Application of filter bag in Steel Industry

There are different working conditions in different processes in iron and steel enterprises, so there are also differences in the selection of filter bags.

Coking. 

The temperature of the coking flue gas is around 90°C, and the instantaneous temperature can reach 130°C. The flue gas contains sulfur and less moisture. According to the different process parts, the performance requirements of the filter bag are also different. For example, coke blocking and dust removal require anti-static and flame retardant, coke table and CDQ dust removal require anti-static, and coke screening and dust removal require waterproof, oil-proof, and anti-static.

Sintering. 

The flue gas of the sintering machine head is generally equipped with dry, semi-dry and wet desulfurization systems after the electric dust removal. The semi-dry desulfurization system needs to be equipped with bag dust removal. According to the flue gas temperature of the sintering machine head after desulfurization (90 ℃ or so) and composition (a small amount of SO2, NOX, dust) use PTFE-coated polyester needle-punched felt as a filter bag. The sintering machine tail, flux, ingredients, and whole-grain dust removal now use electric dust removal for flue gas collection. In order to meet the special emission limit of 20mg/m3, the electric dust removal can be changed to bag dust removal, according to the bag dust removal used for sintering fuel To analyze the emission concentration, use PTFE-coated polyester needled felt as the filter bag, and the emission concentration can be maintained at about 10mg/m3.

Blast furnace ironmaking. 

According to the characteristics of blast furnace flue gas, all blast furnace flue gas environmental dust removal uses waterproof and oil-proof PTFE-coated polyester needle felt as the dust removal filter bag, and the concentration of particulate matter can be controlled within 10mg/m3, which can satisfy the new national air pollution. Special emission limit requirements for blast furnace gas; the main components of blast furnace gas are CO, CO2, N2, H2, CH4, among which the combustible component CO accounts for about 25%. Now dry dust removal is used to purify it, because its continuous operation flue gas temperature reaches 200 Above ℃, high-temperature resistant glass fiber or P84 (polyimide) must be used as the filter material. However, through practical use, the glass fiber filter material is easy to break, has a short life, and cannot ensure long-term filtration accuracy. Therefore, PTFE coated P84 ( Imported from Austria) Needle-punched filter material has a service life of up to 3 years under normal conditions, and the emission concentration of particulate matter is stably controlled at about 3mg/m3, which can completely meet the needs of production.

Electric stove. 

At present, the electric furnace dust removal adopts a three-stage capture method of four holes, a doghouse and a roof cover, which reasonably mixes high-temperature flue gas and normal temperature flue gas, and effectively reduces the temperature of the flue gas at the inlet of the dust collector. However, considering emergencies, the flue gas temperature may reach above 200℃ in an instant. Therefore, the use of PTFE-coated aramid filter media can not only reduce operating costs, but also effectively trap flue gas and filter efficiently to ensure that the particulate matter emission concentration is controlled at 10mg/ m3 or less.

Converter. 

The converter secondary flue gas belongs to the normal temperature scale, and the PTFE coated polyester needle felt is used as the filter bag, and the emission concentration can be maintained at about 10mg/m3, which can meet the new particulate emission concentration requirements.

AOD. 

The AOD refining process is a reductive reaction process. If the furnace body flue gas and roof hood flue gas are separately collected separately, because the temperature of the furnace body flue gas is high and alkaline, and there is water leakage in the water-cooled flue, choose the method The filter material must have the characteristics of waterproof and alkali resistance. PTFE-coated aramid filter material can be selected, which can not only be waterproof, but also has the characteristics of alkali resistance and high temperature resistance. For roof cover dust removal, PTFE coated polyester needle-punched felt is used as the filter bag, which can satisfy the collection and discharge requirements. If you choose the method of mixing furnace flue gas and roof flue gas and then entering a dust collector, because of the mixing effect of room temperature flue gas on the roof, the temperature of the flue gas at the inlet of the dust collector can meet the requirements of room temperature, so choose PTFE coated polyester needle punch Felt can be used as a filter bag.