Selection:
The butterfly plate of the butterfly valve is installed in the diameter direction of the pipe. The butterfly valve has a simple structure, small size, light weight, only a few parts, and only needs to rotate 90° to quickly open and close, the operation is simple, and the valve has good fluid control characteristics. When the butterfly valve is in the completely open position, the thickness of the butterfly plate is the resistance of the medium when it flows through the valve body, so the pressure drop that occurs through the valve is very small, so it has good flow control characteristics.
If butterfly valves are required to be used as flow control, the main thing is to select the correct size and type of valve. The structural principle of the butterfly valve is particularly suitable for the manufacture of large-diameter valves. There are two commonly used butterfly valves: clamp-type butterfly valve and flanged butterfly valve. The clamp butterfly valve is to connect the valve between the two pipeline flanges with stud bolts, and the flanged butterfly valve is a valve with a flange, and the upper two ends of the valve are connected to the pipeline flange with bolts.
As a component used to complete the on-off and flow control of the pipeline system, the butterfly valve has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower, etc. In the well-known butterfly valve skills, its sealing form is mostly a sealing structure, and the sealing materials are rubber, PTFE, etc. Because of the limitation of structural characteristics, it is not suitable for high temperature resistance, high pressure, corrosion resistance, wear resistance and other occupations.
At present, a relatively advanced butterfly valve is a three-biased metal hard seal butterfly valve, the valve body and the valve seat are conjoined components, and the outer surface of the valve seat seal is welded with temperature-resistant and corrosion-resistant alloy materials. The multi-layer soft-stacked sealing ring is fixed on the valve plate, this butterfly valve has high temperature resistance compared with the traditional butterfly valve, easy to operate, no conflict between opening and closing, and the torque of the transmission organization increases to compensate for the seal, which improves the sealing performance of the butterfly valve and the advantages of extending the service life.
However, there are still the following problems in the application process of this butterfly valve:
1. Because the multi-layer soft and hard stacked sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium forms a frontal scouring of its sealing surface, and the soft sealing belt in the metal sheet interlayer is directly affected by the erosion.
2. Limited by structural conditions, the structure is not suitable for valves with diameters below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.
3. Due to the principle of the three-bias structure, the sealing between the sealing surface of the valve plate and the valve seat is to press the valve plate to the valve seat by the torque of the transmission device. In the positive flow condition, the higher the pressure of the medium, the tighter the sealing and kneading. When the medium in the runner is reversed, with the increase of the medium pressure, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, and the seal begins to leak.
Three-way bidirectional hard seal butterfly valve, it is characterized in that: described valve seat sealing ring is made up of multiple layers of stainless steel sheet on both sides of soft T-shaped sealing ring. The sealing surface of the valve plate and the valve seat is an oblique cone structure, and the temperature-resistant and corrosion-resistant alloy materials are surfacing on the surface of the oblique cone of the valve plate; A structure in which the tension spring fixed between the conditioning ring pressure plate and the conditioning bolt on the pressure plate are assembled together.
This structure effectively compensates for the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under medium pressure, and deals with the sealing problem of the valve in the process of two-way interchangeable media transportation. The soft T-type is composed of multi-layer stainless steel sheets on both sides of the sealing ring, which has the advantages of metal hard sealing and soft sealing, and has zero leakage sealing performance regardless of low temperature and high temperature.
The test proves that when the tank is in the positive flow condition (the direction of movement of the medium is the same as the direction of rotation of the butterfly plate), the pressure of the sealing surface is caused by the torque of the transmission device and the effect of the medium pressure on the valve plate. When the pressure of the forward medium increases, the tighter the kneading of the oblique cone surface of the valve plate and the sealing surface of the valve seat, the better the sealing effect. In the case of reverse flow, the seal between the disc and the seat is pressed against the seat by the torque of the actuator. With the increase of the pressure of the reverse medium, when the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation energy stored by the tension spring of the conditioning ring after loading can compensate for the tight pressure of the sealing surface of the valve plate and the valve seat to play an automatic compensation role. Therefore, the utility model discloses not like the existing skill, on the valve plate is to be provided with a soft and hard multi-layer sealing ring, but is directly installed on the valve body, and the conditioning ring is very ideal two-way hard sealing mode is added in the middle of the pressing plate and the valve seat. It will replace gate valves, globe valves and ball valves.
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