Abstract:

The ceramic membrane process has been encountered with a problem of high energy consuming owing to that high crossflow velocities are necessary for the concentration polarization and membrane fouling control. On the other hand, the external loop airlift reactor is widely used in the field of chemical engineering. Thus, the application of air sparging in dextran ultrafiltration with ceramic membrane process is studied at different gas flow rates (Q_G). 87% increase in permeation flux was achieved while filtering 2 g·L^-1 dextran (2×10⁶) solution with the airlift crossflow operation of Q_G=400 L·h^-1. Hydrodynamics of the gas-liquid two-phase flow was characterized and the flux enhancement mechanism in the case of slug flow in tubular ceramic membrane was discussed.

Key words:

气升, 超滤, 陶瓷膜, 浓差极化, 葡聚糖

摘要：

为降低膜污染和浓差极化需维持较高膜面流速，能耗较高。将气升式外循环引入膜过程，可有效降低浓差极化和能耗。实验考察了曝气量对渗透通量的影响，当曝气量为400 L·h^-1时，与相同液速条件下单相流错流过滤相比较，膜通量提升87%；进一步增大曝气量，膜通量增加趋势变缓。对气升式膜过滤过程的水力学特性进行了研究，在弹状流条件下，气液两相流可有效提高膜面剪切力，增强膜面传质。在较低流速下，曝气可有效降低膜污染阻力，提高膜通量。结合气液两相流理论和膜过滤阻力模型，分析了弹状流提升膜通量的机理。

关键词:

气升, 超滤, 陶瓷膜, 浓差极化, 葡聚糖