United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-94/211 January 1995
EPA Project Summary
Evaluation of a Liquid Scrubber
System for Styrene Removal
Larry Felix, Randy Merritt, and Ashley Williamson
Manufacturing processes that involve
the spraying of styrene-based resins
have been identified as a possible sig-
nificant source of volatile organic com-
pound emissions that may affect hu-
man health and contribute to the ozone
non-attainment problem.Until recently,
no known cost-effective technology has
been demonstrated toontrol such emis-
sions of styrene. Now, several pro-
cesses have been developed to control
styrene emissions, and a short-term
field evaluation was planned to charac-
terize the styrene removal efficeincy of
a pilot-scale version of a liquid chemi-
cal scrubbing process. This test was
carried out at a facility (Eljer Plumb-
ingware in Wilson, NC) that manufac-
tures polyester bathtubs and shower
stalls by spraying styrene-based res-
ins onto molds in vented, open spray
booths. A side stream of air exhausted
from one of the spray booths in the gel
coating part of the process was used
for the test.
In this study the syrene removal effi-
ciency of a pi lot-scale version of the
QUAD Chemtact™ scrubber was quan-
tified by continuously measuring the
toatl hydrocarbon (TCH) content of
spray booth exhaust air entering and
exiting the device with THC analyzers
and, for some tests, by collecting EPA
Method 18 samples (adsorption tube
procedure) at the inlet and exit of the
device. Average styren removal efficien-
cies approached but were never >55%.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The report describes an evaluation of
the QUAD Chemtact™ chemical scrubber
for controlling styrene emissions at Eljer
Manufacturing in Wilson, NC. The Eljer
facility manufactures shower stalls and
bathtubs by spraying styrene-based res-
ins onto molds in vented, open spray
booths. Approximately 200 of these types
of facilities operate presently in the U.S.
The manufacturing process consists mainly
of four stages. Stage 1 is the gel coat
application. The gel coat contains styrene,
polyester resin, and pigment. In Stage 2,
styrene and polyester resin are mixed with
inert fillers and sprayed onto a previously
prepared mold using a spray gun equipped
with an attachment to add chopped fiber-
glass. Stage 3 includes the addition of fire
retardant fillers and precut chipboard and
corrugated paper used as structural sup-
ports. In Stage 4, the shower stall or bath-
tub is "pulled" or separated from the mold.
Test Configuration
Manufacturing processes that involve
the spraying of styrene- based resins have
been identified as a possible significant
source of volatile organic compound (VOC)
emissions that may affect human health
and contribute to the ozone non-attain-
ment problem. The mobile pilot unit used
for this test was configured to treat ap-
proximately 100 cfm (2.8 m3/min) of the
air exhaust from a gelcoat spraybooth.
The pilot unit consisted of three reaction
-------
chambers interconnected using plyvinyl
chloride pipe. The QUAD Chemtact™ pro-
cess removes styrene by spraying fine
droplets (a mist) of diluted chemical solu-
tion into a styrene contaminated air stream.
The manufacturer claims that the mist pro-
vides enhanced chemical reactivity and
provides a large surface area where gas-
liquid phase reactions take place that re-
sult in the removal of gaseous contami-
nants. Each reaction chamber was fed by
a separate chemical metering pump so
that a contaminated air stream could be
treated with up to three different chemical
solutions as it passed through the device.
The styrene is apparently oxidized and
absorbed into the scrubber liquor which is
continuously collected and exhausted
through the chamber drain. The treated
air is then exhausted tangentially through
the bottom of the reaction chamber.
Evaluation Results
Styrene removal efficiencies were de-
termined by measuring the inlet and outlet
concentration of the test unit using total
hydrocarbon (THC) analyzers with flame
ionization detectors (FIDs) and charcoal
adsorption tubes (EPA method 18 and
NIOSH method 1501). The liquid scrubber
did not achieve styrene removable effi-
ciencies >55%, although a number of ad-
ditives were tried,including sodium hy-
pochlorite, ethylene glycol, sulfuric acid,
methyl ethyl ketone peroxide, hydrogen
peroxide, and water. The tests were per-
formed on 3 days (6/22/93 through 6/247
93). During the 3 days, 25 separate test
conditions were completed. Costs associ-
ated with installing this technology at a
source of styrene emissions were not ad-
dressed due to the failure of the manufac-
turer to supply any related information.
Table 1 contains the inlet and outlet sty-
rene levels and styrene removal efficiency
for each test conditions.
In addition to the evaluation of the liq-
uid chemical scrubbing process, it was
possible to quantify styrene emissions in
the spray booth exhaust to which the
chemical scrubber was connected. These
analyses revealed that styrene was the
only Volatile Organic Compound (VOC)
with measurable concentrations detected.
Section 2 of the full report contains a
detailed description of the facility and sam-
pling locations, the liquid chemical scrub-
bing device, experimental apparatus, and
experimental methods and procedures.
Data, results, and discussion are in Sec-
tion 3. Section 4 contains the summary
and conclusions. The quality assurance
and quality control measures taken during
this evaluation as well as the results of
these measures are in Appendix B.
Samples of spent scrubber liquid were
obtained from Reaction Chambers 1 and
2 on June 23 and from Reaction Cham-
bers 1,2, and 3 on June 24. On June 23,
only water was injected into Reaction
Chamber 3, so no liquid sample was taken.
In addition, a sample of the process water
used to dilute the chemicals used for scrub-
bing was obtained on June 24. All liquid
samples were preserved in 250 ml glass
sample bottles with Teflon-sealed caps. It
was originally intended to obtain more
scrubber liquid samples. Unfortunately,
because so many test conditions were
tried, it was difficult to isolate a set of
operating conditions (where reasonable
styrene removal was obtained) that per-
sisted for a long enough period to obtain
a set of scrubber samples that were not
contaminated by additives from a previ-
ous test condition.
Table 2 gives the results of the analy-
ses carried out on the samples. The table
shows that styrene was detected in only
the sample from Reactor Chamber 1 on
June 24. Considering that the liquid scrub-
ber styrene removal efficiency was never
>55% during the time these samples were
taken, it is surprising that styrene was
detected in only one sample.
Table 1. Inlet and Outlet Styrene Level and Efficiency of Styrene Removal for Each Test Condition
(6/23/93)
Inlet condition
Inlet styrene, ppm
Outlet styrene, ppm
Efficiency %
1
2
3
4
5
6
7
8
9
10
11
12
13
74.8
82.3
75.6
78.8
80.2
109.9
86.9
95.1
109.0
91.8
85.4
97.3
105.9
41.4
37.7
39.0
40.8
41.2
55.0
41.0
55.1
60.2
52.9
49.9
51.1
48.3
44.7
54.3
48.3
48.1
48.5
50.0
52.8
41.2
44.8
42.3
41.5
47.4
54.5
Table 2. Results of Analyses Carried Out on Scrubber Liquid Samples and a Process Water Sample
Concentration Detection limit
Date Time
6/23 1340
6/24 1040
6/24 1015
Origin
Reaction chamber #1
Reaction chamber #2
Reaction chamber #1
Reaction chamber #2
Reaction chamber #3
Process water
Compound
Chloroform
Acetone
Chloroform
Acetone
Carbon disulfide
2-butanone
Chloroform
Styrene
Acetone
2-Butanone
Chloroform
Acetone
Chloroform
Chloroform
(W/l)
23300
709
39400
1910
104
534000
230
1022
2440
367
1.65
7.41
7.31
55
Bromodichloromethane 12.2
(W/l)
410
364
41
728
280'
1460
82
141
7.28
14.6
0.82
7.28
0.82
0.82
2.37
Conservative estimate of detection limit based on previous mesurements of similar water samples.
-------
L. Felix, R. Merritt, and A. Williamson are with Southern Research Institute, P. O. Box
55305, Birmingham, AL 35255-5305.
Bobby E. Daniel is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of a Liquid Chemical Scrubber System for
Styrene Removal," (Order No. PB95-XXX XXX/AS; Cost: $XX.XX; subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-94/211
------- |