Bag filter is a dry dust removal device, and its working principle is bag filter. When the dusty gas enters the bag filter, the dust with large particles and heavy specific gravity is settled by gravity. Bag filter is made of woven filter cloth or non-woven felt, which is suitable for collecting fine and dry non-fiber dust.

Bag filter filters dust-containing gas by the filtering effect of fiber fabric, and falls into the ash hopper. When the gas containing small dust in bag filter passes through the filter material, the dust is blocked and the gas is purified. In addition, when the pressure difference between the bag filters is large, the bag filters will squeeze some small particles attached to the filter materials, thus reducing the efficiency of the filters.

A layer of dust is accumulated on the surface of the dust bag, which is called the primary layer. In the later movement process, the primary layer becomes the main filter layer of the filter material, and the dust removal efficiency of the new filter material is generally not high enough. After the filter material of bag filter is used for a period of time, due to the effects of screening, collision, retention, diffusion, static electricity and so on, the filter material with larger mesh of bag filter can also obtain higher filtration efficiency.

The performance of bag filter is good or bad. In addition to the correct selection of bag filter material, the filter material with larger mesh can also obtain higher filtration efficiency. When the resistance of bag filter with pleated filter bag reaches a certain value, dust should be removed in time. Bag filter can't damage the initial layer when removing dust, so as to avoid the decrease of efficiency. The structure of bag filter is mainly composed of upper box, middle box, lower box, ash cleaning system and ash discharging mechanism.