Pneumatic pressure relief valve of nuclear primary pressure stabilizer

Abstract

The invention discloses a pneumatic pressure relief valve of a nuclear first-level pressure stabilizer, which belongs to the technical field of pressure relief valves and comprises a valve body, a valve cover is mounted above the valve body, a flow channel opening of an N-shaped structure is formed in the valve body, a valve rod is arranged in the valve body, a large valve clack is arranged at the bottom end of the valve rod, and a stop groove matched with the large valve clack is formed in the valve body. A large valve clack is arranged in the valve rod, a small valve clack is connected into the large valve clack in a sliding mode, the small valve clack is connected with the valve rod through threads, a first spring is arranged on the outer side of the small valve clack in a sleeving mode, and the two ends of the first spring make contact with the small valve clack and the large valve clack correspondingly. After the valve rod is continuously moved to open the valve, the small valve clack can drive the large valve clack to move upwards so as to finally open the valve, the operating force of the valve can be greatly reduced, and the influence of the large operating force of the valve on the anti-seismic property of the valve is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure relief valves, and in particular relates to a pneumatic pressure relief valve for a nuclear primary pressurizer. Background Art

[0002] The pneumatic pressure relief valve for a nuclear primary pressurizer is an overpressure protection device for the reactor coolant system of a pressurized water reactor nuclear power plant. It is used to prevent overpressure in the reactor coolant system during power operation and under low-temperature operating conditions. It can also be used to avoid or reduce reactor accidents and the tripping of the pressurizer safety valve, thereby providing safety protection for the pipelines and equipment in the reactor coolant system. In the prior art, when the valve is opened and closed, the valve disc is in a high-temperature and high-pressure state, and the pressure difference on both sides of the valve is large. When the medium fluid passes through the valve, it will exert a large pressure on the valve disc, reducing the service life of the valve disc. In order to solve the above problems, a pneumatic pressure relief valve for a nuclear primary pressurizer is proposed in the present application. Summary of the invention

[0003] Therefore, in order to solve the above-mentioned deficiencies, the present invention provides a pressure relief valve capable of reducing the influence of the valve operating force on the valve disc.

[0004] The present invention is implemented by constructing a nuclear primary pressurizer pneumatic pressure relief valve, including a valve body; A valve cover is installed above the valve body, and an N-shaped flow channel is provided inside the valve body. A valve stem is provided inside the valve body, and a large valve disc is provided at the bottom end of the valve stem. A stop groove matching the large valve disc is provided inside the valve body, and a small valve disc is slidably connected inside the large valve disc, and the small valve disc is connected to the valve stem through a thread. A spring 1 is sleeved on the outer side of the small valve disc, and both ends of the spring 1 are respectively in contact with the small valve disc and the large valve disc, and four groups of connecting grooves in a ring array are provided on the side of the large valve disc close to the small valve disc.

[0005] Preferably, the cross-sectional shape of the connecting groove is cylindrical, an insertion groove is provided on the side of the large valve flap close to the small valve flap, and the connecting groove is connected to the insertion groove of the small valve flap, and a chamfer is provided on the side of the large valve flap close to the small valve flap.

[0006] Preferably, a limiting protrusion is integrally provided at the top of the side of the small valve flap, and a sliding groove with a T-shaped structure is opened on the side of the large valve flap close to the limiting protrusion. The small valve flap slides inside the large valve flap through the limiting protrusion, and a valve flap pressure cover with a ring-shaped structure is installed on the side of the large valve flap close to the small valve flap.

[0007] Preferably, a plurality of groups of middle flange studs in an annular array are installed on the upper surface of the valve body, and the valve cover is installed on the upper part of the valve body through the middle flange studs, and a middle flange gasket is arranged between the valve cover and the valve body.

[0008] Preferably, a bracket is fixedly installed above the valve cover, the top end of the bracket is connected to the lower cylinder cover by a first bolt, an upper cylinder cover is installed on the upper surface of the lower cylinder cover, and the upper cylinder cover is connected to the lower cylinder cover by several groups of second bolts, a cylinder is installed on one side of the upper cylinder cover, one end of the cylinder is connected to the lower cylinder cover by a connecting pipe, a reduction gear box is fixedly installed on the top end of the upper cylinder cover, a piston rod is slidably connected to the interior of the lower cylinder cover, the top end of the valve stem passes through the interior of the valve cover and extends to the upper side of the valve cover, and the top end of the valve stem is connected to the piston rod by a coupling.

[0009] Preferably, an intermediate plate is fixedly installed inside the upper cylinder cover, a piston plate is fixedly connected to the top end of the piston rod, and the piston plate is slidably connected to the inside of the intermediate plate, a fixed rod sleeve is fixedly connected to the outer wall surface of the piston rod, a butterfly spring 1 is provided on the surface of the fixed rod sleeve, and the two ends of the butterfly spring 1 are respectively in contact with the intermediate plate and the fixed rod sleeve, a film pressure plate is fixedly connected to the bottom end of the fixed rod sleeve, a film is connected to the outer side of the film pressure plate, and the film is pressed between the lower cylinder cover and the upper cylinder cover.

[0010] Preferably, a spur gear 1 is rotatably connected to the interior of the reduction box through a bearing, the top end of the spur gear 1 passes through the interior of the reduction box and is fixedly connected to a rotating part arranged on the upper side of the reduction box, the surface of the spur gear 1 is meshingly connected to the spur gear 2, and the thickness of the spur gear 1 is greater than that of the spur gear 2, the upper side of the spur gear 2 is rotatably connected to a limiting sleeve, and the limiting sleeve slides vertically inside the reduction box, the lower side of the spur gear 2 is fixedly connected to a screw rod, the bottom end of the screw rod passes through the upper cylinder cover and extends to the interior of the upper cylinder cover, the bottom end of the screw rod is rotatably connected to a slider, and the slider slides inside the piston plate, a nut is fixedly connected to the interior of the piston plate, and the nut and the screw rod are threadedly connected.

[0011] Preferably, a sealing bushing is fixedly connected to one side of the middle plate and the upper cylinder cover close to the piston plate and the screw.

[0012] Preferably, a position indicator is installed on a side of the bracket surface close to the coupling.

[0013] Preferably, a packing body is provided on the side of the valve cover close to the valve stem, and a packing pressure plate is installed on the surface of the valve stem close to the packing body. A plurality of groups of fixing bolts are provided on the surface of the packing pressure plate, and the packing pressure plate is installed on the top of the valve cover through the fixing bolts. The outer wall surface of the fixing bolts is sequentially sleeved with a sleeve pressure plate and a protective sleeve from top to bottom, and a butterfly spring 2 is installed inside the protective sleeve. A leakage guide pipe is fixedly connected to one side of the valve cover surface.

[0014] The present invention has the following advantages: The present invention provides a nuclear primary pressurizer pneumatic pressure relief valve through improvement, which has the following improvements compared with the same type of equipment: The pneumatic pressure relief valve of the nuclear first-level regulator of the present invention is provided with a combination of large and small valve flaps. When the control valve is opened, the valve stem will first drive the small valve flap to move upward to release the blockage of the connecting groove. The flow channel openings on both sides are connected through the connecting groove, so that the inlet and outlet pressures are basically balanced, thereby achieving the effect of balancing the inlet and outlet pressures. When the valve stem is continued to be moved to open the valve, the small valve flap will drive the large valve flap to move upward to finally open the valve, which can greatly reduce the operating force of the valve and effectively reduce the influence on the valve due to the large operating force of the valve. During the opening process, the spring is always in a compressed state, which can buffer the impact of the fluid on the large valve flap, reduce the vibration of the large valve flap, and improve the overall seismic performance of the device.

[0015] The pneumatic pressure relief valve of the nuclear first-stage regulator of the present invention drives the spur gear one to rotate through the rotating part, and then the spur gear one drives the screw to rotate through the spur gear two meshingly connected therewith, and then the screw drives the piston plate to move vertically through the meshing nut, and drives the valve stem through the piston rod and the coupling, so that the position of the valve disc can be adjusted, and the effect of manually controlling the valve is achieved. The pressure value changes on the upper and lower sides of the middle plate are controlled by the cylinder, so the position of the piston plate can be adjusted, and the opening and closing of the valve can be controlled, thereby achieving the purpose of pneumatically controlling the valve to open, and manual and pneumatic do not interfere with each other, and manual operation can be performed when there is no air source. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is an overall cross-sectional view of the present invention; Figure 3 is a cross-sectional view of the valve body of the present invention; Figure 4 It is a cross-sectional view of the large valve disc in the present invention; Figure 5 is a cross-sectional view of the upper cylinder head of the present invention; Figure 6 It is a schematic diagram of the structure of the limiting sleeve and the spur gear 2 in the present invention; Figure 7 For the present invention Figure 2 The enlarged view of point A in the middle; Figure 8 It is a schematic diagram of the structure of the butterfly spring 2 and the protective sleeve in the present invention.

[0017] In the figure: 1. Valve body; 2. Valve cover; 3. Middle flange stud; 301, middle flange gasket; 4. Bracket; 5. Coupling; 6. Position indicator; 7. Lower cylinder cover; 8. Upper cylinder cover; 9. Speed ​​reducer; 10. Leakage guide pipe; 11. Cylinder; 12. Piston rod; 13. Valve stem; 14. Large valve disc; 15. Flow channel; 16. Stop groove; 17. Valve disc gland; 18. Connecting groove; 19. Spring 1; 20. Small valve disc; 21. Limiting convex block; 22. Rotating part; 23, spur gear one; 24, limiting sleeve; 25, spur gear two; 26, screw; 27, piston plate; 28, butterfly spring one; 29, intermediate plate; 30, fixed rod sleeve; 31, slider; 32, nut; 33, packing pressure plate; 34, sleeve pressure plate; 35, butterfly spring two; 36, fixing bolt; 37, packing body; 38, protective sleeve; 101, first bolt; 102, second bolt; 103, film pressure plate. DETAILED DESCRIPTION

[0018] The following will be combined with the attached Figure 1-Figure 8 The present invention is described in detail, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] See also Figure 1-Figure 8 , the pneumatic pressure relief valve of a nuclear primary pressurizer of the present invention comprises a valve body 1; A valve cover 2 is installed above the valve body 1, and a flow channel 15 in an N-shaped structure is provided inside the valve body 1. A valve stem 13 is provided inside the valve body 1, and a large valve disc 14 is provided at the bottom end of the valve stem 13. A stop groove 16 matching the large valve disc 14 is provided inside the valve body 1, and a small valve disc 20 is slidably connected inside the large valve disc 14, and the small valve disc 20 is connected to the valve stem 13 through a thread, and a spring 19 is sleeved on the outer side of the small valve disc 20, and the two ends of the spring 19 are respectively in contact with the small valve disc 20 and the large valve disc 14, and four groups of connecting grooves 18 in a ring array are provided on one side of the large valve disc 14 close to the small valve disc 20; When the valve is opened, through the setting of spring 19, the valve stem 13 will first drive the small valve flap 20 to move upward, release the blockage of the connecting groove 18, and the flow channel openings 15 on both sides are connected through the connecting groove 18, so that the inlet and outlet pressures are basically balanced, thereby achieving the effect of balancing the inlet and outlet pressures. When the valve stem 13 continues to be moved to open the valve, the small valve flap 20 will drive the large valve flap 14 to move upward to finally open the valve, which can greatly reduce the operating force of the valve and effectively reduce the impact on the valve due to the large operating force of the valve. During the opening process, the spring 19 is always in a compressed state, which can buffer the impact of the fluid on the large valve flap 14, reduce the vibration of the large valve flap 14, and improve the overall anti-seismic performance of the device.

[0020] The cross-sectional shape of the connecting groove 18 is cylindrical, an insertion groove is provided on the side of the large valve flap 14 close to the small valve flap 20, and the connecting groove 18 is connected to the insertion groove of the small valve flap 20, and a chamfer is provided on the side of the large valve flap 14 close to the small valve flap 20; a limiting protrusion 21 is integrally provided on the top of the side of the small valve flap 20, and a sliding groove with a T-shaped structure is provided on the side of the large valve flap 14 close to the limiting protrusion 21, and the small valve flap 20 slides inside the large valve flap 14 through the limiting protrusion 21, and a valve flap gland 17 with an annular structure is installed on the side of the large valve flap 14 close to the small valve flap 20; a plurality of groups of middle flange studs 3 in an annular array are installed on the upper surface of the valve body 1, and the valve cover 2 is installed above the valve body 1 through the middle flange studs 3, and a middle flange gasket 301 is provided between the valve cover 2 and the valve body 1; The internal chamfer of the large valve flap 14 matches the small valve flap 20, so as to improve the sealing effect of the small valve flap 20 when it is closed. When the valve stem 13 is moved to drive the small valve flap 20 to move, the valve stem 13 will drive the limiting protrusion 21 to slide inside the large valve flap 14, and the movement of the small valve flap 20 is guided by the limiting protrusion 21. The sliding groove where the limiting protrusion 21 is located is in a T-shaped structure, so as to limit the movement of the limiting protrusion 21, and thus to ensure the connection between the small valve flap 20 and the large valve flap 14, so that the small valve flap 20 can drive the large valve flap 14 to open. The arrangement of the valve flap gland 17 can prevent the small valve flap 20 from loosening and falling off from the inside of the large valve flap 14. The small valve flap 20 and the valve stem 13 are threadedly connected, and the valve flap gland 17 is detachably installed inside the large valve flap 14 by screws, so that the small valve flap 20 can be replaced after the valve flap gland 17 is removed.

[0021] A bracket 4 is fixedly installed above the valve cover 2, and the top of the bracket 4 is connected to the lower cylinder cover 7 through a first bolt 101. An upper cylinder cover 8 is installed on the upper surface of the lower cylinder cover 7, and the upper cylinder cover 8 is connected to the lower cylinder cover 7 through a plurality of groups of second bolts 102. A cylinder 11 is installed on one side of the upper cylinder cover 8, and the input end and output end of the cylinder 11 are respectively connected to the upper cylinder cover 8 and the lower cylinder cover 7 through a connecting pipe. A reduction box 9 is fixedly installed on the top of the upper cylinder cover 8, and a piston rod 12 is slidably connected to the interior of the lower cylinder cover 7. The top of the valve stem 13 passes through the interior of the valve cover 2 and extends to the upper side of the valve cover 2, and the top of the valve stem 13 passes through the top of the valve cover 2. It is connected to the piston rod 12 through the coupling 5; an intermediate plate 29 is fixedly installed inside the upper cylinder cover 8, a piston plate 27 is fixedly connected to the top of the piston rod 12, and the piston plate 27 is slidably connected to the inside of the intermediate plate 29, and a fixed rod sleeve 30 is fixedly connected to the outer wall of the piston rod 12, and a butterfly spring 28 is sleeved on the surface of the fixed rod sleeve 30, and the two ends of the butterfly spring 28 are respectively in conflict with the intermediate plate 29 and the fixed rod sleeve 30, and the bottom end of the fixed rod sleeve 30 is fixedly connected to a film pressure plate 103, and a film is connected to the outer side of the film pressure plate 103, and this film is pressed between the lower cylinder cover 7 and the upper cylinder cover 8; The two sides of the piston plate 27 are integrally fixed with strip-shaped protrusions, which can limit the movement of the piston plate 27, so that the piston plate 27 slides vertically on the surface of the middle plate 29. The lower cylinder cover 7 and the film form an air chamber cavity. By starting the cylinder 11, air is delivered to the inside of the air chamber cavity, and the pressure inside the cavity increases, which will push the film pressure plate 103 to move upward, and then the film pressure plate 103 pushes the piston plate 27 to move, and drives the valve stem 13 to move upward through the piston rod 12 and the coupling 5, and then the valve stem 13 can be driven to move through the cylinder 11 to control the opening and closing of the valve, thereby achieving the effect of pneumatically controlling the opening and closing of the pressure relief valve; A spur gear 23 is rotatably connected to the interior of the reduction box 9 through a bearing. The top of the spur gear 23 passes through the interior of the reduction box 9 and is fixedly connected to a rotating member 22 arranged on the upper side of the reduction box 9. The surface of the spur gear 23 is meshingly connected to a spur gear 25, and the thickness of the spur gear 23 is greater than that of the spur gear 25. The upper side of the spur gear 25 is rotatably connected to a limiting sleeve 24, and the limiting sleeve 24 slides vertically in the reduction box 9. A screw rod 26 is fixedly connected to the lower side of the spur gear 25, and the bottom end of the screw rod 26 passes through the upper cylinder cover 8 and extends to the interior of the upper cylinder cover 8. A slider 31 is rotatably connected to the bottom end of the screw rod 26, and the slider 31 slides in the interior of the piston plate 27. A nut 32 is fixedly connected to the interior of the piston plate 27, and the nut 32 and the screw rod 26 are threadedly connected; a sealing bushing is fixedly connected to the middle plate 29 and the side of the upper cylinder cover 8 close to the piston plate 27 and the screw rod 26.

[0022] The spur gear 1 23 is driven to rotate by the rotating member 22, and then the spur gear 1 23 drives the screw 26 to rotate through the spur gear 25 meshing with it, and then the screw 26 drives the piston plate 27 to move vertically through the meshing nut 32, and drives the valve disc to move vertically through the piston rod 12 and the valve stem 13, so as to control the opening and closing of the valve body 1, and realize manual control of the opening and closing of the valve body 1. The setting of the spur gear 1 23 and the spur gear 2 25 reduces the manual operation torque, making the manual operation more convenient. The sealing bushing inside the middle plate 29 and the upper cylinder cover 8 can improve the sealing effect of the upper cylinder cover 8 and the lower cylinder cover 7, and improve the accuracy of pneumatic control.

[0023] When the pressure relief valve is switched by pneumatic control, the piston plate 27 can drive the spur gear 2 25 to move vertically through the nut 32 and the screw rod 26. The spur gear 2 25 will slide on the side of the spur gear 1 23 without affecting the meshing of the spur gear 1 23 and the spur gear 2 25. Manual and pneumatic operations do not interfere with each other. Manual operation can be performed when there is no air source, thereby improving the flexibility of the device.

[0024] A position indicator 6 is installed on the side of the bracket 4 surface close to the coupling 5; a packing body 37 is provided on the side of the valve cover 2 close to the valve stem 13, a packing pressure plate 33 is installed on the side of the valve stem 13 close to the packing body 37, a plurality of sets of fixing bolts 36 are arranged on the surface of the packing pressure plate 33, and the packing pressure plate 33 is installed on the upper part of the valve cover 2 through the fixing bolts 36, and the outer wall surface of the fixing bolt 36 is sleeved with a sleeve pressure plate 34 and a protective sleeve 38 in sequence from top to bottom, a butterfly spring 2 35 is installed inside the protective sleeve 38, and a leakage guide pipe 10 is fixedly connected to one side of the surface of the valve cover 2; The position of the coupling 5 can be monitored by the position indicator 6, and then the opening and closing size of the large valve flap 14 and the small valve flap 20 can be equivalently monitored. The piston plate 27 adopts a combination of braiding + flexible graphite and adopts a disc spring floating preload. The disc spring has a compact structure compared to the coil spring and is not easy to become unstable.

[0025] It should be noted that: the valve body 1 adopts an integral free forging structure, and the seal between the valve body 1 and the valve disc adopts a cone-surface-welded cobalt-based hard alloy seal; the connection between the valve body 1 and the valve cover 2 adopts a structure combining a middle flange stud 3 connection and lip fusion welding, which can better ensure the sealing performance; the middle flange stud 3 connection is more conducive to maintenance and disassembly and assembly compared with the self-tightening seal structure; a sealing welding structure is provided at the connection between the valve body 1 and the valve cover 2 as a backup seal for the sealing gasket, and the sealing welding length allows three cutting and re-welding.

[0026] The present invention provides a pneumatic pressure relief valve for a nuclear primary pressurizer through improvement, and its working principle is as follows: First, when the pneumatic control valve needs to be opened, the air on the upper side of the middle plate 29 is first transported to the inside of the air chamber by starting the cylinder 11. The pressure inside the chamber increases, pushing the film pressure plate 103 upward, so that the piston plate 27 will move upward under pressure, and then the piston plate 27 drives the valve stem 13 to move upward through the piston rod 12 and the coupling 5, and then the valve stem 13 can be driven to move through the cylinder 11. Under the action of the spring 19, the valve stem 13 will first drive the small valve flap 20 to move upward, release the blockage of the connecting groove 18, so that the inlet and outlet pressures are basically balanced, and then continue to adjust the pressure on the upper and lower sides of the middle plate 29. The small valve flap 20 will drive the large valve flap 14 to move upward, so as to finally open the valve and realize the opening of the pneumatic control valve.

[0027] Second, when it is necessary to manually control the valve to open, the rotating member 22 drives the spur gear 1 23 to rotate, and then the spur gear 1 23 drives the screw 26 to rotate through the spur gear 2 25 meshing with it, and then the screw 26 drives the piston plate 27 to move vertically through the meshing nut 32, and drives the valve stem 13 to move upward through the piston rod 12 and the coupling 5, and then can drive the valve stem 13 to move through the cylinder 11, and drive the small valve flap 20 and the large valve flap 14 to move through the valve stem 13, so as to achieve the purpose of manually controlling the valve to open.

[0028] Third, when the cylinder 11 stops working, the upper and lower sides of the middle plate 29 are connected through the cylinder 11, so that after the pressure relief valve is manually controlled to be switched, there will be no pressure difference between the upper and lower sides of the middle plate 29, thereby preventing the piston plate 27 from resetting. When the pressure relief valve is pneumatically controlled to be switched, the piston plate 27 can drive the spur gear 2 25 to move vertically through the nut 32 and the screw 26, and the spur gear 2 25 will slide on the side of the spur gear 1 23, which will not affect the meshing of the spur gear 1 23 and the spur gear 2 25, so that manual and pneumatic operations do not interfere with each other, and manual operation can be performed when there is no air source.

[0029] Fourth, when the valve is opened, under the action of spring 19, the valve stem 13 will first drive the small valve flap 20 to move upward, release the blockage of the connecting groove 18, and the flow channel openings 15 on both sides are connected through the connecting groove 18, so that the inlet and outlet pressures are basically balanced, thereby achieving the effect of balancing the inlet and outlet pressures. When the valve stem 13 continues to be moved to open the valve, the small valve flap 20 will drive the large valve flap 14 to move upward, so as to finally open the valve, which can greatly reduce the operating force of the valve and effectively reduce the impact on the valve due to the large operating force of the valve. During the opening process, the spring 19 is always in a compressed state, which can buffer the impact of the fluid on the large valve flap 14 and reduce the vibration of the large valve flap 14.

[0030] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pneumatic pressure relief valve for a nuclear primary pressurizer, comprising a valve body (1); Features: A valve cover (2) is installed above the valve body (1); a flow passage (15) in an N-shaped structure is provided inside the valve body (1); a valve stem (13) is provided inside the valve body (1); a large valve flap (14) is provided at the bottom end of the valve stem (13); a stop groove (16) matching the large valve flap (14) is provided inside the valve body (1); a small valve flap (20) is slidably connected inside the large valve flap (14); the small valve flap (20) is connected to the valve stem (13) by a thread; a spring (19) is sleeved on the outer side of the small valve flap (20); two ends of the spring (19) are respectively in contact with the small valve flap (20) and the large valve flap (14); and four groups of connecting grooves (18) in a ring array are provided on a side of the large valve flap (14) close to the small valve flap (20).

2. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 1, characterized in that: The cross-sectional shape of the connecting groove (18) is cylindrical, an insertion groove is provided on a side of the large valve flap (14) close to the small valve flap (20), and the connecting groove (18) is connected to the insertion groove of the small valve flap (20), and a chamfer is provided on a side of the large valve flap (14) close to the small valve flap (20).

3. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 2 is characterized in that: A limiting protrusion (21) is integrally provided at the top end of the side of the small valve flap (20); a sliding groove with a T-shaped structure is provided inside the large valve flap (14) on a side close to the limiting protrusion (21); the small valve flap (20) slides inside the large valve flap (14) via the limiting protrusion (21); and a valve flap gland (17) with an annular structure is installed on a side of the large valve flap (14) close to the small valve flap (20).

4. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 3 is characterized in that: A plurality of groups of middle flange studs (3) in a ring-shaped array are mounted on the upper surface of the valve body (1), and the valve cover (2) is mounted on the upper side of the valve body (1) via the middle flange studs (3), and a middle flange gasket (301) is arranged between the valve cover (2) and the valve body (1).

5. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 1, characterized in that: A bracket (4) is fixedly mounted above the valve cover (2), the top end of the bracket (4) is connected to the lower cylinder cover (7) via a first bolt (101), an upper cylinder cover (8) is mounted on the upper surface of the lower cylinder cover (7), and the upper cylinder cover (8) is connected to the lower cylinder cover (7) via a plurality of groups of second bolts (102) (not shown), a cylinder (11) is mounted on one side of the upper cylinder cover (8), one end of the cylinder (11) is connected to the lower cylinder cover (7) via a connecting pipe, a reduction box (9) is fixedly mounted on the top end of the upper cylinder cover (8), a piston rod (12) is slidably connected to the interior of the lower cylinder cover (7), the top end of the valve stem (13) passes through the interior of the valve cover (2) and extends to the upper side of the valve cover (2), and the top end of the valve stem (13) is connected to the piston rod (12) via a coupling (5).

6. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 5, characterized in that: An intermediate plate (29) is fixedly installed inside the upper cylinder cover (8), the top end of the piston rod (12) is fixedly connected to a piston plate (27), and the piston plate (27) is slidably connected to the inside of the intermediate plate (29), the outer wall surface of the piston rod (12) is fixedly connected to a fixed rod sleeve (30), the surface of the fixed rod sleeve (30) is sleeved with a butterfly spring (28), and the two ends of the butterfly spring (28) are respectively in contact with the intermediate plate (29) and the fixed rod sleeve (30), the bottom end of the fixed rod sleeve (30) is fixedly connected to a film pressure plate (103), the outer side of the film pressure plate (103) is connected to a film, and the film is pressed between the lower cylinder cover (7) and the upper cylinder cover (8).

7. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 6, characterized in that: A spur gear 1 (23) is rotatably connected to the interior of the reduction box (9) via a bearing, the top end of the spur gear 1 (23) passes through the interior of the reduction box (9) and is fixedly connected to a rotating member (22) arranged on the upper side of the reduction box (9), a spur gear 2 (25) is meshedly connected to the surface of the spur gear 1 (23), and the thickness of the spur gear 1 (23) is greater than that of the spur gear 2 (25), the upper side of the spur gear 2 (25) is rotatably connected to a limiting sleeve (24), and the limiting sleeve (24) is ) slides vertically inside the reduction box (9), a screw rod (26) is fixedly connected to the lower side of the spur gear 2 (25), the bottom end of the screw rod (26) passes through the upper cylinder cover (8) and extends to the inside of the upper cylinder cover (8), the bottom end of the screw rod (26) is rotatably connected to a slider (31), and the slider (31) slides inside the piston plate (27), a nut (32) is fixedly connected to the inside of the piston plate (27), and the nut (32) and the screw rod (26) are threadedly connected.

8. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 7, characterized in that: A sealing bushing is fixedly connected to the middle plate (29) and the inner side of the upper cylinder cover (8) close to the piston plate (27) and the screw rod (26).

9. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 5, characterized in that: A position indicator (6) is installed on a side of the surface of the bracket (4) close to the coupling (5).

10. The pneumatic pressure relief valve for a nuclear primary pressurizer according to claim 9, characterized in that: A packing body (37) is provided on the side of the valve cover (2) close to the valve stem (13), and a packing pressure plate (33) is installed on the side of the surface of the valve stem (13) close to the packing body (37). A plurality of sets of fixing bolts (36) are provided on the surface of the packing pressure plate (33), and the packing pressure plate (33) is installed above the valve cover (2) via the fixing bolts (36). A sleeve pressure plate (34) and a protective sleeve (38) are sequentially sleeved on the outer wall surface of the fixing bolt (36) from top to bottom, and a butterfly spring 2 (35) is installed inside the protective sleeve (38). A leakage guide pipe (10) is fixedly connected to one side of the surface of the valve cover (2).

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