Pneumatic low-temperature gate valve

Abstract

The utility model relates to the technical field of valves, in particular to a pneumatic low-temperature gate valve which comprises a valve body, a valve cover, a gate plate, a valve rod and an executing mechanism, a cavity is formed in the valve body, the valve cover is installed at the top of the valve body, the gate plate is arranged in the valve body, two valve seats matched with the gate plate in a sealing mode are further arranged in the valve body, and the two valve seats are located on the two sides of the gate plate respectively. One end of the valve rod is connected with the flashboard, the other end of the valve rod penetrates through the valve deck to be connected with the executing mechanism, the executing mechanism drives the valve rod and the flashboard to reciprocate, the flashboard controls communication or blocking of the cavity, and the cavity is divided into an inlet cavity, a middle cavity and an outlet cavity through sealing fit of the flashboard and the two valve seats. The pressure equalizing holes are formed in the gate plate, so that the pressure of the middle cavity in the valve body and the pressure of the inlet cavity are kept balanced all the time, the pressure of the middle cavity cannot be increased sharply, and then potential risks cannot be caused.

Description

Technical Field

[0001] The utility model relates to the technical field of valves, in particular to a pneumatic low-temperature gate valve. Background Art

[0002] Gate valves are the most important type of valves at present, and are widely used in the circulation and cutoff of liquids, gases, dust and other media.

[0003] In LNG, LN2, LO2 and other low-temperature medium pipelines and devices, gate valves suitable for various low-temperature conditions must be used in large quantities. However, low-temperature media have potential dangerous factors such as strong temperature sensitivity, easy expansion, and easy leakage. For the gate valve of the linear stroke switch, on the one hand, it is difficult to ensure the fit between the rigid gate and the valve seat, so the reliability of the sealing performance is insufficient. On the other hand, once the gate and the valve seats on both ends are tightly sealed, the pressure of the low-temperature medium in the middle cavity is difficult to release. Once the temperature of the pipeline rises, the volume of the low-temperature medium will increase sharply (such as liquefied natural gas will increase by 600 times). The failure to discharge the pressure in the middle cavity of the valve body will cause great danger, and the process of the valve stem lifting upward is also very likely to cause leakage of the low-temperature medium. Once leakage occurs, the low-temperature medium will produce a heating process after contacting with the normal temperature environment due to the large temperature difference. The low-temperature medium will be gasified during the heating. At this time, the volume of the medium will also expand hundreds of times, resulting in a sharp release of the leakage point, and even causing the consequences of fire and explosion, which will cause great hidden dangers and potential hazards to the on-site operators and devices.

[0004] To this end, users, design institutes and manufacturers have come up with a variety of solutions for improvement, including improving packing, enlarging actuators, using higher-quality sealing materials, etc. Although these applications have alleviated internal leakage, external leakage and operational safety, external leakage and operational safety still exist, and the problem cannot be fundamentally solved. Utility Model Content

[0005] The purpose of the utility model is to overcome the shortcomings and deficiencies of the prior art and to provide a pneumatic low-temperature gate valve. The utility model provides a pressure equalizing hole on the gate plate so that the pressure of the middle cavity inside the valve body is always balanced with the pressure of the inlet cavity, which will not cause a sharp increase in the pressure of the middle cavity and thus will not cause any hidden dangers.

[0006] The technical scheme adopted by the utility model is as follows: a pneumatic low-temperature gate valve, including a valve body, a valve cover, a gate, a valve stem and an actuator, a chamber is opened in the valve body, the valve cover is installed on the top of the valve body, the gate is arranged in the valve body, and two valve seats which are sealed with the gate are also arranged in the valve body, the two valve seats are respectively located on both sides of the gate, one end of the valve stem is connected with the gate and the other end passes through the valve cover and is connected with the actuator, the actuator drives the valve stem and the gate to reciprocate, and the gate controls the connection or blocking of the chamber, the chamber is divided into an inlet chamber, a middle chamber and an outlet chamber by the sealing cooperation between the gate and the two valve seats, and a pressure equalizing hole is also opened on the gate, and when the gate is sealed with the two valve seats, the pressure equalizing hole connects the inlet chamber and the middle chamber.

[0007] The sealing surfaces of the gate plate and the two valve seats are all inclined sealing slopes, and the sealing slopes form an inclination angle of 2° to 5° with the axis of the valve stem.

[0008] The gate plate is symmetrically arranged along the axis of the valve stem, an end of the gate plate close to the valve stem is recessed with an inverted mushroom-shaped groove, and an end of the gate plate away from the valve stem is recessed with an inverted U-shaped groove.

[0009] The actuator is a pneumatic actuator, which includes a cylinder, a piston and an indicator rod. The piston is reciprocatingly slidably arranged in the cylinder. The valve stem and the indicator rod extend from both ends of the cylinder to the inside of the cylinder and are connected to the piston respectively. A valve position indicating device is also installed on the cylinder. The end of the indicator rod away from the piston extends to the outside of the cylinder and is connected to a connecting block. The valve position indicating device is connected to the connecting block through a fork. When the piston drives the indicator rod to move, the connecting block drives the fork to move. The valve position indicating device indicates the position of the gate through the position of the fork.

[0010] The valve stem is threadedly connected to the piston, and the threaded connection between the valve stem and the piston is also filled with thread glue. The valve stem is provided with a first conical surface, and the piston is provided with a second conical surface matched with the first conical surface. The valve stem is made of stainless steel metal, and the piston is made of aluminum alloy. The first conical surface of the valve stem is sealed with the second conical surface of the piston, and an O-ring is also provided between the valve stem and the piston.

[0011] A scraper-type sealing ring is provided between the valve stem and the cylinder. The scraper-type sealing ring includes a non-metallic elastic ring and two metal elastic elements arranged on the same side of the non-metallic elastic ring. There is a gap between the two metal elastic elements, and the two metal elastic elements are respectively pressed against the cylinder and the valve stem. A scraper-shaped groove is provided on the side where the non-metallic elastic ring is in contact with the valve stem. A scraper-type sealing ring is also provided between the indicator rod and the cylinder.

[0012] It also includes a packing gland and a packing assembly, wherein the packing gland is connected to the valve cover by bolts, and the packing assembly is crimped between the valve cover and the valve stem by the packing gland. The packing assembly includes a lip seal ring, a metal retaining ring, a lower packing combination, a spacer ring, an upper packing combination and a packing sleeve, which are arranged in sequence from bottom to top, and one side of the lip seal ring is tightly against the valve stem and the other side is tightly against the valve cover.

[0013] The beneficial effects of the utility model are as follows: the utility model provides a pressure equalizing hole on the gate plate. When the gate plate and the valve seat are sealed together, that is, when the gate valve is closed, the pressure equalizing hole can also connect the inlet cavity and the middle cavity, so that the pressure of the middle cavity inside the valve body is always balanced with the pressure of the inlet cavity, which will not cause a sharp increase in the pressure in the middle cavity, thereby preventing dangerous hazards, and is more suitable for pipelines and devices for low-temperature media. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the utility model.

[0015] Figure 1 This is a schematic diagram of the structure of a pneumatic low-temperature gate valve of the utility model;

[0016] Figure 2 for Figure 1 A local enlarged schematic diagram of the middle A;

[0017] Figure 3 This is a schematic diagram of the structure of the gate plate in the utility model;

[0018] Figure 4 for Figure 1 A partial enlarged schematic diagram of point B in the middle;

[0019] Figure 5 for Figure 1 A partial enlarged schematic diagram of point C in the middle;

[0020] Figure 6 for Figure 1 A partial enlarged schematic diagram of point D in the middle;

[0021] Figure 7 for Figure 1 A partial enlarged schematic diagram of point E in the middle;

[0022] In the figure, 1-valve body, 2-valve cover, 3-gate, 4-valve stem, 5-actuator, 6-valve seat, 7-inlet chamber, 8-middle chamber, 9-outlet chamber, 10-pressure equalizing hole, 11-sealing slope, 12-inclination angle, 13-inverted mushroom-shaped groove, 14-inverted U-shaped groove, 15-cylinder, 16-piston, 17-indicator rod, 18-valve position indicating device, 19-connecting block, 20-shift fork, 21-first cone surface, 22-second cone surface, 23-O-type sealing ring, 24-non-metallic elastic ring, 25-metal elastic element, 26-scraper-shaped groove, 27-packing gland, 28-lip sealing ring, 29-metal retaining ring, 30-lower packing combination, 31-spacer ring, 32-upper packing combination, 33-packing sleeve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the utility model clearer, the utility model will be further described in detail below with reference to the accompanying drawings.

[0024] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0025] The directions and positions mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inside", "outside", "top", "bottom", "side", etc., are only for reference to the directions or positions of the drawings. Therefore, the directions and positions used are used to explain and understand the present invention, but not to limit the scope of protection of the present invention.

[0026] like Figures 1 to 7 The figure shows an embodiment of the utility model, a pneumatic low-temperature gate valve, comprising a valve body 1, a valve cover 2, a gate plate 3, a valve stem 4 and an actuator 5. A chamber is provided in the valve body 1, the valve cover 2 is installed on the top of the valve body 1, the gate plate 3 is arranged in the valve body 1, and two valve seats 6 that are sealed with the gate plate 3 are also provided in the valve body 1. The two valve seats 6 are respectively located on both sides of the gate plate 3, one end of the valve stem 4 is connected with the gate plate 3 and the other end passes through the valve cover 2 and is connected with the actuator 5, the actuator 5 drives the valve stem 4 and the gate plate 3 to reciprocate, and the gate plate 3 controls the connection or blocking of the chamber, the chamber is divided into an inlet chamber 7, a middle chamber 8 and an outlet chamber 9 by the gate plate 3 and the two valve seats 6 are sealed, and an equalizing hole 10 is also provided on the gate plate 3. When the gate plate 3 is sealed with the two valve seats 6, the equalizing hole 10 connects the inlet chamber 7 and the middle chamber 8.

[0027] The beneficial effects of such an arrangement are as follows: the utility model provides a pressure equalizing hole on the gate plate. When the gate plate and the valve seat are sealed together, that is, when the gate valve is closed, the pressure equalizing hole can also connect the inlet cavity and the middle cavity, so that the pressure of the middle cavity inside the valve body is always balanced with the pressure of the inlet cavity, which will not cause a sharp increase in the pressure in the middle cavity and thus will not cause any hidden dangers. The utility model is more suitable for pipelines and devices for low-temperature media.

[0028] It is further provided that the sealing surfaces of the gate plate 3 and the two valve seats 6 are both inclined sealing slopes 11 , and an inclination angle 12 of 2° to 5° is formed between the sealing slope 11 and the axis of the valve stem 4 .

[0029] The beneficial effects of such a setting are as follows: the sealing surface is set to be a bevel seal to ensure a good sealing effect. The specific setting angle of the inclination angle is adjusted accordingly according to the diameter of the gate valve. If the gate valve is of small diameter, the inclination angle is set to a larger angle.

[0030] It is further provided that the gate plate 3 is symmetrically arranged along the axis of the valve stem 4 , an inverted mushroom-shaped groove 13 is recessed at one end of the gate plate 3 close to the valve stem 4 , and an inverted U-shaped groove 14 is recessed at one end of the gate plate 3 away from the valve stem 4 .

[0031] The beneficial effects of this arrangement are as follows: through the symmetrical arrangement of the gate plate and the inverted mushroom-shaped grooves and inverted U-shaped grooves recessed at both ends, the thickness of the gate plate and the valve seat sealing fit on both sides is kept balanced. Such a structure has suitable elasticity, sufficient strength and uniformity of changes at low temperatures, ensuring the sealing performance at low temperatures.

[0032] It is further configured that the actuator 5 is a pneumatic actuator, which includes a cylinder 15, a piston 16 and an indicator rod 17. The piston 16 is reciprocatingly slidably arranged in the cylinder 15. The valve stem 4 and the indicator rod 17 extend from both ends of the cylinder 15 to the inside of the cylinder 15 and are connected to the piston 16. A valve position indicating device 18 is also installed on the cylinder 15. The end of the indicator rod 17 away from the piston 16 extends to the outside of the cylinder 15 and is connected to a connecting block 19. The valve position indicating device 18 is connected to the connecting block 19 through a fork 20. When the piston 16 drives the indicator rod 17 to move, the connecting block 19 drives the fork 20 to move. The valve position indicating device 18 indicates the position of the gate 3 through the position of the fork 20.

[0033] The beneficial effects of such a configuration are as follows: the piston is driven to slide back and forth by changing the air source pressure in the cylinder, and then the piston drives the valve stem and the gate plate to open and close the gate valve. When the piston slides upward, the gate valve opens, and vice versa, the piston slides downward until the driven gate plate is completely sealed with the valve seat and the gate valve closes. The pneumatic drive method is adopted to make the opening and closing of the gate valve both stable and responsive. An indicator rod is also connected to the other side of the piston. The movement of the piston will also drive the movement of the indicator rod. The indicator rod is connected to the valve position indicating device through a connecting block and a shift fork. The valve position indicating device adopts the existing technology, and the valve position indicating device can clearly indicate the specific switching position of the gate valve through the movement of the shift fork.

[0034] It is further configured that the valve stem 4 is threadedly connected to the piston 16, and the threaded connection between the valve stem 4 and the piston 16 is also filled with thread glue. The valve stem 4 is provided with a first conical surface 21, and the piston 16 is provided with a second conical surface 22 adapted to the first conical surface 21. The valve stem 4 is made of stainless steel metal, and the piston 16 is made of aluminum alloy. The first conical surface 21 of the valve stem 4 is sealed with the second conical surface 22 of the piston 16, and an O-ring 23 is also provided between the valve stem 4 and the piston 16.

[0035] The beneficial effects of such a configuration are as follows: secondary fixation is performed through thread glue to further improve the strength of the threaded connection, ensuring the long-term reliability of the connection and the seal; a combined sealing structure of a cone metal hard seal is formed by the first cone surface and the second cone surface, further helping to lock the valve stem and the piston; and the valve stem is made of stainless steel metal and the piston is made of aluminum alloy, and the sealing combination of the two has a suitable hardness difference, and the sealing is further increased by an O-ring. This structure has the advantage of better sealing performance.

[0036] It is further configured that a scraper-type sealing ring is provided between the valve stem 4 and the cylinder 15, and the scraper-type sealing ring includes a non-metallic elastic ring 24 and two metal elastic elements 25 arranged on the same side of the non-metallic elastic ring 24, there is a gap between the two metal elastic elements 25, and the two metal elastic elements 25 are respectively tightly against the cylinder 15 and the valve stem 4, a scraper-shaped groove 26 is provided on the side where the non-metallic elastic ring 24 is in contact with the valve stem 4, and a scraper-type sealing ring is also provided between the indicator rod 17 and the cylinder 15.

[0037] The beneficial effects of such a configuration are as follows: the scraper-type sealing ring can automatically clean the surface of the valve stem and the indicator rod when the valve stem and the indicator rod move up and down, preventing impurities and dust from invading the interior of the cylinder, thereby protecting the high purity of the cylinder chamber; the two metal elastic elements provide support so that the scraper-shaped groove is close to the surface of the valve stem or the indicator rod, thereby ensuring a good cleaning effect.

[0038] Further configuration includes a packing gland 27 and a packing assembly, wherein the packing gland 27 is connected to the valve cover 2 by bolts, and the packing assembly is crimped between the valve cover 2 and the valve stem 4 by the packing gland 27, and the packing assembly includes a lip seal 28, a metal retaining ring 29, a lower packing combination 30, a spacer ring 31, an upper packing combination 32 and a packing sleeve 33, which are arranged in sequence from bottom to top, and one side of the lip seal 28 is tightly against the valve stem 4 and the other side is tightly against the valve cover 2.

[0039] The beneficial effects of such a configuration are as follows: the bolts and nuts of the prior art are used for the bolt parts to lock the packing gland onto the valve cover; the valve stem and the valve cover are sealed by a double combination of a lip seal and a packing, which greatly improves the sealing performance and prevents the low-temperature medium from leaking out as the valve stem rises; the lip seal is an inverted V-shaped structure, in which a metal elastic ring is slightly opened in the middle to form an initial sealing force, so that the non-metallic rings on both sides of the lip seal fit tightly against the valve stem and the inner wall of the valve cover; the higher the pressure in the internal chamber of the valve, the better the sealing performance of the lip seal; this double combination seal ensures the absolute safety of the valve stem seal.

[0040] In summary, the following is the principle of the utility model. When the valve is normally opened, the air source pressure drives the piston to move upward, and the piston drives the valve stem to drive the gate upward to open the valve. If the valve needs to be closed, the air source pressure drives the piston to move downward, and the piston drives the valve stem to drive the gate downward until the gate and the valve seat sealing surface fit tightly together to close the valve. When the valve is closed, a pressure equalizing hole is set on the gate plate to connect the inlet cavity with the middle cavity, and the pressure in the middle cavity will not expand sharply due to temperature changes. The gate plate is provided with a force-balanced elastic structure and an appropriate inclination angle, which has a better wedging force with the valve seat sealing surface, so that better sealing performance can be obtained. The valve stem has a lip seal and a combination of multiple graphite packings for sealing protection, which prevents the leakage of low-temperature media, thereby ensuring the long-term reliable and safe application of pneumatic gate valves under low-temperature media.

[0041] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope covered by the present invention.

Claims

1. A pneumatic low-temperature gate valve, comprising a valve body (1), a valve cover (2), a gate plate (3), a valve stem (4) and an actuator (5), wherein a chamber is provided in the valve body (1), the valve cover (2) is mounted on the top of the valve body (1), the gate plate (3) is arranged in the valve body (1), and two valve seats (6) which are sealed with the gate plate (3) are also arranged in the valve body (1), the two valve seats (6) are respectively located on both sides of the gate plate (3), one end of the valve stem (4) is connected to the gate plate (3) and the other end passes through the valve cover (2) and is connected to the actuator (5), the actuator (5) drives the valve stem (4) and the gate plate (3) to reciprocate, and the gate plate (3) controls the connection or blocking of the chamber, characterized in that: The chamber is divided into an inlet chamber (7), a middle chamber (8) and an outlet chamber (9) by a gate plate (3) in sealing cooperation with two valve seats (6); a pressure equalizing hole (10) is also provided on the gate plate (3); when the gate plate (3) is in sealing cooperation with the two valve seats (6), the pressure equalizing hole (10) communicates with the inlet chamber (7) and the middle chamber (8).

2. A pneumatic cryogenic gate valve according to claim 1, characterized in that: The sealing surfaces of the gate plate (3) and the two valve seats (6) are both inclined sealing slopes (11), and an inclination angle (12) of 2° to 5° is formed between the sealing slope (11) and the axis of the valve stem (4).

3. A pneumatic cryogenic gate valve according to claim 1, characterized in that: The gate plate (3) is symmetrically arranged along the axis of the valve stem (4); an end of the gate plate (3) close to the valve stem (4) is recessed with an inverted mushroom-shaped groove (13), and an end of the gate plate (3) away from the valve stem (4) is recessed with an inverted U-shaped groove (14).

4. The pneumatic cryogenic gate valve according to claim 1, characterized in that: The actuator (5) is a pneumatic actuator, comprising a cylinder (15), a piston (16) and an indicator rod (17); the piston (16) is reciprocatingly slidably arranged in the cylinder (15); the valve rod (4) and the indicator rod (17) respectively extend from both ends of the cylinder (15) to the inside of the cylinder (15) and are connected to the piston (16); a valve position indicator device (18) is also installed on the cylinder (15); an end of the indicator rod (17) away from the piston (16) extends to the outside of the cylinder (15) and is connected to a connecting block (19); the valve position indicator device (18) is connected to the connecting block (19) via a shift fork (20); when the piston (16) drives the indicator rod (17) to move, the connecting block (19) drives the shift fork (20) to move; the valve position indicator device (18) indicates the position of the gate plate (3) via the position of the shift fork (20).

5. A pneumatic cryogenic gate valve according to claim 4, characterized in that: The valve stem (4) is threadedly connected to the piston (16); the threaded connection between the valve stem (4) and the piston (16) is also filled with thread glue; the valve stem (4) is provided with a first conical surface (21); the piston (16) is provided with a second conical surface (22) matched with the first conical surface (21); the valve stem (4) is made of stainless steel metal; the piston (16) is made of aluminum alloy; the first conical surface (21) of the valve stem (4) is sealed with the second conical surface (22) of the piston (16); an O-ring (23) is also provided between the valve stem (4) and the piston (16).

6. A pneumatic cryogenic gate valve according to claim 4, characterized in that: A scraper-type sealing ring is provided between the valve stem (4) and the cylinder (15), the scraper-type sealing ring comprising a non-metallic elastic ring (24) and two metal elastic elements (25) arranged on the same side of the non-metallic elastic ring (24), a gap being provided between the two metal elastic elements (25), and the two metal elastic elements (25) respectively abut against the cylinder (15) and the valve stem (4), a scraper-shaped groove (26) is provided on one side of the non-metallic elastic ring (24) in contact with the valve stem (4), and a scraper-type sealing ring is also provided between the indicator rod (17) and the cylinder (15).

7. The pneumatic cryogenic gate valve according to claim 1, characterized in that: The valve body also includes a packing gland (27) and a packing assembly, wherein the packing gland (27) is connected to the valve cover (2) via bolts, and the packing assembly is crimped between the valve cover (2) and the valve stem (4) via the packing gland (27). The packing assembly includes a lip seal ring (28), a metal retaining ring (29), a lower packing assembly (30), a spacer ring (31), an upper packing assembly (32), and a packing sleeve (33) which are arranged in sequence from bottom to top. One side of the lip seal ring (28) is tightly against the valve stem (4) and the other side is tightly against the valve cover (2).

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