Bag filter

Description

Bag filter is a dry dust filter. After the filter material is used for a period of time, due to the effects of screening, collision, retention, diffusion, static electricity, etc., a layer of dust accumulates on the surface of the filter bag. This layer of dust is called the primary layer. In the subsequent movement process, the primary layer becomes the main filter layer of the filter material. Relying on the effect of the primary layer, the filter material with a larger mesh can also obtain a higher filtration efficiency. With the accumulation of dust on the surface of the filter material, the efficiency and resistance of the dust collector increase accordingly. When the pressure difference on both sides of the filter material is large, some fine dust particles attached to the filter material will be squeezed over, causing the efficiency of the dust collector to decrease. In addition, if the resistance of the dust collector is too high, the air volume of the dust removal system will decrease significantly. Therefore, after the resistance of the dust collector reaches a certain value, it is necessary to clean the dust in time. The primary layer must not be damaged during cleaning to avoid a decrease in efficiency.

Working principle

The high dust removal efficiency of the bag filter is inseparable from its dust removal mechanism. When the dust-laden gas enters the ash hopper through the guide plate from the lower air intake pipe of the dust collector, the coarse dust will fall into the ash hopper due to the collision of the guide plate and the reduction of gas velocity, and the remaining fine dust particles will enter the filter bag chamber with the gas. Due to the inertia, diffusion, barrier, hooking, static electricity and other effects of the filter material fibers and fabrics, the dust is retained in the filter bag, and the purified gas escapes from the bag and is discharged through the exhaust pipe. The dust accumulated on the filter bag is removed by gas backwashing, and the removed dust goes down to the ash hopper and is discharged to the ash conveying device through the double-layer ash unloading valve. The dust accumulated on the filter bag can also be removed by blowing pulse airflow to achieve the purpose of cleaning, and the removed dust is discharged by the ash discharge device. The high dust removal efficiency of the bag dust collector is also inseparable from the filter material. The performance and quality of the filter material are directly related to the performance and service life of the bag dust collector. The filter material is the main material for making filter bags. Its performance and quality promote the advancement of bag dust removal technology and affect its application range and service life.
Filter dust removal devices include bag dust collectors and granular layer dust collectors. The former usually uses filter bags made of organic fiber or inorganic fiber fabric as the filter layer, while the latter’s filter layer is mostly composed of particles of different particle sizes, such as quartz sand, river sand, ceramsite, slag, etc. As the powder repeatedly adheres to the outer surface of the filter bag, the powder layer continues to thicken, and the resistance value of the bag dust collector also increases; the pulse valve diaphragm sends a command, and the pulse valve opens when it is flooded on the left and right, and the compressed air in the high-pressure air bag is passed. If there is no dust or it is small to a certain extent, the mechanical cleaning work will stop.