JP5847000B2 - Cryogenic cable termination connection - Google Patents

Description

  The present invention relates to a termination connection part of a cryogenic cable for transmitting electric power.

  The superconducting cable system includes a reservoir tank, a pump, and a refrigerator for cooling the superconducting cable. The superconducting cable system is divided into a superconducting cable part and a superconducting terminal connection part. The superconducting cable part cools the superconducting cable and energizes it. This structure includes a superconducting cable and a refrigerant tank for holding liquid refrigerant and a vacuum layer for reducing heat intrusion into the refrigerant tank. The liquid refrigerant is supplied and adjusted by a reservoir tank, a pump, and a refrigerator attached to the superconducting terminal connection.

The end connection is electrically connected to a superconducting cable maintained at an extremely low temperature (at a temperature of -196 ° C at atmospheric pressure when liquid nitrogen is used as a refrigerant), and is connected to a lead conductor drawn out to a room temperature environment and a superconducting cable. A refrigerant tank that communicates with the heat insulating pipe and is filled with the refrigerant, and a soot pipe that accommodates the lead conductor drawn out of the refrigerant tank and forms a room temperature layer.
A liquid refrigerant layer and a gas refrigerant layer are formed in the refrigerant tank, and the lead conductor is drawn from the liquid refrigerant layer through the gas refrigerant layer to the room temperature layer in the soot tube.
An insulating structure made of a stress cone made of ethylene propylene rubber or epoxy or a capacitor cone is formed around the lead conductor.
The soot pipe is filled with an insulating fluid such as insulating oil, and a seal is disposed between the refrigerant tank and the soot pipe so as to prevent gas refrigerant from entering the gas so as to be kept airtight.

By the way, when the insulating structure applied to the lead conductor is, for example, a capacitor cone type bushing, it is designed to withstand insulation by inserting a metal foil inside and sharing the voltage. Electric field stress concentrates at the edge of the foil.
On the other hand, in the refrigerant tank, the dielectric constant is greatly different between liquid and gas in an insulating material such as nitrogen, so that the withstand voltage stress is reduced at the boundary between the liquid and gas.
In addition, since the withstand voltage stress of gas (excluding insulating gas such as SF6) is generally low, the periphery of the metal foil edge during bushing is a liquid refrigerant (for example, liquid nitrogen) or insulating oil with high withstand voltage stress. There is a need. For this reason, the liquid surface position in the refrigerant tank is required to be maintained at a position sufficiently higher than the tip of the metal foil positioned at the highest position among the plurality of metal foils on the liquid surface side during bushing. It was.

However, since the gas refrigerant layer in the refrigerant tank is adjacent to the normal temperature layer through the lead conductor, it is susceptible to heat intrusion, and there is heat exchange between the interface of the liquid refrigerant layer and the gas refrigerant layer, and accompanying a pressure change Since the state changes such as vaporization and aggregation are repeated intermittently, it is difficult to keep the liquid surface position constant. As described above, the conventional terminal connection portion changes the volume due to heat exchange by reducing the volume of the gas refrigerant layer by minimizing the gap between the lead conductor and the insulating structure formed around the lead conductor and the inner wall of the refrigerant tank. It has been proposed to reduce the amount and reduce the change in the liquid surface position (see, for example, Patent Document 1).
As another conventional technique, in a non-circulating cooling system, as a method of managing the liquid level (for example, a current limiting device), a triple structure including a refrigerant tank, a secondary refrigerant tank, and a vacuum heat insulating layer is provided from the inside. The refrigerant tank which has is sometimes used.

JP 2005-117724 A

  However, in the termination device described in Patent Document 1, in order to reduce the volume of the gas refrigerant layer, the gap between the lead conductor and the insulating structure formed around it and the inner wall of the refrigerant tank is minimized. There has been a problem that dielectric breakdown is likely to occur between the lead conductor and the inner wall surface of the refrigerant layer.

  A superconducting cable cooling system requires sufficient insulation performance. The superconducting cable cooling system is a system equipped with a reservoir tank, pump, and refrigerator, but it is difficult to maintain the pressure and liquid level of the gas layer with the condenser cone type bushing. The gas layer pressure has a lower limit necessary to obtain the required insulation capacity. As the refrigerant pressure rises, the refrigerant temperature also rises. On the other hand, if the refrigerant pressure is near atmospheric pressure, accidentally generated bubbles remain in the cable, resulting in an electrical weak point (that is, a pressure at which no bubbles are generated). That needs to be the case) As a condition that satisfies both, the refrigerant pressure is optimally around 0.2 MPaG. The upper limit is the design pressure of the container. On the other hand, the liquid level has a lower limit for maintaining the performance of the bushing (for example, a position sufficiently higher than the tip of the metal foil on the liquid level side during the above-described bushing) and an upper limit for obtaining a sufficient thermal gradient. . In conventional systems, the influence of Joule heat due to solar radiation and energization is so great that it is difficult to follow up only by managing the system.

An example is a change and control method of pressure and refrigerant liquid level position in a conventional system. In the conventional system, when the gas layer pressure reaches the set upper limit value, the heater switch in the reservoir tank is turned off to reduce the pressure in the reservoir tank, and the liquid refrigerant in the refrigerant tank is collected on the reservoir tank side, and the refrigerant tank side is recovered. Reduce pressure. When the pressure reaches the set lower limit value, the heater switch is turned on to vaporize the liquid refrigerant in the reservoir tank, the pressure is increased, the liquid refrigerant in the reservoir tank is sent to the refrigerant tank side, and the pressure on the refrigerant tank side is increased. Raise.
Alternatively, when the refrigerant liquid level position reaches the set upper limit value, the heater switch in the reservoir tank is turned off to reduce the pressure in the reservoir tank, and the liquid refrigerant in the refrigerant tank is collected on the reservoir tank side and the refrigerant liquid on the refrigerant tank side is recovered. Reduce the surface position. When the coolant level reaches the set lower limit value, the heater switch is turned on to vaporize the liquid refrigerant in the reservoir tank, and the pressure is increased to send the liquid refrigerant in the reservoir tank to the refrigerant tank side. The refrigerant liquid level is raised. Here, the set upper limit value and the set lower limit value are set in anticipation of fluctuations in the pressure or refrigerant liquid level position associated with turning on / off of the heater. In either case, the pressure P and the refrigerant liquid level position L are adjusted so as to fall within the control value only by turning the heater on and off. However, since the relationship between the pressure P and the refrigerant liquid surface position L varies depending on the state of the cooling system, one-to-one correspondence is impossible.

In the conventional system, a control method when the influence of Joule heat is large within a short time due to solar radiation or energization is taken as an example. The behavior when the pressure and the liquid level position are controlled only by turning on / off the heater switch in the reservoir tank is shown in FIGS. In the example of FIG. 7, a first set upper limit value P1 and a first set lower limit value P2 are determined for the pressure in the refrigerant tank, and when a rise in pressure is detected up to the first set upper limit value P1, the heater switch is turned off. When a pressure drop is detected up to the first set lower limit P2, control for turning on the heater switch is performed.
Moreover, in the example of FIG. 9, when the 1st setting upper limit H1 and the 1st setting lower limit H2 are defined about the liquid level height in a refrigerant tank, and the raise of a liquid level is detected to the 1st setting upper limit H1, When the heater switch is turned off and a drop in the liquid level is detected up to the first set lower limit value H2, the heater switch is turned on.
However, the pressure and the liquid level position change due to heat penetration are very large, and the refrigerant liquid level position cannot be sufficiently controlled only by turning the heater on and off. Therefore, in order to cope with this, the control shown in FIGS. 8 and 10 is performed. In the example shown in FIG. 8, a second setting upper limit value P3 that is higher than the first setting upper limit value P1 and a second setting lower limit value P4 that is lower than the first setting lower limit value P2 are newly determined, and the first setting is performed. When an increase in pressure is detected to the second set upper limit value P3 after the heater switch is turned off at the upper limit value P1, control is performed to release the gaseous refrigerant in the refrigerant tank to the outside, and the first set lower limit value is set. When a pressure drop is further detected to the second set lower limit value P4 after the heater switch is turned on at P2, control for replenishing the liquid refrigerant into the refrigerant tank is performed.
Further, in the example shown in FIG. 10, a second setting upper limit value H3 that is higher than the first setting upper limit value H1 and a second setting lower limit value H4 that is lower than the first setting lower limit value H2 are newly determined. When the rise of the liquid level is further detected up to the second set upper limit value H3 after the heater switch is turned off at the first set upper limit value H1, control is performed to release the gaseous refrigerant in the refrigerant tank to the outside. When the lowering of the liquid level is further detected to the second set lower limit value H4 after the heater switch is turned on at the set lower limit value H2, control for replenishing the liquid refrigerant into the refrigerant tank is performed.
Thereby, the liquid surface position is maintained in the case where the influence of Joule heat is large within a short time due to solar radiation or energization.
However, this method has a problem in that a facility for discharging the gas from the heater and the gas refrigerant layer and further a facility for replenishing the refrigerant are essential for the refrigerant tank.

Further, when necessary, in the conventional cooling system, a pressure adjusting mechanism for adjusting the pressure of the gas refrigerant layer is provided in the upper part of the refrigerant tank. This pressure adjustment mechanism consists of a discharge pipe with a double heat insulation structure with a vacuum layer, and a constant pressure valve that opens the valve to release gaseous refrigerant into the atmosphere when the refrigerant tank reaches a predetermined pressure. The pressure in the refrigerant tank is also adjusted by this pressure adjustment mechanism.
However, since the pressure adjusting mechanism is configured to release the refrigerant into the atmosphere when the pressure in the refrigerant tank rises, the refrigerant in the refrigerant tank is reduced. For this reason, when trying to avoid an increase in the pressure of the gas refrigerant layer in the refrigerant tank by the pressure adjusting mechanism, there is a problem that the loss of the refrigerant in the refrigerant tank becomes severe.

In addition, the prior art using a triple-layer refrigerant tank is to prevent the refrigerant from evaporating from the refrigerant tank, so that the liquid surface position of the secondary refrigerant tank is variable, As the liquid level position of the refrigerant tank changes, the degree of cooling of the gas refrigerant in the refrigerant tank changes, and there is a disadvantage that it is not suitable for controlling the liquid level position on the refrigerant tank side.
It is an object of the present invention to provide a terminal connection portion that can manage the liquid level position by turning on and off the heater even when the temperature fluctuation of the refrigerant is large, and that does not require forced discharge of the refrigerant or replenishment of the liquid refrigerant. Objective.

  The invention according to claim 1 is a terminal connection portion of a cryogenic cable including a cable core and a heat insulating tube that houses a liquid refrigerant that cools the cable core, the liquid refrigerant being stored, and a liquid refrigerant layer A refrigerant tank in which a gas refrigerant layer is formed and a lower end portion thereof are connected to the superconducting conductor layer of the cryogenic cable and are immersed in the liquid refrigerant layer, and an upper end portion is drawn out to the room temperature portion through the gas refrigerant layer. A lead conductor; an insulating member provided around the lead conductor; a first circulation cooling facility having a reservoir tank for storing liquid refrigerant to be supplied to the refrigerant tank; and the refrigerant tank. An auxiliary cooling mechanism having a heat exchange surface for exchanging heat with respect to the liquid refrigerant and the gas refrigerant at the liquid level position of the liquid refrigerant, and a second circulating cooling connected to the auxiliary cooling mechanism The liquid level in the refrigerant tank is within a target range by switching between heating and stopping of the heater that heats the reservoir tank according to the pressure or liquid level in the refrigerant tank. It is controlled.

  The invention according to claim 2 has the same configuration as that of the invention according to claim 1, and the auxiliary cooling mechanism is for auxiliary cooling for cooling the inside of the refrigerant tank through a partition wall having the heat exchange surface. As a circulation region of the liquid refrigerant, an auxiliary refrigerant tank formed around the refrigerant tank is provided, and a liquid surface position of the liquid refrigerant layer of the refrigerant tank is disposed between the upper end and the lower end of the auxiliary refrigerant tank. It is characterized by that.

  The invention described in claim 3 has the same configuration as that of the invention described in claim 1 or 2, and the auxiliary refrigerant tank is filled with liquid refrigerant and does not have a gas refrigerant layer.

  The invention according to claim 4 has the same configuration as that of the invention according to claim 2 or 3, and the second circulating cooling facility is configured to supply liquid refrigerant for auxiliary cooling from an upper part of the auxiliary refrigerant tank. The recovery of the liquid refrigerant for auxiliary cooling from the lower part of the auxiliary refrigerant tank is performed through a transport pipe.

  The invention according to claim 5 has the same configuration as that of the invention according to claim 2 or 3, and the second circulating cooling facility is configured to supply liquid refrigerant for auxiliary cooling from a lower part of the auxiliary refrigerant tank. The liquid refrigerant for auxiliary cooling from the upper part of the auxiliary refrigerant tank is collected through a transport pipe.

  The invention according to claim 6 has the same configuration as that of the invention according to any one of claims 2 to 5, and further divides the auxiliary refrigerant tank into a plurality of compartments arranged vertically, and each compartment is divided. On the other hand, the liquid refrigerant for auxiliary cooling is supplied and the liquid refrigerant for auxiliary cooling is collected.

  The invention according to claim 7 has the same configuration as that of the invention according to any one of claims 2 to 4, and the auxiliary refrigerant tank is an auxiliary formed around the refrigerant storage area of the refrigerant tank. It consists of a refrigerant tank, and the auxiliary refrigerant tank is formed from the lower side to the upper side of the liquid level of the liquid refrigerant layer of the refrigerant tank.

  The invention according to claim 8 has the same configuration as that of the invention according to any one of claims 1 to 7, and the second circulating cooling facility is a reservoir tank that stores liquid refrigerant for auxiliary cooling. And a circulation pump that circulates the liquid refrigerant for auxiliary cooling and a refrigerator that cools the liquid refrigerant for auxiliary cooling.

The present invention relates to an auxiliary cooling mechanism having a heat exchange surface for exchanging heat with respect to the liquid refrigerant and the gas refrigerant at the liquid surface position of the liquid refrigerant in the refrigerant tank, and the terminal connection portion connected to the auxiliary cooling mechanism. And a second circulating cooling facility.
For this reason, the liquid surface that performs heat exchange between the liquid refrigerant and the gas refrigerant in the refrigerant tank can be directly cooled, and a constant temperature range is maintained even if heat intrudes into the gas refrigerant layer in the refrigerant tank. It becomes possible. As a result, the heater can be turned off to suppress the pressure rise and fall of the gas refrigerant layer, and the liquid level of the liquid refrigerant in the refrigerant tank can be controlled.
Further, unlike the prior art, it is not necessary to bring the lead conductor and the inner wall surface of the refrigerant tank close to each other, and it is possible to effectively avoid the occurrence of dielectric breakdown between them.
Furthermore, it is possible to control the liquid level of the liquid refrigerant in the refrigerant tank without requiring the refrigerant tank to be equipped with a gas refrigerant discharge facility or a refrigerant replenishment facility in the constant operation.
Further, the auxiliary cooling mechanism has a structure having a heat exchange surface for exchanging heat with respect to the liquid refrigerant and the gas refrigerant at the liquid surface level of the liquid refrigerant in the refrigerant tank, and has a gas layer in the auxiliary cooling tank. In the case where the configuration is filled with only the liquid refrigerant, the conventional liquid level management of the secondary cooling tank is unnecessary, and the configuration advantageous for the liquid level management of the cooling tank can be achieved.

It is a figure which shows schematic structure of the termination | terminus connection part of the superconducting cable which concerns on 1st embodiment. It is a figure which shows an example of the superconducting cable by which a termination | terminus connection part is constructed. It is explanatory drawing which showed typically the cross-section of a capacitor | condenser cone. It is a figure which shows schematic structure of the termination | terminus connection part of the superconducting cable which concerns on 2nd embodiment. It is a figure which shows schematic structure of the termination | terminus connection part of the superconducting cable which is 3rd embodiment. It is explanatory drawing which illustrated the installation position in the case of equip | installing a baffle board inside the refrigerant tank of a termination | terminus connection part. It is a diagram which shows the example which controls the internal pressure of a refrigerant tank only with a heater. It is a diagram which shows the example which controls the internal pressure of a refrigerant tank by the heater and the external discharge | release of a gaseous refrigerant. It is a diagram which shows the example which controls the liquid level height of a refrigerant tank only with a heater. It is a diagram which shows the example which controls the liquid level height of a refrigerant tank by a heater and the external discharge | release of a gaseous refrigerant.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a termination connecting portion 1 of a superconducting cable 10 as a cryogenic cable according to the first embodiment, and FIG. 2 is a diagram showing an example of a superconducting cable on which the termination connecting portion 1 is constructed. .

(Superconducting cable)
A superconducting cable 10 shown in FIG. 2 is a single-core superconducting cable in which a single cable core 11 is housed in a heat insulating tube 12. The cable core 11 includes a former 111, a superconducting conductor layer 112, an electrical insulating layer 113, a superconducting shield layer 114, a normal conducting shield layer 115, a protective layer 116, and the like.

  The former 111 is a winding core for forming the cable core 11, and is formed by twisting together normal conductive wires such as copper wires. In the former 111, an accident current flowing in the superconducting conductor layer 112 in the event of a short circuit accident is shunted.

The superconducting conductor layer 112 is formed by spirally winding a plurality of superconducting wires on the former 111. In FIG. 2, the superconducting conductor layer 112 has a four-layer structure. A power transmission current flows through superconducting conductor layer 112 during steady operation.
The superconducting wire constituting the superconducting conductor layer 112 has, for example, a laminated structure in which an intermediate layer, a superconducting layer, a protective layer, and the like are sequentially formed on a tape-like substrate. The superconductor constituting the superconducting layer includes an RE-based superconductor (RE: rare earth element) exhibiting superconducting characteristics at a liquid nitrogen temperature or higher, for example, Y-based superconductivity represented by (composition formula) YBa ₂ Cu ₃ O _7-δ The body can be applied. Further, it may be a tape-shaped superconducting wire in which a superconductor is formed in a metal matrix. As the superconductor, a bismuth-based superconductor, for example, the chemical formula Bi ₂ Sr ₂ CaCu ₂ O _{8 + δ} (Bi2212), Bi ₂ Sr ₂ Ca ₂ Cu ₃ O _{10 + δ} (Bi2223) can be applied. In the chemical formula, δ represents an oxygen nonstoichiometric amount.

  The electrical insulating layer 113 is made of, for example, insulating paper, semi-synthetic paper in which insulating paper and polypropylene film are joined, a polymer nonwoven fabric tape, and the like, and is formed by winding on the superconducting conductor layer 112.

  Superconducting shield layer 114 is formed by spirally winding a plurality of superconducting wires on electrical insulating layer 113. In FIG. 2, the superconducting shield layer 114 has a two-layer structure. In the superconducting shield layer 114, substantially the same current as the conductor current flows in reverse phase by electromagnetic induction during steady operation. The superconducting wire constituting the superconducting shield layer 114 can be the same as the superconducting conductor layer 112.

The normal conductive shield layer 115 is formed by winding a normal conductive conductor represented by a copper wire or a copper braided wire on the superconductive shield layer 114. The normal conducting shield layer 115 is shunted with an accident current flowing in the superconducting shield layer 114 in the event of a short circuit accident.
The protective layer 116 is made of, for example, insulating paper, polymer nonwoven fabric, or the like, and is formed by winding on the normal conductive shield layer 115.

The heat insulating tube 12 has a double ring structure including an inner tube 121 that houses the cable core 11 and is filled with a refrigerant (for example, liquid nitrogen), and an outer tube 122 that is disposed so as to cover the outer periphery of the inner tube 121. Have.
The inner tube 121 and the outer tube 122 are, for example, stainless corrugated tubes. Between the inner tube 121 and the outer tube 122, for example, a multilayer heat insulating layer 123 made of a laminate of polyethylene films deposited with aluminum is interposed, and kept in a vacuum state (so-called super insulation). Further, the outer periphery of the outer tube 122 is covered with an anticorrosion layer 124 such as polyethylene.

(Outline of termination connection)
As shown in FIG. 1, the end connection portion 1 is configured such that the end portion of the superconducting cable 10 is accommodated in the cryogenic container 20 in a predetermined state, and current is drawn to the actual system side via the lead conductor 31. .
In the termination connection portion 1, the superconducting conductor layer 112 of the superconducting cable 10 and the lead conductor 31 are electrically connected via a conductor movable connection terminal 50 as a conductor connection terminal.

(Cryogenic container)
The cryogenic container 20 is made of SUS (stainless steel) and has a double structure including an inner refrigerant tank 21 and an outer vacuum tank 22, and the end of the superconducting cable 10 is connected thereto. The vacuum vessel 22 is connected to the outer tube 122 of the heat insulating tube 12 of the superconducting cable 10 by welding, and the refrigerant vessel 21 is connected to the inner tube 121 by welding. And the area | region between the hollow refrigerant tank 21 and the vacuum tank 22 and the area | region between the inner tube | pipe 121 and the outer tube | pipe 122 of the heat insulation pipe | tube 12 are each vacuum-sucked, and the heat insulation structure is formed.

The internal region of the refrigerant tank 21 and the internal region of the inner pipe 121 communicate with each other, and these regions are filled with a liquid refrigerant (for example, liquid nitrogen). This liquid refrigerant is circulated from the inner pipe 121 to the refrigerant tank 21 by a first circulation cooling facility 80 described later.
The first circulation cooling facility 80 includes a reservoir tank 85 for storing liquid refrigerant, a circulation pump 86 for circulating the liquid refrigerant, a cooling device 81 including a refrigerator 87 for cooling the liquid refrigerant, the refrigerant tank 21 and the internal Transport pipes 82 and 83 that form a circulation path of the liquid refrigerant between the pipe 121 and the cooling device 81, and a flow rate control valve 84 that is provided in the transport pipe 82 and serves as a flow rate adjusting mechanism that freely controls the flow rate of the liquid refrigerant. And.
The transport pipes 82 and 83 are both insulated by a double pipe structure having a vacuum layer. The transport pipe 82 is connected to the refrigerant tank 21 via a bayonet connector 88 having a heat insulating structure, and supplies the liquid refrigerant from the cooling device 81 to the refrigerant tank 21. The transport pipe 83 is connected to the inner pipe 121 of the superconducting cable 10 via a bayonet connector 89 having a heat insulating structure, and recovers the liquid refrigerant from the inner pipe 121 toward the cooling device 81.
As a result, the liquid refrigerant is cooled to a predetermined cryogenic temperature by the refrigerator 87 provided outside the terminal connection portion 1, and is circulated so that the liquid refrigerant is contained in the terminal connection portion 1 and the superconducting cable 10. Exhaust heat of the liquid refrigerant is performed.

Moreover, the cryogenic container 20 is formed in a cylindrical shape rising vertically upward, and a cylindrical insulator tube 33 concentric with the cryogenic container 20 is connected to the upper portion thereof. The upper metal fitting 32 connected to the real system side is attached to the upper end.
The refrigerant tank 21 of the cryogenic vessel 20 is filled with the liquid refrigerant as described above, and a liquid refrigerant layer made of liquid nitrogen is formed below the liquid surface S of the liquid refrigerant. A gas refrigerant layer made of gaseous nitrogen is formed on the upper side of the substrate.

Inside the refrigerant tank 21 and the insulator tube 33 and at the center positions thereof, a lead conductor 31 that electrically connects the conductive movable connection terminal 50 to the upper metal fitting 32 is disposed. The lead conductor 31 is a solid or hollow round bar made entirely of a good conductor, for example, copper.
The lead conductor 31 is equipped with a capacitor cone type bushing 41 as an insulating member so as to surround the lead conductor 31. The bushing 41 is attached to the upper end portion of the cryogenic container 20 by an attaching flange portion 411 fixedly provided on the outer periphery. The flange portion 411 for attaching the bushing 41 is sealed so as to seal the refrigerant tank 21, thereby separating the respective internal regions of the refrigerant tank 21 and the insulator tube 33, so that liquid or gas Is blocked.
The inner region of the insulator tube 33 is filled with a fluid insulator made of insulating oil, SF ₆ gas, or the like. Note that the fluid insulator in the insulator tube 33 is at room temperature, and the insulator tube 33 corresponds to an ordinary temperature part.

(Condenser cone)
FIG. 3 is an explanatory view schematically showing a cross-sectional structure of the bushing 41. As shown in FIGS. 1 and 3, the bushing 41 includes a stainless steel hollow pipe 412 into which the lead conductor 31 is inserted, a bushing insulator 414 made of an insulating material formed on the outer peripheral surface of the hollow pipe 412, and a drawer. A collar 413 made of an insulating material inserted in a connecting portion between the conductor 31 and the hollow pipe 412, and a mounting flange portion 411 provided on the outer peripheral surface of the bushing insulator 414 and provided at an intermediate position in the vertical direction. ing.

  The bushing insulator 414 includes a lower end portion 414a, an intermediate portion 414b, and an upper end portion 414c in the vertical direction. The intermediate portion 414b has a uniform outer diameter in the vertical direction, and the lower end portion 414a and the upper end portion 414c are The diameter of the bushing insulator 414 is reduced toward the lower side or the upper side, and the entire bushing insulator 414 is formed in a substantially spindle shape.

  A metal foil 415 that forms a capacitor electrode having a constant width in the vertical direction is formed on the lower end 414a and the upper end 414c of the bushing insulator 414 in a stepwise manner at a constant interval in the radial direction around the hollow pipe 412. And it is embedded in the insulator 414 so as to be concentric. The outermost metal foil 415 is formed over the entire area of the intermediate portion 414b of the bushing insulator 414, and the outermost metal foil 415 is attached to a ground wire (not shown) and grounded. Yes.

As the bushing insulator 414, epoxy resin, EPR (ethylene propylene rubber), rubber, FRP (fiber reinforced plastics), or the like is used. The metal foil 415 is formed of, for example, an aluminum foil or a copper wire, a copper braided wire, a metal wire, a metal braided wire, or the like.
With this structure, each metal foil 415 has a shape in which capacitors having the same capacity are connected in series from the high voltage side (center side) to the low voltage side (outer peripheral side) in the bushing insulator 414. The electric field along the interface of the insulator 414 is arranged almost uniformly. Further, since the outermost metal foil 415 of the bushing insulator 414 is grounded, the surface electric field at the intermediate portion where the outer diameter of the bushing insulator 414 is uniform can be set to the ground potential.

(Auxiliary cooling mechanism)
By the way, the bushing 41 extends from the lower end portion to the upper end portion thereof from the liquid refrigerant layer of the refrigerant tank 21 to the normal temperature portion in the insulator tube 33 through the gas refrigerant layer.
The metal foil 415 is concentrically embedded in the lower end portion 414a of the bushing 41, and the lower end portion of the metal foil 415 has a high electric field strength due to its structure. Further, the electric field concentrates on the liquid level S of the refrigerant in the refrigerant tank 21 due to the difference in dielectric constant between liquid and gas.
For this reason, the liquid surface S of the liquid refrigerant in the refrigerant tank 21 is a region where the lower end portion of the metal foil 415 exists (bushing 41) so that dielectric breakdown does not occur between the liquid surface and the lower end portion of the metal foil 415. It is necessary to manage the position that is separated from the lower end portion 414a by a certain amount upward as a lower limit position so as not to descend from this position.
In the refrigerant tank 21, the gas refrigerant layer is likely to undergo a heat change and is also close to the normal temperature portion, so that the temperature is likely to rise. As a result, the vaporization of the refrigerant proceeds by heat exchange at the liquid level, and the gas refrigerant layer The increase in pressure is a major factor that causes the liquid level of the liquid refrigerant in the refrigerant tank 21 to drop.

For this reason, in order to perform appropriate liquid level management, the auxiliary cooling mechanism 60 is provided in the refrigerant tank 21.
The auxiliary cooling mechanism 60 is inside the vacuum chamber 22 and circulates the liquid refrigerant for auxiliary cooling provided via the partition wall 61 having the heat exchange surface 61a for the liquid refrigerant and the gas refrigerant in the refrigerant tank 21. It is comprised by the auxiliary | assistant refrigerant | coolant tank 62 which is an area | region.
The auxiliary refrigerant tank 62 has a cylindrical shape surrounding the refrigerant tank 21 and is physically separated from the refrigerant tank 21 so that refrigerant does not flow. And the circulation of the liquid refrigerant for auxiliary cooling may be performed in a separate system from the liquid refrigerant in the refrigerant tank 21. The liquid refrigerant for auxiliary cooling uses the same liquid nitrogen as the liquid refrigerant in the refrigerant tank 21, but in the case of a separate system, another liquid or gas refrigerant having a temperature lower than that of liquid nitrogen may be used.

  External heat intrusion to the entire system is W1, steady-state heat intrusion is W1, abnormal (for example, overcurrent occurrence) or non-steady heat intrusion (summer daytime, etc.) W2, refrigerant through the auxiliary cooling mechanism If the allowable maximum value per unit time of the amount of heat discharged from the tank is Wmax, an auxiliary cooling mechanism that satisfies W2 <Wmax (W1 <W2) may be used.

The partition wall 61 may use the inner wall of the SUS (stainless steel) refrigerant tank 21 as it is, but only the auxiliary refrigerant tank 62 may be formed of a material having higher thermal conductivity. However, the liquid refrigerant and the gas refrigerant in the refrigerant tank 21 are formed so as to surround the entire circumference, and the liquid refrigerant in the auxiliary refrigerant tank 62 is a liquid and gas refrigerant in the refrigerant tank 21 through the single partition wall 61. Is supposed to cool.
That is, the inner surface side of the partition wall 61 is a heat exchange surface 61 a between the auxiliary cooling liquid refrigerant in the auxiliary cooling mechanism 60 and the liquid refrigerant and gas refrigerant in the refrigerant tank 21. And the auxiliary | assistant refrigerant | coolant tank 62 and its partition 61 are formed in the range containing the liquid level S of the liquid refrigerant | coolant in the refrigerant tank 21 about an up-down direction. That is, the position which is above the lower end of the metal foil 415 where the lower end is the uppermost position among the plurality of metal foils 415 of the bushing 41 by a distance that does not cause dielectric breakdown is below the liquid coolant level. Since it is a limit position, it is formed in a range including this lower limit position.

(Second circulation cooling facility)
The auxiliary cooling mechanism 60 is also provided with a second circulating cooling facility 70 that circulates and cools the liquid refrigerant in the auxiliary refrigerant tank 62.
The second circulation cooling facility 70 includes a reservoir tank 75 that stores liquid refrigerant for auxiliary cooling, a circulation pump 76 that circulates liquid refrigerant for auxiliary cooling, and a refrigerator 77 that cools the liquid refrigerant for auxiliary cooling. A cooling device 71, transport pipes 72 and 73 forming a circulation path of the liquid refrigerant between the auxiliary refrigerant tank 62 and the cooling device 71, and a flow rate which is provided in the transport pipe 72 and freely controls the flow rate of the liquid refrigerant. And a flow control valve 74 as an adjustment mechanism.

Each of the transport pipes 72 and 73 is heat-insulated by a double pipe structure having a vacuum layer, penetrates the vacuum tank 22 of the cryogenic container 20 and is provided inside the auxiliary refrigerant tank 62. It is connected to the. Further, the transport pipes 72 and 73 are connected to the outer wall of the vacuum chamber 22 via bayonet connectors 78 and 79 having a heat insulating structure, so that heat intrusion at the connection portion with the vacuum chamber 22 is prevented.
The transport pipe 72 is a supply pipe for supplying liquid refrigerant from the cooling device 71 to the auxiliary refrigerant tank 62, and communicates with an opening provided in the vicinity of the upper end portion of the auxiliary refrigerant tank 62. The transport pipe 73 is a recovery pipe for recovering the liquid refrigerant from the auxiliary refrigerant tank 62 to the cooling device 71 and communicates with an opening provided in the vicinity of the lower end portion of the auxiliary refrigerant tank 62.
Thereby, the liquid refrigerant cooled by the cooling device 71 is supplied to the upper part of the auxiliary refrigerant tank 62, and the liquid refrigerant in the auxiliary refrigerant tank 62 is recovered from the lower part of the auxiliary refrigerant tank 62. In the auxiliary refrigerant tank 62, the heated liquid refrigerant stays in the upper part and the low-temperature liquid refrigerant stays in the lower part, so the heated liquid refrigerant is immediately cooled, and the temperature of the liquid refrigerant in the auxiliary refrigerant tank 62 is increased and decreased. It is possible to make uniform over the range. Thereby, the auxiliary refrigerant tank 62 can effectively cool the liquid refrigerant and the gas refrigerant at the liquid surface position in the refrigerant tank 21.
The liquid refrigerant is more preferably supplied from the upper part of the auxiliary refrigerant tank 62 and recovered from the lower part, but the liquid refrigerant may be supplied from the lower part of the auxiliary refrigerant tank 62 and recovered from the upper part. In this case, it is possible to effectively recover the liquid refrigerant whose temperature has risen in the upper part of the auxiliary refrigerant tank 62 (the same applies to the second and third embodiments).

  Further, in the second circulating cooling facility 70, even when the liquid refrigerant is vaporized in the reservoir tank 75, the refrigerant gas does not move to the circulation pump 76 side, and only the liquid refrigerant passes through the circulation pump 76. 62 is supplied. As a result, the inside of the auxiliary refrigerant tank 62 is filled with the liquid refrigerant, and no gas refrigerant layer is generated therein, so that the refrigerant tank 21 can be cooled over its entire width. Yes.

  The flow control valve 74 is a valve whose opening can be adjusted by manual operation, and the flow rate of the liquid refrigerant from the cooling device 71 to the auxiliary refrigerant tank 62 can be controlled by adjusting the opening.

(Operation of terminal connection)
With regard to the terminal connection portion 1 having the above-described configuration, the operation of the auxiliary cooling mechanism 60 and the circulation cooling facility 70 will be described in particular.
In the superconducting cable 10 and the refrigerant tank 21 of the terminal connection portion 1, the liquid refrigerant is circulated by a circulation cooling device (not shown), and the cable core 11 of the superconducting cable 10 is cooled.
In the refrigerant tank 21, the gas refrigerant absorbs heat due to heat intrusion from above, etc., the liquid surface of the liquid refrigerant is evaporated and condensed, and the liquid surface height varies depending on the pressure of the gas refrigerant layer. It will be in a state to get.

(Pressure control and liquid level control)
Further, as shown in FIG. 1, the refrigerant tank 21 includes a liquid level sensor 131 (for example, a distance measuring sensor) serving as a liquid level detecting unit that detects the liquid level of the liquid refrigerant inside, and a refrigerant tank 21. A pressure sensor 132 as pressure detecting means for detecting the pressure of the internal gas layer is provided, and a heater 133 for heating the internal refrigerant is provided in the reservoir tank 85 of the first circulating cooling facility 80.
Then, by a control device (not shown), pressure control for maintaining the pressure in the refrigerant tank 21 in a certain range and liquid level control for maintaining the liquid level of the liquid refrigerant in the refrigerant tank 21 in a certain range. Executed.

That is, as shown in FIG. 7, the first set upper limit value P1 and the first set lower limit value P2 are determined in advance for the pressure in the refrigerant tank 21, and the pressure sensor 132 increases the pressure to the first set upper limit value P1. When detected, the switch of the heater 133 is turned off, the pressure in the reservoir tank 85 is reduced, the liquid refrigerant in the refrigerant tank 21 is collected on the reservoir tank 85 side, and the pressure on the refrigerant tank 21 side is reduced.
When the pressure sensor 132 detects a decrease in pressure up to the first set lower limit value P2, the heater 133 is turned on, bubbles are generated in the liquid refrigerant in the reservoir tank 85, the pressure is increased, and the reservoir Control is performed to send the liquid refrigerant in the tank 85 to the refrigerant tank 21 side and increase the pressure on the refrigerant tank 21 side.

Further, as shown in FIG. 9, the first set upper limit value H1 and the first set lower limit value H2 are determined in advance for the liquid level in the refrigerant tank 21, and the liquid level sensor 131 reaches the first set upper limit value H1. When the rise in the liquid level is detected, the heater 133 is turned off, the pressure in the reservoir tank 85 is reduced, and the liquid refrigerant in the refrigerant tank 21 is collected on the reservoir tank 85 side, and the refrigerant liquid level on the refrigerant tank 21 side. Reduce position.
Further, when the liquid level sensor 131 detects a decrease in the liquid level to the first set lower limit value H2, a control for turning on the switch of the heater 133 is performed, and bubbles are generated in the liquid refrigerant in the reservoir tank 85, Control is performed to raise the pressure and send the liquid refrigerant in the reservoir tank 85 to the refrigerant tank 21 side to raise the refrigerant liquid surface position on the refrigerant tank side.

  The pressure control and the liquid level control are performed simultaneously. For example, when it is detected that either the pressure control or the liquid level control should turn on the heater 133, the heater 133 is turned on. If either of the pressure control and the liquid level control detects that the heater 133 should be turned off, the heater 133 is turned off, and the mutual control is performed in parallel.

(Technical effects according to the first embodiment)
In the terminal end connection portion 1 in the first embodiment, the partition 61 having a heat exchange surface 61a for exchanging heat with respect to the liquid refrigerant and the gas refrigerant at the liquid surface position S of the liquid refrigerant in the refrigerant tank 21 is provided. And an auxiliary cooling mechanism 60 having a cylindrical auxiliary refrigerant tank 62 surrounding the refrigerant tank 21 and a second circulation cooling facility 70 for circulatingly cooling the liquid refrigerant in the auxiliary refrigerant tank 62. Further, the cooling device 71 of the circulation cooling facility 70 includes a reservoir tank 75, a circulation pump 76, and a refrigerator 77.
For this reason, the liquid surface that performs heat exchange between the liquid refrigerant and the gas refrigerant in the refrigerant tank 21 can be directly cooled, and a certain temperature range even if the gas refrigerant layer in the refrigerant tank 21 receives heat intrusion. It becomes possible to keep it. Thereby, the pressure rise and fall of the gas refrigerant layer can be suppressed more effectively, and the height of the liquid level S of the liquid refrigerant in the refrigerant tank 21 can be controlled.
Further, by maintaining the height of the liquid refrigerant liquid level S in the refrigerant tank 21 by the auxiliary refrigerant tank 62 and the second circulating cooling equipment 70, the heater 133 is turned on to suppress the pressure rise and fall of the gas refrigerant layer. For example, pressure control and liquid level control for setting the stepwise upper and lower limit values shown in FIG. 8 and FIG. 10 described above are unnecessary, and the liquid level of the liquid refrigerant in the refrigerant tank 21 is reduced. It is possible to control appropriately.

  Further, the circulation cooling facility 70 of the auxiliary cooling mechanism 60 is supplied with liquid refrigerant from the upper part of the auxiliary refrigerant tank 62 by the transport pipe 72 and recovered from the lower part of the auxiliary refrigerant tank 62 by the transport pipe 73. The temperature gradient between the upper part and the lower part in the refrigerant tank 62 is eliminated, and the refrigerant tank 21 can be effectively cooled.

  In addition, an emergency pipe that includes a discharge pipe 341 provided with a heat insulating structure and a constant pressure valve 342 that discharges a gaseous refrigerant when the pressure of the discharge pipe 341 exceeds a certain value, and adjusts the pressure of the gaseous refrigerant layer unsteadyly. Since the pressure adjusting mechanism 34 is provided in the refrigerant tank 21 and the transport pipe 72 of the auxiliary refrigerant tank 62 is provided with the flow rate control valve 74 for adjusting the flow rate of the liquid refrigerant, the pressure of the gas refrigerant layer in the refrigerant tank 21 is kept constant. The gas refrigerant layer can be stabilized at a constant equilibrium temperature by adjusting the flow rate of the liquid refrigerant with respect to the auxiliary refrigerant tank 62 while being maintained within the range, and the liquid in the refrigerant tank 21 can be turned on by turning the heater 133 on and off. It is possible to arbitrarily adjust the surface position.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows a schematic configuration of a terminal connection portion 1A according to the second embodiment.
In the termination connection unit 1A according to the following embodiment, the same components as those of the termination connection unit 1 described above are denoted by the same reference numerals and redundant description is omitted, and the termination connection unit 1A is the same as that of the termination connection unit 1A. Only the differences will be explained.

The auxiliary cooling mechanism 60A of the terminal connection portion 1A is different from the terminal connection portion 1 in that an auxiliary cooling pipe 62A formed in a spiral shape in the refrigerant tank 21 is provided as a circulation region of liquid refrigerant for auxiliary cooling. .
That is, the auxiliary cooling pipe 62A is substantially cylindrical by being wound up and down without any gap, and is arranged so as to surround the liquid refrigerant and the gaseous refrigerant in the refrigerant tank 21.
The formation range of the auxiliary cooling pipe 62 </ b> A in the vertical direction is the same as that of the auxiliary refrigerant tank 62 described above. That is, it is a range including the liquid level S of the liquid refrigerant in the refrigerant tank 21, with respect to the lower end portion of the metal foil 415 that is the uppermost position among the liquid surface side ends of the plurality of metal foils 415 of the bushing 41. Thus, it is formed in a range including a position that is above a distance that does not cause dielectric breakdown.

  The auxiliary cooling pipe 62A is made of SUS, copper, or other material having good thermal conductivity. At the site where the auxiliary cooling pipe 62A is formed, the inner wall of the refrigerant tank 21 is removed, and half of the inner wall surface of the auxiliary cooling pipe 62A in the spiral state is a partition wall having a heat exchange surface. Further, because of this structure, the auxiliary cooling pipes 62A adjacent to each other in a spiral state are sealed by welding or the like so that no gaps are formed between the pipe walls.

  Further, the transport pipe 72 of the second circulating cooling facility 70 is connected to the upper end of the auxiliary cooling pipe 62A, and the transport pipe 73 is connected to the lower end of the auxiliary cooling pipe 62A. Thereby, liquid refrigerant is supplied to the auxiliary cooling pipe 62A from its upper end, and liquid refrigerant is recovered from its lower end.

In the case of the terminal connection portion 1A including the auxiliary cooling pipe 62A, the second circulation including the reservoir tank 75, the circulation pump 76, and the refrigerator 77 is provided for the auxiliary cooling pipe 62A, as in the case of the terminal connection portion 1. Since the cooling of the liquid refrigerant is performed at a constant flow rate by the cooling facility 70, it is possible to cool the liquid refrigerant and the gas refrigerant on the liquid surface where heat exchange is performed in the refrigerant tank 21.
Moreover, since the refrigerant can be circulated along the inside of the auxiliary cooling pipe 62A by providing the spiral auxiliary cooling pipe 62A, it is effective in the circumferential direction with respect to the liquid refrigerant and the gas refrigerant in the refrigerant tank 21. It is possible to efficiently and uniformly cool, and to efficiently perform cooling and liquid level adjustment.
Further, by maintaining the height of the liquid refrigerant liquid level S in the refrigerant tank 21 by the auxiliary cooling pipe 62A and the second circulating cooling facility 70, the heater 133 is turned on to suppress the pressure rise and fall of the gas refrigerant layer. For example, pressure control and liquid level control for setting the stepwise upper and lower limit values shown in FIG. 8 and FIG. 10 described above are unnecessary, and the liquid level of the liquid refrigerant in the refrigerant tank 21 is reduced. It is possible to control appropriately.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram showing a schematic configuration of the terminal connection portion 1B of the superconducting cable 10 as the cryogenic cable according to the third embodiment.
In the termination connection unit 1B according to the following embodiment, the description of the same configuration as the termination connection unit 1 is omitted with the same reference numerals omitted, and the termination connection unit 1B is different from the termination connection unit 1. The point will be explained exclusively.

  The end connection portion 1B includes the same low-temperature container 20 and auxiliary cooling mechanism 60 as the end connection portion 1, and a first liquid refrigerant is circulated through the refrigerant tank 21 of the low-temperature container 20 and the inner pipe 121 of the superconducting cable 10. The point is that the circulating cooling facility 80B and the second circulating cooling facility 70B that circulates the liquid refrigerant in the auxiliary cooling mechanism 60 share the reservoir tank 75B that stores the liquid refrigerant.

The first circulation cooling facility 80B includes a reservoir tank 75B for storing liquid refrigerant, a circulation pump 86 for circulating the liquid refrigerant, and a cooling device 81 including a refrigerator 87 for cooling the liquid refrigerant, the refrigerant tank 21, and the inner pipe. 121 and the cooling device 81, transport pipes 82 and 83 that form a circulation path of the liquid refrigerant, and a flow control valve 84 that is provided in the transport pipe 82 and serves as a flow rate adjusting mechanism that freely controls the flow rate of the liquid refrigerant; It has.
The transport pipes 82 and 83 are both insulated by a double pipe structure having a vacuum layer. The transport pipe 82 is connected to the refrigerant tank 21 via a bayonet connector 88 having a heat insulating structure, and supplies the liquid refrigerant from the cooling device 81 to the refrigerant tank 21. The transport pipe 83 is connected to the inner pipe 121 of the superconducting cable 10 via a bayonet connector 89 having a heat insulating structure, and recovers the liquid refrigerant from the inner pipe 121 toward the cooling device 81.

The second circulating cooling facility 70B includes a reservoir tank 75B for storing liquid refrigerant, a circulation pump 76B for circulating the liquid refrigerant, a cooling device 71B including a refrigerator 77B for cooling the liquid refrigerant, an auxiliary refrigerant tank 62, and a cooling device. Transport pipes 72B and 73B that form a circulation path of the liquid refrigerant with the apparatus 71B, and a flow rate control valve 74B that is provided in the transport pipe 72B and serves as a flow rate adjustment mechanism that freely controls the flow rate of the liquid refrigerant. Yes.
The transport pipes 72B and 73B are both heat-insulated by a double pipe structure having a vacuum layer. The transport pipe 72B is connected to the auxiliary refrigerant tank 62 via a bayonet connector 78B having a heat insulating structure, and supplies the liquid refrigerant from the cooling device 71B to the auxiliary refrigerant tank 62. Further, the transport pipe 73B is connected to the auxiliary refrigerant tank 62 via a bayonet connector 79B having a heat insulating structure, and recovers the liquid refrigerant from the auxiliary refrigerant tank 62 toward the cooling device 71B.

As described above, since the cooling device 81 of the first circulating cooling facility 80B and the cooling device 71B of the second circulating cooling facility 70B share the reservoir tank 75B, the same liquid refrigerant circulates through each path. Become.
Thereby, the configuration of each of the circulating cooling facilities 80B and 70B is simplified, and it is possible to reduce the installation cost and the manufacturing cost and reduce the heat intrusion.

  Further, a downstream portion of the transport pipe 72B from the flow control valve 74B and a downstream portion of the transport pipe 82 from the flow control valve 84 are connected by a connecting pipe 91, and the connecting pipe 91 has a flow control. A valve 92 is provided. Therefore, even when a sudden trouble occurs in either one of the cooling device 81 and the cooling device 71B and stops, the cooling tank 21 and the auxiliary cooling tank 62 can be opened and closed by appropriately opening and closing the flow control valves 74B, 84, and 92. It is possible to supply the liquid refrigerant to both of them.

  The reservoir tank 75B is equipped with a heater 133 that heats the internal liquid refrigerant, the pressure adjustment mechanism 34 is equipped with a pressure sensor 132 that detects the internal pressure of the refrigerant tank 21, and the refrigerant tank. 21 is equipped with a liquid level sensor 131 for detecting the liquid level of the internal liquid refrigerant. Thereby, the pressure control and the liquid level control shown in FIGS. 7 and 9 are executed.

  In addition, it is good also as a structure provided with the helical auxiliary | assistant cooling pipe 62A illustrated in 2nd embodiment instead of the auxiliary | assistant refrigerant | coolant tank 62 also in the termination | terminus connection part 1B.

(Other)
As mentioned above, although the invention made | formed by this inventor was concretely demonstrated based on 1st-3rd embodiment, this invention is not limited to said each embodiment, In the range which does not deviate from the summary. It can be changed.

  For example, although the case where the superconducting conductor cable 10 is a single-core type superconducting cable is illustrated, in the terminal connection part constructed at the terminal part of the three-core collective superconducting cable in which the three-core cable cores are collectively stored in the heat insulation pipe Is also applicable.

Moreover, although the superconducting cable 10 was illustrated as a cryogenic cable, each said embodiment is applicable also to the other cryogenic cable used under cryogenic temperature.
Moreover, in each embodiment, the temperature of the refrigerant | coolant which flows through each circulation cooling system which cools a secondary refrigerant tank and a refrigerant tank may be fundamentally the same. That is, it is not necessary to circulate the refrigerant in the secondary cooling tank at a relatively low temperature relative to the refrigerant tank. Basically, it may be below the control temperature level.

In addition, the refrigerant tank 21 may be equipped with a baffle plate that bisects the inner region. FIG. 6 is an explanatory diagram illustrating the installation positions B1 to B3 when the baffle plate is installed inside the refrigerant tank 21 of the end connection portion 1 described above.
The baffle plate is a porous flat plate made of plastic or other insulator, and has heat insulation properties.
The baffle plate has a lead conductor 31 and a bushing 41 passing through the center thereof. Further, by providing a slight gap between the baffle plate and the surface of the bushing 41 and between the baffle plate and the inner wall of the refrigerant tank 21, heat insulation between the upper and lower sides of the baffle plate can be ensured.
The baffle plate is fixed by a method such as hanging from the flange portion 411 of the bushing 41 or the upper lid.
Moreover, the installation position of the baffle plate may be arranged so as to be fixed above the liquid level S and the gas refrigerant layer is divided into two vertically as shown by B1 in FIG. Moreover, it is good also as arrangement | positioning which fixes to the height of the liquid level S substantially, and isolate | separates a gas refrigerant layer and a liquid refrigerant tank like B2 of FIG. Furthermore, it is good also as arrangement | positioning which fixes below a liquid level S and divides a liquid refrigerant layer into two up and down like B3 of FIG. Since the baffle plate has a porous structure, the specific gravity is small, and buoyancy may be generated to fix the baffle plate below the liquid level S in this way. It is desirable to support with a member.
Further, the baffle plate needs to be installed in the range from the upper end to the lower end of the auxiliary refrigerant tank 62 in the vertical direction.
Since the baffle plate is porous, it has high heat insulating properties. Therefore, by fixing the baffle plate as described above, it is possible to prevent the intrusion heat on the upper side of the baffle plate from moving to the lower region and to obtain a high cooling effect. Is possible.
In addition, since the baffle plate does not have air permeability and water permeability, a minute ventilation hole penetrating vertically is formed so that the pressure sensor 132 does not affect the pressure detection of the gas layer of the refrigerant tank 21. It may be.
Further, when the baffle plate is arranged at B1 or B2, a liquid level gauge that measures the height of the float can be used to detect the liquid level of the liquid refrigerant inside the refrigerant tank 21. It is. In this case, a small through hole for moving the float up and down is formed in the baffle plate so as not to prevent the vertical movement of the liquid level gauge.
Moreover, although the case where the baffle plate was provided in the termination connection part 1 was illustrated, you may provide in the termination connection parts 1A and 1B.

Further, the cylindrical auxiliary refrigerant tank 62 of the auxiliary cooling mechanism 60 may be divided into a plurality (for example, two to three) in the vertical direction by a horizontal dividing surface. For example, when dividing into three, the auxiliary refrigerant tank 62 is divided into three regions of an upper stage, a middle stage, and a lower stage, and each inside is partitioned with water tightness so that the liquid refrigerant tank cannot be circulated. . Then, a transport pipe 72 that supplies the liquid refrigerant into the compartment and a transport pipe 73 that collects the liquid refrigerant in the compartment are individually connected to each of the upper, middle, and lower three compartments, and the liquid refrigerant is individually provided for each compartment. It is possible to circulate.
Thus, depending on which of the three regions corresponding to the upper, middle, and lower sections of the heat exchange surface 61 a of the partition wall 61 is in the height of the liquid refrigerant S in the refrigerant tank 21. Thus, it is possible to locally cool efficiently by supplying a liquid refrigerant and circulating the corresponding compartment.
Further, when the degree of increase in the internal pressure of the refrigerant tank 21 and the degree of decrease in the liquid level are severe, it is possible to circulate the liquid refrigerant to all the compartments to increase the cooling capacity.
In addition, the flow control valve 74 provided in the transport pipe 72 of each section is an electromagnetic valve capable of controlling the flow rate and opening / closing by an electric signal, and the liquid refrigerant is circulated to the corresponding section according to the detection of the liquid level S. It is good also as a structure which performs automatic control to perform. Also in this case, when the rate of increase in pressure or the rate of increase in liquid level is obtained and the value exceeds a certain value, control may be added to perform circulation for all the compartments.

1,1A, 1B Termination connection 10 Superconducting cable (Cryogenic cable)
11 Cable core 12 Heat insulation pipe 20 Cryogenic container 21 Refrigerant tank 22 Vacuum tank 31 Drawer conductor 33 Insulator pipe (normal temperature part)
34 Pressure adjusting mechanism 35 Metal foil 41 Capacitor cone type bushing (insulating member)
50 Conductive connection terminals 60, 60A Auxiliary cooling mechanism 61 Partition wall 61a Heat exchange surface 62 Auxiliary refrigerant tank (circulation region of liquid refrigerant for auxiliary cooling)
62A Auxiliary cooling pipe (circulation region of liquid refrigerant for auxiliary cooling)
70, 70B Circulation cooling equipment 71 Cooling device 72, 72B Transport pipe 73, 73B Transport pipe 74, 74B Flow rate control valve (flow rate adjustment mechanism)
75, 75B Reservoir tanks 80, 80B First circulating cooling equipment 85 Reservoir tank 111 Former 112 Superconducting conductor layer 113 Electrical insulation layer 114 Superconducting shield layer 121 Inner pipe 122 Outer pipe 133 Heater 341 Discharge pipe 342 Constant pressure valve 414 Bushing insulator 414a Lower end 414b Middle portion 414c Upper end 415 Metal foil S Liquid level

Claims (8)

A terminal connection part of a cryogenic cable comprising a cable core and a heat insulating pipe for containing a liquid refrigerant for cooling the cable core,
A refrigerant tank in which the liquid refrigerant is stored and a liquid refrigerant layer and a gas refrigerant layer are formed;
A lower conductor is connected to the superconducting conductor layer of the cryogenic cable and is immersed in the liquid refrigerant layer, and an upper conductor is drawn out to the room temperature part through the gas refrigerant layer,
An insulating member provided around the lead conductor;
A first circulating cooling facility having a reservoir tank for storing liquid refrigerant to be supplied to the refrigerant tank;
An auxiliary cooling mechanism provided in the refrigerant tank and having a heat exchange surface for exchanging heat with respect to the liquid refrigerant and the gas refrigerant at a liquid surface position of the liquid refrigerant in the refrigerant tank;
A second circulating cooling facility connected to the auxiliary cooling mechanism,
According to the pressure in the refrigerant tank or the liquid level, the liquid level in the refrigerant tank is controlled within a target range by switching between heating and stopping of the heater that heats the reservoir tank. Characteristic cryogenic cable termination connection. The auxiliary cooling mechanism includes an auxiliary refrigerant tank formed around the refrigerant tank as a circulation region of liquid refrigerant for auxiliary cooling for cooling the inside of the refrigerant tank through a partition having the heat exchange surface. ,
The terminal connection part of the cryogenic cable according to claim 1, wherein a liquid level position of a liquid refrigerant layer of the refrigerant tank is disposed between an upper end and a lower end of the auxiliary refrigerant tank.   The terminal connection part of a cryogenic cable according to claim 2, wherein the auxiliary refrigerant tank is filled with a liquid refrigerant and does not have a gas refrigerant layer.   The second circulating cooling facility performs a supply of liquid refrigerant for auxiliary cooling from the upper part of the auxiliary refrigerant tank and recovery of liquid refrigerant for auxiliary cooling from the lower part of the auxiliary refrigerant tank through a transport pipe. The terminal connection part of the cryogenic cable according to claim 2 or 3, characterized by the above-mentioned.   The second circulation cooling facility performs supply of liquid refrigerant for auxiliary cooling from the lower part of the auxiliary refrigerant tank and recovery of liquid refrigerant for auxiliary cooling from the upper part of the auxiliary refrigerant tank through a transport pipe. The terminal connection part of the cryogenic cable according to claim 2 or 3, characterized by the above-mentioned.   3. The auxiliary refrigerant tank is divided into a plurality of upper and lower sections, and supply of the auxiliary cooling liquid refrigerant and recovery of the auxiliary cooling liquid refrigerant are performed for each of the sections. The termination | terminus connection part of the cryogenic cable as described in any one of 1-5.   The terminal connection part for a cryogenic cable according to any one of claims 2 to 6, wherein the auxiliary refrigerant tank includes an auxiliary cooling pipe formed in a spiral shape inside the refrigerant tank.   The second circulation cooling facility includes a reservoir tank that stores liquid refrigerant for auxiliary cooling, a circulation pump that circulates liquid refrigerant for auxiliary cooling, and a refrigerator that cools liquid refrigerant for auxiliary cooling. The terminal connection part of the cryogenic cable as described in any one of Claim 1 to 7 characterized by the above-mentioned.

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