A pressure regulating mechanism for a back pressure chamber of a steam safety valve and a method thereof

Abstract

The application discloses a kind of steam safety valve back pressure cavity pressure regulating mechanism and method thereof, it is related to valve technical field.The mechanism includes sequentially fixed connection's valve sleeve, valve cover and valve body;The first end of valve stem is located in valve sleeve, second end is passed through valve cover and is inserted into valve body, and second end is provided with valve flap for controlling the opening and closing of valve body inlet;Valve body inlet is communicated with the inlet of steam safety valve with back pressure cavity, valve sleeve outlet is communicated with the back pressure cavity of steam safety valve, and valve body and valve sleeve are not communicated;Valve sleeve is provided with air vent, and the first end of valve stem is rotatably connected with moving rod;The rod body of moving rod is rotatably connected with fixed rod, and the connecting place of both is used as the rotating fulcrum of moving rod, and fixed rod is fixedly connected with valve sleeve;The outer end of moving rod is provided with regulating member, which can close air vent.The application has the characteristics of reasonable design, simple structure, rapid response, continuous exhaust, long service life and easy installation and maintenance.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and in particular to a pressure regulating mechanism and method for the back pressure chamber of a steam safety valve. Background Technology

[0002] A safety valve is an automatic valve that opens and closes automatically based on the pressure of the medium. When the pressure of the medium is higher than the opening pressure of the safety valve, the safety valve opens to discharge fluid and prevent overpressure in the equipment. When the pressure inside the equipment is lower than the opening pressure of the safety valve, the safety valve automatically closes.

[0003] High-performance steam safety valves have higher requirements for discharge capacity and actuation performance compared to conventional safety valves. Therefore, their structure differs from that of conventional safety valves. The main structural changes in high-performance steam safety valves are the addition of an upper adjusting ring and a back pressure chamber. When the steam safety valve opens, the steam medium enters the back pressure chamber through the gaps between the components, creating a certain additional back pressure force. This force promotes the valve's reseating, allowing it to close quickly. However, this increased back pressure force also increases the opening resistance, slowing down the opening process and weakening the valve's rapid response. Therefore, a back pressure chamber pressure regulating mechanism is needed to adjust the magnitude of the additional back pressure force during the opening and closing process, enabling the steam safety valve to open and close rapidly. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a back pressure chamber pressure regulating mechanism and method for a steam safety valve. Specifically, when the pressure at the inlet of the regulating mechanism reaches the set pressure of the steam safety valve, the steam in the back pressure chamber can be discharged through the steam outlet (i.e., vent) of the regulating mechanism's outlet section to minimize the opening resistance of the steam safety valve. When the pressure at the inlet of the regulating mechanism is less than the set pressure of the steam safety valve, the steam outlet of the regulating mechanism's outlet section closes, increasing the additional force in the back pressure chamber, and causing the steam safety valve to close rapidly. This back pressure chamber pressure regulating mechanism has a simple structure, continuous venting, fast response speed, long service life, and can improve the operating performance of the steam safety valve, enabling rapid opening and closing of the steam safety valve.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] In a first aspect, the present invention provides a pressure regulating mechanism for the back pressure chamber of a steam safety valve, comprising a valve sleeve, a valve cover, and a valve body connected in sequence; a first end of a valve stem is located inside the valve sleeve, and a second end penetrates the valve cover and extends into the valve body, the second end being provided with a valve disc for controlling the opening and closing of the valve body inlet; the valve body inlet is connected to the inlet of a steam safety valve with a back pressure chamber, the valve sleeve outlet is connected to the back pressure chamber of the steam safety valve, and the valve body and the valve sleeve are not connected to each other;

[0007] The valve sleeve has a vent, and a movable rod is rotatably connected to the first end of the valve stem. A fixed rod is rotatably connected to the body of the movable rod, and the connection point between the two serves as the rotation fulcrum of the movable rod. The fixed rod is fixedly connected to the valve sleeve. An adjusting element that can close the vent is provided at the outer end of the movable rod. By axially moving the valve stem under air pressure, the movable rod can be driven to rotate up and down around the rotation fulcrum, thereby opening and closing the vent.

[0008] Preferably, a spring that provides axial preload is fitted outside the valve stem located inside the valve cover.

[0009] Preferably, a heat insulation plate is also provided between the valve sleeve and the valve cover.

[0010] Preferably, the adjusting member is a hemispherical structure with its arc surface facing the vent.

[0011] Preferably, the valve sleeve, valve cover, and valve body are not interconnected, and the connection between the valve stem and the valve cover and valve body is sealed.

[0012] Preferably, the valve sleeve includes a vertical section and a horizontal section; the bottom end of the vertical section is connected to the top of the valve cover for housing the valve stem; one end of the horizontal section is connected to the vertical section, and the other end is connected to the back pressure chamber of the steam safety valve, with a vent at the top of the horizontal section; one end of the moving rod is rotatably connected to the first end of the valve stem, and the other end is located within the horizontal section; the fixed rod is located within the horizontal section and is arranged perpendicularly to the moving rod.

[0013] Preferably, a groove is provided at the center of the first end of the valve stem, and threaded holes are provided at both ends of the groove. The double-ended stud rotatably connects the moving rod to the valve stem through the threaded holes.

[0014] Preferably, the pivot point is located on the side of the moving rod closer to the valve stem.

[0015] Preferably, the valve body opening pressure is adjusted to the set pressure of the steam safety valve by adjusting the spring preload, the weight of the valve stem and the valve disc.

[0016] Secondly, the present invention provides a method for regulating the back pressure chamber pressure using the back pressure chamber pressure regulating mechanism of any of the steam safety valves described in the first aspect, as follows:

[0017] When the inlet pressure of the valve body reaches the set pressure of the steam safety valve, the valve stem moves upward and drives the moving rod to rotate clockwise around the pivot point. The adjusting element leaves the vent, and the steam in the back pressure chamber is discharged through the vent, thereby reducing the opening resistance of the steam safety valve.

[0018] When the inlet pressure of the valve body is slightly less than the set pressure of the steam safety valve, the valve stem moves down and drives the moving rod to rotate counterclockwise around the pivot point. The adjusting element contacts the vent, the pressure in the back pressure chamber rises, and the steam safety valve closes faster.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The back pressure chamber pressure regulating mechanism reduces the resistance during the opening process of the steam safety valve by controlling the opening or closing of the vent, and has virtually no impact on the beneficial effect of the back pressure chamber on the closing process of the steam safety valve, thereby enabling rapid opening and closing of the steam safety valve. This back pressure chamber pressure regulating mechanism features fast response, long service life, continuous venting, simple structure, and easy maintenance, significantly improving the operating performance of the steam safety valve and making it suitable for more stringent operating conditions. Attached Figure Description

[0021] Figure 1 This is a half-sectional view of the back pressure chamber pressure regulating mechanism involved in this invention.

[0022] Figure 2 This is a half-sectional view of the valve stem of the back pressure chamber pressure regulating mechanism involved in this invention.

[0023] Figure 3 This is a diagram showing the pressure change in the back pressure chamber involved in this invention, wherein stage 1 is the steam safety valve opening stage; stage 2 is the steam safety valve stable discharge stage; and stage 3 is the steam safety valve closing stage.

[0024] In the diagram: 1. Valve body; 2. Valve stem; 3. Valve disc; 4. Spring; 5. Valve cover; 6. Heat insulation plate; 7. Moving rod; 8. Fixed rod; 9. Valve sleeve; 10. Vent. Detailed Implementation

[0025] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0026] Without a back pressure chamber pressure regulating mechanism, when the inlet pressure of the steam safety valve reaches its set pressure, some steam enters the back pressure chamber through the gaps between the components. At this time, the pressure change in the back pressure chamber is as follows: Figure 3 As shown in Stage 1, the pressure inside the back pressure chamber increases rapidly, which hinders the opening of the steam safety valve, increases its opening resistance, and slows down its opening speed. To address this drawback, this invention designs a pressure regulating mechanism, such as... Figure 1As shown, the pressure regulating mechanism mainly includes a valve body 1, a valve stem 2, a valve disc 3, a spring 4, a valve cover 5, and a valve sleeve 9. The valve sleeve 9, valve cover 5, and valve body 1 are fixedly connected from top to bottom. The valve stem 2 includes a first end and a second end. The first end is located inside the valve sleeve 9, and the second end passes through the valve cover 5 and extends into the valve body 1. The second end is equipped with a valve disc 3, which is used to control the opening and closing of the valve body 1 inlet.

[0027] In this invention, the inlet of the pressure regulating mechanism is connected to the inlet of the steam safety valve with a back pressure chamber. This is mainly so that the opening or closing of the back pressure chamber pressure regulating mechanism can be determined by the inlet pressure of the steam safety valve, thereby regulating the steam pressure in the back pressure chamber. The outlet is connected to the opening on the back pressure chamber of the steam safety valve. The opening pressure of the back pressure chamber pressure regulating mechanism is the same as the set pressure of the steam safety valve. To achieve this goal, the spring 4 of the regulating mechanism needs to be selected appropriately, and the weight of the valve stem 2 and valve disc 3 needs to be set appropriately so that the opening pressure of the regulating mechanism is the set pressure of the steam safety valve. That is to say, the gas in the valve body 1 can communicate with the inlet of the steam safety valve, and the gas in the valve sleeve 9 can communicate with the atmosphere (when the vent 10 is open) or with the back pressure chamber of the steam safety valve (when the vent 10 is closed).

[0028] In this embodiment, a spring 4 that provides axial preload is sleeved on the outside of the valve stem 2 located inside the valve cover 5, and a heat insulation plate 6 is also provided between the valve sleeve 9 and the valve cover 5. The valve sleeve 9, the valve cover 5 and the valve body 1 are not in communication with each other, and the connection between the valve stem 2 and the valve cover 5 and the valve body 1 is sealed.

[0029] In the pressure regulating mechanism, a vent 10 is provided on the valve sleeve 9, and a moving rod 7 is rotatably connected to the first end of the valve stem 2. A fixed rod 8 is rotatably connected to the body of the moving rod 7, and the connection between the moving rod and the fixed rod serves as the rotation fulcrum of the moving rod 7. The fixed rod 8 is fixedly connected to the valve sleeve 9. In this embodiment, in order to achieve a small displacement of the valve stem (2) to drive the right end of the moving rod (7) to rotate a larger angle, the rotation fulcrum can be located on the side of the moving rod 7 closer to the valve stem 2, that is, the rotation fulcrum is set on the left side of the moving rod.

[0030] In this embodiment, as Figure 2 As shown, the valve stem 2 and the moving rod 7 can be connected in this way. That is, a groove is opened at the center of the first end of the valve stem 2, and the two sides are flattened. Threaded holes are provided at both ends of the groove. The moving rod 7 is rotatably connected to the valve stem 2 through the threaded holes. In order to protect the flat surfaces on both sides of the upper end of the valve stem (2), a shim is required when installing the double-ended stud. The length of the double-ended stud is equal to or slightly smaller than the diameter of the valve stem. When the valve stem (2) moves to the maximum displacement, the moving rod (7) just contacts the lower end of the outlet section without collision.

[0031] In the pressure regulating mechanism, the outer end of the moving rod 7 is provided with an adjusting component that can close the vent 10. By the axial movement of the valve rod 2 under the action of air pressure, the moving rod 7 can be driven to rotate up and down around the pivot point, thereby realizing the opening and closing of the vent 10.

[0032] In this embodiment, the adjusting component is a hemispherical structure with its arc surface facing the vent 10. This allows for a large-scale blockage of the vent 10 through the arc surface. Of course, the adjusting component does not need to achieve a completely sealed closure with the vent; a certain gap can be left, which will not affect the adjustment of the back pressure chamber pressure. This further reduces the manufacturing difficulty of this device. When the pressure regulating mechanism is closed, the spherical part of the moving rod 7 contacts the vent at the upper part of the outlet section of the regulating mechanism, leaving a certain gap between them. After the steam safety valve with the back pressure chamber opens and closes, the remaining gas in the back pressure chamber can be discharged through the gap.

[0033] In this embodiment, the valve sleeve 9 mainly includes a vertical section and a horizontal section. The bottom end of the vertical section is connected to the top of the valve cover 5 and is used to fit the valve stem 2 inside. One end of the horizontal section is connected to the vertical section, and the other end is connected to the back pressure chamber of the steam safety valve. A vent 10 is opened at the top of the horizontal section. One end of the moving rod 7 is rotatably connected to the first end of the valve stem 2, and the other end is located in the horizontal section. The fixed rod 8 is located in the horizontal section and is arranged perpendicular to the moving rod 7.

[0034] The method for regulating the back pressure chamber pressure of the aforementioned steam safety valve back pressure chamber pressure regulating mechanism is as follows:

[0035] 1) When the inlet pressure of valve body 1 reaches the set pressure of steam safety valve, valve stem 2 moves upward and drives moving rod 7 to rotate clockwise around the pivot point. Adjusting component moves away from vent port 10, and steam in back pressure chamber is discharged through vent port 10, reducing the opening resistance of steam safety valve.

[0036] 2) When the inlet pressure of valve body 1 is slightly less than the set pressure of steam safety valve, valve stem 2 moves down and drives moving rod 7 to rotate counterclockwise around the pivot point. The adjusting element contacts the vent 10, and the pressure in the back pressure chamber rises, which can speed up the closing of steam safety valve.

[0037] During this process, because the outlet section of the regulating mechanism is connected to the opening on the back pressure chamber, the steam in the back pressure chamber can be discharged through the steam outlet on the outlet section of the pressure regulating mechanism, and the pressure in the back pressure chamber decreases rapidly, as shown in the following pressure change. Figure 3 As shown in Stage 1, the pressure regulating mechanism effectively reduces the pressure in the back pressure chamber of the steam safety valve when it opens, thereby significantly increasing the opening speed of the safety valve and making it suitable for more stringent operating conditions. When the steam safety valve is discharging steadily, the pressure in its back pressure chamber remains stable regardless of whether a pressure regulating mechanism is present, and does not affect the normal operation of the steam safety valve. Figure 3As shown in Stage 2. Without a pressure regulating mechanism, when the inlet pressure of the steam safety valve is lower than its opening pressure, the steam safety valve begins to close. At this time, the pressure in the back pressure chamber increases, which helps the steam safety valve to quickly reseat. Figure 3 As shown in stage 3. When a pressure regulating mechanism is present, if the inlet pressure of the steam safety valve is less than its opening pressure, the pressure regulating mechanism closes. The valve stem 2 of the regulating mechanism moves downward, and the moving rod 7 rotates counterclockwise around the fixed rod inside the outlet section of the pressure regulating mechanism. The hemispherical part contacts the vent, the vent hole closes, the back pressure chamber pressure increases, accelerating the reseating process of the steam safety valve. The pressure change is as follows: Figure 3 As shown in Stage 3, the pressure regulating mechanism has virtually no impact on the reseating process of the steam safety valve. After the steam safety valve closes, a certain amount of gas remains in the back pressure chamber and needs to be released to avoid affecting the next opening. Therefore, when the moving rod contacts the vent, there is a certain gap between them, allowing some gas in the back pressure chamber to be released through this gap to reduce the pressure in the back pressure chamber and not affect the next rapid opening of the steam safety valve.

[0038] This invention is reasonably designed and features a simple structure, rapid response, continuous exhaust, long service life, and easy installation and maintenance.

[0039] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A pressure regulating mechanism for the back pressure chamber of a steam safety valve, characterized in that, It includes a valve sleeve (9), a valve cover (5), and a valve body (1) that are fixedly connected in sequence; the first end of the valve stem (2) is located inside the valve sleeve (9), and the second end passes through the valve cover (5) and extends into the valve body (1). The second end is provided with a valve disc (3) for controlling the opening and closing of the valve body (1) inlet; the inlet of the valve body (1) is connected to the inlet of the steam safety valve with a back pressure chamber, the outlet of the valve sleeve (9) is connected to the back pressure chamber of the steam safety valve, and the valve body (1) and the valve sleeve (9) are not connected to each other; The first end of the valve stem (2) is rotatably connected to a movable rod (7); the valve sleeve (9) includes a vertical section and a horizontal section; the bottom end of the vertical section is connected to the top of the valve cover (5) for fitting the valve stem (2) inside; one end of the horizontal section is connected to the vertical section, and the other end is connected to the back pressure chamber of the steam safety valve, and a vent (10) is opened at the top of the horizontal section; one end of the movable rod (7) is rotatably connected to the first end of the valve stem (2), and the other end is located in the horizontal section; the fixed rod (8) is located in the horizontal section and is arranged perpendicular to the movable rod (7); A fixed rod (8) is rotatably connected to the body of the movable rod (7), and the connection point of the two serves as the rotation fulcrum of the movable rod (7). The fixed rod (8) is fixedly connected to the valve sleeve (9). The outer end of the movable rod (7) is provided with an adjusting component that can close the vent (10). By the axial movement of the valve rod (2) under air pressure, the movable rod (7) can be driven to rotate up and down around the rotation fulcrum, thereby realizing the opening and closing of the vent (10).

2. The steam safety valve back pressure chamber pressure regulating mechanism according to claim 1, characterized in that, A spring (4) that can provide axial preload is sleeved outside the valve stem (2) located inside the valve cover (5).

3. The steam safety valve back pressure chamber pressure regulating mechanism according to claim 1, characterized in that, A heat insulation plate (6) is also provided between the valve sleeve (9) and the valve cover (5).

4. The steam safety valve back pressure chamber pressure regulating mechanism according to claim 1, characterized in that, The adjusting component is a hemispherical structure with its arc surface facing the vent (10).

5. The steam safety valve back pressure chamber pressure regulating mechanism according to claim 1, characterized in that, The valve sleeve (9), valve cover (5) and valve body (1) are not connected to each other, and the connection between the valve stem (2) and the valve cover (5) and valve body (1) is sealed.

6. The steam safety valve back pressure chamber pressure regulating mechanism according to claim 1, characterized in that, The valve stem (2) has a groove at the center of the first end, and threaded holes at both ends of the groove. The double-ended stud connects the moving rod (7) to the valve stem (2) through the threaded holes.

7. The steam safety valve back pressure chamber pressure regulating mechanism according to claim 1, characterized in that, The pivot point is located on the side of the moving rod (7) near the valve stem (2).

8. The steam safety valve back pressure chamber pressure regulating mechanism according to claim 2, characterized in that, By adjusting the preload of the spring (4) and the weight of the valve stem (2) and valve disc (3), the opening pressure of the valve body (1) is made to be the set pressure of the steam safety valve.

9. A method for regulating the back pressure chamber pressure of a steam safety valve according to any one of claims 1 to 8, characterized in that, Specifically as follows: When the inlet pressure of the valve body (1) reaches the set pressure of the steam safety valve, the valve stem (2) moves upward and drives the moving rod (7) to rotate clockwise around the pivot point. The adjusting element leaves the vent (10), and the steam in the back pressure chamber is discharged through the vent (10), thereby reducing the opening resistance of the steam safety valve. When the inlet pressure of the valve body (1) is slightly less than the set pressure of the steam safety valve, the valve stem (2) moves down and drives the moving rod (7) to rotate counterclockwise around the pivot point. The adjusting element contacts the vent (10), the pressure in the back pressure chamber rises, and the steam safety valve closes faster.

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