Biomass gasification in a downdraft fixed-bed gasifier: Optimization of operating conditions

Abstract

In the present study, a CFD model was developed for the biomass gasification process in a downdraft fixed-bed gasifier. Sugarcane bagasse was used as feedstock in gasification experiments and simulation studies. Several operating parameters, including the velocity and preheating temperature of the inlet air/steam mixture, steam to air ratio (S/A), and biomass moisture content (MC), were investigated to achieve the maximum syngas yield (CO2, H2, CH4, and CO) and conversion efficiency. Results proposed that the syngas yield and conversion efficiency were maximized at S/A of 0.67 and inlet velocity of 20 m/s. In addition, increasing the preheating temperature of air/steam and decreasing the MC of bagasse had positive impacts on the gasification process. The maximum conversion efficiency was 69.14% at the optimum operating conditions. This study offers an advanced tool for the simulation of gasification process that can be used in primary-stage engineering designs.