JP6560733B2 - Superconducting cable - Google Patents

Description

  The present invention relates to a superconducting cable.

  Conventionally, a superconducting cable using a superconducting wire that becomes a superconducting state at an extremely low temperature as a conductor is known. The superconducting cable is expected as a power cable capable of transmitting a large current with a low loss, and is being developed for practical use.

  The superconducting cable has a structure in which a single-core or multiple-core cable core is accommodated in a heat insulating tube. The cable core includes, for example, a former, a superconducting conductor layer, an electrical insulating layer, a cable shield layer, and a protective layer in order from the center. The heat insulation pipe includes an inner pipe (hereinafter referred to as “heat insulation inner pipe”) in which the cable core is accommodated and filled with a refrigerant (for example, liquid nitrogen), and an outer pipe (hereinafter referred to as “heat insulation outer pipe”) covering the outer periphery of the heat insulation inner pipe. It is a double-pipe structure having

  The heat insulating inner pipe and the heat insulating outer pipe are generally formed by corrugated pipes, respectively, and can be laid and bent freely in the ground as a superconducting cable together with a cable core disposed inside.

  A space between the heat insulating inner tube and the heat insulating outer tube is in a vacuum state to prevent heat from entering due to heat conduction from the outside. In addition, a multilayer heat insulating material is provided between the heat insulating inner tube and the heat insulating outer tube to prevent heat from entering due to radiation from the outside.

  The multilayer heat insulating material is constituted by wrapping a plurality of heat insulating sheets in which a polyester net or a nonwoven fabric is layered on an aluminum vapor-deposited polyester film on the outer periphery of a heat insulating inner tube. For example, Patent Document 1 discloses a multilayer heat insulating material configured by laminating a layer of an Al (aluminum) sheet and a spacer so as to surround a superconducting magnet that is a cryogenic device in a vacuum vessel. Yes.

JP 2012-151181 A

  By the way, the conventional multilayer heat insulating material is comprised by winding the tape-like layer of the same thickness which consists of an Al sheet and a spacer on the outer periphery of a heat insulation inner pipe, and piled up it. Moreover, it comprises by winding the Al sheet | seat and spacer which comprise each layer so that it may overlap in order from the inner side so that each layer may be formed in the outer peripheral side of a core.

  In either case, the tape-shaped layer, or each layer of the Al sheet and the spacer constituting the layer, has a difference in diameter when the outermost layer and the innermost layer are wound. The heat flux from the part becomes large, and there is a fear that the heat insulating effect as the multilayer heat insulating material is reduced.

  The objective of this invention is providing the superconducting cable which can prevent the heat insulation fall by providing a heat insulating material suitably in the outer periphery of the inner tube | pipe of a heat insulation pipe | tube without slack.

One aspect of the superconducting cable of the present invention is:
A superconducting cable core having a superconducting wire, and
A heat insulating pipe having a double pipe structure that accommodates the superconducting cable core and has an inner pipe and an outer pipe;
With
The heat insulation pipe has a vacuum layer between the inner pipe and the outer pipe,
Around the outer periphery of the inner tube, a multilayer heat insulating material formed by laminating a plurality of heat insulating materials is wound ,
In the plurality of heat insulating materials, the outer layer heat insulating material is thicker than the inner layer heat insulating material.

  According to the present invention, it is possible to prevent a decrease in heat insulation properties by suitably providing a heat insulating material on the outer periphery of the inner tube of the heat insulating tube without slack.

It is a schematic sectional drawing of the superconducting cable of one embodiment which concerns on this invention. It is a figure which shows an example of a structure of the cable core of a superconducting cable. It is a figure where it uses for description of the structure of the multilayer heat insulating material of the superconducting cable. It is a partial side cross section which shows the structure of the heat insulating material in the multilayer heat insulating material of the superconducting cable. It is a fragmentary sectional side view which shows the structure of the modification of the heat insulating material in the multilayer heat insulating material of the superconducting cable. It is a fragmentary sectional side view of the superconducting cable which shows the structure of the multilayer heat insulating material to which the modification of a heat insulating material is applied.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Overall configuration of superconducting cable>
FIG. 1 is a schematic cross-sectional view of a superconducting cable according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating an example of a configuration of a cable core of the superconducting cable.

  A superconducting cable 100 shown in FIG. 1 includes, for example, a cable core 110 having a superconducting layer composed of a superconducting wire, a heat insulating tube (double tube) 120, a protective layer (not shown), and the like in order from the center.

  For example, as shown in FIG. 2, the cable core 110 includes, in order from the center of the cable core 110, a former 111, an electrically insulating layer formed by a holding tape 112, a superconducting conductor layer formed by a superconducting wire 113, an electrically insulating layer formed by a holding tape 114, and It has a superconducting conductor layer made of superconducting wire 115.

  The former 111 has a cylindrical shape or a columnar shape, and is formed in a columnar shape from a stranded wire of Cu (copper) here. In the case of the cylindrical shape, the inside is filled with a refrigerant such as liquid nitrogen. A presser tape 112 made of a nonwoven fabric is wound around the outer periphery of the former 111.

On the outer periphery of the presser tape 112, a tape-shaped first superconducting wire 113 constituting the first superconducting layer is wound in a spiral shape with a certain predetermined interval between each tape in the circumferential direction. ing. A presser tape 114 made of a nonwoven fabric is wound around the outer periphery of the first superconducting wire 113. Each of the presser tapes 112 and 114 is configured as a layered electrical insulating layer by winding one non-woven fabric in a spiral shape without a gap. Note that the tape-like second superconducting wire 115 constituting the second superconducting conductor layer is spirally provided on the outer periphery of the presser tape 114 at a predetermined interval in the circumferential direction, like the first superconducting wire 113. It is wound in a shape. On the outer periphery of the second superconducting wire 115, a non-illustrated presser tape, like the presser tapes 112 and 114, is wound with a single non-woven fabric spirally without a gap. Here, ten superconducting tapes per layer are wound spirally at a predetermined interval. In addition, as a layer by the superconducting wires 113 and 115, for example, ten superconducting wires having a thickness of 0.1 mm and a width of 5 mm are wound at a twist pitch of 250 mm. As the presser tapes 112 and 114, for example, a non-woven fabric having a thickness of 0.2 mm and a width of 45 mm is wound in half wrap (that is, half of the tape width is wound in an overlapping manner). In addition, as a material of the superconducting wires 113 and 115, various conventionally proposed superconducting materials can be used. Here, the superconducting wire 113, 115 via an intermediate layer on the _substrate, REBa y _Cu 3 _{O z} system (RE is Y, Nd, Sm, Eu, 1 or more elements selected from Gd, and Ho Where y ≦ 2 and z = 6.2 to 7.) A superconducting layer is formed which is a high-temperature superconducting thin film.

  Although not shown in FIGS. 1 and 2, in both terminal portions of the superconducting cable 100, the cable core 110 is stepped, and each layer is exposed in order from the tip side of each terminal portion. A conductor connection terminal that is electrically connected to the superconducting layer may be disposed on the outer periphery of the superconducting layer made of the superconducting wire 115 of the cable core 110. Further, a cable shield layer (not shown) is provided outside the superconducting layer made of the superconducting wire 115, and a shield connection terminal electrically connected to the cable shield layer is arranged on the outer periphery of the cable shield layer. Good.

  For example, an electric field relaxation layer such as a stress cone may be disposed on the outer periphery of the electrical insulating layer located between the conductor connection terminal and the shield connection terminal. Although not shown in FIGS. 1 and 2, the terminal portion of the superconducting cable 100 is inserted into a refrigerant tank in the terminal unit, and in this refrigerant tank, the former 111 of the cable core 110 and the superconducting wires 113 and 115 are used. The superconducting layer is electrically connected to the conductor lead portion through the conductor connection terminal.

  The heat insulating tube 120 has a double tube structure including an inner heat insulating inner tube 130 and an outer heat insulating outer tube 140, and is disposed on the outer periphery of the cable core 110. The heat insulating pipe 120 has a multilayer heat insulating material 150 on the outer periphery of the heat insulating inner pipe 130. A protective layer (anticorrosion layer) (not shown) is formed on the outer periphery of the heat insulating tube 120.

  The heat insulating inner tube 130 and the heat insulating outer tube 140 are formed of a cylindrical body having conductivity such as stainless steel or aluminum. Here, the inner diameters are different from each other, and are constituted by corrugated tubes arranged concentrically.

The heat insulation inner pipe 130 accommodates the cable core 110 and is filled with a refrigerant (for example, liquid nitrogen N ₂ (l)) during operation. Thereby, the superconducting conductor layer is maintained in a superconducting state. A space between the heat insulating inner tube 130 and the heat insulating outer tube 140 is kept in a vacuum state during operation for heat insulation. That is, the vacuum layer 122 is formed between the heat insulating inner tube 130 and the heat insulating outer tube 140.

  In this vacuum layer 122, the multilayer heat insulating material 150 is provided so as to cover the heat insulating inner tube 130.

<Configuration of multilayer heat insulating material 150>
The multilayer heat insulating material 150 is a so-called super insulation (SI), and prevents heat penetration due to radiation from the outside.

  3 is a diagram for explaining the structure of the multilayer heat insulating material of the superconducting cable, and FIG. 3A is a diagram schematically showing a plurality of heat insulating materials 161 to 164 constituting the multilayer heat insulating material 150, and FIG. These are the fragmentary sectional views which show the state by which the multilayer heat insulating material 150 comprised by the heat insulating materials 161-164 was provided in the outer periphery of the heat insulation inner tube | pipe 130. FIG.

  The multilayer heat insulating material 150 is configured by laminating a plurality of heat insulating materials 161 to 164. In these layers to be laminated, the thickness of the heat insulating material constituting the outer layer is larger than the thickness of the heat insulating material of the inner layer. In the present embodiment, the heat insulating material 164 constituting the outermost layer is thicker than the innermost heat insulating material 161.

  In the multilayer heat insulating material 150 of the present embodiment, the thickness of each layer, that is, the thickness of the heat insulating materials 161 to 164 constituting each layer is different, and the thickness is increased in the order of lamination from the cable core 110 side toward the outermost layer side. Is getting thicker.

  The heat insulating materials 161 to 164 are sheet-like, and each include a metal vapor deposition sheet 171 obtained by vapor-depositing a metal film on a resin, and nonwoven fabric sheets 181 to 184 provided on the metal vapor deposition sheet 171. Only the thicknesses of the heat insulating materials 161 to 164 of the present embodiment are different, and specifically, the thicknesses of the respective nonwoven fabric sheets 181 to 184 are different for each of the heat insulating materials 161 to 164. Moreover, the heat insulating materials 161-164 are provided in contact with the metal vapor deposition sheet 171 of each heat insulating material 161-164 in this Embodiment.

  As shown in FIGS. 3A and 3B, the multilayer heat insulating material 150 is configured such that the nonwoven fabric sheets 181 to 184 of the heat insulating material 161 to the heat insulating material 164 gradually increase in thickness in the order of lamination from the cable core 110 side. The

  Each heat insulating material 161-164 provides the same metal vapor deposition sheet | seat 171 with the nonwoven fabric sheets 181-184 from which thickness differs, respectively. Below, the fundamental structure of a heat insulating material is demonstrated using the heat insulating material 161 which comprises an innermost layer.

  As shown in FIG. 4, the metal vapor deposition sheet 171 includes a resin layer 171a, a metal layer 171b, and a metal layer 171c.

  The resin layer 171a is formed of a thermoplastic resin. For example, polyester, polyethylene, polypropylene, or polyamide can be used as the thermoplastic resin. It is desirable to use a polyester-based material from the viewpoints of melting point, water absorption, metal vapor deposition, tear strength, weight, cost, and the like. The resin layer 171a suppresses heat conduction.

  The metal layer 171b is disposed on one surface of the resin layer (here, the front surface of the resin layer), and the metal layer 171c is the other surface of the resin layer 171a (here, the front and back surfaces of the resin layer 171a). Are arranged on the back surface side. In this embodiment, the metal layer 171b and the metal layer 171c are formed by vapor-depositing a metal on both surfaces of the resin layer 171a, but may be formed only on one surface of the resin layer 171a.

  As a metal constituting the metal layer 171b and the metal layer 171c, for example, aluminum, gold, silver, copper, nickel, or the like can be used. From the viewpoints of vertical infrared reflectance, easiness of vapor deposition, uniformity of deposited film, weight, cost, etc., it is desirable to use aluminum as the metal. The metal layer 171b and the metal layer 171c reflect radiant heat. The method for depositing metal on the resin layer 171a is not particularly limited, but may be performed by electrothermal heating, sputtering, ion plating, ion beam, or the like using a continuous or batch type vacuum vapor deposition machine. The thicknesses of the metal layer 171b and the metal layer 171c are not particularly limited, but are preferably 100 angstroms or more and 1000 angstroms or less. By setting the thickness of the metal layer 171b or the metal layer 171c to 100 angstroms or more, the amount of infrared rays transmitted from the metal layer 171b or the metal layer 171c can be further suppressed, and the deterioration of the heat insulation characteristics can be further suppressed. In addition, by increasing the thickness of the metal layer 171b and the metal layer 171c to 1000 angstroms or less, an increase in the thermal conductivity in the metal layer 171b and the metal layer 171c is further suppressed, and generation of cracks due to bending or the like during construction is prevented. It can be suppressed more.

  The thickness of the metal vapor deposition sheet 171 is desirably 3 μm or more and 100 μm or less. The thickness of the metal vapor deposition sheet 171 is more desirably 6 μm or more and 50 μm or less. By setting the thickness of the metal vapor deposition sheet 171 to 3 μm or more, generation of wrinkles in the metal layer 171b or the metal layer 171c can be further suppressed. By setting the thickness of the metal vapor deposition sheet 171 to 6 μm or more, generation of wrinkles in the metal layer 171b or the metal layer 171c can be further suppressed. Moreover, by making the thickness of the metal vapor deposition sheet 171 100 μm or less, an increase in weight can be further suppressed, an increase in contact area with the nonwoven fabric sheet 181 can be further suppressed, and a decrease in heat insulation characteristics can be further suppressed. Moreover, by making the thickness of the metal vapor deposition sheet 171 50 μm or less, an increase in weight can be further suppressed, an increase in the contact area with the nonwoven fabric sheet 181 can be further suppressed, and a decrease in heat insulation characteristics can be further suppressed.

  The thicknesses of the metal layer 171b and the metal layer 171c are measured by, for example, measuring a sheet resistance value with a four-point low resistance meter (Dia Instruments Lorester EP) and using the sheet resistance value and the metal film specific resistance value as a deposited film. It can be obtained by calculating the thickness. In addition, the thickness of the metal vapor deposition sheet 171 can be measured by the method of 6.1 clause of JISL1913.

  The metal vapor deposition sheet 171 of this embodiment is a sheet formed by vapor-depositing aluminum to be the metal layers 171b and 171c on the front and back surfaces of a polyethylene terephthalate (PET) film as the resin layer 171a. It is.

  Each of the heat insulating materials 161 to 164 has a metal vapor deposition sheet 171 having the same thickness.

  Nonwoven fabric sheet 181 has a resin layer containing resin fibers. The nonwoven fabric sheet 181 may have a structure in which resin fibers are stacked in multiple layers. The resin fiber may be formed of a thermoplastic resin. As the flexible resin, for example, polyester, polyethylene, polypropylene, polyamide, or the like can be used. From the viewpoint of melting point, water absorption, stretchability, tear strength, weight, cost, etc., it is desirable to use a polyester resin. The nonwoven fabric sheet 181 suppresses heat conduction.

  Polyester mesh is used for the nonwoven fabric sheet of the present embodiment, and in each of the heat insulating materials 161 to 164, polyester meshes having different thicknesses are used as the nonwoven fabric sheets 181 to 184, respectively, and are provided integrally with the metal deposition sheet 171. The heat insulating materials 161 to 164 are configured. In the present embodiment, the thickness of the nonwoven fabric sheets 181 to 184 in each of the heat insulating materials 161 to 164 is greater in the heat insulating material 164 disposed on the outer layer side than the heat insulating material 161 disposed on the inner layer side of the multilayer heat insulating material 150. It is configured to be thick.

Density of the nonwoven fabric sheet (mass per unit area) is, 2 g / ^{m 2} or more 15 g / ^{m 2} or less. The density (weight per unit area) of the nonwoven fabric sheet is more preferably 3 g / m ² or more and 15 g / m ² or less. In order to prevent heat conduction, it is desirable that the density is low, that is, the basis weight is light, and the density of the nonwoven fabric sheet is more desirably 3 g / m ² or more and 10 g / m ² or less. If the density of a nonwoven fabric sheet shall be ² g / m <2> or more, since the metal vapor deposition sheets which pinch | interpose a nonwoven fabric sheet will become more difficult to contact, it is preferable. If the density of a nonwoven fabric sheet shall be 3 g / m < ² > or more, since the metal vapor deposition sheets which pinch | interpose a nonwoven fabric sheet will become more difficult to contact, it is preferable. If the density of the nonwoven fabric sheet is 15 g / m ² or less, the heat insulating properties are improved, which is preferable. In addition, the density (weight per unit area) of a nonwoven fabric sheet can be measured by the method of 6.2 clause of JISL1913.

<Method for forming multilayer heat insulating material 150>
In the superconducting cable 100 configured as described above, the multilayer heat insulating material 150 is provided by sequentially winding the heat insulating materials 161, 162, 163, and 164 around the outer periphery of the heat insulating inner tube 130 as shown in FIG.

  The heat insulating materials 161 to 164 constituting each layer of the multilayer heat insulating material 150 are made of the non-woven fabric sheet 184 of the heat insulating material 164 serving as the outermost layer, rather than the thickness of the non-woven fabric sheet 181 on the heat insulating material 161 side constituting the layer on the cable core 110 side. The thickness is thicker. Therefore, when the respective layers of the multilayer heat insulating material 150 are wound around the outer periphery of the heat insulating inner tube 130 in order so that the heat insulating materials 161 to 164 are laminated from the cable core 110 side, the heat insulating material is not loosened. 161-164 can be wound sequentially.

<Effects of superconducting cable 100>
According to superconducting cable 100 of the present embodiment, a superconducting cable core 110 having superconducting wires 113 and 115, a superconducting cable core 110, a double tube structure having a heat insulating inner tube 130 and a heat insulating outer tube 140 are accommodated. And a heat insulating tube 120. The heat insulating tube 120 has a vacuum layer 122 between the heat insulating inner tube 130 and the heat insulating outer tube 140, and a multilayer heat insulating material 150 formed by laminating a plurality of heat insulating materials 161 to 164 is provided on the outer periphery of the heat insulating inner tube 130. It is done.

  In the plurality of heat insulating materials 161 to 164, the outermost heat insulating material 164 is thicker than the innermost heat insulating material 161. Moreover, in the multilayer heat insulating material 150, the thickness of the several layer each comprised by the several heat insulating materials 161-164 is thick in the order laminated | stacked from the cable core 110 side. Nonwoven fabric sheets in each of the heat insulating materials 161 to 164 so that the interval between the metal vapor deposition sheets 171 in each of the heat insulating materials 161 to 164 laminated on the outer periphery of the heat insulating inner tube 130 increases from the innermost layer side to the outermost layer side. It can be said that the thicknesses of 181 to 184 are different.

  For this reason, in the superconducting cable 100, the outer periphery of the heat insulation inner pipe 130 can be suitably provided without winding slack when the heat insulation materials 162, 163, and 164 are wound in order from the heat insulation material 161 as the innermost layer.

  Therefore, the heat flux from the winding slack portion does not increase, and the heat insulating property as the multilayer heat insulating material 150 can be prevented from being lowered.

<Modification of insulation material>
In a plurality of sheet-like heat insulating materials (161 to 164) constituting the multilayer heat insulating material 150, a silicon oxide layer made of silicon oxide is provided between the metal vapor-deposited sheet 171 on which a metal film is vapor-deposited and the nonwoven fabric sheets 181 to 184. You may have. Silicon oxide is known to exhibit a high barrier property that prevents permeation of water vapor and oxygen.

FIG. 5 is a partial cross-sectional view showing the structure of a modification of the heat insulating material in the multilayer heat insulating material 150 of the superconducting cable according to the present embodiment.
The heat insulating material 161A shown in FIG. 5 is in the form of a sheet, a metal vapor-deposited sheet 171 in which a metal film is vapor-deposited on a resin, a non-woven sheet 181A provided on the metal vapor-deposited sheet 171, and these metal vapor-deposited sheet 161A and non-woven sheet A silicon oxide layer 190 is provided between 181A and 181A.
The silicon oxide layer 190 is provided in contact with each of the metal vapor deposition sheet 161A and the nonwoven fabric sheet 181A, but may be provided in contact with at least one of them.

Since the metal vapor deposition sheet 171 and the nonwoven fabric sheet 181A are configured in the same manner as the metal vapor deposition sheet 171 and the nonwoven fabric sheet 181 of the heat insulating material 161, description thereof will be omitted.
The silicon oxide layer 190 may be formed in a layer shape by any silicon oxide of silicon monoxide, silicon dioxide, or silicon suboxide.

The heat insulating material 161A as a modified example is formed of the same material as the nonwoven fabric sheet 181A on the surface (outer layer side) opposite to the surface (outer layer side) on which the silicon oxide layer 190 is provided in the metal vapor deposition sheet 171. The nonwoven fabric sheet for adjustment 186 is provided.
That is, the heat insulating material 161A of the modification 161A is configured by sequentially laminating the metal vapor deposition sheet 171, the silicon oxide layer 190, and the nonwoven fabric sheet 181A on the nonwoven fabric sheet 186 in order.

FIG. 6 is a partial cross-sectional view of a superconducting cable having a multilayer heat insulating material 150A to which a modification of the heat insulating material is applied.
The multilayer heat insulating material 150A includes a heat insulating material 161A and heat insulating materials 162A to 164A having different thicknesses from the heat insulating material 161A.

The heat insulating materials 162A to 164A are obtained by changing only the thickness of the nonwoven fabric sheet 181A in the heat insulating material 161A.
That is, in the heat insulating materials 162A to 164A, the silicon oxide layer 190 and the nonwoven fabric sheets 182A to 184A are laminated on the metal vapor deposition sheet 171 provided in contact with the adjustment nonwoven fabric sheet 186, respectively. In addition, the nonwoven fabric sheet 186 for adjustment of each of the heat insulating materials 162A to 164A may be omitted.
The nonwoven fabric sheets 181A to 184A in the heat insulating materials 161A to 164A are configured to be thicker in the order of the nonwoven fabric sheets 181A, 182A, 183A, and 184A.

  Thereby, in the multilayer heat insulating material 150A, the heat insulating material 161A is provided on the outer periphery of the heat insulating inner tube 130, and the heat insulating material 162A thicker than the heat insulating material 161A is provided on the outer periphery of the heat insulating material 161A. In addition, a heat insulating material 163A thicker than the heat insulating material 162A is provided on the outer periphery of the heat insulating material 162A, and a heat insulating material 164A thicker than the heat insulating material 163A is provided on the outer periphery of the heat insulating material 163A.

  As described above, in the multilayer heat insulating material 150A, the thicknesses of the plurality of layers respectively constituted by the plurality of heat insulating materials 161A to 164A are thicker in the order in which they are stacked from the cable core 110 side. In other words, the multilayer heat insulating material 150A includes a plurality of heat insulating materials 161A such that the interval between the metal vapor deposition sheets 171 of the plurality of heat insulating materials 161A to 164A stacked increases from the inner layer side to the outer layer side of the multilayer heat insulating material 150A. ˜164A has nonwoven fabric sheets 181A to 184A and adjustment nonwoven fabric sheets 186 having different thicknesses.

<Example 1>
The metal vapor-deposited sheet 171 is a 12 μm-thick sheet obtained by vapor-depositing Al on a PET film, and each layer of the multilayer heat insulating material 150 is formed by providing polyester meshes having thicknesses of 100, 150, 200, and 300 μm as nonwoven fabric sheets 181 to 184, respectively. Insulating materials 161 to 164 were manufactured. An aluminum corrugated tube having an outer diameter of 70 m was applied as the heat insulating inner tube 130 in the double-structured heat insulating tube, and an aluminum corrugated tube having an outer diameter of 130 mm was applied as the heat insulating outer tube 140. The superconducting cable core 110 is accommodated in the heat insulating inner tube 130, and heat insulating materials 161 to 164 having different thicknesses are laminated on the outer periphery of the heat insulating inner tube 130 in order from the thin heat insulating material 161 by 1/2 wrap winding. A superconducting cable of Example 1 in which the multilayer heat insulating material 150 was formed and the superconducting cable 100 shown in FIG. 1 was applied was produced. In the multilayer heat insulating material 150 of Example 1, the wrinkles were not generated around the heat insulating materials 161 to 164.

With this cable 100, a horizontal line having a length of 5 m is laid, and the space between the heat insulating inner tube 130 and the heat insulating outer tube 140, which are corrugated tubes, is evacuated so that the degree of vacuum is 8 × 10 ⁻⁴ Pa. Liquid nitrogen is filled in the heat insulation inner pipe 130, and the liquid nitrogen liquid level is monitored with a liquid level gauge, the flow rate of vaporized nitrogen is measured with a mass flow meter, and the amount of heat penetration that has entered the superconducting cable per unit time is measured. Calculated. The heat penetration amount was 0.6 W / m.

<Comparative Example 1>
As in Example 1, the metal vapor-deposited sheet 171 is a sheet of 12 μm thickness obtained by vapor-depositing Al on a PET film, and a 300 μm-thick polyester mesh is provided on the sheet as a non-woven sheet to constitute a layer of a multilayer heat insulating material. Made the material. An aluminum corrugated tube having an outer diameter of 70 m was applied as the heat insulating inner tube 130 in the double-structured heat insulating tube, and an aluminum corrugated tube having an outer diameter of 130 mm was applied as the heat insulating outer tube 140. The superconducting cable core 110 is accommodated in the heat insulating inner tube 130, and the heat insulating material having the same thickness is sequentially laminated on the outer periphery of the heat insulating inner tube 130 by 1/2 wrap winding to form the multilayer heat insulating material 150. A cable was produced. In the multilayer heat insulating material of Comparative Example 1, wrinkles were generated around the heat insulating material. With respect to the superconducting cable of Comparative Example 1, the amount of heat intrusion into the superconducting cable per unit time was calculated in the same manner as in Example 1. The heat penetration amount was 1.5 W / m.
As a result, in Example 1, in the multilayer heat insulating material provided on the outer periphery of the heat insulating inner tube, the thickness of the outermost heat insulating material 164 is thicker than the thickness of the innermost heat insulating material 161 as compared with Comparative Example 1. Thus, by increasing the thickness of the layers sequentially laminated from the innermost layer side, the heat penetration amount as the superconducting cable could be reduced.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. For example, the heat insulating materials 161 to 164 and 161A to 164A in the multilayer heat insulating materials 150 and 150A are Al, PET, Al, non-woven fabric, or non-woven fabric, Al, PET, Al on the outer periphery of the heat insulating inner tube 130 in order from the inside. It is wound so as to be a SiO ₂ layer and a non-woven fabric, but it may be wound in the reverse order. That is, in the heat insulating materials 161 to 164 and 161A to 164A, the nonwoven fabric sheets 181 to 184 and 181A to 184A having different thicknesses may be located on the inner layer side (center side of the superconducting cable) than the metal vapor deposition sheet 171. That is, the heat insulating materials 161 to 164 and 161A to 164A provided with the nonwoven fabric sheets 181 to 184 and 181A to 184A on the metal vapor-deposited sheet 171 may be arranged so that the inner and outer surfaces are reversed by turning over the inner and outer surfaces. Good. These mean the structure similar to the heat insulating material which has the nonwoven fabric sheets 181-184 and 181A-184A under the metal vapor deposition sheet | seat 171. FIG. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The superconducting cable according to the present invention is useful as having an effect of preventing a decrease in heat insulating property by suitably providing a heat insulating material on the outer periphery of the inner tube of the heat insulating tube without slack.

100 Superconducting cable 110 Cable core 111 Former 112, 114 Holding tape 113, 115 Superconducting wire 120 Insulating tube 122 Vacuum layer 130 Insulating inner tube 140 Insulating outer tube 150, 150A Multi-layer insulating material 161, 161A, 162, 162A, 163, 163A, 164, 164A Heat insulating material 171 Metal vapor deposition sheet 171a Resin layer 171b, 171c Metal layer 181, 181A, 182, 182A, 183, 183A, 184, 184A, 186 Nonwoven fabric sheet 190 Silicon oxide layer

Claims (5)

A superconducting cable core having a superconducting wire, and
A heat insulating pipe having a double pipe structure that accommodates the superconducting cable core and has an inner pipe and an outer pipe;
With
The heat insulation pipe has a vacuum layer between the inner pipe and the outer pipe,
Around the outer periphery of the inner tube, a multilayer heat insulating material formed by laminating a plurality of heat insulating materials is wound ,
In the plurality of heat insulating materials, the thickness of the outer layer heat insulating material is thicker than the thickness of the inner layer heat insulating material,
Superconducting cable. The heat insulating material has a metal vapor-deposited sheet in which a metal film is vapor-deposited on a resin, and a non-woven sheet provided on the metal vapor-deposited sheet,
In the heat insulating material of each layer in the multilayer heat insulating material, the metal vapor-deposited sheets have the same thickness, and the thickness of the nonwoven fabric sheet is different.
The superconducting cable according to claim 1. The heat insulating material has a layer made of silicon oxide between the metal vapor-deposited sheet and the nonwoven fabric sheet.
The superconducting cable according to claim 2. In the multilayer heat insulating material, the thicknesses of the plurality of layers respectively constituted by the plurality of heat insulating materials are thicker in the order of being laminated from the superconducting cable core side toward the outer tube side ,
The superconducting cable according to any one of claims 1 to 3. The plurality of heat insulating materials have different thicknesses so that the interval between the metal vapor deposition sheets of the plurality of heat insulating materials stacked in the multilayer heat insulating material increases from the inner layer side to the outer layer side of the multilayer heat insulating material. Having the nonwoven fabric sheet,
The superconducting cable according to claim 2 or 3.

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