(380ar) Gas-Solid Hydrodynamics and Hysteresis in a Rectangular Spouted Bed

A spouted bed is a special case of the fluidized bed in which the gas is injected into the granular bed through a single centered orifice. It is used as a gas-solid contactor in various industrial applications (such as combustion, drying, chemical vapor deposition) due to better heat and mass transfer. In the present work, particle dynamics in a pseudo-2-D rectangular tapered spouted bed has been studied numerically by coupling computational fluid dynamics (CFD) for fluid phase and discrete element method (DEM) for particle phase. In the gas phase momentum equation, k-ε two-equation turbulence model has been used to capture the effect of turbulence. Fluid-particle interaction force has been incorporated using Gidaspow drag model. The minimum spouting velocity is obtained numerically for a fixed bed height. Experimental measurements are also carried out in a similar spouted bed for different particle size and static bed height. The simulated pressure drop has been compared with the experimental results. Hysteresis in the pressure drop in numerical simulations has been compared with experimental findings when the superficial gas velocity is cycled up and down successively. We have also investigated numerically the effect of superficial gas velocity on bed expansion, the longitudinal profile of particle maximum axial velocity, and voidage profile. The maximum solid velocity and its fluctuation are observed to occur in spout zone. The effect of fluctuating particle-particle contact force is found to be significant in the dilute spout regime.