The Mechanisms of Spinel/Solid Solution Formation and Wear in Gasification High Chrome Oxide Refractories Caused By Carbon Feedstock Impurities

Abstract

Gasification is a term used to describe the process of converting high carbon materials (such as coal and petcoke) into H2 and CO gases used in the production of power or as a feedstock material in chemical production. High temperature slagging gasifiers are operated between 1325-1575oC; a temperature range that oxidizes, transforms, and/or melts organo-metallic and mineral impurities in the carbon source; forming molten particles that coalesce into slag. By-products from the gasification of a carbon feedstock constitute about one wt pct of petcoke to about 10 wt pct or more for coal. To protect the gasification chamber from the severe service environment, they are lined with high chrome oxide refractories, a material which slowly interacts with the slag, and which need to be replaced every 6-36 months. Longer and predictable service life of the refractory liner is desired. Refractory wear is caused by interactions between the slag and refractory, leading to chemical dissolution or spalling (chemical or structural) of the liner. The chemical and physical nature of the wear, along with a thermodynamic study of process are discussed; with emphasis on the role of slag Al, Mg, Fe, and V interactions with refractory brick to form spinel/solid solution structures.