372 / 2018-07-30 17:47:26

Application of coarse grain model used in biomass steam gasification in a fluidized bed

全体主题 > 生物质燃气

Fluidized bed reactors are widely used in biomass/coal gasification, combustion and synthetics due to their excellent performance along with high and stable conversion efficiency and feedstock flexibility. CFD (Computational Fluid Dynamics) can be used to reveal the details of hydrodynamic behavior and distribution of solid and gaseous species inside a fluidized bed which couldn’t be obtained from experimental measurement. A comprehensive CFD-CGM numerical model has been attempted to be used in simulation of biomass steam gasification in fluidized bed. The coarse grain method (CGM) numerical model was verified by comparing the hydrodynamic behavior and heat transfer predicted by CGM with the results by discrete element method (DEM) numerical model as well as experimental data in a lab-scale fluidized bed. CGM shows good performance and the computational time is greatly shorter than DEM numerical model. Then the CGM is used for gasification simulation. Effects of different operating temperature and Steam/Biomass ratio are investigated. The results show that higher temperature enhances the contents of CO and H2, higher S/B ratio improve the composition of H2 and CO2, but CO decreases. The concentration of different product gas species also shows a good agreement with experimental data. This indicates that the CFD-CGM can provide reliable and accurate predict results in fluidization behavior and also in gasification process. CGM could be a much useful method in large-scale fluidization reactor of gasification and combustion considering its short computational time.