Main points and structural characteristics of bag filter:
- The working principle of the bag filter is to use the fabric filter material to separate and capture the dust-containing gas, which has the functions of screening, intercepting and diffusing the dust-containing gas. Among them, screening is the main dust filter function of the bag filter. If the particle size of the dust exceeds the pores of the filter material, the equipment can automatically filter out the dust. Under normal circumstances, if the pores of the fabric filter material are larger than the particle size of the dust, the screening operation is mainly completed by inertial collision and diffusion. If the dust adhesion layer is gradually formed on the filter cloth, the effects of collision and diffusion are reduced, and the deposited dust is mainly filtered by sieving. It must be noted that the filter material and cleaning method are the key contents affecting the dust removal effect of the bag filter. The filter material not only has good air permeability and compactness, but also has good corrosion resistance and high temperature resistance. The dust removal of the bag filter mainly includes mechanical vibration, pulse backflushing and other methods. Pulse backflushing mainly includes high pressure, medium pressure and low pressure pulse backflushing according to the air pressure. Pulse cleaning can effectively adjust the injection intensity and frequency, and is the most widely used and most effective cleaning method in the world.
- The bag filter is mainly composed of filter bag components, ash removal system, offline protection system and other key parts. The dust-laden gas is led to each unit chamber by the guide pipe. Based on the action of the guide device, the large particle dust directly falls into the ash hopper through the separation operation, and other dust gradually enters the different filter areas with the airflow, and then the filtered gas can be discharged. If the dust on the surface of the filter bag reaches a certain thickness, the difference between the inner pressure and the outer pressure of the filter bag will increase significantly. If the pressure difference between the inside and outside rises to the set value, the air in the air tank will force the diaphragm of the pulse valve to open automatically, and the treated air will be output. The air duct is sprayed into the filter bag from the nozzle to implement automatic back blowing operation. The filter bag assembly is mainly composed of two parts: cloth bag and bag cage. The bag cage can effectively support the cloth bag, the upper part is connected with the carbon steel ring, and the cloth bag is buckled and locked on the hole of the filter head plate.
- The dust removal principle of cloth bag and electrostatic precipitator is different, and both have their own advantages and disadvantages. The advantages and disadvantages of the bag filter are as follows: the effect of the bag filter is better (99.9%), especially for the collection of sub-micron dust, and the dust concentration of the flue gas at the outlet of the filter is less than 30mg/m3. At the same time, within a certain range, the dust concentration of the dust collector will not change due to the amount and concentration of the inlet flue gas, so as to ensure that the emission concentration of the smoke and dust is kept at a low state for a long time and meet the requirements of environmental dust removal in the new era. The bag filter has a wide range of dust collection, and is especially suitable for collecting pulverized coal with high ash content and low sulfur content. Corresponding insulation measures must be taken when the bag filter treats dusty gas with high humidity.
