Type of filter bags for blast furnace flue gas
Blast furnace flue gas filter bags are mainly made of two kinds of filter materials: woven filter rolls and needle punched fiber felt filter rolls.
Woven filter is made of weaving machine, which has the characteristics of high strength, good wear resistance, high pressure, stable size, smooth surface and ash.
The needle punched felt fiber filter material is made by pricking one or more fibers on the base cloth and then processed and processed. It has the advantages of high porosity, high filtration precision and can compound many kinds of fiber filter material. Fiber filter material is currently used by most of the dust removal industry in blast furnace.
The above two kinds of filter materials can construct a layer of microporous membrane on the surface of fiber filter material, that is, film covering. At present, polytetrafluoroethylene is usually used to cover the film. The filter material has excellent properties such as water repellent and corrosion resistance, corrosion resistance and so on, and the surface smoothness is strengthened, the friction coefficient is reduced, and ash cleaning is easy.
At present, filter material and laminated filter materials used for purifying fume of blast furnace gas are mainly as follows:
-nomex filter bags
Nomex fiber filter (nomex filter bag) belongs to the interposition aramid fiber. It is a non thermoplastic fiber. The fiber filter material can be carbonized or decomposed into small molecules at high temperature when it is used to treat industrial dust smoke. It can withstand the operating temperature of 200 degrees C in the dry environment. It has excellent temperature resistance, flame retardancy and dimensional stability; Nomex needled felt is hydrolytic, and will soon be damaged by hydrolysis in high temperature with chemical medium and water, and the operating temperature is 190 degrees C under the condition of weak acid, neutral and water volume fraction of 10.
-P84 filter bags
P84 filter bag is a kind of synthetic fiber filter material with high temperature resistance. Its irregular blade profile is 80% more surface area than that of general circular section fiber. P84 needle felt can be used continuously below 240 centigrade. It has a certain degree of hydrolysis, and has excellent chemical corrosion resistance.
-fiberglass filter bags
Fiberglass filter bag is a kind of inorganic fiber filter material, its main component is SiO2. Generally, medium alkali glass is melted from molten state and quenched rapidly after melting at 1300-1600 C. The most prominent advantage of glass fiber needle felt fiber filter material is high temperature resistance, long temperature resistance 260 C, and instantaneous temperature resistance to 300 degrees C. Good stability, strong chemical resistance and low price. The drawback is poor folding resistance.
-PTFE filter bags
Polytetrafluoroethylene (PTFE filter bag), or PTFE, is used as the film to prevent filter material. PTFE coated filter fabric filter fiber is the most stable chemical property in all fiber filter materials at present. It can withstand high temperature and can work at high temperature at 240 degrees C for a long time, resistant to various acid and alkali strong oxidizing substances, almost nonflammable, hydrolytic stability and resistance. Good combustion property, known as "non aging fiber", is the first choice for high temperature filtration industry. When used as film mulching, it is used to improve the performance and life of fiber filter media.
The selection of fiber filter material for blast furnace gas can select the most suitable fibrous filter material according to the actual working condition of the blast furnace. The composite fiber filter material with excellent comprehensive properties can be used to improve the service life of fiber filter media and reduce maintenance and operation costs.
