HK1111809B - Cryogenic apparatus of superconducting equipment - Google Patents

Description

Cryogenic device for superconducting apparatus

Technical Field

The present invention relates to a cryogenic device for a superconducting apparatus that houses a bushing for communicating electric power between a cryogenic side and a room temperature side, and also relates to a terminal structure of a superconducting cable including the cryogenic device. In particular, the present invention relates to a cryogenic device of a superconducting apparatus having excellent assembling workability.

Background

Fig. 5 shows an example of a terminal structure of a known superconducting cable (see patent document 1). The terminal structure is connected to a cable core 100 leading out from a terminal of the superconducting cable so as to communicate electric power between a cryogenic side and a room temperature side. Specifically, the terminal structure includes: the superconductor 100a exposed from the core 100; a bushing 101 for providing electrical connection between the superconductor 100a and a conductor (not shown) disposed at the room temperature side; a coolant container 102 accommodating a terminal end of the bushing 101 on the low temperature side and a connection portion 110, the connection portion 110 connecting the superconductor 100a and the bushing; a porcelain tube 104 protruding from the room temperature side of the vacuum vessel 103.

The bushing 101 includes a central conductive portion 101a electrically connected to the superconductor 100a through a connection portion 110 and a solid insulating layer 101b covering the conductive portion 101a and formed of FRP. The bushing 101 is accommodated in the coolant container 102 and the porcelain tube 104. In this example, the superconductor 100a is connected to a connection conductor 120 formed of a normal conductor material such as copper. The connection conductor 120 is connected to the conductive portion 101a of the bushing 101 through the connection portion 110. The sleeve 101 has flanges 101c and 101d around its periphery. The sleeve 101 is fixed to the coolant container 102 by a flange 101c and to the vacuum container 103 by a flange 101 d.

The coolant container 102 is filled with a liquid coolant such as liquid nitrogen to cool the sleeve 101, the connection portion 110, and the connection conductor 120. The vacuum vessel 103 includes a cylindrical intermediate vacuum portion 103a connecting the coolant vessel 102 on the low temperature side and the porcelain tube 104 on the room temperature side. The sleeve 101 is inserted into the intermediate vacuum portion 103a to reduce heat penetration from the room temperature side to the low temperature side. That is, a portion of the vacuum vessel 103 has a double structure including an intermediate vacuum part 103a and an outer vacuum part 103 b. The porcelain tube 104 is filled with an insulating fluid such as insulating oil or SF6 gas.

Patent document 1: japanese unexamined patent application publication No.2002-

Disclosure of Invention

Technical problem to be solved by the invention

However, the above-described known terminal structure is time-consuming to assemble and requires improved workability. In particular, there is a need to reduce the amount of work at the installation site.

The terminal structure is conventionally assembled by the following process: connecting the superconductor and the sleeve; assembling a coolant container; assembling a vacuum container; fixing the sleeve on the coolant container and the vacuum container; and a vacuum-pumping container. With the known terminal structure described above, the vacuum vessel cannot be evacuated before the sleeve is fixed to the coolant vessel and the vacuum vessel because some components of the sleeve (the flanges 101c and 101d in the example of fig. 5) constitute a part of the coolant vessel and the vacuum vessel. Further, the vacuum vessel requires excellent thermal insulation, that is, a high vacuum is required because a coolant such as liquid nitrogen used in a superconducting apparatus including a superconducting cable has an extremely low temperature (77K for liquid nitrogen). Further, a thermal insulator such as Super Insulation (registered trademark) is generally disposed in the vacuum vessel to improve Insulation. When the terminal structure is assembled at the installation site, the thermal insulator may absorb, for example, moisture by exposure to air prior to evacuation. Therefore, it takes much time to evacuate the vacuum vessel to a high vacuum.

The baking can effectively reduce the vacuumizing time. In baking, an article is heated to evaporate moisture, for example, contained therein. However, the above-described terminal structure is relatively large and requires a correspondingly large baking apparatus (including a heater and a power supply). Such baking apparatus are difficult to transport to the assembly site. Furthermore, since the superconducting cable and the bushing are connected before baking, heating at a greatly increased baking temperature may damage the components of the termination structure, in particular the electrical insulation of the superconducting cable. To prevent damage to components such as the electrically insulating layer, baking must be performed at a relatively low temperature (e.g., about 70 ℃). Such baking does not alleviate the time consuming vacuum pumping problem.

Furthermore, in the event of an accident such as a vacuum leak, evacuation at the assembly site requires a backup assembly. This increases the number of components that are delivered to the assembly site.

After the sleeve is connected to the coolant container and the vacuum container, evacuation is performed not only in a terminal structure where the superconducting cable is assembled but also in a superconducting apparatus including a superconducting transformer, a superconducting Fault Current Limiter (FCL), and a superconducting energy storage apparatus, which is assembled for mounting the superconducting cable line. Such a device also requires improved assembly workability.

Accordingly, it is a primary object of the present invention to provide a cryogenic device of a superconducting apparatus having excellent assembling workability and a terminal structure of a superconducting cable including the cryogenic device. It is another object of the present invention to provide a cryogenic device for superconducting equipment that can be easily transported to the assembly site.

Technical scheme for solving technical problem

According to the present invention, the above object is achieved by providing a vacuum element which maintains a vacuum with or without a sleeve. That is, the present invention provides a cryogenic device for a superconducting apparatus for accommodating a connection portion connecting a terminal of a superconducting portion provided on a cryogenic side and a sleeve connected to the superconducting portion for communicating electric power between the cryogenic side and a room temperature side. The low-temperature apparatus includes a coolant container that accommodates a terminal end and a connection portion of a bushing on a low-temperature side and is filled with a coolant for cooling the terminal end and the connection portion, and a vacuum container that is provided to surround the coolant container. The cryogenic device of the present invention is primarily characterized in that the vacuum vessel comprises a first vacuum section capable of maintaining a vacuum regardless of the presence of the sleeve.

The vacuum portion of the cryogenic device of the present invention can be evacuated regardless of the presence of the sleeve, since the components of the sleeve do not form part of the coolant vessel or vacuum vessel. Thus, at least the vacuum portion can be pre-evacuated in, for example, a factory so as to reduce the workload, particularly the evacuation time, of the assembly site. In particular, the workload of the assembly site can be further reduced by maximizing the volume of the vacuum part, thereby further improving the assembly workability. Since the superconducting cable uses a relatively large cryogenic device, the effect of improved assembling workability is important for the superconducting cable.

As described above, the assembling operation at the installation site, particularly the evacuation, is time-consuming for the known terminal structure of the superconducting cable in which the tube assembly constitutes a part of the coolant container and the vacuum container. Although the time for evacuation can be reduced to some extent by baking, considerable effort must be expended in transporting the baking apparatus. The coolant container and the vacuum container may be assembled in a factory in advance before the assembly is delivered to an installation site, instead of assembling them at the installation site. However, known terminal structures are evacuated with the sleeve secured to the coolant container and the vacuum container. Since the terminal end of the bushing on the room temperature side protrudes, the transportation of the terminal structure may be difficult due to height restrictions. In particular, the known termination structure becomes more bulky after the porcelain tube is arranged around the protruding termination. In contrast, the vacuum portion of the cryogenic device of the present invention can be evacuated without securing the sleeve to the coolant vessel or vacuum vessel. The vacuum part can thus be evacuated beforehand in the factory and there is no need to fix the sleeve on the coolant container and the vacuum container during transport. Thus, the cryogenic device of the present invention can alleviate height restrictions in transportation. Furthermore, the vacuum portion can also be evacuated without the need for a sleeve, a connecting portion or a reinforcing insulating layer, for example in the coolant container. This allows baking to be carried out at high temperatures, which helps to reduce the evacuation time. The present invention will be described in detail.

The cryogenic device of the present invention can be applied to various superconducting apparatuses having a superconducting portion formed of a superconducting material. Examples of such superconducting devices include superconducting cables, superconducting transformers, superconducting fault current limiters, and superconducting energy storage devices. One example of the superconducting cable has a superconducting portion including a first superconducting layer and a second superconducting layer coaxially disposed around the first superconducting layer. For a superconducting transformer, a superconducting fault current limiter, or a superconducting energy storage device, for example, it includes a superconducting current limiting element formed of a superconducting material or a superconducting coil as a superconducting portion.

Another example of the superconducting cable includes a cable core having a superconducting portion and a thermal insulation pipe accommodating the core. An example of the cable core includes, in order from the center thereof outward, a former, a first superconducting layer, an electrically insulating layer, a second superconducting layer, and a shield layer. The second superconducting layer is disposed around the electrically insulating layer to function as, for example, a superconducting shield layer or a return conductor. The superconducting cable may be a single core cable including a single core or a multi-core cable including a plurality of cores. Further, the superconducting cable may be a cable for direct current transmission or a cable for alternating current transmission. Of course, known superconducting cables may be used.

The sleeve is connected to the terminal end of the superconducting portion through a connection portion. The bushing is an element for communicating electric power between the superconducting portion on the low temperature side and the conductor on the room temperature side. The sleeve is used for inputting or outputting electric power, or both. Specifically, the sleeve includes a conductive portion capable of being electrically connected to a superconducting portion of the superconducting device and a solid insulating layer disposed around the conductive portion. The conductive portion of the bushing is preferably formed of a conductive material: the conductive material exhibits low resistance in the vicinity of the use temperature (coolant temperature) of the superconducting device (for example, in the vicinity of the temperature of liquid nitrogen if liquid nitrogen is used as the coolant). The conductive material used is, for example, copper or aluminum (2X 10 at 77K)^-7Specific resistance ρ) of Ω · cm. The solid insulating layer may be composed of a resin material having excellent electrical insulating properties (for example, an insulating rubber material such as ethylene-propylene rubber). In particular, Fiber Reinforced Plastic (FRP) is a preferred material because of its high electrical insulation properties. One terminal end (terminal end on the low temperature side) of the bushing is housed in a low temperature device described later, and the other terminal end (terminal end on the room temperature side) of the bushing is housed in a porcelain tube protruding from the low temperature device or is disposed outside the room temperature. The porcelain tube is filled with an insulating fluid such as an insulating liquid or an insulating gas having high electrical insulation, for example, insulating oil or SF6 gas. A flange is disposed about the middle portion of the sleeve to secure the sleeve to the cryogenic device. Convex for useThe rim is a flange that can be fixed to the cryogenic device while maintaining a vacuum in a first vacuum section described later. The sleeve and the terminal end of the superconducting portion may be electrically connected through a connection portion. The connecting portion preferably has a shielding structure. The bushing can also be connected by a connection portion to a connection conductor which is connected to the superconducting portion and is formed of a plain conductor material such as copper.

The cryogenic device houses the terminal end and the connection portion of the bushing on the cryogenic side. The cryogenic device includes a coolant container filled with a coolant for cooling the terminal and the connection portion, and a vacuum container disposed to surround the coolant container. The coolant container includes, for example, a main body accommodating a terminal end and a connection portion of the sleeve on the low temperature side and a tubular portion accommodating the sleeve. The body is dimensioned such that it can accommodate the above-mentioned parts. The tubular portion has a size into which the cannula can be inserted. Although the tubular portion may be composed of flat tubes, it is preferable that a part of the tubular portion is composed of a deformable bellows tube because the bellows tube can absorb thermal contraction of the coolant container when the coolant container is cooled by the coolant. The coolant filling the coolant container is a liquid coolant or a coolant gas, or a liquid coolant and a coolant gas. The coolant gas used is, for example, nitrogen or helium. The liquid coolant used is, for example, liquid nitrogen or liquid helium. If the coolant container is filled with liquid coolant and coolant gas, these coolants may be of the same type or of different types. Further, if the coolant container is filled with the liquid coolant and the coolant gas, the coolant container preferably has a liquid coolant area filled with the liquid coolant on the low temperature side and a coolant gas area filled with the coolant gas on the room temperature side. The coolant container and a vacuum container described later are preferably formed of a high-strength metal such as stainless steel.

The cryogenic device of the present invention is configured such that a sleeve can be inserted while a space surrounded by the outer surface of the coolant container and the inner surface of the vacuum container maintains vacuum after vacuum is drawn. Specifically, the cryogenic device of the present invention has a first vacuum portion inside the vacuum vessel into which the sleeve can be inserted while maintaining a vacuum in the first vacuum portion. Since the cryogenic device of the invention comprises the first vacuum part, the coolant container and the vacuum container which may be assembled in advance, for example in a factory, before the sleeve and the superconducting part are connected at the installation site. In order to connect the sleeve and the superconducting portion in the coolant container, it is preferable that the coolant container and the vacuum container have hand hole portions which can be opened while maintaining the vacuum of the first vacuum portion. Specifically, the coolant container, particularly, the body accommodating the connection portion includes a hand hole portion that can be opened and closed, and the vacuum container includes a hand hole portion that is provided at a position corresponding to the hand hole portion of the coolant container and can be opened and closed. The space in the vacuum vessel is preferably divided so that the vacuum can be maintained in the first vacuum portion regardless of whether the hand hole portion is opened or closed. For example, a cylindrical partition wall is provided to couple the coolant container and the vacuum container. The partition wall is fixed to the coolant container and the vacuum container such that one opening (on the vacuum container side) of the partition wall is positioned outside the opening of the hand hole portion of the vacuum container and the other opening (on the coolant container side) of the partition wall is positioned outside the opening of the hand hole portion of the coolant container. This structure prevents the vacuum in the first vacuum section from being broken when the opening of the hand hole section is opened. Preferably, a space surrounded by the inner surface of the partition wall, the outer surface of the hand hole portion of the vacuum container, and the inner surface of the hand hole portion of the coolant container is defined as the second vacuum portion. Even if the second vacuum portion is evacuated before, for example, the connecting operation of the coolant container, the vacuum in the second vacuum portion is broken when the hand hole portion of the vacuum container is opened; however, the high vacuum formed in the first vacuum section by evacuation in advance in, for example, a factory can be maintained almost completely, and only the second vacuum section needs to be evacuated. Further, at the installation site, the superconducting portion and the sleeve can be easily connected through the hand hole portion. Thus, the hand hole portion can eliminate the need to fix the sleeve to the coolant container and the vacuum container in the transportation of the cryogenic device of the present invention, thereby alleviating the height restriction.

The hand hole portion includes an opening provided in the coolant container and a lid portion that can be opened and closed and that can seal the opening hermetically. The hand hole portion includes an opening provided at a position of the vacuum container corresponding to the hand hole portion of the coolant container and a cover portion that can be opened and closed and can hermetically seal the opening. The cylindrical partition wall is fixed to the coolant container and the vacuum container such that one opening of the partition wall is positioned outside the opening of the coolant container and the other opening of the partition wall is positioned outside the opening of the vacuum container. If the partition wall is connected to the coolant container, the coolant cools the partition wall and thus causes thermal contraction when filled into the coolant container. The partition wall preferably has a mechanism capable of absorbing heat shrinkage to prevent the coolant container and the vacuum container from being broken due to the heat shrinkage. For example, at least part of the partition wall may be comprised of a deformable member such as a bellows.

The vacuum vessel is disposed to surround the coolant vessel. As described above, the space in the vacuum vessel is not necessarily a single communicating space, but may be divided into separate several spaces to form a plurality of vacuum portions. Specifically, in the case where the assembly of the low temperature device does not include the assembly of the sleeve, the second vacuum part may be formed to surround the hand hole part in addition to the first vacuum part. With this structure, for example, the operations of connecting the sleeve and mounting the connecting portion can be performed after assembling and evacuating the coolant container and the vacuum container, thereby reducing the time for evacuating at the installation site.

The vacuum vessel may be simply evacuated to a predetermined degree of vacuum, or a thermal Insulation layer for reflecting radiant heat in evacuation may be formed using a thermal insulator such as Super Insulation (trademark). The evacuation in the second vacuum section and the formation of thermal insulation are preferably performed after the connection section is mounted in the coolant container and the opening of the hand hole section of the coolant container is closed with the lid section.

Furthermore, if the vacuum vessel has a support structure capable of supporting the coolant vessel on the vacuum vessel, the support structure can prevent damage caused by vibration in, for example, transportation or installation. If the support structure used is, for example, a support assembly that is fixed to couple the vacuum vessel and the coolant vessel, the support assembly may transfer heat to the coolant vessel. If the support member is fixed to the vacuum container and the coolant container, the support member is preferably formed of a material with low thermal conductivity (for example, a resin such as FRP). Alternatively, a support structure that can couple the vacuum container and the coolant container in transportation or installation and can be separated from the coolant container in use of the superconducting device is more preferably used to prevent heat from being transferred to the coolant container side through the support structure. Such a support structure includes, for example, a shaft portion which can move forward and backward through a wall portion of the vacuum container and a contact portion which is connected to the shaft portion and can come into contact with or separate from the coolant container when the shaft portion moves forward and backward. In this case, the vacuum vessel preferably includes a third vacuum section isolated into a space different from the first and second vacuum sections so that the vacuum in the first and second vacuum sections is not broken when the shaft section moves. In the third vacuum section, the shaft portion may move the contact portion into contact with or away from the coolant container while maintaining the vacuum in the first and second vacuum sections. Therefore, the third vacuum portion can prevent heat from being transferred to the coolant container side through the support structure. The third vacuum part may be a space surrounded by the coolant container, the vacuum container, and a partition wall coupling the coolant container and the vacuum container, or may be a space inside a deformable container closed at the bottom fixed to the vacuum container. In the latter case, it is possible to insert the shaft portion into the container of the third vacuum portion through the wall portion of the vacuum container and fix the shaft portion to the bottom portion of the container serving as the contact portion. Alternatively, the shaft portion may be inserted through the bottom portion instead of being fixed to the bottom portion such that the tip of the shaft portion protrudes from the bottom portion. In this case, the penetrating portion of the shaft portion is sealingly fixed to the bottom portion, and the contact portion is added to the tip of the shaft protruding from the bottom portion. The deformable container is preferably deformed when the shaft portion is moved. The movable contact portion of the support structure may keep the different coolant containers in contact during use of the superconducting device, as described above, or may be in contact with the coolant containers during use in case of, for example, an earthquake to more stably support the coolant containers. In this case, if at least one surface of the contact portion that is in contact with the coolant container is formed of a material with low thermal conductivity such as FRP, the amount of heat transmitted to the coolant container side through the support structure can be reduced. More preferably, both the contact portion and the shaft portion are formed of a material having low thermal conductivity. The third vacuum part may be vacuumed to a degree of vacuum similar to or lower than that of the first vacuum part. Furthermore, the shaft portion is preferably sealingly connected to the vacuum vessel so that the vacuum in the third vacuum portion is not broken when the shaft portion is moved but is still maintained.

The cryogenic device of the present invention having the above-described structure is particularly suitable for use as a terminal connection box for a superconducting cable. That is, the terminal structure of the superconducting cable of the present invention includes a terminal of the superconducting cable disposed on the cryogenic side, a bushing for communicating electric power between the cryogenic side and the room temperature side, a connection portion connecting the terminal of the superconducting cable and the bushing, and a terminal connection box accommodating the connection portion. The above-described cryogenic device having the first vacuum portion is used as a terminal connection box.

Advantages of the invention

The vacuum vessel of the cryogenic device of the present invention includes a vacuum portion that maintains a vacuum regardless of the presence of the sleeve. Thus, the vacuum vessel may be evacuated to a high vacuum in advance, for example, in a factory. This contributes to improved workability at the installation site. Further, during transportation, the vacuum in the first vacuum portion can be maintained without fixing the sleeve to the coolant container or the vacuum container. Thus, the cryogenic device of the present invention can be shipped without a sleeve attached thereto. This alleviates transportation problems such as height restrictions. In particular, if the coolant container and the vacuum container have hand hole portions and the second vacuum portion is isolated from the first vacuum portion, the sleeve and the superconducting portion can be easily connected by the second vacuum portion at the installation site while maintaining the vacuum in the first vacuum portion.

Drawings

Fig. 1 is a partially cut-away schematic view of the entire terminal structure of a superconducting cable of the present invention.

Fig. 2 is a schematic view of a partial cross section of a cable core and its vicinity in a terminal structure of a superconducting cable of the present invention.

Fig. 3 is an enlarged cross-sectional view of a bushing portion in a terminal structure of a superconducting cable of the present invention.

Fig. 4(a) is a partial cross-sectional view showing a hand hole portion and its vicinity in a terminal structure of a superconducting cable of the present invention; FIG. 4(B) is a schematic partial cross-sectional view of a support structure having a mechanism capable of moving into and out of contact with a coolant container; and FIG. 4(C) is a partial cross-sectional schematic view of a support structure having a contact portion on a coolant container.

Fig. 5 is a schematic view of a known termination structure of a superconducting cable.

Reference numerals

1 superconducting cable

2 connecting part

3 terminal connection box (Low temperature device)

10 casing

11 conductive part

12 solid insulating layer

13 Flange

14 upper shield

20 Coolant container

21 main body

22 tubular portion

23 Flange

24 hand hole portion of coolant container

25 opening

26 cover part

30 vacuum container

30a fixed part

Assembly of 30d, 30m and 30u vacuum vessels

31 first vacuum part

32 second vacuum section

33 third vacuum part

34 hand hole part of vacuum container

35 opening

36 cover part

38 partition wall

38a corrugated tube

38b flat tube

40 porcelain tube

50 cable core

51 superconductor

52 connecting conductor

52a connecting sleeve

53 reinforced insulating layer

54 epoxy resin unit

54a flange

55 connecting coolant container

56 connecting vacuum container

57 flange

60 and 67 support structure

61 contact part

62 shaft part

63 corrugated pipe

64 bottom part

65 contact part

66 thermal insulation layer

70 transport means

100 cable core

100a superconductor

101 casing

101a conductive part

101b solid insulating layer

101c and 101d flanges

102 coolant container

103 vacuum container

103a middle vacuum part

103b outer vacuum part

104 porcelain tube

110 connecting part

120 connecting conductor

Detailed Description

An embodiment of the present invention will now be described.

[ Structure ]

Fig. 1 to 3 schematically illustrate the terminal structure of the superconducting cable of the present invention. Fig. 1 is a partial cross-sectional view of the entire terminal structure. Fig. 2 is a partial cross-sectional view of a cable core and its vicinity. Fig. 3 is an enlarged sectional view of the sleeve portion. The terminal structure communicates electric power between the room temperature side and the low temperature side through the bushing 10. One end of the superconducting cable 1 is disposed on the cryogenic side. Specifically, the terminal structure includes a terminal of the superconducting cable 1, a bushing 10 connected to the superconductor 51 of the cable 1 for providing electrical connection between the cryogenic side and the room temperature side, a connection part 2 connecting the terminal of the cable 1 and the bushing 10, and a terminal connection box (cryogenic device) 3 accommodating the connection part 2. The terminal connection box 3 accommodates the terminal (terminal on the low temperature side) of the bushing 10 and the connection portion 2. The terminal connection box 3 includes a coolant container 20 filled with a coolant for cooling the terminal and connection portions 2 of the bushing 10 and a vacuum container 30 arranged to surround the coolant container 20. The porcelain tube 40 protrudes from the room-temperature side of the vacuum vessel 30 and receives the other terminal end (the terminal end of the room-temperature side) of the bushing 10. The terminal structure is mainly characterized in that the inner space of the vacuum vessel 103 is divided into different sections including a vacuum section (first vacuum section 31) capable of maintaining vacuum regardless of the presence or absence of the sleeve 10, a second vacuum section 32 described later, and a third vacuum section 33 described later. Each of which will be described in detail.

The superconducting cable 1 used in the present embodiment is a stranded three-core cable including three cable cores 50 and is housed in a thermal insulation pipe. Each core 50 includes, in order from the center to the outside, a shaped piece, a superconductor (first superconducting layer) 51, an electrically insulating layer, a second superconducting layer, and a shield layer. The heat insulating pipe has a double structure including an inner pipe filled with a coolant (liquid nitrogen in this embodiment) and an outer pipe disposed therearound. The space between the inner tube and the outer tube is evacuated to a predetermined vacuum degree. The superconductor 51 is exposed by the terminal end of the stripped core 50 and is connected to the copper connection conductor 52 by a connection sleeve 52 a. The connection conductor 52 is introduced into the coolant container 20. The reinforcing insulating layer 53 covers the exposed superconductor 51, the connection sleeve 52a and the connection conductor 52. An epoxy unit 54 is provided to surround a part of the connection conductor 52. The epoxy unit 54 has a flange 54a fixed to the coolant container 20 to hold the superconductor 51 in place. The terminal end of the core 50, a part of the auxiliary insulating layer 53, and a part of the epoxy resin unit 54 are accommodated in a joint coolant container 55 filled with a coolant (liquid nitrogen in the present embodiment). The connection vacuum container 56 is provided to surround the connection coolant container 55. The space between the connection coolant container 55 and the connection vacuum container 56 is filled with a thermal insulator and is evacuated to a predetermined degree of vacuum to form a thermal insulation layer. Although only one core is shown in fig. 2, as shown in fig. 1, the other two cores are similarly connected and housed in a connecting coolant container 55 and a connecting vacuum container 56, and the corresponding connecting portions 2 are housed in the coolant container 20.

Each of the bushings 10 used in the present embodiment includes a conductive portion 11 capable of being electrically connected to the superconductor 51 and a solid insulating layer 12 covering the conductive portion 11. The conducting portion 11 of the bushing 10 is connected to the superconductor 51 through the connecting portion 2 (and the connecting conductor 52 in the present embodiment). The conducting part 11 is formed of copper, which exhibits low resistance around the temperature of liquid nitrogen. The solid insulating layer 12 is formed of FRP (glass fiber reinforced plastic) having excellent electrical insulation. A flange 13 is provided on the periphery of the middle portion of the sleeve 10 to fix the sleeve 10 to the coolant container 20. One surface of the flange 13 is provided on the coolant container side and the other surface is provided on the porcelain tube 40 side, and the flange 13 is not provided in the vacuum container 30. In this structure, the flange 13 serves as a seal for sealing the room-temperature side of the coolant container 20 and also serves as a boundary between the low-temperature side coolant container 20 and the room-temperature side porcelain tube 40. The connection portion 2 connecting the superconductor 51 and the bushing 10 has a shield structure (not shown), and the room temperature side bushing 10 is terminated with a copper upper shield 14 (see fig. 3).

In the present embodiment, the coolant container 20 includes a main body 21 and a tubular portion 22 (both formed of stainless steel). The main body 21 accommodates the terminal of the low temperature side bushing 10, the connection portion 2, and a part of the connection conductor 52. The tubular portion 22 has the sleeve 10 inserted therein. The main body 21 is a container having a size capable of accommodating the terminal end of the low temperature-side bushing 10, the connection portion 2 and a part of the connection conductor 52 and filled with liquid nitrogen. The main body 21 is connected to a refrigerator (not shown) for cooling liquid nitrogen and a piping system (not shown) for supplying and discharging liquid nitrogen in the circulation cooling. The tubular portion 22 is cylindrical and has a size into which the sleeve 10 can be inserted. The low temperature side of each tubular portion 22 is composed of a flat tube, and a part of the room temperature side of the tubular portion 22 is composed of a corrugated tube. The tubular portion 22 is filled with liquid nitrogen on its low temperature side (flat tube) and with nitrogen on its room temperature side (a part of the flat tube, the bellows, and a part higher than the bellows tube). The dimensions of the tubular portion 22 are adapted such that the boundary between the liquid coolant and the coolant gas is located in the space in the flat tube without the use of, for example, a pressurizing device. If a part of the tubular portion 22 is composed of a bellows, it can absorb thermal contraction of the coolant container 20 by deforming when the coolant container 20 is filled with the coolant and thus cooled. Furthermore, in this embodiment, the bellows is easily deformed because the tube is filled with nitrogen gas. Further, a sufficient temperature gradient can be formed between the low temperature side and the room temperature side by filling the tubular portion 22 with the liquid coolant and the coolant gas. Another flange 23 is provided on the terminal end of the tubular portion 22 on the room temperature side to fix the flange 13 of the grommet 10. The flange 23 also serves as a fixing member for fixing the tubular portion 22 to a vacuum vessel 30 described later.

A flange 57 having a hole for inserting the epoxy unit 54 is provided at the position of the lead-in connection conductor 52 of the main body 21. That is, the epoxy unit 54 and the flange 57 function as a seal that seals the low temperature side of the coolant container 20. The flange 57 also acts as a seal to seal the vacuum vessel 30.

In this embodiment, the body 21 also includes a hand hole portion of the coolant container 24. Fig. 4(a) is a partially enlarged sectional view of a hand hole portion, and fig. 4(B) is a partially enlarged sectional view of a support structure. The hand hole portion 24 includes an opening 25 in the main body 21 of the coolant container 20 and a lid portion 26, and the lid portion 26 can be opened and closed and can seal the opening 25 hermetically. That is, after the flange 13 of the sleeve 10 (see fig. 3) is fixed to the flange 23 (see fig. 3) and the epoxy resin unit 54 and the flange 57 (see fig. 2) are fixed to the opening of the low temperature side coolant container 20, the coolant container 20 can be opened and closed by opening and closing the lid portion 26.

The vacuum vessel 30 has a hand hole portion 34 of the vacuum vessel at a position corresponding to the hand hole portion of the coolant vessel 24. The hand hole portion 34 includes an opening 35 in the vacuum vessel 30 and a lid portion 36, and the lid portion 36 is openable and closable to seal the opening 35. The hand hole portion 34 is configured such that the cover portion 36 can be opened while most of the vacuum container 30 (a first vacuum portion 31 described later) maintains vacuum. Specifically, a cylindrical partition wall 38 is provided to couple the hand hole portion 24 of the coolant container 20 and the hand hole portion 34 of the vacuum container 30. The partition wall 38 partitions an outer space of the partition wall 38 and an inner space of the partition wall 38. Specifically, the partition wall 38 is fixed on the outer surface of the coolant container 20 and the inner surface of the vacuum container 30 such that one opening (coolant container side) of the partition wall 38 is positioned outside (around the periphery) of the opening 25 of the coolant container 20 and the other opening (vacuum container side) of the partition wall 38 is positioned outside (around the periphery) of the opening 35 of the vacuum container 30. In this structure, the lid portions 26 and 36 can be opened and closed while maintaining the vacuum in the first vacuum portion 31. In this embodiment, the partition wall 38 includes a deformable bellows 38a and a flat tube 38b connected in series. One end of the bellows 38a is fixed to the inner surface of the vacuum vessel 30 and one end of the flat tube is fixed to the outer surface of the coolant vessel 20. When the coolant container 20 is cooled by the coolant, the bellows 38a can absorb thermal contraction of the coolant container 20 by deformation.

The vacuum vessel 30 is provided to surround the coolant vessel 20. The internal space of the vacuum vessel 30 is not a single connected space but divided into different spaces. Referring to fig. 2, in particular, the inner space in the vacuum vessel 30 is divided into a first vacuum part 31, a second vacuum part 32, and a third vacuum part 33.

The first vacuum part 31 is a space defined around the sleeve 10 and below the coolant container 20, and occupies most of the inner space of the vacuum container 30. Specifically, the first vacuum portion 31 is a space surrounded by the inner surface of the flange 23 of the coolant container 20, the outer surface of the tubular portion 22, the outer surface of the main body 21, the outer surface of the partition wall 38 (see fig. 4), and the inner surface of the vacuum container 30. That is, the components of the first vacuum part 31 do not include the components of the sleeve 10. This configuration maintains the vacuum in the first vacuum section 31 regardless of the presence of the sleeve 10.

Referring to fig. 4, the second vacuum portion 32 is a space defined near the hand hole portions 24 and 34, and the hand hole portions 24 and 34 are used in, for example, installation of the connection portion 2. The second vacuum section 32 allows the coolant container 20 to be opened and closed while maintaining the vacuum in the first vacuum section 31. Specifically, the second vacuum portion 32 is a space surrounded by the outer surface of the lid portion 26 of the coolant container 20, the inner surface of the partition wall 38, and the inner surface of the lid portion 36 of the vacuum container 30. Since the second vacuum part 32 has a space independent of the vacuum part 31, the vacuum of the first vacuum part 31 can be maintained regardless of the opening and closing of the cover parts 26 and 36.

The terminal structure according to the present embodiment includes a support structure 60 and a coolant container support structure 67 (described later), and the support structure 60 serves to suppress vibration of the coolant container 20 in the vacuum container 30 to prevent breakage of the coolant container 20, for example, in transportation. Referring to fig. 4(B), each of the support structures 60 has a contact portion 61 that can be brought into contact with the main body 21 of the coolant container 20 and a shaft portion 62 that can move the contact portion 61 into contact with or away from the coolant container 20. A screw thread formed in a part of the periphery of the shaft portion 62 is engaged with the vacuum vessel 3. The vacuum vessel 30 has a threaded hole in which a thread formed on the shaft portion 62 is engaged. When the screw thread becomes tight or loose, the shaft portion 62 moves forward or backward to move the contact portion 61 into or out of contact with the coolant container 20. Then, the movement of the contact portion 61 may break the vacuum in the first vacuum portion through the screw hole of the vacuum vessel 30. In this embodiment, the third vacuum portion 33 is defined as follows: a bellows 63 with a closed bottom is fixed to the inner surface of the vacuum vessel 30 at a position where the shaft portion 62 is inserted. The third vacuum part 33 is surrounded by the inner surface of the bellows 63, the inner surface of the bottom part 64, and the inner surface of the vacuum vessel 30. The third vacuum part 33 has a different space from the first vacuum part 31. The tip of the shaft portion 62 protrudes from the bottom portion 64 of the bellows 63, and the contact portion 61 is provided at the tip of the shaft portion 62. The threaded tip formed on the shaft portion 62 is engaged into the threaded hole of the vacuum vessel 30, and the intermediate portion of the shaft portion 62 is inserted into the bellows 63 through the vacuum vessel 30. The other end of the shaft portion 62 passes through a bottom portion 64 of the bellows 63, and the passing portion of the shaft portion 62 is sealingly fixed to the bottom portion 64. The contact portion 61 is provided at the tip of the shaft portion 62 protruding from the base portion 64. Thus, the contact portion 61 is provided in the first vacuum section 31. When the shaft portion 62 moves forward or backward, it deforms the bellows 63 and moves the contact portion 61 so that it is brought into contact with or separated from the coolant container 20. Therefore, the third vacuum section 33 allows the movement of the contact section 61 while maintaining the vacuum in the first vacuum section 31 and the second vacuum section 32. The third vacuum portion 33 is preferably evacuated so as to maintain a vacuum therein regardless of the movement of the contact portion 61. If a thermal insulator is provided around the coolant container 20, the contact portion 61 may break the thermal insulator when in contact with the coolant container 20. Referring to fig. 4(C), a thermal insulation layer 66 may be provided on a portion of the coolant container 20 other than the contact portion 65 provided to contact the contact portion 61. The support structure 60 and the contact portion 65 are preferably formed of a material having high strength and low thermal conductivity, such as FRP.

[ Assembly method ]

Next, an assembling method of a terminal structure in which the terminal connection box 3 is assembled in, for example, a factory will be explained. First, the coolant container 20 is assembled. Specifically, the components of the tubular portion 22 of the coolant container 20 are connected to the components of the main body 21. Then, the cap portion 26 is fixed to the opening 25 of the hand hole portion 24. Thus, the coolant container 20 is assembled to open the room-temperature side thereof of the insert sleeve 10, and to open the low-temperature side thereof of the insert connection conductor 52 and the epoxy resin unit. Fasteners such as bolts may optionally be used for attachment; this also applies to the subsequent processes.

After the coolant container 20 is assembled, a thermal insulator is provided around the coolant container 20, if necessary. Then, the vacuum vessel 30 is assembled so as to surround the coolant vessel 20. Specifically, the partition wall 38 is connected to the outside of the opening 25 of the hand hole portion 24 provided in the coolant container 20. An assembly 30d of the vacuum vessel 30 is connected so as to cover the bottom of the main body 21 of the coolant container 20, and another assembly 30m of the vacuum vessel 30 is connected so as to cover the top of the main body 21. The bellows is connected to the vacuum vessel 30 so as to surround a part of the circumference of the coolant vessel 20 on the superconducting cable side (right side in fig. 2). The flange 57 is fixed to the opening of the bellows to hermetically connect the low temperature side of the vacuum vessel 30 of the superconducting cable 1. The bellows connected to the vacuum vessel 30 can absorb thermal contraction of the coolant vessel 20 by deformation when the coolant vessel 20 is filled with the coolant, thereby preventing problems such as breakage of the coolant vessel 20. As shown in fig. 4(a), the assembly 30m of the vacuum vessel 30 is fixed to the partition wall 38 such that a part of the assembly 30m surrounds the partition wall 38 and the opening 35 of the assembly 30m is positioned in the opening of the partition wall 38. The cover portion 36 is fixed to the opening 35 to form a space serving as the second vacuum portion 32.

The assembly 30u is attached to the top of the assembly 30m (on the room temperature side) so as to cover the periphery of the tubular portion 22 of the coolant container 20. A fixing portion 30a for fixing the flange 23 of the coolant container 20 is connected to an end of the room temperature side member 30 u. The fixing portion 30a connected to the flange 23 seals the room temperature side of the vacuum vessel 30 to form a space serving as the first vacuum portion 31. A seal is preferably provided between the fixed portion and the flange 23 to hermetically seal the first vacuum portion 31.

If the support structure 60 is provided, the shaft portion 62 is inserted and sealingly fixed to a bottom portion 64 of a bellows 63 closed at the bottom by the bottom, and an opening of the bellows 63 is fixed to the assembly 30d, for example, by welding, thereby forming a space serving as the third vacuum portion 33. A threaded portion is formed at the position of the insertion shaft portion 62 of the assembly 30 d. In addition to the support structure 60, a coolant container support structure 67 may also be provided. As shown in fig. 2, the support structure 67 supporting the coolant container 20 by suspending the coolant container 20 from the vacuum container 30 is different from the support structure 60 in that the coolant container 20 and the vacuum container 30 are constantly coupled. Therefore, the support structure 67 is preferably formed of a low thermal conductivity material such as FRP.

After the vacuum vessel 30 is assembled, the first vacuum part 31, the second vacuum part 32, and the third vacuum part 33 of the vacuum vessel 30 are evacuated to a predetermined vacuum degree. Specifically, at least the first vacuum portion 31 is evacuated to a high vacuum. Since the coolant container 20 does not accommodate, for example, a superconducting cable this time, the evacuation time can be reduced by baking at a high temperature. The second vacuum portion 32, in which the vacuum is broken when the hand hole portions 24 and 35 are opened, can be evacuated to a relatively low vacuum. Also, if the first vacuum part 31 is evacuated to a high vacuum, the third vacuum part 33 can be evacuated to a considerably low vacuum because the first vacuum part 31 occupies most of the vacuum insulation layer in this structure. The terminal connection box 3 is transported, for example, to an installation site with at least the first vacuum portion 31 evacuated.

In transporting the terminal connection box 3 of the present embodiment, the support structures 60 and 67 can prevent problems such as breakage of the coolant container 20 due to vibration during transportation. Further, the terminal connection box 3 can eliminate the need to fix the bushing 10 to the coolant container 20 and the vacuum container 30 in transportation, because the vacuum can be maintained in the first vacuum portion 31 without fixing the bushing 10. This alleviates transportation restrictions such as height restrictions.

The bushing 10 is inserted into an opening of the coolant container 20 transported to, for example, the room-temperature side of the terminal connection box 3 of the installation site. Then, the flange 13 is attached to the sleeve 10 and fixed to the flange 23 of the coolant container 20. For example, a seal is preferably provided between the flanges 13 and 20 to hermetically seal the coolant container 20 and the porcelain tube 40. On the other hand, the superconductor 51 is exposed by stripping the terminal of the superconducting cable and is connected to the connection conductor 52 by a connection sleeve 52 a. Then, the epoxy resin unit 54 is disposed around the connection conductor 52 and fixed on the flange 57 by the connection conductor 52 inserted into the insertion hole of the flange 57. Then, the hand hole portions 34 and 24 are opened for performing operations such as connecting the connection conductor 52 to the bushing 10 and forming the reinforcing insulation layer 53. After these operations, the openings 25 and 35 are closed by the lid portion 26 of the coolant container's hand hole portion 24 and the lid portion 36 of the vacuum container's hand hole portion 34, respectively, and the second vacuum portion 32 is evacuated.

Unlike the known art, the coolant container 20 and the vacuum container 30 are not configured after the operation such as the connecting operation, but the terminal connection box 3 may be previously configured before the operation such as the connecting operation. Further, before only the second vacuum part 32 is vacuumed, an operation such as a connecting operation may be performed while maintaining the vacuum in the first vacuum part 31. This reduces the workload of the vacuum-pumping operation at the installation site.

The reinforcing insulating layer 53 may also be formed around the superconductor 51 and the connection sleeve 52 a. The connection coolant container 55 is fixed to the flange 57, and the connection vacuum container 56 is fixed to the vacuum container 30 so as to surround the connection coolant container 55 and be evacuated to a predetermined vacuum degree. The porcelain tube 40 is connected to the room temperature side of the bushing 10. The coolant container 20 is filled with liquid nitrogen and nitrogen gas. The connecting coolant container 55 is filled with liquid nitrogen. The porcelain tube 40 is filled with SF6 or insulating oil. Thus, the terminal structure of the superconducting cable is completed.

If the support structure 60 is provided, the contact portion 61 is preferably separated from the coolant container 20 by loosening the shaft portion 62 after the terminal connection box 3 is mounted to a predetermined position. Alternatively, the terminal connection box 3 may be mounted on, for example, a transport vehicle 70 shown in fig. 1 so that the box 3 can move along with the thermal contraction of the superconducting cable 1.

Although the cryogenic device of the present invention is used as a terminal connection box of a superconducting cable in the above-described embodiment, the cryogenic device may also be used as a container for housing a superconducting portion of a superconducting transformer, a superconducting fault current limiter, or a superconducting energy storage device.

Industrial applicability

The cryogenic device of the present invention is suitable for housing a connection assembly for connecting the cryogenic side and the room temperature side of a superconducting apparatus. In particular, the cryogenic device of the present invention is suitable for use as a terminal connection box for a superconducting cable. Further, the terminal structure of the superconducting cable of the present invention is suitable for use as a terminal portion of the superconducting cable. The terminal structure can be used for direct current transmission and alternating current transmission.

Claims (8)

1. A cryogenic device of a superconducting apparatus for accommodating a terminal connecting a superconducting portion provided on a cryogenic side and a connection portion connected to a sleeve of the superconducting portion for communicating electric power between the cryogenic side and a room temperature side, the cryogenic device comprising:

a coolant container which accommodates the low temperature side sleeve terminal and the connection portion and is filled with a coolant for cooling the terminal and the connection portion; and

a vacuum container provided to surround the coolant container;

wherein the vacuum vessel includes a first vacuum portion capable of maintaining a vacuum regardless of the presence of the sleeve.

2. Cryogenic device of a superconducting apparatus according to claim 1, wherein

The coolant container includes a hand hole portion that can be opened and closed;

the vacuum container includes a hand hole portion which is provided at a position corresponding to the hand hole portion of the coolant container and can be opened and closed; and

the vacuum container further includes a second vacuum part surrounded by the two hand hole parts and a partition wall coupling the two hand hole parts.

3. The cryogenic device of a superconducting apparatus according to claim 2, wherein the partition wall has a contraction absorbing mechanism that absorbs thermal contraction of the coolant container due to the coolant.

4. Cryogenic device of a superconducting apparatus according to claim 1 or 2, wherein

The vacuum vessel having a support structure capable of supporting the coolant vessel;

the support structure includes a shaft portion extending from an outer side to an inner side of the vacuum container, and a contact portion connected to the shaft portion and movable into and out of contact with the coolant container when the shaft portion moves; and

the vacuum vessel includes a third vacuum portion capable of maintaining a vacuum regardless of the movement of the shaft portion.

5. The cryogenic device of a superconducting apparatus according to claim 1, wherein the superconducting apparatus is a superconducting cable, a superconducting transformer, a superconducting fault current limiter or a superconducting energy storage apparatus.

6. A terminal structure of a superconducting cable, comprising:

a terminal end of the superconducting cable disposed on the low temperature side;

a bushing for communicating electric power between the low temperature side and the room temperature side;

a connection portion connecting a terminal of the superconducting cable and the bushing; and

a terminal connection box accommodating the connection portion;

wherein the terminal connection block is a cryogenic device according to any one of claims 1-4.

7. The terminal structure of a superconducting cable according to claim 6, wherein the superconducting cable is a single core cable or a multi core cable.

8. The terminal structure of a superconducting cable according to claim 6 or 7, wherein the superconducting cable is a cable for direct current transmission or a cable for alternating current transmission.