基于固体颗粒尺寸分布的微孔滤膜堵塞机理分析

Fouling Mechanism Analysis on Micro-pore Filter Membrane based on the Solid Particle Size Distribution

滤膜堵塞法是一种半定量的油液污染度检测方法,研究固体颗粒尺寸分布与滤膜堵塞机理的关系有助于该检测方法的定量化。利用AC细粉尘及煤粉配制了8种不同尺寸分布的悬浮溶液,选择了10μm、15μm两种不同尺寸的微孔滤膜,对其堵塞机理与溶液中固体颗粒尺寸分布的关系进行试验研究。基于膜孔尺寸将颗粒划分为可通过颗粒、敏感颗粒、架桥颗粒及易挡孔颗粒,将溶液恒压下通过微孔滤膜的流量衰减曲线与经典堵塞模型的堵塞指数相结合,分析不同类型颗粒在膜孔堵塞中的作用以及不同颗粒尺寸分布对应的滤膜堵塞机理。分析结果表明,微孔滤膜堵塞机理与溶液尺寸分布规律相对应,与膜孔尺寸的选择无关;溶液中的敏感颗粒越多,对滤膜的初始堵塞会越严重,越易形成滤饼;对于可通过小颗粒较多、敏感颗粒和架桥颗粒适量、易挡孔颗粒较少这种液压系统中常见的颗粒尺寸分布规律,微孔滤膜的堵塞以标准堵塞—滤饼过滤为主要机理。首次从颗粒尺寸分布的角度分析微米级滤膜堵塞机理,分析结果有助于建立滤膜通量与固体污染颗粒尺寸分布之间的关系,从而提高滤膜堵塞法的油液污染度检测精度。

The filter membrane blockage method can semi-quantitatively determine the particulate contamination level in the oil medium of a hydraulic system, and the study on the relationship between the solid particle size distribution and the fouling mechanism of the filter membrane is helpful to establish the quantitative detection method. Eight kinds of suspensions in different particle size distributions are prepared with AC fine test dust and coal dust. Two different sizes of micro-pore filter membranes with pore size of 10 ?m and 15 ?m are chosen. The experimental studies on the relationship between the filter blocking mechanism and the solid particle size distribution are carried out. Based on the membrane pore size, the solid particles in the suspension are divided into four kinds of particles, which are easy-to-pass particles, the sensitive particles, the bridging particles and the easy-to-block particles. Joining the flow attenuation curves caused by the tested suspensions flow through the gradually blocked filter membrane and the blocking index got by fitting the classical fouling model, the role of each kind particle taken in the membrane pore fouling and the possible membrane fouling mechanisms for suspensions in different particle size distribution are analyzed. Analysis results show that the filter blocking mechanism is corresponding to the rule of the size distribution and has nothing to do with the membrane pore size. The more quantities of the sensitive particles the suspension has, the more serious the initial blockage will be, and the easier for the membrane to form a cake. For the particle distribution rule which the hydraulic system always has like that the easy-to-block particles are in large quantity, the sensitive particles and the bridging particles are in a little amount and the easy-to-block particles are in less, the main fouling mechanism for the membrane is standard blocking-cake filtration. For the first time the blocking mechanisms of the micron filter membrane are analyzed from the view of the particle size distribution. The analysis results are helpful for establishing the relationship of the filter membrane flowrate and the solid particle size distribution and thereby improving the accuracy of oil contamination level detection. *