Bag filter is a dry dust filtering device. Bag filter is suitable for capturing small, dry, and non fibrous dust. The filter bag is made of textile filter cloth or non-woven felt, and uses the filtering effect of fiber fabric to filter the dust containing gas. When the dust containing gas enters the bag filter, the large and heavy dust particles settle down due to gravity and fall into the ash hopper. When the gas containing finer and smaller dust passes through the filter material, the dust is retained and the gas is purified.

Bag filter is a dry dust filtering device. After using the filter material for a period of time, due to screening, collision, retention, diffusion, static electricity and other effects, a layer of dust accumulates on the surface of the filter bag, which is called the initial layer. During the subsequent movement process, the initial layer becomes the main filtering layer of the filter material. With the help of the initial layer, filter materials with larger mesh holes can also achieve higher filtration efficiency. As dust accumulates on the surface of the filter material, the efficiency and resistance of the dust collector increase accordingly. When the pressure difference between the two sides of the filter material is large, some small dust particles that have already adhered to the filter material will be squeezed out, causing a decrease in the efficiency of the dust collector. In addition, excessive resistance of the dust collector can significantly reduce the airflow of the dust removal system. Therefore, after the resistance of the dust collector reaches a certain value, it is necessary to clean the dust in a timely manner. When cleaning, the initial layer should not be damaged to avoid a decrease in efficiency.

The high dust removal efficiency of bag filter is inseparable from its dust removal mechanism. When the dusty gas enters the ash hopper through the lower intake pipe of the dust collector and the guide plate, due to the collision of the guide plate and the decrease in gas velocity, coarse dust particles will fall into the ash hopper, while 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 fiber and fabric, the dust is trapped in the filter bag, and the purified gas escapes from the bag and is discharged through the exhaust pipe. The accumulated dust on the filter bag is removed by gas backwashing method, and the removed dust is discharged to the ash hopper and discharged to the ash conveying device through the double-layer ash discharge valve. The dust accumulation on the filter bag can also be removed by spraying 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 a bag filter is also inseparable from the filter material. The performance and quality of the filter material directly affect the performance and service life of the bag filter. The filtering material is the main material for making filter bags, and its performance and quality promote the progress of bag dust removal technology, affecting its application scope and service life.

The filter type dust removal device includes a bag filter and a particle layer dust collector. The former usually uses filter bags made of organic fibers or inorganic fiber fabrics as the filter layer, while the latter's filter layer is mostly composed of particles of different sizes, such as quartz sand, river sand, ceramic particles, 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 filter also increases accordingly; The pulse valve diaphragm sends a command, and when the left and right sides are submerged, the pulse valve opens, and the compressed air in the high-pressure air bag is opened. If there is no dust or it is small enough, the mechanical dust cleaning work will stop working.

The gas purification method of the low-pressure pulse bag filter is external filtration. The dusty gas enters each unit filtration chamber through a guide pipe. Due to the design, there is sufficient and reasonable airflow from the bottom of the filter bag to the upper opening of the air inlet through appropriate guidance and natural flow distribution, achieving uniform air distribution throughout the filtration chamber. The particulate dust in the dusty gas is separated by natural settling and directly falls into the ash hopper, while the remaining dust is guided by the guide system and enters the middle box filtration area with the airflow, adsorbing on the outer surface of the filter bag. The filtered clean gas passes through the filter bag and is discharged through the upper box and exhaust pipe.

The filter bag uses compressed air for blowing and cleaning, and the cleaning mechanism consists of an air bag, a blowing tube, and an electromagnetic pulse control valve. Each row of filter bags in the filtration room is equipped with a spray pipe at the top of the outlet. The lower side of the spray pipe is directly facing the center of the filter bag and has a spray port. Each spray pipe is equipped with a pulse valve and is connected to the compressed air bag. When cleaning the dust, the electromagnetic valve opens the pulse valve, and the compressed air is sprayed by the dust cleaning control device (differential pressure or timing, manual control) according to the set program to turn on the electromagnetic pulse spray. The compressed gas passes through each pulse valve in a very short time and in sequence through the nozzle on the spraying pipe, inducing several times the amount of air injected into the filter bag, forming an air wave, causing the filter bag to expand rapidly and vibrate violently from the bag mouth to the bottom, resulting in a strong dust cleaning effect and shaking off the dust on the filter bag.