JPS6349917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cryogenic apparatus having a cryogenic vessel and an open tube connected to a room-temperature vacuum vessel surrounding the cryogenic vessel.

In conventional cryogenic devices, particularly those consisting of a cryogenic vessel containing a superconducting magnet, the open tube is generally mounted upwardly at the top of the vessel. However, in cryogenic equipment where there is no room to install piping above the container, it is necessary to connect the container and a room-temperature vacuum container that surrounds the container with an insulating space in between using horizontal or near-horizontal piping.
FIG. 1 shows a cryogenic apparatus of such a configuration.
2 is a cryogenic container containing cryogenic refrigerant liquid helium 4 and a superconducting magnet 5, 1 is a vacuum container surrounding it, and between them is a radiation shield 3 and a high vacuum for suppressing heat radiation. A heat insulating space is formed using laminated heat insulating materials, etc. Although the cryogenic container 2 is omitted in the drawing, it has excellent heat insulation properties and can withstand high loads, making it possible to connect the vacuum container 1 to the vacuum container 2.
Fixed. Gaseous helium is placed above the liquid helium 4, and it is formed of an open tube 7 that releases the gaseous helium to the outside when rapid evaporation occurs inside, and a rupture plate 8 that serves as a safety valve at the end on the room temperature side. A safety device 6 is piped from the cryogenic container 2 to the vacuum container 1. In such a configuration, there is a large temperature difference between both ends of the open tube 7 (- on the cryogenic container side).
It was experimentally confirmed that natural convection of gas occurs inside the open tube because the temperature is 269℃ (20℃ on the vacuum vessel side). As a result, warm helium gas moves from the vacuum vessel side to the cryogenic vessel side, thereby transporting heat. This heat increases the amount of evaporation of the liquid helium 4, and the loss during refrigeration becomes too large to be ignored. In particular, the larger the diameter of the open tube 7, the stronger the natural convection and the greater the heat loss. In addition, moving objects such as cryogenic equipment that houses superconducting magnets for magnetic levitation vehicles may oscillate due to acceleration or deceleration.
If liquid helium 4 is concentrated on the open tube side,
Liquid helium 4 flows into the open tube 7
The amount of evaporation of liquid helium increases by absorbing heat from the high temperature of the liquid helium. As a result, there was a drawback that the loss of refrigeration could no longer be ignored.

An object of the present invention is to provide a cryogenic device in which the amount of evaporation of liquid helium is small.

A feature of the present invention is that a destruction plate is attached to both ends of the emergency release pipe, and the inside is kept in a vacuum, and the plate is inserted into the open pipe of the safety device with a gap seal provided, thereby preventing natural convection of helium gas. This prevents liquid helium from entering the open tube, thereby reducing the amount of liquid helium evaporated.

Embodiments of the present invention will be described below with reference to the drawings.
2 and 3 are a sectional view showing one embodiment of the present invention and an enlarged sectional view of a safety device. The emergency release pipe 11 has a low-temperature rupture plate 10 on the low-temperature side and a normal-temperature rupture plate 9 on the normal-temperature side, and is inserted into the open pipe 7.
The inside of the emergency discharge pipe 11 is evacuated by a vacuum pump and sealed off by a valve. At this time, the gap between the opening tube 7 and the emergency release tube 11 is made very narrow to seal the gap and prevent liquid helium 4 from entering the gap. FIG. 4 is an enlarged sectional view of a safety device showing another embodiment of the present invention. The gap between the opening tube 7 and the emergency release tube 11 is used as a threaded portion 12 to seal the gap, thereby obtaining the same effect as the previous embodiment. The emergency release tube 11 is attached to the vacuum container 1 at normal temperature using a screw 14 via a vacuum-resistant flexible tube 13. FIG. 5 is also an enlarged sectional view of a safety device showing another embodiment of the present invention. Here, the gap seal is tapered to obtain the same effect as in the previous embodiment. Further, in this embodiment, the forced destruction device 16 is installed so that when the destruction plate 10 on the low temperature side is operated and destroyed, the destruction plate 9 on the room temperature side is immediately activated and destroyed. 6a and 6b show specific examples of this forced destruction device, which are attached to the flange 17. To explain the principle of operation, as shown in FIG. 7, before the low-temperature breakdown plate operates, the normal-temperature breakdown plate 9 has a shape as shown by a solid line. However, when the cold destruction plate operates, the vacuum inside the emergency release pipe 11 is broken, and the cold destruction plate 9 comes into contact with the forced destruction device 16 as shown by the dotted line, and is automatically destroyed. In this way,
It is possible to eliminate the natural convection space for helium gas and completely eliminate the intrusion of liquid helium into the open pipe portion, thereby eliminating an increase in the amount of evaporation of liquid helium. Moreover, it can also fully serve as an emergency release pipe.

As described above, according to the present invention, the amount of evaporation of liquid helium can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional cryogenic apparatus, FIG. 2 is a diagram showing an embodiment of the cryogenic apparatus of the present invention,
Figure 3 is an enlarged sectional view of the safety device in Figure 2;
4 and 5 are enlarged sectional views of a safety device in another example of the cryogenic apparatus of the present invention, and FIG.
FIG. 7 is a diagram illustrating the operation of the room-temperature rupture plate in FIG. 5, showing a specific example of the forced rupture device in the figure. 1... Vacuum container, 2... Cryogenic container, 3... Radiation shield, 4... Liquid helium, 5... Superconducting magnet, 6... Safety device, 7... Open tube, 8... Breaking plate, 9 ...Room temperature rupture plate, 10...Low temperature rupture plate,
11...Emergency release pipe, 16...Forced destruction device.

Claims (1)

[Scope of Claims] 1. A cryogenic container for storing a cryogenic refrigerant, a vacuum container surrounding the cryogenic container via a heat insulating space,
In a cryogenic device having a safety device connected between the cryogenic container and the vacuum container, an emergency release tube with break plates attached to both ends and whose interior is kept in a vacuum is inserted into the open tube of the safety device with a gap. A cryogenic device characterized by being inserted so as to provide a seal. 2. A cryogenic device according to claim 1, characterized in that the gap seal is screw-shaped. 3. A cryogenic device according to claim 1, characterized in that the gap seal is tapered. 4. In any one of claims 1 to 3, the rupture plate on the vacuum vessel side is forcibly destroyed immediately after the rupture plate on the cryogenic vessel side operates. A cryogenic device characterized by having a device attached thereto.