The Influence On Mechanism And Measurements Of Oleophobic Coalescence Filter Characteristics Element Under Different Gas Velocities

During the long-distance transportation of natural gas,a large number of droplet impurities carried by the gas will have a serious impact on the daily operation of downstream equipment.The coalescing filter element has excellent filtering effect for submicron small droplets,so it is widely used in the field of gas-liquid coalescence.At present,the research on gas velocity mainly focuses on the single constant gas velocity,but the flow is not constant in the actual working condition.Therefore,in order to explore the influence of the change of gas flow on the filtration characteristics of gas-liquid coalescence filter element,an experimental device for the filtration performance of gas-liquid coalescence filter element is established according to the relevant test standards in this paper.The influence of the change of gas velocity on the oil repellent coalescence filter element is studied,the material and structure of the coalescence filter element are optimized according to the experimental results.The research results show that both the constant increase and the continuous increase of the gas velocity have an impact on the filtration performance of the filter element.When the gas velocity increases constantly,the filtration efficiency of the filter element reaches the optimum when the gas velocity is 0.3 m/s,and there is basically no secondary entrainment.When the gas velocity increases continuously,the liquid holding capacity of the filter material on the inlet side of the filter element decreases,the number of liquid channels on the surface of the filter material increases,and the overall wetting area decreases,while the number of liquid channels on the outlet side increases with the increase of the area of the filter material.The overall wetting area decreases,while the area of filter material liquid channels and the number on the outlet side increases.Small liquid channels are connected to each other to form large liquid channels.As a result,the area of the clean filter material at the outlet side is reduced.The droplets are separated from the fiber and enter the downstream pipeline under the action of the air flow,resulting in secondary entrainment,and the filtration efficiency of the filter element is reduced.In order to improve the filtering performance of coalescence filter element,the filter element material is optimized.Three kinds of glass fibers with different accuracy levels and three kinds of liquid discharge layers of different materials are selected to make the filter element for experiment.According to the analysis of experimental results,when the gas velocity is 0.5 m/s,the medium precision filter material used in the experiment has the best filtering effect.Compared with the low precision filter material,there is basically no secondary entrainment at this time,and the filtration effect of 0.5μm droplets is better than that of high-precision filter materials.The use of new drainage layer materials can effectively reduce the phenomenon of secondary entrainment.It is found that changing the punching position of the inner framework,or installing a baffle inside the filter element to prevent the flow from directly impacting the bottom of the filter element can effectively improve the filtering performance of the filter element.In this experiment,when the punching height of the inner framework of the coalescing filter element is 2 cm from the bottom of the filter element,the secondary entrainment of the filter element can be effectively reduced.When the baffle height is15 cm,the downstream droplet count concentration is reduced by 97% compared with the structure without baffle.The research results aim to provide a new idea for optimizing the performance of the filter element and provide some guidance for the field application of gas-liquid coalescence filter element.