Movable stuffing box and its application in valves

Abstract

The present invention discloses a movable stuffing box and its application in a valve. The movable stuffing box is arranged on the end side of the valve body where the valve plate enters and exits, and includes a box body, a sealing stuffing, a flange gland and fasteners. The two ends of the box body are provided with flanges; wherein, the flange a at one end far from the valve body is connected to the flange gland by fasteners; a pipe sleeve is also arranged between the flange b at one end near the valve body and the valve body; the internal size of the pipe sleeve is larger than the size of the end side where the valve plate enters and exits the valve body, one end of the pipe sleeve is fixed to the end side where the valve plate enters and exits the valve body, and the other end of the pipe sleeve is provided with a flange c; a sealing ring is sandwiched between the flange b and the flange c, and they are connected by fasteners; the connecting hole on the flange c is a long strip hole S, and its long side is along the axial direction of the valve body. The movable stuffing box can be widely used in plug-in valves and glasses valves, and has a simple structure and is easy to manufacture. In particular, it can effectively ensure that the valve plate and the valve seat are pressed everywhere and avoid the interference phenomenon of the traditional fixed stuffing box when the valve plate is pressed.

Description

Technical Field

[0001] The invention relates to a movable stuffing box and application thereof in a valve, in particular to a plug-in valve and a glasses valve with the movable stuffing box. Background Art

[0002] Valves are control components in fluid delivery systems, with functions such as shutoff, regulation, flow diversion, backflow prevention, pressure stabilization, flow diversion, or overflow and pressure relief. They come in a wide variety of varieties and specifications.

[0003] A valve's sealing performance refers to the ability of each sealing part of the valve to prevent leakage of the medium. It is the most important technical performance indicator of a valve. A valve seals at three locations: the contact between the opening and closing parts and the sealing surfaces of the valve seat; the mating between the packing, the valve stem, and the stuffing box; and the connection between the valve body and the bonnet. Leakage at the first location is called internal leakage, commonly known as a loose seal, which will affect the valve's ability to cut off the medium. For cut-off valves, internal leakage is unacceptable. Leakage at the second and third locations is called external leakage, meaning the medium leaks from the valve interior to the exterior. External leakage can cause material loss, environmental pollution, and, in severe cases, accidents. External leakage is particularly unacceptable for flammable, explosive, toxic, or radioactive media, making valves essential for reliable sealing performance. While efforts to achieve excellent sealing performance are relentless, the results are rarely satisfactory.

[0004] Valves used in many applications, such as the inlet and outlet of flue gas turbines in refineries, as well as in desulfurization and sulfur recovery systems, are required by national environmental protection standards to meet zero leakage or US standard Class VI seals. Meeting this standard is particularly challenging for larger valves, and even more challenging in high-temperature applications. For example, the inlet valve of a high-temperature flue gas turbine, designed for flue gas temperatures exceeding 700°C, has a diameter of up to 1850 mm and requires zero leakage. This butterfly valve, manufactured by Adams in Germany, costs over US$500,000 to 600,000 USD per unit. Larger, higher-temperature versions can cost over 10 million RMB. For example, a DN2400 butterfly valve imported from Germany with a design temperature of 680°C costs 12 million RMB. Domestically manufactured butterfly valves of this type also cost between 1 and 3 million RMB per unit. Even with these standards, after a period of use, they often experience leaks due to wear and tear from the media, leading to poor sealing.

[0005] Some domestic refineries have catalytic systems with flue gas temperatures exceeding 680 degrees. In order to achieve zero leakage, water seal tanks are used for sealing. However, this sealing method has the following disadvantages:

[0006] 1. Large pressure loss and increased energy consumption: The flue gas returns from the bottom of the inner tube to the outlet above the outer tube, making two bends, resulting in large pressure loss;

[0007] 2. Large investment: about 1 to 3 million yuan;

[0008] 3. Large area occupied: It occupies additional land and wastes land resources;

[0009] 4. Pollution to the environment: The water used for water seal is polluted by flue gas to form acidic water. If it is discharged directly, it will pollute the environment. If it is discharged after treatment, the treatment cost will be high.

[0010] 5. High cost of use and maintenance: Flue gas is hot, and anti-freezing measures are required. Water needs to be circulated, and a complete control system is required. Anti-freezing and heat preservation measures are required in some cold regions, and water needs to be replenished during operation. The maintenance of these equipment costs about 8-10% of the investment amount each year, and the equipment operating costs are hundreds of thousands of yuan each year;

[0011] 6. Reliability is worse than valves: The water seal system uses a large variety of equipment and instruments, which increases the failure points, so the reliability is poor; in addition, the high-temperature sulfur-containing flue gas reacts with water to corrode the inner tube, which can easily cause the inner tube to fall off. Several cases of inner tube falling off have occurred in China.

[0012] Gas sites also use many water-sealed tanks and require anti-freeze measures, which undoubtedly increases the corresponding costs and problems.

[0013] To achieve zero emissions, some companies use double-layer butterfly valves or two gate valves to add a blower for positive pressure ventilation to achieve zero leakage. This has a complex structure and high cost. The valves used in this situation are often large in size. Due to the large deformation caused by temperature and medium pressure during manufacturing, transportation, installation, and use, it is very difficult to achieve zero leakage. Because of the large deformation caused by various reasons, a blower is used to form an air curtain between the double-layer butterfly valve or two gate valves to achieve sealing. The air volume required for the positive pressure ventilation is very large and it consumes electricity for a long time, so it consumes a lot of energy. In addition, according to the requirements of national or departmental standards, when using sealing air to achieve sealing, the sealing air must be heated to above 100℃. The hot sealing air is blown away at any time, which consumes a lot of energy. This not only further increases energy consumption, but also the hot sealing air is equivalent to steam, which will form a large amount of water in the pipeline. After reacting with harmful media, it will corrode equipment and pipelines. After mixing with dust, it will form agglomerates, scaling, and crystals, which will seriously affect the sealing and opening of the valve. There are countless such examples. The applicant has entered several desulfurization flues and witnessed the above situation firsthand. The applicant has also studied various valves and used them in a variety of different situations, and has a lot of experience with the various drawbacks.

[0014] For example, the Chinese patent "Smoke damper door and its sealing device, authorization publication number CN201526980U" uses an inflatable sealing tube to achieve sealing. However, its disadvantage is that the seal is made of rubber material, which is not resistant to high temperatures and is prone to aging. Another example is the sealing structure of the Chinese patent "Gate valve, application publication number CN104006176A" with the same problem.

[0015] Another example is the Chinese patent "An explosion-proof electric open-type gate valve, authorization announcement number CN204592362U," which has the advantage of good sealing performance. However, its shortcomings are also quite prominent, including:

[0016] 1. Large pressure loss and increased energy consumption: In order to prevent the sealing surface from being eroded, the valve diameter is reduced to protect the sealing surface, which will increase the pressure loss of the valve and thus increase energy consumption;

[0017] 2. Complex structure, high manufacturing cost, and affects the reliability of use: Compared with the conventional plug-in valve, it has an additional valve seat (piston valve seat) and a valve seat sleeve. According to common sense, when the piston actuator is required, even large-sized valves may require multiple sets. Such a complex structure increases the manufacturing cost: If used in high-temperature applications, high-alloy steel must be used, which increases the cost of raw materials; and relative movement can occur between the valve seat and the valve seat sleeve; when the size of the valve seat and the valve seat sleeve is large or impurities enter between the valve seat and the valve seat sleeve, the two are easily stuck; and there is a valve cover 4 for accommodating the entry and exit of the plug-in 2. This valve The cover 4 is equivalent to a box, that is, it has an additional box compared to the conventional gate valve. This box not only increases the manufacturing cost, but also has a dead zone inside, which is easy to accumulate dust. If it is used for a medium such as sulfur-containing flue gas, condensation is easy to form on the hot and cold walls inside. The water formed by condensation will react with the flue gas to form a corrosive medium that corrodes the equipment. At the same time, the formed water will agglomerate, scale, and crystallize with the dust in the flue gas, seriously affecting the opening and closing and sealing of the valve. At this time, the valve seat and the valve seat sleeve are very likely to get stuck due to agglomeration. For example, a groove is formed on the valve seat below the valve body. When dust accumulates in this groove, it affects the closing of the valve. After the condensed water enters this groove, it is easy to agglomerate, scale, crystallize, or even freeze with the dust in the medium. The above factors not only make its structure complex, difficult to manufacture, and increase the cost, but also naturally affect its reliability in use.

[0018] Another example is the Chinese patent "A two-way sealed knife gate valve, authorization announcement number CN203453505U", which has the advantages of novel conception, but its shortcomings are as follows:

[0019] 1. Various factors in the actual application process make it impossible to achieve truly effective sealing: First, when the gate valve is connected to the on-site pipeline, if the movable elastic sealing sleeve is inside the pipeline, the pressing force of the sealing ring cannot be adjusted. If the outer axial end face of the elastic sealing sleeve 3 is connected to the on-site pipeline, due to the large deformation often caused during on-site installation, this is especially true for large-sized valves (there is almost no on-site installation without deformation, and there are also deformations caused by the various factors mentioned above), it is easy to displace the upper part of the movable elastic sleeve 3 axially outward, because this upper part is the weakest, resulting in: the upper part of the sealing ring is very likely not to contact the valve plate, and the upper part of the sealing ring on the other side may also be the same. At this time, it is difficult to rely on screws to compress the sealing ring through the elastic sealing sleeve, especially after the valve body is torsional deformed, and its sealing effect is even more out of the question; secondly, in high-temperature environments, rubber cannot be used as sealing filler, and graphite packing is usually used, as described in the instruction manual Figure 2 The sealing filler and the sealing ring 10 below the middle screw 9 are both made of graphite packing. When the sealing ring 10 is worn, if it is re-tightened by the elastic sealing sleeve, the sealing filler below the screw 9 is not worn, and interference problems will arise during re-tightening. In fact, it is difficult to tighten, and the seal cannot be achieved. Furthermore, the diameter of the valve stem 6 is usually several tens of millimeters, and the diameter of the stem nut 11 is larger than the diameter of the valve stem 6. In addition, the valve cover plate connected to the movable elastic sealing sleeve is thick, and the axial length of the movable elastic sealing sleeve is long, so its axial rigidity is large and the elasticity is poor, which makes it difficult to ensure that the sealing ring 10 and the sealing ring 8 on the other side are tightened everywhere. Similarly, practice has also proved that when the valve body is torsionally deformed, it is almost impossible to tighten it completely, and there is no way to talk about sealing.

[0020] 2. There are many machined parts, the structure is complex, the cost is high and the reliability of use is difficult to guarantee: Similar to the previous patent, the dust accumulation in the groove under the valve body affects the closing of the valve, and the condensed water entering the groove is easy to agglomerate, scale, crystallize, and even freeze with the dust in the medium, which seriously affects the reliability of use.

[0021] In fact, many gate valves at home and abroad have similar structures to the above one, and the above technical problems are common.

[0022] A single plate eye valve (open type) manufactured by Germany's ZMMERMANN & JANSEN Company, the United States' SchuF Company and Tianjin Tanggu Jinbin Valve Co., Ltd. Figure 1 As shown, in order to tighten, an expansion joint is required. The double-plate eye valve (closed type) they manufacture has two similar boxes symmetrically fixed on both sides of the axis outside the valve body, such as Figure 2As shown, it has the same problems as the aforementioned Chinese patent "An explosion-proof electric open-type plug-in valve, authorization announcement number CN204592362U", such as complex structure, increased production cost and dust accumulation and condensation in the box; at the same time, the eye valve of this structure has sealed cavities on both sides. When the size is large, a head must be used. There are N actuators outside the valve body to press the valve plate, and the whole is particularly bulky. Naturally, its manufacturing cost, transportation cost, installation and maintenance cost are correspondingly increased, and its reliability in use is inevitably reduced.

[0023] The American company SchuF also manufactures an eye valve that combines open and closed types. Figure 2 On the basis of the valve, a guide rail is fixed above the valve, and the sealing chambers on both sides are hung on the guide rails. The sealing chambers on both sides can be separated. The advantages of this structure are: after the sealing chamber is opened, there will be no internal leakage, and external leakage can also be checked. Its disadvantages are: in addition to the problems of the above-mentioned eye valve, after the sealing chamber is opened, the space occupied is particularly large, which is equivalent to the width of 4-5 valve bodies, and the sealing surfaces and guide rails between the two valve bodies and the sealing chamber are added. When the valve is closed, in order to prevent internal leakage, the sealing chamber must be opened. If the medium in the chamber is toxic or flammable, there is a safety hazard, and more troublesome measures need to be taken. After the sealing chamber is opened, debris may enter the chamber or the sealing surface and the sealing surface with the valve body may freeze, affecting the reliability of use and possibly damaging the soft seal between the two.

[0024] In addition, other types of valves, such as the Chinese patented "Flue Baffle Hinged Four-Bar Sealing Mechanism, Authorization Announcement No. CN201100649U" and "Four-Bar Sealing Door, Authorization Announcement No. CN202165597U," take up less space, have a simpler structure, and offer better sealing than existing flapper valves. However, they also have the following drawbacks:

[0025] 1. Manufacturing precision and deformation caused by manufacturing, transportation, installation, and use make it difficult to achieve zero leakage. When the size is large, the unavoidable deformation makes it even more difficult to achieve zero leakage. Strict positional accuracy requirements are placed on the four-link rod. Moreover, the lengths of the four-link rods are different, and the different thermal deformations can easily cause displacement between the valve plate and the valve seat, thereby easily creating a gap and affecting the sealing effect.

[0026] 2. The four-bar linkage inside the flue has several friction pairs. When the medium in the flue contains dust, it is easy to get stuck. Especially after condensation, the dust forms agglomerates and scales, which makes it more likely that the friction pairs will get stuck or locked. Because it is located inside the flue and cannot be lubricated, it is impossible to repair it without disassembling it. If it is repaired, it must be lowered from a high altitude, which is expensive and time-consuming. This can easily cause production stoppages and losses.

[0027] 3. When used in high-temperature applications, the four-bar linkage must be made of expensive high-alloy steel, making it expensive. In some high-temperature applications, the valve body requires a thermal insulation and wear-resistant lining. For example, if the medium temperature is 680°C, which is also the temperature of the valve trim, with the thermal insulation lining, the valve body temperature is less than 200°C. The expansion difference between the annular valve seat and the valve body exceeds 1%, causing the valve plate and valve body to collide, which can cause yielding or high-temperature creep, thus affecting the seal.

[0028] The valve is not sealed tightly, resulting in non-compliance with environmental protection standards; and hot flue gas will flow back, which will corrode the fan and prevent workers from entering the flue to carry out construction.

[0029] As can be seen, valve sealing has always been a technical challenge in this field, especially for large-sized valves. These include factors such as manufacturing accuracy, deformation caused by transportation and installation, deformation caused by the temperature and pressure of the medium during use, dust or impurities on the valve seat that affect the seal, and erosion and wear of the sealing surface by particles in the medium. When valves with thermal linings and annular seats are used in high-temperature environments, valve seat deformation and high-temperature creep between the seat and the valve body undoubtedly affect the effective sealing of the valve. Summary of the Invention

[0030] In view of the above-mentioned problems existing in the prior art, the present invention aims to disclose a movable stuffing box and discloses its application to, for example, a gate valve and an eye valve, so as to solve the sealing problem caused by interference when the gate valve adopts a clamping mechanism to close and solve the problem of complex structure and high cost caused by the double-plate eye valve in order to achieve sealing.

[0031] The technical solution of the present invention is achieved as follows:

[0032] A movable stuffing box is arranged on the end side of the valve body where the valve plate enters and exits, and includes a box body with a flange, sealing stuffing, a flange gland and fasteners;

[0033] The box body has flanges at both ends; wherein, the flange a at the end far from the valve body is connected to the flange gland by fasteners; and a pipe sleeve is also provided between the flange b at the end near the valve body and the valve body;

[0034] The inner dimensions of the sleeve are larger than the dimensions of the end of the valve plate where the valve plate enters and exits the valve body; one end of the sleeve is fixed to the end of the valve plate where the valve plate enters and exits the valve body, and the other end is provided with a flange c; a sealing ring is sandwiched between the flanges b and c, and the two are connected by fasteners; specifically, the sleeve is a square tube structure;

[0035] The connecting hole on the flange c is an elongated hole S, the long side of which is along the axial direction of the valve body, and the size of the elongated hole S is larger than the outer diameter of the fastener matched therewith.

[0036] More preferably, in order to improve the mobility of the movable stuffing box, the stuffing box further includes a movable flange and a friction-reducing structure;

[0037] The movable flange is sleeved on the outer periphery of the pipe sleeve, parallel to the flange c, and located between the flange c and the valve body; specifically, corresponding to the sleeve of the square tube structure, the movable flange is a rectangular ring structure;

[0038] The friction reducing structure is sandwiched between the movable flange and flange c;

[0039] The flange b, flange c, friction reducing structure and movable flange are connected in sequence through fasteners.

[0040] Specifically, the sealing filler and sealing ring are made of rubber, graphite packing, oil-impregnated packing or polytetrafluoroethylene;

[0041] The friction reduction structure adopts graphite packing, oil-immersed packing, polytetrafluoroethylene plate or N uniformly distributed plane universal balls.

[0042] The invention also discloses a valve with the movable stuffing box.

[0043] Specifically, the valve may be a gate valve.

[0044] Alternatively, the valve can be a double-plate glasses valve; the stuffing box is arranged at the end side of the valve body corresponding to the direction in which the valve plate enters the valve body; and it also includes a sealing cavity, which is opposite to the stuffing box and is fixed at the end side of the valve body corresponding to the direction in which the valve plate leaves the valve body to accommodate the opened valve plate.

[0045] Furthermore, for the double-plate glasses valve, in order to avoid long-term contact between the medium and the inner wall of the sealing cavity, the stuffing box includes a first stuffing box and a second stuffing box, which are symmetrically arranged on the two end sides of the valve plate entering and exiting the valve body. The first stuffing box is located on the valve body end side corresponding to the direction in which the valve plate enters the valve body, and the second stuffing box is located on the valve body end side corresponding to the direction in which the valve plate leaves the valve body; its sealing cavity is fixed on the flange cover of the second stuffing box.

[0046] Furthermore, the valve includes a compensator fixed to the valve body, located on the side of the valve plate near the valve seat, with its axis parallel to the axis of the valve body. When the valve plate's clamping mechanism is released, the compensator's piston rod abuts against flange b of the stuffing box, pushing the valve plate away from the valve seat. Specifically, the compensator is a pneumatic actuator.

[0047] Furthermore, in order to ensure the sealing effect, a groove is provided on the axial surface of the valve seat of the valve body, in which a sealing filler is accommodated; specifically, the sealing filler protrudes from the groove and the axial sealing surface of the valve seat to ensure the sealing effect.

[0048] More preferably, the groove is in a narrow mouth and wide belly shape, such as a dovetail groove.

[0049] Furthermore, when the valve is in an open state, there is a distance between the valve plate and the inner wall of the sleeve that is greater than the axial displacement of the valve plate.

[0050] Specifically, the clamping mechanism of the valve plate is fixed on the valve body, and includes multiple sets of linear cylinders or oil cylinders with piston rods, which are evenly arranged around the valve seat. The piston rods of the clamping mechanism extend into the valve body perpendicular to the valve plate.

[0051] An electric heater is provided in the valve plate to solve the problems of corrosion, scaling, agglomeration and crystallization caused by condensation on the hot and cold walls of existing plug-in valves and eye valves, which affect the sealing and closing of the valves.

[0052] The working principle of the present invention is:

[0053] 1. When the valve described in the present invention is used on a horizontal pipeline, its valve plate is perpendicular to the ground. After the actuator a moves the valve plate to the valve closing position (usually located at the bottom), the actuator b drives the shaft to rotate, and the cam fixed on the shaft pushes the valve plate to displace toward the valve seat, and finally presses the valve plate against the valve seat; during this displacement process, the valve plate will drive the stuffing box described in the present invention to displace synchronously; after the actuator b is released, the compensator pushes the stuffing box back to its starting position before closing and drives the valve plate away from the valve seat.

[0054] 2. When the valve described herein is used in a vertical pipeline, its valve disc is parallel to the ground and positioned below the valve seat. After actuator a moves the valve disc to the closed position, actuator b rotates the shaft, causing a cam attached to the shaft to displace the valve disc toward the valve seat, ultimately pressing it against the valve seat. During this displacement, the valve disc simultaneously displaces the stuffing box described herein. When actuator b is released, the weight of the valve disc pushes the stuffing box back to its initial position before closing, driving the valve disc away from the valve seat. Because the weight of the valve disc can move the stuffing box back to its initial position, a compensator is not required in this application.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] The movable stuffing box disclosed in this invention effectively ensures that the valve plate and valve seat are consistently pressed together, avoiding the interference of traditional fixed stuffing boxes when the valve plate is pressed together. This ensures that the valve plate and valve seat are in close contact, ensuring both sealing performance and effectiveness. The combination of soft and hard sealing methods solves the existing problem of large-sized gate valves or eye valves being difficult to achieve zero leakage after deformation. At the same time, it reduces the requirements for valve manufacturing precision and reduces manufacturing costs.

[0057] At the same time, the valves disclosed in the present invention mainly include gate valves and double-plate glasses valves. Compared with various existing valve products, they have the characteristics of simple structure, easy production, convenient use, and significant cost savings while ensuring sealing performance, which undoubtedly better meets customer requirements and expectations:

[0058] For example, compared to existing double-slot valves, the valve disclosed in this invention eliminates one valve and its various actuators, significantly reducing costs. This is especially true for high-temperature applications, where high-alloy steel, such as 06Cr25Ni20 steel, is very expensive, costing 40,000 to 80,000 yuan per ton. This significantly reduces manufacturing costs and reduces the burden on users. Furthermore, double-slot valves require sealing air between the two slots, increasing operating costs. Some applications require hot sealing air, further increasing operating costs. This hot sealing air often condenses within the pipes, forming large amounts of water. For example, when the medium is sulfur-containing flue gas, the water reacts with the sulfur to form a highly corrosive medium, corroding the flue or insulation lining.

[0059] For example, compared with the four-bar linkage actuator, we know that the four-bar linkage actuator has many moving parts, cannot be lubricated, the rotating friction pair is easy to get stuck, cannot be repaired without disassembly, poor reliability or loose sealing, and is difficult to open when the pressure is high or the size is large. Obviously, the use of the present invention solves the above problems.

[0060] The double-plate glasses valve disclosed in the present invention prevents sulfur-containing flue gases from remaining in the sealed cavity for extended periods of time. Consequently, the valve is less susceptible to condensation, scaling, caking, and crystallization, ensuring flexible and reliable opening and closing, as well as sealing performance and improved operational reliability. This also prevents condensed water from reacting with the medium and corroding the valve, pipes, or insulation lining.

[0061] At the same time, the structure of the present invention can ensure that even if the valve is greatly deformed after installation, problems such as switch jamming or loose sealing will not occur.

[0062] Furthermore, the valve disclosed in the present invention does not require the bellows of the blind plate valve, thus avoiding the problem of the easily damaged bellows affecting the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1is a schematic structural diagram of a movable stuffing box according to embodiment 1 of the present invention;

[0064] Figure 2 2 is a schematic structural diagram of a gate valve according to embodiment 2 of the present invention when used vertically;

[0065] Figure 3 yes Figure 2 AA cross-sectional view;

[0066] Figure 4 2 is a schematic structural diagram of a gate valve according to embodiment 2 of the present invention when used horizontally;

[0067] Figure 5 2 is a schematic structural diagram of a double-plate eye valve 1 according to Example 3 of the present invention;

[0068] Figure 6 1 is a schematic structural diagram of a double-plate eye valve II according to Example 4 of the present invention.

[0069] In the figure: 1. Valve body 2. Valve plate 3. Valve seat 4, 4'. Stuffing box 401, 401'. Flange cover 402. Flange a 403. Box 404. Sealing packing 405. Flange b 406. Flange c 407. Sealing ring 408. Sleeve 409. Movable flange 410. Friction reduction structure 411, 412. Fastener 5. Compensator 6. Sealing chamber 7. Electric heater 8. Actuator a 801. Actuator bracket 9. Clamping mechanism 901. Actuator b 902. Shaft 903. Shaft sealing mechanism 904. Cam 10. Sealing packing. DETAILED DESCRIPTION

[0070] The present invention will now be described in further detail with reference to the accompanying drawings.

[0071] Example 1: Movable stuffing box

[0072] According to a movable stuffing box 4 of the present invention, Figure 1 As shown, it is arranged on the end side of the valve body 1 where the valve plate 2 enters and exits, and includes a box body 403 with a flange, a sealing packing 404, a flange gland 401 and fasteners;

[0073] The box body 403 has flanges at both ends; wherein, the flange a402 at the end far from the valve body is connected to the flange gland 401 via a fastener 412; and a pipe sleeve 408 is further provided between the flange b405 at the end near the valve body and the valve body 1;

[0074] The internal dimensions of the pipe sleeve 408 are larger than the dimensions of the end side of the valve plate 2 entering and exiting the valve body; one end of the pipe sleeve 408 is fixed to the end side of the valve plate entering and exiting the valve body 1, and the other end has a flange c406; a sealing ring 407 is sandwiched between the flange b405 and the flange c406, and is connected by a fastener 411; specifically, the sleeve 408 adopts a square tube structure; when the valve is open, there is a distance between the valve plate 2 and the inner wall of the sleeve 408 that is greater than the axial displacement of the valve plate.

[0075] The fasteners 411 and 412 may both be screw and nut structures.

[0076] In order to ensure that the stuffing box is movable and moves smoothly, the connecting hole on the flange c406 is a long hole S, the long side of the long hole S is along the axial direction of the valve body 1, and the size of the long hole S is larger than the outer diameter of the fastener 411 that matches it.

[0077] In this way, a movable stuffing box 4 is formed.

[0078] In order to improve the mobility of the movable stuffing box 4, the stuffing box 4 may be further provided with a movable flange 409 and a friction reducing structure 410;

[0079] The movable flange 409 is sleeved on the outer periphery of the pipe sleeve 408, parallel to the flange c406 and located between the flange c406 and the valve body 1; specifically, corresponding to the square pipe structure of the sleeve 408, the movable flange 409 can generally adopt a rectangular ring structure;

[0080] The friction reducing structure 410 is sandwiched between the movable flange 409 and the flange c406 to improve the flexibility of the movement of the stuffing box 4;

[0081] The flange b405, flange c406, friction reducing structure 410 and movable flange 409 are connected in sequence by fasteners 411.

[0082] The movable stuffing box 4 can be widely used in various valves including gate valves and glasses valves, for example:

[0083] Example 2: Gate Valve

[0084] A gate valve, such as Figures 2 to 4 As shown, it includes a valve body 1, a valve plate 2, a valve seat 3, a movable stuffing box 4, an actuator a8, a valve plate clamping mechanism 9, and a compensator 5; the valve body 1 is fixed together with the actuator bracket 801 and the clamping mechanism 9, the valve seat is connected to the valve body 1, and the actuator a is connected to the valve plate 2;

[0085] The clamping mechanism of the valve plate is fixed on the valve body, including an actuator b901, a shaft 902, a shaft sealing mechanism 903 and a cam 904 fixed on the shaft 902. The actuator includes multiple sets of linear cylinders or oil cylinders with piston rods, which are evenly arranged around the valve seat, and the piston rods extend into the valve body perpendicular to the valve plate.

[0086] The stuffing box 4 is provided on the valve body 1 at the end side where the valve plate 2 enters and exits. Its structure and installation are as described in Example 1 and will not be described again here.

[0087] When the valve is used on a horizontal pipeline, the valve plate 2 is perpendicular to the ground. Figure 2 , Figure 3 As shown, after the actuator a8 sends the valve plate 2 into the valve closing position (usually located at the lower part) in the valve body 1, the actuator b901 drives the shaft 902 to rotate, and the cam 904 fixed on the shaft 902 pushes the valve plate 2 to move toward the valve seat 3, and finally presses the valve plate 2 onto the valve seat 3; during this displacement process, the valve plate 2 will drive the stuffing box 4 to move synchronously; after the actuator b901 is released, the compensator 5 pushes the stuffing box 4 back to the starting position before closing and drives the valve plate 2 to leave the valve seat 3.

[0088] When the valve is used on a vertical pipeline, its valve plate is parallel to the ground, such as Figure 4 As shown, the valve plate 2 is positioned below the valve seat 3. After actuator a8 moves the valve plate 2 into the valve body 1 to the closed position, actuator b901 rotates shaft 902. A cam 904 attached to shaft 902 pushes the valve plate 2 toward the valve seat 3, ultimately pressing the valve plate 2 against the valve seat 3. During this displacement, the valve plate 2 also causes the stuffing box 4 to move synchronously. After actuator b901 is released, the weight of the valve plate 2 pushes the stuffing box 4 back to its initial position before closing and moves the valve plate 2 away from the valve seat 3. Because the weight of the valve plate 2 can move the stuffing box 4 back to its initial position, compensator 5 is not required in this application.

[0089] Typically, the compensator 5 is a hydraulic compensator with an accumulator, and a pneumatic actuator may be used.

[0090] The actuator a8 can be a linear cylinder or an oil cylinder.

[0091] The actuator b901 can be a pneumatic actuator or an electric actuator.

[0092] The cam 904 may have an Archimedean spiral or an involute profile.

[0093] In order to ensure the sealing effect, the axial surface of the valve seat 3 is usually provided with a groove, such as a dovetail groove, in which a sealing filler 10 is accommodated. When in use, the sealing filler 10 protrudes from the groove and the axial sealing surface of the valve seat to ensure the sealing effect.

[0094] The sealing ring 407 and the sealing filler 404, 10 are made of rubber, graphite packing, oil-impregnated packing or polytetrafluoroethylene.

[0095] The friction reducing structure 410 is made of one of graphite packing, oil-impregnated packing, polytetrafluoroethylene plate or N uniformly distributed planar universal balls.

[0096] In order to further solve the problem of corrosion, scaling, agglomeration and crystallization caused by condensation on the hot and cold walls of the existing plug valve and eye valve, which affects the sealing and closing of the valve, an electric heater 7 is provided in the valve plate 2 of the valve.

[0097] Example 3: Double-plate glasses valve I

[0098] A double plate eye valve I, such as Figure 5 As shown, it includes: a valve body 1, a valve plate 2, a valve seat 3, a movable stuffing box 4, a compensator 5, a sealing chamber 6, an actuator a8 and an actuator bracket 801 and a valve plate clamping mechanism 9.

[0099] The stuffing box 4 is arranged on the end side of the valve body 1 corresponding to the direction in which the valve plate 2 enters the valve body;

[0100] The sealing cavity 6 is opposite to the stuffing box 4 and is fixed to the end side of the valve body 1 corresponding to the direction in which the valve plate 2 leaves the valve body to accommodate the opened valve plate 2.

[0101] The structure, working mode and principle of the stuffing box 4 are as described in Example 1 and Example 2, and will not be repeated here.

[0102] Example 4: Double-plate glasses valve II

[0103] A double plate glasses valve II, such as Figure 6 As shown, the difference from Example 3 is that the glasses valve II is provided with two movable stuffing boxes, namely a first stuffing box 4 and a second stuffing box 4', which are symmetrically arranged at the two end sides of the valve plate entering and exiting the valve body 1. The first stuffing box 4 is located at the end side of the valve body 1 corresponding to the direction in which the valve plate 2 enters the valve body, that is, the stuffing box described in Example 3, and the second stuffing box 4' is located at the end side of the valve body 1 corresponding to the direction in which the valve plate 2 leaves the valve body;

[0104] Correspondingly, the sealing cavity 6 is fixed on the flange gland 401 ′ of the second stuffing box 4 ′.

[0105] The second stuffing box 4' is also a movable stuffing box, and its structure, working mode and principle are consistent with those of the first stuffing box 4, as described in Examples 1 and 2; the synchronous displacement of the second stuffing box 4' along with the displacement of the valve plate 2 relative to the valve seat 3 effectively avoids long-term contact between the medium and the inner wall of the sealing cavity 6.

[0106] The above description is only a preferred specific embodiment of the present invention. The present invention can be used in many occasions or for a variety of valves, but the scope of protection of the present invention is not limited thereto, and is even less likely to be limited to the gate valve and the four-bar mechanism sealing door. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solution and inventive concept of the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A movable stuffing box, arranged on the end side of the valve body where the valve plate enters and exits, comprises a box body with a flange, a sealing stuffing, a flange gland and fasteners, characterized in that: The two ends of the box body are provided with flanges; wherein the flange a at the end far from the valve body is connected to the flange gland via fasteners; and a pipe sleeve is also provided between the flange b at the end near the valve body and the valve body; The inner dimension of the pipe sleeve is larger than the dimension of the end side of the valve plate entering and exiting the valve body; one end of the pipe sleeve is fixed to the end side of the valve plate entering and exiting the valve body, and the other end is provided with a flange c; a sealing ring is sandwiched between the flange b and the flange c, and they are connected by fasteners; The connecting hole on the flange c is an elongated hole S, the long side of which is along the axial direction of the valve body, and the size of the elongated hole S is larger than the outer diameter of the fastener matched therewith.

2. The stuffing box according to claim 1, characterized in that: It also includes a movable flange and a friction-reducing structure; The movable flange is sleeved on the outer periphery of the pipe sleeve, parallel to the flange c and located between the flange c and the valve body; The friction reducing structure is sandwiched between the movable flange and flange c; The flange b, flange c, friction reducing structure and movable flange are connected in sequence through fasteners.

3. The stuffing box according to claim 2, characterized in that: The sealing filler and sealing ring are made of rubber, graphite packing, oil-impregnated packing or polytetrafluoroethylene; The friction reduction structure adopts graphite packing, oil-immersed packing, polytetrafluoroethylene plate or N uniformly distributed plane universal balls.

4. A valve having a movable stuffing box as claimed in claim 1 or 2.

5. The valve according to claim 4, which is a gate valve.

6. The valve according to claim 4 is a double-plate glasses valve, characterized in that: The stuffing box is arranged on the end side of the valve body corresponding to the direction in which the valve plate enters the valve body; It also includes a sealing cavity, which is opposite to the stuffing box and fixed to the end side of the valve body corresponding to the direction in which the valve plate leaves the valve body to accommodate the opened valve plate.

7. The valve according to claim 4 is a double-plate glasses valve, characterized in that: The stuffing box comprises a first stuffing box and a second stuffing box, which are symmetrically arranged at two ends of the valve body where the valve plate enters and exits, the first stuffing box is located at the end of the valve body corresponding to the direction in which the valve plate enters the valve body, and the second stuffing box is located at the end of the valve body corresponding to the direction in which the valve plate leaves the valve body; It also includes a sealing cavity which is fixed on the flange gland of the second stuffing box.

8. The valve according to any one of claims 5 to 7, characterized in that: It also includes a compensator; it is fixed on the valve body, located on the side of the valve plate close to the valve seat, and its axis is parallel to the axis of the valve body; when the clamping mechanism of the valve plate is released, the piston rod of the actuator of the compensator rests on the flange b of the stuffing box.

9. The valve according to any one of claims 5 to 7, characterized in that: The axial surface of the valve seat of the valve body is provided with a groove in which a sealing filler is accommodated.

10. The valve according to claim 9, characterized in that: The groove is in a shape of a narrow mouth and a wide belly.

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