Tests were performed at the Energy & Environmental Research Center (EERC) to evaluate selected sorbents (Norit DARCO 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{sup}3 (dry flue gas, 3% O{sub}2) total mercury with 80%-90% elemental vapor. Increasing injection of DARCO FGD carbon promoted mercury capture in the Advanced Hybrid filter, and mercury removal by DARCO 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 FGD carbon. Overall mercury removal of over 70% was achieved at 1.2 lb/Macf DARCO 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°F flue gas environment, reaching 48% mercury collection at 2.2 lb/Macf injection.
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