JP2013247323A - Cooling container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve maintainability and cooling efficiency and prevent heat intrusion.SOLUTION: A cooling container includes: a refrigerant container 20 having an inner container 21 and an outer container 22 that are vacuum-insulated from each other, and having an opening in an upper portion thereof; a lid 30 that can close the opening of the refrigerant container 20; and a freezer 40 that is supported by the lid 30. A liquid refrigerant 60 is stored in the inner container 21 of the refrigerant container 20. Cooling sections 43 and 44 of the freezer 40 penetrating through the lid 30 are supported in a suspended manner above a liquid surface of the liquid refrigerant 60 in the inner container 21. In the inner container 21, a partition wall 50 is provided that shields the cooling sections 43 and 44 as supported in the suspended manner from a refrigerant gas convected from the surroundings and above.

Description

  The present invention relates to a cooling container that cools an object to be cooled through a liquid refrigerant in the container.

  SMES (Superconducting Magnetic Energy Storage), Superconducting Transformer, Superconducting Fault Current Limiter, NMR (Nuclear Magnetic Resonance), Superconducting Magnet, etc. In the field, metallic superconducting wires represented by niobium titanium (NbTi) are used. However, superconducting metal-based superconducting wires requires cooling to the boiling point of helium (4K), which makes the cooling efficiency (COP) of the refrigerator extremely low and consumes a lot of power. And helium is expensive in itself.

Usually, a superconducting wire is coiled and stored in a vacuum insulated container called a cryostat for cooling. The thermal insulation performance of this cryostat greatly affects the operating cost of the equipment. In general, the refrigerating capacity of a helium refrigerator is about 1 W, and if the intrusion heat into the cryostat is larger than this, a plurality of refrigerators are mounted, and the amount of electric power used is greatly increased. If it is not added, helium will gradually evaporate and escape, and it will be very expensive to replenish helium.
Therefore, in order to reduce energy costs and operational costs, research for switching to high-temperature superconducting wires (oxides) currently under development is being advanced. This is because if this high-temperature superconducting wire is used, superconductivity is realized at a higher temperature, and it is possible to use cheaper nitrogen instead of helium as the refrigerant.
However, it has been desired to develop a cryostat with as little intrusion heat as possible regardless of which refrigerant is used.

  In the conventional cooling container shown in Patent Document 1, an inner tank that stores liquid nitrogen as a refrigerant and a superconducting coil, an outer tank that stores the entire inner tank, and a refrigeration head in which a freezing head extends to the inside of the inner tank. And a vacuum insulation structure is formed by evacuating the inner and outer tanks to prevent heat intrusion.

  Moreover, in the conventional cooling container shown in Patent Document 2, the space between the inner wall and the outer wall is evacuated, liquid nitrogen is stored in a refrigerant tank having a double wall structure with an open upper part, and the upper part of the refrigerant tank is closed. The lid plate is equipped with a refrigerator, and the heat transfer member is suspended from the cooling head to near the liquid level for cooling.

JP 2006-165418 A JP 2009-283679 A

However, since the cooling container described in Patent Document 1 is disposed inside the inner tank in which the cooling head and the superconducting coil of the refrigerator are difficult to open and close, the attachment of the refrigerator requiring regular maintenance, Removal and maintenance of the superconducting coil were extremely difficult.
Furthermore, since this cooling container has a structure in which the cooling head is immersed and cooled in liquid nitrogen, there is a problem in that heat penetration occurs through the cooling head when the refrigerator is stopped, and the temperature inside the tank rises. there were.

On the other hand, in the cooling container described in Patent Document 2, the refrigerant tank is provided with a cover plate, and the inside of the refrigerant tank can be accessed by opening the cover plate, thereby improving maintenance performance.
In addition, the cooling head of the refrigerator and the heat transfer member suspended from the cooling head are illustrated as a configuration that does not contact the liquid surface. In this example, the effect of suppressing heat intrusion from the refrigerator is illustrated. There is.
However, in the case of the structure of the cited document 2, the refrigerant gas in contact with the cooling head and the heat transfer member is liquefied, so that the surrounding refrigerant gas is collected, thereby generating convection inside the refrigerant tank. . As a result, warm refrigerant gas in the vicinity of the cover plate that is not provided with a vacuum insulation structure is also concentrated by the convection to the cooling head and the heat transfer member, so that the refrigerator cools the refrigerant gas warmed to near room temperature to near the boiling point. There is a problem that it is necessary to perform work and work of vaporization latent heat for liquefaction, and as a result, the refrigerator has a large refrigeration capacity.
Further, when convection occurs, the cover plate is cooled, and moisture in the outside air is condensed on the upper surface of the cover plate. Further, when a current lead or the like for energizing the superconducting wire cooled in the cooling container is provided on the cover plate, there is a problem that insulation may be lowered due to condensed moisture.

  An object of the present invention is to provide a cooling container that is easy to maintain, has little heat penetration, and has high cooling efficiency.

  The present invention includes a refrigerant container having an inner container and an outer container, vacuum-insulated between them and having an opening in the upper part, a lid capable of closing the opening of the refrigerant container, and the lid And a cooling unit of the refrigerator that penetrates the lid body, and the cooling unit of the refrigerator that passes through the lid is located above the liquid level of the liquid refrigerant in the inner container. In the inner container, the cooling unit supported by the hanger is provided with a partition wall that shields the cooling unit hung from the convection refrigerant gas from the periphery and above.

The partition wall may have a side wall that covers the periphery of the cooling unit.
Furthermore, you may comprise the said partition part which has a top-plate part which covers the upper direction of the said cooling part.

  Moreover, the upper end part of the said side wall part is in contact with the lower surface of the said cover body, and it is good also as a structure which surrounds the circumference | surroundings and upper direction of the said cooling part by cooperation with the said side wall part and the said cover body.

Moreover, it is good also as a structure which fills the circumference | surroundings of the cooling part of the said refrigerator to the range which reaches the inner wall of the said inner container with a heat insulating material.
Furthermore, the said heat insulating material is good also as a structure fixed to the said cover body or the said partition part.

  Moreover, it is good also as a shape which diameter-expands the side wall part of the said partition part as it goes below.

  The liquid refrigerant may be liquid nitrogen.

  Further, a current lead for energizing the superconducting device may be provided through the lid.

The present invention includes a lid that can be opened and closed in the refrigerant container, so that access to the inside is facilitated, and maintenance work relating to the cooling unit of the refrigerator and the object to be cooled can be easily performed. .
In addition, since the cooling unit of the refrigerator is supported below the liquid level of the liquid refrigerant in the inner container, it is possible to prevent the cooling unit and the liquid refrigerant from contacting each other and prevent heat from entering from the refrigerator.
Here, the “cooling section” refers to a low temperature portion that produces a cooling effect on the outside in the refrigerator. For example, in the case of a regenerative refrigerator using a cylinder, the end of the cylinder on the low temperature side is shown.

  Further, since the present invention includes the partition wall portion, the convection refrigerant gas from the periphery and the upper side can be shut off from the cooling portion supported by the drooping, thereby preventing the convection of the refrigerant gas in the inner container. In addition to being suppressed, the cooling capacity for the work for cooling the refrigerant gas heated near the lid to near the boiling point becomes unnecessary, and efficient cooling can be performed. This also makes it possible to replace the refrigerator with a smaller one having a smaller capacity.

  Also, the refrigerator penetrates the lid, the cooling part is supported at the end of the refrigerator, and the partition part is equipped to cover the periphery of the cooling part, so these can be removed integrally Yes, workability during maintenance can be improved.

Moreover, when it is set as the structure which fills the circumference | surroundings of the cooling part of a refrigerator to the range which reaches the inner wall of an internal container with a heat insulating material, the heat penetration | invasion from a cover body can be prevented effectively.
Further, when the heat insulating material is fixed to the lid or the partition wall, they can be removed integrally, and workability during maintenance can be improved.

  When the diameter of the side wall of the partition wall is increased toward the lower side, the refrigerant gas vaporized from the liquid refrigerant surface can be effectively guided to the cooling unit, and before reaching the vicinity of the lid and being warmed It can be liquefied and can be cooled efficiently.

  When the liquid refrigerant is liquid nitrogen, the cooling temperature can be set higher than when helium is used as the refrigerant, and the allowable range of the amount of heat for heat intrusion is increased. It is also possible to change to. Also, unlike helium, which is easy to consume and expensive, liquid nitrogen is low in cost and low in consumption, so that it is possible to reduce running costs.

When the lid is equipped with the current lead of the superconducting device, it is possible to easily perform maintenance such as wiring work, periodic inspection, and repair for the superconducting device.
In addition, even when the lid is equipped with a current lead penetrating, the partition wall prevents convection of the refrigerant gas, thereby reducing the occurrence of condensation due to cooling on the upper surface of the lid and preventing the insulation from deteriorating. Can be achieved.

It is sectional drawing along the perpendicular plane of the cryostat which concerns on embodiment of invention. It is sectional drawing along the vertical plane of the cryostat as a comparative example. It is sectional drawing which abbreviate | omitted the one part structure which shows the other example of a partition part. It is sectional drawing which abbreviate | omitted the one part structure which shows the other example of a partition part. It is sectional drawing which abbreviate | omitted the one part structure which shows the other example of a partition part. It is sectional drawing which abbreviate | omitted the one part structure which shows the other example of a partition part. It is sectional drawing which abbreviate | omitted the one part structure which shows the other example of a partition part. It is sectional drawing which abbreviate | omitted the one part structure which shows the other example of a partition part. It is sectional drawing which abbreviate | omitted the one part structure which shows the other example of a partition part. FIG. 3 is a diagram illustrating a refrigerant gas temperature in a refrigerant container, a liquid refrigerant liquid surface temperature, a temperature change in the surface temperature of a heat exchanger, and a refrigerant gas pressure change in the cryostat of FIG. 2. FIG. 2 is a diagram illustrating a refrigerant gas temperature in a refrigerant container, a liquid refrigerant liquid surface temperature, a temperature change in the surface temperature of a heat exchanger, and a refrigerant gas pressure change in the cryostat of FIG. 1. FIG. 10 is a diagram illustrating a refrigerant gas temperature in a refrigerant container, a liquid refrigerant liquid surface temperature, a temperature change in the surface temperature of a heat exchanger, and a refrigerant gas pressure change in the cryostat of FIG. 9.

[Outline of Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In this embodiment, a cryostat 10 as a cooling container that accommodates a superconducting coil 90 as a superconducting device and performs cooling will be described. FIG. 1 is a cross-sectional view of the cryostat 10 taken along a vertical plane.
The cryostat 10 includes a refrigerant container 20 that houses liquid nitrogen that is a liquid refrigerant and a superconducting coil 90 that is an object to be cooled, a lid 30 that can close an upper opening of the refrigerant container 20 that is open at the top, and a refrigerant container. The refrigerator 40 that cools the inside of the refrigerator 20 and the partition wall 50 that blocks the convection refrigerant gas from around and above the cooling unit of the refrigerator 40 are provided.

[Refrigerant container]
The refrigerant container 20 is composed of an inner container 21 and an outer container 22, and is a bottomed container having a double wall structure in which the two are vacuum-insulated.
The inner container 21 has a cylindrical shape along the vertical direction, and the lower end portion is closed to form a bottom portion, and the upper end portion is opened.
The outer container 22 is also cylindrical in the vertical direction, with the lower end closed to form the bottom and the upper end open. The outer container 22 is formed to be slightly larger than the inner container 21, and stores the inner container 21 inside. Furthermore, the upper ends of the inner container 21 and the outer container 22 are joined together so that the outer peripheral surface and bottom bottom surface of the inner container 21 and the inner peripheral surface and bottom upper surface of the outer container 22 form a gap space. It has become. Further, the gap space between the inner container 21 and the outer container 22 is joined while maintaining a sealed state in a state where evacuation is performed.
Further, in the gap space between the inner container 21 and the outer container 22, there is a super insulation material 23 formed by laminating a polyester film on which aluminum is vapor-deposited over the entire area of the cylindrical portion and the bottom portion. The radiant heat is cut off.

[Lid]
The joint between the inner container 21 and the outer container 22 is horizontally smoothed, and a disk-shaped lid 30 is mounted on the ring-shaped smooth surface.
The lid 30 is attached in a state where it can be detached from the refrigerant container 20 so that the inside of the refrigerant container 20 can be accessed. For example, the lid 30 is fixed to the refrigerant container 20 by a well-known method such as a fitting structure based on an uneven shape between the lid 30 and the refrigerant container 20 or bolting.
In addition, since this lid 30 mounts the refrigerator 40 and supports the superconducting coil 90 in a suspended manner, the lid 30 is formed of a material having as much heat insulation as possible while having a strength capable of supporting these. .

  In addition, a superconducting coil 90 as a superconducting device is accommodated in the inner container 21 described above. The lid 30 is fixedly equipped with two current leads 91, 91 connected to the superconducting coil 90 in a vertically penetrating manner. One end of each of the current leads 91, 91 is connected to a power supply device of a superconducting coil 90 (not shown), and the other end is connected to a cable drawn from the superconducting coil 90 in the refrigerant container 20. Each of the current leads 91 and 91 has an insulating film formed of epoxy or the like on the surface thereof, and is closely attached to the lid body 30 through the coating film, so that the lid body 30 is removed from the refrigerant container 20. Thus, the superconducting coil 90 can be taken out from the refrigerant container 20 through the current leads 91, 91, and the superconducting coil 90 can be easily maintained.

[refrigerator]
The refrigerator 40 is a cold storage type so-called GM refrigerator, and has a cylinder source 41 that reciprocates a displacer container that holds a cold storage material up and down, and a motor that gives a vertical movement operation to the displacer container as a driving source. The drive part 42 in which the crank mechanism was stored, and the heat exchanger 44 as a heat exchange member provided in the low temperature transmission part 43 in which the cylinder part 41 becomes the lowest temperature are provided.
The refrigerator 40 is connected to a compressor or the like (not shown), and refrigerant gas is sucked into and exhausted from the inside thereof.

In the refrigerator 40, the drive unit 42 is attached to the center of the upper surface of the lid body 30, and the cylinder portion 41 passes through the lid body 30 and hangs down inside the refrigerant container 20.
In the cylinder portion 41, adiabatic compression and heat absorption are performed in the process in which the refrigerant gas moves downward in the cylinder portion 41, and its lower end portion is in the lowest temperature state.
And the low-temperature transmission part 43 is formed in the lower end part of this cylinder part 41 used as the lowest temperature. The low temperature transmission part 43 is formed in a circular flat plate shape having a larger bottom area than the lower part of the cylinder part 41, and the thermal conductivity with the surroundings is enhanced.
The heat exchanger 44 is formed of a material having a high thermal conductivity equivalent to or higher than that of the cylinder portion 41. Moreover, the upper part of the heat exchanger 44 adheres to the bottom face of the low-temperature transmission part 43, and the lower part is formed with a plurality of fins extending downward. With this structure, the heat exchanger 44 has a structure in which the contact area with the surrounding refrigerant gas is expanded, the thermal conductivity with the refrigerant gas is further increased, and a high cooling effect on the refrigerant gas is obtained. .
The low temperature transfer unit 43 and the heat exchanger 44 function as a cooling unit for the refrigerator 40.

[Partition wall]
The partition wall portion 50 is fixedly supported by the cylinder portion 41 of the refrigerator 40 in the refrigerant container 20, surrounds the upper side of the low temperature transfer portion 43 and the heat exchanger 44 that are cooling portions and the periphery thereof, and excludes the lower portion. The refrigerant gas from all directions is blocked.
The partition wall portion 50 includes a top plate portion 51 fixed to the cylinder portion 41 in a state where the cylinder portion 41 penetrates and a cylindrical side wall portion 52, and the top plate portion closes the upper end portion of the side wall portion 52. 51 is integrally joined. In addition, the partition wall 50 has a lower thermal conductivity than the low temperature transfer unit 43 and the heat exchanger 44, for example, stainless steel, or a so-called foamed resin heat insulating material such as foamed polyurethane, foamed polyethylene, FRP, low temperature, etc. It is formed from a resistant resin or the like.

The top plate portion 51 of the partition wall portion 50 is fixed to the cylinder portion 41 in a state where the outer diameter is somewhat larger than that of the low temperature transmission portion 43 and a gap is formed so as not to contact the upper surface of the low temperature transmission portion 43.
The side wall portion 52 is provided with a top plate portion 51 at an upper end portion and is open at a lower end portion. And the inner diameter is somewhat larger than the outer diameters of the low temperature transfer part 43 and the heat exchanger 44, and it is in a state of being included so as not to contact them.
Further, the side wall 52 and the heat exchanger 44 described above have a lower end that is close to the upper limit height of the liquid level 61 of the liquid refrigerant 60 in the refrigerant container 20 and does not reach the upper limit height of the liquid level 61. Is set. That is, the amount of the liquid refrigerant 60 accommodated in the refrigerant container 20 is managed so that the liquid level 61 does not exceed the prescribed upper limit height.
When a replenishing device for automatically replenishing the liquid refrigerant 60 is provided in the refrigerant container 20, a liquid level detection device is provided in the refrigerant container 20, and the liquid level 61 does not exceed the prescribed upper limit height. It is desirable to control the replenisher.

[Technical effects of the embodiment]
FIG. 2 shows a cryostat 10X as a comparative example in which the partition wall 50 is removed from the cryostat 10. When the partition wall 50 is not present as in the cryostat 10X, the liquid refrigerant 60 in the refrigerant container 20 is vaporized by heat intrusion from the lid 30 side or heat generated from the superconducting coil 90 to generate refrigerant gas. To do. When cooling by the refrigerator 40 is performed in such a state, the refrigerant gas is cooled around the low-temperature transmission unit 43 and the heat exchanger 44, liquefied, and returned to the lower liquid refrigerant 60. As a result, the refrigerant gas warmed in the vicinity of the lid 30 is also attracted to the low temperature transfer portion 43 and the heat exchanger 44, and the refrigerant gas rising from the liquid level 61 as shown by the arrow Y shown in FIG. A convection of refrigerant gas gathering on the refrigerator 40 side along the lower surface and descending along the cylinder portion 41 is formed. Thereby, since the refrigerant | coolant gas heated by the lower side of the cover body 30 is cooled to liquefaction temperature, and also the work for liquefying gas is required, a huge cooling capability is needed.

On the other hand, in the cryostat 10, the partition wall 50 surrounds the upper part and the periphery of the low-temperature transfer part 43 and the heat exchanger 44, so that the refrigerant gas entering from the lower side of the partition wall 50 is mainly cooled, and the liquid refrigerant Therefore, the convection of the refrigerant gas as in the cryostat 10X does not occur, and a small convection mainly occurs between the liquid surface and the heat exchanger 44. Therefore, a state in which the refrigerant gas heated on the back of the lid 30 is liquefied is less likely to occur, and the required cooling capacity can be reduced. Thus, the refrigerator 40 can be replaced with a smaller one having a smaller capacity. In addition, the power consumption of the refrigerator 40 can be reduced.
Further, since the partition wall portion 50 is formed of a heat insulating material, it is possible to prevent the refrigerant gas in the partition wall portion 50 from being warmed by the outer refrigerant gas and impair the cooling efficiency, thereby enabling efficient cooling. It becomes.
Moreover, since the top plate portion 51 and the side wall portion 52 are neither in contact with or in close contact with the low temperature transfer portion 43 and the heat exchanger 44, the partition wall portion 50 is efficient over the entire surfaces of the low temperature transfer portion 43 and the heat exchanger 44. It is possible to cool the refrigerant gas well.

In addition, since the cryostat 10 is equipped with the current leads 91 and 91 fixed to the lid body 30 and the lid body 30 can be detached from the refrigerant container 20, access to the superconducting coil 90 and the refrigerant container 20 is facilitated and maintenance is performed. It is possible to improve the property.
Furthermore, although the current lead 91, 91 is provided on the lid 30, since the convection of the refrigerant gas by the partition wall 50 is suppressed, the cooling to the lid 30 itself is suppressed, and condensation on the upper surface is reduced, It is possible to prevent the insulation of the current leads 91 and 91 from being lowered.
Further, since the liquid refrigerant stored in the refrigerant container 20 is liquid nitrogen, the cooling temperature can be set higher than when helium is used as the refrigerant, and the allowable range of the heat amount of heat intrusion is increased. It becomes possible to replace the machine 40 with a smaller one having a smaller capacity. Also, unlike helium, which is easy to consume and expensive, liquid nitrogen is low in cost and low in consumption, so that it is possible to reduce running costs.

[Other examples of partition wall (1)]
FIG. 3 shows a cryostat 10A having a partition wall portion 50A as another example with a part omitted. The configuration of the cryostat 10A other than the partition 50A is the same as that of the cryostat 10.
50 A of this partition part does not have the top-plate part 51, but consists only of the cylindrical side wall part opened up and down, the upper end part adheres to the lower surface of the cover body 30, and a lower end part is liquid refrigerant 60 It hangs down in a state extending to near the upper limit height of the liquid surface 61. The partition wall portion 50A is formed of the same material as the partition wall portion 50 described above. The inner diameter of the partition wall 50A is set to a value that is somewhat larger than the outer diameters of the low-temperature transfer section 43 and the heat exchanger 44 and can maintain a non-contact state with these.
That is, the partition wall portion 50A can shield the low-temperature transfer portion 43 and the heat exchanger 44 of the refrigerator 40 from the convection refrigerant gas from the periphery and above by cooperation with the lid 30. Since the refrigerant gas entering from the lower side of the partition wall 50A is mainly cooled and returned to the liquid refrigerant, the convection of the refrigerant gas hardly occurs, and a small convection between the liquid surface and the heat exchanger 44 occurs. Mainly occurs. Therefore, the required cooling capacity can be reduced, the refrigerator 40 can be downsized, and the power consumption of the refrigerator 40 can be reduced.
Moreover, it becomes possible to improve cooling efficiency by forming the said partition part 50A with a heat insulating material.
Further, since the partition wall portion 50A is not in contact with or in close contact with the low temperature transfer portion 43 and the heat exchanger 44, it is possible to efficiently cool the refrigerant gas over the entire surfaces of the low temperature transfer portion 43 and the heat exchanger 44. is there.
Further, the partition wall portion 50A is made of a cylindrical member and may be fixed to the lid body 30. Therefore, there is an advantage that manufacture and assembly are facilitated.
Further, since the partition wall portion 50A is not structured to be supported by the cylinder portion 41 of the refrigerator 40, the durability of the refrigerator 40 can be improved without giving a load to the cylinder portion 41.

[Other examples of partition walls (2)]
FIG. 4 shows a cryostat 10B having a partition wall 50B as another example with a part thereof omitted. The configuration of the cryostat 10B other than the partition 50B is the same as that of the cryostat 10.
The partition wall portion 50B fills almost the entire region above the upper limit height of the liquid surface 61 of the liquid refrigerant 60 in the refrigerant container 20, and the partition wall portion 50 is made of stainless steel or a so-called foamed resin heat insulating material such as foamed polyurethane. It is made of foamed polyethylene, FRP, low temperature resistant resin, or the like, and has an insertion hole 53 </ b> B penetrating vertically through the cylinder portion 41, the low temperature transmission portion 43 and the heat exchanger 44 of the refrigerator 40. The partition 50B has an upper end fixed to the lower surface of the lid 30 and a lower end set to a thickness close to the upper limit height of the liquid surface 61.
Further, the inner diameter of the insertion hole 53B is set to a value that is somewhat larger than the outer diameters of the low-temperature transfer section 43 and the heat exchanger 44 and can maintain a non-contact state with these.
Further, a slight gap is formed on the outer peripheral surface with respect to the inner surface of the inner container 21, thereby improving workability such as removal of the lid 30. From the viewpoint of preventing convection of the refrigerant gas, the gap should be small.
In addition, a through hole through which the two current leads 91 and 91 are passed is formed in the partition wall portion 50B.

With this structure, the partition wall 50B can shield the low-temperature transmission unit 43 and the heat exchanger 44 of the refrigerator 40 from the convection refrigerant gas from the periphery and from above, and from the lower side of the partition wall 50B to the inside. Since the incoming refrigerant gas is mainly cooled and returned to the liquid refrigerant, the convection of the refrigerant gas hardly occurs, and a small convection mainly occurs between the liquid surface and the heat exchanger 44. Therefore, the required cooling capacity can be reduced, the refrigerator 40 can be downsized, and the power consumption of the refrigerator 40 can be reduced.
Further, since the partition wall portion 50B is not in contact with or in close contact with the low temperature transfer portion 43 and the heat exchanger 44, it is possible to efficiently cool the refrigerant gas over the entire surfaces of the low temperature transfer portion 43 and the heat exchanger 44. is there.
Moreover, since the partition 50B fills the entire region above the liquid level 61 of the liquid refrigerant 60, the refrigerant gas reaching the lower surface of the lid 30 is reduced as much as possible, and the rise in the refrigerant gas temperature is effectively suppressed. To do. Further, since the partition wall 50B fills the entire region above the liquid level 61 of the liquid refrigerant 60, almost the entire refrigerant gas vaporized from the liquid level is guided into the insertion hole 53B, and most of the generated refrigerant gas. Can be cooled by the low-temperature transfer section 43 and the heat exchanger 44, and more efficient cooling can be performed. For this reason, it becomes possible to use a further smaller refrigerator 40.
Moreover, since the partition part 50B consists of a heat insulating material, it is possible to prevent the heat | fever penetration | invasion from the cover body 30 effectively. Moreover, since the partition wall 50B fills the space for generating the convection of the refrigerant gas, it is possible to effectively prevent the convection.
In addition, the space from the upper surface of the low-temperature transmission part 43 to the lower surface of the lid 30 may be filled with the heat insulating material of the partition wall part 50B. With such a structure, it is possible to reduce the amount of refrigerant gas that wraps around the low-temperature transmission unit 43 and to increase the cooling efficiency. In this case, it is desirable to provide a gap between the heat insulating material and the upper surface of the low temperature transmission part 43.

[Other examples of partition walls (3)]
FIG. 5 shows a cryostat 10 </ b> C provided with a partition wall 50 </ b> C as another example, with a part omitted. The configuration of the cryostat 10C other than the partition 50C is the same as that of the cryostat 10.
The partition wall portion 50C is provided around the lower portion of the heat exchanger 44, and fills the substantially entire region above the upper end position of the side wall portion 52C in the refrigerant container 20 and the cylindrical side wall portion 52C having an open top and bottom. The heat insulating block 54C is made of the same material as that of the partition wall 50.
The upper end portion of the side wall portion 52C is fixed to the lower surface of the heat insulating block 54C, and the lower end portion is suspended in a state of extending to near the upper limit height of the liquid surface 61 of the liquid refrigerant 60. Further, the inner diameter of the side wall portion 52C is set to a value that is somewhat larger than the outer diameters of the low temperature transfer portion 43 and the heat exchanger 44 and can maintain a non-contact state with these.
The heat insulation block 54 </ b> C has an insertion hole 53 </ b> C penetrating vertically through the cylinder portion 41, the low temperature transfer portion 43, and the heat exchanger 44 of the refrigerator 40, and communicates integrally with the inside of the side wall portion 52 </ b> C. Yes. Further, the heat insulating block 54C has an upper end fixed to the lower surface of the lid 30 and a thickness set so that the lower end is the height of the upper end of the side wall 52C.
In the example of the partition wall portion 50C, the side wall portion 52C and the heat insulating block 54C are set to substantially the same thickness, but the height ratio may be appropriately changed.
Further, the outer peripheral surface of the heat insulating block 54 </ b> C is formed with a slight gap with respect to the inner surface of the inner container 21, thereby improving workability such as removal of the lid 30. From the viewpoint of preventing convection of the refrigerant gas, the gap should be small.
The heat insulating block 54C is formed with a through hole through which the two current leads 91 and 91 are passed.

With this structure, the partition wall portion 50C can shield the low-temperature transfer portion 43 and the heat exchanger 44 of the refrigerator 40 from the convection refrigerant gas from the periphery and from above, and from the lower side of the partition wall portion 50C to the inside. Since the incoming refrigerant gas is mainly cooled and returned to the liquid refrigerant, the convection of the refrigerant gas hardly occurs, and a small convection mainly occurs between the liquid surface and the heat exchanger 44. Therefore, the required cooling capacity can be reduced, the refrigerator 40 can be downsized, and the power consumption of the refrigerator 40 can be reduced.
Further, since the partition wall portion 50C is not in contact with or in close contact with the low temperature transfer portion 43 and the heat exchanger 44, it is possible to efficiently cool the refrigerant gas over the entire surface of the low temperature transfer portion 43 and the heat exchanger 44. is there.
Further, since the heat insulating block 54C fills the entire region below the lid body 30, the refrigerant gas reaching the lower surface of the lid body 30 is reduced as much as possible, and the rise in the refrigerant gas temperature is effectively suppressed. Further, since the heat insulating block 54C is made of a heat insulating material, it is possible to effectively prevent heat from entering from the lid 30. Thereby, generation | occurrence | production of the convection of refrigerant | coolant gas can be suppressed effectively, and it becomes possible to cool refrigerant gas effectively. For this reason, the refrigerator 40 can be downsized. Further, since the partition wall portion 50C fills the convection generation space of the refrigerant gas over a wide range, it is possible to effectively prevent convection.
In addition, the space from the upper surface of the low-temperature transmission part 43 to the lower surface of the lid 30 may be filled with the heat insulating material of the partition wall part 50C. With such a structure, it is possible to reduce the amount of refrigerant gas that circulates above the low-temperature transmission unit 43 and increase the heat recovery exchange rate for the liquid level. In this case, it is desirable to provide a gap between the heat insulating material and the upper surface of the low temperature transmission part 43.

[Other examples of partition walls (4)]
FIG. 6 shows a cryostat 10D having a partition 50D as another example, with a part omitted. The configuration of the cryostat 10D other than the partition 50D is the same as that of the cryostat 10.
The partition wall portion 50D does not have the top plate portion 51, and has a cylindrical side wall portion 52D that is open at the top and bottom, and a bottom plate portion that covers the entire area from the lower end portion of the side wall portion 52D to the inner peripheral surface of the inner container 21. 55D, and the entirety of the partition wall portion 50D is formed of the same material as that of the partition wall portion 50 described above.
The upper end portion of the side wall portion 52 </ b> D is fixed to the lower surface of the lid body 30, and the lower end portion is suspended to near the upper limit height of the liquid surface 61 of the liquid refrigerant 60. Further, the inner diameter of the side wall 52D is set to a value that is somewhat larger than the outer diameters of the low temperature transfer section 43 and the heat exchanger 44 and can maintain a non-contact state with these.
Further, the bottom plate portion 55D extends outward from the lower end portion of the side wall portion 52D to the vicinity of the inner surface of the inner container 21, and excludes the portion directly below the heat exchanger 44, so that the liquid surface 61 of the liquid refrigerant 60 has a liquid surface 61. Covers the whole. In addition, although the outer periphery of bottom plate part 55D forms the clearance gap between the inner surfaces of the inner side container 21, since the said clearance gap produces the convection of refrigerant | coolant gas, it is desirable to make it narrower.
In addition, a through hole through which the two current leads 91 and 91 are passed is formed in the bottom plate portion 55D of the partition wall portion 50D.

With this structure, the partition wall portion 50D can shield the low temperature transfer portion 43 and the heat exchanger 44 of the refrigerator 40 from the convection refrigerant gas from the periphery and from above, and from the lower side of the partition wall portion 50D to the inside. Since the incoming refrigerant gas is mainly cooled and returned to the liquid refrigerant, the convection of the refrigerant gas hardly occurs, and a small convection mainly occurs between the liquid surface and the heat exchanger 44. Therefore, the required cooling capacity can be reduced, the refrigerator 40 can be downsized, and the power consumption of the refrigerator 40 can be reduced.
Further, since the partition wall portion 50D is not in contact with or in close contact with the low temperature transfer portion 43 and the heat exchanger 44, it is possible to efficiently cool the refrigerant gas over the entire surface of the low temperature transfer portion 43 and the heat exchanger 44. is there.
In addition, since the bottom plate portion 55D covers almost the entire liquid surface 61 of the liquid refrigerant 60, the partition wall portion 50D reduces the refrigerant gas reaching the lower surface of the lid 30 as much as possible, and effectively increases the refrigerant gas temperature. To suppress. Further, almost all of the refrigerant gas evaporated from the liquid surface is guided to the inside of the side wall portion 52D by the bottom plate portion 55D, and most of the generated refrigerant gas can be cooled by the low temperature transfer portion 43 and the heat exchanger 44. It becomes possible to increase the exchange rate of heat recovery for the liquid level. For this reason, it becomes possible to use a further smaller refrigerator 40.
In addition, the space from the upper surface of the low-temperature transmission part 43 to the lower surface of the lid 30 may be filled with the heat insulating material of the partition wall part 50D. With such a structure, it is possible to reduce the amount of refrigerant gas that circulates above the low-temperature transmission unit 43 and increase the heat recovery exchange rate for the liquid level. In this case, it is desirable to provide a gap between the heat insulating material and the upper surface of the low temperature transmission part 43.
Alternatively, a top plate portion 51 is provided at the upper end of the side wall portion 52D of the partition wall portion 50D in the same manner as the partition wall portion 50, and the entire partition wall portion 50D is fixed to the cylinder portion 41 of the refrigerator 40 by the top plate portion 51. It is good also as a structure to support. Also in this case, it is possible to reduce the amount of the refrigerant gas that circulates above the low temperature transmission unit 43 and increase the heat recovery exchange rate with respect to the liquid level.

[Other examples of partition walls (5)]
FIGS. 7 and 8 illustrate the cryostats 10E and 10F including the partition walls 50E and 50F as other examples, respectively, with a part omitted. The configurations of the cryostats 10E and 10F other than the partition walls 50E and 50F are the same as those of the cryostat 10.
These partition walls 50E and 50F are each composed of a side wall portion surrounding the cylinder portion 41, the low temperature transfer portion 43 and the heat exchanger 44 of the refrigerator 40, and the upper end portion of the side wall portion is the lid 30. The lower end portion of the side wall portion is fixed to the lower surface, and the diameter of the side wall portion increases toward the lower side and is close to the inner surface of the inner container 21. The lower end portions of the partition portions 50E and 50F extend downward to near the upper limit height of the liquid surface 61 of the liquid refrigerant 60.
The partition walls 50E and 50F are made of the same material as the partition wall 50 described above, and the inner diameters of the upper ends of the partition walls 50E and 50F are set somewhat larger than the outer diameter of the cylinder part 41. And it is set to a value that can maintain a non-contact state with the cylinder portion 41. Moreover, although the outer periphery of the lower end part of the partition parts 50E and 50F forms the clearance gap between the inner surfaces of the inner side container 21, since the said clearance gap produces the convection of refrigerant gas, it is desirable to make it narrower.
The partition wall 50E has a shape that is straightly inclined and expands in diameter, and the partition wall 50F has a shape that is curved and expanded in diameter so that the cross-sectional shape is concave inward.
Further, the partition walls 50E and 50F are formed with through holes through which the two current leads 91 and 91 are passed.

With this structure, the partition portions 50E and 50F can shield the low temperature transfer portion 43 and the heat exchanger 44 of the refrigerator 40 from the convective refrigerant gas from the periphery and from above, and the partition portions 50E and 50F. The refrigerant gas entering from the lower side is mainly cooled and returned to the liquid refrigerant, so that the convection of the refrigerant gas hardly occurs and a small convection mainly occurs between the liquid surface and the heat exchanger 44. . Therefore, the required cooling capacity can be reduced, the refrigerator 40 can be downsized, and the power consumption of the refrigerator 40 can be reduced.
Moreover, since the partition walls 50E and 50F are not in contact with or in close contact with the low temperature transfer section 43 and the heat exchanger 44, the cooling gas can be efficiently cooled over the entire surfaces of the low temperature transfer section 43 and the heat exchanger 44. Is possible.
Further, since the lower end portions of the partition walls 50E and 50F cover almost the entire liquid surface 61 of the liquid refrigerant 60, the refrigerant gas reaching the lower surface of the lid body 30 is reduced as much as possible to increase the refrigerant gas temperature. Effectively suppress. In addition, the lower end portion can cool almost all of the refrigerant gas evaporated from the liquid level to the low-temperature transfer section 43 and the heat exchanger 44, and can increase the exchange rate of heat recovery with respect to the liquid level. Become. For this reason, it becomes possible to use a further smaller refrigerator 40.
In addition, the partition walls 50E and 50F have a shape in which the lower end portion is enlarged in diameter, and the outer peripheral surface is formed with a slight gap with respect to the inner surface of the inner container 21, thereby The workability such as removal is improved. From the viewpoint of preventing convection of the refrigerant gas, the gap should be small.
In addition, the top plate part 51 is provided in the upper end part of the partition parts 50E and 50F similarly to the partition part 50, and the partition parts 50E and 50F are fixedly supported by the cylinder part 41 of the refrigerator 40 by the top plate part 51. It is good also as a structure. With such a structure, it is possible to reduce the amount of refrigerant gas that circulates above the low-temperature transmission unit 43 and increase the heat recovery exchange rate for the liquid level.

[Other examples of partition wall (6)]
FIG. 9 shows a cryostat 10G having a partition wall portion 50G as another example with a part thereof omitted. The configuration of the cryostat 10G other than the partition 50G is the same as that of the cryostat 10.
The partition wall portion 50G includes the partition wall portion 50 described above and a heat insulating material 53G that fills almost the entire region from the outer periphery of the partition wall portion 50 to the inner peripheral surface of the inner container 21.
The hole diameter of the heat insulating material 53G substantially coincides with the outer diameter of the partition wall portion 50, and the inner peripheral surface of the heat insulating material 53G and the outer peripheral surface of the partition wall portion 50 are in close contact with each other without a gap.
Further, the upper end surface of the heat insulating material 53G is in close contact with the lower surface of the lid body 30, and the lower end surface is located somewhat below the intermediate position in the height direction of the partition wall 50. In addition, you may change suitably the height of the lower end part of this heat insulating material 53G. For example, it may be closer to the liquid level.
Further, the outer peripheral surface of the heat insulating material 53G is formed with a slight gap with respect to the inner surface of the inner container 21, thereby improving workability such as removal of the lid 30. From the viewpoint of preventing convection of the refrigerant gas, the gap should be small.
Further, a through hole through which the two current leads 91 and 91 are passed is formed in the heat insulating material 53G.
Further, the heat insulating material 53G may be fixedly connected to one or both of the partition wall 50 and the lid 30 and integrally connected.

With this structure, the partition wall part 50G can shield the low-temperature transmission part 43 and the heat exchanger 44 of the refrigerator 40 from the convection refrigerant gas from the periphery and from above, and from the lower side of the partition wall part 50 to the inside. Since the incoming refrigerant gas is mainly cooled and returned to the liquid refrigerant, the convection of the refrigerant gas hardly occurs, and a small convection mainly occurs between the liquid surface and the heat exchanger 44. Therefore, the required cooling capacity can be reduced, the refrigerator 40 can be downsized, and the power consumption of the refrigerator 40 can be reduced.
Further, since the partition wall portion 50G is not in contact with or in close contact with the low temperature transfer portion 43 and the heat exchanger 44, it is possible to efficiently cool the refrigerant gas over the entire surfaces of the low temperature transfer portion 43 and the heat exchanger 44. is there.
Further, since the heat insulating material 53G fills the entire region below the lid body 30, the refrigerant gas reaching the lower surface of the lid body 30 is reduced as much as possible, and the rise in the refrigerant gas temperature is effectively suppressed. Moreover, since the heat insulating material 53G is made of a heat insulating material, it is possible to effectively prevent heat from entering from the lid 30. Thereby, generation | occurrence | production of the convection of refrigerant | coolant gas can be suppressed effectively, and it becomes possible to cool refrigerant gas effectively. For this reason, the refrigerator 40 can be downsized. Further, since the heat insulating material 53G fills the convection generation space of the refrigerant gas over a wide range, it is possible to effectively prevent convection.

[Others]
In addition, the partition parts 50 to 50G described above can be applied to a refrigerator in which the heat exchanger 44 is not provided in the low temperature transmission part 43. In that case, it is desirable that the bottom surface height of the low-temperature transmission unit 43 of the refrigerator 40 is close to the upper limit height of the liquid surface 61 of the liquid refrigerant 60 and somewhat above.
Moreover, the refrigerator 40 mentioned above can also utilize other cold storage type refrigerators other than freezer GM refrigerator, and refrigerators other than a cold storage type.
Further, the object to be cooled by the cryostat 10 to 10G as the cooling container described above is not limited to the superconducting coil but can be any other superconducting device.

[Performance comparison]
FIG. 10 shows the temperature change (in degrees Celsius) of the refrigerant gas temperature Th1, the liquid refrigerant temperature Th2, and the surface temperature Th3 of the heat exchanger 44 in the refrigerant container 20 in the cryostat 10X of the comparative example (hereinafter referred to as the cryostat of FIG. 2). FIG. 11 is a diagram showing a change Ph of the internal pressure, and FIG. 11 shows the refrigerant gas temperature Tj1, the liquid refrigerant liquid surface temperature Tj2, the surface of the heat exchanger 44 in the refrigerant container 20 in the cryostat 10 (referred to as the cryostat in FIG. 1). It is the diagram which showed the temperature change (Celsius) of temperature Tj3, and the change Pj of internal pressure. As another example to which the invention is applied, a cryostat 10G shown in FIG. 9 is prepared, and the temperature change of the refrigerant gas temperature Tk1, the liquid refrigerant liquid surface temperature Tk2, and the surface temperature Tk3 of the heat exchanger 44 in the refrigerant container 20 due to this is prepared. A diagram of (Celsius) and internal pressure change Pk is shown in FIG. These cryostats have the same measurement position for each temperature in the apparatus, and the refrigerant gas pressures Ph1, Pj1, and Pk1 are measured at the same position in the tank.
In addition, the measurement position of the refrigerant gas temperature in each of the cryostats 10, 10X, and 10G is a position between the cooling unit and the lead wire 91, and the height is just below the heat insulating material 53G shown in FIG. It is height.

As shown in FIG. 10, in the cryostat of FIG. 2, the temperature of the refrigerant gas is similarly cooled while maintaining a difference of about +10 degrees following the temperature change of the liquid refrigerant, but the cryostat of FIG. In the cryostat of FIG. 9, as shown in FIGS. 11 and 12, the liquid refrigerant is slowly cooled, whereas the refrigerant gas is cooled only at the beginning, and the temperature does not advance from the middle but rather rises gradually. You can see it happening.
That is, in the cryostat of FIG. 2, convection of the refrigerant gas is generated and cooling is performed to the refrigerant gas away from the refrigerator 40, and no convection of the refrigerant gas is generated in the cryostat of FIG. 1 and the cryostat of FIG. It was observed that the refrigerant gas was not cooled in a place away from the machine 40 and the refrigerant gas temperature started to rise.
That is, in the cryostat 10, the temperature of the liquid refrigerant is normally lowered, so that the cooling of the refrigerant gas outside the partition wall portion 50 does not proceed, but the refrigerant gas is appropriately cooled in the partition wall portion 50 and the liquid refrigerant. You can see that it has been returned to.
Further, when the refrigerant gas temperature is compared between the cryostat of FIG. 1 and the cryostat of FIG. 9, the temperature difference of the cryostat of FIG. 9 is larger than that of the liquid refrigerant and the heat exchanger, and the rate of temperature increase is also slightly higher. It is high. That is, in the cryostat of FIG. 9, the partition wall portion 50G includes the heat insulating material 53G (see FIG. 9).
The convection of the refrigerant gas is more effectively suppressed, and the refrigerant gas temperature tends to rise in a place away from the refrigerator 40, while the cooling unit of the refrigerator 40 cools the liquid refrigerant more efficiently. It was observed that it was going.
Further, in the cryostat of FIG. 1, the liquid refrigerant is efficiently cooled compared to the cryostat of FIG. 2, so that the liquefaction of the refrigerant gas proceeds and the pressure of the refrigerant gas efficiently decreases with time. Since the liquid refrigerant was cooled more efficiently, the refrigerant gas pressure was observed to decrease more remarkably.

10, 10A, 10B, 10C, 10D, 10E, 10F, 10G Cryostat (cooling vessel)
20 Refrigerant container 30 Lid 40 Refrigerator 43 Low temperature transmission part (cooling part)
44 Heat exchanger (cooling part)
50, 50A, 50B, 50C, 50D, 50E, 50F Partition part 51 Top plate part 52, 52C Side wall part 52D Side wall part 53G Thermal insulation material 54C Thermal insulation block 55D Bottom plate part 60 Liquid refrigerant 61 Liquid surface 90 Superconducting coil (superconducting equipment)
91,91 Current lead

Claims (9)

A refrigerant container having an inner container and an outer container, vacuum-insulated between them and having an open top;
A lid capable of closing the opening of the refrigerant container;
A refrigerator supported by the lid;
With
Liquid refrigerant is contained in the inner container of the refrigerant container,
The refrigerator passes through the lid,
The cooling unit of the refrigerator is supported drooping above the liquid refrigerant level in the inner container,
A cooling container, comprising a partition wall part that shields the hanging cooling part from the convection refrigerant gas from the periphery and above in the inner container.   The cooling container according to claim 1, wherein the partition wall has a side wall fixed to the refrigerator or the lid and covering the periphery of the cooling unit.   The cooling container according to claim 2, wherein the partition wall has a top plate that covers the cooling unit.   3. The cooling according to claim 2, wherein an upper end portion of the side wall portion is in contact with a lower surface of the lid body, and surrounds and surrounds the cooling portion by cooperation of the side wall portion and the lid body. container.   The cooling container according to any one of claims 1 to 4, wherein the cooling unit of the refrigerator is filled with a heat insulating material up to a range reaching the inner wall of the inner container.   The cooling container according to claim 5, wherein the heat insulating material is fixed to the lid body or the partition wall.   5. The cooling container according to claim 2, wherein the side wall of the partition wall has a shape that increases in diameter as it goes downward.   The cooling container according to any one of claims 1 to 7, wherein the liquid refrigerant is liquid nitrogen.   The cooling container according to any one of claims 1 to 8, wherein a current lead for energizing the superconducting device is provided through the lid.

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