United States EPA-600/R-96-136
Environmental Protection
A9encv November 1996
&EPA Research and
Development
ADDENDUM TO
ASSESSMENT OF STYRENE EMISSION
CONTROLS FOR FRP/C AND
BOAT BUILDING INDUSTRIES
Prepared for
Office of Air Quality Planning and Standards
Prepared by
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
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FOREWORD
The U. S. Environmental Protection Agency is charged by Congress with pro-
tecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions lead-
ing to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA's research
program is providing data and technical support for solving environmental pro-
blems today and building a science knowledge base necessary to manage our eco-
logical resources wisely, understand how pollutants affect our health, and pre-
vent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for
investigation of technological and management approaches for reducing risks
from threats to human health and the environment. The focus of the Laboratory's
research program is on methods for the prevention and control of pollution to air,
land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated sites and groundwater; and prevention and
control of indoor air pollution. The goal of this research effort is to catalyze
development and implementation of innovative, cost-effective environmental
technologies; develop scientific and engineering information needed by EPA to
support regulatory and policy decisions; and provide technical support and infor-
mation transfer to ensure effective implementation of environmental regulations
and strategies.
This publication has been produced as part of the Laboratory's strategic long-
term research plan. It is published and made available by EPA's Office of Re-
search and Development to assist the user community and to link researchers
with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
EPA REVIEW NOTICE
This report has been peer and administratively reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Information
Service, Springfield, Virginia 22161.
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EPA-600/R-96-136
November 1996
Addendum to Assessment of Styrene
Emission Controls for FRP/C and
Boat Building Industries
Final Report
by:
Emery J. Kong, Mark A. Bahner, and Sonji L. Turner
Research Triangle Institute
P.O.Box 12194
Research Triangle Park, NC 27709
EPA Contract 68-D1-0118, W.A. 192
EPA Project Officer: Norman Kaplan
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Prepared for
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
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Abstract
This report is an addendum to a 1996 EPA report entitled Assessment ofStyrene Emission
Controls for FRP/C and Boat Building Industries. This addendum presents additional evaluation
of the biological treatment of styrene emissions, Dow Chemical Company's SORBATHENE®
solvent vapor recovery system, Occupational Safety and Health Administration regulations and
other policies that affect the fiber reinforced plastics/composites (FRP/C) and boat building
industries, and secondary pollution and natural gas usage resulting from various emission control
options.
This study concludes that:
• Based on available results from bench- and pilot-scale studies and full-size
operation, biofiltration or a bioscrubber could be a viable control option for
treatment of styrene emissions.
• Dow Chemical's SORBATHENE® vapor recovery system was developed for
high-concentration, low-flow exhaust from storage vents and would not be
economically feasible for low-concentration, high-volume flow typically found in
the most prominent processing techniques in the FRP/C and boat building
industries.
• Employers should comply with current or future permissible exposure limits
(PELs) for styrene using feasible engineering controls and should provide
respiratory protection to employees when worker exposure cannot meet PELs
after feasible engineering controls have been implemented. It is also an industrial
practice for employers to provide additional respiratory protection to the
employees even though the PELs are met.
• Direct thermal oxidation or catalytic oxidation would be less economical than
preconcentration/oxidation technologies for low-concentration, high-volume
emissions typically found in the industries. Secondary pollution and natural gas
usage could be reduced significantly when using preconcentration technologies
followed by catalytic oxidation.
11
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Contents
Abstract ii
Figures v
Tables v
Acronyms and Abbreviations vi
Conversion Table viii
Chapter 1 Introduction 1
References 1
Chapter 2 Biological Treatment 2
2.1 System Information Requested 2
2.2 Descriptions of Biological Treatment Systems 2
References 8
Chapter 3 Novel Styrene Emission Control Technology 9
3.1 Dow Chemical SORB ATHENE® Solvent Vapor Recovery Unit 9
References 11
Chapter 4 OSHA Regulations and Policies Affecting Worker Exposures in the FRP/C and
Boat Building Industries 12
4.1 Summary and Implication of OSHA Regulations 12
4.2 De Minimis Violations 13
4.3 Local Air Flow Management and Spray Booth Modifications 14
References 15
Chapter 5 Assumptions in the Society of Plastics Industry/Composites Institute's (SPI/CI)
Study on Noneconomic Impacts of Incineration Controls 17
5.1 Use of Thermal Oxidizer 17
5.2 Control Device Inlet Concentration of 20 ppm 17
5.2.1 Economic Incentives for Maximizing Inlet Concentrations 19
5.2.2 Exhaust Concentrations at Existing Plants 19
5.2.3 Recent and Potential Future Changes in Allowable Exposures to Styrene21
5.2.4 Existing Relationships Between Worker Exposure and Exhaust
Concentration 21
5.2.5 Potential Methods to Increase Concentration to Downstream Controls . 21
5.2.6 Conclusions on Assumption of Control Device Inlet Concentration of 20
ppm 23
References 24
Chapter 6 RTI Analysis of Noneconomic Impacts of Controls 25
6.1 Normalized Curves for Natural Gas Usage and Secondary Pollutant Emissions 25
6.1.1 Natural Gas Usage 25
iii
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Contents (continued)
6.1.2 Carbon Dioxide Emissions 27
6.1.3 Nitrogen Oxide Emissions 27
6.2 Calculations for Specific Plant 29
6.2.1 Natural Gas Usage 31
6.2.2 Carbon Dioxide Emissions 31
6.2.3 Nitrogen Oxide Emissions 34
6.2.4 Radon Emissions 34
6.3 Conclusions 37
References 37
APPENDIXES
A Comments on Individual Statements in the SPI/CI Study 39
B Revision of the Styrene Control Cost Spreadsheet Model and Cost Figures 43
IV
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Figures
No. Page
2-1 VVK Weege GmbH bioscrubber system 7
3-1 Process diagram of a SORB ATHENE solvent vapor recovery unit 10
5-1 Cost curves for a large plant (400 tons per year inlet) 18
5-2 Typical open molding operation in a spray booth 22
6-1 Normalized natural gas usage for various control options and for sensible heating
of exhaust stream 26
6-2 Normalized additional carbon dioxide generated by natural gas combustion for
various control options 28
6-3 Normalized NOX emissions for various control options 30
6-4 Natural gas usage for various control options and for sensible heating at a typical plant 32
6-5 Carbon dioxide emissions for various control options at a typical plant 33
6-6 Nox emissions for various control options at a typical plant 35
6-7 Radon emissions due to natural gas combustion for various control options at a typical
plant 36
Tables
No. Page
2-1 Properties for Styrene Abatement Biosystems 4
5-1 Styrene Exhaust Concentrations at Existing Open Molding Plants with Resin/Gel Coat
Usage Greater than 1,000 ton/yr 20
5-2 Comparison of average styrene exhaust concentration (290 ppm) with worker exposure
levels at Lasco Bathware, South Boston, VA 23
6-1 Characteristics for Specific Plant (Universal Rundle, in Ottumwa, Iowa) 31
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Acronyms and Abbreviations
ACGIH American Council of Government Industrial Hygienists
BACT best available control technology
Btu British thermal unit
CAAA Clean Air Act Amendments of 1990
CE capital equipment (cost)
CEFIC Unsaturated Polyesters Sector Group of European Chemical Industry Council
CFCs chlorofluorocarbons
CO carbon monoxide
CO2 carbon dioxide
EC equipment cost
EC&C Environmental C&C, Inc.
EPA Environmental Protection Agency
FID flame ionization detector
FRP/C fiber-reinforced plastics/composites
ft feet
ft/min feet per minute
GPRMC European Organization of Reinforced Plastics/Composite Materials
HAP hazardous air pollutants
H.R. heat recovery
kW kilowatt
kWh kilowatt-hour
Ib pound
Ib/h pounds per hour
LEL lower explosive limit
MACT maximum achievable control technology
MIAB Molnbacka Industri, AB
NFPA National Fire Protection Association
NOX nitrogen oxides
OAQPS Office of Air Quality Planning and Standards
OSHA Occupational Safety and Health Administration
PADRE Polymer Adsorption and Removal
PC personal computer
PEC purchased equipment cost
PEL permissible exposure limits
ppm parts per million (by volume)
PSA pressure swing adsorption
psig pounds per square inch, gage
REECO Regenerative Environmental Equipment Co., Inc.
RFC reinforced plastic composites
RTI Research Triangle Institute
SIC Standard Industrial Classification
SMC sheet molding compound
VI
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SP1/CI Society of the Plastics Industry/Composites Institute
STC Southeastern Technology Center
STEL short-term exposure limit
TCI total capital investment
TDC total direct cost
TLV threshold limit value
ton/yr tons per year
TRI Toxics Release Inventory
TVA Tennessee Valley Authority
TWA time-weighted average
VOC volatile organic compound
yr year
°C degrees Celsius
°F degrees Fahrenheit
VII
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Conversion Table
The U.S. Environmental Protection Agency policy is to express all measurements in Agency
documents in metric units. In this report, however, to conform to industrial convention, English
units are used. Conversion factors from English to metric units are given below.
English Unit
Btu
op
ft
ft2
ft3
ft3/min (cfm)
gal/min
inch
in. H2O
Ib
psia
ton
Multiply by
1.055xl03
(°F-32)/1.8
0.3048
0.0929
0.0283
0.028314
3.79
2.54
1.87
0.454
6.895
0.907
To Obtain
joule
°C
m
m2
m3
m3/min
1/min
cm
mmHg
kg
kilopascal
Mg
Vlll
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Chapter 1
Introduction
The 199Q Clean Air Act Amendments (CAAA) mandate the development and
promulgation of standards for hazardous air pollutants (HAP) emitted from a multitude of source
categories by the year 2000. Styrene is listed as a HAP in the CAAA, and it is known to be
emitted from the fiberglass-reinforced plastics/composites (FRP/C) and boat building industries.
An earlier study (Kong et al., 1996) assessed the available control technologies, their efficiencies,
performance, and cost. That study also reviewed and summarized Occupational Safety and
Health Administration (OSHA) regulations governing the worker exposure issues, and presented
the air flow management practices that could achieve cost-effective control of styrene emissions.
This report presents additional evaluation of the biological treatment of styrene
emissions, Dow Chemical Company's SORBATHENE® solvent vapor recovery system, OSHA
regulations and other policies that affect the FRP/C and boat building industries, and secondary
pollution and natural gas usage resulting from various emission control options.
This study concludes that:
1. Based on available results from bench- and pilot-scale studies and full-size operation,
biofiltration or a bioscrubber could be a viable control option for treatment of styrene emissions.
2. Dow Chemical's SORBATHENE® vapor recovery system was developed for high-
concentration, low-flow exhaust from storage vents and would not be economically feasible for
low concentration, high-volume flow typically found in the most prominent processing
techniques in the FRP/C and boat building industries.
3. The employers should comply with current or future PELs for styrene using feasible
engineering controls and should provide respiratory protection to the employees when worker
exposure can not meet PELs after feasible engineering controls have been implemented. It is
also an industrial practice for employers to provide additional respiratory protection to the
employees even though the PELs are met.
4. Direct thermal oxidation or catalytic oxidation would be less economical than
preconcentration/oxidation technologies for low-concentration, high-volume emissions typically
found in the industries. Secondary pollution and natural gas usage could be reduced significantly
when using preconcentration technologies followed by catalytic oxidation.
References
Kong, E.J., M.A. Banner, and S.L. Turner. September 1996. Assessment of Styrene Emission
Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640),
Research Triangle Park, NC.
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Chapter 2
Biological Treatment
Biological treatment uses microorganisms in a medium, usually a biofilter or bioscrubber,
to destroy organic compound emissions in an air stream. Air emissions containing biodegradable
constituents pass through a biologically active medium. The microorganisms degrade the
organic constituents in the air stream to essentially carbon dioxide and water. Biofiltration has
been used for many years in Europe, Japan, and the United States for odor control, but the use of
biofiltration to degrade more complex air emissions from chemical plants has occurred only
within the last few years. Descriptions of biofiltration and biotrickling filter systems are
presented in an EPA report (Kong et al., 1996). Biofiltration and biotrickling filter are similar in
principle, but different vendors use different designs and media. This addendum includes
another new biological treatment system which comprises a bioscrubber and a bioreactor. This
section presents the process descriptions and information for several biological treatment units
that have been tested or applied for styrene emissions.
2.1 System Information Requested
The Research Triangle Institute (RTI) contacted seven researchers and suppliers to obtain
available information on their various existing and proposed biological treatment systems. The
request included but was not limited to information on the following:
• flow rates * • composition of the bio-medium
• emission source • incubation period of the bio-medium
• concentration • size of the biofilter
• capture efficiency. • pressure drop
• control efficiency • acclimation period
• time of operation (hours/day, days/week) • performance during startup
• number of persons required for operation • performance after periods of shutdown
• frequency of regeneration • capital and operating costs
Five facilities responded by the requested deadline to provide information for this report:
Envirogen, Tennessee Valley Authority (TVA), VVK Weege GmbH, Southeastern Technology
Center (STC), and EnvirOzone, Inc.
2.2 Descriptions of Biological Treatment Systems
Envirogen. Envirogen provided information for two units, a pilot-scale biofilter and a proposed
full-scale biotrickling filter. The pilot-scale biofilter was tested on air discharged from a
fiberglass spray booth operation. The full-scale biotrickling filter was designed to control styrene
emissions generated by a sequence batch reactor in a chemical company's wastewater treatment
facility; however, the system was never put into service. Currently, CVT Bioway is conducting a
field pilot study with TNO in Europe. This work is confidential and remains unavailable to
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Envirogen. (Envirogen and a Dutch company have a joint venture company called CVT
America. CVT America has potential access to license TNO's technology through a sister
company called CVT Bioway. CVT Bioway is a separate company from CVT America.) As
data and information from this field study become available to them, Envirogen will update RTI.
Information on the Envirogen biotreatment system is presented in an EPA report (Kong et al.,
1996). Properties for their pilot-scale system and design specifications for their full-scale system
are listed in Table 2-1.
TVA. In 1989, 1.04 x 106 kg (1,144 tons) of styrene was emitted by manufacturing industries in
the Tennessee Valley making styrene the second largest Toxic Release Inventory (TRI) classified
toxic chemical released in the region (Lackey et al., 1994). Laura Lackey with TVA conducted
bench-scale and pilot-scale studies to eliminate styrene emissions from the air streams of an
industrial partner and other varied industrial applications. For bench-scale biofilter experiments,
a parallel series of three bench-scale 2.8-L biofilters was constructed. All three biofilters were
packed with a 1:1 (v/v) mixture of pine bark and composted chicken litter. A stainless steel
screen supported the packing material creating a free space at the bottom of each biofilter. A
controlled feed of styrene-contaminated gas entered the free space, and purified air exited the top.
For the bench-scale experiments, biofilters were operated continuously for a 7-month period.
Biofilter 1, the Control, was autoclaved and served as a sterile control. Biofilter 2 was
inoculated with a styrene-degrading consortium of organisms, and Biofilter 3 used only naturally
occurring microorganisms. Inlet styrene concentrations ranged from 50 to 4,000 ppmv and the
empty bed contact time varied between 1 and 8 minutes. During days 29 to 36, the humidity of
the incoming air stream was inadvertently dropped below the normal 99 percent to below 50
percent relative humidity. This drop caused the removal efficiency of Biofilter 2 to decrease to
60 percent. After the humidity was returned to normal, the performance of Biofilter 2 quickly
improved and removal efficiency increased to greater than 99 percent. This problem did not
occur with Biofilter 3. After the initial acclimation period, the performances of Biofilter 2 and
Biofilter 3 were similar, greater than 99 percent (L.W. Lackey, TVA, personal communication,
Sept. 4, 1996).
The pilot-scale biofilter that was installed at a boat building manufacturing site was 0.8
meters in diameter with a total packing volume of 1.26 m3 (Holt and Lackey, 1995). It was also
filled with a 1:1 (v/v) mixture of pine bark and composted chicken litter. The pilot-scale biofilter
was monitored for 3 months. During normal manufacturing, the spray booth was operated for
three shifts each day (20 h/d). Following the first week of operation and microbial acclimation,
the manufacturing facility shut down for 1 week. During the shutdown, the biofilter continued to
operate, and the system was maintained under aerobic conditions by blowing an uncontaminated
air stream through the biofilter. Some styrene breakthrough was noted during the first shift after
the week of downtime. However, no styrene was detected in the biofilter effluent for the next 2
months when the empty bed contact time was maintained at a constant rate. Additional
information about the properties for both systems is listed in Table 2-1. Lackey plans to design a
demonstration-scale 340-m3/min (12,000-ft3/min) biofiltration system based on the results of the
two studies. However, a decision to construct the demonstration-scale system is currently on
hold until there are regulatory requirements to build it.
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Table 2-1. Properties for Styrene Abatement Biosystems
Bioreactor
Parameters
Unit type
Reactor type
Reactor size
Emissions source
Other pollutant(s)
Flow rate
Styrene concentrations
Control efficiency
Time of operation
Persons needed for
operation
Media replacement
Companies
ENVIROGEN
Pilot
Biofilter
0.85 m3
(30 ft3) medium
Fiberglass spray
booth operation
Full-scale"
Biofilter
0.28m3 (10 ft3)
Wastewater
treatment facility
NA
7.08 x 10° to
5.66xl03m3/s
(15tol20ft3/min)
NA
>95% @ 30+ sec
85% to 95% @15
sec
16h/d, 5d/wk,
4 months
0.6608 mVs
(I,400ft3/min)
NA
90% removal
24 h/day
1
5 to 7 years
Life of system
TVA
Bench"
Pilot
Biofilter
2.8 x 10'3 m3
(0.099 ft3)
Controlled
contaminated feed
Acetone
NA
50 to 4,000 ppmv
(inlet)
>99% removal
(Biofilter 2)
>99% removal
(Biofilter 3)
7 months
1.26m3
(44.5 ft3)
medium
Boat
manufacturer
MEK
Acetone
2.83 x 103to
2.12 xlO'3
(6 to 45 ftVmin)
0 to 400 ppmv
(inlet)
>98% removal
13 months
None
NA
VVK Weege
Full-scale
Bioscrubber
Designed for
treatment requiredc
Automotive parts
production
NAd
20,000 mVh
(Il,774ft3/min)
50to60ppm
(inlet)
5 ppm (outlet)
- 90% removal
8 h/d, 5 d/wk,
10.5 mo/yr
None
Life of system
STC
Pilot
Biofilter
21.62m3
(763.4 ft3)
FRP facility
MEK
0.472 to 0.944 mVs
(1,000 to 2,000
ftVmin)
30 ppm (inlet)
0.3 ppm (outlet)
99%
24 h/day
None
4 to 7 years
(continued)
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Table 2-1. Continued
Bioreactor
Parameters
Unit type
Media composition
Acclimation period
Pressure drop
Startup performance
Shutdown
recovery
Capital cost
Operating cost
Companies
ENVIROGEN
Pilot
Proprietary
engineered organic
based material
~ 1 week
1 in. to 2 in. H2O
@ start-up
8 in. H2O design
75 % @ 60 sec
5to8h
(weekend
shutdown)
NA
NA
Full-scale2
Synthetic packing
1 to 2 weeks
(expected)
< 1 in. H2O
(expected)
NA
NA
Available upon
request
Available upon
request
TVA
Bench"
Pilot
1 : 1 (v/v) pine bark and composted
chicken litter
- 5 days (Biofilter 2)
- 55 days (Biofilter
3)
0.003 in. H2O (max)
NA •
0.75 in. H2O
(max)
NA
NA
NA
NA
VVK Weege
Full-scale
Proprietary
NA
NA
NA
'/z to 1 h
(after shut-down)
$450,000 to
$700,000
$25/day to
$30/day
STC
Pilot
80% chicken
compost
20% GAC
2 to 3 weeks
20 to 30 in. H2O
30 to 70 %
variable
$140,000
(w/engineering)
$400/month
NA = not available.
a. Design parameters of this systems are listed. The system currently is not in use.
b. A parallel series of three bench-scale biofilters were used for this bench-scale test. Biofilter 1 was autoclaved and served as a sterile control. Biofilter 2 was
inoculated with a styrene-degrading consortium of organisms. Biofilter 3 utilized only naturally occurring microorganisms.
c. Each system is designed to handle specific waste streams. Normal height of filter material is a maximum of 1 to 1.25 m. For 100 to 150 m3 of emissions,
estimate approximately 1 m3 of filter material.
d. System can be engineered for specific waste streams of volatile organic compound (VOCs). A series of bioscrubbers can be designed for each individual unit
to treat a specific VOC.
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VVK Weege GmbH. VVK Weege GmbH, an engineering company in Wiesbaden, Germany,
developed a bioscrubber system that removes styrene and other volatile organic compounds
(VOCs) from industrial waste gases. The bioscrubber system employs a four-step process to treat
styrene and VOC emissions from industrial waste gas. As shown in Figure 2-1, industrial waste
gases enter a packed absorption tower where styrene is absorbed into the countercurrent flow of
the absorbent solution (i.e., water and clean effluent from the bioreactor). The absorption tower
consists of packing, a droplet separator, and a liquid distributor. After this step, clean air leaves
the tower, and the styrene-laden absorbent solution is pumped into a stirred bioreactor. In the
bioreactor, styrene is biologically degraded. After the degradation is complete, proprietary
additives are applied to maintain the bacteria population, and the clean effluent from the
bioreactor is pumped to the absorption tower for reuse. No sludge or solid waste is generated
from the bioscrubber process.
The bioscrubber system is equipped with sensors and measuring devices and a computer
to control the operations of the system. VVK Weege sells a service contract to maintain and
operate the system. The personal computer (PC) station is the heart of data acquisition for the
bioscrubber system. The PC station collects all data and controls various functions of the system,
such as refilling water to make up for evaporation loss, replenishing the additives, and
controlling the system. Through modern communication methods, these data are communicated
back to VVK Weege. This information transfer allows VVK Weege to continually monitor the
function of the system and to remotely adjust the system when necessary using a fax modem.
Two bioscrubber systems exist in Germany: one is a laboratory-scale facility, the other is
a commercial unit used by a German company using sheet molding compound (SMC) to
manufacture automotive parts. The commercial unit operated for one year but is no longer in
operation now. Rudi Weege, company president, provided RTI with an overview of the
commercial unit. Information for the commercial system is provided in Table 2-1.
The cost data in Table 2-1 for the VVK Weege system are taken from published literature
(Modern Plastics, 1996). The capital costs for a system handling 11,766 ftVmin are estimated to
be between $450,000 and $700,000. This can be compared to estimated equipment costs and
total capital investments of $301,000 and $619,000, respectively, from the biofiltration cost
spreadsheet developed in the original styrene controls assessment. Operating costs are given as
approximately $25 to $30 per day. This can be compared with an electrical cost estimate of
approximately $15 per day from the biofiltration cost spreadsheet (assuming electricity cost of
$0.06 per kWhr, operating 8 hours per day).
VVK Weege is in the process of establishing a North American subsidiary to introduce
and commercialize their technology to the FRP composite industry and other industries emitting
VOCs in North America. According to Weege, the system can be designed to treat various
VOCs, with each unit dedicated to treating a specific pollutant.
Southeastern Technology Center (STC). STC is a non-profit corporation whose mission is to
facilitate the transfer of commercially viable technologies from the government sector to the
business sector for the purpose of promoting economic development and creating jobs.
6
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Clean Air
Water
Stirrer
Aerator
Reactive
Additive
Data Acquisition
1
Flow of
Absorbent
Solution
Bioreactor
Absorption
Tower
Waste
Gas
Figure 2-1. VVK Weege GmbH bioscrubber system.
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Regina Porter at STC is conducting a pilot study for styrene removal from an FRP facility. Her
research is being conducted under a Department of Energy (DOE) contract. Delphinus
Engineering, Inc. and EnvirOzone, Inc., both in South Carolina, are subcontractors to STC and
are responsible for the design and operation of the pilot-scale unit. Delphinus and EnvirOzone
provided preliminary information for this report for a 21.62-m3 (764-ft3) pilot-scale unit that has
been designed to treat gaseous exhausts from an FRP facility. The flow rates of the exhaust
streams range from 0.472 to 0.944 m3/s (1,000 to 2,000 ftVmin). The biofilter media contains 10
tons (9,070 kg) of chicken compost (80 percent chicken manure and 20 percent granular
activated carbon) that requires a 2- to 3-week incubation period. Additional information for this
pilot unit can be found in Table 2-1 (A. Saha, Delphinus Engineering, personal communication,
Sept. 11, 1996).
References
German Firm Develops Styrene-Abatement System. Modern Plastics, p. 17, March 1996.
Holt, T., and L. Lackey. 1995. Control of gas contaminants in air streams through biofiltration.
Proceedings of 50th Purdue Industrial Waste Conference.
Kong, E.J., M.A. Banner, and S.L. Turner. September 1996. Assessment of Styrene Emission
Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640),
Research Triangle Park, NC.
Lackey, L. W., M.T. Holt, J.R. Gamble, and C.E. Breed. 1994. Biofilter Systems for the Control
of Gas Contamination in Air Streams. Paper presented at the Southern States Annual
Environmental Conference, October 20.
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Chapter 3
Novel Styrene Emission Control Technology
3.1 Dow Chemical SORBATHENE® Solvent Vapor Recovery Unit
The Dow Chemical Company developed the SORBATHENE® pressure swing adsorption
(PSA) process in the late 1980s to recover VOCs and other valuable chemical products from
storage, loading, and process vents. Since 1988, the Dow Chemical Company has installed 19
SORBATHENE® units to recover hydrocarbon, chlorofluorocarbons (CFCs), chlorinated
solvents, aromatics, and monomers. Dow Chemical has two SORBATHENE® units for recovery
of styrene vapors from storage vents. A SORBATHENE® unit can be designed to achieve 99.9%
VOC removal from vent streams ranging in flow rate from 20 to 3,000 ft3/min with feed
concentrations between 1,000 and 500,000 ppm (Collide et al., 1996). The chemical components
are recovered as a condensed liquid. Based on the evaluation of this technology and a follow-up
conversation with Larry Larrinaga (Radian International, personal communication, September 9,
1996), the SORBATHENE® technology would be expensive to treat the low-styrene
concentration (less than 200 ppm) at high flow rates (greater than 5,000 ftVmin) typically found
in the most prominent processing technologies (e.g., sprayup and hand layup in open molding
processes) in the FRP/C facilities.
Process Description. The SORBATHENE® process is typically applied to recover
organic vapors from process vents, storage tanks, and loading/unloading operations. The process
uses PSA and the heat generated during adsorption to desorb the VOCs collected on the
adsorbent. Adsorption is carried out at atmospheric pressure and the heat of adsorption is
retained in the adsorption bed, then the adsorbate is desorbed at a lower pressure (i.e., under
vacuum) using the retained heat. Optimal desorption pressures are selected between 50 and 300
mm Hg (1 and 5.8 psig). As shown in Figure 3-1, the adsorption and desorption steps are batch
processes that occur simultaneously in alternating twin beds to maintain steady state operation of
the unit. During the desorption step, a fraction of the clean gas leaving the adsorbing bed is used
as the backpurge gas for desorption. The concentrated stream of desorbed VOC is drawn through
a vacuum system then passes through a condenser where the VOC condenses and is removed as a
liquid. The cooling medium is selected based on the temperature required to condense the vapor.
Control valves switch the beds over short cycle times to avoid an excessive temperature rise
caused by the heat of adsorption. The SORBATHENE® unit is designed for the maximum
instantaneous feed concentration and flow rate that would be expected during operation of the
unit. The unit would not require adjustment as the inlet flow rate and concentration vary due to
tank filling operation.
Standard Operating Conditions. The process has been applied for vent streams ranging
from 20 to 3,000 ftVmin concentrations between 1,000 and 500,000 ppm. The adsorbent,
operating pressures and temperatures, and cycle time of the unit are determined in a pilot study
based on the characteristics of the VOC to be recovered. Each unit is tailored to the specific
VOC and the characteristics of the exhaust stream.
-------
> Clean Vent Stream
Describing Unit
4f
Adsorbing Unit
Feed Stream -r-C>—
: open valve
: closed valve
: adsorbing flow
: desorbing flow
Condenser
Separator
Recovered
Liquid
Figure 3-1. Process diagram of a SORBATHENE solvent vapor recovery unit.
10
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Control Efficiency. A SORBATHENE® unit has been tested for styrene vapor recovery
from storage vents and its recovery efficiency was 99.78 percent for an inlet concentration of
5,742 ppm and an outlet concentration of 13.3 ppm (Hall, 1993). The flow rate was not reported
for this tested unit; however, exhaust flow rates from storage vents are probably in the several-
hundred-ftVmin range when being filled. Polymerization was not encountered for the adsorbent
used in these applications.
Applicability to FRP/C/C Processes. The SORBATHENE® technology would not be
economically feasible for the typical low-concentration and high-flow rate exhaust encountered
in the FRP/C facilities. A SORBATHENE® unit might be used after the exhaust stream has been
concentrated and its flow rate reduced by a preconcentration unit; however, its feasibility will be
determined by the economic value, quantity, and reusability of the recovered styrene.
Cost. Larry Larrinaga (Radian International, personal communication, September 9,
1996) estimated that the equipment costs for a SORBATHENE unit treating an optimal flow rate
of 300 to 500 ftVmin would range from $600,000 to $800,000. The SORBATHENE® unit is
very sensitive to flow rate and the equipment cost increases dramatically as the flow rate
increases. Operating costs include electricity cost to operate the adsorbers, vacuum pump,
condenser, and separator.
References
Collide S.J., DJ. Pezolt, and L. Larrinaga. 1996. Capture and Recovery of Tetrafluoromethane
and Hexafluoroethane from Industrial Vents. Presented at the Air & Waste Management
Association 89th Annual Meeting, Nashville, TN, June 23-28.
Hall, T.L. 1993. Dow Chemical SORBATHENE? Solvent Vapor Recovery Unit. Presented at
American Chemical Society, Emerging Technologies in Hazardous Waste Management, Atlanta,
GA, September 29, 1993.
11
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Chapter 4
OSHA Regulations and Policies Affecting Worker Exposures in FRP/C and
Boat Building Industries
OSHA regulations governing the permissible exposure limit (PEL) for styrene and the
ventilation system design in the FRP industry were summarized and presented in an RTI report
(Kong et ah, 1996). That report also concluded that concentrating the exhaust air stream and
reducing the exhaust flow would reduce the cost of control. However, the worker exposure is
bounded by OSHA's PEL for styrene. The current 8-hour time-weighed-average (TWA) PEL for
styrene is 100 ppm. The TWA short-term exposure limit (STEL) is 200 ppm for 15 minutes
during,a work day and 600 ppm for 5 minutes in any 3 hours.
John B. Jenks, the Chairman of the Society of the Plastics Industry, Inc.'s Styrene
Information & Research Center, and several industry officials sent a letter to Joseph A. Dear, the
Assistant Secretary of Labor for OSHA, on January 29, 1996, and declared a willingness to
voluntarily comply with lower exposure limits than those set by OSHA in its January 1989 rule
on PEL for styrene and other air contaminants (OSHA, 1996). The lower limits are 50 ppm for
an 8-hour TWA and 100 ppm for short-term exposure. The industry groups volunteering to
lower exposure limits are the Society of the Plastics Industry, Inc.'s Composites Institute,
Composites Fabricators Association, National Marine Manufacturers Association, and
International Cast Polymer Association. These industry groups use polyester resins that emit
styrene in the production processes. The goal is for these industry groups to comply with the
lower exposure limits by July 1997.
As the worker exposure limits are lowered, more efficient exhaust systems will be needed
to remove the same amount of emissions or employees who may not presently be wearing
respirators will need to wear them. General ventilation, also called dilution ventilation because it
uses fresh air to achieve lower worker exposure levels, is not practical and would be expensive in
the winter when makeup air is heated to maintain a constant temperature for product quality.
Therefore, new air flow management practices to remove styrene emissions effectively or a
respiratory protection program will be necessary to comply with lower exposure limits.
This section presents (1) the summary and implication of OSHA regulations related to
styrene emissions and ventilation in the FRP industry, (2) the explanation for "de minimis
violations" under the OSHA policy, and (3) local air flow management practices and
modifications to spray booths that could be considered for the ventilation and worker exposure
issues.
4.1 Summary and Implication of OSHA Regulations
If a facility does not have a designated booth or area for gel coating and resin application
in an open molding process, the emissions from these operations will be dispersed in the work
12
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area and the surrounding open space. Under these conditions, the worker exposures are limited
to the styrene PELs listed in Table Z-2 in 29 CFR § 1910.1000 (OSHA, 1993) or as shown
above. Title 29 CFR § 1910.1000 (e) states that administrative or engineering controls (e.g.,
enclosure or confinement of the operation, general and local ventilation, and substitution of less
toxic materials) must first be determined and implemented whenever feasible. When such
engineering controls are not feasible to achieve full compliance or while they are being instituted,
protective equipment or any other protective measures should be used to keep the exposure of
employees to air contaminants within the limits prescribed in the section. Whenever respirators
are used, their use should comply with requirements in 29 CFR § 1910.134 "Respiratory
Protection."
When a facility uses a spray booth, its design must comply with regulations in 29 CFR §
1910.94 (c) and § 1910.107. Section § 1910.94 (c) lists the design and construction of the spray
booth and the minimum air flow velocities that must be designed and maintained at the entrance
to the spray booth under various operating conditions in order to meet health and safety
requirements. Section § 1910.107 is adopted by OSHA from National Fire Protection
Association (NFPA) 33-1969 (NFPA, 1969) "Standard for Spray Finishing Using Flammable and
Combustible Materials." The NFPA-33 standard is explicitly a fire and explosion safety
standard. Therefore, the OSHA standard at 29 CFR § 1910.107 pertains to the prevention of
workplace fire and explosion hazards and does not pertain to health considerations.
Because the industry has volunteered to comply with lower PELs, facilities having
difficulty meeting the lower limits will have to build spray booths for their styrene-emitting
operation, apply air flow management to exhaust styrene emissions, or provide respirators for
employees who could be exposed to styrene concentrations above the PELs. These facilities will
choose one of these options based on the feasibility of using engineering controls, building spray
booths, applying air flow management practices, changing material/equipment/process, or
providing personal respirators. When the employee exposures are above the PELs, as determined
by personal sampling, the employer can work with the OSHA compliance officer to determine a
schedule for an interim abatement system (e.g., providing respirators to employees) and a long
term abatement system (e.g., building a ventilation system). Feasibility of the abatement systems
will be considered by the facility operator and the compliance officer in meeting the PELs. If
worker exposures still can not meet PELs after engineering controls have been employed, then
the respiratory program will become a permanent program (Smith, OSHA, personal
communication, October 15, 1996).
4.2 De Minimis Violations
According to the OSHA policy (Shepich, 1990), de minimis violations are violations of
standards that have no direct or immediate relationship to employee safety or health. Whenever
de minimis conditions are found during an inspection, they are documented the same way as any
other violation but are not included on the citation. De minimis violations result in no penalty
and no required abatement. The criteria for finding a de minimis violation are as follows:
13
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An employer complies with the clear intent of the standard but deviates from its particular
requirements in a manner that has no direct or immediate relationship to employee safety and
health. These deviations may involve distance specifications, construction materials
requirements, use of incorrect color, minor variations from recordkeeping, testing, or
inspection regulations, or the like.
An employer complies with a proposed standard or amendment or a consensus standard
rather than with the standard in effect at the time of the inspection when the employer's
action provides equal or greater employee protection.
An employer's workplace is at the "state of the art" that is technically beyond the requirement
of the applicable standard and provides equivalent or more effective employee safety or
health protection.
Under an OSHA policy for de minimis violations, employers are encouraged to abide by
the standard applicable to their operations that provides equal or greater employee protection
rather than with the OSHA standard in effect at the time of the inspection.
4.3 Local Air Flow Management and Spray Booth Modifications
The most effective way to reduce worker exposure is to directly remove styrene emissions
from the source before the pollutants have a chance to disperse. Local air flow management,
such as local extraction ventilation or a spray booth, removes emissions at the source and
therefore reduces the amount of air to be exhausted and the amount of makeup air to be heated.
Several local extraction ventilation systems are presented in the earlier report (Kong et al., 1996).
These local extraction ventilation systems apply the push-pull ventilation principle in that fresh
makeup air is admitted at one end of the work area and the air current picking up the emissions is
exhausted at the other end of the work area. An operator can reduce unnecessary exposure by
staying in the upwind side of the ventilated work area.
As the EPA Office of Air Quality Planning and Standards (OAQPS) develops maximum
achievable control technology (MACT) standards for the FRP industry, new facilities using
greater than a certain quantity of resin and gel coat in an open molding process may be required
to reduce their emissions. Emissions from concentrated sources in certain operations, such as
continuous lamination, pultrusion, and SMC production, can be captured and exhausted using a
vent hood. Emissions from other open molding processes, such as gel coating and resin sprayup,
need to be confined in a spray booth that meet OSHA's requirements. A spray booth can be
designed to meet the requirements of a total enclosure so that the emissions can be completely
captured. In this case, fresh makeup air should be supplied to the operator's breathing zone in
the spray booth.
If the worker exposures are still higher than the PELs after proper engineering controls
(i.e., confinement, local extraction, or general ventilation) have been implemented, then the
operator should wear a respirator or a positive-pressure respirator with fresh uncontaminated air
supply. The fresh air supplied to a positive-pressure respirator should meet certain air quality
14
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requirements and if the air is supplied by an oil-based compressor there must be a CO alarm to
detect CO in the air (Smith, OSHA, personal communication, October 15, 1996).
It is common for the employers of some large FRP and boat building facilities to provide'
respirators to their employees for additional protection even though they may in compliance with
the PELs. Positive-pressure respirator with full body protection and fresh air supply is not
common in the FRP and boat building industries; however, such a system is used in an enclosed
paint booth in Hatteras Yachts in New Bern, North Carolina.
Modifications to spray booths, such as a split flow recirculation, have been examined in a
large painting booth at a military installation (Hughes et al., 1994). A portion of the exhaust
from the spray booth that contain less pollutants is recirculated to the front of the spray booth
after mixing with fresh makeup air. The concentration in the return air is less than the PELs.
The balance of the exhaust, which is at a higher concentration, is vented to an add-on emission
control device. The purpose of recirculation is to increase the outlet concentration and reduce the
exhaust flow so that the capital and operating costs of the add-on control can be minimized. The
recirculating air can be returned to the spray booth at any point, either mixed with fresh makeup
air or not mixed with fresh makeup air. In the latter case, the fresh makeup air can be supplied to
the breathing zone of the operator to provide the most protection. Although recirculation in the
spray booth is not recommended by OSHA, the bottom line is that worker exposures should not
exceed the PELs (R. Fairfax, Health Compliance Program, Occupational Safety and Health
Administration, personal communication, September 9, 1996).
If all forms of air flow management are not feasible, a facility should consider
preconcentrating the exhaust stream to reduce the flow rate and to increase the concentration of
the exhaust stream for an add-on control. Preconcentration reduces not only the capital cost but
also the operating cost of the add-on control; it also reduces natural gas usage and generates
fewer secondary pollutants than straight thermal oxidation of the entire exhaust stream. An
analysis of secondary pollution and natural gas usage for various control options is presented in
Chapter 5.
References
Hughes, S., J. Ayer, and R. Sutay. 1994. Demonstration of Split-Flow Ventilation and
Recirculation as Flow-Reduction Methods in an Air Force Paint Spray Booth, AL/EQ-TR-1993-
0002, Armstrong Laboratory, Environics Directorate, Tyndall AFB, FL.
Kong, E.J., M.A. Banner, and S.L. Turner. September 1996. Assessment ofStyrene Emission
Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640),
Research Triangle Park, NC.
National Fire Protection Association (NFPA). 1969. Standard for Spray Finishing Using
Flammable and Combustible Materials, NFPA 33. Quincy, MA.
15
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OSHA (Occupational Safety and Health Administration). 1993. Occupational Safety and Health
Standards. 29CFR1910. Code of Federal Regulations. Washington, DC: Office of the Federal
Register, July 1.
OSHA (Occupational Safety and Health Administration). 1996. OSHA Announces that Styrene
Industry has Adopted Voluntary Compliance Program to Improve Worker Protection. News
Release USDL:96-77, March 1.
Shepich, TJ. 1990. Directorate of Compliance Programs, Occupational Safety and Health
Administration. Letter to S.R. Wyatt, Emission Standards Division, U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC,
January 16.
16
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Chapter 5
Assumptions in the Society of Plastics Industry/Composites Institute's
(SPI/CI) Study on Noneconomic Impacts of Incineration Controls
Energy use and generation of secondary pollution for control devices are dependent on
the type of control device selected and the flow rate into the control device. The SPI/CI Study on
Non-Economic Impacts of Incineration Controls (Haberlein, 1996) was based on thermal
oxidation of a 30,000 ftVmin exhaust stream containing 20 ppm of styrene. The following
sections discuss the assumptions of a thermal oxidizer operating on a stream containing 20 ppm
of styrene. Appendix A contains a discussion of other assumptions in the SPI/CI study.
5.1 Use of Thermal Oxidizer
The SPI/CI study assumes a thermal oxidizer operating on a stream containing 20 ppm of
styrene. However, previous RTI analyses of the costs of controls has indicated that pre-
concentration/oxidation systems have lower annualized costs than straight thermal oxidation for
control device inlet concentrations below approximately 300 ppm. For example, Figure 5-1
shows RTI-calculated control costs for thermal oxidation, catalytic oxidation, and three pre-
concentration/oxidation systems, for a plant with uncontrolled emissions of 400 ton/yr (operating
4,000 h/yr).1 Figure 5-1 shows that the three preconcentration/oxidation technologies (MIAB,
Polyad, and Durr rotary concentrator systems) have lower total costs per unit of styrene removed
than straight thermal oxidation or catalytic oxidation. Therefore, it is likely that an FRP
company would choose a preconcentration/oxidation system over straight thermal oxidation for
an exhaust stream containing 20 ppm styrene based on lower total annualized cost. It is also
likely that an FRP company would attempt to increase the styrene concentration (i.e., lower the
flow rate), compared to the 20-ppm assumption in the SPI/CI study. This point is discussed in
the following section.
5.2 Control Device Inlet Concentration of 20 ppm
Noneconomic impact analyses in the SPI/CI study are based on an assumed styrene
concentration of 20 ppm to a thermal oxidizer. To evaluate this assumption, RTI reviewed the
following: (1) economic incentives for maximizing inlet concentrations (minimizing flow rates)
to end-of-pipe controls, (2) plant-wide average exhaust concentrations currently found at FRP
plants, (3) recent and possible future changes to allowable exposure levels for employees of FRP
plants, (4) existing relationships between employee exposures to styrene and exhaust
concentrations at FRP plants, and (5) possible methods for new plants to increase concentrations
(decrease flow rates) to controls while maintaining or lowering employee exposures.
1 Figure 5-1 is based on a cost curve presented in a previous EPA report (Kong et al., 1996), with
corrections as discussed in Appendix B to this report.
17
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246,000
123,000
Flow rate,cfm (1 cfm = 0.0283 m3/min)
61,500 41,000 30,750 24,600
20,500
17,600
MIAB
• • - Polyad (w/oxidation)
Catalytic oxidizer (95% H.R. below 100 ppm)
Thermal oxidizer (95% H.R.)
— — Durr rotary concentrator
•g 4,000
100
200
300 400
Concentration (ppm)
500
600
700
Figure 5-1. Cost curves for a large plant (400 tons per year inlet).
-------
5.2.1 Economic Incentives for Maximizing Inlet Concentrations
Previous RTI research demonstrated the economic desirability for a plant considering
installation of end-of-pipe controls to evaluate methods to minimize flow rate prior to choosing
any form of end-of-pipe controls. This is demonstrated by Figure 5-1, where the total annualized
cost per unit of styrene removed decreases for all control choices as flow rate is reduced (i.e., as
concentration increases). This trend is true even for preconcentration/oxidation systems (i.e.,
even for preconcentration/oxidation systems, the total annualized cost is reduced when design
flow rate is reduced). Therefore, companies that contemplate end-of-pipe controls would find
significant economic benefits in increasing control device inlet concentration above 20 ppm, with
the associated reduction in total flow to the control device.
5.2.2 Exhaust Concentrations at Existing Plants
The SPI/CI study was based on a hypothetical exhaust stream averaging 20 ppm. One
way to evaluate the appropriateness of this concentration is to look at average facility-wide
exhaust concentrations at existing facilities. Research Triangle Institute and Pacific
Environmental Services conducted an evaluation of facility-wide styrene exhaust concentrations
currently found at fiber-reinforced plastics facilities with open-mold spraying operations. The
results of this evaluation are presented in Table 5-1. Table 5-1 contains only facilities with
annual (neat, or unfilled) resin-plus-gel-coat usage of greater than approximately 1,000 tons per
year.
Average facility-wide exhaust concentrations in Table 5-1 are calculated based on
facility-wide emissions (in mass per year), total facility exhaust flow rate, and facility operating
schedule (hours per year). Where possible, values in Table 5-1 for emissions and flow rates are
based on testing data. Otherwise, resin/gel coat usage and emission factors are used to calculate
emissions for subsequent exhaust concentration calculations.
Table 5-1 shows that all eight facilities evaluated currently have average exhaust
concentrations above 20 ppm. The mean value for the eight facilities is 120 ppm, and the median
value is 82 ppm.
Two of the eight facilities listed in Table 5-1 have controls. The A.R.E. facility in
Massillon, Ohio, which has a thermal oxidizer, has a calculated average styrene concentration of
231 ppm in the flow stream to the control device. The American Standard facility in Salem,
Ohio, which has a Polyad preconcentration/catalytic oxidation system, has an average styrene
concentration of 75 ppm flow stream to preconcentrator.
In summary, existing facilities with open-mold spraying and combined resin/gel coat
usage above 1,000 ton/yr typically have average exhaust concentrations that are above the 20
ppm assumed in the SPI/CI study.
19
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Table 5-1. Styrene Exhaust Concentrations at Existing Open Molding Plants with Resin/Gel Coat Usage Greater than 1,000 tons/yr
PLANT NAME
AQUA GLASS
A.R.E., INC.
LASCO BATHWARE
UNIVERSAL RUNDLE
AMERICAN STANDARD
A.R.E., INC.
MILLENIUM PRODUCTS
AQUA GLASS
Arithmetic mean
Median
CITY
KLAMATH FALLS
MASILLON
MOAPA
OTTUMWA
SALEM
MOUNT EATON
ELKHART
ADAMSVILLE
ST
OR
OH
NV
IA
OH
OH
IN
TN
UNCONTROLLED
EMISSIONS (ton/yr)
1,175
770
739
328
53
108
123
1,151
OPERATING
HOURS (h/yr)
6,000
7,488
4,290
4,160
2,500
3,120
2,000
6,000
PLANT-WIDE
FLOW RATE
(ft3/min)
97,000
55,000
155,400
1 10,700
35,000
70,000
125,000
390,000
AVERAGE
STYRENE
CONCENTRATION
(ppm)
249
231
137
88
75
61
61
61
120
82
10
o
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5.2.3 Recent and Potential Future Changes in Allowable Exposures to Styrene
Currently, OSHA PELs for styrene are 100 ppm as an 8-hour time-weighted-average
(TWA) and 200 ppm as a 15-minute short-term-exposure-limit (STEL). The SPI/CI study notes
that the reinforced plastics industry has voluntarily agreed to meet a 50-ppm TWA and a 100-
ppm STEL. Compliance with the agreement will go into effect in July 1997. The SPI/CI study
further notes that the American Council of Government Industrial Hygienists (ACGIH) has
placed styrene on the Notice of Intended Change list to lower the styrene threshold limit value
(TLV) to 20 ppm, with a STEL of 40 ppm.
The SPI/CI study uses a control device inlet concentration of 20 ppm. This is equal to the
TLV being proposed by the ACGIH. RTI has no information to indicate that OSHA currently
plans to lower the TWA to 20 ppm.
5.2.4 Existing Relationships Between Worker Exposure and Exhaust Concentration
Even if the OSHA TWA were lowered to 20 ppm, it would be reasonable to assume that a
company building a new facility would have an average exhaust concentration to an end-of-pipe
control that would be above 20 ppm. One reason for this is the strong economic incentive to
maximize concentration (minimize flow rate), as discussed in Section 6.1. Another reason for
this is that most capture systems would logically be oriented to draw styrene away from the
worker, rather than drawing styrene into the worker's breathing zone. This concept is illustrated
in Figure 5-2.
Currently, there is little available data relating average exhaust concentrations to worker
exposures. Some data are available from the Lasco-South Boston (Virginia) tub-and-shower
facility, and are presented in Table 5-2. Table 5-2 indicates that gel coat gun operators and
lamination rollers had the highest average worker exposures during the measurement period and
that the average ratio of exhaust-duct-concentration-to-worker-exposure was 2.36 and 2.42,
respectively.
RTI is analyzing data collected at a tub-and-shower facility in which employee exposure
and exhaust duct concentration were measured simultaneously. The results of this testing are
expected to be published by February 1997 (see Section 5.2.5).
5.2.5 Potential Methods to Increase Concentration to Downstream Controls
Previous research by RTI identified several potential methods to decrease required flow
rates for end-of-pipe controls while preventing excess employee exposure levels. These methods
included: (1) local air flow management, (2) spray booth modifications (such as split-flow spray
booths and spray booth recirculation), and (3) enclosures and total enclosures.
RTI is currently analyzing data from proof-of-concept testing at a tub-and-shower facility.
This testing is evaluating the ability of spray enclosures and air flow management techniques to
increase exhaust duct concentration while
21
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Main Filter Bank
Main Exhaust to Atmosphere
(high volume, low concentration)
Fresh Air Supply
Figure 5-2. Typical open molding operation in a spray booth.
-------
Table 5-2. Comparison of Average Styrene Exhaust Concentration (290 ppm) (Strum,
1995) With Worker Exposure Levels (Boyd, 1995) at Lasco Bathware, South Boston, VA
Job Category
1 . Gel Coat Gun Operator
2. Lamination Gun Operator
3. Lamination Roller
4. Barrier Coat
Gun Operator
5. Part Puller
6. QC Technician
7. Mixer
8. Trimmer
9. Waxer
Number of
Measurements*
5
17
6
5
2
4
5
1
1
Exposure
Range*
(ppm)
88-199
37-267
92-142
61-105
32-39
23-75
15-44
Average
Exposure*
(ppm)
123.0
90.4
120.0
79.4
35.3
37.0
31.6
46.0
25.0
Average Ratio,
Exhaust/Exposure
2.36
3.21
2.42
3.65
8.22
7.84
9.18
6.30
11.60
Data provided to Madeleine Strum by Daniel Boyd (Boyd, 1995).
maintaining or lowering worker exposures. The enclosure concept involves placing a part inside
an enclosure while the spray gun operator stands outside the enclosure. The air flow
management techniques involve the use of a close-capture exhaust panel. In this testing, one
flame ionization detector (FID) device continuously measured exhaust duct concentration while
another (portable) FID was used to continuously monitor worker exposure. In this manner, the
ratio of exhaust duct concentration to worker exposure concentration could be continuously
monitored and compared with "baseline" results from an unmodified spray booth. The results of
the RTI enclosures/air flow management testing are expected to be available by February 1997.
5.2.6 Conclusions on Assumption of Control Device Inlet Concentration of 20 ppm
There are strong economic incentives for a company to maximize the concentration
(minimize the flow rate) to a control device. Most existing facilities with open-mold spraying
(even those without controls) currently have exhaust concentrations well above 20 ppm.
Lowering allowable worker exposure levels can force lower concentrations to a control device.
However, it appears likely that, even for worker exposure levels of 20 ppm, minimum exhaust
concentrations on the order of 50-100 ppm could be achieved with current, or slightly improved,
air flow management practices. Therefore, the assumption of a control device inlet concentration
of 20 ppm appears to be too low.
23
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References
Boyd, D., Daniel P. Boyd & Company, 1995. Presentation for the U.S. Environmental Protection
Agency's site visit at Lasco Bathware - South Boston (VA), June 22.
Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced
Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, MI.
Strum, M., U.S. Environmental Protection Agency, 1995. Site Visit Report -- LASCO Bathware,
South Boston, VA.
24
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Chapter 6
RTI Analysis of Noneconomic Impacts of Controls
RTFs analysis of noneconomic impacts of controls includes the development of
normalized curves to predict noneconomic impacts. Noneconomic impacts are also calculated
for a specific, typical existing facility that has gel coat and sprayup processes.
6.1 Normalized Curves for Natural Gas Usage and Secondary Pollutant Emissions
To compare energy usage and secondary pollutant emissions for various flow rates and
styrene mass emission rates, we must "normalize" the data. Data presented in Section 6.1 have
been "normalized" to reflect fuel usage and secondary pollutant emissions per ton of styrene
removed (based on 95 percent removal efficiency).
Most of the figures in this section include the following control options: (1) a thermal
oxidizer, with 95 percent heat recovery, operating at 1,800 °F (as assumed in the SPI/CI study);
(2) a thermal oxidizer, with 95 percent heat recovery, operating at 1,500 °F (which could produce
a styrene destruction efficiency of 95 percent); (3) a catalytic oxidizer, with 95 percent heat
recovery, operating at 650 °F (which could produce a styrene destruction efficiency of
95 percent); and (4) a preconcentrator/catalytic oxidizer, based on the Polyad system, that has a
natural gas requirement of 96,000 Btu/h at 30,000 ftVmin. (The Polyad system requires
96,000 Btu/h to desorb styrene, for a system with an inlet flow of 30,000 ft3/min.)
The figures in this section can be used in the following manner: In Figure 6-1, the natural
gas usage for a thermal oxidizer operating at 1,800°F, with an inlet concentration of 20 ppm, is
approximately 650,000 ft3 per ton of styrene removed. Therefore, if a thermal oxidizer removed
100 tons of styrene under these conditions, the natural gas usage would be 65 million cubic feet.
Similarly, from Figure 6-1, the natural gas usage for a preconcentrator/oxidizer operating with a
styrene inlet concentration of 100 ppm is approximately 4,200 ft3/ton of styrene removed.
Therefore, if a preconcentrator/oxidizer removed 100 tons of styrene under these conditions, the
natural gas usage would be 420,000 ft3.
6.1.1 Natural Gas Usage
Figure 6-1 presents normalized curves for natural gas usage for various control options.
Figure 6-1 also contains normalized curves for the sensible heat required to raise an exhaust
stream from average outdoor temperatures to an indoor temperature of 75 °F for two locations
(i.e., Fort Wayne, Indiana, and Los Angeles, California). The curves for sensible heating
requirements are included to compare the additional natural gas usage for controls with existing
natural gas for heating.
In Figure 6-1, the top left point of the four control-option curves represents the
assumptions in the SPI/CI study (i.e., a thermal oxidizer, with 95 percent heat recovery, operating
25
-------
1000
•o
o>
§
o
w
O
2
g
o
g>
§
ro o>
<* 2
100
— — Thermal oxidizer (Habertein: 1800 oF)
Thermal oxidizer (RTI: 1500 oF)
Catalytic oxidizer (RTI: Heat recovery = 95%, 650 oF)
""^"""Preconcentrator/oxidizer (Polyad: Desorption = 96,000 Btu/h @ 30,000 cfm)
"" "" Sensible heat for Fort Wayne, Indiana
Sensible heat for Los Angeles, California
20 40 60 8.0 100 120 140 160
Styrene inlet concentration (ppm)
180
200
220
240
260
Figure 6-1. Normalized natural gas usage for various control
options and for sensible heating of exhaust stream.
En Chart 2
-------
at 1,800 °F, with an inlet concentration of 20 ppm). The natural gas requirement for this point is
approximately 650,000 ftVton of styrene removed. In contrast, for a preconcentrator-catalytic
oxidizer operating at 88 ppm, the natural gas requirement is approximately 5,000 ftVton of
styrene removed.
Figure 6-1 illustrates that the natural gas usage for a preconcentrator/catalytic oxidizer is
actually less than the sensible heat required to heat an equal flow rate to 75 °F, in Fort Wayne,
Indiana, or Los Angeles, California.
6.1.2 Carbon Dioxide Emissions
Figure 6-2 presents normalized carbon dioxide emissions for four control-option curves.
In Figure 6-2, the top left point of the four curves represents the assumptions in the SPI/CI study
(i.e., a thermal oxidizer, with 95 percent heat recovery, operating at 1,800 °F, with an inlet
concentration of 20 ppm). The carbon dioxide generated by natural gas combustion for this point
is approximately 41 ton/ton of styrene removed. In contrast, for a preconcentrator-catalytic
oxidizer operating at 88 ppm, the carbon dioxide generated by natural gas combustion is
approximately 0.33 ton/ton of styrene removed.
All of the curves in Figure 6-2 depict only the carbon dioxide emissions generated by
burning natural gas to destroy styrene. These curves do not include the carbon dioxide created
naturally by the degradation of styrene. Chemical stoichiometry dictates that every ton of styrene
converts to 3.38 tons of carbon dioxide.
6.1.3 Nitrogen Oxide Emissions
The SPI/CI study assumed 15 ppm of nitrogen oxides (NOX) are emitted from the thermal
oxidizer. This was based on the following numerical values, as reported by Haberlein
(Haberlein, 1996):
• 50-100 ppm, as reported by CVM
• 10-15 ppm, as reported by Wheelabrator
• 13 ppm, as reported by Tellkamp
• <10 ppm, as reported by Huntington.
RTFs research appears to indicate that values of less than 10 ppm are probably more
typical for thermal oxidizers, particularly if the oxidizer operates at approximately 1,500 °F, and
especially if the oxidizer uses technology to reduce NOX emissions, such as low-NOx burners.
Specifically, RTI's research indicates the following:
• Smith Engineering stated that none of the 25 installations for which they have
NOX measurements has an average concentration over 10 ppm.
• Durr Industries provided NOX emissions test data for two installations. Both
installations had average NOX emissions less than 10 ppm. The time-weighted
27
-------
100.00
c
o
I
w
0)
Q.
•o
S
S
2
X
_o
•o
§
10.00
1.00
K>
00
•o
a
JO
0.10
0.01
— - — - Thermal oxidizer (Haberlein: 1800 oF)
• • • Thermal oxidizer (RTI: ISOOoF)
Catalytic oxidizer (RTI: HR=95%, 650 oF)
••"""• Preconcentrator (Polyad: Desorption = 96,000 Btu/h @ 30,000 cfm)
A Haberlein (20 ppm inlet styrene, thermal oxidizer, 1800 oF)
• Existing plants
20
40
80
100 120 140 160
Styrene Inlet concentration (ppm)
180
200
220
240
260
Figure 6-2. Normalized additional* carbon dioxide generated by natural gas combustion for
various control options.
* "Additional" means that the values do not include the 3.38 tons of CO2 generated by the conversion of styrene (C8He) to CO2 (i.e., every mole of styrene
[MW=104] generates 8 moles of carbon dioxide [MW=44]).
-------
average NOX generation for a thermal oxidizer installed in an automotive
application was 2.7 ppm (Gupta, 1996).
• Process Combustion Corporation published a paper that concluded, "Various NOX
combustion control techniques are available. With waste gases free of nitrogen-
bound compounds, NOx emissions from thermal oxidation can be reduced to less
than 10 ppm." (Nutcher and Lewandowski, 1994)
• The Institute of Clean Air Companies noted that operation of a thermal oxidizer
should result in less than 10 ppm of NOX (Wax, 1995).
Fewer data are available for NOX emissions from catalytic oxidizers. RTI investigation of
this subject yielded the following:
• Englehard Process Emission Systems (South Lyon, Michigan) published a paper
that concluded that a catalytic oxidizer produces 0 to 2 ppm of NOX contribution
(Gribbon, 1996).
• The Institute of Clean Air Companies noted that catalytic oxidizers run at much
lower temperatures than thermal oxidizers (and should therefore produce less
NOX).
Figure 6-3 shows normalized NOX emission curves for various control technologies.
There are actually three NOX curves for thermal oxidation, based on three different assumptions
for NOx outlet concentration. The top curve represents an assumption of 15-ppm outlet NOX, as
assumed in the SPI/CI study. The middle thermal-oxidation curve represents an assumption of
8.8-ppm outlet NOX, as quoted from Smith Engineering. The bottom thermal-oxidation curve
represents an assumption of 2.7-ppm outlet NOX, as measured in the May 1995 testing by Durr
(Gupta, 1996).
6.2 Calculations for Specific Plant
Bar graphs depicting energy use and secondary pollutant emissions are presented for a
specific plant: the Universal Rundle plant in Ottumwa, Iowa. This plant has calculated
characteristics as shown in Table 6-1.
The Universal Rundle plant in Ottumwa, Iowa, has a calculated uncontrolled styrene
exhaust concentration of 88 ppm, and a flow rate of 110,700 ftVmin. For each bar graph, there is
one bar representing a concentration of 20 ppm and a flow rate of 487,080 ftVmin. This 487,080
ftVmin flow rate represents the flow rate that would occur if emissions were diluted from the
actual value of 88 ppm to the hypothetical value of 20 ppm assumed in the SPI/CI study.
29
-------
1.0000
0.1000
•o
I
g
2
IT
•*• 0.0100
o
c
2
h.
0
a.
•o
aj
2
o
c
§>
o"
I
o
33
a
CE
0.0010
0.0001 :
0.0000
Thermal oxidizer (Haberlein: 15 ppm NOx)
— —Thermal oxidizer (Smith Engineering verbal: 8.8 ppm NOx)
" " • Thermal oxidizer (Durr Environmental testing: 2.7 ppm NOx)
Catalytic oxidizer (Salem Englehard verbal: 1 ppm NOx)
"""^•^Concentrator/Catalytic Oxidizer (Concentration ratio of 10 to 1,1 ppm NOx)
A Haberlein (Thermal oxidizer, 20 ppm inlet styrene, 15 ppm outlet NOx)
• Existing plants
20 40 60 80 100 120 140 . 160
Inlet styrene concentration (ppm)
180
200
220
240
260
Figure 6-3. Normalized NOX emissions for various control options.
Chart 1
-------
Table 6-1. Characteristics for Specific Plant (Universal Rundle, in Ottumwa, Iowa)
Characteristic
Uncontrolled styrene emissions
Assumed control efficiency
Control device inlet concentration
Air flow rate into control device
Operational schedule
Value
328 ton/yr
95 percent (i.e., 312 ton/yr of styrene
removed, and resulting controlled emissions
of 16 ton/yr).
88ppm
11 0,700 tf/min
4,160 h/yr
6.2.1 Natural Gas Usage
Figure 6-4 compares natural gas usage for several control options and for sensible heating
for the specific plant. The bar on the left side of the page represents the natural gas that would be
used if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in the
SPI/CI study. All other bars represent the actual plant flow rate of 110,700 ftVmin.
Figure 6-4 indicates that the natural gas used in annual heating for an exhaust flow of
110,700 ftVmin is approximately 3.6 million ftVyr (based on heating requirements in Fort
Wayne, Indiana). In contrast, the natural gas requirement for the preconcentrator/catalytic
oxidizer option (which is based on the Polyad system), is approximately 1.5 million ftVyr. It
should be noted that the calculated value of 3.6 million ftVyr for sensible heating of the exhaust
stream does not reflect all the heating requirements for an FRP facility. Additional heating
would be required to replace heat losses through the walls and ceiling of the facility. Natural gas
might also be used for latent heating, if humidification is required during the winter.
The calculations for natural gas usage in Figure 6-4 can be compared with total natural
gas usage in the United States in 1995. The total natural gas usage in the United States in 1995
was approximately 2.2 x 1013 ft3, which is approximately a factor of 100,000 times greater than
the natural gas usage of the highest option shown in Figure 6-4.
6.2.2 Carbon Dioxide Emissions
Figure 6-5 presents carbon dioxide emissions for several control options for the specific
plant. The bar on the left side of the page represents the carbon dioxide that would be produced
if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in the
SPI/CI study. All other bars represent the actual plant flow rate of 110,700 ftVmin.
31
-------
250,000,000
200,000,000
u>
to
) 150,000,000
10
3
co
a
at
f 100,000,000
a
50,000,000
D Natural gas used in oxidation, cubic feet/year
• Natural gas used in sensible heating, cubic feet/year
Thermal
(1800 oF),
20 ppm sty
487,080 cfm
Thermal
(1800oF),
88 ppm sty
110,070 cfm
Thermal
(1,500oF),
88 ppm sty
110,700 cfm
Catalytic
(650 OF), 88
ppm sty
110,700 cfm
Concentrator
+ Catalytic,
88 ppm sty
110,700 cfm
Figure 6-4. Natural gas usage for various control options and for sensible heating at a typical
plant (basis: 328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr)
sty = inlet styrene concentration
NGbar.,
I Chart 1
-------
16,000
14,000
12,000
.. 10,000
t
o
% 8,000
J2
o
o"
0 6,000
4,000
2,000
Thermal
(1800oF),
20 ppm sty
487,080 cfm
Thermal
(1800oF),
88 ppm sty
110,070 cfm
DCO2 from natural gas used in oxidation, tpy
& CO2 from natural gas used in heating, tpy
0CO2 from styrene decomposition, tpy
Thermal
(1,500oF),
88 ppm sty
110,700 cfm
Catalytic
(650 oF), 88
ppm sty
110,700 cfm
Figure 6-5. Carbon dioxide emissions for various control options at a typical plant (basis:
328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr).
Concentrator
+ Catalytic,
88 ppm sty
110,700 cfm
sty = inlet styrene concentration
CO2bar Chart 1
-------
Each bar in Figure 6-5 has three components: 1) the CO2 produced by natural gas used in
oxidation, 2) the CO2 that would be produced by burning natural gas to heat the flow stream from
the average outdoor temperature to 75 °F, and 3) the CO2 produced from the stoichiometric
degredation of styrene to CO2 (and water).
The bar on the left side of the figure represents the CO2 that would be produced assuming
straight thermal oxidation of a 20 ppm flow stream. In order to reduce the concentration from
the actual value of 88 ppm, it would be necessary to increase the exhaust flow from the actual
value of 110,700 ftVmin to a hypothetical value of 487,080 ftVmin. The total CO2 produced in
this hypothetical situation would be over 14,000 tons/yr, of which approximately 12,000 tons/yr
would be due to natural gas used for oxidation.
Other bars in Figure 6-5 reflect the actual exhaust conditions for the plant
(110,700 ftVmin at 88 ppm). The bar on the far right presents the CO2 emissions from a
preconcentrator/catalytic oxidizer. A preconcentrator/oxidizer is the control that would be most
likely to be selected for a flow stream of 110,700 ftVmin at 88 ppm, due to the fact that the
preconcentrator/oxidizer has a lower total annualized cost than the other options. For a
preconcentrator/oxidizer, the total CO2 emissions are approximately 1,400 tons/yr. The vast
majority of these emissions (over 1,100 tons/yr) are due to the stoichiometric degredation of
styrene to CO2. Only 90 tons/yr of CO2 emissions are due to combustion of natural gas used in
heating the air for desorption.
6.2.3 Nitrogen Oxide Emissions
Figure 6-6 presents NOX emissions (as NO2) for several control options for the specific
plant. The bar on the left side of the page represents the NOX emissions that would be produced
if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in SP1/CI
study. All other bars represent the actual plant flow rate of 110,700 ftVmin.
The bar on the right, which is barely visible, indicates NOX emissions for a
preconcentration/catalytic oxidation system. A preconcentration/oxidation system would be the
most likely control choice for a flow rate of 110,700 ftVmin, containing 88 ppm styrene, due to
lower total annualized cost. The NOX emissions for this control option at this facility would be
0.09 tons/yr. This can be contrasted with the estimated styrene removal of 312 tons/yr.
6.2.4 Radon Emissions
Figure 6-7 presents radon emissions from natural gas combustion for several control
options for the specific plant. The bar on the left side of the page represents the radon emissions
that would be produced if the flow rate were raised to 487,080 ftVmin, producing the 20 ppm
value assumed in the SPI/CI study. All other bars represent the actual plant flow rate of 110,700
ftVmin.
34
-------
Thermal
(1800oF),
20 ppm sty
487,080 cfm
Thermal
(1800 oF),
88 ppm sty
110,070 cfm
Thermal
(1,500 oF),
88 ppm sty
110,700 cfm
Catalytic
(650 oF), 88
ppm sty
110,700 cfm
Concentrator
+ Catalytic,
88 ppm sty
110,700 cfm
Figure 6-6. NOx emissions for various control options at a typical plant (basis: 328 ton/yr
uncontrolled styrene emissions and 4,160 operating h/yr)
-------
120,000
jj 100,000
o.
3
X
o
c
O)
o
5
c
I
o
T3
60,000
40-000
20,000
Thermal
(1800oF),
20 ppm sty
487,080 cfm
Thermal
(1800oF),
88 ppm sty
110,070 cfm
Thermal
(I.SOOoF),
88 ppm sty
110,700 cfm
Catalytic
(650 oF). 88
ppm sty
110,700 cfm
Concentrator
+ Catalytic,
88 ppm sty
110,700 cfm
Figure 6-7. Radon emissions due to natural gas combustion for various control options at a
typical plant (basis: 328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr).
sty = inlet styrene concentration
Rador Chart 1
-------
The radon emission calculations in Figure 6-7 are based on an average radon content of
20 pCi/L in natural gas as assumed in the SPI/CI study. This value was also used in a study of
radionuclide emissions from natural-gas fired steam-electric generating plants (Nelson, 1995).
According to the Institute for Clean Air Companies, the Institute for Gas Technology reports
radon levels typically less than 1 pCi/L (Wax, 1996).
6.3 Conclusions
Calculations of noneconomic impacts in the SPI/CI study were based on an exhaust
stream containing 20 ppm of styrene, directed to a thermal oxidizer. However, for economic
reasons, it would be unlikely that a new plant would be designed with a 20-ppm exhaust stream
directed to an end-of-pipe control device. And, if a new plant were designed with a 20-ppm
exhaust stream directed to a control device, a preconcentration/oxidation system would probably
be chosen over straight thermal oxidation, again for economic reasons.
Natural gas usage and secondary pollutant emissions were found to be considerably less
for preconcentration/oxidation systems than for thermal oxidation, in the range from 0 to
approximately 300 ppm of styrene. Since preconcentration/oxidation systems appear to have
lower annualized costs than straight thermal oxidation in this range, the choice of
preconcentration/oxidation systems in this range lowers both economic and noneconomic
impacts.
References
Gribbon, S. T. 1996. Englehard Process Emission Systems; "Regenerative Catalytic
Oxidation," Presented at the 1996 Air & Waste Management Association Specialty Conference
"Emerging Solutions to VOC and Air Toxics Control," Clearwater, FL.
Gupta, A., Durr Industries, Inc., A facsimile on RTO Performance and NOX to Madeleine Strum,
U.S. Environmental Protection Agency, August 6, 1996.
Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced
Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, ML
Nelson, C, Estimates of Health Risks Associated with Radionuclide Emissions from Fossil-
Fueled Steam-Electric Generating Plants, EPA-402/R-95-16 (NTIS PB96-139753), August 1995.
Nutcher, P. B. and D. A. Lewandowsi. 1994. Process Combustion Corporation; "Maximum
Achievable Control Technology (MACT) for NOX Emissions from VOC Thermal Oxidation,"
AWMA paper number 94-WA74A.03, in Proceedings for the Air and Waste Management
Association 87th Annual Meeting and Exhibition, Cincinnati, OH.
Wax, M., Institute of Clean Air Companies, memorandum to Madeleine Strum, U.S.
Environmental Protection Agency, August 11, 1995, Subject: Reinforced Plastic Composites.
37
-------
Wax, M., Institute of Clean Air Companies, memorandum to Mark Banner, Research Triangle
Institute, October 15, 1996, Subject: Radon Concentration in Natural Gas.
38
-------
Appendix A
Comments on Individual Statements in the SPI/CI Study
39
-------
Appendix A
Comments on Individual Statements in the SPI/CI Study (Haberlein, 1996)
1) The (catalytic oxidizer) bed temperature is maintained at about 600 °C (1,100 °F) during
normal operation. (Page ffl-2).
A more typical temperature range for catalytic oxidation of styrene is 600-700 °F (Patkar
etal., 1994).
2) The problem (of catalyst poisoning in a catalytic oxidizer) is severe and unpredictable...
(Pagem-2).
A July 19, 1996 memorandum from Michael Wax (Institute of Clean Air Companies) to
Madeleine Strum (EPA-OAQPS) states that catalyst plugging, poisoning, and
deactivation are well understood, and may be ameliorated through appropriate system
design and operating practices. He refers to an article in the September 1994 issue of
Chemical Engineering, "Extend .the Life of Pollution Control Catalysts," that discusses
in-situ catalyst rejuvenation as an alternative to catalyst replacement.
3) A thermal regenerative incinerator was selected for the hypothetical plant
(30,000 ft3/min, 20 ppm styrene, 8,760 h/yr, 43 tons uncontrolled styrene emissions)
because this type of incinerator has been shown to be the most cost-effective type of
control compared to the recuperative or catalytic (recuperative) types. (Page ni-3).
This analysis ignores the option of preconcentration/oxidation, which appears to have a
lower total annualized cost than any of these options (including regenerative thermal
oxidation), for the hypothetical inlet conditions.
4) For the hypothetical incinerator discussed above...at an oxidation temperature of
1800 °F... (Page ffl-5).
A thermal oxidation temperature of 1,800 °F is compatible with Haberlein's assumed
styrene destruction efficiency of 99 percent. A lower thermal oxidation temperature, such
as 1,500 °F, would be compatible with a lower destruction efficiency, such as 95 percent.
5) The supplemental fuel requirement for an incinerator (with 95 percent heat recovery)
operating at an exhaust flow rate of 30,000 cfin at 20 ppm VOC (and 1,800 °F) is
3,310,000 Btu/h. (Page ffl-5).
The RTI cost spreadsheet for a thermal oxidizer under these conditions produces a
calculated supplemental fuel requirement of 2,984,000 Btu/h, or approximately
10 percent less. This represents fairly close agreement.
40
-------
6) Annual electrical consumption (for the hypothetical thermal oxidizer) is 1,230,000 kWh
(over 8,760 hours). (Page ffl-6).
This represents power usage of 140 kW/h. The RTI cost spreadsheet for a thermal
oxidizer (with 95 percent heat recovery) under these conditions is 125 kW/h, or
approximately 10 percent less. This represents fairly close agreement. RTI's calculation
was based on quotations from Salem Englehard (Mack, 1996).
7) Unfortunately, these compounds (catalyzed resin aerosols and polystyrene-forming
agents) are indeed present in the exhaust streams at most plants, as evidenced by the
solid plastic residue that coats the inner surface of the ductwork in many locations.
Further, no effective means of removing all of these airborne compounds is presently
known. (Page El-13).
Catalyzed resin aerosols are present in many plants, due to spraying operations. These
resin aerosols are actually quite large, and are therefore easily removed by even coarse
filtration. For example, RTI mass-balance testing conducted in June 1995 indicated
approximately 99 percent particle collection by a thin fiberglass veil. It could be expected
that the fiberglass filter pads used at most plants would have an even higher collection
efficiency. RTI has observed that casual fiberglass filter pad installation at many plants
allows gaps or holes in the filter banks. This practice can dramatically lower collection
efficiency, and would need to be avoided. Styrene gas (which can form polystyrene) is
indeed present, and cannot be removed by physical filtration. However, Durr Industries
reports having rotary concentrator systems in Japan that have been running for over 10
years without styrene polymerization.
8) The report (on Polyad) shows an annual 10 % Bonopore (adsorbent) loss out of the
system's cyclone separator. (Page HI-14)
Weatherly, Inc. (manufacturers of Polyad), in a July 18, 1996, memorandum to Madeleine
Strum (EPA-OAQPS), indicated that they now guarantee annual Bonopore loss of
5 percent or less.
9) The calculated energy requirements for a 30,000 scfm Polyad concentrator system are
130 kW, and 96,000 Btu/hr. (Page HI-15).
Weatherly, Inc. (manufacturers of Polyad), in a 1996 memorandum to Madeleine Strum
(EPA-OAQPS), indicated that the electrical requirement would actually be 62 kW, but
the natural gas usage value was correct.
References
Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced
Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, MI.
41
-------
Mack, S., Englehard Corporation, A facsimile on RCO Costs to Mark Bahner, Research Triangle
Institute, February 8, 1996.
Patkar, A.N., J.M. Reinhold, and G. Henderson. 1994. "Demonstration of Capture and Control
Efficiency for a Styrene Emission Source," Paper number 94-RA111.03, in Proceedings for the
Air and Waste Management Association 87th Annual Meeting and Exhibition, Cincinnati, OH.
42
-------
Appendix B
Revision of the Styrene Control Cost Spreadsheet Model and Cost Figures
43
-------
RESEARCH TRIANGLE INSTITUTE
Center for Environmental Analysis
MEMORANDUM
DATE: October 9, 1996
TO: Norman Kaplan, EPA/APPCD/MD-04 cc: Emery Kong (541-5964)
Madeleine Strum, EPA/OAQPS/MD-13
FROM: Mark Banner (541 -6016) /* A 6
SUBJECT: Errors in Styrene Control Cost Spreadsheets and Cost Figures.
Contract 68-D1-0118 (Option IV), work assignment 156. (RTI project 6173-156).
Contract 68-D 1-0118 (Option V), work assignment 192. (RTI project 6684-192).
As a result of activities conducted to prepare an Addendum to the report, "Assessment of
Styrene Controls for FRP/C and Boat Building Industries" (EPA-600/R-96-109), I have discovered
errors in the styrene control cost spreadsheets and in cost curves presented in the report. I do not
believe that these errors significantly affect the accuracy of the spreadsheet total annualized cost
calculations, or alter conclusions of the report. Therefore, per a telephone conversation with
Norman Kaplan today, RTI will not attempt to revise the affected portions of EPA-600/R-96-109.
The errors in the cost spreadsheets are as follows:
1) Polyad System - The cost spreadsheet for the Polyad system was based on electrical
usage of 22 kW at 5,000 cfm, and 59 kW at 15,000 cfm. Weatherly, Incorporated (manufacturer of
Polyad) informed me in December 1995 that actual values would be 12 kW at 5,000 cfm and 32
kW at 15,000 cfm. However, I neglected to change the spreadsheet accordingly. Additionally, the
Polyad cost spreadsheet has a fuel usage of "zero" for all conditions. This was a simplifying
assumption: a more accurate representation would be 48,000 Btu/hr at 15,000 cfm.
These two errors actually tend to bias the total cost calculations in different directions, and
therefore nearly cancel each other out, in terms of final cost. The incorrect and corrected values for
a range of concentrations, and input mass rates (in tons per year) are shown in Table 1.
44
3040 Cornwall,s Road • Pest Office Box *2',9
-------
Table 1. Corrected Cost/Ton Values for the Polyad System.
Input
mass
400 TPY
400 TPY
100 TPY
100 TPY
20 TPY
20 TPY
Correct
Incorrect
Correct
Incorrect
Correct
Incorrect
Inlet concentration, ppm
50
3,473*
3,702
4,622
4,853
8,945
9,191
100
1,998
2,113
2,771
2,889
6,946
7,079
150
1,432
1,512
2,246
2,322
6,196
6,290
200
1,156
1,213
1,967
2,027
5,802
5,878
300
844
883
1,663
1,705
5,395
5,451
500
613
637
1,389
1,416
5,059
5,101
700
522
539
1,261
1,218
4,912
4,947
* Cost ($) per ton of styrene removed.
2) Durr rotary concentrator system - Cost and fuel usage data for the Durr rotary
concentrator were received very near the end of the. original styrene controls assessment project.
I had time to accurately model accurate equipment costs for the Durr rotary concentrator, but I did
not have time to accurately model fuel usage. (The most accurate model of fuel usage for the
system would be based on basic principles of combustion and heating.) The fuel usage calculations
generally over-estimated fuel usage. Knowing that the fuel usage numbers were probably
inaccurate, I left out the fuel cost from the final Total Annualized Cost calculation.
Since fuel cost was actually removed from the Total Annualized Cost calculation, the cost
spreadsheet for the Durr rotary concentrator actually underestimates cost slightly. The incorrect and
corrected values are shown in Table 2.
Table 2. Corrected Cost/Ton Values for the Durr Rotary Concentrator System.
Input
mass
400 TPY
400 TPY
100 TPY
100 TPY
20 TPY
20 TPY
Correct
Incorrect
Correct
Incorrect
Correct
Incorrect
Inlet concentration, ppm
50
3,494*
3,482
4,493
3,945
6,569
6,022
100
1,870
1,870
2,404
2,213
4,563
4,373
150
1,352
1,280
1,721
1,649
3,898
3,827
200
998
986
1,382
1,371
3,567
3,555
300
696
696
1,094
1,094
3,283
3,283
500
469
469
875
875
3,067
3,067
700
372
372
781
781
2,974
2,974
Cost ($) per ton of styrene removed.
45
-------
3) Figure 5-5, "Cost curves for a large plant (400 tons per year inlet)" in
EPA-600/R-96-109 has cost curves for three control technologies plotted on a right-hand axis. ThiS
right-hand axis is incorrectly scaled with a minimum of negative $l,000/ton. The affected
technologies are the EC&C fluidized-bed preconcentrator, the Durr rotary concentrator, and the
VOC condenser: If these technologies are plotted with a minimum cost of $0/ton, similar to other
technologies in Figure 5-5, the resulting curves are somewhat altered.
I have attached a revised version of Figure 5-5. The new figure contains revised curves as
they would appear, assuming the EC&C preconcentrator is desorbed into a thermal oxidizer. The
version of Figure 5-5 that appears in EPA-600/R-96-109 is also attached, with the notation
"ORIGINAL (INCORRECT)".
I have included a diskette with (revised) cost spreadsheets. If you have any questions, please
call me at 541-6016.
46
-------
246,000
c
o
•a
a>
If
el
8*:
Ł *•
>. ii
*
j^
3
a>
a.
4->
w
o
o
10.000
9,000
8,000
7.000 -
6,000
5,000 -
4,000 -
3,000 -
2,000
1,000 -
123.000
Flow rate.cfm (1 cfm = 0.0283 m3/min)
61,500 41,000 30,750 24,600
20,500
17.600
MIAB
• - • Polyad (w/oxidation)
1 ' Catalytic oxidizer (95% H.R. below 100 ppm)
Thermal oxidizer (95% H.R. below 100 ppm)
Biofiltralion
Thermatrix PADRE
— —Durr rotary concentrator
VOC condenser
— • EC&C fluidized-bed preconcentrator (w/oxidation)
100
200
300 400
Concentration (ppm)
500
600
700
Figure 5-5. Cost curves for a large plant (400 tons per year inlet).
-------
10.000
9,000
o
•
o
If
el
2*:
2 *"
0)
a
4-*
M
O
O
8,000
7,000 -
6,000
5,000
4,000
3,000
2,000
1.000
246,000
123 000
Flow rate.cfm (1 cfm = 0.0283 m3/min)
61,500 41,000 30,750 24,600
20.500
17,600
—MIAB
• Polyad (w/oxidation)
—Catalytic oxidizer (95% H.R. below 100 ppm)
• — Thermal oxidizer (95% H.R. below 100 ppm)
- - Biofiltration
• - Thermatrix PADRE
—Rotary concentrator
- - - VOC condenser
• EC&C fluidized-bed preconcentrator
200
300 400
Concentration (ppm)
500
600
700
Figure 5-5. Cost curves for a large plant (400 tons per year Inlet). ORIGINAL (INCORRECT)
-------
TECHNICAL REPORT DATA
(Pleate read lnaaiftlont on the mene before compl
i. REPORT NO.
EPA-600/R-96-136
4. TITLE AND SUBTITLE
Addendum to Assessment of Styrene Emission
Controls for FRP/C and Boat Building Industries
PB97-121156
" I
6. REPORT DATE
November 1996
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Emery J. Kong, Mark A. Banner, and Sonji L. Turner
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Research Triangle Institute
P. O. Box 12194
Research Triangle Park, North Carolina
10. PROGRAM ELEMENT NO.
27711
11. CONTRACT/GRANT NO.
68-D1-0118, Task 192
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Addendum; 8-10/96
14. SPONSORING AGENCY CODE
EPA/600/13
IB. SUPPLEMENTARY NOTES APPCD project officer is Norman Kaplan, Mail Drop 4, 919/541-
2556. This is an addendum to report EPA-600/R-96-109 (NTIS PB97-104640), Sep-
tember 1996.
i6. ABSTRACT The report is an addendum to a 1996 report. Assessment of Styrene Emis-
sion Controls for FRP/C and Boat Building Industries. It presents additional evalua-
tion of the biological treatment of Styrene emissions, Dow Chemical Company's Sor-
bathene solvent vapor recovery system. Occupational Safety and Health Administra-
tion regulations, and other policies that affect the fiber reinforced plastics/compos-
ites (FRP/C) and boat building industries, and secondary, pollution and natural gas
usage resulting from various emission control options.^ .. - ' ^
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution
Styrene Resins
Emission
Boats
Moldings
Fiberglass Reinforced
Plastics
Biology
Solvents
Natural Gas
Pollution Control
Stationary Sources
Boatbuilding
Biological Treatment
13B
11A.11J
14G
13 J
11G
11D
11K
21D
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
57
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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