JPS6123673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device for a superconducting magnet,
In particular, the present invention relates to a cooling device for a superconducting magnet, which is provided with a communication pipe connected to an inner tank housing the superconducting magnet from outside the outer tank, which is a vacuum container, for injecting liquid helium or recovering helium gas.

Generally, a superconducting magnet is housed in an inner tank together with liquid helium and cooled to an extremely low temperature, and the inner tank is insulated and supported in a heat-insulating outer tank, which is a vacuum container, to prevent external heat from entering. In addition, a communication pipe for supplying liquid helium for appropriately replenishing liquid helium from the outside into the inner tank is connected to the inner tank by penetrating the wall of the outer tank from the outside, and the liquid helium The helium gas vaporized in the inner tank is configured to be collected or released into the atmosphere by flowing out the helium gas vaporized in the inner tank through a common supply communication pipe or a separate helium gas vent communication pipe arranged in parallel. There is.

By the way, in such a cooling device for a superconducting magnet, if the inner tank is constantly in communication with the outside via the above-mentioned communication pipes for supplying liquid helium and degassing helium, heat from outside the outer tank is transferred through the communication pipes. This will cause the superconducting magnet to enter the inner tank, resulting in a decrease in the cooling performance of the superconducting magnet. For this reason, during operation, etc., the inner tank is sealed off from the outside by closing the communication pipe, and the communication pipe is opened only when supplying liquid helium or venting helium gas, thereby reducing external heat as much as possible. It is necessary to prevent entry into the inner tank. Therefore, it is possible to install a shutoff valve that can be opened and closed in the communication pipe for supplying liquid helium or venting vaporized helium gas, but there are difficulties in the mounting position and structure of the valve itself, and it is necessary to lead it out of the outer tank. If a valve is installed in a piping section that is exposed to heat, external heat will be transmitted from the valve itself and the wall of the piping section outside the outer tank into the piping and enter the inner tank, and the piping section in the vacuum space inside the outer tank will be exposed to external heat. When the valve was installed, there was a problem in that the outside air entered through the outer tank wall penetration part of the valve opening/closing operation part, making it impossible to maintain the vacuum layer in the outer tank.

The present invention was developed in view of the above circumstances, and the inner tank can be sealed off from the outside except when liquid helium is supplied or helium gas is vented, and heat can be prevented from entering from the piping section outside the outer tank. Another object of the present invention is to provide a cooling device for a superconducting magnet that has extremely excellent cooling performance and does not adversely affect the maintenance of the vacuum layer in the outer tank.

In other words, the superconducting magnet cooling device of the present application is
In the vacuum space between the outer tank and the inner tank, which is in the middle of a communication pipe that airtightly penetrates the outer tank wall from the outside and communicates with the inner tank to inject liquid helium or discharge vaporized helium gas. A shutoff valve is provided in an intervening state, and the shutoff valve includes a valve seat disposed within a valve body, a valve body that can be moved into and out of contact with the valve seat, and a valve that is connected to an external outlet side portion of the communication pipe from the valve body. The structure consists of a valve opening/closing control lever that passes through the pipe wall for a long time and is led out to the outside by passing through the pipe wall airtightly at a position outside the wall of the outer tank to prevent external heat from entering and to reduce the vacuum inside the outer tank This allows the layer to be kept under vacuum.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, a superconducting magnet 1 is housed in an inner tank 3 filled with liquid helium. This inner tank 3 is surrounded by a vacuum layer 4 and an outer tank 5 containing a superinsulation heat insulating material (not shown), and is held by a heat insulating support member 6 within the outer tank 5, which is the vacuum container.

A communication pipe 20 is provided that airtightly penetrates the wall of the outer tank 5 from the outside and connects to the inner tank 3.
This communication pipe 20 is used to supply liquid helium from the outside into the inner tank 3, and conversely to extract helium gas vaporized in the inner tank 3 to the outside. Note that this communication pipe 20 may be used exclusively for supplying liquid helium, and the vaporized helium gas may be separately extracted to the outside through a gas recovery communication pipe (not shown) arranged in parallel with the communication pipe 20.

A shutoff valve 7A is provided in the outer tank 5 of the communication pipe 20 so as to be interposed in the space between the inner tank 3 and the vacuum layer 4. In other words, the shutoff valve 7A has one end of the valve body (casing) 7 connected to the inner tank 3 via the inner tank connection side pipe part 8 of the communication pipe 20, and the other end of the valve body (casing) 7 airtightly connects the wall of the outer tank 5 of the communication pipe 20. It is provided in a state where it communicates with the outside via an external lead-out pipe section 9 that penetrates through it. Inside the valve body 7 of the shutoff valve 7A, a valve seat 11 is fixedly installed near one end as shown in FIG. and the valve body 1
0 comes into contact with the valve seat 11 (valve closing) by operating the valve opening/closing operation lever 14, which will be described later. When released from the valve (opening the valve), both pipe parts 8 and 9
It is designed to communicate between the two. Here, the valve opening/closing operation lever 14 has a base end fixed to the back surface of the valve body 10 and has a round rod shape that protrudes long toward the other end, and has a male threaded portion 15 in the middle of the base end. It is screwed into a female threaded boss portion 13 provided within the main body 7 via a rib 12 and is supported in a state where it receives a screw feeding action. Further, the valve opening/closing operation lever 14 is connected to the external outlet side pipe portion 9 of the communication pipe 20 from inside the valve body 7.
It passes through the inner center for a long time, extends straight, penetrates the wall of the bent part which is the piping part outside the outer tank 5 of the external outlet side pipe part 9, and is extended to the outside. That is, the valve opening/closing operation lever 14 is led out of the outer tank 5 through the inside of the external outlet side pipe portion 9 of the communication pipe 20 without directly penetrating the wall of the outer tank 5. A seal seat 16 is formed on the wall of the bent portion of the external outlet side pipe portion 9 through which the valve opening/closing operation lever 14 passes, and a seal 17 such as a packing is inserted into the seal seat 16.
8, the valve opening/closing operation lever 14
It is designed to maintain airtightness of the penetration part. Further, an operating handle 19 is attached to the externally extending end of the valve opening/closing operating lever 14, and by rotating the valve opening/closing operating lever 14 from the outside via this handle, the lever 14 is threaded with the boss portion 13. The valve body 10 can be brought into contact with and separated from the valve seat 11 by the screw feeding action caused by the engagement, thereby opening and closing the valve. Note that lead wires and other piping for supplying power to the superconducting magnet 1 in the inner tank 43 are actually provided passing through the inner and outer tanks, but they are not shown because they are not relevant to the essentials of the present invention. .

In a superconducting magnet cooling device having such a configuration, the outer tank 5 located in the middle of the communication pipe 20
Although the shutoff valve 7A is disposed in the vacuum space between the inner tank 3 and the inner tank 3, the valve opening/closing operation lever 14 extending to the outside through the outside outlet side pipe part 9 of the communication pipe 20 does not work. By rotating the handle 19 from the outside, the valve body 10 can be moved to open and close the valve, thereby communicating or blocking communication between the inner tank connection side pipe section 8 and the external outlet side pipe section 9 of the communication pipe 20. You can Therefore, the inner tank 3 can be completely sealed off from the outside except when supplying liquid helium and degassing vaporized helium.
External heat that passes straight through the communication pipe 20 can be prevented from entering the inner tank 3. Also, the shutoff valve 7
Since A is located in the vacuum space between the outer tank 5 and the inner tank 3 in the middle of the communication pipe 20, the external lead-out pipe part 9
It is possible to prevent the external heat transmitted from the wall of the piping section outside the outer tank from directly invading the inner tank connection side pipe section 8 due to gas convection, etc., and the valve opening/closing operation lever 14, which can be rotated, The outer tank 5 is led out through the outside outlet side pipe part 9 of the communication pipe 20 without penetrating the wall of the tank 5.
There is no possibility that outside air will enter the interior, and the vacuum layer 4 can be maintained in a vacuum. That is, it is possible to reliably prevent external heat from entering into the cooling device due to the valve operating mechanism, thereby improving cooling performance. Moreover, if the intrusion of external heat can be prevented, the time for sealing off the inner tank 3 can be extended accordingly, and the cooling performance can be further improved.

FIG. 3 shows another embodiment of the present invention, in which a safety valve 10a is provided on the valve body 10, and the safety valve 10a is always urged to the left in the figure by a spring 21, and the inner tank is sealed off. During the period (valve body 1
0 is closed) If the pressure in the inner tank exceeds a predetermined value due to some abnormal cause, the internal pressure, that is, the internal pressure inside the inner tank connection side pipe part 8 and the external outlet side pipe part 9. Due to the pressure difference between the inner tank and the inner tank, the inner tank is pushed to the right in the figure against the spring 21 and opened, and the helium gas in the inner tank is released to the outside, thereby reducing the pressure and ensuring safety.

FIG. 4 shows still another embodiment of the present invention, in which a pressure reducing means inside the pipe is provided in order to evacuate the inside of the external outlet side pipe part 9 and reduce the intrusion of external heat due to gas convection. A vacuum tank 22 for connecting a vacuum pump (not shown) and a safety valve 23 are provided to the piping portion of the outlet side pipe section 9 outside the outer tank 5, and also to cut off the external device from the external outlet side pipe section 9. A valve 24 is provided for this purpose. When the inner tank is sealed off, the valve 24 is closed, the vacuum chamber 22 is opened, and the vacuum pump releases the gas inside the external outlet pipe section 9 to create a vacuum. It is possible to prevent the air from entering the cooling device through the inside of the outlet pipe portion 9.

As described above, the present invention provides a vacuum between the outer tank and the inner tank in the middle of the communication pipe that airtightly penetrates the outer tank wall from the outside and injects liquid helium into the inner tank or discharges vaporized helium gas. A shutoff valve is provided interposed in the space, and the shutoff valve is
A valve seat disposed within the valve body, a valve body that can be moved into and out of contact with the valve seat, and a pipe portion that extends from the valve body through an external outlet side pipe portion of the communication pipe at a position outside the outer tank wall. The structure consists of a valve opening/closing control lever that penetrates the wall airtight and can be operated externally, so the inner tank can be sealed off from the outside except when supplying liquid helium or venting helium gas. This provides a cooling device for a superconducting magnet that can prevent heat from entering from the piping section outside the outer tank, and has extremely excellent cooling performance without adversely affecting the vacuum maintenance of the vacuum layer inside the outer tank.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
3 is a sectional view of the essential part showing another embodiment of the present invention, and FIG. 4 is a sectional view of the essential part showing another embodiment of the present invention. 1...Superconducting magnet, 2...Liquid helium, 3...Inner tank, 4...Vacuum layer, 5...Outer tank, 6
...Insulation support member, 7A...Sealing valve, 7...
Valve body (casing), 20... Communication pipe, 8... Inner tank connection side pipe part of the communication pipe, 9... External outlet side pipe part of the communication pipe, 10... Valve body, 11... Valve seat, 12 ……
Rib, 13... Female threaded boss portion, 14... Valve opening/closing operation lever, 15... Male thread, 16... Seal seat, 17... Seal, 18... Holding screw, 19...
...Operation handle, 10a...Safety valve, 21...Spring, 22, 23, 24...Pipe pressure reduction means (22...Vacuum pump, 23...Safety valve, 24...
…valve).

Claims (1)

[Scope of Claims] 1. An inner tank that stores a superconducting magnet together with liquid helium, an outer heat-insulating tank that is a vacuum container that surrounds and insulates and supports this inner tank, and a wall of the outer tank that is airtight from the outside of the outer tank. In a cooling device for a superconducting magnet, the cooling device includes a communication pipe that penetrates the inner tank and injects liquid helium or discharges vaporized helium gas, the vacuum space between the inner tank and the outer tank of the communication pipe. A valve body interposed in the middle of the valve body, a valve seat disposed within the valve body, a valve body that can be moved into and out of contact with the valve seat, and an external outlet side pipe portion of the communication pipe from within the valve body. A superconducting magnet characterized in that a shutoff valve is provided at a position outside the outer tank wall for a long time, and includes a valve opening/closing operation lever that airtightly penetrates the pipe wall and is led out for external operation. cooling system. 2. The shutoff valve automatically opens when the differential pressure between the inner tank connection side pipe of the communication pipe and the external outlet side pipe inside the valve body exceeds a certain level, and the vaporized helium gas in the inner tank flows out to the outside. 2. A cooling device for a superconducting magnet according to claim 1, further comprising a safety valve for reducing the temperature of the superconducting magnet. 3. The communication pipe has an internal pressure reducing means that evacuates the outside outlet side pipe section when the valve body of the shutoff valve is closed to prevent external heat from entering due to gas convection. A cooling device for a superconducting magnet according to scope 1.