Gate valve suitable for geothermal wellhead

Abstract

The utility model discloses a gate valve suitable for a geothermal well mouth, which comprises a gland, a valve body, an upper valve cover, a valve rod penetrating through the upper valve cover, a gate plate arranged at the lower end part of the valve rod and a valve seat arranged in the valve body, a hydraulic driving mechanism is arranged above the upper valve cover, the hydraulic driving mechanism comprises a cylinder body and a piston, and the piston is arranged in the cylinder body. The top of the upper valve cover is provided with an upper flange, the barrel is located between the gland and the upper flange, a movement cavity for the piston to move is formed among the barrel, the gland and the upper flange, the piston is fixed to the upper end of the valve rod in a sleeving mode, the piston is used for dividing the movement cavity into an upper movement cavity and a lower movement cavity, and the upper movement cavity and the lower movement cavity are communicated through the upper movement cavity and the lower movement cavity. A first communicating hole and a second communicating hole are formed in the positions, corresponding to the upper moving cavity and the lower moving cavity, of the cylinder body respectively, penetrate through the wall thickness direction of the cylinder body and communicate with a hydraulic station.

Description

Technical Field

[0001] The utility model relates to the field of valve technology, and in particular to a high-temperature (above 300°C, 345°C) metal-sealed double-acting hydraulic gate valve suitable for geothermal wellheads. The metal seal here refers to the metal seal between a gate plate and a valve seat, and no soft seal is used. Background Art

[0002] The existing geothermal wellhead gate valve is installed in high-temperature environments such as geothermal wellheads and is a key component located between the production system and the ground pipeline. Due to the high temperature of the wellhead mining medium, conventional soft seals cannot withstand the high temperature of 345°C and cannot be sealed. The valve pressure is high and the diameter is large. The traditional high-temperature expansion valve uses a handwheel operation method, and the large-diameter high-pressure gate valve uses manual opening / closing of the valve. The valve requires a very high torque, and it is difficult and time-consuming to manually open and close the valve. At the same time, because the geothermal temperature reaches 345°C, the actual use of the valve has very high requirements for sealing, and the service life of the valve needs to be considered, and there are more stringent requirements for the structural design of important parts.

[0003] For example, the large-diameter high-temperature expansion gate valve for geothermal wellheads with application number 201520849432.X drives the gate plate to move up and down to open / close the valve by rotating the handwheel. The metal seal between the valve cover and the valve body is a waterline seal, which is suitable for low-pressure valves. At the same time, in the actual on-site use of large-diameter high-pressure valves, operators need to use a lot of force and a long time to open / close the valve.

[0004] Another example is a small-caliber open gate valve with application number 201820218144.8, in which the gate and valve seat are connected by threads, and the gate and valve stem are fixed by pin holes. However, because the valve stem and pins fix the gate, the displacement space of the gate is limited. Utility Model Content

[0005] In view of this, in order to overcome the defects of the above-mentioned prior art, the purpose of the utility model is to provide a gate valve suitable for a geothermal wellhead, which can achieve high-temperature stable sealing and convenient valve opening and closing.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A gate valve suitable for geothermal wellheads, comprising a valve body, a gland, an upper valve cover, a valve stem penetrating the upper valve cover, a gate plate arranged at the lower end of the valve stem, and a valve seat arranged in the valve body, wherein the gland is located above the upper valve cover, the valve stem is used to drive the gate plate to move to realize the opening and closing of the gate valve, a cavity is provided between the valve body and the upper valve cover, the gate plate and the valve seat are accommodated in the cavity, a hydraulic drive mechanism is provided above the upper valve cover, the upper end of the valve stem extends upward into the hydraulic drive mechanism, the hydraulic drive mechanism comprises a cylinder, a gland and a piston, the top of the upper valve cover has an upper flange, the cylinder is located in the A motion cavity for the movement of the piston is formed between the pressure cover and the upper flange, and the cylinder, the pressure cover and the upper flange. The piston is sleeved and fixed on the upper end of the valve stem. The piston is used to divide the motion cavity into an upper motion cavity and a lower motion cavity. The cylinder is respectively provided with a first connecting hole and a second connecting hole corresponding to the upper motion cavity and the lower motion cavity. The first connecting hole and the second connecting hole penetrate the wall thickness direction of the cylinder. The first connecting hole and the second connecting hole are connected with the hydraulic station to inject hydraulic medium into the upper motion cavity or the lower motion cavity to drive the piston to move, thereby realizing the movement of the valve stem. There is a metal seal between the valve seat and the valve body.

[0008] According to some preferred implementation aspects of the utility model, a first annular groove is provided on the inner wall of the upper movement cavity corresponding to the first connecting hole; and / or a second annular groove is provided on the inner wall of the lower movement cavity corresponding to the second connecting hole.

[0009] Preferably, the first connecting hole and the corresponding first annular groove, the second connecting hole and the corresponding second annular groove are respectively arranged at the top and the bottom of the motion cavity to avoid the problem of excessive driving pressure caused by the top of the piston being too close to the bottom surface of the pressure cover, the bottom of the piston being too close to the top surface of the upper flange or being too close to the connecting hole.

[0010] More preferably, the top of the first packing gland is higher than the top of the upper flange and extends into the movement cavity; a notch is provided on the outer edge of the top of the piston to avoid the problem of excessive oil injection resistance caused by the piston being in close contact with the bottom surface of the gland, the top surface of the upper flange, and the connecting hole. The setting of the annular groove and the notch and the extension of the top of the first packing gland can effectively cause water hammer phenomenon in the hydraulic oil after injection, reduce the impact effect of the hydraulic oil itself, and effectively reduce the movement error.

[0011] According to some preferred implementation aspects of the utility model, the upper valve cover includes a cover body and a first extension portion extending upward from the cover body, the upper flange is arranged on the top of the first extension portion, a first sealing assembly is arranged between the valve stem and the first extension portion, the first sealing assembly includes an upper packing and a lower packing, and the upper packing and / or the lower packing includes a lip seal ring or a plurality of lip seal rings stacked up and down. A first packing gland is arranged between the valve stem and the first extension portion and the upper flange.

[0012] According to some preferred implementation aspects of the utility model, there is a gap between the upper filler and the lower filler, and an injection valve for injecting a middle filler into the gap is provided on the first extension portion corresponding to the gap between the upper filler and the lower filler. The middle filler is graphite.

[0013] According to some preferred implementation aspects of the utility model, the bottom surface of the lower filler is higher than the top surface of the cover body.

[0014] Preferably, the bottom surface of the lower packing is higher than half of the overall height of the upper valve cover, thereby increasing the contact distance with the medium and reducing the contact temperature between the packing and the medium.

[0015] According to some preferred implementation aspects of the utility model, a tail rod is provided at the bottom of the gate, and the lower end of the tail rod penetrates the valve body and extends downward. In the actual production process, the valve is under pressure, and the reverse extrusion force of the tail rod and the valve stem offsets each other, reducing the thrust and pull required by the actuator, and only a very low hydraulic pressure is needed to open / close the valve.

[0016] According to some preferred implementation aspects of the utility model, a lower valve cover is provided below the valve body, the lower valve cover includes a lower flange and a second extension portion extending downward from the lower flange, the bottom end of the tail rod passes through the bottom surface of the second extension portion and extends downward, and a second sealing assembly and a second packing gland are provided between the tail rod and the second extension portion. The structure of the second sealing assembly is basically the same as that of the first sealing assembly, and also includes an upper packing, a middle packing and a lower packing, the upper packing and / or the lower packing includes a lip seal ring or a plurality of lip seal rings stacked up and down, and the middle packing is graphite.

[0017] According to some preferred implementation aspects of the utility model, the top surface of the upper packing of the second sealing assembly is lower than the bottom surface of the lower flange. Preferably, the top surface of the upper packing of the second sealing assembly is lower than half of the overall height of the lower valve cover.

[0018] According to some preferred implementation aspects of the utility model, the second packing gland extends downward to the outside of the second extension portion, a sliding groove is provided on the second packing gland, a limiting member is provided on the side of the tail rod, and the limiting member is accommodated in the sliding groove to guide and limit the movement of the valve stem, the gate plate and the tail rod.

[0019] According to some preferred implementation aspects of the utility model, the gate includes a large leaf and a small leaf that cooperate with each other, the large leaf includes a main body, an upper clamping part extending upward from the main body and / or a lower clamping part extending downward from the main body, the bottom of the valve stem is clamped and floatingly connected with the upper clamping part; and / or the top of the tail rod is clamped and floatingly connected with the lower clamping part. Specifically, the upper clamping part or the lower clamping part has a first clamping block and a first clamping groove, the bottom of the valve stem or the top of the tail rod has a second clamping block, the first clamping groove is formed by two first clamping blocks, and the second clamping block is clamped in the first clamping groove to achieve clamping. That is, a T-head is used to connect the large leaf to the bottom of the valve stem and / or the top of the tail rod, the depth of the first clamping groove is greater than the height of the second clamping block, and an adjustable gap can be achieved in the sealing of the gate and the valve seat. The details are as follows:

[0020] The large leaf and the small leaf are connected by a bow spring and a clamping piece. The depth of the first clamping groove is greater than the height of the second clamping block. Preferably, the depth of the first clamping groove is 0.3-1mm greater than the height of the second clamping block, preferably 0.4-0.6mm, so that the large leaf can float and when the medium passes through the gate plate, the large leaf and the small leaf are stretched toward the valve seats on both sides and sealed with the valve seats.

[0021] According to some preferred implementation aspects of the present invention, the length of the leaflet is greater than the length of the large leaflet body, the top width of the leaflet is greater than the chord length of the corresponding position of the bottom surface of the cover body so that the top of the leaflet contacts the bottom surface of the cover body to achieve the upper limit of the gate movement, and the bottom width of the leaflet is greater than the chord length of the corresponding position of the bottom surface of the cavity so that the bottom of the leaflet contacts the bottom surface of the cavity to achieve the lower limit of the gate movement.

[0022] Preferably, a guide plate for guiding the movement of the gate plate is provided on the valve seat.

[0023] Due to the adoption of the above technical scheme, compared with the prior art, the gate valve of the utility model suitable for geothermal wellhead realizes hydraulic control of the valve stem by adopting a hydraulic drive mechanism, and then controls the opening and closing of the gate plate by hydraulic pressure, and there is a metal seal between the valve seat and the valve body, which has a good sealing effect at high temperature and avoids high-temperature seal failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 This is a schematic diagram of the three-dimensional structure of the gate valve in the preferred embodiment of the utility model;

[0026] Figure 2 This is a schematic diagram of the cross-sectional structure of a gate valve in a preferred embodiment of the utility model;

[0027] Figure 3 for Figure 2 Enlarged view of the middle I part;

[0028] Figure 4 for Figure 2 Enlarged view of middle part II;

[0029] Figure 5 for Figure 2 Enlarged view of middle part III;

[0030] Figure 6 This is a schematic diagram of the three-dimensional structure of the gate, valve stem, tail rod, valve seat, and guide plate in the preferred embodiment of the utility model;

[0031] Figure 7 This is a schematic diagram of the three-dimensional structure of the gate, valve stem and tail rod connected in the preferred embodiment of the utility model;

[0032] Figure 8 This is a schematic diagram of the three-dimensional structure of the gate in the preferred embodiment of the utility model;

[0033] Fig. 9 This is a schematic diagram of the cross-sectional structure of the gate in the preferred embodiment of the utility model;

[0034] The reference numerals are as follows:

[0035]

[0036] DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0038] like Figure 1-9 As shown, the gate valve suitable for geothermal wellhead in this embodiment includes a valve body 9, an upper valve cover 12, a lower valve cover, a pressure cover 17, a pressure rod 23, a hydraulic drive mechanism, a valve stem 29 arranged through the upper valve cover 12, a tail rod 2 arranged through the lower valve cover, a gate plate 31 arranged at the lower end of the valve stem 29, a valve seat 8 and a guide plate 61 arranged in the valve body 9, and the pressure rod 23 is arranged in the pressure cover 17 to limit the upper limit position of the valve stem 29 moving upward. The valve stem 29 is used to drive the gate plate 31 to move to realize the opening and closing of the gate valve. There is a cavity between the valve body 9 and the upper valve cover 12, and the gate plate 31 and the valve seat 8 are accommodated in the cavity. A hydraulic drive mechanism is arranged above the upper valve cover 12, and the upper end of the valve stem 29 extends upward into the hydraulic drive mechanism. The upper valve cover 12 and the lower valve cover are arranged above and below the valve body 9 respectively, and the hydraulic drive mechanism is arranged between the pressure cover 17 and the upper valve cover 12. The upper end of the gate plate 31 is connected to the bottom of the valve stem 29, the lower end of the gate plate 31 is connected to the top of the tail rod 2, and the guide plate 61 is fixed to the valve seat 8 to guide the movement of the gate plate 31. Seals are provided between the valve stem 29 and the valve cover, and between the tail rod 2 and the lower valve cover, namely the first sealing assembly and the second sealing assembly. At the same time, the valve is opened and closed by a metal surface seal, and the sealing surface between the gate plate 31 and the valve seat 8 is treated with carbide spraying, and the surface roughness reaches Ra0.1, which can effectively achieve sealing. At the same time, there is no need to worry about sealing failure in a high temperature environment, that is, the gate valve in this embodiment, there is no non-metallic sealing ring between the valve seat 8 and the valve body 9, etc., which is suitable for a high temperature environment of 345°C, and there is no need to worry about sealing failure, which can maximize the service life and reduce maintenance costs.

[0039] The following introduces the structure and connection relationship of some components:

[0040] The upper valve cover 12 includes a cover body 48, a first extension portion 49 and an upper flange 50 from bottom to top. The cover body 48 is connected to the valve body 9. The first extension portion 49 extends upward from the cover body 48. The upper flange 50 is arranged on the top of the first extension portion 49. The upper flange 50 is connected to the hydraulic drive mechanism.

[0041] A first sealing assembly is provided between the valve stem 29 and the first extension 49, and a first packing gland 39 is provided between the valve stem 29 and the first extension 49 and the upper flange 50, for pressing the first sealing assembly. The first sealing assembly includes an upper packing 41, a middle packing 35 and a lower packing 36 in sequence, and the upper packing 41 and the lower packing 36 include a lip seal ring or a plurality of lip seal rings stacked up and down, and the cross section of the lip seal ring is U-shaped or V-shaped, and the opening of the U-shaped or V-shaped is downward (toward the valve seat) when in use. There is a gap between the upper packing 41 and the lower packing 36, and an injection valve 33 for injecting the middle packing 35 into the gap is provided on the first extension 49 corresponding to the gap between the upper packing 41 and the lower packing 36, and the middle packing 35 is preferably graphite.

[0042] In this embodiment, the bottom surface of the lower packing 36 of the first sealing assembly is higher than the top surface of the cover body 48. Preferably, the bottom surface of the lower packing 36 is higher than half of the overall height of the upper valve cover 12. The contact distance with the medium is increased to reduce the contact temperature between the packing and the medium.

[0043] The hydraulic drive mechanism includes a cylinder 11 and a piston 15. The cylinder 11 is located between the gland 17 and the upper flange 50. A moving cavity for the piston 15 to move is formed between the cylinder 11, the gland 17 and the upper flange 50. The piston 15 is sleeved and fixed on the upper end of the valve stem 29. The piston 15 is used to divide the moving cavity into an upper moving cavity 43 and a lower moving cavity 44. The cylinder 11 is provided with a first connecting hole 26 and a second connecting hole 27 corresponding to the upper moving cavity 43 and the lower moving cavity 44, respectively. The first connecting hole 26 and the second connecting hole 27 penetrate the wall thickness direction of the cylinder 11. The first connecting hole 26 and the second connecting hole 27 are connected to the hydraulic station to inject hydraulic medium into the upper moving cavity 43 or the lower moving cavity 44 to drive the piston 15 to move, thereby realizing the movement of the valve stem 29. The valve opening / closing is controlled by the hydraulic drive mechanism (double-acting hydraulic actuator), which reduces labor costs; the actuator opening / closing is remotely controlled to improve work efficiency.

[0044] A first annular groove 45 with an increased inner diameter is provided on the inner wall of the upper movement cavity 43 corresponding to the first communication hole 26; a second annular groove 46 with an increased inner diameter is provided on the inner wall of the lower movement cavity 44 corresponding to the second communication hole 27. The first communication hole 26 and the corresponding first annular groove 45, the second communication hole 27 and the corresponding second annular groove 46 are respectively arranged at the top and bottom of the movement cavity to avoid the problem of excessively large driving pressure caused by excessively fitting the top of the piston 15 to the bottom surface of the gland 17, the bottom of the piston 15 to the top surface of the upper flange 50 or to the communication hole.

[0045] The top of the first packing gland 39 is higher than the top of the upper flange 50 and extends into the motion cavity; a notch 47 is provided on the outer edge of the top of the piston 15 to prevent the piston 15 from being in close contact with the bottom surface of the gland 17, the top surface of the upper flange 50, and the connecting hole, resulting in excessive oil injection resistance. The provision of the annular groove and the notch 47 and the extension and protrusion of the top of the first packing gland 39 can effectively prevent the water hammer phenomenon of the injected hydraulic oil, reduce the impact effect of the hydraulic oil itself, and effectively reduce the movement error.

[0046] The hydraulic drive mechanism in this embodiment drives the valve to open / close in the following working principle: when the valve is opened, the hydraulic actuator moves downward through the second connecting hole 27 to inject oil into the cavity 44, driving the valve stem 29 to move upward, and the large leaf 54 of the gate 31 drives the small leaf 55 of the gate 31 to move upward until the small leaf 55 abuts against the valve cover, the gate 31 cannot move, and the valve is opened. When the valve is closed, the hydraulic actuator moves upward through the first connecting hole 26 to inject oil into the cavity 43, pushing the piston 15 to drive the valve stem 29 to move downward, and the bottom of the valve stem 29 abuts against the large leaf 54 of the gate 31 and moves downward. Because the large and small leaves 55 are connected by the wedging surface and the elastic member, the large leaf 54 moves downward while driving the small leaf 55 downward until the small leaf 55 abuts against the bottom surface of the valve body 9, and the valve is closed.

[0047] The tail rod 2 extends downward from the bottom of the gate plate 31 and penetrates the bottom of the valve body 9 and the lower valve cover below the valve body 9. The lower valve cover includes a lower flange 5 and a second extension portion 51 extending downward from the lower flange 5. The bottom end of the tail rod 2 penetrates the bottom surface of the second extension portion 51 and extends downward. In the actual production process, the valve is under pressure, and the reverse extrusion force of the tail rod 2 and the valve stem 29 offsets each other, reducing the thrust or pull required by the hydraulic actuator, and only a very low hydraulic pressure is required to open / close the valve.

[0048] A second sealing assembly and a second packing gland 1 are provided between the tail rod 2 and the second extension portion 51. The structure of the second sealing assembly is basically the same as that of the first sealing assembly, and also includes an upper packing 41, a middle packing 35 and a lower packing 36 in sequence. The upper packing 41 and the lower packing 36 include a lip seal ring or a plurality of lip seal rings stacked up and down. When in use, the U-shaped or V-shaped opening faces upward (toward the valve seat), and the middle packing 35 is graphite.

[0049] At the same time, similar to the first sealing assembly, the top surface of the upper packing 41 of the second sealing assembly is lower than the bottom surface of the lower flange 5. Preferably, the top surface of the upper packing 41 of the second sealing assembly is lower than half of the overall height of the lower valve cover, thereby increasing the contact distance with the medium and reducing the contact temperature between the packing and the medium.

[0050] The upper and lower packings of the sealing assembly realize double sealing. An injection valve 33 is installed in the middle of the packing. In the actual production process, sealing filling materials such as graphite and / or grease can be injected at any time to strengthen the sealing of the packing at the valve stem 29 to avoid the upper and lower packings 36 from failing to work normally due to excessive medium temperature.

[0051] The second packing gland 1 extends downward to the outside of the second extension portion 51, and a sliding groove 52 is provided on the second packing gland 1. A limiting member 533 is provided on the side of the tail rod 2, and the limiting member 533 is accommodated in the sliding groove 52 to guide and limit the movement of the valve stem 29, the gate plate 31 and the tail rod 2.

[0052] The gate plate 31 includes a large leaflet 54 and a small leaflet 55 that cooperate with each other. The large leaflet 54 and the small leaflet 55 are in contact with each other through a V-shaped inclined surface. The large leaflet 54 includes a main body, an upper clamping part extending upward from the main body, and a lower clamping part extending downward from the main body. The bottom of the valve stem 29 is clamped and floatingly connected with the upper clamping part; the top of the tail rod 2 is clamped and floatingly connected with the lower clamping part.

[0053] Specifically, the upper engaging part or the lower engaging part has a first engaging block 57 and a first engaging groove 58, the first engaging groove 58 is formed by two first engaging blocks 57, the bottom of the valve stem 29 has a second engaging block 59, the top of the tail rod 2 has a second engaging block 59 and a second engaging groove, the first engaging block 57 is engaged in the second engaging groove, and the second engaging block 59 is engaged in the first engaging groove 58 to achieve engagement. That is, the large leaf 54 is connected to the bottom of the valve stem 29 and the top of the tail rod 2 by a T-shaped head, and the depth of the first engaging groove 58 is greater than the height of the second engaging block 59 to achieve floating connection, so as to achieve an adjustable gap between the gate plate 31 and the valve seat 8.

[0054] The details are as follows: the large leaf 54 and the small leaf 55 are connected by a bow spring 56 and a clamping piece 62 such as a screw or a rivet, the depth of the first clamping groove 58 is greater than the height of the second clamping block 59, and preferably the depth of the first clamping groove 58 is 0.3-1mm greater than the height of the second clamping block 59, preferably 0.4-0.6mm, so that the large leaf 54 can float left and right, and when the medium passes through the gate plate 31, the large leaf 54 and the small leaf 55 are stretched to the valve seats 8 on both sides and achieve a mating seal with the valve seats 8, and a metal mating seal is achieved between the valve seats 8 and the valve body 9.

[0055] The size of the connection between the main body of the large leaf 54 and the upper and lower engaging parts is reduced, the length of the small leaf 55 is greater than the length of the main body of the large leaf 54, the top width of the small leaf 55 is greater than the chord length of the corresponding position of the bottom surface of the cover body 48 so that the top of the small leaf 55 contacts the bottom surface of the cover body 48 to achieve the upper limit of the movement of the gate 31, and the bottom width of the small leaf 55 is greater than the chord length of the corresponding position of the bottom surface of the cavity so that the bottom of the small leaf 55 contacts the bottom surface of the cavity to achieve the lower limit of the movement of the gate 31. That is, in this application, the small leaf 55 of the gate 31 contacts the upper valve cover 12 to achieve the upper limit of the movement of the gate, and the small leaf 55 contacts the bottom of the cavity of the valve body 9 to achieve the lower limit of the movement of the gate.

[0056] The connection and action principle between the gate 31 and the valve stem 29 and the tail rod 2 in this embodiment are as follows: the gate 31 is divided into a large leaf 54 and a small leaf 55, which are assembled together by two bow springs 56. The valve seat 8 and the valve body 9, and the valve seat 8 and the gate 31 are all metal-to-metal contact. The gate 31 and the valve stem 29 and the tail rod 2 are connected by a T-head, and the gate 31 and the valve stem 29 are in surface contact. The gate 31 can be flexibly fine-tuned in the cavity of the valve body 9, avoiding the limitation of the threads of the valve stem 29 and the tail rod 2, and the small activity space cannot be adjusted. And when the threaded connection is used, the valve cover and the valve stem 29, the gate 31 and the valve stem 29 or the tail rod 2, and the lower valve cover and the tail rod 2 have high coaxiality requirements and high processing costs. And when the upstream pressure of the valve pushes the gate 31 to press the downstream valve seat 8, the connection structure of the T-head can make the gate 31 more easily pushed onto the downstream valve seat 8.

[0057] The gate valve in this embodiment also includes multiple retaining rings (18, 24, 38, 40), O-rings (14, 16, 22, 37) for sealing, sealing rings (6, 10), nuts (4, 20, 25, 30) and studs (13, 28, 32) for connection, etc., which will not be repeated here.

[0058] The geothermal metal-sealed double-acting hydraulic gate valve in this embodiment has the following structural features:

[0059] 1. Sealing between the valve stem 29 and the upper and lower valve covers: In order to be suitable for use in high-temperature environments, the sealing method between the valve stem 29 and the valve cover adopts three types of packing seals: upper, middle and lower. In addition to the upper and lower multi-lip high-temperature sealing rings, space is reserved between the upper and lower packings 36, and graphite and grease injection seals are used to achieve multiple seals to ensure effective sealing during the actual use of the valve.

[0060] 2. Connection method between gate 31, valve stem 29 and tail rod 2: A connection method different from conventional threaded connection is adopted, which is a T-head connection. The movable space between gate 31 and valve stem 29 is not limited. The large and small leaves 55 of gate 31 are used in conjunction with the bow spring 56 and the metal seal of valve seat 8. When the upstream pressure of the valve pushes gate 31 to move downstream, the T-head connection method allows gate 31 to have enough space to move, without the space being limited due to the consideration of the threaded connection between valve stem 29 and gate 31. When the threaded connection is made, the thread of valve stem 29 receives the force, which reduces the service life of the valve.

[0061] 3. Valve driving method: The valve is driven by a double-acting hydraulic actuator. There is no need to manually operate the handwheel to control the opening and closing of the valve. The valve itself has a tail rod 2 design, which reduces the operating torque. At the same time, the customer can remotely control the pressure of the double-acting hydraulic actuator on site to easily open and close the valve.

[0062] The 345°C high temperature geothermal double acting hydraulic gate valve in this embodiment has the following advantages:

[0063] 1. The on-site hydraulic station is connected to the two oil filling ports (connecting holes) of the actuator. The on / off valve controls the two oil ports to pressurize the hydraulic oil to push the piston 15 up and down; it reduces labor, improves efficiency, and enables remote control of the valve: Compared with the manual gate valve, a double-acting hydraulic actuator is used to remotely control the hydraulic station to pressurize the valve to open / close it. At the same time, a displacement sensor device can be added at the tail rod 2 to provide real-time feedback on the valve status of the central control platform, reducing labor costs and improving production efficiency.

[0064] 2. The geothermal gate valve uses a complete metal seal between the gate 31 and the valve seat 8, without using a soft seal. In a 345°C high temperature medium, the metal seal is more reliable and reduces seal failure. When the medium enters the gate, the large and small leaves move in opposite directions, fit against the valve seat and push the valve seat to fit against the valve body.

[0065] 3. With tail rod 2, during the production process, the valve is under pressure, and the reverse extrusion forces of tail rod 2 and valve stem 29 offset each other, reducing the thrust and pull required by the actuator, and only very low hydraulic pressure is needed to open / close the valve.

[0066] 4. The valve stem 29 and the tail rod 2 are connected to the gate plate 31 by a T-shaped head floating connection, which is easy to assemble. During use, there is an adjustable gap between the gate plate 31 and the valve stem 29 to achieve the sealing of the gate plate 31 and the valve seat 8.

[0067] 5. The packing position of the valve stem 29 and the tail rod 2 takes into account the medium temperature, increases the contact distance with the medium, and reduces the contact temperature between the packing and the medium. At the same time, in order to meet the sealing requirements under high temperature, multiple groups of packings are used at the top, middle and bottom to complete multiple sealing.

[0068] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with this technology to understand the content of the utility model and implement it accordingly. They cannot be used to limit the protection scope of the utility model. All equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A gate valve suitable for geothermal wellhead, comprising a gland, a valve body, an upper valve cover, a valve stem penetrating the upper valve cover, a gate plate arranged at the lower end of the valve stem, and a valve seat arranged in the valve body, wherein the gland is located above the upper valve cover, the valve stem is used to drive the gate plate to move to realize the opening and closing of the gate valve, a cavity is provided between the valve body and the upper valve cover, the gate plate and the valve seat are accommodated in the cavity, and the characteristics are: A hydraulic drive mechanism is arranged above the upper valve cover, and the upper end of the valve stem extends upward into the hydraulic drive mechanism, and the hydraulic drive mechanism includes a cylinder and a piston. The top of the upper valve cover is provided with an upper flange, and the cylinder is located between the pressure cover and the upper flange, and a motion cavity for the piston to move is formed between the cylinder, the pressure cover and the upper flange, and the piston is sleeved and fixed on the upper end of the valve stem, and the piston is used to divide the motion cavity into an upper motion cavity and a lower motion cavity, and the cylinder is respectively provided with a first connecting hole and a second connecting hole corresponding to the upper motion cavity and the lower motion cavity, and the first connecting hole and the second connecting hole penetrate the wall thickness direction of the cylinder, and the first connecting hole and the second connecting hole are connected with the hydraulic station for injecting hydraulic medium into the upper motion cavity or the lower motion cavity to drive the piston to move, so as to realize the vertical movement of the gate plate; there is a metal seal between the valve seat and the valve body.

2. The gate valve according to claim 1, characterized in that: A first annular groove is provided on the inner wall of the upper movement cavity corresponding to the first communicating hole; and / or a second annular groove is provided on the inner wall of the lower movement cavity corresponding to the second communicating hole.

3. The gate valve according to claim 1, characterized in that: The upper valve cover includes a cover body and a first extension portion extending upward from the cover body, the upper flange is arranged on the top of the first extension portion, a first sealing assembly is arranged between the valve stem and the first extension portion, the first sealing assembly includes an upper packing and a lower packing, and the upper packing and / or the lower packing includes a lip sealing ring or a plurality of lip sealing rings stacked up and down.

4. The gate valve according to claim 3, characterized in that: There is a gap between the upper filler and the lower filler, and an injection valve for injecting a middle filler into the gap is arranged on the first extension portion corresponding to the gap between the upper filler and the lower filler.

5. The gate valve according to claim 3, characterized in that: The bottom surface of the lower filler is higher than the top surface of the cover body.

6. The gate valve according to claim 3, characterized in that: A tail rod is arranged at the bottom of the gate plate, and the lower end of the tail rod penetrates the valve body and extends downward.

7. The gate valve according to claim 6, characterized in that: A lower valve cover is arranged below the valve body, and the lower valve cover includes a lower flange and a second extension portion extending downward from the lower flange. The bottom end of the tail rod passes through the bottom surface of the second extension portion and extends downward. A second sealing assembly and a second packing gland are arranged between the tail rod and the second extension portion, and the top surface of the second sealing assembly is lower than the bottom surface of the lower flange.

8. The gate valve according to claim 7, characterized in that: The second stuffing gland extends downward to the outside of the second extension portion, a sliding groove is provided on the second stuffing gland, a limiting piece is provided on the side of the tail rod, and the limiting piece is accommodated in the sliding groove.

9. The gate valve according to claim 6, characterized in that: The gate plate includes a large leaf and a small leaf that cooperate with each other, the large leaf includes a main body, an upper clamping part extending upward from the main body and / or a lower clamping part extending downward from the main body, the bottom of the valve stem is floatingly connected to the upper clamping part; and / or the top end of the tail rod is floatingly connected to the lower clamping part.

10. The gate valve according to claim 9, characterized in that: The length of the leaflet is greater than the length of the main leaflet, the top width of the leaflet is greater than the chord length of the corresponding position of the bottom surface of the cover body, and the bottom width of the leaflet is greater than the chord length of the corresponding position of the bottom surface of the cavity.

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