PILOT-SCALE STUDY OF ADVANCED MERCURY CONTROL TECHNOLOGIES FOR LIGNITE-FIRED POWER PLANT IN A RETROFIT ADVANCED HYBRID~(™) FILTER

摘要

Tests were performed at the Energy & Environmental Research Center (EERC) to evaluate selected sorbents (Norit DARCO~(~R) FGD carbon and EERC regenerated carbon) combined with fuel additives for mercury removal in a 580-MJ/hr coal combustion system equipped with an electrostatic precipitator (ESP) followed by an Advanced Hybrid~(™) filter. Ontario Hydro sampling and continuous mercury monitors were used to measure mercury species concentrations across the control devices when sorbents were injected upstream of the Advanced Hybrid~(™) filter and fuel additives were fed into the furnace with Freedom lignite coal, which generates an average 8 μg/Nm~3 (dry flue gas, 3% O_2) total mercury with 80%-90% elemental vapor. Increasing injection of DARCO~(~R) FGD carbon promoted mercury capture in the Advanced Hybrid~(™) filter, and mercury removal by DARCO~(~R) FGD carbon showed no significant dependence on temperature in the retrofit Advanced Hybrid~(™) filter with Freedom coal combustion flue gas. Both continuous and batch injections were evaluated in the retrofit Advanced Hybrid~(™) filter for mercury emission control. Results indicated that mercury removal typically increased with batch injection. Fuel additives significantly enhanced mercury removal across the retrofit Advanced Hybrid~(™) filter with the DARCO~(~R) FGD carbon. Overall mercury removal of over 70% was achieved at 1.2 lb/Macf DARCO~(~R) FGD carbon batch injection combined with 7.34 lb/Macf NaCL (1.3 lb of CL/ton of coal). EERC regenerated carbon proved encouraging in removing mercury across the retrofit Advanced Hybrid~(™) filter with batch injection in a 300℉ flue gas environment, reaching 48% mercury collection at 2.2 lb/Macf injection.