U.S. Environmental Protection Agency Industrial Environmental Research EPA-600/7-78-046
Office of Research and Development Laboratory +r\^o
Research Triangle Park. North Carolina 27711 MatCn 1978
ENVIRONMENTAL ASSESSMENT
OF STATIONARY SOURCE
NOX CONTROL TECHNOLOGIES:
First Annual Report
Interagency
Energy-Environment
Research and Development
Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide-range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield. Virginia 22161.
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EPA-600/7-78-046
March 1978
ENVIRONMENTAL ASSESSMENT
OF STATIONARY SOURCE
NOX CONTROL TECHNOLOGIES:
First Annual Report
by
L R. Waterland, H. B. Mason, R. M. Evans,
K. G. Salvesen, and K. J. Wolfe
Acurex Corporation/Aerotherm Division
485 Clyde Avenue
Mountain View, California 94042
Contract No. 68-02-2160
Program Element No. EHE624A
EPA Project Officer: Joshua S. Bowen
Industrial Environmental Research Laboratory
Office of Energy, Minerals and Industry
Research Triangle Park, N.C. 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, D.C. 20460
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TABLE OF CONTENTS
Section Page
1 INTRODUCTION 1
1.1 Background 1
1.2 Program Overview 3
2 CURRENT PROCESS TECHNOLOGY 7
2.1 Utility Boilers 9
2.2 Packaged Boilers 12
2.3 Warm Air Furnaces and Other Commercial and
Residential Combustion Equipment 13
2.4 Gas Turbines 13
2.5 Stationary Reciprocating 1C Engines 14
2.6 Industrial Process Heating 15
2.7 Summary 15
3 CURRENT ENVIRONMENTAL BACKGROUND 19
3.1 Multimedia Environmental Goals Data Requirements 20
3.2 Research Methods 21
3.2.1 Methods to Assess Ambient Pollutant Health
Effects 21
3.2.2 Methods of Assessing Pollutant Impacts on
Biota 22
3.3 Concentration Estimates for Screening Combustion-
Related Pollutants 23
3.4 Summary and Conclusions 23
4 ENVIRONMENTAL OBJECTIVES DEVELOPMENT 25
4.1 Impact Assessment Procedures 26
4.2 Source Analysis Model 28
4.2.1 Air Impact 28
4.2.2 Liquid and Solid Waste Impacts 30
4.3 Assessment of Incremental Impacts Due to NOX
Controls 30
4.4 Systems Analysis Methods 32
4.4.1 Model Development 33
4.4.2 Model Application 35
m
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TABLE OF CONTENTS (Concluded)
Section Page
5 CONTROL TECHNOLOGY BACKGROUND 41
5.1 Status and Prospects of Control Requirements . . 41
5.2 Combustion Process Modification Technology ... 42
5.3 Alternate Control Techniques 45
5.4 Overall Evaluation and Conclusions 46
6 CONTROL TECHNOLOGY ASSESSMENT 51
6.1 Process Engineering Approach 51
6.2 Process Engineering Methodology 52
7 ENVIRONMENTAL DATA ACQUISITION 57
7.1 Baseline Emissions Inventory 57
7.2 Incremental Emissions Due to NOX Controls .... 63
7.3 Test Program Development 69
8 ENVIRONMENTAL ALTERNATIVES ANALYSIS 77
8.1 Evaluation of NOX Control Requirements - 78
8.2 Source/Control Priorities 85
8.3 Pollutant/Impact Screening 89
9 TECHNOLOGY TRANSFER 99
10 FUTURE EFFORTS 101
REFERENCES 103
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LIST OF ILLUSTRATIONS
Figure Page
1-1 NOX E/A approach 5
2-1 Sources of nitrogen oxide emissions 8
4-1 Impact assessment procedure 27
4-2 Elements of the systems analysis model 34
6-1 Process engineering ~ subtask flowsheet 53
7-1 Distribution of stationary anthropogenic NOX emissions
for the year 1974 (stationary fuel combustion:
controlled NOX levels) 59
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LIST OF TABLES
Table Page
2-1 Sifhif leant Stationary Fuel Combustion Equipment
Types/Major Fuels .................. 10
2-2 Summary of Source Characterization ......... 16
4-1 Air Pollution Characteristics of the NOX Impacted
AQCRs and AQMAs ................... 37
4-2 Characteristic Groups of NOX Impacted AQCRs and
AQMAs ........................ 38
5-1 Summary of NOX Control Technology .......... 47
7-1 1974 Summary of Air and Solid Pollutant Emission
from Stationary Fuel Burning Equipment (1,000 Mg) . . 60
7-2 NOX Mass Emission Ranking of Stationary Combustion
Equipment and Criteria Pollutant and Fuel Use Cross
Ranking ....................... 61
7-3 Evaluation of Incremental Emissions Due to NOX
Controls Applied to Boilers ............. 65
7-4 Evaluation of Incremental Emissions Due to NOX
Controls Applied to 1C Engines ........... 66
7-5 Evaluation of Incremental Emissions Due to NOX
Controls Applied to Gas Turbines .......... 67
7-6 Sample Test Matrix ~ Vapor Phase Constituents ... 71
7-7 Sample Test Matrix ~ Condensed Phase
Constituents .................... 73
8-1 Summary of Control Levels Required to Meet
Standard in Los Angeles, AQCR 024 ......... 79
8-2 Control Prioritization for Los Angeles ....... 81
8-3 Summary of Control Levels Required to Meet
Standard in Chicago, AQCR 067 ........... 82
8-4 Control Prioritization for Chicago ......... 83
8-5 Evaluation of Source Priorities .......... 87
VI
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LIST OF TABLES (Concluded)
Table
8-6
8-7
8-8
8-9
Summary of Source Control Priorities
Comparison of Pollutant Emission Levels with NOX
Controls to Maximum Allowable Emissions
Comparison of Baseline Pollutant Emission Levels
to Maximum Allowable Emissions
Summary of Potential Pollutant/Combustion Source
Hazards
Page
90
92
93
96
vn
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SECTION 1
INTRODUCTION
This report summarizes the results of the first year of the
"Environmental Assessment of Stationary Source NOX Combustion Modification
Technologies" (NOX E/A). The NOX E/A is a 3-year program to: (1) identify
the multimedia environmental impact of stationary combustion sources and NOX
combustion modification controls; and (2) identify the most cost-effective,
environmentally-sound NOX combustion modification controls for attaining and
maintaining current and projected NOg air quality standards to the year 2000.
During the first year, program effort concentrated on three areas: (1)
developing the methodology for environmental assessment and process
engineering studies; (2) compiling data on source process characteristics,
emissions, and pollutant impacts; and (3) setting program priorities on
sources, controls, pollutants, and impacts. This report reviews each of
these areas and summarizes our plans for future effort, with emphasis on the
second year.
1.1 BACKGROUND
The 1970 Clean Air Act Amendments designated oxides of nitrogen (NOX)
as one of the criteria pollutants requiring regulatory controls to prevent
potential widespread adverse health and welfare effects. Accordingly, in
1971, EPA set a orimary and secondary National Ambient Air Quality Standard
(NAAQS) for N0£ of 100 yg/m3 (annual average). To attain and maintain the
standard, the Clean Air Act mandated control of new mobile and stationary NOX
sources, each of which emits approximately half of the manmade NOX
nationwide. Emissions from light-duty vehicles (the most significant mobile
source) were to be reduced by 90 percent to a level of 0.25 g N02/km (0.4
g/mile) by 1976. Stationary sources were to be regulated by EPA standards of
performance for new stationary sources (NSPS), which are set as control
techno logy-becomes available. Additional standards required to attain air
quality in the Air Quality Control Regions could be set for new or existing
sources through the State Implementation Plans (SIPs).
Since the Clean Air Act, techniques have been developed and
implemented that reduce NOX emissions by a moderate amount (30 to 50 percent)
for a variety of source/fuel combinations. In 1971 EPA set NSPS for large
steam generators burning gas, oil, and coal (except lignite). Currently,
a more stringent standard for bituminous coal-fired large steam generators
is being considered, based on technology developed since 1971. Standards
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are also being prepared for lignite-fired large steam generators, gas
turbines, reciprocating internal combustion engines and intermediate-sized
steam generators. Local standards also have seen set, primarily for new and
existing large steam generators and gas turbines, as parts of State
Implementation Plans in several areas with NOX problems. This regulatory
activity has resulted in reducing NOX emissions from over 200 stationary
sources by 30 to 50 percent. The number of controlled sources is increasing
as new units are installed with factory-equipped NOX controls.
Emissions have been reduced comparably for light-duty vehicles. Al-
though the goal of 90-percent reduction (0.25 g N02/km) by 1976 has not been
achieved, emissions were reduced by about 25 percent (1.9 g/km) for the 1974
to 1976 model years and now have been reduced by 50 percent to 1.25 g/km.
Achieving the 0.25 g/km goal has been deferred indefinitely because of
technical difficulties and fuel penalties. Initally the 1974 Energy Supply
and Environmental Coordination Act deferred compliance to 1978. Recently,
the Clean Air Act Amendments of 1977 abolished the 0.25 g/km goal and
replaced it with an emission level of 0.62 g/km (1 g/mile) for the 1981 model
year and beyond. However, the EPA Administrator has requested the option
of reviewing the 0.25 g/km standard in 1983 if studies of the effect of N02
on human health show a review to be necessary.
Because the mobile source emission regulations have been relaxed,
stationary source NOX control has become more important for maintaining air
quality. Several air quality planning studies have evaluated the need for
stationary source NOX control in the 1980's and 1990's in view of recent
developments (References 1 to 7). These studies all conclude that relaxing
mobile standards, coupled with the continuing growth rate of stationary
sources, will require more stringent stationary source controls than current
and impending NSPS provide. This conclusion has been reinforced by projected
increases in the use of coal in stationary sources. The studies also
conclude that the most cost-effective way to achieve these reductions is by
using combustion modification NOX controls in new sources.
It is also possible that separate NOX control requirements will be
needed to attain and/or maintain additional N02-related standards. Recent
data on the health effects of N0£ suggest that the current NAAQS should be
supplemented by limiting short-term exposure (References 4 and 8 to 10).
In fact, the Clean Air Act Amendments of 1977 require EPA to set a short-
term NO;? standard for a period not to exceed 3 hours. Currently, EPA plans
to consider a short-term standard in 1978 when the N02 air quality criteria
document (Reference 11) is updated (References 12 and 13).
EPA is continuing to evaluate the long-range need for additional NOX
regulation as part of strategies to control oxidants or pollutants for which
NOX is a precursor, e.g., nitrates and nitrosamines (References 4, 8, and 12
through 15). These regulations could be source emission controls or
additional ambient air quality standards. In either case, additional
stationary source control technology could be required to assure compliance.
In summary, since the Clean Air Act, near-term trends in NOX control
are toward reducing stationary source emissions by a moderate amount. Hardware
modifications in existing units or new units of conventional design will be
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stressed. For the far term, air quality projections show that more stringent
controls than originally anticipated will be needed. To meet these
standards, the preferred approach is to control new sources by using low-NOx
redesigns.
1.2 PROGRAM OVERVIEW
Existing combustion modification techniques are increasingly being
used, and the prospects for developing and using advanced techniques are
good. Thus, there is a critical need to evaluate the environmental,
economic, energy, and engineering implications of combustion modification
technology. The NOX E/A was begun in June 1976 to provide these evaluations
and to specifically assess:
a The impacts, and potential corrective measures, associated with
using specific existing and advanced combustion modification
techniques, such as:
The change in gaseous, liquid, and solid emissions to the air,
water, and land caused by NOX controls
-- The capital and operating cost of NOX controls per unit
reduction in NOX
The change in energy consumption efficiency
The change in equipment operating performance
t The priorities and schedule for NOX control technology development
considering:
The above impacts for each source/control combination
~ The need for controls to attain and maintain the current
annual average N02 ambient air quality standard
-- The need for controls to attain and maintain a potential short-
term NO? standard, or other N0x-related standards such as a
standard for oxidants
Alternate mobile source standards
Alternate energy and equipment use scenarios, to the year
2000, in the Air Quality Control Regions with a potential NOX
problem
The first problem evaluates the net impacts from specific combinations
of stationary combustion source equipment and control techniques. The NOX
E/A addresses this question through a series of coordinated efforts to
evaluate the environmental impact and control potential of multimedia
effluents from current and emerging energy and industrial processes.
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The assessment effort is focused in a major process engineering and
environmental assessment task. This task is supported by additional tasks on
emission characterization, pollutant impacts and standards, and experimental
testing. Results from these tasks will be used to rank both current and
emerging source/control combinations based on overall environmental,
economic and operational impact. This information is intended to help
control developers and users select appropriate control techniques to
meet regulatory standards now and in the future. It also will define pollution
control development needs and priorities, identify economic and environmental
trade-offs among competitive processes, and ultimately guide regulatory
policy. In this respect, the NOX E/A will contribute to the broad program of
assessments of energy systems and industrial processes being administered by
EPA's Office of Research and Development.
The second problem above deals with specifying the best mix of control
techniques to meet air quality goals up to the year 2000. In the NOX E/A,
this is addressed in a systems analysis task which projects air quality in
specific air quality control regions for scenarios of NOX control, and energy
and equipment use. These projections, together with the control cost and
impact data discussed above will suggest the most cost-effective and
environmentally-sound controls. Results from the analysis are used in the
NOX E/A program to set priorities on both sources and controls. More
importantly, this information will help guide R&D groups concerned with
providing a sufficient range of environmentally-sound techniques to meet the
diverse control implementation requirements. It will also aid environmental
planners involved in formulating abatement strategies to meet current or
projected air quality standards.
The interrelationships and technical content of the tasks cited above
are shown in Figure 1-1. In this figure, the arrows show the sequence of
subtasks and major interactions among tasks, while the circled numbers refer
to sections of the report where the results are summarized. Section 4, not
shown in Figure 1-1, summarizes environmental objectives development
activities which support the total program.
The first year, NOX E/A effort developed the supporting data and
methodologies for conducting subsequent major program tasks: process
engineering and environmetal assessment, and systems analysis. The initial
effort concentrated on three general areas: compiling data on combustion
sources, pollutant impacts, control techniques, and emissions; developing the
environmental assessment and process engineering methodology; and setting
program priorities for sources, controls, pollutants, and impacts. In this
report, the first year results are presented in terms of these three areas,
rather than by tasks. This approach is in keeping with the annual report
format for the environmental assessments developed within IERL-RTP Energy
Assessment Control Division.
Initial program efforts were recently documented in depth in a preliminary
environmental assessment report (Reference 16). This report provides more
detailed discussion of many program results reported herein.
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EMISSION
CHARACTERIZATION
IMPACTS &
STANDARDS
EXPERIMENTAL
TESTING
PROCESS ENGINEERING &
ENVIRONMENTAL ASSESSMENT
©
COMPILE COMBUSTION
SOURCE PROCESS
BACKGROUND
GENERATE MULTIMEDIA
EMISSION INVENTORY
0
CHARACTERIZE PRIHARV
& SECONDARY MULTI-
MEDIA POLLUTANTS
*
DEFINE MULTIMEDIA
©
EVALUATE DATA ON
INCREMENTAL EMISSIONS
WITH NOX CONTROLS
i
cn
SYSTEMS
ANALYSIS
COMPILE HOX
CONTROL PROCESS
BACKGROUND
©
DEVELOP PRELIMINARY
MODEL FOR ENVIRONMENTAL
ALTERNATIVES STUDY
ENVIRONMENTAL GOALS
CONTROL PRIORITIES Oil
OF POTENTIAL IN
1 PROJECTED USE
GENERATE EMISSION
PROJECTIONS & REGIONAL
VARIATIONS
CONDUCT FIELD
TESTS
ENVIRONMENTAL
GOALS
COMPARE CONTROLLED
EMISSIONS TO
MULTIMEDIA GOALS
COMPARE BASELINE
EMISSIONS TO MULTIMEDIA
ENVIRONMENTAL GOALS
SELINE AND
CONTROLLED EMISSION
DATA
IMPACT CRITERIA
STANDARD PROJECTIONS
RANKING OF POTEN-
TIAL IMPACTS MITH
USTION MODIFICATI
CONTROLS
BASELINE IMPACT
ASSESSMENT
0
SCREEN CONTROL
REQUIREMENTS FOR
AIR OUALITY MAIN-
TENANCE
SELECT AMD ADAPT
REACTIVE AIR QUALITY
rwoEL
*
PROJECT SOURCE
GROWTH * AI1BIENT
STAtlOARDS
»
ASSESS CONTRllL
REOUlREMEtlTS FOR
ALTERNATE ABATEMENT
STRATEGIES
> COMPLETED
EFFORT
nnr.ni':r.
Fnnn"
EFFOPT
CKIBU'.Timi HODI-
fFICATlON CONTROL IKYtl-J
OPMEtlT PRIORITIES
Figure 1-1.
NO E/A approach.
A
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SECTION 2
CURRENT PROCESS TECHNOLOGY
This section presents the preliminary characterization of NOX sources
used to order and simplify the NOX E/A environmental assessment and process
engineering studies. This characterization categorized equipment design
according to characteristics that affect the formation and/or control of
multimedia pollutants. Emphasis was on stationary combustion sources of NOX.
However, the other sources of NOX also were studied, since the degree of NOX
control possible on these sources determines the extent of NOX control needed
for stationary combustion sources. The categories of equipment described in
this section were used as the base for the emission inventory discussed in
Section 7.1 and to rank the sources as discussed in Section 8. The source
characterization performed encompassed the following steps:
Identify significant sources of NOX; group sources according to
formative mechanism and nature of release into the atmosphere
Categorize stationary combustion sources according to equipment
and fuel characteristics that affect the generation and/or control
of combustion-generated pollution
Qualify equipment/fuel categories on the basis of current and
projected use and design trends; develop a list of equipment/fuel
combinations to be carried through subsequent emission inventories,
process studies, and environmental assessments
Identify effluent streams from stationary combustion source
equipment/fuel categories which may be affected by using NOX
combustion modification controls
Identify operating modes (transients, upsets, maintenance) in
which emissions may be affected by NOX combustion modification
controls
The significant sources of oxides of nitrogen emitted to the
atmosphere are shown on Figure 2-1. On a global basis, natural emissions
from biological decay and lightning make up about 90 percent of all NOX
emissions. In urban areas, however, up to 90 percent of the ambient NOX may
be due to manmade sources, primarily combustion effluent streams. The
emphasis in the NOX E/A will be on the fuel combustion sources bracketed at
the top of the figure. The remaining sources will be considered only
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00
Sources of
nitrogen
oxides
Combustion
'effluent stream
emissions
Noncombustton
effluSnt
stream
emissions
fugitive .
emissions
-Statlonary-
rFuel
combustion
-Incineration
Mobile
rNatural-
Anthropogenlc
Utility boilers
Packaged boilers
Harm air furnaces
Gas turbines
Reciprocating 1C engines
Industrial process combustion
Advanced combustion processes _,
. Emphasis
> of
HOX E/A
-Nitric acid
-Adlplc acid
Explosives
-Fertilizer
-Nitration
Nitrogen cycle
Lightning
-Open burning
KForest fires
Structural fires
-Minor processes
Figure 2-1. Sources of nitrogen oxide emissions.
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as required to gauge the emissions and impacts due to stationary fuel
combustion.
The major stationary fuel combustion source classes have been further
categorized as shown in Table 2-1. This table lists the major equipment
designs, types, and corresponding fuels fired, and was compiled from a survey
of installed sources, process characteristics and emission data. Major
source categories are discussed in the following sections.
2.1 UTILITY BOILERS
Utility boilers are field-erected watertube boilers with capacities
greater than 25-MW electrical output. These boilers generally burn
pulverized coal, residual oil, and natural gas. Recent designs have
multifuel capabilities, using coal as the primary fuel. Although there is
a large variety of specific boiler designs, the primary design characteristic
affecting NOX emissions is the firing pattern. The three generic firing
types are tangential, horizontally-opposed, and single wall. Generally,
tangential boilers and a variation of horizontally-opposed boilers known as
Turbofurnace have furnace mix burner designs, in which fuel and secondary air
are mixed in the furnace. Single wall and horizontally-opposed boilers
generally have register mix burner designs, where secondary air and fuel are
premixed in the burner register.
Three other firing designs exist in older equipment, but these designs
are not presently being used in boilers sold for utility applications. The
cyclone furnace was designed to fire pulverized coal, especially slagging
coals, but also is used for oil and gas. Inflexibility in its normally high
operating temperatures has made this design obsolete for all but high sodium
lignite firing. Another design, the vertical furnace boiler, was popular
before the advent of waterwalled combustion chambers. The third design, stoker
firing, is seldom used in utility boilers because of capacity limitations
and high costs.
A design survey of the installed population indicated that wall-fired
boilers make up almost 60 percent on a number basis; tangential, 20 percent;
vertical and stoker, 10 percent; horizontally-opposed, 8 percent; and
cyclones, 3 percent. However, this distribution does not reflect respective
importance from a NOX standpoint. For example, wall-fired units are
generally smaller boilers, while horizontally-opposed boilers are primarily
large capacity designs. In addition, vertical, stoker, and cyclone boilers
are obsolescent.
Utility boilers produce gaseous, liquid, and solid effluents. The
flue gas stream contains combustion-generated air pollutants, ash particles,
and volatile fuel contaminants. Liquid streams include the ash sluicing
water, for coal-fired dry bottom boilers, the molten ash stream for wet
bottom boilers, and the scrubber waste stream if a scrubber is used. Solids
include hopper ash from particulate control devices, and bottom ash from
boilers that do not use sluicing water.
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TABLE 2-1. SIGNIFICANT STATIONARY FUEL COMBUSTION EQUIPMENT
TYPES/MAJOR FUELS
Utility Sector (Field Erected Water-tubes) Fuel
Tangential PC, 0, G
Wall-fired PC, 0, 6
Horizontal-opposed and Turbofurnace PC, 0, 6
Cyclone PC, 0
Vertical and stoker C
Packaged Boiler Sector
Watertube 29 to 73 MWa PC, 0, 6, PG
(100 M to 250 MBtu/hr)
Watertube <29 MWa C, 0, G, PG
(<100 MBtu/hr)
Firetube scotch 0, G, PG
Firetube HRT C, 0, G, PG
Firetube firebox C, 0, G, PG
Cast iron 0, G
Residential C, 0, G
Warm Air Furnace Sector
Central heaters 0, G
Space heaters 0, G
Other residential combustion 0, G
Gas Turbines
Large >15 MWa (>20,000 hp) 0, G
Medium 4 to 15 MWa
(5,000 to 20,000 hp) 0, G
Small <4 MWa (<5,000 hp) 0, G
10
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TABLE 2-1. Concluded
Reciprocating 1C Engines
Large bore >75 kW/cyla 0 G
(>100 hp/cyl)
Medium >75 kW to 75 kW/cyla 0 6
(100 hp to 100 hp/cyl)
Small <75 kWa (<100 hp) 0, 6
Industrial Process Heating
Glass melters
Glass annealing lehrs
Cement kilns
Petroleum
Catalytic crackers
Process heaters
Brick and ceramic kilns
Iron and steel coke oven
Underfire
Iron and steel sintering machines
Iron and soaking pits and reheat ovens
PC Pulverized coal
C Stoker coal or other coal
0 Oil
G Gas
PG Process gas
aHeat input
11
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Typical operating conditions for utility boilers are: volumetric heat
release of 104 to 250 kW/m3 for coal-firing and 208 to 518 kW/m3 for oil or
gas boilers; furnace pressures from -50 to 1000 Pa; and excess air levels of
25 percent for coal, 10 percent for oil, and 8 percent for gas.
Trends in utility boiler design show pulverized coal becoming the
dominant boiler fuel, with balanced draft combustion chambers increasingly
being used. Also, in recent years orders for two boilers of moderate
capacity have become more common than single orders for a very large boiler.
2.2 PACKAGED BOILERS
The packaged boiler category includes all industrial, commercial, and
residential packaged boilers. Generally, these boilers have capacities less
than 73-MW thermal input (250 MBtu/hr). There are only a few package boilers
with larger capacity and these are sufficiently similar to the smaller units
to be included in this category.
Packaged boilers are constructed in watertube, firetube, cast iron,
and shell designs; each design has a fairly distinct capacity range. These
boilers are fueled primarily by residual and distillate oil, natural gas, and
stoker coal. In addition, liquid and solid waste fuels and process gases are
sometimes burned.
Package watertube boilers span the larger capacity range of this
equipment sector. A single burner generally is used, but multiple-burner
units also exist. Burners are always mounted on a single wall. Although
stoker-fired package watertube boilers currently make up less than 15 percent
of the installed population, there is increasing interest in using them
because of the desire to shift to coal-firing. Pulverized coal units are
available currently, but generally are too expensive.
In firetube boilers, combustion products are directed from the
combustion chamber through straight tubes submerged in water. Because they
are sensitive to fouling, firetube boilers normally burn fuel oils and
natural gas, rather than coal or other high ash fuels. Large firetube
boilers burn mainly residual oil and natural gas, while smaller boilers burn
natural gas and distillate oil.
The other types of package boilers (cast iron and shell boilers) are
minor equipment types in terms of installed capacity. They are used
primarily to supply low-pressure steam or hot water for air and water heating
systems.
Flue gases usually are the only combustion-related effluent from
packaged boilers. If pulverized or stoker coal, solid wastes, or other high
ash fuels are burned, both liquid and solid effluents are produced when ash
collection and flue gas cleanup systems are used.
Operating conditions for package boilers vary greatly according to
equipment design, capacity, and application, and therefore only very general
operating conditions can be given. Usually, these boilers operate at
12
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atmospheric combustion chamber pressure and at excess air levels somewhat
higher than utility boilers. Combustion efficiency also is usually less than
that of utility boilers.
Recent trends show a strong movement toward large capacity package
watertube boilers with multifuel capabilities. In addition, pulverized coal
boilers are becoming more commonly used in the large capacity range.
2.3 WARM AIR FURNACES AND OTHER COMMERCIAL AND RESIDENTIAL COMBUSTION
EQUIPMENT
This source category is made up of residential and commercial warm air
furnaces used for comfort heating, and miscellaneous commercial and
residential appliances used in cooking, refrigeration, air-conditioning,
clothes drying, and the like. Emphasis in the NOX E/A has been on
characterizing warm air furnaces, which come in two basic types: space
heaters, where the unit is located in the room or area it heats; and central
heaters, which use ducts to transport and discharge warm air into the heated
space.
"According to U.S. Census statistics for 1970, over 55 percent of the
nation's heating units were warm air furnaces. About 67 percent of these
units burned natural gas, while 23 percent burned distillate fuel oil. Coal,
wood, and various bottled, tank, or LP gas accounted for the remaining 10
percent of fuel used. Despite a continuing trend recently toward burning
natural gas in commercial and residential warm air furnaces, the fraction of
equipment using this fuel is expected to drop from 37 percent in 1974 to 35
percent by 1985, and to 32 percent by 2000 (Reference 17).
Flue gases are generally the only combustion-related effluent from
warm air furnaces. For rarely used, solid-fueled furnaces, solid waste
consisting of dry ash would be produced.
One of the most important characteristics of all comfort heating
devices is their cyclic operation. Typical residential warm air heaters go
through two to four cycles per hour, with an overall on-time generally less
than 50 percent. Cyclic operation is important for two reasons: first, emissions
during startup and shutdown may be substantially higher than during continuous
operation; and second, the thermal efficiency of these furnaces is substantially
lowered by heat losses to the flue between cycles.
2.4 GAS TURBINES
Gas turbines are rotary internal combustion engines fueled mainly by
natural gas, diesel or distillate fuel oils, and occasionally by residual or
crude oils. These units range in capacity from 30 kW (40 hp) to 100 MW
(134,000 hp) heat input and may be installed in groups for larger power
output.
Gas turbines have been extremely popular in the past decade. They
have relatively short construction lead times, low initial cost, light
13
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weight, low vibration level, ease and speed of installation, and low physical
profile (low buildings, short stacks, little visible emissions, quiet
operation). In addition, factors like remote operation, low maintenance,
high power-to-weight ratio, and short startup time have added to their
popularity.
Large-capacity gas turbines can range up to 100 MW (134,000 hp), while
combined-cycle and multiple turbines can range up to 1230 MW. These
equipment types are used almost exclusively by electric utilities. Medium
capacity units have capacities up to 15 MW (2000 hp) and are generally used
for standby electrical generation, pipeline pumping, and industrial power
generation. Gas turbines less than 4 MW (5000 hp) capacity are used for
pipeline pumping and standby electrical generation, but these units represent
less than 5 percent of the total installed gas turbine capacity.
Stationary gas turbines are normally operated at constant speed and
output. Combustion normally occurs at equivalency ratios of about 1.5 and at
high pressure (up to 10 atmospheres).
Large gas turbine designs have recently tended towards higher
capacities and improved heat rates. Because of their improved heat rate and
fuel flexibility, combined-cycle turbines seem to be the preferred design for
intermediate or base load applications in the future. Simple-cycle turbines
will be preferred for peaking. Also, because of the trend in utilities
(which purchase over 90 percent of the turbine capacity currently sold)
toward larger turbines, and the movement in the oil and gas industry toward
smaller turbines, fewer medium-capacity gas turbines will be sold.
2.5 STATIONARY RECIPROCATING 1C ENGINES
Reciprocating 1C engines for stationary applications range in capacity
from 750 W (1 hp) to 48 MW (50,000 hp) heat input. These engines are either
compression ignition (CI) units fueled by diesel oil or a dual-fuel
combination of natural gas and diesel oil, or spark ignition (SI) engines
fueled by natural gas or gasoline. These engines are popular because of
their versatility, load following characteristics, high efficiency, and
capability for remote operation. They are used for applications ranging from
shaft power for large electrical generators and pipeline compressors to small
air compressors and welders.
Large bore 1C engines are typically high power, low or medium speed,
4-stroke CI units fueled by diesel oil or dual fuel. However, many natural
gas-fueled 2- and 4-stroke SI units also exist in this capacity range. Dual-
fueled engines and natural gas-fueled spark ignition engines account for 93
percent of all the fuel consumed by these large capacity engines. Most of
these engines are used to drive compressors in the oil and gas industry.
The primary manufacturers of medium capacity units also make similar
engines for trucks, tractors, and construction equipment. As a result,
medium power stationary engines tend to be modified mobile engines, with
rotative speeds greater than 1000 rpm. Engines in this capacity range
usually burn either diesel or gasoline rather than natural gas. They are
14
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used mainly in construction, agriculture, and industry for shaft power,
pumping, and compressing.
Small 1C engines are mainly one- or two-cylinder units fueled by
gasoline or occasionally diesel oil. They are used mainly for generator
sets, refrigeration compressors for trucks and railcars, small pumps, and
off-the-road vehicles.
Due to the extremely large number of designs, fuels, and applications,
general operating characteristics of this source category are impossible to
describe. Many factors, including air-to-fuel ratio, timing, fuel
properties, compression radio, and chamber design, can influence combustion
characteristics.
2.6 INDUSTRIAL PROCESS HEATING
Significant quantities of fuel are consumed by industrial process
heating equipment in industries such as iron and steel production, glass
manufacture, petroleum refining, sulfuric acid manufacture, and brick and
ceramics manufacture. In addition, there are dozens of industrial processes
such as coffee roasting, drum cleaning, paint curing ovens, and smelting of
metal ores that burn smaller amounts of fuel. Fuels fired in these units
include oil, natural gas, producer gas, refinery gas, and occasionally coal.
Because of the wide variety of equipment design types and fuels
(especially "waste" fuels) used in this source category, few generalizations
can be made. Therefore, only little effort in this program was devoted to
characterizing this source class. Future efforts will characterize this
category in more detail.
2.7 SUMMARY
The primary and secondary design types from the equipment categories
above are summarized in Table 2-2. The primary design types were selected on
the basis of design trends, and are projected to be in widespread use in the
1980's. Thus, they are candidates for applying NOX controls. The secondary
design types listed are those which are either diminishing in use or
projected primarily for long term applications. In either case they will
probably not require widespread use of NOX controls in the near future.
The lists of effluent streams and significant operating modes on Table
2-2 were generally used throughout the emission inventories, and will be used
later in ranking pollution potential from specific effluent streams.
However, data on the frequency and specific process conditions of nonstandard
operating modes were sparse.
Source characterization activities are continuing to define more
precisely the high priority stationary sources of NOX. These continuing
efforts will:
15
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TABLE 2-2. SUMMARY OF SOURCE CHARACTERIZATION
Sector
Utility
boilers
Packaged
boilers
Warm air
furnaces
Gas turbines
Reciprocating
1C engines
Industrial
process
combustion
Primary Design
Types 1n NOX E/A
Tangential* wall-
fired, horizontally
opposed turbofurnace
Watertube, scotch
flretube
Commercial and
residential central
warm air furnaces
Utility and Indus-
trial simple and re-
generative cycle
Turbocharged,
naturally aspirated
Secondary Design
Types 1n NOX E/A
Cyclone, verti-
cal, stoker
HRT flretube,
firebox fire-
tube, cast Iron
and residential
Space heaters,
other residen-
tial combustion
Combined cycle,
repowerlng
Blower
scavenged
Process heaters,
furnaces, kilns
Effluent Streams
Stack gas, partlculate
catch, bottom ash,
scrubber streams, ash
sluicing streams
Stack gas, partlcu-
late catch, hopper
ash
Flue gas
Flue gas
Flue gas
Flue gas, partlcu-
late catch, hopper
ash
Significant
Operating
Modes
Sootbl owing,
on-off transients,
load transients,
upsets, combustion
additives
As above
On-off cycling
transient
On-off transient,
load following,
Idling at spin-
ning reserve
On-off transients,
Idling
Charging opera-
tions, upsets,
starting transi-
ents
Trends
Coal-firing 1n new units;
conversion to oil and
coal 1n existing units:
few new wet bottom, cy-
clones, stoker or verti-
cal units
Pulverized coal and
stokers 1n large water-
tubes; heavy oil and
stokers In smaller water-
tubes; heavy oil 1n fire-
tubes; decreasing use of
HRT and firebox flretubes
011 firing and trend
to high efficiency 1n
new units
Trend to higher turbine
Inlet temperature, larger
capacity and oil firing
1n new units; rapid
growth projected
Low growth rate of dlesel
units
Increasing use of coal In
kilns; some use of syn-
thetic gases from coal
cr>
-------
Determine geographic distributions of equipment by fuel and firing
type
Refine trends in equipment design, sales, fuels, and conversion
to alternate fuels
Further characterize both liquid and solid effluents originating
from stationary combustion sources
Characterize nonstandard operating conditions in terms of frequency,
duration, and effect on NOX formation mechanisms
Further characterize the industrial process heating sector
17
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SECTION 3
CURRENT ENVIRONMENTAL BACKGROUND
The NOX E/A involves separate assessments of the impacts of:
1. Multimedia pollutants from a single uncontrolled (for NOX) source
on human health and terrestrial and aquatic ecology
2. Multimedia pollutants from a single controlled source on human
health and terrestrial and aquatic ecology
3. NOX control strategies applied to sources in Air Quality Control
Regions on ambient concentrations of N02 and oxidants
The assessment methodology for each of these consists of the following three
elements:
An emission inventory listing all multimedia effluents crossing
the plant boundary (cases 1 and 2 above), or listing all NOX
emissions within an AQCR (case 3), including quantities emitted
and temporal variations in emissions
t A transport analysis model which accounts for dispersion effects
and chemical or physical transformations to estimate ambient
concentrations
0 A set of impact criteria which describes the set of acceptable
ambient pollutant concentrations
NOX E/A efforts to date have emphasized selecting suitable impact
criteria. -These criteria will be used in two ways. In some cases, a goal
for emission levels or control system effectiveness will be specified, and
the overall impact of this goal on the environment will be determined from
the methodology. In other cases, a goal for pollutant ambient concentration
will be specified and the requirements for emission levels or control systems
will be determined from the methodology. These emission-based goals,
together with health/ecology-based goals, are termed "Multimedia
Environmental Goals" (MEGS)-
The first year of the NOX E/A has been spent establishing requirements
for multimedia environmental goals, surveying pollutant effects research
19
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methods suitable for use in setting MEGS, and deriving preliminary
health/ecology-based MEGS. The results of these efforts are summarized
below.
3.1 MULTIMEDIA ENVIRONMENTAL GOALS DATA REQUIREMENTS
Ideally impact assessments in the NOX E/A will need to consider
potential pollutant impacts on:
Human health through inhalation
Human health through ingestion
Aquatic plants and animals
Terrestrial plant and animals
In these assessments, the impacts of oxides of nitrogen and secondary
pollutants from NOX (oxidants, nitrates) will be given special consideration,
since they directly relate to the need for NOX control systems. Material
impacts and the impacts of noise and thermal pollution will be given
secondary emphasis.
The MEGS data required in assessing the above impacts change as the
program progresses. Initially, approximate impact screening concentrations
are needed for the "universe" of potential pollutants emitted by sources
under consideration. These screening concentrations, when compared to
emission measurements or estimates, allow relative priorities to be set on
sources, effluents, and pollutants. Subsequently, more detailed data on
impacts and effects are needed to quantify impacts of the smaller class of
sources, effluents, and pollutants given high priority in the program. At
this stage, more precise analyses of potential secondary pollutants can also
be made.
To date, the major effort in establishing MEGS has focused on
developing the impact screening concentrations. Gaseous stream pollutants
were emphasized since these include the vast majority of combustion-generated
pollutants potentially affected by combustion modification NOX controls.
Initial surveys of dose-response data and discussions with pollutant impact
researchers indicated that impact screening concentrations based largely on
impacts on human health through inhalation would be most appropriate. These
impacts are the most readily identified and quantified for gas stream pollutants.
Impact on human health through ingestion depends heavily on site-specific
food chain vectors, and cannot be easily generalized for screening purposes.
Terrestrial and aquatic effects are also highly dependent on site-specific
or regional conditions. These may be treated in the impact screening .on a
"worst case" basis, but such considerations offer little insight beyond that
gained from using human health impacts through inhalation.
20
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3.2 RESEARCH METHODS
A variety of research techniques has been used to evaluate pollutant
toxicity. The following subsections discuss these techniques and their relevance
to the current program. Research methods which evaluate human health effects
are considered in the first subsection; aquatic and terrestrial effects are
considered in the second.
3.2.1 Methods to Assess Ambient Pollutant Health Effects
Many research methods have been used to study the toxic effects of
inhaled substances. These include long- and short-term laboratory animal
studies, short-term human experiments, case reports and industrial hygiene
reports, and epidemiologic studies on exposed workers and general
communities. However, each of these methods is limited, and cannot
unambiguously be used to estimate ambient exposure limits which protect the
general population. For example, animal study is the only practical method
for assessing long-term response to controlled exposure, but extrapolation to
human effects is qualitative at best. Similarily, it is difficult to
predict the effects of continuous long-term exposure from the results of
short-term human experiments.
In view of the above, it is not surprising that the available data
base on the health effects of pollutant exposure is quite limited. Clearly,
it is not possible to identify with certainty an ambient concentration at
which a particular health effect may be expected to occur. Conversely, it is
also impossible to identify levels at which no adverse affect is expected.
Indeed, for many substances considered, the published literature contains no
accounts of human or animal exposures at levels that even approximate
typical ambient concentrations.
Acknowledging the lack of suitable data, Research Triangle Institute
(RTI) has developed a method for estimating permissible ambient concentrations
for community exposure using occupational threshold limit values (TLVs) and
animal LD50s (Reference 18). However, there are obvious limitations to
basing permissible pollutant levels on TLVs and LDSOs. For example, TLVs
were established to protect a largely healthy, male adult population from
intermittent exposure, whereas a permissible level should protect an entire
community from continuous exposure. Likewise using animal LDBOs to estimate
allowable ambient levels is subject to all the difficulties inherent in
extrapolating animal results to human effects.
RTI has taken these difficulties into account and has developed
formulas to estimate what continuous pollutant exposure is hazardous to the
health of the general public. The two equations used in the present study
are x - 1.65 x 10"3 (TLV) and x = 4.77 x 10~5 (LD50) where x is defined as
"the pollutant concentration (ug/m3) for which continous exposure with 100-
percent absorption causes a stationary maximum body concentration equal to
0.05 percent LD50 value of the compound, assuming a biological half-life of
30 days," and LD50 is the oral LD50 for rats.
21
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RTI emphasizes that these estimated concentrations, x, are not
applicable to known or suspected mutagens, carcinogens, or teratogens, and
can be applied only to substances whose biological half-life is short
compared to the average human life. In addition, these formulas, based upon
a "one-compartment model with a single, first-order excretion rate," do not
account for synergistic interactions between pollutants, and assume that all
pollutants entering the respiratory system are retained by the body.
This approach is unavoidably simple since it makes many assumptions
and uses a single expression to predict safety levels for a wide variety of
pollutants. However, assumptions concerning rates of excretion, age
differences in respiratory uptake, and corrections for the intermittent
nature of occupational exposures are reasonable. On the other hand, assuming
100 percent absorption, even distribution of inhaled pollutants throughout
the body, and the applicability of animal LD50 data to man may limit the
usefulness of these calculations. Still, since no other data were available,
the RTI formulas were used to generate the permissible ambient concentration
levels used in the present effort.
3.2.2 Methods of Assessing Pollutant Impacts on Biota
The following three levels of evaluation are generally used to
describe pollutant impact on terrestrial and aquatic biota:
0 "First Estimate" Techniques, which include methods for making
rapid (and preliminary) assessments of adverse effects specific
chemicals may have on aquatic or terrestrial biota
Experimental Establishment of Impact Concentrations, which
includes appropriate methods for establishing experimental
concentrations of specific chemicals which will cause lethal or
sublethal damage in sensitive aquatic and terrestrial species
Site-Specific Techniques, which are methods to determine whether
pollutants at a particular site affect local aquatic and
terrestrial ecosystems
Unfortunately all existing techniques are limited. For example, most
approaches used to test a specific chemical have failed to evaluate interactive
phenomena such as synergistic, additive, or antagonistic behaviors of other
effluent stream chemicals. In addition, differences in the chemical tolerance
of species in different areas remain unexplored. Pollutant effects on different
life stages of a species are also often overlooked and sublethal effects are
largely undetermined. Furthermore, effects of alternative culturing times
and techniques, and the natural and acquired resistance natural populations
have to particular pollutants remain unexplored. Because of these and many
other limitations of available methods, conventional experimental techniques
often produce data with little value for assigning "safe" or permissible levels
of toxicity.
Moreover, certain site-specific techniques are rather crude and cannot
incorporate the controls necessary to establish causative relationships when
22
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damage is noted. Because of these and other problems, data generated from
all techniques have limited usefulness.
The current effort used only the very general first estimate
procedures to set the limits derived. Future program work will rely more
heavily on bioassay testing and site-specific techniques.
3.3 CONCENTRATION ESTIMATES FOR SCREENING COMBUSTION-RELATED POLLUTANTS
Using the methods described previously (and recognizing the
limitations-of these methods), and the available support information,
preliminary screening concentrations were estimated for all potential
combustion source pollutants identified. Screening concentrations were
derived for both human health effects and for effects on terrestrial and
aquatic biota and are reported in Reference 16. These data were then used
for preliminary screening and setting priorities. The data assembled will be
reviewed during subsequent impact assessment and test data collection tasks
of the NOX E/A. Results will be revised whenever new information requires.
The presentation of only the calculated levels herein does not reflect the
large volume of data on health effects which has been collected and reviewed.
The screening concentration values calculated were generated according
to the RTI method discussed above (except when an ambient air standard
existed and could be used instead). In most cases screening levels were
based on occupational threshold limit values using the 8-hour, time-weighted
average (TWA) TLV. In cases where a TLV was unavailable, concentrations were
estimated from LD50s. Oral LD50 values for rats were preferred, followed by
oral LD50 data for mice, and intraperitoneal and subcutaneous LDSOs. In a
few cases, TDLo (lowest published toxic dose) and LDLo (lowest published
lethal dose) were used. Although the RTI formulas have been discussed
previously, it should be repeated that these estimates are, at best, a rough
approximation.
Subsequent to the above effort, a draft final report describing
further RTI work was received (Reference 19). In general, this report
extended and elaborated on the previous RTI work and largely encompassed the
NOX E/A work done to date. The methodology was essentially the same as
reported previously, although the constants were changed slightly. For
example, the latest report recommends x = 2.38 x KT3 (TLV) in place of the
previous x = 1.65 x 10~3 (TLV). Because of the greater scope and detail of
these RTI activities, it was recommended that it be utilized instead for
further work in the NOX E/A program. This will also help in comparing the
impact assessment portions of NOX E/A to other environmental assessments
sponsored by EPA/IERL-RTP.
3.4 SUMMARY AND CONCLUSIONS
The purpose of the environmental background task is to survey
available pollutant impact data and from these, describe the approach and
Multimedia Environmental Goals required to conduct impact assessments.
A two-step approach has been selected. The first step uses approximate
23
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impact screening data for a large number of pollutant species. The second
step entails a more detailed impact assessment for a smaller number of
potentially hazardous pollutants.
A tentative list of screening MEGS has been compiled and used to set
priorities on sources, controls, effluent streams and impacts. This list has
recently been augmented with the RTI MEG data {Reference 20). Further NOX
E/A work in deriving impact screening MEGS will be limited. Most of the data
will be supplied by RTI, with review to ensure that the results are
appropriate for NOX E/A assessments. The use of impact screening MEGS for
ranking sources and pollutants will continue as new data become available.
Further environmental background effort centers on two tasks:
Assess site-specific impact factors, such as regional food chain
vectors, and regional terrestrial and aquatic ecology, to augment
environmental alternatives analyses made using MEGS
Survey the basis of existing standards and estimate further
standards for long- and short-term exposure to N02, oxidants,
nitrates, and other secondary pollutants for use in assessing the
impact of applying NOX control technologies
24
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SECTION 4
ENVIRONMENTAL OBJECTIVES DEVELOPMENT
In the NOX E/A, three assessments of pollutant impacts will be made:
Baseline Source Analysis: Compare ambient multimedia pollutant
concentrations from baseline (uncontrolled) stationary combustion
sources to multimedia environmental goals (MEGS)
Controlled Source Analysis: Compare ambient multimedia pollutant
concentrations from sources controlled for NOX to MEGS
a Environmental Alternatives Analysis (NOX): Compare ambient concentrations
of N02, resulting from using selected NOX control strategies on
a regional basis, to ambient air quality goals for N02
The first two assessments consider the impact from operating a single
source and include all potential multimedia pollutants. The third
assessment considers the impact from using NOX controls on a variety of
sources (typically within an Air Quality Control Region) but is restricted to
N0£ or NOg-related pollutants, such as oxidants.
All three assessments are performed in three steps:
Compile estimates of emissions and process data compatible with
the multimedia environmental goals
Estimate pollutant dispersion from a single source (for Baseline
or Controlled Source Analyses) or from a group of sources in an
AQCR (Environmental Alternatives Analysis) to relate ground level
concentrations to source emissions, considering methodology, source
configuration, and secondary transformations
Generate emission based or health/ecology based MEGS for use as
impact criteria
Various models are needed to relate these three steps in the methodology.
The complete methodology to be used is described in the following
subsections.
25
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4.1 IMPACT ASSESSMENT PROCEDURES
Key components of the three assessments, baseline source analysis,
controlled source analysis, and environmental alternatives analysis, are
shown sequentially in Figure 4-1. This sequence is used iteratively
throughout the NOX E/A. In the first year, a preliminary pass through the
sequence was made to set program priorities and identify data needs. This
first pass is being followed by subsequent passes in which more refined models
and more comprehensive emissions data and MEGS are used. Throughout the du-
ration of the program, all assessments will be repeated as new data are
obtained.
The baseline source analysis of each source serves two purposes.
First, it identifies the pollutants emitted by each source category which
should be evaluated further to see if a program to develop control technology
is warranted. Such an assessment could include collecting additional
emission data, conducting a careful dispersion analysis (or even a combined
emissions and ambient air test program), or developing a better estimate of
the health and welfare effects of the pollutant. Second, the baseline source
analysis identifies data needs for detailed process engineering evaluations
of NOX controls. The multimedia assessment also will indicate sources that
emit critical quantities of some pollutants, so that serious consideration
can be given to sampling that kind of source.
The baseline multimedia assessment will use a Source Analysis Model
(SAM) as described in Section 4.2. This model calculates a nationwide impact
factor for each source type (e.g., horizontally-opposed coal-fired utility
boilers) based on the relative importance of the ambient contribution of each
emitted pollutant to predetermined permissible concentrations, existing ambient
levels of those pollutants, the affected population, and the expected growth
of the source type.
The Source Analysis Model is also used in the Controlled Source Analy-
sis described in Section 4.3. In this analysis, however, more detailed
consideration is given to site-specific effects such as the formation of sec-
ondary pollutants through atmospheric reaction, and regionally-dependent
ecological conditions. The site-specific impact study will be conducted for
fewer source/effluent stream/pollutant combinations than in the baseline
source analysis. These combinations will be selected from priority ranking
of potential environmental hazards using the SAM.
The Environmental Alternative Analysis is the final step in the
assessment sequence. It uses the results of the source analysis models and
process studies to show the most environmentally-sound and cost-effective NOX
control system for attaining air quality goals for NOX. The environmental
alternatives analysis is also iterative; a preliminary pass through the steps
in this analysis has been conducted in the first year of the program. Both
the preliminary and the more refined determination of the need for controls
(based on attaining and maintaining N0x-related ambient air goals) are being
performed with the aid of systems analysis models, described in Section 4.4.
Modified rollback was used for the preliminary evaluations and will continue
to be the primary air quality model used in systems analyses. Weighting
factors will be incorporated into this model to account for stack height,
26
-------
Reed for
Environmental
Assessments of
Other rolluUnts
DetereriBe
Potentlil eultlaedli conctnii
(ttrtm mi effluents)
Dati needs (testing) for
proccti engineering
Sovree Ttttt
Emissions Oau
Baseline
Mselln
Source
). control
dut to
Process Engine
rcrlng
Cost B«U
Fuels AvilltbtHty
Eootpwnt Trendl
Tet.1 liptct *f cMtralllig W, frv
wire* t»
Coit
Energy
Incnaenul oi1»1oni of other
polluUnts/Bedl*
Unrciolved opentlonal protlem
Heeds for full-wile deKmstritl
Envl
kiseispent
| Soun
EnvlromenUl
(Total iBfuet) if
l»Di fro. Specif 1<
Source Category
Ccenarlof
Brovtk I fuels
e Mtenl ttanoarA
«sn
e Koblle sUnoarA
Preferred Controls
far Each tnel of
IB. Emissions Deductloiis
Controlled
Source
Analyst!
Regional Envli BMtntal
Analyili (System Inalysl
Air quality Hodel)
More Cost-Effective Ntans of
Achieving (D.-Kelated goals
In Representative AQC*s
for MO
nee*
Sce«t
» Schedule
Envtromtnul
Alternatives
Analysis
Figure 4-1. Impact assessment procedure.
27
-------
patterns. These weighting factors will be derived from a limited application
of photochemical dispersion models.
4.2 SOURCE ANALYSIS MODEL
The Source Analysis Model is primarily oriented towards a rapid
assessment of the potential of a given source for impacting the environment.
It considers the multimedia impact of each combustion source type under
baseline operating conditions and, by comparing these individual assessments,
ranks the sources in terms of overall pollution potential. The resulting
list will guide the selection of sources for which control devices need to be
developed or applied.
The following discussion describes the approach used for determining
the impact of a given source type on the air, water, and land.
4.2.1 Air Impact
The impact of a gaseous effluent stream on air quality will be deter-
mined by calculating the impact of each pollutant species in the discharge
and summing these individual impacts. The result is then multiplied by the
number of people exposed to the effluent, to produce the impact factor for
that source.
The first step is to identify a representative source with operating
characteristics and physical dimensions typical of all sources in its class,
(for example, wall-fired utility boilers/coal-fired). This model source
would have a specific fuel consumption rate, ESP efficiency, stack height,
etc. Using these data plus all necessary emission factors, the emission rate
of each pollutant species is calculated. Then, using a Gaussian dispersion
model (for point sources), or a HoIzworth model (for area sources) the ground
level concentration of each pollutant, X-jj, is calculated at or near the
source. An intermediate indication of the relative impact of each species is
given by the term
x (area affected)
where X-jj is the ground level concentration of pollutant j due to source i;
X/\j is a ground level concentration deemed sufficiently low to cause no
harmful effects (the Research Triangle Institute-derived MEG values will be
used); and the area affected is, for an area source, the ground area within
which all of the sources are located. For a point source, the term takes on
the form of an area integral of Xij/X^j over the regions in which X-jj is an
appreciable fraction of XA,-:
A,.. =
where A is the area surrounding the source.
28
-------
Other terms of interest can be calculated by replacing X-jj by (Xjj +
Xjg), where Xj3 is the ambient background of pollutant j near the source.
This background concentration varies from region to region, but only two
different values will be used: one representative of an urban area (Xjgu),
the other of a rural area (Xjgr).
The resulting terms are:
ij
= / (xij + xjBr)/xAj
L ' J J
dA (°r the corresponding
area source term)
and
where the integrals are taken over areas in which X-jj is an appreciable part
of the background or in which xij/x/y is large. These intermediate impact
terms calculated with the background terms result in a higher impact factor
for sources which are preferentially located in high background regions.
Thus, A-JJ is the impact due to source i of pollutant j by itself; B^j
is a measure of the importance of the pollutant in a typical rural setting;
and Cij is the corresponding measure for an urban location. A list of these
factors for a particular source indicates which pollutants are a potential
hazard .
The effect of all pollutants is then defined as the algebraic sum of
the terms for each species:
= E A.JJ
B-J = Z B-JJ
J
C,- = Z C
^,-
Unit impact of source by itself
Unit impact of source in rural area
Unit impact of source in urban area
The important effect of human exposure is incorporated by multiplying
these cumulative impact factors by the population density (persons/square
kilometer) in the exposed region and summing over the total number of urban
and rural sources of type i:
29
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where PR and Pu are the average rural and urban population densities and NR
and NU are the number of sources in rural and urban settings respectively.
In addition, an impact factor for a single source of type i can be defined by
dividing Ij by the sum of NR^ and NU-j. This new factor, 1-j1, still contains
information on the urban/rural split of source locations.
These factors, Ij and I.,-1, can be used initially to rank sources in
terms of their pollution potential. However, source growth rates and the
estimated future trends in applying available control methods have not yet
been considered, but are potentially significant. These factors will be
included by doing a complete source ranking for the years 1977, 1985, 1990,
and 2000, and comparing the resulting lists. In this way, the control R&D
priorities can be qualified to account for sources growing or diminishing in
importance.
4.2.2 Liquid and Solid Waste Impacts
Impact factors for liquid and solid effluent streams are much more
difficult to determine using the above approach than those for air. Sampling
data for liquid and solid waste streams are not nearly as complete as for gas-
eous streams, and the ultimate fate of the discharged pollutants is difficult
to determine. For example, mercury waste might be sent to a settling pond
where it could seep into the ground water and be absorbed by plants. The
mercury in the plants could then be ingested by humans eating either the plants or
meat from animals that have fed on the plants. The number of pathway scenarios
for liquid and solid effluents are far more numerous than for air emissions
and at present, we have no way of modeling the resulting dispersion by a method
suitable for application in this assessment.
Therefore, we have resorted to calculating impact factors using the
SAM/IA procedure (Reference 20). Here, the impact factor for a source is
defined as
:3 x Fe
where Xgj is the concentration of pollutant j in the effluent stream;
is a Minimum Acute Toxicity Effluent concentration determined by Research
Triangle Institute (RTI) (Reference 19), and Fe is the effluent stream flowrate,
The XMAJE values are suggested by RTI as effluent concentrations which, given
minimal dispersion, will not result in harmful environmental impacts.
The results of these calculations will be used to rank the liquid and
solid effluent streams.
4.3 ASSESSMENT OF INCREMENTAL IMPACTS DUE TO NOX CONTROLS
The program efforts described above outlined our approach for
assessing the baseline (uncontrolled for NOX) environmental impact of
30
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stationary combustion sources. This section will describe the extension of
baseline source impact rankings to include the incremental effects of
applying combustion NOX controls.
There are several reasons for describing incremental effects in
greater depth. First, a major aim of the NOX E/A is to assess the
environmental soundness of current NOX control technologies. Secondly, in
the NOX E/A, control technologies are to be ranked in order of preferred
application based largely on relative environmental and technical soundness.
Thirdly, we want to identify areas where future NOX control R&D is needed to
develop alternative or advanced control technologies to replace unsound
technologies and/or increase controllability. Finally, we want to indicate
areas where auxiliary control development is required to correct deficiencies
in current NOX technologies. To meet these goals, the incremental effects of
NOX controls on the environmental impact potential of stationary combustion
sources must be determined.
Procedures to be followed in assessing the incremental environmental
impacts from using NOX combustion controls are analogous to those described
for evaluating baseline source impacts. Thus, incremental emissions data
will be compared to MEGS through the source analysis model (developed as
described in Section 4.2) to yield controlled impact factors as a function of
the type of control and the NOX reduction achieved. Since preliminary
screening efforts indicated that available data were mostly only qualitative
(especially for noncriteria pollutants), we will rely heavily on the field
test programs to supply needed information on incremental emissions effects.
Of course, baseline emissions data obtained in these tests will be used to
refine the baseline source impact ranking.
In performing the incremental impact analysis, it is important to
realize that controlled source impact is significant only when related to
baseline impact and, ultimately, to multimedia environmental goals. For
example, a source may have small baseline impact but large relative
incremental impact for a particular NOX control. However, its controlled
environmental impact may still be small, when compared to environmental
goals. Conversely, a source with large baseline impact, but small relative
incremental effects may still prove to be significantly more harmful when
controlled for NOX.
Incremental effects will be evaluated with the source analysis model
for combustion-generated pollutants included in the baseline analyses. Thus,
more emphasis-will be placed on gaseous emissions. New pollutant species
identified through the testing programs (through Level 1 bioassays and any
subsequent Level 2 testing) will not be incorporated into the assessment
model, however, any incremental effects noted will be qualitatively treated
in the controlled impact evaluations. Similarly, secondary pollutant effects
will be evaluated only qualitatively. Nonpollutant impacts, such as noise or
thermal pollution, will only be considered superficially, since they are
generally not significantly affected by NOX combustion controls.
Incremental impacts will be assessed for the individual NOX controls
identified as major techniques in Section 8, and for commonly used combinations
of control techniques.
31
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To obtain a more complete controlled source impact evaluation, the
source analysis model/impact factor assessment described above will be extended
for selected cases by performing a set of site-specific impact analyses.
Present plans are to specify representative synthetic sites. Typical site
characteristics will be determined from knowledge gained while compiling the
baseline emission inventory, modeling baseline impact, conducting the systems
analysis, and developing AQCR scenarios. Detailed environmental impact analyses,
for an appropriate stationary combustion source at the site, will then be
performed through subcontracted effort. In general, two scenarios will be
evaluated: a baseline, uncontrolled source scenario, and a fully N0x-controlled
(using current, major technology) source scenario.
Such site-specific analyses will provide more detailed impact informa-
tion, such as more definite information on secondary pollutant impacts, and
impacts on terrestrial and aquatic life. Such information will allow greater
insight and a wider view of incremental NOX control effects.
The final step will be to rank control technologies according to
preferred application, and identify environmentally- and technically-sound
control combinations. To develop this ranking, environmental impact
evaluations will be combined with economic, operational, and fuel efficiency
impacts obtained through the process/cost calculations. The ranking will
take into account all aspects of control application. It will identify, for
a single source class, the costs of NOX control versus degree and
effectiveness of control, along with incremental environmental impacts versus
degree of control.
From this ranking it will be possible to identify research and
development needed to:
Accelerate development and demonstration of current, research-scale,
far-term controls
Increase basic research on new control concepts
Develop auxiliary controls to alleviate adverse incremental
impacts of current technology controls
This evaluation of NOX controls for single source classes is the culmination
of the process engineering studies. Issues relating to source category
ordering for control, and more global control development needs are treated
through systems analysis, described in the next section.
4.4 SYSTEMS ANALYSIS METHODS
The goal of the systems analysis is to provide a quantitative basis
for identifying the needs for future NOX controls and thereby specifying R&D
direction for developing these controls. Although the rankings of control
methods for a particular source (described in Section 4.3) are extremely
valuable, they do not provide information on when a particular control method
will be needed or on the order in which different sources should be controlled.
This information will be supplied by the systems analysis.
32
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In the systems analysis, the costs and fuel impacts for controls for
all sources are combined with predictions of air quality for a particular
AQCR to evaluate the cost and effectiveness of a control strategy. This subsection
discusses the methodology for the systems analyses: first, the development
and content of the systems analysis, then procedures for using the model.
4.4.1 Model Development
The function of the systems analysis model is to combine the various
elements that must be considered in evaluating a control strategy. These
elements include the emission levels, controls data, controls prioritization,
fuels data, and air quality predictions, as shown schematically in Figure
4-2. The evaluation of the control strategy is then made based on the cost
of the control strategy and its resulting air quality (primarily N02 concentration).
The most critical element in the system analysis model is the air
quality model. Candidate models differ not only in their degree of
sophistication, but also in their resolution and versatility. Usually, the
sophisticated models require more elaborate input data than the simpler
models, a significant amount of calibration, and considerable experience to
use them intelligently. On the other hand, the simpler models, which try to
model the atmospheric processes in an integral manner, are based on many
correlations of the available data and lack the resolution of the sophisti-
cated models.
During the first year of the NOX E/A, the systems analysis has been
used primarily for screening and preliminary prioritization of control
methods. A modified form of rollback was used to reduce the amount of emission
data needed, minimize computation costs, and provide maximum flexibility in
the initial phases of the analysis. Furthermore, only the NOX-NO? relationship
was considered, and thus, HC emissions data did not need to be collected.
The rollback model used here is given by
AC = k[ ]C (1 - Ri) EiWi I + B6
= kf ]C (1 - RI) EiWi j
where AC = ambient concentration
E.J = uncontrolled emissions from source i
R.J = reduction by control of source i
Wi = weighting factor for source i
BG = background concentration (the background concentration has been
assumed to be 10 yg/m3 for all cases)
33
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UNCONTROLLED
EMISSIONS
AIR QUALITY
MODEL
PRIORIIIZATION
OF
CONTROLS
CONTROL REQUIREMENTS
CONTROL COSTS
AMBIENT AIR QUALITY
Figure 4-2. Elements of the systems analysis model.
34
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The calibration constant, k, is determined by evaluating the equation at some
"base year" for which the ambient concentration, and emissions, are known
(Ri = 0).
Although factors such as stack height and relative position of source
and receptor are not explicitly included in the model, they are implicitly
included because the model is essentially a correlation between existing emission
patterns and the resulting ambient air conditions. Moreover, in the present
formulation it is possible to specify the relative importance of each source
type by using the weighting factors. For example, in an AQCR with a large
mixing height, emissions from elevated sources are widely dispersed and, therefore,
do not have the same impact on ground level concentration as the same amount
of ground level emissions. Thus, a source weighting factor less than 1.0 could
be assigned to the elevated sources (e.g., powerplants) to account for stack
height.*
Future program work will extend the systems analysis model to include
photochemical transport models for the air quality predictions. Including
photochemical transport will make the systems model more complex, but will
allow geographical distribution of emissions, stack height, and meteorology to
be treated directly. Both Lagrangian and Eulerian forms will be considered.
Models of this form predict 1-hour N02 and oxidant concentrations for
specific days. These short-term concentrations can be extended to annual
averages by statistical methods. Because of expense, these more sophisti-
cated models will be used only to examine selected cases. The results will
be used to validate and calibrate rollback calculations.
4.4.2 Model Application
Since the intent of the systems analysis is to guide NOX control
research activities, a wide variety of emission and ambient concentration
combinations must be considered so that the results are relevant to the
national NOX problem. In this subsection the rationale is presented for
selecting the AQCRs to be examined and for choosing the growth scenarios. In
addition, the sensitivity analysis that verifies the predictions is
described.
Although air pollution in each of the 247 Air Quality Control Regions
(AQCRs) is characterized by widely varying combinations of emissions sources
and meteorological conditions, analysis of NOX control strategies for each
AQCR is impractical and unwarranted. Therefore, the number of AQCRs to be
considered was reduced as follows:
t Identify air pollution characteristics, including meteorology,
emissions, ambient air quality levels, and data availability
*Each choice of weighting factors is equivalent to choosing a different model
for the AQCR. In all cases the model must be calibrated for the base year
(calculate k) before future year projections are made.
35
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Group AQCRs according to these air pollution characteristics
t Select one AQCR to represent each group for further analysis
The group of AQCRs to be considered was limited to those which have, or are
expected to have, a NOX problem between now and the year 2000. Each of these
regions belongs to one of the following groups:
Priority AQCRs AQCRs with ambient N02 concentrations currently
exceeding the N02 standard when averaged over any consecutive four
quarters (i.e., a rolling quarter basis rather than the statutory
calendar year basis)
Air Quality Maintenance Areas (AQMAs) Regions with a high
probability of exceeding the standard by 1985
OAQPS has identified 30 regions which fall into these two categories
(Reference 21). Although using the "rolling-quarter" method will place more
regions into the priority category, it has the advantage of providing a
conservative approach to identifying potential control requirements and is
consistent with OAQPS thinking.
The air pollution characteristics of each AQCR for grouping purposes
included: mobile versus stationary source emissions distribution, fuel type
which produces the majority of stationary source NOX emissions, dominant
stationary source type, HC/NOX emission ratio, ambient oxidant and NOX
levels, solar insolation, stability class, and quality and detail of
available emissions data. Data for each of these properties are shown in
Table 4-1 for the 30 NOg-sensitive AQCRs identified by OAQPS. Three
unsuccessful attempts were made to divide the AQCRs into distinctive
groupings: the first sought a relationship between high mobile emissions and
high NOX/HC ratios; the second a correspondence between a high HC/NOX ratio,
a high ozone level, and a high solar insolation level; and the third a
relation between high mobile emissions and high ozone levels. None of these
attempts produced significant correlations. However, correlations were
obtained when the regions were separated into the four groups shown in Table
4-2. The criteria for this grouping were the mobile/stationary source mix,
the major stationary source type (utility or industrial), and the major fuel
type responsible for NOX emissions. All of these factors directly affect
selecting the most suitable control methods for reducing NOX emissions
effectively.
The preliminary screening of control technologies considered only Los
Angeles and Chicago. These are logical choices for a limited analysis, since
they are the two most N0x-critical AQCRs in the country (see Table 4-1) and
they represent two opposite categories ~ one is mobile source dominated, the
other is stationary source dominated. St. Louis and New York City may be
assessed in subsequent analyses.
36
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TABLE 4-1. AIR POLLUTION CHARACTERISTICS OF THE NOX IMPACTED AQCRs AND
AQMAs
City
Los Angeles
Chicago
Philadelphia
Canton
San Diego
Bal timore
Detroit
Salt Lake City
Springfield
New York City
Denver
Richmond
Phoenix
San Francisco
Boston
Atlanta
Louisville
St. Louis
Cincinnati
Lansing
Dayton
New Orleans
Minneapolis
Steubenvllle
Memphis
Charleston, U. Va.
Milwaukee
Washington. D.C.
Pittsburgh
Youngstown
AQCR
Number
24
67
45
174
29
115
123
220
42
43
36
225
15
30
119
56
78
70
79
122
173
106
131
181
18
234
239
47
197
178
Mobile
Statlonarya
(X)
66.0-M
63.9-S
54.8-S
56.4-S
70.1-M
58.9-M
52.5-S
54.3-M
54.0-M
61.2-S
54.3-M
66.0-S
76.1-M
70.4-M
53.5-S
55.2-M
78.9-S
75.0-S
S6.8-S
64.3-S
57.3-M
77.0-S
57.5-S
90.1-S
58. 2- S
38.4-S
53.3-S
55.0-M
77.1-S
53.6-S
Dominant
Fuelb
(X)
38-G
42-C
53-0
80-C
54-G
61-0
62-C
33-G
66-0
82-0
58-C
62-0
70-G
42-0
94-0
52-C
85-C
72-C
79-C
47-C
67-C
54-G
55-C
63-C
64-C
95-C
63-C
48-0
90-C
7T-C
Station-
ary Com-
bustion0
(X)
72. -U
56. -U
55.6-U
55.6-U
78.4-U
63.9-U
65. -U
58.7-1
5S.3-U
56.3-U
45.3-1
68.8-U
72.7-U
43.5-U
48.6-U
77.0-U
80.6-U
88.3-U
69.9-U
95.3-1
51.9-U
67.0-1
75.4-U
62.8-U
77.4-U
94.7-U
69.5-U
71.5-U
83.4-U
63.6-U
61 f ford
Pasqulll
Sta-
bility
Classd
45S-D
58J-E
46J-D
49VD
66%-D
481-0
51X-D
4U-D
46S-D
46S-E
56S-D
7M-D
46X-D
511-D
57I-D
_
57X-D
391-D
591-D
47X-0
48X-D
65S-D
51S-D
66S-D
63S-D
HC/HOX
Ratio
1.649
1.071
1.142
1.438
1.678
1.805
1.340
0.917
1.308
0.975
0.987
0.917
1.604
1.471
1.348
1.122
0.843
0.615
0.972
0.966
1.373
1.171
0.632
0.139
0.801
0.199
2.519
1.052
0.416
0.855
NO?.
182
121
121
120
119
116
115
114
113
113
110
103
101
101
100
100
96
85
83
90
90
83
84
98
81
85
81
80
98
96
1 Hour
(yg/Bi5)
376
193
157
95
189
66
115
99
341
211
176
181
117
163
175
157
122
250
118
226
136
190
107
127
180
199
226
Solar
Insolation*
H
L
L
L
H
M
L
M
L
L
M
M
H
M
L
M
M
M
M
L
L
M
M
L
M
M
L
M
L
L
*M - Mobile
S - Stationary
Dominant source of NOX by fuel type, X of stationary source NOX emissions
e - Natural Gas
0-011
C-Coal
Sj - Utility
I - Industrial
*rhese values represent the percent occurrence of the dominant stability class trlthln each AQCR.
eBas1n average of 99 percentlle Measurements
Average dally solar Insolation:
H > 16.7 MJ/mz
M > 12.5 MJ/m2
L < 12.5 MO/m2
37
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TABLE 4-2. CHARACTERISTIC GROUPS OF NOX IMPACTED AQCRs and AQMAs
1. Stationary - Oil - Utility
New York City
Richmond
Boston
Philadelphia
2. Stationary - Coal - Utility
St. Louis
Louisville
Cincinnati
Minneapolis
Steubenville
Memphis
Charleston
Lansing"
Pittsburg
Youngstown
3. Stationary - Coal - Utility
Chicago
Canton
Detroit
Milwaukee
4. Mobile
Los Angeles
San Diego
Bal timore
Salt Lake City
Springfield
Denver
Phoenix
San Francisco
Atlanta
Dayton
Washington
N0xa
H
H
H
H
M
M
M
M
M
M
M
M
M
M
H
H
H
M
H
H
H
H
H
H
H
H
H
H
H
HC/NOxb
H
H
H
H
M
M
H
M
L
M
L
H
L
M
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Ozone0
M
L
L
L
M
L
L
L
L
L
L
L
L
L
L
H
L
L
L
H
M
L
L
L
M
L
"High: NOX >. 100 yg/m3; Medium: NOX < 100 yg/m3.
bHigh: HC/NOX > 0.9; Medium: 0.45 < HC/NOX <. 0.9; Low: HC/NOX <. 0.45.
cHtgh: 300 <_Ozone < 400 yg/m3; Medium: 200 <. Ozone < 300 yg/m3;
Low: 100 <_Ozone < 200 yg/m3.
Lansing is shown in Table 7-3 to be industrial dominated. Since no utility
emissions were reported, it was decided to place Lansing in Group 2.
38
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Once an AQCR has been selected for analysis, its base year emissions
must be projected to a future year. The choice of scenarios for projecting
growth may heavily influence the control levels required. We have selected
scenarios that represent reasonable bounds for both mobile and stationary
source growth. Generally, growth rates apply to an end-use sector, such as
industrial or residential; however, in this analysis they have been extended
to each source within the sector. Whenever possible, growth rates specific
to an AQCR are used. If specific AQCR rates are not available, state, re-
gional or national rates are used. In addition, the influence of population
growth and any local limitation on new source growth are considered. Two
basic scenarios were selected for stationary sources. One case represents
a moderately conservative growth influenced by conservation measures and rising
energy costs, and is reasonably likely to occur. The other represents a higher
growth rate closer to historical patterns. This case represents a reasonable
upper bound on stationary source growth.
The growth rates of emissions from mobile sources were treated
differently, since a detailed investigation of mobile source control options
is not of direct interest to this study. However, the emissions
contributions of the mobile sources were needed, thus two representative sce-
narios were used. One scenario (the nominal case) was selected to reflect
historical growth in vehicle population and miles traveled, as well as a
moderate emission standard. The alternate, or low, case was for a reduced
growth rate (closer to the population growth rate) and an emission standard
of 0.25 g/km.
The last step in the methodology is a sensitivity analysis that
establishes the sensitivity of the systems analysis results to the various
assumptions and input data. Part of the sensitivity can be accounted for by
considering several AQCRs and growth scenarios, as discussed above. This
ensures that the predicted NOX control levels will be responsive to the ma-
jority of N0x-critical situations which may develop in the future.
Other factors must also be considered, though. One is the choice of
the air quality model. The two models discussed in Section 4.4.1 source
weighted rollback and photochemical transport are very different in terms
of complexity and level of physical detail. A second sensitivity
consideration is in the choice of parameters used within the air quality
model. As was mentioned in Section 4.4.1, source weighting factors in
modified rollback models can be used to examine the sensitivity of the
results to the weighting of each source. For the photochemical models, the
sensitivity of the results to the initial ambient concentrations and meteo-
rology must be considered. For both the rollback and photochemical models,
the sensitivity to the base year calibration of the model also must be
examined. A change in the base year calibration has the same effect as
choosing a different growth scenario. These factors were considered in
applying the systems model.
Applying the systems model to the selected AQCRs, including a variety
of growth scenarios and model sensitivities, results in a range of control
requirements for meeting future air quality goals. The requirements include
the level of control necessary for the various sources, the time frame for
39
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applying these controls, and which controls are the most cost-effective.
Specific results to date are presented in Section 8.
40
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SECTION 5
CONTROL TECHNOLOGY BACKGROUND
The control technology assessment in the NOX E/A will compile and
evaluate process data to provide environmental assessments of combustion
modification control technologies. The overall objectives of the assessment
are to:
Characterize current and advanced NOX combustion process modifications
and project schedules for applying them
t Assess the technical and environmental soundness of these control
technologies
Recommend R&D for filling in technological gaps and producing needed
data
Provide objective evaluations of important aspects of NOX control
systems
The results will be documented in a series of reports covering the seven
major stationary source equipment categories.
The main efforts to date have involved characterization and
preliminary assessment of NOX combustion modification control technology.
This assessment identified the source/control combinations most likely to be
used widely in the near future and projected the effectiveness, cost, and
schedule of advanced emerging techniques being developed. The results were
used to determine the source/control priorities of both near- and far-term
control applications for the seven main equipment categories. The results
from the preliminary assessment are summarized in the following subsections.
5.1 STATUS AND PROSPECTS OF CONTROL REQUIREMENTS
The incentive for developing NOX controls derives from two separate
regulatory mechanisms: the Federal Standards of Performance for New
Stationary Sources (NSPS) and the State Implementation Plans (SIPS). The
NSPS are intended largely to assist in maintaining air quality by offsetting
increases due to source growth. EPA sets NSPS from time to time, based on
the best systems of reducing emissions. Part of the effort to develop
NOX controls is directed at developing and demonstrating the best systems of
41
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reducing emissions in support of the setting of future NSPS. The primary
responsibility for attaining and maintaining air quality rests with the
states. If emission standards in addition to the NSPS are required to attain
and/or maintain the National Ambient Air Quality Standards in Air Quality
Control Regions within the jurisdiction of the states, these standards are
set through SIPS. Therefore, another part of the effort to develop NOX
controls is directed at facilitating compliance with these standards.
All Federal, state, and local standards for NOX -- both current and
impending ~ are based on combustion process modifications. To date, Federal
NOX standards have been set only for utility and large industrial boilers.
These standards have been based largely on demonstrated technology
retrofitted to sources in areas with attainment problems. A more stringent
standard is being considered for coal-fired utility boilers, based on
technology demonstrated since 1971. However, revised, more stringent
standards are not being considered for new gas- or oil-fired utility boilers,
since no units of this type are being sold. The Federal standard recently
proposed for gas turbines is also based on retrofit technology demonstrated
as part of SIPS. Federal standards under study for 1C engines and industrial
boilers are being based on EPA and private sector control development since
there have been few retrofit controls used on these sources.
Maintaining air quality in the 1980's and 1990's may require Federal
NOX regulations in addition to those existing or planned. New source
controls will be emphasized, since experience has shown them to be more
effective, less costly, and less disruptive than retrofitting controls on
existing equipment. Thus, EPA's Office of Air Quality Planning and Standards
anticipates additions to the existing Federal standards. These additions may
include standards for sources not presently regulated, as well as more
stringent standards for sources with current or impending controls.
5.2 COMBUSTION PROCESS MODIFICATION TECHNOLOGY
As a result of emission control regulations for new and existing
stationary sources, NOX control techniques have been developed and
implemented in the past 10 years. Nearly all current NOX control applications
use combustion process modifications. Other approaches, such as modifying
or switching fuels, using alternate energy systems, and treating post-combustion
flue gas, as well as more advanced combustion process modifications are being
evaluated for potential future use. Experience has shown that the applicability
and effectiveness of combustion process modifications depend on the specific
equipment/fuel combination to be controlled, and on whether the control is
to be applied to existing field equipment or new units. Accordingly, control
development is focusing on specific equipment categories and fuel types.
In general, the following sequence of control development is being pursued
for each major equipment/fuel category:
t Minor operational adjustments
Minor retrofit modifications
42
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Extensive hardware changes, either retrofit or factory-installed on new
units of conventional design
Major redesign of new equipment
Progress made in this sequence varies with the importance of the source in
local and national NOX regulatory strategies.
Currently, modifying combustion process conditions is the most
effective and widely-used technique for achieving 20- to 70-percent reduction
in combustion-generated oxides of nitrogen. These modifications include:
Low excess air firing
t Flue gas recirculation
§ Off-stoichiometric combustion
Load reduction
Burner modifications
t Water injection
Reduced air preheat
Ammonia injection
The following paragraphs summarize the status of each of these controls.
Low Excess Air Firing
Changing the overall fuel-air ratio is a simple, feasible, and
effective technique for controlling NOX emissions from all stationary sources
of combustion except gas turbines. For some sources, such as utility
boilers, low excess air (LEA) firing is currently a routine operating
procedure and is incorporated in all new units. Since it is energy efficient
and easy to implement, LEA firing will be increasingly used in other sources.
However, most sources will have to use other control methods, in conjunction
with LEA, to meet NOX emissions standards. In such cases, the extent to
which excess air can be lowered will depend upon the other control techniques
employed. Virtually all programs for developing advanced NOX controls are
emphasizing operating at minimum levels of excess air. Thus, LEA will be an
integral part of nearly all combustion modification NOX controls, both
current and emerging, to be assessed in the NOX E/A.
Flue Gas Recirculation
The primary near-term application of flue gas recirculation (FGR) is
in gas- and oil-fired utility boilers. Future applications are limited. FGR
may be used in industrial boilers as a retrofit or in new designs, but
43
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alternate approaches, such as low-NOx burners and off-stoichiometric
combustion, also are being evaluated and may prove more attractive.
Techniques other than FGR are more effective for coal-fired utility boilers,
gas turbines, and warm air furnaces. The effectiveness of FGR with process
furnaces is under evaluation.
Off-Stoichiometric Combustion
Off-stoichiometric combustion (OSC) is a widely used technique for
controlling thermal and fuel NOX from large boilers. Near-term uses of OSC
to be considered in the NOX E/A include retrofitting on gas-, oil- and coal-
fired utility boilers and using factory-installed equipment on new coal-fired
utility boilers. Potential future applications to be considered include
using factory installations on new industrial boilers and using advanced
staging techniques for major redesigns of utility or industrial boilers.
Load Reduction
Load reduction/enlarged firebox techniques may be used in the near
term as retrofits to gas- and oil-fired utility boilers and as new designs
for coal-fired utility boilers. Load reduction also may be used on new and
existing industrial boilers as standards are set. Because of economic and
operational penalties, load reduction for existing boilers is unattractive,
and is used only as a last resort to achieve compliance with standards.
Burner Modifications
New, optimized-design burners appear to be capable of reducing NOX
emissions 40 to 65 percent with gas and oil fuels. Similar, or greater,
reductions are being demonstrated on prototype coal-fired units. The new
low-NOx burners are designed to mix fuel and air in a controlled pattern that
sustains local fuel-rich regions, keeps the flame temperature down, and
dissipates the heat quickly. Improved burner designs may well replace the
external combustion modifications now in use and produce significantly lower
NOX emissions. Thus, although low-NOx burners have limited use currently,
they will be emphasized in the NOX E/A for both near- and far-term application.
Water Injection
Water injection has been found to be effective in suppressing NOX
emissions from gas turbines and 1C engines. However, water injection may
decrease thermal efficiency, increase equipment corrosion, and cause
other undesirable operating conditions. Therefore, it is anticipated that
water injection will be replaced by advanced combustor design in the long
term.
44
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Reduced Air Preheat
Reduced air preheat for gas turbines and for boilers is not a
practical way to control NOX unless the energy in the exhaust gases can be
used effectively for other purposes, such as in combined gas-steam turbine
cycles. Reduced air preheat will thus be accorded low priority in the NOX
E/A because of associated efficiency losses.
Ammonia Injection
Ammonia injection does not appear to have significant near-term
application for NOX control in the U.S. However, it shows promise for far-
term applications and will be given primary emphasis in the NOX E/A for
assessment of advanced concepts for the 1980's and 1990's.
5.3 ALTERNATE CONTROL TECHNIQUES
In addition to combustion modifications, NOX can be controlled by one
or more of the following techniques: flue gas treatment, fuel
denitrification, fuel additives, alternate or mixed fuels, or advanced, low-
NOX combustion concepts. Each of these is briefly discussed below.
Flue Gas Treatment
The dry flue gas treatment (F6T) techniques used in Japan -- notably
selective catalytic reduction with ammonia ~ can probably be applied to
gas- and oil-fired sources in the U.S. However, more pilot and full scale
demonstration tests are needed before full application of dry processes is
possible on these sources. Dry processes have yet to be demonstrated on coal-
fired sources, although pilot-scale tests are currently planned. Wet processes
are less well developed and more costly than dry FGT processes; however, wet
processes have the potential to remove NOX and SOX simultaneously. Again,
pilot-scale research and field tests are needed to determine costs, secondary
effects, reliability, and waste disposal problems. Flue gas treatment holds
some promise as a control technique if very stringent emissions standards
make it necessary to greatly reduce NOX. However, even in these instances FGT
will probably be employed to supplement combustion modification.
Fuel Denitrification
Fuel denitrification of coal or heavy oils could, in principle, be
used to control the component of NOX emissions produced by the conversion
of fuel-bound nitrogen. The most likely use of fuel denitrification would
be to supplement combustion modifications that reduce thermal NOX. Currently
denitrification occurs only as a side effect of pretreating fuel to remove
sulfur, ash, or other pollutant precursors. Preliminary data indicate that
30- to 40-percent reductions in fuel nitrogen result from oil desulfurization
(Reference 22). Since these processes produce low denitrification efficiencies,
45
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they are not attractive solely for controlling NOX- However, they may prove
cost effective in terms of their total environmental impact.
Fuel Additives
Results of recent studies on fuel additives for NOX control have been
mixed. In some cases, additives significantly reduced NO emissions, while in
other studies they did not. Overall, using additives for controlling NOX is
not attractive since they add to cost, cause serious operational difficulties
and may lead to other flue gas pollutants. However, it has been proposed
that some fuel additives may provide a peripheral benefit, by allowing
increased flexibility in using combustion modification techniques.
Alternate or Mixed Fuels
Using alternate or mixed fuels to control NOX is contingent in part on
the trade-off between the costs of producing synthetic fuel and the total
costs of controlling NOX, SOX and particulates in conventional coal firing.
There is preliminary evidence that gasification may be more costly than flue
gas cleaning of conventional utility systems (Reference 23).
Advanced Combustion Concepts
For new combustion systems, the combustion control technology derived
from retrofitting existing units can be incorporated with new concepts not
applicable for retrofit into designs optimized for low-NOv production. This
approach produces designs that potentially lower costs and are more effective
than extensive retrofitting of existing units. Alternatively, the economics
of using lower quality fuels necessitated by the clean fuels shortage may
dictate using alternate combustion process concepts. Some concepts, such as
catalytic combustion, fluidized bed combustion, and gasifier combined cycles,
are being developed for their potential not only to increase system
efficiency, but also to reduce total system emissions. Other alternate
concepts, such as repowering and high-temperature gas turbines, are being
developed mainly to increase the efficiency of current technology to reduce
fuel consumption.
5.4 OVERALL EVALUATION AND CONCLUSIONS
The results of characterizing current and emerging control technology
for the major equipment categories, briefly discussed above, are summarized
in Table 5-1. These results show that both current and emerging technologies
are also centered around combustion modifications. Other approaches, such as
flue gas treatment, may be used in the 1980's in addition to combustion
modification if required by more stringent emissions standards.
The level of combustion modification control currently available for
a given source depends on the importance of that source in the regulatory
program. Utility boilers have been the most extensively regulated and
46
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TABLE 5-1.
SUMMARY OF NOX CONTROL TECHNOLOGY
Equipment/
Fuel
Category
Existing coal-
flred utility
boilers
New coal -fired
utility
boilers
Existing oil-
fired
utility
boilers
Existing
gas-fired
utility
boilers
Oil-fired
Industrial
water tube
boilers
Current Technology
Available
Control
Technique
LEA + OSC
(OFA, BOOS,
BBF); new
burners
LEA + OFA;
new
burners
LEA + OSC
+ FGR;
load re-
duction
LEA + OSC
+ FGR;
load re-
duction
LEA + OSC
(OFA,
BOOS,
BBF)
Achievable
NOX Emission
Level ng/J
(lb/10' Btu)
260-300
(0.6 - 0.7)
215-260
(0.5 - 0.6)
110-150
(0.25 - 0.35)
65-85
(0.15 - 0.2)
85-130
(0.2 - 0.3)
Estimated
Differential
Annual Cost
20-30t/kW
10-20t/kW
$1-2/kU
$l-2/kW
7-9*/ ,
(kg/hr)a
Operational
Impact
Possible
Increase In
corrosion &
slagging &
carbon 1n
flyash
No major
problem with
tangential
design;
other
designs now
coming
online
Possible
flame
Instability;
boiler vi-
bration
Possible
flame
instability;
boiler vi-
bration
-IX Increase
in fuel con-
sumption;
flame insta-
bility;
boiler vi-
bration
(retrofit)
Emerging Technology
Near Term
1977-1982
Advanced low
NOX burners
Low NOX
burners ad-
vanced stag-
Ing concepts
Low NOX
burners;
oil denltrl-
fi cation
Low NOX
burner
Low NOX
burners; OFA
in new unit
designs; oil
denitrifi ca-
tion
Far Term
1983-2000
Ammonia
Injection;
flue gas
treatment
Optimized burner
firebox design;
fluldlzed bed
combustion;
ammonia Injec-
tion
Amnonia Injec-
tion; flue gas
treatment
Ammonia Injec-
tion; flue gas
treatment
Optimized
burner/firebox
design;
ammonia
injection
Comments
Ammonia Injection,
FGT potential
supplement to CM If
needed
Same as above
No new units;
emission levels are
limit of current
technology
No new units; emission
levels are limit of
current technology
Current technology
still being
developed
in
m
-------
TABLE 5-1. CONTINUED
Equipment/
Fuel
Category
Stoker-fired
Industrial
watertube
boilers
Gas-fired
Industrial
watertube
boilers
Industrial
flretube
boilers
Gas turbines
Current Technology
Available
Control
Technique
LEA + OFA
LEA + OSC
(OFA. BOOS,
BBF)
LEA + F6R;
LEA + OSC
Hater,
steaa
Injection
Achievable
NOX Emission
Level ng/J
(lb/10* Btu)
150-190
(0.35 - 0.45)
86-130
(0.2 - 0.3)
65-110
(0.15 - 0.25)
110-150
(0.25 - 0.35)
Estimated
Differential
Annual Cost
9-1U .
(kg/hr)a
7-9*/ .
(kg/hr)a
30-65*/
(kg/hr)a
$l-2/kH
Operational
Impact
Possible
-IX Increase
In fuel con-
sumption;
corrosion;
slagging of
grate
(retrofit)
-IX Increase
In fuel con-
sumption;
flame
Instability;
boiler vi-
bration
(retrofit)
-IX Increase
In fuel con-
sumption;
flame Insta-
bility
(retrofit)
-IX Increase
In fuel con-
sumption;
affects only
thermal
Emerging Technology
Near Term
1977-1982
Inclusion of
OFA In new
unit design
Low NOv bur-
ners; OFA In
new unit
design
Low NOX burn-
ers; OFA or
FGR In new
unit design
Advanced corn-
bus tor de-
signs for
dry NOX con-
trols
Far Term
1983-2000
Fluldlzed bed
combustion;
ammonia
Injection
Optimized
burner/firebox
design; ammonia
Injection
Optimized
burner/firebox
design
Catalytic com-
bustion; ad-
vanced can
designs
Comments
Current technology
still being
developed
Current technology
still undergoing
development
Development continuing
on current technology
Current technology
widely used
-------
TABLE 5-1. Concluded
Equipment/
Fuel
Category
Residential
furnaces
1C engines
Industrial
process
furnaces
Current Technology
Available
Control
Technique
Low NO.
burner?
firebox
design
(oil)
Fine
tuning;
changing
A/F
LEA
Achievable
NOX Emission
Level ng/0
(lb/10* Btu)
25-40
(0.06 - 0.1)
1 ,070-1 ,290
(2.5 - 3.0)
85-210
(0.2 - 0.5)
Estimated
Differential
Annual Cost
$0.14-0.29/
kH
($40-80/(MBtu/
hr))
$0.70-2.00/kW
($0.5-1. 5/
BHP)
Unknown
Operational
Impact
~5X decrease
1n fuel con-
sumption
5-1W In-
crease In
fuel con-
sumption;
misfiring;
poor load
response
Unknown
Emerging Technology
Near Term
1977-1982
Advanced
burner/fire-
box design
(gas & oil)
Include mod-
erate con-
trol 1n new
unit design
Low NOX
burners;
development
of external
controls
(FGR, OSC)
on retrofit
basis
Far Term
1983-2000
Catalytic
combustion
Advanced head
designs, exhaust
gas treatment
Possible Inclu-
sion In new
unit design
Comments
Current technology
still being tested
Technology still being
tested
Control development
1n preliminary stages
a
in
U)
H-
kg/hr steam produced
-------
accordingly, control technology for these boilers is the most advanced.
Available technology ranges from operational adjustments, such as low excess
air and biased-burner firing, to including overfire air ports or low-NOx
burners in new units. Some adverse impacts on operation have been
experienced when combustion modifications have been used on existing
equipment. In general, these problems have been solved by combustion
engineering or by limiting the degree to which controls are used. Factory-
installed controls on new equipment have produced only minimal operational
problems.
Technology for other sources is less well developed. Control
techniques effective for utility boilers are being demonstrated on existing
industrial boilers. Here, as for utility boilers, the emphasis in emerging
technology is on developing controls for new unit designs. Advanced low-NOx
burners and/or advanced off-stoichiometric combustion techniques are the most
promising concepts for these boilers and for the other source categories as
well. The R&D emphasis for gas turbines, warm air furnaces, and
reciprocating 1C engines is on developing optimized combustion chamber
designs matched to the burner or fuel/air delivery system. Control
development for the different types of industrial process equipment is in the
preliminary stages and to date, only minor operational adjustments have
been tried.
Continuing program efforts in the NOX E/A will seek to extend and
strengthen the background data for NOX control process technology assembled to
date. Emphasis will be given to tracking ongoing demonstration and testing
of near-term control techniques, as well as to following the development of
advanced controls and alternate combustion concepts.
50
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SECTION 6
CONTROL TECHNOLOGY ASSESSMENT
A primary aim of the NOX E/A program is to extend the process technol-
ogy background discussed in Section 5 to include evaluations of the emissions
and source performance impacts associated with applying these controls. In
this respect the initial process data compilation serves to set the stage for
further assessment efforts. This section discusses the NOX E/A approach and
efforts to perform more definitive control technology evaluations.
6.1 PROCESS ENGINEERING APPROACH
Evaluating the impacts of NOX combustion modification controls applied
to stationary combustion sources requires assessing their effects on both
controlled source performance, especially as translated into changes in
operating costs and energy consumption, and on incremental emissions of
pollutants other than NOX. To perform such an evaluation it is necessary to:
Relate the application of preferred (major) NOX controls to changes
in multimedia pollutant emissions through the primary combustion
parameters affected by applying controls
Relate the application of preferred NOX controls to demonstrated
or expected impacts on controlled source operations and performance
through the same parameters
Estimate the capital and operating costs, including energy impacts
of implementing NOX control
It is desirable to use a standard format for these evaluations because
it alljows uniform comparisons to be made among various control strategies
applied to different equipment items within a source category. Therefore,
the NOX E/A will stress developing a standard process calculation structure,
which describes the kind and level of detail of process design-type
calculations to be performed; and a set of standard cost calculation
procedures, which specifies economic bases and cost evaluation assumptions.
Once.these are established, performing process/cost calculations for NOX control
application is conceptually straightforward. The control costs, operational
impacts, and multimedia emissions versus degree of control for NOX controls,
applied singly and in combination, can be determined from these calculations.
51
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The program plan developed for performing control process engineering
and impact evaluations is shown schematically in Figure 6-1. Heavy reliance
on initially establishing detailed calculation procedures is indicated.
Brief subtask descriptions are given below.
As noted, the process procedures subtask outlines in detail the
process engineering methodology to be adopted and the calculation structure
to be used. Key elements include: establishing the set of base case source
items (major design type/fuel combinations) to treat, establishing the level
and detail of heat and material balances to perform, developing the
calculation algorithms to use in performing these heat and material balances,
specifying the matrix of calculations to perform, and defining methods to
assess operation and maintenance impacts. Similarly, specifying cost
calculations procedures includes: establishing the check list of cost items
to consider, establishing the cost reporting basis, specifying the parameters
required in the cost reporting scheme, (interest rates, tax procedures,
depreciation, fuel cost escalation, etc.), specifying assumptions required to
establish maintenance, developmental, and shakedown costs, and formulating
cost calculation algorithms to interface with process calculations.
Data compilation efforts assemble and correlate process operation
data, multimedia emissions, and cost information needed for performing the
process/cost calculations. The control application design task involves the
actual engineering design required to retrofit a standard field unit (e.g.,
boiler) to incorporate selected NOX control techniques. Such designs will be
performed to aid in defining precise capital equipment cost data for major
control applications.
Once the calculational and evaluation procedures are well defined, and
all requisite data assembled and standardized, process/cost calculations will
be performed for baseline and selected NOX control technique applications.
The matrix of calculations performed will define the cost versus degree of
NOX control curves for the set of standard equipment items treated. Results
from the calculations will help identify potential operational and
performance impacts. Incremental emission effects and interactive effects of
using combined control techniques will also be noted.
The results of the process/cost calculations are input to the impact
assessment subtask. Overall control impact evaluation and preferred control
technique ranking will be performed in this subtask, as discussed in Section
4.3.
This process engineering treatment will be done only for source/
control combinations identified for major program emphasis in Section 8.
Minor source/control combinations will be investigated less rigorously
and more qualitatively through the minor source/control subtask shown in
Figure 6-1.
6.2 PROCESS ENGINEERING METHODOLOGY
Program efforts to date have focused on developing procedures and
compiling data for treating utility boilers (the first source class to be
52
-------
Establish Process
Calculation Procedures
Process Technology
Background
Compile Process and
Cost Data
en
CO
Design Control
Application
Establish Cost
Calculation Procedures
Perform Process/
Cost Calculations
Treat Minor
Sources and Controls
Assess Control
Impacts
Figure 6-1. Process engineering -- subtask flowsheet.
-------
evaluated as discussed in Section 8). In developing process calculation
procedures, effort has concentrated on relating flue gas pollutant emission
levels and indications of boiler performance to fundamental boiler design and
operating parameters.
Stepwise linear regression analysis will be used, where possible, to
correlate flue gas pollutant emissions to such variables as percent
stoichiometry at the burners, volumetric heat release, surface heat release,
and percent nitrogen in the fuel. Field test data assembled so far suggest
that good correlations for NOX emissions may be possible. Incremental
emissions, especially noncriteria pollutants and trace species, will probably
have to be assessed more qualitatively.
Boiler heat and material balances, supplemented by fundamental
combustion theory and knowledge of boiler operation practice, will be used to
help predict potential operational and maintenance related problems. For
example, the altered boiler temperature profile resulting from firing burners
out of service generally places extra demands on the superheater
attemperation equipment. If installed capacity is insufficient, the boiler
must be derated. Similarly, the higher levels of overall excess air
generally required to prevent combustibles losses when firing burners out of
service may exceed forced draft fan capacity. Again, the boiler may have to
be derated. Such potential problems can conceptually be related to changes
in the heat and material balance. Current efforts have been directed toward
researching these relationships.
Process and emissions data on coal-fired tangential boilers have been
the most complete assembled so far. Therefore, current process engineering
has concentrated on this design type, fuel combination. Plans are to also
treat oil- and gas-fired tangential boilers, and horizontally opposed and
wall-fired design types firing coal, oil, and gas, in as much detail as
available data allow. Emphasis will be placed on coal- and oil-fired
equipment.
Standard boiler configurations will be identified from Federal Power
Commission data stored in the EPA Energy Data System file. Emissions data
from past field test programs have been assembled and are currently being
organized and evaluated for sufficiency. Data from ongoing programs will
continually be incorporated. Process data on other than tangential boilers
have been sketchy. Continuing efforts to assemble such data from
manufacturers, utilities, and subcontractors are proceeding.
In developing cost procedures for utility boilers, effort has
concentrated on establishing the cost reporting basis and the set of cost
items to consider. Cost calculations will be performed on an annualized unit
cost basis using regulated utility economics. Items to be considered in ad-
dition to capital equipment and installation costs, and energy costs of
operation include:
Engineering and development cost estimates as a fraction of capital
i nvestment
a Startup and shakedown costs as a fraction of capital investment
54
-------
Maintenance costs as a fraction of capital investment
Debt/equity financing of capital investment
0 Taxes
Fuel cost escalation
t Purchased power costs when the boiler is derated
Capital equipment cost estimates will follow from design efforts and
will be supplemented by utility experience where data are available.
Appropriate assumptions for development, maintenance, and shakedown costs
will be based on user experience where possible.
55
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SECTION 7
ENVIRONMENTAL DATA ACQUISITION
This section summarizes the assembling and organizing of multimedia
emission data required to perform the NO,, environmental assessment. The
results of a baseline stationary combustion source emissions inventory
and the extension of that inventory to include the incremental emission
effects of NOX combustion controls are presented in the following subsections,
Since, in many cases, data were insufficient, tests will be initiated
to resolve the gaps. These tests are described in Section 7.3.
7.1 BASELINE EMISSIONS INVENTORY
A baseline multimedia emissions inventory was produced for all
significant stationary NOX sources. This inventory was then extended to
include all other sources of NOX (mobile, noncombustion, fugitive) to
compare emissions from stationary combustion sources with those from other
sources. Multimedia pollutants inventoried included the criteria pollutants
(NOX, SOX, CO, HC, particulates), sulfates, polycyclic organic matter
(ROMs), trace metals, and liquid and solid effluents.
This inventory will guide subsequent NOX E/A research by providing
a base for weighing the incremental emissions impact from using NOX controls.
The inventory also serves as the reference for projections to the year
2000 for anticipated trends in fuels, equipment, and stationary source
emissions. In addition, data gaps identified in compiling the emission
factors highlight areas where further testing is needed in the NOX E/A
or other programs.
The emissions inventory was performed in the following sequence:
Compile fuel consumption data for the categories of combustion
sources specified in Section 2. Subdivide fuel consumption data
based on fuel-bound pollutant precursor composition.
Compile multimedia emission data
Base fuel-dependent pollutant emission factors on the trace
composition of fuels
57
-------
Base combustion-dependent pollutant emission factors on
unit fuel consumption for specific equipment designs
Survey the degree to which NOX, SOX, particulates are controlled
t Produce emissions inventory
Rank sources according to emission rates; compare the ranking to
results of previous inventories
Although detailed breakdowns of fuel consumption, emission factors,
and total emissions for each equipment/fuel combination were developed, only
emission totals for each sector will be summarized here.
The distribution of anthropogenic NOX emissions is shown on Figure
7-1 for the year 1974, the most recent year for which complete fuel consumption
data are available. The estimates of utility boiler emissions account
for the reduction resulting from using NOX controls. From a survey of
boilers in areas with NOX emission regulations, it was estimated that
using NOX controls in 19/4 resulted in a 3.1-percent reduction in nationwide
utility boiler emissions. This corresponds to a 1.6-percent reduction
in stationary fuel combustion emissions. Reductions from using controls
on other sources were negligible in 1974.
In general, the total NOX emissions from stationary sources and
the distribution of these emissions among equipment types for 1974 show
little change compared to 1972 inventories (Reference 24). The current
inventory also shows generally good agreement with recent inventories
conducted by EPA's Office of Air Quality Planning and Standards and other
groups (References 25 through 27). One exception is for industrial packaged
boilers. Here, recent estimates differ by as much as a factor of 2, primarily
because total fuel consumption is uncertain for this sector.
The emission inventory results for other pollutants are shown in
Table 7-1. Data for the criteria pollutants were generally good and the
results of these current inventories are in reasonable agreement with
other recent inventories. Data for the noncriteria pollutants and liquid
or solid effluent streams, however, were sparse and scattered. For example,
emission factors for POMs varied by as much as two orders of magnitude;
Table 7-1 shows the range for total POM emissions. Several ongoing field
test programs are sampling noncriteria pollutants. The current inventory
will be updated with these results before emissions impacts are assessed
as described in Section 4.2.
Table 7-2 ranks equipment/fuel combinations by annual, nationwide
NOX emissions, and lists corresponding rankings for these combinations
by fuel consumption and emissions of criteria pollutants. Although there
were over 70 equipment/fuel combinations inventoried, the 30 most significant
combinations account for over 90 percent of NOX emissions. The ranking
of a specific equipment/fuel type depends both on total installed capacity
and emission factors. A high ranking, therefore, does not necessarily
imply that a given source is a high emitter; large installed capacity
may offset a low emission factor to give the high ranking. In general,
58
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Industrial Process Combustion 3.65%
Noncombustlon l.P/5
Warm Air Furnaces 2.7%
Gas Turbines 3.7£%
Fugitive 4.4*
Incineration 0.3%
Reciprocating
1C Engines
15.9%
1974 Stationary Combustion Source NOX Emissions
Utility Boilers
Packaged Boilers
Warm Air Furnaces
Gas Turbines
Reciprocating 1C Engines
Industrial Process Combustion
Noncombustion
Incineration
Fugitive
TOTAL
1.000 Hq
5,566
2,345
321
440
1,857
425
193
40
498
11,685
1 .000 Tons
6,122
2,383
353
484
2.040
470
212
44
548
12,861
Percent
Total
47.6
20.1
2.7
3.76
15.9
3.65
1.6
0.3
4.4
100
Figure 7-1. Distribution of stationary anthropogenic NOX emissions
for the year 1974 (stationary fuel combustion:
controlled NOX levels).
59
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TABLE 7-1. 1974 SUMMARY OF AIR AND SOLID POLLUTANT EMISSION FROM STATIONARY
FUEL BURNING EQUIPMENT (1,000 Mg)
en
O
Utility Boilers
Packaged Boilers
Ham Air Furnaces
& Misc. Comb.
Gas Turbines
Reclp. 1C Engines
Process Heating
TOTAL
N0xb
5,566
2,345
321
440
1,857
425.8
10,954
SOX
16,768
6,405
232
10.5
19.6
1005
24,440
HC
29.5
72.1
29.7
13.7
578
166
889
CO
270
175
132.6
73.4
1.824
10,039
12,511
Part Sulfates POM AshDRemoval
5,965 231 0.01 - 1.2 6.18
4,930 146 0.2-67.8 4.41
39.3 6.4 0.06
17.3 a *
21.5 " *
6,216.7 ' *
17,190 382 69
Sluiced
Ash Removal
24.78
1.07
~
~
~
*No emission factor available
bControlled HOX
Based on 80 percent hopper and flyash removal by sluicing methods; 20 percent dry solid removal
-------
TABLE 7-2. NOX MASS EMISSION RANKING OF STATIONARY COMBUSTION EQUIPMENT AND CRITERIA POLLUTANT
AND FUEL USE CROSS RANKING
Sector
1 Utility Boilers
2 Reciprocating 1C
Engines
3 Utility Boilers
4 Utility Boilers
5 Utility Boilers
6 Utility Boilers
7 Utility Boilers
8 Reciprocating 1C
Engines
9 Packaged Boilers
10 Packaged Boilers
11 Utility Boilers
12 Packaged Boilers
13 Utility Boilers
14 Packaged Boilers
IS Packaged Boilers
16 Utility Boilers
17 Packaged Boilers
18 Industrial
Process Comb.
19 Utility Boilers
20 Packaged Boilers
Equipment Type
Tangential
>75 kW/cyl
Wall Firing
Cyclone Furnace
Wall Firing
Wall Firing
Horizontally Opposed
75 kW to 75 kW/cyl
Hatertube >29 MW
Water-tube Stoker <29 MW
Horizontally Opposed
Watertube >29 MW
Tangential
F1 re tube Scotch
Watertube <29 MW
Horizontally Opposed
Watertube <29 MW
Forced ft Natural Draft
Refinery Heaters
Tangential
F1 re tube Firebox
Fuel
Coal
Gas
Coal
Coal
Gas
011
Gas
011
Gas
Coal
Coal
011
Oil
Oil
Gas
011
Coal
011
Gas
011
Annual NOX
Emission^
(Mg)
1,410,000
1.262,000
946,000
863,500
738,300
481 ,000
378,700
325,000
318,500
278,170
270,800
232.480
208,000
203,990
180,000
177,900
164.220
147.350
146,000
139.260
Cumulative
(Mg)
1,410,000
2.672,000
3.618,000
4,481.500
5.219.800
5.700,800
6,079,500
6,404.500
6,723,000
7,001,170
7,271,970
7,504,450
7,712,450
7,916,440
8,096,440
8,274,340
8,438,560
8,585.910
8,731,910
8.871,170
Cumulative
(Percent)
13.1
24.8
33.5
41.5
48.4
52.8
56.3
59.4
62.3
64.9
67.4
69.5
71.5
73.4
75.0
76.7
78.2
79.6
80.9
82.2
Fuel
Rank
1
21
3
6
4
8
14
>30
16
7
23
26
12
11
5
>30
>30
>30
13
17
SOX
Rank
1
>30
2
3
>30
9
>30
>30
>30
4
5
16
10
11
>30
17
8
29
>30
13
CO
Rank
7
4
6
12
13
17
24
3
29
11
>30
>30
27
>30
>30
>30
>30
>30
>30
>30
HC
Rank
16
1
23
9
28
27
>30
3
19
4
>30
26
>30
>30
22
>30
>30
18
>30
>30
Part
Rank
2
>30
5
13
>30
18
>30
26
>30
1
7
I
22
19
16
>30
27
9
21
>30
20
-------
TABLE 7-2. Concluded
Sector
21 Packaged Boilers
22 Gas Turbines
23 Packaged Boilers
24 Mara Air Furnaces
25 Packaged Boilers
26 Packaged Boilers
27 Gas Turbines
28 Reciprocating 1C
Engines
29 Industrial
Process Comb.
30 Utility Boilers
Equipment Type
Water-tube Stoker
4 to 15 MM
Watertube <29 MM
Central
Flretube Stoker <29 MM
Firetube Scotch
>15 MM
>75 W/cyl
Forced & Natural Draft
Refinery Heaters
Vertical and Stoker
Fuel
Coal
Oil
Oil
Gas
Coal
Gas
011
Oil
Gas
Coal
Annual NOX
Emissions
(Kg)
125.350
118,500
116.430
106.300
102.040
98,010
97,400
94,000
92,608
90,900
Cumulative
(Hg)
8.996.520
9,115,020
9,231 ,450
9,337,750
9,439,790
9,537,800
9,635,200
9,729,200
9,821 ,808
9,912,708
Cumulative
(Percent)
83.4
84.5
85.6
86.5
87.5
88.4
89.3
90.2
91.0
91.9
Fuel
Rank
>30
30
27
2
29
19
>30
>30
15
>30
Rank
7
>30
15
>30
6
>30
>30
>30
>30
12
CO
Rank
28
15
>30
10
>30
>30
>30
22
>30
>20
HC
Rank
29
14
>30
8
10
>30
30
13
7
>30
Part
Rank
8
>30
23
25
6
>30
>30
>30
30
>10
ro
-------
coal-fired sources rank high in SOX and participate emissions, while 1C
engines rank high in emissions of CO and hydrocarbons.
This emissions inventory assessment effort will culminate in a special
report which will:
Characterize stationary source equipment and fuel use
t Identify and categorize stationary source air pollutants and liquid
and solid wastes
t Assess and standardize available emissions data
Present a detailed emissions inventory with emission projections
0 Identify the pollution impact potential of sources and rank sources
to reflect control development needs.
As part of this report, regional inventories are being developed
from the national inventory. In addition, the national inventory is being
projected to 1985 and 2000 for several energy and equipment growth scenarios.
A source assessment which considers population exposure, health effects,
and source growth (described in Section 4.2) will be performed. This
assessment will culminate in ranking stationary uncontrolled combustion
sources on the basis of potential multimedia impacts.
During the remainder of the NOX E/A program, NOX E/A testing and
the results from other related assessment programs will be closely monitored
to ensure that the NOX E/A final report reflects the most accurate and
representative data available. Updates of the special report will be
provided during the remainder of the NOX E/A to disseminate the best current
data to the EPA and research community.
7.2 INCREMENTAL EMISSIONS DUE TO NOX CONTROLS
This section summarizes the preliminary evaluation of the demonstrated
and potential effects of combustion modification NOX controls on incremental
emissions.* The results will help to guide priorities for subsequent NOX E/A
efforts in compiling incremental emission data, characterizing impacts, and
studying control processes. In the preliminary evaluation, attention was
focused on flue gas emissions from major sources operating at steady-state
conditions and using near-term NOX controls. These situations were
considered the most important to the program, and were the only ones for
which significant data existed. Subsequent effort will consider liquid solid
effluents, minor sources, and alternate or advanced NOX controls.
incremental emissions are the changes in emission levels of combustion-
generated pollutants other than NOX, which can be ascribed to using a NOX
control.
63
-------
It is important to note that efforts to date have been concerned only
with estimating incremental emission rates, with little regard to potential
impact. Ultimately, the significance of the incremental emissions will
depend on baseline, uncontrolled pollutant emission rates, maximum
acceptable ambient pollutant concentrations, and other factors such as
pollutant transport and transformation. The preliminary screening of
potential incremental impacts due to NOX controls, considering these factors,
is summarized in Section 8.
The preliminary evaluation was performed in three steps. In the first
step, preliminary screening, changes in the levels of incremental emissions
were qualitatively linked to the combustion conditions resulting from using
specific NOX controls, based on knowledge of pollutant formation mechanisms.
Of course, this preliminary screening represented only informed speculation
based on what was known about how combustion NOX controls act, and how
combustion-generated pollutants are formed. But it was used only to screen
the matrix of control/pollutant pairs for expected adverse emission effects,
and thereby guide priority setting for future study in the absence of
supporting data.
The second step sought to substantiate the postulates formed in the
preliminary screening by compiling and evaluating data from field tests in
which incremental emission data were collected. Data were very limited, and
insufficiencies were noted.
The third step followed from the first two and grouped control
technique/pollutant pairs into the following three groups according to their
potential for increased emissions:
0 High potential emissions impact, where the emissions data unambiguously
show that applying the NOX control results in significantly increased
emissions of a specific pollutant
0 Intermediate potential emission impact, where preliminary screening
of formative mechanisms indicates that NOX control could conceivably
cause increased pollutant emissions, but confirming data are lacking,
contradictory, or inconclusive
0 Low potential emission impact, where the emissions data clearly
show that specific pollutant emission levels decrease or are unaffected
when the NOx control is applied, or where the preliminary screening
definitely indicates a similar conclusion, even though data are
1ack i ng
Tables 7-3 through 7-5 show these groupings for boilers, 1C engines, and
gas turbines, respectively.
As Table 7-3 illustrates, using preferred NOX combustion controls
on boilers should have few adverse effects on incremental emissions of
CO, vapor phase hydrocarbons, or particulates. Although indiscriminately
lowering excess air can drastically affect boiler CO emissions, and particulate
emissions can increase with off-stoichiometric combustion and flue gas
64
-------
TABLE 7-3. EVALUATION OF INCREMENTAL EMISSIONS DUE TO NOX CONTROLS APPLIED
TO BOILERS
NOV Control
X
Low Excess Air
Staged
Combustion
Flue Gas
Re circulation
Reduced Air
Preheat
Reduced Load
Water
Injection
Ammonia
Injection
Incremental Emission
CO
+4-
0
0
0
0
0
0
Vapor Phase
HC
0
0
0
0
0
0
0
Sul fate
+
+
+
+
+
+
++
Parti cul ate
0
+
+
0
0
+
+
Organ ics
++
++
+
+
+
+
0
Segregating
Trace Metals
+
+
+
0
0
0
+
Nonsegregating
Trace Metals
0
0
+
+
0
0
0
U1
Key: ++ denotes having high potential emissions impact
+ denotes having intermediate potential emissions impact, data needed
0 denotes having low potential emissions impact
-------
TABLE 7-4. EVALUATION OF INCREMENTAL EMISSIONS DUE TO NOX CONTROLS APPLIED
TO 1C ENGINES
NO Control
A
Retard
Ignition
Increase A/F
Ratio
Decrease A/F
Ratio
Exhaust Gas
Recirculatlon
Decrease
Manifold Air
Temperature
Stratified
Charge
Cylinder
Design
Derate
Increase Speed
Water Injection
Incremental Emission
CO
H-
0
H-
f
0
+
H-
+
+
Vapor Phase
HC
+
++
H-
+
H-
f
H-
+
H-
Sul fate
0
M-
0
0
+
0
+
0
0
Partlculate
H-
0
f
++
0
+
0
+
+
Organlcs
f
0
+
+
0
+
0
+
+
Segregating
Trace Metals
0
0
+
+
+
+
+
+
+
Nonsegregating
Trace Metals
0
0
0
0
0
0
0
0
0
(ft
CTl
Key: ++ denotes having high potential emissions impact
+ denotes having intermediate potential emission impact, data needed
0 denotes having low potential emissions impact
-------
TABLE 7-5. EVALUATION OF INCREMENTAL EMISSIONS DUE TO NOX CONTROLS APPLIED
TO GAS TURBINES
NO Control
J\
Water or Steam
Injection
Lean Primary
Zone
Early Quench
with Secondary
Air
Increase Mass
Flowrate
Exhaust Gas
Redrculation
A1r Blast/ A1r
Assist
Atomization
Reduced Air
Preheat
Reduced Load
Incremental Emission
CO
4-4-
0
0
f
+
0
0
H-
Vapor Phase
HC
4-
0
0
4-
4-
4-
0
H-
Sul fate
0
4-
0
0
0
0
+
4-
Parti cul ate
4-
0
4-
4-
4-
+
0
H-
Organ ics
+
0
+
+
+
f
0
+
Segregating
Trace Metals
f
+
4-
4-
4-
4-
4-
4-
Nonsegregating
Trace Metals
0
0
0
0
0
0
0
0
en
Key: ++ denotes having high potential emissions Impact
4- denotes having Intermediate potential emissions Impact, data needed
0 denotes having low potential emissions impact
-------
recirculation, with suitable engineering during development and careful
implementation, these incremental emissions problems can be minimized.
In contrast, applying almost every combustion control has intermediate
to high potential impact on incremental emissions of sulfate, organics, and
trace metals. For trace metal and organic emissions, substantiating data
were largely lacking, but fundamental formation mechanisms caused justifiable
concern. In the sulfate case, fundamental formation mechanisms suggested
that these emissions would remain unchanged or decreased with all controls
except ammonia injection. However, complex interactive effects were
difficult to clarify, and this pollutant class was considered sufficiently
hazardous to justify some concern in the absence of conclusive data.
Table 7-4 shows that the incremental emissions of all pollutant
classes except nonsegregating trace metals potentially increase when NOX
controls are used on 1C engines. Increased emissions of CO, vapor phase
hydrocarbons (HC), and particulate (smoke) are of primary concern, while
sulfates, organics, and segregating trace metals from engines burning high
sulfur diesel fuels are of less concern.
Similarly, certain NOX controls applied to gas turbines can be
expected, in selected instances, to adversely affect all incremental
emissions except nonsegregating trace metals, as shown in Table 7-5. Again,
increased sulfate, particulate, organic, and segregating trace metals are of
some concern in sources firing high sulfur diesel fuels. If residual oil
firing in gas turbines increases, these concerns would become more serious.
Presently this appears unlikely, due to materials problems such as
sulfidation.
The incremental emission evaluations presented in Tables 7-3 through
7-5 are not intended to signify potential for adverse environmental impact.
Rather, the evaluations list source/control/pollutant combinations for which
emissions may increase when NOX controls are used. Evaluating potential
adverse environmental impacts would require comparing source-generated,
ambient pollutant concentrations with upper limit threshold concentrations of
the pollutants based on health or ecological effects (as described in Section
3). These comparisons will be made in future program efforts. However, some
conclusions based on the results to date are presented below.
In general, the data on incremental multimedia emissions due to NOX
controls were very sparse. Although more data were available for flue gas
emissions than for liquid or solid effluent streams, the only data which
allowed quantitative conclusions were for emissions of criteria pollutants
from major sources employing commonly-applied controls. Data on sulfates,
trace metals, and organics (POM) were few, experimentally uncertain, and
highly dependent on fuel properties, while incremental emissions in liquid
and solid effluents and during transient or nonstandard operation were almost
nonexistent. Therefore, these data have generally been excluded in the
present evaluation. Test data from ongoing related programs and from the NOX
E/A test programs will be needed before incremental emissions impacts can be
evaluated for other than flue gas emissions during standard operation.
68
-------
Emissions of CO, HC, particulate (smoke), and $03 (with or without
NOX controls) have been limited in the past for operational reasons rather
than environmental impact. CO, HC and smoke emissions reduce efficiency and
may present safety hazards. High 303 production can lead to acid condensation,
corrosion and in many cases, to acid smut formation. All of these emissions
are quite sensitive to combustion process modifications for NOX control.
Except for $63, incremental emissions of these pollutants normally tend to
increase when NOX controls, particularly low excess air and off-stochiometric
combustion, are applied. Development experience has shown, however, that with
proper engineering these emissions can be limited under low-NOx conditions.
Therefore, it should be emphasized that incremental emissions of criteria
pollutants can be viewed more as a constraining criterion to be addressed
during control development rather than as an immutable consequence of low-
NOx firing.
Moreover, the limit on emissions for satisfactory operation is
generally more stringent than the limit for acceptable environmental impact.
Of course, the environmental constraints will be carried through future
impact assessments in the NOX E/A for all potentially significant pollutants,
but in many cases, they will need to be supplemented by operational
constrai nts.
The situation for other flue gas pollutants is more uncertain.
Conventional combustion process modifications -- low excess air, off-
stoichiometric combustion, flue gas recirculation -- may increase emissions
of sulfates, organics, and segregating trace metals from sources firing
coal or residual oil. However, this conclusion has been based on sparse
data or, lacking that, on fundamental speculation. Clearly more data
will be needed. In contrast to CO, HC, and smoke, little is known on
whether these emissions can be constrained to acceptable levels during
control development.
In light of the relative scarcity of data on combustion modification
effects on incremental emissions, future program test efforts, described
in Section 7.3, will stress measuring these emissions. Specifically,
emphasis will be placed on assessing the effects of NOX combustion controls
on flue gas emissions of 503, condensed sulfate, trace metals, organics, and
trace species such as NHi and HCN, as well as emitted particle size
distribution and particulate composition as a function of size. In addition,
solid and liquid effluents will be collected and analyzed where appropriate.
Of course, all other ongoing field test programs collecting similar data will
be closejly monitored.
7.3 TEST PROGRAM DEVELOPMENT
During the compilation of the baseline emission inventory and
the evaluation of incremental emissions due to NOX controls, it became
apparent that data were lacking in several key areas. Most noteworthy
was the virtual absence of data on the effects of NOX combustion controls
on emission levels of noncriteria flue gas pollutants and liquid and solid
effluents. In response to these identified data needs, as well as additional
69
-------
requirements which may develop in future program efforts, NOX E/A field test
programs will be initiated.
Whenever possible, field testing will be performed as subcontracted
additions to planned or ongoing tests since this is most cost-effective.
However, where program needs cannot be satisfied through add-on testing, new
test series will be initiated.
Efforts to date have focused on identifying specific test data needs
and test add-on opportunities for characterizing utility boilers. As
discussed in Section 8, the utility boiler category was ranked as having the
highest environmental impact potential. Therefore, it is being treated first
in the process engineering and environmental assessment studies.
Results of the first year preliminary environmental assessment and
subsequent process engineering activities have identified specific data needs
associated with utility boiler design types and fuel combinations. NOX
modifications to coal-fired boilers have been extensively tested in past
programs, so NOX emission levels from these boilers have been relatively well
characterized. Tangential and front wall firing configurations have been
especially well characterized. However, data on emissions other than
criteria pollutants, and incremental emissions data due to NOX controls are
very sparse.
Baseline and controlled NOX emissions from oil-fired boilers have also
been reasonably well characterized, although more data are needed for an in-
depth treatment. Front wall-firing configurations have been the most
extensively tested. Again, noncriteria pollutant data, particulate data, and
incremental emissions data are very limited.
Emission data for gas-fired boilers, even though somewhat limited, are
sufficient for characterizing NOX emissions. Although incremental emission
data are essentially nonexistent from these sources, the need for these data
is less critical. Process engineering treatments of gas-fired utility
boilers will be less comprehensive because the use of gas for generating
power is rapidly declining. Natural gas will probably be totally unavailable
for generating power by 1985.
Based on the above, utility boiler test priorities will focus on
coal- and residual oil-fired equipment, particularly tangential and
horizontally-opposed firing configurations. Test matrices at each chosen
site will address the data needs identified in Sections 7.1 and 7.2.
Emphasis will be given to obtaining both baseline and incremental data as a
function of combustion control parameters on emissions of flue gas NOX, CO,
HC, SO?, $03, trace metals, organics, particulate, and particle size
distribution. In addition, obtaining data on particulate composition as a
function of size, specifically trace metal, condensed sulfate, and condensed
organic levels, will be stressed.
In general, utility boiler testing will follow the sample test
matrices illustrated in Tables 7-6 and 7-7 for vapor phase and condensed
phase constituents, respectively. The "X's" in the tables represent analyses
to be performed under each test condition. Level 1 sampling and analysis
70
-------
TABLE 7-6. SAMPLE TEST MATRIX VAPOR PHASE CONSTITUENTS
Pollutant
species
NOX
C02
CO
S02
02
S03
Trace
Metals
Organics
>C6
Partlcu-
late
Sampling and
Method
Continuous monitor,
chemi luminescent
Continuous monitor,
NDIR
Continuous monitor,
NOIR
Continuous monitor,
UV fluorescence
Continuous monitor,
NDIR
Method 8 probe/
train
SASS train
SASS train
Method 5
probe/train
analysis Test Points8
Baseline Baseline 1CK FGR Max FGR 1/2 max OSC Max OSC Max OSC
Comments high ex- m1n ex- min EA Min EA Mln EA Min EA Max FGR
cess air cess air
Two-dimensional X X X X XXX
sampling rake
giving composite
sample. Sample
upstream of
air heater.
See above X X X X XX
See above X X X X XX
See above X X X X XX
See above, also X X X X XX
sample up and down-
stream of parti cu-
late collection
device to calculate
air In-leakage.
X X X X XX
X X
Solvent extraction of X x
absorbent elutrate to
8 fractions
Sample up and down- X X X X XX
stream of partlculate
collection device.
-------
TABLE 7-6. Concluded
Pollutant
species
Particle
size
distribu-
tion
Trace
species
HCN, HC*,
NH3, COS,
H?S, and
HC<6
Sampling
Method
Method 5
probe/ train
with cyclones,
or Impactors
Gas grab
sample
and analysis Test Points3
Baseline Baseline 10X FOR Max FGR 1/2 max OSC Max OSC Max OSC +
Comments high ex- m1n ex- m1n EA M1n EA Mln EA M1n EA Max FGR
cess air cess air
Particle size frac- X X X X XX
tlonatlon to at least
four fractions.
Gas chromatograph with X X
flame 1on1zat1on
detector for analysis
ro
T-4/Z
aAll test points at the same boiler load. Boiler load within 20X of rated capacity.
-------
TABLE 7-7. SAMPLE TEST MATRIX - CONDENSED PHASE CONSTITUENTS
Pollutant
species
Flue gas
Trace
elements
Sulfate
NH4 HS04
Organics
>CG
Sampling
Method
parti cu late
Spark source mass
spectroscopy or
atomic absorption
Met chemical
analysis
Met chemical
analysis
Met chemical
analysis or GC-
mass spec.
Hopper ash and bottom ash
Trace
elements
Sulfate
NH4 HS04
Organics
>CG
Assay as above
and analysis
Comments
Assay each
parti oil ate size
fraction, both up
and downstream of
particle collection
device catches.
Assay for at least
20 elements.
See above
See above
Assay lumped particu-
late catch
Assay hopper and
bottom ash
separate ly
See above
Test Points8
Baseline Baseline 10X FGR Max FGR 1/2 max OSC Max OSC Max OSC
high ex- min ex- m1n EA Min EA Min EA Min EA Max EA
cess air cess air
X X X X XXX
X X X X XX
X X X X XX
X X
X X
X X
X X
X X
GO
aAll test points at the same boiler load. Boiler load within 20JC of rated capacity.
T-473
-------
procedures (Reference 28) will be used wherever appropriate. The NOX
controls identified for major study emphasis (see Section 8) will be applied
incrementally. New burner design testing, although not specifically shown in
Tables 7-6 and 7-7, will also be performed. Because of their expense,
certain analyses (notably organic assays) will be performed only under
baseline and maximum controlled (low-NOx) conditions to supply key data
most cost-effectively. It is important to note that Tables 7-6 and 7-7
represent a general test plan that is not strictly applicable to a specific
boiler/fuel combination. Thus, flue gas recirculation will not be tested on
coal-fired boilers, and hopper and bottom ash sampling do not apply to oil-
fired boiler testing.
In addition to the analyses noted in Tables 7-6 and 7-7, ultimate
fuel analyses of samples taken before, during, and after testing will
be performed. The same fuel will be fired throughout each boiler test
series. The need for bioassay analyses, and the procedure to be followed
when these analyses are performed, will be coordinated with the IERL working
group advising environmental assessment activities.
Current plans are to conduct a series of 19 field tests using
add-ons to existing programs whenever possible. The 19 tests, with
an appropriate test priority reflecting the source ranking discussed in
Section 8, are summarized below. Actual test scheduling may not fully
reflect the priority ranking, however. The timing of test opportunities
and the need to meet special report schedules may dictate the order in
which tests proceed.
Priority
1-4
5-7
8-9
10
11-12
13
14
15
16
Test
Coal-fired utility boiler. Includes one test
each of tangential, wall-fired, and horizontally-
opposed fired boiler if possible.
Oil-fired utility boiler. Includes one test
each of tangential, wall-fired, and horizontally-
opposed fired boiler, if possible. At least
one boiler should incorporate combined F6R
and OSC control.
Coal-fired watertube industrial boiler. At
least one spreader stoker.
Oil-fired gas turbine with wet controls
Advanced burner or firebox design
Oil-fired firetube industrial boiler
Oil-fired watertube industrial boiler
Oil-fired warm air furnace
Spark ignition 1C engine
74
-------
17 Compression ignition 1C engine
18-19 Industrial process furnace, at lease one firing
process gas
75
-------
SECTION 8
ENVIRONMENTAL ALTERNATIVES ANALYSIS
During the first year effort, an environmental alternatives analysis
was used to set priorities for the process studies, environmental assess-
ments, and testing programs. These priorities relate directly to the program
needs:
Assess current and impending combustion modification applications
to quantify environmental, economic, and operational impacts
Assess emerging, advanced technology to guide control development
Identify potential adverse impacts which should be addressed
in the control development program
-- Estimate which controls will be needed and are most effective
to attain air quality goals to the year 2000
To address these needs, the program gives primary early emphasis to
assessing current and impending control applications. Assessment of advanced
technology applications will proceed at a lower level of effort in near-term
activities, but will be emphasized toward the end of the program. During the
program, separate process engineering/environmental assessment reports will
be generated for each major equipment category. These reports will focus
mainly on current technology since these applications are most timely from
an environmental standpoint, and are the most extensively tested. The final
report will document the assessment of far-term applications and will update
the earlier assessment of near-term applications.
To support this approach, preliminary priorities are needed for:
t The sequence in which the major source categories are to be
assessed and the level of effort devoted to each
The near-term source/control applications to be assessed
0 The source/control combinations to be addressed in the assessment
of far-term applications
The effluent stream/pollutant combinations to be emphasized in the
test programs and assessments
77
-------
In program work to date, preliminary source/control screening was con-
ducted independently of pollutant screening. The source/control combinations
were initially screened on the basis of significant near-term or far-term
application. Pollutants for the resultant source/control combinations were
then screened for potential adverse impacts, and the results were then com-
bined to set program priorities.
Earlier sections of this report summarized most of the information
required to determine these four priorities. This section consolidates that
information and also estimates near- and far-term source/control requirements
to attain and maintain air quality. Priorities were then set in the sequence
of the preceding list. The qualitative priorities set will be updated and
reevaluated as new data become avaiable.
8.1 EVALUATION OF NQX CONTROL REQUIREMENTS
The source/control priorities within the NOX E/A largely depend on the
extent to which specific sources and controls will need to be used in this
century to meet N0£ air quality standards. To help set these priorities, the
systems analysis model described in Section 4.4 was developed to relate
ambient air quality to several scenarios on source growth, control
implementation, and regulatory policy. For preliminary calculations we have
used the source-weighted rollback model for the air quality model in the Los
Angeles Air Quality Control Region (mobile dominated) and the Chicago AQCR
(stationary dominated). Emission inventories were, with some modifications,
taken from the NEDS file. Two scenarios each for mobile and stationary source
growth were considered. In addition, the sensitivity of the results was in-
vestigated by considering two base-year annual average, ambient N02 concen-
trations for calibration of the model, and several different source weight-
ings for powerplants and mobile sources.
The results of the preliminary screening analysis for the NOX control
needs of the Los Angeles AQCR are shown in Table 8-1. This table outlines
control requirements for Los Angeles for 1985 (upper entry) and 2000 (lower
entry), as a function of base year N02 concentration, powerpi ant and mobile
source weighting factor, and source growth scenario. For calculations
summarized in the table, the nominal growth case* assumes moderate growth for
stationary sources (influenced by conservation, emissions off-set policies
and rising energy costs), a 3 percent per year growth in vehicle population,
and 0.62 g N02/km (1 g/mile) mobile source emission standard beyond 1980.
The low mobile case has the same stationary source scenario but assumes 1
percent per year growth in vehicle population and an emission factor of
0.25 g N02/km (0.4 g/mile) beyond 1981. The high stationary source case is
an extension of historical trends in stationary source growth and has the
same mobile growth as the nominal growth case.
*The growth rates for each source category are given in detail in Section 7
of Reference 16.
78
-------
TABLE 8-1. SUMMARY OF CONTROL LEVELS REQUIRED TO MEET NO? STANDARD
IN LOS ANGELES, AQCR 024
Case
BYR = 132 ug/m3
PP = 1.0
MS = 1.0
PPa = 0.7
MS = 1.2
BYR = 160 yg/m3
PP = 1.0
MS = 1.0
PPa = 0.7
MS = 1.2
Nominal Growth
0
Low Mobile
0
0
0
0
0
0
High Stationary
aThe low emission layer in Los Angeles prevents wide dispersion
of the emissions from elevated sources; therefore, the powerplants
are down weighted to 0.7. Also, the highest ambient levels occur
in regions of high mobile emissions. Thus the mobile sources are
weighted upwards.
0 No additional control required
1 Controls from Group I
2 Controls from Groups I and II
3 Controls from Groups I, II, and II
4 Violation of NAAQS, insufficient control to meet ambient
standard
1985
2000
PP Powerplants Weighting Factor
MS Mobile Sources Weighting Factory
BYR Base Year Calibration
79
-------
In addition two values for base year ambient N02 concentrations were
used: 132 yg/nr and 160 yg/nr. These values represent the lower and upper
limits of reported maximum annual averages from various monitoring stations
and for several different four-quarter averaging periods. The source-
weighting factors for powerplants (PP) and mobile sources (MS) were varied
to show the sensitivity of the results to assumptions on dispersion of NOX
from tall stacks relative to ground level sources.
The control groups cited in Table 8-1 refer to the ranking shown on
Table 8-2. Here the control techniques are ranked on the basis of cost
effectiveness in improving air quality. The negative costs indicate a net
cost savings due to improvements in fuel consumption efficiency. The most
obvious conclusion from Table 8-1 is that the required control level is
dominated by the assumptions on the mobile source emissions. This is not
really surprising since mobile sources accounted for 66 percent of the NOX
emissions in 1973. In the low mobile case the combination of low growth (1
percent per year) and stringent controls (0.25 g/km in 1981) results in a 63
percent reduction in mobile emissions in 1985 and a 66 percent reduction in
2000. This more than offsets the growth in stationary sources and results in
a net reduction in total emissions of 36 percent and 38 percent,
respectively. This level of reduction is enough to achieve the ambient
standard except in the high (160 yg/m3) base year cases. Even in the nominal
mobile case, a slight increase in the weighting of the mobile sources has
significant impact in 1985.
In contrast to the low mobile cases, maximum control is needed for all
other cases in 2000, and also for the high base year ambient concentration
case in the near term (1985). Again, both of these are consequences of the
dominance of the mobile sources. Control of the stationary sources cannot
yield sufficient emission reduction to offset growth and the large mobile
source emissions contribution.
Analogous results for Chicago are shown in Table 8-3, with the
corresponding control ranking given in Table 8-4. The tables indicate that
control of stationary sources is required in all cases, except in 1985 for a
base year (1973) concentration of 96 yg/m3. The principal reason for this
(no control in 1985) is that the reduction in mobile source emissions
counterbalances the growth in stationary sources. For example, in the
nominal growth case, mobile source emissions in 1985 are 123 Gg below their
1973 level, whereas stationary sources have increased by only 112 Gg. In the
high stationary growth case, however, an increase of 154 Gg for stationary
sources in 1985 is enough to require a small amount of control. Even with
the low base year concentration, the complete range of combustion
modification controls is needed in the year 2000. For the high base year
concentration cases, combustion modifications and ammonia injection are not
always sufficient, and, even in the low mobile case, combustion modification
controls are needed. (The 1973 mobile NOX emissions constitute 45 percent of
the total in Chicago; consequently, mobile emissions are not as dominant as
in Los Angeles.)
The conclusions for the Chicago AQCR are essentially the same as for
Los Angeles. For the long term, combustion modifications will be required
and in some cases, will not be sufficient to meet the annual standard. In
80
-------
TABLE 8-2. CONTROL PRIORITIZATION FOR LOS ANGELES
(2000, equal source weighting)
Rank
f 1
I <
II <
2
3
4
5
6
7
>. 8
' 9
10
11
12
13
14
15
16
17
18
19
20
I 21
r22
in J "
i 24
L 25
Source/Control
RES. FURN NEW BURNER
SM COHH FURN NEW D.
IND (WTB) LEA
SM COMM FURN A.D. 11
COMM/INST FURN A.D. 12
RES. FURN A.D. 11
RES. FURN A.D. 12
IND (FTB) LEA
SM PP LEA+OSC
1C ENGINES ADO A/F
«HED PP TO 250 PPM
1C ENG.-NEW ADJ A/F
1C ENG.-NEW A.D.
"LA PP TO 250 PPM
SM PP LEA+OSC+FGR
1C ENGINE-EGR
aCCGT-NEW-H20 INJ
CCGT-NEW A.D. 11
CCGT-NEW A.D. 12
IND (WTB) LEA+OSC
IND (FTB) LEA+FGR
LA PP C.M.+NH3 INJ
MED PP C.M.+NH3 INJ
SM PP C.M.+NH3 INJ
IND (UTB) C.M.+NH3
Cost Per Unit
Change in Air Quality
10'$/(ug/niJ)
-15.4
-14.6
-13.9
-12.7
-13.3
-11.4
-11.3
- 3.67
1.57
2.18
2.43
2.48
0.305
2.50
2.74
4.10
4.13
3.38
3.94
5.00
6.57
6.74
7.59
8.25
13.4
X Reduction
per Unit
40
40
7
60
80
60
80
17
45
30
16
11
51
16
58
20
30
50
75
17
40
79
79
79
42
'Required to meet present legislated emission levels.
A.D. - Advanced design
C.M. - Combustion modifications (LEA, OSC, F6R)
COMM - Commercial
CCGT - Combined cycle gas turbine
EGR - Exhaust gas recirculation
FGR - Flue gas recirculation
FTB -Flretube boiler
FURN - Furnace
H20 INJ - Water Injection
I, IND - Industrial
INST - Institutional
LA - Large
LEA - Low excess air
MED - Medium
OSC - Off-stolchlmetric combustion
PP - Power plant
RES - Residential
SM-Small
UTB - Uatertube boiler
81
-------
TABLE 8-3. SUMMARY OF CONTROL LEVELS REQURIED TO MEET NO? STANDARD
IN CHICAGO, AQCR 067
Case
BYR = 06 ug/m3
PP = 1.0
MS = 1.0
PP = 0.5
MS = 1.2
PP = 0.2
MS = 1.0
BYR = 120 ug/m3
PP = 1.0
MS = 1.0
PP = 0.5
MS = 1.2
PP = 0.2
MS = 1.0
Nominal Growth
0
Low Mobile
0
0
High Stationary
0
control of stationary sources is required in this case than in the
PP = 1.0 case because the effectiveness of the powerplant controls in
reducing ambient air quality is significantly reduced by the low source
weighting factor.
0 No additional control required
1 -- Controls from Group 1
2 Controls from Groups I and II
3 -- Controls from Groups I, II, and III
V -- Violation of NAAQS, insufficient controls to meet ambient standard
1985
2000
PP Powerplant Weighting Factor
MS Mobile Sources Weighting Factor
BYR Base Year Calibration
82
-------
TABLE 8-4. CONTROL PRIORITIZATION FOR CHICAGO
(2000, equal source weighting)
Rank
1
2
3
4
5
6
I 7
8
9
10
11
12
13
14
15
16
17
18
19
20
II 21
22
23
24
25
26
27
28
/ 29
30
31
III 32
33
34
* 35
:36
Source/Control
RES. NEW BURNER
RES. FURN A.D.fl
RES. FURN A.D.I2
SM COMM FURN NEW D
SM COMM FURN A.D.fl
SM COMM FURN A.D.I2
IWTB-OIL LEA
N IWTB-C LEA
N IWTB-0 LEA
IWTB-COAL LEA
PP-OIL LEA
N IFTB-0 LEA
IFTB-OIL LEA
PP-COAL LEA
N PP-C LEA+OSC 1982
N PP-C A.D.fZ 1987
PP-COAL LEA+OSC
N IFTB-0 LEA+FGR
N IWTB-0 LEA+OSC
N IWTB-0 A.D
-------
the short term, combustion modifications are needed unless the low base year
concentration is valid.
These results strongly suggest that all possible stationary source
control methods may need to be developed. According to the results discussed
above, a less vigorous approach could be justified only if all of the most
favorable assumptions were valid (i.e., low base year concentration, low
mobile growth, strict and effective mobile control, and validity of the
higher mobile weighting assumption). It is unreasonable to expect that all
of this will happen, and it is therefore imprudent to plan control
development on such an assumption. For the short term, the current combustion
modification control technology might be sufficient if a favorable mobile
situation exists. For the longer term, however, all the advanced control
methods presently considered whould be pursued, including ammonia injection.
Research on even more effective methods seems justified.
These conclusions can be qualitatively extended to many of the regions
identified as priority AQCRs and AQMAs. Those that are mobile dominated will
respond to stationary source control in much the same manner as Los Angeles.
It is quite likely that for these AQCRs, mobile source controls (0.62 g/km)
would be sufficient for the short term; however, combustion modifications on
stationary sources would be required in the long term. The stationary source
dominated AQCRs, particularly those in the upper half of Table 4-2, will
likely require combustion modifications,and perhaps ammonia injection, in
both the near term and far term. It should be emphasized that the present
analysis focuses on control requirements to attain alternate potential
standards, e.g., a short-term N02 standard, will be evaluated later in the
NOX E/A program. The results of this evaluation could show additional
control requirements over those identified here.
The conclusions for the required control levels for both Los Angeles
and Chicago are very similar to those of other studies, for example, the DOT
study (Reference 2) and an EPA study (Reference 1). Both of these studies
reported that neither Los Angeles nor Chicago could achieve the ambient
standard with even maximum stationary source control and 0.25 g/km mobile
controls. The results here indicate that it may be possible in favorable
circumstances. The primary differences between the present analysis and these
two are in the growth rates and the base year ambient levels for which the
models were calibrated. The DOT study allowed stationary sources to grow
at 3.9 percent per year. The EPA study considered 5 percent per year growth
and a base year concentration in Los Angeles of 182 ug/nr. Because of growth
restrictions in Los Angeles, an effective annual growth of about 1 percent
per year for the aggregate of the stationary sources was used in this work.
In Chicago, electric powerplant growth was much less than 3.9 percent, primarily
because of growth in nuclear capacity. These factors account for the difference
between never meeting the standard and possibly meeting the standard. These
differences also help to illustrate the influence of the basic assumption
(growth rate, base year concentration, and source weighting factors) on the
quantitative results. However, the qualitative conclusions remain the same.
The conclusions of this portion of the preliminary analysis can be
summarized as follows:
84
-------
The order in which controls should be implemented is significantly
influenced by the fuel savings features of the control method and,
of course, the availability of the technology.
t For the short term, combustion modifications for stationary
sources will be needed for most of the priority AQCRs. Both
retrofit and "new design" controls should be developed,
particularly those that also result in an energy savings.
For the long term, all combustion modifications and ammonia
injection will be required. This may be the case even for the
minimum mobile source emissions case (low growth, 0.25 g/km).
It should be emphasized that these results are only tentative since
they are based on a rather crude air quality model and somewhat qualitative
data. Current efforts are incorporating a reactive photochemical model to
include effects of NO^-HC-oxidant reactions, source height and density, and
meteorological conditions. Process data on control effectiveness and cost
are also being updated through assessment of control technology. In
addition, other N02 critical AQCRs (e.g., New York City and St. Louis) will be
assessed to provide a broader base for conclusions.
8.2 SOURCE/CONTROL PRIORITIES
This section combines the results of Section 8.1 with program results
presented in other sections to set NOX E/A program priorities on sources and
source/control combinations. Priority setting was done in two steps. First,
source priorities were set for the major combustion source/fuel combinations.
These were then used to determine the order for doing process engineering and
environmental assessment studies. They were also used to guide the level of
effort to be devoted to studying each major source category and to individual
design types within each category.
Second, control priorities were set for each source/fuel combination.
The resultant source/control priorities were used to determine which
combinations will be given major or minor emphasis in the process studies and
test programs:
The source prioritization used the following sequence:
Subdivide major source categories (utility boilers) into source/
fuel categories (coal-fired utility); further subdivide to major
design types (tangential) likely to be extensively controlled for
NOX, and minor design types (cyclones) not likely to be extensively
controlled due to dwindling use and/or lack of control flexibility.
Assess the extent controls are used or are planned for each source/
fuel category
Rank source/fuel categories on basis of nationwide mass emissions
of NOX
85
-------
Assess the relative baseline environment impact for each source/
fuel category
Identify the relative effectiveness of implementing near-term and
far-term source controls in maintaining air quality in urban areas
Table 8-5 summarizes the results of establishing these priorities. The
results were largely qualitative due to the uncertainty and lack of data in
many areas. The considerations applied in constructing Table 8-5 are
summarized below.
Source Categorization
The division of the source/fuel category into major and minor design
types followed from results presented in Section 2 of this report. "Major"
refers to conventional designs likely to be controlled for NOX in the near
term. These design types are given primary emphasis in the process studies
and are candidates for field testing. The minor design types are either
obsolete or otherwise unlikely to be subject to significant NOX control in
the near term. Correspondingly, minor design types are given secondary
emphasis in the process studies and are generally not candidates for field
tests. This does not imply that minor design types are insignificant NOX
sources. For example, cyclone boilers emit 8 percent of stationary source
NOX. Yet, cyclone combustion characteristics make NOX control very
difficult. For this and other reasons, their sale has been discontinued for
other than high sodium lignite applications and it is unlikely many existing
units will be controlled for NOX. Similar considerations resulted in the
following being classified as minor design types: vertical- and stoker-fired
utility boilers, firebox and horizontal return tube package firetube boilers,
firetube stokers, and space heaters.
Control Implementation
Information on implementing NOX control was based on the control
technology background described in Section 5. Since the assessment of
current controls application is a major NOX E/A objective, the degree of
control implementation becomes a key criterion in setting source priorities.
To date, only utility boilers and gas turbines have been controlled for NOX
to any significant extent. Gas and oil units have been the most extensively
controlled, but control of coal units is increasing. Since no new gas- or
oil-fired units are being sold, NOX controls for coal units will dominate in
the future. Large and intermediate industrial boilers are also currently
controlled sources. Standards of performance for new stationary sources are
planned for these sources and 1C engines.
Nationwide Emission Ranking
Section 7.1 ranked design/fuel types by nationwide mass emissions of
NOX. These results are also shown in Table 8-5 for the specific source
categories listed. Nationwide mass emissions are useful for weighting
86
-------
TABLE 8-5. EVALUATION OF SOURCE PRIORITIES
00
-g
»
Source Category
Coal-fired utility
Oil-fired utility
Gas-fired utility
Coal-fired water-tube
Oil -fired Mtertube
Gas-fired mtertufae
Coal-fired flretutae
011 -fired flretube
Gas-fired flretube
Gas- and oil-fired
gas turbines
Gas- and oil -fired
warm air furnaces
Compression Ignition
1C engines (dlesel
fuel and mixed)
Spark Ignition
1C engines
Industrial process
combustion
Major
Design Types
In E/A Program
Tangential ,
single and
opposed wall-
flred, turbo
Same as above
Same as above
Pulv. coal,
spreader stoker
Single and
multlburner
Single and
multlburner
Scotch
Scotch
Industrial .
utility,
simple cycle
Res., Conn.
furnace
Turbocharged
Turbocharged
naturally
aspirated
Process heat-
ers, furnaces,
kilns
Minor
Design Types
In E/A Program
Cyclone,
vertical,
stoker
Cyclone
Underfeed/
overfeed
Stoker
Firebox, HRT
Firebox. HRT
Confc. cycle,
repowerlng
Space
heaters
Blower
scavenged
Degree of
Control
Implementation
All new sources, moder-
ate for existing sources
Extensive for existing
sources
Same as above
Low for existing,
Impending for new
Same as above
Same as above
Same as above
Same as above
Same as above
Moderate for existing
sources, Impending for
new sources
Increasing use for
energy conservation
Negligible for existing
sources; Impending for
new sources
Same as above
Negligible
Nationwide
NO. Emission
Ranking
1
4
3
5
10
7
14
6
9
11
12
8
2
13
Relative
Impact h
Potential0
H
N
L
H
H
L
H
M
L
L
L-M
L-M
L-M
M-H
Source
Need/Effe
Near term
H
H
H
H
H
H
M
H
H
H
H
H
H
M
Control b
:t1veness
Far term
H
L
L
H
H
M-L
L
H
M-L
H-M
H-N
M-L
M
M-H
Source
Ranking
In E/A
Program
1
3
B
2
6
11
14
5
12
4
7
10
9
13
"Major refers to sources likely to be controlled for NOx; minor refers to sources for which controls are unlikely to be Implemented In the near term.
bH high; M medium; L low
-------
relative emission contributions of various sources and detecting emission
trends independent of local variations. However, they do not account for
variations among source categories in proximity to population centers and
regional variations in the use of specific source/fuel types. These regional
factors are qualitatively included in the relative impact potential column.
Relative Impact Potential
Ranking sources by relative impact potential was based on the
multimedia emissions inventory discussed in Section 7.1, and the impact
screening to be discussed in Section 8.3. Although incremental impacts were
not considered in the evaluation, results discussed in Section 7.2 were used
to relate design type and fuel to potential for emissions of specific
pollutants when there were insufficient emission data. The proximity of
specified sources (e.g., residential furnaces) to populated areas was also
considered. The relative impact potential resulting from these considera-
tions was generally high for coal firing, medium for residual oil firing, and
low with clean fuel firing. Residential furnaces were ranked at borderline
L-M because of their proximity to populated areas and their potential for
increased emissions during cycling transients. 1C engines were also a
borderline case. Even though they fire clean fuels, organic emissions are
high. Little emission/impact data are available for industrial process
furnaces. They were related M-H on the basis of fuel use.
Effectiveness of Source Control in Air Quality Maintenance
This criterion was based on the results of the air quality screening
analysis discussed in Section 8.1. Separate consideration was given to near-
term effectiveness and far-term effectiveness to isolate effects of design
trends and growth projections for source categories. The analysis discussed
in Section 8.1 showed that control needs are highly uncertain for specific
source categories. Estimated control needs depended strongly on growth
projections, mobile source control assumptions, measurements of ambient N0£
concentrations, and the relative weighting of point sources (powerplants) and
ground level sources (mobile sources). Optimistic scenarios (in terms of
stationary source air quality impact) required only moderate control of major
stationary sources in the near term. Moderate or pessimistic scenarios,
however, required extensive near-term stationary source control. In the far
term, extensive control was generally needed regardless of assumption.
Entries in Table 8-5 were based on moderate or pessimistic scenarios. Since
the NOX E/A is largely a problem definition study, its purposes would not be
served by using optimistic assumptions on the potential for adverse impact.
For the moderate or worst case scenarios, estimated near-term control needs are
generally high for all source categories. For the far term, the needs are
focused on extensive control of new sources. Thus, sources with dwindling
new sales due to design trends or fuel availability are downgraded in the far
term.
-------
Overall Source Ranking
The last column in Table 8-5 gives the qualitative ranking of the 13
source categories. The degree of control implementation and the relative
impact potential were given the most weight. Based on this ranking, the
process and environmental assessment studies will be conducted in the
following sequence:
1. Utility and large industrial watertube boilers
2. Industrial and commercial packaged boilers
3. Gas turbines (simple cycle and combined cycle)
4. Residential and commercial warm air furnaces
5. Reciprocating internal combustion engines
6. Industrial process combustion equipment
Within each of these studies, the relative effort for specific source/fuel
categories will follow the order of ranking in Table 8-5.
Once derived, the source priorities were extended to include
consideration of specific source/control combinations. This source/control
prioritization is shown in Table 8-6. The table also shows preliminary
selection of those advanced source/control combinations which will be
evaluated in the later study of far-term applications. The prioritization of
current technology was based directly on results discussed in Section 5, and
considered the extent of current control applications to specific sources and
the cost-effectiveness of a given control compared to competitive techniques.
Major future emphasis will be given to the source/control combinations likely
to see significant control in the next 5 years. The selection of advanced
techniques for treatment in the far-term control studies was also based on
results presented in Section 5. The developmental status and schedule, as
well as the potential availability of competitive techniques were considered.
Advanced techniques which are being covered by other assessment efforts
(e.g., fluidized beds, advanced cycles) will be given minor emphasis in the
far-term effort.
8.3 POLLUTANT/IMPACT SCREENING
The list of source/control combinations given priority in Section 8.2
was further evaluated to identify specific pollutants which show potential
for an adverse environmental impact with or without NOX controls. These
results will be used to set priorities for samplng and chemical analyses to
be performed during field test programs. The emphasis in this
pollutant/impact screening was on flue gas emissions. Liquid and solid
effluent stream data were quite sparse. Future field test efforts will
attempt to resolve these insufficiencies.
89
-------
TABLE 8-6. SUMMARY OF SOURCE CONTROL PRIORITIES
Source
Ranking
1
3. 8
2
6. 11
M
5. 12
4
7
9
10
13
Source
Coal-fired utility
boilers, existing
Coal-fired utility
boilers, new
Oil-fired, gas-
fired utility
boilers
Coal -fired water-
tube. Industrial-
pulverized
Coal-fired water-
tube Industrial -
stoker
01l-f1red, gas-
fired watertube
Coal-fired fire-
tube stoker
Oil-fired, gas-
fired flretube
6as- 8 oil-fired
gas turbines
Gas- & oil-fired
warm air furnaces
Spark Ignition 1C
engines
Compression igni-
tion 1C engines
(diesel , mixed fuel )
Industrial process
combustion
NEAR TERM EFFORT IN E/A PROGRAM: CURRENT AND IMPENDING APPLICATIONS
Major Emphasis - NO E/A
Sources4 "
Tangential, opposed ft
single xall, turbo-fired
Same as above
Same as above
Single or multlburner
wall-fired
Spreader
Single or multlburner
wall -fired
Scotch
Utility, Industrial
simple cycle
Residential, commercial
furnaces
Turbocharged, natural-
ly aspirated
Turbocharged
Process heaters,
furnaces, kilns
Major NO. E/A
Emphasis - Controls
LEA, BBF, BOOS. OFA.
low-NOx burners
LEA » OFA; low-No*
burners, enlarged
firebox
LEA. BBF. BOOS. OFA,
FGR
LEA, BBF, BOOS, OFA,
low-NOx burners
LEA, OFA
LEA. OFA, low-NOx
burners
LEA, FGR. OFA, low-
NOx burners
Water Injection
Low-NOx burners
Operational tuning,
reduced Inlet air
temperature
Operational tuning
LEA, load reduction,
RAP, FGR, H?0
Injection
Minor NOX E/A
Emphasis - Sources
Cyclone, vertical
stoker
Cyclone
Underfeed/overfeed
Firebox, horizontal
return tube
Firebox, HRT
Combined cycle,
repowerlng
Space heaters
Blower scavenged
Low-NOx burners
Minor NO. E/A .
Emphasis - Controls8 >D
FGR. RAP, HzO Inj..
load reduction,
NHa Injection
FGR. RAP. H20 1nj.,
NH3 Injection
RAP. HjO Inj.. NH3
Injection
Load reduction
Load reduction
LEA
Load reduction
'Can modifications
EGR. derate
Derate
FAR TERM EFFECT:
ADVANCED TECHNOLOGY
Major NOX
E/A Emphasis
NH3 Injection
Advanced OFA
techniques;
adv. ]ow-NOx
burners, NH3
Injection
Advanced low-
NOx burners,
NH3 Injection
Advanced low-
NOx burners.
advanced OFA,
NH3 Injection
Factory
Installed
OFA. NH3 1nj.
Adv. low-NOx
burners, adv.
OFA, NH3 1nj.,
alt. fuels
Adv. low-NOx
burners, adv.
OFA, alt. fuels,
catalytic comb.
Adv. can design,
comb, cycles.
alt. fuels,
catalytic comb.
Adv. burner/
firebox des.,
alt. fuels.
catalytic comb.
Chamber redes . ,
alt. fuels
Chamber redes . ,
alt. fuels
Low-NOx burn-
ers, OFA.
alt. fuels
Minor NOx
E/A Emphasis
Flue gas treatment
Flue gas treatment:
fluldlzed beds;
adv. cycles
Chemically active
fluid bed. flue
gas treatment
Flue gas treatment
Flue gas treatment
Flue gas treatment
Exhaust gas
treatment
Exhaust gas
treatment
Major refers to sources or controls emphasized In near term control programs; minor refers to sources or controls less likely to be used.
LEA low excess air; BBF - biased burner firing; BOOS burners out of service; OFA - overflre air; FGR flue gas reclrculatlon; RAP « reduced air preheat
-------
The set of pollutant classes under consideration was described in
Section 7.2 and included carbon monoxide, vapor phase hydrocarbons,
particulates, sulfates, condensed phase organics, and trace metals. Several
of these classes were further divided into more detailed pollutant groups,
which gave a better representation of potential health/welfare hazards. For
example, the vapor phase hydrocarbon class was speciated into alkanes,
alkenes, alkynes, aldehydes, carboxylic acids, and aromatics. Sulfates,
organics, and trace metals are generally emitted as particulates, but the
particulates class was retained because it is a criteria pollutant, and
because emissions data on this class of pollutants were available.
Baseline emissions for each pollutant species group, as a function of
combustion source class, were summarized in Section 7.1. In addition,
Section 7.2 summarized the incremental emissions of these pollutant groups,
where data were available, as a function of applied NOX combustion control.
The health and welfare aspects of each species/group were discussed in
Section 3 in terms of developing maximum ambient screening concentrations. By
combining information discussed in each of those sections with a dispersion
model, it was possible to flag the pollutants from each combustion source
which represent potential environmental hazards due to applying NOX controls.
Such a summary appears in Tables 8-7 and 8-8. Table 8-7 shows
baseline emissions, typical emission levels with NOX controls, maximum
ambient screening concentrations,and derived maximum allowable emission level
(from the dispersion model) for the pollutant groups considered. The
pollutant groups listed in Table 8-7 are those for which incremental
emissions data were available. As indicated, incremental data were available
only for criteria pollutants. Table 8-8 shows a similar summary for those
pollutants groups for which little or no field data were found on the
incremental effects of NOX combustion controls.
From the data presented in Tables 8-7 and 8-8, it was possible to
identify those pollutant groups which are emitted at levels near, or
exceeding, the defined maximum allowable emission level. Pollutant
group/combustion source combinations were flagged if emission levels exceeded
10 percent of the maximum allowable level. These combinations were noted
in Tables 8-7 and 8-8, and further summarized in Table 8-9.
Table 8-9 illustrates that emissions from large coal- and oil-fired
boilers potentially represent the most significant environmental hazards.
Baseline emissions of particulates, sulfates, and certain POM species from
these source classes currently exceed the derived maximum allowable emissions
levels, while emissions of several other POM species are within an order of
magnitude of the maximum. In addition, while emissions of total vapor phase
hydrocarbons from large boilers were not identified as a concern, emissions
-of several hydrocarbon classes, notably oxygenates and aromatics, were
flagged. Finally, baseline emissions of several trace metals from coal- and
oil-fired boilers were noted as exceeding, or falling within a factor of 10
of maximum levels.
Large coal- and oil-fired boilers were not the only source class
associated with pollutant streams of concern. Incremental total vapor phase
91
-------
TABLE 8-7. COMPARISON OF POLLUTANT EMISSION LEVELS WITH NOX CONTROLS TO
MAXIMUM ALLOWABLE EMISSIONS
<£>
Pollutant Class
Carbon Monoxide
Total Vapor Phase
Hydrocarbons
Partlculates
Combustion
Source
Utility Boilers
Industrial Boilers
Residential Units
1C Engines
Gas Turbines
Utility Boilers
Industrial Boilers
Residential Units
1C Engines
Gas' Turbines
Utility Boilers
Industrial Boilers
Residential Units
1C Engines
Gas Turbines
Fuel
Natural Gas
011
Coal
All Fuels
Natural Gas
Oil
All fuels
All Fuels
Natural Gas
011
Coal
Natural Gas
Oil
Coal
Natural Gas
Oil
All Fuels
All Fuels
Natural Gas
Oil
Coal
Natural Gas
Oil
Coal
Natural Gas
Oil
Oil
01 lf Kerosene
Maximum
Ambient
Concentration
(ppb)
9,000
240
(mg/m')
0.075
Maximum
Allowable
Emission Level
(Ppm)
110.000
920,000
529,000
920.000
920,000
2.930
24,500
14.100
24.500
24,500
(g/m1)
'
0.91
7.65
4.41
7.65
7.65
Baseline
Emissions
(ppm)
23-175
25-46
23-96
0-110
40
90
90-10,300
53-970
0-35
0-30
0-40
10-25
0-15
10-90
20
25
60-4,600
0-230
(g/m1)
0.01
0.11
0.42-2.73
0.01
0.01-0.63
3.9-5.1
0.01
0.03
0.02-0.04
0.03-0.08
Emissions
with NOX
Controls
(ppm)
25-65
10-35
20-148
0-220
90-3,280
51-1.320
| 0-40
> 0-35
--
80-6,400
0-1 .200
(9/m1)
0.60-2.6
<0.03
0.02-1. 23b
7.5-10.0b
0.01
0.03
<0.26C
0.04-0.09<"
Concern
Flag"
4
44
4
44
* 4 denotes emission with NOX controls greater than 10 percent of maximum emission level.
** denotes emission with NOX controls greater than maximum emission level.
TWx control by off-sto1ch1ometr1c combustion.
"m, control by exhaust gas recInitiation.
"NO* control by derating.
-------
TABLE 8-8. COMPARISON OF BASELINE POLLUTANT EMISSION LEVELS TO
MAXIMUM ALLOWABLE EMISSIONS
1 Pollutant Class/Grauc
Vaoor Phase Hydrocarbons3
AUanes
Alkenes
Alkynes
Aldehydes
Carboxylic Acids
Aromatics (benzene
and one-ring
derivatives)
Sul fates
Organ lc_s_ (POM1 5)
Anthracene
Pnenanthrene
^o-cus-.ion acu-cs
Utility Boilers
Industrial Boilers
Util ity Boilers
industrial Boilers
Utility Boilers
Industrial Boilers
Utility Boilers
Industrial Boilers
Utility Boilers
Utility Boilers
Utility Boilers
Utility Sailers
Industrial Boilers
Resident* il Units
Utility Boilers
Industr'a' Boilers
Residential Units
Fuel
Natural Gas
Oil
Coal
Oil
Coal
'latjral Us
nil
Coal
Oil
Coal
Natural Gas
Oil
Cojl
Oil
Coal
Natural Gas
Oil
Coal
Gil
Oil'
Coal
Natural Gas
Oil
Coal
Natural Gas
Oil
Coal
Coat
Oil
Coal
Coal
Coal
Natural Ga>
Oil
Coal
Coal
M.I.IMUIII
AmBient
Concentration
4.420
59.500
62.700
2.1
13
O.OC2
.-«/
0.002
(ppt)
0.14
4.0CO
Allowable
Emission Level
(ppm)
54.000
450.000
725,000
'Jnl inited
765.900
Jnl inited
25.6
214
159
0.324
(9/-'l
0.024
(ppo)
1.71
14.3
8.2
50.000
4ZO.OOO
240.000
Baseline
Enissions
(ppra)
.80
<40
<150
-80
<40
<150
<5
<5
10
5
5
2.5-200
2.5
6-12
200
<20
'30
-------
TABLE 8-8. Continued
Pollutant Class/Group
Organics (POH's) (Cont.)
Fluoranthrene
Pyrene
Eenzo(a)pyrene
Benzo(e)pyrene
Perylene
Trace Hetajs
As
E
Ba
Be
BT -
Cd
Co
Co*ustion Source
Ut11«t> Boilers
Industrial Boilers
Residential Units
Utiliij Boilers
industrial boilers
Residential Units
Utility Boilers
Industrial Boilers
Residential Units
Utility Boilers
Industrial Boilers
Residential Units
Utility Boilers
Industrial Boilers
Residential Units
I'tility Boilers
Fuel
Coal
Natural Gas
Oil
Coal
Coal
Coal
Natural Gas
Oil
Coal
Coal
Coal
Natural Gas
Oil
Coal
Coal
Coal
Natural Gas
Coal
Coal
Coal
lot'
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Coal
Coal
Oil
Coal
Oi'
Coal
Har ifnum '
Ambient
Concentration
(PPt)
10,900
*
0.12'.
0.097
0.097
0.097
lug/m'}
0.825
16.5
0.825
0.0033
16
0.00825
0.165
Kanirufl!
Allowable
Eir.issioti Level
(ppb)
133.000
1.110.00C'
"' 641,000
1.46
12. 4
7.1
1.2
9.9
5.7
1.2
9.9
5.7
1.2
9.9
5.7
(mg/m'l
10.1
201
10.1
0.04
"
195
1.01
2.0
Baseline
Eriisions
(ppb)
0.003-0.5
0.04-3.4
O.OZ-1.8
0.8-10
13-350
0.01-0.5
0.5-7.5
0. 005-2. Z
0.6-4.5
2-2,500
0.003-0.1
0.006-0.1
0.006-0.3
0.007-2.2
O.OOS-800
0.007-0.15
0.006-0.5
0.02-1.7
1-330
0.005-0.015
0.35
0.1-770
(mg/m1)
0.004
0.45
0.068
3.43
0.52
0.65
0.52
0.03
0.006
0.12
0.27
C.ll
Concern
flag'
4
+
+
+
H-
+
++
f
4
++
+4
++
i /
1 f
4
4
denotes baseline emissions exceec U> :-crt?nt of mo>i-^.T, allowable level
»+ denotes baseline erissions PXC.C-CE! rjxmo- allowaiilc level
94
-------
TABLE 8-8. Concluded
Pollutant Class/Group
Trace Metal s fCont.l
Cr
Cu
- _ .
Kg
Hn
u
Ho
Hi
Pb
Sfa
Se
V
Zn
IT
Ci": jstion Source
Utility Boilers
Fuel
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
Oil
Coal
fc : lent
CC'i.tntranon
i-.g/ir1)
0.001
1.65
«,.
16.5
8.25
6.25
0.165
0.247
0.825
0.33
0.825
1.65
8.2
Ailoatle
'-?/*)
:.oi2
20.1
201
101
101
2.0
3.0
10.1
4.0
10.1
20.1
100
Baseline
Emissions
img/c')
0.6E
O.tS
1.20
0.006
Q.c3
0.55
1.58
0.55
0.25
32
0.68
0.62
0.59
O.QO«
0.04
0.632
O.T73
_
47.:
1.20
0.87
9.3£
0.17
0.86
C°fV/-an
^.*
1
+*
+
+
,
-.
4-i
*»
4-
* + denotes baseline emissions exceed 10 percent of maximum allowable level
+* denotes baseline emissions exceed maxiiajrr allowable level
95
-------
TABLE 8-9. SUMMARY OF POTENTIAL POLLUTANT/COMBUSTION SOURCE HAZARDS
Pollutant Class/Group
Vapor Phase Hydrocarbons
Total
Aldehydes
Car boxy He Adds
One-Ring Aromatics
Particulates
.Sul fates
Organlcs
Anthracene
Pyrene
Benzo(a)pyrene
Benzo(e)pyrene
Perylene
Trace Metals
Be
Cd
Co
Cr
Ni
Pb
V
Zn
Combustion Source
1C Engines
Utility Boilers, all Fuels
Oil-Fired Industrial Boilers
Coal -Fired Utility Boilers
Utility Boilers, all Fuels
CoaKFired Boilers
011-Fired Industrial Boilers
Coal- and Oil-Fired Utility
Boilers
Oil-Fired Boilers
Coal-Fired Residential Units
Coal -Fired Utility Boilers
Coal -Fired Residential Units
Boilers, all Fuels
Coal -Fired Residential Units
Coal -Fired Industrial Boilers
Coal-Fired Residential Units
Coal-Fired Boilers
Coal -Fired Residential Units
Coal -Fired Utility Boilers
Coal-Fired Utility Boilers
on-F1red Utility Boilers
Coal- and Oil -Fired Utility
Boilers
On-F1red Utility Boilers
Coal-Fired Utility Boilers
Coal- and Oil-Fired Utility
Boilers
011-Fired Utility Boilers
Coal-Fired Utility Boilers
Coal-Fired Utility Boilers
Emission Exceeds
Potential Hazard
Threshold
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Emission Exceeds
10% of Potential
Hazard Threshold
X
X
X
X
X
X
X
X
X
X
X
X
X
ID
CM
I
96
-------
hydrocarbon emissions from 1C engines operating with dry NOX controls exceeded
10 percent of maximum allowable emissions and therefore represent another
concern. In addition, baseline emissions of several organics from
residential coal stokers exceeded maximum limits. However, since the use of
coal firing in residential heating applications is declining, this
source/pollutant combination will not be considered a priority concern.
Based on the information presented in Table 8-9, further efforts will
be directed toward studying NOX controls which could increase emissions of:
Participates from coal- and oil-fired boilers, e.g., off- stoichiometric
combustion (OSC), flue gas recirculation (FGR), and ammonia injection
(NH3)
Sulfates from coal- and oil-fired boilers, e.g., OSC, FGR, and
NH3
Organics from coal- and oil-fired boilers, e.g., low excess air
(LEA), OSC, and FGR
Segregating trace metals from coal- and oil-fired boilers, e.g.,
LEA, OSC, and FGR
Vapor phase hydrocarbons emissions from 1C engines, e.g., all
controls
It is important to note that these results were based only on
relatively qualitative screening efforts. Future activities will strive to
strengthen the potential impact analyses by applying source analysis modeling
as discussed in Section 4.
97
-------
SECTION 9
TECHNOLOGY TRANSFER
The NOX E/A is largely a technology synthesis program. As such, it
draws heavily on technology in related areas such as environmental sciences
and environmental health. The NOX E/A, in turn, generates technology for use
by control developers, users, and regulatory groups. This section highlights
the input and output technology transfer activities in the program.
During the first year, the NOX E/A evaluated the input data resources
available to conduct the process and environmental assessment studies. A
number of areas of insufficient data were identified. Further R&D in these
areas would significantly benefit the environmental assessment effort. Since
this R&D is beyond the scope of the NOX E/A program, data gaps and supporting
R&D needs were summarized in previous sections of this report, and in greater
depth in the preliminary assessment (Reference 16). These are summarized
below for the key supporting areas of the NOX E/A.
Process Technology Background
Population and design trends in industrial process combustion
Occurrence and process characteristic of nonstandard operation
for all equipment types
Prevalence of mixed and alternate fuel use in utilities
and industrial applications
Environmental Background
-- Impacts of combustion-generated pollutants on human health
and aquatic ecology
Impacts of short-term and chronic exposure to N02 and
secondary pollutants formed from
-- Cross-media impacts
Environmental Data Acquisition
Sampling and analysis procedures for organ ics and met allies
99
-------
-- Emissions for transient and nonstandard operation
Emissions for combustion-generated liquid and solid effluents
Environmental Alternatives Analysis
-- Long range transport of nitrate and ozone
-- Atmospheric chemistry of the formation of secondary pollutants
from combustion generated primary pollutants
In addition, there are a number of other data gaps and R&D needs in the
control technology area which are being addressed within the program.
The primary program output during the first year was the Preliminary
Environmental Assessment Report (Reference 16). This report documents the
methodologies and supporting data on source and process characterization,
multimedia pollutant emissions, and impact assessments, and sets priorities
on sources and combustion modification controls for further study. Other
activities in technology transfer are as follows:
Preparation of "NOX Control Review", a quarterly technology status
report on NOX control development and implementation and regulatory
strategy
Coordination of the Second Symposium on Stationary Source Combustion
held in New Orleans, August 29-September 1, 1977
t Documentation of the status of IERL developmental programs in combustion
modifications for use in the IERL annual report
Development of Source Analysis Models and Effluent Transformation
and Transportation Analysis for use in the EACD environmental assessments
100
-------
SECTION 10
FUTURE EFFORTS
During the second year of the NOX E/A program, effort will center on
preparation of process and impact assessment studies for the major source
categories. These studies will involve process calculations of specific
combustion modification/source combinations, detailed cost calculations of
retrofit and new design controls and assessments of multimedia impacts and
operational impact from control use. Utility boilers will be studied first,
followed by industrial boilers and gas turbines. To support these studies,
a major effort will be devoted to source testing. Multimedia emissions
before and after the use of NOX controls will be sampled and analyzed for the
major source/control combinations. Additional support for the impact
assessments will be provided by the baseline source analysis study. This
study will compare ground level pollutant concentrations from sources
uncontrolled for NOX to the Multimedia Environmental Goals, denoting the
threshold of potentially hazardous impacts.
The results of the above efforts will be integrated in the
environmental alternatives analysis. As new results on process cost and
impact are available, they will be used with the systems analysis model to
update the evaluations of the extent of need for combustion modification
technology in the future.
101
-------
REFERENCES
1. Crenshaw, J. and A. Basala, "Analysis of Control Strategies to Attain
the National Ambient Air Quality Standard for Nitrogen Dioxide,"
presented at the Washington Operation Research Council's Third Cost
Effectiveness Seminar, Gaithersburg, MD, March 18-19, 1974.
2. "Air Quality, Noise and Health Report of a Panel of the Interagency
Task Force on Motor Vehicle Goals Beyond 1980," Department of
Transportation, March 1976.
3. McCutchen, G. D., "NOX Emission Trends and Federal Regulation,"
presented at AIChE 69th Annual Meeting, Chicago, November 28 - December
2, 1976.
4. "Air Program Strategy for Attainment and Maintenance of Ambient Air
Quality Standards and Control of Other Pollutants," Draft Report, U.S.
EPA, Washington, October 18, 1976.
5. "Annual Environmental Analysis Report, Volume 1 Technical Summary," The
MITRE Corporation, MTR-7626, September 1977.
6. Personal communication with R. Bauman, Strategies and Air Standards
Division, Office of Air Quality Planning and Standards, U.S. EPA,
October 1977.
7. "An Analysis of Alternative Motor Vehicle Emission Standards," U.S.
Dept. of Transportation/U.S. EPA/U.S. FEA, May 1977.
8. French, J. G., "Health Effects from Exposure to Oxides of Nitrogen,"
presented at the 69th Annual Meeting, AIChE, Chicago, Illinois, November
1976.
9. "Scientific and Technical Data Base for Criteria and Hazardous Pollutants
1975 EPA/RTP Review," EPA-600/1-76-023, NTIS-PB 253 942/AS, Health
Effects Research Laboratory, U.S. EPA, January 1976.
10. Shy, C. M., "The Health Implications of an Non-Attainment Policy,
Mandated Auto Emission Standards, and a Non-Significant Deterioration
Policy," presented to Committee on Environment and Public Works, Serial
95-H7, February 10, 1977.
11. "Report on Air Quality Criteria for Nitrogen Oxides," AP-84, Science
Advisory Board, U.S. EPA, June 1976.
12. "Control Strategy for Nitrogen Oxides," Memo from B. J. Steigerwald,
Office of Air Quality Planning and Standards, September 1976.
13. "Report on Air Quality Criteria: General Comments and Recommendations,"
Report to the U.S. EPA by the National Air Quality Advisory Committee of
the Science Advisory Board, June 1976.
103
-------
14. Personal communication with M. Jones, Strategies and Air Standards
Division, Pollutant Strategies Branch, September 15, 1976.
15. "Control of Photochemical Oxidants Technical Basis and Implications
of Recent Findings," EPA-450/2-75-005, Office of Air and Waste
Management, OAQPS, July 1975.
16. "Preliminary Environmental Assessment of the Application of Combustion
Modification Technology to Control Pollutant Emissions from Major
Stationary Combustion Sources," Vols. I & II, Aerotherm TR-77-28, Acurex
Corporation, February 1977.
17. Dupree, W. 6. and J. S. Corsentino, "Energy Through the Year 2000
(Revised)," Bureau of Mines, December 1975.
18. Handy, R. and A. Schlinder, "Estimation of Permissible Concentrations of
Pollutants for Continuous Exposure," Research Triangle Institute, EPA-
600/2-76-155, NTIS-PB 253 959/AS, June 1976.
19. Cleland, J. G. and G. L. Kingsbury, "Multimedia Environmental Goals for
Environmental Assessment (Draft)," Research Triangle Institute, January
1977.
20. Schalit, L. M. and K. J. Wolfe, "SAM I/A: A Rapid Screening Method for
Environmental Assessment of Fossil Energy Process Effluents," Aerotherm
Draft Report TR-76-50, Acurex Corporation, August 1977.
21. Personal communication, Mr. Alan Hoffman, Chief Monitoring Section, U.S.
EPA, October 1, 1976.
22. Frey, D. J., "De-Ashed Coal Combustion Study," Combustion Engineering,
Inc., October 1964.
23. Waitzman, D. A., et al., "Evaluation of Fixed-Bed Low-Btu Coal
Gasification Systems for Retrofitting Power Plants," EPRI Interim Report
203-1, Electric Power Research Institute, February 1975.
24. Shimizu, A. B., et al., "NOX Combustion Control Methods and Costs for
Sources; Summary Study," EPA-600/2-75-046, NTIS-PB 246 750/AS,
September 1975.
25. "Monitoring and Air Quality Trends Report, 1974," EPA-450/1-76-001, EPA
Office of Air Quality Planning and Standards, February 1976.
26. Personal communication with C. Masser, National Emissions Data System
(NEDS), October 1976.
27. Information from National Emissions Data System (NEDS), October 26,
1976.
28. Hamersma, J. W., et al., "IERL-RTP Procedures Manual: Level 1 Environmental
Assessment," EPA-600/2-76-160a, NTIS-PB 257 850/AS, TRW, June 1976.
104
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TECHNICAL REPORT DATA
e read fiittnictioiis on llic reverse he lore completing)
NO.
EPA-600/7-78-046
-I. TITLE AMD SUBTITLE
Environmental Assessment of Stationary Source NOx
Control Technologies: First Annual Report
6. PERFORMING ORGANIZATION CODE
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
March 1978
7. AUTHORS L R >Waterland, H.B. Mason, R.M.Evans,
K. G.Salvesen, and K.J.Wolfe
8 PERFORMING ORGANIZATION REPORT NO
TR-77-58
(Aerotherm Project 7241)
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Acurex Corporation/Aerotherm Division
485 Clyde Avenue
Mountain View, California 94042
10. PROGRAM ELEMENT NO.
EHE624A
11. CONTRACT/GRANT NO.
68-02-2160
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Annual; 6/76-6/77
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES IERL-RTP project officer is Joshua S. Bowen, Mail Drop 65,
919/541-2470.
is. ABSTRAc-npne r8pOrt summarizes results of the first year of an environmental
assessment program for stationary NOx combustion modification technologies. The
first-year effort concentrated-on: (1) developing the methodology for environmental
assessment and process engineering studies: (2) compiling data on source process
characteristics, emissions, and pollutant impacts: and (3) setting program priorities
on sources, controls, pollutants, and impacts. The report reviews each area and
summarizes plans for future efforts. It discusses program results and plans for
stationary NOx source equipment characterization, environmental goals compilation,
source analysis model development, NOx control technology characterization,
process engineering methodology development, baseline multimedia emissions
inventory compilation, and systems analysis model development and use.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b-IDENTIFIERS/OPEN ENDED TERMS
c. COSATl Held/Group
Air Pollution
Combustion
Combustion Control
Nitrogen Oxides
Criteria
Contaminants
Operating Costs
Boilers
Gas Turbines
Internal Combus
tion Engines
Assessments
Air Pollution Control
Stationary Sources
Combustion Modification
Criteria Pollutants
Emission Factors
Control Costs
13B
2 IB
07B
14A,05A
13A
13G
21G
14B
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
112
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
105
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