| As one of the important ways of dust purification,bag filter technology has been widely used.Glass fiber needle punched filter is favored by enterprises because of its excellent temperature resistance,good dimensional stability and low market price.However,the flue gas of different industrial sectors,such as coal-fired boiler and waste incineration,contains large amounts of corrosive gas with high temperature,which has seriously affected the performance and the life of filtration medium of bag filter.Therefore,it is of practical significance to study the high temperature resistance and corrosion resistance of the filter material.PTFE can be complementary with fiberglass filter material because of its good heat resistance and chemical resistance.Therefore,the PTFE material can be applied to the post-treatment of the filter material to improve the performance of glass fiber filter material.In this paper,the performance of untreated glass fiber filter,PTFE emulsion impregnated filter material and PTFE membrane filter material were tested.The effects of PTFE emulsion impregnation and PTFE microporous membrane coating on the performance of filter were analyzed;then,study was made on the optimum proportion of PTFE foaming coating agent and the optimum process parameters for the preparation of PTFE foam coating material by single factor experiment.Finally,PTFE foam coating filter was prepared,and the performance of the filter was tested.Compared with the untreated filter,the effects of PTFE foam coating on the performance of the filter were analyzed.The experimental results are as follows:(1)After the PTFE emulsion impregnation and PTFE microporous membrane coating treatment,the pore size distribution area is narrower,the average pore diameter is smaller,the air permeability is smaller,the filtration efficiency is higher;The PTFE membrane filter material has a high filtration efficiency of 93.08%,but the filtration resistance is significantly larger,and the filter quality factor is the smallest.It does not play a conspicuous role in enhancing the strength of the warp and weft of the filter media,but it has a significant effect on the wear resistance,heat resistance,acid resistance and oxidation resistance of the filter material.(2)When the concentration of the polytetrafluoroethylene(PTFE)emulsion is 20%,the concentration of the sodium dodecyl sulfate is 2%,the concentration of the hydroxyethyl cellulose is 1.5%,the concentration of the hydroxypropyl methyl cellulose is 0.5%,the concentration of the organsilicone-modified acrylates is 20%,the concentration of the waterborne epoxy baking resin is 5%,PTFE foaming agent has the high foaming speed,better foam stability,better film-forming ability and excellent oxidation resistance.When the curing temperature is 140℃ and the curing time is 300 s in the curing process,PTFE foam coating filter has smaller pore size and better air permeability.(3)The performance test results of the PTFE foam coated filter material: the surface of the filter material is “micro porous”;Compared with the untreated filter material,the pore size distribution is concentrated,the average pore size is smaller,and the air permeability is smaller;foam coated filter material has the advantage of higher filtering efficiency and lower filtering resistance.it has a significant effect on the wear resistance,heat resistance,acid resistance and oxidation resistance of the filter material.DSC test showed that the melting peak of the PTFE foam coating film was about 335 ℃,which improved the temperature range of the original glass fiber Needle Punched Filter Materials.In summary,the results of this paper may help to expand the market of the foam coated filter materials and achieve industrial production. |
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