液体粘度对气液固三相循环流化床颗粒循环速度和流型特征速度的影响

Effects of Liquid Viscosity on Particle Circulating Velocity and Flow Regime Characteristic Velocities in Gas-Liquid-Solid Three -Phase Circulating Fluidized Beds

实验的三相循环流化床以玻璃珠(dp=0.48mm,ρs=2460kg?m?3)和苯乙烯颗粒(dp=1.45mm,ρs=1264kg?m?3)为固相,空气为气相,水、0.05%、0.20%(mass)CMCS(羧甲基纤维素钠)水溶液为液相。实验研究了液体粘度、表观液体速度、表观气体速度、辅助液体速度及颗粒密度对颗粒循环速度的影响。随着液体粘度的增加,颗粒循环速度增加;随着表观液体速度和辅助液体速度增加,颗粒循环速度都增加;随着表观气体速度的增加,颗粒循环速度减小。低密度颗粒系统同高密度颗粒系统相比,低密度颗粒系统能提前从三相传统流型进入三相循环流型。实验还研究了液体粘度对低密度颗粒的起始液体速度和过渡液体速度的影响,为得到三相循环流化床的流型图提供了可靠的依据。

The effects of liquid viscosity, superficial liquid velocity, superficial gas velocity, secondary liquid velocity and particle density on the particle circulating velocity in a three phase circulating fluidized bed were studied. In the experiments, under a wide range of operation conditions, the glass beads （dp=0.48 mm, ps=2460 kg·m^-3） and styrene resin （dp=1.45 mm, ps=1264 kg·m^-3） were used respectively as solid phases, the water, 0.05%（mass） and 0.2%（mass） carboxymethyl cellulose sodium （CMCS） were used respectively as liquid phase and the air was used as gas phase. Experimental results show that the particle circulating velocities increase with increasing liquid velocity, superficial liquid velocity and secondary liquid velocity. However, the particle circulating velocities decrease with increasing superficial gas velocity. The three-phase circulating flow regime of particles with lower density can be carried out easier than the systems with particles of heavier density. Effects of the liquid viscosity on the onset liquid velocity （U1c） and liquid transition velocity （U1t） of the systems with low particle density were also studied. All these studies offer a reliable base for forming the flow regime map of the gas-liquid-solid three phase circulating fluidized bed operation.