-------
Table 1.1-16. EMISSION FACTOR EQUATIONS FOR TRACE ELEMENTS FROM COAL
COMBUSTION"
EMISSION FACTOR EQUATION RATING: Ab
Pollutant
Emission Equation
(lb/1012 Btu)c
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Cobalt
Lead
Manganese
Nickel
0.92 * (C/A * PM)063
3.1*(C/A*PM)085
1.2*(C/A*PM)U
3.3*(C/A*PM)05
3.7*(C/A*PM)058
1.7 * (C/A * PM)(
3.4 * (C/A * PM)1
3.8 * (C/A * PM)1
4.4 * (C/A * PM)1
,069
,080
,060
,048
a Reference 55. The equations were developed from emissions data from bituminous coal combustion,
subbituminous coal combustion, and from lignite combustion. The equations may be used to generate
factors for both controlled and uncontrolled boilers. The emission factor equations are applicable to all
typical firing configurations for electric generation (utility), industrial, and commercial/industrial
boilers firing bituminous coal, subbituminous coal, and lignite. Thus, all SCCs for these boilers are
assigned to the factors.
b AP-42 criteria for rating emission factors were used to rate the equations.
c The factors produced by the equations should be applied to heat input. To convert from lb/1012 Btu to
kg/joules, multiply by 4.31 x 10'16.
C = concentration of metal in the coal, parts per million by weight (ppmwt).
A = weight fraction of ash in the coal. For example, 10% ash is 0.1 ash fraction.
PM = Site-specific emission factor for total paniculate matter, lb/106 Btu.
9/98
External Combustion Sources
1.1-37
-------
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§9i §iS gS c 11 ^^i'g&'SN-
lis lis fs IH -s -siiH='i§§
.HiO .2 CO S" XCJ uo uiO 4) -j3 !>„-_..
S3 o ^ «5 M)CN O04 U00 "^04 tCor^u'"'lO i O •> c O *^ O *i^ O W O 4) t O <^-- w rt c/3 t/3
"3C— *3a-i >"i SS a-i <^C-i ,3'^ SCHM
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1.1-38
EMISSION FACTORS
9/98
-------
Table 1.1-18 EMISSION FACTORS FOR TRACE METALS FROM
CONTROLLED COAL COMBUSTION3
Pollutant
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Chromium (VI)
Cobalt
Lead
Magnesium
Manganese
Mercury
Nickel
Selenium
Emission Factor (lb/ton)b
1.8E-05
4.1E-04
2.1E-05
5.1E-05
2.6E-04
7.9E-05
l.OE-04
4.2E-04
1.1E-02
4.9E-04
8.3E-05
2.8E-04
1.3E-03
EMISSION FACTOR RATING
A
A
A
A
A
D
A
A
A
A
A
A
A
References 35-53,62-70. The emission factors were developed from emissions data at eleven facilities
firing bituminous coal, fifteen facilities firing subbituminous coal, and from two facilities firing lignite.
The factors apply to boilers utilizing either venturi scrubbers, spray dryer absorbers, or wet limestone
scrubbers with an electrostatic precipitator (ESP) or Fabric Filter (FF). In addition, the factors apply
to boilers using only an ESP, FF, or venturi scrubber. SCCs = pulverized coal-fired, dry bottom
boilers, 1-01-002-02/22, 1-02-002-02/22, 1-03-002-06/22; pulverized coal, dry bottom,
tangentially-fired boilers, 1-01-002-12/26, 1-02-002-12/26, 1-03-002-16/26; cyclone boilers,
1-01-002-03/23, 1-02-002-03/23, 1-03-002-03/23; and, atmospheric fluidized bed combustors,
circulating bed, 1-01-002-18/38, 1-02-002-18, and 1-03-002-18.
Emission factor should be applied to coal feed, as fired. To convert from Ib/ton to kg/Mg, multiply by
0.5.
9/98
External Combustion Sources
1.1-39
-------
8
oo
D
O
S5
H
KH
pq
on
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1.1-40
EMISSION FACTORS
9/98
-------
O
ON
b
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CS CN CS
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CS CN (N
§99
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1 1 1
t
s
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-
u
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d
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d
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d
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9/98
External Combustion Sources
1.1-41
-------
Table 1.1-20. DEFAULT CO2 EMISSION FACTORS FOR U. S. COALS"
EMISSION FACTOR RATING: C
Coal Type
Subbituminous
High-volatile bituminous
Medium-volatile bituminous
Low-volatile bituminous
Average %Cb
66.3
75.9
83.2
86.1
Conversion Factor0
72.6
72.6
72.6
72.6
Emission Factor'1
(Ib/ton coal)
4810
5510
6040
6250
a This table should be used only when an ultimate analysis is not available. If the ultimate analysis is
available, CO2 emissions should be calculated by multiplying the %carbon (%C) by 72.6 This resultant
factor would receive a quality rating of "B".
b An average of the values given in References 2,76-77. Each of these references listed average carbon
contents for each coal type (dry basis) based on extensive sampling of U.S. coals.
c Based on the following equation:
44 ton CO,
12 ton C
- x 0.99 x 2000
Ib CO2
ton CO,
1
100%
= 72.6
Ib CO2
ton %C
Where:
44 = molecular weight of CO2,
12 = molecular weight of carbon, and
0.99 = fraction of fuel oxidized during combustion (Reference 16).
d To convert from Ib/ton to kg/Mg, multiply by 0.5.
1.1-42
EMISSION FACTORS
9/98
-------
2.0A
1.8A
S !'6A
It L4A
o is
;s« i-2A
"1 l.OA
II 0.8A
ft ^*
§* 0.6A
p
0.4A
0.2A
0
Scrubber
ESP
Baghouse
Uncontrolled
Multiple cyclone
i i i i i t t I i
l.OA
°-6A
0.4A
0.2A
^
1
3
_M
g. °
2 00
0.1 A I
0.06A * |
0.04A| §
11
0.02A.1 8
ta
0.01A —'
.1 .2 .4 .6 1 2 46 10
Particle diameter (lum)
20
40 60 100
0.1A
0.06A
0.04A
0.02A
0.01A
2
=
S
0.006A
0.004A
0.002A
0.001 A
Figure 1.1-1. Cumulative size-specific emission factors for an example dry bottom boiler
burning pulverized bituminous coal.
3.5A
S -
l!
'S a 2.1 A
0.70A
ESP
Multiple cyclone
l.OA
0.9A
0.8A
0.7A
0.6A
0.5A
0.4A
0.3A
0.2A
0.1A
-8
-I
.2
.6 1
0
4 6 10 20 40 60 100
0.1A
0.06A
0.04A |
•2-
0.02A .2 1
M en
*H
0.01A ^ 1"
^ o
0.006A if
0.004A S*
W
0.002A
0.001 A
Particle diameter ( m)
Figure 1.1-2. Cumulative size-specific emission factors for an example wet bottom boiler burning
pulverized bituminous coal.
9/98
External Combustion Sources
1.1-43
-------
t
w
l
l.OA
0.9A
0.8A
0.7A
0.6A
0.5A
0.4A
0.3A
0.2A
0.1A
0
ESPv
Uncontrolled
0.1 OA
0.06A
0.04A
0.02A
0.01A
0.006A
0.004A
0.002A
o
II
.1 .2 .4 .6 1 2 46 10
Particle diameter (jum)
20
40 60
0.001 A
100
•o
8
W
I
t/5
Figure 1.1-3. Cumulative size-specific emission factors for an example cyclone furnace
burning bituminous coal.
g a
<*-
-3
« g
•g °
~: M
C3 w)
r
10
9
8
7
6
5
4
3
2
1
0
.1
Multiple cyclone wilh-
flyash reinfection
Multiple cyclone without
flyash reinjection
Baghouse
Uncontrolled
•ESP
10.0
6.0
4.0
2.0
1.0
0.6
0.4
0.2
0.1
.4 .6 1 2 4 6 10 20
Particle diameter ( m)
40 60 100
00 t>
W W)
•o >
o
"o
0.10
0.06 u
0.04 |
0.02 |'
» 13
0-01 |^
0.006 | |
0.004 o g>
0.002
0.001
Figure 1.1-4. Cumulative size-specific emission factors for an example spreader stoker burning
bituminous coal.
1.1-44
EMISSION FACTORS
9/98
-------
g
7.2
S 6.4
^^ «
c 2 5-6
2 *«
.§ a 4-8
| 1 4-0
I | 3.2
5 6b
I* 2.4
J= 1.6
0.8
0
.1
Multiple
cyclone
10
6.0
4.0
2.0
0.2
0.1
.2
.61 2 4 6 10
Particle diameter ( m)
20
40 60 100
•a«
4) w
o ^*
§ 8
O M)
1.0 .2
0.6 jj
0.4
l-i
« B]
cn
1
Figure 1.1-5. Cumulative size-specific emission factors for an example overfeed stoker burning
bituminous coal.
1
.2 «
CA us
.S2 «
S — -
§ §
IS,
r
10
9
8
7
6
5
4
3
2
1
0
.1
UncontrollecK
.2
.61 2 4 6 10
Particle diameter ( m)
20
40 60 100
Figure 1.1-6. Cumulative size-specific emission factors for an example underfeed stoker
burning bituminous coal.
9/98
External Combustion Sources
1.1-45
-------
References For Section 1.1
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Inc., 1991, p. 239.
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1.1-46 EMISSION FACTORS 9/98
-------
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9/98 External Combustion Sources 1.1-47
-------
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1.1 -48 EMISSION FACTORS 9/98
-------
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9/98 External Combustion Sources 1.1 -49
-------
60. R. Meij, Auteru dr., The Fate Of Trace Elements At Coal-Fired Plants, Report No. 2561-MOC
92-3641, Rapport te bestellen bij; bibliotheek N.V. KEMA, February 13, 1992.
61. Locating And Estimating Air Emissions From Sources Of Manganese, EPA-450/4-84-007h,
September 1985.
62. Results of the September 10 and 11,1991 Mercury Removal Tests on the Units 1 & 2, and Unit 3
Scrubber Systems at the NSP Sherco Plant in Becker, Minnesota. Interpoll Laboratories, Inc.,
Circle Pines, Minnesota. October 30, 1991.
63. Results of the November 5, 1991 Air Toxic Emission Study on the No. 1, 3 & 4 Boilers at the
NSP Black Dog Plant. Interpoll Laboratories, Inc., Circle Pines, Minnesota. January 3, 1992.
64. Results of the January 1992 Air Toxic Emission Study on the No. 2 Boiler at the NSP Black Dog
Plant. Interpoll Laboratories, Inc., Circle Pines, Minnesota. May 4, 1992.
65. Results of the May 29, 1990 Trace Metal Characterization Study on Units 1 and 2 at the
Sherburne County Generating Station in Becker, Minnesota. Interpoll Laboratories, Inc., Circle
Pines, Minnesota. July, 1990.
66. Results of the May 1, 1990 Trace Metal Characterization Study on Units 1 and 2 at the
Sherburne County Generating Station. Interpoll Laboratories, Inc., Circle Pines, Minnesota.
July 18, 1990.
67. Results of the March 1990 Trace Metal Characterization Study on Unit 3 at the Sherburne
County Generating Station. Interpoll Laboratories, Circle Pines, Minnesota. June 7, 1990.
68. Field Chemical Emissions Monitoring Project: Site 19 Emissions Monitoring. Radian
Corporation, Austin, Texas. April, 1993. (EPRI Report)
69. Field Chemical Emissions Monitoring Project: Site 20 Emissions Monitoring. Radian
Corporation, Austin, Texas. March, 1994. (EPRI Report)
70. Characterizing Toxic Emissions from a Coal-Fired Power Plant Demonstrating the AFGDICCT
Project and a Plant Utilizing a Dry Scrubber /Baghhouse System. Final Draft Report.
Springerville Generating Station Unit No. 2. Southern Research Insititute, Birmingham,
Alabama. December, 1993.
71. Emissions Of Reactive Volatile Organic Compounds From Utility Boilers,
EPA-600/7-80-111, U. S. Environmental Protection Agency, Washington, DC,
May 1980.
72. EPA/IFP European Workshop On The Emission Of Nitrous Oxide For Fuel Combustion , EPA
Contract No. 68-02-4701, Ruiel-Malmaison, France, June 1-2, 1988.
73. R. Clayton, et al., NO^ Field Study, EPA-600/2-89-006, U. S. Environmental Protection Agency,
Research Triangle Park, NC, February 1989.
74. L. E. Amand, and S. Anderson, "Emissions of Nitrous Oxide from Fluidized Bed Boilers",
Presented at the Tenth International Conference on Fluidized Bed Combustor, San Francisco,
CA, 1989.
1.1-50 EMISSION FACTORS 9/98
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75. Alternative Control Techniques Document—NO x Emissions From Utility Boilers,
EPA-453/R-94-023, Office of Air Quality Standards, Research Triangle Park, NC, 1994.
76. Alliance Technologies Corporation, Evaluation of Significant Anthropogenic Sources of
Radiatively Important Trace Gases, U. S. Environmental Protection Agency, Office of Research
and Development, Research Triangle Park, NC, 1990.
77. R. A. Winschel, Richard, "The Relationship of Carbon Dioxide Emissions with Coal Rank and
Sulfur Content," Journal of the Air and Waste Management Association, Vol. 40, no. 6, pp. 861-
865, June 1990.
78. Public Service Electric and Gas Company Mercer Generating Station Unit No. 2 Emission
Compliance Test Program. November 1994.
79. Particulate Emission Study Performed for Madison Gas and Electric Company at the Blount
Street Station Units 7, 8, 9 Inlets/Outlets. Mostardi-Platt Associates, Inc. December 6, 1994.
80. Particulate Emission Study Performed for Marshfield Electric and Water Department at the
Wildwood Station Marshfield Wisconsin Boiler 5 Stack. Mostardi-Platt Associates, Inc.
January 23-25, 1990.
81. Report on Particulate, SO2, and NOX Compliance Testing. Dairy land Power Cooperative J.P.
Madgett Stack. Alma, Wisconsin. CAE. January 6, 1995.
82. Particulate Emissions Test Results. Portland General Electric Coal-fired Power Plant.
Boardman, Oregon. SAIC, Inc. January 25, 1994.
83. Report on Compliance Testing Performed at Marshfield Electric and Water Department
Wildwood Station Unit 5, Marshfield, Wisconsin. Clean Air Engineering, December 11, 1989.
84. Portland General Electric Company Boardman Coal Plant. Unit #1 Coal-fired Boiler.
Boardman, Oregon. August 24-27,1995.
85. Particulate Emission Compliance Study Performed for Portland General Electric at the Boardman
Plant Unit 1 Stack. Boardman, Oregon. September 19, 1996.
86. Emissions Source Test Report. Portland General Electric Coal-Fired Power Plant. Boardman,
Oregon. OMNI Environmental Services, Inc. October 17, 1990.
87. Source Emissions Test Report Compliance. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services. January 29, 1991.
88. Source Test Report. Particulate Emissions. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. January 14, 1991.
89. Emissions Source Test Rpeort. Portland General Electric Coal-Fired Power Plant. Boardman,
Oregon. OMNI Environmental Services, Inc. April 3, 1991.
90. Source Emissions Test Report. Portland General Electric Coal-Fired Power Plant. Boardman,
Oregon. OMNI Environmental Services, Inc. January 21, 1992.
9/98 External Combustion Sources 1.1-51
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91. Particulate Emissions Test Results. Portland General Electric Coal-fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. April 4, 1992.
92. Particulate Emissions Test Results. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. September 9, 1992.
93. Particulate Emissions Test Results. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. November 6,1992.
94. Particulate Emissions Test Results. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. January 26, 1993.
95. Stationary Source Sampling Report. Keystone Cogeneration Facility. Keystone Cogeneration
Facility. Logan Township, NJ. November 1994.
96. Source Emissions Survey of City Public Service Board J.K. Spruce Unit Number 1 Stack.
METCO Environmental. December 1992.
97. Report of Particulate Emission Testing on the Number 1 Boiler at Associated Milk Products
Incorporated Located in Jim Falls, Wisconsin. Environmental Services of American, Inc.
November 1994.
98. Appletone Papers, Inc. Boiler Emission Test at Appleton, WI. May 11 and 12, 1993. Badger
Laboratories and Engineering.
99. Appleton Papers, Inc. Boiler Emission Test Report at Appleton, WI. Badger Laboratories and
Engineering. October 11, 1993.
100. Results of a Source Emission Compliance Test on Boiler #2 at the Hills Farm Heating Plant,
Madison, Wisconsin. MMT Environmental Services, Inc. January 22, 1993.
101. Results of a Source Emission Compliance Test on Boiler #2 at the Hills Farm Heating Plant,
Madison, Wisconsin. MMT Environmental Services, Inc. March 2, 1995.
102. Report to Mosinee Paper Company for Particulate Matter Emission Testing. No. 6 Boiler at
Mosinee, Wisconsin. May 18, 19, and 20, 1993.
103. Report to Milwaukee County for Particulate Matter Emission Test Boiler No. 21. Environmental
Technology and Engineering Corporation. Novembers, 1991.
104. Report on Compliance Testing Conducted at Oscar Mayer Foods Corporation, Madison,
Wisconsin. Clean Air Engineering. July 21,1989.
1.1-52 EMISSION FACTORS 9/98
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13 Fuel Oil Combustion
1.3.1 General1'3
Two major categories of fuel oil are burned by combustion sources: distillate oils and residual oils.
These oils are further distinguished by grade numbers, with Nos. 1 and 2 being distillate oils; Nos. 5 and 6
being residual oils; and No. 4 being either distillate oil or a mixture of distillate and residual oils. No. 6
fuel oil is sometimes referred to as Bunker C. Distillate oils are more volatile and less viscous than residual
oils. They have negligible nitrogen and ash contents and usually contain less than 0.3 percent sulfur (by
weight). Distillate oils are used mainly in domestic and small commercial applications, and include
kerosene and diesel fuels. Being more viscous and less volatile than distillate oils, the heavier residual oils
(Nos. 5 and 6) may need to be heated for ease of handling and to facilitate proper atomization. Because
residual oils are produced from the residue remaining after the lighter fractions (gasoline, kerosene, and
distillate oils) have been removed from the crude oil, they contain significant quantities of ash, nitrogen,
and sulfur. Residual oils are used mainly in utility, industrial, and large commercial applications.
1.3.2 Firing Practices4
The major boiler configurations for fuel oil-fired combustors are watertube, firetube, cast iron, and
tubeless design. Boilers are classified according to design and orientation of heat transfer surfaces, burner
configuration, and size. These factors can all strongly influence emissions as well as the potential for
controlling emissions.
Watertube boilers are used in a variety of applications ranging from supplying large amounts of
process steam to providing space heat for industrial facilities. In a watertube boiler, combustion heat is
transferred to water flowing through tubes which line the furnace walls and boiler passes. The tube
surfaces in the furnace (which houses the burner flame) absorb heat primarily by radiation from the flames.
The tube surfaces in the boiler passes (adjacent to the primary furnace) absorb heat primarily by convective
heat transfer.
Firetube boilers are used primarily for heating systems, industrial process steam generators, and
portable power boilers. In firetube boilers, the hot combustion gases flow through the tubes while the
water being heated circulates outside of the tubes. At high pressures and when subjected to large variations
in steam demand, firetube units are more susceptible to structural failure than watertube boilers. This is
because the high-pressure steam in firetube units is contained by the boiler walls rather than by multiple
small-diameter watertubes, which are inherently stronger. As a consequence, firetube boilers are typically
small and are used primarily where boiler loads are relatively constant. Nearly all firetube boilers are sold
as packaged units because of their relatively small size.
A cast iron boiler is one in which combustion gases rise through a vertical heat exchanger and out
through an exhaust duct. Water in the heat exchanger tubes is heated as it moves upward through the
tubes. Cast iron boilers produce low pressure steam or hot water, and generally burn oil or natural gas.
They are used primarily in the residential and commercial sectors.
Another type of heat transfer configuration used on smaller boilers is the tubeless design. This
design incorporates nested pressure vessels with water in between the shells. Combustion gases are fired
into the inner pressure vessel and are then sometimes recirculated outside the second vessel.
9/98 External Combustion Sources 1.3-1
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1.3.3 Emissions5
Emissions from fuel oil combustion depend on the grade and composition of the fuel, the type and
size of the boiler, the firing and loading practices used, and the level of equipment maintenance. Because
the combustion characteristics of distillate and residual oils are different, their combustion can produce
significantly different emissions. In general, the baseline emissions of criteria and noncriteria pollutants are
those from uncontrolled combustion sources. Uncontrolled sources are those without add-on air pollution
control (APC) equipment or other combustion modifications designed for emission control. Baseline
emissions for sulfur dioxide (SO2) and particulate matter (PM) can also be obtained from measurements
taken upstream of APC equipment.
1.3.3.1 Particulate Matter Emissions6"15 -
Particulate emissions may be categorized as either filterable or condensable. Filterable emissions
are generally considered to be the particules that are trapped by the glass fiber filter in the front half of a
Reference Method 5 or Method 17 sampling van. Vapors and particles less than 0.3 microns pass through
the filter. Condensable particulate matter is material that is emitted in the vapor state which later
condenses to form homogeneous and/or heterogeneous aerosol particles. The condensable particulate
emitted from boilers fueled on coal or oil is primarily inorganic in nature.
Filterable particulate matter emissions depend predominantly on the grade of fuel fired.
Combustion of lighter distillate oils results in significantly lower PM formation than does combustion of
heavier residual oils. Among residual oils, firing of No. 4 or No. 5 oil usually produces less PM than does
the firing of heavier No. 6 oil.
In general, filterable PM emissions depend on the completeness of combustion as well as on the oil
ash content. The PM emitted by distillate oil-fired boilers primarily comprises carbonaceous particles
resulting from incomplete combustion of oil and is not correlated to the ash or sulfur content of the oil.
However, PM emissions from residual oil burning are related to the oil sulfur content. This is because low-
sulfur No. 6 oil, either from naturally low-sulfur crude oil or desulfurized by one of several processes,
exhibits substantially lower viscosity and reduced asphaltene, ash, and sulfur contents, which results in
better atomization and more complete combustion.
Boiler load can also affect filterable particulate emissions in units firing No. 6 oil. At low load
(50 percent of maximum rating) conditions, particulate emissions from utility boilers may be lowered by 30
to 40 percent and by as much as 60 percent from small industrial and commercial units. However, no
significant particulate emission reductions have been noted at low loads from boilers firing any of the
lighter grades. At very low load conditions (approximately 30 percent of maximum rating), proper
combustion conditions may be difficult to maintain and particulate emissions may increase significantly.
1.3.3.2 Sulfur Oxides Emissions1-2-6-9-16 -
Sulfur oxides (SOJ emissions are generated during oil combustion from the oxidation of sulfur
contained in the fuel. The emissions of SOX from conventional combustion systems are predominantly in
the form of SO2. Uncontrolled SOX emissions are almost entirely dependent on the sulfur content of the fuel
and are not affected by boiler size, burner design, or grade of fuel being fired. On average, more than 95
percent of the fuel sulfur is converted to SO2, about 1 to 5 percent is further oxidized to sulfur trioxide
(SO3), and 1 to 3 percent is emitted as sulfate particulate. SO3 readily reacts with water vapor (both in the
atmosphere and in flue gases) to form a sulfuric acid mist.
1.3-2 EMISSION FACTORS 9/98
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1.3.3.3 Nitrogen Oxides Emissions1'2'6-10'15'17-27 -
Oxides of nitrogen (NOX) formed in combustion processes are due either to thermal fixation of
atmospheric nitrogen in the combustion air (''thermal NOX"), or to the conversion of chemically bound
nitrogen in the fuel ("fuel NOX"). The term NOX refers to the composite of nitric oxide (NO) and nitrogen
dioxide (NO2). Test data have shown that for most external fossil fuel combustion systems, over 95
percent of the emitted NOX is in the form of nitric oxide (NO). Nitrous oxide (N2O) is not included in NOX
but has recently received increased interest because of atmospheric effects.
Experimental measurements of thermal NOX formation have shown that NOX concentration is
exponentially dependent on temperature, and proportional to N2 concentration in the flame, the square root
of O2 concentration in the flame, and the residence time. Thus, the formation of thermal NOX is affected by
four factors: (1) peak temperature, (2) fuel nitrogen concentration, (3) oxygen concentration, and (4) time
of exposure at peak temperature. The emission trends due to changes in these factors are generally
consistent for all types of boilers: an increase in flame temperature, oxygen availability, and/or residence
time at high temperatures leads to an increase in NOX production.
Fuel nitrogen conversion is the more important NOx-forming mechanism in residual oil boilers. It
can account for 50 percent of the total NOX emissions from residual oil firing. The percent conversion of
fuel nitrogen to NOX varies greatly, however; typically from 20 to 90 percent of nitrogen in oil is converted
to NOX. Except in certain large units having unusually high peak flame temperatures, or in units firing a
low nitrogen content residual oil, fuel NOX generally accounts for over 50 percent of the total NOX
generated. Thermal fixation, on the other hand, is the dominant NOx-forming mechanism in units firing
distillate oils, primarily because of the negligible nitrogen content in these lighter oils. Because distillate
oil-fired boilers are usually smaller and have lower heat release rates, the quantity of thermal NOX formed
in them is less than that of larger units which typically bum residual oil.28
A number of variables influence how much NOX is formed by these two mechanisms. One
important variable is firing configuration. NOX emissions from tangentially (corner) fired boilers are, on
the average, less than those of horizontally opposed units. Also important are the firing practices employed
during boiler operation. Low excess air (LEA) firing, flue gas recirculation (FGR), staged combustion
(SC), reduced air preheat (RAP), low NOX burners (LNBs), burning oil/water emulsions (OWE), or some
combination thereof may result in NOX reductions of 5 to 60 percent. Load reduction (LR) can likewise
decrease NOX production. Nitrogen oxide emissions may be reduced from 0.5 to 1 percent for each
percentage reduction in load from full load operation. It should be noted that most of these variables, with
the exception of excess air, only influence the NO* emissions of large oil-fired boilers. Low excess air-
firing is possible in many small boilers, but the resulting NOX reductions are less significant.
1.3.3.4 Carbon Monoxide Emissions29'32 -
The rate of carbon monoxide (CO) emissions from combustion sources depends on the oxidation
efficiency of the fuel. By controlling the combustion process carefully, CO emissions can be minimized.
Thus if a unit is operated improperly or not well maintained, the resulting concentrations of CO (as well as
organic compounds) may increase by several orders of magnitude. Smaller boilers, heaters, and furnaces
tend to emit more of these pollutants than larger combustors. This is because smaller units usually have a
higher ratio of heat transfer surface area to flame volume than larger combustors have; this leads to
reduced flame temperature and combustion intensity and, therefore, lower combustion efficiency.
The presence of CO in the exhaust gases of combustion systems results principally from
incomplete fuel combustion. Several conditions can lead to incomplete combustion, including insufficient
oxygen (O2) availability; poor fuel/air mixing; cold-wall flame quenching; reduced combustion
temperature; decreased combustion gas residence time; and load reduction (i. e., reduced combustion
9/98 External Combustion Sources 1.3-3
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intensity). Since various combustion modifications for NOX reduction can produce one or more of the
above conditions, the possibility of increased CO emissions is a concern for environmental, energy
efficiency, and operational reasons.
1.3.3.5 Organic Compound Emissions29"39 -
Small amounts of organic compounds are emitted from combustion. As with CO emissions, the
rate at which organic compounds are emitted depends, to some extent, on the combustion efficiency of the
boiler. Therefore, any combustion modification which reduces the combustion efficiency will most likely
increase the concentrations of organic compounds in the flue gases.
Total organic compounds (TOCs) include VOCs, semi-volatile organic compounds, and
condensable organic compounds. Emissions of VOCs are primarily characterized by the criteria pollutant
class of unbumed vapor phase hydrocarbons. Unburned hydrocarbon emissions can include essentially all
vapor phase organic compounds emitted from a combustion source. These are primarily emissions of
aliphatic, oxygenated, and low molecular weight aromatic compounds which exist in the vapor phase at
flue gas temperatures. These emissions include all alkanes, alkenes, aldehydes, carboxylic acids, and
substituted benzenes (e. g., benzene, toluene, xylene, and ethyl benzene).
The remaining organic emissions are composed largely of compounds emitted from combustion
sources in a condensed phase. These compounds can almost exclusively be classed into a group known as
polycyclic organic matter (POM), and a subset of compounds called polynuclear
aromatic hydrocarbons (PAH or PNA). There are also PAH-nitrogen analogs. Information available in the
literature on POM compounds generally pertains to these PAH groups.
Formaldehyde is formed and emitted during combustion of hydrocarbon-based fuels including coal
and oil. Formaldehyde is present in the vapor phase of the flue gas. Formaldehyde is subject to oxidation
and decomposition at the high temperatures encountered during combustion. Thus, larger units with
efficient combustion (resulting from closely regulated air-fuel ratios, uniformly high combustion chamber
temperatures, and relatively long gas retention times) have lower formaldehyde emission rates than do
smaller, less efficient combustion units.
1.3.3.6 Trace Element Emissions29'32'40^4 -
Trace elements are also emitted from the combustion of oil. For this update of AP-42, trace metals
included in the list of 189 hazardous air pollutants under Title IH of the 1990 Clean Air Act Amendments
are considered. The quantity of trace elements entering the combustion device depends solely on the fuel
composition. The quantity of trace metals emitted from the source depends on combustion temperature,
fuel feed mechanism, and the composition of the fuel. The temperature determines the degree of
volatilization of specific compounds contained in the fuel. The fuel feed mechanism affects the separation
of emissions into bottom ash and fly ash. In general, the quantity of any given metal emitted depends on
the physical and chemical properties of the element itself; concentration of the metal in the fuel; the
combustion conditions; and the type of paniculate control device used, and its collection efficiency as a
function of particle size.
Some trace metals concentrate in certain waste particle streams from a combustor (bottom ash,
collector ash, flue gas paniculate), while others do not. Various classification schemes to describe this
partitioning have been developed. The classification scheme used by Baig, et al.44 is as follows:
Class 1: Elements which are approximately equally distributed between fly ash and
bottom ash, or show little or no small particle enrichment.
1.3-4 EMISSION FACTORS 9/98
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Class 2: Elements which are enriched in fly ash relative to bottom ash, or show increasing
enrichment with decreasing particle size.
Class 3: Elements which are emitted in the gas phase:
By understanding trace metal partitioning and concentration in fine participate, it is possible to
postulate the effects of combustion controls on incremental trace metal emissions. For example, several
NOX controls for boilers reduce peak flame temperatures (e. g., SC, FOR, RAP, OWE, and LR). If
combustion temperatures are reduced, fewer Class 2 metals will initially volatilize, and fewer will be
available for subsequent condensation and enrichment on fine PM. Therefore, for combustors with
paniculate controls, lower volatile metal emissions should result due to improved particulate removal. Flue
gas emissions of Class 1 metals (the non-segregating trace metals) should remain relatively unchanged.
Lower local O2 concentrations is also expected to affect segregating metal emissions from boilers
with particle controls. Lower O2 availability decreases the possibility of volatile metal oxidation to less
volatile oxides. Under these conditions, Class 2 metals should remain in the vapor phase as they enter the
cooler sections of the boiler. More redistribution to small particles should occur and emissions should
increase. Again, Class 1 metal emissions should remain unchanged.
1.3.3.7 Greenhouse Gases45"50 -
Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions are all produced during
fuel oil combustion. Nearly all of the fuel carbon (99 percent) in fuel oil is converted to CO2 during the
combustion process. This conversion is relatively independent of firing configuration. Although the
formation of CO acts to reduce CO2 emissions, the amount of CO produced is insignificant compared to the
amount of CO2 produced. The majority of the fuel carbon not converted to CO2 is due to incomplete
combustion in the fuel stream.
Formation of N2O during the combustion process is governed by a complex series of reactions and
its formation is dependent upon many factors. Formation of N2O is minimized when combustion
temperatures are kept high (above 1475°F) and excess air is kept to a minimum (less than 1 percent).
Additional sampling and research is needed to fully characterize N2O emissions and to understand the N2O
formation mechanism. Emissions can vary widely from unit to unit, or even from the same unit at different
operating conditions. Average emission factors based on reported test data have been developed for
conventional oil combustion systems.
Methane emissions vary with the type of fuel and firing configuration, but are highest during
periods of incomplete combustion or low-temperature combustion, such as the start-up or shut-down cycle.
for oil-fired boilers. Typically, conditions that favor formation of N2O also favor emissions of CH4.
1.3.4 Controls
Control techniques for criteria pollutants from fuel oil combustion may be classified into three
broad categories: fuel substitution/alteration, combustion modification, and postcombustion control.
Emissions of noncriteria pollutants such as particulate phase metals have been controlled through the use of
post combustion controls designed for criteria pollutants. Fuel substitution reduces SO2 or NO, and
involves burning a fuel with a lower sulfur or nitrogen content, respectively. Particulate matter will
generally be reduced when a lighter grade of fuel oil is burned.6'8-11 Fuel alteration of heavy oils includes
mixing water and heavy oil using emulsifying agents for better atomization and lower combustion
temperatures. Under some conditions, emissions of NOX, CO, and PM may be reduced significantly.
Combustion modification includes any physical or operational change in the furnace or boiler and is applied
9/98 External Combustion Sources 1.3-5
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primarily for NO^ control purposes, although for small units, some reduction in PM emissions may be
available through improved combustion practice. Postcombustion control is a device after the combustion
of the fuel and is applied to control emissions of PM, SO2, and NOX.
1.3.4.1 Paniculate Matter Controls51 -
Control of PM emissions from residential and commercial units is accomplished by improving
burner servicing and improving oil atomization and combustion aerodynamics. Optimization of
combustion aerodynamics using a flame retention device, swirl, and/or recirculation is considered effective
toward achieving the triple goals of low PM emissions, low NOX emissions, and high thermal efficiency.
Large industrial and utility boilers are generally well-designed and well-maintained so that soot and
condensable organic compound emissions are minimized. Paniculate matter emissions are more a result of
emitted fly ash with a carbon component in such units. Therefore, postcombustion controls (mechanical
collectors, ESP, fabric filters, etc.) or fuel substitution/alteration may be used to reduce PM emissions from
these sources.
Mechanical collectors, a prevalent type of control device, are primarily useful in controlling
particulates generated during soot blowing, during upset conditions, or when a very dirty heavy oil is fired.
For these situations, high-efficiency cyclonic collectors can achieve up to 85 percent control of paniculate.
Under normal firing conditions, or when a clean oil is combusted, cyclonic collectors are not nearly so
effective because of the high percentage of small particles (less than 3 micrometers in diameter) emitted.
Electrostatic precipitators (ESPs) are commonly used in oil-fired power plants. Older
precipitators, usually small, typically remove 40 to 60 percent of the emitted PM. Because of the low ash
content of the oil, greater collection efficiency may not be required. Currently, new or rebuilt ESPs can
achieve collection efficiencies of up to 90 percent.
In fabric filtration, a number of filtering elements (bags) along with a bag cleaning system are
contained in a main shell structure incorporating dust hoppers. The paniculate removal efficiency of the
fabric filter system is dependent on a variety of particle and operational characteristics including particle
size distribution, particle cohesion characteristics, and particle electrical resistivity. Operational
parameters that affect collection efficiency include air-to-cloth ratio, operating pressure loss, cleaning
sequence, interval between cleaning, and cleaning intensity. The structure of the fabric filter, filter
composition, and bag properties also affect collection efficiency. Collection efficiencies of baghouses may
be more than 99 percent.
Scrubbing systems have also been installed on oil-fired boilers to control both sulfur oxides and
paniculate. These systems can achieve SO2 removal efficiencies of 90 to 95 percent and paniculate control
efficiencies of 50 to 60 percent.
Fuel alteration of heavy oil by mixing with water and an emulsifying agent has reduced PM
emissions significantly in controlled tests.
1.3.4.2 SO2 Controls52'53 -
Commercialized postcombustion flue gas desulfurization (FGD) processes use an alkaline reagent
to absorb SO2 in the flue gas and produce a sodium or a calcium sulfate compound. These solid sulfate
compounds are then removed in downstream equipment. Flue gas desulfurization technologies are
categorized as wet, semi-dry, or dry depending on the state of the reagent as it leaves the absorber vessel.
These processes are either regenerable (such that the reagent material can be treated and reused) or
nonregenerable (in which case all waste streams are de-watered and discarded).
1.3-6 EMISSION FACTORS 9/98
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Wet regenerable FGD processes are attractive because they have the potential for better than
95 percent sulfur removal efficiency, have minimal waste water discharges, and produce a saleable sulfur
product. Some of the current nonregenerable calcium-based processes can, however, produce a saleable
gypsum product.
To date, wet systems are the most commonly applied. Wet systems generally use alkali slurries as
the SOX absorbent medium and can be designed to remove greater than 90 percent of the incoming SOX.
Lime/limestone scrubbers, sodium scrubbers, and dual alkali scrubbing are among the commercially proven
wet FGD systems. Effectiveness of these devices depends not only on control device design but also on
operating variables.
1.3.4.3 NOX Controls41'54-55 -
In boilers fired on crude oil or residual oil, the control of fuel NOX is very important in achieving
the desired degree of NOX reduction since fuel NOX typically accounts for 60 to 80 percent of the total NOX
formed. Fuel nitrogen conversion to NOX is highly dependent on the fuel-to-air ratio in the combustion zone
and, in contrast to thermal NOX formation, is relatively insensitive to small changes in combustion zone
temperature. In general, increased mixing of fuel and air increases nitrogen conversion which, in turn,
increases fuel NOX. Thus, to reduce fuel NOX formation, the most common combustion modification
technique is to suppress combustion air levels below the theoretical amount required for complete
combustion. The lack of oxygen creates reducing conditions that, given sufficient time at high
temperatures, cause volatile fuel nitrogen to convert to N2 rather than NO.
Several techniques are used to reduce NOX emissions from fuel oil combustion. Fuel substitution
consists of burning lower nitrogen fuels. Fuel alteration includes burning emulsified heavy oil and water
mixtures. In addition to these, the primary techniques can be classified into one of two fundamentally
different methods — combustion controls and postcombustion controls. Combustion controls reduce NOX
by suppressing NOX formation during the combustion process while postcombustion controls reduce NOX
emissions after their formation. Combustion controls are the most widely used method of controlling NOX
formation in all types of boilers and include low excess air, burners out of service, biased-burner firing,
flue gas recirculation, overfire air, and low-NOx burners. Postcombustion control methods include
selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR). These controls can be
used separately, or combined to achieve greater NOX reduction.
Operating at low excess air involves reducing the amount of combustion air to the lowest possible
level while maintaining efficient and environmentally compliant boiler operation. NOX formation is
inhibited because less oxygen is available in the combustion zone. Burners out of service involves
withholding fuel flow to all or part of the top row of burners so that only air is allowed to pass through.
This method simulates air staging, or overfire air conditions, and limits NO,, formation by lowering the
oxygen level in the burner area. Biased-burner firing involves firing the lower rows of burners more fuel-
rich than the upper row of burners. This method provides a form of air staging and limits NOX formation
by limiting the amount of oxygen in the firing zone. These methods may change the normal operation of
the boiler and the effectiveness is boiler-specific. Implementation of
these techniques may also reduce operational flexibility; however, they may reduce NOX by 10 to
20 percent from uncontrolled levels.
Flue gas recirculation involves extracting a portion of the flue gas from the economizer section or
air heater outlet and readmitting it to the furnace through the furnace hopper, the burner windbox, or both.
This method reduces the concentration of oxygen in the combustion zone and may reduce NOX by as much
as 40 to 50 percent in some boilers.
9/98 External Combustion Sources 1.3-7
-------
Overfire air is a technique in which a percentage of the total combustion air is diverted from the
burners and injected through ports above the top burner level. Overfire air limits NOX by
(1) suppressing thermal NOX by partially delaying and extending the combustion process resulting in less
intense combustion and cooler flame temperatures; (2) a reduced flame temperature that limits thermal NO*
formation, and/or (3) a reduced residence time at peak temperature which also limits thermal NOX
formation.
Low NOX burners are applicable to tangential and wall-fired boilers of various sizes. They have
been used as a retrofit NOX control for existing boilers and can achieve approximately 35 to 55 percent
reduction from uncontrolled levels. They are also used in new boilers to meet NSPS limits. Low NOX
burners can be combined with overfire air to achieve even greater NOX reduction (40 to 60 percent
reduction from uncontrolled levels).
SNCR is a postcombustion technique that involves injecting ammonia or urea into specific
temperature zones in the upper furnace or convective pass. The ammonia or urea reacts with NOX in the
flue gas to produce nitrogen and water. The effectiveness of SNCR depends on the temperature where
reagents are injected; mixing of the reagent in the flue gas; residence time of the reagent within the required
temperature window; ratio of reagent to NOX; and the sulfur content of the fuel that may create sulfur
compound that deposit in downstream equipment. There is not as much commercial experience to base
effectiveness on a wide range of boiler types; however, in limited applications, NOX reductions of 25 to 40
percent have been achieved.
SCR is another postcombustion technique that involves injecting ammonia into the flue gas in the
presence of a catalyst to reduce NOX to nitrogen and water. The SCR reactor can be located at various
positions in the process including before an air heater and particulate control device, or downstream of the
air heater, particulate control device, and flue gas desulfurization systems. The performance of SCR is
influenced by flue gas temperature, fuel sulfur content, ammonia to NOX ratio, inlet NOX concentration,
space velocity, and catalyst condition. NOX emission reductions of 75 to 85 percent have been achieved
through the use of SCR on oil-fired boilers operating in the U.S.
Fuel alteration for NOX reduction includes use of oil/water emulsion fuels, hi controlled tests, a
mixture of 9 percent water in No. 6 oil with a petroleum based emulsifying agent reduced NOX emissions
by 36 percent on a Btu basis or 41 percent on a volume basis, compared with the same fuel in unaltered
form. The reduction appears to be due primarily to improved atomization with a corresponding reduction
of excess combustion air, with lower flame temperature contributing slightly to the reduction.84
Tables 1.3-1 and 1.3-3 present emission factors for uncontrolled criteria pollutants from fuel oil
combustion. Tables in this section present emission factors on a volume basis (Ib/lO'gal). To convert to
an energy basis (Ib/MMBtu), divide by a heating value of 150 MMBtu/ltfgal for Nos. 4, 5, 6, and residual
fuel oil, and 140 MMBtu/103gal for No. 2 and distillate fuel oil. Table 1.3-2 presents emission factors for
condensible particulate matter. Tables 1.3-4, 1.3-5, 1.3-6, and 1.3-7 present cumulative size distribution
data and size-specific emission factors for particulate emissions from uncontrolled and controlled fuel oil
combustion. Figures 1.3-1,1.3-2, 1.3-3, and 1.3-4 present size-specific emission factors for particulate
emissions from uncontrolled and controlled fuel oil combustion. Emission factors for N2O, POM, and
formaldehyde are presented in Table 1.3-8. Emission factors for speciated organic compounds are
presented in Table 1.3-9. Emission factors for trace elements in distillate oil are given in Table 1.3-10.
Emission factors for trace metals residual oil are given in Table 1.3-11. Default emission factors for CO2
are presented in Table 1.3-12. A summary of various SO2 and NOX controls for fuel-oil-fired boilers is
presented in Table 1.3-13 and 1.3-14, respectively. Emission factors for CO, NOX, and PM from burning
No. 6 oil/water emulsion fuel are presented in Table 1.3-15.
1.3-8 EMISSION FACTORS 9/98
-------
1.3.5 Updates Since the Fifth Edition
The Fifth Edition was released in January 1995. Revisions to this section since that date are
summarized below. For further detail, consult the memoranda describing each supplement or the
background report for this section. These and other documents can be found on the EFIG home page
(http://www.epa.gov/oar/oaqps/efig/).
Supplement A, February 1996
• The formulas presented in the footnotes for filterable PM were moved into the table.
• For SO2 and SO3 emission factors, text was added to the table footnotes to clarify that "S"
is a weight percent and not a fraction. A similar clarification was made to the CO and
NOX footnotes. SCC A2104004/A2104011 was provided for residential furnaces.
• For industrial boilers firing No. 6 and No. 5 oil, the methane emission factor was changed
from 1 to 1.0 to show two significant figures.
• For SO2 and SO3 factors, text was added to the table footnotes to clarify that "S" is a
weight percent and not a fraction.
• The N2O, POM, and formaldehyde factors were corrected.
• Table 1.3-10 was incorrectly labeled 1.1-10. This was corrected.
Supplement B, October 1996
• Text was added concerning firing practices.
• Factors for N2O, POM, and formaldehyde were added.
• New data for filterable PM were used to create a new PM factor for residential oil-fired
furnaces.
• Many new factors were added for toxic organics, toxic metals from distillate oil, and toxic
metals from residual oil.
• A table was added for new CO2 emission factors.
Supplement E, September 1998
• Table 1.3-1, the sub-heading for "Industrial Boilers" was added to the first column.
• Table 1.3-3, the emission factor for uncontrolled PM less than 0.625 micron was corrected
to 1.7A, the emission factor for scrubber controlled PM less than 10 micron was corrected
to 0.50A, and the relationships for each content in various fuel oils was corrected in
footnote C.
• Table 1.3-4 and 1.3-6, the relationship for ash content in various fuel oils was corrected in
the footnote C of each table.
9/98 External Combustion Sources 1.3-9
-------
Table 1.3-9, the emission factors for trace metals in distillate oil were updated with newer
data where available.
1.3-10, the title of the table was changed to clarify these factors apply to uncontrolled fuel
oil boilers.
Text and emission factors were added pertaining to No. 6 oil/water emulsion fuel.
Table 1.3-1 was revised to include new NOX emission factors.
Emission factors for condensable particulate matter were added (Table 1.3-2).
1.3-10 EMISSION FACTORS 9/98
-------
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1.3-12
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9/98
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9/98
External Combustion Sources
1.3-13
-------
Table 1.3-3. EMISSION FACTORS FOR TOTAL ORGANIC COMPOUNDS
(TOC), METHANE, AND NONMETHANE TOC (NMTOC) FROM UNCONTROLLED
FUEL OIL COMBUSTION3
EMISSION FACTOR RATING: A
Firing Configuration
(SCC)
Utility boilers
No. 6 oil fired, normal firing (1-01-004-01)
No. 6 oil fired, tangential firing (1-01-004-04)
No. 5 oil fired, normal firing (1-01-004-05)
No. 5 oil fired, tangential firing (1-01-004-06)
No. 4 oil fired, normal firing (1-01-005-04)
No. 4 oil fired, tangential firing (1-01-005-05)
Industrial boilers
No. 6 oil fired (1-02-004-01/02/03)
No. 5 oil fired (1-02-004-04)
Distillate oil fired (1-02-005-01/02/03)
No. 4 oil fired (1-02-005-04)
Commercial/institutional/residential combustors
No. 6 oil fired (1-03-004-01/02/03)
No. 5 oil fired (1-03-004-04)
Distillate oil fired (1-03-005-01/02/03)
No. 4 oil fired (1-03-005-04)
Residential furnace (A2104004/A2104011)
TOCb
Emission
Factor
(lb/103 gal)
1.04
1.04
1.04
1.04
1.04
1.04
1.28
1.28
0.252
0.252
1.605
1.605
0.556
0.556
2.493
Methaneb
Emission
Factor
(lb/103 gal)
0.28
0.28
0.28
0.28
0.28
0.28
1.00
1.00
0.052
0.052
0.475
0.475
0.216
0.216
1.78
NMTOCb
Emission
Factor
(lb/103 gal)
0.76
0.76
0.76
0.76
0.76
0.76
0.28
0.28
0.2
0.2
1.13
1.13
0.34
0.34
0.713
To convert from lb/103 gal to kg/103 L, multiply by 0.12. SCC = Source Classification
b References 29-32. Volatile organic compound emissions can increase by several orders
the boiler is improperly operated or is not well maintained.
Code.
of magnitude if
1.3-14
EMISSION FACTORS
9/98
-------
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External Combustion Sources
1.3-15
-------
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1.3-16
EMISSION FACTORS
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9/98
-------
Table 1.3-6. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS FOR UNCONTROLLED INDUSTRIAL BOILERS FIRING
DISTILLATE OILa
EMISSION FACTOR RATING: E
Particle Sizeb (^m)
15
10
6
2.5
1.25
1.00
0.625
TOTAL
Cumulative Mass % s Stated Size
68
50
30
12
9
8
2
100
Cumulative Emission Factor
(lb/103 gal)
1.33
1.00
0.58
0.25
0.17
0.17
0.04
2.00
Reference 26. Source Classification Codes 1-02-005-01/02/03. To convert from lb/103 gal to kg/103 L,
multiply by 0.12.
b Expressed as aerodynamic equivalent diameter.
Table 1.3-7. CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS UNCONTROLLED COMMERCIAL BOILERS
BURNING RESIDUAL OR DISTILLATE OIL"
EMISSION FACTOR RATING: D
Particle
Size" Om)
15
10
6
2.5
1.25
1.00
0.625
TOTAL
Cumulative Mass % & Stated Size
Residual
Oil
78
62
44
23
16
14
13
100
Distillate
Oil
60
55
49
42
38
37
35
100
Cumulative Emission Factor0
(lb/103 gal)
Residual
Oil
6.50A
5.17A
3.67A
1.92A
1.33A
1.17A
1.08 A
8.34A
Distillate
Oil
1.17
1.08
1.00
0.83
0.75
0.75
0.67
2.00
a Reference 26. Source Classification Codes: 1-03-004-01/02/03/04 and 1-03-005-01/02/03/04. To
convert from lb/103 gal to kg/103 L, multiply by 0.12.
b Expressed as aerodynamic equivalent diameter.
c Particulate emission factors for residual oil combustion without emission controls are, on average, a
function of fuel oil grade and sulfur content where S is the weight % of sulfur in the fuel. For example, if
the fuel is 1.0% sulfur, then S = 1.
No. 6 oil: A = 1.12(S) + 0.37 No. 4 oil: A = 0.84
No. 5 oil: A = 1.2 No. 2 oil: A = 0.24
9/98
External Combustion Sources
1.3-17
-------
l.OA
0.9A
0.8A
0.7A
0.6A
0.5A
0.4A
0.3A
0.2A
0.1A
0
ESP
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0.0006A | *
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0.0001A
Particle diameter ( m)
Figure 1.3-1. Cumulative size-specific emission factors for utility boilers firing residual oil.
.
°
' f
I
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u
s
i
g
§
'
OA
40 60 100
Particle diameter ( m)
Figure 1.3-2. Cumulative size-specific emission factors for industrial boilers firing residual oil.
1.3-18
EMISSION FACTORS
9/98
-------
0.25
0.20
'a Cj 0.15
1*2
•o ^ 0.10
0.05
.1 .2 .4 .6 1
4 6 10 20 40 60 100
Particle diameter ( m)
Figure 1.3-3. Cumulative size-specific emission factors for uncontrolled industrial boilers firing
distillate oil.
1
1.00 A
0.90A
0.80A
0.70A
1
0.30A
0.20A
0.1 OA
0
Distillate oil
\
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T5b
o.io -g |
0.05
0
.1 .2 .4 .6 1
4 6 10 20 40 60 100
Particle diameter ( m)
Figure 1.3-4. Cumulative size-specific emission factors for uncontrolled commercial boilers
burning residual and distillate oil.
9/98
External Combustion Sources
1.3-19
-------
Table 1.3-8. EMISSION FACTORS FOR NITROUS OXIDE (N2O),
POLYCYCLIC ORGANIC MATTER (POM), AND FORMALDEHYDE (HCOH)
FROM FUEL OIL COMBUSTION3
EMISSION FACTOR RATING: E
Firing Configuration
(SCC)
Utik'ty/industrial/commercial boilers
No. 6 oil fired
(1-01-004-01, 1-02-004-01, 1-03-004-01)
Distillate oil fired
(1-01-005-01, 1-02-005-01, 1-03-005-01)
Residential furnaces (A2104004/A2104011)
Emission Factor (lb/103 gal)
N2Ob
0.11
0.11
0.05
POMC
0.0011-0.0013"
0.0033e
ND
HCOHC
0.024 - 0.061
0.035 - 0.061
ND
To convert from lb/103 gal to kg/103 L, multiply by 0.12. SCC = Source Classification Code. ND = no
data.
b References 45-46. EMISSION FACTOR RATING = B.
c References 29-32.
d Particulate and gaseous POM.
e Particulate POM only.
1.3-20
EMISSION FACTORS
9/98
-------
Table 1.3-9. EMISSION FACTORS FOR SPECIATED ORGANIC COMPOUNDS
FROM FUEL OIL COMBUSTION3
Organic Compound
Benzene
Ethylbenzene
Formaldehyde*1
Naphthalene
1,1,1 -Trichloroethane
Toluene
o-Xylene
Acenaphthene
Acenaphthylene
Anthracene
Benz(a)anthracene
Benzo(b,k)fluoranthene
Benzo(g,h,i)perylene
Chrysene
Dibenzo(a,h) anthracene
Fluoranthene
Fluorene
Indo( 1 ,2,3-cd)pyrene
Phenanthrene
Pyrene
OCDD
Average Emission
Factorb
(lb/103 Gal)
2.14E-04
6.36E-050
3.30E-02
1.13E-03
2.36E-040
6.20E-03
1.09E-04C
2.11E-05
2.53E-07
1.22E-06
4.01E-06
1.48E-06
2.26E-06
2.38E-06
1.67E-06
4.84E-06
4.47E-06
2.14E-06
1.05E-05
4.25E-06
3.10E-09C
EMISSION
FACTOR
RATING
C
E
C
C
E
D
E
C
D
C
C
C
C
C
D
C
C
C
C
C
E
a Data are for residual oil fired boilers, Source Classification Codes (SCCs) 1-01-004-01/04.
b References 64-72. To convert from lb/103 gal to kg/103 L, multiply by 0.12.
0 Based on data from one source test (Reference 67).
d The formaldehyde number presented here is based only on data from utilities using No. 6 oil. The
number presented in Table 1.3-7 is based on utility, commercial, and industrial boilers.
9/98
External Combustion Sources
1.3-21
-------
ri
H
oo
>-H
Q
S
O
e w
£ w
Q u
^
J O
W oo
ACTORS FOR TRACE
iL OIL COMBUSTION
Hi K
1
CO
k— t
w
o
W
O
z
HH
H
MISSION FACTOR RA
w
3
(N
"O
§
O
t3
t^«
£2
_o
X
E
w
=
PN
•a
c
SS
_H-
o
o
o
01
o
1
0
>A
o
1
""*
1
u
o .
oo ^
-------
Table 1.3-11. EMISSION FACTORS FOR METALS FROM UNCONTROLLED NO. 6
FUEL OIL COMBUSTION3
Metal
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chloride
Chromium
Chromium VI
Cobalt
Copper
Fluoride
Lead
Manganese
Mercury
Molybdenum
Nickel
Phosphorous
Selenium
Vanadium
Zinc
Average Emission Factor1"' d
(lb/103 Gal)
5.25E-030
1.32E-03
2.57E-03
2.78E-05
3.98E-04
3.47E-01
8.45E-04
2.48E-04
6.02E-03
1.76E-03
3.73E-02
1.51E-03
3.00E-03
1.13E-04
7.87E-04
8.45E-02
9.46E-03
6.83E-04
3.18E-02
2.91E-02
EMISSION FACTOR
RATING
E
C
D
C
C
D
C
C
D
C
D
C
C
C
D
C
D
C
D
D
a Data are for residual oil fired boilers, Source Classification Codes (SCCs) 1-01-004-01/04.
b References 64-72. 18 of 19 sources were uncontrolled and 1 source was controlled with low efficiency
ESP. To convert from lb/103 gal to kg/103 L, multiply by 0.12.
c References 29-32,40-44.
d For oil/water mixture, reduce factors in proportion to water content of the fuel (due to dilution). To
adjust the listed values for water content, multiply the listed value by 1-decimal fraction of water (ex: For
fuel with 9 percent water by volume, multiply by 1-0.9=.91).
9/98
External Combustion Sources
1.3-23
-------
Table 1.3-12. DEFAULT CO2 EMISSION FACTORS FOR LIQUID FUELS3
EMISSION FACTOR RATING: B
Fuel Type
No. 1 (kerosene)
No. 2
Low Sulfur No. 6
High Sulfur No. 6
%cb
86.25
87.25
87.26
85.14
Density6
(Ib/gal)
6.88
7.05
7.88
7.88
Emission Factor (lb/103
gal)
21,500
22,300
25,000
24,400
a Based on 99% conversion of fuel carbon content to CO2. To convert from Ib/gal to gram/cm3, multiply
by 0.12. To convert from lb/103 gal to kg/m3, multiply by 0.12.
b Based on an average of fuel carbon contents given in references 73-74.
c References 73, 75.
1.3-24
EMISSION FACTORS
9/98
-------
Table 1.3-13. POSTCOMBUSTION SO, CONTROLS FOR FUEL OIL COMBUSTION SOURCES
Control Technology
Wet scrubber
Spray drying
Furnace injection
Duct injection
Process
Lime/limestone
Sodium carbonate
Magnesium
oxide/hydroxide
Dual alkali
Calcium hydroxide
slurry, vaporizes in
spray vessel
Dry calcium
carbonate/hydrate
injection in upper
furnace cavity
Dry sorbent injection
into duct, sometimes
combined with water
spray
Typical Control
Efficiencies
80-95+%
80-98%
80-95+%
90-96%
70-90%
25-50%
25-50+%
Remarks
Applicable to high-sulfur
fuels, Wet sludge product
5-430 MMBtu/hr typical
application range, High reagent
costs
Can be regenerated
Uses lime to regenerate
sodium-based scrubbing
liquor
Applicable to low -and
medium-sulfur fuels,
Produces dry product
Commercialized in Europe,
Several U.S. demonstration
projects underway
Several R&D and
demonstration projects
underway, Not yet
Commercially available in the
U.S.
9/98
External Combustion Sources
1.3-25
-------
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Q
^,
2
JS on
5 3
ra *-
> 2
< C/3
•a Q
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S «
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a|
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c
u
0
OH
c ^
o •»- •
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1
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Generally excess O2
can be reduced to
2.5% representing a
3% drop from
baseline
S
o
o
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cs
o
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C
(A
1
O
u
o
c
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Best implemented on new
units. Retrofit is probably r
feasible for most units,
especially packaged ones.
§1 £
3 S ~
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a 2 c -g
o.^ ^ > .
>
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? C
11
C
o
tfl
tl^
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Requires careful selection o
BOOS pattern and control c
air flow. May result in boil
de-rating unless fuel delivei
system is modified.
—
«
'a
^
<
Most effective on
boilers with 4 or
more burners in a
square pattern.
Q
Z
o
o
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u £
a g
§|
u o
1 fe
III
o £ *
S Oi S
0 . 00
o >% c
3
> s
< c
Up to 25-30% of
flue gas recycled.
Can be implemented
on most design
types.
fO
o
oo
O
tn
O
in
u
3
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implemented on new units.
£
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11
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Maximum FOR
rates set at 25% for
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r-
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1.3-26
EMISSION FACTORS
9/98
-------
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ca
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9/98
External Combustion Sources
1.3-27
-------
o
u
1
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A smaller version of
conventional SCR is p
existing ductwork
Duct SCR
h pressure drop.
ao
£
^
"u
^H
^
^_,
o
B
"S 2
_O tn
IS C
s o
l-s
u
&0 tn
is c
" b£
"rt "^
y fe
d. 772
H.S
O
Q
Z
l-
-r '3
^ ^
Activated carbon catal
installed downstream (
heater.
Activated Carbon
SCR
•o
u
3
rmal efficiency
to water conteni
lS|
^
"o
^
'i
I
1!
f^ w
U
12
u
1
XI
3
£-
E
Q
Z
5
E
,^
'tn
"3
Oil/water fuel with em
agent
1 Oil/Water
Emulsified Fuel"'b
i
ler was a 2400 1
I
H
E
U
00
a
WJ
c
|>>
'tn
"3
u
T3
E
g
o
t
rt
60
E
• -.
—
O
O
13
c
8.
ON
u.
1
1
C3
•a CQ
-So
£ "—
o x
ex f^
A using commercially
2 firetube type, fired at
°- c
OJ -g
i^ ra
' ND = nodata.
b Test conducted b;
15 psig Scotch M
1.3-28
EMISSION FACTORS
9/98
-------
Table 1.3-15. EMISSION FACTORS FOR NO. 6 OIL/WATER EMULSION IN
INDUSTRIAI7COMMERCIAL/INSTITUTIONAL BOILERS3
Pollutant
CO
NOX
PM
Emission Factor
(Ib/103 gal)
1.90
38.0
14.9
Factor Rating
C
C
C
Comments
33% Reduction from plain oil
41% Reduction
45% Reduction
Test conducted by EPA using commercially premixed fuel and water (9 percent water) containing a
petroleum based emulsifying agent. Test boiler was a 2400 Ib/hr, 15 psig Scotch Marine firetube type,
fired at 2 x 106 Btu/hr.
9/98
External Combustion Sources
1.3-29
-------
References For Section 1.3
1. W. S. Smith, Atmospheric Emissions From Fuel Oil Combustion: An Inventory Guide,
999-AP-2, U. S. Environmental Protection Agency, Washington, DC, November 1962.
2. J. A. Danielson (ed.), Air Pollution Engineering Manual, Second Edition, AP-40,
U. S. Environmental Protection Agency, Research Triangle Park, NC, 1973. Out of Print.
3. Fossil Fuel Fired Industrial Boilers — Background Information: Volume 1,
EPA-450/3-82-006a, U. S. Environmental Protection Agency, Research Triangle Park, NC, March
1982.
4. Emission Factor Documentation For AP-42, Section 1.3, Fuel Oil Combustion, Office of Air
- Quality Planning and Standards, U. S. Environmental Protection Agency, Research Triangle Park,
NC, April 1993.
5. U. S. Environmental Protection Agency, "National Primary and Secondary Ambient Air Quality
Standards", Code of Federal Regulations, Title 40, Part 50, U. S. Government Printing Office,
Washington DC, 1991.
6. A. Levy, et al., A Field Investigation Of Emissions From Fuel Oil Combustion For Space
Heating, API Bulletin 4099, Battelle Columbus Laboratories, Columbia, OH, November 1971.
7. R. E. Barrett, et al,, Field Investigation Of Emissions From Combustion Equipment For Space
Heating, EPA-R2-73-084a, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 1973.
8. G. A. Cato, et al., Field Testing: 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.
9. G. A. Cato, et al., Field Testing: Application Of Combustion Modifications To Control Pollutant
Emissions From Industrial Boilers—Phase II, EPA-600/ 2-76-086a, U. S. Environmental
Protection Agency, Washington, DC, April 1976.
10. Particulate Emission Control Systems For Oil Fired Boilers, EPA-450/3-74-063,
U. S. Environmental Protection Agency, Research Triangle Park, NC, December 1974.
11. C. W. Siegmund, "Will Desulfurized Fuel Oils Help?", American Society Of Heating,
Refrigerating And Air Conditioning Engineers Journal, 11:29-33, April 1969.
12. F. A. Govan, et al., "Relationships of Particulate Emissions Versus Partial to Full Load
Operations for Utility-sized Boilers", Proceedings Of Third Annual Industrial Air Pollution
Control Conference, Knoxville, TN, March 29-30, 1973.
13. Emission Test Reports, Docket No. OAQPS-78-1, Category II-I-257 through 265, Office Of Air
Quality Planning And Standards, U. S. Environmental Protection Agency, Research Triangle Park,
NC, 1972 through 1974.
1.3-30 EMISSION FACTORS 9/98
-------
14. C. Leavitt, et al., Environmental Assessment Of An Oil Fired Controlled Utility Boiler,
EPA-600/7-80-087, U. S. Environmental Protection Agency, Washington, DC, April 1980.
15. W. A. Carter and R. J. Tidona, Thirty-day Field Tests of Industrial Boilers:
Site 2—Residual-oil-fired Boiler, EPA-600/7-80-085b, U. S. Environmental Protection Agency,
Washington, DC, April 1980.
16. Primary Sulfate Emissions From Coal And Oil Combustion, EPA Contract No. 68-02-3138,
TRW, Inc., Redondo Beach, CA, February 1980.
17. W. Bartok, et al., Systematic Field Study OfNOx Emission Control Methods For Utility Boilers,
APTD-1163, U. S. Environmental Protection Agency, Research Triangle Park, NC, December
1971.
18. A. R. Crawford, et al., Field Testing: Application Of Combustion Modifications To Control NOX
Emissions From Utility Boilers, EPA-650/2-74-066, U. S. Environmental Protection Agency,
Washington, DC, June 1974.
19. J. F. Deffner, et al., Evaluation Of Gulf Econojet Equipment With Respect To Air Conservation,
Report No. 731RC044, Gulf Research and Development Company,
Pittsburgh, PA, December 18, 1972.
20. C. E. Blakeslee and H.E. Burbach, "Controlling NOX Emissions From Steam Generators," Journal
Of The Air Pollution Control Association, 23:37-42, January 1973.
21. R. E. Hall, et al., A Study Of Air Pollutant Emissions From Residential Heating Systems,
EPA-650/2-74-003, U. S. Environmental Protection Agency, Washington, DC, January 1974.
22. R. J. Milligan, et al., Review OfNOx Emission Factors For Stationary Fossil Fuel Combustion
Sources, EPA-450/4-79-021, U. S. Environmental Protection Agency, Research Triangle Park,
NC, September 1979.
23. K. J. Lim, et al., Technology Assessment Report For Industrial Boiler Applications: NOX
Combustion Modification, EPA-600/7-79-178f, U. S. Environmental Protection Agency,
Washington, DC, December 1979.
24. D. W. Pershing, et al., Influence Of Design Variables On The Production Of Thermal And Fuel
NO From Residual Oil And Coal Combustion, Air: Control of NOX and SOX Emissions, New
York, American Institute of Chemical Engineers, 1975.
25. R. Clayton, et al., N2O Field Study, EPA-600/2-89-006, U. S. Environmental Protection Agency,
Research Triangle Park, NC, February 1989.
26. Evaluation Of Fuel-Based Additives For N2O And Air Toxic Control In Fluidized Bed
Combustion Boilers, EPRI Contract No. RP3197-02, Acurex Report No. FR-91-101-/ESD,
(Draft Report) Acurex Environmental, Mountain View, CA, June 17, 1991.
27. Code of Federal Regulations 40, Parts 53 to 60, July 1, 1991.
9/98 External Combustion Sources 1.3-31
-------
28. James Ekmann, et al., Comparison Of Shale Oil And Residual Fuel Combustion, In Symposium
Papers, New Fuels And Advances In Combustion Technologies, Sponsored By Institute Of Gas
Technology, March 1979.
29. N. F. Suprenant, et al., Emissions Assessment Of Conventional Stationary Combustion Systems,
Volume I: Gas And Oil Fired Residential Heating Sources, EPA-600/7-79-029b, U. S.
Environmental Protection Agency, Washington, DC, May 1979.
30. C. C. Shih, et al., Emissions Assessment Of Conventional Stationary Combustion Systems,
Volume III: External Combustion Sources For Electricity Generation, EPA Contract
No. 68-02-2197, TRW, Inc., Redondo Beach, CA, November 1980.
31. N. F. Suprenant, et al., Emissions Assessment Of Conventional Stationary Combustion System,
Volume IV: Commercial Institutional Combustion Sources, EPA Contract No. 68-02-2197, GCA
Corporation, Bedford, MA, October 1980.
32. N. F. Suprenant, et al., Emissions Assessment Of Conventional Stationary Combustion Systems,
Volume V: Industrial Combustion Sources, EPA Contract No. 68-02-2197,
GCA Corporation, Bedford, MA, October 1980.
33. Paniculate Poly cyclic Organic Matter, National Academy of Sciences, Washington, DC, 1972.
34. Vapor Phase Organic Pollutants—Volatile Hydrocarbons And Oxidation Products, National
Academy of Sciences, Washington, DC, 1976.
35. H. Knierien, A Theoretical Study Of PCS Emissions From Stationary Sources,
EPA-600/7-76-028, U. S. Environmental Protection Agency, Research Triangle Park, NC,
September 1976.
36. Estimating Air Toxics Emissions From Coal And Oil Combustion Sources, EPA-450/2-89-001,
U. S. Environmental Protection Agency, Research Triangle Park, NC, April 1989.
37. R. P. Hagebrauck, D. J. Von Lehmden, and J. E. Meeker, "Emissions of Polynuclear
Hydrocarbons and Other Pollutants from Heat-Generation and Incineration Process",
J. Air Pollution Control Assoc., 14:267-278, 1964.
38. M. B. Rogozen, et al., Formaldehyde: A Survey Of Airborne Concentration And Sources,
California Air Resources Board, ARB Report No. ARB/R-84-231, 1984.
39. Seeker, W.R, et al, Municipal Waste Combustion Study: Combustion Control OfMSW
Combustors To Minimize Emissions Of Trace Organics, EPA-543-SW-87-021c,
U. S. Environmental Protection Agency, Washington, D.C., May 1987.
40. Clean Air Act Amendments of 1990, Conference Report To Accompany S.1603, Report 101-952,
U. S. Government Printing Office, Washington, DC, October 26, 1990.
41. K. J. Lim, et al., Industrial Boiler Combustion Modification NOX Controls - Volume I
Environmental Assessment, EPA-600/7-81-126a, U. S. Environmental Protection Agency, July
1981.
1.3-32 EMISSION FACTORS 9/98
-------
42. D. H. Klein, et al., "Pathways of Thirty-Seven Trace Elements Through Coal-Fired Power Plants,"
Environ. Sci. Technol., 9:973-979, 1975.
43. D. G. Coles, et al., "Chemical Studies of Stack Fly Ash From a Coal-Fired Power Plant," Environ.
Sci. Technol., 13:455-459, 1979.
44. S. Baig, et al., Conventional Combustion Environmental Assessment, EPA Contract
No. 68-02-3138, U. S. Environmental Protection Agency, Research Triangle Park, NC, 1981.
45. L. P. Nelson, et al., Global Combustion Sources of Nitrous Oxide Emissions, Research Project
2333-4 Interim Report, Sacramento: Radian Corporation.
46. R. L. Peer, et al., Characterization of Nitrous Oxide Emission Sources, Prepared for the
U. S. EPA Contract 68-D1-0031, Research Triangle Park, NC: Radian Corporation, 1995.
47. S. D. Piccot, et al., Emissions and Cost Estimates for Globally Significant Anthropogenic
Combustion Sources ofNO» N2O, CH4, CO, and CO2, EPA Contract No. 68-02-4288, Research
Triangle Park, NC: Radian Corporation, 1990.
48. G. Marland and R.M. Rotty, Carbon Dioxide Emissions from Fossil Fuels: A Procedure For
Estimation And Results For 1951-1981, DOE/NBB-0036 TR-003, Carbon Dioxide Research
Division, Office of Energy Research, U.S. Department of Energy, Oak Ridge, TN, 1983.
49. G. Marland and R.M. Rotty, Carbon Dioxide Emissions from Fossil Fuels: A Procedure For
Estimation And Results For 1950-1982, Tellus, 36B: 232-261.
50. Sector-Specific Issues and Reporting Methodologies Supporting the General Guidelines for the
Voluntary Reporting of Greenhouse Gases under Section 1605(b) of the Energy Policy Act of
1992 (1994) DOE/PO-0028, Volume 2 of 3, U.S. Department of Energy.
51. G. R. Offen, et al., Control Of Paniculate Matter From Oil Burners And Boilers,
EPA-450/3-76-005, U. S. Environmental Protection Agency, Research Triangle Park, NC, April
1976.
52. D. W. South, et al., Technologies And Other Measures For Controlling Emissions:
Performance, Costs, And Applicability, Acidic Deposition: State of Science and Technology,
Volume IV, Report 25, National Acid Precipitation Assessment Program, U. S. Government
Printing Office, Washington, DC, December 1990.
53. EPA Industrial Boiler FGD Survey: First Quarter 1979, EPA-600/7-79-067b,
U. S. Environmental Protection Agency, April 1979.
54. J. H. Pohl and A.F. Sarofim, Devolatilization And Oxidation Of Coal Nitrogen (Presented At The
16th International Symposium On Combustion), August 1976.
55. P. B. Nutcher, High Technology Low NOX Burner Systems For Fired Heaters And Steam
Generators, Process Combustion Corp., Pittsburgh, PA, Presented at the Pacific Coast Oil Show
and Conference, Los Angeles, CA, November 1982.
9/98 External Combustion Sources 1.3-33
-------
56. Environmental Assessment Of Coal And Oil Firing In A Controlled Industrial Boiler, Volume I,
PB 289942, U. S. Environmental Protection Agency, August 1978.
57. Environmental Assessment Of Coal And Oil Firing In A Controlled Industrial Boiler, Volume II,
EPA-600/7-78-164b, U. S. Environmental Protection Agency, August 1978.
58. Environmental Assessment Of Coal And Oil Firing In A Controlled Industrial Boiler, Volume III,
EPA-600/7-78-164c, U. S. Environmental Protection Agency, August 1978.
59. Emission Reduction On Two Industrial Boilers With Major Combustion Modifications,
EPA-600/7-78-099a, U. S. Environmental Protection Agency, August 1978.
60. Emission Reduction On Two Industrial Boilers With Major Combustion Modifications, Data
Supplement, EPA-600/7-78-0995, U. S. Environmental Protection Agency, August 1978.
61. Residential Oil Furnace System Optimization, Phase II, EPA-600/2-77-028, U. S. Environmental
Protection Agency, January 1977.
62. Characterization Of Paniculate Emissions From Refinery Process Heaters And Boilers,
API Publication No. 4365, June 1983.
63. Industrial Boilers Emission Test Report, Boston Edison Company, Everett, Massachusetts, EMB
Report 81-IBR-15, U. S. Environmental Protection Agency, Office of Air Quality Planning and
Standards, October 1981.
64. Field Chemical Emissions Monitoring Project: Site 13 Emissions Monitoring, EPRI Project
RP3177-1, Radian Corporation, Austin, Texas, February, 1993.
65. Field Chemical Emissions Monitoring Project, Site 112 Emissions Report, Preliminary Draft,
Carnot, Tustin, California, February 24, 1994. (EPRI Report)
66. Field Chemical Emissions Monitoring Project: Emissions Report For sites 103 - 109, Preliminary
Draft Report, Radian Corporation, Austin, Texas, March 1993. (EPRI Report)
67. Field Chemical Emissions Monitoring Project: Site 118 Emissions Report, Preliminary Draft,
Carnot, Tustin, California, January 20, 1994. (EPRI Report)
68. Emissions Inventory Testing at Long Beach Auxiliary Boiler for Southern California Edison
Company, Carnot, May 1990.
69. Emission Inventory Testing at Alarnitos Unit 5 for Southern California Edison Company, Carnot,
May 1990.
70. Air Toxic emissions Testing at Morro Bay Unit 3 for Pacific Gas and Electric Company, Carnot,
May 1990.
71. Emission Inventory Testing at El Segundo Generating Station 1, for Southern California Edison
Company, Carnot, April 1990.
1.3-34 EMISSION FACTORS 9/98
-------
72. Electric Utility Fuel Oil Fired Electric Utility Boiler Emission Report, for Long Island Lighting
Corporation, Entropy Incorporated, April 1994.
73. Perry, Robert H. and Don Green (1984) Perry's Chemical Engineers'Handbook, Sixth ed., New
York: McGraw Hill.
74. Steam: Its Generation and Use, Babcock and Wilcox, New York, 1975.
75. Compilation of Air Pollutant Emission Factors, Volume I: Stationary Point and Area Sources
(1995) U.S. Environmental Protection Agency, AP-42. Fifth Edition. Research Triangle Park,
NC.
76. Results of the September 14 and 15, 1994 Air Emission Compliance Tests on the No. 11 Boiler at
the Appleton Paper Plant in Combined Locks, Wisconsin. Interpoll Laboratories. October 10,
1994.
77. Compliance Emission Test Report for Lakewood Cogeneration, L.P. Lakewood Township, New
Jersey. Environmental Laboratories, Inc. December 19, 1994.
78. Compliance Test Report Air Emissions from Utility Boilers A, B, and C. Mobile Oil Corporation.
Paulsboro, New Jersey. ENSA Environmental, Inc. May 1995.
79. Boise Cascade Combined Power Boilers Title V Fuel Oil Compliance Test Report. St. Helens,
Oregon Paper Mill. Bighorn Environmental Quality Control. August 8, 1996.
80. Results of the July 13, 1993 Paniculate and Sulfur Dioxide Emission Compliance Testing at the
Land O'Lakes Plant in Spencer, Wisconsin. Interpoll Laboratories, Inc. August 16, 1993.
81. Results of the May 31, 1995 Air Emission Compliance Tests of the No. 1 Boiler at the Land
O'Lakes Plant in Spencer, Wisconsin. Interpoll Laboratories, Inc. July 12, 1995.
82. Boiler Emission Testing at KC-Neenah Paper, Whiting Mill, Stevens Point, WI. Badger
Laboratories and Engineering. February 27, 1995.
83. Emissions Inventory Testing at Long Beach Turbine Combustion Turbine No. 3. CARNOT,
Tustin, CA. May 1989.
84. C.A. Miller. Hazardous Air Pollutants from the Combustion of an Emulsified Heavy Oil in a
Firetube Boiler. EPA-600/R-96-019. U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina. February 1996.
9/98 External Combustion Sources 1.3-35
-------
1.6 Wood Waste Combustion In Boilers
1.6.1 General15
The burning of wood waste in boilers is mostly confined to those industries where it is available
as a byproduct. It is burned both to obtain heat energy and to alleviate possible solid waste disposal
problems. In boilers, wood waste is normally burned in the form of hogged wood, bark, sawdust,
shavings, chips, mill rejects, sanderdust, or wood trim. Heating values for this waste range from about
4,000 to 5,000 British thermal units/pound (Btu/lb) of fuel on a wet, as-fired basis. The moisture content
of as-fired wood is typically near 50 weight percent, but may vary from 5 to 75 weight percent depending
on the waste type and storage operations.
Generally, bark is the major type of waste burned in pulp mills; either a mixture of wood and
bark waste or wood waste alone is burned most frequently in the lumber, furniture, and plywood
industries. As of 1980, there were approximately 1,600 wood-fired boilers operating in the U. S., with a
total capacity of over 1.0 x 10" Btu/hour.
1.6.2 Firing Practices5'7
Various boiler firing configurations are used for burning wood waste. One common type of
boiler used in smaller operations is the Dutch oven. This unit is widely used because it can burn fuels
with very high moisture content. Fuel is fed into the oven through an opening in the top of a
refractory-lined furnace. The fuel accumulates in a cone-shaped pile on a flat or sloping grate.
Combustion is accomplished in two stages: (1) drying and gasification, and (2) combustion of gaseous
products. The first stage takes place in the primary furnace, which is separated from the secondary
furnace chamber by a bridge wall. Combustion is completed in the secondary chamber before gases enter
the boiler section. The large mass of refractory helps to stabilize combustion rates but also causes a slow
response to fluctuating steam demand.
In another boiler type, the fuel cell oven, fuel is dropped onto suspended fixed grates and is fired
in a pile. Unlike the Dutch oven, the refractory-lined fuel cell also uses combustion air preheating and
positioning of secondary and tertiary air injection ports to improve boiler efficiency. Because of their
overall design and operating similarities, however, fuel cell and Dutch oven boilers have comparable
emission characteristics.
The firing method most commonly employed for wood-fired boilers with a steam generation rate
larger than 100,000 Ib/hr is the spreader stoker. In this boiler type, wood enters the furnace through a
fuel chute and is spread either pneumatically or mechanically across the furnace, where small pieces of
the fuel bum while in suspension. Simultaneously, larger pieces of fuel are spread in a thin, even bed on
a stationary or moving grate. The burning is accomplished in three stages in a single chamber:
(1) moisture evaporation; (2) distillation and burning of volatile matter; and (3) burning of fixed carbon.
This type of boiler has a fast response to load changes, has improved combustion control, and can be
operated with multiple fuels. Natural gas, oil, and/or coal, are often fired in spreader stoker boilers as
auxiliary fuels. The fossil fuels are fired to maintain constant steam when the wood waste moisture
content or mass rate fluctuates and/or to provide more steam than can be generated from the waste supply
alone. Although spreader stokers are the most common stokers among larger wood-fired boilers,
overfeed and underfeed stokers are also utilized for smaller units.
2/99 External Combustion Sources 1.6-1
-------
Another boiler type sometimes used for wood combustion is the suspension-fired boiler. This
boiler differs from a spreader stoker in that small-sized fuel (normally less than 2 mm) is blown into the
boiler and combusted by supporting it in air rather than on fixed grates. Rapid changes in combustion
rate and, therefore, steam generation rate are possible because the finely divided fuel particles bum very
quickly.
A recent innovation in wood firing is the fluidized bed combustion (FBC) boiler. A fluidized
bed consists of inert particles through which air is blown so that the bed behaves as a fluid. Wood waste
enters in the space above the bed and burns both in suspension and in the bed. Because of the large
thermal mass represented by the hot inert bed particles, fluidized beds can handle fuels with moisture
contents up to near 70 percent (total basis). Fluidized beds can also handle dirty fuels (up to 30 percent
inert material). Wood fuel is pyrolyzed faster in a fluidized bed than on a grate due to its immediate
contact with hot bed material. As a result, combustion is rapid and results in nearly complete combustion
of the organic matter, thereby minimizing the emissions of unbumed organic compounds.
1.6.3 Emissions And Controls6"11
The major emission of concern from wood boilers is particulate matter (PM), although other
pollutants, particularly carbon monoxide (CO), volatile organic compounds (VOC), and oxides of
nitrogen (NOX) may be emitted in significant quantities when certain types of wood waste are combusted
or when operating conditions are poor. These emissions depend on a number of variables, including
(1) the composition of the waste fuel burned, (2) furnace design and operating conditions, and (3) the
degree of flyash reinjection employed.
1.6.3.1 Criteria Pollutants
The composition of wood waste and the characteristics of the resulting emissions depend largely
on the industry from which the wood waste originates. Pulping operations, for example, produce great
quantities of bark that may contain more than 70 weight percent moisture, sand, and other
non-combustibles. As a result, bark boilers in pulp mills may emit considerable amounts of particulate
matter to the atmosphere unless they are controlled. On the other hand, some operations, such as
furniture manufacturing, generate a clean, dry wood waste (2 to 20 weight percent moisture) which
produces relatively low particulate emission levels when properly burned. Still other operations, such as
sawmills, burn a varying mixture of bark and wood waste that results in PM emissions somewhere
between these two extremes. Additionally, NOX emissions from bark boilers are typically low in
comparison to NOX emissions from sanderdust-fired boilers at urea formaldehyde process particleboard
plants.
Furnace design and operating conditions are particularly important when firing wood waste. For
example, because of the high moisture content that may be present in wood waste, a larger than usual
area of refractory surface is often necessary to dry the fuel before combustion. In addition, sufficient
secondary air must be supplied over the fuel bed to bum the volatiles that account for most of the
combustible material in the waste. When proper drying conditions do not exist, or when secondary
combustion is incomplete, the combustion temperature is lowered, and increased PM, CO, and organic
compound emissions may result. Significant variations in fuel moisture content can cause short-term
emissions to fluctuate.
Flyash reinjection, which is commonly used with larger boilers to improve fuel efficiency, has a
considerable effect on PM emissions. Because a fraction of the collected flyash is reinjected into the
boiler, the dust loading from the furnace and, consequently, from the collection device increase
significantly per unit of wood waste burned. More recent boiler installations typically separate the
collected particulate into large and small fractions in sand classifiers. The larger particles, which are
1.6-2 EMISSION FACTORS 2/99
-------
mostly carbon, are reinjected into the furnace. The smaller particles, mostly inorganic ash and sand, are
sent to ash disposal.
1.6.3.2 Greenhouse Gases12-17
Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions are all produced
during wood waste combustion. Nearly all of the fuel carbon (99 percent) in wood waste is converted to
CO2 during the combustion process. This conversion is relatively independent of firing configuration.
Although the formation of CO acts to reduce CO2 emissions, the amount of CO produced is insignificant
compared to the amount of CO2 produced. The majority of the fuel carbon not converted to CO2 is due to
incomplete combustion and is entrained in the bottom ash. CO2 emitted from this source may not
increase total atmospheric CO2, however, because emissions may be offset by the offtake of CO2 by
regrowing biomass.
Formation of N2O during the combustion process is governed by a complex series of reactions
and its formation is dependent upon many factors. Formation of N2O is minimized when combustion
temperatures are kept high (above 1475°F) and excess air is kept to a minimum (less than 1 percent).
N2O emissions for wood waste combustion are not significant except for fluidized bed combustion
(FBC), where localized areas of lower temperatures in the fuel bed produce N2O emissions an order of
magnitude greater than emissions from stokers.
Methane emissions are highest during periods of low-temperature combustion or incomplete
combustion, such as the start-up or shut-down cycle for boilers. Typically, conditions that favor
formation of N2O also favor emissions of CH4.
1.6.4 Controls
Currently, the four most common control devices used to reduce PM emissions from wood-fired
boilers are mechanical collectors, wet scrubbers, electrostatic precipitators (ESPs), and fabric filters. The
use of multitube cyclone (or multiclone) mechanical collectors provides paniculate control for many
fuel-fired boilers. Often, two multiclones are used in series, allowing the first collector to remove the
bulk of the dust and the second to remove smaller particles. The efficiency of this arrangement varies
from 65 to 95 percent. The most widely used wet scrubbers for wood-fired boilers are venturi scrubbers.
With gas-side pressure drops exceeding 15 inches of water, paniculate collection efficiencies of
90 percent or greater have been reported for venturi scrubbers operating on wood-fired boilers.
Fabric filters (i. e., baghouses) and ESPs are employed when collection efficiencies above
95 percent are required. When applied to wood-fired boilers, ESPs are often used downstream of
mechanical collector precleaners which remove larger-sized particles. Collection efficiencies of 93 to
99.8 percent for PM have been observed for ESPs operating on wood-fired boilers.
A variation of the ESP is the electrostatic gravel bed filter. In this device, PM in flue gases is
removed by impaction with gravel media inside a packed bed; collection is augmented by an electrically
charged grid within the bed. Paniculate collection efficiencies are typically near 95 percent.
Fabric filters have had limited applications to wood-fired boilers. The principal drawback to
fabric filtration, as perceived by potential users, is a fire danger arising from the collection of
combustible carbonaceous fly ash. Steps can be taken to reduce this hazard, including the installation of
a mechanical collector upstream of the fabric filter to remove large burning particles of fly ash (i. e.,
"sparklers"). Despite complications, fabric filters are generally preferred for boilers firing salt-laden
wood. This fuel produces fine particulates with a high salt content. Fabric filters are capable of high
fine particle collection efficiencies; in addition, the salt content of the particles has a quenching effect,
2/99 External Combustion Sources 1.6-3
-------
thereby reducing fire hazards. In two tests of fabric filters operating on salt-laden wood-fired boilers,
participate collection efficiencies were above 98 percent.
For stoker and FBC boilers, overfire air ports may be used to lower NOX emissions by staging the
combustion process. In those areas of the U. S. where NOX emissions must be reduced to their lowest
levels, the application of selective noncatalytic reduction (SNCR) to waste wood-fired boilers has been
accomplished; the application of selective catalytic reduction (SCR) is being contemplated. Both
systems are postcombustion NOX reduction techniques in which ammonia (or urea) is injected into the
flue gas to selectively reduce NOX to nitrogen and water. In one application of SNCR to an industrial
wood-fired boiler, NOX reduction efficiencies varied between 35 and 75 percent as the ammonia-to-NOx
ratio increased from 0.4 to 3.2.
Emission factors and emission factor ratings for wood waste boilers are summarized in
Tables 1.6-1,1.6-2, 1.6-3, 1.6-4, and 1.6-5.18"19 Tables in this section present emission factors on a
weight basis (Ib/ton). To convert to an energy basis (Ib/MMBtu), divide by a heating value of
9.0 MMBtu/ton. Emission factors are for uncontrolled combustors unless otherwise indicated.
Cumulative particle size distribution data and associated emission factors are presented in Tables 1.6-6
and 1.6-7. Uncontrolled and controlled size-specific emission factors are plotted in Figure 1.6-1 and
Figure 1.6-2. All emission factors presented are based on the feed rate of wet, as-fired wood with
average properties of 50 weight percent moisture and 4500 Btu/lb higher heating values.
1.6.5 Updates Since the Fifth Edition
The Fifth Edition was released in January 1995. Revisions to this section since that date are
summarized below. For further detail, consult the memoranda describing each supplement or the
background report for this section. These and other documents can be found on the CHIEF electronic
bulletin board (919-541-5742), or on the new EFIG home page (http://www.epa.gov/oar/oaqps/efig/).
Supplement A, February 1996
• Significant figures were added to some PM and PM-10 emission factors.
• In the table with NOX and CO emission factors, text was added in the footnotes to clarify
meaning.
Supplement B, October 1996
• SOX, CH,, N2O, CO2, speciated organics, and trace elements emission factors were
corrected.
• Several HAP emission factors were updated.
Supplement D, February 1998
• Table 1.6-1, the PM-10 and one PM emission factors were revised to present two
significant figures and the PM-10 emission factor for wood-fired boilers with mechanical
collectors without flyash reinjection was revised to 2.6 Ib/ton to reflect that these values
are based on wood with 50% moisture. A typographical error in the wet scrubber
emission factor for PM-10 was corrected.
1.6-4 EMISSION FACTORS 2/99
-------
Table 1.6-2, the SOA emission factors for all boiler categories were revised to
0.075 Ib/ton to reflect that these factors are based on wood with 50% moisture.
Tables 1.6-4 and 1.6-5 were re-titled to reflect that the speciated organic and trace
element analysis presented in these tables are compiled from wood-fired boilers
equipped with a variety of PM control technologies.
Supplement D, August 1998
Table 1.6-4, the emission factor for trichlorotrifluoroethane was removed. The phenol
emission factor was corrected to 1.47E-04; the phenanthrene factor was corrected to
5.02E-05; the chrysene factor was corrected to 4.52E-07; and, the polychlorinated
dibenzo-p-furans factor was corrected to 2.9E-08.
Supplement E, February 1999
In the footnotes of tables 1.6-1, 2, 3, 4, 5, 6, 7, some text was removed that described
how to adjust the factors when burning wood with moisture and thermal content
significantly different from 50% or 4500 Btu/lb, respectively. The EPA is revising
Section 1.6 and, in the interim, consistent with EPA's recommendations regarding proper
use of AP-42, the EPA encourages users of the wood combustion emission factors to
account for the specific assumptions included in the factors and to convert the factors to
a thermal content basis (i.e., Ib/MMBtu) to estimate emissions when burning wood that
differs significantly from 4500 Btu/lb or 50% moisture.
1/99 External Combustion Sources 1.6-5
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2/99
-------
Table 1.6-4. EMISSION FACTORS FOR SPECIATED ORGANIC COMPOUNDS FROM WOOD
WASTE COMBUSTION WITH PM CONTROLS8
Organic Compound11
Phenols™
Acenaphthene41
Fluorene1"
Phenanthrenedd
Anthracene
Fluoranthenedd
Benzo(a)anthracenedd
Benzo(k)fluoranthenedd
Benzo(b+k)fluoranthenedd
Benzofl uoranthene sdd
Benzo(a)pyrenedd
Benzo(g,h,i)perylenedd
Chrysenedd
Indeno( 1 ,2,3,c,d)pyrenedd
Polychlorinated dibenzo-p-dioxins
Polychlorinated dibenzo-p-furans
Acenaphthylenedd
Methyl anthracene1"
Acroleindd
Solicyladehyde
Benzaldehyde
Formaldehyde'"
Acetaldehyde1"
Benzenedd
Naphthalene"
2,3J,8-Tetrachlorodibenzo-p-dioxindd
2-Chlorophenoldd
2,4-Dimtrophenoldd
Methane
4-Nitrophenoldd
Pyrene
Average Emission Factor
(Ib/ton)
1.47E-04C
4.10E-06d
8.22 E-06e
5.02 E-05C
3.3 E-06f
1.83 E-058
3.27 E-06"
7.65 E-07J
2.9 E-05k
1.08E-06""1
6.75 E-OS"1"
\AlE-0(f
4.52 E-071
3.6 E-07r
1.2E-08k'sl
2.9E-08kAU
4.76 E-05"
1.4E-04m
4.0 E-06m
2.3 E-05m
1.2E-05m
8.2 E-03W
1.92E-03"
9.95 E-03X
3.39 E-03y
3.6E-llk
5.13E-071"-11
4.23 E-Oe™
1.12E-022
2.97 E-06m
1.67 E-051*
EMISSION FACTOR RATING
C
C
C
B
C
B
C
E
C
E
E
D
C
D
C
C
B
D
D
D
D
B
B
B
C
D
E
E
D
E
B
Units are Ib of pollutant/ton of wood waste burned. To convert from Ib/ton to kg/Mg, multiply by 0.5. To
convert from Ib/ton to Ib/MMBtu, multiply by 0.11. Emission factors are based on wet, as-fired wood waste
with average properties of 50 weight % moisture and 4500 Btu/lb higher heating value. Source Classification
Codes are 1-01-009-01/02/03,1-02-009-01/01/03/04/05/06/07, and 1-03-009-01/02/03.
Pollutants in this table represent organic species measured for wood waste combustors equipped with PM
controls (i.e., fabric filters, multi-cyclones, ESP, and wet scrubbers). Other organic species may
also have been emitted but either were not measured or were present at concentrations below analytical limits.
References 32-35.
References 34-39.
References 34-41.
References 34-39,41.
References 32-41.
References 34,37,39,40.
1199
External Combustion Sources
1.6-9
-------
Table 1.6-4 (cont.)-
1 References 34,36.
k References 11,19-23,26,31,42.
m Based on data from one source test,
11 Reference 35.
p References 35-36,39.
q References 34-35,39-40.
' References 35,39.
* Emission factors are for total dioxins and furans, not toxic equivalents.
' Excludes data from combustion of salt-laden wood. For salt-laden wood, emission factor is 1.3 E-06 Ib/ton with
a D rating.
" Excludes data from combustion of salt-laden wood. For salt-laden wood, emission factor is 5.5 E-07 Ib/ton with
a D rating.
v References 32,34-40.
w References 32-41,43.
x References 32-40,43.
y References 32-34,37,40-41.
z Reference 44.
M References 34,36-38.
** References 32,34-36,37-41.
"* Emission factor value includes phenol, which is a hazardous air pollutant (HAP), plus substituted phenols which are not
** Hazardous air pollutant.
1.6-10 EMISSION FACTORS 2/99
-------
Table 1.6-5. EMISSION FACTORS FOR TRACE ELEMENTS
FROM WOOD WASTE COMBUSTION WITH PM CONTROLS3
Trace Element6
Chromium (VI)
Copper
Zinc
Barium
Potassium
Sodium
Iron
Lithium
Boron
Chlorine
Vanadium
Cobalt
Thorium
Tungsten
Dysprosium
Samarium
Neodymium
Praseodymium
Iodine
Tin
Molybdenum
Niobium
Zirconium
Yttrium
Rubidium
Bromine
Germanium
Arsenic
Cadmium
Chromium (Total)
Lead
Manganese
Mercury
Nickel
Selenium
Average Emission Factor (Ib/ton)
4.6 E-05C
3.73 E-04"
2.51 E-03d
4.4 E-03'
7.8 E-01e
1.8E-02'
4.4 E-02'
7.0 E-05'
8.0 E-04'
7.8 E-03e
.2 E-04e
.3 E-04e
.7 E-05'
.1 E-05e
.3 E-05e
2.0 E-05C
2.6 E-05'
3.0 E-05'
1.8E-05*
3.1 E-05*
1.9E-04e
3.5 E-05e
3.5 E-04C
5.6 E-05'
1.2E-03'
3.9 E-04*
2.5 E-06e
8.53 E-05f
2.12E-05f
1.56E-04"
4.45 E-04d
1.26E-02r
5.15 E-06h
6.90 E-05J
4.59 E-05ei
EMISSION FACTOR RATING
D
B
B
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
B
B
B
B
B
C
B
E
* Units are Ib of pollutant/ton of wood waste burned. To convert from Ib/ton to kg/Mg, multiply by 0.5. To
convert from Ib/ton to Ib/MMBtu, multiply by 0.11. Emission factors are based on wet, as-fired wood waste with
average properties of 50 weight % moisture and 4500 Btu/lb higher heating value. Source Classification Codes
are 1-010-09-01/02/03, 1-02-009-01/02/03/04/05/06/07, and 1-03-009-01/02/03.
b Pollutants in this table represent metal species measured for wood waste combustors equipped with PM controls
(i.e., fabric filters, multi-cyclones, ESP, and wet scrubbers). Other metal species may also have been emitted but
were either not measured or were present at concentrations below analytical limits.
c References 11,19-22.
" References 32,34-41.
e Based on data from one source test.
f References 32,34-37,39,41.
8 References 32,34-39,41.
" References 32,34-35,37.
1 References 32,34-37,40.
k References 40.
2/99
External Combustion Sources
1.6-11
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External Combustion Sources
1.6-15
-------
References For Section 1.6
1. Emission Factor Documentation For AP-42 Section 1.6 Wood Waste Combustion In Boilers ,
Technical Support Division, Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC, April 1993.
2. Steam, 38th Edition, Babcock and Wilcox, New York, NY, 1972.
3. Atmospheric Emissions From The Pulp And Paper Manufacturing Industry, EPA-450/1-73-002,
U. S. Environmental Protection Agency, Research Triangle Park, NC, September 1973.
4. C-E Bark Burning Boilers, C-E Industrial Boiler Operations, Combustion Engineering, Inc.,
Windsor, CT, 1973.
5. Nonfossil Fuel Fired Industrial Boilers Background Information , EPA-450/3-82-007, U. S.
Environmental Protection Agency, Research Triangle Park, NC, March 1982.
6. Control Of Paniculate Emissions From Wood-Fired Boilers , EPA 340/1 -77-026, U.S.
Environmental Protection Agency, Washington, DC, 1977.
7. Background Information Document For Industrial Boilers, EPA 450/3-82-006a, U. S.
Environmental Protection Agency, Research Triangle Park, NC, March 1982.
8. E. F. Aul, Jr. and K. W. Barnett, "Emission Control Technologies For Wood-Fired Boilers",
Presented at the Wood Energy Conference, Raleigh, NC, October 1984.
9. G. Moilanen, et al., "Noncatalytic Ammonia Injection For NOX Reduction on a Waste Wood
Fired Boiler", Presented at the 80th Annual Meeting of the Air Pollution Control Association,
New York, NY, June 1987.
10. "Information On The Sulfur Content Of Bark And Its Contribution To SO2 Emissions When
Burned As A Fuel", H. Oglesby and R. Blosser, Journal Of The Air Pollution Control Agency,
30(7):769-772, July 1980.
11. Written communication from G. Murray, California Forestry Association, Sacramento, CA to E.
Aul, Edward Aul & Associates, Inc., Chapel Hill, NC, Transmittal of Wood Fired Boiler
Emission Test, April, 24, 1992.
12. L. P. Nelson, L. M. Russell, and J. J. Watson, "Global Combustion Sources of Nitrous Oxide
Emissions", Research Project 2333-4 Interim Report, Radian Corporation, Sacramento, CA,
1991.
13. Rebecca L. Peer, Eric P. Epner, and Richard S. Billings, Characterization Of Nitrous Oxide
Emission Sources, EPA Contract No. 68-D1-0031, Research Triangle Park, NC, 1995.
14. Steven D. Piccot, Jennifer A. Buzun, and H. Christopher Frey, Emissions And Cost Estimates
For Globally Significant Anthropogenic Combustion Sources OfNOv N2O, CH4, CO, And CO2,
EPA Contract No. 68-02-4288, Research Triangle Park, NC, 1990.
1.6-16 EMISSION FACTORS 2/99
-------
15. G. Marland, and R. M. Rotty, Carbon Dioxide Emissions From Fossil Fuels: A Procedure For
Estimation And Results For 1951-1981, DOE/NBB-0036 TR-003, Carbon Dioxide Research
Division, Office of Energy Research, U.S. Department of Energy, Oak Ridge, TN, 1983.
16. Sector-Specific Issues And Reporting Methodologies Supporting The General Guidelines For
The Voluntary Reporting Of Greenhouse Gases Under Section I605(b) Of The Energy Policy Act
Of 1992, Volume 2 of 3, U.S. Department of Energy, DOE/PO-0028, 1994.
17. R. A. Kester, Nitrogen Oxide Emissions From A Pilot Plant Spreader Stoker Bark Fired Boiler ,
Department of Civil Engineering, University of Washington, Seattle, WA, December 1979.
18. A. Nunn, NO, Emission Factors For Wood Fired Boilers, EPA-600/7-79-219, U. S.
Environmental Protection Agency, September 1979.
19. Hazardous Air Emissions Potential From A Wood-Fired Furnace (and Attachments) ,
A. J. Hubbard, Wisconsin Department of Natural Resources, Madison, WI, July 1991.
20. Environmental Assessment Of A Wood-Waste-Fired Industrial Watertube Boiler , EPA Contract
No. 68-02-3188, Acurex Corporation, Mountain View, CA, March 1984.
21. Evaluation Test On A Wood Waste Fired Incinerator At Pacific Oroville Power Inc. , Test Report
No. C-88-050, California Air Resources Board, Sacramento, CA, May 1990.
22. Evaluation Test On Twin Fluidized Bed Wood Waste Fueled Combustors Located In Central
California, Test Report No. C-87-042, California Air Resources Board, Sacramento, CA,
February, 1990.
23. A Polycyclic Organic Materials Study For Industrial Wood-Fired Boilers , Technical Bulletin
No. 400, National Council of the Paper Industry For Air and Stream Improvement, New York,
NY, May 1983.
24. Compilation Of Air Pollutant Emission Factors, Supplement A , Section 1.6, U. S. Environmental
Protection Agency, Research Triangle Park, NC, 1986.
25. Emission Test Report, Owens-Illinois Forest Products Division, Big Island, Virginia , EMB
Report 80-WFB-2, U. S. Environmental Protection Agency, Research Triangle Park, NC,
February 1980.
26. National Dioxin Study Tier 4, Combustion Sources: Final Test Report, Site 7, Wood Fired Boiler
WFB-A, EPA-450/4-84-014p, U. S. Environmental Protection Agency, Research Triangle Park,
NC, April 1987.
27. A Study Of Nitrogen Oxides Emissions From Wood Residue Boilers, Technical Bulletin No. 102,
National Council of the Paper Industry for Air and Stream Improvement, New York, NY,
November 1979.
28. H. S. Oglesby and R. O. Blosser, "Information On The Sulfur Content Of Bark And Its
Contribution To SO2 Emissions When Burned As A Fuel", Journal Of The Air Pollution Control
Agency, 30(7):769-772, July 1980.
2/99 External Combustion Sources 1.6-17
-------
29. Carbon Monoxide Emissions From Selected Combustion Sources Based On Short-Term
Monitoring Records, Technical Bulletin No. 416, National Council of the Paper Industry For Air
and Stream Improvement, New York, NY, January 1984.
30. Volatile Organic Carbon Emissions From Wood Residue Fired Power Boilers In The Southeast,
Technical Bulletin No. 455, National Council of the Paper Industry For Air and Stream
Improvement, New York, NY, April 1985.
31. A Study Of Formaldehyde Emissions From Wood Residue-Fired Boilers, Technical Bulletin
No. 622, National Council of the Paper Industry For Air and Stream Improvement, New York,
NY, January 1992.
32. Source Emission Testing of the Wood-Fired Boiler Exhaust at Sierra Pacific, Burney, California,
Performed for the Timber Association of California, Galston Technical Services, February 1991.
33. Source Emission Testing of the Wood-fired Boiler #1 Exhaust Stack at Wheelabrator Shasta
Energy Company (TAG Site 9), Anderson, California, Performed for the Timber Association of
California, Galston Technical Services, January 1991.
34. Source Emission Testing of the Wood-fired boiler at Catalyst Hudson, Inc., Anderson California,
Performed for the Timber Association of California, Galston Technical Services, February 1991.
35. Source Emission Testing of the Wood-fired Boiler at Big Valley Timber Company, Bieber,
California, Performed for the Timber Association of California, Galston Technical Services,
February, 1991.
36. Source Emission Testing of the CE Wood-Fired Boiler at Roseburg Forest Products (TAG Site
#3), Performed for the Timber Association of California, Galston Technical Services, January
1991.
37. Source Emission Testing of the Wood-fired Boiler #3 Exhaust at Georgia Pacific, Fort Bragg,
California, Performed for the Timber Association of California, Galston Technical Services,
February 1991.
38. Source Emission Testing of the Wood-fired Boiler "C" Exhaust at Pacific Timber, Scotia,
California, Performed for the Timber Association of California, Galston Technical Services,
February 1991.
39. Source Emission Testing of the Wood-fired Boiler Exhaust at Bohemia, Inc., Rocklin, California,
Prepared for the Timber Association of California, Galston Technical Services, December 1990.
40. Source Emission Testing of the Wood-fired Boiler at Yanke Energy, North Fork, California,
Performed for the Timber Association of California, Galston Technical Services, January 1991.
41. Source Emission Testing of the Wood-fired Boiler Exhaust at Miller Redwood Co., Crescent
City, California, Performed for the Timber Association of California, Galston Technical
Services, February 1991.
42. Emission Test Report, St. Joe Paper Company, Port St. Joe, Florida, EMB Report 80-WFB-5, U.
S. Environmental Protection Agency, Research Triangle Park, NC, May 1980.
1.6-18 EMISSION FACTORS 2/99
-------
43. Source Emission Testing of the Wood-fired Boiler #5 Exhaust at Roseburg Forest Products,
Anderson, California, Performed for the Timber Association of California, Galston Technical
Services, January 1991.
44. Nation Council Of The Paper Industry For Air And Stream Improvement, An Air Emission
Database for Wood Product Plant Combustion Units, Technical Bulletin No. 695. April 1995.
45. Inhalable Paniculate Source Category Report For External Combustion Sources , EPA Contract
No. 68-02-3156, Acurex Corporation, Mountain View, CA, January 1985.
2/99 External Combustion Sources 1.6-19
-------
1.7 Lignite Combustion
1.7.1 General1'5
Coal is a complex combination of organic matter and inorganic ash formed over eons from
successive layers of fallen vegetation. Coals are classified by rank according to their progressive
alteration in the natural metamorphosis from lignite to anthracite. Coal rank depends on the volatile
matter, fixed carbon, inherent moisture, and oxygen, although no one parameter defines rank. Typically
coal rank increases as the amount of fixed carbon increases and the amount of volatile matter decreases.
Lignite is a coal in the early stages of coalification, with properties intermediate to those of
bituminous coal and peat. The two geographical areas of the U. S. with extensive lignite deposits are
centered in the States of North Dakota and Texas. The lignite in both areas has a high moisture content
(20 to 40 weight percent) and a low heating value (5,000 to 7,500 British thermal units per pound
[Btu/lb], on a wet basis). Due to high moisture content and low Btu value, shipping the lignite would not
be feasible; consequently, lignite is burned near where it is mined. A small amount is used in industrial
and domestic situations, but lignite is mainly used for steam/electric production in power plants. Lignite
combustion has advanced from small stokers to large pulverized coal (PC) and cyclone-fired units
(greater than 500 megawatt).
The major advantages of firing lignite are that it is relatively abundant (in the North Dakota and
Texas regions), relatively low in cost since it is surface mined, and low in sulfur content which can
reduce the need for postcombustion sulfur emission control devices. The disadvantages are that more
fuel and larger, more capital-intensive facilities are necessary to generate a unit of power with lignite
than is the case with bituminous coal. The disadvantages arise because: (1) lignite's lower heating value
means more fuel must be handled to produce a given amount of power; (2) the energy and maintenance
costs of coal handling equipment are higher; (3) the high inherent moisture content of lignite decreases
boiler efficiency; and (4) the ash characteristics of lignite require more attention to sootblowing and
boiler operation to maintain high availability and reliability.
1.7.2 Firing Practices3
In a pulverized lignite-fired boiler, the fuel is fed from the stock pile into bunkers adjacent to the
boiler. From there, the fuel is metered into several pulverizers which grind it to approximately 200-mesh
particle size. A stream of hot air from the air preheater begins the fuel-drying process and conveys the
fuel pneumatically to the burner nozzle where it is injected into the burner zone of the boiler. Firing
configurations of boilers that fire pulverized lignite include tangential, horizontally opposed, front wall,
cyclone, stoker, and fluidized bed combustor.
In the tangential firing method, the pulverized lignite is introduced from the comers of the boiler
in vertical rows of burner nozzles. Such a firing mechanism produces a vortexing flame pattern which
essentially uses the entire furnace enclosure as a burner. In front-wall firing and horizontally opposed
firing boilers, the pulverized coal is introduced into the burner zone through a horizontal row of burners.
This type of firing mechanism produces a more intense combustion pattern than the tangential design and
has a slightly higher heat release rate in the burner zone itself.
In these methods of firing pulverized lignite, the ash is removed from the furnace both as fly ash
and bottom ash. The bottom of the furnace is often characterized as either wet or dry, depending on
9/98 External Combustion Sources 1.7-1
-------
whether the ash is removed as a liquid slag or as a solid. Pulverized coal units have been designed for
both wet and dry bottoms, but the current practice is to design only dry bottom furnaces.
Another type of boiler firing lignite is the cyclone burner, which is a slag-lined high-temperature
vortex burner. The coal is fed from the storage area to a crusher that reduces the lignite into particles of
approximately 0.25 inch in diameter or less. Crushed lignite is partially dried in the crusher and is then
fired in a tangential or vortex pattern into the cyclone burner. The temperature within the burner is hot
enough to melt the ash to form a slag. Centrifugal force from the vortex flow forces the melted slag to
the outside of the burner where it coats the burner walls with a thin layer of slag. As the solid lignite
particles are fed into the burner, they are forced to the outside of the burner and are imbedded in the slag
layer. The solid lignite particles are trapped there until complete burnout is attained. The ash from the
burner is continuously removed through a slag tap which is flush with the furnace floor.
In a stoker furnace, the lignite is spread across a grate to form a bed which burns until the lignite
is completely burned out. In such a mechanism, the lignite is broken up into approximately 2-inch pieces
and is fed into the furnace by one of several feed mechanisms: underfeed, overfeed, or spreading. In
most stoker units, the grate on which the lignite is burned gradually moves from one end of the furnace to
the other. The lignite is spread on the grate in such a fashion that at the end of the grate only ash remains
(i.e., all of the lignite has been burned to the final ash product). When the ash reaches the end of the
grate, it falls into an ash collection hopper and is removed from the furnace. Stoker furnaces are
dry-bottom furnaces and, as such, generally have lower heat release rates and lower temperature profiles
than the corresponding pulverized or cyclone units.
There are two major categories of fluidized bed combustors (FBCs): (1) atmospheric FBCs,
operating at or near ambient pressures, and (2) pressurized FBCs, operating between 4 and
30 atmospheres (60 to 450 pounds per square inch gauge). Pressurized FBC systems are not considered a
demonstrated technology for lignite combustion. The two principal types of atmospheric FBCs are
bubbling bed and circulating bed. The fundamental distinguishing feature between these types is the
fluidization velocity, hi the bubbling bed design, the fluidization velocity is relatively low, in order to
minimize solids carryover or elutriation from the combustor. Circulating FBCs, however, employ high
fluidization velocities to promote the carryover or circulation of the solids. High temperature cyclones
are used in circulating bed FBCs and in some bubbling bed FBCs to capture the unbumed solid fuel and
bed material for return to the primary combustion chamber for more efficient fuel utilization.
1.7.3 Emissions2^'6-13
The emissions generated from firing lignite, as with any coal, include the criteria pollutants
paniculate matter (PM), PM less than, or equal to, 10 micrometers in diameter (PM-10), condensable
paniculate matter (CPM), sulfur oxides (SOJ, nitrogen oxides (NOJ, carbon monoxide (CO), and total
organic compounds (TOC). The other pollutants generated include greenhouse gases, organics, trace
elements, and acid gases.
Paniculate Matter Emissions -
Emission levels for PM from lignite combustion are directly related to the ash content of the
lignite and the firing configuration of the boiler. Pulverized coal-fired units fire much or all of the lignite
in suspension. Cyclone furnaces collect much of the ash as molten slag in the furnace itself. Stokers
(other than spreader) retain a large fraction of the ash in the fuel bed and bottom ash. Spreader stokers
fire about 15 percent of the coal in suspension and the remainder in a bed.
Paniculate emissions may be categorized as either filterable or condensable. Filterable emissions
are generally considered to be the particules that are trapped by the glass fiber filter in the front half of a
1.7-2 EMISSION FACTORS 9/98
-------
Reference Method 5 or Method 17 sampling train. Vapors and particles less than 0.3 microns pass
through the filter. Condensable particulate matter is material that is emitted in the vapor state which later
condenses to form homogeneous and/or heterogeneous aerosal particles. The condensable particulate
emitted from boilers fueled on coal or oil is primarily inorganic in nature.
Sulfur Oxides Emissions -
The SOX emissions from lignite combustion are a function of the sulfur content of the lignite and
the lignite composition (i.e., sulfur content, heating value, and alkali concentration). The conversion of
lignite sulfur to SOX is generally inversely proportional to the concentration of alkali constituents in the
lignite. The alkali content is known to have a great effect on sulfur conversion and acts as a built-in
sorbent for SOX removal.
Nitrogen Oxides Emissions -
The NOX emissions from lignite combustion are mainly a function of the boiler design, firing
configuration, and excess air level. Tangential units, stoker boilers, and FBCs typically produce lower
NOX levels than wall-fired units and cyclones. The boilers constructed since implementation of the 1971
and 1979 New Source Performance Standards (40 Code of Federal Regulations, Part 60, Subparts D and
Da, respectively) have NOX controls integrated into the boiler design and have NOX emission levels that
are comparable to emission levels from small stokers. In most boilers, regardless of firing configuration,
lower excess combustion air results in lower NOX emissions. However, lowering the amount of excess
air in a lignite-fired boiler can also affect the potential for ash fouling.
Carbon Monoxide Emissions14 -
The CO emission rate from combustion sources depends on the oxidation efficiency of the fuel.
By controlling the combustion process carefully, CO emissions can be minimized. Thus, if a unit is
operated improperly or not maintained, the resulting concentrations of CO (as well as organic
compounds) may increase by several orders of magnitude.
Greenhouse Gases 15~20 -
Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions are all produced
during lignite combustion. Nearly all of the fuel carbon (99 percent) in lignite is converted to CO2 during
the combustion process. This conversion is relatively independent of firing configuration. Although the
formation of CO acts to reduce CO2 emissions, the amount of CO produced is insignificant compared to
the amount of CO2 produced. The majority of the fuel carbon not converted to CO2 is due to incomplete
combustion and is entrained in the bottom ash.
Formation of N2O during the combustion process is governed by a complex series of reactions
and its formation is dependent upon many factors. Formation of N2O is minimized when combustion
temperatures are kept high (above 1475°F) and excess air is kept to a minimum (less than 1 percent).
N2O emissions for lignite combustion are not significant except for fluidized bed combustion, where
localized areas of lower temperatures in the fuel bed produce N2O emissions significantly higher than
emissions from stokers.
Methane emissions vary with the type of coal being fired and firing configuration, but are highest
during periods of incomplete combustion, such as the start-up or shut-down cycle for coal-fired boilers.
Typically, conditions that favor formation of N2O also favor emissions of CH4.
Organic Compounds -
Trace amounts of organic compounds are emitted during lignite combustion. As with CO
emissions, the rate at which organic compounds are emitted depends on the combustion efficiency of the
9/98 External Combustion Sources 1.7-3
-------
boiler. Therefore, combustion modifications that change combustion residence time, temperature, or
turbulence may increase concentrations of organic compounds in the flue gas.
Organic emissions include volatile, semivolatile, and condensable organic compounds either
present in the lignite or formed as a product of incomplete combustion (PIC). Organic emissions are
primarily characterized by the criteria pollutant class of unbumed vapor-phase hydrocarbons. These
emissions include alkanes, alkenes, aldehydes, alcohols, and substituted benzenes (e.g., benzene, toluene,
xylene, and ethyl benzene).
Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) are formed
during the combustion of lignite. Of primary interest environmentally are tetrachloro- through
octachloro- dioxins and furans. Dioxin and furan emissions are influenced by the extent of destruction of
organics during combustion and through reactions in the air pollution control equipment. The formation
of PCDD/PCDF in air pollution control equipment is primarily dependent on flue gas temperature, with
maximum potential for formation occurring at flue gas temperatures of 450 degrees to 650 degrees
Fahrenheit.
The remaining organic emissions are composed largely of compounds emitted from combustion
sources in a condensed phase. These compounds can almost exclusively be classed into a group known
as polycyclic organic matter (POM), and a subset of compounds called polynuclear aromatic
hydrocarbons (PNA or PAH).
Trace Metals-
Trace metals are also emitted during lignite combustion. The quantity of any given metal
emitted, in general, depends on:
the physical and chemical properties of the metal itself;
the concentration of the metal in the lignite;
the combustion conditions; and
the type of paniculate control device used, and its collection efficiency as a function of
particle size.
Acid Gases-
In addition to SOX and NO, emissions, combustion of lignite also results in emissions of chlorine
and fluorine, primarily in the form of hydrogen chloride (HC1) and hydrogen fluoride (HF). Lesser
amounts of chlorine gas and fluorine gas are also emitted. A portion of the chlorine and fluorine in the
fuel may be absorbed onto fly ash or bottom ash. Both HC1 and HF are water soluble and are readily
controlled by acid gas scrubbing systems.
1.7.4 Controls2"4-6-13
Particulate Matter -
The primary PM control systems for lignite-fired utility boilers are electrostatic precipitators
(ESPs) and fabric filters (baghouses) with collection efficiencies as high as 99.5 percent. Older and
smaller ESPs can have lower collection efficiencies of approximately 95 percent for total PM. Multiple
cyclone collectors and scrubbers are typically used alone, or in series, with an ESP or baghouse on small
industrial stoker boilers and normally achieve 60 to 80 percent collection efficiency for total PM.
1.7-4 EMISSION FACTORS 9/98
-------
Sulfur Oxides14 -
Table 1.7-2 presents the techniques most frequently used to reduce SOX emissions from coal
combustion. Flue gas desulfurization (FGD) systems are in current operation on several lignite-fired
utility boilers. Flue gases can be treated through wet, semi-dry, 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 commonly
applied. Wet systems generally use alkali slurries as the SOX absorbent medium and can be designed to
remove in excess of 90 percent of the incoming SOX. Lime/limestone scrubbers, sodium scrubbers, spray
drying, and dual alkali scrubbing are among the commercially proven FGD techniques.
Spray drying is a dry scrubbing approach in which a solution or slurry of alkaline material is
sprayed into a reaction vessel as a fine mist and mixes with the flue gas. The SO2 reacts with the alkali
solution or slurry to form liquid-phase salts. The slurry is dried by the latent heat of the flue gas to about
1 percent free moisture. The dried alkali continues to react with SO2 in the flue gas to form sulfite and
sulfate salts. The spray dryer solids are entrained in the flue gas and carried out of the dryer to a
particulate control device such as an ESP or baghouse.
Limestone may also be injected into the furnace, typically in an FBC, to react with sulfur dioxide
(SO2) and form calcium sulfate. An FBC is composed of a bed of inert material that is suspended or
"fluidized" by a stream of air. Lignite is injected into this bed and burned. Limestone is also injected
into this bed where it is calcined to lime and reacts with SO2 to form calcium sulfate. Particulate matter
emitted from the boiler is generally captured in a cyclone and recirculated or sent to disposal. Additional
PM control equipment, such as an ESP or baghouse, is used after the cyclone to further reduce particulate
emissions.
Nitrogen Oxides21 -
The most common NOX control technique for lignite-fired boilers is overfire air (OFA) which
involves diverting a portion of the total combustion air (5 to 20 percent) from the burners and injecting it
through dedicated air ports above the top level of burners. OFA can be applied to tangential-fired,
wall-fired, and stoker boilers; however, it cannot be used on cyclone boilers or other slag-tapping
furnaces because it can alter the heat release profile of the boiler which can change the slagging
characteristics of the boiler. Depending on the design of the existing furnace, OFA can be a retrofit
technology that may achieve 20 to 30 percent NOX reduction from uncontrolled levels. It is a typical NOX
control technique used in new Subpart D and Subpart Da boilers.
Another NOX control technique used on lignite-fired boilers is low NOX burners (LNB) which
limit NOX formation by controlling both the stoichiometric and temperature profiles of the combustion
process. LNBs can be retrofit in existing tangential- and wall-fired boilers or installed in new boilers;
however, they are not applicable to cyclone boilers since the fuel is fired in cylindrical chambers in the
cyclone boiler rather than with conventional burners. Depending on boiler design and the desired NOX
level, OFA and LNB can be applied separately, or in combination, to achieve as much as 50-60 percent
reduction from uncontrolled levels.
1.7.5 Emission Factors
Uncontrolled emission factors for SOX, NOX, CO, CO2, and total non-methane organic
compounds (TNMOC) are presented in Table 1.7-1. Controlled emission factors for NOxand CO in
Table 1.7-3.
Table 1.7-4 presents uncontrolled emission factors for filterable PM and N2O, and controlled
emission factors for filterable PM are shown in Table 1.7-5. Condensable PM emission factors are
9/98 External Combustion Sources 1.7-5
-------
presented in Table 1.7-6. Cumulative particle size distributions and particle size-specific emission
factors are provided in Tables 1.7-7 and 1.7-8. In addition, particle size-specific emission factors are
presented graphically in Figures 1.7-1 and 1.7-2.
Tables 1.7-9 through 1.7-11 present emission factors for polynuclear organic matter (POM),
polynuclear aromatic hydrocarbons (PAH), and various organic compounds, respectively.
Table 1.7-15 presents emission factors for hydrogen chloride and hydrogen fluoride.
Table 1.7-12 presents emission factor equations that may be used to estimate controlled and
uncontrolled emissions of nine trace metals. Table 1.7-13 presents uncontrolled emission factors for
trace metals, and Table 1.7-14 presents controlled emission factors. The emission factor equations are
based on statistical correlations among measured trace element concentrations in coal, measured
fractions of ash in coal, and measured particulate emissions. Because these are the major parameters
affecting trace metals emissions, it is recommended that the emission factor equations be used to estimate
uncontrolled and controlled emissions when the inputs to the equations are available. If the inputs to the
emission factor equations are not available for a pollutant and there is an emission factor in Table 1.7-13
or Table 1.7-14, then the emission factor(s) could be used to estimate emissions.
Tables in this section present emission factors on both a weight basis (Ib/ton) and an energy basis
(lb/1012Btu). Emission factors in units of Ib/ton can be converted to units of Ib/MMBtu by multiplying
the emission factor by 0.077, assuming a heating value for lignite of 6500 Btu/lb.
1.7.6 Updates Since the Fifth Edition
The Fifth Edition was released in January 1995. Revisions to this section since that date are
summarized below. For further detail, consult the memoranda describing each supplement or the
background report for this section. These and other documents can be found on the EFIG home page
(http://www.epa.gov/oar/oaqps/efig/).
Supplement A, February 1996
• In the table for SO^ emission factors, the footnote "f' was moved into the header of the
SOX column, and "other stoker" was clarified as a traveling grate (overfeed) stoke. Text
was added to the same table to clarify that "S" is a weight percent and not a fraction.
• In the tables for PM factors, text was added to the footnotes to clarify that "A" is a
weight percent and not a fraction.
Supplement B, October 1996
• Text was enhanced concerning lignite coal characteristics.
• Text was updated and enhanced concerning firing practices, emissions, and controls.
• The SOA emission factor was updated and a CO2 emission factor was added for all
categories.
• The table containing NOX and CO factors from controlled sources was revised to present
data by appropriate categories.
• New factors for controlled SOX were added.
1.7-6 EMISSION FACTORS 9/98
-------
• All POM factors were revised.
• New tables were added with new HAP emission factors.
• References were editorially corrected.
Supplement E, September 1998
• Table 1.7-1, the emission factor for sulfur emissions from AFBC with limestone bed
material was moved to Table 1.7-2 and no data is available for AFBC using inert bed
material.
• Tables 1.7-4 and -5, it was clarified that the FBC emissions factors are applicable to all
AFBC.
• Text was inserted to define filterable and condensable paniculate matter.
• NOX emission factors were updated for pc-fired and cyclone boilers.
• Table 1.7-2 was revised to present the techniques most frequently used to reduce SOX
emissions from coal combustion.
• The title of Table 1.7-3 was revised to specify NO, controls.
• Emission factors for condensable paniculate matter were added (Table 1.7-6).
• Conversion factor for Ib/ton to Ib/MMBtu was added to the footnotes of Tables 1.7-1,
1.7-3, 1.7-4, 1.7-5, 1.7-7, 1.7-8, 1.7-10, 1.7-11, 1.7-14 and 1.7-15.
• The term "Filterable" was inserted in the title and header rows of Tables 1.7-4 and 1.7-5.
• TNMOC data from bituminous coal were added to Table 1.7-1 in the absence of lignite
data.
9/98 External Combustion Sources 1.7-7
-------
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EMISSION FACTORS
9/98
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Table 1.7-2. POSTCOMBUSTION SO, CONTROLS FOR COAL COMBUSTION SOURCES
Control Technology
Wet Scrubber
Spray drying
Furnace injection
Duct injection
Process
Lime/limestone
Sodium carbonate
Magnesium
oxide/hydroxide
Dual alkali
Calcium hydroxide
slurry, vaporizes in
spray vessel
Dry calcium
carbonate/hydrate
injection in upper
furnace cavity
Dry sorbent injection
into duct, sometimes
combined with water
spray
Typical Control
Efficiencies
80 - 95+%
80 - 98%
80 - 95+%
90 - 96%
70 - 90%
25 - 50%
25 - 50+%
Remarks
Applicable to high sulfur
fuels, wet sludge product
5-430 million Btu/hr typical
application range, high
reagent costs
Can be regenerated
Uses lime to regenerate
sodium-based scrubbing
liquor
Applicable to low and
medium sulfur fuels,
produces dry product
Commercialized in Europe,
several U.S. demonstration
projects are completed
Several research and
development, and
demonstration projects
underway, not yet
commercially available in the
United States
Source: Reference 60.
1.7-10
EMISSION FACTORS
9/98
-------
Table 1.7-3. EMISSION FACTORS FOR NOX AND CO FROM LIGNITE
COMBUSTION WITH NO, CONTROLS2
Firing Configuration
Subpart D boilers:d
Pulverized coal,
tangential-fired
(SCC 1-01-003-02)
Pulverized coal,
wall -fired
(SCC 1-01-003-01)
Subpart Da boilers:d
Pulverized coal,
tangential-fired
(SCC 1-01-003-02)
Control
Device
Overflre Air
Overflre air
and low
NOX burners
Overfire Air
NOxb
Emission
Factor
(Ib/ton)
6.8
4.6
6.0
EMISSION
FACTOR
RATING
C
C
C
COC
Emission
Factor
(Ib/ton)
ND
0.48
0.1
EMISSION
FACTOR
RATING
NA
D
D
a To convert from Ib/ton to kg/Mg, multiply by 0.5. To convert from Ib/ton to Ib/MMBtu, multiply by
0.0625. SCC = Source Classification Code. ND = no data. NA = not applicable.
b References 22-23.
c Reference 22.
d Subpart D boilers are boilers constructed after August 17, 1971 and with a heat input rate greater than
250 million Btu per hour (MMBtu/hr). Subpart Da boilers are boilers constructed after September 18,
1978 and with a heat input rate greater than 250 MMBtu/hr.
9/98
External Combustion Sources
1.7-11
-------
Table 1.7-4. EMISSION FACTORS FOR FILTERABLE PM AND N2O FROM
UNCONTROLLED LIGNITE COMBUSTION"
EMISSION FACTOR RATING: E (except as noted)
Firing Configuration
Pulverized coal, dry bottom, tangential
(SCC 1-01-003-02)
Pulverized coal, dry bottom, wall fired
(SCC 1-01-003-01)
Cyclone (SCC 1-01-003-03)
Spreader stoker (SCC 1-01-003-06)
Other stoker (SCC 1-01-003-04)
Atmospheric fluidized bed combustor
(SCC 1-01-003-17/18)
Filterable PM Emission
Factor11 (Ib/ton)
6.5A
5.1A
6.7Ad
8.0A
3.4A
ND
N2O Emission Factor0
(Ib/ton)
ND
ND
ND
ND
ND
2.5
" To convert from Ib/ton to kg/Mg, multiply by 0.5. To convert from Ib/ton to Ib/MMBtu, multiply by
0.0625. SCC = Source Classification Code.
ND = no data.
b References 6-7, 24-25. A = weight % ash content of lignite, wet basis. For example, if the ash content
is 5%, then A = 5.
0 Reference 26.
d EMISSION FACTOR RATING: C
Table 1.7-5. EMISSION FACTORS FOR FILTERABLE PM
EMISSIONS FROM CONTROLLED LIGNITE COMBUSTION"
EMISSION FACTOR RATING: C (except as noted)
Firing Configuration
Control Device
Filterable PM Emission
Factor (Ib/ton)
Subpart D Boilersb
(SCC 1-01-003-01/-02)
Subpart Da Boilersb
(SCC 1-01-003-01/-02)
Atmospheric fluidized bed combustor
(SCC l-01-003-17/18)"-c
Baghouse
Wet scrubber
Wet scrubber
ESP
0.08A
0.05A
0.01A
0.07A
* References 22-23. A = weight % ash content of lignite, wet basis. For example, if lignite is 2.3% ash, then A =
2.3. To convert from Ib/ton to kg/Mg, multiply by 0.5. To convert from Ib/ton to Ib/MMBtu, multiply by 0.0625.
SCC = Source Classification Code.
b Subpart D boilers are boilers constructed before August 17, 1971, and with a heat input rate greater than 250
million Btu per hour (MMBtu/hr). Subpart Da boilers are boilers constructed after September 18, 1978, and with a
heat input rate greater than 250 MMBtu/hr.
c EMISSION FACTOR RATING: D.
1.7-12
EMISSION FACTORS
9/98
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EMISSION FACTORS
9/98
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>O Q •-
o tu >» u
o S .22 ^^
O *n ^i C i
r ^ ^ " r^i
eg ^ a 2
1 1 1 o S
u § § 2 .a
IfSif
^ 8 ? I ^
J^~; 53 ^
-------
Table 1.7-9. EMISSION FACTORS FOR POM FROM CONTROLLED LIGNITE COMBUSTION3
EMISSION FACTOR RATING: E
Firing Configuration
Control Device
Emission Factor (lb/1012 Btu)
POM
Pulverized coal
(SCC 1-01-003-01)
High efficiency cold-side ESP
Pulverized dry bottom
(no SCC)
Multi-cyclones
ESP
Cyclone furnace
(SCC 1-01-003-03)
Spreader stoker
(SCC 1-01-003-06)
ESP
Multi-cyclones
2.3
1.8-18"
2.6"
O.llc-1.6b
15°
a References 28-29. To convert from lb/1012 Btu to pg/J, multiply by 0.43. SCC = Source Classification
Code. ND = nodata.
b Primarily trimethyl propenyl naphthalene.
c Primarily biphenyl.
1.7-16
EMISSION FACTORS
9/98
-------
Table 1.7-10 EMISSION FACTORS FOR POLYNUCLEAR AROMATIC
HYDROCARBONS (PAH) FROM CONTROLLED COAL COMBUSTION3
Pollutant
Biphenyl
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b,j ,k)fluoranthene
Benzo(g,h,i)perylene
Chrysene
Fluoranthene
Fluorene
Indeno( 1 ,2,3-cd)pyrene
Naphthalene
Phenanthrene
Pyrene
5-Methyl chrysene
Emission Factor1"
(Ib/ton)
1.7E-06
5.1E-07
2.5E-07
2.1E-07
8.0E-08
3.8E-08
1.1E-07
2.7E-08
l.OE-07
7.1E-07
9.1E-07
6.1E-08
1.3E-05
2.7E-06
3.3E-07
2.2E-08
EMISSION FACTOR
RATING
D
B
B
B
B
D
B
D
C
B
B
C
C
B
B
D
References 30-40. Factors were developed from emissions data from six sites firing bituminous coal,
four sites firing subbituminous coal, and from one site firing lignite. Factors apply to boilers utilizing
both wet limestone scrubbers or spray dryers with an electrostatic precipitator (ESP) or fabric filter
(FF). The factors also apply to boilers utilizing only an ESP or FF. SCCs = pulverized coal-fired
boilers, 1-01-003-01, 1-02-003-01, 1-03-003-05; pulverized coal tangentially-fired boilers,
1-01-003-02, 1-02-003-02, 1-03-003-06; and cyclone boilers, 1-01-003-03, and 1-02-003-03.
Emission factor should be applied to coal feed, as fired. To convert from Ib/ton to Ib/MMBtu, multiply
by 0.0625. To convert from Ib/ton to kg/Mg, multiply by 0.5. Emissions are Ib of pollutant per ton of
coal combusted.
9/98
External Combustion Sources
1.7-17
-------
Table 1.7-11 EMISSION FACTORS FOR VARIOUS ORGANIC COMPOUNDS
FROM CONTROLLED COAL COMBUSTION3
Pollutantb
Acetaldehyde
Acetophenone
Acrolein
Benzene
Benzyl chloride
Bis(2-ethylhexyl)phthalate (DEHP)
Bromoform
Carbon disulflde
2-Chloroacetophenone
Chlorobenzene
Chloroform
Cumene
Cyanide
2,4-Dinitrotoluene
Dimethyl sulfate
Ethyl benzene
Ethyl chloride
Ethylene dichloride
Ethylene dibromide
Formaldehyde
Hexane
Isophorone
Methyl bromide
Methyl chloride
Methyl ethyl ketone
Methyl hydrazine
Methyl methacrylate
Methyl tert butyl ether
Methylene chloride
Emission Factor0
(Ib/ton)
5.7E-04
1.5E-05
2.9E-04
1.3E-03
7.0E-04
7.3E-05
3.9E-05
1.3E-04
7.0E-06
2.2E-05
5.9E-05
5.3E-06
2.5E-03
2.8E-07
4.8E-05
9.4E-05
4.2E-05
4.0E-05
1.2E-06
2.4E-04
6.7E-05
5.8E-04
1.6E-04
5.3E-04
3.9E-04
1.7E-04
2.0E-05
3.5E-05
2.9E-04
EMISSION FACTOR
RATING
C
D
D
A
D
D
E
D
E
D
D
E
D
D
E
D
D
E
E
A
D
D
D
D
D
E
E
E
D
1.7-18
EMISSION FACTORS
9/98
-------
Table 1.7-11 (continued)
Pollutantb
Phenol
Propionaldehyde
Tetrachloroethylene
Toluene
1,1,1 -Trichloroethane
Styrene
Xylenes
Vinyl acetate
Emission Factor0
(Ib/ton)
1.6E-05
3.8E-04
4.3E-05
2.4E-04
2.0E-05
2.5E-05
3.7E-05
7.6E-06
EMISSION FACTOR
RATING
D
D
D
A
E
D
C
E
References 30-48. Factors were developed from emissions data from ten sites firing bituminous coal,
eight sites firing subbituminous coal, and from one site firing lignite. The emission factors are
applicable to boilers using both wet limestone scrubbers or spray dryers and an electrostatic
precipitator (ESP) or fabric filter (FF). In addition, the factors apply to boilers utilizing only an ESP or
FF. SCCs = pulverized coal-fired boilers, 1-01-003-01, 1-02-003-01, 1-03-003-05; pulverized coal
tangentially-fired boilers, 1-01-003-02, 1-02-003-02, 1-03-003-06; cyclone boilers, 1-01-003-03,
1-02-003-03; and atmospheric fluidized bed combustor, circulating bed, 1-01-003-18. This table is
similar to Table 1.1-13 and is reproduced here for the convenience of the reader.
Pollutants sampled for but not detected in any sampling run include: Carbon tetrachloride- 2 sites;
1,3-Dichloropropylene- 2 sites; N-nitrosodimethylamine- 2 sites; Ethylidene dichloride- 2 sites;
Hexachlorobutadiene-1 site; Hexachloroethane- 1 site; Propylene dichloride- 2 sites;
1,1,2,2-Tetrachloroethane- 2 sites; 1,1,2-Trichloroethane- 2 sites; Vinyl chloride- 2 sites; and,
Hexachlorobenzene- 2 sites.
Emission factor should be applied to coal feed, as fired. To convert from Ib/ton to kg/Mg, multiply by
0.5. To convert from Ib/ton to Ib/MMBtu, multiply by 0.0625.
9/98
External Combustion Sources
1.7-19
-------
Table 1.7-12. TRACE METAL EMISSION FACTOR EQUATIONS FOR FROM COAL
COMBUSTION"
EMISSION FACTOR EQUATION RATING: Ab
Pollutant
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Cobalt
Lead
Manganese
Nickel
Emission Factor Equation
(lb/1012 Btu)c
0.92 * (C/A * PM)063
3.1*(C/A*PM)085
1.2 * (C/A * PM)1 '
3.3*(C/A*PM)05
3.7*(C/A*PM)058
1.7*(C/A*PM)069
3.4*(C/A*PM)080
3.8 * (C/A * PM)060
4.4*(C/A*PM)048
* Reference 49. The equations were developed from emissions data from bituminous coal combustion,
subbituminous coal combustion, and from lignite combustion. The equations should be used to
generate factors for controlled boilers when the necessary input information is available. The emission
factor equations are applicable to all typical firing configurations and PM controls for electric
generation (utility), industrial, and commercial/industrial boilers firing bituminous coal, subbituminous
coal, or lignite. Thus, all SCCs for these boilers are assigned to the equations.
b AP-42 criteria for rating emission factors were used to rate the equations.
c The factors produced by the equations should be applied to heat input. To convert from lb/1012 Btu to
kg/joules multiply by 4.31 x 10'16.
C = concentration of metal in the coal, parts per million by weight (ppmwt).
A = weight fraction of ash in the coal. For example, 10% ash is 0.1 ash fraction.
PM = Site-specific emission factor for total paniculate matter, lb/106 Btu.
1.7-20
EMISSION FACTORS
9/98
-------
fe
2
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8
w
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Cd
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2
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^
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trt
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s
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oo
oo
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rr\
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CN
VO
CM
t^\
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u
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^-*
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oo
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^N
IC°
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1— 1
1
NO
ON
NO
Q
g
o
00
oo
0
CO
f^»
1
CO
cs
Q
8
*— 1
1
oo
•(SCC 1-01-003-06
u
1
4>
1
cx
00
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Q
^
Q
^-«
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ON
i
r~-
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(overfed) stoker
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g>9
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3
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T3
O
II
Q
Z
-------
Table 1.7-14 EMISSION FACTORS FOR TRACE METALS FROM
CONTROLLED COAL COMBUSTION3
Pollutant
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Chromium (VI)
Cobalt
Lead
Magnesium
Manganese
Mercury
Nickel
Selenium
Emission Factor (lb/ton)b
1.8E-05
4.1E-04
2.1E-05
5.1E-05
2.6E-04
7.9E-05
l.OE-04
4.2E-04
1.1E-02
4.9E-04
8.3E-05
2.8E-04
1.3E-03
EMISSION FACTOR RATING
A
A
A
A
A
D
A
A
A
A
A
A
A
References 30-48, 50-58. The emission factors were developed from emissions data at eleven facilities
firing bituminous coal, fifteen facilities firing subbituminous coal, and from two facilities firing lignite.
The factors apply to boilers utilizing either venturi scrubbers, spray dryer absorbers, or wet limestone
scrubbers with an electrostatic precipitator (ESP) or Fabric Filter (FF). In addition, the factors apply
to boilers using only an ESP, FF, or venturi scrubber. SCCs = pulverized coal-fired boilers, 1-01-003-
01, 1-02-003-01, 1-03-003-05; pulverized coal tangentially-fired boilers, 1-01-003-02, 1-02-003-02, 1-
03-003-06; cyclone boilers, 1-01-003-03, 1-02-003-03; and atmospheric fluidized bed combustor,
circulating bed, 1-01-003-18.
Emission factor should be applied to coal feed, as fired. To convert from Ib/ton to kg/Mg, multiply by
0.5. To convert from Ib/ton to Ib/MMBtu, multiply by 0.0625.
1.7-22
EMISSION FACTORS
9/98
-------
o
u
JD
H
cn
O
I
OJ
&
o
5
s
C/3
00
w
PL
X
u
>E
c
o
*^
^-—
s
^
O
"53
M
£
'c1
o
t—
o
o
cd
U.
C
o
's
u
u
u
c
Q
1
M
g
O
OH
c
;c
in in in >n in *n
o o o o d o
CS (N C « T3 CJ
,= ,S O 0> rt
.^ V o S 00
u u >-. s o. eo
f> , p , ^J c~" C/3 [it
C
o
§1
t; ^
« c
> S
n o
o c
o g
r1^ C
C3
ni -O
ta ^
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00 V-
11
ll
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'c ^
s "cl
T3 2*
c ^
—* o
« u
8 <*2
00 1)
3 J3
•|^
3 CS
.« 'O
•§d
_, ^i
"c3 >->
o ~?z
o .S4
3 3
o S
c c
'S 2
2«
3S
EjS
o >
C" "^i
CL C
_o o
2 §
O O
<*- o
cH
.2 •
w */^
• p O
c ^«»
o ft
.
£ "o^
*-^
a Reference 59.
to kg/Mg, mu
sources.
9/98
External Combustion Sources
1.7-23
-------
3A
2.7A
2 2.4A
J©
e 1 2-1A
o IQ
| S3 1.8A
"1 1.5A
1.2A
0.9A
0.6A
0.3A
0
.1
Multiple
cyclone
Uncontrolled
l.OA
0.9A
0.8A
0.7A
0.6A
0.5A
0.4A
0.3A
0.2A
0.1A
0
.4 .6 1 2 4 6 10
Particle diameter ( m)
20
40 60 100
I
o
.a a
§8
O w,
o
J2
15.
4-»
I
Figure 1.7-1. Cumulative size-specific emission factors for boilers
firing pulverized lignite.
-------
References For Section 1.7
1. Kirk-Othmer Encyclopedia Of Chemical Technology, Second Edition, Volume 12, John Wiley
and Sons, New York, NY, 1967.
2. G. H. Gronhovd, et al., "Some Studies on Stack Emissions from Lignite Fired Powerplants",
Presented at the 1973 Lignite Symposium, Grand Forks, ND, May 1973.
3. Standards Support And Environmental Impact Statement: Promulgated Standards Of
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030b, U. S. Environmental Protection Agency, Research Triangle Park, NC, December 1976.
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Sons, Inc., 1991,p.239
6. Source Test Data On Lignite-Fired Power Plants, North Dakota State Department of Health,
Bismarck, ND, December 1973.
7. G. H. Gronhovd, et al., "Comparison Of Ash Fouling Tendencies Of High And Low Sodium
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XXVUI, 1966.
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Emissions From Utility Boilers, EPA-650/2-74-066, U. S. Environmental Protection Agency,
Washington, DC, June 1974.
3. Nitrogen Oxides Emission Measurements For Three Lignite Fired Power Plants,
Contract No. 68-02-1401 And 68-02-1404, Office Of Air Quality Planning And Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, 1974.
10. Coal Fired Power Plant Trace Element Study, A Three Station Comparison, U. S. Environmental
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Sulfur Emissions From Pulverized Coal Fired Steam Generators, EPA-450/3-77-047,
U. S. Environmental Protection Agency, Research Triangle Park, NC, December 1977.
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Volume III: External Combustion Sources For Electricity Generation, EPA
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Fouling Potential For A Lignite-Fired Boiler", Proceedings of the American Power Conference,
Volume 40,1978.
14. Emission Factor Documentation For AP-42 Section 1.7, Lignite Combustion, prepared by
Acurex Environmental Corp., Edward Aul & Associates, Inc., and E. H. Pechan & Associates,
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Combustion Sources Of NO,, N2O, CH4, CO, And CO2, EPA Contract No. 68-02-4288, Research
Triangle Park, NC: Radian Corporation, 1990.
9/98 External Combustion Sources 1.7-25
-------
18. G. Marland, and R.M. Rotty Carbon Dioxide Emissions From Fossil Fuels: A Procedure For
Estimation And Results For 1951-1981, DOE/NBB-0036 TR-003, Carbon Dioxide Research
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25. Personal communication dated September 18, 1981, Letter from North Dakota Department of
Health to Mr. Bill Larnson of the U. S. Environmental Protection Agency, Research Triangle
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34. Field Chemical Emissions Monitoring Project: Site 21 Emissions Monitoring. Radian
Corporation, Austin, Texas. August, 1993. (EPRI Report)
1.7-26 EMISSION FACTORS 9/98
-------
35. Field Chemical Emissions Monitoring Project: Site 111 Emissions Report. Radian Corporation,
Austin, Texas. May, 1993. (EPRI Report)
36. Field Chemical Emissions Monitoring Project: Site 115 Emissions Report. Radian Corporation,
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NSP High Bridge Plant. Interpoll Laboratories, Inc., Circle Pines, Minnesota. January 3, 1992.
42. Results of the December 1991 Air Toxic Emission Study on Units 6 & 7 at the NSP Riverside
Plant. Interpoll Laboratories, Inc., Circle Pines, Minnesota. February 28, 1992.
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44. Field Chemical Emissions Monitoring Project: Site 12 Emissions Monitoring. Radian
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Pines, Minnesota. July, 1990.
9/98 External Combustion Sources 1.7-27
-------
54. Results of the May 1, 1990 Trace Metal Characterization Study on Units 1 and 2 at the
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Street Station Units 7, 8, 9 Inlets/Outlets. Mostardi-Platt Associates, Inc. December 6, 1994.
64. Paniculate Emission Study Performed for Marshfield Electric and Water Department at the
Wildwood Station Marshfield Wisconsin Boiler 5 Stack. Mostardi-Platt Associates, Inc.
January 23-25, 1990.
65. Report on Particulate, SO2, and NOX Compliance Testing. Dairyland Power Cooperative J.P.
Madgett Stack. Alma, Wisconsin. CAE. January 6, 1995.
66. Particulate Emissions Test Results. Portland General Electric Coal-fired Power Plant.
Boardman, Oregon. SAIC, Inc. January 25, 1994.
67. Report on Compliance Testing Performed at Marshfield Electric and Water Department
Wildwood Station Unit 5, Marshfield, Wisconsin. Clean Air Engineering, December 11,1989.
68. Portland General Electric Company Boardman Coal Plant. Unit #1 Coal-fired Boiler.
Boardman, Oregon. August 24-27,1995.
69. Particulate Emission Compliance Study Performed for Portland General Electric at the Boardman
Plant Unit 1 Stack. Boardman, Oregon. September 19, 1996.
70. Emissions Source Test Report. Portland General Electric Coal-Fired Power Plant. Boardman,
Oregon. OMNI Environmental Services, Inc. October 17, 1990.
71. Source Emissions Test Report Compliance. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services. January 29, 1991.
1.7-28 EMISSION FACTORS 9/98
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72. Source Test Report. Particulate Emissions. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. January 14, 1991.
73. Emissions Source Test Rpeort. Portland General Electric Coal-Fired Power Plant. Boardman,
Oregon. OMNI Environmental Services, Inc. April 3, 1991.
74. Source Emissions Test Report. Portland General Electric Coal-Fired Power Plant. Boardman,
Oregon. OMNI Environmental Services, Inc. January 21,1992.
75. Particulate Emissions Test Results. Portland General Electric Coal-fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. April 4, 1992.
76. Particulate Emissions Test Results. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. September 9, 1992.
77. Particulate Emissions Test Results. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. November 6, 1992.
78. Particulate Emissions Test Results. Portland General Electric Coal-Fired Power Plant.
Boardman, Oregon. OMNI Environmental Services, Inc. January 26, 1993.
79. Stationary Source Sampling Report. Keystone Cogeneration Facility. Keystone Cogeneration
Facility. Logan Township, NJ. November 1994.
80. Source Emissions Survey of City Public Service Board J.K. Spruce Unit Number 1 Stack.
METCO Environmental. December 1992.
81. Report of Particulate Emission Testing on the Number 1 Boiler at Associated Milk Products
Incorporated Located in Jim Falls, Wisconsin. Environmental Services of American, Inc.
November 1994.
82. Appletone Papers, Inc. Boiler Emission Test at Appleton, WI. May 11 and 12, 1993. Badger
Laboratories and Engineering.
83. Appleton Papers, Inc. Boiler Emission Test Report at Appleton, WI. Badger Laboratories and
Engineering. October 11, 1993.
84. Results of a Source Emission Compliance Test on Boiler #2 at the Hills Farm Heating Plant,
Madison, Wisconsin. MMT Environmental Services, Inc. January 22, 1993.
85. Results of a Source Emission Compliance Test on Boiler #2 at the Hills Farm Heating Plant,
Madison, Wisconsin. MMT Environmental Services, Inc. March 2, 1995.
86. Report to Mosinee Paper Company for Particulate Matter Emission Testing. No. 6 Boiler at
Mosinee, Wisconsin. May 18, 19, and 20, 1993.
87. Report to Milwaukee County for Particulate Matter Emission Test Boiler No. 21. Environmental
Technology and Engineering Corporation. Novembers, 1991.
88. Report on Compliance Testing Conducted at Oscar Mayer Foods Corporation, Madison,
Wisconsin. Clean Air Engineering. July 21,1989.
9/98 External Combustion Sources 1.7-29
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2.4 MUNICIPAL SOLID WASTE LANDFILLS
2.4.1 General1-4
A municipal solid waste (MSW) landfill unit is a discrete area of land or an excavation that receives
household waste, and that is not a land application unit, surface impoundment, injection well, or waste pile.
An MSW landfill unit may also receive other types of wastes, such as commercial solid waste, nonhazardous
sludge, and industrial solid waste. The municipal solid waste types potentially accepted by MSW landfills
include (most landfills accept only a few of the following categories):
• MSW,
• Household hazardous waste,
• Municipal sludge,
• Municipal waste combustion ash,
• Infectious waste,
• Waste tires,
• Industrial non-hazardous waste,
• Conditionally exempt small quantity generator (CESQG) hazardous waste,
• Construction and demolition waste,
• Agricultural wastes,
• Oil and gas wastes, and
• Mining wastes.
In the United States, approximately 57 percent of solid waste is landfilled, 16 percent is incinerated, and
27 percent is recycled or composted. There were an estimated 2,500 active MSW landfills in the United
States in 1995. These landfills were estimated to receive 189 million megagrams (Mg) (208 million tons) of
waste annually, with 55 to 60 percent reported as household waste, and 35 to 45 percent reported as
commercial waste.
2.4.2 Process Description2'5
There are three major designs for municipal landfills. These are the area, trench, and ramp methods. All
of these methods utilize a three step process, which includes spreading the waste, compacting the waste, and
covering the waste with soil. The trench and ramp methods are not commonly used, and are not the preferred
methods when liners and leachate collection systems are utilized or required by law. The area fill method
involves placing waste on the ground surface or landfill liner, spreading it in layers, and compacting with
heavy equipment. A daily soil cover is spread over the compacted waste. The trench method entails
excavating trenches designed to receive a day's worth of waste. The soil from the excavation is often used for
cover material and wind breaks. The ramp method is typically employed on sloping land, where waste is
spread and compacted similar to the area method, however, the cover material obtained is generally from the
front of the working face of the filling operation.
Modern landfill design often incorporates liners constructed of soil (i.e., recompacted clay), or synthetics
(i.e., high density polyethylene), or both to provide an impermeable barrier to leachate (i.e., water that has
passed through the landfill) and gas migration from the landfill.
11/98 Solid Waste Disposal 2.4-1
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2.4.3 Control Technology1-2'6
The Resource Conservation and Recovery Act (RCRA) Subtitle D regulations promulgated on
October 9,1991 require that the concentration of methane generated by MSW landfills not exceed 25 percent
of the lower explosive limit (LEL) in on-site structures, such as scale houses, or the LEL at the facility
property boundary.
The New Source Performance Standards (NSPS) and Emission Guidelines for air emissions from MSW
landfills for certain new and existing landfills were published in the Federal Register on March 1,1996. The
regulation requires that Best Demonstrated Technology (BDT) be used to reduce MSW landfill emissions
from affected new and existing MSW landfills emitting greater than or equal to 50 Mg/yr (55 tons/yr) of non-
methane organic compounds (NMOCs). The MSW landfills that are affected by the NSPS/Emission
Guidelines are each new MSW landfill, and each existing MSW landfill that has accepted waste since
November 8,1987, or that has capacity available for future use. The NSPS/Emission Guidelines affect
landfills with a design capacity of 2.5 million Mg (2.75 million tons) or more. Control systems require: (1) a
well-designed and well-operated gas collection system, and (2) a control device capable of reducing NMOCs
in the collected gas by 98 weight-percent.
Landfill gas (LFG) collection systems are either active or passive systems. Active collection systems
provide a pressure gradient in order to extract LFG by use of mechanical blowers or compressors. Passive
systems allow the natural pressure gradient created by the increase in pressure created by LFG generation
within the landfill to mobilize the gas for collection.
LFG control and treatment options include (1) combustion of the LFG, and (2) purification of the LFG.
Combustion techniques include techniques that do not recover energy (i.e., flares and thermal incinerators),
and techniques that recover energy (i.e., gas turbines and internal combustion engines) and generate electricity
from the combustion of the LFG. Boilers can also be employed to recover energy from LFG in the form of
steam. Flares involve an open combustion process that requires oxygen for combustion, and can be open or
enclosed. Thermal incinerators heat an organic chemical to a high enough temperature in the presence of
sufficient oxygen to oxidize the chemical to carbon dioxide (CO2) and water. Purification techniques can
also be used to process raw landfill gas to pipeline quality natural gas by using adsorption, absorption, and
membranes.
2.4.4 Emissions2'7
Methane (CH4) and CO2 are the primary constituents of landfill gas, and are produced by
microorganisms within the landfill under anaerobic conditions. Transformations of CH4 and CO2 are
mediated by microbial populations that are adapted to the cycling of materials in anaerobic environments.
Landfill gas generation, including rate and composition, proceeds through four phases. The first phase is
aerobic [i.e., with oxygen (O2) available] and the primary gas produced is CO2. The second phase is
characterized by O2 depletion, resulting in an anaerobic environment, where large amounts of CO2 and some
hydrogen (H2) are produced. In the third phase, CH4 production begins, with an accompanying reduction in
the amount of CO2 produced. Nitrogen (N2) content is initially high in landfill gas in the first phase, and
declines sharply as the landfill proceeds through the second and third phases. In the fourth phase, gas
production of CH4, CO2, and N2 becomes fairly steady. The total time and phase duration of gas generation
varies with landfill conditions (i.e., waste composition, design management, and anaerobic state).
Typically, LFG also contains a small amount of non-methane organic compounds (NMOC). This
NMOC fraction often contains various organic hazardous air pollutants (HAP), greenhouse gases (GHG),
and compounds associated with stratospheric ozone depletion. The NMOC fraction also contains volatile
2.4-2 EMISSION FACTORS 11/98
-------
organic compounds (VOC). The weight fraction of VOC can be determined by subtracting the weight
fractions of individual compounds that are non-photochemically reactive (i.e., negligibly-reactive organic
compounds as defined in 40 CFR 51.100).
Other emissions associated with MSW landfills include combustion products from LFG control and
utilization equipment (i.e., flares, engines, turbines, and boilers). These include carbon monoxide (CO),
oxides of nitrogen (NOX), sulfur dioxide (SO2), hydrogen chloride (HC1), particulate matter (PM) and other
combustion products (including HAPs). PM emissions can also be generated in the form of fugitive dust
created by mobile sources (i.e., garbage trucks) traveling along paved and unpaved surfaces. The reader
should consult AP-42 Volume I Sections 13.2.1 and 13.2.2 for information on estimating fugitive dust
emissions from paved and unpaved roads.
The rate of emissions from a landfill is governed by gas production and transport mechanisms.
Production mechanisms involve the production of the emission constituent in its vapor phase through
vaporization, biological decomposition, or chemical reaction. Transport mechanisms involve the
transportation of a volatile constituent in its vapor phase to the surface of the landfill, through the air
boundary layer above the landfill, and into the atmosphere. The three major transport mechanisms that
enable transport of a volatile constituent in its vapor phase are diffusion, convection, and displacement.
2.4.4.1 Uncontrolled Emissions — To estimate uncontrolled emissions of the various compounds present in
landfill gas, total landfill gas emissions must first be estimated. Uncontrolled CH4 emissions may be
estimated for individual landfills by using a theoretical first-order kinetic model of methane production
developed by the EPA.8 This model is known as the Landfill Air Emissions Estimation model, and can be
accessed from the Office of Air Quality Planning and Standards Technology Transfer Network Website
(OAQPS TTN Web) in the Clearinghouse for Inventories and Emission Factors (CHIEF) technical area
(URL http://www.epa.gov/ttn/chief). The Landfill Air Emissions Estimation model equation is as follows:
QCH, = Lo R (e ~kc - e ~kt> (1)
where:
= Methane generation rate at time t, m3/yr;
Lo = Methane generation potential, m3 CH4/Mg refuse;
R = Average annual refuse acceptance rate during active life, Mg/yr;
e = Base log, unitless;
k = Methane generation rate constant, yr"1;
c = Time since landfill closure, yrs (c = 0 for active landfills); and
t = Time since the initial refuse placement, yrs.
It should be noted that the model above was designed to estimate LFG generation and not LFG emissions
to the atmosphere. Other fates may exist for the gas generated in a landfill, including capture and subsequent
microbial degradation within the landfill's surface layer. Currently, there are no data that adequately address
this fate. It is generally accepted that the bulk of the gas generated will be emitted through cracks or other
openings in the landfill surface.
Site-specific landfill information is generally available for variables R, c, and t. When refuse acceptance
rate information is scant or unknown, R can be determined by dividing the refuse in place by the age of the
landfill. If a facility has documentation that a certain segment (cell) of a landfill received only nondegradable
refuse, then the waste from this segment of the landfill can be excluded from the calculation of R.
Nondegradable refuse includes concrete, brick, stone, glass, plaster, wallboard, piping, plastics, and metal
1/98 Solid Waste Disposal 2.4-3
-------
objects. The average annual acceptance rate should only be estimated by this method when there is
inadequate information available on the actual average acceptance rate. The time variable, t, includes the
total number of years that the refuse has been in place (including the number of years that the landfill has
accepted waste and, if applicable, has been closed).
Values for variables L0 and k must be estimated. Estimation of the potential CH4 generation capacity of
refuse (L0) is generally treated as a function of the moisture and organic content of the refuse. Estimation of
the CH4 generation constant (k) is a function of a variety of factors, including moisture, pH, temperature, and
other environmental factors, and landfill operating conditions. Specific CH4 generation constants can be
computed by the use of EPA Method 2E (40 CFR Part 60 Appendix A).
The Landfill Air Emission Estimation model includes both regulatory default values and recommended
AP-42 default values for L0 and k. The regulatory defaults were developed for compliance purposes
(NSPS/Emission Guideline). As a result, the model contains conservative L0 and k default values in order to
protect human health, to encompass a wide range of landfills, and to encourage the use of site-specific data.
Therefore, different L0 and k values may be appropriate in estimating landfill emissions for particular
landfills and for use in an emissions inventory.
Recommended AP-42 defaults include a k value of 0.04/yr for areas recieving 25 inches or more of rain
per year. A default k of 0.02/yr should be used in drier areas (<25 inches/yr). An L0 value of 100 m3/Mg
(3,530 ft3/ton) refuse is appropriate for most landfills. Although the recommended default k and L0 are
based upon the best fit to 21 different landfills, the predicted methane emissions ranged from 38 to 492% of
actual, and had a relative standard deviation of 0.85. It should be emphasized that in order to comply with the
NSPS/Emission Guideline, the regulatory defaults for k and L0 must be applied as specified in the final rule.
When gas generation reaches steady state conditions, LFG consists of approximately 40 percent by
volume CO2, 55 percent CH4, 5 percent N2 (and other gases), and trace amounts of NMOCs. Therefore, the
estimate derived for CH4 generation using the Landfill Air Emissions Estimation model can also be used to
represent CO2 generation. Addition of the CH4 and CO2 emissions will yield an estimate of total landfill gas
emissions. If site-specific information is available to suggest that the CH4 content of landfill gas is not
55 percent, then the site-specific information should be used, and the CO2 emission estimate should be
adjusted accordingly.
Most of the NMOC emissions result from the volatilization of organic compounds contained in the
landfilled waste. Small amounts may be created by biological processes and chemical reactions within the
landfill. The current version of the Landfill Air Emissions Estimation model contains a proposed regulatory
default value for total NMOC of 4,000 ppmv, expressed as hexane. However, available data show that there
is a range of over 4,400 ppmv for total NMOC values from landfills. The proposed regulatory default value
for NMOC concentration was developed for regulatory compliance purposes and to provide the most
cost-effective default values on a national basis. For emissions inventory purposes, site-specific information
should be taken into account when determining the total NMOC concentration. In the absence of site-specific
information, a value of 2,420 ppmv as hexane is suggested for landfills known to have co-disposal of MSW
and non-residential waste. If the landfill is known to contain only MSW or have very little organic
commercial/industrial wastes, then a total NMOC value of 595 ppmv as hexane should be used. In addition,
as with the landfill model defaults, the regulatory default value for NMOC content must be used in order to
comply with the NSPS/Emission Guideline.
If a site-specific total pollutant concentration is available (i.e., as measured by EPA Reference Method
25C), it must be corrected for air infiltration which can occur by two different mechanisms: LFG sample
dilution, and air intrusion into the landfill. These corrections require site-specific data for the LFG CH4,
2.4-4 EMISSION FACTORS 11/98
-------
CO2, nitrogen (N2), and oxygen (O2) content. If the ratio of N2 to O2 is less than or equal to 4.0 (as found in
ambient air), then the total pollutant concentration is adjusted for sample dilution by assuming that CO2 and
CH4 are the primary (100 percent) constituents of landfill gas, and the following equation is used:
Cp (ppmv) (1 x 106)
Cp (ppmv) (corrected for air infiltration) = - (2)
CC02 (PPmV) + CCH4 (PPmV)
where:
Cp = Concentration of pollutant P in landfill gas (i.e., NMOC as hexane), ppmv;
= CO2 concentration in landfill gas, ppmv.
= CH4 Concentration in landfill gas, ppmv; and
1 x 106 = Constant used to correct concentration of P to units of ppmv.
If the ratio of N2 to O2 concentrations (i.e., Cj$ , CQ ) is greater than 4.0, then the total pollutant
concentration should be adjusted for air intrusion into the landfill by using equation 2 and adding the
concentration of N2 (i.e., CN ) to the denominator. Values for C^O , C^H , CN , CQ , can usually be
found in the source test report for the particular landfill along with the total pollutant concentration data.
To estimate emissions of NMOC or other landfill gas constituents, the following equation should be
used:
Qp = 1.82 Q * - p— (3)
4 (1 x 106)
where:
Qp = Emission rate of pollutant P (i.e. NMOC), m3/yr;
generation rate, m3/yr (from the Landfill Air Emissions Estimation model);
Cp = Concentration of Pin landfill gas, ppmv; and
1 .82 = Multiplication factor (assumes that approximately 55 percent of landfill gas is CH4
and 45 percent is CO2, N2, and other constituents).
Uncontrolled mass emissions per year of total NMOC (as hexane), CO2, CH4, and speciated organic and
inorganic compounds can be estimated by the following equation:
MWP * 1 atm
UMP = Qp * P
(4)
(8.2Q5xlO~5 m3-atrn/gmol-°K)(1000g/kg)(273 +T°K)
where:
UMp = Uncontrolled mass emissions of pollutant P (i.e., NMOC), kg/yr;
MWp = Molecular weight of P, g/gmol (i.e., 86.18 for NMOC as hexane);
Qp = NMOC emission rate pf P, m3/yr; and
T = Temperature of landfill gas, °C.
This equation assumes that the operating pressure of the system is approximately 1 atmosphere. If the
temperature of the landfill gas is not known, a temperature of 25°C (77°F) is recommended.
11/98 Solid Waste Disposal 2.4-5
-------
Uncontrolled default concentrations of speciated organics along with some inorganic compounds are
presented in Table 2.4-1. These default concentrations have already been corrected for air infiltration and can
be used as input parameters to equation 3 or the Landfill Air Emission Estimation model for estimating
speciated emissions from landfills when site-specific data are not available. An analysis of the data, based on
the co-disposal history (with non-residential wastes) of the individual landfills from which the concentration
data were derived, indicates that for benzene, NMOC, and toluene, there is a difference in the uncontrolled
concentrations. Table 2.4-2 presents the corrected concentrations for benzene, NMOC, and toluene to use
based on the site's co-disposal history.
It is important to note that the compounds listed in Tables 2.4-1 and 2.4-2 are not the only compounds
likely to be present in LFG. The listed compounds are those that were identified through a review of the
available literature. The reader should be aware that additional compounds are likely present, such as those
associated with consumer or industrial products. Given this information, extreme caution should be exercised
in the use of the default VOC weight fractions and concentrations given at the bottom of Table 2.4-2. These
default VOC values are heavily influenced by the ethane content of the LFG. Available data have shown that
there is a range of over 1,500 ppmv in LFG ethane content among landfills.
2.4.4.2 Controlled Emissions — Emissions from landfills are typically controlled by installing a gas
collection system, and combusting the collected gas through the use of internal combustion engines, flares, or
turbines. Gas collection systems are not 100 percent efficient in collecting landfill gas, so emissions of CH4
and NMOC at a landfill with a gas recovery system still occur. To estimate controlled emissions of CH4,
NMOC, and other constituents in landfill gas, the collection efficiency of the system must first be estimated.
Reported collection efficiencies typically range from 60 to 85 percent, with an average of 75 percent most
commonly assumed. Higher collection efficiencies may be achieved at some sites (i.e., those engineered to
control gas emissions). If site-specific collection efficiencies are available (i.e., through a comprehensive
surface sampling program), then they should be used instead of the 75 percent average.
Controlled emission estimates also need to take into account the control efficiency of the control device.
Control efficiencies based on test data for the combustion of CH4, NMOC, and some speciated organics with
differing control devices are presented in Table 2.4-3. Emissions from the control devices need to be added
to the uncollected emissions to estimate total controlled emissions.
Controlled CH4, NMOC, and speciated emissions can be calculated with equation 5. It is assumed that
the landfill gas collection and control system operates 100 percent of the time. Minor durations of system
downtime associated with routine maintenance and repair (i.e., 5 to 7 percent) will not appreciably effect
emission estimates. The first term in equation 5 accounts for emissions from uncollected landfill gas, while
the second term accounts for emissions of the pollutant that were collected but not combusted in the control
or utilization device:
CMp =
UMD * 1 -
led
100,
where:
UMD *
ent
P
100 100,
(5)
CMp = Controlled mass emissions of pollutant P, kg/yr;
UMp = Uncontrolled mass emissions of P, kg/yr (from equation 4 or the Landfill Air
Emissions Estimation Model);
^col = Collection efficiency of the landfill gas collection system, percent; and
r|cnt = Control efficiency of the landfill gas control or utilization device, percent.
2.4-6 EMISSION FACTORS 11/98
-------
Emission factors for the secondary compounds, CO and NOX, exiting the control device are
presented in Tables 2.4-4 and 2.4-5. These emission factors should be used when equipment vendor
guarantees are not available.
Controlled emissions of CO2 and sulfur dioxide (SO2) are best estimated using site-specific landfill gas
constituent concentrations and mass balance methods.68 If site-specific data are not available, the data in
tables 2.4-1 through 2.4-3 can be used with the mass balance methods that follow.
Controlled CO2 emissions include emissions from the CO2 component of landfill gas (equivalent to
uncontrolled emissions) and additional CO2 formed during the combustion of landfill gas. The bulk of the
CO2 formed during landfill gas combustion comes from the combustion of the CH4 fraction. Small quantities
will be formed during the combustion of the NMOC fraction, however, this typically amounts to less than 1
percent of total CO2 emissions by weight. Also, the formation of CO through incomplete combustion of
landfill gas will result in small quantities of CO2 not being formed. This contribution to the overall mass
balance picture is also very small and does not have a significant impact on overall CO2 emissions.
The following equation which assumes a 100 percent combustion efficiency for CH4 can be used to
estimate CO2 emissions from controlled landfills:
oz = UMco,
where:
UM * — * 2.75
ACH
•4
100
T}col
2.75
Controlled mass emissions of CO2, kg/yr;
Uncontrolled mass emissions of CO2, kg/yr (from equation 4 or the Landfill Air
Emission Estimation Model);
Uncontrolled mass emissions of CH4, kg/yr (from equation 4 on the Landfill Air
Emission Estimation Model);
Efficiency of the landfill gas collection system, percent; and
Ratio of the molecular weight of CO2 to the molecular weight of CH4.
To prepare estimates of SO2 emissions, data on the concentration of reduced sulfur compounds within
the landfill gas are needed. The best way to prepare this estimate is with site-specific information on the total
reduced sulfur content of the landfill gas. Often these data are expressed in ppmv as sulfur (S). Equations 3
and 4 should be used first to determine the uncontrolled mass emission rate of reduced sulfur compounds as
sulfur. Then, the following equation can be used to estimate SO2 emissions:
CMsn = UMS * -^- * 2.0 (7)
so2 s 100
where:
CM$o7 = Controlled mass emissions of SO2, kg/yr;
UM§ = Uncontrolled mass emissions of reduced sulfur compounds as sulfur, kg/yr (from
equations 3 and 4);
rj^j = Efficiency of the landfill gas collection system, percent; and
2.0 = Ratio of the molecular weight of SO2 to the molecular weight of S.
The next best method to estimate SO2 concentrations, if site-specific data for total reduced sulfur
compounds as sulfur are not available, is to use site-specific data for speciated reduced sulfur compound
concentrations. These data can be converted to ppmv as S with equation 8. After the total reduced sulfur as
S has been obtained from equation 8, then equations 3, 4, and 7 can be used to derive SO2 emissions.
11/98 Solid Waste Disposal 2.4-7
-------
CS = "-l CP * SP
where:
Cg = Concentration of total reduced sulfur compounds, ppmv as S (for use in equation 3);
Cp = Concentration of each reduced sulfur compound, ppmv;
Sp = Number of moles of S produced from the combustion of each reduced sulfur
compound (i.e., 1 for sulfides, 2 for disulfides); and
n = Number of reduced sulfur compounds available for summation.
If no site-specific data are available, a value of 46.9 ppmv can be assumed for Cs (for use in equation 3).
This value was obtained by using the default concentrations presented in Table 2.4-1 for reduced sulfur
compounds and equation 8.
Hydrochloric acid [Hydrogen Chloride (HC1)] emissions are formed when chlorinated compounds in
LFG are combusted in control equipment. The best methods to estimate emissions are mass balance methods
that are analogous to those presented above for estimating SO2 emissions. Hence, the best source of data to
estimate HC1 emissions is site-specific LFG data on total chloride [expressed in ppmv as the chloride ion
(Cl~)]. If these data are not available, then total chloride can be estimated from data on individual chlorinated
species using equation 9 below. However, emission estimates may be underestimated, since not every
chlorinated compound in the LFG will be represented in the laboratory report (i.e., only those that the
analytical method specifies).
* Clp (9)
where:
CQ = Concentration of total chloride, ppmv as Cl" (for use in equation 3);
Cp = Concentration of each chlorinated compound, ppmv;
Clp = Number of moles of Cl" produced from the combustion of each chlorinated
compound (i.e., 3 for 1,1,1-trichloroethane); and
n = Number of chlorinated compounds available for summation.
After the total chloride concentration (CC1) has been estimated, equations 3 and 4 should be used to
determine the total uncontrolled mass emission rate of chlorinated compounds as chloride ion (UMQ). This
value is then used in equation 10 below to derive HC1 emission estimates:
CMHn - UMn * * 1.03 *
HCI ci
(10)
where:
= Controlled mass emissions of HCI, kg/yr;
= Uncontrolled mass emissions of chlorinated compounds as chloride, kg/yr (from
equations 3 and 4);
Tlcol = Efficiency of the landfill gas collection system, percent;
1.03 = Ratio of the molecular weight of HCI to the molecular weight of Cl"; and
T|cnt = Control efficiency of the landfill gas control or utilization device, percent.
2.4-8 EMISSION FACTORS 11/98
-------
In estimating HC1 emissions, it is assumed that all of the chloride ion from the combustion of chlorinated
LFG constituents is converted to HC1. If an estimate of the control efficiency, T|cnt, is not available, then the
high end of the control efficiency range for the equipment listed in Table 9 should be used. This assumption
is recommended to assume that HC1 emissions are not under-estimated.
If site-specific data on total chloride or speciated chlorinated compounds are not available, then a default
value of 42.0 ppmv can be used for Ca. This value was derived from the default LFG constituent
concentrations presented in Table 2.4-1. As mentioned above, use of this default may produce
underestimates of HC1 emissions since it is based only on those compounds for which analyses have been
performed. The constituents listed in Table 2.4-1 are likely not all of the chlorinated compounds present in
LFG.
The reader is referred to Sections 11.2-1 (Unpaved Roads, SCC 50100401), and 11-2.4 (Heavy
Construction Operations) of Volume I, and Section n-7 (Construction Equipment) of Volume n, of the
AP-42 document for determination of associated fugitive dust and exhaust emissions from these emission
sources at MSW landfills.
2.4.5 Updates Since the Fifth Edition
The Fifth Edition was released in January 1995. Supplemnt D (8/98) is a major revision of the text and
recommended emission factors conained in the section. The most significant revisions to this section since
publication in the Fifth Edition are summarized below.
• The equations to calculate the CH4, CO2 and other constituents were simplified.
• The default LQ and k were revised based upon an expanded base of gas generation data.
• The default ratio of CO2 to CH4 was revised based upon averages observed in available source test
reports.
• The default concentrations of LFG constituents were revised based upon additional data.
• Additional control efficiencies were included and existing efficiencies were revised based upon
additional emission test data.
• Revised and expanded the recommended emission factors for secondary compounds emitted from
typical control devices.
Supplement E (11/98) includes correction in equation 10 and a very minor change in the molecular weights
for 1,1,1-Trichloroethane (methyl chloroform), 1,1-Dichloroethane, 1,2-Dichloropropane and
Trichloroethylene (trichloroethene) presented in Table 2.4-1 to agree with values presented in Perry's
Handbook.
11/98 Solid Waste Disposal 2.4-9
-------
Table 2.4-1. DEFAULT CONCENTRATIONS FOR LFG CONSTITUENTS3
(SCC 50100402, 50300603)
Compound
1,1,1-Trichloroethane (methyl chloroform)3
1 , 1 ,2,2-Tetrachloroethanea
1,1-Dichloroethane (ethylidene dichloride)3
1,1-Dichloroethene (vinylidene chloride)3
1,2-Dichloroethane (ethylene dichloride)3
1,2-Dichloropropane (propylene dichloride)3
2-Propanol (isopropyl alcohol)
Acetone
Acrylonitrile3
Bromodichloromethane
Butane
Carbon disulfide3
Carbon monoxideb
Carbon tetrachloride3
Carbonyl sulfide3
Chlorobenzene3
Chlorodifluoromethane
Chloroethane (ethyl chloride)3
Chloroform3
Chloromethane
Dichlorobenzenec
Dichlorodifluoromethane
Dichlorofluoromethane
Dichloromethane (methylene chloride)3
Dimethyl sulfide (methyl sulfide)
Ethane
Ethanol
Ethyl mercaptan (ethanethiol)
Ethylbenzene3
Ethylene dibromide
Fluorotrichloromethane
Hexane3
Hydrogen sulfide
Mercury (total)a'd
Molecular Weight
133.41
167.85
98.97
96.94
98.96
112.99
60.11
58.08
53.06
163.83
58.12
76.13
28.01
153.84
60.07
112.56
86.47
64.52
119.39
50.49
147
120.91
102.92
84.94
62.13
30.07
46.08
62.13
106.16
187.88
137.38
86.18
34.08
200.61
Default
Concentration
(ppmv)
0.48
1.11
2.35
0.20
0.41
0.18
50.1
7.01
6.33
3.13
5.03
0.58
141
0.004
0.49
0.25
1.30
1.25
0.03
1.21
0.21
15.7
2.62
14.3
7.82
889
27.2
2.28
4.61
0.001
0.76
6.57
35.5
2.92x1 0-4
Emission Factor
Rating
B
C
B
B
B
D
E
B
D
C
C
C
E
B
D
C
C
B
B
B
E
A
D
A
C
C
E
D
B
E
B
B
B
E
2.4-10
EMISSION FACTORS
11/98
-------
Table 2.4-1. (Concluded)
Compound
Methyl ethyl ketone3
Methyl isobutyl ketone3
Methyl mercaptan
Pentane
Perchloroethylene (tetrachloroethylene)3
Propane
t- 1 ,2-dichloroethene
Trichloroethylene (trichloroethene)3
Vinyl chloride3
Xylenes3
Molecular Weight
72.11
100.16
48.11
72.15
165.83
44.09
96.94
131.40
62.50
106.16
Default
Concentration
(ppmv)
7.09
1.87
2.49
3.29
3.73
11.1
2.84
2.82
7.34
12.1
Emission Factor
Rating
A
B
C
C
B
B
B
B
B
B
NOTE: This is not an all-inclusive list of potential LFG constituents, only those for which test data were
available at multiple sites. References 10-67. Source Classification Codes in parentheses.
a Hazardous Air Pollutants listed in Title III of the 1990 Clean Air Act Amendments.
b Carbon monoxide is not a typical constituent of LFG, but does exist in instances involving landfill
(underground) combustion. Therefore, this default value should be used with caution. Of 18 sites where CO was
measured, only 2 showed detectable levels of CO.
c Source tests did not indicate whether this compound was the para- or ortho- isomer. The para isomer is a Title
m-listed HAP.
d No data were available to speciate total Hg into the elemental and organic forms.
11/98
Solid Waste Disposal
2.4-11
-------
Table 2.4-2. DEFAULT CONCENTRATIONS OF BENZENE, NMOC, AND TOLUENE BASED ON WASTE
DISPOSAL HISTORY2
(SCC 50100402, 50300603)
Pollutant
Benzene*5
Co-disposal
No or Unknown co-disposal
NMOC (as hexane)c
Co-disposal
No or Unknown co-disposal
Tolueneb
Co-disposal
No or Unknown co-disposal
Molecular
Weight
78.11
86.18
92.13
Default
Concentration
(ppmv)
11.1
1.91
2420
595
165
39.3
Emission Factor
Rating
D
B
D
B
D
A
a References 10-54. Source Classification Codes in parentheses.
b Hazardous Air Pollutants listed in Title III of the 1990 Clean Air Act Amendments.
c For NSPS/Emission Guideline compliance purposes, the default concentration for NMOC as
specified in the final rule must be used. For purposes not associated with NSPS/Emission
Guideline compliance, the default VOC content at co-disposal sites = 85 percent by weight
(2,060 ppmv as hexane); at No or Unknown sites = 39 percent by weight 235 ppmv as hexane).
2.4-12
EMISSION FACTORS
11/98
-------
Table 2.4-3. CONTROL EFFICIENCIES FOR LFG CONSTITUENTS3
Control Device
Boiler/Steam Turbine
(50100423)
Flarec
(50100410)
(50300601)
Gas Turbine
(50100420)
1C Engine
(50100421)
Constituent*5
NMOC
Halogenated Species
Non-Halogenated Species
NMOC
Halogenated Species
Non-Halogenated Species
NMOC
Halogenated Species
Non-Halogenated Species
NMOC
Halogenated Species
Non-Halogenated Species
Control Efficiency (%)
Typical Range Rating
98.0
99.6
99.8
99.2
98.0
99.7
94.4
99.7
98.2
97.2
93.0
86.1
96-99+
87-99+
67-99+
90-99+
91-99+
38-99+
90-99+
98-99+
97-99+
94-99+
90-99+
25-99+
D
D
D
B
C
C
E
E
E
E
E
E
a References 10-67. Source Classification Codes in parentheses.
b Halogenated species are those containing atoms of chlorine, bromine, fluorine, or iodine. For any
equipment, the control efficiency for mercury should be assumed to be 0. See section 2.4.4.2 for
methods to estimate emissions of SO2, CO2, and HC1.
c Where information on equipment was given in the reference, test data were taken from enclosed flares.
Control efficiencies are assumed to be equally representative of open flares.
11/98
Solid Waste Disposal
2.4-13
-------
Table 2.4-4. (Metric Units) EMISSION FACTORS FOR SECONDARY COMPOUNDS
EXITING CONTROL DEVICES1
Control Device
Flarec
(50100410)
(50300601)
1C Engine
(50100421)
Boiler/Steam Turbined
(50100423)
Gas Turbine
(50100420)
Pollutantb
Nitrogen dioxide
Carbon monoxide
Paniculate matter
Nitrogen dioxide
Carbon monoxide
Particulate matter
Nitrogen dioxide
Carbon monoxide
Particulate matter
Nitrogen dioxide
Carbon monoxide
Particulate matter
kg/106 dscm
Methane
650
12,000
270
4,000
7,500
770
530
90
130
1,400
3,600
350
Emission Factor
Rating
C
C
D
D
C
E
D
E
D
D
E
E
a Source Classification Codes in parentheses. Divide kg/106 dscm by 16,700 to obtain kg/hr/dscmm.
b No data on PM size distributions were available, however for other gas-fired combustion sources, most
of the particulate matter is less than 2.5 microns in diameter. Hence, this emission factor can be used to
provide estimates of PM-10 or PM-2.5 emissions. See section 2.4.4.2 for methods to estimate CO2,
SO2, and HC1.
c Where information on equipment was given in the reference, test data were taken from enclosed flares.
Control efficiencies are assumed to be equally representative of open flares.
All source tests were conducted on boilers, however emission factors should also be representative of
steam turbines. Emission factors are representative of boilers equipped with low-NOx burners and flue
gas recirculation. No data were available for uncontrolled NOX emissions.
2.4-14
EMISSION FACTORS
11/98
-------
Table 2.4-5. (English Units) EMISSION RATES FOR SECONDARY COMPOUNDS
EXITING CONTROL DEVICES3
Control Device
Flarec
(50100410)
(50300601)
1C Engine
(50100421)
Boiler/Steam Turbined
(50100423)
Gas Turbine
(50100420)
Pollutant*3
Nitrogen dioxide
Carbon monoxide
Particulate matter
Nitrogen dioxide
Carbon monoxide
Particulate matter
Nitrogen dioxide
Carbon monoxide
Particulate matter
Nitrogen dioxide
Carbon monoxide
Particulate matter
lb/106 dscf
Methane
40
750
17
250
470
48
33
5.7
8.2
87
230
22
Emission
Factor Rating
C
C
D
D
C
E
E
E
E
D
D
E
a Source Classification Codes in parentheses. Divide lb/106 dscf by 16,700 to obtain Ib/hr/dscfm.
b Based on data for other combustion sources, most of the paniculate matter will be less than 2.5
microns in diameter. Hence, this emission rate can be used to provide estimates of PM-10 or
PM-2.5 emissions. See section 2.4.4.2 for methods to estimate CO2, SO2, and HC1.
c Where information on equipment was given in the reference, test data were taken from enclosed
flares. Control efficiencies are assumed to be equally representative of open flares.
d All source tests were conducted on boilers, however emission factors should also be
representative of steam turbines. Emission factors are representative of boilers equipped with
low-NOx burners and flue gas recirculation. No data were available for uncontrolled NOX
emissions.
References for Section 2.4
1. "Criteria for Municipal Solid Waste Landfills," 40 CFR Part 258, Volume 56, No. 196, October 9,
1991.
2. Air Emissions from Municipal Solid Waste Landfills - Background Information for Proposed
Standards and Guidelines, Office of Air Quality Planning and Standards, EPA-450/3-90-011a,
Chapters 3 and 4, U. S. Environmental Protection Agency, Research Triangle Park, NC, March 1991.
3. Characterization of Municipal Solid Waste in the United States: 1992 Update, Office of Solid Waste,
EPA-530-R-92-019, U. S. Environmental Protection Agency, Washington, DC, NTIS
No. PB92-207-166, July 1992.
4. Eastern Research Group, Inc., List of Municipal Solid Waste Landfills, Prepared for the
U. S. Environmental Protection Agency, Office of Solid Waste, Municipal and Industrial Solid Waste
Division, Washington, DC, September 1992.
5. Suggested Control Measures for Landfill Gas Emissions, State of California Air Resources Board,
Stationary Source Division, Sacramento, CA, August 1990.
11/98 Solid Waste Disposal 2.4-15
-------
6. "Standards of Performance for New Stationary Sources and Guidelines for Control of Existing Sources:
Municipal Solid Waste Landfills; Proposed Rule, Guideline, and Notice of Public Hearing," 40 CFR
Parts 51, 52, and 60, Vol. 56, No. 104, May 30, 1991.
7. S.W. Zison, Landfill Gas Production Curves: Myth Versus Reality, Pacific Energy, City of Commerce,
CA, [Unpublished]
8. R.L. Peer, et al., Memorandum Methodology Used to Revise the Model Inputs in the Municipal Solid
Waste Landfills Input Data Bases (Revised), to the Municipal Solid Waste Landfills Docket No. A-88-
09, April 28, 1993.
9. A.R. Chowdhury, Emissions from a Landfill Gas-Fired Turbine/Generator Set, Source Test Report
C-84-33, Los Angeles County Sanitation District, South Coast Air Quality Management District, June
28, 1984.
10. Engineering-Science, Inc., Report of Stack Testing at County Sanitation District Los Angeles Puente
Hills Landfill, Los Angeles County Sanitation District, August 15, 1984.
11. J.R. Manker, Vinyl Chloride (and Other Organic Compounds) Content of Landfill Gas Vented to an
Inoperative Flare, Source Test Report 84-496, David Price Company, South Coast Air Quality
Management District, November 30, 1984.
12. S. Mainoff, Landfill Gas Composition, Source Test Report 85-102, Bradley Pit Landfill, South Coast
Air Quality Management District, May 22, 1985.
13. J. Littman, Vinyl Chloride and Other Selected Compounds Present in A Landfill Gas Collection
System Prior to and after Flaring, Source Test Report 85-369, Los Angeles County Sanitation District,
South Coast Air Quality Management District, October 9, 1985.
14. W.A. Nakagawa, Emissions from a Landfill Exhausting Through a Flare System, Source Test Report
85-461, Operating Industries, South Coast Air Quality Management District. October 14, 1985.
15. S. Marinoff, Emissions from a Landfill Gas Collection System, Source Test Report 85-511. Sheldon
Street Landfill, South Coast Air Quality Management District, December 9, 1985.
16. W.A. Nakagawa, Vinyl Chloride and Other Selected Compounds Present in a Landfill Gas Collection
System Prior to and after Flaring, Source Test Report 85-592, Mission Canyon Landfill, Los Angeles
County Sanitation District, South Coast Air Quality Management District, January 16, 1986.
17. California Air Resources Board, Evaluation Test on a Landfill Gas-Fired Flare at the BKK Landfill
Facility, West Covina, CA, ARB-SS-87-09, July 1986.
18. S. Marinoff, Gaseous Composition from a Landfill Gas Collection System and Flare, Source Test
Report 86-0342, Syufy Enterprises, South Coast Air Quality Management District, August 21,1986.
19. Analytical Laboratory Report for Source Test, Azusa Land Reclamation, June 30, 1983, South Coast
Air Quality Management District.
20. J.R. Manker, Source Test Report C-84-202, Bradley Pit Landfill, South Coast Air Quality Management
District, May 25, 1984.
21. S. Marinoff, Source Test Report 84-315, Puente Hills Landfill, South Coast Air Quality Management
District, February 6,1985.
22. P.P. Chavez, Source Test Report 84-596, Bradley Pit Landfill, South Coast Air Quality Management
District, March 11, 1985.
2.4-16 EMISSION FACTORS 11/98
-------
23. S. Marinoff, Source Test Report 84-3 73, Los Angeles By-Products, South Coast air Quality
Management District, March 27, 1985.
24. J. Littman, Source Test Report 85-403, Palos Verdes Landfill, South Coast Air Quality Management
District, September 25, 1985.
25. S. Marinoff, Source Test Report 86-0234, Pacific Lighting Energy Systems, South Coast Air Quality
Management District, July 16, 1986.
26. South Coast Air Quality Management District, Evaluation Test on a Landfill Gas-Fired Flare at the
Los Angeles County Sanitation District's Puente Hills Landfill Facility, [ARB/SS-87-06],
Sacramento, CA, July 1986.
27. D.L. Campbell, et al., Analysis of Factors Affecting Methane Gas Recovery from Six Landfills, Air
and Energy Engineering Research Laboratory, EPA-600/2-91-055, U. S. Environmental Protection
Agency, Research Triangle Park, NC, September 1991.
28. Browning-Ferris Industries, Source Test Report, Lyon Development Landfill, August 21, 1990.
29. X.V. Via, Source Test Report, Browning-Ferris Industries, Azusa Landfill.
30. M. Nourot, Gaseous Composition from a Landfill Gas Collection System and Flare Outlet. Laidlaw
Gas Recovery Systems, to J.R. Farmer, OAQPS:ESD, December 8, 1987.
31. D. A. Stringham and W.H. Wolfe, Waste Management of North America, Inc., to J.R. Farmer,
OAQPS:ESD, January 29, 1988, Response to Section 114 questionnaire.
32. V. Espinosa, Source Test Report 87-0318, Los Angeles County Sanitation District Calabasas Landfill,
South Coast Air Quality Management District, December 16, 1987.
33. C.S. Bhatt, Source Test Report 87-0329, Los Angeles County Sanitation District, Scholl Canyon
Landfill, South Coast Air Quality Management District, December 4, 1987.
34. V. Espinosa, Source Test Report 8 7-0391, Puente Hills Landfill, South Coast Air Quality Management
District, February 5, 1988.
35. V. Espinosa, Source Test Report 87-0376, Palos Verdes Landfill, South Coast Air Quality Management
District, February 9, 1987.
36. Bay Area Air Quality Management District, Landfill Gas Characterization, Oakland, CA, 1988.
37. Steiner Environmental, Inc., Emission Testing at BFI's Arbor Hills Landfill, Northville, Michigan,
September 22 through 25, 1992, Bakersfield, CA, December 1992.
38. PEI Associates, Inc., Emission Test Report - Performance Evaluation Landfill-Gas Enclosed Flare,
Browning Ferris Industries, Chicopee, MA, 1990.
39. Kleinfelder Inc., Source Test Report Boiler and Flare Systems, Prepared for Laidlaw Gas Recovery
Systems, Coyote Canyon Landfill, Diamond Bar, CA, 1991.
40. Bay Area Air Quality Management District, McGill Flare Destruction Efficiency Test Report for
Landfill Gas at the Durham Road Landfill, Oakland, CA, 1988.
41. San Diego Air Pollution Control District, Solid Waste Assessment for Otay Valley/Annex Landfill. San
Diego, CA, December 1988.
11/98 Solid Waste Disposal 2.4-17
-------
42. PEI Associates, Inc., Emission Test Report - Performance Evaluation Landfill Gas Enclosed Flare,
Rockingham, VT, September 1990.
43. Browning-Ferris Industries, Gas Flare Emissions Source Test for Sunshine Canyon Land/ill. Sylmar,
CA, 1991.
44. Scott Environmental Technology, Methane and Nonmethane Organic Destruction Efficiency Tests of
an Enclosed Landfill Gas Flare, April 1992.
45. BCM Engineers, Planners, Scientists and Laboratory Services, Air Pollution Emission Evaluation
Report for Ground Flare at Browning Ferris Industries Greentree Landfill, Kersey, Pennsylvania.
Pittsburgh, PA, May 1992.
46. EnvironMETeo Services Inc., Stack Emissions Test Report for Ameron Kapaa Quarry, Waipahu, HI,
January 1994.
47. Waukesha Pearce Industries, Inc., Report of Emission Levels and Fuel Economies for Eight Waukesha
12V-AT25GL Units Located at the Johnston, Rhode Island Central Landfill, Houston TX, July 19,
1991.
48. Mostardi-Platt Associates, Inc., Gaseous Emission Study Performed for Waste Management of North
America, Inc., CID Environmental Complex Gas Recovery Facility, August 8, 1989. Chicago, EL,
August 1989.
49. Mostardi-Platt Associates, Inc., Gaseous Emission Study Performed for Waste Management of North
America, Inc., at the CID Environmental Complex Gas Recovery Facility, July 12-14, 1989. Chicago,
EL, July 1989.
50. Browning-Ferris Gas Services, Inc., Final Report for Emissions Compliance Testing of One Waukesha
Engine Generator, Chicopee, MA, February 1994.
51. Browning-Ferris Gas Services, Inc., Final Report for Emissions Compliance Testing of Three
Waukesha Engine Generators, Richmond, VA, February 1994.
52. South Coast Environmental Company (SCEC), Emission Factors for Landfill Gas Flares at the
Arizona Street Landfill, Prepared for the San Diego Air Pollution Control District, San Diego, CA,
November 1992.
53. Camot, Emission Tests on the Puente Hills Energy from Landfill Gas (PERG) Facility - Unit 400,
September 1993, Prepared for County Sanitation Districts of Los Angeles County, Tustin, CA,
November 1993.
54. Pape & Steiner Environmental Services, Compliance Testing for Spadra Landfill Gas-to-Energy
Plant, July 25 and 26, 1990, Bakersfield, CA, November 1990.
55. AB2588 Source Test Report for Oxnard Landfill, July 23-27,1990, by Petro Chem Environmental
Services, Inc., for Pacific Energy Systems, Commerce, CA, October 1990.
56. AB2588 Source Test Report for Oxnard Landfill, October 16,1990, by Petro Chem Environmental
Services, Inc., for Pacific Energy Systems, Commerce, CA, November 1990.
57. Engineering Source Test Report for Oxnard Landfill, December 20,1990, by Petro Chem
Environmental Services, Inc., for Pacific Energy Systems, Commerce, CA, January 1991.
58. AB2588 Emissions Inventory Report for the Salinas Crazy Horse Canyon Landfill, Pacific Energy,
Commerce, CA, October 1990.
2.4-18 EMISSION FACTORS 11/98
-------
59. Newby Island Plant 2 Site 1C Engine's Emission Test, February 7-8, 1990, Laidlaw Gas Recovery
Systems, Newark, CA, February 1990.
60. Landfill Methane Recovery Part II: Gas Characterization, Final Report, Gas Research Institute,
December 1982.
61. Letter from J.D. Thornton, Minnesota Pollution Control Agency, to R. Myers, U.S. EPA, February 1,
1996.
62. Letter and attached documents from M. Sauers, GSF Energy, to S. Thorneloe, U.S. EPA, May 29,1996.
63. Landfill Gas Paniculate and Metals Concentration and Flow Rate, Mountaingate Landfill Gas Recovery
Plant, Horizon Air Measurement Services, prepared for GSF Energy, Inc., May 1992.
64. Landfill Gas Engine Exhaust Emissions Test Report in Support of Modification to Existing 1C Engine
Permit at Bakersfield Landfill Unit #1, Pacific Energy Services, December 4, 1990.
65. Addendum to Source Test Report for Superior Engine #1 at Otay Landfill, Pacific Energy Services,
April 2, 1991.
66. Source Test Report 88-0075 of Emissions from an Internal Combustion Engine Fueled by Landfill Gas,
Penrose Landfill, Pacific Energy Lighting Systems, South Coast Air Quality Management District,
February 24, 1988.
67. Source Test Report 88-0096 of Emissions from an Internal Combustion Engine Fueled by Landfill Gas,
Toyon Canyon Landfill, Pacific Energy Lighting Systems, March 8, 1988.
68. Letter and attached documents from C. Nesbitt, Los Angeles County Sanitation Districts, to K. Brust,
E.H. Pechan and Associates, Inc., December 6,1996.
69. Determination of Landfill Gas Composition and Pollutant Emission Rates at Fresh Kills Landfill,
revised Final Report, Radian Corporation, prepared for U.S. EPA, November 10, 1995.
70. Advanced Technology Systems, Inc., Report on Determination of Enclosed Landfill Gas Flare
Performance, Prepared for Y & S Maintenance, Inc., February 1995.
71. Chester Environmental, Report on Ground Flare Emissions Test Results, Prepared for Seneca Landfill,
Inc., October 1993.
72. Smith Environmental Technologies Corporation, Compliance Emission Determination of the Enclosed
Landfill Gas Flare and Leachate Treatment Process Vents, Prepared for Clinton County Solid Waste
Authority, April 1996.
73. AirRecon®, Division of RECON Environmental Corp., Compliance Stack Test Report for the Land/ill
Gas FLare Met & Outlet at Bethlehem Landfill, Prepared for LFG Specialties Inc., December 3, 1996.
74. ROJAC Environmental Services, Inc., Compliance Test Report, Hartford Landfill Flare Emissions
Test Program, November 19, 1993.
75. Normandeau Associates, Inc., Emissions Testing of a Landfill Gas Flare at Contra Costa Land/ill,
Antioch, California, March 22, 1994 and April 22, 1994, May 17, 1994.
76. Roe, S.M., et. al., Methodologies for Quantifying Pollution Prevention Benefits from Landfill Gas
Control and Utilization, Prepared for U.S. EPA, Office of Air and Radiation, Air and Energy
Engineering Laboratory, EPA-600/R-95-089, July 1995.
11/98 Solid Waste Disposal 2.4-19
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10.6.1 Waferboard/Oriented Strandboard Manufacturing
10.6.1.1 General1
Waferboard (WB) and oriented strandboard (OSB) belong to the subset of reconstituted wood panel
products called flakeboards. They are structural panels made from wood wafers specially produced from logs
at the plant. When waferboard was developed in the 1950s, the wafers were not intentionally oriented.
However, by 1989 most waferboard plants were producing oriented waferboard (OWE). Oriented
strandboard originated in the early 1980s. The relatively long and narrow flakes (strands) are blended with
resin and formed into a 3- or 5-layered mat. Aligning the strands in each layer perpendicular to adjacent
layers gives OSB flexural properties superior to those of randomly oriented waferboard. Oriented
waferboard and OSB are suitable for markets in which softwood plywood still dominates. They are chiefly
used as sheathing, single-layer flooring, and underlayment in light-frame construction.
10.6.1.2 Process Description1"3
Figure 10.6.1-1 presents a typical process flow diagram for a WB/OSB plant. WB/OSB
manufacturing begins with whole logs, which are cut to 254-cm (100-in.) lengths by a slasher saw. In
northern plants, these logs are put in hot ponds maintained at a temperature between 18 and 43°C (80° and
120°F). This pretreatment prepares the logs for the waferizer by thawing them during winter operations.
The logs then are debarked and carried to stationary slasher saws, where they are cut into 84-cm (33-in.)
lengths, called bolts, in preparation for the waferizer. Some mills do not slash debarked logs into bolts, but
instead feed whole debarked logs into the waferizer. The waferizer slices the logs into wafers approximately
3.8 cm (1.5 in.) wide by 7.6 cm (3 in.) long by 0.07 cm (0.028 in.) thick. The wafers may pass through green
screens to remove fines and differentiate core and surface material, or they may be conveyed directly to wet
wafer storage bins to await processing through the dryers.
Triple-pass rotary drum dryers are typical in WB/OSB plants. The dryers are normally fired with
wood residue from the plant, but occasionally oil or natural gas also are used as fuels. The wafers are dried to
a low moisture content (generally 4 to 10 percent, dry basis) to compensate for moisture gained by adding
resins and other additives. Generally, dryers are dedicated to drying either core or surface material to allow
independent adjustment of moisture content. This independent adjustment is particularly important where
different resins are used in core and surface materials.
After drying, the dried wafers are conveyed pneumatically from the dryer, separated from the gas *
stream at the primary cyclone, and screened to remove fines (which absorb too much resin) and to separate
the wafers by surface area and weight. The gas stream continues through an air pollution control device and
is emitted to the atmosphere. Undersized material is sent to a storage area for use as fuel for dryer burners or
boilers. The screened wafers are stored in dry bins.
The dried wafers then are conveyed to the blender, where they are blended with resin, wax, and other
additives. The most commonly used binders are thermosetting urea-formaldehyde, phenol-formaldehyde, and
isocyanate resins, all of which require the application of heat for curing. From the blender the resinated
wafers are conveyed to the former, where they are metered out on a continuously moving screen system. The
mat forming process is the only step in the manufacturing process in which there is any significant difference
between WB and OSB production. In WB production, the wafers are allowed to fall randomly to the moving
screen below to form a mat of the required thickness. In OSB production, the wafers are oriented
electrostatically or mechanically in one direction as they fall to the screen below. Subsequent forming heads
12/98 Wood Products Industry 10.6.1-1
-------
form distinct layers in which the wafers are oriented perpendicular to those in the previous layer. The
alternating oriented layers result in a structurally superior panel.
In the mat trimming section, the continuous formed mat is cut into desired lengths by a traveling saw.
The trimmed mat then is passed to the accumulating press loader and sent to the hot press. The press applies
heat and pressure to activate the resin and bond the wafers into a solid reconstituted product. In most hot
presses, heat is provided by steam generated by a boiler that burns plant residuals. Hot oil and hot water also
can be used to heat the press. After cooling, the bonded panel is trimmed to final dimensions, finished (if
necessary), and the product is packaged for shipment.
10.6.1.3 Emissions And Controls1"55
The primary emission sources at WB/OSB mills are wafer dryers and hot press vents. Other
emission sources may include boilers, log debarking, sawing, waferizing, blending, forming, board cooling,
and finishing operations such as sanding, trimming, and edge painting. Other potential emissions sources
ancillary to the manufacturing process may include wood chip storage piles and bins (including wood fuel),
chip handling systems, and resin storage and handling systems.
Operations such as log debarking, sawing, and waferizing, in addition to chip piles and bins, and chip
handling systems generate paniculate matter (PM) and PM less than 10 micrometers in aerodynamic diameter
(PM-10) emissions in the form of sawdust and wood particles.
Emissions from dryers that are exhausted from the primary recovery cyclone include wood dust and
other solid PM, volatile organic compounds (VOCs), condensible PM, and products of combustion such as
carbon monoxide (CO), carbon dioxide (CQ), and nitrogen oxides (NC^), if direct-fired units are used. The
condensible PM and a portion of the VOCs leave the dryer stack as vapor but condense at normal
atmospheric temperatures to form liquid particles or mist that creates a visible blue haze. Both the VOCs and
condensible PM are primarily compounds evaporated from the wood, with a minor constituent being
combustion products. Quantities emitted are dependent on wood species, dryer temperature, fuel used, and
other factors including season of the year, time between logging and processing, and wafer storage time.
Calculating PM-10 emissions from the wood products industries is problematic due to the
relationship between PM-10 (or PM) emissions and VOC emissions from these processes. Because the
Method 201A train (PM-10) operates with an in-stack cyclone and filter, organic materials that are volatile at
stack gas temperatures but that are condensed at back half impinger temperatures {-20°C [~68°F]) are
collected as condensible PM-10. However, these materials will also be measured as VOC via Methods 25
and 25 A, which operate with a heated or an in-stack filter. Hence, if PM-10 is calculated as the sum of
filterable and condensible material, some pollutants will be measured as both PM-10 and VOC emissions.
However, if only filterable material is considered to be PM-10, the PM-10 emission factors will be highly
dependent on stack gas temperature. In this AP-42 section, PM-10 is reported as front half catch only
(Method 201A results only; not including Method 202 results). However, condensible PM results are also
reported, and these results can be combined with the PM-10 results as appropriate for a specific application.
Measured VOC emissions may be affected by the sampling method and by the quantity of formaldehyde and
other aldehydes and ketones in the exhaust; formaldehyde is not quantified using Method 25A. Other low
molecular weight oxygenated compounds have reduced responses to Method 25A. Therefore, when VOC
emissions are measured using Method 25A, the emission rates will be biased low if low molecular weight
oxygenated compounds are present in significant concentrations in the exhaust stream. A more extensive
discussion of these sampling and analysis issues is provided in the Background Report for this section.
10.6.1-2 EMISSION FACTORS 12/98
-------
Emissions from board hot presses are dependent on the type and amount of resin used to bind the
wood particles together, as well as wood species, wood moisture content, wax and catalyst application rates,
and press conditions. When the press opens, vapors that may include resin ingredients such as formaldehyde,
phenol, methylene diphenyl diisocyanate (MDI), and other VOCs are released. The rate at which
formaldehyde is emitted during pressing and board cooling operations is a function of the amount of excess
formaldehyde in the resin, board thickness, press temperature, press cycle time, and catalyst application rates.
Only limited data are available on emissions of the organic constituents included in the exhaust
streams from WB/OSB dryers and presses. However, speciated organic emission data for particleboard and
medium density fiberboard (MDF) may provide an indication of the types of organic compounds emitted
from WB/OSB dryers and presses. Emission factors for speciated organic emissions from particleboard and
MDF dryers and presses are included in AP-42 Sections 10.6.2 and 10.6.3, respectively.
Emissions from finishing operations for WB/OSB products are dependent on the type of products
being finished. For most WB/OSB products, finishing involves trimming to size and possibly painting or
coating the edges. Trimming and sawing operations are sources of PM and PM-10 emissions. No data
specific to WB/OSB panel trimming or sawing are available. However, emission factors for general sawing
operations may provide an order of magnitude estimate for similar WB/OSB sawing and trimming
operations, bearing in mind that the sawing of dry OSB panels may result in greater PM and PM-10
emissions than the sawing of green lumber. It is expected that water-based coatings are used to paint
WB/OSB edges, and the resultant VOC emissions are relatively small.
PM and PM-10 emissions from log debarking, sawing, and waferizing operations can be controlled
through capture in an exhaust system connected to a sized cyclone and/or fabric filter collection system.
Emissions of PM and PM-10 from final trimming operations can be controlled using similar methods. These
wood dust capture and collection systems are used not only to control atmospheric emissions, but also to
collect the dust as a by-product fuel for a boiler or dryer.
Electrostatic control devices provide highly efficient control of PM and PM-10, but lesser control of
condensible organic pollutants in the exhaust streams from dryers. Two devices commonly used to control
emissions from dryers are the electrified filter bed (EFB) and the wet electrostatic precipitator (WESP). The
EFB is a popular PM control device in the wood products industry for controlling dryer exhaust gases
because it is a dry type of control that produces an effluent stream that requires no further treatment. These
units also are relatively small and do not require a large amount of floor space. The EFB is effective at solid
PM removal but not as efficient at removing condensible aerosols in that it cannot remove any material it
cannot condense. Also, the sticky liquid particles generated by drying softwoods cause the EFB to require
frequent maintenance.
WESPs are used on effluent gas streams containing sticky, condensible hydrocarbon pollutants.
Gases exiting the dryer enter a prequench to cool and saturate the gases before they enter the WESP. The
prequench is essentially a low-energy scrubber that sprays water into the incoming gas stream. Some fraction
of the highly water soluble compounds, such as formaldehyde and methanol, may be scrubbed by the
prequench and collected. The gas that exits the prequench is nearly saturated; therefore, further cooling in the
precipitator will condense and capture more of the condensible hydrocarbons, mainly the sticky resins. The
WESP collects only particles and droplets that can be electrostatically charged; vaporous components of the
gas stream that do not condense are not collected by the device. One disadvantage of the WESP is that it
generates a wastewater effluent. Because OSB mills are generally designated as zero discharge facilities, they
must treat their own spray water and/or consume it internally. Mills that operate boilers or other wet cell
burners can apply some of the spent spray water to the fuel. Some or all of the remaining spray water may be
used as makeup water in hot ponds or in debarkers for dust control.
12/98 Wood Products Industry 10.6.1-3
-------
A VOC control technology gaining popularity in the wood products industry for controlling both
dryer and press exhaust gases is regenerative thermal oxidation. Thermal oxidizers destroy VOCs, CO, and
condensible organics by burning them at high temperatures. Regenerative thermal oxidizers (RTOs) are
designed to preheat the inlet emission stream with heat recovered from the incineration exhaust gases. Up to
98 percent heat recovery is possible, although 95 percent is typically specified. Gases entering an RTO are
heated by passing through preheated beds packed with a ceramic media. A gas burner brings the preheated
emissions up to an incineration temperature between 78S and 871 °C (1450° and 1600°F) in a combustion
chamber with sufficient gas residence time to complete the combustion. Combustion gases then pass through
a cooled ceramic bed where heat is extracted. By reversing the flow through the beds, the heat transferred
from the combustion exhaust air preheats the incoming gases to be treated, thereby reducing auxiliary fuel
requirements.
Another control technology drawing the attention of the WB/OSB industry is biological air filtration,
or biofiltration. Biofiltration systems can be used effectively for control of a variety of pollutants including
organic compounds (including formaldehyde and benzene), NO, CO, and PM from both dryer and press
exhaust streams. In biofiltration, exhaust streams are vented through a moist bed of composted wood bark or
other biologically active material. Pollutants are adsorbed from the exhaust stream onto the filter media and
converted by microbiological degradation to CO,, water, and inorganic salts. Typical biofilter design
consists of a three- to six-foot deep bed of media suspended over an air distribution plenum. Exhaust gases
entering the plenum are evenly distributed through the moist biofilter media.
Another promising technology for the control of OSB dryer VOC and CO emissions is exhaust gas
recycle. This technology uses an oversized combustion unit that can accommodate 100 percent recirculation
of dryer exhaust gases. The recirculated dryer exhaust is mixed with combustion air and exposed directly to
the burner flame. VOC emissions from burner combustion are incinerated in the second stage of the unit.
High temperature exhaust from the combustion unit passes through a heat exchanger, which provides heat for
dryer inlet air, and then through an add-on device for PM emission control.
Other potential control technologies for OSB dryers and presses include regenerative catalytic
oxidation (RCO), and absorption systems (scrubbers).
Fugitive emissions from road dust and uncovered bark and dust storage piles may be controlled in a
number of different ways. These methods include enclosure, wet suppression systems, and chemical
stabilization. Control techniques for these sources are discussed more fully in AP-42 Chapter 13,
Miscellaneous Sources.
Table 10.6.1-1 presents emission factors for dryer emissions of PM, including filterable PM,
filterable PM-10, and condensible PM. Table 10.6.1-2 presents an emission factor for dryer emissions of
chromium. Table 10.6.1-3 presents emission factors for dryer emissions of SQ, NOX, CO, and CO2.
Table 10.6.1-4 presents emission factors for dryer emissions of VOC and speciated organic pollutants.
Table 10.6.1-5 presents emission factors for press emissions of PM, including filterable PM, filterable
PM-10, and condensible PM. Table 10.6.1-6 presents emission factors for press emissions of SQ, NOX,
CO, and CO2. Table 10.6.1-7 presents emission factors for press emissions of VOC and speciated organic
compounds.
10.6.1-4 EMISSION FACTORS 12/98
-------
Emission factors for mixed hardwood and softwood species are not reported in this section.
Emission factors for specific mixes of wood species may be calculated by combining emission factors for
individual wood species in the ratio specific to a given application, as emission data for those species become
available. For example, an uncontrolled VOC emission factor for a direct wood-fired rotary dryer processing
60 percent pines and 40 percent hardwoods may be calculated using the uncontrolled VOC emission factors
for pines (8.6 Ib/ODT) and hardwoods (1.6 Ib/ODT), and the ratio of 60 percent to 40 percent. The resultant
emission factor, rounded to two significant figures, would be 5.8 Ib/ODT.
12/98 Wood Products Industry 10.6.1-5
-------
(T) PM EMISSIONS
GASEOUS EMISSIONS
WASTE
RECYCLE
Figure 10.6.1-1. Typical process flow diagram for a waferboard/oriented strandboard plant.
10.6.1-6 EMISSION FACTORS 12/98
-------
Table 10.6.1-1. EMISSION FACTORS FOR OSB DRYERS--PARTICULATE MATTER3
Source
Emission
Control
Devicec
Filterableb
PM
EMISSION
FACTOR
RATING
PM-10
EMISSION
FACTOR
RATING
Condensibled
EMISSION
FACTOR
RATING
Rotary dryer, direct wood-fired
Unspecified pines
(SCC 3-07-010-01)
Aspen
(SCC 3-07-010-08)
Hardwoods
(SCC 3-07-010-10)
Nonee
MCLO
EFB
WESP
RTO
EFB
None6 .
MCLO
EFB
WESP
RTO
3.9f
2.18
0.61m
0.20f
0.17"
l.lm
ND
6.9P
0.92r
0.20'
0.036U
D
C
D
E
D
D
D
C
D
E
ND
2.5h'J
ND
ND
ND
1.2m
ND
ND
1.0m
ND
ND
C
D
D
1.9f
0.4 lk
0.49m
0.83f
0.12"
0.35m
1.9U
0.509
0.40s
0.30'
0.12U
D
B
D
E
D
D
E
D
C
D
E
d
e
f
g
h
j
k
m
n
P
q
r
s
t
Emission factor units are pounds of pollutant per oven-dried ton of wood material out of dryer (Ib/ODT).
One Ib/ODT = 0.5 kg/Mg (oven-dried). Factors represent uncontrolled emissions unless otherwise noted.
SCC = Source Classification Code. ND = no data available.
Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent) sampling
train. Filterable PM-10 is that PM collected on the filter, or in the sample line between the cyclone and
filter of an EPA Method 201 or 201A sampling train.
Emission control device: MCLO = multiclone; EFB = electrified filter bed; WESP = wet electrostatic
precipitator; RTO = regenerative thermal oxidizer.
Condensible PM is that PM collected in the impinger portion of a PM sampling train.
Cyclones are used as product recovery devices and are not considered to be emission control equipment.
References 15-16.
References 6-9.
Multiclones are used for PM; effects on PM-10 are considered negligible.
References 4,7-9.
References 4,6-9.
Reference 12.
References 15-16,44.
References 12,43.
Reference 43.
References 12,48,50.
References 12,50.
References 34,38,43.
Reference 38.
12/98
Wood Products Industry
10.6.1-7
-------
Table 10.6.1-2. EMISSION FACTORS FOR OSB DRYERS-CHROMIUM1
Source
Rotary dryer, direct wood-fired
Unspecified pines
(SCC 3-07-010-01)
Emission Control
Device?3
RTO
Emission Factor
0.000063°
EMISSION
FACTOR
RATING
E
a Emission factor units are pounds of pollutant per oven-dried ton of wood material out of dryer (Ib/ODT).
One Ib/ODT = 0.5 kg/Mg (oven-dried). SCC = Source Classification Code.
b Emission control device: RTO = regenerative thermal oxidizer.
c Reference 44.
Table 10.6.1-3. EMISSION FACTORS FOR OSB DRYERS-SOj, NOX, CO, AND CO2a
Source
SO2
EMISSION
FACTOR
RATING
NOX
EMISSION
FACTOR
RATING
CO
EMISSION
FACTOR
RATING
C02
EMISSION
FACTOR
RATING
Rotary dryer, direct wood-fired (3-07-010-01, -08, -10)
Uncontrolled*1
RTOf
ND
0.014«
E
0.65C
0.60h
B
C
5.8d
2.1h
B
C
600e
760>
B
B
Rotary dryer, direct natural gas-fired (3-07-010-20)
Uncontrolled"
ND
0.68k
E
0.72m
D
330"
E
Emission factor units are pounds of pollutant per oven-dried ton of wood material out of dryer (Ib/ODT).
One Ib/ODT = 0.5 kg/Mg (oven-dried). Factors represent uncontrolled emissions unless otherwise noted.
SCC = Source Classification Code. ND = no data available.
Emission controls used are for PM; effects on gaseous emissions are considered negligible.
References 10,12,15-19,23,27,29,38-39,43-44,48,50-52,55.
References 6-8,10,12,15-17,19,23,27,29,34,36,38-39,41,43-44,48,50-52.
References 6-8,10-11,15-19,23,36,38,40-41,43,47-48,50-52,55.
RTO = regenerative thermal oxidizer.
Reference 38.
References 15-17,19,22-23,27,29,38,44.
References 15-17,19,22-23,38,44.
Reference 20.
m References 20,39.
n Reference 39.
10.6.1-8
EMISSION FACTORS
12/98
-------
Table 10.6.1-4. EMISSION FACTORS FOR OSB DRYERS-ORGANICS3
Source
Emission
Control
Device?3
CASRhF
Pollutant
Emission
Factor
EMISSION
FACTOR
RATING
Rotary dryer, direct wood-fired
Unspecified pines
(SCC 3-07-010-01)
Aspen
(SCC 3-07-010-08)
Hardwoods
(SCC 3-07-010-10)
Noned
RTO
Noned
Noned
RTO
50-00-0
50-00-0
50-00-0
50-00-0
71-43-2
50-32-8
108-95-2
50-00-0
voce
Formaldehyde *
voce
Formaldehyde *
voce
Formaldehyde *
voce
Formaldehyde *
Benzene *
Benzo-a-pyrene*
Phenol *
voce
Formaldehyde *
8.6f
0.0678
0.33h
0.034J
2.2k
O.llk
1.6m
0.084"
0.0016P
0.0000030P
0.0050p
0.036q
0.0173
C
D
D
E
D
E
B
D
E
E
E
E
E
Rotary dryer, direct natural gas-fired
Hardwoods
(SCC 3-07-010-20)
Noned
50-00-0
Formaldehyde *
0.036r
E
a Emission factor units are pounds of pollutant per oven-dried ton of wood material out of dryer (Ib/ODT).
One Ib/ODT = 0.5 kg/Mg (oven-dried). Factors represent uncontrolled emissions unless otherwise noted.
SCC = Source Classification Code. * = hazardous air pollutant as listed in Section 112(b) of the Clean
Air Act.
b Emission control device: RTO = regenerative thermal oxidizer.
c CASRN = Chemistry Abstracts Service Registry Number.
d Emission controls used are for PM; effects on gaseous emissions are considered negligible.
Factors for VOC on a propane basis. Formaldehyde has been added.
References 6-9,12,15-16,44.
References 5,7-9,15-16.
References 15-16,44.
References 15-16.
Reference 12.
m References 12,24,34,38,48,50.
n References 12,34,38,43,48,50.
P Reference 43.
q Reference 38.
r Reference 20.
12/98
Wood Products Industry
10.6.1-9
-------
Table 10.6.1-5. EMISSION FACTORS FOR OSB PRESSES-PARTICIPATE MATTER3
Source0
Hot press, PF resin
(SCC 3-07-010-53)
Hot press, MDI resin
(SCC 3-07-010-55)
Hot press, PF/MDI
resins
(SCC 3-07-010-57)
Emission
Control
Deviced
None
None
None
RTO
Filterableb
PM
0.12f
0.1 6«
0.37h
0.049k
EMISSION
FACTOR
RATING
D
D
B
D
PM-10
0.10f
ND
O.llf
ND
EMISSION
FACTOR
RATING
E
E
Condensible6
0.25f
0.046g
0.14J
0.082k
EMISSION
FACTOR
RATING
D
D
B
D
a Emission factor units are pounds of pollutant per thousand square feet of 3/8-inch thick panel
(Ib/MSF 3/8). One Ib/MSF 3/8 = 0.5 kg/m3. Factors represent uncontrolled emissions unless otherwise
noted. SCC = Source Classification Code. ND = no data available.
b Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent) sampling
train. Filterable PM-10 is that PM collected on the filter, or in the sample line between the cyclone and
filter of an EPA Method 201 or 201A sampling train.
c PF = phenol formaldehyde; MDI = methylene diphenyl diisocyanate; PF/MDI = PF resin in surface layers,
MDI resin in core layers.
d Emission control device: RTO = regenerative thermal oxidizer.
e Condensible PM is that PM collected in the impinger portion of a PM sampling train.
f Reference 12.
g References 12,18,24,38.
h References 9,12,21,25-26,30,34-36,39,41-43,45-46.
J References 9,12,21,25-26,30,34-36,39,41-43.
k References 15-17,21,23,25-26,30,35,44.
10.6.1-10
EMISSION FACTORS
12/98
-------
Table 10.6.1-6. EMISSION FACTORS FOR OSB PRESSES--SO2, NOX, CO, AND CO2
Source
SO2
EMISSION
FACTOR
RATING
NOX
EMISSION
FACTOR
RATING
CO
EMISSION
FACTOR
RATING
C02
EMISSION
FACTOR
RATING
Hot press
(SCC 3-07-010-53, -55, -57)
Uncontrolled
RTOf
0.037b
ND
E
0.038C
0.288
D
D
0.1 Od
0.26h
B
D
12e
42J
B
C
a Emission factor units are pounds of pollutant per thousand square feet of 3/8-inch thick panel
(Ib/MSF 3/8). One Ib/MSF 3/8 = 0.5 kg/m3. Factors represent uncontrolled emissions unless otherwise
noted. SCC = Source Classification Code. ND = no data available.
b References 31-32.
c References 12,15-17,23-24,30-33,38.
d References 12,15-17,21,23-24,30-33,38-39,42-43.
e References 15-16,18,21,24-26,31-32,35-36,38-39,41-43,45-52,54.
RTO = regenerative thermal oxidizer.
* References 15-17,23,30,33,35,44.
h References 15-17,21,23,30,33,35,44.
J References 15-17,21,23,35,44.
f
12/98
Wood Products Industry
10.6.1-11
-------
Table 10.6.1-7. EMISSION FACTORS FOR OSB PRESSES-ORGANICS3
Sourceb
Hot press, PF resin
(SCC 3-07-010-53)
Hot press, MDI resin
(SCC 3-07-010-55)
Hot press, PF/MDI resins
(SCC 3-07-010-57)
Emission
Control
Device0
None
None
None
RTO
CASRNd
50-00-0
91-20-3
108-95-2
50-00-0
101-68-8
50-00-0
101-68-8
108-95-2
50-00-0
101-68-8
108-95-2
Pollutant
voce
Formaldehyde *
Naphthalene *
Phenol *
voce
Formaldehyde *
MDI*
voce
Formaldehyde *
MDI*
Phenol *
voce
Formaldehyde *
MDI*
Phenol *
Emission
Factor
0.52f
0.043f
0.0030f
0.053f
0.458
0.064h
0.0017h
0.56J
0.063k
0.0021m
0.019"
0.040P
0.0043^
0.000078r
0.0026s
EMISSION
FACTOR
RATING
D
E
E
E
D
E
E
B
D
D
D
D
E
E
E
Emission factor units are pounds of pollutant per thousand square feet of 3/8-inch thick panel
(Ib/MSF 3/8). One Ib/MSF 3/8 = 0.5 kg/m3. Factors represent uncontrolled emissions unless otherwise
noted. SCC = Source Classification Code. * = hazardous air pollutant as listed in Section 112(b) of the
Clean Air Act.
PF = phenol formaldehyde; MDI = methylene diphenyl diisocyanate; PF/MDI = PF resin in surface layers,
MDI resin in core layers.
Emission control device: RTO = regenerative thermal oxidizer.
CASRN = Chemistry Abstracts Service Registry Number.
Factors for VOC on a propane basis. Formaldehyde has been added.
Reference 12.
References 12,18,24,38.
References 12,38.
References 9,12,15-17,21,23,25-26,30-32,34-36,41,44-52.
References 9,12,15-16,21,31-34,36,41,43,45-48,50-52.
m References 12,21,31-32,34,36,41,45-48,50-52,54.
n References 12,15-16,21,43,45-48,50-52.
P References 15-17,21,23,25-26,30,35,44.
1 References 15-17,21,23,30,33,35.
r References 15-17,21,30,35.
s References 15-16,21,30.
10.6.1-12
EMISSION FACTORS
12/98
-------
References For Section 10.6.1
1. Emission Factor Documentation For AP-42 Section 10.6.1, prepared for the U. S. Environmental
Protection Agency, OAQPS/EFIG, by Midwest Research Institute, Cary, NC, December 1998.
2. C.C. Vaught, Evaluation Of Emission Control Devices At Waferboard Plants , EPA-450/3-90-002,
Control Technology Center, Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC, October 1990.
3. J. G. Haygreen and J. L. Bowyer,Foresf Products And Wood Science: An Introduction, Second
Edition, Iowa State University Press, Ames, IA, 1989.
4. PM-10 Emissions Sampling, Kirby Forest Products, Silsbee, Texas, March 2-5, 1992, prepared for
Louisiana-Pacific Corporation, by Armstrong Environmental, Inc., Project No. W-l 159-92,
March 1992.
5. Formaldehyde Test Results For Press Vents And Dryer Stacks At Louisiana-Pacific Kirby Forest
Industries, Silsbee, Texas, prepared for Environmental Monitoring Laboratories, by Industrial and
Environmental Analysts, Report No. 192-92-35, April 1992.
6. Report Of Air Emissions Tests For Kirby Forest Industries Silsbee OSB Plant, prepared for
Louisiana-Pacific Corporation, by Environmental Monitoring Laboratories, April 1992.
7. Results Of The March 24-28, 1992 EPA-Air Emission Compliance Tests At The Louisiana-Pacific
Plant In Corrigan, Texas, prepared for Louisiana-Pacific Corporation, by Interpoll Laboratories,
Inc., Report No. 2-3532, May 1992.
8. Results Of The March 30 - April 2, 1992 EPA-Air Emission Compliance Tests At The Louisiana-
Pacific Plant In New Waverly, Texas, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 2-3533, May 1992.
9. Results Of The April 4-9, 1992 EPA-Air Emission Compliance Tests At The Louisiana-Pacific
Plant In Urania, Louisiana, prepared for Louisiana-Pacific Corporation, by Interpoll Laboratories,
Inc., Report No. 2-3534, May 1992.
10. Oriented Strand Board Emission Test Report - Weyerhaeuser, Elkin, North Carolina, Volume 1,
prepared for EMB/TSD U. S. Environmental Protection Agency, Research Triangle Park, NC, by
Entropy Environmentalists, Inc., EMB Report 91-WAF-02, April 1992.
11. Source Sampling Report For Georgia-Pacific Corporation - Dudley, North Carolina , prepared for
Georgia-Pacific Corporation, by Environmental Testing, Inc., 1983.
12. Oriented Strandboard And Plywood Air Emission Databases, Technical Bulletin No. 694, the
National Council of the Paper Industry for Air and Stream Improvement, New York, New York,
April 1995.
13. Written communication and attachments from T. A. Crabtree, Smith Engineering Company,
Broomall, PA, to P. E. Lassiter, U. S. Environmental Protection Agency, Research Triangle Park,
NC, July 26, 1996.
12/98 Wood Products Industry 10.6.1-13
-------
14. Technical Memorandum, Minutes of the October 12-13,1993 BACT Technologies Workshop,
Raleigh, NC, sponsored by the American Forest and Paper Association, K. D. Bullock, Midwest
Research Institute, Gary, NC, October 1993.
15. Results Of The July 23-25, 1996 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant, Sagola, Michigan, prepared for Louisiana-Pacific Corporation, by Interpoll Laboratories,
Inc., Report No. 6-8024, August 1996.
16. Letter and attachment from K. Seelig, to L. Kesari, USEPA, Washington, D.C., Correction of VOC
emission rates for July 23-25,1996 test at Louisiana-Pacific Corp., Sagola Michigan, November 5,
1996.
17. Results Of The February 20-22, 1996 EPA And State Air Emission Compliance Testing At The
Louisiana-Pacific Corporation OSB Plant In Hayward, Wisconsin , prepared for Louisiana-Pacific
Corporation, by Interpoll Laboratories, Inc., Report No. 6-7318, March 1996.
18. Revised Results Of The June 21-23, 1994 Air Emission Compliance Tests At The Louisiana-Pacific
Strandboard Plant in Chilco, Idaho, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 4-3191R, August 1994.
19. Results Of The July 12-15, 1994 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant In Hayward, Wisconsin, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 4-3366, August 1994.
20. Results Of The December 7, 1993 Air Emission Compliance Testing At The Louisiana-Pacific OSB
Plant In Tomahawk, Wisconsin, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 3-1854, January 1994.
21. Results Of The April 12 & 13, 1995 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant, Sagola, Michigan, prepared for Louisiana-Pacific Corporation, by Interpoll Laboratories,
Inc., Report No. 5-5194, April 1995.
22. Volatile Organic Compound And Paniculate Emission Testing At Louisiana-Pacific Corporation,
Houlton, Maine, prepared for Louisiana-Pacific Corporation, by Air Pollution Characterization and
Control, Ltd., Project No. 96053, July 1996.
23. Results Of The March 18-21, 1996 EPA And State Air Emission Compliance Testing At The
Louisiana-Pacific OSB Plant In Hayward, Wisconsin, prepared for Louisiana-Pacific Corporation,
by Interpoll Laboratories, Inc., Report No. 6-7451, April 1996.
24. Results Of The May 21 & 22, 1996 Air Emission Compliance Testing At The Louisiana-Pacific
OSB Plant In Two Harbors, Minnesota, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 6-7712, June 1996.
25. Report Of Emissions Testing Of A Regenerative Thermal Oxidizer, Louisiana-Pacific Corp.,
Houlton, Maine, prepared for Louisiana-Pacific Corporation, by TRC Environmental Corporation,
Project No. 18226, May 1995.
10.6.1-14 EMISSION FACTORS 12/98
-------
26. Letter and attachment from S. Somers, to M. Wood and L. Kesari, USEPA, Washington, D.C.,
Revised test method description and PM laboratory data for April 19, 1995 test on press RTO at
Louisiana-Pacific Corp., Houlton, Maine, June 22, 1995.
27. Report Of Air Emissions Tests And VOC Removal Efficiency For Louisiana-Pacific Corp., Urania
OSB Facility, Urania, Louisiana, May 11 & 12, 1995, prepared for Louisiana-Pacific Corporation,
by Environmental Monitoring Laboratories, Inc., July 1995.
28. Report Of Air Emissions Tests For Louisiana-Pacific Corp., New Waverly OSB Facility, New
Waverly, Texas, May 31, And June 1, 1995, prepared for Louisiana-Pacific Corporation, by
Environmental Monitoring Laboratories, Inc., July 1995.
29. Report Of Air Emissions Tests And VOC Removal Efficiency For Louisiana-Pacific Corporation,
Corrigan OSB Facility, Corrigan, Texas, June 2, 1995, prepared for Louisiana-Pacific Corporation,
by Environmental Monitoring Laboratories, Inc., July 1995.
30. Oxidizer Efficiency Sampling, Kirby Forest Products, Silsbee, Texas, July 11-14, 1995 , prepared
for Louisiana-Pacific Corporation, by Armstrong Environmental, Inc., Project No. W-1713-95, July
1995.
31. Air Emissions Compliance Test Report For Louisiana-Pacific, Dungannon, Virginia, Test Dates:
August 30-31, 1995, September 12-13, 1995, prepared for Louisiana-Pacific Corporation, by ETS,
Inc., October 1995.
32. Letter from E. Smith to L. Kesari, USEPA, Washington, D.C., VOC control efficiency calculation for
August 30-31, 1995 test at Louisiana-Pacific Corp., Dungannon, Virginia, December 28, 1995.
33. Emissions Testing Of A Press Regenerative Thermal Oxidizer, Louisiana-Pacific Corporation,
Houlton, Maine, prepared for Louisiana-Pacific Corporation, by TRC Environmental Corporation,
Project No. 19624, January 1996.
34. Report Of Air Emissions Tests For Louisiana-Pacific Corporation, Montrose, Colorado,
December 6 through 8, 1994, prepared for Louisiana-Pacific Corporation, by Environmental
Monitoring Laboratories, January 1995.
35. Results Of The June 7-10, 1994 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant In Hayward, Wisconsin, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 4-3097, August 1994.
36. Results Of The January 25-29, 1993 Air Emission Compliance Tests At The Louisiana-Pacific
Waferboard Plant In Montrose, Colorado, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 3-8023, March 1993.
37. Results Of The July 19&20, 1994 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant In Montrose, Colorado, prepared for Louisiana-Pacific Corporation, by Interpoll Laboratories,
Inc., Report No. 4-3396, August 1994.
38. Results Of The August 27-29, 1996 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant Newberry, Michigan, prepared for Louisiana-Pacific Corporation, by Interpoll Laboratories,
Inc., Report No. 6-8201, October 1996.
12/98 Wood Products Industry 10.6.1-15
-------
39. Results Of The July 11-13, 1995 Air Emission Compliance Tests At The Louisiana-Pacific
Waferboard Plant In Tomahawk, Wisconsin, prepared for Louisiana-Pacific Corporation, by
Interpoll Laboratories, Inc., Report No. 5-6006, July 1995.
40. Louisiana-Pacific Corporation Oriented Strandboard Facility, Fuel Dryer E-Tube Stack,
Montrose, Colorado, October 25, 1994, prepared for Louisiana-Pacific Corporation, by Am Test-
Air Quality, Inc., November 1994.
41. Results Of The March 29-31, 1994 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant In Montrose, Colorado, prepared for Louisiana-Pacific Corporation, by Interpoll Laboratories,
Inc., Report No. 4-2558, April 1994.
42. Results Of The August 23, 1995 Air Emission Compliance Tests At The Louisiana-Pacific
Waferboard Plant In Tomahawk, Wisconsin, prepared for Louisiana-Pacific Corporation, by
Interpoll Laboratories, Inc., Report No. 5-6375, September 1995.
43. Results Of The August 17-19, 1993 Air Emission Compliance Tests At The Louisiana-Pacific
Waferboard Plant In Tomahawk, Wisconsin, prepared for Louisiana-Pacific Corporation, by
Interpoll Laboratories, Inc., Report No. 3-9772, September 1993.
44. Stationary Source Sampling Report, Roxboro OSB Plant, Roxboro, North Carolina, Emissions
Testing For Carbon Monoxide, Chromium, Nitrogen Oxides, Total Hydrocarbons, RTO Nos. 1, 2,
And 3, prepared for Louisiana-Pacific Corporation, by ENTROPY, Inc., Reference No. 15575B,
August 1996.
45. Results Of The June 1993 Air Emission Tests At Two Louisiana-Pacific Waferboard Plants
(Sagola, Michigan and Two Harbors, Minnesota), prepared for Louisiana-Pacific Corporation, by
Interpoll Laboratories, Inc., Report No. 3-9202, September 1993.
46. Data Package For The MDI Samples Collected At The LP/Sagola And LP/Two Harbors Plants On
June 26 & 29, 1993 And Analyzed By Reverse-Phase HPLCAt 254 nm And 275 nm Using
N-p-nitro-benzyl-N-propylamine (Data for Reference No. 45, Report No. 3-9202), prepared for
Louisiana-Pacific Corporation, by Interpoll Laboratories, Inc., November 1993.
47. Results Of The September 21-23, 1993 Air Emission Compliance Tests At The Louisiana-Pacific
Waferboard Plant In Dawson Creek, British Columbia, prepared for Louisiana-Pacific Corporation,
by Interpoll Laboratories, Inc., Report No. 3-1060, November 1993.
48. Results Of The June 8-10, 1993 EPA-Required Air Emission Compliance Tests At The Louisiana-
Pacific Waferboard Plant In Dungannon, Virginia, prepared for Louisiana-Pacific Corporation, by
Interpoll Laboratories, Inc., Report No. 3-9053, July 1993.
49. Air Emissions Compliance Test Report For Louisiana-Pacific Dungannon, Virginia, Test Dates
September 10-11,1996, prepared for Louisiana-Pacific Corporation, by ETS, Inc., October 1996.
50. Results Of The December 14-17, 1993 State-Required Air Emission Compliance Tests At The
Louisiana-Pacific Waferboard Plant In Dungannon, Virginia , prepared for Louisiana-Pacific
Corporation, by Interpoll Laboratories, Inc., Report No. 3-1906, January 1994.
10.6.1-16 EMISSION FACTORS 12/98
-------
51. Results Of The June 28-29, 1994 Air Emission Compliance Tests At The Louisiana-Pacific OSB
Plant In Dungannon Virginia, prepared for Louisiana-Pacific Corporation, by Interpoll
Laboratories, Inc., Report No. 4-3252, August 1994.
52. Data Package For The MD1 Samples Collected At The LP/Dungannon Plant On June 29, 1994
Using The EPA Draft 1,2-PP Method, (data for Reference 51, Report No. 4-3252) prepared for
Louisiana-Pacific Corporation, by Interpoll Laboratories, Inc., August 1994.
53. Louisiana-Pacific Corporation, Oriented Strandboard Facility Fuel Dryer E-Tube Stack,
Montrose, Colorado, June 15, 1995, prepared for Louisiana-Pacific Corporation, by Am Test-Air
Quality, Inc., July 1995.
54. Results Of The March II, 1993 MDI Emission Compliance Tests At The Louisiana-Pacific
Waferboard Plant In Dungannon, Virginia, prepared for Louisiana-Pacific Corporation, by
Interpoll Laboratories, Inc., Report No. 3-8324, April 1993.
55. Results Of The March 29, 1994 Oxides Of Nitrogen Emission Compliance Test On The Dryer
Stack At The Louisiana-Pacific Plant In Dungannon, Virginia , prepared for Louisiana-Pacific
Corporation, by Interpoll Laboratories, Inc., Report No. 4-2557, April 1994.
12/98 Wood Products Industry 10.6.1-17
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10.6.2 Particleboard Manufacturing
Particleboard is defined as a panel product manufactured from lignocellulosic materials, primarily in
the form of discrete particles, combined with a synthetic resin or other suitable binder and bonded together
under heat and pressure. The primary difference between particleboard and other reconstituted wood
products, such as waferboard, oriented strandboard, medium density fiberboard, and hardboard, is the
material or particles used in its production. The major types of particles used to manufacture particleboard
include wood shavings, flakes, wafers, chips, sawdust, strands, slivers, and wood wool. The term
particleboard sometimes is used generically to include waferboard and oriented strandboard, which are
manufactured primarily with wood flakes and wafers. However, for the purposes of this report, particleboard
pertains only to panels manufactured from a mixture of wood particles or otherwise from wood particles other
than wafers and flakes. Particleboard manufacturing falls under Standard Industrial Classification (SIC)
Code 2493, reconstituted wood products, which includes hardboard, insulation board, medium density
fiberboard, waferboard and oriented strandboard in addition to particleboard. The six-digit Source
Classification Code (SCC) for particleboard manufacturing is 3-07-006.
10.6.2.1 Process Description1"6
Particleboard is produced in a wide range of densities. Particleboard with a density of less than
590 kilograms per cubic meter (kg/m3) (37 pounds per cubic foot [lb/ft3]), 590 to 800 kg/m3 (37 to 50 lb/ft3),
and greater than 800 kg/m3 (50 lb/ft3) is classified as low-density, medium density, and high density
particleboard, respectively. However, this report does not distinguish between particleboard densities relative
to emissions from manufacturing operations.
Although some single-layer particleboard is produced, particleboard generally is manufactured in
three or five layers. The outer layers are referred to as the surface or face layers, and the inner layers are
termed the core layers. Face material generally is finer than core material. By altering the relative properties
of the face and core layers, the bending strength and stiffness of the board can be increased.
The general steps used to produce particleboard include raw material procurement or generation,
classifying by size, drying, blending with resin and sometimes wax, forming the resinated material into a mat,
hot pressing, and finishing. Figure 10.6.2-1 presents a process flow diagram for a typical particleboard plant.
The furnish or raw material for particleboard normally consists of wood particles, primarily wood
chips, sawdust, and planer shavings. This material may be shipped to the facility or generated onsite and
stored until needed. In mills where chips are generated onsite, logs are debarked, sawn to proper length, and
chipped. After shipping to the site or generation onsite, the furnish may be further reduced in size by means
of hammermills, flakers, or refiners. After milling, the material is either screened using vibrating or gyratory
screens, or the particles are air-classified. The purpose of this step is to remove the fines and to separate the
core material from the surface material. The screened or classified material then is transported to storage
bins. From the storage bins, the core and surface material are conveyed to dryers. Rotary dryers are the most
commonly used dryer type in the particleboard industry. Both single and triple-pass dryers are used. In
addition, some facilities use tube dryers to dry the furnish. Wood-fired dryers are used at most facilities.
However, gas- and oil-fired dryers also are used. The moisture content of the particles entering the dryers
may be as high as 50 percent on a wet basis. Drying reduces the moisture content to 2 to 8 percent. Dryer
inlet temperatures may be as high as 871 °C (1600°F) if the furnish is wet; for dry furnish, inlet temperatures
generally are no higher than 260°C (500°F). Core dryers generally operate at
9/98 Wood Products Industry 10.6.2-1
-------
Offsite particle generation
Surface
Material
Storage
Drying
Direct/Indirect
Heat
W (2)
A A
Core
Material
Storage
Drying
Resin, wax,
other additives
Blending
(?
_j__'
)
Steam/hot oil
f
Prepressing
*|
Forming
I
i
Trimming
i
Pressing
•__L_
Blend.,,*
i
« Heat, pressure
sr\ /TN
. Resin, wax,
other additives
Cv (£/
A A
Cooling
Sanding
Trimming
Finishing
(V) PM EMISSIONS
0 GASEOUS EMISSIONS
- •*• EMISSION STREAM
—»• PROCESS FLOW
--». OPTIONAL PROCESS
10.6.2-2
Figure 10.6.2-1. Process flow diagram for particleboard manufacturing.
EMISSION FACTORS
9/98
-------
higher temperatures than surface dryers operate due to differences in core and surface particle characteristics
and because a lower moisture content is more desirable for core material.
A two-stage drying arrangement can be used when the moisture content of the incoming furnish is
highly variable. The first stage (predryer) equalizes the moisture content in the furnish; the second stage
(final dryer) is the main dryer. With this arrangement, tube dryers, rotary dryers, or a combination of dryer
types (for example, a tube predryer followed by a rotary final dryer) may be used.
After drying, the particles pass through a primary cyclone for product recovery and then are
transferred to holding bins. Face material sometimes is screened to remove the fines, which tend to absorb
too much of the resin, prior to storage in the holding bins. From the holding bins, the core and surface
materials are transferred to blenders, in which the particles are mixed with resin, wax, and other additives by
means of spray nozzles, tubes, or atomizers. The most commonly used resins are phenol-formaldehyde and
urea-formaldehyde. Generally, urea-formaldehyde resins are used in panels intended for interior applications
and phenol-formaldehyde resins are used to manufacture particleboard for exterior applications.
Waxes are added to impart water resistance, increase the stability of the finished product under wet
conditions, and to reduce the tendency for equipment plugging. For furnishes that are low in acidity, catalysts
also may be blended with the particles to accelerate the resin cure and to reduce the press time. Formaldehyde
scavengers also may be added in the blending step to reduce formaldehyde emissions from the process.
Blenders generally are designed to discharge the resinated particles into a plenum over a belt
conveyor that feeds the blended material to the forming machine, which deposits the resinated material in the
form of a continuous mat. Formers use air to convey the material, which is dropped or thrown into an air
chamber above a moving caul, belt, or screen and floats down into position. To produce multilayer
particleboard, several forming heads can be used in series, or air currents can produce a gradation of particle
sizes from face to core.
As it leaves the former, the mat may be prepressed prior to trimming and pressing. The mats then
are cut into desired lengths and conveyed to the press. The press applies heat and pressure to activate the
resin and bond the fibers into a solid panel. Although some single-opening presses are used, most domestic
particleboard plants are equipped with multi-opening presses, which generally have 14 to 18 openings and
platens that range in size from 1.2 meter (m) by 2.4 m to 2.4 m by 8.5 m (4 ft by 8 ft to 8 ft by 28 ft). Total
press time is generally 2.5 minutes (min) for single-opening presses and 4.2 to 5.8 min for multi-opening
presses. Typical production capacities are 260 to 325 megagrams per day (Mg/d) (286 to 358 ton/d) for
single-opening presses and 520 to 1,180 Mg/d (572 to 1,300 ton/d) for multi-opening presses. Presses
generally are steam-heated using steam generated by a boiler that burns wood residue. However, hot oil and
hot water also are used to heat the press. The operating temperature for particleboard presses generally
ranges from 149° to 182°C (300° to 360°F).
After pressing, the boards generally are cooled prior to stacking. The particleboard panels then are
sanded and trimmed to final dimensions, any other finishing operations (including edge painting and laminate
or veneer application) are done, and the finished product is packaged for shipment.
10.6.2.2 Emissions And Controls J-6-11'14
The primary emission sources at particleboard mills are particle dryers and hot press vents. Other
emission sources may include boilers, particle generation, blending, forming, board cooling, and finishing
operations such as sanding, trimming, edge painting, and laminate or veneer application. Other potential
9/98 Wood Products Industry 10.6.2-3
-------
emissions sources ancillary to the manufacturing process may include wood chip storage piles and bins
(including wood fuel), chip handling systems, and resin storage and handling systems.
Although most particleboard mills have chips delivered from offsite locations, in mills where chips
are generated onsite, operations such as log debarking and sawing, in addition to particle mills, screens, and
classifiers generate paniculate matter (PM) and PM less than 10 micrometers in aerodynamic diameter
(PM-10) emissions in the form of sawdust and wood particles. In addition, these processes may be sources of
PM less than 2.5 micrometers in aerodynamic diameter (PM-2.5) emissions.
Emissions from dryers that are exhausted from the primary recovery cyclone include wood dust and
other solid PM, volatile organic compounds (VOCs), condensible PM, and products of combustion such as
carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NOX), if direct-fired units are used. The
condensible PM and a portion of the VOCs leave the dryer stack as vapor but condense at normal
atmospheric temperatures to form liquid particles or mist that creates a visible blue haze. Both the VOCs and
condensible PM are primarily compounds evaporated from the wood, with a minor constituent being
combustion products. Quantities emitted are dependent on wood species, dryer temperature, fuel used, and
other factors including season of the year, time between logging and processing, and chip storage time.
Emissions from board hot presses are dependent on the type and amount of resin used to bind the
wood fibers together, as well as wood species, wood moisture content, wax and catalyst application rates, and
press conditions. When the press opens, vapors that may include resin ingredients such as formaldehyde,
phenol, and other VOCs are released. The rate at which formaldehyde is emitted during pressing and board
cooling operations is a function of the amount of excess formaldehyde in the resin, board thickness, press
temperature, press cycle time, and catalyst application rates.
Emissions from finishing operations for particleboard are dependent on the type of products being
finished. For most particleboard products, finishing involves trimming to size and, in some cases, painting or
coating the edges. Other products may require sanding or the application of laminate surfaces or veneers with
adhesives. Trimming and sanding operations are sources of PM and PM-10 emissions. In addition, these
processes may be sources of PM less than 2.5 micrometers in aerodynamic diameter (PM-2.5) emissions. No
data specific to particleboard trimming or sawing are available. However, emissions factors for general
sawing operations may provide an order of magnitude estimate for similar particleboard sawing and trimming
operations, bearing in mind that the sawing of dry particleboard panels may result in greater PM, PM-10, and
PM-2.5 emissions than the sawing of green lumber. No data specific to particleboard panel sanding are
available. It is expected that water-based coatings are used to paint particleboard edges, and the resultant
VOC emissions are relatively small. Emissions from adhesives used in the application of laminate surfaces
or veneers are likely to include VOCs.
In particleboard mills where particles are generated onsite, PM, PM-10, and PM-2.5 emissions from
log debarking, sawing, and grinding operations can be controlled through capture in an exhaust system
connected to a sized cyclone and/or fabric filter collection system. Emissions of PM, PM-10, and PM-2.5
from sanding and final trimming operations can be controlled using similar methods. These wood dust
capture and collection systems are used not only to control atmospheric emissions, but also to collect the dust
as a by-product fuel for a boiler or dryer.
Methods of controlling PM emissions from the particle dryer include multiclones, packed bed
absorbers (PBAs), fabric filters, electrified filter beds (EFBs), wet electrostatic precipitators (WESPs), and
incinerators. Emissions are generally controlled with multiclones, EFBs, or WESPs. The EFB uses
electrostatic forces to attract pollutants to an electrically charged gravel bed. The WESP uses electrostatic
forces to attract pollutants to either a charged metal plate or a charged metal tube. The collecting surfaces are
10.6.2-4 EMISSION FACTORS 9/98
-------
continually rinsed with water to wash away the pollutants. Wet PM controls, such as PBA and WESP
systems also may reduce VOC emissions from particle dryers, but to a lesser extent than PM emissions are
reduced by such systems.
A VOC control technology gaining popularity in the wood products industry for controlling both
dryer and press exhaust gases is regenerative thermal oxidation. Thermal oxidizers destroy VOCs, CO, and
condensible organics by burning them at high temperatures. Regenerative thermal oxidizers (RTOs) are
designed to preheat the inlet emission stream with heat recovered from the incineration exhaust gases. Up to
98 percent heat recovery is possible, although 95 percent is typically specified. Gases entering an RTO are
heated by passing through pre-heated beds packed with a ceramic media. A gas burner brings the preheated
emissions up to an incineration temperature between 788° and 871°C (1450° and 1600°F) in a combustion
chamber with sufficient gas residence time to complete the combustion. Combustion gases then pass through
a cooled ceramic bed where heat is extracted. By reversing the flow through the beds, the heat transferred
from the combustion exhaust air preheats the gases to be treated, thereby reducing auxiliary fuel
requirements.
Vendor literature indicates that an RTO can achieve a VOC destruction efficiency of 99 percent. The
literature further indicates that with a particulate prefilter to remove inorganic PM, an RTO system can
achieve a PM control efficiency of 95 percent. Industry experience has shown that RTOs typically achieve 95
percent reduction for VOC (except at inlet concentrations below 20 parts per million by volume as carbon
[ppmvC]), and 70 to 80 percent reduction for CO. However, RTOs typically increase emissions of NOX.
Biofiltration systems can be used effectively for control of a variety of pollutants including organic
compounds (including formaldehyde and benzene), NOX, CO, and PM from both dryer and press exhaust
streams. Data from pilot plant studies in U.S. oriented strandboard mills indicate that biofilters can achieve
VOC control efficiencies of 70 to 90 percent, formaldehyde control efficiencies of 85 to 98 percent, CO
control efficiencies of 30 to 50 percent, NOX control efficiencies of 80 to 95 percent, and resin/fatty acid
control efficiencies of 83 to 99 percent.
Other potential control technologies for particleboard dryers and presses include exhaust gas recycle,
regenerative catalytic oxidation (RCO), absorption systems (scrubbers), and adsorption systems.
Fugitive emissions from road dust and uncovered bark and dust storage piles may be controlled in a
number of different ways. These methods include enclosure, wet suppression systems, and chemical
stabilization. Control techniques for these sources are discussed more fully in AP-42 Chapter 13,
Miscellaneous Sources.
Table 10.6.2-1 summarizes the emission factors for PM emissions from particleboard dryers.
Factors for emissions of SO2, NOX, CO, and CO2 from particleboard dryers are presented in Table 10.6.2-2,
and factors for emissions of organics from particleboard dryers are summarized in Table 10.6.2-3. The
factors for dryer emissions are presented in units of pounds of pollutant per oven-dried ton of wood material
out of the dryer (Ib/ODT). Factors for PM emissions from particleboard presses and board coolers are
presented in Table 10.6.2-4; the factor for press emissions of CO is presented in Table 10.6.2-5; and factors
for press and board cooler emissions of organics are presented in Table 10.6.2-6. The units for the press and
board cooler factors are pounds of pollutant per thousand square feet of 3/4-inch thick panel produced
(lb/MSF-3/4).
Emission factors for mixed hardwood and softwood species are not reported in this section.
Emission factors for specific mixes of wood species may be calculated by combining emission factors for
individual wood species in the ratio specific to a given application, as emission data for those species become
9/98 Wood Products Industry 10.6.2-5
-------
available. For example, a VOC emission factor for a direct wood-fired rotary dryer processing 60 percent
pines and 40 percent hardwoods (and operating at an inlet temperature below 730°F) may be calculated using
the VOC emission factors for unspecified pines (0.95 Ib/ODT for dryers with an inlet air temperature of less
than 730 °F) and hardwoods (0.35 Ib/ODT), and the ratio of 60 percent to 40 percent. The resultant emission
factor, rounded to two significant figures, would be 0.71 Ib/ODT.
10.6.2-6 EMISSION FACTORS 9/98
-------
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-------
Table 10.6.2-3. EMISSION FACTORS FOR PARTICLEBOARD DRYERS--ORGANICSa
Source
Rotary dryer, direct wood fired
Southern yellow pine
(SCC 3-07-006-06)
Rotary dryer, direct wood-fired,
uspecified pines,d <730°F inlet air
(SCC 3-07-006-02)
CASRNb
50-00-0
77-55-6
95-63-6
5779-94-2
108-10-1
101-77-9
80-56-8
10482-56-1
75-07-0
67-64-1
98-86-2
107-02-8
107-13-1
127-91-3
100-52-7
71-43-2
92-52-4
117-81-7
74-83-9
75-15-0
56-23-5
74-87-3
98-82-8
84-74-2
100-41-4
50-00-0
66-25-1
123-31-9
590-86-3
108-38-3,
106-42-3
78-93-3
Pollutant
VOCC
Formaldehyde*
VOCC
1,1,1-Trichloroethane*
1,2,4-Trimethyl benzene
2,5-Dimethyl benzaldehyde
4-Methyl-2-pentanone*
4,4-Methylene dianiline*
Alpha pinene
Alpha terpeneol
Acetaldehyde*
Acetone
Acetophenone*
Acrolein*
Acrylonitrile*
Beta pinene
Benzaldehyde
Benzene*
Biphenyl*
Bis-(2-ethylhexyl phthalate)*
Bromomethane*
Butylbenzyl phthalate
Butylaldehyde
Carbon disulfide*
Carbon tetrachloride*
Chloromethane*
Cumene*
Di-n-butyl phthalate*
Dimethyl sulfide
Ethyl benzene*
Formaldehyde*
Hexaldehyde
Hydroquinone*
Isovaleraldehyde
m,p-Xylene*
m-Tolualdehyde
Methyl ethyl ketone*
Emission
Factor
l.le
0.021
0.95f
1.2E-05
9.0E-05
3.3E-05
8.1E-05
3.3E-05
0.46
0.066
0.010
0.0079
6.4E-05
0.0033
8.9E-05
0.16
0.0026
0.00022
3.9E-05
0.00032
2.8E-05
1.4E-05
0.0031
1.8E-05
1.2E-05
0.0001 1
6.9E-05
2.3E-05
1.4E-05
3.8E-06
0.030
0.016
6.0E-05
0.00052
0.00011
0.00035
0.0013
EMISSION
FACTOR
RATING
D
E
D
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
9/98
Wood Products Industry
10.6.2-9
-------
Table 10.6.2-3. (cont.).
Source
Rotary dryer, direct wood-fired,
unspecified pines,d <730°F inlet air
(SCC 3-07-006-02) (cont.).
Rotary dryer, direct wood-fired,
unspecified pines,d >900°F inlet air
(SCC 3-07-006-04)
CASRNb
75-09-2
110-54-3
98-95-3
95-47-6
99-87-6
100-42-5
108-88-3
110-64-3
108-05-4
5779-94-2
80-56-8
10482-56-1
75-07-0
67-64-1
107-02-8
127-91-3
100-52-7
67-66-3
123-73-9
98-82-8
50-00-0
66-25-1
590-86-3
108-38-3,
106-42-3
78-93-3
75-09-2
529-20-4
95-47-6
99-87-6
104-87-0
123-38-6
Pollutant
Methylene chloride*
n-Hexane*
Nitrobenzene*
o-Xylene*
p-Cymene
Styrene*
Trans l,4dichlorobutene
Toluene*
Valeraldehyde
Vinyl acetate*
VOCC
2,5 Dimethyl benzaldehyde
Alpha pinene
Alpha terpeneol
Acetaldehyde*
Acetone
Acrolein*
Beta pinene
Benzaldehyde
Butyl aldehyde
Chloroform*
Crotonaldehyde
Cumene*
Formaldehyde*
Hexaldehyde
Isovaleraldehyde
m-, p-Xylene*
Methyl ethyl ketone*
Methylene chloride*
n-Butyraldehyde
o-Tolualdehyde
o-Xylene*
p-Cymene
p-Tolualdehyde
Propionaldehyde*
Emission
Factor
0.00066
2.6E-05
1.7E-05
1.4E-05
0.0062
0.00012
2.4E-05
0.0017
0.0045
2.9E-05
8.2f
0.0053
1.9
0.17
0.072
0.16
0.023
0.82
0.12
0.029
0.00010
0.010
0.0020
0.17
0.022
0.018
0.0076
0.0092
0.0022
0.030
0.011
0.00045
0.011
0.026
0.011
EMISSION
FACTOR
RATING
E
E
E
E
E
E
E
E
E
E
D
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
10.6.2-10
EMISSION FACTORS
9/98
-------
Table 10.6.2-3. (cont.).
Source
Rotary dryer, direct wood-fired,
unspecified pines,d >900°F inlet air
(SCC 3-07-006-04) (cont.).
Rotary dryer, direct wood-fired
Hardwoods
(SCC 3-07-006-10)
Rotary dryer, direct natural gas-fired
Unspecified pinesd
(SCC 3-07-006- 11)
CASRNb
100-42-5
108-88-3
110-64-3
Pollutant
Styrene*
Toluene*
Valeraldehyde
VOCC
VOCC
Methane
Emission
Factor
0.00036
0.021
0.014
0.35g
0.9011
0.27
EMISSION
FACTOR
RATING
E
E
E
D
D
E
Factors represent uncontrolled emissions. Emission factor units are pounds of pollutant per oven-dried ton of wood
material out of the dryer (Ib/ODT). One Ib/ODT = 0.5 kg/Mg (oven-dried). Reference 6. SCC = Source
Classification Code. * = hazardous air pollutant.
b CASRN = Chemistry Abstracts Service Registry Number.
c Volatile organic compounds as propane. Based on results of EPA Method 25 A.
d Unspecified pines = mixed pine species or the specific pine species processed were not reported.
e Formaldehyde has been added.
f Formaldehyde has been added; acetone and methylene chloride have been subtracted.
g Formaldehyde has not been added, but is suspected to be present, which would increase the VOC value given.
h Formaldehyde has been added; methane has been subtracted.
9/98
Wood Products Industry
10.6.2-11
-------
Table 10.6.2-4. EMISSION FACTORS FOR PARTICLEBOARD PRESSES
AND BOARD COOLERS--PARTICULATE MATTER3
Source
Batch hot press, UF resin
(SCC 3-07-006-51)
Board cooler, UF resin
(SCC 3-07-006-61)
Filterableb
PM
0.030
0.014
EMISSION
FACTOR
RATING
E
E
PM-10
0.016
0.0034
EMISSION
FACTOR
RATING
D
E
Condensible0
0.061
0.0092
EMISSION
FACTOR
RATING
D
E
a Reference 6 unless noted otherwise. Emission factor units are pounds of pollutant per thousand square feet of
3/4-inch thick panel produced (lb/MSF-3/4). One lb/MSF-3/4 = 0.26 kg/m3. SCC = Source Classification Code.
Factors represent uncontrolled emissions. All data for mills using urea-formaldehyde resins.
b Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent) sampling train.
c Condensible PM is that PM collected in the impinger portion of a PM sampling train.
Table 10.6.2-5. EMISSION FACTORS FOR PARTICLEBOARD PRESSES
AND BOARD COOLERS-CO3
'
Source
Batch hot press, UF resin
(SCC 3-07-006-51)
CO
0.090b
EMISSION
FACTOR
RATING
D
3 Factors represent uncontrolled emissions. SCC = Source Classification Code. Reference 6 unless
otherwise noted. ND = no data available. Emission factor units are pounds of pollutant per thousand
square feet of 3/4-inch thick panel produced (lb/MSF-3/4). One lb/MSF-3/4 = 0.26 kg/m3. All data for
mills using urea-formaldehyde resins.
b References 3,6.
10.6.2-12
EMISSION FACTORS
9/98
-------
Table 10.6.2-6. EMISSION FACTORS FOR PARTICLEBOARD PRESSES
AND BOARD COOLERS-ORGANICS3
Source
Batch hot press, UF resin
(SCC 3-07-006-51)
Veneer hot press, UF resin
(SCC 3-07-020-21)
Board cooler, UF resin
(SCC 3-07-006-61)
CASRNd
5779-94-2
75-07-0
67-64-1
107-02-8
100-52-7
123-73-9
50-00-0
66-25-1
590-86-3
78-93-3
80-56-8
127-91-3
123-38-6
108-88-3
110-64-3
71-55-6
75-07-0
50-00-0
66-25-1
78-93-3
50-00-0
75-07-0
67-64-1
107-02-8
100-52-7
123-73-9
66-25-1
590-86-3
78-93-3
110-62-3
Pollutant
voce
2,5 Dimethyl benzaldehyde
Acetaldehyde*
Acetone
Acrolein*
Benzaldehyde
Butylaldehyde
Crotonaldehyde
Formaldehyde*
Hexaldehyde
Isovaleraldehyde
Methyl ethyl ketone*
a-Pinene
b-Pinene
Propionaldehyde*
Toluene*
Valeraldehyde
1,1,1-Trichloroethane*
Acetaldehyde*
Butylaldehyde
Formaldehyde*
Hexaldehyde
Methyl ethyl ketone*
voce
Formaldehyde*
Acetaldehyde*
Acetone
Acrolein*
Benzaldehyde
Butylaldehyde
Crotonaldehyde
Hexaldehyde
Isovaleraldehyde
Methyl ethyl ketone*
Valeraldehyde
Emission
Factor
094b,f
0.00032
0.014b
0.013
0.0019
0.0018b
0.0018b
0.00050
0.26b
0.045b
0.0011
0.0014b
0.00054°
0.00011°
7.2E-05
0.00047°
0.0039
0.00022°
9.9E-05C
0.00014°
0.0062°
0.11°
0.00028°
0.27f
0.027
0.001 3b
0.0020
0.00036
0.00042b
0.00060b
0.00029
0.001 lb
0.00040
0.00011
0.0015
EMISSION
FACTOR
RATING
D
E
E
E
E
E
E
E
D
E
E
E
E
E
E
E
E
E
E
E
E
E
E
D
D
E
E
E
E
E
E
E
E
E
E
a Emission factor units are pounds of pollutant per thousand square feet of 3/4-inch thick panel produced (lb/MSF-3/4).
One lb/MSF-3/4 = 0.26 kg/nr. Factors represent uncontrolled emissions. Reference 6 unless otherwise noted. SCC
= Source Classification Code. All data for mills using urea-formaldehyde resins. * = hazardous air pollutant.
References 3,6.
c References.
d CASRN = Chemistry Abstracts Service Registry Number.
" Volatile organic compounds on a propane basis. Factors are based on Method 25A.
Formaldehyde has been added; acetone has been subtracted.
9/98
Wood Products Industry
10.6.2-13
-------
References For Section 10.6.2
1. T. M. Maloney, Modern Particleboard And Dry-Process Fiberboard Manufacturing, Miller
Freeman Publications, Inc., San Francisco, CA, 1977.
2. J. G. Haygreen and J. L. Bowyer, Forest Products And Wood Science: An Introduction, Second
Edition, Iowa State University Press, Ames, LA, 1989.
3. Emission Test Report: HAP Emission Testing On Selected Sources At A Wood Furniture
Production Facility—Facility A, prepared for U. S. Environmental Protection Agency, Research
Triangle Park, NC, by Roy F. Weston, Inc., April 1993.
4. Emission Test Report: HAP Emission Testing At Facility B, EMB Report 92-PAR-02 prepared for
. U. S. Environmental Protection Agency, Research Triangle Park, NC, May 1993.
5. Particleboard Production Facility Emission Test Report: Georgia-Pacific Corporation, Vienna,
Georgia, EMB Report 93-PAR-03 prepared for U. S. Environmental Protection Agency, Research
Triangle Park, NC, April 1993.
6. Particleboard And Medium Density Fiberboard A ir Emission Databases, Technical Bulletin No.
693, the National Council of the Paper Industry for Air and Stream Improvement, New York, NY,
April 1995.
7. Stationary Source Sampling Report, Reference No. 6393A, Weyerhaeuser Company, Moncure,
North Carolina, Formaldehyde Emissions, Particulate Emissions, And Plume Opacity Testing,
Core Line EFB Inlet, Core Line Stack, and Surface Line Stack, August 9 And 11, 1989 , Entropy
Environmentalists, Inc., Research Triangle Park, NC, September 21, 1989.
8. Stationary Source Sampling Report, Reference No. 6041 A, Weyerhaeuser Company, Moncure,
North Carolina, Particulate Emissions And Plume Opacity Testing, Surface Line Electrified Filter
Bed Inlet And Stack, October 20, 1988, Entropy Environmentalists, Inc., Research Triangle Park,
NC, November 8, 1988.
9. Weyerhaeuser Company, Marshfield, Wisconsin, Stack Testing Report For Total Gaseous Non-
Methane Organic Compound Emissions (TGNOC), Test Date: March 19-23, 1990 ,
Cross/Tessitore & Associates, P.A., Orlando, FL, 1990.
10. Report To Weyerhaeuser Company, Marshfield, Wisconsin, For Particulate & NO x Emissions
Testing, Door Core Dryer EFB Stack, December 20, 1991, Environmental Technology &
Engineering Corporation, Elm Grove, WI, 1992.
11. Written communication and attachments from T. A. Crabtree, Smith Engineering Company,
Broomall, PA, to P. E. Lassiter, U. S. Environmental Protection Agency, Research Triangle Park,
NC, July 26,1996.
12. Technical Memorandum, Minutes of the October 12-13,1993 BACT Technologies Workshop,
Raleigh, NC, sponsored by the American Forest and Paper Association, K. D. Bullock, Midwest
Research Institute, Gary, NC, October 1993.
10.6.2-14 EMISSION FACTORS 9/98
-------
13. A. E. Cavadeas, RTO Experience In The Wood Products Industry, presented at Environmental
Challenges: What's New in the Wood Products Industry?, workshop sponsored by the American
Forest and Paper Association, Research Triangle Park, NC, February 4-5, 1997.
14. Emission Factor Documentation for AP-42, Section 10.6.2, prepared for the U. S. Environmental
Protection Agency, OAQPS/EFIG, by Midwest Research Institute, Gary, NC, September 1998.
9/98 Wood Products Industry 10.6.2-15
-------
10.6.3 Medium Density Fiberboard Manufacturing
10.6.3.1 General1'2-8
The Composite Panel Association defines medium density fiberboard (MDF) as a dry-formed panel
product manufactured from lignocellulosic fibers combined with a synthetic resin or other suitable binder.
The panels are compressed to a density of from 496 to 801 kilograms per cubic meter (kg/m3) (31 to 50
pounds per cubic foot [lb/ft3]) in a hot press. The entire interfiber bond is formed by a synthetic resin or
other suitable organic binder.
In contrast to particleboard, MDF has more uniform density throughout the board and has smooth,
tight edges that can be machined. It can be finished to a smooth surface and grain printed, eliminating the
need for veneers and laminates. Most of the thicker MDF panels (1.27 to 1.91 centimeters [cm]) (1/2 to
3/4 inch [in.]) are used as core material in furniture panels. Medium density fiberboard panels thinner than
1.27 cm (1/2 in.) typically are used for siding.
10.6.3.2 Process Description2-8
The general steps used to produce MDF include mechanical pulping of wood chips to fibers
(refining), drying, blending fibers with resin and sometimes wax, forming the resinated material into a mat,
and hot pressing. Figure 10.6.3-1 presents a process flow diagram for a typical MDF plant.
The furnish for MDF normally consists of wood chips. Wood chips typically are delivered by truck
or rail from offsite locations such as sawmills, plywood plants, furniture manufacturing facilities, satellite
chip mills, and whole tree chipping operations. If wood chips are prepared onsite, logs are debarked, cut to
more manageable lengths, and then sent to chippers. If necessary, the chips are washed to remove dirt and
other debris.
Clean chips are softened by steam and then sent to atmospheric or pressurized disk refiners, also
known as attrition mills. The refiners use single or double revolving disks to mechanically pulp the chips to
obtain fibers in a suitable form for making the board.
From the refiners, the fibers move to the drying and blending area. Tube dryers are typically used to
reduce the moisture content of the fibers to desired levels. Heat is usually provided by the direct firing of
propane, natural gas, or distillate oil. Two-stage dryers are used when the moisture content of the incoming
furnish is highly variable. The first stage equalizes the moisture content in the furnish; the second stage is the
main dryer.
The sequence of the drying and blending operations depends on the method by which resins and other
additives are blended with the fibers. Some plants inject resins into a short-retention blender, while others
inject resin formulations into a blowline system. If resin is added in a separate blender, the fibers are first
dried and separated from the gas stream by a primary cyclone, then conveyed to the blender. The fibers then
are blended with resin, wax, and any other additives and conveyed to a dry fiber storage bin. Urea-
formaldehyde (UF) resins are the most common resins used in the manufacture of MDF. Phenolic resins and
melamine resins are also used.
9/98 Wood Products Industry 10.6.3-1
-------
© © ©
i i i
1 1 1
WOOD CHIPS
CHIP
STORAGE
CHIP
WASHING
(OPTIONAL)
STEAMING
DRYER CYCLONE EMISSIONS
i A
POTENTIAL
i i
FIBER
TUBE
DRYER
RESIN, WAX, ADDITIVES
I
RESIN, WAX,
ADDITIVES
DRYING AND BLENDING AREA
WASTE RECYCLE
PACKAGING/
SHIPPING
0 PM EMISSIONS
/5\ GASEOUS EMISSIONS
©
i
PAINTING/
LAMINATING
(OPTIONAL)
©
A
i
TRIMMING,
SANDING,
SAWING
1
WASTE RECYCLE
©
i
BOARD
COOLING
Figure 10.6.3-1. Typical process flow diagram for a medium density fiberboard (MDF) plant.
10.6.3-2 EMISSION FACTORS 9/98
-------
If a blowline system is used, the fibers are first blended with resin, wax, and other additives in a
blowpipe that discharges the resinated fibers to the dryer. After drying, the fibers are separated from the gas
stream by a primary cyclone and then conveyed to a dry fiber storage bin.
Air conveys the resinated fibers from the dry storage bin to the forming machine, where they are
deposited on a continuously moving screen system. The continuously formed mat must be prepressed before
being loaded into the hot press. After prepressing, some pretrimming is done. The trimmed material is
collected and recycled to the forming machine.
The prepressed and trimmed mats then are transferred to the hot press. The press applies heat and
pressure to activate the resin and bond the fibers into a solid panel. The mat may be pressed in a continuous
hot press, or the precompressed mat may be cut by a flying cutoff saw into individual mats that are then
loaded into a batch-type hot press. Radio-frequency (RF) heating and steam heating of the press platens are
common in domestic MDF plants. After pressing, the boards are cooled, sanded, trimmed to final
dimensions, any other finishing operations are done, and the finished product is packaged for shipment.
10.6.3.3 Emissions And Controls2"8
The primary emission sources at MDF mills are fiber dryers and press vents. Other emission sources
may include boilers, chip production operations, and finishing operations such as sanding, trimming, edge
painting, and laminate application.
Although most MDF mills have chips delivered from offsite locations, in mills where chips are
generated onsite, operations such as log debarking, sawing, chipping, and grinding generate paniculate matter
(PM) and PM less than 10 micrometers (PM-10) emissions in the form of sawdust and wood particles.
Emissions from dryers that are exhausted from the primary recovery cyclone include wood dust and
other solid PM, volatile organic compounds (VOCs), condensible PM, and products of combustion such as
carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NOX), if direct-fired units are used. The
condensible PM and a portion of the VOCs leave the dryer stack as vapor but condense at normal
atmospheric temperatures to form liquid particles or mist that creates a visible blue haze. Both the VOCs and
condensible PM are primarily compounds evaporated from the wood, with a minor constituent being
combustion products. Quantities emitted are dependent on wood species, dryer temperature, fuel used, and
other factors including season of the year, time between logging and processing, and chip storage time.
Calculating PM-10 emissions from the wood products industries is problematic due to the
relationship between PM-10 (or PM) emissions and VOC emissions from these processes. Because the
Method 201A train (PM-10) operates with an in-stack cyclone and filter, organic materials that are volatile at
stack gas temperatures but that are condensed at back half impinger temperatures (~20°C [~68°F]) are
collected as condensible PM-10. However, these materials will also be measured as VOCs via Methods 25
and 25A, which operate with a heated or an in-stack filter. Hence, if PM-10 is calculated as the sum of
filterable and condensible material, some pollutants will be measured as both PM-10 and VOC emissions.
However, if only filterable material is considered to be PM-10, the PM-10 emission factors will be highly
dependent on stack gas temperature. In this AP-42 section, PM-10 is reported as front half catch only
(Method 201A results only; condensible PM, based on Method 202 results are not included). However,
separate emission factors for condensible PM are presented, and those emission factors can be combined with
the PM-10 emission factors as appropriate for a specific application. Measured VOC emissions may be
affected by the sampling method and by the quantity of formaldehyde and other aldehydes and ketones in the
exhaust; formaldehyde is not quantified using Method 25A, and other low molecular weight oxygenated
compounds have reduced responses to Method 25A. Therefore, when VOC emissions are measured using
9/98 Wood Products Industry 10.6.3-3
-------
Method 25A, the emission rates will be biased low if low molecular weight oxygenated compounds are
present in significant concentrations in the exhaust stream. A more extensive discussion of these sampling
and analysis issues is provided in the background report for this section (Reference 8).
Emissions from board hot presses are dependent on the type and amount of resin used to bind the
wood fibers together, as well as wood species, wood moisture content, wax and catalyst application rates, and
press conditions. When the press opens, vapors that may include resin ingredients such as formaldehyde,
phenol, and other VOCs are released. The rate at which formaldehyde is emitted during pressing and board
cooling operations is a function of the amount of excess formaldehyde in the resin, board thickness, press
temperature, press cycle time, and catalyst application rates.
Only limited data are available on emissions of the organic constituents included in the exhaust
streams from MDF dryers and presses. However, speciated organic emission data for waferboard/oriented
strandboard (WB/OSB) and particleboard may provide an indication of the types of organic compounds
emitted from MDF dryers and presses. Emission factors for speciated organic emissions from WB/OSB and
particleboard dryers and presses are included in AP-42 Sections 10.6.1 and 10.6.2, respectively.
Emissions from finishing operations for MDF are dependent on the type of products being finished.
For most MDF products, finishing involves trimming to size and, in some cases, painting or coating the
edges. Other products may require sanding or the application of laminate surfaces with spray adhesives.
Trimming and sanding operations are sources of PM and PM-10 emissions. No data specific to MDF
trimming or sawing are available. However, emission factors for general sawing operations may provide an
order of magnitude estimate for similar MDF sawing and trimming operations, bearing in mind that the
sawing of dry MDF panels may result in greater PM and PM-10 emissions than the sawing of green lumber.
No data specific to MDF panel sanding are available. It is expected that water-based coatings are used to
paint MDF edges, and the resultant VOC emissions are relatively small. Emissions from adhesives used in
the application of laminate surfaces are likely to include VOCs.
In MDF mills where wood chips are generated onsite, PM and PM-10 emissions from log debarking,
sawing, and grinding operations can be controlled through capture in an exhaust system connected to a sized
cyclone and/or fabric filter collection system. These wood dust capture and collection systems are used not
only to control atmospheric emissions, but also to collect the dust as a by-product fuel for a boiler or dryer.
A VOC control technology gaining popularity in the wood products industry for controlling both
dryer and press exhaust gases is regenerative thermal oxidation. Thermal oxidizers destroy VOCs, CO, and
condensible organics by burning them at high temperatures. Regenerative thermal oxidizers (RTOs) are
designed to preheat the inlet emission stream with heat recovered from the incineration exhaust gases. Up to
98 percent heat recovery is possible, although 95 percent is typically specified. Gases entering an RTO are
heated by passing through pre-heated beds packed with a ceramic media. A gas burner brings the preheated
emissions up to an incineration temperature between 788° and 871 °C (1450° and 1600°F) in a combustion
chamber with sufficient gas residence time to complete the combustion. Combustion gases then pass through
a cooled ceramic bed where heat is extracted. By reversing the flow through the beds, the heat transferred
from the combustion exhaust air preheats the gases to be treated, thereby reducing auxiliary fuel
requirements.
Biofiltration systems can be used effectively for control of a variety of pollutants including organic
compounds (including formaldehyde and benzene), NOX, CO, and PM from both dryer and press exhaust
streams. Data from pilot plant studies in U.S. OSB mills indicate that biofilters can achieve VOC control
efficiencies of 70 to 90 percent, formaldehyde control efficiencies of 85 to 98 percent, CO control efficiencies
10.6.3-4 EMISSION FACTORS 9/98
-------
of 30 to 50 percent, NOX control efficiencies of 80 to 95 percent, and resin/fatty acid control efficiencies of
83 to 99 percent.
Other potential control technologies for MDF dryers and presses include regenerative catalytic
oxidation (RCO), absorption systems (scrubbers), and adsorption systems.
Fugitive emissions from road dust and uncovered bark and dust storage piles may be controlled in a
number of different ways. These methods include enclosure, wet suppression systems, and chemical
stabilization. Control techniques for these sources are discussed more fully in AP-42 Chapter 13,
Miscellaneous Sources.
Table 10.6.3-1 presents emission factors for dryer emissions of PM, including filterable PM,
filterable PM-10, and condensible PM. Table 10.6.3-2 presents emission factors for dryer emissions of SO2,
NOX, CO, and CO2. Table 10.6.3-3 presents emission factors for dryer emissions of organic pollutants.
Table 10.6.3-4 presents emission factors for press and board cooler emissions of PM, including filterable
PM, filterable PM-10, and condensible PM. Table 10.6.3-5 presents emission factors for press emissions of
NOX and CO. Table 10.6.3-6 presents emission factors for press and board cooler emissions of organic
pollutants.
Emission factors for specific mixes of wood species may be calculated by combining emission
factors for individual wood species in the ratio specific to a given application, as emission data for those
species become available. For example, a VOC emission factor for a direct wood-fired tube dryer processing
60 percent pine and 40 percent hardwood may be calculated using the VOC emission factors for unspecified
pines (6.6 Ib/ODT) and hardwood (6.5 Ib/ODT). In this specific example, the pine emission factor is based
on only Method 25A data. The hardwood factor is based on Method 25A plus formaldehyde. In order to
compare like values, formaldehyde should be subtracted out of the hardwood factor to yield the emission
factor for hardwood based on Method 25A only (5.6 Ib/ODT). Using the two factors based on Method 25A
(6.6 Ib/ODT and 5.6 Ib/ODT) and the ratio of 60 percent to 40 percent, the resultant emission factor, rounded
to two significant figures, would be 6.2 Ib/ODT. Corrections for formaldehyde and for non-VOC compounds
can be made as emission data for these compounds become available.
9/98 Wood Products Industry 10.6.3-5
-------
Table 10.6.3-1. EMISSION FACTORS FOR MDF DRYERS--PARTICULATE MATTERa
Source
Tube dryer, direct wood-fired
Unspecified pines6
(SCC 3-07-009-21)
Tube dryer, indirect heat
Unspecified pines6
(SCC 3-07-009-31)
Mixed speciesf
(SCC 3-07-009-39)
Emission
Controlb
None
None
None
Filterable0
PM
10
1.4
1.5
EMISSION
FACTOR
RATING
D
E
E
PM-10
1.6
ND
0.28
EMISSION
FACTOR
RATING
D
E
Condensibled
0.59
ND
0.73
EMISSION
FACTOR
RATING
D
E
a Emission factor units are pounds per oven-dried ton (Ib/ODT) of wood material out of dryer. One Ib/ODT
= 0.5 kg/Mg (oven-dried). SCC = Source Classification Code. Reference 5. ND = no data available.
b Cyclones are used as product recovery devices and are not considered to be emission control equipment.
c Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent) sampling
train.
d Condensible PM is that PM collected in the impinger portion of a PM sampling train.
e Unspecified pines = mixed pine species or the specific pine species processed were not reported.
Mixed species = 50 percent hardwood and 50 percent softwood.
10.6.3-6
EMISSION FACTORS
9/98
-------
Table 10.6.3-2. EMISSION FACTORS FOR MDF DRYERS--SO2, NOX, CO, AND CO2a
Source
Tube dryer, direct wood-fired
(SCC 3-07-009-21, 3-07-009-25)
SO2
ND
EMISSION
FACTOR
RATING
NOX
ND
EMISSION
FACTOR
RATING
CO
4.0
EMISSION
FACTOR
RATING
D
C02
ND
EMISSION
FACTOR
RATING
a Factors represent uncontrolled emissions. SCC = Source Classification Code. ND = no data available.
NR = not reported. All emission factors in units of pounds per oven-dried ton (Ib/ODT) of wood material
out of dryer. One Ib/ODT = 0.5 kg/Mg (oven-dried). Reference 5.
9/98
Wood Products Industry
10.6.3-7
-------
Table 10.6.3-3. EMISSION FACTORS FOR MDF DRYERS--ORGANICSa
Source
Tube dryer, direct wood-fired
Unspecified pinesb
(SCC 3-07-009-21)
Hardwoods
(SCC 3-07-009-25)
Tube dryer, indirect heat
Hardwoods
(SCC 3-07-009-35)
Mixed speciesf
(SCC 3-07-009-39)
-
CASRNh
50-00-0
50-00-0
75-07-0
50-00-0
5779-94-2
75-07-0
67-64-1
98-86-2
107-02-8
80-56-8
10482-56-1
100-52-7
117-81-7
127-91-3
74-87-3
123-73-9
84-74-2
66-25-1
540-84-1
590-86-3
78-93-3
75-09-2
91-20-3
Pollutant
VOCC
VOCC
Formaldehyde*
VOCC
Formaldehyde*
Acetaldehyde*
VOCC
Formaldehyde*
2,5-Dimethyl benzaldehyde
Acetaldehyde*
Acetone
Acetophenone*
Acrolein*
Alpha pinene
Alpha terpeneol
Benzaldehyde
Bis-(2-ethylhexyl phthalate)*
Butylbenzyl phthalate
Butylaldehyde
Beta pinene
Chloromethane*
Crotonaldehyde
Di-n-butyl phthalate*
Hexaldehyde
Isooctane*
Isovaleraldehyde
Methyl ethyl ketone*
Methylene chloride*
Naphthalene*
Emission
Factor
6.6d
6.5e
0.86
4.7e
0.20
0.013
2.2^
1.4
3.8 x 1Q-4
0.013
0.0025
2.4 x 1Q-4
0.0022
0.0062
0.0022
0.0026
2.7 x 10"4
2.4 x 1Q-4
0.0028
0.0064
0.0015
0.0019
1.8 xlO"4
0.0026
6.2 x 1Q-4
0.0019
0.0063
0.0029
6.6 x 10-4
EMISSION
FACTOR
RATING
E
D
E
D
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
10.6.3-8
EMISSION FACTORS
9/98
-------
Table 10.6.3-3. (cont.).
Source
Mixed speciesf
(cont.)
CASRNh
110-54-3
529-20-4
108-95-2
123-38-6
99-87-6
104-87-0
75-69-4
110-62-3
Pollutant
n-Hexane*
o-Tolualdehyde
Phenol*
Propionaldehyde*
p-Cymene
p-Tolualdehyde
Trichlorofluoromethane
Valeraldehyde
Emission
Factor
0.0014
7.4 x 10"4
2.0 x ID"4
0.0011
1.9X10-4
0.0036
0.0014
0.0021
EMISSION
FACTOR
RATING
E
E
E
E
E
E
E
E
a Factors represent uncontrolled emissions. SCC = Source Classification Code. All emission factors in units
of pounds per oven-dried ton of wood material out of dryer (Ib/ODT). One Ib/ODT = 0.5 kg/Mg (oven-
dried). References. * = hazardous air pollutant.
b Unspecified pines = mixed pine species or the specific pine species processed were not reported.
c Volatile organic compounds as propane. Based on results of EPA Method 25A.
Formaldehyde has not been added, but is suspected to be present, which would increase the VOC value
given.
e Formaldehyde has been added.
f Mixed species = 50 percent hardwood and 50 percent softwood.
g Formaldehyde has been added; acetone and methylene chloride have been subtracted.
h CASRN = Chemistry Abstracts Service Registry Number.
9/98
Wood Products Industry
10.6.3-9
-------
Table 10.6.3-4. EMISSION FACTORS FOR MDF PRESSES AND BOARD COOLERS-
PARTICULATE MATTER3
Source
Batch hot press , UF resin
(SCC 3-07-009-60)
Continuous hot press, UF
resin
(SCC 3-07-009-50)
Uncontrolled6
RTO-controllede
MDF board cooler, UF
resin
(SCC 3-07-009-71)
Filterableb
PMC
0.18
0.17
0.040
0.054
EMISSION
FACTOR
RATING
D
E
E
E
PM-10
0.075
ND
ND
0.0038
EMISSION
FACTOR
RATING
E
E
Condensibled
0.26
0.14
0.016
ND
EMISSION
FACTOR
RATING
E
E
E
a Reference 5 unless otherwise noted. Emission factor units are Ib/thousand square feet of 3/4-inch thick
panel (lb/MSF-3/4). One lb/MSF-3/4 = 0.26 kg/m3. SCC = Source Classification Code. ND = no data
available. Factors represent uncontrolled emissions unless otherwise noted.
b Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent) sampling
train.
c Filterable PM emissions from process consist primarily of filterable PM-10.
d Condensible PM is that PM collected in the impinger portion of a PM sampling train.
e Reference 9.
10.6.3-10
EMISSION FACTORS
9/98
-------
Table 10.6.3-5. EMISSION FACTORS FOR MDF PRESSES--NOX AND COa
Source
Batch hot press, UF resin
(SCC 3-07-009-60)
Continuous hot press, UF resin
(SCC 3-07-009-50)
Uncontrolledb
RTO-controlledb
NOX
0.030
ND
0.51
EMISSION
FACTOR
RATING
E
E
CO
0.034
ND
0.085
EMISSION
FACTOR
RATING
E
E
a Factors represent uncontrolled emissions unless otherwise noted. SCC = Source Classification Code.
Reference 5 unless otherwise noted. ND = no data available. Emission factor units are pounds per
thousand square feet of 3/4-inch thick panel (lb/MSF-3/4). One lb/MSF-3/4 = 0.26 kg/m3. All data for
mills using urea-formaldehyde resins.
b Reference 9.
Wood Products Industry
10.6.3-11
-------
Table 10.6.3-6. EMISSION FACTORS FOR MDF PRESSES AND BOARD COOLERS-
ORGANICS3
Source
Batch hot press, UF resin
(SCC 3-07-009-60)
Continuous hot press, UF resin
(SCC 3-07-009-50)
Uncontrolledd
RTO-controlledd
MDF board cooler, UF resin
(SCC 3-07-009-71)
CASRN6
5779-94-2
75-07-0
67-64-1
107-02-8
100-52-7
123-73-9
50-00-0
66-25-1
590-86-3
78-93-3
529-20-4
123-38-6
104-87-0
110-62-3
50-00-0
50-00-0
5779-94-2
75-07-0
67-64-1
107-02-8
100-52-7
123-73-9
50-00-0
66-25-1
590-86-3
78-93-3
Pollutant
vocb
2,5-Dimethyl benzaldehyde
Acetaldehyde*
Acetone
Acrolein*
Benzaldehyde
Butylaldehyde
Crotonaldehyde
Formaldehyde*
Hexaldehyde
Isovaleraldehyde
Methyl ethyl ketone*
o-Tolualdehyde
Propionaldehyde*
p-Tolualdehyde
Valeraldehyde
vocb
Formaldehyde*
vocb
Formaldehyde*
vocb
2,5-Dimethyl benzaldehyde
Acetaldehyde*
Acetone
Acrolein*
Benzaldehyde
Butylaldehyde
Crotonaldehyde
Formaldehyde*
Hexaldehyde
Isovaleraldehyde
Methyl ethyl ketone*
Emission
Factor
0.69C
0.0025
0.0051
0.0031
0.0012
0.00055
0.0024
0.0011
0.30
0.0029
0.0014
0.00059
0.00070
0.00054
0.0010
0.0024
1.4C
1.1
0.032C
0.0091
0.20C
0.00019
0.0010
0.0021
0.00022
9.9 xlO'5
0.0014
0.00026
0.11
0.00065
0.00025
0.0001 1
EMISSION
FACTOR
RATING
D
E
E
E
E
E
E
E
D
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
10.6.3-12
EMISSION FACTORS
9/98
-------
Table 10.6.3-6. (cont.).
Source
Board cooler, UF resin
(cont.).
CASRN6
529-20-4
104-87-0
110-62-3
Pollutant
o-Tolualdehyde
p-Tolualdehyde
Valeraldehyde
Emission
Factor
6.5 x 10'5
0.00017
0.00048
EMISSION
FACTOR
RATING
E
E
E
a Emission factor units are pounds per thousand square feet of 3/4-inch thick panel (lb/MSF-3/4). One
lb/MSF-3/4 = 0.26 kg/m3. Factors represent uncontrolled emissions unless otherwise noted. Reference 5
unless otherwise noted. SCC = Source Classification Code. All data for mills using urea-formaldehyde
resins. * = hazardous air pollutant.
b Volatile organic compounds on a propane basis. Factors are based on Method 25A results. For total
VOC, add the appropriate formaldehyde emission factors (where available).
c Formaldehyde has been added.
d Reference 9.
e CASRN = Chemistry Abstracts Service Registry Number.
9/98
Wood Products Industry
10.6.3-13
-------
References For Section 10.6.3
1. T. M. Maloney, Modern Particleboard And Dry-Process Fiberboard Manufacturing, Miller
Freeman Publications, Inc., San Francisco, CA, 1977.
2. J. G. Haygreen and J. L. Bowyer, Forest Products And Wood Science: An Introduction, Second
Edition, Iowa State University Press, Ames, LA, 1989.
3. O. Suchsland and G. E. Woodson, Fiberboard Manufacturing Practices In The United States,
Agriculture Handbook No. 640, U. S. Department of Agriculture, Forest Service, 1986.
4. C. C. Vaught, Evaluation Of Emission Control Devices At Wqferboard Plants , EPA-450/3-90-002,
Control Technology Center, Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC, October 1990.
5. Particleboard And Medium Density Fiberboard Air Emission Databases, Technical Bulletin
No. 693, the National Council of the Paper Industry for Air and Stream Improvement, New York,
NY, April 1995.
6. Written communication and attachments from T. A. Crabtree, Smith Engineering Company,
Broomall, PA, to P. E. Lassiter, U. S. Environmental Protection Agency, Research Triangle Park,
NC, July 26, 1996.
7. Technical Memorandum, Minutes of the October 12-13, 1993 BACT Technologies Workshop,
Raleigh, NC, sponsored by the American Forest and Paper Association, K. D. Bullock, Midwest
Research Institute, Gary, NC, October 1993.
8. Emission Factor Documentation For AP-42 Section 10.6.3, prepared for the U. S. Environmental
Protection Agency, OAQPS/EFIG, by Midwest Research Institute, Gary, NC, August 1998.
9. Report Of Air Emissions And Inlet Loading Tests For Louisiana-Pacific Corporation Urania MDF
Plant, Urania, Louisiana, January 18 through 21, 1994, prepared by Environmental Monitoring
Laboratories, Ridgeland, MS, February 1994.
10.6.3-14 EMISSION FACTORS 9/98
-------
10.8 Wood Preserving1'3
Wood preservation is the pressure or thermal impregnation of chemicals into wood to provide
effective long-term resistance to attack by fungi, bacteria, insects, and marine borers. By extending the
service life of timber products, wood preservation reduces the need for harvest of already stressed forestry
resources, reduces operating costs in industries such as utilities and railroads, and ensures safe working
conditions where timbers are used as support structures.
Seventy-five percent of the wood treatment plants in the United States are concentrated in two
distinct regions. One of these regions extends from east Texas to Maryland, corresponding roughly to the
natural range of southern pines, which is the major species utilized. The second, smaller region is along the
Pacific coast, where Douglas fir and western red cedar are the predominant species. The remaining
25 percent of wood treatment plants are scattered throughout the United States.
10.8.1 Process Description2"9
10.8.1.1 Preservatives -
There are two general classes of wood preservatives: oils, such as creosote and petroleum solutions
of pentachlorophenol; and waterborne salts that are applied as water solutions. The effectiveness of the
preservatives varies greatly and can depend not only upon its composition, but also upon the quantity injected
into the wood, the depth of penetration, and the conditions to which the treated material is exposed in service.
10.8.1.2 Conditioning-
With most wood treating methods, significant amounts of free water in the wood cell cavities may
slow or prevent the entrance of the preservative chemical. Therefore, wood moisture content must be reduced
prior to treatment. Moisture reduction can be accomplished by using artificial conditioning treatments or by
air-seasoning (i.e., storing the untreated wood outdoors in piles). Unseasoned wood that is exposed to the
open air generally dries slowly until it comes into approximate equilibrium with the relative humidity of the
air. However, some wood species will rot before the air drying is complete.
Because certain wood species will rot before air drying can be completed in some climates, wood is
artificially conditioned by one of three primary methods: (1) steaming-and-vacuum, (2) boiling-under-
vacuum (commonly referred to as the Boulton process), and (3) kiln drying. Vapor drying also has been used
but currently is used rarely, if ever. These conditioning treatments remove a substantial amount of moisture
from the wood and also heat the wood to a more favorable treating temperature. Steaming and Boultonizing -
have the added effect of disinfecting the wood. In segregated systems, conditioning is performed in separate
"clean" cylinders that do not contain preservative.
The steaming and vacuum method of conditioning is used primarily for treating southern pine poles.
Steaming and vacuum may be performed in a dedicated cylinder or in the same cylinder used for treating the
wood. In this process, the wood charge is heated with live steam. Then, a vacuum is drawn.
The Boulton process is used primarily for Douglas fir and hardwoods. The Boulton process usually
is performed in the same cylinder used to treat the wood. In this process, the cylinder is charged with wood,
and heated preservative is used to heat the wood charge for 1 to 24 hours. At that point, a vacuum is drawn.
Finally, the preservative is returned to the work tank. This step is referred to as "blow back" from the
practice of using compressed air to blow the preservative back into the work tank. However, many treatment
8/99 Wood Products Industry 10.8-1
-------
systems use pumps to withdraw preservative from the treatment cylinder and return it to the work tank.
Although such systems do not actually blow back the preservative, the term still is used to refer to this step of
the process.
10.8.1.3 Treating-
Most wood-preserving methods may be classified as either pressure processes, in which the wood is
placed in a treating cylinder or retort and impregnated with preservative under considerable force, and
nonpressure processes, which do not involve the use of induced pressure. Nonpressure processes can be
classified as thermal processes, in which heat is applied, and nonthermal processes, such as brushing,
spraying, dipping, and soaking. Nonpressure processes generally are used only with oilbome preservatives.
Because the majority of wood treated annually is impregnated by pressure methods in closed cylinders, only
pressure processes are discussed in the following sections.
. Pressure processes operate on the same general principle, though they may differ in the specifics of
the process. The treatment is carried out in steel cylinders or retorts. Most units conform to size limits of 2
to 3 meters (m) (6 to 9 feet [ft]) in diameter and up to 46 m (150 ft) or more in length, and are built to
withstand working pressures up to 1,720 kilopascals (kPa) (250 pounds per square inch [psi]). The wood is
loaded on special tram cars and moved into the retort, which is then closed and filled with preservative.
Applied pressure forces preservatives into the wood until the desired amount has been absorbed. Three
processes, the full-cell, modified full-cell, and empty-cell, are in common use. These processes are
distinguished by the sequence in which vacuum and pressure are applied to the retort. The terms "empty" and
"full" refer to the level of preservative retained in the wood cells. The full-cell process achieves a high level
of retention of preservative in the wood cells, but less penetration than the empty-cell process, and the empty-
cell process achieves relatively deep penetration with less preservative retention than does the full- cell
process.
Full-Cell Process -
The full-cell (Bethel) process is used when maximum preservative retention levels are desired, such
as when treating timbers with creosote for protection against marine borers. Figure 10.8-1 presents a flow
diagram for the full-cell pressure treating process. In addition to creosote, the full-cell process also is used
primarily with waterbome preservatives. The full-cell process steps are listed below:
1. The charge of wood is sealed in the treating cylinder, and an initial vacuum is applied for
approximately half an hour to remove as much air as possible from the wood and from the cylinder;
2. The preservative, either heated or at ambient temperature depending on the system, enters the
cylinder without breaking the vacuum;
3. After the cylinder is filled, the cylinder is pressurized until no more preservative will enter the
wood or until the desired preservative retention is obtained;
4. At the end of the pressure period, the pressure is released, and the preservative is removed from
the cylinder, and
5. A final vacuum may be applied to remove the excess preservative that would otherwise drip from
the wood.
If the wood is steam-conditioned, the preservative is introduced after the vacuum period following
steaming. In segregated systems, the steam conditioning and preservative application steps are conducted in
10.8-2 EMISSION FACTORS 8/99
-------
separate cylinders. The final steps in the process are the unloading of the retort and storage of the treated
wood.
Modified Full-Cell Process -
The modified full-cell process generally is used for the application of waterbome preservatives. This
method is similar to the full-cell process except for the initial vacuum levels. The modified full-cell process
uses less vacuum than the full cell; the vacuum levels are determined by the wood species being treated and
the preservative retention levels desired. The flow diagram shown in Figure 10.8-1 also characterizes the
modified full-cell pressure treating process.
Empty-Cell Process -
The empty-cell process obtains deep preservative penetration with a relatively low net preservative
retention level. If oil preservatives are used, the empty-cell process most likely will be used, provided it will
yield the desired retention level. The Rueping process and the Lowry process are the two most commonly
used empty-cell processes. Both use compressed air to drive out a portion of the preservative absorbed
during the pressure period. Figure 10.8-2 presents a flow diagram for the empty-cell pressure treating
process.
In the Rueping process, compressed air is forced into the treating cylinder containing the charge of
wood to fill the wood cells with air prior to preservative injection. Pressurization times vary with wood
species. For some species only a few minutes of pressurization are required, while more resistant species may
require pressure periods of from 30 minutes to 1 hour. Air pressures used typically range from 172 to 690
kPa (25 to 100 psi) depending on the net preservative retention desired and the resistance of the wood.
After the initial pressurization period, preservative is pumped into the cylinder. As the preservative
enters the treating cylinder, the air escapes into an equalizing or Rueping tank at a rate which maintains the
pressure within the cylinder. When the treating cylinder is filled with preservative, the pressure is raised
above that of the initial air and maintained until the wood will take no more preservative or until enough has
been absorbed to leave the desired preservative retention level after the final vacuum.
After the pressure period, the preservative is removed from the cylinder and surplus preservative is
removed from the wood with a final vacuum. This final vacuum may recover from 20 to 60 percent of the
gross amount of preservative injected. The retort then is unloaded, and the treated wood stored.
The Lowry process is an empty-cell process without the initial air pressure Preservative is pumped
into the treating cylinder without either an initial air pressurization or vacuum, trapping the air that is already
in the wood. After the cylinder is filled with the preservative, pressure is applied and the remainder of the
process is identical to the Rueping process.
The advantage of the Lowry process is that full-cell equipment can be used without the accessories
required by the Rueping process, such as an air compressor, an extra tank for the preservative, or a pump to
force the preservative into the cylinder against the air pressure. However, both processes are used widely and
successfully.
8/99 Wood Products Industry 10.8-3
-------
10.8.2 Emissions2'3-6-9-17
For waterbome preservatives, emissions from wood preserving processes generally are not
significant. For oilbome preservatives, the primary sources of emissions from wood preservation processes
are (1) the treated charge immediately after removal from the treating cylinder, (2) the vacuum system
(conditioning cycle and final vacuum cycle), and (3) displaced air from working tank blow backs. The two
process emission points are the work tank vent and the vacuum system. Figures 10.8-1 and 10.8-2 identify
which process steps are associated with emissions from these two process emission points. Table 10.8-1
presents emission factors for organic pollutant emissions from creosote wood preserving. Table 10.8-2
presents emission factors for inorganic pollutant emissions from chromated copper arsenate wood preserving.
The elevated temperature of the treated charge when it is pulled from the cylinder causes some of the
lower boiling point organic compounds to volatilize as aerosols, forming a white emission plume that
typically dissipates within a few minutes.
Volatile organic compound emissions include those organic compounds present in the wood that are
released when heated during conditioning and treatment, and the polycyclic aromatic hydrocarbons (PAHs)
that are evaporated from the creosote solution and removed from the retort through the vacuum system during
the Boulton (boiling-under-vacuum) process and during the final vacuum applied during the Rueping process.
Creosote emissions can be estimated as the sum of the emissions of the PAHs. Polycyclic aromatic
hydrocarbons are included in the class of compounds referred to as polycyclic organic matter (POM), which is
listed as a hazardous air pollutant in the Clean Air Act.
The emission point for the steaming and vacuum method of conditioning is the vacuum pump system
vent. Vacuum systems include condensers, which are considered part of the process equipment and not
separate emission control devices. The emission points for the Boulton process are the vacuum pump vent
during the vacuum stage of the conditioning process and the work tank vent during the blow back or
preservative withdrawal stage of the conditioning process.
Working tank blow backs also occur at the end of a preservative treatment cycle when the treating
solution is returned to the work tank. The air displaced by the returning solution is vented via a control
device to the atmosphere. In some systems, the displaced air in the work tank is vented back into the
treatment cylinder to fill the head space created as the preservative is withdrawn from the cylinder. In such
systems, there are no emissions associated with blow backs. A problem may arise when the quantity of
preservative being blown back is not monitored closely and air begins to blow up through the work tank.
Volatile compounds are picked up by the air as it bubbles up through the treating solution and are carried out
through the tank vent.
Fugitive emissions of various preservative constituents may occur after the treated wood is removed
from the retort. The fugitive emission rate is a function of the vapor pressure, which is driven by
temperature. Emission rates are greatest immediately after the wood is removed from the retort and generally
decline afterward. Reference 16 describes a method for estimating fugitive emissions from creosote-treated
wood storage as a function of time, temperature, and the effective surface area of the treated wood.
Additional information and a discussion of that method can be found in Reference 17, which is the
background report for this AP-42 section. However, in the absence of a reliable method for estimating the
effective surface area, that method is not presented in this AP-42 section.
In addition to the three primary process emission sources, emissions are generated from waste water
treatment and organic liquid storage tanks. Oilbome wood treatment plants frequently have onsite waste
water treatment facilities designed to separate organic materials from the waste water generated during the
10.8-4 EMISSION FACTORS 8/99
-------
treating process. This wastewater treatment is a potential source of VOC and HAP emissions. Emission
factors for waste water treatment sources are presented in AP-42 Section 4.3, Waste Water Collection,
Treatment And Storage.
Liquid storage tanks for the various preservatives are also sources of VOC and HAPs. Emissions
from these storage tanks are covered in AP-42 Chapter 7, Liquid Storage Tanks.
10.8.3 Controls2-10-12
There are few options for controlling fugitive emission losses from treated charges. Constructing a
ventilation hood to collect VOC emanating from the freshly treated charge is economically infeasible due to
the size of the hood needed for covering the cylinder end and drip pad. The effectiveness of controlling
emissions by using water to cool freshly treated wood by spraying or quenching is questionable. A primary
drawback to water quench systems is that the contaminant is merely transferred to water, resulting in the need
for an effluent treatment system. In addition, water quench systems generate significant amounts of waste
water, which include listed hazardous substances, and, thus, is not desirable.
A 1993 survey of 97 wood preserving facilities found that at least eight facilities used wet scrubbers
for controlling emissions from creosote wood preserving; use of both venturi scrubbers and packed-bed
scrubbers was reported. One facility also reported using a packed-bed scrubber to control VOC emissions
from a PCP wood preserving process. At least two creosote facilities used condensers and one facility used
an incinerator to control VOC emissions from creosote wood preserving. The results of one emissions test on
the incinerator-controlled facility indicated a VOC control efficiency of more than 99 percent for the Boulton
process and first blowback. None of the wood preserving facilities currently in operation use incineration for
emission control. A few facilities control emissions from creosote wood preserving processes by means of a
knock-out tank followed by a venturi scrubber. The results of an emission test on such a system indicated a
VOC control efficiency of 75 percent.
Odorous emissions from the steam jet vacuum system suggest that a single-pass water-cooled
condenser may not condense all of the organics in the exhaust. One option for correcting this problem is to
install a larger condenser capable of further reducing the organic content in the vapor. A properly sized
condenser with adequate cooling water will condense virtually all of the organics in the exhaust stream
Another option is to modify the vacuum system to include two steam jet ejectors in series with a barometric
(direct contact) intercondenser between them. In this system, the barometric intercondensers condense the oily
vapors in the steam and remove them with the intercondensed water. A third option is to replace the steam jet
ejectors with a vacuum pump and duct the exhaust vapors to an activated carbon adsorption system or to an
afterburner. Both are efficient means for removing organic compounds from the exhaust gas.
Working tank blow back vapors can be controlled by bubbling the vapors through water or through a
water spray before venting to the atmosphere. However, the effectiveness of these systems will deteriorate if
the water is allowed to reach saturation and is not changed periodically. Another option for controlling these
vapors is to incinerate them in an afterburner along with the vacuum system exhaust. However, incinerators
are not in use currently at any domestic wood preserving facilities.
8/99 Wood Products Industry 10.8-5
-------
EMISSION
POINTS
PROCESS
i) WORK TANK EMISSIONS
D VACUUM SYSTEM EMISSIONS
3) POTENTIAL SOURCE OF
FUGITIVE VOC AND PM EMISSIONS
4) OTHER VOC EMISSION POINT
NOTE' PROCESS EMISSION POINTS ARE THE WORK TANK VENT AND VACUUM SYSTEM
Figure 10.8-1. Row diagram of the full-cell and modified full-cell pressure treating processes.
10.8-6 EMISSION FACTORS 8/99
-------
EMISSION ©
POINTS :
(§) [*• KILN
TANK
1 "
J ^
STORAGE : nrrnrn-
PILES * nETUHl
PROCESS
STEPS
i
4 T
VACUUM
PUMP
RECEIVING
AND STORAGE
(T^
SEASONING KILN DRYING -'
\
RETORT
LOADING
1
AIR
PRESSURIZATION
4
_i
@ i
i !
^ STORAGE
* YARD
»
4
RETORT
LOADING
1 i
AJ
STEAMING BOILING UNDER
AND VACUUM
VACUUM (BOULTON)
,
•^ PRESERVATIVE
FILLING/
AIR RELEASE
,
PRESERVATIVE
PRESSURE
INJECTION
CD
4
1
2l PRESERVATIVE
RETURN TO
WORK TANK
,
DJ
A
L _ . VACUUM •
TREATED WOOD
UNLOADING AND
STORAGE
I
0 WORK TANK EMISSIONS
(|) VACUUM SYSTEM EMISSIONS
(3) POTENTIAL SOURCE OF
0 FUGITIVE VOC AND PM EMISSIONS
* 0 OTHER VOC EMISSION POINT
NOTE: PROCESS EMISSION POINTS ARE THE WORK TANK VENT AND VACUUM SYSTEM.
8/99
Figure 10.8-2. Flow diagram for the empty-cell pressure treating process.
Wood Products Industry
10.8-7
-------
TABLE 10.8.-1. EMISSION FACTORS FOR CREOSOTE EMPTY-CELL WOOD PRESERVING3
EMISSION FACTOR RATING: E
Process
Treatment cycle without conditioning,
uncontrolled emissions
(SCC: 3-07-005-30)
(Includes steps B, C, and D shown in
Figure 10.8-2)
Treatment cycle with conditioning by
Boulton process, uncontrolled emissions
(SCC: 3-07-005-40)
(Includes steps A, B, C, and D shown in
Figure 10.8-2)
CASRN
83-32-9
208-96-8
120-12-7
56-55-3
205-99-2
207-08-9
50-32-8
86-74-8
218-01-9
132-64-9
206-44-0
86-73-7
91-20-3
85-01-8
129-00-0
83-32-9
208-96-8
120-12-7
56-55-3
205-99-2
207-08-9
50-32-8
86-74-8
218-01-9
132-64-9
204-44-0
86-73-7
91-20-3
85-01-8
129-00-0
Pollutant
vocb
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Carbazole
Chrysene
Dibenzofuran
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
vocb
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Carbazole
Chrysene
Dibenzofuran
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
Emission Factor
7.4 x ID"4
6.3 x 10'7
1.7X10'6
1.6X10'8
1.7 x 10'8
1.6X10'8
6.0 x 10'9
8.2 x lO'9
3.6 x 10'7
8.4 x 10'9
l.SxlO'6
8.6 x 10'8
7.8 x 10'8
4.6 x 10'6
2.8 x 10'7
7.3 x 10'8
5.8 x 10'3
9.9 x 10'6
2.8 x 10'5
1.3 x 10'7
1.3X10'7
1.3 xlO"7
4.8 x 10'8
6.5 x 10'8
2.9 x 10-6
6.7 x 10'8
3.5 x 10'5
6.8 x 10'7
3.9 x 10-6
7.9 x 10'5
1.9xlO'6
5.8 x 10'7
10.8-8
EMISSION FACTORS
8/99
-------
Table 10.8-1 (cont).
a References 12 and 16, except where noted. Factors are in units of pounds per cubic foot (Ib/ft3)of wood
treated. To convert to kilograms per cubic meter (kg/m3), multiply by 16. CASRN = Chemical Abstract
Services Registry Number. SCC = source classification code.
b References 10 and 16. Volatile organic compounds as propane, based on Method 25A test results.
8/99 Wood Products Industry 10.8-9
-------
Table 10.8-2. EMISSION FACTORS FOR INORGANIC POLLUTANT EMISSIONS
FROM CHROMATED COPPER ARSENATE EMPTY-CELL WOOD PRESERVING3
EMISSION FACTOR RATING: E
Source
Treatment cycle with conditioning,
uncontrolled emissions
(SCC 3-07-005-43)
CASRN
7440-47-3
7440-50-8
Name
Chromium
Copper
Emission Factor
1.4xlO'9
1.9xl
-------
References For Section 10.8
1. The 1995 Wood Preserving Industry Production Statistical Report, American Wood Preservers
Institute, Vienna, VA, September 1996.
2. C. C. Vaught and R. L. Nicholson, Evaluation Of Emission Sources From Creosote Wood Treatment
Operations, EPA-450/3-89-028, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 1989.
3. Electronic communication (e-mail) from Nick Bock, Kerr-McGee Chemical Corporation, to George
Parris, American Wood Preservers Institute, September 17,1998.
4. American Wood-Preservers' Association Books Of Standards, 1991. American Wood Preservers'
Association, Woodstock, MD, 1992.
5. Written communication from Martin Wikstrom, American Wood Preservers Institute, to Dallas Safriet,
U. S. Environmental Protection Agency, Research Triangle Park, NC, February 18, 1994.
6. Written communication from Gene Bartlow, American Wood Preservers Institute, Vienna, VA, to
Dallas Safriet, U. S. Environmental Protection Agency, Research Triangle Park, NC, January 10, 1997.
7. Written communication from Carlton Degges, Vulcan Chemicals, Birmingham, AL, to Dallas Safriet,
U. S. Environmental Protection Agency, Research Triangle Park, NC, August 9, 1996.
8. Wood Preserving Resource Conservation And Recovery Act Compliance Guide, A Guide To Federal
Environmental Regulation, EPA-305-B-96-001, U. S. Environmental Protection Agency,
Washington, D.C., June 1996.
9. Electronic communication (e-mail) from George Parris, American Wood Preservers Institute, to
Richard Marinshaw, Midwest Research Institute, September 17, 1998.
10. Draft Industry Profile, technical memorandum from B. Gatano, Research Triangle Institute, to Eugene
Grumpier, U. S. Environmental Protection Agency, Research Triangle Park, NC, August 2, 1993.
11. Wood Treatment Plant Emission Test Report, Kerr-McGee Chemical Corporation, Avoca,
Pennsylvania, EMB Report 94-WDT-01, U. S. Environmental Protection Agency, Research Triangle
Park, NC, September 1994.
12. Gaseous Organic Compound Emission Study, Naphthalene Knock-Out Tank And Water Scrubber,
Birmingham Wood, Inc., Warrior, Alabama, Allied Signal, Inc., April 12 and 13, 1994, 1'1'L, Inc.,
Tuscaloosa, AL, May 1994.
13. Final Emission Data Report: Emission Testing Program At Koppers Superfund Site, Oroville, CA,
prepared for U. S. Environmental Protection Agency, Region IX, by Ebasco Services, Incorporated,
December 1989.
14. Koppers Industries, Incorporated, Pittsburgh, Pennsylvania, Susquehanna Wood Treating Facilities
Vacuum Pump Emissions Study, Chester Environmental, Pittsburgh, PA, April 1994.
8/99 Wood Products Industry 10.8-11
-------
15. Koppers Industries, Incorporated, Oroville, CA, AB 2588 Emissions Test Program, Test Date:
October 8 through 12, 1990, Best Environmental, Hayward, CA, November 14,1990.
16. Calculated Emissions From Creosote-Treated Wood Products (Cross-Ties And Poles) , AquaAeTer,
Brentwood, TN, and American Wood Preservers Institute, Vienna, VA, October 13, 1994.
17. Emission Factor Documentation For AP-42 Section 10.8, Wood Preserving, Final Report,
U. S. Environmental Protection Agency, Research Triangle Park, NC, August 1999.
10.8-12 EMISSION FACTORS 8/99
-------
11.9 Western Surface Coal Mining
11.9.1 General1
There are 12 major coal fields in the western states (excluding the Pacific Coast and Alaskan
fields), as shown in Figure 11.9-1. Together, they account for more than 64 percent of the surface minable
coal reserves in the United States.2 The 12 coal fields have varying characteristics that may influence
fugitive dust emission rates from mining operations including overburden and coal seam thicknesses and
structure, mining equipment, operating procedures, terrain, vegetation, precipitation and surface moisture,
wind speeds, and temperatures. The operations at a typical western surface mine are shown in
Figure 11.9-2. All operations that involve movement of soil or coal, 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 that 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 tipple, 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 prepared for revegetation by furrowing, mulching, etc. From the time an area is disturbed until the new
vegetation emerges, all disturbed areas are subject to wind erosion.
11.9.2 Emissions
Predictive emission factor equations for open dust sources at western surface coal mines are
presented in Tables 11.9-1 and 11.9-2. Each equation applies to a single dust-generating activity, such as
vehicle traffic on haul roads. The predictive equation explains much of the observed variance in emission
factors by relating emissions to three sets of source parameters: (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).
10/98 Mineral Products Industry 11.9-1
-------
cow.
LICKXTE
SUBIJTUNINOUS
reck
VtttB
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11.9-2
Figure 11.9-1. Coal fields of the western United States.3
EMISSION FACTORS
10/98
-------
if!
-------
The equations may be used to estimate particulate emissions generated per unit of source extent or
activity (e. g., distance traveled by a haul truck or mass of material transferred). 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 11.9-1 and 11.9-2, the assigned quality ratings apply within the ranges of source
conditions that were tested in developing the equations given in Table 11.9-3. However, the equations
should be derated 1 letter value (e. g., A to B) if applied to eastern surface coal mines.
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 ratings of the equations are to be applicable. For example, actual silt content
of coal or overburden measured at a facility should be used instead of estimated values. In the event that
site-specific values for correction parameters cannot be obtained, the appropriate geometric mean values
from Table 11.9-3 may be used, but the assigned quality rating of each emission factor equation should be
reduced by 1 level (e. g., A to B).
Emission factors for open dust sources not covered in Table 11.9-3 are in Table 11.9-4. These
factors were determined through source testing at various western coal mines.
The factors in Table 11.9-4 for mine locations I through V were developed for specific
geographical areas. Tables 11.9-5 and 11.9-6 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 11.9-4 for train or truck
loading and for truck or scraper unloading, two empirically derived emission factor equations are presented
in Section 13.2.4 of this document. Each equation was developed for a source operation (i. e., batch drop
and continuous drop, respectively) comprising a single dust-generating mechanism that crosses industry
lines.
Because the predictive equations allow emission factor adjustment to specific source conditions,
the equations should be used in place of the single-valued factors in Table 11.9-4 for the sources identified
above, if emission estimates 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. Caution must be exercised so that only the
unbound (sorbed) moisture (i. e., not any bound moisture) is used in determining the moisture content for
input to the Chapter 13 equations.
11.9-4 EMISSION FACTORS 10/98
-------
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7/98
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Mineral Products Industry
11.9-7
-------
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EMISSION FACTORS
7/98
-------
Table 11.9-3 (Metric And English Units). TYPICAL VALUES FOR CORRECTION
FACTORS APPLICABLE TO THE PREDICTIVE EMISSION FACTOR EQUATIONS3
Source
Blasting
Coal loading
Bulldozers
Coal
Overburden
Dragline
Scraper
Grader
Haul truck
Correction Factor
Area blasted
Area blasted
Moisture
Moisture
Silt
Moisture
Silt
Drop distance
Drop distance
Moisture
Silt
Weight
Weight
Speed
Speed
Silt content
Moisture
Weight
Weight
Number Of
Test
Samples
17
17
7
3
3
8
8
19
19
7
10
15
15
7
61
60
61
61
Range
100 - 6,800
1100- 73,000
6.6 - 38
4.0 - 22.0
6.0- 11.3
2.2 - 16.8
3.8- 15.1
1.5-30
5-100
0.2 - 16.3
7.2 - 25.2
33-64
36-70
8.0 - 19.0
5.0- 11.8
1.2- 19.2
0.3- 20.1
20.9 - 260
23.0 - 290
Geometric
Mean
1,590
17,000
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
4.3
2.4
110
120
Units
m2
ft2
%
%
%
%
%
m
ft
%
%
Mg
ton
kph
mph
%
%
mg
ton
' Reference 1,6.
7/98
Mineral Products Industry
11.9-9
-------
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EMISSION FACTORS
7/98
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7/98
Mineral Products Industry
11.9-11
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13.2.2 Unpaved Roads
13.2.2.1 General
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.
13.2.2.2 Emissions Calculation And Correction Parameters1"6
The quantity of dust emissions from a given segment of unpaved road varies linearly with the
volume of traffic. Field investigations also have shown that emissions depend on source parameters that
characterize the condition of a particular road and the associated vehicle traffic. Characterization of these
source parameters allow for "correction" of emission estimates to specific road and traffic conditions.
Dust emissions from unpaved roads have been found to vary directly with the fraction of silt
(particles smaller than 75 micrometers [/Ltm] 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. A summary of this method is contained in Appendix C of AP-42. Table 13.2.2-1
summarizes measured silt values for industrial and public unpaved roads. It should be noted that the
ranges of silt content vary over two orders of magnitude. Therefore, the use of data from this table can
potentially introduce considerable error. Use of this data is strongly discouraged when it is feasible to
obtain locally gathered data.
Since the silt content of a rural dirt road will vary with geographic location, it should be measured
for use in projecting emissions. As a conservative approximation, the silt content of the parent soil in the
area can be used. Tests, however, show that road silt content 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.
The PM-10 and TSP emission factors presented below are the outcomes from stepwise linear
regressions of field emission test results of vehicles traveling over unpaved surfaces. The results from
180 PM-10 and 92 TSP field tests were used to develop the predictive emission factor expressions. Due to.
a limited amount of information available for PM-2.5, the expression for that size range has been scaled
against the result for PM-10. Consequently, the quality rating for the PM-2.5 factor is lower than that for
the PM-10 expression. The background document for AP-42 Section 13.2.2 (Reference 6) fully describes
the process used to develop and validate the emission factor expressions.
9/98 Miscellaneous Sources 13.2.2-1
-------
Table 13.2.2-1. TYPICAL SILT CONTENT VALUES OF SURFACE MATERIAL
ON INDUSTRIAL AND RURAL UNPAVED ROADSa
Industry
Copper smelting
Iron and steel production
Sand and gravel processing
Stone quarrying and processing
Taconite mining and processing
Western surface coal mining
Construction sites
Lumber sawmills
Municipal solid waste landfills
Publicly accessible roads
Road Use Or
Surface Material
Plant road
Plant road
Plant road
Material storage
area
Plant road
Haul road to/from
pit
Service road
Haul road to/from
pit
Haul road to/from
pit
Plant road
Scraper route
Haul road
(freshly graded)
Scraper routes
Log yards
Disposal routes
Gravel/crushed
limestone
Dirt (i.e., local
material
compacted, bladed,
and crowned)
Plant
Sites
1
19
1
1
2
4
1
1
3
2
3
2
7
2
4
9
8
No. Of
Samples
3
135
3
1
10
20
8
12
21
2
10
5
20
2
20
46
24
Silt Content (%)
Range
16-19
0.2 - 19
4.1 -6.0
_
2.4 - 16
5.0-15
2.4-7.1
3.9-9.7
2.8- 18
4.9-5.3
7.2 - 25
18-29
0.56-23
4.8-12
2.2-21
0.1-15
0.83-68
Mean
17
6.0
4.8
7.1
10
8.3
4.3
5.8
8.4
5.1
17
24
8.5
8.4
6.4
6.4
11
"References 1,5-16.
13.2.2-2
EMISSION FACTORS
9/98
-------
The following empirical expression may be used to estimate the quantity in pounds (Ib) of
size-specific particulate emissions from an unpaved road, per vehicle mile traveled (VMT):
E =
k (s/12)a(W/3)b
(M/0.2)c
(1)
where k, a, b and c are empirical constants (Reference 6) given below and
E = size-specific emission factor (Ib/VMT)
s = surface material silt content (%)
W = mean vehicle weight (tons)
M = surface material moisture content (%)
The source characteristics s, W and M are referred to as correction parameters for adjusting the emission
estimates to local conditions. The metric conversion from Ib/VMT to grams (g) per vehicle kilometer
traveled (VKT) is as follows:
1 Ib/VMT = 281.9 g/VKT
The constants for Equation 1 based on the stated aerodynamic particle sizes are shown in Table 13.2.2-2.
Table 13.2.2-2. CONSTANTS FOR EQUATION 1
Constant
k (Ib/VMT)
a
b
c
Quality rating
PM-2.5
0.38
0.8
0.4
0.3
C
PM-10
2.6
0.8
0.4
0.3
B
PM-30"
10
0.8
0.5
0.4
B
"Assumed equivalent to total suspended particulate (TSP).
Table 13.2.2-2 also contains the quality ratings for the various size-specific versions of Equation 1. The
equation retains the assigned quality rating, if applied within the ranges of source conditions, shown in
Table 13.2.2-3, that were tested in developing the equation:
Table 13.2.2-3. RANGE OF SOURCE CONDITIONS USED IN DEVELOPING EQUATION 1
Surface Silt
Content, %
1.2-35
Mean Vehicle Weight
Mg
1.4-260
ton
1.5-290
Mean Vehicle Speed
km/hr
8-88a
mph
5-55a
Mean No.
of Wheels
4-7a
Surface
Moisture
Content, %
0.03-20
a See discussion in text.
As noted earlier, Equation 1 was developed from tests of traffic on unpaved surfaces, either
uncontrolled or watered. Unpaved roads have a hard, generally nonporous surface that usually dries
quickly after a rainfall or watering, because of traffic-enhanced natural evaporation. (Factors influencing
9/98
Miscellaneous Sources
13.2.2-3
-------
how fast a road dries are discussed in Section 13.2.2.3, below.) The quality ratings given above pertain to
the mid-range of the measured source conditions for the equation. A higher mean vehicle weight and a
higher than normal traffic rate may be justified when performing a worst-case analysis of emissions from
unpaved roads.
It is important to note that the vehicle-related source conditions refer to the average weight, speed,
and number of wheels for all vehicles traveling the road. For example, if 98 percent of traffic on the road
are 2-ton cars and trucks while the remaining 2 percent consists of 20-ton trucks, then the mean weight is
2.4 tons. More specifically, Equation 1 is not intended to be used to calculate a separate emission factor
for each vehicle class within a mix of traffic on a given unpaved road. That is, in the example, one should
not determine one factor for the 2-ton vehicles and a second factor for the 20-ton trucks. Instead, only one
emission factor should be calculated that represents the "fleet" average of 2.4 tons for all vehicles traveling
the road.
Furthermore, although mean vehicle speed and the mean number of wheels do not explicitly appear
in the predictive equation, these variables should be considered when determining quality ratings. During
the validation of Equation 1, it was found that the predictive equation tends to overpredict emissions for
very slow mean vehicle speeds.
The background document (Reference 6) discusses this tendency for very slow vehicles speeds.
The background document further notes that no bias is evident for mean vehicle speeds of at least 15 mph.
In the case of a mean vehicle speed less than 15 mph. Equation 1 could be used to conservatively
estimate the amount of emissions due to traffic over the unpaved surface. Should one wish to account for
the tendency for Equation 1 to overestimate at low speeds, it is recommended that Equation 1 be multiplied
by (S/15), where S is the average vehicle speed (mph) and S< 15 mph. Again, note that this applies only to
situations in which the average vehicle speed is less than 15 mph. Furthermore, if Equation 1 is multiplied
by (S/15), then the quality rating of the emission estimate should be downgraded by at least one letter.
Moreover, to retain the quality ratings when addressing a group of unpaved roads, 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 and moisture contents are given in AP-42 Appendices C. 1
and C.2. Vehicle-related parameters should be developed by recording visual observations of traffic. In
some cases, vehicle parameters for industrial unpaved roads can be determined by reviewing maintenance
records or other information sources at the facility.
In the event that site-specific values for correction parameters cannot be obtained, then default
values may be used. A default value of 2.2 tons is recommended for the mean vehicle weight on publicly
accessible unpaved roads. (It is assumed that readers addressing industrial roads have access to the
information needed to develop average vehicle information for their facility.) In the absence of site-specific
silt content information, an appropriate mean value from Table 13.2.2-1 may be used as a default value,
but the quality rating of the equation is reduced by two letters. Because of significant differences found
between different types of road surfaces and between different areas of the country, use of the default
moisture content value of 0.2 percent for dry conditions is discouraged. The quality rating should be
downgraded two letters when the default moisture content value is used.
The effect of routine watering to control emissions from unpaved roads is discussed below in
Section 13.2.2.3, "Controls". However, all roads are subject to some natural mitigation because of rainfall
and other precipitation. Equation 1 can be extrapolated to annual average uncontrolled conditions (but
13.2.2-4 EMISSION FACTORS 9/98
-------
including natural mitigation) under the simplifying assumption that annual average emissions are inversely
proportional to the number of days with measurable (more than 0.254 mm [0.01 inch]) precipitation:
where s, W, k, a, b and c are as given earlier and
Eext = annual size-specific emission factor extrapolated for natural mitigation, Ib/VMT
M,^ = surface material moisture content under dry, uncontrolled conditions, %
p = number of days with at least 0.254 mm (0.01 in) of precipitation per year (see below)
Figure 13.2.2-1 gives the geographical distribution for the mean annual number of "wet" days for the
United States. Although the use of information from this table is reasonable for estimating an average
emission factor, it would not be reasonable to use this information to estimate an actual emission factor for
a specific year. Reported meteorological information should be used for estimating actual emission factors.
It is emphasized that the moisture content to be used in Equation 2 — M^ ~ must reference dry.
worst-case conditions. In the absence of the appropriate site-specific information, the default value of
0.2 percent should be used in Equation 2.
Equation 2 provides an estimate that accounts for precipitation on an annual average basis for the
purpose of inventorying emissions. It should be noted that Equation 2 does not account for differences in
the temporal distributions of the rain events, the quantity of rain during any event, or the potential for the
rain to evaporate from the road surface. In the event that a finer temporal and spatial resolution is desired
for inventories of public unpaved roads, estimates can be based on a more complex set of assumptions.
These assumptions include:
1. The moisture content of the road surface material is increased in proportion to the quantity of
water added;
2. The moisture content of the road surface material is reduced in proportion to the Class A pan
evaporation rate;
3. The moisture content of the road surface material is reduced in proportion to the traffic volume;
and
4. The moisture content of the road surface material varies between the extremes observed in the
area. The CHIEF Web site (http://www.epa.gov/ttn/chief/ap42back.html) has a file which contains a
spreadsheet program for calculating emission factors which are temporally and spatially resolved.
Information required for use of the spreadsheet program includes monthly Class A pan evaporation values,
hourly meteorological data for precipitation, humidity and snow cover, vehicle traffic information, and road
surface material information.
It is emphasized that the simple assumption underlying Equation 2 and the more complex set of
assumptions underlying the use of the procedure which produces a finer temporal and spatial resolution
have not been verified in any rigorous manner. For this reason, the quality ratings for either approach
should be downgraded one letter from the rating that would be applied to Equation 1.
9/98 Miscellaneous Sources 13.2.2-5
-------
13.2.2.3 Controls18-22
A wide variety of options exist to control emissions from unpaved roads. Options fall into the
following three groupings:
1. Vehicle restrictions that limit the speed, weight or number of vehicles on the road;
2. Surface improvement, by measures such as (a) paving or (b) adding gravel or slag to a dirt road;
and
3. Surface treatment, such as watering or treatment with chemical dust suppressants.
Available control options span broad ranges in terms of cost, efficiency, and applicability. For example,
traffic controls provide moderate emission reductions (often at little cost) but are difficult to enforce.
Although paving is highly effective, its high initial cost is often prohibitive. Furthermore, paving is not
feasible for industrial roads subject to very heavy vehicles and/or spillage of material in transport. Watering
and chemical suppressants, on the other hand, are potentially applicable to most industrial roads at moderate
to low costs. However, these require frequent reapplication to maintain an acceptable level of control.
Chemical suppressants are generally more cost-effective than water but not in cases of temporary roads
(which are common at mines, landfills, and construction sites). In summary, then, one needs to consider not
only the type and volume of traffic on the road but also how long the road will be in service when developing
control plans.
Vehicle restrictions. These measures seek to limit the amount and type of traffic present on the road
or to lower the mean vehicle speed. For example, many industrial plants have restricted employees from
driving on plant property and have instead instituted bussing programs. This eliminates emissions due to
employees traveling to/from their worksites. Although the heavier average vehicle weight of the busses
increases the base emission factor, the decrease in vehicle-miles-traveled results in a lower overall emission
rate.
Although vehicle speed does not appear as a correction parameter, it is obvious to anyone who has
driven on an unpaved road that (visible) emissions increase with vehicle speed. Accordingly, speed reduction
is a clearly viable control measure. However, as with the source parameters that do appear in Equation 1, the
control measure must effectively reduce the fleet average speed. In order to substantially reduce the speed of
all vehicles, this control option is most applicable to rural public roads. However, effective enforcement of
the new speed limit may prove problematic.
Currently available short-term tests suggest that the control efficiency afforded by speed reduction
should be considered as linear. Thus, if the average speed is effectively reduced by 30 percent (e.g., from 50
to 35 mph), then a control efficiency of 30 percent should be applied to the emission factor. The background
document discusses how past testing programs used "captive" traffic to tightly control vehicular
characteristics. These tests involve very short periods (1 to 2 hr) of increased or reduced travel speeds.
Under these conditions, it was found that emissions depend upon speed raised to a power between 1 and 2.
However, exploratory analysis of the data supporting the equation in this section indicated that emissions
were poorly correlated with speed raised to the power of approximately 0.3. As a result, it is
believed that if the long-term, average speed is reduced on an unpaved road, the road surface silt content can
be expected to change. In other words, the silt content will reach a new equilibrium condition as the grinding
of material is balanced by the emission process. It is strongly recommended that any prospective emission
reduction credit based upon speed reduction be based upon the ratio of speeds raised to the
0.3 power. After 6 months operation at the slower speed a new road surface sample should be collected
13.2.2-6 EMISSION FACTORS 9/98
-------
uo
-------
and analyzed (in the manner described in Appendices C.I and C.2). The new surface silt content should
then be used in Equation 1 for calculation of a new uncontrolled emission factor, without further
adjustment for speed.
Surface improvements. Control options in this category alter the road surface. As opposed to the
"surface treatments" discussed below, improvements are relatively "permanent" and do not require periodic
retreatment.
The most obvious surface improvement is paving an unpaved road. This option is quite expensive
and is probably most applicable to relatively short stretches of unpaved road with at least several hundred
vehicle passes per day. Furthermore, if the newly paved road is located near unpaved areas or is used to
transport material, it is essential that the control plan address routine cleaning of the newly paved road
surface.
The control efficiencies achievable by paving can be estimated by comparing emission factors for
unpaved and paved road conditions. The predictive emission factor equation for paved roads, given in
Section 13.2.1, 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 unpaved shoulders (berms) also must be taken into account in estimating the
control efficiency of paving.
Other improvement methods cover the road surface with another material that has a lower silt
content. Examples include placing gravel or slag on a dirt road. Control efficiency can be estimated by
comparing the emission factors obtained using the silt contents before and after improvement. The silt
content of the road surface should be determined after 3 to 6 months rather than immediately following
placement. Control plans should address regular maintenance practices, such as grading, to retain larger
aggregate on the traveled portion of the road.
Surface treatments refer to control options which require periodic reapplication. Treatments fall
into the two main categories of (a) "wet suppression" (i. e., watering, possibly with surfactants or other
additives), which keeps the road surface wet to control emissions and (b) "chemical stabilization/
treatment", which attempts to change the physical characteristics of the surface. The necessary
reapplication frequency varies from several minutes for plain water under summertime conditions to several
weeks or months for chemical dust suppressants.
Watering increases the moisture content, which conglomerates particles and reduces their
likelihood to become suspended when vehicles pass over the surface. The control efficiency depends on
how fast the road dries after water is added. This in turn depends on (a) the amount (per unit road surface
area) of water added during each application; (b) the period of time between applications; (c) the weight,
speed and number of vehicles traveling over the watered road during the period between applications; and
(d) meteorological conditions (temperature, wind speed, cloud cover, etc.) that affect evaporation during the
period.
Given the complicated nature of how the road dries, characterization of emissions from watered
roadways is best done by collecting material samples at various times between water truck passes.
(Appendices C. 1 and C.2 present the sampling and analysis procedures.) The time-averaged moisture
content is then substituted into Equation 1. Samples that reflect average conditions during the watering
cycle can take the form of either a series of samples between water applications or a single sample at the
midpoint. It is essential that samples be collected during periods with active traffic on the road. Finally,
13.2.2-8 EMISSION FACTORS 9/98
-------
because of different evaporation rates, it is recommended that samples be collected at various times during
the year. If only one set of samples is to be collected, these must be collected during hot, summertime
conditions.
When developing watering control plans for roads that do not yet exist, it is strongly recommended
that the moisture cycle be established by sampling similar roads in the same geographic area. If the
moisture cycle cannot be established by similar roads using established watering control plans, the more
complex methodology used to estimate the mitigation of rainfall and other precipitation can be used to
estimate the control provided by routine watering. An estimate of the maximum daytime Class A pan
evaporation (based upon daily evaporation data published in the monthly Climatological Data for the state
by the National Climatic Data Center) should be used to insure that adequate watering capability is
available during periods of highest evaporation. The hourly precipitation values in the spreadsheet should
be replaced with the equivalent inches of precipitation (where the equivalent of 1 inch of precipitation is
provided by an application of 5.6 gallons of water per square yard of road). Information on the long term
average annual evaporation and on the percentage that occurs between May and October was published in
the Climatic Atlas (Reference 16). Figure 13.2.2-2 presents the geographical distribution for "Class A pan
evaporation" throughout the United States. Figure 13.2.2-3 presents the geographical distribution of the
percentage of this evaporation that occurs between May and October. The U. S. Weather Bureau Class A
evaporation pan is a cylindrical metal container with a depth of 10 inches and a diameter of 48 inches.
Periodic measurements are made of the changes of the water level.
The above methodology should be used only for prospective analyses and for designing watering
programs for existing roadways. The quality rating of an emission factor for a watered road that is based
on this methodology should be downgraded two letters. Periodic road surface samples should be collected
and analyzed to verify the efficiency of the watering program.
As opposed to watering, chemical dust suppressants have much less frequent reapplication
requirements. These materials suppress emissions by changing the physical characteristics of the existing
road surface material. Many chemical unpaved road dust suppressants form a hardened surface that binds
particles together. After several applications, a treated road often resembles a paved road except that the
surface is not uniformly flat. Because the improved surface results in more grinding of small particles, the
silt content of loose material on a highly controlled surface may be substantially higher than when the
surface was uncontrolled. For this reason, Equation 1 cannot be used to estimate emissions from
chemically stabilized roads. Should the road be allowed to return to an uncontrolled state with no visible
signs of large-scale cementing of material, Equation 1 could then be used to obtain conservatively high
emission estimates.
The control effectiveness of chemical dust suppressants appears to depend on (a) the dilution rate
used in the mixture; (b) the application rate (volume of solution per unit road surface area); (c) the time
between applications; (d) the size, speed and amount of traffic during the period between applications; and
(e) meteorological conditions (rainfall, freeze/thaw cycles, etc.) during the period. Other factors that affect
the performance of dust suppressants include other traffic characteristics (e. g., cornering, track-on from
unpaved areas) and road characteristics (e. g., bearing strength, grade). The variabilities in the above
factors and differences between individual dust control products make the control efficiencies of chemical
dust suppressants difficult to estimate. Past field testing of emissions from controlled unpaved roads has
shown that chemical dust suppressants provide a PM-10 control efficiency of about 80 percent when
applied at regular intervals of 2 weeks to 1 month.
9/98 Miscellaneous Sources 13.2.2-9
-------
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13.2.2-10
EMISSION FACTORS
9/98
-------
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Petroleum resin products historically have been the dust suppressants (besides water) most widely
used on industrial unpaved roads. Figure 13.2.2-4 presents a method to estimate average control
efficiencies associated with petroleum resins applied to unpaved roads.20 Several items should be noted:
1. The term "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 13.2.2-4 presents control efficiency values
averaged over two common application intervals, 2 weeks and 1 month. Other application intervals will
require interpolation.
3. Note that zero efficiency is assigned until the ground inventory reaches 0.05 gallon per square
yard (gal/yd2). Requiring a minimum ground inventory ensures that one must apply a reasonable amount
of chemical dust suppressant to a road before claiming credit for emission control. Recall that the ground
inventory refers to the amount of petroleum resin concentrate rather than the total solution.
As an example of the application of Figure 13.2.2-4, suppose that the equation was used to
estimate an emission factor of 7.1 Ib/VMT for PM-10 from a particular road. Also, suppose that, starting
on May 1, the road is treated with 0.221 gal/yd2 of a solution (1 part petroleum resin to 5 parts water) on
the first of each month through September. Then, the average controlled emission factors, shown in
Table 13.2.2-4, are found.
Table 13.2-2-4. EXAMPLE OF AVERAGE CONTROLLED EMISSION FACTORS
FOR SPECIFIC CONDITIONS
Period
May
June
July
August
September
Ground Inventory,
gal/yd2
. 0.037
0.073
0.11
0.15
0.18
Average Control
Efficiency, %a
0
62
68
74
80
Average Controlled
Emission Factor,
Ib/VMT
7.1
2.7
2.3
1.8
1.4
From Figure 13.2.2-4, < 10 /im. Zero efficiency assigned if ground inventory is less than 0.05 gal/yd2.
1 Ib/VMT = 281.9 g/VKT. 1 gal/yd2 = 4.531 L/m2.
Besides petroleum resins, other newer dust suppressants have also been successful in controlling
emissions from unpaved roads. Specific test results for those chemicals, as well as for petroleum resins
and watering, are provided in References 18 through 21.
13.2.2-12
EMISSION FACTORS
9/98
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9/98
Miscellaneous Sources
13.2.2-13
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13.2.2.4 Updates Since The Fifth Edition
The Fifth Edition was released in January 1995. Revisions to this section since that date are
summarized below. For further detail, consult the background report for this section (Reference 6).
October 1998 (Supplement E)~This was a major revision of this section. Significant changes to
the text and the emission factor equations were made.
References For Section 13.2.2
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, 70(10): 1046-1048, October 1976.
3. R. O. McCaldin and K. J. Heidel, "Paniculate 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. G. Muleski, Unpaved Road Emission Impact, Arizona Department of Environmental Quality,
Phoenix, AZ, March 1991.
6. Emission Factor Documentation For AP-42, Section 13.2.2, Unpaved Roads, Final Report,
Midwest Research Institute, Kansas City, MO, September 1998.
7. T. Cuscino, Jr., et al., TacOnite Mining Fugitive Emissions Study, Minnesota Pollution Control
Agency, Roseville, MM, June 1979.
8. Improved Emission Factors For Fugitive Dust From Western Surface Coal Mining Sources,
2 Volumes, EPA Contract No. 68-03-2924, Office of Air Quality Planning and Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC.
9. 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.
10. Size Specific Emission Factors For Uncontrolled Industrial And Rural Roads, EPA Contract
No. 68-02-3158, Midwest Research Institute, Kansas City, MO, September 1983.
11. C. Cowherd, Jr., and P. Englehart, Size Specific Paniculate Emission Factors For Industrial And
Rural Roads, EPA-600/7-85-038, U. S. Environmental Protection Agency, Cincinnati, OH,
September 1985.
12. PM-10 Emission Inventory Of Landfills In The Lake Calumet Area, EPA Contract 68-02-3891,
Work Assignment 30, Midwest Research Institute, Kansas City, MO, September 1987.
13.2.2-14 EMISSION FACTORS 9/98
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13. Chicago Area Paniculate Matter Emission Inventory — Sampling And Analysis, EPA Contract
No. 68-02-4395, Work Assignment 1, Midwest Research Institute, Kansas City, MO, May 1988.
14. PM-10 Emissions Inventory Data For The Maricopa And Pima Planning Areas, EPA Contract
No. 68-02-3888, Engineering-Science, Pasadena, CA, January 1987.
15. Oregon Fugitive Dust Emission Inventory, EPA Contract 68-DO-0123, Midwest Research
Institute, Kansas City, MO, January 1992.
16. Climatic Atlas Of The United States, U. S. Department Of Commerce, Washington, DC,
June 1968.
17. National Climatic Data Center, Solar And Meteorological Surface Observation Network 1961-
1990; 3 Volume CD-ROM. Asheville, NC, 1993.
18. C. Cowherd, Jr. et al, Control Of Open Fugitive Dust Sources, EPA-450/3-88-008,
U. S. Environmental Protection Agency, Research Triangle Park, NC, September 1988.
19. G. E. Muleski, et al., Extended Evaluation Of Unpaved Road Dust Suppressants In The Iron And
Steel Industry, EPA-600/2-84-027, U. S. Environmental Protection Agency, Cincinnati, OH,
February 1984.
20. C. Cowherd, Jr., and J. S. Kinsey, Identification, Assessment And Control Of Fugitive Paniculate
Emissions, EPA-600/8-86-023, U. S. Environmental Protection Agency, Cincinnati, OH, August
1986.
21. G. E. Muleski and C. Cowherd, Jr., Evaluation Of The Effectiveness Of Chemical Dust
Suppressants On Unpaved Roads, EPA-600/2-87-102, U. S. Environmental Protection Agency,
Cincinnati, OH, November 1986.
22. Fugitive Dust Background Document And Technical Information Document For Best Available
Control Measures, EPA-450/2-92-004, Office Of Air Quality Planning And Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, September 1992.
9/98 Miscellaneous Sources 13.2.2-15
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