A pilot safety valve

Abstract

The present invention relates to a pilot-operated safety valve, comprising a main valve, a first pilot valve for controlling the opening and closing of a second pilot valve, and a second pilot valve for controlling the opening and closing of the main valve, wherein the main valve flap has a plane, a plane is formed at the main outlet of the main valve body, and when the main valve is closed, the plane of the main valve flap is directly in contact with the plane of the main outlet; the first valve flap has a plane, a plane is formed at the first outlet of the first valve body, and when the first pilot valve is closed, the plane of the first valve flap is directly in contact with the plane of the first outlet; the second valve flap has a plane, a plane is formed at the second outlet of the second valve body, and when the second pilot valve is closed, the plane of the second valve flap is directly in contact with the plane of the second outlet. The pilot valve of the present invention adopts a two-stage control structure, with stable action and reliable performance. The action of the main valve is controlled by the two-stage pilot valve, and can be applied under large-caliber and high-pressure working conditions. The valve flap adopts a self-sealing structure, with better sealing performance, and does not use non-metallic materials as sealing materials, so that the working temperature range is expanded.

Description

Technical Field

[0001] The invention relates to the field of safety valves, and in particular to a pilot-operated safety valve. Background Art

[0002] As an automatic pressure relief device, the safety valve is widely used in pressure vessels and pressure pipelines. When the system pressure exceeds the set pressure of the safety valve, the safety valve drives the valve to open through its own medium and discharges the medium that causes the overpressure. When the system pressure drops to a safe range, the valve automatically closes. The safety valve achieves overpressure protection for pressure vessels and pressure pipelines through the discharge process.

[0003] Safety valves widely used in chemical, thermal power, nuclear power and other industries include spring-loaded safety valves and pilot-operated safety valves. Spring-loaded safety valves seal the medium through the force of the spring, while pilot-operated safety valves seal the medium through the self-force of the medium. Compared with spring-loaded safety valves, pilot-operated safety valves are lighter, smaller, and have stronger discharge capacity. The self-sealing working principle of the main valve enables the main valve to have better sealing under high working pressure conditions.

[0004] Most pilot-operated safety valves mainly include a main valve and a pilot valve. The main valve structure seals the medium through the self-force of the medium. When the system pressure rises to the set pressure, the pilot valve opens and discharges the medium used for self-sealing inside the main valve. The sealing force of the main valve disappears and the main valve opens.

[0005] The establishment of the self-sealing force of the main valve of the existing pilot-operated safety valve is mainly achieved through the elastic seal between the main valve disc and the valve body. For example, Chinese patents CN104514901A, CN106402444A, CN111734860A, CN202220890U, CN101963251A, CN105864496A, etc. all use non-metallic materials (rubber O-rings, plastic spring energy storage rings) as sealing components. The use of rubber O-rings results in that such pilot-operated safety valves can only be used in the operating range of -40°C to 300°C. Even if the lower temperature limit can be appropriately lowered when using a plastic spring energy storage ring, the operating temperature range of the safety valve is still limited. Summary of the invention

[0006] The object of the present invention is to provide a pilot operated safety valve which can provide a wider operating temperature range.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A pilot-operated safety valve has a main inlet and a main outlet. The safety valve comprises a main valve and a pilot valve. The pilot valve comprises a first pilot valve and a second pilot valve. The first pilot valve is used to control the opening and closing of the second pilot valve. The second pilot valve is used to control the opening and closing of the main valve.

[0009] The main valve comprises a main valve body and a main valve disc arranged in the main valve body. The main valve body has a main inlet, a main outlet and a first connecting port. The main inlet is connected to the total inlet, the main outlet is connected to the total outlet, the first connecting port is connected to the second pilot valve, the main outlet and the first connecting port are located on both sides of the main valve disc, the main valve disc can move between the main outlet and the first connecting port to open and close the main outlet, the main valve disc has a plane, and a plane is formed at the main outlet of the main valve body. When the main valve is closed, the plane of the main valve disc directly fits the plane of the main outlet.

[0010] The first pilot valve comprises a first valve body, a first valve disc arranged in the first valve body, and a first auxiliary opening and closing component connected to the first valve disc, the first valve body has a first inlet and a first outlet, the first inlet is connected to the main inlet, the first outlet is connected to the second pilot valve, the first valve disc has a plane, and a plane is formed at the first outlet of the first valve body, and when the first pilot valve is closed, the plane of the first valve disc is directly attached to the plane of the first outlet;

[0011] The second pilot valve includes a second valve body, a second valve disc arranged in the second valve body, and a second auxiliary opening and closing component connected to the second valve disc. The second valve body has a second inlet, a second outlet, and a second connecting port. The second inlet is connected to the first outlet, the second outlet is connected to the outside, and the second connecting port is connected to the first connecting port. The second valve disc has a plane, and a plane is formed at the second outlet of the second valve body. When the second pilot valve is closed, the plane of the second valve disc is directly in contact with the plane of the second outlet.

[0012] Preferably, a clearance fit is adopted between the main valve body and the first valve flap, so as to ensure that the main valve flap moves smoothly in the main valve body.

[0013] Further preferably, the flow area of ​​the gap is smaller than the maximum flow area after the second pilot valve is opened, otherwise the main valve flap cannot be closed after opening.

[0014] Preferably, the main valve flap is provided with an internal passage, and the main inlet is connected to the first communication port through the internal passage.

[0015] Further preferably, the flow area of ​​the internal passage is smaller than the maximum flow area after the second pilot valve is opened, otherwise the main valve flap cannot be closed after opening.

[0016] Preferably, the first auxiliary opening and closing component includes a bellows, a first elastic member, and an adjusting member for adjusting the elastic force of the first elastic member, one end of the bellows is connected to the first valve flap, and the other end is connected to the first valve body, one end of the first elastic member is connected to the first valve flap, and the other end is connected to the first valve body, and the adjusting member is connected between the other end of the first elastic member and the first valve body.

[0017] Preferably, the second valve body includes a first valve cavity and a second valve cavity, the second connecting port is opened on the cavity wall of the first valve cavity, the second valve flap is located in the first valve cavity, the first valve cavity and the second valve cavity are connected through the second outlet, the second inlet is opened on the cavity wall of the second valve cavity, a third outlet is opened on the second valve cavity, and the second outlet is connected to the outside of the safety valve through the third outlet.

[0018] Further preferably, the second auxiliary opening and closing assembly includes a second elastic member and a piston member, one end of the second elastic member is connected to the second valve flap, and the other end is connected to the cavity wall of the first valve cavity, one end of the piston member is located in the second valve cavity, and the other end is used to push the second valve flap to open and close the second outlet.

[0019] More preferably, a clearance fit is adopted between the piston member and the second valve chamber, so as to ensure that the piston moves smoothly in the main valve body.

[0020] More preferably, a blocking portion is provided in the second valve chamber, one end of the piston member is located on one side of the blocking portion, and the second outlet and the third outlet are both located on the other side of the blocking portion.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] The pilot valve of the present invention adopts a two-stage control structure, the pilot valve has stable action and reliable performance, the main valve action process can be applied under large-caliber and high-pressure conditions through the two-stage pilot valve control, the valve disc adopts a self-sealing structure with better sealing performance than the conventional pilot valve structure (direct spring force sealing), and does not use non-metallic materials (rubber O-rings, plastic spring energy storage rings, etc.) as sealing materials, which can expand the working temperature range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 It is a structural schematic diagram of this embodiment.

[0024] In the above drawings: 11, main inlet; 12, main outlet; 2, main valve body; 21, main inlet, 22, main outlet; 23, first connecting port; 24, main valve seat; 3, main valve disc; 31, internal channel; 4, first valve body; 41, first inlet; 42, first outlet; 43, first valve seat; 5, first valve disc; 61, bellows; 62, first elastic member; 63, adjusting member; 7, second valve body; 71, first valve cavity; 72, second valve cavity; 73, blocking portion; 74, second inlet; 75, second outlet; 76, third outlet; 77, second connecting port; 78, second valve seat; 8, second valve disc; 91, second elastic member; 92, piston member; 93, annular groove. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] like Figure 1As shown, a pilot-operated safety valve has a main inlet 11 and a main outlet 12. The safety valve includes a main valve and a pilot valve. The pilot valve includes a first pilot valve and a second pilot valve. The first pilot valve is used to control the opening and closing of the second pilot valve. The second pilot valve is used to control the opening and closing of the main valve. The whole valve adopts a modular design with a compact structure and a small size. In this embodiment, the safety valve is as follows Figure 1 The horizontal setting shown is used for explanation. When used in practice, the safety valve can be installed at a different angle according to the specific working environment.

[0029] The main valve adopts a self-sealing structure, including a main valve body 2, a main valve disc 3 arranged in the main valve body 2, a main valve seat 24 matched with the main valve disc 3 is formed on the main valve body 2, the main valve body 2 has a main inlet 21, a main outlet 22, and a first communication port 23, the main outlet 22 is located on the main valve seat 24, the main inlet 21 is connected to the main inlet 11, the main outlet 22 is connected to the main outlet 12, the first communication port 23 is connected to the second pilot valve, the main outlet 22 and the first communication port 23 are located on both sides of the main valve disc 3, the main valve disc 3 can move between the main outlet 22 and the first communication port 23 to open and close the main outlet 22, in this embodiment, the main valve disc 3 moves in the vertical direction. The main valve disc 3 has a plane, and a plane is formed at the main outlet 22 of the main valve body 2. In this embodiment, the plane of the main valve disc 3 is a horizontal plane, and the plane formed at the main outlet 22 of the main valve body 2 is also a horizontal plane. When the main valve is closed, the plane of the main valve flap 3 directly fits the plane of the main outlet 22, and the sealing pressure on the main valve flap 3 is perpendicular to the plane of the main valve flap 3 and the plane of the main outlet 22. The main valve body 2 and the first valve flap 5 are matched with a clearance, which can ensure that the main valve flap 3 moves smoothly in the main valve body 2. The flow area of ​​the clearance is smaller than the maximum flow area after the second pilot valve is opened, otherwise the main valve flap 3 cannot be closed after opening. The main valve flap 3 is provided with an internal channel 31, the main inlet 21 and the main outlet 22 are located on the same side of the main valve flap 3, and the main inlet 21 is connected to the first connecting port 23 through the internal channel 31. The flow area of ​​the internal channel 31 is smaller than the maximum flow area after the second pilot valve is opened, otherwise the main valve flap 3 cannot be closed after opening. The end face of the main valve flap 3 facing the main outlet 22 is smaller than the end face of the main valve flap 3 facing the first connecting port 23, and the space between the main valve flap 3 and the first valve body 4 facilitates the medium to flow from the main inlet 21 to the internal channel 31. Therefore, the sum of the gap between the main valve disc 3 and the main valve body 2 and the flow area of ​​the internal channel 31 of the main valve disc 3 is smaller than the maximum flow area after the second pilot valve is opened, forming a pressure difference to discharge the overpressure medium.

[0030] The first pilot valve includes a first valve body 4, a first valve flap 5 disposed in the first valve body 4, and a first auxiliary opening and closing assembly connected to the first valve flap 5. A first valve seat 43 matching with the first valve flap 5 is formed on the first valve body 4. The first valve body 4 has a first inlet 41 and a first outlet 42. The first outlet 42 is located on the first valve seat 43. The first inlet 41 is connected to the main inlet 11, and the first outlet 42 is connected to the second pilot valve. In this embodiment, the first valve flap 5 moves in a vertical direction. The first valve flap 5 has a plane, and a plane is formed at the first outlet 42 of the first valve body 4. In this embodiment, the plane of the first valve flap 5 is a horizontal plane, and the plane formed at the first outlet 42 of the first valve body 4 is also a horizontal plane. When the first pilot valve is closed, the plane of the first valve flap 5 directly fits the plane of the first outlet 42, and the sealing pressure on the first valve flap 5 is perpendicular to the plane of the first valve flap 5 and the plane of the first outlet 42. The first auxiliary opening and closing assembly includes a bellows 61, a first elastic member 62, and an adjusting member 63 for adjusting the elastic force of the first elastic member 62. Usually, the first elastic member 62 can be a spring, and the adjusting member 63 can be an adjusting screw. The adjusting screw directly adjusts the compression of the spring, which can change the force balance between the bellows 61 and the first elastic member 62 under the force of the medium, and finally realizes the control of different opening pressures of the safety valve. One end of the bellows 61 is connected to the first valve flap 5, and the other end is connected to the first valve body 4. One end of the first elastic member 62 is connected to the first valve flap 5, and the other end is connected to the first valve body 4. The adjusting member 63 is connected between the other end of the first elastic member 62 and the first valve body 4. The first elastic member 62 is arranged in the bellows 61, and the bellows 61 can make the pressure sensing more accurate.

[0031] The second pilot valve includes a second valve body 7, a second valve flap 8 arranged in the second valve body 7, and a second auxiliary opening and closing component connected to the second valve flap 8. The second valve body 7 includes a first valve cavity 71 and a second valve cavity 72. The second valve flap 8 is located in the first valve cavity 71. A second valve seat 78 matching the second valve flap 8 is formed on the first valve cavity 71. The second valve body 7 has a second inlet 74, a second outlet 75, a third outlet 76, and a second connecting port 77. The second outlet 75 is located on the second valve seat 78. The second inlet 74 is opened in the second valve cavity 72. On the cavity wall, the second outlet 75 is located between the first valve cavity 71 and the second valve cavity 72, and the first valve cavity 71 and the second valve cavity 72 are connected through the second outlet 75. The third outlet 76 is provided on the cavity wall of the second valve cavity 72. The second communication port 77 is provided on the cavity wall of the first valve cavity 71. The second inlet 74 is connected to the first outlet 42. The second outlet 75 is connected to the outside of the safety valve through the third outlet 76. The second communication port 77 is connected to the first communication port 23. In this embodiment, the second valve flap 8 moves in the vertical direction. The second valve flap 8 has a plane, and a plane is formed at the second outlet 75 of the second valve body 7. In this embodiment, the plane of the second valve flap 8 is a horizontal plane, and the plane formed at the second outlet 75 of the second valve body 7 is also a horizontal plane. When the second pilot valve is closed, the plane of the second valve flap 8 directly fits the plane of the second outlet 75, and the sealing pressure on the second valve flap 8 is perpendicular to the plane of the second valve flap 8 and the plane of the second outlet 75. The second auxiliary opening and closing assembly includes a second elastic member 91 and a piston member 92. Usually, the second elastic member 91 is a spring. One end of the second elastic member 91 is connected to the second valve flap 8, and the other end is connected to the cavity wall of the first valve cavity 71. One end of the piston member 92 is located in the second valve cavity 72, and the other end is used to push the second valve flap 8 to open and close the second outlet 75. The other end of the piston member 92 can pass through the second outlet 75 to push the second valve flap 8. The piston member 92 and the second valve cavity 72 are matched with clearance to ensure that the piston moves smoothly in the main valve body 2. A blocking portion 73 is provided in the second valve cavity 72. One end of the piston member 92 and the second inlet 74 are located on one side of the blocking portion 73, and the second outlet 75 and the third outlet 76 are both located on the other side of the blocking portion 73. A plurality of annular grooves 93 are provided on the outer peripheral surface of one end of the piston member 92, and a plurality of annular grooves 93 are provided on the surface of the blocking portion 73 facing the piston member 92. The annular grooves 93 can interfere with the flow of the medium and increase the resistance when flowing out.

[0032] The main valve, the first pilot valve and the second pilot valve are all made of metal materials instead of non-metallic materials for sealing. The operating temperature range can reach -198℃~600℃, and can be used for overpressure protection of low-temperature, high-temperature, and high-pressure pressure vessels and pipelines.

[0033] The working principle of this embodiment is described in detail below (with Figure 1 The position relationship shown is taken as an example):

[0034] 1) Working status:

[0035] After the medium pressure enters from the main inlet 11, it is divided into two paths; one path of the medium enters the lower side of the main valve disc 3 in the main valve body 2 through the main inlet 21, and enters the upper side of the main valve disc 3 through the internal channel 31 of the main valve disc 3. The medium acts on the upper part of the main valve disc 3, and the main valve disc 3 is sealed with the main valve seat 24 under the action of pressure. The medium cannot be discharged from the main outlet 22 to the main outlet 12, and the gas on the upper side of the main valve disc 3 enters the first valve cavity 71 through the first connecting port 23 and the second connecting port 77, so that the second valve disc 8 is sealed with the second valve seat 78 under the action of the medium; the other path of the medium enters the first valve body 4 through the first inlet 41, and the bellows 61 generates a downward force under the joint action of the first elastic member 62 and the medium force. The force acts on the first valve disc 5 to seal the first valve disc 5 with the first valve seat 43.

[0036] 2) Set pressure working condition (valve open working condition):

[0037] When the system pressure rises to the set pressure, the medium force on the bellows 61 and the force of the first elastic member 62 are basically balanced. When the pressure continues to rise, the medium force on the bellows 61 is greater than the force of the first elastic member 62, and separation occurs between the first valve flap 5 and the first valve seat 43; after the medium in the first valve body 4 flows out from the first outlet 42, the medium enters the second valve chamber 72 from the second inlet 74, and the medium pushes the piston member 92 to move upward. After the piston member 92 moves upward, it contacts the bottom of the second valve flap 8. The upward force of the piston member 92 overcomes the force generated by the medium acting on the upper surface of the second valve flap 8, and the piston member 92 pushes the second valve flap 8 to move upward; after the second valve flap 8 moves upward, the medium flows out from the second outlet 75, and is discharged to the outside from the third outlet 76 under the restriction of the blocking member. The discharge of medium from the first valve chamber 71 directly leads to a decrease in the medium pressure on the upper side of the main valve body 2. The amount of medium that enters the space on the upper side of the main valve body 2 through the internal channel 31 of the main valve flap 3 and the gap between the main valve flap 3 and the main valve body 2 is less than the amount of medium discharged to the outside from the first valve chamber 71. The pressure in the space on the upper side of the main valve body 2 continues to decrease. The main valve flap 3 opens under the action of the upper and lower pressure differences. The medium that enters the safety valve from the main inlet 11 is directly discharged from the main inlet 21 through the main outlet 22 and then from the main outlet 12. The pressure of the protected pressure system continues to decrease.

[0038] iii) Valve closed:

[0039] When the pressure of the protected pressure system drops to the set value, the pressure of the medium entering the total inlet 11 decreases, the medium force on the bellows 61 is less than the force of the first elastic member 62, the first valve flap 5 and the first valve seat 43 are re-sealed, and the medium in the second valve chamber 72 is discharged to the third outlet 76 through the gap between the piston member 92 and the second valve body 7, the medium pressure in the second valve chamber 72 decreases, the piston member 92 falls back, the second valve flap 8 falls back, the second valve flap 8 and the second valve seat 78 are re-sealed, the medium pressure in the upper space of the main valve body 2 no longer decreases, the medium enters the upper space of the main valve body 2 through the internal channel 31 of the main valve flap 3, the pressure in the upper space of the main valve body 2 increases, the main valve flap 3 falls downward under the action of the upper medium pressure and seals with the main valve seat 24, and the safety valve is re-sealed.

[0040] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A pilot-operated safety valve, having a main inlet and a main outlet, the safety valve comprising a main valve and a pilot valve, the pilot valve comprising a first pilot valve and a second pilot valve, the first pilot valve being used to control the opening and closing of the second pilot valve, the second pilot valve being used to control the opening and closing of the main valve, characterized in that: The main valve comprises a main valve body and a main valve disc arranged in the main valve body. The main valve body has a main inlet, a main outlet and a first connecting port. The main inlet is connected to the total inlet, the main outlet is connected to the total outlet, the first connecting port is connected to the second pilot valve, the main outlet and the first connecting port are located on both sides of the main valve disc, the main valve disc can move between the main outlet and the first connecting port to open and close the main outlet, the main valve disc has a plane, and a plane is formed at the main outlet of the main valve body. When the main valve is closed, the plane of the main valve disc directly fits the plane of the main outlet. The first pilot valve comprises a first valve body, a first valve disc arranged in the first valve body, and a first auxiliary opening and closing component connected to the first valve disc, the first valve body has a first inlet and a first outlet, the first inlet is connected to the main inlet, the first outlet is connected to the second pilot valve, the first valve disc has a plane, and a plane is formed at the first outlet of the first valve body, and when the first pilot valve is closed, the plane of the first valve disc is directly attached to the plane of the first outlet; The second pilot valve includes a second valve body, a second valve disc arranged in the second valve body, and a second auxiliary opening and closing component connected to the second valve disc. The second valve body has a second inlet, a second outlet, and a second connecting port. The second inlet is connected to the first outlet, the second outlet is connected to the outside, and the second connecting port is connected to the first connecting port. The second valve disc has a plane, and a plane is formed at the second outlet of the second valve body. When the second pilot valve is closed, the plane of the second valve disc is directly in contact with the plane of the second outlet.

2. The pilot operated safety valve according to claim 1, characterized in that: The main valve body and the first valve disc are clearance-fitted.

3. The pilot operated safety valve according to claim 2, characterized in that: The flow area of ​​the gap is smaller than the maximum flow area after the second pilot valve is opened.

4. The pilot operated safety valve according to claim 1, characterized in that: The main valve flap is provided with an internal passage, and the main inlet is connected with the first communication port through the internal passage.

5. The pilot operated safety valve according to claim 4, characterized in that: The flow area of ​​the internal passage is smaller than the maximum flow area after the second pilot valve is opened.

6. The pilot operated safety valve according to claim 1, characterized in that: The first auxiliary opening and closing component includes a bellows, a first elastic member, and an adjusting member for adjusting the elastic force of the first elastic member, one end of the bellows is connected to the first valve flap, and the other end is connected to the first valve body, one end of the first elastic member is connected to the first valve flap, and the other end is connected to the first valve body, and the adjusting member is connected between the other end of the first elastic member and the first valve body.

7. The pilot operated safety valve according to claim 1, characterized in that: The second valve body includes a first valve cavity and a second valve cavity, the second connecting port is opened on the cavity wall of the first valve cavity, the second valve disc is located in the first valve cavity, the first valve cavity and the second valve cavity are connected through the second outlet, the second inlet is opened on the cavity wall of the second valve cavity, a third outlet is opened on the second valve cavity, and the second outlet is connected to the outside of the safety valve through the third outlet.

8. The pilot operated safety valve according to claim 7, characterized in that: The second auxiliary opening and closing component includes a second elastic member and a piston member. One end of the second elastic member is connected to the second valve flap, and the other end is connected to the cavity wall of the first valve cavity. One end of the piston member is located in the second valve cavity, and the other end is used to push the second valve flap to open and close the second outlet.

9. The pilot operated safety valve according to claim 8, characterized in that: The piston member and the second valve chamber are clearance-matched.

10. The pilot operated safety valve according to claim 8, characterized in that: A blocking portion is arranged in the second valve cavity, one end of the piston member is located on one side of the blocking portion, and the second outlet and the third outlet are both located on the other side of the blocking portion.

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