Time Variation of Properties of Rosebud Coal Seam (Eastern MT)

摘要

The average time variation of the properties of the Rosebud coal seam (the Western US standard MHD coal) has been determined. Additionally, the effect of a conventional coal-fired power plant's feeding system upon the coal properties has been determined. The variations of the properties, Btu, moisture, ash, total sulfur, and major and selected metal content determined for 695 Rosebud coal tipple samples (representing two year's supply of coal to the Montana Power Company Units I and II at Colstrip, Montana) have been observed to deviate from a minimum of 6.6% to a maximum of 32.2% for moisture and iron, respectively. Grouping the tipple samples into sets of 27, lowers these variations for moisture and iron to +-2.5% and 13.2%, respectively. Property averages for the 695 tipple samples (representing approx. = 6 x 10 exp 6 tons of Rosebud coal) represent the most reliable characterization of the Rosebud coal seam to date. The analysis of Rosebud coal samples collected at prescribed sites along the MPC coal feeding system reveals that the variations in properties are not significantly reduced by the preparation system. However, the MPC air classification-Bowl Mill system appears to be effective in reducing the pyrite and calcite content of the coal prior to injection into the burners. The reduction of these ash components in the coal may have a beneficial effect upon combustion and slag/seed management. (ERA citation 07:013645)