JPH0633855B2 - Liquid helium storage equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid helium storage device.

<< Prior Art >> In recent years, liquid helium has been actively used as a means for generating extremely low temperatures, but liquid helium is a valuable resource, and most of Japan relies on imports.

Generally, liquid helium is packed in a container of 8 × 8 × 40 feet and transported and stored.

However, since the boiling point of liquid helium is 4.2 K, which is extremely low, a heat-insulated storage container is required, but it cannot be completely insulated and vaporizes in the storage container, causing gas pressure in the storage container to rise. Becomes higher. In addition, since liquid helium has a critical temperature of 5.1 K and a critical pressure of 2.3 atm, it has a property of easily becoming a supercritical state in a closed container.
In the supercritical state, it is difficult to take out the liquid as a liquid. Therefore, conventionally, a relief valve is used to take out the vaporized gas from the storage container to the outside so that the pressure in the storage container does not become high.

<Problems to be Solved> In the conventional liquid helium storage device described above, since the helium gas was released by the relief valve, there was a problem that the economical disadvantage was great.

It is also possible to reliquefy the helium gas taken out from the relief valve by a cooling device, but in this case, the piping between the cooling device and the liquid helium storage container must have a high-performance heat insulating structure. In addition, there is a problem that the reliquefaction efficiency is poor because the piping equipment becomes expensive and the complete insulation structure cannot be expected.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a storage device capable of reliquefying helium gas with a simple facility and storing it in a storage container.

<< Means for Solving the Problem >> In order to achieve the above object, the present invention is configured such that a container is constituted by a heat insulating container having a triple structure, the inside of an intermediate container is divided into two, and one compartment of this intermediate container is divided. In addition to accommodating a liquid helium storage container in the other compartment, liquid nitrogen is stored in the other compartment, and vacuum insulation is provided between the outer container and the intermediate container and between the intermediate container and the liquid helium storage container, and the container has a cryogenic temperature. It is characterized in that the refrigerator is arranged and fixed such that its cold heat generating portion faces the gas layer in the liquid helium storage container.

<< Operation >> In the present invention, the container is constituted by a heat insulating container having a triple structure,
The interior of the intermediate container is divided into two, one compartment of the intermediate container accommodates the liquid helium storage container, the other compartment stores liquid nitrogen, and the space between the outer container and the intermediate container, and Since the intermediate container and the liquid helium storage container are vacuum-insulated, and the cryogenic refrigerator is arranged and fixed in the container with its cold heat generating portion facing the gas layer in the liquid helium storage container, the wall of the intermediate container is fixed. The body acts as a shield plate for the temperature of liquid nitrogen, and effectively suppresses the entry of external heat into the liquid helium storage container. In addition, since helium gas is reliquefied without leaving the liquid helium storage container that is a heat-insulating container, there is no need for piping for guiding the extracted gas to the cooling device and piping from the cooling device to the liquid helium storage container. The device can be simplified, and the reliquefied liquid helium is not affected by external heat, so that the reliquefaction efficiency can be increased.

<< Examples >> The drawings are conceptual views showing examples of the present invention.

This liquid helium storage device consists of a container (1) with a heat insulating structure and a cryogenic refrigerator installed in this container (1).
It is composed of (2) and.

This container (1) is made up of a triple-structured heat-insulating closed container, and the inside of the intermediate container (3) is divided into two, and one compartment (4) contains the liquid helium storage container (5). In addition, liquid nitrogen is stored in the other compartment (6). Therefore, the wall of the intermediate container (3) acts as a shield plate of 78K which is the boiling temperature of liquid nitrogen. Then, heat insulating plates are laminated and arranged in the space (7) between the intermediate container (3) and the liquid helium storage container (5) and in the space (9) between the intermediate container (3) and the outer container (8). By doing so, the heat input of radiant heat is prevented, and both spaces (7) and (9) are formed into a vacuum so as to prevent heat transfer due to convection.

Further, the relief layer (11) is connected to the gas layer (10) formed in the upper part of the liquid helium storage container (5) so that the gas pressure in the gas layer (10) is 15 psi (1.05 Kg / 1.0 g / g). cm ² )
The settings are as follows.

Then, in this container (1), a cryogenic cooler (2) using helium as a refrigerant, in a state where its cold heat generating part (12) is thrust into the gas layer (10) of the liquid helium storage container (5) It is arranged. Reference numeral (13) is a compressor unit of the cryogenic cooler (2),
(14) is the power source of the cryocooler (2), (15) is the cryocooler (2)
Power switch.

In the liquid helium storage device configured as described above, external heat gradually tries to enter the container (1) during transportation or storage, but the wall of the intermediate container (3) acts as a shield plate for liquid nitrogen temperature. Since it acts, external heat is prevented from entering the liquid helium storage container (5), and the cryogenic refrigerator (2) is placed in the gas layer (10) in the liquid helium storage container (5).
Since the cold heat generating part (12) of (1) faces, the helium gas in the gas layer (10) comes into contact with the cold heat generating part (12) and is reliquefied. Therefore, the gas pressure in the gas layer (10) does not rise, the helium gas is not released to the outside from the relief valve (11), and wasteful consumption of helium is eliminated.

Further, since the cryogenic refrigerator (2) penetrates the wall surface of the intermediate container (3), the intermediate container (3) itself is cooled by the cryogenic refrigerator (3), so liquid nitrogen Not to mention the evaporation suppression of
The vaporized nitrogen gas can be reliquefied, and the entry of external heat into the liquid helium storage container (5) can be stably prevented for a long period of time.

<< Effect >> In the present invention, the container is configured by a heat insulating container having a triple structure,
The interior of the intermediate container is divided into two, one compartment of the intermediate container accommodates the liquid helium storage container, the other compartment stores liquid nitrogen, and the space between the outer container and the intermediate container, and The intermediate container and the liquid helium storage container are vacuum-insulated, and the cryogenic refrigerator is arranged and fixed in the container so that the cold heat generating part faces the gas layer in the liquid helium storage container. It acts as a shield plate for the nitrogen temperature, prevents heat from entering the liquid helium storage container from the outside, and can suppress vaporization of liquid helium in the liquid helium storage container. The vaporized helium gas can contact the cold heat generation part of the cryogenic refrigerator to be reliquefied and does not release helium to the outside. Therefore, helium, which is a valuable resource, can be effectively used. After which it can be, it is previously stored for long it is possible to eliminate the ullage of liquid helium.

Further, since the vaporized helium gas can be reliquefied without being taken out of the liquid helium storage container, a pipe for guiding the taken gas to the cooler and a pipe from the cooler to the liquid helium storage container are not required, and the liquid In addition to simplifying the helium storage device, reliquefied helium is not affected by external heat, and reliquefaction efficiency can be increased.

Further, since the cold heat generating portion of the cryogenic refrigerator is located in the liquid helium storage container, the internal pressure of the liquid helium storage container can be kept low. As a result, flash loss and reduced pressure loss can be reduced when helium is taken out, helium can always be pumped out in a liquid state, and liquid helium transfer efficiency can be increased when liquid helium is transferred.

[Brief description of drawings]

The drawings are conceptual diagrams showing an embodiment of the present invention. 1 ... Container, 2 ... Cryogenic refrigerator, 3 ... Intermediate container, 4 ... One compartment of intermediate container, 5 ... Liquid helium storage container, 6 ... Other compartment of intermediate container, 8 …… External container, 10 …… Gas layer, 12 …… Cold heat generation part of cryogenic refrigerator.

Claims (1)

[Claims] 1. A container which is transported or stored with liquid helium stored therein, wherein the container (1) comprises a heat insulating container having a triple structure, and an intermediate container.
The inside of (3) is divided into two, and the liquid helium storage container (5) is accommodated in one compartment (4) of the intermediate container (3), and the liquid nitrogen is stored in the other compartment (6). Store and store (8)
And the intermediate container (3) and between the intermediate container (3) and the liquid helium storage container (5) are vacuum-insulated, and the cryogenic refrigerator (2) is installed in the container (1) as a cold heat generating part ( A liquid helium storage device, characterized in that the liquid helium storage container (5) is arranged and fixed so as to face the gas layer (10).