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FINAL TECHNICAL REPORT September 1, 1987 through November 30, 1988

Project Title:

Principal Investigator: Other Investigators: Project Monitor:

Combustion of Coal-Derived Low-Volatile Fuels in a Slagging Combustor

Dr. William M. Swift, Argonne National Laboratory Mr. F. Gale Teats, Argonne National Laboratory Dr. Mike Lin, CRSC

ABSTRACT

Several projects funded by the Center for Research on Sulfur in Coal (CRSC) have envisioned the pyrolysis or mild gasification of coal as a means for improving the market for high-sulfur Illinois coals. The volatiles would be recovered for their chemical value or upgraded by hydrotreating processes to an acceptable refinery feedstock. The potential economic advantage of this approach over conventional gasification and/or liquefaction processes assumes that the product char can be either gasified to a clean fuel or burned efficiently in industrial and/or utility boilers. The reactivity and combustion properties of a coal and coal-derived solid fuels in a fluidized- .. : .. bed combustor (Argonne National Laboratory) and a thermogravimetric analyzer (Illinois State Geological Survey) have been the subject of a previous study. The current work has investigated the combustion characteristics of a partially devolatilized char in a 2-MW staged slagging combustor located at Argonne National Laboratory (ANL).

The char was produced from a 50-50 blend of high volatile Illinois No. 5 and No.6 coals. Xcel Group Inc. produced the char in a direct-fired rotary kiln by contacting the coal with the hot gases from a substoichiometric burner at temperatures in the range of 375 to 400°C. The resulting char contained approximately 18 wt % volatiles compared to about 37 wt % in the starting coal. The char was pulverized to 80% -200 mesh and fired in the ANL slagging combustor at air preheat temperatures of 500 and 1000°F and overall air-to­fuel stoichiometric ratios in the range of 1.08 to 1.21. Under these conditions, combustion efficiency of the char varied from 91.1 to 95.8%. The results of this work indicate that significantly higher combustion efficiencies could be obtained by further increasing the air-to-fuel stoichiometric ratio.

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