Its sealing form mostly adopts sealing structure, and the sealing material is rubber, PTFE and so on. Due to the limitation of structural characteristics, it is not suitable for industries such as high temperature resistance, high pressure resistance, corrosion resistance and wear resistance. At present, the more advanced butterfly valve is the triple eccentric metal hard seal butterfly valve. The valve body and the valve seat are connected parts, and the sealing surface of the valve seat is covered with heat-resistant and corrosion-resistant alloy materials. Compared with the traditional butterfly valve, this butterfly valve has the advantages of high temperature resistance, easy operation, no friction when opening and closing, compensation sealing with the increase of torque of transmission mechanism when closing, and improved sealing performance and service life of the butterfly valve.
However, this butterfly valve still has the following problems in use:
1. Because the multilayer soft and hard laminated sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium washes its sealing surface, and the soft sealing band in the metal sheet interlayer will directly affect the sealing performance after being washed.
Secondly, due to the structural conditions, this structure is not suitable for making valves with a diameter below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.
Thirdly, due to the principle of triple eccentric structure, the seal between the sealing surface of the valve plate and the valve seat depends on the torque of the transmission device to make the valve plate press on the valve seat. In the forward flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium in the flow channel flows reversely, with the increase of medium pressure, when the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the seal begins to leak.
High Performance Three Eccentric Bidirectional hard seal butterfly valve
It is characterized in that the sealing ring of the valve seat is composed of multiple layers of stainless steel sheets on both sides of the soft T-shaped sealing ring.
The sealing surface between the valve plate and the valve seat is of an inclined conical surface structure, and the inclined conical surface of the valve plate is surfacing with a temperature-resistant and corrosion-resistant alloy material; The spring fixed between the pressure plates of the adjusting ring is assembled with the adjusting bolts on the pressure plates. This structure effectively compensates the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under medium pressure, and solves the sealing problem of the valve in the process of bidirectional exchange of medium transportation.
The sealing ring composed of soft T-shaped stainless steel sheets on both sides has the dual advantages of metal hard sealing and soft sealing, and has zero leakage sealing performance at low temperature and high temperature. The test shows that the pressure on the sealing surface is generated by the torque of the transmission device and the pressure of the medium acting on the valve plate when the pool is in a positive flow state (the flow direction of the medium is the same as the rotation direction of the butterfly plate). When the positive medium pressure increases, the tighter the compression between the inclined conical surface of the valve plate and the sealing surface of the valve seat, the better the sealing effect.
When in the reverse flow state, the seal between the valve plate and the valve seat is pressed against the valve seat by the torque of the driving device. With the increase of the reverse medium pressure, when the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation stored in the adjusting ring spring after loading can compensate the tight pressure between the valve plate and the valve seat sealing surface, which plays an automatic compensation role.
Therefore, different from the prior art, the utility model does not install the soft and hard multilayer sealing ring on the valve plate, but directly installs it on the valve body, and adds an adjusting ring between the pressure plate and the valve seat, which is an ideal two-way hard sealing mode. It will replace Beijing gate valve, Beijing globe valve and ball valve.