| At present, the fog and haze weather appear frequently, it has seriously affected People’s Daily life and health. Industrial dust emissions is one of the main sources of PM2.5, accounted for30%～60%of the total PM2.5. In industrial furnaces, how to control emissions of fine particulate matter more effectively has become a research hotspot in the field of environmental protection. Baghouse is one of the main techniques to control the industrial flue gas, has been widely used in the field of dust removal. Currently for how to control PM2.5, how to improve the technology of baghouse, how to realize high filtration efficiency and low flow resistance especially from the filter material point of view, it’s the problem urgently to be solved in the current technology of bag-type dust collector.Based on the analysis of the existing filtration theory, the technology of filter bag can be divided into two aspects were studied in this paper. First, research of the filter material, in order to improve the filtering efficiency for PM2.5, experimental study on fabric structure from fiber, fabric, filter.secondly, optimization analysis the filter bag sewing technology.This thesis focuses on the following elements:(1) From the perspective of the fiber, fiber strength and specific surface area of fine fiber, trefoil fiber and conventional cylindrical fiber were studied. The results show that the linear density of the fibers increases, the strength increases, but the intensity value (the value of the unit fineness strength) instead gradually decline, and increases the strength unit fineness of fine fibers. Trefoil fiber strength slightly smaller than its line close to the density of cylindrical fiber, associated with its cross-sectional, the middle part of the increased strength effect compared with the cylindrical fiber is smaller. Test results obtained from the specific surface area:When fiber fineness decreases1.1dtex, the specific surface area doubling. The specific surface area of trefoil fiber is112%larger than the cylindrical fiber.(2) From the view of the strength of base fabric analysis, three different base cloth was selected to test. The results showed that:Pure PTFE fabric has maximum strength. Pure PPS take second place. PPS and PTFE blend fabric’s strength is minimum. Analysis its reason, shrinkage rate of PPS and PTFE is different, PPS yarn and PTFE yarn discontinuity in the process of drawing, resulting that PPS and PTFE mixed base fabric’s strength is less than the pure fabric.(3) Filtration efficiency experimental study was carried on seven different fabric structure forms (different ratio of fiber proportion and filter layer form) of the filter material of bag-type dust collector. Test in the fabric structure were analyzed by fiber fineness, specific surface area, fabric post-processing technology on PM2.5particles filtration efficiency and the influence of resistance. The results show that post processing impregnated PTFE emulsion has a significant effect on the filtration properties of the filter material. Compared with the conventional filter material, the surface of the filter material fiber thinning and heteromorphosis can increase the filtering efficiency of PM2.5effectively, and resistance is smaller. Static filtering under laboratory conditions, using filter quality factor Q to comprehensive evaluate the filtration efficiency and resistance of filter material. The Q value is the largest that mixed with100%of superfine fiber filter material in the surface.Mixed with50%of the fine fiber media and50%trefoil fiber filter is the second. Effect of filter material is minimal. The material made of fine fibers and trilobal fibers not only improves the filtration efficiency of the filter, and the resistance increased slowly, realize the high efficiency low resistance of the filter material.(4) Using VDI (filter material simulation tester) to simulate the filtration efficiency and resistance of filter in operating process. The experiments include three stages, the clean filter (0to30cycles), aging injection (5000times), a stable operating condition (6h). The results show that the efficiency of the membrane filter material filtering the PM2.5is highest and the resistance is least. Due to the microcellular structure of the membrane surface, the membrane filter soot cleaning thoroughly. The filter material with trefoil fiber is increased contact with the dust filter area. its filtration efficiency is after coated filter material. Filter efficiency of superfine fiber material is inferior to trefoil fiber filter material, higher than that of ordinary conventional fiber filter material. Filtration efficiency is directly proportional to the size of the specific surface area. Using filtering quality factor Q to comprehensive judge the efficiency and resistance of filter material, QM>QT>QF>QN.(5) For the phenomenon that the emission of PM2.5increase instant after the soot cleaning, considering the agglutination of technology to improve pinhole problem. The experiment was did to contrast filtration efficiency before and after the agglutination. Experiments in high temperature have been done also. The results show that filtration efficiency becomes lower when the number of sewing thread becomes more. Filtering efficiency is reduced by1%-5%when increase a sewing thread. Per unit length of sewing thread affect the filtration efficiency is12%-25%for particles (dp=1μm). The influence of filtration efficiency of each pinhole for PM2.5is0.045%to0.227%. Efficiency for particles (dp=1μm) was improved significantly by optimizing the sewing interface. About the influence factors in the experiment, the speed of airflow is greater than temperature.(6) For safety aspects of filter material,8kinds of common filter material’s limit oxygen index and anti-static level was compared. Combustion test results that Polyester belongs to flammable material, is not fit to use in high temperature. Flame retardant properties of polysulfonamide, PTFE, PPS, Basalt, and PI are all in the B2(flame retardant) even B3(non-combustible). By comparing the PPS1and PPS2, it was found that material by PTFE impregnated or PTFE coated method to increase the oxygen index value, improve the flame retardant performance of filter material. Static electricity test results that Dacron, fang polysulfonamide and PI are antistatic materials. The antistatic performance of PPS, PTFE and basalt are grade A. The result that adopting fiber mixed preparation technology can change the filter material’s antistatic property from the contrast experiment of static electricity that basalt woven microplush, fang polysulfonamide felt and double blanket felt of basalt+PSA. Antistatic grade of good material and poor material mix knitted, the antistatic performance of filter material was improved.Improve the cleaning effect of PM2.5involves a host of other devices and operational management. The result of this research is obtained under laboratory conditions to provid a reference to the baghouse engineering applications. |
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