Numerical investigation of hydrodynamics in liquid-solid circulating fluidized beds under different operating conditions

A computational fluid dynamics (CFD) model was employed to investigate the hydrodynamics of the liquid–solid circulating fluidized bed (LSCFB). The numerical simulations of the flow in the LSCFB under different operating conditions, including different superficial liquid velocities, superficial solid velocities, particle densities and shapes, are carried out using the CFD model developed in the previous work. The numerical predictions show correct trends and good agreements with the experimental data. It is demonstrated that the radial non-uniformity and axial uniformity exist in the flow structures under different operating conditions. By increasing the superficial solid velocity, the average solids holdup and radial non-uniformity increase, while the opposite trends are observed by increasing the superficial liquid velocity. Besides, the solids holdup decreases with the decrease in the particle density. It is also observed that all the flow distributions in the radial and axial directions in LSCFBs are more uniform than those in GSCFBs.