The filter bag is the core filter component of the bag filter, and its cost accounts for about 10% to 15% of the equipment cost. The material of the filter bag made of the filter bag directly determines the performance parameters of the bag filter, such as the specifications of the dust removal equipment, dust removal efficiency, emission concentration, operation resistance, service life and other indicators. Therefore, the correct selection of filter bags is very important. The following shares 7 selection principles and 2 types of selection basis, correct selection, and improve dust removal efficiency.


1. The principle of filter bag selection

(1) Reasonable structure and high capture rate;

(2) Good peelability, easy to clean dust, not easy to scale;

(3) Suitable air permeability, low resistance and high filtration accuracy;

(4) It has sufficient strength and good dimensional stability;

(5) It has good temperature resistance, chemical corrosion resistance, oxidation resistance, hydrolysis resistance and wide adaptability;

(6) Wide sources of raw materials, stable and reliable performance;

(7) Low price and long life.


2. Selection basis

(1) Choose according to the characteristics of the filter material

Polyester

Polyester filter media is usually used in places with low temperature. Usually, there is no need to cover it. Only when the emission requirement is less than 30 mg/Nm³, or when the dust is very fine and the humidity is high, the film is considered.


Polytetrafluoroethylene

Polytetrafluoroethylene (PTFE), also known as Teflon, is stretched into a powerful microporous material with a pore diameter of 0.1μm2.0μm and a porosity greater than 80%. It has excellent chemical corrosion resistance. , Sodium hydroxide and uranium pentafluoride, a strong corrosive in the atomic industry, will not corrode, and can withstand cold and heat resistance. It can be used for a long time at -200250, and it has good electrical insulation and smooth surface. Characteristics. Polytetrafluoroethylene filter media is often treated with mulching or needle punching techniques to improve dust removal efficiency and prolong service life.


Nomex

Nomex filter media can be used in applications where the temperature is relatively high and the dust particles are relatively coarse. Nomex has good high temperature resistance and is more resistant to bending than glass fiber. Higher injection pressure can be used, and more filter bags can be injected with the same pulse valve.


Glass fiber

Glass fiber has good high temperature resistance, good tensile resistance, acid and alkali resistance, and water repellency. However, the glass fiber filter material is not resistant to bending, is easily damaged during installation and operation, and cannot be high-pressure cleaning. High requirements and other shortcomings, but under the existing scientific and technological conditions, the glass fiber has undergone good post-processing and the application of film coating technology to make its filtration performance very excellent. It has been widely used in foreign countries, especially in Europe and the United States.

 

(2) Choose according to the nature of dusty gas

Gas temperature

The temperature of dusty gas is an important factor in the selection of filter bags. Generally, the dust-containing gas below 130 is called normal temperature gas, and the dust-containing gas above 130 is called high temperature gas. Therefore, filter bags can be divided into two categories: normal temperature filter bags below 130 and those above 130 High temperature filter bag. For this reason, a suitable filter bag should be selected according to the flue gas temperature. In actual work, some people call 130200 gas as medium temperature gas, but the filter bag is mostly high temperature type.


Gas humidity

Dust-containing gas is divided into three states according to relative humidity: when the relative humidity is below 30%, it is a dry gas, when the relative humidity is between 30% and 80%, it is a normal state, and when the relative humidity is above 80%, it is a high-humidity gas. For high-humidity gas, when it is at a high temperature, especially when SO is contained in dust-containing gas, condensation will occur when the gas is cooled. This will not only cause scale and blockage on the surface of the filter bag, but also corrode the structural materials, so special attention should be paid.


The chemical properties of the gas

In various furnace flue gas and chemical waste gas, there are often many chemical components such as acids, alkalis, oxidants, organic solvents, etc., and they are often cross-influenced by various factors such as temperature and humidity. Therefore, when selecting a filter bag, it is necessary to grasp the main factors and comprehensively consider the chemical composition of the dust-containing gas.


In addition, when selecting a filter bag, the nature of the dust and the dust removal method of the dust collector should also be considered, and the mutual relationship and respective characteristics between them should be matched and selected to ensure that the appropriate filter bag is selected to ensure the quality of dust removal.