Experimental and numerical investigation of solid behavior in a gas–solid turbulent fluidized bed

Abstract

The solid behavior in a turbulent fluidized bed was studied by combination of experimental measurements and computational fluid dynamics (CFD) simulations. Solid fractions were measured by optical fiber probe under three different superficial gas velocities and three different static bed heights at different axial levels. The experimental results showed that the lateral distribution of solid fraction is core-annulus and the operating conditions can influence the shape of the axial bed void profiles. In the CFD simulations, an Eulerian–Eulerian two-fluid model that incorporates the kinetic theory of granular flow was used to describe the gas–solid two-phase flow in a turbulent fluidized bed. A modified drag model was proposed using a scaling factor to reduce the universal drag laws, which accounts for the effect of particle clustering. The drag model can predict the coexisting regions, the bottom dense, bubbling region and the dilute, dispersed flow region observed in experiments. No significant difference was observed between results after application of laminar and turbulence model. The simulated axial bed void and radial solid fraction fit well with experimental data. The transient local solid fraction and the particle velocity were also investigated.