Investigation and modeling of cocurrent downflow circulating fluidized bed (downer)

To simulate the gas and solids flow structure in downflow circulating fluidized beds or downer reactors, a two-dimensional two-phase turbulence hydrodynamic model (κ - ε turbulence model) was developed. The influence of solid particles on the turbulence structure of the gas phase has been considered in deriving the hydrodynamic model. An improved numerical method (based on the SIMPLE method) is used for the flow model calculation. The predicted radial distributions of axial gas and particle velocities are in good agreement with the experimental data determined by LDV measurement. This turbulence hydrodynamic model provides a good description of the gas and solids flow structure in the downer.