Chiang Mai Journal of Science

The hydrodynamic behavior of a gas-solid flow in a 14-m high riser with a 45^o inclined standpipe using a venturi pipe inlet was predicted using a transient three-dimensional hydrodynamic model. The model based on the kinetic theory of a granular flow was constructed using commercial computational fluid dynamics (CFD) software. The hydrodynamic behaviors of the gas-solid flow in the risers with a conventional straight pipe inlet and with a venturi pipe inlet were compared. In addition, the effect of throat diameter of the venturi pipe was studied. The solid concentration over the cross-sectional area of the riser is asymmetric because of the asymmetry of the particle inlet. The simulation results showed that a riser with a venturi pipe inlet can improve the solid flow behavior in the region near the riser entering region. In the riser with a venturi inlet, the solid particles flow in the standpipe with less gas blocking and higher velocity than those in a riser with a conventional inlet. The throat diameter has significant effects on the flow pattern in the riser. The solid velocity increases as the throat diameter decreases. Therefore, a venturi pipe inlet with proper design can decrease the backward gas flow into the standpipe.