JPS63302280A - Method of liquefying helium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for liquefying helium gas. The present invention can obtain liquid helium used in ultrahigh-speed computers, infrared detectors, nuclear magnetic resonance devices, etc.

(Prior Art) As a conventional method for obtaining liquid helium, a regenerator refrigeration cycle with a J-T loop is known.

This method was developed by Stirling and Gifford-Memah.
A refrigerating temperature of about 15 to 20 K is obtained using a regenerator refrigeration cycle such as a refrigerating system such as a refrigerating system such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine, and a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerating machine such as a refrigerant. Helium gas cooled to 15-2 OK is adiabatically expanded through a Joule-Thomson valve, and a portion of the gas is liquefied to obtain liquid helium.

FIG. 4 shows a typical refrigerator using a regenerator refrigeration cycle with a J-T loop. This refrigerator is the first regenerator type.
Cooling system [100 and J-T loop type second cooling system! 200
It consists of. The first regenerator cooling device 100 includes a compressor 101 and an expander 104 having a first expansion chamber 102 and a second expansion chamber 103. J-T type second cold m device 20
0 is a compressor 201, a first heat exchanger 202, a second
Heat exchanger M device 203, third heat exchanger 204 and first cooling section 20
5. Consists of a second cooling unit 206, a J-'r valve 207, and a liquid helium tank 208. The helium gas loop starts from the compressor 201 to the first heat exchanger 202, to the first cooling section 205, to the second heat exchanger 203, to the second cooling section 20.
6. An outgoing path that passes through the third heat exchanger 204 and the J-T valve 207 and reaches the liquid helium tank 208, and further from the liquid helium tank 208 to the third heat exchanger 204 and the second heat exchanger yA.
The compressor 2 passes through the heat exchanger 203 and the first heat exchanger 202.
and a return trip back to 01. In this refrigerator, the helium gas in the J-T type second cooling device C200 is sufficiently precooled through the first cooling section 205 and second cooling section 206 of the regenerator type first cooling device 100, and is then cooled in the J-T pulp 207. Isenthalpic expansion causes a part of the gas to liquefy, forming a liquid helium tank 20.
Stored within 8. Most of the helium gas that has not been liquefied takes a return route from the liquid helium tank 208 to the third heat exchanger 20.
4. Heat is exchanged with the second heat exchanger 203 and the first heat exchanger 202 one after another, and then returns to the compressor 201.

(Problems to be solved by the invention) A refrigerator using this regenerator refrigeration cycle with a J-T loop requires a large amount of helium gas to be circulated along the J-T loop, so the refrigerator itself is large. There is a problem with becoming.

In addition, when expanding with a J-T valve, helium gas is 1~
There was a limit to the cooling part of the working medium that utilized Joule-Thomson expansion.

The present invention was made in view of the above-mentioned circumstances, and provides a helium liquefaction method that allows liquid helium to be obtained more easily.

[Means for Solving the Problems] The helium liquefaction method of the present invention comprises: a compression chamber in which helium as a working medium is compressed; a heat radiation part that releases the heat of compression of the compressed helium; and communication with the heat radiation part. A heat exchanger installed between the regenerator and the expansion chamber of the refrigerator has a regenerator for storing helium, and an expansion chamber in which the helium expands after passing through the regenerator. It is characterized by cooling and liquefying helium gas.

The present invention is based on the discovery that in a regenerator refrigerator using helium gas as a working medium, by cooling the heat dissipation section with refrigeration of about 20%, it is possible to achieve refrigeration at a humidity lower than the liquefaction humidity of helium.

The refrigerator used in the helium liquid conversion method of the present invention includes a compressor for compressing helium as a working medium, a heat radiator that releases the heat of compression of the compressed helium, and a cold storage that communicates with the heat radiator. and an expansion chamber in which the helium that has passed through the regenerator expands.

As such refrigerators, refrigerators operating on a regenerative refrigeration cycle, such as Sterling, Gifford-McMuffon, Truvay, and Builiuma, can be used. The heat dissipation section of this refrigerator has at least 4011f of refrigeration, more preferably 2
It is necessary to cool down with refrigeration lower than 0. This cold W machine needs to be provided with a heat exchanger between the cold storage section and the expansion chamber to cool helium gas, which is different from helium as the production medium.

The helium gas to be liquefied is also pre-cooled to a temperature of 40° C. or less, more preferably 20° C. or less. A known refrigerator can be used for this precooling. This pre-cooled helium gas is sent to the heat exchanger of the refrigerator where it is cooled to below the liquefaction temperature of helium to obtain liquid helium.

The pressure of the helium gas in the heat exchanger where the helium gas is liquefied needs to be maintained higher than the lowest pressure in the expansion T of the refrigerator. If this condition is not met, the liquefaction efficiency will decrease t(
The i-end deteriorates, and liquefaction becomes impossible. The helium gas to be liquefied can also be adiabatically expanded before being cooled and liquefied by a heat exchanger. As a result, the temperature of the helium gas to be liquefied can be further lowered and the temperature of the helium gas can be brought closer to the liquefaction temperature.

The liquefied liquid helium is stored in a liquid helium tank. The helium gas that is vaporized by heat entering from the outside of J3 may be returned to the heat exchanger and liquefied again, or may be returned to the helium gas cylinder.

"Effects" The helium liquefaction method of the present invention includes sending a working medium and another helium gas to a heat exchanger installed between a regenerator and an expansion chamber of a regenerator refrigerator using helium as a working medium. Liquid helium is obtained by cooling helium gas to below its liquefaction temperature in a heat exchanger.

In the helium liquefaction method of the present invention, instead of cooling 1 q of liquid helium using a J-T loop, helium is liquefied by cooling it below the liquefaction temperature in a heat exchanger. For this reason, the single refrigeration unit used is smaller and simpler.

[Example] Fig. 1 shows a system configuration diagram of a cryogenic refrigerator used in the helium liquefaction method of the present invention, and Fig. 2 shows a sectional view of the main parts.

This cryogenic refrigerator consists of a first refrigeration device 1 that extracts cold using a reverse Stirling cycle, a second refrigeration device 2 that extracts cold with even lower humidity using a reverse Stirling cycle, and a helium supply bag [3]. ing.

The first frozen til11 uses helium as a working medium, and the first
In a normal Stirling refrigerator that has two expansion chambers, an expansion chamber 11 and a second expansion chamber 12, a two-stage piston (not shown) for compression is slidably fitted into a two-stage cylinder 13, and the piston and the cylinder 13 form the first expansion chamber 11 and the 21st expansion chamber 12 whose volumes vary.

This first refrigeration system u1 includes a compression chamber and a first expansion chamber 1 (not shown).
It has a heat radiation part (not shown) and a first cold storage chamber between the first expansion chamber 11 and the second expansion chamber 12, and further has a second cold storage chamber (not shown) between the first expansion chamber 11 and the second expansion chamber 12. Then, a drive unit (not shown) reciprocates helium gas between the compression chamber and the first expansion chamber 11 and the second expansion chamber 12, so that the first expansion chamber 11 receives the first cold and the second expansion chamber 1.
It creates a second cold of about 20KV 1 degree in 2020.

The second refrigeration device 2 is a two-stage expansion type Stirling refrigerator having a first cylinder 21, a second cylinder 22, and a third cylinder 23, which also use helium as a production medium.

A first piston 211 is slidably attached to the first cylinder 21, and a compression chamber 215 sealed with a seal 212 is formed at the tip end of the first piston 211. The second cylinder 22 and the third cylinder 23 each have a second piston 221,
The third piston 231 is hv, and a first expansion chamber 225 and a second expansion chamber 235, which are sealed with a seal 222 and a seal 232, are formed at the distal end of each piston 231, respectively.

Note that a first cooling part 014 made of copper that transmits the cold of the first refrigeration system 1 to the first refrigeration unit 1 is in contact with the outer circumferential portion of each cylinder 21, 22, 23 near the seal. Also,
A second cooling member 1 made of copper that conveys the cold of the 2115th chamber 12 of the first refrigeration device 1 is attached to the outer circumference of the tip of the first cylinder 21.
5 are in contact with each other to cool the heat dissipation section 27 provided on the compression chamber 215 side between the compression chamber 215 and the 111th tension chamber 225. Further, between the compression chamber 215 and the first expansion chamber 225, a first
The first cold storage chamber 24 is on the expansion chamber 225 side, the second cold storage chamber 25 is on the first expansion chamber 225 side between the first expansion chamber 225 and the second expansion chamber 235, and the second IllI! A heat exchanger 26 is arranged on the tension chamber 235 side.

This second refrigeration device 2 includes a first piston 211, a second piston 221, and a third piston 23 by a drive section (not shown).
1 and compresses helium, which is a working medium, into the compression chamber 215.
and the first expansion chamber 225 and the second expansion chamber 235 to cool the heat exchanger 26 to 4.2 or less.

The helium supply bag e3 includes a helium gas cylinder 31, a pump 32, a first coil 331 that is wound around the outer circumference of the cylinder 13 that forms the first expansion chamber 11 of the first refrigeration device 1, and a first coil 331 that forms the second expansion chamber 12. A second coil 332 is wound in contact with the outer periphery of the cylinder 13, a third coil 333 is wound in contact with the outer periphery of the first cold storage chamber 24 and the second cold storage chamber 25, the heat exchanger 26 described above, and the liquid Helium tank 34, third coil 333, second coil 332
It is constituted by a loop consisting of a fourth coil 334, a fifth coil 335, and a sixth coil 336, each of which is wound in contact with the outer periphery of the first coil 331.

The helium supply device 3 compresses helium gas in a helium gas cylinder 31 with a pump 32, cools it one after another through a first coil 331, a second coil 332, and a third coil 333, and finally cools the helium gas in a heat exchanger 26 to 4.2 The helium gas is cooled down to liquefy and stored in a liquid helium tank 34. Note that the helium gas that has not been liquefied and the helium gas that has been vaporized by heat from the outside is transferred to the fourth coil 334,
The heat is exchanged in the fifth coil 335 and the sixth coil 336 one after another, losing the cold, and finally returning to the helium gas cylinder 31.

The helium liquefaction method of this example is carried out in this cryogenic cooling A4 machine. That is, the first refrigeration device 1 is operated to cool the heat radiation section 27 of the second refrigeration device 2 to about 20°C, and the second coil 332 of the helium supply device 3 is also cooled to about 20°C.

In addition, the second refrigeration device 2 is driven to supply helium, which is the production medium, to the compression chamber 215, the first expansion chamber 225, and the second expansion chamber 2.
35 to cool the heat exchanger 26 to 4.2 or less. (It is unclear whether it is possible to obtain a temperature lower than the liquefaction temperature of helium by using helium as a working medium, but if the heat dissipation part is cooled to a temperature of about 20°C using a reverse Stirling cycle, the temperature will be lower than 4.2°. ) In this state, the pump 32 of the helium supply device 3 is driven to supply helium gas at a pressure higher than the lowest pressure of the second expansion chamber 235 of the second refrigeration device 2 by 1.6 kg.
Increase to about 2 mcm. Helium gas is then introduced into the heat exchanger 26, liquefied within the heat exchanger 26, and the liquefied liquid helium is stored in the liquid helium tank 34.

Instead of the cryogenic refrigerator used in this example, the helium liquefaction method of the present invention can be carried out using a cryogenic refrigerator *i whose system configuration is shown in FIG. 3.

This cryogenic refrigerator has a Joule-Thompson valve 35 between the third coil 333 and the heat exchanger 26 of the cryogenic refrigerator 212 described above, and the other configurations are the same. In this cryogenic refrigerator, helium gas, which is cooled to a temperature close to 4.2 in the third coil 333 at a relatively high pressure, is adiabatically expanded by passing through the Joule-Thomson valve 35, and the temperature of the helium gas is further increased. descend. This facilitates liquefaction within the heat exchanger 26.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram of the cryogenic device used in the example, and Fig. 2 is a sectional view of the main parts of the cryogenic device.・
・Helium supply device 24...first cold storage chamber 25...second cold storage chamber 26・
... Heat exchanger 27 ... Heat radiation section 34 ... Liquid helium tank 215 ... Compression chamber 225 ... First expansion chamber 23
5...Second expansion chamber patent applicant Hiroshi Okawa, agent for Aisin Seiki Co., Ltd. Figure 2

Claims (5)

[Claims] (1) A compression chamber in which helium as a working medium is compressed, a heat radiation part that releases the heat of compression of the compressed helium, a regenerator communicating with the heat radiation part, and the helium expanded after passing through the regenerator. A helium liquefaction method characterized by cooling and liquefying helium, which is a working medium of the refrigerator, and a separate helium gas using a heat exchanger provided between the regenerator and the expansion chamber of a refrigerator having an expansion chamber. . (2) The helium liquefaction method according to claim 1, wherein the heat dissipation part is cooled by cold of 40K or less. (3) The helium liquefaction method according to claim 1, wherein the helium gas pressure in the heat exchanger in which the helium gas is liquefied is maintained higher than the lowest pressure in the expansion chamber of the refrigerator. (4) The helium liquefaction method according to claim 1, wherein the helium gas to be liquefied is adiabatically expanded and introduced into the heat exchanger before being cooled and liquefied by the heat exchanger. (5) The helium liquefaction method according to claim 1, wherein the refrigerator is an inverted Stirling refrigerator.