Sand prevention type flat gate valve

Abstract

The sand prevention type flat gate valve comprises a valve body, a gate plate and a valve rod connected with the top end of the gate plate in a floating mode, pressure self-adaption floating sealing systems are arranged on the two sides of the gate plate, each pressure self-adaption floating sealing system comprises a valve seat assembly capable of moving axially, and full-range sealing from low pressure to ultrahigh pressure is achieved; a dynamic sealing gap is formed between the valve body and the valve seat assembly, and the dynamic sealing gap is configured to prevent sand grains from invading the valve cavity.

Description

Technical Field

[0001] The present invention relates to the technical field of flat gate valves, in particular to a sand-proof flat gate valve. Background Art

[0002] For natural gas production sites such as shale gas and tight gas, in order to establish a stable underground production channel during the mining process, the fracturing process mostly adopts sand fracturing or sand fracturing + acid fracturing. The fracturing process has high pressure and a large amount of fracturing sand. During the natural gas production process after fracturing, the sand that flows back from the well along with the natural gas production will cause great harm to the wellhead equipment and process production equipment of the on-site production pressure control equipment, especially the flat gate valve with the cut-off function in the process.

[0003] However, when the current flat gate valve is in use, fine fracturing sand will enter the gap between the gate valve seat and the valve body, affecting the sealing performance of the product, or enter the valve cavity, causing sand and gravel to accumulate in the gate downward cavity, making it impossible to effectively close the gate, affecting the opening and closing effect of the gate valve, and causing valve sealing failure.

[0004] There are two sealing schemes for flat gate valves, front-valve sealing and back-valve sealing. The existing front-valve sealing structure of flat valves has a large gap between the valve body, gate and valve seat, which makes it easy for sand to enter the gap, resulting in the gate valve seat being unable to float freely, leading to the following two results: Result 1: valve seal failure; Result 2: the valve switching torque of this structure itself is relatively large. After sand enters the gap at one end, the valve seat and gate cannot be aligned, and the switching torque of the valve will be increased, and the valve may even be unable to be switched; the back-valve sealing structure will allow sand and gravel to enter the valve body cavity, and the sand and gravel will accumulate in the valve cavity, and the gate cannot be opened and closed in place. The flat valve is in a semi-open state for a long time, resulting in serious erosion of the sealing surface and valve seal failure. Therefore, valves with back-valve sealing structure are not suitable for the above-mentioned natural gas production stations. Summary of the Invention

[0005] The purpose of the present invention is to provide a sand-proof flat gate valve in order to solve the technical problems existing in the background technology.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A sand-proof flat gate valve, comprising a valve body, a gate plate, and a valve stem in floating connection with the top of the gate plate. A pressure-adaptive floating sealing system is provided on both sides of the gate plate. The pressure-adaptive floating sealing system includes an axially movable valve seat assembly, achieving full-range sealing from low pressure to ultra-high pressure.

[0008] A dynamic sealing gap is formed between the valve body and the valve seat assembly, and the dynamic sealing gap is configured to block sand particles from intruding into the valve cavity.

[0009] In some embodiments, the pressure adaptive floating seal system comprises:

[0010] For L-type valve seat, the effective area of ​​the front face A affected by the fluid is S1, the effective area of ​​the rear face B affected by the fluid is S2, and S1>S2;

[0011] The valve seat bushing is sleeved on the outside of the valve seat, forming an annular space between the two;

[0012] The valve body bushing is connected to the valve seat bushing through fasteners, and a disc spring is arranged between the valve body and the valve seat bushing.

[0013] In some embodiments, the axial length of the annular area is greater than the maximum movement stroke of the valve seat (22).

[0014] In some embodiments, the disc spring is preset between the valve body bushing and the valve body, and its preload force transmission path is:

[0015] Disc spring, valve body bushing, valve seat bushing, valve seat, gate sealing surface.

[0016] In some embodiments, all floating mating surfaces adopt an external cylindrical sealing structure, including:

[0017] The cylindrical mating surface of the valve seat and the valve seat bushing;

[0018] The end butt joint surface between the valve seat bushing and the valve body bushing;

[0019] Stepped mounting surface between the valve body bushing and the valve body.

[0020] In some embodiments, the bottom of the valve body is integrated with an online cleaning module for removing sand accumulated in the valve cavity without stopping production;

[0021] The online cleaning module includes a check valve and a drain port, wherein:

[0022] The sewage outlet passes through the bottom of the valve body and is connected to the valve cavity;

[0023] The one-flow valve is installed outside the sewage outlet and is configured to only allow the medium in the valve cavity to be discharged outward.

[0024] In some embodiments, the valve seat bushing is fastened to the valve body bushing by bolts, and an end portion of the valve seat bushing is kept in a non-contact state with the gate plate.

[0025] The beneficial effects that may be brought about by the sand-proof flat gate valve disclosed in this application include but are not limited to:

[0026] 1. Zero-gap sand prevention: The outer cylindrical sealing structure makes the floating parts assembly gap ≤0.05mm (better than the millimeter-level gap of the end face seal), blocking the intrusion path of sand particles;

[0027] 2. Pressure adaptive seal:

[0028] At low pressure, the disc spring preload is greater than the sealing pressure ratio;

[0029] At high pressure, the differential pressure sealing force automatically increases as the pressure rises;

[0030] 3. Online cleaning: The valve cavity can be cleaned regularly without stopping production or shutting down the well. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall and internal structure of the present invention;

[0032] Figure 2 This is a structural diagram of the valve body check valve and the sewage discharge interface of the present invention;

[0033] Figure 3 This is a schematic structural diagram of the valve seat assembly of the present invention;

[0034] Figure 4 This is the gate valve seat matching diagram of the present invention (marked areas S1, S2, S3 in the fully closed state);

[0035] Figure 5 This is the gate valve seat matching diagram of the present invention (fully open state, the gate is in the open state, located at the downstream end of the valve);

[0036] Figure 6 This is the gate valve seat matching diagram of the present invention (fully open state, the gate is in the open state, located at the downstream end of the valve);

[0037] Figure 7 This is the matching diagram of the gate valve seat of the present invention (fully closed state, the gate is in the closed state, located at the downstream end of the valve).

[0038] Illustration: 1-valve body, 2-valve seat assembly, 3-gate, 21-valve seat bushing, 22-valve seat, 23-valve body bushing, 24-disc spring, 25-annulus area. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0040] On the contrary, this application covers any alternatives, modifications, equivalents, and solutions made within the spirit and scope of this application as defined by the claims. Furthermore, to facilitate a better understanding of this application, certain specific details are described in detail below in the detailed description of this application. Those skilled in the art will be able to fully understand this application without these details.

[0041] like Figure 1-7 As shown, a sand-proof flat gate valve includes a valve body 1, a gate plate 3, and a valve stem floatingly connected to the top of the gate plate 3. A pressure-adaptive floating sealing system is provided on both sides of the gate plate 3. The pressure-adaptive floating sealing system includes an axially movable valve seat 22 assembly 2 to achieve full-range sealing from low pressure to ultra-high pressure;

[0042] A dynamic sealing gap is formed between the valve body 1 and the valve seat 22 assembly 2 , and the dynamic sealing gap is configured to block sand particles from intruding into the valve cavity.

[0043] In some embodiments, the pressure adaptive floating sealing system includes: a valve body bushing 23 is connected between the valve seat 22 and the valve body 1, a valve seat bushing 21 is connected between the valve seat 22 and the valve body bushing 23, an annular space 25 is provided between the valve seat 22 and the valve seat bushing 21, a disc spring 24 is provided between the valve body bushing 23 and the valve body 1, an outer cylindrical seal is adopted between the valve seat 22 and the valve seat bushing 21 and the valve body bushing 23, an outer cylindrical seal is adopted between the valve seat bushing 21 and the valve body bushing 23, and an outer cylindrical seal is adopted between the valve body bushing 23 and the valve body 1. This outer sealing structure solves the defect that the end face sealing structure requires a certain gap between the end faces to achieve sealing, and can fully reduce the gap between all floating valve components, and can even achieve zero gap or infinitely close to zero gap;

[0044] The valve seat 22 is L-shaped. The effective area of ​​its front face A, where fluid acts, is S1, and the effective area of ​​its rear face B, where fluid acts, is S2, with S1 > S2. The valve seat bushing 21 is sleeved around the outside of the valve seat 22, forming an annulus 25 between them. The axial length of the annulus 25 is greater than the maximum travel of the valve seat 22. The valve body bushing 23 is connected to the valve seat bushing 21 via fasteners.

[0045] In some embodiments, the disc spring 24 is preset between the valve body bushing 23 and the valve body 1, and its preload force transmission path is: disc spring 24 → valve body bushing 23 → valve seat bushing 21 → valve seat 22 → gate 3 sealing surface.

[0046] All floating mating surfaces adopt external cylindrical seal structure, including:

[0047] The cylindrical mating surface between the valve seat 22 and the valve seat bushing 21;

[0048] The end butt joint surface between the valve seat bushing 21 and the valve body bushing 23;

[0049] The stepped mounting surface between the valve body bushing 23 and the valve body 1 .

[0050] The function of the disc spring 24 is to apply an axial preset thrust to the body bushing when the valve is operated at low pressure, and transmit the force to the valve seat 22 through the contact surface between the body bushing and the valve seat 22, so that the valve can be sealed more reliably under low pressure conditions; see Figure 3 .

[0051] The valve seat bushing 21 and the valve body bushing 23 are connected by using bolts to ensure that the valve seat bushing 21 does not contact the gate plate 3 .

[0052] See also Figure 4 , Figure 4 The valve seat 22 is L-shaped, with the area S3 at F3 being smaller than the area S2 at F2. Similarly, it is also smaller than the area S1 at F1 of the valve body bushing 23. Furthermore, the combination of the valve seat 22 and the bushing forms an annular space 25 that facilitates the forward and backward movement of the valve seat 22.

[0053] See also Figure 7 During operation, when the valve is open, the fluids in the valve cavity and the gate 3 hole generally have the same pressure. The fluid exerts an axial pressure F2 on the surface of the valve seat 22 at the A joint (the direction of the force is the same as the arrow).

[0054] At the same time, the same axial pressure F3 is applied to the valve seat 22B end. A pressure F4 is also applied to the surface of the valve seat bushing 21, which is axially the same as the pressure F3.

[0055] Due to the different surface areas at both ends of the valve seat 22, A and B, the total pressure (pressure multiplied by surface area) exerted by pressure F2 is greater than the total pressure exerted by pressure F3. This pressure difference causes the valve seat 22 to be pushed toward the gate 3, forming a sealed fit with the gate 3 at position B. In addition, as the internal pressure increases, the difference in force exerted by pressure F2 and pressure F3 will also increase. Therefore, the sealing performance of the valve will improve as the internal pressure increases. For details, see Figure 5 .

[0056] Although the pressure F4 acts in opposite directions to the pressure F2, it does not interfere with the sealing fit between the valve seat 22 and the gate plate 3. The principle is as follows:

[0057] 1. See Figure 6 , the shoulder of the valve seat bushing 21 and the valve body bushing 23 form a fit at position H. Since the surface areas of the valve body bushing 23 at both ends in contact with the fluid are the same, the fluid pressure in the entire flow channel, that is, P at all positions, is equal. Therefore, the thrusts generated by force F6 and force F1 are equal, but act in opposite directions, and thus cancel each other out.

[0058] 2. A thrust F4 is applied to the end face of the valve seat bushing 21. Through contact transmission at position H, after offsetting the reaction force of the valve body bushing 23, the bushing assembly (valve seat bushing 21 and valve body bushing 23) is pushed backward under the action of the total force, causing the valve body bushing 23 to axially fit with the valve body 1 at position C.

[0059] 3. At the same time, due to the presence of the annular space 25, the surface of the bushing cannot contact the valve seat 22 during its backward movement, so no backward thrust is generated on the valve seat 22. Therefore, the pressure F4 will not interfere with the sealing engagement between the valve seat 22 and the valve plate.

[0060] 4. The principle of the upstream side of the valve is basically the same as that of the downstream side, and its working principle has nothing to do with whether the valve is in the open or closed position. Figure 6 .

[0061] When the valve is in the closed position, the seal is maintained on the downstream side of the gate 3. If the upstream and downstream pressures are equal when the gate 3 is closed, the pressures on the upstream and downstream sides of the gate 3 remain the same, and the sealing mechanism is basically the same as when the gate 3 is open.

[0062] If the pressures are not equal, the upstream pressure exceeds the downstream pressure. The gate 3 is pushed by the upstream fluid pressure and exerts an axial pressure F3 on the valve seat 22 at position B, but there is basically no pressure in the opposite direction of F3.

[0063] Due to the contact between the valve body bushing 23 and the valve seat 22 at position A, the valve seat 22 will generate a pressure F7 on the valve body bushing 23. At this time, the pressure F7 at this position is equal to the axial pressure F3 exerted by the gate 3 on the valve seat 22 at position B. The pressure of F7 will make the valve body bushing 23 fit tightly with the valve body 1. Therefore, under the action of pressure F3, the gate 3 will be forced to fit closely with the valve seat 22. In this way, when the gate 3 is in the closed position, the upstream and downstream sides of the gate 3 will be sealed. For details, see Figure 7 .

[0064] A check valve and a sewage outlet are provided at the bottom of the valve body 1. The valve can be used to clean the valve cavity regularly without stopping production or shutting down the well; see Figure 2 .

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A sand-proof flat gate valve, comprising a valve body (1), a gate plate (3) and a valve stem (6) connected to the top of the gate plate in a floating manner, characterized in that: A pressure-adaptive floating sealing system is provided on both sides of the gate plate (3), and the pressure-adaptive floating sealing system includes an axially movable valve seat assembly (2) to achieve full-range sealing from low pressure to ultra-high pressure; A dynamic sealing gap is formed between the valve body (1) and the valve seat assembly (2), and the dynamic sealing gap is configured to block sand particles from invading the valve cavity.

2. The sand-proof flat gate valve according to claim 1, characterized in that: The pressure adaptive floating seal system comprises: The L-shaped valve seat (22) has an effective area S1 at its front end face A affected by the fluid, and an effective area S2 at its rear end face B affected by the fluid, and S1 > S2; The valve seat bushing (21) is sleeved on the outside of the valve seat (22), and an annular space is formed between the two; The valve body bushing (23) is connected to the valve seat bushing (21) via a fastener, and a disc spring is provided between the valve body (1).

3. The sand-proof flat gate valve according to claim 2, characterized in that: The axial length of the annular space is greater than the maximum movement stroke of the valve seat (22).

4. The sand-proof flat gate valve according to claim 2 or 3, characterized in that: The disc spring is preset between the valve body bushing (23) and the valve body (1), and its preload force transmission path is: Disc spring, valve body bushing (23), valve seat bushing (21), valve seat (22), gate (3) sealing surface.

5. The sand-proof flat gate valve according to claim 2, characterized in that: All floating mating surfaces adopt external cylindrical seal structure, including: a cylindrical mating surface between the valve seat (22) and the valve seat bushing (21); an end butting surface between the valve seat bushing (21) and the valve body bushing (23); The stepped mounting surface between the valve body bushing (23) and the valve body (1).

6. The sand-proof flat gate valve according to claim 1, characterized in that: The bottom of the valve body (1) is integrated with an online cleaning module for clearing sand accumulated in the valve cavity without stopping production; The online cleaning module includes a check valve and a drain port, wherein: The sewage outlet passes through the bottom of the valve body (1) and is connected to the valve cavity; The one-flow valve is installed outside the sewage outlet and is configured to only allow the medium in the valve cavity to be discharged outward.

7. The sand-proof flat gate valve according to claim 2, characterized in that: The valve seat bushing (21) and the valve body bushing (23) are fastened together by bolts, and the end of the valve seat bushing (21) and the gate plate (3) are kept in a non-contact state.

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