REPORT ON REVISIONS TO
5TH EDITION AP-42
Section 3.3
Gasoline and Diesel Industrial Engines
Prepared for:
Contract No. 68-D2-0160, Work Assignment 50
EPA Work Assignment Officer: Roy Huntley
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Prepared by:
Eastern Research Group
Post Office Box 2010
Morrisville, North Carolina 27560
September 1996
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Table of Contents
Page
1.0 INTRODUCTION 1-1
2.0 REVISIONS 2-1
2.1 General Text Changes 2-1
2.2 Emission Factors 2-1
2.3 Carbon Dioxide, C02 2-1
3.0 REFERENCES 3-1
4.0 REVISED SECTION 3.3 4-1
5.0 EMISSION FACTOR DOCUMENTATION, APRIL 1993 5-1
ii
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1.0 INTRODUCTION
This report supplements the Emission Factor (EMF) Documentation for AP-42 Section
3.3, Gasoline And Diesel Industrial Engines, dated April, 1993. The EMF describes the
source and rationale for the material in the most recent updates to the 4th Edition, while this
report provides documentation for the updates written in both Supplements A and B to the 5th
Edition.
Section 3.3 of AP-42 was reviewed by internal peer reviewers to identify technical
inadequacies and areas where state-of-the-art technological advances need to be incorporated.
Based on this review, text has been updated or modified to address any technical inadequacies
or provide clarification. Additionally, emission factors were checked for accuracy with
information in the EMF Document and new emission factors generated if recent test data were
available.
If discrepancies were found when checking the factors with the information in the EMF
Document, the appropriate reference materials were then checked. In some cases, the factors
could not be verified with the information in the EMF Document or from the reference
materials, in which case the factors were not changed.
Four sections follow this introduction. Section 2 of this report documents the revisions
and the basis for the changes. Section 3 presents the references for the changes documented in
this report. Section 4 presents the revised AP-42 Section 3.3, and Section 5 contains the EMF
documentation dated April, 1993.
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2.0 REVISIONS
2.1 General Text Changes
Information in the EMF document was used to enhance text concerning emissions and
controls. Also, at the request of the EPA, the metric units were removed.
2.2 Emission Factors
All emission factors (NOx, CO, SOx , PM-10, TOC, organic compounds, etc.) were
checked against information in the EMF Document and no changes were necessary.
2.3 Carbon Dioxide. CO.
C02 emission factors in Table 3.3-2 were originally calculated assuming 100%
conversion of fuel carbon content to C02; however; 1% of liquid fuels typically pass through
the combustion process unoxidized.(16) The C02 factors in Table 3.1-1 were modified to
reflect 99% conversion.
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3.0 REFERENCES
1. G. Marland and R. M. Rotty, Carbon Dioxide Emissions From Fossil Fuels: A
Procedure For Estimation And Results For 1951-1981, DOE/NBB-0036 TR-003, Carbon
Dioxide Research Division, Office of Energy Research, U. S. Department of Energy, Oak
Ridge, TN, 1983.
2. A. Rosland, Greenhouse Gas Emissions in Norway: Inventories and Estimation Methods,
Oslo: Ministry of Environment, 1993.
3. Sector-Specific Issues and Reporting Methodologies Supporting the General Guidelines
for the Voluntary Reporting of Greenhouse Gases under Section 1605(b) of the Energy
Policy Act of 1992 (1994) DOE/PO-0028, Volume 2 of 3, U.S. Department of Energy.
4. G. Marland and R. M. Rotty, Carbon Dioxide Emissions From Fossil Fuels: A
Procedure For Estimation And Results For 1950-1982, Tellus 36B:232-261, 1984.
5. Inventory OfU. S. Greenhouse Gas Emissions And Sinks: 1990-1991, EPA-230-R-
96-006, U. S. Environmental Protection Agency, Washington, DC, November 1995.
6. IPCC Guidelines For National Greenhouse Gas Inventories Workbook,
Intergovernmental Panel on Climate Change/Organization for Economic Cooperation and
Development, Paris, France, 1995.
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REVISED SECTION 3.3
This section contains the revised Section 3.3 of AP-42, 5th Edition.
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5.0 EMIS SION FACTOR DOCUMENTATION, APRIL 1993
This section contains the Emission Factor Documentation for Section 3.3 dated
April 1993.
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EMISSION FACTOR DOCUMENTATION FOR
AP-42 SECTION 3.3,
GASOLINE AND DIESEL INDUSTRIAL ENGINES
Prepared by:
Acurex Environmental Corporation
Research Triangle Park, NC 27709
E.H. Pechan and Associates, Inc.
Rancho Cordova, CA 95742
EPA Contract No. 68-D0-0120
Work Assignment Manager: Michael Hamlin
Prepared for:
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
April 1993
5-2
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Disclaimer
This report has been reviewed by the Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, and approved for publication. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
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TABLE OF CONTENTS
Page
LIST OF TABLES iv
CHAPTER 1. INTRODUCTION 1-1
CHAPTER 2. SOURCE DESCRIPTION 2-1
2.1 CHARACTERIZATION OF THE INDUSTRY 2-1
2.2 PROCESS DESCRIPTION 2-2
2.2.1 Fuel Type 2-2
2.2.2 Method of Ignition 2-3
2.2.3 Combustion Cycle 2-3
2.2.4 Charging Method 2-5
2.3 EMISSIONS 2-6
2.3.1 Nitrogen Oxides 2-7
2.3.2 Total Organic Compounds (Hydrocarbons) 2-9
2.3.3 Carbon Monoxide 2-10
2.3.4 Smoke, Particulate Matter, and PM-10 2-10
2.3.5 Sulfur Oxides 2-12
2.3.6 Carbon Dioxide 2-12
2.4 CONTROL TECHNOLOGIES 2-12
2.4.1 Engine Controls 2-12
2.4.1.1 Combustion Cycle 2-12
2.4.1.2 Injection Timing Retard 2-13
2.4.1.3 Preignition Chamber Combustion - "Clean Burn"
Technology 2-14
2.4.1.4 Air to Fuel Ratio 2-14
2.4.1.5 Water Injection 2-15
2.4.1.6 Derating 2-16
2.4.2 Post-Combustion Control 2-16
2.4.2.1 Selective Catalytic Reduction 2-16
2.4.2.2 Nonselective Catalytic Reduction 2-18
2.4.2.3 Diesel Particulate Traps 2-19
2.4.3 Control Technology Applications 2-19
REFERENCES 2-21
CHAPTER 3. EMISSION DATA REVIEW AND ANALYSIS PROCEDURES 3-1
3.1 LITERATURE SEARCH AND EVALUATION 3-2
REFERENCES 3-4
CHAPTER 4. EMISSION FACTOR DEVELOPMENT 4-1
4.1 CRITERIA POLLUTANTS AND CARBON DIOXIDE 4-2
4.1.1 Review of Previous Data 4-2
4.1.2 Review of New Data 4-3
4.1.3 Compilation of Baseline Emission Factors 4-3
4.1.4 Compilation of Controlled Emission Factors 4-4
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TABLE OF CONTENTS (Continued)
Page
4.2 TOTAL ORGANIC COMPOUNDS AND AIR TOXICS 4-5
4.2.1 Review of Old Data 4-5
4.2.2 Review of New Data 4-6
4.2.3 Compilation of Emission Factors 4-6
4.3 PARTICULATE 4-6
4.3.1 Review of Old Data 4-6
4.3.2 Review of New Data 4-7
4.3.3 Compilation of Emission Factors 4-7
REFERENCES 4-15
CHAPTER 5. AP-42 SECTION 3.3: GASOLINE AND DIESEL INDUSTRIAL ENGINES 5-1
APPENDIX A. SAMPLE CALCULATIONS A-l
APPENDIX B. SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE B-l
APPENDIX C. PREVIOUS MARKED-UP AP-42 SECTION C-l
LIST OF TABLES
TABLE 3-1 EVALUATION OF REFERENCES 3-3
TABLE 4-1 SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION
ENGINES: CRITERIA AND NONORGANIC GASEOUS EMISSIONS 4-8
TABLE 4-2a SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION
ENGINES: SPECIATED ORGANIC COMPOUNDS 4-10
TABLE 4-2b SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION
ENGINES: SPECIATED ORGANIC COMPOUNDS 4-11
TABLE 4-3 SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION
ENGINES: AIR TOXICS 4-13
TABLE B-l SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE B-2
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1. INTRODUCTION
An emission factor is an estimate of the rate at which a pollutant (in terms of its
mass) is released to the atmosphere divided by the level of activity from the emission
source. Section 3.3 of the "Compilation of Air Pollutant Emission Factors" (AP-42) covers
the emission factors for gasoline (up to 250 hp) and diesel (up to 600 hp) industrial engines.
The emission factors provide persons working in air pollution control with documented
estimates of source emission rates. Uses of emission factors reported in AP-42 include:
! Estimates of area-wide emissions;
! Emission estimates for a specific facility; and
! Evaluation of emissions in relation to ambient air quality.
The intent of this emission factor document is to provide background information used to
support the revision of emission factors for AP-42 Chapter 3.3 - Gasoline and Diesel
Industrial Engines.
The last update of AP-42 Chapter 3.3 was in 1975 and contained only emission
factors for carbon monoxide (CO), volatile organic compounds (VOCs) [i.e., exhaust
hydrocarbons (HC), evaporative HC, crankcase HC], nitrogen oxides (NOx), aldehydes,
sulfur oxides (SOx), and particulate matter (PM) for baseline (uncontrolled) operation.
This revision includes emission factors for those species as well as for carbon dioxide (C02)
and speciated organic compounds. The overall scope of the current revision includes the
following changes or additions:
! Review of existing criteria pollutant emission factors for uncontrolled
baseline operation using data available since the prior supplement;
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! Inclusion of several non-criteria emission species for which data are
available: organics speciation, air toxics, particle sizing, and greenhouse
gases (C02); and
! Inclusion of technical discussion and emission control factors for
engines operating with NOx, CO, VOC or diesel particulate controls.
AP-42 Chapter 3.3 deals with both types of reciprocating internal combustion
engines, namely spark and compression ignition. The chapter treats industrial-sized
compression ignition diesel engines and the industrialized spark ignition engines fired with
gasoline. Larger diesel engines are addressed in AP-42 chapter 3.4. Larger spark ignition
engines are fired with natural gas and are covered in Chapter 3.3. In compression ignition
engines, the combustion air is compression heated in the cylinder before the diesel fuel oil is
injected into the cylinder to produce spontaneous combustion. Spontaneous ignition
occurs because the air is above the auto-ignition temperature of the fuel. In spark ignition
engines, the gasoline uses the spark on an electrical discharge to initiate combustion.
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2. SOURCE DESCRIPTION
2.1 CHARACTERIZATION OF THE INDUSTRY
Stationary (nonroad) reciprocating internal combustion (IC) engines are found in a
variety of applications where there is a requirement for mechanical work which can be
derived from the power generated by a shaft. The engine category addressed by Chapter
3.3 covers industrial applications by both gasoline and diesel internal combustion power
plants, such as fork lift trucks, mobile refrigeration units, generators, pumps, heavy-duty
farm and construction engines, and portable well-drilling equipment.
Nonroad engines cover a wide variety of equipment from lawn mowers and chain
saws, to recreational equipment, to agricultural and construction machinery, and industrial
equipment. There is an area of ambiguity in defining which engines are mobile or
stationary because the engine designs can be used in either application. Accordingly,
information for stationary engines may be contained in mobile source documents.
Nonroad engines are not regulated for emissions, and very few currently use
emission control technology. Because of the diversity of nonroad equipment,
characterization of the emissions from nonroad engines is a complex task.
Compression-ignition engines can operate at a higher compression ratio (ratio of
cylinder volume when the piston is at the bottom of its stroke to the volume when it is at
the top of its stroke) than spark-ignited engines because fuel is not present during
compression; thus, there is no danger of premature automatic ignition. Since the thermal
efficiency of an engine rises with increasing pressure ratio (and pressure ratio varies
directly with compression ratio), compression-ignited engines are more efficient than
spark-ignited engines. This increased efficiency is gained at the expense of poorer
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acceleration (response to load changes) and a heavier structure to withstand the higher
pressures.1'2'3
2.2 PROCESS DESCRIPTION4 5
All reciprocating internal combustion (IC) engines operate by the same basic
process. A combustible mixture is first compressed in a small volume between the head of a
piston and its surrounding cylinder. The mixture is then ignited, and the resulting high
pressure products of combustion push the piston through the cylinder. This movement is
converted from linear to rotary motion by a crankshaft. The piston returns, pushing out
exhaust gases, and the cycle is repeated.
Although all reciprocating IC engines follow the same basic process, there are
variations which classify engine types. Engines are generally classified according to: (1)
fuel burned, (2) method of ignition, (3) combustion cycle, and (4) charging method.
2.2.1 Fuel Type
The three primary fuels for stationary reciprocating IC engines are gasoline, diesel
oil (No. 2), and natural gas. Gasoline is used primarily for mobile and portable engines.
Construction sites, farms, and households typically use converted mobile engines for
stationary application because their cost is often less than an engine designed specifically
for stationary purposes. In addition, mobile engine parts and service are readily available,
and gasoline is easily transported to the site. Thus, gasoline is an essential fuel for small
and medium size stationary engines.
Diesel fuel oil is easily transported, and therefore is used in small and medium size
engines. Also, generally higher efficiencies exhibited by diesel engines make diesel oil an
ideal fuel for large engines where operating costs must be minimized. Thus, diesel is the
most versatile fuel for stationary reciprocating engines.
Natural gas is the dominant fuel for large stationary IC engines, which typically
operate pumps or compressors on gas pipelines.
Other fuels are burned in stationary IC engines, but their use is limited. Some
larger engines fire heavy fuel oils, and a few fire waste gaseous or liquid fuels. Gaseous
fuels such as sewer gas are sometimes used at wastewater treatment plants. Stationary IC
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engines can be modified to burn almost any liquid or gaseous fuel if the engine is properly
designed, adjusted and maintained.
2.2.2 Method of Ignition
Ignition is the means of initiating combustion in the engine cycle. There are two
methods used for stationary reciprocating IC engines: compression ignition (CI) and spark
ignition (SI).
In CI engines, combustion air is first compression heated in the cylinder, and diesel
fuel oil is then injected into the hot air. At this point, the temperature of the air is high
enough to cause the fuel to ignite spontaneously (automatic ignition). SI engines initiate
combustion by the spark of an electrical discharge. Usually the fuel is mixed with the air in
a carburetor (for gasoline) or at the intake valve (for natural gas), but occasionally the fuel
is injected into the compressed air in the cylinder. Although all diesel fueled engines are
compression ignited and all gasoline and gas fueled engines are spark ignited, gas can be
used in a CI engine if a small amount of diesel fuel is injected into the compressed gas/air
mixture to burn any mixture ratio of gas and diesel oil, from 6 to 100 percent oil (based on
heating value).
In SI engines, fuel and air are drawn into the cylinder together and are intended to
form a homogeneous mixture of air and vapor by the time of the electrical discharge
(spark) to initiate ignition, toward the end of the compression stroke. After the passage of
a spark, the flame then progresses through the mixture until all of the fuel is consumed. If
the compression ratio of a gasoline engine is significant enough to make the air and fuel
mixture temperature too high, then some of the mixture will autoignite and burn so quickly
that it will rattle the engine parts. This engine noise is called knock (or detonation).
2.2.3 Combustion Cycle
As previously mentioned, the combustion process for stationary reciprocating IC
engines consists of compressing a combustible mixture with a piston, igniting it, and
allowing the high pressures generated to push the piston back. This process may be
accomplished in either four strokes or two strokes of the piston.
In the four-stroke cycle, the sequence of events can be summarized as follows:
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! Intake stroke ~ suction of the air or air and fuel mixture into the
cylinder by the downward motion of the piston through the cylinder.
! Compression stroke — compression of the air or air and fuel mixture,
thereby raising its temperature and reducing its volume.
! Ignition and power (expansion) stroke — combustion and consequent
downward movement of the piston by pressure from the expanding
gases with energy transfer to the crankshaft.
! Exhaust stroke — expulsion of the exhaust gases from the cylinder by
the upward movement of the piston.
Two-stroke engines need only two strokes of the piston or one revolution to complete
a cycle. Thus, there is a power stroke during every revolution instead of every two
revolutions as with four-stroke engines. As the piston moves to the top of the cylinder, air
or an air and fuel mixture is compressed for ignition. Following ignition and combustion,
the piston delivers power as it moves down through the cylinder. Eventually the piston
uncovers the exhaust ports (or exhaust valves open). As the piston begins the next cycle,
exhaust gas continues to be purged from the cylinder, partially by the upward motion of
the piston and partially by the scavenging action of the incoming fresh air. Finally, all
ports are covered (and/or valves closed), and the fresh charge of air or air and fuel is again
compressed for the next cycle.
Two-stroke engines have the advantage of higher horsepower-to-weight ratio
compared to four-stroke engines when both operate at the same speed. In addition, if ports
are used instead of valves, the mechanical design of the engine is simplified. However,
combustion can be better controlled in a four-stroke engine and excess air is not needed to
purge the cylinder. Therefore, four stroke engines tend to be slightly more efficient, and
typically emit less pollutants (primarily unburned HCs) than two- stroke engines. Two-
stroke engines have been discouraged in some applications because of high HC emissions.
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2.2.4 Charging Method
Charging is the method of introducing air or an air and fuel mixture into the
cylinder. Three methods are commonly used: natural aspiration, turbocharging, and
blower-scavenged.
A naturally aspirated engine uses the vacuum created behind the moving piston
during the intake stroke to suck in the fresh air charge. This process tends to be somewhat
inefficient, however, since the actual amount of air drawn into the cylinder is only about 50
to 75 percent of the displaced volume. A more efficient method of charging is to pressurize
the air or air and fuel mixture and force it into the cylinder with either a turbocharger or a
supercharger. The turbocharger is powered by a turbine that is driven by the energy in the
relatively hot exhaust gases, while a supercharger is driven off the engine crankshaft. Air
pressurization increases the power density, or power output per unit weight (or volume) of
the engine, since more air mass can be introduced into the cylinder. As air pressure
increases, its temperature also rises because of the action of the compressor on the air.
Therefore, the pressurized air is often cooled before entering the cylinder to further
increase power by allowing more air mass to be introduced into the cylinder. This process
is called intercooling or aftercooling. Two stroke engines are often aircharged by a blower,
which also aids in purging the exhaust gases. Such systems are called blower-scavenged.
This method is less efficient than turbocharging because the blower produces less pressure
than a turbine. However, high volumetric flow rates are achieved, effectively purging the
cylinder of exhaust gases.
In a CI engine, fuel is injected into the cylinder near the end of the compression
stroke; whereas, in a SI engine, the fuel is usually added to the air downstream of the
turbocharger if any is used, and before the mixture enters the cylinder. This is done with a
carburetor. However, some SI engines (particularly large natural gas fueled ones) inject
the fuel into the intake manifold just ahead of the valves, or into the cylinder as done with
CI engines.
Two methods of injection are commonly used. Direct injection places the fuel
directly into the cylinder and the principal combustion chamber. These units are also
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called open chamber engines because combustion takes place in the open volume between
the top of the piston and the cylinder. In contrast is indirect injection, where combustion
begins in a fuel rich (oxygen deficient) atmosphere in a smaller antechamber and then
expands into the cooler, excess air region of the main chamber. These latter engines are
also called divided or precombustion chamber systems.
2.3 EMISSIONS
Most of the pollutants from IC engines are emitted through the exhaust. However,
some HCs escape from the crankcase as a result of blowby (gases which are vented from the
oil pan after they have escaped from the cylinder past the piston rings) and from the fuel
tank and carburetor because of evaporation. Nearly all of the HCs from diesel (CI) engines
enter the atmosphere from the exhaust. Crankcase blowby is minor because hydrocarbons
are not present during compression of the charge. Evaporative losses are insignificant in
diesel engines due to the low volatility of diesel fuels. In general, evaporative losses are also
negligible in engines using gaseous fuels because these engines receive their fuel
continuously from a pipe rather than via a fuel storage tank and fuel pump. In gasoline-
fueled engines, however, 20 to 25 percent of the total hydrocarbon emissions from
uncontrolled engines come from crankcase blowby and another 10 to 15 percent from
evaporation of the fuel in the storage tank and the carburetor. However, crankcase blowby
emissions can be virtually eliminated through the simple expedient use of the positive
crankcase ventilation (PCV) valve. Additional fugitive emissions are possible from fuel
storage and transport. These emissions are covered in AP-42 Chapter 4.
The primary pollutants from internal combustion engines are oxides of nitrogen
(NOx), hydrocarbons and other organic compounds, CO, and particulates, which include
both visible (smoke) and nonvisible emissions. Nitrogen oxide formation is directly related
to high pressures and temperatures during the combustion process and to the nitrogen
content, if any, of the fuel. The other pollutants, HC, CO, and smoke, are primarily the
result of incomplete combustion. Ash and metallic additives in the fuel also contribute to
the particulate content of the exhaust. Sulfur oxides also appear in the exhaust from IC
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engines. The sulfur compounds, mainly sulfur dioxide (S02), are directly related to the
sulfur content of the fuel.2
2.3.1 Nitrogen Oxides
Nitrogen oxide formation occurs by two fundamentally different mechanisms. The
predominant mechanism with internal combustion engines is thermal NOx which arises
from the thermal dissociation and subsequent reaction of nitrogen (N2) and oxygen (02)
molecules in the combustion air. Most thermal NOx is formed in the high temperature
region of the flame from dissociated molecular nitrogen in the combustion air. Some NOx,
called prompt NOx, is formed in the early part of the flame from reaction of nitrogen
intermediary species, and HC radicals in the flame. The second mechanism, fuel NOx,
stems from the evolution and reaction of fuel-bound nitrogen compounds with oxygen.
Natural gas, gasoline, and most distillate oils have no chemically-bound fuel N2 and
essentially all NOx formed is thermal NOx. Residual oils and many liquid wastes have fuel-
bound N2 and when these are fired in engines, NOx is formed by both mechanisms. The
formation of prompt NOx is only significant in very fuel-rich flames and is of no significant
importance with relation to reciprocating IC engines.
At high temperatures (thermal NOx), both N2 and 02 molecules in the combustion
air absorb the heat energy up to the point where they are dissociated into their respective
atomic states, N and O. The subsequent reaction of these atoms to create thermal NOx is
described by the Zeldovich mechanism:
N2 + O - NO + N
N + 02 - NO + O
The rates of these reactions are highly dependent upon the stoichiometric ratio,
combustion temperature, and residence time at the combustion temperature.
The maximum thermal NOx production occurs at a slightly lean fuel mixture ratio
because of the excess availability of oxygen for reaction. The control of stoichiometry is
critical in achieving reductions in thermal NOx. The thermal NOx generation decreases
rapidly as the temperature drops below the adiabatic temperature (for a given
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stoichiometry). Maximum reduction of thermal NOx generation can thus be achieved by
control of both the combustion temperature and the stoichiometry.
With fuel NOx, the nitrogen compounds (primarily organic) contained in the fuels
are evolved and react to form NOx. The degree of oxidation of the nitrogen in the fuel is
strongly dependent upon the stoichiometric ratio and fuel nitrogen concentration, and
weakly dependent upon the flame temperature and the nature of the organic nitrogen
compound. It is the weak influence of temperature on gas-phase NOx conversion that
reduces the effectiveness of NOx controls which rely on temperature effects in the
combustion of nitrogen-bearing fuels. Here, as with thermal NOx, controlling excess 02
(stoichiometry) is an important part of controlling NOx formation.
Because of the high flame temperatures and pressures of IC engines, the majority of
NOx formed is thermal NOx. As diesel fuel and natural gas are the predominate fuels for
this source, little fuel NOx is formed, except in engines that fire residual and/or crude oils.
When fuel is injected into the cylinder, it undergoes a series of reactions that lead to
ignition. The time between the start of injection of the fuel and the start of combustion (as
measured by the onset of energy release) is called the ignition delay. Initial combustion
occurs around the periphery of the fuel jet, where the air/fuel ratio is close to the
stoichiometric ratio. During ignition delay, some of the fuel is premixed with air and
evaporates. After ignition occurs, the premixed charge burns extremely rapidly, thereby
quickly releasing energy. Most of the burning takes place as a diffusion flame after the
premixed charge has burned.
Nitrogen oxide emissions are directly affected by the amount of premixing which, in
turn, is a function of the ignition delay. When the ignition delay is large, there is more
premixing and a greater energy release rate at the start of combustion. This generally leads
to higher temperatures and, accordingly, higher NOx emissions.
In general, engine load does not have a profound effect on the brake-specific (NOx
rate to power output ratio) NOx emission rates for diesel-fueled engines, although the total
mass emission rates increase as the engine load increases. At very low engine loads, almost
all of the energy is released during the premixed stage. Consequently, brake-specific
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emissions under these conditions are relatively high. As load increases, the amount of
premixed burning remains relatively constant while the amount of diffusion burning
increases linearly. The amount of NOx produced during this stage is proportional to the
amount of fuel consumed because most of the diffusion burning takes place at
stoichiometric conditions. Thus, as engine load increases, the concentration of NOx in the
exhaust gas increases. However, the brake-specific NOx emission rate remains roughly the
same since power output also increases by the same factor.
Brake-specific NOx emission rates for dual-fuel compression ignition engines are
sensitive to load. Emission rates are greatest at high loads. Dual-fuel engines generally
burn a homogeneous charge of fuel. A CI engine is unthrottled; the air/fuel ratio of the
charge decreases as engine load increases. At high loads, combustion occurs closer to the
point where maximum NOx is produced.
Preignition chamber engines have lower baseline NOx emissions than direct fuel
injection engines. Shorter ignition delay combined with the generally richer combustion
conditions in the preignition chamber results in smoother combustion and lower peak
temperatures. In addition, there are significant heat transfer losses as the combustion gas
goes from the preignition chamber to the main combustion chamber, lowering peak
temperatures.6
2.3.2 Total Organic Compounds (Hydrocarbons)
The pollutants commonly classified as hydrocarbons are composed of a wide variety
of organic compounds. They are discharged into the atmosphere when some of the fuel
remains unburned or is only partially burned during the combustion process. Most
unburned hydrocarbon emissions result from fuel droplets that were transported or
injected into the quench layer during combustion. This is the region immediately adjacent
to the combustion chamber surfaces, where heat transfer outward through the cylinder
walls causes the mixture temperatures to be too low to support combustion.
Partially burned hydrocarbons can occur for a number of reasons:
! Poor air and fuel homogeneity due to incomplete mixing, before or
during combustion.
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! Incorrect air/fuel ratios in the cylinder during combustion due to
maladjustment of the engine fuel system.
! Excessively large fuel droplets (diesel engines).
! Low cylinder temperature due to excessive cooling (quenching) through
the walls or early cooling of the gases by expansion of the combustion
volume caused by piston motion before combustion is completed.
All of these conditions can be caused by either poor maintenance or faulty design.
Therefore, the lowest emissions will be achieved only by proper maintenance of engines
designed specifically for low emissions.2
2.3.3 Carbon Monoxide
Carbon monoxide is a colorless, odorless, relatively inert gas formed as an
intermediate combustion product that appears in the exhaust when the reaction of CO to
C02 cannot proceed to completion. This situation occurs if there is a lack of available
oxygen near the hydrocarbon (fuel) molecule during combustion, if the gas temperature is
too low, or if the residence time in the cylinder is too short. The oxidation rate of CO is
limited by reaction kinetics and, as a consequence, can be accelerated only to a certain
extent by improvements in air and fuel mixing during the combustion process.
Carbon monoxide is a primary (directly emitted) pollutant, unlike ozone and other
secondary pollutants which are formed in the atmosphere by photochemical reactions
(reactions that require light). Carbon monoxide combines with the hemoglobin in blood,
preventing it from carrying needed oxygen, and adversely affects the ability to perform
exercise.2'7
2.3.4 Smoke. Particulate Matter, and PM-10
White, blue, and black smoke may be emitted from IC engines. Liquid particulates
appear as white smoke in the exhaust during an engine cold start, idling, or low load
operation. These are formed in the quench layer adjacent to the cylinder walls, where the
temperature is not high enough to ignite the fuel. The liquid particulate consist primarily
of raw fuel with some partially burned hydrocarbons and lubricating oil. White smoke
emissions are generally associated with older gasoline engines and are rarely seen in the
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exhaust from diesel or gas-fueled units. They cease when the engine reaches its normal
operating temperature and can be minimized during low demand situations by proper idle
adjustment.
Blue smoke is emitted when lubricating oil leaks, often past worn piston rings, into
the combustion chamber and is partially burned. Proper maintenance is the most effective
method of preventing blue smoke emissions from all types of IC engines.
The primary constituent of black smoke is agglomerated carbon particles (soot).
These form in a two-step process in regions of the combustion mixture that are oxygen
deficient. First the hydrocarbons decompose into acetylene and hydrogen in the high
temperature regions of the cylinder. Then, when the local gas temperature decreases as the
piston moves down and the gases expand, the acetylene condenses and releases its hydrogen
atoms. As a result, pure carbon particles are created. This mechanism of formation is
associated with the low air/fuel ratio conditions that commonly exist at the core of the
injected fuel spray, in the center of large individual fuel droplets, and in fuel layers along
the walls. The formation of particles from this source can be reduced by designing the fuel
injector to provide for an even distribution of fine fuel droplets such that they do not
impinge on the cylinder walls.
Once formed, the carbon will combine with oxygen to form CO and C02 if it is still
at an elevated temperature. Since the temperature of the exhaust system is too low for this
oxidation to occur, soot that leaves the combustion chamber before it has had the
opportunity to oxidize completely will be discharged as visible particles. Discharge is
greatest when the engine is operating at rich air/fuel ratios, such as at rated power and
speed, because soot formation is very sensitive to the need for oxygen. Therefore, naturally
aspirated engines are likely to have higher smoke levels than turbocharged engines, which
operate at leaner air/fuel ratios.2
Exposure to particulate matter less than 10 micrometers in aerodynamic diameter
(PM-10) can result in both short and long term reductions in lung function because they
are too small to be trapped by the nose and large enough that some deposition in the lungs
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occurs. Also, PM-10 is the pollutant that causes most of the air pollution-induced
reduction in visibility.7
2.3.5 Sulfur Oxides
Sulfur oxide emissions are a function of only the sulfur content in the fuel rather
than any combustion variables. In fact, during the combustion process, essentially all the
sulfur in the fuel is oxidized to S02. The oxidation of S02 gives sulfur trioxide (S03), which
reacts with water to give sulfuric acid (H2S04), a contributor to acid precipitation. Sulfuric
acid reacts with basic substances to give sulfates, which are fine particulates that contribute
to PM-10 and visibility reduction. Sulfur oxide emissions also contribute to corrosion of
the engine parts.2'7
2.3.6 Carbon Dioxide
Concern about the increasing release of greenhouse gases such as C02 has grown
out of research that documents the buildup of gases in the atmosphere and estimates the
implications of continued accumulations. Carbon dioxide is largely transparent to
incoming solar radiation, but can absorb infrared radiation reemitted by the Earth.
Because of this energy trapping property, such a gas is referred to as a greenhouse gas.8
2.4 CONTROL TECHNOLOGIES
The control development and regulation has been less extensive for industrial
engines than for boilers because industrial engines are a relatively small emission source
compared to boilers. Controls for hydrocarbons and CO have been partly adopted from
mobile sources. Controls for NOx have mostly focused on modifications to the combustion
process. Postcombustion catalytic reduction is becoming available, but its use is limited
because of cost.
2.4.1 Engine Controls1'6'9
2.4.1.1 Combustion Cycle. Reciprocating IC engines may be either two- or four-
stroke cycle. During combustion, emissions from either type are essentially identical.
However, during the charging of a two-stroke engine, several events take place. On
noninjected engines, the scavenging air, which purges the cylinder of exhaust gases and
provides the combustion air, can also sweep out part of the fuel charge. Thus, carbureted
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two-cycle engines often have higher organic compound emissions in the form of unburned
fuel than fuel injected engines.
The two-stoke engine can also have lower NOx emissions than a four-stroke engine.
If the cylinder is not completely purged of exhaust gases, the result is internal exhaust gas
recirculation (EGR). The remaining inert exhaust gases absorb energy from combustion,
lowering peak temperatures, and thereby lowering NOx. Internal EGR can reduce NOx
emissions by 4 to 37 percent. External EGR (turbocharged models) can have reductions
varying from 25 to 34 percent. These reductions are obtained with exhaust gas
recirculation rates of 6.5 to 12 percent. At 6 percent EGR, NOx reductions range from 10
to 22 percent. In general, fuel consumption remains unchanged for EGR rates less than 12
percent.
2.4.1.2 Injection Timing Retard. Ignition in a normally adjusted IC engine is set to
occur shortly before the piston reaches its uppermost position [top dead center (TDC)]. At
TDC, the air or air and fuel mixture is at maximum compression. The timing of the start of
injection or of the spark is given in terms of the number of degrees that the crankshaft
must still rotate between this event and the arrival of the piston at TDC.
Retarding the timing beyond TDC, the point of optimum power and fuel
consumption, reduces the rate of NOx production. Retarding causes more of the
combustion to occur later in the cycle, during the expansion stroke, thus lowering peak
temperatures, pressures, and residence times. The efficiency loss is identifiable by the
increase in fuel flow needed to maintain rated power output. This practice carries with it a
fuel consumption penalty of 5 to 8 percent and the potential of excessive smoke. Typical
retard values range from 2° to 6° depending on the engine. Beyond these levels, fuel
consumption increases rapidly, power drops, and misfiring occurs. Also, TOC, CO, and
visible emissions increase, and elevated exhaust temperatures shorten exhaust valves and
turbocharger service lives. Increasing the fuel injection rate has been used on some diesel
systems to partially mitigate the CO and TOC emissions and fuel consumption effects of
retarded injection timing. A high injection rate, however, results in increased mixing of air
and fuel and a subsequently hotter flame at the initiation of combustion. Therefore, there
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is a NOx trade-off with this modification. Injection timing retard is an applicable control
with all IC engine fuels.
The reported level of control is in the range of 0.6 to 8.5 percent reduction for each
degree of retard. On the average, diesel engines reduce NOx by 25 percent for 4° of retard
and 40 percent for 8° of retard. Fuel usage increases approximately 2 percent at 4° retard,
whereas 8° of retard raises fuel usage by about 6 percent.
2.4.1.3 Prelgnition Chamber Combustion - "Clean Burn" Technology. The use of a
preignition chamber can improve fuel efficiency and reduce NOx emissions. The system is
designed to burn lean air/fuel mixtures. The fuel charge is introduced into the prechamber
as a rich mixture and ignited by a sparkplug. Since it burns in the absence of excess
oxygen, NOx formation is inhibited. This "torch" of burning fuel expands into the power
cylinder where it thoroughly ignites a lean mixture at reduced temperatures. Therefore,
combustion is completed in an overall lean mixture at temperatures that are adequate for
combustion but below those where high NOx formation occurs. This NOx control has
currently been developed for natural gas-fired engines only.
2.4.1.4 Air to Fuel Ratio. In injection type engines, which include all diesel and
many dual fuel and gas varieties, the air/fuel ratio for each cylinder can be adjusted by
controlling the amount of fuel that enters each cylinder. These engines are therefore
operated lean where combustion is most efficient and fuel consumption is optimum.
At air/fuel ratios below stoichiometric (rich), combustion occurs under conditions of
insufficient oxygen and thus unburned HC emission increase. Carbon monoxide increases
because carbon is not sufficiently oxidized to C02. Nitrogen oxides decrease both because
of insufficient oxygen and lower temperatures.
At air/fuel ratios above stoichiometric (lean), combustion occurs under conditions of
excess oxygen, thus essentially all carbon is oxidized to C02. Nitrogen oxides first increase
rapidly with the air/fuel ratio near stoichiometric, because of the excess oxygen and peak
temperatures, then decrease rapidly with increasing air/fuel ratio as the excess air cools
peak combustion temperatures. Hydrocarbons stay at a low level, then begin to increase as
the air/fuel ratio is increased because the lower temperatures inhibit combustion.
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The choice of lean or rich operation often depends on engine use. Rich operating
(meaning close to stoichiometry) engines give quicker response to changing conditions
and/or loads, and also produce maximum power. The most practical use of air/fuel ratio
adjustment as a control technique is to change the setting toward leaner operation. The
oxygen availability will increase but so will the capability of the air and combustion
products to absorb heat. Consequently, the peak temperature will fall, resulting in lower
NOx formation rates. The limiting factor for lean operation is the increased emissions of
hydrocarbons at the lower temperatures. Small changes in the air/fuel ratio, approximately
10 percent, can reduce NOx by about 30 percent with a fuel penalty of about 5 percent.
Charging method is important because it often limits the range of the air/fuel ratio.
Naturally aspirated carbureted engines generally must operate with overall air/fuel
equivalence ratios, defined as {(A/F)stoichiometric}/{(A/F)actual}, greater than 0.7 because poor
distribution among cylinders will allow some cylinders to go excessively lean. In contrast,
turbocharged fuel injected engines with precise control of air/fuel ratio to each cylinder can
operate at equivalence ratios of 0.5 to 0.3 without increasing hydrocarbon emissions
significantly. Some blower-scavenged engines operate at equivalence ratios below 0.25,
although the actual ratio inside the cylinder is usually higher.
2.4.1.5 Water Injection. Water injection has extensive application to NOx control
with combustion turbines. Water injection reduces NOx emissions but may increase HC
emissions because of the lower peak temperature and the increased possibility that burnout
reactions will be quenched before burnout occurs. Carbon monoxide appears to be less
affected by water injection. Wet control effectiveness correlates inversely with excess air
levels. Since wet controls reduce peak temperature by increasing the charge mass (and
through absorption of the latent heat of vaporization), the technique is more effective in a
low excess air system than in one with much excess air and hence, much thermal mass. At
high excess air, the incremental temperature reduction is less although the initial
temperature may also be less because of the larger thermal mass. The application of this
control to IC engines has been limited because of inaccessibility of water injection. Some
applications of wet controls have been made in the development of water-fuel emulsions.
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2.4.1.6 Derating. An engine can be derated by restricting its operation to lower
than normal levels of power production for the given application. Derating reduces
cylinder pressures and temperatures and thus lowers NOx formation rates. Although NOx
exhaust concentrations (i.e., moles of NOx per mole of exhaust) are reduced, it is quite
possible for this reduction to be no greater than the power decrease. In such a case, brake
specific emissions (i.e., g/hp-hr) are not reduced. This is especially true for four-stroke
turbocharged engines. In addition, air/fuel ratios change less with derating for
turbocharged engines than for naturally aspirated or blower scavenged units. Thus, NOx
emissions are less responsive to derating for turbocharged engines. Derating also reduces
the engine's operating temperature, which can result in higher CO and HC emissions.
One significant disadvantage of derating is that spare engine capacity may be
needed which could require a large capital investment. For new engines, derating can be
applied by designing the engine to operate under derated conditions. This could mean a
larger, more expensive engine to do the same job.
2.4.2 Post-Combustion Control6'10'11
2.4.2.1 Selective Catalytic Reduction. In the selective catalytic reduction (SCR)
process, anhydrous ammonia (NH3) gas, usually diluted with air or steam, is injected
through a grid system into the exhaust gas stream upstream of a catalyst. On the catalyst
surface, the NH3 reacts with NOx to form molecular nitrogen and water. Depending on
system design, NOx removal of 80 to 90 percent and higher are achievable under idealized
conditions. The global reactions that occur in the presence of the catalyst are the following:
4NH3 + 4NO + 02 - 4N2 + 6H20
4NH3 + 2N02 + 02 - 3N2 + 6H20
The reaction of NH3 and NOx is favored by the presence of excess oxygen (fuel lean
conditions). The primary variable affecting NOx reduction is temperature. Optimum NOx
reduction occurs at catalyst bed temperatures between 600 and 750 °F for conventional
(vanadium or titanium-based) catalyst types, and between 470 and 510 °F for platinum
catalysts. Performance for a given catalyst depends largely on the temperature of the
exhaust gas being treated. A given catalyst exhibits optimum performance between a
2-16
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temperature range of about ±50 °F for applications where flue gas 02 concentrations are
greater than 1 percent. Below this optimum temperature range, the catalyst activity is
greatly reduced, allowing unreacted NH3 to slip through. Above 850 °F, NH3 begins to be
oxidized to form additional NOx. The ammonia oxidation to NOx increases with increasing
temperature. Depending on the catalyst substrate material, the catalyst may be quickly
damaged because of thermal stress at temperatures in excess of 850 °F. It is important to
have stable operations and uniform flue gas temperatures for this process in order to
achieve optimum NOx control.
The optimal effectiveness of the catalytic process is also dependent on the N03/N0x
ratio. Ammonia injection rates must be controlled to give an optimum NH3/NOx mole ratio
of about 1:1. As the mole ratio of NH3/NOx increases the level of approximately 1:1, the
NOx reduction increases. Operating with ammonia injection above this level or with
insufficient catalyst volume will result in unreacted NH3 slipping through the catalyst bed.
On-stream analyzers and quick feedback control are required to optimize the NOx removal
and minimize NH3 emissions.
Other variables which affect NOx reduction are space velocity, the ratio of flue gas
flow rate to catalyst volume, or the inverse of residence time. For a given catalyst volume,
increased flue gas rate decreases the conversion NOx. Conversely, for a given flue gas flow
rate, increased catalyst volume improves the NOx removal effectiveness.
Site-specific factors including operating temperatures and fuel type affect the
performance and emission rates achievable with SCR. There are a number of operating
considerations with SCR. First, potential catalyst poisoning by either metals, acid gases, or
particulate entrainment is detrimental. The potential loss of catalyst activity due to these
fuel effects results in the use of an excess of catalyst to maintain the required process
efficiency over an extended period of time. Second, NH3 emissions result. In a properly
designed and controlled system, NH3 emissions should be less than 10 ppm. Also, flue gas
temperatures may not be in the proper operating range for optimum NOx reduction. This
problem may be aggravated by load changes or air/fuel ratio changes, and may necessitate
costly heat exchange equipment for adequate NOx reduction or acceptable efficiency. An
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increase in back pressure due to pressure drop across the catalyst results in a decrease in
fuel efficiency. In addition, the formation of ammonium sulfate and bisulfate in the
presence of S03 and unreacted NH3 presents corrosion and plugging concerns.
2.4.2.2 Nonselective Catalytic Reduction. Nonselective catalytic reduction (NSCR)
systems are often referred to as three-way conversion catalyst systems since they reduce
NOx, unburned hydrocarbon, and CO simultaneously. When the overall mixture supplied
to the engine is weak, catalysis will favor oxidation of hydrocarbons and CO to C02 and
water vapor but will not affect NOx. To operate properly, the combustion process must
occur with an air/fuel ratio slightly fuel-rich of stoichiometric. Under this condition, in the
presence of the catalyst, NOx is reduced by the CO, resulting in nitrogen and C02. Sulfur
resistant catalysts supports of titanium, molybdenum or tungsten are available for S03-
laden stream applications. Deposits are controlled by control of NH3 slip to below 5 ppmv.
Nonselective catalytic reduction systems primarily utilize the following reaction in
reducing NOx:
2CO + 2NOx - 2C02 + N2
The catalyst used to promote this reaction is generally a mixture of platinum and
rhodium. The catalyst operating temperature limits are 700 to 1,500 °F, with 800 to
1,200 °F being the most desirable. Temperatures above 1,500 °F result in catalyst
sintering.
Typical NOx conversion ranges from 80 to 95 percent with corresponding decreases
in CO and HC. Potential problems associated with NSCR applications include catalyst
poisoning by oil additives (e.g., phosphorous and zinc) and inadequate air/fuel ratio
controllers. Nonselective catalytic reduction is currently limited to IC engines with fuel-
rich ignition systems.
2.4.2.3 Diesel Particulate Traps.12'13 The particulate trap consists of a filter
positioned in the exhaust stream designed to collect a significant fraction of the particulate
emissions while allowing the exhaust gases to pass through the system. The operating
principle of the trap is based on the capture (the volume of particulate matter emitted is
sufficient to fill up and plug a reasonably sized filter over time) and periodic incineration
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(or regeneration) of the carbonaceous exhaust particulates. The regeneration is often
achieved through the use of heat provided by a variety of sources (fueled burners, electric
heaters, engine intake and throttling). Regeneration is usually triggered after reaching a
preestablished pressure drop measured across the trap which is often made of a wallflow
honeycomb structure. Diesel traps have been developed most extensively for mobile source
applications because of greater regulatory activity in that sector. Application to stationary
engines has lagged mobile source applications.
2.4.3 Control Technology Applications
From a NOx control viewpoint, the most important distinction between different
engine models and types for reciprocating engines is rich-burn versus lean-burn. Exhaust
from rich-burn engines has little or no excess air while the exhaust from lean burn engines
is characterized with medium to high levels of 02.
In diesel oil-fueled engines, the most common engine control techniques employed
include injection timing retard and Clean Burn. Selective catalytic reduction technology
has been applied to lean-burn reciprocating, diesel engines where the exhaust gas 02
concentrations are high as the SCR reaction mechanisms require presence of oxygen.
Concerns persist over engine air-fuel controllability, catalyst durability, and ammonia slip.
Application of NSCR requires fuel-rich engine operation or the addition of reducing agents
in the flue gas upstream of the catalyst. Therefore, efficient application of this technology
is limited to rich-burn engines (gasoline).
The Manufacturers of Emission Controls Association (MECA) state that catalytic
oxidation controls for CO emissions are achieving 90 to 99 percent reduction for
commercial applications.10 For NOx control, limited experience with SCR technology on
lean-burn engines has shown potential for 90 to 95 percent control, but long term
experience under field conditions is sparse. Nonselective catalytic reduction on rich-burn
engines has achieved 90 to 99 percent control efficiency levels, largely in response to
regulations in California. There is also commercial availability of VOC controls for diesel,
lean burn, and rich burn IC engines, mostly adapted from mobile sources.
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Several commercial processes currently exist to remove carbon dioxide. However,
currently, there is no regulatory or economic incentive for utilities or private industry to
remove carbon dioxide. Large scale carbon dioxide removal and disposal processes are
very expensive.14
As on-road engines have become cleaner to meet increasingly stringent emissions
requirements, the off-road engines will become a relatively more significant contributor to
nonattainment of air quality goals. The application of on-road engines experience and
hardware can be used to accelerate the development process of improving emissions from
off-road engines. Improvements in the emissions of engines in off-road service can be made
by appropriate application of on-road technology (such as fuel injector tip geometry,
injection timing, and charge air temperature).15
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REFERENCES FOR CHAPTER 2
1. Lips, H.I., J.A. Gotterba, and K.J. Lim, "Environmental Assessment of Combustion
Modification Controls for Stationary Internal Combustion Engines," EPA-600/7-81-
127, Industrial Environmental Research Laboratory, Office of Environmental
Engineering and Technology, Office of Air Quality Planning and Standards, U.S
Environmental Protection Agency, Research Triangle Park, NC, July 1981.
2. "Standards Support and Environmental Impact Statement, Volume I: Stationary
Internal Combustion Engines," EPA-450/2-78-125a, Emission Standards and
Engineering Division, Office of Air, Noise, and Radiation, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, NC, July 1979.
3. "Nonroad Engine and Vehicle Emission Study-Report," EPA-460/3-91-02,
Certification Division, Office of Mobile Sources, Office of Air & Radiation, U.S
Environmental Protection Agency, November 1991.
4. Arcoumanis, C., editor, "Internal Combustion Engines," Academic Press, San
Diego, CA, 1988.
5. Ferguson, C., "Internal Combustion Engines: Applied Thermosciences," John
Wiley & Sons, New York, NY, 1986.
6. Campbell, L.M., D.K. Stone, and G.S. Shareef, "Sourcebook: NOx Control
Technology Data," EPA-600/2-91-029, Radian for Control Technology Center,
Emission Standards Division, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, July 1991.
7. Hoggan, M., S. Cohanim, R. Sin, M. Hsu, and S. Tom, "Air Quality Trends in
California's South Coast and Southeast Desert Air Basins, 1976-1990, Air Quality
Management Plan, Appendix II-B," South Coast Air Quality Management District,
July 1991.
8. "Limiting Net Greenhouse Gas Emissions in the United States, Volume II: Energy
Responses," report for the Office of Environmental Analysis, Office of Policy,
Planning and analysis, Department of Energy (DOE), DOE/PE-0101 Vol. II,
September 1991.
9. Castaldini, C., "Environmental Assessment of NOx Control on a Compression
Ignition Large Bore Reciprocating Internal Combustion Engine, Volume I:
Technical Results," EPA-600/7-86/001a, pp. 3-1 to 3-10, Combustion Research
2-21
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REFERENCES FOR CHAPTER 2 (Continued)
Branch of the Energy Assessment and Control Division, Industrial Environmental
Research Laboratory, Office of Research and Development, U.S. Environmental
Protection Agency, Washington, D.C., April 1984.
10. Catalysts for Air Pollution Control, brochure by the Manufacturers of Emission
Controls Association (MECA), Washington, D.C., March 1992.
11. Castaldini, C., and L.R. Waterland, "Environmental Assessment of a Reciprocating
Engine Retrofitted with Selective Catalytic Reduction, Volume I: Technical
Results," EPA/600/7-86/014a, Air and Energy Engineering Research Laboratories,
Office of Research and Development, U.S. Environmental Protection Agency,
Research Triangle Park, NC, December 1984.
12. Walsh, M.P., Worldwide Developments in Motor Vehicle Diesel Particulate Control,
SAE report #890168.
13. Khair, M.K., Progress in Diesel Engine Emissions Control, ASME report #92-ICE-
14.
14. "Limiting Net Greenhouse Gas Emissions in the United States, Volume I: Energy
Technologies," report for the Office of Environmental Analysis, Office of Policy,
Planning and Analysis, Department of Energy (DOE), DOE/PE-0101 vol. I,
September 1991.
15. Swenson, K.R., "Application of On-Highway Emissions Reduction Technology to an
Off-Highway Engine, Final Report Volume I," prepared by Southwest Research
Institute for the Santa Barbara county Air Pollution Control District, SwRI Project
#03-3354-200, November 1991.
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3. EMISSION DATA REVIEW AND ANALYSIS PROCEDURES
This section reviews the literature search and data evaluation procedures used to
identify and review documents or other sources of test data. It also summarizes which
types of data sources were identified for specific pollutant types and summarizes the
criteria of data quality to rate the level of confidence of the data in terms of method used to
sample and reporting of results. Emissions data were reviewed and analyzed based on EPA
guidelines.1 Data from all sources were entered into summary tables to help calculate
average emission factors and identify data gaps. Quality ratings were applied to both
individual data sets and overall emission factors. The criteria for rating individual
emissions data were as follows:
Definition of Data Rankings:
A - When tests are performed by a sound methodology and are reported in enough
detail for adequate validation. These tests are not necessarily EPA reference
method tests, although such reference methods are preferred and certainly to
be used as a guide.
B - When tests are performed by a generally sound methodology, but they lack
enough detail for adequate validation.
C - When tests are based on an untested or new methodology or are lacking a
significant amount of background data.
D - When tests are based on a generally unacceptable method, but the method may
provide an order-of-magnitude value for the source, or no background data is
provided at all.
Emission factor criteria are discussed in Chapter 4.
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3.1 LITERATURE SEARCH AND EVALUATION
The literature search started with reviewing the documents used in the previous
revision of AP-42 Chapter 3.3. The prior background document showed that the previous
emission factors were essentially based on one report, "Exhaust Emissions from
Uncontrolled Vehicles and Related Equipment Using Internal Combustion Engines, Final
Report, Part 5: Heavy-Duty Farm, Construction, and Industrial Engines."2'3 The emission
factors found in this report were based on the emissions testing of eight diesels and four
gasoline engines. After reviewing the background document, an internal and external
literature search was conducted.
Several different approaches were undertaken to obtain literature and data to
facilitate update of the emission factors. The applicable references and sources (listed at
the end of this chapter) were obtained and reviewed along with documents found through a
"Dialogue" computer abstract search, an in-house data search, an EPA library search, an
Electric Power Research Institute (EPRI) library search, periodicals, and contacts with
trade organizations, manufacturers, and local, state, and federal air regulatory agencies. A
complete list of contacts made can be found in Appendix B. Table 3-1 shows an evaluation
of the references found.
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TABLE 3-1. EVALUATION OF REFERENCES
Reference
Used in
AP-42
revision
Why/Why Not
Parameter of Interest
Useable Raw
Emission
Factor Data
3
Yes
Used in previous revision/source test data on diesel/gasoline engines;
confirmatory checks made
Criteria
Yes
4
Yes
Shows that prior AP-42 data is representative
Criteria
No
5
Yes
Evaluates which data set is currently best available
Criteria
No
6
Yes
Compilation of emission databases/population & duty-cycles
All
Yes
7
Yes
Good small engine (<20 hp) data
Criteria
Yes
8
Yes
Emissions data
Criteria
Yes
9
Yes
Emissions data
Criteria
Yes
10
Yes
Review of non-road emissions
All
Yes
11
No
Controlled emissions. Insufficient data to convert units
Criteria
No
12
Yes
Compilation of emissions data and control performance
Criteria
No
13
Yes
Summary of combustion control performance
NOx
No
14
Yes
Summary of NOx control performance
NOx
No
15
Yes
Review of criteria pollutant properties
Criteria
No
16
Yes
Review of large diesel engine properties and exhaust
Criteria, Non-Criteria
No
17
Yes
Data on selective catalytic reduction performance (gas)
NOx
No
18
Yes
Air toxics source test data
C02, Organics
Yes
19
Yes
Air toxics source test data
C02, Organics
Yes
20
No
Uses the same data from Reference 12
Criteria
Yes
21
Yes
Summary of test results. Vol. II data supplement needed.
Criteria
Yes
22
Yes
Review of non-road emissions of air toxics
Air toxics
Yes
-------
REFERENCES FOR CHAPTER 3
1. Technical Procedures for Developing AP-42 Emission Factors and Preparing AP-42
Sections (Draft), Emission Inventory Branch, Technical Support Division, Office of
Air and Radiation, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, March 6,1992.
2. Compilation of Air Pollutant Emission Factors, Volume II, EPA Report No. AP-42,
Fourth Edition, September 1985, Office of Air Quality Planning and Standards,
U.S. Environmental Protection Agency, Research Triangle Park, NC.
3. Hare, C.T. and K.J. Springer, "Exhaust Emissions from Uncontrolled Vehicles and
Related Equipment Using Internal Combustion Engines, (Final Report), Part 5:
Heavy-Duty Farm, Construction, and Industrial Engines," prepared by Southwest
Research Institute (San Antonio, Texas), under Contract No. EHS 70-108,
Publication # APTD-1494, for U.S. Environmental Protection Agency, Research
Triangle Park, NC, October 1973.
4. "Emission Assessment of Conventional Stationary Combustion Systems, Volume II:
Internal Combustion Sources," EPA-600/7-79-029c, February 1979.
5. Weaver, C.S., "Feasibility and Cost-Effectiveness of Controlling Emissions From
Diesel Engines in Rail, Marine, Construction, Farm, and Other Mobile Off-Highway
Equipment," Radian Corp., DCN: 87-258-012-25-02, Final report under EPA
Contract No. 68-01-7288, Work Assignment 25, Office of Policy Analysis.
6. "Nonroad Engine and Vehicle Emission Study-Report," EPA-460/3-91-02,
Certification Division, Office of Mobile Sources, Office of Air & Radiation, U.S.
Environmental Protection Agency, November 1991.
7. White, J.J., J.N. Carroll, C.T. Hare, and J.G. Lourenco, "Emission Factors for
Small Utility Engines," SAE paper 910560 presented at the 1991 International
Congress & Exposition, Detroit, MI, February 26-March 1, 1991.
8. Energy and Environmental Analysis, Inc., "Feasibility of Controlling Emissions
from Off-Road, Heavy-Duty Construction Equipment," Final report to the CARB.
Arlington, VA, May 1988.
9. Environmental Research and Technology, Inc., "Feasibility, Cost, and Air Quality
Impact of Potential Emission Control Requirements on Farm, Construction, and
Industrial Equipment in California," Document PA841, sponsored by the Farm and
3-5
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REFERENCES FOR CHAPTER 3 (Continued)
Industrial Equipment Institute, Engine Manufacturers Association, and
Construction Industry Manufacturers Association, May 1982.
10. Ingalls, M.N., "Nonroad Emission Factors," SwRI report #08-3426-005, Southwest
Research Institute for U.S. Environmental Protection Agency, February 1991.
11. Wasser, J.H., "Emulsion Fuel and Oxidation Catalyst Technology for Stationary
Diesel Engines," U.S. Environmental Protection Agency, Industrial Environmental
Research Laboratory, Research Triangle Park, NC, 1982.
12. "Standards Support and Environmental Impact Statement, Volume I: Stationary
Internal Combustion Engines," EPA-450/2-78-125a, Emission Standards and
Engineering Division, Office of Air, Noise, and Radiation, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, NC, July 1979.
13. Lips, H.I., J.A. Gotterba, and K.J. Lim, "Environmental Assessment of Combustion
Modification Controls for Stationary Internal Combustion Engines," EPA-600/7-81-
127, prepared by Acurex Corporation for Industrial Environmental Research
Laboratory, Office of Environmental Engineering and Technology, Office of Air
Quality Planning and Standards, U.S. Environmental Protection Agency, Research
Triangle Park, NC, July 1981.
14. Campbell, L.M., D.K. Stone, and G.S. Shareef, "Sourcebook: NOx Control
Technology Data," Radian for Control Technology Center, EPA-600/2-91-029,
Emission Standards Division, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, July 1991.
15. Hoggan, M., S. Cohanim, R. Sin, M. Hsu, and S. Tom, "Air Quality Trends in
California's South Coast and Southeast Desert Air Basins, 1976-1990, Air Quality
Management Plan, Appendix II-B," South Coast Air Quality Management District,
July 1991.
16. Castaldini, C., "Environmental Assessment of NOx Control on a Compression
Ignition Large Bore Reciprocating Internal Combustion Engine, Volume I:
Technical Results," EPA-600/7-86/001a, prepared by Acurex Corporation for the
Combustion Research Branch of the Energy Assessment and Control Division,
Industrial Environmental Research Laboratory, Office of Research and
Development, U.S. Environmental Protection Agency, Washington, DC, April 1984.
3-6
-------
REFERENCES FOR CHAPTER 3 (Continued)
17. Castaldini, C., and L.R. Waterland, "Environmental Assessment of a Reciprocating
Engine Retrofitted with Selective Catalytic Reduction, Volume I: Technical
Results," EPA/600/7-86/014a, prepared by Acurex Corporation for Air and Energy
Engineering Research Laboratory, Office of Research and Development, U.S.
Environmental Protection Agency, December 1984.
18. "Pooled Source Emission Test Report: Oil and Gas Production Combustion
Sources, Fresno and Ventura Counties, California," ENSR # 7230-007-700,
prepared by ENSR Consulting and Engineering for Western States Petroleum
Association (WSPA), Bakersfield, CA, December 1990.
19. Osborn, W.E., and M.D. McDannel, "Emissions of Air Toxic Species: Test
Conducted Under AB2588 for the Western States Petroleum Association," CR
72600-2061, prepared by Carnot for Western States Petroleum Association (WSPA),
Glendale, CA, May 1990.
20. Shih, C.C., J.W. Hamersma, D.G. Ackerman, et al., "Emissions Assessment of
Conventional Stationary Combustion Systems, Volume II: Internal Combustion
Sources," EPA-600/7-79-029c, prepared by TRW for Industrial Environmental
Research Laboratory, Office of Energy, Minerals, and Industry, U.S. Environmental
Protection Agency, February 1979.
21. Swenson, K.R., "Application of On-Highway Emissions Reduction Technology to an
Off-Highway Engine, Final Report Volume I," SwRI Project #03-3354-200,
prepared by Southwest Research Institute for the Santa Barbara County Air
Pollution Control District, November 1991.
22. Ingalls, M.N., "Nonroad Emission Factors of Air Toxics, Interim Report No. 2,"
SwRI report #08-3426-005, Southwest Research Institute for U.S. Environmental
Protection Agency, June 1991.
3-7
-------
4. EMISSION FACTOR DEVELOPMENT
The prior AP-42 data and the new data identified in Chapter 3 were compiled,
evaluated, and ranked using evaluation tables. The data judged as acceptable within AP-
42 criteria were then averaged, and in some cases weighted according to market share, to
produce an emission factor. All emission factors were reviewed and analyzed based on
EPA guidelines.1 The significant difference in definitions between data ranking criteria
and emission factor ranking criteria should be noted.
Definition of Emission Factor Rankings:
A - Developed only from A-rated source test data taken from many randomly
chosen facilities in the industry population. The source category is specific
enough to minimize variability within the source population.
B - Developed only from A-rated test data from a reasonable number of facilities.
Although no specific bias is evident, it is not clear if the facilities tested
represent a random sample of the industries. As with the A rating, the source is
specific enough to minimize variability within the source population.
C - Developed only from A- and B-rated test data from a reasonable number of
facilities. Although no specific bias is evident, it is not clear if the facilities
tested represent a random sample of the industry. As with the A rating, the
source category is specific enough to minimize variability within the source
population.
D - The emission factor was developed only from A- and B-rated test data from a
small number of facilities, and there may be reason to suspect that these
4-1
-------
facilities do not represent a random sample of the industry. There also may be
evidence of variability within the source population.
E - The emission factor was developed from C- and or D- rated test data, and there
may be reason to suspect that the facilities tested do not represent a random
sample of the industry. There also may be evidence of variability within the
source category population.
4.1 CRITERIA POLLUTANTS AND CARBON DIOXIDE
4.1.1 Review of Previous Data2
The quality of the data used in the previous AP-42 Chapter 3.3 revision was judged
to be of "B" quality using the current criteria specifications. The test procedures used
were similar to the Federal 13-mode tests or the EMA California 13-mode test, except for a
few that utilized 21 mode (diesel) or 23 mode (gasoline) tests. The eight diesels and four
gasoline engines ranged in size from 15 bhp to 210 bhp. The emission factors would have
been designated as "C" quality but because of the limited range of engine horsepower
tested, only a "D" rating was possible. The scope of Chapter 3.3 for diesels is up to 600
bhp, and the data cover only engines less than 210 bhp.
The major assumptions used in the prior AP-42 update to weight the pollutant test
data to develop an emission factor were:3'4
! Engine shipments as reported by the Bureau of the Census, the total value of
such shipments, and the values of the engines shipped according to power
output can be used to estimate the average power output of industrial
engines;
! A high percentage of gasoline engines classified "industrial" in the Bureau of
the Census statistics are actually in the light-duty engine category covered by
an earlier report;
! Annual usage of industrial engines is approximately one-half that of
construction engines of similar power output, and service life is 2,500 hours
for gasoline engines and 5,000 hours for diesel engines. Population of
4-2
-------
industrial engines can be estimated using the Bureau of the Census shipment
figures and the service life and annual usage estimates; and
! Engine operating cycles can be estimated by considering the type of
operation most industrial engines undergo in the field.
4.1.2 Review of New Data
References 2 and 4 through 10 contain both primary and secondary emissions data
for gasoline and diesels engines. Many of the newer references rely in part on the prior AP-
42 compilation or the data sources used for AP-42. Evaluation of the data quality for the
newer data gave a lower quality rating than for the original AP-42 data in Reference 2 due
primarily to insufficient information for the primary test engine design specifications,
operating conditions, or test methods. The prior AP-42 data were accorded a "B" rating,
whereas the new data identified in Chapter 3 were accorded a "C" or "D" rating. The
ranges of the new data were, however, in the same range as the prior AP-42 emission
factors. In view of the general agreement between the newer and prior data, and the
prohibition against mixing data of differing quality rankings, the old weighted emission
factors will be retained for criteria pollutants. Since the prior update contained data of
"B" quality, the decision was made to retain these emission factors without incorporating
the "C" and "D" quality data.
Although there are ORSAT data for C02, a calculated value based on assumptions
was used instead because it was felt that calculated values were more accurate than
ORSAT measurements. It was assumed that all of the carbon going into the engine as fuel
will appear in the exhaust as C02. The contribution of carbon to other gases [such as CO
and hydrocarbons (typically less than 0.1 percent)] is small. The emission factor for C02
will be a theoretical calculation of the carbon content of the fuel and 100 percent
conversion of C into C02. The average carbon content is 86 percent by weight for gasoline
and 87 percent by weight for diesel.
4.1.3 Compilation of Baseline Emission Factors
Table 4-1 shows a summary of the raw emissions data and their conversions for
criteria and nonorganic gaseous emissions and C02.
4-3
-------
4.1.4 Compilation of Controlled Emission Factors
Fragmentary information on control efficiencies and operational or emission side
effects of control systems is available in References 9 through 10. Insufficient data are
available to develop controlled emission factors which are representative of both engine
designs and control technologies. Chapter 5 contains a summary of qualitative information
on control applicability for the industrial engine sector.
Most of the technologies developed for on-road engines can be directly applied to
the off-road application since many engine designs are similar or identical. The actual
demonstration on the durability of these technologies with stationary application has yet to
be proven. Some on-road technologies that may be inappropriate for off-road use are:3
! High pressure turbocharging results in an engine of given horsepower rating
having poor low speed torque, but many off-road engines require good low
end torque to pull against high hydraulic loads;
! Air-to-air intercooling requires an extra heat exchanger, and heat exchange
surface fouling is common in off-road environments. Many manufacturers
believe that this technology is inappropriate in several equipment
applications;
! Electronic timing control may or may not survive in the harsh environment
of off-road use. Manufacturers are reluctant to use this technology until its
durability characteristics are well understood; and
! Particulate traps are not yet proven in an on-road environment, and
manufacturers lack information needed to evaluate traps in off-road
equipment. Concerns center around the high-load duty cycle, with possible
extended operation at full load on the "lug" line. This may aid in trap
regeneration, but trap durability may be adversely affected. The exact
nature of changes, and costs for retrofitting engines depend on the status of
each individual engine model's emission level, and the hardware changes
required to meet the changes. This varies substantially among engines and
manufacturers.
4-4
-------
4.2 TOTAL ORGANIC COMPOUNDS AND AIR TOXICS
4.2.1 Review of Old Data
The quality of the data in the previous AP-42 Chapter 3.3 revision was designated
to be of "B" quality using the current quality rating criteria. The test procedures used
were similar to the Federal 13-mode tests or the EMA California 13-mode test, except for a
few that utilized 21 mode (diesel) or 23 mode (gasoline) tests. The eight diesels and four
gasoline engines ranged in size from 15 bhp to 210 hp. A "D" rather than "C" emission
factor rating was given because the data did not span the capacity range to 600 bhp as
needed for the Chapter 3.3 source classifications. The measured data from the prior AP-42
update applicable to this section are the exhaust hydrocarbons and aldehydes. These data
were reviewed by the AP-42 evaluation criteria and were judged to remain applicable.
There was only fragmentary information available for evaporative and crankcase
hydrocarbon emissions in terms of power output (g/hp-hr) or fuel input (lb/MMBtu).
Hence, no emission factors were developed.
The major assumptions used in the prior AP-42 Chapter 3.3 to weight the engine
test data in order to arrive at an emission factor were:2
! Engine shipments as reported by the Bureau of the Census, the total value of
such shipments, and the values of the engines shipped according to power
output can be used to estimate the average power output of industrial
engines;
! A high percentage of gasoline engines classified "industrial" in the Bureau of
the Census statistics are actually in the light-duty engine category covered by
an earlier report;11
! Annual usage of industrial engines is approximately one-half that of
construction engines of similar power output, and service life is 2,500 hours
for gasoline engines and 5,000 hours for diesel engines. Population of
industrial engines can be estimated using the Bureau of the Census shipment
figures and the service life and annual usage estimates; and
4-5
-------
! Engine operating cycles can be estimated by considering the type of
operation most industrial engines undergo in the field.
4.2.2 Review of New Data
The test data were reviewed for data quality for exhaust hydrocarbons, aldehydes,
and speciated VOCs.4'5'8'11 The data quality ranking for total hydrocarbons and aldehydes
were "C" or "D" for the few data which were available. Accordingly, the emission factors
in the prior AP-42 update were retained.
New sources of "B" quality data were obtained for speciated TOC and/or air toxics
data in terms of lb/MMBtu factors6'7. The test reports did not provide the load at which
the engines were running and therefore could not be used to calculate g/hp-hr values. All
formulas and assumptions used to make conversions and calculations are presented in
Appendix A.
There is currently little information on air toxic emissions from non-road sources.
Nonroad emission factors for air toxics are inadequate and require more work. A
comprehensive study to acquire the necessary data of air toxics from representative
nonroad engines has been suggested.4 The references used in recent reports adapted data
from the old AP-42 Chapter 3.3 section and Volume II of
AP-42.2'11 This indicates some overlap in sources designated as stationary or mobile.
Factors for evaporative, crankcase, and refueling hydrocarbon emissions were based
on sparse background documentation.5 The data were therefore given a data quality rating
of "D," which results in a emission factor quality rating of "E."
4.2.3 Compilation of Emission Factors
Tables 4-2 through 4-3 summarize the raw emissions data and their conversions for
speciated organic compound and air toxic emissions.
4.3 PARTICULATE
4.3.1 Review of Old Data
As previously mentioned, the quality of the data used in the previous AP-42
Chapter 3.3 revision was determined to be "B" quality. The test procedures used were
similar to the Federal 13-mode tests or the EMA California 13-mode test, except for a few
4-6
-------
which utilized 21 mode (diesel) or 23 mode (gasoline) tests. The eight diesels and four
gasoline engines ranged in size from 15 bhp to 210 hp. An emission factor quality rating of
"D" was assigned for these tests. The test data from the prior AP-42 applicable to this
section are the particulate emissions. The prior data were evaluated by the AP-42 criteria
and judged to remain applicable.
The major assumptions used to weight the test data for use in emission factors for
this section were the same as the assumptions used to evaluate the previous TOC and air
toxics data (section 4.2 of this report).
4.3.2 Review of New Data
References 8, 5, 4 and 10 contain emissions data for diesel particulate emissions
identified in the search discussed in Chapter 3. The few new data which were identified
were in the same range as the emission factors from the prior AP-42 update. The quality of
the newer data was generally rated to be low, "C" and "D," because of the lack of detail on
the source or test procedures. In the absence of better quality data for particulate, the old
weighted emission factors were retained.
4.3.3 Compilation of Emission Factors
The data for particulate emissions are included in Table 4-1.
4-7
-------
TABLE 4-1. SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION ENGINES:
CRITERIA AND NONORGANIC GASEOUS EMISSIONS
Data Source
AB25883
EPA
SSEIS Vol. 1."
Data
Type
Units
WSPA
Water
Injection
Drilling
Rig
WSPA
Workover
Nonroad
Engines0
Nonroad
APTD-
1494
Engines'1
APTD-
1494
Engines'1
Engine
30
Engine
31
Engine
32
Engine
33
Data
Rating
B
B
B
D
B
B
C
C
C
C
Fuel6
D
D
D
D,G
D
G
D
D
D
D
Rating'
hp
350
550
350
wt % S
(Fuel)
%
0.37
0.24
0.004
%02
13.7
17.1
16.5
Exit
dscfm
743
160
F factor
dscf/MMBtu
8,915
8,902
9,194
Heat
Input
MMBtu/hr
1.72
0.19
7000
7000
7000
BSFCf
Btu/hp-hr
4914
345
HHV
Btu/lb
Btu/gal
19,500
138,450
19,500
138,450
19,972
141,800
-------
TABLE 4-1. SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION ENGINES:
CRITERIA AND NONORGANIC GASEOUS EMISSIONS (Continued)
Data Source
AB25883
EPA
SSEIS Vol. 1"
Pollutant
Units
WSPA
Water
Injectio
n
Drillin
gRig
WSPA
Workove
r Rig
Nonroad
Engines0
Nonroad
APTD-
1494
Engines'1
APTD-
1494
Engines'1
Engine
30
Engine
31
Engine
32
Engine
33
NOx
g/hp-hr
lb/MMBtu
14.0
4.41
5.16
1.63
6.60
4.60
4.00
5.50
CO
g/hp-hr
lb/lOOOgal
lb/MMBtu
1,500
0.00
691
4.87
3.03
0.95
1.99
62.67
-1.90
4.10
1.60
1.30
SOx
g/hp-hr
lb/lOOOgal
lb/MMBtu
0.85
53
0.38
0.04
34
0.25
0.931
0.29
0.268
0.084
co2
/7./mJ
ppm
g/hp-hr
lb/lOOOgal
lb/MMBtu
51,000
336.04
20,871
150.75
19,000
16.65
14,711
106.26
35,000
0.00
25,332
178.65
PM
g/hp-hr
lb/lOOOgal
lb/MMbtu
0.327
0
0.10
"Reference 6 and 7. All engines are industrial.
bReference 8. All engines are medium bore.
cReference 5. All engines are industrial.
dReference 3 (NOs, CO, SOx); Reference 2 (PM). All engines are industrial.
eD = Diesel; G = Gasoline.
'Data may be invalid.
-------
TABLE 4-2a. SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION ENGINES:
SPECIATED ORGANIC COMPOUNDS
Data Type
or
Pollutant
Units
Data Source
AB25883
EPA
SSEIS, Vol 1."
WSPA
Water
Injection
WSPA
Workover
Rig
Nonroad
Engines0
Nonroad
Engines'1
Nonroad
Engines0
Nonroad
Engines'1
Engine
30
Engine
31
Engine
32
Engine
33
Data
Rating
B
B
D
B
D
B
C
C
C
C
Fuel6
D
D
D
D
G
G
D
D
D
D
Rating'
hp
350
350
HC:
Crank
g/hp-hr
lb/MMBtu
0.02
0.01
2.20
0.69
HC:
Vapor
g/hp-hr
lb/MMBtu
0.00
0.00
0.30
0.09
HC:
Refuel
g/hp-hr
lb/MMBtu
0.00
0.00
0.49
0.15
HC: Total
Exhaust
(as CH4)
ppm
lb/hr
g/hp-hr
lb/lOOOgal
lb/MMBtu
107
0.20
0.26
16
0.117
67.8
16
0.115
1.12
0.35
6.68
2.10
6.60
0.60
0.30
0.20
Aldehydes
g/hp-hr
lb/MMBtu
0.21
0.07
0.22
0.07
-------
TABLE 4-2b. SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION
ENGINES: SPECIATED ORGANIC COMPOUNDS
Data Type
Units
AB25883
or Pollutant
WSPA Water Injection
WSPA Workover Rig
Benzene
ppm
0.147
PPb
95
lb/hr
9.77E-04
g/hp-hr
1.19E-03
lb/lOOOgal
0.0742
0.1880
lb/MMBtu
5.36E-04
1.33E-03
Toluene
ppm
0.050
PPb
40
lb/hr
4.81E-04
g/hp-hr
5.86E-04
lb/lOOOgal
0.0364
0.0789
lb/MMBtu
2.63E-04
5.56E-04
Xylenes
ppm
0.021
PPb
41
lb/hr
5.68E-04
g/hp-hr
6.93E-04
lb/lOOOgal
0.0431
0.0366
lb/MMBtu
3.11E-04
2.58E-04
Propylene
ppm
0.793
PPb
430
lb/hp-hr
2.38E-03
g/hp-hr
2.90E-03
lb/lOOOgal
0.1800
0.5477
lb/MMBtu
1.30E-03
3.86E-03
1,3 Butadiene
PPb
<10
g/hp-hr
<8.72E-05
lb/lOOOgal
<7.12E-05
lb/MMBtu
<3.91E-05
Formaldehyde
Mg/m3
821
ppm
0.284
PPb
647
lb/hr
2.26E-03
g/hp-hr
3.08E-03
lb/lOOOgal
0.1911
0.1400
lb/MMBtu
1.38E-03
9.87E-04
4-11
-------
TABLE 4-2b. SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL COMBUSTION
ENGINES: SPECIATED ORGANIC COMPOUNDS (Continued)
Data Type
Units
AB25883
or Pollutant
WSPA Water Injection
WSPA Workover Rig
Acetaldehyde
Mg/m3
632
ppm
0.091
PPb
340
lb/hr
1.74E-03
g/hp-hr
2.39E-03
lb/lOOOgal
0.1481
0.0658
lb/MMBtu
1.07E-03
4.64E-04
Acrolein
Mg/m3
<31
ppm
0.020
PPb
<13
lb/hr
<8.60E-05
g/hp-hr
<1.18E-04
lb/lOOOgal
<0.0073
0.0187
lb/MMBtu
<5.30E-05
1.32E-04
"•Reference 6 and 7.
4-12
-------
TABLE 4-3. SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL
COMBUSTION ENGINES: AIR TOXICS
Data Type
or Pollutant
Units
AB2588
WSPA
Water Injection3
WSPA
Workover Rigb
Data Rating
B B
Fuel
D D
Rating
hp
350 350
Naphthalene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
31.8 41.90
8.84E-05
0.0166
5.25E-05 1.17E-04
Acenaphthylene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
<0.006 3.61
<1.75E-08
0.0014
<1.03E-08 1.01E-05
Acenaphthene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
<0.006 1.01
<1.75E-08
0.0004
<1.03E-08 2.83E-06
Flourene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
31.9 2.17
8.84E-05
0.0009
5.24E-05 6.04E-06
Phenanthrene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
27.7 4.77
7.68E-05
0.0019
4.55E-05 1.33E-05
Anthracene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
1.4 0.51
3.89E-06
0.0002
2.30E-06 1.43E-06
Flouranthene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
7.8 0.90
2.17E-05
0.0004
1.27E-05 2.51E-06
Pyrene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
3.3 1.51
9.09E-06
0.0006
5.35E-06 4.22E-06
4-13
-------
TABLE 4-3. SUMMARY OF EMISSIONS DATA FOR STATIONARY INTERNAL
COMBUSTION ENGINES: AIR TOXICS (Continued)
Data Type
or Pollutant
Units
AB2588
WSPA
Water Injection3
WSPA
Workover Rigb
Benz(a)anthracene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
1.7 0.24
4.60E-06
0.0001
2.69E-06 6.62E-07
Chrysene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
0.27 0.09
7.52E-07
0.00004
4.45E-07 2.61E-07
Benzo(b)fluoranthene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
<0.006 0.07
<1.65E-08
0.00003
<1.03E-08 1.88E-07
Benzo(k)fluoranthene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
<0.006 0.11
<1.75E-08
0.00004
<1.03E-08 3.00E-07
Benzo(a)pyrene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
<0.006 <0.13
<1.75E-08
<0.00005
<1.03E-08 <3.65E-07
Ideno(l,2,3-cd)pyrene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
0.17 <0.17
4.63E-07
<0.0001
2.74E-08 <4.75E-07
Dibenz(a,h)anthracene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
0.25 <0.27
7.02E-07
<0.0001
4.14E-07 7.51E-07
Benzo(g,h,l)perylene
Mg/m3
lb/hr
lb/lOOOgal
lb/MMBtu
0.25 <0.20
7.06E-07
<0.0001
4.16E-07 <5.61E-07
"Reference 6.
bReference 7.
4-14
-------
REFERENCES FOR CHAPTER 4
1. Technical Procedures for Developing AP-42 Emission Factors and Preparing AP-42
Sections (Draft), Emission Inventory Branch, Technical Support Division, Office of
Air and Radiation, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, March 6,1992.
2. Hare, C.T. and K.J. Springer, "Exhaust Emissions from Uncontrolled Vehicles and
Related Equipment Using Internal Combustion Engines, Final Report, Part 5:
Heavy-Duty Farm, Construction, and Industrial Engines," under Contract No. EHS
70-108, Publication #APTD-1494, prepared by Southwest Research Institute (San
Antonio, Texas), for U.S. Environmental Protection Agency, Research Triangle
Park, NC, October 1973.
3. "Compilation of Air Pollutant Emission Factors, Volume II," EPA Report No. AP-
42, Fourth Edition, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, September 1985.
4. Hare, C.T. and K.J. Springer, "Exhaust from Uncontrolled Vehicles and Related
Equipment Using Internal Combustion Engines, Final Report Part 4: Small Air-
Cooled Spark Ignition Utility Engines," Publication #APTD-1493, prepared by
Southwest Research Institute, for U.S. Environmental Protection Agency, Ann
Arbor, MI, May 1973.
5. "Nonroad Engine and Vehicle Emission Study-Report," EPA-460/3-91-02,
Certification Division, Office of Mobile Sources, Office of Air & Radiation, U.S
Environmental Protection Agency, November 1991.
6. Osborn, W. E., and M. D. McDannel, "Emissions of Air Toxic Species: Test
Conducted Under AB2588 for the Western States Petroleum Association,"
CR 72600-2061, prepared by Carnot for Western States Petroleum Association
(WSPA), Glendale, CA, May 1990.
7. "Pooled Source Emission Test Report: Oil and Gas Production Combustion
Sources, Fresno and Ventura Counties, California," ENSR #7230-007-700,
prepared by ENSR Consulting and Engineering for Western States Petroleum
Association (WSPA), Bakersfield, CA, December, 1990.
8. "Standards Support and Environmental Impact Statement, Volume I: Stationary
Internal Combustion Engines," EPA-450/2-78-125a, Emission Standards and
Engineering Division, Office of Air, Noise, and Radiation, Office of Air Quality
4-15
-------
Planning and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, NC, July 1979.
9. Wasser, J.H., "Emulsion Fuel and Oxidation Catalyst Technology for Stationary
Diesel Engines," U.S. Environmental Protection Agency, Industrial Environmental
Research Laboratory, Research Triangle Park, NC, 1982.
10. Lips, H.I., J.A. Gotterba, and K.J. Lim, "Environmental Assessment of Combustion
Modification Controls for Stationary Internal Combustion Engines," EPA-600/7-
81-127, Industrial Environmental Research Laboratory, Office of Environmental
Engineering and Technology, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, July 1981.
11. "Feasibility of Controlling Emissions from Off-Road, Heavy-Duty Construction
Equipment," Final Report, prepared by Energy and Environment Analysis for the
California Air Resources Board, El Monte, CA, December 1988.
4-16
-------
5. AP-42 SECTION 3.3: GASOLINE AND DIESEL INDUSTRIAL ENGINES
The revision to Section 3.3 of AP-42 is presented in the following pages as it would
appear in the document.
5-1
-------
3.3 GASOLINE AND DIESEL INDUSTRIAL ENGINES
3.3.1 General
The engine category addressed by this section covers a wide variety of industrial applications
of both gasoline and diesel internal combustion engines such as, aerial lifts, fork lifts, mobile
refrigeration units, generators, pumps, industrial sweepers/scrubbers, material handling equipment
(such as conveyors), and portable well-drilling equipment. The rated power of these engines covers a
rather substantial range; up to 186 kW (250 hp) for gasoline engines and up to 447 kW (600 hp) for
diesel engines. (Diesel engines greater than 600 hp are covered in Section 3.4: Large Stationary
Diesel and All Stationary Dual Fuel Engines). Understandably, substantial differences in engine duty
cycles exist. It was necessary, therefore, to make reasonable assumptions concerning usage in order
to formulate some of the emission factors.
3.3.2 Process Description
All reciprocating internal combustion (IC) engines operate by the same basic process. A
combustible mixture is first compressed in a small volume between the head of a piston and its
surrounding cylinder. The mixture is then ignited, and the resulting high pressure products of
combustion push the piston through the cylinder. This movement is converted from linear to rotary
motion by a crankshaft. The piston returns, pushing out exhaust gases, and the cycle is repeated.
There are two methods used for stationary reciprocating IC engines: compression ignition
(CI) and spark ignition (SI). Section 3.3 deals with both types of reciprocating internal combustion
engines.
In compression ignition engines, combustion air is first compression heated in the cylinder,
and diesel fuel oil is then injected into the hot air. Ignition is spontaneous as the air is above the auto-
ignition temperature of the fuel. Spark ignition engines initiate combustion by the spark of an
electrical discharge. Usually the fuel is mixed with the air in a carburetor (for gasoline) or at the
intake valve (for natural gas), but occasionally the fuel is injected into the compressed air in the
cylinder. All diesel fueled engines are compression ignited and all gasoline fueled engines are spark
ignited.
CI engines usually operate at a higher compression ratio (ratio of cylinder volume when the
piston is at the bottom of its stroke to the volume when it is at the top) than SI engines because fuel is
not present during compression; hence there is no danger of premature auto-ignition. Since engine
thermal efficiency rises with increasing pressure ratio (and pressure ratio varies directly with
compression ratio), CI engines are more efficient than SI engines. This increased efficiency is gained
at the expense of poorer response to load changes and a heavier structure to withstand the higher
pressures.
3.3.3 Emissions and Controls
The best method for calculating emissions is on the basis of "brake specific" emission factors
(g/hp-hr or g/kW-hr). Emissions are calculated by taking the product of the brake specific emission
4/93
Stationary Internal Combustion Sources
3.3-1
-------
factor, the usage in hours (that is, hours per year or hours per day), the power available (rated
power), and the load factor (the power actually used divided by the power available).
Once reasonable usage and duty cycles for this category were ascertained, emission values
were aggregated to arrive at the factors presented in Tables 3.3-1 (English units) and 3.3-2 (Metric
units) for criteria and organic pollutants. Emissions data for a specific design type were weighted
according to estimated material share for industrial engines. The emission factors in this table are
most appropriately applied to a population of industrial engines rather than to an individual power
plant because of their aggregate nature. Table 3.3-3 shows unweighted speciated organic compound
and air toxic emissions factors based upon only two engines. Their inclusion in this section is
intended only for rough order of magnitude estimates.
Table 3.3-4 shows a summary of various diesel emission reduction technologies (some which
may be applicable to gasoline engines). These technologies are categorized into fuel modifications,
engine modifications, and exhaust after treatments. Current data are insufficient to quantify the
results of the modifications. Table 3.3-4 provides general information on the trends of changes on
selected parameters.
3.3-2
4/93
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TABLE 3.3-1. (ENGLISH UNITS) EMISSION FACTORS FOR UNCONTROLLED GASOLINE
AND DIESEL INDUSTRIAL ENGINES3
(Source Classification Codes)
Pollutant
Gasoline Fuel
(SCC 20200301, 20300301)
Diesel Fuel
(SCC 20200102, 20300101)
[Rating]b
[grams/hp-hr]
(power output)
[lb/MMBtu]
(fuel input)
[grams/hp-hr]
(power output)
[lb/MMBtu]
(fuel input)
NOx [D]
5.16
1.63
14.0
4.41
CO [D]
199
62.7
3.03
0.95
SOx [D]
0.268
0.084
0.931
0.29
Particulate [D]
0.327
0.10
1.00
0.31
C02 [B]c
493
155
525
165
Aldehydes [D]
0.22
0.07
0.21
0.07
Hydrocarbons
Exhaust [D]
6.68
2.10
1.12
0.35
Evaporative [E]
0.30
0.09
0.00
0.00
Crankcase [E]
2.20
0.69
0.02
0.01
Refueling [El
0.49
0.15
0.00
0.00
"Data based on uncontrolled levels for each fuel from References 1, 3 and 6.
When necessary, the average brake specific fuel consumption (BSFC) value was
used to convert from g/hp-hr to lb/MMBtu was 7000 Btu/hp-hr.
b"D" and "E" rated emission factors are most appropriate when applied to a
population of industrial engines rather than to an individual power plant, due
to the aggregate nature of the emissions data.
cBased on assumed 100 percent conversion of carbon in fuel to C02 with 87 weight
percent carbon in diesel, 86 weight percent carbon in gasoline, average brake
specific fuel consumption of 7000 Btu/hp-hr, diesel heating value of 19300 Btu/lb,
and gasoline heating value of 20300 Btu/lb.
4/93
Stationary Internal Combustion Sources
3.3-3
-------
TABLE 3.3-2. (METRIC UNITS) EMISSION FACTORS FOR UNCONTROLLED GASOLINE
AND DIESEL INDUSTRIAL ENGINES3
(Source Classification Codes)
Pollutant
Gasoline Fuel
(SCC 20200301, 20300301)
Diesel Fuel
(SCC 20200102, 20300101)
[Rating]b
[grams/kW-hr]
(power output)
[ng/J]
(fuel input)
[grams/kW-hr]
(power output)
[ng/J]
(fuel input)
NOx [D]
6.92
699
18.8
1,896
CO [D]
267
26,947
4.06
410
SOx [D]
0.359
36
1.25
126
Particulate [D]
0.439
44
1.34
135
C02 [B]c
661
66,787
704
71,065
Aldehydes [D]
0.30
29
0.28
28
Hydrocarbons
Exhaust [D]
8.96
905
1.50
152
Evaporative [E]
0.40
41
0.00
0.00
Crankcase [E]
2.95
298
0.03
2.71
Refueling [El
0.66
66
0.00
0.00
"Data based on uncontrolled levels for each fuel from References 1, 3 and 6.
b"D" and "E" rated emission factors are most appropriate when applied to a
population of industrial engines rather than to an individual power plant,
due to the aggregate nature of the emissions data.
cBased on assumed 100 percent conversion of carbon in fuel to C02 with 87 weight
percent carbon in diesel, 86 weight percent carbon in gasoline, average brake
specific fuel consumption of 7000 Btu/hp-hr, diesel heating value of 19300 Btu/lb,
and gasoline heating value of 20300 Btu/lb.
3.3-4
4/93
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TABLE 3.3-3. (ENGLISH AND METRIC UNITS) SPECIATED ORGANIC COMPOUNDS AND
AIR TOXIC EMISSION FACTORS FOR UNCONTROLLED DIESEL ENGINES3
(Source Classification Codes: 20200102, 20300101)
(ALL EMISSION FACTORS ARE RATED: E)b
Pollutant
[lb/MMBtu]
[ng/J]
(fuel input)
(fuel input)
Benzene
9.33 E-04
0.401
Toluene
4.09 E-04
0.176
Xylenes
2.85 E-04
0.122
Propylene
2.58 E-03
1.109
1,3 Butadiene0
< 3.91 E-05
< 0.017
Formaldehyde
1.18 E-03
0.509
Acetaldehyde
7.67 E-04
0.330
Acrolein
< 9.25 E-05
< 0.040
Polycyclic Aromatic Hydrocarbons (PAH)
Naphthalene
8.48 E-05
3.64 E-02
Acenaphthylene
< 5.06 E-06
< 2.17 E-03
Acenaphthene
< 1.42 E-06
<6.11 E-04
Fluorene
2.92 E-05
1.26 E-02
Phenanthrene
2.94 E-05
1.26 E-02
Anthracene
1.87 E-06
8.02 E-04
Fluoranthene
7.61 E-06
3.27 E-03
Pyrene
4.78 E-06
2.06 E-03
Benz(a)anthracene
1.68 E-06
7.21 E-04
Chrysene
3.53 E-07
1.52 E-04
Benzo(b)fluoranthene
< 9.91 E-08
< 4.26 E-05
Benzo(k)fluoranthene
< 1.55 E-07
< 6.67 E-05
Benzo(a)pyrene
< 1.88 E-07
< 8.07 E-05
Indeno(l,2,3-cd)pyrene
< 3.75 E-07
< 1.61 E-04
Dibenz(a,h)anthracene
< 5.83 E-07
< 2.50 E-04
Benzo(g,h,l)perylene
< 4.89 E-07
< 2.10 E-04
Total PAH
1.68 E-04
7.22 E-02
aData are based on the uncontrolled levels of two diesel engines from References 6 and 7.
b"E" rated emission factors are due to limited data sets, inherent variability in the
population and/or a lack of documentation of test results. "E" rated emission factors
may not be suitable for specific facilities or populations and should be used with care.
cData are based on one engine.
4/93
Stationary Internal Combustion Sources
3.3-5
-------
TABLE 3.3-4. DIESEL EMISSION CONTROL TECHNOLOGIES3
Technology
Affected Parameterb
Increase
Decrease
Fuel Modifications
Sulfur Content Increase
PM, Wear
Aromatic Content Increase
PM, NOx
Cetane Number
PM, NOx
10 percent and 90 percent Boiling Point
PM
Fuel Additives
PM, NOx
Water/Fuel Emulsions
NOx
Engine Modifications
Injection Timing
NOx, PM, BSFC,
Power
NOx
Fuel Injection Pressure
PM, NOx
Injection Rate Control
NOx, PM
Rapid Spill Nozzles
PM
Electronic Timing & Metering
NOx, PM
Injector Nozzle Geometry
PM
Combustion Chamber Modifications
NOx, PM
Turbocharging
PM, Power
NOx
Charge Cooling
NOx
Exhaust Gas Recirculation
PM, Power, Wear
NOx
Oil Consumption Control
Exhaust After Treatment
Particulate Traps
Selective Catalytic Reduction
Oxidation Catalysts
PM, Wear
PM
NOx
HC, CO, PM
"Reference 4.
bNOx = Nitrogen oxides; PM = Particulate matter; HC = Hydrocarbons;
CO = Carbon monoxide; BSFC = Brake specific fuel consumption.
3.3-6
4/93
-------
References for Section 3.3
1. Hare, C.T. and K.J. Springer, Exhaust Emissions from Uncontrolled Vehicles and Related
Equipment using Internal Combustion Engines. Part 5: Farm. Construction, and Industrial
Engines. U.S. Environmental Protection Agency, Research Triangle Park, NC, Publication
APTD-1494, October 1973, pp. 96-101.
2. Lips, H.I., J.A. Gotterba, and K.J. Lim, Environmental Assessment of Combustion
Modification Controls for Stationary Internal Combustion Engines. EPA-600/7-81-127,
Industrial Environmental Research Laboratory, Office of Environmental Engineering and
Technology, Office of Air Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, NC, July 1981.
3. Standards Support and Environmental Impact Statement. Volume I: Stationary Internal
Combustion Engines. EPA-450/2-78-125a, Emission Standards and Engineering Division,
Office of Air, Noise, and Radiation, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC, July 1979.
4. Technical Feasibility of Reducing NO. and Particulate Emissions from Heaw-Dutv Engines.
Draft Report by Acurex Environmental Corporation for the California Air Resources Board,
Sacramento, CA, March 1992, CARB Contract A132-085.
5. Nonroad Engine and Vehicle Emission Study-Report. EPA-460/3-91-02, Certification
Division, Office of Mobile Sources, Office of Air & Radiation, U.S. Environmental Protection
Agency, Research Triangle Park, NC, November 1991.
6. Pooled Source Emission Test Report: Oil and Gas Production Combustion Sources. Fresno
and Ventura Counties. California. Report prepared by ENSR Consulting and Engineering
for Western States Petroleum Association (WSPA), Bakersfield, CA, December 1990, ENSR
7230-007-700.
7. Osborn, W.E., and M.D. McDannel, Emissions of Air Toxic Species: Test Conducted Under
AB2588 for the Western States Petroleum Association. Report prepared by Carnot for
Western States Petroleum Association (WSPA), Glendale, CA, May 1990, CR 72600-2061.
4/93
Stationary Internal Combustion Sources
3.3-7
-------
APPENDIX A
SAMPLE CALCULATIONS
-------
Convention used:
1/hp/hr = 1/hp-hr
Assumptions: If needed (see Appendix E):
Heating value of diesel is 19300 Btu/lb
Heating value of gasoline is 20300 Btu/lb
Density of diesel is 7.1 lb/gal
Weight percent of carbon in diesel is 87percent
Weight percent of carbon in gasoline is 86percent
Average brake specific fuel consumption (BSFC) = 7000 Btu/hp-hr
To convert from heat input (MMBtu/hr) to BSFC (Btu/hp-hr)
Assumptions: Engine is running at full load (in hp)
(heat input)*(l/(engine rating in hp)) = BSFC
(MMBtu/hr)*(1000000 Btu/MMBtu)*(l/hp) = Btu/hp/hr = Btu/hp-hr
To convert from g/hp-hr to lb/MMBtu
Assumptions: You have BSFC (Btu/hp-hr)
(g/hp-hr)*(l/(Btu/hp-hr))*(l lb/453.6 g)*(1000000 Btu/MMBtu) = lb/MMBtu
To calculate heating value (Btu/lb) from BSFC (lb/hp-hr) and fuel rate (Btu/hp-hr)
(Btu/hp-hr)*(l/(lb/hp-hr)) = Btu/lb
To convert heating values of Btu/lb to Btu/gal and visa versa
Assumptions: Density = 7.1 lb/gal
(Btu/lb) *(7.1 lb/gal) = Btu/gal
(Btu/gal)/(7.1 lb/gal) = Btu/lb
To convert from g/hp-hr to lb/MMBtu
Assumptions: You have the heat input value (MMBtu/hr)
Engine is running at full load (in hp)
(g/hp-hr)*(l/(MMBtu/hr))*(hp)*(l lb/453.6 g) = lb/MMBtu
A-2
-------
To convert from g/hp-hr to lb/Mgal (where Mgal = 1000 gal)
Assumptions: You have BSFC (Btu/hp-hr) and heating value (Btu/gal)
(g/hp-hr)*(l/(Btu/hp-hr))*(l lb/453.6 g)*(Btu/gal)*(1000 gal/Mgal) = lb/Mgal
To convert from lb/MMBtu to lb/Mgal
Assumptions: You have the heating value (Btu/gal)
(lb/MMBtu)*(l MMBtu/1000000 Btu)*(Btu/gal)*(1000 gal/Mgal) = lb/Mgal
To convert from lb/MMBtu to g/hp-hr
Assumptions: You have the BSFC value (Btu/hp-hr)
(lb/MMBtu)*(l MMBtu/1000000 Btu)*(453.6 g/lb)*(Btu/hp-hr) = g/hp-hr
To convert % by volume to ppmv
% = parts per 100, therefore
(%/100)*(1000000/1000000) = (%*10000)/1000000 = %* 10000 ppmv
e.g., 5.1% CO = 51000 ppmv
To convert jig/s to g/hp-hr
Assumptions: Engine is running at full load (in hp)
(jig/s)*(l g/1000000 jig)*(3600 s/hr)*(l/hp) = g/hp-hr
To convert from ppm of a gas to lbm/MMBtu:
Assumptions: You have the molecular weight of the gas (in lb/lb-mol)
The concentration of the gas (in ppm)
You know the fuel F-factor (ft3/MMBtu)
You know the percent 02 level
At STP conditions (293 K and 1 atm), 1 mole of gas occupies 385.3 ft3/lb-mol
(ppm/1000000)/(385.3 ft3/! b-mol)*(lb/lb-mol)*(ft3/MMBtu)*(20.9/(20.9-%02))= lb/MMBtu
A-3
-------
To convert from g/hp-hr (english units) to g/kW-hr (metric units):
(g/hp-hr)*(1.341 hp-hr/kW-hr) = g/kW-hr
To convert from lb/MMBtu (english units) to ng/J (metric units):
(lb/MMBtu)*(453.6 g/lb)*(l MMBtu/1000000 Btu)*(l Btu/1055 J)*(1000000000 ng/g) =
ng/J
To calculate C02 emissions for diesel and gasoline from weight percent of carbon and BSFC
(g/hp-hr):
Assumptions: 87 wt% carbon in diesel
76 wt% carbon in gasoline
Diesel heating value = 19300 Btu/lb
Gasoline heating value = 20300 Btu/lb
BSFC = 7000 Btu/hp-hr
For diesel fuel
(87 lbC/100 lbFuel)*(l lb-molC/12 lbC)*(l lb-molC02/lb-molC)*
(44 lbC02/lb-molC02)*(lbFuel/19300 Btu)*(1000000 Btu/MMBtu) = 165 lb/MMBtu
and
(165 lbC02/MMBtu)*(l MMBtu/1000000 Btu)*(453.6 g/lb)*(7000 Btu/hp-hr) = 524 g/hp-
hr
For gasoline fuel
(86 lbC/100 lbFuel)*(l lb-molC/12 lbC)*(l lb-molC02/lb-molC)*
(44 lbC02/lb-molC02)*(lbFuel/20300 Btu)*(1000000 Btu/MMBtu) = 155.3 lb/MMBtu
and
(155.3 lbC02/MMBtu)*(l MMBtu/1000000 Btu)*(453.6 g/lb)*(7000 Btu/hp-hr) = 493 g/hp-
hr
A-4
-------
APPENDIX B
SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE
-------
TABLE B-l SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE
COMPANY/AGENCY
CONTACT PERSON
KANSAS DEPT. OF HEALTH AND ENVIRONMENT
HARISH AGARWAL,
MR HINTHER
MANUFACTURERS OF EMISSION CONTROLS ASSOCIATION (MECA)
CAROLYN
GILLESPIE,
RAYMOND CONNOR
EPA OFFICE OF MOBILE SOURCES, ANN ARBOR, MI
GREGJANSSEN,
KEVIN GREEN
AMERICAN PETROLEUM INSTITUTE (API)
JIM WILLIAMS
INDUSTRIAL GAS CLEANING INSTITUTE (IGCI)
JEFF SMITH
MONTEREY BAY AIR POLLUTION CONTROL DISTRICT
LARRY BORELLI
SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT (SCAQMD)
BILL DENNISON
ENGINE MANUFACTURERS ASSOCIATION (EMA)
GLENN KELLER
AMERICAN HONDA
VIA EMA
AMERICAN SUZUKI MOTOR CORPORATION
VIA EMA
BRIGGS & STRATTON CORPORATION
VIA EMA
CATERPILLAR INC.
DON DOWDALL
CUMMINS ENGINE COMPANY
MIKE BRAND
DEERE & COMPANY
VIA EMA
DETROIT DIESEL CORPORATION
VIA EMA
DEUTZ CORPORATION
VIA EMA
FORD NEW HOLLAND
VIA EMA
FORD POWER PRODUCTS DIVISION
VIA EMA
GENERAL ELECTRIC
VIA EMA
GENERAL MOTORS CORPORATION
VIA EMA
ISUZU MOTORS AMERICA, INC.
VIA EMA
KAWASAKI MOTORS CORP.
VIA EMA
KOHLER COMPANY
VIA EMA
KOMATSU LTD.
VIA EMA
KUBOTA CORPORATION
VIA EMA
LISTER-PETTER, INC.
VIA EMA
MITSUBISHI ENGINE NORTH AMERICA, INC.
VIA EMA
ONAN CORPORATION
VIA EMA
TECUMSEH PRODUCTS COMPANY
VIA EMA
TELEDYNE TOTAL POWER
VIA EMA
YANMAR DIESEL AMERICA
VIA EMA
COOPER AJAX/SUPERIOR DIVISION
BRUCE CHRISMANN
TEXAS AIR CONTROL BOARD
RANDY HAMILTON
B-2
-------
TABLE B-l SUMMARY OF COMMUNICATIONS ATTEMPTED/MADE (Continued)
COMPANY/AGENCY
CONTACT PERSON
UTAH AIR QUALITY BOARD
DON ROBINSON,
NORMAN ERICKSON
WAUKESHA
PAUL CANNESTRA
FLORIDA DEPARTMENT OF ENVIRONMENTAL REGULATIONS
CLAIR FANCY
COOPER BESSEMER
BILL HEATER
BAY AREA AIR QUALITY MANAGEMENT DISTRICT
STEVE HILL,
BOB NISHIMURA,
MARK NASH
KANSAS EPA, AIR TOXICS DIVISION
ED BUCKNER
NEW YORK EPA
FRANK JON
FAIRBANKS MORSE ENGINE DIVISION
PAUL DANYLUK
MISSOURI NATURAL RESOURCE AIR POLLUTION CONTROL
TODD CRAWFORD
PROGRAM
DIESEL ENGINE MANUFACTURERS ASSOCIATION (DEMA)
VENTURA COUNTY AIR POLLUTION CONTROL DISTRICT
TERRI THOMAS
WESTERN STATES PETROLEUM ASSOCIATION (WSPA)
MIKE EMANUEL
FRESNO COUNTY AIR POLLUTION CONTROL DISTRICT
ROBERT DOWELL
NORTH COAST UNIFIED AIR QUALITY MANAGEMENT DIST.
BOB CLARK
SACRAMENTO METROPOLITAN AIR QUALITY MANAGEMENT
BRUCE NIXON
DISTRICT
SAN JOAQUIN COUNTY AIR POLLUTION CONTROL DISTRICT
LAKHMIR GREWAL
CALAVERAS COUNTY AIR POLLUTION CONTROL DISTRICT
ROBERT MARSHALL
LAKE COUNTY AIR QUALITY MANAGEMENT DISTRICT
ROBERT REYNOLDS
LASSEN COUNTY AIR POLLUTION CONTROL DISTRICT
KENNETH SMITH
B-3
-------
APPENDIX C
MARKED-UP PREVIOUS AP-42 SECTION
-------
1. Lips, H. I., J. A. Gotterba, and K. J. Lim, Environmental
Assessment of Combustion Modification Controls for
Stationary Internal Combustion Engines, Report prepared by
Acurex Corporation for Industrial Environmental Research
Laboratory, Office of Environmental Engineering and
Technology, Office of Air Quality Planning and Standards,
EPA, Research Triangle Park, NC, July 1981, EPA-600/7-81-
127 .
2. Standards Support and Environmental Impact Statement, Volume
I: Stationary Internal Combustion Engines, Emission
Standards and Engineering Division, Office of Air, Noise,
and Radiation, Office of Air Quality Planning and Standards,
EPA, Research Triangle Park, NC, July 1979, EPA-450/2-7 8-
125a.
3. Nonroad Engine and Vehicle Emission Study-Report,
Certification Division, Office of Mobile Sources, Office of
Air & Radiation, EPA, November 1991, EPA-460/3-91-02.
4. Lips, H. I., et al., Reference 1, pp. 3-1 to 3-7.
5. Arcoumanis, C., editor, Internal Combustion Engines,
Academic Press, San Diego, 1988
C-2
4/93
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