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9.2.2 Pesticide Application
9.2.2.1 General1'2
Pesticides are substances or mixtures used to control plant and animal life for the purposes of
increasing and improving agricultural production, protecting public health from pest-borne disease and
discomfort, reducing property damage caused by pests, and improving the aesthetic quality of outdoor
or indoor surroundings. Pesticides are used widely in agriculture, by homeowners, by industry, and
by government agencies. The largest usage of chemicals with pesticidal activity, by weight of "active
ingredient" (AI), is in agriculture. Agricultural pesticides are used for cost-effective control of
weeds, insects, mites, fungi, nematodes, and other threats to the yield, quality, or safety of food.
The annual U. S. usage of pesticide AIs (i. e., insecticides, herbicides, and fungicides) is over
800 million pounds.
Air emissions from pesticide use arise because of the volatile nature of many AIs, solvents,
and other additives used in formulations, and of the dusty nature of some formulations. Most modern
pesticides are organic compounds. Emissions can result directly during application or as the AI or
solvent volatilizes over time from soil and vegetation. This discussion will focus on emission factors
for volatilization. There are insufficient data available on paniculate emissions to permit emission
factor development.
9.2.2.2 Process Description3"*5
Application Methods -
Pesticide application methods vary according to the target pest and to the crop or other value
to be protected. In some cases, the pesticide is applied directly to the pest, and in others to the host
plant. In still others, it is used on the soil or in an enclosed air space. Pesticide manufacturers have
developed various formulations of AIs to meet both the pest control needs and the preferred
application methods (or available equipment) of users. The types of formulations are dry, liquid, and
aerosol.
Dry formulations can be dusts, granules, wettable and soluble powders, water dispersible
granules, or baits. Dusts contain small particles and are subject to wind drift. Dusts also may
present an efficacy problem if they do not remain on the target plant surfaces. Granular formulations
are larger, from about 100 to 2,500 micrometers (jan), and are usually intended for soil application.
Wettable powders and water-dispersible granules both form suspensions when mixed with water
before application. Baits, which are about the same size as granules, contain the AI mixed with a
food source for the target pest (e. g., bran or sawdust).
Liquid formulations may be solutions, emulsions (emulsifiable concentrates), aerosols, or
fumigants. In a liquid solution, the AI is solubilized hi either water or organic solvent. True
solutions are formed when miscible liquids or soluble powders are dissolved in either water or
organic liquids. Emulsifiable concentrates are made up of the AI, an organic solvent, and an
emulsifier, which permits the pesticide to be mixed with water in the field. A flowable formulation
contains an AI that is not amenable to the formation of a solution. Therefore, the AI is mixed with a
liquid petroleum base and emulsifiers to make a creamy or powdery suspension that can be readily
field-mixed with water.
1/95 Food And Agricultural Industries 9.2.2-1
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Aerosols, which are liquids with an AI in solution with a solvent and a propellant, are used
for fog or mist applications. The ranges of optimum droplet size, by target, are 10 to 50 /*m for
flying insects, 30 to 50 /tm for foliage insects, 40 to 100 jim for foliage, and 250 to 500 /xm for soil
with drift avoidance.
Herbicides are usually applied as granules to the surface of the soil or are incorporated into
the soil for field crops, but are applied directly to plant foliage to control brush and noxious weeds.
Dusts or fine aerosols are often used for insecticides but not for herbicides. Fumigant use is limited
to confined spaces. Some fumigants are soil-injected, and then sealed below the soil surface with a
plastic sheeting cover to minimize vapor loss.
Several types of pesticide application equipment are used, including liquid pumps (manual and
power operated), liquid atomizers (hydraulic energy, gaseous energy, and centrifugal energy), dry
application, and soil application (liquid injection application).
9.2.2.3 Emissions And Controls1'7"14
Organic compounds and paniculate matter are the principal air emissions from pesticide
application. The active ingredients of most types of synthetic pesticides used hi agriculture have some
degree of volatility. Most are considered to be essentially nonvolatile or semivolatile organic
compounds (SVOC) for analytical purposes, but a few are volatile (e. g., fumigants). Many widely
used pesticide formulations are liquids and emulsifiable concentrates, which contain volatile organic
solvents (e. g., xylene), emulsifiers, diluents, and other organics. In this discussion, all organics
other than the AI that are liquid under ambient conditions, are considered to have the potential to
volatilize from the formulation. Paniculate matter emissions with adsorbed active ingredients can
occur during application of dusts used as pesticide carriers, or from subsequent wind erosion.
Emissions also may contain pesticide degradation products, which may or may not be volatile. Most
pesticides, however, are sufficiently long lived to allow some volatilization before degradation occurs.
Processes affecting emissions through volatilization of agricultural pesticides applied to soils
or plants have been studied in numerous laboratory and field research investigations. The 3 major
parameters that influence the rate of volatilization are the nature of the AI, the meteorological
conditions, and soil adsorption.
Of these 3 major parameters, the nature of the AI probably has the greatest effect. The
nature of the AI encompasses physical properties, such as vapor pressure, Henry's law constant, and
water solubility; and chemical properties, including soil particle adsorption and hydrolysis or other
degradative mechanisms. At a given temperature, every AI has a characteristic Henry's law constant
and vapor pressure. The evaporation rate of an AI is determined hi large part by its vapor pressure,
and the vapor pressure increases with temperature and decreases with adsorption of the AI to soil.
The extent of volatilization depends hi part on air and soil temperature. Temperature has a different
effect on each component relative to its vapor pressure. An increase hi temperature can increase or
decrease volatilization because of its influence on other factors such as diffusion of the AI toward or
away from the soil surface, and movement of the water in the soil. Usually, an increase hi
temperature enhances volatilization because the vapor pressure of the AI increases. Wind conditions
also can affect the rate of AI volatilization. Increased wind and turbulence decrease the stagnant
layers above a soil surface and increase the mixing of air components near the surface, thus
increasing volatilization. The effects of the third major parameter, soil adsorption, depend not only
on the chemical reactivity of the AI but to a great extent on the characteristics of the soil. Increased
amounts of organic matter or clay hi soils can increase adsorption and decrease the volatilization rate
of many AIs, particularly the more volatile AIs that are nonionic, weakly polar molecules. The soil
9.2.2-2 EMISSION FACTORS 1/95
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moisture content can also influence the rate of vaporization of the weakly polar AIs. When soil is
very dry, the volatility of the AI is lowered significantly, resulting in a decrease in emissions. The
presence of water in the soil can accelerate the evaporation of pesticides because, as water evaporates
from the soil surface, the AI present in the soil will be transported to the surface, either in solution or
by codistillation or convection effects. This action is called the "wick effect" because the soil acts as
a wick for movement of the AI.
Many materials used as inert ingredients in pesticide formulations are organic compounds that
are volatile liquids or gases at ambient conditions. All of these compounds are considered to be
volatile organic compounds (VOC). During the application of the pesticides and for a subsequent
period of time, these organic compounds are volatilized into the atmosphere. Most of the liquid inert
ingredients in agriculture pesticide formulations have higher vapor pressures than the AIs. However,
not all inert ingredients are VOCs. Some liquid formulations may contain water, and solid
formulations typically contain nonvolatile (solid) inert ingredients. Solid formulations contain small
quantities of liquid organic compounds in their matrix. These compounds are often incorporated as
carriers, stabilizers, surfactants, or emulsifiers, and after field application are susceptible to
volatilization from the formulation. The VOC inert ingredients are the major contributors to
emissions that occur within 30 days after application. It is assumed that 100 percent of these VOC
inert ingredients volatilize within that time.
Two important mechanisms that increase emissions are diffusion and volatilization from plant
surfaces. Pesticides in the soil diffuse upward to the surface as the pesticide at the soil surface
volatilizes. A pesticide concentration gradient is thus formed between the depleted surface and the
more concentrated subsurface. Temperature, pesticide concentration, and soil composition influence
the rate of diffusion. The rate of volatilization from plant surfaces depends on the manner in which
the pesticide covers the plant structure. Higher volatilization losses can occur from plant surfaces
when the pesticide is present as droplets on the surface. Volatilization slows when the remaining
pesticide is either left in the regions of the plant structure less exposed to air circulation or is
adsorbed onto the plant material.
Alternative techniques for pesticide application or usage are not widely used, and those that
are used are often intended to increase cost effectiveness. These techniques include (1) use of
application equipment that increases the ratio of amount of pesticide on target plants or soil to that
applied; (2) application using soil incorporation; (3) increased usage of water-soluble pesticides in
place of solvent-based pesticides; (4) reformulation of pesticides to reduce volatility; and (5) use of
integrated pest management (IPM) techniques to reduce the amount of pesticide needed.
Microencapsulation is another technique in which the active ingredient is contained in various
materials that slowly degrade to allow for timed release of pesticides.
9.2.2.4 Emission Factors1'15'21
The variety in pesticide AIs, formulations, application methods, and field conditions, and the
limited data base on these aspects combine to preclude the development of single-value emission
factors. Modeling approaches have been, therefore, adopted to derive emission factors from readily
available data, and algorithms have been developed to calculate emissions for surface application and
soil incorporation from product-specific data, supplemented, as necessary, by default values.
Emission factors for pesticide AIs, derived through modeling approaches, are given in Table 9.2.2-4.
Factors are expressed in units of kilograms per megagram (kg/Mg) and pounds per ton (Ib/ton). No
emission factors are estimated beyond 30 days because after that time degradation processes (e. g.,
hydrolysis or microbial degradation) and surface runoff can have major effects on the loss of AIs, and
volatilization after that time may not be the primary loss mechanism. The emission factors calculated
1/95 Food And Agricultural Industries 9.2.2-3
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using the model are rated "E" because the estimates are derived from mathematical equations using
physical properties of the AIs. Because the factors were developed from a very limited data base,
resulting emission estimates should be considered approximations. As additional data become
available, the algorithm and emission factors will be revised, when appropriate, to incorporate the
new data.
This modeling approach estimates emissions from volatilized organic material. No emission
estimates were developed for paniculate because the available data were inadequate to establish
reliable emission factors. The modeled emission factors also address only surface-applied and
soil-incorporated pesticides. In aerial application, drift effects predominate over volatilization, and
insufficient data are currently available to develop emission factors for this application method.
The model covers the 2 key types of volatilization emissions, (1) those of active (pesticidal)
ingredients, and (2) those VOC constituents of the inert (nonpesticidal) ingredients. For some
formulations (e. g., liquids and emulsifiable concentrates), emissions of inert VOCs may be an order
of magnitude or more higher than those of the AIs, but for other formulations (e. g., granules) the
VOC emissions are either relatively less important or unimportant. Thus, both parts of the model are
essential, and both depend on the fact that volatilization rates depend in large measure on the vapor
pressure of specific ingredients, whether AIs or inerts. Use of the model, therefore, requires the
collection of certain information for each pesticide application.
Both the nature of the pesticide and the method by which it is applied must either be known
or estimated. Pesticide formulations contain both an AI and inert ingredients, and the pesticide
volatilization algorithm is used to estimate their emissions separately. Ideally, the information
available for the algorithm calculation will match closely the actual conditions. The following
information is necessary to use the algorithm.
- Total quantity of formulation applied;
- Method by which the formulation was applied (the algorithm cannot be used for aerially
applied pesticide formulations);
- Name of the specific AI(s) in the formulation;
- Vapor pressure of the AI(s);
- Type of formulation (e. g., emulsifiable concentrate, granules, microcapsules, powder);
- Percentage of inert ingredients; and
- Quantity or percentage of VOC in the inerts.
9.2.2.5 UseOf The Algorithm1'18'20
The algorithm for estimating volatilization emissions is applied in a 6-step procedure, as
follows:
1. Determine both the application method and the quantity of pesticide product applied.
2. Determine the type of formulation used.
3. Determine the specific AI(s) in the formulation and its vapor pressure(s).
4. Determine the percentage of the AI (or each AI) present.
9.2.2-4 EMISSION FACTORS 1/95
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5. Determine the VOC content of the formulation.
6. Perform calculations of emissions.
Information for these steps can be found as follows:
- Item 1 — The quantity can be found either directly from the weight purchased or used for
a given application or, alternately, by multiplying the application rate (e. g., kg/acre)
times the number of units (acres) treated. The algorithm cannot be used for aerial
application.
- Items 2, 3, and 4 — This information is presented on the labels of all pesticide containers.
Alternatively, it can be obtained from either the manufacturer, end-use formulator, or
local distributor. Table 9.2.2-1 provides vapor pressure data for selected AIs. If the
trade name of the pesticide and the type of formulation are known, the specific AI in the
formulation can be obtained from Reference 2 or similar sources. Table 9.2.2-2 presents
the specific AIs found in several common trade name formulations. Assistance in
determining the various formulations for specific AIs applied may be available from the
National Agricultural Statistics Service, U. S. Department Of Agriculture, Washington,
DC.
- Item 5 — The percent VOC content of the inert ingredient portion of the formulation can
be requested from either the manufacturer or end-use formulator. Alternatively, the
estimated average VOC content of the inert portions of several common types of
formulations is given in Table 9.2.2-3.
- Item 6 — Emissions estimates are calculated separately for the AI using Table 9.2.2-4,
and for the VOC inert ingredients as described below and illustrated in the example
calculation.
Emissions Of Active Ingredients -
First, the total quantity of AI applied to the crop is calculated by multiplying the percent
content of the AI in the formulation by the total quantity of applied formulation. Second, the vapor
pressure of the specific AI(s) at 20 to 25°C is determined from Table 9.2.2-1, Reference 20, or other
sources. Third, the vapor pressure range that corresponds to the vapor pressure of the specific AI is
found in Table 9.2.2-4. Then the emission factor for the AI(s) is calculated. Finally, the total
quantity of applied AI(s) is multiplied by the emission factor(s) to determine the total quantity of AI
emissions within 30 days after application. Table 9.2.2-4 is not applicable to emissions from
fumigant usage, because these gaseous or liquid products are highly volatile and would be rapidly
discharged to the atmosphere.
Emissions Of VOC Inert Ingredients -
The total quantity of emissions because of VOCs in the inert ingredient portion of the
formulation can be obtained by using the percent of the inert portion contained in the formulated
product, the percent of the VOCs contained in the inert portion, and the total quantity of formulation
applied to the crop. First, multiply the percentage of inerts in the formulation by the total quantity of
applied formulation to obtain the total quantity of inert ingredients applied. Second, multiply the
percentage of VOCs in the inert portion by the total quantity of inert ingredient applied to obtain the
total quantity of VOC inert ingredients. If the VOC content is not known, use a default value from
Table 9.2.2-3 appropriate to the formulation. Emissions of VOC inert ingredients are assumed to be
100 percent by 30 days after application.
1/95 Food And Agricultural Industries 9.2.2-5
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Total Emissions -
Add the total quantity of VOC inert ingredients volatilized to the total quantity of emissions
from the AI. The sum of these quantities represents the total emissions from the application of the
pesticide formulation within 30 days after application.
Example Calculation -
3,629 kg, or 8,000 Ib, of Spectracide® have been surface applied to cropland, and an estimate
is desired of the total quantity of emissions within 30 days after application.
1. The active ingredient in Spectracide* is diazinon (Reference 2, or Table 9.2.2-2). The
pesticide container states that the formulation is an emulsifiable concentrate containing
58 percent active ingredient and 42 percent inert ingredient.
2. Total quantity of AI applied:
0.58 * 3,629 kg = 2,105 kg (4,640 Ib) of diazinon applied
= 2.105 Mg
2.105 Mg * 1.1 ton/Mg = 2.32 tons of diazinon applied
From Table 9.2.2-1, the vapor pressure of diazinon is 6 x 10"5 millimeters (mm) mercury at
about 25°C. From Table 9.2.2-4, the emission factor for AIs with vapor pressures between 1 x 10"6
and 1 x 10"4 during a 30-day interval after application is 350 kg/Mg (700 Ib/ton) applied. This
corresponds to a total quantity of diazinon volatilized of 737 kg (1,624 Ib) over the 30-day interval.
3. From the pesticide container label, it is determined that the inert ingredient content of the
formulation is 42 percent and, from Table 9.2.2.3, it can be determined that the average
VOC content of the inert portion of emulsifiable concentrates is 56 percent.
Total quantity of emissions from inert ingredients:
0.42 * 3,629 kg * 0.56 = 854 kg (1,882 Ib) of VOC inert ingredients
One hundred percent of the VOC inert ingredients is assumed to volatilize within 30 days.
4. The total quantity of emissions during this 30-day interval is the sum of the emissions
from inert ingredients and from the AI. In this example, the emissions are 854 kg
(1,882 Ib) of VOC plus 737 kg (1,624 Ib) of AI, or 1,591 kg (3,506 Ib).
9.2.2-6 EMISSION FACTORS 1/95
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Table 9.2.2-1. VAPOR PRESSURES OF SELECTED ACTIVE INGREDIENTS*
Active Ingredient
Vapor Pressure
(mm Hg at 20 to 25°C)
1,3-Dichloropropene
2,4-D acid
Acephate
Alachlor
Aldicarb
Aldoxycarb
Amitraz
Amitrole (aminotriazole)
Atrazine
Azinphos-methyl
Benefin (benfluralin)
Benomyl
Bifenox
Bromacil acid
Bromoxynil butyrate ester
Butylate
Captan
Carbaryl
Carbofuran
Chlorobenzilate
Chloroneb
Chloropicrin
Chlorothalonil
Chlorpyrifos
Clomazone (dimethazone)
Cyanazine
Cyromazine
DCNA (dicloran)
DCPA (chlorthal-dimethyl; Dacthal*)
Diazinon
Dichlobenil
Dicofol
Dicrotofos
Dimethoate
Dinocap
29
8.0 x 10-6
1.7 x 10-6
1.4x 10'5
3.0 x 10'5
9 x 10'5
2.6 x 10^
4.4 x 10'7
2.9 x ID'7
2.0 x 10-7
6.6 x 10'5
< 1.0 x lO"10
2.4 x 10-6
S.lxlO'7
l.OxlO-4
1.3 x 10-2
8.0 x lO'8
1.2 x ID"6
6.0 x 10-7
6.8 x 10-6
3.0 x 10-3
18
1.0 x 10'3 (estimated)
1.7 x 10'5
1.4 x 10-4
1.6 x 10-9
3.4 x 10-9
1.3 x 10-6
2.5 x 10-*
6.0 x 10'5
1.0 x 10'3
4.0 x 10'7
1.6x 10^
2.5 x 10-5
4.0 x 10-*
1/95
Food And Agricultural Industries
9.2.2-7
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Table 9.2.2-1 (cont.).
Active Ingredient
Vapor Pressure
(mm Hg at 20 to 25°C)
Disulfoton
Diuron
Endosulfan
EPTC
Ethalfluralin
Ethion
Ethoprop (ethoprophos)
Fenamiphos
Fenthion
Fluometuron
Fonofos
Isofenphos
Lindane
Linuron
Malathion
Methamidophos
Methazole
Methiocarb (mercaptodimethur)
Methomyl
Methyl parathion
Metolachlor
Metribuzin
Mevinphos
Molinate
Naled
Norflurazon
Oxamyl
Oxyfluorfen
Parathion (ethyl parathion)
PCNB
Pendimethalin
Permethrin
Phorate
Phosmet
Profenofos
1.5 x
6.9 x ID'8
1.7 x 10'7
3.4 x 10'2
8.8 x 1(T5
2.4 x KT6
3.8 x 10-4
l.Ox ID"6
2.8 x 1Q-6
9.4 x 10'7
3.4 x 10^
3.0 x 10-6
3.3 x 1Q-5
1.7x 10'5
8.0 x 10-6
8.0 x 10-4
l.OxlO-6
1.2 x 10^
5.0 x 10-5
l.SxlO'5
3.1 x lO'5
< 1.0 x 1Q-5
1.3 x 10-4
5.6 x lO'3
2.0 x 10-4
2.0 x 10'8
2.3 x 10^
2.0 x 10'7
5.0 x 10-6
1.1 x 1Q-4
9.4 x lO"6
1.3 x 10'8
6.4 x 10-4
4.9 x 10-7
9.0 x 10-7
9.2.2-8
EMISSION FACTORS
1/95
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Table 9.2.2-1 (cont.).
Active Ingredient
Prometon
Prometryn
Propachlor
Propanil
Propargite
Propazine
Propoxur
Siduron
Simazine
Tebuthiuron
Terbacil
Terbufos
Thiobencarb
Thiodicarb
Toxaphene
Triallate
Tribufos
Trichlorfon
Trifluralin
Triforine
Vapor Pressure
(mm Hg at 20 to 25 °C)
7.7 x 10^
1.2 x 1Q-6
2.3 x 10^
4.0 x 10"5
3.0 x 10-3
1.3 x 10'7
9.7 x 10"6
4.0 x 10'9
2.2 x 10'8
2.0 x 1Q-6
3.1 x 10'7
3.2 x 1Q-4
2.2 x 10'5
l.Ox 1Q-7
4.0 x 1Q-6
1.1 x 10-4
1.6x 10-6
2.0 x 10-6
1.1 x lO"4
2.0 x 10'7
Reference 20. Vapor pressures of other pesticide active ingredients can also be found there.
Table 9.2.2-2. TRADE NAMES FOR SELECTED ACTIVE INGREDIENTS1
Trade Namesb
Insecticides
AC 8911
Acephate-met
Alkron*
Aileron*
Aphamite®
Bay 17147
Bay 19639
Bay 70143
Active Ingredient0
Phorate
Methamidophos
Ethyl Parathion
Ethyl Parathion
Ethyl Parathion
Azinphos-methyl
Disulfoton
Carbofuran
1/95
Food And Agricultural Industries
9.2.2-9
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Table 9.2.2-2 (cont.).
Trade Namesb
Bay 71628
Benzoepin
Beosit®
Brodan*
BugMaster®
BW-21-Z
Carbamine*
Carfene®
Cekubaryl®
Cekudifol®
Cekuthoate®
CGA-15324
Chlorpyrifos 99%
Chlorthiepin®
Comite®
Corothion®
Crisulfan®
Crunch*
Curacron
Curaterr®
Cyclodan®
Cygon 400*
D1221
Daphene®
Dazzel*
Denapon®
Devicarb*
Devigon®
Devisulphan®
Devithion*
Diagran®
Dianon®
Diaterr-Fos®
Diazajet®
Diazatol®
Diazide®
Dicarbam*
Active Ingredient0
Methamidophos
Endosulfan
Endosulfan
Chlorpyrifos
Carbaryl
Pennethryn
Carbaryl
Azinphos-methyl
Carbaryl
Dicofol
Dimethoate
Profenofos
Chlorpyrifos
Endosulfan
Propargite
Ethyl Parathion
Endosulfan
Carbaryl
Profenofos
Carbofuran
Endosulfan
Dimethoate
Carbofuran
Dimethoate
Diazinon
Carbaryl
Carbaryl
Dimethoate
Endosulfan
Methyl Parathion
Diazinon
Diazinon
Diazinon
Diazinon
Diazinon
Diazinon
Carbaryl
9.2.2-10
EMISSION FACTORS
1/95
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Table 9.2.2-2 (cont.).
Trade Namesb
Active Ingredient0
Dicomite®
Dimethogen®
Dimet*
Dizinon®
DPX 1410
Dyzol®
E-605
Ectiban®
Endocide®
Endosol®
ENT 27226
ENT27164
Eradex®
Ethoprop
Ethoprophos
Ethylthiodemeton
Etilon®
Fezudin
FMC-5462
FMC-33297
Fonofos
Force®
Fosfamid
Furacarb*
G-24480
Gardentox®
Gearphos®
Golden Leaf Tobacco Spray®
Hexavin®
Hoe 2671
Indothrin*
Insectophene*
Insyst-D®
Karbaspray*
Kayazinon®
Kayazol®
Kryocide®
Dicofol
Dimethoate
Dimethoate
Diazinon
Oxamyl
Diazinon
Ethyl Parathion
Permethryn
Endosulfan
Endosulfan
Propargite
Carbofuran
Chlorpyrifos
Ethoprop
Ethoprop
Disulfoton
Ethyl Parathion
Diazinon
Endosulfan
Permethryn
Dyfonate
Tefluthrin
Dimethoate
Carbofuran
Diazinon
Diazinon
Methyl Parathion
Endosulfan
Carbaryl
Endosulfan
Permethryn
Endosulfan
Disulfoton
Carbaryl
Diazinon
Diazinon
Cryolite
1/95
Food And Agricultural Industries
9.2.2-11
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Table 9.2.2-2 (cont.).
Trade Namesb
Lannate® LV
Larvin®
Metafos
Metaphos®
Methomex®
Methyl
Metiltriazotion
Nipsan®
Niran®
Nivral®
NRDC 143
Ortho 124120
Orthophos®
Panihion®
Paramar®
Paraphos*
Parathene®
Parathion
Parathion
Parawet*
Partron M®
Penncap-M®
PhoskU®
Piridane®
Polycron®
PP557
Pramex®
Prokil®
PT265®
Qamlin*
Rampart®
Rhodiatox®
S276
SD 8530
Septene®
Sevin 5 Pellets®
Soprathion®
Active Ingredient0
Methomyl
Thiodicarb
Methyl Parathion
Methyl Parathion
Methomyl
Methyl Parathion
Azinphos-methyl
Diazinon
Ethyl Parathion
Thiodicarb
Permethryn
Acephate
Ethyl Parathion
Ethyl Parathion
Ethyl Parathion
Ethyl Parathion
Ethyl Parathion
Methyl Parathion
Ethyl Parathion
Ethyl Parathion
Methyl Parathion
Methyl Parathion
Ethyl Parathion
Chlorpyrifos
Profenofos
Permethryn
Permethryn
Cryolite
Diazinon
Pennethryn
Phorate
Ethyl Parathion
Disulfoton
Trimethacarb
Carbaryl
Carbaryl
Ethyl Parathion
9.2.2-12
EMISSION FACTORS
1/95
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Table 9.2.2-2 (oont.).
Trade Namesb
Spectracide®
SRA 5172
Stathion®
Tekwaisa®
Temik*
Tercyl*
Thimul*
Thiodan
Thiofor*
Thiophos
Tricarnam*
Trimetion®
UC 51762
UC 27867
Uniroyal D014
Yaltox®
None listed
None listed
Herbicides
A-4D
AC 92553
Acclaim
Acme MCPA Amine 4®
Aljaden®
Amiben®
Amilon®-WP
Amine*
Aqua-Kleen®
Arrhenal®
Arsinyl*
Assure*
Avadex® BW
Banlene Plus®
Banvel®
Barrage®
Basagran
Bay 30130
Active Ingredient0
Diazinon
Methamidophos
Ethyl Parathion
Methyl Parathion
Aldicarb
Carbaryl
Endosulfan
Endosulfan
Endosulfan
Ethyl Parathion
Carbaryl
Dimethoate
Thiodicarb
Trimethacarb
Propargite
Carbofuran
Dicrotophos
Terbufos
2,4-D
Pendimethalin
Fenoxaprop-ethyl
MCPA
Sethoxydim
Chloramben
Chloramben
MCPA
2,4-D
DSMA
DSMA
Quizalofop-ethyl
Triallate
MCPA
Dicamba
2,4-D
Bentazon
Propanil
1/95
Food And Agricultural Industries
9.2.2-13
-------
Tabla 9.2.2-2 (cont.).
Trade Namesb
Bay DIG 1468
Bay 94337
Benefex*
Benfluralin
Bentazon
Bethrodine
BH* MCPA
Bioxone*
Blazer*
Bolero*
Border-Master*
Brominex*
C-2059
Cekuiron*
Cekuquat*
Cekusima*
CGA-24705
Checkmate*
Chloroxone*
Classic*
Clomazone
Command*
CP50144
Crisuron®
Croprider*
Dacthal*
Dailon*
Depon*
Dextrone*
Di-Tac*
Diater*
DMA
DMA-100»
DPA
DPX-Y6202
EL-110
EL-161
Active Ingredient*5
Metribuzin
Metribuzin
Benefin
Benefin
Bentazon
Benefin
MCPA
Methazole
Aciflurofen
Thiobencarb
MCPA
Bromoxynil
Fluometuron
Diuron
Paraquat
Simazine
Metolachlor
Sethoxydim
2,4-D
Chlorimuron-ethyl
Clomazone
Clomazone
Alachlor
Diuron
2,4-D
DCPA
Diuron
Fenoxaprop-ethyl
Paraquat
DSMA
Diuron
DSMA
DSMA
Propanil
Quizalofop-ethyl
Benefin
Ethalfluralin
9.2.2-14
EMISSION FACTORS
1/95
-------
Table 9.2.2-2 (cont.).
Trade Namesb
Active Ingredient0
Emulsamine*
Esgram*
Excel*
EXP-3864
Expand*
Far-Go*
Farmco Diuron*
Fannco Atrazine Gesaprim*
Fervinal*
Ferxone*
Furore*
Fusilade 2000
G-30027
G-34161
G-34162
Gamit*
Genate Plus*
Glyphosate Isopropylamine Salt
Goldquat* 276
Grasidim*
HerbAll*
Herbaxon*
Herbixol*
Higalcoton*
Hoe 002810
Hoe-023408
Hoe-Grass*
Hoelon*
Illoxan*
Kilsem*
Lasso*
Lazo*
Legumex Extra*
Lexone* 4L
Lexone* DF*
Linorox*
LS 801213
2,4-D
Paraquat
Fenoxaprop-ethyl
Quizalofop-ethyl
Sethoxydim
Triallate
Diuron
Atrazine
Sethoxydim
2,4-D
Fenoxaprop-ethyl
Fluazifop-p-butyl
Atrazine
Prometryn
Ametryn
Clomazone
Butylate
Glyphosate
Paraquat
Sethoxydim
MSMA
Paraquat
Diuron
Fluometuron
Linuron
Diclofop-methyl
Diclofop-methyl
Diclofop-methyl
Diclofop-methyl
MCPA
Alachlor
Alachlor
MCPA
Metribuzin
Metribuzin
Linuron
Aciflurofen
1/95
Food And Agricultural Industries
9.2.2-15
-------
Table 9.2.2-2 (cont).
Trade Namesb
M.T.F.*
Magister*
Mephanac*
Merge 823*
Methar*30
Mezopur*
Monosodium methane arsenate
Nabu*
Option*
Oxydiazol
Paxilon® ,
Pillarquat*
Pillarxone*
Pillarzo*
Pilot*
Plantgard®
Pledge*
PP005
Primatol Q*
Probe
Prop-Job*
Propachlor
Prowl*
Rattler*
RH-6201
Rodeo*
Roundup*
S 10145
Sarclex*
Saturno®
Saturn*
Scepter*
SD 15418
Sencor* 4
Sencor* DF
Shamrox*
Sodar*
Active Ingredient0
Trifluralin
Clomazone
MCPA
MSMA
DSMA
Metbazole
MSMA
Sethoxydim
Fenoxaprop-ethyl
Methazole
Methazole
Paraquat
Paraquat
Alachlor
Quizalofop-ethyl
2,4-D
Bentazon
Fluazifop-p-butyl
Prometryn
Methazole
Propanil
Propachlor
Pendimethalin
Glyphosate
Aciflurofen
Glyphosate
Glyphosate
Propanil
Linuron
Thiobencarb
Thiobencarb
Imazaquin
Cyanazine
Metribuzin
Metribuzin
MCPA
DSMA
9.2.2-16
EMISSION FACTORS
1/95
-------
Table 9.2.2-2 (cont).
Trade Namesb
Sonalan*
Squadron*
Squadron*
Strel*
Surpass*
Targa*
Target MSMA*
Telok*
Tigrex*
Total*
Toxer*
Trans-Vert*
Tri^*
Tri-Scept*
Tributon*
Trifluralina 600*
Trinatox D*
Tritex-Extra®
Tunic*
Unidron*
VCS 438
Vegiben*
Vernam 10G
Vernam 7E
Vonduron*
Weed-Rhap*
Weed-B-Gon*
Weedatul*
Weedtrine-n*
Whip*
WL 19805
Zeaphos*
Zelan*
None listed
None listed
None listed
None listed
Active Ingredient0
Ethalfluralin
Imazaquin
Pendimethalin
Propanil
Vernolate
Quizalofop-ethyl
MSMA
Norflurazon
Diuron
Paraquat
Paraquat
MSMA
Trifluralin
Imazaquin
2,4-D
Trifluralin
Ametryn
Sethoxydim
Methazole
Diuron
Methazole
Chloramben
Vernolate
Vernolate
Diuron
MCPA
2,4-D
2,4-D
2,4-D
Fenoxaprop-ethyl
Cyanazine
Atrazine
MCPA
EPTC
Fomesafen
Molinate
Tridiphane
1/95
Food And Agricultural Industries
9.2.2-17
-------
Table 9.2.2-2 (cont.).
Trade Namesb
Active Ingredient0
Other Active Ingredients
A7 Vapam*
Aquacide®
Avicol®
Carbarn (MAP)
Clortocaf Ramato®
Clortosip®
Cotton Aide HC®
De-Green*
DBF*
Deiquat
Dextrone®
E-Z-OffD®
Earthcide®
Exotherm Termil*
Folex®
Folosan®
Fos-Fall A®
Karbation®
Kobutol®
Kobu®
Kypman® 80
M-Diphar®
Mancozin®
Maneba®
Manebe
Manzate® 200
Manzeb
Manzin*
Maposol*
Metam for the Acid
Moncide*
Montar®
Nemispor®
Pentagon®
Quintozene
Rad-E-Cate* 25
Metam Sodium
Diquat
PCNB
Metam Sodium
Chlorothalonil
Chlorothalonil
Cacodylic
Tribufos
Tribufos
Diquat
piquat
Tribufos
PCNB
Chlorothalonil
Tribufos
PCNB
Tribufos
Metam Sodium
PCNB
PCNB
Maneb
Maneb
Mancozeb
Maneb
Maneb
Mancozeb
Mancozeb
Mancozeb
Metam Sodium
Metam Sodium
Cacodylic
Cacodylic
Mancozeb
PCNB
PCNB
Cacodylic
9.2.2-18
EMISSION FACTORS
1/95
-------
Table 9.2.2-2 (cont).
Trade Namesb
Active Ingredient0
Region
Riozeb®
RTU* PCNB
Sectagon* n
SMDC
Soil-Prep*
Sopranebe*
Superman* Maneb F
Terrazan*
Tersan 1991*
TriPCNB*
Tubotbane*
Weedtrine-D*
Ziman-Dithane®
None listed
None listed
None listed
Diquat
Mancozeb
PCNB
Metam Sodium
Metam Sodium
Metam Sodium
Maneb
Maneb
PCNB
Benomyl
PCNB
Maneb
Diquat
Mancozeb
Dimethipin
Ethephon
Thiadiazuron
a Reference 2. See Reference 22 for selected pesticides used on major field crops.
b Reference 2.
c Common names. See Reference 2 for chemical names.
Table 9.2.2-3. AVERAGE VOC CONTENT OF PESTICIDE INERT INGREDIENT
PORTION, BY FORMULATION TYPE*
Formulation Type
Average VOC Content Of Inert Position
(wt. %)
Oils
Solution/liquid (ready to use)
Emulsifiable concentrate
Aqueous concentrate
Gel, paste, cream
Pressurized gas
Flowable (aqueous) concentrate
Microencapsulated
Pressurized liquid/sprays/foggers
Soluble powder
Impregnated material
66
20
56
21
40
29
21
23
39
12
38
1/95
Food And Agricultural Industries
9.2.2-19
-------
Table 9.2.2-3 (cont.).
Formulation Type
Average VOC Content Of Inert Position
(wt. %)
Pellet/tablet/cake/briquette
Wettable powder
Dust/powder
Dry flowable
Granule/flake
Suspension
Paint/coatings
27
25
21
28
25
15
64
a Reference 21.
Table 9.2.2-4 (Metric And English Units).
UNCONTROLLED EMISSION FACTORS FOR PESTICIDE ACTIVE INGREDIENTS4
EMISSION FACTOR RATING: E
Vapor Pressure Range
(mm Hg at 20 to 25°C)b
Surface application
(SCC 24-61-800-001)
1 x 10-4 to 1 x 10-6
> 1 x 1Q-4
Soil incorporation
(SCC 24-61-800-002)
< 1 x KT6
1 x 10^ to 1 x 10-6
> 1 x 10-4
Emission Factor0
kg/Mg
350
580
2.7
21
52
Ib/ton
700
1,160
5.4
42
104
a Factors are functions of application method and vapor pressure. SCC = Source Classification
Code.
b See Reference 20 for vapor pressures of specific active ingredients.
c References 1,15-18. Expressed as equivalent weight of active ingredients volatilized/unit weight of
active ingredients applied.
References For Section 9.2.2
1. Emission Factor Documentation For AP-42 Section 9.2.2, Pesticide Application, EPA
Contract No. 68-D2-0159, Midwest Research Institute, Kansas City, MO, September 1994.
2. Farm Chemicals Handbook -1992, Meister Publishing Company, Willoughby, OH, 1992.
9.2.2-20
EMISSION FACTORS
1/95
-------
4. L. E. Bode, et al., eds., Pesticide Formulations And Applications Systems, Volume 10,
American Society For Testing And Materials (ASTM), Philadelphia, PA, 1990.
5. T. S. Colvin and J. H. Turner, Applying Pesticides, 3rd Edition, American Association Of
Vocational Materials, Athens, Georgia, 1988.
6. G. A. Matthews, Pesticide Application Methods, Longham Groups Limited, New York, 1979.
7. D. J. Arnold, "Fate Of Pesticides In Soil: Predictive And Practical Aspects", Environmental
Fate Of Pesticides, Wiley & Sons, New York, 1990.
8. A. W. White, et al., "Trifluralin Losses From A Soybean Field", Journal Of Environmental
Quality, 6(1): 105-110, 1977.
9. D. E. Glotfelty, "Pathways Of Pesticide Dispersion In The Environment", Agricultural
Chemicals Of The Future, Rowman And Allanheld, Totowa, NJ, 1985.
10. J. W. Hamaker, "Diffusion And Volatilization", Organic Chemicals In The Soil Environment,
Dekker, New York, 1972.
11. R. Mayer, et al., "Models For Predicting Volatilization Of Soil-incorporated Pesticides",
Proceedings Of The American Soil Scientists, 35:563-568, 1974.
12. G. S. Hartley, "Evaporation Of Pesticides", Pesticidal Formulations Research Advances In
Chemistry, Series 86, American Chemical Society, Washington, DC, 1969.
13. A. W. Taylor, et al., "Volatilization Of Dieldrin And Heptachlor From A Maize Field",
Journal Of Agricultural Food Chemistry, 24(3):625-631, 1976.
14. A. W. Taylor, "Post-application Volatilization Of Pesticides Under Field Conditions", Journal
Of Air Pollution Control Association, 28(9):922-927, 1978.
15. W. A. Jury, et al., "Use Of Models For Assessing Relative Volatility, Mobility, And
Persistence Of Pesticides And Other Trace Organics In Soil Systems", Hazard Assessment Of
Chemicals: Current Developments, 2:1-43, 1983.
16. W. A. Jury, et al., "Behavior Assessment Model For Trace Organics In Soil: I. Model
Description", Journal Of Environmental Quality, 72(4):558-564, 1983.
17. W. A. Jury, et al., "Behavior Assessment Model For Trace Organics In Soil: EL Chemical
Classification And Parameter Sensitivity", Journal Of Environmental Quality, 73(4):567-572,
1984.
18. W. A. Jury, et al., "Behavior Assessment Model For Trace Organics In Soil: HI. Application
Of Screening Model", Journal Of Environmental Quality, J3(4):573-579, 1984.
19. Alternative Control Technology Document: Control Of VOC Emissions From The Application
Of Agricultural Pesticides, EPA-453/R-92-011, U. S. Environmental Protection Agency,
Research Triangle Park, NC, March 1993.
1/95 Food And Agricultural Industries 9.2.2-21
-------
20. R. D. Wauchope, et al., "The SCS/ARS/CES Pesticide Properties Database For
Environmental Decision-making", Reviews Of Environmental Contamination And Toxicology,
Springer-Verlag, New York, 1992.
21. Written communication from California Environmental Protection Agency, Department Of
Pesticide Regulation, Sacramento, CA, to D. Safriet, U. S. Environmental Protection Agency,
Research Triangle Park, NC, December 6, 1993.
22. Agricultural Chemical Usage: 1991 Field Crops Summary, U.S. Department of Agriculture,
Washington, DC, March 1992.
9.2.2-22 EMISSION FACTORS 1/95
-------
9.23 Orchard Heaters
9.2.3.1 General1-6
Orchard heaters are commonly used in various areas of the United States to prevent frost
damage to fruit and fruit trees. The 5 common types of orchard heaters—pipeline, lazy flame, return
stack, cone, and solid fuel—are shown in Figure 9.2.3-1. The pipeline heater system is operated
from a central control and fuel is distributed by a piping system from a centrally located tank. Lazy
flame, return stack, and cone heaters contain integral fuel reservoirs, but can be converted to a
pipeline system. Solid fuel heaters usually consist only of solid briquettes, which are placed on the
ground and ignited.
The ambient temperature at which orchard heaters are required is determined primarily by the
type of fruit and stage of maturity, by the daytime temperatures, and by the moisture content of the
soil and air.
During a heavy thermal inversion, both convective and radiant heating methods are useful in
preventing frost damage; there is little difference in the effectiveness of the various heaters. The
temperature response for a given fuel rate is about the same for each type of heater as long as the
heater is clean and does not leak. When there is little or no thermal inversion, radiant heat provided
by pipeline, return stack, or cone heaters is the most effective method for preventing damage.
Proper location of the heaters is essential to the uniformity of the radiant heat distributed
among the trees. Heaters are usually located in the center space between 4 trees and are staggered
from 1 row to the next. Extra heaters are used on the borders of the orchard.
9.2.3 Emissions1'6
Emissions from orchard heaters are dependent on the fuel usage rate and the type of heater.
Pipeline heaters have the lowest particulate emission rates of all orchard heaters. Hydrocarbon
emissions are negligible in the pipeline heaters and in lazy flame, return stack, and cone heaters that
have been converted to a pipeline system. Nearly all of the hydrocarbon losses are evaporative losses
from fuel contained in the heater reservoir. Because of the low burning temperatures used, nitrogen
oxide emissions are negligible.
Emission factors for the different types of orchard heaters are presented hi Table 9.2.3-1 and
Figure 9.2.3-2. Factors are expressed in units of kilograms per heater-hour (kg/htr-hr) and pounds
per heater-hour (Ib/htr-hr).
4/73 (Reformatted 1/95) Food And Agricultural Industries 9.2.3-1
-------
PIPELINE HEATER
LAZY FLAME
RETURN STACK
SOLID FUEL
CONE STACK
Figure 9.2.3-1. Types of orchard heaters.6
9.2.3-2
EMISSION FACTORS
(Reformatted 1/95) 4/73
-------
tr.
UJ
=3
•s
cfl
c
r
o\
D
I
4/73 (Reformatted 1/95)
Food And Agricultural Industries
9.2.3-3
-------
Table 9.2.3-1 (Metric And English Units). EMISSION FACTORS FOR ORCHARD HEATERSa
EMISSION FACTOR RATING: C
Pollutant
Particulate
kg/htr-hr
Ib/htr-hr
Sulfur oxides0
kg/htr-hr
Ib/htr-hr
Carbon monoxide
kg/htr-hr
Ib/htr-hr
VOCse
kg/htr-hr
Ib/htr-hr
Nitrogen oxidesf
kg/htr-hr
Ib/htr-hr
Type Of Heater
Pipeline
_b
_b
0.06Sd
0.13S
2.8
6.2
Neg
Neg
Neg
Neg
Lazy Flame
__b
_b
0.05S
0.11S
ND
ND
7.3
16.0
Neg
Neg
Return Stack
__b
_b
0.06S
0.14S
ND
ND
7.3
16.0
Neg
Neg
Cone
_J>
__b
0.06S
0.14S
ND
ND
7.3
16.0
Neg
Neg
Solid Fuel
0.023
0.05
ND
ND
ND
ND
Neg
Neg
Neg
Neg
a References 1,3-4, and 6. ND = no data. Neg = negligible.
b Particulate emissions for pipeline, lazy flame, return stack, and cone heaters are shown in
Figure 9.2.3-2.
c Based on emission factors for fuel oil combustion in Section 1.3.
d S = sulfur content.
e Reference 1. Evaporative losses only. Hydrocarbon emissions from combustion are considered
negligible. Evaporative hydrocarbon losses for units that are part of a pipeline system are
negligible.
f Little nitrogen oxides are formed because of the relatively low combustion temperatures.
References For Section 9.2.3
1. Air Pollution In Ventura County, County Of Ventura Health Department, Santa Paula, CA,
June 1966.
2. Frost Protection In Citrus, Agricultural Extension Service, University Of California, Ventura,
CA, November 1967.
3. Personal communication with Mr. Wesley Snowden, Valentine, Fisher, And Tomlinson,
Consulting Engineers, Seattle, WA, May 1971.
4. Communication with the Smith Energy Company, Los Angeles, CA, January 1968.
5. Communication with Agricultural Extension Service, University Of California, Ventura, CA,
October 1969.
6. Personal communication with Mr. Ted Wakai, Air Pollution Control District, County Of
Ventura, Ojai, CA, May 1972.
9.2.3-4
EMISSION FACTORS
(Reformatted 1/95) 4/73
-------
9.3 Harvesting Operations
9.3.1 Cotton Harvesting
9.3.2 Grain Harvesting
9.3.3 Rice Harvesting
9.3.4 Cane Sugar Harvesting
1/95 Food And Agricultural Industries 9.3-1
-------
9.3.1 Cotton Harvesting
9.3.1.1 General
Wherever it is grown in the U. S., cotton is defoliated or desiccated prior to harvest.
Defoliants are used on the taller varieties of cotton that are machine picked for lint and seed cotton,
and desiccants usually are used on short, stormproof cotton varieties of lower yield that are harvested
by mechanical stripper equipment. More than 99 percent of the national cotton area is harvested
mechanically. The 2 principal harvest methods are machine picking, with 70 percent of the harvest
from 61 percent of the area, and machine stripping, with 29 percent of the harvest from 39 percent of
the area. Picking is practiced throughout the cotton regions of the U. S., and stripping is limited
chiefly to the dry plains of Texas and Oklahoma.
Defoliation may be defined as the process by which leaves are abscised from the plant. The
process may be initiated by drought stress, low temperatures, or disease, or it may be chemically
induced by topically applied defoliant agents or by overfertilization. The process helps lodged plants
to return to an erect position, removes the leaves that can clog the spindles of the picking machine
and stain the fiber, accelerates the opening of mature bolls, and reduces boll rots. Desiccation by
chemicals is the drying or rapid killing of the leaf blades and petioles, with the leaves remaining in a
withered state on the plant. Harvest-aid chemicals are applied to cotton as water-based spray, either
by aircraft or by a ground machine.
Mechanical cotton pickers, as the name implies, pick locks of seed cotton from open cotton
bolls and leave the empty burs and unopened bolls on the plant. Requiring only 1 operator, typical
modern pickers are self-propelled and can simultaneously harvest 2 rows of cotton at a speed of 1.1 to
1.6 meters per second (m/s) (2.5 - 3.6 miles per hour [mph]). When the picker basket gets filled
with seed cotton, the machine is driven to a cotton trailer at the edge of the field. As the basket is
hydraulically raised and tilted, the top swings open allowing the cotton to fall into the trailer. When
the trailer is full, it is pulled from the field, usually by pickup truck, and taken to a cotton gin.
Mechanical cotton strippers remove open and unopened bolls, along with burs, leaves, and
stems from cotton plants, leaving only bare branches. Tractor-mounted, tractor-pulled, or
self-propelled strippers require only 1 operator. They harvest from 1 to 4 rows of cotton at speeds of
1.8 to 2.7 m/s (4.0 - 6.0 mph). After the cotton is stripped, it enters a conveying system that carries
it from the stripping unit to an elevator. Most conveyers utilize either augers or a series of rotating
spike-toothed cylinders to move the cotton, accomplishing some cleaning by moving the cotton over
perforated, slotted, or wire mesh screen. Dry plant material (burs, stems, and leaves) is crushed and
dropped through openings to the ground. Blown air is sometimes used to assist cleaning.
9.3.1.2 Emissions And Controls
Emission factors for the drifting of major chemicals applied to cotton were compiled from
literature and reported in Reference 1. In addition, drift losses from arsenic acid spraying were
developed by field testing. Two off-target collection stations, with 6 air samplers each, were located
downwind from the ground spraying operations. The measured concentration was applied to an
infinite line source atmosphere diffusion model (in reverse) to calculate the drift emission rate. This
was in turn used for the final emission factor calculation. The emissions occur from July to October,
preceding by 2 weeks the period of harvest in each cotton producing region. The drift emission
7/79 (Reformatted 1/95) Food And Agricultural Industries 9.3.1-1
-------
factor for arsenic acid is 8 times lower than previously estimated, since Reference 1 used a ground rig
rather than an airplane, and because of the low volatility of arsenic acid. Various methods of
controlling drop size, proper timing of application, and modification of equipment are practices that
can reduce drift hazards. Fluid additives have been used that increase the viscosity of the spray
formulation, and thus decrease the number of fine droplets (< 100 micrometers [/nn]). Spray nozzle
design and orientation also control the droplet size spectrum. Drift emission factors for the
defoliation or desiccation of cotton are listed hi Table 9.3.1-1. Factors are expressed in units of
grams per kilogram (g/kg) and pounds per ton (Ib/ton).
Table 9.3.1-1 (Metric And English Units). EMISSION FACTORS FOR DEFOLIATION
OR DESICCATION OF COTTON*
EMISSION FACTOR RATING: C
Pollutant
Sodium chlorate
DBF*0
Arsenic acid
Paraquat
Emission Factor1*
g/kg
10.0
10.0
6.1
10.0
Ib/ton
20.0
20.0
12.2
20.0
a Reference 1.
b Factor is in terms of quantity of drift per quantity applied.
c Pesticide trade name.
Three unit operations are involved in mechanical harvesting of cotton: harvesting, trailer
loading (basket dumping), and transport of trailers hi the field. Emissions from these operations are
in the form of solid participates. Paniculate emissions (<7 /on mean aerodynamic diameter) from
these operations were developed hi Reference 2. The particulates are composed mainly of raw cotton
dust and solid dust, which contains free silica. Minor emissions include small quantities of pesticide,
defoliant, and desiccant residues that are present hi the emitted particulates. Dust concentrations from
harvesting were measured by following each harvesting machine through the field at a constant
distance directly downwind from the machine while staying hi the visible plume centerline. The
procedure for trailer loading was the same, but since the trailer is stationary while being loaded, it
was necessary only to stand a fixed distance directly downwind from the trailer while the plume or
puff passed over. Readings were taken upwind of all field activity to get background concentrations.
Paniculate emission factors for the principal types of cotton harvesting operations hi the U. S. are
shown in Table 9.3.1-2. The factors are based on average machine speed of 1.34 m/s (3.0 mph) for
pickers, and 2.25 m/s (5.03 mph) for strippers, on a basket capacity of 109 kg (240 Ib), on a trailer
capacity of 6 baskets, on a lint cotton yield of 63.0 megagrams per square kilometer (Mg/km2)
(1.17 bales/acre) for pickers and 41.2 Mg/km2 (0.77 bale/acre) for strippers, and on a transport speed
of 4.47 m/s (10.0 mph). Factors are expressed hi units of kg/km2 and pounds per square mile
(lb/mi2). Analysis of paniculate samples showed average free silica content of 7.9 percent for
mechanical cotton picking and 2.3 percent for mechanical cotton stripping. Estimated maximum
percentages for pesticides, defoliants, and desiccants from harvesting are also noted in Table 9.3.1-2.
No current cotton harvesting equipment or practices provide for control of emissions. In fact,
9.3.1-2
EMISSION FACTORS
(Reformatted 1/95) 7/79
-------
Table 9.3.1-2 (Metric And English Units). PARTICULATE EMISSION FACTORS*
FOR COTTON HARVESTING OPERATIONS
EMISSION FACTOR RATING: C
Type of Harvester
Picker1"
Two-row, with basket
Stripper0
Two-row, pulled trailer
Two-row, with basket
Four-row, with basket
Weighted average"1
Harvesting
kg/km2
0.46
7.4
2.3
2.3
4.3
lb/mi2
2.6
42
13
13
24
Trailer Loading
kg/km2
0.070
NA
0.092
0.092
0.056
lb/mi2
0.40
NA
0.52
0.52
0.32
Transport
kg/km2
0.43
0.28
0.28
0.28
0.28
lb/mi2
2.5
1.6
1.6
1.6
1.6
Total
kg/km2
0.96
7.7
2.7
2.7
4.6
lb/mi2
5.4
44
15
15
26
a Emission factors are from Reference 2 for paniculate of <7 fim mean aerodynamic diameter.
NA = not applicable.
b Free silica content is 7.9% maximum content of pesticides and defoliants is 0.02%.
c Free silica content is 2.3%; maximum content of pesticides and desiccants is 0.2%.
d The weighted average stripping factors are based on estimates that 2% of all strippers are 4-row
models with baskets and, of the remainder, 40% are 2-row models pulling trailers and 60% are
2-row models with mounted baskets.
equipment design and operating practices tend to maximize emissions. Preharvest treatment
(defoliation and desiccation) and harvest practices are tuned to minimize moisture and trash content,
so they also tend to maximize emissions. Soil dust emissions from field transport can be reduced by
lowering vehicle speed.
References For Section 9.3,1
1. J. A. Peters and T. R. Blackwood, Source Assessment: Defoliation Of Cotton—State Of The
Art, EPA-600/2-77-107g, U. S. Environmental Protection Agency, Cincinnati, OH,
July 1977.
2. J. W. Snyder and T. R. Blackwood, Source Assessment: Mechanical Harvesting Of Cotton—
State Of The Art, EPA-600/2-77-107d, U. S. Environmental Protection Agency, Cincinnati,
OH, July 1977.
7/79 (Reformatted 1/95)
Food And Agricultural Industries
9.3.1-3
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932 Grain Harvesting
9.3.2.1 General1
Harvesting of grain refers to the activities performed to obtain the cereal kernels of the plant
for grain, or the entire plant for forage and/or silage uses. These activities are accomplished by
machines that cut, thresh, screen, clean, bind, pick, and shell the crops in the field. Harvesting also
includes loading harvested crops into trucks and transporting crops in the grain field.
Crops harvested for their cereal kernels are cut as close as possible to the inflorescence (the
flowering portion containing the kernels). This portion is threshed, screened, and cleaned to separate
the kernels. The grain is stored hi the harvest machine while the remainder of the plant is discharged
back onto the field.
Combines perform all of the above activities hi 1 operation. Binder machines only cut the
gram plants and tie them into bundles, or leave them hi a row hi the field (called a windrow). The
bundles are allowed to dry for threshing later by a combine with a pickup attachment.
Corn harvesting requires the only exception to the above procedures. Corn is harvested by
mechanical pickers, picker/shellers, and combines with corn head attachments. These machines cut
and husk the ears from the standing stalk. The sheller unit also removes the kernels from the ear.
After husking, a binder is sometimes used to bundle entire plants into piles (called shocks) to dry.
For forage and/or silage, mowers, crushers, windrowers, field choppers, binders, and similar
cutting machines are used to harvest grasses, stalks, and cereal kernels. These machines cut the
plants as close to the ground as possible and leave them in a windrow. The plants are later picked up
and tied by a baler.
Harvested crops are loaded onto trucks in the field. Grain kernels are loaded through a spout
from the combine, and forage and silage bales are manually or mechanically placed hi the trucks.
The harvested crop is then transported from the field to a storage facility.
9.3.2.2 Emissions And Controls1
Emissions are generated by 3 gram harvesting operations: (1) crop handling by the harvest
machine, (2) loading of the harvested crop into trucks, and (3) transport by trucks hi the field.
Paniculate matter, composed of soil dust and plant tissue fragments (chaff), may be entrained by
wind. Particulate emissions from these operations (<7 micrometers [/im] mean aerodynamic
diameter) were developed in Reference 1. For this study, collection stations with ah* samplers were
located downwind (leeward) from the harvesting operations, and dust concentrations were measured at
the visible plume centerline and at a constant distance behind the combines. For product loading,
since the trailer is stationary while being loaded, it was necessary only to take measurements a fixed
distance downwind from the trailer while the plume or puff passed over. The concentration measured
for harvesting and loading was applied to a point source atmospheric diffusion model to calculate the
source emission rate. For field transport, the air samplers were again placed a fixed distance
downwind from the path of the truck, but this time the concentration measured was applied to a line
source diffusion model. Readings taken upwind of all field activity gave background concentrations.
Particulate emission factors for wheat and sorghum harvesting operations are shown hi Table 9.3.2-1.
2/80 (Reformatted 1/93) Food And Agricultural Industries 9.3.2-1
-------
Table 9.3.2 (Metric And English Units). EMISSION RATES/FACTORS FROM
GRAIN HARVESTING4
EMISSION FACTOR RATING: D
Operation
Harvest machine
Truck loading
Field transport
Emission Rateb
Wheat
mg/s
3.4
1.8
47.0
Ib/hr
0.027
0.014
0.37
Sorghum
mg/s
23.0
1.8
47.0
Ib/hr
0.18
0.014
0.37
Emission Factor0
Wheat
g/km2
170.0
12.0
110.0
lb/mi2
0.96
0.07
0.65
Sorghum
g/km2
1110.0
22.0
200.0
lb/mi2
6.5
0.13
1.2
a Reference 1.
b Assumptions from References 1 are an average combine speed of 3.36 meters per second, combine
swath width of 6.07 meters, and a field transport speed of 4.48 meters per second.
c In addition to footnote b, assumptions are a truck loading time of 6 minutes, a truck capacity of
0.052 km2 for wheat and 0.029 km2 for sorghum, and a filled truck travel time of 125 seconds per
load.
Emission rates are expressed hi units of milligrams per second (mg/s) and pounds per hour (Ib/hr);
factors are expressed hi units of grams per square kilometer (g/km2) and pounds per square mile
(lb/mi2).
There are no control techniques specifically implemented for the reduction of air pollution
emissions from gram harvesting. However, several practices and occurrences do affect emission rates
and concentration. The use of terraces, contouring, and stripcropping to inhibit soil erosion will
suppress the entrainment of harvested crop fragments hi the wind. Shelterbelts, positioned
perpendicular to the prevailing wind, will lower emissions by reducing the wind velocity across the
field. By minimizing tillage and avoiding residue burning, the soil will remain consolidated and less
prone to disturbance from transport activities.
Reference For Section 9.3.2
1. R. A. Wachten and T. R. Blackwood, Source Assessment: Harvesting Of Grain—State Of The
Art, EPA-600/2-79-107f, U. S. Environmental Protection Agency, Cincinnati, OH, July 1977.
9.3.2-2
EMISSION FACTORS
(Refoimatted 1/95) 2/80
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9.3.3 Rice Harvesting
[Work In Progress]
1/95 Food And Agricultural Industries 9.3.3-1
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9.3.4 Cane Sugar Harvesting
[Work In Progress]
1/95 Food And Agricultural Industries 9.3.4-1
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9.4 Livestock And Poultry Feed Operations
9.4.1 Cattle Feedlots
9.4.2 Swine Feedlots
9.4.3 Poultry Houses
9.4.4 Dairy Farms
1/95 Food And Agricultural Industries 9.4-1
-------
9.4.1 Cattle Feedlots
[Work In Progress]
1/95 Food And Agricultural Industries 9.4.1-1
-------
9.4.2 Swine Feedlots
[Work In Progress]
1/95 Food And Agricultural Industries 9.4.2-1
-------
9.43 Poultry Houses
[Work In Progress]
1/95 Food And Agricultural Industries 9.4.3-1
-------
9.4.4 Dairy Farms
[Work In Progress]
1/95 Food And Agricultural Industries 9.4.4-1
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9.5 Animal And Meat Products Preparation
9.5.1 Meat Packing Plants
9.5.2 Meat Smokehouses
9.5.3 Meat Rendering Plants
9.5.4 Manure Processing
9.5.5 Poultry Slaughtering
1/95 Food And Agricultural Industries 9.5-1
-------
9.5.1 Meat Packing Plants
9.5.1.1 General1'2
The meat packing industry is made up of establishments primarily engaged in the slaughtering, for
their own account or on a contract basis for the trade, of cattle, hogs, sheep, lambs, calves, and vealers for
meat to be sold or to be used on the same premises in canning, cooking, curing, and freezing, and in making
sausage, lard, and other products. Also included in this industry are establishments primarily engaged in
slaughtering horses for human consumption.
,3-7
9.5.1.2 Process Description
The following sections describe the operations involved in beef processing, pork processing, and
other meat processing. Figure 9.5.1-1 provides a generic process flow diagram for meat packing operations.
9.5.1.2.1 Beef Processing3'7 -
Animals are delivered from the market or farm to the meat plant and are placed in holding areas.
These holding areas should have adequate facilities for the inspection of livestock, including walkways over
pens, crushes, and other facilities. Sick animals and those unfit for human consumption are identified and
removed from the normal processing flow. Plants should have separate isolation and holding pens for these
animals, and may have separate processing facilities. The live beef animals are weighed prior to processing
so that yield can be accurately determined.
The animals are led from the holding area to the immobilization, or stunning, area where they are
rendered unconscious. Stunning of cattle in the U.S. is usually carried out by means of a penetrating or
nonpenetrating captive bolt pistol. Livestock for Kosher markets are not immobilized prior to
exsanguination.
The anesthetized animals are then shackled and hoisted, hind quarters up, for exsanguination
(sticking), which should be carried out as soon as possible after stunning. In cattle, exsanguination is effected
by severing the carotid artery and the jugular vein. Blood is collected through a special floor drain or
collected in large funneled vats or barrels and sent to a rendering facility for further processing. More
information on rendering operations can be found in AP-42 Section 9.5.3, Meat Rendering Plants. Blood can
be used in human food only if it is kept completely sterile by removal from the animals through tubes or
syringes.
In some plants, electrical stimulation (ES) is applied to the carcasses to improve lean color, firmness,
texture, and marbling score; to improve bleeding of carcasses; and to make removal of the hides easier.
Electrical stimulation also permits rapid chilling by hastening the onset of rigor before temperatures drop to
the cold shortening range. If muscles re ach temperatures below 15° to 16°C(59°to61°F) before they have
attained rigor, a contraction known as cold shortening occurs, which results in much less tender meat. In
some cases ES is applied to control the fall of pH value. Meat with a low pH value will be pale, soft, and
exudative (PSE meat). Meat with a high pH value may be dark, firm, and dry (DFD meat). It has been
claimed that ES enhances tenderness, primarily through the hastening of the onset of rigor and prevention of
cold shortening. Both high-voltage (>500 volts) and low-voltage (30 to 90 volts) ES systems can be used.
6/97 Food And Agricultural Industry 9.5.1-1
-------
VOC EMISSIONS
PM EMISSIONS
4
BLOOD
IMMOBILIZING
AND
EXSANGUINATKDN
PORK ONLY
SCALDING OR
SINGEING
HEADING AND
SHANKING
LEATHER
TANNING
SIDING, OPENING
AND BACKING
EVISCERATING
AND SPLITTING
WASHING
WEIGHING, AND " VOC EMISSIONS
SANITIZING
1
CHILLING
BREAKDOWN
T
SMOKING, CURING,
PROCESSING FOR
SPECIFIC PRODUCTS
PACKAGING U
9.5.1-2
EMISSION FACTORS
6/97
-------
After exsanguination, the actual "dressing", or cleaning, of the carcasses begins. The first step is to
separate the esophagus from the trachea, called "rodding the weasand". Alternatively, this can be done after
the chest cavity has been opened. This separation aids in evisceration. After separation, a knot is made in the
esophagus, or a band is put around it to prevent the contents of the rumen (first stomach) from spilling and
contaminating the carcass.
Next, the skin is removed from the head, and the head is removed from the carcass by cutting through
the Adam's apple and the atlas joint (heading). The fore and hind feet are then removed to prevent
contamination of the carcass with manure and dirt dropped from the hooves (shanking or legging). Each of
the legs is then skinned.
The hide is then opened down the middle of the ventral side over the entire length of the carcass. The
hide is removed from the middle down over the sides (siding). Air or electrically powered rotary skinning
knives are often used to make skinning easier. Care is taken to avoid cutting or scoring the hide, as this
decreases its value for leather.
After siding, the carcass is opened (opening). First, a cut is made through the fat and muscle at the
center of the brisket with a knife. Then a saw is used to cut through the sternum. The hind quarters are
separated with a saw or knife. The tail is skinned and then removed two joints from the body. After
removing the tail, the hide is completely removed (backing). Hides are collected, intermediate preserving
operations performed, and the preserved hides sent to tanners for processing into leather. More information
on leather tanning processes can be found in AP-42 Section 9.15, Leather Tanning.
After the hide is removed, the carcass is eviscerated. With a knife, the abdomen of the carcass is
opened from top to bottom. The fat and membranes that hold the intestines and bladder in place are
loosened, and the ureters connecting the bladder and the kidneys are cut. The liver is removed for inspection.
The previously loosened esophagus is pulled up through the diaphragm to allow the abdominal organs to fall
freely into an inspection cart. The diaphragm membrane is cut and the thoracic organs are removed.
A handsaw or electric saw is used to cut through the exact center of the backbone to split the beef
carcass into sides (halving or splitting). Inedible material is collected and sent to a rendering plant for further
processing. More information on meat rendering processes can be found in AP-42 Section 9.5.3, Meat
Rendering Plants.
After dressing, the carcasses are washed to remove any remaining blood or bone dust. The carcasses
may also be physically or chemically decontaminated. The simplest physical decontamination method
involves spraying the carcass with high pressure hot water or steam. A variety of chemical decontaminants
may be used as well; acetic and lactic acids are the most widely used and appear to be the most effective. In
addition, the following may be used: the organic acids, adipic, ascorbic, citric, fumaric, malic, propionic, and
sorbic; aqueous solutions of chlorine, hydrogen peroxide, beta-propiolactone, and glutaraldehyde; and
inorganic acids, including hydrochloric and phosphoric.
After the carcasses are dressed and washed, they are weighed and chilled. A thorough chilling during
the first 24 hours is essential, otherwise the carcasses may sour. Air chillers are most common for beef sides.
A desirable temperature for chilling warm beef carcasses is 0°C (32°F). Because a group of warm carcasses
will raise the temperature of a chill room considerably, it is good practice to lower the temperature of the
room to 5 ° below freezing (-3 °C [27°F]) before the carcasses are moved in. Temperatures more severe than
this can cause cold shortening, an intense shortening of muscle fibers, which brings about toughening.
6/97 Food And Agricultural Industry 9.5.1-3
-------
Beef undergoes maturation and should be held for at least a week (preferably longer) at 0°C (32°F)
before butchery into retail joints. In the past, sides remained intact up to the point of butchery, but it is now
common practice to break down the carcasses into primal joints (wholesale cuts), which are then vacuum
packed. Preparation of primal joints in packing plants reduces refrigeration and transport costs, and is a
convenient pre-packing operation for retailers.
Some meat products are smoked or cured prior to market. More information on smoking and curing
processes can be found in AP-42 Section 9.5.2, Meat Smokehouses.
In the manufacture of frankfurters (hot dogs) and other beef sausages, a mix of ground lean meat and
ground fat are blended together; then spices, preservatives, extenders, and other ingredients are blended with
the mixture. The mix is transferred to the hopper of the filling machine and fed to a nozzle by a piston pump.
The casing, either natural or artificial, is filled from the nozzle on a continuous basis and linked, either
manually or mechanically, to form a string of individual frankfurters or sausages.
9.5.1.2.2 Pork Processing3'7 -
Animals are delivered from the market or farm to the meat plant and are placed in holding areas.
These holding areas should have adequate facilities for the inspection of livestock, including walkways over
pens, crushes, and other facilities. Sick animals and those unfit for human consumption are identified and
removed from the normal processing flow. Plants should have separate isolation and holding pens for these
animals, and may have separate processing facilities. The live animals are weighed prior to processing so
that yield can be accurately determined.
Hogs must be rendered completely unconscious, in a state of surgical anesthesia, prior to being
shackled and hoisted for exsanguination. In large commercial operations, a series of chutes and restrainer
conveyers move the hogs into position for stunning. The V restrainer/conveyer, or similar system, is used in
most large hog processing operations. Hogs must be stunned with a federally acceptable device (mechanical,
chemical, or electrical). Mechanical stunning involves the use of a compression bolt with either a mushroom
head or a penetrating head. The force may be provided with compressed air or with a cartridge. Mechanical
stunning is largely confined to smaller operations. Chemical stunning involves the use of CO2, which reduces
blood oxygen levels, causing the animals to become anesthetized. Electrical stunning involves the use of an
electric current and two electrodes placed on the head.
Deep stunning, which was approved by the U.S. Department of Agriculture, Food and Safety
Inspection Service in 1985, requires more amperage and voltage and a third electrode attached to the back or
a foot. Stunning causes the heart to stop beating (cardiac arrest). The stunned animals undergo
exsanguination (sticking) and blood collection in the same manner as described for cattle.
Hog carcasses, unlike cattle carcasses, generally are not skinned after exsanguination. Instead, the
carcasses are dropped into scalding water which loosens the hair for subsequent removal. The carcasses
should be kept under water and continually moved and turned for uniform scalding. In large plants, carcasses
enter the scalding tub and are carried through the tub by a conveyer moving at the proper speed to allow the
proper scalding time. During the hard-hair season (September-November), the water temperature should be
59° to 60°C (139° to 140°F) and the immersion period 4 to 4-1/2 minutes, while in the easy-hair season
(February-March), a temperature of 58°C (136°F) for 4 minutes is preferable. In small plants without
automation, hair condition is checked periodically during the scalding period. Some plants use an alternative
to scalding that involves passing the carcass through gas flames to singe the hair. The hair is then removed
by rotating brushes and water sprays, and the carcass is rinsed.
9.5.1-4 EMISSION FACTORS 6/97
-------
Various dehairing machines, sometimes called "polishers", are manufactured to remove hair from the
scalded pork carcasses. The dehairing process is begun with a dehairing machine, which uses one or more
cylinders with metal tipped rubber beaters to scour the outside of the carcasses. Hot water (60°C [ 140°F]) is
sprayed on the carcasses as they pass through the dehairer moving toward the discharge end. The carcasses
are removed from this machine, hand scraped, then hoisted again, hind quarters up. The carcasses are hand-
scraped again from the top (hind quarters) down. Any remaining hairs can be removed by singeing with a
propane or similar torch. Once the remaining hairs have been singed, the carcasses are scraped a final time
and washed thoroughly from the hind feet to the head. Some plants pass the carcasses through a singeing
machine, which singes any remaining hairs from the carcasses.
Atone time, it was popular to dip dehaired carcasses into a hot solution (121° to 149°C [250° to
300°F]) of rosin and cottonseed oil for a period of six to eight seconds. When the rosin coating plasticized
after cooling, it was stripped by pull-rolling it down the carcass, taking with it the remaining hair, stubble,
and roots. However, in recent years, many packers have discontinued its use, turning instead to mechanical
brushes and torches to completely clean dehaired pork carcasses.
In some plants, hogs are skinned after exsanguination. The head and belly of the carcass are hand-
skinned, and the legs are either hand-skinned or removed. Then the carcass is hoisted, hind quarters up, and
placed under tension. A second hoist is connected to the loose head and leg skin and tightened to pull the
remaining skin from the carcass. The removed pigskins are trimmed, salted, folded, and stored in 50-gallon
drums.
After scalding and dehairing, singeing, or skinning, the head is severed from the backbone at the atlas
joint, and the cut is continued through the windpipe and esophagus. The head is inspected, the tongue is
dropped, and the head is removed from the carcass. The head is cleaned, washed, and an inspection stamp is
applied.
Following heading, the carcass is eviscerated. The hams are separated, the sternum is split, the
ventral side is opened down the entire length of the carcass, and the abdominal organs are removed. The
thoracic organs are then freed. All of the internal organs are inspected, those intended for human
consumption are separated, and the remainder are discarded into a barrel to be shipped to the rendering plant.
As mentioned previously, more information on meat rendering can be found in AP-42 Section 9.5.3, Meat
Rendering Plants.
After evisceration, the carcass is split precisely in half. Glands and blood clots in the neck region are
removed, the leaf fat and kidneys are removed, and the hams are faced (a strip of skin and fat is removed to
improve appearance).
The carcass is then washed from the top down to remove any bone dust, blood, or bacterial
contamination. A mild salt solution (0.1 M KC1) weakens bacterial attachment to the carcass and makes the
bacteria more susceptible to the sanitization procedure, especially if the sanitizing solution is applied
promptly. Dilute organic acids (2 percent lactic acid and 3 percent acetic acid) are good sanitizers. In large
operations, carcass washing is automated. As the carcass passes through booths on the slaughter line, the
proper solutions are applied at the most effective pressure.
After washing and sanitizing, the carcass is inspected one final time, weighed, and the inspection
stamp is applied to each wholesale cut. The carcass is then placed in a cooler at 0° to 1 °C (32° to 34 °F)
with air velocity typically 5 to 15 mph, equating to -5 ° C (23 ° F) wind chill, for a 24-hour chill period. For
thorough chilling, the inside temperature of the ham should reach at least 3 °C (37°F). With accelerated (hot)
processing, the carcass may be held (tempered) at an intermediate temperature of 16°C (60°F) for several
6/97 Food And Agricultural Industry 9.5.1-5
-------
hours, or be boned immediately. When large numbers of warm carcasses are handled, the chill room is
normally precooled to a temperature several degrees below freezing -3°C (27 °F), bringing the wind chill to
-9°C (16°F) to compensate for the heat from the carcasses.
Spray chilling is permitted by the U.S.D.A. to reduce cooler shrink. Spray chilling solutions may
contain up to 5 ppm available chlorine, which acts a sanitizer. At least one plant sends carcasses directly
from the kill floor through a freezer, to produce a brightly colored pork with reduced carcass shrink.
Following cooling, pork carcasses are often divided into deboned primal joints for distribution. The primal
joints may be vacuum packed. To manufacture pork sausages, ground lean meat and ground fat are blended
together and processed in the same manner as that described for beef sausages in Section 9.5.1.2.1.
9.5.1.2.3 Other Meat Processing-
Other meats undergo processes similar to those described above for beef and pork processing. These
other meats include veal, lamb, mutton, goat, horse (generally for export), and farm-raised large game
animals.
9.5.1.3 Emissions And Controls
No emission data quantifying VOC, HAP, or PM emissions from the meat packing industry were
identified during the development of this report. However, engineering judgment and comparison of meat
packing plant processes with similar processes in other industries may provide an estimation of the types of
emissions that might be expected from meat packing plant operations.
Animal holding areas, feed storage, singeing operations, and other heat sources (including boilers)
may be sources of PM and PM-10 emissions. Carbon dioxide stunning operations may be sources of CO2
emissions. Animal holding areas, scalding tanks, singeing operations, rosin dipping (where still used),
sanitizing operations, wastewater systems, and heat sources may be sources of VOC, HAP, and other criteria
pollutant emissions.
Potential emissions from boilers are addressed in AP-42 Sections 1.1 through 1.4 (Combustion).
Meat smokehouses, meat rendering operations, and leather tanning may be sources of air pollutant emissions,
but these sources are included in other sections of AP-42 and are not addressed in this section.
A number of VOC and particulate emission control techniques are potentially available to the meat
packing industry. These options include the traditional approaches of wet scrubbers, dry sorbants, and
cyclones. Other options include condensation and chemical reaction. No information is available for the
actual controls used at meat packing plants. The controls presented in this section are ones that theoretically
could be used. The specific type of control device or combination of devices would vary from facility to
facility depending upon the particular nature of the emissions and the pollutant loading in the gas stream.
The VOC emissions from meat packing operations are likely to be very low and associated with a high
moisture content.
Control of VOC from a gas stream can be accomplished using one of several techniques, but the
most common methods are absorption, adsorption, and afterburners. Absorptive methods encompass all
types of wet scrubbers using aqueous solutions to absorb the VOC. The most common scrubber systems are
packed columns or beds, plate columns, spray towers, or other types of towers. Most scrubber systems
require a mist eliminator downstream of the scrubber.
Gas adsorption is a relatively expensive technique and may not be applicable to a wide variety of
pollutants. Adsorptive methods usually include one of four main adsorbents: activated carbon, activated
9.5.1-6 EMISSION FACTORS 6/97
-------
alumina, silica gel, or molecular sieves. Of these four, activated carbon is the most widely used for VOC
control, and the remaining three are used for applications other than pollution control.
Afterburners, or thermal incinerators, are add-on combustion control devices in which VOC's are
oxidized to CO2, water, sulfur oxides, and nitrogen oxides. The destruction efficiency of an afterburner is
primarily a function of the operating temperature and residence time at that temperature. A temperature
above 816°C (1,500°F) will destroy most organic vapors and aerosols.
Particulate control commonly employs methods such as venturi scrubbers, dry cyclones, wet or dry
electrostatic precipitators (ESPs), or dry filter systems. The most common controls are likely to be the
venturi scrubbers or dry cyclones. Wet or dry ESPs are used depending upon the particulate loading of the
gas stream.
Condensation methods and scrubbing by chemical reaction may be applicable techniques depending
upon the type of emissions. Condensation methods may be either direct contact or indirect contact. The shell
and tube indirect method is the most common technique. Chemical reactive scrubbing may be used for odor
control in selective applications.
References for Section 9.5.1
1. Bureau of the Census, U. S. Department of Commerce, 1992 Census Of Manufactures, Industry
Series, MC92-I-20A, Meat Products, Industries 2011, 2013, and 2015, Washington, D.C., U. S.
Government Printing Office, June 1995.
2. USDA, National Agricultural Statistics Service, Agricultural Statistics Board, 1995 Livestock
Slaughter Annual Summary, March 14,1996.
3. J. R. Romans, et al., The Meat We Eat, Thirteenth Edition, Interstate Publishers, Inc., Danville, IL,
1994.
4. M. D. Judge, et al., Principles Of Meat Science, Second Edition, Kendall/Hunt Publishing Company,
Dubuque, IA, 1989.
5. A. H. Varnam and J. P. Sutherland, Meat And Meat Products, Technology, Chemistry, And
Microbiology, Chapman & Hall, New York, NY, 1995.
6. R. A. Lawrie, Meat Science, Fifth Edition, Pergamon Press, New York, NY, 1991.
7. N. R. P. Wilson, ed., Meat And Meat Products, Factors Affecting Quality Control, Applied Science
Publishers, Inc., Englewood, NJ, 1981.
6/97 Food And Agricultural Industry 9.5.1-7
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9.5.2 Meat Smokehouses
9.5.2.1 General1'3'7'9
Meat smokehouses are used to add flavor, color, and aroma to various meats, including pork,
beef, poultry, and fish. Smokehouses were at one time used to smoke food for preservation, but
refrigeration systems have effectively eliminated this use.
Four operations are typically involved in the production of smoked meat: (1) tempering or
drying, (2) smoking, (3) cooking, and (4) chilling. However, not all smoked foods are cooked, thus
eliminating the cooking and chilling processes from some operations. Important process parameters
include cooking/smoking time, smoke generation temperature, humidity, smoke density, type of wood
or liquid smoke, and product type.
The two types of smokehouses that are almost exclusively used are batch and continuous
smokehouses. Figures 9.5.2-1 and 9.5.2-2 show typical batch and continuous smokehouses,
respectively. Both types of systems circulate air at the desired process conditions (temperature,
humidity, and smoke density) over the surface of the meat. In batch smokehouses, the meat is placed
on stationary racks for the entire smoking process. In continuous smokehouses, the meat is hung on
sticks or hangers and then conveyed through the various zones (smoking, heating, and chilling) within
the smokehouse. Following processing in the smokehouse, the product is packaged and stored for
shipment.
Several methods are used to produce the smoke used in smokehouses. The most common
method is to pyrolyze hardwood chips or sawdust using smoke generators. In a typical smoke
generator, hardwood chips or sawdust are fed onto a gas- or electrically-heated metal surface at 350°
to 400°C (662° to 752°F). Smoke is then ducted by a smoke tube into the air recirculation system in
the smokehouse. Smoke produced by this process is called natural smoke.
Liquid smoke (or artificial smoke), which is a washed and concentrated natural smoke, is also
used in smokehouses. This type of smoke (as a fine aerosol) can be introduced into a smokehouse
through the air recirculation system, can be mixed or injected into the meat, or can be applied by
drenching, spraying, or dipping.
9.5.2.2 Emissions And Controls1"2'4
Paniculate matter (PM), carbon monoxide (CO), volatile organic compounds (VOC),
polycyclic aromatic hydrocarbons (PAH), organic acids, acrolein, acetaldehyde, formaldehyde, and
nitrogen oxides have been identified as pollutants associated with meat smokehouses. The primary
source of these pollutants is the smoke used in the smokehouses. Studies cited in Reference 1 show
that almost all PM from smoke has an aerodynamic diameter of less than 2.0 micrometers (jum).
Acetic acid has been identified as the most prevalent organic acid present in smoke, followed by
formic, propionic, butyric, and other acids. Also, acetaldehyde concentrations have been shown to be
about five times greater than formaldehyde concentrations in smoke. Heating zones in continuous
smokehouses (and the cooking cycle in batch smokehouses) are a source of odor that includes small
amounts of VOC. The VOC are a result of the volatilization of organic compounds contained in the
meat or the smoke previously applied to the meat. Heating zones are typically heated with ambient
air that is passed over electrically-heated or steam-heated coils (steam from boilers used elsewhere at
the facility). Therefore, heating zones are not a source of combustion products. Factors that may
9/95 Food And Agricultural Industry 9.5.2-1
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Food And Agricultural Industry
9.5.2-3
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effect smokehouse emissions include the amount and type of wood or liquid smoke used, the type of
meat processed, the processing time, humidity, and the temperature maintained in the smoke
generators.
Control technologies used at meat smokehouses include afterburners, wet scrubbers, and
modular electrostatic precipitators (ESP). Emissions can also be reduced by controlling important
process parameters. An example of this type of process control is maintaining a temperature not
higher than about 400°C (752°F) in the smoke generator, to minimize the formation of PAH.
Afterburners are an effective control technology for PM, organic gases, and CO from
smokehouses, but energy requirements may be costly for continuous smokehouse operations. Also,
the additional air pollution resulting from afterburner fuel combustion makes afterburners a less
desirable option for controlling smokehouse emissions.
Wet scrubbers are another effective control technology for both PM and gaseous emissions.
Different types of scrubbers used include mist scrubbers, packed bed scrubbers, and vortex scrubbers.
Mist scrubbers introduce a water fog into a chamber, and exhaust gases are then fed into the chamber
and are absorbed. Packed bed scrubbers introduce the exhaust gases into a wetted column containing
an inert packing material in which liquid/gas contact occurs. Vortex scrubbers use a whirling flow
pattern to shear water into droplets, which then contact the exhaust gases. Limited test data (from
Reference 4) show a vortex scrubber (followed by a demister) achieving about 51 percent
formaldehyde removal, 85 percent total organic compound removal, 39 percent acetic acid removal,
and 69 percent PM removal. Particulate matter removal efficiencies for scrubbers can be increased
through the use of surfactants, which may enhance the capture of smoke particles that do not combine
with the scrubber water.
Elecrostatic precipitators are effective for controlling PM emissions. Combined control
technologies, such as a wet scrubber for gaseous emission control followed by an ESP for PM
removal, may also be used to control emissions from smokehouses.
Smokehouse control devices are operated during the smoking cycle and are sometimes
bypassed during the cooking and cooling cycles. Continuous smokehouses may include separate vents
for exhaust streams from the different zones, thus minimizing the air flow through the control device.
The average emission factors for meat smokehouses are shown in Tables 9.5.2-1 and 9.5.2-2.
These emission factors are presented in units of mass of pollutant emitted per mass of wood used to
generate smoke. Normally, emission factors are based on either units of raw material or units of
product. In this industry, the amount of smoke flavor applied to the meats varies; consequently the
emissions are dependent on the quantity of wood (or liquid smoke) used, rather than the quantity of
meat processed. The emission factors presented in Tables 9.5.2-1 and 9.5.2-2 were developed using
data from only two facilities and, consequently, may not be representative of the entire industry.
9.5.2-4 EMISSION FACTORS 9/95
-------
Table 9.5.2-1. EMISSION FACTORS FOR BATCH AND CONTINUOUS
MEAT SMOKEHOUSES2
EMISSION FACTOR RATING: D
Process
Batch smokehouse, smoking
cycleb
(SCC 3-02-013-02)
Continuous smokehouse, smoke
zone
(SCC 3-02-013-04)
Continuous smokehouse, smoke
zone, with vortex wet scrubber
and demisterd
(SCC 3-02-013-04)
Filterable PM
PM
23
66
13
PM-10
NDC
ND°
NDC
Condensible PM
Inorganic
11
36
9.8
Organic
19
39
6.0
Total
30
75
16
Total PM
PM
53
140
29
PM-10
ND°
NDC
NDC
a Emission factor units are Ib/ton of wood or sawdust used. ND = no data available. SCC = Source
Classification Code.
b Reference 5.
c Although data are not directly available, Reference 1 states that all PM from smoke is less than
2 micrometers in aerodynamic diameter.
d References 4-6.
Table 9.5.2-2. EMISSION FACTORS FOR BATCH AND
CONTINUOUS MEAT SMOKEHOUSES51
Process
Batch smokehouse, smoking
cycle*5
(SCC 3-02-013-02)
Batch smokehouse, cooking
cycle
(SCC 3-02-013-03)
Continuous smokehouse,
smoke zonec
(SCC 3-02-013-04)
Continuous smokehouse,
smoke zone, with vortex
wet scrubber and demisterd
(SCC 3-02-013-04)
Continuous smokehouse,
heat zone
(SCC 3-02-013-05)
VOC
44
ND
17
4.4
ND
EMISSION
FACTOR
RATING
D
NA
D
E
NA
Formaldehyde
ND
ND
1.3
0.62
ND
EMISSION
FACTOR
RATING
NA
NA
E
E
NA
Acetic
Acid
ND
ND
4.5
2.8
ND
EMISSION
FACTOR
RATING
NA
NA
E
E
NA
a Emission factor units are Ib/ton of wood or sawdust used, unless noted. ND = no data available. NA = not
applicable. SCC = Source Classification Code.
Reference 5. VOC, measured as methane.
c References 5-6. VOC, measured as methane.
d Reference 4. VOC, measured as methane. VOCs were measured on a gas chromatograph calibrated against
acetaldehyde, and the results were converted to a methane basis.
9/95
Food And Agricultural Industry
9.5.2-5
-------
References For Section 9.5.2
1. J. R. Blandford, "Meat Smokehouses", in Chapter 13, Food And Agriculture Industry, Air
Pollution Engineering Manual, Van Nostrand Reinhold Press, 1992.
2. Written communication from J. M. Jaeckels, Oscar Mayer Foods Corporation, Madison, WI,
to S. Lindem, Wisconsin Department of Natural Resources, Madison, WI, April 1, 1992.
3. Joseph A. Maga, Smoke In Food Processing, CRC Press, Incorporated, Boca Raton, FL,
1988.
4. KSI-2 & KSI-3 Continuous Smokehouses Stack Emissions Testing, Hillshire Farm & Kahn's,
New London, WI, September 19-20, 1991.
5. Report On Diagnostic Testing, Oscar Mayer Foods Corporation, Madison, WI, January 13,
1994.
6. Written correspondence from D. Sellers, Wisconsin Department of Natural Resources,
Madison, WI, to Wisconsin Department of Natural Resources Files, Madison, WI, June 17,
1994.
7. Written communication from J. M. Jaeckels, BT2, Inc., Madison, WI, to D. Safriet, U. S.
Environmental Protection Agency, Research Triangle Park, NC, December 15, 1994.
8. Telephone communication between B. L. Shrager, Midwest Research Institute, Gary, NC, and
J.M. Jaeckels, BT2, Inc., Madison, WI, March 16 and 17, 1995.
9. Emission Factor Documentation, AP-42 Section 9.5.2, Meat Smokehouses, EPA Contract
No. 68-D2-0159, Midwest Research Institute, Cary, NC, September 1995.
9.5.2-6 EMISSION FACTORS 9/95
-------
9.5.3 Meat Rendering Plants
9.5.3.1 General1
Meat rendering plants process animal by-product materials for the production of tallow,
grease, and high-protein meat and bone meal. Plants that operate in conjunction with animal
slaughterhouses or poultry processing plants are called integrated rendering plants. Plants that collect
their raw materials from a variety of offsite sources are called independent rendering plants.
Independent plants obtain animal by-product materials, including grease, blood, feathers, offal, and
entire animal carcasses, from the following sources: butcher shops, supermarkets, restaurants,
fast-food chains, poultry processors, slaughterhouses, farms, ranches, feedlots, and animal shelters.
The two types of animal rendering processes are edible and inedible rendering. Edible
rendering plants process fatty animal tissue into edible fats and proteins. The plants are normally
operated in conjunction with meat packing plants under U.S. Department of Agriculture, Food Safety
and Inspection Services (USDA/FSIS) inspection and processing standards. Inedible rendering plants
are operated by independent Tenderers or are part of integrated rendering operations. These plants
produce inedible tallow and grease, which are used in livestock and poultry feed, soap, and
production of fatty-acids.
9.5.3.2 Process Description1"3
Raw Materials —
Integrated rendering plants normally process only one type of raw material, whereas
independent rendering plants often handle several raw materials that require either multiple rendering
systems or significant modifications in the operating conditions for a single system.
Edible Rendering —
A typical edible rendering process is shown in Figure 9.5.3-1. Fat trimmings, usually
consisting of 14 to 16 percent fat, 60 to 64 percent moisture, and 22 to 24 percent protein, are
ground and then belt conveyed to a melt tank. The melt tank heats the materials to about 43 °C
(110°F), and the melted fatty tissue is pumped to a disintegrator, which ruptures the fat cells. The
proteinaceous solids are separated from the melted fat and water by a centrifuge. The melted fat and
water are then heated with steam to about 93°C (200°F) by a shell and tube heat exchanger. A
second-stage centrifuge then separates the edible fat from the water, which also contains any
remaining protein fines. The water is discharged as sludge, and the "polished" fat is pumped to
storage. Throughout the process, direct heat contact with the edible fat is minimal and no cooking
vapors are emitted. For this reason, no emission points are designated in Figure 9.5.3-1.
Inedible Rendering —
There are two processes for inedible rendering: the wet process and the dry process. Wet
rendering is a process that separates fat from raw material by boiling in water. The process involves
addition of water to the raw material and the use of live steam to cook the raw material and
accomplish separation of the fat. Dry rendering is a batch or continuous process that dehydrates raw
material in order to release fat. Following dehydration in batch or continuous cookers, the melted fat
and protein solids are separated. At present, only dry rendering is used in the United States. The
wet rendering process is no longer used because of the high cost of energy and of an adverse effect
9/95 Food And Agriculture 9.5.3-1
-------
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EMISSION FACTORS
9/95
-------
on the fat quality. Table 9.5.3-1 shows the fat, protein, and moisture contents for several raw
materials processed by inedible rendering plants.
Batch Rendering Process —
In the batch process, the raw material from the receiving bin is screw conveyed to a crusher
where it is reduced to 2.5 to 5 centimeters (cm) (1 to 2 inches [in.]) in size to improve cooking
efficiency. Cooking normally requires 1.5 to 2.5 hr, but adjustments in the cooking time and
temperature may be required to process the various materials. A typical batch cooker is a horizontal,
cylindrical vessel equipped with a steam jacket and an agitator. To begin the cooking process the
cooker is charged with raw material, and the material is heated to a final temperature ranging from
121° to 135°C (250° to 275 °F). Following the cooking cycle, the contents are discharged to the
percolator drain pan. Vapor emissions from the cooker pass through a condenser where the water
vapor is condensed and noncondensibles are emitted as VOC emissions.
The percolator drain pan contains a screen that separates the liquid fat from the protein solids.
From the percolator drain pan, the protein solids, which still contain about 25 percent fat, are
conveyed to the screw press. The screw press completes the separation of fat from solids, and yields
protein solids that have a residual fat content of about 10 percent. These solids, called cracklings, are
then ground and screened to produce protein meal. The fat from both the screw press and the
percolator drain pan is pumped to the crude animal fat tank, centrifuged or filtered to remove any
remaining protein solids, and stored in the animal fat storage tank.
Continuous Rendering Process —
Since the 1960, continuous rendering systems have been installed to replace batch systems at
some plants. Figure 9.5.3-2 shows the basic inedible rendering process using the continuous process.
The system is similar to a batch system except that a single, continuous cooker is used rather than
several parallel batch cookers. A typical continuous cooker is a horizontal, steam-jacketed cylindrical
vessel equipped with a mechanism that continuously moves the material horizontally through the
cooker. Continuous cookers cook the material faster than batch cookers, and typically produce a
higher quality fat product. From the cooker, the material is discharged to the drainer, which serves
the same function as the percolator drain pan in the batch process. The remaining operations are
generally the same as the batch process operations.
Current continuous systems may employ evaporators operated under vacuum to remove
moisture from liquid fat obtained using a preheater and a press. In this system, liquid fat is obtained
by precooking and pressing raw material and then dewatered using a heated evaporator under
vacuum. The heat source for the evaporator is hot vapors from the cooker/dryer. The dewatered fat
is then recombined with the solids from the press prior to entry into the cooker/dryer.
Blood Processing And Drying —
Whole blood from animal slaughterhouses, containing 16 to 18 percent total protein solids, is
processed and dried to recover protein as blood meal. At the present time, less than 10 percent of the
independent rendering plants in the U. S. process whole animal blood. The blood meal is a valuable
ingredient in animal feed because it has a high lysine content. Continuous cookers have replaced
batch cookers that were originally used in the industry because of the improved energy efficiency and
product quality provided by continuous cookers. In the continuous process, whole blood is
introduced into a steam-injected, inclined tubular vessel in which the blood solids coagulate. The
coagulated blood solids and liquid (serum water) are then separated in a centrifuge, and the blood
solids dried in either a continuous gas-fired, direct-contact ring dryer or a steam tube, rotary dryer.
9/95 Food And Agriculture 9.5.3-3
-------
Table 9.5.3-1. COMPOSITION OF RAW MATERIALS FOR
INEDIBLE RENDERING"
Source
Tallow/Grease,
wt %
Protein Solids,
wt %
Moisture,
wt %
Packing house offalb and bone
Steers
Cows
Calves
Sheep
Hogs
Poultry offal
Poultry feathers
30-35
10-20
10-15
25-30
25-30
10
None
15-20
20-30
15-20
20-25
10-15
25
33
45-55
50-70
65-75
45-55
55-65
65
67
Dead stock (whole animals)
Cattle
Calves
Sheep
Hogs
Butcher shop fat and bone
Blood
Restaurant grease
12
10
22
30
31
None
65
25
22
25
28
32
16-18
10
63
68
53
42
37
82-84
25
* Reference 1.
b Waste parts; especially the entrails and similar parts from a butchered animal.
9.5.3-4
EMISSION FACTORS
9/95
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Poultry Feathers And Hog Hair Processing —
The raw material is introduced into a batch cooker, and is processed for 30 to 45 minutes at
temperatures ranging from 138° to 149°C (280° to 300°F) and pressures ranging from (40
to 50 psig). This process converts keratin, the principal component of feathers and hog hair, into
amino acids. The moist meal product, containing the amino acids, is passed either through a hot air,
ring-type dryer or over steam-heated tubes to remove the moisture from the meal. If the hot air dryer
is used, the dried product is separated from the exhaust by cyclone collectors. In the steam-heated
tube system, fresh air is passed countercurrent to the flow of the meal to remove the moisture. The
dried meal is transferred to storage. The exhaust gases are passed through controls prior to discharge
to the atmosphere.
Grease Processing —
Grease from restaurants is recycled as another raw feed material processed by rendering
plants. The grease is bulk loaded into vehicles, transported to the rendering plant, and discharged
directly to the grease processing system. During processing, the melted grease is first screened to
remove coarse solids, and then heated to about 93°C (200°F) in vertical processing tanks. The
material is then stored in the processing tank for 36 to 48 hr to allow for gravity separation of the
grease, water, and fine solids. Separation normally results in four phases: (1) solids, (2) water,
(3) emulsion layer, and (4) grease product. The solids settle to the bottom and are separated from the
water layer above. The emulsion is then processed through a centrifuge to remove solids and another
centrifuge to remove water and any remaining fines; the grease product is skimmed off the top.
9.5.3.3 Emissions And Controls1"5
Emissions —
Volatile organic compounds (VOCs) are the primary air pollutants emitted from rendering
operations. The major constituents that have been qualitatively identified as potential emissions
include organic sulfides, disulfides, C-4 to C-7 aldehydes, trimethylamine, C-4 amines, quinoline,
dimethyl pyrazine, other pyrazines, and C-3 to C-6 organic acids. In addition, lesser amounts of C-4
to C-7 alcohols, ketones, aliphatic hydrocarbons, and aromatic compounds are potentially emitted.
No quantitative emission data were presented. Historically, the VOCs are considered an odor
nuisance in residential areas in close proximity to rendering plants, and emission controls are directed
toward odor elimination. The odor detection threshold for many of these compounds is low; some as
low as 1 part per billion (ppb). Of the specific constituents listed, only quinoline is classified as a
hazardous air pollutant (HAP). In addition to emissions from rendering operations, VOCs may be
emitted from the boilers used to generate steam for the operation.
Emissions from the edible rendering process are not considered to be significant because no
cooking vapors are emitted and direct heat contact with the edible fat is minimal. Therefore, these
emissions are not discussed further.
For inedible rendering operations, the primary sources of VOC emissions are the cookers and
the screw press. Other sources of VOC emissions include blood and feather processing operations,
dryers, centrifuges, tallow processing tanks, and percolator pans that are not enclosed. Raw material
may also be a source of VOC emissions, but if the material is processed in a timely manner, these
emissions are minimal.
In addition to VOC emissions, paniculate matter (PM) is emitted from grinding and screening
of the solids (cracklings) from the screw press and other rendering operations such as dryers
processing blood and feathers. No emission data quantifying VOC, HAP, or PM emissions from the
9.5.3-6 EMISSION FACTORS 9/95
-------
rendering process are available for use in developing emission factors. Only test data for a blood
dryer operation were identified.
Controls —
Emissions control at rendering plants is based primarily on the elimination of odor. These
controls are divided into two categories: (1) those controlling high intensity odor emissions from the
rendering process, and (2) those controlling plant ventilating air emissions. The control technologies
that are typically used for high intensity odors from rendering plant process emissions are waste heat
boilers (incinerators) and multistage wet scrubbers.
Boiler incinerators are a common control technology because boilers can be used not only as
control devices but also to generate steam for cooking and drying operations. In waste heat boilers,
the waste stream can be introduced into the boiler as primary or secondary combustion air. Primary
combustion air is mixed with fuel before ignition to allow for complete combustion, and secondary
combustion air is mixed with the burner flame to complete combustion. Gaseous waste streams that
contain noncondensibles are typically "cleaned" in a combination scrubber and entrainment separator
before use as combustion air.
Multistage wet scrubbers are equally as effective as incineration for high intensity odor
control and are used to about the same extent as incinerators. Sodium hypochlorite is considered to
be the most effective scrubbing agent for odor removal, although other oxidants can be used.
Recently, chlorine dioxide has been used as an effective scrubbing agent. Venturi scrubbers are often
used to remove PM from waste streams before treatment by the multistage wet scrubbers. Plants that
are located near residential or commercial areas may treat process and fugitive emissions by ducting
the plant ventilation air through a single-stage wet scrubbing system to minimize odorous emissions.
In addition to the conventional scrubber control technology, activated carbon adsorption and
catalytic oxidation potentially could be used to control odor; however, no rendering plants currently
use these technologies. Recently, some plants have installed biofilters to control emissions.
No data are currently available for VOC or particulate emissions from rendering plants. The
only available data are for emissions from blood dryers, which is an auxiliary process in meat
rendering operations. Less than 10 percent of the independent rendering plants in the U. S. process
whole blood. Table 9.5.3-2 provides controlled emission factors in English units for particulate
matter (filterable and condensible), hydrogen sulfide, and ammonia from natural gas, direct-fired
blood dryers. The filterable PM was found to be 100 percent PM-10. Emission factors are
calculated on the basis of the weight of dried blood meal product. In addition to natural gas, direct-
fired dryers, steam-coil, indirect blood dryers (SCC 3-02-038-12) are also used in meat rendering
plants. No emission data were found for this type of dryer. The emission control system in
Reference 4 consisted of a cyclone separator for collection of the blood meal product followed by a
venturi wet scrubber and three packed bed scrubbers in series. The scrubbing medium for the three
packed bed scrubbers was a sodium hypochlorite solution. The emission control system in
Reference 5 was a mechanical centrifugal separator.
9/95 Food And Agriculture 9.5.3-7
-------
Table 9.5.3-2. EMISSION FACTORS FOR CONTROLLED BLOOD DRYERS
EMISSION FACTOR RATING: E
Pollutant
Emissions, lb/tona
Filterable PM-10b (SCC 3-02-038-11)
Condensible PMb (SCC 3-02-038-11)
Hydrogen sulfide0 (SCC 3-02-038-11)
Ammonia0 (SCC 3-02-038-11)
0.76
0.46
0.08
0.60
" Emission factors based on weight of dried blood meal product. Emissions are for natural gas,
direct-fired dryers.
b References 4-5.
c Reference 4.
References For Section 9.5.3
1. W.H. Prokop, Section on rendering plants, in Chapter 13, "Food And Agriculture Industry",
Air Pollution Engineering Manual, Van Nostrand Reinhold Press, 1992.
2. H.J. Rafson, Odor Emission Control For The Food Industry, Food And Technology,
June 1977.
3. Emission Factor Documentation for AP-42 Section 9,5.3, Meat Rendering Plants,
EPA Contract No. 68-D2-0159, Midwest Research Institute , Kansas City, MO,
September 1995.
4. Blood Dryer Operation Stack Emissions Testing, Environmental Technology and Engineering
Corporation, Elm Grove, WI, September 1989.
5. Blood Dryer Paniculate Emission Compliance Test, Interpoll Report No. 7-2325, Interpoll
Laboratories, Inc., Circle Pines, MN, January 1987.
9.5.3-8 EMISSION FACTORS 9/95
-------
9.5.4 Manure Processing
[Work In Progress]
1/95 Food And Agricultural Industries 9.5.4-1
-------
9.5.5 Poultry Slaughtering
[Work In Progress]
1/95 Food And Agricultural Industries 9.5.5-1
-------
9.6.1 Natural And Processed Cheese
9.6.1.1 General1'3
The United States is one of the largest producers of cheese in the world. The total number of
industry establishments in the United States in 1995 was 432. In 1995, total natural cheese production in the
U. S., excluding cottage cheeses, was 6.9 billion pounds, and total processed cheese production was
2.3 billion pounds. Wisconsin is the leading producer of cheese in the United States, accounting for over 30
percent of all cheese production in the country.
Popular types of natural cheeses include unripened (e. g., cottage cheese, cream cheese), soft (e. g.,
Brie, Camembert), semi-hard (e. g., Brick, Muenster, Roquefort, Stilton), hard (e. g., Colby, Cheddar), blue
veined (e. g., Blue, Gorgonzola), cooked hard cheeses (e. g., Swiss, Parmesan), and pasta filata (stretched
curd, e. g., Mozzarella, Provolone). Examples of processed cheeses include American cheese and various
cheese spreads, which are made by blending two or more varieties of cheese or blending portions of the same
type of cheese that are in different stages of ripeness.
9.6.1.2 Process Description4'9
The modern manufacture of natural cheese consists of four basic steps: coagulating, draining, salting,
and ripening. Processed cheese manufacture incorporates extra steps, including cleaning, blending, and
melting. No two cheese varieties are produced by the same method. However, manufacturing different
cheeses does not require widely different procedures but rather the same steps with variations during each
step, the same steps with a variation in their order, special applications, or different ripening practices. Table
9.6.1-1 presents variations in the cheesemaking process characteristic of particular cheese varieties. This
section includes a generic process description; steps specific to a single cheese variety are mentioned but are
not discussed in detail.
9.6.1.2.1 Natural Cheese Manufacture -
The following sections describe the steps in the manufacture of natural cheese. Figure 9.6.1-1
presents a general process diagram.
Milk Preparation -
Cow's milk is the most widely used milk in cheese processing. First, the milk is homogenized to
ensure a constant fat level. A standardizing centrifuge, which skims off the surplus fat as cream, is often used
to obtain the fat levels appropriate for different varieties of cheese. Following homogenization, the milk is
ready for pasteurization, which is necessary to destroy harmful micro-organisms and bacteria.
Coagulation -
Coagulation, or clotting of the milk, is the basis of cheese production. Coagulation is brought about
by physical and chemical modifications to the constituents of milk and leads to the separation of the solid part
of milk (the curd) from the liquid part (the whey). To initiate coagulation, milk is mixed with a starter, which
is a culture of harmless, active bacteria. The enzyme rennin is also used in coagulation. Most of the fat and
protein from the milk are retained in the curd, but nearly all of the lactose and some of the minerals, protein,
and vitamins escape into the whey. Table 9.6.1-1 provides the primary coagulating agents and the
coagulating times necessary for different varieties of cheese.
7/97 Food And Agricultural Industry 9.6.1 -1
-------
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9.6.1-2
EMISSION FACTORS
7/97
-------
MILK PREPARATION
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Figure 9.6.1-1. Natural cheese manufacture.
(Source Classification Code in parentheses.)
7/97
Food And Agricultural Industry
9.6.1-3
-------
Curd Treatment -
After the curd is formed, it is cut into small pieces to speed whey expulsion and increase the surface
area. The curd particles are cut into various sizes, depending on the variety of cheese being made. Cutting
the curd into small cubes reduces the moisture content of the curd, whereas creating larger cubes increases the
moisture content.
Following the cutting step, the curd is cooked, which contracts the curd particles and acts to remove
whey, develop texture, and establish moisture control. The cut curds and whey are heated and agitated.
Table 9.6.1-1 provides the cooking temperatures required to produce typical varieties of cheeses.
Curd Drainage -
The next step in cheese manufacture, drainage, involves separating the whey from the curd. Drainage
can be accelerated by either heat treatment or mechanical treatment, such as cutting, stirring, oscillating, or
pressing. After the curd is dry, it is cut into blocks which can then be filled into cheese hoops for further
draining and pressing. Table 9.6.1-1 gives the primary draining methods for a variety of cheeses.
For some cheeses, special applications and procedures occur immediately before, during, or after the
draining stage. For example, internally ripened, or blue veined, cheeses (e. g., Blue, Roquefort) are usually
seeded with penicillium powder prior to drainage. Cooked hard cheeses (e. g., Parmesan) are stirred and
warmed to accelerate and complete the separation of the whey. The separated whey may be treated and
disposed of; shipped offsite in liquid or concentrated form for use as animal feed; used to make whey cheese;
dried for lactose, mineral, or protein recovery; or dried for use as a food additive or use in the manufacture of
processed cheese.
Curd Knitting -
Knitting, or transforming, the curd allows the accumulating lactic acid to chemically change the curd;
knitting also includes salting and pressing. This step leads to the characteristic texture of different cheeses.
During the curd knitting stage, Provolone and Mozzarella cheeses are pulled and processed (these cheeses are
then kneaded, drawn, shaped, and smoothed); a bean gum or some other type of gum is added to cream cheese
to stabilize and stiffen it; and a creaming agent (cream and/or milk) is added to cottage cheese. During this
period, specific pH levels are controlled to produce different varieties of cheese (see Table 9.6.1-1).
To salt the cheese, coarse salt is spread over the surface of the cheese or the pressed cheese is
immersed in a salt solution. Salting further completes the drainage of the cheese and also affects rind
formation, growth of microorganisms, and enzyme activity. Table 9.6.1-1 provides the salting method and
salt percentage necessary to produce a particular variety of cheese.
Pressing determines the characteristic shape of the cheese by compacting the texture, extruding free
whey from the curds, and completing the curd knitting. Pressing involves confining the wet, warm curds in a
form or cloth bag. With some cheeses, vertical pressing is used; others require vacuum pressing to remove
occluded air and give a close-knit body. See Table 9.6.1-1 for the different pressing practices for various
cheeses.
Ripening -
During the ripening or curing stage, varieties of cheeses acquire their own unique textures, aromas,
appearances, and tastes through complex physical and chemical changes that are controlled as much as
possible by adjusting temperature, humidity, and duration of ripening. For all cheeses, the purpose of
ripening is to allow beneficial bacteria and enzymes to transform the fresh curd into a cheese of a specific
flavor, texture, and appearance. Cottage and cream cheeses are not ripened, and usually have a bland flavor
and soft body.
9.6.1-4 EMISSION FACTORS 7/97
-------
Some cheeses require the application of a special ripening agent to create a particular taste or texture.
For example, some cheeses rely wholly on surface bacteria and yeast applied to their exteriors for curing and
ripening (e. g., Brick, Brie, Camembert); others require injection of particular bacteria and molds (e. g., Blue)
or gas-forming microorganisms (e. g., Swiss). It is during the ripening stage that the rind or crust forms on
the cheese's surface. The rind controls the loss of moisture from the internal part of the cheese and regulates
the escape of gases released during ripening.
Preserving And Packaging -
Modern cheese packaging protects the food from microorganisms and prevents moisture loss.
Ripened cheeses must undergo special procedures during packaging for preservative reasons. Unripened
cheeses are packaged immediately after the curd is collected and must be immediately refrigerated.
Many ripened cheeses are coated in wax to protect them from mold contamination and to reduce the
rate of moisture loss. Cheeses that naturally develop a thick, tightly woven rind, such as Swiss, do not require
waxing. A second method of ripened cheese packaging involves applying laminated cellophane films to
unwaxed cheese surfaces. The most common packaging film consists of two laminated cellophane sheets and
a brown paper overlay necessary for shipping. A variation includes a metal foil wrap.
9.6.1.2.2 Processed Cheese Manufacture -
Nearly one-third of all cheese produced in the United States consists of processed cheese and
processed cheese products. There are many different types of final products in processed cheese manufacture.
These cheeses are distinguished from one another not only by their composition but by their presentation as
individual portions, individual slices, rectangular blocks, or special presentation as cylinders or tubes.
Processed cheese is made by pasteurizing, emulsifying, and blending natural cheese. Processed
cheese foods, spreads, and cold pack cheeses contain additional ingredients, such as nonfat milk solids and
condiments. Several varieties of natural cheeses may be mixed, and powdered milk, whey, cream or butter,
and water may be added. The following section describes the basic steps necessary for producing pasteurized
process cheese, the most common processed cheese.
Pasteurized Process Cheese -
Cheeses are selected to be processed from both mild and sharp cheeses. For example, American
cheese is made from Cheddar and Colby cheeses. Once selected, the cheeses must be analyzed for their fat
and moisture contents to determine the proper amount of emulsifiers and salts to be added. Cheese surfaces
are cleaned by scraping and trimming, and the rinds are removed. After cleaning, the cheese blocks are
ground in massive grinders, combined, and the cheese mixture is heated. At this point, the melted cheese
separates into a fat and serum. Emulsifiers are added to disperse the fat, and create a uniform, homogenous
mass.
The molten cheese is removed quickly from the cookers and is pumped or dropped into packaging
hoppers. The cheese is packaged in the absence of oxygen to inhibit the growth of mold. The cheese is
usually wrapped in lacquered aluminum foil or in aluminum foil-lined cardboard or plastic boxes. For sliced
processed cheese, the molten cheese is spread uniformly by chilled steel rollers and cut by rotary knives to
consumer size.
7/97 Food And Agricultural Industry 9.6.1 -5
-------
Processed Cheese Foods -
Other processed cheeses that are similar to the above in manufacturing are also commonly produced.
For example, to produce pasteurized process cheese food, one or more of the following optional dairy
ingredients are added: cream, milk, skim milk, buttermilk, and/or cheese whey. The result is a processed
cheese food that is higher in moisture and lower in fat than pasteurized process cheese. After heating,
processed cheese intended for spreading undergoes a creaming step, which includes mechanical kneading of
the hot cheese and addition of various dairy products and other additives. Other processed cheese products
include cold-packed cheese, cold-packed cheese food, and reduced fat cheeses. All processed cheeses may be
enhanced with salt, artificial colorings, spices or flavorings, fruits, vegetables, and meats.
Grated and powdered cheeses are produced by removing the moisture from one or more varieties of
cheeses and grinding, grating, or shredding the cheese(s). Mold-inhibiting ingredients and anti-caking agents
may be added as well. Dehydration takes such forms as tray drying, spray or atomized drying, and freeze
drying. Popular types of grated cheese include Parmesan, Romano, Mozzarella, and Cheddar. Cheese
powders, such as those made from Cheddar cheese, may be used to flavor pasta, or added to bread dough,
potato chips, or dips.
9.6.1.3 Emissions And Controls
Particulate emissions from cheese manufacture occur during cheese or whey drying, and may occur
when the cheese is grated or ground before drying. C02 emissions from direct-fired dryers are primarily from
the combustion of fuel, natural gas. Cheese dryers are used in the manufacture of grated or powdered
cheeses. Whey dryers are used in some facilities to dry the whey after it has been separated from the curd
following coagulation. VOC emissions may occur in the coagulation and/or ripening stages. Particulate
emissions from cheese and whey dryers are controlled by wet scrubbers, cyclones, or fabric filters. Cyclones
are also used for product recovery. Emission factors for cheese drying and whey drying in natural and
processed cheese manufacture are shown in Table 9.6.1-2.
Table 9.6.1-2. PARTICULATE EMISSION FACTORS FOR NATURAL AND
PROCESSED CHEESE MANUFACTURE3
Source
Cheese dryer
(SCC 3-02-030-20)
Whey dryer
(SCC 3-02-030-10)
Pollutant
Filterable PM
Condensible inorganic PM
Condensible organic PM
Filterable PM
Condensible PM
Average emission factor'
Ib/ton
2.5
0.29
0.44
1.24
0.31
Rating
D
D
D
D
D
Ref.
1,2,3
2,3
1,2,3
4,6,7
4,6,7
Emission factor units are Ib/ton of dry product. To convert from Ib/ton to kg/Mg, multiply by 0.5. SCC = Source
Classification Code.
b Emission factors for cheese dryers represent average values for controlled emissions based on wet scrubbers or
venturi scrubbers. Factors for whey dryers are average values for controlled emissions based on cyclones, wet
scrubbers, or fabric filters.
9.6.1-6
EMISSION FACTORS
7/97
-------
References For Section 9.6.1
1. 1992 Census Of Manufactures: Dairy Products, U. S. Department of Commerce, Bureau of Census,
Washington, DC, 1994.
2. U. S. Department of Agriculture, National Agriculture Statistics Service, Dairy Products 1995
Summary, Washington, DC, April 1996. http://usda.mannlib.comell.edu/reports
3. B. Battistotti, et al., Cheese: A Guide To The World Of Cheese And Cheesemaking, Facts On File
Publications, NY, 1984.
4. A. Eck, ed., Cheesemaking: Science And Technology, Lavoisier Publishing, New York, 1987.
5. A. Meyer, Processed Cheese Manufacture, Food Trade Press Ltd., London, 1973.
6. Newer Knowledge Of Cheese And Other Cheese Products, National Dairy Council, Rosemont, IL,
1992.
7. M.E. Schwartz, Cheesemaking Technology, Noyes Data Corporation, Park Ridge, NJ, 1973.
8. F. Kosikowski, Cheese And Fermented Milk Foods, Edwards Brothers, Ann Arbor, MI, 1977.
9. New Standard Encyclopedia, Vol.4, "Cheese", Standard Educational Corporation, Chicago, IL,
pp. 238-240.
7/97 Food And Agricultural Industry 9.6.1-7
-------
9.7 Cotton Ginning
9.7.1 General1'8
Cotton ginning takes place throughout the' area of the United States known as the Sunbelt.
Four main production regions can be designated:
• Southeast—Virginia, North Carolina, South Carolina, Georgia, Alabama, and Florida
• Mid-South—Missouri, Tennessee, Mississippi, Arkansas, and Louisiana
• Southwest—Texas and Oklahoma
• West—New Mexico, Arizona, and California
The majority of the ginning facilities are located in Texas, Mississippi, Arkansas, California, and
Louisiana.
The industry trend is toward fewer gins with higher processing capacity. In 1979,
2,332 active gins in the United States produced 14,161,000 bales of cotton. By the 1994/1995
season, the number of cotton gins in the United States dropped to 1,306, but about 19,122,000 bales
were produced. The average volume processed per gin in 1994/1995 was 14,642 bales.
Cotton ginning is seasonal. It begins with the maturing of the cotton crop, which varies by
region, and ends when the crop is finished. Each year the cotton ginning season starts in the lower
Southwest region in midsummer, continues through the south central and other geographical regions
in late summer and early autumn, and ends in the upper Southwest region in late autumn and early
winter. Overall, U. S. cotton is ginned between October 1 and December 31, with the bulk of the
crop from each geographical region being ginned in 6 to 8 weeks. During the remainder of the year,
the gin is idle.
All U. S. cotton in commercial production is now harvested by machines of two types,
picking and stripping. Machine-picked cotton accounts normally for 70 to 80 percent of the total
cotton harvested, while the rest is machine stripped. Machine picking differs from machine stripping
mainly in the method by which the cotton lint and seed are removed from the plant. Machine picking
is done by a spindle picker machine that selectively separates the exposed seed cotton from the open
capsules, or bolls. In contrast, the mechanical stripper removes the entire capsule, with lint plus
bract, leaf, and stem components in the harvested material.
Strippers collect up to six times more leaves, burs, sticks, and trash than the spindle picker
machines. This higher ratio of trash to lint requires additional equipment for cleaning and trash
extraction. Stripper-harvested cotton may produce 1,000 pounds of trash per 500-pound bale of lint,
compared to 150 pounds of trash per 500-pound bale from spindle picking.
The modular system of seed cotton storage and handling has been rapidly adopted. This
system stores seed cotton in the field after harvesting until the gin is ready to process it. Modules can
also be transported longer distances, allowing gins to increase productivity. In 1994, 78 percent of
the U.S. crop was handled in modules.
6/96 Food And Agricultural Industry 9.7-1
-------
9.7.2 Process Description2'5'7
Figure 9.7-1 is a flow diagram of a typical cotton-ginning process. Each of the five ginning
steps and associated equipment is described below.
9.7.2.1 Unloading System -
Module trucks and trailers transport cotton from the field to the gin. A pneumatic system
removes the cotton from the trailers, and either a pneumatic system or a module feeder removes the
cotton from modules. A combination conveyer and pneumatic system conveys the cotton to a
separator and feed control unit. Prior to this first separator point, some gins use a stone and green
boll trap for preliminary trash removal. The screen assembly in the separator allows air to escape but
collects the cotton and allows it to fall into the feed control unit. The conveying air flows from the
separator to a cyclone system, where it is cleaned and discharged to the atmosphere.
9.7.2.2 Seed Cotton Cleaning System -
Cotton is subjected to three basic conditioning processes-drying, cleaning, and
extracting-before it is processed for separation of lint and seed. To ensure adequate conditioning,
cotton gins typically use two conditioning systems (drying, cleaning, and extracting) in series.
Seed cotton dryers are designed to reduce lint cotton moisture content to 5 to 8 percent to
facilitate cleaning and fiber/seed separation. A high-pressure fan conveys seed cotton through the
drying system to the first seed cotton cleaner, which loosens the cotton and removes fine particles of
foreign matter (e. g., leaf trash, sand, and dirt). In the second cleaner, large pieces (e. g., sticks,
stems, and burs) are removed from the cotton by a different process, referred to as "extracting".
Different types of extractors may be used, including bur machines, stick machines, stick and bur
machines, stick and green leaf extractors, and extractor/feeders. These machines remove burs, sticks,
stems, and large leaves, pneumatically conveying them to the trash storage area. The cotton is
pneumatically conveyed to the next processing step. Typically, all conveying air is cleaned by a
cyclone before being released to the atmosphere.
9.7.2.3 Overflow System -
After cleaning, the cotton enters a screw conveyor distributor, which apportions the cotton to
the extractor/feeders at a controlled rate. The extractor/feeders drop the cotton into the gin stands at
the recommended processing rates. If the flow of cotton exceeds the limit of the extractor/feeder
systems, the excess cotton flows into the overflow hopper. A pneumatic system (overflow separator)
then returns this cotton back to the screw conveyor distributor, as required. Typically, the air from
this system is routed through a cyclone and cleaned before being exhausted to the atmosphere.
9.7.2.4 Ginning and Lint Handling System -
Cotton enters the gin stand through a "huller front", which performs some cleaning. Saws
grasp the locks of cotton and draw them through a widely spaced set of "huller ribs" that strip off
hulls and sticks. (New gin stands do not have huller ribs.) The cotton locks are then drawn into the
roll box, where fibers are separated from the seeds. After all the fibers are removed, the seeds slide
down the face of the ginning ribs and fall to the bottom of the gin stand for subsequent removal to
storage. Cotton lint is removed from the saws by a rotating brush, or a blast of air, and is conveyed
pneumatically to the lint cleaning system for final cleaning and combing. The lint cotton is removed
from the conveying airstream by a condenser that forms the lint into a batt. The lint batt is fed into
the first lint cleaner, where saws comb the lint cotton again and remove part of the remaining leaf
particles, grass, and motes. Most condensers are covered with fine mesh wire or fine perforated
metal, which acts to filter short lint fibers and some dust from the conveying air.
9.7-2 EMISSION FACTORS 6/96
-------
UNLOADING
SYSTEM
NO. 1 DRYER AND
CLEANER
EMISSIONS
(3-02-004-01)
EMISSIONS
(3-02-004-20)
STICK
MACHINE
NO 2 DRYER AND PM,oo,nK,o
CLEANER EMISSIONS
(NO. 3 DRYER AND ~ (3-02-004-21)
CLEANER
OPTIONAL) | - (3-02-004-22)
EMISSIONS
DISTRIBUTOR I 1 OVERFLOW .- (3-02-004-25)
SYSTEM
_! i ~" i - OPTIONAL PROCESS
EXTRACTOR/ " -TRASH
FEEDER
• EXHAUST STREAM
• PRODUCT STREAM
SYSTEM o,,., OTA MOO I ^ COTTON"! „ - LOW PRESSURE SIDE
-— GIN STANDS SEED COMPONENTS
STORAGE
NO. 1 LINT
CLEANER*
EMISSIONS
(3-02-004-07)
1 I
NO. 2 LINT
CLEANER*
EMISSIONS
MOTE FAN [ •" (3-02-004-35)
___! I MOTE TRASH DEMISSIONS
MOTE P^i FAN "" (3-02-004-36)
CLEANER i
L_^ BALED MOTES
CONDENSER AND EMISSIONS
BALING SYSTEM* (3-02-004-08)
_[__ ^ MASTER EMISSIONS
TRASH FAN (3-02-004-03)
BALE STORAGE 1 j »• SOLID WASTE
""CYCLONE'1
ROBBER - EMISSIONS
SYSTEM (3-02-004-30)
Figure 9.7-1. Flow diagram of cotton ginning process.
(Source Classification Codes in parentheses.)
6/96
Food And Agricultural Industry
9.7-3
-------
9.7.2.5 Battery Condenser And Baling System -
Lint cotton is pneumatically transported from the lint cleaning system to a battery condenser,
which is a drum covered with fine mesh screen or fine perforated metal that separates the lint cotton
from the conveying air. The lint cotton is formed into batts and fed into a baling press, which
compresses the cotton into uniform bales.
Most gins use a double-press box for packaging the cotton into bales. The lint drops into one
press box and fills it while a bale is being pressed and strapped in the other box. Approximately
480 Ib (217 kilograms [kg]) of cotton is pressed into a bale before it is wrapped with a cover and
strapped. Modern gins are presently equipped with higher-tonnage bale presses that produce the more
compact universal density cotton bales. In 1995, 96 percent of the U.S. crop was pressed into
universal density bales at the gins. The finished cotton bale is transported to the textile mill for
processing into yarn. Motes are sometimes cleaned and baled also.
9.7.3 Emissions And Controls1'24
Paniculate matter (PM) is the primary air pollutant emitted from cotton ginning. Available
data indicate that about 37 percent of the total PM emitted (following control systems) from cotton
ginning is PM less than or equal to 10 microns in aerodynamic diameter (PM-10). The PM is
composed of fly lint, dust, fine leaves, and other trash. Figure 9.7-1 shows the typical PM emission
points in the ginning process. Paniculate matter emissions are typically greater at gins processing
stripper-harvested cotton than at gins processing picker-harvested cotton. Also, PM emissions from
the first cotton harvest at a given facility are typically lower than emissions from subsequent harvests.
Control devices used to control PM emissions from cotton ginning operations include
cyclones, fine screen coverings, and perforated metal drums. Cyclones may be used to control the
sources with high pressure exhaust or all of the operations at a gin. Two types of cyclones that are
used are 2D-2D and 1D-3D cyclones. Both the body and the cone of a 2D-2D cyclone are twice as
long as the cyclone diameter. The body of a 1D-3D cyclone is the same length as the diameter, and
the cone length is three times the diameter. In many cases, 1D-3D cyclones display slightly higher
PM control efficiencies than 2D-2D cyclones.
Screen coverings and perforated drums may be used to control PM emissions from sources
with low-pressure exhaust, including the battery condenser and lint cleaners.
Table 9.7-1 presents PM and PM-10 emission factors for cotton gins controlled primarily by
1D-3D or 2D-2D cyclones. Emission factors for lint cleaners and battery condensers with screened
drums or cages are also presented. Emission factors for total gin emissions are shown for two
different gin configurations. The emission factors for "Total No.l" represent total PM and PM-10
emissions from gins with all exhaust streams controlled by high-efficiency cyclones. The emission
factors for "Total No. 2" represent total PM and PM-10 emissions from gins with screened drums or
cages controlling the lint cleaner and battery condenser exhausts and high-efficiency cyclones
controlling all other exhaust streams. The emission factors for the No. 3 dryer and cleaner, cyclone
robber system, and mote trash fan are not included in either total because these processes are not used
at most cotton gins. However, these factors should be added into the total for a particular gin if these
processes are used at that gin.
9.7-4 EMISSION FACTORS 6/96
-------
Table 9.7-1. EMISSION FACTORS FOR COTTON GINS
CONTROLLED WITH HIGH-EFFICIENCY CYCLONES"
Source
Unloading fan (SCC 3-02-004-01)
No. 1 dryer and cleaner (SCC 3-02-004-20)
No. 2 dryer and cleaner (SCC 3-02-004-21)
No. 3 dryer and cleaner" (SCC 3-02-004-22)
Overflow fan1 (SCC 3-02-004-25)
Lint cleaners (SCC 3-02-004-07)
with high-efficiency cyclonesk
with screened drums or cages™
Cyclone robber system" (SCC 3-02-004-30)
Mote fan (SCC 3-02-004-35)
Mote trash fanr (SCC 3-02-004-36)
Battery condenser (SCC 3-02-004-08)
with high-efficiency cyclones*
with screened drums or cages01
Master trash fan (SCC 3-02-004-03)
Cotton gin total No. lv (SCC 3-02-004-10)
Cotton gin total No. 2W (SCC 3-02-004-10)
Total PM,
Ib/bale
0.29"
0.36"
0.24f
0.095
0.071
0.58
1.1
0.18
0.28"
0.077
0.039
0.17
0.54*
2.4
3.1
EMISSION
FACTOR
RATING
D
D
D
D
D
D
E
D
D
D
D
E
D
D
E
PM-10,
Ib/bale
0.12°
0.12e
0.0938
0.033
0.026
0.24
ND
0.052
0.13"
0.021
0.014
ND
0.074"
0.82
1.2
EMISSION
FACTOR
RATING
D
D
D
D
D
D
NA
D
D
D
D
NA
D
D
E
Emission factor units are Ib of pollutant per bale of cotton processed. Emissions are controlled
by 1D-3D or 2D-2D high-efficiency cyclones unless noted. SCC = source classification code.
ND = no data available. To convert from Ib/bale to kg/bale, multiply by 0.45.
References 13-15,17,19-20,22,24.
References 13-14,17,22,24.
References 12-14,17,19,21.
References 12-14,17,21.
References 9,12,14,17,19,24.
References 9,12,14,17,24.
References 10,16. Most gins do not include this source, and these emission factors are not
included in the total gin emission factors shown. However, these factors should be added into
the total for a particular gin if this source is part of that gin.
References 10,14,17,24.
References 13-14,17,21-23. Emission factors are included in Total No. 1, but are not included
in Total No. 2.
References 18-20. Emission factors are not included in Total No. 1, but are included in Total
No. 2.
Reference 22. Most gins do not include this source, and these emission factors are not included
in the total gin emission factors shown. However, these factors should be added into the total for
a particular gin if this source is part of that gin.
References 11-14,17,19-20,23-24.
References 11-14,17,24.
References 10-11,22. Many gins do not include this source, and these emission factors are not
included in the total gin emission factors shown. However, these factors should be added into
the total for a particular gin if these sources are part of that gin.
References 14,16-17,23-24. Emission factors are included in Total No. 1, but are not included
in Total No. 2.
References 15,19,22.
6/96
Food And Agricultural Industry
9.7-5
-------
Table 9.7-1 (cont.).
u References 15,22.
v Total for gins with high-efficiency cyclones on all exhaust streams. Does not include emission
factors for the No. 3 dryer and cleaner, cyclone robber system, mote trash fan, lint cleaners with
screened drums or cages, and battery condenser with screened drums or cages.
w Total for gins with screened drums or cages on the lint cleaners and battery condenser and high-
efficiency cyclones on all other exhaust streams. Does not include emission factors for the No. 3
dryer and cleaner, cyclone robber system, mote trash fan, lint cleaners with high-efficiency
cyclones, and battery condenser with high-efficiency cyclones. PM-10 emissions from lint
cleaners and battery condensers with screened drums or cages are estimated as 50 percent of the
total PM emissions from these sources.
9.7.4 Summary of Terminology
Bale — A compressed and bound package of cotton lint, typically weighing about 480 Ib.
Batt — Matted lint cotton.
Boll — The capsule or pod of the cotton plant.
Bur (or burr) — The rough casing of the boll. Often referred to as hulls after separation from
the cotton.
Condenser — A perforated or screened drum device designed to collect lint cotton from the
conveying airstream, at times into a batt.
Cotton — General term used variously to refer to the cotton plant (genus Gossypiuni);
agricultural crop; harvest product; white fibers (lint) ginned (separated) from the seed; baled produce;
and yarn or fabric products. Cotton is classified as upland or extra long staple depending on fiber
length.
Cottonseed — The seed of the cotton plant, separated from its fibers. The seeds constitute
40 percent to 55 percent of the seed cotton (depending on the amount of trash) and are processed into
oil meal, linters, and hulls, or are fed directly to cattle.
Cyclone — A centrifugal air pollution control device for separating solid particles from an
airstream.
Cyclone robber system - A secondary cyclone trash handling system. These systems are not
used at most cotton gins.
Cylinder cleaner — A machine with rotating spiked drums that open the locks and clean the
cotton by removing dirt and small trash.
Extractor — Equipment for removing large trash pieces (sticks, stems, burs, and leaves). The
equipment may include one or more devices, including a stick machine, bur machine, green-leaf
machine, and a combination machine.
Extractor-feeder — A device that gives seed cotton a final light extraction/cleaning and then
feeds it at a controlled rate to the gin stand.
Fly lint (or lint fly) — Short (less than 50 pm) cotton fibers, usually emitted from condensers
and mote fan.
9.7-6 EMISSION FACTORS 6/96
-------
Gin stand — The heart of the ginning plant where gin saws (usually several in parallel)
separate the cotton lint from the seeds.
High pressure side — The portion of the process preceding the gin stand (including unloading,
drying, extracting, cleaning, and overflow handling systems) in which material is conveyed by a
higher pressure air, and exhausts are typically controlled by cyclones.
Lint cleaner — A machine for removing foreign material from lint cotton.
Lint cotton — Cotton fibers from which the trash and seeds have been removed by the gin.
Low pressure side — The portion of the process following the gin stand (including lint cotton
cleaning and batt formation process) in which material is conveyed by low pressure air, and exhausts
are typically controlled by condensers.
Mote — A small group of short fibers attached to a piece of the seed or to an immature seed.
Motes may be cleaned and baled.
Picker harvester — A machine that removes cotton lint and seeds from open bolls with
rotating spindles, leaving unopened bolls on the plant. "First pick" cotton is obtained from the initial
harvest of the season. It usually contains less trash than "second pick" cotton, obtained later in the
harvest season. "Ground cotton" is obtained by picking up between the rows at season's end and has
a high trash content.
Seed cotton — Raw cotton, containing lint, seed, and some waste material, as it comes from
the field.
Separator — A mechanical device (e.g., wire screen with rotary rake) that separates seed
cotton from conveying air.
Stripper harvester — A machine that strips all bolls — opened (mature) and unopened
(immature or green) — from the plant; strippers are used on short cotton plants, grown in arid areas
of Texas, Oklahoma, and New Mexico. They collect larger amounts of trash (leaves, stems, and
sticks) than picker harvesters.
References For Section 9.7
1. Airborne Paniculate Emissions From Cotton Ginning Operations, A60-5, U. S. Department
Of Health, Education And Welfare, Cincinnati, OH, 1960.
2. Source Assessment: Cotton Gins, EPA-600/2-78-004a, U. S. Environmental Protection
Agency, Cincinnati, OH, January 1978.
3. A. C. Griffin And E. P. Columbus, Dust In Cotton Gins: An Overview, U. S. Cotton
Ginning Laboratory, Stoneville, MS, 1982.
4. W. J. Roddy, "Controlling Cotton Gin Emissions", Journal Of The Air Pollution Control
Association, 2S(6):637, June 1978.
5. Written Communication From Phillip J. Wakelyn And Fred Johnson, National Cotton Council
Of America, Washington, DC, To David Reisdorph, Midwest Research Institute, Kansas
City, MO, December 30, 1992.
6. Cotton Ginners Handbook, Agricultural Handbook No. 503, Agricultural Research Service,
U. S. Department Of Agriculture, 1977, U.S. Government Printing Office, Stock
No. 001-000-03678-5.
6/96 Food And Agricultural Industry 9.7-7
-------
7. Written Communication From Fred Johnson And Phillip J. Wakelyn, National Cotton Council
Of America, Memphis, TN, To Dallas Safriet, U. S. Environmental Protection Agency,
Research Triangle Park, NC, October 31, 1995.
8. Emission Factor Documentation, AP-42 Section 9.7, Cotton Ginning, EPA Contract
No. 68-D2-0159, Midwest Research Institute, Gary, NC, June 1996.
9. Westfield Gin-PMW & Total Paniculate Testing-Main Trash Stock Piler Cyclone, #2 Incline
Cyclone, Gin Feed Trash Cyclone, ETC Environmental, Inc., Ventura, CA, November 14-15,
1991.
10. Airways Gin-PMW & Total Paniculate Testing-Motes Trash Cyclone, #3 Incline Cyclone,
Overflow Separator Cyclone, BTC Environmental, Inc., Ventura, CA, November 21-22,
1991.
11. Source Emission Testing-Mount Whitney Cotton Gin, BTC Environmental, Inc., Ventura,
CA, November 29-30, 1990.
12. Source Emission Testing—Stratford Growers, BTC Environmental, Inc., Ventura, CA,
November 27-28, 1990.
13. Source Emission Testing—County Line Gin, BTC Environmental, Inc., Ventura, CA,
December 3-4, 1990.
14. County Line Gin—PMlO & Total Paniculate Testing—Motes, Suction, Lint Cleaner, Overflow,
#1 Drying, Gin Stand Trash, Battery Condenser, And #2 Drying Cyclones, BTC
Environmental, Inc., Ventura, CA, December 8-11, 1991.
15. Westfield Gin-PMW & Total Paniculate Testing-Trash Cyclone, BTC Environmental, Inc.,
Ventura, CA, November 12, 1992.
16. West Valley Cotton Growers-PMW & Total Paniculate Testing-Battery Condenser And #3
Dryer/Cleaner Cyclones, BTC Environmental, Inc., Ventura, CA, October 28, 1993.
17. Dos Palos Cooperative-PMW & Total Paniculate Testing-Motes, Suction, Lint Cleaner,
Overflow, #/ Drying, Battery Condenser, And #2 Drying Cyclones, BTC Environmental, Inc.,
Ventura, CA, November 27-29, 1992.
18. Halls Gin Company-Paniculate Emissions From Cotton Gin Exhausts, State Of Tennessee
Department Of Health And Environment Division Of Air Pollution Control, Nashville, TN,
October 25-27, 1988.
19. Cotton Gin Emission Tests, Marana Gin, Producers Cotton Oil Company, Marana, Arizona,
EPA-330/2-78-008, National Enforcement Investigations Center, Denver, CO, And
EPA Region IX, San Francisco, CA, May 1978.
20. Emission Test Report, Westside Farmers' Cooperative Gin #5, Tranquility, California,
Prepared For U. S. Environmental Protection Agency Division Of Stationary Source
Enforcement, Washington, D.C., PEDCo Environmental, Inc., Cincinnati, OH,
February 1978.
21. Elbow Enterprises-PM-W And Total Paniculate Testing, Lint Cleaner And Dryer #7
Cyclones, AIRx Testing, Ventura, CA, November 7-8, 1994.
9.7-8 EMISSION FACTORS 6/96
-------
22. Stratford Growers, Inc.-PM-lO And Total Paniculate Testing, Unloading, Hull Trash, Feeder
Trash, Lint Cleaner, Cyclone Robber System, & Motes Trash Cyclones, AIRx Testing,
Ventura, CA, October 26-28, 1994.
23. Alta Vista Gin-PM-10 And Total Paniculate Testing, Battery Condenser, Lint Cleaner, &
Motes Trash Cyclones, AIRx Testing, Ventura, CA, November 3-4, 1994.
24. Dos Palos Coop Gin—PM-10 And Total Paniculate Testing, Unloading, Dryer #2, Overflow,
Battery Condenser, & Motes Cyclones, AIRx Testing, Ventura, CA, October 31 Through
November 2, 1994.
6/96 Food And Agricultural Industry 9.7-9
-------
9.8.1 Canned Fruits And Vegetables
9.8.1.1 General1-2
The canning of fruits and vegetables is a growing, competitive industry, especially the
international export portion. The industry is made up of establishments primarily engaged in canning
fruits, vegetables, fruit and vegetable juices; processing ketchup and other tomato sauces; and
producing natural and imitation preserves, jams, and jellies.
9.8.1.2 Process Description3'6
The primary objective of food processing is the preservation of perishable foods in a stable
form that can be stored and shipped to distant markets during all months of the year. Processing also
can change foods into new or more usable forms and make foods more convenient to prepare.
The goal of the canning process is to destroy any microorganisms in the food and prevent
recontamination by microorganisms. Heat is the most common agent used to destroy
microorganisms. Removal of oxygen can be used in conjunction with other methods to prevent the
growth of oxygen-requiring microorganisms.
In the conventional canning of fruits and vegetables, there are basic process steps that are
similar for both types of products. However, there is a great diversity among all plants and even
those plants processing the same commodity. The differences include the inclusion of certain
operations for some fruits or vegetables, the sequence of the process steps used in the operations, and
the cooking or blanching steps. Production of fruit or vegetable juices occurs by a different sequence
of operations and there is a wide diversity among these plants. Typical canned products include beans
(cut and whole), beets, carrots, corn, peas, spinach, tomatoes, apples, peaches, pineapple, pears,
apricots, and cranberries. Typical juices are orange, pineapple, grapefruit, tomato, and cranberry.
Generic process flow diagrams for the canning of fruits, vegetables, and fruit juices are shown in
Figures 9.8.1-1, 9.8.1-2, and 9.8.1-3. The steps outlined in these figures are intended to the basic
processes in production. A typical commercial canning operation may employ the following general
processes: washing, sorting/grading, preparation, container filling, exhausting, container sealing, heat
sterilization, cooling, labeling/casing, and storage for shipment. In these diagrams, no attempt has
been made to be product specific and include all process steps that would be used for all products.
Figures 9.8.1-1 and 9.8.1-2 show optional operations, as dotted line steps, that are often used but are
not used for all products. One of the major differences in the sequence of operations between fruit
and vegetable canning is the blanching operation. Most of the fruits are not blanched prior to can
filling whereas many of the vegetables undergo this step. Canned vegetables generally require more
severe processing than do fruits because the vegetables have much lower acidity and contain more
heat-resistant soil organisms. Many vegetables also require more cooking than fruits to develop their
most desirable flavor and texture. The methods used in the cooking step vary widely among
facilities. With many fruits, preliminary treatment steps (e. g., peeling, coring, halving, pitting)
occur prior to any heating or cooking step but with vegetables, these treatment steps often occur after
the vegetable has been blanched. For both fruits and vegetables, peeling is done either by a
mechanical peeler, steam peeling, or lye peeling. The choice depends upon the type of fruit or
vegetable or the choice of the company.
8/95 Food And Agricultural Industry 9.8.1-1
-------
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-------
Some citrus fruit processors produce dry citrus peel, citrus molasses and D-limonene from the
peels and pulp residue collected from the canning and juice operations. Other juice processing
facilities use concentrates and raw commodity processing does not occur at the facility. The peels and
residue are collected and ground in a hammermill, lime is added to neutralize the acids, and the
product pressed to remove excess moisture. The liquid from the press is screened to remove large
particles, which are recycled back to the press, and the liquid is concentrated to molasses in an
evaporator. The pressed peel is sent to a direct-fired hot-air drier. After passing through a condenser
to remove the D-limonene, the exhaust gases from the drier are used as the heat source for the
molasses evaporator.
Equipment for conventional canning has been converting from batch to continuous units. In
continuous retorts, the cans are fed through an air lock, then rotated through the pressurized heating
chamber, and subsequently cooled through a second section of the retort in a separate cold-water
cooler. Commercial methods for sterilization of canned foods with a pH of 4.5 or lower include use
of static retorts, which are similar to large pressure cookers. A newer unit is the agitating retort,
which mechanically moves the can and the food, providing quicker heat penetration. In the aseptic
packaging process, the problem with slow heat penetration in the in-container process are avoided by
sterilizing and cooling the food separate from the container. Presterilized containers are then filled
with the sterilized and cooled product and are sealed in a sterile atmosphere.
To provide a closer insight into the actual processes that occur during a canning operation, a
description of the canning of whole tomatoes is presented in the following paragraphs. This
description provides more detail for each of the operations than is presented in the generic process
flow diagrams in Figures 9.8.1-1, 9.8.1-2, and 9.8.1-3.
Preparation -
The principal preparation steps are washing and sorting. Mechanically harvested tomatoes are
usually thoroughly washed by high-pressure sprays or by strong-flowing streams of water while being
passed along a moving belt or on agitating or revolving screens. The raw produce may need to be
sorted for size and maturity. Sorting for size is accomplished by passing the raw tomatoes through a
series of moving screens with different mesh sizes or over differently spaced rollers. Separation into
groups according to degree of ripeness or perfection of shape is done by hand; trimming is also done
by hand.
Peeling And Coring -
Formerly, tomatoes were initially scalded followed by hand peeling, but steam peeling and lye
peeling have also become widely used. With steam peeling, the tomatoes are treated with steam to
loosen the skin, which is then removed by mechanical means. In lye peeling, the fruit is immersed in
a hot lye bath or sprayed with a boiling solution of 10 to 20 percent lye. The excess lye is then
drained and any lye that adheres to the tomatoes is removed with the peel by thorough washing.
Coring is done by a water-powered device with a small turbine wheel. A special blade
mounted on the turbine wheel spins and removes the tomato cores.
Filling -
After peeling and coring, the tomatoes are conveyed by automatic runways, through washers,
to the point of filling. Before being filled, the can or glass containers are cleaned by hot water,
steam, or air blast. Most filling is done by machine. The containers are filled with the solid product
and then usually topped with a light puree of tomato juice. Acidification of canned whole tomatoes
with 0.1 to 0.2 percent citric acid has been suggested as a means of increasing acidity to a safer and
8/95 Food And Agricultural Industry 9.8.1-5
-------
more desirable level. Because of the increased sourness of the acidified product, the addition of 2 to
3 percent sucrose is used to balance the taste. The addition of salt is important for palatability.
Exhausting -
The objective of exhausting containers is to remove air so that the pressure inside the
container following heat treatment and cooling will be less than atmospheric. The reduced internal
pressure (vacuum) helps to keep the can ends drawn in, reduces strain on the containers during
processing, and minimizes the level of oxygen remaining in the headspace. It also helps to extend the
shelf life of food products and prevents bulging of the container at high altitudes.
Vacuum in the can may be obtained by the use of heat or by mechanical means. The
tomatoes may be preheated before filling and sealed hot. For products that cannot be preheated
before filling, it may be necessary to pass the filled containers through a steam chamber or tunnel
prior to the sealing machine to expel gases from the food and raise the temperature. Vacuum also
may be produced mechanically by sealing containers in a chamber under a high vacuum.
Sealing -
In sealing lids on metal cans, a double seam is created by interlocking the curl of the lid and
flange of the can. Many closing machines are equipped to create vacuum in the headspace either
mechanically or by steam-flow before lids are sealed.
Heat Sterilization -
During processing, microorganisms that can cause spoilage are destroyed by heat. The
temperature and processing time vary with the nature of the product and the size of the container.
Acidic products, such as tomatoes, are readily preserved at 100°C (212°F). The containers
holding these products are processed in atmospheric steam or hot-water cookers. The rotary
continuous cookers, which operate at 100°C (212°F), have largely replaced retorts and open-still
cookers for processing canned tomatoes. Some plants use hydrostatic cookers and others use
continuous-pressure cookers.
Cooling -
After heat sterilization, containers are quickly cooled to prevent overcooking. Containers may
be quick cooled by adding water to the cooker under air pressure or by conveying the containers from
the cooker to a rotary cooler equipped with a cold-water spray.
Labeling And Casing -
After the heat sterilization, cooling, and drying operations, the containers are ready for
labeling. Labeling machines apply glue and labels in one high-speed operation. The labeled cans or
jars are the packed into shipping cartons.
9.8.1.3 Emissions And Controls4-6"9
Air emissions may arise from a variety of sources in the canning of fruits and vegetables.
Particulate matter (PM) emissions result mainly from solids handling, solids size reduction, drying
(e. g., citrus peel driers). Some of the particles are dusts, but others (particularly those from thermal
processing operations) are produced by condensation of vapors and may be in the low-micrometer or
submicrometer particle-size range.
9.8.1-6 EMISSION FACTORS 8/95
-------
The VOC emissions may potentially occur at almost any stage of processing, but most usually
are associated with thermal processing steps, such as cooking, and evaporative concentration. The
cooking technologies in canning processes are very high moisture processes so the predominant
emissions will be steam or water vapor. The waste gases from these operations may contain PM or,
perhaps, condensable vapors, as well as malodorous VOC. Particulate matter, condensable materials,
and the high moisture content of the emissions may interfere with the collection or destruction of
these VOC. The condensable materials also may be malodorous.
Wastewater treatment ponds may be another source of odors, even from processing of
materials that are not otherwise particularly objectionable. Details on the processes and technologies
used in waste water collection, treatment, and storage are presented in AP-42 Section 4.3; that section
should be consulted for detailed information on the subject.
No emission data quantifying VOC, HAP, or PM emissions from the canned fruits and
vegetable industry are available for use in the development of emission factors. Data on emissions
from fruit and vegetable canning are extremely limited. Woodroof and Luh discussed the presence of
VOC in apricots, cranberry juice, and cherry juice. Van Langenhove, et al., identified volatile
compounds emitted during the blanching process of Brussels sprouts and cauliflower under laboratory
and industrial conditions. Buttery, et al., studied emissions of volatile aroma compounds from tomato
paste.
A number of emission control approaches are potentially available to the canning industry.
These include wet scrubbers, dry sorbants, and cyclones. No information is available on controls
actually used at canning facilities.
Control of VOC from a gas stream can be accomplished using one of several techniques but
the most common methods are absorption, adsorption, and afterburners. Absorptive methods
encompass all types of wet scrubbers using aqueous solutions to absorb the VOC. Most scrubber
systems require a mist eliminator downstream of the scrubber.
Adsorptive methods could include one of four main adsorbents: activated carbon, activated
alumina, silica gel, or molecular sieves. Of these four, activated carbon is the most widely used for
VOC control while the remaining three are used for applications other than pollution control. Gas
adsorption is a relatively expensive technique and may not be applicable to a wide variety of
pollutants.
Particulate control commonly employs methods such as venturi scrubbers, dry cyclones, wet
or dry electrostatic precipitators (ESPs), or dry filter systems. The most common controls are likely
to be the venturi scrubbers or dry cyclones. Wet or dry ESPs could be used depending upon the
particulate loading of the gas stream.
Condensation methods and scrubbing by chemical reaction may be applicable techniques
depending upon the type of emissions. Condensation methods may be either direct contact or indirect
contact with the shell and tube indirect method being the most common technique. Chemical reactive
scrubbing may be used for odor control in selective applications.
8/95 Food And Agricultural Industry 9.8.1-7
-------
References for Section 9.8.1
1. U. S. Department of Commerce, International Trade Administration, U. S. Industrial Outlook
1992-Food and Beverages.
2. 1987 Census of Manufacturers, MC87-1-20-C, Industries Series, Preserved Fruits and
Vegetables.
3. B. S. Luh and J. G. Woodroof, ed., Commercial Vegetable Processing, 2nd edition, Van
Nostrand Reinhold, New York, 1988.
4. J. L. Jones, et al., Overview Of Environmental Control Measures And Problems In The Food
Processing Industries. Industrial Environmental Research Laboratory, Cincinnati, OH,
Kenneth Dostal, Food and Wood Products Branch. Grant No. R804642-01, January 1979.
5. N. W. Deroiser, The Technology Of Food Preservation, 3rd edition, The Avi Publishing
Company, Inc., Westport, CT, 1970.
6. J. G. Woodroof and B. S. Luh, ed., Commercial Fruit Processing, The Avi Publishing
Company, Westport, CT, 1986.
7. H. J. Van Langenhove, et al., Identification Of Volatiles Emitted During The Blanching
Process Of Brussels Sprouts And Cauliflower, Journal of the Science of Food and Agriculture,
55:483-487, 1991.
8. R. G. Buttery, et al., Identification Of Additional Tomato Paste Volatiles, Journal of
Agricultural and Food Chemistry, 38(3):792-795, 1990.
9. H. J. Rafson, Odor Emission Control For The Food Industry, Food Technology, June 1977.
9.8.1-8 EMISSION FACTORS 8/95
-------
9.8.2 Dehydrated Fruits And Vegetables
9.8.2.1 General1'2
Dehydration of fruit and vegetables is one of the oldest forms of food preservation techniques
known to man and consists primarily of establishments engaged in sun drying or artificially
dehydrating fruits and vegetables. Although food preservation is the primary reason for dehydration,
dehydration of fruits and vegetables also lowers the cost of packaging, storing, and transportation by
reducing both the weight and volume of the final product. Given the improvement in the quality of
dehydrated foods, along with the increased focus on instant and convenience foods, the potential of
dehydrated fruits and vegetables is greater than ever.
9.8.2.2 Process Description1'2
Dried or dehydrated fruits and vegetables can be produced by a variety of processes. These
processes differ primarily by the type of drying method used, which depends on the type of food and
the type of characteristics of the final product. In general, dried or dehydrated fruits and vegetables
undergo the following process steps: predrying treatments, such as size selection, peeling, and color
preservation; drying or dehydration, using natural or artificial methods; and postdehydration
treatments, such as sweating, inspection, and packaging.
Predrying Treatments -
Predrying treatments prepare the raw product for drying or dehydration and include raw
product preparation and color preservation. Raw product preparation includes selection and sorting,
washing, peeling (some fruits and vegetables), cutting into the appropriate form, and blanching (for
some fruits and most vegetables). Fruits and vegetables are selected; sorted according to size,
maturity, and soundness; and then washed to remove dust, dirt, insect matter, mold spores, plant
parts, and other material that might contaminate or affect the color, aroma, or flavor of the fruit or
vegetable. Peeling or removal of any undesirable parts follows washing. The raw product can be
peeled by hand (generally not used in the United States due to high labor costs), with lye or alkali
solution, with dry caustic and mild abrasion, with steam pressure, with high-pressure washers, or
with flame peelers. For fruits, only apples, pears, bananas, and pineapples are usually peeled before
dehydration. Vegetables normally peeled include beets, carrots, parsnips, potatoes, onions, and
garlic. Prunes and grapes are dipped in an alkali solution to remove the natural waxy surface coating
which enhances the drying process. Next, the product is cut into the appropriate shape or form (i. e.,
halves, wedges, slices, cubes, nuggets, etc.), although some items, such as cherries and corn, may
by-pass this operation. Some fruits and vegetables are blanched by immersion in hot water (95° to
100°C [203° to 212°F]) or exposure to steam.
The final step in the predehydration treatment is color preservation, also known as sulfuring.
The majority of fruits are treated with sulfur dioxide (SO2) for its antioxidant and preservative effects.
The presence of SO2 is very effective in retarding the browning of fruits, which occurs when the
enzymes are not inactivated by the sufficiently high heat normally used in drying. In addition to
preventing browning, SO2 treatment reduces the destruction of carotene and ascorbic acid, which are
the important nutrients for fruits. Sulfuring dried fruits must be closely controlled so that enough
sulfur is present to maintain the physical and nutritional properties of the product throughout its
expected shelf life, but not so large that it adversely affects flavor. Some fruits, such as apples, are
treated with solutions of sulfite (sodium sulfite and sodium bisulfite in approximately equal
9/95 Food And Agricultural Industry 9.8.2-1
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proportions) before dehydration. Sulfite solutions are less suitable for fruits than burning sulfur (SO2
gas), however, because the solution penetrates the fruit poorly and can leach natural sugar, flavor,
and other components from the fruit.
Although dried fruits commonly use SO2 gas to prevent browning, this treatment is not
practical for vegetables. Instead, most vegetables (potatoes, cabbage, and carrots) are treated with
sulfite solutions to retard enzymatic browning. In addition to color preservation, the presence of a
small amount of sulfite in blanched, cut vegetables improves storage stability and makes it possible to
increase the drying temperature during dehydration, thus decreasing drying time and increasing the
drier capacity without exceeding the tolerance for heat damage.
Drying Or Dehydration -
Drying or dehydration is the removal of the majority of water contained in the fruit or
vegetable and is the primary stage in the production of dehydrated fruits and vegetables. Several
drying methods are commercially available and the selection of the optimal method is determined by
quality requirements, raw material characteristics, and economic factors. There are three types of
drying processes: sun and solar drying; atmospheric dehydration including stationary or batch
processes (kiln, tower, and cabinet driers) and continuous processes (tunnel, continuous belt, belt-
trough, fluidized-bed, explosion puffing, foam-mat, spray, drum, and microwave-heated driers); and
subatmospheric dehydration (vacuum shelf, vacuum belt, vacuum drum, and freeze driers).
Sun drying (used almost exclusively for fruit) and solar drying (used for fruit and vegetables)
of foods use the power of the sun to remove the moisture from the product. Sun drying of fruit crops
is limited to climates with hot sun and dry atmosphere, and to certain fruits, such as prunes, grapes,
dates, figs, apricots, and pears. These crops are processed in substantial quantities without much
technical aid by simply spreading the fruit on the ground, racks, trays, or roofs and exposing them to
the sun until dry. Advantages of this process are its simplicity and its small capital investment.
Disadvantages include complete dependence on the elements and moisture levels no lower than 15 to
20 percent (corresponding to a limited shelf life). Solar drying utilizes black-painted trays, solar
trays, collectors, and mirrors to increase solar energy and accelerate drying.
Atmospheric forced-air driers artificially dry fruits and vegetables by passing heated air with
controlled relative humidity over the food to be dried, or by passing the food to be dried through the
heated air, and is the most widely used method of fruit and vegetable dehydration. Various devices
are used to control air circulation and recirculation. Stationary or batch processes include kiln, tower
(or stack), and cabinet driers. Continuous processes are used mainly for vegetable dehydration and
include tunnel, continuous belt, belt-trough, fluidized-bed, explosion puffing, foam-mat, spray, drum,
and microwave-heated driers. Tunnel driers are the most flexible, efficient, and widely used
dehydration system available commercially.
Subatmospheric (or vacuum) dehydration occurs at low air pressures and includes vacuum
shelf, vacuum drum, vacuum belt, and freeze driers. The main purpose of vacuum drying is to
enable the removal of moisture at less than the boiling point under ambient conditions. Because of
the high installation and operating costs of vacuum driers, this process is used for drying raw material
that may deteriorate as a result of oxidation or may be modified chemically as a result of exposure to
air at elevated temperatures. There are two categories of vacuum driers. In the first category,
moisture in the food is evaporated from the liquid to the vapor stage, and includes vacuum shelf,
vacuum drum, and vacuum belt driers. In the second category of vacuum driers, the moisture of the
food is removed from the product by sublimination, which is converting ice directly into water vapor.
The advantages of freeze drying are high flavor retention, maximum retention of nutritional value,
9.8.2-2 EMISSION FACTORS 9/95
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minimal damage to the product texture and structure, little change in product shape and color, and a
finished product with an open structure that allows fast and complete rehydration. Disadvantages
include high capital investment, high processing costs, and the need for special packing to avoid
oxidation and moisture gain in the finished product.
Postdehydration Treatments -
Treatments of the dehydrated product vary according to the type of fruit or vegetable and the
intended use of the product. These treatments may include sweating, screening, inspection,
instantization treatments, and packaging. Sweating involves holding the dehydrated product in bins
or boxes to equalize the moisture content. Screening removes dehydrated pieces of unwanted size,
usually called "fines". The dried product is inspected to remove foreign materials, discolored pieces,
or other imperfections such as skin, carpel, or stem particles. Instantization treatments are used to
improve the rehydration rate of the low-moisture product. Packaging is common to most all
dehydrated products and has a great deal of influence on the shelf life of the dried product.
Packaging of dehydrated fruits and vegetables must protect the product against moisture, light, air,
dust, microflora, foreign odor, insects, and rodents; provide strength and stability to maintain original
product size, shape, and appearance throughout storage, handling, and marketing; and consist of
materials that are approved for contact with food. Cost is also an important factor in packaging.
Package types include cans, plastic bags, drums, bins, and cartons, and depend on the end-use of the
product.
9.8.2.3 Emissions And Controls1-3"6
Air emissions may arise from a variety of sources in the dehydration of fruits and vegetables.
Particulate matter (PM) emissions may result mainly from solids handling, solids size reduction, and
drying. Some of the particles are dusts, but other are produced by condensation of vapors and may
be in the low-micrometer or submicrometer particle-size range.
The VOC emissions may potentially occur at almost any stage of processing, but most usually
are associated with thermal processing steps, such as blanching, drying or dehydration, and sweating.
Particulate matter and condensable materials may interfere with the collection or destruction of these
VOC. The condensable materials also may be malodorous. The color preservation (sulfuring) stage
can produce SO2 emissions as the fruits and vegetables are treated with SO2 gas or sulfide solution to
prevent discoloration or browning.
Wastewater treatment ponds may be another source of VOC, even from processing of
materials that are not otherwise particularly objectionable. Details on the processes and technologies
used in wastewater collection, treatment, and storage are presented in AP-42 Section 4.3. That
section should be consulted for detailed information on the subject.
No emission data quantifying VOC, HAP, or PM emissions from the dehydrated fruit and
vegetable industry are available for use in the development of emission factors. However, some data
have been published on VOC emitted during the blanching process for two vegetables and for
volatiles from fresh tomatoes. Van Langenhove, et al., identified volatiles emitted during the
blanching process of Brussels sprouts and cauliflower under laboratory and industrial conditions. In
addition, Buttery, et al., performed a quantitative study on aroma volatiles emitted from fresh
tomatoes.
A number of VOC and paniculate emission control techniques are available to the dehydrated
fruit and vegetable industry. No information is available on the actual usage of emission control
9/95 Food And Agricultural Industry 9.8.2-3
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devices in this industry. Potential options include the traditional approaches of wet scrubbers, dry
sorbents, and cyclones.
Control of VOC from a gas stream can be accomplished using one of several techniques but
the most common methods are absorption and adsorption. Absorptive methods encompass all types of
wet scrubbers using aqueous solutions to absorb the VOC. Most scrubber systems require a mist
eliminator downstream of the scrubber.
Adsorptive methods could include one of four main adsorbents: activated carbon, activated
alumina, silica gel, or molecular sieves. Of these four, activated carbon is the most widely used for
VOC control while the remaining three are used for applications other than pollution control. Gas
adsorption is a relatively expensive technique and may not be applicable to a wide variety of
pollutants.
Particulate control commonly employs methods such as venturi scrubbers, dry cyclones, wet
or dry electrostatic precipitators (ESPs), or dry filter systems. The most common controls are likely
to be the venturi scrubbers or dry cyclones. Wet or dry ESPs could be used depending upon the
particulate loading of the gas stream.
Condensation methods and scrubbing by chemical reaction may be applicable techniques
depending upon the type of emissions. Condensation methods may be either direct contact or indirect
contact with the shell and tube indirect method being the most common technique. Chemical reactive
scrubbing may be used for odor control in selective applications.
References For Section 9.8.2
1. L. P. Somogyi and B. S. Luh, "Dehydration Of Fruits", Commercial Fruit
Processing, Second Ed., J. G. Woodroof and B. S. Luh, Editors. AVI Publishing
Company, Inc., 1986.
2. L. P. Somogyi and B. S. Luh, "Vegetable Dehydration", Commercial Vegetable
Processing, Second Ed., B. S. Luh and J. G. Woodroof, Editors, An AVI Book
Published by Van Nostrand Reinhold, 1988.
3. J. L. Jones, et al, "Overview Of Environmental Control Measures And Problems In The
Food Processing Industries", Industrial Environmental Research Laboratory, Cincinnati, OH,
K. Dostal, Food and Wood Products Branch, Grant No. R804642-01, January 1979.
4. H. J. Van Langenhove, et al., "Identification Of Volatiles Emitted During The Blanching
Process Of Brussels Sprouts And Cauliflower", Journal Of The Science Of Food And
Agriculture, 55:483-487, 1991.
5. R. G. Buttery, et al., "Fresh Tomato Aroma Volatiles: A Quantitative Study", /. Agric.
Food Chem., 35:540-544, 1987.
6. H. J. Rafson, "Odor Emission Control For The Food Industry", Food Technology, June 1977.
9.8.2-4 EMISSION FACTORS 9/95
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9.8.3 Pickles, Sauces, and Salad Dressings
9.8.3.1 General1
This industry includes facilities that produce pickled fruits and vegetables, salad dressings,
relishes, various sauces, and seasonings. The two vegetables that account for the highest production
volume in the U. S. are cucumbers (pickles) and cabbage (sauerkraut). Sauces entail a wide diversity
of products but two of the more common types are Worcestershire sauce and hot pepper sauces.
Salad dressings are generally considered to be products added to and eaten with salads. In 1987,
21,500 thousand people were employed in the industry. California, Georgia, Michigan, and
Pennsylvania are the leading employment States in the industry.
9.8.3.2 Process Description2"3
Pickled Vegetables —
In the U. S., vegetables are pickled commercially using one of two general processes:
brining or direct acidification (with or without pasteurization), or various combinations of these
processes. For sodium chloride brining, fresh vegetables are placed in a salt solution or dry salt is
added to cut or whole vegetables whereupon the vegetables undergo a microbial fermentation process
activated by the lactic acid bacteria, yeasts, and other microorganisms. Direct acidification of fresh
or brined vegetables, through the addition of vinegar, is a major component of commercial pickling.
This process may be accompanied by pasteurization, addition of preservatives, refrigeration, or a
combination of these treatments. While cucumbers, cabbage, and olives constitute the largest volume
of vegetables brined or pickled in the U. S., other vegetables include peppers, onions, beans,
cauliflower, and carrots.
In the United States, the term "pickles" generally refers to pickled cucumbers. Three
methods currently are used to produce pickles from cucumbers: brine stock, fresh pack, and
refrigerated. Smaller quantities are preserved by specialized brining methods to produce pickles for
delicatessens and other special grades of pickles. Pickling cucumbers are harvested and transported to
the processing plants. The cucumbers may be field graded and cooled, if necessitated by the
temperature, prior to transport to the plants.
The brine stock process begins with brining the cucumbers through the addition of salt or a
sodium chloride brining solution. The cucumbers undergo a fermentation process in which lactic acid
is formed. During fermentation, the cucumbers are held in 5 to 8 percent salt; after fermentation, the
salt content is increased weekly in 0.25 to 0.5 percent increments until the final holding strength is 8
to 16 percent salt. The cucumbers, called brine stock, are then graded and cut (optional), before
being desalted by washing in an open tank with water at ambient temperature to obtain the desired salt
level and processed into dill, sour, sweet, or other pickle products. Containers are filled with the cut
or whole pickles, and sugar and vinegars are added. Preservatives are also added if the product is not
pasteurized. The containers are then vacuum sealed and pasteurized (optional) until the temperature
at the center of the cucumbers reaches about 74°C (165°F) for about 15 minutes. The product is then
cooled, and the containers are labeled, packaged, and stored.
The fresh pack process begins with grading of the pickling cucumbers, followed by washing
with water. The cucumbers are then either cut and inspected before packaging, or are sometimes
"blanched" if they are to be packaged whole. The "blanching" consists of rinsing the cucumber with
8/95 Food And Agricultural Industry 9.8.3-1
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warm water to make it more pliable and easier to pack in the container. It is not a true blanching
process. Containers are filled with the cut or whole cucumbers, and then salt, spices, and vinegars
are added. The containers are then vacuum sealed and heated (pasteurized) until the temperature at
the center of the cucumbers reaches about 74°C (165°F) for about 15 minutes. The product is then
cooled, and the containers are labeled, packaged, and stored.
The refrigerated process begins with grading of the pickling cucumbers, followed by washing
with water. The washed cucumbers are packed into containers, and then salt, spices, vinegars, and
preservatives (primarily sodium benzoate) are added. The containers are then vacuum sealed, labeled,
and refrigerated at 34° to 40°F. In this process, the cucumbers are not heat-processed before or after
packing.
In the sauerkraut process the cabbage is harvested, transported to the processing plant,
washed, and prepared for the fermentation by coring, trimming, and shredding. The shredded
cabbage is conveyed to a fermentation tank where salt is added up to a final concentration of 2 to
3 percent (preferably 2.25 percent), by weight. After salt addition, the mixture is allowed to ferment
at ambient temperature in a closed tank. If insufficient salt is added or air is allowed to contact the
surface of the cabbage, yeast and mold will grow on the surface and result in a softening of the final
sauerkraut product. When fermentation is complete, the sauerkraut contains 1.7 to 2.3 percent acid,
as lactic acid. Following fermentation, the sauerkraut is packaged in cans, plastic bags, or glass
containers; cans are the most prevalent method. In the canning process, the sauerkraut, containing
the original or diluted fermentation liquor, is heated to 85° to 88 °C (185° to 190°F) by steam
injection in a thermal screw and then packed into cans. The cans are steam exhausted, sealed, and
cooled. After cooling, the cans are labeled, packed, and stored for shipment. In the plastic bag
process, the sauerkraut, containing the fermentation liquor, is placed in plastic bags and chemical
additives (benzoic acid, sorbic acid, and sodium bisulfite) introduced as preservatives. The bags are
sealed and refrigerated. Small quantities, approximately 10 percent of the production, are packaged
in glass containers, which may be preserved by heating or using chemical additives.
Sauces —
A typical sauce production operation involves the mixture of several ingredients, often
including salts, vinegars, sugar, vegetables, and various spices. The mixture is allowed to ferment
for a period of time, sealed in containers, and pasteurized to prevent further fermentation. The
production processes for Worcestershire sauce and hot pepper sauces are briefly described as
examples of sauce production.
The name "Worcestershire Sauce" is now a generic term for a type of food condiment that
originated in India. In the preparation of the true sauce, a mixture of vinegar, molasses, sugar, soy,
anchovies, tamarinds, eschalots, garlic, onions, and salt is prepared and well mixed. Spices,
flavorings, and water are added and the mixture transferred to an aging tank, sealed, and allowed to
mature and ferment over a period of time. The fermenting mixture is occasionally agitated to ensure
proper blending. After fermentation is complete, the mixture is processed by filtration through a
mesh screen which allows the finer particles of the mixture to remain in the liquid. The product is
then pasteurized prior to bottling to prevent further fermentation. Following bottling, the product is
cooled, labeled, and packaged.
Hot sauce or pepper sauce is a generic name given to a large array of bottled condiments
produced by several manufacturers in the U. S. The hot peppers, usually varieties of Capsicum
annum and Capsicum frutescens, give the products their heat and characteristic flavor; vinegar is the
usual liquid medium. Manufacturing processes vary by producer; however, in most, the harvested
9.8.3-2 EMISSION FACTORS 8/95
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hot peppers are washed and either ground for immediate use or stored whole in brine for several
months until processed. In processing, the whole peppers are ground, salt and vinegar added, and the
mixture passed through a filter to remove seeds and skin. The end-product, a stable suspension of the
pulp from the pepper, vinegar, and salt, is then bottled, labeled, and stored for shipment.
Salad Dressings —
Salad dressings (except products modified in calories, fat, or cholesterol) are typically made
up of oil, vinegar, spices, and other food ingredients to develop the desired taste. These dressings
are added to many types of foods to enhance flavor. There are U. S. FDA Standards of Identity for
three general classifications of salad dressings: mayonnaise, spoonable (semisolid) salad dressing, and
French dressing. All other dressings are nonstandardized and are typically referred to as "pourable".
Mayonnaise is a semisolid emulsion of edible vegetable oil, egg yolk or whole egg, acidifying
ingredients (vinegar, lemon or lime juice), seasonings (e. g., salt, sweeteners, mustard, paprika),
citric acid, malic acid, crystallization inhibitors, and sequestrants to preserve color and flavor.
Mayonnaise is an oil-in-water type emulsion where egg is the emulsifying agent and vinegar and salt
are the principal bacteriological preservatives. The production process begins with mixing water,
egg, and dry ingredients and slowly adding oil while agitating the mixture. Vinegar is then added to
the mixture and, after mixing is complete, containers are filled, capped, labeled, and stored or
shipped. Improved texture and uniformity of the final product is achieved through the use of
colloidalizing or homogenizing machines.
Salad dressing is a spoonable (semisolid) combination of oil, cooked starch paste base, and
other ingredients. During salad dressing production, the starch paste base is prepared by mixing
starch (e. g., food starch, tapioca, wheat or rye flours) with water and vinegar. Optional ingredients
include salt, nutritive carbohydrate sweeteners (e. g., sugar, dextrose, corn syrup, honey), any spice
(except saffron and turneric) or natural flavoring, monosodium glutamate, stabilizers and thickeners,
citric and/or malic acid, sequestrants, and crystallization inhibitors. To prepare the salad dressing, a
portion of the starch paste and other optional ingredients, except the oil, are blended and then the oil
is slowly added to form a "preemulsion". When one-half of the oil is incorporated, the remainder of
the starch paste is added at the same rate as the oil. After all of the starch paste and oil have been
added, the mixture continues to blend until the ingredients are thoroughly mixed and then the mixture
is milled to a uniform consistency. The salad dressing is placed into containers that are subsequently
capped, labeled, and stored or shipped.
Liquid dressings, except French dressing, do not have a FDA Standard of Identity. They are
pourable products that contain vegetable oil as a basic ingredient. Dressings may also contain catsup,
tomato paste, vinegars, cheese, sherry, spices, and other natural ingredients. Liquid dressings are
packaged either as separable products with distinct proportions of oil and aqueous phases or as
homogenized dressings that are produced by the addition of stabilizers and emulsifiers. The
homogenized dressings are then passed through a homogenizer or colloidalizing machine prior to
bottling.
9.8.3.3 Emissions And Controls4
No source tests have been performed to quantify emissions resulting from the production of
pickles, sauerkraut, sauces, or salad dressings. For most of these industries, processes are conducted
in closed tanks or other vessels and would not be expected to produce significant emissions. For
some products, in certain instances, the potential exists for emissions of paniculate matter (PM) or
odor (VOC).
8/95 Food And Agricultural Industry 9.8.3-3
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Emissions of PM potentially could result from solids handling, solids size reduction, and
cooking. If raw vegetables are transported directly from the field, the unloading of these vegetables
could result in emissions of dust or vegetative matter. For those products that involve cooking or
evaporative condensation in open vessels, PM emissions may be produced by condensation of vapors
and may be in the low-micrometer or submicrometer particle-size range.
The VOC emissions are most usually associated with thermal processing steps (e. g., cooking
or evaporative condensation) or other processing steps performed in open vessels. Thermal
processing steps conducted in closed vessels generally do not result in VOC emissions. Gaseous
compounds emitted from those steps conducted in open vessels may contain malodorous VOC.
Because no emission data are available that quantify any VOC, HAP, or PM emissions from
any of these industries, emission factors cannot be developed.
A number of VOC and particulate emission control techniques are potentially available to
these industries. These include the traditional approaches of wet scrubbers, dry sorbants, and
cyclones. No information is available on controls actually used in these industries. The controls
discussed in this section are ones that theoretically could be used. The applicability of controls and
the specific type of control device or combination of devices would vary from facility to facility
depending upon the particular nature of the emissions and the pollutant concentration in the gas
stream.
For general industrial processes, control of VOC from a gas stream can be accomplished
using one of several techniques but the most common methods are absorption, adsorption, and
afterburners. Absorptive methods encompass all types of wet scrubbers using aqueous solutions to
absorb the VOC. The most common scrubber systems are packed columns or beds, plate columns,
spray towers, or other types of towers. Adsorptive methods could include one of four main
adsorbents: activated carbon, activated alumina, silica gel, or molecular sieves; activated carbon is the
most widely used for VOC control. Afterburners may be either thermal incinerators or catalytic
combustors.
Particulate control commonly employs methods such as venturi scrubbers, dry cyclones, wet
or dry electrostatic precipitators (ESPs), or dry filter systems. The most common controls are likely
to be the venturi scrubbers or dry cyclones. Wet or dry ESPs could be used depending upon the
particulate loading of the gas stream.
References For Section 9.8.3
1. 1987 Census of Manufacturers, MC87-1-20-C, Industries Series, Preserved Fruits And
Vegetables.
2. G. Fuller and G. G. Dull, "Processing Of Horticultural Crops In The United States", in
Handbook Of Processing And Utilization In Agriculture, CRC Press, Inc., Boca Raton, FL,
1983.
3. N.W. Desrosier, Elements Of Food Technology, AVI Publishing Company, Westport, CT,
1977.
4. H. J. Rafson, Odor Emission Control For The Food Industry, Food Technology, June 1977.
9.8.3-4 EMISSION FACTORS 8/95
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9.9 Grain Processing
9.9.1 Grain Elevators And Processes
9.9.2 Cereal Breakfast Food
9.9.3 Pet Food
9.9.4 Alfalfa Dehydration
9.9.5 Pasta Manufacturing
9.9.6 Bread Baking
9.9.7 Corn Wet Milling
1/95 Food And Agricultural Industries 9.9-1
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9.9.1 Grain Elevators And Processes
[Work In Progress]
The recommended interim AP-42 Section on Grain Elevators And Processes is available either
through the Technology Transfer Network Bulletin Board System (TTN BBS) of EPA's Office Of Air
Quality Planning And Standards or from the Emission Factor And Inventory Group's Fax CHIEF
service.
The BBS can be accessed with a computer and modem at (919) 541-5407. The interim
Section is found on the BBS in the "Q&A's/Policies/Recommendations" area under the "AP-42/EF
Guidance" area of the "Clearinghouse For Emission Inventories And Factors" technical area.
The interim Section can be obtained also from the Fax CHIEF service by calling (919)
541-0548 or -5626 from the telephone handset of a facsimile machine and following the directions
provided to request a document.
For assistance with either of these procedures, call the Info CHIEF help desk, (919)
541-5285, between 9:00 am and 4:00 pm Eastern time, Tuesday through Friday.
The interim emission factors for Grain Elevators And Processes are subject to change pending
completion of emission source testing being conducted in early 1996.
1/95 Food And Agricultural Industries 9.9.1-1
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9.9.2 Cereal Breakfast Food
9.9.2,1 General1
Breakfast cereal products were originally sold as milled grains of wheat and oats that required
further cooking in the home prior to consumption. In this century, due to efforts to reduce the amount
of in-home preparation time, breakfast cereal technology has evolved from the simple procedure of
milling grains for cereal products that require cooking to the manufacturing of highly sophisticated
ready-to-eat products that are convenient and quickly prepared.
9.9.2.2 Process Description1"3
Breakfast cereals can be categorized into traditional (hot) cereals that require further cooking
or heating before consumption and ready-to-eat (cold) cereals that can be consumed from the box or
with the addition of milk. The process descriptions in this section were adapted primarily from
reference 3 and represent generic processing steps. Actual processes may vary considerably between
plants, even those manufacturing the same type of cereal.
Traditional Cereals -
Traditional cereals are those requiring cooking or heating prior to consumption and are made
from oats, farina (wheat), rice, and corn. Almost all (99 percent) of the traditional cereal market are
products produced from oats (over 81 percent) and farina (approximately 18 percent). Cereals made
from rice, corn (excluding corn grits), and wheat (other than farina) make up less than 1 percent of
traditional cereals.
Oat cereals. The three types of oat cereals are old-fashioned oatmeal, quick oatmeal, and
instant oatmeal. Old-fashioned oatmeal is made of rolled oat groats (dehulled oat kernels) and is
prepared by adding water and boiling for up to 30 minutes. Quick oat cereal consists of thinner flakes
made by rolling cut groats and is prepared by cooking for 1 to 15 minutes. Instant oatmeal is similar
to quick oats but with additional treatments, such as the incorporation of gum to improve hydration;
hot water is added but no other cooking is required. The major steps in the production of traditional
oat cereal include grain receiving, cleaning, drying, hulling, groat processing, steaming, and flaking.
Figure 9.9.2-1 is a generic process flow diagram for traditional oat cereal production.
Oats arrive at the mill via bulk railcar or truck and are sampled to ensure suitable quality for
milling. Once the grain is deemed acceptable, it is passed over a receiving separator to remove coarse
and fine material and binned according to milling criteria. Raw grain handling and processing is
discussed in AP-42 Section 9.9.1, Grain Elevators and Processes.
Cleaning removes foreign material, such as dust, stems, and weed seeds, and oats that are
unsuitable for milling. The cleaning process utilizes several devices to take advantage of particular
physical properties of the grain. For example, screens utilize the overall size of the grain, aspirators
and gravity tables utilize grain density, and discs with indent pockets and/or indent cylinders utilize the
grain length or shape. After completing the cleaning process, the grain is called clean milling oats or
green oats.
In the hulling process, most facilities use the impact huller, which separates the hull from the
groat by impact, rather than traditional stone hulling. The groat is the portion of the oat that remains
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GRAIN RECEIVING
PM
CLEANING
PM
HULLING
PM
GROAT
PROCESSING
STEAMING
VOC
FLAKING
PM
PACKAGING
9.9.2-2
Figure 9.9.2-1. Traditional oat cereal production.
EMISSION FACTORS
8/95
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after the hull has been removed and is the part processed for human consumption. In impact hulling,
the oats are fed through a rotating disc and flung out to strike the wall of the cylindrical housing
tangentially, which separates the hull from the groat. The mixed material then falls to the bottom of
the huller and is subjected to aspiration to separate the hulls from the groats. Impact hulling does not
require predrying of the oats, although some facilities still use the traditional dry-pan process to
impart a more nutty and less raw or green flavor to the final product. In the traditional dry-pan
process, the green oats are dried in a stack of circular pans heated indirectly by steam to a surface
temperature of 93° to 100°C (200° to 212°F). However, most facilities utilize enclosed vertical or
horizontal grain conditioners or kilns to dry the groat after it has been separated from the hull because
of the inefficiency of drying hulls. The grain conditioners have both direct (sparging) steam and
indirect steam to heat the oats and impart flavor to the groats comparable to that resulting from the
pan drying process.
After the groats are hulled, they are sized to separate the largest groats from the average-sized
groats. The large groats are used to make the so-called old-fashioned oats and the other groats are
cut using steel cutters to make quick oats. After groat processing, the groats (either whole or cut
pieces, depending on the end product) typically pass through an atmospheric steamer located above
the rollers. The groats must remain in contact with the live steam long enough to achieve a moisture
content increase from 8 to 10 percent up to 10 to 12 percent, which is sufficient to provide
satisfactory flakes when the whole or steel-cut groats are rolled.
The production of old-fashioned oat and quick oat flakes is the same, except for the starting
material (old-fashioned oats start with whole groats and quick oats start with steel-cut groats). Both
products are rolled between two cast iron equal-speed rolls in rigid end frames. Quick-oat products
are rolled thinner than old-fashioned oats. Following rolling, the flakes are typically cooled and
directed to packaging bins for holding.
Instant oatmeal is processed similarly to quick oatmeal through the steaming stage. After the
groats are steamed, they are rolled thinner than those of quick oatmeal. The final product, along with
specific amounts of hydrocolloid gum, salt, and other additives, is packaged into premeasured
individual servings. The most important difference between instant oatmeal and other oatmeal
products is the addition of hydrocolloid gum, which replaces the natural oat gums that would be
leached from the flakes during traditional cooking, thus accelerating hydration of the flakes.
The standard package for old-fashioned and quick oatmeal is the spirally wound two-ply fiber
tube with a paper label. Folded cartons are also used to package old-fashioned and quick oatmeal.
Most of the instant hot cereals are packed in individual, single-serving pouches.
Farina cereals. Cereals made from farina are the second largest segment of the traditional hot
cereal market, making up 18 percent. Farina is essentially wheat endosperm in granular form that is
free from bran and germ. The preferred wheat for producing farina is hard red or winter wheat
because the granules of endosperm for these types of wheat stay intact when hot cereals are prepared
at home. As shown in Figure 9.9.2-2, farina cereal production begins with the receiving and milling
of wheat. Information on wheat receiving, handling, and milling can be found in AP-42
Section 9.9.1, Grain Elevators and Processes. After milling, traditional farina cereals are packaged.
Quick cook farina cereals are prepared primarily by the addition of disodium phosphate, with or
without the further addition of a protcolytic enzyme. An instant (cook-in-the-bowl) product may be
made by wetting and pressure-cooking the farina, then flaking and redrying prior to portion
packaging.
Wheat, rice, and corn cereals. Other traditional cereals include whole wheat cereals, rice
products, and corn products. These cereals make up less than 1 percent of the traditional cereal
8/95 Food And Agricultural Industry 9.9.2-3
-------
GRAIN RECEIVING f ^ PM
MILLING ^- PM
T:
STEAMING8 I- ^~ VOC
FLAKING*
m
HEAT TREATMENT j- ^~ VOC
PACKAGING [ -^- PM
aNot required for traditional or quick-cooking farina cereals.
9.9.2-4
Figure 9.9.2-2. Typical instant cook farina cereal production.
EMISSION FACTORS
8/95
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market. Whole wheat traditional cereals include milled, rolled, and cracked wheat products. Milled
cereals are made in a hard wheat flour mill by drawing off medium-grind milled streams. Rice
products have yet to find acceptance as a hot cereal, although rice can be ground into particles about
the size of farina and cooked into a hot cereal resembling farina. Corn products include corn grits,
cornmeal, corn flour, and corn bran. Corn grits are served primarily as a vegetable accompaniment
to the main breakfast item and are not usually classified as a breakfast cereal although they can be
consumed as such. Cornmeal, corn flour, and corn bran are used primarily as ingredients in the
preparation of other foods and are not classified as breakfast cereals.
Ready-To-Eat Cereals -
In the United States, the word "cereal" is typically synonymous with a processed product that
is suitable for human consumption with or without further cooking at home and is usually eaten at
breakfast. Ready-to-eat cereals are typically grouped by cereal form rather than the type of grain
used. These groups are flaked cereals, extruded flaked cereals, gun-puffed whole grains, extruded
gun-puffed cereals, oven-puffed cereals, shredded whole grains, extruded shredded cereals, and
granola cereals.
Flaked cereals. Flaked cereals are made directly from whole grain kernels or parts of kernels
of corn, wheat, or rice and are processed in such a way as to obtain particles, called flaking grits,
that form one flake each. The production of flaked cereals involves preprocessing, mixing, cooking,
delumping, drying, cooling and tempering, flaking, toasting, and packaging. A general process flow
diagram for cereal flake production is presented in Figure 9.9.2-3. Grain preparation, including
receiving, handling, cleaning, and hulling, for flaked cereal production is similar to that discussed
under traditional cereal production and in AP-42 Section 9.9.1, Grain Elevators and Processes.
Before the grains can be cooked and made into flakes, they must undergo certain preprocessing steps.
For corn, this entails dry milling regular field corn to remove the germ and the bran from the kernel,
leaving chunks of endosperm. Wheat is preprocessed by steaming the kernels lightly and running
them through a pair of rolls to break open the kernels. Care is taken not to produce flour or fine
material. Rice does not require any special preprocessing steps for the production of rice flakes other
than those steps involved in milling rough rice to form the polished head rice that is the normal
starting material.
The corn, wheat, or rice grits are mixed with a flavor solution that includes sugar, malt, salt,
and water. Weighed amounts of raw grits and flavor solution are then charged into rotating batch
cookers. After the grits are evenly coated with the flavor syrup, steam is released into the rotating
cooker to begin the cooking process. The cooking is complete when each kernel or kernel part has
been changed from a hard, chalky white to a soft, translucent, golden brown. When the cooking is
complete, rotation stops, the steam is turned off, and vents located on the cooker are opened to
reduce the pressure inside the cooker to ambient conditions and to cool its contents. The exhaust
from these vents may be connected to a vacuum system for more rapid cooling. After pressure is
relieved, the cooker is uncapped and the rotation restarted. The cooked grits are then dumped onto
moving conveyor belts located under the cooker discharge. The conveyors then pass through
delumping equipment to break and size the loosely held-together grits into mostly single grit particles.
Large volumes of air are typically drawn through the delumping equipment to help cool the product.
It may be necessary to perform delumping and cooling in different steps to get proper separation of
the grits so that they are the optimum size for drying; in this case, cooling is typically performed first
to stop the cooking action and to eliminate stickiness from the grit surface. After cooking and
delumping, the grits are metered in a uniform flow to the dryer. Drying is typically performed at
temperatures below 121 °C (250°F) and under controlled humidity, which prevents case hardening of
the grit and greatly decreases the time needed for drying to the desired moisture level. After drying,
the grits are cooled to ambient temperature, usually in an unheated section of the dryer. After they
are cooled, the grits are tempered by holding them in large accumulating bins to allow the moisture
8/95 Food And Agricultural Industry 9.9.2-5
-------
PREPROCESSING
PM
ADDITIVES-
MIXER
BLENDED GRITS
COOKER
VOC
COOKED LUMPS
OF GRITS
DELUMPER
INDIVIDUAL COOKED
GRIT PIECES
DRYER
DRY GRIT
PIECES
COOLING AND
TEMPERING
COOL/DRY
GRIT PROCESS
FLAKER
FLAKED PIECES
DRYER/
TOASTER
PACKAGING
VOC
VOC
VOC
PM
VOC
PM
VOC
9.9.2-6
Figure 9.9.2-3. Process diagram for cereal flake production.1
EMISSION FACTORS
8/95
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content to equilibrate between the grit particles as well as from the center of the individual particles to
the surface. After tempering, the grits pass between pairs of very large metal rolls that press them
into very thin flakes. Flakes are toasted by suspending them in a hot air stream, rather than by laying
them onto a flat baking surface. The ovens, sloped from feed end to discharge end, are perforated on
the inside to allow air flow. These perforations are as large as possible for good air flow but small
enough so that flakes cannot catch in them. The toasted flakes are then cooled and sent to packaging.
Extruded flake cereals. Extruded flakes differ from traditional flakes in that the grit for
flaking is formed by extruding mixed ingredients through a die and cutting pellets of the dough into
the desired size. The steps in extruded flake production are preprocessing, mixing, extruding, drying,
cooling and tempering, flaking, toasting, and packaging. Figure 9.9.2-4 presents a generic process
flow diagram for the production of extruded flake cereals. The primary difference between extruded
flake production and traditional flake production is that extruded flakes replace the cooking and
delumping steps used in traditional flake production with an extruding step. The extruder is a long,
barrel-like apparatus that performs several operations along its length. The first part of the barrel
kneads or crushes the grain and mixes the ingredients together. The flavor solution may be added
directly to the barrel of the extruder by means of a metering pump. Heat input to the barrel of the
extruder near the feed point is kept low to allow the ingredients to mix properly before any cooking
or gelatinization starts. Heat is applied to the center section of the extruder barrel to cook the
ingredients. The die is located at the end of the last section, which is generally cooler than the rest of
the barrel. The dough remains in a compact form as it extrudes through the die and a rotating knife
slices it into properly-sized pellets. The remaining steps for extruded flakes (drying, cooling, flaking,
toasting, and packaging) are the same as for traditional flake production.
Gun-puffed whole grain cereals. Gun-puffed whole grains are formed by cooking the grains
and then subjecting them to a sudden large pressure drop. As steam under pressure in the interior of
the grain seeks to equilibrate with the surrounding lower-pressure atmosphere, it forces the grains to
expand quickly or "puff." Rice and wheat are the only types of grain used in gun-puffed whole grain
production, which involves pretreatment, puffing, screening, drying, and cooling. A general process
flow diagram is shown in Figure 9.9.2-5. Wheat requires pretreating to prevent the bran from
loosening from the grain in a ragged, haphazard manner, in which some of the bran adheres to the
kernels and other parts to be blown partially off the kernels. One form of pretreatment is to add
4 percent, by weight, of a saturated brine solution (26 percent salt) to the wheat. Another form of
pretreatment, called pearling, removes part of the bran altogether before puffing. The only
pretreatment required for rice is normal milling to produce head rice. Puffing can be performed with
manual single-shot guns, automatic single-shot, automatic multiple-shot guns, or continuous guns. In
manual single-shot guns, grain is loaded into the opening of the gun and the lid is closed and sealed.
As the gun begins to rotate, gas burners heat the sides of the gun body causing the moisture in the
grain to convert to steam. When the lid is opened, the sudden change in pressure causes the grain to
puff. Automatic single-shot guns operate on the same principle, except that steam is injected directly
into the gun body. Multiple-shot guns have several barrels mounted on a slowly rotating wheel so
that each barrel passes the load and fire positions at the correct time. The load, steam, and fire
process for any one barrel is identical to that of the single-shot gun. After the grain is puffed, it is
screened and dried before it is packaged. The final product is very porous and absorbs moisture
rapidly and easily so it must be packaged in materials that possess good moisture barrier qualities.
Extruded gun-puffed cereals. Extruded gun-puffed cereals use a meal or flour as the starting
ingredient instead of whole grains. The dough cooks in the extruders and is then formed into the
desired shape when extruded through a die. The extrusion process for gun-puffed cereals is similar to
that for extruded flake production. After the dough is extruded, it is dried and tempered. It then
undergoes the same puffing and final processing steps as described for whole grain gun-puffed
cereals.
8/95 Food And Agricultural Industry 9.9.2-7
-------
ADDITIVES
9.9.2-8
Figure 9.9.2-4. Process diagram for extruded flake production.1
EMISSION FACTORS
8/95
-------
PRETREATMENT
8/95
Figure 9.9.2-5. Gun-puffed whole grain production.1
Food And Agricultural Industry
9.9.2-9
-------
Oven-puffed cereals. Oven-puffed cereals are made almost exclusively using whole-grain rice
or corn, or mixtures of these two grains, because rice and corn inherently puff in the presence of high
heat and the proper moisture content. The grains are mixed with sugar, salt, water, and malt and
then pressure-cooked. After cooking, the grain is conveyed through a cooling and sizing operation.
After cooling and sizing, the kernels are dried and tempered. The kernels are then passed through
flaking rolls to flatten them slightly. The kernels are dried again and then oven-puffed, which
requires a proper balance between kernel moisture content and oven temperature. After puffing, the
cereal is cooled, fortified with vitamins (if necessary), and frequently treated with antioxidants to
preserve freshness. The final product is then packaged.
Whole-grain shredded cereals. Wheat (white wheat) is primarily used to produce shredded
whole grains. The steps involved in producing whole-grain shredded cereal are grain cleaning,
cooking, cooling and tempering, shredding, biscuit formation, biscuit baking, and packaging. A
generic process flow diagram for shredded cereal production is presented in Figure 9.9.2-6. Cooking
is typically performed in batches with excess water at temperatures slightly below the boiling point at
atmospheric pressure. Cooking vessels usually have horizontal baskets big enough to hold 50 bushels
of raw wheat. Steam is injected directly into the water to heat the grain. After the cooking cycle is
completed, the water is drained from the vessel and the cooked wheat is dumped and conveyed to
cooling units, which surface-dry the wheat and reduce the temperature to ambient levels, thus
stopping the cooking process. After the grain is cooled, it is placed in large holding bins and allowed
to temper. The shredding process squeezes the wheat kernels between one roll with a smooth surface
and another roll with a grooved surface. A comb is positioned against the grooved roll and the comb
teeth pick the wheat shred from the groove. There are many variations in the grooved roll. After the
shreds are produced, they fall in layers onto a conveyer moving under the rolls. After the web of
many layers of shreds reaches the end of the shredder, it is fed through a cutting device to form the
individual biscuits. The edges of the cutting device are dull, rather than sharp, so that the cutting
action compresses the edges of the biscuit together to form a crimped joint, which holds the shreds
together in biscuit form. After the individual biscuits are formed, they are baked in a band or
continuous conveyor-belt oven. After the biscuits are baked and dried, they are ready for packaging.
Extruded shredded cereals. Extruded shredded cereals are made in much the same way as
whole-grain shredded cereals except that extruded shredded cereals use a meal or flour as a raw
material instead of whole grains. Raw grains include wheat, corn, rice, and oats, and, because the
grains are used in flour form, they can be used alone or in mixtures. The steps involved in extruded
shredded cereal production are grain preprocessing (including grain receiving, handling, and milling),
mixing, extruding, cooling and tempering, shredding, biscuit formation, baking, drying, and
packaging. The preprocessing, mixing, extruding, and cooling and tempering steps are the same as
those discussed for other types of cereal. Shredding, biscuit formation, baking, drying, and
packaging are the same as for whole-grain shredded cereal. Extruded shredded cereals are typically
made into small, bite-size biscuits, instead of the larger biscuits of whole-grain shredded wheat.
Granola cereals. Granola cereals are ready-to-eat cereals that are prepared by taking regular,
old-fashioned whole-rolled oats or quick-cooking oats and mixing them with other ingredients, such as
nut pieces, coconut, brown sugar, honey, malt extract, dried milk, dried fruits, water, cinnamon,
nutmeg, and vegetable oil. This mixture is then spread in a uniform layer onto the band of a
continuous dryer or oven. The toasted layer is then broken into chunks.
Packaging -
The package materials for ready-to-eat breakfast cereals include printed paperboard cartons,
protective liners, and the necessary adhesives. The cartons are printed and produced by carton
suppliers and are delivered, unfolded and stacked on pallets, to the breakfast cereal manufacturers.
9.9.2-10 EMISSION FACTORS 8/95
-------
GRAIN
CLEANING
PM
COOKING
T
COOKING AND
TEMPERING
i
voc
VOC
PM
( V ) SHREDDING-
VOC
»
BISCUIT
FORMATION
BAKING
VOC
DRYING
VOC
PACKAGING
VOC
8/95
Figure 9.9.2-6. Whole grain shredded cereal production.
Food And Agricultural Industry
9.9.2-11
-------
The liners, also supplied by outside sources, must be durable and impermeable to moisture or
moisture vapor. However, cereals that are not hygroscopic and/or retain satisfactory texture in
moisture equilibrium with ambient atmosphere do not require moisture-proof liners. The most
common type of liners used today are made of high-density polyethylene (HDPE) film. The
adhesives used in cereal packaging are water-based emulsions and hot melts. The cereal industry is
the second largest user of adhesives for consumer products. Several variations of packaging lines
may be used in the ready-to-eat breakfast cereal industry, including lines that fill the liners either
before or after they have been inserted into the carton and lines that utilize more manual labor and
less automated equipment.
9.9.2.3 Emissions And Controls
Air emissions may arise from a variety of sources in breakfast cereal manufacturing.
Paniculate matter (PM) emissions result mainly from solids handling and mixing. For breakfast
cereal manufacturing, PM emissions occur during the milling and processing of grain, as the raw
ingredients are dumped, weighed, and mixed, as the grains are hulled, and possibly during screening,
drying, and packaging. Emission sources associated with grain milling and processing include grain
receiving, precleaning and handling, cleaning house separators, milling, and bulk loading. Applicable
emission factors for these processes are presented in AP-42 Section 9.9.1, Grain Elevators and
Processes. There are no data on PM emissions from mixing of ingredients or packaging for breakfast
cereal production.
Volatile organic compound (VOC) emissions may potentially occur at almost any stage in the
production of breakfast cereal, but most usually are associated with thermal processing steps, such as
drying, steaming, heat treatment, cooking, toasting, extruding, and puffing. Adhesives used during
packaging of the final product may also be a source of VOC emissions. No information is available,
however, on any VOC emissions resulting from these processes of breakfast cereal manufacturing.
Control technology to control PM emissions from breakfast cereal manufacturing is similar to
that discussed in AP-42 Section 9.9.1, Grain Elevators and Processes. Because of the operational
similarities, emission control methods are similar in most grain milling and processing plants.
Cyclones or fabric filters are often used to control emissions from grain handling operations
(e. g., unloading, legs, cleaners, etc.) and also from other processing operations. Fabric filters are
used extensively in flour mills. However, certain operations within milling operations are not
amenable to the use of these devices and alternatives are needed. Wet scrubbers, for example, are
applied where the effluent gas stream has a high moisture content. No information exists for VOC
emission control technology for breakfast cereal manufacturing.
References For Section 9.9.2
1. R. E. Tribelhorn, "Breakfast Cereals", Handbook Of Cereal Science And Technology,
K. J. Lorenz and K. Kulp, Editors. Marcel Dekker, Inc., 1991.
2. 1987 Census Of Manufactures: Grain Mill Products, Industry Series. U. S.
Department of Commerce, Bureau of Census. Issued April 1990.
3. R. B. Fast, "Manufacturing Technology Of Ready-To-Eat Cereals", Breakfast Cereals
And How They Are Made, R. B. Fast and E. F. Caldwell, Editors. American
Association of Cereal Chemists, Inc., 1990.
4. D. L. Maxwell and J. L. Holohan, "Breakfast Cereals", Elements Of Food
Technology, N. W. Desrosier, Editor. AVI Publishing Company, Inc., 1977.
9.9.2-12 EMISSION FACTORS 8/95
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9.9.3 Pet Food
[Work In Progress]
1/95 Food And Agricultural Industries 993-1
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9.9.4 Alfalfa Dehydrating
9.9.4.1 General1"2
Dehydrated alfalfa is a meal product resulting from the rapid drying of alfalfa by artificial
means. Alfalfa meal is processed into pellets for use in chicken rations, cattle feed, hog rations, sheep
feed, turkey mash, and other formula feeds. It is important for its protein content, growth and
reproductive factors, pigmenting xanthophylls, and vitamin contributions.
9.9.4.2 Process Description1"5
A schematic of a generalized alfalfa dehydrator plant is given in Figure 9.9.4-1. Standing
alfalfa is windrowed in the field to allow wilting to reduce moisture to an acceptable level balancing
energy requirements, trucking requirements, and dehydrator capacity while maintaining the alfalfa
quality and leaf quantity. The windrowed alfalfa is then chopped and hauled to the dehydration plant.
The truck dumps the chopped alfalfa (wet chops) onto a self-feeder, which carries it into a direct-fired
rotary drum. Within the drum, the wet chops are dried from an initial moisture content of about 30 to
70 percent (by weight, wet basis) to about 6 to 12 percent. Typical combustion gas temperatures
within the gas-fired drum range from 154° to 816°C (300° to 1500°F) at the inlet to 60° to 95°C (140°
to 21()°F) at the outlet.
From the drying drum, the dry chops are pneumatically conveyed into a primary cyclone that
separates them from the high-moisture, high-temperature exhaust stream. From the primary cyclone,
the chops are fed into a hammermill, which grinds the dry chops into a meal. The meal is
pneumatically conveyed from the hammermill into a meal collector cyclone in which the meal is
separated from the airstream and discharged into a holding bin. The exhaust is recycled to a bag filter
(baghouse). The meal is then fed into a pellet mill where it is steam conditioned and extruded into
pellets.
From the pellet mill, the pellets are either pneumatically or mechanically conveyed to a cooler,
through which air is drawn to cool the pellets and, in some cases, remove fines. Fines are more
commonly removed using shaker screens located ahead of or following the cooler, with the fines being
conveyed back into the meal collector cyclone, meal bin, or pellet mill. Cyclone separators may be
employed to separate entrained fines in the cooler exhaust and to collect pellets when the pellets are
pneumatically conveyed from the pellet mill to the cooler.
Following cooling and screening, the pellets are transferred to bulk storage. Dehydrated alfalfa
is most often stored and shipped in pellet form, although the pellets may also be ground in a
hammermill and shipped in meal form. When the finished or ground pellets are pneumatically or
mechanically transferred to storage or loadout, additional cyclones may be used for product airstream
separation.
9.9.4.3 Emissions And Controls1"3'5"7
Particulate matter (PM) is the primary pollutant emitted from alfalfa dehydrating plants,
although some odors may arise from the organic volatiles driven off during drying and pellet
formation. The major source of PM emissions is the primary cyclone following the dryer drum.
9/96 Food And Agricultural Industry 9.9.4-1
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yOA3ANOO OIlWinBNd *>
9.9.4-2
EMISSION FACTORS
9/96
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Lesser emission sources include the downstream cyclone separators and the bagging and loading
operations.
Emission factors for various dryer types utilized in alfalfa dehydrating plants are given in
Table 9.9.4-1. Note that, although these sources are common to many plants, there will be
considerable variation from the generalized flow diagram in Figure 9.9.4-1 depending on the desired
nature of the product, the physical layout of the plant, and the modifications made for air pollution
control.
Table 9.9.4-1. EMISSION FACTORS FOR ALFALFA DEHYDRATION3
EMISSION FACTOR RATING: D
Source
Triple-pass dryer cyclone
- Gas-fired
(SCC 3-02-001-11)
- Coal-firedb
(SCC 3-02-001-12)
Single-pass dryer cyclone
- Gas-fired
(SCC 3-02-001-15)
- Wood-fired
(SCC 3-02-001 -17)
Meal collector cyclone
(SCC 3-02-001-03)
- Bag filter
Pellet collector cyclone
(SCC 3-02-001-07)
Pellet cooler cyclone
(SCC 3-02-001-04)
Storage bin cyclone
(SCC 3-02-001-20)
Paniculate (PM)
Filterable
4.8
7.5
4.1
3.1
ND
ND
ND
ND
Condensible
1.0
ND
0.65
1.3
ND
ND
ND
ND
VOC
ND
ND
ND
ND
NA
ND
NA
NA
Ref.
8-9
13
10-11
12,14
a Emission factor units are Ib/ton of finished pellet produced, unless noted. To convert from
Ib/ton to kg/Mg, multiply by 0.5. SCC = Source Classification Code. ND = No data.
NA = Not applicable.
Emission factor based on quantity of dried alfalfa to hammermill.
Air pollution control (and product recovery) is accomplished in alfalfa dehydrating plants in a
variety of ways. A simple, yet effective technique is the proper maintenance and operation of the
alfalfa dehydrating equipment. Paniculate emissions can be reduced significantly if the feeder
discharge rates are uniform, if the dryer furnace is operated properly, if proper airflows are employed
in the cyclone collectors, and if the hammermill is well maintained and not overloaded. It is
especially important in this regard not to overdry and possibly burn the chops as this results in the
generation of smoke and increased fines in the grinding and pelletizing operations.
Equipment modification provides another means of paniculate control. Existing cyclones can
be replaced with more efficient cyclones and concomitant air flow systems. In addition, the furnace
and burners can be modified or replaced to minimize flame impingement on the incoming green chops.
9/96
Food And Agricultural Industry
9.9.4-3
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In plants where the hammermill is a production bottleneck, a tendency exists to overdry the chops to
increase throughput, which results in increased emissions. Adequate hammermill capacity can reduce
this practice. Recent improvements in process technique and emission control technology have
reduced paniculate emissions from dehydration facilities. Future technology should contribute to
further reductions in paniculate emissions.
Secondary control devices can be employed on the cyclone collector exhaust streams.
Generally, this practice has been limited to the installation of secondary cyclones or fabric filters on
the meal collector, pellet collector or pellet cooler cyclones. Primary cyclones are not controlled by
fabric filters because of the high moisture content in the resulting exhaust stream. Medium energy wet
scrubbers are effective in reducing paniculate emissions from the primary cyclones, but have only
been installed at a few plants.
Some plants employ cyclone effluent recycle systems for paniculate control. One system
skims off the particulate-laden portion of the primary cyclone exhaust and returns it to the alfalfa
dryer. Another system recycles a large portion of the meal collector cyclone exhaust back to the
hammermill. Both systems can be effective in controlling particulates but may result in operating
problems, such as condensation in the recycle lines and plugging or overheating of the hammermill.
References For Section 9.9.4
1. Air Pollution From Alfalfa Dehydrating Mills, Technical Report A 60-4, Robert A. Taft
Sanitary Engineering Center, U.S.P.H.S., Department Of Health, Education, And Welfare,
Cincinnati, OH.
2. Schafer, R.D., "How Ohio Is Solving The Alfalfa Dust Problem", A.M.A. Archives Of
Industrial Health, 17:61-69, January 1958.
3. Source information supplied by Ken Smith of the American Dehydrators Association, Mission,
KS, December 1975.
4. Written correspondence from W. Cobb, American Alfalfa Processors Association, to
T. Campbell, Midwest Research Institute, Updated alfalfa dehydration process diagram,
May 18, 1995.
5. Telephone conversation with D. Burkholder, Shofstall Alfalfa, and T. Lapp and T. Campbell,
Midwest Research Institute, Clarification of alfalfa dehydration process, June 13, 1995.
6. Emission Factor Development For The Feed And Grain Industry, EPA-450/3-75-054, U. S.
Environmental Protection Agency, Research Triangle Park, NC, October 1974.
7. Paniculate Emissions From Alfalfa Dehydrating Plants - Control Costs And Effectiveness,
EPA 650/2-74-007, U. S. Environmental Protection Agency, Research Triangle Park, NC,
January 1974.
8. Source Emissions Report For Gothenburg Feed Products Co., Gothenburg, NE, AirSource
Technologies, Lenexa, KS, October 8, 1993.
9. Source Emissions Report For Shofstall Alfalfa, Alfalfa Dehydrating Facility, Odessa, NE,
AirSource Technologies, Lenexa, KS, October 15, 1993.
9.9.4-4 EMISSION FACTORS 9/96
-------
10. Source Emissions Report For Morrison & Quirk, Inc., Alfalfa Dehydrating Facility, Lyons, NE,
AirSource Technologies, Lenexa, KS, October 15, 1993.
11. Source Emissions Report For Lexington Alfalfa Dehydrators, Inc., Alfalfa Dehydrating
Facility, Dan, NE, AirSource Technologies, Lenexa, KS, October 15, 1993.
12. Stack Paniculate Samples Collected At Verhoff Alfalfa, Hoytville, OH, Affiliated
Environmental Services, Inc., Sandusky, OH, September 25, 1992.
13. Emission Test Report For Toledo Alfalfa, Oregon, OH, Owens-Illinois Analytical Services,
Toledo, OH, June 4, 1987.
14. Stack Paniculate Samples Collected At Verhoff Alfalfa, Ottawa, OH, Affiliated Environmental
Services, Inc., Sandusky, OH, June 28, 1995.
9/96 Food And Agricultural Industry 9.9.4-5
-------
9.9.5 Pasta Manufacturing
9.9.5.1 General1-2
Although pasta products were first introduced in Italy in the 13th century, efficient
manufacturing equipment and high-quality ingredients have been available only since the 20th century.
Prior to the industrial revolution, most pasta products were made by hand in small shops. Today,
most pasta is manufactured by continuous, high capacity extruders, which operate on the auger
extrusion principle in which kneading and extrusion are performed in a single operation. The
manufacture of pasta includes dry macaroni, noodle, and spaghetti production.
9.9.5.2 Process Description1'2
Pasta products are produced by mixing milled wheat, water, eggs (for egg noodles or egg
spaghetti), and sometimes optional ingredients. These ingredients are typically added to a continuous,
high capacity auger extruder, which can be equipped with a variety of dies that determine the shape
of the pasta. The pasta is then dried and packaged for market.
Raw Materials —
Pasta products contain milled wheat, water, and occasionally eggs and/or optional ingredients.
Pasta manufacturers typically use milled durum wheat (semolina, durum granulars, and durum flour)
in pasta production, although farina and flour from common wheat are occasionally used. Most pasta
manufacturers prefer semolina, which consists of fine particles of uniform size and produces the
highest quality pasta product. The water used in pasta production should be pure, free from off-
flavors, and suitable for drinking. Also, since pasta is produced below pasteurization temperatures,
water should be used of low bacterial count. Eggs (fresh eggs, frozen eggs, dry eggs, egg yolks, or
dried egg solids) are added to pasta to make egg noodles or egg spaghetti and to improve the
nutritional quality and richness of the pasta. Small amounts of optional ingredients, such as salt,
celery, garlic, and bay leafs, may also be added to pasta to enhance flavor. Disodium phosphate may
be used to shorten cooking time. Other ingredients, such as gum gluten, glyceryl monostearate, and
egg whites, may also be added. All optional ingredients must be clearly labeled on the package.
Wheat Milling —
Durum wheat is milled into semolina, durum granular, or durum flour using roll mills.
Semolina milling is unique in that the objective is to prepare granular middlings with a minimum of
flour production. Grain milling is discussed in AP-42 Section 9.9,1, Grain Elevators and Processes.
After the wheat is milled, it is mixed with water, eggs,, and any other optional ingredients.
Mixing —
In the mixing operation, water is added to the milled wheat in a mixing trough to produce
dough with a moisture content of approximately 31 percent. Eggs and any optional ingredients may
also be added. Most modern pasta presses are equipped with a vacuum chamber to remove air
bubbles from the pasta before extruding. If the air is not removed prior to extruding, small bubbles
8/95 Food And Agricultural Industry 9.9.5-1
-------
will form in the pasta which diminish the mechanical strength and give the finished product a white,
chalky appearance.
Extruding —
After the dough is mixed, it is transferred to the extruder. The extrusion auger not only
forces the dough through the die, but it also kneads the dough into a homogeneous mass, controls the
rate of production, and influences the overall quality of the finished product. Although construction
and dimension of extrusion augers vary by equipment manufacturers, most modern presses have
sharp-edged augers that have a uniform pitch over their entire length. The auger fits into a grooved
extrusion barrel, which helps the dough move forward and reduces friction between the auger and the
inside of the barrel. Extrusion barrels are equipped with a water cooling jacket to dissipate the heat
generated during the extrusion process. The cooling jacket also helps to maintain a constant extrusion
temperature, which should be approximately 51 °C (124°F). If the dough is too hot (above 74°C
[165°F]), the pasta will be damaged.
Uniform flow rate of the dough through the extruder is also important. Variances in the flow
rate of the dough through the die cause the pasta to be extruded at different rates. Products of
nonuniform size must be discarded or reprocessed, which adds to the unit cost of the product. The
inside surface of the die also influences the product appearance. Until recently, most dies were made
of bronze, which was relatively soft and required repair or periodic replacement. Recently, dies have
been improved by fitting the extruding surface of the die with Teflon® inserts to extend the life of the
dies and improve the quality of the pasta.
Drying —
Drying is the most difficult and critical step to control in the pasta production process. The
objective of drying is to lower the moisture content of the pasta from approximately 31 percent to 12
to 13 percent so that the finished product will be hard, retain its shape, and store without spoiling.
Most pasta drying operations use a preliminary drier immediately after extrusion to prevent the pasta
from sticking together. Predrying hardens the outside surface of the pasta while keeping the inside
soft and plastic. A final drier is then used to remove most of the moisture from the product.
Drying temperature and relative humidity increments are important factors in drying. Since
the outside surface of the pasta dries more rapidly than the inside, moisture gradients develop across
the surface to the interior of the pasta. If dried too quickly, the pasta will crack, giving the product a
poor appearance and very low mechanical strength. Cracking can occur during the drying process or
as long as several weeks after the product has left the drier. If the pasta is dried too slowly, it tends
to spoil or become moldy during the drying process. Therefore, it is essential that the drying cycle
be tailored to meet the requirements of each type of product. If the drying cycle has been successful,
the pasta will be firm but also flexible enough so that it can bend to a considerable degree before
breaking.
Packaging —
Packaging keeps the product free from contamination, protects the pasta from damage during
shipment and storage, and displays the product favorably. The principal packaging material for
noodles is the cellophane bag, which provides moisture-proof protection for the product and is used
easily on automatic packaging machines, but is difficult to stack on grocery shelves. Many
manufacturers utilize boxes instead of bags to package pasta because boxes are easy to stack, provide
good protection for fragile pasta products, and offer the opportunity to print advertising that is easier
to read than on bags.
9.9.5-2 EMISSION FACTORS 8/95
-------
9.9.5.3 Emissions and Controls
Air emissions may arise from a variety of sources in pasta manufacturing. Particulate
matter (PM) emissions result mainly from solids handling and mixing. For pasta manufacturing, PM
emissions occur during the wheat milling process, as the raw ingredients are mixed, and possibly
during packaging. Emission sources associated with wheat milling include grain receiving,
precleaning/handling, cleaning house, milling, and bulk loading. Applicable emission factors for
these processes are presented in AP-42 Section 9.9.1, Grain Elevators and Processes. There are no
data for PM emissions from mixing of ingredients or packaging for pasta production.
Volatile organic compound (VOC) emissions may potentially occur at almost any stage in the
production of pasta, but most usually are associated with thermal processing steps, such as pasta
extruding or drying. No information is available on any VOC emissions due to the heat generated
during pasta extrusion or drying.
Control of PM emissions from pasta manufacturing is similar to that discussed in AP-42
Section 9.9.1, Grain Elevators and Processes. Because of the operational similarities, emission
control methods used in grain milling and processing plants are similar to those in grain elevators.
Cyclones or fabric filters are often used to control emissions from the grain handling operations
(e. g., unloading, legs, cleaners, etc.) and also from other processing operations. Fabric filters are
used extensively in flour mills. However, certain operations within milling operations are not
amenable to the use of these devices and alternatives are needed. Wet scrubbers, for example, may
be applied where the effluent gas stream has a high moisture content.
References for Section 9.9.5
1. D. E. Walsh and K. A. Gilles, "Pasta Technology", Elements Of Food Technology,
N. W. Desrosier, Editor, AVI Publishing Company, Inc., 1977.
2. 1992 Census Of Manufactures: Miscellaneous Food And Kindred Products,
Preliminary Report Industry Series, U. S. Department of Commerce, Bureau of
Census, Issued August 1994.
8/95 Food And Agricultural Industry 9.9.5-3
-------
9.9.6 Bread Baking
[Work In Progress]
1/95 Food And Agricultural Industries 9.9.6-1
-------
9.9.6 Bread Baking
USEPA Recommendation for Estimating VOC Emissions from Bread Bakeries
The Emissions Inventory Branch recommends the equation given in "Alternative Control
Technology Document for Bakery Oven Emissions" (EPA 453/R-92-017, December 1992) for
estimating VOC emissions from yeast-raised bread baking point sources. The
equation is:
VOC E.F. = 0.95Yi+0.195ti-0.51S-0.86ts+1.90
where
VOC E.F. = pounds VOC per ton of baked bread
Yi = initial baker's percent of yeast
ti = total yeast action time in hours
S = final (spike) baker's percent of yeast
ts = spiking time in hours
This equation will be incorporated into a future revision of AP-42 section 9.9.6. Full details on
the derivation and use of the equation are contained in the ACT document cited above. Copies of
the ACT document are available - as supplies permit - from the Library Services Office (MD-35), U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina 27711. It is also
available for $27.00 (stock number PB93-157618) from the National Technical Information Service,
5285 Port Royal Road, Springfield, Virginia 22161, phone (800) 553-6847.
2/97 Food And Agricultural Industries 996-1
-------
9.9.7 Corn Wet Milling
9.9.7.1 General1
Establishments in corn wet milling are engaged primarily in producing starch, syrup, oil,
sugar, and byproducts such as gluten feed and meal, from wet milling of corn and sorghum. These
facilities may also produce starch from other vegetables and grains, such as potatoes and wheat. In
1994, 27 corn wet milling facilities were reported to be operating in the United States.
9.9.7.2 Process Description1"4
The corn wet milling industry has grown in its 150 years of existence into the most diversified
and integrated of the grain processing industries. The corn refining industry produces hundreds of
products and byproducts, such as high fructose com syrup (HFCS), corn syrup, starches, animal feed,
oil, and alcohol.
In the corn wet milling process, the corn kernel (see Figure 9.9.7-1) is separated into
3 principal parts: (1) the outer skin, called the bran or hull; (2) the germ, containing most of the oil;
and (3) the endosperm (gluten and starch). From an average bushel of corn weighing 25 kilograms
(kg) (56 pounds [lb]), approximately 14 kg (32 Ib) of starch is produced, about 6.6 kg (14.5 Ib) of
feed and feed products, about 0.9 kg (2 lb) of oil, and the remainder is water. The overall corn wet
milling process consists of numerous steps or stages, as shown schematically in Figure 9.9.7-2.
Shelled corn is delivered to the wet milling plant primarily by rail and truck and is unloaded
into a receiving pit. The corn is then elevated to temporary storage bins and scale hoppers for
weighing and sampling. The corn then passes through mechanical cleaners designed to remove
unwanted material, such as pieces of cobs, sticks, and husks, as well as meal and stones. The
cleaners agitate the kernels over a series of perforated metal sheets through which the smaller foreign
materials drop. A blast of air blows away chaff and dust, and electromagnets remove bits of metal.
Coming out of storage bins, the corn is given a second cleaning before going into "steep" tanks.
Steeping, the first step in the process, conditions the grain for subsequent milling and
recovery of corn constituents. Steeping softens the kernel for milling, helps break down the protein
holding the starch particles, and removes certain soluble constituents. Steeping takes place in a series
of tanks, usually referred to as steeps, which are operated in continuous-batch process. Steep tanks
may hold from 70.5 to 458 cubic meters (m3) (2,000 to 13,000 bushels [bu]) of corn, which is then
submerged in a current of dilute sulfurous acid solution at a temperature of about 52°C (125°F).
Total steeping time ranges from 28 to 48 hours. Each tank in the series holds corn that has been
steeping for a different length of time.
Corn that has steeped for the desired length of time is discharged from its tank for further
processing, and the tank is filled with fresh corn. New steeping liquid is added, along with recycled
water from other mill operations, to the tank with the "oldest" corn (in steep time). The liquid is
then passed through a series of tanks, moving each time to the tank holding the next "oldest" batch of
corn until the liquid reaches the newest batch of corn.
Water drained from the newest corn steep is discharged to evaporators as so-called "light
steepwater" containing about 6 percent of the original dry weight of grain. By dry-weight, the solids
1/95 Food And Agricultural Industry 9.9.7-1
-------
ENDOSPERM
c
Feed
RAW STARCH
CORN SYRUP**
Mixed Table
Syrups
Candles
Confectionery
IceCream
Shoe Polishes
CORN SUGAR
Infant Feeding
Diabetic Diet
Caramel Coloring
EDIBLE STARCH
Com Starch
Jeues
Candles
DEXTRIN
Mucilage
Glue
Textile Sizing
Food Sauces
Fireworks
GERM
I
OIL CAKE
(OR MEAL)
Cattle Feed
CRUDE CORN OIL
PLA
bsOAP
CERIN
SOLUBLE
STIC CORN OIL
RESIN Textile Sizing
Rubber ctoth Coloring
Substitutes
Erasers
Elastic
Heels REFINED CORN O
Tanning Mixtures
Brewing
Artificial Silk
BRAN
Cattle
Feed
INDUSTRIAL STARCH Salad Oils
Laundry Starch Cooking Oils
Textile Sizing Manufacture Medicinal Oils
Filler in Paper
Cosmetics
Explosives
Figure 9.9.7-1. Various uses of corn.
in the steepwater contain 35 to 45 percent protein and are worth recovering as feed supplements. The
steepwater is concentrated to 30 to 55 percent solids in multiple-effect evaporators. The resulting
steeping liquor, or heavy steepwater, is usually added to the fibrous milling residue, which is sold as
animal feed. Some steepwater may also be sold for use as a nutrient in fermentation processes.
The steeped corn passes through degerminating mills, which tear the kernel apart to free both
the germ and about half of the starch and gluten. The resultant pulpy material is pumped through
liquid cyclones to extract the germ from the mixture of fiber, starch, and gluten. The germ is
subsequently washed, dewatered, and dried; the oil extracted; and the spent germ sold as corn oil
meal or as part of corn gluten feed. More details on corn oil production are contained in
Section 9.11.1, "Vegetable Oil Processing".
The product slurry passes through a series of washing, grinding, and screening operations to
separate the starch and gluten from the fibrous material. The hulls are discharged to the feed house,
where they are dried for use in animal feeds.
At this point, the main product stream contains starch, gluten, and soluble organic materials.
The lower density gluten is separated from the starch by centrifugation, generally in 2 stages. A
high-quality gluten, of 60 to 70 percent protein and 1.0 to 1.5 percent solids, is then centrifuged,
dewatered, and dried for adding to animal feed. The centrifuge underflow containing the starch is
passed to starch washing filters to remove any residual gluten and solubles.
The pure starch slurry is now directed into 1 of 3 basic finishing operations, namely, ordinary
dry starch, modified starches, and corn syrup and sugar. In the production of ordinary dry starch,
the starch slurry is dewatered with vacuum filters or basket centrifuges. The discharged starch cake
has a moisture content of 35 to 42 percent and is further dewatered thermally in 1 of several types of
dryers. The dry starch is then packaged or shipped in bulk, or a portion may be kept for use in
making dextrin.
9.9.7-2
EMISSION FACTORS
1/95
-------
STEEPWATER
LIGHT STEEPWATER
PM-<-
>' (STARCH, GLUTEN, AND FIBROUS MATERIAL)
voc,
PM
A
HEAVY
STEEPWATER
CORN STEEP
LIQUOR
VOC,
PM
A
voc
A
GLUTEN
FEED DRYING
(SCO 3^2-007-63,-64)
CORN GL
UTEN
FEED
CORN OIL
MEAL
CRUDE
OIL
^.CORN OIL
MEAL
TO CORN OIL
REFINING
OPERATIONS
SLURRY
(STARCH, GLUTEN, AND SOLUBLE ORGANIC MATERIAL)
CORN GLUTEN MEAL
STARCH
SLURRY PURE
STARCH
SLURRY
ENZYMES
FINISHING OPERATIONS
HCI OR_,
ENZYME! ir
ETHANOL
CHEMICALS-n
Y
CORN SYRUP.
HIGH FRUCTOSE
CORN SYRUP
DEXTROSE
oc
PM
A
PM
A
FILTERS
>
t *•
MODIFIED STARCH
DRYING
(SCC 3-02-01 4-10, -11)
>
UNMOC
STAR
DRY
(SCC 302-0
VOC.
PM
A
' PM 1
MODIFIED *
CORN STARCH '
STORAGE
(SCC 3-02-01 4-07)
IFIED
CH
NG
14-12, -13)
PM
*
k UNMODIFIED
CORN STARCH
STORAGE
(SCC 3-02-01 4-07)
V
STARCH BULKLOADOUT
(SCC 3-02-01 4-08)
rc
DEXTRIN
COOKERS
J
DEXTRINS
PM
A
r -
STARCH BULK LOADOUT
(SCC 3-02-O1 4-08)
Figure 9.9.7-2. Corn wet milling process flow diagram.1"4
(Source Classification Codes in parentheses.)
1/95
Food And Agricultural Industry
9.9.7-3
-------
Modified starches are manufactured for various food and trade industries for which
unmodified starches are not suitable. For example, large quantities of modified starches go into the
manufacture of paper products as binding for the fiber. Modifying is accomplished in tanks that treat
the starch slurry with selected chemicals, such as hydrochloric acid, to produce acid-modified starch;
sodium hypochlorite, to produce oxidized starch; and ethylene oxide, to produce hydroxyethyl
starches. The treated starch is then washed, dried, and packaged for distribution.
Across the corn wet milling industry, about 80 percent of starch slurry goes to corn syrup,
sugar, and alcohol production. The relative amounts of starch slurry used for corn syrup, sugar, and
alcohol production vary widely among plants. Syrups and sugars are formed by hydrolyzing the
starch — partial hydrolysis resulting in corn syrup, and complete hydrolysis producing corn sugar.
The hydrolysis step can be accomplished using mineral acids, enzymes, or a combination of both.
The hydrblyzed product is then refined, which is the decolorization with activated carbon and the
removal of inorganic salt impurities with ion exchange resins. The refined syrup is concentrated to
the desired level in evaporators and is cooled for storage and shipping.
Dextrose production is quite similar to corn syrup production, the major difference being that
the hydrolysis process is allowed to go to completion. The hydrolyzed liquor is refined with activated
carbon and ion exchange resins, to remove color and inorganic salts, and the product stream is
concentrated by evaporation to the 70 to 75 percent solids range. After cooling, the liquor is
transferred to crystallizing vessels, where it is seeded with sugar crystals from previous batches. The
solution is held for several days while the contents are further cooled and the dextrose crystallizes.
After about 60 percent of the dextrose solids crystallize, they are removed from the liquid by
centrifuges, are dried, and are packed for shipment.
A smaller portion of the syrup refinery is devoted to the production of corn syrup solids. In
this operation, refined corn syrup is further concentrated by evaporation to a high dry substance level.
The syrup is then solidified by rapid cooling and subsequently milled to form an amorphous
crystalline product.
Ethanol is produced by the addition of enzymes to the pure starch slurry to hydrolyze the
starch to fermentable sugars. Following hydrolysis, yeast is added to initiate the fermentation
process. After about 2 days, approximately 90 percent of the starch is converted to ethanol. The
fermentation broth is transferred to a still where the ethanol (about 50 vol%) is distilled. Subsequent
distillation and treatment steps produce 95 percent, absolute, or denatured ethanol. More details on
this ethanol production process, emissions, and emission factors is contained in Section 6.21,
"Ethanol".
9.9.7.3 Emissions And Controls1'2'4"8
The diversity of operations in corn wet milling results in numerous and varied potential
sources of air pollution. It has been reported that the number of process emission points at a typical
plant is well over 100. The main pollutant of concern in grain storage and handling operations in
corn wet milling facilities is paniculate matter (PM). Organic emissions (e. g., hexane) from certain
operations at corn oil extraction facilities may also be significant. These organic emissions (and
related emissions from soybean processing) are discussed in Section 9.11.1, "Vegetable Oil
Processing". Other possible pollutants of concern are volatile organic compounds (VOC) and
combustion products from grain drying, sulfur dioxide (SO2) from corn wet milling operations, and
organic materials from starch production. The focus here is primarily on PM sources for grain
handling operations. Sources of VOC and SO2 are identified, although no data are available to
quantify emissions.
9.9.7-4 EMISSION FACTORS 1/95
-------
Emission sources associated with grain receiving, cleaning, and storage are similar in
character to those involved in all other grain elevator operations, and other PM sources are
comparable to those found in other grain processing plants as described in Section 9.9.1, "Grain
Elevators And Processes". However, corn wet milling operations differ from other processes in that
they are also sources of SO2 and VOC emissions, as described below.
The corn wet milling process uses about 1.1 to 2.0 kg of SO2 per megagram (Mg) of corn
(0.06 to 0.11 Ib/bu). The SO2 is dissolved in process waters, but its pungent odor is present in the
slurries, necessitating the enclosing and venting of the process equipment. Vents can be wet-scrubbed
with an alkaline solution to recover the SO2 before the exhaust gas is discharged to the atmosphere.
The most significant source of VOC emissions, and also a source of PM emissions, from corn wet
milling is the exhaust from the different drying processes. The starch modification procedures also
may be sources of acid mists and VOC emissions, but data are insufficient to characterize or to
quantify these emissions.
Dryer exhausts exhibit problems with odor and blue haze (opacity). Germ dryers emit a
toasted smell that is not considered objectionable in most areas. Gluten dryer exhausts do not create
odor or visible emission problems if the drying temperature does not exceed 427°C (800°F). Higher
temperatures promote hot smoldering areas in the drying equipment, creating a burnt odor and a blue-
brown haze. Feed drying, where steepwater is present, results in environmentally unacceptable odor
if the drying temperature exceeds 427°C (800°F). Blue haze formation is a concern when drying
temperatures are elevated. These exhausts contain VOC with acrid odors, such as acetic acid and
acetaldehyde. Rancid odors can come from butyric and valeric acids, and fruity smells emanate from
many of the aldehydes present.
The objectionable odors indicative of VOC emissions from process dryers have been reduced
to commercially acceptable levels with ionizing wet-collectors, in which particles are charged
electrostatically with up to 30,000 volts. An alkaline wash is necessary before and after the ionizing
sections. Another approach to odor/VOC control is thermal oxidation at approximately 750°C
(1382°F) for 0.5 seconds, followed by some form of heat recovery. This hot exhaust can be used as
the heat source for other dryers or for generating steam in a boiler specifically designed for this type
of operation. Incineration can be accomplished in conventional boilers by routing the dryer exhaust
gases to the primary air intake. The limitations of incineration are potential fouling of the boiler air
intake system with PM and derated boiler capacity because of low oxygen content. These limitations
severely restrict this practice. At least 1 facility has attempted to use a regenerative system, in which
dampers divert the gases across ceramic fill where exhaust heats the fumes to be incinerated.
Incinerator size can be reduced 20 to 40 percent when some of the dryer exhaust is fed back into the
dryer furnace. From 60 to 80 percent of the dryer exhaust may be recycled by chilling it to condense
the water before recycling.
The PM emissions generated from grain receiving, handling, and processing operations at
corn wet milling facilities can be controlled either by process modifications designed to prevent or
inhibit emissions or by application of capture collection systems.
The fugitive emissions from grain handling operations generated by mechanical energy
imparted to the dust, both by the operations themselves and by local air currents in the vicinity of the
operations, can be controlled by modifying the process or facility to limit the generation of fugitive
dust. The primary preventive measures used by facilities are construction and sealing practices that
limit the effect of air currents, and minimizing grain free fall distances and grain velocities during
handling and transfer. Some recommended construction and sealing practices that minimize emissions
are: (1) enclosing the receiving area to the extent practicable; (2) specifying dust-tight cleaning and
1/95 Food And Agricultural Industry 9.9.7-5
-------
processing equipment; (3) using lip-type shaft seals at bearings on conveyor and other equipment
housings; (4) using flanged inlets and outlets on all spouting, transitions, and miscellaneous hoppers;
and (5) fully enclosing and sealing all areas in contact with products handled.
While preventive measures can reduce emissions, most facilities also require ventilation or
capture/collection systems to reduce emissions to acceptable levels. Milling operations generally are
ventilated, and some facilities use hood systems on all handling and transfer operations. The control
devices typically used in conjunction with capture systems for grain handling and processing
operations are cyclones (or mechanical collectors) and fabric filters. Both of these systems can
achieve acceptable levels of control for many grain handling and processing sources. However, even
though cyclone collectors can achieve acceptable performance in some scenarios, and fabric filters are
highly efficient, both devices are subject to failure if not properly operated and maintained.
Ventilation system malfunction, of course, can lead to increased emissions at the source.
Table 9.9.7-1 shows the filterable PM emission factors developed from the available data on
several source/control combinations. Table 9.9.7-2 shows potential sources of VOC and SO2,
although no data are available to characterize these emissions.
9.9.7-6 EMISSION FACTORS 1/95
-------
Table 9.9.7-1 (Metric And English Units). PARTICULATE MATTER EMISSION FACTORS
FOR CORN WET MILLING OPERATIONS4
EMISSION FACTOR RATING: E
Emission Source
Grain receiving0 (trucks)
(SCC 3-02-007-51)
Grain handling0 (legs, belts, etc.)
(SCC 3-02-007-52)
Grain cleaning**
(SCC 3-02-007-53)
Grain cleaningd
(SCC 3-02-007-53)
Starch storage bine
(SCC 3-02-014-07)
Starch bulk loadoutf
(SCC 3-02-014-08)
Gluten feed drying
Direct-fired rotary dryers8
(SCC 3-02-007-63)
Indirect-fired rotary dryers8
(SCC 3-02-007-64)
Starch drying
Flash dryers^
(SCC 3-02-014-10, -12)
Spray dryersk
(SCC 3-02-014-11, -13)
Gluten drying
Direct-fired rotary dryers8
(SCC 3-02-007-68)
Indirect-fired rotary dryers8
(SCC 3-02-007-69)
Fiber drying
(SCC 3-02-007-67)
Germ drying
(SCC 3-02-007-66)
Dextrose drying
(SCC 3-02-007-70)
Degerminating mills
(SCC 3-02-007-65)
Milling
(SCC 3-O2-007-56)
Type Of Control
Fabric filter
None
None
Cyclone
Fabric filter
Fabric filter
Product recovery
cyclone
Product recovery
cycloneh
Wet scrubber
Fabric filter
Product recovery
cyclone
Product recovery
cyclone
ND
ND
ND
ND
ND
Filterable PMb
kg/Mg
0.016
0.43
0.82
0.086
0.0007
0.00025
0.13
0.25
0.29
0.080
0.13
0.25
ND
ND
ND
ND
ND
Ib/ton
0.033
0.87
1.6
0.17
0.0014
0.00049
0.27
0.49
0.59
0.16
0.27
0.49
ND
ND
ND
ND
ND
1/95
Food And Agricultural Industry
9.9.7-7
-------
Table 9.9.7-1 (cont.).
a For grain transfer and handling operations, factors are for an aspirated collection system of 1 or
more capture hoods ducted to a paniculate collection device. Because of natural removal processes,
uncontrolled emissions may be overestimated. ND = no data. SCC = Source Classification Code.
b Emission factors based on weight of PM, regardless of size, per unit weight of corn throughput
unless noted.
c Assumed to be similar to country grain elevators (see Section 9.9.1).
d Assumed to be similar to country grain elevators (see Section 9.9.1). If 2 cleaning stages are used,
emission factor should be doubled.
e Reference 9.
f Reference 9. Emission factor based on weight of PM per unit weight of starch loaded.
g Reference 10. Type of material dried not specified, but expected to be gluten meal or gluten feed.
Emission factor based on weight of PM, regardless of size, per unit weight of gluten meal or gluten
feed produced.
h Includes data for 4 (out of 9) dryers known to be vented through product recovery cyclones, and
other systems are expected to have such cyclones. Emission factor based on weight of PM,
regardless of size, per unit weight of gluten meal or gluten feed produced.
j References 11-13. EMISSION FACTOR RATING: D. Type of material dried is starch, but
whether the starch is modified or unmodified is not known. Emission factor based on weight of
PM, regardless of size, per unit weight of starch produced.
k Reference 14. Type of material dried is starch, but whether the starch is modified or unmodified is
not known. Emission factor based on weight of PM, regardless of size, per unit weight of starch
produced.
Table 9.9.7-2 (Metric And English Units). EMISSION FACTORS FOR CORN WET MILLING
OPERATIONS
Emission Source
Steeping
(SCC 3-02-007-61)
Evaporators
(SCC 3-02-007-62)
Gluten feed drying
(SCC 3-02-007-63, -64)
Germ drying
(SCC 3-02-O07-66)
Fiber drying
(SCC 3-02-007-67)
Gluten drying
(SCC 3-02-007-68, -69)
Starch drying
(SCC 3-02-014-10, -11,
-12, -13)
Dextrose drying
(SCC 3-02-007-70)
Oil expelling/extraction
(SCC 3-02-019-16)
Type Of
Control
ND
ND
ND
ND
ND
ND
ND
ND
ND
VOC
kg/Mg
ND
ND
ND
ND
ND
ND
ND
ND
ND
Ib/ton
ND
ND
ND
ND
ND
ND
ND
ND
ND
SO2
kg/Mg
ND
ND
ND
ND
ND
ND
ND
ND
ND
Ib/ton
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND = no data. SCC = Source Classification Code.
9.9.7-8
EMISSION FACTORS
1/95
-------
References For Section 9.9.7
1. Written communication from M. Kosse, Corn Refiners Association, Inc., Alexandria, VA, to
D. Safriet, U. S. Environmental Protection Agency, Research Triangle Park, NC, January 18,
1994.
2. L. J. Shannon, et al., Emissions Control In The Grain And Feed Industry, Volume I:
Engineering And Cost Study, EPA-450/3-73-003a, U.S. Environmental Protection Agency,
Research Triangle Park, NC, December 1973.
3. G. F. Spraque and J. W. Dudley, Corn And Corn Improvement, Third Edition, American
Society Of Agronomy, Crop Science Society Of America, and Soil Science Society Of
America, Madison, WI, 1988.
4. S. A. Watson and P. E. Ramstad, Corn Chemistry And Technology, American Association of
Cereal Chemists, St. Paul, MN, 1987.
5. American Feed Manufacturers Association, Arlington, VA, Feed Technology, 1985.
6. D. Wallace, "Grain Handling And Processing", Air Pollution Engineering Manual, Van
Nostrand Reinhold, NY, 1992.
7. H. D. Wardlaw, Jr., et al., Dust Suppression Results With Mineral Oil Applications For Corn
And Milo, Transactions Of The American Society Of Agricultural Engineers, Saint Joseph,
MS, 1989.
8. A. V. Myasnihora, et al., Handbook Of Food Products — Grain And Its Products, Israel
Program for Scientific Translations, Jerusalem, Israel, 1969.
9. Starch Storage Bin And Loading System, Report No. 33402, prepared by Beling Consultants,
Moline, IL, November 1992.
10. Source Category Survey: Animal Feed Dryers, EPA-450/3-81-017, U. S. Environmental
Protection Agency, Research Triangle Park, NC, December 1981.
11. Starch Flash Dryer, Report No. 33405, prepared by Beling Consultants, Moline, IL,
February 1993.
12. No. 4 Starch Flash Dryer, Report No. 1-7231-1, prepared by The Almega Corporation,
Bensenville, IL, May 1993.
13. No. 1 Starch Flash Dryer, Report No. 86-177-3, prepared by Burns & McDonnell, Kansas
City, MO, August 1986.
14. Starch Spray Dryer, Report No. 21511, prepared by Mostardi-PIatt Associates, Inc.,
Bensenville, IL, August 1992.
1/95 Food And Agricultural Industry 9.9.7-9
-------
9.10 Confectionery Products
9.10.1 Sugar Processing
9.10.2 Salted And Roasted Nuts and Seeds
1/95 Food And Agricultural Industries 9.10-1
-------
9.10.1 Sugar Processing
9.10.1.1 Cane Sugar Processing
9.10.1.2 Beet Sugar Processing
1/95 Food And Agricultural Industries 9.10.1-1
-------
9.10.1.1 Cane Sugar Processing
9.10.1.1.1 General1'3
Sugar cane is burned in the field prior to harvesting to remove unwanted foliage as well as to
control rodents and insects. Harvesting is done by hand or, where possible, by mechanical means.
After harvesting, the cane goes through a series of processing steps for conversion to the final
sugar product. It is first washed to remove dirt and trash, then crushed and shredded to reduce the
size of the stalks. The juice is next extracted by 1 of 2 methods, milling or diffusion. In milling, the
cane is pressed between heavy rollers to squeeze out the juice; in diffusion, the sugar is leached out by
water and thin juices. The raw sugar then goes through a series of operations including clarification,
evaporation, and crystallization in order to produce the final product. The fibrous residue remaining
after sugar extraction is called bagasse.
All mills fire some or all of their bagasse in boilers to provide power necessary in their milling
operation. Some, having more bagasse than can be utilized internally, sell the remainder for use in the
manufacture of various chemicals such as furfural.
9.10.1.1.2 Emissions2'3
The largest sources of emissions from sugar cane processing are the openfield burning in the
harvesting of the crop, and the burning of bagasse as fuel. In the various processes of crushing,
evaporation, and crystallization, relatively small quantities of particulates are emitted. Emission factors
for sugar cane field burning are shown in Table 2.5-2. Emission factors for bagasse firing in boilers
are included in Section 1.8.
References For Section 9.10.1.1
1. "Sugar Cane," In: Kirk-Othmer Encyclopedia Of Chemical Technology, Vol. IX, New York,
John Wiley and Sons, Inc., 1964.
2. E. F. Darley, "Air Pollution Emissions From Burning Sugar Cane And Pineapple From
Hawaii", In: Air Pollution From Forest And Agricultural Burning, Statewide Air Pollution
Research Center, University of California, Riverside, California, Prepared for the U. S.
Environmental Protection Agency, Research Triangle Park, NC, under Grant No. R800711,
August 1974.
3. Background Information For Establishment Of National Standards Of Performance For New
Sources, Raw Cane Sugar Industry, Environmental Engineering, Inc., Gainesville, FL, Prepared
for the U. S. Environmental Protection Agency, Research Triangle Park, NC, under Contract
No. CPA 70-142, Task Order 9c, July 15, 1971.
4/76 (Reformatted 1/95) Food And Agricultural Industries 9.10.1.1-1
-------
9.10.1.2 Sugarbeet Processing
9.10.1.2.1 General1'2
Sugarbeet processing is the production of sugar (sucrose) from sugarbeets. Byproducts of
sugarbeet processing include pulp and molasses. Most of the molasses produced is processed further to
remove the remaining sucrose. The pulp and most of the remaining molasses are mixed together, dried,
and sold as livestock feed.
9.10.1.2.2 Process Description1-4
Figures 9.10.1.2-1 and 9.10.1.2-2 are flow diagrams for a typical sugarbeet processing plant.
Figure 9.10.1.2-1 shows preprocessing and livestock feed production operations, and Figure 9.10.1.2-2
shows the beet sugar production operations. Mechanically harvested sugarbeets are shipped to processing
plants, where they are typically received by high-speed conveying and screening systems. The screening
systems remove loose dirt from the beets and pinch the beet tops and leaves from the beet roots. The
conveyors transport the beets to storage areas and then to the final cleaning and trash removal operations
that precede the processing operations. The beets are usually conveyed to the final cleaning phase using
flumes, which use water to both move and clean the beets. Although most plants use flumes, some plants
use dry conveyors in the final cleaning stage. The disadvantage of flume conveying is that some sugar
leaches into the flume water from damaged surfaces of the beets. The flumes carry the beets to the beet
feeder, which regulates the flow of beets through the system and prevents stoppages in the system. From
the feeder, the flumes carry the beets through several cleaning devices, which may include rock catchers,
sand separators, magnetic metal separators, water spray nozzles, and trash catchers. After cleaning, the
beets are separated from the water, usually with a beet wheel, and are transported by drag chain, chain
and bucket elevator, inclined belt conveyor, or beet pump to the processing operations.
Sugarbeet processing operations comprise several steps, including diffusion, juice purification,
evaporation, crystallization, dried-pulp manufacture, and sugar recovery from molasses. Descriptions of
these operations are presented in the following paragraphs.
Prior to removal of the sucrose from the beet by diffusion, the cleaned and washed beets are sliced
into long, thin strips, called cossettes. The cossettes are conveyed to continuous diffusers, in which hot
water is used to extract sucrose from the cossettes. In one diffuser design, the diffuser is slanted upwards
and conveys the cossettes up the slope as water is introduced at the top of the diffuser and flows
countercurrent to the cossettes. The water temperature in the diffuser is typically maintained between 50°
and 80°C (122° and 176°F). This temperature is dependant on several factors, including the
denaturization temperature of the cossettes, the thermal behavior of the beet cell wall, potential enzymatic
reactions, bacterial activity, and pressability of the beet pulp. Formalin, a 40 percent solution of
formaldehyde, was sometimes added to the diffuser water as a disinfectant but is not used at the present
time. Sulfur dioxide, chlorine, ammonium bisulfite, or commercial FDA-approved biocides are used as
disinfectants. The sugar-enriched water that flows from the outlet of the diffuser is called raw juice and
contains between 10 and 15 percent sugar. This raw juice proceeds to the juice purification operations.
The processed cossettes, or pulp, leaving the diffuser are conveyed to the dried-pulp manufacture
operations.
3/97 Food And Agricultural Industry 9.10.1.2-1
-------
0-
FINAL CLEANING
AND
TRASH REMOVAL
11
STORAGE
/ 1
CONVEYING
AND
SCREENING
1 '
CD
Q.
Q.
CO
1 i
Z
HARVESTI
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LIVESTOCK FEED
STORAGE AND
SHIPPING
ii
PELLET COOLER
(3-02-016-16)
1 1
PELLETIZING
(3-02-016-12)
1 1
°9o5
I
I
•4-J
,, u
SUCERS
sugarbeet processing
03
" I 1
DIFFUSER
i
1
* 1 1
PULP
PRESSES
J ,
:
RAW JUICE TO SLK
1 PRODUCTION
T OPERATIONS
feed production operat
ode in parentheses.)
BEET PULP
.10.1.2-1. Preprocessing and livestock
(Source Classification C
z *°
50 3
1|§ S
UJ11-^
I1S
-------
c,
t»o
'55
f>
3/97
Food And Agricultural Industry
9.10.1.2-3
-------
In the juice purification stage, non-sucrose impurities in the raw juice are removed so that the pure
sucrose can be crystallized. First, the juice passes through screens to remove any small cossette particles.
Then the mixture is heated to 80° to 85°C (176° to 185°F) and proceeds to the first carbonation tank. In
some processes, the juice from the screen passes through a pre-limer, heater, and main limer prior to the
first carbonation tank. In the first carbonation tank, milk of lime [Ca(OH)2] is added to the mixture to
adsorb or adhere to the impurities in the mixture, and carbon dioxide (C02) gas is bubbled through the
mixture to precipitate the lime as insoluble calcium carbonate crystals. Lime kilns are used to produce the
C02 and lime used in carbonation; the lime is converted to milk of lime in a lime slaker. The small,
insoluble crystals (produced during carbonation) settle out in a clarifier, after which the juice is again
treated with C02 (in the second carbonation tank) to remove the remaining lime and impurities. The pH
of the juice is lower during this second carbonation, causing large, easily filterable, calcium carbonate
crystals to form. After filtration, a small amount of sulfur dioxide (S02) is added to the juice to inhibit
reactions that lead to darkening of the juice. Most facilities purchase S02 as a liquid but a few facilities
produce S02 by burning elemental sulfur in a sulfur stove. Following the addition of S02, the juice
(known as thin juice) proceeds to the evaporators.
The evaporation process, which increases the sucrose concentration in the juice by removing
water, is typically performed in a series of five evaporators. Steam from large boilers is used to heat the
first evaporator, and the steam from the water evaporated in the first evaporator is used to heat the second
evaporator. This transfer of heat continues through the five evaporators, and as the temperature decreases
(due to heat loss) from evaporator to evaporator, the pressure inside each evaporator is also decreased,
allowing the juice to boil at the lower temperatures provided in each subsequent evaporator. Some steam
is released from the first three evaporators, and this steam is used as a heat source for various process
heaters throughout the plant. After evaporation, the percentage of sucrose in the "thick juice" is
50-65 percent. Crystalline sugars, produced later in the process, are added to the juice and dissolved in
the high melter. This mixture is then filtered, yielding a clear liquid known as standard liquor, which
proceeds to the crystallization operation.
Sugar is crystallized by low-temperature pan boiling. The standard liquor is boiled in vacuum
pans until it becomes supersaturated. To begin crystal formation, the liquor is either "shocked" using a
small quantity of powdered sugar or is "seeded" by adding a mixture of finely milled sugar and isopropyl
alcohol. The seed crystals are carefully grown through control of the vacuum, temperature, feed-liquor
additions, and steam. When the crystals reach the desired size, the mixture of liquor and crystals, known
as massecuite or fillmass, is discharged to the mixer. From the mixer, the massecuite is poured into high-
speed centrifugals, in which the liquid is centrifuged into the outer shell, and the crystals are left in the
inner centrifugal basket. The sugar crystals are then washed with pure hot water and are sent to the
granulator, which is a combination rotary drum dryer and cooler. Some facilities have separate sugar
dryers and coolers, which are collectively called granulators. The wash water, which contains a small
quantity of sucrose, is pumped to the vacuum pans for processing. After cooling, the sugar is screened
and then either packaged or stored in large bins for future packaging.
The liquid that was separated from the sugar crystals in the centrifugals is called syrup. This
syrup serves as feed liquor for the "second boiling" and is introduced back into the vacuum pans along
with standard liquor and recycled wash water. The process is repeated once again, resulting in the
production of molasses, which can be further desugarized using an ion exchange process called deep
molasses desugarization. Molasses that is not desugarized can be used in the production of livestock feed
or for other purposes.
Wet pulp from the diffusion process is another product of sugarbeet processing. The pulp is first
pressed, typically in horizontal double-screw presses, to reduce the moisture content from about 95 percent
9.10.1.2-4 EMISSION FACTORS 3/97
-------
to about 75 percent. The water removed by the presses is collected and used as diffusion water. After
pressing, molasses is added to the pulp, which is then dried in a direct-fired horizontal rotating drum
known as a pulp dryer. The pulp dryer, which can be fired by oil, natural gas, or coal, typically provides
entrance temperatures between 482° and 927°C (900° and 1700°F). As the pulp is dried, the gas
temperature decreases and the pulp temperature increases. The exit temperature of the flue gas is typically
between 88° and 138°C (190° and 280°F). The resulting product is usually pelletized, cooled, and sold as
livestock feed.
9.10.1.2.3 Emissions And Controlsl • 3~4
Particulate matter (PM), combustion products, and volatile organic compounds (VOC) are the
primary pollutants emitted from the sugarbeet processing industry. The pulp dryers, sugar granulators and
coolers, sugar conveying and sacking equipment, lime kilns and handling equipment, carbonation tanks,
sulfur stoves, evaporators, and boilers, as well as several fugitive sources are potential emission sources.
Potential emissions from boilers are addressed in AP-42 Sections 1.1 through 1.4 (Combustion) and those
from lime kilns are addressed in AP-42 Section 11.17, Lime Manufacturing. Potential sources of PM
emissions include the pulp dryer, sugar granulators and coolers, sugar conveying and sacking equipment,
sulfur stove, and fugitive sources. Fugitive sources include unpaved roads, coal handling, and pulp
loading operations. Although most facilities purchase S02, a few facilities still use sulfur stoves. The
sulfur stove is a potential source of SO2 emissions, and the pulp dryers may be a potential source of
nitrogen oxides (NOX), S02, C02, carbon monoxide (CO), and VOC. Evaporators may be a potential
source of C02, ammonia (NH^, S02, and VOC emissions from the juice. However, only the first three
of five evaporators (in a typical five-stage system) release exhaust gases, and the gases are used as a heat
source for various process heaters before release to the atmosphere. Emissions from carbonation tanks are
primarily water vapor but contain small quantities of NH3, VOC, and may also include C02 and other
combustion gases from the lime kiln. There are no emission test data available for ammonia emissions
from carbonation tanks.
Particulate matter emissions from pulp dryers are typically controlled by a cyclone or multiclone
system, sometimes followed by a secondary device such as a wet scrubber or fabric filter. Particulate
matter emissions from granulators are typically controlled with wet scrubbers, and PM emissions from
sugar conveying and sacking as well as lime dust handling operations are controlled by hood systems that
duct the emissions to fabric filtration systems. Emissions from carbonation tanks and evaporators are not
typically controlled.
Table 9.10.1.2-1 presents emission factors for filterable PM, PM-10, and condensible PM
emissions from sugarbeet processing operations. Table 9.10.1.2-2 presents emission factors for volatile
organic compounds (VOC), methane, NOX, S02, CO, and CO2 emissions from sugarbeet processing
operations, and Tables 9.10.1.2-3 and 9.10.1.2-4 present emission factors for organic pollutants emitted
from coal-fired dryers, carbonation tanks, and first evaporators.
3/97 Food And Agricultural Industry 9.10.1.2-5
-------
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Table 9.10.1.2-2. EMISSION FACTORS FOR VOC, METHANE, AND INORGANIC
POLLUTANT EMISSIONS FROM SUGARBEET PROCESSING OPERATIONS3
EMISSION FACTOR RATING: D
Source
Coal-fired pulp dryerc
(SCC 3-02-016-01)
Natural gas-fired pulp dryerc
(SCC 3-02-016-08)
Fuel oil-fired pulp dryerc
(SCC 3-02-016-05)
First evaporator
(SCC 3-02-016-41)
Sulfur stove
(SCC 3-02-0 16-31)
First carbonation tank
(SCC 3-02-016-21)
Second carbonation tank
(SCC 3-02-01 6-22)
Ib/ton
vocb
1.2d
ND
0.1 lJ
ND
ND
ND
ND
Methane
ND
ND
0.028J
ND
ND
ND
ND
NOY
0.66e
ND
0.60J
ND
ND
ND
ND
S0?
0.79f
ND
1.0k
ND
ND
ND
ND
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ND
l.OJ
ND
ND
ND
ND
CO,
3708
156h
430m
ND
ND
ND
ND
a Emission factor units are Ib/ton of pressed wet pulp to the dryer, unless noted. Factors represent
uncontrolled emissions unless noted. To convert from Ib/ton to kg/Mg, multiply by 0.5.
SCC = Source Classification Code. ND = no data.
b Volatile organic compounds as methane.
c Data for pulp dryers equipped with cyclones, multiclones, wet scrubbers, or a combination of these
control technologies are averaged together because these control technologies are not specifically
designed to control VOC, methane, NOX, SO2, CO, or C02 emissions.
d Reference 19.
e References 16,19.
f References 7,19.
8 References 7,13,16-17,19,21. EMISSION FACTOR RATING: B.
h References 8-12,22-23,25. EMISSION FACTOR RATING: C.
J Reference 4.
k References 14-15.
m References 4-6,14,24. EMISSION FACTOR RATING: C.
9.10.1.2-8
EMISSION FACTORS
3/97
-------
Table 9.10.1.2-3. EMISSION FACTORS FOR ORGANIC POLLUTANT EMISSIONS
FROM PULP DRYERS3
EMISSION FACTOR RATING: E
Source
Coal-fired pulp dryer with wet
scrubber
(SCC 3-02-016-01)
Pollutant
CASRN
75-07-0
107-02-8
123-73-9
50-00-0
91-57-6
88-75-5
95-48-7
105-67-9
106-44-5
100-02-7
208-96-8
100-52-7
65-85-0
100-51-6
117-81-7
84-74-2
132-64-9
84-66-2
91-20-3
98-95-3
85-01-8
108-95-2
Name
Acetaldehyde
Acrolein
Crotonaldehyde
Formaldehyde
2-methylnaphthalene
2-nitrophenol
2-methylphenol
2,4-dimethylphenol
4-methylphenol
4-nitrophenol
Acenaphthylene
Benzaldehyde
Benzole acid
Benzyl alcohol
Bis(2-ethylhexyl)phthalate
Di-n-butylphthalate
Dibenzofuran
Diethylphthalate
Naphthalene
Nitrobenzene
Phenanthrene
Phenol
Emission
Factor,
Ib/ton
0.015
0.0076
0.0020
0.0071
1.7xlO-5
0.00018
3.4xlO-5
2.5xlO-5
0.00013
0.00014
1.7xlO'6
0.0014
0.0028
7.1xlQ-5
0.0015
5.2xlO-5
l.lxlO'5
9.8xlQ-6
0.00011
1.9xlO-5
1.2xlO-5
0.00032
a Reference 3. Emission factor units are Ib/ton of pressed wet pulp to the dryer. To convert from Ib/ton
to kg/Mg, multiply by 0.5. SCC = Source Classification Code. CASRN = Chemical Abstracts Service
Registry Number.
3/97
Food And Agricultural Industry
9.10.1.2-9
-------
Table 9.10.1.2-4. EMISSION FACTORS FOR ORGANIC POLLUTANT EMISSIONS
FROM CARBONATION TANKS AND EVAPORATORS3
Source
First carbonation tankb
(SCC 3-02-016-21)
Second carbonation tankb
(SCC 3-02-016-22)
First evaporator0
(SCC 3-02-016-41)
Pollutant
CASRN
91-57-6
51-28-5
106-44-5
83-32-9
100-52-7
65-85-0
100-51-6
117-81-7
91-20-3
85-01-8
108-95-2
75-07-0
107-02-8
123-73-9
50-00-0
75-07-0
107-02-8
123-73-9
50-00-0
106-44-5
100-52-7
65-85-0
100-51-6
117-81-7
84-74-2
132-64-9
84-66-2
78-59-1
91-20-3
85-01-8
108-95-2
110-86-1
Name
2-methylnaphthalene
2,4-dinitrophenol
4-methylphenol
Acenaphthene
Benzaldehyde
Benzoic acid
Benzyl alcohol
Bis(2-ethylhexyl) phthalate
Naphthalene
Phenanthrene
Phenol
Acetaldehyde
Acrolein
Crotonaldehyde
Formaldehyde
Acetaldehyde
Acrolein
Crotonaldehyde
Formaldehyde
4-methylphenol
Benzaldehyde
Benzoic acid
Benzyl alcohol
Bis(2-ethylhexyl)phthalate
Di-n-butylphthalate
Dibenzofuran
Diethylphthalate
Isophorone
Naphthalene
Phenanthrene
Phenol
Pyridine
Emission Factor,
Ih/l.OOOgal
5.1xlO-7
ND
6.6xlO-7
ND
l.lxlO'4
8.4xlO-6
5.0xlO-6
1.2xlQ-5
2.0xlO-6
1.4xlQ-6
1.3xlO-6
0.0043
2.4xlO'4
3.0xlO~5
1.6xlQ-5
6.7xlO-5
4.2xlO-7
1.4xlQ-7
7.0xlO-7
ND
2.2xlO-6
ND
l.SxlO'7
3.7xlO-7
1.1 xlO-9
ND
ND
ND
2.5xlQ-8
1.6xlO-8
1.2xlQ-8
3.4xlO-8
EMISSION
FACTOR
RATING
D
D
D
D
D
D
D
D
D
D
D
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
a Reference 3. SCC = Source Classification Code. CASRN = Chemical Abstracts Service Registry
Number. ND = no data.
b Emission factor units are Ib per 1,000 gallons of raw juice produced.
c Emission factor units are Ib per 1,000 gallons of thin juice produced.
9.10.1.2-10
EMISSION FACTORS
3/97
-------
REFERENCES FOR SECTION 9.10.1.2
1. R.A. McGinnis, Beet-Sugar Technology, Third Edition, Beet Sugar Development Foundation, Fort
Collins, CO, 1982.
2. The Beet Sugar Story, United States Beet Sugar Association, Washington, D.C., 1959.
3. Particulate, Aldehyde, And Semi-Volatile Organic Compound (SVOC) Testing Report For The Pulp
Dryer Stacks, 1st And 2nd Carbonation Tank Vents, And The Evaporator Heater Vents, The
Amalgamated Sugar Company, Nampa, ID, May 14, 1993.
4. Emission Performance Testing Of Four Boilers, Three Dryers, And One Cooler-Holly Sugar
Corporation, Santa Maria, California, Western Environmental Services, Redondo Beach, CA,
June 1991.
5. Results Of A Source Emission Compliance Test At Southern Minnesota Beet Sugar Cooperative,
Renville, Minnesota, MMT Environmental, Inc., St. Paul, MN, January 21, 1988.
6. Results Of An Emission Compliance Test On The North Dryer #2 At Southern Minnesota Beet
Sugar Cooperative, Renville, Minnesota, MMT Environmental, Inc., St. Paul, MN,
December 14, 1988.
7. Results Of A Source Emission Compliance Test At Minn-Dak Farmers Cooperative, Wahpeton,
North Dakota, MMT Environmental, Inc., St. Paul, MN, November 1, 1983.
8. Particulate Emission Testing Performed For Monitor Bay Sugar Company, Bay City, Michigan, On
The Pulp Dryer 3 Exhaust, Network Environmental, Inc., Grand Rapids, MI, October 12, 1992.
9. Particulate Emission Testing Performed For Monitor Bay Sugar Company, Bay City, Michigan, On
The Pulp Dryer 2 Exhaust, Network Environmental, Inc., Grand Rapids, MI, October 13, 1992.
10. Particulate Emission Testing Performed For Monitor Bay Sugar Company, Bay City, Michigan, On
The Pulp Dryer 1 Exhaust, Network Environmental, Inc., Grand Rapids, MI, October 14, 1992.
11. Emissions Survey Conducted At Western Sugar Company's Billings, Montana, Production Facility,
American Environmental Testing Company, Inc., December 1988.
12. EPA Method 5 Particulate Emissions Tests Conducted On Western Sugar's Boiler And Pulp Dryer
Stacks Located In Billings, Montana, American Environmental Testing Company, Inc.,
January 1990.
13. .Report On Compliance Testing Performed At Western Sugar Company Pulp Dryer, Scottsbluff, NE,
Clean Air Engineering, Palatine, IL, January 12, 1990.
3/97 Food And Agricultural Industry 9.10.1.2-11
-------
14. Emission Measurement Test Report Of C.E. Boilers, Union Boilers, And Pulp Dryers-Permit
Compliance ForSO2, Particulate, And PM-10 With Back-Half Emissions-Holly Sugar
Corporation, Montana Division, The Emission Measurement Group, Inc., Englewood, CO,
November 16, 1993.
15. .Report To Great Lakes Sugar Company On Stack Particulate Samples Collected On The Pulp Drier
At Fremont, Ohio, Affiliated Environmental Services, Inc., Sandusky, OH, December 8, 1992.
16. Results Of The February 22-24, 1994, Air Emission Compliance Testing Of Process Sources At The
American Crystal Sugar East Grand Forks Plant, Interpoll Laboratories, Inc., Circle Pines, MN,
March 21, 1994.
17. Results Of The January 28-31, 1992, Particulate Emission Tests, South Pulp Dryer-American
Crystal Sugar Company, Moorehead, Minnesota, Bay West, Inc., St. Paul, MN, March 26, 1992.
18. Results Of A Source Emission Compliance Test On The Sugar Cooler Stack At American Crystal
Sugar Company, Crookston, Minnesota, March 11, 1993, Twin City Testing Corporation,
St. Paul, MN, April 16, 1993.
19. Results Of The November 9-11, 1993, Air Emission Testing Of Process Sources At The American
Crystal Sugar East Grand Forks Plant, Interpoll Laboratories, Inc., Circle Pines, MN,
December 3, 1993.
20. Results Of The November 14 And 15, 1990, State Particulate Emission Compliance Test On The
Sugar Cooler And Sugar Granulator At The ACS Moorehead Plant, Interpoll Laboratories, Inc.,
Circle Pines, MN, December 11, 1990.
21. Unit Nos. 1 And 2 Pulp Dryer Stacks Emission Testing Results For The February 22-26, 1993,
Testing Of Particulate Conducted At The American Crystal Sugar Company, Crookston,
Minnesota, Bay West, Inc., St. Paul, MN, April 15, 1993.
22. Particulate Emission Study For Michigan Sugar Company, Caro, Michigan, Swanson
Environmental, Inc., Farmington Hills, MI, December 14, 1989.
23. Particulate Emission Study For Michigan Sugar Company, Carrollton, Michigan, Swanson
Environmental, Inc., Farmington Hills, MI, November 1989.
24. Particulate Emission Study-Michigan Sugar Company, CrosweU, Michigan, Swanson
Environmental, Inc., Farmington Hills, MI, November 19, 1990.
25. Emissions Survey Conducted At Western Sugar Company, Scottsbluff, Nebraska, American
Environmental Testing, Inc. Spanish Fork, UT, January 10, 1995.
9.10.1.2-12 EMISSION FACTORS 3/97
-------
9.10.2 Salted And Roasted Nuts And Seeds
This industry encompasses a range of edible nuts and seeds processed primarily for human
consumption. The salted and roasted nuts and seeds industry primarily includes establishments that
produce salted, roasted, dried, cooked, or canned nuts, or that process grains and seeds for snack use.
This industry does not encompass facilities that manufacture candy-coated nuts or those that
manufacture peanut butter. The overall production of finished salted and roasted nuts and seeds has
two primary components. Typically, nuts undergo post harvest processing such as hulling and
shelling, either by the farmer on the farm, or by contractor companies either on the farm or at
facilities near the farm, called crop preparation service facilities. The shelled nuts or seeds are
shipped to food processing plants to produce the final product.
Many of the post-harvest operations and processes are common to most of the nuts and seeds,
including field harvesting and loading, unloading, precleaning, drying, screening, and hulling. Other
operations specific to individual nuts and seeds include sizing, grading, skinning, and oil or dry
roasting. The processing of harvested nuts and seeds can produce paniculate emissions primarily from
the unloading, precleaning, hulling or shelling, and screening operations. In almond processing, all
of the operations, except for unloading, are usually controlled to reduce the level of ambient
paniculate. The emissions from the unloading operation are usually uncontrolled.
In this document, the industry is divided into Section 9.10.2.1, "Almond Processing", and
Section 9.10.2.2, "Peanut Processing". Sections on other nuts and seeds may be published in later
editions if sufficient data on the processes are available.
1/95 Food And Agricultural Industry 9.10.2-1
-------
9.10.2.1 Almond Processing
9.10.2.1.1 General1'2
Almonds are edible tree nuts, grown principally in California. The nuts are harvested from
orchards and transported to almond processing facilities, where the almonds are hulled and shelled.
The function of an almond huller/sheller is to remove the hull and shell of the almond from the nut,
or meat. Orchard debris, soil, and pebbles represent 10 to 25 percent of the field weight of material
brought to the almond processing facility. Clean almond meats are obtained as about 20 percent of
the field weight. Processes for removing the debris and almond hulls and shells are potential sources
of air emissions.
9.10.2.1.2 Process Description1'7
After almonds are collected from the field, they undergo two processing phases, post-harvest
processing and finish processing. These phases are typically conducted at two different facilities.
There are two basic types of almond post-harvest processing facilities: those that produce hulled, in-
shell almonds as a final product (known as hullers), and those that produce hulled, shelled, almond
meats as a final product (known as huller/shellers). Almond precleaning, hulling, and separating
operations are common to both types of facilities. The huller/sheller includes additional steps to
remove the almond meats from their shells. A typical almond hulling operation is shown in
Figure 9.10.2.1-1. A typical almond huller/sheller is depicted in Figure 9.10.2.1-2. The hulled,
shelled almond meats are shipped to large production facilities where the almonds may undergo
further processing into various end products. Almond harvesting, along with precleaning, hulling,
shelling, separating, and final processing operations, is discussed in more detail below.
Almond harvesting and processing are a seasonal industry, typically beginning in August and
running from two to four months. .However, the beginning and duration of the season vary with the
weather and with the size of the crop. The almonds are harvested either manually, by knocking the
nuts from the tree limbs with a long pole, or mechanically, by shaking them from the tree. Typically
the almonds remain on the ground for 7 to 10 days to dry. The fallen almonds are then swept into
rows. Mechanical pickers gather the rows for transport to the almond huller or huller/sheller. Some
portion of the material in the gathered rows includes orchard debris, such as leaves, grass, twigs,
pebbles, and soil. The fraction of debris is a function of farming practices (tilled versus untilled),
field soil characteristics, and age of the orchard, and it can range from less than 5 to 60 percent of
the material collected. On average, field weight yields 13 percent debris, 50 percent hulls, 14 percent
shells, and 23 percent clean almond meats and pieces, but these ratios can vary substantially from
farm to farm.
The almonds are delivered to the processing facility and are dumped into a receiving pit. The
almonds are transported by screw conveyors and bucket elevators to a series of vibrating screens.
The screens selectively remove orchard debris, including leaves, soil, and pebbles. A destoner
removes stones, dirt clods, and other larger debris. A detwigger removes twigs and small sticks.
The air streams from the various screens, destoners, and detwiggers are ducted to cyclones or fabric
filters for paniculate matter removal. The recovered soil and fine debris, such as leaves and grass,
are disposed of by spreading on surrounding farmland. The recovered twigs may be chipped and
used as fuel for co-generation plants. The precleaned almonds are transferred from the precleaner
area by another series of conveyors and elevators to storage bins to await further processing. (In
1/95 Food And Agricultural Industry 9.10.2.1-1
-------
CYCLONE OR
BAGHOUSE
LEAVES, STICKS, STONES,
DIRT, AND ORCHARD
TRASH
UNLOADING ALMONDS
TO RECEIVING PIT
(SCC 3-02-017-11)
PRECLEANING
ORCHARD DEBRIS
FROM ALMONDS
(SCC 3-02-017-12)
DRYING
= PM EMISSIONS
TEMPORARY
STORAGE
IN-SHELL
NUTS
GRAVITY SEPARATOR/
CLASSIFIER SCREEN
DECK
(SCC 3-02-017-15)
AIR LEG
(SCC 3-02-017-16)
RECYCLE TO HULLERS
AND SCREENS
MEATS
HULLS
•
HULL REMOVAL AND
SEPARATION OF
IN-SHELL ALMONDS
(SCC 3-02-017-13)
HULLING
CYLINDER
GRAVITY SEPARATOR/
CLASSIFIER SCREEN
DECK
(SCC 3-02-017-15)
AIR LEG
(SCC 3-02-017-16)
SCREEN
FINE
TRASH
CYCLONE OR
BAGHOUSE
HULLS
•
RECYCLE TO HULLERS
AND SCREENS
COLLECTION
Figure 9.10.2.1-1. Representative almond hulling process flow diagram.
(Source Classification Codes in parentheses.)
9.10.2.1-2
EMISSION FACTORS
1/95
-------
CYCLONE OR
BAGHOUSE
LEAVES, STICKS, STONES,
DIRT, AND ORCHARD
TRASH
UNLOADING
ALMONDS TO
RECEIVING PIT
(SCC 3-02-017-11)
PRECLEANING
ORCHARD DEBRIS
FROM ALMONDS
(SCC 3-02-017-12)
= PM EMISSIONS
= POTENTIAL VOC EMISSION
DRYING
TEMPORARY
STORAGE
HULL
ASPIRATION
SHEAR
ROLLS
SCREENS
HULLING/SHELLING
(SCC 3-02-017-14)
SHEAR
ROLLS
SCREENS
v
SHELL
ASPIRATION
SHELL
ASPIRATION
HULL
ASPIRATION
AIR 1
i
SHI
4
.EGS
ELLS
»
t
GRAVITY SEPARATORS/
CLASSIFIER SCREEN
DECK (SCC 3-02-01 7-1 5)
i
REO
r
'CLE TO
MEATS ROASTER
(SCC 3-02-01 7-1 7)
SHEAR ROLLS AND
SCREENS
Figure 9.10.2.1-2. Representative almond huller/sheller process flow diagram.
(Source Classification Codes in parentheses.)
1/95
Food And Agricultural Industry
9.10.2.1-3
-------
some instances, the precleaned almonds may be conveyed to a dryer before storage. However, field
drying is used in most operations.)
Almonds are conveyed on belt and bucket conveyors to a series of hulling cylinders or shear
rolls, which crack the almond hulls. Hulling cylinders are typically used in almond huller facilities.
Series of shear rolls are generally used in huller/shellers. The hulling cylinders have no integral
provision for aspiration of shell pieces. Shear rolls, on the other hand, do have integral aspiration to
remove shell fragments from loose hulls and almond meats. The cracked almonds are then
discharged to a series of vibrating screens or a gravity table, which separates hulls and unhulled
almonds from the in-shell almonds, almond meats, and fine trash. The remaining unhulled almonds
pass through additional hulling cylinders or shear rolls and screen separators. The number of passes
and the combinations of equipment vary among facilities. The hulls are conveyed to storage and sold
as an ingredient in the manufacture of cattle feed. The fine trash is ducted to a cyclone or fabric
filter for collection and disposal.
In a hulling facility, the hulled, in-shell almonds are separated from any remaining hull pieces
in a series of air legs (counter-flow forced air gravity separators) and are then graded, collected, and
sold as finished product, along with an inevitable small percentage of almond meats. In
huller/shellers, the in-shell almonds continue through more shear rolls and screen separators.
As the in-shell almonds make additional passes through sets of shear rolls, the almond shells
are cracked or sheared away from the meat. More sets of vibrating screens separate the shells from
the meats and small shell pieces. The separated shells are aspirated and collected in a fabric filter or
cyclone, and then conveyed to storage for sale as fuel for co-generation plants. The almond meats
and small shell pieces are conveyed on vibrating conveyor belts and bucket elevators to air classifiers
or air legs that separate the small shell pieces from the meats. The number of these air separators
varies among facilities. The shell pieces removed by these air classifiers are also collected and stored
for sale as fuel for co-generation plants. The revenues generated from the sale of hulls and shells are
generally sufficient to offset the costs of operating the almond processing facility.
The almond meats are then conveyed to a series of gravity tables or separators (classifier
screen decks), which sort the meats by lights, middlings, goods, and heavies. Lights, middlings, and
heavies, which still contain hulls and shells, are returned to various points in the process. Goods are
conveyed to the finished meats box for storage. Any remaining shell pieces are aspirated and sent to
shell storage.
The almond meats are now ready either for sales as raw product or for further processing,
typically at a separate facility. The meats may be blanched, sliced, diced, roasted, salted, or smoked.
Small meat pieces may be ground into meal or pastes for bakery products. Almonds are roasted by
gradual heating in a rotating drum. They are heated slowly to prevent the skins and outer layers from
burning. Roasting time develops the flavor and affects the color of the meats. To obtain almonds
with a light brown color and a medium roast requires a 500-pound roaster fueled with natural gas
about 1.25 hours at 118°C (245°F).
9.10.2.1.3 Emissions And Controls1'3'5'9
Paniculate matter (PM) is the primary air pollutant emitted from almond post-harvest
processing operations. All operations in an almond processing facility involve dust generation from
the movement of trash, hulls, shells, and meats. The quantity of PM emissions varies depending on
the type of facility, harvest method, trash content, climate, production rate, and the type and number
of controls used by the facility. Fugitive PM emissions are attributable primarily to unloading
9.10.2.1-4 EMISSION FACTORS 1/95
-------
operations, but some fugitive emissions are generated from precleaning operations and subsequent
screening operations.
Because farm products collected during harvest typically contain some residual dirt, which
includes trace amounts of metals, it stands to reason that some amount of these metals will be emitted
from the various operations along with the dust. California Air Resources Board (CARB) data
indicate that metals emitted from almond processing include arsenic, beryllium, cadmium, copper,
lead, manganese, mercury, and nickel in quantities on the order of 5 x 10"11 to 5 x 10"4 kilograms
(kg) of metal per kg of PM emissions (5 x 10"11 to 5 x 10"4 pounds [Ib] of metal per Ib of PM
emissions). It has been suggested that sources of these metals other than the inherent trace metal
content of soil may include fertilizers, other agricultural sprays, and groundwater.
In the final processing operations, almond roasting is a potential source of volatile organic
compound (VOC) emissions. However, no chemical characterization data are available to hypothesize
what compounds might be emitted, and no emission source test data are available to quantify these
potential emissions.
Emission control systems at almond post-harvest processing facilities include both ventilation
systems to capture the dust generated during handling and processing of almonds, shells, and hulls,
and an air pollution control device to collect the captured PM. Cyclones formerly served as the
principal air pollution control devices for PM emissions from almond post harvest processing
operations. However, fabric filters, or a combination of fabric filters and cyclones, are becoming
common. Practices of combining and controlling specific exhaust streams from various operations
vary considerably among facilities. The exhaust stream from a single operation may be split and
ducted to two or more control devices. Conversely, exhaust streams from several operations may be
combined and ducted to a single control device. According to one source within the almond
processing industry, out of approximately 350 almond hullers and huller/shellers, no two are alike.
Emission factors for almond processing sources are presented in Table 9.10.2.1-1.
1/95 Food And Agricultural Industry 9.10.2.1-5
-------
Table 9.10.2.1-1 (Metric And English Units). EMISSION FACTORS FOR ALMOND
PROCESSING*
EMISSION FACTOR RATING: E
Source
Unloading0
(SCC 3-02-017-11)
Precleaning cycloned
(SCC 3-02-017-12)
Precleaning baghouse6
(SCC 3-02-017-12)
Hulling/separating cycloned
(SCC 3-02-017-13)
Hulling/separating baghousee
(SCC 3-02-017-13)
Hulling/shelling baghousef
(SCC 3-02-017-14)
Classifier screen deck
cycloned
(SCC 3-02-017-15)
Air legd
(SCC 3-02-017-16)
Roaster8
(SCC 3-02-017-17)
Filterable PM
kg/Mg
0.030
0.48
0.0084
0.57
0.0078
0.026
0.20
0.26
ND
Ib/ton
0.060
0.95
0.017
1.1
0.016
0.051
0.40
<
0.51
ND
Condensable Inorganic
PM
kg/Mg
ND
ND
ND
ND
ND
0.0068
ND
ND
ND
Ib/ton
ND
ND
ND
ND
ND
0.014
ND
ND
ND
PM-10b
kg/Mg
ND
0.41
0.0075
0.41
0.0065
ND
0.16
ND
ND
Ib/ton
ND
0.82
0.015
0.81
0.013
ND
0.31
ND
ND
a Process weights used to calculate emission factors include nuts and orchard debris as taken from the
field, unless noted. ND = no data. SCC = Source Classification Code.
b PM-10 factors are based on particle size fractions found in Reference 1 applied to the filterable PM
emission factor for that source. See Reference 3 for a detailed discussion of how these emission
factors were developed.
c References 1-3,10-11.
d Reference 1. Emission factor is for a single air leg/classifier screen deck cyclone. Facilities may
contain multiple cyclones.
e References 1,9.
f Reference 10.
g Factors are based on finished product throughputs.
9.10.2.1-6
EMISSION FACTORS
1/95
-------
References For Section 9.10.2.1
1. Report On Tests Of Emissions From Almond Hullers In The San Joaquin Valley, File
No. C-4-0249, California Air Resources Board, Division Of Implementation And
Enforcement, Sacramento, CA, 1974.
2. Proposal To Almond Hullers And Processors Association For Pooled Source Test, Eckley
Engineering, Fresno, CA, December 1990.
3. Emission Factor Documentation For AP-42 Section 9.10.2, Salted And Roasted Nuts And
Seeds, EPA Contract No. 68-D2-0159, Midwest Research Institute, Gary, NC, May 1994.
4. Jasper Guy Woodroof, Tree Nuts: Production, Processing Product, Avi Publishing, Inc.,
Westport, CT, 1967.
5. Written communication from Darin Lundquist, Central California Almond Growers
Association, Sanger, CA, to Dallas Safriet, U.S. Environmental Protection Agency, Research
Triangle Park, NC, July 9, 1993.
6. Written communication from Jim Ryals, Almond Hullers and Processors Association,
Bakersfield, CA, to Dallas Safriet, U. S. Environmental Protection Agency, Research
Triangle Park, NC, July 7, 1993.
7. Written communication from Wendy Eckley, Eckley Engineering, Fresno, CA, to Dallas
Safriet, U. S. Environmental Protection Agency, Research Triangle Park, NC, July 7, 1993.
8. Private communications between Wendy Eckley, Eckley Engineering, Fresno, CA, and Lance
Henning, Midwest Research Institute, Kansas City, MO, August-September 1992, March
1993.
9. Almond Huller Baghouse Emissions Tests, Superior Farms, Truesdail Laboratories, Los
Angeles, CA, November 5, 1980.
10. Emission Testing On Two Baghouses At Harris Woolf California Almonds, Steiner
Environmental, Inc., Bakersfield, CA, October 1991.
11. Emission Testing On One Baghouse At Harris Woolf California Almonds, Steiner
Environmental, Inc., Bakersfield, CA, October 1992.
1/95 Food And Agricultural Industry 9.10.2.1-7
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9.10.2.2 Peanut Processing
9.10.2.2.1 General
Peanuts (Arachis hypogaed), also known as groundnuts or goobers, are an annual leguminous
herb native to South America. The peanut peduncle, or peg (the stalk that holds the flower),
elongates after flower fertilization and bends down into the ground, where the peanut seed matures.
Peanuts have a growing period of approximately 5 months. Seeding typically occurs mid-April to
mid-May, and harvesting during August in the United States.
Light, sandy loam soils are preferred for peanut production. Moderate rainfall of between
51 and 102 centimeters (cm) (20 and 40 inches [in.]) annually is also necessary. The leading peanut
producing states are Georgia, Alabama, North Carolina, Texas, Virginia, Florida, and Oklahoma.
9.10.2.2.2 Process Description
The initial step in processing is harvesting, which typically begins with the mowing of mature
peanut plants. Then die peanut plants are inverted by specialized machines, peanut inverters, that dig,
shake, and place the peanut plants, with the peanut pods on top, into windrows for field curing.
After open-air drying, mature peanuts are picked up from the windrow with combines that separate
the peanut pods from the plant using various thrashing operations. The peanut plants are deposited
back onto the fields and the pods are accumulated in hoppers. Some combines dig and separate the
vines and stems from the peanut pods in 1 step, and peanuts harvested by this method are cured in
storage. Some small producers still use traditional harvesting methods, plowing the plants from the
ground and manually stacking them for field curing.
Harvesting is normally followed by mechanical drying. Moisture in peanuts is usually kept
below 12 percent, to prevent aflatoxin molds from growing. This low moisture content is difficult to
achieve under field conditions without overdrying vines and stems, which reduces combine efficiency
(less foreign material is separated from the pods). On-farm dryers usually consist of either storage
trailers with air channels along the floor or storage bins with air vents. Fans blow heated air
(approximately 35 °C [95 °F]) through the air channels and up through the peanuts. Peanuts are dried
to moistures of roughly 7 to 10 percent.
Local peanut mills take peanuts from the farm to be further cured (if necessary), cleaned,
stored, and processed for various uses (oil production, roasting, peanut butter production, etc.).
Major process steps include processing peanuts for in-shell consumption and shelling peanuts for other
uses.
9.10.2.2.2.1 In-shell Processing -
Some peanuts are processed for in-shell roasting. Figure 9.10.2.2-1 presents a typical flow
diagram for in-shell peanut processing. Processing begins with separating foreign material (primarily
soil, vines, stems, and leaves) from the peanut pods using a series of screens and blowers. The pods
are then washed in wet, coarse sand that removes stains and discoloration. The sand is then screened
from the peanuts for reuse. The nuts are then dried and powdered with talc or kaolin to whiten the
shells. Excess talc/kaolin is shaken from the peanut shells.
1/95 Food And Agricultural Industry 9.10.2.2-1
-------
LEAVES, STEMS, VINES,
STONES, AND OTHER TRASH
UNLOADING
DRYING
POWDERING
DRYING
SCREENING
PRECLEANING
SAND
IN-SHELL PEANUT
PACKAGING
TALC OR
KAOLIN
= PM EMISSIONS
Figure 9.10.2.2-1. Typical in-shell peanut processing flow diagram.
9.10.2.2-2
EMISSION FACTORS
1/95
-------
9.10.2.2.2.2 Shelling -
A typical shelled peanut processing flow diagram is shown in Figure 9.10.2.2-2. Shelling
begins with separating the foreign material with a series of screens, blowers, and magnets. The
cleaned peanuts are then sized with screens (size graders). Sizing is required so that peanut pods can
be crushed without also crushing the peanut kernels.
Next, shells of the sized peanuts are crushed, typically by passing the peanuts between rollers
that have been adjusted for peanut size. The gap between rollers must be narrow enough to crack the
peanut hulls, but wide enough to prevent damage to the kernels. A horizontal drum, with a
perforated and ridged bottom and a rotating beater, is also used to hull peanuts. The rotating beater
crushes the peanuts against the bottom ridges, pushing both the shells and peanuts through the
perforations. The beater can be adjusted for different sizes of peanuts, to avoid damaging the peanut
kernels. Shells are aspirated from the peanut kernels as they fall from the drum. The crushed shells
and peanut kernels are then separated with oscillating shaker screens and air separators. The
separation process also removes undersized kernels and split kernels.
Following crushing and hull/kernel separation, peanut kernels are sized and graded. Sizing
and grading can be done by hand, but most mills use screens to size kernels and electric eye sorters
for grading. Electric eye sorters can detect discoloration and can separate peanuts by color grades.
The sized and graded peanuts are bagged in 45.4-kg (100-lb) bags for shipment to end users, such as
peanut butter plants and nut roasters. Some peanuts are shipped in bulk in rail hopper cars.
9.10.2.2.2.3 Roasting-
Roasting imparts the typical flavor many people associate with peanuts. During roasting,
amino acids and carbohydrates react to produce tetrahydrofuran derivatives. Roasting also dries the
peanuts further and causes them to turn brown as peanut oil stains the peanut cell walls. Following
roasting, peanuts are prepared for packaging or for further processing into candies or peanut butter.
Typical peanut roasting processes are shown in Figure 9.10-2.2-3. There are 2 primary methods for
roasting peanuts, dry roasting and oil roasting.
Dry Roasting -
Dry roasting is either a batch or continuous process. Batch roasters offer the advantage of
adjusting for different moisture contents of peanut lots from storage. Batch roasters are typically
natural gas-fired revolving ovens (drum-shaped). The rotation of the oven continuously stirs the
peanuts to produce an even roast. Oven temperatures are approximately 430°C (800°F), and peanut
temperature is raised to approximately 160°C (320°F) for 40 to 60 min. Actual roasting temperatures
and times vary with the condition of the peanut batch and the desired end characteristics.
Continuous dry roasters vary considerably in type. Continuous roasting reduces labor,
ensures a steady flow of peanuts for other processes (packaging, candy production, peanut butter
production, etc.), and decreases spillage. Continuous roasters may move peanuts through an oven on
a conveyor or by gravity feed. In one type of roaster, peanuts are fed by a conveyor into a stream of
countercurrent hot air that roasts the peanuts. In this system, the peanuts are agitated to ensure that
air passes around the individual kernels to promote an even roast.
Dry roasted peanuts are cooled and blanched. Cooling occurs in cooling boxes or on
conveyors where large quantities of air are blown over the peanuts immediately following roasting.
Cooling is necessary to stop the roasting process and maintain a uniform quality. Blanching removes
the skin of the peanut as well as dust, molds, and other foreign material. There are several blanching
methods including dry, water, spin, and air impact.
1/95 Food And Agricultural Industry 9.10.2.2-3
-------
UNLOADING
SHELL ASPIRATION
I
SCREENING
LEAVES, STEMS, VINES,
STONES, AND OTHER TRASH
DRYING
ROLL
CRUSHING
\
SHELL ASPIRATION
AIR
SEPARATING
KERNEL SIZING
AND GRADING
SHELLED PEANUT
- BAGGING OR
BULK SHIPPING
SHELL ASPIRATION
= PM EMISSIONS
Figure 9.10.2.2-2. Typical shelled peanut processing flow diagram.
9.10.2.2-4
EMISSION FACTORS
1/95
-------
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1/95
Food And Agricultural Industry
9.10.2.2-5
-------
Dry blanching is used primarily in peanut butter production, because it removes the kernel
hearts which affect peanut butter flavor. Dry blanching heats the peanuts to approximately 138 °C
(280°F) for 25 minutes to crack and loosen the skins. The heated peanuts are then cooled and passed
through either brushes or ribbed rubber belting to rub off the skins. Screening is used to separate the
hearts from the cotyledons (peanut halves).
Water blanching passes the peanuts on conveyors through stationary blades that slit the peanut
skins. The skins are then loosened with hot water sprayers and removed by passing the peanuts under
oscillating canvas-covered pads on knobbed conveyor belts. Water blanching requires drying the
peanuts back to a moisture content of 6 to 12 percent.
Spin blanching uses steam to loosen the skins of the peanuts. Steaming is followed by
spinning the peanuts on revolving spindles as the peanuts move, single file, down a grooved
conveyor. The spinning unwraps the peanut skins.
Air impact blanching uses a horizontal drum (cylinder) in which the peanuts are placed and
rotated. The inner surface of the drum has an abrasive surface that aids in the removal of the skins as
the drum rotates. Inside the drum are air jets that blow the peanuts counter to the rotation of the
drum creating air impact which loosens the skin. The combination of air impacts and the abrasive
surface of the drum results in skin removal. Either batch or continuous air impact blanching can be
conducted.
Oil Roasting -
Oil roasting is also done on a batch or continuous basis. Before roasting, the peanuts are
blanched to remove the skins. Continuous roasters move the peanuts on a conveyor through a long
tank of heated oil. In both batch and continuous roasters, oil is heated to temperatures of 138 to
143°C (280 to 290°F), and roasting times vary from 3 to 10 minutes depending on desired
characteristics and peanut quality. Oil roaster tanks have heating elements on the sides to prevent
charring the peanuts on the bottom. Oil is constantly monitored for quality, and frequent filtration,
neutralization, and replacement are necessary to maintain quality. Coconut oil is preferred, but oils
such as peanut and cottonseed are frequently used.
Cooling also follows oil roasting, so that a uniform roast can be achieved. Cooling is
achieved by blowing large quantities of-air over the peanuts either on conveyors or in cooling boxes.
9.10.2.2.3 Emissions And Controls
No information is currently available on emissions or emission control devices for the peanut
processing industry. However, the similarities of some of the processes to those in the almond
processing industry make it is reasonable to assume that emissions would be comparable. No data are
available, however, to make any comparisons about relative quantities of these emissions.
Reference For Section 9.10.2.2
1. Jasper Guy Woodroof, Peanuts: Production, Processing, Products, 3rd Edition, Avi
Publishing Company, Westport, CT, 1983.
9.10.2.2-6 EMISSION FACTORS 1/95
-------
9.11 Fats And Oils
[Work In Progress]
1/95
Food And Agricultural Industries 9.11-1
-------
9.11.1 Vegetable Oil Processing
9.11.1.1 General1'5
The industry group producing fats and oils includes cottonseed oil mills, soybean oil mills,
vegetable oil mills (other than corn, cottonseed, and soybean), and other mills. Wet corn mills are
the primary producers of corn oil. Approximately 137 vegetable oil plants operate in the United
States. Soybean processing, which dominates the industry, produces approximately 80 percent of the
volume of vegetable oil and is concentrated in the states of Iowa, Illinois, Missouri, Kansas, Indiana,
and Minnesota, but also found across the nation. Likewise, wet corn mills are concentrated in Corn
Belt states. Cottonseed oil mills are found in southern states and California.
,6-9
9.11.1.2 Process Description
The following process description discusses only soybean oil manufacture, because emission
factors are available only for that activity. Corn, cottonseed, and peanut oil processing are similar to
soybean processing, except for differences in the soybean preparation for oil extraction. The process
for soybeans typically consists of five steps: oilseed handling/elevator operations, preparation of
soybeans for solvent extraction, solvent extraction and oil desolventizing, flake desolventizing, and oil
refining.
Oilseed Handling/Elevator Operations -
Figure 9.11.1-1 is a schematic diagram of a typical soybean handling/elevator operation that
precedes the preparation of soybeans for the solvent extraction process.
Soybeans received at the facility by truck or rail are sampled and analyzed for moisture
content, foreign matter, and damaged seeds. Then the beans are weighed and conveyed to large
concrete silos or metal tanks for storage prior to processing. When the facility is ready to process the
soybeans, the beans are removed from the silo or tank and cleaned of foreign materials and loose
hulls. Screens typically are used to remove foreign materials such as sticks, stems, pods, tramp
metal, sand, and dirt. An aspiration system is used to remove loose hulls from the soybeans; these
hulls may be combined later with hulls from the dehulling aspiration step. The beans are passed
through dryers to reduce their moisture content to approximately 10 to 11 percent by weight and then
are conveyed to process bins for temporary storage and tempering for 1 to 5 days in order to facilitate
dehulling.
Preparation Of Soybeans For Solvent Extraction -
Figure 9.11.1-2 is a schematic diagram of the process used to prepare soybeans for the
solvent extraction process. The process, which is fairly well standardized, consists of four principal
operations: cracking, dehulling/hull removal, conditioning, and flaking.
Soybeans are conveyed from the process bins to the mill by means of belts or mass flow
conveyors and bucket elevators. In the mill, the beans may be aspirated again, weighed, cleaned of
tramp metal by magnets, and fed into corrugated cracking rolls. The cracking rolls "crack" each
bean into four to six particles, which are passed through aspirators to remove the hulls (processed
separately after the removal of residual bean chips). These hulls may be combined with the hulls
from the grain cleaning step.
11/95 Food And Agricultural Industry 9.11.1-1
-------
Sampling
Raw Soybean
Receiving
(3-02-007-81)
Handling/Storage
(3-02-007-82)
Grain Cleaning
(3-02-007-83)
Grain Drying
(3-02-007-84)
Process Bins
T
Soybeans To Preparation
(see Figure 9.11.1-2)
Paniculate Emissions
Paniculate Emissions
Trash
Hulls (may be combined with hulls
from dehulling aspiration)
(see Figure 9.11.1-2)
-**• Paniculate Emissions
Figure 9.11.1-1. Flow diagram of typical soybean handling/elevator operations.
(Source Classification Codes in parentheses.)
9.11.1-2
EMISSION FACTORS
11/95
-------
Soybeans from
Handling/Elevator
Operations
(see Figure 9.11.1-1)
OPTIONAL PROCESS
Aspiration
Paniculate^
Emissions"
Paniculate^
Emissions"
Paniculate^
Emissions"
Cracking
(3-02-007-85)
Paniculate
Emissions
Dehulling Aspiration
(3-02-007-85)
Hulls with Beans
Bean Return
Cracked Bean
Conditioning
(3-02-007-87)
Dehulling Aspiration
(3-02-007-85)
Flaking
(3-02-007-88)
Paniculate
Emissions
Hulls
Hulls from Grain
Cleaning
(see Figure 9.11.1-1)
Hulls to Sizing, Grinding,
and Loadout
(see Figure 9.11.1-4)
Flakes to Solvent Extraction
(see Figure 9.11.1-3)
Figure 9.11.1-2. Flow diagram of the typical process for preparing soybeans for solvent extraction.
(Source Classification Codes in parentheses.)
11/95
Food And Agricultural Industry
9.11.1-3
-------
Next, the cracked beans and bean chips are conveyed to the conditioning area, where they are
put either into a rotary steam tubed device or into a stacked cooker and are heated to "condition"
them (i. e., make them pliable and keep them hydrated). Conditioning is necessary to permit the
flaking of the chips and to prevent their being broken into smaller particles. Finally, the heated,
cracked beans are conveyed and fed to smooth, cylindrical rolls that press the particles into smooth
"flakes", which vary in thickness from approximately 0.25 to 0.51 millimeters (0.010 to
0.020 inches). Flaking allows the soybean oil cells to be exposed and the oil to be more easily
extracted.
Solvent Extraction and Oil Desolventizing -
The extraction process consists of "washing" the oil from the soybean flakes with hexane
solvent in a countercurrent extractor. Then the solvent is evaporated (i. e., desolventized) from both
the solvent/oil mixture (micella) and the solvent-laden, defatted flakes (see Figure 9.11.1-3). The oil
is desolventized by exposing the solvent/oil mixture to steam (contact and noncontact). Then the
solvent is condensed, separated from the steam condensate, and reused. Residual hexane not
condensed is removed with mineral oil scrubbers. The desolventized oil, called "crude" soybean oil,
is stored for further processing or loadout.
Desolventizing Flakes -
The flakes leaving the extractor contain up to 35 to 40 percent solvent and must be
desolventized before use. Flakes are desolventized in one of two ways: either "conventional"
desolventizing or specialty or "flash" desolventizing. The method used depends upon the end use of
the flakes. Flakes that are flash desolventized are typically used for human foods, while
conventionally desolventized flakes are used primarily in animal feeds.
Conventional desolventizing takes place in a desolventizer-toaster (DT), where both contact
and noncontact steam are used to evaporate the hexane. In addition, the contact steam "toasts" the
flakes, making them more usable for animal feeds. The desolventized and toasted flakes then pass to
a dryer, where excess moisture is removed by heat, and then to a cooler, where ambient air is used to
reduce the temperature of the dried flakes. The desolventized, defatted flakes are then ground for use
as soybean meal (see Figure 9.11.1-4).
Flash desolventizing is a special process that accounts for less than 5 percent by volume of the
annual nationwide soybean crush. The production offtakes for human consumption generally follows
the flow diagram in Figure 9.11.1-3 for the "conventional" process, except for the desolventizing
step. In this step, the flakes from the oil extraction step are "flash" desolventized in a vacuum with
noncontact steam or superheated hexane. This step is followed by a final solvent stripping step using
steam. Both the hexane vapor from the flash/vacuum desolventizer and the hexane and steam vapors
from the stripper are directed to a condenser. From the condenser, hexane vapors pass to the mineral
oil scrubber and the hexane-water condensate goes to the separator, as shown in Figure 9.11.1-3.
The flakes produced by the flash process are termed "white flakes". A process flow diagram for the
flash desolventizing portion of the soybean process is shown in Figure 9.11.1-5. From the stripper,
the white flakes pass through a cooker (an optional step) and a cooler prior to further processing steps
similar to the "conventional" process. A plant that uses specialty or "flash" desolventizing requires
different equipment and is far less efficient in energy consumption and solvent recovery than a plant
that uses conventional desolventizing. Given these facts, solvent emissions are considerably higher
for a specialty desolventizing process than for a similar-sized conventional desolventizing process.
9.11.1-4 EMISSION FACTORS 11195
-------
Flakes from
Preparation
(seeRgure9.11.1-2)
Hexane and Steam Vapors
Water
Hexane
and
Water
Hexane and Steam Vapors.
Hexane Vapor to
Mineral Oil Scrubber
Hexane-Water
Condensate
Mineral Oil
Scrubber System
Hexane-Steam
Condensing
Hexane-Steam
Condensing
Main Vent
(3-02-019-16)
Hexane and
Steam Vapors
Figure 9.11.1-5)
Extracted
Rakes and
Hexane
Oil/Hexane
Distillation
Hexane Emissions
Hexane and
Steam Vapors
Crude OH
Storage
Desolventlzed and
Hexane and
Pardculate
Emissions
Further Processing
or Loadout
Hexane and
Paniculate
Emissions
Cooled Meal
Cooled Dried Meal to
Sizing. Grinding,
and Loadout
(see Figure 9.11.1 -4)
L
Soybean Extraction Facility—Total Hexane Losses
(3-02-019-97)
(3-02-019-98)
Figure 9.11.1-3. Flow diagram of the "conventional" solvent extraction process.
(Source Classification Codes in parentheses.)
11/95
Food And Agricultural Industry
9.11.1-5
-------
Paniculate,
Emissions
Cooled Dried Meal from
Solvent Extraction
(Figure 9.11.1-3)
Meal Grinding
and Sizing
(3-02-007-93)
Meal Storage
(High Protein)
48% Protein*
Hulls from
Dehulling Aspiration
(Figure 9.11.1-2)
Meal-Millfeed
Blending
44% Protein Meal
Sampling
Loadout
(Rail, Truck, Barge)
(3-02-007-91)
Hull Grinding
and Sizing
(3-02-007-86)
Paniculate
Emissions
OPTIONAL PROCESS
Toasted Hull
(Millfeed) Storage
10% Protein*
Meal Storage
(Low Protein)
I J
I *
Hull Toasting
Typical or nominal values;
actual values may vary.
. Paniculate
Emissions
Figure 9.11.1-4. Flow diagram for "conventional" process of dry material sizing, grinding,
and loadout.
(Source Classification Codes in parentheses.)
9.11.1-6
EMISSION FACTORS
11/95
-------
Solvent Laden Flakes
From Oil Extraction
(see (Figure 9.11.1-3)
Super-W
Hexane
Hexane Vapor
Stripping Stei
P articulate
Emissions
Defatted, Desolventlzed
Flakes to Further
Processing
Figure 9.11.1-5. Flow diagram of the flash desolventi/ing process.
(Source Classification Code in parentheses.)
Vegetable Oil Refining -
Crude oil is typically shipped for refining to establishments engaged in the production of
edible vegetable oils, shortening, and margarine. Crude vegetable oils contain small amounts of
naturally occurring materials such as proteinaceous material, free fatty acids, and phosphatides.
Phosphatides are removed for lecithin recovery or to prepare the crude oil for export. The most
common method of refining oil is by reacting it with an alkali solution which neutralizes the free fatty
acids and reacts with the phosphatides. These reacted products and the proteinaceous materials are
then removed by centrifuge. Following alkali refining, the oil is washed with water to remove
residual soap, caused by saponification of small amounts of the triglycerides (oil). Color-producing
substances within an oil (i. e., carotenoids, chlorophyll) are removed by a bleaching process, which
employs the use of adsorbents such as acid-activated clays. Volatile components are removed by
deodorization, which uses steam injection under a high vacuum and temperature. The refined oil is
then filtered and stored until used or transported.
11/95
Food And Agricultural Industry
9.11.1-7
-------
9.11.1.3 Emissions And Controls6'10-20
Emissions -
Paniculate matter and volatile organic compounds are the principal emissions from vegetable
oil processing. Particulate matter (PM) results from the transfer, handling, and processing of raw
seed. VOC emissions are the oil extraction solvent, hexane, which is classified as a hazardous air
pollutant. Particulate emissions from grain handling are discussed in the Interim AP-42
Section 9.9.1, "Grain Elevators And Processes".
Solvent emissions arise from several sources within vegetable oil processing plants. There are
potential solvent emissions from the transfer and storage of hexane on site as well as potential leaks
from piping and vents. Small quantities of solvent (up to 0.2 percent by volume of oil) are present in
the crude vegetable oil after the solvent is recovered by film evaporators and the distillation stripper.
This hexane may volatilize during the oil-refining process; however, no emission data are available.
Trace quantities of solvent are present and available for volatilization in waste water collected from
the condensation of steam used in the distillation stripper and desolventizer-toaster. Emission data
from waste water also are not available.
Vents are another source of emissions. Solvent is discharged from three vents: the main vent
from the solvent recovery section, the vent from the meal dryer, and the vent from the meal cooler.
The main vent receives gases from the oil extractor, the film evaporator and distillation stripper, and
the desolventizer-toaster. Vents for the meal dryer and meal cooler typically vent to atmosphere.
Hexane Emissions -
The recommended method for estimating annual hexane emissions from soybean solvent
extraction facilities is to obtain the annual hexane usage from the specific plant's records, and to
assume that all hexane make-up is due to losses to the air (SCC 3-02-019-97). (Some hexane leaves
the facilities as a small fraction of the oil or meal products, but this amount has not been quantified.)
If the hexane usage is determined from purchase records and the purchased amount accounts for any
change in quantities stored on-site, then storage tank losses would already be accounted for in the loss
estimate. If the usage is determined from the amount metered out of the storage tanks, then the
storage tank losses should be calculated separately, and in addition to, the usage losses, using the
equations in AP-42 Chapter 7 or in the TANKS software. Careful application of such a material
balance approach should produce emission estimates comparable in quality to those derived from a B-
rated emission factor.
The mean total hexane loss reported by the plants in References 11 through 19 was 3.3 L/Mg
(0.89 gal/ton [4.9 lb/ton]) of raw soybeans processed (SCC 3-02-019-98). This represents an overall
total loss factor for soybean oil processing, encompassing all sources of vented and fugitive emissions
(and storage tanks), as well as any hexane leaving the facility as part of the oil or meal products. For
a new facility or if plant-specific usage data are unavailable, this factor, rated D, can be used as a
default value until the relevant data for the facility become available. The default value should be
used only until the facility can compile the data needed to develop a plant-specific hexane loss for the
period of interest.
Particulate Emissions -
Table 9.11.1-1 presents emission factors for total PM emissions resulting from handling and
processing soybeans in vegetable oil manufacturing. Emission factors are provided for PM-generating
processes for the meal production process, including meal drying and cooling.
9.11.1-8 EMISSION FACTORS 11/95
-------
Table 9.11.1-1. TOTAL PARTICULATE EMISSION FACTORS FOR SOYBEAN MILLING-
EMISSION FACTOR RATING: E
Process
Receiving0 (SCC 3-02-007-81)
Handling (SCC 3-02-007-82)
Cleaning (SCC 3-02-007-83)
Drying (SCC 3-02-007-84)
Cracking/dehulling (SCC 3-02-007-85)
Hull grinding (SCC 3-02-007-86)
Bean conditioning (SCC 3-02-007-87)
Flaking rolls (SCC 3-02-007-88)
White flake cooler (SCC 3-02-007-92)
Meal cooler (SCC 3-02-007-90)
Meal dryer (SCC 3-02-007-89)
Meal grinder/sizing (SCC 3-02-007-93)
Meal loadoutd (SCC 3-02-007-91)
Control Device
None
ND
ND
ND
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
None
Emission Factor
(lb/ton)b
0.15
ND
ND
ND
0.36
0.20
0.010
0.037
0.95
0.19
0.18
0.34
0.27
Emission factors are based on pounds per ton of soybeans processed by the unit. Factors
represent controlled emissions, except as noted. Divide the Ib/ton factor by two to obtain
kg/Mg. SCC = Source Classification Code, ND = No Data.
Reference 21. These data were obtained from unpublished emission test data and from
industry questionnaires. Because these are secondary data, the test data and the questionnaire
results were weighed equally and the emission factors were calculated as arithmetic means of
the data. The emission factor rating is a reflection of the source of the data.
See Interim AP-42 Section 9.9.1, "Grain Elevators And Processes".
Reference 22.
Controls -
Hexane is recovered and reused in the oil-extraction process because of its cost. The steam
and hexane exhausts from the solvent extractor, desolventizer-toaster, and oil/hexane stripping are
passed through condensers to recover hexane. Residual hexane from the condensers is captured by
mineral oil scrubbers. The most efficient recovery or control device is a mineral oil scrubber (MOS),
which is approximately 95 percent efficient. The meal dryer and cooler vents are typically exhausted
to the atmosphere with only cyclone control to reduce particulate matter. Process controls to reduce
breakdowns and leaks can be used effectively to reduce emissions. Quantities of hexane may be lost
through storage tanks, leaks, shutdowns, or breakdowns. These losses are included in the material
balance.
11/95
Food And Agricultural Industry
9.11.1-9
-------
References for Section 9.11.1
1. P. T. Bartlett, et al., National Vegetable Oil Processing Plant Inventory, TRC Environmental
Consultants Inc., Wethersfield, CT, April 1980.
2. J. M. Farren, et al., U. S. Industrial Outlook '92, U. S. Department Of Commerce,
Washington, DC, 1992.
3. 1987 Census Of Manufactures: Fats And Oils, U.S. Department Of Commerce, Bureau Of
Census, Washington, DC, 1988.
4. Corn Annual 1992, Corn Refiners Association Inc., Washington, DC, 1992.
5. 95-96 Soya Bluebook Plus - Annual Directory Of The World Oilseed Industry, Soyatech, Inc.,
Bar Harbor, ME; data supplied by the National Oilseed Processors Association,
September 1995.
6. Control Of Volatile Organic Emissions From Manufacture Of Vegetable Oils,
EPA-450/2-78-035, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 1978.
7. Test Method For Evaluation QfHexane Emissions From Vegetable Oil Manufacturing, PEDCo
Environmental Inc., Cincinnati, OH, April 1979.
8. Written communication from D. C. Ailor, Director Of Regulatory Affairs, National Oilseed
Processors Association, Washington, DC, to D. Reisdorph, Midwest Research Institute,
Kansas City, MO, September 20, 1992.
9. Emission Factor Documentation For AP-42, Section 9.11.1, Vegetable Oil Processing,
Midwest Research Institute, Kansas City, MO, November 1995.
10. R. L. Chessin, "Investigating Sources Of Hexane Emissions", Oil Mill Gazetteer, 86(2):35-
36, 38-39, August 1981.
11. Vegetable Oil Production (Meal Processing) Emission Test Report, Cargill Incorporated (East
Plant), Cedar Rapids, Iowa, PEDCo Environmental Inc., Cincinnati, OH, June 1979.
12. Vegetable Oil Production (Meal Processing) Emission Test Report, Cargill Incorporated (West
Plant), Cedar Rapids, Iowa, PEDCo Environmental Inc., Cincinnati, OH, June 1979.
13. Vegetable Oil Production (Meal Processing) Emission Test Report, AGR1 Industries, Mason
City, Iowa, PEDCo Environmental Inc., Cincinnati, OH, June 1979.
14. Vegetable Oil Production (Meal Processing) Emission Test Report, Cargill Incorporated,
Fayetteville, North Carolina, PEDCo Environmental Inc., Cincinnati, OH, July 1979.
15. Vegetable Oil Manufacturing Emission Test Report, Central Soya Inc., Delphos, Ohio, EMB
Report 78-VEG-4, Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC, July 1979.
9.11.1-10 EMISSION FACTORS 11/95
-------
16. Vegetable Oil Production (Meal Processing) Emission Test Report, MFA Soybeans, Mexico,
Missouri, PEDCo Environmental Inc., Cincinnati, OH, July 1979.
17. Vegetable Oil Production (Meal Processing) Emission Test Report, Car gill Incorporated,
Sidney, Ohio, PEDCo Environmental Inc., Cincinnati, OH, July 1979.
18. Vegetable Oil Production (Meal Processing) Emission Test Report, Ralston Purina Company,
Memphis, Tennessee, PEDCo Environmental Inc., Cincinnati, OH, August 1979.
19. Vegetable Oil Production (Meal Processing) Emission Test Report, Ralston Purina Company,
Bloomington, Illinois, PEDCo Environmental Inc., Cincinnati, OH, August 1979.
20. "Liquid Storage Tanks", in Compilation Of Air Pollutant Emission Factors, Volume I:
Stationary Point And Area Sources, AP-42, U.S. Environmental Protection Agency, Research
Triangle Park, NC, January 1995.
21. Emissions Control In The Grain And Feed Industry, Volume I - Engineering And Cost Study,
EPA-450/3-73-003a, U.S. Environmental Protection Agency, Research Triangle Park, NC,
December 1973.
22. "Grain Elevators And Processing Plants", in Supplement B To Compilation Of Air Pollutant
Emission Factors, Volume I: Stationary Point And Area Sources, AP-42, U.S.
Environmental Protection Agency, Research Triangle Park, NC, September 1988.
11 /95 Food And Agricultural Industry 9.11.1-11
-------
9.12 Beverages
9.12.1 Malt Beverages
9.12.2 Wines And Brandy
9.12.3 Distilled And Blended Liquors
1/95 Food And Agricultural Industries 9.12-1
-------
9.12.1 Malt Beverages
9.12.1.1 Process Description1"4
The production of malt beverages, or beer, comprises four main stages: brewhouse
operations, fermentation, aging or secondary fermentation, and packaging. Figures 9.12.1-1,
9.12.1-2, 9.12.1-3, and 9.12.1-4 show the various stages of a typical brewing process, including
potential emission points.
Breweries typically purchase malted grain (malt) from malting operations. In the malting
process, grain is first soaked in water-filled steeping tanks for softening. After softening, the grain is
transferred to germination tanks, in which the grain germinates, typically over a 1-week period.
From the germination tanks, the grain enters a kiln, which halts germination by drying the grain. To
begin the brewing process, malt (usually barley malt) is transported by truck or rail to a brewery and
is conveyed to storage silos. The malt is then ground into malt flour by malt mills and transferred to
milled malt hoppers. Many small breweries purchase malt flour (malted and milled grain) from
facilities with malt mills. Malt provides the starch-splitting and protein-splitting enzymes that are
necessary to convert grain starches into fermentable sugars.
From the milled malt hoppers, the malt, along with hot water, is fed to the mash tun and
heated to convert grain starches to fermentable sugars. Some large facilities use high-temperature
mashing, which reduces the time required to convert the starches to sugars, but lowers the quantity of
fermentable sugars produced. Most breweries use one of the three principal mashing processes; these
are: double mashing, decoction, and infusion. Double mashing uses grains other than barley
(typically corn and rice) as starch adjuncts. Before being added to the mash tun, the adjunct grains
are broken down through cooking in a cereal cooker for about 1 hour at temperatures ranging from
40° to 100°C (104° to 212°F). Some plants do not use cereal cookers, but use additives such as
corn syrup that function as adjunct grains. The malt and adjuncts are then mixed and heated in the
mash tun. Decoction is a method of boiling portions of the mixture (mash) and adding the boiling
portions to the mash tun to raise the overall temperature to about 75°C (167°F). The infusion
process mixes the malt with hot water to maintain a uniform temperature (65° to 75°C [149° to
167°F]) until starch conversion is complete. Mixing, heating times, and temperatures vary among
breweries. The finished product of mashing is a grain slurry, called mash.
From the mash tun, the mash is pumped to a straining tank called a lauter tun, which
separates insoluble grain residues from the mash. The mash enters the lauter tun through a false
bottom where the insoluble grain residues are allowed to settle. The grain sediment acts as a filter for
the mash as it enters the tank. Various other filter agents, such as polypropylene fibers, are also
used. Some large breweries use strainmasters, which are a variation of lauter tuns. The spent grain
(brewers grain) from the lauter tun or strainmaster is conveyed to holding tanks, dried (by some
breweries), and sold as animal feed. Brewers grain dryers are typically fired with natural gas or fuel
oil. The product of the lauter tun is called wort.
The strained wort from the lauter tun is transferred to the brew kettle and is boiled, typically
for about 90 to 120 minutes. Boiling stops the starch-to-sugar conversion, sterilizes the wort,
precipitates hydrolyzed proteins, concentrates the wort by evaporating excess water, and facilitates
chemical changes that affect beer flavor. Hops are added to the wort during the boiling process.
Hops are high in iso-a acids, which impart the characteristic bitter flavor to beer. Some breweries
10/96 Food And Agricultural Industry 9.12.1-1
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add only hop extracts (that contain the desired iso-ce acids), and some breweries add hop extracts
during or after the fermentation process. After brewing, the hops are strained from the hot wort, and
the hot wort is pumped to a large settling tank, where it is held to allow the remaining insoluble
material (trub) to settle. The trub is transferred to the spent grain holding tanks. After settling, the
hot wort is pumped to a cooling system (typically a closed system), which cools the liquid to
temperatures ranging from about 7° to 12°C (44° to 54°F). Following cooling, yeast is added to the
cooled wort as it is pumped to the fermenters.
Fermentation takes place in large tanks (fermenters-typically with capacities _>.1,000 barrels
for medium to large breweries) that can be either open or closed to the atmosphere. Most closed-tank
fermenters include CO2 collection systems, which recover CO2 for internal use and remove organic
impurities from the CO2; water scrubbers and activated carbon adsorption systems are used to recover
impurities. These closed tank fermenters typically vent emissions to the atmosphere (for a specified
period of time) until the CO2 is pure enough to collect. The scrubber water is commonly discharged
as process wastewater, and the activated carbon is typically recharged (regenerated) on-site (the
impurities are typically vented to the atmosphere).
Fermentation is a biological process in which yeast converts sugars into ethyl alcohol
(ethanol), carbon dioxide (CO2), and water. Yeasts can ferment at either the bottom or the top of the
fermenter. Saccharomyces carlsbergensis are common bottom-fermenting yeasts used to produce
lager beers. Bottom-fermenting yeasts initially rise to the top of the fermenter, but then flocculate to
the bottom during rapid fermentation. When fermentation moderates, the beer is run off the top of
the fermenter, leaving the bottom-fermenting yeasts at the bottom of the tank. Saccharomyces
cerevisiae are top-fermenting yeasts commonly used to produce ales, porters, and stout beers. Top-
fermenting yeasts rise to the top of the fermenter during rapid fermentation and are skimmed or
centrifuged off the top when fermentation moderates. The type of yeast used and the length of the
fermentation process vary among breweries and types of beer. Most pilsner beers ferment at
temperatures varying from 6° to 20°C (43° to 68°F).
After primary fermentation, waste yeast is typically removed from the liquid (by centrifuges
or other means), and the liquid proceeds to a secondary fermentation or aging process. The liquid is
pumped to aging tanks, a small quantity of freshly fermenting wort is added (at some breweries), and
the mixture is stored at low temperatures (below about 5°C [41 °F]).
Several methods are used for the disposal of yeast, including: recovery of viable yeast for
reuse in the fermentation process, sale to animal feed processors, distillation to recover residual
ethanol, and disposal as process wastewater.
After the beer is aged, solids are typically removed by centrifugation or filtration with
diatomaceous earth filters, and the beer is pumped to final storage (beer storage tanks). From final
storage, the beer is pumped to the packaging (canning and bottling) facility.
Packaging facilities typically include several canning and bottling lines, as well as a keg filling
operation. Most facilities pasteurize beer after canning or bottling, although some facilities package
nonpasteurized products using sterile filling lines. Beer that spills during packaging is typically
collected by a drainage system, and can be processed to remove or recover ethanol before discharge
as process wastewater. Damaged and partially filled cans and bottles are typically collected, crushed,
and recycled. Beer from the damaged cans and bottles can be processed to remove or recover ethanol
before discharge as industrial sewage. The final steps in the process are labeling, packaging for
distribution, and shipping.
9.12.1-6 EMISSION FACTORS 10/96
-------
Microbreweries typically produce beer for on-site consumption, although some have limited
local keg distribution. The beer production process is similar to that of large breweries, although
several processes may be excluded or combined. Most microbreweries purchase bags of either malted
barley or malt flour for use in beer making. Malt flour requires no processing and is added directly
to the mash tun. The facilities that use malted barley typically have a small "cracker" that cracks the
grain prior to mashing. Brewhouse operations (mashing, brewers grain settling, brewing, and trub
settling) may be combined to decrease the number of tanks required. Fermentation tanks and storage
tanks are much smaller than large brewery tanks, with capacities as small as a few barrels. Many
microbrews are held in fermentation tanks for three to four weeks (far longer than most mass-
produced beers). Canning and bottling operations typically are not found in microbreweries.
9.12.1.2 Emissions And Controls1'4
Ethanol is the primary volatile organic compound (VOC) emitted from the production of malt
beverages. Aldehydes, ethyl acetate, other VOCs, CO2, and particulate matter (PM) are also
generated and potentially emitted.
Potential VOC emission sources include mash tuns, cereal cookers, lauter tuns or
strainmasters, brew kettles, hot wort settling tanks, yeast storage and propagation (see AP-42
Section 9.13.4), fermenters, spent grain holding tanks, activated charcoal regeneration systems (at
breweries with CO2 recovery), aging tanks (sometimes referred to as "rub." storage tanks), other
storage tanks, and packaging operations. The operations that precede fermentation are sources of
various species of VOC. Post-fermentation operations emit primarily ethanol; however, small
quantities of ethyl acetate and various aldehydes may also be emitted from fermenters and post-
fermentation operations. Other VOC that are emitted from cooking processes (mash tuns, hot wort
tanks, and brew kettles) may include dimethyl sulfide, C5-aldehydes, and myrcene (a hop oil emitted
from brew kettles).
Fermenters are a source of ethanol, other VOC, and CO2; large breweries typically recover
CO2 for internal use. However, smaller breweries and microbreweries typically vent CO2 to the
atmosphere.
Potential sources of PM emissions from breweries include grain malting, grain handling and
processing operations (see AP-42 Section 9.9,1), brewhouse operations, and spent-grain drying.
Emissions from microbreweries consist of the same pollutants as large brewery emissions.
No test data are available to quantify these emissions, but they are expected to be negligible based on
the amount of beer produced in these facilities. Emission control devices are not typically used by
microbreweries.
Process loss controls are used to reduce emissions from malt beverage production. Add-on
emission controls are used to recover CO2 in the fermentation process and to control PM emissions
from grain handling and brewers grain drying. Large breweries typically use CO2 recovery systems,
which can include water scrubbers or activated carbon beds to remove impurities from the CO2. The
scrubber water is typically discharged as process wastewater, and organic impurities collected by the
activated carbon beds are typically released to the atmosphere.
Water scrubbers could potentially be used to control ethanol emissions. However, scrubber
efficiency is based, in part, on the pollutant concentration (200 to 300 parts per million by volume
[ppmv] is needed for minimal efficiency), and the ethanol concentrations in fermentation rooms are
10/96 Food And Agricultural Industry 9.12.1-7
-------
typically very low (about 100 ppmv). Incineration is also an inefficient control measure if pollutant
concentrations are low. Recovery of ethanol vapor by carbon adsorption or other methods is another
control alternative, although the cost of recovery may be high.
Grain handling and processing operations (unloading, conveying, milling, and storage) are
typically controlled by fabric filters. Many smaller breweries purchase malt flour, and do not have
milling operations.
Each brewery is unique, and source to source variations can significantly affect emissions.
These variations result from differences in the brewing process, the type and age of equipment used,
and total production. Brewery emissions are also affected by the unique recipes and time and
temperature differences during various stages of production.
Emission factors for malt beverage production operations are shown in Tables 9.12.1-1 and
9.12.1-2.
Table 9.12.1-1. EMISSION FACTORS FOR MALT BEVERAGES*
Source/control
Brew kettleb
(SCC 3-02-009-07)
Brewers grain dryer
(SCC 3-02-009-30.-32)
Brewers grain dryer with
wet scrubber
(SCC 3-02-009-30,-32)
Filterable PM
PM
0.41
26C
0.42°
EMISSION
FACTOR
RATING
E
D
D
PM-10
ND
0.33d
0.1 ld
EMISSION
FACTOR
RATING
D
D
PM-2.5
ND
0.09 ld
0.060d
EMISSION
FACTOR
RATING
D
D
a Emission factor units are Ib of pollutant per 1,000 bbl of beer packaged unless noted.
1 bbl = 31 U.S. gallons. ND = no data available. SCC = Source Classification Code.
b Reference 9.
c References 11,13,17. Emission factor units are Ib of pollutant per ton of dried grain produced.
d Reference 11. Emission factor units are Ib of pollutant per ton of dried grain produced.
9.12.1-8
EMISSION FACTORS
10/96
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Table 9.12.1-2. EMISSION FACTORS FOR MALT BEVERAGES*
EMISSION FACTOR RATING: E
Process
Activated carbon regeneration0
(SCC 3-02-009-39)
Aging tank—filling*1
(SCC 3-02-009-08)
Bottle crusher6
(SCC 3-02-009-61)
Bottle crusher with water sprays6
(SCC 3-02-009-61)
Bottle filling linef
(SCC 3-02-009-53)
Bottle soaker and cleaner8
(SCC 3-02-009-60)
Brew kettleh
(SCC 3-02-009-07)
Brewers grain dryer—natural gas-fired
(SCC 3-02-009-30)
Brewers grain dryer-steam-heated
(SCC 3-02-009-32)
Can crusher with pneumatic conveyor"
(SCC 3-02-009-62)
Can filling linef
(SCC 3-02-009-51)
Cereal cookerp
(SCC 3-02-009-22)
Fermenter venting: closed fermenterq
(SCC 3-02-009-35)
Hot wort settling tankr
(SCC 3-02-009-24)
Keg filling line8
(SCC 3-02-009-55)
Lauter tunp
(SCC 3-02-009-23)
Mash tunp
(SCC 3-02-009-21)
Open wort cooler1"
(SCC 3-02-009-25)
Sterilized bottle filling line
(SCC 3-02-009-54)
Sterilized can filling line
(SCC 3-02-009-52)
CO
ND
ND
ND
ND
ND
ND
ND
ND
0.22m
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
CO2
ND
26
ND
ND
ND
ND
ND
840
53m
ND
ND
ND
2,100
ND
46
ND
ND
ND
4,300l
1,900*
vocb
0.035
0.57
0.48
0.13
17
0.20
0.64
0.73k
0.73k
0.088
14
0.0075
2.0
0.075
0.69
0.0055
0.054
0.022
40U
35U
Hydrogen
Sulfide
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.015
ND
ND
ND
ND
ND
ND
ND
10/96
Food And Agricultural Industry
9.12.1-9
-------
Table9.12.1-2(cont.).
Process
Trub vessel—filling1"
(SCC 3-02-009-26)
Waste beer storage tanks
(SCC 3-02-009-65)
CO
ND
ND
CO2
ND
ND
vocb
0.25
ND
Hydrogen
Sulfide
ND
ND
m
Emission factor units are Ib of pollutant per 1,000 bbl of beer packaged unless noted.
1 bbl = 31 U.S. gallons. ND = no data available. SCC = Source Classification Code.
Total organic compounds measured using EPA Method 25A, unless noted otherwise.
Pre-fermentation factors are presented as VOC as propane; post-fermentation factors are presented
as VOC as ethanol because the emissions have been shown to be primarily ethanol.
Reference 19. From CO2 recovery and purification system on a closed fermenter.
Reference 6. VOC as ethanol. EMISSION FACTOR RATING: D.
Reference 15. VOC as ethanol. Emission factor units are Ib of pollutant per batch of bottles
crushed. Crusher averages about 34 crushes per day.
Reference 20. Emission factor represents ethanol emissions measured using both EPA Method 18
and an FTIR analyzer. Factor is reported as VOC because ethanol is essentially the only VOC
emitted from filling operations.
Reference 14. Emission factor units are Ib of pollutant per 1000 cases of bottles washed.
Emission factor represents ethanol emissions measured by GC/FID. Factor is reported as VOC
because ethanol is essentially the only VOC emitted from this operation. EMISSION FACTOR
RATING: D.
References 9,19. VOC as propane.
Reference 17. Emission factor units are Ib of pollutant per ton of dried grain produced. Emission
factor includes data from dryers controlled by wet scrubbers, which do not control CO2 emissions.
EMISSION FACTOR RATING: D
References 11-13. VOC as propane. Emission factor units are Ib of pollutant per ton of dried
grain produced. Emission factor includes data from dryers controlled by wet scrubbers, which do
not control VOC emissions. EMISSION FACTOR RATING: D.
Reference 11. Emission factor units are Ib of pollutant per ton of dried grain produced. Emission
factor includes data from dryers controlled by wet scrubbers, which do not control CO or CO2
emissions. EMISSION FACTOR RATING: D.
Reference 16. VOC as ethanol. Emission factor units are Ib of pollutant per gallon of beer
recovered. EMISSION FACTOR RATING: D.
Reference 19. VOC as propane.
Reference 10. VOC as ethanol. Emission factors are based on a 24-hour venting period prior to
CO2 collection.
Reference 5. VOC as propane.
Reference 5. VOC as ethanol. EMISSION FACTOR RATING: D.
References. EMISSION FACTOR RATING: D.
References 5,7-8,18. VOC as ethanol. Emission factor includes measurements of VOC as ethanol
measured using EPA Method 25A and ethanol measured using both EPA Method 18 and an FTIR
analyzer. EMISSION FACTOR RATING: D.
9.12.1-10
EMISSION FACTORS
10/96
-------
References For Section 9.12.1
1. Written communication from Brian Shrager, Midwest Research Institute, Gary, NC, to
Dallas Safriet, U.S. Environmental Protection Agency, Research Triangle Park, NC, May 5,
1994.
2. Richard D. Rapoport et al., Characterization Of Fermentation Emissions From California
Breweries, Science Applications, Inc., Los Angeles, CA, October 26, 1983.
3. Written communication from Jere Zimmerman, Adolph Coors Company, Golden, CO, to
David Reisdorph, Midwest Research Institute, Kansas City, MO, March 11, 1993.
4. Written communication from Arthur J. DeCelle, Beer Institute, Washington, D.C., to
Dallas Safriet, U. S. Environmental Protection Agency, Research Triangle Park, NC,
February 15, 1995.
5. Report On Compliance Testing Performed For Coors Brewing Company, Clean Air
Engineering, Palatine, IL, November 25, 1992.
6. Report On Diagnostic Testing Performed For Coors Brewing Company, Revision 1, Clean Air
Engineering, Palatine, IL, April 6, 1994.
7. Can And Bottle Fitter Vent Volatile Organic Compound Test For Coors Brewing Company,
Air Pollution Testing, Inc., Westminster, CO, October 1992.
8. Filler Rooms Diagnostic VOC Test Report For Coors Brewing Company, Air Pollution
Testing, Inc., Westminster, CO, December 1992.
9. Stack Emissions Survey, Adolph Coors Company Brewery Complex, Golden, Colorado,
Western Environmental Services and Testing, Inc., Casper, WY, November, 1990.
10. Stack Emissions Survey, Adolph Coors Company Fermentation - Aging Facilities, Golden,
Colorado, Western Environmental Services and Testing, Inc., Casper, WY, November 1990.
11. Stack Emissions Survey, Adolph Coors Company Brewery Complex, Golden, Colorado,
Western Environmental Services and Testing, Inc., Casper, WY, February 1991.
12. Grain Dryer Diagnostic VOC Report For Coors Brewing Company, Air Pollution Testing,
Inc., Westminster, CO, November 1992.
13. Report On Compliance Testing Performed For Coors Brewing Company, Clean Air
Engineering, Palatine, IL, November 25, 1992.
14. Bottle Wash Soaker Area Ethanol Emissions Source Test Report Performed For Coors Brewing
Company, Acurex Environmental Corporation, Anaheim, CA, July 12, 1993.
15. Volatile Organic Compound Emissions Source Test Report For Coors Brewing Company, Air
Pollution Testing, Inc., Lakewood, CO, August 1993.
10/96 Food And Agricultural Industry 9.12.1-11
-------
16. Crushed Can Conveyor Unit Compliance VOC Test Report For Coors Brewing Company, Air
Pollution Testing, Inc., Lakewood, CO, October 21, 1993.
17. Emission Test Report, Dryers #1 And #4, Anheuser Busch, Inc., Columbus, Ohio, Pollution
Control Science, Miamisburg, OH, December 20, 1983.
18. Source Emissions Testing Report For Coors Brewing Company: Golden, Colorado Facility,
FID/FTIR Ethanol Measurements-Can And Bottle Line Ducts, Air Pollution Testing, Inc.,
Lakewood, CO, April 3-4, 1995.
19. Air Emissions Investigation Report, Miller Brewing Company, Fulton, New York, RTP
Environmental Associates, Inc., Westbury, NY, February 1994.
20. Stationary Source Sampling Report Reference No. 21691, Anheuser-Busch Brewery, Fort
Collins, Colorado, Filling Room Vents, Entropy, Inc., Research Triangle Park, NC,
July 26-28, 1994.
21. Emission Factor Documentation For AP-42 Section 9.12.1, Malt Beverages, Midwest
Research Institute, Gary, NC, October 1996.
9.12.1-12 EMISSION FACTORS 10/96
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9.12.2 Wines And Brandy
9.12.2.1 General
Wine is an alcoholic beverage produced by the fermentation of sugars in fruit juices,
primarily grape juice. In general, wines are classified into two types based on alcohol content: table
wines (7 percent to 14 percent, by volume) and dessert wines (14 percent to 24 percent, by volume).
Table wines are further subdivided into still and sparkling categories, depending upon the carbon
dioxide (CO;,) content retained in the bottled wine. Still table wines are divided into three groups:
red, rose" (blush), and white, based on the color of the wine.
1-4
9.12.2.2 Process Description
The production of still table wines is discussed in the following paragraphs, followed by more
concise discussions of the production of sweet table wines, sparkling wines, dessert wines, and
brandy.
Still Table Wines -
The basic steps in vinification (wine production) include harvesting, crushing, pressing,
fermentation, clarification, aging, finishing, and bottling. A simplified process diagram outlining the
basic steps in the production of still table wines is shown in Figure 9.12.2-1.
Harvesting of grapes is usually conducted during the cooler periods of the day to prevent or
retard heat buildup and flavor deterioration in the grape. Most wineries transport the whole grapes
but some crush the grapes in the vineyard and transport the crushed fruit to the winery. Stemming
and crushing are commonly conducted as soon as possible after harvest. These two steps are
currently done separately using a crusher-stemmer, which contains an outer perforated cylinder to
allow the grapes to pass through but prevents the passage of stems, leaves, and stalks. Crushing the
grapes after stemming is accomplished by any one of many procedures. The three processes
generally favored are: (1) pressing grapes against a perforated wall; (2) passing grapes through a set
of rollers; or (3) using centrifugal force. Generally, 25 to 100 milligrams (mg) of liquified sulfur
dioxide (SO2) are added per liter of the crushed grape mass to control oxidation, wild yeast
contamination, and spoilage bacteria.
Maceration is the breakdown of grape solids following crushing of the grapes. The major
share of the breakdown results from the mechanical crushing but a small share results from enzymatic
breakdown. In red and rose" wine production, the slurry of juice, skins, seeds, and pulp is termed the
"must". In white wine production, the skins, seeds, and pulp are separated from the juice before
inoculation with yeast and only the juice is fermented. A fermenting batch of juice is also called
"must". Thus, the term "must" can refer to either the mixture of juice, seeds, skins, and pulp for red
or rose wines or only the juice for white wines. Maceration is always involved in the initial phase of
red wine fermentation. The juice from the grapes may be extracted from the "must" in a press.
Additionally, gravity flow juicers may be used initially to separate the majority of the juice from the
crushed grapes and the press used to extract the juice remaining in the mass of pulp, skins, and seeds
(pomace). There are many designs of dejuicers but, generally, they consist of a tank fitted with a
perforated basket at the exit end. After gravity dejuicing has occurred, the pomace is placed in a
press and the remaining juice extracted. There are three major types of presses. The horizonal press
is used for either crushed or uncrushed grapes. A pneumatic press can be used for either crushed or
10/95 Food And Agricultural Products 9.12.2-1
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EMISSION FACTORS
10/95
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uncrushed grapes as well as for fermented "must". In the continuous screw press, the "must" is
pumped into the press and forced in the pressing chamber where perforated walls allow the juice to
escape. After pressing, white "must" is typically clarified and/or filtered prior to fermentation to
retain the fruity character. The white juice is commonly allowed to settle for up to 12 hours but may
be centrifuged to speed the clarification.
Fermentation is the process whereby the sugars (glucose and fructose) present in the "must"
undergo reaction by yeast activity to form ethyl alcohol (ethanol) and CO2 according to the equation:
C6H12O6 -» 2 C2H5OH + 2 CO2
In the U. S., the sugar content of the juice is commonly measured with a hydrometer in units
of degree Brix (°B), which is grams (g) of sugar per 100 grams of liquid. Fermentation may be
initiated by the addition of yeast inoculation to the "must". The fermentation process takes place in
tanks, barrels, and vats of a wide variety of shapes, sizes, and technical designs. Tanks are different
from vats in that tanks are enclosed, whereas vats have open tops. In most of the larger wineries,
tanks have almost completely replaced vats. Since the 1950s, the move has been away from the use
of wooden tanks, primarily to stainless steel tanks. Lined concrete tanks are also used, and fiberglass
tanks are becoming more popular because of their light weight and lower cost.
The fermentation process is an exothermic reaction and requires temperature control of the
fermenting "must". Red wines are typically fermented at 25° to 28°C (70° to 82°F) and white wines
at 8° to 15°C (46° to 59°F). Almost all of the fermentation is conducted by the batch process and
continuous fermentors are rarely used in the U. S. Size of the fermentors is based primarily on the
volume of "must" to be fermented. During fermentation of red wines, the CO2 released by the yeast
metabolism becomes entrapped in the pomace (layer of skins and seeds) and causes it to rise to the
top of the tank where it forms a cap. The pomace cap is periodically covered with the "must" to
increase color removal, aerate the fermenting "must", limit growth of spoilage organisms in the cap,
and help equalize the temperature in the fermenting "must". For white wines, the main technical
requirement is efficient temperature control. Temperature is one of the most influential factors
affecting the fermentation process. During fermentation of both white and red "must", the CO2,
water vapor, and ethanol are released through a vent in the top of the tank. Malolactic fermentation
sometimes follows the primary fermentation and results in a reduction in acidity and increased pH.
There are very diverse opinions about this step because the fermentation, to varying degrees, can
improve or reduce wine quality.
After fermentation, all wines undergo a period of adjustment (maturation) and clarification
prior to bottling. The process of maturation involves the precipitation of paniculate and colloidal
material from the wine as well as a complex range of physical, chemical, and biological changes that
tend to maintain and/or improve the sensory characteristics of the wine. The major adjustments are
acidity modification, sweetening, dealcoholization, color adjustment, and blending. Following the
fermentation process, a preliminary clarification step is commonly accomplished by decanting the
wine from one vessel to another, called racking, in order to separate the sediment (lees) from the
wine. Current racking practices range from manually decanting wine from barrel to barrel to highly
sophisticated, automated, tank-to-tank transfers. In all cases, separation occurs with minimal agitation
to avoid resuspending the particulate matter. The residue from racking may be filtered to recover
wine otherwise lost with the lees or may be used "as is" for brandy production.
Stabilization and further clarification steps follow maturation and initial clarification to
produce a permanently clear wine with no flavor faults. The steps entail various stabilization
10/95 Food And Agricultural Products , 9.12.2-3
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procedures, additional clarification (fining), and a final filtration prior to bottling. The most common
stabilization technique used for many red wines and some white wines is aging the wine for a period
of months or years. Vessels used to store and age wine, termed cooperage, are produced in a wide
range of sizes, depending on their intended use. White oak has traditionally been used for the barrels
to age wine, but currently its usage is reserved primarily for the production of premium white and red
wines and some fortified wines. Water and ethanol are lost through the barrel surfaces and a partial
vacuum develops in the space created by this loss. Each barrel is periodically opened and topped off
with wine to fill the void created by the ethanol and water loss. Cooperage constructed from
materials other than wood has many advantages and is less expensive to maintain. Stainless steel is
often preferred, but fiberglass and concrete are also used. In addition to aging, other stabilization
procedures are used to prevent formation of potassium bitartrate or calcium tartrate crystals, haziness
(casse) resulting from protein coalescence, casse resulting from oxidation of tannins present in the
wine, and haziness due to metal ions such as iron and copper. Enzyme mixtures are used to remove
polysaccharides which can cause filtration problems and haze formation. Most wines contain viable
but dormant microorganisms. Racking is used as an initial step in microbial stabilization but long-
term stability frequently requires use of sulfur dioxide as the antimicrobial agent. Other methods
include pasteurization and filter sterilization. Sulfur dioxide may be added at various stages in wine
production to prevent microbial growth and oxidation. Finishing (fining) agents are commonly added
to accelerate the precipitation of suspended material in wine. Prior to bottling, a final clarification
step is used to remove any remaining suspended material and microbes in the wine. This step
involves only physical methods of clarification, generally a filtration procedure.
Glass bottles are the container of choice for premium quality wines and for sparkling wines.
Because of disadvantages such as weight and breakage, glass bottles are sometimes being replaced by
new containers, such as bag-in-box, for many standard quality, high volume wines. To protect the
wine against microbial spoilage, and to limit oxidation, the SO2 content in the wine is adjusted to a
final level of 50 mg/L before filling. Precaution is taken to minimize contact with air during filling
and thereby to reduce oxidation. This is done by either flushing the bottle with inert gas before
filling or flushing the headspace with inert gas after filling.
Sweet Table Wines -
The most famous of the sweet wines are those made from noble-rotted, Botrytis-infected
grapes. These wines are produced to a limited extent in the United States. The Botrytis mold acts to
loosen the grape's skin so moisture loss occurs rapidly and the sugar concentration increases in the
grape. The grapes are then selectively picked, followed by pressing, and fermentation. Fermentation
is a slow process, however, because of the high sugar content and the use of SO2 to retard the growth
of undesirable molds and microorganisms. Nonbotrytized sweet wines are also produced by drying
the grapes. Drying involves allowing the grapes to dehydrate on mats or trays in the shade for weeks
or months and then crushing the grapes and fermenting the concentrated juice. Heating, boiling, or
freezing is also used to concentrate juice for semisweet wines.
Sparkling Wines -
Most sparkling wines obtain CO2 supersaturation using a second alcoholic fermentation,
typically induced by adding yeast and sugar to dry white wine. There are three principal methods of
sparkling wine production: the methode champagnoise, the transfer method, and the bulk method. In
the methode champagnoise, both red and white grapes may be used, but most sparkling wines are
white. The grapes are harvested earlier than those used for still table wines and pressed whole
without prior stemming or crushing to extract the juice with a minimum of pigment and tannin
extraction. This is important for producing white sparkling wines from red-skinned grapes. Primary
fermentation is carried out at approximately 15°C (59°F) and bentonite and/or casein may be added
9.12.2-4 EMISSION FACTORS 10/95
-------
to aid the process and improve clarity. The blending of wines produced from different sites,
varieties, and vintages distinguishes the traditional method. Before preparing the blend (cuvee), the
individual base wines are clarified and stabilized. Aging typically takes place in stainless steel tanks
but occasionally takes place in oak cooperage. The secondary fermentation requires inoculation of the
cuv&e wine with a special yeast strain. A concentrated sucrose solution is added to the cuv&e just
prior to the yeast inoculation. The wine is then bottled, capped, and stacked horizontally at a stable
temperature, preferably between 10° to 15°C (50° to 59°F), for the second fermentation. After
fermentation, the bottles are transferred to a new site for maturation and stored at about 10°C (50°F).
Riddling is the technique used to remove the yeast sediment (lees). The process involves
loosening and suspending the cells by manual or mechanical shaking and turning, and positioning the
bottle to move the lees toward the neck. Disgorging takes place about 1 or 2 years after bottling.
The bottles are cooled and the necks immersed in an ice/CaC!2 or ice/glycol solution to freeze the
sediment. The disgorging machine rapidly removes the cap on the bottle, allowing for ejection of the
frozen yeast plug. The mouth of the bottle is quickly covered and the fluid level is adjusted. Small
quantities of SO2 or ascorbic acid may be added to prevent subsequent in-bottle fermentation and limit
oxidation. Once the volume adjustment and other additions are complete, the bottles are sealed with
special corks, the wire hoods added, and the bottles agitated to disperse the additions. The bottles are
then decorated with their capsule and labels and stored for about 3 months to allow the corks to set in
the necks. The transfer method is identical to the methode champagnoise up to the riddling stage.
During aging, the bottles are stored neck down. When the aging process is complete, the bottles are
chilled below 0°C (32°F) before discharge into a transfer machine and passage to pressurized
receiving tanks. The wine is usually sweetened, sulfited, clarified by filtration, and sterile filtered
just before bottling.
In the bulk method, fermentation of the juice for the base wine may proceed until all the
sugar is consumed or it may be prematurely terminated to retain sugars for the second fermentation.
The yeast is removed by centrifugation and/or filtration. Once the cuvle is formulated, the wines are
combined with yeast additives and, if necessary, sugar. The second fermentation takes place in
stainless steel tanks similar to those used in the transfer process. Removal of the lees takes place at
the end of the second fermentation by centrifugation and/or filtration. The sugar and SO2 contents are
adjusted just before sterile filtration and bottling.
Other methods of production of sparkling wine include the "rural" method and carbonation.
The rural method involves prematurely terminating the primary fermentation prior to a second in-
bottle fermentation. The injection of CO2 (carbonation) under pressure at low temperatures is the
least expensive and the least prestigious method of producing sparkling wines.
Dessert Wines -
Dessert wines are classified together because of their elevated alcohol content. The most
common dessert wines are sherries and ports.
Baking is the most popular technique for producing sherries in the United States. Grapes are
crushed and stemmed and SO2 added as soon as possible to control bacteria and oxidation. The
maximum amount of juice is separated from the skins and the juice is transferred to fermentors. The
juice is inoculated with starter and fermented at temperatures of 25° to 30°C (77° to 86°F). The new
wine is then pumped from the fermentor or settling tank to the fortification tank. High proof spirits
are added to the sherry material, or shermat, to raise the alcohol content to 17 to 18 percent by
volume and then the wine is thoroughly mixed, clarified, and filtered before baking. Slow baking
occurs when the wine is stored in barrels exposed to the sun. More rapid baking is achieved through
10/95 Food And Agricultural Products 9.12.2-5
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the use of artificially heated storage rooms or heating coils in barrels or tanks. After baking, the
sherry is cooled, clarified, and filtered. Maturation is then required and is usually carried out in oak
barrels. Aging can last from 6 months to 3 years or more.
Port wines are produced by the premature termination of fermentation by addition of brandy.
When the fermenting must is separated from the pomace by gravity, it is fortified with wine spirits
containing about 77 percent alcohol, by volume. Most white ports are fortified when half the original
sugar content has been fermented, except for semidry and dry white ports which are fortified later.
The type and duration of aging depend on the desired style of wine. Blending is used to achieve the
desired properties of the wine. The final blend is left to mature in oak cooperage for several months
prior to fining, filtration, stabilization, and bottling.
Brandy Production —
Brandy is an alcoholic distillate or mixture of distillates obtained from the fermented juice,
mash, or wine from grapes or other fruit (e. g., apples, apricots, peaches, blackberries, or
boysenberries). Brandy is produced at less than 190° proof and bottled at a minimum of 80° proof.
(In the United States, "proof" denotes the ethyl alcohol content of a liquid at 15.6°C (60°F), stated as
twice the percent ethyl alcohol by volume.) Two types of spirits are produced from wine or wine
residue: beverage brandy and "wine spirits".
In brandy production, the grapes are pressed immediately after crushing. There are major
differences in the fermentation process between wine and brandy production. Pure yeast cultures are
not used in the fermentation process for brandy. Brandy can be made solely from the fermentation of
fruit or can be distilled either from the lees leftover from the racking process in still wine production
or from the pomace cap that is leftover from still red wine fermentations.
In the United States, distillation is commenced immediately after the fermentation step,
generally using continuous column distillation, usually with an aldehyde section, instead of pot stills.
For a detailed discussion of the distillation and aging of distilled spirits, which include brandy and
brandy spirits, refer to AP-42 Section 9.12.3, "Distilled And Blended Liquors". After distillation, the
brandy is aged in oak casks for 3 to 15 years or more. During aging, some of the ethanol and water
seep through the oak and evaporate, so brandy is added periodically to compensate for this loss.
Caramel coloring is added to give the brandy a characteristic dark brown color. After aging, the
brandy may be blended and/or flavored, and then chilled, filtered, and bottled.
9.12.2.3 Emissions And Controls5'11
Ethanol and carbon dioxide are the primary compounds emitted during the fermentation step
in the production of wines and brandy. Acetaldehyde, methyl alcohol (methanol), n-propyl alcohol,
n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, isoamyl alcohol, and hydrogen sulfide also are
emitted but in much smaller quantities compared to ethanol emissions. In addition, a large number of
other compounds are formed during the fermentation and aging process. Selected examples of other
types of compounds formed and potentially emitted during the fermentation process include a variety
of acetates, monoterpenes, higher alcohols, higher acids, aldehydes and ketones, and organosulfides.
During the fermentation step, large quantities of CO2 are also formed and emitted.
Fugitive ethanol emissions also occur during the screening of the red wine, pressing of the
pomace cap, aging in oak cooperage, and the bottling process. In addition, as a preservative, small
amounts of liquified SO2 are often added to the grapes after harvest, to the "must" prior to
9.12.2-6 EMISSION FACTORS 10/95
-------
fermentation, or to the wine after the fermentation is completed; SO2 emissions can occur during these
steps. There is little potential for VOC emissions before the fermentation step in wine production.
Except for harvesting the grapes and possibly unloading the grapes at the winery, there is
essentially no potential for particulate (PM) emissions from this industry.
Emission controls are not currently used during the production of wines or brandy. Five
potential control systems have been considered and three have been the subject of pilot-scale emission
test studies at wineries or universities in California. The five systems are (1) carbon adsorption,
(2) water scrubbers, (3) catalytic incineration, (4) condensation, and (5) temperature control. All of
the systems have disadvantages in either low control efficiency, cost effectiveness, or overall
applicability to the wide variety of wineries.
Emission factors for VOC and hydrogen sulfide emissions from the fermentation step in wine
production are shown in Table 9.12.2-1. The emission factors for controlled ethanol emissions and
the uncontrolled emissions of hydrogen sulfide and other VOCs from the fermentation step should be
used with caution because the factors are based on a small number of tests and fermentation
conditions vary considerably from one winery to another
The only emission factors for wine production processes other than fermentation, were
obtained from a 1982 test.7 These factors represent uncontrolled fugitive ethanol emissions during
handling processes. The factor for fugitive emissions from the pomace screening for red wine
(SCC 3-02-011-11) is 0.5 lb/1,000 gal of juice. An ethanol emission factor for the pomace press is
applicable only to red wine because the juice for white wine goes through the pomace press before the
fermentation step. The emission factor for red wine (SCC 3-02-011-12) is 0.02 Ib/ton of pomace.
Although fugitive emissions occur during the bottling of both red and white wines, an emission factor
is available only for the bottling of white wine. The factor for white wine bottling
(SCC 3-02-011-21) is 0.1 lb/1,000 gal of wine. All of these factors are rated E. These emission
factors should be used with extreme caution because they are based on a limited number of tests
conducted at one winery. There is no emission factor for fugitive emissions from the finishing and
stabilization step (aging).
There are no available data that can be used to estimate emission factors for the production of
sweet table wines, dessert wines, sparkling wines, or brandy.
10/95 Food And Agricultural Products 9.12.2-7
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References For Section 9.12.2
1. R. S. Jackson, Wine Science: Principles And Application, Academic Press, San Diego, CA,
1994.
2. M. A. Amerine, "Wine", in Kirk-Othmer Encyclopedia Of Chemical Technology, Third
Edition, Volume 24, John Wiley and Sons, New York, 1984.
3. J. A. Heredia, "Technical Assessment Document On Ethanol Emissions And Control From
California Wineries", Master of Science Dissertation, California Polytechnic State
University, San Luis Obispo, CA, June 1993.
4. M. A. Amerine, et al., Technology Of Wine Making, Fourth Edition, AVI Publishing
Company, Westport, CT, 1980.
5. G. C. Miller, et al., "Loss Of Aroma Compounds In Carbon Dioxide Effluent During White
Wine Fermentation", Food Technol. Aust., 39(5}:246-249, 1987.
6. Written communication from Dean C. Simeroth, California Air Resources Board, Sacramento,
CA, to Mark Boese, San Joaquin Valley Unified Air Pollution Control District, Fresno, CA,
November 1, 1994.
7. EAL Corporation, "Characterization Of Ethanol Emissions From Wineries", Final Report,
California Air Resources Board, Sacramento, CA, July, 1982.
8. Ethanol Emissions And Control For Wine Fermentation And Tanks, Report # ARB/ML-88-
027, California Air Resources Board, April 1988.
9. D.F. Todd, et al., "Ethanol Emissions Control From Wine Fermentation Tanks Using
Charcoal Adsorption: A Pilot Study", California Air Resources Board, published by
California Agricultural Technology Institute, March 1990.
10. Ethanol Emissions Control From Wine Fermentation Tanks Utilizing Carbon Adsorption
Technology, Akton Associates, Martinez, CA, June 1991.
11. Written communication from Arthur Caputi, Jr., E&J Gallo Winery, Modesto, CA, to Maria
Lima, San Joaquin Valley Unified Air Pollution Control District, Fresno, CA, December 14,
1992.
10/95 Food And Agricultural Products 9.12.2-9
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9.12.3 Distilled And Blended Liquors
[Work In Progress]
1/95 Food And Agricultural Industries 9.12.3-1
-------
9.12.3 Distilled Spirits
9.12.3.1 General1'2
The distilled spirits industry includes the production of whisky, gin, vodka, rum, and brandy. The
production of brandy is discussed in AP-42 Section 9.12.2, "Wines and Brandy". Distilled spirits
production also may include the production of secondary products such as distillers dried grains used for
livestock feed and other feed/food components.
Distilled spirits, including grain spirits and neutral spirits, are produced throughout the United
States.1 The Bureau of Alcohol, Tobacco, and Firearms (BATF) has established "standards of identity"
for distilled spirits products.2
9.12.3.2 Process Description3-4
Distilled spirits can be produced by a variety of processes. Typically, in whisky production,
grains are mashed and fermented to produce an alcohol/water solution, that is distilled to concentrate the
alcohol. For whiskies, the distilled product is aged to provide flavor, color, and aroma. This discussion
will be limited to the production of Bourbon whisky. Figure 9.12.3-1 is a simple diagram of a typical
whisky production process. Emission data are available only for the fermentation and aging steps of
whisky production.
9.12.3.2.1 Grain Handling And Preparation -
Distilleries utilize premium cereal grains, such as hybrid corn, rye, barley, and wheat, to produce
the various types of whisky and other distilled spirits. Grain is received at a distillery from a grain-
handling facility and is prepared for fermentation by milling or by malting (soaking the grains to induce
germination). All U.S. distillers purchase malted grain instead of performing the malting process onsite.
9.12.3.2.2 Grain Mashing -
Mashing consists of cooking the grain to solubilize the starch from the kernels and to convert the
soluble starch to grain sugars with barley malt and/or enzymes. Small quantities of malted barley are
sometimes added prior to grain cooking. The mash then passes through a noncontact cooler to cool the
converted mash prior to entering the fermenter.
9.12.3.2.3 Fermentation-
The converted mash enters the fermenter and is inoculated with yeast. The fermentation process,
which usually lasts 3 to 5 days for whisky, uses yeast to convert the grain sugars into ethanol and carbon
dioxide. Congeners are flavor compounds which are produced during fermentation as well as during the
barrel aging process. The final fermented grain alcohol mixture, called "beer", is transferred to a "beer
well" for holding. From the beer well, the beer passes through a preheater, where it is warmed by the
alcohol vapors leaving the still, and then to the distillation unit. The beer still vapors condensed in the
preheater generally are returned to the beer still as reflux.
3/97 Food And Agricultural Industry 9.12.3-1
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Grain Receding
(Malted Grains)
PM Emissions
Grain Handing
(3-02-010-01)
Milling
(3-02-01005)
Barley Mat.
or Enzymes
Grain Mashing
(Conversion of Starches to Sugars)
(302-010-13)
Yeast-
Fermentation
(Conversion of Sugars to Alcohol)
(302-010-14)
Backset Stillage
PM Emissions
OPTIONAL PROCESS
Grain Cleaning
(3-02-010-01)
„ PM Emissions j
•-•*• PM Emissions
-VOC Emisstonsa
Ethanol and COj Emissions'9
Backset Stillage
Whole Stillage
Dryer House Operations
(Distillers Dried Grains)
». PM Emissions3
Distillation
(3-02-010-15)
Intermediate Storage
VOC Emissions; Noncondensed Off-Gases3
Ethanol Emissions (Breathing)
Warehousing/Aging
(302010-17)
Intermediate Storage
Ethanol Emissions
Ethanol Emissions (Breathing)
Btending/Bottling
(34)2-010-18)
Ethanol Emissions
Processes require heat. Emissions generated (e.g., CO, CC>2, NOX, SO2, PM, and VOCs) will depend on the source of fuel.
5 Other compounds can be generated in trace quantities during fermentation including ethyl acetate, fusel oil, furfural,
acetaldehyde, sulfur dioxide, and hydrogen sutfide. Acetaldehyde is a hazardous air pollutant (HAP).
Figure 9.12.3-1. Whisky production process.
(Source Classification Codes in parentheses).
9.12.3-2
EMISSION FACTORS
3/97
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9,12.3.2.4 Distillation -
The distillation process separates and concentrates the alcohol from the fermented grain mash.
Whisky stills are usually made of copper, especially in the rectifying section, although stainless steel may
be used in some stills. Following distillation, the distilled alcohol spirits are pumped to stainless steel tanks
and diluted with demineralized water to the desired alcohol concentration prior to filling into oak barrels
and aging. Tennessee whisky utilizes a different process from Bourbon in that the distillate is passed
through sugar maple charcoal in mellowing vats prior to dilution with demineralized water.
9.12.3.2.5 Grain And Liquid Stillage ("Dryer House Operations") -
In most distilleries, after the removal of alcohol, still bottoms (called whole stillage), are pumped
from the distillation column to a dryer house. Whole stillage may be sold, land applied (with permitting),
sold as liquid feed, or processed and dried to produce distillers dried grains (DDG) and other secondary
products. Solids in the whole stillage are separated using centrifuges or screens; the liquid portion (thin
stillage) may be used as a backset or concentrated by vacuum evaporation. The concentrated liquid may
be recombined with the solids or dried. Drying is typically accomplished using either steam-heated or
flash dryers.
9.12.3.2.6 Warehousing/Aging -
Aging practices differ from distiller to distiller, and even for the same distiller. Variations in the
aging process are integral to producing the characteristic taste of a particular brand of distilled spirit. The
aging process, which typically ranges from 4 to 8 years or more, consists of storing the new whisky
distillate in oak barrels to encourage chemical reactions and extractions between the whisky and the wood.
The constituents of the barrel produce the whisky's characteristic color and distinctive flavor and aroma.
White oak is used because it is one of the few woods that holds liquids while allowing breathing (gas
exchange) through the wood. Federal law requires all Bourbon whisky to be aged in charred new white
oak barrels.
The oak barrels and the barrel environment are key to producing distilled spirits of desired quality.
The new whisky distillate undergoes many types of physical and chemical changes during the aging process
that removes the harshness of the new distillate. As whisky ages, it extracts and reacts with constituents in
the wood of the barrel, producing certain trace substances, called congeners, which give whisky its
distinctive color, taste, and aroma.
Barrel environment is extremely critical in whisky aging and varies considerably by distillery,
warehouse, and even location in the warehouse. Ambient atmospheric conditions, such as seasonal and
diurnal variations in temperature and humidity, have a great affect on the aging process, causing changes
in the equilibrium rate of extraction, rate of transfer by diffusion, and rate of reaction. As a result,
distillers may expose the barrels to atmospheric conditions during certain months, promoting maturation
through the selective opening of windows and doors and by other means.
Distillers often utilize various warehouse designs, including single- or multistory buildings
constructed of metal, wood, brick, or masonry. Warehouses generally rely upon natural ambient
temperature and humidity changes to drive the aging process. In a few warehouses, temperature is
adjusted during the winter. However, whisky warehouses do not have the capability to control humidity,
which varies with natural climate conditions.
9.12.3.2.7 Blending/Bottling -
Once the whisky has completed its desired aging period, it is transferred from the barrels into
tanks and reduced in proof to the desired final alcohol concentration by adding demineralized water.
3/97 Food And Agricultural Industry 9.12.3-3
-------
Following a filtration process that renders it free of any solids, the whisky is pumped to a tank in the
bottling house, bottled, and readied for shipment to the distributors.
9.12.3.3 Emissions And Controls3'6
9.12.3.3.1 Emissions -
The principal emissions from whisky production are volatile organic compounds (VOCs),
principally ethanol, and occur primarily during the aging/warehousing stage. In addition to ethanol, other
volatile compounds, including acetaldehyde (a HAP), ethyl acetate, glycerol, fusel oil, and furfural, may
be produced in trace amounts during aging. A comparatively small source of ethanol emissions may result
from the fermentation stage. Smaller quantities of ethyl acetate, isobutyl alcohol, and isoamyl alcohol are
generated as well; carbon dioxide is also produced during fermentation. Particulate matter (PM) emissions
are generated by the grain receiving, handling, drying, and cleaning processes and are discussed in more
detail in AP-42 Section 9.9.1, Grain Elevators and Processes. Other emissions, including S02, C02, CO,
NOX, and PM may be generated by fuel combustion from power production facilities located at most
distilled spirits plant.
Ethanol and water vapor emissions result from the breathing phenomenon of the oak barrels during
the aging process. This phenomenon of wood acting as a semipermeable membrane is complex and not
well understood. The emissions from evaporation from the barrel during aging are not constant. During
the first 6 to 18 months, the evaporation rate from a new barrel is low because the wood must become
saturated (known as "soakage") before evaporation occurs. After saturation, the evaporation rate is
greatest, but then decreases as evaporation lowers the liquid level in the barrel. The lower liquid level
decreases the surface area of the liquid in contact with the wood and thus reduces the surface area subject
to evaporation. The rate of extraction of wood constituents, transfer, and reaction depend upon ambient
conditions, such as temperature and humidity, and the concentrations of the various whisky constituents.
Higher temperatures increase the rate of extraction, transfer by diffusion, and reaction. Diurnal and
seasonal temperature changes cause convection currents in the liquid. The rate of diffusion will depend
upon the differences in concentrations of constituents in the wood, liquid, and air blanketing the barrel.
The rates of reaction will increase or decrease with the concentration of constituents. The equilibrium
concentrations of the various whisky components depend upon the humidity and air flow around the barrel.
Minor emissions are generated when the whisky is drained from the barrels for blending and
bottling. Residual whisky remains in the used barrels both as a surface film ("heel") and within the wood
("soakage"). For economic reasons, many distillers attempt to recover as much residual whisky as
possible by methods such as rinsing the barrel with water and vacuuming. Generally, barrels are refilled
and reentered into the aging process for other distilled spirits at the particular distiller or sealed with a
closure (bung) and shipped offsite for reuse with other distilled spirits. Emissions may also be generated
during blending and bottle filling, but no data are available.
9.12.3.3.2 Controls-
With the exception of devices for controlling PM emissions, there are very few emission controls
at distilleries. Grain handling and processing emissions are controlled through the use of cyclones,
baghouses, and other PM control devices (see AP-42 Section 9.9.1). There are currently no current
control technologies for VOC emissions from fermenters because the significant amount of grain solids
that would be carried out of the fermenters by air entrainment could quickly render systems, such as
carbon adsorption, inoperable. Add-on air pollution control devices for whisky aging warehouses are not
used because of potential adverse impact on product quality. Distillers ensure that barrel construction is of
high quality to minimize leakage, thus reducing ethanol emissions. Ethanol recovery would require the use
9.12.3-4 EMISSION FACTORS 3/97
-------
of a collection system to capture gaseous emissions in the warehouse and to process the gases through a
recovery system prior to venting them to the atmosphere.
9.12.3.3.3 Emission Factors-
Table 9.12.3-1 provides uncontrolled emission factors for emissions of VOCs from fermentation
vats and for emissions of ethanol from aging due to evaporation. Because ethanol is the principal VOC
emission from aging, the ethanol emissions factors are reasonable estimates of VOC emissions for these
processes. Emission factors for grain receiving, handling, and cleaning may be found in
AP-42 Section 9.9.1, Grain Elevators and Processes. Emission factors are unavailable for grain mashing,
distillation, blending/bottling, and spent grain drying. An emission factor for carbon dioxide from
fermentation vats is also unavailable, although carbon dioxide and ethanol are theoretically generated in
equal molecular quantities during the fermentation process.
Table 9.12.3-1. EMISSION FACTORS FOR DISTILLED SPIRITS3
EMISSION FACTOR RATING: E
Sourceb
Grain mashing
(SCC 3-02-010-13)
Fermentation vats
(SCC 3-02-010-14)
Distillation
(SCC 3-02-010-15)
Aging
(SCC 3-02-010-17)
Evaporation lossd
Blending/bottling
(SCC 3-02-010-18)
Dryer house operations
(SCC 3-02-010-02)
Ethanol
NA
14. 2C
ND
6.9e
ND
ND
Ethyl acetate
NA
0.046C
ND
ND
ND
ND
Isoamyl
Alcohol
NA
0.013C
ND
ND
ND
ND
Isobutyl .
Alcohol
NA
0.004C
ND
ND
ND
ND
a Factors represent uncontrolled emissions. SCC = Source Classification Code. ND = no data
available. To convert from Ib to kg, divide by 2.2. NA = not applicable.
b Emission factors for grain receiving, handling, and cleaning processes are available in
AP-42 Section 9.9.1, Grain Elevators and Processes.
c Reference 5 (paper). In units of pounds per 1,000 bushels of grain input.
d Evaporation losses during whisky aging do not include losses due to soakage.
e References 6-7. In units of Ib/bbl/yr; barrels have a capacity of approximately 53 gallons.
Recognizing that aging practices may differ from distiller to distiller, and even for different
products of the same distiller, a method may be used to estimate total ethanol emissions from barrels
during aging. An ethanol emission factor for aging (total loss emission factor) can be calculated based on
annual emissions per barrel in proof gallons (PG). The term "proof gallon" refers to a U.S. gallon of
proof spirits, or the alcoholic equivalent thereof, containing 50 percent of ethyl alcohol (ethanol) by
volume. This calculation method is derived from the gauging of product and measures the difference in
the amount of product when the barrel was filled and when the barrel was emptied. Fugitive evaporative
3/97
Food And Agricultural Industry
9.12.3-5
-------
emissions, however, are not the sole difference between these two amounts. During the aging period,
product soaks into the barrel, test samples are drawn, and other losses (e. g., spillage, leakage) may occur.
Estimates of ethanol loss due to evaporation during aging based only on the gauging of product will
produce an overestimate unless soakage and sampling losses (very small losses) are subtracted. The
emission factor for evaporation loss in Table 9.12.3-1 represents an overestimate because only data for
soakage losses could be calculated; data for other losses were not available.
References for Section 9.12.3
1. Bureau Of Alcohol, Tobacco, And Firearms (BATF), "Monthly Statistical Release-Distilled
Spirits", Department Of The Treasury, Washington, DC, January 1995 through December 1995.
2. "Standards Of Identity For Distilled Spirits", 27 CFR Part 1, Subpart C, Office Of The Federal
Register, National Archives And Records Administration, Washington, D.C., April 1, 1996.
3. Bujake, J. E., "Beverage Spirits, Distilled", Kirk-Othmer Encyclopedia Of Chemical Technology,
4th. Ed., Volume No. 4, John Wiley & Sons, Inc., 1992.
4. Cost And Engineering Study Control Of Volatile Organic Emissions From Whiskey Warehousing,
EPA-450/2-78-013, Emissions Standards Division, Chemical and Petroleum Branch, Office Of
Air Quality Planning And Standards, U. S. Environmental Protection Agency, Research Triangle
Park, NC, April 1978.
5. Carter, R. V., and B. Linsky, "Gaseous Emissions From Whiskey Fermentation Units",
Atmospheric Environment, 8:57-62, January 1974; also a preliminary paper of the same title by
these authors (undated).
6. Written communication from R. J. Garcia, Seagrams Americas, Louisville, KY, to T. Lapp,
Midwest Research Institute, Gary, NC, March 3, 1997. RTGs versus age for 1993 standards.
7. Written communication from L. J. Omlie, Distilled Spirits Council Of The United States,
Washington, D.C., to T. Lapp, Midwest Research Institute, Gary, NC, February 6, 1997.
Ethanol emissions data from Jim Beam Brands Co.
9.12.3-6 EMISSION FACTORS 3/97
-------
9.13 Miscellaneous Food And Kindred Products
9.13.1 Fish Processing
9.13.2 Coffee Roasting
9.13.3 Snack Chip Deep Fat Frying
9.13.4 Yeast Production
1/95 Food And Agricultural Industries 9.13-1
-------
9.13.1 Fish Processing
9.13.1.1 General
Fish canning and byproduct manufacturing are conducted in 136 plants in 12 states. The
majority of these plants are in Washington, Alaska, Maine, Louisiana, and California. Some
processing occurs in Delaware, Florida, Illinois, Maryland, New York, and Virginia. The industry
experienced an 18 percent increase in the quantity of fish processed in 1990, and additional increases
were expected hi 1992 as well. Exports of canned fish and fish meal also are increasing because of
diminishing supply hi other countries.
9.13.1.2 Process Description
Fish processing includes both the canning of fish for human consumption and the production
of fish byproducts such as meal and oil. Either a precooking method or a raw pack method can be
used hi canning. In the precooking method, the raw fish are cleaned and cooked before the canning
step. In the raw pack method, the raw fish are cleaned and placed hi cans before cooking. The
precooking method is used typically for larger fish such as tuna, while the raw pack method is used
for smaller fish such as sardines.
The byproduct manufacture segment of the fish industry uses canning or filleting wastes and
fish that are not suitable for human consumption to produce fish meal and fish oil.
Canning -
The precooking method of canning (Figure 9.13.1-1) begins with thawing the fish, if
necessary. The fish are eviscerated and washed, then cooked. Cooking is accomplished using steam,
oil, hot air, or smoke for 1.5 to 10 hours, depending on fish size. Precooking removes the fish oils
and coagulates the protein hi the fish to loosen the meat. The fish are then cooled, which may take
several hours. Refrigeration may be used to reduce the cooling time. After cooling, the head, fins,
bones, and undesirable meat are removed, and the remainder is cut or chopped to be put hi cans.
Oil, brine, and/or water are added to the cans, which are sealed and pressure cooked before shipment.
The raw pack method of canning (Figure 9.13.1-2) also begins with thawing and weighing the
fish. They are then washed and possibly brined, or "nobbed", which is removing the heads, viscera,
and tails. The fish are placed hi cans and then cooked, drained, and dried. After drying, liquid,
which may be oil, brine, water, sauce, or other liquids, is added to the cans. Finally, the cans are
sealed, washed, and sterilized with steam or hot water.
Byproduct Manufacture -
The only process used in the U. S. to extract oil from the fish is the wet steam process. Fish
byproduct manufacturing (Figure 9.13.1-3) begins with cooking the fish at 100°C (lower for some
species) hi a continuous cooker. This process coagulates the protein and ruptures the cell walls to
release the water and oil. The mixture may be strained with an auger hi a perforated casing before
pressing with a screw press. As the fish are moved along the screw press, the pressure is increased
and the volume is decreased. The liquid from the mixture, known as pressing liquor, is squeezed out
through a perforated casing.
1/95 Food And Agricultural Industries 9.13.1-1
-------
VOC Emissions
Thawed
Whole Fish
Evisceration
and Washing
t
Precooking with
Steam, Hot Air, Oil,
Water, or Smoke
(SCC 3-02-012-04)
Refrigeration
In Air
1
Removal of Heads,
Fins, Bones, etc.
Sealing and
Retorting
Addition of Oil
Brine, or Water
Placement in
Cans
i
Cutting or
Chopping
Figure 9.13.1-1. Flow diagram of precooking method.
(Source Classification Codes in parentheses.)
9.13.1-2
EMISSION FACTORS
1/95
-------
o>
CO
g
'
o
5
"F 09
.5 co
tO 03
OS
UJ
O)
Cooking
(SCC 3-02-012-04)
i
c
0>
t
to
(0
go
CO
o_
i
k
O D)
OV^
|S
.? 0
mz
= CD
(0
o>
«o
^
ll
11
*-1
o 8
00
O
cs
»
1/95
Food And Agricultural Industries
9.13.1-3
-------
voc
Emissions (1)
Raw Fish
and Fish Parts
t
Cooker
(SCC 3-02-012-01)
(SCC 3-02-012-02)
VOC and Participate
Emissions (2)
VOC and
Participate
Emissions (3)
, but no particulates
(1) VOC emissions consist of H2S and
(2) Large odor source, as well as smoke
(3) Slightly less odor than direct fired dryers, and no smoke
Figure 9.13.1-3. Flow diagram of fish meal and crude fish oil processing.
(Source Classification Codes in parentheses.)
9.13.1^
EMISSION FACTORS
1/95
-------
The pressing liquor, which consists of water, oil, and some solids, is transported to a
centrifuge or desludger where the solids are removed. These solids are later returned to the press
cake in the drying step. The oil and water are separated using a disc-type centrifuge in the oil
separator. The oil is "polished" by using hot water washes and centrifugation and is then sent to an
oft-refining operation. The water removed from the oil (stickwater) goes to an evaporator to
concentrate the solids.
The press cake, stickwater, and solids are mixed and sent to either a direct-fired or an
indirect-fired dryer (steam tube dryer). A direct-fired dryer consists of a slowly rotating cylinder
through which air, heated to about 600 °C by an open flame, passes through the meal to evaporate the
liquid. An indirect-fired dryer consists of a fixed cylinder with rotating scrapers that heat the meal
with steam or hot fluids flowing through discs, tubes, coils, or the dryer casing itself. Air also passes
through this apparatus, but it is not heated and flows in the opposite direction to the meal to entrain
the evaporated water. Indirect-fired dryers require twice as much tune to dry the meal as direct-fired
dryers.
The dried meal is cooled, ground to a size that passes through a U. S. No. 7 standard screen,
and transferred by pneumatic conveyor to storage. The ground meal is stored in bulk or in paper,
burlap, or woven plastic bags. This meal is used in animal and pet feed because of its high protein
content.
The "polished oil" is further purified by a process called "hardening" (Figure 9.13.1-4).
First, the polished oil is refined by mixing the oil with an alkaline solution in a large stirred vat. The
alkaline solution reacts with the free fatty acids in the oil to form insoluble soaps. The mixture is
allowed to settle overnight, and the cleared oil is extracted off the top. The oil is then washed with
hot water to remove any remaining soaps.
Crude Oil
>.
•
Refining
Vat1
>.
Bleaching
Hardened Oil
Bottling and Storage
Figure 9.13.1-4. Oil hardening process.
Bleaching occurs hi the next step by mixing the oil with natural clays to remove oil pigments
and colored matter. This process proceeds at temperatures between 80 and 116°C, in either a batch
or continuous mode. After bleaching, hydrogenation of the unsaturated fatty acid chains is the next
1/95
Food And Agricultural Industries
9.13.1-5
-------
step. A nickel catalyst, at a concentration of 0.05 to 0.1 percent by weight, is added to a vat of oil,
the mixture is heated and stirred, and hydrogen is injected into the mixture to react with the
unsaturated fatty acid chains. After the hydrogenation is completed, the oil is cooled and filtered to
remove the nickel.
The hydrogenated oil is refined again before the deodorization step, which removes odor and
flavor-producing chemicals. Deodorization occurs in a vacuum chamber where dry, oxygen-free
steam is bubbled through the oil to remove the undesirable chemicals. Volatilization of the
undesirable chemicals occurs at temperatures between 170 to 230°C. The oil is then cooled to about
38°C before exposure to air to prevent formation of undesirable chemicals.
9.13.1.2 Emissions And Controls
Although smoke and paniculate may be a problem, odors are the most objectionable emissions
from fish processing plants. The fish byproducts segment results in more of these odorous
contaminants than canning, because the fish are often in a further state of decomposition, which
usually results in greater concentrations of odors.
The largest odor source in the fish byproducts segment is the fish meal driers. Usually,
direct-fired driers emit more odors than steam-tube driers. Direct-fired driers also emit smoke and
paniculate.
Odorous gases from reduction cookers consist primarily of hydrogen sulfide (H2S) and
trimethylamine [(CH3)3N] but are emitted from this stage in appreciably smaller volumes than from
fish meal driers. There are virtually no paniculate emissions from reduction cookers.
Some odors are produced by the canning processes. Generally, the precooked method emits
fewer odorous gases than the raw pack method. In the precooked process, the odorous exhaust gases
are trapped in the cookers, whereas hi the raw pack process, the steam and odorous gases typically
are vented directly to the atmosphere.
Fish cannery and fish byproduct processing odors can be controlled with afterburners,
chlorinator-scrubbers, or condensers. Afterburners are most effective, providing virtually 100 percent
odor control, but they are costly from a fuel-use standpoint. Chlorinator scrubbers have been found
to be 95 to 99 percent effective in controlling odors from cookers and driers. Condensers are the
least effective control device.
Paniculate emissions from the fish meal process are usually limited to the dryers, primarily
the direct-fired dryers, and to the grinding and conveying of the dried fish meal. Because there is a
relatively small quantity of fines in the ground fish meal, paniculate emissions from the grinding,
pneumatic conveyors and bagging operations are expected to be very low. Generally, cyclones have
been found to be an effective means to collect paniculate from the dryers, grinders and conveyors,
and from the bagging of the ground fish meal.
Emission factors for fish processing are presented in Table 9.13.1-1. Factors are expressed hi
units of kilograms per megagram (kg/Mg) and pounds per ton (Ib/ton).
9.13.1-6 EMISSION FACTORS 1/95
-------
Table 9.13.1-1 (Metric And English Units). UNCONTROLLED EMISSION FACTORS
FOR FISH CANNING AND BYPRODUCT MANUFACTURE8
EMISSION FACTOR RATING: C
Process
Cookers, canning
(SCC 3-02-012-04)
Cookers, scrap
Fresh fish (SCC 3-02-012-01)
Stale fish (SCC 3-02-012-02)
Steam tube dryer
(SCC 3-02-012-05)
Direct-fired dryer
(SCC 3-02-012-06)
Paniculate
kg/Mg
Neg
Neg
Neg
2.5
4
Ib/ton
Neg
Neg
Neg
5
8
Trimethylamine
[(CH3)3N]
kg/Mg
c
0.15C
1.75C
_b
_b
lb/ton
c
0.3°
3.5C
_b
_b
Hydrogen Sulfide
(H2S)
kg/Mg
c
0.005C
0.10°
__b
_b
lb/ton
c
0.01C
0.2C
__b
_b
a Reference 1. Factors are in terms of raw fish processed. SCC = Source Classification Code.
Neg = negligible.
b Emissions suspected, but data are not available for quantification.
c Reference 2.
References For Section 9.13.1
1. W. H. Prokop, "Fish Processing11, Air Pollution Engineering Manual, Van Nostrand
Reinhold, New York, 1992.
*
2. W. Summer, Methods Of Air Deodorization, Elsevier Publishing, New York City, 1963.
3. M. T. Gillies, Seafood Processing, Noyes Data Corporation, Park Ridge, NJ, 1971.
4. F. W. Wheaton and T. B. Lawson, Processing Aquatic Food Products, John Wiley and Sons,
New York, 1985.
5. M. Windsor and S. Barlow, Introduction To Fishery Byproducts, Fishing News Books, Ltd.,
Surrey, England, 1981.
6. D. Warne, Manual On Fish Canning, Food And Agricultural Organization Of The United
Nations, Rome, Italy, 1988.
1/95
Food And Agricultural Industries
9.13.1-7
-------
9.13.2 Coffee Roasting
9.13.2.1 General
The coffee roasting industry involves the processing of green coffee beans into roasted coffee
products, including whole and ground beans and soluble coffee products. The Standard Industrial
Classification (SIC) code for coffee roasting is 2095.
9.13.2.2 Process Description1'6
The coffee roasting process consists essentially of cleaning, roasting, cooling, grinding, and
packaging operations. Figure 9.13.2-1 shows a process flow diagram for a typical coffee roasting
operation. Bags of green coffee beans are hand- or machine-opened, dumped into a hopper, and
screened to remove debris. The green beans are then weighed and transferred by belt or pneumatic
conveyor to storage hoppers. From the storage hoppers, the green beans are conveyed to the roaster.
Roasters typically operate at temperatures between 370° and 540 °C (698° and 1004°F), and the beans
are roasted for a period of time ranging from a few minutes to about 30 minutes. Roasters are
typically horizontal rotating drums that tumble the green coffee beans in a current of hot combustion
gases; the roasters operate in either batch or continuous modes and can be indirect- or direct-fired.
Indirect-fired roasters are roasters in which the burner flame does not contact the coffee beans,
although the combustion gases from the burner do contact the beans. Direct-fired roasters contact the
beans with the burner flame and the combustion gases. At the end of the roasting cycle, water sprays
are used to "quench" the beans. Following roasting, the beans are cooled and run through a
"destoner". Destoners are air classifiers that remove stones, metal fragments, and other waste not
removed during initial screening from the beans. The destoners pneumatically convey the beans to a
hopper, where the beans are stabilize and dry (small amounts of water from quenching exist on the
surface of the beans). This stabilization process is called equilibration. Following equilibration, the
roasted beans are ground, usually by multi-stage grinders. Some roasted beans are packaged and
shipped as whole beans. Finally, the ground coffee is vacuum sealed and shipped.
Additional operations associated with processing green coffee beans include decaffeination and
instant (soluble) coffee production. Decaffeination is the process of extracting caffeine from green
coffee beans prior to roasting. The most common decaffeination process used in the United States is
supercritical carbon dioxide (CO2) extraction. In this process, moistened green coffee beans are
contacted with large quantities of supercritical CO2 (CO2 maintained at a pressure of about
4,000 pounds per square inch and temperatures between 90° and 100°C [194° and 212°F]), which
removes about 97 percent of the caffeine from the beans. The caffeine is then recovered from the
CO2, typically using an activated carbon adsorption system. Another commonly used method is
solvent extraction, typically using oil (extracted from roasted coffee) or ethyl acetate as a solvent. In
this process, solvent is added to moistened green coffee beans to extract most of the caffeine from the
beans. After the beans are removed from the solvent, they are steam-stripped to remove any residual
solvent. The caffeine is then recovered from the solvent, and the solvent is re-used. Water extraction
is also used for decaffeination, but little information on this process is available. Decaffeinated coffee
beans have a residual caffeine content of about 0.1 percent on a dry basis. Not all facilities have
decaffeination operations, and decaffeinated green coffee beans are purchased by many facilities that
produce decaffeinated coffee.
9/95 Food and Agricultural Products 9.13.2-1
-------
1
GREEN COFFEE BEAN
STORAGE AND
HANDLING
(SCO 3-02-002-08)
DECAFFEINATION
— o
t
( 1 ^
CAFFEINE EXTRACTS
(SCC!W>2-002-10,-11)
i
STEAM OR HOT AIR
DRYING
(SCC 3-02-002-1 8)
BATCH-(SCC 3-02-002-20.-24)
CONTINUOUS--(SCC 3-02-002-21 ,-2fc)
*• PRODUCT STREAM
«. EXHAUST STREAM
OPTIONAL PROCESS
PM EMISSIONS
VOC EMISSIONS
OTHER GASEOUS EMISSIONS
(CO, ttfe , METHANE, NO }
Figure 9.13.2-1. Typical coffee roasting operation.
(Source Classification Codes in parentheses.)
9.13.2-2
EMISSION FACTORS
9/95
-------
In the manufacture of instant coffee, extraction follows the roasting and grinding operations.
The soluble solids and volatile compounds that provide aroma and flavor are extracted from the coffee
beans using water. Water heated to about 175°C (347°F) under pressurized conditions (to maintain
the water as liquid) is used to extract all of the necessary solubles from the coffee beans.
Manufacturers use both batch and continuous extractors. Following extraction, evaporation or freeze-
concentration is used to increase the solubles concentration of the extract. The concentrated extracts
are then dried in either spray dryers or freeze dryers. Information on the spray drying and freeze
drying processes is not available.
9.13.2.3 Emissions And Controls
Paniculate matter (PM), volatile organic compounds (VOC), organic acids, and combustion
products are the principal emissions from coffee processing. Several operations are sources of PM
emissions, including the cleaning and destoning equipment, roaster, cooler, and instant coffee drying
equipment. The roaster is the main source of gaseous pollutants, including alcohols, aldehydes,
organic acids, and nitrogen and sulfur compounds. Because roasters are typically natural gas-fired,
carbon monoxide (CO) and carbon dioxide (CO^) emissions are expected as a result of fuel
combustion. Decaffeination and instant coffee extraction and drying operations may also be sources
of small amounts of VOC. Emissions from the grinding and packaging operations typically are not
vented to the atmosphere.
Paniculate matter emissions from the receiving, storage, cleaning, roasting, cooling, and
stoning operations are typically ducted to cyclones before being emitted to the atmosphere. Gaseous
emissions from roasting operations are typically ducted to a thermal oxidizer or thermal catalytic
oxidizer following PM removal by a cyclone. Some facilities use the burners that heat the roaster as
thermal oxidizers. However, separate thermal oxidizers are more efficient because the desired
operating temperature is typically between 650°C and 816°C (1200°F and 1500°F), which is 93°C to
260°C (200°F to 500°F) more than the maximum temperature of most roasters. Some facilities use
thermal catalytic oxidizers, which require lower operating temperatures to achieve control efficiencies
that are equivalent to standard thermal oxidizers. Catalysts are also used to improve the control
efficiency of systems in which the roaster exhaust is ducted to the burners that heat the roaster.
Emissions from spray dryers are typically controlled by a cyclone followed by a wet scrubber.
Table 9.13.2-1 presents emission factors for filterable PM and condensible PM emissions
from coffee roasting operations. Table 9.13.2-2 presents emission factors for volatile organic
compounds (VOC), methane, CO, and CO2 emissions from roasting operations. Emissions from
batch and continuous roasters are shown separately, but with the exception of CO emissions, the
emissions from these two types of roasters appear to be similar.
9/95 Food and Agricultural Products 9.13.2-3
-------
Table 9.13.2-1. EMISSION FACTORS FOR COFFEE ROASTING OPERATIONS"
EMISSION FACTOR RATING: D
Source
Batch roaster with thermal oxidizerb
(SCC 3-02-002-20)
Continuous cooler with cyclone0
(SCC 3-02-002-28)
Continuous roaster*
(SCC 3-02-002-21)
Continuous roaster with thermal oxidizer
(SCC 3-02-002-21)
Green coffee bean screening, handling, and
storage system with fabric filter'
(SCC 3-02-002-08)
Destoner
(SCC 3-02-002-30)
Equilibration
(SCC 3-02-002-34)
Filterable PM,
Ib/ton
0.12
0.028
0.66
0.092°
0.059
ND
ND
Condensible PM
Ib/ton
ND
ND
ND
0.10C
ND
ND
ND
" Emission factors are based on green coffee bean feed. Factors represent uncontrolled
emissions unless noted. SCC = Source Classification Code. ND = no data. D-rated and
E-rated emission factors are based on limited test data; these factors may not be representative
of the industry.
b References 12,14.
c Reference 15.
d References 8-9.
e References 7-9,11,15. Includes data from thermal catalytic oxidizers.
f Reference 16. EMISSION FACTOR RATING: E.
9.13.2-4
EMISSION FACTORS
9/95
-------
Table 9.13.2-2. EMISSION FACTORS FOR COFFEE ROASTING OPERATIONS"
EMISSION FACTOR RATING: D
Source
Batch roaster"
(SCC 3-02-002-20)
Batch roaster with
thermal oxidizer
(SCC 3-02-002-20)
Continuous roaster
(SCC 3-02-002-21)
Continuous roaster
with thermal
oxidizer
(SCC 3-02-002-21)
Decaffeination: solvent or
supercritical CO2 extraction
(SCC 3-02-002-10,-! 1)
Steam or hot air dryer
(SCC 3-02-002-16)
Spray drying
(SCC 3-02-003-01)
Freeze drying
(SCC 3-02-003-06)
vocb,
Ib/ton
0.86
0.047d
1.4f
0.16k
ND
ND
ND
ND
Methane,
Ib/ton
ND
ND
0.26g
0.15m
ND
ND
ND
ND
CO,
Ib/ton
ND
0.55d
1.5"
0.098k
ND
ND
ND
ND
C02!
Ib/ton
180
530e
120>
200"
ND
ND
ND
ND
" Emission factors are based on green coffee bean feed. Factors represent uncontrolled
emissions unless noted. SCC = Source Classification Code. ND = no data. D-rated and
E-rated emission factors are based on limited test data; these factors may not be representative
of the industry.
b Volatile organic compounds as methane. Measured using GC/FID.
c Reference 14.
d References 12-14.
e References 12,14.
f References 8-9,11,15.
g References 8-9,11,15. EMISSION FACTOR RATING: E.
h References 8-9,15.
j References 8-9,11,15. EMISSION FACTOR RATING: C.
k References 8-9,11,15. Includes data from thermal catalytic oxidizers.
m References 8-9,11,15. Includes data from thermal catalytic oxidizers. EMISSION FACTOR
RATING: E.
n References 9,11,15. Includes data from thermal catalytic oxidizers.
9/95
Food and Agricultural Products
9.13.2-5
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References For Section 9.13.2
1. M. N. Clifford and K. C. Willson, COFFEE-Botany, Biochemistry And Production Of Beans
And Beverage, The AVI Publishing Company, Inc., Westport, CT, 1985.
2. R. G. Ostendorf (ed.), "Coffee Processing", Air Pollution Engineering Manual, Van Nostrand
Reinhold, New York, NY, 1992.
3. J. M. L. Penninger, Supercritical Fluid Technology-Potential In The Fine Chemicals And
Pharmaceutical Industry, Presented at the Workshop on Prevention of Waste and Emissions in
the Fine Chemicals/Pharmaceutical Industry, Cork, Ireland, October 1993.
4. Telephone communication between B. Shrager, Midwest Research Institute, Gary, NC, and
M. Wood, Tetley's Corporation, Palisades Park, NJ, December 20, 1994.
5. R. J. Clarke and R. MacRae, editors, Coffee, Volume 2: Technology, Elsevier Science
Publishing Company, Inc., New York, NY, 1987.
6. G. Wasserman et al, "Coffee", Kirk-Othmer Encyclopedia Of Chemical Technology, 4th. Ed.,
Volume No. 6, John Wiley & Sons, Inc., 1992.
7. Source Test Report, Paniculate Emissions, Premium Coffee, Wall, New Jersey, Princeton
Testing Lab, Princeton, NJ, January 1987.
8. Compliance Stack Sampling Report For Hills Brothers Coffee, Inc., Edgewater, New Jersey,
Ambient Engineering, Inc., Parlin, NJ, September 23, 1988.
9. Stack Sampling Report For Hills Brothers Coffee, Inc., Edgewater, New Jersey, On Thermal
Oxidizer #22 Inlet/Outlet, Ambient Engineering, Inc., Parlin, NJ, October 5, 1988.
10. Compliance Stack Sampling Report For General Foods Corporation, Maxwell House Division,
Hoboken, New Jersey, On Thermal Oxidizer Met And Outlet, Recon Systems, Inc., Three
Bridges, NJ, March 13, 1989.
11. Nestle Foods Corporation Compliance Emission Testing Report, AirNova, Inc.,
Pennsauken, NJ, October 1990.
12. Source Test Report For Paniculate, Volatile Organic Compounds, And Carbon Monoxide
Emissions From The Coffee Roaster 7D Thermal Oxidizer At General Foods-Maxwell House
Division, Hoboken, New Jersey, Air Consulting and Engineering, Inc., Gainesville, FL,
December 20, 1990.
13. Source Test Repon For Volatile Organic Compounds And Carbon Monoxide Emissions From
The Coffee Roaster 7D Thermal Oxidizer At General Foods-Maxwell House Division,
Hoboken, New Jersey, Air Consulting and Engineering, Inc., Gainesville, FL, May 9, 1991.
14. Melitta USA, Inc., Blaw Knox Roaster Emission Compliance Test Program, AirNova, Inc,
Pennsauken, NJ, February 1992.
9.13.2-6 EMISSION FACTORS 9/95
-------
15. Nestle Beverage Co. Source Test Report, Coffee Roaster And Cooler, Best Environmental,
Inc., San Leandro, CA, October 1, 1992.
16. Summary Of Source Test Results, Bay Area Air Quality Management District, San Francisco,
CA, January 1991.
9/95 Food and Agricultural Products 9.13.2-7
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9.133 Snack Chip Deep Fat Frying
9.13.3.1 General1'3
The production of potato chips, tortilla chips, and other related snack foods is a growing,
competitive industry. Sales of such snack chips in the United States are projected to grow 5.7 percent
between 1991 and 1995. Between 1987 and 1991, potato chip sales increased from
649 x 106 kilograms (kg) to 712 x 106 kg (1,430 x 106 pounds [Ib] to 1,570 x 106 Ib), an increase of
63 x 106 kg (140 x 106 Ib) (10 percent). Snack chip plants are widely dispersed across the country,
with the highest concentrations in California and Texas.
New products and processes are being developed to create a more health-conscious image for
snack chips. Examples include the recent introduction of multigrain chips and the use of vegetable
oils (noncholesterol) hi frying. Health concerns are also encouraging the promotion and introduction
of nonfried snack products like pretzels, popcorn, and crackers.
9.13.3.2 Process Description1
Vegetables and other raw foods are cooked by industrial deep fat frying and are packaged for
later use by consumers. The batch frying process consists of immersing the food in the cooking oil
until it is cooked and then removing it from the oil. When the raw food is immersed in hot cooking
oil, the oil replaces the naturally occurring moisture in the food as it cooks. Batch and continuous
processes may be used for deep fat frying. In the continuous frying method, the food is moved
through the cooking oil on a conveyor. Potato chips are one example of a food prepared by deep fat
frying. Other examples include corn chips, tortilla corn chips, and multigrain chips.
Figure 9.13.3-1 provides general diagrams for the deep fat frying process for potato chips and
other snack chips. The differences between the potato chip process and other snack chip processing
operations are also shown. Some snack food processes (e. g., tortilla chips) include a toasting step.
Because the potato chip processes represent the largest industry segment, they are discussed here as a
representative example.
In the initial potato preparation, dirt, decayed potatoes, and other debris are first removed in
cleaning hoppers. The potatoes go next to washers, then to abrasion, steam, or lye peelers. Abrasion
is the most popular method. Preparation is either batch or continuous, depending on the number of
potatoes to be peeled.
The next step is slicing, which is performed by a rotary slicer. Potato slice widths will vary
with the condition of the potatoes and with the type of chips being made. The potato slices move
through rotating reels where high-pressure water separates the slices and removes starch from the cut
surfaces. The slices are then transferred to the rinse tank for final rinsing.
Next, the surface moisture is removed by 1 or more of the following methods: perforated
revolving drum, sponge rubber-covered squeeze roller, compressed air systems, vibrating mesh belt,
heated air, or centrifugal extraction.
The partially dried chips are then fried. Most producers use a continuous process, in which
the slices are automatically moved through the fryer on a mesh belt. Batch frying, which is used for
1/95 Food And Agricultural Industries 9.13.3-1
-------
POTATO CHIP
OTHER SNACK CHIPS
RAW MATERIAL PREPARATION
• Cleaning
• Slicing
• Starch removal
• Moisture reduction
RAW MATERIAL
PREPARATION
• Extruder
• Die/Cutter
NOX AND VOC
EMISSIONS TO ATMOSPHERE
t
GAS FIRED
TOASTER
(SCC 3-02-036-04)
PARTICULATE MATTER
AND VOC EMISSIONS
TO ATMOSPHERE
i
HOT OIL
DEEP FAT FRYING
(SCC 3-02-036-01)
(SCC 3-02-036-03)
HOT OIL
DEEP FAT FRYING
(SCC 3-02-036-02)
SEASONING
and
PACKAGING
SEASONING
and
PACKAGING
Figure 9.13.3-1. Generalized deep fat frying process for snack foods.
(Source Classification Codes in parentheses.)
9.13.3-2
EMISSION FACTORS
1/95
-------
a smaller quantity of chips, involves placing the chips hi a frying kettle for a period of tune and then
removing them. A variety of oils may be used for frying chips, with cottonseed, corn, and peanut
oils being the most popular. Canola and soybean oils also are used. Animal fats are rarely used in
this industry.
As indicated in Figure 9.13.3-1, the process for other snack chips is similar to that for potato
chip frying. Typically, the raw material is extruded and cut before entering the fryer. In some cases,
the chips may be toasted before frying.
9.13.3.2 Emissions And Controls2'3
Emissions -
Paniculate matter is the major air pollutant emitted from the deep fat frying process.
Emissions are released when moist foodstuff, such as potatoes, is introduced into hot oil. The rapid
vaporization of the moisture hi the foodstuff results in violent bubbling, and cooking oil droplets, and
possibly vapors, become entrained in the water vapor stream. The emissions are exhausted from the
cooking vat and into the ventilation system. Where emission controls are employed, condensed water
and oil droplets in the exhaust stream are collected by control devices before the exhaust is routed to
the atmosphere. The amount of paniculate matter emitted depends on process throughput, oil
temperature, moisture content of the feed material, equipment design, and stack emission controls.
Volatile organic compounds (VOC) are also produced in deep fat frying, but they are not a
significant percentage of total frying emissions because of the low vapor pressure of the vegetable oils
used. However, when the oil is entrained into the water vapor produced during frying, the oil may
break down into volatile products. Small amounts of VOC and combustion products may also be
emitted from toasters, but quantities are expected to be negligible.
Tables 9.13.3-1 and 9.13.3-2 provide uncontrolled and controlled paniculate matter emission
factors, in metric and English units, for snack chip frying. Table 9.13.3-3 provides VOC emission
factors, in metric and English units, for snack chip frying without controls. Emission factors are
calculated as the weight of paniculate matter or VOC per ton of finished product, including salt and
seasonings.
Controls -
Paniculate matter emission control equipment is typically installed on potato chip fryer
exhaust streams because of the elevated paniculate loadings caused by the high volume of water
contained hi potatoes. Examples of control devices are mist eliminators, impingement devices, and
wet scrubbers. One manufacturer has indicated that catalytic and thermal incinerators are not
practical because of the high moisture content of the exhaust stream.
1/95 Food And Agricultural Industries 9.13.3-3
-------
Table 9.13.3-1 (Metric Units). PARTICULATE MATTER EMISSION FACTORS FOR
SNACK CHIP DEEP FAT FRYING*
EMISSION FACTOR RATING: E (except as noted)
Process
Continuous deep fat fryer- potato
chipsb
(SCC 3-02-036-01)
Continuous deep fat fryer— other
snack chipsb
(SCC 3-02-036-42)
Continuous deep fat fryer with
standard mesh pad mist eliminator-
potato chips0
(SCC 3-02-036-01)
Continuous deep fat fryer with
high-efficiency mesh pad mist
eliminator— potato chips6
(SCC 3-02-036-01)
Continuous deep fat fryer with
standard mesh pad mist eliminator-
other snack chips*
(SCC 3-02-036-02)
Batch deep fat fryer with hood
scrubber— potato chips8
(SCC 3-02-036-03)
Filterable PM
PM
0.83
0.28
0.35d
0.12
0.1 ld
0.89d
PM-10
ND
ND
0.30
ND
0.088
ND
Condensable PM
Inorganic Organic J Total
ND ND 0.19
ND ND 0.12
0.0040d 0.19d 0.19
0.12 0.064 0.18
0.017 0.022 0.039
0.66d 0.17 0.83
Total
PM-10
ND
ND
0.49
ND
0.13
ND
a Factors are for uncontrolled emissions, except as noted. All emission factors in kg/Mg of chips
produced. SCC = Source Classification Code. ND = no data.
b Reference 3.
c References 6, 10-11. The standard mesh pad mist eliminator, upon which these emission factors
are based, includes a single, 6-inch, 2-layer mist pad that operates with a pressure drop of about
0.5-inch water column (when clean).
d EMISSION FACTOR RATING: D
e References 4-5. The high-efficiency mesh pad eliminator, upon which these emission factors are
based, includes a coarse-weave 4-inch mist pad and a 6-inch fine weave pad, and operates with a
2.5- to 3-inch water column pressure drop (when clean).
f References 6-7.
g References 8-9.
9.13.3-4
EMISSION FACTORS
1/95
-------
Table 9.13.3-2 (English Units). PARTICULATE MATTER EMISSION FACTORS FOR
SNACK CHIP DEEP FAT FRYING*
EMISSION FACTOR RATING: E (except as noted)
Process
Continuous deep fat fryer-potato
chipsb
(SCC 3-02-036-01)
Continuous deep fat fryer-other
snack chipsb
(SCC 3-02-036-02)
Continuous deep fat fryer with
standard mesh pad mist
eliminator-potato chips0
(SCC 3-02-036-01)
Continuous deep fat fryer with high-
efficiency mesh pad mist
eliminator— potato chips0
(SCC 3-02-036-01)
Continuous deep fat fryer with
standard mesh pad mist
eliminator-other snack chipsf
(SCC 3-02-036-02)
Batch deep fat fryer with hood
scrubber— potato chips8
(SCC 3-02-036-03)
Filterable PM
PM PM-10
1.6 ND
0.56 ND
O.TO41 0.60
0.24 ND
0.22d 0.18
1.8d ND
Condensable PM
Inorganic Organic Total
ND ND 0.39
ND ND 0.24
O.OOSO*1 0.37d 0.38
0.23 0.13 0.36
0.034 0.044 0.078
1.3d 0.33 1.6
Total
PM-10
ND
ND
0.98
ND
0.26
ND
a Factors are for uncontrolled emissions, except as noted. All emission factors in Ib/ton of chips
produced. SCC = Source Classification Code. ND = no data.
b Reference 3.
c References 6, 10-11. The standard mesh pad mist eliminator, upon which these emission factors
are based, includes a single, 6-inch, 2-layer mist pad that operates with a pressure drop of about
0.5 inch water column (when clean).
d EMISSION FACTOR RATING: D
e References 4-5. The high-efficiency mesh pad eliminator, upon which these emission factors are
based, includes a coarse-weave 4-inch mist pad and a 6-inch fine weave pad and operates with a
2.5- to 3-inch water column pressure drop (when clean).
f References 6-7.
g References 8-9.
1/95
Food And Agricultural Industries
9.13.3-5
-------
Table 9.13.3-3 (Metric Units). UNCONTROLLED VOC EMISSION FACTORS
FOR SNACK CHIP DEEP FAT FRYINGa'b
EMISSION FACTOR RATING: E
Process
Deep fat fryer— potato chips
(SCC 3-02-036-01)
Deep fat fryer— other snack chips
(SCC 3-02-036-02)
VOC
kg/Mg
0.0099
0.043
Ib/ton
0.020
0.085
a Reference 3. SCC = Source Classification Code.
b Expressed as equivalent weight of methane (CH^/unit weight of product.
References For Section 9.13.3
1. O. Smith, Potatoes: Production, Storing, Processing, Avi Publishing, Westport, CT, 1977.
2. Background Document For AP-42 Section 9.13.3, Snack Chip Deep Fat Frying, Midwest
Research Institute, Kansas City, MO, August 1994.
3. Characterization Of Industrial Deep Fat Fryer Air Emissions, Frito-Lay Inc., Piano, TX,
1991.
4. Emission Performance Testing For Two Fryer Lines, Western Environmental Services,
Redondo Beach, CA, November 19, 20, and 21, 1991.
5. Emission Performance Testing On One Continuous Fryer, Western Environmental Services,
Redondo Beach, CA, January 26, 1993.
6. Emission Performance Testing Of Two Fryer Lines, Western Environmental Services, Redondo
Beach, CA, November 1990.
7. Emission Performance Testing Of One Tortilla Continuous Frying Line, Western
Environmental Services, Redondo Beach, CA, October 20-21, 1992.
8. Emission Performance Testing Of Fryer No. 5, Western Environmental Services, Redondo
Beach, CA, February 4-5, 1992.
9. Emission Performance Testing Of Fryer No. 8, Western Environmental Services, Redondo
Beach, CA, February 3-4, 1992.
10. Emission Performance Testing Of Two Fryer Lines, Western Environmental Services, Redondo
Beach, CA, November 1989.
11. Emission Performance Testing Of Two Fryer Lines, Western Environmental Services, Redondo
Beach, CA, June 1989.
9.13.3-6
EMISSION FACTORS
1/95
-------
9.13.4 Yeast Production
9.13.4.1 General1
Baker's yeast is currently manufactured in the United States at 13 plants owned by 6 major
companies. Two main types of baker's yeast are produced, compressed (cream) yeast and dry yeast.
The total U. S. production of baker's yeast in 1989 was 223,500 megagrams (Mg) (245,000 tons).
Of the total production, approximately 85 percent of the yeast is compressed (cream) yeast, and the
remaining 15 percent is dry yeast. Compressed yeast is sold mainly to wholesale bakeries, and dry
yeast is sold mainly to consumers for home baking needs. Compressed and dry yeasts are produced
in a similar manner, but dry yeasts are developed from a different yeast strain and are dried after
processing. Two types of dry yeast are produced, active dry yeast (ADY) and instant dry yeast
(IDY). Instant dry yeast is produced from a faster-reacting yeast strain than that used for ADY. The
main difference between ADY and IDY is that ADY has to be dissolved in warm water before usage,
but IDY does not.
9.13.4.2 Process Description1
Figure 9.13.4-1 is a process flow diagram for the production of baker's yeast. The first stage
of yeast production consists of growing the yeast from the pure yeast culture in a series of
fermentation vessels. The yeast is recovered from the final fermentor by using centrifugal action to
concentrate the yeast solids. The yeast solids are subsequently filtered by a filter press or a rotary
vacuum filter to concentrate the yeast further. Next, the yeast filter cake is blended in mixers with
small amounts of water, emulsifiers, and cutting oils. After this, the mixed press cake is extruded
and cut. The yeast cakes are then either wrapped for shipment or dried to form dry yeast.
Raw Materials1"3 -
The principal raw materials used in producing baker's yeast are the pure yeast culture and
molasses. The yeast strain used in producing compressed yeast is Saccharomyces cerevisiae. Other
yeast strains are required to produce each of the 2 dry yeast products, ADY and IDY. Cane molasses
and beet molasses are the principal carbon sources to promote yeast growth. Molasses contains 45 to
55 weight percent fermentable sugars, in the forms of sucrose, glucose, and fructose.
The amount and type of cane and beet molasses used depend on the availability of the
molasses types, costs, and the presence of inhibitors and toxins. Usually, a blend consisting of both
cane and beet molasses is used in the fermentations. Once the molasses mixture is blended, the pH is
adjusted to between 4.5 and 5.0 because an alkaline mixture promotes bacteria growth. Bacteria
growth occurs under the same conditions as yeast growth, making pH monitoring very important.
The molasses mixture is clarified to remove any sludge and is then sterilized with high-pressure
steam. After sterilization, it is diluted with water and held in holding tanks until it is needed for the
fermentation process.
A variety of essential nutrients and vitamins is also required in yeast production. The nutrient
and mineral requirements include nitrogen, potassium, phosphate, magnesium, and calcium, with
traces of iron, zinc, copper, manganese, and molybdenum. Normally, nitrogen is supplied by adding
ammonium salts, aqueous ammonia, or anhydrous ammonia to the feedstock. Phosphates and
magnesium are added, in the form of phosphoric acid or phosphate salts and magnesium salts.
Vitamins are also required for yeast growth (biotin, inositol, pantothenic acid, and thiamine).
1/95 Food And Agricultural Industries 9.13.4-1
-------
RAW MATERIALS
VOC, CO2
FERMENTATION STAGES
Flask Fermentation (F1)
Pure Culture Fermentation (F2/F3)
Intermediate Fermentation (F4)
3-02-034-04
Stock Fermentation (F5)
3-02-034-05
Pitch Fermentation (F6)
3-02-034-06
Trade Fermentation (F7)
3-02-034-07
t
VOC
VOC
EXTRUSION AND CUTTING
SHIPMENT OF PACKAGED YEAST
Figure 9.13.4-1. Typical process flow diagram for the seven-stage production of baker's yeast, with
Source Classification Codes shown for compressed yeast. Use 3-02-035-XX for compressed yeast.
Thiamine is added to the feedstock. Most other vitamins and nutrients are already present in
sufficient amounts in the molasses malt.
Fermentation1"3 -
Yeast cells are grown in a series of fermentation vessels. Yeast fermentation vessels are
operated under aerobic conditions (free oxygen or excess air present) because under anaerobic
conditions (limited or no oxygen) the fermentable sugars are consumed in the formation of ethanol
and carbon dioxide, which results in low yeast yields.
9.13.4-2
EMISSION FACTORS
1/95
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The initial stage of yeast growth takes place in the laboratory. A portion of the pure yeast
culture is mixed with molasses malt in a sterilized flask, and the yeast is allowed to grow for
2 to 4 days. The entire contents of this flask are used to inoculate the first fermentor in the pure
culture stage. Pure culture fermentations are batch fermentations, where the yeast is allowed to grow
for 13 to 24 hours. Typically, 1 to 2 fermentors are used in this stage of the process. The pure
culture fermentations are basically a continuation of the flask fermentation, except that they have
provisions for sterile aeration and aseptic transfer to the next stage.
Following the pure culture fermentations, the yeast mixture is transferred to an intermediate
fermentor that is either batch or fed-batch. The next fermentation stage is a stock fermentation. The
contents from the intermediate fermentor are pumped into the stock fermentor, which is equipped for
incremental feeding with good aeration. This stage is called stock fermentation, because after
fermentation is complete, the yeast is separated from the bulk of the fermentor liquid by centrifuging,
which produces a stock, or pitch, of yeast for the next stage. The next stage, pitch fermentation, also
produces a stock, or pitch, of yeast. Aeration is vigorous, and molasses and other nutrients are fed
incrementally. The liquor from this fermentor is usually divided into several parts for pitching the
final trade fermentations (adding the yeast to start fermentation). Alternately, the yeast may be
separated by centrifuging and stored for several days before its use in the final trade fermentations.
The final trade fermentation has the highest degree of aeration, and molasses and other
nutrients are fed incrementally. Large air supplies are required during the final trade fermentations,
so these vessels are often started in a staggered fashion to reduce the size of the air compressors. The
duration of the final fermentation stages ranges from 11 to 15 hours. After all of the required
molasses has been fed into the fermentor, the liquid is aerated for an additional 0.5 to 1.5 hours to
permit further maturing of the yeast, making it more stable for refrigerated storage.
The amount of yeast growth in the main fermentation stages described above increases with
each stage. Yeast growth is typically 120 kilograms (270 pounds) in the intermediate fermentor,
420 kilograms (930 pounds) in the stock fermentor, 2,500 kilograms (5,500 pounds) in the pitch
fermentor, and 15,000 to 100,000 kilograms (33,000 to 220,000 pounds) in the trade fermentor.
The sequence of the main fermentation stages varies among manufacturers. About half of
existing yeast operations are 2-stage processes, and the remaining are 4-stage processes. When the
2-stage final fermentation series is used, the only fermentations following the pure culture stage are
the stock and trade fermentations. When the 4-stage fermentation series is used, the pure culture
stage is followed by intermediate, stock, pitch, and trade fermentations.
Harvesting And Packaging1"2 -
Once an optimum quantity of yeast has been grown, the yeast cells are recovered from the
final trade fermentor by centrifugal yeast separators. The centrifuged yeast solids are further
concentrated by a filter press or rotary vacuum filter. A filter press forms a filler cake containing
27 to 32 percent solids. A rotary vacuum filter forms cakes containing approximately 33 percent
solids. This filter cake is then blended in mixers with small amounts of water, emulsifiers, and
cutting oils to form the end product. The final packaging steps, as described below, vary depending
on the type of yeast product.
In compressed yeast production (SCC 3-02-035-XX), emulsifiers are added to give the yeast a
white, creamy appearance and to inhibit water spotting of the yeast cakes. A small amount of oil,
usually soybean or cottonseed oil, is added to help extrude the yeast through nozzles to form
continuous ribbons of yeast cake. The ribbons are cut, and the yeast cakes are wrapped and cooled to
below 8°C (46°F), at which time they are ready for shipment in refrigerated trucks.
1/95 Food And Agricultural Industries 9.13.4-3
>&
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In dry yeast production (SCC 3-02-034-XX), the product is sent to an extruder after filtration,
where emulsifiers and oils (different from those used for compressed yeast) are added to texturize the
yeast and to aid in extruding it. After the yeast is extruded in thin ribbons, it is cut and dried in
either a batch or a continuous drying system. Following drying, the yeast is vacuum packed or
packed under nitrogen gas before heat sealing. The shelf life of ADY and IDY at ambient
temperature is 1 to 2 years.
9.13.4.3 Emissions1'4-5
Volatile organic compound (VOC) emissions are generated as byproducts of the fermentation
process. The 2 major VOCs emitted are ethanol and acetaldehyde. Other byproducts consist of other
alcohols, such as butanol, isopropyl alcohol, 2,3-butanediol, organic acids, and acetates. Based on
emission test data, approximately 80 to 90 percent of total VOC emissions is ethanol, and the
remaining 10 to 20 percent consists of other alcohols and acetaldehyde. Acetaldehyde is a hazardous
air pollutant as defined under Section 112 of the Clean Air Act.
Volatile byproducts form as a result of either excess sugar (molasses) present in the fermentor
or an insufficient oxygen supply to it. Under these conditions, anaerobic fermentation occurs,
breaking down the excess sugar into alcohols and carbon dioxide. When anaerobic fermentation
occurs, 2 moles of ethanol and 2 moles of carbon dioxide are formed from 1 mole of glucose. Under
anaerobic conditions, the ethanol yield is increased, and yeast yields are decreased. Therefore, in
producing baker's yeast, it is essential to suppress ethanol formation in the final fermentation stages
by incremental feeding of the molasses mixture with sufficient oxygen to the fermentor.
The rate of ethanol formation is higher in the earlier stages (pure culture stages) than in the
final stages of the fermentation process. The earlier fermentation stages are batch fermentors, where
excess sugars are present and less aeration is used during the fermentation process. These
fermentations are not controlled to the degree that the final fermentations are controlled because the
majority of yeast growth occurs in the final fermentation stages. Therefore, there is no economical
reason for manufacturers to equip the earlier fermentation stages with process control equipment.
Another potential emission source at yeast manufacturing facilities is the system used to treat
process waste waters. If the facility does not use an anaerobic biological treatment system, significant
quantities of VOCs could be emitted from this stage of the process. For more information on
waste water treatment systems as an emission source of VOCs^ please refer to EPA's Control
Technology Center document on industrial waste water treatment systems, Industrial Wastewater
Volatile Organic Compound Emissions - Background Information For BACT/LAER, or see Section 4.3
of AP-42. At facilities manufacturing dry yeast, VOCs may also be emitted from the yeast dryers,
but no information is available on the relative quantity of VOC emissions from this source.
9.13.4.4 Controls6
Only 1 yeast manufacturing facility uses an add-on pollution control system to reduce VOC
emissions from the fermentation process. However, all yeast manufacturers suppress ethanol
formation through varying degrees of process control, such as incrementally feeding the molasses
mixture to the fermentors so that excess sugars are not present, or supplying sufficient oxygen to the
fermentors to optimize the dissolved oxygen content of the liquid in the fermentor. The adequacy of
oxygen distribution depends upon the proper design and operation of the aeration and mechanical
agitation systems of the fermentor. The distribution of oxygen by the air sparger system to the malt
mixture is critical. If oxygen is not being transferred uniformly throughout the malt, then ethanol
9.13.4-4 EMISSION FACTORS 1/95
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will be produced in the oxygen-deficient areas of the fermentor. The type and position of baffles
and/or a highly effective mechanical agitation system can ensure proper distribution of oxygen.
A more sophisticated form of process control involves using a continuous monitoring system
and feedback control. In such a system, process parameters are monitored, and the information is
sent to a computer. The computer is then used to calculate sugar consumption rates through material
balance techniques. Based on the calculated data, the computer continuously controls the addition of
molasses. This type of system is feasible, but it is difficult to design and implement. Such enhanced
process control measures can suppress ethanol formation from 75 to 95 percent.
The 1 facility with add-on control uses a wet scrubber followed by a biological filter.
Performance data from this unit suggest an emission control efficiency of better than 90 percent.
9.13.4.5 Emission Factors1'6"9
Table 9.13.4-1 provides emission factors for a typical yeast fermentation process with a
moderate degree of process control. The process emission factors in Table 9.13.4-1 were developed
from 4 test reports from 3 yeast manufacturing facilities. Separate emission factors are given for
intermediate, stock/pitch, and trade fermentations. The emission factors in Table 9.13.4-1 are
expressed in units of VOC emitted per fermentor per unit of yeast produced in that fermentor.
In order to use the emission factors for each fermentor, the amount of yeast produced in each
fermentor must be known. The following is an example calculation for a typical facility:
Fermentation
Stage
Intermediate
Stock
Pitch
Trade
TOTAL
Yeast Yield Per
Batch, Ib (A)
265
930
5,510
33,070
—
No. Of Batches
Processed Per
Year, #/yr (B)
156
208
208
1,040
—
Total Yeast
Production Per
Stage, tons/yr
(C = Ax
B/2,000)
21
97
573
17,196
—
Emission
Factor, Ib/ton
(D)
36
5
5
5
—
Emissions, Ib
(E = C x D)
756
485
2,865
85,980
90,086
Percent of Total
Emissions
0.84
0.54
3.18
95.44
100
In most cases, the annual yeast production per stage will not be available. However, a reasonable
estimate can be determined based on the emission factor for the trade fermentor and the total yeast
production for the facility. Trade fermentors produce the majority of all VOCs emitted from the
facility because of the number of batches processed per year and of the amount of yeast grown in
these fermentors. Based on emission test data and process data regarding the number of batches
processed per year, 80 to 90 percent of VOCs emitted from fermentation operations are a result of the
trade fermentors.
Using either a 2-stage or 4-stage fermentation process has no significant effect on the
overall emissions for the facility. Facilities that use the 2-stage process may have larger fermentors
or may produce more batches per year than facilities that use a 4-stage process. The main factors
affecting emissions are the total yeast production for a facility and the degree of process control used.
1/95
Food And Agricultural Industries
9.13.4-5
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Table 9.13.4-1 (Metric And English Units). VOLATILE ORGANIC COMPOUND (VOC)
EMISSION FACTORS FOR YEAST MANUFACTURING3
EMISSION FACTOR RATING: E
Emission Pointb
VOCC
VOC Emitted Per Stage Per
Amount Of Yeast Produced
In A Stage,
kg VOC/Mg Yeast
VOC Emitted Per Stage Per
Amount Of Yeast Produced
In A Stage,
Ib VOC/ton Yeast
Fermentation stages
Flask (Fl)
Pure culture (F2/F3)
Intermediate (F4)
(SCC 3-02-034-04)
Stock (F5)
(SCC 3-02-034-05)
Pitch (F6)
(SCC 3-02-034-06)
Trade (F7)
(SCC 3-02-034-07)
Waste treatment
(SCC 3-02-034-10)
Drying
(SCC 3-02-034-20)
ND
ND
18
2.5
2.5
2.5
ND
ND
36
5.0
5.0
5.0
See Section 4.3 of AP-42
ND
ND
a References 1,6-10. Total VOC as ethanol. SCC = Source Classification Code. ND = no data.
F numbers refer to fermentation stages (see Figure 9.13.4-1).
b Factors are for both dry yeast (SCC 3-02-034-XX) and compressed yeast (SCC 3-02-035-XX).
c Factors should be used only when plant-specific emission data are not available because of the high
degree of emissions variability among facilities and among batches within a facility.
d Some yeast manufacturing facilities use a 2-stage final fermentation process, and others use a
4-stage final fermentation process. Factors for each stage cannot be summed to determine an
overall emission factor for a facility, since they are based on yeast yields in each fermentor rather
than total yeast production. Total yeast production for a facility equals only the yeast yield from
the trade fermentations. Note that CO2 is also a byproduct of fermentation, but no data are
available on the amount emitted.
References For Section 9.13.4
1. Assessment Of VOC Emissions And Their Control From Baker's Yeast Manufacturing
Facilities, EPA-450/3-91-027, U. S. Environmental Protection Agency, Research Triangle
Park, NC, January 1992.
2. S. L. Chen and M. Chigar, "Production Of Baker's Yeast", Comprehensive Biotechnology,
Volume 20, Pergamon Press, New York, NY, 1985.
3. G. Reed and H. Peppier, Yeast Technology, Avi Publishing Company, Westport, CT, 1973.
9.13.4-6
EMISSION FACTORS
1/95
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4. H. Y. Wang, et al., "Computer Control Of Baker's Yeast Production", Biotechnology And
Bioengineering, Cambridge, MA, Volume 21, 1979.
5. Industrial Wastewater VOC Emissions - Background For BACT/LAER, EPA-450/3-90-004,
U. S. Environmental Protection Agency, Research Triangle Park, NC, March 1990.
6. Written communication from R. Jones, Midwest Research Institute, Gary, NC, to the project
file, April 28, 1993.
7. Fermentor Emissions Test Report, Gannet Fleming, Inc., Baltimore, MD, October 1990.
8. Final Test Report For Fermentor No. 5, Gannett Fleming, Inc., Baltimore, MD, August 1990.
9. Written communication from J. Leatherdale, Trace Technologies, Bridgewater, NJ, to J.
Hogan, Gist-brocades Food Ingredients, Inc., East Brunswick, NJ, April 7, 1989.
10. Fermentor Emissions Test Report, Universal Foods, Inc., Baltimore, MD, Universal Foods,
Inc., Milwaukee, WI, 1990.
1/95 Food And Agricultural Industries 9.13.4-7
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9.14 Tobacco Products
[Work In Progress]
1/95 Food And Agricultural Industries 9.14-1
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9.15 Leather Tanning
[Work In Progress]
1/95 Food And Agricultural Industries 9.15-1
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9.15 Leather Tanning
9.15.1 General1'4
Leather tanning is the process of converting raw hides or skins into leather. Hides and skins have the
ability to absorb tannic acid and other chemical substances that prevent them from decaying, make them
resistant to wetting, and keep them supple and durable. The surface of hides and skins contains the hair and
oil glands and is known as the grain side. The flesh side of the hide or skin is much thicker and softer. The
three types of hides and skins most often used in leather manufacture are from cattle, sheep, and pigs.
Tanning is essentially the reaction of collagen fibers in the hide with tannins, chromium, alum, or
other chemical agents. The most common tanning agents used in the U. S. are trivalent chromium and
vegetable tannins extracted from specific tree barks. Alum, syntans (man-made chemicals), formaldehyde,
glutaraldehyde, and heavy oils are other tanning agents.
There are approximately 111 leather tanning facilities in the United States. However, not every
facility may perform the entire tanning or finishing process. Leather tanning and finishing facilities are most
prevalent in the northeast and midwest states; Pennsylvania, Massachusetts, New York, and Wisconsin
account for almost half of the facilities. The number of tanneries in the United States has significantly
decreased in the last 40 years due to the development of synthetic substitutes for leather, increased leather
imports, and environmental regulation.
9.15.2 Process Description1 ~2-5-6
Although the title of this section is "Leather Tanning", the entire leathermaking process is considered
here, not just the actual tanning step. "Leather tanning" is a general term for the numerous processing steps
involved in converting animal hides or skins into finished leather. Production of leather by both vegetable
tanning and chrome tanning is described below. Chrome tanning accounts for approximately 90 percent of U.
S. tanning production. Figure 9.15-1 presents a general flow diagram for the leather tanning and finishing
process. Trimming, soaking, fleshing, and unhairing, the first steps of the process, are referred to as the
beamhouse operations. Bating, pickling, tanning, wringing, and splitting are referred to as tanyard processes.
Finishing processes include conditioning, staking, dry milling, buffing, spray finishing, and plating.
9.15.2.1 Vegetable Tanning -
Heavy leathers and sole leathers are produced by the vegetable tanning process, the oldest of any
process in use in the leather tanning industry. The hides are first trimmed and soaked to remove salt and
other solids and to restore moisture lost during curing. Following the soaking, the hides are fleshed to remove
the excess tissue, to impart uniform thickness, and to remove muscles or fat adhering to the hide. Hides are
then dehaired to ensure that the grain is clean and the hair follicles are free of hair roots. Liming is the most
common method of hair removal, but thermal, oxidative, and chemical methods also exist The normal
procedure for liming is to use a series of pits or drums containing lime liquors (calcium hydroxide) and
sharpening agents. Following liming, the hides are dehaired by scraping or by machine. Deliming is then
performed to make the skins receptive to the vegetable tanning. Bating, an enzymatic action for the removal
of unwanted hide components after liming, is performed to impart softness, stretch, and flexibility to the
leather. Bating and deliming are usually performed together by placing the hides in an aqueous solution of an
ammonium salt and proteolytic
6/97 Food And Agricultural Industry 9.15-1
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BEAMHOUSE
TANYARD
Chrome Tanning
RETAN, COLOR,
FATLIQUOR
FINISHING
Deceiving and Stonng Hides|
Trimming
Soaking and Washing
:::::::*"::::;:
Fleshing
---I---
Unhainng
Bating
_L
Pickling
Wringing/Siding
Spliting
Grain
portion!
Shaving
Retanning
Bleaching and Colonng
FatUquonng
(Chrome tanning)
±.
Setting Out
±.
Drying
Conditioning
Staking. Dry Milling
Buffing
Finishing and Plating
• Sulfides, NH3
Vegetable Tanning
Flesh portion
»• To split tannery, retanning
--*• PM
• Possible VOC
Possible VOC
». Possible PM, VOC, orNH 3
*• PM
*• VOC
9.15-2
Figure 9.15-1. General flow diagram for leather tanning and finishing process.
EMISSION FACTORS
6/97
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enzymes at 27° to 32°C (80° to 90°F). Pickling may also be performed by treating the hide with a brine
solution and sulfuric acid to adjust the acidity for preservation or tanning.
In the vegetable tanning process, the concentration of the tanning materials starts out low and is
gradually increased as the tannage proceeds. It usually takes 3 weeks for the tanning material to penetrate to
the center of the hide. The skins or hides are then wrung and may be cropped or split; heavy hides may be
retanned and scrubbed. For sole leather, the hides are commonly dipped in vats or drums containing sodium
bicarbonate or sulfuric acid for bleaching and removal of surface tannins. Materials such as lignosulfate,
com sugar, oils, and specialty chemicals may be added to the leather. The leather is then set out to smooth
and dry and may then undergo further finishing steps. However, a high percentage of vegetable-tanned
leathers do not undergo retanning, coloring, fatliquoring, or finishing.
Leather may be dried by any of five common methods. Air drying is the simplest method. The
leather is hung or placed on racks and dried by the natural circulation of air around it. A toggling unit
consists of a number of screens placed in a dryer that has controlled temperature and humidity. In a pasting
unit, leathers are pasted on large sheets of plate glass, porcelain, or metal and sent through a tunnel dryer with
several controlled temperature and humidity zones. In vacuum drying, the leather is spread out, grain down,
on a smooth surface to which heat is applied. A vacuum hood is placed over the surface, and a vacuum is
applied to aid in drying the leather. High-frequency drying involves the use of a high frequency
electromagnetic field to dry the leather.
9.15.2.2 Chrome Tanning-
Chrome-tanned leather tends to be softer and more pliable than vegetable-tanned leather, has higher
thermal stability, is very stable in water, and takes less time to produce than vegetable-tanned leather.
Almost all leather made from lighter-weight cattle hides and from the skin of sheep, lambs, goats, and pigs is
chrome tanned. The first steps of the process (soaking, fleshing, liming/dehairing, deliming, bating, and
pickling) and the drying/finishing steps are essentially the same as in vegetable tanning. However, in chrome
tanning, the additional processes of retanning, dyeing, and fatliquoring are usually performed to produce
usable leathers and a preliminary degreasing step may be necessary when using animal skins, such as
sheepskin.
Chrome tanning in the United States is performed using a one-bath process that is based on the
reaction between the hide and a trivalent chromium salt, usually a basic chromium sulfate. In the typical one-
bath process, the hides are in a pickled state at a pH of 3 or lower, the chrome tanning materials are
introduced, and the pH is raised. Following tanning, the chrome tanned leather is piled down, wrung, and
graded for the thickness and quality, split into flesh and grain layers, and shaved to the desired thickness. The
grain leathers from the shaving machine are then separated for retanning, dyeing, and fatliquoring. Leather
that is not subject to scuffs and scratches can be dyed on the surface only. For other types of leather (i. e.,
shoe leather) the dye must penetrate further into the leather. Typical dyestuffs are aniline-based compounds
that combine with the skin to form an insoluble compound.
Fatliquoring is the process of introducing oil into the skin before the leather is dried to replace the
natural oils lost in beamhouse and tanyard processes. Fatliquoring is usually performed in a drum using an
oil emulsion at temperatures of about 60° to 66°C (140° to 150°F) for 30 to 40 minutes. After fatliquoring,
the leather is wrung, set out, dried, and finished. The finishing process refers to all the steps that are carried
out after drying.
6/97 Food And Agricultural Industry 9.15-3
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9.15.2.3 Leather Finishing
Leathers may be finished in a variety of ways: buffed with fine abrasives to produce a suede finish;
waxed, shellacked, or treated with pigments, dyes, and resins to achieve a smooth, polished surface and the
desired color; or lacquered with urethane for a glossy patent leather. Water-based or solvent-based finishes
may also be applied to the leather. Plating is then used to smooth the surface of the coating materials and
bond them to the grain. Hides may also be embossed.
9.15.3 Emissions and Controls2-4-6
There are several potential sources of air emissions in the leather tanning and finishing industry.
Emissions of VOC may occur during finishing processes, if organic solvents are used, and during other
processes, such as fatliquoring and drying. If organic degreasing solvents are used during soaking in suede
leather manufacture, these VOC may also evaporate to the atmosphere. Many tanneries are implementing
water-based coatings to reduce VOC emissions. Control devices, such as thermal oxidizers, are used less
frequently to reduce VOC emissions. Ammonia emissions may occur during some of the wet processing
steps, such as deliming and unhairing, or during drying if ammonia is used to aid dye penetration during
coloring. Emissions of sulfides may occur during liming/unhairing and subsequent processes. Also, alkaline
sulfides in tannery wastewater can be converted to hydrogen sulfide if the pH is less than 8.0, resulting in
release of this gas. Particulate emissions may occur during shaving, drying, and buffing; they are controlled
by dust collectors or scrubbers.
Chromium emissions may occur from chromate reduction, handling of basic chromic sulfate powder,
and from the buffing process. No air emissions of chromium occur during soaking or drying. At plants that
purchase chromic sulfate in powder form, dust containing bivalent chromium may be emitted during storage,
handling, and mixing of the dry chromic sulfate. The buffing operation also releases particulates, which may
contain chromium. Leather tanning facilities, however, have not been viewed as sources of chromium
emissions by the States in which they are located.
References for Section 9.15
1. K. Bienkiewicz, Physical Chemistry Of Leathermaking, Krieger Publishing Co., Malabar, FL, 1983.
2. Development Document For Effluent Limitations Guidelines And Standards For The Leather
Tanning And Finishing Point Source Category, EPA-440/1-82-016, U. S. Environmental Protection
Agency, Research Triangle Park, NC, November, 1982.
3. 1992 Census Of Manufactures, U. S. Department of Commerce, Bureau of Census, Washington,
DC, April 1995.
4. Telecon, A. Marshall, Midwest Research Institute, with F. Rutland, Environmental Consultant,
Leather Industries of America, August 7,1996.
5. 1996 Membership Directory, Leather Industries of America Inc.
6. M. T. Roberts and D. Etherington, Bookbinding And The Conservation Of Books, A Dictionary Of
Descriptive Terminology.
7. T. C. Thorstensen, Practical Leather Technology, 4th Ed., Krieger Publishing Co., Malabar, FL,
1993.
9.15-4 EMISSION FACTORS 6/97
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Locating And Estimating Air Emissions From Sources Of Chromium, EPA-450/4-84-007g, U. S.
Environmental Protection Agency, Research Triangle Park, NC, July 1984.
6/97 Food And Agricultural Industry 9.15-5
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9.16 Agricultural Wind Erosion
[Work In Progress]
1/95 Food And Agricultural Industries 9.16-1
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10. WOOD PRODUCTS INDUSTRY
Wood processing in this industry involves the conversion of trees into useful consumer products
and/or building materials such as paper, charcoal, treated and untreated lumber, plywood, particle board,
wafer board, and medium density fiber board. During the conversion processes, the major pollutants of
concern are particulate, PM-10, and volatile organic compounds. There also may be speciated organic
compounds that may be toxic or hazardous.
1/95 Wood Products Industry 10.0-1
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10.0-2 EMISSION FACTORS 1/95
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10.1 Lumber
[Work In Progress]
1/95 Wood Products Industry 10.1-1
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10.2 Chemical Wood Pulping
10.2.1 General
Chemical wood pulping involves the extraction of cellulose from wood by dissolving the
lignin that binds the cellulose fibers together. The 4 processes principally used in chemical pulping
are kraft, sulfite, neutral sulfite semichemical (NSSC), and soda. The first 3 display the greatest
potential for causing ah- pollution. The kraft process alone accounts for over 80 percent of the
chemical pulp produced in the United States. The choice of pulping process is determined by the
desired product, by the wood species available, and by economic considerations.
10.2.2 Kraft Pulping
10.2.2.1 Process Description1 -
The kraft pulping process (see Figure 10.2-1) involves the digesting of wood chips at elevated
temperature and pressure in "white liquor", which is a water solution of sodium sulfide and sodium
hydroxide. The white liquor chemically dissolves the lignin that binds the cellulose fibers together.
There are 2 types of digester systems, batch and continuous. Most kraft pulping is done hi
batch digesters, although the more recent installations are of continuous digesters. In a batch
digester, when cooking is complete, the contents of the digester are transferred to an atmospheric tank
usually referred to as a blow tank. The entire contents of the blow tank are sent to pulp washers,
where the spent cooking liquor is separated from the pulp. The pulp then proceeds through various
stages of washing, and possibly bleaching, after which it is pressed and dried into the finished
product. The "blow" of the digester does not apply to continuous digester systems.
The balance of the kraft process is designed to recover the cooking chemicals and heat. Spent
cooking liquor and the pulp wash water are combined to form a weak black liquor which is
concentrated hi a multiple-effect evaporator system to about 55 percent solids. The black liquor is
then further concentrated to 65 percent solids in a direct-contact evaporator, by bringing the liquor
into contact with the flue gases from the recovery furnace, or hi an indirect-contact concentrator. The
strong black liquor is then fired hi a recovery furnace. Combustion of the organics dissolved hi the
black liquor provides heat for generating process steam and for converting sodium sulfate to sodium
sulfide. Inorganic chemicals present hi the black liquor collect as a molten smelt at the bottom of the
furnace.
The smelt is dissolved hi water to form green liquor, which is transferred to a causticizing
tank where quicklime (calcium oxide) is added to convert the solution back to white liquor for return
to the digester system. A lime mud precipitates from the causticizing tank, after which it is calcined
hi a lime kiln to regenerate quicklime.
For process heating, for driving equipment, for providing electric power, etc., many mills
need more steam than can be provided by the recovery furnace alone. Thus, conventional industrial
boilers that burn coal, oil, natural gas, or bark and wood are commonly used.
9/90 (Reformatted 1/95) Wood Products Industry 10.2-1
-------
01
s
s
o.
I
a,
.1
o
T-N
10.2-2
EMISSION FACTORS
(Reformatted 1/95) 9/90
-------
10.2.2.2 Emissions And Controls1"7 -
Paniculate emissions from the kraft process occur largely from the recovery furnace, the lime
kiln and the smelt dissolving tank. These emissions are mainly sodium salts, with some calcium salts
from the lime kiln. They are caused mostly by carryover of solids and sublimation and condensation
of the inorganic chemicals.
Paniculate control is provided on recovery furnaces hi a variety of ways. In mills with either
cyclonic scrubber or cascade evaporator as the direct-contact evaporator, further control is necessary,
as these devices are generally only 20 to 50 percent efficient for particulates. Most often in these
cases, an electrostatic precipitator (ESP) is employed after the direct-contact evaporator, for an overall
paniculate control efficiency of from 85 to more than 99 percent. Auxiliary scrubbers may be added
at existing mills after a precipitator or a venturi scrubber to supplement older and less efficient
primary paniculate control devices.
Paniculate control on lime kilns is generally accomplished by scrubbers. Electrostatic
precipitators have been used in a few mills. Smelt dissolving tanks usually are controlled by mesh
pads, but scrubbers can provide further control.
The characteristic odor of the kraft mill is caused by the emission of reduced sulfur
compounds, the most common of which are hydrogen sulfide, methyl mercaptan, dimethyl sulfide,
and dimethyl disulfide, all with extremely low odor thresholds. The major source of hydrogen sulfide
is the direct contact evaporator, hi which the sodium sulfide in the black liquor reacts with the carbon
dioxide hi the furnace exhaust. Indirect contact evaporators can significantly reduce the emission of
hydrogen sulfide. The lime kiln can also be a potential source of odor, as a similar reaction occurs
with residual sodium sulfide hi the lime mud. Lesser amounts of hydrogen sulfide are emitted with
the noncondensables of offgases from the digesters and multiple-effect evaporators.
Methyl mercaptan and dimethyl sulfide are formed in reactions with the wood component,
lignin. Dimethyl disulfide is formed through the oxidation of mercaptan groups derived from the
lignin. These compounds are emitted from many points within a mill, but the main sources are the
digester/blow tank systems and the direct contact evaporator.
Although odor control devices, per se, are not generally found hi kraft mills, emitted sulfur
compounds can be reduced by process modifications and improved operating conditions. For
example, black liquor oxidation systems, which oxidize sulfides into less reactive thiosulfates, can
considerably reduce odorous sulfur emissions from the direct contact evaporator, although the vent
gases from such systems become minor odor sources themselves. Also, noncondensable odorous
gases vented from the digester/blow tank system and multiple effect evaporators can be destroyed by
thermal oxidation, usually by passing them through the lime kiln. Efficient operation of the recovery
furnace, by avoiding overloading and by maintaining sufficient oxygen, residence time, and
turbulence, significantly reduces emissions of reduced sulfur compounds from this source as well.
The use of fresh water instead of contaminated condensates in the scrubbers and pulp washers further
reduces odorous emissions.
Several new mills have incorporated recovery systems that eliminate the conventional direct-
contact evaporators. In one system, heated combustion ah", rather than fuel gas, provides direct-
contact evaporation. In another, the multiple-effect evaporator system is extended to replace the
direct-contact evaporator altogether. In both systems, sulfur emissions from the recovery
furnace/direct-contact evaporator can be reduced by more than 99 percent.
9/90 (Reformatted 1/95) Wood Products Industry 10.2-3
-------
Sulfur dioxide is emitted mainly from oxidation of reduced sulfur compounds in the recovery
furnace. It is reported that the direct contact evaporator absorbs about 75 percent of these emissions,
and further scrubbing can provide additional control.
Potential sources of carbon monoxide emissions from the kraft process include the recovery
furnace and lime kilns. The major cause of carbon monoxide emissions is furnace operation well
above rated capacity, making it impossible to maintain oxidizing conditions.
Some nitrogen oxides also are emitted from the recovery furnace and lime kilns, although
amounts are relatively small. Indications are that nitrogen oxide emissions are on the order of 0.5 to
1.0 kilograms per air-dried megagram (kg/Mg) (1 to 2 pounds per air-dried ton pb/ton]) of pulp
produced from the lime kiln and recovery furnace, respectively.5"6
A major source of emissions in a kraft mill is the boiler for generating auxiliary steam and
power. The fuels are coal, oil, natural gas, or bark/wood waste. See Chapter 1, "External
Combustion Sources", for emission factors for boilers.
Table 10.2-1 presents emission factors for a conventional kraft mill. The most widely used
paniculate control devices are shown, along with the odor reductions through black liquor oxidation
and incineration of noncondensable offgases. Tables 10.2-2, 10.2-3, 10.2-4, 10.2-5, 10.2-6, and
10.2-7 present cumulative size distribution data and size-specific emission factors for paniculate
emissions from sources within a conventional kraft mill. Uncontrolled and controlled size-specific
emission factors7 are presented in Figure 10.2-2, Figure 10.2-3, Figure 10.2-4, Figure 10.2-5,
Figure 10.2-6, and Figure 10.2-7. The particle sizes are expressed in terms of the aerodynamic
diameter in micrometers (pm).
10.2.3 Acid Sulfite Pulping
10.2.3.1 Process Description -
The production of acid sulfite pulp proceeds similarly to kraft pulping, except that different
chemicals are used hi the cooking liquor. In place of the caustic solution used to dissolve the lignin
in the wood, sulfurous acid is employed. To buffer the cooking solution, a bisulfite of sodium,
magnesium, calcium, or ammonium is used. A diagram of a typical magnesium-base process is
shown in Figure 10.2-8.
Digestion is carried out under high pressure and high temperature, in either batch mode or
continuous digesters, and in the presence of a sulfurous acid/bisulfite cooking liquid. When cooking
is completed, either the digester is discharged at high pressure into a blow pit, or its contents are
pumped into a dump tank at lower pressure. The spent sulfite liquor (also called red liquor) then
drains through the bottom of the tank and is treated and discarded, incinerated, or sent to a plant for
recovery of heat and chemicals. The pulp is then washed and processed through screens and
centrifuges to remove knots, bundles of fibers, and other material. It subsequently may be bleached,
pressed, and dried in papermaking operations.
Because of the variety of cooking liquor bases used, numerous schemes have evolved for heat
and/or chemical recovery. In calcium base systems, found mostly in older mills, chemical recovery is
not practical, and the spent liquor is usually discharged Or incinerated. In ammonium base
operations, heat can be recovered by combusting the spent liquor, but the ammonium base is thereby
consumed. In sodium or magnesium base operations, the heat, sulfur, and base all may be feasibly
recovered.
EMISSION FACTORS (Reformatted 1/95) 9/90
-------
•s
H
i
KJ Qi
2 O
i y
x-^ CJU
.S 'z.
D 2
J5 V5
I §
"H
to
g?r
Oi "-'
1
•8
S
M»_
•o
X
o
TO
o
e
Jo
* U
c ^
o
•e
S
°
U
•a
3^
1^
3
u
03
"3
o
tt
ctf
C
J
60
!
e
£
60
I
60
2
•a
M
c
o
£
00
1
e
2
U)
S
"So
0 "S
goj
O
3
0
ts
VO
d
S
d
d
Q
Z
Q
Z
Q
Z
a
z
a
z
a
Untreatedb
£
J3
.O
"g
«
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'"§
0 "^
d
d
S
d
o
d
Q
Z
Q
Z
Q
Z
Q
Z
Q
Z
Q
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Untreatedb
0
_c
V3
C3
^
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2
Cfl
I
03
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^3 C*^ CO f*} C*V
go o o o
in >n >n in
- - - - -
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Q
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Q in in in
Z in in in
Q
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^ in >n in
cn en m
M
Q o oo r< .2
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fr>
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o u
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Ui
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§ § .
Noncontact
without di
evaporate
Q
Z
0
J3
d
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d
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V)
in
Q
Z
Q
Z
(N
— '
Q.
U
odd
odd
R
odd
odd
Q Q Q
Z Z Z
Q Q Q
Z Z Z
«1 « Q
o o Z
_ _ Q
do*
ts
r- — i d
vri m -*
C*l O O
Untreated
Mesh pad
Scrubber
c
3
ao
•>
8
.a
T3
1
to
g
-------
cs
o
T-H
. ^
SC 2 is'Ea
fi
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10.2-6
._ S c
EMISSION FACTORS
(Reformatted 1/95) 9/90
-------
Table 10.2-2 (Metric Units). CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS FOR A RECOVERY BOILER WITH A
DIRECT-CONTACT EVAPORATOR AND AN ESP*
EMISSION FACTOR RATING: C
Paniculate Size
Gim)
15
10
6
2.5
1.25
1.00
0.625
Total
Cumulative Mass % <,
Stated Size
Uncontrolled
95.0
93.5
92.2
83.5
56.5
45.3
26.5
100
Controlled
ND
ND
68.2
53.8
40.5
34.2
22.2
100
Cumulative Emission Factor
(kg/Mg of Air-Dried Pulp)
Uncontrolled
86
84
83
75
51
41
24
90
Controlled
ND
ND
0.7
0.5
0.4
0.3
0.2
1.0
Reference 7. ND = no data.
100
90
SO
i-s 70
:|
:- SO
ff
Si jo
20
10
Uncontrolled
Controlled
l l I l i t 111
A 1 111 II
0.1
1.0
Partlclt dlMMter
10
1.0
.9
Ho.a
0.6
2»
*i
§1
0.4 .r
23
0.3 |^
0.2
0.1
0
100
Figure 10.2-2. Cumulative particle size distribution and size-specific emission
factors for recovery boiler with direct-contact evaporator and ESP.
9/90 (Reformatted 1/95)
Wood Products Industry
10.2-7
-------
Table 10.2-3 (Metric Units). CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS FOR A RECOVERY BOILER WITHOUT A
DIRECT-CONTACT EVAPORATOR BUT WITH AN ESP*
EMISSION FACTOR RATING: C
Paniculate Size
Gtm)
15
10
6
2.5
1.25
1.00
0.625
Total
Cumulative Mass % <•
Stated Size
Uncontrolled
ND
ND
ND
78.0
40.0
30.0
17.0
100
Controlled
78.8
74.8
71.9
67.3
51.3
42.4
29.6
100
Cumulative Emission Factor
(kg/Mg of Air-Dried Pulp)
Uncontrolled
ND
ND
ND
90
46
35
20
115
Controlled
0.8
0.7
0.7
0.6
0.5
0.5
0.3
1.0
"Reference 7. ND = no data.
ISO
s-s
Si
Controlled
Uncontrolled
0
0.1
' i i I I Mil
I I I I I III!
I I I I I III
1.0
0.9
o.g
" II
0.6 gS
«£
0.5 i
"'
0.3
0.2
0.1
1.0
10
100
Particle diameter
Figure 10.2-3. Cumulative particle size distribution and size-specific emission factors for
recovery boiler without direct-contact evaporator but with ESP.
10.2-8
EMISSION FACTORS
(Reformatted 1/95) 9/90
-------
Table 10.2-4 (Metric Units). CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS FOR A LIME KILN WITH A VENTURI SCRUBBER*
EMISSION FACTOR RATING: C
Paniculate Size
0*m)
15
10
6
2.5
1.25
1.00
0.625
Total
Cumulative Mass % <.
Stated Size
Uncontrolled
27.7
16.8
13.4
10.5
8.2
7.1
3.9
100
Controlled
98.9
98.3
98.2
96.0
85.0
78.9
54.3
100
Cumulative Emission Factor
(kg/Mg of Air-Dried Pulp)
Uncontrolled
7.8
4.7
3.8
2.9
2.3
2.0
1.1
28.0
Controlled
0.24
0.24
0.24
0.24
0.21
0.20
0.14
0.25
aReference 7.
30
Zl
5
Cm trailed
Uncontrolled
I 1 I
I I III
I I I I 11
0.1
1.0 10
Particle dtuwtir (in)
0.3
si
100
Figure 10.2-4. Cumulative particle size distribution and size-specific emission factors for
lime kiln with venturi scrubber.
9/90 (Reformatted 1/95)
Wood Products Industry
10.2-9
-------
Table 10.2-5 (Metric Units). CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS FOR A LIME KILN WITH AN ESP*
EMISSION FACTOR RATING: C
Paniculate Size
Otm)
15
10
6
2.5
1.25
1.00
0.625
Total
Cumulative Mass % <
Stated Size
Uncontrolled
27.7
16.8
13.4
10.5
8.2
7.1
3.9
100
Controlled
91.2
88.5
86.5
83.0
70.2
62.9
46.9
100
Cumulative Emission Factor
(kg/Mg of Air-Dried Pulp)
Uncontrolled
7.8
4.7
3.8
2.9
2.3
2.0
1.1
28.0
Controlled
0.23
0.22
0.22
0.21
0.18
0.16
0.12
0.25
Reference 7.
30
l,
ControilM
Uncontrolled
i i i i r 11 Q
0.3
0.2
0.1
0.1
1.0
10
100
Pwtlcli
Figure 10.2-5. Cumulative particle size distribution and size-specific emission factors for
lime kiln with ESP.
10.2-10
EMISSION FACTORS
(Reformatted 1/95) 9/90
-------
Table 10.2-6 (Metric Units). CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS FOR A SMELT DISSOLVING TANK WITH A
PACKED TOWER*
EMISSION FACTOR RATING: C
Paniculate Size
(tan)
15
10
6
2.5
1.25
1.00
0.625
Total
Cumulative Mass % <
Stated Size
Uncontrolled
90.0
88.5
87.0
73.0
47.5
40.0
25.5
100
Controlled
95.3
95.3
94.3
85.2
63.8
54.2
34.2
100
Cumulative Emission Factor
(kg/Mg of Air-Dried Pulp)
Uncontrolled
3.2
3.1
3.0
2.6
1.7
1.4
0.9
3.5
Controlled
0.48
0.48
0.47
0.43
0.32
0.27
0.17
0.50
"Reference 7.
o_
-.£•
5i *
?
li 3
J O
Controll
0.6
O.S
0.4
Uncontrolled
' • ' i i mi
1 - 1 I I I I II I - 1 - 1 I ' I I I I
Si
0.3 ii
0-2 i2
0.1
0.1
1.0 10
Pirtlclt dluetcr (in)
100
Figure 10.2-6. Cumulative particle size distribution and size-specific emission factors for
smelt dissolving tank with packed tower.
9/90 (Reformatted 1/95)
Wood Products Industry
10.2-11
-------
Table 10.2-7 (Metric Units). CUMULATIVE PARTICLE SIZE DISTRIBUTION AND
SIZE-SPECIFIC EMISSION FACTORS FOR A SMELT DISSOLVING TANK WITH A
VENTURI SCRUBBER*
EMISSION FACTOR RATING: C
Particulate Size
G*m)
15
10
6
2.5
1.25
1.00
0.625
Total
Cumulative Mass % <,
Stated Size
Uncontrolled
90.0
88.5
87.0
73.0
47.5
40.0
25.5
100
Controlled
89.9
89.5
88.4
81.3
63.5
54.7
38.7
100
Cumulative Emission Factor
(kg/Mg of Air-Dried Pulp)
Uncontrolled
3.2
3.1
3.0
2.6
1.7
1.4
0.9
3.5
Controlled
0.09
0.09
0.09
0.08
0.06
0.06
0.04
0.09
Reference 7.
If
l
0.1
CMtrol ltd
Uncontrolled
i.o
ao
1.0
0.9
0.8
0.7
100
0.4 £«
0-3 j!
0.2
0.1
0
Ptrtlclt dlMw
Figure 10.2-7. Cumulative particle size distribution and size-specific emission factors for
smelt dissolving tank with venturi scrubber.
10.2-12
EMISSION FACTORS
(Reformatted 1/95) 9/90
-------
f
1
•a
CJ
1
•S
bO
,
2
a.
1
I
2
o
53
S
CM
•8
«
op
(S
o
-------
If recovery is practiced, the spent (weak) red liquor (which contains more than half of the raw
materials as dissolved organic solids) is concentrated in a multiple-effect evaporator and a direct-
contact evaporator to 55 to 60 percent solids. This strong liquor is sprayed into a furnace and
burned, producing steam to operate the digesters, evaporators, etc. and to meet other power
requirements.
When magnesium base liquor is burned, a flue gas is produced from which magnesium oxide
is recovered in a multiple cyclone as fine white power. The magnesium oxide is then water slaked
and is used as circulating liquor in a series of venturi scrubbers, which are designed to absorb sulfur
dioxide from the flue gas and to form a bisulfite solution for use in the cook cycle. When sodium
base liquor is burned, the inorganic compounds are recovered as a molten smelt containing sodium
sulfide and sodium carbonate. This smelt may be processed further and used to absorb sulfur dioxide
from the flue gas and sulfur burner. In some sodium base mills, however, the smelt may be sold to a
nearby kraft mill as raw material for producing green liquor.
If liquor recovery is not practiced, an acid plant is necessary of sufficient capacity to fulfill
the mill's total sulfite requirement. Normally, sulfur is burned hi a rotary or spray burner. The gas
produced is then cooled by heat exchangers and a water spray and is then absorbed in a variety of
different scrubbers containing either limestone or a solution of the base chemical. Where recovery is
practiced, fortification is accomplished similarly, although a much smaller amount of sulfur dioxide
must be produced to make up for that lost in the process.
10.2.3.2 Emissions And Controls11 -
Sulfur dioxide (SO^ is generally considered the major pollutant of concern from sulfite pulp
mills. The characteristic "kraft" odor is not emitted because volatile reduced sulfur compounds are
not products of the lignin/bisulfite reaction.
A major SO2 source is the digester and blow pit (dump tank) system. Sulfur dioxide is
present hi the intermittent digester relief gases, as well as hi the gases given off at the end of the cook
when the digester contents are discharged into the blow pit. The quantity of sulfur dioxide evolved
and emitted to the atmosphere hi these gas streams depends on the pH of the cooking liquor, the
pressure at which the digester contents are discharged, and the effectiveness of the absorption systems
employed for SO2 recovery. Scrubbers can be installed that reduce SO2 from this source by as much
as 99 percent.
Another source of sulfur dioxide emissions is the recovery system. Since magnesium,
sodium, and ammonium base recovery systems all use absorption systems to recover SO2 generated hi
recovery furnaces, acid fortification towers, multiple effect evaporators, etc., the magnitude of SO2
emissions depends on the desired efficiency of these systems. Generally, such absorption systems
recover better than 95 percent of the sulfur so it can be reused.
The various pulp washing, screening, and cleaning operations are also potential sources of
SO2. These operations are numerous and may account for a significant fraction of a mill's SO2
emissions if not controlled.
The only significant paniculate source hi the pulping and recovery process is the absorption
system handling the recovery furnace exhaust. Ammonium base systems generate less particulate than
do magnesium or sodium base systems. The combustion productions are mostly nitrogen, water
vapor, and sulfur dioxide.
10.2-14 EMISSION FACTORS (Reformatted 1/95) 9/90
-------
Auxiliary power boilers also produce emissions in the sulfite pulp mill, and emission factors
for these boilers are presented hi Chapter 1, "External Combustion Sources". Table 10.2-8 contains
emission factors for the various sulfite pulping operations.
10.2.4 Neutral Sulfite Semichemical (NSSC) Pulping
10.2.4.1 Process Description9-12'14 -
In this method, wood chips are cooked hi a neutral solution of sodium sulfite and sodium
carbonate. Sulfite ions react with the lignin in wood, and the sodium bicarbonate acts as a buffer to
maintain a neutral solution. The major difference between all semichemical techniques and those of
kraft and acid sulfite processes is that only a portion of the lignin is removed during the cook, after
which the pulp is further reduced by mechanical disintegration. This method achieves yields as high
as 60 to 80 percent, as opposed to 50 to 55 percent for other chemical processes.
The NSSC process varies from mill to mill. Some mills dispose of their spent liquor, some
mills recover the cooking chemicals, and some, when operated in conjunction with kraft mills, mix
then: spent liquor with the kraft liquor as a source of makeup chemicals. When recovery is practiced,
the involved steps parallel those of the sulfite process.
10.2.4.2 Emissions And Controls9-12'14 -
Paniculate emissions are a potential problem only when recovery systems are involved. Mills
that do practice recovery but are not operated in conjunction with kraft operations often utilize
fluidized bed reactors to burn then: spent liquor. Because the flue gas contains sodium sulfate and
sodium carbonate dust, efficient particulate collection may be included for chemical recovery.
A potential gaseous pollutant is sulfur dioxide. Absorbing towers, digester/blower tank
systems, and recovery furnaces are the mam sources of SO2, with amounts emitted dependent upon
the capability of the scrubbing devices installed for control and recovery.
Hydrogen sulfide can also be emitted from NSSC mills which use kraft type recovery
furnaces. The mam potential source is the absorbing tower, where a significant quantity of hydrogen
sulfite is liberated as the cooking liquor is made. Other possible sources, depending on the operating
conditions, include the recovery furnace, and in mills where some green liquor is used hi the cooking
process, the digester/blow tank system. Where green liquor is used, it is also possible that significant
quantities of mercaptans will be produced. Hydrogen sulfide emissions can be eliminated if burned to
sulfur dioxide before the absorbing system.
Because the NSSC process differs greatly from mill to mill, and because of the scarcity of
adequate data, no emission factors are presented for this process.
9/90 (Reformatted 1/95) Wood Products Industry 10.2-15
-------
g
5
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9/90 (Refoimatted 1/95)
Wood Products Industry
10.2-17
-------
References For Section 10.2
1. Review Of New Source Performance Standards For Kraft Pulp Mills, EPA^50/3-83-017,
U. S. Environmental Protection Agency, Research Triangle Park, NC, September 1983.
2. Standards Support And Environmental Impact Statement, Volume I: Proposed Standards Of
Performance For Kraft Pulp Mills, EPA-450/2-76-014a, U. S. Environmental Protection
Agency, Research Triangle Park, NC, September 1976.
3. Kraft Pulping - Control Of TRS Emissions From Existing Mills, EPA-450/78-003b,
U. S. Environmental Protection Agency, Research Triangle Park, NC, March 1979.
4. Environmental Pollution Control, Pulp And Paper Industry, Pan I: Air, EPA-625/7-76-001,
U. S. Environmental Protection Agency, Washington, DC, October 1976.
5. A Study Of Nitrogen Oxides Emissions From Lime Kilns, Technical Bulletin Number 107,
National Council of the Paper Industry for Air and Stream Improvement, New York, NY,
April 1980.
6. A Study Of Nitrogen Oxides Emissions From Large Kraft Recovery Furnaces, Technical
Bulletin Number 111, National Council of the Paper Industry for Air and Stream
Improvement, New York, NY, January 1981.
7. Source Category Report For The Kraft Pulp Industry, EPA Contract Number 68-02-3156,
Acurex Corporation, Mountain View, CA, January 1983.
8. Source test data, Office Of Air Quality Planning And Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC, 1972.
9. 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.
10. Carbon Monoxide Emissions From Selected Combustion Sources Based On Short-Term
Monitoring Records, Technical Bulletin Number 416, National Council of the Paper Industry
for Air and Stream Improvement, New York, NY, January 1984.
11. Background Document: Acid Sulfite Pulping, EPA-450/3-77-005, U. S. Environmental
Protection Agency, Research Triangle Park, NC, January 1977.
12. E. R. Hendrickson, et al., Control Of Atmospheric Emissions In The Wood Pulping Industry,
Volume I, HEW Contract Number CPA-22-69-18, U.S. Environmental Protection Agency,
Washington, DC, March 15, 1970.
13. M. Benjamin, et al., "A General Description of Commercial Wood Pulping And Bleaching
Processes", Journal Of The Ah- Pollution Control Association, 19(3): 155-161, March 1969.
14. S. F. Caleano and B. M. Dillard, "Process Modifications For Air Pollution Control In Neutral
Sulfite Semi-chemical Mills", Journal Of The Air Pollution Control Association,
22(3): 195-199, March 1972.
10.2-18 EMISSION FACTORS (Reformatted 1/95) 9/90
-------
103 Pulp Bleaching
[Work In Progress]
1/95 Wood Products Industry 10.3-1
-------
10.4 Paper-making
[Work In Progress]
1/95 Wood Products Industry 10.4-1
-------
10.5 Plywood
[Work In Progress]
1/95 Wood Products Industry 10.5-1
-------
10.6 Reconstituted Wood Products
10.6.1 Waferboard And Oriented Strand Board
10.6.2 Particleboard
10.6.3 Medium Density Fiberboard
1/95 Wood Products Industry 10.6-1
-------
10.6.1 Waferboard And Oriented Strand Board
[Work In Progress]
1/95 Wood Products Industry 10.6.1-1
-------
10.6.2 Particleboard
[Work In Progress]
1/95 Wood Products Industry 10.6.2-1
-------
10.6.3 Medium Density Fiberboard
[Work In Progess]
1/95 Wood Products Industry 10.6.3-1
-------
10.7 Charcoal
10.7.1 Process Description1"4
Charcoal is the solid carbon residue following the pyrolysis (carbonization or destructive
distillation) of carbonaceous raw materials. Principal raw materials are medium to dense hardwoods
such as beech, birch, hard maple, hickory, and oak. Others are softwoods (primarily long leaf and
slash pine), nutshells, fruit pits, coal, vegetable wastes, and paper mill residues. Charcoal is used
primarily as a fuel for outdoor cooking. In some instances, its manufacture may be considered as a
solid waste disposal technique. Many raw materials for charcoal manufacture are wastes, as noted.
Charcoal manufacture is also used in forest management for disposal of refuse.
Recovery of acetic acid and methanol byproducts was initially responsible for stimulating the
charcoal industry. As synthetic production of these chemicals became commercialized, recovery of
acetic acid and methanol became uneconomical.
Charcoal manufacturing kilns generally can be classified as either batch or continuous multiple
hearth kilns; continuous multiple hearth kilns are more commonly used than are batch kilns. Batch
units such as the Missouri-type charcoal kiln (Figure 10.7-1) are small manually-loaded and -unloaded
kilns producing typically 16 megagrams (Mg) (17.6 tons) of charcoal during a 3-week cycle.
Continuous units (Figure 10.7-2) produce an average of 2.5 Mg per hour (Mg/hr) (2.75 tons per hour
[tons/hr]) of charcoal. During the manufacturing process, the wood is heated, driving off water and
highly volatile organic compounds (VOC). Wood temperature rises to approximately 275°C (527°F),
and the VOC distillate yield increases. At this point, external application of heat is no longer
required because the carbonization reactions become exothermic. At 350°C (662°F), exothermic
pyrolysis ends, and heat is again applied to remove the less volatile tarry materials from the product
charcoal.
Fabrication of briquettes from raw material may be either an integral part of a charcoal
producing facility, or an independent operation, with charcoal being received as raw material.
Figure 10.7-3 presents a flow diagram for charcoal briquette production. Raw charcoal is first
crushed to pass through an approximately 3 millimeter (0.12 inch) screen aperture and then stored for
briquetting. The charcoal is then mixed with a binder to form a 65 to 70 percent charcoal mixture.
Typical binder solutions are 9 to 10 percent by weight solutions of cornstarch, milostarch, or
wheatstarch. Sawdust or other materials may be added to obtain faster burning or higher
temperatures. Briquettes are then formed in a press and dried at approximately 135°C (275°F) for
3 to 4 hours, resulting in a product with a 5 percent moisture content. This process generates a
briquette of approximately 90 percent pyrolysis product.
10.7.2 Emissions And Controls3'12
There are five types of products and byproducts from charcoal production operations:
charcoal, noncondensible gases (carbon monoxide [CO], carbon dioxide [COJ, methane, and ethane),
pyroacids (primarily acetic acid and methanol), tars and heavy oils, and water. With the exception of
charcoal, all of these materials are emitted with the kiln exhaust. Product constituents and the
distribution of these constituents vary, depending on raw materials and carbonization parameters.
Organics and CO are naturally combusted to CO2 and water before leaving the retort. Because the
extent of this combustion varies from plant to plant, emission levels are quite variable. Some of the
9/95 Wood Products Industry 10.7-1
-------
ROOF VENTILATION
PORTS
CLAY PIPE STACKS
AIR
PIPK
STEEL DOORS
CONCRETE WALLS
AND ROOF
Figure 10.7-1. The Missouri-type charcoal kiln.7
(Source Classification Code: 3-01-006-03.)
10.7-2
EMISSION FACTORS
9/95
-------
POM EMISSIONS
COMBUSTION
ZONE
COOLING
ZONE
CHARCOAL
PRODUCT
COOLING AIR FAN
COOLING AIR DISCHARGE
FLOATING DAMPER
///////////V
FEED MATERIAL
RABBLE ARM AT
EACH HEARTH
COMBUSTION
"AIR RETURN
RABBLE ARM
DRIVE
Figure 10.7-2. The continuous multiple hearth kiln for charcoal production.4
(Source Classification Code: 3-01-006-04.)
9/95
Wood Products Industry
10.7-3
-------
ELEVATOR
LUMP
CHARCOAL
STORAGE
CHARCOAL
FEEDER
SCREEN
GROUND
CHARCOAL
STORAGE
STACK
STARCH
STORAGE
AND
FEEDER
COOLING ELEVATOR
Figure 10.7-3. Flow diagram for charcoal briquette production.3
(Source Classification Code: 3-01-006-05.)
10.7-4
EMISSION FACTORS
9/95
-------
specific organic compounds that may be found in charcoal kiln emissions include ethane, methane,
ethanol, and polycyclic organic matter (POM). If uncombusted, tars may solidify to form PM
emissions, and pyroacids may form aerosol emissions.
The charcoal briquetting process is also a potential source of emissions. The crushing,
screening, and handling of the dry raw charcoal may produce PM and PM-10 emissions. Briquette
pressing and drying may be a source of VOC emissions, depending on the type of binder and other
additives used.
Continuous production of charcoal is more amenable to emission control than batch
production because emission composition and flow rate are relatively constant. Emissions from
continuous multiple hearth charcoal kilns generally are controlled with afterburners. Cyclones, which
commonly are used for product recovery, also reduce PM emissions from continuous kilns.
Afterburning is estimated to reduce emissions of PM, CO, and VOC by at least 80 percent. Control
of emissions from batch-type charcoal kilns is difficult because the process and, consequently, the
emissions are cyclic. Throughout a cycle, both the emission composition and flow rate change.
Batch kilns do not typically have emission control devices, but some may use after-burners.
Particulate matter emissions from briquetting operations can be controlled with a centrifugal
collector (65 percent control) or fabric filter (99 percent control).
Emission factors for criteria pollutant emissions from the manufacture of charcoal are shown
in Table 10.7-1. Table 10.7-2 presents factors for emission of organic pollutants from charcoal
manufacturing.
Table 10.7-1 EMISSION FACTORS FOR CHARCOAL MANUFACTURING-
CRITERIA POLLUTANTS AND CO2a
EMISSION FACTOR RATING: E
Source
Charcoal kilnc (SCC 3-01-006-03, -04)
Briquetting11 (SCC 3-01-006-05)
Ib/ton
Total PMb
310"
56f
NOX
24°
ND
CO
290f
ND
VOC
270s
ND
CO2
l,100f
ND
a Factors represent uncontrolled emissions. SCC = Source Classification Code. ND = no data.
Emission factors units are Ib/ton of product. One Ib/ton = 0.5 kg/Mg.
b Includes condensibles and consists primarily of tars and oils.
c Applicable to both batch and continuous kilns.
d References 2,6-7.
e Reference 3. Based on 0.14 percent nitrogen content of wood.
f References 2,6-7,11.
g References 2-3,6.
h For entire briquetting process.
9/95
Wood Products Industry
10.7-5
-------
Table 10.7-2. EMISSION FACTORS FOR CHARCOAL MANUFACTURING-
MISCELLANEOUS ORGANIC POLLUTANTS"
EMISSION FACTOR RATING: E
Source
Charcoal kilnb (SCC 3-01-006-3, -04)
Pollutant
Methane0
Ethaned
Methanol6
POMf
Emission factor, Ib/ton
110
52
150
0.0095
a Factors represent uncontrolled emissions. SCC = Source Classification Code. Emission factors
units are Ib/ton of product. One Ib/ton = 0.5 kg/Mg.
b Applicable to both batch and continuous kilns.
c References 2,6.
d References 3,6.
e Reference 2.
f Reference 7.
References For Section 10.7
1. Air Pollutant Emission Factors, APTD-0923, U. S. Environmental Protection Agency,
Research Triangle Park, NC, April 1970.
2. R. N. Shreve, Chemical Process Industries, Third Edition, McGraw-Hill, NY, 1967.
3. C. M. Moscowitz, Source Assessment: Charcoal Manufacturing State of the Art,
EPA-600/2-78-004z, U. S. Environmental Protection Agency, Cincinnati, OH, December
1978.
4. Radian Corporation, Locating And Estimating Air Emissions From Sources OfPolycyclic
Organic Matter (POM), EPA-450/4-84-007p, U. S. Environmental Protection Agency,
Research Triangle Park, NC, May 1988.
5. Riegel's Handbook Of Industrial Chemistry, Seventh Edition, J. A. Kent, ed., Van Nostrand
Reinhold, NY, 1974.
6. J. R. Hartwig, "Control of Emissions from Batch-Type Charcoal Kilns", Forest Products
Journal, 27(9):49-50, April 1971.
7. W. H. Maxwell, Stationary Source Testing Of A Missouri-Type Charcoal Kiln,
EPA-907/9-76-001, U. S. Environmental Protection Agency, Kansas City, MO, August 1976.
8. R. W. Rolke, et al., Afterburner Systems Study, EPA-RZ-72-062, U. S. Environmental
Protection Agency, Research Triangle Park, NC, August 1972.
9. B. F. Keeling, Emission Testing The Missouri-Type Charcoal Kiln, Paper 76-37.1, presented
at the 69th Annual Meeting of the Air Pollution Control Association, Portland, OR, June
1976.
10.7-6 EMISSION FACTORS 9/95
-------
10. P. B. Hulman, et al, Screening Study On Feasibility Of Standards Of Performance For Wood
Charcoal Manufacturing, EPA Contract No. 68-02-2608, Radian Corporation, Austin, TX,
August 1978.
11. Emission Test Report, Kingsford Charcoal, Bumside, Kentucky, prepared by Monsanto
Research Corporation for U. S. Environmental Protection Agency, Research Triangle Park,
NC, August 1980.
12. Written communication from J. Swiskow, Barbecue Industry Association, Naperville, IL, to
D. Safriet, U. S. Environmental Protection Agency, Research Triangle Park, NC,
February 11, 1994.
9/95 Wood Products Industry 10.7-7
-------
10.8 Wood Preserving
[Work In Progress]
1/95 Wood Products Industry 10.8-1
-------
11. MINERAL PRODUCTS INDUSTRY
The production, processing, and use of various minerals are characterized by paniculate
emissions in the form of dust. Frequently, as in the case of crushing and screening, this dust is
identical in composition to the material being handled. Emissions occur also from handling and
storing the finished product because this material is often dry and fine. Paniculate emissions from
some of the processes such as quarrying, yard storage, and dust from transport are difficult to
control, but most can be reduced by conventional paniculate control equipment such as cyclones,
scrubbers, and fabric filters. Because of the wide variety in processing equipment and final products,
emission levels will range widely.
1/95 Mineral Products Industry 11.0-1
-------
11.1 Hot Mix Asphalt Plants
11.1.1 General1'2'23'42-43
Hot mix asphalt (HMA) paving materials are a mixture of well-graded, high-quality aggregate
(which can include reclaimed asphalt pavement [RAP]) and liquid asphalt cement, which is heated and
mixed in measured quantities to produce HMA. Aggregate and RAP (if used) constitute over
92 percent by weight of the total mixture. Aside from the amount and grade of asphalt cement used,
mix characteristics are determined by the relative amounts and types of aggregate and RAP used. A
certain percentage of fine aggregate (less than 74 micrometers [/im] in physical diameter) is required
for the production of good quality HMA.
Hot mix asphalt paving materials can be manufactured by: (1) batch mix plants,
(2) continuous mix (mix outside drum) plants, (3) parallel flow drum mix plants, and (4) counterflow
drum mix plants. This order of listing generally reflects the chronological order of development and
use within the HMA industry.
There are approximately 3,600 active asphalt plants in the United States. Of these,
approximately 2,300 are batch plants, 1,000 are parallel flow drum mix plants, and 300 are
counterflow drum mix plants. About 85 percent of plants being manufactured today are of the
counterflow drum mix design, while batch plants and parallel flow drum mix plants account for
10 percent and 5 percent, respectively. Continuous mix plants represent a very small fraction of the
plants in use (<0.5 percent) and, therefore, are not discussed further.
An HMA plant can be constructed as a permanent plant, a skid-mounted (easily relocated)
plant, or a portable plant. All plants can have RAP processing capabilities. Virtually all plants being
manufactured today have RAP processing capability.
Batch Mix Plants -
Figure 11.1-1 shows the batch mix HMA production process. Raw aggregate normally is
stockpiled near the plant. The bulk aggregate moisture content typically stabilizes between 3 to
5 percent by weight.
Processing begins as the aggregate is hauled from the storage piles and is placed in the
appropriate hoppers of the cold feed unit. The material is metered from the hoppers onto a conveyer
belt and is transported into a rotary dryer (typically gas- or oil-fired). Dryers are equipped with
flights designed to shower the aggregate inside the drum to promote drying efficiency.
As the hot aggregate leaves the dryer, it drops into a bucket elevator and is transferred to a
set of vibrating screens where it is classified into as many as 4 different grades (sizes), and is dropped
into individual "hot" bins according to size. To control aggregate size distribution in the final batch
mix, the operator opens various hot bins over a weigh hopper until the desired mix and weight are
obtained. Reclaimed asphalt pavement may be added at this point, also. Concurrent with the
aggregate being weighed, liquid asphalt cement is pumped from a heated storage tank to an asphalt
bucket, where it is weighed to achieve the desired aggregate-to-asphalt cement ratio in the final mix.
The aggregate from the weigh hopper is dropped into the mixer (pug mill) and dry-mixed for
6 to 10 seconds. The liquid asphalt is then dropped into the pug mill where it is mixed for an
1795 Mineral Products Industry 11.1-1
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EMISSION FACTORS
1/95
-------
additional period of time. Total mixing time is usually less than 60 seconds. Then the hot mix is
conveyed to a hot storage silo or is dropped directly into a truck and hauled to the job site.
Parallel Flow Drum Mix Plants -
Figure 11.1-2 shows the parallel flow drum mix process. This process is a continuous mixing
type process, using proportioning cold feed controls for the process materials. The major difference
between this process and the batch process is that the dryer is used not only to dry the material but
also to mix the heated and dried aggregates with the liquid asphalt cement. Aggregate, which has
been proportioned by size gradations, is introduced to the drum at the burner end. As the drum
rotates, the aggregates, as well as the combustion products, move toward the other end of the drum in
parallel. Liquid asphalt cement flow is controlled by a variable flow pump electronically linked to the
new (virgin) aggregate and RAP weigh scales. The asphalt cement is introduced in the mixing zone
midway down the drum in a lower temperature zone, along with any RAP and paniculate matter
(PM) from collectors.
The mixture is discharged at the end of the drum and is conveyed to either a surge bin or
HMA storage silos. The exhaust gases also exit the end of the drum and pass on to the collection
system.
Parallel flow drum mixers have an advantage, in that mixing in the discharge end of the drum
captures a substantial portion of the aggregate dust, therefore lowering the load on the downstream
collection equipment. For this reason, most parallel flow drum mixers are followed only by primary
collection equipment (usually a baghouse or venturi scrubber). However, because the mixing of
aggregate and liquid asphalt cement occurs in the hot combustion product flow, organic emissions
(gaseous and liquid aerosol) may be greater than in other processes.
Counterflow Drum Mix Plants -
Figure 11.1-3 shows a counterflow drum mix plant. In this type of plant, the material flow in
the drum is opposite or counterflow to the direction of exhaust gases. In addition, the liquid asphalt
cement mixing zone is located behind the burner flame zone so as to remove the materials from direct
contact with hot exhaust gases.
Liquid asphalt cement flow is controlled by a variable flow pump which is electronically
linked to the virgin aggregate and RAP weigh scales. It is injected into the mixing zone along with
any RAP and particulate matter from primary and secondary collectors.
Because the liquid asphalt cement, virgin aggregate, and RAP are mixed in a zone removed
from the exhaust gas stream, counterflow drum mix plants will likely have organic emissions (gaseous
and liquid aerosol) that are lower than parallel flow drum mix plants. A counterflow drum mix plant
can normally process RAP at ratios up to 50 percent with little or no observed effect upon emissions.
Today's counterflow drum mix plants are designed for improved thermal efficiencies.
Recycle Processes -
In recent years, die use of RAP has been initiated in the HMA industry. Reclaimed asphalt
pavement significantly reduces the amount of virgin rock and asphalt cement needed to produce
HMA.
In the reclamation process, old asphalt pavement is removed from the road base. This
material is then transported to the plant, and is crushed and screened to the appropriate size for
further processing. The paving material is then heated and mixed with new aggregate (if applicable),
and the proper amount of new asphalt cement is added to produce a high-quality grade of HMA.
1/95 Mineral Products Industry 11.1-3
-------
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Mineral Products Industry
11.1-5
-------
11.1.2 Emissions And Controls23-42"43
Emission points discussed below refer to Figure 11.1-1 for batch mix asphalt plants, and to
Figure 11.1-2 and Figure 11.1-3 for drum mix plants.
Batch Mix Plants -
As with most facilities in the mineral products industry, batch mix HMA plants have 2 major
categories of emissions: ducted sources (those vented to the atmosphere through some type of stack,
vent, or pipe), and fugitive sources (those not confined to ducts and vents but emitted directly from
the source to the ambient air). Ducted emissions are usually collected and transported by an
industrial ventilation system having 1 or more fans or air movers, eventually to be emitted to the
atmosphere through some type of stack. Fugitive emissions result from process and open sources and
consist of a combination of gaseous pollutants and PM.
The most significant source of ducted emissions from batch mix HMA plants is the rotary
drum dryer. Emissions from the dryer consist of water as steam evaporated from the aggregate, PM,
and small amounts of volatile organic compounds (VOC) of various species (including hazardous air
pollutants [HAP]) derived from combustion exhaust gases.
Other potential process sources include the hot-side conveying, classifying, and mixing
equipment, which are vented to either the primary dust collector (along with the dryer gas) or to a
separate dust collection system. The vents and enclosures that collect emissions from these sources
are commonly called "fugitive air" or "scavenger" systems. The scavenger system may or may not
have its own separate ah* mover device, depending on the particular facility. The emissions captured
and transported by the scavenger system are mostly aggregate dust, but they may also contain gaseous
VOCs and a fine aerosol of condensed liquid particles. This liquid aerosol is created by the
condensation of gas into particles during cooling of organic vapors volatilized from the asphalt cement
in the mixer (pug mill). The amount of liquid aerosol produced depends to a large extent on the
temperature of the asphalt cement and aggregate entering the pug mill. Organic vapor and its
associated aerosol are also emitted directly to the atmosphere as process fugitives during truck
loadout, from the bed of the truck itself during transport to the job site, and from the asphalt storage
tank. In addition to low molecular weight VOCs, these organic emission streams may contain small
amounts of polycyclic compounds. Both the low molecular weight VOCs and the polycyclic organic
compounds can include HAPs. The ducted emissions from the heated asphalt storage tanks may
include VOCs and combustion products from the tank heater.
The choice of applicable control equipment for the dryer exhaust and vent line ranges from
dry mechanical collectors to scrubbers and fabric collectors. Attempts to apply electrostatic
precipitators have met with little success. Practically all plants use primary dust collection equipment
with large diameter cyclones, skimmers, or settling chambers. These chambers are often used as
classifiers to return collected material to the hot elevator and to combine it with the drier aggregate.
To capture remaining PM, the primary collector effluent is ducted to a secondary collection device.
Most plants use either a baghouse or a venturi scrubber for secondary emissions control.
There are also a number of fugitive dust sources associated with batch mix HMA plants,
including vehicular traffic generating fugitive dust on paved and unpaved roads, aggregate material
handling, and other aggregate processing operations. Fugitive dust may range from 0.1 /zm to more
than 300 /zm in aerodynamic diameter. On average, 5 percent of cold aggregate feed is less than
74 /tm (minus 200 mesh). Fugitive dust that may escape collection before primary control generally
consists of PM with 50 to 70 percent of the total mass less than 74 /on. Uncontrolled PM emission
11.1-6 EMISSION FACTORS 1/95
-------
factors for various types of fugitive sources in HMA plants are addressed in Section 13.2.3, "Heavy
Construction Operations".
Parallel Flow Drum Mix Plants -
The most significant ducted source of emissions is the rotary drum dryer. Emissions from the
drum consist of water as steam evaporated from the aggregate, PM, and small amounts of VOCs of
various species (including HAPs) derived from combustion exhaust gases, liquid asphalt cement, and
RAP, if utilized. The VOCs result from incomplete combustion and from the heating and mixing of
liquid asphalt cement inside the drum. The processing of RAP materials may increase VOC
emissions because of an increase in mixing zone temperature during processing.
Once the VOCs cool after discharge from the process stack, some condense to form a fine
liquid aerosol or "blue smoke" plume. A number of process modifications or restrictions have been
introduced to reduce blue smoke including installation of flame shields, rearrangement of flights
inside the drum, adjustments of the asphalt injection point, and other design changes.
Counterflow Drum Mix Plants -
The most significant ducted source of emissions is the rotary drum dryer in a counterflow
drum mix plant. Emissions from the drum consist of water as steam evaporated from the aggregate,
PM, and small amounts of VOCs of various species (including HAPs) derived from combustion
exhaust gases, liquid asphalt cement, and RAP, if used.
Because liquid asphalt cement, aggregate, and sometimes RAP, are mixed in a zone not in
contact with the hot exhaust gas stream, counterflow drum mix plants will likely have lower VOC
emissions than parallel flow drum mix plants. The organic compounds that are emitted from
counterflow drum mix plants are likely to be products of a slight inefficient combustion and can
include HAP.
Parallel and Counterflow Drum Mix Plants -
Process fugitive emissions associated with batch plant hot screens, elevators, and the mixer
(pug mill) are not present in the drum mix processes. However, there may be slight fugitive VOC
emissions from transport and handling of the hot mix from the drum mixer to the storage silo and
also from the load-out operations to the delivery trucks. Since the drum process is continuous, these
plants must have surge bins or storage silos. The fugitive dust sources associated with drum mix
plants are similar to those of batch mix plants with regard to truck traffic and to aggregate material
feed and handling operations.
Tables 11.1-1 and 11.1-2 present emission factors for filterable PM and PM-10, condensable
PM, and total PM for batch mix HMA plants. The emission factors are based on both the type of
control technology employed and the type of fuel used to fire the dryer. Particle size data for batch
mix HMA plants, also based on the control technology used, are shown in Table 11.1-3.
Tables 11.1-4 and 11.1-5 present filterable PM and PM-10, condensable PM, and total PM emission
factors for drum mix HMA plants. The emission factors are based on both the type of control
technology employed and the type of fuel used to fire the dryer. Particle size data for drum mix
HMA plants, also based on the control technology used, are shown in Table 11.1-6. Tables 11.1-7
and 11.1-8 present emission factors for carbon monoxide (CO), carbon dioxide (CO2), nitrogen
oxides (NOX), sulfur dioxide (SO2), and total organic compounds (TOC) from batch and drum mix
plants. Table 11.1-9 presents organic pollutant emission factors for batch plants. Tables 11.1-10 and
11.1-11 present organic pollutant emission factors for drum mix plants. Tables 11.1-12 and 11.1-13
present metal emission factors for batch and drum mix plants, respectively.
1195 Mineral Products Industry 11.1-7
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-------
Table 11.1-3. SUMMARY OF PARTICLE SIZE DISTRIBUTION
FOR BATCH MIX HOT MIX ASPHALT PLANTS*
Particle
Size, fimb
2.5
5.0
10.0
15.0
20.0
Cumulative Mass Less Than Or Equal To Stated Size (%)c
Uncontrolled
0.83
3.5
14
23
30
Cyclone
Collectors
5.0
11
21
29
36
Multiple Centrifugal
Scrubbers
67
74
80
83
84
Gravity Spray
Towers
21
27
37
39
41
Fabric
Filters
33
36
40
47
54
a Reference 23, Table 3-36. Rounded to two significant figures.
b Aerodynamic diameter.
c Applies only to the mass of filterable PM.
Table 11.1-4 (Metric Units). EMISSION FACTORS FOR DRUM MIX HOT MIX
ASPHALT PLANTS3
EMISSION FACTOR RATING: D (except as noted)
Process
Natural gas-fired dryer
(SCC 3-05-002-05)
Uncontrolled
Venturi scrubber
Fabric filter
Oil-fired dryer
(SCC 3-05-002-05)
Uncontrolled
Venturi scrubber
Fabric filter
Filterable PM
PM | PM-10C
9.4d 2.2
0.01 7« ND
0.007011 0.0022
9.4d 2.2
0.0178 ND
O.OOlCf1 0.0022
Condensable PM
Inorganic
0.0146
ND
ND
0.012e
ND
0.012k
Organic
0.027f
0.010f
ND
0.0013e
ND
0.0013k
Total
0.041
ND
0.0019J
0.0136
ND
0.013k
Total PMb
PM | PM-10
9.4 2.2
ND ND
0.0089 0.0041
9.4 2.2
ND ND
0.020 0.015
a Factors are kg/Mg of product. Tests included dryers that were processing reclaimed asphalt
pavement (RAP). Because of the limited data available, the effect of RAP processing on emissions
could not be determined. Filterable PM emission factors were developed from tests on dryers firing
several different fuels. SCC = Source Classification Code. ND = no data.
b Total PM emission factors are the sum of filterable PM and total condensable PM emission factors.
Total PM-10 emission factors are the sum of filterable PM-10 and total condensable PM emission
factors.
c Particle size data from Reference 23 were used in conjunction with the filterable PM emission
factors shown.
d References 31,36-38.
^ Although no emission test data are available for uncontrolled condensible PM, values are assumed
to be equal to the maximum controlled value measured.
References 36-37.
$ References 29,32,36-37,40.
h References 25-28,31,33,40. EMISSION FACTOR RATING: C.
J Reference 39.
k References 25,39.
f
11.1-10
EMISSION FACTORS
1/95
-------
Table 11.1-5 (English Units). EMISSION FACTORS FOR DRUM MIX HOT MIX
ASPHALT PLANTSa
EMISSION FACTOR RATING: D (except as noted)
Process
Natural gas-fired dryer
(SCC 3-05-002-05)
Uncontrolled
Venturi scrubber
Fabric filter
Dryer (oil-fired)
(SCC 3-05-002-05)
Uncontrolled
Venturi scrubber
Fabric filter
Filterable PM
PM
19d
0.033S
0.014h
19d
0.033B
0.014h
PM-10C
4.3
ND
0.0045
4.3
ND
0.0045
Condensable PM
Inorganic | Organic
0.0276 0.054f
ND 0.020f
ND ND
0.0236 0.0026e
ND ND
0.023k 0.0026k
Total
0.081
ND
0.00371
0.026e
ND
0.026k
Total
PM
19
ND
0.018
19
ND
0.040
PMb
PM-10
4.4
ND
0.0082
4.3
ND
0.031
a Factors are Ib/ton of product. Tests included dryers that were processing reclaimed asphalt
pavement (RAP). Because of the limited data available, the effect of RAP processing on emissions
could not be determined. Filterable PM emission factors were developed from tests on dryers firing
several different fuels. SCC = Source Classification Code. ND = no data.
b Total PM emission factors are the sum of filterable PM and total condensable PM emission factors.
Total PM-10 emission factors are the sum of filterable PM-10 and total condensable PM emission
factors.
c Particle size data from Reference 23 were used in conjunction with the filterable PM emission
factors shown.
d References 31,36-38.
e Although no emission test data are available for uncontrolled condensable PM, values are assumed
to be equal to the maximum controlled value measured.
f References 36-37.
S References 29,32,36-37,40.
h References 25-28,31,33,40. EMISSION FACTOR RATING: C.
J Reference 39.
k References 25,39.
Table 11.1-6. SUMMARY OF PARTICLE SIZE DISTRIBUTION
FOR DRUM MIX HOT MIX ASPHALT PLANTS'1
Particle Size, /xmb
2.5
10.0
15.0
Cumulative Mass Less Than Or Equal To Stated Size (%)c
Uncontrolled
5.5
23
27
Fabric Filters'1
11
32
35
a Reference 23, Table 3-35. Rounded to two significant figures.
b Aerodynamic diameter.
c Applies only to the mass of filterable PM.
d Includes data from two out of eight tests where about 30% reclaimed asphalt pavement was
processed using a split feed process.
1/95
Mineral Products Industry
11.1-11
-------
Table 11.1-7 (Metric And English Units). EMISSION FACTORS FOR BATCH MIX
HOT MIX ASPHALT PLANTS*
EMISSION FACTOR RATING: D
Process
Natural gas-fired dryer
(SCC 3-05-002-01)
Oil-fired dryer
(SCC 3-05-002-01)
CO
kg/Mg
0.17°
0.035°
Ib/ton
0.34°
0.069e
C02
kg/Mg
17"
198
Ib/ton
35d
398
NOX
kg/Mg | Ib/ton
0.013° 0.025C
o.os4e o.ir
SO2
kg/Mg | Ib/ton
0.00256 0.00506
0.12e 0.24e
TOCb
kg/Mg J^ Ib/ton
0.0084f 0.017f
0.023f 0.046f
a Factors are kg/Mg and Ib/ton of product. Factors are for uncontrolled emissions, unless noted.
SCC = Source Classification Code.
b Factors represent TOC as methane, based on EPA Method 25A test data.
c References 24,34,39.
d References 15,24,39.
e Reference 39. Dryer tested was fired with #6 fuel oil. Dryers fired with other fuel oils will have
different S02 emission factors.
f References 24,39.
g References 15,39.
Table 11.1-8 (Metric And English Units). EMISSION FACTORS FOR DRUM MIX
HOT MIX ASPHALT PLANTS3
EMISSION FACTOR RATING: D
Process
Natural gas-fired dryer
(SCC 3-05-002-01)
Oil-fired dryer
(SCC 3-05-002-01)
CO
kg/Mg
0.028C
0.0186
Ib/ton
0.056C
0.0366
CO2
kg/Mg | Ib/ton
14d 27d
19f 37f
NOX
kg/Mg
0.015C
0.0388
Ib/ton
0.030C
0.0758
S02
kg/Mg
0.0017C
0.0288
Ib/ton
0.0033C
0.0568
TOCb
kg/Mg | Ib/ton
0.025C 0.051C
0.0358 0.0698
a Factors are kg/Mg and Ib/ton of product. Factors represent uncontrolled emissions, unless noted.
Tests included dryers that were processing reclaimed asphalt pavement (RAP). Because of limited
data, the effect of RAP processing on emissions could not be determined.
SCC = Source Classification Code.
b Factors represent TOC as methane, based on EPA Method 25A test data.
c Reference 39. Includes data from both parallel flow and counterflow drum mix dryers. Organic
compound emissions from counterflow systems are expected to be smaller than from parallel flow
systems. However, the available data are insufficient to accurately quantify the difference in these
emissions.
d References 30,39.
e Reference 25.
f References 25-27,29,32-33,39.
8 References 25,39. Includes data from both parallel flow and counterflow drum mix dryers.
Organic compound emissions from counterflow systems are expected to be smaller than from
parallel flow systems. However, the available data are insufficient to accurately quantify the
difference in these emissions. One of the dryers tested was fired with #2 fuel oil (0.003 kg/Mg
[0.006 Ib/ton]) and the other dryer was fired with waste oil (0.05 kg/Mg [0.1 Ib/ton]). Dryers fired
with other fuel oils will have different SO2 emission factors.
11.1-12
EMISSION FACTORS
1/95
-------
Table 11.1-9 (Metric And English Units). EMISSION FACTORS FOR ORGANIC POLLUTANT
EMISSIONS FROM BATCH MIX HOT MIX ASPHALT PLANTS*
EMISSION FACTOR RATING: D (except as noted)
Process
Natural gas-fired dryer
(SCC 3-05-002-01)
Oil-fired dryer
(SCC 3-05-002-01)
CASRN
91-57-6
83-32-9
208-96-8
75-07-0
67-64-1
120-12-7
100-52-7
71-43-2
56-55-3
205-99-2
207-08-9
78-84-2
218-01-9
4170-30-3
100-41-4
206-44-0
86-73-7
50-00-0
66-25-1
74-82-8
91-20-3
85-01-8
129-00-0
106-51-4
108-88-3
1330-20-7
91-57-6
206-44-0
50-00-0
91-20-3
85-01-8
129-00-0
Pollutant
Name
2-Methylnaphthaleneb
Acenaphtheneb
Acenaphthyleneb
Acetaldehyde
Acetone
Anthracene1*
Benzaldehyde
Benzene
Benzo(a)anthraceneb
Benzo(b)fluorantheneb
Benzo(k)fluorantheneb'c
Butyraldehyde/
Isobutyraldehyde
Chryseneb
Crotonaldehyde
Ethyl benzene
Fluorantheneb
Fluoreneb
Formaldehyde
Hexanal
Methane
Naphthaleneb
Phenanthreneb
Pyreneb
Quinone
Toluene
Xylene
2-Methyhiaphthaleneb
Fluorantheneb
Formaldehyde0
Methane
Naphthalene15
Phenanthreneb'°
Pyreneb
Emission Factor
kg/Mg
3.8x10-5
6.2X10'7
4.3xlO-7
0.00032
0.0032
l.SxlO'7
6.4xlO-5
0.00017
2.3xlO'9
2.3xlO-9
1.2xlO-8
l.SxlO-5
3.1xlO-9
l.SxlO-5
0.0016
1.6xlO-7
9.8xlO-7
0.00043
1.2xlO-5
0.0060
2.1xlO-5
1.6X10-6
3.1x10-8
0.00014
0.00088
0.0021
3.0x10-5
1.2x10-5
0.0016
0.0022
2.2x10-5
l.SxlO-5
2.7xlO-5
Ib/ton
7.7x10-5
1.2X10-6
8.6xlO-7
0.00064
0.0064
3.1xlO-7
0.00013
0.00035
4.5xlO'9
4.5xlO'9
2.4x10-8
3.0xlO-5
6.1xlO-9
2.9xlO-5
0.0033
S.lxlO'7
2.0X10"6
0.00086
2.4xlO-5
0.012
4.2xlO-5
3.3X10-6
6.2x10-8
0.00027
0.0018
0.0043
6.0xlO-5
2.4xlO-5
0.0032
0.0043
4.5x10-5
3.7xlO-5
5.5x10-5
Ref.
Nos.
24,39
34,39
34,39
24
24
34,39
24
24,39
39
39
34
24
39
24
24,39
34,39
34,39
24,39
24
39
34,39
34,39
34,39
24
24,39
24,39
39
39
39,40
39
39
39
39
a Factors are kg/Mg and Ib/ton of hot mix asphalt produced. Factors represent uncontrolled
emissions, unless noted. CASRN = Chemical Abstracts Service Registry Number.
SCC = Source Classification Code.
b Controlled by a fabric filter. Compound is classified as polycyclic organic matter (POM), as
defined in the 1990 Clean Air Act Amendments (CAAA).
c EMISSION FACTOR RATING: E.
1/95
Mineral Products Industry
11.1-13
-------
Table 11.1-10 (Metric And English Units). EMISSION FACTORS FOR ORGANIC POLLUTANT
EMISSIONS FROM DRUM MIX HOT MIX ASPHALT PLANTS*
EMISSION FACTOR RATING: D (except as noted)
Process
Natural gas- or
propane-fired dryer1*
(SCC 3-05-002-05)
Oil-fired dryer0
(SCC 3-05-002-05)
CASRN
91-58-7
91-57-6
83-32-9
208-96-8
120-12-7
71-43-2
56-55-3
50-32-8
205-99-2
192-97-2
191-24-2
207-08-9
218-01-9
53-70-3
100^1-4
206-44-0
86-73-7
50-00-0
50-00-0
193-39-5
74-82-8
71-55-6
91-20-3
198-55-0
85-01-8
129-00-0
108-88-3
1330-20-7
91-57-6
208-96-8
75-07-0
67-64-1
Pollutant
Name
2-Chloronaphthalenec
2-Methylnaphthalene°
Acenaphthenec
Acenaphthylene0
Anthracene0
Benzene
Benzo(a)anthracenec
Benzo(a)pyrenec
Benzo(b)fluoranthenec
Benzo(e)pyrene°
Benzo(g,h,i)perylenec
Benzo(k)fluoranthenec
Chrysene0
Dibenz(a,h)anthracenec>e
Ethylbenzene6
Fluoranthenec
Fluorenec
Formaldehyde
Formaldehyded'e
Indeno(l,2,3-cd)pyrenec
Methane
Methyl chloroform6
Naphthalene0
Perylenec>e
Phenanthrene0
Pyrene0
Toluene
Xylene
2-Methylnaphthalenec
Acenaphthylene0
Acetaldehyde
Acetone
Emission Factor
kg/Mg
8.9xlO'7
3.7xlO'5
6.4X10'7
4.2x10-*
l.OxlO'7
0.00060
l.OxlO'7
4.6xlO'9
S.lxlO'8
5.2xlO'8
1.9xlO-8
2.6xlO-8
l.SxlO-7
1.3xlO-9
0.00015
3.0xlO'7
2.7X10-6
0.0018
0.00079
3.6xlO'9
0.010
2.4X10'5
2.4xlO'5
6.2xlO'9
4.2xlO'6
2.3xlO'7
0.00010
0.00020
8.5xlO-5
l.lxlO'5
0.00065
0.00042
Ib/ton
l.SxlO"6
7.4xlO'5
1.3X10-6
8.4X10-6
2.1xlO'7
0.0012
2.0xlO-7
9.2xlO-9
l.OxlO'7
l.OxlO'7
3.9xlO-8
5.3xlO-8
3.5xlO-7
2.7X10'9
0.00029
5.9xlO-7
5.3X10"6
0.0036
0.0016
7.3xlO'9
0.021
4.8xlO-5
4.8xlO-5
1.2xlO-8
8.4X10-6
4.6X10'7
0.00020
0.00040
0.00017
2.2X10'5
0.0013
0.00083
Ref.
Nos.
39
39
35,39
35,39
35,39
39
39
39
35,39
39
39
39
39
39
39
35,39
35,39
35,39
40
39
39
35
35,39
39
35,39
35,39
35,39
39
39
39
25
25
11.1-14
EMISSION FACTORS
1/95
-------
Table 11.1-10 (cont.).
Process
CASRN
107-02-8
120-12-7
100-52-7
71-43-2
78-84-2
4170-30-3
100-41-4
86-73-7
50-00-0
50-00-0
66-25-1
590-86-3
74-82-8
78-93-3
91-20-3
85-01-8
123-38-6
129-00-0
106-51-4
Pollutant
Name
Acrolein
Anthracene0
Benzaldehyde
Benzene
Butyraldehyde/Isobutyraldehyde
Crotonaldehyde
Ethylbenzene
Fluorene0
Formaldehyde
Formaldehyde4-6
Hexanal
Isovaleraldehyde
Methane
Methyl ethyl ketone
Naphthalene6
Phenanthrene6
Propionaldehyde
Pyrenec>e
Quinone
108-88-3 Toluene
110-62-3
Valeraldehyde
1330-20-7 Xylene
Emission Factor
kg/Mg
1.3xlO-5
l.SxKr6
5.5xlO-5
0.00020
S.OxlO'5
4.3xlO'5
0.00019
S.SxlO-6
0.0012
0.00026
5.5xlO"5
1.6xlO-5
0.0096
LOxlO'5
0.00016
2.8xlO'5
6.5xlO'5
l.SxlO-6
S.OxlO'5
0.00037
3.4xlO'5
8.2X10'5
Ib/ton
2.6xlO'5
3.6X10-6
0.00011
0.00041
0.00016
8.6xlO'5
0.00038
1.7xlO-5
0.0024
0.00052
0.00011
3.2xlO-5
0.020
2.0xlO'5
0.00031
5.5xlO'5
0.00013
3-OxlO-6
0.00016
0.00075
6.7xlO'5
0.00016
Ref.
Nos.
25
39
25
25
25
25
25
39
25,39
40
25
25
25,39
25
25,39
39
25
39
25
25
25
25
a Factors are kg/Mg and Ib/ton of hot mix asphalt produced. Table includes data from both parallel
flow and counterflow drum mix dryers. Organic compound emissions from counterflow systems
are expected to be less than from parallel flow systems, but the available data are insufficient to
quantify accurately the difference in these emissions. CASRN = Chemical Abstracts Service
Registry Number. SCC = Source Classification Code.
b Tests included dryers that were processing reclaimed asphalt pavement (RAP). Because of limited
data, the effect of RAP processing on emissions could not be determined.
c Controlled by a fabric filter. Compound is classified as polycyclic organic matter (POM), as
defined in the 1990 Clean Air Act Amendments (CAAA).
d Controlled by a wet scrubber.
e EMISSION FACTOR RATING: E
1/95
Mineral Products Industry
11.1-15
-------
Table U.l-11 (Metric And English Units). EMISSION FACTORS FOR ORGANIC POLLUTANT
EMISSIONS FROM HOT MIX ASPHALT HOT OIL HEATERS*
EMISSION FACTOR RATING: E
Process
Hot oil heater fired
with No.2 fuel oil
(SCC 3-05-002-08)
CASRN
83-32-9
208-96-8
120-12-7
205-99-2
206-44-0
86-73-7
50-00-0
91-20-3
85-01-8
129-00-0
19408-74-3
39227-28-6
35822-46-9
3268-87-9
67562-39-4
39001-02-0
Pollutant
Name
Acenaphtheneb
Acenaphthyleneb
Anthraceneb
Benzo(b)fluorantheneb
Fluorantheneb
Fluoreneb
Formaldehyde
Naphthalene15
Phenanthreneb
Pyreneb
1,2,3,7,8,9-HxCDD
1,2,3,4,7,8-HxCDD
HxCDD
1,2,3,4,6,7,8-HpCDD
HpCDD
OCDD
TCDFb
PeCDFb
HxCDFb
HpCDFb
1,2,3,4,6,7,8-HpCDF
OCDF
Emissior
kg/L
6.4xlO'8
2.4xlO'8
2.2xlO'8
1.2xlO-8
5.3xlO-9
3.8xlO'9
0.0032
2-OxlQ-6
5.9xlO-7
3.8xlO'9
9.1xlO'14
8.3xlO-14
7.4xlO'13
l.SxlO'12
2.4xlO'12
1.9xl(Tn
4-OxlO'13
5.8xlO'14
2.4xlO'13
1.2xlO-12
4.2xlO'13
1.4xlO-12
i Factor
Ib/gal
5.3xlO'7
2.0xlO'7
l.SxlO'7
l.OxlO-7
4.4xlO'8
3.2xlO'8
0.027
1.7X10'5
4.9X10-6
3.2xlO'8
7.6xlO-13
6.9xlO-13
6.2xlO'12
l.SxlO-11
2.0xlO-n
1.6xlO-10
3.3xlO-12
4.8xlO'13
2.0xlO-12
9.7xlO'12
3.5xlO-12
1.2xlO-n
a Reference 34. Factors are kg/L and Ib/gal of fuel consumed. Table includes data from both
parallel flow and counterflow drum mix dryers. Organic compound emissions from counterflow
systems are expected to be less than from parallel flow systems, but available data are insufficient to
quantify accurately the difference in these emissions. CASRN = Chemical Abstracts Service
Registry Number. SCC = Source Classification Code.
b Compound is classified as polycyclic organic matter (POM), as defined in the 1990 Clean Air Act
Amendments (CAAA).
11.1-16
EMISSION FACTORS
1/95
-------
Table 11.1-12 (Metric And English Units). EMISSION FACTORS FOR METAL EMISSIONS
FROM BATCH MIX HOT MIX ASPHALT PLANTS3
EMISSION FACTOR RATING: D (except as noted)
Process
Dryer
(SCC 3-05-002-01)
Pollutant
Arsenicb
Barium
Berylliumb
Cadmium
Chromium
Copper
Hexavalent chromiumb
Lead
Manganese
Mercury
Nickel
Seleniumb
Zinc
Emission Factor
kg/Mg
3.3xlO-7
7.3X10'7
l.lxlO"7
4.2xlQ-7
4.5xlO'7
1.8xlO-6
4.9xlO-9
3.7xlQ-7
S.OxlQ-6
2.3xlO"7
2.1xlO-6
4.6xlO'8
3.4xlQ-6
Ib/ton
6.6xlO-7
l.SxlO-6
2.2xlO'7
8.4xlO-7
8.9xlO'7
3.7X10"6
9.7xlO-9
7.4xlO'7
9.9xlO-6
4.5xlO'7
4,2xlO-6
9.2xlO'8
6.8xlO-6
Ref. Nos.
34,40
24
34
24,34
24
24,34
34
24,34
24,34
34
24,34
34
24,34
a Factors are kg/Mg and Ib/ton of hot mix asphalt produced.
SCC = Source Classification Code.
b EMISSION FACTOR RATING: E.
Emissions controlled by a fabric filter.
Table 11.1-13 (Metric And English Units). EMISSION FACTORS FOR METAL EMISSIONS
FROM DRUM MIX HOT MIX ASPHALT PLANTS3
EMISSION FACTOR RATING: D
Process
Dryerb
(SCC 3-05-002-05)
Pollutant
Arsenic
Barium
Cadmium
Chromium
Copper
Lead
Manganese
Mercury
Nickel
Phosphorus
Silver
Zinc
Emission Factor
kg/Mg
5.5xl(T7
2.4xlQ-6
2.2xlO-7
6.0xlO-6
3.1xlQ-6
1.7xlQ-6
5.5xlO-6
3.7xlO-9
7.5xlQ-6
2.8xlO-5
7.0xlO'7
2.1xlO'5
Ib/ton
l.lxlO-6
4.8xlO-6
4.4X1Q'7
1.2xlQ-5
6.1xlQ-6
3.3xlO-6
l.lxlO'5
7.3xlO-9
l.SxlO-5
5.5xlO-5
1.4xlO'6
4.2xlQ-5
Ref. Nos.
25,35
25
25,35
25
25
25,35
25
35
25
25
25
25,35
a Factors are kg/Mg and Ib/ton of hot mix asphalt produced.
SCC = Source Classification Code.
b Feed material includes RAP.
Emissions controlled by a fabric filter.
1/95
Mineral Products Industry
11.1-17
-------
References For Section 11.1
1. Asphaltic Concrete Plants Atmospheric Emissions Study, EPA Contract No. 68-02-0076,
Valentine, Fisher, and Tomlinson, Seattle, WA, November 1971.
2. Guide For Air Pollution Control Of Hot Mix Asphalt Plants, Information Series 17, National
Asphalt Pavement Association, Riverdale, MD, 1965.
•
3. R. M. Ingels, et al., "Control Of Asphaltic Concrete Batching Plants In Los Angeles
County", Journal Of The Air Pollution Control Association, 70(l):29-33, January 1960.
4. H. E. Friedrich, "Air Pollution Control Practices And Criteria For Hot Mix Asphalt Paving
Batch Plants", Journal Of The Air Pollution Control Association, 7P(12):924-928,
December 1969.
5. Air Pollution Engineering Manual, AP-40, U. S. Environmental Protection Agency, Research
Triangle Park, NC, 1973. Out of Print.
6. G. L. Allen, et al., "Control Of Metallurgical And Mineral Dust And Fumes In Los Angeles
County, California", Information Circular 7627, U. S. Department Of The Interior,
, Washington, DC, April 1952.
7. P. A. Kenline, Unpublished report on control of air pollutants from chemical process
industries, U. S. Environmental Protection Agency, Cincinnati, OH, May 1959.
8. Private communication between G. Sallee, Midwest Research Institute, Kansas City, MO, and
U. S. Environmental Protection Agency, Research Triangle Park, NC, June 1970.
9. J. A. Danielson, "Unpublished Test Data From Asphalt Batching Plants, Los Angeles County
Air Pollution Control District", presented at Air Pollution Control Institute, University Of
Southern California, Los Angeles, CA, November 1966.
10. M. E. Fogel, et al., Comprehensive Economic Study Of Air Pollution Control Costs For
Selected Industries And Selected Regions, R-OU-455, U. S. Environmental Protection
Agency, Research Triangle Park, NC, February 1970.
11. Preliminary Evaluation Of Air Pollution Aspects Of The Drum Mix Process,
EPA-340/1-77-004, U. S. Environmental Protection Agency, Research Triangle Park, NC,
March 1976.
12. R. W. Beaty and B. M. Bunnell, "The Manufacture Of Asphalt Concrete Mixtures In The
Dryer Drum", presented at the Annual Meeting of the Canadian Technical Asphalt
Association, Quebec City, Quebec, November 19-21, 1973.
13. J. S. Kinsey, "An Evaluation Of Control Systems And Mass Emission Rates From Dryer
Drum Hot Asphalt Plants", Journal Of The Air Pollution Control Association,
26(12): 1163-1165, December 1976.
14. Background Information For Proposed New Source Performance Standards, APTD-1352A and
B, U. S. Environmental Protection Agency, Research Triangle Park, NC, June 1973.
11.1-18 EMISSION FACTORS 1/95
-------
15. Background Information For New Source Performance Standards, EPA 450/2-74-003,
U. S. Environmental Protection Agency, Research Triangle Park, NC, February 1974.
16. Z. S. Kahn and T. W. Hughes, Source Assessment: Asphalt Paving Hot Mix,
EPA-600/2~77-107n, U. S. Environmental Protection Agency, Cincinnati, OH, December
1977.
17. V. P. Puzinauskas and L. W. Corbett, Report On Emissions From Asphalt Hot Mixes,
RR-75-1A, The Asphalt Institute, College Park, MD, May 1975.
18. Evaluation Of Fugitive Dust From Mining, EPA Contract No. 68-02-1321, PEDCo
Environmental, Inc., Cincinnati, OH, June 1976.
19. J. A. Peters and P. K. Chalekode, "Assessment Of Open Sources", Presented at the Third
National Conference On Energy And The Environment, College Corner, OH, October 1,
1975.
20. Illustration of Dryer Drum Hot Mix Asphalt Plant, Pacific Environmental Services, Inc.,
Santa Monica, CA, 1978.
21. Herman H. Forsten, "Applications Of Fabric Filters To Asphalt Plants", presented at the 71st
Annual Meeting of the Air Pollution Control Association, Houston, TX, June 1978.
22. Emission Of Volatile Organic Compounds From Drum Mix Asphalt Plants,
EPA-600/2-81-026, U. S. Environmental Protection Agency, Cincinnati, OH, February 1981.
23. J. S. Kinsey, Asphaltic Concrete Industry - Source Category Report, EPA-600/7-86-038,
U. S. Environmental Protection Agency, Cincinnati, OH, October 1986.
24. Emission Test Report, Mathy Construction Company Plant #6, LaCrosse, Wisconsin,
EMB-No. 91-ASP-ll, Emission Assessment Branch, Office Of Air Quality Planning And
Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC, February
1992.
*
25. Emission Test Report, Mathy Construction Company Plant #26, New Richmond, Wisconsin,
EMB-No. 91-ASP-10, Emission Assessment Branch, Office Of Air Quality Planning And
Standards, U. S. Environmental Protection Agency, Research Triangle Park, NC, April 1992.
26. Source Sampling For Paniculate Emissions, Piedmont Asphalt Paving Company, Gold Hill,
North Carolina, RAMCON Environmental Corporation, Memphis, TN, February 1988.
27. Source Sampling For Paniculate Emissions, Lee Paving Company, Aberdeen, North Carolina,
RAMCON Environmental Corporation, Memphis, TN, September 1989.
28. Stationary Source Sampling Report, S. T. Wooten Company, Drugstore, North Carolina,
Entropy Environmentalists Inc., Research Triangle Park, NC, October 1989.
29. Source Sampling Report For Piedmont Asphalt Paving Company, Gold Hill, North Carolina,
Environmental Testing Inc., Charlotte, NC, October 1988.
1/95 Mineral Products Industry 11.1-19
-------
30. Source Sampling For Paniculate Emissions, Asphalt Paving Of Shelby, Inc., King's Mountain,
North Carolina, RAMCON Environmental Corporation, Memphis, TN, June 1988.
31. Emission Test Report, Western Engineering Company, Lincoln, Nebraska, EMB-83-ASP-5,
Emission Measurement Branch, Office Of Air Quality Planning And Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, September 1984.
32. Source Sampling Report For Smith And Sons Paving Company, Pineola, North Carolina,
Environmental Testing Inc., Charlotte, NC, June 1988.
33. Source Sampling For Particulate Emissions, Superior Paving Company, Statesville, North
Carolina, RAMCON Environmental Corporation, Memphis, TN, June 1988.
34. Report OfAB2588 Air Pollution Source Testing At Industrial Asphalt, Invindale, California,
Engineering-Science, Inc., Pasadena, CA, September 1990.
35. A Comprehensive Emission Inventory Report As Required Under The Air Toxics "Hot Spots "
Information And Assessment Act Of 1987, Calmat Co., Fresno II Facility, Fresno California,
Engineering-Science, Inc., Pasadena, CA, September 1990.
36. Emission Test Report, Sloan Company, Cocoa, Florida, EMB-84-ASP-8, Emission
Measurement Branch, Office Of Air Quality Planning And Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC, November 1984.
37. Emission Test Report, T. J. Campbell Company, Oklahoma City, Oklahoma, EMB-83-ASP-4,
Emission Measurement Branch, Office Of Air Quality Planning And Standards, U. S.
Environmental Protection Agency, Research Triangle Park, NC, May 1984.
38. Characterization Oflnhalable Particulate Matter Emissions From A Drum-mix Asphalt Plant,
Final Report, Industrial Environmental Research Laboratory, U. S. Environmental Protection
Agency, Cincinnati, OH, February 1983.
39. Kathryn O'C. Gunkel, NAPA Stack Emissions Program, Interim Status Report, National
Asphalt Pavement Association, Baltimore, MD, February 1993.
40. Written communication from L. M. Weise, Wisconsin Department Of Natural Resources, to
B. L. Strong, Midwest Research Institute, Cary, NC, May 15, 1992.
41. Stationary Source Sampling Report, Alliance Contracting Corporation, Durham, North
Carolina, Entropy Environmentalists Inc., Research Triangle Park, NC, May 1988.
42. Katherine O'C. Gunkel, Hot Mix Asphalt Mixing Facilities, Wildwood Environmental
Engineering Consultants, Inc., Baltimore, MD, 1992.
43. Written communication from R. Gary Fore, National Asphalt Pavement Association, Lanham,
MD, to Ronald Myers, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 1, 1994.
11.1-20 EMISSION FACTORS 1/95
-------
11.2 Asphalt Roofing
11.2.1 General1"2
The asphalt roofing industry manufactures asphalt-saturated felt rolls, fiberglass and organic
(felt-based) shingles, and surfaced and smooth roll roofing. Most of these products are used in roof
construction, but small quantities are used in walls and other building applications.
11.2.2 Process Description1^
The production of asphalt roofing products consists of six major operations: (1) felt
saturation, (2) coating, (3) mineral surfacing (top and bottom), (4) cooling and drying, (5) product
finishing (seal-down strip application, cutting and trimming, and laminating of laminated shingles),
and (6) packaging. There are six major production support operations: (1) asphalt storage,
(2) asphalt blowing, (3) back surfacing and granule storage, (4) filler storage, (5) filler heating, and
(6) filler and coating asphalt mixing. There are two primary roofing substrates: organic (paper felt)
and fiberglass. Production of roofing products from the two substrates differ mainly in the
elimination of the saturation process when using fiberglass.
Preparation of the asphalt is an integral part of the production of asphalt roofing. This
preparation, called "blowing," involves the oxidation of asphalt flux by bubbling air through liquid
asphalt flux at 260°C (500°F) for 1 to 10 hours. The amount of time depends on the desired
characteristics of the roofing asphalt, such as softening point and penetration rate. Blowing results in
an exothermic reaction that requires cooling. Water sprays are applied either internally or externally
to the shell of the blowing vessel. A typical plant blows four to six batches per 24-hour day.
Blowing may be done in either vertical vessels or in horizontal chambers (both are frequently referred
to as "blowing stills"). Inorganic salts such as ferric chloride (FeCl3) may be used as catalysts to
achieve desired properties and to increase the rate of reaction in the blowing still, decreasing the time
required for each blow. Blowing operations may be located at oil refineries, asphalt processing
plants, or asphalt roofing plants. Figure 11.2-1 illustrates an asphalt blowing operation.
The most basic asphalt roofing product is asphalt-saturated felt. Figure 11.2-2 shows a
typical line for the manufacture of asphalt-saturated felt. It consists of a dry felt feed roll, a dry
looper section, a saturator spray section (seldom used today), a saturator dipping section, heated
drying-in drums, a wet looper, cooling drums, a finish floating looper, and a roll winder.
Organic felt may weigh from approximately 20 to 55 pounds (Ib) per 480 square feet (ft2) (a
common unit in the paper industry), depending upon the intended product. The felt is unrolled from
the unwind stand onto the dry looper, which maintains a constant tension on the material. From the
dry looper, the felt may pass into the spray section of the saturator (not used in all plants), where
asphalt at 205 to 250°C (400 to 480 °F) is sprayed onto one side of the felt through several nozzles.
In the saturator dip section, the saturated felt is drawn over a series of rollers, with the bottom rollers
submerged in hot asphalt at 205 to 250°C (400 to 480°F). During the next step, heated drying-in
drums and the wet looper provide the heat and time, respectively, for the asphalt to penetrate the felt.
The saturated felt then passes through water-cooled rolls onto the finish floating looper, and then is
rolled and cut to product size on the roll winder. Three common weights of asphalt felt are
approximately 12, 15, and 30 Ib per 108 ft2 (108 ft2 of felt covers exactly 100 ft2 of roof).
1/95 Mineral Products Industry 11.2-1
-------
EMISSION SOURCE
ASPHALT BLOWING: SATURANT
ASPHALT BLOWING. COATING
ASPHALT BLOWING: (GENERAL)
FIXED ROOF ASPHALT
STORAGE TANKS
FLOATING ROOF ASPHALT
STORAGE TANKS
sec
3-05-001-01
3-05-001-02
3-05-001-10
3-05-001 -30, -31
3-05-001 -32, -33
KNOCKOUT BOX
OR CYCLONE
AIR, WATER VAPOR, OIL.
VOC's. AND PM
ASPHALT
FLUX
BLOWING
STILL
CONTAINING
ASPHALT
A A A A
TO
AIR. WATER VAPOR, CONTRnl
VOC's. AND PM * DEVICE
RECOVERED OIL
-WATER
AIR
ASPHALT HEATER
~l
VENT TO
CONTROL OR
ATMOSPHERE
AIR BLOWER
BLOWN ASPHALT
VENT TO
ATMOSPHERE
HEATER
ASPHALT FLUX
STORAGE TANK
Figure 11.2-1. Asphalt blowing process flow diagram.1'4
(SCC = Source Classification Code)
11.2-2
EMISSION FACTORS
1/95
-------
EMISSION SOURCE
DIPPING ONLY
SPRAYING ONLY
DIPPING/SPRAYING
DIP SATURATOR, DRYING-IN DRUM. WET LOOPS! AND COATER
DIP SATURATOR, DRYING-IN DRUM, AND COATER
DIP SATURATOR, DRYING-IN DRUM. ANO WET LOOPER
SPRAY/DIP SATURATOR, DRYINQ-IN DRUM, WET LOOPER.
COATER, ANO STORAGE TANKS
ffXED ROOF ASPHALT STORAOE TANKS
FLOATING ROOF ASPHALT STORAGE TANKS
sec
3-05-001-11
3-05-001-12
3-054101-13
3-05-001-18
3^»O01-17
3-05-001-18
3-OS001-19
J05-001-30.-31
3-05401-32, -33
VENT TO CONTROL
EQUIPMENT
t
SATURATOR ENCLOSURE -|
, . FINISH .
FLOATING LOOPER
VENT TO CONTROL EQUIPMENT
OR ATMOSPHERE
BURNER
SATURATOR DIP
SECTION GATES
ROLL WINDER
FOR ASPHALT
FELT
_ ___ __ ___ J
Figure 11.2-2. Asphalt-saturated felt manufacturing process.1'2
(SCC = Source Classification Code)
1/95
Mineral Products Industry
11.2-3
-------
The typical process arrangement for manufacturing asphalt shingles, mineral-surfaced rolls,
and smooth rolls is illustrated in Figure 11.2-3. For organic products, the initial production steps are
similar to the asphalt-saturated felt line. For fiberglass (polyester) products, the initial saturation
operation is eliminated although the dry looper is utilized. A process flow diagram for fiberglass
shingle and roll manufacturing is presented in Figure 11.2-4. After the saturation process, both
organic and fiberglass (polyester) products follow essentially the same production steps, which include
a coater, a granule and sand or backing surface applicator, a press section, water-cooled rollers
and/or water spray cooling, finish floating looper, and a roll winder (for roll products), or a
seal-down applicator and a shingle cutter (for shingles), or a laminating applicator and laminating
operation (for laminated shingles), a shingle stacker, and a packaging station.
Saturated felt (from the saturator) or base fiberglass (polyester) substrate enters the coater.
Filled asphalt coating at 180 to 205 °C (355 to 425 °F) is released through a valve onto the top of the
mat just as it passes into the coater. Squeeze rollers in the coater apply filled coating to the backside
and distribute it evenly to form a thick base coating to which surfacing materials will adhere. Filled
asphalt coating is prepared by mixing coating asphalt or modified asphalt at approximately 250°C
(480°F) and a mineral stabilizer (filler) in approximately equal proportions. Typically, the filler is
dried and preheated at about 120°C (250°F) in a filler heater before mixing with the coating asphalt.
Asphalt modifiers can include rubber polymers or olefin polymers. When modified asphalt is used to
produce fiberglass roll roofing, the process is similar to the process depicted in Figure 11.2-4 with
the following exception: instead of a coater, an impregnation vat is used, and preceding this vat,
asphalt, polymers, and mineral stabilizers are combined in mixing tanks.
After leaving the coater, the coated sheet to be made into shingles or mineral-surfaced rolls
passes through the granule applicator where granules are fed onto the hot, coated surface. The
granules are pressed into the coating as the mat passes around a press roll where it is reversed,
exposing the bottom side. Sand, talc, or mica is applied to the back surface and is also pressed into
the coating.
After application of the mineral surfacing, the mat is cooled rapidly by water-cooled rolls
and/or water sprays and is passed through air pressure-operated press rolls used to embed the
granules firmly into the filled coating. The mat then passes through a drying section where it is air
dried. After drying, a strip of adhesive (normally asphalt) is applied to the roofing surface. The strip
will act to seal the loose edge of the roofing after application to a roof. A finish looper in the line
allows continuous movement of the sheet through the preceding operations and serves to further cool
and dry the roofing sheet. Roll roofing is completed at this point is and moves to a winder where
rolls are formed. Shingles are passed through a cutter, which cuts the sheet into individual shingles.
(Some shingles are formed into laminated products by layering the shingle pieces and binding them
together with a laminating material, normally a modified asphalt. The laminant is applied in narrow
strips to the backside of the sheet.) The finished shingles are stacked and packaged for shipment.
There are several operations that support the asphalt roofing production line. Asphalt (coating
and saturant) is normally delivered to the facility by truck and rail and stored in heated storage tanks.
Filler (finely divided mineral) is delivered by truck and normally is pneumatically conveyed to storage
bins that supply the filler heater. Granules and back surfacing material are brought in by truck or rail
and mechanically or pneumatically conveyed to storage bins.
11.2.3 Emissions And Controls
Emissions from the asphalt roofing industry consist primarily of paniculate matter (PM) and
volatile organic compounds (VOC). Both are emitted from asphalt storage tanks, blowing stills,
11.2-4 EMISSION FACTORS 1/95
-------
EMISSION SOURCE
Far SATURATION- DIPPING ONLY
FELT SATURATION- DIPPING/SPRAYING
DIPPING ONLY
SPRAYING ONLY
DIPPING/SPRAYING
DIP SATURATOR, DRYING-IN DRUM, WET LOOPER AND COATER
DIP SATURATOR. DRYING-IN DRUM, AND COATER
DIP SATURATOR. DRYING-IN DRUM. AND YICT LOOPER
SPRAY/DIP SATURATOR. DRYING-IN DRUM, WET LOOPER,
COATER, AND STORAGE TANKS
FIXED ROOF ASPHALT STORAGE TANKS
FLOATING ROOF ASPHALT STORAGE TANKS
SCC
345-001-03
3-O5-OO1-O4
305-001-11
3-05-OO1-12
105-001-13
3-05-001-16
3-05-001-17
3-05-OO1-18
3-05-001-19
345-001-30.31
105-001-32. -33
l\\\\\\\\\\\\\\
TANK TRUCK
CONTROL CONVEYOR
EQUIPMENT
t
u
USE TANK
STORAGE
TANK
LAM WANT
STORAGE TANK
Figure 11.2-3. Organic shingle and roll manufacturing process flow diagram.1'2
(SCC = Source Classification Code)
1/95
Mineral Products Industry
11.2-5
-------
EMISSION SOURCE
FELT SATURATION: DIPPING ONLY
FELT SATURATION' DIPPING/SPRAYING
DIPPING ONLY
SPRAYING ONLY
DIPPING/SPRAYING
CMP SATURATOR. DRYING-IN DRUM. WET LOOPER. AND COATER
DIP SATURATOR, DRYING-IN DRUM, AND COATER
DIP SATURATOR. DRYING-IN DRUM, AND WET LOOPS!
SPRAY/DP SATURATOR, DRYING-IN DRUM. WET LOOPER.
COATER, AND STORAGE TANKS
FIXED ROOF ASPHALT STORAGE TANKS
FLOATING ROOF ASPHALT STORAGE TANKS
SCO
3-05-001 -03
3-O5-OO1-04
3-05-001-11
3-OS-001-12
345-001-13
3-OS-001-18
3-O5-001-17
3-05-OO1-18
3-05-001-18
3-05-001-30-31
3-O5-001-32, 33
LJ
STORAGE
TANK
LAMINANT
STORAGE TANK
Figure 11.2-4. Fiberglass shingle and roll manufacturing process flow diagram.1*2
(SCC = Source Classification Code)
11.2-6
EMISSION FACTORS
1/95
-------
saturators, coater-mixer tanks, and craters. The PM from these operations is primarily recondensed
asphalt fume. Sealant strip and laminant applicators are also sources of small amounts of PM and
VOCs. Mineral surfacing operations and materials handling are additional sources of PM. Small
amounts of polycyclic organic matter (POM) are also emitted from blowing stills and saturators.
Asphalt and filler heaters are sources of typical products of combustion from natural gas or the fuel in
use.
A common method for controlling emissions from the saturator, including the wet looper, is
to enclose them completely and vent the enclosure to a control device. The coater may be partially
enclosed, normally with a canopy-type hood that is vented to a control device. Full enclosure is not
always practical due to operating constraints. Fugitive emissions from the saturator or coater may
pass through roof vents and other building openings if not captured by enclosures or hoods. Control
devices for saturator/coater emissions include low-voltage electrostatic precipitators (ESP),
high-energy air filters (HEAP), coalescing filters (mist eliminators), afterburners (thermal oxidation),
fabric filters, and wet scrubbers. Blowing operations are controlled by thermal oxidation
(afterburners).
Emission factors for filterable PM from the blowing and saturation processes are summarized
in Tables 11.2-1 and 11.2-2. Emission factors for total organic compounds (TOC) and carbon
monoxide (CO) are shown in Tables 11.2-3 and 11.2-4.
Paniculate matter associated with mineral handling and storage operations is captured by
enclosures, hoods, or pickup pipes and controlled by fabric filtration (baghouses) with removal
efficiencies of approximately 95 to 99 percent. Other control devices that may be used with mineral
handling and storage operations are wet scrubbers and cyclones.
In the industry, closed silos and bins are used for mineral storage, so open storage piles are
not an emission source. To protect the minerals from moisture pickup, all conveyors that are outside
the buildings are covered or enclosed. Fugitive mineral emissions may occur at unloading points
depending on the type of equipment used and the mineral handled. The discharge from the conveyor
to the silos and bins is normally controlled by a fabric filter (baghouse).
1/95 Mineral Products Industry 11.2-7
-------
Table 11.2-1 (Metric Units). EMISSION FACTORS FOR ASPHALT ROOFING8
Process
Filterable
PMb
EMISSION
FACTOR
RATING
Asphalt blowing: saturant asphalt6
(SCC 3-05-001-01)
Asphalt blowing: coating asphaltd
(SCC 3-05-001-02)
Asphalt blowing: saturant asphalt with afterburner6
(SCC 3-05-001-01)
Asphalt blowing: coating asphalt with afterburnerd
(SCC 3-05-001-02)
Shingle saturation: dip saturator, drying-in drum section,
wet looper, and coatere
(SCC 3-05-001-16)
Shingle saturation: dip saturator, drying-in drum section, wet
looper, and coater with ESPf
(SCC 3-05-001-16)
Shingle saturation: dip saturator, drying-in drum section, and
wet looper with HEAFg
(SCC 3-05-001-18)
Shingle saturation: spray/dip saturator, drying-in drum
section, wet looper, coater, and storage tanksh
(SCC 3-05-001-19)
Shingle saturation: spray/dip saturator, drying-in drum
section, wet looper, coater, and storage tanks with HEAFh
(SCC 3-05-001-19)
3.3
12
0.14
0.41
0.60
0.016
0.035
1.6
0.027
E
E
D
D
D
D
D
D
D
a Factors represent uncontrolled emissions unless noted. Emission factors in kg/Mg of shingles
produced unless noted. Polycyclic organic matter emissions comprise approximately 0.03% of
PM for blowing stills and 1.1% of PM for sarurators. SCC = Source Classification Code.
ESP = electrostatic precipitator. HEAP = high-energy air filter.
b As measured using EPA Method 5A. Filterable PM is that PM collected on or prior to the
filter, which is heated to 42.2°C (108°F).
c Reference 10. Saturant blow of 1.5 hours. Expressed as kg/Mg of asphalt processed.
d Reference 10. Coating blow of 4.5 hours. Expressed as kg/Mg of asphalt processed.
e References 6-7,9.
f Reference 6.
g Reference 9.
h Reference 8.
11.2-8
EMISSION FACTORS
1/95
-------
Table 11.2-2 (English Units). EMISSION FACTORS FOR ASPHALT ROOFING"
Process
Filterable
PMb
EMISSION
FACTOR
RATING
Asphalt blowing: saturant asphalt0
(SCC 3-05-001-01)
Asphalt blowing: coating asphalt*1
(SCC 3-05-001-02)
Asphalt blowing: saturant asphalt with afterburner0
(SCC 3-05-001-01)
Asphalt blowing: coating asphalt with afterburnerd
(SCC 3-05-001-02)
Shingle saturation: dip saturator, drying-in drum section, wet
looper, and coater6
(SCC 3-05-001-16)
Shingle saturation: dip saturator, drying-in drum section, wet
looper, and coater with ESPf
(SCC 3-05-001-16)
Shingle saturation: dip saturator, drying-in drum section, and
wet looper with HEAPS
(SCC 3-05-001-18)
Shingle saturation: spray/dip saturator, drying-in drum
section, wet looper, coater, and storage tanksh
(SCC 3-05-001-19)
Shingle saturation: spray/dip saturator, drying-in drum
section, wet looper, coater, and storage tanks with HEAFh
(SCC 3-05-001-19)
6.6
24
0.27
0.81
1.2
0.032
0.071
3.2
0.053
D
D
D
D
D
D
a Factors represent uncontrolled emissions unless noted. Emission factors in Ib/ton of shingles
produced unless noted. Polycyclic organic matter emissions comprise approximately 0.03% of
PM for blowing stills and 1.1% of PM for saturators. SCC = Source Classification Code.
ESP = electrostatic precipitator. HEAP = high-energy air filter.
b As measured using EPA Method 5A. Filterable PM is that PM collected on or prior to the
filter, which is heated to 42.2°C (108°F).
c Reference 10. Saturant blow of 1.5 hours. Expressed as Ib/ton of asphalt processed.
d Reference 10. Coating blow of 4.5 hours. Expressed as Ib/ton of asphalt processed.
e References 6-7,9.
f Reference 6.
g Reference 9.
h Reference 8.
1/95
Mineral Products Industry
11.2-9
-------
Table 11.2-3 (Metric Units). EMISSION FACTORS FOR ASPHALT ROOFING4
Process
Asphalt blowing: saturant asphalt*1
(SCC 3-05-001-01)
Asphalt flowing: coating asphalt11
(SCC 3-05-001-02)
Asphalt blowing: saturant asphalt with
afterburner0
(SCC 3-05-001-01)
Asphalt blowing: coating asphalt with afterburner11
(SCC 3-05-001-02)
Shingle saturation: dip saturator, drying-in drum
section, wet looper, and coaler6
(SCC 3-05-001-16)
Shingle saturation: dip saturator, drying-in drum
section, wet looper, and coaler with ESF^
(SCC 3-05-001-16)
Shingle saturation: dip saturator, drying-in drum
section, and coaler5
(SCC 3-05-001-17)
Shingle saturation: dip saturator, drying-in drum
section, and wet looper with HEAP
(SCC 3-05-001-18)
Shingle saturation: spray/dip saturator, drying-in
drum section, wet looper, coaler, and storage
tanks'
(SCC 3-05-001-19)
Shingle saturation: spray/dip saturator, drying-in
drum section, wet looper, coaler, and storage
tanks with HEAP
(SCC 3-05-001-19)
Asphalt blowing^
(SCC 3-05-001-10)
Asphalt blowing with afterburner*
(SCC 3-05-001-10)
TOCb
0.66
1.7
0.0022
0.085
0.046
0.049
ND
0.047
0.13
0.16
ND
ND
EMISSION
FACTOR
RATING
E
E
D
D
D
D
D
D
D
CO
ND
ND
ND
ND
ND
ND
0.0095
ND
ND
ND
0.14
1.9
EMISSION
FACTOR
RATING
D
E
E
a Factors represent uncontrolled emissions unless otherwise noted. Emission factors in kg/Mg
of shingles produced unless noted. SCC = Source Classification Code. ND = no data.
ESP = electrostatic precipitator. HEAP = high-energy air filter.
b Total organic compounds as measured with an EPA Method 25A (or equivalent) sampling
train.
c Reference 10. Saturant blow of 1.5 hours. Expressed as kg/Mg of asphalt processed.
d Reference 10. Coating blow of 4.5 hours. Expressed as kg/Mg of asphalt processed.
e References 6-7.
f Reference 6.
g Reference 7.
h Reference 9.
J Reference 8.
k Reference 3. Emission factors in kg/Mg of saturated felt produced.
11.2-10
EMISSION FACTORS
1/95
-------
Table 11.2-4 (English Units). EMISSION FACTORS FOR ASPHALT ROOFING3
Process
Asphalt blowing: saturant asphalt0
(SCC 3-05-001-01)
Asphalt blowing: coating asphalt
(SCC 3-05-001-02)
Asphalt blowing: saturant asphalt with
afterburner*1
(SCC 3-05-001-01)
Asphalt blowing: coating asphalt with afterburner11
(SCC 3-05-001-02)
Shingle saturation: dip saturator, drying-in drum
section, wet looper, and coatere
(SCC 3-05-O01-16)
Shingle saturation: dip saturator, drying-in drum
section, wet looper, and coaler with ESP*
(SCC 3-O5-001-16)
Shingle saturation: dip saturator, drying-in drum
section, and coaler8
(SCC 3-05-O01-17)
Shingle saturation: dip saturator, drying-in drum
section, and wet looper with HEAP1*
(SCC 3-05-001-18)
Shingle saturation: spray/dip saturator, drying-in
drum section, wet looper, coaler, and storage
tank^
(SCC 3-05-001-19)
Shingle saturation: spray /dip saturator, drying-in
drum section, wet looper, coaler, and storage
tanks with HEAP"
(SCC 3-O5-001-19)
Asphalt blowing^
(SCC 3-O5-001-10)
Asphalt blowing with afterburner1'
(SCC 3-05-001-10)
TOCb
1.3
3.4
0.0043
0.017
0.091
0.098
ND
0.094
0.26
0.32
ND
ND
EMISSION
FACTOR
RATING
E
E
D
D
D
D
D
D
D
CO
ND
ND
ND
ND
ND
ND
0.0019
ND
ND
ND
0.27
3.7
EMISSION
FACTOR
RATING
D
E
E
a Factors represent uncontrolled emissions unless otherwise noted. Emission factors in Ib/ton of
shingles produced unless noted. SCC = Source Classification Code. ND = no data.
ESP = electrostatic precipitator. HEAP = high-energy air filter.
b Total organic compounds as measured with an EPA Method 25A (or equivalent) sampling
train.
c Reference 10. Saturant blow of 1.5 hours. Expressed as Ib/ton of asphalt processed.
d Reference 10. Coating blow of 4.5 hours. Expressed as Ib/ton of asphalt processed.
e References 6-7.
f Reference 6.
8 Reference 7.
h Reference 9.
J Reference 8.
k Reference 3. Emission factors in Ib/ton of saturated felt produced.
1/95
Mineral Products Industry
11.2-11
-------
References For Section 11.2
1. Written communication from Russel Snyder, Asphalt Roofing Manufacturers Association,
Rockville, MD, to Richard Marinshaw, Midwest Research Institute, Gary, NC, May 2, 1994.
2. J. A. Danielson, Air Pollution Engineering Manual (2nd Ed.), AP-40, U. S. Environmental
Protection Agency, Research Triangle Park, NC, May 1973. Out of print.
3. Atmospheric Emissions from Asphalt Roofing Processes, EPA Contract No. 68-02-1321, Pedco
Environmental, Cincinnati, OH, October 1974.
4. L. W. Corbett, "Manufacture of Petroleum Asphalt," Bituminous Materials: Asphalts, Tars,
and Pitches, 2(1), Interscience Publishers, New York, 1965.
5. Background Information for Proposed Standards Asphalt Roofing Manufacturing Industry,
EPA 450/3-80-02la, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 1980.
6. Air Pollution Emission Test, Celotex Corporation, Fairfield, Alabama, EMB Report
No. 76-ARM-13, U. S. Environmental Protection Agency, Research Triangle Park, NC,
October 1976.
7. Air Pollution Emission Test, Certain-Teed Products, Shahopee, Minnesota, EMB Report
No. 76-ARM-12, U. S. Environmental Protection Agency, Research Triangle Park, NC, May
1977.
8. Air Pollution Emission Test, Celotex Corporation, Los Angeles, California, EMB Report
No. 75-ARM-8, U. S. Environmental Protection Agency, Research Triangle Park, NC,
August 1976.
9. Air Pollution Emission Test, Johns Manville Corporation, Waukegan, Illinois, EMB Report
No. 76-ARM-13, U. S. Environmental Protection Agency, Research Triangle Park, NC,
August 1976.
10. Air Pollution Emission Test, Elk Roofing Company, Stephens, Arkansas, EMB Report
No. 76-ARM-ll, U. S. Environmental Protection Agency, Research Triangle Park; NC, May
1977.
11.2-12 EMISSION FACTORS 1/95
-------
11.3 Brick And Structural Clay Product Manufacturing
11.3.1 General1'2
The brick and structural clay products industry is made up primarily of facilities that manufacture
structural brick from clay, shale, or a combination of the two. These facilities are classified under standard
industrial classification (SIC) code 3251, brick and structural clay tile. Facilities that manufacture structural
clay products, such as clay pipe, adobe brick, chimney pipe, flue liners, drain tiles, roofing tiles, and sewer
tiles are classified under SIC code 3259, structural clay products, not elsewhere classified.
11.3.2 Process Description3"6
The manufacture of brick and structural clay products involves mining, grinding, screening and
blending of the raw materials followed by forming, cutting or shaping, drying, firing, cooling, storage, and
shipping of the final product. A typical brick manufacturing process is shown in Figure 11.3-1.
The raw materials used in the manufacture of brick and structural clay products include surface clays
and shales, which are mined in open pits. The moisture content of the raw materials ranges from a low of
about 3 percent at some plants to a high of about 15 percent at other plants. Some facilities have onsite
mining operations, while others bring in raw material by truck or rail. The raw material is typically loaded by
truck or front-end loader into a primary crusher for initial size reduction. The material is then conveyed to a
grinding room, which houses several grinding mills and banks of screens that produce a fine material that is
suitable for forming brick or other products. Types of grinding mills typically used include dry pan grinders,
roller mills, and hammermills. From the grinding room, the material is conveyed to storage silos or piles,
which typically are enclosed. The material is then either conveyed to the mill room for brick forming or
conveyed to a storage area.
Most brick are formed by the stiff mud extrusion process, although brick are also formed using the
soft mud and dry press processes (there may be no plants in the U.S. currently using the dry press process).
A typical stiff mud extrusion line begins with a pug mill, which mixes the ground material with water and
discharges the mixture into a vacuum chamber. Some facilities mix additives such as barium carbonate,
which prevents sulfates from rising to the surface of the brick, with the raw material prior to extrusion. The
moisture content of the material entering the vacuum chamber is typically between 14 and 18 percent. The
vacuum chamber removes air from the material, which is then continuously augered or extruded through dies.
The resulting continuous "column" is lubricated with oil or other lubricant to reduce friction during extrusion.
If specified, various surface treatments, such as manganese dioxide, iron oxide, and iron chromite can be
applied at this point. These treatments are used to add color or texture to the product. A wire-cutting
machine is used to cut the column into individual bricks, and then the bricks are mechanically or hand set onto
kiln cars. All structural tile and most brick are formed by this process. Prior to stacking, some facilities
mechanically process the unfired bricks to create rounded imperfect edges that give the appearance of older
worn brick.
The soft mud process is usually used with clay that is too wet for stiff mud extrusion. In a pug mill,
the clay is mixed with water to a moisture content of 15 to 28 percent, and the bricks are formed in molds and
are dried before being mechanically stacked onto kiln cars. In the dry press process, clay is mixed with a
small amount of water and formed in steel molds by applying pressure of 500 to 1,500 pounds per square
inch (3.43 to 10.28 megapascals).
8/97 Mineral Products 11.3-1
-------
u
•B.8
I 8
1
ro u
O
oo
11.3-2
EMISSION FACTORS
8/97
-------
Following forming and stacking, the brick-laden kiln cars enter a predryer or a holding area and are
then loaded into the dryer. Dryers typically are heated to about 400°F (204°C) using waste heat from the
cooling zone of the kiln. However, some plants heat dryers with gas or other fuels. Dryers may be in-line or
totally separate from the kiln. From the dryer, the bricks enter the kiln. The most common type of kiln used
for firing brick is the tunnel kiln, although some facilities operate downdraft periodic kilns or other types of
kilns. A typical tunnel kiln ranges from about 340 feet (ft) (104 meters [m]) to 500 ft (152 m) in length and
includes a preheat zone, a firing zone, and a cooling zone. The firing zone typically is maintained at a
maximum temperature of about 2000°F (1090°C). During firing, small amounts of excess fuel are
sometimes introduced to the kiln atmosphere, creating a reducing atmosphere that adds color to the surface of
the bricks. This process is called flashing. After firing, the bricks enter the cooling zone, where they are
cooled to near ambient temperatures before leaving the tunnel kiln. The bricks are then stored and shipped.
A periodic kiln is a permanent brick structure with a number of fireholes through which fuel enters
the furnace. Hot gases from the fuel are first drawn up over the bricks, then down through them by
underground flues, and then out of the kiln to the stack.
In all kilns, firing takes place in six steps: evaporation of free water, dehydration, oxidation,
vitrification, flashing, and cooling. Natural gas is the fuel most commonly used for firing, followed by coal
and sawdust. Some plants have fuel oil available as a backup fuel. Most natural gas-fired plants that have a
backup fuel use vaporized propane as the backup fuel. For most types of brick, the entire drying, firing, and
cooling process takes between 20 and 50 hours.
Flashing is used to impart color to bricks by adding uncombusted fuel (other materials such as zinc,
used tires, or used motor oil are also reportedly used) to the kiln to create a reducing atmosphere. Typically,
flashing takes place in a "flashing zone" that follows the firing zone, and the bricks are rapidly cooled
following flashing. In tunnel kilns, the uncombusted fuel or other material typically is drawn into the firing
zone of the kiln and is burned.
11.3.3 Emissions And Controls3'7-11-22'24'29-30
Emissions from brick manufacturing facilities include particulate matter (PM), PM less than or equal
to 10 microns in aerodynamic diameter (PM-10), PM less than or equal to 2.5 microns in aerodynamic
diameter (PM-2.5) sulfur dioxide (S02), sulfur trioxide (S03), nitrogen oxides (NOX), carbon monoxide
(CO), carbon dioxide (CO2), metals, total organic compounds (TOC) (including methane, ethane, volatile
organic compounds [VOC], and some hazardous air pollutants [HAP]), hydrochloric acid (HC1), and fluoride
compounds. Factors that may affect emissions include raw material composition and moisture content, kiln
fuel type, kiln operating parameters, and plant design. The pollutants emitted from the manufacture of other
structural clay products are expected to be similar to the pollutants emitted from brick manufacturing,
although emissions from the manufacture of glazed products may differ significantly.
The primary sources of PM, PM-10, and PM-2.5 emissions are the raw material grinding and
screening operations and the kilns. Other sources of PM emissions include sawdust dryers used by plants
with sawdust-fired kilns, coal crushing systems used by plants with coal-fired kilns, and fugitive dust sources
such as paved roads, unpaved roads, and storage piles.
Combustion products, including SO2, NOX, CO, and CO2, are emitted from fuel combustion in brick
kilns and some brick dryers. Brick dryers that are heated with waste heat from the kiln cooling zone are not
usually a source of combustion products because kilns are designed to prevent combustion gases from
entering the cooling zone. Some brick dryers have supplemental gas burners that produce small amounts of
NOX, CO, and C02 emissions. These emissions are sensitive to the condition of the burners. The primary
8/97 Mineral Products 11.3-3
-------
source of S02 emissions from most brick kilns is the raw material, which sometimes contain sulfur
compounds. Some facilities use raw material with a high sulfur content, and have higher S02 emissions than
facilities that use low-sulfur raw material. In addition, some facilities use additives that contain sulfates, and
these additives may contribute to S02 emissions. Data are available that indicate that sulfur contents of
surface soils are highly variable, and it is likely that sulfur contents of brick raw materials are also highly
variable.
Organic compounds, including methane, ethane, VOC, and some HAP, are emitted from both brick
dryers and kilns. These compounds also are emitted from sawdust dryers used by facilities that fire sawdust
as the primary kiln fuel. Organic compound emissions from brick dryers may include contributions from the
following sources: (1) petroleum-based or other products in those plants that use petroleum-based or other
lubricants in extrusion, (2) light hydrocarbons within the raw material that vaporize at the temperatures
encountered in the dryer, and (3) incomplete fuel combustion in dryers that use supplemental burners in
addition to waste heat from the kiln cooling zone. Organic compound emissions from kilns are the result of
volatilization of organic matter contained in the raw material and kiln fuel.
Hydrogen fluoride (HF) and other fluoride compounds are emitted from kilns as a result of the
release of the fluorine compounds contained in the raw material. Fluorine typically is present in brick raw
materials in the range of 0.01 to 0.06 percent. As the green bricks reach temperatures of 930° to 1110°F,
(500° to 600 °C), the fluorine in the raw material forms HF and other fluorine compounds. Much of the
fluorine is released as HF. Because fluorine content in clays and shales is highly variable, emissions of HF
and other fluoride compounds vary considerably depending on the raw material used.
A variety of control systems may be used to reduce PM emissions from brick manufacturing
operations. Grinding and screening operations are sometimes controlled by fabric filtration systems, although
many facilities process raw material with a relatively high moisture content (greater than 10 percent) and do
not use add-on control systems. Most tunnel kilns are not equipped with control devices, although fabric
filters or wet scrubbers are sometimes used for PM removal. Paniculate matter emissions from fugitive
sources such as paved roads, unpaved roads, and storage piles can be controlled using wet suppression
techniques.
Gaseous emissions from brick dryers and kilns typically are not controlled using add-on control
devices. However, dry scrubbers that use limestone as a sorption medium may be used to control HF
emissions; control efficiencies of 95 percent or higher have been reported at one plant operating this type of
scrubber. Also, wet scrubbers are used at one facility. These scrubbers, which use a soda ash and water
solution as the scrubbing liquid, provide effective control of HF and SO2 emissions. Test data show that the
only high-efficiency packed tower wet scrubber operating in the U.S. (at brick plants) achieves control
efficiencies greater than 99 percent for SO2 and total fluorides. A unique "medium-efficiency" wet scrubber
operating at the same plant has demonstrated an 82 percent S02 control efficiency.
Process controls are also an effective means of controlling kiln emissions. For example, facilities
with coal-fired kilns typically use a low-sulfur, low-ash coal to minimize SO2 and PM emissions. In addition,
research is being performed on the use of additives (such as lime) to reduce HF and SO2 emissions.
Table 11.3-1 presents emission factors for filterable PM, filterable PM-10, condensible inorganic
PM, and condensible organic PM emissions from brick and structural clay product manufacturing operations.
Two emission factors for uncontrolled grinding and screening operations are presented; one for operations
processing relatively dry material (about 4 percent moisture) and the other for operations processing wet
material (about 13 percent moisture). Table 11.3-2 presents total PM, total PM-10, and total PM-2.5
emission factors for brick and structural clay product manufacturing. Table 11.3-3 presents emission factors
11.3-4 EMISSION FACTORS 8/97
-------
for S02, S03, NOX, CO, and C02 emissions from brick dryers, kilns (fired with natural gas, coal, and
sawdust), and from a combined source—sawdust-fired kiln and sawdust dryer. To estimate emissions of NOX,
and CO from fuel oil-fired kilns, refer to the AP-42 section addressing oil combustion. Table 11.3-4 presents
emission factors for HF, total fluorides, and HC1 emissions from brick kilns and from a combined source--
sawdust-fired kilns and sawdust drying. Table 11.3-5 presents emission factors for TOC as propane,
methane, and VOC from brick dryers, kilns, and from a combined source—sawdust-fired kilns and sawdust
drying. Tables 11.3-6 and 11.3-7 present emission factors for speciated organic compounds and metals,
respectively. Table 11.3-8 presents particle size distribution data for sawdust- and coal-fired kilns. Although
many of the emission factors presented in the tables are assigned lower ratings than emission factors in
previous editions of AP-42, the new factors are based on higher quality data than the old factors.
8/97 Mineral Products 11.3-5
-------
M
00
§
r1
NG OPERA1
S
s
o
1
o
2
QQ
.^
0
PL,
>N FACTOR;
<^
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w
g
u
H
J
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ex
i
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Condensi
1
s
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EMISSION
FACTOR
RATING
I
§
k— f
S5 H S
on o f-'
S
w>
fS
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PL,
EMISSION
FACTOR
RATING
o
i
s ^ ^
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W CJ H
Sfc
2
u
1
C/3
^
^
-
$
s
„
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8
d
2
g
H.
S
1 Primary crusher with fabric
(SCC 3-05-003-40)
3333
3333
3333
33S3
^ 0! ^ ^
§A M
g g
w w w w
m . i Q
P oo o Z
0 d
I ^
Grinding and screening oper
(SCC 3-05-003-02)
processing wet material
processing dry material"
with fabric filter8
Extrusion line with fabric fil
(SCC 3-05-003-42)
1 o
d
W Q
«34 O«
— 00
d d
3 3
§A
g
^ W
Q oo
^ d
W O
"P- |>
0 0
Brick dryer
(SCC 3-05-003-50, -51)
Natural gas-fired kiln
(SCC 3-05-003-11)
Q
o"
d
Q
a
oo
d
Q
00
-------
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§ c S o, S
03
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Reference 2
References
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mtrol condensible PM emissions. Therefore, the uncontrolled Condensible PM emission factors an
°*j
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References :
IH a> <- 3
8/97
Mineral Products
11.3.-7
-------
Table 11.3-2. EMISSION FACTORS FOR TOTAL PM, TOTAL PM-10, AND TOTAL PM-2.5
FROM BRICK MANUFACTURING OPERATIONS3
Source
Primary crusher with fabric filter
(SCC 3-05-003-40)
Grinding and screening operations
(SCC 3-05-003-02)
processing dry material0
processing wet material*1
with fabric filter6
Extrusion line with fabric filte/
(SCC 3-05-003-42)
Natural gas-fired kiln
(SCC 3-05-003-11)
Coal-fired kiln
(SCC 3-05-003-1 3)
uncontrolled
with fabric filter
Sawdust-fired kiln
(SCC 3-05-003-10)
Sawdust-fired kiln and sawdust dryer8
(SCC 3-05-003-61)
Total PM6
PM
ND
8.5
0.025
0.0062
ND
0.96
1.8
0.63
0.93
1.4
EMISSION
FACTOR
RATING
NA
E
E
E
NA
D
B
E
D
E
PM-10
0.00059
0.53
0.0023
0.0032
0.0036
0.87
1.4
ND
0.85
0.31
EMISSION
FACTOR
RATING
E
E
E
E
E
D
C
NA
D
E
PM-2.5
ND
ND
ND
ND
ND
ND
0.87
ND
0.75
ND
EMISSION
FACTOR
RATING
NA
NA
NA
NA
NA
NA
D
NA
D
NA
a Emission factor units are Ib of pollutant per ton of fired bricks produced unless noted. Factors represent
uncontrolled emissions unless noted. SCC = Source Classification Code. ND = no data. NA = not
applicable. To convert from Ib/ton to kg/Mg, multiply by 0.5.
b Total PM emission factors are the sum of filterable PM and condensible inorganic and organic PM
emission factors from Table 11.3-1. Total PM-10 emission factors are the sum of filterable PM-10 and
condensible inorganic and organic PM emission factors from Table 11.3-1. Total PM-2.5 emission factors
are the sum of filterable PM-2.5 and condensible inorganic and organic PM emission factors from Table
11.3-1.
c Emission factor units are Ib of pollutant per ton of raw material processed. Grinding and screening
operations are typically housed in large buildings that can be fully or partially enclosed. Factor is based on
measurements at the inlet to a fabric filter and does not take into account the effect of the building
enclosure. Based on a raw material moisture content of 4 percent.
d Emission factor units are Ib of pollutant per ton of raw material processed. Based on a raw material
moisture content of 13 percent. Grinding and screening operations are typically housed in large buildings
that can be fully or partially enclosed.
e Emission factor units are Ib of pollutant per ton of raw material processed. Grinding and screening
operations are typically housed in large buildings that can be fully or partially enclosed.
f This emission factor is not applicable to typical extrusion lines. Extrusion line with several conveyor drop
points processing material with a 5-9 percent moisture content.
8 Sawdust dryer heated with the exhaust stream from a sawdust-fired kiln.
11.3-8
EMISSION FACTORS
8/97
-------
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t-S -a S S
^ -n S i
!S |t3
!|i|^
! « 11 I
Si
s s
P
(N 00
"Si 5
c/) •"
a s
.2 a
8/97
Mineral Products
11.3.-9
-------
3
O
en
en
H
References
S I 8 § S
££ !<$£
-------
Table 11.3-4. EMISSION FACTORS FOR HYDROGEN FLUORIDE, TOTAL FLUORIDES, AND
HYDROGEN CHLORIDE FROM BRICK MANUFACTURING OPERATIONS'1
Source
Sawdust- or natural gas-fired tunnel kiln
(SCC 3-05-003-10,-! 1)
uncontrolled
with dry scrubber11
with medium-efficiency wet scrubber1
with high-efficiency packed-bed
scrubber*4
Coal-fired tunnel kiln"1
(SCC 3-05-003- 13)
Sawdust-fired kiln and sawdust dryer11
(SCC 3-05-003-61)
HFb
0.37e
ND
ND
ND
0.17
0.18
EMISSION
FACTOR
RATING
C
NA
NA
NA
D
E
Total
fluorides0
0.59f
0.028
0.18
0.0013
ND
ND
EMISSION
FACTOR
RATING
E
C
C
C
NA
NA
HCld
0.178
ND
ND
ND
ND
ND
EMISSION
FACTOR
RATING
D
NA
NA
NA
NA
NA
Emission factor units are Ib of pollutant per ton of fired product. Factors represent uncontrolled emissions
unless noted. To convert from Ib/ton to kg/Mg, multiply by 0.5. SCC = Source Classification Code. ND
= no data. NA = not applicable.
Hydrogen fluoride measured using an EPA Method 26A or equivalent sampling train.
Total fluorides measured using an EPA Method 13B or equivalent sampling train.
Hydrogen chloride measured using an EPA Method 26A or equivalent sampling train.
References 8,11,26-27,32,34. Factor includes data from kilns firing structural clay tile. Data from kilns
firing natural gas and sawdust are averaged together because fuel type (except for coal) does not appear to
affect HF emissions. However, the raw material fluoride content does effect HF emissions. A mass
balance on fluoride will provide a better estimate of emissions for individual facilities. Assuming that all
of the fluorine in the raw material is released as HF, each Ib of fluorine will result in 1.05 Ib of HF
emissions.
Reference 26. Factor is 1.6 times the HF factor.
References 8,26.
References 22,33-34. Kiln firing material with a high fluorine content. Dry scrubber using limestone as a
sorption medium.
Reference 29. Medium-efficiency wet scrubber using a soda-ash/water solution (maintained at pH 7) as
the scrubbing liquid. The design of this scrubber is not typical. Kiln firing material with a high fluorine
content.
Reference 30. High-efficiency packed bed scrubber with soda-ash/water solution circulated through the
packing section. Kiln firing material with a high fluorine content (uncontrolled emission factor of
2. lib/ton).
References 9,26.
Reference 11. Sawdust dryer heated with the exhaust stream from a sawdust-fired kiln.
8/97
Mineral Products
11.3-11
-------
Table 11.3-5. EMISSION FACTORS FOR TOC, METHANE, AND VOC
FROM BRICK MANUFACTURING OPERATIONS'1
Source
Brick dryer11
(SCC 3-05-003-50)
Brick dryer w/supplemental gas burner
(SCC 3-05-003-51)
Brick kiln"
(SCC3-05-003-10,-11,-13)
Sawdust-fired kiln and sawdust dryer"
(SCC 3-05-003-61)
TOCb
0.05e
0.148
0.062k
0.18
EMISSION
FACTOR
RATING
E
E
C
E
Methane
0.02f
0.1 lh
0.037m
ND
EMISSION
FACTOR
RATING
E
E
E
NA
vocc
0.03
0.03
0.024
0.18
EMISSION
FACTOR
RATING
E
E
D
E
a Emission factor units are Ib of pollutant per ton of fired product. Factors represent uncontrolled emissions
unless noted. To convert from Ib/ton to kg/Mg, multiply by 0.5. SCC = Source Classification Code. ND
= no data. ND = not applicable.
b Total organic compounds reported "as propane"; measured using EPA Method 25A, unless noted.
c VOC as propane; calculated as the difference in the TOC and methane emission factors for this source. If
no methane factor is available, VOC emissions are estimated using the TOC emission factor. In addition,
emissions of the non-reactive compounds shown in Table 11.3-6 (brick kiln = 0.00094 Ib/ton) are
subtracted from the TOC factors to calculate VOC.
d Brick dryer heated with waste heat from the kiln cooling zone.
6 References 9-10.
f Reference 9. Methane value includes methane and ethane emissions. Most of these emissions are believed
to be methane.
8 References 8,37.
h Factor is estimated by assuming that VOC emissions from dryers with and without supplemental burners
are equal. The VOC factor is subtracted from the TOC factor to estimate methane emissions.
J Includes natural gas-, coal-, and sawdust-fired tunnel kilns.
k References 8-11,25,32,36-37. Data from kirns firing natural gas, coal, and sawdust are averaged together
because the data indicate that the fuel type does not effect TOC emissions.
m References 8-9,25. Data from kilns firing natural gas, coal, and sawdust are averaged together because the
data indicate that the fuel type does not effect methane emissions.
n Reference 11. Sawdust dryer heated with the exhaust stream from a sawdust-fired kiln.
11.3-12
EMISSION FACTORS
8/97
-------
Table 11.3-6. EMISSION FACTORS FOR ORGANIC POLLUTANT EMISSIONS FROM
BRICK MANUFACTURING OPERATIONS3
EMISSION FACTOR RATING: E
Source
Coal-fired kiln
(SCC 3-05-003- 13)
Pollutant
CASRN
75-34-3
71-55-6
106-46-7
78-93-3
591-78-6
91-57-6
95-48-7
67-64-1
71-43-2
65-85-0
117-81-7
74-83-9
85-68-7
75-15-0
56-23-5
108-90-7
75-00-3
67-66-3
74-87-3
132-64-9
84-66-2
131-11-3
100-41-4
78-59-1
1330-20-7
75-09-2
91-20-3
95-47-6
108-95-2
100-42-5
127-18-4
71-55-6
108-88-3
108-05-4
75-69-4
Name
1,1-dichloroethane
1,1,1 -trichloroethaneb *
1 ,4-dichlorobenzene
2-butanone
2-hexanoneb
2-methylnaphthalene
2-methylphenolb
Acetone*
Benzene
Benzoic acid
Bis(2-ethylhexy)phthalate
Bromomethane
Butylbenzylphthalate
Carbon disulfide
Carbon tetrachlorideb
Chlorobenzene
Chloroethane
Chloroformb
Chloromethane
Dibenzofuran0
Di-n-octylphthalate
Diethylphthalate
Dimethylphthalateb
Ethylbenzene
Isophorone
M-/p-xylene
Methylene chloride*
Naphthalene
O-xylene
Phenol
Styreneb
Tetrachloroethane
Trichloroethane *
Toluene
Vinyl acetate
Trichlorofluoromethane*
Emission Factor,
Ib/ton
5.0xlO'6
BDL(1.7xlO'5)
3.2xlO'6
2.5xlO'4
BDL (9.4x1 0'7)
1.7X10-6
BDL(2.2xlO-6)
6.8X10"4
2.9xlO'4
2.5xlO'4
7.3xlO'5
2.4xlO'5
1.2xlO'6
2.3xlO'6
BDL(1.0xlO'7)
2.1xlO'5
l.lxKT5
BDLCl.OxlO'7)
l.lxlO'4
3.6xlO'7
1.2xlO'5
1.4xlO'6
BDL(7.8xlO'7)
2.1X10'5
3.0xlO'5
1.3xlQ-4
S.OxlO"7
6.9X10'6
4.7xlO'5
3.5xlQ-5
BDL(1.0xlO'7)
BDLO.OxlO'7)
BDL(1.0xlO'7)
2.5X10"4
BDL(1.0xlO'7)
1.4xlO'5
Ref. No.
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
8/97
Mineral Products
11.3-13
-------
Table 11.3-6 (cont.).
Source
Natural gas-fired kiln
(SCC 3-05-003- 11)
Sawdust-fired kiln
(SCC 3-05-003-10)
Pollutant
CASRN
71-55-6
106-46-7
91-57-6
78-93-3
591-78-6
67-64-1
71-43-2
117-81-7
85-68-7
75-15-0
7782-50-5
75-00-3
74-87-3
84-74-2
84-66-2
100-41-4
1330-20-7
74-88-4
91-20-3
95-47-6
108-95-2
100-42-5
127-18-4
108-88-3
71-55-6
78-93-3
591-78-6
95-48-7
67-64-1
107-13-1
71-43-2
117-81-7
74-83-9
75-15-0
56-23-5
67-66-3
74-87-3
84-74-2
132-64-9
Name
1,1,1-Trichloroethane*
1 ,4-dichlorobenzene
2-methylnaphthalene
2-butanone
2-Hexanone
Acetone*
Benzene
Bis(2-ethylhexy)phthalate
Butylbenzylphthalate
Carbon disulfide
Chlorine
Chloroethane
Chloromethane
Di-n-butylphthalate
Diethylphthalate
Ethylbenzene
M-/p-Xylene
lodomethane
Naphthalene
o-Xylene
Phenol
Styrene
Tetrachloroethene
Toluene
l,l,l-trichloroethaneb*
2-butanoneb
2-hexanoneb
2-methylphenolb
Acetone*
Acrylonitrile0
Benzene
Bis(2-ethylhexy)phthalate
Bromomethane
Carbon disulfide
Carbon tetrachlorideb
Chloroform1"
Chloromethane
Di-n-butylphthalatec
Dibenzofuran
Emission Factor,
Ib/ton
4.7X10"6
4.8xlO"5
5.7xlO'5
0.00022
8.5xlO'5
0.0017
0.0029
0.0020
l.SxlO'5
4.3xlO'5
0.0013
0.00057
0.00067
0.00014
0.00024
4.4xWs
6.7xlO'5
9.3xlO'5
6.5xW5
5.8xlO'5
8.6xlO'5
2.0xlO'5
2.8x10-*
0.00016
BDL (3.0xlO'7)
BDL (6.6X10"6)
BDL (3.0xlO'7)
BDL (2.0xlO'9)
3.9x10-*
l.SxlO'5
5.2X10"4
2.9xW5
S.OxlO'5
1.6xlO's
BDL (3.0xlO'7)
BDL (3.0xlO-7)
6.8X10"4
6.1xlO'6
l.SxlO'5
Ref.No.
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11.3-14
EMISSION FACTORS
8/97
-------
Table 11.3-6 (cont).
Source
Sawdust-fired kiln
(SCC 3-05-003- 10)
Sawdust-fired kiln
and sawdust dryer
(SCC 3-05-003-61)
Pollutant
CASRN
84-74-2
100-41-4
74-88-4
1330-20-7
75-09-2
91-20-3
95-47-6
108-95-2
100-42-5
127-18-4
108-88-3
71-55-6
75-69-4
108-05-4
71-55-6
78-93-3
591-78-6
95-48-7
67-64-1
107-13-1
71-43-2
117-81-7
74-83-9
75-15-0
56-23-5
67-66-3
74-87-3
84-74-2
132-64-9
131-11-3
100-41-4
74-88-4
1330-20-7
75-09-2
91-20-3
95-47-6
108-95-2
100-42-5
127-18-4
Name
Dimethylphthalate0
Ethylbenzene
lodomethane
M-/p-xylene
Methylene chloride*
Naphthalene0
O-xylene0
Phenol
Styreneb
Tetrachloroethane
Toluene
Trichloroethaneb*
Trichlorofluoromethane*
Vinyl acetateb
1,1 ,l-trichloroethaneb*
2-butanone
2-hexanone
2-methylphenolb
Acetone*
Acrylonitrile
Benzene
Bis(2-ethylhexy)phthalate
Bromomethane
Carbon disulfide
Carbon tetrachlorideb
Chloroformb
Chloromethane
Di-n-butylphthalate
Dibenzofuran
Dimethylphthalateb
Ethylbenzene
lodomethane
M-/p-xylene
Methylene chloride*
Naphthalene*5
O-xylene
Phenol
Styreneb
Tetrachloroethaneb
Emission Factor,
Ib/ton
l.OxlO'5
8.5xlO'6
2.0X10"4
2.9xlO'5
7.5xlO'6
3.4X10"4
3.8xlO'6
7.2xlO'5
BDL(4.4xlO'7)
BDL (3.0xlO'7)
l.lxlO"4
BDL(3.0xlO'7)
5.8xlO'6
BDL (3.0xlO'7)
BDL (5.2xlO'7)
2.2xlO'4
BDL(3.8xlO'7)
BDL(2.4xlO'9)
0.0010
1.9xlO'5
5.6xlO'4
1.4xlO'4
4.4xlO'5
l.SxlO'5
BDL (3.8xlO-7)
BDL(3.8xlO'7)
0.0014
1.6xlO-5
BDL(2.4xlO'9)
BDL(2.4xlQ-9)
l.OxlO'5
2.4xlO'4
2.9xlO'5
6.2xlO'5
BDL(2.4xlO'9)
7.3xlO'6
l.OxlO'4
BDL(4.2xlQ-6)
BDL(3.8xlO'7)
Ref. No.
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
8/97
Mineral Products
11.3-15
-------
Table 11.3-6 (cont).
Source
Sawdust-fired kiln and
sawdust dryer
(SCC 3-05-003-61)
Pollutant
CASRN
108-88-3
71-55-6
75-69-4
108-05-4
Name
Toluene
Trichloroethaneb*
Trichlorofluoromethane*
Vinyl acetate
Emission Factor,
Ib/ton
4.3xlO'4
BDL (3.8xlO'7)
l.OxlQ-6
1.9xlO'7
Ref.No.
11
11
11
11
Emission factor units are Ib of pollutant per ton of fired bricks produced. To convert from Ib/ton to
kg/Mg, multiply by 0.5. CASRN = Chemical Abstracts Service Registry Number. * = Non-reactive
compound as designated in 40 CFR 51.100(s), July 1, 1995. BDL = concentration was below the method
detection limit.
The emission factor for this pollutant is shown in parentheses and is based on the detection limit.
Emissions were below the detection limit during two of three test runs. Emission factor is estimated as the
average of the single measured quantity and one-half of the detection limit for the two nondetect runs.
These emission factors are based on data from an atypical facility.
Sawdust dryer heated with the exhaust stream from a sawdust-fired kiln.
11.3-16
EMISSION FACTORS
8/97
-------
Table 11.3-7. EMISSION FACTORS FOR METALS EMISSIONS
FROM BRICK MANUFACTURING OPERATIONS8
Source
Kilnb (SCC 3-05-003-10,-! 1,-13)
Coal-fired kiln (SCC 3-05-003-13)
Natural gas-fired kiln (SCC 3-05-003-1 1)
Sawdust-fired kiln (SCC 3-05-003-10)
Sawdust-fired kiln and sawdust dryer*1
(SCC 3-05-003-61)
Pollutant
Antimony
Cadmium
Chromium
Cobalt
Lead
Nickel
Selenium
Arsenic
Beryllium
Manganese
Mercury
Phosphorus
Arsenic
Beryllium
Manganese
Mercury
Arsenic
Beryllium
Manganese
Mercury
Phosphorus
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Lead
Manganese
Mercury
Nickel
Phosphorus
Selenium
Emission Factor,
Ib/ton
2.7xlO'5
1.5xlO"5
5.1xlO'5
2.1X10"6
1.5x10^
7.2xlO'5
2.3X10"4
UxlO"4
1.6xlO'5
2.9X10"4
9.6xlO'5
9.8x10^
3.1xlO'5
4.2x1 0'7
2.9x1 0"4
7.5xlO'6
3.1xlO-5
4.2x!0-7
0.013C
7.5X10-6
9.8X10-4
2.8x!0'6
2.1xlO-5
3.1xlO-7
2.2x1 0'5
4.8xlO'5
1.2X1Q-4
4.8X10-4
l.lxlO'5
3.4xlO'5
5.5X10-4
4.7xlO'5
EMISSION
FACTOR
RATING
D
D
D
E
D
D
D
E
E
D
E
E
D
D
D
D
D
D
E
D
E
E
E
E
E
E
E
E
E
E
E
E
Reference
Nos.
8-9,11,25
8-9,11,25
9,11,25
25
8-9,11,25
9,11,25
8-9,11,25
9
9
8-9,25
9
9,11
8,11,25
8,11,25
8-9,25
11,25
8,11,25
8,11,25
11
11,25
9,11
11
11
11
11
11
11
11
11
11
11
11
a Emission factor units are Ib of pollutant per ton of fired brick produced. Emission factors for individual
facilities will vary based on the metal content of the raw material, metallic colorants used on the face of the
bricks, metallic additives mixed into the bodies of the bricks, and the metal content of the fuels used for
firing the kilns.
b Coal-, natural gas-, or sawdust-fired tunnel kiln.
0 The facility uses a manganese surface treatment on the bricks. The manganese emission factor for coal-
and natural gas-fired kilns is a better estimate for sawdust-fired kilns firing bricks that do not have a
manganese surface treatment. Conversely, this emission factor should be used to estimate manganese
emissions from coal- or natural gas-fired kilns firing a product with manganese surface treatment.
d Sawdust dryer heated with the exhaust stream from a sawdust-fired kiln.
8/97
Mineral Products
11.3-17
-------
Table 11.3.8. AVERAGE PARTICLE SIZE DISTRIBUTION
FOR FILTERABLE PM EMISSIONS FROM KILNS3
Source
Sawdust-fired kiln
Coal-fired kiln
Aerodynamic Diameter,
microns
10b
2.5
1
10b
2.5
1
Percent of Filterable PM
Emissions Less Than or Equal
to Stated Particle Size
75
48
44
63
23
9.8
Reference No.
11,20
11,20
11,20
9,21
21
21
a Particle size distribution based on cascade impactor tests unless noted.
b Based on cascade impactor particle size distribution and a comparison of PM-10 (measured using EPA
Method 201A) and filterable PM (measured using EPA Method 5) emissions.
REFERENCES FOR SECTION 11.3
1. 1992 Census Of Manufactures, Cement And Structural Clay Products, U. S. Department Of
Commerce, Washington, D.C., 1995.
2. Telephone communication between B. Shrager, Midwest Research Institute, Gary, NC, and
N, Cooney, Brick Institute Of America, Reston, VA, October, 20,1994.
3. Compilation Of Air Pollutant Emission Factors, U. S. Environmental Protection Agency, Research
Triangle Park, NC, October 1986.
4. Written communication from J. Dowdle, Pine Hall Brick Co., Inc., Madison, NC, to R. Myers, U. S.
Environmental Protection Agency, Research Triangle Park, NC, September 1992.
5. Written communication from B. Shrager, Midwest Research Institute, Gary, NC, to R. Myers, U. S.
Environmental Protection Agency, Research Triangle Park, NC, April 1993.
6. Written communication from B. Shrager, Midwest Research Institute, Gary, NC, to R. Myers, U. S.
Environmental Protection Agency, Research Triangle Park, NC, September 1993.
7. D. A. Brosnan, "Monitoring For Hydrogen Fluoride Emissions", Ceramic Industry, July 1994.
8. Emission Testing At A Structural Brick Manufacturing Plant-Final Emission Test Report For
Testing At Belden Brick Company, Plant 6, Sugarcreek, OH, U. S. Environmental Protection
Agency, Research Triangle Park, NC, February 1995.
9. Final Test Report For U. S. EPA Test Program Conducted At General Shale Brick Plant, Johnson
City, TN, U. S. Environmental Protection Agency, Research Triangle Park, NC, December 1993.
10. Flue Gas Characterization Studies Conducted On The SOB Kiln And Dryer Stacks In Atlanta, GA
For General Shale Corporation, Guardian Systems, Inc., Leeds, AL, March 1993.
11.3-18
EMISSION FACTORS
8/97
-------
11. Final Test Report For U. S. EPA Test Program Conducted A t Pine Hall Brick Plant, Madison, NC,
U. S. Environmental Protection Agency, Research Triangle Park, NC, August 1993.
12. Source Emission TestAtBelden Brick, Inc., Sugarcreek, OH, No. 1 Kiln, Plants, CSA Company,
Alliance, OH, March 3, 1992.
13. Mass Emission Tests Conducted On The Tunnel Kiln #6B And #28 In Marion, VA, For General
Shale Products Corporation, Guardian Systems, Inc., Leeds, AL, October 1990.
14. Mass Emission Tests Conducted On The Tunnel Kiln #21 In Glascow, VA, For General Shale
Products Corporation, Guardian Systems, Inc., Leeds, AL, October 16, 1990.
15. Source Emission TestAtBelden Brick, Inc., Sugarcreek, OH, No. 1 Kiln, Plant 3, CSA Company,
Alliance, OH, July 21,1989.
16. SuJfur Dioxide Emission Tests Conducted On The #20 Tunnel Kiln In Mooresville, IN, For
General Shale Products Corporation, Guardian Systems, Inc., Leeds, AL, December 2, 1986.
17. Mass Emission Tests Conducted On The #7B Tunnel Kiln In Knoxville, TN, For General Shale
Products Corporation, Guardian Systems, Inc., Leeds, AL, April 22, 1986.
18. Mass Emission Tests Conducted On Plant #15 In Kingsport, TN, For General Shale Products
Corporation, Guardian Systems, Inc., Leeds, AL, October 11, 1983.
19. Particulate Emission Tests For General Shale Products Corporation, Kingsport, TN, Tunnel Kiln
TK-29And Coal Crusher, Guardian Systems, Inc., Leeds, AL, July 21,1982.
20. Building Brick And Structural Clay Wood Fired Brick Kiln, Emission Test Report, Chatham Brick
And Tile Company, Gulf, NC, EMB Report 80-BRK-5, U. S. Environmental Protection Agency,
Research Triangle Park, NC, October 1980.
21. Building Brick And Structural Clay Industry, Emission Test Report, Lee Brick And Tile Company,
Sanford, NC, EMB Report 80-BRK-l, U. S. Environmental Protection Agency, Research Triangle
Park, NC, April 1980.
22. Exhaust Emission Sampling, Acme Brick Company, Sealy, TX, Armstrong Environmental Inc.,
Dallas, TX, June 21, 1991.
23. Stationary Source Sampling Report: Chatham Brick And Tile Company, Sanford, NC, Kiln No. 2
Particulate Emissions Compliance Testing, Entropy Environmentalists, Inc., Research Triangle
Park, NC, July 1979.
24. D. Brosnan, "Technology And Regulatory Consequences Of Fluorine Emissions In Ceramic
Manufacturing", American Ceramic Industry Bulletin, 71 (12), pp 1798-1802, The American
Ceramic Society, Westerville, OH, December 1992.
8/97 Mineral Products 11.3-19
-------
25. Stationary Source Sampling Report Reference No. 14448, Triangle Brick, Merry Oaks, North
Carolina, Emissions Testing For: Carbon Monoxide, Condensible Particulate, Metals, Methane,
Nitrogen Oxides, Particulate, Particulate < 10 Microns, Sulfur Dioxide, Total Hydrocarbons,
Entropy, Inc., Research Triangle Park, NC, October, 1995.
26. B1A HF Research Program Stack Testing Results (and Individual Stack Test Data Sheets), Center
for Engineering Ceramic Manufacturing, Clemson University, Anderson, SC, November, 1995.
27. Source Emission Tests At Stark Ceramics, Inc., East Canton, OH, No. 3 Kiln Stack, CSA
Company, Alliance, OH, September 16,1993.
28. Crescent Brick Stack Test-No. 2 Tunnel Kiln, CSA Company, Alliance, OH, February 29,1988.
29. Emissions Survey Conducted At Interstate Brick Company, Located In West Jordan, Utah,
American Environmental Testing, Inc., Spanish Fork, UT, December 22, 1994.
30. Emissions Survey For SO2, NO^ CO, HF, And PM-10 Emissions Conducted On Interstate Brick
Company's Kiln No. 3 Scrubber, Located In West Jordan, Utah, American Environmental Testing,
Inc., Spanish Fork, UT, November 30,1995.
31. Stationary Source Sampling Report For Isenhour Brick Company, Salisbury, North Carolina, No.
6 Kiln Exhausts 1 And 2, Sawdust Dryer Exhaust, Trigon Engineering Consultants, Inc., Charlotte,
NC, October 1995.
32. Particulate, Fluoride, And CEM Emissions Testing On The #1 And #2 Kiln Exhausts, Boral
Bricks, Inc., Smyrna, Georgia, Analytical Testing Consultants, Inc., Roswell, GA, September 26,
1996.
33. Source Emissions Survey Of Boral Bricks, Inc., Absorber Stack (EPN-K), Henderson, Texas, TACB
Permit 21012, METCO Environmental, Addison, TX, June 1995.
34. Source Emissions Survey Of Boral Bricks, Inc., Absorber Stack (EPN-K) And Absorber Inlet Duct,
Henderson, Texas, METCO Environmental, Addison, TX, February 1996.
35. Stationary Source Sampling Report For Statesville Brick Company, Statesville, NC, Kiln Exhaust,
Sawdust Dryer Exhaust, Trigon Engineering Consultants, Inc., Charlotte, NC, November 1994.
36. Source Emissions Testing, Marseilles Brick, Marseilles, Illinois, Fugro Midwest, Inc., St Ann,
MO, October 13,1994.
37. Source Emissions Testing, Marseilles Brick, Marseilles, Illinois, Fugro Midwest, Inc., St. Ann,
MO, July 1, 1994.
38. Emission Factor Documentation for AP-42 Section 11.3, Brick and Structural Clay Product
Manufacturing, Final Report, Midwest Research Institute, Gary, NC, August 1997.
11.3-20 EMISSION FACTORS 8/97
-------
11.4 Calcium Carbide Manufacturing
11.4.1 General
Calcium carbide (CaC2) is manufactured by heating a lime and carbon mixture to 2000 to
2100°C (3632 to 3812CF) in an electric arc furnace. At those temperatures, the lime is reduced by
carbon to calcium carbide and carbon monoxide (CO), according to the following reaction:
CaO + 3C -» CaC2 + CO
Lime for the reaction is usually made by calcining limestone in a kiln at the plant site. The sources
of carbon for the reaction are petroleum coke, metallurgical coke, and anthracite coal. Because
impurities in the furnace charge remain in the calcium carbide product, the lime should contain no
more than 0.5 percent each of magnesium oxide, aluminum oxide, and iron oxide, and 0.004 percent
phosphorus. Also, the coke charge should be low in ash and sulfur. Analyses indicate that 0.2 to
1.0 percent ash and 5 to 6 percent sulfur are typical in petroleum coke. About 991 kilograms (kg)
(2,185 pounds [lb]) of lime, 683 kg (1,506 Ib) of coke, and 17 to 20 kg (37 to 44 Ib) of electrode
paste are required to produce 1 megagram (Mg) (2,205 lb) of calcium carbide.
The process for manufacturing calcium carbide is illustrated in Figure 11.4-1. Moisture is
removed from coke in a coke dryer, while limestone is converted to lime in a lime kiln. Fines from
coke drying and lime operations are removed and may be recycled. The two charge materials are
then conveyed to an electric arc furnace, the primary piece of equipment used to produce calcium
carbide. There are three basic types of electric arc furnaces: the open furnace, in which the CO
burns to carbon dioxide (CO2) when it contacts the air above the charge; the closed furnace, in which
the gas is collected from the furnace and is either used as fuel for other processes or flared; and the
semi-covered furnace, in which mix is fed around the electrode openings in the primary furnace cover
resulting in mix seals. Electrode paste composed of coal tar pitch binder and anthracite coal is fed
into a steel casing where it is baked by heat from the electric arc furnace before being introduced into
the furnace. The baked electrode exits the steel casing just inside the furnace cover and is consumed
in the calcium carbide production process. Molten calcium carbide is tapped continuously from the
furnace into chills and is allowed to cool and solidify. Then, the solidified calcium carbide goes
through primary crushing by jaw crushers, followed by secondary crushing and screening for size.
To prevent explosion hazards from acetylene generated by the reaction of calcium carbide with
ambient moisture, crushing and screening operations may be performed in either an air-swept
environment before the calcium carbide has completely cooled, or in an inert atmosphere. The
calcium carbide product is used primarily in generating acetylene and in desulfurizing iron.
11.4.2 Emissions And Controls
Emissions from calcium carbide manufacturing include paniculate matter (PM), sulfur oxides
(SOX), CO, CO2, and hydrocarbons. Paniculate matter is emitted from a variety of equipment and
operations in the production of calcium carbide including the coke dryer, lime kiln, electric furnace,
tap fume vents, furnace room vents, primary and secondary crushers, and conveying equipment.
(Lime kiln emission factors are presented in Section 11.17). Paniculate matter emitted from a
process source such as an electric furnace is ducted to a PM control device, usually a fabric filter or
wet scrubber. Fugitive PM from sources such as tapping operations, the furnace room, and
conveyors is captured and sent to a PM control device. The composition of the PM varies according
1/95 Mineral Products Industry 11.4-1
-------
PM emissions
Gaseous emissions
Limestone
Coke
To
Flare
Primary
Fuel
Furnace
Room
Vents
SCC 3-05-004-03
Tap
Fume
Vents
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Coke
Dryer
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Electric
Arc
Furnace
SCC 3-05-004-01
(3)
A
Primary
Crushing
SCC 3-05-004-05
Secondary
Crushing
SCC 3-05-004-05
Acetylene
Generation
or
Cyanamide
Production
Figure 11.4-1. Process flow diagram for calcium carbide manufacturing.
(SCC = Source Classification Code).
11.4-2
EMISSION FACTORS
1/95
-------
to the specific equipment or operation, but the primary components are calcium and carbon
compounds, with significantly smaller amounts of magnesium compounds.
Sulfur oxides may be emitted both by the electric furnace from volatilization and oxidation of
sulfur in the coke feed, and by the coke dryer and lime kiln from fuel combustion. These process
sources are not controlled specifically for SOX emissions. Carbon monoxide is a byproduct of
calcium carbide production in the electric furnace. Carbon monoxide emissions to the atmosphere are
usually negligible. In open furnaces, CO is oxidized to CO2, thus eliminating CO emissions. In
closed furnaces, a portion of the generated CO is burned in the flames surrounding the furnace charge
holes, and the remaining CO is either used as fuel for other processes or is flared. In semi-covered
furnaces, the CO that is generated is either used as fuel for the lime kiln or other processes, or is
flared.
The only potential source of hydrocarbon emissions from the manufacture of calcium carbide
is the coal tar pitch binder in the furnace electrode paste. Since the maximum volatiles content in the
electrode paste is about 18 percent, the electrode paste represents only a small potential source of
hydrocarbon emissions. In closed furnaces, actual hydrocarbon emissions from the consumption of
electrode paste typically are negligible because of high furnace operating temperature and flames
surrounding the furnace charge holes. In open furnaces, hydrocarbon emissions are expected to be
negligible because of high furnace operating temperatures and the presence of excess oxygen above
the furnace. Hydrocarbon emissions from semi-covered furnaces are also expected to be negligible
because of high furnace operating temperatures.
Tables 11.4-1 and 11.4-2 give controlled and uncontrolled emission factors in metric and
English units, respectively, for various processes in the manufacture of calcium carbide. Controlled
factors are based on test data and permitted emissions for operations with the fabric filters and wet
scrubbers that are typically used to control PM emissions in calcium carbide manufacturing.
1/95 Mineral Products Industry 11.4-3
-------
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11.4-4
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1/95
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k EMISSION FACTOR RATING: D.
m Reference 12.
n Reference 1.
1/95
Mineral Products Industry
11.4-5
-------
References For Section 11.4
1. Permits To Operate: Airco Carbide, Louisville, Kentucky, Jefferson County Air Pollution
Control District, Louisville, KY, December 16, 1980.
2. Manufacturing Or Processing Operations: Airco Carbide, Louisville, Kentucky, Jefferson
County Air Pollution Control District, Louisville, KY, September 1975.
3. Written communication from A. J. Miles, Radian Corp., Research Triangle Park, NC, to
Douglas Cook, U. S. Environmental Protection Agency, Atlanta, GA, August 20, 1981.
4. Furnace Offgas Emissions Survey: Airco Carbide, Louisville, Kentucky, Environmental
Consultants, Inc., Clarksville, IN, March 17, 1975.
5. J. W. Frye, "Calcium Carbide Furnace Operation," Electric Furnace Conference Proceedings,
American Institute of Mechanical Engineers, NY, December 9-11, 1970.
6. The Louisville Air Pollution Study, U. S. Department of Health and Human Services,
Robert A. Taft Center, Cincinnati, OH, 1961.
7. R. N. Shreve and J. A. Brink, Jr., Chemical Process Industries, Fourth Edition, McGraw-
Hill Company, NY, 1977.
8. J. H. Stuever, Paniculate Emissions - Electric Carbide Furnace Test Report: Midwest
Carbide, Pryor, Oklahoma, Stuever and Associates, Oklahoma City, OK, April 1978.
9. L. Thomson, Paniculate Emissions Test Repon: Midwest Carbide, Keokuk, Iowa, Being
Consultants, Inc., Moline, IL, July 1, 1980.
10. D. M. Kirkpatrick, "Acetylene from Calcium Carbide Is an Alternate Feedstock Route," Oil
And Gas Journal, June 7, 1976.
11. L. Clarke and R. L. Davidson, Manual For Process Engineering Calculations, Second
Edition, McGraw-Hill Company, NY, 1962.
12. Test Report: Paniculate Emissions-Electric Carbide Furnace, Midwest Carbide Corporation,
Pryor, Oklahoma," Stuever and Associates, Oklahoma City, Oklahoma, April 1978.
13. Written communication from C. McPhee, State of Ohio EPA, Twinsburg, Ohio, to
R. Marinshaw, Midwest Research Institute, Gary, NC, March 16, 1993.
11.4-6 EMISSION FACTORS 1/95
-------
11.5 Refractory Manufacturing
11.5.1 Process Description1"2
Refractories are materials that provide linings for high-temperature furnaces and other
processing units. Refractories must be able to withstand physical wear, high temperatures (above
538°C [1000°F]), and corrosion by chemical agents. There are two general classifications of
refractories, clay and nonclay. The six-digit source classification code (SCC) for refractory
manufacturing is 3-05-005. Clay refractories are produced from fireclay (hydrous silicates of
aluminum) and alumina (57 to 87.5 percent). Other clay minerals used in the production of
refractories include kaolin, bentonite, ball clay, and common clay. Nonclay refractories are produced
from a composition of alumina (<87.5 percent), mullite, chromite, magnesite, silica, silicon carbide,
zircon, and other nonclays.
Refractories are produced in two basic forms, formed objects, and unformed granulated or
plastic compositions. The preformed products are called bricks and shapes. These products are used
to form the walls, arches, and floor tiles of various high-temperature process equipment. Unformed
compositions include mortars, gunning mixes, castables (refractory concretes), ramming mixes, and
plastics. These products are cured in place to form a monolithic, internal structure after application.
Refractory manufacturing involves four processes: raw material processing, forming, firing,
and final processing. Figure 11.5-1 illustrates the refractory manufacturing process. Raw material
processing consists of crushing and grinding raw materials, followed if necessary by size classification
and raw materials calcining and drying. The processed raw material then may be dry-mixed with
other minerals and chemical compounds, packaged, and shipped as product. All of these processes
are not required for some refractory products.
Forming consists of mixing the raw materials and forming them into the desired shapes. This
process frequently occurs under wet or moist conditions. Firing involves heating the refractory
material to high temperatures in a periodic (batch) or continuous tunnel kiln to form the ceramic bond
that gives the product its refractory properties. The final processing stage involves milling, grinding,
and sandblasting of the finished product. This step keeps the product in correct shape and size after
thermal expansion has occurred. For certain products, final processing may also include product
impregnation with tar and pitch, and final packaging.
Two other types of refractory processes also warrant discussion. The first is production of
fused products. This process involves using an electric arc furnace to melt the refractory raw
materials, then pouring the melted materials into sand-forming molds. Another type of refractory
process is ceramic fiber production. In this process, calcined kaolin is melted in an electric arc
furnace. The molten clay is either fiberized in a blowchamber with a centrifuge device or is dropped
into an air jet and immediately blown into fine strands. After the blowchamber, the ceramic fiber
may then be conveyed to an oven for curing, which adds structural rigidity to the fibers. During the
curing process, oils are used to lubricate both the fibers and the machinery used to handle and form
the fibers. The production of ceramic fiber for refractory material is very similar to the production of
mineral wool.
1/95 Mineral Products Industry 11.5-1
-------
TRANSPORTING
1 9
V T
STORAGE
1 ©
W *
CRUSHING/
GRINDING
(SCC 3-OS-OQ5-02)
1 ©
W *
SCREENING/
CLASSIFYING
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(SCC 3-05-005-01. -08)
I ©0
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(SCC 3-05-005-07. -09)
(T) PM EMISSIONS
(j2) GASEOUS EMISSIONS
?
WEATHERING (OPTIONAL)
<
? ?
*" CALCINING/ ,r,DTIOM4, !
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•< (SCC 3-05-005-01 . -06)
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X BLENDING * HAGKAOINb 1
(OPTIONAL)
t t i
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COOLING ^ FINISHING ^ ^ PINO
11.5-2
Figure 11.5-1. Refractory manufacturing process flow diagram.1
(Source Classification Codes in parentheses.)
EMISSION FACTORS
1/95
-------
11.5.2 Emissions And Controls2"6
The primary pollutant of concern in refractory manufacturing is paniculate matter (PM).
Paniculate matter emissions occur during the crushing, grinding, screening, calcining, and drying of
the raw materials; the drying and firing of the unfired "green" refractory bricks, tar and pitch
operations; and finishing of the refractories (grinding, milling, and sandblasting).
Emissions from crushing and grinding operations generally are controlled with fabric filters.
Product recovery cyclones followed by wet scrubbers are used on calciners and dryers to control PM
emissions from these sources. The primary sources of PM emissions are the refractory firing kilns
and electric arc furnaces. Paniculate matter emissions from kilns generally are not controlled.
However, at least one refractory manufacturer currently uses a multiple-stage scrubber to control kiln
emissions. Paniculate matter emissions from electric arc furnaces generally are controlled by a
baghouse. Paniculate removal of 87 percent and fluoride removal of greater than 99 percent have
been reported at one facility that uses an ionizing wet scrubber.
Pollutants emitted as a result of combustion in the calcining and kilning processes include
sulfur dioxide (SO^, nitrogen oxides (NOX), carbon monoxide (CO), carbon dioxide (CO2), and
volatile organic compounds (VOC). The emission of SOX is also a function of the sulfur content of
certain clays and the plaster added to refractory materials to induce brick setting. Fluoride emissions
occur during the kilning process because of fluorides in the raw materials. Emission factors for
filterable PM, PM-10, S02, NOX, and CO2 emissions from rotary dryers and calciners processing fire
clay are presented in Tables 11.5-1 and 11.5-2. Particle size distributions for filterable paniculate
emissions from rotary dryers and calciners processing fire clay are presented in Table 11.5-3.
Volatile organic compounds emitted from tar and pitch operations generally are controlled by
incineration, when inorganic particulates are not significant. Based on the expected destruction of
organic aerosols, a control efficiency in excess of 95 percent can be achieved using incinerators.
Chromium is used in several types of nonclay refractories, including chrome-magnesite,
(chromite-magnesite), magnesia-chrome, and chrome-alumina. Chromium compounds are emitted
from the ore crushing, grinding, material drying and storage, and brick firing and finishing processes
used in producing these types of refractories. Tables 11.5-4 and 11.5-5 present emission factors for
emissions of filterable PM, filterable PM-10, hexavalent chromium, and total chromium from the
drying and firing of chromite-magnesite ore. The emission factors are presented in units of kilograms
of pollutant emitted per megagram of chromite ore processed (kg/Mg Cr03) (pounds per ton of
chromite ore processed [Ib/ton CrO3]). Particle size distributions for the drying and firing of
chromite-magnesite ore are summarized in Table 11.5-6.
A number of elements in trace concentrations including aluminum, beryllium, calcium,
chromium, iron, lead, mercury, magnesium, manganese, nickel, titanium, vanadium, and zinc also
are emitted in trace amounts by the drying, calcining, and firing operations of all types of refractory
materials. However, data are inadequate to develop emission factors for these elements.
Emissions of PM from electric arc furnaces producing fused cast refractory material are
controlled with baghouses. The efficiency of the fabric filters often exceeds 99.5 percent. Emissions
of PM from the ceramic fiber process also are controlled with fabric filters, at an efficiency similar to
that found in the fused cast refractory process. To control blowchamber emissions, a fabric filter is
used to remove small pieces of fine threads formed in the fiberization stage. The efficiency of fabric
filters in similar control devices exceeds 99 percent. Small particles of ceramic fiber are broken off
1/95 Mineral Products Industry 11.5-3
-------
or separated during the handling and forming of the fiber blankets in the curing oven. An oil is used
in this process, and higher molecular weight organics may be emitted. However, these emissions
generally are controlled with a fabric filter followed by incineration, at an expected overall efficiency
in excess of 95 percent.
Table 11.5-1 (Metric Units). EMISSION FACTORS FOR REFRACTORY
MANUFACTURING: FIRE CLAYa
EMISSION FACTOR RATING: D
Process
Rotary dryerc
(SCC 3-05-005-01)
Rotary dryer with cyclone
(SCC 3-05-005-01)
Rotary dryer with cyclone and wet
scrubber0
(SCC 3-05-005-01)
Rotary calciner
(SCC 3-05-005-06)
Rotary calciner with multiclone
(SCC 3-05-005-06)
Rotary calciner with multiclone and
wet scrubber
(SCC 3-05-005-06)
SO2
ND
ND
ND
ND
ND
3.8d
NOX
ND
ND
ND
ND
ND
0.87d
CO2
15
15
15
300C
300C
300C
Filterable13
PM
33
5.6
0.052
62d
31f
0.15d
PM-10
8.1
2.6
ND
14e
ND
0.031s
a Factors represent uncontrolled emissions, unless noted. All emission factors in kg/Mg of raw
material feed. SCC = Source Classification Code. ND = no data.
b Filterable PM is that PM collected on or before the filter of an EPA Method 5 (or equivalent)
sampling train. PM-10 values are based on cascade impaction particle size distribution.
c Reference 3.
d References 4-5.
e Reference 4.
f Reference 5.
11.5-4
EMISSION FACTORS
1/95
-------
Table 11.5-2 (English Units). EMISSION FACTORS FOR REFRACTORY MANUFACTURING:
FIRE CLAYa
EMISSION FACTOR RATING: D
Process
Rotary dryer0
(SCC 3-05-005-01)
Rotary dryer with cyclone0
(SCC 3-05-005-01)
Rotary dryer with cyclone and wet
scrubber6
(SCC 3-05-005-01)
Rotary calciner
(SCC 3-05-005-06)
Rotary calciner with multiclone
(SCC 3-05-005-06)
Rotary calciner with multiclone
and wet scrubber
(SCC 3-05-005-06)
SO2
ND
ND
ND
ND
ND
7.6d
NOX
ND
ND
ND
ND
ND
1.7d
CO2
30
30
30
600C
600C
ND
Filterable15
PM PM-10
65 16
11 5.1
0.11 ND
120d 30e
61f ND
0.30d 0.062e
a Factors represent uncontrolled emissions, unless noted. All emission factors in Ib/ton of raw
material feed. SCC = Source Classification Code. ND = no data.
b Filterable PM is that PM collected on or before the filter of an EPA Method 5 (or equivalent)
sampling train. PM-10 values are based on cascade impaction particle size distribution.
c Reference 3.
d References 4-5.
e Reference 4.
f Reference 5.
1/95
Mineral Products Industry
11.5-5
-------
Table 11.5-3. PARTICLE SIZE DISTRIBUTIONS FOR REFRACTORY
MANUFACTURING: FIRECLAY1
EMISSION FACTOR RATING: D
Diameter
Om)
Uncontrolled
Cumulative %
Less Than
Diameter
Multiclone
Controlled
Cumulative %
Less Than
Diameter
Cyclone
Controlled
Cumulative %
Less Than
Diameter
Cyclone/Scrubber
Controlled
Cumulative %
Less Than
Diameter
Rotary Dryers (SCC 3-05-005-01)b
2.5
6.0
10.0
15.0
20.0
2.5
10
24
37
51
ND
ND
ND
ND
ND
14
31
46
60
68
ND
ND
ND
ND
ND
Rotary Calciners (SCC 3-05-005-06)°
1.0
1.25
2.5
6.0
10.0
15.0
20.0
3.1
4.1
6.9
17
34
50
62
13
14
23
39
50
63
81
ND
ND
ND
ND
ND
ND
ND
31
43
46
55
69
81
91
a For filterable PM only. ND = no data. SCC = Source Classification Code.
b Reference 3.
c References 4-5 (uncontrolled). Reference 4 (multiclone-controlled). Reference 5 (cyclone/scrubber-
controlled).
11.5-6
EMISSION FACTORS
1/95
-------
Table 11.5-4 (Metric Units). EMISSION FACTORS FOR REFRACTORY MANUFACTURING:
CHROMITE-MAGNESITE ORE3
EMISSION FACTOR RATING: D (except as noted)
Process
Rotary dryer (SCC 3-05-005-08)
Rotary dryer with
cyclone and fabric filter
(SCC 3-05-005-08)
Tunnel kiln (SCC 3-05-005-09)
Filterableb
PM
0.83
0.15
0.41
PM-10
0.20
ND
0.34
Chromium0
Hexavalent
3.8xlO-5
1.9xlO-5
0.0087
Total
0.035
0.064
0.13
a Reference 6. Factors represent uncontrolled emissions. Factors for filterable PM are kg/Mg of
material processed. Factors for chrominum are kg/Mg of chromite ore processed.
SCC = Source Classification Code for chromium. ND = no data.
b Filterable PM is that PM collected on or before the filter of an EPA Method 5 (or equivalent)
sampling train. PM-10 values are based on cascade impaction particle size distribution and
filterable PM emission factor.
c EMISSION FACTOR RATING: E.
Table 11.5-5 (English Units). EMISSION FACTORS FOR REFRACTORY MANUFACTURING:
CHROMITE-MAGNESITE OREa
EMISSION FACTOR RATING: D (except as noted)
Process
Rotary dryer (SCC 3-05-005-08)
Rotary dryer with
cyclone and fabric filter
(SCC 3-05-005-08)
Tunnel kiln (SCC 3-05-005-09)
Filterable6
PM
1.7
0.30
0.82
PM-10
0.41
ND
0.69
Chromium0
Hexavalent
7.6xlO-5
3.7xlO'5
0.017
Total
0.70
0.13
0.27
a Reference 6. Factors represent uncontrolled emissions. Factors for filterable PM are Ib/ton of
material processed. Factors for chromium are Ib/ton of chromite ore processed. SCC = Source
Classification Code. ND = no data.
b Filterable PM is that PM collected on or before the filter of an EPA Method 5 (or equivalent)
sampling train. PM-10 values are based on cascade impaction particle size distribution and
filterable PM emission factor.
c EMISSION FACTOR RATING: E.
1/95
Mineral Products Industry
11.5-7
-------
Table 11.5-6. PARTICLE SIZE DISTRIBUTIONS FOR REFRACTORY MANUFACTURING:
CHROMTTE-MAGNESITE ORE DRYING AND FIRINGa
Diameter
(fim)
Filterable PMb
Cumulative % Less
Than Diameter
Hexavalent Chromiumc
Cumulative % Less
Than Diameter
Total Chromium0
Cumulative % Less
Than Diameter
Uncontrolled rotary dryer (SCC 3-05-005-01)
1
2
10
1.2
13
24
3.5
39
64
0.8
9
19
Uncontrolled tunnel kiln (SCC 3-05-005-07)
1
5
10
71
78
84
71
81
84
84
91
93
a Reference 6. For filterable PM only. SCC = Source Classification Code.
b EMISSION FACTOR RATING: D.
c EMISSION FACTOR RATING: E.
or separated during the handling and forming of the fiber blankets in the curing oven. An oil is used
in this process, and higher molecular weight organics may be emitted. However, these emissions
generally are controlled with a fabric filter followed by incineration, at an expected overall efficiency
in excess of 95 percent.
References For Section 11.5
1. Refractories, The Refractories Institute, Pittsburgh, PA, 1987.
2. Source Category Survey: Refractory Industry, EPA-450/3-80-006, U. S. Environmental
Protection Agency, Research Triangle Park, NC, March 1980.
3. Calciners And Dryers Emission Test Report, North American Refractories Company, Farber,
Missouri, EMB Report 84-CDR-14, U. S. Environmental Protection Agency, Research
Triangle Park, NC, March 1984.
4. Emission Test Report: Plant A, Document No. C-7-12, Confidential Business Information
Files, BSD Project No. 81/08, U. S. Environmental Protection Agency, Research Triangle
Park, NC, June 13, 1983.
5. Calciners And Dryers Emission Test Report, A. P. Green Company, Mexico, Missouri, EMB
Report 83-CDR-l, U. S. Environmental Protection Agency, Research Triangle Park, NC,
October 1983.
11.5-8
EMISSION FACTORS
1/95
-------
6. Chromium Screening Study Test Report, Harbison-Walker Refractories, Baltimore, Maryland,
EMB Report 85-CHM-12, U. S. Environmental Protection Agency, Research Triangle Park,
NC, June 1985.
1/95 Mineral Products Industry 11.5-9
-------
11.6 Portland Cement Manufacturing
11.6.1 Process Description1"7
Portland cement is a fine powder, gray or white in color, that consists of a mixture of
hydraulic cement materials comprising primarily calcium silicates, aluminates and aluminoferrites.
More than 30 raw materials are known to be used in the manufacture of portland cement, and these
materials can be divided into four distinct categories: calcareous, siliceous, argillaceous, and
ferrifrous. These materials are chemically combined through pyroprocessing and subjected to
subsequent mechanical processing operations to form gray and white portland cement. Gray portland
cement is used for structural applications and is the more common type of cement produced. White
portland cement has lower iron and manganese contents than gray portland cement and is used
primarily for decorative purposes. Portland cement manufacturing plants are part of hydraulic cement
manufacturing, which also includes natural, masonry, and pozzolanic cement. The six-digit Source
Classification Code (SCC) for portland cement plants with wet process kilns is 3-05-006, and the
six-digit SCC for plants with dry process kilns is 3-05-007.
Portland cement accounts for 95 percent of the hydraulic cement production in the United
States. The balance of domestic cement production is primarily masonry cement. Both of these
materials are produced in portland cement manufacturing plants. A diagram of the process, which
encompasses production of both portland and masonry cement, is shown in Figure 11.6-1. As shown
in the figure, the process can be divided into the following primary components: raw materials
acquisition and handling, kiln feed preparation, pyroprocessing, and finished cement grinding. Each
of these process components is described briefly below. The primary focus of this discussion is on
pyroprocessing operations, which constitute the core of a portland cement plant.
The initial production step in portland cement manufacturing is raw materials acquisition.
Calcium, the element of highest concentration in portland cement, is obtained from a variety of
calcareous raw materials, including limestone, chalk, marl, sea shells, aragonite, and an impure
limestone known as "natural cement rock". Typically, these raw materials are obtained from open-
face quarries, but underground mines or dredging operations are also used. Raw materials vary from
facility to facility. Some quarries produce relatively pure limestone that requires the use of additional
raw materials to provide the correct chemical blend in the raw mix. In other quarries, all or part of
the noncalcarious constituents are found naturally in the limestone. Occasionally, pockets of pyrite,
which can significantly increase emissions of sulfur dioxide (SO2), are found in deposits of limestone,
clays, and shales used as raw materials for portland cement. Because a large fraction (approximately
one third) of the mass of this primary material is lost as carbon dioxide (CO2) in the kiln, portland
cement plants are located close to a calcareous raw material source whenever possible. Other
elements included in the raw mix are silicon, aluminum, and iron. These materials are obtained from
ores and minerals such as sand, shale, clay, and iron ore. Again, these materials are most commonly
from open-pit quarries or mines, but they may be dredged or excavated from underwater deposits.
Either gypsum or natural anhydrite, both of which are forms of calcium sulfate, is introduced
to the process during the finish grinding operations described below. These materials, also excavated
from quarries or mines, are generally purchased from an external source, rather than obtained directly
from a captive operation by the cement plant. The portland cement manufacturing industry is relying
increasingly on replacing virgin materials with waste materials or byproducts from other
manufacturing operations, to the extent that such replacement can be implemented without adversely
1/95 Mineral Products Industry 11.6-1
-------
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11.6-2
EMISSION FACTORS
1/95
-------
affecting plant operations, product quality or the environment. Materials that have been used include
fly ash, mill scale, and metal smelting slags.
The second step in portland cement manufacture is preparing the raw mix, or kiln feed, for
the pyroprocessing operation. Raw material preparation includes a variety of blending and sizing
operations that are designed to provide a feed with appropriate chemical and physical properties. The
raw material processing operations differ somewhat for wet and dry processes, as described below.
Cement raw materials are received with an initial moisture content varying from 1 to more
than 50 percent. If the facility uses dry process kilns, this moisture is usually reduced to less than
1 percent before or during grinding. Drying alone can be accomplished in impact dryers, drum
dryers, paddle-equipped rapid dryers, air separators, or autogenous mills. However, drying can also
be accomplished during grinding in ball-and-tube mills or roller mills. While thermal energy for
drying can be supplied by exhaust gases from separate, direct-fired coal, oil, or gas burners, the most
efficient and widely used source of heat for drying is the hot exit gases from the pyroprocessing
system.
Materials transport associated with dry raw milling systems can be accomplished by a variety
of mechanisms, including screw conveyors, belt conveyors, drag conveyors, bucket elevators, air
slide conveyors, and pneumatic conveying systems. The dry raw mix is pneumatically blended and
stored in specially constructed silos until it is fed to the pyroprocessing system.
In the wet process, water is added to the raw mill during the grinding of the raw materials in
ball or tube mills, thereby producing a pumpable slurry, or slip, of approximately 65 percent solids.
The slurry is agitated, blended, and stored in various kinds and sizes of cylindrical tanks or slurry
basins until it is fed to the pyroprocessing system.
The heart of the portland cement manufacturing process is the pyroprocessing system. This
system transforms the raw mix into clinkers, which are gray, glass-hard, spherically shaped nodules
that range from 0.32 to 5.1 centimeters (cm) (0.125 to 2.0 inches [in.]) in diameter. The chemical
reactions and physical processes that constitute the transformation are quite complex, but they can be
viewed conceptually as the following sequential events:
1. Evaporation of free water;
2. Evolution of combined water in the argillaceous components;
3. Calcination of the calcium carbonate (CaCO3) to calcium oxide (CaO);
4. Reaction of CaO with silica to form dicalcium silicate;
5. Reaction of CaO with the aluminum and iron-bearing constituents to form the liquid
phase;
6. Formation of the clinker nodules;
7. Evaporation of volatile constituents (e. g., sodium, potassium, chlorides, and sulfates);
and
8. Reaction of excess CaO with dicalcium silicate to form tricalcium silicate.
1/95 Mineral Products Industry 11.6-3
-------
This sequence of events may be conveniently divided into four stages, as a function of
location and temperature of the materials in the rotary kiln.
1. Evaporation of uncombined water from raw materials, as material temperature increases to
100°C (212°F);
2. Dehydration, as the material temperature increases from 100°C to approximately 430°C
(800°F) to form oxides of silicon, aluminum, and iron;
3. Calcination, during which carbon dioxide (CO2) is evolved, between 900°C (1650°F) and
982°C (1800°F), to form CaO; and
4. Reaction, of the oxides in the burning zone of the rotary kiln, to form cement clinker at
temperatures of approximately 1510°C (2750°F).
Rotary kilns are long, cylindrical, slightly inclined furnaces that are lined with refractory to
protect the steel shell and retain heat within the kiln. The raw material mix enters the kiln at the
elevated end, and the combustion fuels generally are introduced into the lower end of the kiln in a
countercurrent manner. The materials are continuously and slowly moved to the lower end by
rotation of the kiln. As they move down the kiln, the raw materials are changed to cementitious or
hydraulic minerals as a result of the increasing temperature within the kiln. The most commonly used
kiln fuels are coal, natural gas, and occasionally oil. The use of supplemental fuels such as waste
solvents, scrap rubber, and petroleum coke has expanded in recent years.
Five different processes are used in the portland cement industry to accomplish the
pyroprocessing step: the wet process, the dry process (long dry process), the semidry process, the
dry process with a preheater, and the dry process with a preheater/precalciner. Each of these
processes accomplishes the physical/chemical steps defined above. However, the processes vary with
respect to equipment design, method of operation, and fuel consumption. Generally, fuel
consumption decreases in the order of the processes listed. The paragraphs below briefly describe the
process, starting with the wet process and then noting differences in the other processes.
In the wet process and long dry process, all of the pyroprocessing activity occurs in the rotary
kiln. Depending on the process type, kilns have length-to-diameter ratios in the range of 15:1 to
40:1. While some wet process kilns may be as long as 210 m (700 ft), many wet process kilns and
all dry process kilns are shorter. Wet process and long dry process pyroprocessing systems consist
solely of the simple rotary kiln. Usually, a system of chains is provided at the feed end of the kiln in
the drying or preheat zones to improve heat transfer from the hot gases to the solid materials. As the
kiln rotates, the chains are raised and exposed to the hot gases. Further kiln rotation causes the hot
chains to fall into the cooler materials at the bottom of the kiln, thereby transferring the heat to the
load.
Dry process pyroprocessing systems have been improved in thermal efficiency and productive
capacity through the addition of one or more cyclone-type preheater vessels in the gas stream exiting
the rotary kiln. This system is called the preheater process. The vessels are arranged vertically, in
series, and are supported by a structure known as the preheater tower. Hot exhaust gases from the
rotary kiln pass countercurrently through the downward-moving raw materials in the preheater
vessels. Compared to the simple rotary kiln, the heat transfer rate is significantly increased, the
degree of heat utilization is greater, and the process time is markedly reduced by the intimate contact
of the solid particles with the hot gases. The improved heat transfer allows the length of the rotary
kiln to be reduced. The hot gases from the preheater tower are often used as a source of heat for
11.6-4 EMISSION FACTORS 1/95
-------
drying raw materials in the raw mill. Because the catch from the mechanical collectors, fabric filters,
and/or electrostatic precipitators (ESP) that follow the raw mill is returned to the process, these
devices are considered to be production machines as well as pollution control devices.
Additional thermal efficiencies and productivity gains have been achieved by diverting some
fuel to a calciner vessel at the base of the preheater tower. This system is called the
preheater/precalciner process. While a substantial amount of fuel is used in the precalciner, at least
40 percent of the thermal energy is required in the rotary kiln. The amount of fuel that is introduced
to the calciner is determined by the availability and source of the oxygen for combustion in the
calciner. Calciner systems sometimes use lower-quality fuels (e. g., less-volatile matter) as a means
of improving process economics.
Preheater and precalciner kiln systems often have an alkali bypass system between the feed
end of the rotary kiln and the preheater tower to remove the undesirable volatile constituents.
Otherwise, the volatile constituents condense in the preheater tower and subsequently recirculate to
the kiln. Buildup of these condensed materials can restrict process and gas flows. The alkali content
of portland cement is often limited by product specifications because excessive alkali metals (i. e.,
sodium and potassium) can cause deleterious reactions in concrete. In a bypass system, a portion of
the kiln exit gas stream is withdrawn and quickly cooled by air or water to condense the volatile
constituents to fine particles. The solid particles, containing the undesirable volatile constituents, are
removed from the gas stream and thus the process by fabric filters and ESPs.
The semidry process is a variation of the dry process. In the semidry process, the water is
added to the dry raw mix in a pelletizer to form moist nodules or pellets. The pellets then are
conveyed on a moving grate preheater before being fed to the rotary kiln. The pellets are dried and
partially calcined by hot kiln exhaust gases passing through the moving grate.
Regardless of the type of pyroprocess used, the last component of the pyroprocessing system
is the clinker cooler. This process step recoups up to 30 percent of the heat input to the kiln system,
locks in desirable product qualities by freezing mineralogy, and makes it possible to handle the cooled
clinker with conventional conveying equipment. The more common types of clinker coolers are
(1) reciprocating grate, (2) planetary, and (3) rotary. In these coolers, the clinker is cooled from
about 1100°C to 93 °C (2000°F to 200°F) by ambient air that passes through the clinker and into the
rotary kiln for use as combustion air. However, in the reciprocating grate cooler, lower clinker
discharge temperatures are achieved by passing an additional quantity of air through the clinker.
Because this additional air cannot be utilized in the kiln for efficient combustion, it is vented to the
atmosphere, used for drying coal or raw materials, or used as a combustion air source for the
precalciner.
The final step in portland cement manufacturing involves a sequence of blending and grinding
operations that transforms clinker to finished portland cement. Up to 5 percent gypsum or natural
anhydrite is added to the clinker during grinding to control the cement setting time, and other
specialty chemicals are added as needed to impart specific product properties. This finish milling is
accomplished almost exclusively in ball or tube mills. Typically, finishing is conducted in a closed-
circuit system, with product sizing by air separation.
11.6.2 Emissions And Controls1'3"7
Particulate matter (PM and PM-10), nitrogen oxides (NOX), sulfur dioxide (SO2), carbon
monoxide (CO), and CO2 are the primary emissions in the manufacture of portland cement. Small
quantities of volatile organic compounds (VOC), ammonia (NH3), chlorine, and hydrogen chloride
1/95 Mineral Products Industry 11.6-5
-------
(HC1), also may be emitted. Emissions may also include residual materials from the fuel and raw
materials or products of incomplete combustion that are considered to be hazardous. Because some
facilities burn waste fuels, particularly spent solvents in the kiln, these systems also may emit small
quantities of additional hazardous organic pollutants. Also, raw material feeds and fuels typically
contain trace amounts of heavy metals that may be emitted as a paniculate or vapor.
Sources of PM at cement plants include (1) quarrying and crushing, (2) raw material storage,
(3) grinding and blending (in the dry process only), (4) clinker production, (5) finish grinding, and
(6) packaging and loading. The largest emission source of PM within cement plants is the
pyroprocessing system that includes the kiln and clinker cooler exhaust stacks. Often, dust from the
kiln is collected and recycled into the kiln, thereby producing clinker from the dust. However, if the
alkali content of the raw materials is too high, some or all of the dust is discarded or leached before
being returned to the kiln. In many instances, the maximum allowable cement alkali content of
0.6 percent (calculated as sodium oxide) restricts the amount of dust that can be recycled. Bypass
systems sometimes have a separate exhaust stack. Additional sources of PM are raw material storage
piles, conveyors, storage silos, and unloading facilities. Emissions from portland cement plants
constructed or modified after August 17, 1971 are regulated to limit PM emissions from portland
cement kilns to 0.15 kg/Mg (0.30 Ib/ton) of feed (dry basis), and to limit PM emissions from clinker
coolers to 0.050 kg/Mg (0.10 Ib/ton) of feed (dry basis).
Oxides of nitrogen are generated during fuel combustion by oxidation of chemically-bound
nitrogen in the fuel and by thermal fixation of nitrogen in the combustion air. As flame temperature
increases, the amount of thermally generated NOX increases. The amount of NOX generated from fuel
increases with the quantity of nitrogen in the fuel. In the cement manufacturing process, NOX is
generated in both the burning zone of the kiln and the burning zone of a precalcining vessel. Fuel
use affects the quantity and type of NOX generated. For example, in the kiln, natural gas combustion
with a high flame temperature and low fuel nitrogen generates a larger quantity of NOX than does oil
or coal, which have higher fuel nitrogen but which burn with lower flame temperatures. The
opposite may be true in a precalciner. Types of fuels used vary across the industry. Historically,
some combination of coal, oil, and natural gas was used, but over the last 15 years, most plants have
switched to coal, which generates less NOX than does oil or gas. However, in recent years a number
of plants have switched to systems that burn a combination of coal and waste fuel. The effect of
waste fuel use on NOX emissions is not clearly established.
Sulfur dioxide may be generated both from the sulfur compounds in the raw materials and
from sulfur in the fuel. The sulfur content of both raw materials and fuels varies from plant to plant
and with geographic location. However, the alkaline nature of the cement provides for direct
absorption of S02 into the product, thereby mitigating the quantity of S02 emissions in the exhaust
stream. Depending on the process and the source of the sulfur, SO2 absorption ranges from about
70 percent to more than 95 percent.
The CO2 emissions from portland cement manufacturing are generated by two mechanisms.
As with most high-temperature, energy-intensive industrial processes, combusting fuels to generate
process energy releases substantial quantities of CO2. Substantial quantities of CO2 also are
generated through calcining of limestone or other calcareous material. This calcining process
thermally decomposes CaCO3 to CaO and CO2. Typically, portland cement contains the equivalent
of about 63.5 percent CaO. Consequently, about 1.135 units of CaCO3 are required to produce 1
unit of cement, and the amount of CO2 released in the calcining process is about 500 kilograms (kg)
per Mg of portland cement produced (1,000 pounds [Ib] per ton of cement). Total CO2 emissions
from the pyroprocess depend on energy consumption and generally fall in the range of 0.85 to
1.35 Mg of CO2 per Mg of clinker.
11.6-6 EMISSION FACTORS 1/95
-------
In addition to CO2 emissions, fuel combustion at portland cement plants can emit a wide
range of pollutants in smaller quantities. If the combustion reactions do not reach completion, CO
and volatile organic pollutants, typically measured as total organic compounds (TOC), VOC, or
organic condensable particulate, can be emitted. Incomplete combustion also can lead to emissions of
specific hazardous organic air pollutants, although these pollutants are generally emitted at
substantially lower levels than CO or TOC.
Emissions of metal compounds from portland cement kilns can be grouped into three general
classes: volatile metals, including mercury (Hg) and thallium (Tl); semivolatile metals, including
antimony (Sb), cadmium (Cd), lead (Pb), selenium (Se), zinc (Zn), potassium (K), and sodium (Na);
and refractory or nonvolatile metals, including barium (Ba), chromium (Cr), arsenic (As), nickel (Ni),
vanadium (V), manganese (Mn), copper (Cu), and silver (Ag). Although the partitioning of these
metal groups is affected by kiln operating conditions, the refractory metals tend to concentrate in the
clinker, while the volatile and semivolatile metals tend to be discharged through the primary exhaust
stack and the bypass stack, respectively.
Fugitive dust sources in the industry include quarrying and mining operations, vehicle traffic
during mineral extraction and at the manufacturing site, raw materials storage piles, and clinker
storage piles. The measures used to control emissions from these fugitive dust sources are
comparable to those used throughout the mineral products industries. Vehicle traffic controls include
paving and road wetting. Controls that are applied to other open dust sources include water sprays
with and without surfactants, chemical dust suppressants, wind screens, and process modifications to
reduce drop heights or enclose storage operations. Additional information on these control measures
can be found in Chapter 13 of AP-42, "Miscellaneous Sources".
Process fugitive emission sources include materials handling and transfer, raw milling
operations in dry process facilities, and finish milling operations. Typically, emissions from these
processes are captured by a ventilation system and collected in fabric filters. Some facilities use an
air pollution control system comprising one or more mechanical collectors with a fabric filter in
series. Because the dust from these units is returned to the process, they are considered to be process
units as well as air pollution control devices. The industry uses shaker, reverse air, and pulse jet
filters as well as some cartridge units, but most newer facilities use pulse jet filters. For process
fugitive operations, the different systems are reported to achieve typical outlet PM loadings of
45 milligrams per cubic meter (mg/m3) (0.02 grains per actual cubic foot [gr/acf]).
In the pyroprocessing units, PM emissions are controlled by fabric filters (reverse air, pulse
jet, or pulse plenum) and electrostatic precipitators (ESP). Typical control measures for the kiln
exhaust are reverse air fabric filters with an air-to-clodi ratio of 0.41:1 m3/min/m2 (1.5:1 acfm/ft2)
and ESP with a net surface collection area of 1,140 to 1,620 m2/l,000 m3 (350 to 500 ft2/l,000 ft3).
These systems are reported to achieve outlet PM loadings of 45 mg/m3 (0.02 gr/acf). Clinker cooler
systems are controlled most frequently with pulse jet or pulse plenum fabric filters. A few gravel bed
filters also have been used to control clinker cooler emissions. Typical outlet PM loadings are
identical to those reported for kilns.
Cement kiln systems have highly alkaline internal environments that can absorb up to
95 percent of potential SO2 emissions. However, in systems that have sulfide sulfur (pyrites) in the
kiln feed, the sulfur absorption rate may be as low as 70 percent without unique design considerations
or changes in raw materials. The cement kiln system itself has been determined to provide substantial
SO2 control. Fabric filters on cement kilns are also reported to absorb SO2. Generally, substantial
control is not achieved. An absorbing reagent (e. g., CaO) must be present in the filter cake for SO2
capture to occur. Without the presence of water, which is undesirable in the operation of a fabric
1/95 Mineral Products Industry 11.6-7
-------
filter, CaCO3 is not an absorbing reagent. It has been observed that as much as 50 percent of the
SO2 can be removed from the pyroprocessing system exhaust gases when this gas stream is used in a
raw mill for heat recovery and drying. In this case, moisture and calcium carbonate are
simultaneously present for sufficient time to accomplish the chemical reaction with SO2.
Tables 11.6-1 and 11.6-2 present emission factors for PM emissions from portland cement
manufacturing kilns and clinker coolers. Tables 11.6-3 and 11.6-4 present emission factors for PM
emissions from raw material and product processing and handling. Particle size distributions for
emissions from wet process and dry process kilns are presented in Table 11.6-5, and Table 11.6-6
presents the particle size distributions for emissions from clinker coolers. Emission factors for SO2,
NOX, CO, CO2, and TOC emissions from portland cement kilns are summarized in Tables 11.6-7 and
11.6-8. Table 11.6-9 summarizes emission factors for other pollutant emissions from portland cement
kilns.
Because of differences in the sulfur content of the raw material and fuel and in process
operations, a mass balance for sulfur may yield a more representative emission factor for a specific
facility than the SO2 emission factors presented in Tables 11.6-7 and 11.6-8. In addition, CO2
emission factors estimated using a mass balance on carbon may be more representative for a specific
facility than the CO2 emission factors presented in Tables 11.6-7 and 11.6-8.
11.6-8 EMISSION FACTORS 1/95
-------
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Mineral Products Industry
11.6-9
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11.6-12
EMISSION FACTORS
1/95
-------
Table 11.6-3 (Metric Units). EMISSION FACTORS FOR PORTLAND CEMENT
MANUFACTURING RAW MATERIAL AND PRODUCT PROCESSING AND HANDLING3
Process
Raw mill with fabric filter
(SCC 3-05-006-13)
Raw mill feed belt with fabric filter
(SCC 3-05-006-24)
Raw mill weigh hopper with fabric filter
(SCC 3-05-006-25)
Raw mill air separator with fabric filter
(SCC 3-05-006-26)
Finish grinding mill with fabric filter
(SCC 3-05-006-17, 3-05-007-17)
Finish grinding mill feed belt with fabric filter
(SCC 3-05-006-27, 3-05-007-27)
Finish grinding mill weigh hopper with fabric filter
(SCC 3-05-006-28, 3-05-007-28)
Finish grinding mill air separator with fabric filter
(SCC 3-05-006-29, 3-05-007-29)
Primary limestone crushing with fabric filter
(SCC 3-05-006-09)h
Primary limestone screening with fabric filter
(SCC 3-05-006-1 l)h
Limestone transfer with fabric filter
(SCC 3-05-006- 12)h
Secondary limestone screening and crushing with
fabric filter
(SCC 3-05-006-10 + -11, 3-05-007-10 + -ll)h
PM
0.0062C
0.0016d
0.0106
0.016e
0.0042f
0.0012d
0.00476
0.0148
0.00050
0.00011
1.5 x 10-5
0.00016
Filterableb
EMISSION
FACTOR
RATING
D
E
E
E
D
E
E
D
E
E
E
E
PM-10
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
EMISSION
FACTOR
RATING
a Factors represent uncontrolled emissions, unless otherwise noted. Factors are kg/Mg of material
process, unless noted. SCC = Source Classification Code. ND = no data.
Filterable PM is that collected on or before the filter of an EPA Method 5 (or equivalent) sampling
train.
c References 15,56-57.
d Reference 57.
e Reference 15.
f References 10,12,15,56-57.
g References 10,15.
h Reference 16. Alternatively, emission factors from Section 11.19.2, "Crushed Stone Processing",
can be used for similar processes and equipment.
1/95
Mineral Products Industry
11.6-13
-------
Table 11.6-4 (English Units). EMISSION FACTORS FOR PORTLAND CEMENT
MANUFACTURING RAW MATERIAL AND PRODUCT PROCESSING AND HANDLINGa
Process
Raw mill with fabric filter
(SCC 3-05-006-13)
Raw mill feed belt with fabric filter
(SCC 3-05-006-24)
Raw mill weigh hopper with fabric filter
(SCC 3-05-006-25)
Raw mill air separator with fabric filter
(SCC 3-05-006-26)
Finish grinding mill with fabric filter
(SCC 3-05-006-17, 3-05-007-17)
Finish grinding mill feed belt with fabric filter
(SCC 3-05-006-27, 3-05-007-27)
Finish grinding mill weigh hopper with fabric filter
(SCC 3-05-006-28, 3-05-007-28)
Finish grinding mill air separator with fabric filter
(SCC 3-05-006-29, 3-05-007-29)
Primary limestone crushing with fabric filter
(SCC 3-05-006-09)h
Primary limestone screening with fabric filter
(SCC 3-05-006-1 l)h
Limestone transfer with fabric filter
(SCC 3-05-006-12)h
Secondary limestone screening and crushing with
fabric filter
(SCC 3-05-006-10 + -11, 3-05-007-10 + -ll)h
PM
0.012C
0.003 ld
0.019e
0.0326
0.0080f
0.0024d
0.0094e
0.0288
0.0010
0.00022
2.9 x 10'5
0.00031
Filterableb
EMISSION
FACTOR
RATING
D
E
E
E
E
E
E
D
E
E
E
E
PM-10
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
EMISSION
FACTOR
RATING
a Factors represent uncontrolled emissions, unless otherwise noted. Factors are Ib/ton of material
processed, unless noted. SCC = Source Classification Code. ND = no data.
b Filterable PM is that collected on or before the filter of an EPA Method 5 (or equivalent) sampling
train.
c References 15,56-57.
d Reference 57.
e Reference 15.
f References 10,12,15,56-57.
s References 10,15.
h Reference 16. Alternatively, emission factors from the Section 11.19.2, "Crushed Stone
Processing", can be used for similar processes and equipment.
11.6-14
EMISSION FACTORS
1/95
-------
Table 11.6-5. SUMMARY OF AVERAGE PARTICLE SIZE DISTRIBUTION
FOR PORTLAND CEMENT KILNSa
Particle
Size, fim
2.5
5.0
10.0
15.0
20.0
Cumulative Mass Percent Equal To Or Less Than Stated Size
Uncontrolled
Wet process
(SCC 3-05-007-06)
7
20
24
35
57
Dry process
(SCC 3-05-006-06)
18
ND
42
44
ND
Controlled
Wet process
With ESP
(SCC 3-05-007-06)
64
83
85
91
98
Dry process
WithFF
(SCC 3-05-006-06)
45
77
84
89
100
Reference 3. SCC = Source Classification Code. ND = no data.
Table 11.6-6. SUMMARY OF AVERAGE PARTICLE SIZE DISTRIBUTION
FOR PORTLAND CEMENT CLINKER COOLERS3
Particle Size, /zm
2.5
5.0
10.0
15.0
20.0
Cumulative Mass Percent Equal To Or Less Than Stated Size
Uncontrolled
(SCC 3-05-006-14, 3-05-007-14)
0.54
1.5
8.6
21
34
With Gravel Bed Filter
(SCC 3-05-006-14, 3-05-007-14)
40
64
76
84
89
a Reference 3. SCC = Source Classification Code.
1/95
Mineral Products Industry
11.6-15
-------
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11.6-16
EMISSION FACTORS
1/95
-------
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Mineral Products Industry
11.6-17
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1/95
Mineral Products Industry
11.6-19
-------
Table 11.6-9 (Metric And English Units). SUMMARY OF NONCRTTERIA POLLUTANT
EMISSION FACTORS FOR PORTLAND CEMENT KILNSa
(SCC 3-05-006-06, 3-05-007-06, 3-05-006-22, 3-05-006-23)
Pollutant
Name
Type Of
Control
Average Emission Factor
kg/Mg
Inorganic Pollutants
Silver (Ag)
Aluminum (Al)
Arsenic (As)
Arsenic (As)
Barium (Ba)
Barium (Ba)
Beryllium (Be)
Calcium (Ca)
Cadmium (Cd)
Cadmium (Cd)
Chloride (Cl)
Chloride (Cl)
Chromium (Cr)
Chromium (Cr)
Copper (Cu)
Fluoride (F)
Iron (Fe)
Hydrogen chloride (HC1)
Hydrogen chloride (HC1)
Mercury (Hg)
Mercury (Hg)
Potassium (K)
Manganese (Mn)
Ammonia (NH3)
Ammonium (NH^
Nitrate (NO3)
Sodium (Na)
Lead(Pb)
Lead(Pb)
Sulfur trioxide (SO3)
Sulfur trioxide (SO3)
Sulfate (804)
Sulfate (804)
FF
ESP
ESP
FF
ESP
FF
FF
ESP
ESP
FF
ESP
FF
ESP
FF
FF
ESP
ESP
ESP
FF
ESP
FF
ESP
ESP
FF
ESP
ESP
ESP
ESP
FF
ESP
FF
ESP
FF
S.lxlO'7
0.0065
6.5x10-*
6.0x10"*
0.00018
0.00023
3.3xlO'7
0.12
4.2x10-*
1.1x10-*
0.34
0.0011
3.9x10-*
7.0xlO'5
0.0026
0.00045
0.0085
0.025
0.073
0.00011
1.2xlQ-5
0.0090
0.00043
0.0051
0.054
0.0023
0.020
0.00036
3.8xlO-5
0.042
0.0073
0.10
0.0036
Ib/ton
EMISSION
FACTOR
RATING
References
6.1xlO'7
0.013
l.SxlO'5
1.2xlO-5
0.00035
0.00046
6.6xlO'7
0.24
8.3x10-*
2.2x10"*
0.68
0.0021
7.7x10-*
0.00014
0.0053
0.00090
0.017
0.049
0.14
0.00022
2.4xlO-5
0.018
0.00086
0.010
0.11
0.0046
0.038
0.00071
7.5xlQ-5
0.086
0.014
0.20
0.0072
D
E
E
D
D
D
D
E
D
D
E
D
E
D
E
E
E
E
D
D
D
D
E
E
D
E
D
D
D
E
D
D
D
63
65
65
63
64
63
63
65
64
63
25,42-44
63
64
63
62
43
65
41,65
59,63
64
11,63
25,42-43
65
59
25,42-W
43
25,42-44
64
63
25
24,30,50
25,42-44
30,33,52
11.6-20
EMISSION FACTORS
1/95
-------
Table 11.6-9 (cont.).
Pollutant
Name
Selenium (Se)
Selenium (Se)
Thallium (Th)
Titanium (Ti)
Zinc (Zn)
Zinc (Zn)
Type Of
Control
ESP
FF
FF
ESP
ESP
FF
Average Emission Factor
kg/Mg
7.5xlO-5
0.00010
2.7X1Q-6
0.00019
0.00027
0.00017
Ib/ton
0.00015
0.00020
5.4X10"6
0.00037
0.00054
0.00034
EMISSION
FACTOR
RATING
E
E
D
E
D
D
References
65
62
63
65
64
63
Organic Pollutants
CASRNb j Name
35822-46-9 1,2,3,4,6,7,8 HpCDD
C3 benzenes
C4 benzenes
C6 benzenes
208-96-8 acenaphthylene
67-64-1 acetone
100-52-7 benzaldehyde
71-43-2 benzene
71-43-2 benzene
ber.zo(a)anthracene
50-32-8 benzo(a)pyrene
205-99-2 benzo(b)fluoranthene
191-24-2 benzo(g,h,i)perylene
207-08-9 benzo(k)fluoranthene
65-85-0 benzoic acid
95-52-4 biphenyl
117-81-7 bis(2-ethylhexyl)phthalate
74-83-9 bromomethane
75-15-0 carbon disulfide
108-90-7 chlorobenzene
74-87-3 chloromethane
218-01-9 chrysene
84-74-2 di-n-butylphthalate
53-70-3 dibenz(a,h)anthracene
101-41-4 ethylbenzene
206-44-0 fluoranthene
86-73-7 fluorene
50-00-0 formaldehyde
FF
ESP
ESP
ESP
FF
ESP
ESP
ESP
FF
FF
FF
FF
FF
FF
ESP
ESP
ESP
ESP
ESP
ESP
ESP
FF
ESP
FF
ESP
FF
FF
FF
l.lxlO-10
1.3xlO'6
S.OxlO"6
4.6xlO'7
5.9xlO"5
0.00019
1.2xlO'5
0.0016
0.0080
2.1xlO'8
6.5xlO'8
2.8xlO'7
3.9xlO'8
7.7X10-8
0.0018
3.1xlO'6
4.8xlO'5
2.2xlO'5
5.5xlO-5
8-OxlO-6
0.00019
S.lxlQ-8
2.1xlO'5
3-lxlO'7
9.5xlO'6
4.4xlO'6
9.4xlO'6
0.00023
2.2x10" 10
2.6x10-*
6.0x10-*
9.2xlO-7
0.00012
0.00037
2.4xlO-5
0.0031
0.016
4.3X10"8
l.SxlO"7
5.6xlO'7
7.8X1Q-8
l.SxlO-7
0.0035
6.1xlO'6
9.5xlO's
4.3xlO'5
0.00011
1.6xlO-5
0.00038
1.6X10'7
4.1xlO'5
6.3xlO'7
1.9xlO'5
S.SxlO-6
1.9xlO"5
0.00046
E
E
E
E
E
D
E
D
E
E
E
E
E
E
D
E
D
E
D
D
E
E
D
E
D
E
E
E
62
65
65
65
62
64
65
64
62
62
62
62
62
62
64
65
64
64
64
64
64
62
64
62
64
62
62
62
1/95
Mineral Products Industry
11.6-21
-------
Table 11.6-9 (com.).
Pollutant
CASRNb
193-39-5
78-93-3
75-09-2
91-20-3
91-20-3
85-01-8
108-95-2
129-00-0
100-42-5
108-88-3
3268-87-9
132-64-9
132-64-9
1330-20-7
Name
freon 113
indeno(l ,2,3-cd)pyrene
methyl ethyl ketone
methylene chloride
methylnaphthalene
naphthalene
naphthalene
phenanthrene
phenol
pyrene
styrene
toluene
total HpCDD
total OCDD
total PCDD
total PCDF
total TCDF
xylenes
Type Of
Control
ESP
FF
ESP
ESP
ESP
FF
ESP
FF
ESP
FF
ESP
ESP
FF
FF
FF
FF
FF
ESP
Average Emission Factor
kg/Mg
2.5xlO-5
4.3x10-*
l.SxlO'5
0.00025
2.1x10-*
0.00085
0.00011
0.00020
S.SxlO'5
2.2X10-6
7.5x1 0'7
0.00010
2.0xlO-10
l.OxlO-9
1.4xlO-9
1.4x10-'°
1.4X10'10
6.5xlQ-5
Ib/ton
S.OxlO'5
8.7X10-8
3.0xlO'5
0.00049
4.2X10-6
0.0017
0.00022
0.00039
0.00011
4.4X10-6
1.5x10-*
0.00019
3.9xlO-10
2.0xlO-9
2.7xlO-9
2.9X10'10
2.9xlO'10
0.00013
EMISSION
FACTOR
RATING
E
E
E
E
E
E
D
E
D
E
E
D
E
E
E
E
E
D
References
65
62
64-65
65
65
62
64
62
64
62
65
64
62
62
62
62
62
64
a Factors are kg/Mg and Ib/ton of clinker produced. SCC = Source Classification Code.
ESP = electrostatic precipitator. FF = fabric filter.
b Chemical Abstract Service Registry Number (organic compounds only).
References For Section 11.6
1. W. L. Greer, et al., "Portland Cement", Air Pollution Engineering Manual, A. J. Buonicore
and W. T. Davis (eds.), Von Nostrand Reinhold, NY, 1992.
2. U. S. And Canadian Portland Cement Industry Plant Information Summary, December 31,
1990, Portland Cement Association, Washington, DC, August 1991.
3. J. S. Kinsey, Lime And Cement Industry - Source Category Report, Volume II, EPA-600/7-87-
007, U. S. Environmental Protection Agency, Cincinnati, OH, February 1987.
4. Written communication from Robert W. Crolius, Portland Cement Association, Washington,
DC, to Ron Myers, U. S. Environmental Protection Agency, Research Triangle Park, NC.
March 11, 1992.
5. Written communication from Walter Greer, Ash Grove Cement Company, Overland Park,
KS, to Ron Myers, U. S. Environmental Protection Agency, Research Triangle Park, NC,
September 30, 1993.
11.6-22
EMISSION FACTORS
1/95
-------
6. Written communication from John Wheeler, Capitol Cement, San Antonio, TX, to Ron
Myers, U. S. Environmental Protection Agency, Research Triangle Park, NC, September 21,
1993.
7. Written communication from F. L. Streitman, ESSROC Materials, Incorporated, Nazareth,
PA, to Ron Myers, U. S. Environmental Protection Agency, Research Triangle Park, NC,
September 29, 1993.
8. Emissions From Wet Process Cement Kiln And Clinker Cooler At Maule Industries, Inc., ETB
Test No. 71-MM-01, U. S. Environmental Protection Agency, Research Triangle Park, NC,
March 1972.
9. Emissions From Wet Process Cement Kiln And Clinker Cooler At Ideal Cement Company,
ETB Test No. 71-MM-03, U. S. Environmental Protection Agency, Research Triangle Park,
NC, March 1972.
10. Emissions From Wet Process Cement Kiln And Finish Mill Systems At Ideal Cement Company,
ETB Test No. 71-MM-04, U. S. Environmental Protection Agency, Research Triangle Park,
NC, March 1972.
11. Emissions From Dry Process Cement Kiln At Dragon Cement Company, ETB Test No.
71-MM-05, U. S. Environmental Protection Agency, Research Triangle Park, NC, March
1972.
12. Emissions From Wet Process Clinker Cooler And Finish Mill Systems At Ideal Cement
Company, ETB Test No. 71-MM-06, U. S. Environmental Protection Agency, Research
Triangle Park, NC, March 1972.
13. Emissions From Wet Process Cement Kiln At Giant Portland Cement, ETB Test No.
71-MM-07, U. S. Environmental Protection Agency, Research Triangle Park, NC, March
1972.
14. Emissions From Wet Process Cement Kiln At Oregon Portland Cement, ETB Test No.
71-MM-15, U. S. Environmental Protection Agency, Research Triangle Park, NC, March
1972.
15. Emissions From Dry Process Raw Mill And Finish Mill Systems At Ideal Cement Company,
ETB Test No. 71-MM-02, U. S. Environmental Protection Agency, Research Triangle Park,
NC, April 1972.
16. Part I, Air Pollution Emission Test: Arizona Portland Cement, EPA Project Report No.
74-STN-l, U. S. Environmental Protection Agency, Research Triangle Park, NC, June 1974.
17. Characterization Oflnhalable Paniculate Matter Emissions From A Dry Process Cement
Plant, EPA Contract No. 68-02-3158, Midwest Research Institute, Kansas City, MO,
February 1983.
18. Characterization Oflnhalable Paniculate Matter Emissions From A Wet Process Cement
Plant, EPA Contract No. 68-02-3158, Midwest Research Institute, Kansas City, MO, August
1983.
1/95 Mineral Products Industry 11.6-23
-------
19. Paniculate Emission Testing At Lone Star Industries'Nazareth Plant, Lone Star Industries,
Inc., Houston, TX, January 1978.
20. Participate Emissions Testing At Lone Star Industries' Greencastle Plant, Lone Star
Industries, Inc., Houston, TX, July 1977.
21. Gas Process Survey At Lone Star Cement, Inc. 's Roanoke No. 5 Kiln System, Lone Star
Cement, Inc., Cloverdale, VA, October 1979.
22. Test Report: Stack Analysis For Paniculate Emissions: Clinker Coolers/Gravel Bed Filter,
Mease Engineering Associates, Port Matilda, PA, January 1993.
23. Source Emissions Survey Of Oklahoma Cement Company's Kiln Number 3 Stack, Mull ins
Environmental Testing Co., Inc., Addison, TX, March 1980.
24. Source Emissions Survey Of Lone Star Industries, Inc.: Kilns 1, 2, and 3, Mullins
Environmental Testing Co., Inc., Addison, TX, June 1980.
25. Source Emissions Survey Of Lone Star Industries, Inc., Mullins Environmental Testing Co.,
Inc., Addison, TX, November 1981.
26. Stack Emission Survey And Precipitator Efficiency Testing At Banner Springs Plant, Lone Star
Industries, Inc., Houston, TX, November 1981.
27. NSPS Paniculate Emission Compliance Test: No. 8 Kiln, Interpoll, Inc., Elaine, MN, March
1983.
28. Annual Compliance Test: Mojave Plant, Pape & Steiner Environmental Services, Bakersfield,
CA, May 1983.
29. Source Emissions Survey OfLehigh Ponland Cement Company, Mullins Environmental
Testing Co., Inc., Addison, TX, August 1983.
30. Annual Compliance Test: Mojave Plant, Pape & Steiner Environmental Services, Bakersfield,
CA, May 1984.
31. Paniculate Compliance Test: Lehigh Ponland Cement Company, CH2M Hill, Montgomery,
AL, October 1984.
32. Compliance Test Results: Paniculate & Sulfur Oxide Emissions At Lehigh Ponland Cement
Company, KVB, Inc., Irvine, CA, December 1984.
33. Annual Compliance Test: Mojave Plant, Pape & Steiner Environmental Services, Bakersfield,
CA, May 1985.
34. Stack Tests for Paniculate, SO2, NOX And Visible Emissions At Lone Star Florida Holding,
Inc., South Florida Environmental Services, Inc., West Palm Beach, FL, August 1985.
35. Compliance Stack Test At Lone Star Florida/Pennsuco, Inc., South Florida Environmental
Services, Inc., West Palm Beach, FL, July 1981.
11.6-24 EMISSION FACTORS 1/95
-------
36. Preliminary Stack Test At Lone Star Florida/Pennsuco, Inc., South Florida Environmental
Services, Inc., West Palm Beach, FL, July 1981.
37. Quarterly Testing For Lone Star Cement At Davensport, California, Pape & Steiner
Environmental Services, Bakersfield, CA, September 1985.
38. Written Communication from David S. Cahn, CalMat Co., El Monte, CA, to Frank Noonan,
U. S. Environmental Protection Agency, Research Triangle Park, NC, June 2, 1987.
39. Technical Report On The Demonstration Of The Feasibility OfNOx Emissions Reduction At
Riverside Cement Company, Crestmore Plant (Parts I-V), Riverside Cement Company,
Riverside, CA, and Quantitative Applications, Stone Mountain, GA, January 1986.
40. Emission Study Of The Cement Kiln No. 20 Baghouse Collector At The Alpena Plant, Great
Lakes Division, Lafarge Corporation, Clayton Environmental Consultants, Inc., Novi, MI,
March 1989.
41. Baseline And Solvent Fuels Stack Emissions Test At Alpha Portland Cement Company In
Cementon, New York, Energy & Resource Recovery Corp., Albany, NY, January 1982.
42. Stationary Source Sampling Report Of Lone Star Industries, New Orleans, Louisiana, Entropy
Environmentalists, Inc., Research Triangle Park, NC, May 1982.
43. Stationary Source Sampling Report Of Lone Star Industries, New Orleans, Louisiana, Entropy
Environmentalists, Inc., Research Triangle Park, NC, May 1982.
44. Source Emissions Survey Of Kiln No. 1 At Lone Star Industries, Inc., New Orleans,
Louisiana, Mullins Environmental Testing Company, Inc., Addison, TX, March 1984.
45. Written Communication from Richard Cooke, Ash Grove Cement West, Inc., Durkee, OR, to
Frank Noonan, U.S. Environmental Protection Agency, Research Triangle Park, NC,
May 13, 1987.
46. Source Emissions Survey Of Texas Cement Company OfBuda, Texas, Mullins Environmental
Testing Co., Inc., Addison, TX, September 1986.
47. Determination of Paniculate and Sulfur Dioxide Emissions From The Kiln And Alkali
Baghouse Stacks At Southwestern Portland Cement Company, Pollution Control Science, Inc.,
Miamisburg, OH, June 1986.
48. Written Communication from Douglas Maclver, Southwestern Portland Cement Company,
Victorville, CA, to John Croom, Quantitative Applications, Inc., Stone Mountain, GA,
October 23, 1989.
49. Source Emissions Survey Of Southwestern Portland Cement Company, KOSMOS Cement
Division, MetCo Environmental, Dallas, TX, June 1989.
50. Written Communication from John Mummert, Southwestern Portland Cement Company,
Amarillo, TX, to Bill Stewart, Texas Air Control Board, Austin, TX, April 14, 1983.
1/95 Mineral Products Industry 11.6-25
-------
51. Written Communication from Stephen Sheridan, Ash Grove Cement West, Inc., Portland,
OR, to John Croom, Quantitative Applications, Inc., Stone Mountain, GA, January 15, 1980.
52. Written Communication from David Cahn, CalMat Co., Los Angeles, CA, to John Croom,
Quantitative Applications, Inc., Stone Mountain, GA, December 18, 1989.
53. Source Emissions Compliance Test Report On The Kiln Stack At Marquette Cement
Manufacturing Company, Cape Girardeau, Missouri, Performance Testing & Consultants,
Inc., Kansas City, MO, February 1982.
54. Assessment Of Sulfur Levels At Lone Star Industries In Cape Girardeau, Missouri, KVB,
Ehnsford, NY, January 1984.
55. Written Communication from Douglas Maclver, Southwestern Portland Cement Company,
Nephi, UT, to Brent Bradford, Utah Air Conservation Committee, Salt Lake City, UT,
July 13, 1984.
56. Performance Guarantee Testing At Southwestern Portland Cement, Pape & Steiner
Environmental Services, Bakersfield, CA, February 1985.
57. Compliance Testing At Southwestern Portland Cement, Pape & Steiner Environmental
Services, Bakersfield, CA, April 1985.
58. Emission Tests On Quarry Plant No. 2 Kiln At Southwestern Portland Cement, Pape & Steiner
Environmental Services, Bakersfield, CA, March 1987.
59. Emission Tests On The No. 2 Kiln Baghouse At Southwestern Portland Cement, Pape &
Steiner Environmental Services, Bakersfield, CA, April 1987.
60. Compliance Stack Test Of Cooler No. 3 At Lone Star Florida, Inc., South Florida
Environmental Services, Inc., Belle Glade, FL, July 1980.
61. Stack Emissions Survey Of Lone Star Industries, Inc., Portland Cement Plant At Maryneal,
Texas, Ecology Audits, Inc., Dallas, TX, September 1979.
62. Emissions Testing Report Conducted At Kaiser Cement, Coupertino, California, For Kaiser
Cement, Walnut Creek, California, TMA Thermo Analytical, Inc., Richmond, CA, April 30,
1990.
63. Certification Of Compliance Stack Emission Test Program At Lone Star Industries, Inc., Cape
Girardeau, Missouri, April & June 1992, Air Pollution Characterization and Control, Ltd.,
Tolland, CT, January 1993.
64. Source Emissions Survey Of EssrockMaterials, Inc., Eastern Division Cement Group, Kilns
Number I And 2 Stack, Frederick, Maryland, Volume I (Draft), Metco Environmental,
Addison, TX, November 1991.
65. M. Branscome, et al., Evaluation Of Waste Combustion In A Dry-process Cement Kiln At
Lone Star Industries, Oglesby, Illinois, Research Triangle Institute, Research Triangle Park,
NC, December 1984.
11.6-26 EMISSION FACTORS 1/95
-------
11.7 Ceramic Products Manufacturing
11.7.1 General1'3
Ceramics are defined as a class of inorganic, nonmetallic solids that are subjected to high
temperature in manufacture and/or use. The most common ceramics are composed of oxides, carbides,
and nitrides. Silicides, borides, phosphides, tellurides, and selenides also are used to produce ceramics.
Ceramic processing generally involves high temperatures, and the resulting materials are heat resistant
or refractory.
Traditional ceramics refers to ceramic products that are produced from unrefined clay and
combinatioas of refined clay and powdered or granulated nonplastic minerals. Often, traditional
ceramics is used to refer to ceramics in which the clay content exceeds 20 percent. The general
classifications of traditional ceramics are described below.
Pottery is sometimes used as a generic term for ceramics that contain clay and are not used for
structural, technical, or refractory purposes.
Whiteware refers to ceramic ware that is white, ivory, or light gray in color after tiring.
Whiteware is further classified as earthenware, stoneware, chinaware, porcelain, and technical
ceramics.
Earthenware is defined as glazed or unglazed nonvitreous (porous) clay-based ceramic ware.
Applications for earthenware include artware, kitchenware, ovenware, tableware, and tile.
Stoneware is vitreous or semivitreous ceramic ware of fine texture, made primarily from
nonrefractory fire clay or some combination of clays, fluxes, and silica that, when fired, has properties
similar to stoneware made from fire clay. Applications for stoneware include artware, chemicalware,
cookware, drainpipe, kitchenware, tableware, and tile.
Chinaware is vitreous ceramic ware of zero or low absorption after firing that are used for
nontechnical applications. Applications for chinaware include artware, ovenware, sanitaryware, and
tableware.
Porcelain is defined as glazed or unglazed vitreous ceramic ware used primarily for technical
purposes. Applications for porcelain include artware, ball mill balls, ball mill liners, chemicalware,
insulators, and tableware.
Technical ceramics include vitreous ceramic whiteware used for such products as electrical
insulation, or for chemical, mechanical, structural, or thermal applications.
Ceramic products that are made from highly refined natural or synthetic compositions and
designed to have special properties are referred to as advanced ceramics. Advanced ceramics can be
classified according to application as electrical, magnetic, optical, chemical, thermal, mechanical,
biological, and nuclear.
7/96 Mineral Products 11.7-1
-------
Most ceramic products are clay-based and are made from a single clay or one or more clays
mixed with mineral modifiers such as quartz and feldspar. The types of commercial clays used for
ceramics are primarily kaolin and ball clay.
11.7.2 Process Description1'3"5
Figure 11.7-1 presents a general process flow diagram for ceramic products manufacturing.
The basic steps include raw material procurement, beneficiation, mixing, forming, green machining,
drying, presinter thermal processing, glazing, firing, final processing, and packaging. The following
paragraphs describe these operations in detail.
11.7.2.1 Raw Material Procurement -
To begin the process, raw materials are transported and stored at the manufacturing facility.
The raw materials used in the manufacture of ceramics range from relatively impure clay materials
mined from natural deposits to ultrahigh purity powders prepared by chemical synthesis. Naturally
occurring raw materials used to manufacture ceramics include silica, sand, quartz, flint, silicates, and
aluminosilicates (e. g., clays and feldspar).
11.7.2.2 Beneficiation -
The next step in the process is beneficiation. Although chemically synthesized ceramic
powders also require some beneficiation, the focus of this discussion is on the processes for
beneficiating naturally occurring raw materials. The basic beneficiation processes include
comminution, purification, sizing, classification, calcining, liquid dispersion, and granulation.
Naturally occurring raw materials often undergo some beneficiation at the mining site or at an
intermediate processing facility prior to being transported to the ceramic manufacturing facility.
Comminution entails reducing the particle size of the raw material by crushing, grinding, and
milling or fine grinding. The purpose of comminution is to liberate impurities, break up aggregates,
modify particle morphology and size distribution, facilitate mixing and forming, and produce a more
reactive material for firing. Primary crushing generally reduces material up to 0.3 meter (m) (1 foot
[ft]) in diameter down to 1 centimeter (cm) (0.40 inch [in.]) in diameter. Secondary crushing reduces
particle size down to approximately 1 millimeter (mm) (0.04 in.) in diameter. Fine grinding or milling
reduces the particle size down to as low as 1.0 micrometer (um) (4 x 10"5 in.) in diameter. Ball mills
are the most commonly used piece of equipment for milling. However, vibratory mills, attrition mills,
and fluid energy mills also are used. Crushing and grinding typically are dry processes; milling may
be a wet or dry process. In wet milling, water or alcohol commonly is used as the milling liquid.
Several procedures are used to purify the ceramic material. Water soluble impurities can be
removed by washing with deionized or distilled water and filtering, and organic solvents may be used
for removing water-insoluble impurities. Acid leaching sometimes is employed to remove metal
contaminants. Magnetic separation is used to extract magnetic impurities from either dry powders or
wet slurries. Froth flotation also is used to separate undesirable materials.
Sizing and classification separate the material into size ranges. Sizing is most often
accomplished using fixed or vibrating screens. Dry screening can be used to sizes down to 44 um
(0.0017 in., 325 mesh). Dry forced-air sieving and sonic sizing can be used to size dry powders down
to 37 um (0.0015 in., 400 mesh), and wet sieving can be used for particles down to 25 um
(0.00098 in., 500 mesh). Air classifiers generally are effective in the range of 420 um to 37 urn
11.7-2 EMISSION FACTORS 7/96
-------
BENEFICIATtON
> COMMINUTION-CRUSHING, QRINDINQ. AND MILUNQ OR RNE QRINDINQ (3-05-008-02)
» PURIFICATION-WASHING, ACID LEACHING, MAGNETIC SEPARATION, OR FROTH FLOTATION
• SIZINQ-VIBRATING SCREENS (3-05-008-10)
• CLASSIFICATION-AIR OR LIQUID CLASSIFIERS (3-05-OM-U)
> CALCINING (3-05-008-21,-22.-23.-24)
• LIQUID DISPERSION
• GRANULATION-DIRECT MIXING (3-05-006-05) OR SPRAY DRYING (3-05-008-10)
PROCESSING ADDITIVES-BINDERS.
PLASTICIZERS, DEFLOCCULANTS.
SURFACTANTS, ANTIFOAMING AGENTS
• EMISSIONS
Figure 11.7-1. Process flow diagram for ceramic products manufacturing.
(Source Classification Codes in parentheses.)
7/96
Mineral Products
11.7-3
-------
(0.017 to 0.0015 in., 40 to 400 mesh). However, special air classifiers are available for isolating
particles down to 10 urn (0.00039 in.).
Calcining consists of heating a ceramic material to a temperature well below its melting point
to liberate undesirable gases or other material and to bring about structural transformation to produce
the desired composition and phase product. Calcining typically is carried out in rotary calciners,
heated fluidized beds, or by heating a static bed of ceramic powder in a refractory crucible.
Liquid dispersion of ceramic powders sometimes is used to make slurries. Slurry processing
facilitates mixing and minimizes particle agglomeration. The primary disadvantage of slurry
processing is that the liquid must be removed prior to firing the ceramic.
Dry powders often are granulated to improve flow, handling, packing, and compaction.
Granulation is accomplished by direct mixing, which consists of introducing a binder solution during
powder mixing, or by spray drying. Spray dryers generally are gas-fired and operate at temperatures
of 110° to 130°C (230° to 270°F).
11.7.2.3 Mixing -
The purpose of mixing or blunging is to combine the constituents of a ceramic powder to
produce a more chemically and physically homogenous material for forming. Pug mills often are used
for mixing ceramic materials. Several processing aids may be added to the ceramic mix during the
mixing stage. Binders and plasticizers are used in dry powder and plastic forming; in slurry
processing, deflocculants, surfactants, and antifoaming agents are added to improve processing.
Liquids also are added in plastic and slurry processing.
Binders are polymers or colloids that are used to impart strength to green or unfired ceramic
bodies. For dry forming and extrusion, binders amount to 3 percent by weight of the ceramic mixture.
Plasticizers and lubricants are used with some types of binders. Plasticizers increase the flexibility of
the ceramic mix. Lubricants lower frictional forces between particles and reduce wear on equipment.
Water is the most commonly used liquid in plastic and slurry processing. Organic liquids such as
alcohols may also be used in some cases. Deflocculants also are used in slurry processing to improve
dispersion and dispersion stability. Surfactants are used in slurry processing to aid dispersion, and
antifoams are used to remove trapped gas bubbles from the slurry.
11.7.2.4 Forming -
In the forming step, dry powders, plastic bodies, pastes, or slurries are consolidated and
molded to produce a cohesive body of the desired shape and size. Dry forming consists of the
simultaneous compacting and shaping of dry ceramic powders in a rigid die or flexible mold. Dry
forming can be accomplished by dry pressing, isostatic compaction, and vibratory compaction.
Plastic molding is accomplished by extrusion, jiggering, or powder injection molding.
Extrusion is used in manufacturing structural clay products and some refractory products. Jiggering is
widely used in the manufacture of small, simple, axially symmetrical whiteware ceramic such as
cookware, fine china, and electrical porcelain. Powder injection molding is used for making small
complex shapes.
Paste forming consists of applying a thick film of ceramic paste on a substrate. Ceramic
pastes are used for decorating ceramic tableware, and forming capacitors and dielectric layers on rigid
substrates for microelectronics.
11.7-4 EMISSION FACTORS 7/96
-------
Slurry forming of ceramics generally is accomplished using slip casting, gelcasting, or tape
casting. In slip casting, a ceramic slurry, which has a moisture content of 20 to 35 percent, is poured
into a porous mold. Capillary suction of the mold draws the liquid from the mold, thereby
consolidating the cast ceramic material. After a fixed time the excess slurry is drained, and the cast is
dried. Slip casting is widely used in the manufacture of sinks and other sanitaryware, figurines,
porous thermal insulation, fine china, and structural ceramics with complex shapes. Gelcasting uses in
situ polymerization of organic monomers to produce a gel that binds ceramic particles together into
complex shapes such as turbine rotors. Tape casting consists of forming a thin film of ceramic slurry
of controlled thickness onto a support surface using a knife edge. Tape casting is used to produce thin
ceramic sheets or tape, which can be cut and stacked to form multilayer ceramics for capacitors and
dielectric insulator substrates.
11.7.2.5 Green Machining -
After forming, the ceramic shape often is machined to eliminate rough surfaces and seams or
to modify the shape. The methods used to machine green ceramics include surface grinding to smooth
surfaces, blanking and punching to cut the shape and create holes or cavities, and laminating for
multilayer ceramics.
11.7.2.6 Drying -
After forming, ceramics must be dried. Drying must be carefully controlled to strike a balance
between minimizing drying time and avoiding differential shrinkage, warping, and distortion. The
most commonly used method of drying ceramics is by convection, in which heated air is circulated
around the ceramics. Air drying often is performed in tunnel kilns, which typically use heat recovered
from the cooling zone of the kiln. Periodic kilns or dryers operating in batch mode also are used.
Convection drying also is carried out in divided tunnel dryers, which include separate sections with
independent temperature and humidity controls. An alternative to air drying is radiation drying in
which microwave or infrared radiation is used to enhance drying.
11.7.2.7 Presinter Thermal Processing -
Prior to firing, ceramics often are heat-treated at temperatures well below firing temperatures.
The purpose of this thermal processing is to provide additional drying, to vaporize or decompose
organic additives and other impurities, and to remove residual, crystalline, and chemically bound
water. Presinter thermal processing can be applied as a separate step, which is referred to as bisque
firing, or by gradually raising and holding the temperature in several stages.
11.7.2.S Glazing -
For traditional ceramics, glaze coatings often are applied to dried or bisque-fired ceramic ware
prior to sintering. Glazes consist primarily of oxides and can be classified as raw glazes or frit glazes.
In raw glazes, the oxides are in the form of minerals or compounds mat melt readily and act as
solvents for the other ingredients. Some of the more commonly used raw materials for glazes are
quartz, feldspars, carbonates, borates, and zircon. A frit is a prereacted glass. Frit manufacturing is
addressed in AP-42 Section 11.14.
To prepare glazes, the raw materials are ground in a ball mill or attrition mill. Glazes
generally are applied by spraying or dipping. Depending on their constituents, glazes mature at
temperatures of 600° to 1500°C (1110° to 2730°F).
11.7.2.9 Firing -
Firing is the process by which ceramics are thermally consolidated into a dense, cohesive body
comprised of tine, uniform grains. This process also is referred to as sintering or densification. In
7/96 Mineral Products 11.7-5
-------
general: (1) ceramics with fine particle size fire quickly and require lower firing temperatures;
(2) dense unfired ceramics fire quickly and remain dense after firing with lower shrinkage; and
(3) irregular shaped ceramics fire quickly. Other material properties that affect firing include material
surface energy, diffusion coefficients, fluid viscosity, and bond strength.
Parameters that affect firing include firing temperature, time, pressure, and atmosphere. A
short tiring time results in a product that is porous and has a low density; a short to intermediate firing
time results in fine-grained (i. e., having particles not larger than 0.2 millimeters), high-strength
products; and long firing times result in a coarse-grained products that are more creep resistant.
Applying pressure decreases firing time and makes it possihle to fire materials that are difficult to fire
using conventional methods. Oxidizing or inert atmospheres are used to fire oxide ceramics to avoid
reducing transition metals and degrading the finish of the product.
In addition to conventional firing, other methods used include pressure firing, hot forging,
plasma firing, microwave firing, and infrared firing. The following paragraphs describe conventional
and pressure firing, which are the methods used often.
Conventional firing is accomplished by heating the green ceramic to approximately two-thirds
of the melting point of the material at ambient pressure and holding it for a specified time in a
periodic or tunnel kiln. Periodic kilns are heated and cooled according to prescribed schedules. The
heat for periodic kilns generally is provided by electrical element or by firing with gas or oil.
Tunnel kilns generally have separate zones for cooling, firing, and preheating or drying. The
kilns may be designed so that (1) the air heated in the cooling zone moves into the firing zone and the
combustion gases in the firing zone are conveyed to the preheat/drying zone then exhausted, or (2) the
air heated in the cooling zone is conveyed to the preheat/drying zone and the firing zone gases are
exhausted separately. The most commonly used tunnel kiln design is the roller hearth (roller) kiln. In
conventional firing, tunnel kilns generally are fired with gas, oil, coal, or wood. Following firing and
cooling, ceramics are sometimes retired after the application of decals, paint, or ink.
Advanced ceramics often are fired in electric resistance-heated furnaces with controlled
atmospheres. For some products, separate furnaces may be needed to eliminate organic lubricants and
binders prior to firing.
Ceramic products also are manufactured by pressure firing, which is similar to the forming
process of dry pressing except that the pressing is conducted at the firing temperature. Because of its
higher costs, pressure firing is usually reserved for manufacturing ceramics that are difficult to tire to
high density by conventional firing.
11.7.2.10 Final Processing-
Following tiring, some ceramic products are processed further to enhance their characteristics
or to meet dimensional tolerances. Ceramics can be machined by abrasive grinding, chemical
polishing, electrical discharge machining, or laser machining. Annealing at high temperature, followed
by gradual cooling can relieve internal stresses within the ceramic and surface stresses due to
machining. In addition, surface coatings are applied to many fired ceramics. Surface coatings are
applied to traditional clay ceramics to create a stronger, impermeable surface and for decoration.
Coatings also may be applied to improve strength, and resistance to abrasion and corrosion. Coatings
can be applied dry, as slurries, by spraying, or by vapor deposition.
11.7-6 EMISSION FACTORS 7/96
-------
11.7.3 Emissions And Controls1'3'5'12'31
The primary pollutants associated with raw material beneficiation are particulate matter (PM)
and PM less than lOum in aerodynamic diameter (PM-10). Filterable PM and PM-10 are emitted
from comminution, sizing, classifying, handling, transfer, and storage. In addition, raw material
calciners emit filterable and condensible PM, which may include metals and other inorganic pollutants.
Calciners also emit products of combustion such as nitrogen oxides (NOX), sulfur oxides (SOX), carbon
monoxide (CO), carbon dioxide (CO2), and volatile organic compounds (VOC). Emissions of SOX are
a function of the sulfur content of the fuel used to fire the calciners and the sulfur content of the raw
materials used to manufacture ceramics. Emissions of VOC result from incomplete combustion and
volatilization of the organic material associated with the raw material. Other beneficiation processes
that are associated with emissions include acid leaching and granulation. Emissions of hydrochloric
acid (HC1) or other acids may arise from leaching. In addition, PM and products of combustion are
emitted from spray dryers used for granulation.
Mixing generally is a wet process. However, VOC emissions from this step may arise from
the volatilization of binders, plasticizers, and lubricants. Forming generally is performed in sealed
containers and often is a wet process; emissions from this step in the process are likely to be
negligible. However, tape casters are a source of VOC emissions. For ceramic bodies that are dry-
formed, PM is likely to be emitted from grinding, punching, and other green machining activities.
Particulate matter emissions consisting of metal and mineral oxides also arise from glaze
preparation, which includes mixing and grinding. Emissions of PM from glaze application also are
likely, if the glaze is applied by spraying.
Emissions associated from green ceramic heat treating processes, which include drying,
presinter thermal processing, and firing, include combustion products and filterable and condensible
PM. Particulate matter emissions consist in part of metals and the inorganic minerals associated with
the raw materials. Emissions of the products of combustion are a function of fuel type, raw material
coastituents, process temperature, and other operating parameters.
Emissions of fluorine compounds also are associated with firing. Fluorine is present in
ceramic raw materials in the range of 0.01 to 0.2 percent. As the temperature of green ceramic bodies
reaches 500° to 600°C (930° to 1110°F), the fluorine in the raw material forms hydrogen fluoride (HF)
and other fluorine compounds such as silicon tetrafluoride. Much of the fluorine is released as HF.
However, if lime is present in the ceramic body, HF reacts with the lime to form calcium fluoride
(CaF2), thereby reducing potential HF emissions.
Other emission sources associated with ceramics manufacturing include final processing
operations and fugitive dust sources. The final processing steps include grinding and polishing, which
can emit PM and PM-10, and surface coating, annealing, and chemical treatment, which can emit
VOC. Fugitive dust sources, which consist of vehicular traffic, wind erosion of storage piles, and
materials handling and transfer, emit PM and PM-10.
Several techniques have been used to control PM emissions from the mechanical processing of
ceramic raw materials and finished products. Fabric filters are the most commonly used control
device, but wet scrubbers and electrostatic precipitators (ESPs) also are used. Fabric filters, wet
scrubbers, and ESPs also are used to control emissions from clay calciners and dryers. Venturi
scrubbers and fabric filters are used to control emissions from granulation (spray dryers) and from
7/96 Mineral Products 11.7-7
-------
glaze preparation and application. Afterburners have been used to control VOC emissions from tape
casting operations. Emissions from kilns generally are uncontrolled.
Emissions of HF from kilns can be reduced through process modifications such as increasing
the raw material lime content and reducing kiln draft, kiln exhaust temperature, and kiln residence
time. Dry sorption scrubbing also has been used to control HF emissions in the brick and ceramic
industries in Germany and in the brick industry in the United States. These devices use limestone as a
sorption medium to produce CaF2, which is removed by means of a rotating screen, drum, or fabric
filter. Control efficiencies of 95 to 99 percent have been reported for this type of scrubber.
Table 11.7-1 presents emission factors for PM and lead emissions from various ceramic
products manufacturing processes. Table 11.7.2 present emission factors for SO2, NOX, CO, CO2,
VOC, HF, and fluoride emissions from ceramic kilns and tape casters.
11.7-8 EMISSION FACTORS 7/96
-------
Table 11.7-1. EMISSION FACTORS FOR CERAMIC PRODUCTS
MANUFACTURING OPERATIONS3
Source
Comminution-raw material crushing and
screening line with fabric filter0
(SCC 3-05-008-02)
Dryerd
(SCC 3-05-008-13)
Coolerd
(SCC 3-05-008-58)
Granulation-natural gas-fired spray dryer
(SCC 3-05-008-10)
with fabric filter6
with venturi scrubbed
Firing-natural gas-fired kilng
(SCC 3-05-008-50)
Retiring-natural gas-fired kilnh
(SCC 3-05-008-56)
Ceramic glaze spray booth
(SCC 3-05-008-45)
uncontrolledJ
with wet scrubber^
Filterable
PM (lb/ton)b
0.12
2.3
0.11
0.060
0.19
0.49
0.067
19
1.8
EMISSION
FACTOR
RATING
D
E
E
E
D
D
E
E
D
Lead
(Ib/ton)
ND
ND
ND
ND
ND
ND
ND
3.0
ND
EMISSION
FACTOR
RATING
NA
NA
NA
NA
NA
NA
NA
E
NA
a Emission factor units are Ib of pollutant per ton of fired ceramic produced, unless noted. To convert
from Ib/ton to kg/Mg, multiply by 0.5. Factors represent uncontrolled emissions unless noted. SCC
= Source Classification Code. ND = no data. NA = not applicable.
b Filterable PM is that PM collected on the front-half of an EPA Method 5 (or equivalent) sampling
train. Although condensible organic and inorganic PM emissions are expected from dryers and
kilns, no data are available to estimate these emissions.
c References 12-13. Raw material processing for production of quarry tile, which is an unglazed file
product similar to structural clay products. Emission factor units are Ib of pollutant per ton of
material processed.
d Reference 15.
e Reference 16. Emission factor units are Ib of pollutant per ton of dry material produced.
f References 26-29. Emission factor units are Ib of pollutant per ton of dry material produced.
8 References 7,9-11,15,23-25.
h Reference 6. Kiln is used for refiring tile after application of decals, paint, or ink screening.
J Reference 30. Emission factor units are Ib of pollutant per ton of glazed used. Glaze contains
about 24 percent lead oxide.
k References 20-22. Emission factor units are Ib of pollutant per ton of glaze used.
7/96
Mineral Products
11.7-9
-------
Table 11.7-2. EMISSION FACTORS FOR GASEOUS POLLUTANT EMISSIONS FROM
CERAMIC PRODUCTS MANUFACTURING3
EMISSION FACTOR RATING: E
Source
Firing— natural gas-fired kiln
(SCC 3-05-008-50)
Retiring-natural gas-fired
kilnk
(SCC 3-05-008-56)
Forming—tape casters"1
(SCC 3-05-008-31)
SO2
44 -Se
ND
ND
NOX
0.54f
ND
ND
CO
3.38
ND
ND
C02
780f
97
ND
vocb
0.438
ND
58
HF°
0.46h
ND
ND
Fluoridesd
0.56>
0.019
ND
a Emission factor units are Ib of pollutant per ton of ceramic product produced, unless noted. To
convert from Ib/ton to kg/Mg, multiply by 0.5. Factors represent uncontrolled emissions unless
noted. SCC = Source Classification Code. ND = no data.
b VOC reported on an "as propane" basis; measured using EPA Method 25A. Emission factor may
include nonphotochemically reactive compounds that are not considered VOC. No data are
available to estimate emissions of these non-VOC compounds.
c Hydrogen fluoride measured using EPA Method 26A. This compound is listed as a hazardous air
pollutant under Section 112(b) of the Clean Air Act, as amended in November 1990. A mass
balance on flouride will provide a better estimate of HF emissions for individual facilities.
d Total fluorides measured during EPA Method 13A or 13B. Measurements include HF and other
fluorine compounds. A mass balance on flouride will provide a better estimate of fluoride
emissions for individual facilities.
e Reference 10. For facilities using raw material with a sulfur content greater than 0.07 percent. The
variable S represents the raw material sulfur content (percent). For facilities using raw material with
a sulfur content less than or equal to 0.07 percent, use 9.5-S Ib/ton to estimate emissions
(References 9,11). Emissions of SO2 are dependent on the sulfur content of the raw material and
the fuel used to fire the kiln.
References 9,11,15. EMISSION FACTOR RATING: D.
Reference 15. EMISSION FACTOR RATING: D.
Reference 15.
References 7,9-11, 23-25.
k Reference 6.
m Reference 14. Emission factor units are Ib of pollutant per ton of formed product. Emissions
controlled by an afterburner.
References For Section 11.7
1. Kirk-Othmer Encyclopedia Of Chemical Technology, Fourth Edition, Volume 5, John Wiley &
Sons, New York, 1992.
2. 1987 Census Of Manufactures, U. S. Department of Commerce, Washington, D.C., May 1990.
3. Ullman's Encyclopedia Of Industrial Chemistry, Fifth Edition, Volume A6.
11.7-10
EMISSION FACTORS
7/96
-------
4. D. W. Richerson, Modern Ceramic Engineering: Properties Processing, And Use In Design,
Marcel Dekker, Inc., New York, NY, 1982.
5. P. Vincenzini (ed.), Fundamentals Of Ceramic Engineering, Elsevier Science Publishers, Ltd.,
New York, 1991.
6. Paniculate Emission Testing For Florida Tile Corporation, Lawrenceburg, Kentucky,
March 7-8, 1989, Air Systems Testing, Inc., Marietta, GA, April 1989.
7. Paniculate Emission Testing For Florida Tile Corporation, Lawrenceburg, Kentucky, April 19,
1989, Air Systems Testing, Inc., Marietta, GA, May 1989.
8. Source Emission Tests At Stark Ceramics, Inc., East Canton, Ohio, No. 3 Kiln Stack,
September 16, 1993, Custom Stack Analysis Company, Alliance, OH, October 1993.
9. Metropolitan Ceramics, Canton, Ohio, Tunnel Kiln #3 Exhaust Stack, Paniculate, SO2, NOV
Hydrofluoric Acid Emission Evaluation, Conducted - November 17-18, 1993, Envisage
Environmental Incorporated, Richfield, OH, December 16, 1993.
10. Metropolitan Ceramics, Inc., Canton, Ohio, TK1, TK2, TK3 Exhausts, Paniculate, Sulfur
Dioxides, & Fluorides Emission Evaluation, Conducted - March 30 & April 14, 1994,
Envisage Environmental Incorporated, Richfield, OH, May 9, 1994.
11. Source. Evaluation Results, U. S. Ceramic Tile Company, East Sparta, Ohio, August 11, 1993,
Envisage Environmental Incorporated, Richfield, OH, September 1, 1993.
12. Paniculate Emissions Test For American Olean Tile Company, Fayette, AL, Crushing And
Screening Line #1, October 15, 1991, Pensacola POC, Inc., Pensacola, FL, October 1991.
13. Paniculate Emissions Test For American Olean Tile Company, Fayette, AL, Crushing And
Screening Line #2, October 16, 1991, Pensacola POC, Inc., Pensacola, FL, October 1991.
14. VOC Emission Test Repon For GE Ceramics Tape Casters Fume Oxidizer, Chattanooga, TN,
September 13-15, 1989, IT-Air Quality Services Group, Knoxville, TN, October, 1989.
15. Exhaust Emission Sampling For Nonon Company, Soddy-Daisy, TN, April 19-20, 1994,
Armstrong Environmental, Inc., Dallas, TX, April 1994.
16. Paniculate Emission Evaluation For Steward, Inc., Chattanooga, TN, March 30, 1993, FBT
Engineering and Environmental Services, Chattanooga, TN, May 1993.
17. D. Brosnan, "Technology and Regulatory Consequences of Fluorine Emissions in Ceramic
Manufacturing", American Ceramic Industry Bulletin, 71 (12), pp 1798-1802, The American
Ceramic Society, Westerville, OH, December 1992.
18. Calciners And Dryers In The Mineral Industries-Background Information For Proposed
Standards, EPA-450/3-85-025a, U. S. Environmental Protection Agency, Research Triangle
Park, NC, October 1985.
7/96 Mineral Products 11.7-11
-------
19. C. Palmonari and G. Timellini, Pollutant Emission Factors For The Ceramic Floor And Wall
Tile Industry, Journal of the Air Pollution Control Association, Volume 32, No. 10, Pittsburgh,
PA, October 1982.
20. Report To American Standard On Stack Paniculate Samples Collected At Tiffin, OH (Test
Date August 18, 1992), Affiliated Environmental Services, Inc., Sandusky, OH, August 24,
1992.
21. Report To American Standard On Stack Paniculate Samples Collected At Tiffin, OH (Test
Date August 19, 1992), Affiliated Environmental Services, Inc., Sandusky, OH, August 24,
1992.
22. Report To American Standard On Stack Paniculate Samples Collected At Tiffin, OH (Test
Date February 8, 1994), Affiliated Environmental Services, Inc., Sandusky, OH, February 15,
1994.
23. Emission Test Report-Plant A, Roller Kiln, May 1994, Document No. 4602-01-02,
Confidential Business Information Files, Contract No 68-D2-0159, Assignment No. 2-01, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.
24. Emission Test Report (Excerpts)-Plant A, Roller Kiln, June 1993, Document No. 4602-01-02,
Confidential Business Information Files, Contract No 68-D2-0159, Assignment No. 2-01, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.
25. Emission Test Report (Excerpts)-Plant A, Roller Kiln, February 1992, Document
No. 4602-01-02, Confidential Business Information Files, Contract No 68-D2-0159,
Assignment No. 2-01, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 8, 1995.
26. Emission Test Report-Plant A, Spray Dryer, October 1994, Document No. 4602-01-02,
Confidential Business Information Files, Contract No 68-D2-0159, Assignment No. 2-01, U. S.
Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.
27. Emission Test Report (Excerpts)-Plant A, Spray Dryer, April 1994, Document
No. 4602-01-02, Confidential Business Information Files, Contract No 68-D2-0159,
Assignment No. 2-01, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 8, 1995.
28. Emission Test Report (Excerpts)-Plant A, Spray Dryer, January 1993, Document
No. 4602-01-02, Confidential Business Information Files, Contract No 68-D2-0159,
Assignment No. 2-01, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 8, 1995.
29. Emission Test Report (Excerpts)-Plant A, Spray Dryer, February 1992, Document
No. 4602-01-02, Confidential Business Information Files, Contract No 68-D2-0159,
Assignment No. 2-01, U. S. Environmental Protection Agency, Research Triangle Park, NC,
June 8, 1995.
11.7-12 EMISSION FACTORS 7/96
-------
30. Stationary Source Sampling Report Reference No. 6445, Lead And Paniculate Emissions
Testing, Spray Booth 2A Stack, Entropy Environmentalists, Inc., Research Triangle Park, NC,
September 20, 1989.
31. Emission Factor Documentation For AP-42 Section 11.7, Ceramic Products Manufacturing,
Final Report, EPA Contract No. 68-D2-0159, Midwest Research Institute, Gary, NC, June
1996.
7/96 Mineral Products 11.7-13
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11.8 Clay And Fly Ash Sintering
NOTE: Clay and fly ash sintering operations are no longer conducted in the
United States. However, this section is being retained for historical
purposes.
11.8.1 Process Description1"3
Although the process for sintering fly ash and clay are similar, there are some distinctions that
justify a separate discussion of each process. Fly ash sintering plants are generally located near the
source, with the fly ash delivered to a storage silo at the plant. The dry fly ash is moistened with a
water solution of lignin and agglomerated into pellets or balls. This material goes to a traveling-grate
sintering machine where direct contact with hot combustion gases sinters the individual particles of
the pellet and completely burns off the residual carbon in the fly ash. The product is then crushed,
screened, graded, and stored in yard piles.
Clay sintering involves the driving off of entrained volatile matter. It is desirable that the
clay contain a sufficient amount of volatile matter so that the resultant aggregate will not be too
heavy. It is thus sometimes necessary to mix the clay with finely pulverized coke (up to 10 percent
coke by weight). In the sintering process, the clay is first mixed with pulverized coke, if necessary,
and then pelletized. The clay is next sintered in a rotating kiln or on a traveling grate. The sintered
pellets are then crushed, screened, and stored, in a procedure similar to that for fly ash pellets.
11.8.2 Emissions And Controls1
In fly ash sintering, improper handling of the fly ash creates a dust problem. Adequate
design features, including fly ash wetting systems and paniculate collection systems on all transfer
points and on crushing and screening operations, would greatly reduce emissions. Normally, fabric
filters are used to control emissions from the storage silo, and emissions are low. The absence of this
dust collection system, however, would create a major emission problem. Moisture is added at the
point of discharge from silo to the agglomerator, and very few emissions occur there. Normally,
there are few emissions from the sintering machine, but if the grate is not properly maintained, a dust
problem is created. The consequent crushing, screening, handling, and storage of the sintered
product also create dust problems.
In clay sintering, the addition of pulverized coke presents an emission problem because the
sintering of coke-impregnated dry pellets produces more particulate emissions than the sintering of
natural clay. The crushing, screening, handling, and storage of the sintered clay pellets creates dust
problems similar to those encountered in fly-ash sintering. Emission factors for both clay and fly-ash
sintering are shown in Tables 11.8-1 and 11.8-2.
2/72 (Reformatted 1/95) Mineral Products Industry 11.8-1
-------
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11.8-2
EMISSION FACTORS
(Reformatted 1/95) 2/72
-------
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-------
References For Section 11.8
1. Air Pollutant Emission Factors, Final Report, Resources Research, Inc., VA, prepared for
National Air Pollution Control Administration, Durham, NC, under Contract
No. PA-22-68-119, April 1970.
2. Communication between Resources Research, Inc., Reston, VA, and a clay sintering firm,
October 2, 1969.
3. Communication between Resources Research, Inc., Reston, VA, and an anonymous air
pollution control agency, October 16, 1969.
4. J. J. Henn, et al., Methods For Producing Alumina From Clay: An Evaluation Of Two Lime
Sinter Processes, U. S. Bureau Of Mines, Department Of Interior, Washington, DC, Report of
Investigation No. 7299, September 1969.
5. F. A. Peters, et al., Methods For Producing Alumina From Clay: An Evaluation Of The Lime-
Soda Sinter Process, U. S. Bureau Of Mines, Department Of Interior, Washington, DC, Report
of Investigation No. 6927, 1967.
H.8-4 EMISSION FACTORS (Reformatted 1/95) 2/72
-------
11.9 Western Surface Coal Mining
11.9 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, coal, or equipment,
or exposure of credible 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 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 is for a single dust-generating activity, such as
vehicle traffic on unpaved roads. The predictive equation explains much of the observed variance in
emission factors by relating emissions to 3 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).
The equations may be used to estimate particulate emissions generated per unit of source
extent (e. g., vehicle distance traveled or mass of material transferred). The equations were
9/88 (Reformatted 1/95) Mineral Products Industry 11.9-1
-------
COAL TYPE
LIGNITE
SUBBITUMINOUS CZJ
BITUMINOUS
l
2
3
A
5
6
7
8
9
10
11
12
Coal field
Fort Union
Powder River
North Central
Bighorn Basin
Wind River
Buns Fork
Uinta
Southwestern Utah
San Juan River
Raton Mesa
Denver
Greac River
Scrippable reserves
(1Q6 tons)
23,529
56,727
All underground
Ali underground
3
1,000
30S
224
2,318
All underground
All underground
2,120
Figure 11.9-1. Coal fields of the western United States.
11.9-2
EMISSION FACTORS
(Reformatted 1/95) 9/88
-------
1
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11.9-4
EMISSION FACTORS
(Reformatted 1/95) 9/88
-------
Ml
ra
w
to
S
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9/88 (Reformatted 1/95) Mineral Products Industry 11.9-5
-------
V)
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11.9-6
EMISSION FACTORS
(Reformatted 1/95) 9/88
-------
CD
.a
va
a.
IT)
IN
VI
o §
'£ g
il
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111
9/88 (Reformatted 1/95) Mineral Products Industry 11.9-7
-------
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 ranges 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.
Table 11.9-3 (Metric And English Units). TYPICAL VALUES FOR CORRECTION FACTORS
APPLICABLE TO THE PREDICTIVE EMISSION FACTOR EQUATIONS2
Source
Coal loading
Bulldozers
Coal
Overburden
Dragline
Scraper
Grader
Light/Medium duty
vehicle
Haul truck
Correction Factor
Moisture
Moisture
Silt
Moisture
Silt
Drop distance
Drop distance
Moisture
Silt
Weight
Weight
Speed
Speed
Moisture
Wheels
Silt loading
Silt loading
Number Of
Test
Samples
7
3
3
8
8
19
19
7
10
15
15
7
7
29
26
26
Range
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
0.9- 1.70
6.1 - 10.0
3.8 - 254
34 - 2270
Geometric
Mean
17.8
10.4
8.6
7.9
6.9
8.6
28.1
3.2
16.4
48.8
53.8
11.4
7.1
1.2
8.1
40.8
364
Units
%
%
%
%
%
m
ft
%
%
Mg
ton
kph
mph
%
number
g/m2
Ib/acre
a Reference 1.
11.9-8
EMISSION FACTORS
(Reformatted 1/95) 9/88
-------
DH
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9/88 (Reformatted 1/95)
Mineral Products Industry
11.9-9
-------
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11.9-10
EMISSION FACTORS
(Reformatted 1/95) 9/88
-------
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, 2 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 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. Table 11.9-3
lists measured properties of aggregate materials that can be used to estimate correction parameter
values for the predictive emission factor equations in Chapter 13, in the event that site-specific values
are not available. Use of mean correction parameter values from Table 11.9-3 will reduce the quality
ratings of the emission factor equations in Chapter 13 by 1 level.
9/88 (Reformatted 1/95) Mineral Products Industry 11.9-11
-------
I
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-------
Table 11.9-6 (English Units). OPERATING CHARACTERISTICS OF THE COAL MINES
REFERRED TO IN TABLE 11.9-4a
Parameter
Production rate
Coal transport
Stratigraphic
data
Coal analysis
data
Surface
disposition
Storage
Blasting
Required Information
Coal mined
Avg. unit train frequency
Overburden thickness
Overburden density
Coal seam thicknesses
Parting thicknesses
Spoils bulking factor
Active pit depth
Moisture
Ash
Sulfur
Heat content
Total disturbed land
Active pit
Spoils
Reclaimed
Barren land
Associated disturbances
Capacity
Frequency, total
Frequency, overburden
Area blasted, coal
Area blasted, overburden
Units
106 ton/yr
per day
ft
lb/yd3
ft
ft
%
ft
%
%, wet
%, wet
Btu/lb
acre
acre
acre
acre
acre
acre
ton
per week
per week
ft2
ft2
I
1.13
NA
21
4000
9,35
50
22
52
10
8
0.46
11000
168
34
57
100
—
12
NA
4
3
16000
20000
II
5.0
NA
80
3705
15,9
15
24
100
18
10
0.59
9632
1030
202
326
221
30
186
NA
4
0.5
40000
—
Mine
III
9.5
2
90
3000
27
NA
25
114
24
8
0.75
8628
2112
87
144
950
455
476
IV
3.8
NA
65
—
2,4,8
32,16
20
80
38
7
0.65
8500
1975
—
—
—
—
—
V
12.0b
2
35
—
70
NA
—
105
30
6
0.48
8020
217
71
100
100
—
46
— NA 48000
3
3
—
—
7
NA
30000
NA
7b
7b
—
—
a Reference 4.
b Estimate.
NA = not applicable. Dash = no data.
References For Section 11.9
1. K. Axetell and C. Cowherd, Improved Emission Factors For Fugitive Dust From Western
Surface Coal Mining Sources, 2 Volumes, EPA Contract No. 68-03-2924, U. S.
Environmental Protection Agency, Cincinnati, OH, July 1981.
9/88 (Reformatted 1/95)
Mineral Products Industry
11.9-13
-------
2. Reserve Base Of U. S. Coals By Sulfur Content: Part 2, The Western States, IC8693, Bureau
Of Mines, U. S. Department Of The Interior, Washington, DC, 1975.
3. Bituminous Coal And Lignite Production And Mine Operations -1978, DOE/EIA-0118(78),
U. S. Department of Energy, Washington, DC, June 1980.
4. K. Axetell, Survey Of Fugitive Dust From Coal Mines, EPA-908/1-78-003, U. S.
Environmental Protection Agency, Denver, CO, February 1978.
5. D. L. Shearer, et al., Coal Mining Emission Factor Development And Modeling Study, Amax
Coal Company, Carter Mining Company, Sunoco Energy Development Company, Mobil Oil
Corporation, and Atlantic Richfield Company, Denver, CO, July 1981.
H.9-14 EMISSION FACTORS (Reformatted 1/95) 9/88
-------
11.10 Coal Cleaning
11.10.1 Process Description1"2'9
Coal cleaning is a process by which impurities such as sulfur, ash, and rock are removed
from coal to upgrade its value. Coal cleaning processes are categorized as either physical cleaning or
chemical cleaning. Physical coal cleaning processes, the mechanical separation of coal from its
contaminants using differences in density, are by far the major processes in use today. Chemical coal
cleaning processes are currently being developed, but their performance and cost are undetermined at
this time. Therefore, chemical processes are not included in this discussion.
The scheme used in physical coal cleaning processes varies among coal cleaning plants but
can generally be divided into four basic phases: initial preparation, fine coal processing, coarse coal
processing, and final preparation. A process flow diagram for a typical coal cleaning plant is
presented in Figure 11.10-1.
In the initial preparation phase of coal cleaning, the raw coal is unloaded, stored, conveyed,
crushed, and classified by screening into coarse and fine coal fractions. The size fractions are then
conveyed to their respective cleaning processes.
Fine coal processing and coarse coal processing use similar operations and equipment to
separate the contaminants. The primary difference is the severity of operating parameters. The
majority of coal cleaning processes use upward currents or pulses of a fluid such as water to fluidize
a bed of crushed coal and impurities. The lighter coal particles rise and are removed from the top of
the bed. The heavier impurities are removed from the bottom. Coal cleaned in the wet processes
then must be dried in the final preparation processes.
Final preparation processes are used to remove moisture from coal, thereby reducing freezing
problems and weight and raising the heating value. The first processing step is dewatering, in which
a major portion of the water is removed by the use of screens, thickeners, and cyclones. The second
step is normally thermal drying, achieved by any one of three dryer types: fluidized bed, flash, and
multilouvered. In the fluidized bed dryer, the coal is suspended and dried above a perforated plate by
rising hot gases. In the flash dryer, coal is fed into a stream of hot gases for instantaneous drying.
The dried coal and wet gases are both drawn up a drying column and into a cyclone for separation.
In the multilouvered dryer, hot gases are passed through a falling curtain of coal, which is then raised
by flights of a specially designed conveyor.
11.10.2 Emissions And Controls1'2'9'10
Emissions from the initial coal preparation phase of either wet or dry processes consist
primarily of fugitive particulate matter (PM) as coal dust from roadways, stock piles, refuse areas,
loaded railroad cars, conveyor belt pouroffs, crushers, and classifiers. The major control technique
used to reduce these emissions is water wetting. Another technique that applies to unloading,
conveying, crushing, and screening operations involves enclosing the process area and circulating air
from the area through fabric filters. Uncontrolled emission factors for various types of fugitive
sources in coal cleaning facilities can be developed from the equations found in Section 13.2,
"Fugitive Dust Sources".
11/95 Coal Cleaning 11.10-1
-------
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EMISSION FACTORS
11/95
-------
The major emission source in the fine or coarse coal processing phases is the air exhaust from
the air separation processes (air tables). For the dry cleaning process, these emissions are generated
when the coal is stratified by pulses of air. Paniculate matter emissions from this source are
normally controlled with cyclones followed by fabric filters. Potential emissions from wet cleaning
processes are very low.
The major source of emissions from the final preparation phase is the thermal dryer exhaust.
This emission stream contains coal particles entrained in the drying gases and volatile organic
compounds (VOC) released from the coal, in addition to the standard products of coal combustion
resulting from burning coal to generate the hot gases (including carbon monoxide [CO], carbon
dioxide [CO2], VOC, sulfur dioxide [SO2], and nitrogen oxides [NOX]). Table 11.10-1 shows
emission factors for PM. Emission factors for S02, NOX, VOC, and CO2 are presented in
Table 11.10-2. The most common technology used to control dryer emissions is venturi scrubbers
and mist eliminators downstream from the product recovery cyclones. The control efficiency of these
techniques for filterable PM ranges from 98 to 99.9 percent. Scrubbers also may achieve between 0
and 95 percent control of SO2 emissions. The use of a neutralizing agent (such as NaOH) in the
scrubber water increases the SO2 removal efficiency of the scrubber.
A number of inorganic hazardous air pollutants are found in trace quantities in coal. These
include arsenic, beryllium, cadmium, chromium, copper, mercury, manganese, nickel, lead, thorium,
and uranium. It is likely that many of these are emitted in trace amounts from crushing, grinding,
and drying operations.
The new source performance standards (NSPS) for coal preparation plants were promulgated
in January 1976 (40 CFR Subpart Y). These standards specify emission limits for PM from coal
cleaning thermal dryers and pneumatic cleaning equipment sources, and opacity limits for fugitive
emissions from coal processing and conveying equipment, coal storage systems, and coal transfer and
loading systems.
11/95 Coal Cleaning 11.10-3
-------
Table 11.10-1. PM EMISSION FACTORS FOR COAL CLEANING*
EMISSION FACTOR RATING: D (except as noted)
Process
Multilouvered dryer
(SCC 3-05-010-03)
Fluidized bed dryer6
(SCC 3-05-010-01)
Fluidized bed dryer with venturi
scrubber"
(SCC 3-05-010-01)
Fluidized bed dryer with venturi scrubber
and tray scrubber*
(SCC 3-05-010-01)
Air tables with fabric filter"1
(SCC 3-05-010-13)
Filterable PMb
PM
3.7
26f
0.17
0.025
0.032"
PM-2.5
ND
3.88
ND
ND
ND
PM-1.0
ND
1.1*
ND
ND
ND
Condensible PMC
Inorganic
0.057
0.034h
0.043
ND
0.033P
Organic
0.018
0.0075h
0.0048
ND
0.00261
a Emission factor units are Ib/ton of coal feed, unless noted. 1 Ib/ton = 2 kg/Mg. SCC =
Source Classification Code. ND = no data.
b
Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or
equivalent) sampling train.
0 Condensible PM is that PM collected in the impinger portion of a PM sampling train.
d Reference 11. Alternate SCC is 3-05-310-03, which corresponds to units of Ib/thousand tons
of coal feed. To determine the emission factor for this alternate SCC, multiply the factor in
this table by 1,000.
e Alternate SCC is 3-05-310-01, which corresponds to units of Ib/thousand tons of coal feed.
To determine the emission factor for this alternate SCC, multiply the factor in this table by
1,000.
f References 12,15.
g References 12,15. EMISSION FACTOR RATING: E. Particle size data from Reference 15
used in conjunction with filterable PM data from References 12 and 15. Actual cut size of
PM-2.5 data was 2.7 microns.
h Reference 12.
J References 12-13,15-16,20. See footnote "e" above for alternate SCC.
k Reference 21. Tray scrubber using NaOH as the scrubbing liquid. See footnote "e" above
for alternate SCC.
m Alternate SCC is 3-05-310-13, which corresponds to units of Ib/thousand tons of coal feed.
To determine the emission factor for this alternate SCC, multiply the factor in this table by
1,000.
" References 18-19.
p Reference 19.
q Reference 18.
11.10-4
EMISSION FACTORS
11/95
-------
Table 1 1 . 10-2. GASEOUS POLLUTANT EMISSION FACTORS
FOR COAL CLEANING8
EMISSION FACTOR RATING: D (except as noted)
Process
Multilouvered dryer6
(SCC 3-05-010-03)
Fluidized bed dryerd
(SCC 3-05-010-01)
Fluidized bed dryer with venturi scrubber11
(SCC 3-05-010-01)
Fluidized bed dryer with venturi scrubber
and tray scrubber1"
(SCC 3-05-010-01)
vocb
ND
ND
0.098*
ND
SO2
ND
1.4e
k
0.072"
NOX
ND
O.l6f
0.16f
0.16f
CO2
160
308
3QS
30S
1 Ib/ton = 2 kg/Mg.
Measurement may
a Emission factor units are Ib/ton of coal feed, unless noted.
SCC = Source Classification Code. ND = no data.
b VOC as methane, measured with an EPA Method 25A sampling train.
include compounds designated as nonreactive.
c Reference 11. EMISSION FACTOR RATING: E. Alternate SCC is 3-05-310-03, which
corresponds to units of Ib/thousand tons of coal feed. To determine the emission factor for
this alternate SCC, multiply the factor in this table by 1,000.
d Alternate SCC is 3-05-310-01, which corresponds to units of Ib/thousand tons of coal feed.
To determine the emission factor for this alternate, SCC, multiply the factor in this table by
1,000.
e References 12,14,17. EMISSION FACTOR RATING: E.
f References 12,14,21.
not expected to provide control of NOX emissions.
g References 12-16,20. Includes CO2 measurements before and after control devices that are
not expected to provide control of CO2 emissions.
h See footnote "d" above for alternate SCC.
J References 13-14.
k Venturi scrubbers may achieve between 0 and 95% control of SO2 emissions. The use of a
neutralizing agent in the scrubber water increases the SO^ control efficiency.
m Venturi scrubber followed by tray scrubber using a NaOH solution as the scrubbing liquid.
See footnote "d" above for alternate SCC.
n Reference 21.
Includes NOX measurements before and after control devices that are
11/95
Coal Cleaning
11.10-5
-------
References For Section 11.10
1. Background Information For Establishment Of National Standards Of Performance For New
Sources: Coal Cleaning Industry, EPA Contract No. CPA-70-142, Environmental
Engineering, Inc., Gainesville, FL, July 1971.
2. Air Pollutant Emissions Factors, Contract No. CPA-22-69-119, Resources Research Inc.,
Reston, VA, April 1970.
3. Stack Test Results On Thermal Coal Dryers (Unpublished), Bureau Of Air Pollution Control,
Pennsylvania Department Of Health, Harrisburg, PA.
4. "Amherst's Answer To Air Pollution Laws", Coal Mining And Processing, 7(2):26-29,
February 1970.
5. D. W. Jones, "Dust Collection At Moss No. 3", Mining Congress Journal, 55(7):53-56,
July 1969.
6. E. Northcott, "Dust Abatement At Bird Coal", Mining Congress Journal, 53:26-29,
November 1967.
7. Background Information For Standards Of Performance: Coal Preparation Plants, Volume 2:
Test Data Summary, EPA-450/2-74-021b, U. S. Environmental Protection Agency, Research
Triangle Park, NC, October 1974.
8. Estimating Air Toxic Emissions From Coal And Oil Combustion Sources, EPA-450/2-89-001,
U. S. Environmental Protection Agency, Research Triangle Park, NC, April 1989.
9. Second Review Of New Source Performance Standards For Coal Preparation Plants,
EPA-450/3-88-001, U. S. Environmental Protection Agency, Research Triangle Park, NC,
February 1988.
10. Estimating Air Toxic Emissions From Coal and Oil Combustion Sources, EPA-450/2-89-001,
U.S. Environmental Protection Agency, Research Triangle Park, NC, April 1989.
11. Emission Testing Report: Bureau Of Mines, Grand Forks, North Dakota, EMB
Report 73-CCL-5, U. S. Environmental Protection Agency, Research Triangle Park, NC,
April 1973.
12. Coal Preparation Plant Emission Tests, Consolidation Coal Company, Bishop, West Virginia,
EMB Report 72-CCL-19A, U. S. Environmental Protection Agency, Research Triangle Park,
NC, February 1972.
13. Coal Preparation Plant Emission Tests, Westmoreland Coal Company, Wentz Plant, EMB
Report 72-CCL-22, U. S. Environmental Protection Agency, Research Triangle Park, NC,
April 1972.
14. Emission Test Report, U.S. Steel #50, Pineville, West Virginia, EMB Report 73-CCL-l, U. S.
Environmental Protection Agency, Research Triangle Park, NC, September 1972.
11.10-6 EMISSION FACTORS 11195
-------
15. Emission Test Report, Westmoreland Coal Company, Quinwood, West Virginia, EMB
Report 75-CCL-7, U. S. Environmental Protection Agency, Research Triangle Park, NC,
May 1976.
16. Coal Preparation Plant Emission Tests: Consolidation Coal Company, Bishop, West Virginia,
EMB Report 73-CCL-19, U.S. Environmental Protection Agency, Research Triangle Park,
NC, November 1972.
17. Report By York Research Corporation On Emissions From The Island Creek Coal Company
Coal Processing Plant, Vansant, Virginia, EMB Report 72-CCL-6, U.S. Environmental
Protection Agency, Research Triangle Park, NC, February 1972.
18. Report By York Research Corporation On Emissions From The Florence Mining Company
Coal Processing Plant, Seward, Pennsylvania, EMB Report 72-CCL-4, U.S. Environmental
Protection Agency, Research Triangle Park, NC, February 1972.
19. Coal Preparation Plant Emission Tests: Eastern Associates Coal Company, Keystone, West
Virginia, EMB Report 72-CCL-13, U.S. Environmental Protection Agency, Research
Triangle Park, NC, February 1972.
20. Coal Preparation Plant Emission Tests: Island Creek Coal Company, Vansant, Virginia,
EMB Report 73-CCL-2, U. S. Environmental Protection Agency, Research Triangle Park,
NC, September 1972.
21. Report On Compliance Testing, Performed For Peabody Coal Company, Ha\vthome Mine,
Carlisle, Indiana, Clean Air Engineering, Palatine, IL, May 6, 1993.
11/95 Coal Cleaning 11.10-7
-------
11.11 Coal Conversion
In addition to its direct use for combustion, coal can be converted to organic gases and
liquids, thus allowing the continued use of conventional oil- and gas-fired processes when oil and gas
supplies are not available. Currently, there is little commercial coal conversion in the United States.
Consequently, it is very difficult to determine which of the many conversion processes will be
commercialized in the future. The following sections provide general process descriptions and
general emission discussions for high-, medium- and low-Btu gasification (gasifaction) processes and
for catalytic and solvent extraction liquefaction processes.
11.11.1 Process Description1"2
11.11.1.1 Gasification-
One means of converting coal to an alternate form of energy is gasification. In this process,
coal is combined with oxygen and steam to produce a combustible gas, waste gases, char, and ash.
The more than 70 coal gasification systems available or being developed in 1979 can be classified by
the heating value of the gas produced and by the type of gasification reactor used. High-Btu
gasification systems produce a gas with a heating value greater than 900 Btu/scf (33,000 J/m3).
Medium-Btu gasifiers produce a gas having a heating value between 250 - 500 Btu/scf
(9,000 - 19,000 J/m3). Low-Btu gasifiers produce a gas having a heating value of less than
250 Btu/scf (9,000 J/m3).
The majority of the gasification systems consist of 4 operations: coal pretreatment, coal
gasification, raw gas cleaning, and gas beneficiation. Each of these operations consists of several
steps. Figure 11.11-1 is a flow diagram for an example coal gasification facility.
Generally, any coal can be gasified if properly pretreated. High-moisture coals may require
drying. Some caking coals may require partial oxidation to simplify gasifier operation. Other
pretreatment operations include crushing, sizing, and briqueting of fines for feed to fixed bed
gasifiers. The coal feed is pulverized for fluid or entrained bed gasifiers.
After pretreatment, the coal enters the gasification reactor where it reacts with oxygen and
steam to produce a combustible gas. Air is used as the oxygen source for making low-Btu gas, and
pure oxygen is used for making medium- and high-Btu gas (inert nitrogen in the air dilutes the
heating value of the product). Gasification reactors are classified by type of reaction bed (fixed,
entrained, or fluidized), the operating pressure (pressurized or atmospheric), the method of ash
removal (as molten slag or dry ash), and the number of stages in the gasifier (1 or 2). Within each
class, gasifiers have similar emissions.
The raw gas from the gasifier contains varying concentrations of carbon monoxide (CO),
carbon dioxide (CO2), hydrogen, methane, other organics, hydrogen sulfide (H2S), miscellaneous acid
gases, nitrogen (if air was used as the oxygen source), particulates, and water. Four gas purification
processes may be required to prepare the gas for combustion or further beneficiation: paniculate
removal, tar and oil removal, gas quenching and cooling, and acid gas removal. The primary
function of the particulate removal process is the removal of coal dust, ash, and tar aerosols in the
raw product gas. During tar and oil removal and gas quenching and cooling, tars and oils are
condensed, and other impurities such as ammonia are scrubbed from raw product gas using either
aqueous or organic scrubbing liquors. Acid gases such as H2S, COS, CS2, mercaptans, and CO2 can
2/80 (Reformatted 1/95) Mineral Products Industry 11.11-1
-------
Coal Preparation
"Drying
"Crushing
"Partial Oxidation
"Briqueting
Coal
preparation
*Coal Hopper Gas
Tar
•Tail Gas
Gasif icatior.
Raw gas
' cleaning
Sulfur
Gas
beneficiation
product gas
High-Btu
Product Gas
Figure 11.11-1. Flow diagram of typical coal gasification plant.
11.11-2
EMISSION FACTORS
(Reformatted 1/95) 2/80
-------
be removed from gas by an acid gas removal process. Acid gas removal processes generally absorb
the acid gases in a solvent, from which they are subsequently stripped, forming a nearly pure acid gas
waste stream with some hydrocarbon carryover. At this point, the raw gas is classified as either a
low-Btu or medium-Btu gas.
To produce high-Btu gas, the heating value of the medium-Btu gas is raised by shift
conversion and methanation. In the shift conversion process, H20 and a portion of the CO are
catalytically reacted to form CO2 and H2. After passing through an absorber for CO2 removal, the
remaining CO and H2 in the product gas are reacted in a methanation reactor to yield CH4 and H20.
There are also many auxiliary processes accompanying a coal gasification facility, which
provide various support functions. Among the typical auxiliary processes are oxygen plant, power
and steam plant, sulfur recovery unit, water treatment plant, and cooling towers.
11.11.1.2 Liquefaction -
Liquefaction is a conversion process designed to produce synthetic organic liquids from coal.
This conversion is achieved by reducing the level of impurities and increasing the hydrogen-to-carbon
ratio of coal to the point that it becomes fluid. There were over 20 coal liquefaction processes in
various stages of development by both industry and Federal agencies in 1979. These processes can be
grouped into 4 basic liquefaction techniques:
- Indirect liquefaction
- Pyrolysis
- Solvent extraction
- Catalytic liquefaction
Indirect liquefaction involves the gasification of coal followed by the catalytic conversion of the
product gas to a liquid. Pyrolysis liquefaction involves heating coal to very high temperatures,
thereby cracking the coal into liquid and gaseous products. Solvent extraction uses a solvent
generated within the process to dissolve the coal and to transfer externally produced hydrogen to the
coal molecules. Catalytic liquefaction resembles solvent extraction, except that hydrogen is added to
the coal with the aid of a catalyst.
Figure 11.11-2 presents the flow diagram of a typical solvent extraction or catalytic
liquefaction plant. These coal liquefaction processes consist of 4 basic operations: coal pretreatment,
dissolution and liquefaction, product separation and purification, and residue gasification.
Coal pretreatment generally consists of coal pulverizing and drying. The dissolution of coal
is best effected if the coal is dry and finely ground. The heater used to dry coal is typically coal
fired, but it may also combust low-BTU-value product streams or may use waste heat from other
sources.
The dissolution and liquefaction operations are conducted in a series of pressure vessels. In
these processes, the coal is mixed with hydrogen and recycled solvent, heated to high temperatures,
dissolved, and hydrogenated. The order in which these operations occur varies among the
liquefaction processes and, in the case of catalytic liquefaction, involves contact widi a catalyst.
Pressures in these processes range up to 2000 psig (14,000 Pa), and temperatures range up to 900°F
(480°C). During the dissolution and liquefaction process, the coal is hydrogenated to liquids and
some gases, and the oxygen and sulfur in the coal are hydrogenated to H20 and H2S.
2/80 (Reformatted 1/95) Mineral Products Industry 11.11-3
-------
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After hydrogenation, the liquefaction products are separated through a series of flash
separators, condensers, and distillation units into a gaseous stream, various product liquids, recycle
solvent, and mineral residue. The gases from the separation process are separated further by
absorption into a product gas stream and a waste acid gas stream. The recycle solvent is returned to
the dissolution/liquefaction process, and the mineral residue of char, undissolved coal, and ash is used
in a conventional gasification plant to produce hydrogen.
The residue gasification plant closely resembles a conventional high-Btu coal gasifaction plant.
The residue is gasified in the presence of oxygen and steam to produce CO, H2, H2O, other waste
gases, and particulates. After treatment for removal of the waste gases and particulates, the CO and
H2O go into a shift reactor to produce C02 and additional H2. The H2-enriched product gas from the
residue gasifier is used subsequently in the hydrogenation of the coal.
There are also many auxiliary processes accompanying a coal liquefaction facility that provide
various support functions. Among the typical auxiliary processes are oxygen plant, power and steam
plant, sulfur recovery unit, water treatment plant, cooling towers, and sour water strippers.
11.11.2 Emissions And Controls1"3
Although characterization data are available for some of the many developing coal conversion
processes, describing these data in detail would require a more extensive discussion than possible
here. So, this section will cover emissions and controls for coal conversion processes on a qualitative
level only.
11.11.2.1 Gasification -
All of the major operations associated with low-, medium- and high-Btu gasification
technology (coal pretreatment, gasification, raw gas cleaning, and gas beneficiation) can produce
potentially hazardous air emissions. Auxiliary operations, such as sulfur recovery and combustion of
fuel for electricity and steam generation, could account for a major portion of the emissions from a
gasification plant. Discharges to the air from both major and auxiliary operations are summarized
and discussed in Table 11.11-1.
Dust emissions from coal storage, handling, and crushing/sizing can be controlled with
available techniques. Controlling air emissions from coal drying, briqueting, and partial oxidation
processes is more difficult because of the volatile organics and possible trace metals liberated as the
coal is heated.
The coal gasification process itself appears to be the most serious potential source of air
emissions. The feeding of coal and the withdrawal of ash release emissions of coal or ash dust and
organic and inorganic gases that are potentially toxic and carcinogenic. Because of their reduced
production of tars and condensable organics, slagging gasifiers pose less severe emission problems at
the coal inlet and ash outlet.
Gasifiers and associated equipment also will be sources of potentially hazardous fugitive leaks.
These leaks may be more severe from pressurized gasifiers and/or gasifiers operating at high
temperatures.
Raw gas cleaning and gas beneficiation operations appear to be smaller sources of potential air
emissions. Fugitive emissions have not been characterized but are potentially large. Emissions from
the acid gas removal process depend on the kind of removal process employed at a plant. Processes
used for acid gas removal may remove both sulfur compounds and CO2 or may be operated
2/80 (Reformatted 1/95) Mineral Products Industry 11.11-5
-------
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TS emit substantially fewer tars and oils than
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11.11-6
EMISSION FACTORS
(Reformatted 1/95) 2/80
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ission Control Choices
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Mineral Products Industry
11.11-7
-------
selectively to remove only the sulfur compounds. Typically, the acid gases are stripped from the
solvent and processed in a sulfur plant. Some processes, however, directly convert the absorbed
hydrogen sulfide to elemental sulfur. Emissions from these direct conversion processes (e. g., the
Stretford process) have not been characterized but are probably minor, consisting of CO2, air,
moisture, and small amounts of NH3.
Emission controls for 2 auxiliary processes (power and steam generation and sulfur recovery)
are discussed elsewhere in this document (Sections 1.1 and 8.13, respectively). Gases stripped or
desorbed from process waste waters are potentially hazardous, since they contain many of the
components found in the product gas. These include sulfur and nitrogen species, organics, and other
species that are toxic and potentially carcinogenic. Possible controls for these gases include
incineration, byproduct recovery, or venting to the raw product gas or inlet air. Cooling towers are
usually minor emission sources, unless the cooling water is contaminated.
11.11.2.2 Liquefaction- •
The potential exists for generation of significant levels of atmospheric pollutants from every
major operation in a coal liquefaction facility. These pollutants include coal dust, combustion
products, fugitive organics, and fugitive gases. The fugitive organics and gases could include
carcinogenic polynuclear organics, and toxic gases such as metal carbonyls, hydrogen sulfides,
ammonia, sulfurous gases, and cyanides. Many studies are currently underway to characterize these
emissions and to establish effective control methods. Table 11.11-2 presents information now
available on liquefaction emissions.
Emissions from coal preparation include coal dust from the many handling operations and
combustion products from the drying operation. The most significant pollutant from these operations
is the coal dust from crushing, screening, and drying activities. Wetting down the surface of the
coal, enclosing the operations, and venting effluents to a scrubber or fabric filter are effective means
of particulate control.
A major source of emissions from the coal dissolution and liquefaction operation is the
atmospheric vent on the slurry mix tank. The slurry mix tank is used for mixing feed coal and
recycle solvent. Gases dissolved in the recycle solvent stream under pressure will flash from the
solvent as it enters the unpressurized slurry mix tank. These gases can contain hazardous volatile
organics and acid gases. Control techniques proposed for this source include scrubbing, incineration,
or venting to the combustion air supply for either a power plant or a process heater.
Emissions from process heaters fired with waste process gas or waste liquids will consist of
standard combustion products. Industrial combustion emission sources and available controls are
discussed in Section 1.1.
The major emission source in the product separation and purification operations is the sulfur
recovery plant tail gas. This can contain significant levels of acid or sulfurous gases. Emission
factors and control techniques for sulfur recovery tail gases are discussed in Section 8.13.
Emissions from the residue gasifier used to supply hydrogen to the system are very similar to
those for coal gasifiers previously discussed in this section.
Emissions from auxiliary processes include combustion products from onsite steam/electric
power plant and volatile emissions from the waste water system, cooling towers, and fugitive
emission sources. Volatile emissions from cooling towers, waste water systems, and fugitive
11.11-8 EMISSION FACTORS (Reformatted 1/95) 2/80
-------
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Mineral Products Industry
11.11-9
-------
emission sources possibly can include every chemical compound present in the plant. These sources
will be the most significant and most difficult to control in a coal liquefaction facility. Compounds
that can be present include hazardous organics, metal carbonyls, trace elements such as mercury, and
toxic gases such as CO2, H2S, HCN, NH3, COS, and CS2.
Emission controls for waste water systems involve minimizing the contamination of water
with hazardous compounds, enclosing the waste water systems, and venting the waste water systems
to a scrubbing or incinerating system. Cooling tower controls focus on good heat exchanger
maintenance, to prevent chemical leaks into the system, and on surveillance of cooling water quality.
Fugitive emissions from various valves, seals, flanges, and sampling ports are individually small but
collectively very significant. Diligent housekeeping and frequent maintenance, combined with a
monitoring program, are the best controls for fugitive sources. The selection of durable low leakage
components, such as double mechanical seals, is also effective.
References for Section 11.11
1. C. E. Burklin and W. J. Moltz, Energy Resource Development System, EPA Contract
No. 68-01-1916, Radian Corporation and The University Of Oklahoma, Austin, TX,
September 1978.
2. E. C. Cavanaugh, et al., Environmental Assessment Data Base For Low/Medium-BTU
Gasification Technology, Volume I, EPA-600/7-77-125a, U. S. Environmental Protection
Agency, Cincinnati, OH, November 1977.
3. P. W. Spaite and G. C. Page, Technology Overview: Low- And Medium-BTU Coal
Gasification Systems, EPA-600/7-78-061, U. S. Environmental Protection Agency, Cincinnati,
OH, March 1978.
11.11-10 EMISSION FACTORS (Reformatted 1/95) 2/80
-------
11.12 Concrete Batching
11.12 Process Description1"4
Concrete is composed essentially of water, cement, sand (fine aggregate), and coarse
aggregate. Coarse aggregate may consist of gravel, crushed stone, or iron blast furnace slag. Some
specialty aggregate products could be either heavyweight aggregate (of barite, magnetite, limonite,
ilmenite, iron, or steel) or lightweight aggregate (with sintered clay, shale, slate, diatomaceous shale,
perlite, vermiculite, slag, pumice, cinders, or sintered fly ash). Concrete batching plants store,
convey, measure, and discharge these constituents into trucks for transport to a job site. In some
cases, concrete is prepared at a building construction site or for the manufacture of concrete products
such as pipes and prefabricated construction parts. Figure 11.12-1 is a generalized process diagram
for concrete batching.
The raw materials can be delivered to a plant by rail, truck, or barge. The cement is
transferred to elevated storage silos pneumatically or by bucket elevator. The sand and coarse
aggregate are transferred to elevated bins by front end loader, clam shell crane, belt conveyor, or
bucket elevator. From these elevated bins, the constituents are fed by gravity or screw conveyor to
weigh hoppers, which combine the proper amounts of each material.
Truck mixed (transit mixed) concrete involves approximately 75 percent of U. S. concrete
batching plants. At these plants, sand, aggregate, cement, and water are all gravity fed from the
weigh hopper into the mixer trucks. The concrete is mixed on the way to the site where the concrete
is to be poured. Central mix facilities (including shrink mixed) constitute the other one-fourth of the
industry. With these, concrete is mixed and then transferred to either an open bed dump truck or an
agitator truck for transport to the job site. Shrink mixed concrete is concrete that is partially mixed at
the central mix plant and then completely mixed in a truck mixer on the way to the job site. Dry
batching, with concrete mixed and hauled to the construction site in dry form, is seldom, if ever,
used.
11.12-2 Emissions And Controls5"7
Emission factors for concrete batching are given in Tables 11.12-1 and 11.12-2, with potential
air pollutant emission points shown. Paniculate matter, consisting primarily of cement dust but
including some aggregate and sand dust emissions, is the only pollutant of concern. All but one of
the emission points are fugitive in nature. The only point source is the transfer of cement to the silo,
and this is usually vented to a fabric filter or "sock". Fugitive sources include the transfer of sand
and aggregate, truck loading, mixer loading, vehicle traffic, and wind erosion from sand and
aggregate storage piles. The amount of fugitive emissions generated during the transfer of sand and
aggregate depends primarily on the surface moisture content of these materials. The extent of fugitive
emission control varies widely from plant to plant.
Types of controls used may include water sprays, enclosures, hoods, curtains, shrouds,
movable and telescoping chutes, and the like. A major source of potential emissions, the movement
of heavy trucks over unpaved or dusty surfaces in and around the plant, can be controlled by good
maintenance and wetting of the road surface.
10/86 (Reformatted 1/95) Mineral Products Industry 11.12-1
-------
8
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11.12-2
EMISSION FACTORS
(Reformatted 1/95) 10/86
-------
Table 11.12-1 (Metric Units). EMISSION FACTORS FOR CONCRETE BATCHING3
Source (SCC)
Sand and aggregate transfer to elevated bin
(3-05-01 l-06)d
Cement unloading to elevated storage silo
Pneumatic0
Bucket elevator (3-05-0 ll-07)f
Weigh hopper loading (3-05-011-8)8
Mixer loading (central mix) (3-05-0 11-09)8
Truck loading (truck mix) (3-05-011-10)8
Vehicle traffic (unpaved roads) (3-05-01 l-_)h
Wind erosion from sand and aggregate storage piles
(3-05-01 !__)'
Total process emissions (truck mix)(3-05-011-_))
PM
0.014
0.13
0.12
0.01
0.02
0.01
4.5
3.9
0.05
Filterable15
RATING
E
D
E
E
E
E
C
D
E
PM-10
ND
ND
ND
ND
ND
ND
ND
ND
ND
Condensable PMC
Inorganic
ND
ND
ND
ND
ND
ND
ND
ND
ND
Organic
ND
ND
ND
ND
ND
ND
ND
ND
ND
a Factors represent uncontrolled emissions unless otherwise noted. All emission factors are in kg/Mg
of material mixed unless noted. Based on a typical yd3 weighing 1.818 kg (4,000 Ib) and
containing 227 kg (500 Ib) cement, 564 kg (1,240 Ib) sand, 864 kg (1,900 Ib) coarse aggregate, and
164 kg (360 Ib) water. SCC = Source Classification Code. ND = no data.
b Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent)
sampling train.
c Condensable PM is that PM collected in the impinger portion of a PM sampling train.
d Reference 6.
e For uncontrolled emissions measured before filter. Based on 2 tests on pneumatic conveying
controlled by a fabric filter.
f Reference 7. From test of mechanical unloading to hopper and subsequent transport of cement by
enclosed bucket elevator to elevated bins with fabric socks over bin vent.
g Reference 5. Engineering judgment, based on observations and emissions tests of similar controlled
sources.
h From Section 13.2-1, with k = 0.8, s = 12, S = 20, W = 20, w = 14, and p = 100; units of
kg/vehicle kilometers traveled; based on facility producing 23,100 m3/yr (30,000 yd3/yr) of
concrete, with average truck load of 6.2 m3 (8 yd3) and plant road length of 161 meters (0.1 mile).
1 From Section 11.19-1, for emissions <30 micrometers from inactive storage piles; units of
kg/hectare/day.
J Based on pneumatic conveying of cement at a truck mix facility. Does not include vehicle traffic or
wind erosion from storage piles.
10/86 (Reformatted 1/95)
Mineral Products Industry
11.12-3
-------
Table 11.12-2 (English Units). EMISSION FACTORS FOR CONCRETE BATCHINGa'b
Source (SCC)
Sand and aggregate transfer to elevated bin
(3-05-011-06)e
Cement unloading to elevated storage silo
Pneumaticf
Bucket elevator (3-05-011-07)8
Weigh hopper loading (3-05-01 l-08)h
Mixer loading (central mix) (3-05-01 l-09)h
Truck loading (truck mix) (3-05-011-10)h
Vehicle traffic (unpaved roads) (3-05-011- )'
Wind erosion from sand and aggregate storage
piles (3-05-01 l-_Jf
Total process emissions (truck mix)
t3 -05-01 l-_)m
Filterable0
PM
0.029
(0.05)
0.27
(0.07)
0.24
(0.06)
0.02
(0.04)
0.04
(0.07)
0.02
(0.04)
16
(0.02)
3.5k
(O.I)1
0.1
(0.2)
RATING
E
D
E
E
E
E
C
D
E
PM-10
ND
ND
ND
ND
ND
ND
ND
ND
ND
Condensable PMd
Inorganic
ND
ND
ND
ND
ND
ND
ND
ND
ND
Organic
ND
ND
ND
ND
ND
ND
ND
ND
ND
a Factors represent uncontrolled emissions unless otherwise noted. All emission factors are in Ib/ton
(lb/yd3) of material mixed unless noted. SCC = Source Classification Code. ND = no data.
b Based on a typical yd3 weighing 1.818 kg (4,000 Ib) and containing 227 kg (500 Ib) cement, 564 kg
(1,240 Ib) sand, 864 kg (1,900 Ib) coarse aggregate, and 164 kg (360 Ib) water.
c Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent)
sampling train.
d Condensable PM is that PM collected in the impinger portion of a PM sampling train.
e Reference 6.
f For uncontrolled emissions measured before filter. Based on 2 tests on pneumatic conveying
controlled by a fabric filter.
g Reference 7. From test of mechanical unloading to hopper and subsequent transport of cement by
enclosed bucket elevator to elevated bins with fabric socks over bin vent.
h Reference 5. Engineering judgment, based on observations and emission tests of similar controlled
sources.
' From Section 13.2.1, with k = 0.8, s = 12, S = 20, W = 20, w = 14, and p = 100; units of
Ib/vehicle miles traveled; based on facility producing 23,100 m3/yr (30,000 yd3/yr) of concrete,
with average truck load of 6.2 m3 (8 yd3) and plant road length of 161 meters (0.1 mile).
J From Section 11.19.1, for emissions <30 micrometers from inactive storage piles.
k Units of Ib/acre/day.
1 Assumes 1,011 m2 (1/4 acre) of sand and aggregate storage at plant with production of
23,000 m3/yr (30,000 yd3/yr).
mBased on pneumatic conveying of cement at a truck mix facility; does not include vehicle traffic or
wind erosion from storage piles.
Predictive equations that allow for emission factor adjustment based on plant-specific
conditions are given in Chapter 13. Whenever plant specific data are available, they should be used
in lieu of the fugitive emission factors presented in Table 11.12-1.
11.12-4
EMISSION FACTORS
(Reformatted 1/95) 10/86
-------
References For Section 11.12
1. Air Pollutant Emission Factors, APTD-0923, U. S. Environmental Protection Agency,
Research Triangle Park, NC, April 1970.
2. Air Pollution Engineering Manual, 2nd Edition, AP-40, U. S. Environmental Protection
Agency, Research Triangle Park, NC, 1974. Out of Print.
3. Telephone and written communication between Edwin A. Pfetzing, PEDCo Environmental,
Inc., Cincinnati, OH, and Richard Morris and Richard Meininger, National Ready Mix
Concrete Association, Silver Spring, MD, May 1984.
4. Development Document For Effluent Limitations Guidelines And Standards Of Performance,
The Concrete Products Industries, Draft, U. S. Environmental Protection Agency,
Washington, DC, August 1975.
5. Technical Guidance For Control Of Industrial Process Fugitive Paniculate Emissions,
EPA^50/3-77-010, U. S. Environmental Protection Agency, Research Triangle Park, NC,
March 1977.
6. Fugitive Dust Assessment At Rock And Sand Facilities In The South Coast Air Basin, Southern
California Rock Products Association and Southern California Ready Mix Concrete
Association, Santa Monica, CA, November 1979.
7. Telephone communication between T. R. Blackwood, Monsanto Research Corp., Dayton,
OH, and John Zoller, PEDCo Environmental, Inc., Cincinnati, OH, October 18, 1976.
10/86 (Reformatted 1/95) Mineral Products Industry 11.12-5
-------
11.13 Glass Fiber Manufacturing
11.13.1 General1-4
Glass fiber manufacturing is the high-temperature conversion of various raw materials
(predominantly borosilicates) into a homogeneous melt, followed by the fabrication of this melt into
glass fibers. The 2 basic types of glass fiber products, textile and wool, are manufactured by similar
processes. A typical diagram of these processes is shown in Figure 11.13-1. Glass fiber production
can be segmented into 3 phases: raw materials handling, glass melting and refining, and wool glass
fiber forming and finishing, this last phase being slightly different for textile and wool glass fiber
production.
Raw Materials Handling -
The primary component of glass fiber is sand, but it also includes varying quantities of
feldspar, sodium sulfate, anhydrous borax, boric acid, and many other materials. The bulk supplies
are received by rail car and truck, and the lesser-volume supplies are received in drums and packages.
These raw materials are unloaded by a variety of methods, including drag shovels, vacuum systems,
and vibrator/gravity systems. Conveying to and from storage piles and silos is accomplished by belts,
screws, and bucket elevators. From storage, the materials are weighed according to the desired
product recipe and then blended well before their introduction into the melting unit. The weighing,
mixing, and charging operations may be conducted in either batch or continuous mode.
Glass Melting And Refining -
In the glass melting furnace, the raw materials are heated to temperatures ranging from
1500 to 1700°C (2700 to 3100°F) and are transformed through a sequence of chemical reactions to
molten glass. Although there are many furnace designs, furnaces are generally large, shallow, and
well-insulated vessels that are heated from above. In operation, raw materials are introduced
continuously on top of a bed of molten glass, where they slowly mix and dissolve. Mixing is effected
by natural convection, gases rising from chemical reactions, and, in some operations, by air injection
into the bottom of the bed.
Glass melting furnaces can be categorized by their fuel source and method of heat application
into 4 types: recuperative, regenerative, unit, and electric melter. The recuperative, regenerative,
and unit melter furnaces can be fueled by either gas or oil. The current trend is from gas-fired to oil-
fired. Recuperative furnaces use a steel heat exchanger, recovering heat from the exhaust gases by
exchange with the combustion air. Regenerative furnaces use a lattice of brickwork to recover waste
heat from exhaust gases. In the initial mode of operation, hot exhaust gases are routed through a
chamber containing a.brickwork lattice, while combustion air is heated by passage through another
corresponding brickwork lattice. About every 20 minutes, the airflow is reversed, so that the
combustion air is always being passed through hot brickwork previously heated by exhaust gases.
Electric furnaces melt glass by passing an electric current through the melt. Electric furnaces are
either hot-top or cold-top. The former use gas for auxiliary heating, and the latter use only the
electric current. Electric furnaces are currently used only for wool glass fiber production because of
the electrical properties of the glass formulation. Unit melters are used only for the "indirect" marble
melting process, getting raw materials from a continuous screw at the back of the furnace adjacent to
the exhaust air discharge. There are no provisions for heat recovery with unit melters.
9/85 (Reformatted 1/95) Mineral Products Industry 11.13-1
-------
Raw materials
receiving and handling
I
Raw materials storage
Crushing, weighing, mixing
Melting and refining
Direct
process
Wool glass fiber
Forming
Binder addition
Compression
Oven curing
Cooling
Fabrication
Packaging
Indirect
process
Marble forming
Annealing
Marble storage, shipment
Marble melting
Textile glass fiber
Forming
Sizing, binding addition
Winding
Oven drying
Oven curing
Fabrication
Packaging
Raw
material
handling
Glass
melting
and
forming
Fiber
forming
and
finishing
Figure 11.13-1. Typical flow diagram of the glass fiber production process.
11.13-2
EMISSION FACTORS
(Reformatted 1/95) 9/85
-------
In the "indirect" melting process, molten glass passes to a forehearth, where it is drawn off,
sheared into globs, and formed into marbles by roll-forming. The marbles are then stress-relieved in
annealing ovens, cooled, and conveyed to storage or to other plants for later use. In the "direct"
glass fiber process, molten glass passes from the furnace into a refining unit, where bubbles and
particles are removed by settling, and the melt is allowed to cool to the proper viscosity for the fiber
forming operation.
Wool Glass Fiber Forming And Finishing -
Wool fiberglass is produced for insulation and is formed into mats that are cut into batts.
(Loose wool is primarily a waste product formed from mat trimming, although some is a primary
product, and is only a small part of the total wool fiberglass produced. No specific emission data for
loose wool production are available.) The insulation is used primarily in the construction industry
and is produced to comply with ASTM C167-64, the "Standard Test Method for Thickness and
Density of Blanket- or Batt-Type Thermal Insulating Material".
Wool fiberglass insulation production lines usually consist of the following processes:
(1) preparation of molten glass, (2) formation of fibers into a wool fiberglass mat, (3) curing the
binder-coated fiberglass mat, (4) cooling the mat, and (5) backing, cutting, and packaging the
insulation. Fiberglass plants contain various sizes, types, and numbers of production lines, although a
typical plant has 3 lines. Backing (gluing a flat flexible material, usually paper, to the mat), cutting,
and packaging operations are not significant sources of emissions to the atmosphere.
The trimmed edge waste from the mat and the fibrous dust generated during the cutting and
packaging operations are collected by a cyclone and either are transported to a hammer mill to be
chopped into blown wool (loose insulation) and bulk packaged or are recycled to the forming section
and blended with newly formed product.
During the formation of fibers into a wool fiberglass mat (the process known as "forming" in
the industry), glass fibers are made from molten glass, and a chemical binder is simultaneously
sprayed on the fibers as they are created. The binder is a thermosetting resin that holds the glass
fibers together. Although the binder composition varies with product type, typically the binder
consists of a solution of phenol-formaldehyde resin, water, urea, lignin, silane, and ammonia.
Coloring agents may also be added to the binder. Two methods of creating fibers are used by the
industry. In the rotary spin process, depicted in Figure 11.13-2, centrifugal force causes molten glass
to flow through small holes in the wall of a rapidly rotating cylinder to create fibers that are broken
into pieces by an air stream. This is the newer of the 2 processes and dominates the industry today.
In the flame attenuation process, molten glass flows by gravity from a furnace through numerous
small orifices to create threads that are then attenuated (stretched to the point of breaking) by high
velocity, hot air, and/or a flame. After the glass fibers are created (by either process) and sprayed
with the binder solution, they are collected by gravity on a conveyor belt in the form of a mat.
The conveyor carries the newly formed mat through a large oven to cure the thermosetting
binder and then through a cooling section where ambient air is drawn down through the mat.
Figure 11.13-3 presents a schematic drawing of the curing and cooling sections. The cooled mat
remains on the conveyor for trimming of the uneven edges. Then, if product specifications require it,
a backing is applied with an adhesive to form a vapor barrier. The mat is then cut into batts of the
desired dimensions and packaged.
Textile Glass Fiber Forming And Finishing -
Molten glass from either the direct melting furnace or the indirect marble melting furnace is
temperature-regulated to a precise viscosity and delivered to forming stations. At the forming
9/85 (Reformatted 1/95) Mineral Products Industry 11.13-3
-------
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11.13-4
EMISSION FACTORS
(Reformatted 1/95) 9/85
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Mineral Products Industry
11.13-5
-------
stations, the molten glass is forced through heated platinum bushings containing numerous very small
openings. The continuous fibers emerging from the openings are drawn over a roller applicator,
which applies a coating of a water-soluble sizing and/or coupling agent. The coated fibers are
gathered and wound into a spindle. The spindles of glass fibers are next conveyed to a drying oven,
where moisture is removed from the sizing and coupling agents. The spindles are then sent to an
oven to cure the coatings. The final fabrication includes twisting, chopping, weaving, and packaging
the fiber.
11.13.2 Emissions And Controls1'3'4
Emissions and controls for glass fiber manufacturing can be categorized by the 3 production
phases with which they are associated. Emission factors for the glass fiber manufacturing industry
are given in Tables 11.13-1, 11.13-2, and 11.13-3.
Raw Materials Handling -
The major emissions from the raw materials handling phase are fugitive dust and raw material
particles generated at each of the material transfer points. Such a point would be where sand pours
from a conveyor belt into a storage silo. The 2 major control techniques are wet or moist handling
and fabric filters. When fabric filters are used, the transfer points are enclosed, and air from the
transfer area is continuously circulated through the fabric filters.
Glass Melting And Refining -
The emissions from glass melting and refining include volatile organic compounds from the
melt, raw material particles entrained in the furnace flue gas, and, if furnaces are heated with fossil
fuels, combustion products. The variation in emission rates among furnaces is attributable to varying
operating temperatures, raw material compositions, fuels, and flue gas flow rates. Of the various
types of furnaces used, electric furnaces generally have the lowest emission rates, because of the lack
of combustion products and of the lower temperature of the melt surface caused by bottom heating.
Emission control for furnaces is primarily fabric filtration. Fabric filters are effective on paniculate
matter (PM) and sulfur oxides (SOX) and, to a lesser extent, on carbon monoxide (CO), nitrogen
oxides (NOX), and fluorides. The efficiency of these compounds is attributable to both condensation
on filterable PM and chemical reaction with PM trapped on the filters. Reported fabric filter
efficiencies on regenerative and recuperative wool furnaces are for PM, 95+ percent; SOX,
99+ percent; CO, 30 percent; and fluoride, 91 to 99 percent. Efficiencies on other furnaces are
lower because of lower emission loading and pollutant characteristics.
Wool Fiber Forming And Finishing -
Emissions generated during the manufacture of wool fiberglass insulation include solid
particles of glass and binder resin, droplets of binder, and components of the binder that have
vaporized. Glass particles may be entrained in the exhaust gas stream during forming, curing, or
cooling operations. Test data show that approximately 99 percent of the total emissions from the
production line are emitted from the forming and curing sections. Even though cooling emissions are
negligible at some plants, cooling emissions at others may include fugitives from the curing section.
This commingling of emissions occurs because fugitive emissions from the open terminal end of the
curing oven may be induced into the cooling exhaust ductwork and be discharged into the
atmosphere. Solid particles of resin may be entrained in the gas stream in either the curing or cooling
sections. Droplets of organic binder may be entrained in the gas stream in the forming section or
may be a result of condensation of gaseous pollutants as the gas stream is cooled. Some of the liquid
binder used in the forming section is vaporized by the elevated temperatures in the forming and
curing processes. Much of the vaporized material will condense when the gas stream cools in the
ductwork or in the emission control device.
11.13-6 EMISSION FACTORS (Reformatted 1/95) 9/85
-------
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EMISSION FACTORS
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EMISSION FACTORS
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o
11.13-14
EMISSION FACTORS
(Reformatted 1/95) 9/85
-------
Particulate matter is the principal pollutant that has been identified and measured at wool
fiberglass insulation manufacturing facilities. It was known that some fraction of the PM emissions
results from condensation of organic compounds used in the binder. Therefore, in evaluating
emissions and control device performance for this source, a sampling method, EPA Reference
Method 5E, was used that permitted collection and measurement of both solid particles and condensed
PM.
Tests were performed during the production of R-ll building insulation, R-19 building
insulation, ductboard, and heavy-density insulation. These products, which account for 91 percent of
industry production, had densities ranging from 9.1 to 12.3 kilograms per cubic meter (kg/m3)
(0.57 to 0.77 pounds per cubic foot [Ib/ft3]) for R-ll, 8.2 to 9.3 kg/m* (0.51 to 0.58 Ib/ft3) for
R-19, and 54.5 to 65.7 kg/m3 (3.4 to 4.1 Ib/ft3) for ductboard. The heavy-density insulation had a
density of 118.5 kg/m3 (7.4 Ib/ft3). (The remaining 9 percent of industry wool fiberglass production
is a variety of specialty products for which qualitative and quantitative information is not available.)
The loss on ignition (LOI) of the product is a measure of the amount of binder present. The LOI
values ranged from 3.9 to 6.5 percent, 4.5 to 4.6 percent, and 14.7 to 17.3 percent for R-ll, R-19,
and ductboard, respectively. The LOI for heavy-density insulation is 10.6 percent. A production line
may be used to manufacture more than one of these product types because the processes involved do
not differ. Although the data base did not show sufficient differences in mass emission levels to
establish separate emission standards for each product, the uncontrolled emission factors are
sufficiently different to warrant their segregation for AP-42.
The level of emissions control found in the wool fiberglass insulation manufacturing industry
ranges from uncontrolled to control of forming, curing, and cooling emissions from a line. The
exhausts from these process operations may be controlled separately or in combination. Control
technologies currently used by the industry include wet ESPs, low- and high-pressure-drop wet
scrubbers, low- and high-temperature thermal incinerators, high-velocity air filters, and process
modifications. These added control technologies are available to all firms in the industry, but the
process modifications used in this industry are considered confidential. Wet ESPs are considered to
be best demonstrated technology for the control of emissions from wool fiberglass insulation
manufacturing lines. Therefore, it is expected that most new facilities will be controlled in this
manner.
Textile Fiber Forming And Finishing -
Emissions from the forming and finishing processes include glass fiber particles, resin
particles, hydrocarbons (primarily phenols and aldehydes), and combustion products from dryers and
ovens. Emissions are usually lower in the textile fiber glass process man in the wool fiberglass
process because of lower turbulence in the forming step, roller application of coatings, and use of
much less coating per ton of fiber produced.
References For Section 11.13
1. J. R. Schorr et al., Source Assessment: Pressed And Blown Glass Manufacturing Plants,
EPA-600/2-77-Q05, U. S. Environmental Protection Agency, Cincinnati, OH, January 1977.
2. Annual Book OfASTM Standards, Part 18, ASTM Standard C167-64 (Reapproved 1979),
American Society For Testing And Materials, Philadelphia, PA.
3. Standard Of Performance For Wool Fiberglass Insulation Manufacturing Plants, 50 FR 7700,
February 25, 1985.
9/85 (Reformatted 1/95) Mineral Products Industry 11.13-15
-------
4. Wool Fiberglass Insulation Manufacturing Industry: Background Information For Proposed
Standards, EPA-450/3-83-022a, U. S. Environmental Protection Agency, Research Triangle
Park, NC, December 1983.
5. Screening Study to Determine Need for Standards of Performance for New Sources in the
Fiber Glass Manufacturing Industry—Draft, U.S. Environmental Protection Agency,
Research Triangle Park, NC, December 1976.
11.13-16 EMISSION FACTORS (Reformatted 1/95) 9/85
-------
11.14 Frit Manufacturing
11.14.1 Process Description1"6
Frit is a homogeneous melted mixture of inorganic materials that is used in enameling iron and steel
and in glazing porcelain and pottery. Frit renders soluble and hazardous compounds inert by combining them
with silica and other oxides. Frit also is used in bonding grinding wheels, to lower vitrification temperatures,
and as a lubricant in steel casting and metal extrusion. The six digit Source Classification Code (SCC) for
frit manufacturing is 3-05-013.
Frit is prepared by fusing a variety of minerals in a furnace and then rapidly quenching the molten
material. The constituents of the feed material depend on whether the frit is to be used as a ground coat or as
a cover coat. For cover coats, the primary constituents of the raw material charge include silica, fluorspar,
soda ash, borax, feldspar, zircon, aluminum oxide, lithium carbonate, magnesium carbonate, and titanium
oxide. The constituents of the charge for a ground coat include the same compounds plus smaller amounts of
metal oxides such as cobalt oxide, nickel oxide, copper oxide, and manganese oxide.
To begin the process, raw materials are shipped to the manufacturing facility by truck or rail and are
stored in bins. Next, the raw materials are carefully weighed in the correct proportions. The raw batch then
is dry mixed and transferred to a hopper prior to being fed into the smelting furnace. Although pot furnaces,
hearth furnaces, and rotary furnaces have been used to produce frit in batch operations, most frit is now
produced in continuous smelting furnaces. Depending on the application, frit smelting furnaces operate at
temperatures of 930° to 1480°C (1700° to 2700°F). If a continuous furnace is used, the mixed charge is fed
by screw conveyor directly into the furnace. Continuous furnaces operate at temperatures of 1090c to
1430°C (2000° to 2600°F). When smelting is complete, the molten material is passed between water-cooled
metal rollers that limit the thickness of the material, and then it is quenched with a water spray that shatters
the material into small glass particles called frit.
After quenching, the frit is milled by either wet or dry grinding. If the latter, the frit is dried before
grinding. Frit produced in continuous furnaces generally can be ground without drying, and it is sometimes
packaged for shipping without further processing. Wet milling of frit is no longer common. However, if the
frit is wet-milled, it can be charged directly to the grinding mill without drying. Rotary dryers are the devices
most commonly used for drying frit. Drying tables and stationary dryers also have been used. After drying,
magnetic separation may be used to remove iron-bearing material. The frit is finely ground in a ball mill, into
which clays and other electrolytes may be added, and then the product is screened and stored. The frit
product then is transported to on-site ceramic manufacturing processes or is prepared for shipping. In recent
years, the electrostatic deposition spray method has become the preferred method of applying frit glaze to
surfaces. Frit that is to be applied in that manner is mixed during the grinding step with an organic silicon
encapsulating agent, rather than with clay and electrolytes. Figure 11.14-1 presents a process flow diagram
for frit manufacturing.
11.14.2 Emissions And Controls1-7-10
Significant emissions of particulate matter (PM) and PM less than 10 micrometers (PM-10) are
created by the frit smelting operation in the form of dust and fumes. These emissions consist primarily of
condensed metallic oxide fumes that have volatilized from the molten charge. The emissions also contain
mineral dust and sometimes hydrogen fluoride. Emissions from furnaces also include products of
combustion, such as carbon monoxide (CO), carbon dioxide (CO^, and nitrogen oxides (NOJ. Sulfur oxides
(SOX) also may be emitted, but they generally are absorbed by the molten material to form an
6/97 Mi neral Products Industry 11.14-1
-------
CLAYS. OTHER
ELECTROLYTES
RAW MATERIALS
STORAGE
WEIGHING
(3-05-013-02)
MIXING
(34541343)
FURNACE
CHARGING
(34541344)
SMELTING
FURNACE
(34541344)
QUENCHING
(346413-10)
PACKAGING
TO CERAMIC
MANUFACTURING
PROCESS
(l)
A
vl/
A
* *
DRYING
(345413-11)
j) PM EMISSIONS
(2) GASEOUS EMISSIONS
~ ELECTROLYTES OR
ENCAPSULATING AGENT
Figure 11.14-1 Process flow diagram for frit manufacturing.
(Source Classification Code in parentheses)
11.14-2
EMISSION FACTORS
6/97
-------
immiscible sulphate that is eliminated in the quenching operation. Paniculate matter also is emitted from
drying, grinding, and materials handling and transfer operations
Emissions from the furnace can be minimized by careful control of the rate and duration of raw
material heating, to prevent volatilization of the more fusible charge materials. Emissions from rotary
furnaces also can be reduced with careful control of the rotation speed, to prevent excessive dust carryover.
Venturi scrubbers and fabric filters are the devices most commonly used to control emissions from frit
smelting furnaces, and fabric filters are commonly used to control emissions from grinding operations. No
information is available on the type of emission controls used on quenching, drying, and materials handling
and transfer operations.
Table 11.14-1 presents emission factors for filterable PM, CO, NOW and CO^ emissions from frit
manufacturing. Table 11.14-2 presents emission factors for other pollutant emissions from frit
manufacturing.
11.14.3 Updates Since the Fifth Edition
The Fifth Edition was released in January 1995. A complete revision of this section was completed
on 11/95. The emission factor for NOx for Smelting Furnace was revised on 6/97 based upon a review of the
production information that was provided by the manufacturing facility.
Table 11.14-1. EMISSION FACTORS FOR FRIT MANUFACTURING2
EMISSION FACTOR RATING: E
Source
Smelting furnace
(SCC 3-05-0 13-05,06)
Smelting furnace with venturi scrubber
(SCC 3-05-013-05,06)
Smelting furnace with fabric filter
(SCC 3-05-0 13-05.-06)
Filterable PMb
16C
1.8f
0.020d
CO
4.8C
g
g
NOX
16d
g
g
C02
1,300°
g
g
* Factors represent uncontrolled emissions unless otherwise noted. Emission factor units are Ib/ton of
feed material. ND = no data. SCC = Source Classification Code. To convert from Ib/ton to kg/Mg,
multiply by 0.5.
b Filterable PM is that PM collected on or prior to the filter of an EPA Method 5 (or equivalent)
sampling train.
c Reference 1.
d Reference 10.
'Reference 7-10.
f References 7-9. EMISSION FACTOR RATING: D
8 See factor for uncontrolled emissions.
6/97
Mineral Products Industry
11.14-3
-------
Table 11.14-2. EMISSION FACTORS FOR FRIT MANUFACTURING--
FLUORIDES AND METALS8
EMISSION FACTOR RATING: E
Smelting furnace with fabric filter
(SCC 3-05-0 13-05,-06)
Pollutant
fluorides
barium
chromium
cobalt
copper
lead
manganese
nickel
zinc
Emission factor, Ib/ton
0.88
2.8 x lO'5
1.4 xlO'5
4.3 x ID'6
1.9 x ID'5
9.6 x Ifr6
1.4 x 10-5
1.6 x Ifr5
1.2 xlO-4
'Reference 10. Factor units are Ib/ton of material feed.
SCC = Source Classification Code. To convert from Ib/ton to kg/Mg, multiply by 0.5.
References For Section 11.14
1. J. L. Spinks, "Frit Smelters", Air Pollution Engineering Manual, Danielson, J. A. (ed.), PHS Publication
Number 999-AP-40, U. S. Department Of Health, Education, And Welfare, Cincinnati, OH, 1967.
2. "Materials Handbook", Ceramic Industry, Troy, MI, January 1994.
3. Andrew I. Andrews, Enamels: The Preparation, Application, And Properties Of Vitreous Enamels,
Twin City Printing Company, Champaign, IL, 1935.
4. Written communication from David Ousley, Alabama Department of Environmental Management,
Montgomery, AL, to Richard Marinshaw, Midwest Research Institute, Gary, NC, April 1,1993.
5. Written communication from Bruce Larson, Chi-Vit Corporation, Urbana, OH, to David Ousley,
Alabama Department Of Environment Management, Montgomery, AL, October 10,1994.
6. Written communication from John Jozefowski, Miles Industrial Chemicals Division, Baltimore, MD, to
Ronald E. Myers, U. S. Environmental Protection Agency, Research Triangle Park, NC, September 22,
1994.
11.14-4
EMISSION FACTORS
6/97
-------
7. Particulate Emissions Test Results, No. 2 North Stack, Chi-Vit Corporation, Leesburg, Alabama,
ATC, Inc. Auburn, AL, May 1987.
8. No. I South Stack P articulate Test Report, Chi-Vit Corporation, Leesburg, Alabama, April 1989,
ATC, Inc., Auburn, AL, May 1989.
9. Frit Unit No. 2, Scrubber No. 2, P articulate Emission Test Report, Chi-Vit Corporation, Leesburg,
Alabama, April 1991, ATC, Inc., Auburn, AL, April 1991.
10. Diagnostic Test, Dry Gas Cleaning Exhauster Stack, Miles, Inc., International Technology Corporation,
Monroeville, PA, February 1994.
6/97 Mineral Products Industry 11.14-5
-------
11.15 Glass Manufacturing
11.15.1 General1'5
Commercially produced glass can be classified as soda-lime, lead, fused silica, borosilicate, or
96 percent silica. Soda-lime glass, since it constitutes 77 percent of total glass production, is
discussed here. Soda-lime glass consists of sand, limestone, soda ash, and cullet (broken glass). The
manufacture of such glass is in four phases: (1) preparation of raw material, (2) melting in a furnace,
(3) forming and (4) finishing. Figure 11.15-1 is a diagram for .typical glass manufacturing.
The products of this industry are flat glass, container glass, and pressed and blown glass.
The procedures for manufacturing glass are the same for all products except forming and finishing.
Container glass and pressed and blown glass, 51 and 25 percent respectively of total soda-lime glass
production, use pressing, blowing or pressing and blowing to form the desired product. Flat glass,
which is the remainder, is formed by float, drawing, or rolling processes.
As the sand, limestone, and soda ash raw materials are received, they are crushed and stored
in separate elevated bins. These materials are then transferred through a gravity feed system to a
weigher and mixer, where the material is mixed with cullet to ensure homogeneous melting. The
mixture is conveyed to a batch storage bin where it is held until dropped into the feeder to the melting
furnace. All equipment used in handling and preparing the raw material is housed separately from the
furnace and is usually referred to as the batch plant. Figure 11.15-2 is a flow diagram of a typical
batch plant.
The furnace most commonly used is a continuous regenerative furnace capable of producing
between 45 and 272 megagrams (Mg) (50 and 300 tons) of glass per day. A furnace may have either
side or end ports that connect brick checkers to the inside of the melter. The purpose of brick
checkers (Figure 11.15-3 and Figure 11.15-4) is to conserve fuel by collecting furnace exhaust gas
heat that, when the air flow is revefsed, is used to preheat the furnace combustion air. As material
enters the melting furnace through the feeder, it floats on the top of the molten glass already in the
furnace. As it melts, it passes to the front of the melter and eventually flows through a throat leading
to the refiner. In the refiner, the molten glass is heat conditioned for delivery to the forming process.
Figures 11.15-3 and 11.15-4 show side port and end port regenerative furnaces.
After refining, the molten glass leaves the furnace through forehearths (except in the float
process, with molten glass moving directly to the tin bath) and goes to be shaped by pressing,
blowing, pressing and blowing, drawing, rolling, or floating to produce the desired product. Pressing
and blowing are performed mechanically, using blank molds and glass cut into sections (gobs) by a
set of shears. In the drawing process, molten glass is drawn upward in a sheet through rollers, with
thickness of the sheet determined by the speed of the draw and the configuration of the draw bar.
The rolling process is similar to the drawing process except that the glass is drawn horizontally on
plain or patterned rollers and, for plate glass, requires grinding and polishing. The float process is
different, having a molten tin bath over which the glass is drawn and formed into a finely finished
surface requiring no grinding or polishing. The end product undergoes finishing (decorating or
coating) and annealing (removing unwanted stress areas in the glass) as required, and is then
inspected and prepared for shipment to market. Any damaged or undesirable glass is transferred back
to the batch plant to be used as cullet.
10/86 (Reformatted 1/95) Mineral Products Industry 11.15-1
-------
RAW
MATERIAL
MELTING
FURNACE
FINISHING
FINISHING
.GLASS
FORMING
ANNEALING
INSPECTION
AND
TESTING
GULLET
CRUSHING
RECYCLE UNDESIRABLE
GLASS
PACKING
STORAGE
OR
SHIPfING
Figure 11.15-1. Typical glass manufacturing process.
STORAGE IINS
iltlOR RA1 N4TERIAIS
MINOR
INGREDIENT
STORAGE
BINS
SCREI
CONVET3R
84TCH
STORAGE
BIN
FURNACE
FEEDER
SI ASS i
KELTIN; i
FURNACE
Figure 11.15-2. General diagram of a batch plant.
11.15-2
EMISSION FACTORS
(Reformatted 1/95) 10/86
-------
Figure 11.15-3. Side port continuous regenerative furnace.
Figure 11.15-4. End port continuous regenerative furnace.
10/86 (Reformatted 1/95)
Mineral Products Industry
11.15-3
-------
11.15.2 Emissions And Controls1"5
The main pollutant emitted by the batch plant is particulates in the form of dust. This can be
controlled with 99 to 100 percent efficiency by enclosing all possible dust sources and using
baghouses or cloth filters. Another way to control dust emissions, also with an efficiency
approaching 100 percent, is to treat the batch to reduce the amount of fine particles present, by
presintering, briquetting, pelletizing, or liquid alkali treatment.
The melting furnace contributes over 99 percent of the total emissions from a glass plant, both
particulates and gaseous pollutants. Particulates result from volatilization of materials in the melt that
combine with gases and form condensates. These either are collected in the checker work and gas
passages or are emitted to the atmosphere. Serious problems arise when the checkers are not properly
cleaned in that slag can form, clog the passages, and eventually deteriorate the condition and
efficiency of the furnace. Nitrogen oxides form when nitrogen and oxygen react in the high
temperatures of the furnace. Sulfur oxides result from the decomposition of the sulfates in the batch
and sulfur in the fuel. Proper maintenance and firing of the furnace can control emissions and also
add to the efficiency of the furnace and reduce operational costs. Low-pressure wet centrifugal
scrubbers have been used to control paniculate and sulfur oxides, but their inefficiency
(approximately 50 percent) indicates their inability to collect particulates of submicrometer size.
High-energy venturi scrubbers are approximately 95 percent effective in reducing paniculate and
sulfur oxide emissions. Their effect on nitrogen oxide emissions is unknown. Baghouses, with up to
99 percent paniculate collection efficiency, have been used on small regenerative furnaces, but fabric
corrosion requires careful temperature control. Electrostatic precipitators have an efficiency of up to
99 percent in the collection of particulates. Tables 11.15-1 and 11.15-2 list controlled and
uncontrolled emission factors for glass manufacturing. Table 11.15-3 presents particle size
distributions and corresponding emission factors for uncontrolled and controlled glass melting
furnaces, and these are depicted in Figure 11.15-5.
Emissions from the forming and finishing phases depend upon the type of glass being
manufactured. For container, press, and blow machines, the majority of emissions results from the
gob coming into contact with the machine lubricant. Emissions, in the form of a dense white cloud
that can exceed 40 percent opacity, are generated by flash vaporization of hydrocarbon greases and
oils. Grease and oil lubricants are being replaced by silicone emulsions and water soluble oils, which
may virtually eliminate this smoke. For flat glass, the only contributor to air pollutant emissions is
gas combustion in the annealing lehr (oven), which is totally enclosed except for product entry and
exit openings. Since emissions are small and operational procedures are efficient, no controls are
used on flat glass processes.
11.15-4 EMISSION FACTORS (Reformatted 1/95) 10/86
-------
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11.15-5
-------
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EMISSION FACTORS
(Reformatted 1/95) 10/86
-------
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10/86 (Reformatted 1/95)
Mineral Products Industry
11.15-7
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References 6-7. Particulate com
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11.15-8
EMISSION FACTORS
(Reformatted 1/95) 10/86
-------
p«tC«t
— Ealsslon factor
COHTVOLLD
-•— u«ifht p«rc*flc
Parclei* 4lM*c«r. »
Figure 11.15-5. Particle size distributions and emission factors for glass melting furnace exhaust.
Table 11.15-3 (Metric Units). PARTICLE SIZE DISTRIBUTIONS AND EMISSION FACTORS
FOR UNCONTROLLED AND CONTROLLED MELTING FURNACES
IN GLASS MANUFACTURINGa
EMISSION FACTOR RATING: E
Aerodynamic Particle
Diameter, /un
2.5
6.0
10
Particle Size
Uncontrolled
91
93
95
Distribution15
ESP Controlled*1
53
66
75
Size-Specific Emission
Factor, kg/Mgc
Uncontrolled
0.64
0.65
0.66
a References 8-11.
b Cumulative weight % of particles < corresponding particle size.
c Based on mass particulate emission factor of 0.7 kg/Mg glass produced, from Table 11.15-1. Size-
specific emission factor = mass particulate emission factor x particle size distribution, %/100.
After ESP control, size-specific emission factors are negligible.
d References 8-9. Based on a single test.
10/86 (Reformatted 1/95)
Mineral Products Industry
11.15-9
-------
References For Section 11.15
1. J. A. Danielson, ed., Air Pollution Engineering Manual, 2nd Ed., AP-40,
U. S. Environmental Protection Agency, Research Triangle Park, NC, May 1973. Out of
Print.
2. Richard B. Reznik, Source Assessment: Flat Glass Manufacturing Plants,
EPA-600/20-76-032b, U. S. Environmental Protection Agency, Cincinnati, OH, March 1976.
3. J. R. Schoor, et al., Source Assessment: Glass Container Manufacturing Plants,
EPA-600/2-76-269, U. S. Environmental Protection Agency, Cincinnati, OH, October 1976.
4. A. B. Tripler, Jr. and G. R. Smithson, Jr., A Review Of Air Pollution Problems And Control
In The Ceramic Industries, Battelle Memorial Institute, Columbus, OH, presented at the 72nd
Annual Meeting of the American Ceramic Society, May 1970.
5. J. R. Schorr, et al., Source Assessment: Pressed And Blown Glass Manufacturing Plants,
EPA-600/77-005, U. S. Environmental Protection Agency, Cincinnati, OH, January 1977.
6. Control Techniques For Lead Air Emissions, EPA-450/2-77-012, U. S. Environmental
Protection Agency, Research Triangle Park, NC, December 1977.
7. Confidential test data, Pedco-Environmental Specialists, Inc., Cincinnati, OH.
8. H. J. Taback, Fine Particle Emissions From Stationary And Miscellaneous Sources In The
South Coast Air Basin, PS-293-923, National Technical Information Service, Springfield, VA,
February 1979.
9. Emission test data from Environmental Assessment Data Systems, Fine Particle Emission
Information System (FPEIS), Series Report No. 219, U. S. Environmental Protection Agency,
Research Triangle Park, NC,- June 1983.
10. Environmental Assessment Data Systems, op. cit., Series No. 223.
11. Environmental Assessment Data Systems, op. cit., Series No. 225.
H.15-10 EMISSION FACTORS (Reformatted 1/95) 10/86
-------
11.16 Gypsum Manufacturing
11.16.1 Process Description1"2
Gypsum is calcium sulfate dihydrate (CaSO4 • 2H2O), a white or gray naturally occurring
mineral. Raw gypsum ore is processed into a variety of products such as a portland cement additive,
soil conditioner, industrial and building plasters, and gypsum wallboard. To produce plasters or
wallboard, gypsum must be partially dehydrated or calcined to produce calcium sulfate hemihydrate
(CaSO4 • ViH2O), commonly called stucco.
A flow diagram for a typical gypsum process producing both crude and finished gypsum
products is shown in Figure 11.16-1. In this process gypsum is crushed, dried, ground, and calcined.
Not all of the operations shown in Figure 11.16-1 are performed at all gypsum plants. Some plants
produce only wallboard, and many plants do not produce soil conditioner.
Gypsum ore, from quarries and underground mines, is crushed and stockpiled near a plant.
As needed, the stockpiled ore is further crushed and screened to about 50 millimeters (2 inches) in
diameter. If the moisture content of the mined ore is greater than about 0.5 weight percent, the ore
must be dried in a rotary dryer or a heated roller mill. Ore dried in a rotary dryer is conveyed to a
roller mill, where it is ground to the extent that 90 percent of it is less 149 micrometers (/tm)
(100 mesh). The ground gypsum exits the mill in a gas stream and is collected in a product cyclone.
Ore is sometimes dried in the roller mill by heating the gas stream, so that drying and grinding are
accomplished simultaneously and no rotary dryer is needed. The finely ground gypsum ore is known
as landplaster, which may be used as a soil conditioner.
In most plants, landplaster is fed to kettle calciners or flash calciners, where it is heated to
remove three-quarters of the chemically bound water to form stucco. Calcination occurs at
approximately 120 to 150°C (250 to 300°F), and 0.908 megagrams (Mg) (1 ton) of gypsum calcines
to about 0.77 Mg (0.85 ton) of stucco.
In kettle calciners, the gypsum is indirectly heated by hot combustion gas passed through flues
in the kettle, and the stucco product is discharged into a "hot pit" located below the kettle. Kettle
calciners may be operated in either batch or continuous mode. In flash calciners, the gypsum is
directly contacted with hot gases, and the stucco product is collected at the bottom of the calciner.
At some gypsum plants, drying, grinding, and calcining are performed in heated impact mills.
In these mills hot gas contacts gypsum as it is ground. The gas dries and calcines the ore and then
conveys the stucco to a product cyclone for collection. The use of heated impact mills eliminates the
need for rotary dryers, calciners, and roller mills.
Gypsum and stucco are usually transferred from one process to another by means of screw
conveyors or bucket elevators. Storage bins or silos are normally located downstream of roller mills
and calciners but may also be used elsewhere.
7/93 (Reformatted 1/95) Mineral Products Industry 11.16-1
-------
Crushed Rock
Storage Bios
El
©
©
Product
Cyclone
Key ID Source Classification Codes
S3
E
m
m
m
m
m
CD
E
E
3-05-015-05, -06
34)5-015-06
3-05-015-07
3-05-015-09
3-05-015-01
3-05-015-02
3-05-015-04
3-05-015-11, -12
3-05-015-14
3-05-015-18
3-05-015-17
3-05-015-21, -22
/-^
Landplaster
r T
Conveying
El
Storage ffin
©
T T
Conveying
s
©
Calciner
Sold as
Prefabricated
Board
Products
Key to Emission Sauces
(T) Point Source PM Fmi*"'""*
Combustion Emissions
(j) Fugitive PM Emissions
w
Papa Rolls
^
Chamfering j |
Hi \o
Boardhne Conveyor
y
Multi-deck
Board Drying
Kite
i
Board End
Sawing
[2
Figure 11.16-1. Overall process flow diagram for gypsum processing.2
11.16-2
EMISSION FACTORS
(Reformatted 1/95) 7/93
-------
In the manufacture of plasters, stucco is ground further in a tube or ball mill and then batch-
mixed with retarders and stabilizers to produce plasters with specific setting rates. The thoroughly
mixed plaster is fed continuously from intermediate storage bins to a bagging operation.
In the manufacture of wallboard, stucco from storage is first mixed with dry additives such as
perlite, starch, fiberglass, or vermiculite. This dry mix is combined with water, soap foam,
accelerators and shredded paper, or pulpwood in a pin mixer at the head of a board forming line.
The slurry is then spread between 2 paper sheets that serve as a mold. The edges of the paper are
scored, and sometimes chamfered, to allow precise folding of the paper to form the edges of the
board. As the wet board travels the length of a conveying line, the calcium sulfate hemihydrate
combines with the water in the slurry to form solid calcium sulfate dihydrate, or gypsum, resulting in
rigid board. The board is rough-cut to length, and it enters a multideck kiln dryer, where it is dried
by direct contact with hot combustion gases or by indirect steam heating. The dried board is
conveyed to the board end sawing area and is trimmed and bundled for shipment.
11.16.2 Emissions And Controls2'7
Potential emission sources in gypsum processing plants are shown in Figure 11.16-1. While
paniculate matter (PM) is the dominant pollutant in gypsum processing plants, several sources may
emit gaseous pollutants also. The major sources of PM emissions include rotary ore dryers, grinding
mills, calciners, and board end sawing operations. Paniculate matter emission factors for these
operations are shown in Table 11.16-1 and 11.16-2. In addition, emission factors for PM less than or
equal to 10 /un in aerodynamic diameter (PM-10) emissions from selected processes are presented in
Tables 11.16-1 and 11.16-2. All of these factors are based on output production rates. Particle size
data for ore dryers, calciners, and board end sawing operations are shown in Tables 11.16-2 and
11.16-3.
The uncontrolled emission factors presented in Table 11.16-1 and 11.16-2 represent the
process dust entering the emission control device. It is important to note that emission control
devices are frequently needed to collect the product from some gypsum processes and, thus, are
commonly thought of by the industry as process equipment and not as added control devices.
Emissions sources in gypsum plants are most often controlled with fabric filters. These
sources include:
- rotary ore dryers (SCC 3-05-015-01) - board end sawing (SCC 3-05-015-21,-22)
- roller mills (SCC 3-05-015-02) - scoring and chamfering (SCC 3-05-015-_J
- impact mills (SCC 3-05-015-13) - plaster mixing and bagging (SCC 3-05-015-16,-17)
- kettle calciners (SCC 3-05-015-11) - conveying systems (SCC 3-05-015-04)
- flash calciners (SCC 3-05-015-12) - storage bins (SCC 3-05-015-09,-10,-14)
Uncontrolled emissions from scoring and chamfering, plaster mixing and bagging, conveying systems,
and storage bins are not well quantified.
Emissions from some gypsum sources are also controlled with electrostatic precipitators
(ESP). These sources include rotary ore dryers, roller mills, kettle calciners, and conveying systems.
Although rotary ore dryers may be controlled separately, emissions from roller mills and conveying
systems are usually controlled jointly with kettle calciner emissions. Moisture in the kettle calciner
exit gas improves the ESP performance by lowering the resistivity of the dust.
7/93 (Reformatted 1/95) Mineral Products Industry 11.16-3
-------
Table 11.16-1 (Metric Units). EMISSION FACTORS FOR GYPSUM PROCESSING"
EMISSION FACTOR RATING: D
Process
Crushers, screens, stockpiles, and
roads (SCC 3-05-015-05,-06,-07,-08)
Rotary ore dryers (SCC 3-05-015-01)
Rotary ore dryers w/fabric filters
(SCC 3-05-015-01)
Roller mills w/cyclones
(SCC 3-05-015-02)
Roller mills w/fabric filters
(SCC 3-05-015-02)
Roller mill and kettle calciner
w/electrostatic precipitators
(SCC 3-05-015-02,-! 1)
Continuous kettle calciners and hot pit
(SCC 3-05-015-11)
Continuous kettle calciners and hot pit
w/fabric filters (SCC 3-05-015-11)
Continuous kettle calciners w/cyclones
and electrostatic precipitators
(SCC 3-05-015-11)
Flash calciners (SCC 3-05-015-12)
Flash calciners w/fabric filters
(SCC 3-05-015-12)
Impact mills w/cyclones
(SCC 3-05-015-13)
Impact mills w/fabric filters
(SCC 3-05-015-13)
Board end sawing~2.4-m boards
(SCC 3-05-015-21)
Board end sawing— 3. 7-m boards
(SCC 3-05-015-22)
Board end sawing w/fabric filters--
2.4-and 3. 7-m boards
(SCC 3-05-015-21, -22)
Filterable PMb
_d
0.0042(FFF)1-7e
0.0208
1.3h
0.060h
0.050hJ
21k
0.0030k
0.050*
19m
0.020m
50P
0.01QP
0.0401
0.0301
36r
PM-10
_d
0.00034(FFF)L7
0.0052
ND
ND
ND
13
ND
ND
7.2m
0.017m
ND
ND
ND
ND
27r
C02C
NA
12f
NA
NA
NA
ND
ND
NA
NA
55"
ND
NA
NA
NA
NA
NA
a Factors represent uncontrolled emissions unless otherwise specified. All emission factors are kg/Mg
of output rate. SCC = Source Classification Code. NA = not applicable. ND = no data.
b Filterable PM is that PM collected on or prior to an EPA Method 5 (or equivalent) sampling train.
11.16-4
EMISSION FACTORS
(Reformatted 1/95) 7/93
-------
Table 11.16-1 (cont.).
c Typical pollution control devices generally have a negligible effect on CO2 emissions.
d Factors for these operations are in Sections 11.19 and 13.2.
e References 3-4,8,11-12. Equation is for the emission rate upstream of any process cyclones and
applies only to concurrent rotary ore dryers with flow rates of 7.5 cubic meters per second (m3/s)
or less. FFF in the uncontrolled emission factor equation is "flow feed factor," the ratio of gas
mass rate per unit dryer cross section area to the dry mass feed rate, in the following units:
(kg/hr-m2 of gas flow)/(Mg/hr dry feed). Measured uncontrolled emission factors for 4.2 and
5.7 m3/s range from 5 to 60 kg/Mg.
f References 3-4.
g References 3-4,8,11-12. Applies to rotary dryers with and without cyclones upstream of fabric
filter.
h References 11-14. Applies to both heated and unheated roller mills.
J References 11-14. Factor is for combined emissions from roller mills and kettle calciners, based on
the sum of the roller mill and kettle calciner output rates.
k References 4-5,11,13-14. Emission factors based on the kettle and the hot pit do not apply to batch
kettle calciners.
mReferences 3,6,10.
n References 3,6,9.
p References 9,15. As used here, an impact mill is a process unit used to dry, grind, and calcine
gypsum simultaneously.
q References 4-5,16. Emission factor units = kg/m2. Based on 13-mm board thickness and 1.2 m
board width. For other thicknesses, multiply the appropriate emission factor by 0.079 times board
thickness in mm.
r References 4-5,16. Emission factor units = |