Gasification of char particles in packed beds: analysis and results

Abstract

In this paper a packed bed of char particles is considered for experimental study and analysis. The packed char bed is modelled by extending the single-particle analysis (Dasappa et al., 1994a, Chem. Eng. Sci. 49–2:223–232. Dasappa et al., 1994b, Twenty-fifth Symposium (International) on Combustion, pp. 1619–1628. Dasappa et al., 1998, Twenty-seventh Symposium (International) on Combustion, pp. 1335–1342.). All the reactions related to gasification are introduced into the reaction system as in Dasappa et al. (1998). The propagation of the reaction front into the packed char bed against the air stream is modelled. The results are compared with the experimental data on a model quartz reactor using charcoal. Experimental data of propagation of the reaction front through the packed bed from the present study and of Groeneveld's charcoal gasifier are used for comparison. Using the analysis of Dosanjh et al. 1987 (Combust. Flame 68:131–142), it is shown that heat loss dominates the heat generation at the quench condition. It is also shown that increasing the oxygen fraction in air has resulted in flame front to propagate into the char bed. The critical air mass flux for peak propagation rate in a bed of char is found to be 0.1 kg m−2 s. Copyright © 2001 John Wiley & Sons, Ltd.