Simulation of char burnout characteristics of biomass/coal blend with a simplified single particle reaction model

Abstract

A single particle reaction model has been developed to study the char burnout characteristics of co-firing of coal and biomass under air and oxy-fuel combustion conditions. Two types of coal/biomass blend, i.e., Brisbane bituminous coal blended with woodchip, and Loy Yang lignite coal blended with woodchip, have been studied. The model is validated with different sets of experiments and CFD simulation from the literature. The effects of biomass fraction, particle size, oxygen level and gas temperature have been investigated. It is found that increasing biomass blending ratio, oxygen concentration, [O2], or the gas temperature, tg, increases char reactivity and conversion rate and reduces char burnout time. The current numerical study demonstrates that comparing to traditional CFD simulation, the proposed single particle reaction model takes much less simulation time and efforts, while able to provide a deep insight into char burnout characteristics in co-combustion process.