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A single-particle char gasification model



A model is developed for the gasification of a single-char particle in an environment of water, hydrogen, carbon dioxide, carbon monoxide and methane, existing in the gasification zone of a reactor. The model, consisting of the mass and energy conservation equations, together with the Stefan-Maxwell relations includes the intraparticle effects and the change in internal surface area. It is found that the intraparticle effects and the surface area effects are significant and hence cannot be neglected, and the situation becomes more acute with increasing particle size and high temperatures. Comparisons with other models and existing empirical relations show that the model agrees well when diffusional effects are minimal, but at higher temperature and large pariticle size there is a significant difference. The model may be used to discriminate among various idealized models such as the homogeneous and the shrinking core model. The conyective terms in the Stefan-Maxwell relations have negligible influence. The analysis can be directly used in the modeling studies of gasification reactors and will be so applied in a later paper.

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