JP5003863B2 - Superconducting cable manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a superconducting cable comprising a cable core having a superconducting conductor layer and a heat insulating tube for housing the core. In particular, the present invention relates to a method of manufacturing a superconducting cable that can reduce moisture contained in an electrical insulating layer provided on the outer periphery of a superconducting conductor layer or a heat insulating material layer provided in a heat insulating tube.

  In recent years, superconducting cables have been studied as power cables. For example, a superconducting cable having the configuration shown in FIG. 3 has been proposed. The superconducting cable 100 has a configuration in which three cores 110 are housed in a heat insulating tube 120. Each core 110 is composed of a former 111, a superconducting conductor layer 112, an electric insulating layer 113, and an external superconducting layer 114 in order from the center. A protective layer 115; The former 111 is formed by twisting strands made of a normal conducting material such as copper, and a superconducting conductor layer 112 is formed on the former 111 by winding a superconducting wire spirally in multiple layers. A typical example of the superconducting wire is a tape-like one in which a plurality of filaments made of an oxide superconducting material are arranged in a silver sheath. An electric insulating layer 113 is formed by winding insulating paper such as kraft paper or semi-synthetic insulating paper such as PPLP (registered trademark) on the superconducting conductor layer 112, and the superconducting wire as described above is formed on the insulating layer 13. Is wound to form the external superconducting layer 114. Further, a protective layer 115 is formed by winding an insulating paper such as kraft paper on the external superconducting layer 114, and the cable core 110 is manufactured.

  The heat insulating tube 120 has a double structure composed of an inner tube 121 and an outer tube 122, and both the tubes 121 and 122 use a flat tube having a smooth surface or a corrugated tube having excellent flexibility (corrugated tube). (See Patent Document 1). A heat insulating material (not shown) is wound around the outer periphery of the inner tube 121, and a heat insulating material layer is provided between the inner tube 121 and the outer tube 122. A typical example of the heat insulating material is super insulation (trade name) in which aluminum is vapor-deposited on the surface of a polyester film. A vacuum is drawn between the inner tube 121 and the outer tube 122. An anticorrosion layer 123 is provided outside the heat insulating tube 120. The superconducting cable 100 including the cable core 110 and the heat insulating tube 120 is configured such that during operation, a refrigerant such as liquid nitrogen is supplied to a space formed between the inner peripheral surface of the inner tube 121 and the outer peripheral surface of the core 110. The superconducting conductor layer 112 and the external superconducting layer 114 are cooled by filling and circulating. At this time, the electrical insulating layer 13 is in a state of being impregnated with a refrigerant.

  In order to obtain a state in which the cable core is housed in the heat insulating tube, it is possible to form a heat insulating tube on the outer periphery of the core. In Patent Document 2, a stainless steel plate is placed on the outer periphery of the cable core, the plate is bent so as to cover the core, the edges of the plate are attached together, a seam is welded with a welder, etc., and the outer periphery of the core is flattened. It is described that an inner tube made of a tube is formed, or that the inner tube is introduced into a corrugator after welding to form a corrugated tube (see Patent Document 2 FIG. 4). Patent Document 2 describes that aluminum is extruded on the outer periphery of a cable core to form an inner tube (see Patent Document 2 FIG. 6). After the heat insulating material is wound around the outer periphery of these inner tubes, the outer tube is provided on the outer periphery of the heat insulating material layer in the same manner as the inner tube.

JP 2001-4076 JP 2001-67950 A

  The inner and outer tubes are usually formed in the atmosphere. Therefore, during the formation of the inner and outer pipes, the electrical insulation layer provided in the cable core and the heat insulation layer provided on the outer periphery of the inner pipe absorb moisture in the air, and the electric insulation layer and the heat insulation layer are excessive. There is a problem that it may contain moisture.

  Insulating paper often used as a material for forming an electrical insulating layer and insulating materials including insulating paper are likely to absorb moisture, and absorb moisture when exposed to the atmosphere. Therefore, even if an insulating material that has been dried in advance is used, the electrical insulating layer absorbs moisture in the atmosphere by forming the electrical insulating layer and the inner tube in the atmosphere. Further, when the inner tube is provided on the outer periphery of the core, the moisture contained in the electrical insulating layer is difficult to escape to the outside. When the electric insulation layer contains excessive moisture, when the refrigerant is filled in the inner tube in this state, the moisture in the insulation layer is cooled and solidified by the refrigerant, and the solidified product causes the refrigerant transportation path. There is a risk of blocking. Here, in the power supply line using the superconducting cable, a cooling system equipped with a tank, a refrigerator, etc. is arranged, and the refrigerant adjusted to an appropriate temperature and transport pressure by the cooling system is supplied to the cable, and the intrusion heat Refrigerant circulation supply has been proposed in which a refrigerant whose temperature has been raised due to friction during transportation or the like is discharged from a cable and returned to a cooling system. A refrigerant transport path is constructed by this cooling system, the inner pipe of the superconducting cable, and the refrigerant transport pipe connecting them. There may be a portion with a relatively small cross-sectional area in the refrigerant transportation path, and if the moisture (ice) solidified with the circulation of the refrigerant is transported to such a place, the refrigerant transportation path may be clogged. There is. When the refrigerant transport path is blocked, a refrigerant having an appropriate temperature cannot be supplied to the superconducting cable, and the core cannot be appropriately cooled. For this reason, the superconducting conductor layer and the external superconducting layer cannot be maintained in a superconducting state, and in the worst case, the operation of the line must be stopped.

  On the other hand, the heat insulating material that is a material for forming the heat insulating material layer also absorbs moisture when exposed to the atmosphere in the same manner as the above insulating material. Therefore, the heat insulating material layer may absorb moisture in the air by forming the heat insulating material layer and the outer tube in the air. And when water | moisture content exists in a heat insulating material layer, when this water | moisture content vaporizes, there exists a possibility of reducing the vacuum degree of a heat insulation pipe | tube. After the outer tube is formed on the outer periphery of the heat insulating material layer, the moisture in the heat insulating material layer can be substantially removed by evacuating the inner tube and the outer tube. However, if the moisture content of the heat insulating material layer is large, it takes a long time for the evacuation. The evacuation between the inner tube and the outer tube is performed, for example, by heating the entire cable and sucking from one end side of the cable. For this reason, long superconducting cables of several hundred meters to several kilometers require a long time for evacuation in the first place, but if the moisture content in the heat insulating material layer is large, more moisture is vaporized and exhausted. Time is required. If the time is shortened, moisture remains, which may vaporize and reduce the degree of vacuum. Since the heat insulating tube is required to maintain an ultra-high vacuum state for a long period of time, it is necessary to sufficiently discharge moisture that causes a decrease in the degree of vacuum. As a method for shortening the time, it is conceivable to increase the heating temperature. However, some cable core forming members have a low heat-resistant temperature, and when heating is performed with the core housed in the inner tube, there is a limit to the increase in heating temperature in view of preventing damage to the core.

  Then, the main objective of this invention is to provide the manufacturing method of the superconducting cable which can manufacture the superconducting cable with less moisture content of an electric insulation layer or a heat insulating material layer.

  The present invention reduces the moisture content in the electrical insulating layer and the heat insulating material layer by making a vacuum state before forming the inner tube and the outer tube, and subsequently maintains the vacuum state while maintaining the vacuum state. The above object is achieved by forming

The superconducting cable manufacturing method of the present invention is a superconducting device comprising a cable core having an electrical insulating layer on the outer periphery of a superconducting conductor layer, a double structure comprising an inner tube and an outer tube, and a heat insulating tube for housing the core. The cable is manufactured, and includes the following steps 1 to 3.
1 Process of forming a cable core by winding an insulating material using insulating paper around the superconducting conductor layer to form an electrical insulation layer
2 The process of heating the cable core in a vacuum to reduce the moisture content in the electrical insulation layer
3 Forming the inner tube on the outer periphery of the cable core while maintaining the vacuum state of 2 above

Also, the method for manufacturing a superconducting cable according to the present invention manufactures a superconducting cable having a cable core having a superconducting conductor layer, a double structure comprising an inner tube and an outer tube, and a heat insulating tube for housing the core. It includes the following steps I and II.
I In the vacuum state, the process of reducing the moisture content in the heat insulating material layer by winding the heat insulating material around the outer periphery of the inner tube to form the heat insulating material layer
II Step of forming an outer tube on the outer periphery of the heat insulating material layer while maintaining the vacuum state of I above

Furthermore, the manufacturing method of the superconducting cable of the present invention includes both the steps relating to the moisture reduction of the electrical insulating layer and the formation of the inner tube, and the steps relating to the moisture reduction of the heat insulating material layer and the formation of the outer tube. Specifically, the superconducting cable manufacturing method of the present invention has a double structure consisting of a cable core having an electrical insulating layer on the outer periphery of a superconducting conductor layer, an inner tube and an outer tube, and a heat insulating tube for housing the core. A superconducting cable comprising the following steps 1-5.
1 Process of forming a cable core by winding an insulating material using insulating paper around the superconducting conductor layer to form an electrical insulation layer
2 The process of heating the cable core and reducing the moisture content in the electrical insulation layer in the first vacuum state
3 Forming the inner tube on the outer periphery of the cable core while maintaining the vacuum state of 2 above
4 In the second vacuum state, a process of reducing the moisture content in the heat insulating material layer by winding the heat insulating material around the outer periphery of the inner tube to form the heat insulating material layer
5 Step of forming an outer tube on the outer periphery of the heat insulating material layer while maintaining the vacuum state of 4 above

Hereinafter, the present invention will be described in more detail.
The present invention manufactures a superconducting cable comprising a cable core having a superconducting conductor layer and a heat insulating tube for housing the core. Such a superconducting cable is basically formed by forming a cable core and then forming a heat insulating tube on its outer periphery, or forming a cable core and a heat insulating tube separately, and then inserting the core into the heat insulating tube. To manufacture. After the cable core is housed in the heat insulating tube, the heat insulating tube is evacuated. Usually, a superconducting cable is laid in a state where the heat insulating pipe is evacuated to construct a power supply line, a refrigerant is introduced into the heat insulating pipe, and the line is operated in a state where the refrigerant is circulated.

  As a basic configuration of the cable core, a configuration having a former, a superconducting conductor layer, and an electrical insulating layer in order from the center can be given. An external superconducting layer made of a superconducting material in the same manner as the superconducting conductor layer on the outer periphery of the electric insulating layer, a structure having a protective layer on the outer periphery, and further between the superconducting conductor layer and the electric insulating layer, It can be set as the structure which has a semiconductive layer between these.

  The former is formed in a solid or hollow shape with a normal conductive material, for example, a conductive metal material such as copper or aluminum. More specifically, for example, a plurality of coated copper wires having an insulating layer such as enamel are twisted and formed. The superconducting conductor layer is formed, for example, by winding a wire made of an oxide superconducting material such as a superconducting material, typically a Bi2223 series superconducting material, around the former in a single layer or multiple layers. When the superconducting conductor layer is a multilayer, an interlayer insulating layer may be provided. The interlayer insulating layer is provided, for example, by winding insulating paper such as kraft paper. An electrical insulating layer is formed on the outer periphery of the superconducting conductor layer. As the insulating material for forming the electrical insulating layer, plastic or the like is conceivable, but an insulating material typified by kraft paper that is easily impregnated with a refrigerant is preferable. Specifically, insulating paper such as kraft paper, semi-synthetic insulating paper made of insulating paper and plastic film, and the like can be given. As the semi-synthetic insulating paper, for example, PPLP (registered trademark) obtained by laminating a polypropylene film on kraft paper can be used. Since the insulating material using these insulating papers easily absorbs moisture when exposed to the atmosphere, it is preferable to reduce the moisture content by drying before forming the electrical insulating layer. Examples of the drying method include spraying dry air on the insulating material, heating the insulating material, and putting the insulating material in a container to perform evacuation. The electrical insulating layer is formed by winding such an insulating material around the outer periphery of the superconducting conductor layer. The insulating material is, for example, in a tape shape (strip shape) so as to be easily wound. When the inner semiconductive layer is provided on the outer periphery of the superconducting conductor layer, the inner semiconductive layer may be formed by winding carbon paper or the like around the outer periphery of the superconducting conductor layer. At this time, the electrical insulating layer is formed on the outer periphery of the internal semiconductive layer. When an external superconducting layer is provided on the outer periphery of the electrical insulating layer, the external superconducting layer may be formed by winding a wire made of a superconducting material into a single layer or multiple layers in the same manner as the superconducting conductor layer. When the outer semiconductive layer is provided on the outer periphery of the electrical insulating layer, the outer semiconductive layer may be formed by winding carbon paper or the like around the outer periphery of the electric insulating layer. At this time, the external superconducting layer is formed on the outer periphery of the external semiconductive layer. Further, when a protective layer is provided on the outer periphery of the external superconducting layer, the protective layer can be formed by winding an insulating paper such as kraft paper around the outer periphery of the external superconducting layer. The heat insulation pipe for housing the cable core having the above configuration will be described later.

The cable core which has an electrically insulating layer is obtained by the above-mentioned procedure. In this invention, the process which reduces the water | moisture content contained in an electrical insulation layer is performed with respect to this cable core. Therefore, in the present invention, the cable core is allowed to be produced in the atmosphere. The present invention proposes heating the cable core in a vacuum state as the moisture reduction process. By heating the cable core, moisture contained in the electrical insulating layer is efficiently vaporized, and by performing evacuation, the vaporized gas (water vapor) can be efficiently removed outside the core. In order to perform this moisture reduction treatment, for example, a dry container that can be evacuated and heated is used. As the drying container, a bottomed cylindrical main body that can store the cable core, a lid that can be opened and closed with respect to the main body, a vacuum device that evacuates the main body with the lid closed, And a heating means for heating the core. If the cable core is wound around a drum, it can be easily stored in a drying container even if it is long. At this time, the drying container is rotatably disposed on the bottom surface of the main body, and includes a turntable on which the drum is mounted and a driving device that rotates the turntable. The drum is rotated by rotating the turntable by the driving device. It is made to rotate and set it as the structure by which a cable core is drawn | fed out to the inner pipe formation apparatus side mentioned later. A configuration in which a drum and a turntable are integrated may be used. At this time, for example, the cable core is once wound around another drum after being formed, and is wound around the drum of the turntable, or the formed core is wound around the drum of the turntable. The main body that houses the cable core is sealed by closing the lid. Although a heating part may be arrange | positioned inside a main body, it may be arrange | positioned outside a main body or a cover part, and the structure which heats a cable core via a main body or a cover part may be sufficient. In the latter case, a configuration in which a pipe is arranged along the outer periphery of the main body and the lid, and a heating fluid such as heated steam is introduced and circulated in the pipe, a configuration in which a heater is arranged on the outer periphery of the main body and the lid, etc. It is done. In order to reduce the moisture content of the electrical insulating layer using such a drying container, the cable core is housed in the main body, the lid is closed and the inside of the main body is sealed, and then the core is heated by the heating unit, This is done by evacuating the inside of the main body with a vacuum device. In this moisture reduction treatment, the degree of vacuum need only be such that the electrical insulating layer is properly dried, and not a high vacuum (about 1 × 10 ⁻³ to 1 × 10 ⁻⁵ Pa) as required for a heat insulating tube. However, a relatively low vacuum is sufficient. Specifically, about 1 × 10 ^{−1 to} 10 Pa is mentioned. The specific water content of the dried electrical insulating layer is about 3% by mass or less, preferably 0.1% by mass or less.

  The production method of the present invention can be applied not only to the production of a single-core cable having one cable core in a heat insulating tube, but also to the production of a multi-core cable having two or more cable cores. When manufacturing a multi-core cable, usually, after forming a cable core, a predetermined number of cores are twisted and stored in a heat insulating tube. Therefore, when manufacturing a multi-core cable, the moisture reduction treatment may be performed after twisting a predetermined number of cores, or the core subjected to the moisture reduction treatment may be twisted. In the latter case, it is preferable to prepare a predetermined number of cores that have been subjected to the moisture reduction treatment and subsequently perform twisting in a vacuum state. In order to twist multiple cable cores in a vacuum state, for example, a twisting machine used for twisting the cores is placed in the vacuum chamber for twisting, and this vacuum chamber is maintained in the same vacuum state as the drying container. To be configured. At this time, a plurality of cores are housed in one drying container and the moisture reduction treatment is performed, and the drying container is connected to the vacuum chamber for twisting so that each core is supplied to the twisting machine, Each core is housed in a separate drying container to perform the moisture reduction process, and the plurality of drying containers are connected to the twisting vacuum chamber so that each core is supplied to the twisting machine from each drying container. . The vacuum device provided in the drying container is adjusted so that each drying container and the twisting vacuum chamber have the same degree of vacuum. A vacuum device may be provided in the twisting vacuum chamber so that the degree of vacuum can be adjusted. The drying container and the twisting vacuum chamber may be connected by a guide pipe that maintains a vacuum state similar to that of the drying container, and the cable core may be introduced into the vacuum chamber through the pipe. A guide roller may be provided inside the guide pipe, and the cable core may be sent out to the twister side. Thus, in the case of a multi-core cable, after the cable core is formed, the twisting and moisture reduction treatment may be performed in a vacuum state, or after the core formation and twisting, the moisture reduction treatment may be performed in a vacuum state. .

  The cable core (including twisted stranded product) obtained as described above is housed in a heat insulating tube. This heat insulation pipe has a double structure consisting of an inner pipe and an outer pipe, and a vacuum is drawn between the inner pipe and the outer pipe. A heat insulating material layer made of a heat insulating material is provided on the outer periphery of the inner tube. When the cable core is housed in the heat insulation tube, in the present invention, after the electrical insulation layer is dried in the vacuum state as described above, the vacuum core is kept inside the outer periphery of the core while maintaining the vacuum state. Propose to form a tube. That is, in the present invention, after the moisture reduction treatment, the inner tube is formed without exposing the cable core to the atmosphere.

  As an inner tube forming method, an extrusion method in which the inner tube forming material is extruded and formed on the outer periphery of the cable core, or a plate-like material that forms the inner tube on the outer periphery of the core is arranged, and both edges of the plate-like material are arranged. And a welding method for forming the joint by welding the seam. In the former extrusion method, an inner tube is formed using an extruder. Here, if the inner tube is formed so that the inner peripheral surface of the inner tube is in close contact with the outer peripheral surface of the core, the space capacity surrounded by the outer peripheral surface of the core and the inner peripheral surface of the inner tube is insufficient, and the refrigerant is sufficiently supplied. There is a risk of being unable to circulate. Therefore, it is preferable to use an extruder that can form an inner pipe having a sufficient capacity in the space. More specifically, an extruder capable of forming a cylindrical inner tube having a predetermined clearance between the outer peripheral surface of the core and the inner peripheral surface of the inner tube is used. When the inner tube is formed by extrusion, examples of the forming material include a metal material having excellent flexibility such as lead and aluminum, and a metal material having excellent strength such as stainless steel. On the other hand, in the latter welding method, for example, an inner pipe is formed using a supply machine that supplies a plate-shaped material, a forming machine that curves the supplied plate-shaped material, and a welding machine that welds a seam of the plate-shaped material. Form. Also in the case of the welding method, it is formed so as to be an inner tube having a predetermined space as in the above extrusion method. When forming the inner tube by welding, the forming material includes a metal plate having excellent strength such as stainless steel.

  In order to form the inner tube as described above while maintaining the vacuum state after performing the moisture reduction treatment in a vacuum state, for example, an extruder or the like so as to maintain the same vacuum state as the drying container. An inner pipe forming device such as a welding machine is arranged. When forming an inner tube using an extruder, the extruder is connected to the drying container so that the portion where the core is inserted in the extruder is maintained in the same vacuum state as the drying container. A guide pipe that maintains a vacuum state similar to that of the drying container may be connected between the vacuum container and the extruder, and the cable core may be introduced into the extruder through this pipe. A guide roller may be provided inside the guide pipe, and the core may be sent out to the extruder side. The inner tube that has passed through the extruder is exposed to the atmosphere. Therefore, when the end portion is open, the cable core located at the inner tube end portion may absorb moisture in the atmosphere. Therefore, it is preferable to seal the end of the inner tube so that the end of the cable core does not come into contact with the atmosphere. This also applies to the welding method described later.

  Note that maintaining the same vacuum state as the drying container means that the degree of vacuum is substantially equal. Therefore, for example, the atmosphere in which the portion where the cable core is inserted in the drying container and the extruder may be the same, or in the case where the two are separated, the degree of vacuum of the two is about the same. Good. In the former case, for example, a vacuum device common to the drying container and the extruder is used so that the degree of vacuum is approximately the same. In the latter case, separate vacuum devices are provided, and each vacuum device is adjusted so that the degree of vacuum is approximately the same. Further, the degree of vacuum of each vacuum device may be varied within an allowable range. The matters described in this stage are the same in the case of the welding process described later.

  On the other hand, when forming an inner pipe by welding, an inner pipe forming device such as the above-described supply machine, molding machine, or welder is disposed in an inner pipe forming vacuum chamber, and the vacuum chamber is in a vacuum state similar to that of the drying container. Is configured to be maintained. The vacuum device provided in the drying container is adjusted so that each drying container and the inner tube forming vacuum chamber have the same degree of vacuum. This vacuum chamber may also be provided with a separate vacuum device so that the degree of vacuum can be adjusted. A guide pipe that maintains a vacuum state similar to that of the drying container is connected between the drying container and the inner tube forming vacuum chamber, and the cable core may be introduced into the vacuum chamber through the pipe. . A guide roller may be provided inside the guide pipe, and the core may be sent out to the inner tube forming apparatus side.

  The inner tube formed by the above-described extrusion method or welding method has a smooth flat tube with no irregularities on the surface. The inner tube may be a flat tube, but it is excellent in flexibility if it is a corrugated tube having a corrugated surface. When the inner tube is a corrugated tube, irregularities are formed on the surface of the flat tube by a corrugating machine (corrugator). The corrugation process may be performed in a vacuum state, but may be performed in the air because the cable core is performed after the cable core is covered with the inner tube. When the corrugation process is performed in a vacuum state, for example, a corrugator is disposed in the inner tube forming vacuum chamber.

  By the above process, a core integrated product in which the cable core is housed in the inner tube is obtained. In particular, the electrical insulation layer of the cable core in the obtained core integrated product is reduced in moisture content by the moisture reduction treatment, and the reduced state is maintained by subsequently forming the inner tube in a vacuum state. A heat insulating material is wound around the outer periphery of such a core integrated product to form a heat insulating material layer, and an outer tube is formed on the outer periphery thereof. The outer tube may be formed by extrusion similarly to the inner tube, or may be formed using welding. The material for forming the outer tube may be the same as that of the inner tube, and may be the same as or different from the inner tube. The outer tube may be a flat tube or a corrugated tube, and may have the same shape as the inner tube or a different shape. Examples of the heat insulating material include a material obtained by laminating a plastic mesh and a metal foil, for example, super insulation (hereinafter referred to as SI) in which aluminum is deposited on the surface of a polyester film. Such a heat insulating material is preferably in a tape shape (strip shape) so as to be easily wound around the outer periphery of the inner tube.

  The heat insulating material such as SI is easy to absorb moisture. For this reason, when the heat insulating material layer is formed in the atmosphere or the outer tube is formed in the air after the heat insulating material layer is formed, the moisture content of the heat insulating material layer may increase. Therefore, in the present invention, it is proposed to form the heat insulating material layer and the outer tube in a vacuum state to reduce the moisture content of the heat insulating material layer. That is, in the present invention, the outer tube is formed without exposing the heat insulating material layer to the atmosphere after the heat insulating material layer is formed.

In order to form the heat insulating material layer in a vacuum state, for example, a winding machine that winds the heat insulating material around the outer periphery of the inner tube is disposed in the vacuum chamber for forming the heat insulating material layer, and the heat insulating material is wound. Can be mentioned. This vacuum chamber is provided with a vacuum device capable of evacuation. For example, the inner tube is wound around a drum, and the drum is rotated, introduced into the vacuum chamber, and sent to the winding machine. At this time, the inlet of the inner tube in the vacuum chamber has a seal structure that does not break the vacuum state of the vacuum chamber. Alternatively, the drum may be stored in a vacuum chamber. When the heat insulating material layer is formed, the inner tube may be an integrated core in which the cable core is accommodated or a state in which the core is not accommodated. When forming the heat insulating material layer in a state where the core is not housed in the inner tube, the inner tube is prepared and wound around the drum, the inner tube is drawn out from this drum, the heat insulating material layer is formed on the outer periphery of the inner tube, and the outer periphery is formed on the outer tube. After forming the outer tube, the cable core is housed in the inner tube. As the winding machine, an apparatus usually used for forming a heat insulating material layer can be used. The degree of vacuum at the time of formation of the heat insulating material layer may be a level that allows the heat insulating material layer to be appropriately dried, and may be a relatively low vacuum instead of the high vacuum required for the heat insulating tube. Specifically, about 1 × 10 ^{−1 to} 10 Pa is mentioned.

  In the present invention, after forming the heat insulating material layer in a vacuum state as described above, the outer tube is formed while the vacuum state is maintained. The forming method and forming material of the outer tube may be the same as those of the inner tube described above. That is, an extrusion method or a welding method is used, or a metal material such as aluminum, lead, or stainless steel is used. Moreover, it is good to arrange | position an outer tube | pipe forming apparatus, such as an extruder and a welding machine, and to form an outer tube | pipe so that the vacuum state similar to the said vacuum chamber for heat insulating material layer formation may be maintained. For example, when forming an outer tube using an extruder, the place where a heat insulating material integrated body having a heat insulating material layer is inserted on the outer periphery of the inner tube in the extruder is the same vacuum state as the vacuum chamber for forming the heat insulating material layer The extruder is connected to the vacuum chamber so that the A guide pipe that maintains a vacuum state similar to that in the vacuum chamber may be connected between the vacuum chamber and the extruder, and the heat insulating material integrated product may be introduced into the extruder through the pipe. Further, a guide roller may be provided inside the guide pipe, and the inner tube may be sent out to the extruder side. The outer tube that has passed through the extruder is exposed to the atmosphere. Therefore, when the end portion is open, the heat insulating material layer located at the outer tube end portion may absorb moisture in the atmosphere. Therefore, it is preferable to seal between the inner tube and the outer tube at the end portions of the inner tube and the outer tube so that the heat insulating material layer does not come into contact with the atmosphere. This also applies to the welding method described later.

  On the other hand, when forming the outer tube by welding, for example, as in the case of the inner tube, an outer tube forming device such as a supply machine, a molding machine, and a welding machine is arranged in the outer tube forming vacuum chamber, and this vacuum chamber is A vacuum state similar to that of the vacuum chamber for forming the heat insulating material layer is maintained. The vacuum device provided in the heat insulating material layer forming vacuum chamber is adjusted so that the heat insulating material layer forming vacuum chamber and the outer tube forming vacuum chamber have the same degree of vacuum. The vacuum chamber for forming the outer tube may be provided with a separate vacuum device so that the degree of vacuum can be adjusted. Between the two vacuum chambers, a guide pipe that maintains a vacuum state similar to that of the vacuum chamber for forming the heat insulating material layer is connected, and the integrated heat insulating material is introduced into the outer tube forming vacuum chamber through this pipe It is good. The guide pipe may be provided with a guide roller, and the heat insulating material integrated product may be sent out to the outer tube forming apparatus side.

  The outer tube formed by the above-described extrusion method or welding method is a flat tube, like the inner tube. Similarly to the inner tube, the outer tube may be a flat tube or a corrugated tube. When the outer tube is a corrugated tube, a corrugating machine (corrugator) is used as in the case of the inner tube. The corrugation process may be performed in a vacuum state, but may be performed in the atmosphere because the corrugation process is performed after the heat insulating material layer is covered with the outer tube. When the corrugating process is performed in a vacuum state, for example, a corrugator is disposed in a vacuum chamber for forming an outer tube.

  By the above process, an outer tube integrated product having an outer tube on the outer periphery of the heat insulating material layer is obtained. In particular, in the obtained outer tube integrated product, the heat insulating material layer is formed in a vacuum state to reduce moisture content, and subsequently, the reduced state is maintained by forming the outer tube in a vacuum state. The In such an outer tube integrated product, when the inner tube is previously provided with a cable core, the inner tube and the outer tube are evacuated as described later. When the inner pipe does not have a cable core, the core is sent out by using a feeding device such as a pair of endless tracks, and the core is stored in the outer pipe integrated product. In this way, a superconducting cable in which the cable core is housed in the heat insulating tube is obtained.

The superconducting cable obtained as described above is evacuated to a predetermined degree of vacuum between the inner tube and the outer tube using a vacuum device. At this time, when the manufacturing method of the present invention in which the formation of the heat insulating material layer and the outer tube are performed in a vacuum state as described above is applied, the time for evacuation can be shortened. In addition, since the moisture content is low, a high degree of vacuum can be reached in a relatively short time, and a high vacuum state can be maintained for a long time after sealing the heat insulating tube. For example, the heat insulation tube of the superconducting cable obtained by the production method of the present invention has a vacuum state of about 1.3 × 10 ⁻³ MPa (1.0 × 10 ⁻⁵ torr) at room temperature, and even after sealing, 0.67 MPa (5.0 A vacuum state of about ^10-3 torr) can be maintained. This evacuation is performed by winding the superconducting cable around a drum and winding it around the drum, because both ends of the cable are relatively close even if the cable is long. Evacuation (exhaust) can be performed, and the vacuuming time can be further shortened. Moreover, if it winds around a drum, it can preserve | save as it is in a warehouse after evacuation, or can be conveyed to the construction site.

  Superconducting cable obtained by reducing the moisture content of the electrical insulating layer and forming the inner tube under specific conditions, and reducing the moisture content of the heat insulating material layer and forming the outer tube under specific conditions Is a state in which the moisture content of the electrical insulating layer and the heat insulating material layer is reduced. Therefore, this superconducting cable can reach a desired degree of vacuum in a short time, and the time for evacuation can be shortened. Also, in the power supply line using this superconducting cable, the moisture contained in the electrical insulating layer is solidified during operation, and the refrigerant transport path is not blocked by the solidified moisture, and a high vacuum state is maintained for a long time. It has a special effect of being done.

  After constructing the line with a superconducting cable in which the heat insulating tube is evacuated, the line is operated by filling and circulating a refrigerant such as liquid nitrogen in the inner tube.

  As described above, according to the method for manufacturing a superconducting cable of the present invention, when the cable is manufactured, the moisture content of the electrical insulating layer and the heat insulating material layer is reduced by making a vacuum state, thereby preventing a problem caused by excessive moisture content. Can be prevented. For example, by using the manufacturing method of the present invention in which the inner tube is formed so that the moisture content of the electrical insulation layer is reduced and the state is maintained, a superconducting cable having a very small moisture content of the electrical insulation layer of 0.1 mass% or less Can be provided. Such a superconducting cable can effectively prevent the moisture contained in the electrical insulating layer from being solidified by the refrigerant during operation and blocking the refrigerant transport path by the solidified moisture.

  Moreover, the superconducting cable in which the moisture content of the heat insulating material layer is very small can be provided by the manufacturing method of the present invention in which the outer tube is formed so that the moisture content of the heat insulating material layer is reduced and the state is maintained. . Such a superconducting cable can shorten the evacuation time as compared with the conventional case when evacuating the inner tube and the outer tube after forming the outer tube. In addition, the superconducting cable that has been evacuated maintains a high vacuum state for a long period of time.

  Embodiments of the present invention will be described below.

  First, the manufacturing method of the present invention for forming the inner pipe of the heat insulating pipe while maintaining the reduced state after performing the process of reducing the moisture content of the electrical insulating layer will be described. This manufacturing method is to manufacture a superconducting cable 100 including a cable core 110 having a superconducting conductor layer 112 as shown in FIG. 3 and a heat insulating tube 120 for housing the core 110. The core 110 includes a former 111, a superconducting conductor layer 112, an electric insulating layer 113, an outer superconducting layer 114, and a protective layer 115 in order from the center, and the heat insulating tube 120 has a double structure including an inner tube 121 and an outer tube 122. is there. The present invention is particularly characterized in that a specific treatment is performed on the electrical insulating layer 113 and that the inner tube 121 of the heat insulating tube 120 is formed under specific conditions. In the manufacturing method of the present invention, the superconducting cable is formed by the procedure of core formation → moisture reduction treatment of the electrical insulating layer → formation of the heat insulating tube. Note that after the heat insulating tube is formed, the heat insulating tube is evacuated. The superconducting cable having a vacuum heat insulating tube is laid to construct a power supply line, and this line is operated by circulating a refrigerant such as liquid nitrogen between the inner tube 121 of the heat insulating tube 120 and the core 110. Is done. Hereinafter, the manufacturing procedure of the superconducting cable will be specifically described.

[Formation of core]
<Former formation>
The cable core 110 is formed in order from the center. First, the former 111 is formed. The former 111 is a member that serves as a core for retaining the superconducting conductor layer 112. When the fault current flows through the conductor layer 112, the former 111 serves as a flow path, and has a function of suppressing damage to the conductor layer 112. The former 111 has a stranded wire structure formed by twisting a plurality of coated strands in which an enamel insulating coating is applied to a copper wire.

<Formation of superconducting conductor layer>
Next, a superconducting conductor layer 112 is formed on the outer periphery of the former 111. The superconducting conductor layer 112 is formed by using a Bi2223-based Ag alloy sheath tape wire manufactured by a pressure sintering method, and winding the tape wire on the former 111 in multiple layers (four layers in this example). The winding direction of each layer is SSZZ in order from the inner layer side.

<Formation of electrical insulation layer>
Next, an electrical insulating layer 113 is formed on the outer periphery of the superconducting conductor layer 112. In this example, an inner semiconductive layer (not shown) is provided on the inner peripheral side of the insulating layer 113. Therefore, carbon paper is wound on the superconducting conductor layer 112 to form an internal semiconductive layer. An electrically insulating layer 113 is formed on the internal semiconductive layer. The electrical insulating layer 113 is formed by winding an insulating material around the inner semiconductive layer in multiple layers. As the insulating material, PPLP (registered trademark) in which polypropylene and kraft paper are bonded is used, and is dried in advance before winding. The electrical insulating layer 113 is formed in a paper winding chamber in which humidity can be adjusted. In this example, the humidity of the paper winding chamber is 20 to 30%. Other than the electrical insulating layer 113, that is, the former 111, the superconducting conductor layer 112, the inner semiconducting layer, the outer semiconducting layer described later, the outer superconducting layer 114, the protective layer 115, and the core are twisted in a normal atmosphere. To do.

<Formation of external superconducting layer>
Next, the external superconducting layer 114 is formed on the outer periphery of the electrical insulating layer 113. The external superconducting layer 114 is a shield that prevents the leakage of a magnetic field to the outside by canceling out the magnetic field generated by the superconducting conductor layer 112 when an alternating current is induced in an alternating current in the same direction as the superconducting conductor layer 112 in the reverse direction. It functions and can be used as a return path when the superconducting conductor layer 112 is used as a forward path in DC power transmission. In this example, an external semiconductive layer (not shown) is provided on the outer peripheral side of the electrical insulating layer 113. Therefore, carbon paper is wound on the electrical insulating layer 113 to form an external semiconductive layer, and the external superconducting layer 114 is formed on the external semiconductive layer. The external superconducting layer 114 is formed by winding a tape wire made of a superconducting material obtained by the pressure sintering method similar to the superconducting conductor layer 112 on the external semiconductive layer in multiple layers (two layers in this example). To do. The winding direction of each layer is SS.

<Formation of protective layer>
Next, the protective layer 115 is formed on the outer periphery of the external superconducting layer 114. This protective layer 115 provides mechanical protection for the outer superconducting layer 114 and is formed of an insulating material to electrically insulate between the superconducting layer 114 and the heat insulating pipe (inner pipe 121). It is possible to prevent the induced current and the return current from being shunted to 120. Therefore, in this example, the protective layer 115 is formed by winding kraft paper on the external superconducting layer 114.

<Core twisting>
Thus, the cable core 110 is formed. In this example, in order to obtain a three-core cable as shown in FIG. 3, three such cores 110 are prepared, and these cores 110 are twisted with a twisting machine to form a twisted product. The obtained twisted product is wound up on a drum. In this example, a twisted product is used. However, when a single-core cable having one core 110 is provided, one core 110 may be prepared and wound around a drum.

[Reduction of moisture content in electrical insulation layer]
Next, the twisted product of the core 110 is subjected to a treatment for reducing the moisture content of the electrical insulating layer 113. In this example, the electrical insulating layer 113 is formed using a pre-dried insulating material, but since each layer on the outer periphery of the insulating layer 113 is formed in the air after that, during the formation of these layers The insulating layer 113 absorbs moisture. Therefore, after forming the twisted product, a treatment for reducing or removing moisture contained in the electrical insulating layer 113 is performed. In particular, this process is performed in a vacuum state. Then, in order to prevent the electrical insulating layer 113 from absorbing moisture again when the inner tube 121 is formed in the heat insulating tube 120, the inner tube 121 is subsequently formed while maintaining the vacuum state during the processing.

<Description of the device>
First, an apparatus used for the moisture reduction process and the formation of the inner tube will be described, and then a specific procedure will be described. FIG. 1 is a schematic configuration diagram of an apparatus used in the method for manufacturing a superconducting cable of the present invention. This apparatus can store a cable core (twisted product 1) and can be evacuated and heated, and an extruder 20 that forms an inner tube on the outer periphery of the core sent out from the drying container 10. A guide pipe 30 is provided between the drying container 10 and the extruder 20 and connects the two. Drying vessel 10 has a twisted product 1 bottomed tubular body 11 capable of housing a wound on the drum D _1, lid mounted openably to the main body 11 (not shown), the lid portion a vacuum device V ₁ evacuating the inside of the main body 11 in the closed state, is arranged on the outer circumference of the outer periphery and the lid portion of the main body 11 comprises a pipe 12 in which the heating steam is circulated. The drying container 10 can seal the inside of the main body 11 by closing the lid with respect to the main body 11. Further, by driving the vacuum device V ₁ in a sealed state, it is possible to the inside of the main body 11 in a vacuum state. Furthermore, the twisted product 1 can be heated via the main body 11 and the lid by introducing the heating steam from the supply unit 13 connected to the pipe 12 and circulating the heating steam through the pipe 12. . A drum D ₁ is mounted on the bottom surface of the main body 11, and a rotatable turntable (not shown) is disposed. The turntable is rotated by the driving device M. This rotation can be delivered sequentially extruder 20 side twisted product 1 wound on the drum D _1. In order to ensure that the twisted product 1 can be inserted through the guide pipe 30, a separate delivery device may be disposed in the main body 11 near the opening to which the pipe is connected. The guide pipe 30 connected to the drying container 10 has a configuration in which the internal space has a common atmosphere with the main body 11, and when the main body 11 is in a vacuum state, the vacuum state is similarly maintained. A valve (not shown) is provided on the drying pipe 10 side of the guide pipe 30 so that the gas flow between the pipe 30 and the container 10 can be stopped. The guide pipe 30 includes a guide roller (not shown) that feeds the core. When the main body 11 is in a vacuum state, the extruder 20 connected to the guide pipe 30 keeps the same vacuum state as that of the main body 11 in the same manner as the pipe 30 and is placed inside the outer periphery of the twisted product 1 through the pipe 30. It is the structure which can form a pipe | tube. Specifically, the extruder 20 is connected to the pipe 30 so that the space where the twisted product 1 is inserted in the extruder 20 has an atmosphere common to the main body 11. The extruder 20 used in this example forms an inner tube in a cylindrical shape having a predetermined clearance between the outer peripheral surface of the core 110 (twisted product) and the inner peripheral surface of the inner tube 121 as shown in FIG. It is supposed to be possible.

<Processing procedure>
A processing procedure for reducing the moisture content of the electrical insulating layer will be described using the apparatus shown in FIG. First, open the lid of the drying vessel 10, mounted on a turntable disposed a drum D ₁ which Yogobutsu 1 is wound on the bottom of the body 11 to seal the main body 11 close the lid. At this time, the valve of the guide pipe 30 is closed, and the pipe 30 and the container 10 are separated. In this state, heating steam is introduced from the supply unit 13, the heating steam is circulated through the pipe 12, and the twisted product 1 is heated via the drying container 10. By this heating, moisture contained in the electrical insulating layer of the twisted product 1 is vaporized and released into the main body 11. After passing the heating steam for a predetermined time, the valve provided between the supply unit 13 and the pipe 12 is closed, and the valve provided between the vacuum device V ₁ and the main body 11 is opened, and the vacuum device V ₁ is driven and the inside of the main body 11 is evacuated to a vacuum state. By this evacuation, moisture released into the main body 11 is released out of the drying container 10 and is prevented from entering again into the electrical insulating layer. While driving the vacuum device V _1, by opening the valve of the guide pipe 30, the pipe 30 and the extruder 20 also set to be the same vacuum state as the main body 11. When the moisture content in the electrical insulating layer 113 is sufficiently reduced, the twisted product 1 is sent to the extruder 20 through the guide pipe 30 to form an inner tube on the outer periphery of the twisted product 1.

[Formation of insulation pipe]
<Formation of inner tube>
The twisted product 1 in which the moisture content of the electrical insulating layer is reduced in the drying container 10 is sent to the extruder 20 through the guide pipe 30 in the vacuum state, and the inner tube is formed on the outer periphery thereof to form the drum D. Wind up to ₂ . In the extruder 20, the place where the twisted product 1 is inserted, more specifically, the space from the introduction port to which the twisted product 1 is introduced to the discharge port, is in a vacuum state like the drying container 10. In this example, aluminum is used as a material for forming the inner tube. During inner tube formation drives the vacuum device V ₁ appropriately kept as a vacuum state is maintained. The core integrated product 2 having an inner tube on the outer periphery of the twisted product 1 is exposed to the atmosphere after passing through the extruder 20. Therefore, the end of the inner tube is sealed so that the twisted material does not absorb moisture again. In this way, by forming the inner tube in a vacuum state following the moisture reduction process, the electrical insulating layer is maintained in a state where moisture is reduced. Note that the downstream side of the extruder 20 (drum D ₂ side), place the corrugator (not shown), a flat tube formed by an extruder 20, subjected to a corrugating process in corrugator waves inner tube It has become a tube. In this example, the corrugator is provided, but the inner tube may be a flat tube without providing the corrugator. Core integrated product 2 that has been processed corrugated is wound by a drum D _2.

<Formation of insulation layer>
Next, a heat insulating material layer is formed on the outer periphery of the core integrated product 2. In this example, using a polyester film super insulation with a deposit of aluminum on the surface of the (trade name) as insulation, feed the core monolith 2 wound by rotating the drum D _2, by a general winding machine The heat insulating material is wound around the outer periphery of the core integrated product 2 to form a heat insulating material layer.

<Formation of outer tube>
Next, an outer tube is formed on the outer periphery of the heat insulating material layer. In this example, the outer tube is formed following the formation of the heat insulating material layer. In this example, the outer tube is formed by welding. Specifically, a supply machine for supplying a plate material, a molding machine for bending the supplied plate material, and a welding machine for welding a seam of the plate material are prepared. The flat tube is formed by supplying, arranging on the outer periphery of the heat insulating material layer, curving the plate with a molding machine, and welding the seam with a welding machine. Further, a corrugator is disposed on the downstream side of the welder, and the corrugator is used to corrugate the flat tube to form an outer tube of the corrugated tube. The outer tube may be a flat tube without providing a corrugator. The cable integrated product including the outer tube is wound up with a separately prepared drum after formation. Note that the inner tube and the outer tube are sealed at the end portions of the inner tube and the outer tube. In this example, the outer tube is formed by welding, but it may be formed by extrusion in the same manner as the inner tube.

<Formation of anticorrosion layer>
In this example, an anticorrosion layer is further provided on the outer periphery of the outer tube. Polyvinyl chloride is used as a material for forming the anticorrosion layer, the cable integrated product is fed out from a drum, and the anticorrosion layer is formed by extruding the formation material to the outer periphery of the outer tube by a general extruder. Through the above steps, a superconducting cable in which the cable core is housed in the heat insulating tube is obtained. The obtained superconducting cable is wound around a separately prepared drum after the formation of the anticorrosion layer.

[Vacuum insulation tube]
Next, the heat insulating tube is evacuated in the superconducting cable. The evacuation is performed in a state where the superconducting cable is wound around the drum. Specifically, a vacuum device prepared separately is connected to both ends of the superconducting cable, and suction (exhaust) is performed from both sides. When the heat insulation tube reaches a predetermined degree of vacuum, evacuation is stopped and both ends of the heat insulation tube are sealed. By this step, a superconducting cable having a vacuum heat insulating tube is obtained.

[Railway operation]
The superconducting cable obtained by the above procedure is laid and used for the power supply line. This line is operated by circulating a refrigerant such as liquid nitrogen in the inner pipe. In the superconducting cable obtained by the manufacturing method of the present invention, moisture contained in the electrical insulating layer is reduced as compared with the cable obtained by the conventional method. Therefore, even when the inner pipe is filled with a refrigerant and the electric insulation layer is impregnated with the refrigerant during line operation, moisture contained in the insulation layer is solidified by the refrigerant, and the solidified product is transported by the refrigerant. Problems such as blocking the refrigerant transport path can be effectively prevented.

  Next, the manufacturing method of the present invention for forming the outer pipe of the heat insulating pipe while maintaining the reduced state after forming the heat insulating material layer so as to reduce the moisture content will be described. This manufacturing method is to manufacture a superconducting cable 100 as shown in FIG. 3 in the same manner as in Example 1, and in particular, in that the outer tube 122 of the heat insulating material layer and the heat insulating tube 120 is formed under specific conditions. Has characteristics. Here, the method for forming a heat insulating tube will be mainly described.

  In the first embodiment, the case where the heat insulating material layer is formed in the atmosphere has been described. However, depending on the material of the heat insulating material, there is a material that easily absorbs moisture in the atmosphere. If the heat insulating material layer is formed in the air, the heat insulating material layer may absorb moisture excessively. Therefore, in this example, the heat insulating material layer is formed in a vacuum state so that the moisture content of the heat insulating material layer is reduced. Then, in order to prevent the heat insulating material layer from absorbing moisture again when the outer tube 122 is formed, the outer tube 122 is subsequently formed while maintaining this vacuum state.

<Description of the device>
First, an apparatus used for forming the heat insulating material layer and the outer tube will be described, and then a specific procedure will be described. FIG. 2 is a schematic configuration diagram of an apparatus used in the method for manufacturing a superconducting cable of the present invention. This device can accommodate the winding machine 40 of the heat insulating material I and can be evacuated, and an inner tube (heat insulating material integrated product 4) including a heat insulating material layer fed from the vacuum chamber 50. It includes an extruder 21 that forms an outer tube on the outer periphery, and a guide pipe 31 that is disposed between the vacuum chamber 50 and the extruder 21 and connects the two. The winding machine 40 includes a pad 41 that sequentially feeds the wound heat insulating material I to the outer periphery of the inner tube 3, and a pedestal 42 that rotatably holds the pad 41. One pedestal 42 is provided with a plurality of pads 41 (two in FIG. 2), and has a through-hole through which the inner tube 3 is inserted at the center thereof. A plurality of such pedestals 42 are arranged along the traveling direction of the inner tube 3 (two are shown in FIG. 2) to constitute a winding machine group. These winding machines 40 include a driving device (not shown) and automatically wind a heat insulating material around the outer periphery of the inner tube 3 that comes out of the through hole. By these winding machines 40, the heat insulating material can be wound in multiple layers around the outer periphery of the inner tube 3. The vacuum chamber 50 in which the winding machine 40 is housed is an extruder for a vacuum device V ₂ that evacuates the interior, an inlet for introducing the inner tube 3, and a heat insulating material integrated material 4 in which a heat insulating material layer is formed. It has a discharge port that discharges to the 21 side. The vacuum chamber 50, by driving the vacuum device V _2, can be the internal vacuum state. A delivery device (not shown) is arranged on each of the introduction port side and the discharge port side. With this delivery device, the inner tube 3 is introduced into the vacuum chamber 50 and the heat insulating material integrated product 4 is sent to the extruder 21. Can do. The introduction port includes a plug part (not shown) that can be freely opened and closed, and the vacuum chamber 50 can be sealed by closing the plug part and a valve (not shown) of a guide pipe 31 described later. The guide pipe 31 connected to the vacuum chamber 50 has a configuration in which the internal space has a common atmosphere with the vacuum chamber 50, and when the vacuum chamber 50 is in a vacuum state, the vacuum state is similarly maintained. . A valve is provided on the vacuum chamber side of the guide pipe 31 so that the gas flow between the pipe 31 and the vacuum chamber 50 can be stopped. A guide roller may be provided inside the guide pipe 31 for feeding the heat insulating material integrated product 4 to the extruder side. When the vacuum chamber 50 is in a vacuum state, the extruder 21 connected to the guide pipe 31 maintains the same vacuum state as the vacuum chamber 50 in the same manner as the pipe 31, and the heat insulating material integrated product 4 that has passed through the pipe 31. It is comprised so that an outer tube | pipe can be formed in the outer periphery. Specifically, the extruder 21 is connected to the pipe 31 so that the space where the heat insulating material integrated body 4 is inserted in the extruder 21 has a common atmosphere with the vacuum chamber 50. The extruder 21 used in this example is a predetermined clearance between the outer peripheral surface of the heat insulating material integrated product 4 and the inner peripheral surface of the outer tube, similarly to the extruder 20 (see FIG. 1) used in Example 1. The outer tube can be formed in a cylindrical shape having

<Formation procedure>
<Formation of insulation layer>
The procedure for forming the heat insulating material layer and the outer tube will be described using the apparatus shown in FIG. First, the stopper of the inlet and the valve of the guide pipe 31 are closed, the pipe 31 and the vacuum chamber 50 are separated, and the vacuum chamber 50 is sealed. In this state, by driving the vacuum device V _2, a vacuum state by evacuating the vacuum chamber 50. When the predetermined vacuum state is reached, the inlet is sealed so that the vacuum state of the vacuum chamber 50 is not broken when the inner tube 3 is introduced into the vacuum chamber 50, and the inner tube 3 is introduced into the vacuum chamber 50 from the inlet. To do. The inner tube 3 is previously produced separately and set aside around the drum D _3. Then, while rotating the drum D ₃ , the inner tube 3 is introduced into the vacuum chamber 50 by the delivery device and passed through the winding machine 40, and a heat insulating material layer is formed on the outer periphery of the inner tube 3. At this time, since the heat insulating material layer is formed in a vacuum atmosphere, it is less likely to absorb moisture compared to the case where it is formed in the air, and effectively suppresses excessive moisture during the layer formation. be able to. Moreover, even if the heat insulating material contains moisture in advance, the water is easily vaporized and released to the outside of the heat insulating material by making a vacuum state. Therefore, the heat insulating material in a state where moisture is reduced can be used, and the heat insulating material layer is formed in a vacuum state, so that the moisture content of the heat insulating material layer can be reduced even during the formation. Heat insulating material layer formed drives the vacuum device V ₂ appropriately kept as a vacuum state is maintained. When the formation of the heat insulating material layer is started, the valve of the guide pipe 31 is also opened so that the inside of the pipe 31 and the extruder 21 are in a vacuum state similar to the vacuum chamber 50. And an outer tube | pipe is formed in the outer periphery of the heat insulating material integrated material 4 in which the heat insulating material layer was formed.

<Formation of outer tube>
The heat insulating material integrated body 4 including the heat insulating material layer in which moisture is reduced in the vacuum chamber 50 is sent to the extruder 21 through the guide pipe 31 in the vacuum state, and an outer tube is formed on the outer periphery thereof. To do. In the extruder 21, the place where the heat insulating material integrated product 4 is inserted, more specifically, the space from the introduction port through which the integrated product 4 is introduced to the discharge port, is in a vacuum state as in the vacuum chamber 50. In this example, stainless steel is used as a material for forming the outer tube. The outer tube integrated body 5 in which the outer tube is formed on the outer periphery of the heat insulating material layer is exposed to the atmosphere after passing through the extruder 21. Therefore, the end portions of the inner tube and the outer tube are sealed between the inner tube and the outer tube so that the heat insulating material layer does not absorb moisture again. In this way, after the heat insulating material layer is formed in a state where moisture is reduced, the heat insulating material layer is maintained in a state where water content is reduced by subsequently forming the outer tube in a vacuum state. In addition, a corrugator (not shown) is arranged downstream of the extruder 21 (drum D ₄ side), the corrugator is used to corrugate the flat pipe formed by the extruder 21, and the outer pipe is corrugated. Try to be a tube. The outer tube may be a flat tube without providing a corrugator. Corrugated processed outer tube integrated product 5 after formation, wound by a drum D ₄ which is separately prepared.

  The inner tube 3 may be in a state in which the cable core is accommodated as in the first embodiment, or may be in a state in which the core is not accommodated. In the former case, the cable core may be formed according to the procedure of the first embodiment, or a cable core formed by a procedure similar to the conventional method may be used. In the latter case, after forming the heat insulation pipe by the above procedure, the cable core may be inserted and disposed in the heat insulation pipe using a core feeding device such as a pair of endless tracks. When the cable core is housed, a superconducting cable can be obtained by providing an anticorrosion layer on the outer periphery of the outer tube in the same manner as in Example 1.

  The resulting superconducting cable is evacuated in the same manner as in Example 1 above. At this time, in the superconducting cable obtained by the above procedure, the moisture contained in the heat insulating material layer is reduced as compared with that obtained by the conventional method. Therefore, when evacuating the heat insulating tube, the time can be shortened. In addition, since the moisture content of the heat insulating material layer is relatively small, a predetermined degree of vacuum can be reached in a short time. Furthermore, since the moisture content of the heat insulating material layer is relatively small, the degree of vacuum attainment and the degree of stop vacuum can be improved. Accordingly, since the degree of vacuum reduction is reduced after sealing the heat insulating tube, the superconducting cable obtained by the above procedure can maintain a high vacuum state for a long period of time.

  Needless to say, the superconducting cable may be manufactured by combining the first embodiment and the second embodiment. That is, after producing the cable core, the moisture content of the electrical insulating layer is reduced by vacuum and heating in the drying container 10 (FIG. 1), and the inner tube is connected by the extruder 20 (the same) while maintaining this vacuum state. Form. Next, the core integrated product 2 (same) in which the cable core is housed in the inner tube is introduced into the vacuum chamber 50 (FIG. 2), and a heat insulating material layer is formed on the outer periphery of the inner tube in a vacuum state. Reduce moisture content. An outer tube is formed by the extruder 21 (same as this) while maintaining this vacuum state.

  The superconducting cable obtained by the above procedure can shorten the time required for evacuating the heat insulating tube as described above, and can further increase the degree of vacuum achieved. Also, with such a superconducting cable, the refrigerant transport path is hardly blocked during operation, and a high vacuum state can be maintained for a long time.

  The manufacturing method of the superconducting cable of the present invention can be suitably used for manufacturing a superconducting cable used for AC power transmission or DC power transmission.

It is a schematic block diagram of the apparatus used for the manufacturing method of this invention superconducting cable which reduces the moisture content of an electrical insulating layer, and forms an inner pipe | tube in a vacuum state. It is a schematic block diagram of the apparatus used for the manufacturing method of this invention superconducting cable which reduces the moisture content of a heat insulating material layer, and forms an outer tube | pipe in a vacuum state. FIG. 2 is a cross-sectional view of a three-core batch type superconducting cable.

Explanation of symbols

1 Twisted product 2 Core integrated product 3 Inner tube 4 Heat insulation integrated product 5 Outer tube integrated product
10 Drying container 11 Body 12 Piping 13 Supply section
20,21 Extruder 30,31 Guide pipe 40 Winder 41 Pat 42 Pedestal
50 vacuum chamber
100 Superconducting cable 110 Core 111 Former 112 Superconducting conductor layer
113 Electrical insulation layer 114 External superconducting layer 115 Protective layer 120 Heat insulation pipe 121 Inner pipe
122 Outer pipe 123 Anticorrosion layer

Claims (5)

A superconducting cable manufacturing method comprising a cable core having an electrical insulating layer on the outer periphery of a superconducting conductor layer, a double structure composed of an inner tube and an outer tube, and a heat insulating tube for housing the core,
A process of forming an electrical insulating layer by winding an insulating material using insulating paper around the outer periphery of the superconducting conductor layer, and forming a cable core;
Heating the cable core in a first vacuum state to reduce the moisture content in the electrical insulating layer;
A superconducting cable manufacturing method comprising: forming an inner tube on the outer periphery of the cable core while maintaining the first vacuum state. Further, in the second vacuum state, a heat insulating material is wound around the outer periphery of the inner tube to form a heat insulating material layer, and the moisture content in the heat insulating material layer is reduced,
2. The method of manufacturing a superconducting cable according to claim 1, further comprising a step of forming an outer tube on an outer periphery of the heat insulating material layer while maintaining the second vacuum state.   3. The method of manufacturing a superconducting cable according to claim 1, wherein at least one of the inner tube and the outer tube is formed by extrusion.   3. The method of manufacturing a superconducting cable according to claim 1, wherein at least one of the inner tube and the outer tube is formed by welding a plate material made of a metal material. A superconducting cable manufacturing method comprising a cable core having a superconducting conductor layer, a double structure composed of an inner tube and an outer tube, and a heat insulating tube for housing the core,
In a third vacuum state, a step of forming a heat insulating material layer by winding a heat insulating material around the outer periphery of the inner tube, and reducing moisture contained in the heat insulating material layer;
A method of manufacturing a superconducting cable, comprising: forming an outer tube on the outer periphery of the heat insulating material layer while maintaining the third vacuum state.

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