A flexible connection planar rotary joint for high temperature trough collectors

Abstract

This invention belongs to the field of flexible connection components for parabolic trough collectors and the technology of solar thermal power generation. It discloses a flexible connection planar rotary joint for high-temperature parabolic trough collectors, comprising: a shell, a first bushing, four first metal-edged wire-reinforced sealing rings, two second metal-edged wire-reinforced sealing rings, a sealing ring support, a hollow shaft, a sealing ring pressure ring, a second bushing, two anti-rotation pins, adjusting bolts, a threaded flange, injectable soft sealing filler, and three injection port sealing bolts. The shell serves as the base of the planar rotary joint, with three evenly distributed threaded injection ports on its circumference for connecting a one-way valve and a high-pressure injection gun to add injectable soft filler. After the sealing material is injected, the injection threads on the shell are plugged using the sealing bolts on the injection ports. The bushing is located at the bottom of the inner cavity of the shell, and a first set of sealing rings and a second set of sealing rings are respectively arranged on both sides of the injectable soft filler sealing cavity. The anti-rotation pins prevent the second bushing from rotating under the dry friction torque generated by the rotation of the hollow shaft.

Description

Technical Field

[0001] This invention belongs to the field of flexible connection technology of solar thermal power generation collectors and pipes, and specifically relates to a planar rotary joint for flexible connection of high temperature trough collectors. Background Technology

[0002] Parabolic trough solar thermal power generation systems have become one of the important development directions of new energy sources internationally due to their outstanding advantages such as excellent power generation quality, energy storage, environmental friendliness, and mature technology. To reduce costs, the development of molten salt tanks using molten salt as the medium is imperative. However, due to the high operating temperature (560℃), high pressure (4MPa), and service life of 25 to 30 years required for molten salt tanks, flexible connection technology between molten salt tanks and pipelines has not yet been successfully developed, both domestically and internationally. In foreign molten salt tank test circuits, flexible connections use corrugated metal pipes, but their application has been limited due to cost and reliability issues. While some molten salt tank test benches have adopted hard-seal flat rotary joints, their higher cost and sealing reliability have also hindered their widespread adoption. All of these factors directly affect the development and commercialization of molten salt tank technology.

[0003] For the flexible connection of mature parabolic trough collectors that use heat transfer oil and water as heat transfer media, the ball joints imported from the United States are currently used both domestically and internationally. However, there are only two companies in the world that can provide this product, which greatly restricts the development and application of parabolic trough solar thermal power generation technology in my country. Summary of the Invention

[0004] In view of this, the present invention provides a planar rotary joint for flexible connection of high-temperature trough solar collectors. It is suitable for flexible connection of high-temperature molten salt troughs below 560°C and flexible connection systems of trough solar collectors using heat transfer media such as heat transfer oil or water below 430°C. It not only solves the flexible connection problem of molten salt troughs with working pressure of 4MPa and high temperature of 560°C, but is also suitable for flexible connection of trough solar collectors using heat transfer oil and water as heat transfer media below 430°C. It achieves reliable sealing, strong sealing performance, reliable operation, low rotational torque, and stable operation. It enables complete and true online maintenance under certain pressure and temperature without disassembling or replacing any parts. It not only solves the global problem of planar rotary joints for flexible connection of high-temperature molten salt trough solar collectors, filling a gap at home and abroad, but can also completely replace imported spherical joints for flexible connection of heat transfer media such as heat transfer oil and water below 430°C.

[0005] The purpose of this invention is to provide a flexible connecting planar rotary joint for high-temperature trough solar collectors, comprising: a shell (1), a first bushing (2), four first metal-edged wire-reinforced sealing rings (3), two second metal-edged wire-reinforced sealing rings (4), a sealing ring support (5), a hollow shaft (6), a sealing ring pressure ring (7), a second bushing (8), two anti-rotation pins (9), an adjusting bolt (10), a threaded flange (11), injectable soft filler (12), and three injection port sealing bolts (13), wherein,

[0006] The housing (1) is the base of the planar rotary joint and is used to install and fix other components. The three injection thread ports are evenly distributed on the housing (1) for adding the injectable soft filler (12) through the three injection thread ports during assembly and online maintenance. After adding the injectable soft filler (12) to form a sealing material, the three injection port sealing bolts (13) are used to seal the three injection thread ports on the housing (1) respectively.

[0007] The first bushing (2) is disposed at the bottom of the inner cavity of the housing (1);

[0008] A first set of sealing rings and a second set of sealing rings are respectively provided on both sides of the injectable soft filler (12); the first set of sealing rings is composed of one or more first metal-edged wire reinforced sealing rings (3) and one or more second metal-edged wire reinforced sealing rings (4); the second set of sealing rings is composed of four or more other first metal-edged wire reinforced sealing rings (3) and one or more second metal-edged wire reinforced sealing rings (4), the two sets of sealing rings are located on both sides of the injectable soft filler (12), and a sealing ring support (5) is provided between the two sets of sealing rings. The two sets of sealing rings are connected to the housing (1) The hollow shaft (6) and the sealing ring support (5) form a sealing cavity for injectable soft filler (12). During assembly, pressure is applied to the second bushing (8) using a tool. The second bushing (8) directly applies pressure to the hollow shaft (6), and at the same time, pressure is transmitted to the second set of sealing rings and the first set of sealing rings through the sealing ring pressure ring (7) and the sealing ring support (5), so that the two sets of sealing rings are reliably compressed to ensure sealing performance. The sealing ring support (5) is provided with several round holes or elongated holes evenly arranged radially. The anti-rotation pin (9) is used to prevent the first bushing (2) from rotating under the action of dry friction generated by the high temperature rotation of the hollow shaft (6).

[0009] The adjusting bolt (10) is used for online maintenance of leaks caused by wear and consumption of the sealing material after long-term operation, including: increasing the compression of the first metal-edged reinforcing sealing ring (3) and the second metal-edged reinforcing sealing ring (4) by adjusting the adjusting bolt (10) to eliminate the leak; adding injectable soft filler (12) to the sealing cavity of the injectable soft filler (12) formed between the two sets of sealing rings and the housing (1), the hollow shaft (6) and the sealing ring support (5);

[0010] The threaded flange (11) is used for axial fixation of all components installed in the housing (1), and the adjusting bolt (10) is installed on the second bushing (8); wherein, pressure is applied to the second bushing (8) using an assembly tool and transmitted to the hollow shaft (6), and at the same time transmitted to the four first metal-edged metal wire reinforced sealing rings (3) and two second metal-edged metal wire reinforced sealing rings (4) through the sealing ring pressure ring (7) and the sealing ring support (5), then the threaded flange (11) is rotated to the bottom, and the adjusting bolt (10) is installed on the second bushing (8) so that its end contacts the sealing ring pressure ring (7);

[0011] During assembly, injectable filler (12) is injected into the injectable soft filler sealing cavity according to the required pressure. The injectable soft filler (12) fills the entire sealing cavity and plays a key sealing role. After long-term operation, leakage caused by the wear and consumption of the sealing material can be repaired online by adding the injectable soft filler again.

[0012] The first bushing (2) and the second bushing (8) serve as supporting components for the hollow shaft (6) and form a rotating friction pair with the hollow shaft (6). At the same time, the second bushing (8) also acts as a thrust plate, bearing the outward axial thrust applied by the hollow shaft (6) under the working medium pressure.

[0013] Preferably, the dynamic sealing surface of the hollow shaft (6) is provided with a composite structure of a slope + one or more spherical surfaces + a slope, so that the second metal-edged wire-reinforced sealing ring (4) and the hollow shaft (6) are sealed by a slope, and the injectable soft filler (12) and the hollow shaft (6) are sealed by a slope + spherical surface. These are the key to improving the sealing effect and sealing life. The slope and spherical surfaces of the dynamic sealing surface of the hollow shaft (6) can also be designed as other curved surface structures, such as full slope, elliptical surface, etc., to increase the sealing performance. Correspondingly, the cross-section of the inner hole of the second metal-edged wire-reinforced sealing ring (4) should also be changed accordingly.

[0014] Preferably, the sealing ring support (5) is provided with evenly distributed holes or elongated holes, so that the injectable soft filler (12) fills the entire injectable soft filler sealing cavity.

[0015] Preferably, for the case where high-temperature molten salt is used as the medium, since high-temperature molten salt (560°C) has strong oxidizing and corrosive properties, the first metal-edged wire-reinforced sealing ring (3) and the second metal-edged wire-reinforced sealing ring (4) are vermiculite sealing rings reinforced with metal edging and wire. For the case where heat transfer oil and water are used as the medium, since the medium has no or very mild oxidizing and corrosive properties, and the operating temperature is low (below 430°C), the first metal-edged wire-reinforced sealing ring (3) and the second metal-edged wire-reinforced sealing ring (4) are flexible graphite sealing rings reinforced with metal edging and wire. Metal edging and wire reinforcement are used to improve the rigidity, erosion resistance and long-term sealing performance of the sealing ring. The edging structure of the first metal-edged wire-reinforced sealing ring (3) can be L-shaped or U-shaped. The U-shaped structure has better sealing performance than the L-shaped structure, but the rotational friction torque will increase.

[0016] Preferably, when high-temperature molten salt is used as the medium, the main components of the injectable soft filler (12) are expanded vermiculite particles and mineral fibers; when heat transfer oil and water are used as the medium, the main components of the injectable soft filler (12) are worm-shaped expanded graphite particles and graphite / carbon fiber.

[0017] Preferably, all metal parts other than the sealing material are made of the same metal material to prevent dimensional fit problems caused by different coefficients of thermal expansion at high temperatures; wherein, the metal parts other than the sealing material include the housing (1), the hollow shaft (6), the first bushing (2), the sealing ring support (5), the sealing ring pressure ring (7), the first bushing (2) and the second bushing (8) and the threaded flange (11). The second bushing (8) can be made of the same material, or it can be made of other metal materials with good dry friction performance and similar or slightly larger coefficients of thermal expansion.

[0018] Preferably, when high-temperature molten salt is used as the medium, the metal material is stainless steel or a high-temperature alloy material that is resistant to high-temperature oxidation, high-temperature creep and has good weldability. The second bushing (8) can also be made of high-nickel ductile iron with a slightly larger coefficient of expansion. When heat transfer oil or water is used as the medium, the metal material is selected as austenitic stainless steel or high-quality carbon steel or heat-resistant alloy steel with good weldability that is compatible with the working temperature. Since the working temperature is low when heat transfer oil and water are used as heat transfer media, the material of the second bushing (8) can be selected as ductile iron or copper alloy with a coefficient of expansion close to or slightly larger than the temperature to reduce the friction force and friction torque of high-temperature dry friction.

[0019] Preferably, when high-temperature molten salt is used as the medium, the outer surface of the hollow shaft (6) is laser-clad with Stellite 6 / 6A alloy, and the inner holes of the first bushing (2) and the second bushing (8) and the end face of the second bushing (8) in contact with the shoulder of the hollow shaft (6) are laser-clad with Stellite 12 alloy. If the second bushing (8) is made of high-nickel ductile iron, the corresponding surface does not need to be laser-clad. When heat transfer oil and water are used as the medium, the outer surface of the hollow shaft (6), the first bushing (2), and the end face of the second bushing (8) in contact with the shoulder of the hollow shaft (6) are laser-clad with Stellite 12 alloy. The inner hole of the bushing (2) and the second bushing (8) and the end face of the second bushing (8) in contact with the shoulder of the hollow shaft (6) are laser-clad with iron-based alloy. Since the working temperature is low when heat transfer oil or water is used as heat transfer medium, in order to solve the problem of high frictional resistance caused by high temperature dry friction between the hollow shaft (6) and the second bushing (8) at high temperature, or even the problem of foreign objects entering and causing vibration, the material of the second bushing (8) can be selected as ductile iron or copper alloy with a coefficient of expansion similar to or slightly higher than that of the base material, and the corresponding surface does not need to be laser-clad.

[0020] Preferably, the mating surfaces of the second metal-edged reinforcing sealing ring (4) and the hollow shaft (6) are made with the same structure, such as an inclined surface or other corresponding structure.

[0021] Preferably, the rotational friction between the second bushing (8) and the hollow shaft (6) is high-temperature dry friction. The inner cylindrical surface of the second bushing (8) is provided with grooves to store high-temperature solid lubricant and reduce the high-temperature rotational dry friction coefficient between the second bushing (8) and the hollow shaft (6).

[0022] The beneficial effects of this invention are:

[0023] (1) The present invention uses soft packing seal, which not only reduces costs but also provides reliable sealing. Online maintenance can be achieved without replacing any seals, ensuring the lifespan requirement of 25 to 30 years for solar thermal power plants;

[0024] (2) The planar rotary joint of the present invention can be used for flexible connection of high temperature molten salt tank at 560°C, filling the gap at home and abroad, solving the technical bottleneck for the development and commercial application of solar thermal power generation molten salt tank. At the same time, by using different sealing materials, it can also be used for flexible connection system of trough collectors with heat transfer oil and water as heat transfer medium at 430°C and below, replacing the imported ball joint used in heat transfer oil tank.

[0025] (3) The planar rotary joint of the present invention has a small rotational torque and operates smoothly and stably;

[0026] (4) Since a parabolic trough solar thermal power plant requires a large number of flexible connections (a 100MW parabolic trough solar thermal power plant with 360 circuits requires 2,800 planar rotary joints or more than 8,000 spherical joints), it will bring huge social and economic benefits. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the planar rotary joint provided in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of the housing 1 provided in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the first bushing 2 provided in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the structure of the first metal-edged wire-reinforced sealing ring 3 provided in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the structure of the second metal-edged wire-reinforced sealing ring 4 provided in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the sealing ring support 5 provided in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the structure of the hollow shaft 6 provided in an embodiment of the present invention;

[0034] Figure 8 This is a schematic diagram of the mechanism of the second bushing 8 provided in an embodiment of the present invention;

[0035] Figure 9 This is a schematic diagram of the structure of the threaded flange 11 provided in an embodiment of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figure 1As shown, the purpose of this invention is to provide a flexible connecting planar rotary joint for high-temperature trough solar collectors, comprising: a housing 1, a first bushing 2, four first metal-edged wire-reinforced sealing rings 3, two second metal-edged wire-reinforced sealing rings 4, a sealing ring support 5, a hollow shaft 6, a sealing ring pressure ring 7, a second bushing 8, two anti-rotation pins 9, an adjusting bolt 10, a threaded flange 11, an injectable soft filler 12, and three injection port sealing bolts 13;

[0038] The housing 1 is the base of the planar rotary joint and is used to install and fix other components. Three evenly distributed threaded holes are provided on the circumferential surface of the housing 1 as injection holes for injectable soft filler 12. They are also used to connect the check valve and the high-pressure injection gun to add injectable soft filler 12 during assembly and online maintenance. After adding injectable soft filler 12 at the required pressure, the injection port sealing bolt 13 is used to block the injection threaded port on the housing 1.

[0039] The present invention relates to an assembly method for a flexible connecting planar rotary joint for high-temperature trough solar collectors:

[0040] The bushing 2 is installed at the bottom of the inner cavity of the housing 1, and then a first metal-edged wire reinforced sealing ring 3, a second metal-edged wire reinforced sealing ring 4, a sealing ring support 5, a hollow shaft 6, a second metal-edged wire reinforced sealing ring 4, four first metal-edged wire reinforced sealing rings 3, a sealing ring pressure ring 7, a second bushing 8, two anti-rotation pins 9, and a threaded flange 11 are installed in sequence.

[0041] Pressure is applied to the second bushing 8 using an assembly tool and directly transmitted to the hollow shaft 6. Simultaneously, the pressure is transmitted to the four first metal-edged wire-reinforced sealing rings 3 and the two second metal-edged wire-reinforced sealing rings 4 through the sealing ring pressure ring 7 and the sealing ring support 5. After the second bushing 8 is pressed into place, the threaded flange 11 is rotated to the bottom, and then the adjusting bolt 10 is installed on the second bushing 8, with its end contacting the sealing ring pressure ring 7.

[0042] Then, the injection gun with the one-way valve is installed on the injection threaded hole of the housing 1, and the injectable soft filler 12 is injected according to the given pressure. After the injection is completed, the injection gun with the one-way valve is removed, and the sealing bolt 13 is installed through the injection port thread. After the sealing bolt 13 is tightened to the bottom, the assembly of the planar rotating head is completed.

[0043] The first set of sealing rings, consisting of a first metal-edged wire-reinforced sealing ring 3 and a second metal-edged wire-reinforced sealing ring 4 near the bottom of the housing 1, forms the first seal. The injectable soft filler 12 filling the sealing cavity forms the second seal, which is crucial for ensuring seal reliability and lifespan. The second set of sealing rings, consisting of three first metal-edged wire-reinforced sealing rings 3 and one second metal-edged wire-reinforced sealing ring 4 near the end of the housing 1, is also an important third seal. The increased number of sealing rings in the second set allows for easy increase of the sealing ring compression via the adjusting bolt 10 in case of long-term leakage, enabling reliable sealing during online maintenance. Furthermore, the injectable soft filler 12 can be injected again to further ensure a reliable seal.

[0044] During the installation of the solar collector, the outer end of the hollow shaft 6 is welded to the rotatable moving pipeline system (including solar collector tubes, tees, splined cross couplings, and swing compensation bellows, etc.), and one end of the shell 1 is welded to the static pipeline.

[0045] The working principle of the flexible connecting planar rotary joint for high-temperature trough solar collectors of the present invention:

[0046] As the solar collector rotates to track the sun, the pressurized heat transfer medium (maximum 4 MPa) in the heated collector tubes is heated to a high temperature. This heat flows through the outer end of the hollow shaft 6 of the rotating head and out through the outer end of the casing 1 into the static pipe. Simultaneously, the pressurized, high-temperature heat transfer medium acts on the cross-section of the hollow shaft 6, generating a thrust towards the threaded flange 11. This thrust also acts on the first set of sealing rings towards the threaded flange 11. The first set of sealing rings, the injectable soft packing 12, and the second set of sealing rings form a static seal with the casing 1 and a dynamic seal with the rotating hollow shaft 6, preventing leakage of the high-temperature, pressurized heat transfer medium from the casing to the outside.

[0047] The first bushing 2 and the second bushing 8 provide centering and rotational support for the hollow shaft 6. At the same time, the second bushing 8 acts as a thrust plate, bearing the outward thrust of the hollow shaft 6. The first bushing 2 and the hollow shaft 6 are a high-temperature wet rotational friction pair, and the second bushing 8 and the hollow shaft 6 are a high-temperature dry rotational friction pair. Therefore, the structure, material, or laser cladding surface treatment of the inner hole surface and the end face that contacts the shoulder of the hollow shaft 6 of the second bushing 8 are crucial to the friction force, friction torque, and service life.

[0048] The two anti-rotation pins 9 are to prevent the second bushing 8 from rotating under the dry friction torque caused by the rotation of the hollow shaft 6. The sealing ring support 5 is provided between the first set of sealing rings and the second set of sealing rings to transmit the compression force of the sealing rings. The sealing ring support 5 is provided with several round holes or elongated holes evenly arranged in the radial direction so that the injectable soft filler 12 can fill the entire sealing cavity.

[0049] The adjusting bolt 10 is used to address leaks caused by wear and consumption of the sealing material after long-term online maintenance. This includes: increasing the compression of the first metal-edged reinforcing sealing ring 3 and the second metal-edged reinforcing sealing ring 4 by adjusting the adjusting bolt 10 to eliminate leaks; or injecting injectable soft filler 12 to achieve further reliable sealing.

[0050] The housing 1 has three injection ports 13 evenly distributed on it. The injection ports 13 are threaded injection ports and are used to add the injectable soft filler during assembly and online maintenance.

[0051] In a preferred embodiment, the dynamic sealing surface of the hollow shaft 6 is provided with a composite structure of an inclined surface + one or more spherical surfaces + an inclined surface, so that the second metal-edged wire reinforced sealing ring 4 and the hollow shaft 6 are sealed by an inclined surface, and the injectable soft filler 12 and the hollow shaft 6 are sealed by an inclined surface + spherical surface, thereby ensuring the reliability of the dynamic seal under the pressure of the working medium; at the same time, the greater the working pressure of the pressurized medium, the greater the pressure on the first set of sealing rings and the hollow shaft 6 to move towards the end, and the sealing performance will also be improved.

[0052] In a preferred embodiment, the sealing ring support 5 is provided with uniformly distributed holes or elongated holes, so that the injectable soft packing fills the entire injectable soft packing sealing cavity. At the same time, through assembly pressure, the sealing ring support 5 compresses both the first set of sealing rings and the second set of sealing rings, thereby achieving a seal between the working medium and the injectable soft packing.

[0053] In a preferred embodiment, when high-temperature molten salt is used as the medium, the first metal-edged wire-reinforced sealing ring 3 and the second metal-edged wire-reinforced sealing ring 4 are vermiculite sealing rings reinforced with metal edging and wire; when heat transfer oil and water are used as the medium, the first metal-edged wire-reinforced sealing ring 3 and the second metal-edged wire-reinforced sealing ring 4 are flexible graphite sealing rings reinforced with metal edging and wire, so as to improve the rigidity, erosion resistance and sealing performance of the sealing rings.

[0054] Firstly, the choice of metal-edged reinforced vermiculite sealing rings for high-temperature molten salt media stems from vermiculite's excellent high-temperature stability and strong resistance to oxidation and corrosion. High-temperature molten salt tanks (such as those using binary nitrates) have a maximum operating temperature of 560℃ and exhibit strong high-temperature oxidative corrosion. Expanded vermiculite's good sealing performance and high-temperature stability make it a preferred soft sealing material for high-temperature molten salt media. For trough-type solar collectors using heat transfer oil and water as the heat transfer medium, the operating temperature is lower (below 430℃), resulting in little or no oxidation and corrosion. Flexible graphite or vermicular expanded graphite possesses excellent elasticity and sealing performance, along with a very low coefficient of friction, making it an excellent soft sealing material in various industries. The maximum operating temperature of flexible graphite or vermicular expanded graphite in a vacuum or inert gas environment can reach approximately 1200℃, and in atmospheric conditions it can reach approximately 450℃. Therefore, flexible graphite or vermicular expanded graphite is an ideal soft sealing material for planar rotating heads using heat transfer oil and water as the heat transfer medium.

[0055] In a preferred embodiment, all metal components except the sealing material are made of the same metal material to ensure a uniform coefficient of thermal expansion, which is crucial for the reliable operation of the planar rotary joint at high temperatures. The metal components, excluding the sealing material, include the housing 1, the hollow shaft 6, the first bushing 2, the sealing ring support 5, the sealing ring pressure ring 7, and the threaded flange 11. The second bushing 8 can be made of the same material and undergo appropriate surface laser cladding treatment, or it can be made of high-nickel ductile iron with a slightly larger coefficient of thermal expansion. For planar rotary heads using heat transfer oil or water as the heat transfer medium, the second bushing 8 for dry friction can be made of the same material and undergo appropriate surface laser cladding treatment. Due to the lower operating temperature, to increase friction life, reduce friction torque, and reduce friction vibration, ductile iron or copper alloy can also be selected depending on the temperature, and the corresponding surface does not require laser cladding treatment.

[0056] As a preferred embodiment, the sealing ring is reinforced with metal edging and metal wire to increase its rigidity and erosion resistance.

[0057] As a preferred embodiment, when the high-temperature molten salt medium is used, the metal material is stainless steel (e.g., 347H) or other high-temperature alloy materials that are resistant to high-temperature oxidation, high-temperature creep, and have good weldability; when the heat transfer oil or water is used as the medium, the metal material is selected according to the temperature, either austenitic stainless steel or high-quality carbon steel (e.g., 20# steel, 25# steel, etc.) with good weldability that is compatible with the working temperature or heat-resistant alloy steel (e.g., 20CrMo, etc.).

[0058] In a preferred embodiment, when the high-temperature molten salt medium is used, the outer surface of the hollow shaft 6 is laser-clad with Stellite 6 / 6A alloy, and the end faces of the contact portions between the inner holes of the first bushing 2 and the second bushing 8 and the shoulder of the hollow shaft 6 are laser-clad with Stellite 12 alloy to ensure high-temperature hardness, matching hardness of the friction pair, low coefficient of friction of the friction pair, wear resistance, anti-adhesive friction, anti-adhesion of sealing filler, and scratch resistance. When the heat transfer oil and water are used as the medium, the sealing surface of the hollow shaft 6 and the mating surfaces of the hollow shaft 6 with the first bushing 2 and the second bushing 8 are laser-clad with iron-based alloys. When the second bushing is selected from high-nickel ductile iron, ductile iron, or copper alloy, the surface is not laser-clad.

[0059] In a preferred embodiment, the rotational friction between the second bushing 8 and the hollow shaft 6 is high-temperature dry friction. The inner cylindrical surface of the second bushing 8 is provided with grooves to store high-temperature solid lubricant and reduce the coefficient of dry friction.

[0060] In a preferred embodiment, the first bushing 2 is made of the same material as the base metal and laser clad to ensure the hardness of the mating surface at high temperatures, increase corrosion resistance, and prevent foreign matter in the heat-conducting medium from damaging the moving mating surface.

[0061] like Figure 2 As shown, the housing 1 is the base of the planar rotary joint, made of 347H stainless steel, and is used to install and fix other components. Three evenly distributed injection thread holes are provided on the circumferential surface for connecting the check valve and the high-pressure injection gun to add injectable soft filler during assembly and online maintenance. After adding the injectable soft filler, the injection port is blocked with the injection port sealing bolt 13.

[0062] like Figure 3 As shown, the first bushing 2 is made of 347H stainless steel, and its inner hole is laser-clad with Stellite 12 high-temperature alloy. It is used to radially position the hollow shaft 6 and bear radial force and bending moment.

[0063] like Figure 4 As shown, the first metal-edged, wire-reinforced sealing ring 3 is a vermiculite sealing ring reinforced with metal edging and metal wire. The outer cylindrical surface fits tightly with the shell to achieve static sealing, and the inner cylindrical surface fits tightly with the outer cylindrical surface of the hollow shaft 6 to achieve dynamic sealing. In this embodiment, the metal edging structure of the first metal-edged, wire-reinforced sealing ring 3 is rotated into an L-shape to reduce frictional torque.

[0064] like Figure 5As shown, the second metal-edged and wire-reinforced sealing ring 4 is a vermiculite sealing ring reinforced by metal edging and metal wire. The outer cylindrical surface fits tightly with the shell to achieve static sealing, and the inner conical surface fits with the outer conical surface of the hollow shaft 6 to achieve reliable dynamic sealing.

[0065] like Figure 6 As shown, the sealing ring support 5 is made of 347H stainless steel, with 6 round holes or elongated holes evenly distributed in the circumferential direction to ensure the flow of injectable soft filler 12 and to fill the entire filler sealing cavity.

[0066] like Figure 7 As shown, the hollow shaft 6 is made of 347H stainless steel, with its outer surface laser-clad with Stellite 6 / 6A high-temperature alloy. The sealing surface is designed with a slope + two spherical surfaces + a slope structure. This ensures that the second metal-edged wire-reinforced sealing ring 4 and the hollow shaft 6 are sealed with a slope, and the injectable soft filler sealing cavity and the hollow shaft 6 are sealed with a slope + spherical surface, thus guaranteeing the reliability of the dynamic seal. Furthermore, the greater the working pressure of the medium, the greater the thrust from the bottom to the end of the housing 1 on the first metal-edged wire-reinforced sealing ring 3, the second metal-edged wire-reinforced sealing ring 4, and the hollow shaft 6, thereby enhancing the dynamic sealing performance of the second metal-edged wire-reinforced sealing ring 4 and the injectable soft filler 12 on the hollow shaft 6.

[0067] like Figure 8 As shown, the second bushing 8 is made of 347H stainless steel. Since its function is not only to radially position the hollow shaft 6 and bear radial force and bending moment, but also to act as a thrust plate, the inner bore of the second bushing 8 and the contact surface with the shoulder of the hollow shaft 6 are laser-clad with Stellite 12 high-temperature alloy. Because the rotational friction between the second bushing 8 and the hollow shaft 6 is high-temperature dry friction, grooves are provided on the inner cylindrical surface to store high-temperature solid lubricant and reduce the coefficient of dry friction.

[0068] like Figure 9 As shown, the threaded flange 11 is made of 347H stainless steel, and its outer cylindrical surface has 6 flat surfaces for tightening the threaded flange 11.

[0069] In this embodiment, the sealing ring pressure ring 7 is made of 347H stainless steel. Therefore, the materials of the parts that affect sealing and mechanical rotation are all the same 347H stainless steel, which ensures that the materials have the same coefficient of thermal expansion, good resistance to high temperature oxidation and corrosion, and good resistance to high temperature creep strength under high temperature molten salt medium conditions.

[0070] In this embodiment, when high-temperature molten salt is used as the medium, the main components of the injectable soft filler are expanded vermiculite microparticles and mineral fibers.

[0071] In this embodiment, the inner hole of the first bushing 2, the inner hole of the second bushing 8, and the end face that contacts the shoulder of the hollow shaft 6 are all laser-clad with 12 high-temperature alloy. The outer surface of the hollow shaft 6 is clad with Stellite 6 / 6A high-temperature alloy, which ensures the fit of the high and low hardness friction pair under high temperature and high hardness. It has a low coefficient of friction, anti-adhesion friction and anti-oxidation properties at high temperature. At the same time, the surface cladding layer of the hollow shaft 6 has good anti-adhesion properties of soft sealing materials and anti-scratch properties, thereby ensuring the reliability of mechanical rotation, low rotational torque and high sealing performance.

[0072] In this embodiment, during assembly, the first bushing 2 is first installed at the bottom of the inner cavity of the housing 1. Then, the first set of sealing rings and the second set of sealing rings are installed in sequence. The sealing ring pressure ring 7 is pressed into position with the aid of an assembly tool, and the threaded flange 11 is tightened to ensure tight contact with the end face of the first bushing 2. Then, the high-pressure injection gun with a one-way valve is connected through the injection thread hole on the housing 1, and the injectable soft filler is added into the injectable soft filler sealing cavity according to the required injection pressure. Then, the one-way valve and the high-pressure injection gun are removed, and the injection port bolt 131 on the injection port 13 is tightened to the injection thread hole on the housing 1. Finally, the adjusting bolt 10 is installed, with its end contacting the sealing ring support 5.

[0073] In this embodiment, when the sealing ring pressure ring 7 is pressed into place during assembly, the pressure is directly transmitted to the hollow shaft (6). At the same time, the pressure is transmitted between the first set of sealing rings and the second set of sealing rings through the sealing ring pressure ring 7 and the sealing ring support 5, so that both sets of sealing rings are compressed. The first metal-edged metal wire reinforced sealing ring 3 and the second metal-edged metal wire reinforced sealing ring 4 are in close contact with the inner cavity of the housing 1 and the circumferential surface of the hollow shaft 6, so as to achieve static sealing of the housing 1 and dynamic sealing of the hollow shaft 6. Then, the injectable soft filler 12 is sealed in the injectable soft filler sealing cavity.

[0074] In this embodiment, the sealing ring support 5, the sealing ring pressure ring 7, and the threaded flange 11 are all made of 347H stainless steel, which ensures the consistency of the material expansion coefficient at high temperature and high resistance to oxidation, corrosion and creep. The anti-rotation pin 9 is used to prevent the hollow shaft (6) from rotating under the action of the high temperature dry friction torque generated on the second bushing 8 when it rotates.

[0075] In this embodiment, the adjusting bolt 10 is made of a high-temperature alloy to ensure the strength and performance of the bolt at high temperatures. Its function is to increase the compression of the first metal-edged reinforcing sealing ring 3 and the second metal-edged reinforcing sealing ring 4 by adjusting the bolt 10 if leakage occurs due to wear and consumption of the sealing material after long-term operation, thus enabling online maintenance.

[0076] In this embodiment, if leakage occurs due to wear and consumption of the sealing material after long-term operation, online maintenance can be achieved by adding injectable soft filler.

[0077] In this embodiment, the metal material used in the planar rotary joint, the material of the sealing ring, the structure of the sealing ring, the number and arrangement of the sealing rings, and the main components of the injectable soft filler can be changed according to different heat transfer media, operating pressure, and temperature requirements, all of which are within the protection scope of this invention.

[0078] The apparatus and methods disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments. For relevant details, please refer to the method section.

[0079] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flexible connecting planar rotary joint for high-temperature trough solar collectors, characterized in that, include: The components include: housing (1), first bushing (2), four first metal-edged wire-reinforced sealing rings (3), two second metal-edged wire-reinforced sealing rings (4), sealing ring support (5), hollow shaft (6), sealing ring pressure ring (7), second bushing (8), two anti-rotation pins (9), adjusting bolt (10), threaded flange (11), injectable soft filler (12), and three injection port plugging bolts (13). The housing (1) is the base of the planar rotary joint and is used to install and fix other components. Three injection thread ports are evenly distributed on the housing (1). During assembly and online maintenance, the injectable soft filler (12) is added through the three injection thread ports. After the injectable soft filler (12) is added to form a sealing material, the three injection port sealing bolts (13) are used to seal the three injection thread ports respectively. The first bushing (2) is disposed at the bottom of the inner cavity of the housing (1); A first set of sealing rings and a second set of sealing rings are respectively provided on both sides of the injectable soft filler (12); the first set of sealing rings is composed of one or more first metal-edged wire reinforced sealing rings (3) and one or more second metal-edged wire reinforced sealing rings (4); the second set of sealing rings is composed of another or more first metal-edged wire reinforced sealing rings (3) and another or more second metal-edged wire reinforced sealing rings (4); the two sets of sealing rings are located on both sides of the injectable soft filler (12), and a sealing ring support (5) is provided between the two sets of sealing rings. The two sets of sealing rings are connected to the housing (1). The hollow shaft (6) and the sealing ring support (5) form a sealing cavity for injectable soft filler (12). During assembly, pressure is applied to the second bushing (8) using a tool. The second bushing (8) directly applies pressure to the hollow shaft (6), and at the same time, pressure is transmitted to the second set of sealing rings and the first set of sealing rings through the sealing ring pressure ring (7) and the sealing ring support (5), so that the two sets of sealing rings are reliably compressed to ensure sealing performance. The sealing ring support (5) is provided with several round holes or elongated holes evenly arranged radially. The anti-rotation pin (9) is used to prevent the first bushing (2) from rotating under the action of the high temperature dry friction force generated by the rotation of the hollow shaft (6). The adjusting bolt (10) is used for online maintenance of leaks caused by wear and consumption of the sealing material after long-term operation, including: increasing the compression of the first metal-edged wire reinforced sealing ring (3) and the second metal-edged wire reinforced sealing ring (4) by adjusting the adjusting bolt (10) to eliminate the leak; forming a sealing cavity for injectable soft filler (12) between the two sets of sealing rings and the housing (1), the hollow shaft (6) and the sealing ring support (5); The threaded flange (11) is used for axial fixation of all components installed in the housing (1), and the adjusting bolt (10) is installed on the second bushing (8); wherein, pressure is applied to the second bushing (8) using an assembly tool and transmitted to the hollow shaft (6), and at the same time transmitted to the four first metal-edged metal wire reinforced sealing rings (3) and two second metal-edged metal wire reinforced sealing rings (4) through the sealing ring pressure ring (7) and the sealing ring support (5), then the threaded flange (11) is rotated to the bottom, and the adjusting bolt (10) is installed on the second bushing (8) so that its end contacts the sealing ring pressure ring (7); During assembly, injectable soft filler (12) is injected into the injectable soft filler sealing cavity according to the required pressure. The injectable soft filler (12) fills the entire sealing cavity. After long-term operation, leakage caused by the wear and consumption of the sealing material can be repaired online by adding the injectable soft filler again. The first bushing (2) and the second bushing (8) serve as supporting components for the hollow shaft (6) and form a high-temperature rotating friction pair with the hollow shaft (6). At the same time, the second bushing (8) also acts as a thrust plate, bearing the outward axial thrust applied to the hollow shaft (6) under the working medium pressure.

2. The flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 1, characterized in that, The dynamic sealing surface of the hollow shaft (6) is provided with a composite structure of inclined surface + one or more spherical surfaces + inclined surface, so that the second metal-edged metal wire reinforced sealing ring (4) and the hollow shaft (6) are sealed by inclined surface, and the sealing cavity of the injectable soft filler and the hollow shaft (6) are sealed by inclined surface + spherical surface; or the dynamic sealing surface of the hollow shaft (6) is a curved surface structure such as a full inclined surface structure, a full spherical surface structure or an elliptical structure to increase sealing performance.

3. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 2, characterized in that, The sealing ring support (5) is provided with evenly distributed round holes or elongated holes, so that the injectable soft filler (12) fills the entire injectable soft filler sealing cavity.

4. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 3, characterized in that, For the case where high-temperature molten salt is used as the medium, the first metal-edged wire-reinforced sealing ring (3) and the second metal-edged wire-reinforced sealing ring (4) are vermiculite sealing rings reinforced with metal edging and wire. For the case where heat transfer oil and water are used as the medium, the first metal-edged wire-reinforced sealing ring (3) and the second metal-edged wire-reinforced sealing ring (4) are flexible graphite sealing rings reinforced with metal edging and wire. Metal edging and wire reinforcement are used to improve the rigidity, erosion resistance and long-term sealing performance of the sealing ring. The metal edging structure of the first metal-edged wire-reinforced sealing ring (3) is an L-shaped metal edging or a U-shaped metal edging. The sealing performance of the U-shaped metal edging is better than that of the L-shaped metal edging, and the rotational torque of the U-shaped metal edging is slightly greater than that of the L-shaped metal edging.

5. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 4, characterized in that, When high-temperature molten salt is used as the medium, the injectable soft filler (12) is composed of expanded vermiculite microparticles and mineral fibers; when heat transfer oil and water are used as the medium, the injectable soft filler (12) is composed of worm-shaped expanded graphite particles and graphite / carbon fiber.

6. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 5, characterized in that, All metal parts other than the sealing material are made of the same metal material to prevent dimensional fit problems caused by different coefficients of thermal expansion at high temperatures; wherein, the metal parts other than the sealing material include the housing (1), the hollow shaft (6), the first bushing (2), the sealing ring support (5), the sealing ring pressure ring (7), the first bushing (2) and the threaded flange (11), and the second bushing (8) are made of the same material or different metal materials with similar or slightly larger coefficients of thermal expansion and good high-temperature dry friction performance.

7. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 6, characterized in that, When high-temperature molten salt is used as the medium, the metal material is stainless steel or a high-temperature alloy material that is resistant to high-temperature oxidation, high-temperature creep and has good weldability. The second bushing (8) is made of high-nickel ductile iron with a slightly larger coefficient of expansion. When heat transfer oil or water is used as the medium, the metal material is made of austenitic stainless steel or high-quality carbon steel or heat-resistant alloy steel with good weldability that is compatible with the working temperature. Since the working temperature is low when heat transfer oil and water are used as heat transfer media, the material of the second bushing (8) can be made of ductile iron or copper alloy with a coefficient of expansion close to or slightly larger than the temperature to reduce the friction force and friction torque of high-temperature dry friction. Since the first bushing is in direct contact with the medium, it is made of the same material as the base material and the surface is treated with laser cladding to improve corrosion resistance and prevent impurities in the medium from damaging the dynamic mating surface.

8. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 7, characterized in that, When high-temperature molten salt is used as the medium, the outer surface of the hollow shaft (6) is laser-clad with Stellite 6 / 6A alloy, and the inner holes of the first bushing (2) and the second bushing (8) and the end face of the second bushing (8) in contact with the shoulder of the hollow shaft (6) are laser-clad with Stellite 12 alloy. If the material of the second bushing (8) is high-nickel ductile iron, the corresponding surface does not need to be laser-clad. When heat transfer oil and water are used as the medium, the outer surface of the hollow shaft (6), the inner holes of the first bushing (2) and the second bushing (8) and the end face of the second bushing (8) in contact with the shoulder of the hollow shaft (6) are laser-clad with iron-based alloy. Since the working temperature is low when heat transfer oil or water is used as the heat transfer medium, the material of the second bushing (8) is selected to be ductile iron or copper alloy with a coefficient of thermal expansion similar to or slightly higher than that of the base material, and the corresponding surface does not need to be laser-clad.

9. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 2, characterized in that, The mating surfaces of the second metal-edged metal wire reinforced sealing ring (4) and the hollow shaft (6) are made to have the same structure during pressing.

10. A flexible connecting planar rotary joint for a high-temperature trough solar collector according to claim 9, characterized in that, The inner cylindrical surface of the second bushing (8) is provided with grooves to store high-temperature solid lubricant in order to reduce the high-temperature rotational dry friction coefficient between the second bushing (8) and the hollow shaft (6).

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