Hydrodynamic properties in an internally circulating fluidized bed (0.28 m I.D. × 2.6 m height) with a draft tube (0.1 m I.D. × 0.9 m height) have been determined. The effects of impact cap, particle size (86, 120, 170, 288 ㎛), inlet gas velocities to the draft tube (fluidized bed, up to 1.6 m/s) and to the annulus (moving bed, up to 0.125 m/s) on the bed voidage, solids circulation rate, elutriation and pressure drop across the orifices have been determined. The solids circulation rate has been measured by using two thermistor probes. Pressure drop across the orifices, the solids circulation rate and fluidized bed voidage increase with increasing gas velocity to the draft tube up to the ratio of gas velocity to the draft tube to terminal velocity $(U_d/U_t)$ of 1.8. Elutriation is greatly enhanced by increasing gas velocity to the draft tube. The solids circulation rate increases with increasing gas velocity to the annulus up to the minimum fluidization condition. Impact cap has a little effect on soilds circulation rate, bed voidage and pressure drop across the orifices below $U_d/U_t$ of 1.8. But elutriation decreases by 60 % with the impact cap. Solids circulation rate, pressure drop across the orifices and bed voidage decrease with increasing gas velocity to the draft tube above two times of terminal velocity $(2U_t)$.
The obtained pressure drop across the orifices in an internally circulating fluidized bed with a draft tube has been correlated as
▷수식 삽입◁(원문을 참조하세요)
($U_d/U_t ≤ 1.8$, with or without impact cap)
The obtained solids circulation rate has been correlated with the experimental variables as
▷수식 삽입◁(원문을 참조하세요)
($U_d/U_t ≤ 1.8$, with or without impact cap)
