Comparison of Solid Wastes from Coal Combustion and Pilot Coal-Gasification Plants. Final Report

摘要

Comparisons of the physical and chemical properties of solid wastes from coal combustion and gasification processes should assist in deciding whether gasification solid wastes can be utilized or disposed of in the same manner as combustion solid wastes. In this study, solid wastes from a pilot scale (150 Mg/d) entrained flow coal gasifier (Combustion Engineering) were compared with solid wastes from two conventional coal-fired power plants, a pulverized coal boiler, and a cyclone boiler. All three facilities were firing a common feedstock, Pittsburgh seam coal from West Virginia. Solid wastes were characterized with respect to composition, mineralogy, selected physical properties (e.g., morphology, particle size, specific surface area, hydraulic conductivity) and leaching behavior (batch and column extraction). Slag from the gasifier and slag from the cyclone boiler were physically and chemically similar, both wastes exhibiting low leachability and rates of leaching of inorganic toxic constituents. In contrast, combustion fly ash exhibited relatively high leachability of certain toxic elements (e.g., Cd). The results of this study generally suggest that entrained flow coal gasification, with char recycle and by-product elemental sulfur recovery, should not require solid waste management practices different from those currently used for coal combustion solid wastes. The absence of a fly ash-like waste and production of sulfur in a potentially marketable form appear to offer environmental advantages over conventional coal combustion. (ERA citation 08:022955)