| A 182mm diameter cylindrical spout-fluid bed with a draft tube and urea particles with a mean particle diameter of 2.2mm have been used to study hydrodynamics behavior of spout-fluid bed. According to change spouting gas velocity and fluidizing gas velocity, pressure drop and standard deviation of pressure fluctuation in the spout zone were measured and spout-fluid bed was divided into several different flow patterns. Then a new flow regime map could be gotten from the experiment. The effects of the diameter of spout nozzle, fluidizing gas velocity, the height of draft tube above distributor plate and bed height on minimum spouting velocity have been investigated. An experimental correlation was proposed for predicting minimum spouting velocity in spout-fluid bed with a draft tube. The effects of the diameter of spout nozzle, the height of draft tube above distributor plate, spouting gas velocity and fluidizing gas velocity on solids circulation have been investigated. The effects of spouting velocity, fluidizing velocity and height of draft tube above distributor plate on gas bypassing have been investigated. Based on the gas-solid movement theory and experimental results, a mathematical model was proposed to simulate solids circulation. It gave satisfactory agreement with those data measured in experiments.
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