Numerical Simulation of Biomass Gasification Considering Anisotropic Fluctuation of Multiphase Particles in Bubbling Fluidized Beds

Second-order moment (SOM) model considering anisotropic movements of multiphase particles was presented. Biomass gasification processes in bubbling fluidized beds were described combining with a chemical reaction kinetic method. The simulated gas molar fractions were compared with kinetic theory of granular flow (KTGF) model and SOM model. The instantaneous distribution of concentration and temperature of two char particles was given with their velocities analyzed. The results show that the velocity distribution was similar between these two particles, which indicate that the two char particles were well mixed. The second-order moment of the two char particles were analyzed, which is larger for the particle with diameter of 2.0 mm in axial and radial directions. Velocity fluctuation is enhanced with the increase of particle size. The anisotropy of velocity fluctuation for the two char particles was simulated as a function of char particle concentration, which is weakened with particle concentration increase. Moreover, the anisotropy of the char particle with smaller diameter is more obvious in the computational domain.