JP2009048794A - Superconducting cable line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting cable line capable of lessening the volume of outflow of a liquid refrigerant even though a cable is damaged. <P>SOLUTION: The superconducting cable line includes a core 10, and a heat insulation pipe 20 for covering its outside. The core 10 in this line includes a former 11 as a circulation passage of the refrigerant, a superconducting conductor layer 12 arranged outside the former 11, and an electric insulation layer 13 arranged outside the conductor layer 12. Then, a space 30 is formed between the core 10 and the heat insulation pipe 20, and a substance in the space is not circulated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a superconducting cable line. In particular, in a superconducting cable having a core and a heat insulating tube, the present invention relates to a superconducting cable line that can reduce the amount of refrigerant leakage even when the heat insulating tube is damaged due to an accident or the like.

  As a three-core collective superconducting cable, there is one shown in FIG. 4 (see, for example, Patent Document 1). The superconducting cable 100P has a configuration in which three cable cores 110 are twisted and housed in a heat insulating tube 120.

  The heat insulating tube 120 has a structure in which a heat insulating material (not shown) is disposed between the double tubes composed of the inner tube 121 and the outer tube 122, and the inside of the double tube is evacuated. Among these, the anticorrosion layer 123 is formed on the outer tube 122. Each cable core 110 includes a former 111, a superconducting conductor layer 112, an insulating layer 113, a shield layer 114, and a protective layer 115 in order from the center.

  Here, the former 111 is composed of, for example, a metal pipe, and the inside of the pipe is a flow path for a refrigerant such as liquid nitrogen. The superconducting conductor layer 112 is configured by spirally winding a superconducting wire on the former 111 in multiple layers. The insulating layer 113 is configured by winding semi-synthetic insulating paper. The shield layer 114 is formed by spirally winding a superconducting wire similar to the superconducting conductor layer 112 on the insulating layer 113. The shield layer 114 is induced with a current of approximately the same magnitude in the opposite direction as the current flowing in the superconducting conductor layer 112 during cable operation. With the magnetic field generated by the induced current, the magnetic field generated from the superconducting conductor layer 112 can be canceled and the leakage magnetic field to the outside of the cable core 110 can be made almost zero. Normally, a space 130 surrounded by the inner tube 121 and each cable core 110 serves as a refrigerant flow path. For example, in the case where the inside of the former 111 is a refrigerant forward path, the space 130 surrounded by the inner pipe 121 and each cable core 110 becomes the refrigerant return path, and the refrigerant is circulated through the superconducting cable.

JP 2006-156328 A (FIG. 5)

  However, in the above superconducting cable, when external damage occurs, a large amount of liquid refrigerant leaks and causes various problems.

  In general, the liquid refrigerant is circulated by pumping the liquid refrigerant with a pump. Therefore, if the heat insulation pipe is damaged by the above-mentioned cable in which the space between the core and the heat insulation pipe is a refrigerant flow path, an opening is formed in the middle of the refrigerant flow path and is pumped by a pump. The coming liquid refrigerant will flow out from the opening. That is, a large amount of cryogenic liquid refrigerant flows out, and there is a risk that a person in the vicinity of the opening may be exposed to danger or an object may be damaged.

  Further, since the liquid refrigerant that has flowed out is exposed to a normal temperature range, it evaporates over time. In particular, when the liquid refrigerant is liquid nitrogen and the outflow / vaporization occurs in a closed space such as a tunnel or a building, a ventilation device is usually provided in such a closed space, but it is still near the outflow point. I would like to eliminate the possibility of temporarily becoming deficient in oxygen.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a superconducting cable line that can reduce the outflow of refrigerant even when the cable is damaged.

  Another object of the present invention is to provide a superconducting cable line in which the vicinity of the outflow portion does not become oxygen deficient even if the refrigerant flows out due to damage to the cable.

  The superconducting cable line of the present invention is a superconducting cable line comprising a core and a heat insulating tube covering the outside thereof. In this line, the core includes a former serving as a refrigerant circulation channel, a superconducting conductor layer provided outside the former, and an insulating layer provided outside the conductor layer. And space is formed between a core and a heat insulation pipe | tube, and the substance in the space is not distribute | circulated, It is characterized by the above-mentioned.

  According to this structure, the substance in space is not distribute | circulated in the space between a core and a heat insulation pipe | tube. Therefore, even if the heat insulating tube is damaged and the opening is opened, the refrigerant circulates in the former inside the insulating layer, so that the refrigerant does not flow out unless the former is damaged. Further, even if the space between the core and the heat insulating pipe is filled with the substance in the space, the amount of the substance flowing out from the heat insulating pipe is limited because the substance in the space is not pumped by the pump.

  As one form of this invention cable line, it is mentioned that the said refrigerant | coolant is liquid air.

  If the refrigerant is liquid air, the refrigerant flowing out is liquid air even if the cable is severely damaged to form an opening in the former. Therefore, even if liquid air flows out and is vaporized, it can be avoided that the vicinity of the outflow portion is in an oxygen deficient state.

  As one form of this invention cable line, it is mentioned that the substance in space is a liquid.

  If there is a liquid in the space between the core and the heat insulating tube, this liquid is located in the heat insulating tube, so it is usually in a cryogenic state close to liquid air and can perform the same function as the refrigerant that cools the superconducting conductor layer. it can. Also, this liquid is not circulated. In other words, since this liquid is not pumped by the pump, even if the heat insulation pipe is damaged and an opening is formed, the liquid does not flow out from the opening to the outside one after another, and the amount of outflow can be reduced. . Furthermore, if this liquid is insulating, it can contribute to the stabilization of the insulating properties of the superconducting cable.

  As one form of this invention cable line, it is mentioned that the said substance in space is insulating gas.

  According to this configuration, the insulating property of the superconducting cable can be stabilized by filling the space between the core and the heat insulating tube with the insulating gas. Moreover, since this insulating gas is not circulated, even if the heat insulating tube is damaged and an opening is formed, the amount of outflow from the opening is limited.

  As one form of the cable line of the present invention, when the substance in the space is an insulating gas, the insulating gas is a gas that does not liquefy at the refrigerant temperature.

  The space between the heat insulation pipe and the core is separated from the normal temperature range by the heat insulation pipe, so it becomes extremely low temperature close to the refrigerant temperature, but even in this state, the insulating gas inside does not liquefy. Higher heat insulating properties can be obtained compared to the case.

  As one form of this invention cable line, it is mentioned that the circulation path of the said refrigerant | coolant is comprised with the metal pipe.

  If the circulation path of the refrigerant is a metal pipe, it has excellent thermal conductivity, so that the superconducting wire on the outer periphery of the former can be efficiently cooled, and leakage of the refrigerant from the passage can be reliably prevented.

  As one form of this invention cable line, providing a cushion layer between the said former and a superconducting conductor layer is mentioned.

  According to this configuration, when the cable is cooled during the operation of the line, at least a part of the thermal contraction of the superconducting conductor layer can be absorbed by the cushion layer, and it is possible to suppress an excessive tension from acting on the superconducting wire. .

  As one form of this invention cable line, it is mentioned that the said superconducting cable line is a DC cable line.

  In the case of a DC cable line, it can be suitably used as a power supply line such as a train, or a power supply line provided between facilities or in a facility. In particular, the single-core cable line is suitable in that it easily constitutes the refrigerant flow path in the former.

  One form of the cable line of the present invention is that it is laid in a substantially closed space.

  Even if the cable is damaged in the substantially closed space and the refrigerant flows out, the closed space does not become deficient because the refrigerant is air. Substantially closed spaces include buildings that are completely separated from the inside and outside, as well as spaces that are difficult to fully ventilate inside even if they are partially open, such as tunnels. .

  According to the superconducting cable line of the present invention, the refrigerant flow path is only inside the insulating layer, and no material in the space is circulated in the space outside the insulating layer. The amount of the substance in the space that flows out is limited, and the refrigerant does not leak immediately outside the heat insulating tube.

  Embodiments of the present invention will be described below.

  A superconducting cable including a core and a heat insulating tube is used for the superconducting cable line of the present invention. Here, each component of the line will be described in detail with reference to FIG. 1, taking a DC superconducting cable line as an example.

[Superconducting cable]
The core 10 is a member that is housed in the heat insulating tube 20 and constitutes a power transmission path. FIG. 1 shows a single-core superconducting cable 100S. The core 10 includes a former 11, an inner superconducting conductor layer 12, and an insulating layer 13 in order from the inner side. In FIG. 1, an outer superconducting conductor layer 14 and a protective layer 15 are further provided in this order. A cushion layer 16 is provided between the former 11 and the inner superconducting conductor layer 12.

<Refrigerant circulation flow path>
First, the former 11 constitutes a refrigerant circulation channel 11A. Therefore, the form of the former 11 is preferably a pipe. In the case of a pipe, it is preferable to use a corrugated pipe in consideration of flexibility. In particular, if the pipe has no hole communicating with the inside and the outside, the refrigerant is reliably prevented from coming out of the former 11, and the space 30 formed between the core 10 and the heat insulating pipe 20 and the refrigerant flow path 11A are connected. It can be reliably isolated.

  On the other hand, in the case of a pipe or spiral band having holes communicating inside and outside, the refrigerant goes out of the former 11, is impregnated in the insulating layer 13, and further reaches the outside of the core 10. Even in that case, since the refrigerant reaching the outside of the core 10 is not circulated, even if the heat insulating pipe 20 is damaged and leaks to the outside, a relatively small outflow amount is sufficient. Whether the form of the former 11 is a pipe or a spiral band, the material is preferably a metal. Specific examples include stainless steel, copper (copper alloy), steel, and aluminum (aluminum alloy). In particular, when the former 11 is used as a fault current flow path in the event of a cable fault, it is preferable to form the former 11 by configuring the outside of the refrigerant passage with a highly conductive normal conductive conductor such as copper.

  As the refrigerant, liquid nitrogen or liquid air can be suitably used. In particular, liquid air is preferable if the installation location of the superconducting cable line is substantially a closed space, and liquid nitrogen can also be used if the installation location is an open space. Usually, the refrigerant is circulated in the former by a cooling mechanism including a pump and a refrigerator.

<Space between core and insulation pipe>
Since the outer diameter of the core 10 is smaller than the inner diameter of the heat insulating tube 20, a space 30 is formed between the core 10 and the heat insulating tube 20. Even if a substance in the space such as liquid or gas exists in the space 30, the substance in the space may not be distributed.

  For example, if the former 11 is formed of a metal pipe having no hole communicating with the inside and outside, no refrigerant is present in the space 30 between the core 10 and the heat insulating pipe 20. In this case, the space 30 may be filled with a liquid or a gas. When the substance in the space is a liquid, it may be the same substance as the refrigerant or a substance different from the refrigerant. The substance in the liquid space is preferably a substance that is liquid at the refrigerant temperature. For example, when the refrigerant is liquid air, liquid air or liquid nitrogen can be selected as the substance in the space. Even if liquid nitrogen or liquid air flows out to the outside of the heat insulating tube 20, the amount of outflow is limited and the influence on the external environment is small because it is not circulated. When the material in the space is a gas, an insulating gas such as nitrogen gas is used. On the other hand, if the former 11 is capable of communicating with the inside and outside, the refrigerant in the former 11 is impregnated into the insulating layer 13 and further filled into the space 30 between the core 10 and the heat insulating tube 20. Even in such a case, the refrigerant in the space 30 is not distributed because it is substantially separated from the inside of the former 11 by the insulating layer 13 or the like. By filling the space 10 with sufficient clearance between the core 10 and the heat insulating tube 20, the space 30 can be easily filled.

  Further, when the substance in the space is a gas, the inside of the space 30 may be a negative pressure. For example, even if nitrogen gas is filled in the space 30, the space 30 is cooled to a considerably low temperature by the refrigerant in the former 11, so that the nitrogen gas contracts and the space 30 becomes negative pressure. Is assumed. This configuration is suitable when the pressure in the space 30 is negative, or when the operating voltage of the cable is low (for example, about 7 kV or less).

  When the refrigerant is liquid air and the substance in the space is a gas, an element that does not liquefy at the refrigerant temperature, such as helium or neon, can be used as the gas. If the substance does not liquefy at the refrigerant temperature, the space 30 can be filled in a gas state, and higher heat insulation can be realized as compared with the case where the substance in the space is liquid.

<Inner superconducting conductor layer>
For the inner superconducting conductor layer 12, it is conceivable to use a superconducting wire in which a filament made of an oxide superconductor is wrapped in a stabilizing material or a thin film superconducting wire. An example of the former is a Bi-based superconducting wire produced by a powder-in-tube method, and an example of the latter is a YBCO-based thin film superconducting wire. In either case, the inner superconducting conductor layer 12 is formed by being spirally wound around the former 11 in multiple layers.

<Insulating layer>
As the insulating layer 13, kraft paper, composite paper in which kraft paper and plastic tape are laminated, plastic tape, or the like can be used. The insulating layer 13 can be formed by winding these alone or in combination of a plurality of types and winding them outside the inner superconducting conductor layer 12.

<Outer superconducting conductor layer>
An outer superconducting conductor layer 14 is formed outside the insulating layer 13. The outer superconducting conductor layer 14 can also be formed by spirally winding a superconducting wire similar to the inner superconducting conductor layer 12. In the case of this example, since it is a DC cable, the inner superconducting conductor layer 12 can be used as a current outgoing path, and the outer superconducting conductor layer 14 can be used as a current return path. In the case of an AC cable, the outer superconducting conductor layer 14 can be used as a shield layer.

<Protective layer>
The protective layer 15 secures insulation between the current flowing in the outer superconducting conductor layer 14 and the heat insulating tube 20, and mechanically protects the outer superconducting conductor layer 15. For the protective layer 15, a material having an insulating property and excellent in cushioning properties to some extent can be suitably used.

<Insulated pipe>
On the other hand, the heat insulating tube 20 covers the outside of the core 10 over the entire length to ensure heat insulation. Here, a heat insulating pipe having a double structure of the inner pipe 21 and the outer pipe 22 is used. A radiation heat insulating material (not shown) is disposed between the inner tube 21 and the outer tube 22, and the space between the tubes 21 and 22 is evacuated.

[Other configurations]
<Cushion layer>
Further, in this example, a cushion layer 16 is formed between the former 11 and the inner superconducting conductor layer 12. A material that is excellent in cushioning properties in the thickness direction can be suitably used for the cushion layer. The cushion layer 16 absorbs heat shrinkage of the inner superconducting conductor layer 12 when the cable is cooled, and suppresses excessive tension from acting on the superconducting wire forming the conductor layer 12.

<Connection part, terminal part, circulation cooling mechanism>
In addition to the superconducting cable 100S, the intermediate connection portion 40, the terminal portion 50, and the circulation cooling mechanism 60 are used for forming the cable line, as shown in FIG. The intermediate connection unit 40 is used to connect a plurality of superconducting cables 100S having the unit length of the above configuration. The terminal unit 50 has a configuration for taking out electric power from the end of a plurality of connected superconducting cables 100S to the room temperature side. The circulation cooling mechanism 60 circulates liquid air in the former of the superconducting cable 100S. More specifically, a refrigerator 61, a pump 62, and a return pipe 63 are provided. For example, the interior of the former is used as the forward path of liquid air, and liquid air is pumped into the former from the terminal portion 50S at one end of the line via the refrigerator 61 and the pump 62. Then, the liquid air is returned to the refrigerator 61 again through the return pipe 63 through the terminal portion 50E on the other end side, and the liquid air is circulated in the same manner.

  In addition, as shown in FIG. 3, a configuration in which two superconducting cables 100G and 100R are arranged in parallel, the refrigerant flow path of one cable 100G is used as the refrigerant forward path, and the refrigerant flow path of the other cable 100R is used as the refrigerant return path Is also suitable.

<Types of cable lines>
Although the superconducting cable line of the present invention has been described by taking a DC line as an example, it can also be used for an AC line. In that case, the outer superconducting conductor layer functions as a shield layer.

  An example of the superconducting cable line shown in the above embodiment will be described. The basic configuration of this embodiment is the same as FIG. Hereinafter, the configuration of the superconducting cable constituting the line will be mainly described.

  In the first embodiment, the former 11 is composed of a stainless corrugated pipe. The pipe does not have a hole communicating with the inside and outside. A Bi2223-based superconducting wire is spirally wound on the outer side through a cushion layer 16 of kraft paper to form the inner superconducting conductor layer 12. Next, the insulating layer 13 is formed on the conductor layer 12 by winding PPLP (registered trademark of Sumitomo Electric Industries, Ltd.) laminated with polypropylene and kraft paper around the outer peripheral side of the inner superconducting conductor layer 12. Subsequently, the same superconducting wire as the inner superconducting conductor layer 12 is spirally wound outside the insulating layer 13 to form the outer superconducting conductor layer 14. Furthermore, kraft paper is wound around the outer superconducting conductor layer 14 to form the protective layer 15. Subsequently, the single core with the above configuration was housed in a heat insulating tube 20 having a vacuum double structure to obtain a superconducting cable 100S. The space 30 between the core 10 and the heat insulating tube 20 is filled with liquid nitrogen. With this filling, the insulating layer 13 is impregnated with liquid nitrogen, but the space 30 is only filled with liquid nitrogen and is not circulated. The inner tube 21 and the outer tube 22 of the heat insulating tube 20 are each composed of a stainless corrugated pipe, and super insulation (trade name) is used as the radiant heat insulating material.

  If a superconducting cable line is configured using such a cable, liquid air serving as a refrigerant flows only in the former 11, and liquid nitrogen existing outside the former 11 does not flow at all. Therefore, even if the heat insulating tube 20 is damaged, the liquid nitrogen is not pumped by the circulation mechanism, so the amount of liquid nitrogen leaking from the space 30 is limited. Even if the cable is damaged to reach the former 11, what leaks is liquid air, and even if vaporized, the surrounding environment is hardly affected.

  As a modification of this example, the filling material in the space 30 may be gaseous nitrogen instead of liquid nitrogen. In this case, even if the heat insulating tube 20 is damaged, the temperature of the gas flowing out of the space 30 is higher than that of liquid nitrogen, and even if the effluent gas comes into contact with the surrounding people, it is safer than that of liquid nitrogen. . Further, since the space 30 is made of gaseous nitrogen, it is possible to obtain higher heat insulation characteristics than in the case of liquid nitrogen.

  Next, an embodiment of the present invention using a spiral steel strip for the former will be described. The basic configuration of this embodiment is the same as that shown in FIG. Hereinafter, the difference from the first embodiment will be mainly described.

  In this example, the biggest difference is that a spiral steel strip is used for the former 11. Along with this difference, the liquid air advances to the outside of the former 11, so that the insulating layer 13 is impregnated, and the space 30 between the core 10 and the heat insulating pipe 20 is also filled. However, since the liquid air in the former 11 and the liquid air in the space 30 are substantially separated via the inner (outer) superconducting conductor layer 12 (14) and the insulating layer 13, the liquid air in the former 11 is separated. Only the liquid air in the space 30 is not circulated.

  In the case of this example, if the heat insulating tube 20 is damaged, the liquid air in the space 30 flows out. However, since the liquid air in the space 30 is not pumped by the circulation mechanism, the liquid air does not flow out from the damaged portion, and the outflow amount is limited. In addition, since the liquid that flows out is air, the influence on the surrounding environment is very small even if it flows out. Even if the former 11 is damaged, since the air that flows out of the former 11 is liquid air, it is possible to avoid the lack of oxygen near the outflow site.

  In addition, this invention is not limited to said Example, A various change is possible. For example, although a single-core DC cable has been described in the above embodiment, a three-core superconducting cable or an AC cable can be used.

  The superconducting cable line of the present invention can be used as a power transportation path. In particular, it can be suitably used when a substantially closed space such as a general building is included in the laying path.

It is sectional drawing which shows an example of the superconducting cable used for this invention track | line. It is a schematic block diagram which shows the Example which concerns on this invention track | line. It is a schematic block diagram which shows another Example concerning this invention track | line. It is sectional drawing of the superconducting cable used for the conventional track.

Explanation of symbols

100S single-core superconducting cable
10 Cable core
11 Former 11A Circulating channel 12 Inner superconducting conductor layer 13 Insulating layer
14 Outer superconducting conductor layer 15 Protective layer 16 Cushion layer
20 Heat insulation pipe 21 Inner pipe 22 Outer pipe 23 Anticorrosion layer
30 spaces
40 Intermediate connection 50, 50S, 50E Terminal
60 Circulation cooling mechanism 61 Refrigerator 62 Pump 63 Return piping
100G, 100R superconducting cable
100P 3-core superconducting cable
120 Heat insulation pipe 121 Inner pipe 122 Outer pipe 123 Anticorrosion layer
110 cable core
111 Former 112 Superconducting conductor layer 113 Insulating layer 114 Shield layer
115 Protective layer
130 space

Claims (9)

A superconducting cable line comprising a core and a heat insulating tube covering the outside,
The core is
A former that serves as a circulation path for the refrigerant;
A superconducting conductor layer provided outside the former;
An insulating layer provided outside the conductor layer,
A superconducting cable line characterized in that a space is formed between the core and the heat insulating tube, and no substance in the space is circulated.   The superconducting cable line according to claim 1, wherein the refrigerant is liquid air.   3. The superconducting cable line according to claim 1, wherein the substance in the space is a liquid.   3. The superconducting cable line according to claim 1, wherein the substance in the space is an insulating gas.   5. The superconducting cable line according to claim 4, wherein the insulating gas is a gas that does not liquefy at a refrigerant temperature.   6. The superconducting cable line according to claim 1, wherein the circulation path of the refrigerant is constituted by a metal pipe.   7. The superconducting cable line according to claim 1, further comprising a cushion layer between the former and the superconducting conductor layer.   The superconducting cable line according to any one of claims 1 to 7, wherein the superconducting cable line is a DC cable line.   The superconducting cable line according to any one of claims 2 to 8, wherein the superconducting cable line is laid in a substantially closed space.

Images