INTERNAL RECIRCULATION FLOW STRUCTURE IN VERTICAL UPFLOW GAS-SOLIDS SUSPENSIONS .1. A CORE-ANNULUS MODEL

A comprehensive, predictive two-region model has been developed to des cribe the core-annular internal recirculation flow structure in vertic al gas-solids upward flowing suspensions. This new model is more flexi ble by allowing axial variations of the core radius and the gas and pa rticle velocities in both the core and the annular regions. The validi ty of the model has been confirmed by good agreement between the predi cted values and the various experimental measurements reported in the literature, including the radius of core region, voidage in the core r egion, solids recirculation ratio and deposition coefficient.