JP5432807B2 - Superconducting cable connection structure - Google Patents

Description

  The present invention relates to a connection structure for a superconducting cable. In particular, the present invention relates to a superconducting cable connection structure suitable for adjusting the length of a heat insulating tube by cutting the end portion of the heat insulating tube of the superconducting cable when constructing the connection structure after laying the superconducting cable.

  Superconducting cables are expected as an energy-saving technology because they can transmit a large amount of power with low loss compared to existing normal conducting cables (eg, CV and OF cables). Recently, a superconducting cable is laid on a line simulating a real line, and a verification test is being conducted.

For superconducting cables, a cable core having a superconducting conductor is housed in a heat insulation pipe having a double pipe structure having an inner pipe and an outer pipe, and a refrigerant (eg, liquid nitrogen (LN ₂ )) is circulated in the heat insulation pipe. Thus, a structure having a superconducting state by cooling the superconducting conductor is representative. In addition, in order to enhance the heat insulation, the heat insulation pipe is kept in a vacuum between the inner pipe and the outer pipe, and this space forms a vacuum heat insulation space at both ends of the heat insulation pipe. Is provided with a sealing member for sealing the space. Here, the sealing members at both ends of the heat insulating tube are provided with a vacuum port communicating with the vacuum heat insulating space, and the vacuum heat insulating space is evacuated from the vacuum port (see, for example, Patent Document 1). Normally, this evacuation is performed in a factory that manufactures a superconducting cable, and is performed after performing a baking process for removing moisture existing in the vacuum heat insulation space and gas adsorbed on the inner tube and the outer tube. Generally, the vacuum port is accommodated in the clearance of the heat insulation pipe (the interval between the inner pipe and the outer pipe), has a diameter of about 15 mm, and is provided in a plurality so as to protrude in the axial direction of the heat insulation pipe.

  Moreover, the unit length of a superconducting cable is limited for reasons such as manufacturing, transportation, and laying (see, for example, Patent Document 2). For this reason, when constructing a transmission line over a long distance using a superconducting cable, an intermediate connection part that connects the cable core ends of the superconducting cable in the middle of the line, or a cable of the superconducting cable at the end of the line The terminal connection part which connects a core edge part to another electric power apparatus (for example, circuit breaker) is needed (henceforth, an intermediate | middle connection part and a terminal connection part are only called a core connection part). Referring to FIG. 6, the formation of the core connection portion 1j that connects the end portion of the cable core 1 of the superconducting cable 10 and the connection target is usually performed from the end portion of the heat insulating tube 2 to the end portion of the cable core 1. This is done by connecting the drawn and exposed superconducting conductor and the connection object via a conductive connecting member, and winding insulating paper around the outer periphery to form a reinforcing insulating layer. Then, a refrigerant container 31 that houses the core connecting portion 1j is attached to the inside (inner pipe 21) of the heat insulating pipe 2, and a vacuum container 32 that houses this refrigerant container 31 is further placed outside (the outer pipe 22) of the heat insulating pipe 2. Install the connection structure 3 by attaching. This vacuum vessel 32 is composed of a cylindrical portion 32p and a flange portion 32f, and is attached to the outer tube 22 of the heat insulating tube 2 by welding the flange portion 32f to the base 30 attached to the outer tube 22 of the heat insulating tube 2. It has been. In addition, a vacuum port (not shown) provided in the sealing member 20 at the end of the heat insulating tube is drawn out from the vacuum vessel 32, and the vacuum heat insulating space of the heat insulating tube 2 is formed during and after the connection structure is constructed. This is used to check the degree of vacuum.

  By the way, when manufacturing the superconducting cable, considering the construction of the connection structure, the end of the cable core is drawn from the end of the heat insulating tube, and the length of the cable core is longer than the design length of the heat insulating tube. It is designed to be longer by a predetermined length. For example, a conventional general superconducting cable is designed such that the distance from the end of the cable core to the end of the heat insulating tube is about 2000 mm to 5000 mm. Then, spot welding for the straight first protective tube and corrugated second protective tube for protecting the vacuum port and the cable core end at the end of the heat insulating tube, considering removal in a later process. To join each. Further, the connecting pipe attached to the pooling eye is welded to the end of the second protective pipe to attach the pooling eye and wind it around the drum. Usually, the length of the straight tube (first protective tube) is designed to be a length corresponding to the vacuum port (about 150 mm to 300 mm).

  Moreover, when putting a superconducting cable into practical use, it has been studied to use it as a replacement for a normal conducting cable laid in an existing underground conduit. When laying a superconducting cable in a conduit, the superconducting cable is drawn into the conduit by pulling a pooling eye attached to one end of the superconducting cable (see, for example, Patent Documents 2 and 3).

JP 2006-197702 A (paragraph 0014) JP 2007-287388 A (paragraphs 0015 and 0030) JP 2009-124855 A

  However, the conventional superconducting cable has the following problems.

(1. The problem that the length of the heat insulation pipe cannot be adjusted)
As shown in FIG. 6, for example, the end of the superconducting cable laid in the pipe is drawn into the manhole M from the pipe T, and the connection structure is constructed in the manhole M. When constructing a connection structure, it was conventionally considered to adjust the length of the cable core by cutting the end of the cable core. Since the heat insulating space is formed, it has not been considered to adjust the length by cutting the end portion. Therefore, conventionally, when a superconducting cable is manufactured, the length of the heat insulating tube is designed to be equal to the laying length (actual laying length) required when laying.

  When laying a superconducting cable in a pipeline, conventionally, the length of the pipeline is measured in advance, and the design length of the superconducting cable (cable core and insulated pipe) to be manufactured is determined based on the measured length. Yes. However, since the space in the manhole and the size of the refrigerant container or vacuum container of the connection structure are determined, if the measurement error is large, the connection structure may not be constructed. That is, if the difference between the design length of the heat insulation pipe and the actual installation length is large, the connection structure cannot be constructed. For example, manhole length Lm = 10000 mm, connection structure length Lj = 5500 mm, length Lip from the end of the insulation tube to the vacuum vessel mounting position Lip = 500 mm, and the opening of the pipe line from the vacuum vessel mounting position When the length Lpw to the wall surface of the formed manhole is 2250 mm, the error range of the measurement length (design length) is required to be within ± 100 mm. Therefore, it is necessary to measure the pipe length with high accuracy, and it is desirable to obtain it by actual measurement, but it is difficult to measure if the pipe is bent or inclined, and as a result, it is difficult to measure the pipe length. It can take a lot of time.

(2. The problem that the cable tip jumps out of the drum)
The distance from the tip of the pooling eye to the end of the heat insulation pipe is several meters, and a straight pipe (first protective pipe) is connected to the end of the heat insulation pipe. Unlike the location of the corrugated tube, this straight tube location is not bent, so it is difficult to fit the tip portion extending from the straight tube toward the pooling eye into the outer shape of the drum.

(3. Problem of bending at the end of the installed cable)
When laying a superconducting cable in the pipeline, in addition to pulling the pooling eye attached to the tip of the cable, it is supplied to a vendor that winds the cable unwound from the drum, and corrects the bending of the cable while in the pipeline. May be pushed into. However, spot welding is used to join the straight pipe (first protective pipe), so this part has low mechanical strength and cannot be passed through a vendor. The bend is not corrected. Therefore, in the cable core, there exists an inflection part where the bending is not corrected between the central part housed in the heat insulation pipe and the tip part drawn out from the heat insulation pipe, and the tip part of the cable core is the heat insulation pipe. It will not be in a state of being drawn straight from. As a result, it is difficult to abut the cable core to the connection target to form the core connection portion, and the workability of the connection structure is deteriorated.

  The present invention has been made in view of the above circumstances, and one of its purposes is to cut the end of the heat insulating tube of the superconducting cable when constructing the connection structure after laying the superconducting cable. It is to provide a superconducting cable connection structure suitable for adjusting the length of the cable.

  Before describing the connection structure of the superconducting cable of the present invention, the superconducting cable which is the premise of the present invention and the end treatment of the superconducting cable after installation will be briefly described.

  In the present invention, the superconducting cable includes a cable core having a superconducting conductor, and a heat insulating tube that houses the cable core and forms a vacuum heat insulating space between the inner tube and the outer tube, and the length of the heat insulating tube is long. It is actually designed to be longer than the installation length. In addition, the superconducting cable is positioned for installation of the connection structure after laying, and the length of the heat insulating tube is adjusted by cutting the extra length longer than the actual laying length of the heat insulating tube. . And when constructing a connection structure, the vacuum insulation of the vacuum heat insulation space of a heat insulation pipe is performed in the laying site. The superconducting cable connection structure of the present invention will be described below.

  The superconducting cable connection structure of the present invention includes a cable core having a superconducting conductor, a heat insulating tube that houses the cable core and forms a vacuum heat insulating space between the inner tube and the outer tube, and an end of the cable core; A core connection unit for connecting the connection target. An end vacuum partition, a refrigerant container, a vacuum container, an inner vacuum port, and an outer vacuum port are provided. The end vacuum partition is coupled to the end of the heat insulating tube to form an inner vacuum space that communicates with the vacuum heat insulating space. The refrigerant container is attached to the end vacuum partition and houses the core connection part. The vacuum vessel is attached to the outer tube and forms an outer vacuum space outside the end vacuum partition and the refrigerant vessel. The inner vacuum port is provided in the end vacuum partition so as to protrude in the radial direction, and is accommodated in the outer vacuum space. The outer vacuum port is provided in the vacuum vessel.

  Here, in the superconducting cable before laying, the length of the heat insulating tube is longer than the actual laying length, and the heat insulating tube has an extra length portion. There is no shortage, and the length of the heat insulating tube can be adjusted by cutting and removing the extra length at the end of the heat insulating tube. For this reason, for example, when a superconducting cable is laid in a pipeline, the pipeline length can be roughly determined by simple measurement, so that the measurement time can be greatly shortened. As a result, the time required for designing the superconducting cable can be greatly reduced. The actual laying length is the laying length of the heat insulating pipe and the cable core that are required when actually laying, and is the length excluding the extra length portion.

  The construction of the connection structure of the present invention is to cut the end of the heat insulation pipe after laying the superconducting cable, adjust the length of the heat insulation pipe, and then connect the end vacuum partition to the end of the heat insulation pipe to form the inner vacuum space. The inner vacuum space communicating from the inner vacuum port to the vacuum heat insulation space is evacuated. Moreover, the core connection part which connects a cable core edge part and a connection object is formed, and the refrigerant | coolant container which accommodates this core connection part is attached to an edge part vacuum partition. Next, after evacuation of the vacuum insulation space and formation of the core connection portion, a vacuum vessel is attached to the outer tube, an outer vacuum space is formed outside the end vacuum partition and the refrigerant vessel housing, and the outer vacuum space is formed from the outer vacuum port Complete by evacuating. Here, the evacuation work of the inner vacuum space (vacuum heat insulation space) and the formation work of the core connection part can be performed in parallel, and the construction work period of the connection structure is shortened by performing in parallel. It is possible.

  After installing the superconducting cable, cut off the end of the heat insulation tube at the installation site and attach a sealing member to the end of the newly formed heat insulation tube to seal the vacuum heat insulation space. There is a difficult problem. According to the connection structure of the present invention, since the outer vacuum space is formed outside the end vacuum partition provided with the inner vacuum port, even if the airtightness of the inner vacuum space is reduced, the outer vacuum space is more airtight. Thus, the vacuum state of the vacuum heat insulating space is easily maintained, and the reliability is improved. Further, for example, even if the vacuum vessel is damaged for some reason and the vacuum state of the outer vacuum space is destroyed, the outer vacuum space and the inner vacuum space are partitioned by the end vacuum partition, so that the inner vacuum space (vacuum The airtightness of the insulation space) is maintained, so the reliability is high.

  Further, according to the connection structure of the present invention, the inner vacuum port is provided in the end vacuum partition coupled to the heat insulating tube end, and the vacuum heat insulating space is evacuated from the inner vacuum port. Therefore, the diameter of the inner vacuum port is not limited by the distance between the inner tube and the outer tube unlike the vacuum port provided at the end of the heat insulation tube of the conventional superconducting cable. It is possible to increase the diameter of the vacuum port (for example, 20 mm or more). As a result, the vacuum insulation space can be efficiently evacuated by the large-diameter vacuum port, and the number of vacuum ports can be reduced while maintaining the time required for the evacuation operation to the same level as before.

  By the way, when constructing the connection structure after laying the superconducting cable, for example, a section where the heat insulating pipe from the attachment position of the vacuum vessel to the wall surface of the manhole where the opening of the pipe is formed is exposed from the pipe (in FIG. 6) It is also conceivable to provide a vacuum port communicating with the vacuum heat insulating space on the outer peripheral surface of the outer tube in the Lpw section). In this case, in order to attach the vacuum port, it is necessary to secure a sufficient working space between the end surface of the vacuum vessel and the wall surface of the manhole in which the opening of the pipe line is formed, but the space in the manhole is narrow There is a possibility that a sufficient working space cannot be secured. In the connection structure of the present invention, since the inner vacuum port is located in the vacuum vessel, it is not necessary to secure a work space for attaching the vacuum port between the vacuum vessel and the wall surface of the manhole.

  As one form of the connection structure of this invention, providing the bellows extended and contracted in the axial direction of a heat insulation pipe | tube in the middle of an edge part vacuum partition is mentioned.

  When the connection structure of the superconducting cable is constructed and the transmission line is constructed, the refrigerant is circulated through the heat insulating pipe in which the cable core is housed, and the superconducting conductor is maintained in the superconducting state, and the superconducting cable is operated. At that time, the heat insulation tube may heat shrink in the axial direction, but by providing a bellows in the middle of the end vacuum partition, the axial deformation and displacement of the end vacuum partition due to the heat shrinkage of the heat insulation tube are absorbed. can do. Moreover, when constructing the connection structure, it is also possible to absorb the assembly tolerance in the axial direction of the end vacuum partition.

  As one form of the connection structure of the present invention, the end vacuum partition is an outer wall cylinder connected to the outer pipe, an inner wall cylinder arranged at an interval inside the outer pipe, and the inner wall cylinder and the inner wall cylinder. And a straight connection pipe connecting between the pipes.

  Usually, a corrugated pipe having flexibility is used as the inner pipe of the heat insulating pipe. Since the corrugated pipe is corrugated into a spiral shape, there is a problem that it is difficult to align the inner wall cylinder with respect to the inner pipe when the inner wall cylinder and the inner pipe are directly connected by welding. Therefore, a straight connecting pipe is interposed between the inner wall cylinder and the inner pipe, and the inner wall cylinder and the inner pipe are connected by welding via the connecting pipe, thereby aligning the inner wall cylinder. It is easy to perform and improves workability. Further, when the inner pipe and the connecting pipe have different thicknesses, the difference in heat capacity between the two becomes large, so that it is difficult to directly connect the two. Therefore, the thickness of the connecting pipe is preferably about the same as the thickness of the inner pipe, for example, 0.8 mm or more and 2 mm or less.

  Further, in the embodiment in which the connecting pipe is provided between the inner wall cylindrical body and the inner pipe, it is preferable to include a reinforcing member that abuts the outer peripheral surface of the connecting pipe and reinforces the shape of the connecting pipe.

  As described above, the thickness of the connecting pipe is preferably about the same as the thickness of the inner pipe. However, the thickness of the connecting pipe is thin, and the strength of the connecting pipe is reduced when the inner wall cylinder is welded to the connecting pipe. There is a risk that the shape of the connecting pipe is deformed. Therefore, the shape of the connecting pipe can be reinforced and corrected by arranging the reinforcing member so as to contact the outer peripheral surface of the connecting pipe.

  In the superconducting cable connection structure of the present invention, since the end vacuum bulkhead joined to the end of the heat insulating tube is present in the vacuum vessel, the outer vacuum space maintains airtightness even if the airtightness of the inner vacuum space is reduced. Therefore, the vacuum state of the vacuum heat insulating space can be easily maintained, and the reliability is high. In particular, it is suitable for adjusting the length of the heat insulating tube by cutting the end portion of the heat insulating tube when constructing the connection structure after laying the superconducting cable.

It is a schematic sectional drawing which shows an example of the structure of the superconducting cable used for the connection structure of this invention. It is a schematic sectional drawing which shows the front-end | tip part structure of a superconducting cable. It is a principal part expansion schematic half sectional view which shows the connection structure of the superconducting cable which concerns on Embodiment 1 of this invention. It is a principal part expansion schematic half sectional view which shows the connection structure of the superconducting cable which concerns on Embodiment 2 of this invention. It is a principal part expansion schematic half sectional view which shows the connection structure of the superconducting cable which concerns on the modification 1. FIG. It is the schematic for demonstrating the connection structure of the conventional superconducting cable.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Moreover, the same code | symbol is attached | subjected to the same member in the figure. Here, first, the structure of the superconducting cable before laying, which is the premise of the present invention, will be described with reference to FIGS. 1 and 2, and then the superconducting cable connection structure according to the embodiment of the present invention will be described with reference to FIGS. I will explain.

  The superconducting cable 10 shown in FIG. 1 has a structure in which three cable cores 1 are twisted together and accommodated in a heat insulating tube 2 at a time. The heat insulating pipe 2 is a double-corrugated corrugated pipe composed of an inner pipe 21 and an outer pipe 22, and a vacuum heat insulating space is formed between both the pipes 21 and 22, and this space is sealed at both ends. A sealing member for stopping is provided. An anticorrosion layer 25 is formed on the outer tube 22. Moreover, you may arrange | position heat insulating materials, such as a super insulation (brand name), in a vacuum heat insulation space.

  On the other hand, the cable core 1 has a structure in which a former 11, a superconducting conductor 12, an insulating layer 13, a shield layer 14, and a protective layer 15 are arranged in order from the center. The superconducting conductor 12 and the shield layer 14 are formed by winding a Bi2223 superconducting tape wire. The insulating layer 13 is formed by winding PPLP (registered trademark, Polypropylene Laminated Paper).

  FIG. 2 is a schematic view for explaining the tip structure of the superconducting cable before laying. In the tip portion structure of the superconducting cable, a pooling eye 5 is attached to the end portion of the superconducting cable 10, and the tip portion of the cable core 1 is drawn from the end portion of the heat insulating tube 2 at this end portion. The pooling eye is attached to both ends of the superconducting cable 10. In this example, only the former 11 at the tip end portion of the cable core 1 is shown, and the remaining tip end portion of the cable core drawn out from the heat insulating tube 2 and the central portion housed in the heat insulating tube are not shown. Only two of the three cable cores are illustrated.

  An inner connecting pipe 23 and an outer connecting pipe 24 are joined to each end of the inner pipe 21 and the outer pipe 22 of the heat insulating pipe 2 by welding all around, and the inner connecting pipe 23 and the outer connecting pipe 24 are joined. The opening of the annular space formed between the sealing member 20 and the sealing member 20 is sealed. Thereby, the vacuum heat insulation space is maintained in a sealed state. The sealing member 20 is provided with a temporary port 4 that communicates with the vacuum heat insulating space and protrudes in the axial direction of the heat insulating tube 2. A flexible tube 41 is attached to the temporary port 4.

  The pooling eye 5 includes a head 51 having a hole 50 for attaching a tow hook, and a cylindrical body 52 connected to the head 51. The body 52 houses a gripping metal 53 for gripping the former 11 exposed from the cable core 1 and a holding member 54 for fixing the gripping metal 53, and the holding member 54 is joined to the inner peripheral surface of the body 52. The connecting pipe 55 is fixed. Then, the cable core 1 and the pooling eye 5 are connected by gripping the tip of the former 11 with the gripping metal 53 and fixing the gripping metal 53 to the holding member 54.

  On the other hand, a first protective tube (straight tube) 45 for protecting the temporary port 4 is joined to the sealing member 20 disposed at the end of the heat insulating tube 2, and further, at the end of the first protective tube 45, A second protective tube (corrugated tube) 46 for protecting the tip of the cable core 1 exposed from the heat insulating tube 2 is joined. Then, by joining the connecting pipe 55 attached to the pooling eye 5 (body 52) to the end of the second protective pipe 46, the heat insulating pipe 2 and the pooling eye 5 are connected to the first protective pipe 45, the first The two protective tubes 46 and the connecting tube 55 are connected.

  The vacuum heat insulating space of the heat insulating tube 2 is sealed in a state where moisture is removed, for example, by baking. Also, unlike the vacuum port provided at the end of the heat insulation tube of the conventional superconducting cable, the temporary port 4 does not need to be pulled out from the vacuum vessel after the construction of the connection structure, and compared to the conventional vacuum port. And short. The length of the temporary port 4 is, for example, about 50 mm to 150 mm, particularly about 50 mm to 100 mm. The length of the first protective tube 45 is designed to be a length (about 50 mm to 150 mm) corresponding to the length of the temporary port 4.

  Here, one of the features of the superconducting cable 10 used in the connection structure of the present invention is that the length of the heat insulating tube 2 is designed to be longer than the actual installation length, and at least one end portion thereof from the tip of the cable core 1 The distance Dci to the end of the heat insulating tube 2 is shorter than before. That is, an extra length portion is provided at at least one end of the heat insulating tube 2. Therefore, the distance Dpi from the tip of the pooling eye 5 to the end of the heat insulating tube 2 is also shorter than before. As a result, it is possible to solve the above-mentioned problems “problem of the cable tip protruding from the outer shape of the drum” and “problem in which the cable tip is bent at the installed cable”, and winding the drum and forming the core connection portion. Easy.

  The distance Dci from the tip of the cable core to the end of the heat insulating tube is, for example, 2000 mm or less, more preferably 1000 mm or less, and particularly preferably 500 mm or less. In this example, the distance Dci is set to 250 mm and designed to be 100 mm or more. The reason why the distance Dci is set to 100 mm or more is to facilitate the work of attaching the gripping bracket 53 to the former 11 exposed from the cable core 1.

  Next, the procedure from the design and manufacture of the above-described superconducting cable to the installation of the superconducting cable in the pipeline will be described.

(Design and manufacture of superconducting cable)
First, before manufacturing a superconducting cable, the length of a pipe line for laying the superconducting cable is measured. In this example, after laying the superconducting cable, the length of the heat insulating tube is adjusted by cutting and removing the extra length at the end of the heat insulating tube. Therefore, the pipe length may be roughly determined by simple measurement, and the design length of the heat insulating pipe is determined so as to be appropriately longer than the actual installation length based on the measurement result. Furthermore, it is preferable to design the superconducting cable so that the distance from the tip of the cable core to the end of the heat insulating tube is within the above-described range at both ends of the superconducting cable, and to have extra length portions at both ends of the heat insulating tube. At this time, the cable core may be provided with a surplus portion, and the length of the cable core may be longer than the actual installation length.

  Next, a superconducting cable is manufactured based on the design of the cable core and the heat insulating tube. The heat insulation tube is baked to remove moisture in the vacuum heat insulation space. For example, the baking process is performed simultaneously with evacuation, that is, moisture is removed while evacuating. Since this baking process cannot be practically performed after the superconducting cable is laid, it must be performed before the laying. Further, after removing moisture and the like in the vacuum heat insulation space by baking and evacuation, the dry air in the vacuum heat insulation space may be replaced with a dry gas. By replacing the vacuum heat insulating space with a dry gas and sealing it in a positive pressure state, it is easy to prevent the outside air (moisture) from entering the vacuum heat insulating space and maintain the state where the water is removed. As the dry gas, dry inert gas such as nitrogen or argon, particularly nitrogen gas is suitable. And after removing the water | moisture content etc. of a vacuum heat insulation space, a vacuum heat insulation space is sealed. In this example, the vacuum insulation space is sealed by welding the inner connection tube and the outer connection tube to both ends of the heat insulation tube and attaching sealing members having temporary ports to both ends of the heat insulation tube.

  Next, a pooling eye 5 is attached to the end of the superconducting cable (see FIG. 2). When attaching the pooling eye 5, the gripping metal 53 is attached to the former 11 exposed at the tip of the cable core 1, and the gripping metal 53 is fixed to the holding member. Then, the first protective tube 45 is joined to the end of the heat insulating tube 2, and then the second protective tube 46 is joined to the end of the first protective tube 45, and then the pooling eye is joined to the end of the second protective tube 46. 5 connecting pipes 55 are joined. For example, since a large tension is applied to the end portion on the drawing side when a superconducting cable is laid, it is preferable that all the joints be welded all around. The pooling eye 5 is also attached to the end opposite to the drawing side of the superconducting cable. At this time, at the end opposite to the pull-in side, all the joints may be spot welded in consideration of removal after installation.

  After attaching the pooling eye, wind the superconducting cable around the drum. In this example, since there is an extra length portion at the end of the heat insulation pipe and the distance from the cable core tip to the heat insulation pipe end is short, the straight pipe (first tube) connected from the pooling eye tip to the end of the heat insulation pipe The distance to the protective tube is shorter than before. For this reason, unlike the conventional case, the cable tip portion is less likely to jump out of the outer shape of the drum, and the cable tip portion is easily accommodated in the drum outer shape. In addition, since the first protective tube that protects the temporary port is shorter than the first protective tube that protects the conventional vacuum port, the distance from the tip of the pooling eye to the straight tube is shorter, and the The winding property of is further improved.

(Construction of superconducting cable pipes)
Lay the superconducting cable in the pipeline. When laying the superconducting cable, for example, attach a pulling hook to the pooling eye, pull the cable and pull it into the pipeline, and on the payout side of the superconducting cable, pass the cable unwound from the drum through the bender. For example, it can be pushed into the pipeline while correcting the bending. Here, when there is a surplus part only at one end of the heat insulation pipe, the length of the section where the heat insulation pipe after installation is exposed from the pipe line is strictly controlled for the other end as in the conventional case. (± 50mm) is required. On the other hand, when there are extra lengths at both ends of the heat insulation pipe, it is not necessary to strictly manage the length of the section where the heat insulation pipe after the installation is exposed from the pipe line, improving the installation workability of the superconducting cable To do.

  In this example, since the distance from the cable core tip to the end of the heat insulation tube is short, even if the bend is not corrected in the portion of the cable core corresponding to the location of the straight tube (first protective tube), it is compared with the conventional case. Thus, the end portion of the cable core is pulled out almost straight from the heat insulating tube. Moreover, since the 1st protection tube which protects a temporary port is short compared with the 1st protection tube which protects the conventional vacuum port, the bending which arises in a cable core front-end | tip part can be suppressed more.

  After laying the superconducting cable, the pooling eye, the first protective tube, and the second protective tube attached to both ends of the superconducting cable (the pulling side end and the opposite end) are removed.

(Superconducting cable connection structure)
After laying the superconducting cable, construct the connection structure. Hereinafter, a superconducting cable connection structure according to an embodiment of the present invention will be described.

<Embodiment 1>
The superconducting cable connection structure 3a according to the first embodiment shown in FIG. 3 includes a core connecting portion that connects an end portion of a cable core and a connection target, an end vacuum partition 6, a refrigerant vessel 31, and a vacuum vessel 32. The inner vacuum port 65 and the outer vacuum port 35 are provided.

  The end vacuum partition 6 is coupled to the end of the heat insulating tube 2 to form an inner vacuum space communicating with the vacuum heat insulating space. In this example, the end vacuum partition wall 6 includes a cylindrical inner wall cylinder 63 and a cylindrical outer wall cylinder 64 that is disposed outside the inner wall cylinder 63 with a space therebetween. At the end opposite to the heat insulating tube 2 side of the inner wall cylindrical body 63, there is a flange portion 63f protruding outward in the radial direction. A flange portion 32f is integrally formed at the end portion of the outer wall cylinder 64 on the heat insulating tube 2 side. The inner wall cylinder 63 and the outer wall cylinder 64 are combined together and joined to the end of the heat insulating tube 2 to form an inner vacuum space. Further, the diameter of the inner wall cylinder 63 is substantially the same as the diameter of the inner tube 21, and the diameter of the outer wall cylinder 64 is larger than the diameter of the outer tube 22.

  The refrigerant container 31 is attached to the end vacuum partition 6 and houses the core connecting portion 1j. The refrigerant container 31 is a cylindrical member that is half-broken in the radial direction.

  The vacuum vessel 32 is attached to the outer tube 22 and forms an outer vacuum space outside the end vacuum partition 6 and the refrigerant vessel 31. The vacuum vessel 32 includes a cylindrical portion 32p, and is configured by joining an end portion of the cylindrical portion 32p to a flange portion 32f. The cylindrical portion 32p is a cylindrical member that is half-broken in the radial direction. Further, the outer peripheral surface of the vacuum vessel 32 (cylindrical portion 32p) has a concave portion 32c protruding radially inward. The vacuum vessel 32 is subjected to anticorrosion treatment on the outer surface after the connection structure is constructed.

  End vacuum partition 6 (inner wall cylinder 63 and outer wall cylinder 64), refrigerant container 31 and vacuum container 32 are all made of stainless steel.

  The inner vacuum port 65 is provided on the outer peripheral surface of the end vacuum partition wall 6 (outer wall cylinder 64) so as to protrude in the radial direction, and communicates with the inner vacuum space. The inner vacuum port 65 is accommodated in the outer vacuum space. In this example, a seal-off valve having a diameter of 1 inch (25.4 mm) is used for the inner vacuum port 65. A plurality of inner vacuum ports 65 are provided in the circumferential direction of the outer wall cylinder 64.

  The outer vacuum port 35 is provided on the bottom surface of the recess 32c so as to be housed in the recess 32c of the vacuum vessel 32, and communicates with the outer vacuum space. In this example, a seal-off valve having a diameter of 1 inch (25.4 mm) is used for the outer vacuum port 35. A lid (not shown) is attached to the recess 32c of the vacuum container 32 so that the outer peripheral surface of the vacuum container 32 is flat. A plurality of outer vacuum ports 35 are provided in the circumferential direction of the vacuum vessel 32.

  Next, a procedure for constructing the connection structure 3a described above will be described.

(Construction of connection structure)
After laying the superconducting cable, adjust the length of the heat insulation pipe by cutting off the extra length at the end of the heat insulation pipe according to the construction position of the connection structure. At this time, outside air (moisture) to the vacuum heat insulation space is maintained by keeping the vacuum heat insulation space at a positive pressure while introducing the dry gas from the temporary port provided at the end opposite to the cut end of the heat insulation pipe. Can prevent intrusion. Moreover, the temporary port provided in the cutting | disconnection side edge part of a heat insulation pipe | tube is removed together when the extra length part of a heat insulation pipe | tube is cut | disconnected. In this example, the end of the heat insulating tube 2 is cut so that the outer tube 22 is shorter than the inner tube 21.

  After adjusting the length of the heat insulating tube, the end vacuum partition wall 6 is joined to the newly formed heat insulating tube end. In this example, first, a cylindrical pedestal 30 provided with a spiral groove on the inner peripheral surface is screwed into the outer peripheral surface of the outer tube 22 from the end of the outer tube, and the pedestal 30 is connected by welding. In addition, a straight connection pipe 61 is inserted from the tip of the cable core (not shown), and the connection pipe 61 is welded to the outer peripheral surface end of the inner pipe 21 so as to extend in the axial direction of the inner pipe 21. To do. The connecting pipe 61 is made of stainless steel and has a thickness of 0.8 mm which is substantially the same as the thickness of the inner pipe 21.

  Next, a cylindrical reinforcing member 62 that contacts the outer peripheral surface of the connecting pipe 61 is inserted, and the reinforcing member 62 is disposed on the outer peripheral surface of the connecting pipe 61. The reinforcing member 62 is made of FRP (fiber reinforced plastic) and reinforces and corrects the shape 61 of the connecting pipe. Further, the reinforcing member 62 has a step shape in which an end portion on the heat insulating tube 2 side comes into contact with the outer peripheral surface of the outer tube 22, and the step surface has a communication hole 62o communicating with the vacuum heat insulating space. Since the reinforcing member 62 has such a step shape, the deformation of the inner tube 61 and the outer tube 62 can be suppressed, and the opening of the vacuum heat insulating space can be held.

  Next, the inner wall cylinder 63 is inserted, and the inner wall cylinder 63 is welded to the end of the connection pipe 61 opposite to the heat insulating pipe 2 side. The end of the inner wall cylinder 63 connected to the connection pipe 61 is formed thin, and the thin end of the inner wall cylinder 63 and the end of the connection pipe 61 are connected by welding. The thickness of the inner wall cylinder 63 (excluding the thin end) is about 5 mm.

  Next, the outer wall cylinder 64 integrally formed with the flange portion 32f is inserted, the flange portion 32f is welded to the base 30, and the end of the outer wall cylinder 64 opposite to the flange portion 32f is connected to the inner wall cylinder 63. The flange portion 63f is welded. As a result, the end vacuum partition 6 is coupled to the end of the heat insulating tube 2 to form an inner vacuum space. The inner vacuum space and the vacuum heat insulation space communicate with each other through the communication hole 62o. The outer wall cylinder 64 is provided with an inner vacuum port 65, and a bellows fitting 64b extending and contracting in the axial direction of the heat insulating tube 2 is provided in the middle. The thickness of the outer wall cylinder 64 (excluding the bellows fitting) is about 5 mm.

After the end vacuum partition 6 is connected, the inner vacuum space 65 is evacuated from the inner vacuum port 65, and the vacuum heat insulating space communicating with the inner vacuum space is evacuated. Since the inner vacuum port 65 is provided after the laying of the superconducting cable, it can be positioned outside the inner diameter of the conduit, and there are few restrictions on the diameter and shape, and various shapes can be used. This evacuation is performed until the high vacuum state (degree of vacuum: 10 ⁻⁵ to 10 ⁻⁸ Pa) required for the operation of the superconducting cable. Since the moisture is removed when manufacturing the superconducting cable in the vacuum insulation space, when this evacuation is performed, moisture does not evaporate and the degree of vacuum does not decrease, and a predetermined high vacuum state is maintained for a short period of time. Can be achieved.

  In addition, a core connecting portion (not shown) that connects the end portion of the cable core drawn from the end portion of the heat insulating tube 2 and the connection target is formed. It is possible to carry out the evacuation work of the above-described vacuum heat insulation space and the formation work of the core connection portion in parallel. Since the formation of the core connection portion usually requires several weeks, there is sufficient time for evacuation to a predetermined high vacuum state.

  Here, when the cable core is also provided with an extra length portion, the extra length portion at the end of the cable core is cut. In this case, even if the tip of the cable core is not completely pulled out straight from the heat insulation tube, the cable core can be removed from the heat insulation tube by cutting the bent portion of the cable core tip. It becomes the state pulled out straight. Moreover, if the distance from the cable core tip to the heat insulation tube end is within the above-described range, the amount of cutting at the cable core end may be small. Furthermore, when cutting the extra length part of the cable core end, there are the following advantages.

  When manufacturing a superconducting cable, the end of the heat insulation tube is sealed, or welding work to attach the first protective tube or the second protective tube is performed. However, it is necessary to perform temperature management and scratch prevention measures to protect against damage. However, if the end portion of the cable core is cut, such management is unnecessary or easy, and the production of the superconducting cable can be simplified.

  After the formation of the core connection portion, the refrigerant container 31 is welded to the end portion of the end vacuum partition wall 6 (inner wall cylinder 63), and the core connection portion is accommodated in the refrigerant container 31.

  After completion of the vacuuming operation of the vacuum insulation space and the formation of the core connection part, the vacuum vessel 32 is attached to the outer tube 22 by welding and connecting the cylindrical part 32p to the flange part 32f welded to the base 30. An outer vacuum space is formed outside the end vacuum partition 6 and the refrigerant container 31. A hanger attachment part 32h is provided on the outer peripheral surface of the cylindrical part 32p. A hanger (not shown) such as an eyebolt is attached to the hanger attachment part 32h, and a hook is hooked on the hanger and a chain is attached. It is possible to work by lifting the cylindrical portion 32p with a block.

  Finally, by vacuuming the outer vacuum space from the outer vacuum port 35 to a predetermined degree of vacuum, the construction of the connection structure 3a is completed.

  The superconducting cable connection structure 3a according to the first embodiment has the following effects. Since the outer vacuum space and the inner vacuum space are partitioned by the end vacuum partition 6 in the vacuum vessel 32, the vacuum state of the vacuum heat insulating space is easily maintained and the reliability is high. Since the bellows fitting 64b is provided in the middle of the end vacuum bulkhead 6, it can absorb the axial deformation and displacement of the end vacuum bulkhead 6 due to thermal contraction of the heat insulating tube 2, and construct a connection structure. In this case, it is also possible to absorb the assembly tolerance in the axial direction of the end vacuum partition 6. Since the connecting pipe 61 is interposed between the inner wall cylindrical body 63 and the inner pipe 21, and the inner wall cylindrical body 63 and the inner pipe 21 are connected by welding via the connecting pipe 61, the inner wall cylindrical body with respect to the inner pipe 21 Easy to perform 63 connections. Furthermore, since the reinforcing member 62 is disposed so as to contact the outer peripheral surface of the connecting pipe 61, the shape of the connecting pipe 61 can be reinforced and corrected. Further, since the outer vacuum port 35 is housed in the recess 32c of the vacuum vessel 32 and the outer peripheral surface of the vacuum vessel 32 is flat, the outer surface of the vacuum vessel 32 can be easily subjected to anticorrosion treatment. It is possible to prevent problems such as being caught on clothes.

  In the connection structure 3a of the first embodiment, the case where the bellows fitting 64b is provided in the middle of the end vacuum partition 6 has been described as an example. However, the axial direction of the heat insulating tube 2 is also provided in the middle of the refrigerant container 31 or the vacuum container 32. A bellows that expands and contracts may be provided. By providing the bellows in the middle of the refrigerant container 31 or the vacuum container 32, it is possible to absorb the axial deformation and displacement of these members due to the thermal contraction of the heat insulating tube 2, and when constructing the connection structure, these members It is also possible to absorb the assembly tolerance in the axial direction.

<Embodiment 2>
The superconducting cable connection structure 3b according to the second embodiment shown in FIG. 4 is different from the connection structure 3a of the first embodiment shown in FIG. To do.

  In the connection structure 3b of the second embodiment, the end portion of the heat insulating tube 2 is cut so that the outer tube 22 is shorter than the inner tube 21 as compared to the connection structure 3a of the first embodiment. Thereby, the opening of the vacuum heat insulation space formed by the inner tube 61 and the outer tube 62 can be made larger, and the vacuum heat insulation space can be evacuated more efficiently. Further, in this example, the reinforcing member 62 only abuts on the outer peripheral surface of the connection pipe 61 and does not have a step shape.

<Modification 1>
In the connection structures 3a and 3b according to the first and second embodiments described above, the case where the inner vacuum port 65 is housed in the outer vacuum space has been described as an example. Among the inner vacuum ports provided in the end vacuum partition wall, , At least one may be replaced with a spare vacuum port.

  The superconducting cable connection structure 3c according to the first modification shown in FIG. 5 is an example in which one of the plurality of inner vacuum ports 65 provided in the connection structure 3a of the first embodiment is replaced with a spare vacuum port 70. This preliminary vacuum port 70 is provided so as to communicate with the inner vacuum space, penetrate the flange portion 32f of the vacuum vessel 32, and protrude in the axial direction of the vacuum vessel 32, and is drawn out of the vacuum vessel 32. It is. Specifically, the preliminary vacuum port 70 protrudes in the radial direction from the outer peripheral surface of the end vacuum partition wall 6 (outer wall cylinder 64), and is turned from the radial direction to the axial direction by the bent portion 71. Protrudes in the axial direction. A connection port 72 for connecting a vacuum monitor or a vacuum pump for measuring the degree of vacuum in the inner vacuum space (vacuum heat insulation space) is provided at the tip of the auxiliary vacuum port 70 protruding from the vacuum container 32, A cap 73 is attached to the connection port 72. Further, a storage box 75 for storing the front end portion of the auxiliary vacuum port 70 is fixed to the flange portion 32f of the vacuum vessel 32 with a bolt, and the front end portion of the auxiliary vacuum port 70 can be protected by the storage box 75. .

  In the connection structure 3c of the modified example 1, since the spare vacuum port 70 is provided, the vacuum degree of the vacuum heat insulation space is measured and confirmed with a vacuum monitor during operation of the superconducting cable, or the vacuum heat insulation is performed with a vacuum pump. The space can be evacuated to adjust the degree of vacuum. The spare vacuum port 70 is used for measuring and adjusting the degree of vacuum, so the diameter can be reduced compared to the inner vacuum port. In this example, the diameter is 15 mm, the same as the conventional vacuum port. Degree.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention.

  The superconducting cable connection structure of the present invention can be suitably used in the field of superconducting cables.

10 Superconducting cable
1 Cable core 1j Core connection
11 Former 12 Superconducting conductor 13 Insulating layer
14 Shield layer 15 Protective layer
2 Insulated tube 20 Sealing material
21 Inner tube 22 Outer tube 25 Anticorrosion layer
23 Inner connection tube 24 Outer connection tube
3,3a, 3b, 3c Connection structure
30 Base 31 Refrigerant container 32 Vacuum container
32p cylindrical part 32f flange part
32c Concave part 32h Hanging attachment part
35 Outer vacuum port
4 Temporary port 41 Flexible tube
45 First protection tube 46 Second protection tube
5 Pooling eye 50 holes
51 Head 52 Torso
53 Holding bracket 54 Holding member 55 Connection pipe
6 End vacuum bulkhead
61 Connecting pipe 62 Reinforcing member
62o communication hole
63 Inner wall cylinder 64 Outer wall cylinder
63f Flange 64b Bellows bracket
65 Inner vacuum port
70 Vacuum port for spare
71 Bending part 72 Connection port 73 Cap
75 storage box
M Manhole T pipeline

Claims (4)

A cable core having a superconducting conductor, a heat insulating tube that houses the cable core and forms a vacuum heat insulating space between the inner tube and the outer tube, and a core connecting portion that connects the end of the cable core and a connection target A superconducting cable connection structure comprising:
An end vacuum partition that is coupled to an end of the heat insulating tube and forms an inner vacuum space communicating with the vacuum heat insulating space;
A refrigerant container attached to the end vacuum partition and containing the core connection;
A vacuum vessel attached to the outer tube and forming an outer vacuum space outside the end vacuum partition and the refrigerant vessel;
An inner vacuum port provided in the end vacuum partition so as to protrude in the radial direction, and housed in the outer vacuum space;
A superconducting cable connection structure comprising: an outer vacuum port provided in the vacuum vessel.   The superconducting cable connection structure according to claim 1, further comprising a bellows extending and contracting in an axial direction of the heat insulating tube in the middle of the end vacuum partition. The end vacuum bulkhead,
An outer wall cylinder connected to the outer tube;
An inner wall cylinder disposed at an interval inside the outer tube;
The superconducting cable connection structure according to claim 1, further comprising a straight connection pipe that connects the inner wall cylindrical body and the inner pipe.   The superconducting cable connection structure according to claim 3, further comprising a reinforcing member that abuts on an outer peripheral surface of the connection pipe and reinforces a shape of the connection pipe.

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