Spouted Bed Gas-solid Two-phase Fluid Flow Numerical Simulation

Entered the 21st century, our nation's economy maintains an appropriate rapid growth to build a well-off society in an all-round way. So energy demand continues to rise, and the total emissions of SO₂ remains high. Powder-particle spouted bed developed by Japanese faculty is a new semidry flue gas desulfurization process. Besides much experimental work using optical probes, labeled ion, high-speed photography and other techniques to measure fluid flow inside spouted beds, numerical simulation has evolved into a useful tool to obtain detailed information about the fluid flow phenomena in spouted beds.The gas-solid flow behavior in spouted bed was simulated using the two-fluid model. The kinetic theory of granular flow was applied to describe the granular stress to close the governing equations. The interaction between gas and particle was described using the drag model, and the multiphase flow turbulence was simulated using k-εturbulent model. The solids volume fraction was high in the dense section of spouted bed, and the frictional stress between particles was considered. The pressure-velocity coupling was obtained by using the phase coupled SIMPLE algorithm.The results showed that the spouted bed typically displayed three distinct regions: spout, annulus, and fountain region. Before spouting came into being, there was slugging phenomena in the local of spouted bed. There was a neck near the jet. The calculated time average particle velocity and concentration profiles in spouted bed were in good agreement with the experimental results in the literature. The simulation values of minimum spouting velocity and fountain height were the same as the experimental values in the literature. By incorporating three drag models, including Gidaspow model,Syamlal & O'Brien model and Arastoopour model, into the two-fluid model, their influences on the simulation of fluid flow patterns in spouted bed were assessed. The simulation results by the three drag model showed that the Gidaspow model gave the best agreement with the experimental data. The frictional stress between particles had a significant effect on the flow of particles in the annulus. The coefficient of restitution had a great influence on the gas-solid flow behavior in spouted bed, and its value must be set based on reliable experimental data.