Labadie Coal Blending Study

Client Union Electric Company P.O. Box 149 St. Louis, Missouri 63166 Completion Date May, 1994

Project Description
Union Electric engaged Energy Associates to study the coal handling and storage facilities at the Labadie Plant. This study investigated improvements to the plant's coal stacking and reclaim systems to solve coal washthrough and blending problems.

The original intent of the Labadie blending system was to improve SO2 emission control while minimizing the cost of low sulfur coal. The blending system stockpiled and reclaimed low sulfur coal from an area that is separate from the two radial stackers. The radial stackers continued to handle high sulfur coal. The blending system was designed to proportion reclaimed coal from the low sulfur pile to the high sulfur coal being reclaimed at the same time. The blending system fulfilled its original purpose and provided added operating flexibility for the plant. The Labadie Plant was being converted to fire low sulfur, Powder River Basin (PRB) coals, which are more economical than high quality, low sulfur coal sources. To handle the PRB coals, improvements are necessary for the blending system.

The three primary study objectives are as follows:

• Coal Washthrough: One objective of the study is to identify operating strategies and/or equipment modifications which will eliminate or dramatically reduce the frequency of washthrough events. Coal and water sometimes washes through the slot, filling the reclaim tunnel. Over the years, this problem was controlled by maintaining maximum coal pile heights over the tunnel's slot, especially when heavy rain storms were expected. With heavy rains in 1993, washthroughs become very frequent. A great deal of labor, clean-up and repair expense has been incurred. As a result of the washthroughs, the availability of the blending system decreased.
• Coal Blending Strategy: The second objective of the study is to develop operating strategies/or equipment modifications to store and reclaim both the high and low quality coals on the blending system without developing fires. Due to the lower heating value and lower Hardgrove Index of PRB coals, Labadie's coal mills were the main barrier to achieving full plant output on 100% PRB coal. The plant's operating strategy for overcoming this limitation altered the role of the blending system. A high quality, low sulfur western coal was to be stockpiled on the blending system. This coal would be blended with the lower quality, low sulfur PRB coals reclaimed from the radial stockpiles. About 15% of the 6 million tons per year of coal consumed by Labadie would be handled by the blend system.
• Alternative Blending Strategy: The third objective for the study was to determine whether an alternative blending strategy would be more beneficial compared to the then current plan.