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Analysis on Application principle of Dust layer and Surface Filtration of Dust filter cloth
Mar 15, 2018

Analysis on Application principle of Dust layer and Surface Filtration of Dust filter cloth

The smoke and dust permeate through the surface of the filter cloth, and at the same time the dust is removed by some ways. After the above two actions are balanced, the inner layer of the filter cloth (felt layer) forms a layer of 0.5 to 0.7 mm thick, which is intertwined by dust and filter cloth fibers. This is called the inner filter layer, which is equivalent to the first filtering layer of the plain fabric mentioned above.

Dust filtration mechanism:

In the filtration mechanism of filter material fiber, such as diffusion, gravity, inertial collision, and static electricity and so on, there is a dust layer, but the main one is screening. When the bag filter starts to operate, there is no dust on the new filter bag. After running for a few minutes, a thin dust film is formed on the surface of the filter bag. Because the filter bag is made of fiber, so before the dust layer is formed, Under the effect of diffusion, dust will gradually form the bridging phenomenon between fibers. The diameter of filter bag fiber is 20 ~ 1005 mm, the diameter of needle felt fiber is 10-205 um. the distance between fibers is 10-305 um. the bridging phenomenon is easy to occur. The dust layer of 0.3-0.5 mm after bridging is usually called dust film or primary dust layer. The dust accumulated again above the primary dust layer is called the secondary dust layer. The dust removal efficiency of plain fabric filter cloth itself is 85% ~ 90, and the efficiency is relatively low. But when the dust on the surface of the ladle is deposited, A high dust removal efficiency of more than 99.5% can be obtained. Therefore, it is necessary to leave a dust layer of 0.3-0.5 mm thick on the filter cloth surface after dust removal, so as to prevent the dust removal efficiency from decreasing. The problem lies in how to make the first dust layer retain during the operation of the dust collector. The problem of removing a second dust layer is both a technical problem and a disposal experience for a design manufacturer. So it can be said that the history of a bag dust collector. Based on the effect of dust layer on efficiency, the dust removal efficiency in the dust layer flaking off part of dust layer decreased sharply. At the same time, because of the reduction of pressure loss, the flue gas flow through this part of the dust layer. A few seconds later, the dust layer was formed on the filter cloth surface, and the dust removal efficiency increased again, that is, a certain amount of dust could be discharged from each cleaning cycle.

Surface filtration mechanism

Based on the theory of the formation of dust layer in favor of filtration, a microporous film is artificially coated on the surface of ordinary filter material to improve the dust removal effect. Therefore, the film on the filter surface is also called artificial dust layer. In order to control the capture efficiency of different particles, the pore size of a microporous surface film for different purposes is variable. For example, when filtering ordinary dust, the pore size of a micropore is usually less than 25 ums. When filtering bacteria, the pore size is less than 0.35 um. when filtering a virus, the pore size is less than 0.055 um.This difference is like a sieve hole. According to the demand of screen, the screen screen with different sieve holes is selected. The film of surface filtration can be coated on the surface of ordinary filter material or on the surface of plastic burning board. The film coated on filter cloth before the day is all made of fluoroethylene membrane, and the type of bottom cloth is more than 20 kinds. However, there is only one kind of film, the thickness of the film is about 8-30 um, and the products of different manufacturers are slightly different.








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