Laboratory Experimental Study On Filtration Performance Of Oil Mist Filter

In industrial processes such as natural gas transportation,metal cutting,compressed gas and crankcase ventilation,gas usually contains a lot of droplets,which can not only corrode mechanical equipment,but also increase operating costs and cause harm to the environment and the human body.The coalescing filter can effectively remove the droplets in the gas,which is the most common method for gas-liquid separation.Therefore,it is important to experimentally research the gas-liquid filtration performance of coalescing filter.The filter layers of the coalescing filter element usually consist of folded filter layers and a winding filter layers.However,in practical applications,the folded filter layers of homemade filter elements are seriously entrained.After a long time operation,the liquid hold up of the winding filter layers grows steadily,resulting in the increase of pressure drop and the decrease of efficiency.In order to research the filtration performance of the folded structure and the winding structure of high-precision coalescing filter,a gas-liquid filtration performance experimental device for coalescing filter was built according to the ISO-8573-2 standard,and the folded filters and the winding filters were tested.The effect of coating binder on the face of folded filter,oil mist concentration and filter face velocity on the filtration performance of the folded filter element was analyzed,and the effect of oil mist concentration and the pore size of filter material on the filtration performance of the wound filters was tested.According to the result:(1)Coating adhesive reduces the median pore diameter of the folded filter material by about 50% and increase the anti-tensile strength of the folded filter material by 260% to 270%.(2)Because the binder is mainly concentrated in the area where the permeability of the filter material is low,coating binder has little effect on the pressure drop of the folded filter elements;the binder can inhibit the occurrence of entrainment,however,when the binder is peeled off,the efficiency of the folded filter coated with the binder will decrease.(3)When the oil mist concentration increases,because the liquid drainage capacity of the filter element with smaller pore size is lower than that of the filter element with lager pore size,the saturation and channel pressure drop of the filter element with smaller pore size increases faster than that of the filter element with lager pore size;when the oil mist loading rate exceeds the liquid drainage capacity of the winding filter element,the pressure drop and saturation of the winding filter element continue to increase slowly with time during the steady state stage,and the pressure drop growth rate of the winding filter element with smaller pore size is larger.(4)The increase of oil mist concentration will increase filter saturation,which leads to the growth of the entrainment rate of submicron droplets;and the bubbles generation rate on the rear face of the winding filter element also increases,resulting in the increase of the re-entrainment rate,which leads to the filtration efficiency of the winding filter element decreases.The research results provide reference for the optimization of gas-liquid filtration performance of coalescing filters and design of gas-liquid filtration project.