A pilot operated safety valve for hydrogen

Abstract

This utility model provides a pilot-operated safety valve for hydrogen, relating to the technical field of safety protection equipment for natural gas collection and transmission pipelines. It includes a main valve and a pilot valve. The main valve comprises a main valve body, main valve seat, main valve core, main valve sleeve, and main valve cover, all forged from 304 stainless steel. The main valve body is integrally forged. A metal-graphite spiral wound gasket is used for sealing between the main valve cover and the main valve sleeve, and between the main valve sleeve and the main valve body. A metal-graphite spiral wound gasket is also used for sealing between the main valve seat and the main valve body. The pilot valve comprises a pilot valve seat, pilot valve disc, pilot valve stem, lower valve body, upper valve body, and pilot valve cover, all forged from 304 stainless steel. A metal-graphite spiral wound gasket is used for sealing between the lower and upper valve bodies, and between the upper valve body and the pilot valve cover. This valve is suitable for hydrogen transmission.

Description

Technical Field

[0001] This utility model relates to the technical field of safety protection equipment for natural gas collection and transmission pipelines, and more specifically to a pilot-operated safety valve for hydrogen. Background Technology

[0002] As a key device in industrial safety protection, pilot-operated safety valves typically consist of a main valve and a pilot valve. Their core working mechanism involves the pilot valve controlling the opening and closing of the main valve: when the pressure of the medium in the system exceeds a preset value, the pilot valve opens first, and with the aid of a power transmission auxiliary device, drives the main valve to operate, achieving medium discharge and system depressurization. Compared to traditional spring-loaded safety valves, pilot-operated structures have significant advantages such as high pressure setting accuracy, large discharge coefficient, strong sealing reliability, and immunity to back pressure interference, and are widely used in high-pressure operating scenarios such as petrochemicals and energy power.

[0003] With the rapid development of the hydrogen energy industry, there is an urgent need for safety devices adapted to hydrogen as a medium in fields such as hydrogen refueling stations and hydrogen fuel cell supply systems. Hydrogen, as a special medium, has a molecular diameter of only 0.289 nm and a permeability more than three times that of methane, making it extremely prone to leakage through material pores or structural gaps. Simultaneously, the accumulation of hydrogen at the grain boundaries of metallic materials can cause hydrogen embrittlement, leading to a decrease in material strength or even cracking. Tests have shown that the embrittlement resistance of ordinary carbon steel can decrease by more than 60% in a hydrogen environment. Furthermore, there is an explosion risk when the concentration of hydrogen mixed with air reaches 4% to 75%, placing stringent requirements on the sealing reliability and explosion-proof performance of safety devices.

[0004] Existing conventional pilot-operated safety valves face multiple technical challenges when applied to hydrogen systems: the weld joints of traditional welded valve bodies are prone to becoming hydrogen permeation channels, and data shows that the hydrogen permeation of welded structures can be more than 50 times that of integral forged parts; ordinary sealing materials are prone to aging and failure in hydrogen environments, such as nitrile rubber, whose sealing performance degrades by more than 50% after one year of use in a hydrogen atmosphere; and materials not optimized for hydrogen embrittlement can lead to a significant reduction in the lifespan of valve internals.

[0005] In Chinese patent literature, application publication number CN111981168A, application publication date November 24, 2020, entitled "Prior Technology of a Pilot-Operated Safety Valve", has the characteristics of high-precision discharge, small reseating pressure difference and obvious sudden opening effect, but is not suitable for hydrogen transmission. Utility Model Content

[0006] To address the shortcomings of the existing technology, this utility model proposes a pilot-operated safety valve specifically for hydrogen, which is suitable for hydrogen transmission.

[0007] The technical solution of this utility model is as follows:

[0008] A pilot-operated safety valve for hydrogen includes a main valve and a pilot valve. The main valve and the pilot valve are connected by 304 stainless steel pipe fittings and sealed at the connection with radial fluororubber. The main valve includes a main valve body, a main valve seat, a main valve core, a main valve sleeve, and a main valve cover, all forged from 304 stainless steel. The main valve body is integrally forged, and the main valve seat, main valve core, main valve sleeve, and main valve spring are disposed within the main valve body.

[0009] A metal-graphite spiral wound gasket is installed between the main valve cover and the main valve sleeve; a metal-graphite spiral wound gasket is installed between the main valve sleeve and the main valve body; and a metal-graphite spiral wound gasket is installed between the main valve seat and the main valve body.

[0010] The pilot valve includes a pilot valve seat, a pilot valve disc, a pilot valve stem, a lower valve body, an upper valve body, and a pilot valve cover, all forged from 304 stainless steel. The pilot valve seat is placed inside the lower valve body, forming a closed chamber between the lower and upper valve bodies. A metal-graphite spiral wound gasket is provided between the lower and upper valve bodies for sealing. The pilot valve disc is connected to the pilot valve stem, which is placed inside the chamber. The upper end of the pilot valve stem extends out of the upper valve body and connects to the pilot valve spring inside the pilot valve cover. The upper valve body and the pilot valve cover are sealed by a metal-graphite spiral wound gasket.

[0011] Furthermore, the main valve seat is located within the main valve body, the main valve sleeve is located on the main valve seat, the main valve core is slidably located within the main valve sleeve, the lower end of the main valve core cooperates with the main valve seat to form a sealing pair, the upper end of the main valve core is connected to the main valve spring, the main valve cover is fixedly connected to the main valve body to fix the main valve sleeve within the main valve body, and the main valve spring is located between the main valve cover and the main valve core.

[0012] Furthermore, a pipe fitting I is provided on the main valve cover, which is connected to the upper chamber of the main valve. A pipe fitting II is provided at the inlet end of the main valve body, and a pipe fitting III is provided at the lower end of the lower valve body. An air duct for the upper chamber of the main valve is provided below the pilot valve disc. The air inlet channel of the pipe fitting III is connected to the air duct for the upper chamber of the main valve. The air inlet channel is connected to the pipe fitting II via a 304 stainless steel pipe fitting I. An air duct is provided on the lower valve body, with one end connected to the air duct for the upper chamber of the main valve and the other end connected to the pipe fitting I via a 304 stainless steel pipe fitting II.

[0013] Furthermore, the chamber is connected to a vent located on the lower valve body.

[0014] Furthermore, a piston is provided on the pilot valve stem, and the piston is placed in the chamber and moves with the pilot valve stem within the chamber; the piston and the lower valve body are sealed with a fluororubber O-ring.

[0015] Furthermore, the piston area is larger than the pilot valve disc area, and an exhaust damping hole is designed on the piston.

[0016] Furthermore, the pilot valve disc, piston, and pilot valve stem are a single unit.

[0017] The beneficial effects of this utility model are as follows:

[0018] 1. The main valve body is forged from 304 stainless steel as a whole, eliminating defects such as porosity, cracks, and lack of fusion in the weld joint of the transmission welded structure, preventing hydrogen penetration and the risk of hydrogen embrittlement at the weld joint.

[0019] 2. The metal internals of the main valve and pilot valve are forged from 304 stainless steel to enhance their resistance to corrosion and hydrogen embrittlement in hydrogen medium.

[0020] 3. By winding the metal graphite gasket with 304 stainless steel to prevent the gasket from deforming under pressure, the graphite layer fills the tiny gaps with its softness, forming a tight sealing surface. In addition, graphite has extremely low permeability, effectively blocking the permeation of hydrogen.

[0021] 4. The fittings connecting the pilot valve and the main valve are made of 304 stainless steel, and the joints are sealed with radial fluororubber, which strengthens the connection between the pilot valve and the main valve and the sealing of the connection position, preventing hydrogen leakage due to loosening of the connection. Attached Figure Description

[0022] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0023] Figure 2 This is a cross-sectional view of the pilot valve of this utility model.

[0024] Reference numerals: 1-Main valve, 2-Main valve body, 3-Main valve seat, 4-Main valve core, 5-Main valve sleeve, 6-Main valve spring, 7-Main valve cover, 8-Metal graphite spiral wound gasket, 9-Pipe fitting I, 10-Pipe fitting II, 11-Pipe fitting III, 12-304 stainless steel pipe fitting I, 13-304 stainless steel pipe fitting II, 14-Pilot valve, 15-Pilot valve seat, 16-Pilot valve disc, 17-Lower valve body, 18-Upper valve body, 19-Pilot valve cover, 20-Pilot valve spring, 21-Cavity, 22-Upper chamber of main valve, 23-Inlet passage, 24-Inlet passage of upper chamber of main valve, 25-Inlet pipe, 26-Piston, 27-Exhaust damping orifice, 28-Relief port, 29-Pilot valve stem. Detailed Implementation

[0025] Example 1

[0026] A pilot-operated safety valve for hydrogen includes a main valve 1 and a pilot valve 14. The main valve 1 and the pilot valve 14 are connected by 304 stainless steel pipe fittings and sealed at the connection by radial fluororubber. The main valve 1 includes a main valve body 2, a main valve seat 3, a main valve core 4, a main valve sleeve 5, and a main valve cover 7, all forged from 304 stainless steel. The main valve body 2 is integrally forged. The main valve seat 3, the main valve core 4, the main valve sleeve 5, and the main valve spring 6 are disposed inside the main valve body 2.

[0027] A metal-graphite spiral wound gasket 8 is provided between the main valve cover 7 and the main valve sleeve 5 for sealing; a metal-graphite spiral wound gasket 8 is provided between the main valve sleeve 5 and the main valve body 2 for sealing; a metal-graphite spiral wound gasket 8 is provided between the main valve seat 3 and the main valve body 2 for sealing.

[0028] The pilot valve 14 includes a pilot valve seat 15, a pilot valve disc 16, a pilot valve stem 29, a lower valve body 17, an upper valve body 18, and a pilot valve cover 19, all forged from 304 stainless steel. The pilot valve seat 15 is placed inside the lower valve body 17, forming a closed chamber 21 between the lower valve body 17 and the upper valve body 18. A metal-graphite wound gasket 8 is provided between the lower valve body 17 and the upper valve body 18 for sealing. The pilot valve disc 16 is connected to the pilot valve stem 29, which is placed inside the chamber 21. The upper end of the pilot valve stem 29 extends out of the upper valve body 18 and connects to the pilot valve spring 20 inside the pilot valve cover 19. The upper valve body 18 and the pilot valve cover 19 are sealed by the metal-graphite wound gasket 8.

[0029] Metal-graphite spiral wound gaskets are made of high-quality SUS304 or SUS316 ("V" or "W" shaped) metal strips and other alloy materials, interwoven with soft materials such as graphite, asbestos, PTFE, and asbestos-free materials in an alternating, overlapping spiral wound pattern. The metal strips are fixed at the beginning and end by spot welding. Metal-graphite spiral wound gaskets offer the best resilience among semi-metallic gaskets. Their structural density can be customized to meet different tightening force requirements, and the maximum compression is controlled using inner and outer steel rings. The surface finish requirements of the flange sealing surfaces contacted by the metal-graphite spiral wound gasket are not high. Metal-graphite spiral wound gaskets are particularly suitable for applications with uneven loads, easily loosened joints, periodic temperature and pressure changes, and impacts or vibrations. They are ideal static sealing components for flange connections in valves, pumps, heat exchangers, towers, manholes, handholes, etc.

[0030] In this embodiment, the main valve body 2 is integrally forged from 304 stainless steel, which eliminates defects such as porosity, cracks, and lack of fusion in the weld joint of the transmission welded structure, and prevents hydrogen permeation and the risk of hydrogen embrittlement at the weld joint.

[0031] The metal internals of the main valve 1 and the pilot valve 14 are forged from 304 stainless steel to enhance their resistance to corrosion and hydrogen embrittlement in hydrogen medium.

[0032] In this embodiment, the metal part of the metal graphite wound gasket 8 is made of SUS304 stainless steel. The 304 stainless steel prevents the gasket from deforming under pressure. The graphite layer fills the tiny gaps with its softness, forming a tight sealing surface. In addition, graphite has extremely low permeability, which effectively blocks the permeation of hydrogen.

[0033] The pipe fittings connecting the pilot valve 14 and the main valve 1 are made of 304 stainless steel, and the joint is sealed with radial fluororubber, which strengthens the connection between the pilot valve 14 and the main valve 1 and the sealing of the connection position, preventing hydrogen leakage due to loosening of the connection.

[0034] Example 2

[0035] This embodiment further elaborates and supplements the implementation of this utility model based on Embodiment 1.

[0036] The main valve seat 3 is located inside the main valve body 2, the main valve sleeve 5 is located on the main valve seat 3, the main valve core 4 is slidably located inside the main valve sleeve 5, the lower end of the main valve core 4 cooperates with the main valve seat 3 to form a sealing pair, the upper end of the main valve core 4 is connected to the main valve spring 6, the main valve cover 7 is fixedly connected to the main valve body 2 to fix the main valve sleeve 5 inside the main valve body 2, and the main valve spring 6 is located between the main valve cover 7 and the main valve core 4.

[0037] The main valve cover 7 is provided with a pipe fitting I9, which is connected to the upper chamber 22 of the main valve. The inlet end of the main valve body 2 is provided with a pipe fitting II10, and the lower end of the lower valve body 17 is provided with a pipe fitting III11. The pilot valve disc 16 is provided with an air intake channel 24 for the upper chamber of the main valve. The air intake channel 23 of the pipe fitting III11 is connected to the air intake channel 24 for the upper chamber of the main valve. The air intake channel 23 is connected to the pipe fitting II10 through a 304 stainless steel pipe fitting I12. The lower valve body 17 is provided with an air intake pipe 25, one end of which is connected to the air intake channel 24 for the upper chamber of the main valve, and the other end is connected to the pipe fitting I9 through a 304 stainless steel pipe fitting II13.

[0038] The chamber 21 is connected to the vent 28 located on the lower valve body 17.

[0039] The hydrogen pressure at the inlet of the main valve 1 acts on the lower part of the pilot valve disc 16 through the pipe fitting II10, the 304 stainless steel pipe fitting I12, the air inlet channel 23 and the air venting channel 24 of the upper chamber of the main valve. Since the pressure does not exceed the set value of the pilot valve spring 20, the pilot valve disc 16 remains stationary, the pilot valve 14 is in the closed state, the upper chamber 22 of the main valve is isolated from the outside, and the pressure remains stable.

[0040] The lower end of the main valve core 4 is tightly fitted with the main valve seat 3 to form a sealing pair. The main valve spring 6 applies downward pressure to the main valve core 4 to keep the main valve 1 closed. At this time, the hydrogen pressure at the inlet of the main valve 1 acts on the lower end of the main valve core 4 through the inside of the main valve body 2. However, due to the pressure difference between the upper and lower parts and the spring force of the main valve spring 6, the main valve 1 is kept closed.

[0041] When the hydrogen pressure at the inlet of main valve 1 continues to rise and exceeds the set value of pilot valve spring 20, the hydrogen pressure acting below pilot valve disc 16 overcomes the spring force of pilot valve spring 20, pilot valve disc 16 opens, pilot valve 14 opens, and the gas in the upper chamber 22 of main valve enters the upper chamber venting channel 24 of main valve below pilot valve disc 16 through pipe fitting joint I9, 304 stainless steel pipe fitting II13, and venting pipe 25, and is discharged through venting port 28. The pressure in the upper chamber 22 of main valve drops rapidly. At this time, the pressure difference between the upper and lower ends of main valve core 4 overcomes the resistance of main valve spring 6, pushing main valve core 4 to slide upward, main valve 1 opens, and hydrogen is discharged from the inlet of main valve 1 through the gap between main valve seat 3 and main valve core 4, and through the outlet of main valve 1, realizing system depressurization.

[0042] As hydrogen is discharged, the pressure at the inlet of main valve 1 gradually decreases, reducing the gas pressure acting on the lower part of pilot valve disc 16. When the pressure is lower than the set value of pilot valve spring 20, pilot valve disc 16 closes, pilot valve 14 closes, cutting off the pressure relief channel of the upper chamber 22 of main valve. After pilot valve 14 closes, the upper chamber 22 of main valve stops depressurizing. Hydrogen at the inlet of main valve 1 is supplied to the upper chamber 22 of main valve through pipe fitting joint II10, 304 stainless steel pipe fitting I12, air inlet channel 23, and upper chamber priming channel 24, priming pipe 25, 304 stainless steel pipe fitting II13, and pipe fitting joint I9. The combined force of the pressure in the upper chamber 22 of main valve and the spring force of main valve spring 6 is greater than the gas pressure at the lower end of main valve core 4, causing main valve core 4 to move downward and main valve 1 to close.

[0043] In this embodiment, the air intake tube is also forged from 304 stainless steel.

[0044] Example 3

[0045] This embodiment further elaborates and supplements the implementation of this utility model based on Embodiment 2.

[0046] A piston 26 is provided on the pilot valve stem 29. The piston 26 is placed in the chamber 21 and moves with the pilot valve stem 29 in the chamber 21. The piston 26 is sealed with the lower valve body 17 by a fluororubber O-ring.

[0047] The piston 26 has a larger area than the pilot valve disc 16, and an exhaust damping hole 27 is designed on the piston 26. When the pilot valve 14 discharges, the gas discharged from the pilot valve disc 16 is discharged through the exhaust damping hole 27 of the piston 26. At this time, there is a pressure difference between the upper and lower chambers of the piston 26. Under the amplification effect of the piston 26 area, when the pilot valve disc 16 opens, the gas will push the piston 26 to drive the pilot valve disc 16 to reach full opening instantly, which is conducive to the rapid release of gas in the upper chamber 22 of the main valve.

[0048] The pilot valve disc 16, piston 26, and pilot valve stem 29 are an integral unit.

Claims

1. A pilot-operated safety valve specifically for hydrogen, characterized in that: Includes a main valve (1) and a pilot valve (14), which are connected by 304 stainless steel pipe fittings and sealed with radial fluororubber at the connection. The main valve (1) includes a main valve body (2), a main valve seat (3), a main valve core (4), a main valve sleeve (5), and a main valve cover (7) forged from 304 stainless steel. The main valve body (2) is integrally forged. The main valve seat (3), the main valve core (4), the main valve sleeve (5), and the main valve spring (6) are disposed inside the main valve body (2). A metal-graphite spiral wound gasket (8) is provided between the main valve cover (7) and the main valve sleeve (5) for sealing; a metal-graphite spiral wound gasket (8) is provided between the main valve sleeve (5) and the main valve body (2); a metal-graphite spiral wound gasket (8) is provided between the main valve seat (3) and the main valve body (2). The pilot valve (14) includes a pilot valve seat (15), a pilot valve disc (16), a pilot valve stem (29), a lower valve body (17), an upper valve body (18), and a pilot valve cover (19) forged from 304 stainless steel. The pilot valve seat (15) is placed inside the lower valve body (17), and a closed chamber (21) is formed between the lower valve body (17) and the upper valve body (18). A metal graphite spiral wound gasket (8) is provided between the lower valve body (17) and the upper valve body (18) for sealing. The pilot valve disc (16) is connected to the pilot valve stem (29), and the pilot valve stem (29) is placed inside the chamber (21). The upper end of the pilot valve stem (29) extends out of the upper valve body (18) and is connected to the pilot valve spring (20) inside the pilot valve cover (19). The upper valve body (18) and the pilot valve cover (19) are sealed by the metal graphite spiral wound gasket (8).

2. The pilot-operated safety valve for hydrogen as described in claim 1, characterized in that: The main valve seat (3) is located inside the main valve body (2), the main valve sleeve (5) is located on the main valve seat (3), the main valve core (4) is slidably located inside the main valve sleeve (5), the lower end of the main valve core (4) cooperates with the main valve seat (3) to form a sealing pair, the upper end of the main valve core (4) is connected to the main valve spring (6), the main valve cover (7) is fixedly connected to the main valve body (2) to fix the main valve sleeve (5) inside the main valve body (2), and the main valve spring (6) is located between the main valve cover (7) and the main valve core (4).

3. A pilot-operated safety valve for hydrogen as described in claim 1 or 2, characterized in that: The main valve cover (7) is provided with a pipe fitting I (9), which is connected to the upper chamber (22) of the main valve. The inlet end of the main valve body (2) is provided with a pipe fitting II (10), and the lower end of the lower valve body (17) is provided with a pipe fitting III (11). The pilot valve disc (16) is provided with a main valve upper chamber air intake channel (24). The air intake channel (23) of the pipe fitting III (11) is connected to the main valve upper chamber air intake channel (24). The air intake channel (23) is connected to the pipe fitting II (10) through a 304 stainless steel pipe fitting I (12). The lower valve body (17) is provided with an air intake pipe (25). One end of the air intake pipe (25) is connected to the main valve upper chamber air intake channel (24), and the other end is connected to the pipe fitting I (9) through a 304 stainless steel pipe fitting II (13).

4. A pilot-operated safety valve for hydrogen as described in claim 1, characterized in that: The chamber (21) is connected to the vent (28) located on the lower valve body (17).

5. A pilot-operated safety valve for hydrogen as described in claim 3, characterized in that: A piston (26) is provided on the valve stem (29) of the pilot valve. The piston (26) is placed in the chamber (21) and moves with the valve stem (29) in the chamber (21). The piston (26) and the lower valve body (17) are sealed with a fluororubber O-ring.

6. A pilot-operated safety valve for hydrogen as described in claim 5, characterized in that: The piston (26) has a larger area than the valve disc (16) of the pilot valve, and an exhaust damping hole (27) is designed on the piston (26).

7. A pilot-operated safety valve for hydrogen as described in claim 6, characterized in that: The pilot valve disc (16), piston (26) and pilot valve stem (29) are an integral unit.

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