United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-86/052 Mar. 1987
&EPA Project Summary
VOC Emission Factors for NAPAP
Emission Inventory
J. H. Stalling, M. A. Bloomhardt, and I. M. McKenzie
As part of the National Acid Precipita-
tion Assessment Program (NAPAP), the
U.S. Environmental Protection Agency
(EPA) identified the need to generate
emission factors for volatile organic
compound (VOC) emissions for a num-
ber of source classification categories
(SCCs). Each SCC represents a process
or function that is logically associated
with a point source of air pollution
within a given source category. The
objective of this effort was to estimate
VOC emission factors for categories
where substantial amounts of VOC
emissions would be expected. In addi-
tion to emission factors previously re-
ported, this report includes emission
factor estimates developed from a
variety of readily available information.
Data gathered during numerous stan-
dards-setting activities as well as data
provided from state emissions inventory
data bases were used to calculate the
new emission factor estimates. The
major emphasis of this effort was on
organic chemical manufacturing pro-
cesses and storage of petroleum pro-
ducts and organic chemicals.
This Project Summary was devel-
oped by EPA's Air and Energy Engi-
neering Research Laboratory. Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
As part of the NAPAP, EPA's Air and
Energy Engineering Research Laboratory
(AEERL) updated the October 1985 NEDS
Source Classification Codes and Emission
Factor Listing that was prepared by EPA's
Office of Air Quality Planning and Stan-
dards (OAQPS). VOC emission factor
estimates were generated for SCCs where
substantial amounts of VOC emissions
would be expected. The major emphasis
of this effort was on organic chemical
manufacturing process and storage of
petroleum products and organic
chemicals.
A review of OAQPS's 1985 NEDS docu-
ment showed that VOC emission factors
were needed for about 1,881 of the 3,112
SCCs in the listing. Of the 1,881 SCCs,
32% (605) were in the chemical manu-
facturing category alone. As a result of
the current effort, VOC emission factor
estimates were developed for 37% (700)
of the SCCs for which VOC emission
factors were previously unavailable.
Considering the complete listing, emission
factor estimates have been provided
through this effort for about 22% of all
SCCs, leaving about 38% without VOC
factors. While relatively large in number,
the 1,881 SCCs still lacking VOC emission
factor estimates are not major VOC emit-
ters. Table 1 summarizes the VOC emis-
sion factor development for the SCC
listing in 1985 NEDS document with
special focus on chemical manufacturing,
petroleum product storage, and organic
chemical storage.
The SCCs and emission factors that
are reported in OAQPS's 1985 NEDS
report resulted from updating all emission
factor changes through AP-42, Fourth
Edition. The 1985 NEDS report also con-
tains a number of new SCCs and changes
to existing SCCs that have been previously
listed.
In the current work by AEERL, the
primary objective was to provide VOC
emission factors for SCCs that had no
current listing of VOC emission factors.
The major effort was on SCCs with in-
formation that was readily available and
that would represent a significant quantity
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TABLE 1. SUMMARY OF VOC EMISSION FACTOR DEVELOPMENT
Category
Chemical
manufacturing3
Volatile organic
liquid storage11
Other
Total0
Total number
of SCCs
contained in
this category
691
433
1,988
3,112
Total number of
SCCs previously
with VOC
emission factors
86
76
1,069
1,231
Total number
of SCCs for
which VOC
emission factors
were developed
351
191
1S8
700
SCCs with
emission
factors, %
63
62
62
62
"Includes organic and inorganic chemical manufacturing processes.
b Fixed- and floating-roof storage tanks.
cOAQPS's 1985 NEDS document contains 3,112 SCCs of which 1,881 were previously
without VOC emission factors. VOC emission factors have now been developed for
700 of these SCCs. Many of the remaining categories are not major VOC emitters.
of VOC emissions to the atmosphere. The
new emission factors resulting from this
current work are not of the same quality
as emission factors tabulated in AP-42.
They were generated from sparse data
on units in the synthetic organic chemical
manufacturing industry (SOCMI) and from
emission factor estimates provided by
individual air quality districts within
states. In terms of the AP-42 ratings, the
estimates provided from this effort would
be considered of "E" quality.
A survey of the SCC and emission
factor listing given in OAQPS's 1985
NEDS document found that little data
were presented for organic chemical
manufacturing and storage of petroleum
products and organic chemicals. These
SCCs, therefore, were targeted as the
highest priority in evaluating new emis-
sion factors. Lower priority was assigned
to categories where little or no VOC
emissions were expected; e.g., inorganic
chemical manufacturing and smelting/
metal producing operations.
Chemical Manufacturing
Approximately 105 chemical manu-
facturing processes are given in the 691
SCC listings for the chemical industry.
For each process, individual unit opera-
tions are identified by individual SCCs
as having the potential to emit VOC
directly to the atmosphere. Approxi-
mately 57% of these chemical manufac-
turing processes comprising 605 SCCs
required emission factor estimates. A
total of 351 new emission factor esti-
mates were generated, with most
focused on air oxidation processes, plas-
tics manufacturing, and solvents
operations.
The new emission factors provided in
the report were generated from data
gathered during numerous standards-
setting activities and from data provided
from State emissions inventory data
bases. Dockets for new source per-
formance standards (NSPS) for fugitive
emissions, air oxidation processes, dis-
tillation operations, and reactor pro-
cesses within SOCMI were valuable
sources of VOC emissions data. These
dockets contain background information,
reference material, and industry re-
sponses to Clean Air Act Section 114
letters pertaining to the development of
the NSPS. In addition, two industry-
wide studies conducted in the 1970s
were reviewed to gather additional VOC
emissions data where information was
not available from the standards devel-
opment files. Even though this informa-
tion may be incomplete in terms of all
SCC listings, many of chemical manu-
facturing processes were provided with
some emission factor estimates. Suf-
ficient industry information was available
from these studies to calculate VOC
emission factor estimates for about 46%
of the 105 chemical. manufacturing
processes in OAQPS's 1985 NEDS docu-
ment. A number of source-specific
documents were used to supplement
the information gathered for VOC emis-
sion factors, including Background In-
formation Documents (BIDs), Source
Assessments, and chemical-specific
emission source survey documents.
Finally, six states (California, Texas,
Louisiana, Illinois, New Jersey, and West
Virginia) were contacted to gather in-
formation on VOC emissions. Since a
large portion of the organic chemical
manufacturing industry is located in
these states, they potentially have the
highest rate of process-related VOC
emissions. Most states contacted did
not have emissions data in a readily
available form (either not in computer
files, in confidential files, or unverified).
However, some current emission factor
data were made available for inclusion
in this report.
Volatile Organic Liquids Storage
Storage of petroleum products and
organic chemicals was the second area
of special interest for developing emis-
sion factor estimates. A total of 191 new
emission factors were estimated for
storage of petroleum products and or-
ganic liquids. Of this total, 88% were for
emissions from fixed- and floating-roof
tanks containing organic liquids.
Equations for estimating VOC losses
from storage tanks have been recently
revised by the American Petroleum
Institute (API). These revised equations
are included in the latest edition of Sec-
tion 4-3 of AP-42 (September 1985).
Tank dimensional data for model tanks
and assumptions on average atmospheric
conditions were repeated from AP-42,
Third Edition. Physical properties of
organic compounds were extracted from
published chemical abstracts. Using the
revised equations, breathing loss and
working loss emission factor estimates
were calculated for both fixed- and
floating-roof tanks for 89 chemicals.
Emissions data from state emission in-
ventory files were also used to complete
emission factor estimates for storage
losses. New VOC emission factor esti-
mates have been added for about 44%
of the SCCs concerning storage of petro-
leum products and organic chemicals.
Other Categories
Even though this effort focused on the
chemical industry and storage of volatile
organic liquids, emission factor estimates
were provided for 158 SCCs outside of
these two areas. Put into perspective,
estimates were generated for about 17%
of all other categories previously without
emission factors. The estimates provided
were based on readily available EPA
literature on vegetable oil processing,
plastics products, fiberglass reinforced
products, and metals-oriented opera-
tions, the last covering foundries and
smelters (copper, lead, zinc). In many
cases, emission factor estimates for
smelting operations have been listed as
negligible with emissions resulting from
uncombusted fuel. Similarly, VOC emis-
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sions from process heaters in various
industry groups have been tabulated as
negligible.
Recommendations
Recommendations for further study to
develop new VOC emission factors and
refine existing emission factors are
included in the report. Proposed activities
for further study include visiting states
where emissions inventory data are
available and conducting a more in-
depth literature search for quantitative
data on source categories where VOC
emissions are considered small. Addi-
tional computational techniques can also
be applied to estimate emission factors
for storage of organic chemicals and
petroleum products.
J. Stelling, M. Bloomhardt, and I. McKenzie are with Radian Corporation,
Research Triangle Park. NC 27709.
J. David Mobley is the EPA Project Officer {see below).
The complete report, entitled "VOC Emission Factors for NAPAP Emission
Inventory," (Order No. PB 87-141 040/AS; Cost: $18.95, subject to change)
will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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