Study On The Numerical Simulation Of Membrane Filter Flow Field

Membrane fouling is the main problems existing in the filtration process. For constantspeed filtration process, the membrane fouling causes increase in filtration pressure. Thepaper mainly studys the constant speed filtration process, considering the influence ofpressure drop and filter cake layer formation on flux, temperature and filter structure.This paper establish three-dimensional physical model of PTFE membrane, using theporous medium model to study the pressure changes of the process of the PTFE treatment thedeionized and oily water. The results show that the filter pressure remains unchanged with theincrease of time for the pure filtration process, but the filter pressure is gradually increasingand the export oil content is gradually decreasing with the increase of time for the sewagefiltration process. The numerical results and experimental data of the literatrue is consistent,showing the porous medium model to simulate the membrane filtration process is correct andfeasible.The paper study the influence of the filter pressure on the structural parameters of inletstyle, filter arragement and the number of filter for multi-cartridge by using the numericalcaculation method. The results show that the filter pressure of the tangential inlet form is lessthan the filter pressure of the radial inlet form. The filter pressure is minimumal when thefilters are arranged evenly along the axis. For the same size filter, when the filter elementnumbers increase from two to three, the filter pressure is decreasing. However, when the filterelement numbers increase from five to six, the filter pressure is increasing. It shows that thefilter pressure difference along with the filter element number change is not liner changeregularity. The results can provide guidance for practical production to determine the structurearrangement and installation process.Based on the filter theoretical knowledge, the paper discusses the formation process ofcake layer during the filtration process. It simulate the cake layer formation process accordingto ergun formula and incremental analysis method, caculating sedimentary particles, theporosity of cake layer, the permeability of the cake layer, the specific resistance of the filtercake and the cake layer thickness change with the time during cake layer formation to analysisof the flux, temperature and membrane pore size on the influence law. The results show that the critical particles deposition on the surface of the membrane are gradually decreasing, thecake layer porosity is gradually decreasing, the permeability of the cake layer is graduallydecreasing, the specific resistance of the filter cake and the cake layer thickness is graduallyincreasing. Comprehensive considering, the biggest effect of flux is on the cake layerformation, however the smallest of temperature is on the cake layer formation.