Numerical Simulation of the Gas-Solid Flow in a Square Circulating Fluidized Bed with Secondary Air Injection

The dynamic behavior of gas-solid flow in an experimental square circulating fluidized bed setup (0.25 m × 0.25 m × 6.07 m) is predicted with numerical simulation based on the theory of Euler-Euler gas-solid two-phase flow and the kinetic theory of granular flows. The simulation includes the operation cases with secondary injection and without air-staging. The pressure drop profile, local solids concentration and particle velocity was compared with experimental results. Both simulation and experimental results show that solids concentration increases significantly below the secondary air injection ports when air-staging is adopted. Furthermore, the flow asymmetry in the solid entrance region of the bed was investigated based on the particle concentration/velocity profile. The simulation results are in agreement with the experimental results qualitatively.