Experimental Research On The Performance Of PTFE Compound Filtration Medium Of Bag Filter

The flue gas of different industrial sector, 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. The research on the application of PTFE needle felt and PTFE compound filtration medium made of domestic PTFE fiber is worthy of being studied as PTFE fiber has the properties of corrosion resistance and thermal resistance, thus will definitely promote the development and application of bag filter technology and bring significant economic & social benefits and help to optimize the project.In order to evaluate the thermal resistance and corrosion resistance of different filtration medium with different fiber and after treatments, the tensile strength and tensile elongation of five filtration medium: coated 100% PTFE needle felt, uncoated 100% PTFE needle felt, composite gradient filter medium of PTFE fiber+fiberglass felt with PTFE membrane and chemical treatment and PPS needle felt were tested, which immersed in H₂SO₄ or NaOH with different concentration in the lab to simulate the application environment. The tests showed that filtration medium with different fibers and after treatment obviously could enhance the strength of filter media. Meanwhile, some suggestions were given for optimizing the the testing technology of filtration medium.To control the discharge of major pollutants, especially of the fine particulate matter, a testing device for grade efficiceny of filtration medium was designed. Filtration medium with different type (HST gradient filter, conventional needle felt, FMS needle felt and P/G membrane filtration medium) in cleaning and dust collection were tested. The results showed that grade efficiency was diverse with particle size, and the efficiency in dust collection was significantly higher than that in cleaning state. Overall, grade efficiency of different filtration medium from high to low was: membrane media, compound gradient filter, compound needle felt and conventional needle felt. Optimized testing device was also given to test the efficiency of fitration medium in fatigue state and its dynamic performance.Based on the testing and research on different filtration medium with dust collection which using medical dust as the testing dust, a mathematical method was used to visualize the changes of pressure drop, which showed that pressure drop was linearly proportional to filtering velocity in cleaning state and turned to be quadratic correlation with dust cake. Thus the cleaning cycle time of different filtration mediun in flat state was calculated which could help ensure the dust cleaning interval under an actual case.Combined the experimental research with an actual case, new type filtration medium was developed and its cleaning cycle was calculated. Meanwhile, the correction coefficient K would still need be further studied to modify cycle time concerning the the changeable dust concentration, which emphasizesed the design of bag filter should be pay great attention as inlet airflow and cleaning mode had great importance on the performance of equipment.