JPH0554685B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Description of the Technical Field The present invention provides an inner tank for storing a cryogenic refrigerant for storing and cooling a superconducting electromagnetic coil, an outer tank that adiabatically surrounds the inner tank, and an outer tank. The present invention relates to the structure of a cryogenic container that includes a liquid injection pipe and a recovery pipe that are provided through an inner tank and a cryogenic valve that closes off the inner tank.

(2) Prior art and its problems A conventional cryogenic container will be explained using as an example a cryogenic container that stores liquid helium attached to a superconducting magnet device or the like. Liquid helium is a scarce resource, is expensive, and has a small latent heat of vaporization, so it is important to minimize the amount of heat that enters the inner tank of the cryogenic container that stores liquid helium to suppress evaporation of liquid helium and use it effectively. is desirable. Therefore, in order to reduce the amount of heat intrusion in cryogenic containers, it is necessary to have a double structure in which the inner chamber is housed in an outer chamber with a vacuum inside, or to create an intermediate cooling layer between the inner and outer chambers. Efforts have been made such as using a heat insulating material or using a support device with good thermal insulation properties that is fixed to the outer tank to support the inner tank. In addition, in the liquid injection system piping that sends liquid helium to the inner tank and the recovery system piping that collects evaporated helium gas, if the inner tank is closed at the normal temperature end of the outer tank side, the vibration of the liquid helium will cause the liquid to drop. Since heat intrusion into the inner tank occurs due to helium gas jumping into the piping and convection of helium gas in the piping, a low temperature valve that can be shut off at the low temperature section is installed on the above piping to reduce the amount of heat intrusion into the inner tank. I try to suppress it as much as possible. In particular, when a small refrigerator is attached and the superconducting magnet is operated continuously, such as on-board superconducting magnets in floating trains,
The structure described above is important.

FIG. 2 shows the configuration of a cryogenic container having the above structure. The inner tank 1 is insulated and held inside the outer tank 2, and can store liquid helium 3, which is a refrigerant.
Liquid helium is stored in the inner tank 1 through the liquid injection pipe 4, and the helium gas evaporated in the inner tank 1 is stored in the recovery pipe 5.
more will be recovered. 6 and 7 are low temperature valves that close off the inner tank in the low temperature section. Valves 8 and 9 are inlet and outlet valves for liquid injection and recovery, and shut off each system in the room temperature section. Note that the valves 8 and 9 may not be directly attached to the device, but may be installed at other locations. A safety valve 10 is provided for the safety of the piping system. In addition, piping connected to the superconducting magnet device, heat shield plates, various ports, sensors, etc. are also installed, but they are omitted to avoid complication of explanation.

In the cryogenic container described above, when the inner tank is closed off with the cryogenic valve, the liquid injection pipe 4 is cut off from the inner tank side by the cryogenic valve 6, so cooling is not sufficient and heat enters from the outer tank. Tube 4 causes a temperature rise,
It becomes stable with a certain temperature gradient between the outer tank and the inner tank. Even if the tube 4 between the liquid injection inlet valve 8 and the low-temperature valve 6 is evacuated to reduce the heat intrusion caused by the heat transfer of helium gas, if the cut-off time becomes longer, the tube 4 will be reduced due to heat conduction. It will have a different temperature gradient.

Therefore, when additional liquid helium is injected after the inner tank is closed and kept cool, the temperature of the liquid injection pipe 4 has increased as described above, so the liquid helium that is sent will not reach the initial level of liquid helium injection. Then, the tube 4 is sent to the inner tank while being cooled. By the way, since liquid helium has a low latent heat of vaporization, it becomes a high-temperature helium gas and is directly sent into the inner tank until the pipe 4 is cooled at the initial stage of liquid injection. Since the helium gas sent into the inner tank has a high temperature, the liquid helium stored in the inner tank evaporates and is wasted. Also, at the beginning of injection, a large amount of high-temperature helium gas is sent into the inner tank, so the stored liquid helium rapidly evaporates and becomes gas helium.
There was a risk of causing an excessive pressure rise in the inner tank. Therefore, it was necessary to adjust the valve during additional injection to prevent internal pressure from increasing.

(3) Purpose of the invention To provide a cryogenic container structure in which the inner tank is closed off with a low-temperature valve, in which the refrigerant heated in the injection pipe and turned into evaporated gas during liquid injection is not directly sent into the inner tank. do.

(4) Summary of the invention The cryogenic container of the present invention has a structure in which a bypass system piping and a shutoff valve are installed in the low temperature section on the room temperature side of the low temperature valve, and when additional liquid is poured, the pipes on the room temperature side are precooled from the low temperature valve section. By injecting liquid into the inner tank, it is possible to prevent the evaporated gas of the refrigerant heated in the piping from being sent directly to the inner tank. Further, by making the low temperature valve on the liquid injection side a three-way valve structure and connecting the bypass system piping to the recovery system piping, the above effects can be expected without increasing the number of valves.

(5) Embodiments of the invention (Structure of embodiments) The cryogenic container of the present invention has a bypass pipe connecting a liquid injection pipe and a recovery pipe, and a shutoff valve for opening and closing the bypass pipe, in the low temperature part on the room temperature side of the low temperature valve. The configuration is such that it is provided. That is, as shown in FIG. 1, a bypass pipe 11 is provided from the room temperature side low temperature part of the liquid injection side low temperature valve 6 of the liquid injection pipe 4, and is connected to the room temperature side low temperature part of the recovery side low temperature valve 7 of the recovery pipe 5. , there is a shutoff valve 1 in the middle of the bypass pipe.
2. The shutoff valve 12 is a long-shaft valve similar to a low-temperature valve in order to reduce heat intrusion into the piping. In addition, when the inner tank is closed, by opening the shutoff valve 12, the liquid injection system and the recovery system are commonly connected by the bypass system, so the safety valve 10 for piping security is reduced to one. There is.

Furthermore, in order to avoid increasing the number of valves in the present invention, as shown in FIG. It is possible to create a configuration that does not require 12. 3-way valve 1 for low temperature valve on liquid injection side
3 has the structure shown in FIG. That is, the structure is such that the flow path can be branched by moving the valve body 13a up and down between the valve seat 13b of the low temperature valve to the inner tank and the insertion type bypass system valve seat 13c. In addition, the sealing material 14 closes off the temperature to the normal temperature side.

(Operation and effect of the embodiment) In the cryogenic container according to the present invention shown in FIG.
2 is opened, liquid helium is sent to the bypass pipe 11, and the liquid sending pipe 4 is cooled. By opening the liquid injection side low temperature valve 6, liquid helium is directly injected into the inner tank 1, and the liquid is stored in the inner tank. Additional liquid helium is injected without evaporating the liquid helium. In addition, to prevent the stored liquid helium from evaporating,
It also does not cause a sudden pressure increase in the inner tank due to evaporated gas.

(6) Other Embodiments Furthermore, as shown in FIG. 4, if the low-temperature valve on the liquid injection side is a three-way valve 13, the above-mentioned effect can be achieved without increasing the number of valves. In addition, as shown in Fig. 5, the operation of the three-way valve is such that when the position of the valve body 13a is indicated by a solid line, it indicates that liquid is being poured into the inner tank; be done. The bypass system is shut off by pressing the valve body 13a against the insertable bypass system valve seat 13c. When the position of the valve body 13a is indicated by a dotted line, it indicates a precooling state of the bypass system or a closed state of the inner tank, and precooling is performed in the system indicated by the dotted line arrow. The closure with inner tank 1 is valve body 1
3a against the valve seat 13b.

(7) Effects of the invention As mentioned above, by installing the bypass system in the low temperature section on the room temperature side of the low temperature valve and pre-cooling the piping before injecting liquid, additional liquid injection after the inner tank is closed is made possible. This can be done without evaporating the stored liquid helium. Furthermore, since the stored liquid helium does not cause rapid evaporation, a sudden pressure increase in the inner tank can be prevented. Furthermore, if the shutoff valve of the bypass system is opened when the inner tank is closed, the liquid injection system and the recovery system are commonly connected through the bypass system, so the number of safety valves for protecting the piping can be reduced to one.

Furthermore, by using a three-way valve as the low-temperature valve on the liquid injection side, the same effects as described above can be obtained without increasing the number of valves. Further, since the number of valves does not increase, there is no increase in the amount of heat entering from the valve portion, and a greater effect can be expected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a cryogenic container according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional cryogenic container, FIG. 3 is a block diagram of a cryogenic container according to another embodiment, and FIG. is a structural diagram of a three-way valve used in the present invention, and FIG. 5 is another structural diagram of the three-way valve. 1...Inner tank, 2...Outer tank, 3...Liquid helium, 4...Liquid injection system piping, 5...Recovery system piping,
6... Injection side low temperature valve, 7... Recovery side low temperature valve, 8...
... Liquid injection inlet valve, 9 ... Recovery outlet valve, 10 ... Safety valve, 11 ... Bypass system piping, 12 ... Shutoff valve, 13 ... 3-way valve, 13a ... Valve body, 13b ...
... Valve seat, 13c... Bypass system valve seat, 14... Seal material, 15... Coil spring, 16... Valve stem.

Claims (1)

[Claims] 1. Consisting of an inner tank storing cryogenic refrigerant liquid for cooling the superconducting electromagnet coil, and an outer tank at room temperature that adiabatically surrounds and stores this, the inner tank and the outer tank are penetrated. A liquid injection pipe for injecting the refrigerant liquid and a recovery pipe for recovering evaporated gas of the refrigerant liquid are provided, and each pipe is provided with a low temperature shut-off valve at an outer side of the inner tank and an inlet valve at an outer side of the outer tank. A bypass pipe is provided to directly connect the pipes on the room temperature side of the low temperature valve, and a shutoff valve is provided in the middle of the bypass pipe to pre-cool the liquid injection pipe outside the inner tank. Cryogenic container for superconducting electromagnetic coils. 2. The cryogenic container for a superconducting electromagnet coil according to claim 1, wherein a three-way valve is provided in place of the shutoff valve provided in the bypass pipe and the low temperature valve provided in the liquid injection pipe.