
Uses optimized burner head.
For new furnace installation
only. Combustible emissions are
higher than with burner head
because of quenching in an air
cooled firebox. Recent cost estimate.
New installation only.
Furnace is commercially
available. Recent cost estimate.

Both for retrofit or new
installations. Not yet
commercially available in U.S.
Commercialization expected
in 1982.
"Sum of NO and NOi reported as NO2
"Unburned hydrocarbons calculated as methane !CHt)
"Typical costs of uncontrolled unit

-------
Table 4.    Cost Impact of NO* Control Alternatives
Control

Amana (HTMI Furnace

Modulating Furnace

Surface Combustion
Burner (Infrared Bratko)

Pulse Combustion
Burner0

Catalytic Combustion
Burner"

Flame Retention
Burner Head
Flame Retention
Burner
EPA/Rocketdyne
Burner Head
EPA/Rocketdyne
Furnace
Bluer ay Furnace

Fuel

Natural Gas

Natural Gas

Natural Gas


Natural Gas


Natural Gas


Distillate Oil

Distillate Oil

Distillate Oil

Distillate Oil

Distillate Oil

Achievable /VOX Level,
ng/J useful heat
12
1390 ng/m3 fuel)

35
{920 ng/m3 fuel)
12
(390 ng/m3 fuel)

21
(683 ng/m3 fuel)

Estimated 5
(163 ng/m3 fuel)

50
(1.8 g/ kg fuel)
50
(1.8 g/kg fuel)
45
(1.6 g/kg fuel)
29
(0. 7 g/kg fuel)
20
(0.7 g/kg fuel)
1978
Incremental
Investment Cost

$100-$300 over cost of
conventional furnace
$50-$250 over cost of
conventional furnace
$100 -$200 over cost of
conventional furnace/
heater
$300-$600 over cost of
conventional furnace/
heater
$150-$250 over cost of
conventional furnace/
heater
$52— retrofit
including installation
$385— retrofit of
reduced capacity burner
$43— retrofit
including installation
$250 over cost of
conventional furnace
$100 over cost of
conventional furnace
Cost Effectiveness.
$/ng/J*

1.7-5.2

1.4-7.0

1.7-3.4


6.1-12.2


2.3-3.9


2.6

12.8

1.3

4.2

1.7

Payback Period Based
on Annual Fuel Bill
of $500, years

1-3

1-3.8

3.5-8.0


1.7-3.5


1.4-2.3


Less than 1

3.5

Less than 1

2.5

1

 a Based on uncontrolled /VOX emissions of 70 ng/J heat output for natural-gas-fired heaters and 80 ng/J heat output for distillate-oil-fired heaters.
  Cost effectiveness is based on the differential investment cost of the control.
 "Based on installation of a condensing system where seasonal efficiencies can be as high as 95 percent.
 and the modulating furnace are  com-
 parably cost-effective, in the $1 to $7
 ng/J range. Surface  combustor, pulse
 combustor, and catalytic burner for gas-
 fired units  and the Rocketdyne devel-
 oped techniques for oil-fired units are
 not commercially available.  The pay-
 back periods listed  in  the table, are
 estimates based on the time required to
 recover the money spent for the initial
 investment of installing  NOX control
 equipment. Since all  these control
 alternatives increase thermal efficiency,
 and  thus  fuel  savings,  the initial
 investment cost is often recouped in 1
 year or less.


 Incremental Emissions Due
 to Controls
   To assess the effects of a low-NOx
 burner/furnace  design on the incre-
 mental emissions of pollutant species
 other than  NOX from a residential heat-
 ing unit,  an oil-fired  Blueray low-NO*,
 high-efficiency home furnace was field
 tested. The unit  was in a  Medford, LI,
 NY, residence and had been in service
 about 1 year.  The model tested fired
 distillate fuel  oil at 0.63 mg/s (0.6
gal./hr) and had a rated  heat input of
24.6k J/s (84,000 Btu/hr). The program
involved testing in  two modes of oper-
ation: continuous  and cyclic (10 mi-
nutes on and 10 minutes off). The cyclic
mode is more representative of  typical
operation. Sampling and analysis of the
flue gas stream, using slightly modified
Environmental  Assessment Level 1
procedures, were performed (Reference
2). Detailed test results are reported in
Volume II of the full report summarized
here.
  Table  5  shows average flue gas
composition data for the  two tests.  In
the cycling test, there were peaks in the
CO and HC emissions at  the start and
end of each period of operation. This
initial peak is included in the average
concentration  noted. Start-up peak
emissions averaged 2000 ppm  for CO
and 400 ppm  for HC. The NOx levels
started at zero and, toward the  end of
the firing cycle, reached 1 6 ppm which
was the average valuefor the continuous
firing test. Average NO, emissions were
also very low  in both cyclic and con-
tinuous  operation. Paniculate  emis-
sions were very low and  did not vary
from continuous to cyclic operation.
Organic emissions increased substan-
tially for cyclic operation. Liquid column
chromatographic, infrared,  and  low
resolution mass spectrometric analyses
of the samples showed that, for both
cyclic and continuous operation, the
samples  contained primarily aliphatic
hydrocarbons, with some aromatics and
carboxylic acids.
  Table 6 summarizes flue gas emission
data,  including those for trace element

Table 5.    Flue Gas Composition:
           Blueray Unit

   Component     Cyclic    Continuous
NO*ng/J asNQt
ppm, dry
SOa, ng/J
SO3, ng/J
UHC, ng/J as CHt
ppm, dry
CO, ppm dry
COi, % dry
Oz. % dry
Paniculate, ng/J
Total OC7)
Organics, /jg/m3
6.6
11
35.5
1.0
5.0
23
160
12.9
4.0
1.30
2.63 xW
JO
16
26.9
0.2
0
0
25
13.1
3.8
1.32
1,300
                                   8

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Table 6.    Flue Gas Composition (ug/dscm).' Residential Warm air Furnaces
Element
/VOx
S02
S03
CO
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Cadmium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Tellurium
Thallium
Tin
Titanium
Vanadium
Zinc
Organics f>C7)
Bluer ay
Cyclic
5.4 x 103
2.7 x 104
770
4.5 x 104
<0.46
<0.54
<11
<0.014
<0.62
<10
<1.1
<5.5
<5.7
11
46
<21
<2.5
<3.0
<3.5

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 Table 7.     Flue Gas Discharge Severity: Oil-Fired Residential Warm Air Furnaces
                                              Discharge Severity
Component
Cr
Ni
Alkylhalides
SO2
A/OX
S03
Amines
Carboxylic acids
CO
Total stream
MEG
Category
68
76
2
53
47
53
JO
8
42

Conventional
Cyclic
22
15
13
6.3a
4.7*
4.5
1.6
—
0.30a
59.0
Blueray
Continuous
85
4.5
—
1.6
0.86
0.15
—
0.20
0.77
95.7
Blueray
Cyclic
5.5
0.73
—
2.1
0.60
0.77
—
2.3
1.1
15.5
 * Not measured; DS based on AP-42 emission factor s.
Performance  test data on  these im-
proved designs are  being gathered in
EPA sponsored field and  laboratory
programs. These and other test pro-
grams  will aid in further documenting
the performance and reliability of these
advanced controls and quantifying their
impact on other pollutant emissions.
  Cost data on NOX control alternatives
for  residential heating systems are
generally  sparse and imprecise. This
lack of definitive cost data prevented a
detailed economic impact assessment
of widespread implementation of control
alternatives.  As advanced controls
become available, future studies should
quantify the cost impact of NOxcontrol
implementation to achieve specific
levels of control.
  Information on NOX control  alter-
natives for commercial  size  steam and
hot water boilers burning gas or oil is
also scarce. While it can be speculated
that some boiler designs  lend  them-
selves  to NOx control techniques devel-
oped for  industrial  size boilers, little
experimental data exist to confirm this.
Low-NOx  burner  technology  for heat
input capacities in the size range of 0.1
to 2.9 MW (0.4 to 10 x 10s Btu/hr)
shows  promise based  on advanced
burner technology developed  for both
residential units on the small  side and
industrial  units on the larger  side, but
definitive demonstration is needed.
  NOx control  alternatives for solid-
fuel-fired  residential  and  commercial
equipment have also seen very limited
study. Past and on-going test programs
have mainly dealt with quantifying the
pollutant levels and identifying equip-
ment operating  parameters and fuel
characteristics which have some impact
on  these  levels. Primary pollutants of
interest for this category of equipment
have been  paniculate and smoke
emissions as well as levels of unburned
HC, toxic elements, and  polycyclic
organic matter (POM). The simplicity of
the solid-fuel-fired equipment, whether
coal- or wood-fired,  often does not
permit extensive modification of existing
equipment or operating procedures to
reduce NOx levels. Investigative efforts
in this area should continuetodetermine
potential NOx control technology appli-
cable to new unit design, while still
concentrating on reducing the impact of
other criteria and noncriteria pollutant
emissions.


References

1.  Waterland, L.R., et al.,  "Environ-
    mental  Assessment of Stationary
    Source  NOX Control Technologies:
    Final  Report," Acurex Draft Final
    Report  FR-80-57/EE (IERL-RTP-
    1279), EPA  Contract 68-02-2160,
    Acurex Corp., Mountain View, CA,
    April 1980.
2.  Lentzen, D.E.,  et  al., "IERL-RTP
    Procedures Manual: Level  1 Envi-
    ronmental Assessment (Second
    Edition)," EPA-600/7-78-201 (NTIS
    PB293795),  Industrial  Environ-
    mental  Research  Laboratory, Re-
    search Triangle Park, NC, October
    1978.
3.  Surpenant, N.F., et al., "Emissions
    Assessment  of  Conventional Sta-
    tionary Combustion Systems; Volume
    I: Gas-  and Oil-fired  Residential
    Heating Sources," EPA-600/7-79-
    029b (NTIS PB298494),  Industrial
    Environmental Research Laboratory,
    Research Triangle  Park,  NC May
    1979.
4.  Schalit,  L.M.,  and  K.J. Wolfe,
    "SAM/IA: A Rapid Screening Meth-
    od  for Environmental Assessment
    of Fossil Energy Process Effluents,"
    EPA-600/7-78-015 (NTIS PB277088),
    Industrial Environmental  Research
    Laboratory, Research Triangle Park,
    NC, February 1978.
                                 10

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C.  Castaldini, K. J. Urn, and L R. Water land are with Acurex Corporation,
  Mountain View, CA 94042.
J.  S. Bowen is the EPA Project Officer (see below).
The complete report consists of two volumes, entitled "Combustion Modification
  Controls for Residential and Commercial Heating Systems,"
    "Volume I. Environmental Assessment," (Order No. PB 82-231 168; Cost.
    $16.50, subject to change)
    "Volume II. Oil-Fired Residential Furnace Field Test," {Order No. PB 82-231
    176; Cost: $10.50, subject to change)
The above reports will be available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA 22161
        Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
        Industrial Environmental Research Laboratory
        U.S. Environmental Protection Agency
        Research Triangle Park, NC 27711
                                                                               11
                                                                               . 5. GOVERNMENT PRINTING OFFICE: 1982/559-092/0481

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