A balanced bellows safety valve for high temperature and high back pressure alternating working conditions

Abstract

A balanced bellows safety valve for high temperature and high back pressure alternating working conditions, comprising a half valve seat, a valve body, a lower adjustment ring, a positioning screw, a valve disc, a recoil disc joint, a bellows, a bellows upper joint, and a guide sleeve; wherein: after the half valve seat is connected to the valve body, the half valve seat and the inner surface of the valve body are welded; the lower adjustment ring is connected to the half valve seat by a thread, the positioning screw is connected to the valve body, and the lower adjustment ring is fixed in an appropriate position; the valve disc is connected to the recoil disc joint; one end of the bellows is welded to the recoil disc joint, and the other end is welded to the bellows upper joint; the guide sleeve is installed above the bellows upper joint, the lower end face of the guide sleeve is in full contact with the upper end face of the bellows upper joint, and the heat dissipation cavity is installed between the valve body and the valve cover. The design of the present invention enables the balanced bellows safety valve to have reliable sealing and stable performance under high temperature and high back pressure alternating working conditions.

Description

Technical Field

[0001] The invention relates to a balanced bellows safety valve used in high-temperature and high back pressure alternating working conditions, belonging to the field of safety valves. Background Art

[0002] The balanced bellows safety valve is a spring direct load safety valve that uses a bellows to minimize the effect of back pressure on the action characteristics of the safety valve. It is generally used in conditions where there is back pressure at the valve outlet and the back pressure is not greater than 50% of the set pressure. In recent years, with the development of the power industry, the demand for safety valves used in high temperature and high back pressure alternating conditions has increased. For example, in the field of solar thermal power generation, the safety valve needs to work stably at an operating temperature of 200℃ to 400℃ and a back pressure of 30% to 60% of the set pressure. The temperature and pressure are very demanding for the safety valve. At the same time, in order to avoid leakage at the valve connection caused by temperature and pressure alternation, the inlet and outlet of the safety valve are connected to the on-site pipeline by welding. When the valve is damaged, it needs to be repaired online, which greatly increases the maintenance difficulty and maintenance cost of the safety valve, which puts higher requirements on the long-term stable and reliable use of the safety valve.

[0003] Since the working conditions of this type of safety valve are extremely harsh, a conventional balanced bellows safety valve (see Figure 1 ) cannot meet the usage requirements for the following reasons:

[0004] ① Such as Figure 1 As shown, the bellows lower joint and the recoil disc of a conventional balanced bellows safety valve are generally connected by threads and flanges, and a gasket is used to seal the two. The temperature and pressure of the application conditions change, and heat tightening is not possible. Long-term application may lead to insufficient pre-tightening force of the gasket between the recoil disc and the bellows lower joint, poor sealing effect, and leakage.

[0005] ② The valve seat and valve body of a conventional balanced bellows safety valve are connected by threads, and a gasket is used to seal the two. The temperature and pressure of the operating conditions change, resulting in insufficient preload force of the gasket between the valve seat and the valve body, poor sealing effect, and leakage.

[0006] ③ Under high temperature conditions, when the valve is opened to discharge the medium, the temperature of the valve cover cavity will rise rapidly, causing the elastic modulus of the spring to change, affecting the performance of the safety valve.

[0007] ④ Common bellows upper joints such as Figure 3 As shown, the upper joint of the bellows is usually formed by hydraulic thin plate, which has low compressive strength. If the back pressure at the valve outlet is high, the upper joint of the bellows is prone to bending and deformation. Summary of the invention

[0008] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and to provide a balanced bellows safety valve for high temperature and high back pressure alternating working conditions, so that the balanced bellows safety valve has reliable sealing and stable performance under high temperature and high back pressure alternating working conditions.

[0009] The technical solution of the present invention is: a balanced bellows safety valve for high temperature and high back pressure alternating working conditions, including: a half valve seat, a valve body, a lower adjustment ring, a positioning screw, a valve disc, a recoil disc connector, a bellows, a bellows upper connector, and a guide sleeve; wherein:

[0010] After the half valve seat is connected to the valve body, the inner surface of the half valve seat and the valve body are welded; the lower adjustment ring is connected to the half valve seat through a thread, and the positioning screw is connected to the valve body; the valve disc is located at the upper end of the lower adjustment ring and is connected to the recoil disk joint; one end of the bellows is welded to the recoil disk joint, and the other end is welded to the upper joint of the bellows; the guide sleeve is installed above the upper joint of the bellows, and the heat dissipation chamber is installed between the valve body and the valve cover.

[0011] Preferably, after the half valve seat is welded to the inner surface of the valve body, grinding is performed to ensure that the roughness of the weld is not less than 3.2 μm.

[0012] Preferably, a heat sink is provided on the heat dissipation cavity to increase the heat dissipation area of ​​the cavity.

[0013] Preferably, the upper end surface of the upper joint of the bellows is designed to be a full plane, so that the lower end surface of the guide sleeve is in full contact with the upper end surface of the upper joint of the bellows.

[0014] Preferably, the upper joint of the bellows and the guide sleeve are an integral unit that bears pressure together.

[0015] Preferably, the lower adjustment ring is connected to the half valve seat by threads, and the positioning screw is connected to the valve body by threads;

[0016] The valve disc is connected to the recoil disc joint through threads;

[0017] The heat dissipation chamber is connected to the valve body and the valve cover respectively through bolts.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention adopts an integrated welding structure to weld the recoil disc and the bellows, the half valve seat and the valve body, eliminates the gasket seal, effectively avoids seal failure, reduces the risk of external leakage and maintenance costs, and improves the seal reliability;

[0020] The present invention designs a heat dissipation cavity with heat sinks to reduce the temperature of the valve cover cavity, reduce the impact on the spring, extend the life of the spring, and improve the stability of the safety valve;

[0021] The present invention enables the upper joint of the bellows to be in close contact with the guide sleeve to bear pressure together, thereby improving its pressure bearing capacity, ensuring stable operation under high back pressure, and improving overall performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a conventional balanced bellows safety valve;

[0023] Figure 2 This is a schematic diagram of the structure of a balanced bellows safety valve of the present invention;

[0024] Figure 3 This is a schematic diagram of the common bellows upper joint structure;

[0025] Figure 4 This is a schematic diagram of the structure of the upper joint of the bellows of the present invention;

[0026] Figure 5 It is a schematic diagram of the integrated structure of the bellows and the recoil disk of the present invention.

[0027] Figure symbols: 1 valve seat, 2 valve body, 3 lower adjustment ring, 4 positioning screw, 5 valve disc, 6 recoil disc joint, 7 bellows, 8 bellows upper joint, 9 guide sleeve, 10 heat dissipation cavity, 11 valve cover, 12-14 gaskets, 15 recoil disc, 16 bellows lower joint DETAILED DESCRIPTION

[0028] In order to achieve the above-mentioned purpose, the balanced bellows safety valve of the present invention mainly has the following characteristics:

[0029] 1. Design of sealing structure between bellows and recoil disk: Gasket is used to seal between bellows lower joint and recoil disk of conventional safety valve, such as Figure 1 The present invention designs an integrated structure of the bellows and the recoil disc, as shown in FIG. Figure 2 and Figure 5 As shown, the recoil disk is designed as the lower joint of the bellows and is welded to the bellows, eliminating the gasket seal. The structure is compact and the installation is convenient, which effectively solves the sealing problem between the bellows and the recoil disk under high temperature and high back pressure alternating working conditions.

[0030] 2. Sealing structure design between valve seat and valve body: The valve seat and valve body of conventional safety valves are sealed with gaskets, such as Figure 1 The present invention designs a half valve seat and valve body integrated structure, such as Figure 2 As shown, the inlet flow channel of the safety valve is divided into two parts, one part is designed on the half valve seat, and the other part is designed on the valve body. The half valve seat is welded to the valve body, eliminating the gasket seal, effectively solving the sealing problem between the valve seat and the valve body under high temperature and high back pressure alternating working conditions.

[0031] 3. Heat dissipation structure design: Conventional safety valves have no heat dissipation structure. The present invention designs a heat dissipation cavity, which is installed between the valve body and the valve cover. Figure 2 As shown, a heat sink is added to the heat dissipation cavity to increase the heat dissipation area of ​​the cavity, effectively reduce the temperature of the valve cover cavity, reduce the influence of the medium temperature on the spring performance, extend the service life of the spring, and ensure the stable performance of the safety valve.

[0032] 4. Design of the joint structure of high-pressure bellows: The joint structure of conventional bellows is as follows: Figure 3 As shown, there is a gasket between the bellows and the guide sleeve for sealing. The present invention makes full use of the guide sleeve parts, designs the upper end surface of the bellows upper joint as a full plane, eliminates the gasket between the bellows and the guide sleeve, and makes the bellows and the guide sleeve fully contact, such as Figure 4 As shown, the upper joint of the bellows and the guide sleeve can be regarded as a whole to bear pressure together, thereby improving the pressure bearing capacity of the upper joint of the bellows.

[0033] like Figure 2 As shown, the structure above the mid-flange of the valve body of the safety valve of the present invention is the same as that of the conventional safety valve, and the structure below the mid-flange of the valve body is composed of a half valve seat 1, a valve body 2, a lower adjustment ring 3, a positioning screw 4, a valve disc 5, a recoil disk joint 6, a bellows 7, a bellows upper joint 8, and a guide sleeve 9. The half valve seat 1 is connected to the valve body 2 by threads, and then the half valve seat 1 and the inner surface of the valve body 2 are welded. After welding, the roughness of the weld is ensured to be not less than 3.2μm by grinding. The lower adjustment ring 3 is connected to the half valve seat 1 by threads, and the positioning screw 4 is connected to the valve body 2 by threads, and fixes the lower adjustment ring 3 in an appropriate position; the valve disc 5 is located at the upper end of the lower adjustment ring 3 and is connected to the recoil disk joint 6 by threads, one end of the bellows 7 is welded to the recoil disk joint 6, and the other end of the bellows 7 is welded to the bellows upper joint 8, the guide sleeve 9 is installed above the bellows upper joint 8, and the lower end face of the guide sleeve 9 is completely in contact with the upper end face of the bellows upper joint 8, and the heat dissipation cavity 10 is installed between the valve body 2 and the valve cover 11, and is respectively connected to the valve body 2 and the valve cover 11 by bolts.

[0034] Through the above method, the three places with gaskets in the conventional safety valve are eliminated. Figure 1 The sealing structure of No. 11 to 13) improves the sealing reliability of the safety valve, avoids the risk of external leakage, and saves the cost of leakage repair. The heat dissipation cavity is designed to effectively reduce the temperature of the valve cover cavity and ensure the stability of the spring performance. The high back pressure bellows upper joint is designed, which is regarded as a whole with the guide sleeve to bear pressure together, which improves the pressure resistance of the bellows upper joint.

[0035] In summary, the present invention solves the problem of insufficient gasket preload and poor sealing effect caused by high temperature and high back pressure alternating working conditions of the safety valve, solves the problem of high valve cover cavity temperature affecting spring performance, and solves the problem of easy deformation of the upper joint of the bellows when the back pressure is high. It not only improves the sealing reliability and performance stability of the safety valve, but also reduces product costs and makes installation more convenient.

[0036] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

Claims

1. A balanced bellows safety valve for high temperature and high back pressure alternating working conditions, characterized by: include; Half valve seat (1), valve body (2), lower adjustment ring (3), positioning screw (4), valve disc (5), recoil disc connector (6), bellows (7), bellows upper connector (8), guide sleeve (9); wherein: After the half valve seat (1) is connected to the valve body (2), the inner surfaces of the half valve seat (1) and the valve body (2) are welded; the lower adjustment ring (3) is connected to the half valve seat (1) through a thread, and the positioning screw (4) is connected to the valve body (2); the valve disc (5) is located at the upper end of the lower adjustment ring (3) and is connected to the recoil disk joint (6); one end of the bellows (7) is welded to the recoil disk joint (6), and the other end is welded to the bellows upper joint (8); the guide sleeve (9) is installed above the bellows upper joint (8), and the heat dissipation chamber (10) is installed between the valve body (2) and the valve cover (11).

2. A balanced bellows safety valve for high temperature and high back pressure alternating working conditions according to claim 1, characterized in that: After the half valve seat (1) and the inner surface of the valve body (2) are welded, grinding is performed to ensure that the roughness of the weld is not less than 3.2 μm.

3. A balanced bellows safety valve for high temperature and high back pressure alternating working conditions according to claim 2, characterized in that: A heat sink is arranged on the heat dissipation cavity to increase the heat dissipation area of ​​the cavity.

4. A balanced bellows safety valve for high temperature and high back pressure alternating working conditions according to claim 1, characterized in that: The upper end surface of the bellows upper joint (8) is designed to be a full plane, so that the lower end surface of the guide sleeve (9) is in full contact with the upper end surface of the bellows upper joint (8).

5. A balanced bellows safety valve for high temperature and high back pressure alternating working conditions according to claim 1, characterized in that: The upper connector (8) of the bellows and the guide sleeve (9) are integrally formed to bear pressure together.

6. A balanced bellows safety valve for high temperature and high back pressure alternating working conditions according to claim 1, characterized in that: The lower adjustment ring (3) is connected to the half valve seat (1) through threads, and the positioning screw (4) is connected to the valve body (2) through threads; The valve disc (5) is connected to the recoil disc connector (6) via threads; The heat dissipation chamber (10) is connected to the valve body (2) and the valve cover (11) respectively by means of bolts.

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