Canadian Journal of Chemical Engineering, Vol.78, No.1, 161-167, 2000
Pressure gradients, voidage and gas flow in the annulus of spouted beds
Parallel measurements of pressure gradients with a differential pressure probe and voidage profiles with a fibre optic system have been carried out to study gas flow distributions In the annulus of spouted beds, The observation of Grbavcic et al. (1976) that for a given fluid-solid combination and column geometry the annulus pressure gradient at any bed level is independent of bed depth was corroborated again. Calibration curves of pressure drops versus superficial gas velocities for beds of voidage higher than the lease-packed voidage were obtained by;applying the Ergun (1952) equation, mating it possible to estimate Superficial gas velocities in the annulus using the static pressure gradient method. The local superficial gas velocity in the annulus was found to be higher in a deep bed than in a shallow bed of the same material, contrary to the conclusion (Grbavcic et ai., 1976) that, for a given fluid-solid combination and column geometry, the annulus fluid velocity at any revel is independent of bed depth. Theoretical models and equations which do not account for the conical geometry near the bottom were found to underpredict superficial gas velocities in the annulus. Increasing the spouting gas flow wits found to increase the net gas flow through the annulus.