Variation in Coal Combustion By-Products with Respect to Coal Source

The correlation between coal geochemistry at the mine and at the power plant and in the consequent coal combustion by-products (CCB) is often obscure. Coal shipments arriving at the power plant are often a blend of several coal seams from multiple mines. Multiple suppliers further complicate the "parentage" of the coal blend actually fired into the boiler. Individual shipments may actually be segregated on the stockpile according to the time of arrival, but the lag time between arrival and use, often several months, further limits the ability to trace the source of a coal fired on a particular day. With these complications, the correlation of a single CCB to the source coal is certainly difficult. Trace elements in coal and CCB' s remain a topic of interest. Certain elements, Hg in particular, remain under investigation for air quality issues. Other elements, such as arsenic, may be detrimental to the operation of the next generation of NOx-reduction equipment, poisoning the catalysts used in SCR units. Further understanding of the geology of the coal and the fate of trace elements in coal pulverization and coal combustion is necessary if coal use is to be optimized with respect to engineering and environmental concerns. As an example of the type of study proposed, the CAER had the opportunity to study a single-source coal feed to a southeastern Kentucky power plant. The coal came from a single mine, allowing us to sample the coal at the mine face. The shipment of coal was isolated and then run over a two-day period. Sampling on the second day ensured that the ash was from the burn of the single-source coal. The emphasis in the latter study (Sakulpitakphon et aI., 2000, Energy & Fuels, v.14, p. 727-733; paper emphasizing mine site geology in preparation) was on the mercury distribution on fly ash through the ash collection system. Additional elements, such as Pb and As, are of interest in the same coal. Although few, if any, individual utility boilers rely on a single-seam source of their feed coal, it is possible to isolate single-seam sources. We propose to arrange several single-source burns. In each case, the following would be sampled: . coal in the mine, sampled by lithologic divisions . (if applicable) the preparation plant product . coal shipment to the plant (sampled at the power plant) . pre-pulverizer feed coal . pulverized coal . (if possible) the pulverizer reject . coal combustion by-products. One round of sampling has been arranged with East Kentucky Power Cooperative's Cooper Power Plant. In the latter case, the coal would probably not be beneficiated. Cooper does not utilize flue-gas desulfurization. We have discussed cooperative efforts with Maria Mastalerz, Indiana Geological survey, in which an Indiana mine would provide a single-source to an Indiana power plant. In the latter case, a mine-power plant combination has not yet been identified. The CAER would be responsible for sampling at the mine and, with the assistance of the utility, at the power plant. Petrographic analyses would be performed at the CAER. Splits of all samples will be provided tOe USGS for geochemical analyses. C The proposed budget would support one-month for Jim Hower, summer plus partial school-year support for an undergraduate student (University of Kentucky Department of Geological Sciences), and compensation for sampling supplies, as shown on the attached budget page.