EPA-450/3-76-043
December 1976
SOURCE TEST
EVALUATION
FOR FEED AND GRAIN
INDUSTRY
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-450/3-76-043
SOURCE TEST EVALUATION
FOR FEED AND GRAIN
INDUSTRY
by
M.P. Schrag, P:G. Gorman, and W.H. Maxwell
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Contract No. 68-02-1403
Task Order No. 28
EPA Project Officer: Thomas F. Lahre
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
December 1976
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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited numbe'r of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - in limited quantities - from the
Library Services Office (MD-35) , Research Triangle Park, North Carolina
27711; or, for a fee, from the National Technical Information Service,
5285 Port Royal Road, Springfield, Virginia 22161.
This report was furnished to the Environmental Protection Agency by
Midwest Research Institute, 425 Volker Boulevard, Kansas City, Missouri
64110, in fulfillment of Contract No. 68-02-1403, Task Order No. 28.
The contents of this report are reproduced herein as received from
Midwest Research Institute. The opinions, findings, and conclusions
expressed are those of the author and not necessarily those of the Environ-
mental Protection Agency. Mention of company or product names is
not to be considered as an endorsement by the Environmental Protection
Agency.
Publication No. EPA-450/3-76-043
11
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PREFACE
This report was prepared for the Environmental Protection Agency (EPA)
under Contract No. 68-02-1403 (Task 28). The primary purpose of the work
was to evaluate emission test data for country elevators in order to revise
and update previous work done by Midwest Research Institute (MRI) for EPA
that was contained in the EPA Publication No. EPA-450/3-75-054 entitled
"Emission Factor Development for the Feed and Grain Industry." The country
elevator test data that were evaluated consisted of recent tests conducted
by MRI for EPA at two elevators in Kansas and other test reports at eleva-
tors in North Dakota that were supplied by Mr. Dana Mount of the North Dakota
State Department of Health. Mr. Mount's assistance in this and previous work
is gratefully acknowledged.
This report was written by Mr. M. P. Schrag, Head, Environmental Systems
Section, and Mr. P. G. Gorman with the assistance of Mr. W. H. Maxwell.
Approved for:
MIDWEST RESEARCH INSTITUTE
of. \-
L. J. Shannon, Director
Environmental and Materials
Sciences Division
December 28, 1976
iii
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CONTENTS
Page
List of Tables vii
Introduction 1
Feed and Grain Mills and Elevators 3
Emission Factors 3
General 3
Emissions and Controls 3
Background and Support Information for Emission Factors for
Feed and Grain Mills and Elevators 11
General 11
Emissions and Controls 11
References 21
Appendix A - Emission Factors for Grain Dryers at Grain Elevators. 23
Appendix B - Derivation of Emission Factors for Grain Processing
Operations 25
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TABLES
No. Title Page
1 Particulate Emission Factors for Grain Elevators .... 5
2 Particulate Emission Factors for Grain Elevators Based
on Amount of Grain Received or Shipped 6
3 Particulate Emission Factors for Grain Processing
Operations 8
4 Particulate Emission Factors for Grain Elevators .... 12
5 Best Average Value of Long-Terra Composite Emission
Factors for a Terminal Elevator 14
6 Summary of Uncontrolled Emission Factor Data From Tests
at Country Elevators 14
7 Particulate Emission Factors for Grain Elevators Based
on Amount of Grain Received or Shipped 15
8 Average Values Used for Ratio of Tons Processed to
Tons Shipped or Received ..... 16
9 Particulate Emission Factors for Grain Processing
Operations 18
A-l Summary of Available Emission Factor Data for Grain
Dryers 24
vii
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INTRODUCTION
This task report is a revised version of a previous document prepared
by MRI for EPA entitled "Emission Factor Development for the Feed and Grain
Industry" (EPA-450/3-75-054) dated October 1974. The subject of this report
is emission factors for grain elevators and other feed and grain operations
(excluding alfalfa dehydration)t Consistent with the previous report, this
report is arranged as follows:
Emissions and Controls
Grain Elevators
Grain Processing Operations
Background and Support Information for Emission Factors for Feed and
Grain Mills and Elevators
Grain Elevators
Grain Processing Operations
Major portions of the information and data presented in this report
are the same as that in the previous document. The primary difference is
the revision of some data for country elevators based on recent EPA tests
conducted at two elevators in Kansas, and other reports made available
through the North Dakota State Department of Health. To our knowledge, no
other new information or data have become available for reevaluation of
emission factors for the subject sources in the feed and grain industry.
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FEED AND GRAIN MILLS AND ELEVATORS
EMISSION FACTORS
General
Grain elevators are transfer and storage areas for grain and are usu-
ally classified as either country, terminal, or export elevators. Country
elevators generally receive grains as they are harvested from fields within
a 10- to 20-mile radius of the elevator. The country elevators unload, weigh
and store grain as it is received from the farmer. In addition, the country
elevator may dry or clean the grain before it is shipped to the terminal
elevators or processors. ,
Terminal elevators receive most of their grain from country elevators
and ship to processors, other terminals, and exporters. The primary func-
tion of a terminal elevator is to store grain in quantity without deterio-
ration and to bring it to commercial grade so as to conform to the needs
of buyers. As with country elevators, terminals dry, clean and sort grain.
In addition, they can blend grain to meet buyer specifications.
Export elevators are similar to terminal elevators with the exception
that they mainly load grain on ships for export.
The other types of operations involved in the processing of grain, in
grain and feed plants, range from very simple mixing steps to complex pro-
cesses which are characteristic of industrial processing plants. Included
are such diverse processes as: (a) simple mixing processes in feed mills,
(b) grain milling in flour mills, (c) solvent extracting in soybean process-
ing plants, and (d) a complex series of processing steps in a corn wet-
milling plant.
Emissions and Controls
Grain handling, milling and processing include a variety of operations
from the initial receipt of the grain at either a country or terminal eleva-
tor to the delivery of a finished product. Flour, livestock feed, soybean
oil and corn syrup are among the products produced from plants in the grain
and feed industry. Emissions from the feed and grain industry can be sepa-
rated into two general areas, those occurring at grain elevators and those
occurring at grain processing operations.
3
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Grain Elevators - Grain elevator emissions can occur from many different
operations in the elevator including unloading (receiving), loading (ship-
ping), drying, cleaning, headhouse (legs), tunnel belt, gallery belt and
belt trippers. Bnission factors for these operations at terminal, country
and export elevators are presented in Table 1.
Most of the emission factors shown in Table 1 for terminal and export
elevators are based on results reported in Ref. 1. Bnission factors for
drying were based on information in Refs. 2 and 3. For country elevators,
the emission factors were based on the results in Ref. 1 and specific emis-
sion tests at country elevators (Refs. 4 to 9). All of these emission fac-
tors are approximate average values intended to reflect a variety of grain
types. Actual emission factors for a specific source may be considerably
different, depending on the type of grain, i.e., corn, soybeans, wheat, and
other factors such as grain quality.
The emission factors shown in Table 1 represent the amount of dust
generated per ton of grain processed through each of the designated opera-
tions (i.e., uncontrolled emission factors). Amounts of grain processed
through each of these operations in a given elevator are dependent on such
factors as the amount of grain turned (interbin transfer), amount dryed,
and amount cleaned, etc. Because the amount of grain passing through each
operation is often difficult to determine, it may be more useful to express
the emission factors in terms of the amount of grain shipped or received,
assuming these amounts are about the same over the long term. Bnission fac-
tors from Table 1 have been modified accordingly and are shown in Table 2
along with the appropriate multiplier that was used as representative of
typical ratios of throughput at each operation to the amount of grain
shipped or received. This ratio is an approximate value based on average
values for turning, cleaning, and drying in each type of elevator. How-
ever, operating practices in individual elevators are different, so these
ratios, like the basic emission factors themselves, would be more valid
for a group of elevators rather than individual elevators.
The factors in Tables 1 or 2 should not be added together in an at-
tempt to obtain a single emission factor value for grain elevators because
in most elevators some of the operations are equipped with control devices
and some are not. Therefore, any estimation of emissions must be directed
to each operation and its associated control device, rather than the ele-
vator as a whole, unless the purpose was to estimate total potential (i.e.,
uncontrolled) emissions. An example of the use of emission factors in mak-
ing an emission inventory is contained in Ref. 3.
Some of the operations listed in the tables, such as the tunnel belt
and belt tripper, are internal or in-house dust sources which, if uncon-
trolled, might show lower than expected atmospheric emissions because of
internal settling of dust. The reduction in emissions via internal settling
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Table 1. PARTICULATE EMISSION FACTORS FOR
GRAIN ELEVATORS-iz2/
Type of source
Emission factor (uncontrolled)^/
(Ib/ton) (kg/MT)
Terminal of elevators
Unloaded (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Dryingk/
Cleaning-'
Headhouse (legs)
Tripper (gallery belt)
Country elevators
Unloading (receiving)
Loading (shipping)
Removal from bins
Drying—'
Cleaning-^/
Headhouse (legs)
Export elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying^/
Cleaning—'
Headhouse (legs)
Tripper (gallery belts)
1.00
0.27
1.40
1.05
3.00
1.50
1.00
0.64
0.27
1.00
0.68
3.00
1.50
00
00
40
05
00
50
1.00
0.50
0.14
0.70
0.52
1.50
0.75
0.50
0.32
0.13
0.50
0.34
1.50
0.75
0.50
0.50
0.70
0.52
1.50
0.75
0.50
a_/ Emission factors are in terms of pounds of dust emitted per ton
of grain processed by each source.
b_/ Emission factors for drying are based on 1.8 Ib/ton for rack
dryers and 0.3 Ib/ton for column dryers prorated on the basis
of distribution of these two types of dryers in each elevator
category, as discussed in Reference 3.
_c/ Emission factor of 3.00 for cleaning is an average value which
may range from < 0.50 for wheat up to 6.00 for corn.
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Table 2. PARTICULATE EMISSION FACTORS FOR GRAIN ELEVATORS BASED ON
AMOUNT OF GRAIN RECEIVED OR SHIPPED^'
Emission factor Typical ratio of tons processed _ Emission factor
Type of source Ib/ton processed to tons received or shipped^ Ib/ton received or shipped
Terminal elevators
Unloading (receiving) 1.00 1.00 1.00
Loading (shipping) 0.27 1.00 0.27
Removal from bins (tunnel belt) 1.40 2.03 2.84
Drying^ 1.05 0.10 0.11
Cleaning^ 3.00 0.22 1.32
Headhouse (legs) 1.50 3.03 4.55
Tripper (gallery belt) 1.00 1.71 1.71
Country elevators
Unloading (receiving) 0.64 I.00 0.64
Loading (shipping) 0.27 1.00 0.27
Removal from bins 1.00 2.08 2.91
Drying^ 0.68 0.25 0.17
Cleaning^ 3.00 0.08 0.48
Headhouse (legs) 1.50 3.08 4.62
Export elevators
Unloading (receiving) 1.00 1.00 1.00
Loading (shipping) 1.00 1.00 1.00
Removal from bins (tunnel belt) 1.40 1.23 1.72
Drying^/ 1.05 0.01 0.01
Cleaning^ - - - ^QQ ^^ ^^
Headhouse (legs) 1.50 2.23 3.35
Tripper (gallery belt) 1.00 1.07 1.07
_a/ Assumed that over the long term the amount received Is approximately equal to amount shipped.
b/ See Note b/ In Table 1.
c/ See Note c/ In Table 1.
A/ Ratios shown are average values taken from a survey of many elevators across the U.S.— These ratios can be
considerably different for any individual elevator or group of elevators In the same locale.
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is not known and it is quite possible that all of this dust is eventually
emitted to the atmosphere due to subsequent external operations, internal
ventilation or other means.
Many elevators utilize control devices on at least some sources. In
the past, cyclones have commonly been applied to such sources as legs in
the headhouse and tunnel belt hooding systems. More recently, fabric fil-
ters have been utilized at many elevators on almost all types of sources.
However, some sources in grain elevators do present control problems. Con-
trol of loadout operations is one source that is difficult to control be-
cause of the problem of containment of the emissions. Probably the most
difficult source to control, because of the large flow rate and high mois-
ture content of the exhaust gases, is the dryers. Screen-houses or contin-
uously vacuumed screen systems are available for reducing dryer emissions
and have been applied at several facilities. Detailed descriptions of dust
control systems for grain elevator operations and their estimated costs
are contained in Ref. 2.
Grain Processing Operations - Grain processing operations include many of
the operations performed in a grain elevator in addition to milling and
processing of the grain. Qnission factors for different grain milling and
processing operations are presented in Table 3. Brief discussions of these
different operations and the methods used for arriving at the emission fac-
tor values shown in Table 3 are presented below.
Bnission factor data for feed mill operations are sparse. This is
partly due to the fact that many ingredients, whole grain and other dusty
materials (bran, dehydrated alfalfa, etc.), are received by both truck and
rail and several unloading methods are employed. However, some operations
(handling, shipping, and receiving) for a feed mill are similar to opera-
tions in a grain elevator, so an emission factor for each of these differ-
ent operations was estimated on this basis. The remaining operations were
estimated from the best information available..?.'
Three emission areas for wheat mill processing operations are grain
receiving and handling, cleaning house, and milling operations. Data from
a grain elevator study!/ were used to estimate emission factors for grain
receiving and handling. Data for the cleaning house were insufficient to
estimate an emission factor and information taken from Ref. 2 was used to
estimate the emission factor for milling operations. The large emission
factor for the milling operation is somewhat misleading because almost all
of the sources involved are equipped with control devices to prevent prod-
uct losses and fabric filters are widely used for this purpose.
Operations for durum mills and rye milling are similar to those of
wheat milling. Therefore, most of these emission factors are equal to those
for wheat mill operations.
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Table 3. PARTICULATE EMISSION FACTORS FOR
GRAIN PROCESSING OPERATIONsii2-*3-7
Emission
(uncontrolled except where indicated)
Type of source (Ib/ton) (kg/MT)
Feed mills
Receiving 1.30 0.65
Shipping 0.50 0.25
Handling 3.00 . 1.50 .
Grinding 0.10s 0.05s'
Pellet coolers 0.10s 0.05s
Wheat mills
Receiving 1.00 0.50
Precleaning and handling 5.00 2.50
Cleaning house
Millhouse 70.00 35.00
Durum mills
Receiving 1.00 0.50
Precleaning and handling 5.00 2.50
Cleaning house
Millhouse
Rye milling
Receiving 1.00 0.50
Precleaning and handling 5.00 2.50
Cleaning house
Millhouse 70.00 35.00
Dry corn milling
Receiving 1.00 0.50
Drying 0.50 0.25
Precleaning and handling 5.00 2.50
Cleaning house 6.00 3.00
Degerming and milling
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Table 3. (Concluded)
a,b/
Emission factor—*—
(uncontrolled except where indicated)
Type of source (Ib/ton) (kg/MT)
Oat milling
d/ d/
Total 2.50- 1.25-
Rice milling
Receiving 0.64 0.32
Handling and precleaning 5.00 2.50
Drying
Cleaning and millhouse
Soybean mills
Receiving 1.60 0.80
Handling 5.00 2.50
Cleaning
Drying 7.20 3.60
Cracking and dehulling 3.30 1.65
Hull grinding 2.00 1.00
Bean conditioning 0.10 0.05
Flaking 0.57 0.29
Meal dryer 1.50 0.75
Meal cooler 1.80 0.90
Bulk loading 0.27 0.14
Corn wet milling
Receiving 1.00 0.50
Handling 5.00 2.50
Cleaning 6.00 3.00
Dryers
Bulk loading
a/ Emission factors are expressed in terms of pounds of dust emitted
per ton of grain entering the plant (i.e., received), which is
not necessarily the same as the amount of material processed by
each operation.
b_/ Blanks indicate insufficient information.
£/ Controlled emission factor (controlled with cyclones).
d_/ Controlled emission factor (This represents several sources in one
plant; some controlled with cyclones and others controlled with
fabric filters.)
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The grain unloading, handling and cleaning operations for dry corn
milling are similar to1 those in other grain mills but the subsequent opera-
tions are somewhat different. Also, some drying of corn received at the mill
may be necessary prior to storage. An estimate of the emission factor for
drying was obtained from Ref. 2. Insufficient information was available to
estimate emission factors for degerming and milling.
Information necessary to estimate emissions from oat milling was un-
available. It was also felt to be unwise to attempt to use emission factor
data for other grains because handling of oats is reported to be dustier
than many other grains. The only emissions factor data that were available
were for controlled emissions..?/ An overall controlled emission factor of
2.5 Ib/ton was calculated from this data.
Bnission factors for rice milling were based on those for similar op-
erations in other grain handling facilities. Insufficient information was
available to estimate emission factors for drying, cleaning and mill house
operations.
Information taken from Ref. 2 was used to estimate emission factors
for soybean mills.
Information on corn wet-milling emission factors was unavailable in
most cases due to the wide variety of products and the diversity of opera-
tions. Receiving, handling and cleaning operations emission factors were
assumed to be similar to those for dry corn milling.
Many of the operations performed in grain milling and processing plants
are the same as those in grain elevators, so the control methods are similar.
As in the case of grain elevators, these plants often use cyclones or fabric
filters to control emissions from the grain handling operations (e.g., un-
loading, legs, cleaners, etc.). These same devices are also often used to
control emissions from other processing operations and a good example of
this is the extensive use of fabric filters in flour mills. However, there
are also certain sources within some milling operations that are not amena-
ble to use of these devices. Therefore, wet scrubbers have found some appli-
cation, particularly where the effluent gas stream has high moisture content.
Certain other sources have been found to be especially difficult to control,
and one of these is the rotary dryers in wet corn mills. Descriptions of the
emission control systems that have been applied to sources within the grain
milling and processing industries are contained in Ref. 2.
10
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BACKGROUND .AND SUPPORT INFORMATION FOR EMISSION FACTORS FOR FEED AND
GRAIN MILLS AND ELEVATORS
General
Grain elevators are transfer and storage areas for grain and are usu-
ally classified as either country, terminal, or export elevators. Country
elevators generally receive grains as they are harvested from fields within
a 10- to 20-mile radius of the elevator. The country elevators unload, weigh
and store grain as it is received from the farmer. In addition, the country
elevator may dry or clean the grain before it is shipped to the terminal
elevators or processors.
Terminal elevators receive most of their grain from country elevators
and ship to processors, other terminals, and exporters. The primary function
of a terminal elevator is to store grain in quantity without deterioration
and to bring it to commercial grade so as to conform to the needs of buyers.
As with country elevators, terminals dry, clean and sort grain. In addition,
they can blend grain to meet buyer specifications.
Export elevators are similar to terminal elevators with the exception
that they mainly load grain on ships for export.
The other types of operations involved in the processing of grain, in
grain and feed plants, range from very simple mixing steps to complex pro-
cesses which are characteristic of industrial processing plants. Included
are such diverse processes as: (a) simple mixing processes in feed mills,
(b) grain milling in flour mills, (c) solvent extracting in soybean pro-
cessing plants, and (d) a complex series of processing steps in a corn wet-
milling plant.
Emissions and Controls
Grain handling, milling and processing include a variety of operations
from the initial receipt of the grain at either a country or terminal eleva-
tor to the delivery of a finished product. Flour, livestock feed, soybean
oil and corn syrup are among the products produced from plants in the grain
and feed industry. Emissions from the feed and grain industry can be sepa-
rated into two general areas, those occurring at grain elevators and those
occurring at grain processing operations.
Grain Elevators - Grain elevator emissions can occur from many different
operations in the elevator, including unloading (receiving), loading (ship-
ping), drying, cleaning, headhouse (legs), tunnel belt, and belt trippers
(primarily for terminal and export elevators). Emissions factors for sev-
eral of these operations are presented in Table 4.
11
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Table 4. PARTICULATE EMISSION FACTORS FOR GRAIN ELEVATORS
Type of source
Terminal elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying
Cleaning
Headhouse (legs)
Tripper (gallery belt)
Country elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying
Cleaning
Headhouse (legs)
o/
Export elevators"
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying
Cleaning
Headhouse (legs)
Tripper (gallery belt)
Emission factor^/
(uncontrolled)
Ib/ton kg/ma
1.00*'
°'27d7
1.40^
1.03=
3.0^,
l.50n
1.00*'
,
1.00*
0.681'
3.00='
1.503'
1.00 .
LOO*'
1.40
1.05
3.00
1.50
1.00
0.50
0.14
0.70
0.52
1.50
0.75
0.50
0.32
0.13
0.50
0.34
1.50
0.75
0.50
0.50
0.70
0.52
1.50
0.75
0.50
References
al Emission factors are in terms of pounds of dust emitted per ton of grain processed by
each source. .
J>/ Emission factor of 1.00 Ib/ton for unloading is based on Kansas City elevator study.—
Table 5 shows the values for truck unloading (0.64) and car unloading (1.30). These
data are supported by other data in Reference 2. .
_c/ The emission factor for loading was taken from the Kansas City elevator study" which
shows a value of 0.27 Ib/ton for car loading (Table 5). Emission factor for truck
loading was not determined but Is not expected to be significantly different.
d/ Emission factor of 1.40 Ib/ton is based on tunnel belt emission factor of 1.40 deter-
mined In the Kansas City elevator study (Table 5).-='
el Emission factor of 1.05 Ib/ton for drying was based on dryer emissions, discussed in
Appendix A of 0.3 Ib/ton for column dryers and 1.8 for rack dryers. Other survey data
Indicate ratio of column to rack dryers at terminal elevators .is about 1:1, so an av-
erage emission factor of 1.05 Ib/ton was used.
_f/ An emission factor of 5.78 Ib/ton for cleaning of corn is shown In Table 5, whereas
data in Table 6 show a much lower value of 0.34 Ib/ton for wheat and smaller grains.
Therefore, an average value of 3.00 Ib/ton was selected. Because the actual emission
factor is dependent on the type of grain, It would be more accurate to use the appro-
priate value for wheat or corn when possible.
£/ An emission factor of 1.5 Ib/ton for the headhouse is from the Kansas City elevator
studyi' and Is shown by Table 5. This value Includes garner and .scale.
h/ The emission factor for the tripper of 1.00 Ib/ton is an estimate based on factors for
other sources and observations of tripper emissions.
il The emission factor of 0.64 Ib/ton for truck unloading was taken from the Kansas City
elevator study (Table 5).-i' The value of 0.09 Ib/ton shown In Table 6 is lower but
was for only one grain (wheat). This is consistent with other data.in Reference 1 in
which short-term tests showed that the emission factor for unloading of wheat may
vary from 0.08 to 1.06 Ib/ton.
J/ It was assumed that the emission factor for loading at country elevators would be the
same as that for terminal elevators, because no other data was available.
Jj/ An emission factor of 1.00 Ib/ton is based on the average of data for country elevators
shown in Table 6.
ll Emission factor of 0.68 Ib/ton for drying at country elevators is discussed In Appendix
A which showed 0.3 Ib/ton for column dryers and 1.8 Ib/ton for rack dryers. Survey
data Indicated that 75% of dryers at country elevators were column type so an emis-
sion factor of 0.68 Ib/ton was used.
ml An emission factor of 6.00 Ib/ton for cleaning Is based on the Kansas City elevator
studyi' which showed a value of 5.78 Ib/ton (for corn) in Table 5.
nl There Is a Large disparity in the data shown In Table 6 for headhouse (leg) emission
factors. However, the average of these data (1.98 Ib/ton) is reasonably close to the
long-term value of 1.50 Ib/ton shown in Table 5.
ol Emission factors for all sources are assumed to be the same as for terminal elevators,
except ship loading.
j>/ An emission factor of 1.0 Ib/ton for ship loading is based on one test on ship loading
as a port elevator in Seattle (EPA Emission Test Report 78-ORN-8).
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Meager specific emission test data are available from which uncontrolled
emission factors could be computed. Therefore most of the factors for termi-
nal and export elevators are based on results reported in Ref. 1, as summa-
rized in Table 5. Recent EPA test results and some emission test reports from
North Dakota (Table 6) were used in deriving emission factors for country
elevators. These test reports are short-term emission measurements at a few
country elevators, which were compared with the long-term test data for the
terminal elevatori/ in order to select emission factors that may be appro-
priate for country elevators. The emission factor for drying is based mainly
on data contained in Refs. 2 and 3, as discussed in Appendix A of this re-
port. All of these emission factors are approximate average values intended
to be representative of a variety of grain types but, as noted in Table 4
and in the references, actual emission factors for a specific source could
be different, depending on the type of grain (e.g., cleaning) and many other
factors.
The emission factors shown in Table 4 represent the amount of dust
generated per ton of grain processed through each of the designated opera-
tions (i.e., uncontrolled emission factors). Amounts of grain processed
through each of these operations in a given elevator are dependent on such
factors as the amount of grain turned (interbin transfer), amount dryed,
and amount cleaned. Because the amount of grain passing through each opera-
tion is often difficult to determine, it may be more useful to express the
emission factors in terms of the amount of grain shipped or received, assum-
ing these amounts are about the same over the long term. Emission factors
from Table 4 have been modified accordingly and are shown in Table 7 along
with the appropriate multiplier that was used as representative of typical
ratios of throughput at each operation to the amount of grain shipped or
received. This ratio is an approximate value based on average values for
turning, cleaning, and drying in each type of elevator, as explained in
Table 8. However, operating practices in individual elevators are different,
so these ratios, like the basic emission factors themselves, would be more
valid for a group of elevators rather than individual elevators.
The factors given in the tables should not be added together in an at-
tempt to obtain a single emission factor value for grain elevators because
in most elevators some of the operations are equipped with control devices
and some are not. Therefore, any estimation of emissions must be directed
to each operation and its associated control device, rather than to the el-
evator as a whole, unless the purpose was to estimate total potential (i.e.,
uncontrolled) emissions. An example of the use of emission factors in making
an emission inventory is contained in Ref. 3.
Some of the operations listed in the tables, such as the tunnel belt
and belt tripper, are internal or in-house dust sources which, if uncon-
trolled, might show lower than expected atmospheric emissions because of
internal settling of dust. The reduction in emissions via internal settling
is not known and it is quite possible that all of this dust is eventually
emitted to the atmosphere due to subsequent external operations, internal
ventilation or other means.
13
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Table 5. BEST AVERAGE VALUE OF LONG-TERM
COMPOSITE EMISSION FACTORS FOR A
TERMINAL ELEVATOR (LB/TON}!/
Emission factor
Operation (Ib/ton of grain processed)
Truck unloading
Car unloading
Car loading
Corn cleaner
Gallery belt
Tunnel belt
Headhouse
0.64
1.30
0.27
5.78
0.11
1.40
1.49
Table 6. SUMMARY OF UNCONTROLLED EMISSION FACTOR DATA
FROM TESTS AT COUNTRY ELEVATORS
Source
Unloading (trucks)
Removal from bins (tunnel belt
hoods and leg boots, etc.)
Cleaning
Headhouse (distributor and
legs, but also including
dump pits)
(legs only)
Emission factor (Ib/ton)
and grain type
0.09-/ (wheat)
0.68, 0.37-/ (wheat)
2.72-' (soybeans)
0.91-/ (corn)
0.63- (milo)
1.06 avg.
0.18*'
0.40-/
0.431/
(whea t)
(not identified)
(wheat and rye)
0.34 avg.
0.14-^ (wheat)
0.10^-' (not identified)
0.48^/ (wheat, oats, barley)
1.52-/ (wheat)
3.47^ (milo)
6.15~ (soybeans)
1.98 avg.
14
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Table 7. PARTICULATE EMISSION FACTORS FOR GRAIN ELEVATORS
BASED ON AMOUNT OF GRAIN RECEIVED OR SHIPPED^/
Emission Factor _ Typical ratio of Tons Processed
Type of Source
Terminal Elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying
Cleaning
Headhouse (legs)
Tripper (gallery belt)
Country Elevators
Unloading (receiving)
Loading (shipping)
_. Removal from bins
r\
Drying
Cleaning
Headhouse (legs)
Export Elevators
Unloading (receiving)
Loading (shipping)
Removal from bins (tunnel belt)
Drying
Cleaning
Headhouse (legs)
Tripper (gallery belt)
Ib/ton processed to Tons Received or Shipped3^"./
1.00
0.27
1.40
1.05
3.00
1.50
1.00
0.64
0.27
1.00
0.68
3.00
1.50
1.00
1.00
1.40
1.05
3.00
1.50
1.00
1.00
1.00
2.03
0.10
0.22
3.03
1.71
1.00
1.00
2.08
0.25
0.08
3.08
1.00
1.00
1.23
0.01
0.15
2.23
1.07
_ Emission Factor
Ib/ton received or shipped
1.00
0.27
2.84
0.11
0.66
4.55
1.71
0.64
0.27
2.08
0.17 .
0.24
4.62
1.00
1.00
1.72
0.01
0.45!
3.35
1.07
_a/ Assumed that over the long term the amount received is approximately equal to amount shipped.
b/ See Table 8 for explanation of ratios used. These are typical values based on averages taken from a survey of many
elevators across the U.S. and can be considerably different for any individual elevators or group of elevators
in the same locale.
-------
Table 8. AVERAGE VALUES USED FOR RATIO OF TONS
PROCESSED TO TONS SHIPPED OR RECEIVED
Ratio of Grain Throughput to Grain Received or
Emission Sources
Terminal Elevators
Unloading
Loading
Removal from bins
Drying
Cleaning
Headhouse
Tripper
Country Elevators
Unloading
Loading
Removal from bins
Drying
Cleaning
Headhouse
Export Elevators
Unloading
Loading
Removal from bins
Drying
Cleaning
Headhouse
Tripper
for basic elevator
Unloading Loading
1.00
1.00
1.00 +
1.00 + 1.00 +
1.00 +
1.00
1.00
1.00 +
1.00 + 1.00 +
1.00
1.00
1.00 +
1.00 + 1.00 +
1.00 +
functions
Turning
0.71
0.71
0.71
0.75
0.75
0.07
0.07
0.07
listed below^'
Drying
+ 0.10
0.10
+ 0.10
+ 0.25
0.25
+ 0.25
+ 0.01
0.01
+ 0.01
Shipped
Cleaning
ss
=
+ 0.22
=
0.22
+ 0.22
=
=
=
+ 0.08
=
0.08
+ 0.08
=
=
+ 0.15
=:
0.15
+ 0.15
=
To tal^/
1.00
1.00
2.03
0.10
0.22
3.03
1.71
1.00
1.00
2.08
0.25
0.08
3.08
1.00
1.00
1.23
0.01
0.15
2.23
1.07
b/
Values derived from information and data in Reference 3 and are based on a survey of many elevators across
the U.S. These ratios may therefore be considerably different for an individual elevator or group of ele-
vators in the same locale.
"Total" represents the overall average ratio of grain throughput to grain received or shipped for each emis-
sion source due to all basic elevator functions which involve that source.
-------
As mentioned above, many elevators utilize control devices on at
least some sources. In the past, cyclones have commonly been applied to
such sources as legs in the headhouse and tunnel belt hooding systems.
More recently, fabric filters have been utilized at many elevators on al-
most all sources. However, some sources in grain elevators do present con-
trol problems. Control of load-out operation is one of the more difficult
sources to control because of the problem of containment of the emissions.
Probably the most difficult source to control, because of the large flow
rate and high moisture content of the exhaust gases, is the dryers. Screen-
houses or continuously vacuumed screen systems are available for reducing
dryer emissions and have been applied at several facilities. Detailed de-
scription of dust control systems for grain elevator operations and their
estimated costs are contained in Ref. 2.
Grain Processing Operations - Grain processing operations include many of
the operations performed in a grain elevator in addition to milling and
processing of the grain. Emission factors for different grain milling and
processing operations are presented in Table 9. Brief discussions of these
different operations and the methods used for arriving at the emission fac-
tor values shown in Table 9 are presented below. More detailed discussion
and derivation of the emission factors shown in Table 9 are presented in
Appendix B.
Emission factor data for feed mill operations are sparse. This is
partly due to the fact that many ingredients, whole grain and other dusty
materials (bran, dehydrated alfalfa, etc. ), are received by both truck and
rail and several unloading methods are employed. However, some operations
(handling, shipping, and receiving) for a feed mill are similar to opera-
tions in a grain elevator, so an emission factor for each of these differ-
ent operations was estimated on this basis. The remaining operations were
estimated from the best information available.^'
Three emission areas for wheat mill processing operations are grain
receiving and handling, cleaning house, and milling operations. Data from
a grain elevator studyJ/ were used to estimate emission factors for grain
receiving and handling. Data for the cleaning house were insufficient to
estimate an emission factor and information taken from Ref. 2 was used to
estimate the emission factor for milling operations. The large emission
factor for the milling operation is somewhat misleading because almost all
of the sources involved are equipped with control devices to prevent prod-
uct losses and fabric filters are widely used for this purpose.
Operations for durum mills and rye milling are similar to those of
wheat milling. Therefore, most of these emission factors are equal to those
for wheat mill operations.
17
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Table 9. PARTICULATE EMISSION FACTORS FOR
pRAIN PROCESSING OPERATIONS^/
Emission factors a,b,c/
(uncontrolled except where indicated)
Type of source (Ib/ton) (kg/MT)
Feed Mills
Receiving 1.30 0.65
Shipping 0.50 0.25
Handling 3.00 1.50
Grinding 0.104/ 0.05^/
Pellet coolers O.lOd/ O.OS-^/
Wheat Mills
Receiving 1.00 0.50
Precleaning and handling 5.00 2.50
Cleaning house
Millhouse 70.00 35.00
Durum Mills
Receiving 1.00 0.50
Precleaning and handling 5.00 2.50
Cleaning house
Millhouse
Rye Milling
Receiving 1.00 0.50
Precleaning and handling 5.00 2.50
Cleaning house
Millhouse 70.00 35.00
Dry Corn Milling
Receiving 1.00 0.50
Drying 0.50 0.25
Precleaning and handling 5.00 2.50
Cleaning house 6.00 3.00
Degenning and milling
18
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Table 9.' (Concluded)
Emission fapfnr.g a,b,d/
(uncontrolled except where indicated)
Type of source (Ib/ton) (kg/MT)
Oat Milling
Total 2.50^ 1.25-7
Rice Milling
Receiving 0.64 0.32
Handling and precleaning 5.00 2.50
Drying
Cleaning and millhouse
Soybean Mills
Receiving 1.60 0.80
Handling 5.00 2.50
Cleaning
Drying 7.20 3.60
Cracking and dehulling 3.30 1.65
Hull grinding 2.00 1.00
Bean conditioning 0.10 0.05
Flaking 0.57 0.29
Meal dryer 1.50 0.75
Meal cooler 1.80 0.90
Bulk loading 0.27 0.14
Corn Wet Milling
Receiving 1.00 0.50
Handling 5.00 2.50
Cleaning 6.00 3.00
Dryers
Bulk loading
^/ See Appendix B.
b/ Emission factors are expressed in terms of pounds of dust emitted per ton
of grain entering the plant (i.e., received), which is not necessarily
the same as the amount of material processed by each operation.
_c/ Blanks indicate insufficient information.
d/ Controlled emission factor (controlled with cyclones).
_§/ Controlled emission factor (This represents several sources in one plant;
some controlled with cyclones and others controlled with fabric filters.)
19
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The grain unloading, handling and cleaning operations for dry corn
milling are similar to those in other grain mills but the subsequent opera-
tions are somewhat different. Also, some drying of corn received at the mill
may be necessary prior to storage. An estimate of the emission factor for
drying was obtained from Ref. 2. Insufficient information was available to
estimate emission factors for degerming and milling.
Information necessary to estimate emissions from oat milling was un-
available. It was also felt to be unwise to attempt to use emission factor
data for other grains because handling of oats is reported to be dustier
than many other grains. The only emissions factor data that were available
were for controlled emissions.-^' An overall controlled emission factor of
2.5 Ib/ton was calculated from this data.
Emission factors for rice milling were based on those for similar op-
erations in other grain handling facilities. Insufficient information was
available to estimate emission factors for drying, cleaning and mill house
operations.
Information taken from Ref. 2 was used to estimate emission factors
for soybean mills.
Information on corn wet-milling emission factors was unavailable in
most cases due to the wide variety of products and the diversity of opera-
tions. Receiving, handling and cleaning operations emission factors were
assumed to be similar to those for dry corn milling.
20
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REFERENCES
1. Gorman, P. G., "Potential Dust Emission From a Grain Elevator In
Kansas City, Missouri," Final Report, prepared for Environmental
Protection Agency, May 1974.
2. Shannon, L. J., R. W. Gerstle, P. G. Gorman, D. M. Epp, T. W. Devitt,
and R. Anick, "Emission Control in the Grain and Feed Industry
Volume I - Engineering and Cost Study," Final Report by Midwest
Research Institute prepared for Environmental Protection Agency,
Document No. EPA-450/3-73-003a, December 1973.
3. Shannon, L. J., P. G. Gorman, M. P. Schrag, and D. Wallace, "Mis-
sion Control in the Grain and Feed Industry Volume II - Emission
Inventory," Final Report by Midwest Research Institute prepared
for Environmental Protection Agency, July 1974.
4. Maxwell, W. H., "Stationary Source Testing of a Country Grain Ele-
vator at Overbrook, Kansas," Report prepared by Midwest Research
Institute for Environmental Protection Agency, EPA Contract No.
68-02-1403, February 1976.
5. Maxwell, W. H., "Stationary Source Testing of a Country Grain Ele-
vator at Great Bend, Kansas," Report prepared by Midwest Research
Institute for Environmental Protection Agency, EPA Contract No.
68-02-1403, April 1976.
6. Belgea, F. J., "Cyclone Emissions and Efficiency Evaluation," Report
submitted to North Dakota State Department of Health on tests at
an elevator in Edenburg, North Dakota, by Pollution Curbs, Inc.,
St. Paul, Minnesota, March 10, 1972.
7. Trowbridge, A. L., "Particulate Emission Testing - ERG Report No.
' 4-7683," Report submitted to North Dakota State Department of Health
on Tests at an elevator in Egeland, North Dakota, by Environmental
Research Corporation, St. Paul, Minnesota, January 16, 1976.
8. Belgea, F. J., "Grain Handling Dust Collection Systems Evaluation
for Farmers Elevator Company, Minot, North Dakota," Report sub-
mitted to North Dakota State Department of Health, by Pollution
Curbs, Inc., St. Paul, Minnesota, August 28, 1972.
9. Belgea, F. J., "Cyclone Emission and Efficiency Evaluation," Report
submitted to North Dakota State Department of Health on tests at
an elevator in Thompson, North Dakota, by Pollution Curbs, Inc.,
St. Paul, Minnesota, March 10, 1972.
21
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APPENDIX A
EMISSION FACTORS FOR GRAIN DRYERS AT GRAIN ELEVATORS
GRAIN DRYER EMISSION FACTORS
A quantitative assessment of emissions from grain dryers is difficult,
primarily because of lack of available data. However, these data and
other information have indicated that the emission rate from any given
installation is dependent upon the dryer configuration, i.e., rack or
column; the type of grain being processed, i.e., corn, soybeans, wheat;
the foreign material present in the incoming grain, i.e., dust, chaff,
"beeswing" hulls, etc.; and the amount of moisture removed which af-
fects throughput.
The large volumes of air passed through the grain, the large cross-
sectional area through which the air is exhausted and the wide par-
ticle size distribution of the effluent contribute to sampling dif-
ficulties. The absence of an acceptable test method makes comparisons
between reported dryer emission tests highly uncertain.
A compilation of the available data on emissions test for rack and column
type dryers is presented in Table A-l and, based on these data, average
values for the uncontrolled emission factors were selected:
Rack Dryers - 1.8 Ib/ton
Column Dryers - 0.3 Ib/ton
Because of the small amount of available data, spread in these data,in-
adequate information regarding specific test methods, use of different
sampling trains, and the lack of complete information regarding foreign
material and moisture differential, these emission factors should only
be considered as indicative of possible average emissions and not ab-
solute numbers for individual dryers.
23
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Table A-l. SUMMARY OF AVAILABLE EMISSION FACTOR DATA
FOR GRAIN DRYERS (UNCONTROLLED)
Rack
Throughput
(bu/hr)
1,000
2,000
500
1,500
1,800
dryers
Emission factor
(Ib/ton)
3.7s/
2.3s/
1.2*/
0.&
1>0b/
Avg. =1.8 Ib/ton
Column dryers
Throughput
(bu/hr)
400
1,000
3,000
Avg
Emission factor
(Ib/ton)
0.23s/
0.21-/
__^__^^__
. = 0.3 Ib/ton
aj Reference 2.
b/ Private communication.
24
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APPENDIX B
DERIVATION OF EMISSION FACTORS FOR GRAIN PROCESSING
OPERATIONS (as shown in Table 9)
FEED MILLS
Receiving
As stated in Reference 2 (p. 159) the ingredient receiving area repre-
sents the most serious dust emission problem in most feed mills. Emis-
sion factor data for this operation are sparse, owing partly to the fact
that many ingredients; whole grain and other more dusty materials (bran,
dehy alfalfa, etc.), are received, by both truck and rail and several
unloading methods are employed. For these reasons, an average emission
factor would be difficult to determine, at least as far as whole
grains are concerned, so an emission factor for the unloading operation
only has been estimated as 1.30 Ib/ton. This was the value determined
in the Kansas City elevator study!./ for car unloading and may be re-
presentative of feed mills and hopefully reflects the fact that some
ingredients tend to be more dusty than whole grains.
Shipping
Most feed mills ship the bulk feed by truck, but some are also shipped in
bags by rail and truck. Reference 2 (p. 166) states that loadout is a
major source of dust emissions but little emission factor data are avail-
able. An emission factor of 0.27 Ib/ton was determined for car loading
of grain in the Kansas City elevator study.—' It is assumed that bulk
loading of feed mill products would tend to be more dusty than whole
grain loading. Therefore, an emission factor of 0.5 Ib/ton has been
estimated for this operation.
Handling Operations (transfer points, garner and scale, legs)
No data were available for the internal handling operations in feed
mills. However, it would be expected that they are somewhat similar to
25
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those in grain elevators. The Kansas City elevator study—' showed that
the most significant of these operations was the legs, having an emis-
sion factor of 1.49 Ib/ton. The tunnel belt factor of 1.40 Ib/ton is
similar but feed mill operations are such that this may not be a com-
parable operation. However, all material in a feed mill would be ex-
pected to pass through a leg at least twice from unloading to shipping.
Therefore, an overall average emission factor for feed mill handling
operations has been estimated as 3.0 Ib/ton.
Grinding
Whole grains received at feed mills must be ground and the associated
product recovery cyclone is the major dust source in this grain prep-
aration operation. Because of the wide variation in grains and
grinders used, an average emission factor would be difficult to deter-
mine. A small amount of data presented in Reference 2 (p. 163) in-
dicated that controlled emissions may range from 0.02 to 0.2 Ib/ton.
Considering these facts, and lack of other data, an average controlled
emission factor of 0.1 Ib/ton has been estimated, assuming it is to be
representative of the industry as a whole.
Pellet Coolers
The only available emission factor data for this operation was contained
in Reference 2 (pp. 164-167) and indicated that the uncontrolled emis-
sion factor was quite high (5 to 50 Ib/ton) but that the cyclones were
very efficient (92 to 99.9%). The data on p. 164 show considerable dif-
ference in controlled emission factors for horizontal coolers and column
coolers. Distribution of these two types of coolers within the industry
is not known but our observations indicate that column coolers are quite
common. For this reason, a controlled emission factor of 0.1 Ib/ton
has been estimated.
WHEAT MILLS
Processing operations were discussed in Reference 2 (p. 207) and identi-
fied three emission areas: grain receiving and handling, cleaning
house, and milling operations. Emission factors and calculation of
emissions for sources within each of these operations is discussed be-
low.
Receiving
It would be expected that receiving of wheat would be similar in emissions
to that for terminal grain elevators (0.64 and 1.30 Ib/ton).—' Data on
26
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p. 122 of Reference 2 presents controlled emission factors for fabric fil-
ters but it is difficult to use these data in estimating an uncontrolled
factor. Therefore, the data from Reference 1 had to be used, and an average
factor of 1.0 Ib/ton was selected for receiving by trucks, cars, and barges^
Freeleaning and Handling
Very little data on uncontrolled emissions from precleaning were avail-
able, but it is assumed to consist primarily of scalping type operations,
which should be a minor source in comparison with handling operations.
Handling consists of legs, transfer points, garner and scale and tripper,
etc. Usable data on uncontrolled emission factors for these sources in
flour mills were lacking, so the data from Reference 1 had to be used,
even though it was for a grain elevator and did not include a tripper.
However, it did include a tunnel belt and it is also known that in a
flour mill the grain would pass through the leg twice (once when re-
ceived and once when transferred to cleaning house). Therefore, a
cumulative emission factor of 5.0 Ib/ton was estimated for all pre-
cleaning and handling operations.
Cleaning House
Cleaning is accomplished by a variety of means but often includes air
aspiration to remove lighter impurities (dust) as well as disc separators
and scourers. Each of these can be a source of dust emissions but only
a small amount of emission data on cyclone controlled sources were avail-
able in Reference 2 (p. 210). Therefore, it was not feasible to cal-
culate an emission factor for the cleaning house.
Mill House
Operations in the mill house are complex, and again, very little emission
data are available. Reference 2 (p. 209) cites one report which indicated
that dust generated in roller mills may average 2.1 Ib/bu (70 Ib/ton).
This source and the purifiers might therefore account for more than 70
Ib/ton. This emission factor is larger than the one for precleaning and
handling and may be erroneously high but it was the only data available.
It should be noted that because of the product value these emissions
are controlled, primarily with fabric filters.
27
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DURUM MILLS
The sources of air pollution in a durum mill parallel those of a flour
mill and fall into the three main categories of receiving and handling
operations, cleaning-house, and milling operations. Rate of emission
for durum mill operations are limited but since the processing operations
are similar to those of a flour mill, the rates are expected to be
similar (Reference 2, p. 215). However, in the mill section one of the
primary purposes is to produce middlings rather than flour so the break
rolls are different. Because of this, it is assumed that the emission
factor of 70 Ib/ton used for the mill house in flour mills may not be
applicable to durum mills. Therefore, the same emission factors for
flour mills were assumed to apply, but the emission factor for milling
operations was not estimated.
RYE MILLING
The milling procedure for rye consists of the same processing steps as
wheat milling (Reference 2, p. 221) and air pollution sources parallel
those in a wheat mill. Very little emission factor data were available
for rye milling. Some data on certain milling operations (Reference 2,
p. 226) indicate a controlled emission factor of about 1 Ib/ton. This
is equivalent to an uncontrolled emission factor of 10 Ib/ton, assuming
cyclone efficiencies of 9070. However, these data do not include break
rolls and other operations so the factor of 70 Ib/ton used for wheat
milling was assumed to be applicable to rye. This factor, and the
others for wheat milling were assumed to be the same for rye milling.
DRY CORN MILLING
The grain unloading, handling, and cleaning operations are similar to
those in other grain mills but the subsequent operations are somewhat
different (Reference 2, p. 216). Very little emission factor data were
available for dry corn milling, except for some controlled emission
factors tabulated in Reference 2 (pp. 222, 223).
Receiving
As in the case of flour mills, an average emission factor of 1.00 Ib/ton
has been used for the receiving operation.
Drying
Some drying of corn received at the mill may be necessary prior to storage.
Types of dryers used (rack or column) is not known, but about 50% use the
28
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Day-Vac system. For this reason, an emission factor of 0.5 Ib/ton was
used based on dryer emission factors discussed in Appendix A.
Freeleaning and Handling
As explained in the section on flour mills, an average emission factor
of 5.0 Ib/ton was used for the precleaning and handling operations.
Cleaning House
An emission factor of 5.78 Ib/ton was determined for a grain elevator
corn cleaning operation.!./ Also, Reference 2 (p. 222) shows an emis-
sion factor of 0.0015 Ib/bu (0.06 Ib/ton) for a cleaning house control-
led by a fabric filter. If the FF were 99% efficient, the equivalent
uncontrolled factor would be 6.0 Ib/ton, which agrees closely with the
previous factor of 5.78 Ib/ton.
Degerming and Milling
Emission factor data were not available.
OAT MILLING
Most of the information necessary for estimating emission factors was
not available. It was felt to be unwise to attempt to use emission
factor data for other grains because handling of oats is reported to be
dustier than many other grains. The only emission factor data that
were available contained controlled emission factors only (Reference 2,
p. 236) which can be used to calculate an overall factor of 0.04 Ib/bu
or 2.5 Ib/ton. It is not known if these data, for one mill, included
most major dust sources nor is it known if this plant, and the control
devices used (cyclones and fabric filters), are representative of the in-
dustry. However, both of the above were assumed to be true, and the total
controlled emission factor of 2.5 Ib/ton was used.
RICE MILLING
Emission factor data for rice milling operations are meager. Emission
sources associated with receiving, cleaning and storage are similar
to those involved with all grain [processing but it is not known if
rice emits more or less dust than other grains in these operations.
However, emission factors for other grains were used.
29
-------
Receiving
Data in Reference 2 (p. 471) indicate that most rice is received by
truck. An emission factor for truck unloading of 0.64 Ib/ton was
assumed based on data for a terminal grain elevator.!/
Handling and Precleaning
As was explained in the section on wheat mills, a cumulative emission
factor of 5.0 Ib/ton has been assumed for the similar operations in
a rice mill.
Drying
Observation of rice dryers indicates that the emission factor may be
considerably higher than for drying of other grains but supporting
data were not available.
Cleaning and Mill House
Because of the lack of data, no estimate of the emission factor could
be made.
SOYBEAN MILLS
Receiving
Data in Reference 2 (p. 251) indicate an average controlled emission
factor for a truck dump pit of 0.017 Ib/ton, or an uncontrolled factor
of 1.5 Ib/ton assuming 9970 efficiency for the fabric filter control
device. This is in good agreement with data in Reference 1 for soybeans
which showed 1.63 Ib/ton for truck unloading and 1.51 Ib/ton for car
unloading. Therefore, an emission factor of 1.6 Ib/ton was used for
soybean receiving.
Handling
No specific information was available on emission factors for soybean
handling operations. Even though the emissions from soybeans may be
higher than other grains the cumulative factor of 5.00 Ib/ton, as dis-
cussed in the wheat milling section, was used.
30
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Cleaning
No information was available on the cleaning of soybeans although it is
suggested that it would be at least as much as the 6.00 Ib/ton discussed
in the section on dry corn milling.
Drying
Soybean plants do dry the feed to the flaking mill and observations have
indicated that the emission factor for drying of soybeans at soybean
mills may be higher than the average factors discussed in Appendix A.
The only data available on soybean dryers are contained in Reference 2
(p. 255) and have been used to calculate uncontrolled emission factors
ranging from 4.2 to 80 Ib/ton. The value of 80 Ib/ton is very high
but even disregarding this value, the average factor is 7.2 Ib/ton.
Cracking (and dehulling)
Data presented in Reference 2 (p. 256) show that the controlled emission
factor for cracking and dehulling operations is on the order of 0.01
Ib/bu, or 0.33 Ib/ton. If one assumes 90% efficiency for the cyclone
control devices, the uncontrolled emission factor would be 3.3 Ib/ton.
Hull Grinding
Controlled emission factors for hull grinding in Reference 2 (p. 256)
show an average, for three reported values, of 0.0055 Ib/bu or 0.18 Ib/ton.
Again assuming 90% efficiency for the cyclone control devices, the un-
controlled emission factor would be approximately 2.0 Ib/ton.
Bean Conditioning
Reference 2 (p. 256) shows a cyclone controlled emission factor of
0.0003 Ib/bu or 0.01 Ib/ton. Assuming 90% cyclone efficiency, the
uncontrolled emission factor is 0.1 Ib/ton.
Flaking
A total of four controlled emission factors for flaking are presented in
Reference 2 (pp. 252, 256) and show an average of 0.0017 Ib/bu or 0.057
Ib/ton. These were each cyclone controlled, so assuming 90% efficiency,
the uncontrolled emission factor would be 0.57 Ib/ton.
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Meal Dryer
Cyclone controlled emission factor for meal dryers was presented in
Reference 2 (pp. 252, 256) and showed a range of 0.003 to 0.0128 Ib/bu
with an average of 0.0045 Ib/bu or 0.15 Ib/ton. Again assuming 907,
efficiency for the cyclones, the uncontrolled factor would be 1.5 Ib/ton.
Meal Cooler
Only one cyclone controlled emission factor was available (Reference 2,
p. 252); 0.0056 Ib/bu or 0.18 Ib/ton. Assuming 90% efficiency for the
cyclone, the uncontrolled factor would be 1.8 Ib/ton.
Bulk Loading
No emission factor data were available for meal loading. However,
observation of these operations indicates that it may be about the
same as loading grain at elevators or about 0.27 Ib/ton.—'
CORN WET MILLING
Receiving
Corn is received by cars and trucks and, as was done for dry corn mills,
an average emission factor of 1.0 Ib/ton was used.
Handling
Emission factors specifically applicable to handling of corn at wet corn
mills are not available. However, as was done on dry corn mills, an
average cumulative emission factor of 5.0 Ib/ton was used.
Cleaning
An emission factor of 6.0 Ib/ton for corn cleaning, as developed in the
section on dry corn mills, was used.
Dryers
Feed, gluten and germ dryers are a major source of emissions from wet
corn mills but emission factor data are lacking.
Bulk Loading
Bulk loading of products is another potential source of emissions but no
emission factor data are available.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
3. RECIPIENT'S ACCESSION"NO.
4. TITLE AND SUBTITLE
Source.Test Evaluation For Feed And Grain Industry
5. REPORT DATE
December 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
M.P. Schrag, P.G. Gorman and W.H. Maxwell
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-1403
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environment Protection Agency
Office of Air Quality Planning and Standards
Monitoring and Data Analysis Division
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report is a revised version of a previous document prepared by MRI for
EPA entitled "Emission Factor Development for the Feed and Grain Industry"
(EPA-450/3-75-054) dated October 1974. The subject of this report is emission
factors for grain elevators and other feed and grain operations (excluding alfalfa
dehydration).
Major portions of the information and data presented in this report are the
same as that in the previous document. The primary difference is the revision of
some data for country elevators based on recent EPA tests conducted at two elevators
in Kansas, and other reports made available through the North Dakota State Department
of Health. To our knowledge, no other new information or data have become available
for reevaluation of emission factors for the subject sources in the feed and grain
industry.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Emission Factors
Grain Elevators
Grain Processing
Particulate Emission Factors
8. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (This Report)
Mnr1a<;«Hf i pH
21. NO. OF PAGES
37
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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