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Measurement of Total Site Mercury Emissions from a Chlor-Alkali Plant Using Ultraviolet Differential Optical Absorption Spectroscopy and Cell Room Roof-Vent Monitoring
THOMA, E. D., C. SECREST, E. S. HALL, D. JONES, R. C. SHORES, M. MODRAK, R. HASHMONAY, AND P. Norwood. Measurement of Total Site Mercury Emissions from a Chlor-Alkali Plant Using Ultraviolet Differential Optical Absorption Spectroscopy and Cell Room Roof-Vent Monitoring. ATMOSPHERIC ENVIRONMENT. Elsevier Science, New York, NY, 43(3):753-757, (2009).
Mercury-cell chlor-alkali plants can emit significant quantities of fugitive elemental mercury vapor to the air as part of production operations and maintenance activities. In the fall of 2006, the U.S. Environmental Protection Agency (EPA) conducted a measurement project at a chlor-alkali facility in the southeastern United States to determine if whole-site fugitive mercury emissions were on the order of historic assumptions of 1,300 g/day. External monitoring systems were set up outside and downwind of the cell room building and ancillary processes to estimate emissions during a 53-day monitoring campaign. EPA area source emission measurement method OTM-10 was used in conjunction with three open-path ultraviolet differential optical absorption spectroscopy instruments to provide mercury flux data for the site. This paper describes these optical remote sensing measurements and compares the results with mercury emission data from the cell room roof vent monitoring system simultaneously acquired by the facility. The 24-hour extrapolated mercury emission rate estimates determined by the two monitoring approaches are shown to be similar with overall averages in the 400 g/day range with maximum values around 1,200 g/day. Results from the optical remote sensing measurements, which include both cell room emissions and potential fugitive sources outside the cell room, are shown to be approximately 10% higher than cell room monitoring results indicating that fugitive emissions from outside the cell room produce a small but measurable effect for this site. Data from this measurement campaign are shown to be similar to overall levels found in previous studies in Europe and the U.S.