AP42B
AP-42
Supplement B
September 1988
SUPPLEMENT B
TO
COMPILATION
OF
AIR POLLUTANT
EMISSION FACTORS
Volume I:
Stationary Point
And Area Sources
FOR REFERENCE
Do Not Take From This Room
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office Of Air And Radiation K,
Office Of Air Quality Planning And Standards ^ ,-
Research Triangle Park, North Carolina 27711 k<° \°^
oCT
^ (0s
V
I}'**0'
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'I'hi- report ha? been rc\ iewed l>> The Office ()(' \ir Oualilx Planning \nd Standards. I'.S. Em iron mental
Protection \fieiic\. and has horn appnncd for piihlicution. Mention of trade names or commercial products
U not intended to con-lilute eudor>cmcnt or recommendalion for use.
\ (diuiic I
Supplement II
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INSTRUCTIONS FOR INSERTING SUPPLEMENT B
INTO AP-42
Pp. iii and iv replace same. New Publications in Series.
Pp. v through viii replace same. New Contents.
Pp. 1.1-1 through 1.1-17 replace same. Minor Revision.
Pp. 1.2-1 through 1.2-7 replace same. Minor Revision.
Pp. 1.10-1 through 1.10-5 replace 1.10-1 through 1.10-7. Major Revision.
Pp. 1.11-1 through 1.11-7 replace 1.11-1 and 2. Major Revision.
Pp. 2.1-1 through 2.1-10 replace 2.1-1 through 2.1-6. Major Revision.
Pp. 2.5-1 through 2.5-6 replace 2.5-1 through 2.5-3. Major Revision.
Pp. 4.2.2.7-1 through 4.2.2.7-8 replace 4.2.2.7-1 through 4.2.2.7-3. Major
Revision.
Add pp. 4.12-1 through 4.12-10. New Section.
Pp. 5.15-1 through 5.15-5 replace 5.15-1 through 5.15-4. Major Revision.
Pp. 6.4-1 through 6.4-15 replace 6.4-1 through 6.4-7. Major Revision.
Pp. 8.15-3 through 8.15-5 replace same. Editorial Change.
Pp. 8.19.2-1 through 8.19.2-6 replace same. Minor Revision.
Pp. 8.24-1 through 8.24-11 replace same. Minor Revision.
Add pp. 11-1 and 2. Editorial Change.
Pp. 11.1-1 through 11.1-11 replace 11.1-1 through 11.1-5. Major Revision.
Pp. 11.2.1-1 through 11.2.1-8 replace 11.2.1-1 through 11.2.1-6. Major
Revision.
Pp. 11.2.3-1 through 11.2.3-5 replace 11.2.3-1 through 11.2.3-6. Major
Revision.
Pp. 11.2.6-1 through 11.2.6-5 replace same. Major Revision.
Add pp. 11.2.7-1 through 11.2.7-15. New Section.
Add pp. C.3-1 and 2. New Appendix.
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PUBLICATIONS IN SERIES
Issue
COMPILATION OF AIR POLLUTANT EMISSION FACTORS (Fourth Edition)
SUPPLEMENT A
Introduction
Section 1.1
1.2
1.3
1.4
. 1.6
1.7
5.16
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.10
7.11
8.1
8.3
8.6
8.10
8.13
8.15
8.19.2
8.22
8.24
10.1
11.2.6
Appendix C.I
Appendix C.2
9/85
10/86
Bituminous And Subbituminous Coal Combustion
Anthracite Coal Combustion
Fuel Oil Combustion
Natural Gas Combustion
Wood Waste Combustion In Boilers
Lignite Combustion
Sodium Carbonate
Primary Aluminum Production
Coke Production
Primary Copper Smelting
Ferroalloy Production
Iron And Steel Production
Primary Lead Smelting
Zinc Smelting
Secondary Aluminum Operations
Gray Iron Foundries
Secondary Lead Smelting
Asphaltic Concrete Plants
Bricks And Related Clay Products
Portland Cement Manufacturing
Concrete Batching
Glass Manufacturing
Lime Manufacturing
Crushed Stone Processing
Taconite Ore Processing
Western Surface Coal Mining
Chemical Wood Pulping
Industrial Paved Roads
Particle Size Distribution Data And Sized Emission
Factors For Selected Sources
Generalized Particle Size Distributions
SUPPLEMENT B
Section 1.1
1.2
1.10
1.11
2.1
2.5
4.2
4.12
5.15
6.4
9/88
Bituminous And Subbituminous Coal Combustion
Anthracite Coal Combustion
Residential Wood Stoves
Waste Oil Combustion
Refuse Combustion
Sewage Sludge Incineration
Surface Coating
Polyester Resin Plastics Product Fabrication
Soap And Detergents
Grain Elevators And Processing Plants
iii
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Section 8.15 Lime Manufacturing
8.19.2 Crushed Stone Processing
8.24 Western Surface Coal Mining
11.1 Wildfires And Prescribed Burning
11.2.1 Unpaved Roads
11.2.3 Aggregate Handling And Storage Piles
11.2.6 Industrial Paved Roads
11.2.7 Industrial Wind Erosion
Appendix C.3 Silt Analysis Procedures
iv
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CONTENTS
Page
INTRODUCTION 1
1. EXTERNAL COMBUSTION SOURCES 1.1-1
1.1 Bituminous Coal Combustion 1.1-1
1.2 Anthracite Coal Combustion 1.2-1
1.3 Fuel Oil Combustion 1.3-1
1.4 Natural Gas Combustion 1.4-1
1.5 Liquified Petroleum Gas Combustion 1.5-1
1.6 Wood Waste Combustion In Boilers 1.6-1
1.7 Lignite Combustion 1.7-1
1.6 Bagasse Combustion In Sugar Mills 1.8-1
1.9 Residential Fireplaces 1.9-1
1.10 Residential Wood Stoves 1.10-1
1.11 Waste Oil Combustion 1.11-1
2. SOLID WASTE DISPOSAL 2.0-1
2*1 Refuse Combustion 2.1-1
2.2 Automobile Body Incineration 2.2-1
2.3 Conical Burners 2.3-1
2.4 Open Burning 2.4-1
2.5 Sewage Sludge Incineration 2.5-1
3. STATIONARY INTERNAL COMBUSTION SOURCES 3.0-1
Glossary Of Terms Vol. II
Highway Vehicles Vol. II
Off Highway Mobile Sources Vol. II
3.1 Off Highway Stationary Sources 3.1-1
4. EVAPORATION LOSS SOURCES 4.1-1
4.1 Dry Cleaning 4.1-1
4.2 Surface Coating 4.2-1
4.3 Storage Of Organic Liquids 4.3-1
4.4 Transportation And Marketing Of Petroleum Liquids 4.4-1
4.5 Cutback Asphalt, Emulsified Asphalt And Asphalt Cement .. 4.5-1
4.6 Solvent Deg teas ing 4.6-1
4.7 Waste Solvent Reclamation 4.7-1
4.8 Tank And Drum Cleaning 4.8-1
4.9 Graphic Arts 4.9-1
4.10 Commercial/Consumer Solvent Use 4.10-1
4.11 Textile Fabric Printing 4.11-1
5. CHEMICAL PROCESS INDUSTRY 5.1-1
5.1 Adipic Acid 5.1-1
5.2 Synthetic Ammonia 5.2-1
5.3 Carbon Black 5.3-1
5.4 Charcoal 5.4-1
5.5 Chlor-Alkali 5.5-1
5.6 Explosives 5.6-1
5.7 Hydrochloric Acid 5.7-1
5.8 Hydrofluoric Acid 5.8-1
5.9 Nitric Acid 5.9-1
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Page
5.10 Paint And Varnish 5.10-1
5.11 Phosphoric Acid 5.11-1
5.12 Phthalic Anhydride 5.12-1
5.13 Plastics 5.13-1
5.14 Printing Ink 5.14-1
5.15 Soap And Detergents 5.15-1
5.16 Sodium Carbonate 5.16-1
5.17 Sulfuric Acid 5.17-1
5.18 Sulfur Recovery 5.18-1
5.19 Synthetic Fibers 5.19-1
5.20 Synthetic Rubber 5.20-1
5.21 Terephthalic Acid 5.21-1
5.22 Lead Alkyl . 5.22-1
5.23 Pharmaceuticals Production 5.23-1
5.24 Maleic Anhydride 5.24-1
6. FOOD AND AGRICULTURAL INDUSTRY 6.1-1
6.1 Alfalfa Dehydrating 6.1-1
6.2 Coffee Roasting 6.2-1
6.3 Cotton Ginning 6.3-1
6.4 Grain Elevators And Processing Plants 6.4-1
6.5 Fermentation 6.5-1
6.6 Fish Processing 6.6-1
6.7 Meat Smokehouses 6.7-1
6.8 Ammonium Nitrate Fertilizers 6.8-1
6.9 Orchard Heaters 6.9-1
6.10 Phosphate Fertilizers 6.10-1
6.11 Starch Manufacturing 6.11-1
6.12 Sugar Cane Processing 6.12-1
6.13 Bread Baking 6.13-1
6,14 Urea 6.14-1
6.15 Beef Cattle Feedlots 6.15-1
6.16 Defoliation And Harvesting Of Cotton 6.16-1
6.17 Harvesting Of Grain 6.17-1
6.18 Ammonium Sulfate 6.18-1
7. METALLURGICAL INDUSTRY 7.1-1
7.1 Primary Aluminum Production 7.1-1
7.2 Coke Production 7.2-1
7.3 Primary Copper Smelting 7.3-1
7.4 Ferroalloy Production 7.4-1
7.5 Iron And Steel Production 7.5-1
7.6 Primary Lead Smelting 7.6-1
7.7 Zinc Smelting 7.7-1
7.8 Secondary Aluminum Operations 7.8-1
7.9 Secondary Copper Smelting And Alloying 7.9-1
7.10 Gray Iron Foundries 7.10-1
7.11 Secondary Lead Smelting 7.11-1
7.12 Secondary Magnesium Smelting 7.12-1
7.13 Steel Foundries 7.13-1
7.14 Secondary Zinc Processing ..., 7.14-1
7.15 Storage Battery Production 7.15-1
vi
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Page
7.16 Lead Oxide And Pigment Production 7.16-1
7.17 Miscellaneous Lead Products 7.17-1
7.18 Leadbearing Ore Crushing And Grinding 7.18-1
8. MINERAL PRODUCTS INDUSTRY 8.1-1
8.1 Asphaltic Concrete Plants 8.1-1
8.2 Asphalt Roofing 8.2-1
8.3 Bricks And Related Clay Products 8.3-1
8.4 Calcium Carbide Manufacturing 8.4-1
8.5 Castable Refractories 8.5-1
8.6 Portland Cement Manufacturing 8.6-1
8.7 Ceramic Clay Manufacturing 8.7-1
8.8 Clay And Fly Ash Sintering 8.8-1
8.9 Coal Cleaning 8.9-1
8.10 Concrete Batching 8.10-1
8.11 Glass Fiber Manufacturing 8.11-1
8.12 Frit Manufacturing 8.12-1
8.13 Glass Manufacturing 8.13-1
8.14 Gypsum Manufacturing 8.14-1
8.15 Lime Manufacturing 8.15-1
8.16 Mineral Wool Manufacturing » 8.16-1
8.17 Perlite Manufacturing 8.17-1
8.18 Phosphate Rock Processing 8.18-1
8.19 Construction Aggregate Processing 8.19-1
8.20 [Reserved] 8.20-1
8.21 Coal Conversion 8.21-1
8.22 Taconite Ore Processing 8.22-1
8.23 Metallic Minerals Processing 8.23-1
8.24 Western Surface Coal Mining 8.24-1
9. PETROLEUM INDUSTRY 9.1-1
9.1 Petroleum Refining 9.1-1
9.2 Natural Gas Processing 9.2-1
10. WOOD PRODUCTS INDUSTRY 10.1-1
10.1 Chemical Wood Pulping 10.1-1
10.2 Pulpboard '.' 10.2-1
10.3 Plywood Veneer And Layout Operations 10.3-1
10.4 Woodworking Waste Collection Operations 10.4-1
11. MISCELLANEOUS SOURCES 11.1-1
11.1 Wildfires And Prescribed Burning 11.1-1
11.2 Fugitive Dust Sources 11.2-1
11.3 Explosives Detonation 11.3-1
APPENDIX A Miscellaneous Data And Conversion Factors A-l
APPENDIX B (Reserved For Future Use)
APPENDIX C.I Particle Size Distribution Data And Sized Emission
Factors For Selected Sources C.l-1
vii
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Page
APPENDIX C.2 Generalized Particle Size Distributions C.2-1
APPENDIX C.3 Silt Analysis Procedures C.3-1
viii
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1.1 BITUMINOUS AND SUBBITUMINOUS COAL COMBUSTION
1.1.1 General 1
Coal is a complex combination of organic matter and inorganic ash formed
over eons from successive layers of fallen vegetation. Coal types are broadly
classified as anthracite, bituminous, subbituminous or lignite, and classifica-
tion is made by heating values and amounts of fixed carbon, volatile matter,
ash, sulfur and moisture. Formulas for differentiating coals based on these
properties are given in Reference 1. See Sections 1.2 and 1.7 for discussions
of anthracite and lignite, respectively.
There are two major coal combustion techniques, suspension firing and
grate firing. Suspension firing is the primary combustion mechanism in pulver-
ized coal and cyclone systems. Grate firing is the primary mechanism In under-
feed and overfeed stokers. Both mechanisms are employed in spreader stokers.
Pulverized coal furnaces are used primarily in utility and large industrial
boilers. In these systems, the coal is pulverized in a mill to the consistency
of talcum powder (i. e., at least 70 percent of the particles will pass through
a 200 mesh sieve). The pulverized coal Is generally entrained in primary air
before being fed through the burners to the combustion chamber, where It Is
fired in suspension. Pulverized coal furnaces are classified as either dry or
wet bottom, depending on the ash removal technique. Dry bottom furnaces fire
coals with high ash fusion temperatures, and dry ash removal techniques are
used. In wet bottom (slag tap) furnaces, coals with low ash fusion tempera-
tures are used, and molten ash is drained from the bottom of the furnace.
Pulverized coal furnaces are further classified by the firing position of the
burners, i. e., single (front or rear) wall, horizontally opposed, vertical,
tangential (corner fired), turbo or arch fired.
Cyclone furnaces burn low ash fusion temperature coal crushed to a A mesh
size. The coal is fed tangentially, with primary air, to a horizontal cylin-
drical combustion chamber. In this chamber, small coal particles are burned
in suspension, while the larger particles are forced against the outer wall.
Because of the high temperatures developed in the relatively small furnace
volume, and because of the low fusion temperature of the coal ash, much of the
ash forms a liquid slag which Is drained from the bottom of the furnace through
a slag tap opening. Cyclone furnaces are used mostly in utility and large
industrial applications.
In spreader stokers, a flipping mechanism throws the coal into the furnace
and onto a moving fuel bed. Combustion occurs partly in suspension and partly
on the grate. Because of significant carbon In the particulate, flyash reln-
jection from mechanical collectors is commonly employed to improve boiler
efficiency. Ash residue in the fuel bed is deposited In a receiving pit at the
end of the grate.
9/88 External Combustion Sources 1.1-1
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In overfeed stokers, coal is fed onto a traveling or vibrating grate, and
it burns on the fuel bed as it progresses through the furnace. Ash particles
fall into an ash pit at the rear of the stoker. The term "overfeed" applies
because the coal is fed onto the moving grate under an adjustable gate. Con-
versely, in "underfeed" stokers, coal is fed into the firing zone from under-
neath by mechanical rams or screw conveyers. The coal moves in a channel,
known as a retort, from which it is forced upward, spilling over the top of
each side to form and to feed the fuel bed. Combustion is completed by the
time the bed reaches the side dump grates from which the ash is discharged to
shallow pits. Underfeed stokers include single retort units and multiple
retort units, the latter having several retorts side by side.
1.1.2 Emissions And Controls
The major pollutants of concern from external coal combustion are partic-
ulate, sulfur oxides and nitrogen oxides. Some unburnt combustibles, including
numerous organic compounds and carbon monoxide, are generally emitted even
under proper boiler operating conditions.
Parttculate2~4 - partlculate composition and emission levels are a complex
function of firing configuration, boiler operation and coal properties. In
pulverized coal systems, combustion is almost complete, and thus participate
largely comprises inorganic ash residue. In wet bottom pulverized coal units
and cyclones, the quantity of ash leaving the boiler is less than in dry bottom
units, since some of the ash liquifies, collects on the furnace walls, and
drains from the furnace bottom as molten slag. To Increase the fraction of ash
drawn off as wet slag, and thus to reduce the flyash disposal problem, flyash
may be reinjected from collection equipment into slag tap systems. Dry bottom
unit ash may also be retnjected into wet bottom boilers for the same purpose.
Because a mixture of fine and coarse coal particles is fired in spreader
stokers, significant unburnt carbon can be present in the particulate. To
improve boiler efficiency, flyash from collection devices (typically multiple
cyclones) is sometimes reinjected into spreader stoker furnaces. This prac-
tice can dramatically increase the particulate loading at the boiler outlet
and, to a lesser extent, at the mechanical collector outlet. Flyash can also
be reinjected from the boiler, air heater and economizer dust hoppers. Flyash
reinjectlon from these hoppers does not increase particulate loadings nearly so
much as from multiple cyclones.-*
Uncontrolled overfeed and underfeed stokers emit considerably less particu-
late than do pulverized coal units and spreader stokers, since combustion takes
place in a relatively quiescent fuel bed. Flyash reinjectlon is not practiced
in these kinds of stokers.
Other variables than firing configuration and flyash relnjection can
affect emissions from stokers. Particulate loadings will often increase as
load increases (especially as full load is approached) and with sudden load
changes. Similarly, particulate can increase as the ash and fines contents
increase. ("Fines", in this context, are coal particles smaller than about 1.6
millimeters, or one sixteenth inch, in diameter.) Conversely, particulate can
be reduced significantly when overftre air pressures are increased.''
1.1-4 EMISSION FACTORS 9/88
-------
The primary kinds of partlculate control devices used for coal combustion
Include multiple cyclones, electrostatic preclpitators, fabric filters (bag-
houses) and scrubbers. Some measure of control will even result from ash
settling In boiler/air heater/economizer dust hoppers, large breeches and chim-
ney bases. To the extent possible from the existing data base, the effects of
such settling are reflected In the emission factors In Table 1.1-1.
Electrostatic preclpltators (ESP) are the most common high efficiency
control device used on pulverized coal and cyclone units, and they are being
used Increasingly on stokers. Generally, ESP collection efficiencies are a
function of collection plate area per volumetric flow rate of flue gas through
the device. Partlculate control efficiencies of 99.9 weight percent are
obtainable with ESPs. Fabric filters have recently seen Increased use In both
utility and Industrial applications, generally effecting about 99.8 percent
efficiency. An advantage of fabric filters Is that they are unaffected by high
flyash resistivities associated with low sulfur coals. ESPs located after air
preheaters (1. e., cold side precipttators) may operate at significantly reduced
efficiencies when low sulfur coal is fired. Scrubbers are also used to control
particulate, although their primary use is to control sulfur oxides. One draw-
back of scrubbers is the high energy requirement to achieve control efficiencies
comparable to those of ESPs and baghouses.2
Mechanical collectors, generally multiple cyclones, are the primary means
of control on many stokers and are sometimes Installed upsteam of high effi-
ciency control devices in order to reduce the ash collection burden. Depending
on application and design, multiple cyclone efficiencies can vary tremendously.
Where cyclone design flow rates are not attained (which is common with under-
feed and overfeed stokers), these devices may be only marginally effective and
may prove little better In reducing particulate than large breeching. Con-
versely, well designed multiple cyclones, operating at the required flow rates,
can achieve collection efficiencies on spreader stokers and overfeed stokers
of 90 to 95 percent. Even higher collection efficiencies are obtainable on
spreader stokers with reinjected flyash, because of the larger particle sizes
and increased particulate loading reaching the controls.^~6
Sulfur Oxides7~9 _ Gaseous sulfur oxides from external coal combustion
are largely sulfur dioxide (802) and much less quantity of sulfur trloxlde
(803) and gaseous sulfates. These compounds form as the organic and pyritlc
sulfur in the coal Is oxidized during the combustion process. On average, 98
percent of the sulfur present In bituminous coal will be emitted as gaseous
sulfur oxides, whereas somewhat less will be emitted when subbituminous coal
Is fired. The more alkaline nature of the ash In some subbituminous coal
causes some of the sulfur to react to form various sulfate salts that are
retained In the boiler or In the flyash. Generally, boiler size, firing con-
figuration and boiler operations have little effect on the percent conversion
of fuel sulfur to sulfur oxides.
Several techniques are used to reduce sulfur oxides from coal combustion.
One way is to switch to lower sulfur coals, since sulfur oxide emissions are
proportional to the sulfur content of the coal. This alternative may not be
possible where lower sulfur coal is not readily available or where a different
grade of coal can not be satisfactorily fired. In some cases, various cleaning
processes may be employed to reduce the fuel sulfur content. Physical coal
cleaning removes mineral sulfur such as pyrite but is not effective in removing
9/88 External Combustion Sources 1.1-5
-------
organic sulfur. Chemical cleaning and solvent refining processes are being
developed to remove organic sulfur. '
Many flue gas desulfurization techniques can remove sulfur oxides formed
during combustion. Flue gases can be treated through wet, semidry or dry
desulfurization processes of either the throwaway type, in which all waste
streams are discarded, or the recovery (regenerable) type, in which the SOX
absorbent is regenerated and reused. To date, wet systems are the most com-
monly applied. Wet systems generally use alkali slurries as the SOx absorbent
medium and can be designed to remove well in excess of 90 percent of the in-
coming S0x« Particulate reduction of up to 99 percent is also possible with
wet scrubbers, but flyash is often collected by upsteam ESPs or baghouses, to
avoid erosion of the desulfurization equipment and possible interference with
the process reactions.^ Also, the volume of scrubber sludge is reduced with
separate flyash removal, and contamination of the reagents and byproducts is
prevented. References 7 and 8 give more details on scrubbing and other SOX
removal techniques.
Nitrogen Oxides 10~11 - Nitrogen oxides (NOX) emissions from coal
combustion are primarily nitrogen oxide (NO). Only a few volume percent are
nitrogen dioxide (N02). NO results from thermal fixation of atmospheric nitro-
gen in the combustion flame and from oxidation of nitrogen bound in the coal.
Typically, only 20 to 60 percent of the fuel nitrogen is converted to nitrogen
oxides. Bituminous and subbltumlnous coals usually contain from 0.5 to 2
weight percent nitrogen, present mainly In aromatic ring structures. Fuel
nitrogen can account for up to 80 percent of total NO^ from coal combustion.
A number of combustion modifications can be made to reduce NOX emissions
from boilers. Low excess air (LEA) firing Is the most widespread control
modification, because it can be practiced in both old and new units and In all
sizes of boilers. LEA firing is easy to implement and has the added advantage
of Increasing fuel use efficiency. LEA firing is generally effective only
above 20 percent excess air for pulverized coal units and above 30 percent
excess air for stokers. Below these levels, the NOx reduction from decreased 02
availability is offset by Increased NOX because of "increased flame temperature.
Another NOX reduction technique is simply to switch to a coal having a lower
nitrogen content, although many boilers may not properly fire coals of different
properties.
Off-stoichiometric (staged) combustion is also an effective means of
controlling NOX from coal fired equipment. This can be achieved by using
overfire air or low NOjj burners designed to stage combustion in the flame zone.
Other NOx reduction techniques Include flue gas recirculatlon, load reduction,
and steam or water injection. However, these techniques are not very effective
for use on coal fired equipment because of the fuel nitrogen effect. Ammonia
Injection is another technique which can be used, but it Is costly. The net
reduction of NOX from any of these techniques or combinations thereof varies
considerably with boiler type, coal properties and existing operating practices.
Typical reductions will range from 10 to 60 percent. References 10 and 60
should be consulted for a detailed discussion of each of these NOx reduction
techniques. To date, flue gas treatment is not used to reduce nitrogen oxide
emissions because of its higher cost.
ia_6 EMISSION FACTORS 9/88
-------
Volatile Organic Compounds And Carbon Monoxide - Volatile organic compounds
(VOC) and carbon monoxide (CO)'are unburnt gaseous combustibles which generally
are emitted in quite small amounts. However, during startups, temporary upsets
or other conditions preventing complete combustion, unburnt combustible emis-
sions may increase dramatically. VOC and CO emissions per unit of fuel fired
are normally lower from pulverized coal or cyclone furnaces than from smaller
stokers and handfired units where operating conditions are not so well con-
trolled. Measures used for NOX control can Increase CO emissions, so to reduce
the risk of explosion, such measures are applied only to the point at which CO
In the flue gas reaches a maximum of about 200 parts per million. Other than
maintaining proper combustion conditions, control measures are not applied to
control VOC and CO.
Emission Factors And References - Emission factors for several pollutants
are presented in Table 1.1-1, and factor ratings and references are presented
in Table 1.1-2. The factors for uncontrolled underfeed stokers and hand fired
units also may be applied to hot air furnaces. Tables 1,. 1-3 through 1.1-8
present cumulative size distribution data and size specific emission factors
for particulate emissions from the combustion sources discussed above. Uncon-
trolled and controlled size specific emission factors are presented in Figures
1.1-1 through 1.1-6.
External Combustion Sources 1.1-7
-------
TABLE 1.1-3. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC EMISSION
FACTORS FOR DRY BOTTOM BOILERS BURNING PULVERIZED BITUMINOUS COALa
EMISSION FACTOR RATING:
C (uncontrolled)
u (scrubber and ESP controlled
E (multiple cyclone and baghouse)
Particle «l»eh
(UK)
13
10
6
2.!
1.25
1.00
0.625
TOTAL
Cumulative •«• I <_ stated mil*
Uncontrolled
32
23
17
6
2
2
1
100
Cone rolled
Multiple
cyclone
54
29
14
3
1
1
1
100
Scrubber
81
71
62
51
35
31
20
too
ESP
79
67
50
29
17
14
12
100
Beg home
97
92
77
53
31
25
14
100
Cumulative emlaaion fectorC (kg/Kg (lb/ton) coel, at fired]
Uncontrolled
1.6A
(3.2A)
LISA
(2.3A)
0.»5A
(1.7A)
0.30 A
(0.6A)
0.10A
(0.2A)
0.10A
(0.2A)
0.05A
(0.10)
5A
(10A)
Controlled11
Multiple
cyclone
0.54A
(1.08A)
0.29A
(O.S8A)
0.14A
(0.28A)
0.03A
(0.06A)
0.01A
(0.02A)
0.01A
(0.02A)
0.0 1A
(0.02A)
1A
(2A)
Scrubber
0.24A
(0.48A)
0.21A
(0.42A)
0.19A
(0.38A)
0.15A
(0.3A)
0.1IA
(0.22A)
0.09A
(0.18A)
0.06A
(0.12A)
0.3A
(0.6A)
ESP
0.032A
(0.06A)
0.027*
(0.05A)
0.020A
(0.04A)
0.012A
(0.02A)
0.007A
(0.01A)
0.006A
(0.01A)
0.005A
(0.01A)
0.04A
(0.08 A)
Bag house
0.010A
(0.02A)
0.009A
(0.02A)
0.008*
(0.02A)
0.005A
(0.01A)
0.003A
(0.006A)
0.003*
(0.006*)
O.OOIA
(0.002A)
0.01A
(0.02A)
Heference 61. ESP - electroetetlc preclpltator.
•bpreaeed ae aerodynamic equivalent diameter.
CA - eaal ««h velght X, «• Uted.
'Estimated control efficiency for multiple cyclone, 801; icrubber, 94t;
ESP, 99.21; baghouae, 99.81.
I .
2.QA
1.8A
1.6A
1.4A
1.2A
l.OA
0.8A
0.6A
0.4A
0.2A
0
Scrubber
Bdghouse
Uncontrolled
Multiple cyclone
l.OA
0.6A
0.4A
0.2A
0.1A
0.06A
0.04A
0.02A
Ol I.
O C
01 —
•5.3
.4 .6 i 2 4 6 10
Particle diameter (um)
20
40 60 100
0.01A —I
0.1A
i.
0.06A §
u
0.04A £
3
O
-C -
or
0.03A 5.
c
0.01A 2.
0.006A >.
0.004A S.
•a
0.002A I
c
O.OOIA
Figure 1.1-1,
1.1-8
Cumulative size specific emission factors for dry bottom
boilers burning pulverized bituminous coal.
EMISSION FACTORS
9/88
-------
TABLE 1.1-4.
CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC EMISSION
FACTORS FOR WET BOTTOM BOILERS BURNING PULVERIZED BITUMINOUS C'OALa
EMISSION FACTOR RATING: E
Particle slzeb
(u»)
IS
10
6
2.5
1.25
1.00
0.625
TOTAL
emulative naa. X <_ atateri alze
Uncontrolled
40
37
33
21
6
4
2
100
Controlled
Multiple
cyclone
99
93
84
61
31
19
e
100
ESP
83
75
63
40
17
8
e
100
Cumulative enlaalon factorc (kg/Hg (Ib/ton) coal, aa fired]
Uncontrolled
1.4A (2.8A)
1.30 A (2.6A)
1.16A (2.32A)
0.74A (1.48A)
0.21A (0.42A)
0.14A (0.28A)
0.07A (0.14A)
3.5A (7.0A)
Controlled11
Multiple cyclone
0.69A (1.38A)
0.6SA (1.3A)
0.59 A (1.18A)
0.43A (0.86A)
0.22A (0.44A)
0.1 3A (0.26A)
e
0.7A <1.4A)
ESP
0.023A (0.046A)
0.021A (0.042A)
0.018A (0.036A)
0.011A (0.022A)
0.005A (0.01A)
0.002A (0.004A)
e
0.028A (0.056A)
'Reference 61. ESP - electrostatic preclpttator.
^Expressed as aerodynamic equivalent dimeter.
CA - coal ash weight Z, as fired.
HF,fltl«ated control efficiency for multiple cyclone. 801; ESP, 99.2t
elnsuffIclent data.
f— (71
3.(jA
2.UA
2.1A
1.4A
0. /OA
.2
.4 .6 1
246 10
Particle diameter dun)
40 faO 100
1A
06A
t_
o
04A *_
-o
02A § "
0.01A
•o >—
0; m
*— O
006Ao "
~s
004A o 5
0.002A
0.001A
Figure 1.1-2.
Cumulative size specific emission factors for wet bottom
boilers burning pulverized bituminous coal
9/88
External Combustion Sources
1.1-9
-------
TABLE 1.1-5.
CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC EMISSION
FACTORS FOR CYCLONE FURNACES BURNING BITUMINOUS COAL3
EMISSION FACTOR RATING: E
Particle size0
15
10
6
2.5
1.25
1.00
0.625
TOTAL
Cumulative mass X < stated size
Uncontrolled
33
13
8
0
0
0
0
100
Controlled
Scrubber
95
94
93
92
85
82
d
100
ESP
90
68
56
36
22
17
d
100
Cumulative emission factorc [kg/Kg (Ib/ton) coal, as fired]
Uncontrolled
0.33A (0.66A)
0.13A (0.26A)
0.08A (0.16A)
0 (0)
0 (0)
0 (0)
0 (0)
1A (2A)
Controlled6
Scrubber
0.057A (0.114A)
0.056A (0.112A)
0.056A (O.U2A)
0.055A (0.11A)
0.051A (O.IOA)
0.049A (O.IOA)
d
0.06A (0.12A)
ESP
0.0064A (0.013A)
0.0054A (0.011A)
0.0045A (0.009A)
0.0029A (0.006A)
0.0018A (0.004A)
O.OOUA (0.003A)
d
0.008A (O.OlfiA)
aReference 61. ESP - electrostatic preclpttator.
''Expressed as aerodynamic equivalent diameter.
CA - coal ash weight %, as fired.
dlnsufficlent data.
•Estimated control efficiency for scrubber, 94%; ESP, 99.2*.
8 -
US
^- (J
•go,
Si
e.
l.QA
0.9A
C.8A
0.7A
0.6A
0.5A
0.4A
Q.3A
0.2A
0.1A
0
i i i i i 11
.1 .2 .4 .6 1 2 46 10
Particle diameter (pm)
Uncontrolled
O.IOA
O.ObA
0.04A
0.02A
0.01A
0.006A
Q.004A
0.002A
0.001A
se
•— *D
e .
c **j
o o
O- O>
20
40 60 100
Figure 1.1-3.
Cumulative size specific emission factors for
furnaces burning bituminous coal
1.1-10
EMISSION FACTOKS
9/88
-------
TABLE 1.1-6.
CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC EMISSION
FACTORS FOR SPREADER STOKERS BURNING BITUMINOUS COAL3
EMISSION FACTOR RATING:
C (uncontrolled and controlled for
multiple cyclone without flyash
reinjection, and with baghouse)
E (multiple cyclone controlled with
flyash relnjectlon, and ESP
controlled)
Particle al«e°
(»•>
IS
10
6
2.5
1.25
1.00
0.625
TOTAL
Cumulative naaa X <. stated alze
Uncontrolled
28
20
U
7
5
5
4
100
Controlled
Multiple
cycionec
86
7}
51
8
2
2
1
100
Multiple
cyclone^
74
65
52
27
16
14
9
100
ESP
97
90
82
61
46
41
e
100
Baghouae
72
60
46
26
18
15
7
100
Uncontrolled
8.4
(16.8)
6.0
(12.0)
4.2
(8.4)
2.1
(4.2)
1.5
(5.0)
1.5
(3.0)
1.2
(2.4)
30.0
(60.0)
'Mg (Ib/ton) coal, aa ftr*d|
Controlled
Multiple
cyclonec
7.3
(14.6)
6.2
(12.4)
4.3
(8.6)
0.7
(1.4)
0.2
(0.4)
0.2
(0.4)
0.1
(0.2)
8.5
(ir.o)
Multiple
cyclone^
4.4
(8.8)
3.9
(7.8)
3.1
(6.2)
1.6
(3.2)
1.0
(2.0)
0.8
(1.6)
0.5
(1.0)
6.0
(12.0)
ESP
0.23
(0.46)
0.22
(0.44)
0.21)
(0.40)
0.15
(0.30)
0.11
(0.22)
0.10
(0.20)
e
0.24 '
(0.48)
Baghou.e
0.043
(0.086)
0.036
(0.072)
0.028
(0.056)
0.016
(0.032)
0.011
(0.022)
0.009
(0.018)
0.004
(0.008)
0.06f
(0.12)
^Expressed aa aerodynamic equivalent diameter.
cwith flyaeh relnjectlon.
^Without flyaah relnjectlon.
•Insufficient data.
'Efttfaated control efficiency for ESP, 99.21; baghouae, 99,8Z.
C <-
O £
2s
10
9
8
7
6
5
4
3
2
1
0
Multiple cyclone wi th
flyash relnjectlon
Multiple cyclone without
flydsh reinjection
.2
Baghoube
Uncontrolled
tSP
.4 .6
20
40 60 100
10.0
6.C —
131
4.o ~.-
O "*"
i -
C "°
O
2.0
1.0
0.6
0.4
0.2
0.1
0.10
0.06
0.04
0.02
0.01
0.006
0.004
0.002
0.001
Figure
1 2 4 6 10
Particle diameter (urn)
1.1-4. Cumulative size specific emission factors for spreader
stokers burning bituminous coal
9/88
External Combustion Sources
1.1-11
-------
TABLE 1.1-7. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC EMISSION
FACTORS FOR OVERFEED STOKERS BURNING BITUMINOUS COAL3
EMISSION FACTOR RATING: C (uncontrolled)
E (multiple cyclone controlled)
Particle sizeb
(um)
15
10
6
2.5
1.25
1.00
0.625
TOTAL
Cumulative mans I £ stated size
Uncontrolled
49
37
24
14
13
12
c
100
Multiple cyclone
controlled
60
55
49
43
39
39
16
100
Cumulative emission factor
[kg/Kg (Ib/ton) coal, as fired]
Uncontrolled
3.9 (7.8)
3.0 (6.0)
1.9 (3.8)
1.1 (2.2)
1.0 (2.0)
1.0 (2.0)
c
8.0 (16.0)
Multiple cyclone
controlled"1
2.7 (5.4)
2.5 (5.0)
2.2 (4.4)
1.9 (3.8)
1.8 (3.6)
1.8 (3.6)
0.7 (1.4)
4.5 (9.0)
"Reference 61.
^Expressed as aerodynamic equivalent diameter.
'Insufficient data.
^Estimated control efficiency for multiple cyclone, 80Z.
3
O -—•
8
7.2
6.4
4.8
4.0
3.2
2.4
1.6
O.B
0
Multiple
cyclone
10
-6.0
4.0
2.0
1.0
0.6
0.4
0.1
.1 .2 .4 .6 1 246 10
Particle diameter (uin)
20
40 60 100
u >.
>t Ct
o *•
0.2 £.2
Figure 1.1-5. Cumulative size specific emission factors for overfeed
stokers burning bituminous coal
1.1-12
EMISSION FACTORS
9/88
-------
TABLE 1.1-8. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC EMISSION
FACTORS FOR UNDERFEED STOKERS BURNING BITUMINOUS COALa
EMISSION FACTOR RATING: C
Particle alzeb
(un)
IS
10
6
2.5
1.25
1.00
0.625
TOTAL
Cumulative mass 7. <_ stated size
50
41
32
25
22
21
18
100
Uncontrolled cumulative ei
[kg/Mg (Ib/ton) coal,
3.8 (7.6)
3.1 (6.2)
2.4 (4.8)
1.9 (3.8)
1.7 (3.4)
1.6 (3.2)
1.4 (2.7)
7.5 (15.0)
nisalon factorc
as fired]
aReference 61.
^Expressed aa aerodynamic equivalent diameter.
cMay also be used Cor uncontrolled hand fired units.
10
9
8
S 7
i »: 3
• 5"
i* z
i
1
0
Particle diameter (\aa]
Figure 1.1-6. Cumulative size specific emission factors for underfeed
stokers burning bituminous coal.
9/88
External Combustion Sources
1.1-13
-------
References for Section 1.1
1. Steam, 38th Edition, Babcock and Wilcox, New York, 1975.
2. Control Techniques for Particulate Emissions from Stationary Sources,
Volume I, EPA-45073-81-005a, U. S. Environmental Protection Agency,
Research Triangle Park, NC, April 1981.
3. Ibidem, Volume II, EPA-450/3-81-0005b.
4. Electric Utility Steam Generating Units: Background Information for
Proposed Particulate Matter Emission Standard, EPA-450/2-78-006a, U. S.
Environmental Protection Agency, Research Triangle Park, NC, July 1978.
5. W. Axtman and M. A. Eleniewski, "Field Test Results of Eighteen Industrial
Coal Stoker Fired Boilers for Emission Control and Improved Efficiency",
Presented at the 74th Annual Meeting of the Air Pollution Control Asso-
ciation, Philadelphia, PA, June 1981.
6. Field Tests of Industrial Stoker Coal Fired Boilers for Emission Control
and Efficiency Improvement - Sites Ll-17, EPA-600/7-81-020a, U. S. Environ-
mental Protection Agency, Washington, DC, February 1981.
7. Control Techniques for Sulfur Dioxide Emissions from Stationary Sources,
2nd Edition, EPA-450/3-81-004, U. S. Environmental Protection Agency,
Research Triangle Park, NC, April 1981.
8. Electric Utility Steam Generating Units: Background Information for
Proposed SO? Emission Standards, EPA-450/2-78-007a, U. S. Environmental
Protection Agency, Research Triangle Park, NC, July 1978.
Environmental Protection Agency, Washington, DC, February 1981.
9. Carlo Castaldini and Meredith Angwin, Boiler Design and Operating Vari-
ables Affecting Uncontrolled Sulfur Emissions from Pulverized Coal Fired
Steam Generators, EPA-450/3-77-047, U. S. Environmental Protection Agency,
Research Triangle Park, NC, December 1977.
10. Control Techniques for Nitrogen Oxides Emissions from Stationary Sources,
2nd Edition, EPA-450/1-78-001, U. S. Environmental Protection Agency,
Research Triangle Park, NC, January 1978.
11. Review of NO^ Emission Factors for Stationary Fossil Fuel Combustion
Sources, EPA-450/4-79-021, U. S. Environmental Protection Agency,
Research Triangle Park, NC, September 1979.
12. Standards of Performance for New Stationary Sources, 36 FR 24876, December
23, 1971.
13. L. Scinto, Primary Sulfate Emissions from Coal and Oil Combustion, EPA
Contract Number 68-02-3138, TRW Inc., Redondo Beach, CA, February 1980.
14. S. T. Cuffe and R. W. Gerstele, Emissions from Coal Fired Power Plants;
A Comprehensive Summary, 999-AP-35, U. S. Environmental Protection Agency,
Research Triangle Park, NC, 1967.
1.1-14 EMISSION FACTORS 9/88
-------
15. Field Testing; Application of Combustion Modifications To Control
Emissions from Utility Boilers, EPA-650/2-74-066, U. S. Environmental"
Protection Agency, Washington, DC, June 1974.
16. Control of Utility Boiler and Gas Turbine Pollutant Emissions by Combus-
tion Modification - Phase I, EPA-600/7-78-036a, U. S. Environmental
Protection Agency, Washington, DC, March 1978.
17. Low-sulfur Western Coal Use in Existing Small and Intermediate Size
Boilers, EPA-600/7-78-153a, U. S. Environmental Protection Agency,
Washington, DC, July 1978.
18. Hazardous Emission Characterization of Utility Boilers, EPA-650/2-75-066,
U. S. Environmental Protection Agency, Washington, DC, July 1975.
19. Application of Combustion Modifications To Control Pollutant Emissions
from Industrial Boilers - Phase I, EPA-650/2-74-078a, U. S. Environmental
Protection Agency, Washington, DC, October 1974.
20. Field Study To Obtain Trace Element Mass Balances at a Coal Fired Utility
Boiler, EPA-600/7-80-171, U. S. Environmental Protection Agency, Washing-
ton, DC, October 1980.
21. Environmental Assessment of Coal and Oil Firing in a Controlled Industrial
Boiler, Volume II, EPA-600/7-78-164b, U. S. Environmental Protection
Agency, Washington, DC, August 1978.
22. Coal Fired Power Plant Trace Element Study, U. S. Environmental Protection
Agency, Denver, CO, September 1975.
23. Source Testing of Duke Power Company, Plezer, SC, EMB-71-CI-01, U. S.
Environmental Protection Agency, Research Triangle Park, NC, February 1971.
24. J. W. Kaakinen, et al., "Trace Element Behavior in Coal-fired Power Plants",
Environmental Science and Technology, 9(9):862-869, September 1975.
25. Five Field Performance Tests on Koppers Company Precipitators, Docket No.
OAQPS-78-1, Office Of Air Quality Planning And Standards, U. S. Environ-
mental Protection Agency, Research Triangle Park, NC, February-March 1974.
26. H. M. Rayne and L. P. Copian, Slag Tap Boiler Performance Associated with
_Power Plant Flyash Disposal, Western Electric Company, Hawthorne Works,
Chicago, IL, undated.
27. A. B. Walker, "Emission Characteristics for Industrial Boilers", Air
Engineering, 9(8):17-19, August 1967.
28. Environmental Assessment of Coal-fired Controlled Utility Boiler, EPA-600/
7-80-086, U. S. Environmental Protection Agency, Washington, DC, April
1980.
29. Steam, 37th Edition, Babcock and Wilcox, New York, 1963.
9/88 External Combustion Sources 1.1-15
-------
30. Industrial Boiler; Emission Test Report, Formica Corporation, Cincinnati,
Ohio, EMB-8Q-IBR-7, U. S. Environmental Protection Agency, Research Triangle
Park, NC, October 1980.
31. Field Tests of Industrial Stoker Coal-fired Boilers for Emissions Control
and Efficiency Improvement - Site A, EPA-600/7-78-135a, U. S.Environ-
mental Protection Agency, Washington, DC, July 1978.
32. ibidem-Site C, EPA-600/7-79-130a, May 1979.
33. ibidem-Site E, EPA-600/7-80-064a, March 1980.
34. ibidem-Site F, EPA-600/7-80-065a, March 1980.
35. ibidem-Site G, EPA-600/7-80-082a, April 1980.
36. ibidem-Site B. EPA-600/7-79-04la, February 1979.
37. Industrial Boilers; Emission Test Report, General Motors Corporation,
Parma, Ohio, Volume I, EMB-80-IBR-4, U. S. Environmental Protection Agency,
Research Triangle Park, NC, March 1980.
38. A Field Test Using Coal; dRDF Blends in Spreader Stoker-fired Boilers,
EPA-600/2-80-095, U. S. Environmental Protection Agency, Cincinnati, OH,
August 1980.
39. Industrial Boilers; Emission Test Report, Rickenbacker Air Force Base,
Columbus, Ohio, EMB-80-IBR-6, U. S. Environmental Protection Agency,
Research Triangle Park, NC, March 1980.
40. Thirty-day Field Tests of Industrial Boilers; Site 1, EPA-600/7-80-085a,
U. S. Environmental Protection Agency, Washington, DC, April 1980.
41. Field Tests of Industrial Stoker Coal-fired Boilers for Emissions Control
and Efficiency Improvement - Site D, EPA-600/7-79-237a, U. S. Environmental
Protection Agency, Washington, DC, November 1979.
42. ibidem-Site H. EPA-600/7-80-112a, May 1980.
43. ibidem-Site I, EPA-600/7-80-136a, May 1980.
44. Ibidem-Site J, EPA-600/7-80-137a, May 1980.
45. ibidem-Site K, EPA-600/7-80-138a, May 1980.
46. Regional Air Pollution Study; Point Source Emission Inventory, EPA-600/4-
77-014, U. S. Environmental Protection Agency, Research Triangle Park, NC,
March 1977.
47. R. P. Hangebrauck, et al., "Emissions of Polynuclear Hydrocarbons and
Other Pollutants from Heat Generation and Incineration Process", Journal
of the Air Pollution Control Association, 14(7):267-278, July 1964.
1.1-16 EMISSION FACTORS 9/88
-------
48. Source Assessment; Coal-fired Industrial Combustion Equipment Field Test,
EPA-600/,2-78-004o, U. S. Environmental Protection Agency, Washington, DC,
June 1978.
49. Source Sampling Residential Fireplaces for Emission Factor Development,
EPA-450/3-76-010, U. S. Environmental Protection Agency, Research Triangle
Park, NC, November 1975.
50. Atmospheric Emissions from Coal Combustion; An Inventory Guide, 999-AP-24,
U. S. Environmental Protection Agency, Washington, DC, April 1966.
51. Application of Combustion Modification To Control Pollutant Emissions from
Industrial Boilers - Phase II, EPA-600/2-76-086a, U. S. Environmental
Protection Agency, Washington, DC, April 1976.
52. Continuous Emission Monitoring for Industrial Boiler, General Motors Cor-
poration, St. Louis, Missouri, Volume I, EPA Contract Number 68-02-2687,
GCA Corporation, Bedford, MA, June 1980.
53. Survey of Flue Gas Desulfurization Systems; Cholla Station, Arizona
Public Service Company, EPA-600/7-78-048a, U. S. Environmental Protection
Agency, Washington, DC, March 1978. o
54. ibidem; La Cygne Station, Kansas City Power and Light, EPA-600/7-78-048d,
March 1978.
55. Source Assessment; Dry Bottom^Utility Boilers Firing Pulverized Bituminous
Coal, EPA-600/2-79-019, U. S. Environmental Protection Agency, Washington,
DC, August 1980.
56. Thirty-day Field Tests of Industrial Boilers; Site 3 - Pulverized - Coal
Fired Boiler, EPA-600/7-80-085c, U. S. Environmental Protection Agency,
Washington, DC, April 1980.
57. Systematic Field Study of Nitrogen Oxide Emission Control Methods for
Utility Boilers, APTD-1163, U. S. Environmental Protection Agency, Research
Triangle Park, NC, December 1971.
58. Emissions of Reactive Volatile Organic Compounds from Utility Boilers,
EPA-600/7-80-111, U. S. Environmental Protection Agency, Washington, DC,
May 1980.
59. Industrial Boilers; Emission Test Report, DuPont Corporation, Parkers-
burg, West Virginia, EMB-80-IBR-12, U. S. Environmental Protection Agency,
Research Triangle Park, NC, February 1982.
60. Technology Assessment Report for Industrial Boiler Applications^ NOV
Combustion Modification, EPA-600/7-79-178f, U. S. Environmental Protection
- Agency, Washington, DC, December 1979.
61. Inhalable Particulate Source Category Report for External Combustion
Sources, EPA Contract No. 68-02-3156, Acurex Corporation, Mountain View,
CA, January 1985.
9/88 External Combustion Sources 1.1-17
-------
1.2 ANTHRACITE COAL COMBUSTION
1.2.1 General1-2
Anthracite coal is a high rank coal with more fixed carbon and less vola-
tile matter than either bituminous, coal or lignite, and it has higher ignition
and ash fusion temperatures. Because of its low volatile matter content and
slight clinkering, anthracite is most commonly fired in medium sized traveling
grate stokers and small hand fired units. Some anthracite (occasionally with
petroleum coke) is used in pulverized coal fired boilers. It is also blended
with bituminous coal. None is fired in spreader stokers. For its low sulfur
content (typically less than 0.8 weight percent) and minimal smoking tendencies,
anthracite is considered a desirable fuel where readily available.
In the United States, all anthracite is mined in northeastern Pennsylvania
and is consumed mostly in Pennsylvania and several surrounding states. The
largest use of anthracite is for space heating. Lesser amounts are employed
for steam/.electric production; coke manufacturing, sintering and pelletizing;
and other industrial uses. Anthracite currently is only a small fraction of
the total quantity of coal combusted in the United States.
1.2.2 Emissions And Controls2"14
Particulate emissions from anthracite combustion are a function of furnace
firing configuration, firing practices (boiler load, quantity and location of
underfire air, sootblowing, flyash retnjection, etc.), and the ash content of
the coal. Pulverized coal fired boilers emit the highest quantity of partic-
ulate per unit of fuel because they fire the anthracite in suspension, which
results in a high percentage of ash carryover Into exhaust gases. Pulverized
anthracite fired boilers operate in the dry tap or dry bottom mode, because of
anthracite's characteristically high ash fusion temperature. Traveling grate
stokers and hand fired units produce much less partlculate per unit of fuel
fired, because combustion takes place in a quiescent fuel bed without signifi-
cant ash carryover into the exhaust gases. In general, particulate emissions
from traveling grate stokers will increase during sootblowing and flyash rein-
jection and with higher fuel bed underfeed air from forced draft fans. Smoking
is rarely a problem, because of anthracite's low volatile matter content.
Limited data are available on the emission of gaseous pollutants from
anthracite combustion. It is assumed from, bituminous coal combustion data that
a large fraction of the fuel sulfur is emitted as sulfur oxides. Also, because
combustion equipment, excess air rates, combustion temperatures, etc., are
similar between anthracite and bituminous coal combustion, nitrogen o-ide and
carbon monoxide emissions are assumed to be similar, too. Volatile organic
compound (VOC) emissions, however, are expected to be considerably lower,
since the volatile matter content of anthracite is significantly less than that
of bituminous coal.
9/88 External Combustion Sources 1.2-1
-------
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EMISSION FACTORS
9/88
-------
Controls on anthracite emissions mainly have been applied to particulate
matter. The most efficient particulate controls, fabric filters, scrubbers and
electrostatic precipltators", have been installed on large pulverized anthracite
fired boilers. Fabric filters and venturi scrubbers can effect collection
efficiencies exceeding 99 percent. Electrostatic precipitators typically are
only 90 to 97 percent efficient, because of the characteristic high resistivity
of low sulfur anthracite fly ash. It is reported that higher efficiencies can
be achieved using larger precipitators and flue gas conditioning. Mechanical
collectors are frequently employed upstream from these devices for large part-
icle removal.
Traveling grate stokers are often uncontrolled. Indeed, particulate
control has often been considered unnecessary, because of anthracite's low smok-
ing tendencies and of the fact that a significant fraction of large size flyash
from stokers is readily collected in flyash hoppers as well as in the breeching
and base of the stack. Cyclone collectors have been employed on traveling
grate stokers, and limited information suggests these devices may be up to 75
percent efficient on particulate. Flyash reinjection, frequently used in
traveling grate stokers to enhance fuel use efficiency, tends to increase
particulate emissions per unit of fuel combusted.
Emission factors for pollutants from anthracite coal combustion are given
in Table 1.2-1, and factor ratings in Table 1.2-2. Cumulative size distribution
data and size specific emission factors and ratings for particulate emissions
are in Tables 1.2-3 and 1.2-4. Uncontrolled and controlled size specific emis-
sion factors are presented in Figures 1.2-1 and 1.2-2. Size distribution data
for bituminous coal combustion may be used for uncontrolled emissions from
pulverized anthracite fired furnaces, and data for anthracite fired traveling
grate stokers may be used for hand fired units.
TABLE 1.2-2. ANTHRACITE COAL EMISSION FACTOR RATINGS
Furnace type
Pulverized coal
Traveling grate
stoker
Hand fired units
Particulate
B
B
B
Sulfur
oxides
B
B
B
Nitrogen
oxides
B
B
B
Carbon
monoxide
B
B
B
Volatile organics
Nonmethane
C
C
D
Methane
C
C
D
9/88
External Combustion Sources
1.2-3
-------
TABLE 1.2-3. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC
EMISSION FACTORS FOR DRY BOTTOM BOILERS BURNING PULVERIZED
ANTHRACITE COAL3
EMISSION FACTOR RATING: D
Particle el*eb
-------
TABLE 1.2-4. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC
EMISSION FACTORS FOR TRAVELING GRATE STOKERS BURNING ANTHRACITE COALa
EMISSION FACTOR RATING: E
Particle sizeb
(urn)
15
10
6
2.5
1.25
1.00
0.625
TOTAL
Cumulative mass Z
£ stated size
Uncontrolled0
64
52
42
27
24
23
d
100
Cumulative emission
[kg/Mg (Ib/ton) coal,
factor
as fired]
Uncontrolled
2.9 (5.8)
2.4 (4.8)
1.9 (3.8)
1.2 (2.4)
1.1 (2.2)
1.1 (2.2)
d
4.6 (9.2)
Reference 19.
^Expressed as aerodynamic equivalent diameter.
cMay also be used for uncontrolled hand fired units.
Insufficient data.
j—i—i i 1,1 n
i
.1 .2 .4 .6 1 2 46 10 20 40 60 100
Particle diameter (uni)
Figure 1.2-2,
Cumulative size specific emission factors for traveling
grate stokers burning anthracite coal.
9/88
External Combustion Sources
1.2-5
-------
References for Section 1.2
1. Minerals Yearbook, 1978-79, Bureau of Mines, U. S. Department of the
Interior, Washington, DC, 1981.
2. Air Pollutant Emission Factors, APTD-0923, U. S. Environmental Protection
Agency, Research Triangle Park, NC, April 1970.
3. Steam, 38th Edition, Babcock and Wilcox, New York, NY, 1975.
4. Fossil Fuel Fired Industrial Boilers - Background Information for Proposed
Standards, Draft, Office Of Air Quality Planning And Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 1980.
5. R. W. Cass and R. W. Bradway, Fractional Efficiency of a Utility Boiler
Baghouse; Sunbury Steam Electric Station, EPA-600/2-76-077a, U. S.
Environmental Protection Agency, Washington, DC, March 1976.
6. R. P. Janaso, "Baghouse Dust Collectors on a Low Sulfur Coal Fired Utility
Boiler", Presented at the 67th Annual Meeting of the Air Pollution Control
Association, Denver, CO, June 1974.
7. J. H. Phelan, et al., Design and Operation Experience with Baghouse Dust
Collectors for Pulverized Coal Fired Utility Boilers - Sunbury Station,
Holtwood Station, Proceedings of the American Power Conference, Denver,
CO, 1976.
8. Source Test Data on Anthracite Fired Traveling Grate Stokers, Office Of
Air Quality Planning And Standards, U. S. Environmental Protection Agency,
Research Triangle Park, NC, 1975.
9. Source and Emissions informationT on Anthracite Fired Traveling Grate
Stokers, Office Of Air Quality Planning And Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC, 1975.
10. R. J. Milligan, et al., Review of NCy Emission Factors for Stationary
Fossil Fuel Combustion Sources, EPA-450/4-79-021, U. S. Environmental
Protection Agency, Research Triangle Park, NC, September 1979.
11. N. F. Suprenant, et al., Emissions Assessment of Conventional Stationary
Combustion Systems, Volume IV; Commercial/Institutional Combustion
Sources, EPA Contract No. 68-02-2197, GCA Corporation, Bedford, MA, October
1980.
12. Source Sampling of Anthracite Coal Fired Boilers, RCA-Electronic Com-
ponents, Lancaster, Pennsylvania, Final Report, Scott Environmental
Technology, Inc., Plumsteadville, PA, April 1975.
13. Source Sampling of Anthracite Coal Fired Boilers, Shippensburg State
College, Shippensburg, Pennsylvania, Final Report, Scott Environmental
Technology, Inc., Plurasteadville, PA, May 1975.
1.2-6 EMISSION FACTORS 9/88
-------
14. W. Bartok, et al., Systematic Field Study of NCy Emission Control Methods
for Utility Boilers, APTD-1163, U. S. Environmental Protection Agency,
Research Triangle Park, NC, December 1971.
15. Source Sampling of Anthracite Coal Fired Boilers, Ashland State General
Hospital, Ashland, Pennsylvania, Final Report, Pennsylvania Department of
Environmental Resources, Harrisburg, PA, March 16, 1977.
16. Source Sampling of Anthracite Coal Fired Boilers, Norristown State Hospi-
tal, Norrlstown, Pennsylvania, Final Report, Pennsylvania Department of
Environmental Resources, Harrisburg, PA, January 19, 1980.
17. Source Sampling of Anthracite Coal Fired Boilers, Pennhurst Center, Spring
City, Pennsylvania, Final Report, TRC Environmental Consultants, Inc.,
Wethersfield, CT, January 23, 1980.
18. Source Sampling of Anthracite Coal Fired Boilers, West Chester State, West
Chester, Pennsylvania, Final Report, Roy Weston, Inc., West Chester, PA,
April 4, 1977.
19. Inhalable Part.iculate Source Category Report for External Combustion
Sources, EPA Contract No. 68-02-3156, Acurex Corporation, Mountain View,
CA, January 1985.
9/88 External Combustion Sources 1.2-7
-------
1.10 RESIDENTIAL WOOD STOVES
1.10.1 General1"2
Wood stoves are commonly used as space heaters to supplement conventional
heating systems in residences. They are increasingly found as the primary
source of heat, as well.
Because of differences in both the magnitude and the composition of
emissions from wood stoves, four different categories of stoves should be con-
sidered when estimating emissions:
- the conventional noncatalytic wood stove
- the noncatalytic low emitting wood stove
- the pellet fired noncatalytic wood stove
- the catalytic wood stove
Among these categories, there are many variations in wood stove design and
operation characteristics.
The conventional stove category comprises all stoves without catalytic
combustors and are not included in the other noncatalytic categories. Stoves '
of many different airflow designs, such as updraft, downdraft, crossdraft, and
S-flow, may be in this category.
"Noncatalytic low emitting" wood stoves are those having no catalyst and
meeting EPA certification standards.
Pellet fired stoves are fueled with pellets of sawdust, wood products,
and other biomass materials pressed into manageable shape and size. These
stoves have a specially designed or modified grate to accommodate this type
of fuel.
Catalytic stoves are equipped with a ceramic or metal honeycomb
material, called a combustor or converter, that is coated with a noble metal
such as platinum or palladium. The catalyst material reduces the ignition
temperature of the unburned hydrocarbons and carbon monoxide in the exhaust
gases, thus augmenting their ignition and combustion at normal stove operating
temperatures. As these components of the gases burn, the temperature inside
the catalyst increases to a point where the ignition of the gases is essen-
tially self sustaining.
1.10.2 Emissions3-13
The combustion and pyrolysis of wood in wood stoves produce atmospheric
emissions of particulate, carbon monoxide, nitrogen oxides, organic compounds,
mineral residues, and to a lesser extent, sulfur oxides. The quantities and
types of emissions are highly variable and depend on a number of factors,
including the stages of the combustion cycle. During inital stages of burning,
after a new wood charge is introduced, emissions increase dramatically,
primarily of volatile organic compounds (VOC). After the initial period of
External Combustion Sources 1.10-1
-------
high burn rate, there is a charcoal stage of the burn cycle, characterized by a
slower burn rate and decreased emission rates. Emission rates during this
stage are cyclical, characterized by relatively long periods of low emissions
with shorter episodes of emission spikes.
Particulate emissions are defined in this document as the total catch
measured by the EPA Method 5H (Oregon Method 7) sampling train. A small
portion of wood stove particulate emissions includes "solid" particles of
elemental carbon and wood. The vast majority of the particulate emissions
is condensed organic products of incomplete combustion equal to or less than
10 micrometers in aerodynamic diameter
Although reported particle size data are scarce, one reference states that
95 percent of the particles in the emissions from a wood stove were less than
0.4 micrometers in size.^
Sulfur oxides are formed by oxidation of sulfur in the wood. Nitrogen
oxides are formed by oxidation of fuel and atmospheric nitrogen. Mineral
constituents, such as potassium and sodium compounds, are also released from
the wood matrix during combustion. The high levels of organic compound and
carbon monoxide emissions result from incomplete combustion of the wood. "
Organic constituents of wood smoke vary considerably in both type and
volatility. These constituents include simple hydrocarbons (Cj-Cy), which exist
as gases or which volatilize at ambient conditions, and complex low volatility
substances which condense at ambient conditions. These low volatility conden-
sable materials are generally considered to have boiling points below 300°C
(572°F).
Polycyclic organic matter (POM) is an important component of the
condensable fraction of wood smoke. POM contains a wide range of compounds,
including organic compounds formed by the combination of free radical species
in the flame zone through incomplete combustion. This group contains some
potentially carcinogenic compounds, such as benzo(a)pyrene.
Emission factors and their ratings for wood combustion in residential
wood stoves are presented in Table 1.10-1.
As mentioned, particulate emissions are defined as the total emissions
collected by EPA Method 5H (Oregon Method 7). This method employs a heated
filter followed by three impingers, an unheated filter, and a final impinger.
Emissions data used to develop the factors in Table 1.10-1 are from a data
base developed during EPA certification tests and from data collected during
field testing programs. See Reference 1 for detailed discussions of EPA
Methods 5H and 28.
Note that the data shown on Table 1.10-1 have been derived primarily from
laboratory tests. Review of some emission tests of woodstoves in actual use
indicates that laboratory tests may underestimate actual emissions significantly,
Evaluation of field test results is proceeding, with completion scheduled for
October 1988.
1.10-2 EMISSION FACTORS
-------
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External Combustion Sources
1.10-3
-------
References for Section 1.10
1. G. E. Weant, Emission Factor Documentation For AP-42 Section 1.10,
Residential Wood Stoves, EPA Contract No. 68-02-3888, Engineering Science,
Inc., Gary, NC. In Printing.
2. R. Gay and J. Shah, Technical Support Document For Residential Wood
Combustion, EPA-450/4-85-012, U. S. Environmental Protection Agency,
Research Triangle Park, NC, February 1986.
3. Residential Wood Heater Test Report, Phase 1, Tennessee Valley Authority,
Chattanooga, TN, November 1982.
4. J. A. Rau and J. J. Huntzicker, "Composition And Size Distribution of
Residential Wood Smoke Aerosols", Presented at the 21st Annual Meeting of
the Air Pollution Control Association, Pacific Northwest International
Section, Portland, OR, November 1984.
5. R. C. McCrillis and R. G. Merrill, "Emission Control Effectiveness Of A
Woodstove Catalyst And Emission Measurement Methods Comparison", Presented
at the 78th Annual Meeting of the Air Pollution Control Association,
Detroit, MI, 1985.
6. L. E. Cottone and E. Messer, Test Method Evaluations and Emissions Testing
For Rating Wood Stoves, EPA-600/2-86-100, U. S. Environmental Protection
Agency, Research Triangle Park, NC, October 1986.
7. K. E. Leese and S. M. Hackins, Integrated Air Cancer Project - Source
Measurement, EPA Contract No, 68-02-3992, Research Triangle Institute,
Research Triangle Park, NC, March 1986.
8. Residential Wood Heater Test Report. Phase II. Vol. 1. Tennessee Valley
Authority, Chattanooga, TN, August 1983.
9. J. M. Allen, et al., Study Of The Effectiveness Of A Catalytic Combustion
Device On A Wood Burning Appliance, EPA-600/7-84-04, U. S. Environmental
Protection Agency, Research Triangle Park, NC, March 1984.
10. J. M. Allen and W. M. Cooke, Control Of Emissions From Residential Wood
Burning By Combustion Modification, EPA-600/7-81-091, U. S. Environmental
Protection Agency, Research Triangle Park, NC, May 1981.
11. R. S. Truesdale and J. G. Cleland, "Residential Stove Emissions From Coal
And Other Fuels Combustion", Presented at the Specialty Conference on
Residential Wood and Coal Combustion, Louisville, KY, March 1982.
12. R. E. Imhoff, et al., "Final Report On A Study Of The Ambient Impact Of
Residential Wood Combustion in Petersville, Alabama", Presented at the
Specialty Conference on Residential Wood and Coal Combustion, Louisville,
KY, March 1982.
1-10.-4 EMISSION FACTORS
-------
13. D, G, Deangelis, et al., Preliminary Characterization Of Emissions From
Wood-fired Residential Combustion Equipment. EPA-600/7-80-040, U. S.
Environmental Protection Agency, Cincinnati, OH, March 1980.
14. Standards Of Performance For New Stationary Sourcest New Residential Wood
Heaters. 53 FR 5860, February 26, 1988.
External Combustion Sources 1.10-5
-------
1.11 WASTE OIL COMBUSTION
1.11.1 General
"Waste oil" or "used oil" refers to spent lubricating and other in-
dustrial oils that are recovered for reuse as fuels, road oils and processed
oils. The principal type of waste oil is used vehicle crankcase oil recovered
by automobile service stations and waste oil collection depots. Other types of
waste oil include metal working lubricants, heavy hydrocarbon fuels, animal and
vegetable oils and fats, and industrial oils, including those used as trans-
former and other heat transfer fluids. Common contaminants in waste oils
include metals, halogens, various volatile organic compounds (VOC) and solvents,
and sulfur. Lead is found in appreciable quantities in used crankcase oil
because of the use of tetraalkyllead gasoline additives. Many other metals and
sulfur are introduced directly during formulation of lubricating oils as com-
ponents of additives. Also, metals can be introduced through abrasion and wear
of lubricated parts and surfaces. Halogens are introduced from the use of
organic halides as lead scavengers in gasoline, or through commingling of waste
oils and cleaning solvents such as perchloroethylene. Commingling of used oil
and other organic compounds during collection and storage appears to be a
common occurrence, as evidenced by the large number of relatively low molecular
weight organics frequently found in used oils but not present in the original
oils.1
In 1983, over 8.7 billion liters (2.3 billion gallons) of automotive and
industrial lubricating oils and other industrial oils were sold.1"^ Of this
total, 4.6 billion liters (1.2 billion gallons) were recovered as used oil and
subsequently reused or disposed of. The remainder was lost through engine
breakdown during engine operation, end use application, leakage and handling.
Waste oil combustion consumed 2.2 billion liters (0.59 billion gallons), or
roughly half of the recovered total, up appreciably from 1970 estimates
because of higher fuel costs, past fuel shortages, and the decline of other
outlets for used oil, such as road oilant or base stock for re-refining.3
Waste oil may be burned alone or mixed with other fuel oil, in most
conventional oil burning combustion systems. Several problems are associated
with waste oil combustion, including reduced combustion efficiency and the
corrosion and erosion of system components. However, these problems are not
felt to be serious., and they can be reduced if the waste oil is blended with
fuel oil or if the used oil is treated to reduce sediment, water, light end and
metal content. Metal emissions can be reduced if a vaporizing burner rather
than an atomizing burner is used in small waste oil space heaters.
1.11.2 Emissions
Emission factors for uncontrolled waste oil combustion are presented in
Table 1.11-1. Lead emissions depend on the oil's lead content and on boiler
and burner design and operating conditions. Because of greatly decreased use
of lead in gasoline, the lead content of waste oil has dropped significantly,
falling from 10,000 parts per million in 1970 to 1,100 parts per million in
1982-83 and to 300 - 500 parts per million in 1985.2~3 While further decreases
9/88
External Combustion Sources 1.11-1
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1.11-2
EMISSION FACTORS
9/88
-------
are forecast, the current lead content is still appreciably higher than the up
to 100 parts per million levels found in conventional fuels. Typically, 50
percent or more of the lead in waste oil is emitted with flue gas during
combustion, with the remainder deposited on internal surfaces. 3,5-10 However,
in small space heaters employing vaporizing burners, less than 5 percent of the
lead in the waste oil is emitted. 3
Cumulative size distribution data and size specific emission factors for
uncontrolled particulate emissions from waste oil combustion in commercial or
industrial boilers and air atomizing space heaters are presented in Tables
1.11-2 and 1.11-3. Uncontrolled size specific emission factors are presented
in Figures 1.11-1 and 1.11-2. Particulate emissions are based on the ash
content of the fuel. Because the ash content of waste oil is generally higher
than that found in refined oils, emissions from waste oil combustion will be
greater.
Emissions of other pollutants, such as sulfur dioxide (SOjj) and hydro-
chloric acid (HC1), will depend on the respective sulfur and chlorine levels in
the oil. Because levels of these precursor materials are generally greater in
waste oils than in refined fuel oils, particularly distillate oil, waste oil
combustion will produce more emissions of SOX and HC1. In contrast, emissions
of nitrogen oxides (NOX) , carbon monoxide (CO) and VOCs are similar for both
waste and refined fuels.
1.11.3 Controls
Pretreatment - Most waste oil now sold as a fuel receives some sort of physical
pretreatment (e. g. , sedimentation, filtration, centrif ugation, water and light
end distillation). Lead and other trace element concentrations and the ash
content of the waste oil generally will be lowered somewhat by some of these
pretreatments, probably less than 30 percent. While lead and ash content
reduction will reduce emissions of lead and particulate matter proportionately,
its purpose is to reduce water, sediment and low boiling components. This
provides a safely handled fuel with combustion properties similar to those of
conventional fuels and with physical properties resembling a No. 4 fuel.-*
Thus, criteria pollutant emissions primarily affected by overall combustion
efficiency (carbon monoxide and VOCs) will be similar to those from con-
ventional fuels. &
Other criteria pollutants, such as sulfur and NOX which depend either
totally or partially on the fuel sulfur and nitrogen contents, will be emitted
at levels consistent with those concentrations. Fuel sulfur and nitrogen
levels generally do not decline with pretreatment. Because waste oil sulfur
usually contains more sulfur than does distillate oil, emission factors for its
combustion will be proportionally higher. Similarly, the higher nitrogen
content of the waste oil can be expected to result in higher nitrogen oxide
emissions. Emissions of chloride will be directly related to the chlorine
content of the fuel, with 80 to 90 percent of the chlorine emitted as HC1.8~9
Many chlorinated organlcs, such as the low molecular weight chlorinated sol-
vents, will be removed during pretreatments employing light end distillation.
However, chlorine bearing compounds with vapor pressures similar to those of
the virgin base stock (e. g. , polychlorinated biphenyls) will not be removed by
this pretreatment. Expensive hydro finishing, or possibly clay contacting
operations, must be used to remove such chlorine.
9/88 External Combustion Sources 1.11-3
-------
TABLE 1.11-2.
CUMULATIVE SIZE DISTRIBUTION FOR UNCONTROLLED
PARTICULATE EMISSIONS AND SIZE SPECIFIC EMISSION FACTORS
FOR COMMERCIAL/INDUSTRIAL BOILERS FIRING WASTE
Particle sizeb
(urn)
15
10
6
2.5
1.25
1.00
0.625
Cumulative mass %
_< stated size
88
84
78
67
57
53
45
Emission factor0
(kg/m3) (lb/103 gal)
6.4(A) 54(A)
6.1(A) 51(A)
5.7(A) 48(A)
4.9(A) 41(A)
4.2(A) 35(A)
3.9(A) 32(A)
3.3(A) 27(A)
aReference 1. A • ash content in fuel.
^Expressed as aerodynamic equivalent diameter.
cBased on an overall particulate emission factor of 7.3(A) kg/m3
[61(A) lb/103 gal].
TABLE 1.11-3.
CUMULATIVE SIZE DISTRIBUTION FOR UNCONTROLLED
PARTICULATE EMISSIONS AND SIZE SPECIFIC EMISSION FACTORS
FOR AN AIR ATOMIZING SPACE HEATER UNIT FIRING WASTE OIL*
Particle sizeb
(urn)
15
10
6
2.5
1.25
1.00
0.625
Cumulative mass %
< stated size
91
89
»2
68
53
48
39
Emission factor0
(kg/m3) (lb/103 gal)
7.0(A)
6.8(A)
6.3(A)
5.2(A)
4.1(A)
3.7(A)
3.0(A)
58(A)
57(A)
52(A)
44(A)
34(A)
31(A)
25(A)
aReference 5. A = ash content in fuel.
^Expressed as aerodynamic equivalent diameter.
cBased on an overall particulate emission factor of 7.7(A) kg/m3
[64(A) lb/103 gal].
1.11-4
EMISSION FACTORS
9/88
-------
10A
OA
0.1
1 10
PARTICLE DIAMETER, micrometers
100
Figure l.ll-l. Cumulative size specific particulate emission
factors for commercial/industrial boilers
firing waste oil.
10A
6A
o| 4A
11
2 2A
OA
I I I I I 1 I I !
0.1
1 10
PARTICLE DIAMETER, micrometers
100
Figure 1.11-2. Cumulative size specific particulate emission
factors for an air atomizing space heater unit
firing waste oil.
9/88
External Combustion Sources
1.11-5
-------
Blending - Blending waste fuel and virgin fuel oil generally will reduce emis-
sions of lead, particulate, sulfur dioxide and hydrochloric acid. Emissions
of these pollutants will be approximately proportional to the respective con-
centrations of lead, ash, sulfur and chlorine in the blended fuel. NOX emis-
sions may also be reduced, although available data do not support a reduction
estimate. Emissions of VOC and carbon monoxide, which depend on combustion
efficiency, will not be significantly affected by blending.
Unit Design - There has been an increase in the use of waste oil as a fuel in
small space heaters (those with less than 250,000 British Thermal Units per
hour input).8,10 Two types of burners are employed in these combustion systems,
air atomizing and vaporizing. The conventional air atomizer injects aerosolized
oil vapor into the combustion chamber, whereas the vaporizing burner operates
through volatilization of heated oil. In the latter, the vapors are burned,
and a residue is left behind in the vaporizing pot. The atomizing units emit
at least an order of magnitude more particulate, lead and trace elements than
do the vaporizing units. Although levels of VOC and other unburned combustible
emissions appear comparable from both types of units, limited data suggest a
significantly higher level of polycyclic organic matter emitted from vaporizing
burners.
Control Equipment - Apart from the measure of control introduced by pretreat-
ment, blending or the use of vaporizing burners, no additional controls are
being applied to waste oil combustion. Waste oils are usually burned in small
devices, for which controls are virtually nonexistent. Because greater than
80 percent of the lead bearing particulate is submicron in diameter, only high
efficiency control devices such as fabric filters can provide significant
control. Mechanical collectors will achieve little if any measurable control,
either of lead emissions or of the submicron fraction of the particulate (about
55 percent) emitted in flue gas.8
References for Section 1.11
1. Composition And Management Of Used Oil Generated In The United States,
PB85-180297, National Technical Information Service, Springfield, VA,
November 1985.
2. Waste Oil; Technology, Economics, And Environmental Health And Safety
Considerations, U. S. Department Of Energy, Washington, DC, January 1987.
3. N. F. Surprenant, et al., The Fate Of Hazardous And Nonhazardous Wastes In
Used Oil Disposal And Recycling, DOE/BC/10375-6, U. S. Department Of
Energy, Bartlesville, OK, October 1983.
4. T. D. Coyle and A. R. Siedle, "Metals In Oil: Occurrence And Significance
For Reuse Of Spent Automotive Lubricating Oils", Measurements And Standards
For Recycled Oil - II, Special Publication 556, National Bureau Of
Standards, Gaithersburg, MD, September 1979.
5. Final Report Of The API Task Force On Oil Disposal, American Petroleum
Institute, New York, NY, May 1970.
1.11-6 EMISSION FACTORS 9/88
-------
6. G. A. Chappell, Waste Oil Reprocessing, Project No. 72-5, Esso Research
and Engineering Co., Government Research Laboratory, Linden, NJ, January
1973.
7. D. A. Waite, et al., "Waste Oil Combustion: An Environmental Case Study",
presented at the 75th Annual Meeting of the Air Pollution Control
Association, New Orleans, LA, June 1982.
8. Environmental Characterization Of Disposal Of Waste Oils In Small
Combustors, EPA-600/2-84-150, U. S. Environmental Protection Agency,
Cincinnati, OH, September 1984.
9. Used Oil Burned As A Fuel, EPA-SW-892, U. S. Environmental Protection
Agency, Washington, DC, August 1980.
10. R. E. Hall, et al., "Comparison Of Air Pollutant Emissions From Vaporizing
And Air Atomizing Waste Oil Heaters", Journal of the Air Pollution Control
Association. 33/7):683-687, July 1983.
11. R. L. Barbour and W. M. Cooke, Chemical Analysis Of Waste Crankcase Oil
Combustion Samples, EPA-600/7-83-026, U. S. Environmental Protection
Agency, Cincinnati, OH, April 1983.
12. W. B. Walker and R. Salter, Pollution Of The Environment By The Burning Of
Waste Oils. PB83-004943, National Technical Information Service,
Springfield, VA, September 1980.
9/88
External Combustion Sources 1.11-7
-------
2.1 REFUSE COMBUSTION
Refuse combustion generally means the burning of predominantly nonhazardous
garbage or other wastes. Types of combustion devices used to burn refuse
include single chamber units, multiple chamber units, trench incinerators, con-
trolled air incinerators, and pathological incinerators. These devices are
used to burn municipal, commercia'l, industrial, pathological, and domestic
refuse.
2.1.1 Municipal Waste Combustion*
Mass burn excess air combustion is the predominant method of burning
municipal solid waste (MSW). Approximately 70 percent of the MSW burned is
burned in mass burn units. The term "mass burn" means the burning of MSW with-
out any prior processing other than the removal of bulky items (stoves, tele-
phone poles, etc.) to produce a more homogeneous fuel. Mass burn units are
preferred for disposal of large amounts (up to 2700 megagrams metric tons [3000
tons] per day) of MSW. Some mass burn units coincinerate MSW and sewage sludge.
A second type of municipal waste combustor is the starved air or modular
combustor. Starved air combustors are the most common type of combustor because
they handle smaller amounts (up to 450 megagrams [500 tons] per day) of MSW.
Another type of municipal waste combustor is the refuse-derived fuel (RDF)
combustor. Refuse-derived fuel combustors burn MSW from which metals and other
noncombustible materials have been removed. Because of the processing costs
associated with producing RDF, these units are not as popular as mass burn or
starved units. Some RDF is incinerated with coal or sewage sludge.
2.1.2 Process Description^'^
Mass Burn Combustors - Typically, an overhead crane mixes MSW in a storage
pit and then moves it into a feed chute. A hydraulic ram system under the feed
chute charges the waste onto a grate system. As the waste is moved through the
combustion chamber by the grate system, it passes through three zones: a dryout
zone, where moisture in the waste is evaporated; a combustion zone; and a burn-
out zone, where final combustion occurs. The resulting ash falls into a flooded
ash pit and is removed and sent to a landfill. In some cases, ferrous metals
are removed from the ash by magnetic separation. The capacity of individual
combustors can range from 50 to 1000 megagrams of waste per day, and usually 2
or 3 units are at a site.
Several types of grate systems are used with mass burn combustors. They
are all similar in being designed to move the waste through the combustor and
to promote complete combustion. The grates can be traveling, rocking, recipro-
cating, roller, or rotary designs. The combustion process is supplied with
underfire air, which is introduced into multiple compartments, or plenums,
under the stoker grates, and with overfire air from nozzles or openings above
the grates.
New mass burn combustors can be expected to have a water wall furnace to
recover energy in the form of steam. Many older facilities have refractory
lined walls rather than water walls. Large mass burn units are usually field
erected.
9/88 Solid Waste Disposal 2.1-1
-------
The air pollution control systems for these combustors are electrostatic
precipitators (ESP), dry fabric filters (FF), dry scrubbing systems (with
either ESPs or FFs), and wet scrubbers.
Starved Air Combustors - A typical such unit has separate primary and
secondary chambers. The primary chamber is fed MSW by a hopper and ram feed
system. Air is supplied to the primary chamber at substoichiometric levels.
Rams in the primary chamber push residue and break up clinker. Exhaust gases,
including incomplete combustion products, (mostly carbon monoxide and hydro-
carbons of low molecular weight) pass into the secondary combustion chamber.
In the secondary combustion chamber, more air is added, and combustion is
completed. The resulting hot gases, 1000° to 1200°C (1800° to 2200°F), can be
passed through a heat recovery boiler for energy recovery, and all new starved
air combustors can be expected to have such systems. Ashes are quenched and
removed for disposal. Most existing starved air municipal waste combustors
operate without emission control systems, although some have ESPs or fabric
filters for particulate control. Starved air combustors generally are available
on the market and can be installed relatively quickly.
Refuse-derived Fuel Combustors - An alternative to direct combustion of MSW
is processing the waste to produce refuse-derived fuel (RDF). The four main
types of RDF are fluff, densified, powdered, and wet pulped. Fluff RDF is
prepared by mechanical shredding of MSW, followed by air classification,
magnetic separation, or trommeling to reduce the noncombustible content of the
waste stream. If multiple shredding stages are used, fine RDF is produced.
Densified RDF is fine RDF extruded in a pellet mill. Production of powdered
RDF requires mechanical, thermal and chemical processing of shredded MSW that
has undergone screening and magnetic separation. In the wet pulping process,
the pulper is fed wet MSW that has been sluiced with water. Noncombustibles
are removed in a liquid cyclone, then the RDF is then mechanically dewatered
to a moisture content of 50 percent.
Boilers dedicated to RDF combustion are of basically the same design as
those used for coal combustion. Typical configurations include suspension,
stoker, and fluidized bed designs. These boilers may burn up to 900 megagrams
(1000 tons) of RDF per day. The ash is quenched and removed to a landfill.
Most RDF units use ESPs for particulate matter control.
2.1.3 Emissions And Controls^"^
Refuse incinerators have the potential to emit significant quantities of
pollutants to the atmosphere. One of these pollutants is particulate matter,
emitted because of the turbulent movement of the combustion gases with respect
to the burning sludge and resultant ash. Particulate matter is also produced
when metals that are volatilized in the combustion zone condense in the exhaust
gas stream. Particle sizes and particulate concentrations leaving the inciner-
ator vary widely, depending on the composition of the refuse being burned and
on the type and operation of the incineration process.
Incomplete combustion of refuse, through improper incinerator design or
operating conditions, can result in emissions of intermediate products such as
volatile organic compounds and carbon monoxide. Other potential emissions
2.1-2 EMISSION FACTORS 9/88
-------
include sulfur dioxide, nitrogen oxides, metals, acid gases, and toxic organic
compounds.
A wide variety of control technologies is used to control refuse
incinerator emissions. Currently, the most widely used devices are ESPs,
fabric filters, wet scrubbers and dry scrubbers. Many control systems use a
combination of these.
Electrostatic precipitators are used on 75 percent of existing municipal
waste incinerators, to control particulate emissions. The efficiency of a
typical ESP can range from 90 to 99 percent, depending on particle size
distribution, gas flow rate and particle resistivity.
Fabric filters generally have not been applied directly to flue gases from
municipal incinerators, but rather are used as sorbent collectors and secondary
reactors for dry and semidry scrubbers. With upstream scrubbing of acid gases
and sorbent accumulation on fabric materials, fabric filters become a viable
choice for control of fine particulate as well as other pollutants.
Many types of wet scrubbers are used for removing acid gases - spray
towers, centrifugal scrubbers and venturi scrubbers. Scrubbers with internals,
such as packed beds and trays, are less commonly used. In wet scrubbers, the
exhaust gas enters the absorber and contacts enough alkaline solution to satur-
ate the gas stream. The alkaline solution reacts with the acid gases to form
salts, which are generally insoluble and removable by sequential clarifying,
thickening and vacuum filtering. The dewatered salts or sludges are then used
as landfill.
The two types of dry scrubbing are dry injection and semidry scrubbing.
In both, the material collected in the particle collector is dry. Dry injection
is the injection of a solid powder such as lime or sodium bicarbonate into the
flue gas (with a separate water injection). Acid gas removal occurs in the
duct and continues in the dust collector, as sorbent and ash particles and
condensed volatile matter are captured. In a semidry process, also known as
spray drying or wet/dry scrubbing, the sorbent enters the flue gas as a liquid
spray, with sufficient moisture to promote rapid absorption of acid gases, but,
because the moisture evaporates, only dry solid particles collector.
Emission factors for municipal waste incinerators are shown in Table 2.1-1.
Table 2.1-2 shows the cumulative particle size distribution and size specific
emission factors for municipal waste combustors. Figures 2.1-1, 2.1-2 and
2.1-3 show the cumulative particle size distribution and size specific emission
factors for mass burn, starved air and RDF combustors, respectively.
2.1.4 Other Types Of Combustion2>5-7
The most common types of combustors have a refractory lined chamber with
a grate upon which refuse is burned. In some newer incinerators, water walled
furnaces are used. Combustion products are formed by heating and burning refuse
on the grate. In most cases, since insufficient underfire air is provided to
complete combustion, additional air is admitted above the burning waste to
promote complete gas phase combustion. In multiple chamber incinerators, gases
from the primary chamber flow to a small secondary mixing chamber, where more
air is admitted and more extensive oxidation occurs. As much as 300 percent
9/88 Solid Waste Disposal 2.1-3
-------
12
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Figure 2.1-1. Cumulative particle size distribution and
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Figure 2.1-2. Cumulative particle size dlstrLbati.on and
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2.1-4
EMISSION FACTORS
9/88
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Cumulative particle size distribution and
size specific emission factors for refuse-
derived fuel combustors.
excess air may be supplied in order to promote oxidation of combustibles.
Auxiliary burners are sometimes installed in the mixing chamber to increase the
combustion temperature. Many small incinerators are single chamber units in
which gases vent from the primary combustion chamber directly into the exhaust
stack. Single chamber incinerators of this type do not meet modern air pollution
codes.
2.1.5 Process Description2»5-7
Industrial/Commercial Combustors - The capacities of these units cover a
wide range, generally between 23 and 1800 kilograms (50 and 4000 pounds) per
hour. Of either single or multiple-chamber design, these units are often
manually charged and intermittently operated. Some industrial combustors are
similar to municipal combustors in size and design. Better designed emission
control systems include gas fired afterburners, scrubbers, or both.
Trench Combustors - A trench combustor is designed to handle wastes of
relatively high heat content and low ash content. The design is a simple
U-shaped combustion chamber formed by the sides and bottom of the pit, and air
is supplied from nozzles (or fans) along the top of the pit. The nozzles are
directed at an angle below the horizontal, to provide a curtain of air across
9/88
Solid Waste Disposal
2.1-5
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EMISSION FACTORS
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2.1-8
EMISSION FACTORS
11/88
-------
the top of the pit and to provide air for combustion in the pit. Low con-
struction and operating costs have led to use of this combustor to dispose of
materials other than those for which it was originally designed. Emission
factors for trench combustors used to burn three such materials are given in
Table 2.I.3.8
Domestic Combustors - This category includes corabustors marketed for
residential use. Fairly simple in design, they may have single or multiple
chambers and usually are equipped with an auxiliary burner to aid combustion.
Flue Fed Combustors - These units, commonly found in large apartment
houses, are characterized by the charging method of dropping refuse down the
combustor flue and into the combustion chamber. Modified flue fed incinerators
utilize afterburners and draft controls to improve combustion efficiency and to
reduce emissions.
Pathological Combustors - These are combustors used to dispose of animal
remains and other organic material of high moisture content. Generally, these
units are able to process 23 to 45 kilograms (50 to 100 pounds) of such waste
per hour. Wastes are burned on a hearth in the combustion chamber. The units
are equipped with combustion controls and afterburners to ensure good combustion
and reduced emissions. <.
2.1.6 Emissions And Controls2»9
Operating conditions, composition of refuse, and basic combustor design
have a pronounced effect on emissions. The manner in which air is supplied to
the combustion chamber or chambers has a significant effect on the quantity of
particulate emissions. Air may- be introduced from beneath, aside or atop the
combustion chamber. As underfire air is increased, an increase in fly ash
emissions occurs. Erratic refuse charging causes a disruption of the com-
bustion bed and subsequent release of large quantities of particulate. Large
amounts of uncombusted particulate and carbon monoxide also are emitted for
an extended period after the charging of batch fed units, because of inter-
ruptions in the combustion process. In continuously fed units, furnace parti-
culate emissions strongly depend on grate type. Use of a rotary kiln and
reciprocating grates results in higher particulate emissions than does use of a
rocking or traveling grate. Emissions of oxides of sulfur depend on the sulfur
content of the refuse. Carbon monoxide and unburned hydrocarbon emissions may
be significant, and are caused by poor combustion resulting from improper
combustor design or operating conditions. Nitrogen oxide emissions increase
with increases in combustion zone temperature, residence time in the combustion
zone before quenching, and excess air rates to the point where dilution cooling
overcomes the effect of increased oxygen concentration.6
References for Section 2.1
\
1. Appendix A; Characterization of the Municipal Waste Combustion Industry,
Radian Corporation, Research Triangle Park, NC, October 1986,
2. Air Pollutant Emission Factors, APTD-0923, U. S. Environmental Protection
Agency, Research Triangle Park, NC, April 1970.
9/88 Solid Waste Disposal 2.1-9
-------
3. Emission Factor Documentation For AP-42 Section 2.1.1; Municipal Waste
Combustion (Draft), Office Of Air Quality Planning And Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, September
1987.
4. C. B. Sedman and T. G. Brna, Municipal Waste Combustion Study: Flue Gas
Cleaning Technology, EPA/530-SW-87-021d, U. S. Environmental Protection
Agency, Research Triangle Park, NC, June 1987.
5. Control Techniques for Carbon Monoxide Emissions from Stationary Sources,
AP-65, U. S. Environmental Protection Agency, Cincinnati, OH, March 1970.
6. Air Pollution Engineering Manual, AP-40, U. S. Environmental Protection
Agency, Cincinnati, OH, 1967. Out of Print.
7. J. DeMarco, et al., Incinerator Guidelines, 1969, 13TS, U. S. Environmental
Protection Agency, Cincinnati, OH, 1969.
8. J. 0. Brukle, J. A. Dorsey and B. T. Riley, "The Effects of Operating
Variables and Refuse Types on Emissions from a Pilot-scale Trench
Incinerator", Proceedings of the 1968 Incinerator Conference, American
Society of Mechanical Engineers, New York, NY, May 1968.
9. Walter R. Nessen, Systems Study of Air Pollution from Municipal
Incineration, Contract No. CPA-22-69-23, Arthur D. Little, Incorporated,
Cambridge, MA, March 1970.
10. C. V. Kanter, R. G. Lunche and A. P. Fururich, "Techniques for Testing Air
Contaminants from Combustion Sources", Journal Of The Air Pollution Control
Association, 6^(4): 191-199, February 1957.
11. J. L. Stear, Municipal Incineration: A Review of Literature, AP-79, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 1971.
12. E. R. Kaiser, Refuse Reduction Processes in Proceedings of Surgeon
General's Conference on Solid Waste Management, PHS No. 1729, U. S.
Public Health Service, Washington, DC, July 1967.
13. Unpublished source test data on incinerators, Resources Research,
Incorporated, Reston, VA, 1966-1969.
14. E. R. Kaiser, et al., "Modifications To Reduce Emissions From A Flue-fed
Incinerator", No. 552.2, College of Engineering, New York University, New
York, NY, June 1959.
15. Communication between Resources Research, Incorporated, Reston, VA, and
Division of Air Quality Control, Maryland State Department of Health,
Baltimore, MD, 1969.
16. Unpublished incinerator test data, Office of Air Quality Planning And
Standards, U. S. Environmental Protection Agency, Research Triangle Park,
NC, 1970.
2,1-10 EMISSION FACTORS 9/88
-------
I — 1*
2.1.2 Other Types of Combustors
The moat common types o£ combustors consist of a. refractory-lined
chamber with a grate upon which refuse is burned. In some newer
incinerators water-walled furnaces are used. Combust! . products are formed
by heating and burning of refuse on the grate. In most cases, since
insufficient underfire (undergrate) air is provided to enable complete
combustion, additional over-fire air is admitted above the burning waste to
promote complete gas-phase combustion. In multiple-chamber incinerators,
gases from the primary chamber flow to a small secondary-mixing chamber
where more air is admitted, and more complete oxidation occurs. As much as
300 percent excess air may be supplied in order to promote oxidation of
combustibles. Auxilliary burners are sometimes installed in the mixing
chamber to increase the combustion temperature. Many small-size incin-
erators are single-chamber units in which gases are vented from the primary
combustion chamber directly into the exhaust stack. Single-chamber
incinerators of this type do not meet modern air pollution codes.
i_i*
2.1.2.1 Process Description
Industrial/Commercial Combustors—The capacities of these units cover a
wide range, generally between 50 and 4,000 pounds (22.7 and 1,800 kilograms)
per hour. Of either single- or multiple-chamber design, these units are
often manually charged and intermittently operated. Some industrial
combustors are similar to municipal combustors in size and design. Better
designed emission control systems include gas-fired afterburners, scrubbers,
or both.
Trench Combustors—A trench combustor is designed for the combustion of
wastes having relatively high heat content and low ash content. The design
of the unit is simple: a U-shaped combustion chamber is formed by the sides
and bottom of the pit, and air is supplied from nozzles (or fans) along the
top of the pit. The nozzles are directed at an angle below the horizontal
to provide a curtain of air across the top of the pit and to provide air for
combustion in the pit. Low construction and operating costs have resulted
in the use of this combustor to dispose of materials other than those for
which it was originally designed. Emission factors for trench combustors
used to burn three such materials are included in Table 2.1.2-1.
Domestic Combustors—This category includes combustors marketed for
residential use. Fairly simple in design, they may have single or multiple
chambers and usually are equipped with an auxiliary burner to aid
combustion.
Flue-Fed Combustors—These units, commonly found in large apartment
houses, are characterized by the charging method of dropping refuse down the
combustor flue and into the combustion chamber. Modified flue-fed
incinerators utilize afterburners and draft controls to improve combustion
efficiency and reduce emissions.
Pathological Combustors—These are combustors used to dispose of animal
remains and other organic material of high moisture content. Generally,
these units are in a size range of 50 to 100 pounds (22.7 to 45.4 kilograms)
9/88 Solid Waste Disposal 2.1-11
-------
m u> IA
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per hour. Wastes are burned on a hearth in the combustion chamber. The
units are equipped with combustion controls and afterburners to ensure good
combustion and minimal emissions.
1.1.2.2 Emissions and Controls
Operating conditions, refuse composition, and basic combustor design
have a pronounced effect on emissions. The manner in which air is supplied
to the combustion chamber or chambers has a significant effect on the
quantity of particulate emissions. Air may be introduced from beneath the
chamber, from the side, or from the top of the combustion chamber. As
underfire air is increased, an increase in fly-ash emissions occurs.
Erratic refuse charging causes a disruption of the combustion bed and a
subsequent release of large quantities of particulates. Large quantities of
uncombusted particulate matter and carbon monoxide are also emitted for an
extended period after charging of batch-fed units because of interruptions
in the combustion process. In continuously fed units, furnace particulate
emissions are strongly dependent upon grate type. The use of a rotary kiln
and reciprocating grates results in higher particulate emissions than the
use of a rocking or traveling grate. Emissions of oxides of sulfur are
dependent on the sulfur content of the refuse. Carbon monoxide and unburned
hydrocarbon emissions may be significant and are caused by poor combustion
resulting from improper combustor design or operating conditions. Nitrogen
oxide emissions increase with an increase in the temperature of the
combustion zone, an increase in the residence time in the combustion zone
before quenching, and an increase in the excess air rates to the point where
dilution cooling overcomes the effect of increased oxygen concentration.
9/88 Solid Waste Disposal 2.1-13
-------
References for Section 2.1.2
1. Air Pollutant Emission Factors, Final Report, Resources Research,
Incorporated, Reston, VA, prepared for National Air Pollution Control
Administration, Durham, NC, under Contract Number CPA-2269-119,
April 1970.
2. Control Techniques for Carbon Monoxide Emissions from Stationary
Sources, U.S. DHEW, PHS, EHS, National Air Pollution Control
Administration, Washington, DC, Publication Number AP-65, March 1970.
3. Air Pollution Engineering Manual, U.S. DHEW, PHS, National Center for
Air Pollution Control, Cincinnati, OH, Publication Number 999-AP-40,
1967, p. 413-503.
4. J. DeMarco. et al., Incinerator Guidelines 1969, U.S. DHEW, Public
Health Service, Cincinnati, OH, SW. 13TS, 1969, p. 176.
5. J. 0. Brukle, J. A. Dorsey, and B. T. Riley, The Effects of Operating
Variables and Refuse Types on Emissions from a Pilot-Scale Trench
Incinerator, Proceedings of the 1968 Incinerator Conference, American
Society of Mechanical Engineers, New York, NY, May 1968, p. 34-41.
6. Walter R. Nessen, Systems Study of Air Pollution from Municipal
Incineration, Arthur D. Little, Inc. Cambridge, MA, prepared for
National Air Pollution Control Administration, Durham, NC, under
Contract Number CPA-22-69-23, March 1970.
7. C. V. Ranter, R. G. Lunche, and A. P. Fururich, Techniques for Testing
Air Contaminants from Combustion Sources, J. Air Pol. Control Assoc.,
6(4): 191-199, February 1957.
8. J. L. Stear, Municipal Incineration; A Review of Literature, U. S.
Environmental Protection Agency, Office of Air Programs, Research
Triangle Park, NC, OAP Publication Number AP-79, June 1971.
9. E. R. Kaiser, Refuse Reduction Processes in Proceedings of Surgeon
General's Conference on Solid Waste Management, Public Health Service,
Washington, DC, PHS Report Number 1729, July 10-20, 1967.
10. Unpublished source test data on incinerators, Resources Research,
Incorporated, Reston, VA, 1966-1969.
11. E. R. Kaiser, et al., Modifications to Reduce Emissions from a Flue-Fed
Incinerator, New York University, College of Engineering, Report
Number 552.2, June 1959, p. 40 and 49.
12. Communication between Resources Research, Incorporated, Reston, VA, and
Maryland State Department of Health, Division of Air Quality Control,
Baltimore, MD, 1969.
2.1-14 EMISSION FACTORS 9/88
-------
13. Unpublished data on incinerator testing. U.S. DHEW, PHS, EHS, National
Air Pollution Control Administration, Durham, NC, 1970.
9/88 Solid Waste Disposal 2.1-15
-------
2.5 SEWAGE SLUDGE INCINERATION
2.5.1 Process Description
In sewage sludge incineration, materials generated by wastewater
treatment plants are oxidized to reduce the volume of solid waste.
In the first step in the process, the sludge is dewatered until it is
15 to 30 percent solids so that it will burn without auxiliary fuel.
Dewatered sludge is conveyed to a combustion device where thermal oxidation
occurs. The unburned residual ash is removed from the combustion device,
usually on a continuous basis, and disposed. The exhaust gas stream is
directed to an air pollution control device, typically a wet scrubber.
Approximately 95 percent of sludge incinerators are multiple-hearth and
fluidized-bed designs. Multiple-hearth incinerators are vertically oriented
cylindrical shells containing from 4 to 14 refractory hearths stacked one
above the other. Sludge typically enters at the periphery of the top hearth
and is raked inward by the teeth on a rotating rabble arm to a drop hole
leading to the second hearth. The teeth on the rabble arm above the second
hearth are positioned in the opposite direction to move the sludge
outward. This outside-in, inside-out pattern is repeated on alternate
hearths. Fluidized-bed incinerators also are vertically oriented
cylindrical shells. A bed of sand approximately 0.7-meters (2.5-feet) thick
rests on the grid and is fluidized by air injected through the tuyeres
located at the base of the furnace within a refractory-lined grid. Sludge
is introduced directly into the bed. Temperatures in a multiple-hearth
furnace are 320°C (600°F) in the lower, ash-cooling hearth; 760° to 1100°C
(1400° to 2000°F) in the central combustion hearths; and 540° to 650°C
(1000° to 1200°F) in the upper, drying hearths. Temperatures in a
fluidized-bed reactor are fairly uniform, from 680° to 820°C (1250° to
1500°F). In both types of furnaces, an auxiliary fuel may be required
either during startup or when the moisture content of the sludge is too high
to support combustion.
Electric (infrared) furnaces are the newest of the technologies
currently in use for sludge incineration. The sludge is conveyed into one
end of the horizontally oriented incinerator where it is first dried and
then burned as it travels beneath the infrared heating elements.
Other sludge incineration technologies that are no longer in widespread
use include cyclonic reactors, rotary kilns, and wet oxidation reactors.
Some sludge is coincinerated with refuse.
j 2 if
2.5.2 Emissions and Controls ' '
Sludge incinerators have the potential to emit significant quantities
of pollutants to the atmosphere. One of these pollutants is particulate
matter, which is emitted because of the turbulent movement of the combustion
gases with respect to the burning sludge and resultant ash. The particle
size distribution and concentration of the particulate emissions leaving the
incinerator vary widely, depending on the composition of the sludge being
burned and the type and operation of the incineration process.
9/88 Solid Waste Disposal 2.5-1
-------
Total particulate emissions are usually highest for a fluidized-bed
incinerator because the combustion gas velocities required to fluidize the
bed result in entrainment of large quantities of ash in the flue gas.
Particulate emissions from multiple-hearth incinerators are usually less
than those from fluidized-bed incinerators because the agitation of ash and
gas velocity through the bed are lower in the multiple-hearth
incinerators. Electric furnaces have the lowest particulate matter
emissions because the sludge is not stirred or mixed during incineration and
air flows through the unit generally are quite low, resulting in minimal
entrainment.
Incomplete combustion of sludge can result in emissions of intermediate
products (e.g., volatile organic compounds and carbon monoxide). Other
potential emissions include sulfur dioxide, nitrogen oxides, metals, acid
gases, and toxic organic compounds.
Wet scrubbers are commonly used to control particulate and gaseous
(e.g., S02, NOx, CO, and VOC's) emissions from sludge incinerators. There
are two practical reasons for this: (1) a. wastewater treatment plant is a
source of relatively inexpensive scrubber water (plant effluent) and (2) a
system for the treatment of the scrubber effluent is available (spent
scrubber water is sent to the head of the treatment plant for solids removal
and pH adjustment). The most widely used scrubber types are venturi and
impingement-tray. Cyclone wet scrubbers and systems combining all three
types of scrubbers are also used.
•
Pressure drops for venturi, impingement tray, and cyclone scrubbers are
1 to 40 kPa, .0.4 kPa per stage, and 1 to 2 kPa, respectively. Collection
efficiency can range from 60 to 99 percent depending on the scrubber
pressure drop, particle size distribution, and particulate concentration.
Emission factors and emission factor ratings for sludge incinerators
are shown in Table 2.5-1. Table 2.5-2 shows the cumulative particle size
distribution and size specific emission factors for sewage sludge
incinerators. Figures 2.5-1, 2.5-2, and 2.5-3 show the cumulative particle
size distribution and size-specific emission factors for multiple-hearth,
fluidized-bed, and electric infrared incinerators, respectively.
2.5-2 EMISSION FACTORS
9/88
-------
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9/88
Solid Waste Disposal
2.5-3
-------
TABLE 2.5-2. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND SIZE SPECIFIC
EMISSION FACTORS FOR SEWAGE SLUDGE INCINERATORS3
Particle
size.
microns
15
10
5.0
2.5
1.0
0.625
TOTAL
"Reference
Cumulative mass % £ stated size
Uncontrolled Controlled
MHD Fbc Eta MH° Pbc Ela
15 NA 43 30 7.7 60
10 NA 30 27 7.3 50
5.3 NA 17 25 6.7 35
2.8 NA 10 22 6.0 25
1.2 NA 6.0 20 5.0 18
0.75 NA 5.0 17 2.7 15
100 100 100 100 100 100
5.
Cumu 1 at i ve
Uncontrol
MH° Fbc
6.0 NA
(12)
4.1 NA
(8.2)
2.1 NA
(4.2)
1.1 NA
(2.2)
0.47 NA
(0.94)
0.30 NA
(0.60)
40 NA
(80)
emission
led
El°
4.3
(8.6)
3.0
(6.0)
1.7
(3.4)
1.0
(2.0)
0.60
(1.2)
0.50
(1.0)
10
(20)
factor, kg/Mg (tb/ton)
Control led
MH° Fbc
0.12 0.23
(0.24) (0.46)
0.11 0.22
(0.22) (0.44)
0.10 0.20
(0.20) (0.40)
0.09 0.18
(0.18) (0.36)
0.08 0.15
(0.16) (0.30)
0.07 0.08
(0.14) (0.16)
0.40 3.0
(0.80) (6.0)
Ela
1.2
(2.4)
1.0
(2.0)
0.70
(1.4)
0.50
(1.0)
0.35
(0.70)
0.30
(0.60)
2.0
(4.0)
DMH * mul-tiple hearth.
CFB • fluidized bed.
°EI » electric infrared.
NA * not aval (able.
sT
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** 7 ^
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ti . f f\
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0.09 -H
CO
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g
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100
Figure 2.5-1. Cumulative particle aize distribution
size-specific emission factors for
multiple-hearth incinerators.
and
2.5-4
EMISSION FACTORS
9/88
-------
17010
Ptrtlclt d1«Mt«r
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0.20
00
s
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0.12 S
CO
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too
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figure 2.5*2. Cumulative particle size distribution and
size-specific emission factors for
fluidized-bed incinerators.
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REFERENCES FOR SECTION 2.5
1. Environmental Regulations and Technology; Use and Disposal of Municipal
Wastewater Sludge, EPA-625/10-84-003, U. S. Environmental Protection
Agency, Cincinnati, OH, September 1984.
2. Seminar Publication: Municipal Wastewater Sludge Combustion Technology,
EPA-625/4-85/015, U. S. Environmental Protection Agency, Cincinnati,
OH, September 198S.
3. Written communication from C. Hester, Midwest Research Institute, Cary,
NC, to J. Crowder, Office of Air Quality Planning and Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, September
1985.
4. Control Techniques for Particulate Emissions From Stationary Sources
Volume 1, EPA-45/3-81-005a, U. S. Environmental Protection Agency,
Research Triangle Park, NC, September 1982.
5. Draft report. Emission Factor Documentation for AP-42 Section 2.5—
Sewage Sludge Incineration, Monitoring and Data Analysis Division,
Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC, September 1987.
2.5-6 EMISSION FACTORS 9/88
-------
1 -»8
4.2.2.7 Polymeric Coating of Supporting Substrates
"Polymeric coating of supporting substrates" is defined as a web coating
process other than paper coating that applies an elastomer or other polymeric
material onto a supporting substrate. Typical substrates include woven, knit,
and nonwoven textiles; fiberglass; leather; yarn; and cord. Examples of
polymeric coatings are natural and synthetic rubber, urethane, polyvinyl
chloride, acrylic, epoxy, silicone, phenolic resins, and nitrocellulose.
Plants have from 1 to more than 10 coating lines. Most plants are commission
coaters where coated substrates are produced according to customer
specifications. Typical products include rainwear, conveyor belts, V-belts,
diaphragms, gaskets, printing blankets, luggage, and aircraft and military
products. This industrial source category has been retitled from "Fabric
Coating" to that listed above to reflect the general use of polymeric coatings
on substrate materials including but not limited to conventional textile
fabric substrates.
Process description ~ - The process of applying a polymeric coating to a
supporting substrate consists of mixing the coating ingredients (including
solvents), conditioning the substrate, applying the coating to the substrate,
drying/curing the coating in a drying oven, and subsequent curing or
vulcanizing if necessary. Figure 4.2.2.7-1 is a schematic of a typical
solvent-borne polymeric coating operation identifying volatile organic
compound (VOC) emission locations. Typical plants have one or two small
(<38 m or 10,000 gallons) horizontal or vertical solvent storage tanks which
are operated at atmospheric pressure, however, some plants have as many as
five. Coating preparation equipment includes the mills, mixers, holding
tanks, and pumps used to prepare polymeric coatings for application. Urethane
coatings typically are purchased premixed and require little or no mixing at
the coating plant. The conventional types of equipment for applying organic
solvent-borne and waterborne coatings include knife-over-roll, dip, and
reverse-roll coaters. Once applied to the substrate, liquid coatings are
solidified by evaporation of the solvent in a steam-heated or direct-fired
oven. Drying ovens usually are of forced-air convection design in order to
maximize drying efficiency and prevent a dangerous localized buildup of vapor
concentration or. temperature. For safe operation, the concentration of
organic vapors is usually held between 10 and 25 percent of the lower
explosive limit (LEL). Newer ovens may be designed for concentrations of up
to 50 percent of the LEL through the addition of monitors, alarms, and fail-
safe shutdown systems. Some coatings require subsequent curing or vulcanizing
in separate ovens.
Emissions sources ~ - The significant VOC emission sources in a
polymeric coating plant include the coating preparation equipment, the coating
application and flashoff area, and the drying ovens. Emissions from the
solvent storage tanks and the cleanup area are normally only a small
percentage of the total.
In the mixing or coating preparation area, VOC's are emitted from the
individual mixers and holding tanks during the following operations: filling
of mixers, transfer of the coating, intermittent activities such as changing
9/88 Evaporation Loss Sources 4.2.2.7-1
-------
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4.2.2.7-2
EMISSION FACTORS
9/88
-------
the filters in the holding tanks, and mixing (if mix equipment is not equipped
with tightly fitting covers). The factors affecting emissions in the mixing
area include tank size, number of tanks, solvent vapor pressure, throughput,
and the design and performance of tank covers.
Emissions from the coating application area result from the evaporation
of solvent around the coating application equipment during the application
process and from the exposed substrate as it travels from the coater to the
drying oven entrance (flashoff). The factors affecting emissions are the
solvent content of the coating, line width and speed, coating thickness,
volatility of the solvent(s), temperature, distance between coater and oven,
and air turbulence in the coating area.
Emissions from the drying oven result from the fraction of the remaining
solvent that is driven off in the oven. The factors affecting uncontrolled
emissions are the solvent content of the coating and the amount of solvent
retained in the finished product. Fugitive emissions due to the opening of
oven doors also may be significant in some operations. Some plasticizers and
reaction by-products may be emitted if the coating is subsequently- cured or
vulcanized. However, emissions from the curing or vulcanizing of the coating
are usually negligible compared to the total emissions from the operation.
Solvent type and quantity are the common factors affecting emissions from
all the operations in a polymeric coating facility. The rate of evaporation
or drying is dependent upon solvent vapor pressure at a given temperature and
concentration. The most commonly used organic solvents are toluene, dimethyl
formamide (DMF), acetone, methyl ethyl ketone (MEK), isopropyl alcohol,
xylene, and ethyl acetate. Factors affecting solvent selection are cost,
solvency, toxicity, availability, desired rate of evaporation, ease of use
after solvent recovery, and compatibility with solvent recovery equipment.
1 2 i* —7
Emissions control » ' - A control system for evaporative emissions
consists of two components: a capture device and a control device. The
efficiency of the control system is determined by the efficiencies of the two
components.
A capture device is used to contain emissions from a process operation
and direct them to a stack or to a control device. Covers, vents, hoods, and
partial and total enclosures are alternative capture devices used on coating
preparation equipment. Hoods and partial and total enclosures are typical
capture devices for use in the coating application area. A drying oven can be
considered a capture device because it both contains and directs VOC emissions
from the process. The efficiency of capture devices is variable and depends
upon the quality of design and the level of operation and maintenance.
A control device is any equipment that has as its primary function the
reduction of emissions. Control devices typically used in this industry are
carbon adsorbers, condensers, and incinerators. Tightly fitting covers on
coating preparation equipment may be considered both capture and control
devices.
Carbon adsorption units use activated carbon to adsorb VOC's from a gas
stream; the VOC's are later recovered from the carbon. Two types of carbon
9/88 Evaporation Loss Sources 4.2.2.7-3
-------
adsorbers are available: fixed bed and fluidized bed. Fixed-bed carbon
adsorbers are designed with a steam-stripping technique to recover the VOC
material and regenerate the activated carbon. The fluidized-bed units used in
this industry are designed to use nitrogen for VOC vapor recovery and carbon
regeneration. Both types achieve typical VOC control efficiencies of
95 percent when properly designed, operated, and maintained.
Condensation units control VOC emissions by cooling the solvent laden gas
to the dew point of the solvent(s) and collecting the droplets. There are two
condenser designs commercially available: nitrogen (inert gas) atmosphere and
air atmosphere. These systems differ in the design and operation of the
drying oven (i.e., use of nitrogen or air in the oven) and in the method of
cooling the solvent laden air (i.e., liquified nitrogen or refrigeration).
Both design types can achieve VOC control efficiencies of 95 percent.
Incinerators control VOC emissions through oxidation of the organic
compounds into carbon dioxide and water. Incinerators used to control VOC
emissions may be of thermal or catalytic design and may use primary or
secondary heat recovery to reduce fuel costs. Thermal incinerators operate at
approximately 890°C (1600°F) to assure oxidation of the organic compounds.
Catalytic incinerators operate in the range of 315° to 4308C (600° to 800°F)
while using a catalyst to achieve comparable oxidation of VOC's. Both design
types achieve a typical VOC control efficiency of 98 percent.
Tightly fitting covers control VOC emissions from mix vessels by reducing
evaporative losses. Airtight covers can be fitted with conservation vents to
avoid excessive internal pressure or vacuum. The parameters affecting the
efficiency of these controls are solvent vapor pressure, cyclic temperature
change, tank size, throughput, and the pressure and vacuum settings on the
conservation vents. A good system of tightly fitting covers on mixing area
vessels is estimated to reduce emissions by approximately 40 percent. Control
efficiencies of 95 or 98 percent can be obtained by directing the captured
VOC's to an adsorber, condenser, or incinerator.
When the efficiencies of the capture device and control device are known,
the efficiency of the control system can be computed by the following
equation:
(capture efficiency)x(control efficiency)=(control system efficiency).
The terms of this equation are fractional efficiencies rather than
percentages. For instance, a system of hoods delivering 60 percent of VOC
emissions to a 90 percent efficient carbon adsorber would result in a control
system efficiency of 54 percent (0.60x0.90=0.54). Table 4.2.2.7-1 summarizes
the control system efficiencies that may be used in the absence of measured
data on mix equipment and coating operations.
4.2.2.7-4 EMISSION FACTORS 9/88
-------
TABLE 4.2.2.7-1. SUMMARY OF CONTROL EFFICIENCIES*
OveraLl control
Control technology efficiency, %
Coating Preparation Equipment
Uncontrolled 0
Sealed covers with conservation vents 40
Sealed covers with carbon adsorber/condenser _ 95
Coating Operation0
Local ventilation with carbon adsorber/condenser 81
Partial enclosure with carbon adsorber/condenser 90
Total enclosure with carbon adsorber/condenser 93
Total enclosure with incinerator 96
^Reference 1. To be used in the absence of measured data.
To be applied to uncontrolled emissions from indicated process area, not
from entire plant.
clncludes coating application/flashoff area and drying oven.
1 !+ — 8
Emissions estimation techniques ' - In this diverse industry,
realistic estimates of emissions require solvent usage data. Due to the wide
variation found in coating formulations, line speeds, and products, no
meaningful inferences can be made based simply on the equipment present.
Plant-wide emissions can be estimated by performing a liquid material
balance in uncontrolled plants and in those where VOC's are recovered for
reuse or sale. This technique is based on the assumption that all solvent
purchased replaces VOC's which have been emitted. Any identifiable and
quantifiable side streams should be subtracted from this total. The general
formula for this is:
r solvent \r quantifiable \r VOC •>
'•purchased' '•solvent output' ^emitted'*
The first term encompasses all solvent purchased including thinners, cleaning
agents, and the solvent content of any premixed coatings as well as any
solvent directly used in coating formulation. From this total, any
quantifiable solvent outputs are subtracted. These outputs may include
solvent retained in the finished product, reclaimed solvent sold for use
outside the plant, and solvent contained in waste streams. Reclaimed solvent
which is reused at the plant is not subtracted.
9/88 Evaporation Loss Sources 4.2.2.7-5
-------
The advantages of this method are that it is based on data that are
usually readily available, it reflects actual operations rather than
theoretical steady state production and control conditions, and it includes
emissions from all sources at the plant. However, care should be taken not to
apply this method over too short a time span. Solvent purchases, production,
and waste removal occur in their own cycles, which may not coincide exactly.
Occasionally, a liquid material balance may be possible on a smaller
scale than the entire plant. Such an approach may be feasible for a single
coating line or group of lines served by a dedicated mixing area and a
dedicated control and recovery system. In this case, the computation begins
with total solvent metered to the mixing area instead of solvent purchased.
Reclaimed solvent is subtracted from this volume whether or not it is reused
onsite. Of course, other solvent input and output streams must be accounted
for as previously indicated. The difference between total solvent input and
total solvent output is then taken to be the quantity of VOC's emitted from
the equipment in question.
The configuration of meters, mixing areas, production equipment, and
controls usually will not make this approach possible. In cases where control
devices destroy potential emissions or a- liquid material balance is
inappropriate for other reasons, plant-wide emissions can be estimated by
summing the emissions balculated for specific areas of the plant. Techniques
for these calculations are presented below.
Estimating VOC emissions from a coating operation (application/f lashof f
area and drying oven) starts with the assumption that the uncontrolled
emission level is equal to the quantity of solvent contained in the coating
applied. In other words, all the VOC in the coating evaporates by the end of
the drying process. This quantity should be adjusted downward to account for
solvent retained in the finished product in cases where it is quantifiable and
significant.
Two factors are necessary to calculate the quantity of solvent applied:
the solvent content of the coating and the quantity of coating applied.
Coating solvent content can be directly measured using EPA Reference
Method 24. Alternative ways of estimating the VOC content include the use of
either data on coating formulation that are usually available from the plant
owner/operator or premixed coating manufacturer or, if these cannot be
obtained, approximations based on the information in Table 4.2.2.7-2. The
amount of coating applied may be directly metered. If it is not, it must be
determined from production data. These should be available from the plant
owner/operator. Care should be taken in developing these two factors to
assure that they are in compatible units.
When an estimate of uncontrolled emissions is obtained, the controlled
emissions level is computed by applying a control system efficiency factor:
uncontrolled]x(l.control
4.2.2.7-6 EMISSION FACTORS 9/88
-------
TABLE 4.2.2.7-2. SOLVENT AND SOLIDS CONTENT OF POLYMERIC COATINGS*
Typical percentage, by weight
Polymer type X solvent % solids
Rubber
Urethanes
Acrylics
Vinylc
Vinyl Plastisol
Organisol
Epoxies
Silicone
Nitrocellulose
50-70
50-60
b
60-80
5
15-40
30-40
50-60
70
30-50
40-50
50
20-40
95
60-85
60-70
40-50
30
Reference 1.
Organic solvents are generally not used in the formulation of acrylic
coatings. Therefore, the solvent content for acrylic coatings represents
nonorganic solvent use (i.e., water).
cSolvent-borne vinyl coating.
As previously explained, the control system efficiency is the product of the
efficiencies of the capture device and the control device. If these values
are not known, typical efficiencies for some combinations of capture and
control devices are presented in Table 4.2.2.7-1. It is important to note
that these control system efficiencies are applicable only to emissions that
occur within the areas served by the systems. Emissions from such sources as
process wastewater or discarded waste coatings may not be controlled at all.
In cases where emission estimates from the mixing area alone are desired,
a slightly different approach is necessary. Here, uncontrolled emissions will
be only that portion of total solvent that evaporates during the mixing
process. A liquid material balance across the mixing area (i.e., solvent
entering minus solvent content of coating applied) would provide a good
estimate. In the absence of any measured value, it may be assumed that
approximately 10 percent of the total solvent entering the mixing area is
emitted during the mixing process, but this can vary widely. When an estimate
of uncontrolled mixing area emissions has been made, the controlled emission
rate can be calculated as discussed previously. Table 4.2.2.7-1 lists typical
overall control efficiencies for coating mix preparation equipment.
Solvent storage tanks of the size typically found in this industry are
regulated by only a few States and localities. Tank emissions are generally
9/88 Evaporation Loss Sources 4.2.2.7-7
-------
small (<125 kg/yr). If an estimate of emissions is desired, it can be
computed using the equations, tables, and figures provided in Section 4.3.2.
REFERENCES FOR SECTION A.2.2.7
1. Polymeric Coating of Supporting Substrates—Background Information for
Proposed Standards, EPA-45Q/3-85-022a, U. S. Environmental Protection
Agency, Research Triangle Park., NC, October 1985.
2. Control of Volatile Organic Emissions From Existing Stationary Sources—
Volume II: Surface Coating of Cans, Coils, Paper, Fabrics, Automobiles,
and Light Duty Trucks, EPA-450/2-77-008, U. S. Environmental Protection
Agency, Research Triangle Park, NC, May 1977.
3. E. J. Maurer, "Coating Operation Equipment Design and Operating
Parameters," Memorandum to Polymeric Coating of Supporting Substrates
File, MRI, Raleigh, NC, April 23, 1984.
4. Control of Volatile Organic Emissions From Existing Stationary Sources—
Volume I; Control Methods for Surface-Coating Operations, EPA-450/2-76-
028, U. S. Environmental Protection Agency, Research Triangle Park, NC,
November 1976.
5. G. Crane, Carbon Adsorption for VOC Control, U. S. Environmental
Protection Agency, Research Triangle Park, NC, January 1982.
6. D. Moscone, "Thermal Incinerator Performance for NSPS," Memorandum, Office
of Air Quality Planning and Standards, U. S. Environmental Protection
Agency, Research Triangle Park, NC, June 11, 1980.
7. D. Moscone, "Thermal Incinerator Performance for NSPS, Addendum,"
Memorandum, Office of Air Quality Planning and Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, July 22,
1980.
8. C. Beall, "Distribution of Emissions Between Coating Mix Preparation Area
and the Coating Line," Memorandum to Magnetic Tape Coating Project File,
MRI, Raleigh, NC, June 22, 1984.
4.2.2.7-8 ... EMISSION FACTORS 9/88
-------
4.12 POLYESTER RESIN PLASTICS PRODUCT FABRICATION
4.12.1 General Description1"2
A growing number of products are fabricated from liquid polyester resin
reinforced with glass fibers and extended with various inorganic filler
materials such as calcium carbonate, talc, mica or small glass spheres.
These composite materials are often referred to as fiberglass reinforced
plastic (FRP), or simply "fiberglass". The Society Of The Plastics Industry
designates these materials as "reinforced plastics/composites" (RP/C). Also,
advanced reinforced plastics products are now formulated with fibers other
than glass, such as carbon, aramid and aramid/carbon hybrids. In some
processes, resin products are fabricated without fibers. One major product
using resins with fillers but no reinforcing fibers is5the synthetic marble
used in manufacturing bathroom countertops, sinks and related items. Other
applications of nonreinforced resin plastics include automobile body filler,
bowling balls and coatings.
Fiber reinforced plastics products have a wide range of application in
industry, transportation, home and recreation. Industrial uses include stor-
age tanks, skylights, electrical equipment, ducting, pipes, machine compo-
nents, and corrosion resistant structural and process equipment. In
transportation, automobile and aircraft applications are increasing rapidly.
Home and recreational items include bathroom tubs and showers, boats (build-
ing and repair), surfboards and skis, helmets, swimming pools and hot tubs,
and a variety of sporting goods.
The thermosetting polyester resins considered here are complex polymers
resulting from the cross-linking reaction of a liquid unsaturated polyester
with a vinyl type monomer, most often styrene. The unsaturated polyester is
formed from the condensation reaction of an unsaturated dibasic acid or
anhydride, a saturated dibasic acid or anhydride, and a polyfunctional
alcohol. Table 4.12-1 lists the most common compounds used for each compo-
nent of the polyester "backbone", as well as the principal cross-linking
monomers. The chemical reactions that form both the unsaturated polyester
and the cross-linked polyester resin are shown in Figure 4.12-1. The emis-
sion factors presented here apply to fabrication processes that use the
finished liquid resins (as received by fabricators from chemical manufac-
turers), and not to the chemical processes used to produce these resins.
(See Chapter 5, Chemical Process Industry.)
In order to be used in the fabrication of products, the liquid resin
must be mixed with a catalyst to initiate polymerization into a solid thermo-
set. Catalyst concentrations generally range from 1 to 2 percent by original
weight of resin; within certain limits, the higher the catalyst concentration,
the faster the cross-linking reaction proceeds. Common catalysts are organic
peroxides, typically methyl ethyl ketone peroxide or benzoyl peroxide.
Resins may contain inhibitors, to avoid self curing during resin storage,
and promoters, to allow polymerization to occur at lower temperatures.
9/88 Evaporation Loss Sources 4.12-1
-------
TABLE 4.12-1. TYPICAL COMPONENTS OF RESINS
To Form the Unsaturated Polyester
Unsaturated Acids Saturated Acids Polyfunctional Alcohols
Maleic anhydride Phthalic anhydride Propylene glycol
Fumaric acid Isophthalic acid Ethylene glycol
Adipic acid Diethylene glycol
Dipropylene glycol
Neopentyl glycol
Pentaerythritol
Cross-linking Agents (Monomers)
Styrene
Methyl methacrylate
Vinyl toluene
Vinyl acetate
Diallyl phthalate
Acrylamide
2-ethyl hexylacrylate
The polyester resin/fiberglass industry consists of many small faci-
lities (such as boat repair and small contract firms) and relatively few
large firms that consume the major fraction of the total resin. Resin
usage at these operations ranges from less than 5,000 kilograms per year
to over 3 million kilograms per year.
Reinforced plastics products are fabricated using any of several
processes, depending on their size, shape and other desired physical
characteristics. The principal processes include hand layup, spray layup
(sprayup), continuous lamination, pultrusion, filament winding and various
closed molding operations.
Hand layup, using primarily manual techniques combined with open
molds, is the simplest of the fabrication processes. Here, the reinforce-
ment is manually fitted to a mold wetted with catalyzed resin mix, after
which it is saturated with more resin. The reinforcement is in the form
of either a chopped strand mat, a woven fabric or often both. Layers of
reinforcement and resin are added to build the desired laminate thickness.
Squeegees, brushes and rollers are used to smooth and compact each layer
as it is applied. A release agent is usually first applied to the mold
to facilitate removal of the composite. This is often a wax, which can
be treated with a water soluble barrier coat such as polyvinyl alcohol to
promote paint adhesion on parts that are to be painted. In many operations,
4.12-2 EMISSION FACTORS 9/88
-------
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4.12-3
-------
the mold is first sprayed with gel coat, a clear or pigmented resin mix
that forms the smooth outer surface of many products. Gel coat spray
systems consist of separate sources of resin and catalyst, with an airless
hand spray gun that mixes them together into an atomized resin/catalyst
stream. Typical products are boat hulls and decks, swimming pools, bathtubs
and showers, electrical consoles and automobile components.
Spray layup, or "sprayup", is another open mold process, differing from
hand layup in that it uses mechanical spraying and chopping equipment for
depositing the resin and glass reinforcement. This process allows a greater
production rate and more uniform parts than does hand layup, and often uses
more complex molds. As in hand layup, gel coat is frequently applied to the
mold before fabrication to produce the desired surface qualities. It is
common practice to combine hand layup and sprayup operations.
For the reinforced layers, a device is attached to the sprayer system to
chop glass fiber "roving" (uncut fiber) into predetermined lengths and pro-
ject it to merge with the resin mix stream. The stream precoats the chop,
and both are deposited simultaneously to the desired layer thickness on the
mold surface (or on the gel coat that was applied to the mold). Layers are
built up and rolled out on the mold as necessary to form the part. Products
manufactured by sprayup are similar to those made by hand layup, except that
more uniform and complex parts can generally be produced more efficiently with
sprayup techniques. However, compared to hand layup, more resin generally is
used to produce similar parts by spray layup because of the inevitable over-
spray of resin during application.
Continuous lamination of reinforced plastics materials involves impreg-
nating various reinforcements with resins on an in-line conveyor. The
resulting laminate is cured and trimmed as it passes through the various con-
veyor zones. In this process, the resin mix is metered onto a bottom carrier
film, using a blade to control thickness. This film, which defines the pa-
nel's surface, is generally polyester, cellophane or nylon, and may have a
smooth, embossed or matte surface. Methyl methacrylate is sometimes used as
the cross-linking agent, either alone or in combination with styrene, to
increase strength and weather resistance. Chopped glass fibers free-fall
into the resin mix and are allowed to saturate with resin, or "wet out". A
second carrier film is applied on top of the panel before subsequent forming
and curing. The cured panel is then stripped of its films, trimmed and cut
to the desired length. Principal products include translucent industrial sky-
lights and greenhouse panels, wall and ceiling liners for food areas, garage
doors and cooling tower louvers. Figure 4.12-2 shows the basic elements of
a continuous laminating production line.
Pultrusion, which can be thought of as extrusion by pulling, is used to
produce continuous cross-sectional lineals similar to those made by extrud-
ing metals such as aluminum. Reinforcing fibers are pulled through a liquid
resin mix bath and into a long machined steel die, where heat initiates an
exothermic reaction to polymerize the thermosetting resin matrix. The compo-
site profile emerges from the die as a hot, constant cross-sectional that
cools sufficiently to be fed into a clamping and pulling mechanism. The pro-
duct can then be cut to desired lengths. Example products include electrical
insulation materials, ladders, walkway gratings, structural supports, and
rods and antennas.
4.12-4 EMISSION FACTORS 9/88
-------
Resin metering device—
x1^ ®ass cutler
/ . \£ Picker roll
Top Mm
Cure area
Healed welout table
Bottom dim
Fllm
rewind
9 Ed9e"
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rb-0'l 0
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^s lO-O-O-
Inspection area ! I
Slacking device
Figure 4.12-2. Typical continuous lamination production process.
Filament winding is the process of laying a band of resin impregnated
fibers onto a rotating mandrel surface in a precise geometric pattern, and
curing them to form the product. This is an efficient method of producing
cylindrical parts with optimum strength characteristics suited to the
specific design and application. Glass fiber is most often used for the
filament, but aramid, graphite, and sometimes boron and various metal wires
may be used. The filament can be wetted during fabrication, or previously
impregnated filament ("prepreg") can be used. Figure 4.12-3 shows the
filament winding process, and indicates the three most common winding
patterns. The process illustration depicts circumferential winding, while
the two smaller pictures show helical and polar winding. The various wind-
ing patterns can be used alone or in combination to achieve the desired
strength and shape characteristics. Mandrels are made of a wide variety of
materials and, in some applications, remain inside the finished product as
a liner or core. Example products are storage tanks, fuselages, wind
turbine and helicopter blades, and tubing and pipe.
catalysed resin
roving
traversing
Helical Winding
Polar Winding
Figure 4.12-3. Typical filament winding process.
9/88
Evaporation Loss Sources
4.12-5
-------
Closed, such as compression or injection, molding operations involve
the use of two matched dies to define the entire outer surface of the part.
When closed and filled with a resin mix, the matched die mold is subjected
to heat and pressure to cure the plastic. For the most durable production
configuration, hardened metal dies are used (matched metal molding).
Another closed molding process is vacuum or pressure bag molding. In bag
molding, a hand layup or sprayup is covered with a plastic film, and vacuum
or pressure is applied to rigidly define the part and improve surface
quality. The range of closed molded parts includes tool and appliance
housings, cookware, brackets and other small parts, and automobile body and
electrical components.
Synthetic marble casting, a large segment of the resin products indus-
try, involves production of bathroom sinks, vanity tops, bathtubs and
accessories using filled resins that have the look of natural marble. No
reinforcing fibers are used in these products. Pigmented or clear gel coat
can either be applied to the mold itself or sprayed onto the product after
casting to simulate the look of natural polished marble. Marble casting
can be an open mold process, or it may be considered a semiclosed process
if cast parts are removed from a closed mold for subsequent gel coat spray-
ing.
4.12.2 Emissions And Controls
Organic vapors consisting of volatile organic compounds (VOC) are emit-
ted from fresh resin surfaces during the fabrication process and from the
use of solvents (usually acetone) for cleanup of hands, tools, molds and
spraying equipment. Cleaning solvent emissions can account for over 36
percent of the total plant VOC emissions.^ There also may be some release
of particulate emissions from automatic fiber chopping equipment, but these
emissions have not been quantified.
Organic vapor emissions from polyester resin/fiberglass fabrication
processes occur when the cross-linking agent (monomer) contained in the
"liquid resin evaporates into the air during resin application and curing.
Styrene, methyl methacrylate and vinyl toluene are three of the principal
monomers used as cross-linking agents. Styrene is by far the most common.
Other chemical components of resins are emitted only at trace levels,
because they not only have low vapor pressures but also are substantially
converted to polymers. ->~6
Since emissions result from evaporation of monomer from the uncured
resin, they depend upon the amount of resin surface exposed to the air and
the time of exposure. Thus, the potential for emissions varies with the
manner in which the resin is mixed, applied, handled and cured. These fac-
tors vary among the different fabrication processes. For example, the
spray layup process has the highest potential for VOC emissions because the
atomization of resin into a spray creates an extremely large surface area
from which volatile monomer can evaporate. By contrast, the emission
potential in synthetic marble casting and closed molding operations is
considerably lower, because of the lower monomer content in the casting
resins (30 to 38 percent, versus about 43 percent) and of the enclosed
nature of these molding operations. It has been found that styrene
4.12-6 EMISSION FACTORS 9/88
-------
evaporation increases with increasing gel time, wind speed and ambient
temperature, and that increasing the hand rolling time on a hand layup or
sprayup results in significantly higher styrene losses.* Thus, production
changes that lessen the exposure of fresh resin surfaces to the air should
be effective in reducing these evaporation losses.
In addition to production changes, resin formulation can be varied to
affect the VOC emission potential, In general, a resin with lower monomer
content should produce lower emissions. Evaluation tests with low-styrene-
euisslon laminating resins having a 36 percent styrene content found a 60
to 70 percent decrease in emission levels, compared to conventional resins
(42 percent styrene), with no sacrifice in the physical properties of the
laminate.' Vapor suppressing agents also are sometimes added to resins to
reduce VOC emissions. Most vapor suppressants are paraffin waxes, stearates
or polymers of proprietary composition, constituting up to several weight
percent of the mix. Limited laboratory and field data indicate that vapor
suppressing resins reduce styrene losses by 30 to 70 percent.'~°
Emission factors for several fabrication processes using styrene con-
tent resins have been developed from the results of facility source tests (B
Rating) and laboratory tests (C Rating), and through technology transfer
estimations (D Rating).* Industry experts also provided additional infor-
mation that was used to arrive at the final factors presented in Table
4,12-2.6 Since the styrene content varies over a range of approximately 30
to 50 weight percent, these factors are based on the quantity of styrene
monomer used in the process, rather than on the total amount of resin used.
The factors for vapor-suppressed resins are typically 30 to 70 percent of
those for regular resins. The factors are expressed as ranges, because of
the observed variability in source and laboratory test results and of the
apparent sensitivity of emissions to process parameters.
Emissions should be calculated using actual resin monomer contents.
Uhen specific information about the percentage of styrene is unavailable,
the representative average values in Table 4.12-3 should be used. The sam-
ple calculation illustrates the application of the emission factors.
Sample Calculation - A fiberglass boat building facility
consumes an average of 250 kg per day of styrene-containing
resins using a combination of hand layup (75%) and spray layup
(25%) techniques. The laminating resins for hand and spray lay-
up contain 41.0 and 42.5 weight percent, respectively, of styrene.
The resin used for hand layup contains a vapor-suppressing agent.
From Table 4.12-2, the factor for hand layup using a vapor-suppresed
resin is 2 - 7 (0.02 to 0.07 fraction of total styrene emitted);
the factor for spray layup is 9 - 13 (0.09 to 0.13 fraction emit-
ted). Assume the midpoints of these emission factor ranges.
Total VOC emissions are:
(250 kg/day) [(0.41)(0.045)(0.75) + (0.425)(0.11)(0.25)J
= 6.4 kg/day.
9/88 Evaporation Loss Sources 4.12-7
-------
TABLE 4.12-2. EMISSION FACTORS FOR UNCONTROLLED POLYESTER RESIN
PRODUCT FABRICATION PROCESSES3
(100 x mass of VOC emitted/mass of monomer input)
Process
Hand layup
Spray layup
Continuous lamination
Pultrusiond
Filament winding6
Marble casting
Closed moldingg
Resin
NVS
5-10
9-13
4-7
4-7
5-10
1 - 3
1 - 3 "
VSb
2-7
3-9
1 - 5
1 - 5
2-7
1 - 2
1 - 2
Emission
Factor
Rating
C
B
B
D
D
B
D
Gel Coat
NVS
26 - 35
26 - 35
c
c
c
f
c
VSb
8-25
•
8-25
c
c
c
f
c
Emission
Factor
Rating
D
B
—
—
—
—
—
aReference 9. Ranges represent the variability of processes and sensiti-
vity of emissions to process parameters. Single value factors should be
selected with caution. NVS = nonvapor-suppressed resin. VS = vapor-sup-
pressed resin.
^Factors are 30-70% of those for nonvapor-suppressed resins.
cGel coat is not normally used in this process.
dResin factors for the continuous lamination process are assumed to apply.
eResin factors for the hand layup process are assumed to apply.
^Factors unavailable. However, when cast parts are subsequently sprayed
with gel coat, hand and spray layup gel coat factors are assumed to apply.
gResin factors for marble casting, a semiclosed process, are assumed to
apply.
TABLE 4.12-3. TYPICAL RESIN STYRENE PERCENTAGES
Resin Application
Resin Styrene Content3
(wgt. %)
Hand layup
Spray layup
Continuous lamination
Filament winding
Marble casting
Closed molding
Gel coat
43
43
40
40
32
35
35
aMay vary by at least ^5 percentage points.
4.12-8 EMISSION FACTORS
9/88
-------
Emissions from use of gel coat would be calculated in the same manner.
If the monomer content of the resins were unknown, a representative value
of 43 percent could be selected from Table 4.12-3 for this process combina-
tion. It should be noted that these emissions represent evaporation of
styrene monomer only, and not of acetone or other solvents used for clean-
up.
In addition to process changes and materials substitution, add-on con-
trol equipment can be used to reduce vapor emissions from styrene resins.
However, control equipment is infrequently used at RP/C fabrication facili-
ties, due to low exhaust VOC concentrations and the potential for contami-
nation of adsorbent materials. Most plants use forced ventilation techni-
ques to reduce worker exposure to styrene vapors, but vent the vapors
directly to the atmosphere with no attempt at collection. At one contin-
uous lamination facility where incineration was applied to vapors vented
from the impregnation table, a 98.6 percent control efficiency was mea-
sured. 1 Carbon adsorption, absorption and condensation also have been
considered for recovering styrene and other organic vapors, but these tech-
niques have not been applied to any significant extent in this industry.
Emissions from cleanup solvents can be controlled through good house-
keeping and use practices, reclamation of spent solvent, and substitution
with water based solvent substitutes.
References for Section 4.12
1. M. B. Rogozen, Control Techniques for Organic Gas Emissions from Fiber-
glass Impregnation and Fabrication Processes, ARB/R-82/165, California
Air Resources Board, Sacramento, CA, (NTIS PB82-251109), June 1982.
2. Modern Plastics Encyclopedia, 1986-1987, £3_ (10A), October 1986.
3. C. A. Brighton, G. Pritchard and G. A. Skinner, Styrene Polymers:
Technology and Environmental Aspects, Applied Science Publishers, Ltd.,
London, 1979.
4. M. Elsherif, Staff Report, Proposed Rule 1162 - Polyester Resin
Operations, South Coast Air Quality Management District, Rule Develop-
ment Division, El Monte, CA, January 23, 1987.
5. M. S. Crandall, Extent of Exposure to Styrene in the Reinforced Plastic
Boat Making Industry, Publication No. 82-110, National Institute For
Occupational Safety And Health, Cincinnati, OH, March 1982.
6. Written communication from R. C. Lepple, Aristech Chemical Corporation,
Polyester Unit, Linden, NJ, to A. A. MacQueen, U.S. Environmental Pro-
tection Agency, Research Triangle Park, NC, September 16, 1987.
7. L. Walewski and S. Stockton, "Low-Styrene-Emission Laminating Resins
Prove It in the Workplace", Modern Plastics, 62(8):78-80, August 1985.
9/88 Evaporation Loss Sources 4.12-9
-------
8. M. J. Duffy, "Styrene Emissions - How Effective Are Suppressed
Polyester Resins?", Ashland Chemical Company, Dublin, OH, presented
at 34th Annual Technical Conference, Reinforced Plastics/Composites
Institute, The Society Of The Plastics Industry, 1979.
9. G. A. LaFlam, Emission Factor Documentation for AP-42 Section 4.12;
Polyester Resin Plastics Product Fabrication, Pacific Environmental
Services, Inc., Durham, NC, November 1987.
4.12-10 EMISSION FACTORS 9/88
-------
5.15 SOAP AND DETERGENTS
5.15.1 Soap Manufacture
Process Description^ - Soap may be manufactured by either batch or continuous
process, using either the alkaline saponification of natural fats and oils or
the direct saponification of fatty acids. The kettle, or full boiled, method
is a batch process of several steps, in either a single kettle or a series of
kettles. Fats and oils are saponified by live steam boiling in a caustic
solution, followed by "graining", which is precipitating the soft curds of soap
out of the aqueous lye solution by adding sodium chloride (salt). The soap so-
lution then is washed to remove glycerine and color body impurities, to leave
the "neat" soap to form during a settling period. Continuous alkaline saponi-
fication of natural fats and oils follows the same steps as batch processing,
but it eliminates the need for a lengthy process time. Direct saponification
of fatty acids is also accomplished in continuous processes. Fatty acids
obtained by continuous hydrolysis usually are continuously neutralized with
caustic soda in a high speed mixer/neutralizer to form soap.
All soap is finished for consumer use in such varied forms as liquid,
powder, granule, chip, flake or bar.
Emissions And Controls^ - The main atmospheric pollution problem in the manu-
facture of soap is odor. Vent lines, vacuum exhausts, product and raw material
storage, and waste streams are all potential odor sources. Control of these
odors may be achieved by scrubbing^all exhaust fumes and, if necessary, inciner-
ating the remaining compounds. Odors emanating from the spray dryer may be
controlled by scrubbing with an acid solution.
Blending, mixing, drying, packaging and other physical operations all may
involve dust emissions. The production of soap powder by spray drying is the
largest single source of dust in the manufacture of soap. Dust emissions from
other finishing operations can be controlled by dry filters such as baghouses.
The large sizes of the particulate from soap drying mean that high efficiency
cyclones installed in series can give satisfactory control.
5.15.2 Detergent Manufacture
Process Description*"^ - The manufacture of spray dried detergent has three
main processing steps, slurry preparation, spray drying and granule handling.
Figure 5.15-1 illustrates the various operations. Detergent slurry is produced
by blending liquid surfactant with powdered and liquid materials (builders and
other additives) in a closed mixing tank called a crutcher. Liquid surfactant
used in making the detergent slurry is produced by the sulfonation, or sulfa-
tion by sulfuric acid, of either a linear alkylate or a fatty acid, which is
then neutralized with caustic solution (NaOH). The blended slurry is held in a
surge vessel for continuous pumping to a spray dryer. The slurry is sprayed at
high pressure into a vertical drying tower having a stream of hot air of from
315° to 400°C (600° to 750°F). Most towers designed for detergent production
are countercurrent, with slurry introduced at the top and heated air introduced
at the bottom. The detergent granules thus formed are conveyed mechanically
or by air from the tower to a mixer, to incorporate additional dry or liquid
ingredients, and finally to packaging and storage.
9/88 Chemical Process Industry 5.15-1
-------
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EMISSION FACTORS
9/88
-------
Emissions And Controls^ 3 - In the batching and mixing of fine dry ingredients
to form slurry, dust emissions are generated at scale hoppers, mixers and
crutchers. Fabric filters are used, not only to reduce or to eliminate the
dust emissions but also to recover raw materials. Emission factors for parti-
culate from spray drying operations are shown in Table 5.15-1. Table 5.15-2
and Figure 5.15-2 give size specific particulate emission factors for operations
on which information is available. There is also a minor source of volatile
organics when the product being sprayed contains organic materials with low
vapor pressures. These vaporized organic materials condense in the tower
exhaust air stream into droplets or particles.
Dry cyclones and cyclonic impingement scrubbers are the primary collection
equipment employed to capture the detergent dust in the spray dryer exhaust for
return to process. Dry cyclones are used, in parallel or in series, to collect
particulate (detergent dust) and to recycle it back to the crutcher. Cyclonic
impinged scrubbers are used, in parallel, to collect the particulate from a
scrubbing slurry and to recycle it to the crutcher. Secondary collection equip-
ment is used to collect the fine particulate that has escaped from the primary
devices. Cyclonic impingement scrubbers are often followed by mist eliminators,
and dry cyclones are followed by fabric filters or scrubber/electrostatic
precipitator units. Conveying, mixing and packaging of detergent granules can
cause dust emissions. Usually, fabric filters provide the best control.
TABLE 5.15-1. PARTICULATE EMISSION FACTORS FOR DETERGENT SPRAY DRYINGS
EMISSION FACTOR RATING: B
Particulate
Control
device
Uncontrolled
Cycloneb
Cyclone
w/Spray chamber
w/Packed scrubber
w/Venturi scrubber
w/Wet scrubber
w/Wet scrubber/ESP
Fabric filter
Efficiency
(%)
-
85
92
95
97
99
99.9
99
kg/Mg of
product
45
7
3.5
2.5
1.5
0.544
0.023
0.54
Ib/ton of
product
90
14
7
1.08
0.046
'.1
aReferences 4-8. VOC emissions data have not been reported in the
literature. Dash = not applicable. ESP = electrostatic precipitator.
bSome type of primary collector, such as a cyclone, is considered integral
to a spray drying system.
9/88 Chemical Process Industry 5.15-3
-------
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EMISSION FACTORS
9/88
-------
References for Section 5.15
1. Air Pollutant Emission Factors, APTD-0923, U. S. Environmental Protection
Agency, Research Triangle Park, NC, April 1970.
2. Air Pollution Engineering Manual, AP-40, U. S. Environmental Protection
Agency, Research Triangle Park, NC, May 1973. Out Of Print.
3. Source Category Survey; Detergent Industry, EPA-450/3-80-030, U. S. Envi-
ronmental Protection Agency, Research Triangle Park, NC, June 1980.
4. A. H. Phelps, "Air Pollution Aspects Of Soap And Detergent Manufacture",
Journal Of The Air Pollution Control Association, _n(8):505-507, August
1967.
5. R. N. Shreve, Chemical Process Industries, Third Edition, New York, McGraw-
Hill, 1967.
6. G. P. Larsen, et al., "Evaluating Sources Of Air Pollution", Industrial And
Engineering Chemistry. 4_5:1070-1074, May 1953.
7. P. Y. McCormick, et al., "Gas-solid Systems", Chemical Engineer's Handbook,
McGraw-Hill Book Company, New York, 1963.
8. Communication from Maryland State Department Of Health, Baltimore, MD,
November 1969.
9. Emission Test Report, Witco Chemical Corporation, Patterson, NJ, EMB-73-
DET-6, U. S. Environmental Protection Agency, Research Triangle Park, NC,
July 1973.
10. Emission Test Report, Lever Brothers, Los Angeles, CA, EMB-73-DET-2, U. S.
Environmental Protection Agency, Research Triangle Park, NC, April 1973.
11. Emission Test Report, Procter and Gamble, Augusta, GA, EMB-72-MM-10, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 1972.
12. Emission Test Report, Procter and Gamble, Long Beach, CA, EMB-73-DET-4,
U. S. Environmental Protection Agency, Research Triangle Park, NC, April
1973.
13. Emission Test Report, Colgate-Palmolive, Jeffersonville, IN, EMB-73-DET-7,
U. S. Environmental Protection Agency, Research Triangle Park, NC, June
1973.
14. Emission Test Report, Lever Brothers, Edgewater, NJ, EMB-72-MM-9, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 1972.
9/88 Chemical Process Industry 5.15-5
-------
6.4 GRAIN ELEVATORS AND PROCESSING PLANTS
6.4.1 General1'3
Grain elevators are facilities at which grains are received, stored, and
then distributed for direct use, process manufacturing, or export. They can
be classified as either "country" or "terminal" elevators, with terminal
elevators further categorized as inland or export (marine) types. Operations
other than storage often are performed at elevators, such as cleaning, drying
and blending. The principal grains handled include wheat, milo, corn, oats,
rice and soybeans.
Country elevators are generally smaller elevators that receive grain by
truck directly from farms during the harvest season. These elevators some-
times clean or dry grain before it is transported to terminal elevators or
processors. Terminal elevators dry, clean, blend and store grain for ship-
ment to other terminals or processors, or for export. These elevators may
receive grain by truck, rail or barge, and they have significantly greater
grain handling and storage capacities than do country elevators. Export
elevators are terminal elevators that load grain primarily onto ships for
export.
The first step at a grain elevator is the unloading of the incoming
truck, railcar or barge. A truck discharges its grain into a hopper, usually
below grade, from which the grain is conveyed to the main part of the eleva-
tor. Barges are unloaded by a bucket elevator (marine leg) that is extended
down into the hold. The main building at an elevator, where grain is elevated
and distributed, is called the "headhouse". In the headhouse, grain is lifted
on one of the elevator legs and discharged onto the gallery belt, which con-
veys the grain to the storage bins, or silos. A "tripper" diverts grain into
the desired bin. Grain is often cleaned and/or dried before storage. When
ready for shipping, grain is discharged from bins onto the tunnel belt below,
which conveys it to the scale garner and on to the desired loadout location.
Figure 6.4-1 illustrates the basic elements of an export terminal elevator.
A grain processing plant (mill) receives grain from an elevator and per-
forms various manufacturing steps that produce a finished food product.
Examples of these plants are flour mills, animal feed mills, and producers of
edible oils, starch, corn syrup, and cereal products. The elevator operations
of unloading, conveying and storing also are performed at mills.
6.4.2 Emissions And Controls1
The only pollutant emitted in significant quantities from grain eleva-
tors and processing operations is particulate matter. Small amounts of
combustion products from natural gas fired grain dryers also may be emitted.
Grain elevators and grain processing operations can be considered separate
categories of the industry when considering emissions.
9/88 Food And Agricultural Industry 6.4-1
-------
01
H
-------
6.4.2.1 Grain Elevators - Emissions of fugitive dust occur whenever quanti-
ties of grain are set into motion during loading, conveying, transfer, drying
or cleaning operations at a grain elevator. The emission rate can be
affected by the quantity of foreign material in the grain (dirt, seeds,
sticks, stones, etc., known as "dockage") and by the type of grain. While it
is difficult to quantify the effect of dockage, observations indicate that
soybeans, oats and sorghum are usually very dusty, whereas wheat and corn are
comparatively clean.4 Total particulate emission factors for the principal
operations at grain elevators are presented in Table 6.4-1. Since data dif-
ferentiating these emission factors by grain type are sparse, all of these
factors are approximate average values intended to apply to a variety of
grains. Tables 6.4-2, 6.4-3 and 6.4-4, and Figures 6.4-2, 6.4-3 and 6.4-4,
show particle size distributions and size specific emission factors for three
operations at grain elevators.
The emission factors in Table 6.4-1 represent the amount of dust genera-
ted per unit weight of grain processed through each uncontrolled operation.
Since the amount of grain passing through each individual operation is often
difficult to determine, it is sometimes convenient to express the emission
factors in terms of the quantity of grain received or shipped by the eleva-
tor. (It is assumed that the amounts shipped and received are equal over the
long run.) Therefore, the factors in Table 6.4-1 have been modified and are
expressed in Table 6.4-5 as a function of the amount of grain received or
shipped. The ratios shown in Table 6.4-5 are approximate values based on
averages for bin turning, cleaning and drying in each elevator category.
However, because operating practices at individual elevators are different,
these ratios, like the emission factors'themselves, may lack precision
when applied to an individual elevator.
The factors in Tables 6.4-1 and 6.4-5 should not be added together in
order to obtain a single overall emission factor for a grain elevator
because, in most elevators, the emissions from some operations are controlled
and others are not. Therefore, emissions estimations generally should be
undertaken for each operation and its associated control device.
Several methods are available to reduce or control dust emissions at
grain elevators. Since most emissions are generated when air passes swiftly
through a mass of grain, measures that slow down grain transfer (conveying)
rates or that reduce free fall distances will reduce emissions. Bulk grain,
especially when falling through the air, should be protected from significant
air currents or wind sources. Many operations at elevators are partially or
totally enclosed (e. g., screw conveyors, drag conveyors, elevator legs) to
isolate generated dust from the atmosphere. Hooding in the vicinity of some
operations (e. g., grain unloading, conveyor transfer points) collects gener-
ated dust by creating a negative pressure area (through suction, or air
aspiration) near the center of activity and then ducting the dusty air to a
control device. Recent developments in the control of ship and' barge loading
operations include the use of "dead boxes" and tent controls. The dead box
is a baffled attachment on the loading spout that serves to reduce the speed
of the falling grain before it reaches the open air and strikes the grain
pile. Aspiration to a control device often accompanies the use of the dead
box. Large flexible covers connected to the loading spout and aspiration
ducting, called tents, are used to cover the holds of ships during most of a
loading operation. The tent must be removed during topping off (usually
9/88 Food And Agricultural Industry 6.4-3
-------
TABLE 6.4-1. TOTAL PARTICULATE EMISSION FACTORS FOR
UNCONTROLLED GRAIN ELEVATORS3
EMISSION FACTOR RATING: B
Type of Operation
Country elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Dryingb
Cleaning0
Headhouse (legs)
Inland terminal elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Dryingb
Cleaning0
Headhouse (legs)
Tripper (gallery belt)
Export elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying13
Cleaning0
Headhouse (legs)
Tripper (gallery belt)
Total particulate
kg/Mg
0.3
0.2
0.5
0.4
1.5
0.8
0.5
0.2
0.7
0.6
1.5
0.8
0.5
0.5
0.5
0.7
0.5
1.5
0.8
0.5
Ib/ton
0.6
0.3
1.0
0.7
3.0
1.5
1.0
0.3
1.4
1.1
3.0
1.5
1.0
1.0
1.0
1.4
1.1
3.0
1.5
1.0
^Expressed as weight of dust emitted/unit weight of grain handled by each
operation. For inland terminal and export elevators, Reference 5; for dry-
Ing, References 2, 6; for country elevators, Reference 5 and additional test
data in References 7-10.
^References 6, 11. Based on 0.9 kg/Mg for uncontrolled rack dryers and 0.15
kg/Mg for uncontrolled column dryers, prorated on the basis of the distribu-
tion of these two types of dryers.
°Reference 11. Average of values, from < 0.3 kg/Mg for wheat to 3.0 kg/Mg
for corn.
6.4-4
EMISSION FACTORS
9/88
-------
TABLE 6.4-2. PARTICLE SIZE DISTRIBUTION AND EMISSION
FACTORS FOR UNCONTROLLED RICE DRYERSa
EMISSION FACTOR RATING: D
Aerodynamic particle Cumulative weight % Emission factor'3
diameter (urn) < stated size (kg/Mg)
2.5
6.0
10.0
15.0
Total particulate
0.8
2.6
7.7
24.5
0.0012
0.0039
0.012
0.037
0.15C
References 1, 12.
^Expressed as cumulative weight of particulate _<_ corresponding
particle size/unit weight of rice dried.
GReference 11.
99.9
11 a,
N "
SO
10 -
UHCONntOLLED
— Utighc p.rc.nc
——— Eali.lon factor
0.0*
0.03 O
0.02 *•
00
09
0.01
2 5 10 20 SO
Particle diameter, urn
100
Figure 6.4-2. Cumulative size distribution and
emission factors for uncontrolled rice dryers.
9/88
Food And Agricultural Industry
6.4-5
-------
TABLE 6.4-3. PARTICLE SIZE DISTRIBUTION AND EMISSION
FACTORS FOR CONTROLLED BARGE UNLOADING/CONVEYING3
EMISSION FACTOR RATING: D
Aerodynamic particle
diameter (urn)
2.5
6.0
10.0
Total particulate
Cumulative weight %
< stated size
4.0
11.0
18.0
Emission factor"
(kg/Mg)
0.00013
0.00037
0.00054
0.003C
aReference 13. Control is by fabric filter.
^Expressed as cumulative weight of particulate £ corresponding
particle size/unit weight of grain unloaded/conveyed.
°Total mass emission factor is from Reference 1.
99.9
•3 »
•O 90
01
50
-------
TABLE 6.4-4. PARTICLE SIZE DISTRIBUTION AND EMISSION
FACTORS FOR UNCONTROLLED SHIPLOADINGa
EMISSION FACTOR RATING: C
Aerodynamic particle
diameter (urn)
2.5
6.0
10.0
15.0
Total particulate
Cumulative weight %
< stated size
10.4
27.0
42.0
53.0
Emission factor*5
(kg/Mg)
0.05
0.13
0.21
0.26
0.50C
References 1, 14-15.
^Expressed as cumulative weight of particulate £ corresponding
particle size/unit weight of grain loaded onto ships.
cReference 11.
n.9
99
£ 95
n
T, »
1)
u
m
4J
n
V
8-« 50
0)
> 10
UKCOMTROLLED
^~ W«ighe p«rctnc
•— EmtMion factor
0.35
0.30
«.» »
n
H»
§
0.20 21
n
rr
O
0.15
30
:s
30
0.10
0.05
2 5 10 20 50 100
Particle diameter, urn
Figure 6.4-4. Cumulative size distribution and
emission factors for uncontrolled shiploading.
9/88
Food And Agricultural Industry
6.4-7
-------
TABLE 6.4-5. TOTAL PARTICULATE EMISSION FACTORS FOR
GRAIN ELEVATORS, BASED ON AMOUNT OF GRAIN RECEIVED OR SHIPPED3
EMISSION FACTOR RATING: C
Type of Operation
Country elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt) ,
Drying4
Cleaning6
Headhouse ( le gs )
Inland terminal elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying"1
Cleaning6
Headhouse (legs)
Tripper (gallery belt)
Export elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drylngd
Cleaning6
Headhouse (legs)
Tripper (gallery belt)
Emission factor,
kg/Mg handled1"
0.3
0.2
0.5
0.4
1.5
0.8
0.5
0.2
0.7
0.6
1.5
0.8
0.5
0.5
0.5
0.7
0.5
1.5
0.8
0.5
X
Typical ratio of grain
processed to grain
received or shlppedc
1.0
1.0
2.1
0.3
0.1
3.1
1.0
1.0
2.0
0.1
0.2
3.0
1.7
1.0
1.0
1.2
0.01
0.2
2.2
l.l
-
Emission factor,
kg/Mg received
or shipped
0.3
0.2
1.0
0.1
0.2
2.5
0.5
0.2
1.4
0.1
0.3
2.3
0.8
0.5
0.5
0.8
0.01
0.3
1.7
0.6
aAssumes amount received is approximately equal to the amount shipped.
'To obtain units of Ib/ton, multiply factors by 2.0.
cReference 6. Average values from a survey of elevators across the U. S.
for any individual elevator or group of elevators In the same locale.
dSee Note b In Table 6.4-1.
eSee Note c In Table 6.4-1.
Can be considerably different
6.4-8
EMISSION FACTORS
9/88
-------
about 25 percent of the total loading), allowing essentially uncontrolled
emissions to escape.
Most elevators utilize particulate control devices on at least some of
their operations. The traditional form of control at elevators has been
mechanical collectors, or cyclones. Cyclones collect particles larger than
about 10 microns with only 85 to 95 percent control efficiency, often
producing visible emissions. Hence, fabric filters are usually selected in
areas having more stringent control requirements. Typical efficiencies for
well operated fabric filters exceed 99 percent, with no visible emissions.
The air aspirated from enclosed equipment and hood's is ducted to a fabric
filter or, in some cases, one or more cyclones. Rarely are other particulate
control devices, such as wet scrubbers and electrostatic precipitators,
applied at elevators. Grain dryers present a different sort of control
problem because of the large volumes of warm, moist air exhausted. Most
dryers are enclosed with a continuously vacuumed polyester or stainless steel
screening to collect particulate, with the vacuum usually discharged to a
cyclone. Two principal dryer configurations, rack and column, are in use.
The majority of dryers manufactured today are of the column type, which has
considerably lower emissions than the rack type.'6
6.4.2.2 Grain Processing Plants - Several grain milling operations, such as
receiving, conveying, cleaning and drying, are similar to those at grain
elevators. In addition to these, breaking down (milling) the grain or grain
by-products for processing through various types of grinding operations is a
further source of emissions. The hammermill is the most widely used grinding
device at feed mills. Product is recovered from the hammermill with a
cyclone collector, which can be a major source of dust emissions. Again,
like elevators, mills use a combination of cyclones and fabric filters to
conserve product and to control emissions. Drying at a. grain mill is accom-
plished using several types of dryers, including fluidized bed dryers (soy-
bean processing) and flash fired or direct fired dryers (corn milling).
These newer dryer types might have lower emissions than the traditional rack
or column dryers, but data are insufficient at this time to quantify the
difference. The grain pre-cleaning often performed before drying also likely
serves to reduce emissions. Emission factors for various grain milling and
other processing operations are presented in Table 6.4-6, and the particle
size distribution and size specific emission factor for a roaster operation
are shown in Table 6.4-7 and Figure 6.4-5. The origins of these emission
factors are discussed below. ,,
Emission factor data for feed mill operations are sparse. The factors
for receiving, shipping and handling are based on estimates made by experts
within the feed industry.17 The remaining feed mill factors are based on test
data in References 2, 18 and 19.
The roasting of carob kibble (or pods), which are ground and used as a
chocolate substitute, is similar to coffee roasting. The emission factor and
particle size distribution for this operation were derived from References 20
and 21.
Three emission areas for wheat mill processing operations are grain
receiving and handling, cleaning house and milling operations. Data from
Reference 5 were used to estimate emission factors for grain receiving and
9/88 Food And Agricultural Industry 6.4-9
-------
TABLE 6.4-6. TOTAL PARTICULATE EMISSION FACTORS FOR
UNCONTROLLED GRAIN PROCESSING OPERATIONSa
EMISSION FACTOR RATING: D
Type of Operation
Feed mills
Receiving
Shipping
Handling
Grinding
Hamme rail li ngb
Flakingb
Crackingb
Pellet coolerb
Carob kibble roasting
Wheat milling
Receiving
Precleanlng and handling
Cleaning house
Mill house
Durum milling
Receiving
Precleaning and handling
Cleaning house
Mill house
Rye milling
Receiving
Precleanlng and handling
Cleaning house
Mill house
e
Oat milling
Rice milling
Receiving
Precleaning and handling
Dryingf
Cleaning and mill house
Emission factor
kg/Mg
1.3
0.5
2.7
O.lc»d
O.ic
0.01c»d
0.2C
3.0
0.5
2.5
-
35.0
0.5
2.5
—
••
0.5
2.5
—
35.0
1.25
0.32
2.5
0.15
—
Ib/ton
2.5
1.0
5.5
0.2c»d
0.2<*
0.02c»d
0.4C
6.0
1.0
5.0
-
70.0
1.0
5.0
—
~
1.0
5.0
—
70.0
2.5
0.64
5.0
0.30
—
6.4-10
EMISSION FACTORS
9/88
-------
TABLE 6.4-6 (concluded).
/
Type of Operation
Soybean milling
Receiving
Handling
Cleaning
DryingS
Cracking and de hulling
Hull grinding
Bean conditioning
Flaking
Meal dryer
Meal cooler
Bulk loading
Dry corn milling
Receiving
Dryingg
Precleaning and handling
Cleaning house
Degerming and milling
Wet corn milling
Receiving
Handling
Cleaning
Dryingh
Bulk loading
Emission factor
kg/Mg
0.8
2.5
-
3.6
1.7
1.0
0.05
0.29
0.75
0.9
0.14
0.5
0.25
2.5
3.0
—
0.5
2.5
3.0
0.24
"
Ib/ton
1.6
5.0
-
7.2
3.3
2.0
0.1
0.57
1.5
1.8
0.27
1.0
0.5
5.0
6.0
—
1.0
5.0
6.0
0.48
m^
emission factors are expressed as weight of dust emitted/unit weight of
grain entering the plant, not necessarily the same as amount of material
processed by each operation. Dash = no data.
^Expressed as weight of dust emitted/unit weight of grain processed.
cWith cyclones.
"Measured on corn processing operations at feed mills.
eRepresents several sources at one plant, some controlled with cyclones and
others with fabric filters.
'Average for uncontrolled column dryers; see Table 6.4-2.
SDryer types unknown.
hFor rotary steam tube dryers.
9/88
Food And Agricultural Industry
6.4-11
-------
TABLE 6.4-7. PARTICLE SIZE DISTRIBUTION AND EMISSION
FACTORS FOR UNCONTROLLED CAROB KIBBLE ROASTERS*
EMISSION FACTOR RATING: E
Aerodynamic particle Cumulative weight % Emission factor*5
diameter (urn) < stated size (kg/Mg)
2.5
6.0
10.0
15.0
Total particulate
0.6
0.7
2.0
11.5
0.018
0.021
0.060
0.35
3.0C
•Reference 18.
^Expressed as cumulative weight of particulate _< corresponding
particle size/unit weight of carob kibble roasted.
Reference 21.
99.9
41
S "
a
«
V
j=
oo
50
10
5
2
1
0.1
0.01
1
imcotmoura
— W.lght p.re.nc
——— Eniuloii ttctat
0.40
0.30 9)
jr
oo
O.IQ
} 10 20 SO 100
Particle diameter, urn
Figure 6.4-5. Cumulative size distribution and
emission factors for uncontrolled carob kibble roasters,
6.4-12
EMISSION FACTORS
9/88
-------
handling. Data for the cleaning house are insufficient to estimate an emis-
sion factor, and information contained in Reference 2 was used to estimate the
emission factor for milling operations. The large emission factor for the
milling operation applies to uncontrolled operations. Almost all of the
sources involved, however, are equipped with control devices to prevent
product losses. Fabric filters are widely used for this purpose.
Durum and rye milling operations are similar to those for wheat milling.
Therefore, most of these emission factors are assumed equal to those for
wheat mill operations.
The grain unloading, handling and cleaning operations for dry corn mill-
ing are similar to those in other grain mills, but the subsequent operations
are somewhat different. Also, some drying of corn received at the mill may
be necessary before storage. An estimate of the emission factor for drying
was obtained from Reference 2. Insufficient information is available to
estimate emission factors for degerming and milling.
Information necessary to estimate emissions from oat milling is unavail-
able, and no emission factors for other grains are considered applicable
because oats are reported to be dustier than many other grains. The only
emission factor data available are for controlled emissions.
Emission factors for rice milling are based on those for similar opera-
tions in other grain handling facilities. Insufficient information is avail-
able to estimate emission factors for drying, cleaning and mill house
operations.
Information contained in Reference 2 is used to estimate emission factors
for soybean mills.
Emissions information on wet corn milling is generally unavailable, in
part because of the wide variety of products and the diversity of operations.
Receiving, handling and cleaning operations emission factors are assumed to
be similar to those for dry corn milling. The drying emission factor is from
tests at a wet corn milling plant producing animal feed.22
Due to operational similarities between grain milling and processing
plants and grain elevators, the control methods used are similar. Both often
use cyclones or fabric filters to control emissions from the grain handling
operations (e.g., unloading, legs, cleaners, etc.). These same devices are
also often used to control emissions from other processing operations. A
good example of this is the extensive use of fabric filters in flour mills.
However, there are also certain operations within some milling operations
that are not amenable to the use of these devices. Therefore, wet scrubbers
have found some application, particularly where the effluent gas stream has a
high moisture content. Certain other operations have been found to be
especially difficult to control, such as rotary dryers in wet corn mills.
The various emission control systems that have been applied to operations
within the grain milling and processing industry are described in Reference
2.
9/88 Food And Agricultural Industry 6.4-13
-------
References for Section 6.4
1. G. A. LaFlam, Documentation for AP-42 Emission Factors; Section 6.4,
Grain Elevators and Processing Plants, Pacific Environmental Services,
Inc., Durham, NO, September 1987.
2. L. J. Shannon, et al., Emissions Control in the Grain and Feed Industry,
Volume I - Engineering and Cost Study, EPA-450/3-73-003a, U. S. Environ-
mental Protection Agency, Research Triangle Park, NC, December 1973.
3. The Storage and Handling of Grain, PEI, Inc., Cincinnati, OH, for
U. S. EPA Region V, Contract No. 68-02-1355, March 1974.
4. Technical Guidance for Control of Industrial Process Fugitive Particu-
late Emissions, PEI, Inc., for U. S. Environmental Protection Agency,
Research Triangle Park, NC, Contract No. 68-02-1375, March 1977.
5. P. G. Gorman, Potential Dust Emission from a Grain Elevator in Kansas
City, Missouri, MRI for U. S. Environmental Protection Agency, Research
Triangle Park, NC, Contract No. 68-02-0228, May 1974.
6. L. J. Shannon, et al., Emission Control in the Grain and Feed Industry,
Volume II - Emission Inventory, EPA-450/3-73-003b, MRI for U. S.
Environmental Protection Agency, Research Triangle Park, NC, September
1974.
7. W. H. Maxwell, Stationary Source Testing of a Country Grain Elevator at
Overbrook, Kansas, MRI for U. S. Environmental Protection Agency,
Research Triangle Park, NC, Contract No. 68-02-1403, February 1976.
8. W. H. Maxwell, Stationary Source Testing of a Country Grain Elevator at
Great Bend, Kansas, MRI for U. S. Environmental Protection Agency,
Research Triangle Park, NC, Contract No. 68-02-1403, April 1976.
9. F. J. Beigea, Cyclone Emissions and Efficiency Evaluation, (Tests at
elevators in Edinburg and Thompson, North Dakota), Pollution Curbs,
Inc., St. Paul, MN, March 10, 1972.
10. F. J. Belgea, Grain Handling Dust Collection Systems Evaluation for
Farmer's Elevator Company, Minot, North Dakota, Pollution Curbs, Inc.,
St. Paul, MN, August 28, 1972.
11. M. P. Schrag, et al., Source Test Evaluation for Feed and Grain Indus-
try, EPA-450/3-76-043, U. S. Environmental Protection Agency, Research
Triangle Park, NC, December 1976.
12. Emission test data from Environmental Assessment Data Systems, Fine
Particle Emission Information System (FPEIS), Series No. 228, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 1983.
13. Air Pollution Emission Test, Bunge Corporation, Destrehan, LA, EMB-
74-GRN-7, U. S. Environmental Protection Agency, Research Triangle Park,
NC, January 1974.
6.4-14 EMISSION FACTORS 9/88
-------
14. W. Battye and R. Hall, Particulate Emission Factors and Feasibility of
Emission Controls for Shiploading Operations at Portland, Oregon Grain
Terminals, Volume I, GCA Corporation, Bedford, MA, June 1979.
15. Emission Factor Development for Ship and Barge Loading of Grain, GCA
Corporation for U. S. Environmental Protection Agency, Research Triangle
Park, NC, Contract No. 68-02-3510, October 1984.
16. J. M. Appold, "Dust Control for Grain Dryers," in Dust Control for Grain
Elevators, presented before the National Grain and Feed Association, St.
Louis, MO, May 7-8, 1981.
17. Written communication from D. Bossman, American Feed Industry Associa-
tion, Arlington, VA, to F. Noonan, U. S. Environmental Protection
Agency, Research Triangle Park, NC, July 24, 1987.
18. Written communication from P. Luther, Purina Mills, Inc., St. Louis, MO,
to G. LaFlam, PES, Inc., Durham, NC, March 11, 1987.
19. Written communication from P. Luther, Purina Mills, Inc., St. Louis, MO,
to F. Noonan, U. S. Environmental Protection Agency, Research Triangle
Park, NC, July 8, 1987.
20. Emission test data from FPEIS Series No. 229, U. S. Environmental
Protection Agency, Research Triangle Park, NC, June 1983.
21. H. J. Taback, Fine Particle Emissions from Stationary and Miscellaneous
Sources in the South Coast Air Basin, KVB, Inc., Tustin, CA, for the
California Air Resources Board, February 1979.
22. Source Category Survey; Animal Feed Dryers, EPA-450/3-81-017, U. S.
Environmental Protection Agency, Research Triangle Park, NC, December
1981.
9/88 Food And Agricultural Industry 6.4-15
-------
About 10 percent of all lime produced is converted to hydrated (slaked)
lime. There are two kinds of hydrators, atmospheric and pressure. Atmo-
spheric hydrators, the more prevalent type, are used in continuous mode to
produce high calcium and normal dolomitic hydrates. Pressure hydrators, on
the other hand, produce only a completely hydrated dolomitic lime and oper-
ate only in batch mode. Generally, water sprays or wet scrubbers perform
the hydrating process, to prevent product loss. Following hydration, the
product may be milled and then conveyed to air separators for further drying
and removal of coarse fractions.
In the United States, lime plays a major role in chemical and metal-
lurgical operations. Two of the largest uses are as steel flux and in
alkali production. Lesser uses include construction, refractory and agri-
cultural applications.
8.15.2 Emissions And Controls3'5
Potential air pollutant emission points in lime manufacturing plants
are shown in Figure 8.15-1. Except for gaseous pollutants emitted from
kilns, particulate is the only pollutant of concern from most of the opera-
tions .
The largest ducted source of particulate is the kiln. Of the various
kiln types, fluidized beds have the most uncontrolled particulate emissions,
because of the very small feed size combined with high air flow through
these kilns. Fluidized bed kilns are well controlled for maximum product
recovery. The rotary kiln is second worst in uncontrolled particulate emis-
sions, also because of the small feed size and relatively high air veloci-
ties and dust entrainment caused by the rotating chamber. The calcimatic
(rotary hearth) kiln ranks third in dust production, primarily because of
the larger feed size and the fact that, during calcination, the limestone
remains stationary relative to the hearth. The vertical kiln has the lowest
uncontrolled dust emissions, due to the large lump feed and the relatively
low air velocities and slow movement of material through the kiln.
Some sort of particulate control is generally applied to most kilns.
Rudimentary fallout chambers and cyclone separators are commonly used for
control of the larger particles. Fabric and gravel bed filters, wet (com-
monly venturi) scrubbers, and electrostatic precipitators are used for sec-
ondary control.
Nitrogen oxides, carbon monoxide and sulfur oxides are all produced in
kilns, although the last are the only gaseous pollutant emitted in signifi-
cant quantities. Not all of the sulfur in the kiln fuel is emitted as sul-
fur oxides, since some fraction reacts with the materials in the kiln. Some
sulfur oxide reduction is also effected by the various equipment used for
secondary particulate control.
Product coolers are emission sources only when some of their exhaust
gases are not recycled through the kiln for use as combustion air. The
10/86 Mineral Products Industry 8.15-3
-------
trend is away from the venting of product -cooler exhaust, however, to maxi-
mize fuel use efficiencies. Cyclones, baghouses and wet scrubbers have been
employed on coolers for particulate control.
Hydrator emissions are low; because water sprays or wet scrubbers are
usually installed to prevent product loss in the exhaust gases. Emissions
from pressure hydrators may be higher than from the more common atmospheric
hydrators, because the exhaust gases are released intermittently, making
control more difficult.
Other particulate sources in lime plants include primary and secondary
crushers, mills, screens, mechanical and pneumatic transfer operations,
storage piles, and roads. If quarrying is a part of the lime plant opera-
tion, particulate may also result from drilling and blasting. Emission
factors for some of these operations are presented in Sections 8.19 and 11.2
of this document.
Controlled and uncontrolled emission factors and particle size data for
lime manufacturing are given in Tables 8.15-1 through 8.15-3. The size dis-
tributions of particulate emissions from controlled and uncontrolled rotary
kilns and uncontrolled product loading operations are shown in Figures
8.15-2 and 8.15-3.
8.15-4 EMISSION FACTORS 10/86
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8.19.2 CRUSHED STONE PROCESSING
8.19.2.1 Process Description1
Major rock types processed by the rock and crushed stone industry include
limestone, dolomite, granite, traprock, sandstone, quartz and quartzite. Minor
types include calcareous marl, marble, shell and slate. Industry classifica-
tions vary considerably and, in many cases, do not reflect actual geological
definitions.
Rock and crushed stone products generally are loosened by drilling and
blasting, then are loaded by power shovel or front end loader and transported
by heavy earth moving equipment. Techniques used for extraction vary with the
nature and location of the deposit. Further processing may include crushing,
screening, size classification, material handling, and storage operations. All
of these processes can be significant sources of dust emissions if uncontrolled.
Some processing operations also include washing, depending on rock type and
desired product.
Quarried stone normally is delivered to the processing plant by truck and
is dumped into a hoppered feeder, usually a vibrating grizzly type, or onto
screens, as illustrated in Figure 8.19.2-1. These screens separate or scalp
large boulders from finer rocks that do not require primary crushing, thus
reducing the load to the primary crusher. Jaw, or gyratory, crushers are
usually used for initial reduction. The crusher product, normally 7.5 to 30
centimeters (3 to 12 inches) in diameter, and the grizzly throughs (undersize
material) are discharged onto a belt conveyor and usually are transported either
to secondary screens and crushers or to a surge pile for temporary storage.
Further screening generally separates the process flow into either two
or three fractions (oversize, undersize and throughs) ahead of the secondary
crusher. The oversize is discharged to the secondary crusher for further
reduction, and the undersize usually bypasses the secondary crusher. The
throughs sometimes are separated, because they contain unwanted fines, and are
stockpiled as crusher run material., Gyratory crushers or cone crushers are
commonly used for secondary crushing, although impact crushers are sometimes
found.
The product of the secondary crushing stage, usually 2.5 centimeters (1
inch) diameter or less, is transported to secondary screens for further sizing.
Oversize material is sent back for recrushing. Depending on rock type and
desired product, tertiary crushing or grinding may be necessary, usually using
cone crushers or hammermills. (Rod mills, ball mills and hammer mills normally
are used in milling operations, which are not considered a part of the construc-
tion aggregate industry.) The product from tertiary crushing may be conveyed
to a classifier, such as a dry vibrating screen system, or to an air separator.
Any oversize is returned to the tertiary crusher for further reduction. At this
point, end products of the desired grade are conveyed or trucked directly to
finished product bins or to open area stockpiles.
9/88 Mineral Products Industry 8.19.2-1
-------
FIGURE 8.19.2-1. Typical stone processing plant.
8.19.2-2
EMISSION FACTORS
9/88
-------
In certain cases, stone washing is required to meet particular end product
specifications or demands, as with concrete aggregate processing. Crushed and
broken stone normally are not milled but are screened and shipped to the con-
sumer after secondary or tertiary crushing.
8.19.2.2 Emissions And Controls1'3
Dust emissions occur from many operations in stone quarrying and pro-
cessing. A substantial portion of these emissions consists of heavy particles
that may settle out within the plant. As in other operations, crushed stone
emission sources may be categorized as either process sources or fugitive dust
sources. Process sources include those for which emissions are amenable to
capture and subsequent control. Fugitive dust sources generally involve the
reentrainment of settled dust by wind or machine movement. Factors affecting
emissions from either source category include the type, quantity and surface
moisture content of the stone processed; the type of equipment and operating
practices employed; and topographical and climatic factors.
Of geographic and seasonal factors, the primary variables affecting uncon-
trolled particulate emissions are wind and material moisture content. Wind
parameters vary with geographical location, season and weather. It can be
expected that the level of emissions from unenclosed sources (principally fugi-
tive dust sources) will be greater during periods of high winds. The material
moisture content also varies with geographic location, season and weather.
Therefore, the levels of uncontrolled emissions from both process emission
sources and fugitive dust sources generally will be greater in arid regions
of the country than in temperate ones, and greater during the summer months
because of a higher evaporation rate.
The moisture content of the material processed can have a substantial
effect on uncontrolled emissions. This is especially evident during mining,
initial material handling, and initial plant process operations such as primary
crushing. Surface wetness causes fine particles to agglomerate on, or to adhere
to, the faces of larger stones, with a resulting dust suppression effect. How-
ever, as new fine particles are created by crushing and attrition, and as the
moisture content is reduced by evaporation, this suppressive effect diminishes
and may disappear. Depending on the geographic and climatic conditions, the
moisture content of mined rock may range from nearly zero to several percent.
Since moisture content is usually expressed on a basis of overall weight per-
cent, the actual moisture amount per unit area will vary with the size of the
rock being handled. On a constant mass fraction basis, the per unit area mois-
ture content varies inversely with the diameter of the rock. Therefore, the
suppressive effect of the moisture depends on both the absolute mass water con-
tent and the size of the rock product. Typically, a wet material will contain
1.5 to 4 percent water or more.
There are a large number of material, equipment and operating factors
which can influence emissions from crushing. These include: (1) rock type,
(2) feed size and distribution, (3) moisture content, (4) throughput rate, (5)
crusher type, (6) size reduction ratio, and (7) fines content. Insufficient
data are available to present a matrix of rock crushing emission factors
detailing the above classifications and variables. Data available from which
to prepare emission factors also vary considerably, for both extractive testing
and plume profiling. Emission factors from extractive testing are generally
9/88 Mineral Products Industry 8.19.2-3
-------
higher than those based upon plume profiling tests, but they have a greater
degree of reliability. Some test data for primary crushing indicate higher
emissions than from secondary crushing, although factors affecting emission
rates and visual observations suggest that the secondary crushing emission
factor, on a throughput basis, should be higher. Table 8.19.2-1 shows single
factors for either primary or secondary crushing reflecting a combined data
base. An emission factor for tertiary crushing is given, but it is based on
extremely limited data. All factors are rated low because of the limited and
highly variable data base.
TABLE 8.19.2-1.
UNCONTROLLED PARTICIPATE EMISSION FACTORS
FOR CRUSHING OPERATIONS3
Type of crushing'3
Primary or secondary
Dry material
Wet material0
Tertiary dry materiald
Partici
< 30 urn
kg/Mg (Ib/ton)
0.14 (0.28)
0.009 (0.018)
0.93 (1.85)
ilate
< 10 urn
kg/Mg (Ib/ton)
0.0085 (0.017)
-
-
Emission
Factor
Rating
D
D
E
aBased on actual feed rate of raw material entering the particular operation.
Emissions will vary by rock type, but data available are insufficient to
characterize these phenomena. Dash = no data.
^References 4-5. Typical control efficiencies for cyclone, 70 - 80%;
fabric filter, 99%; wet spray systems, 70 - 90%.
References 5-6. Refers to crushing of rock either naturally wet or
moistened to 1.5 - 4 weight % with wet suppression techniques.
of values used to calculate emission factor is 0.0008 - 1.38 kg/Mg.
Emission factor estimates for stone quarry blasting operations are not
presented here because of the sparsity and unreliability of available test
data. While a procedure for estimating blasting emissions is presented in
Section 8.24, Western Surface Coal Mines, that procedure should not be applied
to stone quarries because of dissimilarities in blasting techniques, material
blasted and size of blast areas.
There are no screening emission factors presented in this Section. How-
ever, the screening emission factors given in Section 8.19.1, Sand and Gravel
Processing, should be similar to those expected from screening crushed rock.
Milling of fines is also not included in this Section as this operation is
normally associated with non construction aggregate end uses and will be covered
elsewhere in the future when information is adequate.
Open dust source (fugitive dust) emission factors for stone quarrying and
processing are presented in Table 8.19.2-2. These factors have been determined
8.19.2-4
EMISSION FACTORS
9/88
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through tests at various quarries and processing plants.""' The single valued
open dust emission factors given in Table 8.19.2-2 may be used when no other
information exists. Empirically derived emission factor equations presented
in Section 11.2 of this document are preferred and should be used when possible.
Because these predictive equations allow the adjustment of emission factors for
specific source conditions, these equations should be used instead of those in
Table 8.19.2-2, whenever emission estimates applicable to specific stone quarry-
ing and processing facility sources are needed. Chapter 11.2 provides measured
properties of crushed limestone, as required for use in the predictive emission
factor equations.
References for Section 8.19.2
1. Air Pollution Control Techniques for Nonmetallic Minerals Industry,
EPA-450/3-82-014, U. S. Environmental Protection Agency, Research
Triangle Park, NC, August 1982.
2. P. K. Chalekode, et al., Emissions from the Crushed Granite Industry;
State of the Art, EPA-600/2-78-021, U. S. Environmental Protection
Agency, Washington, DC, February 1978.
3. T. R. Blackwood, et al., Source Assessment: Crushed Stone, EPA-600/2-78-
004L, U. S. Environmental Protection Agency, Washington, DC, May 1978.
4. F. Record and W. T. Harnett, Particulate Emission Factors for the
Construction Aggregate Industry, Draft Report, GCA-TR-CH-83-02, EPA
Contract No. 68-02-3510, GCA Corporation, Chapel Hill, NC, February 1983.
5. Review Emission Data Base and Develop Emission Factors for the Con-
struction Aggregate Industry, Engineering-Science, Inc., Arcadia, CA,
September 1984.
6. C. Cowherd, Jr., et al., Development of Emission Factors for Fugitive Dust
Sources, EPA-450/3-74-037, U. S. Environmental Protection Agency, Research
Triangle Park, NC, June 1974.
7. R. Bonn, et al., Fugitive Emissions from Integrated Iron and Steel Plants,
EPA-600/2-78-050, U. S. Environmental Protection Agency, Washington, DC,
March 1978.
8.19.2-6 EMISSION FACTORS 9/88
-------
8.24 WESTERN SURFACE COAL MINING
8.24.1 General1
There are 12 major coal fields in the western states (excluding the
Pacific Coast and Alaskan fields), as shown in Figure 8.24-1. Together,
they account for more than 64 percent of the surface minable coal reserves
COAL TYPE
LIGNITE GSS
SUBBITUMINOUSCZ3
BITUMINOUS
1
2
3
4
5
6
7
8
9
10
11
12
Coal field
Fort Union
Powder Riv«r
North Central
Bighorn B«»ln
Wind River
Haas Fork
Uinta
Southwestern Utah
San Juan River
Raton Meea
Denver
Green River
Scrippable rese
(ID6 tons)
23,529
S6.727
All underground
All underground
3
1,000
308
224
2,318
All underground
All underground
2,120
9/88
Figure 8.24-1. Coal fields of the western U.S.3
Mineral Products Industry
8.24-1
-------
in the United States.2 The 12 coal fields have varying characteristics
which may influence fugitive dust emission rates from mining operations,
including overburden and coal seam thicknesses and structure, mining equip-
ment, operating procedures, terrain, vegetation, precipitation and surface
moisture, wind speeds and temperatures. The operations at a typical west-
ern surface mine are shown in Figure 8.24-2. All operations that involve
movement of soil, coal, or equipment, or exposure of erodible surfaces,
generate some amount of fugitive dust.
The initial operation is removal of topsoil and subsoil with large
scrapers. The topsoil is carried by the scrapers to cover a previously
mined and regraded area as part of the reclamation process or is placed in
temporary stockpiles. The exposed overburden, the earth which is between
the topsoil and the coal seam, is leveled, drilled and blasted. Then the
overburden material is removed down to the coal seam, usually by a dragline
or a shovel and truck operation. It is placed in the adjacent mined cut,
forming a spoils pile. The uncovered coal seam is then drilled and
blasted. A shovel or front end loader loads the broken coal into haul
trucks, and it is taken out of the pit along graded haul roads to the tip-
ple, or truck dump. Raw coal sometimes may be dumped onto a temporary
storage pile and later rehandled by a front end loader or bulldozer.
At the tipple, the coal is dumped into a hopper that feeds the primary
crusher, then is conveyed through additional coal preparation equipment
such as secondary crushers and screens to the storage area. If the mine
has open storage piles, the crushed coal passes through a coal stacker onto
the pile. The piles, usually worked by bulldozers, are subject to wind
erosion. From the storage area, the coal is conveyed to a train loading
facility and is put into rail cars. At a captive mine, coal will go from
the storage pile to the power plant.
During mine reclamation, which proceeds continuously throughout the
life of the mine, overburden spoils piles are smoothed and contoured by
bulldozers. Topsoil is placed on the graded spoils, and the land is pre-
pared for revegetation by furrowing, mulching, etc. From the time an area
is disturbed until the new vegetation emerges, all disturbed areas are sub-
ject to wind erosion.
8.24.2 Emissions
Predictive emission factor equations for open dust sources at western
surface coal mines are presented in Tables 8.24-1 and 8.24-2. Each equa-
tion is for a single dust generating activity, such as vehicle traffic on
unpaved roads. The predictive equation explains much of the observed vari-
ance in emission factors by relating emissions to three sets of source pa-
rameters: 1) measures of source activity or energy expended (e.g., speed
and weight of a vehicle traveling on an unpaved road); 2) properties of the
material being disturbed (e.g., suspendable fines in the surface material
of an unpaved road); and 3) climate (in this case, mean wind speed).
The equations may be used to estimate particulate emissions generated
per unit of source extent (e.g., vehicle distance traveled or mass of mate-
rial transferred).
8.24-2 EMISSION FACTORS 9/88
-------
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Mineral Products Industry
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Mineral Products Industry
8.24-5
-------
The equations were developed through field sampling of various western surface
mine types and are thus applicable to any of the surface coal mines located in
the western United States.
In Tables 8.24-1 and 8.24-2, the assigned quality ratings apply within
the ranges of source conditions that were tested in developing the equations,
given in Table 8.24-3. However, the equations are derated one letter value
(e. g., A to B) if applied to eastern surface coal mines.
TABLE 8.24-3.
TYPICAL VALUES FOR CORRECTION FACTORS APPLICABLE TO THE
PREDICTIVE EMISSION FACTOR EQUATIONS3
Number
Source Correction of test
factor samples
Coal loading
Bulldozers
Coal
Overburden
Dragline
Scraper
Grader
Light/medium
duty vehicle
Haul truck
Moisture
Moisture
Silt
Moisture
Silt
Drop distance
H «
Moisture
Silt
Weight
Speed
t*
Moisture
Wheels
Silt loading
it it
7
3
3
8
8
19
7
10
15
7
7
29
26
Range Geometric
mean
6.6 -
4.0 -
6.0 -
2.2 -
3.8 -
1.5 -
5 -
0.2 -
7.2 -
33 -
36 -
8.0 -
5.0 -
0.9 -
6.1 -
3.8 -
34 -
38
22.0
11.3
16.8
15.1
30
100
16.3
25.2
64
70
19.0
11.8
1.7
10.0
254
2270
17.8
10.4
8.6
7.9
6.9
8.6
28.1
3.2
16.4
48.8
53.8
11.4
7.1
1.2
8.1
40.8
364
Units
%
%
%
%
%
m
ft
%
%
Mg
ton
kph
mph
%
number
g/m2
Ib/ac
aReference
In using the equations to estimate emissions from sources found in a
specific western surface mine, it is necessary that reliable values for
correction parameters be determined for the specific sources of interest,
if the assigned quality ranges of the equations are to be applicable.
For example, actual silt content of coal or overburden measured at a facility
8.24-6
EMISSION FACTORS
9/88
-------
should be used instead of estimated values. In the, event that site spe-
cific values for correction parameters cannot be obtained, the appropriate
geometric mean values from Table 8.24-3 may be used, but the assigned qual-
ity rating of each emission factor equation is reduced by one level (e.g.,
A to B).
Emission factors for open dust sources not covered in Table 8.24-3 are
in Table 8.24-4. These factors were determined through source testing at
various western coal mines.
The factors in Table 8.24-4 for mine locations I through V were devel-
oped for specific geographical areas. Tables 8.24-5 and 8.24-6 present
characteristics of each of these mines (areas). A "mine specific" emission
factor should be used only if the characteristics of the mine for which an
emissions estimate is needed are very similar to those of the mine for
which the emission factor was developed. The other (nonspecific) emission
factors were developed at a variety of mine types and thus are applicable
to any western surface coal mine.
As an alternative to the single valued emission factors given in Table
8.24-4 for train or truck loading and for truck or scraper unloading, two
empirically derived emission factor equations are presented in Section
11.2.3 of this document. Each equation was developed for a source opera-
tion (i.e., batch drop and continuous drop, respectively), comprising a
single dust generating mechanism which crosses industry lines.
Because the predictive equations allow emission factor adjustment to
specific source conditions, the equations should be used in place of the
factors in Table 8.24-4 for the sources identified above, if emission esti-
mates for a specific western surface coal mine are needed. However, the
generally higher quality ratings assigned to the equations are applicable
only if 1) reliable values of correction parameters have been determined
for the specific sources of interest and 2) the correction parameter values
lie within the ranges tested in developing the equations. Table 8.24-3
lists measured properties of aggregate materials which can be used to esti-
mate correction parameter values for the predictive emission factor equa-
tions in Chapter 11, in the event that site specific values are not avail-
able. Use of mean correction parameter values from Table 8.24-3 reduces
the quality ratings of the emission factor equations in Chapter 11 by one
level.
9/88 Mineral Products Industry 8.24-7
-------
TABLE 8.24-4. UNCONTROLLED PARTICULATE EMISSION FACTORS FOR
OPEN DUST SOURCES AT WESTERN SURFACE COAL MINES
Source
Drilling
Toptoil raovtl by
scraper
Overburden
replacement
Truck loading by
power ihovel
(batch drop)c
Train loading (batch
or continuous drop)
Bottoai duap truck
unloading
(batch drop)c
End du*rp truck
unloading
(batch drop)
Scraper unloading
(batch drop)
Wind erosion of
exposed areas
Material Mine
location
Overburden Any
Coal V
Topsoil Any
IV
Overburden Any
Overburden V
Coal Any
III
Overburden V
Coal IV
II!
II
I
Any
Coal V
Topsoil IV
Seeded land, Any
stripped over*
burden , graded
overburden
TSP
emission
factor
1.3
O.S9
0.22
0.10
0.058
0.029
0.44
0.22
0.012
0.0060
0.037
0.018
0.028
0.014
0.0002
0.0001
0.002
0.001
0.027
0.014
0.005
0.002
0.020
0.010
0.014
0.0070
0.066
0.033
0.007
0.004
0.04
0.02
0.38
0«K
• OJ
Emission
Units Factor
Rating
Ib/bolr
kg/hole
Ib/hole
kg/hole
Ib/T
kg/Mg
Ib/T
kg/Bg
Ib/T
k*/Mg -
Ib/T
kg/Ml
Ib/T
kg/Hi
Ib/T
kg/Hg
Ib/T
«8/T
Ib/T
kg/Hg
Ib/T
kg/Hg
Ib/T
kg/Mg
Ib/T
k*/Hg
Ib/T
kg/Mg
Ib/T
kg/Hg
Ib/T
kg/Hg
T
(acrc)(yz)
ttt
(hectare)Cyr)
B
B
t
E
E
E
D
0
C
C
C
C
D
D
D
0
E
E
E
E
E
E
E
E
D
D
D
D
E
E
C
C
C
Rostan numerals I through V refer to specific nine locations for whicn the
corresponding emission factors were developed (Reference 4). Table* 8.24-4
and 8.24-5 present characteristics of each of these axnes. See text, for
correct use of these "sane specific" emission factors. The other factors
(frosi Reference S except for overburden drilling frosi Reference 1) can be
applied to any western surface coal nine.
Total suspended particulate (TSP) denotes what is measured by a standard high
volume sampler (see Section 11.2).
Predictive emission factor equations, which generally provide store accurate
estimates of emissions, are presented in Chapter 11.
8.24-8
EMISSION FACTORS
9/88
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Mineral Products Industry
8.24-9
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References for Section 8.24
1. K. Axetell and C. Cowherd, Improved Emission Factors for Fugitive Dust
from Western Surface Coal Mining Sources, 2 Volumes, EPA Contract No.
68-03-2924, U. S. Environmental Protection Agency, Cincinnati, OH,
July 1981.
2. Reserve Base of U. S. Coals by Sulfur Content; Part 2, The Western
States, IC8693, Bureau of Mines, U. S. Department of the Interior,
Washington, DC, 1975.
3. Bituminous Coal and Lignite Production and Mine Operations - 1978,
DOE/EIA-0118(78), U.S. Department of Energy, Washington, DC, June
1980.
4. K. Axetell, Survey of Fugitive Dust from Coal Mines, EPA-908/1-78-003,
U. S. Environmental Protection Agency, Denver, CO, February 1978.
5. I*. L. Shearer, et al., Coal Mining Emission Factor Development and
Modeling Study, Araax Coal Company, Carter Mining Company, Sunoco
Energy Development Company, Mobil Oil Corporation, and Atlantic
Richfield Company, Denver, CO, July 1981.
9/88 Mineral Products Industry 8.24-11
-------
CHAPTER 11. MISCELLANEOUS SOURCES
This chapter contains emission factor information on those source cate-
gories that differ substantially from, and hence cannot be grouped with, the
other "stationary" sources discussed in this publication. These miscellaneous
emitters, both natural and manmade, are almost exclusively area sources, with
their pollutant generating process(es) dispersed over large land areas. Another
characteristic of these sources is the inapplicability, in most cases, of con-
ventional control methods, such as wet/dry equipment, fuel switching, process
changes, etc. Instead, control of these emissions, where possible at all, may
include such techniques as modification of agricultural burning practices,
paving with asphalt or concrete, or stabiliation of dirt roads. Finally,
miscellaneous sources generally emit pollutants intermittently, when compared
to most stationary point sources. For example, a wildfire may emit large
quantities of particulate and carbon monoxide for several hours or even days.
But, when measured against a continuous emitter, such as a sulfuric acid plant,
over a long period of time, its emissions may seem relatively minor. Effects
on air quality may also be of relatively short duration.
9/88 Miscellaneous Sources 11-1
-------
11.1 Wildfires And Prescribed Burning
11.1.1 General1
A wildfire is a large scale natural combustion process that consumes
various ages, size and types of flora growing outdoors in a geographical area.
Consequently, wildfires are potential sources of large amounts of air pollut-
ants that should be considered when trying to relate emissions to air quality.
The size and intensity, even the occurrence, of a wildfire depend
directly on such variables as meteorological conditions, the species of vege-
tation involved and their moisture content, and the weight of consumable fuel
per acre (available fuel loading). Once a fire begins, the dry combustible
material is consumed first. If the energy release is large and of sufficient
duration, the drying of green, live material occurs, with subsequent burning
of this material as well. Under proper environmental and fuel conditions,
this process may initiate a chain reaction that results in a widespread
conflagration.
The complete combustion of wildland fuels (forests, grasslands, wetlands)
require a heat flux (temperature gradient), adequate oxygen supply, and
sufficient burning time. The size and quantity of wildland fuels, meteo-
rological conditions, and topograhic features interact to modify the burning
behavior as the fire spreads, and the wildfire will attain different degrees
of combustion efficiency during its lifetime.
The importance of both fuel type and fuel loading on the fire process
can not be overemphasized. To meet the pressing need for this kind of infor-
mation, the U. S. Forest Service is developing a model of a nationwide fuel
identification system that will provide estimates of fuel loading by size
class. Further, the environmental parameters of wind, slope and expected
moisture changes have been superimposed on this fuel model and incorporated
into a National Fire Danger Rating System (NFDRS). This system considers
five classes of fuel, the components of which are selected on the basis of
combustibility, response of dead fuels to moisture, and whether the living
fuels are herbaceous (grasses, brush) or woody (trees, shrubs).
Most fuel loading figures are based on values for "available fuel," that
is, combustible material that will be consumed in a wildfire under specific
weather conditions. Available fuel values must not be confused with corres-
ponding values for either "total fuel" (all the combustible material that
would burn under the most severe weather and burning conditions) or "potential
fuel" (the larger woody material that remains even after an extremely high
intensity wildfire). It must be emphasized, however, that the various methods
of fuel identification are of value only when they are related to the existing
fuel quantity, the quantity consumed by the fire, and the geographic area and
conditions under which the fire occurs.
For the sake of conformity and convenience, fuel loadings are estimated
for the vegetation in the U. S. Forest Service Regions are presented in
Table 11.1-1. Figure 11.1-1 illustrates these areas and regions.
9/88 Miscellaneous Sources 11.1-1
-------
TABLE 11.1-1. SUMMARY OF ESTIMATED FUEL CONSUMED BY WILDFIRES*
National region*'
Rocky Mountain
Region 1: Northern
Region 2: Rocky Mountain
Region 3: Southwestern
Region 4: Intermountain
Pacific
Region 5: California
Region 6: Pacific Northwest
Region 10: Alaska
Coastal
Interior
Southern
Region 8: Southern
Eastern
North central
Region 9: Conifers
Ha rdwo ods
Estimated average fuel loading
Mg/hectare
83
135
67
22
40
43
40
135
36
135
25
20
20
25
25
22
27
ton/acre
37
60
30
10
8
19
18
60
16
60
11
9
9
11
11
10
12
aReference 1.
Figure 11.1-1 for region boundaries
11.1-2
EMISSION FACTORS
9/88
-------
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9/88
Miscellaneous Sources
11.1-3
-------
11.1.2 Emissions And Controls*
It has been hypothesized, but not proven, that the nature and amounts of
air pollutant emissions are directly related to the intensity and direction
(relative to the wind) of the wildfire, and are indirectly related to the rate
at which the fire spreads. The factors that affect the rate of spread are
(1) weather (wind velocity, ambient temperature, relative humidity); (2) fuels
(fuel type, fuel bed array, moisture content, fuel size); and (3) topography
(slope and profile). However, logistical problems (such as size of the burning
area) and difficulties in safely situating personnel and equipment close to the
fire have prevented the collection of any reliable emissions data on actual
wildfires, so that it is not possible to verify or disprove the hypothesis.
Therefore, until such measurements are made, the only available information is
that obtained from burning experiments in the laboratory. These data, for both
emissions and emission factors, are contained in Table 11.1-2. It must be
emphasized that the factors presented here are adequate for laboratory scale
emissions estimates, but that substantial errors may result if they are used to
calculate actual wildfire emissions.
The emissions and emission factors displayed in Table 11.1-2 are calculated
using the following formulas:
*i - P£L (1)
Pi LA (2)
where: F^ - Emission factor (mass of pollutant/unit area of
forest consumed)
P! - Yield for pollutant "i" (mass of pollutant/unit
mass of forest fuel consumed)
- 8.5 kg/Mg (17 Ib/ton) for total particulate
- 70 kg/Mg (140 Ib/ton) for carbon monoxide
- 12 kg/Mg (24 Ib/ton) for total hydrocarbon (as Cfy)
- 2 kg/Mg (4 Ib/ton) for nitrogen oxides (NOX)
- Negligible for sulfur oxides (SOX)
L - Fuel loading consumed (mass of forest fuel/unit land
area burned)
A - Land area burned
EI - Total emissions of pollutant "i" (mass pollutant)
For example, suppose that is is necessary to estimate the total particu-
late emissions from a 10,000 hectare wildfire in the Southern area (Region 8).
From Table 11.1-1, it is seen that the average fuel loading is 20 megagrams per
hectare (9 tons per acre). Further, the pollutant yield for particulates is
8.5 kilograms per megagram (17 Ib/ton). Therefore, the emissions are:
11.1-4 EMISSION FACTORS 9/88
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9/88
Miscellaneous Sources
11.1-5
-------
E - (8.5 kg/Mg of fuel) (20 Mg of fuel hectare) (10,000 hectares)
E - 1.700,000 kg - 1,700 Mg
The most effective method of controlling wildfire emissions is, of course,
to prevent the occurrence of wildfires, by various means at the land manager's
disposal. A frequently used technique for reducing wildfire occurrence is
"prescribed" or "hazard reduction" burning. This type of managed burn involves
combustion of litter and underbrush to prevent fuel buildup under controlled
conditions, thus reducing the danger'of a wildfire. Although some air pollution
is generated by this preventive burning, the net amount is believed to be a
relatively smaller quantity than that produced by wildfires.
11.1.3 Prescribed Burning1
Prescribed burning is a land treatment, used under controlled conditions,
to accomplish natural resource management objectives. It is one of several
land treatments, used individually or in combination, including chemical and
mechanical methods. Prescribed fires are conducted within the limits of a fire
plan and prescription which describes both the acceptable range of weather,
moisture, fuel and fire behavior parameters and the ignition method to achieve
the desired effects. Prescribed fire is a cost effective and ecologically
sound tool for forest, range and wetland management. Its use reduces the
potential for destructive wildfires and thus maintains long term air quality.
Also, the practice removes logging residues, controls insects and disease,
improves wildlife habitat and forage production, increases water yield, main-
tains natural succession of plant communities, and reduces the need for pes-
ticides and herbicides. The major air pollutant concern is the smoke produced.
Smoke from prescribed fires is a complex mixture of carbon, tars, liquids
and different gases. This open combustion source produces particles of widely
ranging size, depending to some extent on the rate of energy release of the
fire. For example, total particulate and particulate less than 2.5 micrometers
mean mass cutpoint diameter are produced in different proportions, depending on
rates of heat release by the fire.2 This difference is greatest for the highest
intensity fires, and particle volume distribution is bimodal, with peaks near
0.3 micrometers and exceeding 10 micrometers.^ Particles over about 10 microns,
probably of ash and partially burned plant matter, are extrained by the turbu-
lent nature of high intensity fires.
Burning methods differ with fire objectives and with fuel and weather
conditions. For example, the various ignition techniques used to burn under
standing trees include 1) heading fire, a line of fire that runs with the wind;
2) backing fire, a line of fire that moves into the wind; 3) spot fires, which
burn from a number of fires ignited along a line or in a pattern; and 4) flank
fire, a line of fire that is lit into the wind, to spread laterally to the
direction of the wind. Methods of igniting the fires depend on forest manage-
ment objectives and the size of the area. Often, on areas of 50 or more acres,
helicopters with aerial ignition devices are used to light broadcast burns.
Broadcast fires may involve many lines of fire in a pattern that allows the
strips of fire to burn together over a sizeable area.
11.1-6 EMISSION FACTORS 9/88
-------
In discussing prescribed burning, the combustion process is divided into
preheating, flaming, glowing and smoldering phases. The different phases of
combustion greatly affect the amount of emissions produced.5~7 The preheating
phase seldom releases significant quantities of material to the atmosphere.
Glowing combustion is usually associated with burning of large concentrations
of woody fuels such as logging residue piles. The smoldering combustion phase
is a very inefficient and incomplete combustion process that emits pollutants
at a much higher ratio to the quantity of fuel consumed than does the flaming
combustion of similar materials.
o _Q
The amount of fuel consumed depends on the moisture content of the fuel.0 *
For most fuel types, consumption during the smoldering phase is much greatest
when the fuel is driest. When lower layers of the fuel are moist, the fire
usually is extinguished rapidly.10
The major pollutants from wildland burning are particulate, carbon monoxide
and volatile organics. Nitrogen oxides are emitted at rates of from 1 to 4
grams per kilogram burned, depending on combustion temperatures. Emissions of
sulfur oxides are negligible. 1-12
Particulate emissions depend on the mix of combustion phase, the rate of
energy release, and the type of fuel consumed. All of these elements must be
considered in selecting the appropriate emission factor for a given fire and
fuel situation. In some cases, models developed by the U. S. Forest Service
have been used to predict particulate emission factors and source strength.1-'
These models address fire behavior, fuel chemistry, and ignition technique, and
they predict the mix of combustion products. There is insufficient knowledge
at this time to describe the effect of fuel chemistry on emissions.
Table 11.1-3 presents emission factors from various pollutants, by fire
and fuel configuration. Table 11.1-4 gives emission factors for prescribed
burning, by geographical area within the United States. Estimates of the
percent of total fuel consumed by region were compiled by polling experts
from the Forest Service. The emission factors are averages and can vary by
as much as 50 percent with fuel and fire conditions. To use these factors,
multiply the mass of fuel consumed per hectare by the emission factor for the
appropriate fuel type. The mass of fuel consumed by a fire is defined as the
available fuel. Local forestry officials often compile information on fuel
consumption for prescribed fires and have techniques for estimating fuel
consumption under local conditions. The Southern Forestry Smoke Management
Guidebook-* and the Prescribed Fire Smoke Management Guide1-* should be consulted
when using these emission factors.
The regional emission factors in Table 11.1-4 should be used only for
general planning purposes. Regional averages are based on estimates of the
acreage and vegetation type burned and may not reflect prescribed burning
activities In a given state. Also, the regions identified are broadly defined,
and the mix of vegetation and acres burned within a given state may vary
considerably from the regional averages provided. Table 11.1-4 should not be
used to develop emission inventories and control strategies.
To develop state emission inventories, the user is strongly urged to con-
tact that state's federal land management agencies and state forestry agencies
that conduct prescribed burning to obtain the best Information on such activities.
9/88 Miscellaneous Sources 11.1-7
-------
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11.1-8
EMISSION FACTORS
9/88
-------
TABLE 11.1-4.
EMISSION FACTORS FOR PRESCRIBED BURNING
BY U. S. REGION
Regional
configuration and
fuel type8
Pacific Northwest
Logging slash
Filed slash
Douglas fir/
Western hemlock
Mixed conifer
Ponder os a pine
Hardwood
Underburning pine
Average for region
Pacific Southwest
Sagebrush
Chaparral
Pi nyon/ Juniper
Underburing pine
Grassland
Average for region
Southeast
Palmetto/ gallberry
Underburning pine
Logging slash
Grassland
Other
Average for region
Rocky Mountain
Logging slash
Underburning pine
Grassland
Other
Average for region
North Central and Eastern
Logging slash
Grassland
Underburning pine
Other
Average for region
Percent
of fuelb
42
24
19
6
4
5
100
35
20
20
15
10
100
35
30
20
'10
5
100
50
20
20
10
100
50
30
10
10
100
Pollutant0
Particulate
(*/kg)
PM2.5
4
12
12
13
11
30
9.4
8
PM10
5
13
13
13
12
30
10.3
9
9
13
30
10
13.0
15
30
13
10
17
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4
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10
17
11.9
13
10
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17
14
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6
17
17
20
18
35
13.3
15
15
17
35
10
17.8
16
35
20
10
17
21.9
6
35
10
17
13.7
17
10
35
17
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37
175
175
126
112
163
111.1
62
62
175
163
75
101.0
125
163
126
75
175
134
37
163
75
175
83.4
175
75
163
175
143.8
aRegional areas are generalized, e. g., the Pacific Northwest includes
Oregon, Washington and parts of Idaho and California. Fuel types
generally reflect the ecosystems of a region, but users should seek
advice on fuel type mix for a given season of the year. An average
factor for Northern California could be more accurately described as
chaparral, 25Z; underburning pine, 15Z; sagebrush, 15%; grassland,
5%; mixed conifer, 25Z; and Douglas fir/Western hemlock, 15%.
Dash * no data.
bBased on the Judgment of forestry experts.
cAdapted from Table 11.1-3 for the dominant fuel types burned.
9/88
Miscellaneous Sources
11.1-9
-------
References for Section 11.1
1. Development Of Emission Factors For Estimating Atmospheric Emissions From
Forest Fires. EPA-450/3-73-009, U. S. Environmental Protection Agency,
Research Triangle Park, NC, October 1973.
2. D. E. Ward and C. C. Hardy, Advances In The Characterization And Control
Of Emissions From Prescribed Broadcast Fires Of Coniferous Species Logging
Slash On Clearcut Units. EPA DW12930110-01-3/DOE DE-A179-83BP12869, U. S.
Forest Service, Seattle, WA, January 1986.
3. L. F. Radke, et al., Airborne Monitoring And Smoke Characterization Of
Prescribed Fires On Forest Lands In Western Washington and Oregon,
EPA-600/X-83-047, U. S. Environmental Protection Agency, Cincinnati, OH,
July 1983.
4. H. E. Mobley, et al., A Guide For Prescribed Fire In Southern Forests,
U. S. Forest Service, Atlanta, GA, 1973.
5. Southern Forestry Smoke Management Guidebook, SE-10, U. S. Forest Service,
Asheville, NC, 1976.
6. D. E. Ward and C. C. Hardy, "Advances In The Characterization And Control
Of Emissions From Prescribed Fires", Presented at the 77th Annual Meeting
of the Air Pollution Control Association, San Francisco, CA, June 1984.
7. C. C. Hardy and D. E. Ward, "Emission Factors For Particulate Matter By
Phase Of Combustion From Prescribed Burning", Presented at the Annual
Meeting of the Air Pollution Control Association Pacific Northwest
International Section, Eugene, OR, November 19-21, 1986.
8. D. V. Sandberg and R. D. Ottmar, "Slash Burning And Fuel Consumption In
The Douglas Fir Subregion", Presented at the 7th Conference On Fire And
Forest Meteorology, Fort Collins, CO, April 1983.
9. D. V. Sandberg, "Progress In Reducing Emissions From Prescribed Forest
Burning In Western Washington And Western Oregon", Presented at the Annual
Meeting of the Air Pollution Control Association Pacific Northwest
International Section, Eugene, OR, November 19-21, 1986.
10. R. D. Ottmar and D. V. Sandberg, "Estimating 1000-hour Fuel Moistures In
The Douglas Fir Subregion", Presented at the 7th Conference On Fire And
Forest Meteorology, Fort Collins, CO, April 25-28, 1983.
11. D. V. Sandberg, et al.. Effects Of Fire On Air - A State Of Knowledge
Review. WO-9, U. S. Forest Service, Washington, DC, 1978. •
12. C. K. McMahon, "Characteristics Of Forest Fuels, Fires, And Emissions",
Presented at the 76th Annual Meeting of the Air Pollution Control
Association, Atlanta, GA, June 1983.
13. D. E. Ward, "Source Strength Modeling Of Particulate Matter Emissions From
Forest Fires", Presented at the 76th Annual Meeting of the Air Pollution
Control Association, Atlanta, GA, June 1983.
11.1-10 EMISSION FACTORS 9/88
-------
14. D. E. Ward, et al., "Particulate Source Strength Determination For Low-
intensity Prescribed Fires", Presented at the Agricultural Mr Pollutants
Specialty Conference, Air Pollution Control Association, Memphis, TN,
March 18-19, 1974.
15. Prescribed Fire Smoke Management Guide, 420-1, BIFC-BLM Warehouse, 3905
Vista Avenue, Boise, ID, February 1985.
9/88 Miscellaneous Sources 11.1-11
-------
11.2.1 UNPAVED ROADS
11.2.1.1 General
Dust plumes trailing behind vehicles traveling on unpaved roads are a
familiar sight in rural areas of the United States. When a vehicle travels an
unpaved road, the force of the wheels on the road surface causes pulverization
of surface material. Particles are lifted and dropped from the rolling wheels,
and the road surface is exposed to strong air currents in turbulent shear with
the surface. The turbulent wake behind the vehicle continues to act on the
road surface after the vehicle has passed.
11.2.1.2 Emissions Calculation And Correction Parameters
The quantity of dust emissions from a given segment of unpaved road varies
linearly with the volume of traffic. Also, field investigations have shown
that emissions depend on correction parameters (average vehicle speed, average
vehicle weight, average number of wheels per vehicle, road surface texture and
road surface moisture) that characterize the condition of a particular road and
the associated vehicle traffic.*"^
Dust emissions from unpaved roads have been found to vary in direct
proportion to the fraction of silt (particles smaller than 75 micrometers in
diameter) in the road surface materials. The silt fraction is determined by
measuring the proportion of loose dry surface dust that passes a 200 mesh
screen, using the ASTM-C-136 method. Table 11.2.1-1 summarizes measured silt
values for industrial and rural unpaved roads.
The silt content of a rural dirt road will vary with location, and it
should be measured. As a conservative approximation, the silt content of the
parent soil in the area can be used. However, tests show that road silt con-
tent is normally lower than in the surrounding parent soil, because the fines
are continually removed by the vehicle traffic, leaving a higher percentage
of coarse particles.
Unpaved roads have a hard, generally nonporous surface that usually dries
quickly after a rainfall. The temporary reduction in emissions caused by
precipitation may be accounted for by not considering emissions on "wet" days
(more than 0.254 millimeters [0.01 inches] of precipitation).
The following empirical expression may be used to estimate the quantity of
size specific particulate emissions from an unpaved road, per vehicle kilometer
traveled (VKT) or vehicle mile traveled (VMT), with a rating of A:
/s\ /S\ /W\0-7 /w\0-5 /365-p\
— ) (— ) (— ) H — (kg/vKT)
V2/ W \2-7/ w \365/
E = k(5.9) - ) ( — - ) - - (Ib/VMT)
V2/ \30/ W V/ \365/
9/88 Miscellaneous Sources 11.2.1-1
-------
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EMISSION FACTORS 9/88
-------
where: E = emission factor
k = particle size multiplier (dimensionless)
s = silt content of road surface material (%)
S - mean vehicle speed, km/hr (mph)
W = mean vehicle weight, Mg (ton)
w = mean number of wheels
p = number of days with at least 0.254 mm
(0.01 in.) of precipitation per year
The particle size multiplier, k, in the equation varies with aerodynamic particle
size range as follows:
Aerodynamic Particle Size Multiplier For Equation
<30 uma
1.0
OO urn
0.80
<15 urn
0.50
£10 urn
0.36
_<5um
0.20
_<2.5 urn
0.095
a Stokes diameter
The number of wet days per year, p, for the geographical area of interest
should be determined from local climatic data. Figure 11.2.1-1 gives the
geographical distribution of the mean annual number of wet days per year in the
United States.
The equation retains the assigned quality rating, if applied within the
ranges of source conditions that were tested in developing the equation, as
follows:
Ranges Of Source Conditions For Equation
Road silt
content
(wgt. %)
4.3 - 20
Mean vehicle weight
Mg
2.7 - 142
ton
3 - 157
Mean vehicle speed
km/hr
21 - 64
mph
13-40
mean no.
of wheels
4-13
Also, to retain the quality rating of the equation when addressing a specific
unpaved road, it is necessary that reliable correction parameter values be
determined for the road in question. The field and laboratory procedures for
determining road surface silt content are given in Reference 4. In the event
that site specific values for correction parameters cannot be.obtained, the
appropriate mean values from Table 11.2.1-1 may be used, but the quality rating
of the equation is reduced to B.
The equation was developed for calculating annual average emissions, and
thus, is to be multiplied by annual vehicle distance traveled (VDT). Annual
average values for each of the correction parameters are to be substituted for
the equation. Worst case emissions, corresponding to dry road conditions, may
be calculated by setting p » 0 in the equation (equivalent to dropping the last
9/88
Miscellaneous Sources
11.2.1-3
-------
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term from the equation). A separate set of nonclimatic correction parameters
and a higher than normal VDT value may also be justified for the worst case
average period (usually 24 hours). Similarly, in using the equation to calcu-
late emissions for a 91 day season of the year, replace the term (365-p)/365
with the term (91-p)/91, and set p equal to the number of wet days in the 91 day
period. Also, use appropriate seasonal values for the nonclimatic correction
parameters and for VDT.
11.2.1.3 Controls
Common control techniques for unpaved roads are paving, surface treating
with penetration chemicals, working into the roadbed of stabilization chemicals,
watering, and traffic control regulations. Chemical stabilizers work either by
binding the surface material or by enhancing moisture retention. Paving, as a
control technique, is often not economically practical. Surface chemical treat-
ment and watering can be accomplished with moderate to low costs, but frequent
retreatments are required. Traffic controls, such as speed limits and traffic
volume restrictions, provide moderate emission reductions but may be difficult
to enforce. The control efficiency obtained by speed reduction can be calcu-
lated using the predictive emission factor equation given above.
The control efficiencies achievable by paving can be estimated by comparing
emission factors for unpaved and paved road conditions, relative to airborne
particle size range of interest. The predictive emission factor equation for
paved roads, given in Section 11.2.6, requires estimation of the silt loading
on the traveled portion of the paved surface, which in turn depends on whether
the pavement is periodically cleaned. Unless curbing is to be installed, the
effects of vehicle excursion onto shoulders (berms) also must be taken into
account in estimating control efficiency.
The control efficiencies afforded by the periodic use of road stabilization
chemicals are much more difficult to estimate. The application parameters
which determine control efficiency include dilution ratio, application intensity
(mass of diluted chemical per road area) and application frequency. Other
factors that affect the performance of chemical stabilizers include vehicle
characteristics (e. g., traffic volume, average weight) and road characteristics
(e. g., bearing strength).
Besides water, petroleum resin products have historically been the dust
suppressants most widely used on industrial unpaved roads. Figure 11.2.1-2
presents a method to estimate average control efficiencies associated with
petroleum resins applied to unpaved roads. Several items should be noted:
1. The terra "ground inventory" represents the total volume (per
unit area) of petroleum resin concentrate (not solution)
applied since the start of the dust control season.
2. Because petroleum resin products must be periodically reapplied
to unpaved roads, the use of a time-averaged control efficiency
value is appropriate. Figure 11.2.1-2 presents control effi-
ciency values averaged over two common application intervals,
two weeks and one month. Other application intervals will
require interpolation.
9/88 Miscellaneous Sources 11.2.1-5
-------
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11.2.1-6
EMISSION FACTORS
9/88
-------
3. Note that zero efficiency is assigned until the ground inventory
reaches 0.2 liters per square meter (0.05 gallons per square yard).
As an example of the use of Figure 11.2.1-2, suppose that the equation has
been used to estimate an emission factor of 2.0 kilograms per vehicle kilometer
traveled for particles equal to or less than 10 microns from a particular road.
Also, suppose that, starting on May 1, the road is treated with 1 liter per
square meter of a (1 part petroleum resin to 5 parts water) solution on the
first of each month until October. Then, the following average controlled
emission factors are found:
Period
May
June
July
August
September
Ground
Inventory
(Win2)
0.17
0.33
0.50
0.67
0.83
Average Control
Efficiency3
(%)
0
62
68
74
80
Average Controlled
Emission Factor
(kg/VKT)
2.0
0.76
0.64
0.52
0.40
aFrom Figure 11.2.1-2, <_ 10 urn. Zero efficiency assigned if ground
inventory is less than 0.2 L/m2 (0.05 gal/yd2).
Newer dust suppressants have been successful in controlling emissions from
unpaved roads. Specific test results for those chemicals, as well as for petro-
leum resins, are provided in References 14 through 16.
References for Section 11.2.1
1. C. Cowherd, Jr., et al., Development Of Emission Factors For Fugitive Dust
Sources, EPA-450/3-74-037, U. S. Environmental Protection Agency, Research
Triangle Park, NC, June 1974.
2. R. J. Dyck and J. J. Stukel, "Fugitive Dust Emissions From Trucks On
Unpaved Roads", Environmental Science and Technology, 10(10);1046-1048,
October 1976.
3. R. 0. McCaldin and K. J. Heidel, "Particulate Emissions From Vehicle
Travel Over Unpaved Roads", Presented at the 71st Annual Meeting of the
Air Pollution Control Association, Houston, TX, June 1978.
4. C. Cowherd, Jr., et al., Iron And Steel Plant Open Dust Source Fugitive
Emission Evaluation, EPA-600/2-79-013, U. S. Environmental Protection
Agency, Cincinnati, OH, May 1979.
5. R. Bohn, et al., Fugitive Emissions From Integrated Iron And Steel Plants,
EPA-600/2-78-050, U. S. Environmental Protection Agency, Cincinnati, OH,
March 1978.
9/88 Miscellaneous Sources 11.2.1-7
-------
6. R. Bohn, Evaluation Of Open Dust Sources In The Vicinity Of Buffalo, New
York, EPA Contract No. 68-02-2545, Midwest Research Institute, Kansas
City, MO, March 1979.
7. C. Cowherd, Jr., and T. Cuscino, Jr., Fugitive Emissions Evaluation,
MRI-4343-L, Midwest Research Institute, Kansas City, MO, February 1977.
8. T. Cuscino, Jr., et al., Taconite Mining Fugitive Emissions Study,
Minnesota Pollution Control Agency, Roseville, MN, June 1979.
9. K. Axetell and C. Cowherd, Jr., Improved Emission Factors For Fugitive
Dust From Western Surface Coal Mining Sources, 2 Volumes, EPA Contract
No. 68-03-2924, PEI, Inc., Kansas City, MO, July 1981.
10. T. Cuscino, Jr., et al., Iron And Steel Plant Open Source Fugitive Emis-
sion Control Evaluation, EPA-600/2-83-110, U. S. Environmental Protection
Agency, Cincinnati, OH, October 1983.
11. J. Patrick Reider, Size Specific Emission Factors For Uncontrolled Indus-
trial and Rural Roads, EPA Contract No. 68-02-3158, Midwest Research
Institute, Kansas City, MO, September 1983.
12. C. Cowherd, Jr., and P. Englehart, Size Specific Particulate Emission
Factors For Industrial And Rural Roads, EPA-600/7-85-038, U. S. Environ-
mental Protection Agency, Cincinnati, OH, September 1985.
13. .Climatic Atlas Of The United States, U. S. Department Of Commerce,
Washington, DC, June 1968.
14. G. E. Muleski, et al., Extended Evaluation Of Unpaved Road Dust Suppres-
sants In The Iron And Steel Industry, EPA-600/2-84-027, U. S. Environmental
Protection Agency, Cincinnati, OH, February 1984.
15. C. Cowherd, Jr., and J. S. Kinsey, Identification, Assessment And Control
Of Fugitive Particulate Emissions, EPA-600/8-86-023, U. S. Environmental
Protection Agency, Cincinnati, OH, August 1986.
16. G. E. Muleski and C. Cowherd, Jr., Evaluation Of The Effectiveness Of
Chemical Dust Suppressants On Unpaved Roads, EPA-600/X-XX-XXX, U. S.
Environmental Protection Agency, Cincinnati, OH, November 1986.
11.2.1-8 EMISSION FACTORS 9/88
-------
11.2.3 AGGREGATE HANDLING AND STORAGE PILES
11.2.3.1 General
Inherent in operations that use minerals in aggregate form is the
maintenance of outdoor storage piles. Storage piles are usually left uncovered,
partially because of the need for frequent material transfer into or out of
storage.
Dust emissions occur at several points in the storage cycle, such as
during material loading onto the pile, disturbances by strong wind currents,
and loadout from the pile. The movement of trucks and loading equipment in the
storage pile area is also a substantial source of dust.
11.2.3.2 Emissions And Correction Parameters
The quantity of dust emissions from aggregate storage operations varies
with the volume of aggregate passing through the storage cycle. Also, emis-
sions depend on three parameters of the condition of a particular storage pile:
age of the pile, moisture content and proportion of aggregate fines.
When freshly processed aggregate is loaded onto a storage pile, its
potential for dust emissions is at a maximum. Fines are easily disaggregated
and released to the atmosphere upon exposure to air currents, either from aggre-
gate transfer itself or from high winds. As the aggregate weathers, however,
potential for dust emissions is greatly reduced. Moisture causes aggregation
and cementation of fines to the surfaces of larger particles. Any significant
rainfall soaks the interior of the pile, and the drying process is very slow.
Silt (particles equal to or less than 75 microns in diameter) content is
determined by measuring the portion of dry aggregate material that passes
through a 200 mesh screen, using ASTM-C-136 method. Table 11.2.3-1 summarizes
measured silt and moisture values for industrial aggregate materials.
11.2.3.3 Predictive Emission Factor Equations
Total dust emissions from aggregate storage piles are contributions of
several distinct source activities within the storage cycle:
1. Loading of aggregate onto storage piles (batch or continuous drop
operations).
2. Equipment traffic in storage area.
3. Wind erosion of pile surfaces and ground areas around piles.
4. Loadout of aggregate for shipment or for return to the process stream
(batch or continuous drop operations).
Adding aggregate material to a storage pile or removing it both usually
involve dropping the material onto a receiving surface. Truck dumping on the
pile or loading out from the pile to a truck with a front end loader are exam-
ples of batch drop operations. Adding material to the pile by a conveyor
stacker is an example of a continuous drop operation.
9/88 Miscellaneous Sources 11.2.3-1
-------
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11.2.3-2
EMISSION FACTORS
9/88
-------
The quantity of particulate emissions generated by either type of drop
operation, per ton of material transferred, may be estimated, with a rating of
A, using the following empirical expression2;
E = k(0.0016)
(kg/Mg)
E = k(0.0032)
(Ib/ton)
where: E * emission factor
k = particle size multiplier (dimensionless)
U * mean wind speed, m/s (mph)
M = material moisture content (%)
The particle size multiplier, k, varies with aerodynamic particle diameter, as
shown in Table 11.2.3-2.
TABLE 11.2.3-2. AERODYNAMIC PARTICLE SIZE MULTIPLIER (k)
<30 urn
0.74
<15 urn
0.48
<10 urn
0.35
<5 urn
0.20
<2.5 urn
0.11
The equation retains the assigned quality rating if applied within the
ranges of source conditions that were tested in developing the equation, as
given in Table 11.2.3-3. Note that silt content is included in Table 11.2.3-3,
even though silt content does not appear as a correction parameter in the equa-
tion. While it is reasonable to expect that silt content and emission factors
are interrelated, no significant correlation between the two was found during
the derivation of the equation, probably because most tests with high silt
contents were conducted under lower winds, and vice versa. It is recommended
that estimates from the equation be reduced one quality rating level, if the
silt content used in a particular application falls outside the range given in
Table 11.2.3-3.
9/88
Miscellaneous Sources
11.2.3-3
-------
TABLE 11.2.3-3. RANGES OF SOURCE CONDITIONS FOR EQUATION 1
Silt
Content
0.44 - 19
Moisture
Content
0.25 - 4.8
Wind Speed
(m/s) (mph)
0.6 - 6.7 1.3 - 15
Also, to retain the equation's quality rating when applied to a specific
facility, it is necessary that reliable correction parameters be determined for
the specific sources of interest. The field and laboratory procedures for
aggregate sampling are given in Reference 3. In the event that site specific
values for correction parameters cannot be obtained, the appropriate mean
values from Table 11.2.3-1 may be used, but, in that case, the quality rating
of the equation is reduced by one level.
For emissions from equipment traffic (trucks, front end loaders, dozers,
etc.) traveling between or on piles, it is recommended that the equations for
vehicle traffic on unpaved surfaces be used (see Section 11.2.1). For vehicle
travel between storage piles, the silt value(s) for the areas among the piles
(which may differ from the silt values for the stored materials) should be used.
Worst case emissions from storage pile areas occur under dry windy condi-
tions. Worst case emissions from materials handling operations may be calcu-
lated by substituting into the equation appropriate values for aggregate material
moisture content and for anticipated wind speeds during the worst case averaging
period, usually 24 hours. The treatment of dry conditions for vehicle traffic
(Section 11.2.1), centering on parameter p, follows the methodology described
in Section 11.2.1. Also, a separate set of nonelimatic correction parameters and
source extent values corresponding to higher than normal storage pile activity
may be justified for the worst case averaging period.
11.2.3.4 Controls
Watering and chemical wetting agents are the principal means for control
of aggregate storage pile emissions. Enclosure or covering of inactive piles
to reduce wind erosion can also reduce emissions. Watering is useful mainly to
reduce emissions from vehicle traffic in the storage pile area. Watering of
the storage piles themselves typically has only a very temporary slight effect
on total emissions. A much more effective technique is to apply chemical wet-
ting agents for better wetting of fines and longer retention of the moisture
film. Continuous chemical treatment of material loaded onto piles, coupled
with watering or treatment of roadways, can reduce total particulate emissions
from aggregate storage operations by up to 90 percent.9
References for Section 11.2.3
1. C. Cowherd, Jr., et al., Development Of Emission Factors For Fugitive Dust
Sources. EPA-450/3-74-037, U. S. Environmental Protection Agency, Research
Triangle Park, NC, June 1974.
11.2.3-4 EMISSION FACTORS 9/88
-------
2. R. Bohn, et al., Fugitive Emissions From Integrated Iron And Steel Plants,
EPA-600/2-78-050, U. S. Environmental Protection Agency, Cincinnati, OH,
March 1978.
3. C. Cowherd, Jr., et al., Iron And Steel Plant Open Dust Source Fugitive
Emission Evaluation. EPA-600/2-79-103, U. S. Environmental Protection
Agency, Cincinnati, OH, May 1979.
4. R. Bohn, Evaluation Of Openj>ust Sources In The Vicinity Of Buffalo.
New York. EPA Contract No. 68-02-2545, Midwest Research Institute, Kansas
City, MO, March 1979.
5. C. Cowherd, Jr., and T. Cuscino, Jr., Fugitive Emissions Evaluation,
MRI-4343-L, Midwest Research Institute, Kansas City, MO, February 1977.
6. T. Cuscino, et al., Taconite Mining Fugitive Emissions Study, Minnesota
Pollution Control Agency, Roseville, MN, June 1979.
7. K. Axetell and C. Cowherd, Jr., Improved Emission Factors For Fugitive
Dust From Western Surface Coal Mining Sources, 2 Volumes, EPA Contract
No. 68-03-2924, PEI, Inc., Kansas City, MO, July 1981.
8. E. T. Brookman, et al., Determination of Fugitive Coal Dust Emissions From
Rotary Railcar Dumping. 1956-L81-00, TRC, Hartford, CT, May 1984.
9. G. A. Jutze, et al.. Investigation Of Fugitive Dust Sources Emissions And
Control. EPA-450/3-74-036a, U. S. Environmental Protection Agency, Research
Triangle Park, NC, June 1974.
9/88 Miscellaneous Sources 11,2.3-5
-------
11.2.6 INDUSTRIAL PAVED ROADS
11.2.6.1 General
Various field studies have indicated that dust emissions from industrial
paved roads are a major component of atmospheric particulate matter in the
vicinity of industrial operations. Industrial traffic dust has been found to
consist primarily of mineral matter, mostly tracked or deposited onto the road-
way by vehicle traffic itself, when vehicles enter from an unpaved area or
travel on the shoulder of the road, or when material is spilled onto the paved
surface from open truck bodies.
11.2.6.2 Emissions And Correction Parameters'^
The quantity of dust emissions from a given segment of paved road varies
linearly with the volume of traffic. In addition, field investigations have
shown that emissions depend on correction parameters (road surface silt content,
surface dust loading and average vehicle weight) of a particular road and asso-
ciated vehicle traffic.
Dust emissions from industrial paved roads have been found to vary in
direct proportion to the fraction of silt (particles equal to or less than 75
microns in diameter) in the road surface material. The silt fraction is deter-
mined by measuring the proportion of loose dry surface dust that passes a 200
mesh screen, using the ASTM-C-136 method. In addition, it has also been found
that emissions vary in direct proportion to the surface dust loading. The road
surface dust loading is that loose material which can be collected by broom
sweeping and vacuuming of the traveled portion of the paved road. Table 11.2.6-1
summarizes measured silt and loading values for industrial paved roads.
11.2.6.3 Predictive Emission Factor Equations
The quantity of total suspended particulate emissions generated by vehicle
traffic on dry industrial paved roads, per vehicle kilometer traveled (VKT) or
vehicle mile traveled (VMT), may be estimated with a rating of B or D (see
below), using the following empirical expression^:
0.0221 ( ( ( /( 1 (kg/VKT) (1)
\280
L \ /W V>.7
0.0771 [ 1 ( ]( ] (Ib/VMT)
1000 M 3
where: E = emission factor
I = industrial augmentation factor (dimensionless) (see below)
n = number of traffic lanes
s = surface material silt content (%)
L = surface dust loading, kg/km (Ib/mile) (see below)
W = average vehicle weight, Mg (ton)
11/88 Miscellaneous Sources 11.2.6-1
-------
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11.2.6-2
EMISSION FACTORS
9/88
-------
The industrial road augmentation factor (I) in Equation 1 takes into account
higher emissions from industrial roads than from urban roads. I • 7.0 for a
paved industrial roadway which traffic '-enters from unpaved areas. 1-3.5 for
an industrial roadway with unpaved shoulders where 20 percent of the vehicles
are forced to travel temporarily with one set of wheels on the shoulder. I = 1.0
for cases in which traffic travels only on paved areas. A value between 1.0 and
7.0 which best represents conditions for paved roads at a certain industrial
facility should be used for I in the equation.
The equation retains the quality rating of B if applied to vehicles
traveling entirely on paved surfaces (I = 1.0) and if applied within the range
of source conditions that were tested in developing the equation as follows:
Silt
content
(%)
5.1-92
Surface loading
kg/km Ib/mile
42.0 - 2000 149 - 7100
No. of
lanes
2-4
Vehicle weight
Mg tons
2.7 - 12 3-13
If I is less than 1.0, the rating of the equation drops to D, because of the
subjectivity in the guidelines for estimating I.
The quantity of particle emissions in the finer size ranges generated by
traffic consisting predominately of medium and heavy duty vehicles on dry
industrial paved roads, per vehicle unit of travel, may be estimated, with a
rating of A, using the equation:
E - k(3.5)
0.3
(kg/VKT)
(Ib/VMT)
(2)
where: E - emission factor
sL = road surface silt loading, g/m^ (oz/yd^)
The particle size multiplier (k) above varies with aerodynamic size range
as follows:
Aerodynamic Particle Size
Multiplier (k) For Equation 2
(Dimensionless)
<15 urn
<10 urn
<2.5 urn
0.28
0.22
0.081
9/88
Miscellaneous Sources
11.2.6-3
-------
To determine particulate emissions for a specific particle size range, use the
appropriate value of k above.
The equation retains the quality rating of A, if applied within the range
of source conditions that were tested in developing the equation as follows:
silt loading, 2 - 240 g/m2 (0.06 - 7.1 oz/yd2)
mean vehicle weight, 6 - 42 Mg (7 - 46 tons)
The following single valued emission factors^ may be used in lieu of
Equation 2 to estimate particle emissions in the finer size ranges generated by
light duty vehicles on dry, heavily loaded industrial roads, with a rating of C:
Emission Factors For Light Duty
Vehicles On Heavily Loaded Roads
<15 urn
<10 urn
0.12 kg/VKT
(0.41 Ib/VMT)
0.093 kg/VKT
(0.33 Ib/VMT)
These emission factors retain the assigned quality rating, if applied within
the range of source conditions that were tested in developing the factors, as
follows:
silt loading, 15 - 400 g/m2 (0.44 - 12 oz/yd2)
mean vehicle weight, ^4 Mg (^4 tons)
Also, to retain the quality ratings of Equations 1 and 2 when applied to
a specific industrial paved road, it is necessary that reliable correction
parameter values for the specific road in question be determined. The field
and laboratory procedures for determining surface material silt content and
surface dust loading are given in Reference 2. In the event that site specific
values for correction parameters cannot be obtained, the appropriate mean values
from Table 11.2.6-1 may be used, but the quality ratings of the equation should
be reduced by one level.
11.2.6.4 Controls
Common control techniques for industrial paved roads are broom sweeping,
vacuum sweeping and water flushing, used alone or in combination. All of these
techniques work by reducing the silt loading on the traveled portions of the
road. As indicated by a comparison of Equations 1 and 2, fine particle emis-
sions are less sensitive to the value of silt loading than are total suspend
particulate emissions. Consistent with this, control techniques are generally
less effective for the finer particle sizes.* The exception is water flushing,
which appears preferentially to remove (or agglomerate) fine particles from the
paved road surface. Broom sweeping is generally regarded as the least effec-
tive of the common control techniques, because the mechanical sweeping process
is inefficient in removing silt from the road surface.
11.2.6-4
EMISSION FACTORS
9/88
-------
Although there are relatively few quantitative data on emissions from
controlled paved roads, those that are available indicate that adequate esti-
mates generally may be obtained by substituting controlled loading values into
Equations 1 and 2. The major exception to this is water flushing combined
with broom sweeping. In that case, the equations tend to overestimate emis-
sions substantially (by an average factor of 4 or more).
On a paved road with moderate traffic (500 vehicles per day), to achieve
control efficiencies on the order of 50 percent, requires cleaning of the
surface at least twice per week.4 This is because of the characteristically
rapid buildup of road surface material from spillage and the tracking and depo-
sition of material from adjacent unpaved surfaces, including the shoulders
(berms) of the paved road. Because industrial paved roads usually do not have
curbs, it is important that the width of the paved road surface be sufficient
for vehicles to pass without excursion onto unpaved shoulders. Equation 1
indicates that eliminating vehicle travel on unpaved or untreated shoulders
would effect a major reduction in particulate emissions. An even greater
effect, by a factor of 7, would result from preventing travel from unpaved
roads or parking lots onto the paved road of interest.
References for Section 11.2.6
1. R. Bohn, et al«, Fugitive Emissions From Integrated Oron And Steel Plants,
EPA-600/2-78-050, U. S. Environmental Protection Agency, Cincinnati, OH,
March 1978.
2. C. Cowherd, Jr., et al., Iron And Steel Plant Open Dust Source Fugitive
Emission Evaluation, EPA-600/2-79-103, U. S. Environmental Protection
Agency, Cincinnati, OH, May 1979.
3. R. Bohn, Evaluation Of Open Dust Sources In The Vicinity Of Buffalo,
New York, EPA Contract No. 68-02-2545, Midwest Research Institute, Kansas
City, MO, March, 1979.
4. T. Cuscino, Jr., et al., Iron And Steel Plant Open Source Fugitive Emission
Control Evaluation, EPA-600/2-83-110, U. S. Environmental Protection Agency,
Cincinnati, OH, October 1983.
5. J. Patrick Reider, Size Specific Particulate Emission Factors For Uncon-
trolled Industrial And Rural Roads. EPA Contract No. 68-02-3158, Midwest
Research Institute, Kansas City, MO, September 1983.
6. C. Cowherd, Jr., and P. Englehart, Size Specific Particulate Emission
Factors For Industrial And Rural Roads. EPA-600/7-85-038, U. S. Environ-
mental Protection Agency, Cincinnati, OH, September 1985.
9/88 Miscellaneous Sources 11.2.6-5
-------
-------
11.2.7 INDUSTRIAL WIND EROSION
11.2.7.1 General1'3
Dust emissions may be generated by wind erosion of open aggregate storage
piles and exposed areas within an industrial facility. These sources typically
are characterized by nonhomogeneous surfaces impregnated with nonerodible ele-
ments (particles larger than approximately 1 cm in diameter). Field testing of
coal piles and other exposed materials using a portable wind tunnel has shown
that (a) threshold wind speeds exceed 5 m/s (11 mph) at 15 cm above the surface
or 10 m/s (22 mph) at 7 m above the surface, and (b) particulate emission rates
tend to decay rapidly (half life of a few minutes) during an erosion event. In
other words, these aggregate material surfaces are characterized by finite
availability of erodible material (mass/area) referred to as the erosion
potential. Any natural crusting of the surface binds the erodible material,
thereby reducing the erosion potential.
11.2.7.2 Emissions And Correction Parameters
If typical values for threshold wind speed at 15 cm are corrected to
typical wind sensor height (7-10 m), the resulting values exceed the upper
extremes of hourly mean wind speeds observed in most areas of the country. In
other words, mean atmospheric wind speeds are not sufficient to sustain wind
erosion from flat surfaces of the type tested. However, wind gusts may quickly
deplete a substantial portion of the erosion potential. Because erosion poten-
tial has been found to increase rapidly with increasing wind speed, estimated
emissions should be related to the gusts of highest magnitude.
The routinely measured meteorological variable which best reflects the
magnitude of wind gusts is the fastest mile* This quantity represents the wind
speed corresponding to the whole mile of wind movement which has passed by the
1 mile contact anemometer in the least amount of time. Daily measurements of
the fastest mile are presented in the monthly Local Climatological Data (LCD)
summaries. The duration of the fastest mile *-typically about 2 min (for a
fastest mile of 30 mph), matches well with the half life of the erosion
process, which ranges between 1 and 4 min. It should be noted, however, that
peak winds can significantly exceed the daily fastest mile.
The wind speed profile in the surface boundary layer is found to follow a
logarithmic distribution:
u(z) = vr*_ In z_ (z > z0) (1)
0.4 z0
where u = wind speed, cm/sec
u* * friction velocity, cm/sec
z • height above test surface, cm
zo * roughness height, cm
0.4 « von Karman's constant, dimensionless
The friction velocity (u*) is a measure of wind shear stress on the erodible
surface, as determined from the slope of the logarithmic velocity profile. The
roughness height (zo) is a measure of the roughness of the exposed surface as
determined from the y intercept of the velocity profile, i.e., the height at
9/88 Miscellaneous Sources '$1.2.7-1
-------
which the wind speed is zero. These parameters are illustrated in Figure
11.2.7-1 for a roughness height of 0.1 cm.
Emissions generated by wind erosion are also dependent on the frequency of
disturbance of the erodible surface because each time that a surface is dis-
turbed, its erosion potential is restored. A disturbance is defined as an
action which results in the exposure of fresh surface material. On a storage
pile, this would occur whenever aggregate material is either added to or
removed from the old surface. A disturbance of an exposed area may also result
from the turning of surface material to a depth exceeding the size of the
largest pieces of material present.
11.2.7.3 Predictive Emission Factor Equation*
The emission factor for wind generated particulate emissions from mixtures
of erodible and nonerodible surface material subject to disturbance may be
expressed in units of g/nr-yr as follows:
Emission factor - k P (2)
i - 1
where k » particle size multiplier
N » number of disturbances per year
Pi = erosion potential corresponding to the observed (or probable)
fastest mile of wind for the ith period between disturbances,
g/m2
The particle size multiplier (k) for Equation 2 varies with aerodynamic
particle size, as follows:
AERODYNAMIC PARTICLE SIZE MULTIPLIERS FOR EQUATION 2
<30 urn <15 um <10 urn <2.5 urn
1.0 0.6 0.5 0.2
This distribution of particle size within the OOurn fraction is comparable
to the distributions reported for other fugitive dust sources where wind speed
is a factor. This is illustrated, for example, in the distributions for batch
and continuous drop operations encompassing a number of test aggregate materials
(see Section 11.2.3).
In calculating emission factors, each area of an erodible surface that is sub-
ject to a different frequency of disturbance should be treated separately. For
a surface disturbed daily, N - 365/yr, and for a surface disturbance once
every 6 months, N - 2/yr.
Equations 2 and 3 apply only to dry, exposed materials with limited erosion
potential. The resulting calculation is valid only for a time period as long
or longer than the period between disturbances. Calculated emissions repre-
sent intermittent events and should not be input directly into dispersion
models that assume steady state emission rates.
11.2.7-2 EMISSION FACTORS 9/88
-------
9/88
Figure 11.2.7-1. Illustration of logarithmic velocity profile.
Miscellaneous Sources 11.2.7-3
-------
The erosion potential function for a dry, exposed surface is:
P - 58 (u* - u*)2 25 (u* - u*)
P - 0 for u* < u*
~~ t
(3)
where u* - friction velocity (m/s)
ut - threshold friction velocity (m/s)
Because of the nonlinear form of the erosion potential function, each erosion
event must be treated separately.
For unc rusted surfaces, the threshold friction velocity is best estimated from
the dry aggregate structure of the soil. A simple hand sieving test of surface
soil (adapted from a laboratory procedure published by W. S. Che pi 1) can be
used to determine the mode of the surface aggregate size distribution by
inspection of relative sieve catch amounts, following the procedure described
below. Alternatively, the threshold friction velocity for erosion can be
determined from the mode of the aggregate size distribution, as described by
Gillette.5"6
Threshold friction velocities for several surface types have been determined
by field measurements with a portable wind tunnel. These values are presented
in Table 11.2.7-1.
TABLE 11.2.7-1. FIELD PROCEDURE FOR DETERMINTION OF THRESHOLD
FRICTION VELOCITY
Tyler
sieve no.
5
9
16
32
60
Opening
(mm)
4
2
1
0.5
0.25
Midpoint
(mm)
3
1.5
0.75
0.375
u* (cm/sec)
t
100
72
58
43
FIELD PROCEDURE FOR DETERMINATION OF THRESHOLD FRICTION VELOCITY
(from a 1952 laboratory procedure published by W. S. Chepil)
1. Prepare a nest of sieves with the following openings: 4 mm, 2 mm, 1 mm,
0.5 mm, 0.25 mm. Place a collector pan below thi crhtirj • f taga *5M36
2. Collect a sample representing the surface layer of loose particles
(approximately 1 cm in depth, for an encrusted surface), removing any rocks
11.2.7-4
EMISSION FACTORS
9/88
-------
larger than about 1 cm in average physical diameter. The area to be
sampled should be not less than 30 cm.
3. Pour the sample into the top sieve (4 mm opening), and place a lid on the
top.
4. Move the covered sieve/pan unit by hand, using a broad circular arm motion
in the horizontal plane. Complete 20 circular movements at a speed just
necessary to achieve some relative horizontal motion between the sieve and
the particles.
5. Inspect the relative quantities of catch within each sieve, and determine
where the mode in the aggregate size distribution lies, i. e., between the
opening size of the sieve with the largest catch and the opening size of
the next largest sieve.
6. Determine the threshold friction velocity from Figure 1.
The fastest mile of wind for the periods between disturbances may be obtained
from the monthly LCD summaries for the nearest reporting weather station that
is representative of the site in question. ' These summaries report actual
fastest mile values for each day of a given month. Because the erosion
potential is a highly nonlinear function of the fastest mile, mean values of
the fastest mile are inappropriate. The anemometer heights of reporting
weather stations are found in Reference 8, and should be corrected to a 10 m
reference height using Equation 1.
TABLE 11.2.7-2. THRESHOLD FRICTION VELOCITIES
Material
Overburden3
Scoria (roadbed
material)3
Ground coala
(surrounding coal
pile)
Uncrusted coal pilea
Scraper tracks on
coal pilea»b
Fine coal dust on
concrete padc
a Western surface coal
b Lightly crusted.
c Eastern power plant.
Threshold
friction
velocity
(m/s)
1.02
1.33
0.55
1.12
0.62
0.54
mine.
Roughness
height
(cm)
0.3
0.3
0.01
0.3
0.06
0.2
Threshold
velocity at 10
z0 - Actual z0
21
27
16
23
15
11
wind
m (m/s)
- 0.5 cm
19
25
10
21
12
10
Ref.
2
2
2
2
2
3
9/88
Miscellaneous Sources
11.2.7-5
-------
To convert Che fastest mile of wind (u+) from a reference anemometer height of
10 m to the equivalent friction velocity (u*)» the logarithmic wind speed
profile may be used to yield the following equation:
u* - 0.053 u+10 (4)
where u* - friction velocity (m/s)
u iQ ™ fastest mile of reference anemometer for period between
disturbances (m/s)
This assumes a typical roughness height of 0.5 cm for open terrain.
Equation 4 is restricted to large relatively flat piles or exposed areas with
little penetration into the surface wind layer.
If the pile significantly penetrates the surface wind layer (i.e., with a
height-to-base ratio exceeding 0.2), it is necessary to divide the pile area
into subareas representing different degrees of exposure to wind. The results
of physical modeling show that the frontal face of an elevated pile is exposed
to wind speeds of the same order as the approach wind speed at the top of the
pile.
For two representative pile shapes (conical and oval with flattop, 37 degree
side slope), the ratios of surface wind speed (ug) to approach wind speed (ur)
have been derived from wind tunnel studies. ^ The results are shown in
Figure 11.2.7-2 corresponding to an actual pile height of 11 m, a reference
(upwind) anemometer height of 10 m, and a pile surface roughness height (zo)
of 0.5 cm. The measured surface winds correspond to a height of 25 cm above
the surface. The area fraction within each contour pair is specified in
Table 11.2.7-3.
The profiles of us/ur in Figure 11.2.7-2 can be used to estimate the surface
friction velocity distribution around similarly shaped piles, using the
following procedure:
1. Correct the fastest mile value (u"*") for the period of interest from the
anemometer height (z) to a reference height of 10 m (u ^Q) using a
variation of Equation 1:
u+1Q = u+ In (10/0.005) (5)
In (z/0.005) •
where a typical roughness height of 0.5 cm (0.005 m) has been assumed.
If, a site specific roughness height is available, it should be used.
f
2. Use the appropriate part of Figure 11.2.7-2 based on the pile shape and
orientation to the fastest mile of wind, to obtain the corresponding sur-
face wind speed distribution (u+ ):
s
(6)
ur
11.2.7-6 EMISSION FACTORS 9/88
-------
Flow
Direction
Pile A
Pile B1
Pile B2
Pile B3
Figure 11.2.7-2. Contours of Normalized Surface Wind Speeds, Ug/ur
9/88
Miscellaneous Sources
11.2.7-7
-------
3. For any subarea of the pile surface having a narrow range of surface wind
speed, use a variation of Equation 1 to calculate the equivalent friction
velocity (u*):
0.4 u+
u* - - 0.10 u+
25_
1*0.5
From this point on, the procedure is identical to that used for a flat pile,
as described above.
Implementation of the above procedure is carried out in the following steps:
1. Determine threshold friction velocity for erodible material of interest
(see Table 11.2.7-2 or determine from mode of aggregate size
distribution).
2. Divide the exposed surface area into subareas of constant frequency of
disturbance (N).
TABLE 11.2.7-2. SUBAREA DISTRIBUTION FOR REGIMES OF us/ur
Percent of pile surface area (Figure
Pile subarea
0.2a
0.2b
0.2c
0.6a
0.6b
0.9
1.1
Pile A
5
35
-
48
-
12
~*
Pile Bl
5
2
29
26
24
14
—
Pile B2
3
28
-
29
22
15
3
11.2.7-2)
Pile B3
3
25
-
28
26
14
4
3. Tabulate fastest mile values (u+) for each frequency of disturbance and
correct them to 10 m (U+IQ) using Equation 5.
4. Convert fastest mile values (U+JQ) to equivalent friction velocities (u*),
taking into account (a) the uniform wind exposure of nonelevated surfaces,
using Equation 4, or (b) the nonuniform wind exposure of elevated surfaces
(piles), using Equations 6 and 7.
5. For elevated surfaces (piles), subdivide areas of constant N into sub-
areas of constant u* (i.e., within the isopleth values of us/ur in Figure
11.2.7-2 and Table 11.2.7-3) and determine the size of each subarea.
6. Treating each subarea (of constant N and u*) as a separate source,
calculate the erosion potential (P^) for each period between disturbances
using Equation 3 and the emission factor using Equation 2.
11.2.7-8 EMISSION FACTORS 9/88
-------
7. Multiply the resulting emission factor for each subarea by the size of
the subarea, and add the emission contributions of all subareas. Note
that the highest 24-hr emissions would be expected to occur on the
windiest day of the year. Maximum emissions are calculated assuming a
single event with the highest fastest mile value for the annual period.
The recommended emission factor equation presented above assumes that all of
the erosion potential corresponding to the fastest mile of wind is lost during
the period between disturbances. Because the fastest mile event typically
lasts only about 2 min, which corresponds roughly to the halflife for the
decay of actual erosion potential, it could be argued that the emission factor
overestimates particulate emissions. However, there are other aspects of the
wind erosion process which offset this apparent conservatism:
1. The fastest mile event contains peak winds which substantially exceed the
mean value for the event.
2. Whenever the fastest mile event occurs, there are usually a number of
periods of slightly lower mean wind speed which contain peak gusts of the
same order as the fastest mile wind speed.
Of greater concern is the likelihood of overprediction of wind erosion
emissions in the case of surfaces disturbed infrequently in comparison to the
rate of crust formation.
11.2.7.4 Example calculation for wind erosion emissions from conically shaped
coal pile
A coal burning facility maintains a conically shaped surge pile 11 m in height
and 29.2 m in base diameter, containing about 2000 Mg of coal, with a bulk
density of 800 kg/m3 (50 lb/ft3). The total exposed surface area of the pile
is calculated as follows:
S - r r2 + h2
- 3.14(14.6) (14.6)2 + (11.O)2
- 838 m2
Coal is added to the pile by means of a fixed stacker and reclaimed by front-
end loaders operating at the base of the pile on the downwind side. In addi-
tion, every 3 days 250 Mg (12.5% of the stored capacity of coal) is added back
to the pile by a topping off operation, thereby restoring the full capacity of
the pile. It is assumed that (a) the reclaiming operation disturbs only a
limited portion of the surface area where the daily activity is occurring,
such that the remainder of the pile surface remains intact, and (b) the top-
ping off operation creates a fresh surface on the entire pile while restoring
its original shape in the area depleted by daily reclaiming activity.
Because of the high frequency of disturbance of the pile, a large number of
calculations must be made to determine each contribution to the total annual
wind erosion emissions. This illustration will use a single month as an
example.
9/88 Miscellaneous Sources 11.2.7-9
-------
Prevailing
Wind
Direction
Circled values
refer to us/ur
* A portion of 03 is disturbed daily by reclaiming activities.
ttrea
ID
A
B
Cl + C2
us
Ur
0.9
0.6
0.2
%
12
48
40
Area (m^)
101
402
335
838
Figure 11.2.7-3. Example 1: Pile surface areas within each wind speed regime.
11.2.7-10
EMISSION FACTORS
9/88
-------
Step 1: In the absence of field data for estimating the threshold friction
velocity, a value of 1.12 m/s is obtained from Table 11.2.7-2.
Step 2: Except for a small area near the base of the pile (see
Figure 11.2.7-3), the entire pile surface is disturbed every 3 days, corre-
sponding to a value of N - 120/yr. It will be shown that the contribution of
the area where daily activity occurs is negligible so that it does not need to
be treated separately in the calculations.
Step 3; The calculation procedure involves determination of the fastest mile
for each period of disturbance. Figure 11.2.7-4 shows, a representative set of
values (for a 1 month period) that are assumed to be applicable to the geographic
area of the pile location. The values have been separated into 3 day periods,
and the highest value in each period is indicated. In this example, the
anemometer height is 7 m, so that a height correction to 10 m is needed for the
fastest mile values. From Equation 5,
In (10/0.005)
u+y In (7.0.005)
1.05 u+7
Step 4: The next step is to convert the fastest mile value for each 3 day
period into the equivalent friction velocities for each surface wind regime
(i. e., us/ur ratio) of the pile, using Equations 6 and 7. Figure 11.2.7-3
shows the surface wind speed pattern (expressed as a fraction of the approach
wind speed at a height of 10 m). The surface areas lying within each wind
speed regime are tabulated below the figure.
The calculated friction velocities are presented in Table 11.2.7-4. As
indicated, only three of the periods contain a friction velocity which exceeds
the threshold value of 1.12 m/s for an uncrusted coal pile. These three values
all occur within the Ug/Uj. - 0.9 regime of the pile surface.
Step 5: This step is not necessary because there is only one frequency of
disturbance used in the calculations. It is clear that the small area of
daily disturbance (which lies entirely within the Ug/ur "0.2 regime) is never
subject to wind speeds exceeding the threshold value.
9/88 Miscellaneous Sources 11.2.7-11
-------
Local Climatological Data
MONTHLY SUMMARY
WIND
e
o
a
S
UJ
1
30
01
10
13
12
20
29
29
22
1 4
29
17
21
10
10
01
33
27
32
24
22
32
29
07
34
31
30
30
33
34
29
a
2s
(/< Ul
S
14
5.3
10.5
2.4
1 l .0
1 1 .3
1 1 . 1
19.6
10.9
3.0
14.6
22.3
7.9
7.7
4.5
6.7
3.7
1 .2
4.3
9.3
7.5
0.3
7.1
2.4
5.9
1 .3
2. 1
8.3
8.2
5.0
3. 1
4.9
o
Ul
k»J
a
AVCRACC
M.P M
15
6.9
10.6
6.0
M.4
1 1 .9
19.0
19.8
1 l .2
8.1
15.1
23.3
3.5
5.5
9.6
8.8
3.8
1 .5
5.8
0.2
7.8
0.6
7.3
8.5
8.8
1 .7
2.2
8.5
8.3
6.6
5.2
5.5
FASTEST
MILE
o'
CL r
VI
16
10
16
1 7
15
5.3
yj
2?
18
rf
©
15
12
| J
©
16
5g
T"4
1 5
H3
16
16
y
Ttf
9
8
X
O
o
w
CL
O
17
36
01
02
13
l l
30
30
30
13
12
29
17
18
13
1 l
36
34
31
35
24
20
32
13
02
32
32
26
32
32
31
25
FOR THE MONTH:
30
—
3.3
•^••••ta «
1 . 1
(
31
29
1UTE: 1 1
UJ
a
22
i
2
3
4
5
6
7
e
9
10
1 1
12
13
I 4
5
16
17
18
19
20
21
22
23
24
25
26
27
25
29
30
31
Figure 11.2.7-4. Daily fastest miles of wind for periods of interest.
11.2.7-12
EMISSION FACTORS
9/88
-------
TABLE 11.2.7-4. EXAMPLE 1: CALCULATION OF FRICTION VELOCITIES
u+y u+io
3 Day
period
1
2
3
4
5
6
7
8
9
10
(mph)
14
29
30
31
22
21
16
25
17
13
(m/s)
6.3
13.0
13.4
13.9
9.8
9.4
7.2
11.2
7.6
5.8
(mph)
15
31
32
33
23
22
17
26
18
14
(m/s) US/UT
6.6
13.7
14.1
14.6
10.3
9.9
7.6
11.8
8.0
6.1
u* -
0.2
0.13
0.27
0.28
0.29
0.21
0.20
0.15
0.24
0.16
0.12
0.1 u+8
0.6
0.40
0.82
0.84
0.88
0.62
0.59
0.46
0.71
0.48
0.37
(m/s)
0.9
0.59
1.23
1.27
1.31
0.93
0.89
0.68
1.06
0.72
0.55
Steps 6 and 7: The final set of calculations (shown in Table 11.2.7-5)
involves the tabulation and summation of emissions for each disturbance period
and for the affected subarea. The erosion potential (P) is calculated from
Equation 3.
TABLE 11.2.7-5. EXAMPLE 1: CALCULATION OF PM1Q EMISSIONS8
3 Day
period u* (m/s)
u* - u*c (m/s) P (g/m2) ID
Pile Surface
Area kPA
2
3
4
1.23
1.27
1.31
0.11
0.15
0.19
3.45
5.06
6.84
A
A
A
Total PMj
101
101
101
0 emissions
170
260
350
- 780
"where u*t - 1.12 m/s for uncrusted coal and k - 0.5 for
For example, the calculation for the second 3 day period is:
P2 - 58(1.23 - 1.12)2 + 25(1.23 - 1.12)
- 0.70 + 2.75 - 3.45 g/m2
The PMio emissions generated by each event are found as the product of the
PMio multiplier (k - 0.5), the erosion potential (P), and the affected area
of the pile (A).
9/88
Miscellaneous Sources
11.2.7-13
-------
As shown in Table 11.2.7-5, the results of these calculations indicate a
monthly PM^o emission total of 780 g.
11.2.7.5 Example calculation for wind erosion from flat area covered with coal
dust
A flat circular area of 29.2 m in diameter is covered with coal dust left over
from the total reclaiming of a conical coal pile described in the example
above. The total exposed surface area is calculated as follows:
d2 = 0.785 (29. 2)2 = 670 m2
This area will remain exposed for a period of 1 month when a new pile will be
formed.
Step 1: In the absence of field data for estimating the threshold friction
velocity, a value of 0.54 m/s is obtained from Table 11.2.7-2.
Step 2: The entire surface area is exposed for a period of 1 month after
removal of a pile and N = 1/yr.
Step 3: From Figure 11.2.7-5, the highest value of fastest mile for the
30 day period (31 mph) occurs on the llth day of the period. In this example,
the reference anemometer height is 7 m, so that a height correction is needed
for the fastest mile value. From Step 3 of the previous example, U+IQ = 1.05
u+y, so that u+io = 33 mph.
Step 4: Equation 4 is used to convert the fastest mile value of 33 mph
(14.6 m/s) to an equivalent friction velocity of 0.77 m/s. This value exceeds
the threshold friction velocity from Step 1 so that erosion does occur.
Step 5: This step is not necessary because there is only one frequency of
disturbance for the entire source area.
Steps 6 and 7: The PM^Q emissions generated by the erosion event are
calculated as the product of the PM^o multiplier (k = 0.5), the erosion
potential (P) and the source area (A). The erosion potential is calculated
from Equation 3 as follows:
P = 58(0.77 - 0.54)2 + 25(0.77 - 0.54)
= 3.07 + 5.75
= 8.82 g/m2
Thus the PMjQ emissions for the 1 month period are found to be:
E = (0.5)(8.82 g/m2)(670 m2)
= 3.0 kg
11.2.7-14 EMISSION FACTORS 9/88
-------
References for Section 11.2.7
1. C. Cowherd Jr., "A New Approach to Estimating Wind Generated Emissions
from Coal Storage Piles", Presented at the APCA Specialty Conference on
Fugitive Dust Issues in the Coal Use Cycle, Pittsburgh, PA, April 1983.
2. K. Axtell and C. Cowherd, Jr., Improved Emission Factors for Fugitive Dust
from Surface Coal Mining Sources, EA-600/7-84-048, U. S. Environmental
Protection Agency, Cincinnati, OH, March 1984.
3. G. E. Muleski, "Coal Yard Wind Erosion Measurement", Midwest Research
Institute, Kansas City, MO, March 1985.
4. Update of Fugitive Dust Emissions Factors in AP-42 Section 11.2 - Wind
Erosion. MRl No. 8985-K, Midwest Research Institute, Kansas City, MO, 1988.
5. W. S. Chepil, "Improved Rotary Sieve for Measuring State and Stability
of Dry Soil Structure", Soil Science Society of America Proceedings,
J£:113-117, 1952.
6. D. A. Gillette, et al., "Threshold Velocities for Input of Soil
Particles Into the Air By Desert Soils", Journal of Geophysical Research,
_85_(C10): 5621-5630.
7. Local Climatological Data, National Climatic Center, Asheville, NC.
8. M. J. Changery, National Wind Data Index Final Report. HCO/T1041-01 UC-60,
National Climatic Center, Asheville, NC, December 1978.
9. B. J. B. Stunder and S. P. S. Arya, "Windbreak Effectiveness for Storage
Pile Fugitive Dust Control: A Wind Tunnel Study", Journal of the Air
Pollution Control Association. 38:135-143, 1988.
9/88 Miscellaneous Sources 11.2.7-15
-------
APPENDIX C.3
SILT ANALYSIS PROCEDURES
1. Select the appropriate 8 inch diameter 2 inch deep sieve sizes.
Recommended standard series sizes are 3/8 inch No. 4, No. 20, No. 40,
No. 100, No. 140, No. 200, and a pan. .The No. 20 and the No. 200 are
mandatory. Comparable Tyler Series sizes can also be used.
2. Obtain a mechanical sieving device such as a vibratory shaker or a
Roto-Tap (without the tapping function).
3. Clean the sieves with compressed air and/or a soft brush. Material lodged
in the sieve openings or adhering to the sides of the sieve should be
removed without handling the screen roughly, if possible.
4. Obtain a scale with capacity of at least 1600 grams, and record its make,
capacity, smallest increment, date of last calibration, and accuracy.
5. Record the tare weight of sieves and pan, and check the zero before every
.weighing.
6. After nesting the sieves in decreasing order of hole size, and with the
pan at the bottom, dump dried laboratory sample into the top sieve,
preferably immediately after moisture analysis. The sample should weigh
between 800 and 1600 grams (1.8 and 3.5 pounds). Brush fine material
adhering to the sides of the container into the top sieve, and cover the
top sieve with a special lid normally purchased with the pan.
7. Place nested sieves into the mechanical device, and sieve for 10 minutes.
Remove pan containing minus No. 200 and weigh its contents. Repeat the
sieving in 10 minute intervals until the difference between two successive
pan sample weights is less than 3.0 percent when the tare of the pan has
been substracted. Do not sieve longer than 40 minutes.
8. Weigh each sieve and its contents, and record the weight. Remember to
check the zero before every weighing.
9. Collect the laboratory sample, and place it in a separate container if
further analysis is expected.
10. Calculate the percent of mass less than the 200 mesh screen (75 micro-
meters). This is the silt content.
0. S. OmtaVBir HOOTING CFTTCZ 1988/526-090/87005
9/88 Appendix C.3 C.3-1
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