Dynamic Microfiltration of Superfine Suspended Solids-Liquid Mixtures by Use of High-Speed Rotary Membrane Filter.

为了通过移动滤饼沉淀层来维持较高的滤液通量水平，对旋转动态过滤的运行方式进行了研究。高速旋转陶瓷过滤器的高效应用表明，几种浆料覆盖在高粘度的液-固体系中。1)采用孔径远小于悬浮固体颗粒大小的陶瓷膜，动态微滤遵循薄饼过滤原理。通过引入新定义的动态过滤系数，推导出了薄饼过滤过程的过滤速率方程。根据动态系数取决于作用于膜表面的剪应力和恒压过滤系数组成的控制变量，提出了旋转微滤的设计和评价依据。2)基于过滤速率方程，考察了错流过滤过程中滤液通量随时间的变化规律。过滤特性与许多操作变量有关，因为最终的稳定通量可以估计为膜剪切应力和恒压过滤系数的函数。3)在高粘度泥浆的错流过滤中，由于错流泥浆的流动性较低，有可能产生较高的剪切力，但在提高过滤速度方面存在一定的局限性。为了克服缩短过滤时间的困难，可以有效地利用浆液和膜之间的高速旋转产生的相对运动来实现粘性液-固体系的高通量过滤。

To maintain a high flux level of filtrate through moving the deposit layer of filter cake, the operational mode of rotational dynamic filtration was studied. The efficient applications of a high-speed rotating ceramic filter were shown using several kinds of slurries covering high viscous liquid-solids system.1) With a ceramic membrane of a much smaller pore size than the particle size of suspended solids, the dynamic microfiltration followed the principle of thin-cake filtration. A filtrate rate equation was derived for the thin-cake filtration process by introducing a dynamic filtration coefficient newly defined. On the basis of the fact that the dynamic coefficient depends on a controlling variable composed of the shear stress acting on membrane surface and the coefficient of constant pressure filtration, a basis for the design and evaluation of rotating microfiltration was proposed.2) Based on the filtration rate equation, the time dependence of filtrate flux was examined for crossflow filtration operation. The filtration characteristics were related to a number of operational variables, in view of the fact that the final steady flux can be estimated as a function of both the membrane shear stress and the constant pressure filtration coefficient. A reliable data analysis was proposed for evaluating the filtration performance.3) In the crossflow filtration of high viscous slurry, some limitations in increasing the filtration rate appeared though there being possibility of producing a high shear force due to the low fluidity of crossflowing slurry. For eliminating this difficulty of the reduction in filtration time, the relative motion between slurry and membrane, created by the high speed rotation of the latter, can be efficiently utilized to achieve a high flux filtration of viscous liquid-solids system.