Study On The Entraining Zone And Particle Flow Behavior Of Spout-fluid Bed With A Draft Tube

The flow characters of spout-fluid bed with a draft-tube, were studied in a Plexiglas column of 182mm i.d, using urea particles of 2.0mm i.d as bed material. Pressure drop in the entraining zone, particle velocity of radial and axial in the draft tube and the solids circulation were studied at different spouting gas velocities, fluidizing gas velocities and the diameter of spout nozzle. The result indicated that there was pressure difference between annular space and jetting zone. There was a velocity gradient in the radial direction of the draft-tube and it was impacted by diameter of spout nozzle and axial site of the draft-tube. The axial particle velocity and solids circulation varied with the variation of spouting gas velocity, fluidizing gas velocity and the diameter of spout nozzle. In the spout zone and annular space of the spout-fluid bed with a draft-tube, mass conservation equation and momentum conservation equation of gas and solid were established separately, and then mathematical model of the spout-fluid bed with a draft-tube was deduced. It gave satisfactory agreement with those data measured in experiments.