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保持较高的滤液通量，研究了旋转动态过滤的运行模式。介绍了高速旋转陶瓷过滤器在覆盖高黏度液固体系的几种浆料中的高效应用。1)动态微滤采用比悬浮物粒径小得多的陶瓷膜，采用薄饼过滤原理。通过引入新定义的动态过滤系数，导出了薄饼过滤过程的过滤速率方程。基于膜表面剪切应力和恒压过滤系数共同构成的控制变量决定了膜的动态系数，为旋转微滤的设计和评价提供了依据。2)根据过滤速率方程，考察了横流过滤过程中滤液通量的时间依赖性。考虑到最终的稳定通量可以作为膜剪切应力和恒压过滤系数的函数来估计，因此过滤特性与许多操作变量有关。提出了一种评价过滤性能的可靠数据分析方法。3)在高黏度浆体的横流过滤中，虽然由于横流浆体流动性低，有可能产生较大的剪切力，但在提高过滤速率方面存在一定的局限性。为了消除这种减少过滤时间的困难，可以有效地利用浆液和膜之间的相对运动，由后者的高速旋转产生，以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.