JPS624309A - Cryogenic apparatus - Google Patents

Abstract

PURPOSE:To save energy by a method wherein a gravitational circulation type cooling apparatus is employed as a cooling apparatus for an object to be cooled such as a superconducting coil and a coolant is forcibly make to flow through an exclusive pre-cooling pipe at the time of pre-cooling only. CONSTITUTION:Liquid helium P, contained in a liquid helium container 17, is pumped out from the bottom of the container 17 into a coolant outlet part 21 by gravity. The helium P reaches the lowest end part of the direction of the gravity while being kept at that temperature. The helium P, which reaches a vaporizing part 22, exchanges heat with a superconducting coil 1 through a heat equalizing plate 11 and is vaporized. The vaporized coolant ascends meandering through the vaporizing part 22 and is fed back above the free liquid surface in the container 17. On the other hand, when the coil 1 is pre- cooled from a normal temperature to an intermediate temperature, a compressor is attached to a supply port 52 of a pre-cooling pipe 51 and liquid helium is supplied from the port 52. Then the coil 1 is cooled rapidly. With this constitution, energy can be saved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cryogenic device such as a superconducting magnet, and particularly to a cryogenic device using a natural circulation cooling method.

[Technical background of the invention and its problems]

In a superconducting magnet device, it is necessary to cool the superconducting coil to an extremely low temperature of, for example, about 4 ℃. Conventionally, superconducting coils have been cooled by immersing them in a liquid helium reservoir. However, this method has drawbacks such as requiring a large space for the helium reservoir, requiring a large amount of helium to be stored, and requiring a complicated manufacturing process for the helium reservoir.

In contrast, a method has been proposed in which a refrigerant such as liquid helium is forced to circulate in a refrigerant circulation path that is thermally connected to the superconducting coil to cool the superconducting coil. However, since this method requires equipment for forced circulation of the refrigerant, it has been difficult to apply it to small superconducting coils. In addition, it is necessary to constantly force the refrigerant to circulate not only during pre-cooling but also after the superconducting coil has been cooled to an extremely low temperature, which places a heavy burden on the refrigerant circulation power source such as a compressor.

[Purpose of the invention]

The present invention was developed in view of the above circumstances, and its purpose is to reduce the space and helium storage required for cooling objects such as superconducting coils, and to reduce manufacturing costs. The object of the present invention is to provide a cryogenic device that can be easily applied to small superconducting coils.

[Summary of the Invention] The gist of the present invention is to use a so-called natural fall circulation type cooling device as a cooling device for cooling objects to be cooled such as superconducting coils, and to forcibly flow a refrigerant through a pipe dedicated to precooling during precooling. There is a particular thing.

That is, the present invention provides a cryogenic apparatus that includes an object to be cooled and a cooling device that cools the object to an extremely low temperature. It consists of a liquid reservoir and a vaporizer that constitutes a cooling cycle, and the piping is installed in a closed loop via the liquid reservoir, and at least the refrigerant from the vaporizer to the liquid reservoir is directed upward in the direction of gravity. a refrigerant circulation path configured to proceed to the object to be cooled; a means for thermally connecting the vaporizing section to the object to be cooled; and a refrigerant circulation path in which the object to be cooled is cooled by forcing the refrigerant to flow during precooling. A pre-cooling pipe is provided which is independent of the pipe.

〔Effect of the invention〕

According to the present invention, since a natural fall circulation method is adopted in which the circulating power of the refrigerant is obtained by utilizing the density difference between the liquefied refrigerant and the vaporized refrigerant, the circulating power of the refrigerant such as a compressor is used except during pre-cooling. You don't need the means to get it. In other words, once the object to be cooled, such as the superconducting coil, is cooled to an extremely low temperature (or an intermediate temperature), there is no need for refrigerant circulation power, resulting in energy savings. Further, during pre-cooling, it is sufficient to simply attach a power source such as a compressor for flowing refrigerant to the pre-cooling gas piping, and it is also possible to configure this power source to be externally attached. Therefore, the overall configuration can be simplified, and application to small superconducting coils is also possible.

Furthermore, since the present invention employs a method of cooling the object to be cooled by thermally connecting the refrigerant circulation path and the object to be cooled, there is no need for a liquefied helium reservoir for immersing the object to be cooled. . Therefore, the space required for cooling the object to be cooled and the amount of helium stored can be reduced.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

The figure is a partially cutaway perspective view of a superconducting magnet device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a superconducting coil (object to be cooled) formed in an annular shape, and the coil 1 is cooled to an extremely low temperature by a cooling device 2- that covers the entire outer peripheral surface of the coil.

The cooling device 2- is specifically configured as follows. That is, the outer circumferential surface of the superconducting coil 1 is completely covered by the heat soaking plate 11. The heat equalizing plate 11 has two semi-circular divided bodies 1 made of a good heat conductor such as copper.
Each circumferential end of 1a and 11b is fixed with an insulating bolt 13 via an electrically insulating plate 12. With this configuration, induction heating of the heat equalizing plate 11 due to excitation of the superconducting coil 1 is suppressed. The heat soaking plate 11 and the superconducting coil 1 are integrated using an epoxy resin 14 having a coefficient of thermal expansion similar to that of copper and having excellent thermal conductivity for the purpose of improving thermal adhesion. In addition, the soaking plate 11
A plurality of holes 15 are bored through the epoxy resin 14 on both sides of the heat equalizing plate 11. Therefore, the heat soaking plate 11 and the epoxy resin 14 are designed to thermally shrink together.

Thus, the superconducting coil 1 is cooled via the heat soaking plate 11 by a group of main bodies of the cooling device of the natural fall circulation type. The cooling device main body 16 includes a liquid helium tank (liquid reservoir) 17 installed above the superconducting coil 1 and a refrigerant flow pipe 18 that allows a refrigerant to flow from the bottom of the liquid helium tank 17 to the same side. It is configured. Liquid helium tank 17
contains liquid helium P. Two lines of refrigerant flow pipes 18 are provided so as to extend along the outer surfaces of the two divided bodies 11a, 11b of the heat equalizing plate 11, and each line runs from the bottom of the liquid helium tank 17 to the outer periphery of the heat equalizing plate 11. It is composed of a refrigerant pumping part 21 that advances downward in the direction of gravity, and a vaporizing part 22 that is guided upward in the direction of gravity from the lowest end of the refrigerant pumping part 21 onto the free liquid surface of the liquid helium tank 17. ing.

The refrigerant pumping part 21 is a heat insulating spacer 23 with poor thermal conductivity.
It is fixed to the heat equalizing plate 11 via the heat equalizing plate 11 and is thermally insulated from the heat equalizing plate 11. Further, the vaporizing section 22 is embedded in the epoxy resin 14 so as to be in direct contact with the heat equalizing plate 11, and is fixed to the heat equalizing plate 11 at a predetermined portion or over the entire length by a method such as soldering. has been done. Furthermore, the vaporization section 2
2 is composed of a plurality of branch pipes 31 that are provided in close contact with the circumferential surface of the heat equalizing plate 11 and extend in the circumferential direction, and headers 32 and 33 that commonly connect both ends of these branch pipes 31.

Therefore, the liquid helium P pumped out from the liquid helium tank 17 passes through the refrigerant pumping part 21 and reaches the header 33 at the lower end, and in the process of ascending from the header 33 through each branch pipe 31, it exchanges heat with the superconducting coil 1. vaporized. The vaporized refrigerant is collected in the header section 32 at the upper end and is passed through the return pipe 34.
The liquid helium is returned to the liquid helium tank 17 via.

On the other hand, on the outer peripheral surface (epoxy resin 14) of the heat soaking plate 11,
A precooling pipe 51 independent of the refrigerant circulation path 18 is provided. This pre-cooling pipe 51 includes a supply boat 52
Cold gas or liquid is sent from the coil 1, and the coil 1 is cooled to an intermediate temperature by the flow of the gas or liquid. Then, the gas or steam heated by the coil 1 is transferred to the exhaust boat 5.
It is supposed to be released from 3.

The above superconducting coil 1 and cooling device 2- are, for example, 5
It is surrounded by a radiation shield 24 of about 0 to 80 degrees, and the whole is housed inside a vacuum container 25 to block heat from entering from the outside.

In the superconducting magnet device according to this embodiment configured as described above, the superconducting coil 1, which is the object to be cooled, is cooled in the following manner.

That is, the liquid helium P contained in the liquid helium tank 17
is pumped out from the bottom of the liquid helium tank 17 to the refrigerant pumping section 21 by gravity. Since the refrigerant pumping part 21 is thermally insulated from the heat equalizing plate 11, the liquid helium P is
It reaches the lowest end in the gravity direction at the same temperature. Furthermore, the liquid helium P that has reached the vaporization section 22 is
The superconducting coil 1 exchanges heat with the superconducting coil 1 through the superconducting coil 1, and is vaporized.

The vaporized refrigerant rises in a meandering manner through the vaporization section 22 and returns to the free liquid surface of the liquid helium tank 17 . The refrigerant gas on the free liquid surface is liquefied by a liquefaction device (not shown) and pumped out from the refrigerant pumping section 21 again. Note that this liquefaction device may not be provided, and in this case, liquid helium will be replenished.

In this refrigeration cycle, a difference in the density of the refrigerant occurs between the inside of the refrigerant pumping section 21 and the inside of the vaporization section 22, so that the circulating power of the refrigerant can be obtained from this density difference. Therefore, this cooling device 12 does not require any particular means for circulating the refrigerant.

On the other hand, when cooling (precooling) the superconducting coil 1 from room temperature to an intermediate temperature, a compressor or the like is attached to the supply boat 52 of the precooling piping 51, and liquid nitrogen or the like is fed from the supply boat 52. Thereby, liquid nitrogen or nitrogen gas is forced to flow into the precooling gas pipe 51, and the superconducting coil 1 can be rapidly cooled by heat exchange via the heat equalizing plate 11. The vaporized nitrogen vapor heated by the coil 1 is discharged from the exhaust boat 53. After the precooling of the coil 1 is completed, the discharge boat 53 is blind-corked, the supply boat 52 is evacuated, and then sealed.

Once the superconducting coil 1 has been cooled to an intermediate temperature, even if the flow of the refrigerant in the pre-cooling pipe 51 is stopped, the superconducting coil 1 will be cooled to an extremely low temperature by the refrigerant circulating in the refrigerant passage 18. Ru. In other words, after cooling to an intermediate temperature, a circulating power source such as a compressor is not required.

In this way, according to this embodiment, the refrigerant can be naturally circulated inside the refrigerant flow pipe 18 without using a device for forced refrigerant circulation except during precooling, so that the overall size of the device can be reduced and the structure can be reduced. It is possible to achieve simplification and also to save energy. Furthermore, since the pre-cooling pipe 51 is provided independently of the refrigerant passage 18, residual nitrogen during pre-cooling does not enter the liquid helium tank 17, thereby preventing trouble with the refrigerator. be able to. In addition, since there is no need for a liquid helium reservoir in which the superconducting coil 1 is immersed,
This has the advantage that the space required for cooling the superconducting coil 1 and the amount of liquid helium stored can be reduced.

Note that the present invention is not limited to the embodiments described above. For example, the refrigerant flowing through the pre-cooling pipe is not limited to liquid nitrogen, but may be a gas as long as it can cool the object to be cooled to a predetermined intermediate temperature.

Further, the refrigerant to be circulated in the refrigerant circulation path is not limited to liquid helium, and can be changed as appropriate depending on the temperature at which the object to be cooled is cooled. Furthermore, the object to be cooled is not limited to superconducting coils, but can be applied to any object that needs to be cooled to an extremely low temperature. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

The figure is a partially cutaway perspective view of a superconducting magnet device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Superconducting coil (cooled body), 2-... Cooling device, 11... Soaking plate, 12... Insulating plate, 14... Epoxy resin, ie-... Cooling device main body, 17 ...Liquid helium tank (liquid reservoir), 18...Refrigerant flow pipe, 21
...Refrigerant pumping part, 22... Vaporization part, 24... Radiation shield, 25... Vacuum container, 31... Branch piping,
32.33...Header, 51...Pre-cooling piping, 52
...Supply boat, 53...Discharge boat, P...Liquid helium.

Claims (4)

[Claims] (1) In a cryogenic apparatus comprising an object to be cooled and a cooling device that cools the object to a cryogenic temperature, the cooling device is a cryogenic liquid installed above the object to be cooled. The refrigerant is composed of a reservoir and a vaporizer that constitutes a cooling cycle, and is installed in a closed loop through the liquid reservoir, and at least the refrigerant from the vaporizer to the liquid reservoir moves upward in the direction of gravity. a refrigerant circuit configured to;
means for thermally connecting the vaporization section to the object to be cooled; and precooling piping that is provided independently of the refrigerant circulation path and forcibly flows a refrigerant during precooling to cool the object to be cooled. A cryogenic device characterized by comprising: (2) The cryogenic device according to claim 1, wherein the object to be cooled is a superconducting coil. (3) As a means for thermally connecting the vaporizing section to the object to be cooled, a heat equalizing plate that contacts the vaporizing section and covers the object to be cooled is used. Cryogenic equipment as described in section. (4) The cryogenic apparatus according to claim 3, wherein the heat equalizing plate is divided into a plurality of parts in the circumferential direction of the object to be cooled, and each part is electrically insulated.