A SHRINKING MODEL FOR COMBUSTION/GASIFICATION OF CHAR BASED ON TRANSPORT AND REACTION TIME SCALES

B. Peters, A. Džiugys, R. Navakas

Abstract


The objective of this contribution is to introduce a shrinking model for gasification of char formed by pyrolysis of biomass or coal. The model describing gasification of a charred particle is based on one-dimensional and transient differential conservation equations for mass, momentum, species and energy. Shrinkage is estimated by a physically based approach of the Thiele modulus or second Damköhler number. It represents a ratio of diffusion time to reaction time and primarily allows distinguishing between a reacting and shrinking core behaviour. Thus, this approach does not require any empirical correlations and is employed to a reacting bed of solid particles. Within the reacting core domain, depleted solid material increases porosity of the solid matrix, while the shrinking core behaviour contributes to a recessing volume.

DOI: http://dx.doi.org/10.5755/j01.mech.18.2.1564


Keywords


thermal conversion; solid fuel; packed bed; model

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Print ISSN: 1392-1207
Online ISSN: 2029-6983