Research On Dynamic Characteristics And Backwashing Mechanism Of High Water-based Liquid Return Filter

The high water-based liquid return filter is mainly applied to the liquid return pipe of the hydraulic support to provide a clean emulsion for the hydraulic support actuator during operation.At present,with the continuous improvement of the mining demand and the fully mechanized mining technology,the liquid return filter filtration efficiency and accuracy are becoming more and more demanding.The structure of the liquid return filter,the backwashing system and the backwashing principle will directly affect the filtration efficiency and service life of the filter.In addition,the working environment in the underground is bad,and the solid particles such as rock and pulverized coal in the emulsion will cause erosion and wear on the filter,which damages the parts of the filter that have sealing requirements and affects the reliability of the liquid return filter.Therefore,this paper takes the hydraulic support liquid return filter as the research object,from the structural design of the liquid return filter,the hydraulic system pressure loss calculation and simulation,the liquid-solid two-phase flow to the filter erosion and pressure drop simulation,affecting the liquid return filter backwashing factors and backwashing dynamic mesh simulation,etc.Research on the dynamic characteristics of the liquid return filter and the backwashing mechanism,effectively improve the filtration efficiency and backwashing effect of the liquid return filter,ensuring the filter's performance and safety and reliability.Firstly,the structure and filtration system of the high water-based liquid return filter were studied.A filter consisting of upper and lower cylinder assemblies was proposed.The upper and lower cylinders were connected together by a clamp assembly.The liquid return filter has two working states:filtering state,backwashing state,in order to improve the automation degree of the liquid return filter in the downhole,a backwashing filtration system using the pressure difference control or timing control of the inlet and outlet of the filter is proposed,and the pressure loss of each component in the filter during the filtering state is analyzed and calculated.The pressure-flow characteristic curve of the liquid return filter was obtained by establishing a liquid return filter component model and a filter system model by AMEsim and performing simulation analysis.Secondly,the two-dimensional model of the liquid return filter in the filtering state is established by using ICEM CFD,and the structure mesh is divided.Simulation analysis of wall erosion wear and filter pressure drop of filter using discrete phase model and porous media model in Fluent.The simulation analysis shows that the flow rate of the emulsion at the inlet and outlet of the filter is about 22m/s;when the permeability of the filter is3.306?10^-13m²,the pressure loss of the emulsion after passing through the filter is about 0.018MPa.The erosion wear of the liquid on the filter is mainly concentrated on the control check valve and the liquid return outlet seal ring,and the maximum erosion wear rate appears at the liquid return outlet seal ring,and its value is 1.13×10^-6kg/?m²?s?.Finally,the backwashing mechanism of the filter and the peeling mechanism of the filter cake were studied.The impact force and the filter core speed were used to characterize the cleaning effect of the filter element.The jet aperture,the hole distance and the jet angle were studied respectively.The effect is obtained by Fluent 6DOF dynamic mesh simulation:when the jet pressure is20MPa,the jet diameter is 1.5mm,the hole pitch is 19.6mm,and the jet angle is24°,the filter cleaning effect is the best.