Difference of dust removal mechanism of different filter materials in bag filter

1. Differences in dust removal mechanism of different filter materials

1) the pores of filter material exist between warp and weft yarn (generally, the wire diameter is 300~700 μm, and the gap is 100~200 μm), and between fibers, while the latter accounts for 30% ~ 50% of all pores. At the beginning of dust filtering, most of the airflow passes through the small hole between the warp and weft yarn, only a small part of dust passes through the fiber gap, coarse particle dust is embedded into the small hole between the fibers, and airflow continues to pass through the gap between the fibers. At this time, the filter material becomes effective filter material for both coarse and fine dust particles, and forms the process of collecting dust. In addition, when the diameter of dust in the airflow is smaller than that of fiber, the effects of collision, hook attachment, diffusion and so on increase, and the dust removal efficiency increases.

2) needle felt or needle felt filter material can give full play to the above effect due to its thick porous filter bed, but the filtering effect of "the second filter layer" is still very important.

3) membrane-covered filter material, microporous membrane-covered filter material (hereinafter referred to as membrane-covered filter material) is made of polytetrafluoroethylene as raw material, which is expanded into a kind of microporous film, and the film is coated on various fabrics or paper substrates by special process to make it a new type of filter material.

Polytetrafluoroethylene membrane filter material is composed of polytetrafluoroethylene microporous membrane and various substrates (PPS, glass fiber, P84, aramid fiber) by special composite technology. The surface of the Polytetrafluoroethylene (PTFE) film is smooth and resistant to chemical substances. It is coated on the surface of ordinary filter materials, which plays the role of disposable dust layer. All the dust is intercepted on the surface of the film to realize surface filtration. It has incomparable advantages over traditional filter materials. The coated filter material has the characteristics of high peeling strength, large air permeability, small resistance, concentrated and uniform aperture distribution, etc. As a dust removal cloth bag or pleated dust removal filter cartridge installed in the dust removal equipment, it will quickly and effectively intercept ultra-fine dust calculated in micrometers, and the dust removal efficiency reaches more than 99.99%. It is the most effective and economical new type of filter material in industrial dust filtration and material recovery.

There is a layer of artificial synthetic film on the surface of the film-coated filter material, with a grid structure inside, a thickness of 50 μm and 1.4 billion micropores per cm³. Obviously, its filtering effect is mainly sieve filtration effect, so it is called surface filtration.

2. Reasonable ash cleaning cycle

In the actual operation of the bag filter, with the increase of the dust layer of the filter bag, it is necessary to periodically clear the dust of the filter material. With the constant increase of the amount of dust collected, the dust layer increases continuously, and its filtration efficiency increases with it. The resistance of the dust collector also increases gradually, while the air volume through the filter bag decreases gradually. At this time, the filter bag needs to be cleaned with dust, that is, the dust accumulated on the cloud filter bag should be removed timely and evenly, and excessive dust removal should be avoided to keep the "first dust layer" to ensure stable and high efficiency, this is more important for filter materials with large pores or easy ash removal.