JP5505866B2 - Insulated tube and superconducting cable - Google Patents

Description

  The present invention relates to a heat insulating tube and a superconducting cable including the heat insulating tube. In particular, the present invention relates to a heat insulating pipe capable of reducing heat penetration and improving the heat insulating property of the heat insulating pipe, and a superconducting cable including the heat insulating pipe.

  In general, in a superconducting cable, the outer side of a single core cable core or a cable core formed by twisting a plurality of cables is covered with a heat insulating tube. For example, the heat insulating pipe described in Patent Document 1 is composed of a double pipe of a refrigerant pipe (inner pipe) and an outer pipe (outer pipe), and a radiation shield layer is wound around the outer circumference of the refrigerant pipe. A spacer is disposed between the shield layer and the outer tube. The spacer is formed in a pipe shape with a circular cross section, and is arranged by winding a single or a plurality of spirals between the shield layer and the outer tube.

JP 09-126389 A

  When a single spacer as described above is provided in a spiral shape, the contact area between the spacer and the outer periphery of the outer tube (outer tube) and the shield layer provided on the outer periphery of the refrigerant tube (inner tube) can be reduced. it can. Therefore, heat conduction can be kept low, and as a result, heat intrusion can be reduced, and it is considered that heat insulation can be maintained. However, with a single spacer, it is difficult to maintain a sufficient distance between the inner tube and the outer tube. This is because there are a wide range of locations where the spacers are not arranged in the circumferential direction of the inner tube. For this reason, the inner tube and the outer tube are likely to approach and come into contact with each other by the bending of the heat insulating tube at a location where the spacer is not disposed. As a result, the approaching portion easily receives heat from the outside, so that heat penetration cannot be suppressed and it is difficult to maintain heat insulation.

  On the other hand, when a plurality of the spacers as described above are provided in a spiral shape, it is difficult to generate a portion where the inner tube and the outer tube are easily brought into contact with each other due to the bending of the heat insulating tube. This is because a plurality of spacers are provided, so that the number of contact points between the spacer and the inner and outer tubes increases, and the interval between the inner and outer tubes can be easily maintained. However, when the number of contact points increases, the contact area between the spacer, the heat insulating layer, and the outer tube naturally increases. That is, since heat from the outside easily enters through the spacer, as a result, heat penetration increases and it is difficult to maintain heat insulation.

  The present invention was made in view of the above circumstances, and one of its purposes is to keep the distance between the inner and outer tubes while minimizing the contact area between the spacer and the other components of the heat insulating tube, Accordingly, an object of the present invention is to provide a heat insulating tube that can improve heat insulating properties.

  Another object of the present invention is to provide a heat insulating tube capable of reducing the constituent material of the spacer.

  Furthermore, the other object of this invention is to provide the superconducting cable which provides the said heat insulation pipe | tube.

  The present invention achieves the above object by devising the structure of the spacer to reduce the contact area of the spacer.

  The heat insulating pipe of the present invention includes an inner pipe, an outer pipe provided so as to cover the outer periphery of the inner pipe, a heat insulating material disposed between the inner and outer pipes, and a spacer that keeps a space between the inner and outer pipes. . The spacer includes a ring body that surrounds the inner pipe and is arranged in parallel in the longitudinal direction of the inner pipe, and a string-like body that maintains an interval between the ring bodies.

  According to said structure, as shown in the trial calculation example mentioned later, a contact area with structural members other than the spacer of a heat insulation pipe | tube can be made small by covering the outer periphery of an inner pipe | tube with a ring body. Therefore, the amount of heat penetration into the inner pipe or the amount of heat dissipated from the inner side of the inner pipe can be suppressed, and the heat insulating performance of the heat insulating pipe can be improved. Moreover, since the ring body surrounds the outer periphery of the inner tube, the interval between the inner and outer tubes can be kept constant at any location in the circumferential direction of the inner tube. Therefore, the generation | occurrence | production of the location which is easy to contact with an inner and outer pipe | tube does not arise, and heat insulation can be improved. Further, since the ring bodies are arranged in parallel in the longitudinal direction of the inner pipe, the distance between the inner and outer pipes can be maintained over the entire length in the longitudinal direction, and when viewed from the entire length of the heat insulating pipe, The constituent material of (spacer) can be reduced. And the space | interval of ring bodies can be maintained by providing a string-like body.

  As one form of this invention heat insulation pipe | tube, the said spacer further comprises the connection part which the said ring body and the said string-like body connect, and the said connection part is because the said string-like body is wound around the said ring body. It is mentioned that it is configured.

  According to said structure, by providing a connection part, positioning of a ring body and a string-like body and positioning of ring bodies are easy to be performed. The ring body and the string-like body can be easily connected by winding the string-like body around the ring body, and the positional displacement between the ring body and the string-like body is unlikely to occur. It becomes easy.

  As one form of this invention heat insulation pipe | tube, the said spacer further comprises the connection part which the said ring body and the said string-like body connect, and the said connection part is because the said string-like body is tied with the said ring body. It is mentioned that it is configured.

  According to said structure, a ring body and a string-like body can be firmly connected by connecting a string-like body to a ring body, and it becomes easier to maintain the space | interval of ring bodies.

  As one form of this invention heat insulation pipe | tube, the said spacer is further provided with the connection part which the said ring body and the said string-like body connect, and the said connection part is because the said string-like body penetrates the said ring body. It is mentioned that it is configured.

  According to said structure, a ring body and a string-like body can connect both easily by letting a string-like body penetrate the ring body.

  As one form of this invention heat insulation pipe | tube, it is mentioned that the said ring body is formed with the fluororesin.

  According to the above configuration, since the fluororesin has a low gas release rate, when the space between the inner and outer tubes is evacuated, the degree of vacuum between the inner and outer tubes can be maintained. Therefore, high heat insulation can be maintained. Moreover, even if the spacer is affected by heat penetration from the outside through the outer tube, the heat conductivity of the fluororesin itself is low, so it is easy to suppress a decrease in the heat insulating property of the heat insulating tube. Further, since the fluororesin is a low friction material, the ring body or the heat insulating material is hardly damaged or deteriorated due to sliding with the heat insulating material disposed between the inner tube, the outer tube, or the inner and outer tubes.

  As one form of this invention heat insulation pipe | tube, it is mentioned that the said string-like body is formed from 1 type selected from polyester, polyamide, polyethylene, a polypropylene, a polyurethane, polyphenylene sulfide, and a fluororesin.

  According to said structure, since it has sufficient mechanical characteristics for connecting the said ring bodies, a string-shaped body and ring bodies can be connected, without a string-shaped body being cut | disconnected.

  The superconducting cable of the present invention includes the above-described heat insulating tube of the present invention and a cable core having a superconducting conductor layer. And the said cable core is accommodated in the said heat insulation layer.

  According to said structure, since the heat insulation pipe | tube with high heat insulation is provided, the energy required for cooling of a cable core can be reduced.

  The heat insulating pipe of the present invention improves the heat insulating property of the heat insulating pipe because the space between the inner pipe and the outer pipe can be stably maintained while minimizing the contact area between the spacer and the other components of the heat insulating pipe. can do. Further, the constituent material of the spacer can be reduced.

  Since the superconducting cable of the present invention includes the above-described heat insulating pipe having high heat insulating properties, energy required for cooling the cable core can be reduced.

1 is a schematic perspective view showing a heat insulating tube according to Embodiment 1. FIG. 6 is a schematic perspective view showing a superconducting cable according to Embodiment 2. FIG.

  Embodiments of the present invention will be described below. Here, first, a heat insulation pipe | tube is demonstrated based on FIG. 1, and the superconducting cable provided with the heat insulation pipe | tube is demonstrated based on FIG. In the drawings, the same reference numerals indicate the same or corresponding parts.

<< Insulated pipe >>
<Embodiment 1>
As shown in FIG. 1, the heat insulating tube 1 according to the first embodiment includes an inner tube 10 i, an outer tube 10 o, a heat insulating material 11, and a spacer 12. The heat insulating material 11 and the spacer 12 are disposed between the inner tube 10i and the outer tube 10o. Details of each configuration are shown below.

[Inner tube, outer tube]
The inner tube 10i and the outer tube 10o are long tubes that form a heat insulating space between the two tubes and thermally isolate the fluid flowing through the inner tube 10i from the outside of the outer tube 10o. In this example, both the inner tube 10i and the outer tube 10o are stainless corrugated tubes in which spiral irregularities are formed in the longitudinal direction. In the case of a corrugated tube having spiral irregularities, when a spacer 12 to be described later is disposed in a space between the inner and outer tubes 10i, 10o, an exhaust path for evacuating this space can be easily formed. The corrugated tube may have bellows-shaped irregularities. The fluid flowing in the inner pipe 10i has a wide temperature range from a very low temperature to a high temperature. Examples thereof include liquid nitrogen, liquid hydrogen, liquid oxygen, liquid helium, liquefied natural gas, hydrogen gas, helium gas, steam, hot water, and the like.

  As for the shapes of the inner tube 10i and the outer tube 10o, in addition to the corrugated tube, when there is no need for bending or when the heat insulating tube 1 is used at a short distance, a straight tube having no irregularities in the longitudinal direction can be used for a straight section. .

  As the material of the inner tube 10i and the outer tube 10o, metals such as aluminum having flexibility and strength can be used in addition to stainless steel.

  The thickness of the inner tube 10i and the outer tube 10o is set to a thickness that can withstand the internal pressure of the fluid flowing through the inner tube 10i. However, the inner tube 10i and the outer tube 10o may have different thicknesses. For example, since the fluid pressure acts directly on the inner tube 10i, the inner tube 10i is made thicker than the outer tube 10o, and the outer tube 10o is reduced in weight while ensuring the pressure resistance of the inner tube 10i. It is done.

[Insulation]
Between the inner pipe 10i and the outer pipe 10o, a heat insulating material 11 is provided to improve the heat insulating property of the heat insulating tube 1 by blocking the radiation heat from the inside of the heat insulating tube 1 and the penetration of the radiant heat from the outside. Is provided. As a specific example of the heat insulating material 11, a so-called super insulation (trade name) of a laminated material obtained by laminating a belt-shaped material in which aluminum is vapor-deposited on one surface or both surfaces of a belt-shaped resin film and a mesh structure material made of synthetic fiber. Can be mentioned.

  As an arrangement form of the heat insulating material 11, it is preferable to wind around the outer periphery of the inner tube 10 i so as to cover the entire surface. In particular, the heat insulating material 11 may be wound along the uneven structure (spiral) of the inner tube 10i. By winding the heat insulating material 11 along the spiral, it is easy to wind densely around the entire outer periphery of the inner tube 10i. In addition, as a means to arrange | position the said heat insulating material 11, you may provide along the longitudinal direction of the inner tube | pipe 10i.

  Further, in this example, the position where the heat insulating material 11 is disposed is disposed immediately above the inner tube 10i, but may be disposed between the inner tube 10i and the outer tube 10o. I do not care. For example, a spacer 12 to be described later is disposed immediately above the inner tube 10i, and the heat insulating material 11 is disposed between the spacer 12 and the outer tube 10o, or between the inner peripheral heat insulating material and the outer peripheral heat insulating material. The spacers 12 may be arranged so as to be sandwiched.

[Spacer]
Between the inner pipe 10i and the outer pipe 10o (between the heat insulating material 11 and the outer pipe 10o in this example), the inner pipe 10i and the outer pipe 10o, specifically, the heat insulating material 11 (the inner pipe 10i) and the outer pipe A spacer 12 is disposed to maintain a distance from the tube 10o (heat insulating material 11). The spacer 12 surrounds the outer periphery of the heat insulating material 11 (inner tube 10i), and a plurality of ring bodies 12r arranged in parallel in the axial direction (longitudinal direction) of the heat insulating tube 1 and the interval between the ring bodies 12r are maintained. It is comprised from the string-like body 12b. Furthermore, the spacer 12 includes a connecting portion 12c that connects the ring body 12r and the string-like body 12b. Each configuration will be described below.

(Ring body)
The ring body 12r is a member that plays a role of maintaining a distance between the inner tube 10i and the outer tube 10o substantially. In this example, the ring body 12r is constituted by a linear body having a circular cross-sectional shape, and the cross-sectional area and the cross-sectional shape of the linear body are uniform in the longitudinal direction. By constituting the ring body 12r with a linear body having a circular cross section, the contact with the heat insulating material 11 (inner tube 10i) and the outer tube 10o (heat insulating material 11) can be made into line contact, and the contact area is reduced. be able to.

  The cross-sectional shape of the linear body constituting the ring body 12r may be a non-circular shape such as a polygonal shape or an annular shape. If it is a linear body with a polygonal cross section, it can be in line contact with other members of the heat insulating tube 1 at the ridgeline corresponding to the apex thereof. If the linear body has an annular cross section, the linear body can be a hollow body, and the cross-sectional area can be further reduced if the outer shape of the linear body constituting the ring body 12r is constant. As a result, heat conduction inside and outside the heat insulating tube 1 can be reduced more effectively.

  As the form along the circumferential direction of the ring body 12r, there are a configuration in which there is no seam in the middle of the linear body and a configuration in which there is a seam. The former can be obtained by forming a seamless ring body 12r by resin molding, or by forming a cylindrical material in advance and cutting the cylindrical material at small intervals. The latter can be obtained by bending the linear body and joining the ends with a tape or an adhesive to form a ring.

  The thickness of the ring body 12r (difference between the inner diameter and the outer diameter of the ring body 12r) and the width (width of the linear body in the axial direction of the ring body) are respectively set to a desired interval between the inner tube 10i and the outer tube 10o. It is preferable to have a degree that can be maintained at an interval. Specifically, the thickness is preferably 1 to 5 mm, and the width is preferably 1 to 5 mm. If it is said range, since the space | interval of the inner tube 10i and the outer tube 10o can be maintained, making the contact area of the inner tube 10i and the outer tube 10o small, heat penetration can be reduced, and heat insulation can be achieved. It can be made excellent in properties.

  The material of the ring body 12r is preferably formed of a material such as a fluororesin that has a low gas release rate and a low thermal conductivity. For example, in this example, a material formed from polytetrafluoroethylene (PTFE) is used, but by using a material having a low gas release rate as described above, the inner and outer tubes 10i and 10o are evacuated to be insulated. When enhancing the properties, a high degree of vacuum can be maintained. That is, by maintaining a high degree of vacuum, the heat insulating tube 1 can be maintained in a high heat insulating state. In addition to the above fluororesin, fiber reinforced plastic (FRP) such as glass fiber reinforced plastic (GFRP) can also be used.

  And the place which provides this ring body 12r is the position which can maintain the space | interval of the inner / outer pipe | tube 10i, 10o over the full length of the heat insulation pipe | tube 1 irrespective of the presence or absence of the bending of the heat insulation pipe | tube 1 (insulation material). 11) must be arranged so as to surround the outer periphery. For this purpose, the interval between the ring bodies 12r (ring pitch) and the number of ring bodies 12r may be appropriately selected.

(String)
The string-like body 12b is a member that plays a role of connecting the ring bodies 12r to a state held at a predetermined interval. In this example, the string-like body 12b is constituted by a fine polyester wire. If it is a polyester thin wire, the connection part 12c mentioned later can be formed easily, and it will be hard to damage and cut | disconnect from each step of manufacture of the heat insulation pipe | tube 1 to use.

  As for the thickness of the string-like body 12b, the string-like body 12b itself preferably has an outer diameter that does not cause heat intrusion. In particular, the thickness is preferably thinner than the linear body constituting the ring body 12r. Specifically, it is preferable that the diameter is 0.5 mm or less or about 5 to 15% of the thickness of the linear body constituting the ring body 12r.

  The material of the string-like body 12b is flexible enough to be wound around or tied to the ring body 12r, and strong enough not to break even if connected to the ring body 12r while keeping the distance between the ring bodies 12r. It is necessary to have. In addition to polyester, polyamide (PA), polyethylene (PE), polyurethane (PU), polypropylene (PP), polyphenylene sulfide (PPS), fluororesin, glass fiber as other constituent materials of the string-like body 12b Examples thereof include reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP).

  The number of string-like bodies 12b may be at least one, and it is preferable to use a plurality. When a plurality of string-like bodies 12b are used, the string-like body 12b can also have a function of holding the ring bodies 12r coaxially.

  The string-like body 12b is preferably arranged along the longitudinal direction of the inner tube 10i. In this example, a total of four string-like bodies 12b vertically attached to the outside of the inner tube 10i are arranged at equal intervals in the circumferential direction of the inner tube 10i. And the some location in the middle of each string-like body 12b is connected with each ring body 12r by the connection part 12c mentioned later. When there are a plurality of string-like bodies 12b, they may be arranged in parallel at equal intervals in the circumferential direction of the inner tube 10i (heat insulating material 11). For example, in the case of two, the positions corresponding to the vertices of regular polygons when the cross section of the heat insulating tube 1 is viewed in the opposite position on the outer periphery of the inner tube 10i when the cross section of the heat insulating tube 1 is viewed. It is good to arrange in.

(Connecting part)
In this example, the connecting portion 12c that connects the ring body 12r and the string-like body 12b is configured by winding the middle of the string-like body 12b around the ring body 12r. This winding is a simple means for constituting the connecting portion 12c. The ring body 12r may be cut to facilitate winding of the string-like body 12b. For example, an annular groove that extends to the outer periphery of the linear body that constitutes the ring body 12r to the extent that the diameter of the string-shaped body 12b fits can be mentioned. By winding the string-like body 12b around this notch, the positional relationship between the ring body 12r and the string-like body 12b becomes difficult to shift. When winding the string-like body 12b, the string-like body 12b may be wound only for one round or more.

  As another structure of the said connection part 12c, connecting the middle of the string-like body 12b to the ring body 12r, or making the ring-shaped body 12b penetrate the string-like body 12b is mentioned. The connection part 12c by this connection can be comprised by the various connection method of the string-like body 12b, and can hold | maintain the space | interval of the ring bodies 12r more reliably. Further, the connecting portion 12c by penetration can be configured by, for example, piercing the ring body 12r with a needle attached to the end of the string-like body 12b and simultaneously performing drilling and penetration. And when penetrating and comprising the connection part 12c, it is preferable to provide the string body 12b with respect to at least the ring body 12r positioned at both ends of the spacer 12. The retainer can be easily formed by tying the string-like body 12b or attaching a stopper to the string-like body 12b to provide a large-diameter portion that does not pass through the through-hole in the middle of the string-like body 12b. it can. In addition, in the ring body 12r other than both ends of the spacer 12, by providing the string-shaped body 12b before and after the through-holes, the interval between the ring bodies 12r can be more reliably maintained.

  Furthermore, each structure of the three connection parts 12c of the said winding, connection, and penetration may be mixed and comprised by the appropriate combination with respect to the some connection part 12c. In this case, for example, the ring body 12r and the string-like body 12b at both ends are connected, and the ring body 12r and the string-like body 12b other than both ends are wound or penetrated. And as another structure of the connection part 12c, connecting both the ring body 12r and the string-like body 12b using an adhesive tape or an adhesive agent is also mentioned.

[Method for forming and arranging spacers]
As a method of disposing the spacer 12 between the inner pipe 10i (heat insulating material 11) and the outer pipe 10o, when the ring body 12r is formed seamlessly, first, the pair of ring bodies 12r are separated by a predetermined distance. And is connected with a string-like body 12b. Next, another ring body 12r is also connected by the string-like body 12b with a predetermined interval from one of the pair of ring bodies 12r. Thereafter, the ring bodies 12r are sequentially connected in the same manner, and the spacers 12 are formed in such a manner that the intervals between the ring bodies 12r are maintained at a desired distance. Then, each ring body 12r is fitted from one end side of the inner tube 10i (heat insulating material 11) and sequentially shifted to the other end side so that the ring bodies 12r are arranged in parallel at a predetermined interval in the longitudinal direction of the inner tube 10i. Thus, the spacer 12 is disposed on the outer periphery of the inner tube 10i.

  Moreover, when the ring body 12r is formed by bending linear linear bodies and joining the ends, the linear bodies are first arranged in parallel so that they are parallel to each other. In that case, it arrange | positions so that the space | interval of linear bodies may become a desired space | interval. Next, a predetermined number of string-like bodies are arranged so as to be orthogonal to the linear bodies, and are connected to the linear bodies. At this time, the connecting portion 12c may be formed as described above. Thereby, a net-like body is formed by the connected linear body and the string-like body. Subsequently, the linear body portion of the mesh body is wound around the outer periphery of the inner tube 10i (heat insulating material 11). Then, the ends of the linear bodies may be joined with a tape, an adhesive, or the like, so that the formation of the ring body 12r and the arrangement of the spacers 12 may be performed simultaneously.

(Other)
As described above, after the heat insulating material 11 and the spacer 12 are disposed between the inner tube 10i and the outer tube 10o, the inner tube 10i and the outer tube 10o are evacuated and kept in a vacuum state. By making a vacuum between the inner tube 10i and the outer tube 10o, the heat insulating property of the heat insulating tube 1 is further enhanced.

[Function and effect]
According to the heat insulation pipe concerning the embodiment mentioned above, the following effects are produced.

  (1) Since the cross section of the ring body, which is a main component of the spacer, is circular, the spacer and other components of the heat insulating tube can be in line contact, and therefore the contact area can be reduced. As a result, heat intrusion from the outside can be reduced through the spacer, and the heat insulating property of the heat insulating tube can be improved.

  (2) Since a plurality of ring bodies are juxtaposed in the longitudinal direction of the inner tube, the distance between the inner tube and the outer tube can be maintained over the entire length of the heat insulating tube. And when it sees with the full length of a heat insulation pipe | tube, the constituent material of a ring body (spacer) can be reduced.

  (3) Since the ring bodies are connected by a string-like body, the interval between the ring bodies can be maintained.

<< Superconducting cable >>
<Embodiment 2>
Next, an example of the overall configuration of the superconducting cable 2 according to the second embodiment will be described with reference to FIG. A superconducting cable 2 shown in FIG. 2 includes a heat insulating tube 1 and a cable core 20. The heat insulating tube 1 is the heat insulating tube 1 according to the first embodiment. The cable core 20 is housed in the heat insulating tube 1. In this example, a three-core superconducting cable that collectively stores three cores in the heat insulating tube 1 is shown. Hereinafter, the configuration of the superconducting cable 2 will be described. In addition, about the structure of the heat insulation pipe | tube 1, description is abbreviate | omitted.

[Cable core]
Each cable core 20 includes a former 21, a superconducting conductor layer 22, an electrical insulating layer 23, and a superconducting shield layer 24 in order from the center. Among these layers, the superconductor material 30 is used for the superconducting conductor layer 22 and the superconducting shield layer 24.

(Former (core material))
The former 21 can use a solid body or hollow pipe made of a normal conducting material such as copper or aluminum, or a stranded wire obtained by twisting a plurality of strands. For example, when a hollow body is used, the inside thereof can be used as a refrigerant flow path. In this example, the former 21 is composed of a stranded wire of copper strands.

(Superconducting conductor layer)
The superconducting conductor layer 22 has a single-layer or multi-layer structure formed by spirally winding the superconducting wire 30 around the outer periphery of the former 21, and an interlayer insulating layer is provided between the layers by winding an insulating material such as kraft paper. ing. As shown in FIG. 2, the superconducting wire 30 has a configuration in which a plurality of superconducting filaments are spirally twisted and incorporated in a metal matrix. Here, a superconducting wire 30 in which a plurality of superconducting filaments made of Bi2223 oxide superconductor are covered with a silver sheath and a silver alloy sheath is used.

(Electrical insulation layer)
The electrical insulating layer 23 is formed by winding an insulating paper tape such as kraft paper, a semi-synthetic insulating tape obtained by combining kraft paper and a plastic film, for example, a tape-like insulating material such as PPLP (registered trademark) manufactured by Sumitomo Electric Industries, Ltd. The rotated configuration can be mentioned. Further, an inner semiconductive layer (not shown) is provided inside the electrical insulating layer 23, and an outer semiconductive layer (not shown) is provided outside.

(Superconducting shield layer)
The superconducting shield layer 24 has a single-layer or multi-layer structure formed by spirally winding a multi-core superconducting wire 30 (the above-described Bi2223-based tape wire) similar to the superconducting conductor layer 22 around the outer periphery of the electrical insulating layer 23. The basic configuration is the same as that of the superconducting conductor layer 22. The superconducting shield layer 24 has an action of canceling out the generation of a magnetic field to the outside of the cable by inducing a current in the reverse direction with approximately the same magnitude as the alternating current when the superconducting conductor layer 22 is energized. . In the superconducting cable 2 shown in this example, in order to protect the superconducting wire 30 on the outer periphery of the superconducting shield layer 24, the normal conducting shield layer 25 made of a normal conducting material such as copper, and the outer periphery of the normal conducting shield layer 25. A protective layer 26 made of craft paper is provided. In the case of a DC superconducting cable, if the superconducting conductor layer 22 is a current forward path (current return path), the superconducting shield layer 24 can be used as an external superconducting layer serving as a current return path (current forward path).

[Other configurations]
The superconducting cable 2 described above maintains the superconducting conductor layer 22 and the superconducting shield layer 24 in a superconducting state by flowing a coolant through the inner pipe 10i during operation. As this refrigerant, liquid nitrogen is typical, and in addition, liquid hydrogen, liquid helium, or the like can be used. The space between the inner tube 10i and the outer tube 10o is evacuated. By making a vacuum between the inner tube 10i and the outer tube 10o, the heat insulating property of the heat insulating tube 1 is further enhanced. Moreover, the corrosion resistance is improved by providing the anti-corrosion layer 28 which consists of polyvinyl chloride in the outer periphery of the heat insulation pipe | tube 1 (outer pipe | tube 10o).

[Function and effect]
According to the superconducting cable described above, since the heat insulating pipe having high heat insulating properties is provided, the energy required for cooling the cable core can be reduced.

<Example of trial calculation>
As a trial calculation example, heat intrusion in the heat insulating pipe (example) using the spacer according to the first embodiment described above and heat intrusion in the heat insulating pipe (comparative example) using a spacer in which a plurality of linear bodies are arranged in a spiral shape. And compared. Specifically, the lengths of the ring body and the linear body when spacers are arranged outside the inner pipe were respectively calculated and compared. At that time, the contact area between the inner tube and the spacer was considered to depend only on the length of the spacer. In addition, the string-like body used in the embodiment is merely a function of connecting the ring bodies to each other, and is substantially free from heat intrusion due to maintaining the interval between the inner and outer pipes and contacting with other constituent members of the heat insulating pipe other than the spacer. Since it is not involved, it is not included in the comparison target with the comparative example.

  Three types of tubes having spacers with an outer diameter of 150 mm and lengths of 300, 500, and 1000 mm were prepared. In Comparative Examples 1 to 3, the winding pitch (spiral pitch) when winding the linear body around each of the tubes was set to 1 pitch of the length of each tube. And all eight linear bodies were arranged in parallel at equal intervals in the circumferential direction of the tube at the same spiral pitch. On the other hand, in Examples 1 to 3, the ring pitch (interval between adjacent ring bodies) was selected so that the function of the spacer was equivalent to the spacer of the comparative example. The ring pitch was a value obtained by dividing the helical pitch by the number of spacers wound. That is, when the length of the tube is 300 mm, the pitch of the ring body is 300/8 and 37.5 mm, and similarly, the pitch when 500 mm is 62.5 mm and the pitch when 1000 mm is 125 mm. A total of eight ring bodies were arranged in parallel in the longitudinal direction of the pipe at each pitch. Thereafter, the total length of the ring body was calculated in the example, and the total length of the eight linear bodies was calculated in the comparative example. The results are shown in Table 1.

[result]
As shown in Table 1, in Comparative Examples 1 to 3 in which the linear bodies are arranged in a spiral shape, the total length of the linear bodies is longer than the total length of the ring bodies in Examples 1 to 3. That is, since the contact area between the spacer and the constituent member of the heat insulating pipe other than the spacer depends on the total length, the contact areas can be reduced in the first to third embodiments using a ring body, Intrusion is reduced. In addition, the fact that the total length is short can also reduce the constituent material of the spacer.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, the roles of the spacer ring and string may be reversed from those in the first embodiment.

  In that case, for example, it is constituted by a ring body made of a thin line and a string-like body made of a linear body having a circular cross section. Along with this, the string-like body substantially plays a role of maintaining the distance between the inner tube and the outer tube, and the ring body plays a role of keeping the distance between the string-like bodies. At this time, the dimensions of the ring body and the string-like body are also reversed. Specifically, the thickness of the string-like body is preferably 1 to 5 mm and the width is preferably 1 to 5 mm. The ring body has a diameter of 0.5 mm or less or the thickness of the linear body constituting the string-like body. And preferably having a thickness of about 5 to 15%. Then, eight string-like bodies are arranged at equal intervals (heat insulation) in the circumferential direction of the inner pipe (heat insulating material) so as to keep the distance between the inner pipe and the outer pipe by the string-like body provided along the longitudinal direction of the inner pipe. When the tube is viewed in cross section, it is arranged at a position corresponding to the apex of a regular octagon. Moreover, a connection part is comprised by winding the thin wire | line which comprises a ring body around a string-like body.

  The heat insulation pipe of the present invention can be suitably used for a transport pipe and a storage pipe for various fluids for which heat insulation from the outside is desired, and other components of superconducting cables. Moreover, the superconducting cable of the present invention can be suitably used as a constituent member of a power transmission line.

DESCRIPTION OF SYMBOLS 1 Heat insulation pipe | tube 2 Superconducting cable 10i Inner pipe | tube 10o Outer pipe | tube 11 Heat insulating material 12 Spacer 12r Ring body 12b String-like body 12c Connecting part 20 Cable core 21 Former 22 Superconducting conductor layer 23 Electric insulation layer 24 Superconducting shield layer 25 Normal conducting shield layer 26 Protective layer 28 Anticorrosive layer 30 Superconducting wire

Claims (7)

An insulating tube comprising an inner tube, an outer tube provided so as to cover the outer periphery of the inner tube, a heat insulating material disposed between the inner and outer tubes, and a spacer for maintaining a space between the inner and outer tubes. And
The spacer is
A plurality of ring bodies surrounding the inner tube and juxtaposed in the longitudinal direction of the inner tube;
A string-like body that keeps an interval between the ring bodies;
Insulated pipe characterized by comprising. Further, the spacer includes a connecting portion that connects the ring body and the string-like body,
The heat insulation pipe according to claim 1, wherein the connecting portion is configured by winding the string-like body around the ring body. Further, the spacer includes a connecting portion that connects the ring body and the string-like body,
The heat insulation pipe according to claim 1, wherein the connecting portion is configured by binding the string-like body to the ring body. Further, the spacer includes a connecting portion that connects the ring body and the string-like body,
The heat insulation pipe according to claim 1, wherein the connecting portion is configured by the string member penetrating the ring body.   The said ring body is formed with the fluororesin, The heat insulation pipe | tube of any one of Claims 1-4 characterized by the above-mentioned.   The said string-like body is formed from 1 type selected from polyester, polyamide, polyethylene, a polypropylene, a polyurethane, polyphenylene sulfide, and a fluororesin, The any one of Claims 1-5 characterized by the above-mentioned. The heat insulation pipe | tube as described in a term. The heat insulation pipe according to any one of claims 1 to 6,
A superconducting cable comprising a cable core housed in the heat insulating tube and having a superconducting conductor layer.

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