Anti-backflow type one-way valve for oil field well head

Abstract

The present application relates to the technical field of valve, especially to an anti-backflow single valve for oilfield wellhead. It comprises a valve body, a valve seat fixed in the valve body, a valve rod provided on the valve seat, a valve flap fixed on the end of the valve rod away from the valve seat, a first spring provided between the valve rod and the valve seat, an elastic ring fixed on the outer circumferential side of the valve flap, a limiting rod sealingly and rotatably connected with the valve body, and a guide surface provided on the limiting rod. The limiting rod limits the elastic ring, and additional resistance is applied to the opening of the valve flap. Thus, the opening threshold of the valve flap is increased without increasing the rigidity of the first spring, the valve flutter caused by the pressure fluctuation in the pipe is reduced, the sealing surface of the valve is protected, the service life of the valve is prolonged, and the flow pressure drop and flow resistance are reduced after the valve is opened.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and in particular to an anti-backflow check valve for oilfield wellheads. Background Technology

[0002] A check valve, also known as a one-way valve, primarily functions to restrict the unidirectional flow of a medium and automatically closes when the flow direction reverses, thus ensuring system safety. In oilfield wellhead systems, check valves are typically installed downstream of the main valve in the wellbore to prevent crude oil, water, and natural gas from flowing back into the wellbore. The valve opens using the pressure of the fluid flowing in the forward direction; once the flow direction changes or the flow velocity falls below a set value, the valve quickly closes under the combined action of the spring force and the backflowing medium, effectively blocking backflow. However, in actual operating conditions, due to the pulsating characteristics of the pumping unit, the instability of multiphase fluid flow, and the heterogeneity of the reservoir, the fluid pressure in the pipeline usually fluctuates frequently. If the spring stiffness inside the check valve is too low, the valve disc will exhibit oversensitivity, triggering opening and closing even with slight pressure fluctuations, leading to continuous valve disc flutter. This high-frequency impact will severely damage the valve disc, seat, and sealing surface, ultimately causing premature valve failure and a decline in sealing performance. To mitigate chatter, increasing spring stiffness is commonly used to raise the valve's opening pressure threshold. While this measure helps suppress chatter, the increased spring stiffness raises the pressure required to open the valve, leading to a higher overall system pressure drop. Summary of the Invention

[0003] This invention provides an anti-backflow check valve for oilfield wellheads to overcome the drawback of large pressure drop in existing check valves used in oilfield wellheads.

[0004] The technical solution of the present invention is as follows: a backflow prevention single-flow valve for oilfield wellheads, comprising: a valve body, a valve seat fixedly connected to the valve body, a valve stem provided on the valve seat, a valve disc fixedly connected to the end of the valve stem away from the valve seat, the valve disc contacting the valve body and used to seal the valve body, a first spring provided between the valve stem and the valve seat, an elastic ring fixedly connected to the outer periphery of the valve disc, a limit rod rotatably connected to the valve body, a guide surface provided on the limit rod, the guide surface of the limit rod contacting the elastic ring, a guide block fixedly connected to the valve body, the guide block contacting the limit rod and used to guide the elastic ring.

[0005] Furthermore, in the vertical direction, the minimum distance between the guide surface of the limiting rod and the valve disc is greater than the wall thickness of the elastic ring.

[0006] Furthermore, the valve stem is fixedly connected to a first guide bar and a second guide bar that are evenly distributed in a ring. The number of the first guide bar and the second guide bar are equal. The first guide bar and the second guide bar are both inclined in opposite directions. All the first guide bars and all the second guide bars are staggered. A fixing sleeve is fixedly connected to the side of the valve seat near the valve disc. A plurality of fixing blocks are evenly distributed in a ring on the inner side of the fixing sleeve. The valve seat is slidably and rotatably connected to the valve stem. The fixing blocks are used to squeeze the first guide bar and the second guide bar to make the valve stem rotate.

[0007] Furthermore, the number of the first guide strips is an integer multiple of the number of the fixed blocks.

[0008] Furthermore, a fixed friction ring is fixedly connected to the valve body near the limiting rod, and a moving friction ring is splined to the limiting rod and contacts the fixed friction ring. There is friction between the fixed friction ring and the moving friction ring. An adjusting member is threaded to the limiting rod and contacts the moving friction ring. The adjusting member is used to squeeze the moving friction ring to control the magnitude of the friction between the fixed friction ring and the moving friction ring.

[0009] Furthermore, a magnetic ring is fixed to the side of the valve seat near the valve disc, and the valve disc is made of magnetic material.

[0010] Furthermore, the outer side of the magnetic ring is wrapped with an elastic sleeve, which is used to prevent the valve disc from directly contacting the magnetic ring.

[0011] Furthermore, a buffer disc is slidably connected inside the valve disc, the buffer disc is limited and slidably connected to the valve stem, an elastic arc strip is fixed inside the valve disc and contacts the buffer disc, and the valve disc is provided with a damping hole.

[0012] Furthermore, a fixed seat is fixedly connected inside the damping hole, and an adjusting frustum is slidably connected to the fixed seat. A second spring is fixedly connected between the adjusting frustum and the fixed seat.

[0013] Furthermore, the circumference of the adjusting frustum is provided with uniformly distributed protrusions, which are used to increase the flow resistance of liquid when it flows between the adjusting frustum and the damping orifice.

[0014] The beneficial effects of adopting the above technical solution are as follows: the present invention relies on the limiting effect of the limiting rod on the elastic ring to apply additional resistance to the opening of the valve disc. In this way, while increasing the valve disc opening threshold, there is no need to increase the stiffness of the first spring. This can reduce valve chatter caused by pressure fluctuations in the pipe, protect the valve sealing surface, extend the service life of the valve, and reduce the flow pressure drop and flow resistance after the valve is opened.

[0015] By relying on the attraction of the magnetic ring on the valve disc, the frequency of the valve disc's reciprocating movement due to pressure fluctuations is reduced when the valve is open, thereby reducing the number of times the valve disc collides with the valve seat and lowering the wear rate of the valve disc and valve seat.

[0016] The system absorbs the impact of water hammer on the buffer disc by relying on the elastic deformation of the elastic arc strip. In addition, the fluid between the buffer disc and the valve disc is squeezed to flow through the damping hole. The resistance of the fluid flow further absorbs the impact of water hammer, thus reducing the damage caused by water hammer to the device and pipeline. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0018] Figure 2 This is a three-dimensional structural diagram of the valve disc and elastic ring of the present invention;

[0019] Figure 3 This is a three-dimensional structural cross-sectional view of the elastic ring and limiting rod of the present invention;

[0020] Figure 4 This is a three-dimensional structural cross-sectional view of the limiting rod and guide block of the present invention;

[0021] Figure 5 This is a three-dimensional structural cross-sectional view of the fixing sleeve and fixing block of the present invention;

[0022] Figure 6 This is a three-dimensional structural cross-sectional view of the dynamic friction ring and adjusting component of the present invention;

[0023] Figure 7 This is a three-dimensional structural diagram of the fixed base and the adjusting frustum of the present invention.

[0024] The components in the diagram are labeled as follows: 1-valve body, 2-valve seat, 3-valve stem, 4-valve disc, 5-first spring, 6-elastic ring, 7-limiting rod, 8-guide block, 9-first guide bar, 10-second guide bar, 11-fixed sleeve, 12-fixed block, 13-fixed friction ring, 14-moving friction ring, 15-adjusting component, 16-magnetic ring, 17-elastic sleeve, 18-buffer disc, 19-elastic arc bar, 20-fixed seat, 201-damping hole, 21-adjusting frustum, 22-second spring, 23-protruding ridge. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments. Example 1

[0026] This embodiment discloses an anti-backflow check valve for oilfield wellheads to solve the problem of large pressure drop in existing check valves used in oilfield wellheads.

[0027] See Figures 1 to 4 A backflow prevention check valve for oilfield wellheads includes: a valve body 1, a valve seat 2 fixedly connected inside the valve body 1, a valve stem 3 provided on the valve seat 2, and a valve disc 4 fixedly connected to the left end of the valve stem 3. When the check valve is in the closed state, the valve disc 4 contacts the valve body 1 and is used to block the valve body 1. When the check valve is in the open state, the valve disc 4 loses contact with the valve body 1, and fluid can flow between the valve body 1 and the valve disc 4. A first spring 5 is provided between the valve stem 3 and the valve seat 2, and an elastic ring 6 is fixedly connected to the outer periphery of the valve disc 4. The elastic ring 6 is made of elastic metal and is variable in shape. The outer and inner diameters of the elastic ring 6 gradually increase from left to right. The valve body 1 is sealed and rotatably connected to a limit rod 7. A guide surface is provided in the middle of the limit rod 7. The guide surface of the limit rod 7 contacts the elastic ring 6. A guide block 8 is fixedly connected to the upper side inside the valve body 1. The guide block 8 contacts the limit rod 7 and is used to guide the deformation of the elastic ring 6. The angle between the guide surface of the limit rod 7 and the horizontal plane is greater than the angle between the lower side of the guide block 8 and the horizontal plane, making it easy for the elastic ring 6 to pass over the limit rod 7 from right to left, but difficult to pass over the limit rod 7 from left to right.

[0028] The above setup enables the limiting rod 7 to limit the elastic ring 6, thereby applying additional resistance to the opening of the valve disc 4. This increases the valve disc 4 opening threshold without increasing the stiffness of the first spring 5, which can reduce valve chatter caused by pressure fluctuations in the pipe, protect the valve sealing surface, extend the valve's service life, and reduce flow pressure drop and flow resistance after the valve is opened.

[0029] It should be noted that in this embodiment, the valve seat 2 and the valve stem 3 can be considered as a sliding connection.

[0030] See Figure 4 In the vertical direction, the minimum distance between the guide surface of the limiting rod 7 and the valve disc 4 is greater than the wall thickness of the elastic ring 6, so that the elastic ring 6 can pass over the limiting rod 7 after deformation.

[0031] Operating Procedure: Install valve body 1 into the pipeline via flange. The fluid (crude oil) in the pipeline flows from left to right. When the pressure of the fluid on the left side of the pipeline fluctuates, if the peak pressure of the fluid on the left side of the pipeline is less than the threshold for opening valve disc 4, valve disc 4 remains stationary and maintains a blocking state on valve body 1. If the peak pressure of the fluid on the left side of the pipeline is greater than the threshold for opening valve disc 4, valve disc 4 moves to the right limit position under the action of fluid pressure. At this time, valve disc 4 releases the blockage on valve body 1, and the fluid on the left side of the pipeline flows to the right through the gap between valve body 1 and valve disc 4. During the process of the fluid flowing to the right, it always exerts a rightward fluid drag force on valve disc 4. Valve disc 4 maintains a balanced state under the rightward fluid drag force of the fluid and the leftward elastic force of the first spring 5. As the fluid velocity in the pipeline decreases, valve disc 4 gradually moves to the left. Finally, valve disc 4 drives the elastic ring 6 to cross the limit rod 7 and reach the left limit position.

[0032] During the rightward movement of valve disc 4, valve disc 4 drives valve stem 3 to move to the right, compressing the first spring 5. Valve disc 4 drives elastic ring 6 to move to the right, causing the upper part of elastic ring 6 to deform under the pressure of the guide surface of limit rod 7. After elastic ring 6 passes the limit rod 7, elastic ring 6 restores its shape under its own elasticity. In this way, by using the limiting effect of limit rod 7 on elastic ring 6, the threshold for opening valve disc 4 is increased, thereby suppressing valve chatter without increasing the stiffness of the first spring 5. Example 2

[0033] This embodiment, based on embodiment 1, provides the function of changing the contact position between the elastic ring 6 and the limiting rod 7, thereby extending the number of uses of the elastic ring 6.

[0034] See Figures 3 to 5 The valve stem 3 has nine uniformly distributed first guide bars 9 and two uniformly distributed second guide bars 10 fixedly connected to its middle section. The first guide bars 9 and the second guide bars 10 are staggered. From left to right, the first guide bars 9 are tilted counterclockwise along the central axis of the valve stem 3 (the rotation angle in this paper is from right to left), and the second guide bars 10 are tilted in the opposite direction to the first guide bars 9. The valve seat 2 is slidably and rotatably connected to the valve stem 3. A fixing sleeve 11 is fixedly connected to the left side of the middle section of the valve seat 2, and multiple uniformly distributed fixing blocks 12 are fixedly connected to the inner side of the fixing sleeve 11. The number of first guide bars 9 is an integer multiple of the number of fixed blocks 12. In this paper, the number of fixed blocks 12 is three and they are evenly distributed in a ring. The fixed blocks 12 apply a uniform circumferential torsional force to the valve stem 3 through the first guide bars 9 and the second guide bars 10. The fixed blocks 12 are used to squeeze the first guide bars 9 and the second guide bars 10 to make the valve stem 3 rotate. When the valve disc 4 moves to the right until it reaches the right limit position (the right limit position in this paper refers to the position corresponding to when the valve disc 4 can no longer move to the right, and the left limit position is the position shown in the figure), the fixed blocks 12 pass over the second guide bar 10 and the first guide bar 9 in sequence.

[0035] The above setup enables the valve stem 3 to rotate by relying on the guidance of the first guide bar 9 and the second guide bar 10 by the fixing block 12, so that the position of the elastic ring 6 corresponding to the limiting rod 7 changes, thus making the position of the elastic ring 6 different each time it deforms, and extending the number of times the elastic ring 6 deforms. Example 3

[0036] This embodiment, based on embodiment 2, provides the function of changing the tilt angle of the guide surface of the limit rod 7 to achieve the purpose of controlling the valve opening threshold.

[0037] See Figure 1 , Figure 2 and Figure 6 A fixed friction ring 13 is fixedly connected to the outer side of the valve body 1. A moving friction ring 14 that contacts the fixed friction ring 13 is splined to the front of the limiting rod 7. There is friction between the fixed friction ring 13 and the moving friction ring 14. An adjusting member 15 that contacts the moving friction ring 14 is threaded to the front of the limiting rod 7. The adjusting member 15 is used to squeeze the moving friction ring 14 to control the magnitude of the friction between the fixed friction ring 13 and the moving friction ring 14.

[0038] The above settings enable the rotation of the limiting rod 7 to control the tilt angle of the guide surface on the limiting rod 7, thereby changing the angle formed between the elastic ring 6 and the guide surface of the limiting rod 7. This achieves the purpose of controlling the limiting force of the limiting rod 7 on the elastic ring 6, and thus controlling the threshold for opening the valve disc 4.

[0039] The process for changing the tilt angle of the guide surface on the limit rod 7 is as follows: Use a tool to rotate the adjusting member 15, causing the adjusting member 15 to move forward and reduce the squeezing force on the moving friction ring 14, thereby reducing the friction between the moving friction ring 14 and the fixed friction ring 13. Then, use a tool to rotate the limit rod 7 and the moving friction ring 14 to adjust the tilt angle of the guide surface on the limit rod 7 to the specified angle. Then, use a tool to keep the limit rod 7 stationary and rotate the adjusting member 15 in the opposite direction, causing the adjusting member 15 to squeeze the moving friction ring 14 backward and increase the friction between the moving friction ring 14 and the fixed friction ring 13 until the friction between the moving friction ring 14 and the fixed friction ring 13 is sufficient to keep the limit rod 7 stable when squeezed by the elastic ring 6. Then, stop rotating the adjusting member 15. This completes the adjustment of the tilt angle of the guide surface on the limit rod 7. Example 4

[0040] This embodiment provides a rapid closure function based on embodiment 3, reducing the probability of fluid backflow.

[0041] If the stiffness of the internal spring of the current axial flow check valve is low during use, the valve disc 4 will reciprocate and frequently collide with the valve seat 2 due to pressure fluctuations in the pipeline during valve opening, resulting in accelerated valve wear rate.

[0042] See Figure 3 A magnetic ring 16 is fixed to the left side of the valve seat 2. The valve disc 4 is made of magnetic material. When the valve disc 4 is in the right extreme position, the attraction of the magnetic ring 16 on the valve disc 4 offsets part of the elastic force of the first spring 5, so that the valve disc 4 can still maintain a stable state within a certain pressure fluctuation range (the pressure fluctuation range is determined by the magnetic attraction between the magnetic ring 16 and the valve disc 4 and the elastic force of the first spring 5 when the valve disc 4 is in the right extreme position). An elastic sleeve 17 is wrapped around the outside of the magnetic ring 16. The elastic sleeve 17 is used to prevent the valve disc 4 from directly contacting the magnetic ring 16.

[0043] The above configuration can reduce the frequency of valve disc 4 reciprocating due to pressure fluctuations when the valve is open by relying on the attraction of the magnetic ring 16 on the valve disc 4, thereby reducing the number of times the valve disc 4 collides with the valve seat 2 and reducing the wear rate of the valve disc 4 and the valve seat 2. Example 5

[0044] This embodiment, based on embodiment 4, provides the function of reducing the impact force of water hammer on valve disc 4.

[0045] See Figure 3 , Figure 4 and Figure 7 A buffer disc 18 is slidably connected to the right side of the valve disc 4. The buffer disc 18 is limited and slidably connected to the valve stem 3. An elastic arc strip 19 is fixed inside the valve disc 4 and contacts the buffer disc 18. The elastic arc strip 19 is made of elastic metal. When the elastic arc strip 19 is subjected to a leftward compressive force, the elastic arc strip 19 can undergo elastic deformation from the middle and store force. The valve disc 4 is provided with a damping hole 201, which connects the inside of the valve disc 4 to the left side of the pipeline. When the device is in operation... When the fluid being processed is crude oil, a circular elastic sheet can be adhered to the left side of the valve disc 4. The elastic sheet is only adhered to the valve disc 4 at its edge (because crude oil contains impurities that can easily clog the damping hole 201, the elastic sheet can be used to isolate the inside of the valve disc 4 from the crude oil). Liquid medium is stored between the valve disc 4 and the buffer plate 18. When the buffer plate 18 moves to the left relative to the valve disc 4, the medium between the valve disc 4 and the buffer plate 18 can be temporarily stored between the valve disc 4 and the elastic sheet through the damping hole 201.

[0046] See Figure 7 A fixed seat 20 is fixedly connected inside the damping hole 201. An adjusting frustum 21 is slidably connected to the fixed seat 20. A second spring 22 is fixedly connected between the adjusting frustum 21 and the fixed seat 20.

[0047] The above configuration enables the elastic deformation of the elastic arc strip 19 to absorb the impact force of water hammer on the buffer disc 18. In addition, the buffer disc 18 squeezes the fluid between itself and the valve disc 4 to flow through the damping hole 201, and uses the resistance of the fluid flow to further absorb the impact force of water hammer, thereby reducing the damage caused by water hammer impact force to the device and pipeline.

[0048] See Figure 7 The circumference of the adjusting frustum 21 is provided with evenly distributed protrusions 23, which are used to increase the flow resistance of liquid when it flows between the adjusting frustum 21 and the damping hole 201.

[0049] The above configuration enables the increased fluid drag force on the regulating frustum 21 by the protrusion 23 during fluid flow. As the fluid flows between the regulating frustum 21 and the damping hole 201, it can drive the regulating frustum 21 to move, thereby changing the flow area between the regulating frustum 21 and the damping hole 201. This allows the fluid flow resistance to be adjusted automatically according to the magnitude of the water hammer impact on the buffer plate 18, absorbing the impact force of the water hammer to the greatest extent.

[0050] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A backflow prevention check valve for oilfield wellheads, characterized in that, include: A valve body (1) is provided with a valve seat (2) fixed inside the valve body (1). A valve stem (3) is provided on the valve seat (2). A valve disc (4) is fixed on one end of the valve stem (3) away from the valve seat (2). The valve disc (4) contacts the valve body (1) and is used to block the valve body (1). A first spring (5) is provided between the valve stem (3) and the valve seat (2). An elastic ring (6) is fixed on the outer periphery of the valve disc (4). A limit rod (7) is sealed and rotatably connected to the valve body (1). A guide surface is provided on the limit rod (7). The guide surface of the limit rod (7) contacts the elastic ring (6). A guide block (8) is fixed on the valve body (1). The guide block (8) contacts the limit rod (7) and is used to guide the deformation of the elastic ring (6). In the vertical direction, the minimum distance between the guide surface of the limiting rod (7) and the valve disc (4) is greater than the wall thickness of the elastic ring (6); A fixed friction ring (13) is fixedly connected to the valve body (1) near the limiting rod (7). The limiting rod (7) is splined to a moving friction ring (14) that contacts the fixed friction ring (13). There is friction between the fixed friction ring (13) and the moving friction ring (14). The limiting rod (7) is threaded to an adjusting member (15) that contacts the moving friction ring (14). The adjusting member (15) is used to squeeze the moving friction ring (14) to control the magnitude of the friction between the fixed friction ring (13) and the moving friction ring (14). A magnetic ring (16) is fixed to the side of the valve seat (2) near the valve disc (4), and the valve disc (4) is made of magnetic material; The valve disc (4) is sealed and slidably connected to a buffer disc (18). The buffer disc (18) is limited and sealed to the valve stem (3). An elastic arc strip (19) that contacts the buffer disc (18) is fixedly connected inside the valve disc (4). The valve disc (4) is provided with a damping hole (201).

2. The anti-backflow check valve for oilfield wellheads according to claim 1, characterized in that, The valve stem (3) is fixedly connected to a first guide bar (9) and a second guide bar (10) that are evenly distributed in a ring. The number of the first guide bar (9) and the second guide bar (10) are equal. The first guide bar (9) and the second guide bar (10) are both inclined and in opposite directions. All the first guide bars (9) and all the second guide bars (10) are staggered. The valve seat (2) is fixedly connected to a fixing sleeve (11) on the side near the valve disc (4). The inner side of the fixing sleeve (11) is fixedly connected to a plurality of fixing blocks (12) that are evenly distributed in a ring. The valve seat (2) and the valve stem (3) are slidably and rotatably connected. The fixing blocks (12) are used to squeeze the first guide bar (9) and the second guide bar (10) to make the valve stem (3) rotate.

3. A backflow prevention check valve for oilfield wellheads according to claim 2, characterized in that, The number of the first guide strips (9) is an integer multiple of the number of the fixed blocks (12).

4. The anti-backflow check valve for oilfield wellheads according to claim 1, characterized in that, The outer side of the magnetic ring (16) is wrapped with an elastic sleeve (17), which is used to prevent the valve disc (4) from directly contacting the magnetic ring (16).

5. A backflow prevention check valve for oilfield wellheads according to claim 1, characterized in that, A fixed seat (20) is fixedly connected inside the damping hole (201), and an adjusting frustum (21) is slidably connected to the fixed seat (20). A second spring (22) is fixedly connected between the adjusting frustum (21) and the fixed seat (20).

6. A backflow prevention check valve for oilfield wellheads according to claim 5, characterized in that, The adjusting frustum (21) is provided with uniformly distributed protrusions (23) on its periphery. The protrusions (23) are used to increase the flow resistance of liquid when it flows between the adjusting frustum (21) and the damping hole (201).

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