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 ------- |