Acrylic needle punching felt dust bag, chemically known as polyacrylonitrile, is made of acrylic by needle punching method and then treated with a special water repellent treatment to obtain acrylic medium temperature hydrolysis resistant needle punching filter felt. It is woven with imported fibres and is a medium temperature material with good resistance to acid and alkali and hydrolysis. Needle felts are made of acrylic woven fabric to enhance the longitudinal and transverse strength. It has excellent chemical resistance and hydrolysis resistance, and is widely used in waste incineration, asphalt, dryers, coal mills, power plants and other flue gas dust collection. Acrylic fiber needle-punched filter felt dust bag raw materials imported from abroad, its medium-temperature field heat-resistant, corrosion-resistant high-performance fibers with flame retardant properties. Compared with ordinary acrylic dust bag, it has higher temperature resistance, with a continuous working temperature of 130°C. Compared with polyester (polyester) or other acrylic fibres, it has better alkali resistance and resistance to the corrosion of gases such as SO2, O2 and O3. This acrylic dust bag shows good resistance to organic solvents, oxidisers, inorganic and organic acids at temperatures below 125. It does not hydrolyse, so it is particularly important to replace polyester (polyester) needle felt filter bags with manufactured products at low temperatures where there is chemical corrosion and moisture. Medium temperature acrylic needle felted dust bag is a plain base cloth on a layer of short fibres, with a barbed needle vertically moving up and down the surface of the cloth, with a needle to tie the fibres to the base cloth yarn velvet seam to go, base cloth on both sides are laid two or more fibre layer, repeated needle punching forming, and then by various treatments into two sides with pile needle felted structure of the filter media. Needle felted dust filter media has good filtration effect, low resistance, easy to clean ash, waterproof and oil-proof, anti-condensation and other characteristics after various post-treatment processes.

Acrylic dust bag fiber, it is made from 100% acrylonitrile of the first monomer copolymer, by wet or dry spinning and produced. Close to the flame when the melt shrinkage, contact with the flame when the melt burning, leaving the flame continues to burn and black smoke, burning with burning hair smell, the residue after cooling, lightly twisted by hand is black irregular small beads or scorched carbon, easy to break. (1) acrylic dust bag morphology: its longitudinal surface or a small number of grooves, cross-section varies with different spinning methods, dry spinning fiber cross-section is dumbbell-shaped, wet spinning is round. (2) acrylic dust bag strong elongation and elasticity: its strength of 17.6 to 30.8cN/tex, lower than polyester and nylon, its elongation at break of 25% to 46%, similar to polyester, nylon. Acrylic fluffy, curly and soft, elasticity is better, but the residual deformation of multiple stretching is larger, the fabric is not good conformability. (3) acrylic dust bag moisture absorption: acrylic structure is tight, low moisture absorption, general atmospheric conditions moisture regain rate of about 2%. (4) acrylic dust bag light resistance: acrylic light resistance and weather resistance is particularly good, the best in the common textile fibers. Acrylic in outdoor exposure to the sun for a year, its strength only 20% decline, so acrylic is most suitable for outdoor fabrics. (5) Acrylic dust bag acid and alkali resistance: it has a good chemical stability, acid resistance, resistance to weak alkali, oxidizing agents and organic solvents. However, acrylic will yellow in the alkali solution, macromolecules fracture. (6) Acrylic dust bag of other properties It has good heat resistance, but poor abrasion resistance and poor dimensional stability. The relative density of acrylic is small. Acrylic dust bag working use temperature ≤ 150 ℃, the instantaneous temperature ≤ 180 ℃. Dust bag is generally divided into three main categories, namely room temperature, medium temperature, high temperature filter bag type. Normal temperature dust removal filter bags generally work below 120 ℃, mainly polyester type filter bags; medium temperature dust removal filter bags generally work below 150 ℃

To understand the P84 bag selection, you first need to know the chemical characteristics of P84 dust bag: P84 chemical structure is: polyimide. Has excellent resistance to sulfur oxides, nitrogen oxides, alkali resistance is relatively good, more suitable for use in acid, alkali corrosion of the place. Temperature characteristics:P84 is more sensitive to temperature and is generally required to operate at a temperature of 150 - 260 degrees Celsius. Structural characteristics:Triple leaf type structure, large specific surface area, and wear-resistant, high filtration efficiency. The selection of dust bags should be based on the nature of the flue gas to be treated, the overall structure of the dust removal equipment and the performance of the integrated dust bags, thus forming a reasonable and optimised solution. 1. Nature and temperature of the flue gas (1) Temperature working temperature (continuous working temperature, instantaneous working temperature) Dew point temperature; (2) Chemical properties (acidic, alkaline, oxidising, hydrolytic) (3) Dust concentration (4) Filtration air speed 2. Dust properties (viscosity, humidity, particle size distribution, flame retardant requirements) 3. Dust cleaning factors (pulse cleaning , dust cleaning pressure) 4. System air leakage rate (oxygen content) Due to the good temperature resistance of P84 fibres, the anisotropic cross-section of the trilobal type (relatively large specific surface area), the high strength of the fibres and the oxidation resistance, the instantaneous temperature resistance of the rate material can be improved, the filtration efficiency improved and the load tolerated improved. Disadvantages: But in actual use, the performance of the indicators of improvement due to the use of the proportion of P84 material restrictions (generally 10% ~ 15% or so), there is no significant improvement, coupled with the poor hydrolysis resistance of P84, so the use is not very wide. P84 dust bag is recommended to be used in working conditions where the concentration of dust is high and the moisture content is low. P84 dust bag features: shaped fibres, large specific surface area, good chemical resistance, medium hydrolysis resistance. P84 dust bag is more expensive and is mainly used for dust collection at the end of kilns above 5000T/D. It can be used for four years normally.

The main process of needle punching non-woven filter material for dust removal bags is: shredding - mixture - further shredding - combing - laying - needle punching - finishing - cuttng. The fibres opened by the bale opener, although much looser compared to the fibre bales, do not yet meet the requirements of uniformity of mixing and openness and require further mixing and opening of the raw material with the blending box. The purpose of the blender is to fully open and mix the raw material. Mixing box form according to the configuration and form of different equipment, generally divided into large bin mixers, multi-bin mixers and semi-automatic mixers. The large bin mixer is to open the bale of fibres after the bale opener, under the action of the fan through the pipe to send fibres to the cyclone separator outlet at the top of the storage bin, the fibres rotate 360° under the action of the rotating wind at the outlet, and at the same time do reciprocal movement along the longitudinal centre of the storage bin, the fibres sprayed out are evenly thrown in layers and piled up. Yuanchen Technology always pays attention to the quality of the product first and puts quality first, and has invested in the production of needle-punched filter media by introducing the advanced needle-punching production line from Autefa, Germany. The production line is equipped with two large bin mixers to achieve sufficient mixing of the upper and lower layers of the filter material respectively, so as to prepare for the final product quality.

Carbon based denitrification catalysts have attracted much attention in recent years due to their excellent thermal conductivity, well-developed pores, huge specific surface area and stable chemical properties, which provide better reaction conditions in SCR reactions, and have been used as carriers for denitrification catalysts by an increasing number of researchers. Carbon based carriers mainly include activated carbon (AC), carbon nanotubes (CNTs), activated carbon fibres (ACF), etc. Wu, Haimiao et al[32] loaded transition metal components such as Fe, Cr, Cu and Mn onto the activated carbon carrier by impregnation method, and the Mn(8%)/AC denitrification catalyst showed the highest denitrification efficiency (95%) at a temperature of 210°C. The Mn(8%)-Fe(8%)/AC denitrification catalyst had the most stable performance and the best catalytic denitrification efficiency. Yoshilawa et al[33] used The Mn2O3/ACF denitrification catalyst was prepared by Yoshilawa et al [33] using ACF as the carrier and Mn2O3 as the active component. The activity evaluation showed that the NO conversion rate could reach about 92% when the loading of Mn2O3 was 15% and the application temperature was 150°C. MnOx/AC denitrification catalysts were prepared by impregnation method, and the experimental results showed that the NO conversion on the denitrification catalysts could reach more than 90% at below 200 °C. Moreover, the activity of the denitrification catalysts was significantly improved when Ce elements were doped in the MnOx/AC denitrification catalysts. Liu Qing et al [12] prepared MnOx-CeO2/PPSN denitrification catalysts by loading MnOx-CeO2 onto nitric acid-treated polyphenylene sulfide (PPSN) filter media using ultrasonic method; They also loaded Mn-Fe onto the active AFC [13] and achieved a NO conversion of 92% at a temperature of 200 °C. The MxOy/MWCNTs (M=Mn, Ce) series denitrification catalysts were prepared by isovolume impregnation using multi-walled carbon nanotubes (MWCNTs) pretreated with oxygen plasma as carriers. Tian et al [36] prepared different denitrification catalysts using nanotubes, nanorods and nanospheres as carriers and MnO2 as the active component, and investigated the effect of different carbon-based carriers on the catalytic activity of denitrification catalysts. Although the charcoal-based carriers have high catalytic activity, they are prone to spontaneous combustion when the flue gas temperature is high, which limits the use of charcoal-based denitrification catalysts.

The results of recent studies have shown that the resistance to H2O and SO2 poisoning of low-temperature SCR denitrification catalysts is an important factor affecting their lifetime, and the resistance to H2O and SO2 poisoning of the currently produced SCR denitrification catalysts still needs to be improved. Kangm et al [11] investigated the SCR activity of MnOx denitrification catalysts prepared with ammonium carbonate, potassium carbonate, sodium carbonate, ammonia, sodium hydroxide and potassium hydroxide as precipitating agents using Mn(NO3)2˙xH2O as the precursor of MnOx. The results showed that carbonate was superior to alkali, sodium salt was superior to potassium salt and ammonium salt as precipitating agents; MnOx denitrification catalysts prepared with sodium carbonate as precipitating agent The MnOx denitrification catalyst prepared with sodium carbonate as precipitant showed high catalytic denitrification activity (over 90% denitrification efficiency) at low temperatures (100-200°C) due to its high specific surface area and amorphous crystalline structure. Although the one-component MnOx denitrification catalyst has the advantages of high catalytic efficiency and low reaction temperature, the one-component denitrification catalyst has certain sintering phenomenon in the preparation process, which affects the dispersion and specific surface area of the denitrification catalyst; in addition, the denitrification catalyst has poor N2 selectivity at low temperature, and the resistance to H2O and SO2 poisoning is not strong, and it is easy to be deactivated in the flue gas environment. In addition, the catalyst has poor N2 selectivity at low temperatures and is not very resistant to H2O and SO2 poisoning. Elemental doping is one of the effective ways to solve these problems. Elemental doping is the doping of other metallic elements into the single component MnOx denitrification catalyst to produce a composite Mn-based denitrification catalyst. On the one hand, this method can effectively reduce the sintering of the active metal during the preparation of denitration catalysts and improve the dispersion and specific surface area of the active metal in denitration catalysts; on the other hand, the added metal atoms can form solid solutions or new crystalline phases with the MnOx [12-13], resulting in a synergistic effect that is beneficial to improving the denitration catalyst activity. The representative elements used for the preparation of MnOx denitrification catalysts are Ce, Fe, Cu, Zr, W, etc. Yang et al [14] prepared an Fe-Mn composite denitrification catalyst by co-precipitation method with good low-temperature catalytic activity and N2 selectivity. Kang et al [16] prepared a non-loaded Cu-Mn composite denitrification catalyst with nearly 100% NO conversion at 50-200 °C. Long et al [17] prepared three oxide denitrification catalysts, Mn-Fe, Mn-Zr and Mn-Fe-Zr, which were evaluated at 100-180 °C. The low-temperature catalytic performa...