Mercury capture on fly ash was studied at a coal-fired utility boiler burning a single-mine source high-Hg Appalachian coal. Other elements were also studied incidental to the Hg study. Fly ash was collected through a cross-section of the ash collection system, representing ash captured at different flue gas temperatures. In general, Hg concentration in the fly ash increases with an increase in the fly ash carbon and a decrease in flue gas temperature. The relationship between the latter two parameters and the Hg content was not as well defined as in previous studies where the petrographic forms of the carbon could be isolated.

No abstract

Coal and fly ash samples were collected from a 500-MW unit at a Kentucky power plant, with the objective of studying the distribution of arsenic, mercury, and other trace elements in fly ash. The coal feed was low-sulfur, high volatile A bituminous central West Virginia coal. The plant produced a relatively low-carbon fly ash. In contrast to power plants with high-mercury feed coal, the fly ashes from the lower-mercury feed coal had low mercury values, generally not exceeding 0.01 ppm Hg. Mercury capture by fly ash varies with both the amount and type of carbon 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 potential for catalyst poisoning in the selective catalytic reduction system (in the planning stage at the time 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.

No abstract