Mechanical seal for metal corrugated pipe of medium-pressure butterfly valve in pressurized water reactor nuclear power station

Abstract

The utility model relates to a metal corrugated pipe mechanical seal of a medium-pressure butterfly valve in a pressurized water reactor nuclear power station, which belongs to the technical field of mechanical seals of medium-pressure butterfly valves and comprises a shaft sleeve, a shaft sticking device assembly, a compression ring, a non-compensation ring, a gland, a connecting seat, a corrugated pipe assembly, an auxiliary spring, a compensation ring seat and a compensation ring. The shaft sleeve is used for being arranged on a valve rod of the medium-pressure butterfly valve in a sleeving mode so as to rotate along with the valve rod of the medium-pressure butterfly valve, the pressing ring is arranged on the shaft sleeve, the non-compensation ring is arranged between the pressing ring and the shaft sleeve, the gland is used for being connected with a valve body of the medium-pressure butterfly valve, the connecting base is arranged on the gland, and the auxiliary spring and the corrugated pipe assembly are arranged between the connecting base and the compensation ring base. The compensation ring is arranged on the side, close to the non-compensation ring, of the compensation ring base, and the adjacent end faces between the compensation ring and the non-compensation ring abut against each other to form a friction pair serving as a sealing face. The low-leakage butterfly valve has the effect of meeting the low-leakage working requirement of the medium-pressure butterfly valve in the pressurized water reactor nuclear power station under the operation working condition.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of mechanical seals of medium-pressure butterfly valves, in particular to a metal bellows mechanical seal of a medium-pressure butterfly valve of a pressurized water reactor nuclear power plant. BACKGROUND

[0002] The pressurized water reactor nuclear power plant is a nuclear power plant using the pressurized water reactor technology as the reactor core, and is the main force in the current nuclear power industry due to the maturity and high safety of the technology. The medium-pressure butterfly valve is a key equipment of the steam loop of the pressurized water reactor nuclear power plant, and the nominal pressure PN thereof is 2.5 MPa-6.4 MPa.

[0003] In order to constitute the pressure boundary of the steam loop of the pressurized water reactor nuclear power plant, prevent the overheat steam from leaking to the atmospheric side, and avoid the steam from entering the valve rod bearing chamber, the mechanical seal is usually arranged on the medium-pressure butterfly valve. At present, the medium-pressure butterfly valve mainly adopts the soft seal or the metal seal, and the mechanical seals of the two cannot meet the low-leakage working requirement of the medium-pressure butterfly valve of the pressurized water reactor nuclear power plant under the operating condition. CONTENT OF THE UTILITY MODEL

[0004] In order to help meet the low-leakage working requirement of the medium-pressure butterfly valve of the pressurized water reactor nuclear power plant under the operating condition, the application provides a metal bellows mechanical seal of a medium-pressure butterfly valve of a pressurized water reactor nuclear power plant.

[0005] The metal bellows mechanical seal of the medium-pressure butterfly valve of the pressurized water reactor nuclear power plant provided by the application adopts the following technical scheme:

[0006] The metal bellows mechanical seal of the medium-pressure butterfly valve of the pressurized water reactor nuclear power plant comprises a shaft sleeve, a shaft holder assembly, a pressing ring, a non-compensation ring, a gland, a connecting seat, a bellows assembly, an auxiliary spring, a compensation ring seat and a compensation ring, the shaft sleeve is used for sleeving on the valve rod of the medium-pressure butterfly valve to rotate with the valve rod of the medium-pressure butterfly valve, the shaft holder assembly is used for connecting the shaft sleeve on the valve rod of the medium-pressure butterfly valve, the pressing ring is arranged on the shaft sleeve, the non-compensation ring is arranged between the pressing ring and the shaft sleeve, the gland is used for connecting with the valve body of the medium-pressure butterfly valve, the connecting seat is arranged on the gland, the compensation ring seat is located on the side of the connecting seat close to the non-compensation ring, the auxiliary spring and the bellows assembly are arranged between the connecting seat and the compensation ring seat, and the compensation ring is arranged on the side of the compensation ring seat close to the non-compensation ring. The end faces of the compensation ring and the non-compensation ring in close proximity abut to form a friction pair as a sealing surface.

[0007] Preferably, the distance from the bellows assembly to the valve rod axis of the medium-pressure butterfly valve is less than the distance from the auxiliary spring to the valve rod axis of the medium-pressure butterfly valve.

[0008] Preferably, the bellows assembly is a high nickel-based alloy.

[0009] Preferably, the non-compensation ring is a 304 base plus a surfacing Stellite alloy.

[0010] Preferably, the compensation ring is carbon graphite.

[0011] Preferably, the shaft sleeve, the compression ring, the connecting seat, the compensation ring seat and the compression cover are all made of martensitic stainless steel.

[0012] Preferably, the compression cover is provided with a compression cover sealing ring for improving the sealing performance between the compression cover and the medium-pressure butterfly valve body.

[0013] Preferably, the shaft sleeve comprises a plurality of shaft sleeve units connected in sequence along the axial direction of the medium-pressure butterfly valve stem, the shaft holder assembly is used for fastening the shaft sleeve units to the medium-pressure butterfly valve stem, and a shaft sleeve sealing ring is arranged between adjacent shaft sleeve units.

[0014] Preferably, the compression cover sealing ring and the shaft sleeve sealing ring are both flexible graphite sealing rings.

[0015] Preferably, the shaft holder assembly is made of 17-4PH stainless steel.

[0016] In summary, the present application has the following beneficial technical effects:

[0017] The elastic compensation structure formed by the cooperation of the auxiliary spring and the bellows assembly does not need to set a secondary seal between the compensation ring seat and the connecting seat, and the bellows assembly has excellent anti-interference capability, which can not only adapt to the vibration and impact caused by the opening and closing of the valve, but also can provide continuous axial pressure to ensure the adhesion of the friction sealing end face, thereby ensuring a low leakage rate, which helps to meet the low leakage requirement of the medium-pressure butterfly valve in the operation of the pressurized water reactor nuclear power plant. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic diagram of the overall structure of the embodiment of the present application.

[0019] Explanation of reference signs: 1, shaft sleeve; 2, shaft holder assembly; 3, compression ring; 4, non-compensation ring; 5, compression cover; 6, connecting seat; 7, bellows assembly; 8, auxiliary spring; 9, compensation ring seat; 10, compensation ring; 11, compression cover sealing ring; 12, shaft sleeve sealing ring. DETAILED DESCRIPTION

[0020] The present application will be further described in detail below. Figure 1 The present application will be further described in detail below.

[0021] The embodiment of the present application discloses a medium-pressure butterfly valve metal bellows mechanical seal for a pressurized water reactor nuclear power plant. Referring to Figure 1, the metal bellows mechanical seal of the medium pressure butterfly valve of the pressurized water reactor nuclear power plant is used in the medium pressure butterfly valve of the pressurized water reactor nuclear power plant, and specifically comprises a shaft sleeve 1, a shaft holder assembly 2, a pressing ring 3, a non-compensation ring 4, a gland 5, a connecting seat 6, a bellows assembly 7, an auxiliary spring 8, a compensation ring seat 9 and a compensation ring 10, the shaft sleeve 1 is used for being fixedly sleeved on the valve rod of the medium pressure butterfly valve of the pressurized water reactor nuclear power plant to rotate with the valve rod of the medium pressure butterfly valve, the shaft holder assembly 2 is used for fastening the shaft sleeve 1 on the valve rod of the medium pressure butterfly valve, and the specific structure of the shaft holder assembly 2 is not described here in detail because it is the prior art. The pressing ring 3 is fixedly arranged at the end of the shaft sleeve 1 through bolts, the non-compensation ring 4 is located between the pressing ring 3 and the shaft sleeve 1, specifically, one side of the non-compensation ring 4 in the axial direction of the valve rod of the medium pressure butterfly valve abuts against the pressing ring 3, and the other side abuts against the shaft sleeve 1, the non-compensation ring 4 is tightly abutted against the shaft sleeve 1 through the pressing ring 3, so that the non-compensation ring 4 can rotate with the shaft sleeve 1.

[0022] Referring to Figure 1 The gland 5 is used for fixedly connecting with the valve body of the medium pressure butterfly valve of the pressurized water reactor nuclear power plant, and the gland 5 is relatively fixed during use; the connecting seat 6 is fixedly arranged on one side of the gland 5 close to the non-compensation ring 4 through bolts, the connecting seat 6 comprises a plurality of seat bodies fixedly connected to the gland 5, the shapes and structures of the plurality of seat bodies can be set as required, the compensation ring seat 9 is fixedly connected to one side of the seat body of the connecting seat 6 close to the non-compensation ring 4, the auxiliary spring 8 and the bellows assembly 7 are arranged between the connecting seat 6 and the compensation ring seat 9, specifically, the bellows assembly 7 is in the structure of bellows, the auxiliary spring 8 and the bellows assembly 7 are both connected to the connecting seat 6 at one end and connected to the compensation ring seat 9 at the other end, the auxiliary spring 8 is distributed in multiple along the circumference of the shaft sleeve 1, the compensation ring 10 is fixed to one side of the compensation ring seat 9 close to the non-compensation ring 4, and the end surfaces of the compensation ring 10 and the non-compensation ring 4 abut against each other to form a friction pair as a sealing surface.

[0023] During the rotation of the valve rod of the medium pressure butterfly valve, the shaft sleeve 1, the shaft holder assembly 2, the pressing ring 3 and the non-compensation ring 4 rotate together with the valve rod, while the gland 5, the connecting seat 6, the bellows assembly 7, the auxiliary spring 8, the compensation ring seat 9 and the compensation ring 10 are relatively fixed with the valve body of the medium pressure butterfly valve, so that the friction seal is formed between the compensation ring 10 and the non-compensation ring 4; in the application, the elastic compensation structure of the auxiliary spring 8 and the bellows assembly 7 is adopted, a secondary seal does not need to be arranged between the compensation ring seat 9 and the connecting seat 6, and the bellows assembly 7 has excellent anti-interference ability, can not only adapt to the vibration and impact caused by the opening and closing actions of the valve, but also can provide continuous axial pressure to ensure the adhesion of the friction sealing end surface, thereby ensuring a low leakage rate, helping to meet the low leakage working requirement of the medium pressure butterfly valve of the pressurized water reactor nuclear power plant under the operating condition. Meanwhile, the integrated structure is adopted, the disassembly and assembly are simple, and measurement and debugging are not needed during installation, so that the maintenance speed can be greatly improved, and the working state after sealing installation is consistent with the design state.

[0024] With reference to Figure 1 , specifically, the distance from the bellows assembly 7 to the medium-pressure butterfly valve stem axis is less than the distance from the auxiliary spring 8 to the medium-pressure butterfly valve stem axis, that is, the bellows assembly 7 and the auxiliary spring 8 are arranged in sequence in a direction away from the medium-pressure butterfly valve stem axis, which can ensure that the compensation ring seat 9 has a continuous axial pressure on the side close to the medium-pressure butterfly valve stem, further ensuring the fit of the sealing surface.

[0025] With reference to Figure 1 , the bellows assembly 7 is a high-nickel-based alloy, which refers to an alloy composed of nickel as a matrix and other elements, has good thermal stability, high-temperature strength and fatigue strength, and has a long service life; the non-compensation ring 4 is a 304 matrix with a layer of stellite alloy, which has the advantages of high hardness and wear resistance; the compensation ring 10 is carbon graphite, which has good wear resistance and temperature resistance, thereby helping to prolong the service life of the friction pair between the compensation ring 10 and the non-compensation ring 4; the metal structural parts such as the shaft sleeve 1, the compression ring 3, the connecting seat 6, the compensation ring seat 9 and the gland 5 are martensitic stainless steel, which has high strength and corrosion resistance; the shaft holder assembly 2 is 17-4PH stainless steel, which is a precipitation hardening type stainless steel, and the name "17-4" indicates that the material contains about 17% chromium and 4% nickel, and "PH" represents precipitation hardening. Through the selection of the material, it is proved by tests that the metal bellows mechanical seal can work for a long time under the test medium of 269℃ and 16Mpa (abs), which meets the long-period working requirement of the medium-pressure butterfly valve in the pressurized water reactor nuclear power plant. Among them, Mpa (abs) represents absolute pressure.

[0026] With reference to Figure 1 , wherein the shaft sleeve 1 includes a plurality of shaft sleeve units connected in sequence along the medium-pressure butterfly valve stem axis, and adjacent shaft sleeve units are fixedly connected by bolts; in the embodiment of the present application, the shaft sleeve unit is provided as two, the shaft holder assembly 2 is used to fasten one of the shaft sleeve units to the medium-pressure butterfly valve stem, the gland 5, the connecting seat 6, the compensation ring seat 9 and the compensation ring 10 are all aligned with the shaft sleeve unit connected with the non-compensation ring 4, and the shaft sleeve sealing ring 12 is arranged between adjacent shaft sleeve units. The shaft sleeve sealing ring 12 is located on the side of the shaft sleeve unit close to the medium-pressure butterfly valve stem, and the arrangement of the shaft sleeve sealing ring 12 helps to realize zero leakage between the shaft sleeve 1 and the valve stem.

[0027] With reference to Figure 1The gland 5 is fixedly provided with a gland sealing ring 11, and the gland sealing ring 11 is used for improving the connection sealing performance between the gland 5 and the medium-pressure butterfly valve body. The gland sealing ring 11 and the shaft sleeve sealing ring 12 are both flexible graphite sealing rings, and the flexible graphite sealing rings are helpful to adapt to the working condition of high-temperature steam in the medium-pressure butterfly valve of the pressurized water reactor nuclear power plant.

[0028] The implementation principle of the embodiment of the present application is that: in the process of rotating the valve stem of the medium-pressure butterfly valve, the shaft sleeve 1, the shaft holder assembly 2, the compression ring 3 and the non-compensation ring 4 rotate together with the valve stem, and the gland 5, the connecting seat 6, the bellows assembly 7, the auxiliary spring 8, the compensation ring seat 9 and the compensation ring 10 are fixed relative to the valve body of the medium-pressure butterfly valve, so as to realize the static mechanical sealing of the bellows assembly 7; and the friction sealing is formed between the compensation ring 10 and the non-compensation ring 4. The elastic compensation structure that the auxiliary spring 8 and the bellows assembly 7 are matched with each other is adopted, the secondary sealing is not needed, the bellows assembly 7 has excellent anti-interference ability, can not only adapt to the vibration and impact caused by the opening and closing actions of the valve, but also can provide continuous axial pressure, ensure the adhesion of the friction sealing end face, and further ensure the low leakage rate; and the material selection of the mechanical sealing parts is limited, which is helpful to meet the needs of low leakage and long-period working under the working condition of the medium-pressure butterfly valve of the pressurized water reactor nuclear power plant.

[0029] The above are the preferred embodiments of the present application, and do not limit the protection scope of the present application, so: all equivalent changes made according to the structure, shape, principle of the present application should be covered in the protection scope of the present application.

Claims

1. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant, characterized by: The application relates to a middle-pressure butterfly valve, which comprises a sleeve (1), a shaft holder assembly (2), a pressing ring (3), a non-compensation ring (4), a pressing cover (5), a connecting seat (6), a bellows assembly (7), an auxiliary spring (8), a compensation ring seat (9) and a compensation ring (10), the sleeve (1) is arranged on a valve rod of the middle-pressure butterfly valve to rotate with the valve rod, the shaft holder assembly (2) is used for connecting the sleeve (1) to the valve rod of the middle-pressure butterfly valve, the pressing ring (3) is arranged on the sleeve (1), the non-compensation ring (4) is arranged between the pressing ring (3) and the sleeve (1), the pressing cover (5) is used for being connected to a valve body of the middle-pressure butterfly valve, the connecting seat (6) is arranged on the pressing cover (5), the compensation ring seat (9) is located on one side of the connecting seat (6) close to the non-compensation ring (4), the auxiliary spring (8) and the bellows assembly (7) are arranged between the connecting seat (6) and the compensation ring seat (9), and the compensation ring (10) is arranged on one side of the compensation ring seat (9) close to the non-compensation ring (4), and the end surfaces of the compensation ring (10) and the non-compensation ring (4) are abutted to form a friction pair as a sealing surface.

2. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant according to claim 1, characterized in that: The distance from the bellows assembly (7) to the valve rod axis of the middle-pressure butterfly valve is smaller than the distance from the auxiliary spring (8) to the valve rod axis of the middle-pressure butterfly valve.

3. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant according to claim 2, characterized in that: The bellows assembly (7) is made of high-nickel-based alloy.

4. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant as defined in claim 1, wherein: The non-compensation ring (4) is made of 304 base plus surfacing stellite alloy.

5. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant as defined in claim 1, wherein: The compensation ring (10) is made of carbon graphite.

6. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant as defined in claim 1, wherein: The sleeve (1), the pressing ring (3), the connecting seat (6), the compensation ring seat (9) and the pressing cover (5) are all made of martensitic stainless steel.

7. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant as defined in claim 1, wherein: The pressing cover (5) is provided with a pressing cover sealing ring (11) for improving the sealing performance between the pressing cover (5) and the valve body of the middle-pressure butterfly valve.

8. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant according to claim 7, characterized in that: The sleeve (1) comprises a plurality of sleeve units which are sequentially connected along the valve rod axis of the middle-pressure butterfly valve, the shaft holder assembly (2) is used for fastening the sleeve units to the valve rod of the middle-pressure butterfly valve, and a sleeve sealing ring (12) is arranged between adjacent sleeve units (1).

9. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant according to claim 8, characterized in that: The pressing cover sealing ring (11) and the sleeve sealing ring (12) are both flexible graphite sealing rings.

10. A metal bellows mechanical seal for a medium pressure butterfly valve in a pressurized water reactor nuclear power plant according to any one of claims 1-9, characterized in that: The shaft holder assembly (2) is made of 17-4PH stainless steel.

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