Influence of operating parameters and flow regime on solid dispersion behavior in a gas–solid spout-fluid bed

Abstract

The dispersion behavior of the solid phase in a three-dimensional spout-fluid bed was numerically investigated via the approach of coupled computational fluid dynamics and discrete element method (CFD–DEM), in which the fluid and solid phases were solved using the Eulerian and Lagrangian framework, respectively. Detailed trends of both the local and overall dispersion behaviors of the solid phase in the system were quantitatively studied, and the impact of various operating parameters (namely, spouting gas velocity (Usp), background velocity (Ubg), particle diameter (dp), the bed depth (L) and bed height) and flow regime on lateral and vertical solid dispersion was investigated. The results show that varying Usp, Ubg and dp affects the local solid dispersion in the spout and fountain regions more than the annulus. To enhance the overall solid dispersion, either Usp or Ubg or L can be increased, or dp and bed height can be decreased. Meanwhile, the total gas flow rate plays the dominated role for overall dispersion of solid phase. Finally, solid dispersion is the most effective in the Jet-in-fluidization regime, followed by the Spouting-with-aeration then the Intermediate/spout-fluidization regimes.