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Understanding Coal Gasification

AUTHOR: Alice Kristiansen
DATE: March 1996

Recent literature mainly post 1990, on the fundamental processes and the mechanisms of the coal gasification is reviewed. Six main sections cover fundamental reactions, pyrolysis, high temperature gasification, gasification catalysts and pollutant information.

The section on fundamental reactions reviews the mechanisms and the intrinsic kinetics of the fundamental gasification reactions, and the various mechanistic and kinetic models suggested.

The section of pyrolysis covers the physical and chemical mechanisms, modelling, weight loss behavior, volatile products, and char. High temperature gasification is reviewed in terms of char reactivity and parameters such as particle temperature, partial and total pressure, gasifying atmosphere, coal rank, surface area and porosity. Furthermore, the structural models for char gasification are reviewed in this section. The section on gasification catalysts reviews the inherent catalysts for oxidative gasification and their influence on coal reactivity. Recent developments in the behavior of sulfur, nitrogen, and trace elements, during gasification are reviewed in the last main section.

It is concluded that while better understanding of the process may lead to development of empirical models for specific sets of conditions, the sheer complexity of the process makes it unlikely that there can be a fundamental, universal model of all coal gasification processes. Directions for further research are identified.