Termination connection part for superconducting cable and cooling method of the superconducting cable

Abstract

To provide means of contributing to an improvement of a cooling efficiency of an entire superconducting system.SOLUTION: A communication part 41 that allows an inside of a flow path pipe 40 and an outside space 50 to communicate with each other is provided in the flow path pipe 40 housed in an inner housing portion 10. At the time of an initial cooling of a superconducting system, a coolant flows in the same direction from one terminal connecting part side to the flow path tube 40 and the outer space 50 provided in the other terminal connecting part, and a conductor is cooled while discarding a coolant that has reached the other terminal connecting part to the outside (a non-circulation step). Thereafter, in the other terminal connection part, a portion located on a downstream side of the communication part 41 provided in the flow path pipe 40 is entirely closed, and the coolant flowing only from the flow path pipe 40 is folded back to an outer space 50 by the communication part 41 to circulate the coolant in a superconducting cable (a circulation step). The flow of the coolant in the flow path pipe 40 and the flow of the coolant in the outer space 50 may be opposite to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a termination for a superconducting cable and a method for cooling the superconducting cable. [Background technology]

[0002] As a terminal connection part of a superconducting cable, a structure is known which has an inner housing tube part (211) that houses the cable core (11) of the superconducting cable (10) and an outer housing tube part (221) that surrounds this inner housing tube part (211) (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-9093 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional termination connections, in order to circulate the refrigerant flowing within the superconducting cable, it is necessary to provide an external return mechanism (not shown in Patent Document 1) to return the refrigerant flowing from one tube within the cable core to the other tube. However, the return mechanism attached externally to the termination connection part is in contact with the room temperature environment surrounding the termination connection part and is affected by heat penetration, which causes the temperature of the refrigerant passing through the return mechanism to rise, resulting in a problem of reduced cooling efficiency for the conductor. In addition, the length of the refrigerant flow path increases by the length of the external return mechanism, which can lead to increased pressure loss.

[0005] Therefore, one of the objects of the present invention is to provide a means for contributing to improving the cooling efficiency of the entire superconducting system. [Means for solving the problem]

[0006] The present invention, which has been made to solve the above-mentioned problems, is a termination connection part for connecting a superconducting cable, and comprises at least a flow path pipe connected to a first flow path of a refrigerant for cooling a conductor in the superconducting cable, and an inner accommodating part that accommodates the flow path pipe, wherein the inner accommodating part communicates an outer space, which is the space between the inner accommodating part and the flow path pipe, with a second flow path of a refrigerant for cooling the conductor in the superconducting cable, and the flow path pipe is provided with a communication part that communicates the inside of the flow path pipe with the outer space. The present invention also provides a method for cooling a superconducting cable using the above-mentioned terminal connection portion, characterized by including at least the steps of: (a) flowing a refrigerant in the same direction from one terminal connection portion to the flow path pipe and the outer space provided at the other terminal connection portion, and cooling the conductor while discarding the refrigerant that reaches the other terminal connection portion to the outside; and (b) after cooling the conductor, blocking all locations in the other terminal connection portion that are located downstream of the flow path of the refrigerant from the communicating portion, turning the refrigerant back at the communicating portion, and circulating the refrigerant between the first flow path and the second flow path within the superconducting cable. [Effects of the Invention]

[0007] According to the present invention, it is possible to minimize heat loss caused by the circulation of the coolant flowing through the termination joint for the superconducting cable, and as a result, it is possible to improve the cooling efficiency of the entire superconducting system. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the internal structure of a terminal connection part for a superconducting cable according to a first embodiment. [Figure 2] FIG. 4 is a schematic diagram showing the flow of refrigerant during initial cooling. [Figure 3] FIG. 4 is a schematic diagram showing the flow of refrigerant during circulating cooling. [Figure 4] FIG. 10 is a schematic diagram showing the operation of the telescopic tube. [Figure 5] 5A and 5B are schematic diagrams showing the operation of the drawing tube. [Figure 6]FIG. 10 is a schematic diagram showing the flow of a coolant during circulating cooling in a termination connection part according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0010] <1> Overview (Figure 1) FIG. 1 is a schematic diagram showing the internal structure of a terminal connection part for a superconducting cable according to the present invention. The terminal connection part A for a superconducting cable in this embodiment is a device for connecting a superconducting cable and also connecting it to a power source, which is the source of power, and various devices, which are the destinations of power, via power leads, to pass electricity between them.

[0011] <1.1> Superconducting cable A superconducting cable is a component that carries electricity by means of a conductor housed inside. In the present invention, the superconducting cable has at least a first flow path and a second flow path for flowing a coolant for cooling the conductor. In the present invention, it is assumed that the direction of the coolant flow in the first flow path and the second flow path is changed depending on the time of use.

[0012] <1.2> Aspects of each flow path In the present invention, the two tubes constituting the first flow path and the second flow path provided in the superconducting cable may have a structure in which one tube is housed within the other tube (multiple tube structure), or may have a structure in which they exist independently of each other within the superconducting cable (independent tube structure). In this embodiment, the inner tube in the superconducting cable serves as the first flow path, and the outer tube serves as the second flow path. The first flow path is connected to a flow path pipe 40 housed in the inner housing portion 10 described later, and the second flow path is connected to the space between the inner housing portion 10 and the flow path pipe 40 (outer space 50).

[0013] <1.3> Overall structure (Fig. 1) The terminal connection part A according to this embodiment is configured to include an inner accommodating part 10, an outer accommodating part 20, a telescopic tube 30, a flow path pipe 40, and the like. The components that make up the terminal connection part A will be described in detail below.

[0014] <2> Flow pipe (Figure 1) The flow path pipe 40 is a pipe that communicates with one of the coolant flow paths provided in the superconducting cable, and allows the coolant to flow within the terminal connection part A, and also allows the coolant to flow outside the flow path pipe 40 as necessary. In the present invention, the flow path tube 40 may be formed by drawing out the member that constitutes the first flow path within the superconducting cable as it is, or may be formed by a member separate from the member that constitutes the first flow path.

[0015] <2.1> Communication section (Fig. 1) The flow path pipe 40 according to the present invention is provided with a communication section 41 for communicating the inside and outside of the flow path pipe 40 . In the present invention, the number, shape, arrangement number, etc. of the communication portions 41 are not particularly limited. In this embodiment, the communication portion 41 is a through-hole formed by penetrating the peripheral wall of the tubular member that constitutes the flow path pipe 40 in the inside-outside direction of the pipe. The details of switching the refrigerant flow using the communication portion 41 will be described later. <6> This will be explained in the section.

[0016] <3> Inner storage compartment (Figure 1) The inner accommodating portion 10 is a member for accommodating the flow path pipe 40 . In the present invention, the shape of the inner accommodating portion 10 is not particularly limited. In this embodiment, the inner storage section 10 is configured by providing an inner partition wall 11, a tip tube 12, a drawer tube 13, and an inner lid 14.

[0017] <3.1> Internal partition (Fig. 1) The inner partition wall 11 is a member for connecting one end of the telescopic tube 30 . In the present invention, the shape of the inner partition wall 11 is not particularly limited. In this embodiment, the inner partition wall 11 is appropriately formed with a hole (insertion hole 111) for inserting the flow path pipe 40 and a hole (communication hole 112) for connecting the outer space 50 with the internal space of the tip tube 12.

[0018] <3.2> Tip tube (Fig. 1) The tip tube 12 is a member that becomes part of the flow path of the refrigerant in the terminal connection part A. In the present invention, the shape of the tip tube 12 is not particularly limited. In this embodiment, one end of the tip tube 12 is fixed to the inner partition wall 11, and the other end of the tip tube 12 is configured to have an inner lid 14 that can be attached and detached.

[0019] <3.3> Drawer tube (Fig. 1) The pull-out tube 13 forms part of the refrigerant flow path in the terminal connection part A, and is a component that is located inside the tip tube 12 during the assembly process of the terminal connection part A and is used to pull out the mounting location (seal mounting part 131) of the seal part 15, which is provided midway through the refrigerant flow path, to the outside of the outer accommodating part 20. In the present invention, the shape, structure, number of the draw-out tubes 13, etc. are not particularly limited. In this embodiment, the withdrawal tube 13 is made of a bellows (accordion tube), and one end of the withdrawal tube 13 is connected to the flow path pipe 40 extending from the inner storage section 10, and the other end is provided with a seal mounting section 131 described later.

[0020] <3.4> Inner lid (Fig. 1) The inner lid 14 is a member for separating the interior of the inner storage portion 10 from a vacuum space 60 formed by the outer lid 23, which will be described later. In this embodiment, the inner lid 14 is connected to the open end side of the tip tube 12 . The inner lid 14 is provided with a discharge hole 141a through which the refrigerant flowing through the flow path pipe 40 can be discharged, and a discharge hole 141b through which the refrigerant flowing through the outer space can be discharged.

[0021] <4> Outer housing (Fig. 1) The outer accommodating portion 20 is a member that constitutes the outer shell of the terminal connection portion A. In the present invention, the shape of the outer accommodating section 20 is not particularly limited. In this embodiment, the outer storage section 20 includes a heat insulating section 21, an outer wall 22, and an outer lid 23.

[0022] <4.1> Insulation section (Fig. 1) The heat insulating portion 21 is a member for suppressing heat penetration from the outside of the outer accommodating portion 20 into the inside of the inner accommodating portion 10 . In the present invention, the shape, material, arrangement, etc. of the heat insulating portion 21 are not particularly limited. In this embodiment, a heat insulating material is disposed inside the cylindrical main body of the outer accommodating section 20 to form a heat insulating section 21 .

[0023] <4.2> Exterior wall (Fig. 1) The outer wall 22 is a member that constitutes the end portion of the outer storage section 20. In the present invention, the shape of the outer wall 22 is not particularly limited. In this embodiment, an accommodation hole 221 is provided in the approximate center of the outer wall 22 arranged at the end of the outer accommodation section 20, and the tip tube 12 and the telescopic tube 30 can be accommodated inside through this accommodation hole 221. Furthermore, the end of the telescopic tube 30 is fixed to the inner wall side of the outer wall 22.

[0024] <4.3> Outer lid (Fig. 1) The outer lid 23 is a member for making the space closed by the outer lid 23 into a vacuum space 60 . In the present invention, the shape of the outer lid 23 is not particularly limited. In this embodiment, the outer lid 23 is fixed to the outer surface of the outer wall 22, and the internal space partitioned by the outer lid 23 is evacuated with a vacuum pump or the like to create a vacuum state. Furthermore, since the internal space of outer lid 23 is also connected to the space between tip tube 12 and telescopic tube 30, a vacuum space 60 is formed around the space through which the refrigerant flows, which is the internal space of tip tube 12. In other words, a vacuum space 60 is formed in the space between tip tube 12 and telescopic tube 30.

[0025] <5> Telescopic tube (Figure 1) The telescopic tube 30 is a member for absorbing stress that occurs in each component (for example, the outer accommodating section 20, etc.) connected to the inner accommodating section 10 due to thermal contraction of the inner accommodating section 10. In the present invention, the shape, structure, number of the telescopic tubes 30, etc. are not particularly limited. In this embodiment, a part of the telescopic tube 30 is made of a bellows (bellows tube), and the telescopic tube 30 connects between the inner partition wall 11 and the outer wall 22 .

[0026] <6> Cooling method (Fig. 2, Fig. 3) An example of the procedure for a method for cooling a superconducting cable in a superconducting system using a termination for a superconducting cable according to the present invention will be described below with reference to FIGS.

[0027] (1) Non-circulating process (Figure 2) When the conductor of the superconducting cable is not sufficiently cooled, such as when the superconducting system starts operating, a refrigerant is flowed in the same direction through the first and second flow paths in the superconducting cable from the opposite terminal connection side (not shown in Figure 2) to terminal connection part A (shown in Figure 2) to cool the conductor to a predetermined temperature. At this time, within the terminal connection portion A, although there may be a slight movement of the refrigerant between the flow path pipe 40 and the outer space 50 via the communication portion 41, the refrigerant being pressurized basically flows in the same direction within the terminal connection portion and is discharged to the outside through the discharge holes 141a and 141b and discarded.

[0028] (2) Circulation process (Fig. 3) After the conductor in the superconducting cable has been sufficiently cooled, the refrigerant discharge line is appropriately blocked at the terminal connection part shown in Figure 3, and the refrigerant supply line from the opposite terminal connection part side is switched to only the first flow path side (flow path pipe 40 side). In the present invention, the refrigerant discharge line may be blocked at any position downstream of the communication portion 41 . In FIG. 3, the vicinity of discharge hole 141a and discharge hole 141b is blocked. As a result, the refrigerant that has flowed through the flow path pipe 40 cannot be discharged from the discharge holes 141a, 141b, but is turned back into the outer space 50 via the communication section 41, and flows to the opposite terminal connection section through a second flow path in the superconducting cable that is connected to the outer space 50. On the opposite terminal connection side, the refrigerant that has been turned back is cooled again and pressure-fed to the first flow path again, thereby forming a refrigerant circulation line.

[0029] In addition, the present invention is not limited to the configuration in which the flow direction of the refrigerant is shown in Figure 3, and the refrigerant flowing from the outer space 50 may be turned back to the flow path pipe 40 via the communication part 41.

[0030] <7> Operational image (Fig. 4, Fig. 5) Next, the internal operation of the termination connection unit A according to this embodiment will be described with reference to FIGS.

[0031] <7.1> Operation of the telescopic tube (Fig. 4) When the superconducting system is in operation, the inner accommodating portion 10 is cooled by the refrigerant flowing through the flow path pipe 40 and the outer space 50 and undergoes thermal contraction, while the outer accommodating portion 20 is in contact with the outside of the terminal connection portion A, resulting in a difference in thermal contraction between the two. As a result, the internal partition wall 11 of the internal storage section 10 moves toward the right side of the paper in Figure 4 relative to the external wall 22 of the external storage section 20 due to stress generated by the difference in thermal contraction, acting in the direction of widening the gap between the external wall 22 and the internal partition wall 11. At this time, the telescopic tube 30 connecting the outer wall 22 and the inner partition wall 11 expands in response to the movement of the inner partition wall 11 (for example, the telescopic tube 30 becomes extended as shown in Figure 4), thereby suppressing the occurrence of tensile stress on the outer wall 22.

[0032] <7.2> Operation of the drawer (Fig. 5) In the process of assembling the terminal connection part A of the present invention, while the inner accommodating part 10 and the outer accommodating part 20 are appropriately assembled, a seal part 15 for sealing between the inside and outside of the draw-out tube 13 is attached to the end opposite to the end of the draw-out tube 13 that is connected to the flow path pipe 40. In order to improve the efficiency of this attachment work, it may be desirable to pull out the seal attachment portion 131 to the outside of the outer accommodating portion 20 . At this time, by pinching the seal mounting portion 131 and pulling it toward the left side of the paper in Figure 5, the pull-out tube 13 is extended and the seal mounting portion 131 is pulled out and exposed outside the outer storage portion 20, allowing the installation work of the seal portion 15 to be performed in an open space.

[0033] <8> summary According to the present invention, at least one of the following effects can be obtained. (1) There is no need to provide an external return mechanism for the terminal connection. (2) Since heat intrusion caused by the return mechanism is eliminated, the decrease in the cooling efficiency of the conductor can be suppressed. (3) By eliminating the return mechanism, the refrigerant flow path can be shortened, thereby reducing pressure loss. (4) The telescopic tube 30 absorbs changes in the distance between the outer accommodating section 20 and the inner accommodating section 10, thereby suppressing stress on the outer accommodating section 20 caused by thermal contraction of the inner accommodating section 10. This effect is not limited to the outer accommodating section 20, but also applies to other components directly or indirectly connected to the inner accommodating section 10. (5) The seal attachment portion 131 located midway along the refrigerant flow path can be drawn out of the outer accommodating portion 20 by extending the drawing tube 13, thereby improving the efficiency of the assembly work of the terminal connection portion A.

[0034] This makes it possible to provide a termination for superconducting cable with improved cooling efficiency compared to conventional models, and ultimately with stable performance that contributes to a decarbonized society. This will contribute to Goal 7 of the Sustainable Development Goals (SDGs), "Ensure access to affordable, reliable, sustainable and modern energy for all" and Goal 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation," which are international goals aimed at achieving a sustainable and better world by 2030 as set out in the 2030 Agenda for Sustainable Development adopted at the United Nations Summit in September 2015. [Example]

[0035] Second Embodiment The internal structure of a termination connector according to a second embodiment of the present invention will be described with reference to FIG.

[0036] <1> Modified example of the communication part (Fig. 6) In Example 1, the communicating portion 41 was formed by a through hole provided in the peripheral wall of the flow path pipe 40, whereas in this example, the connecting portion 41 is formed by leaving the end position of the flow path pipe 40 open inside the tip tube 12, while excluding the withdrawal tube 13 according to Example 1.

[0037] <2> Cooling method (Figure 6) In the configuration of this embodiment, in the non-circulation process described in the cooling method of embodiment 1, the refrigerant in the flow path pipe 40 and the refrigerant in the outer space 50, which flow in the same direction, are mixed inside the tip tube 12 and are discharged from the discharge hole 141c provided in the inner lid 14 (the flow of the refrigerant in the non-circulation process is not shown). Furthermore, in the circulation process described in the cooling method of the first embodiment, if the discharge hole 141c is appropriately blocked, the refrigerant that has flowed through the flow path pipe 40 will be turned back into the outer space 50 by the communication part 41 (see FIG. 6).

[0038] In addition, the present invention is not limited to the configuration in which the flow direction of the refrigerant is shown in Figure 6, and the refrigerant flowing from the outer space 50 may be turned back to the flow path pipe 40 via the communication part 41.

[0039] Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the specific embodiments described above. Various modifications and changes to the specific examples described in the above embodiments are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0040] A: Termination connection part 10: Inner storage section 11: Internal septum 111: Insertion hole 112:Communication hole 12:Tip tube 13: Pull-out tube 131: Seal mounting part 14: Inner lid 141a, 141b, 141c: Discharge hole 15: Seal part 20: Outer storage section 21: Insulation section 22: Exterior wall 221: Storage hole 23: Outer lid 30: Telescopic tube 40: Flow pipe 50:Outside space 60: Vacuum space

Claims

1. A terminal connection part for connecting a superconducting cable, a flow path pipe communicating with a first flow path of a coolant for cooling a conductor in the superconducting cable; an inner accommodating portion that accommodates the flow path pipe; The inner storage section is an outer space between the inner accommodating portion and the flow path pipe is connected to a second flow path of a coolant for cooling a conductor in the superconducting cable; The flow path pipe A communication part is provided to communicate the inside of the flow path pipe with the outside space. Termination joint for superconducting cable.

2. A method for cooling a superconducting cable using a termination connection part for connecting a superconducting cable having at least a flow path pipe communicating with a first flow path of a refrigerant for cooling a conductor in the superconducting cable and an inner accommodating part that accommodates the flow path pipe, wherein the inner accommodating part communicates an outer space between the inner accommodating part and the flow path pipe with a second flow path of a refrigerant for cooling the conductor in the superconducting cable, and the termination connection part is provided with a communication part that communicates the inside of the flow path pipe with the outer space, (a) a step of flowing a refrigerant from one terminal connection portion side to the flow path pipe and the outer space provided at the other terminal connection portion in the same direction, and cooling the conductor while discharging the refrigerant that has reached the other terminal connection portion to the outside; (b) after cooling the conductor, closing all of the locations at the other end connection portion that are located downstream of the communication portion in the flow path of the refrigerant, and turning the refrigerant back at the communication portion to circulate the refrigerant between the first flow path and the second flow path in the superconducting cable; Characterized in that it includes at least Cooling method for superconducting cables.

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