JP2000111185A - Cryogenic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply remove a hydrogen without vacuum contamination by incorporating a convenience to operate even in case of no supply of a power source in case of removing the hydrogen generated in a vacuum heat insulation tank. SOLUTION: The cryogenic apparatus 101 comprises a vacuum heat insulation tank 1 having a cold head 221 disposed therein to maintain a high vacuum state, and a hydrogen storage alloy 32 for storing hydrogen gas generated in the tank 1 in the high vacuum state. Since the alloy 32 to be operated without supply of a power source is used to remove the hydrogen gas, the gas can be removed even without supply of the power, and much convenience is provided. Since the gas can be removed even without using a vacuum pump or the like, there is no anxiety of vacuum contamination with oil or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cryogenic refrigerator such as a Stirling refrigerator and a GM refrigerator, and a cryogenic device such as a cryogenic container such as a cryostat. The present invention relates to a structure for maintaining a high degree of vacuum in a vacuum heat insulating tank of the apparatus.

[0002]

2. Description of the Related Art A cryogenic apparatus in which a cryogenic object such as a cryogenic refrigerator or a liquid nitrogen reservoir is disposed, and in which a high vacuum state is provided to maintain the cryogenic state, and a vacuum insulation tank is provided. In, a decrease in the degree of vacuum is observed due to various outgases generated from the members inside the vacuum heat insulating tank and the inner surface of the vacuum heat insulating tank. When the degree of vacuum is reduced to about 10 ⁻⁴ Pa, the effect of vacuum insulation is weakened, and a problem arises in that the amount of heat entering a cryogenic object inside the cryogenic device increases.

[0003] Usually, in the case of a cryogenic refrigerator, most of the outgas is adsorbed on the surface of the low temperature portion by the low temperature generated by itself, but the adsorption of hydrogen gas requires a cryogenic temperature of 20K or less. In the case where a low temperature of 20 K or less cannot be generated, or in the case of long-term operation, the hydrogen gas that has not been completely adsorbed often causes serious vacuum deterioration, which leads to a decrease in refrigeration capacity as described above.

[0004] Such vacuum deterioration due to hydrogen gas is unavoidable when a low temperature of 20 K or less is not inherently required, such as in a liquid nitrogen reservoir, and is a major factor in an increase in heat penetration. In these devices, in order to maintain a high vacuum, a turbo molecular pump is connected to perform vacuum evacuation as appropriate, or a vacuum chamber is equipped with a sputter ion pump, a titanium getter pump, a non-evaporable getter pump, etc., to perform vacuum evacuation. Need to do.

[0005]

However, these vacuum pumps are not only expensive, but also require a power supply for all pumps, and cannot be used without power supply. . further,
The turbo-molecular pump has a problem that in a high vacuum region, there is a concern that vacuum contamination due to reverse diffusion of oil used may occur. All other pumps have no concern about vacuum contamination, but have a problem that the pump itself becomes extremely hot and requires careful handling.

[0006] Therefore, the present invention has been made in view of the above circumstances, and in a cryogenic device, when removing hydrogen generated in a vacuum adiabatic tank, it is possible to operate without supplying power. An object of the present invention is to provide a convenient and easy removal of hydrogen without vacuum contamination.

[0007]

Means for Solving the Problems To solve the above technical problems, the invention of claim 1 comprises a vacuum heat insulating tank in which a cryogenic object is arranged and a high vacuum state is maintained,
A cryogenic device comprising: a hydrogen storage alloy that stores hydrogen generated inside the vacuum adiabatic tank under the high vacuum state.

According to the first aspect of the present invention, the cryogenic apparatus includes a vacuum insulation tank in which a cryogenic object is disposed and a high vacuum state is maintained, and a vacuum insulation tank in a high vacuum state. And a hydrogen storage alloy that stores generated hydrogen, so that hydrogen gas as an outgas generated on the members in the vacuum heat insulating tank and on the inner surface of the vacuum heat insulating tank is occluded by the hydrogen storage alloy, and efficiently. Removed.

As described above, according to the first aspect of the present invention, the hydrogen gas is occluded by the hydrogen occlusion alloy and is efficiently removed, so that the degree of vacuum in the vacuum adiabatic tank is reduced by the generation of the hydrogen gas. The high vacuum of the vacuum heat insulating tank can be maintained for a long time without reducing the effect of the vacuum heat insulating and increasing the heat penetration amount.

In addition, since hydrogen gas can be removed without using a vacuum pump or the like, there is no risk of vacuum contamination by oil or the like. In addition, the hydrogen storage alloy does not generate much heat when storing hydrogen, and is easy to handle.
It can easily remove hydrogen.

In order to solve the above technical problems, it is preferable that the hydrogen storage alloy is a hydrogen storage alloy capable of storing hydrogen at normal temperature.

According to the second aspect of the present invention, the hydrogen storage alloy is capable of storing hydrogen even at room temperature. In general, in a cryogenic device, in a vacuum insulated tank,
The cryogenic object itself is in a cryogenic state, but since the surrounding space is in a high vacuum, the cryogenic temperature of the cryogenic object is not transmitted to the surrounding space and is in a substantially normal temperature state. Therefore,
By using a hydrogen storage alloy that stores hydrogen even at room temperature as in the present invention, hydrogen gas can be removed without supply of power, and the invention is highly convenient.

In this case, more preferably, the hydrogen storage alloy is a Zr-V-Mn-based hydrogen storage alloy.

According to the third aspect of the present invention, a hydrogen storage alloy having a Zr-V-Mn composition is used as the hydrogen storage alloy. The hydrogen storage alloy having such a composition efficiently stores hydrogen even under a high vacuum and normal temperature condition. Therefore, it is possible to maintain a high vacuum state with an extremely high degree of vacuum for a longer time.

Further, the invention according to claim 4 is characterized in that the hydrogen storage alloy is sealed in a container, and the container is detachably attached to the vacuum heat insulating tank so that the container can be attached and detached while maintaining the airtight state of the vacuum heat insulating tank. A cryogenic device is characterized by being in communication.

According to the fourth aspect of the present invention, the hydrogen-absorbing alloy is sealed in the container, and the container in which the hydrogen-absorbing alloy is sealed is vacuum-insulated while maintaining the air-tight state of the vacuum heat-insulating tank. Since it is detachable from the tank and communicates with the vacuum insulation tank, when the hydrogen gas stored in the hydrogen storage alloy is saturated, removal of the container while maintaining the airtight state of the vacuum insulation tank, and A container in which a hydrogen storage alloy is newly enclosed can be attached. Therefore, when the hydrogen storage alloy is replaced, the airtight state of the vacuum heat insulating tank can be maintained, and the high vacuum of the vacuum heat insulating tank can be maintained for a longer time.

According to a fifth aspect of the present invention, the container communicates with the joint through a first passage via a first opening / closing valve, and the vacuum insulation tank is connected to a second joint via a second opening / closing valve. A first passage between the first on-off valve and the joint, or a middle of the second passage between the second on-off valve and the joint; It is preferable that the third passage is branched and a third on-off valve is interposed in the middle of the third passage.

According to the fifth aspect of the invention, the container in which the hydrogen storage alloy is sealed communicates with the joint through the first passage through the first opening / closing valve, and the vacuum heat insulating tank communicates through the second opening / closing valve. Second
A third passage is branched and communicates with the joint at the passage, between the first on-off valve and the joint, or between the second on-off valve and the joint, and in the middle of the third passage. Is provided with a third on-off valve, so when replacing the container in which the hydrogen storage alloy is sealed, both the first on-off valve and the second on-off valve are closed, and the container and the second Remove the entire passage. Then, when attaching a container in which a new hydrogen storage alloy is sealed, the container and the first passage are connected to the joint, the third on-off valve interposed in the third passage is opened, and the third passage is opened. Attach a vacuum pump or the like to the end of, and draw a vacuum. When a certain degree of vacuum is reached, the third on-off valve is closed to end the evacuation, and the first on-off valve interposed in the first passage is opened. Finally, the second on-off valve is opened. Thereby, the container and the vacuum insulation tank are communicated. At this time, since the inside of the passage is already evacuated, the degree of vacuum in the vacuum heat insulating tank does not decrease when the new hydrogen storage alloy-sealed container is connected to the vacuum heat insulating tank.

As described above, according to the fifth aspect of the present invention, when the container is detached from the vacuum heat insulating tank and the hydrogen storage alloy is replaced, the airtight state of the vacuum heat insulating tank is maintained with a simple configuration. It can be replaced and can maintain a high vacuum in the vacuum insulation tank for a long time.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a preferred first embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a cryogenic apparatus 101 according to this embodiment. As shown in the figure, the cryogenic device 101 mainly includes a vacuum heat insulating tank 1, a cryogenic refrigerator 2, and a hydrogen removing device 3.

The vacuum insulated tank 1 is composed of an aluminum chamber or the like, and the internal pressure is previously reduced to about 10 by a vacuum pump or the like.
It is in a high vacuum state of ⁻³ Pa or less.

The cryogenic refrigerator 2 is, for example, a Stirling refrigerator, and includes a drive unit 21 for driving the refrigerator and a refrigerator 22 for generating refrigeration. The refrigeration unit 22 is inserted into the internal space of the vacuum heat insulating tank 1, and has a configuration in which a cold head 221 attached to the tip thereof is disposed inside the vacuum heat insulating tank 1 as a cryogenic object.

The vacuum heat insulating tank 1 is provided with a hydrogen removing device 3. This hydrogen removing device 3 is made of Zr-V-Mn.
It has a container 32 in which a powdery hydrogen storage alloy 31 having a system composition is enclosed. One end surface 32 a of the container 32 is connected to and communicates with one end of the first passage 33. The first passage 33 is provided with a first on-off valve 34 in the middle thereof, and the other end is connected to one surface side of the joint 35. Joint 3
One end of the second passage 36 is connected to the other surface of the fifth surface 5.
The second passage 36 is provided with a second on-off valve 37 in the middle thereof.
The other end is connected to the vacuum insulation tank 2 and communicates with the internal space of the vacuum insulation tank 2. In the middle of the second passage 36 between the second on-off valve 37 and the joint 35, a third passage 3 is provided.
8 are branched and connected. A third on-off valve 39 is interposed in the third passage 38.

In the cryogenic device 101 having the above-described structure, the inside of the vacuum heat insulating tank 1 is in a high vacuum state,
The cryogenic refrigerator 2 operates to generate a cryogenic temperature in the cold head 221. By bringing the non-cooled body into contact with the cold head 221, the non-cooled body is cooled, and the frozen state is maintained.

In the hydrogen removing device 3, the first on-off valve 34 and the second on-off valve are open. Therefore, the vacuum heat insulating tank 1 and the container 32 communicate with each other through the first passage 33 and the second passage 36, and the space in the container 32 is also in a high vacuum state. However, the cold head 2 in the vacuum insulation tank 1
In addition to being located at a considerable distance from 21 and being in a high vacuum state, the cryogenic temperature of the cold head 221 is not transmitted to the container 32, and the container 32 is kept at room temperature. Further, since the vacuum heat insulating tank 1 and the container 32 are in communication with each other, the hydrogen storage alloy sealed in the container 32 is in a state capable of storing hydrogen gas generated in the vacuum heat insulating tank 1. I have. The third on-off valve 39 is closed,
Inner space of vacuum insulation tank 1 and second passage 3 communicating therewith
6. The inner space of the first passage 33 and the container 32 is a closed space that is isolated from the outer space.

During operation of the cryogenic refrigerator 2, various gases are generated as outgas in the vacuum adiabatic tank 1, but most of the gases except for the hydrogen gas are transferred to the cold head 221 and the cold trap near the cold head 221. It is adsorbed.
However, hydrogen gas is hardly trapped in these low-temperature portions and floats in the vacuum heat insulating tank 1. In this case, the inside of the container 32 communicates with the vacuum heat-insulating tank 1 via the second passage 36 and the first passage 33, and since the hydrogen storage alloy 31 is sealed in the inside of the container 32, it floats. Hydrogen gas is stored in the hydrogen storage alloy 31. Thus, the hydrogen gas is removed.

The amount of hydrogen gas absorbed by the hydrogen storage alloy 31 is finite, and when the absorbed hydrogen gas approaches the saturation amount,
The storage capacity is reduced. For this reason, the degree of vacuum in the vacuum heat insulating tank 1 cannot be maintained unless the container in which the hydrogen storage alloy is regenerated or the container in which the new hydrogen storage alloy is stored is replaced. The replacement procedure in this case will be described below.

In order to replace the container 32 containing the hydrogen storage alloy 31, first, both the second on-off valve 37 and the first on-off valve 34 are closed to cut off the communication between the vacuum insulation tank 1 and the container 32. Next, the connection between the one end surface of the joint 35 and the other end of the first passage 33 is released, and the container 32 is removed together with the first passage 33 and the first on-off valve 34. Next, in order to mount the container 32 in which the new hydrogen storage alloy 31 is sealed, the other end of the first passage 33 is connected to one end surface of the joint 35, and the removed portion is mounted again. Next, the third opening / closing valve 39 interposed in the third passage 38 is opened, and a vacuum pump or the like is attached to the end of the third passage 38 to evacuate. Next, the first
The first on-off valve 34 interposed in the passage 33 is opened.
At this time, since the second on-off valve 37 is closed, the vacuum heat insulating tank 1 and the third passage 38 are not in communication with each other, and the portion to be evacuated is the third passage 38 and the second passage 36. Only the portion between the two on-off valve 37 and the joint 35, the first passage 33, and the inner space of the container 32 are provided. When a certain degree of vacuum is reached by evacuation, the third on-off valve 39 is closed to end the evacuation, and finally the second on-off valve 37 is opened. Thereby, the container 32 and the vacuum heat insulating tank 1 are communicated. At this time, since the inner space of the second passage 36, the first passage 33, and the inner space of the container 32 have already been evacuated, when the container 32 in which the new hydrogen storage alloy 31 is sealed and the vacuum heat insulating tank 1 are connected. In addition, the degree of vacuum in the vacuum insulation tank 1 does not decrease.

As described above, when the container is detached from the vacuum insulation tank and the hydrogen storage alloy is replaced, the container can be replaced with a simple configuration while maintaining the airtight state of the vacuum insulation tank. High vacuum can be maintained.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 2. The same parts as those in the first embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted. Description is omitted.

FIG. 2 shows the cryogenic device 102 in this embodiment. As shown in the figure, the cryogenic device 102 mainly includes a vacuum heat insulating tank 1, a liquid nitrogen storage tank 4, and a hydrogen removing device 3.

The liquid nitrogen storage tank 4 is housed in the vacuum heat insulating tank 1. The liquid nitrogen storage tank 4 is filled with liquid nitrogen 41 as a cryogenic object and disposed in the vacuum heat insulating tank 1. The liquid nitrogen 41 is used for cooling a shield plate as a non-cooling body, for example.

The other detailed configurations of the adiabatic vacuum tank 1 and the hydrogen removing device 3 are the same as those of the first embodiment, and therefore, detailed description thereof will be omitted.

In the cryogenic device 102 having the above-described structure, the inside of the vacuum heat insulating tank 1 is in a high vacuum state and is insulated by vacuum from the outside. Evaporation is kept to a minimum.

In the hydrogen removing device 3, the first on-off valve 34 and the second on-off valve 37 are open. Therefore, the vacuum heat insulating tank 1 and the container 32 are connected by the first passage 33 and the second passage 36.
The space inside the container 32 is also in a high vacuum and normal temperature state. In addition, the vacuum insulation tank 1 and the container 32
Are in communication with each other, so that the hydrogen storage alloy sealed in the container 32 can store hydrogen gas generated in the vacuum heat insulating tank 1. Further, the third opening / closing valve 39 is closed, and the inner space of the vacuum insulated tank 1 and the inner space of the second passage 36, the first passage 33 and the container 32 communicating therewith are the closed space which is cut off from the outer space. Have been.

In the above description, various gases are generated as outgas in the vacuum heat insulating tank 1. Most of the gases except for the hydrogen gas are cold trapped and adsorbed on the liquid nitrogen 41 and a low-temperature portion near the liquid nitrogen 41. However, hydrogen gas is hardly trapped in these low-temperature parts, and the
Floating inside. In this case, the second heat path 3
6. The inside of the container 32 communicates via the first passage 33,
Further, since the hydrogen storage alloy 31 is sealed inside the container 32, the floating hydrogen gas is adsorbed by the hydrogen storage alloy 31. Thus, the hydrogen gas is removed.

The procedure for replacing the hydrogen storage alloy in the present embodiment is the same as the procedure described in the first embodiment, and a description thereof will be omitted.

FIG. 3 is a graph showing the relationship between the hydrogen storage amount of the hydrogen storage alloy at room temperature and the equilibrium pressure using the composition of the hydrogen storage alloy as a parameter. In addition, the graph A is Zr−
Graph B of Mn-Al system, graph C of Zr-Ni system
Shows the relationship between the hydrogen storage amount and the equilibrium pressure when a hydrogen storage alloy having a Zr-V-Mn-based composition is used.
In this graph, for example, in a high vacuum state of 10 ⁻⁴ torr, Zr—Mn—A having the characteristics shown in graph A
The l-type hydrogen storage alloy hardly stores hydrogen gas, and the Zr-Ni-type hydrogen storage alloy having the characteristics shown in Graph B stores only about 20 cc of hydrogen gas per gram. On the other hand, Zr-V having the characteristics shown in graph C
It can be seen that -Mn-based hydrogen storage alloys absorb 200 cc or more of hydrogen gas per gram. Therefore, when using the hydrogen storage alloy in the cryogenic device shown in the first embodiment and the second embodiment, Z
By using an r-V-Mn-based hydrogen storage alloy,
A larger amount of hydrogen gas can be stored, and a high vacuum in the vacuum insulation tank 1 can be reliably maintained.

As described above, according to the first and second embodiments, the cryogenic device 101 or 102 is used.
Is a vacuum insulated tank 1 in which a cold head 221 or liquid nitrogen 41 as a cryogenic object is disposed and a high vacuum state is maintained, and a hydrogen gas generated inside the vacuum insulated tank 1 under a high vacuum state. Since it has the hydrogen storage alloy 31 to be stored, the hydrogen gas as an outgas generated in the members in the vacuum heat insulating tank 1 and the inner surface of the vacuum heat insulating tank 1 is occluded by the hydrogen storage alloy, and is efficiently removed. Is done. For this reason, the degree of vacuum in the vacuum insulation tank is reduced by the generation of hydrogen gas, the effect of vacuum insulation is reduced, and the high vacuum of the vacuum insulation tank is maintained for a long time without increasing the heat penetration amount. Can be done.

Since hydrogen gas can be removed without using a vacuum pump or the like, there is no risk of vacuum contamination by oil or the like. In addition, the hydrogen storage alloy does not generate much heat when storing hydrogen, and is easy to handle.
It can easily remove hydrogen.

Since the hydrogen storage alloy is a hydrogen storage alloy capable of storing hydrogen at room temperature, it does not require a power supply for raising the temperature as in a getter pump and requires a high vacuum and room temperature condition. Thus, hydrogen can be absorbed more efficiently, which is convenient.

Further, the hydrogen storage alloy is used at room temperature and for 1 hour.
Because it uses 0 ^-4 torr Zr-V-Mn based hydrogen absorbing alloy capable of absorbing a 1g per 200cc stuff hydrogen gas at a high degree of vacuum of, maintaining a very high vacuum high vacuum more for a long time It is possible.

The container 32 is connected to the joint 35 via a first passage 33 via a first opening / closing valve 34, and the vacuum insulated tank 1 is joined via a second passage 36 via a second opening / closing valve 37. 35, a third passage 38 is branched in the middle of the second passage 36 between the second on-off valve 37 and the joint joint 35, and a third passage 38 is provided in the middle of the third passage 38. Since the on-off valve 39 is interposed, the second on-off valve 37
Is closed, and then the container 32 is separated from the vacuum heat insulating tank 1 at the joint joint 35, whereby the hydrogen storage alloy 31 can be replaced while the airtight state of the vacuum heat insulating tank 1 is maintained. Also, with a simple configuration of each passage and each on-off valve, the vacuum insulation tank can be replaced while maintaining the airtight state, and the high vacuum of the vacuum insulation tank can be maintained for a long time.

[0045]

According to the present invention, when removing hydrogen generated in a vacuum adiabatic tank, hydrogen is easily operated without power supply, and hydrogen is easily removed without vacuum contamination. Can be a cryogenic device capable of eliminating the cryogenic temperature.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cryogenic device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a cryogenic device according to a second embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the hydrogen storage amounts of various hydrogen storage alloys and the equilibrium pressure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum insulation tank 2 ... Cryogenic refrigerator 21 ... Driving part 22 ... Refrigeration generation part 221 ... Cold head (cryogenic object) 3 ... Hydrogen removal device 31 ...・ Hydrogen storage alloy, 32 ・ ・ ・ Container, 33 ・
..First passages, 34 ... first on-off valves, 35 ...
Joining joint, 36 ... second passage, 37 ... second on-off valve, 38 ... third passage, 39 ... third on-off valve 4 ... liquid nitrogen storage tank 41 ... liquid nitrogen ( Cryogenic object) 101, 102 ... Cryogenic device

Claims (5)

[Claims] A vacuum insulation tank in which a cryogenic object is disposed and a high vacuum state is maintained; and a hydrogen storage alloy for storing hydrogen gas generated inside the vacuum insulation tank under the high vacuum state. A cryogenic device comprising: 2. The cryogenic device according to claim 1, wherein the hydrogen storage alloy is a hydrogen storage alloy capable of storing hydrogen gas at normal temperature. 3. The cryogenic device according to claim 2, wherein the hydrogen storage alloy is a Zr—V—Mn-based hydrogen storage alloy. 4. The method according to claim 1, wherein
The cryogenic device, wherein the hydrogen storage alloy is sealed in a container, and the container is connected to the vacuum heat insulating tank so as to be detachable while maintaining the airtight state of the vacuum heat insulating tank. . 5. The container according to claim 4, wherein the container communicates with the joint through a first passage through a first opening / closing valve, and the vacuum insulation tank is connected to the second joint via a second opening / closing valve.
A first passage between the first on-off valve and the joint, or a middle of the second passage between the second on-off valve and the joint; Third
A cryogenic device, wherein a passage is branched and a third on-off valve is interposed in the middle of the third passage.