(351c) CFD Modeling of Steam Gasification of Biomass in a Fluidized Bed
Gasification has been identified as an energy-efficient, environmentally-friendly and economically-feasible technology to partially oxidize biomass into a gaseous mixture of syngas consisting of H2, CO, CH4 and CO2. High-quality syngas can be further used to catalytically synthesize liquid fuels and produce hydrogen. The gasification of biomass in a fluidized bed using steam can produce hydrogen-rich syngas, which is essential for the further catalytic synthesis of liquid fuel from the syngas. Biomass gasification involves complicated reaction pathways, reactive gas-particle behavior, and comminution of solid biomass particles. A computational fluid dynamics (CFD) model with a high order turbulence closure is developed to analyze the behavior of multiple-phase, reactive gas-particle flow during steam gasification of biomass in a fluidized bed gasifier. A commercial Fluent CFD software package is used as a basis for the computational model. Advanced computer visualization techniques are used to observe the patterns of the gas-particle flow and comminution of solid biomass particles in the gasifier. The experimental data are used to validate the CFD model. The effects of gasifier configuration, temperature, steam/biomass ratio, biomass/bed material ratio, biomass loading rate and biomass particle size on the yield and composition of syngas are analyzed using the CFD model.