不同操作压力下的气液过滤特性分析

根据ISO-12500标准建立了压缩空气滤芯性能检测系统，将操作压力由0.1 MPa升至0.7 MPa，分析了操作压力对亲油型和疏油型两种滤芯内的液体分布、滤材饱和度和过程压降的影响. 结果表明，操作压力对疏油型滤芯的过程压降、液体运移与饱和度有显著影响，操作压力每上升0.2 MPa，滤芯初始压降上升0.32 kPa，各操作压力下滤芯润湿压降(平衡压降与初始压降的差)为4.5~5.1 kPa，0.7 MPa时最后1层滤材饱和度比0.1 MPa时上升了71%，饱和度沿气体流动方向呈凹型分布，小面积润湿区域增多，稳态压降前出现短暂跃升阶段，可能加剧滤芯二次夹带，导致过滤器下游管道内液滴数增多，降低过滤器效率；操作压力对亲油型滤芯的初始压降影响显著，操作压力每上升0.2 MPa，初始压降上升0.39 kPa；操作压力对液体运移与饱和度影响较小，不同操作压力下各层滤材饱和度的分布规律相同，液体分布无明显差异.

Analysis of gas-liquid filtering characteristics under different working pressures

The oil droplet and powder in gas will caused serious damage to the equipment in the processes of dry gas seals, long-distance transmission of natural gas and large rotating machinery crankcase ventilation, the filter test under atmospheric pressure cannot accurately show the filter performance. According to the ISO-12500 standard, a performance testing system of compressed air filter was established, the experimental operating pressure can be adjusted from 0.1 MPa to 0.7 MPa. The effects of operating pressures on lipophilic and oleophobic filter’s liquid distribution, saturation and pressure drop were analyzed. The results showed that the pressure had a significant effect on the initial pressure drop, liquid migration and saturation of the oleophobic filter. When the operating pressure rose 0.2 MPa, the initial pressure drop of the filter rose by 0.32 kPa, the wetting pressure drop of the filter element (the difference between the equilibrium pressure drop and the initial pressure drop) fluctuated between 4.5 kPa and 5.1 kPa under each operating pressure. Compared with 0.1 MPa, the saturation of the last layer increased by 71% under 0.7 MPa. The number of small wetting area increased and there was a short jump stage before the pressure drop reached equilibrium under 0.7 MPa, this may aggravate the re-entrainment of the filter element, resulting in an increase in the number of droplets in the downstream pipe of the filter, reducing the efficiency of the filter. Influence of operating pressure on the initial pressure drop of lipophilic filter was remarkable, when the operating pressure rose 0.2 MPa, the initial pressure drop of the filter rose by 0.39 kPa. Operating pressure had little effect on fluid migration and saturation, each layer had the same filter saturation distribution, liquid distribution under different operating pressure.