JP5442506B2 - Cooling device and recondensing device - Google Patents

Description

  The present invention relates to a cooling device and a recondensing device, and more particularly to a cooling device and a recondensing device in which a vacuum adsorber is provided in a vacuum vessel.

  Conventionally, for example, liquid helium is used as a cooling refrigerant for an apparatus having a liquid helium temperature level such as an SQUID apparatus (superconducting quantum interference device) or an SCM apparatus (superconducting magnet apparatus). FIG. 3 shows such an apparatus 100.

  A portion of liquid helium evaporates during the cooling process and must be recondensed. For this reason, as shown in the figure, by using a recondensing device 104 having a structure in which a cooling device 103 is connected to a refrigerant tank 102 in which a refrigerant 101 such as liquid helium is stored, the evaporated refrigerant is cooled by the cooling device 103. It is configured to recondense and return to the refrigerant tank 102.

  FIG. 4 is an enlarged view of the cooling device 103 provided in the recondensing device. The cooling device 103 shown in the figure has a configuration in which a Joule-Thomson circuit 106 (hereinafter referred to as a JT circuit) provided with a Joule-Thomson valve 107 is added to a Gifford-McMahon cycle refrigerator 105 (hereinafter referred to as a GM refrigerator). Has been.

  Since the GM refrigerator 105 and the JT circuit 106 generate extremely low temperatures, it is necessary to block the intrusion of heat from the outside. For this reason, inserting the cooling part of GM refrigerator 105 and the JT circuit 106 in the vacuum vessel 108 is performed. The inside of the vacuum vessel 108 is sucked by a vacuum pump to have a predetermined degree of vacuum.

  In order to prevent heat penetration from the outside to the GM refrigerator 105 and the JT circuit 106, a high degree of vacuum is required, so a vacuum adsorber 110 is disposed in the vacuum vessel 108 (see Patent Document 1). ). The vacuum adsorber 110 is an activated carbon panel, for example, and is attached to the cooling stage 105 a of the GM refrigerator 105.

  The cooling stage 105a is the second cooling stage of the two-stage GM refrigerator 105, and is a part that is at an extremely low temperature of about 8K to 15K. For this reason, gas molecules (hydrogen molecules, nitrogen molecules, etc.) remaining in the vacuum vessel 108 even after the suction processing by the vacuum pump are adsorbed by the vacuum adsorber 110 which is set to a very low temperature. Thereby, the inside of the vacuum container 108 can be made into a high vacuum state, and the penetration | invasion of the heat from the outside can be suppressed.

JP 11-257770 A

  However, in the conventional cooling device 103 and the recondensing device 104 using the same, since the vacuum adsorber 110 is provided in the GM refrigerator 105, assuming that the GM refrigerator 105 is stopped due to a power failure or the like, As a result, the temperature of the vacuum adsorber 110 rises. As a result, the gas molecules adsorbed in the vacuum vessel 108 are released again from the vacuum adsorber 110 into the vacuum vessel 108, and the degree of vacuum in the vacuum vessel 108 decreases. For this reason, when the GM refrigerator 105 is restarted after being stopped, the vacuum adsorber 110 needs to be evacuated again, and the efficiency of the recondensing device 104 and the device 100 using the same is reduced. was there.

  This invention is made | formed in view of said point, and even if a refrigerator stops, it aims at providing the cooling device and recondensing device which can maintain the vacuum degree in a vacuum vessel in a high state.

From the first point of view, the above problem is
A cooling device that is attached to a recondensing device that performs a recondensing process when the refrigerant stored in the refrigerant tank is vaporized, and that cools the vaporized refrigerant,
A refrigerator that performs a cooling process;
A vacuum container having an insertion tube inserted therein in a state in which heat can be exchanged with the refrigerant tank, while storing a part of the refrigerator;
This can be solved by a cooling device in which a vacuum adsorber for adsorbing gas molecules in the vacuum vessel is provided at least at a position where heat exchange with the refrigerant tank in the insertion tube is possible.

In addition, the above problem is from the second point of view.
A refrigerant tank containing a refrigerant;
A recondensing device having a cooling device for recondensing by cooling the vaporized refrigerant gas when the refrigerant stored in the refrigerant tank is vaporized,
The cooling device is
A refrigerator that performs a cooling process;
A vacuum container having an insertion tube inserted therein in a state in which heat can be exchanged with the refrigerant tank, while storing a part of the refrigerator;
This can be solved by a recondensing device characterized by having a vacuum adsorber that adsorbs gas molecules in the vacuum vessel at least at a position where heat exchange with the refrigerant tank in the insertion tube is possible.

  According to the disclosed cooling device and recondensing device, the refrigerator was stopped by providing a vacuum adsorber that adsorbs gas molecules in the vacuum vessel at a position where heat exchange with the refrigerant tank in the insertion tube was possible. However, since the vacuum adsorber is cooled by the refrigerant gas in the refrigerant tank and maintains the adsorption of the gas molecules, the degree of vacuum in the vacuum vessel can be maintained.

FIG. 1 is a configuration diagram for explaining a cooling device and a recondensing device according to an embodiment of the present invention. FIG. 2 is a diagram for explaining a configuration of a vacuum adsorber provided in a cooling device and a recondensing device according to an embodiment of the present invention. FIG. 3 is a configuration diagram for explaining an example of a conventional cooling device and recondensing device. FIG. 4 is a configuration diagram for explaining a conventional cooling device.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing a recondensing device 1 and a cooling device 3 according to an embodiment of the present invention. The recondensing device 1 provided with the cooling device 3 is applied to a device that performs processing at a liquid helium temperature level, such as a SQUID device or an SCM device.

  The recondensing device 1 generally includes a refrigerant tank 2, a cooling device 3, vacuum adsorbers 10, 11 and the like. The refrigerant tank 2 contains a refrigerant 4 that cools an object to be cooled (one to be cooled in the SQUID apparatus or the SCM apparatus). In the present embodiment, an example in which liquid helium is used as the refrigerant 4 is shown. However, the type of the refrigerant 4 is not limited to liquid helium, and other refrigerants such as liquid nitrogen can be used.

  Moreover, since the refrigerant tank 2 is configured to store the liquefied refrigerant 4 therein, it is necessary to prevent heat from entering from the outside in terms of preventing vaporization of the refrigerant 4. For this reason, the refrigerant tank 2 is provided in the inside of the vacuum chamber 6 for refrigerant | coolant which can be made into a vacuum state inside.

  In the present embodiment, the cooling device 3 is configured by adding a JT circuit 30 to a Gifford McMahon refrigerator 20 (hereinafter referred to as a GM refrigerator). The GM refrigerators 20 and 30 both use helium gas as the refrigerant gas. In addition, although the example which applied GM refrigerator 20 as a refrigerator is shown in this embodiment, it replaces with GM refrigerator 20, and other cool storage type refrigerators, such as a pulse tube refrigerator and a Stirling refrigerator, are applied. It is also possible.

  The GM refrigerator 20 applied in the present embodiment has a first-stage cooling stage 21 on the low temperature side (lower part) of the first-stage cylinder 23, and a two-stage cylinder 24 disposed below the first-stage cooling stage 21. This is a so-called two-stage GM refrigerator having a two-stage cooling stage 22 on the low temperature side (lower part). When the GM refrigerator 20 is activated, the displacer with the cold storage material reciprocally moves in the cylinders 23 and 24 to adiabatically expand the refrigerant gas, and the first and second cooling stages 21 and 22 generate cold. To do. As a result, the temperature of the first stage cooling stage 21 is 45 to 90K, for example, and the temperature of the second stage cooling stage 22 can be cooled to 4K or less, for example.

  However, it is difficult to generate a large refrigeration capacity with a single GM refrigerator. For this reason, when a large refrigeration capacity is required at 4K, the GM refrigerator 20 alone cannot cope with it, so the Joule-Thomson circuit 30 (hereinafter referred to as a JT circuit) is added to the GM refrigerator 20 to constitute the cooling device 3. (See JP 10-73333 A and JP 11-108476 A).

  The JT circuit 30 includes three coolers 31, 32, 33, three heat exchangers 34, 35, 36, a JT valve 38, and the like. Moreover, since the cooling device 3 produces | generates the cryogenic temperature of 4K vicinity as mentioned above, it is necessary to suppress the heat | fever penetration | invasion from the outside. Therefore, the cooling stages 21 and 22 constituting the GM refrigerator 20, the cylinders 23 and 24, the coolers 31, 32 and 33 constituting the JT circuit 30, the heat exchangers 34, 35 and 36, and the JT valve 38. Is housed inside the vacuum vessel 12.

  The vacuum vessel 12 is provided with a connection valve (not shown) connected to an evacuation device. The connection valve is connected to the evacuation device and evacuated to be sealed to a predetermined degree of vacuum. . However, in order to maintain the vacuum heat insulating effect, it cannot be said that evacuation by the evacuation device alone is sufficient. Further, there is a possibility that emitted gas is released from the surface of each material constituting the GM refrigerator 20 and the JT circuit 30, and in this case, the degree of vacuum is further reduced. Note that the gas that has not been removed by suction as described above, the gas generated from each material, and the like are collectively referred to as residual gas. The main components of this residual gas are nitrogen gas, oxygen gas, carbon dioxide gas and the like.

  If residual gas exists in the vacuum vessel 12, the degree of vacuum in the vacuum vessel 12 is lowered, and the vacuum heat insulation effect is reduced, and there is a possibility that a favorable cooling process cannot be performed. Therefore, in the present embodiment, the first and second vacuum adsorbers 10 and 11 are provided inside the vacuum container 12 to increase the degree of vacuum in the vacuum container 12. The details of the first and second vacuum suction devices 10 and 11 will be described later for convenience of explanation.

  Next, operations of the recondensing device 1 and the cooling device 3 will be described.

  The high-pressure (1 to 2 MP) helium gas exiting from the compressor 40 of the JT circuit 30 first enters the first heat exchanger 34 and is cooled to about 90K through heat exchange with the returning low-temperature helium gas. Next, the helium gas flows into the first stage cooler 31 provided in the first stage cooling stage 21 of the GM refrigerator 20, and is cooled to about 75K here. The first stage cooler 31 compensates for a loss mainly generated in the first heat exchanger 34.

  Next, the helium gas enters the second heat exchanger 35 and is cooled to about 15K by exchanging heat with the returning low temperature helium gas. The two-stage cooler 32 provided in the two-stage cooling stage 22 of the GM refrigerator 20 is cooled to about 10K. Next, the helium gas enters the third heat exchanger 36 and is cooled to about 6K by exchanging heat with the returning low-temperature helium gas.

  The helium gas has a reversal temperature at about 30 K, and there is a region where the temperature decreases due to expansion below this temperature. Therefore, when the high-pressure helium gas cooled to about 6K is expanded to atmospheric pressure (0.1 MPa) or less by adiabatic free expansion, a part of the gas becomes liquid. The amount of liquefaction depends on the temperature and pressure before expansion and the pressure after expansion.

  Helium gas is expanded through a JT valve 38 which is an expansion valve. Since this expansion is adiabatic free expansion, the expansion valve is merely a throttle valve. The expanded helium cools the condenser 14 by the load cooler 33.

  An insertion tube 13 having an elongated cylindrical shape is integrally formed at the lower portion of the vacuum vessel 12. A condenser 14 is provided at the distal end of the insertion tube 13. The vacuum vessel 12 and the insertion tube 13 are made of stainless steel. Further, the load cooling unit 33 of the JT circuit 30 is disposed in the condenser 14, and thus the condenser 14 is cooled by helium flowing through the condenser 14.

  Further, the insertion tube 13 and the condenser 14 disposed at the tip thereof are configured to be inserted into the refrigerant tank 2. Therefore, when the refrigerant 4 (liquid helium) evaporates in the refrigerant tank 2 to become the refrigerant gas 5 (helium gas, indicated by a wavy arrow in the figure), the refrigerant gas 5 is at a very low temperature (for example, 4K). The condensed condenser 14 is re-condensed by touching and falls again toward the lower part of the refrigerant tank 2. Thereby, the leakage of the refrigerant gas 5 from the refrigerant tank 2 can be prevented and the number of replenishments of the refrigerant 4 can be reduced.

  On the other hand, the liquid helium flowing in from the JT valve 38 becomes helium gas again by absorbing heat in the condenser 14. The helium gas returns to room temperature by flowing through the third heat exchanger 36, the second heat exchanger 35, and the first heat exchanger 34 in order from the load cooling unit 33, and is compressed by the compressor 40 again.

  Here, the first vacuum suction device 10 and the second vacuum suction device 11 will be described. In the present embodiment, the first and second vacuum adsorbers 10 and 11 both use activated carbon. Specifically, the first vacuum adsorber 10 has a configuration in which activated carbon is adhered to the inner wall of the insertion tube 13 having a cylindrical shape as shown in FIG. The second vacuum adsorber 11 is made of an activated carbon panel, and is disposed in the two-stage cooling unit 32 of the GM refrigerator 20.

  The first vacuum adsorber 10 is cooled mainly by the refrigerant gas 5 generated by the evaporation of the refrigerant 4 in the refrigerant tank 2. The second vacuum adsorber 11 is cooled mainly by the two-stage cooling stage 22 of the GM refrigerator 20.

  Thus, the 1st and 2nd vacuum adsorption devices 10 and 11 adsorb | suck the residual gas molecule which exists in the vacuum vessel 12 by being cooled to cryogenic temperature. Thereby, the vacuum degree inside the vacuum vessel 12 can be increased, and the vacuum insulation by the vacuum vessel 12 can be performed reliably. Thereby, heat can be prevented from entering the vacuum vessel 12 from the outside of the cooling device 3, the cooling efficiency of the cooling device 3 is increased, and the recondensing process of the refrigerant gas 5 can be performed satisfactorily.

  Here, in the recondensing device 1 and the cooling device 3 according to the present embodiment, it is assumed that the GM refrigerator 20 has stopped due to, for example, a power failure.

  When the GM refrigerator 20 stops, the cooling process by the GM refrigerator 20 and the JT circuit 30 stops. For this reason, the temperature in the vacuum vessel 12 rises, and the residual gas molecules adsorbed in the second vacuum adsorber 11 are released again into the vacuum vessel 12, so that the degree of vacuum in the vacuum vessel 12 decreases. There is concern.

  However, in the present embodiment, the first vacuum suction device 10 is arranged in the insertion tube 13. Further, the first vacuum adsorber 10 is disposed at the distal end portion of the insertion tube 13, and the distal end portion of the insertion tube 13 is inserted into the refrigerant tank 2. That is, the first vacuum adsorber 10 is disposed at a position where heat exchange with the refrigerant tank 2 (specifically, the refrigerant gas 5) in the insertion tube 13 is possible.

  Therefore, the first vacuum adsorber 10 is cooled by the refrigerant gas 5 in which the refrigerant 4 in the refrigerant tank 2 is evaporated. The cooling of the insertion tube 13 by the refrigerant gas 5 is performed regardless of whether the GM refrigerator 20 and the JT circuit 30 are stopped. For this reason, even if the residual gas molecules adsorbed by the second vacuum adsorber 11 are released from the second vacuum adsorber 11, the residual gas molecules are adsorbed by the first vacuum adsorber 10, so that the vacuum The degree of vacuum in the container 12 is not greatly reduced.

  As a result, when the GM refrigerator 20 and the JT circuit 30 are started again after a power failure, the vacuum vessel 12 maintains a high degree of vacuum and a state in which intrusion of heat from the outside is suppressed. The recondensation process can be started. Therefore, since the influence on devices such as the SQUID device and the SCM device provided with the recondensing device 1 can be almost eliminated, the reliability of the recondensing device 1 can be improved.

  In this embodiment, a configuration in which two vacuum suction devices are provided in the vacuum container 12 (a configuration in which the first vacuum suction device 10 and the second vacuum suction device 11 are provided) is adopted. However, the second vacuum suction device 11 is not necessarily provided, and only the first vacuum suction device 10 can realize the effect of the present invention.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments described above, and various modifications are possible within the scope of the gist of the present invention described in the claims. It can be modified and changed.

DESCRIPTION OF SYMBOLS 1 Recondensing device 2 Refrigerant tank 3 Cooling device 4 Refrigerant 5 Refrigerant gas 6 Refrigerant vacuum chamber 10 First vacuum adsorber 11 Second vacuum adsorber 12 Vacuum vessel 13 Insertion tube 14 Condenser 18 GM compressor 20 GM refrigerator 21 1st stage cooling stage 22 2nd stage cooling stage 23 1st stage cylinder 24 2nd stage cylinder 30 JT circuit 31 1st stage cooling part 32 2nd stage cooling part 33 Load cooling part 34 1st heat exchanger 35 2nd heat exchange 36 Third heat exchanger 38 JT valve

Claims (7)

A cooling device that is attached to a recondensing device that performs a recondensing process when the refrigerant stored in the refrigerant tank is vaporized, and that cools the vaporized refrigerant,
A refrigerator that performs a cooling process;
A vacuum container having an insertion tube inserted therein in a state in which heat can be exchanged with the refrigerant tank, while storing a part of the refrigerator;
A cooling device characterized in that a vacuum adsorber for adsorbing gas molecules in the vacuum vessel is provided at least at a position where heat exchange with the refrigerant tank in the insertion tube is possible.   The cooling device according to claim 1, wherein the vacuum suction device is disposed at a distal end portion of the insertion tube.   The cooling apparatus according to claim 1 or 2, wherein the refrigerator is a regenerative refrigerator.   The cooling apparatus according to claim 1 or 2, wherein the refrigerator has a configuration in which a regenerative refrigerator and a Joule-Thomson circuit are added.   The cooling device according to claim 1, wherein the refrigerant is helium.   The cooling apparatus according to any one of claims 1 to 5, wherein the vacuum adsorber is made of activated carbon disposed on an inner wall of the insertion tube. A refrigerant tank containing a refrigerant;
A recondensing device having a cooling device for recondensing by cooling the vaporized refrigerant gas when the refrigerant stored in the refrigerant tank is vaporized,
The cooling device is
A refrigerator that performs a cooling process;
A vacuum container having an insertion tube inserted therein in a state in which heat can be exchanged with the refrigerant tank, while storing a part of the refrigerator;
A recondensing apparatus comprising a vacuum adsorber that adsorbs gas molecules in the vacuum vessel at least at a position where heat exchange with the refrigerant tank in the insertion tube is possible.

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