JPH06163251A - Cryogenic vessel - Google Patents

Abstract

PURPOSE:To obtain a simple, small-sized cryogenic vessel of low cost having a thermal anchor wherein an exclusive cooling source is nunecessary. CONSTITUTION:A vessel wherein an inner vessel 11 is surrounded by an outer vessel 12, and a vacuum heat insulation part 13 is formed between both vessels is an object. A thermal anchor 15 having a structure wherein cold storing material 16 is accommodated in a case 17 is installed in the middle part of a heat conduction path (refrigerant introducing port 11b in figure) from the upper part of the inner vessel to a refrigerant liquid accommodation part 11a. The thermal anchor is cooled by using evaporation gas of refrigerant liquid A. Since the heat capacity of the thermal anchor 15 is large and cold is stored therein, permeation of external heat can be prevented without using an exclusive cooling source. When the capacity is sufficient, a radiant heat shielding plate 14 can be cooled by applying the thermal anchor to a cooling source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid storage cryogenic container (cryotat) used for accommodating a superconducting coil together with a refrigerant liquid such as liquid helium and cooling the coil.

[0002]

2. Description of the Related Art An example of a conventional liquid storage type cryogenic container is shown in FIG.
Shown in. This container is a wide-mouthed bucket type, and includes an inner tank 1 for storing liquid helium (hereinafter referred to as LHe),
A vacuum heat insulating section 3 is formed between the outer tanks 2 surrounding this, and further,
A radiant heat shield tank 4 filled with liquid nitrogen (hereinafter referred to as LN ₂ ) is arranged in the vacuum heat insulating portion 3, and this shield tank is connected to the outer periphery near the upper end of the inner tank by a metal having good heat conductivity to thermally connect this portion. It is designed to work as anchor 5.

[0003] thermal anchor 5, maintaining the internal bath temperature in the vicinity of LN ₂ temperatures (77k) at the installation point by cooling with LN _2, the heat intrusion from the outside to flow along the wall material of the inner tank in this part It is provided for the purpose of stopping.

The effect is described in, for example, P of Low Temperature Engineering Handbook (published on September 15, 1982, Uchida Otsuruho Shinsha).
288-P289, P583. In the report, in the case of a wide-mouth stainless steel cryogenic container, the integrated thermal conductivity without a thermal anchor was about 30 W / cm,
The value is about 3.1W when the thermal anchor is taken near 7k.
/ Cm is almost 1/10.

As described above, the thermal anchor plays an important role in preventing heat invasion. However, when the radiation heat shield tank 4 is used as a cooling source as shown in FIG. 3, cold heat is generated when the liquid level of LN ₂ in the tank 4 is lowered. The transmission path becomes longer and the effect diminishes.

Therefore, when a more reliable thermal anchor is required, a dedicated LN ₂ tank 6 independent of the radiant heat shield tank is provided and used as a cooling source.
As shown in Japanese Patent Laid-Open No. 4-116907, a radiant heat shield plate is cooled by a refrigerator and used as a cooling source.

[0007]

If a dedicated LN ₂ tank or a refrigerator is provided to enhance the effect of preventing heat intrusion, the structure of the container becomes complicated, and the cost, maintenance, and maintenance work increase.

Therefore, an object of the present invention is to enhance the effect of preventing external heat from entering without causing such a problem.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a cryogenic container provided with a thermal anchor in the middle of a heat transfer path from an upper part of an inner tank to a refrigerant accommodating portion, in which the thermal anchor is provided. With a structure that contains a cold storage material,
It is cooled by the evaporated refrigerant gas in the inner tank.

The thermal anchor used in the present invention is
It can also be used as a cooling source for the radiant heat shield plate installed between the inner tank and the outer tank.

[0011]

[Function] When the regenerator material is incorporated, the thermal capacity of the thermal anchor increases.

On the other hand, the refrigerant liquid (LHe or L
N ₂ ) always evaporates little by little, and the vaporized gas generated thereby cools the thermal anchor portion on the way to the refrigerant outlet port at the upper end of the inner tank. At this time, the greater the heat capacity of the thermal anchor, the more sensible heat of the vaporized gas is absorbed, so that it is possible to prevent the intrusion of heat from the outside by the cold heat of self-storage without cooling by the LN ₂ tank or the refrigerator. it can.

Further, if there is a surplus in the heat capacity, the stored cold heat can be diverted to other places, so that it is possible to cool the radiant heat shield plate and the like by using the thermal anchor as a cooling source, which is contrary to the conventional case. .

[0014]

FIG. 1 shows a specific example of the cryogenic container of the present invention.

The cryogenic container 10 includes an inner tank 11 for storing a refrigerant liquid A such as LHe and LN ₂ , an outer tank 12 surrounding the inner tank 12, and radiant heat installed in a vacuum heat insulating section 13 between the both tanks. It comprises a shield plate 14 and a thermal anchor 15 provided in the middle of the tank wall from the upper part of the inner tank to the refrigerant liquid storage section.

The inner tank 11 shown here is a refrigerant liquid storage portion 11
A thermal anchor 15 is provided midway in the longitudinal direction of the refrigerant inlet / outlet port 11b in a form in which a cylindrical refrigerant inlet / outlet port 11b is connected to the upper part of a. A superconducting coil (not shown) is incorporated in the inner tank 11 in advance. Depending on the size and use of the coil, the portion 11a may be formed in a hollow ring shape to accommodate the coil concentrically.

The outer tank 12 surrounding the inner tank 11 and the radiant heat shield plate 14 are similar in shape to the inner tank, and the upper wall 12a of the outer tank is connected to the upper end of the refrigerant inlet / outlet port 11b. Also,
The radiant heat shield plate 14 has its upper end connected to a portion of the thermal anchor 15 for cooling by the thermal anchor.

The thermal anchor 15 is made by putting a regenerator material 16 in a case 17 and welding the case to the inner surface (or the outer surface) of the refrigerant inlet / outlet port 11b. The thermal anchor 15 is installed at an appropriate position in consideration of the thermal gradient from the upper end to the lower end of the refrigerant inlet / outlet port. For example, it is provided at a position where a temperature of 80k can be obtained when making an anchor of 80k, and at a position where a temperature of 20k can be obtained when making an anchor of 20k. It is more effective to provide a plurality of anchors having different tethering temperatures.

The regenerator material 16 has a large specific heat (volume specific heat) in this range when it is desired to keep the temperature in the vicinity of 20 to 80 k, and below 20 k, Er ₃ Ni, Ho _1.5 Er _1.5 , which has a large specific heat at extremely low temperature. It is preferable to use Ru or the like. In addition, these cold storage materials are preferably fine particles having a large volume specific surface area in terms of heat exchange properties.

The case 17 may be filled with an inert gas (N ₂ or He) which improves heat transfer.

Further, the thermal anchor 15 is provided with irregularities on the surface in contact with the evaporated gas of the refrigerant, or the fin 1 shown in FIG.
When 8 is attached, the contact area with the evaporative gas is increased and heat exchange is improved.

[0022]

As described above, in the cryogenic container of the present invention, the thermal anchor is provided with the regenerator material for cooling by the evaporative gas of the refrigerant, so that the anchor of the LN ₂ tank, the refrigerator or the like is used. A dedicated cooling source becomes unnecessary, and if there is extra power, the thermal anchor can be used as a cooling source for the radiant heat shield plate.

Therefore, there are effects that the container can be simplified, downsized, the cost can be reduced, and the maintenance labor can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a thermal anchor with fins.

FIG. 3 is a sectional view showing an example of a conventional cryogenic container.

[Explanation of symbols]

1, 11 Inner tank 11a Refrigerant liquid storage section 11b Refrigerant inlet / outlet port 2, 12 Outer tank 12a Upper wall 3, 13 Vacuum heat insulating section 4 Radiant heat shield tank 14 Radiant heat shield plate 5, 15 Thermal anchor 6 LN ₂ tank 16 Cooling material 17 Case 18 fins

Claims (2)

[Claims] 1. A vacuum heat insulation section is provided between an inner tank having a refrigerant liquid outlet at the top and an outer tank surrounding the inner tank, and the refrigerant liquid is stored in the inner tank from the upper portion of the inner tank connected to the outer tank. In a cryogenic container provided with a thermal anchor in the middle of the heat transfer path to the heat exchanger, a pole characterized in that the thermal anchor has a structure containing a regenerator material and is cooled by the evaporated refrigerant gas in the inner tank Cryogenic container. 2. A cryogenic container in which the thermal anchor is used as a cooling source for a radiant heat shield plate installed between an inner tank and an outer tank.