An adjustable labyrinth type minimum flow control valve

Abstract

The present invention relates to an adjustable labyrinth minimum flow control valve, comprising a valve body, a valve cover, a valve core, a valve seat, a valve stem and an actuator, wherein the valve seat and the valve core are arranged in the valve body, one end of the valve stem extends into the valve body and is connected to the valve core, and the other end extends out of the valve cover and is connected to the actuator, and the control valve also comprises a labyrinth disc assembly, wherein the labyrinth disc assembly is fixedly arranged in the valve body, the labyrinth disc assembly is sleeved on the circumference of the valve core, and the labyrinth disc assembly comprises a plurality of hollow labyrinth discs and a plurality of solid labyrinth discs. Compared with the prior art, the present invention effectively prevents the valve core from being exposed due to the selection margin, converts the margin stroke into an empty stroke, prevents the minimum flow control valve from leaking or being damaged under long-term flushing under high-pressure medium and two-phase flow conditions, and effectively improves the reliability and durability of the present invention.

Description

Technical Field

[0001] The invention relates to a minimum flow control valve, in particular to an adjustable labyrinth type minimum flow control valve. Background Art

[0002] The minimum flow circulation valve is a key equipment for the boiler feed pump of a power plant. It is an important equipment to ensure the safe operation of the unit. When the feed water flow is less than a certain value, the minimum flow valve of the feed pump opens quickly to bypass part of the feed water to the feed pump inlet tank, ensuring a certain flow at the feed pump outlet to prevent the feed pump from vaporizing; when the feed pump outlet flow reaches a certain value, the valve will gradually close to improve the economy of the feed pump operation. Because this valve is used in extremely harsh environments, the valve will be damaged by severe cavitation and scouring, and will also generate a lot of noise and vibration, which has long been a problem that has troubled valve experts around the world.

[0003] According to the selection regulations of the regulating valve, the minimum flow diameter inside the regulating valve and the medium flow rate when passing through the valve core ensure that the valve core has sufficient flow area; for two-phase flow conditions, the valve core outlet flow rate must be less than 22.5m / s. When designers select the minimum flow valve for the pump according to the parameter requirements of the working conditions, they must calculate based on the flow rate control requirements of the two-phase flow. The flow rate requirements must be strictly controlled during selection to avoid vibration, cavitation and other problems caused by high flow rates. The most appropriate selection of the minimum flow regulating valve is that the corresponding valve opening under the maximum flow condition should be greater than 85%.

[0004] However, the following situation often occurs: the valve opening of the selected minimum flow valve for the pump is only 50% according to the maximum flow value (i.e., flow demand) in each operating condition required by the unit. The valve capacity of the valve has a margin of 50%. If a smaller valve core is selected, the valve opening can be increased, but the flow rate will exceed the flow rate control requirements of the two-phase flow, which will cause greater harm. Moreover, after the overspeed exceeds the flow rate range of the selection software, the designer cannot select the valve. Therefore, the final result is that there is no way to select a smaller valve, and only a minimum flow valve for the pump with a larger specification than the actual demand can be selected. That is to say, the actual opening of the valve is 50% to meet the water flow rate required by the unit. In this case, by adjusting the actuator, it can be achieved that the actuator displays an opening of 0-100% while the corresponding actual valve mechanical opening is only 0-50%, which meets the operating requirements of the unit. Although the valve specification is one level larger, it does not affect the use requirements; however, the actual long-term opening of the valve can only be 50%, which means that half of the valve core of the valve will be exposed to the environment, and the differential pressure before and after the minimum flow valve is extremely large. Long-term scouring under high-pressure medium and two-phase flow conditions will eventually cause obvious leakage or damage to the minimum flow valve of the pump, affecting the service life of the valve and the thermal economy of the unit. Summary of the invention

[0005] The purpose of the present invention is to provide an adjustable labyrinth type minimum flow control valve in order to overcome the defects of the prior art.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] An adjustable labyrinth type minimum flow control valve comprises a valve body, a valve cover, a valve core, a valve seat, a valve stem and an actuator, wherein the valve seat and valve core are arranged in the valve body, one end of the valve stem extends into the valve body and is connected to the valve core, and the other end extends out of the valve cover and is connected to the actuator, the control valve also comprises a labyrinth disc assembly, the labyrinth disc assembly is fixedly arranged in the valve body, the labyrinth disc assembly is sleeved on the peripheral side of the valve core, and the labyrinth disc assembly comprises a plurality of hollow labyrinth discs and a plurality of solid labyrinth discs.

[0008] Preferably, the solid labyrinth disc is an annular disc, a plurality of labyrinth flow channels are arranged on the annular disc, and a flow blocking member is arranged in the labyrinth flow channel of the solid labyrinth disc, and the flow blocking member completely blocks the labyrinth flow channel on the solid labyrinth disc.

[0009] Preferably, the hollow labyrinth disc is an annular disc, and a plurality of labyrinth flow channels are provided on the annular disc.

[0010] Preferably, the outlet of the labyrinth flow channel includes at least one parallel outlet flow channel.

[0011] Preferably, the middle portion of the labyrinth flow channel includes a plurality of bends.

[0012] Preferably, the annular disc is provided with 8 labyrinth flow channels.

[0013] Preferably, a packing chamber is formed between the valve stem and the valve cover, and packing and packing gaskets are arranged in the packing chamber.

[0014] Preferably, a valve core sealing ring is provided on the periphery of the valve core.

[0015] Preferably, a valve cover flange, valve cover bolts and valve cover nuts are provided on the circumferential side of the valve cover, and the valve cover and valve body are fixedly connected by the valve cover flange, valve cover bolts and valve cover nuts.

[0016] Preferably, the number of hollow labyrinth discs and solid labyrinth discs in the labyrinth disc assembly is the same. When the present invention is used, the number of hollow labyrinth discs and solid labyrinth discs can be adjusted according to the valve opening and the corresponding flow requirements to achieve the adjustment of the actual valve opening.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The labyrinth disc assembly of the present invention uses a solid labyrinth disc and a hollow labyrinth disc to cooperate, effectively preventing the valve core from being exposed due to the selection margin, turning the margin stroke into an empty stroke, and preventing the minimum flow control valve from leaking or being damaged under long-term flushing under high-pressure medium and two-phase flow conditions, thereby effectively improving the reliability and durability of the present invention;

[0019] (2) The number and ratio of the solid labyrinth discs and the hollow labyrinth discs of the present invention can be adjusted according to actual work requirements, thereby effectively improving the scope of application of the present invention and improving its universality;

[0020] (3) The solid labyrinth disc of the present invention can be obtained by modifying the hollow labyrinth disc with a detachable block or a plastic waterproof material, thereby effectively reducing the adjustment and use costs of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the internal structure of the present invention;

[0022] Figure 2 It is a structural schematic diagram of the present invention;

[0023] Figure 3 It is a structural schematic diagram of the hollow maze disc of the present invention;

[0024] Figure 4 It is a schematic structural diagram of the solid maze disc of the present invention.

[0025] 1. Valve body, 2. Valve cover, 3. Valve cover flange, 4. Valve cover bolts, 5. Valve cover nuts, 6. Valve core, 7. Valve stem, 8. Valve seat, 9. Valve seat ring, 10. Elastic metal gasket, 11. Labyrinth disc assembly, 12. Guide sleeve, 13. Valve core sealing ring, 14. Packing, 15. Packing gasket, 16. Bracket, 17. Actuator, 18. Valve seat basket, 19. Hollow labyrinth disc, 20. Solid labyrinth disc, 21. Labyrinth flow channel, 22. Flow blocking part, 23. Outlet flow channel, 24. Bend. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the following embodiments are merely illustrative in nature, and the present invention is not intended to limit its applicable objects or uses, and the present invention is not limited to the following embodiments.

[0027] Example

[0028] A labyrinth type minimum flow control valve is disclosed. The main structure of the control valve includes a valve body 1, a valve cover 2, a valve core 6, a valve seat 8, a valve stem 7 and an actuator 17. The valve seat 8 and the valve core 6 are arranged in the valve body 1. One end of the valve stem 7 extends into the valve body 1 and is connected to the valve core 6, and the other end extends out of the valve cover 2 and is connected to the actuator 17. In addition, the control valve of the present invention also includes a labyrinth disc assembly 11. The labyrinth disc assembly 11 is fixedly arranged in the valve body 1. The labyrinth disc assembly 11 is sleeved on the peripheral side of the valve core 6. The labyrinth disc assembly 11 includes a plurality of hollow labyrinth discs 19 and a plurality of solid labyrinth discs 20. The hollow labyrinth discs 19 and the solid labyrinth discs 20 are both annular discs. A plurality of labyrinth flow channels 21 are arranged on the annular discs. The hollow labyrinth discs 19 and the solid labyrinth discs 20 are stacked up and down and sleeved on the peripheral side of the valve core 6.

[0029] In this embodiment, a flow blocking member 22 is provided in the labyrinth flow channel 21 of the solid labyrinth disc 20 . The flow blocking member 22 completely blocks the labyrinth flow channel 21 on the solid labyrinth disc 20 , so that no fluid can pass through the solid labyrinth disc 20 .

[0030] The flow blocking member 22 is a detachable block or a plastic waterproof material, which can completely block the labyrinth flow channel on the solid labyrinth disc 20 .

[0031] The outlet of the labyrinth flow channel 21 on the hollow labyrinth disc 19 includes at least one parallel outlet flow channel 23 , and the middle portion of the labyrinth flow channel 21 includes a plurality of curved portions 24 .

[0032] In this embodiment, eight labyrinth flow channels 21 are provided on the annular disc, and each labyrinth flow channel includes two parallel outlet flow channels 23 and four bends 24 .

[0033] For the main structure of the control valve of the present invention, a packing chamber is formed between the valve stem 7 and the valve cover 2, and a packing 14 and a packing gasket 15 are arranged in the packing chamber, a valve core sealing ring 13 is arranged around the valve core 6, a valve cover flange 3, a valve cover bolt 4, and a valve cover nut 5 are arranged around the valve cover 2, and the valve cover 2 and the valve body 1 are fixedly connected by the valve cover flange 3, the valve cover bolt 4, and the valve cover nut 5. A guide sleeve 12 is also arranged in the valve cover 2 for positioning when the valve cover 2 and the valve seat 8 are connected.

[0034] In addition, in order to improve the connection stability and reliability of the control valve, the control valve also includes a valve seat basket 18 and a valve seat ring 9. The valve seat basket 18 is arranged at the bottom of the valve body 1, and the valve seat ring 9 is arranged on the valve seat basket 18. An elastic metal pad 10 is provided on the valve seat ring 9 to cooperate in supporting and sealing the valve seat 8.

[0035] like Figure 2 As shown, a bracket 16 for supporting the actuator 17 is provided at the bottom thereof.

[0036] In this embodiment, the number of hollow labyrinth discs 19 and solid labyrinth discs 20 in the labyrinth disc assembly 11 is the same, so that the actual valve opening is only 50%, which also meets the parameter requirements of the working condition and fundamentally solves the problem of blow damage caused by half (or part) of the valve core being exposed to the environment for a long time.

[0037] When the present invention is used in practice, the valve opening and the corresponding flow requirements can be converted to adjust the number of hollow labyrinth discs 19 and solid labyrinth discs 20 to achieve adjustment of the actual valve opening.

[0038] The above embodiments are merely examples and do not limit the scope of the present invention. These embodiments can also be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the technical concept of the present invention.

Claims

1. An adjustable labyrinth type minimum flow control valve, comprising a valve body (1), a valve cover (2), a valve core (6), a valve seat (8), a valve stem (7) and an actuator (17), wherein the valve seat (8) and the valve core (6) are arranged in the valve body (1), one end of the valve stem (7) extends into the valve body (1) and is connected to the valve core (6), and the other end extends out of the valve cover (2) and is connected to the actuator (17), characterized in that: The control valve further comprises a labyrinth disc assembly (11), wherein the labyrinth disc assembly (11) is fixedly arranged in the valve body (1), the labyrinth disc assembly (11) is sleeved on the circumference of the valve core (6), and the labyrinth disc assembly (11) comprises a plurality of hollow labyrinth discs (19) and a plurality of solid labyrinth discs (20); The solid labyrinth disc (20) is an annular disc, and a plurality of labyrinth flow channels (21) are provided on the annular disc. A flow blocking member (22) is provided inside the labyrinth flow channel (21) of the solid labyrinth disc (20), and the flow blocking member (22) completely blocks the labyrinth flow channel (21) on the solid labyrinth disc (20); The hollow labyrinth disc (19) is an annular disc, and a plurality of labyrinth flow channels (21) are provided on the annular disc; The outlet of the labyrinth flow channel (21) comprises at least one parallel outlet flow channel (23).

2. The adjustable labyrinth type minimum flow control valve according to claim 1, characterized in that: The middle portion of the labyrinth flow channel (21) includes a plurality of curved portions (24).

3. The adjustable labyrinth type minimum flow control valve according to claim 1, characterized in that: The annular disc is provided with 8 labyrinth flow channels (21).

4. The adjustable labyrinth type minimum flow control valve according to claim 1, characterized in that: A packing chamber is formed between the valve stem (7) and the valve cover (2), and packing (14) and packing gasket (15) are arranged in the packing chamber.

5. The adjustable labyrinth type minimum flow control valve according to claim 1, characterized in that: A valve core sealing ring (13) is provided on the circumference of the valve core (6).

6. The adjustable labyrinth type minimum flow control valve according to claim 1, characterized in that: The circumferential side of the valve cover (2) is provided with a valve cover flange (3), a valve cover bolt (4), and a valve cover nut (5); the valve cover (2) and the valve body (1) are fixedly connected by the valve cover flange (3), the valve cover bolt (4), and the valve cover nut (5).

7. The adjustable labyrinth type minimum flow control valve according to claim 1, characterized in that: The number of hollow labyrinth discs (19) and solid labyrinth discs (20) in the labyrinth disc assembly (11) is the same.

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