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PILOT PLANT STUDY OF CONVERSION OF COAL TO LOW SULFUR FUEL
Citation:
Fleming, D. AND R. Smith. PILOT PLANT STUDY OF CONVERSION OF COAL TO LOW SULFUR FUEL. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-77/206.
Description:
The report gives results of a program to develop, on bench and pilot scales, operating conditions for the key step in the IGT process to desulfurize coal by thermal and chemical treatment. This process, to date, uses the 'sulfur-getter' concept. (A sulfur-getter is a material that has a greater chemical affinity for sulfur than coal has.) Lime was the sulfur-getter for this program. In Phase I, a coal/lime mixture was experimentally treated at atmospheric pressure with a reducing gas in a heated, fluidized bed reactor, which could treat up to 200 lb/hr of mixture to 1200 F. The coal was Illinois No. 6, containing about 3% sulfur. Initial work resulted in the discovery that less sulfur was removed than expected. Two factors were believed responsible: the coal heat-up rate in the fluidized bed was nearly instantaneous, which appeared to cause organic sulfur fixation; and the coal showed signs of weathering (therefore, the total sulfur content was not readily available for hydrogen treatment). Phase II redirected the program to the operation of smaller scale units featuring: controlled heat-up rates, an increased number of tests over a broader range of conditions (with savings in time and manpower), and coal samples from several U.S. mines. A coal/lime mixture was treated with hydrogen, in batch reactors, to 1500 F. Tests indicated that lime treatment does not capture all sulfur released from the coal.