Hydrodynamic Performance of a Spout-Fluid Bed with Draft Tube at Different Temperatures

Temperature is one of the key factors exerting a strong effect on the hydrodynamic performance of spout-fluid beds. In this study, experiments were conducted in a 160-mm-diameter spout-fluid bed with a nonporous draft tube at four temperatures: 293, 373, 440, and 500 K. The effect of temperature on the hydrodynamic performance indexes of pressure drop, gas bypassing, minimum spouting velocity, and flow pattern was investigated. The pressure drop in the annular region was higher at 500 K than at 293 K. The minimum spouting velocity (U-ms) increased with temperature at a low superficial fluidizing gas velocity (U-ms < 0.010 m/s). However, U-ms decreased with temperature at a high superficial fluidizing gas velocity (U-ms > 0.020 m/s) because the amount of gas flow rate transferred from the fluidizing gas into the draft tube increases with temperature. Six flow patterns identified by pressure drop fluctuations and digital images show that the gas velocity ranges in the two flow regimes of spouting with aeration and spout-fluidization are narrow or limited at 500 K compared with those at 293 K. The effect of temperature on these hydrodynamic performance indexes should be considered in the use and design of spout-fluid beds.