Hydrodynamic characteristics of spout-fluid bed: Pressure drop and minimum spouting/spout-fluidizing velocity

摘要

Experimental investigations on the hydrodynamic characteristics were carried out in a two-dimensional spout-fluid bed with cross section of 300 mm x 30 mm and height of 2000 mm.Six kinds of Geldart group D particles were used as bed materials.The effects of static bed height,particle property,spout nozzle width and fluidizing gas velocity on the pressure drop,maximum spouting pressure drop,minimum spouting velocity and minimum spout-fluidizing velocity were systematically studied.The results show that the total bed pressure drop appears a spouted bed characteristic when increasing the spouting gas velocity and keeping the fluidizing gas velocity constant,while it appears a fluidized bed characteristic when increasing the fluidizing gas velocity and keeping the spouting gas velocity constant.The maximum spouting pressure drop required to initiate spouting increases with static bed height and particle density,but decreases with particle diameter,spout nozzle width and fluidizing gas velocity.The minimum spouting and spout-fluidizing velocities both increase with static bed height,particle diameter,spout nozzle width.The minimum spout-fluidizing velocity increases while the minimum spouting velocity decreases with fluidizing gas velocity.Additional,correlations considered all of the above effects were developed to predict the minimum spout-fluidizing and spouting velocities of the spout-fluid bed,which were in satisfied agreement with the present experiments and some published experimental results.