A piston drive mechanism for a pressure relief vent valve

Abstract

The application provides a piston driving mechanism for a pressure relief valve, comprising a valve cover, a piston, a valve rod, a reset spring and a bellows; the valve cover comprises a cover plate, a first accommodating section and a second accommodating section connected in sequence; the cover plate is installed at an inlet end of a valve body; a first accommodating cavity for accommodating the piston is formed in the first accommodating section; a second accommodating cavity for accommodating the valve rod and the reset spring is formed in the second accommodating section, and the reset spring is assembled on the valve rod; the piston is in sealing connection with the first accommodating cavity; a front end of the valve rod is connected with the piston, and a rear end of the valve rod penetrates out of the second accommodating cavity. The piston driving mechanism of the application is automatically and reliably started under the action of differential pressure, drives a valve knife structure to cut a burst diaphragm, discharges high-temperature and high-pressure gas in a safety shell to a pre-set area, realizes reliable pressure relief of the safety shell, ensures the integrity of a radioactive containment barrier, and the safety shell pressure relief valve has high reliability.

Description

Technical Field

[0001] This invention relates to valve equipment, and more specifically to a piston drive mechanism for a pressure relief valve. Background Technology

[0002] Containment depressurization devices are classified as safety level 2 equipment, requiring extremely high reliability and precision. Existing pressure relief safety devices are insufficient to meet increasingly stringent nuclear safety requirements. Currently, commonly used containment or auxiliary building depressurization devices primarily employ pressure relief safety devices composed of rupture discs and clamps. When the pressure difference across the rupture disc reaches a predetermined value at a predetermined temperature, the rupture disc ruptures or detaches, releasing the pressurized medium. However, due to factors such as the rupture disc material, manufacturing process, and installation schedule, the calibrated burst pressure of the rupture disc often deviates significantly from the design value. Furthermore, rupture disc testing can only be conducted through sampling tests on materials from the same batch, meaning the test results only represent the burst pressure of the selected rupture disc and cannot prove the accurate burst pressure values ​​of other rupture discs. In other words, existing pressure relief safety devices lack a dedicated drive mechanism to drive the cutting element to cut the rupture disc. In practical use, there is a risk that the rupture disc may not rupture under the design pressure, making it difficult to meet increasingly stringent nuclear safety requirements and resulting in low reliability. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a piston drive mechanism for a pressure relief valve, which aims to solve the problem that the rupture disc in existing pressure relief safety devices cannot rupture under the design pressure.

[0004] The technical solution adopted in this invention is as follows: a piston drive mechanism for a pressure relief valve, comprising a valve cover, a piston, a valve stem, a return spring, and a bellows; the valve cover includes a cover plate, a first receiving section, and a second receiving section connected in sequence; the cover plate is installed at the inlet end of the pressure relief valve body; a first receiving cavity for accommodating the piston is provided in the first receiving section, and a second receiving cavity for accommodating the valve stem and the return spring is provided in the second receiving section, the return spring being assembled on the valve stem; the first receiving cavity and the second receiving cavity are coaxial and connected; the piston is sealed to the first receiving cavity; the front end of the valve stem is connected to the piston, and the rear end of the valve stem extends out from the second receiving cavity; the bellows is coaxially sleeved outside the second receiving section of the valve cover, the front end of the bellows is connected to the first receiving section of the valve cover through a first support ring, and the rear end of the bellows is connected to the center seat through a second support ring.

[0005] According to the above scheme, the first receiving section is connected to the middle of the cover plate, and the edge of the cover plate is provided with multiple waist-shaped holes.

[0006] According to the above scheme, a one-way exhaust valve is provided at the end of the bellows.

[0007] According to the above scheme, the inlet end of the first receiving cavity is connected to an orifice plate, and the orifice plate has flow holes.

[0008] According to the above scheme, the total area of ​​the waist-shaped holes is greater than the flow cross-sectional area of ​​the pressure relief valve.

[0009] According to the above scheme, the return spring is connected to the valve stem through a spring seat.

[0010] According to the above scheme, the piston is also provided with an internal pressure discharge mechanism; the internal pressure discharge mechanism includes a threaded sleeve, a valve disc and a spring. The piston has a discharge hole, the threaded sleeve is installed inside the discharge hole, the spring is installed outside the threaded sleeve, the valve disc is located at the outer port of the discharge hole, and the valve disc is connected to one end of the spring.

[0011] According to the above scheme, the first receiving cavity of the valve cover and the piston are sealed with an O-ring.

[0012] According to the above scheme, the corrugated pipe is made of metal material.

[0013] According to the above scheme, the bellows is sealed to the first support ring and the second support ring by a sealing weld; the first support ring is sealed to the first receiving section of the valve cover by an O-ring; and the first support ring is bolted to the first receiving section of the valve cover.

[0014] The beneficial effects of this invention are as follows:

[0015] (1) The piston drive mechanism of the present invention automatically and reliably starts under differential pressure, drives the valve knife structure to cut the burst diaphragm, and discharges the high temperature and high pressure gas in the containment to a pre-set area, thereby realizing reliable depressurization of the containment and ensuring the integrity of the radioactive containment barrier. The containment depressurization discharge valve has high reliability. The valve knife structure is driven by the pressure difference between the containment and the piston cavity, and does not require external energy supply or personnel intervention to drive the valve assembly.

[0016] (2) The piston drive mechanism of the present invention can adjust the valve action pressure to be set by adjusting the spring preload, so as to reliably and automatically start cutting the rupture metal diaphragm when the internal pressure of the containment reaches the set pressure value after an accident, thereby realizing the depressurization of the containment; at the same time, the spring plays a reset role. When the rupture diaphragm is cut off, the internal pressure of the containment has been discharged, and the pressure inside and outside the bellows is nearly balanced. Under the action of the spring force, the valve knife structure returns to its original position; the start pressure is set by adjusting the spring preload; and the drive mechanism meets the anti-vibration and shock performance through the spring seat.

[0017] (3) The present invention provides an internal pressure discharge mechanism on the piston. When the pressure rises to a certain value, the valve opens and the excess gas caused by compression is discharged, maintaining the pressure difference required to drive the valve knife structure without affecting the valve knife running speed.

[0018] (4) The present invention has multiple evenly distributed waist-shaped holes around the valve cover. The total area of ​​the waist-shaped holes is greater than the flow cross-sectional area, ensuring that the valve flow capacity meets the design requirements. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the pressure relief valve in this invention. Figure 1 .

[0020] Figure 2 Schematic diagram of pressure relief valve Figure 2 .

[0021] Figure 3 for Figure 1 The left view.

[0022] Figure 4 This is a schematic diagram of a piston drive mechanism.

[0023] Figure 5 This is a schematic diagram of the valve cover.

[0024] Figure 6 This is a schematic diagram of a bellows structure.

[0025] Figure 7 This is a schematic diagram of the valve knife structure.

[0026] Wherein: 1-Orifice plate; 1.1-Flow hole; 2-Valve cover; 2.1-Oval orifice; 2.2-First receiving section; 2.3-Second receiving section; 3-Piston; 4-Spring; 5-Valve body; 5.1-Guide boss; 6-First support ring; 7-Bellows; 8-Valve knife structure; 8.1-Center seat; 8.2-Connecting rib; 8.3-Cylinder; 8.4-Knife edge; 8.5-Groove; 8.6-Large diameter section; 8.7-Conical section; 8.8-Small diameter section; 9-Second support ring; 10-Valve stem; 11-Breaking diaphragm; 12-Valve seat; 13-Internal pressure discharge mechanism; 14-Spring seat. Detailed Implementation

[0027] To better understand the present invention, it will be further described below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1 , 2As shown in Figure 3, a pressure relief valve is specifically a containment pressure relief valve, which includes a valve body 5, a rupture diaphragm 11, a piston drive mechanism, a valve knife structure 8, and a valve seat 12. The valve body 5 is hollow inside. The piston drive mechanism, valve knife structure 8, and rupture diaphragm 11 are coaxially installed inside the valve body 5 in sequence, and the valve seat 12 is installed at the outlet end of the valve body 5. The drive end of the piston drive mechanism is connected to the valve knife structure 8, and the rupture diaphragm 11 is located at the outlet of the valve body 5 to seal the outlet passage of the valve body 5. When the pressure inside the containment reaches a set value, the drive end of the piston drive mechanism drives the valve knife structure 8 to move axially, and the valve knife structure 8 punctures the rupture diaphragm 11, thereby opening the pressure relief valve and allowing the medium to pass through, thus achieving the purpose of depressurizing the containment.

[0029] In this invention, a rupture diaphragm 11 is provided at the outlet of the valve body 5 to effectively isolate the containment vessel from the outside under normal conditions, ensuring the containment vessel's airtightness. The rupture diaphragm 11 is made of metal.

[0030] Preferably, the outlet end of the valve body 5 adopts a standard butt weld joint, and the sealing part with the burst diaphragm 11 adopts a welding process. The sealing surfaces of the two are ground, and a water line is engraved on the sealing surface to form a labyrinth seal with the burst diaphragm 11, thereby improving the sealing effect.

[0031] Piston drive mechanism

[0032] Preferably, such as Figures 4-6 As shown, the piston drive mechanism is specifically a piston drive mechanism for a pressure relief valve, including a valve cover 2, a piston 3, a valve stem 10, a spring 4, and a bellows 7; the valve cover 2 includes a cover plate, a first receiving section 2.2, and a second receiving section 2.3 connected in sequence; the cover plate is installed at the inlet end of the pressure relief valve body 5; a first receiving cavity for accommodating the piston 3 is opened in the first receiving section 2.2, and a second receiving cavity for accommodating the valve stem 10 and the spring 4 is opened in the second receiving section 2.3, with the spring 4 mounted on the valve stem 10; the first receiving cavity and the second receiving cavity are coaxial and The piston 3 is sealed to the first receiving cavity; the front end of the valve stem 10 is connected to the piston 3, and the rear end of the valve stem 10 passes through the second receiving cavity and is connected to the valve knife structure 8 of the pressure relief valve; the bellows 7 is coaxially sleeved outside the second receiving section 2.3 of the valve cover 2, and the second receiving section 2.3 has a through hole that connects the second receiving cavity and the bellows 7. The pressure in the second receiving cavity is the same as the internal pressure of the bellows 7; the front end of the bellows 7 is connected to the first receiving section 2.2 of the valve cover 2 through the first support ring 6, and the rear end of the bellows 7 is connected to the center seat 8.1 through the second support ring 9.

[0033] In this invention, the first receiving cavity of the valve cover 2 is sealed with an O-ring between it and the piston 3; the second receiving cavity of the valve cover 2 is also a spring cavity, bearing the load of the spring 4 when the valve is actuated. In this invention, the bellows 7 is made of metal material, ensuring cavity sealing while also possessing good performance. The bellows 7 is sealed to the first support ring 6 and the second support ring 9 by a sealing weld. The first support ring 6 is sealed to the first receiving section 2.2 of the valve cover 2, and the second support ring 9 is sealed to the valve knife structure 8 by O-rings, ensuring isolation between the internal and external media of the bellows 7. The first support ring 6 is bolted to the first receiving section 2.2 of the valve cover 2, and the second support ring 9 is bolted to the valve knife structure 8.

[0034] In this invention, spring 4 is connected to valve stem 10 via spring seat 14. When valve stem 10 moves axially within the second receiving cavity, the length of spring 4 changes accordingly. The starting pressure is set by adjusting the preload of spring 4, and spring seat 14 ensures that the piston drive mechanism meets the anti-vibration and shock performance requirements. In this invention, spring 4 also serves a reset function. After the rupture diaphragm 11 is cut, the pressure inside the containment has been released, and the pressure inside and outside the bellows 7 is nearly balanced. Under the spring force of spring 4, valve knife structure 8 returns to its original position.

[0035] In this invention, the pressure inside the containment acts on the surface of the piston 3. When the pressure in the containment rises to a set value, a certain pressure difference will be formed inside and outside the bellows 7. The pressure acts on the surface of the piston 3. After the force overcomes the frictional force formed by the valve knife structure 8, the frictional force of the O-ring at the piston 3 and the spring force, the valve stem 10 stretches the bellows 7 and pushes the valve knife structure 8 to move towards the burst diaphragm 11 until the burst diaphragm 11 is cut off, and the two ends of the valve are connected, thereby realizing the rapid depressurization of the containment.

[0036] Preferably, the piston 3 is further provided with an internal pressure discharge mechanism 13; the internal pressure discharge mechanism 13 includes a threaded sleeve, a valve disc and a spring, the piston 3 has a discharge hole, the threaded sleeve is disposed inside the discharge hole, the spring is disposed outside the threaded sleeve, the valve disc is located at the outer port of the discharge hole, and the valve disc is connected to one end of the spring.

[0037] In this invention, when the compressed volume formed by the piston 3's movement is greater than the increased volume caused by the valve structure 8's forward movement pulling up the bellows 7, the internal pressure of the bellows 7 will rise. The internal pressure relief mechanism 13, designed on the piston 3, can open the valve to release some of the gas from the bellows 7's internal cavity when the internal pressure rises to a threshold, thus maintaining the internal pressure within the threshold. In this invention, the internal pressure relief mechanism 13 is a conventional structure and will not be described in detail here.

[0038] Preferably, the first receiving section 2.2 is connected to the middle of the cover plate, and the edge of the cover plate is provided with a plurality of waist-shaped holes 2.1.

[0039] In this invention, the waist-shaped holes 2.1 are evenly distributed, and the total area of ​​the waist-shaped holes 2.1 is greater than the flow cross-sectional area of ​​the pressure relief valve (that is, the total flow area of ​​the end interface pipeline of the discharge valve), ensuring that the flow capacity of the discharge valve meets the design requirements.

[0040] Preferably, the end of the bellows 7 is provided with a one-way exhaust valve for discharging the gas inside the bellows 7. When the external pressure of the bellows 7 increases, the internal pressure of the bellows 7 can still be maintained at one atmosphere, ensuring the pressure difference between the outside and inside of the bellows 7.

[0041] Preferably, the inlet end (i.e. the front end) of the first receiving cavity is connected to an orifice plate 1, and the orifice plate 1 has an overflow hole 1.1.

[0042] Valve knife structure 8

[0043] As shown in Figure 7, a valve knife structure 8 for a pressure relief valve is specifically a triangular knife-type valve knife structure for a pressure relief valve, including a cylinder 8.3, a center seat 8.1, connecting ribs 8.2, and a blade 8.4; the rear end of the valve stem 10 and the rear end of the bellows 7 are both connected to the center seat 8.1; multiple connecting ribs 8.2 are provided, with the inner ends of each connecting rib 8.2 connected to the center seat 8.1, and arranged radially along the outer periphery of the center seat 8.1; the outer ends of the connecting ribs 8.2 are connected to the inner wall of the cylinder 8.3, and the cylinder 8.3 is assembled at the outlet end of the valve body 5 of the pressure relief valve; the blade 8.4 is connected to the outer side of the connecting ribs 8.2.

[0044] In this invention, the central seat 8.1 has a disc-shaped structure.

[0045] In this invention, there are three connecting stiffeners 8.2. A flow channel is formed between two adjacent connecting stiffeners 8.2. The total area of ​​the flow channel between the three connecting stiffeners 8.2 is greater than the total cross-sectional area of ​​the pressure relief valve (that is, the flow cross-section of the end interface pipe of the pressure relief valve), ensuring that the valve flow capacity meets the design requirements.

[0046] In this invention, the central seat 8.1 is connected to three connecting stiffeners 8.2, and three blades 8.4 are correspondingly configured. The blades 8.4 are formed by grinding the edges of the connecting stiffeners 8.2. The cutting direction of the blades 8.4 is directly opposite to the rupture diaphragm 11 of the pressure relief valve, ensuring that the rupture diaphragm 11 is cut off when the valve is activated.

[0047] Preferably, the inner end of the blade 8.4 (corresponding to the end where the connecting rib plate 8.2 is connected to the center seat 8.1) protrudes relative to the outer end, and the inner ends of the three blades 8.4 are connected to form a conical structure.

[0048] In this invention, when the valve knife structure 8 moves toward the rupture diaphragm 11 of the pressure relief valve, the central cone of the conical structure first contacts the rupture diaphragm 11, piercing the rupture diaphragm 11 from the center; after the central cone of the conical structure pierces the rupture diaphragm 11, it continues to move axially until the blade 8.4 cuts the rupture diaphragm 11 into three parts, and the valve knife squeezes the broken diaphragm onto the inner wall of the valve seat 12, which ensures that the diaphragm is completely broken and does not affect the downstream flow.

[0049] Preferably, the cylinder 8.3 includes a large-diameter section 8.6, a small-diameter section 8.8, and a tapered section 8.7 connecting the large and small-diameter sections 8.8; the large-diameter section 8.6 is adapted to the inner wall of the pressure relief valve body 5; the small-diameter section 8.8 is adapted to the guide boss 5.1 located inside the valve body 5.

[0050] In this invention, a double-guide structure is adopted between the cylinder 8.3 and the valve body 5 of the pressure relief valve to ensure that the valve knife structure 8 will not get stuck with the contacting parts when it is working.

[0051] Preferably, the outer wall surface of the large-diameter section 8.6 of the cylinder 8.3 is a guide surface, and the guide surface is provided with multiple slots 8.5, the direction of which is parallel to the axial direction of the cylinder 8.3. The design of the slots 8.5 in this invention ensures that no vacuum cavity is formed when compression occurs between the valve knife structure 8 and the valve body 5, and the intermediate medium can be discharged outward through the slots 8.5 without affecting the operating speed of the valve knife structure 8.

[0052] The working principle of this invention is as follows: When an accident occurs, the pressure inside the containment instantly rises to a set value, creating a pressure difference between the inside and outside of the bellows 7. This pressure acts on the surface of the piston 3. After overcoming the frictional force generated by the valve knife structure 8, the frictional force of the O-ring at the piston 3, and the spring force, the valve stem 10 of the piston drive mechanism pushes the valve knife structure 8 towards the rupture diaphragm 11 until the diaphragm is cut off and ruptured. This connects the two ends of the pressure relief valve, thereby achieving rapid depressurization of the containment. After the rupture diaphragm 11 is cut off, since the pressure in the pressurized gas space has been released, the pressure inside and outside the bellows 7 is nearly balanced. Under the action of the spring force of the spring 4, the valve knife structure 88 returns to its original position.

[0053] The above description is merely a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. Therefore, any equivalent or modified versions made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A pressure relief valve, characterized in that, The pressure relief valve is used for depressurizing the containment vessel; it includes a valve body, a rupture diaphragm, a piston drive mechanism, a valve knife structure, and a valve seat. The valve body is hollow inside, and the piston drive mechanism, valve knife structure, and rupture diaphragm are coaxially installed inside the valve body in sequence. The valve seat is installed at the outlet end of the valve body. The drive end of the piston drive mechanism is connected to the valve knife structure, and the rupture diaphragm is located at the outlet of the valve body to seal the outlet channel of the valve body. The piston drive mechanism includes a valve cover, a piston, a valve stem, a return spring, and a bellows. The valve cover includes a cover plate, a first receiving section, and a second receiving section connected in sequence. The cover plate is installed at the inlet end of the valve body. The first receiving section has a first receiving cavity for accommodating the piston, and the second receiving section has a second receiving cavity for accommodating the valve stem and the return spring. The return spring is mounted on the valve stem. The first receiving cavity and the second receiving cavity are coaxial and connected. The piston is sealed to the first receiving cavity. The front end of the valve stem is connected to the piston, and the rear end of the valve stem extends through the second receiving cavity and is connected to the valve knife structure. The bellows is coaxially sleeved outside the second receiving section of the valve cover. The second receiving section has a through hole connecting the second receiving cavity and the bellows. The pressure in the second receiving cavity is the same as the pressure inside the bellows. The front end of the bellows is connected to the first receiving section of the valve cover through a first support ring, and the rear end of the bellows is connected to the center seat through a second support ring. The cover plate has multiple oblong holes on its edge, and the total area of ​​the oblong holes is greater than the flow cross-sectional area of ​​the pressure relief valve. The bellows end is equipped with a one-way exhaust valve to discharge the gas inside the bellows. When the external pressure of the bellows increases, the internal pressure of the bellows is kept at one atmosphere to ensure the pressure difference between the outside and inside of the bellows. The pressure relief valve is a containment pressure relief valve, which is connected to the internal space of the containment. The pressure inside the containment acts on the piston surface. When the pressure inside the containment rises to a set value, a pressure difference is formed inside and outside the bellows. The pressure acts on the piston surface. After the force overcomes the friction and spring force, the valve stem stretches the bellows and pushes the valve knife structure to move towards the burst diaphragm until the burst diaphragm is cut off.

2. The pressure relief valve as described in claim 1, characterized in that, The inlet end of the first receiving cavity is connected to an orifice plate, and the orifice plate has flow holes.

3. The pressure relief valve as described in claim 1, characterized in that, The reset spring is connected to the valve stem via a spring seat.

4. The pressure relief valve as described in claim 1, characterized in that, The piston is also provided with an internal pressure discharge mechanism; the internal pressure discharge mechanism includes a threaded sleeve, a valve disc and a spring. The piston has a discharge hole, the threaded sleeve is installed inside the discharge hole, the spring is installed outside the threaded sleeve, the valve disc is located at the outer port of the discharge hole, and the valve disc is connected to one end of the spring.

5. The pressure relief valve as described in claim 1, characterized in that, The first receiving cavity of the valve cover is sealed with an O-ring between itself and the piston.

6. The pressure relief valve as described in claim 1, characterized in that, The corrugated pipe is made of metal.

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