Sorbents for removing mercury from flue gases of coal-fired power plants are presently being evaluated due to potential regulation of mercury emissions under Title III of the 1990 Clean Air Act Amendments. Laboratory tests have been con- ducted to evaluate the adsorption charactertstics of potential sorbents and the effects of flue gas constituents on these char- acteristics. This paper presents a theoretical model that com- bines the adsorption charactertstics measured in the lab with mass trarisfer considerations to predict mercury removal by the duct injection process in actual flue gas streams. The model was used to detemine the effect of various sorbent properties on mercury removal when injecting a powdered sorbent up- stream of either an eletrostatic precipitator (ESP) or fabric fil- ter Mercury removal is expected to differ between these con- figurations since the mass transfer conditions are different in an ESP and fabric filter. The model was used to determine when mercury removal is limited by mass transfer and when it is limited by sorbent capacity. This infomiation defines condi- tions when removal can be improved by reducing particle size or increasing sorbent capacity in both cases, removal can be increased by injecting more sorbent.
展开▼
