EFtt
United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/2-79-019a
Laboratory January 1979
Research Triangle Park NC 27711
Research and Development
Source Assessment:
Residential Combustion
of Coal
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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 ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
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This document is available to the public through the National Technical Informa-
tion Service. Springfield, Virginia 22161.
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EPA-600/2-79-019a
January 1979
Source Assessment:
Residential Combustion of Coal
by
D.G. DeAngelis and R.B. Reznik
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
Contract No. 68-02-1874
Program Element No. 1AB015
EPA Project Officer: Ronald A. Venezia
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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PREFACE
The Industrial Environmental Research Laboratory (IERL) of the
U.S. Environmental Protection Agency (EPA) has the responsibility
for insuring that pollution control technology is available for
stationary sources to meet the requirements of the Clean Air Act,
the Federal Water Pollution Control Act, and solid waste legis-
lation. If control technology is unavailable, inadequate, or
uneconomical, then financial support is provided for the develop-
ment of the needed control techniques for industrial and extrac-
tive process industries. Approaches considered include: process
modifications, feedstock modifications, add-on control devices,
and complete process substitution. The scale of the control
technology programs ranges from bench- to full-scale demonstra-
tion plants.
The Chemical Processes Branch of the Industrial Processes
Division of IERL has the responsibility for programs to develop
control technology for a large number of operations (more than
500) in the chemical industries. As in any technical program,
the first question to answer is, "Where are the unsolved
problems?" This is a determination which should not be made on
superficial information; consequently, each of the industries is
being evaluated in detail to determine if there is, in EPA's
judgment, sufficient need for emissions reduction. This report
contains the data necessary to make that decision for the air
emissions from the residential combustion of coal.
Monsanto Research Corporation has contracted with EPA to inves-
tigate the environmental impact of various industries which
represent sources of pollution in accordance with EPA's respon-
sibility as outlined above. Dr. Robert C. Binning serves as
Program Manager in this overall program, entitled "Source
Assessment," which includes the investigation of sources in each
of four categories: combustion, organic materials, inorganic
materials, and open sources. Dr. Dale A. Denny of the Industrial
Processes Division at Research Triangle Park serves as EPA Pro-
ject Officer. In this study of the residential combustion of
coal, Dr. Ronald A. Venezia served as EPA Task Officer.
iii
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ABSTRACT
This report summarizes the assessment of air emissions from the
residential combustion of coal and includes some discussion of
solid residues and the leaching of these materials. The report
covers anthracite, bituminous, and lignite coals, with primary
emphasis on bituminous coals because they represent approximately
70% of residential coal combustion.
Approximately 2.6 million metric tons of coal were burned as a
primary source of heat in an estimated 493,018 housing units in
1974. Geographical distribution of coal-fired heating devices
is related to the location of major coal fields. States in the
Appalachian coal region account for 72% of the residential com-
bustion units burning bituminous coal. Homes burning anthracite
are confined to Pennsylvania and the east coast, while those
burning lignite are located in North Dakota. From 1974 to 1975
residential coal usage increased by 50% in the West and declined
25% in the remaining regions.
Stoker-fed boilers and warm-air furnaces are currently being
marketed for burning coal as a primary source of heat in resi-
dential structures; however, hand-fed units and room heaters also
exist. Emissions from these units include particulates, sulfur
oxides, nitrogen oxides, carbon monoxide, hydrocarbons, poly-
cyclic organic material (POM), and trace elements. The severities
of these emissions were assessed for an average source. Emissions
of POM's were found to have a severity of 2.6 for combustion of
bituminous coal while the remaining emissions had severities of
0.05 or less.
A special assessment of the environmental impact of an array of
100 houses burning coal indicates the potential for a thirtyfold
increase in the severities of associated emissions. In this case,
the severities were greater than 0.05 for 16 individual elements
and 4 criteria pollutants; severities were 91 and 1.7 for POM in
bituminous and anthracite coal burning, respectively.
This report was submitted in partial fulfillment of Contract No.
68-02-1874 by Monsanto Research Corporation under the sponsorship
of the U.S. Environmental Protection Agency and covers the period
November 1976 to November 1978.
IV
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CONTENTS
Preface iii
Abstract iv
Figures vi
Tables vii
Abbreviations and Symbols x
1. Introduction 1
2. Summary 3
3. Source Description 11
Source definition 12
Equipment description 12
Fuel characteristics 20
Average source definition 23
Combustion process 28
Geographical distribution 31
4. Emissions 37
Air emissions 37
Solid residues 59
Potential water pollutants . 61
Potential environmental effects 62
5. Control Technology 76
6. Growth and Nature of the Source 79
References 83
Appendices
A. Determination of representative sources 91
B. Estimation of the source population
and fuel consumption 96
C. Derivation of emission factors 100
D. POM emission factors for various fossil-
fueled boilers and furnaces 110
E. Derivation of source severity and
affected population equations Ill
F. Total coal-fired residential
combustion emissions 124
Glossary 129
Conversion Factors and Metric Prefixes 132
v
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FIGURES
Number Pagt
1 Stoker-fed residential coal-fired boiler 13
2 Cutaway view of stoker-fired residential furnace ... 13
3 Hand-fed room heater for burning coal or wood .... 13
4 Schematic of automatic coal-fired residential
heating system for boiler or air furnace 15
5 Will-Hurt stoker assembly 18
6 Combustion of a solid 29
7 Underfeed arrangement of a solid fuel bed 30
8 Overfeed arrangement of a solid fuel bed 30
9 Location of U.S. coal fields 35
10 Estimated residential coal consumption in 1974
by state 36
11 Effect of coal sulfur content on SOX emissions .... 48
12 Housing arrangement for the evaluation of multiple
residential coal-fired sources 67
13 Isopleth diagram representing ambient
concentration profiles as percent of maximum .... 68
14 Variation of x/F with distance 69
15 Residential coal-firing heating trends 79
16 Shipments of coal- and wood-fired residential
heating devices 80
VI
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TABLES
Number Page
1 Criteria Emissions, from Coal-Fired Residential
Heating Equipment 4
2 Noncriteria Pollutant Emissions from Coal-Fired
Residential Combustion 5
3 Source Severities for Coal-Fired Residential
Combustion Emissions 8
4 Source Severities for Coal-Fired Residential Combustion
Emissions from Multiple Sources 9
5 Population Exposed to Emissions from Average Coal-Fired
Residential Heating Devices 10
6 Housing Units Heated by a Particular Fuel 11
7 Average Composition of Coal, Heating Value, and
Free Swelling Index 22
8 Average Concentration of 36 Elements in Coal 23
9 Arithmetic Mean of Proximate and Ultimate Analyses
and Elemental Composition for Appalachian
Coal Region Samples 25
10 Arithmetic Mean of Proximate and Ultimate Analyses
and Elemental Composition for Pennsylvania
Anthracite Region Samples 26
11 Arithmetic Mean of Proximate and Ultimate Analyses
and Elemental Composition for North Dakota
Lignite Coal Samples 27
12 Estimated Population of Coal-Fired Primary
Residential Heating Devices 33
13 Estimated Distribution of Coal Used for Residential
Combustion, 1974 34
14 Average Uncontrolled Emission Factors for Automatic
Coal-Fired Residential Combustion . 39
15 Emission Factors for Coal-Fired Residential
Combustion as Compared to Those in AP-42 40
vii
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TABLES (continued)
Number Page
16 Emission Factors for Residential Size Bituminous
Coal Combustion Units from Individual
Test Programs 41
17 Average Carbon, Hydrogen, and Nitrogen Content of
Particulate Emissions from Coal-Fired Residential
Heating Systems 4?
18 Major Organic Spec.ies Emitted from Residential
Combustion of Bituminous Coal 50
19 Analysis of Coal Tar Samples from Coal
Gasification Process 51
20 POM Emission Factors from Coal-Fired Residential
CombustionCompared to Other Combustion Sources ... 52
21 Emission Factors for Individual Elements from
Bituminous Coal-Fired Residential
Heating Equipment 54
22 Fraction of Elements in Coal Emitted to the Atmosphere
During Residential Combustion 55
23 Classification of Elements According to Their
Partitioning Behavior 56
24 Average Emission Rates for a 20-Minute ON and
40-Minute OFF Heating Cycle of a Residential
Bituminous Coal-Fired Combustion Unit 58
25 Ash Residue from Combustion of Bituminous Coal in
a Warm-Air Furnace 60
26 Concentration of Elements in the Ash Residue from
a Bituminous Coal-Fired Warm-Air Furnace 60
27 Relative Leachability of Individual Elements from
Coal-Fired Residential Combustion Residue 61
28 Ambient Air Quality Standards for Criteria
Pollutants 64
29 Threshold Limit Values Used for Noncriteria
Pollutants 65
30 Source Severities for Emissions from Average,
Automatic, Coal-Fired Residential Combustion Units . 66
31 Source Severities for Coal-Fired Residential
Combustion Emissions from a Multiple Source Array . .70
32 Affected Population for Single Source Emissions .... 71
33 Population Affected by Emissions from Multiple
Sources 73
viii
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TABLES (continued)
Number
34 Estimated Annual Criteria Emissions and Burden from
Coal-Fired Residential Combustion for 1974 73
35 Total Annual Emissions of Criteria Pollutants from
Residential Combustion Sources 74
36 Combustion Control Strategies for Reducing Air
Pollutants from Residential Heating
Equipment 78
37 Effect of Boron Trifluoride on Free Swelling Index
and Volatile Matter of High Volatile
Bituminous Coals 78
IX
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ABBREVIATIONS AND SYMBOLS
AR —Q/aciru
a,b,c,
d,f — constants (Appendix E)
BD H2/2c2
R
C, D — atmospheric stability classes
e — 2.72
F — hazard factor, g/m3
H — emission height, m
Nma — volume in cubic meters at standard conditions
(i.e., 0°C and 1 atm)
PCS — polychlorinated biphenyl
POM — polynuclear organic material
ppm — parts per million
Q — emission rate, g/s
Q. — emission rate for species i, g/s
Q — emission rate of reference species, g/s
S — source severity
t — averaging time, min
t — short-term averaging time of 3 min
u — national average wind speed, 4.5 m/s
u — average wind speed, m/s
V, — stack gas volume during ON segment of heating
cycle, m3
V2 — stack gas volume during OFF segment of heating
cycle, m3
x — downwind dispersion distance from source of emission
release, m
x-i, xa — distance from the source where x/F equals 1.0 or
0.05, m
y — horizontal distance from centerline of dispersion, m
TI — 3.14
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ABBREVIATIONS AND SYMBOLS (continued)
max
max, i
max, o
standard deviation of horizontal dispersion, m
standard deviation of vertical dispersion, m
downwind ground level concentration at reference
coordinate (x, y), g/m3
time-averaged ground level concentration, g/m3
maximum ground level concentration, g/m3
time-averaged maximum ground level concentration,
g/m3
time-averaged maximum ground level concentration
of species i, g/m3
time-averaged maximum ground level concentration
of reference species, g/m3
XI
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SECTION 1
INTRODUCTION
The majority of homes within the United States are now heated by
either natural gas (56%) or fuel oil (24%). These fuels have
traditionally been inexpensive, easy to obtain, clean, and simple
to burn in home furnaces. However, as natural gas and oil
reserves diminish, it has become apparent that alternate energy
sources must be developed for the residential sector. One candi-
date replacement fuel is coal.
Coal is the nation's most plentiful fuel, and in the past it was
the predominant home heating fuel. At the present time, about 1%
of the nation's homes are heated with coal. Recent advances in
furnace design have made coal-fired residential furnaces easier to
operate and nearly automatic. Consequently, the use of coal for
home heating is attractive both economically and technically, and
there are indications in some regions of the country of a trend
toward increased home heating with coal.
One major drawback to residential coal combustion is increased
air pollution. Both natural gas and fuel oil are cleaner fuels
because they produce lower levels of pollutants than coal when
burned in home heating devices. As a result, both regional and
national EPA officials have become concerned over the potential
environmental impact from increased residential coal combustion.
A major changeover from natural gas or fuel oil to coal could
produce a dramatic adverse effect on local air quality. For
example, it is known that certain gases, trace elements, and
organic compounds can have serious health effects in relatively
low concentrations and that these materials are potential emis-
sions from coal combustion sources.
This report presents a detailed characterization of emissions
from residential coal combustion and an evaluation of their
potential environmental effects. It describes the various types
of combustion equipment, the present geographic distribution of
coal-fired heating equipment, the different fuel types, and the
combustion chemistry. Emission control technology and possible
future trends of the source are also discussed.
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Residential combustion of coal has been divided into the follow-
ing categories:
• Residential combustion of anthracite coal
• Residential combustion of bituminous coal
• Residential combustion of lignite coal
These three source types are treated simultaneously in this re-
port because of similarities in equipment, combustion conditions,
and process emissions.
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SECTION 2
SUMMARY
This report assesses the environmental impact of air emissions
and solid residues produced by the residential combustion of
coal, including anthracite, bituminous and lignite coal types.
Estimated 1974 residential consumption of coal for primary heat-
ing was 2,610,000 metric tons;9 850,000 metric tons of anthra-
cite, 1,740,000 metric tons of bituminous, and 20,000 metric tons
of lignite. Coal was burned in approximately 490,000 heating
devices located in all 50 states. Lignite is burned for residen-
tial purposes in North Dakota only; anthracite combustion is
limited to northern states east of the Mississippi River with 64%
in Pennsylvania; and bituminous coal is burned in every state
except Connecticut, Delaware, Maine, Maryland, New Hampshire, New
Jersey, North Dakota, Rhode Island, and Vermont. About 70% of all
residential coal heating devices are located in the Appalachian
coal region including the states of Alabama, Kentucky, Maryland,
Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia.
Pennsylvania alone has 28% of all coal-fired heating units and
accounts for 30% of total residential coal consumption.
Coal-fired residential combustion sources are defined as those
devices used to burn bituminous, anthracite and lignite coals to
generate household heat. They are limited to units in occupied
structures containing one or two housing units and generating up
to 420 MJ/hr of heat. In 1970 about 55% of coal-fired residential
primary heating devices were boilers and warm-air furnaces; the
remaining units were heating stoves. Boilers and warm-air fur-
naces are usually stoker fed and are automatically controlled by
a thermostat. They are generally designed to burn specific coal
types. Other types of equipment used for residential coal com-
bustion, especially for auxiliary heating, include room heaters,
metal stoves, and metal and masonry fireplaces. These devices
are generally less sophisticated and less energy efficient than
boilers and furnaces.
The automatic stoker is the main component of automatic coal-
fired heating units (i.e., boilers and warm-air furnaces). It
consists of a hopper to store coal, a worm-fed mechanism to
1 metric ton = 106 grams; conversion factors and metric system
prefixes are presented at the end of this report.
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deliver coal for combustion, a retort where the coal burns, and
a forced-draft fan that provides combustion air. The stoker is
operated by a thermostat that activates the coal feed mechanism
and combustion air fan when there is a demand for household heat.
When the stoker is off, coal continues to burn slowly by natural
draft combustion. A representative burning pattern for automatic
combustion units is a total of 20 minutes of stoker operation and
40 minutes of natural draft combustion during each hour. The
stoker design, method of operation, and use-burning cycle are
significant parameters in determining the nature of emissions from
automatic coal-fired heating devices. The design of the boiler
or furnace used to recover heat is also important in the genera-
tion of emissions.
The composition and physical properties of coal, such as sulfur
content, elemental content, volatile matter content, and free
swelling index, are the other important factors in combustion-
generated emissions. These properties can vary widely from one
coal region to another. For example, coal trace element content
ranges as much as two orders of magnitude for different bitumi-
nous coal types.
Residental combustion of coal produces emissions of particu-
lates, sulfur oxides (SO ), nitrogen oxides (NO ), hydrocarbons
[including polycyclic organic materials (POM's)f, carbon monoxide
(CO), and trace elements. Uncontrolled mass emissions and emis-
sion factors are listed in Tables 1 and 2. Also presented are
TABLE 1. CRITERIA POLLUTANT EMISSIONS FROM COAL-
FIRED RESIDENTIAL HEATING EQUIPMENT
Emission factor.
Total annual emissions,
metric tons/yr
Percent of national
emissions, from all
Species
Particulates
S0x
N0x
Hydrocarbons
CO
Bitu-
minous
5.1
15.0 SC
3.9
1.8
13.0
Anthra-
cite
1.1
12.0 Sc
0.9
1.3
8.3
Lignite
13.0
15.0 Sc
3.0
0.5
1.0
Bitu-
minous
15,616
73,443d
6,035
6,495
65,104
Anthra-
cite
937
6,916d
769
1,110
7,088
Lignite
244
423d
56
9
19
Bitu-
minous
0.08
0.2
0.02
0.2
0.05
Anthra-
teite
<0.01
0.02
<0.01
<0.01
0.01
Lignite
<0.01
<0.01
<0.01
<0.01
<0.01
Average for automatic units.
Grams of pollutant per kilogram of fuel.
S is sulfur content of coal expressed as percent.
Baaed on average sulfur content of coals used by each state.
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TABLE 2. NONCRITERIA POLLUTANT EMISSIONS FROM
COAL-FIRED RESIDENTIAL COMBUSTION*
(g of pollutant/kg of fuel burned)
Emission Factor
Species
Organic species:
Polycyclic organic
materials
Polychlorinated
biphenyls
Formaldehyde
Elements:
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Bituminous
0.058
<0. 00005
0.0012
1.6
0.0008
0.02
0.01
0.0002
0.00001
0.003
0.01
0.0005
0.12
0.72
0.002
0.0007
0.002
0.08
0.005
1.9
0.01
0.003
0.07
0.06
0.0002
0.002
0.002
0.0005
0.009
0.23
0.0005
0.004
2.7
0.00002
0.03
0.01
0.0002
0.00008
0.0005
0.0002
0.09
0.0001
0.002
0.001
0.001
0.02
0.005
Anthracite
0.001
2.0
0.0007
0.005
0.01
0.0002
0.00001
0.0001
0.001
0.0002
0.07
1.5
0.002
0.0007
0.003
0.06
0.005
0.44
0.008
0.003
0.06
0.002
0.0002
0.002
0.002
0.0003
0.008
0.24
0.0005
0.003
2.7
0.002
0.05
0.01
0.00005
0.004
0.0003
0.0001
0.15
0.0002
0.002
0.001
0.0001
0.012
0.005
Lignite
3.7
0.0002
0.005
0.04
0.00002
0.01
0.00008
1.2
0.17
0.0002
0.0001
0.0005
0.03
0.0008
1.3
0.002
0.0002
0.34
0.005
0.002
0.002
0.0002
0.0002
0.03
0.02
0.0001
0.0006
0.85
0.001
0.36
0.03
0.0004
0.00004
0.03
0.00007
0.0004
0.00002
0.0003
0.002
0.001
Blanks indicate data not available.
Calculated values based on coal composition and limited test
data.
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the contributions of coal-fired residential combustion to national
levels of criteria pollutant emissions (i.e., particulates, SO ,
NO , CO, and hydrocarbons). Sulfur oxide emissions from residen-
tial combustion of bituminous coal represent the greatest contri-
bution to national criteria pollutant emissions from residential
coal combustion. Residential combustion of lignite coal does not
make a significant contribution to the national emission burden
because this source is limited to North Dakota. Criteria pollut-
ant emissions from residential bituminous combustion exceed 1% of
the state totals in three states, while anthracite and lignite
combustion criteria'pollutant emissions are all less than 1% in
every state, with most being less than 0.1%.
While the criteria pollutants emitted annually from residential
coal combustion are a relatively small fraction of the total annu-
al emissions of these pollutants, the emissions of POM's from this
emission source may be significant. Annual emissions of POM's
nationally in 1974 were about 101 metric tons from automatic bitu-
minous-fired units and 0.9 metric tons from automatric anthracite-
fired units, or about 10% of the total estimated national
emissions of POM per year.
Combustion efficiencies for coal-fired residential heating
equipment were lower than those for larger coal-fired systems
(e.g., utility boilers) as evidenced by the high emission levels
of CO, organic material, and POM compounds. Particulate emissions
and POM emissions were affected by the type of combustion equip-
ment, by coal properties such as coal volatile content and
free swelling index, and by combustion equipment operating
parameters. In contrast to the situation in utility boilers,
coal ash did not have a significant effect on particulate
emissions. Analysis of particulates showed that the composition
is primarily carbon, indicating that particles were not formed
from coal ash but from carbonaceous material volatilized during
combustion.
One measure of the potential environmental effect of coal-fired
residential combustion is the_ratio of the time-averaged maximum
ground level concentrations (xmax) of species emitted from the
source to an ambient air quality level or hazard factor (F).
This ratio is called source severity (S) , i.e., S = Xmax/F* For
criteria emissions, F is the primary ambient air quality standard
(AAQS), while for noncriteria emissions, F is a reduced threshold
limit value (TLV®/300). Values for x^a* are determined using a
Gaussian plume dispersion model and average meteorological
conditions.
An average combustion unit was determined for each coal type as a
basis for severity calculations. All average coal-fired
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combustion devices were automatic units that discharge emissions
to the atmosphere through an exhaust stack or chimney 6.1 m above
ground level. An average bituminous coal-fired unit burns Appala-
chian coal at the rate of 1.1 kg/hr during the heating season
or 5.4 metric tons per year, and it is located in an area with an
average population density of 92 persons/km2. The average anthra-
cite coal-fired unit burns 6.1 metric tons of Pennsylvania
anthracite coal per year at the rate of 1.2 kg/hr during the
heating season and is located in an area with an average popula-
tion density of 132 persons/km2. Lignite-fired combustion units
are located in North Dakota where the average population density
is 4 persons/ km2. The average unit burns 9.9 metric tons/yr of
coal at 1.7 kg/hr during the heating season.
Table 3 gives the severities for the three average sources
considered. Source severities were also determined for emissions
from an array of 100 average houses burning coal. These severi-
ties, presented in Table 4, are approximately 30 times greater
than the single source severities.
Another measure of potential environmental effect is the affected
population, defined as the population around an average source
that is exposed to a specified average ground level concentration
of an emission species. These values are given for each source
in Table 5 as those persons affected by emissions from a single
source and from an array of 100 sources for x/F ^ 1-0 and
X/F Z 0.05. The only emission from a single source found to have
an affected population where x/F > 1.0 was POM. For an array of
100 homes, emissions of particulates, sulfur oxides, nitrogen
oxides, hydrocarbons, and 16 individual elements had affected
populations for x/F >0.05, but only POM had an affected popula-
tion for x/F > 1.0.
Emissions from residential combustion systems are not typically
controlled with add-on equipment; however, proper design and
operation of each unit can decrease emissions. Factors influ-
encing emission levels include such items as fuel properties,
fuel type, firing rate, firing equipment design, cyclic opera-
tion of automatic equipment, and excess air ratio.
Residential combustion of coal for primary heating has shown a
steady decline since the 1940's. Even from 1970 to 1974, coal
combustion for primary heating decreased about 60%. However,
interest in this form of heating has revived since 1974. It is
difficult to predict the impact the current shortage of oil and
natural gas will have on the volume of coal combustion in the
residential sector. Shipments of coal-fired heating equipment
decreased until 1973, when the trend reversed. From 1962 to 1972,
sales decreased by about 60%; but from 1972 to 1975 sales in-
creased by 130% in the area of domestic heating stoves. Primary
heating devices such as stoker furnaces began to shown an increase
in sales in 1976.
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TABLE 3. SOURCE SEVERITIES FOR COAL-FIRED
RESIDENTIAL COMBUSTION EMISSIONS3
Source
Emission species
Particulates
SOX
NOX
Hydrocarbons
CO
Polycyclic organic -materials
Polychlorinated biphenyls
Formaldehyde
Elements:
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Bituminous
3.0
2.0
9.0
2.0
7.0
<4.5
2.0
7.0
7.0
2.0
9.0
5.0
5.0
1.0
7.0
5.0
1.0
5.0
9.0
3.0
1.0
2.0
2.0
2.0
3.0
1.0
3.0
6.0
2.0
2.0
7.0
2.0
4.0
5.0
2.0
8.0
1.0
5.0
7.0
5.0
5.0
3.0
2.0
9.0
4.0
2.0
2.0
5.0
5.0
1.0
5.0
X
X
X
X
X
2.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
io-3
io-2
io-3
io-3
10~5
6
io-7
10-»
lO-3
io-5
IO-3
10-*
IO-3
io-8
io-5
10-*
10-*
io-3
io-3
10-*
10"*
10"*
io-3
10"'°
io-a
10~3
10-8
10"*
10-*
1Q-*
10-8
10-*
10"6
10-*
io-3
10"e
10-*
io-a
IO-5
10-*
10"5
10~°
10"°
10~°
10~7
10-*
10~8
10-*
io-7
ID"5
10-*
10-8
severity
Anthracite
7.
4.
2.
2.
5.
5.
1.
7.
4.
1.
5.
5.
5.
7.
7.
1.
1.
1.
3.
1.
2.
3.
4.
2.
2.
3.
2.
2.
1.
1.
1.
4.
6.
2.
7.
1.
5.
1.
5.
3.
2.
1.
5.
7.
5.
2.
5.
5.
1.
5.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
10-*
io-3
lO-3
io-3
lO-5
10~a
lO-2
10-s
10-*
io-3
io-3
io-8
10"5
io-5
10"*
io-2
io-3
io-3
io-*
10""
io-3
IO-5
10~3
IO-3
lO-5
io-*
io-5
ID"3
IO-5
lO-3
10"6
10-*
lO-3
io-6
10-*
io-a
lO"3
IO-3
10-S
10"°
io-3
io-8
io-7
10-*
10"S
10-*
io-7
lO-3
10-*
10-8
1.
1.
1.
1.
1.
3.
3.
7.
6.
7.
8.
1.
2.
2.
1.
7.
3.
9.
5.
2.
1.
1.
2.
7.
1.
2.
1.
1.
2.
7.
7.
2.
6.
5.
1.
2.
3.
3.
2.
2.
6.
1.
2.
3.
1.
Lignite
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
10-2
10"2
lO-2
io-3
lO-5
lO-3
io-5
10-*
lO-3
10-*
io-5
10-*
io-2
IO-3
io-*
10~s
io-5
10-*
10-"
10~2
ID"3
10"8
10"3
10~5
10-*
io-5
10-*
io-«
io-3
10-*
io-7
10-*
ID"3
ID"3
10~a
10-*
10~8
10~7
10-*
lO-8
lO-8
io-7
10~S
ID"8
10-8
Blanks indicate data not available.
Based on fuel usage of a representative source.
-------
TABLE 4. SOURCE SEVERITIES FOR COAL-FIRED RESIDENTIAL
COMBUSTION EMISSIONS FROM MULTIPLE SOURCES3
Source severity''
Emission species
Participates
SOX
NOX
Hydrocarbons
CO
Polycyclic organic materials
Polychlorinated biphenyls
Formaldehyde
Elements :
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
. Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
.Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel '
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
. Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Bituminous
1.1 x 10-1
5.3 x 10-1
1.9 x 10-1
1.3 x 10-1
2.0 x 10-3
9.1 x 10 1
<2.0 x 10-s
5.0 x 10-*
2.5 x 10~1
2.0 x 10-3
6.0 x lO-3
3.0 x 10-a
1.6 x 10-1
2.0 x 10-«
5.0 x 10-"
2.0 x 10-3
2.0 x 10-3
4.0 x 10~a
1.6 x 10-1
3.0 x 10-a
1.0 x 10-a
4.0 x 10~3
6.0 x 10-a
8.0 x 10-"
6.0 x 10-1
1.2 x 10-1
4.0 x 10-"
1.0 x 10-3
2.0 x 10-a
6.0 x 10~a
7.0 x 10-*
2.0 x 10-a
2.0 x 10~3
1.0 x 10-a
1.8 x 10-1
8.0 x 10-B
3.0 x 10-a
4.2 x 10~1
3.0 x 10-3
3.0 x 10-a
2.0 x 10-3
3.0 x 10-3
1.0 x 10-3
4.0 x 10-a
3.0 x 10-°
1.0 x 10-a
8.0 x 10-"
6.0 x 10-3
8.0 x 10-»
2.0 x 10~3
5.0 x 10-'
2.0 x 10-3
Anthracite
2.0 x 10~a
1.3 x 10-1
5.0 x 10~a
5.0 x lO-3
1.0 x 10~3
1.7
3.4 x 10-1
2.0 x 10-
2.0 x 10-
3.0 x 10-
1.7 x 10-
2.0 x 10-
2.0 x 10-
2.0 x 10-
8.0 x 10~3
2.0 x 10~a
3.7 x 10-1
3.0 x lO-3
1.0 x 10~a
5.0 x 10~3
5.0 x 10-a
9.0 x 10-"
1.5 x 10~1
9.0 x 10-a
6.0 x 10-"
1.0 x 10-3
7.0 x 10-"
7.0 x 10-3
5.0 x 10-"
3.0 x 10-a
1.0 x 10-'3
1.0 x 10-a
2.1 x 10-1
9.0 x 10-o
3.0 x 10-2
4.6 x 10-1
2.5 x 10-1
4.0 x 10-a
2.0 x 10-3
1.0 x 10-3
6.0 x 10~a
3.0 x 10-3
2.0 x 10-8
3.0 x lO-3
2.0 x 10-3
7.0 X 10~3
2.0 x 10-°
2.0 x 10-3
4.0 x lO-3
2.0 x 10-3
Lignite
4.1 x 10-1
5.0 x 10- 1
2.4 x 10~1
3.0 x lO-3
2.0 x 10-"
9.0 x 10-a
1.0 x 10-3
3.0 x 10-a
1.9 x 10-i
2.0 x 10-3
3.0 x 10-3
4.0 x 10-3
5.8 x 10-1
6.0 x lO-2
5.0 x 10~3
2.0 x 10-3
1.0 x 10~3
3.0 x 10-3
2.0 x 10-«
6.3 x 10-1
4.0 x 10-3
5.0 x 10-»
8.0 x 10-3
2.0 x 10-3
5.0 x 10-3
7.0 x 10-"
5.0 x 10~3
1.0 x 10-3
8.0 x 10-3
2.0 x 10-3
2.0 x 10-»
7.0 x 10-3
2.1 x 10-1
2.5 x 10-1
4.4 x 10-1
8.0 x 10-3
5.0 x 10~3
1.0 x 10-°
8.0 x 10~3
9.0 x 10-"
2.0 x 10~3
5.0 x 10-"
7.0 X 10-"
1.0 x 10~3
5.0 x 10-"
Blanks indicate data not available.
Emissions assumed constant over a 24-hr period during the
heating season.
-------
TABLE 5. POPULATION EXPOSED TO EMISSIONS FROM AVERAGE
COAL-FIRED RESIDENTIAL HEATING DEVICES
(Number of persons)
Bituminous
Anthracite
Lignite
Emission species x/F > 0.05 x/F > 1.0 x/F > 0.05 x/F > 1.0 x/F > 0.05 x/F >
Single source:
POM
Multiple sources i
Particulate
SOx
NOx
Hydrocarbons
POM
Elements:
Aluminum
Arsenic
Barium
Beryllium
Calcium
Chlorine
Fluorine
Iron
Lead
Magnesium
Phosphorus
Potassium
Silicon
Silver
Sodium
Thallium
115
585
4,361
1/593
783
>5,000
2,537
98
0
1,174
0
1,174
98
4,930
714
0
0
1,353
3,826
0
0
0
5
0
0
0
0
>5,000
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
0
783
0
0
>5,000
3,326
0
0
1,218
0
3,473
0
1,035
394
0
0
. 1,853
3,852
2,537
0
98
0
0
0
0
0
352
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3,826
>5,000C
2,403
0
0
394
0
1,560
0
4,766
97
0
>5,000C
0
296
296
0
1,853
2,537
4,089
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Only species with affected populations greater than zero are listed.
Not determined.
cActual number could not be determined.
U.S. Bureau of Census data up to 1975 indicate that residential
heating with coal has continued to decline in all parts of the
United States except the West, where 1975 usage showed a 50%
increase over that in 1974. Recent reports from manufacturers
and distributors of this equipment and from local and state
officials show that there is a renewed interest in this type of
heating. At this time, the magnitude of the trend cannot be
predicted.
10
-------
SECTION 3
SOURCE DESCRIPTION
Only 1% of U.S. housing units with primary heating devices burned
coal for primary heating in 1974. Natural gas, the most popular
heating fuel, was used in about 56% of the housing units (1).
Emissions from the small fraction of housing units burning coal
are major contributors to total national emissions from resident-
ial combustion. For example, in 1973, CO emissions from coal-
fired residential combustion were estimated to be 79% of the
total CO emitted from all residential sources (2).
Table 6 gives the breakdown of units heated by different fuel
types (1) .
TABLE 6. HOUSING UNITS HEATED BY A PARTICULAR FUEL
Housing units,
Fuel type 1974 (1)
Utility gas 39,471,000
Bottled, tank, or liquefied
petroleum gas 4,143,000
Fuel oil, kerosene, etc. 16,835,000
Coal or coke 741,000
Wood 658,000
Electricity 8,407,000
Other fuels 90,000
Total 70,345,000
(1) Current Housing Reports; Bureau of the Census Final Report
H-150-74; Annual Housing Survey: 1974, Part A; General
Housing Characteristics for the United States and Regions.
U.S. Department of Commerce, Washington, D.C., August 1976.
179 pp.
(2) Surprenant, N., R. Hall, C. Young, D. Durocher, S. Slater,
T. Susa, and M. Sussman. volume II: Preliminary Emissions
Assessment of Conventional Stationary Combustion Systems.
EPA-600/2-76-046b, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, March 1976. 523 pp.
11
-------
SOURCE DEFINITION
Coal-fired residential combustion sources include all equipment
that burns bituminous, anthracite, or lignite coal to generate
household heat. These devices produce up to 420 MJ/hr of heat in
occupied structures containing one or two housing units.
A negligible amount of coal is also used for cooking. Approxi-
mately 36,000 housing units were reported to use coal as cooking
fuel in 1974 (1). These units amounted to only 5% of the housing
units heating with coal. Considering that cooking utilizes about
10% of the energy needed for heating (3, 4), it follows that coal
burned for cooking purposes is only about 0.5% of the coal burned
in the residential sector for heating.
Also excluded from this source type are coal-fired devices
located in large multiunit structures because they represent only
a small portion of the total coal combustion for residential
heating and are in the commercial/institutional size range. In
1970 approximately 80% of all housing units heated by coal were
located in structures of less than three housing units (5).
EQUIPMENT DESCRIPTION
A wide variety of coal-fired heating equipment is available for
residential usage. In 1970, coal-fired residential heating
devices were distributed as follows: 16% steam or hot water
boilers, 39% warm-air furnaces, and 45% domestic heating stoves
(5). Figures 1, 2, and 3 show typical units on the market
today (6-8).
(3) Patterns of Energy Consumption in the United States. Pre-
pared by Stanford Research Institute for Office of Science
and Technology, Executive Office of the President, Washington,
D.C., January 1972. 221 pp.
(4) Wells, R. M., and W. E. Corbett. Electrical Energy as an
Alternate to Clean Fuels for Stationary Sources: Volume I.
Contract 68-02-1319, Task 13, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, March 1976.
181 pp.
(5) Census of Housing: 1970 Subject Reports; Bureau of the
Census Final Report HC(7)-4; Structural Characteristics of
the Housing Inventory. U.S. Department of Commerce,
Washington, D.C., June 1973. 450 pp.
(6) Giammar, R. D., R. B. Engdahl, and R. E. Barrett. Emissions
from Residential and Small Commercial Stoker- Coal-Fired
Boilers Under Smokeless Operations. EPA-600/7-76-029, U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, September 1976. 77 pp. (continued)
12
-------
ROOM Al R
COMBUSTION
AIR BLOWER
Figure 1. Stoker-fed residential
coal-fired boiler (6).
Figure 2.
Cutaway view of
stoker-fired
residential fur-
nace (7) .
(1) THE REGULATOR - SETS THE DIAL FOR THE DESIRED
TEMPERATURE. A BIMETAL COIL INSIDE THE REG-
ULATOR RAISES A CHAIN CONNECTED TO THE
MAGNETIC DAMPER (2).
(2) THE MAGNETIC DAMPER - AUTOMATICALLY ADMITS AIR
WHEN THE REGULATOR CALLS FOR HEAT. Al R TRAVELS
BELOW THE GRATE (3) AND BEHIND THE LINERS (4).
(3) GRATE - PROTECTED BY 50 - 75.mm LAYER OF ASH AT
ALL TIMES.
(4) LINERS - AIR TRAVELS UPWARD BEHIND THE LINERS AN
AND THEN IS DEFLECTED INTO THE COMBUSTION
CHAMBER BY THE LINER RETAINERS.
(5) LINER RETAINERS
(6) GAS COMBUSTION FLUE - SMOKE IS FORCED DOWNWARD
BACK INTO FIRE BEFORE IT CAN ENTER THE COMBUSTION
FLUE. THE SECONDARY AIR PROVIDES THE OXYGEN
NECESSARY FOR COMPLETE COMBUSTION TO OCCUR.
17) ASH PAN
Figure 3. Hand-fed room heater for burning coal or wood (8)
13
-------
Most boilers and warm-air furnaces are stoker-fed automatic
heating devices controlled by thermostats. Thermostatically
controlled stoves or room heaters are also on the market.
Figure 4 is a schematic of an automatic coal-fired system.
Typical automatic coal-fired systems consist of a fuel storage
facility, fuel feed mechanism, combustion chamber and fan, heat
transfer surface, heat delivery system, temperature controls,
exhaust stack, ash chamber, and, in some cases, automatic ash
removal system. Automatic residential coal-fired heating equip-
ment ranges in size from about 76 MJ/hr to 420 MJ/hr (7, 9, 10, 11)
Because of uncertainties over fuel prices and fuel availability,
some manufacturers are marketing units that have an interchange-
able stoker and gas burner. Other furnaces contain both burner
and stoker; the gas burner is ignited if the coal supply runs
out. Although not stated in the manufacturers' literature, some
coal-fired units can also be fired with wood chips (12).
Residential automatic coal-fired heating equipment is estimated
to be about 55% to 60% efficient (3, 6, 13). This is difficult
to verify, because the cyclic nature of the operation prevents an
accurate determination of energy balances. Steady-state
efficiencies are about 70% (14).
(continued)
(7) Prill's Self Cleaning Coal Furnaces (manufacturer's bro-
chure). Prill Manufacturing Co., Sheridan, Wyoming. 2 pp.
(8) Riteway, the Quality Name in Energy Innovations (manufac-
turer's brochure). Riteway Manufacturing Co., Harrisonburq,
Virginia. 12 pp. *
(9) Weil-McLain 57 and 40 Coal-Fired Boilers (manufacturer's bro-
chure). Weil-McLain Company, Inc., Michigan City,
Indiana. 4 pp.
(10) Automatic Heat in a Single Package - The Combustioneer "77"
Space Heater (manufacturer's brochure). The Will-Burt
Company, Orrville, Ohio. 4 pp.
(11) Automatic Coal Heating with Hardin Automatic Coal Furnaces
(manufacturer's brochure). S&S Manufacturing, Inc., Hardin,
Montana. 2 pp.
(12) Heath, W. G. A Proposal for the Development of a Domestic
Fuel Supply, Delivery, and Management System for the Rocky
Boy's Indian Reservation, Montana. American Indian Develop-
ment Association, Bellingham, Washington, 1976. 43 pp.
(13) Barrett, C. E., S. E. Miller, and D. W. Locklin. Field
Investigation of Emissions from Combustion Equipment for
Space Heating. EPA-R2-73-084a, U.S. Environmental Protec-
tion Agency, Research Triangle Park, North Carolina,
June 1973. 213 pp.
(continued)
14
-------
EXHAUST GAS
TO OUTSIDE
COLD FLUID
RETURN
PUMP OR
FAN
Fua
STORAGE
FEED
MECHANISM
LEGEND
TC - TEMPERATURE
CONTROLLER
•ih aECTRICAL
WIRING
FUEL
HEATED FLUID TO
HOUSING UNIT
HEAT TRANSFER
COMBUSTION
CHAMBER
-COMBUSTION AIR
ASH
•ih
-Ih
Figure 4. Schematic of automatic coal-fired residential
heating system for boiler or air furnace.
A problem with coal-fired residential combustion equipment is
that only a limited range of different coal types can be
efficiently burned in any particular unit. Coal-fired heating
units are originally designed to burn a specific type of coal
most efficiently, usually based upon the type of coal available
in a certain region. Consequently, units designed to burn
anthracite coal do not operate efficiently when fired with other
coals such as bituminous. Even units designed to burn bituminous
coal will not burn all bituminous coal effectively (6, 15, 16).
The various types of combustion equipment and their operation are
covered more specifically in the following sections.
(continued)
(14) Wells, R. M., and W. E. Corbett. Electrical Energy as an
Alternate to Clean Fuels for Stationary Sources: Volume II
Appendix. Contract 68-02-1319, Task 13, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
March 1976. 527 pp.
(15) DeAngelis, D. G., and R. B. Reznik. Source Assessment:
Coal-Fired Residential Combustion Equipment Field Tests,
June 1977. EPA-600/2-78-004o, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, June 1978.
94 pp.
(continued)
15
-------
Boilers
Residential coal-fired boilers, for the most part, produce hot
water rather than steam. These units are best suited for burning
eastern coals because their basic design was developed when the
only major market was in the East. Coal-fired boilers available
today are usually automatic and stoker fed (Figure 1).
Typical designs for bituminous coal-fired units do not have
separate facilities for ash removal. The arrangement is such
that, as fresh fuel is fed to the combustion chamber, combustion
residue, or ash, accumulates at the outer edges of the fuel bed
and must be shoveled out by hand. Frequency of ash removal
depends on the nature of the coal and may average once a day.
Combustion of high volatile caking coals can result in large
fused rings of combustion residue called clinkers.
Anthracite coal can be burned in a stoker-fed boiler when it is
coupled with the proper stoker. Currently one manufacturer has
a stoker available that effectively burns anthracite, and
possibly other smokeless coals, and is equipped with an ash pit
located below the combustion chamber (6). One manufacturer of
automatic anthracite coal combustion equipment for residential
heating has a unique design in which the fuel feed and combustion
equipment are an integral part of the boiler. This unit employs
the overfeed arrangement for feeding and burning coal (discussed
later in Section 3 under "Combustion Process") but differs some-
what in combustion air flow. It is equipped with a cyclone
for greater heat transfer and for fly ash removal from hot flue
gases. Combustion is by induced draft rather than by forced
draft as in conventional stoker systems (17).
Warm-Air Furnaces
Coal-fired residential warm-air furnaces have entered the market
more recently than boilers and are increasing in popularity
because of their modern design and adaptability to present house-
hold heat distribution systems (Figure 2). Present designs are
limited to combustion of lignite and western subbituminous coal
(18), although several manufacturers are exploring design
modifications to burn a wider variety of coals.
(continued)
(16) A Survey of Coal-Fired Heating Equipment Manufacturers.
Prepared by Mineral Economics Institute,.Colorado School of
Mines, for U.S. Department of the Interior, Bureau of Mines,
March 4, 1977. 13 pp.
(17) The Completely New Way to Heat with Anthracite (manufac-
turer's brochure). Axeman-Anderson Company, Williamsport
Pennsylvania. 6 pp.
16
-------
Automatic coal-fired warm-air furnaces are fed by stokers similar
in design to those used for coal-fired boilers. Several of these
stokers have a rotating ring at the outer edges of the fuel bed
to break up clinkers and force ash from the fuel bed area into a
removable ash pan. These units are finding increasing demand in
the West where most manufacturers are located.
Other Types of Coal-Fired Equipment
Besides the automatic coal-fired units just described, various
other, less sophisticated devices can be used for residential
combustion of coal. Such devices are used mostly for auxiliary
heating but also for primary heating of small dwellings. Many
of these units were originally designed to fire wood or wood and
coal. These devices include room heaters (Figure 3), metal
stoves, and metal and masonry fireplaces. Some devices can be
thermostatically controlled, but most are hand fed and use com-
bustion air induced by natural draft. Combustion efficiency is
often controlled by a hand-operated damper in the exhaust stack
or by adjustable openings in the doors of units that have them.
Combustion efficiencies of these units vary widely and can be
much lower than those for automatic units.
Automatic Stokers
A stoker is a mechanical device that feeds solid fuel to a com-
bustion operation. Stokers employed for residential combustion
are of the underfeed type; in addition to feeding the coal, they
also provide supporting mechanisms for combustion such as the
retort, wind box, and combustion air supply. Figure 5 (19)
illustrates a typical stoker assembly.
During stoker operation a worm-feed mechanism conveys coal from a
hopper to the fuel bed inside the furnace or boiler. A multiple
grooved pulley on the motor controls the coal feed rate. Under-
feed stokers deliver fresh coal to the fuel bed by feeding it
underneath the hot coals. Below the fuel bed coal is devolatized
and ignited in a cast iron chamber, or retort. The retort is
surrounded by a wind box that delivers combustion air to the fuel
bed through slotted holes called tuyeres. The tuyeres are part
of a cast iron ring which in some units is rotated by the feed
screw to break up clinkers and push ash to the outside of the
fuel bed. Air for combustion is supplied by a blower located
under the coal hopper and driven by the coal feed motor. Air
flow can be controlled by a cover on the fan housing or by a
(18) Personal communication with John O'Brien, Solid Fuel Systems,
Inc., Englewood, Colorado, 17 December 1976.
(19) Domestic Stokers, Hopper and Bin Feed by Will-Burt (manufac-
pp?™ W346-?5-2M' The Will-Burt Company,
17
-------
TOP VIEW
* 1
Lxx-mi i
/
i
SIDE VIEW
1. HOPPER
2. ELECTRIC MOTOR
3. TRANSMISSION
4. COAL FEED TUBE
5. FEED WORM
6. RETORT
7. RETORT AIR CHAMBER
8. COMBUSTION CHAMBER
9. WIND BOX AND TUYERES
Figure 5. Will-Burt stoker assembly (19).
counterweight damper located in the air delivery tube. The motor
driving the feed screw and the blower is controlled by a room
thermostat, a limit switch, and a holdfire timing relay.
Operation of automatic stoker-fed coal-fired
the need for daily coal handling and manual
delivery. After a batch of coal is received
coal feed rate is adjusted to match the coal
the heating requirements. At the same time,
level is adjusted to provide adequate excess
optimum combustion. The thermostat is then
temperature, and the only routine tasks left
coal hopper and removing ash.
equipment eliminates
adjustment of heat
from a dealer, the
1 s heating value with
the combustion air
air to insure
set to the desired
are charging the
Stoker hoppers can hold up to a 2-week supply of coal, depending
on the heating demand and fuel heating value. Bin-fed stokers
.are available as an alternative that eliminates the need to fill
the hopper by hand. In this system, coal is fed directly from
the storage bin to the burner. Depending on the type of coal
burned and the heat demand, ashes need only be removed for
disposal once every week to once every 4 weeks. In some cases
ashes fall into a slide-out pan for easy removal.
18
-------
Automatic Equipment Heating Cycle
Characteristic of automatic residential heating units is the
thermostatically controlled heating cycle (ON/OFF cycle) some-
times referred to as the use-burning cycle. When the thermostat
senses a drop in temperature, i.e./ a demand for heat, the unit
turns on and fuel is fed to the burner. When demand for heat is
satisfied the unit turns off and the flow of fuel ceases.
Coal-fired residential heating units differ somewhat from gas-
and oil-fired units in that air must be provided by a fan to
maintain combustion in the fuel bed. Another difference is that
residual coal continues to burn during the OFF segment even
though no fuel is fed and the combustion fan is off. Combustion
during the OFF segment of a heating cycle is at a much slower
rate than during the ON segment because combustion is maintained
only by natural draft from air leaks in the unit or draft vents
in the combustion chamber door. The ON and OFF segments are
sometimes referred to as high-fired and low-fire conditions,
respectively.
The combustion cycle is a significant factor influencing emission
rates from coal-fired residential combustion units. Emission
data from similar units show significant differences in emission
rates during the ON and OFF segments for the same emission
species (6).
The ratio of heating unit ON/OFF time varies with the heating
season. Thus the coldest months require a longer ON period while
the warmer months require a longer OFF period. For coal-fired
residential heating units this ratio is estimated to be 1:2
during the average portion of the heating season in moderate
climates (see Appendix A). This corresponds to a total of 20 min
of forced combustion out of every hour.
Two extremes occur during a heating season: full load and no
load. During full load operation, the stoker runs continuously
25 minutes of every 30 minutes; a 5-minute "reset" period allows
the fuel bed to cool and the ash to fuse. If the stoker is not
stopped periodically, the ash will agglomerate, forming large
clinkers which cause irregular burning. During no load operation,
the stoker operates for about 5 minutes out of every 30 minutes
to keep the fuel bed alive for quick response when the load
increases.
Barometic Damper
Most automatic coal-fired combustion systems rely on a barometric
damper to control draft through the fuel bed. Barometric dampers
allow room air to enter the exhaust stack when the stack is
placed under negative pressure due to atmospheric conditions.
This is beneficial during the portion of a heating cycle when
19
-------
the stoker and fan are off and the fuel bed remains hot. An
externally induced draft would cause more rapid combustion of
residual coal during the OFF segment and could result in the
fire burning out.
FUEL CHARACTERISTICS
Fuel types consumed by the residential combustion sources studied
in this assessment are anthracite coal, bituminous coal/ and
lignite. The properties and composition of coal are important
factors in its residential combustion. The following properties
are important from an emission and operational standpoint.
Volatile Content
Coals with high volatile content have the potential for emitting
high levels of particulates, hydrocarbons, and polycyclic organic
materials (POM's), especially during the OFF segment of an auto-
matic heating cycle (6, 15). Inefficient combustion of volatile
matter is the cause for the associated high levels of emissions.
A properly designed system may reduce emissions from the combus-
tion of high volatile coals. Volatile matter in coal ranges from
14% to 47% for bituminous coal, 3% to 11% for anthracite coal,
and 12% to 45% for lignite (20).
Free Swelling Index
The free swelling index of coal is a measure of its caking prop-
erties. Coals with a high free swelling index have a greater
tendency to cake, or agglomerate, when burned. This can cause
the fuel bed to degrade and form large fissures over a period of
time, thus preventing the even distribution of air through the
bed. Therefore, emissions associated with incomplete combustion
are a potential problem when burning caking coals. Reducing the
size of coal particles can reduce the caking properties of coals
with high free-swelling index (6, 21). The free-swelling index
for coals ranges from 0 to 9.0 for bituminous coal and is <1.0
for anthracite coal and lignite (21).
(20) Swanson, V. E., J. H. Medlin, J. R. Hatch, S. L. Coleman,
G. H. Wood, S. D. Woodruff, and R. T. Hildebrand. Collec-
tion, Chemical Analysis, and Evaluation of Coal Samples in
1975. Open-File Report 76-468, U.S. Department of the
Interior, Denver, Colorado, 1976. 503 pp.
(21) Given, P. H. Some Comments on the Agglomerating Tendency of
Coal. In: Proceedings of the Coal Agglomerization and Con-
version Symposium (Morgantown, West Virginia, 5-6 May 1975),
J. Smith, compiler. West Virginia University, Morgantown,
West Virginia, April 1976.
20
-------
Coal Size
Coal fines (less than 6.4 mm in diameter) are unavoidable due to
crushing,.screening, and feeding of coal. Excessive fines can
interfere with uniform air distribution in the combustion process.
They can also be entrained in combustion air and carried out in
the flue gas (6). Historically, coal obtained for residential
combustion has been of low quality from a size and contamination
standpoint (22).
Ash Content
In residential combustion equipment, the amount of ash present is
not as important as the ash properties. Coals with low ash-
fusion temperatures may form clinkers that interfere with uniform
feeding of coal and distribution of air. Ash content of coal
typically ranges from 2% to 45% for bituminous coal, 5% to 45%
for anthracite coal, and 3% to 41% for lignite (20) and is most
significant in the amount of solid waste (combustion residue)
generated.
Sulfur Content
The sulfur content of coal determines the level of SOX emissions
during combustion. However, in some western coals the high lime
content in the ash reacts with some of the sulfur and reduces
sulfur oxide emissions (6, 15, 23).
Nitrogen Content
Fuel nitrogen is known to contribute to NOX emissions, but the
level of conversion to NOX is dependent on combustion conditions.
High excess air increases NOX formation, while lower temperatures
decrease the amount formed (24).
Heat and Moisture Content
Both heating value and moisture content determine the coal feed
rate. A coal such as lignite with low heating value requires a
(22) Personal communication with Stratton Schaeffer, Consulting
Engineer, Camp Hill, Pennsylvania, 11 October 1977.
(23) Ctvrtnicek, T. E., S. J. Rusek, and C. W. Sandy. Evaluation
of Low-Sulfur Western Coal: Characteristics, Utilization,
and Combustion Experience. EPA-650/2-75-046, U.S. Environ-
mental Protection Agency, Research Triangle Park, North
Carolina, May 1975. 555 pp.
(24) Mitchell, R. E. Nitrogen Oxide Formation from Chemically-
Bound Nitrogen During the Combustion of Fossil Fuels.
SAND76-8227, Sandia Laboratories, Livermore, California,
June 1976. 25 pp.
21
-------
higher feed rate to meet the heating demand. So does a coal with
a high moisture content, which acts as a diluent, reducing flame
temperature and increasing sensible heat carried out by waste
flue gases.
Heating values for coals range from 16 MJ/kg to 35 MJ/kg for
bituminous and anthracite coals and 4.6 MJ/kg to 23 MJ/kg for
lignite. Moisture contents range from 0.7% to 35% for bituminous
coal, 0.5% to 4.0% for anthracite coal, and 23% to 53% for
lignite (20).
Elemental Content
Coal has been shown to contain at least 74 elements in addition
to carbon, hydrogen, and nitrogen (25). All of these elements
are potential emissions when the coal is burned, either as part
of the fly ash or in a volatilized form. Concentrations of
these elements in coal can vary significantly from state to state,
mine to mine, and even within the thickness of a coal seam. The
concentration of a particular element in coal can range over two
orders of magnitude (20, 25).
Tables 7 and 8 list average compositions and properties of U.S.
coals burned in the residential sector (20, 21).
TABLE 7. AVERAGE COMPOSITION OF COAL, HEATING VALUE,
AND FREE SWELLING INDEX (20, 21)
Property
Composition, percent:
Moisture
Volatile matter
Fixed carbon
Ash
Hydrogen
Carbon
Nitrogen
Oxygen
Sulfur
Sulfate sulfur
Pyritic sulfur
Organic sulfur
Heating value:
MJ/kg
(Btu/lb)
Free swelling index
All coal
(488 samples)
10.0
29.9
48.8
11.3
5.1
64.1
1.1
16.4
2.0
0.12
1.19
0.70
26.0
(11,180)
0 to 9.0
Anthracite
(38 samples)
1.4
6.5
79.5
12.6
2.4
80.1
• 0.8
3.2
0.8
0.02
0.35
0.48
29.7
(12,780)
0 to 0.5
Bituminous
(277 samples)
4.8
32.3
51.2
11.7
5.0
69.1
1.3
10.3
2.7
0.16
1.70
0.88
28.5
(12,260)
3.0 to 9.0
Subbituminous
(205 samples)
18.4
33.8
39.0
8.8
5.9
54.3
1.0
29.3
0.7
0.04
0.35
0.32
21.9
(9,410)
0.5 to 3.0
Lignite
(28 samples)
41.5
23.0
20.9
14.6
6.8
29.9
0.5
46.5
1.7
0.24
0.68
0.75
11.6
(5,000)
0
(25) Kessler, T., A. G. Sharkey, Jr., and R. A. Friedel. Analysis
of Trace Elements in Coal by Spark-Source Mass Spectrometry.
Report of Investigations 7714, U.S. Department of the
Interior, Pittsburgh, Pennsylvania, 1973. 8 pp.
22
-------
TABLE 8. AVERAGE CONCENTRATION OF 36 ELEMENTS
IN COAL (20)a
Units
All coal
(799 samples)
Anthracite
(53 samples)
Bituminous
(509 samples)
Subbituminous
(183 samples)
aWhole-coal basis.
parts per million by weight.
Lignite
(54 samples)
Silicon
Aluminum
Calcium
Magnesium
Sodium
Potassium
Iron
Manganese
Titanium
Arsenic
Cadmium
Copper
Fluorine
Mercury
Lithium
Lead
Antimony
Selenium
Thallium
Uranium
Zinc
Boron
Barium
Beryllium
Cobalt
Chromium
Gallium
Molybdenum
Niobium
Nickel
Scandium
Strontium
Vanadium
Yttrium
Ytterbium
Zirconium
%
%
%
%
%
%
%
%
%
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
Ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
2.6
1.4
0.54
0.12
0.06
0.18
1.6
0.01
0.08
15
1.3
19
74
0.18
20
16
1.1
4.1
4.7
1.8
39
50
150
2
7
IS
7
3
3
15
3
100
20
10
1
30
2.7
2.0
0.07
0.06
0.05
0.24
0.44
0.002
0.15
6
0.3
27
61
0.15
33
10
0.9 •
3.5
5.4
1.5
16
10
100
1.5
7
20
7
2
3 •
20
5
100
20
10
1
50
2.6
1.4
0.33
0.08
0.04
0.21
2.2
0.01
0.08
25
1.6
22
77
0.20
23
22
1.4
4.6
5.0
1.9
53
50
100
2
7
15
7
3
3
20
3
100
20
10
1
30
2.0
1.0
0.78
0.18
0.10
0.06
0.52
0.006
0.05
3
0.2
10
63
0.12
7
5
0.7
1.3
3.3
1.3
19
70
300
0.7
2
7
3
1.5
5
5
2
100
15
5
0.5
20
4.9
1.6
1.2
0.31
0.21
0.20
2.0
0.015
0.12
6
1.0
20
94
0.16
19
14
0.7
5.3
6.3
2.5
30
100
300
2
5
20
7
2
5
15
5
300
30
15
1.5
50
AVERAGE SOURCE DEFINITION
To help evaluate the potential environmental effects of coal-
fired residential combustion, it is useful to define typical or
average combustion units. In this assessment, three separate
average sources were defined; one each for residential heating
units burning bituminous coal, anthracite coal, and lignite.
Average sources are defined in terms of fuel characteristics,
firing rate, emission height, and average population density
around the source. The methodology employed to define the
average source types is described in Appendix A.
Bituminous Coal-Fired Equipment
An average bituminous coal-fired residential combustion source is
estimated to burn 1.1 kg/hr of coal during the heating season or
5.4 metric tons/yr in an automatically operated unit. It has a
chimney discharging emissions to the atmosphere 6.1 m above
ground level, and it is located in an area having an average popu-
lation density of 92 persons/km2.
23
-------
The bituminous coal burned in the typical source originates in
the Appalachian coal region. This is based on the fact that
approximately 72% of all bituminous coal shipped to retailers in
1974 came from that region (26). The average analysis of
Appalachian bituminous coal is presented in Table 9 (20, 27, 28).
Anthracite Coal-Fired Equipment
An average anthracite coal-firing residential combustion system
is estimated to consume 1.2 kg/hr of coal during the heating
season or 6.1 metric tons/yr. It has a chimney 6.1 m above
ground level. The typical unit is located in an area with a
population density of 132 persons/km2. The anthracite coal
burned in the representative source comes from eastern Pennsyl-
vania and has an average analysis as shown in Table 10.
Lignite Coal-Fired Equipment
An average lignite coal-fired residential combustion source is
located in North Dakota and is estimated to burn 1.7 kg/hr during
the heating season or 9.9 metric tons/yr. It has a chimney
height of 6.1 m and is located in an area having a population
density of 4 persons/km2. The coal burned in this source is
North Dakota lignite and has the average analysis given in
Table 11.
(26) Mineral Industry Surveys, Bituminous Coal and Lignite Dis-
tribution, Calendar Year 1974. U.S. Department of the
Interior, Washington, D.C., April 18, 1975. 74 pp.
(27) Ruch, R. R., H. J. Gluskoter, and N. F. Shimp. Occurrence
and Distribution of Potentially Volatile Trace Elements in
Coal. EPA-650/2-74-054, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, July 1974.
96 pp.
(28) Magee, E. M., H. J. Hall, and G. M. Varga, Jr. Potential
Pollutants in Fossil Fuels. EPA-R2-73-249 (PB 225 039),
U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, June 1973. 223 pp.
24
-------
TABLE 9. ARITHMETIC MEAN OF PROXIMATE AND ULTIMATE
ANALYSES AND ELEMENTAL COMPOSITION FOR
APPALACHIAN COAL REGION SAMPLES
Constituent
Moisture, %
Volatile matter, %
Fixed carbon, %
Ash, %
Hydrogen , %
Carbon , %
Nitrogen, %
Oxygen , %
Sulfur, %
Heating value, MJ/kg
Elements , g/kg :
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Arithmetic
mean
2.8
31.6
54.6
11.0
4.9
72.6
1.3
7.8
2.3
30
16
0.0012
0.027
0.100
0.002
0.0001
0..030
o.oii
0,0007
1.2
0.72
0.020
0.007
0.024
0.080
0.007
19
0.0153
0.0276
0.68
0.62
0.00024
0.003
0.015
0.005
0.09
2.3
0.005
0.0047
27
0.00003
0.32
0.1
0.00034
0.0001
0.0048
0.0024
0.9
0.0014
0.020
0.001
0.010
0.020
0.050
Number of
samples
158
158
158
158
158
158
158
158
158
158
331
331
331
331
331
10
331
19
331
331
19
331
331
331
331
331
331
331
331
331
331
331
331
331
331
14
331
331
• 331
331
10
331
331
10
10
331
95
331
331
331
331
331
331
331
Reference
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
27
20
20,27
20
20
20,27
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20,27
20
20
20
20
27
20
20
27
27
20
20,27,28
20
20
20
20
20
20
20
25
-------
TABLE 10. ARITHMETIC MEAN OF PROXIMATE AND ULTIMATE
ANALYSES AND ELEMENTAL COMPOSITION FOR
PENNSYLVANIA ANTHRACITE REGION SAMPLES
Constituent
Moisture, %
Volatile matter, %
Fixed carbon, %
Ash, %
Hydrogen , %
Carbon , %
Nitrogen, %
Oxygen , %
Sulfur, %
Heating value, MJ/kg
Elements, g/kg:
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Arithmetic
mean
1.4
6.5
79.5
12.6
2.4
80.1
0.8
3.2
0.8
29. '7
20
0.0009
0.006
0.1
0.002
<0.0001
0.01
0.001
0.0003
0.7
1.5
0.02
0.007
0.027
0.061
0.007
4.4
0.01
0.033
0.6
0.02
0.0002
0.002
0.02
0.003
0.075
2.4
0.005
0.004
27
0.003
0.5
0.1
<0.0001
0.05
0.003
0.001
1.5
0.002
0.02
0.001
0.01
0.016
0.05
Number of
samples
38
38
38
38
38
38
38
38
38
38
1
53
53
53
53
1
53
1
53
53
1
53
53
53
53
53
53
53
53
53
53
53
53
53
53
1
53
53
53
53
1
53
53
1
53
1
1
53
53
53
53
53
53
53
Reference
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
25
20
25
20
20
25
20
20
20
20
20
20
20
20
20
20
20
20
20
20
25
20
20
20
20
25
20
20
25
20
25
25
20
20
20
20
20
20
20
26
-------
TABLE 11. ARITHMETIC MEAN OF PROXIMATE AND ULTIMATE
ANALYSES AND ELEMENTAL COMPOSITION FOR
NORTH DAKOTA LIGNITE COAL SAMPLES
Constituent
Moisture , %
Volatile matter, %
Fixed carbon, %
Ash, %
Hydrogen , %
Carbon , %
Nitrogen, %
Oxygen , %
Sulfur, %
Heating value, MJ/kg
Elements, g/kg:
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Arithmetic
mean
29.7
29.6
32.1
8.6
6.1
43.1
0.7
40.0
1.5
16.7
3.7
0.0003
0.0067
0.4
0..0002
0.12
0.0001
12
0.17
0.002
0.001
0.0052
0.026.
0.0014
13
0.0034
0.0021
3.43
0.048
0.002
0.0022
0.32
0.2
0.0012
0.0008
8.5
0.002
3.57
0.34
0.0035
0.0004
0.33
0.0007
0.004
0.0002
0.003
0.0033
0.01
Number of
samples
7
7
7
7
7
7
7
7
7
7
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
16
18
18
2
18
18
18
5
18
18
18
13
18
18
18
Reference
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
*• V
20
20
*• V
20
*• \J
20
20
ft \J
20
28
** W
20
20
20
20
20
20
20
27
-------
COMBUSTION PROCESS
General Description
Because of the varied nature of coal, a precise quantification of
combustion chemistry is difficult to determine. The oxidation of
hydrocarbons to carbon dioxide and water is only part of the
reaction chemistry. Coals contain a variety of chemical constit-
uents that may participate to some extent in reactions at high
temperatures. Mineral substances such as silicates, sulfides,
and halogen salts oxidize in the flame during combustion to form
ash that is either retained in the fuel bed or entrained in the
flue gas. Oxides of certain metals such as mercury and selenium
have high vapor pressures and are thus partially volatilized
during combustion. These vapors later condense in the postflame
region and appear as ash, particulate emissions, or colloidal
suspension in the flue gas.
The processes involved in the combustion of coal are illustrated
in Figure 6 (29). Solid fuels burn in diffusion flames because
the solid phase cannot be mixed with oxidants on a molecular
scale. With the addition of radiant energy from an ignition
device or the combustion zone, volatile components are vaporized
and flow away from the solid surface while the solid portion of
the fuel begins to pyrolyze. At this point, no oxidation of the
fuel at the surface occurs due to lack of intimate contact with
the oxidant. A diffusion flame is established where the mixing
of combustibles and oxidant forms a combustible mixture. This is
noted as the primary combustion zone. Additional transfer of
heat results in additional vaporization of volatiles, pyrolysis,
and a rise in surface temperature of the solid. After the deple-
tion of volatiles, oxidation of the solid materials commences.
Oxygen diffuses to the solid surface where oxidation of the non-
volatiles occurs, resulting in the release of more heat. Carbon
monoxide and dioxide, water, hydrogen, nitrogen oxides, sulfur
oxides, carbonaceous particulates from noncombusted vapors, and
metallic oxides from noncombustible constituents may form or
begin to form in the combustion zone.
The postflame region is that region directly downstream of the
combustion zone. Many chemical and physical processes may occur
in the postflame region because the reactants may be both gaseous
and solid. Radical recombination reactions such as the recombi-
nation of atomic oxygen and the formation of water from atomic
hydrogen and the hydroxyl radical occur as the combustion gases
cool. Carbon dioxide and atomic hydrogen are formed by the com-
bination of carbon monoxide and the hydroxyl radical. Pyrolytic
Edwards, J. B. combustion, Formation, and Emission of Trace
Species. Ann Arbor Science, Ann Arbor, Michigan, 1974.
240 pp.
(29)
240 pp
28
-------
PYROLYSIS
OXIDATION
ONDENSED PHASE
REACTION ZONE
RECEDING INTERFACES
Figure 6. Combustion of a solid (29).
Combustion Geometry
Underfeed Arrangement —
unburned combustibles to leave the bed Blow
can
29
-------
SECONDARY AIR
(OVERFIRE)
ASH ENTRAPMENT
SECONDARY
OXIDATION ZONE
C + 02— COj
ASHLAYFR
REDUCTION ZONE
COZ*C — 2CO
OXIDATION ZONE
C + 0 — COj
IGNITION PLANE
PREHEAT ZONE
PRIMARY AIR
(UNDERFIREI
FUEL
< UNDERFEED I
COMPOSITION
& TEMPERATURE
Figure 7. Underfeed arrangement of a solid fuel bed (29).
Combustion Formation and Emission of Trace Species, Copyright © 1974.
Reprinted with permission of Ann Arbor Science Publishers, Inc.
also form in a caked bed; the resulting areas of high velocity
gases entrain particulate matter.
Overfeed Arrangement--
Combustion of coal in fireplaces, stoves, or in any hand-fed
system is represented by the overfeed arrangement of a fuel bed
as illustrated in Figure 8. Some automatic combustion equipment
also utilizes this arrangement.
SECONDARY AIR
(OVERFIRE)
GRATE
PRIMARY AIR
(UNDERFIRE
EFFLUENT
FUEL
OVERFEED )
SECONDARY
OXIDATION ZONE
2 CO +0, — 2 CO,
PREHEAT ZONE
IGNITION PLANE-
REDUCTION ZONE
CO, + C — 2 CO
"
OXIDATION" ZONE
_ C * 0, — CO,
ASH LAYER
COMPOSITION
8, TEMPERATURE
Figure 8, Overfeed arrangement of a solid fuel bed (29).
Combustion Formation and Emission of Trace Species, Copyright © 1974.
Reprinted with permission of Ann Arbor Science Publishers, Inc.
The air supply in the overfeed arrangement is divided between
primary air fed under the bed (or grate) and secondary air
introduced above the fuel bed. Primary air controls the rate of
combustion because the coal cannot be consumed at a rate greater
30
-------
than the available oxygen permits. A deficiency or excess of
primary air will reduce the bed temperature and the rate of
combustion. Excess air levels as high as 7,000% have been
measured for combustion of coal in fireplaces (30). Secondary
air controls the overall combustion efficiency by oxidizing any
unburned or partially oxidized combustible materials emitted
from the fuel bed.
Overfeed firing has a major problem: as fresh fuel is supplied
to 'the top of the bed, it is preheated with hot combustion gases,
and its volatile components are driven off. Since little or no
oxygen is present in this region, these volatile organics can
only undergo pyrolytic reactions. Therefore, secondary air must
be supplied for oxidation to take place above the fuel bed.
However, excess secondary air can quench the reactions and
produce partial oxidation products. Usually 30% to 50% total
excess air is sufficient to compensate for incomplete mixing and
allow complete combustion.
Hand-feeding of coal to a stable fuel bed results in the upset of
a number of combustion process steps. At this stage of combus-
tion, the flue gas contains the greatest load of combustible spe-
cies, and the overall combustion process is least efficient (29).
GEOGRAPHICAL DISTRIBUTION
Coal-fired residential heating units are used throughout the
United States and are concentrated near major coal regions. This
distribution pattern reflects the desire of homeowners to burn
fuel that is readily available and inexpensive.
The number of residential housing units heated with coal is com-
piled by the U.S. Bureau of Census, but the figure does not
include homes using coal for auxiliary heat. In addition, some
housing units are in multiunit structures having one common heat
source. Thus the reported number of housing units heated by coal
is not identical to the number of coal-fired heating devices. In
this assessment, two reports from the 1970 Census of Housing (5,
31) were used in conjunction with the 1974 Annual Housing Survey
(1) to estimate the actual population of coal-fired heating
devices used in homes. (Details .are presented in Appendix B.)
(30) Snowden, W. D., D. A. Alguard, G. A. Swanson, and
W. E. Stolberg. Source Sampling Residential Fireplaces for
Emission Factor Development. EPA-450/3-76-010, U.S. Environ-
mental Protection Agency, Research Triangle Park, North
Carolina, November 1975. 173 pp.
(31) Census of Housing: 1970, Volume 1, Housing Characteristics
for States, Cities, and Counties; Part 1: United States
Summary. U.S. Department of Commerce, Washington, D.C.,
December 1972. 512 pp.
31
-------
Coal consumption by the residential sector in 1974 was determined
by using state fuel consumption data for 1972 (32, 33) in con-
junction with information from the 1970 Census of Housing (5,
31). {Methodology is described in Appendix B.) The procedure
for determining the 1972 fuel usage has been explained in the
literature (32, 34, 35). There is no information available on
the actual population of coal-fired combustion equipment used for
auxiliary heating. It is estimated that the volume of coal
burned for this purpose is insignificant when compared to the
total coal consumed by the residential sector.
State-by-state data on coal heating equipment (i.e., number of
units) and fuel usage appear in Tables 12 and 13, respectively.
Kentucky and Tennessee account for 29% of the approximately
340,000 bituminous coal-fired devices. Alabama, Pennsylvania,
Illinois, Ohio, North Carolina, Virginia, and West Virginia make
up an additional 53% of the population. These nine states con-
sume 83% of the bituminous coal burned in the residential sector.
There are approximately 160,000 anthracite-fired residential
combustion units located in 16 states. Because anthracite coal
is mined in Pennsylvania, these states are either located close
to Pennsylvania or cannot readily obtain bituminous coal (e.g.,
the New England states). Pennsylvania contains 64% of the U.S.
anthracite-fired residential furnaces while New York has 18%.
Residential combustion of lignite is assumed to be limited to the
state of North Dakota. Most lignite is mined in Texas and North
Dakota; however, Texas lignite is not sold to the residential
sector on a commercial scale (36). Lignite is the only coal
(32) 1973 NEDS Fuel Use Report. EPA 450/2-76-004 (PB 253 908),
U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, April 1976. 124 pp.
(33) Personal communication with C. Mann, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
11 November 1976.
(34) Guide for Compiling a Comprehensive Emission Inventory
(Revised). Publication APTD-1135, U.S. Environmental Pro-
tection Agency, Research Triangle Park, North Carolina,
March 1973. 204 pp.
(35) Myers, J. P., and F. Benesh. Methodology for Countywide
Estimation of Coal, Gas, and Organic Solvent Consumption.
EPA-450/3-75-086, U.S. Environmental Protection Agency,
Research Triangle Park/ North Carolina, December 1975.
152 pp.
(36) Personal communication with D. Taylor, Texas Utility
Generating Company, Dallas, Texas, 24 January 1977.
32
-------
TABLE 12. ESTIMATED POPULATION OF COAL-FIRED PRIMARY
RESIDENTIAL HEATING DEVICES, 1974
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Dist. Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Total
Number of primary
residential heatina devices3
Bituminous Anthracite
19,754
755
89
941
277
3,321
0
0
3,230
177
9,121
33
4,956
27,995
4,624
1,377
168
49,734
21
0
0
558
4,625
1,727
1,940
1,362
1,090
264
170
0
0
240
346
17,644
0
9,616
159
594
39,368
0
8,568
299
46,404
130
4,326
0
34,156
2,899
29,001
3,128
848
336,035
0
0
0
0
0
0
752
625
447
0
0
0
0
557
1,129
0
0
0
0
770
7,879
1,915
1,587
0
0
0
0
0
0
447
9,895
0
27,513
0
0
1,041
0
0
100,534
132
. 0
0
0
0
0
744
0
0
0
0
0
155,987
Lignite
0
0
0
0
0
0
0
0
0
0
0
0
0
0
9
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
996
0
0
0
0
0
o
0
0
0
0
o
0
0
o
0
0
996
Located in structures of 1 or 2 housing units;
derived from References 1 and 5 as in Appendix B.
33
-------
TABLE 13. ESTIMATED DISTRIBUTION OF COAL USED
FOR RESIDENTIAL COMBUSTION, 1974
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Dist. Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Total
a
Fuel usage, a metric
Bituminous
61,264
6,222
363
4,461
1,667
21,782
0
0
16,221
176
8,118
15
23,125
216,670
28,547
10,322
869
242,317
66
0
0
4,278
22,448
26,050
5,453
7,021
8,785
1,897
1,112
0
0
1,207
1,663
69,434
0
60,185
758
2,772
216,528
0
25,932
4,405
220,007
365
29,427
0
166,946
10,945
185,318
21,332
7,683
1,744,156
Anthracite
0
0
0
0
0
0
5,644
3,690
2,195
0
0
0
0
4,462
6,972
0
0
0
0
1,783
48,285
14,693
7,701
0
0
0
0
0
0.
942
63,140
0
132,246
0
0
6,517
0
0
552,942
932
0
o
o
o
0
2,057
o
0
0
0
0
854,201
tons/yr
Lignite
0
0
0
0
0
0
0
0
0
0
o
o
o
o
0
0
o
o
o
o
0
o
0
o
o
0
o
0
o
0
o
0
o
0
18,784
o
o
o
o
o
o
\J
n
\J
o
o
V
o
o
o
u
0
18,784
Primary heating fuel as derived in Appendix B
from Reference 32 and Table 12.
34
-------
mined in North Dakota and bituminous coal would not be competitive
on a cost basis because of shipping charges (37). Therefore, the
estimated 1,000 lignite-fired residential units located in North
Dakota are assumed to be the only units firing lignite. Lignite
is available in other states and may be burned there in the
residential sector, but information was not available to permit
quantification of these units.
A comparison of coal fields of the United States with the
residential coal consumption by state (Figures 9 and 10) illus-
trates that consumption is greatest in or near major coal regions.
A comparison by consumption per capita and heating units per
capita yields essentially the same results, with West Virginia
having the greatest per capita coal consumption (100 metric tons/
yr-1/000 people) and heating units (16 units/1,000 people).
ANTHRACITE AND MEDIUM AND HIGH LIGNITE
SEMI ANTHRACITE VOLATILE BITUMINOUS COAL
LOW VOLATILE
BITUMINOUS COAL
SUBBITUMINOUSCOAL
Figure 9. Location of U.S. coal fields (28)
«
(37) Personal communication with H. A. Cashion, North American
Coal Corporation, Cleveland, Ohio, 24 January 1977.
35
-------
E$&1 > 100,000 metric tons/yr
g^ 10,000to 100,000 metric tons/yr
I I < 10,000 metric tons / yr
Figure 10. Estimated residential coal consumption
in 1974 by state.
36
-------
SECTION 4
EMISSIONS
Residential combustion of coal produces a number of atmospheric
emissions and a solid residue. Atmospheric emissions include
particulates, sulfur oxides, nitrogen oxides, carbon monoxide,
hydrocarbons, POM's, and individual elements. Emissions are
generated during the combustion process, and with the exception
of a part of the nitrogen oxides, are formed from the coal as it
burns. Some nitrogen oxide is formed by the combination of atmo-
spheric nitrogen and oxygen at high temperatures in the furnace.
The solid residue is composed of inert material (ash) and
unburned or partially burned fuel. If the solid residue is taken
to a landfill for disposal, rainfall may leach out elements into
water supplies.
Air emissions and solid residues are discussed separately in this
section. A general discussion of emissions from three source
types (anthracite, bituminous, and lignite) is followed by a
detailed examination of individual emission species.
AIR EMISSIONS
Characterization of emissions from coal-fired residential combus-
tion sources has concentrated on combustion of bituminous coal
because of its widespread availability and use. Emissions from
residential combustion of anthracite have been measured in only
one test program, while lignite emission factors for residential
combustion have been estimated based on tests on larger combus-
tion systems. Average emission factors for each source type were
developed by compilation of published emission data and emission
estimates. Emissions data were also generated by a sampling
program in which emissions from two bituminous coal-fired resi-
dential combustion units were quantified (15). Original data and
procedures for emission factor development are presented in
Appendix C. Average emission factors were determined for auto-
matic coal-fired heating systems only. Data on hand-fed systems
are limited and do not represent the current trend in coal
heating.
37
-------
The resulting average emission factors are presented in Table 14
(6, 15, 38-40). A comparison of the emission factors for criteria
pollutants developed here with those published by the EPA (40)
is given in Table 15.
Emission factors for SOX and NOX from residential combustion of
bituminous coal compare well with those suggested by EPA (40).
Emissions of hydrocarbons and CO are 2.5 to 3.5 times greater
than those reported by the EPA, but this is understandable because
the EPA values also represent larger units of greater combustion
efficiency (40). The particulate emission factor differs from
that reported by the EPA by a factor of two because the EPA value
is based on coal ash content (40). It is shown later in this
section that the ash content may not directly influence particu-
late emissions from residential combustion units. Average criteria
pollutant emission factors for residential combustion of anthra-
cite coal are generally less than the reported EPA values; how-
ever, a high degree of uncertainty is associated with the average
emission factors developed in this study for anthracite combus-
tion. A comparison for lignite combustion cannot be made because
reliable emission data did not exist and Reference 40 was the
only source of emission estimates for combustion units approach-
ing the residential size range.
Emission data for all three source types were found in the pub-
lished literature, but in several cases the adequacy of the data
was questionable, and these values were not used in determining
average emission factors. No data on the emission of individual
elements could be found, and they were therefore measured through
a special test program (15) . The most reliable emissions data
exist for criteria pollutants from residential combustion of bi-
tuminous coal. Several independent studies have been performed
(38) Hangebrauck, R. P., D. J. Von Lehmden, and J. E. Meeker.
Emissions of Polynuclear Hydrocarbons and Other Pollutants
from Heat-Generation and Incineration Processes. Journal
of the Air Pollution Control Association, 14(7):267-278,
1964.
(39) Hangebrauck, R. P., D. J. Von Lehmden, and J. E. Meeker.
Sources of Polynuclear Hydrocarbons in the Atmosphere.
Public Health Service Publication 999-AP-33 (PB 174 706),
U.S. Department of Health, Education, and Welfare,
Cincinnati, Ohio, 1967. 44 pp.
(40) Compilation of Air Pollutant Emission Factors. Publication
AP-42-A, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, February 1976. 216 pp.
38
-------
TABLE 14. AVERAGE UNCONTROLLED EMISSION FACTORS FOR
AUTOMATIC COAL-FIRED RESIDENTIAL COMBUSTION*
(g of pollutant/kg of fuel)
Emission species
Particulate
SOX
NOX
Hydrocarbons
CO
POM
Polychlorinated
biphenyls
Formaldehyde
Elements ;c
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Tharium
Tin
Titanium
Uranium
Vanadium
ytterbium
Yttrium
Zinc
Zirconium
Bituminous
Emission
factor Reference
4.9 h 6, 15, 40
15.0SD 6, 15, 38
3.9 6, 15, 38
1.8 15, 38, 39
13.0 6, 15, 38
0.058 . 6, 15, 38, 39
<5 x 10~8
0.0012
1.6
0.0008
0.02
0.01
0.0002
0.00001
0.003
0.01
0.0005
0.12
0.72
0.002
0.0007
0.002
0.08
0.005
1.9
0.01
0.003
0.07
0.06
0.0002
0.002
0.002
0.0005
0.009
0.23
0.0005
0.004
2.7
0.00002
0.03
0.01
0.0002
0.00008
0.0005
0.0002
0.09
0.0001
0.002
0.0001
0.001
0.02
0.005
Anthracite
Emission Refer-
factor ence
1.1 . 6
12.0SD 6
0.9 6
1.3 40
8.3 6
0.0001 6
2.0
0.0007
0.005
0.01
0.0002
0.00001
0.001
0.001
0.0002
0.07
1.5
0.002
0.0007
C.003
0.06
0.005
0.44
0.008
0.003
0.06
0.002
0.0002
0.002
0.002
0.0003
0.008
0.24
0.0005
0.003
2.7
0.002
0.05
0.01 .
0.0005
0.004
0.0003
0.0001
0.15
0.0002
0.002
0.0001
0.001
0.012
0.005
Lignite
Emission Refer-
factor ence
13.0 ,
15.0SD
3.0
0.5
1.0
1.0
0.37
0.0002
0.005
0.04
0.00002
0.01
0.00008
1.2
0.17
0.0002
0.0001
0.0005
0.03
0.0008
1.3
0.002
0.0002
0.34
0.005
0.0001
.. 0.002
0.0002
0.0002
0.03
0.02
0.0001
0.0006
0.85
0.001
0.36
0.03
0.0004
0.00004
0.03
0.00007
0.0004
0.00002
0.0003
0.002
0.001
40
40
40
40
40
40
aBlanks indicate no data available.
S is the coal sulfur content in percent.
Emission factors based on the individual element's average coal
concentration and partitioning behavior.
39
-------
TABLE 15. EMISSION FACTORS FOR COAL-FIRED RESIDENTIAL
COMBUSTION AS COMPARED TO THOSE IN AP-42 (40)
Emission factors, £ of pollutant/kg of fuel
Bituminous
Emission
species
Particulate
sox
NOX
Hydrocarbons
CO
This
study
4-. 9
15. OS9
3.9
3.9
17.0
AP-423
11. Od
19. OS9
3.0
1.5
5.0
Anthracite
This
study
1.1
12. OS9
0.9
1.3
8.3
L
AP-42D
5.0
18. 4S9
1.5
1.25
45.0
Lignite
This
study
e
e
e
e
e
AP-42C
13. Of
15. OS9
3.0
0.5
1.0
Spreader stoker units <11 GJ/hr.
Hand-fed units.
c
Stoker-fed other than spreader stoker.
Based on average ash content of 11.0% (Appalachian coal) (20).
eNo data available; used AP-42 (40).
Based on average ash level of 8.6% (20).
9S is the coal sulfur content in percent.
over the past 14 years employing various types of combustion
equipment, grades of bituminous coal, and operating conditions
that together cover the range of conditions expected during ac-
tual operation. Emission factors from combustion of bituminous
coal in each test program are presented in Table 16 by type of
combustion equipment and grade of bituminous coal, when available.
Other pertinent parameters, such as percent excess air and equip-
ment size, are also given. Emission tests of hand-fed units are
included in Table 16 for comparison. The only data rejected from
this study were recent measurements of SOX, particulate, and CO
emissions from a bituminous coal-fired warm-air furnace (41).
The results from that study are not included because of discrep-
ancies found in emission data (i.e., measured SOX emissions
accounted for <2% of the coal sulfur).
(41) Briggs, D. Testing of Particulate and Sulfur Oxide Emis-
sions from a Residential Furnace. Laboratory Number 10638,
Coors/Spectro-Chemical Laboratory, Golden, Colorado,
January 22, 1976. 19 pp.
40
-------
TABLE 16. EMISSION FACTORS FOR RESIDENTIAL SIZE BITUMINOUS COAL
COMBUSTION UNITS FROM INDIVIDUAL TEST PROGRAMS
(g of pollutant/kg of fuel)
Monsanto Research Corporation (15)
Stoker-fed boiler
Emission species
Particulates
Sulfur oxides
Nitrogen oxides
Hydrocarbons
Carbon monoxide
POM
Polychlorinated biphenyl
Formaldehyde
Equipment output capacity, HJ/hr
Operating cycle, min ON/min OFF
Coal feed rate, kg/hr
Excess combustion air, %
Coal ash content, %
Coal volatile content, »
Coal sulfur content, %
Coal heating value, MJAg
Free-swelling index
High volatile
B bituminous coal
Number
Emission factor of
Average Range tests
3.3* 1.5 - 4.1 6
10SC 7. IS - 15S 4
4.56 2.7 - 6.4 6
l.lf 0.93 - 1.4 4
0.8 0.08 - 2.9 6
0.21 0.13 - 0.29 2
_d _d _d
d d d
211
20/40
9.7 - 10
120 - 238
4.3 - 10.9
39.1 - 42.3 :
0.4
26.7 - 28.7
1
Stoker-fed
furnace
High volatile High volatile
C bituminous coal c bituminous coal
Number
Emission factor of Emission factor
Average Range tests Average
2.23 1.1 - 3.1 6 IS8
12SC 5.95S - 18S 5 11SC
2.36 1.0 - 4.0 6 5.1C
1.8f 1.1 - 29 6 3.6f
<2.5 <0.04 - 15 6 11
-" -d -" 0.024
-d -d -d <5 x 10-«9
d _d _d _d
Test conditions
211
20/40
7.0 - 9.6
109 - 221
5.0 - 9.1
37.5 - 38.8
0.6 - 1.5
24.6 - 26.9
0 - O.5
Range
9.7
7.6S
2.7
2.2
. 4.4
0.017
e.e
92
5.0
37.5
0.6
24.6
0
- 25
- 15S
- 11
- 6.0
- 17
- 0.035
_d
_d
211
20/40
- 7.2
- 202
- 9.1
- 38.8
- 1.5
- 26.9
- 0.5
Number
of
tests
8
6
8
4
6
3
1
_d
Western sub-
bituminous coal
Number
Emission of
factor tests
2.03
_d
d
l~8f
d
_d
_d
_d
211
20/40
10
207
3.3
34.7
0.5
22.4
0
1
_d
_d
1
d
_d
_d
_d
(continued)
-------
TABLE 16 (continued)
to
Battelle-Columbus Laboratories'1 (16)
Emission species
Partlculates
Sulfur oxides
Nitrogen oxides
Hydrocarbons
Carbon monoxide
POM
Polychlorinated biphenyl
Formaldehyde
Equipment output capacity, HJ/hr
Operating cycle, min ON/min OFF
Coal feed rate, kg/hr
Excess combustion air, %
Coal ash content, %
Coal volatile content, %
Coal sulfur content, %
Coal heating valve, MJ/kg
Free-swelling index
High volatile
bituminous coal
Number
Emission factor of
Average Range tests
7.4fl 4.6 - 9.0 4
24SC 23S - 2.65 2
3.21 3.0 - 3.3 3
_d _d _d
32 9-69 3
0.1 0.012 - 0.19 4
_d _d _d
_d _d _d
720
20/40
10 - 34
30 - 116
4.7
'- 40
1.2
32. a
5
Stoker-fed boiler
Western
subbituminous coal
Number
Emission factor of
Average Range tests
1.6a 0.95 - 2.2 5
18SC 13S - 23S 2
2.61 2.1 - 3.0 3
_d _d d
15 9.3-18 .4
0.016 0.008 - 0.022 4
_d _d d
_d _d _d
Test conditions
720
20/40
11 - 34
40 - 190
9.2
37.4
0.6
26.5
0.5
Low volatile
bituminous coal
" Number
Emission
factor ti
•3.18
d
4.61
_d
10
0.06
_d
_d
720
20/40
23
132
6.9
21.4
0.6
34.1
7.5
of
ests
1
_d
i
_d
1
1
_d
_d
(continued)
-------
TABLE 16 (continued)
co
Hangebrauck - 1967 (39)
Emission species
Particulates
Sulfur oxides
Kitrogen oxides
Hydrocarbons
Carbon monoxide
PON
Polychlorinated biphenyl
Formaldehyde
Equipment output capacity, MJ/hr
Operating cycle, nin ON/min OFF
Coal feed rate, kg/hr
Excess combustion air, %
Coal ash content, %
Coal volatile content, %
Coal sulfur content, %
Coal heating valve, MJ/kg
Free-swelling index
Stoker-fed boiler
Bituminous coal
Nunber
Emission factor of
Average Range tests
d d d
_d _d _d
d d d
1.9^ 1.4 - 2.4 2
d d d
O.038 0.031 - 0.045 2
d d d
d d d
d
60/0
1.7 - 1.9
d
4.D
d
33.2
d
d
Stoker- fed furnace
Bituminous coal
Kvnber
Emission factor of
Average
d
_d
d
0.46^
d
0.016 0
d
d
Test
Range tests
d d
_d _d
d d
0.3 - 0.6 2
d d
.006 - 0.026 2
_d _d
_d _d
conditions
d
60/0
2.0 - 2.3
_d
2.4
_d
32.5
_d
d
~
Hand-fed furnace
Bituminous coal
Emission' Factor
Average Range
d • d
_d _d
d d
8.2^ 5.3 - 11
d _d
0.83 0.46 - 1.2
_d _d
_d _d
_d
60/0
2.5 - 2.9
d
2.9
_d
33.0
d
_d
ttunber
of
tests
d
_d
d
2
_d
2
_d
_d
(continued)
-------
TABLE 16 (continued)
Emission • species
Particulates
b
Sulfur oxides
Nitrogen oxides
Hydrocarbons
Carbon monoxide
POM
Polychlorinated biphenyl
Formaldehyde
Equipment output capacity, MJ/hr
Operating cycle. Din ON/min OFF
Coal feed rate, kg/hr
Excess combustion air, %
Coal ash content, t
Coal volatile content, %
Coal sulfur content, %
Coal heating valve, MJ/kg
Free-swelling index
Hangebrauck
Stoker-fed boiler
Bituminous coal
Number
Emission of
factor tests
6k
r
16S 1
4.96 1
1.7 1
16 1
0.003 1
d d
d d
169
60/0
2.2
417
3.9
1.0
31.9
38
d
- 1964 (38)
Hand-fed furnace
Bituminous coal
Number
Emission of
factor tests
19k
p
16SC 1
1.66 1
11 1
50 1
0.13 1
d d
0.0012 1
Test conditions
.211
60/0
3.6
538
2.7
0.5
33.4
38
d
Snowden (30)
Fireplace
Bituminous coal
Number
Emission of
factor tests •
7.09 1
rt rl
u u
_d _d
7 4f 1
j _d
d d
d d
d d
_d
_d
0.5
d
d
d
d
d
d
*Front half of EPA Method 5 only.
Reported as SOa.
S is sulfur content of fuel in
weight percent.
No measurement made or reported.
Reported as N02.
Determined condensed organic material
residue weight in the EPA Method 5
impinger train.
"Detection limit.
Barometric damper sealed shut.
Reported as NO.
^Benzene soluble fraction of organic
material trapped in a 32°F and -98°F
bubbler system.
L
Includes front and back half material
from EPA Method 5 characterization.
^
Reported as methane determined by
flame ionization.
-------
Emission data for residential combustion of anthracite coal were
obtained from one study in which two tests were conducted.
Because of the limited emission data, the average emission fac-
tors are highly uncertain. However, based on comparison with
bituminous coal-fired emissions, it is anticipated that the
actual average emission factors for anthracite combustion do not
exceed the uncertainty limits given in Table 14.
Criteria pollutant emission factors presented for residential
combustion of lignite are estimates suggested by the EPA because
emission data could not be obtained for this source type. Par-
ticulates and SOX were measured in one recent test on a 106 MJ/hr
furnace burning lignite (42), but the particulate emission factor
of 1-0 gAg could not be supported by other data and is an order
of magnitude below that suggested by the EPA based on coal ash
content. The SOX emission factor of 15S g/kg is reasonable,
based on studies of other coal types, and closely agrees with EPA
estimates. An additional study measured particulate emissions on
a commercial/institutional size lignite-fired boiler and found an
average particulate emission factor of 13 g/kg (43). Although
much larger than residential units, this boiler is still rela-
tively small and its emission may approximate those from residen-
ential units. The order of magnitude discrepancy between the
particulate emission factors for the two studies indicates that
there are insufficient data to substantiate whether either study
is representative of residential emissions.
Emissions of individual elements from coal-fired residential
combustion units had not been measured prior to this study. A
special project (15) related to this investigation included mea-
surement of emissions of individual elements from two coal-fired
units burning a limited range of bituminous coals. Because coal
elemental content can vary by several orders of magnitude, these
data are too limited to represent average elemental emission
factors for residential combustion of bituminous coal. However,
the elemental emission data were used in conjunction with the
associated coal analysis to estimate the upper limits of coal
elements emitted to the atmosphere. A more detailed explanation
is presented later in this section.
aS is coal sulfur content.
(42) Sulfur in Colorado Lignite. Cameron Engineering, Inc.,
Denver, Colorado, June, 1977.
(43) Results of the August 16, 1977 Particulate emission Com-
pliance Test of the Beulah High School No. 3 Boiler, Beulah,
North Dakota. Report Number 7-334, Interpoll, Inc., St.
Paul, Minnesota, August 31, 1977. 24 pp.
45
-------
Emission factors for coal-fired residential combustion are in-
fluenced by many variables, but in general the data suggest that
burning anthracite or western subbituminous coal in a stoker-fed
unit has the least environmental impact. Choosing the proper
equipment design and burning the coal most suited for the equip-
ment are other important considerations. Emission rates for
species are directly or indirectly affected by specific para-
meters of coal type and equipment design and operation. These
parameters interact in a complex manner and make prediction of
emission factors based on parameters a difficult task. The
following discussion of each emission species reports what is
presently known about those factors that affect emission rates.
It is based, for the most part, on observations from testing
programs burning bituminous coals.
Particulates
Particulate emissions consist of small, discrete masses of solid
or liquid leaving the exhaust stack of residential combustion
equipment. The most frequently employed method for collection
and quantification of these emissions is the EPA Method 5 (44).
This system collects particulates in two fractions, segregating
solid particles (front half) from condensed vapors (back half).
Most studies have reported material collected in the front half
as particulate emissions. This report remains consistent with
that practice and classifies the material collected in the back
half as organic emissions. Reference 38 reported the total
material collected as particulate emissions and therefore was
excluded in the calculation of the average particulate emission
factor.
Estimates of particulate emission factors for coal-fired residen-
tial combustion are in terms of the coal ash content; however, it
has been demonstrated that ash content may not directly affect
particulate emissions (15). Analysis of particulates for carbon/
hydrogen, and nitrogen before and after extraction with methylene
chloride (CH2C12) (Table 17) demonstrates that particulate emis-
sions contain unextractable carbon in approximately the same
concentration as that in the feed coal (15).
The carbonaceous nature of the particulate emissions explains the
lack of correlation between particulate emission factors and coal
ash content. In large coal-fired combustion units (e.g., utility
boilers), particulate emissions arise from inorganic matter (ash)
contained in the coal. However, in residential units the com-
bustion process is less efficient, and particles are apparently
formed by volatilization and subsequent condensation of carbo-
naceous matter in the coal. This hypothesis is supported by the
(44) Standards of Performance for New Stationary Sources.
Federal Register, 42(160):41776-41782, 1977.
46
-------
TABLE 17. AVERAGE CARBON, HYDROGEN, AND NITROGEN CONTENT
OF PARTICULATE EMISSIONS FROM COAL-FIRED
RESIDENTIAL HEATING SYSTEMS (15)
Composition,
percent of particulate
Sample identification Carbon Hydrogen Nitrogen
Particulate train filter catch
before extraction with CHaCla 80.1 1.4 0.7
Particulate train filter catch
after extraction with CH2C12 79.8 1.2 0.5
positive correlation observed between particulate emission fac-
tors and coal volatile content (15). However, because this
observation was made on a narrow range of coal volatile content,
it requires further study over a broader range of coal types for
verification.
It is also suspected that burning coals with high free-swelling
index may adversely affect particulate emission factors (15).
High free-swelling index coals have a greater tendency to agglo-
merate, thereby creating conditions for incomplete combustion.
This finding is also supported by the carbonaceous nature of
particulate emissions and demonstrates the importance of combus-
tion efficiency with respect to particulate emissions.
<3ul.fur Oxides
Sulfur oxide emission factors are presented in terms of coal
sulfur content which is the limiting and single most important
variable affecting the formation of SOX. Typically, 70% of the
coal sulfur content is emitted as gaseous sulfur oxides, as
demonstrated in Figure 11 (15). The point falling above the
maximum SOX line (calculated S02 emissions based on coal sulfur
content) is in error either in emission rate determination on in
coal sulfur content determination. The low SOX emission factor
for the 1.5% sulfur coal may be the result of calcium in the coal
combining with the sulfur, thereby reducing the formation of SOx.
The 1-5% sulfur coal was found to contain 50% more calcium than
the 1% sulfur coal from the same study.
tJj.hrggen Oxides
Emissions of nitrogen oxides are dependent on many variables
Delated to the combustion process, and extensive testing would
be required to determine the effect of these variables on NOX
emission rates. At the low combustion temperatures attained in
residental combustion «1,800°K), 60% to 100% of the NOX emitted
47
-------
REFERENCE 15
REFERENCE 6
REFERENCE 38
CURVE BASED ON STOICHIOMETRIC
CONVERSION OF TOTAL SULFUR IN
COAL TO SULFUR DIOXIDE
0.5
1.0
SULFUR CONTENT OF COAL, t
1.5
2.0
Figure 11.
Effect of coal sulfur content
on SOX emissions.
is formed from fuel nitrogen, and the remaining nitrogen is pro-
vided by combustion air (45). Most of the NOx emissions are in
the form of nitric oxide (NO); nitrogen dioxide (N02) accounts
for the remainder.
Hydrocarbons
Measurement of hydrocarbon emissions from coal-fired residential
combustion equipment has been limited to units burning bituminous
coal (15, 30, 38, 39). In addition, hydrocarbon collection tech-
niques employed in the cited studies have differed somewhat
from each other, although most rely on condensation of organic
material in traps held below 0°C. These techniques collect the
higher molecular weight hydrocarbons but allow the lower
molecular weight ones to pass through. One study employed a
hydrocarbon measurement technique (flame ionization) that also
measured low molecular weight hydrocarbons (38). Emission factors
determined from these measurements were of the same magnitude as
those determined from the condensation technique indicating that
condensation collects a substantial portion of the hydrocarbon
species emitted. However, the lack of more complete emission
data on lower molecular weight hydrocarbon emissions prevent any
definite conclusion as to the actual total hydrocarbons emitted
from coal-fired residential combustion. Based on the available
(45) Vogt, R. A., and N. M. Laurendeau. Nitric Oxide Formation
in Pulverized Coal Flames. PURDU-CL-76-08 (PB 263 277),
National Science Foundation, Washington, D.C., September
1967. 92 pp.
48
-------
data, the condensation techniques probably accounts for at least
50% of the total hydrocarbons. In addition, many of the environ-
mentally significant hydrocarbons such as POM compounds have been
collected and quantified by the condensation techniques. The
addition of a porous polymer trap improves the collection effi-
ciency of these compounds (6, 15) .
Hydrocarbon emissions appear most affected by combustion equip-
ment. The average hydrocarbon emission factor for the hand-fed
units tested (including fireplaces) was about five times higher
than the average from stoker-fed units. Because hydrocarbon
emissions are a result of incomplete combustion, this difference
can be explained by comparing the natures of hand-fed combustion
(overfeed) and stoker-fed combustion (underfeed) , described in
detail in Section 3. Hydrocarbon emissions species have been
characterized by collection on a polymeric resin, designed for
organic material entrapment, and subsequent analysis by a gas
chroma tograph/mass spectrometer (GC/MS) (15) .
Table 18 lists the more than 50 organic compounds identified in
one test program (15) . The emission factors for each species are
also provided. These emission factors represent the average of
results from a test on a coal-fired boiler and a test on a coal-
fired furnace. The analysis of a coal tar sample, performed by
jyiRC for a commercial customer in another program, is presented
in Table 19 for comparison. As noted, the tar from a coal
gasification process is very similar in composition to the organic
material condensed from the flue gas generated in residential
coal combustion. These results support the conclusion that
residential coal combustion is incomplete and that coal volatiles
are vaporized, escaping into the atmosphere unburned.
Monoxide
Emissions of carbon monoxide from coal-fired residential combus-
tion equipment are highly variable, ranging from <0.04 g/kg to
69 9/k?' These values are high compared to those for larger
C0al-fired industrial and utility boilers [0.5 g/kg to 1.0 g/kg
(40) ]/ indicating a lower combustion efficiency for the residen-
tial units. This occurs in spite of the high excess-air levels
frequently found in residential combustion. The best explanation
for poorer residential combustion performance is found in the
geometry of the fuel combustion unit. Unlike larger utility
boilers where coal is pulverized and burned as small discrete
particles suspended in a high-temperature gas stream, residential-
size units burn coal in a pile which can have many pockets of
incomplete combustion caused by localized oxygen deficiencies.
AS expected, the highest level of CO emissions was observed from
nd-fed units (38, 39).
49
-------
TABLE 18. MAJOR ORGANIC SPECIES EMITTED FROM RESIDENTIAL
COMBUSTION OF BITUMINOUS COAL (15)
Average
emission
factor,
Identified compound q/kg
Ci-alkylbenzenes 0.022b
C.-alkylbenzenes 0.010
Indane 0.001b
Methylfndenes 0.015
Phenol 0.042
Methyl phenol 0.055b
Dimethyl phenol 0.041b
Ca-alkyl phenol 0.009
Naphthalene 0.15
Methylnaph'thalenes 0.12
Dimethylnaphthalenes 0.11
Cs-alkylnaphthalenes 0.057
CM-alkylnaphthalenes 0.017
Cs-alkylnaphthalenes 0.007
Biphenyl 0.006
Acenaphthene 0.039
Pluorene 0.026
Methylfluorene 0.016b
Phenyl phenol 0.002b
Benzofuran 0.002
Methylbenzofuran 0.01
Fluorenone 0.011b
Di-t-butyl oresol 0.008
Methyl resoroinols °-05 b
Anthraguinone 0.003b
Methyl laurate 0.001b
Methyl myristate 0.001b
d,-alkyl phenol 0.003
Methyl palmitate 0.003
Methyl stearate 0.002fa
Di-Ca-alkylphthalate 0.015
Di-Cj-alkylphthalate 0.0007
Di-C.-alkylphthalate 0.0008
Di-2-ethylhexylphthalate 0.01
Dioctylphthalate 0.076
Aliphatics (Ci» to Cjs) 1.5
POM:
Dibenzothiophene 0.0002
Anthracene/phenanthrene 0.016
Methylanthracenes/phenanthrenes 0.01
9-Methylanthracene 0.0002
Dimethylanthracenes/phenanthrenes 0.008
Fluoranthene 0.005
Pyrene 0.005
Methylfluoranthenes/pyrenes 0.003
Benzo(c)phenanthrenec 0.0002
Chrysene/benz(a)anthracene c j 0.004
7,12-Dimethylbenz(a)anthracene ' 0.083
Benzofluoranthene(s) 0.004
Benzopyrene(s) (and nerylene) 0.003
3-Methylcholanthrenen>£ 0.002
Indenod^.a-cdjpyrene1- 0.002
Dibenz(a,h)anthracene°»c 0.003
Dibenzo(c,g)carbazole <0.0001
Dibenzopyrenescd 0.009
Methylchrysenes ' 0.005
Cu-alkylphenanthrene 0.002
Total 2.6
"Average of two samples.
Only identified in one sample.
These groups contain known carcinogens (46).
May include isomers.
eQuantitation based on response of benzo-
fluoranthene.
(46) Biologic Effects of Atmospheric Pollutants - Particulate
Polycyclic Organic Matter. National Academy of Sciences/
Washington, D.C., 1972. 361 pp.
50
-------
TABLE 19. ANALYSIS OF COAL TAR SAMPLE FROM
COAL GASIFICATION PROCESS3
Organic species Amount,^ pg
Phenol 61
Methylphenols 281
Dimethylphenols 131
Trimethyl (or methylethyl) phenols 56
Methylindanes 12
Dimethylindanes 12
Methylbenzaldehydes 11
Dimethylbenzaldehydes 11
Naphthalene 23
Methylnaphthalenes 109
Dimethylnaphthalenes 172
Acenaphthene 115
Fluorene 202
Naphthols 101
Methyl naphthols 149
Dimethyl naphthols 80
Trimethylnaphthalenes 139
Benzofuran 40
Tetramethylnaphthalenes 13
Pentamethylnaphthalenes 13
Methylbenzofurans 76
Dimethylbenzofurans 48
Methylfluorenes 112
Trimethylbenzofurans 29
Anthracene/phenanthrene 128
Methylanthracenes/methylphenanthrenes 248
Dimethylanthracenes/dimethylphenanthrenes 95
Pluoranthene 33
Pyrene 32
Dibenzofurans 31
Kethylfluoranthenes/methylpyrenes or benzofluorenes 176
DimethyIfluoranthenes/dimethylpyrenes 95
Methyldibenzofurans 109
Dimethyldibenzofurans 122
Cu-alkylanthracenes/C<,-alkylphenanthrenes 47
Benzo(c)phenanthrene ' 22
Chrysene/benz(a)anthracene . 94
C3-alkylfluoranthenes/C3-alkylpyrenes 47
Methylbenzanthracenes (or isomers) 409
Cholanthrene 124
Dimethylbenzanthracenes (or isomers) 606
C3-alkyldibenzofurans 53
Benzofluoranthenes 72
Benzopyrenes/benzoperylene 67
Methylcholanthrenes 220
Dibenzofluorenes 207
Dibenzanthracenes 35
Benzo(ghi)perylene 33
Dimethylcholanthrenes 143
Methyldibenzofluorenes 114
Methyldibenzanthracenes 75
Methylbenzo(ghi)perylenes 51
Dimethyldibenzanthracenes 50
Ca-alkyldibenzanthracenes 12
Dibenzopyrenes 92
Total 5f638
In-house analysis performed by MRC for commercial customer in
another program.
Relative amounts found using gas chromatography/mass spectrometry.
51
-------
POM and PCB
Emissions of polynuclear organic materials (POM's) from residen-
tial coal combustion are significant and should be of some concern.
POM emission factors from coal-fired residential combustion are
at least two orders of magnitude greater than those from larger
combustion sources and other residential fossil-fuel units, as
shown in Table 20 (2).
TABLE 20. POM EMISSION FACTORS FROM COAL-FIRED RESIDENTIAL
COMBUSTION COMPARED TO OTHER COMBUSTION SOURCES (2)
Combustion Approximate
source POM emission
type factor ,a pg/J
Residential: ,
Bituminous coal 1,900
Gas 1.0
Oil 4.2
Commercial/Institu-
tion, coal 19
Industrial, coal 10
Utility, coal 0.8
These values were derived from
data in Reference 2 as explained
in Appendix D.
Value determined in this study.
POM formation during combustion is strongly dependent on combus-
tion efficiency (47), which is known to vary widely, not only
from unit to unit, but also within individual units. Conditions
necessary for complete combustion of POM's are sufficient time
for completion of chemical reactions, sufficient temperature to
heat all of the fuel through its decomposition stages and to
ignite it, and sufficient turbulence to thoroughly mix the com-
bustible material and oxygen. In spite of high excess-air levels
associated with residential combustion, nonuniform fuel beds and
deviation from the above combustion criteria favor the formation
of POM's. Excess air levels that are too high, although providing
sufficient oxygen for complete combustion, also may favor POM
(47) Knierman, H., Jr. A Theoretical Study of PCB Emissions from
Stationary Sources. Contract 68-02-1320, Task 26, U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, September 1976. 38 pp.
52
-------
formation by faster quenching in the post-flame region and by
reducing retention times in the combustion chamber. Consequently/
POM measurements within each test program are highly variable as
shown in Table 16. In addition, the average POM emission factors
for each test cover two orders of magnitude. This inverse
relationship of POM formation to combustion efficiency accounts
for the higher POM emission rates from hand-fed units and the OFF
portion of a heating cycle (15). The effect of heating cycle on
emissions is discussed later in this section.
Besides combustion equipment, coal parameters may also influence
POM emissions. For example, an increase in POM emissions has been
observed with increasing percent of volatile material in the coal
(15). The supporting data cover a narrow range of coal volatile
matter and, therefore, require further testing for confirmation.
Emissions of individual POM compounds from residential combustion
of coal were presented in Table 18 for limited test conditions.
About 65% (by mass) of the POM emissions were known carcinogens,
indicating the carcinogenic nature of the POM emission factor
Developed in this study.
polychlorinated biphenyls (PCB's) were not found in the emissions
from a residential bituminous coal-fired unit and were not tested
in anthracite and lignite combustion. Based on the sensitivity
Of the analytical technique (GC/MS), PCB compounds, if present,
are emitted at less than 5 yg/kg of coal (15).
Tndividual Elements
Emissions of individual elements from the residential combustion
Of two bituminous coals have been measured, and results are
presented in Table 21 (15). Because of the high variability in
coal elemental content, these emission factors cannot be used to
represent emissions from the whole population. Emission factors
for individual elements, however, were used to estimate the
fraction of specific elements present in coal that is emitted to
tke air upon combustion. This fraction was then applied to an
average coal elemental composition to predict average emission
factors for individual elements. The emission data suggest that
the upper limit of the emission factor for each nonvolatile
element is about 10% of the concentration of that element in
coal- The actual value in most cases is probably less than 5%,
hut there are insufficient supportive data to prove this.
Tahle 22 lists the elemental emission species that were evaluated
and gives each one's fraction of coal content estimated to be
emitted upon combustion. This fraction times the concentration
^ that element in the three average coal types (Table 9, 10,
and ID was USfid to calculate the emission factors presented in
14.
53
-------
TABLE 21. EMISSION FACTORS FOR INDIVIDUAL ELEMENTS
FROM BITUMINOUS COAL-FIRED RESIDENTIAL
HEATING EQUIPMENT (15)
(g of pollutant/kg of fuel)
Element
emitted
Aluminum
Antimony
Arsenic
Barium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Phosphorus
Selenium
Silicon
Silver
Sodium
Strontium
Tin
Titanium
Vanadium
Zinc
Residential
- boiler burning
Utah bituminous coal
0.007
<0.0005a
0.0004
0.0003
0.002
<0.002a
0.012
<0.005a
<0.0005a
<0.0005a
0.017
<0.003a
0.002
0.0003
0.0001
<0.0001a
0.00005
<0.009a
<0.002a
0.002
<0.0005a
0.009
<0.0004a
0.003
0.002
<0.002a
0.003
Residential
furnace burning
Wyoming bituminous coal
0.085
<0.016a
0.001
0.007
0.017
<0.0004a
0.16
0.002
<0.0005a
0.003
0.1
<0.007a
0.047
0.001
0.0003
<0.02a
_ ... _ a
<0.02a
<0.014a
0.0005
0.09
<0.033a
<0.006a
0.002
<0.037a
0.007
0.003
0.014
Value is based on the detection limit.
54
-------
TABLE 22. FRACTION OF ELEMENTS IN COAL EMITTED TO THE
ATMOSPHERE DURING RESIDENTIAL COMBUSTION
Fraction of coal
Emission content emitted to
species air, % Basis
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
10
75
75
10
10
10
10
100
75
10
100
10
10
10
100
75
10
75
10
10
10
100
75
10
10
10
10
10
75
10
50
10
10
50
75
10
10
10
10
10
10
10
75
10
A
B
A, B
A
C
B
C
B
B
A
B
A
A, B
A
B
B
A
B
C
A
A
A. B
A, B
B
B
A
B
B
B
B
C
B
A
C
B
B
B
A
B
A
C
B
B
B
Reference
15
48-51
15, 48-51
15
48-51
48-51
48-51
48-51
15
48-51
15
15, 48-51
15
48-51
48-51
15
48-51
15
15
15, 48-51
15, 48-51
48-51
48-51
15
48-51
48-51
48-51
48-51
48-51
15
48-51
48-51
48-51
15
48-51
15
48-51
48-51
48-51
Estimate based on sampling data from western bitu-
minous coal.
Estimate based on partitioning behavior in larger
combustion units.
Estimate based on position of element in periodic
table relative to other elements of known
partitioning behavior.
(48) McCurley, W. R., R. B. Reznik, and J. Ochsner. Source
Assessment: Pulverized Bituminous Coal-Fired Dry Bottom
Industrial Boilers. Contract 68-02-1874, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
(Unpublished draft report prepared by Monsanto Research
Corporation, May 1978.)
(continued)
55
-------
Elements not accurately characterized in Reference 15 were deter-
mined from other references based on their general partitioning
behavior presented in Table 23 (48-51). Elements expected to be
largely volatilized during combustion were assumed to be 100%
emitted as an upper limit, while those elements expected to
concentrate in fly ash because of partial volatilization and
subsequent condensation were assigned an upper limit of 75%.
TABLE 23. CLASSIFICATION OF ELEMENTS ACCORDING
TO THEIR PARTITIONING BEHAVIOR (49-51)
Partitioning class Elements
Class I - Elements equally distri- Aluminum, barium, bismuth, calcium,
between bottom and fly ash cobalt, iron, magnesium, man-
ganese, niobium, potassium,
scandium, silicon, strontium,
thorium, tin, titanium, yttrium,
zirconium
Class II - Elements concentrating in Antimony, arsenic, cadmium, copper,
fly ash gallium, lead, molybdenum,
selenium, thallium, zinc
Class III - Elements remaining in gas Bromine, chlorine, fluorine, mer-
phase cury
Elements intermediate between Chromium, nickel, sodium, uranium,
Classes I and II vanadium
(continued)
(49) Davison, R. L., D. F. S. Natusch, J. R. Wallace, and C. A.
Evans, Jr. Trace Elements in Fly Ash - Dependence of
Concentration on Particle Size. Environmental Science and
Technology, 8(13):1107-1113, 1974.
(50) Kaakinen, J. W., R. M. Jorden, M. H. Lawasani, and R. E.
West. Trace Element Behavior in Coal-Fired Power Plant.
Environmental Science and Technology, 9(9) :862-869, 1975.
(51) Klein, D. H., A. W. Andren, J. A. Carter, J. F. Emery,
C. Feldman, W. Fulkerson, W. S. Lyon, J. C. Ogle, Y. Talmi,
R. I. VanHook, and N. Bolton. Pathways of Thirty-Seven Trace
Elements Through Coal-Fired Power Plant. Environmental
Science and Technology, 9(10):973-979, 1975.
56
-------
Emissions Affected by Operating Cycle
Automatic coal-fired heating equipment differs from other forms
of automatic heating in that a bed of fuel continued to burn when
the demand for heat is satisfied and the combustion-air fan shuts
off- Consequently, the equipment continues to release pollutants
to the atmosphere during the OFF period. However, combustion and
the flue gas composition are not the same as during the ON period.
Two test programs have investigated emissions from each cycle
segment for bituminous coal combustion (6, 15); however, results
from Reference 6 are not discussed here because of the atypical
operation of the barometric damper. Both studies indicate that
variations in the ON/OFF cycle can alter the overall emission
factors.
Table 24 presents a comparison of average emission data obtained
from each cycle segment during testing of a bituminous coal-fired
warm-air furnace (15). Emission rates are presented rather than
emission factors because it was impossible to measure separately
the actual quantity of coal burned during the ON and OFF segments
of the heating cycle.
Emission rates for all emission species were higher during the
ON segment except for POM emissions which were about three times
higher in the OFF segment. Because POM emissions are products
of incomplete combustion of volatiles, this finding was not un-
expected. Carbon monoxide is also a product of incomplete com-
bustion and should be generated in the largest amounts during the
OFF period when insufficient oxygen exists for stoichiometric
combustion. This relationship was seen in Reference 6, but the
opposite condition occurered in Reference 15.
The difference in CO emission rates cannot be fully explained,
although the operation of the barometric damper may be the key to
any logical explanation. The position of.the barometric damper
can play an important role in determining the nature and extent
Of combustion during the OFF segment. In Reference 15, sampling
was conducted with the barometric damper free to open and close
when the stack pressure drop varried as it would in actual opera-
tion. As a result, a minimum amount of draft was induced through
the combustion chamber. In contrast, sampling in Reference 6 was
conducted with the barometric damper fixed closed. Draft induced
in the exhaust stack thus pulled air through the combustion cham-
fter, causing residual fuel to burn more rapidly. It might be
expected, therefore, that this higher combustion rate during the
OFF segment generated more CO than when the damper was allowed
to open, because a greater quantity of coal burned at less than
desirable combustion conditions.
57
-------
TABLE 24. AVERAGE EMISSION RATES FOR A 20-MINUTE ON AND
40-MINUTE OFF HEATING CYCLE OF A RESIDENTIAL
BITUMINOUS COAL-FIRED COMBUSTION UNIT (15)
(g/hra)
Heating cycle segment
Emission species
Particulates
SOX
NOX
CO
POM
Condensable organics
Elements:
Aluminum
Antimony
Arsenic
Barium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Phosphorus
Selenium
Silicon
Silver
Sodium
Strontium
Tin
Titanium
Vanadium
Zinc
ON
83
76
28
58
0.026
13
0.39 b
<0.022
0.009
0.025
0.068 ..
<0.0003D
0.82
0.008
0.003
0.014
0.59 .
<0.007
0.29
0.007 ,
<0. 00003°
<0.038b
<0.022J>
<0.031
0.003
0.19b
<0.12D
0.054
0.011.
<0.095
0.044
0.006
0.073
OFF
16
4.5
5
14
0.077
6
0.12 .
<0.054
0.003
0.009
0.023.
<0.002°
0.059
0.0095
0.005.
<0.001
0.068.
<0.037
0.016 .
<0.0005
0.002.
<0.014D
0.059.
<0.032P
<0.005D
0.23 .
<0.03oP
<0.024P
<0.001
<0.15b
<0.005D
0.006.
<0.009
Emissions are presented as kilograms per
hour rather than grams per kilogram because
quantifying the amount of coal combusted
during each cycle segment was not possible.
Value is based on the detection limit.
58
-------
Emissions data from Reference 15 were determined for heating
equipment operating at a 20-min ON/40-min OFF heating cycle.
This cycle was determined to be representative of the average
total ON and total OFF time for a heating season (see Appendix A).
Furnaces controlled by thermostat may have ON/OFF cycles of
shorter duration. Extrapolation of the data to predict emissions
for other heating cycles is possible if the emission rates are
not strongly dependent on the length of the ON and OFF periods.
Although variations in the heating cycle were not studies, it is
believed that conditions during the ON and OFF periods approxi-
mate steady-state conditions. Emission factors for the lower
percentages of ON time are representative of the early and late
parts of the heating season while the emission factors for high
percentages of ON time represent the coldest part of the heating
season.
SOLID RESIDUES
Combustion of coal in residential heating equipment produces a
solid residue consisting of inorganic material (coal ash) and
unburned or partially burned coal. The following discussion is
based on the quantification and characterization of solid resi-
dues from a boiler and warm-air furnace burning high volatile
bituminous coal (15).
Ash Quantification
The coal-fired boiler studied had no provisions for physical
separation of ash from fuel, and any attempt to quantitatively
recover ash resulted in removal of partially burned coal from
the fuel bed or incomplete recovery of ash. A fused mass of ash
removed from the boiler included pieces of partially combusted
coal. The coal-fired warm-air furnace was equipped with a
slide-out ash pan located below the fuel bed which permitted
recovery and quantification of solid residue.
Quantities of ash residue recovered from the combustion of
bituminous coal in the warm-air furnace are listed in Table 25
as grams of residue per kilogram of coal burned. Because the
amount of residue is greater than the ash content of the coal,
the combustion process must be incomplete, with unburned coal
Cropping into the ash pan. Three samples of residue were
analyzed and found to contain from 15% to 56% unburned coal, or
44% to 85% actual ash. This accounts for the high variability of
residue recovery.
Because no other coals were tested, the representativeness of
these results is unknown. However, it can be assumed that
different results will be obtained from burning other grades of
coal or using different combustion equipment where agglomerating
tendencies and combustion efficiencies differ.
59
-------
TABLE 25. ASH RESIDUE FROM COMBUSTION OF BITUMINOUS
COAL IN A WARM-AIR FURNACE (15)
(gAg)
Test
number
13
14
17
18
22
25
Coal
ash
content
50
50
91
91
91
71
Average
ash
residue
300
121
155
149
118
110
Elemental Composition
Elements present in coal burned in residential heating equipment
which are not emitted in the flue gas remain in the solid residue
either as unburned coal or nonvolatilized inorganic ash. The
elemental composition of this material is presented in Table 26
for residue from a warm-air furnace burning bituminous coal (15).
TABLE 26. CONCENTRATION OF ELEMENTS IN THE ASH RESIDUE FROM
A BITUMINOUS COAL-FIRED WARM-AIR FURNACE (15)
Element
Average concentration
in residue, %
Aluminum
Antimony
Arsenic
Barium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Phosphorus
Selenium
Silicon
Silver
Sodium
Strontium
Tin
Titanium
Vanadium
Zinc
aAverage of two
bValue is based
3.4
0.016
0.001
0.084
0.012
0.0007
2.6
0.018
0.009
0.034
2.7
0.012
0.83
0.029
<0. 0000004"
0.004
0.025
0.17
0.005C
0.011
0.017
0.13
0.075
0.007
0.3
0.034
0.016
samples.
on the detection limi
Value is that of the reagent blank
used as upper limit.
60
-------
POTENTIAL WATER POLLUTANTS
The elemental content of ash residue may be an environmental
problem if the ash is exposed to rainfall and elements in the
ash leach out and enter water supplies. A test was conducted on
residue from a warm-air furnace to estimate the relative leach-
ability of elements from coal-fired residential combustion
residue (15). Ash was shaken for 24 hours in distilled water at
an ash-to-water ratio of 1 to 10, and the elemental content of
the water was determined after shaking. Final pH of the water
rose to 11.6 from an initial pH of 7.1, reflecting the alkalinity
of the ash and high calcium content of the coal.
Relative leachability of the elements found in ash residue is
presented in Table 27 as grams leached per kilogram of ash and
as percent of element leached from ash (15). About half of the
elements were found to be below the detection limits, corre-
sponding to leaching of less than 0.001 g/kg; some values were
as low as less than 0.0001 g/kg.
TABLE 27. RELATIVE LEACHABILITY OF INDIVIDUAL
ELEMENTS FROM COAL-FIRED RESIDENTIAL
COMBUSTION RESIDUE (15)
Element
Amount leached
per quantity
of ash, g/kg
Fraction of element
in ash leached
to water, %
Aluminum
Antimony
Barium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Phosphorus
Selenium
Silicon
Silver
Sodium
Strontium
Tin
Titanium
Vanadium
Zinc
0.012
<0.002
0.019
0.002
<0. 00005
5.8
<0.00002
<0.0001
<0.0001
<0. 00001
<0.0005
0.002
<0. 00001
<0. 00002
o.doi
<0.0005
<0.001
0.0003
0.047
<0.0004
1.2
0.15
<0.0004
<0. 00002
<0. 00005
<0. 00002
0.035
<0.13
2.3
1.9
<0.77
23
<0.011
<0.12
<0.029
<0. 00004
<0.42
0.024
<0.004
<92
2.0
<0.20
<0.059
74
45
<0.23
91
20
<0.62
<0.0007
<0.015
<0.013
Although this type of test may be considered a worst case because
it does not address the rate of leaching, it is indicative of the
types of material that can be leached in the greatest quantity.
61
-------
POTENTIAL ENVIRONMENTAL EFFECTS
Air emissions from coal-fired residential combustion sources have
their greatest potential environmental effect when at the maximum
ground level concentration. Unlike larger combustion systems
(i.e., utility boilers) which have tall stacks to disperse emis-
sions and reduce ground level concentrations, residential units
release emissions close to ground level where dispersion is
minimal. Although the maximum ground level concentration from
a single emission source may be relatively high, its distance
from the emission point is such that few people are exposed to
that concentration.
Unique to residential combustion, however, is the potential for
multiple sources such as in a housing subdivision. In this case,
emissions from many coal-fired heating devices have an additive
effect that increases the maximum ground level concentrations
and covers more land area with a high population density. The
potential environmental effects of air emissions from coal-fired
residential combustion systems were evaluated using source
severity, affected population, state emission burdens, and
national emission burdens as discussed below.
Source Severity
Source severity, S, measures the potential health effect of an
emission species at its maximum ground level concentration and
is expressed as the following ratios:
S = (1)
where x = the time-averaged maximum ground level concentra-
max tion for each emission specie
F = hazard factor = ambient air quality standard
(AAQS) for criteria pollutants (particulates,
hydrocarbons, NOX, SOX, and CO) and TLV(8/24)
(1/100) a for noncriteria pollutants
a
8/24 = correction factor to adjust the TLV to a 24-hr exposure
level.
1/100 = safety factor.
62
-------
The values of X were computed from the equation suggested by
Turner (52): ax
xmax xmax It
where Xmax is the "instantaneous" (i.e., 3-min average) maximum
ground level concentration as determined for class C stability
from the equation:
xmax = ireuH2 (3)
where Q = emission rate, g/s
H = emission height, m
TT = 3.14
e = 2.72
u = wind speed, m/s
=4.5 m/s (national average)
t = 3 min
t = averaging time, min
Detailed derivations of the severity equations are presented in
Appendix E.
Tables 28 (53) and 29 (54) list the ambient air quality standards
used for criteria pollutants and the TLV's used for noncriteria
pollutants. Emission factors used for the severity calculations
were those presented in Table 14. Severities were determined for
the three average source types described in Section 3; results
are presented in Table 30. Only POM emissions had severities in
excess of 0.05.
(52) Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
Public Health Service Publication 999-AP-26, U.S. Department
of Health, Education, and Welfare, Cincinnati, Ohio,
May 1970. 84 pp.
(53) Code of Federal Regulations, Title 42 - Public Health,
Chapter IV - Environmental Protection Agency, Part 410 -
National Primary and Secondary Ambient Air Quality Stand-
ards, April 28, 1971. 16 pp.
(54) TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. 94 pp.
63
-------
TABLE 28. AMBIENT AIR QUALITY STANDARDS
FOR CRITERIA POLLUTANTS (53)
Ambient air quality
Emission
Particulate
NOX
sox
CO
standard, mg/m3
0.260
0.100
0.365
40.0
Hydrocarbons 0.160
There is no primary ambient air
quality standard for hydrocarbons.
The value of 160 yg/m3 used for
hydrocarbons in this report is a
recommended guideline for meeting
the primary ambient air quality
standard for oxidants.
Because residential combustion of coal is usually scattered
sparsely throughout the population or in rural locations,
severity for a single emission point adequately represent pre-
sent residential coal combustion. However, it is known that, at
least in isolated areas, groups of residential structures are
or will be equipped with coal-fired heating equipment (12, 55).
The environmental effects from such multiple sources will be
greater than from single sources because of the potential for
plume overlap to increase the ground level concentration in
densely populated areas (55).
A modification of the dispersion model used for single point
severity has been employed to predict the maximum ground level
concentrations of emissions from an array of 100 houses equipped
(55) Cart, E. N., Jr., M. H. Farmer, C. E. Jahnig, M. Lieberman,
and F. M. Spooner. Evaluation of the Feasibility for Wide-
spread Introduction of Coal into the Residential and
Commercial Sectors — Volume I - Executive Summary.
Council of Environmental Quality, Washington, D.C., August
1977. 32 pp.
64
-------
TABLE 29. THRESHOLD LIMIT VALUES USED FOR
NONCRITERIA POLLUTANTS (54)
Emission species
POM (carcinogenic)
Polychlorinated
biphenyls
Elements :
Aluminum
Arsenic
Antimony
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
TLV,
mg/m3
0.001
0.5
10
0.5
0.5
0.5
0.002
10
10
0.7
0.05
5
7.0
0.1
0.1
1
2
10
5
0.15
10
10
5
0.05
5
0.1
0.5
1
2
10
0.2
10
0.01
2
10
0.1
0.1
0.2
10
10
0.2
0.5
10
1
5
5
Compound used for TLV
Carcinogen9
Chlorodiphenyl (54% chlorine) - skin
Alundum, A12O3
Arsenic and compounds
Antimony and compounds
Barium (soluble compounds)
Beryllium
-b
Boron oxide
Bromine
Cadmium oxide fume
Calcium oxide
Hydrogen chloride
Chromic acid and chromates
Cobalt metal, dust, and fume
Copper, dusts, and mists
Fluorine
-b.
Iron oxide fume
Lead, inorganic fumes, and dusts
-b
Magnesium oxide fume
Manganese and compounds
All forms except alkyl
Soluble compounds
Soluble compounds
VanadiumC
Phosphoric acid
Potassium hydroxide
-b
Selenium compounds
Silicon
Metal and soluble compounds
Sodium hydroxide
_b
Tellurium
Thallium soluble compounds
Uranium0
Tin oxide
Titanium dioxide
Soluble and insoluble compounds
Vanadium pentoxide dust, V20s
_b
Yttrium
Zinc oxide fume
Zirconium compounds
Value for carcinogenic compounds corresponds approximately to
the minimum detectable limit; all POM compounds may not be
carcinogenic.
For elements not having an approximate TLV, the TLV for
nuisance particulate, 10 mg/in5, was used.
No TLV found for emission species; used TLV of closely related
compound based on toxicity.
65
-------
TABLE 30. SOURCE SEVERITIES FOR EMISSIONS
FROM AVERAGE, AUTOMATIC, COAL-
FIRED RESIDENTIAL COMBUSTION UNITS9
Emission species
Particulates
SOX
NOX
Hydrocarbons
CO
Polycyclic organic materials
Pol/chlorinated biphenyls
Formaldehyde
Elements:
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
.Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Source severity
Bituminous
3.0 x lO-3
2.0 x 10~2
9.0 x ID"3
2.0 x 10~3
7.0 x 10-=
2.6
<4.5 x 10~7
2.0 x 10-=
7.0 x 10~3
7.0 x 10~a
2.0 x 10-3
9.0 x 10-"
5.0 x 10-3
5.0 x 10-°
1.0 x 10-=
7.0 x 10-*
5.0 x 10-*
1.0 x 10-3
5.0 x 10~3
9.0 x 10-*
3.0 x 10-*
1.0 x 10-*
2.0 x 10-3
2.0 x 10-=
2.0 x 10~2
3.0 x lO-3
1.0 x 10~s
3.0 x 10-*
6.0 x 10-*
2.0 x 10-*
2.0 x 10-=
7.0 x 10~*
2.0 x 10-°
4.0 x 10-*
5.0 x 10~3
2.0 x 10-°
8.0 x 10-*
1.0 x 10~a
5.0 x 10~5
7.0 x 10-*
5.0 x 10-»
5.0 x 10~8
3.0 x 10~s
2.0 x 10-°
9.0 x 10-7
4.0 x 10-*
2.0 x 10-»
2.0 x 10~*
5.0 x 10-'
5.0 x 10~B
1.0 x 10-*
5.0 x 10-8
Anthracite
7.0 x 10-*
4.0 x 1C-3
2.0 x 10~3
2.0 x 10~3
. 5.0 x 10-=
5.0 x 10-a
1.0 x 10~2
7.0 x 10-=
4.0 x 10-*
1.0 x 10-3
5.0 x 10-3
5.0 x 10-8
5.0 x 10-=
7.0 x 10-=
7.0 x 10-*
1.3 x 10-2
1.0 x 10-3
1.0 x lO-3
3.0 x 10~*
1.0 x 10-*
2.0 x 10~3
3.0 x 10~8
4.0 x lO-3
2.0 x ID"3
2.0 x 10~s
3.0 x 10-*
2.0 x 10-s
2.0 x ID"3
1.0 x 10-'
1.0 x 10"3
1.0 x 10-°
4.0 x 10-*
6.0 x ID"3
2.0 x 10~8
7.0 x 10-*
1.0 x 10~a
5.0 x 10~3
1.0 x ID'3
5.0 x 10-=
3.0 x 10-=
2.0 x lO-3
1.0 X 10-«
5.0 x 10~7
7.0 X 10-*
5.0 x ID'8
2.0 x 10-*
5.0 x 10-7
5.0 x 10-°
1.0 x 10-*
5.0 x lO-8
Lignite
1.0 x 10~a
1.0 x 10~a
1.0 x 10~2
1.0 x ID"3
1.0 x 10-=
3.0 x 10-3
3.0 x 10-»
7.0 x 10-*
6.0 x 10~3
7.0 x 10-*
8.0 x 10-s
1.0 x 10-*
2.0 x 10~2
2.0 x ID"3
1.0 x 10-*
7.0 x 10-=
3.0 x 10-=
9.0 x 10-*
5.0 x 10-«
2.0 x 10-a
1.0 x lO-3
1.0 x 10-8
2.0 x 10~3
7.0 x 10~=
1.0 x 10-*
2.0 x 10~=
1.0 x 10-*
1.0 x 10~8
2.0 x 10~3
7.0 x 10-*
7.0 x 10~7
2.0 x 10-*
6.0 x ID"3
5.0 x ID"3
1.0 x 10~a
2.0 x 10-*
3.0 x 10-"
3.0 x 10~7
2.0 x 10-*
2.0 x 10-=
6.0 x 10~5
1.0 x 10~7
2.0 x 10~B
3.0 x 10~s
1.0 x 10-=
Blanks indicate data not available.
Emissions assumed constant over a 24-hr period during the heating
season.
66
-------
with coal-fired heating equipment (56). Figure 12 illustrates
the housing arrangement based on the highest expected concentra-
tion of houses. Determination of ground level concentrations
differs somewhat from that just discussed for single point
sources in that a wind speed of 1.0 m/s and stability class D
were chosen to represent atmospheric conditions (versus national
average conditions of 4.5 m/s and class C used in this report).
Ambient concentration profiles for the conditions chosen are pre-
sented in Figure 13 as a normalized isopleth diagram applicable
to all pollutants (56) . The curves are presented as percentages
of the maximum ground level concentrations of the pollutants.
From Figures 12 and 13, it can be seen that maximum concentration
occurs at about 0.1 km downwind of the residential sources. Most
of the 100 sources contribute to the maximum concentration, al-
though the greatest contribution is from those sources immediately
upwind. Further, relatively high concentrations occur within the
residential array (56).
0.6 r
o
•t.
0.1
0.0
STREET
i 9.1m
45.7m
27.4m
Figure 12.
0.1 0.375
DISTANCE, km
Housing arrangement for the evaluation of
multiple residential coal-fired sources (56)
(56) Weber, R. C. Impact on Local Air Quality from Coal-Fired
Residential Furnaces. Masters Thesis, University of North
Carolina, Chapel Hill, North Carolina, 1978. 88 pp.
67
-------
o
z
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
WIND SPEED =1.0 m/s
D STABILITY CLASS
WIND DIRECTION:
REPRESENTS HOUSING
ARRAY BOUNDARY
-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
DISTANCE, km
Figure 13.
Isopleth diagram representing ambient concentra-
tion profiles as percent of maximum (56).
The model used in Reference 56 shows a direct proportional
response for mass emission rates if all sources are adjusted
simultaneously. For example, if the mass emission rate is
doubled for all sources, the estimated ambient concentration also
doubles. Therefore, if the mass emission rate and maximum ground
level concentration for a particular pollutant are known, the
following relationship can be used to calculate the maximum
ground level concentration for any pollutant emission rate from
the same array of sources (56):
x • =
Amax,i
*max,o (Qi)/Qo
(4)
68
-------
max, i
where Xm=v ^ = average maximum ground level concentration of
species i, g/m3
average maximum ground level concentration for
known reference species as determined by model/
g/m3
Q. = mass emission rate for species i, g/s
Qg = mass emission rate of reference species, g/s
This relationship can be used to determine the maximum ground
level concentration of pollutants from an array of sources that
differs uniformly from the original array as long as it differs
only in mass emission rate and not in other pertinent parameters
such as stack height. The emission sources used in Reference 56
are identical to the average sources used in this study except
for fuel feed rate and average emission factors. Both of these
parameters affect mass emission rate only and therefore allow
Equation 4 to be used to determine the maximum ground level con-
centration for each average_source type from the pollutant emis-
sion rate and the ratio of Xmax/0/Q0 = 0.0172 from Reference 56.
Once Xmax has been calculated from Equation 4, it can be used in
Equation 1 to calculate the severity for 100 houses burning coal.
Table 31 presents the source severities for multiple residential
sources burning bituminous, anthracite, and lignite coals.
Values are about 30 times higher than the severities for a single
source.-
Affected Population
jn addition to source severity, it is important to know how many
people around an average residential combustion unit are exposed
to high ground-level concentrations. Dispersion equations pre-
that the average ground level concentration (x) varies with
distance (x) away from a source. For elevated sources, x" is
2ero at the source, increases to some maximum value, Xmax' as x
increases, and then falls back to zero as x approaches infinity.
rfherefore, a plot of y/F versus x will have the appearances shown
in Figure 14.
X| X2
DISTANCE FROM SOURCE
Figure 14. Variation of \/F with distance.
69
-------
TABLE 31. SOURCE SEVERITIES FOR COAL-FIRED RESIDENTIAL
COMBUSTION EMISSIONS FROM A MULTIPLE SOURCE
ARRAY3
Emission species
Particulates
SOX
NOX
Hydrocarbons
CO
Polycyclic organic materials
Polychlorinated biphenyls
Formaldehyde
Elements:
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Niobium
Phosphorus
Potassium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Tellurium
Thallium
Thorium
Tin
Titanium
Uranium
Vanadium
Ytterbium
Yttrium
Zinc
Zirconium
Source severity'3
Bituminous
1.1 x 10-1
5.3 x 10-'
1.9 x 10-1
1.3 x 10-1
2.0 x 10~3
9.1 x 10 1
<2.0 x 10-s
5.0 x 10-"
2.5 x 10~1
2.0 x 10~3
6.0 x 10~a
3.0 x 10-a
1.6 x 10~1
2.0 x 10~«
5.0 x 10-*
2.0 x 10-'
2.0 x 10-a
4.0 x 10~a
1.6 x 10-'
3.0 x 10-3
1.0 x 10-a
4.0 x 10~3
6.0 x 10~a
8.0 x 10-"
6.0 x 10-'
1.2 x 10~1
4.0 x 10-"
1.0 x 10-3
2.0 x 10~a
6.0 x 10-3
7.0 x 10-"
2.0 x 10~a
2.0 x 10-»
1.0 x 10~a
1.8 x 10~1
8.0 x 10-»
3.0 x 10~a
4.2 x 10~1
3.0 x 10-3
3.0 x 10~a
2.0 x 10-9
3.0 x 10~3
1.0 x 10-3
4.0 x 10-3
3.0 x 10-°
1.0 x 10-a
8.0 x 10-"
6.0 x 10-
8.0 x 10-
2.0 x 10-
5.0 x 10-
2.0 x 10-
Anthracite
2.0 x 10~a
1.3 x 10-1
5.0 x 10-a
5.0 x 10~a
1.0 x 10-3
1.7
3.4 x 10-1
2.0 x 10-3
2.0 x 10-a
3.0 x 10~a
1.7 x 10-1
2.0 x 10-«
2.0 x 10-"
2.0 x ID'3
8.0 x 10-3
2.0 x 10~a
3.7 x 10-1
3.0 x 10-a
1.0 x 10~a
5.0 x 10-3
5.0 x 10-a
9.0 x 10-"
1.5 x 10-1
9.0 x 10~a
6.0 x 10-"
1.0 x 10-3
7.0 x 10-"
7.0 x 10-3
5.0 x 10-"
3.0 x 10~a
1.0 x 10-3
1.0 x 10~a
2.1 x 10-1
9.0 x 10-=
3.0 x 10~a
4.6 x 10-1
2.5 x 10-1
4.0 x 10~a
2.0 x 10-a
1.0 x 10~3
6.0 x 10~a
3.0 x 10~3
2.0 x 10-°
3.0 x 10~a
2.0 x 10-»
7.0 x 10~3
2.0 x 10-B
2.0 x 10-»
4.0 x 10~3
2.0 x 10-»
Lignite
4.1 x 10-1
5.0 x 10~1
2.4 x 10-i
3.0 x 10~a
2.0 x 10-*
9.0 x 10-a
1.0 x 10~3
3.0 x 10-a
1.9 x 10-i
2.0 x 10~a
3.0 x 10-3
4.0 x 10~3
5.8 x 10-i
6.0 x 10~a
5.0 x 10~3
2.0 x 10-3
1.0 x 10~3
3.0 x 10~a
2.0 x 10-*
6.3 x 10-1
4.0 x 10~a
5.0 x 10~s
8.0 x 10-3
2.0 x 10-3
5.0 x 10-3
7.0 x 10-*
5.0 x 10~3
1.0 x 10-»
8.0 x 10~a
2.0 x 10~a
2.0 x 10-"
7.0 x 10-3
2.1 x 10~1
2.5 x 10-1
4.4 x 10~1
8.0 x 10-3
5.0 x 10-3
1.0 x 10-»
8.0 x 10-3
9.0 x 10-"
2.0 x 10~3
5.0 x 10-»
7.0 x 10-"
1.0 x 10~3
5.0 x 10-"
Emissions assumed constant over a 24-hr period during the
heating season. '
70
-------
The affected population is defined as the population living in
the area around a representative source where y/F is greater than
0-05 or 1.0. The mathematical derivation of the affected popula-
tion can be found in Appendix E. The affected population for
coal-fired residential combustion emissions from a single source
is presented in Table 32 and was determined from the population
density for the average sources described in Section 3.
TABLE 32. AFFECTED POPULATION FOR SINGLE SOURCE EMISSIONS
(Number of persons)
BituminousAnthraciteLignite
missions species8 x/F > 0.05 x/F > 1.0 X/F > 0.05 x/F > 1.0 x/F > 0-05 x/F > 1.0
Polycyclic organic
materials 115 5 3 0 0 0
Only species with affected populations greater than zero are listed.
Like source severity, the population affected by multiple residen-
tial coal combustion sources is much greater than that affected
ky a single source. Maximum ground-level concentrations of a
specific pollutant will be higher for multiple sources. Conse-
quently, the area of land and affected population covered by a
ground-level concentration corresponding to a specified x/F is
much greater for multiple sources.
Although the model for single source affected population cannot
j-,6 applied to multiple sources, the affected population can be
predicted from the concentration isopleth diagram (Figure 13) and
the maximum ground-level concentration of each pollutant. The
affected population is those persons who live in an area around
tjie source where x/F i£ >1.0 or >0.05. Because F is known for a
particular pollutant, x"/ the average ground-level concentration,
can be calculated for each condition of x/F. But the isopleth
diagram expresses ground-level concentrations in terms of percent
of maximum ground-level concentration. Therefore, dividing "x by
XfliaX' as determined from the calculation of severity for multiple
0ources, gives limits of the downwind distance where X/F >1.0 or
?0.05 in terms of percent of maximum ground level concentration.
•These limits correspond to a distance in kilometers on the Y axis
Of the isopleth diagram and can be used to calculate XT and xa,
Distance from the center of the housing array.
geveral simplifying assumptions had to be made at this point:
1. The housing array was treated as a single source with
the emission point in its center.
2. When x, fell within the array of houses, it was assigned
the value corresponding to the outermost distance of the
array.
71
-------
3. The population density around the array of houses was
chosen to be the average population density for stand-
ard metropolitan statistical areas/ or 139 persons/km2
(57).
With these assumption, xi and x2 define the area of land around
a housing array affected by ground level concentrations of a
pollutant where x/F >1.0 and 0.05. The affected population can
then be determined using the population density of 139 persons/
km2.
Table 33 presents the affected population for coal-fired residen-
tial combustion emissions generated by multiple sources. Because
of assumption 2, described above, these numbers exclude the
population of the housing array. Most of the housing array act-
ually falls within the affected areas; therefore, the population
of the array should also be considered. Assuming an average of
2.9 persons per household (57), 2,900 persons within the housing
array would also be affected. Comparing this to Table 32, it can
be seen that for many pollutants the population within the array
is that most affected due to the low stack heights. For others,
such as POM's, the area affected by the designated hazardous
concentration extends beyond the bounds of this model correspond-
ing to the 1% isopleth in Figure 13.
State and National Emission Burden
Another measure of the potential impact on the environment is the
total annual emissions of each criteria pollutant. Estimated
annual emissions from coal-fired residential combustion equipment
on a state-by-state basis are derived and tabulated in Appendix F.
These were calculated using emission factors and fuel usage
estimates. The appendix also shows the percent contribution of
each source type to the total state emission burden from all
stationary sources.
The tables in Appendix D show that in 1974 residential combus-
tion of bituminous coal had the greatest impact on emissions on
a state-by-state basis, exceeding 1% of the total state SOX
emissions in the District of Columbia, Virginia, and West
Virginia.
Total national criteria emissions from each source with corre-
sponding national emission burdens are given in Table 34.
(57) Statistical Abstracts of the United States 1975. U.S,
Department of Commerce, Washington, D.C., July 1975.
1050 pp.
72
-------
TABLE 33. POPULATION AFFECTED BY EMISSIONS
FROM MULTIPLE SOURCES
(Number of persons)
Bituminous
Emissions species
Particulate
SOX
NOx
HC
POM
Elements :
Aluminum
Arsenic
Barium
Beryllium
Calcium
Chlorine
Fluorine
Iron
Lead
Magnesium
Phosphorus
Potassium
Silicon
Silver
Sodium
Thallium
X/F > 0.05
585
4,361
1.593
783
>5,000D
2,537
98
0
1,174
0
1,174
98
4,930
714
0
0
1,353
3,826
0
0
0
X/F > 1.0
0
0
0
0
>5,000b
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Anthracite
X/F > 0.05
0
783
0
o.
>5,000D
3,326
0
0
1,218
0
3,473
0
1,035
394
0
0
1,853
3,852
2,537
0
98
X/F > 1.0
0
0
0
0
352
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Lignite
X/F > 0.05
3,826
>5,000b
2,403
0
0
394
0
1,560
0
4,766
97
o.
>5,000D
0
296
296
0
1,853
2,537
4,089
0
X/F > 1.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Only species with affected population greater than zero are listed.
b
Actual number could not be determined because of the limits of the isopleth diagram in
Figure 13.
TABLE 34. ESTIMATED ANNUAL CRITERIA EMISSIONS AND
BURDEN FROM COAL-FIRED RESIDENTIAL
COMBUSTION FOR 1974
Emission '
species
particulate
SOx
JJOX
Hydrocarbons
CO
rotal annual emissions, metric tons/yr
Bituminous
14,425
66,104
5,210
5,376
58,032
Anthracite
937
6,916
769
1,110
7,089
Lignite
244
423
56
9
19
National emission burden,
total of all stationary
Bituminous
0.08
0.2
0.02
0.02
0.05
Anthracite
<0.01
0.02
<0.01
<0.01
0.01
percent of
sources
Lignite
<0.01
<0.01
<0.01
<0.01
<0.01
73
-------
A comparison of the national emissions of criteria pollutants from
coal-fired residential combustion to other forms of residential
combustion (Table 35) shows that coal combustion contributes
between 2%' and 30% of the total from the residential sector.
TABLE 35. TOTAL ANNUAL EMISSIONS OF CRITERIA POLLUTANTS
FROM RESIDENTIAL COMBUSTION SOURCES3
Fuel type
Emissions, metric tons/yr
Particulates
SOx
NOx
Hydrocarbons
CO
Utility, bottled, tank
or L.P. gas (2)
Fuel oil, kerosene,
47,000
1,400 191,000 19,000
49,000
etc. (2)
Coal
Wood (2)
74,000
15,606
23,000
1,090,000
73,443
3,400
89,000
6,035
23,000
23,000
6,495
4,500
37,000
65,140
4,500
Coal emissions were determined in this report; others are from Reference 2.
Annual national emissions of POM from automatic, coal-fired,
residential combustion units are about 101 metric tons from
bituminous coal-firing and 0.9 metric tons from anthracite coal-
firing. A study conducted in 1967 estimated the total annual
POM emissions from residential coal combustion to be about
372 metric tons or 85% of all POM emissions nationally (39). A
more recent survey found these emissions to be 243 metric tons
annually, but in this case, that represented only 3.4% of all
POM emissions nationally, The survey showed that POM emissions
from coal refuse piles account for 82% and those from coke
manufacturing account for 9% of the national total POM emissions
(58). The earlier study did not list coal refuse piles and
considered POM emissions from coke manufacturing as negligible.
A study of coal refuse pile emissions presents a POM emission
rate of about 1.3 x 10~8 kg/hr per metric ton of burning refuse
and an estimated 250 x 106 metric tons of refuse in 1968 (59).
This yields a total annual POM emission that is about two orders
(58) Eimutis, E. C., R. P. Quill, and G. M. Rinaldi. Source
Assessment: Noncriteria Pollutant Emissions (1978 Update).
EPA 600/2-78-004t, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, July 1978. 149 pp.
(59) Chalekode, P. K., and T. R. Blackwood. Source Assessment:
Coal Refuse Piles, Abandoned Mines and Outcrops, State-of-
the-Art. EPA 600/2-78-004v, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, July 1978.
51 pp.
74
-------
of magnitude lower than that in the recent survey. At this rate,
the annual POM emissions from residential coal combustion are
about 10% of the national total. Although this number is uncer-
tain, it does indicate that increased residential coal combustion
may have a significant impact on POM emissions nationally and may
have an even greater impact on state and local POM emission
levels.
75
-------
SECTION 5
CONTROL TECHNOLOGY
Because of the past decline of coal-fired residential heating
systems, there has been little interest in controlling emissions
from these sources. No add-on emission control devices are
currently on the market; however, any improvement in combustion
efficiency will usually result in some improvement of emission
levels. Two studies of emissions from coal-fired equipment in
the residential size range have recently been completed (6, 15).
Although no definite conclusions can be reached, the results
indicate several possibilities. The condition of the fuel bed is
important in reducing emissions, such as particulates and POM's,
since a poor fuel bed can result in incomplete combustion. Fuel
bed conditions can be improved by burning coals such as anthra-
cite or western subbituminous coal which have low caking prop-
erties. Coals containing excessive fines can interefere with the
uniform distribution of combustion air and contribute entrained
particles to the flue gas.
Coal properties also affect emission levels. Burning a coal with
low volatile content such as anthracite or low volatile bitumin-
ous will result in lower particulate and POM emissions than
burning coals with high volatile content. Western coals with
high lime content in the ash may have a smaller fraction of their
sulfur content emitted due to reaction with the lime during
combustion (6, 15, 22).
Experiments with overfire air during combustion indicate that
visible emissions from coals with volatile contents of over 20%
by weight are eliminated with overfire air. However, the visible
emissions reduction did not significantly affect particulate
emissions levels (6).
Concentrations of particulate, POM's, and carbon monoxide leaving
the combustion chamber have been found to be highest from the OFF
segment of the heating cycle during tests burning high volatile
bituminous coal. It was observed that residential bituminous
stokers operate at one speed with the combustion air fan and the
feed screw running concurrently. This results in excessive
amounts of air during the initial ON segment and a deficiency in
combustion air during the initial OFF period (6, 15).
76
-------
In the combustion of high volatile bituminous coals, modification
of this cycle to achieve a better control of combustion air
during these periods resulted in a reduction of POM and particu-
late emissions. The modification had no effect on emissions from
the combustion of western subbituminous coal (6).
processed smokeless coals were suggested (6) for reducing partic-
ulates and POM emissions. However, the one test that was con-
ducted proved inconclusive, since the processed coal (lignite
char) was soft and broke into fine particles, resulting in a
high particulate loading.
in general, it was concluded that emissions from stoker-fired
boilers can be reduced by providing overfire air and proper
control of combustion (a modified cycle). In addition, proper
choice of coals (anthracite, western subbituminous and processed
coals) can reduce emissions (6). However, these coals are either
in limited supply or are not located near the largest potential
market.
•
One report proposed that all clean fuels such as low sulfur coal
£e allocated to the residential sector since add-on control tech-
nology would be financially impossible for most consumers (60).
However, the problem of high coal transportation costs from the
mine to the market area remains, because the cleaner coals are
located far from the largest potential markets.
£, study was performed to evaluate emission reduction techniques
in oil- and gas-fired residential furnaces (61), which, in some
areas, can apply to coal-fired units. Table 36 summarizes those
control strategies that may apply to coal-fired equipment. A
major problem of burning coal in the residential sector is the
caking properties of bituminous coals (6). One research effort
Demonstrated that the caking properties of coal (free swelling in-
£ex) can be destroyed by reacting the coal with boron trifluoride
(62). Table 37 shows the results of this study and indicates
(60) Hall, E. H., P. S. K. Choi, and E. L. iKropp. Assessment of
the Potential of Clean Fuels and Energy Technology.
EPA 600/2-74-001 (PB 239 970), U.S. Environmental Protection
Agency, Washington, D.C., February 1974. 193 pp.
(6l) Brown, R. A., C. B. Moyer, and R. J. Schreiber. Feasibility
of a Heat and Emission Loss Prevention System for Area
Source Furnaces. EPA-600/2-76-097 (PB 253 945), U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, April 1976. 187 pp.
(62) Chakrabartty, S. K., and N. Berkowitz. Properties of Caking
Coals: Destruction of Caking Properties by Boron
Trifluoride. Fuel, 51{l):44-46, 1972.
77
-------
TABLE 36. COMBUSTION CONTROL STRATEGIES FOR
REDUCING AIR POLLUTANTS FROM
RESIDENTIAL HEATING EQUIPMENT (61)
Control strategy
Impacted
pollutant emission
Comments
Excess air level
Combustion
chamber design
Service and
maintenance
NOX
CO
Hydrocarbons
Smoke/particulate
CO
Hydrocarbons
Smoke/particulate
As excess air is increased, CO, HC, and
smoke pass through a minimum, but NOX
passes through a maximum
Optimum pollutant and thermal efficiency
level occurs at a stoichiometric ratio
greater than one
Combustion chamber design affording long
residence time at high temperature
minimizes smoke, particulates, CO, HC,
but may increase NOX
Refractory-lined chamber affords better
combustion and lower emissions
Equipment state-of-repair very important
for providing breadth for reducing
emissions by other methods
Air filter should be replaced regularly
TABLE 37. EFFECT OF BORON TRIFLUORIDE ON FREE SWELLING
INDEX AND VOLATILE MATTER OF HIGH VOLATILE
BITUMINOUS COALS. (62)
Coal
No. 1
No. 2
Parameter Initial
Free swelling index
Percent volatile matter,
by wt
Free swelling index
Percent volatile matter.
by wt
6.5
30.6
4
29.1
Nitrogen/boron trifluoride
at temperature shown
25°C 50°C 100«C 150°C 200°C 250»C
000000
26.5 26.8 27.2 27.2 26.7 27.7
1.5 1 1 1 0.5 0
26.1
Note.—Blanks indicate no data reported in reference cited.
that caking properties can be destroyed at temperatures as low as
25°C without significant change in volatile content. The cost of
this process was not discussed, and therefore its viability in
the residential coal market is unknown.
Emissions studies have not been conducted with this coal and it
is not known what effect the boron trifluoride will have on other
emissions or on equipment corrosion.
78
-------
SECTION 6
GROWTH AND NATURE OF THE SOURCE
Before the twentieth century, coal and wood were the predominant
fuels available for residential heating in the United States.
Near the turn of the century gas and oil entered the home heating
market. However, these fuels were only available to a small
number of homes near the source. Developments around 1920 made
it possible to deliver large quantities of these fuels to distant
markets and signaled the decline of coal and wood use for home
heating. Coal was still a major home heating fuel in 1940, when
19,000,000 occupied housing units burned it for primary heating
purposes (57). This was about 54% of the total number of
occupied housing units in the United States. From that point,
however, the decline was rapid. By 1970, housing units burning
coal for heat numbered about 1,800,000 units (5), accounting for
less than 3% of the total number of occupied housing units. By
1974, coal-fired heating declined to 740,000 housing units, a 60%
drop from 1970 (1). Figure 15 shows the decline of coal-fired
residential heating.
a
o_
3
HOUSING UNITS WITH COAL HEATING
1960
1970 1974
YEAR
Figure 15,
Residential coal-firing
heating trends (57).
79
-------
Most recent figures on the population of coal-fired heating
devices are not available. However, most manufacturers agree
that there is increased interest in this type of home heating,
although not all manufacturers are seeing a corresponding increase
in sales (18, 63, 64).
In spite of high heating bills, most people are not willing to
rely on coal for heat. Statistics on the shipments of solid fuel
heating equipment indicate a sudden demand for stove type heating
devices, starting around 1973. In 1972, total solid fuel residen-
tial heating equipment shipped was about 229,000 units (65). In
1975, the number jumped to about 605,000 units. Of these, 254
were stokers, and 2,233 were forced-air furnaces. The remainder
were domestic heating stoves (66, 67). Stokers have not yet
increased in sales, but sales of warm-air furnaces increased 450%
from 1972 to 1976 (65-68). Approximately 75% of the heating
stoves shipped in 1976 were classified as coal and wood burners.
Figure 16 shows the trends in shipments of solid fuel residential
heating devices (65-76). Modern coal-fired warm-air furnaces are
designed to be more appealing to today's homeowners. Sales have
been limited to the West, because these units are designed to
burn subbituminous coal most effectively. One manufacturer
claims that a large potential market exists in the East for coal-
fired warm-air furnaces capable of burning bituminous coal (63).
600.000
30.000
1980
Figure 16.
Shipments of coal- and wood-fired
residential heating devices (65-76)
(63) Personal communication with B. Prill, Prill Manufacturing
Corporation, Sheridan, Wyoming, 7 December 1976.
(64) Personal communication with James E. Axeman, Axeman -
Anderson Company, Williamsport, Pennsylvania, 6 October 1977.
(continued)
80
-------
There are conflicting opinions as to whether residential coal
combustion is on the increase and, if so, whether the increase
will be significant enough to cause environmental problems. Part
of the conflict may be the result of regional trends. Recently
released estimates of housing units heating with coal in 1975
showed a 50% increase in the West while the remainder of the
country exhibited a 25% decline (77). The interest in coal
heating is so strong in Colorado that contractors are building
homes with the option of coal heating. As a result, the Colorado
Department of Health was forced to institute a permit program
for residential coal heating devices (78).
(continued)
(65) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, MA-34N(72)-1, U.S. Department of
Commerce, Washington, D.C., November 1973. 9 pp.
(66) Current Industrial Reports, Selected Heating Equipment.
Bureau of the Census, MA-34N(75)-1, U.S. Department of Com-
merce, Washington, D.C., July 1976. 6 pp.
(67) Current Industrial Reports, Air Conditioning and Refrigera-
tion Equipment Including Warm Air Furnaces. Bureau of the
Census, MA-35M975)-!, U.S. Department of Commerce,
Washington, D.C., October 1976. 14 pp.
(68) Current Industrial Reports, Air Conditioning and Refrigera-
tion Equipment Including Warm Air Furnaces. Bureau of the
Census, MA-35M(76)-1, U.S. Department of Commerce,
Washington, D.C., July 1977. 14 pp.
(69) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, M34N(60)-13, U.S. Department of
Commerce, Washington, D.C., August 1961. 7 pp.
(70) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, M34N(64)-13, U.S. Department of Com-
merce, Washington, D.C., July 1966. 9 pp.
(71) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, M34N(65)-13, U.S. Department of Com-
merce, Washington, D.C., January 1967. 9 pp.
(72) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, M34N(66)-13, U.S. Department of Com-
merce, Washington, D.C., February 1968. 9 pp.
(73) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, M34N(67)-13, U.S. Department of Com-
merce, Washington, D.C., January 1969. 7 pp.
(74) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, M34N(69)-13, U.S. Department of Com-
merce, Washington, D.C., February 1971. 7 pp.
(continued)
81
-------
A recent study on the feasibility of introducing coal into the
residential sector led to the following conclusions related to
its potential growth (55):
1. Direct use of coal in cities and large residential
areas will result in severe environmental problems.
2. Emissions of particulates, SOz, NOX, hydrocarbons,
and CO will be much greater from coal-fired residential
combustion than from gas- or oil-fired furnaces.
3. Significant social and institutional problems will
need to be overcome.
4. People will resist the inconvenience of handling and
storing coal, and ash disposal.
5. Problems will be encountered in reestablishing a retail
coal distribution system, especially without the
existence of an established market.
6. On a total cost basis, the economics of increased
residential coal combustion appears to be generally
unfavorable.
7. Renewed interest in coal-fired furnaces in the Mountain
and the West North Central regions is likely to have
little impact on the total energy demand in the
residential sector.
Although national trends remain difficult to predict, it is
obvious that coal heating is increasing in certain parts of the
country. The future of coal heating will depend on equipment and
fuel availability, comparative costs of other fuels, and the
impact of governmental emission regulations.
(continued)
(75) Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, M34N(70)-13, U.S. Department of Com-
merce, Washington, D.C., December 1971. 9 pp.
(76) Current Industrial Reports, Selected Heating Equipment.
Bureau of the Census, MA34N(76)-1, U.S. Department of Com-
merce, Washington, D.C., August 1977. 7 pp.
(77) Current Housing Reports, Bureau of the Census Final Report
H-150-75; Annual Housing Survey: 1975, Part A; General
Housing Characteristics for the United States and Regions.
U.S. Department of Commerce, Washington, D.C., April 1977.
270 pp.
(78) Personal communication with J. Scott Kinsey, Colorado
Department of Health, Denver, Colorado, 14 March 1977.
82
-------
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83
-------
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84
-------
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41. Briggs, D. Testing of Particulate and Sulfur Oxide Emissions
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88
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62. Chakrabartty, S. K., and N. Berkowitz. Properties of Caking
Coals: Destruction of Caking Properties by Boron
Trifluoride. Fuel, 51(l):44-46, 1972.
63. Personal communication with B. Prill, Prill Manufacturing
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64. Personal communication with James E. Axeman, Axeman -
Anderson Company, Williamsport, Pennsylvania, 6 October 1977
65. Current Industrial Reports, Heating and Cooking Equipment.
Bureau of the Census, MA-34N(72)-1, U.S. Department of
Commerce, Washington, D.C., November 1973. 9 pp.
66. Current Industrial Reports, Selected Heating Equipment.
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Washington, D.C., October 1976. 14 pp.
58. Current Industrial Reports, Air Conditioning and Refrigera-
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Commerce, Washington, D.C., August 1961. 7 pp.
70. Current Industrial Reports, Heating and Cooking Equipment.
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89
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H-150-75; Annual Housing Survey: 1975, Part A; General
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90
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APPENDIX A
DETERMINATION OP REPRESENTATIVE SOURCES
FUEL FEED RATE DETERMINATION FOR A REPRESENTATIVE SOURCE
Because a representative source is defined by average conditions,
the fuel feed rate of the source is based on the average heat
load of each source. This average heat load is computed by
weighting the average number of heating degree-days of each state
(60) where the source is located by the number of housing units
Burning that fuel in each state. Therefore,
Weighted average of heating degree-days for a source
(Degree-days) . (housing units burning coal type) .
_ i _ , _ , _ _ i. (A-l)
U.S. total housing units burning coal type
i=l
where i = each state
A-l lists the average heating degree-days for each state
for a 30-year period from 1941 to 1970.
fuel usage is then determined by the amount of fuel needed
per degree-day per dwelling unit which Reference 34 gives as
J.I kg/degree-day per dwelling unit for coal. Assuming that the
jjulk °f tne heating season for bituminous and anthracite coal is
about 212 days (October 1 to April 30) and that for lignite com-
^ustion in North Dakota is 243 days (September 15 to May 15) , the
average hourly feed rate of a representative combustion unit can
^e determined. For residential combustion of bituminous, anthra-
cite, and lignite coals the average hourly feed rates were deter-
to be 1.1 kg/hr, 1.2 kg/hr, and 1.7 kg/hr, respectively.
pgTERMINATION OF REPRESENTATIVE SOURCE EMISSION HEIGHT
£jnission heights of residential combustion equipment will vary
with building height and placement within a buidling. The mini-
UIn recommended chimney height for coal-fired residential units
10.7 m above the stoker feet, 6.1 m to 7.6 m above the boiler
stoker-fired units, and 8.5 m to 9.8 m above the boiler for
91
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TABLE A-l.
ANNUAL HEATING DEGREE-DAYS AND HOUSING
UNITS BURNING COAL FOR ALL STATES
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Dist. Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Total
Degree days
1,684
9,007
1,552
3,354
2,331
6,016
6,350
4;940
4,211
767
3,095
0
5,833
6,113
5,577
6,710
4,687
4,640
1,465
7,498
4,729
5,621
7,086
9,034
2,300
4,956
7,652
6,049
6,022
7,360
4,946
4,292
6,221
3,366
9,044
5,642
3,695
4,792
5.398
5,972
2,598
7,838
3,462
2,134
5,983
7,876
3,714
6,010
4,590
7,444
7,255
_c
Number of housing units in 1974a
Bituminous
20,384
779
92
971
286
3,427
0
0
3,333
183
9,412
34
5,114
28,389
4.771
1,421
174
51,321
22
0
0
575
4,773
1,782
2,002
1,406
1,125
272
175
0
0
248
357
16,207
0
9,923
165
613
40,625
0
8,842
309
47,885
134
4,464
0
35,426
2,991
29,926
3,227
875
346,940
Anthracite
0
0
0
0
0
0
776
645
461
0
0
0
0
595
1,165
0
0
0
0
795
8,131
1,976
1,637
0
0
0
0
0
0
461
10,211
0
28,391
0
0
1,074
0
0
103,742
137
0
0
0
0
0
768
0
0
0
0
0
160,965
Lignite
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1,028
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1,028
Values are derived in Appendix B from data in References 1 and 31.
Data in Reference 57 are given for major cities in each state.
For this study, it was assumed that these numbers approximated
state averages.
CNot applicable.
92
-------
hand-fired units (9, 79). Assuming all units are located in a
basement approximately 3 m below ground level, the emission
height is taken to be 6.1 m above ground.
AVERAGE POPULATION DENSITY OF A REPRESENTATIVE SOURCE
To determine the affected population for a pollutant from an
emission source, the population density around the source must be
known. For sources such as coal-fired residential combustion
equipment/ the associated population density can best be repre-
sented by a weighted average population density for each state
where that source is located. This can be represented by the
expression:
Weighted average population density for all states
50
__ (Population density) . (housing units burning coal type).
• _-, U.S. total housing units burning coal type
1-1 (A-2)
where i = each state
Table A-2 lists the population densities for each state for 1974.
in the case of lignite combustion, a weighted average was not
needed because it is assumed all lignite-fired residential com-
bustion takes place in North Dakota.
DETERMINATION OF A TYPICAL BURNING CYCLE FOR AUTOMATIC COAL-
FIRED EQUIPMENT
The typical burning cycle represents the operation of an auto-
matic coal-fired residential heating system located in an area
and at a time of year with an average heat demand. Using Equa-
tion A-l for all coal gives a weighted average heat load of
4,809 degree-days.
Assuming that the typical residential housing unit has a furnace
Of about 105-MJ/hr output operated at about 75% load and burning
a coal with 26.7-MJ/kg heating value, the furnace feed rate can
calculated as follows:
/79) Technical Manual on Industry Standards, Recommended Prac-
tices and Technical Information, Second Edition. Stoker
Manufacturers,1 Association, Chicago, Illinois, 1947.
93
-------
TABLE A-2. STATE POPULATION DENSITIES FOR 1974 (57)
State
Population
density,
persons/km2
State
Population
density,
persons/km2
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Dist. Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
27
0.2
7.3
15
52
4.3
245
112
4,575
58
32
51
3.7
77
57
20
11
33
32
13
160
286
62
19
19
27
Montana 1.9
Nebraska 7.7
Nevada 2.0
New Hampshire 35
New Jersey 376
New Mexico 3.6
New York 146
North Carolina 42
North Dakota 3.6
Ohio 101
Oklahoma 15
Oregon 9.3
Pennsylvania 102
Rhode Island 345
South Carolina 36
South Dakota 3.5
Tennessee 39
Texas 18
Utah 5.4
Vermont 20
Virginia 47
Washington 20
West Virginia 29
Wisconsin 32
Wyoming 1.4
105 MJ/hr x 0.75 , Q
26.7 MJ/kg*y
To determine the length of time the furnace must operate, the
following calculation is performed:
4,809 degree-days/yr x 1.1 kg coal/degree-day
per dwelling unit ^ 5,290 kg/yr of coal
Assume a heating season of 212 days; therefore
5,290 kg/yr T 212 days = 25 kg/day
Furthermore,
25 kg/day f 2.9 kg/hr =8.6 hr/day
94
-------
8.6 hr/day x 60 min/hr or) •„/!„.
t-j—r—-7-5 c = ^<& min/hr
24 hr/day '
when combustion takes place, while for 38 min/hr the fuel bed is
inactive.
95
-------
APPENDIX B
ESTIMATION OF THE SOURCE POPULATION AND FUEL CONSUMPTION
The most recent published data on the population of coal-fired
heating equipment are in the 1974 Annual Housing Survey published
by the U.S. Bureau of Census. However, this report is based on
data collected from a sample population; it lacks the detail
necessary to adequately characterize the whole population. The
1970 Census of Housing surveyed the total population and is much
more detailed than the 1974 Housing Survey. To obtain a better
estimate of the 1974 population this appendix employs certain
relationships and trends observed in various tables from both
surveys.
Table B-l is from the 1970 Census of Housing and shows the number
of housing units burning coal for heat by type of heating equip-
ment. The population of heating equipment cannot be directly
inferred from this table, however, and to determine the popula-
tion of primary coal-fired heating equipment, the following
assumptions are made:
1. Single-unit structures (including mobile homes and trailers)
have one primary heating device.
2. All owner-occupied multiunit structures heating with coal
combustion do not exceed two housing units per structure.
3. Multiunit structures have one primary heating device per
structure;
• for two-unit structures, the number of housing units
is divided by two to estimate the average number of
heating devices;
• for three- and four-unit structures (assuming a normal
distribution),the number of housing units is divided
by 3.5 to estimate the average number of heating devices;
• for 5- to 19-unit structures (assuming a normal distri-
bution) , the number of housing units is divided by 12
to estimate the average number of heating devices; and
96
-------
ID
TABLE B-l. POPULATION OF HOUSING UNITS BURNING COAL FOR HEAT (5)
Housing units, 1970
Owner occupied
Heating equipment
Steam or hot water
Warm-air furnace
Floor, wall, or
pipeless furnace
Other*
•total
1-unit
structures
148,783
404,304
38,682
312,969
904,738
2 units or
more per
structure
34,374
22,592
1,619
6,246
.64,831
Mobile
home or
trailer
136
1,234
336
1,284
2,990
1-unit
structures
38,976
102,571
13,359
233,906
388,812
2-unit
structures
33,406
24,274
2,605
18,588
78,873
Renter occupied
3 & 4
units per
structure
43,621
10,896
1,223
6,802
62,542
5 to 19
units per
structure
148,569
10,488
1,775
3,687
164,519
20 units or
more per
structure
143,135
6,897
1,638
916
152,586
Mobile
home or
trailer
114
392
44
511
1,061
Total
591,114
583,648
61,281
584,909
1,820,952
Fireplaces, stoves, or portable heaters.
-------
• for 20 units or more per structure, the number of
housing units is divided by 20 to estimate the upper
limit of heating equipment for this size structure.
These assumptions transform Table B-l into Table B-2.
TABLE B-2. POPULATION OP COAL-FIRED HEATING EQUIPMENT
Heating equipment
Steam or hot water
Warm-air furnace
Floor, wall, or
pipeless furnace
Other
Total
Estimated
1-unit3
structures
188,009
508,501
52,421
598,670
1,297,601
number of primary heating devices by
2-unit
structures
33,890
24,433
2,113
12,417
71,853
3 & 4-unit
structures
12,463
3,113
349
1,943
17,868
5 to 19-unit
structures
12,381
874
148
307
13,710
structure size, 1970
20 or more
units per
structure
7,157
345
82
46
7,630
Total
253,900
536,266
55,113
563,383
1,408,662
Includes mobile homes and trailers.
b
Fireplaces, stoves, or portable heaters.
Dividing the total number of heating devices by the total number
of housing units establishes the following relationship for use
on the 1974 data:
• 0.774 coal-fired heating device per housing unit
heated by coal.
• 0.752 coal-fired heating device in one- and two-unit
structures per housing unit heated with coal.
The 1970 Census of Housing also presents a state-by-state listing
of housing units heated by coal. The 1974 survey does not give a
state-by-state listing; instead it presents the housing units by
region for 1970 and 1974. From this the percent change was
computed for each region (Table B-3).
The regional percent change in housing units was applied to the
respective states in the 1970 Census to estimate the 1974 state
population of housing units burning coal. The previously estab-
lished relationships of heating devices to housing units were
then applied to these estimates to predict the state population
of heating devices.
The amount and type of coal burned in the residential sector for
each state has been estimated based on the 1970 Census of Housing,
heat demand, and retail coal sales data (32). Dividing the total
fuel usage by the number of housing units from the 1970 census
98
-------
TABLE B-3. REGIONAL DISTRIBUTION OF HOUSING UNITS
HEATING WITH COAL - 1970 and 1974 (1)
Housing units
Year Northeast North central South West
1970
1974
540,702
244,000
574,810
165,000
624,005
306,000
81,435
26,000
Percent change
-55 -86 -51 -68
gives an estimate of the amount of fuel burned per housing unit
in each state. This number applied to the 1974 estimate of
housing units burning coal provides a state-by-state estimate of
fuel usage for 1974. The fuel usage presented in Reference 32 is
for bituminous and anthracite coal. The ratio of bituminous coal
to anthracite coal used in each state for residential heating is
assumed to be the same as the ratio of bituminous coal-fired
equipment to anthracite-fired equipment, establishing the popula-
tion and distribution of these devices.
99
-------
APPENDIX C
DERIVATION OF EMISSION FACTORS
Some calculations in this appendix have been made using nonmetric
units; however, all final emission factors were converted to
metric form in this appendix and in the text.
Source test measurements summarized in Tables C-l through C-7
were used to derive average emission factors as described below.
BITUMINOUS COAL COMBUSTION
Five sources of information were employed to determine emission
factors for residential combustion of bituminous coal. The most
extensive testing was performed as a special project under this
contract. The results of the special project (15) and another
study (30) were presented in nonmetric units and were converted
to metric for this report.
Emissions data on particulate, CO, hydrocarbons, N0£/ S02/ and
formaldehyde as Ib/ton of coal (38) were merely converted to
metric units. For emissions data on POM's as micrograms per
106 Btu heat input (38, 39), the heat input to the system and
the fuel feed rate were used to calculate emission factors, as
in the following example:
1,493,100 yg g 58,000 Btu hr lb
105 Btu * 106 yg x j^x 4>2 ib x 0.454 kg
= 0.045 g of POM/kg coal
Data were also provided (6) for the emission of particulates,
POM, S02, NO, and CO from residential combustion of bituminous
coal. Particulate and POM emissions, presented in grams per
pound and milligrams per pound respectively, can readily be con-
verted to grams per kilogram. However, S02, NO, and CO emissions
were presented as concentrations in the flue gas and listed
separately for the ON and OFF portions of the furnace cycle. The
stack gas volumes were not reported, but the amount of air, in
pounds, fed to the combustion chamber during the ON portion of
the cycle was presented. To determine the stack gas volume dur-
ing the OFF portion of the cycle, it was necessary to back-calcu-
late from the particulate emission factor and particulate loading
for each test run.
100
-------
TABLE C-l.
EMISSION FACTORS FOR POM AND CRITERIA POLLUTANTS FROM COAL-FIRED
RESIDENTIAL HEATING EQUIPMENT OPERATED ON A 20-MIN "ON"/40-MIN
"OFF" HEATING CYCLE9
Coal
rest run
Heating
Ash
Sulfur Excess
k content, content,* air.
number equipoent" Designation %
1,2
3,4
5,6
7,8
9,10
11.12
13,14,15,16
25,26,27,28
17,18,19,20
21,22,23,24
29
Boiler
Boiler
Boiler
Boiler
Boiler
Boiler
Furnace
Furnace
Furnace
Furnace
Furnace
A
A
A
B
B
B
B
B
B
B
C
Most emission factors represent
Both units a
when stoker
CAs received.
re rated
was OH.
d
Front
10.9
7.5
4.3
9.1
7.1
5.0
5.0
7.1
9.1
9.1
3.3
*
0.41
0.38
0.42
1.5
1.0
0.58
0.58
1.0
1.5
1.5
0.47
the average of duplicate
at about 200,000 Btu/hr;
half Method
5. 6Method
boiler fuel
6. Method
%
238
123
171
128
151
1€O
129
k
117
182
207
Particulates
5.0 (0.22)
7.8 (0.33)
6.8 (0.18)
2.8 (0.13)
4.8 (0.22)
5.8 (0.25)
44 (1.9)
20 (0.90)
26 (1.2)
34 (1.6)
4.0 (0.21)
Emission factor.
so,6
6.0"! (0.26)
11.
26 (1.2)
26 (1.2)
k
Condensable
organics
2.0 (0.087)
2.4 (0.10)
2.2 (0.089)
2.4 (0.11)
3.6 (0.16)
5.0 (0.22)
k
9.4 (0.42)
5.2 (0.25)
k
3.6 (0.19)
i
POM1
0.26 (0.011)
k
O.SB (0.023)
k
~k
"k
0.070 (0.0030)
k
~k
0.036 (0.0017)
_k
sampling runs.
feed rate
averaged 19.8
7. 9Drager tube. Back
Ib/hr when stoker was ON, furnace fuel feed rate averaged
half Method 5.
Modified Method 5 with XAO-2
resin trap.
15.5 Ib/hr
JData for ON segment of heating cycle only.
No data obtained due to program limitations.
-------
TABLE C-2. EMISSIONS DATA FOR BITUMINOUS COAL COMBUSTION3 (6)
o
to
Run
1
2
3
4
6
7
8
11
12
13
14
15
16
17
Coal
High volatile
bituminous
High volatile
bituminous
High volatile
bituminous
Western
Low volatile
Western
High volatile
Western
High volatile
bituminous
High volatile
bituminous
Western
Western
Western
High volatile
bituminous
Cycle
ON/OFF Time
min seqment
20/40 1*2
3*4
20/40 1 c 2
314
S0/I0d 1 S 2
3*4
20/40 112
3*4
20/40 1*2
3*4
20/40 1*2
3 C 4
20/40 1*2
3 c 4
20/40 1*2
3*4
20/40 1*2
3 S «
20/40 1*2
3*4
20/40 1 C 2
3 C 4
20/40 1*2
3*4
20/40 1*2
3*4
f
20/40 1*2
3*4
Firing
rate,c
0 Ib/hr
42
0
44
0
44
0
55
0
52
0
52
0
43
0
23
0
75
0
23
0
23
0
75
O
50
0
45
0
Note. — Blanks indicate data not available.
Data shown for runs 1 through 6 were combined
1 -
c
transient ON,
2 - steady-state
OB, 3 - tri
Air flow
Pria. Sec.
500
0
500
0
0
640
0
610
0
660
0
500
0
350
0
760
0
350
0
400
0
880
0
600
0
550
0
by MRC
insient
SO
0
50
0
50
0
60
0
60
0
53
0
50
0
0
0
75
0
40
0
40
0
85
O
60
100
60
100
•^2 »
percent
4.6 to 11.6
13.9 to 15.8
5.4 to 8.5
17.0 to 18.5
5.0 to 6.5
10.5 to 12.8
10.5 to 12.3
18.3 to 18.5
5.5 to 12.0
11.0 to 15.8
10.7 to 12.4
15 to 18
7 to 10
12 to 15
12.5 to 15.5
14.5 to 18.3
4 to 6
14 to 15
10 to 13
15 to 17
12 to 14
16 to U
5 to 7
14 to 18
9.5 to 12.8
15.5 to 18.2
9.5 to 11.0
15.0 to 17.5
to include transit
OFF,
C02,
percent
8.5 to 14.6
4.6 to 6.0
11.6 to 14.3
2.4 to 3.6
15.2 to 16.5
8.0 to 9.8
8.1 to 9.8
2.4 to 2.6
8.0 to 16.0
4.6 to 9.0
8.4 to 10.0
_ 1.8 to 2.2
9.4 to 11
4.1 to 6.7
2.0 to 7.0
1.9 to 3.0
13.0 to 13.8
4.2 to 5.6
6.5 to 7.9
3.5 to 4.5
6.3 to 9.0
2 to 4
13.4 to 14.8
2 to 5
7.1 to 10.2
1.9 to 5.2
7.6 to 9.6
2.6 to 3.8
S02.
600 to eoo
360 to 420
510 to 750
150 to 180
630 to 900
500 to 580
210 to 270
30 to 40
120 to 180
510 to 100
280 to 500
80 to 100
190 to 240
40 to 9O
:nt and steady-state CW tine
HO,
PP"°
160 to 20O
55 to 60
200 to 240
30 to 40
600 to 900
60 to 100
120 to 130
<40
120 to 170
30 to 50
80 to 100
10 to 30
200 to 250
40 to 70
120 to 170
40 to 70
100 to 130
40 to 60
150 to 190
25 to 50
100 to 140
40 to 90
220 to 280
50 to 80
segments.
Particulate
loading, POM loading, Particulate
mq/Nm3 ing/Urn3 emissions .
CO, ON OFF ON OFF g/lb
EEE cycle cycle cycle cycle coal feed
165 to >1,250 110 1,600 8.2 13 3.9
>1,250
60 to 100 190 1,400 8.81 21 41
>1,250
40 to 100 100 1,300 3.2 29 0 8*
>1,250
560 to 850 50 99 1.2 1.5 0.50
>1,2SO
<60 140 260 1.0 -12 14
>1,250
40 to 80 37 99 o 43
>1,250
40 to 160 110 590°
>1,250
150 to >1,250 45 61 0.53 0.22 1.0
>1,250
40 to 80 120 610 0.81 0.33 21
>1,250
>1,250 130 190 0.26 0.18 3 4
>1.250
100 to 140 50 94 0.44 0.17 0 77
>1,250
20 to 40 77 160 0.23 0.60 1 0
>1,250
50 to 150 37 87 0.98 0.58 0.60
>1,250
100 to 200 93 290 1.7 1.9 i 7
>1,250
- POM
emissions,
mg/lb
86
82
23
10.2
27
8.3
8.8
5.4
7 3
3.4
11.1
12.3
4 - steady-state OFF.
While OH.
Old not use data because of 50/10 cycle; use all data from 20/40 cycle.
Broken frit, run not used.
Modified cycle, run not used.
-------
TABLE C-3. POLYCYCLIC ORGANIC MATERIALS EMISSIONS DATA FOR
BITUMINOUS COAL COMBUSTION (38)
(micrograms per million Btu heat input)
Group 1
Group 2
Source Benz(a)-
number Firing Benzo(a)- Benzole)- Benzo(g,h,i)- Anthan- Anthra- Phenan- Fluoran- anthra-
in (38) method pyrene Pyrene pyrene Perylene perylene threne Cornene cene threne thene cene
7 Underfeed
stokers 3,800 7,700 5,400
8 Hand-stoked 400,000 600,000 100,000 60,000
580 1,200 29,000 47.000 560
300,000 90,000 30,000 400,000 1,000,000 1,000,000
Note.—Blanks indicate data not available.
O
U)
TABLE C-4.
POLYCYCLIC ORGANIC MATERIALS EMISSIONS DATA FOR BITUMINOUS COMBUSTION
(micrograms per million Btu heat input)
(39)
Sample
number
in (39)
34
36
59
60
57
58
-
Firing
method
Underfeed
stokers
Hand-stoked
Fuel
feed
rate.
Ib/hr
4.2
3.8
5.0
4.5
6.3
5.6
Gross
heat
input,
Btu/hr
58,000
56,000
70,000
63,000
89,000
80,000
Benzol a) -
pyrene
65,000
81,000
67,000
8,600
1,700,000
3,300,000
Pyrene
300,000
190,000
160,000
45,000 -
2,700,000
9,100,000
Benzole) -
pyrene
39,000
59.000
55,000
7,700
870,000
1,500,000
Group 1
Perylene
7,900
4,800
5,500
430
220,000
350,000
Benzo(g,g,i)-
perylene
61,000
58,000
59,000
6,300
1,400,000
2,200,000
Anthan-
threne
6,100
3,000
1.300
270,000
490,000
Cornene
4,100
3,400
49,000
97,000
Anthra-
cene
70,000
48,000
14,000
1,300
1,100,000
2,900,000
Group 2
Phenan-
threne
610,000
350,000
170,000
51 , 000
2.300,000
7,500,000
Fluoran-
threne
330,000
150,000
320,000
76,000
4,300,000
11,000,000
Mote.—Blanks indicate data not available.
-------
TABLE C-5.
EMISSION DATA FOR BITUMINOUS
COAL COMBUSTION (38)
Source
number
in (38)
7
8
Firing
method
Underfeed
stoker
Hand-stoked
Fuel
feed
rate.
lb/hr
4.3
8
Gross
Total
heat particulates , CO,
input ,
Btu/hr
66,000
115,000
Ib/ton
of fuel
12
37
Ib/ton
of fuel
1.1
3.5
Hydrocarbons
NOC
(as methane) , (as NO2) ,
Ib/ton
of fuel
3.3
21
Ib/ton
of fuel
9.8
3.2
SOX
(as S02) ,
Ib/ton
of fuel
32
- 15
Formaldehyde ,
Ib/ton
of fuel
24 x 10-"
Note.—Blanks indicate data not available.
TABLE C-6,
EMISSIONS DATA FOR BITUMINOUS COAL COMBUSTION
IN A RESIDENTIAL FIREPLACE FROM RUN NO. 13,
STABLE CONDITIONS (30)
2.7
Stack Particulate Nonmethane
Burning gas flow emission volatile
va^u' rf^e' factor, POM, CO, hydrocarbons,
kg/hr NmVmin g/kg ng/Nm3 ppm ppm
11,597
14.4
Note.—Blanks indicate data not available.
-------
TABLE C-7. EMISSIONS DATA FOR ANTHRACITE COAL COMBUSTION (6)
Run
from (6)
9
10
Cycle,
ON/OFF
mm
20/40
SO/10
Time .
segment
1 & 2
3 & 4
1 & 2
3
Firing
rate,c
Ib/hr
67
0
67
0
Air flow
rate.
Prim.
fan
0
fan
0
Ib/hr
Sec.
0
0
0
0
02,
percent
10.0 to 12.6
16 to 17
7 to 10
13 to 15
C02,
percent
8.4 to 10.0
3.3 to 3.7
9.6 to 12.5
6 to 8
S02,
ppm
200 to
60 to
240 to
130 to
240
100
280
150
NO,
ppm
30 to 40
10 to 15
60 to 90
30 to 40
CO,
ppm
150 to >80
>1,250 to >1,250
50 to 640
>1,250
Particulate
loading, POM loading, Particulate POM
Cycle, mg/Nm^ mg/Nm^ emissions, emissions,
Run ' ON/OFF ON OFF ON OFF g/lb mg/lb
from (6) min cycle cycle cycle cycle coal fed coal fed
9
10
20/40
50/10
73
160
11
54
0.12
0.21
0.15
0.11
0.33
0.70
0.86
0.12 ,
Data shown for runs 9 and 10 were combined by MRC to include transient ON and steady-state ON time segments.
1 - transient ON; 2 - steady-state ON; 3 - transient OFF- 4 - steady-state OFF.
CWhile ON.
-------
On run 1 (6) , for example, the air feed rate during the ON seg-
ment is 550 Ib/hr, the particulate emission factor is 3.9 g/lb
over the whole cycle, the particulate loading is 110 mg/Nm* dur
ing the ON segment and 1,600 mg/Nm3 during the OFF segment, and
the cycle is 20 minutes ON and 40 minutes OFF.
Calculation of the volume of stack gas during each segment is
shown below:
For the ON segment:
_ = 3/
hr x lb x 1.293 g x 1,000 £, iyj m /n
550 lb 454 g I _ m3
b x 1.293 g x 1,000
193 m3 x -- = 207 Nm3/hr
--
For the OFF segment, it is first necessary to determine the
amount of particulates emitted during each time segment.
For the ON segment:
207 Nm3 110 mg q - 22 B a/hr
— fir - x Nm3* x 1,000 mg ~ 22'8 g/hr
or:
22.8 g hr 20 min _ , . „.
— -^ x - x - = 7'6 9/cycle
60-iiK
Since the overall emission factor is 3.9 g/lb, then:
3.9 g 42 lb coal 20 min = 4 a/cvcle
lb x hr x 60 min 54t6 9'cvcle
For the OFF segment, the particulates emitted are:
54.6 g/cycle - 7.6 g/cycle =47.0 g/cycle
or:
47.0 g cycle 60 min = 70 5 a/hr
cycle x 40 min x hr /0':> g/nr
With this, the volume of flue gas emitted during the OFF segment
can be calculated using the corresponding particulate loading:
70.5 g Nm3 1,000 mg ..
-hF^ X 1,600 mg X - g - ^ = 44
106
-------
Using these calculated flue gas rates, the emission factors for
pollutant gases can be determined, as in the following example
for S02. Approximately 700 ppm S02 in the flue gas during the
ON segment and about 390 ppm during the OFF segment were
reported (6):
0.0007 x 20Z Nm = 0.145 Nm3/hr of S02
hr
and
0.00039 x 44h^in = 0.017 Nm3/hr of S02
This must be converted to the volume at 0°C to determine the
weight of the gas.
m3/hr @ 0°C
no. t. y j t\
and
x
= 0.016 m3/hr. @ 0°C
Using the fact that one gram-mole of gas at 0°C occupies 22.4 £
of volume, the amount of each gas can be determined as below
for S02.
For the ON segment:
0.135 m3 1,000 & g-mole hr 20 min
hr iPx 22.4 A x 60 min cycle
= 2.01 g-mole/cycle of SO2
For the OFF segment:
0.017 m3 1,000 I g-mole hr 40 min
hr x m3 x 22.4 Jl 60 min cycle
= 0.51 g-mole/cycle of S02
Combining for the total cycle, the emission factor can be calcu-
lated as follows:
g-mole 0.51 g-mole\ 64 g S02 cycle
.*-. i**. -,_„_ i _ / 2C _ _ 1 ^ ^1^11—-.-
lb
cycle cycle / g-mole 14 lb coal 0.454 kg
= 25.4 g S02/kg coal
107
-------
Runs 11 and 13 of the study(6) were not used because the calcu-
lated flue gas volumes during the ON and OFF phases were nearly
identical, and this would not occur under normal operation.
ANTHRACITE COAL COMBUSTION
Emission factors for residential combustion of anthracite coal
were obtained from the study(6) discussed under bituminous coal
combustion. Like the bituminous runs, the anthracite particulate
and POM emission factors were provided in g/lb and mg/lb respec-
tively, while CO, SO2, and NO were given as concentrations in the
flue gas and were listed separately for the ON and OFF segments
of the furnace cycle. However, for anthracite test runs, the
combustion air flow rate was not measured. Therefore, to obtain
the stack gas volume, material balances were made. The carbon
balance below is an example.
Assuming that C02 and CO concentrations in the air feed are zero,
Carbon in coal = carbon in flue gas as C0£ and CO
The analysis (6) of the test coal showed 79.4% carbon; for test
run 9, the following calculation was performed:
i x ii 1.98 kg \ / 12 1.25 kg)]
.i x 44 x —^ -j+ ^u.uuui x 28 x ST-'y]
For the ON segment (C02 - 10%, CO * 100 ppm),
Coal! x 0.794 = V
or
Vi = 14.7 Coali (C-l)
where Vi = stack gas volume during ON segment, m3/hr
Coali = coal burned during ON segment, kg/hr
For the OFF segment, (C02 - 3.3%, CO = 1,300 ppm),
Vi = 42.9 Coal2 (C-2)
where V2 = stack gas volume during OFF segment, m3/hr
Coal2 = coal burned during OFF segment, kg/hr
The anthracite feed rate on run 9 was 67 Ib/hr or 30.4 kg/hr, and
the furnace cycle was 20 min ON/40 min OFF; therefore,
„ 20 . 40 30.4 kg 20
x + Coal2 x —S x
108
-------
or
Coali + 2 Coal2 = 30.4 (C-3)
To solve these equations, the ratio of Vi to V2 is assumed to be
about 4, based on the ratios for bituminous coal. Substituting
this into Equation C-l gives
4 V2 = 14.7
Substituting for coali , Equation C-3 gives
4 V2 = 14.7 (30.4 - 2 Coal2)
or
Coal2 = 15.2 - 0.136 V2 (C-4)
Substituting this into Equation C-2 gives
V2 = 42.9 (15.2 - 0.136 V2 )
_ 95.5 m3
2 hr
v, = 4 x ^JJF^
Vi = 382 m3/hr
With values for Vi and V2, the procedure for determining emission
factors is the same as that used with bituminous coal data (6).
The emission factor for hydrocarbons was taken from AP-42 (40).
LIGNITE-FIRED COMBUSTION
No reliable emission data were found on residential combustion of
lignite coal; therefore the engineering estimates provided in
AP-42 (40) were used for emission factors.
109
-------
APPENDIX D
POM EMISSION FACTORS FOR VARIOUS FOSSIL-FUELED
BOILERS AND FURNACES
Because POM emissions may pose a serious health threat to the
general public, the level of POM emissions from residential coal
combustion was put into perspective with other fossil-fueled com-
bution sources of a similar nature. To compare POM emission
factors as grams per kilogram of fuel presented a problem when
comparing coal-, oil-, and gas-fired combustion processes because
the common unit of comparison was based on the heating value of
the fuel, or mass emissions of POM per unit of available heat
(pg/J)a. Data for comparison were obtained from Reference 2
except for residential coal combustion, which data came from this
report. Data were converted into the common units of pg/J.
Table 14 in this report presented a POM emission factor of
0.058 g/kg for residential bituminous coal combustion while
Table 9 presented an average heating value for bituminous coal
of 30 MJ/kg. Therefore:
0.05 g/kg 10^ pg/g _
30 MJ/kg X 106 J/MJ ~ 1'933 pg/J
Reference 2 presented a POM emission factor of 885 yg/106 Btu for
coal-fired utility boilers. Therefore:
=0.839 pg/J
POM emission data for residential gas and oil combustion, com-
mercial/institutional coal combustion, and industrial coal
combustion were also presented in Reference 2 but in a somewhat
different form. Total annual emissions of POM's in tons per
year and total fuel usage in 1012 Btu per year were given. This
information was converted into emission factors as follows:
ton POM yr 2,000 lb 454 x IP"12 pg Btu _ /T
yr x 1012 Btu x ton x lb x 1,055 J ~ Pg/J
The results of these computations are presented in Section 4 of
this report.
a
picogram per joule; 1 gram = 1 x 1012 picograms.
110
-------
APPENDIX E
DERIVATION OF SOURCE SEVERITY AND AFFECTED
POPULATION EQUATIONS
SUMMARY OF SEVERITY EQUATIONS
The severity (S) of pollutants may be calculated using the mass
emission rate, Q, the height of the emissions, H, and the ambient
air quality standard or the threshold limit value, TLV (54).
The equations summarized in Talbe E-l are developed in detail in
this appendix.
TABLE E-l. POLLUTANT SEVERITY EQUATIONS
FOR ELEVATED POINT SOURCES
Pollutants
Particulate
S0x
N°x
Hydrocarbon
CO
Severity equation
s .2|jfl
Bm*&
S = 315 Q
s = 162 Q
r . 0.78 Q
H2
Other s = 5>5 Q .
& TLV • H2
DERIVATION OF Xmax FOR USE WITH U.S. AVERAGE CONDITIONS
The most widely accepted formula for predicting downwind ground
level concentrations from a point source is (52)
X =
Ill
-------
where x = downwind ground level concentration at reference
coordinate x and y with emission height of H, g/m3
Q = mass emission rate, g/s
OTT = 3.14
y = standard deviation of horizontal dispersion, m
z = standard deviation of vertical dispersion, m
u = wind speed, m/s
y = horizontal distance from centerline of dispersion, m
H = height of emission release, m
x = downwind dispersion distance from source of emission
release, m
It is assumed that Xmax occurs when x is much greater than 0 and
y equals 0. For a given stability class, standard deviation of
horizontal and vertical dispersion have often been expressed as a
function of downwind distance by power law relationships as fol-
lows (80) :
a = axb (E-2)
a = cxd + f (E-3)
Z
Values for a, b, c, d, and f are given in Tables E-2 and E-3.
Substituting these general equations into Equation E-l yields
X = xZ^ K expl ^ 1 (E_4)
acirux + airufx 2 (ex
"I
+ f)*]
Assuming that Xmax occurs at x less than 100 m or the stability
class is C, then f equals 0 and Equation E-4 becomes
x = —expl—^1 (E-5)
aCTTUX
For convenience, let
and B =
2c2
so that Equation E-5 reduces to
(80) Martin, D. 0., and J. A. Tikvart. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. Presented at the 61st Annual
Meeting of the Air Pollution Control Association, St. Paul,
Minnesota, June 23-27, 1968. 18 pp.
112
-------
TABLE E-2.
VALUES OF a FOR THE
COMPUTATION OF a a (81)
Stability class
A
B
C
D
E
F
a
0.3658
0.2751
0.2089
0.1471
0.1046
0.0722
TABLE E-3.
For the equation
oy = axb
where x = .downwind distance
b = 0.9031 (from
Reference 82)
VALUES OF THE CONSTANTS USED TO
ESTIMATE VERTICAL DISPERSION3 (81)
Usable range, Stability
m class Coefficient
>1,000 A
B
C
D
E
F
100 to 1,000 A
B
C
D
E
F
<100 A
B
C
D
E
F
BFor the equation
0.
c,
0.00024
0.055
0.113
1.26
6.73
18.05
C2
0.0015
0.028
0.113
0.222
0.211
0.086
= 3
0.192
0.156
0.116
0.079
0.063
0.053
- cxd + f
dj
2.094
1.098
0.911
0.516
0.305
0.18
d2
1.941
1.149
0.911
0.725
0.678
0.74
d3
0.936
0.922
0.905
0.881
0.871
0.814
f,
-9.6
2.0
0.0
-13
-34
-48.6
*2
9.27
3.3
0.0
-1.7
-1.3
-0.35
13
0
0
0
0
0
0
(81) Eimutis, E. C., and M. G. Konicek. Derivations of Continu-
ous Functions for the Lateral and Vertical Atmospheric Dis-
perios Coefficients. Atmospheric Environment, 6(11):859-
863, 1972.
(82) Tadmor, J., and Y. Gur. Analytical Expressions for the
Vertical and Lateral Dispersion Coefficients in Atmospheric
Diffusion. Atmospheric Environment, 3(6):688-689, 1969.
113
-------
-&]
(E-6)
Taking the first derivative of Equation E-6
-b-d lx
-b-d-1
(E-7)
and setting this equal to zero (to determine the roots which
give the minimum and maximum conditions of x with respect to x)
yields
o .
exp
y-1)
-2dBDx~2d-b-d
K
(E-8)
Because it is known that x ± 0 or « at xmax' the following expres-
sion must be equal to 0.
-2dBRx~2d-d-b = 0
(E-9)
or
(b+d)x2d = -2dBT
(E-10)
or
2d _ "2dBR
b+d 2c2{b+d)
(E-ll)
or
2d
c2 (b+d)
(E-12)
or
x -I dH2 \ 2d at
X
(E-13)
Thus Equations E-2 and E-3 become
a .
y
c2(d+b)
(E-14)
114
-------
°z = c[— ) =[ 1 (E-15)
The maximum will be determined for U.S. average conditions of
stability. According to Gifford (83), this is when o equals oz-
Since b equals 0.9031, and upon inspection of Table E-2 under
U.S. average conditions, Oy equals oz, it can be seen that
0.881 is less than or equal to d which is less than or equal to
0.905 (class C stability3). Thus, it can be assumed that b is
nearly equal to d or
0 = _J1 (E-16)
2 /~-
0 = £L JL (E-17)
and
f'y c /i
Under U.S. average conditions, oy equals oz and a approximates c
if b approximates d and f equals 0 (between class C and D, but
closer to belonging in class C) .
Then
o = — (E-18)
Substituting for o and o into Equation E-l and letting
y equal 0 ^
[/ \21
\ / J
or
1 r\
(E-20)
aThe values given in Table E-3 are mean values for stability
class. Class c stability describes these coefficients and
exponents, only within about a factor of two (52).
(83) Gifford, F. A., Jr. An Outline of Theories of Diffusion in
the Lower Layers of the Atmosphere. In: Meteorology and
Atomic Energy 1968, Chapter 3, D. A. Slade, ed. Publication
No. TID-24190, U.S. Atomic Energy Commission Technical
Information Center, Oak Ridge, Tennessee, July 1968.
p. 113.
115
-------
For U.S. average conditions, u equals 4.47 m/s so that
Equation E-20 reduces to
0.0524 Q
*max -- ~2 - (E-2D
DEVELOPMENT OF SOURCE SEVERITY EQUATIONS
The general source severity, S, relationship has been defined as
follows:
S = BM (E-22)
where Xmax = time-averaged maximum ground level concentration
F = hazard factor
Noncriteria Emissions
The value of Xmax mav ^e derived from Xmax' an undefined "short-
term" concentration. An approximation for longer term concen-
tration may be made as follows (52) :
For a 24-hr time period,
o.i?
*max= ^ 2
-------
105
TLV^ 5 Q (E-36)
TLV • H2
Criteria Emissions
For the criteria pollutants, established standards may be used
as F values in Equation E-22. These are given in Table E-4 (53) .
117
-------
However, Equation K-23 must be used to give the appropriate
averaging period. These equations are developed for elevated
sources using Equation E-21.
TABLE E-4.
SUMMARY OF NATIONAL AMBIENT AIR
QUALITY STANDARDS (53)
Pollutant
Particulate matter
sov
X
CO
Nitrogen dioxide
Photochemical oxidants
Hydrocarbons (nonme thane)
Averaging time
Annual (geometric mean)
24-hrb
Annual (arithmetic mean)
24-hr6
3-hrb
8-hrg
l-hr°
Annual (arithmetic mean)
l-hrb
3-hr (6 a.m. to 9 a.m.)
Primary
standards,
ug/m3
75
260
60
365,
_0
10,000
40,000
100
160
160*
Secondary
standards,
pg/m3
60*
160
60,
260°
1,300
10,000
40,000
100
160
160
The secondary annual standard (60 pg/m3) is a guide for assessing implementa-
tion plans to achieve the 24-hr secondary standard.
bNot to be exceeded more than once per year.
CNo standard exists.
The secondary annual standard (260 ug/m3) is a guide for assessing implementa-
tion plans to achieve the annual standard.
'There is no primary ambient air quality standard for hydrocarbons. The value
of 160 ug/m3 used for hydrocarbons in this report is an EPA-recommended guide-
line for meeting the primary ambient air quality standard for oxidants.
Carbon Monoxide Severity—
The primary standard for CO is reported for a 1-hr averaging
time. Therefore
t = 60 min
t = 3 min
o
0.17
vmax
max
(E-37)
= 2 Q /_3\0>17
TreuH2 \60/
B _ 2 Q _
(3.14) (2.72) (4.5)H2
0.052 Q
0.6
H2
0.6
(3.12 x 10"2)Q
"-max
(E-38)
(E-39)
(E-40)
(E-50)
118
-------
Severity, S = -^- (E-42)
Setting F equal to the primary standard for CO; i.e., 0.04 g/m3 ,
yields
0.12 x 10^)Q (£_43)
F 0.04 H2
or
*co • ^
Hydrocarbon Severity —
The primary standard for hydrocarbon is reported for a 3-hr
averaging time.
t = 180 min
t = 3 min
xmax = *max
3 \°-17
TQQ)
-------
/ 3 \
xmax = xmaxU,440/
3 \ ° • 1
• 1 7
_ (0.05) (0.052)0 ,_
(E
H2
0.0182 Q
*max = - ~2 - (B-53)
For participates, F = 2.6 x 10~** g/m3, and
Xmax = 0.0182 Q (E-54)
F (2.6 x lQ-
Sp = (E-55)
P H2
S0y Severity —
The primary standard for SO is reported for a 24-hr averaging
time.
- = 0.0182 Q
xmax H2 (E-56)
The primary standard is 3.65 x 10~k g/m3. Therefore,
S- = - 0-0182 Q - (E_5?)
F (3.65 x IQ-
or
S_0 = 50-Q (E-58)
S°x H2
N0y Severity —
Since NOX has a primary standard with a 1-yr averaging time, the
Xmax correction equation cannot be used. As an alternative, the
following equation is used:
(E-59)
A difficulty arises, however, because a distance x, from emission
point to receptor, is included; hence, the following rationale is
used:
120
-------
x -
mSX 7T8UH2
is valid for neutral conditions or when oz equals o . This
maximum occurs when
H-
and since, under these conditions,
oz = axb
then the distance, x , where the maximum concentration occurs is
max
xmax
For class C conditions,
a = 0.113
b = 0.911
Simplifying Equation E-59,
". • °'113 "max0'"1
and
u = 4.5 m/s
Letting x = xmax *n Equation E-59,
X = i_S expl- x- l~\ I (E-60)
*max i.9ii **! 2 lo I I V* ou;
max
where
H \i .096
xmax
... _ 7 c Hi. 098 (E-62)
xmax ~ '*3 "
and
4 Q 4Q
rm = n R Hi.096vi.9li (B-63)
xmax (7'5 H }
121
-------
Therefore,
n not; n f 1 / H\2T
(E-64)
As noted above,
oz = 0.113 x°-911 (E-65)
ci = 0.113(7.5 H1-1)0-911 (E-66)
Z
or
Therefore,
o = 0.71 H (E-67)
Z
- = 0^081_Q f 1 /_H_V (E-68)
*max H2.i |^ 2 y0.71 H/ J
= °-°85 Q (0.371) (E-69)
H2.1
v = 3'15 * 10"2 Q (E-70)
H2.1
Since the NO standard is 1.0 x 10~u g/m3, the N0x severity
eauation is
equation is
s = (3.15 x 10"2)Q
i x 10"* H2-1
'NO
(E-71)
q _ 315 Q . -.
&Mr> ~ ! (&-/t)
N°X H2- 1
AFFECTED POPULATION CALCULATION
Another form of the plume dispersion equation is needed to
calculate the affected population since the population is assumed
to be distributed uniformly around the source. If the wind direc-
tions are taken to 16 points and it is assumed that the wind
directions within each sector are distributed randomly over a period
of a month or a season, it can be assumed that the effluent is
uniformly distributed in the horizontal within the sector. The
appropriate equation for average concentration (x) is then:
122
-------
r. i /H_VI
I 2U)J
To find the distances at which x/F = 0.1, roots are determined for
the following equation:
0 =
2.03 Q
Fa ux
(E-74)
keeping in mind that:
= a x + c
where a, b, and c are functions of atmospheric stability and are
assumed to be for stability Class C.
Since equation E-74 is a transcendental equation, the roots are
found by an iterative technique using the computer.
For a specified emission from a typical source, x/F as a function
of distance might look as follows:
A "• *
F
J
/
/
xl
'^
\.
The affected population is then in the area
A = Tr(Xa - Xi
(E-75)
If the affected population density is D then the total affected
population, P, is P'
P = DA (persons)
(E-76)
123
-------
APPENDIX F
TOTAL COAL-FIRED RESIDENTIAL COMBUSTION EMISSIONS
Total criteria emissions from coal-fired residential combustion
equipment were compared on state and national bases to emissions
from all stationary sources. State emissions were calculated by
multiplying the emission factors presented in Section 4 by the
estimated fuel usage in each state for each source. In the case
of bituminous coal state emissions were determined by weighting
an emission factor to represent the distribution of automatic
and hand-fed heating equipment. Table B-2 in Appendix B shows
that 60% of residential heating takes place in furnaces and
boilers that are assumed to be automatic devices. The emission
factor for hand-fed units was determined from Table 16 in
Section 4. Table F-l shows the emission factors for automatic
and hand-fed equipment and the average emission factor weighted
by percent automatic and hand-fed equipment.
TABLE F-l.
WEIGHTED AVERAGE EMISSION FACTORS FOR
CRITERIA POLLUTANTS FROM BITUMINOUS
COAL-FIRED RESIDENTIAL COMBUSTION UNITS
(g/kg)
Emission
species
Particulate
SOX
NOX
Hydrocarbon
CO
Automatic
equipment
(60%)
5.1
15. OS
3.9
1.8
13.0
Hand- fed
equipment
(40%)
13
16. OS
1.6
5
50.0
Weighted
average
8.3
15. 5S
3.0
3.1
28.0
State emissions of SOX from residential bituminous coal combus-
tion were determined by using the average sulfur content of the
coal most likely to be used by the residential sector in each
state. Coal origin and sulfur content are presented by state in
Table F-2. Tables F-3, F-4f and F-5 give the criteria emissions
and emission ratios by state and on a national level for each
source. Total state emissions were taken from the NEDS inventory
(84) which is shown in Table F-6.
124
-------
TABLE F-2.
ORIGIN OF RESIDENTIAL BITUMINOUS
COAL AND SULFUR CONTENT3
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Mexico
New York
North Carolina
Ohio
Oklahoma
Oregon
Pennsylvania
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Washington
West Virginia
Wisconsin
Wyoming
a : •
Region of
coal origin
(20, 26)
GP
AL
RM
IP
RM
RM
A
GP
A
PC
RM
IP
IP
IP
IP
A
GP
A
A
IP
GP
IP
NGP
IP
RM
RM
A
A
A
IP
PC
A
A
NGP
A
IP
RM
A
PC
A
A
RM
Average sulfur
content (20) , %
1.9
0.2
0.6
3.9
0.6
0.6
2.3
1.9
2.3
0.4
0.6
3.9
3.9
3.9
3.9
2.3
1.9
2.3
2.3
3.9
1.9
3.9
1.2
3.9
0.6
0.6
.2.3
2.3
2.3
3.9
0.4
2.3
2.3
1.2
2.3
3.9
0. 6
2.3
0.4
2.3
2. 3
0.6
Abbreviations used: A - Appalachain Region; AL -
Alaska; GP - Gulf Province; IP - Interior Province;
NGP - Northern Great Plains Province/ PC - Pacific
Coast Province; RM - Rocky Mountain Province.
125
-------
TABLE F-3.
STATE-BY-STATE LISTING OF RESIDENTIAL
BITUMINOUS COAL-FIRED EMISSIONS
to
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Zowa
Kansas
Kentucky
Louisiana
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Mexico
New York
North Carolina
Ohio
Oklahoma
Oregon
Pennsylvania
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Total
Fuel
usage,
metric
tons/yr
61,264
6,222
363
4,461
1,667
21,782
16,221
176
8,118
15
23,125
216,670
28,547
10,322
869
242,317
66
4,278
22,448
26,050
5,453
7,021
8,785
1,897
1,112
1,207
1,663
69,434
60,185
758
2,772
216,528
25,932
4,405
220,007
365
29,427
166,946
10,945
185,318
21,332
7,683
1,744,156
Metric tons
Partic-
ulates
507
51
3.0
37
14
180
134
1.6
67
0.1
191
1,792
235
86
8.0
2,003
0.5
35
186
215
46
59
73
16
9.5
9.5
14
574
498
6.4
22
1,790
215
37
1,819
3.2
243
1,380
91
1,533
176
64
14,425
S0x
1,806
19
3.4
270
16
203
579
5.2
290
0.1
215
13,114
1,728
625
52
8,649
1.9
152
801
1,577
161
425
164
114
11
12
59
2,478
2,149
46
17
7,729
925
82
7,853
22
274
5,960
68
6,615
761
72
66,104
N0x
183
18
1.1
13
5.0
65
48
0.5
24
0.04
69
647
85
31
2.6
724
0.2
12
67
78
17
21
27
5.6
3.3
3.6
5.0
208
180
2.2
8.3
647
77
13
657
1.1
88
499
32
554
64
23
5,210
Hydro-
carbons
189
19
1.1
13
5.1
67
50
0.6
25
0.05
71
668
88
32
2.7
747
0.2
13
70
81
17
21
27
5.8
3.4
3.7
5.1
214
186
2.4
8.7
667
80
13
678
1.1
91
514
34
571
66
24
5,376
CO
1,686
172
10
123
45
599
447
4.9
224
0.5
637
5,967
786
284
24
6,673
1.8
118
619
718
151
193
241
52
31
34
45
1,912
1,657
21
76
5,963
714
122
6,059
10
810
4,598
301
5,103
588
212
58,032
Percent of total state emissions
Partic-
ulates
0.04
0.3
<0.01
0.03
<0.01
0.1
0.6
<0.01
0.02
<0.01
0.3
0.2
0.03
0.03
<0.01
0.3
<0.01
0.03
0.03
0.08
0.03
0.03
0.03
0.02
0.01
<0.01
<0.01
0.1
O.O3
<0.01
O.O1
0.1
0.1
0.6
0.4
<0.01
0.3
0.3
0.06
0.7
0.5
0.08
O.OB
S°x
0.2
0.3
<0.01
0.7
<0.01
0.4
1.0
<0.01
0.06
<0.01
0.4
0.7
0.09
0.2
0.06
0.7
<0, 01
0.02
0.06
0.4
0.3
0.04
0.02
0.2
<0.01
<0.01
0.02
0.5
0.07
0.04
O.05
0.3
0.4
0.5
0.7
<0.01
0.18
1.4
0.03
1.0
0.1
0.1
0.2
NO
X
0.05
0.06
<0.01
<0.01
<0.01
0.04
0.08
<0.01
<0.01
<0.01
0:2
O.07
-------
TABLE F-4. STATE-BY-STATE LISTING OF RESIDENTIAL ANTHRACITE-FIRED EMISSIONS
to
State
Connecticut
Delaware
Fuel
usage,
metric Partic-
tons/yr ulates
5,644 6
3,690 4
District of Columbia 2,195 2
Illinois
Indiana
Maine
Maryland
Massachusetts
Michigan
New Hampshire
New Jersey
New York
Ohio
Pennsylvania
Rhode Island
Vermont
Total
4,462 5
6,972 8
1,783 2
48,285 53
14,693 16
7,701 8
942 1
63,140 69
132,246 145 1
6,517 7
552,942 608 4
932 1
2,057 2
854,201 937 6
Metric tons
SO NO
X X
45 5
30 3
17 2
36 4
57 6
14 1
391 44
119 14
62 7
7 1
511 57
,072 119
53 6
,478 498
7 1
17 2
,916 769
TABLE F-5. LIGNITE-FIRED
Emission
species
Particulates
SOX
NOX
Hydrocarbons
CO
Metric
tons
244
423
56
9
19
Hydro-
carbons CO
7 47
5 32
3 18
6 37
9 58
2 15
63 401
19 122
10 64
1 8
82 525
172 1,098
8 54
719 4,593
1 8
3 17
1,110 7,089
EMISSIONS
Percent of
total state
emissions
0.3
0.5
<0.1
<0.1
<0.1
Percent of total state emissions
Partic- SQ NQ Hydro-
ulates x x carbons CO
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 0.1 <0.1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0,1 <0.1 <0^1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 0.1 <0.1 <0.1 <0.1
<0.1 0.3 <0.1 <0.1 <0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 0.1 <0.1 <0.1 0.1
<0.1 <0.1 <0.1 <0.1 <0.1
<0.1 0.1 <0.1 <0.1 <0.1
Percent of U.S. Emissions
<0.01 0.02 <0.01 <0.01 0.01
a
IN NORTH DAKOTA
Percent
of U.S.
emissions
<0.01
<0.01
<0.01
<0.01
<0.01
Based on fuel usage of 18,784 metric tons/yr.
-------
TABLE F-6.
NEDS EMISSION SUMMARY BY,STATE (84)
(metric tons)
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Dist. Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Particulates
1,178,643
13,913
72,685
137,817
1,006,452
201,166
40,074
36,808
19,451
226,460
404,574
61,621
55,49.9
1,143,027
748,405
216,493
348,351
546,214
380,551
49,155
494,921
96,160
705,921
266,230
168,355
202,435
272,688
95,338
94,040
14,920
151,768
102,785
160,044
481,017
78,978
1,766,056
93,595
169,449
1,810,598
13,073
198,767
52,336
409,704
549,399
71,692
14,587
477,494
161,934
213,715
411,558
75,427
S°x
882,731
5,874
1,679,768
39,923
393,326
49,188
168,068
209,310
60,630
897,381
472,418
45,981
54,387
2,043,020
2,050,541
283,416
86,974
1,202,827
166,664
144,887
420,037
636,466
1,466,935
391,633
50,591
1,152,373
871,235
58,014
304,8.51
86,596
463,736
444,310
345,979
473,020
78,537
2,980,333
130,705
36,776
2,929,137
65,761
247,833
17,354
1,179,982
753,098
152,526
17,751
447,394
272,991
678,348
712,393
69,394
"°x
397,068
32,757
123,871
168,989
1,663,139
147,496
155,832
58,407
46,824
644,794
369,817
44,221
48,552
974,372
1,371,233
242,524
233,987
419,142
442,817
76,741
265,204
334,379
2,222,438
311,834
172,519
448,300
148,405
101,948
88,933
67,309
489,216
199,181
572,451
412,599
85,708
1,101,470
222,687
135,748
3,017,345
46,921
521,544
49,490
426,454
1,303,801
' 80,998
24,286
329,308
187,923
229,598
408,525
72,572
Hydrocarbons
643,410
28,389
189,981
195,538
2,160,710
193,456
219,661
63,886
41,789
619,872
458,010
89,530
84,230
1,825,913
600,477
316,617
309,633
326,265
1,919,662
122,918
295,867
440,481
717,891
410,674
195,950
413,130
271,824
127,821
53,673
88,469
819,482
152,057
1,262,206
447,238
70,289
1,153,493
341,358
234,669
891,763
65,833
907,833
90,478
362,928
2,218,891
98,282
41,980
369,416
344,643
116,155
523,930
55,319
CO
1,885,657
167,357
815,454
843,204
8,237,667
875,781
897,580
204,227
190,834
2,695,817
2,036,010
275,566
343,720
6,412,718
2,933,780
1,440,621
1,002,375
1,189,932
5,633,827
376,196
1,261,804
1,682,218
3,243,526
1,760,749
829,094
1,854,901
611,061
569,522
215,751
256,380
2,877,319
504,249
4,881,922
1,734,398
318,679
5,205,719
1,456,627
929,247
3,729,830
283,650
4,222,168
387,356
1,469,253
6,897,748
402,527
150,510
1,548,031
1,659,117
494,214
1,582,869
303,297
ADJUSTMENTS TO GRAND TOTAI.
The United States summary does not include certain1 "source categories. The following
additions should be considered part of the United States grand total for a more
accurate picture of nationwide emissions.
New York
pt. sources 311,000 993,000 382,000 127,000 44,000
Forest wild fires 375,000 0 88,000 529,000 3,089,000
Agricultural burning 272,000 15,000 29,000 272,000 1,451,000
Structural fires 52,000 0 6,000 61,000 200,000
Coal refuse piles 100,000 128,000 31,000 62,000 308,000
Total 1,110,000 1,076,000 536,000- 1,051,000 5,086,000
U.S. subtotal
(above) 16,762,000 28,873,000 21,722,000 23,994,000 91,782,000
U.S. grand totalj17,872,000 29,949,000 22,258,000 25,045,000 96,868,000
(84) 1972 National Emissions Report; National Emissions Data
System (NEDS) of the Aerometric and Emissions Reporting
System (AEROS). EPA-450/2-74-012, U.S. Environmental Pro-
tection Agency, Research Triangle Park, North Carolina,
June 1974. 422 pp.
128
-------
GLOSSARY
affected population: Number of persons around a representative
source who are exposed to a source severity greater than 0.1
or 1.0 as specified.
anthracite: Dense hard coal with a very high percentage of fixed
carbon, usually about 90%. Most anthracite is mined in
Pennsylvania.
barometric damper: Balanced butterfly gate located outside the
flue gas flow on an exhaust stack in a tee fitting. It is
used to control draft.
bituminous: Coal covering a wide range of properties, but in
general with a fixed carbon content under 80% and volatile
matter over 20%.
boiler: Closed vessel in which fuel is burned to generate
steam or heat water.
blow holes: Holes formed in a caked fuel bed from the force of
mechanically delivered combustion air.
caking coals: Coals that fuse and lose their shape during com-
bustion. The degree of caking is measured by the free
swelling index.
clinker: Fused mass of the residue (ash) from coal combustion.
criteria emissions: Those for which air quality standards have
been established.
cycle: Pattern of operation of automatic heating equipment
characterized by four segments; initial ON, steady-state
ON, initial OFF, and steady-state OFF.
damper: Valve or place used to regulate the flow of air to a
combustion process.
degree day: Unit representing a one degree Fahrenheit departure
below 65°F in the mean outdoor temperature for one day.
129
-------
draft: Gas flow resulting from the pressure difference between
the combustion unit and the atmosphere, which moves the pro-
ducts of combustion from the combustion unit to the atmo-
sphere. 1) Natural: the negative pressure created by the
difference in density between the hot flue gases and the
atmosphere. 2) Induced: the negative pressure created by
the action of a fan, blower, or ejector which is located
between the combustion unit and the stack. 3) Forced: the
positive pressure created by the action of a fan or blower,
which supplies the primary or secondary air.
emission factor: Quantify of emissions per quantity of mass
burned.
free swelling index: Measure of the caking properties of coal
determined by the volume change in coal during its plastic
stage.
flue: Enclosed passage for conveying combustion gases to the
atmosphere.
heating value: Amount of heat produced by combustion of a unit
quantity of solid or liquid fuel; determined in the labora-
tory at constant volume in an oxygen bomb calorimeter.
housing unit: Apartment, house, group of rooms, or a single room
occupied or intended for occupancy as separate living
quarters.
lignite: Brown, noncaking woody coal with high moisture and low
heating value. It is usually mined in Texas and North
Dakota.
national emission burden: Ratio of annual emissions from a
specific source to the total national emissions from all
stationary sources.
overfeed: Method of feeding solid fuel to a fuel bed where the
fresh fuel is charged to the top of the fuel bed.
overfire: Portion of the combustion air which enters the combus-
tion zone over the fuel bed to provide turbulence for smoke
reduction in hand- and stoker-fed coal combustion equipment.
plenum: Air space or chamber under pressure.
proximate analysis: Fuel analysis on the basis of percent fixed
carbon, volatile matter, moisture, and ash.
pyrolysis: Chemical decomposition by the application of heat.
130
-------
rank of coal: Method of classifying coal by chemical and physi-
cal properties.
representative source: Coal-fired residential combustion source
defined for use in calculating source severity.
retort: Cast iron chamber in the shape of a cup or trough used
to devolatilize and ignite coal in a stoker-fed furnace or
boiler.
stoker: Mechanical device used to feed solid fuel to a combus-
tion unit.
source severity: Indication of the hazard potential of an emis-
sion source.
state emission burden: Ratio of annual emissions from a specific
source in any state to the total state emissions from all
stationary sources.
threshold limit value (TLV): Refers to airborne concentrations
of substances and represents conditions under which it is
believed that nearly all workers may be repeatedly exposed
day after day without adverse effect.
tuyeres: Slotted holes in the retort for directing combustion
air to the fuel bed of a coal-fired heating device.
ultimate analysis: Fuel analysis on the basis of elemental con-
tent; namely, carbon, hydrogen, oxygen, nitrogen, sulfur,
and ash.
underfeed: Method of feeding solid fuel to a fuel bed where the
fresh fuel is introduced from beneath the fuel bed.
underfire: Method of providing combustion air to a fuel bed by
forcing the air through the fuel bed from underneath.
warm-air furnace: Closed vessel in which fuel is burned to heat
room air.
wind box: Enclosure around a stoker which directs combustion air
through the retort.
worm-feed mechanism: Motor-driven screw which conveys solid
fuel from storage and discharges the fuel into the retort
of a combustion operation.
131
-------
CONVERSION FACTORS AND METRIC PREFIXES (85)
To convert from
Degree Celsium (°C)
Kelvin (K)
Gram (g)
Gram/second (g/s)
Joule (J)
Kilogram (kg)
Kilogram (kg)
Kilogram/meter3 (kg/m3)
Kilometer2 (km2)
Meter (m)
Meter (m)
Meter3 (m3)
Metric ton
Pascal (Pa)
CONVERSION FACTORS
To
Degree Fahrenheit (°F)
Degree Celsius (°C)
Found-mass
Pounds/hour
British thermal unit (Btu)
Pound mass (Ib mass
avoirdupois)
Ton (short, 2,000 Ib mass)
Lb mass/foot3
Mile2
Foot
Inch
Foot3
Pound-mass
Pound-force/inch2 (psi)
Multiply by
°F
tn.
1-8 t0(, + 32
= tR - 273.15
2.205 x 10~3
7.930
9.479 x 10-**
2.204
1.102 x 10~3
6.243 x 10~2
2.591
3.281
3.937 x 101
3.531 x 101
2.205 x 103
1.450 x 10-*
Prefix Symbol
METRIC PREFIXES
Multiplication
factor
Example
Giga
Mega
Kilo
Milli
Micro
Pico
G
M
k
m
y
P
IO9
IO6
IO3
io-3
10~6
io-12
1 Gg =
1 MJ =
1 kPa =
1 mg =
1 pm »
1 pg =
1 x IO9 grams
1 x IO6 joules
1 x IO3 pascals
1 x 10"3 gram
1 x 10"6 meter
1 x 10"12 gram
(85) Metric Practice Guide. ASTM Designation E 380-74, American
Society for Testing and Materials, Philadelphia,
Pennsylvania, November 1974. 34 pp.
132
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-79-019a
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
SOURCE ASSESSMENT: Residential Combustion
of Coal
5. REPORT DATE
January 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
D. G. DeAngelis and R. B. Reznik
8. PERFORMING ORGANIZATION REPORT NO,
MRC-DA-878
10. PROGRAM ELEMENT NO.
1AB015
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
11. CONTRACT/GRANT NO.
68-02-1874
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 11/76 - 11/78
14. SPONSORING AGENCY CODE
EPA/600/13
,5. SUPPLEMENTARY NOTES jERL-RTP project officer is Ronald A. Venezia, MD-62, 919/541-
2547. Earlier Source Assessment reports are in the EPA-600/2-76-032, -77-107,
and -78-004 series.
IB. ABSTRACT The peporj. summarizes the assessment of air emissions from the residen-
tial combustion of anthracite, bituminous , and lignite coals, with emphasis on bi-
tuminous coals. Approximately 2.6 million metric tons of coal were burned as a
primary source of heat in an estimated 493,018 housing units in 1974. Geographical
distribution of coal-fired heating devices is related to the location of major coal
fields. Stoker-fed boilers and warm-air furnaces are currently being marketed for
burning coal as a primary source of heat in residential structures; however, hand-
fed units and room heaters also exist. Emissions from these units include particu-
lates, SOx, NOx, CO, hydrocarbons, poly cyclic organic material (POM), and trace
elements. The severities of these emissions were assessed for an average source.
Emissions of POMs were found to have a severity of 2.6 for combustion of bitumin-
ous coal; the remaining emissions had severities of 0.05 or less. A special assess-
ment of the environmental impact of an array of 100 houses burning coal indicates
the potential for a 30-fold increase in the severities of associated emissions.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
pollution
Assessments
Coal
Combustion
Heating
Sulfur Oxides
f^hemical Analysis
Nitrogen Oxides
Carbon Monoxide
Hydrocarbons
Trace Elements
Polycyclic Com-
pounds
Pollution Control
Stationary Sources
Residential Heating
Polycyclic Organic
Material
13B
14B
21D
21B
13A
07B
07D
07C
fgTDISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
143
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
rpA Form 2220-1 (»-73)
133
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