Modeling and analysis of single particle conversion of biomass in a packed bed gasification system

Abstract

The present study focuses on developing a comprehensive one-dimensional spherically symmetrical model for single particle biomass conversion - a precursor for a packed biomass gasification model. Pyrolysis, volatile combustion and char reactions with a range of reacting species and inert environment are considered in the analysis. Flaming and inert pyrolysis are independently validated with experimental results available in the literature. The influence of thermo-physical properties, like density, thermal conductivity and particle size which affect the Biot number, heat flux, and surface to volume ratio of the particle are studied. Superficial activation energy is proposed to normalize the conversion time with data from different sets of experiments to address the effect of temperature by using a corrected time. Particle with Biot number close to unity suggests a departure from d2 law whereas larger size particle shows close dependence on d2 law indicating a typical diffusion dominated process. The model is compared with a broad range of experimental results available in the literature. The prediction of conversion time, temperature profiles, weight loss rate and model results with normalization to physical parameters, suggests that the predictions with such variability are good enough to be used as a robust model for the packed bed gasification or combustion.