错流微滤制备动态膜过程中细微颗粒沉积机理

Mechanism of micro-sized particle deposition in preparation of dynamic membrane with cross-flow microfiltration

以煤基炭膜为基膜,以ZrO2为涂膜颗粒,在实验研究的基础上对错流微滤过程中沉积颗粒进行受力分析,分别建立径向颗粒的可能沉积临界粒径模型、轴向上颗粒的可能移动临界粒径模型和圆周方向的颗粒可能滚动临界粒径模型。并以温度、错流速率、渗透通量为主要影响参数,分别对3种临界粒径模型进行模拟研究,探讨颗粒沉积机理。结果表明,压力增大(渗透通量提高)、温度降低以及错流速度降低,都可增大动态膜层厚度;由于净重力的影响,在水平膜管内圆周方向动态膜膜层厚度分布不均匀通过增加错流速率可明显减小此种差异;模拟结果与实验结果的一致性证实了所建模型的可靠性。

The critical particle size model was developed through analyzing the forces acting on a single particle with axial,radial and circumferential directions considered.The effects of feed temperature,cross-flow velocity and permeate flux on the critical particle size were investigated theoretically and experimentally,and the mechanism of particle deposition was discussed.Both simulation and measured results show that the membrane thickness becomes larger with the decrease of feed temperature and increase of trans-membrane pressure difference,and smaller with the increase of cross-flow velocity.Because of the net gravity,there exists a dynamic layer of non-uniform thickness along the circumference direction in the horizontal tube.This non-uniformity can be reduced evidently as the crossvelocity increases.The model calculation is in good agreement with the experimental results.