Investigation and demonstration of dry carbon-based sorbent injection for mercury control. Quarterly technical report, October 1--December 31, 1996

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The U.S. Department of Energy (DOE) has issued Public Service Company of Colorado (PSCo) a cost sharing contract to evaluate carbon-based sorbents for mercury control on a 600 acfm laboratory scale particulate control module (PCM). The PCM can simulate an electrostatic precipitator, a pulse-jet fabric filter, and a reverse air fabric filter and uses actual flue gas from an operating coal-fired power plant. Up to 3 different dry carbon-based sorbents will be tested to determine the mercury removal capability in the different configurations. The project is currently in the fifth quarter of an eight quarter Phase I project. The PCM has been fabricated and mercury removal testing with the ESP configuration has been completed. Original plans included the use on an on-line meercury analyzer to collect the test data. However, due to very low baseline mercury concentration, on-line measurement did not provide accurate data. The project has continued using a modified MESA method grab sample technique to determine inlet and outlet mercury concentrations. A major concern during sorbent evaluations has been the natural ability of the flyash at the test site to remove mercury. This has made determination of sorbent only mercury removal difficult. Overall vapor-phase mercury removals of 15 to 70% have been obtained but this includes mercury removals in the range of 30% by the flyash. It is believed that a maximum of approximately 40% removal due to the sorbent only has been obtained. A number of test and sampling modifications are in progress to increase the data confidence and many questions remain. Startup of the pulse jet configuration began in early November but results of this testing are not available at this time. The project team has decided to proceed with pulse jet testing using flue gas that does not contain significant flyash quantities to further investigate the sorbent only mercury removal.