Coupled Computational Fluid Dynamics and Discrete Element Method Study of the Solid Dispersion Behavior in an Internally Circulating Fluidized Bed

Abstract

The solid dispersion behavior in an internally circulating fluidized bed has been explored on the basis of the calculation results obtained with the computational fluid dynamics-discrete element method coupling approach. The general flow behaviors of gas and solid phases in the bed are presented, and the local dispersion behavior of solid phase is analyzed. Then, the global dispersion intensities in the two chambers of the bed are evaluated. Moreover, the influences of operating parameters and geometrical configuration on solid dispersion are discussed. The results show that the vigorously lateral dispersion of solid phase appears in the right region of the reaction chamber (RC), the region below the baffle, and the upper part of the heat exchanging chamber (HEC). However, the vertical one mainly locates in the RC. Larger global dispersion intensities of solid phase in both the lateral and vertical directions can be obtained in the RC as compared with those of HEC. In each chamber, the vertical dispersion intensity of solid phase is several times of the lateral one. Enlarging the superficial velocity of RC or HEC enhances the lateral and vertical solid dispersion behaviors. More complex response of the dispersion behavior can be obtained with baffle inclined. Increasing the gap height enhances the vertical solid dispersion in both chambers, while the lateral dispersion behavior is enhanced in the RC but suppressed in the HEC.