Introduction of filter cloth used for bag filter

The filter cloth used in the bag filter is made of natural fiber, synthetic fiber and inorganic fiber. 

The filter cloth is divided into three types of woven cloth, non-woven cloth and composite cloth according to the processing method. 

The "208" polyester flannel, needle felt, "729" filter cloth and glass fiber filter cloth commonly used in dust removal engineering and these cloths are coated Filter cloth etc. 

(1) The characteristics of glass fiber filter cloth a and glass fiber filter cloth of Bag Type Dust Collector: high mechanical strength and breaking strength are generally above 1300N; elongation is low, and the elongation at break of glass sewing is only 3%. The filter bag is stable in size; good temperature resistance, can be used for a long time below 260 ℃; good corrosion resistance, can be used in acid and alkali gases; smooth surface, good permeability, poor resistance to abrasion. Surface treatment is the main process in the production of glass fiber woven fabrics, the purpose is to improve its heat resistance, abrasion resistance, folding resistance, corrosion resistance and other properties. There are two general treatment methods: dipping yarn treatment (called pre-treatment) and dipping cloth treatment (called post-treatment). Among them, the dipping solution can penetrate the strands of the plied yarn along the gap during the dipping treatment, and the coating is uniform , But the cost is higher than the dipping method. The surface treatment technology of glass fiber woven fabric has experienced four generations. The first generation, silicone (silicone) treatment, after treatment, the filter material has lubricity, reducing damage caused by deflection, and improved dust exfoliation; the second generation, silicone, polytetrafluoroethylene resin treatment, Improve the heat resistance of the filter material by 20 ～ 30 ℃; The third generation is treated with silicone, polytetrafluoroethylene and graphite. After treatment, the heat resistance of the filter material can be used continuously at 280 ℃. The alkali resistance and acid resistance have also been improved. The fourth generation, with special resin as the matrix, has improved chemical resistance and dust stripping performance. b. Glass fiber bulked yarn filter cloth The glass fiber bulked yarn is made of soft fiber, expanded, and slightly three-dimensional structure by the puffing process, so that the glass fiber cloth has the advantages of high strength of long fibers and bulkiness of short fibers. . In addition to high temperature resistance and corrosion resistance, the filter cloth has the characteristics of good air permeability and high purification efficiency. c. Glass fiber needle felt filter cloth Glass fiber needle felt filter cloth is a new type of high temperature resistant filter material with reasonable structure and excellent performance. It not only has the advantages of high temperature resistance, corrosion resistance, stable size, small elongation and shrinkage, and high strength of the glass fiber fabric, but also the felt layer is single fiber (fiber diameter is less than 6um), three-dimensional microporous structure, high void rate (up to 80% ), Low resistance to gas filtration, is a high-speed, efficient high-temperature pulse filter material. The filter cloth is suitable for high temperature flue gas filtration in industrial furnaces such as chemical industry, steel, metallurgy, carbon black, cement, garbage incineration, etc. The characteristics of glass fiber needle felt filter cloth. 

(2) In addition to the glass fiber filter, the high-temperature needle-punched felt filter cloth of the bag type dust collector, in addition to 'E l, the high-temperature filter cloth used by Cheng also includes aramid needle-punched felt, P84 needle-punched felt, Laitong needle-punched felt Nomex needle punched felt, aramid needle punched felt, carbon fiber composite needle punched felt, Flumes needle punched felt, etc., among which Nomex filter cloth is used more. The material cost of high-temperature filter cloth is generally high, and the price of filter cloth is expensive. Therefore, the service life of filter cloth should be paid enough attention. The application shows that the main factors of filter bag failure are improper filter material selection or improper processing, mechanical abrasion, chemical attack, high temperature melting, dew condensation, etc. 

(3) The membrane filter cloth of bag filter is compounded by two or more kinds of filter materials with different characteristics, called composite filter cloth. The membrane filter cloth made of microporous film on the surface of the needle-punched filter material or the woven filter cloth can realize surface filtration, so that the dust only stays on the surface and is easy to fall off, that is, the peelability of the filter material is improved. The initial group force of this filter material is slightly increased compared with that before the coating, but after the dust collector is operated, due to the good dust stripping and easy cleaning, when the working conditions are stable, the resistance of the filter material no longer rises and tends to be stable, which is significantly lower For conventional filter cloth without membrane. Due to the different materials used for the composite filter cloth and the performance requirements of the product, the processing method of the composite filter cloth is bonded with an adhesive and hot-pressed; if the fiber is thermoplastic, the film and the filter material (substrate) can be laminated and then hot-pressed The machine is directly heated and pressed to make it bond; if the fiber is non-thermoplastic, it needs pretreatment. Membrane filter cloth is a PTFE microporous filter membrane, and the filter material formed by combining with different substrates is composed of two materials. The surface layer of the membrane filter material is very thin, smooth and micro-porous; it has excellent chemical stability, strong toughness, small pore size, high porosity, corrosion resistance, acid and alkali resistance, no aging; coefficient of friction Very low, non-sticky and wide operating temperature (180 ～ 260 ℃). There are dozens of substrates for making membrane filter materials, among which there are dozens of fibers or tissue structures that are existing conventional fabric filter cloths. The variety of substrates is to make the membrane filter material adapt to various temperatures and chemical environments. The pore size of DGF series picture membrane filter cloth is 0.5um, 1um and 3um (generally mean average pore size), to adapt to different sizes of dust and materials. The membrane-coated filter cloth has excellent performance. The filtration method is membrane surface filtration, and nearly 100% of the filtered material is retained. With the increasing requirements for environmental protection, more and more precision filtration, membrane-coated filter materials become dust and materials New materials for filtration and collection and precision filtration. 

(4) "208" polyester velvet cloth of bag filter "208" polyester velvet cloth uses polyester yarn as raw material, and after weaving into filter cloth, it is brushed to form a layer of dense fluff on the surface of the fabric to improve the filtration of the filter cloth. Wear resistance and breathability. The main performance of "208" polyester flannel, this flannel is mostly used for small bag dust collector. 

(5) The needle-punched felt of bag-type dust collector is produced by non-woven needle punching method. Needles are stabbed with fibers staggered in space, and are made through a series of processes such as heat setting and calendering to form a three-dimensional space structure, which is smooth and smooth. The characteristics of needle punched felt: large porosity, good air permeability, reduced pressure loss and energy consumption; high purification efficiency; long service life; wear resistance, corrosion resistance, and strong chemical stability. 

(6) The structure of bag filter "729" filter cloth "729" filter cloth has the characteristics of smooth and soft, high strength, low elongation, low operating pressure loss, good cleaning performance, long service life, etc., after heat setting After being treated by other methods, it is widely used in industrial dust catching and soot control. "729" series polyester filter material is suitable for low-energy dust bag type dust collector. It can be used for a long time in the working environment below 120 ℃ and above the flue gas dew point temperature. It can withstand 130 ℃ in a short time; when filtering high moisture content or When there is a small amount of oily dust, you can use 729-E filter material treated with water-repellent and oil-repellent water. "729" filter cloth is mostly used in conjunction with large-scale anti-blowing bag filter.