旋流气升式环流反应器的气含率轴向分布

为强化环隙气升式环流反应器(AALR)的流动、混合与传质性能, 提出了旋流气升式环流反应器(HALR)。在8.8L的HALR中, 以空气-水和空气-水-K树脂为实验物系, 在表观气速为0.47～2.31cm/s的范围内, 研究了表观气速、导流筒底边与反应器底面的间隙(简称底部间隙)、上升区轴向高度及固体装载量等因素对气含率的影响规律, 并与 AALR 进行了对比。结果表明:对于空气-水组成的两相物系来说, 在表观气速较小时, 旋流片对上升气泡有聚并作用;在表观气速较大时, 旋流片对气泡主要起破碎作用;气含率随着轴向高度的增加而增加, 增加的幅度随表观气速的增加而增加。对于三相物系, 表观气速较大时, 气含率随着固体装载量的增大而增大, 比两相物系气含率高;表观气速较小时, 两相物系的气含率略高于三相物系的。根据实验结果, 提出并拟合出了上升区局部气含率与轴向高度的预测模型:ε_g=(3.00×10^-4h+0.0276)U_g^0.615, 模型的预测值与实验值吻合较好, 平均相对误差为12%。

Axial gas holdups of riser in Helical-flow Airlift Loop Reactors

A new type of helical-flow airlift loop reactor (HALR) has been developed to strengthen flow, mixing and mass transfer performance in the annulus airlift loop reactor (AALR).The local gas holdups in riser of the 8.8 liters HALR as superficial gas velocities, the bottom gap —— the distance between the lower end of the draft tube and the bottom of reactor, the height of the reactor, and solid loading were experimentally studied and were compared with the ones in AALR for the system of air - water and air - water -K resin, within the superficial gas velocity of 0.47—2.31cm/s. The results show that for air - water system, at the lower superficial gas velocities, swirling sheets made the rising bubbles coalescence ; at higher superficial gas velocities, the bubbles were mainly broken by the swirl sheets. Axial gas holdup was increased as the increasing of axial height, the increasing amounts of axial gas holdup increases with the increasing of superficial gas velocity. For the system of air - water -K resin, the gas holdup increases with the increasing of the amounts of solids loading in the higher gas velocity, when the superficial gas velocity is small, gas holdup for the system of air-water is slightly higher than the ones for the system of three-phase. The prediction model of the axial gas holdup in riser has been proposed based on the experimental results,, there is a good agreement between calculated and experimental data and the average relative error of 12%.