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Show The goals of this task are listed below in order of priority. It is desirable that these goals be achieved simultaneously. • Particulate emissions of less than 0.005 IblMMBtu • Maximum filter clean-side draft loss of 8 inches w.g. at 4 ftlmin at 775°F • Operation with a Filter Face Velocity (FFV) of at least 4 ftlmin at 650°F • Minimum of 80% NOx removal efficiency • Ammonia slip of less than 15 ppm Information gained from demonstration and evaluation will address the following issues: • Confirm filter particulate removal efficiency. • Determine the tubesheet differential pressure (filter draft loss) as a function of face velocity, cleaning cycle characteristics, operating time, and other parameters. • Determine the NOx reduction efficiency as a function of flue gas composition (NOx inlet concentration, NH3 stoichiometry, particulate removal), and flue gas temperature. Of further interest is the determination of the requirements to maintain the catalytic conversion efficiency. Approach: The approach used is to test the Catalytic Filter System with four filter modules on a 100 ACFM (165 m3/hr) slipstream at Richmond Power & Light's Whitewater Valley Station Unit 2, a 66 MWe pulverized coal-fired boiler. CeraMem manufactured the ceramic filter modules and Engelhard applied the NOx reduction catalyst. A slipstream unit was constructed and installed at the Richmond site, taking flue gas off the boiler at the economizer section, processing the gas to remove particulate and NOx, and returning the gas to the air heater. The test system was installed at the site February and March of this year, and operation started immediately upon completion of installation. At this writing, an initial500-hour test has been concluded, in which both particulate removal and NOx reduction were investigated. Preliminary Results: The tubesheet differential pressure (filter draft loss) is considered an essential element to the success and applicability of the catalytic filter to the LEBS Commercial Generating Unit (CGU) design. An excessive tubesheet differential pressure would require excessive fan power to move the flue gas through the system for processing. For the first 500-hour test, the initial tube sheet differential pressure was approximately 16 inches w.g. (FFV=4 ftlmin, T= 650°F). The filter permeance, a parameter inversely proportional to tubesheet differential pressure and independent of filter face velocity and process temperature, decreased through the first 150 hours of operation, as shown in Figure 5. This decrease indicated that the filter tubesheet differential pressure increased at constant process conditions, an effect that is typical of all ceramic particulate filters. This decrease in permeance or increase in tubesheet differential pressure is caused by the smaller particulate (less than 0.511 diameter) becoming permanently lodged in the filter substrate. For all ceramic particulate filters, the filter permeance should stabilize at some point, indicating that essentially the pores that are able to become "plugged" have been, and that the filter is being cleaned efficiently. At this point, the tubesheet differential pressure will remain constant at constant process conditions. In the case of the initial 500-hour test, the tubesheet differential pressure rose to approximately 23-24 inches w.g. (FFV=4, T=650°F) after approximately 200 hours of operation and was stable for the remainder of the test. Upon conclusion of the 500-hour test, the system was opened and the filter modules were inspected. Visual inspection showed that the filters were being cleaned effectively, with no particulate buildup being detected and no plugged channels being found. Subsequent analysis of the catalytic filters indicate that catalyst addition was responsible for approximately 75 % of the tubesheet differential pressure. 1 |