United States
Environmental Protection
Agency j
Office of Air Quality January
Planning and Standards 1981
Research Triangle Park, NC 27711
National Emission Standards for Hazardous Air Pollutants
Benzene Emissions from
Ethylbenzene/Styrene Plants
Proposed Regulation
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Benzene Emissions from
Ethylbenzene/Styrene Plants
Proposed Regulation
Graphic Arts and Text Preparation:
Northrop Services, Inc.
Research Triangle Park, NC 27709
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National
Emission Standards
for Hazardous
Air Pollutants
The Clean Air Act as amended in 1977 re-
quires a comprehensive national program
for reducing air pollution and improving air
quality. Section 112 of the Act authorizes
EPA to establish National Emission Stan-
dards for Hazardous Air Pollutants
(NESHAPS). Hazardous air pollutants
being considered for NESHAPS regulation
are defined by the Act as substances (1) to
which no ambient air quality standard is
applicable and (2) that may reasonably be
anticipated to result in an increase in mor-
tality, in serious irreversible illnesses, or in
incapacitating, reversible disorders. Each
standard is to be set at a level that pro-
vides, in the judgment of the Adminis-
trator, an ample margin of safety to pro-
tect the public health. NESHAPS apply to
new sources immediately upon promul-
gation and to existing sources within 90
days of the effective date, though under
special circumstances existing sources may
be given up to two years to comply. Each
state may develop and submit to EPA a
procedure for implementing and enforcing
NESHAPS for stationary sources located
within the state, which EPA will review for
efficacy. EPA is now proposing a NESHAPS
for benzene emissions from the process
vents of ethylbenzene/styrene plants.'This
standard was developed in accordance with
EPA's proposed "Policy and Procedures for
Identifying, Assessing, and Regulating Air-
borne Substances Posing a Risk of Cancer."
This policy was proposed on October 10,
1979.
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Benzene
Benzene was listed
as a hazardous air
pollutant by EPA on
JuneS, 1977. Stu-
dies of industrially-
exposed workers
have shown that ben-
zene is causally rela-
ted to the induction
of a number of blood disorders. Among
these diseases are leukemia (a cancer of the
hematopoietic, or blood-forming, system),
various cytopenias (decreased levels of
formed elements in the circulating blood,
such as red cells, white cells and platelets),
aplastic anemia (a nonfunctioning bone
marrow), and potentially-inheritable chro-
mosomal aberrations. The severity of hema-
topoietic diseases ranges from mild and
episodic to chronic and fatal.
The proposed NESHAPS would reduce the
estimated maximum lifetime risk of leu-
kemia to individuals exposed to benzene
emissions from ethylbenzene/styrene pro-
cess vents from a range of 6.2 x 10~4 to 4.4
x 10'3 to a range of 1.7 x 10'6 to 1.2 x
10~5. The estimated nationwide incidence
of leukemia deaths attributable to exposure
to benzene emissions from ethylbenzene/
styrene process vents (within 20 kilometers
(12 miles) of ethylbenzene/styrene plants)
would be reduced from a range of 0.03 to
0.2 to a range of 1.3 x 10'4 to 9.2 x 10'4
per year.
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Ethylbenzene/
Styrene
Plants
Benzene is used in
the production of
ethylbenzene, and
99 percent of the
ethylbenzene manu-
factured is used to
produce styrene.
Ethylbenzene and
styrene are considered jointly for regu lation
because the processing plants are located
together and are frequently integrated.
(Styrene is produced only from ethylben-
zene.) Polymer manufacture consumes
virtually all produced styrene.
Stationary sources account for 20 percent
of the total benzene emissions released in
the United States, with the remaining 80
percent due to mobile sources. Ethylben-
zene/styrene plants are the second largest
single source of benzene emissions in the
chemical industry, discharging 17 percent
of all benzene emitted from chemical
manufacturing. Regulations to control the
industry's largest single source, maleic an-
hydride plants, have been proposed (see
Federal Register 18 April 1980).
The benzene emissions specifically affected
by the proposed regulation would be those
released from the vents of any of the fol-
lowing equipment pieces: the alkylation
reactor section, atmospheric and pressure
columns, the hydrogen separation system,
or vacuum-producing devices. The rule-
making would apply to the 13 existing
plants producing ethylbenzene and/or
styrene and any new plants construc-
ted. Separate standards are being developed
which will cover fugitive and storage sources
of benzene emissions, including ethylben-
zene/styrene sources.
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The Proposed
Standard for
Limiting
Emissions
The proposed regu-
lation would apply
to all process vent
streams emitted at
existing and new
ethylbenzene/
styrene plants in the
production of ethyl-
benzene from ben-
zene alkylation, and the production of
styrene from ethylbenzene dehydrogen-
ation and from ethylbenzene hydroper-
oxidation. These process vent streams are
defined as any continuous benzene-contain-
ing gases released or having the potential
of being released to the atmosphere from
the alkylation reactor section, atmospheric
and pressure columns, the hydrogen sep-
aration system, or vacuum-producing de-
vices. The regulation would result in 99
percent control of emissions from such con-
tinuous process vents, reducing the total
continuous process benzene emissions from
the industry to 70 megagrams (76 tons)
per year. The permissible limit of benzene
discharges into the atmosphere would be 5
parts per million by volume on a dry basis
corrected to three percent oxygen.
The proposed standard would not allow
emissions in excess of the numerical
emission limit except when a sudden and
unavoidable failure of air pollution control
or process equipment occurs, or during
plant startup and shutdown. These emis-
sions would have to be combusted with one
or more smokeless flares (or an equivalent
means of control). The proposed standard
would reduce estimated nationwide emis-
sions due to start up, shutdown and control
and process equipment failures from 133
megagrams (146 tons) per year to 21
megagrams (23 tons) per year. Owners
and operators of all ethylbenzene/styrene
plants would also be required to install
continuous monitoring systems and report
any occurrences of emissions in excess of
the numerical limit, as indicated by changes
in boiler operation parameters such as
temperature, flue gas oxygen content
and gas stream flow.
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Achieving and
Maintaining
the Standard
The proposed stan-
dard is based on the
best available tech-
nology for reducing
benzene emissions,
{ considering environ-
V ) mental, economic
^—->^^ -r—\ and energy impacts.
X/ ^ It can be achieved
through add-on controls, such as boilers
and process heaters, which are currently
used at all ethylbenzene/styrene plants as
part of the production process. These con-
trols are not specifically required by the
proposed standard, but have been proven as
viable means to curb emissions. These con-
trols would involve routing the vacuum col-
umn vents, the atmospheric and pressure
column vents, the alkylation reactor vents,
and the hydrogen separation vent to an
existing boiler or process heater to attain a
99-percent emission reduction.
Continuous monitoring systems that would
monitor certain process parameters would
be used to indicate occurrences of emissions
in excess of the numerical emission limit.
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Impacts
Environmental: Na-
tionwide annual re-
ductions of benzene
emissions from eth-
ylbenzene/styrene
plants, operating at
full capacity, would
be 2,009 megagrams
per year (from 2,100
to 91 megagrams) or 2,210 tons (from
2,310 to 100tons). These reductions would
be achieved with no significant increase in
waste water or effluent discharge by ethyl-
benzene/styrene plants. Noise and thermal
radiation associated with the use of flares
are negligible.
Energy: Due to recovered heat energy, a
99 percent reduction in continuous benzene
emissions would result in a small total na-
tionwide energy savings, equivalent to ap-
proximately 0.1 percent of the current na-
tionwide ethylbenzene/styrene fuel re-
quirements.
Economic/Industrial: Capital costs for
achieving the 99-percent level of control
range from zero to $686,000 per plant, ac-
counting for additional piping and controls
for existing burners. Total annualized costs,
including operating and maintenance costs,
annualized capital costs, and recovered ma-
terial and fuel credits, would range from a
cost of $68,750 to a savings of $140,000
per plant. The potential maximum styrene
price increase would be as much as 0..27
percent.
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Public
Participation
A public hearing on
the proposed regu-
lation is scheduled
for February 5,1981
beginning at 9a.m.
at EPA Administra-
tion Building Audi-
torium, Research
Triangle Park, NC
27711. Individuals who wish to present
additional data, views, or other comments
concerning this NESHAPS regulation are
invited to participate. If you wish to speak
atthe meeting, contact Ms. Naomi Durkee,
Emission Standards and Engineering Divi-
sion (MD-13), U.S. Environmental Protec-
tion Agency, Research Triangle Park, North
Carolina 27711, telephone 919/541-5331
by January 29, 1981.
Written comments will be accepted on or
before March 7, 1981 and should be
submitted in duplicate and addressed to
Central Docket Section (A-130), Atten-
tion: Docket Number A-79-49 U.S. Envi-
ronmental Protection Agency, West Tower
Lobby, Gallery 1, Waterside Mall, 401 M
Street, SW, Washington, DC 20460. The
docket; contains all information considered
by EPA during the development of this
standard and is open for inspection. The
background document for the proposed
standard may be obtained from the EPA
Library (MD-35), Research Triangle Park,
North Carolina 27711, telephone 919/541
-2777. Refer to: Benzene Emissions from
the Ethylbenzene/ Styrene Industry—Back-
ground Information Document for Pro-
posed Standards (EPA 450/3-79-035a).
Supporting documents on benzene health
effects may also be obtained: Assessment of
Health Effects of Benzene Germane to
Low-Level Exposures (EPA 600/1-78-061),
Assessment of Human Exposures to Atmo-
spheric Benzene (EPA450/3-78-031), and
Carcinogen Assessment Group's Report on
Population Risk to Ambient Benzene
Exposures (EPA 450/5-80004).
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Status of The proposed standard was published in scheduled for February 5, 1981, and the
Regulation the Federal Register (FR 45 83448) on final regulation is scheduled for publication
December 18 , 1980. A public hearing is in January, 1982.
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