文摘
Coal and fly ash samples were collected from a 500-MW unit at a Kentucky power plant, withthe objective of studying the distribution of arsenic, mercury, and other trace elements in flyash. The coal feed was low-sulfur, high volatile A bituminous central West Virginia coal. Theplant produced a relatively low-carbon fly ash. In contrast to power plants with high-mercuryfeed coal, the fly ashes from the lower-mercury feed coal had low mercury values, generally notexceeding 0.01 ppm Hg. Mercury capture by fly ash varies with both the amount and type ofcarbon and the collection temperature; mercury capture is more efficient at lower temperatures.Arsenic in the feed coal and in the flue gas is of concern to the utility, because of the potentialfor catalyst poisoning in the selective catalytic reduction system (in the planning stage at thetime of the sampling). Arsenic is captured in the fly ash, increasing in concentration in the more-distant (from the boiler) reaches of the electrostatic precipitator system.