Gasification and Combustion of Biomass: Physical Description and Mathematical Modeling

Abstract

Abstract The combustion and gasification of biomass are the major approaches to the utilization of biomass energy. This article discusses the fundamental processes involved in the gasification and combustion of biomass. The focus is on the mathematical description of the various subprocesses encountered in these thermochemical conversion processes, including drying, devolatilization/pyrolysis, char oxidation and gasification, shrinking of biomass, and heat and mass transfer inside the biomass particles. Phenomenological models for the various subprocesses are reviewed for numerical simulations of the thermochemical conversion process of the biomass particles. The models are evaluated by comparing the model results with experimental data under various experimental conditions. The basic thermodynamic properties of biomass, char, tar, and volatile gases are examined. It is shown that due to the large diversity of biomass characteristics, the measurement data out of experiments conducted in different facilities show a large scatter. Corresponding to this large scatter in experimental data, one can notice that there is a large scatter in model approaches, as well as the thermodynamic and chemical kinetic data reported in the literature. Phenomenological models can simulate the various experiments, provided that certain adjustments in the chemical kinetic data have been made. The performance of various submodels and suggested model parameters is demonstrated for various test cases.