Theoretical and experimental study on hydrodynamic characteristics of fluidization in air–sand conical beds

Abstract

This work was aimed at modeling hydrodynamic characteristics of fluidization in conical beds using quartz sand as the inert bed material and air as the fluidizing agent. The minimum fluidization velocity, u mf , and the minimum velocity of full fluidization, u mff , were determined by Peng and Fan's models modified for conical fluidized bed. Meanwhile, the pressure drop across a bed, Δ p (including Δ p max and Δ p mff corresponding to u mf and u mff , respectively), was predicted by using modified Ergun's equations for variable superficial air velocity at an air distributor, u 0 . The predicted results were validated by experimental data for some operating conditions. Effects of the sand particle size, cone angle and static bed height on the fluidization pattern and hydrodynamic characteristics are discussed. With the proposed models, the Δ p – u 0 diagram were obtained with rather high accuracy for the conical air–sand beds of 30– 45 ∘ cone angles and 20–30 cm static bed heights, when using 300– 1180 μ m sand particles. For the predicted u mf and u mff , the relative computational errors were found to be within 20% for wide ranges of operating variables, whereas Δ p max and Δ p mff could be predicted with lower (10–15%) relative errors. With higher cone angles and/or bed heights, the computational accuracy was found to deteriorate.