LBM-DEM Mesoscale Simulation Of Two-Phase Flow In Dense Gas-Solid Fluidized Bed

Gas-solid fluidized bed(GSFB)is widely used in energy,chemical and other industrial processes because of its wide fuel sources,strong adaptability and controllable gas-solid flow.In dense gas-solid two-phase fluid system in fluidized bed,because the interaction between liquid phase and solid phase directly affects the mass,momentum and energy exchange,reaction rate and efficiency in the bed,it is of great significance to study the mechanism of gas-solid flow in fluidized bed for the design,manufacture and precise control of fluidized bed reactor.Based on the mathematical model of LBM-DEM coupling and considering the influence of solid motion on flow field,the gas phase is calculated by modified lattice Boltzmann method,the particle phase is treated by the soft sphere model o f discrete element method,and the fluid-solid coupling is modeled by Gidaspow drag force model.The dense gas-solid fluidization of single-hole and porous jets is deeply analyzed from the mesoscopic point of view.Flow mechanism in bed.The results show that fluidized area can be divided into the spouted area,nuclear area and dead area through the analysis of the instantaneous porosity;Particle's motion trajectory corresponds to collision force;The distribution of pseudo temperature and velocity shows the characteristics of "high in the middle,low in both ends";Potential energy and kinetic energy of particle fluctuate with the fluidized process,and potential energy is greater than kinetic energy.The variations of typical parameters of single jet and multiple jets systems are investigated under different jet velocities.The results show that spring eruption area enlarges with jet velocity of single jet system;However,when jet velocity of multiple jets system increases,bed expansion height improves 27.50%,the range of time averaged porosity enlarges and particles pseudo-temperature rises because the particles of central jet area get the high momentum.Also,there emerges the obvious jet combination in the spring eruption area of bed bottom.Jet combination height lowers 28.57%,potential energy of particles increases 66.07% and kinetic energy of particles decreases 48.48%.