Force transfer structure for improving action stability of high-pressure safety valve and safety valve

Abstract

The invention discloses a force transmission structure for improving action stability of a high-pressure safety valve and the safety valve, and relates to the field of safety valve structures.The force transmission structure comprises a recoil disc, a valve clack, a guide sleeve and a steel ball, the guide sleeve is provided with a limiting through hole, one end of the recoil disc is installed in the limiting through hole, and the recoil disc and the guide sleeve are in sliding connection in the axis direction of the limiting through hole; a first mounting groove is formed in the other end of the recoil disc, the valve clack is mounted in the first mounting groove, a second mounting groove is formed in the middle of the end face, facing the bottom of the first mounting groove, of the valve clack, and the steel ball is mounted between the recoil disc and the valve clack and makes contact with the bottom of the first mounting groove and the bottom of the second mounting groove. The setting stability of the safety valve under the high-pressure working condition is guaranteed, the setting pressure deviation is smaller than or equal to 3%, and the setting pressure stability deviation is within + / -1%.

Description

Technical Field

[0001] The patent of this invention belongs to the technical field of safety valve structure design, and specifically relates to a force transmission structure and a safety valve for improving the operating stability of a high-pressure safety valve, which improves the operating stability of the safety valve under high-pressure conditions. Background Art

[0002] Safety valves are important overpressure protection devices for pressure vessels and process systems. When the equipment reaches the set pressure of the safety valve, the safety valve automatically opens to discharge a rated amount of fluid, thereby reducing the equipment pressure and ensuring the safety of the equipment.

[0003] The stable operation of the safety valve is an important guarantee for the smooth operation of the protection equipment. According to the standard ASME XIII "Rules For Overpressure Protection" and the national standard GB / T 12243 "Spring Loaded Safety Valve", the requirements for the stability of the safety valve operation are as follows:

[0004] Table 1. Safety valve action stability requirements

[0005]

[0006] Common safety valve structures such as Figure 1 As shown, the spring direct load safety valve is provided with preload by spring 1, and the preload is transmitted step by step through valve stem 2, recoil disc 3 and valve disc 4, and finally forms pressure on the contact surface between valve disc 4 and valve seat 5, which is the set pressure.

[0007] When the system pressure is lower than the set pressure of the safety valve, the valve disc 4 is pressed against the valve seat 5, and the safety valve is in a closed state and remains sealed. When the system pressure is higher than the set pressure, the system pressure acting on the valve disc 4 overcomes the spring preload force to open the safety valve. When the system pressure drops below the return pressure, the safety valve closes again.

[0008] like Figure 2 As shown in FIG. 1 , a common safety valve force transmission structure is composed of a valve stem 2, a recoil disc 3 and a valve flap 4. The acting point between the valve stem 2 and the recoil disc 3 is a, and the acting point between the recoil disc 3 and the valve flap 4 is b.

[0009] Due to the influence of factors such as parts processing accuracy, parts matching tolerance, assembly deviation, etc., the spring preload force cannot ensure vertical transmission, and the recoil disk 3 and the valve disc 4 will bear a part of the lateral force.

[0010] The magnitude of the lateral force will directly affect the stability of the safety valve, resulting in uneven pressure between the valve disc 4 and the valve seat 5, causing the safety valve to leak and open prematurely, that is, the setting deviation becomes larger. In addition, the lateral force will increase the friction between the recoil disc 3 and the guide sleeve 6, resulting in unstable safety valve action.

[0011] The above problem will increase with the increase of the set pressure of the safety valve and the increase of the spring preload, and the lateral force of the spring will also increase accordingly, which will have a more obvious impact on the stability of the set pressure, causing the action stability to exceed the standard requirements. Summary of the invention

[0012] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and provide a force transmission structure with a steel ball for improving the stability of the operation of a high-pressure safety valve, so that the safety valve can meet the requirements of standard specifications under high pressure, such as the safety valve set pressure deviation, the safety valve set pressure stability deviation and mechanical properties, thereby achieving stable and reliable online operation performance of the safety valve.

[0013] The technical solutions provided by this application are as follows:

[0014] A force transmission structure for improving the operation stability of a high-pressure safety valve comprises a recoil disc, a valve disc, a guide sleeve and a steel ball. The guide sleeve is provided with a limit through hole. One end of the recoil disc is installed in the limit through hole. The recoil disc and the guide sleeve are slidably connected along the axial direction of the limit through hole. A first mounting groove is provided at the other end of the recoil disc. The valve disc is installed in the first mounting groove. A second mounting groove is provided in the middle of the end surface of the valve disc facing the bottom of the first mounting groove. The steel ball is installed between the recoil disc and the valve disc. The steel ball contacts the bottom of the first mounting groove and the bottom of the second mounting groove.

[0015] The first mounting groove includes a cylindrical groove and a conical groove located at the bottom of the cylindrical groove; the second mounting groove is conical in shape.

[0016] The cone angles of the tapered groove and the second mounting groove are both 120°.

[0017] There is a clearance fit between the outer circumferential surface of the valve disc and the recoil disk.

[0018] The difference between the valve flap diameter and the cylindrical groove diameter is between 0.05 and 0.1.

[0019] The distance between the contact point between the steel ball and the valve disc and the contact surface between the valve disc and the valve seat / the outer diameter of the valve disc=0.3-0.5.

[0020] When the valve flap is coaxial with the first mounting groove, the steel ball contacts the bottom of the first mounting groove and the bottom of the second mounting groove, and the center of the steel ball is coaxial with the first mounting groove and the second mounting groove, the valve flap does not contact the inner wall of the first mounting groove.

[0021] A safety valve, comprising a valve body, a valve seat, a valve stem, a spring and any one of the above force transmission structures for improving the stability of the high-pressure safety valve, wherein a valve cavity is arranged in the valve body, the valve body has a first outlet, a second outlet and a third outlet connected to the valve cavity, the first outlet of the valve body is connected to the valve seat, the second outlet is directly opposite to the first outlet, the second outlet of the valve body is connected to the valve cover, the valve stem is slidably connected to the valve cover, and the spring is arranged outside the valve stem for driving the valve cover to move;

[0022] The force transmission structure includes a recoil disc, a valve disc, a guide sleeve and a steel ball. The guide sleeve is clamped between the first outlet end of the valve body and the valve cover. The end of the valve stem is installed in the limiting through hole and contacts with the end of the recoil disc. The valve disc is opposite to the valve seat.

[0023] When the valve flap contacts the valve seat, the length of the recoil disc inserted into the guide sleeve is 0.2 to 0.4 times the diameter of the guide sleeve. Through this arrangement, the center of gravity of the recoil disc is further reduced.

[0024] In summary, this application at least includes the following beneficial technical effects:

[0025] The use of a new steel ball force transmission structure ensures the setting stability of the safety valve under high-pressure conditions, achieving a set pressure deviation of ≤3% and a set pressure stability deviation within ±1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Common safety valve structure diagram;

[0027] Figure 2 Common safety valve force transmission structure diagram;

[0028] Figure 3 Improved safety valve force transmission structure diagram.

[0029] Explanation of the accompanying figures: 1. Spring; 2. Valve stem; 3. Recoil disc; 4. Valve disc; 5. Valve seat; 6. Guide sleeve; 7. Steel ball. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] The present application discloses a force transmission structure for improving the operating stability of a high-pressure safety valve, such as Figure 3 As shown, it includes a spring 1, a valve stem 2, a recoil disc 3, a valve disc 4, a guide sleeve 6 and a steel ball 7.

[0032] The guide sleeve 6 is provided with a limited through hole, one end of the recoil disc 3 is installed in the limited through hole, the recoil disc 3 and the guide sleeve 6 are slidably connected along the axial direction of the limited through hole, the other end of the recoil disc 3 is provided with a first mounting groove, the valve disc 4 is installed in the first mounting groove, the first mounting groove includes a cylindrical groove and a conical groove located at the bottom of the cylindrical groove, the valve disc 4 is provided with a second mounting groove in the middle of the end surface facing the bottom of the first mounting groove, the second mounting groove is conical, and the cone angles of the conical groove and the second mounting groove are both 120°, the steel ball 7 is installed between the recoil disc 3 and the valve disc 4, the steel ball 7 contacts the bottom of the conical groove and the second mounting groove, forming two line contacts. The end of the second mounting groove to the edge of the valve disc 4 is an annular surface, and the width of the annular surface is 2 to 4 mm.

[0033] There is a clearance fit between the outer circumferential surface of the valve disc 4 and the recoil disc 3, that is, the valve disc 4 swings in the recoil disc 3 with the contact point between the valve disc 4 and the steel ball 7 as the center. The swing amplitude determines the stability and sealing of the safety valve. By designing different swing amounts for testing, it is finally determined that the swing angle of the valve disc is most suitable between 0.55 and 0.85°, which also determines that the clearance between the outer circumferential surface of the valve disc 4 and the recoil disc 3 is 0.2 to 0.335 mm. The diameter of the steel ball 7 is determined by the ratio of the distance between the contact point of the steel ball 7 and the valve disc 4 and the contact surface of the valve disc 4 and the valve seat 5 to the outer diameter of the valve disc 4.

[0034] When the valve disc 4 contacts the valve seat 5 , the end of the recoil disc 3 inserted into the guide sleeve 6 is the force point position A, and the distance between the force point position A and the end of the limit through hole toward the valve seat 5 is 5 to 10 mm.

[0035] By adding a steel ball 7 between the recoil disc 3 and the valve disc 4, the self-aligning ability of the valve disc 4 is enhanced through the characteristic that the position of the steel ball 7 can be changed. At the same time, the force point position A of the valve stem 2 and the recoil disc 3 is lowered, so that the influence of the lateral force on the recoil disc 3 and the valve disc 4 is reduced, thereby ensuring the operating stability of the safety valve.

[0036] The force transmission structure of this patent has a double force transmission point design of the steel ball: a double force transmission point design of line contact of the steel ball 7 is adopted between the recoil disk 3 and the valve disc 4, the first force transmission point is located between the steel ball 7 and the recoil disk 3, and the second force transmission point is located between the steel ball 7 and the valve disc 4, both of which are line contacts.

[0037] During the setting, opening, discharging and reseating process of the safety valve, the lateral force acting on the recoil disc 3 will pass through the steel ball 7 when it is transmitted to the valve disc 4. The position of the steel ball 7 itself can be slightly changed, which enhances the self-aligning ability of the valve disc 4 and reduces the influence of the lateral force.

[0038] ② Design of the relationship between the valve disc force point and the center of gravity: Figure 3As shown, according to the calculation formula of the annular disk in the "Mechanical Design Manual", the thickness of the valve disc under different pressure levels is calculated, the thickness of the valve disc 4 is reduced while ensuring the strength, and a steel ball 7 of appropriate size is added between the recoil disk 3 and the valve disc 4. The force points of the valve disc 4 and the steel ball 7 are determined according to the ratio of the distance from the contact point of the steel ball 7 and the valve disc 4 to the valve disc 4 and the valve seat 5 to the outer diameter of the valve disc 4. The ratio needs to be less than 0.5, and the distance between the force point of the valve disc 4 and the center of gravity of the valve disc 4 is kept within 4.5 mm, thereby increasing the stability of force conduction.

[0039] ③ Design of the force bearing point of the recoil plate: Figure 3 As shown, the force point position A between the valve stem 2 and the recoil disk 3 is adjusted, and moved down by an appropriate distance Y to lower the force transmission point and reduce the influence of the lateral force on the recoil disk 3.

[0040] A safety valve comprises a valve body, a valve seat 5, a valve stem 2, a spring 1 and the above-mentioned force transmission structure, wherein a valve cavity is arranged in the valve body, the valve body has a first outlet, a second outlet and a third outlet connected to the valve cavity, the first outlet of the valve body is connected to the valve seat 5, the second outlet is directly opposite to the first outlet, the second outlet of the valve body is connected to the valve cover, the valve stem 2 is slidably connected to the valve cover, and the spring 1 is arranged outside the valve stem 2 for driving the valve cover to move. The force transmission structure comprises a recoil disc 3, a valve flap 4, a guide sleeve 6 and a steel ball 7, the guide sleeve 6 is clamped between the first outlet end of the valve body and the valve cover, the end of the valve stem 2 is installed in the limit through hole and contacts with the end of the recoil disc 3, and the valve flap 4 is directly opposite to the valve seat 5.

[0041] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0042] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A force transmission structure for improving the operating stability of a high-pressure safety valve, characterized in that: The invention comprises a recoil disc (3), a valve flap (4), a guide sleeve (6) and a steel ball (7); the guide sleeve (6) is provided with a limit through hole; one end of the recoil disc (3) is mounted in the limit through hole; the recoil disc (3) and the guide sleeve (6) are slidably connected along the axial direction of the limit through hole; the other end of the recoil disc (3) is provided with a first mounting groove; the valve flap (4) is mounted in the first mounting groove; a second mounting groove is provided in the middle of the end surface of the valve flap (4) facing the bottom of the first mounting groove; the steel ball (7) is mounted between the recoil disc (3) and the valve flap (4); the steel ball (7) contacts the bottom of the first mounting groove and the bottom of the second mounting groove.

2. A force transmission structure for improving the operating stability of a high-pressure safety valve according to claim 1, characterized in that: The first mounting groove includes a cylindrical groove and a conical groove located at the bottom of the cylindrical groove; the second mounting groove is conical in shape.

3. A force transmission structure for improving the operating stability of a high-pressure safety valve according to claim 2, characterized in that: The cone angles of the tapered groove and the second mounting groove are both 120°.

4. A force transmission structure for improving the operating stability of a high-pressure safety valve according to claim 2, characterized in that: There is a clearance fit between the outer circumferential surface of the valve flap (4) and the recoil disc (3).

5. A force transmission structure for improving the operating stability of a high-pressure safety valve according to claim 4, characterized in that: The difference between the diameter of the valve flap (4) and the diameter of the cylindrical groove is between 0.05 and 0.

1.

6. A force transmission structure for improving the operating stability of a high-pressure safety valve according to claim 1, characterized in that: The distance between the contact point between the steel ball (7) and the valve flap (4) and the contact surface between the valve flap (4) and the valve seat (5) / the outer diameter of the valve flap (4) = 0.3-0.

5.

7. A force transmission structure for improving the operating stability of a high-pressure safety valve according to claim 1, characterized in that: When the valve flap (4) is coaxial with the first mounting groove, the steel ball (7) contacts the bottom of the first mounting groove and the bottom of the second mounting groove, and the center of the steel ball (7) is coaxial with the first mounting groove and the second mounting groove, the valve flap (4) does not contact the inner wall of the first mounting groove.

8. A safety valve, characterized in that: The invention comprises a valve body, a valve seat (5), a valve stem (2), a spring (1) and a force transmission structure for improving the operating stability of a high-pressure safety valve as described in any one of claims 1 to 7, wherein a valve cavity is arranged in the valve body, the valve body has a first outlet, a second outlet and a third outlet connected to the valve cavity, the first outlet position of the valve body is connected to the valve seat (5), the second outlet is directly opposite to the first outlet, the second outlet position of the valve body is connected to the valve cover, the valve stem (2) is slidably connected to the valve cover, the spring (1) is arranged outside the valve stem (2) and is used to drive the valve cover to move; the force transmission structure comprises a recoil disk (3), a valve flap (4), a guide sleeve (6) and a steel ball (7), the guide sleeve (6) is clamped between the first outlet end of the valve body and the valve cover, the end of the valve stem (2) is installed in the limiting through hole and contacts with the end of the recoil disk (3), and the valve flap (4) is directly opposite to the valve seat (5).

9. The safety valve according to claim 9, characterized in that: When the valve flap (4) contacts the valve seat (5), the length of the recoil disc (3) inserted into the guide sleeve (6) is 0.2 to 0.4 times the aperture of the guide sleeve (6).

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