Through the analysis of the dust removal mode of bag filter and the comparison between deep filtration and surface filtration, the application advantages of membrane-covered filter media are summarized. In particular, the advantages of the membrane filter media are more prominent because of the difficulty of cleaning the long bag. Finally, a quantitative comparison is made for the cleaning performance of filter media.
Membrane-covered filter media, ash removal performance, ash removal method, ash removal effect, deep filtration, surface filtration, environmental technology certification, ETV, ash removal times, pressure difference, energy consumption.
Bag type dust removal technology has made rapid progress in industrial applications in recent years, especially in cement production. The early bag filter technology mainly used ordinary needle felt filter material. However, the surface of the filter material is not very smooth, the filter layer is very large and uneven, thus forming a deep filter, which has a substantial effect on its filtration performance and service life. For dust collection with large particle size (>5um), ordinary filter media are usually recognized. However, it is not applicable to sub micron particles with smaller particle size. The main shortcomings of the ordinary filter material are: because the fine dust is very easy to penetrate and lead to high emission; because the filter material is easily blocked by the dust, the pressure difference is high; the cleaning period is short and the service life is short; the emission fluctuation is great before and after the ash cleaning. Discharge fluctuation is mainly due to the dust inside the filter media was removed after a short period of time, the filter material pore is larger, resulting in dust penetration caused.
ln order to eliminate the above shortcomings, it is an ideal solution to add dense filter layer on the surface of ordinary filter media. This theory was put forward. As early as 1973, Gore company in the United States first introduced the filter material covering the expanded polytetrafluoroethylene (ePTFE) film in the world, and put forward the concept of surface filtration. This compact filter is a layer of continuous homogeneous multi microporous optical slide film coated on the surface of ordinary filter material, which has the advantages of the following aspects:
1. improve filtration efficiency, especially for sub micron particles with smaller particle size.
2. because of its lower and more stable pressure difference, product quality and system reliability can be improved.
3. the pressure difference of filter bag is low, which has good dust peeling property and good dust removal performance.
4. low cleaning frequency can greatly prolong the life of filter bags.
5. film filter material instead of ordinary filter material and the optimization of surface filtration can greatly improve the filtering performance. The life of the filter material is longer, the filtration efficiency is higher, the dust emission is low, and the EU Emission standard can be satisfied and the system shutdown time is reduced. It has been proved by practice that the frequency of dust cleaning can be reduced to 50 cycles per day from 360 cycles per day of ordinary filter material by using the coated filter material of Gore company. Under the same conditions, the filter material of the dust collector system can be more than 600Pa above the ordinary filter material.