COMPARISON OF METALLIC vs. MEMBRANE BASED WET ESP TECHNOLOGY FOR PM2.5, SO{sub}3 MIST AND MERCURY CONTROL AT A COAL-FIRED POWER PLANT

摘要

Several coal-fired utilities have experienced increased SO{sub}3 emissions from their existing Wet FGD Scrubbers, especially after installing an SCR for NO{sub}x Control. The SO{sub}3 goes largely uncollected through the Wet Scrubber appearing as a dense plume at the FGD stack. Sub micron SO{sub}3 (H{sub}2SO{sub}4 mist) is extremely difficult to remove with conventional technologies, however, Wet Electrostatic Precipitators can readily collect acid aerosol and fine particulate due to greater corona power and virtually no reentrainment. The historical limitations on Wet Precipitators have been their high cost because of stainless steel metal used in their manufacture. Ohio U/ SEI/CRCAT have developed a new membrane based, Wet ESP with dramatically reduced cost and weight compared to metallic wet ESPs. Cleaning of the corrosion resistant fabric membranes, is facilitated by capilliary action between the fibers, providing even water distribution, & continuous flushing removes collected material without spraying, so the entire precipitator remains on line. DOE's National Energy Technology Laboratory has awarded SEI/CRAT and Ohio University a grant to compare metallic and membrane based wet ESP technology in a pilot unit at Penn Power's Bruce Mansfield Plant in Shippingport, Pa. This paper will present the work & results to date. Phase 1 will establish baseline performance with the existing metallic wet ESP. Previous test results demonstrated 97% removal of PM2.5 and SO{sub}3 mist. Upward gas velocity from 12 ft/sec to 20s ft/sec will be tested. Additionally, longevity and reliability of the membrane material over time will be measured.