New Pyrolysis Model for Biomass Particles in a Thermally Thick Regime

Abstract

In order to get a deep understanding of biomass pyrolysis and gasification with particle size ranging from several millimeters to centimeters, detailed modeling of thermochemical conversion of thermally thick particles is required. In this paper, a new pyrolysis model for a large biomass particle is established, and the porous particle is modeled with two systems. In the continuous system, a uniform multiphase CFD algorithm is implemented to resolve both internal and external flow fields, and the solid temperature is solved by considering heat conduction, heat convection, and radiation. In the discrete system, the large particle is regarded as a porous media and discretized into a cluster of small virtual particles which are used to model the devolatilization and particle shrinkage. The evolutions of porosity and internal specific surface area during pyrolysis are also taken into account. The proposed model is first validated with the experiments in the literature, and good agreements have been obtained. ...