JP5091419B2 - Superconducting device - Google Patents

Description

  The present invention relates to a superconducting device applied to a superconducting current limiting device or the like for suppressing a short-circuit current flowing in a system to a predetermined value or less when connected to an electric power system, and more particularly, a superconducting coil or superconducting cooled by a refrigerant. The present invention relates to a superconducting device having a superconductor such as an element.

  In recent years, superconducting technology capable of flowing a large current with zero electrical resistance has been developed, and development for various applications such as current application and industrial application has been promoted. In particular, since the appearance of high-temperature superconductivity in 1986, it is expected to be put to practical use at a liquid nitrogen temperature of 77.35K. Some superconducting applications such as transformers, power cables and current limiters have indeed been experimentally demonstrated as equipment at liquid nitrogen temperatures.

  FIG. 20 shows a conventional technique when a superconducting device having a superconducting coil or a superconducting element cooled by a refrigerant such as liquid nitrogen is used. As shown in FIG. 20, a superconductor 1 such as a superconducting coil or a superconducting element is cooled by being immersed in a refrigerant 2 such as liquid nitrogen. The refrigerant container 3 is disposed in a heat insulating container 5 installed at room temperature via a heat insulating space 4 such as a vacuum. The refrigerant container 3 is provided with a refrigerant injection pipe 7 and a discharge pipe 8, and these pipes 7 and 8 are respectively provided with flow rate adjusting valves 7 a and 8 a. In addition, a current lead 6 is provided to connect the superconducting coil 1 to a power source or power system arranged on the normal temperature side.

  Since superconducting application equipment to which such a configuration is applied generally uses a superconducting coil in a superconducting state, evaporation of the refrigerant is not a big problem. However, for example, when a current exceeding an assumed value flows for some reason and the superconducting state is broken, that is, when the normal conducting state occurs, the superconducting coil generates a large amount of heat, leading to evaporation of the refrigerant. Further, for example, in the case of a superconducting current limiting device that is connected to the power system and suppresses the short-circuit current flowing through the system at the time of an accident to a predetermined value or less, normal conduction is a phenomenon based on the original function, In that case, the refrigerant is released to the atmosphere. Therefore, maintenance for adding refrigerant for the next operation is required.

  Another problem arises when the outlet is closed and the container is sealed. That is, since the pressure rises by confining the evaporative gas in the container, a pressure-resistant configuration of the container is required, which leads to an increase in weight of the container. Moreover, since the thickness of the member which comprises a container is enlarged, the heat penetration | invasion to a refrigerant | coolant container increases. Furthermore, even when the discharge port is in an open state or a closed state, the bubble generation itself may be a problem due to a decrease in withstand voltage between the superconducting coil and the refrigerant container due to the bubble generation. Further, there is a possibility of a decrease in withstand voltage between turns and between layers in the superconducting coil.

For this reason, conventionally, a configuration has been proposed in which refrigerant cooling means is provided in a sealed container and pressure is increased in the sealed container to suppress generation of bubbles from the refrigerant (for example, see Patent Document 1). Further, a configuration has been proposed in which the space between the outer tub and the inner tub is evacuated, and the interior is provided with a refrigerant injecting section, a pressure adjusting section, a gas discharging section, a refrigeration apparatus, and a heat insulating section (see Patent Document 2, for example). .
JP-A-4-193024 Japanese Patent Laid-Open No. 2002-5552

  As described above, superconducting coils and superconducting elements cooled in a refrigerant such as liquid nitrogen have a problem of generation of bubbles due to a large amount of evaporating gas during the normal conducting transition. In particular, in the case of a resistance type superconducting fault current limiter, the refrigerant evaporates every time the current limiting operation, which is its function, and the following problems occur as the refrigerant evaporates.

  The first problem is that maintenance of the refrigerant resupply operation is required to compensate for the liquid level reduced by the refrigerant evaporation. This maintenance problem is not only complicated, but it is necessary to temporarily stop the current limiter operation so that the worker can approach the device during maintenance, and the current limiter is protected while the operation is stopped. There is also a problem that the power system and equipment are not protected. As in the prior art, sealing the container and confining the evaporative gas is one way to prevent the refrigerant from being discharged outside the container. However, in order to confine the evaporated refrigerant, it is necessary to increase the pressure resistance specification of the container. That is, it is necessary to increase the thickness of the container component (container wall). Since the container wall is connected from the room temperature portion to the low temperature portion, increasing the wall thickness increases heat penetration due to heat conduction from the room temperature end to the low temperature end. This is because heat penetration due to heat conduction is proportional to the cross-sectional area of the container wall, that is, the wall thickness of the container.

  A second problem is a decrease in withstand voltage due to bubble generation. In particular, liquid nitrogen is a good insulating medium, but the dielectric strength is significantly reduced by gasification. The resistance type current limiter is a device premised on the normal conduction transition of the superconducting wire, and the problem is that the dielectric strength is reduced and the dielectric breakdown is caused by gasification of the liquid during the normal conduction transition. Further, in the configuration in which the refrigerant is discharged to the outside of the container, the liquid level decreases every time the current limiting operation is performed, and the possibility of dielectric breakdown during the next current limiting operation is increased. If the container is designed based on the insulation characteristics in the gas state so that the inside of the container does not break down in a gas state and a sufficiently long insulation distance is secured, the problem of the breakdown is reduced. However, in this case, the size and weight of the apparatus are increased, and the specifications required by the user cannot be satisfied in terms of size.

  The present invention has been made in view of such circumstances, has a high bubble extinguishing function, can eliminate or greatly suppress refrigerant resupply, can reduce the thickness of the container components, and is insulated. It is an object of the present invention to provide a superconducting device that can prevent a decrease in proof stress, dielectric breakdown, and the like, and further achieve a compact configuration and weight reduction.

In order to achieve the above object, in the superconducting device according to the present invention, in the superconducting device in which the refrigerant is accommodated in a refrigerant container surrounded by a heat insulating container and the superconductor is cooled by immersing the superconductor in the refrigerant. Is provided with bubble extinguishing means for extinguishing bubbles generated by heat generation in the case of normal conduction, the bubble extinguishing means is a porous material disposed above the superconductor in the refrigerant in the refrigerant container, the refrigerant container The container has at least one means selected from a downwardly open container disposed above the superconductor in the refrigerant and a baffle plate disposed in the refrigerant to prevent the generated bubbles from rising.

  According to the present invention, the bubble extinguishing function is enhanced, the decrease in the refrigerant can be prevented or suppressed, the increase in the pressure in the container can be suppressed, the thickness of the container component can be decreased, the dielectric strength is reduced, and the insulation is reduced. It is possible to prevent breakage and the like, and further achieve effects such as a compact configuration and weight reduction.

  Hereinafter, embodiments of a superconducting device according to the present invention will be described with reference to FIGS.

[First Embodiment (FIG. 1)]
FIG. 1 is a longitudinal sectional view showing a superconducting device according to a first embodiment of the present invention. As shown in FIG. 1, in the present embodiment, a superconducting fault current limiter that houses a refrigerant 12 in a refrigerant container 13 surrounded by a heat insulating container 15 and immerses and cools the superconductor 11 in the refrigerant 12. Next, a description will be given of a configuration in which the bubble extinguishing means that extinguishes the bubbles a generated by heat generation when the superconductor 11 becomes normal conducting is a buffer container 20 connected to the outside of the refrigerant container 13 via a gas discharge pipe 18. . Here, the superconductor 11 indicates a superconducting coil or a superconducting element. In the present embodiment and the following embodiments, the superconductor 11 will be described as the superconducting coil 11.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. A space is provided between the refrigerant container 13 and the heat insulation container 15, and this space is formed as a heat insulation space 14 by vacuum or heat insulation filling. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  A sealed buffer container 20 is disposed outside the refrigerant container 13 as a means for eliminating bubbles, and the refrigerant container 13 and the buffer container 20 are connected via a gas discharge pipe 18. . That is, an opening (gas introduction port) 19a at one end of the gas discharge pipe 18 is inserted into the space above the refrigerant 12 in the refrigerant container 13, and a valve 18a as a throttle portion is provided in the middle of the gas discharge pipe 18. An opening (gas discharge port) 19 b at the other end of the gas discharge pipe 18 is provided in the buffer container 20.

  In such a configuration, when the refrigerant 12 evaporates in the refrigerant container 13 due to heat generation due to normal conduction of the superconducting coil 11 and bubbles a are generated along with this, the refrigerant 12 in the refrigerant container 13 It is released as gas into the upper space. This gas is introduced from an introduction port 19a at one end of the gas discharge pipe 18 and flows to the buffer container 20 side through a valve 18a serving as a throttle portion in the middle of the pipe due to a pressure difference. Is discharged into the buffer container 20 from the discharge port 19b.

  In this case, since the whole superconducting device including the refrigerant container 13 and the buffer container 20 is not opened to the atmosphere, the refrigerant 12 is confined in the apparatus without being released to the atmosphere. Since the internal space of the provided buffer container 20 functions as a buffer space having a constant capacity, an increase in pressure is suppressed in the refrigerant container 13.

  In addition, the pressure on the refrigerant container 13 side becomes higher than that on the buffer container 20 side due to the effect of pressure loss that occurs during gas flow, which is the effect of the throttle portion of the valve 18a. For this reason, as the bubble generation continues, the refrigerant temperature becomes lower than the saturation temperature determined by the pressure, and the bubble suppression effect appears.

  As described above, according to the present embodiment, the bubble disappearance function is enhanced, the decrease in the refrigerant can be prevented or suppressed, the increase in the pressure in the refrigerant container 13 can be suppressed, and the thickness of the container component can be reduced. In addition, it is possible to prevent a decrease in dielectric strength and dielectric breakdown. Furthermore, it is possible to reduce the size and weight of the configuration.

[Second Embodiment (FIG. 2)]
FIG. 2 is a longitudinal sectional view showing a superconducting device according to a second embodiment of the present invention. As shown in FIG. 2, in the present embodiment, a superconducting fault current limiter including a refrigerator 21 in a refrigerant container 13 as a second bubble extinguishing means will be described in addition to the configuration of the first embodiment described above. In addition, about the component which is common in 1st Embodiment, the code | symbol same as FIG. 1 is attached | subjected to FIG. 2, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 2, in this embodiment, the superconducting coil 11 is the same as the first embodiment in that it is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. In addition to this, a refrigerator 21 is provided in the refrigerant container 13. The refrigerator 21 is a cryogenic refrigerator, and includes, for example, a refrigerator head 21a mounted on the upper surface of the lid 15a, and a cooling stage 21b of the refrigerant head provided in a suspended state below the lid 15a. I have. And the cooling stage 21b is immersed in the refrigerant | coolant 12, and becomes a structure which can recool a refrigerant | coolant. For example, the refrigerator 21 is installed at a position obliquely upward from the superconducting coil 11 in the refrigerant container 13 and promotes convection of the refrigerant 12 in the refrigerant container 13 as indicated by an arrow b in FIG. It has become.

  In such a configuration, when the refrigerant 12 evaporates in the refrigerant container 13 due to heat generation due to normal conduction of the superconducting coil 11 and bubbles a are generated along with this, the refrigerant 12 in the refrigerant container 13 It is released as gas into the upper space. This gas is introduced from an introduction port 19a at one end of the gas discharge pipe 18 and flows to the buffer container 20 side through a valve 18a serving as a throttle portion in the middle of the pipe due to a pressure difference. Is discharged into the buffer container 20 from the discharge port 19b.

  In this case, since the whole superconducting device including the refrigerant container 13 and the buffer container 20 is not opened to the atmosphere, the refrigerant 12 is confined in the apparatus without being released to the atmosphere. Since the internal space of the provided buffer container 20 functions as a buffer space having a constant capacity, an increase in pressure is suppressed in the refrigerant container 13.

  In addition, the pressure on the refrigerant container 13 side becomes higher than that on the buffer container 20 side due to the effect of pressure loss that occurs during gas flow, which is the effect of the throttle portion of the valve 18a. For this reason, as the bubble generation continues, the refrigerant temperature becomes lower than the saturation temperature determined by the pressure, and the bubble suppression effect appears.

  Further, in the present embodiment, the refrigerant 12 can be recondensed by driving the refrigerator 21. Therefore, the bubble extinction function can be further enhanced, thereby eliminating the need for maintenance of the refrigerant resupply operation.

  Therefore, the decrease in the refrigerant can be prevented or suppressed more effectively, the increase in the pressure in the refrigerant container 13 can be suppressed, the thickness of the container components can be reduced, the dielectric strength can be reduced, and the dielectric breakdown can be prevented. Further, the effects of downsizing the configuration and weight reduction are further improved.

[Third Embodiment (FIG. 3)]
FIG. 3 is a longitudinal sectional view showing a superconducting device according to a third embodiment of the present invention. As shown in FIG. 3, in the present embodiment, the superconducting fault current limiter is configured to accommodate the refrigerant 12 in the refrigerant container 13 surrounded by the heat insulating container 15 and immerse the superconductor 11 in the refrigerant 12 to cool it. The configuration in which the bubble extinguishing means 22 for eliminating the bubbles a generated by the heat generation when the superconductor 11 becomes normal conducting is provided inside the refrigerant container 13 will be described.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. A space is provided between the refrigerant container 13 and the heat insulation container 15, and this space is formed as a heat insulation space 14 by vacuum or heat insulation filling. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  The bubble extinguishing means 22 provided inside the refrigerant container 13 is configured as a cover that covers the space above the superconducting coil 11 in the refrigerant 12 in the refrigerant container 13. The bubble extinguishing means 22 has, for example, a horizontal plate shape, and is fixedly supported by a support member (not shown) at a position slightly lower than the liquid level of the refrigerant 12.

  Then, when a bubble a is generated by the evaporation of the refrigerant accompanying heat generation due to normal conduction of the superconducting coil 11 and the bubble a rises above the superconducting coil 11, the bubble a contacts or permeates the bubble extinguishing means 22. Under this holding state, the bubbles a naturally disappear due to heat exchange with the surrounding refrigerant 12, pressure, and the like.

  Therefore, according to the present embodiment, the bubbles a can be naturally extinguished while the refrigerant 12 is held in the refrigerant container 13, and the increase in pressure in the refrigerant container 13 is suppressed to reduce the thickness of the container components. In addition, a decrease in dielectric strength and dielectric breakdown can be prevented, and the refrigerant container 13 can have a compact configuration with a small number of parts, and weight reduction and the like can be efficiently achieved.

[Fourth Embodiment (FIG. 4)]
FIG. 4 is a longitudinal sectional view showing a superconducting device according to a fourth embodiment of the present invention. As shown in FIG. 4, in the present embodiment, the superconducting fault current limiter is configured to accommodate the refrigerant 12 in the refrigerant container 13 surrounded by the heat insulating container 15 and immerse the superconductor 11 in the refrigerant 12 to cool it. The bubble extinguishing means for extinguishing the bubbles a generated by the heat generation when the superconductor 11 becomes normal conducting is a downward open container 23 disposed above the superconductor 11 in the refrigerant 12 in the refrigerant container 13. Will be described.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. A space is provided between the refrigerant container 13 and the heat insulation container 15, and this space is formed as a heat insulation space 14 by vacuum or heat insulation filling. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  The downward open container 23 provided inside the refrigerant container 13 includes a horizontal plate part 23a having an area covering the upper space of the superconducting coil 11 in the refrigerant 12 in the refrigerant container 13, and a lower peripheral part of the horizontal plate part 23a. It has a vertically downward opening structure having a hanging frame-like portion 13a that protrudes integrally and is fixedly supported by a support member (not shown) at a position slightly lower than the liquid level of the refrigerant 12. The material of the downward open container 23 may be metal or non-metal, but a good heat conductor such as copper or aluminum is preferable.

  Then, when the bubble a is generated by the evaporation of the refrigerant due to the heat generation due to the normal conduction of the superconducting coil 11 and the bubble a rises above the superconducting coil 11, the bubble a is trapped in the downward open container 23, Under the state, the bubbles a are crushed by heat exchange with the surrounding refrigerant 12 and recondensed (if the heat balance is used, the temperature of the refrigerant rises). In this process, a good heat conductor is preferable as the material of the downward open container 23. Further, when the refrigerant container 13 is sealed, the pressure is slightly increased and the refrigerant temperature becomes lower than the saturation temperature determined by the pressure, so that the bubble suppression effect is likely to appear.

  Therefore, according to the present embodiment, the bubbles a can be crushed while the refrigerant 12 is held in the refrigerant container 13, and an increase in pressure in the refrigerant container 13 can be suppressed, and the wall thickness of the container component can be reduced. In addition, a decrease in dielectric strength and dielectric breakdown can be prevented, and the refrigerant container 13 can have a compact configuration with a small number of parts, and weight reduction and the like can be efficiently achieved.

[Fifth Embodiment (FIG. 5)]
FIG. 5 is a longitudinal sectional view showing a superconducting device according to a fifth embodiment of the present invention. As shown in FIG. 5, in the present embodiment, the superconducting fault current limiter is configured to accommodate the refrigerant 12 in the refrigerant container 13 surrounded by the heat insulating container 15 and immerse the superconductor 11 in the refrigerant 12 to cool it. Next, a configuration in which the porous material 24 is provided inside the refrigerant container 13 as a bubble extinguishing means that eliminates the bubbles a generated by heat generation when the superconductor 11 becomes normal conducting will be described.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. A space is provided between the refrigerant container 13 and the heat insulation container 15, and this space is formed as a heat insulation space 14 by vacuum or heat insulation filling. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  The porous material 24 provided inside the refrigerant container 13 is provided so as to cover the space above the superconducting coil 11 in the refrigerant 12 in the refrigerant container 13. The porous material 24 has, for example, a horizontal plate shape, and is fixedly supported by a support member (not shown) at a position slightly lower than the liquid level of the refrigerant 12. The porous material 24 is made of a material such as foamed polyurethane, foamed glass, foamed phenol, foamed polystyrene, or fiberglass.

  Then, when the bubble a is generated by the evaporation of the refrigerant accompanying the heat generation due to the normal conduction of the superconducting coil 11 and the bubble a rises above the superconducting coil 11, the bubble a is trapped by the porous material 24 and It is crushed by heat exchange with the refrigerant 12 and recondensed. Further, when the refrigerant container 13 is sealed, the pressure is slightly increased and the refrigerant temperature becomes lower than the saturation temperature determined by the pressure, so that the bubble suppression effect is likely to appear.

  Therefore, according to the present embodiment, the bubbles a can be extinguished while the refrigerant 12 is held in the refrigerant container 13, and the increase in pressure in the refrigerant container 13 is suppressed, and the thickness of the container components is reduced. In addition, a decrease in dielectric strength and dielectric breakdown can be prevented, and the refrigerant container 13 can have a compact configuration with a small number of parts, and weight reduction and the like can be efficiently achieved.

[Sixth Embodiment (FIG. 6)]
FIG. 6 is a longitudinal sectional view showing a superconducting device according to a sixth embodiment of the present invention. As shown in FIG. 6, in the present embodiment, the superconducting fault current limiter is configured to accommodate the refrigerant 12 in the refrigerant container 13 surrounded by the heat insulating container 15 and immerse the superconductor 11 in the refrigerant 12 to cool it. A configuration in which a baffle plate 25 that prevents the generated bubbles from rising is provided inside the refrigerant container 13 as a bubble extinguishing means that eliminates the bubbles a generated by heat generation when the superconductor 11 becomes normal conducting will be described.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. A space is provided between the refrigerant container 13 and the heat insulation container 15, and this space is formed as a heat insulation space 14 by vacuum or heat insulation filling. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  The baffle plate 25 provided inside the refrigerant container 13 is configured such that a plurality of pieces are gathered in the vertical and horizontal directions and arranged close to each other, and the space above the superconducting coil 11 in the refrigerant 12 in the refrigerant container 13. It is provided in the arrangement which covers. The material of the baffle plate 25 may be metal or non-metal, but a good heat conductor such as copper or aluminum is preferable.

  Bubbles generated on the surface of the superconducting coil 11 are trapped in the baffle plate 25, and the bubbles are crushed and recondensed by heat exchange with the surrounding refrigerant. In this process, a good heat conductor is preferable as the material of the container 23. Further, when the refrigerant container 13 is hermetically sealed, the pressure is slightly increased, and the refrigerant temperature is lower than the saturation temperature determined by the pressure, so that the bubble suppression effect is likely to appear.

  According to the present embodiment, the bubbles a can be extinguished while the refrigerant 12 is held in the refrigerant container 13, the pressure increase in the refrigerant container 13 is suppressed, the thickness of the container components is reduced, and insulation is achieved. A decrease in proof stress and dielectric breakdown can be prevented, and the refrigerant container 13 can be made compact, and weight can be reduced efficiently.

[Seventh Embodiment (FIG. 7)]
FIG. 7 is a longitudinal sectional view showing a superconducting device according to a seventh embodiment of the present invention. As shown in FIG. 7, in the present embodiment, the superconducting fault current limiter is configured such that the refrigerant 12 is accommodated in the refrigerant container 13 surrounded by the heat insulating container 15, and the superconductor 11 is immersed in the refrigerant 12 to be cooled. The bubble extinguishing means for extinguishing the bubbles a generated by the heat generation when the superconductor 11 becomes normal conducting is a gas buffer layer 26 provided between the refrigerant container 13 and the heat insulating container wall 15. A configuration for guiding the bubbles a generated in the layer 26 to disappear will be described.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  A space is provided between the refrigerant container 13 and the heat insulation container 15, and a buffer gas layer 26 is formed in the space by containing a buffer gas for gas absorption. Further, at a position higher than the liquid level of the refrigerant 12 in the refrigerant container 13, a connecting pipe 27 having both end openings penetrating the wall of the refrigerant container 13 is provided, and the inner and outer peripheral spaces of the refrigerant container 13 communicate with each other. It has become. That is, the buffer gas layer 26 communicates with the space in the refrigerant container 13.

  According to such a configuration, the gas buffer layer 26 is disposed between the refrigerant container 13 and the inner wall of the heat insulating container 15 as the bubble extinguishing means, and the gas buffer layer 26 and the refrigerant container 13 are connected by the connecting pipe 27. Therefore, the bubbles generated on the surface of the superconducting coil 11 are released upward as a gas from the surface of the refrigerant 12, and then are guided to the gas buffer layer 26 via the connecting pipe 27 and disappear. The gas buffer layer 26 is preferably as close to the refrigerant container 13 as possible to reduce the temperature difference between the two tanks.

  According to this embodiment, the same operation as in the first embodiment is performed in the heat insulating container 15. However, in this embodiment, by preparing a buffer space in a low temperature environment in the heat insulating container 15, it is not necessary to raise the temperature of the evaporative gas to the room temperature region, and the effect of suppressing the pressure rise and suppressing the bubble generation is great.

  Also according to this embodiment, the bubbles a can be extinguished while the refrigerant 12 is held in the refrigerant container 13, the increase in pressure in the refrigerant container 13 is suppressed, the thickness of the container components is reduced, and the dielectric strength Reduction, dielectric breakdown, and the like can be prevented, the refrigerant container 13 can be made compact, and weight reduction and the like can be efficiently achieved.

[Eighth Embodiment (FIG. 8)]
FIG. 8 is a longitudinal sectional view showing a superconducting device according to an eighth embodiment of the present invention. As shown in FIG. 8, in the present embodiment, a superconducting fault current limiter including a refrigerator 21 in the refrigerant container 13 will be described as a bubble extinguishing means.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. A space is provided between the refrigerant container 13 and the heat insulation container 15, and this space is formed as a heat insulation space 14 by vacuum or heat insulation filling. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  An injection pipe 17 for injecting the refrigerant 12 is inserted into the lid body 15 a of the refrigerant container 13. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  In such a configuration, in the present embodiment, the refrigerator 21 is provided in the refrigerant container 13. The refrigerator 21 is a cryogenic refrigerator, and includes, for example, a refrigerator head 21a mounted on the upper surface of the lid 15a, and a cooling stage 21b of the refrigerant head provided in a suspended state below the lid 15a. I have. And the cooling stage 21b is immersed in the refrigerant | coolant 12, and becomes a structure which can recool a refrigerant | coolant. For example, the refrigerator 21 is installed at a position obliquely upward from the superconducting coil 11 in the refrigerant container 13 and promotes convection of the refrigerant 12 in the refrigerant container 13 as indicated by an arrow b in FIG. It has become. However, the cooling stage 21b may be elongated in the left direction in FIG. 8 or may be configured to cover the upper portion of the superconducting coil 11 as an inclined arrangement.

  According to this embodiment, by recondensing the refrigerant 12 by driving the refrigerator 21, the refrigerant temperature becomes lower than the saturation temperature determined by the pressure, and the bubble suppression effect appears. Thereby, a bubble extinction function can be improved and the maintenance of the resupply work of the refrigerant | coolant 12 becomes unnecessary. And it is possible to effectively prevent or suppress the decrease of the refrigerant, the effect of suppressing the pressure increase in the refrigerant container 13 to reduce the thickness of the container component, the effect of preventing the decrease of the dielectric strength and the dielectric breakdown, In addition, effects such as a compact configuration and weight reduction can be achieved.

[Ninth Embodiment (FIG. 9)]
FIG. 9 is a longitudinal sectional view showing a superconducting device according to a ninth embodiment of the present invention. As shown in FIG. 9, in this embodiment, as the bubble extinguishing means, the cross-sectional area of the boundary surface 28 part between the refrigerant 12 and the gas in the upper part in the refrigerant container 13 is made smaller than the lower cross-sectional area of the refrigerant container 13, A superconducting fault current limiter including the refrigerator 21 in the refrigerant container 13 will be described.

  The superconducting coil 11 is cooled by being immersed in a refrigerant 12 such as liquid nitrogen housed in a refrigerant container 13. The refrigerant container 13 has, for example, a cylindrical shape whose upper surface is open, and the outer periphery and the lower part of the refrigerant container 13 are covered with a heat insulating container 15. A space is provided between the refrigerant container 13 and the heat insulation container 15, and this space is formed as a heat insulation space 14 by vacuum or heat insulation filling. The upper end opening of the refrigerant container 13 and the heat insulating container 15 and the upper end opening of the heat insulating space 14 are sealed by a lid 15a made of heat insulating material, and are installed, for example, in a room temperature room.

  In this configuration, the upper end side of the refrigerant container 13 rises by bending a predetermined length toward the container center side, thereby forming an upper end small-diameter cylindrical portion 13a. The upper end small-diameter cylindrical portion 13a has a boundary surface 28 portion between the refrigerant 12 and the gas, so that the cross-sectional area of the boundary surface 28 portion between the refrigerant 12 and the gas is the lower cross-sectional area of the refrigerant container 13. The narrow portion 29 is formed so as to be smaller than that.

  Further, a pipe insertion cylinder part 13b and a refrigerator insertion cylinder part 13c are formed on the outer peripheral side of the upper end small diameter cylindrical part 13a of the refrigerant container 13. And the piping 17 for injection | pouring for inject | pouring the refrigerant | coolant 12 to the cylinder part 13b for piping insertion and the cover body 15a is penetrated. A valve 17a as a throttling device is attached to the refrigerant injection pipe 17. Further, in order to connect the superconducting coil 11 to a power source or a power system placed on the room temperature side, a current lead 16 penetrates the lid 15 and is inserted into the refrigerant container 13, and the tip of the current lead 16 is at the superconducting coil 11. It is connected to the.

  On the other hand, a refrigerator 21 is provided in the refrigerant container 13. The refrigerator 21 is a cryogenic refrigerator, and includes, for example, a refrigerator head 21a mounted on the upper surface of the lid 15a, and a cooling stage 21b of the refrigerant head provided in a suspended state below the lid 15a. I have. The refrigerator 21 is inserted into the refrigerator insertion cylinder 13c.

And the cooling stage 21b is immersed in the refrigerant | coolant 12, and becomes a structure which can recool a refrigerant | coolant. For example, the refrigerator 21 is installed at a position obliquely upward from the superconducting coil 11 in the refrigerant container 13 and promotes convection of the refrigerant 12 in the refrigerant container 13 as indicated by an arrow b in FIG. It has become. However, the cooling stage 21b may be elongated in the left direction in FIG. 8 or may be configured to cover the upper portion of the superconducting coil 11 as an inclined arrangement.

  According to this embodiment, the refrigerant container 13 has a configuration in which the cross-sectional area of the boundary surface 28 between the refrigerant 12 and the gas is smaller than the cross-sectional area of the superconducting coil located at the lower part of the refrigerant container 13. Since the narrow portion 29 is formed in the container 13, heat intrusion can be suppressed. Normally, gas condensing is likely to occur at the boundary surface 28 between the refrigerant 12 and the gas, which may lead to heat intrusion by convection from room temperature. In the present embodiment, such possibility is reduced or eliminated. can do.

  Further, according to the present embodiment, by recondensing the refrigerant 12 by driving the refrigerator 21, the refrigerant temperature becomes lower than the saturation temperature determined by the pressure, and the bubble suppression effect appears. Thereby, a bubble extinction function can be improved and the maintenance of the resupply work of the refrigerant | coolant 12 becomes unnecessary.

  Therefore, the heat penetration can be suppressed by reducing the cross-sectional area of the boundary surface 28 by forming the narrow portion 29, and the decrease in the refrigerant can be more effectively prevented or suppressed by applying the refrigerator 21. The effect of reducing the wall thickness of the container component by suppressing the pressure increase in the refrigerant container 13, the effect of reducing the dielectric strength and preventing the dielectric breakdown, and the effect of reducing the size of the structure and reducing the weight are achieved. The

[Tenth Embodiment (FIG. 10)]
FIG. 10 is a longitudinal sectional view showing a superconducting device according to a tenth embodiment of the present invention. In the present embodiment, as in the ninth embodiment, as the bubble extinguishing means, the cross-sectional area of the boundary surface 28 part between the refrigerant 12 and the gas in the upper part in the refrigerant container 13 is made smaller than the lower cross-sectional area of the refrigerant container 13, In addition, the present invention relates to a superconducting fault current limiter provided with a refrigerator 21 in the refrigerant container 13. However, as a configuration for reducing the cross-sectional area of the boundary surface 28, the refrigerant 12 in the vicinity of the boundary surface 28 between the refrigerant 12 and the gas is used. The porous material 30 is disposed, thereby constituting means for reducing the exposed portion of the boundary surface 28.

  According to such a configuration, the cross-sectional area of the boundary surface 28 can be reduced without the need to form a step or the like in the upper part of the refrigerant container 13, and the function similar to the ninth embodiment, that is, the function of suppressing heat intrusion. And the function of eliminating the bubbles a by the porous material 30 itself described in the fifth embodiment can be exhibited. And in the case of this embodiment, the bubble extinction function by the refrigerator 21 can also be obtained. Therefore, excellent effects such as suppression of the pressure increase in the refrigerant container 13, the effect of reducing the thickness of the container components, the reduction in dielectric strength, and the effect of preventing dielectric breakdown are exhibited.

[First to Sixteenth Embodiments (FIGS. 11 to 16)]
11 to 16 show the 11th to 16th embodiments, respectively. These embodiments are configured by combining two or more of the configurations of the first to tenth embodiments described above.

  FIG. 11 shows an eleventh embodiment of the present invention, which is a combination of the third embodiment and the eighth embodiment. That is, in addition to the configuration in which the bubble suppression means 22 is disposed inside the heat insulating container 15, the refrigerator 21 is provided as a cooling means for the refrigerant 12 in the refrigerant container 13. Although only the bubble suppression means 22 of 3rd Embodiment has the above-mentioned effect, the refrigerant temperature is lower than the saturation temperature determined by the pressure by the refrigerator 21, and the bubble suppression effect is obtained by combining the bubble suppression effect. To increase.

  In the configuration of FIG. 3, if the heat balance is used, there is a possibility that the temperature of the refrigerant rises due to normal conduction of the superconducting coil 11. However, by providing the refrigerator 21, the superconducting coil 11 becomes normal conduction. It is possible to return the refrigerant to the initial state with respect to the removal of the generated heat.

  FIG. 12 shows a twelfth embodiment of the present invention, which is a combination of the fourth embodiment and the eighth embodiment described above. That is, it is a superconducting device in which the refrigerant 12 is housed in the refrigerant container 13 surrounded by the heat insulating container 15 and the superconductor 11 is immersed in the refrigerant 12 for cooling, and the heat generated when the superconductor 11 becomes normal conducting. As the bubble extinguishing means for eliminating the bubbles a generated by the above, a refrigerator 21 and a downward open container 23 are provided inside the refrigerant container 13. The downward open container 23 is disposed above the superconductor 11 in the refrigerant 12 in the refrigerant container 13.

  FIG. 13 shows a thirteenth embodiment of the present invention, which is a combination of the fifth and eighth embodiments described above. That is, it is a superconducting device in which the refrigerant 12 is accommodated in the refrigerant container 13 surrounded by the heat insulating container 15 and the superconductor 11 is immersed in the refrigerant 12 and cooled, and the refrigerant in the refrigerant container 13 is used as a bubble extinguishing means. 12 includes a porous material 24 provided above the superconductor 11 and a refrigerator 21.

  FIG. 14 shows a fourteenth embodiment of the present invention, which is a combination of the sixth embodiment and the eighth embodiment described above. That is, it is a superconducting device in which the refrigerant 12 is accommodated in the refrigerant container 13 surrounded by the heat insulating container 15 and the superconductor 11 is immersed in the refrigerant 12 and cooled, and the refrigerant in the refrigerant container 13 is used as a bubble extinguishing means. 12 includes a porous material 24 provided above the superconductor 11 and a refrigerator 21.

  FIG. 15 shows a fifteenth embodiment of the present invention, which is a combination of the seventh embodiment and the eighth embodiment described above. That is, it is a superconducting device in which the refrigerant 12 is accommodated in the refrigerant container 13 surrounded by the heat insulating container 15 and the superconductor 11 is immersed in the refrigerant 12 for cooling. A configuration in which the gas buffer layer 26 is disposed between the inner wall of the container 15 and the refrigerator 21 are provided.

  FIG. 16 shows a sixteenth embodiment of the present invention, which is a combination of the seventh embodiment and the eighth embodiment described above. That is, as the bubble suppression means 22, the gas buffer layer 26 is disposed between the inner wall of the refrigerant container 13 and the heat insulating container 15, and the cross-sectional area of the boundary surface 28 between the refrigerant 12 and the gas is located at the position of the superconducting coil 11 positioned below. The container structure is smaller than the container cross-sectional area.

  In addition, in this invention, it is also possible to combine 3 or more types of embodiment mentioned above. And based on the combined component, a highly functional synergistic effect can be respectively obtained.

[Seventeenth Embodiment (FIG. 17)]
FIG. 17 is a longitudinal sectional view showing a seventeenth embodiment of the present invention. In the present embodiment, a refrigerant is contained in a refrigerant container surrounded by a heat-insulating container, and is a superconducting device that cools by immersing the superconductor in the refrigerant, and bubbles generated by heat generation when the superconductor becomes normal conducting Bubble extinguishing means for extinguishing is provided inside the refrigerant container. A superconductor for three phases serving as a current limiting element is housed in one refrigerant container, and three pairs of current leads connected to the superconducting coil are arranged asymmetrically with respect to the central axis of the upper flange of the cryostat. In addition, the superconducting current limiting device is configured by arranging the refrigerator head on the side opposite to the current lead group. In addition, a refrigerator is provided in the refrigerant container as the bubble extinguishing means.

  As shown in FIG. 17, in this embodiment, when the superconducting device is a superconducting current limiting device, superconducting current limiting coils 31a, 31b, 31c for three phases serving as current limiting elements are provided in one heat insulating container 15. It is stored. Three pairs of current leads 16a, 16b, 16c connected to the superconducting coil are not symmetrical with respect to the central axis of the upper flange of the cryostat, but are arranged on one side, and the refrigerator head 21a of the refrigerator as the cooling means 21 is connected to the current lead group 16a, It is arranged on the opposite side to 16b and 16c.

  Further, bubble generation suppression means 22 is provided in the superconducting device. In the present embodiment, the configuration of the third embodiment shown in FIG. 3 is a basic configuration, but the bubble generation suppressing means is the second embodiment, the eighth embodiment and the first embodiment shown in FIGS. Any configuration of the eleventh embodiment is possible.

  The effect of bubble suppression is as described in the above embodiments. In addition, since the current lead group and the refrigerator head are arranged on the opposite side in the configuration of the present embodiment, an effect of facilitating access to the refrigerator head during the refrigerator maintenance is achieved. This is an effect of improving safety. In addition, it is desirable in terms of the configuration that the current lead group is on the side opposite to the refrigerator head even in consideration of peeling the current lead group from the system during maintenance.

[Test Examples (FIGS. 18 and 19)]
The effect of the present invention has been verified by a simple model test. This outline will be described below.

  A schematic configuration of the test apparatus is shown in FIG. FIG. 18 shows only the minimum components of the test and includes a pressure gauge, a pressure release valve, LN2 injection, a current lead, a nitrogen container, liquid nitrogen, and the like.

  The liquid nitrogen container is thermally insulated by making the outside vacuum. A model coil in which a high-temperature superconducting wire (YBCO tape wire) was wound by 1 m in liquid nitrogen was immersed and cooled.

  During the test, an overcurrent exceeding the critical current of the superconducting wire was passed from the external power source to the model coil, and energy was applied. This is an overcurrent application that simulates the current limiting operation of the current limiter.

  As the state of the refrigerant, saturated liquid nitrogen (77 K, 1 atm, corresponding to the conventional example of the present invention), and liquid nitrogen cooled by using the cold generation means (65 K, 1 atm, FIG. 8 of the present invention). 2 cases).

  The test results are shown in FIG. In FIG. 19, the horizontal axis represents applied energy, and the vertical axis represents pressure increase. As shown in FIG. 19, it can be seen that in the case corresponding to the present invention (square black mark), the pressure rise is clearly suppressed as compared with the case corresponding to the conventional example (black circle mark). That is, the effect of suppressing bubble generation could be verified by model tests.

1 is a longitudinal sectional view showing a first embodiment of a superconducting device according to the present invention. The longitudinal cross-sectional view which shows 2nd Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 3rd Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 4th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 5th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 6th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 7th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 8th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 9th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 10th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 11th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 12th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 13th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 14th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 15th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 16th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 17th Embodiment of the superconducting apparatus which concerns on this invention. The longitudinal section showing the testing machine of the superconducting device concerning the present invention. The graph which shows the test result of the superconducting apparatus which concerns on this invention. The longitudinal cross-sectional view which shows the superconducting apparatus which shows the former.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Superconducting coil (superconducting element), 12 ... Refrigerant, 13 ... Refrigerant container, 14 ... Vacuum, 15 ... Thermal insulation container, 16 ... Current lead, 16a ... Current lead U phase, 16b ... Current lead V phase, 16c ... Current lead W phase, 17 ... injection port, 18 ... piping, 18a ... throttle part, 20 ... buffer container, 21 ... cooling means (refrigerator), 21a ... refrigerator head, 21b ... cooling stage for refrigerator head, 22 ... bubbles Extinction means, 23: Open container facing downward, 24: Porous material, 25: Baffle plate, 26: Gas buffer layer, 27: Connection pipe, 28: Interface between refrigerant and gas, 29: Narrow part, 30: Porous material 31 current limiting coil, 31a current limiting coil U phase, 31b current limiting coil V phase, 31c current limiting coil W phase, 32 discharge port.

Claims (5)

In a superconducting device that contains a refrigerant in a refrigerant container surrounded by a heat insulating container and cools the superconductor by immersing it in the refrigerant, the bubble disappears to eliminate bubbles generated by heat generation when the superconductor becomes normal conducting Providing means ,
The bubble extinguishing means includes a porous material disposed above the superconductor in the refrigerant in the refrigerant container, a downwardly opened container disposed above the superconductor in the refrigerant in the refrigerant container, and A superconducting device comprising at least one means selected from a baffle plate disposed in the refrigerant and preventing the generated bubbles from rising. Superconducting device of claim 1, wherein the gas buffer layer is provided between the front Symbol refrigerant container and the heat insulating container wall. Superconducting device of claim 1, wherein the refrigerator is provided in the prior Symbol refrigerant vessel. Before SL refrigerant container superconducting device according to claim 1, characterized in that the structure is set smaller than the cross-sectional area of the coolant vessel lower the cross-sectional area of a boundary surface between the refrigerant and the gas in its interior upper. A superconductor for three phases serving as a current limiting element is housed in one refrigerant container, and three pairs of current leads connected to the superconducting coil are arranged on one side in an asymmetrical arrangement with respect to the central axis of the upper flange of the cryostat, and refrigerator head superconducting device according to claim 1, characterized in that disposed on the opposite side of the current lead group superconducting current limiting device is constructed.

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