JPS5984481A - Device for preventing reverse pressure of low temperature container - Google Patents

Abstract

PURPOSE:To prevent the damage due to the outer pressure of a low temperature container by a method wherein a check value is provided between a heat insulation vacuum bath for an outer bath and the low temperature container for an inner bath, and the heat insulation bath is always evacuated at the time of evacuating the low temperature container. CONSTITUTION:When a superconductive coil 1 is used in liquid He, the heat insulation vacuum bath 4 is evacuated through a pump 10 by opening a valve 9. Since the pressure of the inner bath low temperature container 2 is high, the check valve 3 is closed. A valve 8 is opened by closing valves 5 and 6, and thus the inner bath is evacuated. The check valve 3 is closed because of no operation of the container 2 and the bath 4 under the same pressure. Next, the valve 8 is closed, the valve 5 is opened, and then the inner bath is filled with He gas until the pressure thereof becomes atmospheric pressure. The He purity in the inner bath is improved by repeating these operations, the valve 8 is closed, the valves 5 and 6 are opened, thus setting in cooling operation. When the pressure in the vacuum bath 4 becomes higher than the pressure in the inner bath container 2 on account of service interruption, etc., the check valve 3 opens. Thereby, the outer pressure does not apply to the inner bath container 2. Therefore, it causes no deformations and damages of the container 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention (d) relates to a cryogenic container having an adiabatic vacuum chamber, and particularly to a cryogenic container suitable for a liquid helium container or the like.

[Prior art]

Conventionally, in a low-temperature container with an insulated vacuum chamber, the low-temperature container is evacuated to replace gas after the insulated vacuum chamber is evacuated to prevent external pressure from being applied to the low-temperature container in the inner tank.

In this operation, there is a drawback that if the operator makes a mistake in the operating procedure, external pressure may be applied to the internal cryogenic container, causing damage to the internal cryogenic container.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reverse pressure prevention device for a cryogenic container, which prevents external pressure from being applied to the private cryogenic container even if the private cryogenic container is evacuated while the insulated vacuum chamber is at atmospheric pressure. be.

[Summary of the invention]

The main point of the present invention is that in a cryogenic container having an insulated vacuum chamber,
When the outer tank's vacuum insulation tank is at atmospheric pressure, the inner tank's cryogenic container is evacuated (J) to prevent the inner tank's cryogenic container from being damaged by external pressure. A check valve is provided between the low-temperature containers in the inner tank so that whenever the low-temperature containers in the inner tank are evacuated, the adiabatic vacuum tank in the outer tank is always evacuated.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

Since the Super Electric Coil 1 is used in cryogenic liquid helium, preparatory operations such as evacuation of the insulated vacuum chamber and replacement of scum in the internal cryogenic container are required.

The basic operations and operation of the check valve 3 according to the present invention will be explained below.

■ Operate the vacuum pump 10 and open the valve 9 to evacuate the insulated vacuum chamber 4. At this time, the check valve 3 is the inner tank 11! , Warm container (1!L Because the pressure is high, only the insulated vacuum chamber is evacuated in the closed state.

(2) Next, the helium gas supply valve 5 and recovery valve 6 are closed, and the inner tank replacement valve 8 is opened to exhaust the inner tank. At this time, the check valve 3 remains closed because the internal cryogenic container 2 and the external insulation vacuum chamber 4 do not operate at the same pressure.

(2) Next, close the internal replacement valve 8, open the helium gas supply pulp 5, and fill the internal tank with helium gas until the pressure reaches atmospheric pressure.

By repeating the operations from (1) to (2), the helium gas in the inner tank is sufficiently removed (in (-), the replacement valve 8 is closed, the helium gas supply pulp 5 and recovery valve 6 are opened, and cooling operation begins.

As mentioned above, during normal operation, the check valve 3 is always closed, but due to a power outage etc. during the above operations
When the pressure becomes higher than the pressure in the inner cryogenic container 2, the check valve 3 opens, so that no external pressure is applied to the inner cryogenic container 2, and the wall thickness of the inner tank can be made thinner. Even if there is a mistake in operation, external pressure will not be applied to the inner cryogenic container.

In the figure, 71d is the turtle flow lead.

〔Effect of the invention〕

According to the present invention, since no external pressure is applied to the inner cryogenic container, a structure that can withstand only internal pressure can be used.

Additionally, during operation, the inner cryogenic container was deformed due to external pressure.

This prevents damage and is effective for operational measurements.

[Brief explanation of drawings]

The figure is a system diagram of a test container for superconducting coils according to an embodiment of the present invention. 1... Superconducting coil, 2... Inner low temperature vessel, 3...
・Return check Cνj・-1

Claims (1)

[Claims] 1. In a low-temperature container built into an insulated vacuum chamber, a back pressure prevention valve is installed between the low-temperature container and the insulated Mashiba 4ff so that no external pressure is applied to the low-temperature container when the low-temperature container is evacuated. A reverse pressure prevention device for a low-temperature container, which is characterized by being installed.