Pneumatic ventilation butterfly valve Pneumatic ventilation butterfly valve is a kind of ventilation butterfly valve. It is mainly used in sintering and smelting systems of metallurgical industry or ventilation and dust removal pipelines of building materials, energy, chemical industry, environmental protection and other industries. It is a safe and reliable regulating and isolating device

Analysis of the reason for the crack of non-metallic fabric compensator:
1. The pouring data in the contraction joint is scattered. During the operation of 300MwCFB boiler, the wear-resistant and fire-resistant casting materials in the contraction joint of non-metallic fabric compensator were scoured and worn by high temperature fuel, fuel ash, limestone and its reaction products, which were prone to crack, deformation, damage and scattering, so that high-temperature flue gas and circulating materials could directly wash the skin outside the non-metallic fabric compensator and burn it through. In the process of some temporary modification and skin replacement, it was found that the pouring materials on both sides of the contraction joint that damaged the contraction joint were seriously scattered, and the aluminum silicate felt filled in it was also all scattered. Especially, the contraction joint of the 3 # return leg of furnace 1 was changed twice within a month. The pouring materials on both sides of the contraction joint were scattered to form a contraction joint with a maximum width of 300 mm. In order to avoid burning through again, The aluminum silicate felt is used to block the contraction joint with heat, and good results are obtained.
2. The design and construction are unreasonable. After one year of boiler operation, during the accident handling process, it was found that the thermal gap of the contraction joint of the non-metallic fabric compensator was about 110 mm (the design gap was 10 mm), which was caused by the excessive gap of the contraction joint (80 mm) when the contraction joint was installed, so that the filling materials (ceramic fiber adhesion) in the contraction joint were washed by high temperature flue gas. In addition, the construction quality of the castables around the contraction joint is poor, and the heat is easy to diffuse from the cracked castables. 3. The bed is seriously overturned. After the boiler seriously overturns the bed, the bed material will be blown from one side of the furnace to the other side, making the bed pressure on one side and the pressure of the water-cooled air chamber high at a high speed. The pressure difference between the two beds is large, and the side where a large amount of bed material is piled up blocks the return leg from the furnace. At this time, the fluidizing air passing through the air cowl and entering the feeder is blocked between the self sealing at the lower part of the return leg and the bed material blocked in the furnace. The pressure of the fluidizing air is 50~55kPa, and the maximum acceptable air pressure designed for the skin of the non-metallic fabric compensator is 30kPa. The fluidizing air roof breaks the skin of the non-metallic fabric compensator, causing smoke to escape, burning the skin of the shrink joint.