旋转错流式膜分离设备膜过程的数学模型

Study on the Mathematical Model of the Rotating Cross Flow Membrane Separation Device

旋转式膜分离设备组因其结构简单,膜通量大,过滤速度快等特点而应用于国内外污水处理和水质净化等领域。但膜设备的工艺参数基本依靠经验和实验判断,缺少确切的数学模型分析。通过对膜片上过滤颗粒进行受力分析,并结合错流过滤受力特点,建立旋转过滤的数学模型。将旋转盘的旋转速度、盘间距、盘直径和颗粒直径等参数考虑在内,用滤饼层厚度反映膜污染程度,滤饼层厚度越小,说明水剪切力越大,膜通量衰减越少。通过分析稳定状态的滤饼层厚度,得到在盘径为0.25 m时最适宜的转盘角速度为略大于湍流速度3 rad/s;盘间距范围为5~15 mm。最后利用预处理过的生活污水进行实验对比,对比结果显示数学模型的符合度较好,曲线变化较一致。

With advantages of simple structure, high membrane flux and quick filtration, the rotating cross filtration group has been widely used in industrial water treatment, sewage treatment and water purification. However, the parameters of the membrane equipment always depend on experience and experiments, and lacking of accurate mathematical model analysis. In this article, with the method of analyzing the force state of the filter particles and builds the mathematical model of it. It is obvious that the disk rotation speed, disk space, disk radius and particles size determine the thickness of filter cake layer. And, using the cake thickness reflects the degree of membrane fouling, if the cake layer thickness is smaller it indicates that the hydraulic shearing force is larger, and less membrane flux attenuation. By analyzing the steady state filter cake thickness, the most suitable rotating speed velocity is slightly larger than the turbulent velocity, and the range of disk spacing is 5-15 mm in the case of the radius is 0.25 m. Compared with the experimental results, the figures show that the mathematical model is in good accordance with the experimental data, and the curves are consistent with the experimental results.