Analysis Of Gas-Liquid Filtering Characteristics Under Different Operating Pressure

Natural gas impurities are inevitably mixed in the process of natural gas extraction and transportation.These impurities will threaten The safe operation of long distance pipeline system will be threaten by these impurities.At present,the research on coalescence filtration is mainly carried out under normal pressure,but in industrial practice,the filter is mostly applied to the operating pressure higher than the normal pressure.The increase of operating pressure will lead to the obvious change of the properties of gas and the structure of the filter,and then affect the filtration process of the hydrophobic filter.The research of filter under air pressure can not accurately represent the characteristics of filter element.According to the standard ISO12500 of compressed air filter,the experimental equipment of gas-liquid filtration under different operating pressure is set up.The operation pressure regulating range of the experimental equipment is 0.1MPa~0.7MPa.In this experiment,5 kinds of filter material common in industrial application was tested under different operating pressure,and explore the filtration characteristic of the filter.The pressure drop of the filter during the experiment is recorded.The saturation is calculated and the liquid distribution on the surface of the filter is observed when the filter is disassembled after the experiment.The main results are as follows:(1)The density of the gas in the pipe will increase when the operation pressure rises,which causes the increase of the initial pressure drop of the filter,At the same time the increase of the operating pressure causes the filter media to be compressed,the average pore diameter decreases.As a result,the performance of the filter element measured in the laboratory does not accurately reflect the true performance of the filter element in the high pressure field;(2)The wetting pressure drop of the filter under the different operating pressure is basically the same,but the increasing of the operating pressure results in the final layer of filter material producing liquid film,the larger the average pore size of the filter material,the worse the oleophobic capacity,the more obvious the effect of the operation pressure increase,increase the liquid holding capacity of the entire filter,the droplets produced by the rupture of the liquid film are again entrained downstream by the air stream,which will result in a decrease in the efficiency of the filter element;(3)The increasing of the operating pressure will compress the filter layer and lead to aggravate the infiltration of liquid in the glass fiber felt to the near filter material for the oil filter which sets the glass fiber felt protection layer on the inner and outer sides of the filter layer;(4)The increasing of the operating pressure has no significant influence on the lipophilic filter,the increase in operating pressure has no significant effect on the outer liquid membrane of the lipophilic filter cartridge.,and the wetting pressure drop of the lipophilic filter under different operating pressure is almost unchanged.The research results provide reference for design,performance prediction and analysis of gas-liquid separation filter under high pressure.