Refractories for Coal Gasification. The State-of-the-Art in the U.S.

Abstract

The state-of-the-art of refractories for coal gasification is reviewed. Both dry ash and slagging coal gasification process conditions and materials are discussed. Among the potential failure mechanisms to be dealt with include: (1) corrosion and erosion due to molten coal slag, iron, or both; (2) alkali attack; (3) carbon monoxide induced disintegration; (4) reduction of silica by H₂; (5) iron oxide bursting; (6) steam related reactions; (7) thermoelastic stresses; and (8) particulate erosion. Results from pilot plant exposures and a variety of DOE-sponsored laboratory experiments indicate that dense fireclay castables containing approximately 50% alumina and having a low iron content are the preferred materials for use in dry ash gasifiers (temperature <1200°C). In slagging gasifiers operating at intermediate temperatures (1200–1600°C), coal slag corrosion/erosion may be minimized through the judicious selection of materials (high density, high-chromia refractories), coals, fluxes, and process temperatures, and through careful design of water-cooled linings. For slagging gasifiers operating in excess of 1600°C, the slagging boiler design consisting of a thin sacrificial refractory lining on water-cooling tubes is preferred. Current DOE-sponsored research and development programs are reviewed and areas for future research are identified.