Valve air leakage prevention structure for nuclear power unit

Abstract

The invention relates to an air leakage prevention structure, in particular to a valve air leakage prevention structure for a nuclear power unit. The problem that in the prior art, after a nuclear power unit operates for a long time, a valve shaft of a valve leaks air at the driving end is solved. A valve shaft extension rod is installed at the driving end of a valve shaft, and the valve shaft extension rod sequentially penetrates through a support, a gland, a ball bearing and a thrust bearing. The gland is inserted into the support, a plurality of supporting legs are installed on the support, and the end faces of the supporting legs abut against a driving mechanism of the valve. After the spring is compressed, on one hand, the force of the spring abuts against the support to enable the supporting leg to abut against a driving mechanism of the valve, on the other hand, the force of the spring abuts against the gland to enable the gland to abut against the locking nut, and then the locking nut transmits the force of the spring to the valve shaft extension rod, so that the valve shaft is axially tensioned, and a gap at the sealing position of the driving end is reduced; steam at the non-driving end is prevented from flowing to the driving end, and then air leakage at the driving end is prevented. The invention belongs to the technical field of nuclear power high-pressure valves and valve air leakage prevention.

Description

Technical Field

[0001] The invention relates to an anti-leakage structure, in particular to an anti-leakage structure of a valve for a nuclear power unit, belonging to the technical field of high-pressure valves and anti-leakage valves for nuclear power. Background Art

[0002] At present, after ten years of operation, nuclear power units have leakage in the valve shaft of their high-pressure main steam valves at the driving end. The leaked gas forms condensed water after cooling, which seriously affects the economy and safety of the unit.

[0003] After disassembling the valve for inspection, it was found that the leakage was caused by the enlarged gap of the bowl-shaped sealing ring at the driving end of the valve shaft. This was caused by the valve structure itself: the valve driving mechanism was arranged at one end of the valve housing, and the valve shaft passed through the valve housing and the driving mechanism. When the unit was started / shutdown, a slight vacuum was drawn at the non-driving end of the valve shaft, and the valve shaft moved toward the non-driving end under the action of the atmosphere, causing the sealing structure at the driving end to loosen and the valve to open or close. When the unit was running, steam entered the chamber at the non-driving end, and the sealing gasket at the driving end was compressed by the steam pressure difference to achieve a sealing effect. Figure 1 As shown in the figure, as the gap at the driving end seal becomes larger, the steam at the non-driving end continuously flows to the driving end, which leads to air leakage at the driving end.

[0004] In summary, how to propose a valve anti-leakage structure to address the above technical issues has become an urgent problem to be solved by technicians in this field. Summary of the invention

[0005] The present invention aims at the above-mentioned deficiencies of the prior art and provides a valve anti-leakage structure for a nuclear power unit.

[0006] The technical solution of the present invention is: a valve anti-leakage structure for a nuclear power unit, comprising a valve shaft extension rod, a support, a spring, a gland, a ball bearing and a thrust bearing.

[0007] The gland is coaxially inserted on the support by means of clearance fit.

[0008] The spring is installed in the support, and the two end surfaces of the spring are respectively against the support and the pressure cover.

[0009] Two locking nuts are installed on the valve shaft extension rod, one end of the valve shaft extension rod is fixedly connected to the driving end of the valve shaft, and the other end of the valve shaft extension rod passes through the support, the pressure cover, the ball bearing and the thrust bearing in sequence.

[0010] The outer ring of the ball bearing is embedded in the gland, and the inner ring of the ball bearing is mounted on the valve shaft extension rod in a clearance fit manner; the two end surfaces of the thrust bearing are respectively against the gland and the locking nut.

[0011] A plurality of legs are mounted on the support in a circular array, and the end faces of the legs are against the driving mechanism of the valve.

[0012] Compared with the prior art, the present invention has the following effects:

[0013] 1. The present invention has a simple structure and a compact size. The butterfly spring provides spring force to axially tighten the valve shaft 100, reduce the gap at the seal of the driving end, and thus achieve the sealing of the valve. The displacement of the valve shaft can be adjusted by controlling the spring force. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a valve leaking in the prior art;

[0015] Figure 2 It is a schematic diagram of the structure of the present invention;

[0016] Figure 3 It is a schematic diagram of the present invention being installed on a valve for use.

[0017] In the figure: 1, valve shaft extension rod; 1-1, locking nut; 2, support leg; 3, support; 4, spring; 5, pressure cover; 5-1, ball bearing; 5-2, thrust bearing; 100, valve shaft. DETAILED DESCRIPTION

[0018] In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0019] Specific implementation method 1: Combination Figures 2 to 3 The present embodiment is described as a valve anti-leakage structure for a nuclear power unit, comprising a valve shaft extension rod 1, a support 3, a spring 4, a gland 5, a ball bearing 5-1 and a thrust bearing 5-2.

[0020] The pressure cover 5 is coaxially inserted on the support 3 by means of clearance fit.

[0021] The spring 4 is installed in the support 3, and both end surfaces of the spring 4 abut against the support 3 and the pressure cover 5 respectively.

[0022] Two locking nuts 1-1 are installed on the valve shaft extension rod 1. One end of the valve shaft extension rod 1 is fixedly connected to the driving end of the valve shaft 100, and the other end of the valve shaft extension rod 1 passes through the support 3, the pressure cover 5, the ball bearing 5-1 and the thrust bearing 5-2 in sequence.

[0023] The outer ring of the ball bearing 5-1 is embedded in the pressure cover 5, and the inner ring of the ball bearing 5-1 is mounted on the valve shaft extension rod 1 by means of clearance fit; the two end faces of the thrust bearing 5-2 are respectively against the pressure cover 5 and the locking nut 1-1. In this way, the combination of the ball bearing 5-1 and the thrust bearing 5-2 is used to prevent the valve shaft extension rod 1 from getting stuck when rotating.

[0024] A plurality of legs 2 are mounted on the support 3 in a circular array, and the end faces of the legs 2 abut against the driving mechanism of the valve.

[0025] Specific implementation method 2: Combination Figure 2 This embodiment further includes a washer 6, which is sleeved on the valve shaft extension rod 1 and arranged between the locking nut 1-1 and the thrust bearing 5-2. Other components and connection relationships are the same as those of the first embodiment.

[0026] Specific implementation method three: Combination Figure 2 To explain this embodiment, in this embodiment, the leg 2 is installed on the support 3 by means of threaded connection.

[0027] Furthermore, the number of the legs 2 is 3. This arrangement has the following advantages:

[0028] 1. The support 3 is isolated from the valve by the support legs 2, which effectively reduces heat conduction, so that the present invention can be installed and maintained while the unit is running, avoiding the installation and maintenance having to be processed only after the unit is shut down.

[0029] 2. Sufficient maintenance space is reserved between the support 3 and the valve through the support leg 2, so that the valve shaft extension rod 1 can be inspected at any time regardless of whether the unit is running.

[0030] 3. Reduce the contact area between the support leg 2 and the valve, thereby reducing the friction between the two. When an emergency occurs (such as the ball bearing 5-1 or the thrust bearing 5-2 is stuck and cannot rotate smoothly), the support leg 2 and the valve will not affect the normal rotation of the valve shaft 100, thereby ensuring that the valve can be opened or closed normally.

[0031] The valve shaft extension rod 1 is connected to the driving end of the valve shaft 100 via threads.

[0032] The other components and connection relationships are the same as those in the first or second specific implementation.

[0033] Specific implementation method four: Combination Figure 2 In this embodiment, the spring 4 is a butterfly spring. This arrangement has the following advantages:

[0034] 1. A butterfly spring is used to provide spring force to axially tighten the valve shaft 100, reduce the gap at the seal of the driving end, and thus achieve the sealing of the valve. The displacement of the valve shaft can be adjusted by controlling the spring force. When the spring force needs to be adjusted, the unit operates normally without stopping. The locking nut 1-1 can be screwed to control the compression length of the butterfly spring. Two locking nuts 1-1 can prevent loosening.

[0035] 2. When the steam pressure difference exceeds the bearing capacity, the butterfly spring can undergo irreversible deformation, thereby reducing the spring force, thereby preventing the present invention from damaging the valve body.

[0036] The other components and connection relationships are the same as those of the first, second or third specific implementation modes.

[0037] How it works

[0038] The valve shaft extension rod 1 is installed on the driving end of the valve shaft 100, and the valve shaft extension rod 1 passes through the support 3, the pressure cover 5, the ball bearing 5-1 and the thrust bearing 5-2 in sequence.

[0039] The gland 5 is inserted on the support 3, and a plurality of legs 2 are installed on the support 3, and the end faces of the legs 2 are against the driving mechanism of the valve.

[0040] The two end surfaces of the spring 4 are respectively against the support 3 and the pressure cover 5; the pressure cover 5 is rotatably connected to the valve shaft extension rod 1 through the ball bearing 5-1, and the ball bearing 5-1 can move along the axial direction of the valve shaft extension rod 1; the two end surfaces of the thrust bearing 5-2 are respectively against the locking nut 1-1 installed on the pressure cover 5 and the valve shaft extension rod 1.

[0041] After the spring 4 is compressed, the spring force, on the one hand, presses the support 3 tightly, so that the support leg 2 is against the driving mechanism of the valve, and on the other hand, presses the pressure cover 5 tightly, so that the pressure cover 5 is against the locking nut 1-1. Then the locking nut 1-1 transmits the spring force to the valve shaft extension rod 1 to axially tighten the valve shaft 100, reduce the gap at the seal of the driving end, and then realize the sealing of the valve, prevent the steam at the non-driving end from flowing to the driving end, and then prevent air leakage at the driving end.

[0042] The present invention has been disclosed as above in the form of a preferred embodiment, but it is not intended to limit the present invention. Any simple modification, equivalent changes and modifications made to the above implementation cases by any professional and technical personnel who do not deviate from the content of the technical solution of the present invention and based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A valve anti-leakage structure for a nuclear power unit, characterized in that: It comprises a valve shaft extension rod (1), a support (3), a spring (4), a gland (5), a ball bearing (5-1) and a thrust bearing (5-2); The gland (5) is coaxially inserted on the support (3) by means of clearance fit; The spring (4) is installed in the support (3), and the two end surfaces of the spring (4) are respectively against the support (3) and the pressure cover (5); Two locking nuts (1-1) are installed on the valve shaft extension rod (1); one end of the valve shaft extension rod (1) is fixedly connected to the driving end of the valve shaft (100); the other end of the valve shaft extension rod (1) passes through the support (3), the gland (5), the ball bearing (5-1) and the thrust bearing (5-2) in sequence; The outer ring of the ball bearing (5-1) is embedded in the gland (5), and the inner ring of the ball bearing (5-1) is sleeved on the valve shaft extension rod (1) by means of clearance fit; the two end surfaces of the thrust bearing (5-2) are respectively against the gland (5) and the locking nut (1-1); A plurality of legs (2) are mounted on the support (3) in a circular array, and the end faces of the legs (2) abut against the driving mechanism of the valve.

2. The valve anti-leakage structure for a nuclear power unit according to claim 1, characterized in that: It also comprises a washer (6), which is sleeved on the valve shaft extension rod (1), and the washer (6) is arranged between the locking nut (1-1) and the thrust bearing (5-2).

3. The valve anti-leakage structure for a nuclear power unit according to claim 2, characterized in that: The number of the supporting legs (2) is 3.

4. The valve anti-leakage structure for a nuclear power unit according to claim 3, characterized in that: The supporting leg (2) is mounted on the supporting base (3) by means of a threaded connection.

5. The valve anti-leakage structure for a nuclear power unit according to claim 4, characterized in that: The valve shaft extension rod (1) is connected to the driving end of the valve shaft (100) via threads.

6. The valve anti-leakage structure for a nuclear power unit according to claim 5, characterized in that: The spring (4) is a butterfly spring.

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