Superconducting cable termination conductor connection structure

Abstract

The application provides a superconducting cable terminal conductor connecting structure, which comprises a terminal cryogenic container and a superconducting cable, the terminal cryogenic container comprises a container body, a first liquid nitrogen cavity, a cable interface and a container flange, the superconducting cable comprises a cable core body, a cable heat preservation pipe, a second liquid nitrogen cavity and a cable flange, the container flange and the cable flange are fixedly connected, and a first sealing ring is arranged between the container flange and the cable flange, the first sealing ring comprises a hollow support framework, a metal sealing layer fixedly covered on the outer periphery of the support framework and a filling layer filled in the support framework, the hardness of the support framework is greater than the hardness of the metal sealing layer and the hardness of the filling layer, the support framework has an opening part, and the radial thickness of the support framework gradually decreases from the middle to both ends along the circumferential direction. When the first sealing ring is subjected to pressure, the metal sealing layer and the support framework are easy to deform, so that defects on the sealing surface are effectively filled, thickness deviation caused by non-parallel sealing surfaces is compensated to a certain extent, and the sealing effect is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of superconducting cable system technology, and in particular to a superconducting cable terminal conductor connection structure. Background Technology

[0002] Superconducting cables are a type of cable made using superconductors. Typically, a superconducting cable includes a cable core, an insulation tube surrounding the cable core, and flowing liquid nitrogen filling the space between the cable core and the insulation tube. The flowing liquid nitrogen serves as the cooling medium for the superconducting cable, maintaining the low-temperature operating environment of the superconductor.

[0003] At the end of the superconducting cable system, a cryogenic container and a current lead are installed. The cryogenic container contains liquid nitrogen, and one end of the current lead extends into the cryogenic container and is connected to the superconducting cable that extends into the cryogenic container, so as to realize the connection between the superconducting cable and the external power grid. In addition, the cryogenic container and the insulation pipe of the superconducting cable are fixedly connected, and a sealing ring is provided at the connection to prevent liquid nitrogen leakage.

[0004] Currently, the sealing between cryogenic containers and the insulation pipes of superconducting cables typically employs polymer sealing rings, CF flange seals, indium wire seals, or rubber sealing rings. However, polymer sealing rings require high cleanliness and parallelism between the sealing surfaces, making them difficult to achieve. CF flange seals use stainless steel knife edges in conjunction with copper sealing rings to achieve a sealing effect, but their processing precision is high, resulting in high costs. Indium wire sealing materials are too soft, making installation difficult and impractical. Rubber sealing rings provide excellent sealing performance at room temperature, but lose elasticity at low temperatures, making the seal between the cryogenic container and the insulation pipe of the superconducting cable prone to failure.

[0005] In addition, the current leads at the ends of superconducting cables are usually made of a single metal material, and the end that extends into the cryogenic container operates in a cryogenic liquid nitrogen environment, resulting in large Joule heat loss and failing to achieve energy-saving effects. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a superconducting cable terminal conductor connection structure with good low-temperature sealing effect and to avoid liquid nitrogen leakage.

[0007] To achieve the above objectives, the present invention provides a superconducting cable termination conductor connection structure, including a terminal cryogenic container and a superconducting cable. The terminal cryogenic container includes a container body, a first liquid nitrogen chamber formed within the container body, a cable interface formed on the container body and communicating with the first liquid nitrogen chamber, and a container flange fixed at the cable interface. The superconducting cable includes a cable core, a cable insulation tube sleeved around the outer periphery of the cable core, a second liquid nitrogen chamber formed between the cable core and the cable insulation tube, and a cable flange fixed at the end of the cable insulation tube. One end of the cable core extends into the first liquid nitrogen chamber from the cable interface, and the first liquid nitrogen chamber communicates with the second liquid nitrogen chamber. The cavity is connected via a cable interface, and the container flange and the cable flange are fixedly connected. The superconducting cable terminal conductor connection structure also includes a first sealing ring disposed at the junction of the container flange and the cable flange. The first sealing ring includes a hollow support frame, a metal sealing layer fixedly covering the outer periphery of the support frame, and a filling layer filled inside the support frame. The hardness of the support frame is greater than the hardness of the metal sealing layer and the hardness of the filling layer. The support frame has an opening, and the radial thickness of the support frame gradually decreases from the middle to both ends along its circumference, so that the support frame has a thin part at the opening. The opening of the first sealing ring faces the first liquid nitrogen cavity.

[0008] Furthermore, the material of the supporting frame is stainless steel or copper, and the material of the metal sealing layer is tin, lead, indium, or a soft alloy.

[0009] Furthermore, the metal sealing layer and the filling layer are made of the same material.

[0010] Furthermore, the cable insulation pipe is a single-layer pipe.

[0011] Furthermore, the cable insulation pipe is a double-layer pipe, which includes an inner pipe body, an outer pipe body, and a vacuum cavity formed between the inner pipe body and the outer pipe body, and the cable core is inserted into the inner pipe body of the cable insulation pipe.

[0012] Furthermore, the terminal cryogenic container also includes a port opened on one side of the first liquid nitrogen chamber, a port flange fixed at the port, and an end plate. The end plate is fixedly connected to the port flange and the end plate blocks the port. A second sealing ring is provided at the junction of the end plate and the port flange. The structure of the second sealing ring is the same as that of the first sealing ring, and the opening of the second sealing ring faces the first liquid nitrogen chamber.

[0013] Furthermore, the superconducting cable terminal conductor connection structure also includes a current lead, one end of which extends into the first liquid nitrogen chamber and is connected to the cable core located inside the first liquid nitrogen chamber.

[0014] Furthermore, the current lead includes a lead body section and a lead superconducting composite section. At least a portion of the lead superconducting composite section is located in the first liquid nitrogen cavity. The lead superconducting composite section includes, from the inside out, a conductor inner core, a superconducting layer, and a conductor outer jacket. The two ends of the conductor inner core are fixedly connected to the lead body section and the cable core, respectively.

[0015] Furthermore, the superconducting layer is made of Bscco superconductor.

[0016] Furthermore, the lead body segment and the conductor core are an integral structure, and the materials of the lead body segment and the conductor core are copper, aluminum, or an alloy.

[0017] As described above, the superconducting cable terminal conductor connection structure of the present invention has the following beneficial effects:

[0018] This application, by setting the first sealing ring to cover a softer metal sealing layer outside a relatively rigid support frame, is not only easy to install but also highly adaptable to the sealing surfaces of container flanges and cable flanges. In particular, when the first sealing ring is subjected to pressure, the softer metal sealing layer and the support frame with openings and thickness variations are easily deformed, thereby effectively filling defects on the sealing surface and compensating for a certain degree of thickness deviation caused by non-parallel sealing surfaces. Ultimately, this better ensures the sealing effect in low-temperature environments and prevents liquid nitrogen leakage. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the superconducting cable terminal conductor connection structure in Embodiment 1 of this application.

[0020] Figure 2 for Figure 1 Enlarged view of circle A.

[0021] Figure 3 This is a schematic diagram of Embodiment 2 of the superconducting cable terminal conductor connection structure in this application.

[0022] Figure 4 This is a schematic diagram of the structure of the first and second sealing rings in this application. The diagram is a radial sectional view.

[0023] Figure 5 This is a schematic diagram of the current lead structure in this application, and the diagram is an axial sectional view.

[0024] Figure 6 for Figure 5 BB-direction sectional view. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0026] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0027] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0028] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0029] like Figure 1 and Figure 2 Or such as Figure 3As shown, the superconducting cable terminal conductor connection structure involved in this application includes a terminal cryogenic container 10 and a superconducting cable 20. The terminal cryogenic container 10 includes a container body 30, a first liquid nitrogen chamber 31 formed within the container body 30, a cable interface 32 opened on the container body 30 and communicating with the first liquid nitrogen chamber 31, and a container flange 33 fixed at the cable interface 32. The first liquid nitrogen chamber 31 contains liquid nitrogen. The superconducting cable 20 includes a cable core 21, a cable insulation tube 22 sleeved around the cable core 21, a second liquid nitrogen chamber 23 formed between the cable core 21 and the cable insulation tube 22, and a cable flange 24 fixed at the end of the cable insulation tube 22. One end of the cable core 21 extends into the first liquid nitrogen chamber 31 from the cable interface 32. The first liquid nitrogen chamber 31 and the second liquid nitrogen chamber 23 are connected through the cable interface 32. Liquid nitrogen in the terminal cryogenic container 10 flows into the second liquid nitrogen chamber 23 of the superconducting cable 20 to maintain the cryogenic environment required for the operation of the cable core 21. The container flange 33 and the cable flange 24 are fixedly connected by several bolts, thereby fixing the superconducting cable 20 and the terminal cryogenic container 10.

[0030] Furthermore, such as Figure 1 and Figure 2 Or such as Figure 3 As shown, the end face of the container flange 33 facing the cable flange 24 and the end face of the cable flange 24 facing the container flange 33 are both sealing surfaces. A first sealing ring 40 is provided at the junction of the container flange 33 and the cable flange 24. The sealing surface and the first sealing ring 40 ensure the sealing between the container flange 33 and the cable flange 24, preventing liquid nitrogen from leaking out from the junction of the container flange 33 and the cable flange 24.

[0031] In particular, such as Figure 2 and Figure 4 As shown, the first sealing ring 40 includes a hollow support frame 41, a metal sealing layer 42 fixedly covering the outer periphery of the support frame 41, and a filling layer 43 filled within the support frame 41. The hardness of the support frame 41 is greater than the hardness of the metal sealing layer 42 and the filling layer 43. In the circumferential direction of the support frame 41, the support frame 41 has an opening 411, and the radial thickness of the support frame 41 gradually decreases from the middle to both ends along its circumference. That is, the support frame 41 has the maximum radial thickness at its circumferential middle position and the minimum radial thickness at the ends on both sides of the opening 411, thus the support frame 41 has a thin portion 412 on both sides of the opening 411. Furthermore, the opening 411 of the first sealing ring 40 faces the first liquid nitrogen chamber 31 with higher pressure.

[0032] In the superconducting cable terminal conductor connection structure involved in this application, the first sealing ring 40 is a composite layer structure, using a relatively rigid support frame 41 as support. The opening 411, the thin portion 412, and the relatively soft filling layer 43 of the support frame 41 make it easy for the support frame 41 to deform at the opening 411 when under pressure, which is conducive to deformation. The metal sealing layer 42 fixedly covering the outside of the support frame 41 is relatively soft and easily deformed under pressure. The relatively soft inner filling layer 43 is not only conducive to the deformation of the support frame 41, but also ensures that there are no air gaps inside the support frame 41, which facilitates the subsequent vacuuming. Therefore, when the first sealing ring 40 is subjected to pressure, the relatively soft metal sealing layer 42, as well as the support frame 41 with its opening 411 and thickness variation, are easily deformed, thereby effectively filling the defects on the sealing surface, compensating for a certain degree of thickness deviation caused by the non-parallelism of the sealing surface, and ultimately ensuring a better sealing effect in low-temperature environments, avoiding liquid nitrogen leakage. Meanwhile, the first sealing ring 40 has a simple and easy-to-implement structure, is easy to install, and has strong adaptability to the sealing surfaces of the container flange 33 and the cable flange 24, which helps to reduce costs.

[0033] Preferably, such as Figure 2 As shown, the sealing surface of the container flange 33 is provided with a first mounting groove 331 facing the cable flange 24, and the first sealing ring 40 is accommodated in the first mounting groove 331. The structure is simple and easy to implement.

[0034] Furthermore, the cross-sectional shape of the first sealing ring 40 is customized according to the sealing structure, and can be circular, square, or other shapes. The materials of the support frame 41, the metal sealing layer 42, and the filling layer 43 are selected according to the material of the sealing surface. If the material of the support frame 41 is stainless steel, copper, or other alloys with a hardness lower than that of the sealing surface material, then the support frame 41 is a hard metal material. The metal sealing layer 42 and the filling layer 43 can be made of the same material or different materials; in this embodiment, the metal sealing layer 42 and the filling layer 43 are preferably made of the same material, both of which are tin, lead, indium, or soft alloys. Soft alloys refer to softer alloy materials, so the metal sealing layer 42 and the filling layer 43 are both soft metal materials. When the materials of the inner and outer components of the support frame 41 are consistent, it is more conducive to the stability of the shape of the soft metal material.

[0035] Furthermore, in the superconducting cable 20, the cable insulation pipe 22 is a single-layer pipe or a double-layer pipe; when the cable insulation pipe 22 is a double-layer pipe, the double-layer pipe includes an inner pipe body, an outer pipe body, and a vacuum chamber formed between the inner pipe body and the outer pipe body. The cable core 21 is inserted into the inner pipe body of the cable insulation pipe 22. By evacuating the vacuum chamber, the cold insulation effect is improved.

[0036] Furthermore, the container body 30 of the terminal cryogenic container 10 can be... Figure 1The end-closed structure shown can also be Figure 3 The end-opening structure is shown. When the container body 30 has an end-opening structure, as shown... Figure 3 As shown, the terminal cryogenic container 10 also includes a port 34 opened on one side of the first liquid nitrogen chamber 31, a port flange 35 fixed at the port 34, and an end plate 50. The port 34 facilitates the maintenance of the container body 30. The end plate 50 is fixedly connected to the port flange 35 by several bolts, and the end plate 50 seals the port 34. The end face of the end plate 50 facing the port flange 35 and the end face of the port flange 35 facing the end plate 50 are both sealing surfaces, and a second sealing ring 60 is provided at the junction of the end plate 50 and the port flange 35. The structure of the second sealing ring 60 is the same as that of the first sealing ring 40, and the opening 411 of the second sealing ring 60 faces the first liquid nitrogen chamber 31 with higher pressure. The second sealing ring 60 also adopts a composite layer structure to prevent liquid nitrogen from leaking out between the end plate 50 and the port flange 35. Preferably, a second mounting groove 351 facing the end plate 50 is provided on the sealing surface of the port flange 35, and the second sealing ring 60 is accommodated in the second mounting groove 351, which is simple and easy to implement.

[0037] Furthermore, such as Figure 1 or Figure 3 As shown, the superconducting cable terminal conductor connection structure also includes a current lead 70. One end of the current lead 70 extends into the first liquid nitrogen chamber 31 and is connected to the cable core 21 located inside the first liquid nitrogen chamber 31. The connection between the superconducting cable 20 and the external power grid is achieved through the current lead 70. Therefore, the section of the current lead 70 in the first liquid nitrogen chamber 31 is in a low-temperature environment, while the section of the current lead 70 outside the terminal cryogenic container 10 is in a normal-temperature environment. That is, the temperature distribution of the current lead 70 is: gradually increasing in temperature along the direction away from the superconducting cable 20.

[0038] In particular, such as Figure 5 and Figure 6 As shown, the current lead 70 includes a lead body section 71 and a lead superconducting composite section 72. At least a portion of the lead superconducting composite section 72 is located in the first liquid nitrogen chamber 31. The lead superconducting composite section 72, from the inside out, includes a conductor inner core 721, a superconducting layer 722, and a conductor outer jacket 723. The two ends of the conductor inner core 721 are fixedly connected to the lead body section 71 and the cable core 21, respectively. The connection method can be welding, crimping, or adapter connection. In this way, by embedding the superconducting layer 722 into the metallic current lead 70, in the temperature range below the critical temperature of the superconducting layer 722, the superconducting layer 722 carries all or part of the current in a non-resistance manner, thereby effectively reducing the Joule heat loss of the current lead 70 and achieving energy-saving effect.

[0039] Preferably, the superconducting layer 722 is made of Bscco superconductor, which allows the superconducting layer 722 to function in a more unobstructed manner for an extended period.

[0040] Furthermore, such as Figure 6 As shown, the lead body segment 71 and the conductor core 721 are an integral structure. Both the lead body segment 71 and the conductor core 721 are made of copper, aluminum, or an alloy. The outer diameter of the lead body segment 71 is larger than the outer diameter of the conductor core 721, creating a step at the junction of the current lead 70 and the lead body segment 71 and the conductor core 721. The superconducting layer 722 is an annular sleeve, fixedly covering the outer circumference of the conductor core 721, and can be fixed by welding or threaded connection. The conductor outer sleeve 723 is an annular sleeve, fixedly covering the outer circumference of the superconducting layer 722, and can also be fixed by welding or threaded connection. Furthermore, under DC conditions, the conductor outer sleeve 723 can be made of a ferromagnetic material.

[0041] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0042] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A superconducting cable termination conductor connection structure, comprising a terminal cryogenic container (10) and a superconducting cable (20), wherein the terminal cryogenic container (10) comprises a container body (30), a first liquid nitrogen chamber (31) formed within the container body (30), a cable interface (32) opened on the container body (30) and communicating with the first liquid nitrogen chamber (31), and a container flange (33) fixed at the cable interface (32), wherein the superconducting cable (20) comprises a cable core (21) and a cable sleeved on the cable core (21). The cable insulation pipe (22) on the outer periphery, the second liquid nitrogen chamber (23) formed between the cable core (21) and the cable insulation pipe (22), and the cable flange (24) fixed at the end of the cable insulation pipe (22), one end of the cable core (21) extends into the first liquid nitrogen chamber (31) from the cable interface (32), the first liquid nitrogen chamber (31) and the second liquid nitrogen chamber (23) are connected through the cable interface (32), and the container flange (33) and the cable flange (24) are fixedly connected, characterized in that: It also includes a first sealing ring (40) disposed at the junction of the container flange (33) and the cable flange (24). The first sealing ring (40) includes a hollow support frame (41), a metal sealing layer (42) fixedly covering the outer periphery of the support frame (41), and a filling layer (43) filled in the support frame (41). The hardness of the support frame (41) is greater than the hardness of the metal sealing layer (42) and the hardness of the filling layer (43). The support frame (41) has an opening (411). The radial thickness of the support frame (41) gradually decreases from the middle to both ends along its circumference, so that the support frame (41) has a thin part (412) at the opening (411). The opening (411) of the first sealing ring (40) faces the first liquid nitrogen chamber (31).

2. The superconducting cable terminal conductor connection structure according to claim 1, characterized in that: The material of the supporting frame (41) is stainless steel or copper, and the material of the metal sealing layer (42) is tin, lead, indium, or soft alloy.

3. The superconducting cable terminal conductor connection structure according to claim 1 or 2, characterized in that: The metal sealing layer (42) and the filling layer (43) are made of the same material.

4. The superconducting cable terminal conductor connection structure according to claim 1, characterized in that: The cable insulation pipe (22) is a single-layer pipe.

5. The superconducting cable terminal conductor connection structure according to claim 1, characterized in that: The cable insulation pipe (22) is a double-layer pipe, which includes an inner pipe body, an outer pipe body, and a vacuum cavity formed between the inner pipe body and the outer pipe body. The cable core (21) is installed inside the inner pipe body of the cable insulation pipe (22).

6. The superconducting cable terminal conductor connection structure according to claim 1, characterized in that: The terminal cryogenic container (10) further includes a port (34) opened on one side of the first liquid nitrogen chamber (31), a port flange (35) fixed at the port (34), and an end plate (50). The end plate (50) is fixedly connected to the port flange (35) and the end plate (50) blocks the port (34). A second sealing ring (60) is provided at the junction of the end plate (50) and the port flange (35). The structure of the second sealing ring (60) is the same as that of the first sealing ring (40). The opening (411) of the second sealing ring (60) faces the first liquid nitrogen chamber (31).

7. The superconducting cable terminal conductor connection structure according to claim 1, characterized in that: It also includes a current lead (70), one end of which extends into the first liquid nitrogen chamber (31) and is connected to the cable core (21) located in the first liquid nitrogen chamber (31).

8. The superconducting cable terminal conductor connection structure according to claim 7, characterized in that: The current lead (70) includes a lead body section (71) and a lead superconducting composite section (72). At least a portion of the lead superconducting composite section (72) is located in the first liquid nitrogen chamber (31). The lead superconducting composite section (72) includes, from the inside out, a conductor core (721), a superconducting layer (722), and a conductor jacket (723). The two ends of the conductor core (721) are fixedly connected to the lead body section (71) and the cable core (21), respectively.

9. The superconducting cable terminal conductor connection structure according to claim 8, characterized in that: The superconducting layer (722) is made of Bscco superconductor.

10. The superconducting cable terminal conductor connection structure according to claim 8, characterized in that: The lead body segment (71) and the conductor core (721) are an integral structure, and the materials of the lead body segment (71) and the conductor core (721) are copper, aluminum, or alloy.

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