Combustion characterization of the blend of plant coal and recovered coal fines. Final technical report, September 1, 1991--August 31, 1992

摘要

The overall objective of this proposed research program was to determine the combustion characteristics of the blend derived from mixing a plant coal and recovered and clean coal fines from the pond. During this study, one plant coal and three blend samples were prepared as 100% plant coal, 90% plant coal/10% fines, 85% plant coal/15% fines, and 80% plant coal /20% fines with a particle size distribution of 70% passing through (minus)200 mesh size. The plant coal and recovered coal fines were obtained from the Randolph Preparation Plant of Peabody Coal Co., Marissa, IL. These samples' combustion behavior will be examined in two different furnaces at Penn State University, i.e., a down-fired furnace and a drop-tube furnace. The down-fired furnace was used mainly to measure the emissions and ash deposition study, while the drop tube furnace was used to determine burning profile, combustion efficiency, etc. The burning profile of the plant coal and the three blends was determined in a thermogravimetric analyzer. Results indicated slower burning of the blends due to low volatile matter and oxidized coal particles. Combustion emissions of these samples were determined in the down-fired combustor, while relative ignition temperatures were determined in the drop tube furnace. Chemical composition of ashes were analyzed to establish a correlation with their respective ash fusion temperatures. Overall study of these samples suggested that the blended samples had combustion properties similar to the original plant coal. In other words, flames were stable under identical firing rates of approximately 200,000 Btu's/hr and 25% excess air. CO, NO(sub x), and SO(sub x), were similar to each other and within the experimental error. Combustion efficiency of 99(sup +)% was achievable. Ash chemical analysis of each sample revealed that slagging and fouling should not be different from each other.