Impact of Coal Properties on Coal Combustion By-product Quality: Examples from a Kentucky Power Plant
Institution
University of Kentucky
Faculty Advisor/ Mentor
James Hower
Abstract
Coal properties impact the quality of coal combustion by-products. Tracking impacts can often be difficult, particularly in the eastern United States, because utilities use blended coal feeds to meet their quality specifications. To circumvent this problem, we made arrangements for a single seam/single mine coal to be burned at a 200 MW boiler. The feed coal is a medium sulfur, high volatile A bituminous Fire Clay seam from Knox County, eastern Kentucky. The coal was mined over a two-week period in order to supply the utility with sufficient fuel for a two-day run. The coal was sampled as a whole channel and benches at the mine, as the shipped coal at the power plant, and as a pulverized coal prior to injection into the boiler. The pulverizer reject, commonly called “pyrites” by utilities, was also sampled. Fly ash was sampled from the economizers, two rows of mechanical hoppers, and four rows of electrostatic precipitator hoppers. Bottom ash also was sampled. The plant is not equipped for flue-gas desulfurization. Analyses on the mine and plant samples include, as appropriate, proximate/ultimate/ sulfur forms/heating value, major oxides, trace elements, x-ray diffraction, and petrographic composition. The influence of coal properties on fly ash properties in this isolated case will be discussed. While specially-arranged burns, such as for this study, are not representative of the reality of coal purchasing and coal combustion in the eastern US, attempts to follow a single coal through the process can be instructive for the purposes of understanding the origin and fate of trace elements in combustion.
Impact of Coal Properties on Coal Combustion By-product Quality: Examples from a Kentucky Power Plant
Coal properties impact the quality of coal combustion by-products. Tracking impacts can often be difficult, particularly in the eastern United States, because utilities use blended coal feeds to meet their quality specifications. To circumvent this problem, we made arrangements for a single seam/single mine coal to be burned at a 200 MW boiler. The feed coal is a medium sulfur, high volatile A bituminous Fire Clay seam from Knox County, eastern Kentucky. The coal was mined over a two-week period in order to supply the utility with sufficient fuel for a two-day run. The coal was sampled as a whole channel and benches at the mine, as the shipped coal at the power plant, and as a pulverized coal prior to injection into the boiler. The pulverizer reject, commonly called “pyrites” by utilities, was also sampled. Fly ash was sampled from the economizers, two rows of mechanical hoppers, and four rows of electrostatic precipitator hoppers. Bottom ash also was sampled. The plant is not equipped for flue-gas desulfurization. Analyses on the mine and plant samples include, as appropriate, proximate/ultimate/ sulfur forms/heating value, major oxides, trace elements, x-ray diffraction, and petrographic composition. The influence of coal properties on fly ash properties in this isolated case will be discussed. While specially-arranged burns, such as for this study, are not representative of the reality of coal purchasing and coal combustion in the eastern US, attempts to follow a single coal through the process can be instructive for the purposes of understanding the origin and fate of trace elements in combustion.