(255b) Effect of Column Height and Diameter On Minimum Fluidization Velocity

Reducing the size of the fluidized bed is gaining interest because it requires small quantities of material, better gas distribution and good operability. Experiments show that minimum fluidization velocity of particles increases as the diameter of the column is reduced or if the height of the fixed bed is increased. These effects are related to the effect of the wall. A new semi-correlated model is proposed which incorporates Janssen's wall effect in Ergun's pressure drop equation to the calculation of the minimum fluidization velocity. The predictions of the model are compared to some existing correlations and experimental data.