JPH09236344A - Cryogenic refrigeration equipment - Google Patents

Abstract

(57) [PROBLEMS] For precooling and shield refrigerators 26, 40, which are displacer type expanders, and JT refrigerator 48,
When the effect of the refrigerating capacity of the pre-cooling refrigerator 26 on the refrigerating capacity of the JT refrigerator 48 is reduced and the evaporated helium gas in the liquid helium tank Th is cooled to be condensed and liquefied, the tank Th
The helium gas inside is cooled from room temperature to the condensation temperature in a short time. SOLUTION: In a JT refrigerator 48, a high-pressure helium gas from compressors 5 and 8 exchanges heat with low-pressure low-pressure helium gas returning to the compressors 5 and 8 in a four-stage JT heat exchanger 5.
The first JT heat exchanger 51 on the highest temperature side among 1 to 54
After precooling the helium gas after being cooled by the precooling heat exchanger 50 by the heat station 43 of the shield refrigerator 40, the heat station 37 of the precooling refrigerator 26,
Precool at 38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a cryogenic refrigeration system in which a pre-cooling / shielding refrigerator composed of a displacer-driven expander and a JT refrigerator are connected to a compressor.

[0002]

2. Description of the Related Art Conventionally, as a cryogenic refrigerating apparatus of this type, for example, JP-A-7-127936 and JP-A-7-12.
As disclosed in Japanese Patent No. 7937 and Japanese Patent Laid-Open No. 7-127938, a JT refrigerator that expands high-pressure helium gas with a JT valve and a high-pressure helium gas by a reciprocating motion of a displacer to generate an extremely low temperature. And a pre-cooling refrigerator consisting of a displacer-driven expander for pre-cooling the helium gas before Joule-Thomson expansion in the JT refrigerator, and a displacer-driven type that expands high-pressure helium gas by reciprocating motion of the displacer to generate cryogenic temperature With a shield refrigerator consisting of an expander,
The expansion of the helium gas in the JT valve of the JT refrigerator produces a cryogenic level of about 4K, and the cryogenic cooling portion cooled to the cryogenic level by this JT refrigerator is obtained by the shield refrigerator. Also known is a 4K refrigerating device which is designed to provide a heat shield from the outside room temperature level by extremely low temperature cold.

[0003]

By the way, in the above-mentioned conventional one, since the high-pressure helium gas of the JT refrigerator is pre-cooled by the pre-cooling refrigerator, the JT valve expands the Joule-Thomson. The refrigerating capacity of the cooling machine largely depends on the cooling capacity of the pre-cooling refrigerator, and if the refrigerating capacity of the pre-cooling refrigerator decreases due to deterioration of the pre-cooling refrigerator over a long period of time, the refrigerating capacity of the JT refrigerator also decreases. There is.

In the case where the vaporized helium gas in the liquid helium tank is cooled and condensed and liquefied by the cold obtained by a JT refrigerator, for example, the helium gas in the helium tank is cooled from room temperature to the condensation temperature. When cooling and liquefying, only the refrigerating capacity of the pre-cooling refrigerator can be used as the refrigerating capacity of the JT refrigerator, and it takes a long time to store a sufficient amount of liquid helium in the helium tank.

The present invention has been made in view of the above points, and an object thereof is to make good use of the configurations of three types of refrigerators including a pre-cooling refrigerator, a JT refrigerator, and a shield refrigerator, to achieve a JT refrigerator. In addition to reducing the influence of the refrigerating capacity of the pre-cooling refrigerator on the refrigerating capacity of the machine, when the JT refrigerator cools the condensed refrigerant gas in the refrigerant tank to condense and liquefy, the refrigerant gas in the refrigerant tank is condensed from room temperature. It is to be able to cool to the temperature in a short time.

[0006]

In order to achieve the above object, the present invention not only precools a high-pressure refrigerant gas in a JT refrigerator by a precooling refrigerator but also uses a shield refrigerator at a predetermined stage thereof. I also tried pre-cooling.

More specifically, according to the first aspect of the present invention, FIGS.
As shown in FIG. 4, a compressor (5) for compressing the refrigerant gas,
(8) and a multi-stage JT heat exchanger for exchanging heat between the high-pressure refrigerant gas from the compressors (5) and (8) and the low-temperature low-pressure refrigerant gas returning to the compressors (5) and (8) (51) ~ (5
4), and a JT refrigerator (4) having a JT valve (58) for expanding the Joule-Thomson expansion of the high-pressure refrigerant gas cooled by the JT heat exchangers (51) to (54) to generate a cryogenic temperature.
8) and the high pressure refrigerant gas from the compressors (5) and (8) are expanded by the reciprocating motion of the displacer to generate cryogenic temperatures in the heat stations (37) and (38), and the JT refrigerator (48). ), A precooling refrigerator (26) for precooling the refrigerant gas before Joule-Thomson expansion by the heat stations (37), (38);
A heat shield part (S) which is arranged so as to surround a cryogenic cooling part of the T refrigerator (48) and which shields the cryogenic cooling part from the outside in a cooled state, and the compressor (5), ( The high pressure refrigerant gas from 8) is expanded by the reciprocating motion of the displacer to generate cryogenic temperature in the heat station (43), and the heat refrigerator (40) cools the heat shield part (S) by the heat station (43). ) And the JT heat exchangers (51) to (5) of the plurality of stages.
The high pressure refrigerant gas after being cooled by the JT heat exchanger (51) on the highest temperature side of 4) and before being cooled by the heat stations (37), (38) of the precooling refrigerator (26) is Shield refrigerator (40) heat station (4
And a precooling heat exchanger (50) for cooling by 3).

With this structure, the high-pressure refrigerant gas discharged from the compressors (5) and (8) is respectively cooled in the precooling refrigerator (2).
6), shield refrigerator (40) and JT refrigerator (48)
Is supplied to. Then, the heat stations (37) and (38) of the pre-cooling refrigerator (26) and the shield refrigerator (4
At the heat station (43) of 0), reciprocating motion of each displacer generates cold at a cryogenic level, and the heat station (3) of the pre-cooling refrigerator (26).
The high temperature refrigerant gas before the Joule-Thomson expansion in the JT refrigerator (48) is pre-cooled by the cooling in 7) and (38). In the JT refrigerator (48), the compressor (5),
The high-pressure refrigerant gas from (8) has multiple stages of JT heat exchanger (5
In 1) to (54), heat is exchanged with the low-temperature low-pressure refrigerant gas returning to the compressors (5) and (8) to be cooled (precooled). The refrigerant gas thus pre-cooled expands at the JT valve (58) by Joule-Thomson to generate cold at 4K level. Moreover, the heat shield part (S) is cooled by the cold in the heat station (43) of the shield refrigerator (40), and the JT refrigerator (48) is cooled by this heat shield part (S).
The cryogenic cooling part is heat shielded from the outside.

In the pre-cooling heat exchanger (50), after being cooled by the JT heat exchanger (51) on the highest temperature side among the JT heat exchangers (51) to (54) of the plurality of stages, and Heat stations (37), (3) of the pre-cooling refrigerator (26)
The high pressure refrigerant gas before being cooled in 8) is cooled by the heat station (43) of the shield refrigerator (40) together with the heat shield part (S). Therefore, J
Since the high pressure refrigerant gas before being expanded by the JT valve (58) of the T refrigerator (48) is also precooled by receiving the cold from the shield refrigerator (40), the refrigeration of the precooling refrigerator (26) is correspondingly. The capacity is reduced, and the JT refrigerator (48) is less likely to be affected by the refrigerating capacity of the pre-cooling refrigerator (26). Moreover,
Since the number of precooling stages of high-pressure refrigerant gas in the JT refrigerator (48) increases due to the cooling by the shield refrigerator (40), the efficiency of the cryogenic refrigerator can be increased, and the refrigerant tank (Th) for compression and expansion can be When the evaporated refrigerant gas is cooled to be condensed and liquefied, it is possible to shorten the time for cooling the refrigerant gas from room temperature to the condensation temperature in the refrigerant tank (Th).

According to the second aspect of the invention, as shown in FIG.
In the cryogenic refrigeration system of the invention of claim 1, a shield refrigerant tank (Tn) for storing a liquid shield refrigerant for cooling the heat shield part (S), and this shield refrigerant tank (T
and a shield heat exchanger (23) for cooling the heat shield part (S) by the liquid shield refrigerant in n). Then, the shield refrigerator (40) is configured to cool and evaporate the condensed shield refrigerant gas in the shield refrigerant tank (Tn) by its heat station (43). The pre-cooling heat exchanger (50) is configured to exchange heat with the high pressure refrigerant gas with the liquid shield refrigerant in the shield refrigerant tank (Tn).

As a result, the shield refrigerant tank (Tn)
The liquid shield refrigerant stored therein is supplied to the shield heat exchanger (23) to cool the heat shield part (S). Further, the evaporation shield refrigerant gas is cooled and liquefied in the shield refrigerant tank (Tn) by the heat station (43) of the shield refrigerator (40). Then, in the precooling heat exchanger (50), the high pressure refrigerant gas of the JT refrigerator (48) is heat-exchanged with the liquid shield refrigerant in the shield refrigerant tank (Tn) to be cooled. In other words, this JT
The refrigerant gas of the refrigerator (48) is the shield refrigerator (40).
Is indirectly cooled by the heat station (43) via the liquid shield refrigerant in the shield refrigerant tank (Tn). Therefore, the same effect as that of the first aspect of the invention can be obtained.

Particularly, in the present invention, the JT refrigerator (48)
Since the high-pressure refrigerant gas is cooled in the pre-cooling heat exchanger (50) by the liquid shield refrigerant in the shield refrigerant tank (Tn), during the cooldown to bring the cryogenic refrigeration system to the steady operation, the high pressure refrigerant gas is kept in the shield refrigerant tank (Tn). If the liquid shield refrigerant is supplied, the high pressure refrigerant gas of the JT refrigerator (48) can be immediately cooled (pre-cooled) at that time, and the cool down time can be shortened.

According to the third aspect of the invention, as shown in FIG.
In the cryogenic refrigeration system of the invention of claim 1, a shield refrigerant tank (Tn) for storing the liquid shield refrigerant for cooling the heat shield portion (S) is provided. The shield refrigerator (40) is configured to cool and condense the evaporated shield refrigerant gas into the shield refrigerant tank (Tn) by the heat station (43). The pre-cooling heat exchanger (50) is configured to exchange heat with the high pressure refrigerant gas with the liquid shield refrigerant in the shield refrigerant tank (Tn). A shield heat exchanger for cooling the heat shield part (S) with the refrigerant gas cooled by the liquid shield refrigerant in the shield refrigerant tank (Tn) in the precool heat exchanger (50). Connect (23).

With this configuration, the shield refrigerator (40)
The evaporative shield refrigerant gas is cooled and liquefied in the shield refrigerant tank (Tn) by the heat station (43). Further, in the pre-cooling heat exchanger (50), the high pressure refrigerant gas of the JT refrigerator (48) is transferred to the shield refrigerant tank (T
n) The high pressure refrigerant gas that has been cooled by heat exchange with the liquid shield refrigerant in n) and cooled by the liquid shield refrigerant in this precooling heat exchanger (50) is supplied to the shield heat exchanger (23) and cooled. The heat shield part (S) is cooled by the refrigerant gas. In other words, in this invention, this JT
The high pressure refrigerant gas of the refrigerator (48) is transferred to the shield refrigerator (4
0) is indirectly cooled through the liquid shield refrigerant in the shield refrigerant tank (Tn) and then flows to the shield heat exchanger (23) to cool the heat shield part (S). Therefore, the same effect as that of the first aspect of the invention can be obtained.

According to the invention of claim 4, as shown in FIG.
In the cryogenic refrigerator of the invention of claim 1, the precooling heat exchanger (50) shields the high pressure refrigerant gas from the refrigerator (40).
It is configured to directly exchange heat with the heat station (43). Then, in the pre-cooling heat exchanger (50), the shield heat for cooling the heat shield part (S) by the refrigerant gas cooled by the heat station (43) of the shield refrigerator (40) in the pre-cooling heat exchanger (50). Exchanger (23)
Connect.

In this way, in the pre-cooling heat exchanger (50), the high pressure refrigerant gas of the JT refrigerator (48) is heat-exchanged with the heat station (43) of the shield refrigerator (40) to be cooled, and then the shield. The heat shield part (S) is cooled by the cooled high-pressure refrigerant gas supplied to the heat exchanger (23). In other words, in the present invention, the high pressure refrigerant gas of the JT refrigerator (48) is directly cooled from the heat station (43) of the shield refrigerator (40) and then the heat shield part (S) of the shield heat exchanger (23). ) Is cooled, and also in this case, the same effect as the invention of claim 1 can be obtained.

In the fifth aspect of the invention, as shown in FIG. 4, in the cryogenic refrigeration system of the first aspect of the invention, the precooling heat exchanger (50) heats the high pressure refrigerant gas to the heat station of the shield refrigerator (40). It is configured to directly exchange heat with (43). Then, the heat shield part (S) is brought into thermal contact with the heat station (43) of the shield refrigerator (40).

As a result, J
The high pressure refrigerant gas of the T refrigerator (48) is the shield refrigerator (4
It is cooled by exchanging heat with the heat station (43) of 0). In addition, since the heat shield part (S) is in thermal contact with the heat station (43) of the shield refrigerator (40), the heat shield part (S) is changed by the heat station (43) of the shield refrigerator (40). It is cooled directly. Therefore, the same effect as that of the first aspect of the invention can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows the entire configuration of a cryogenic refrigerator (R) according to Embodiment 1 of the present invention.
Is for cooling the superconducting magnet (M) so that the superconducting coil has a cryogenic level, and is attached to a liquid helium tank (Th) for storing liquid helium (refrigerant). Then, the superconducting magnet (M) is dipped in the helium tank (Th) and accommodated therein, and the liquid helium cools and holds the superconducting coil of the magnet (M) below the critical temperature.

The refrigerator (R) comprises a compressor unit (1) and a refrigerator unit (21). A low-stage compressor (5) for sucking and compressing low-pressure helium gas from the low-pressure gas suction port (2) into the compressor unit (1) through a low-pressure pipe (4) having a check valve (3). ) And the helium gas discharged from the low-stage compressor (5) together with the intermediate-pressure helium gas sucked from the intermediate-pressure gas suction port (6) through the intermediate-pressure pipe (7) to further increase the pressure. And a high-stage compressor (8) for compressing the high-pressure compressor (8), and the discharge side of the high-stage compressor (8) is connected to the high-pressure gas discharge port (10) for the refrigerator via the high-pressure pipe (9) for the refrigerator. Further, they are respectively connected to the JT high pressure gas discharge port (12) via the JT high pressure pipe (11) branched from the refrigerator high pressure pipe (9). A JT high-pressure pipe (11) extending from the discharge side of the high-stage compressor (8) to the JT refrigerator (48) is provided with a throttle-fixed type JT flow rate adjusting valve (V) for flow rate adjustment. There is.

(Tb) is a buffer tank for storing helium gas, and one end of a helium gas supply / discharge pipe (15) is connected to the buffer tank (Tb). The other end of the helium gas supply / discharge pipe (15) is branched into a helium gas supply pipe (16) and a helium gas return pipe (17) in the compressor unit (1), and the helium gas supply pipe (16) The end portion is connected to a low pressure pipe (4) between the suction side of the low stage compressor (5) and the check valve (4), and a low pressure control valve (LP) is connected to the helium gas supply pipe (16).
R). This low pressure control valve (LPR)
When the helium gas pressure in the low-pressure pipe (4) drops below a set pressure, it automatically opens as a pilot pressure. With the opening of this low-pressure control valve (LPR), the buffer tank (Tb) is opened. Helium gas is supplied to the low pressure pipe (4) (refrigerant circuit).

On the other hand, the end of the helium gas return pipe (17) is connected to the high pressure pipe (9) for the refrigerator (high pressure pipe for JT (1
1)) connected to this helium gas return pipe (17)
A high pressure control valve (HPR) is arranged in the middle of. This high pressure control valve (HPR) automatically opens as a pilot pressure when the helium gas pressure in the refrigerator high pressure pipe (9) rises above a set pressure. This high pressure control valve (HPR) By opening the valve, the helium gas in the refrigerator high-pressure pipe (9) and the JT high-pressure pipe (11) (refrigerant circuit) is returned to the buffer tank (Tb).

On the other hand, the refrigerator unit (21)
Has a vacuum dewar (D), and this vacuum dewar (D)
The liquid helium tank (Th) is accommodated in the inside in a state of being thermally shielded from the outside by a heat shield plate (S) as a heat shield portion. This heat shield plate (S)
The inside of is a cryogenic cooling portion cooled to a cryogenic level by a JT refrigerator (48) described later.

Further, inside the vacuum dewar (D), a liquid nitrogen tank (Tn) for storing liquid nitrogen as a shield refrigerant is arranged. This liquid nitrogen tank (T
One end of the nitrogen pipe (22) is connected to the bottom of n),
The other end of this nitrogen pipe (22) is opened in the upper part in the same liquid nitrogen tank (Tn), and the nitrogen pipe (22)
And a liquid nitrogen tank (Tn) form a closed-circuit nitrogen circuit.

A shield plate heat exchanger (23) as a shield heat exchanger that is in contact with the heat shield plate (S) in a heat transferable manner is disposed in the middle of the nitrogen pipe (22), The liquid nitrogen in the liquid nitrogen tank (Tn) is supplied to the shield plate heat exchanger (23) through the nitrogen pipe (22), and the shield plate heat exchanger (23) is used to supply liquid nitrogen from the liquid nitrogen tank (Tn). The heat shield plate (S) is cooled to the temperature of liquid nitrogen (about 80 K) by heat exchange with liquid nitrogen,
The liquid helium tank (Th) in the heat shield plate (S) is externally heat shielded, and the nitrogen gas evaporated by heat exchange in the shield plate heat exchanger (23) is returned to the nitrogen tank (Tn). I have to. Incidentally, (24)
Is an atmosphere release valve connected so as to communicate with the liquid nitrogen tank (Tn), and is for discharging excess nitrogen in the liquid nitrogen tank (Tn) to the outside of the vacuum dewar (D).

The refrigerator unit (21) is connected to the high-stage compressor (8) of the compressor unit (1) in parallel with each other in a closed circuit to form a precooling refrigerator (26) and a shield refrigerator (40). And a JT refrigerator (48). The pre-cooling refrigerator (26) compresses and expands the helium gas in order to pre-cool the helium gas (refrigerant) in the JT refrigerator (48). The helium gas pressure to the displacer (not shown) causes the displacer to operate. It is composed of a reciprocating gas pressure drive type GM (Gifford McMahon) cycle expander.

This pre-cooling refrigerator (26) has a hermetic motor head (2) arranged outside the vacuum dewar (D).
7) and a cylinder (28) of large and small two-stage structure connected to the motor head (27). A high-pressure gas inlet (29) and a low-pressure gas outlet (30) are opened in the motor head (27), and the high-pressure gas inlet (29) is connected through a pre-cooling side branch high-pressure pipe (31) and a collective high-pressure pipe (33). The high-pressure gas discharge port (10) for the refrigerator of the compressor unit (1), that is, the discharge side of the high-stage compressor (8), and the low-pressure gas outlet (30) is a pre-cooling side branch intermediate pressure pipe (34) and a collection. Compressor unit (1) through intermediate pressure pipe (36)
Are connected to the intermediate pressure gas suction port (6), that is, to the suction side of the high-stage compressor (8).

On the other hand, the tip of the cylinder (28) penetrates the side wall of the vacuum dewar (D) and extends into the heat shield plate (S) therein, and the tip of the large-diameter portion has a predetermined temperature level. The first heat station (3
7) and the tip of the small diameter portion is formed in the second heat station (38) which is cooled and held at a temperature level lower than that of the first heat station (37).

That is, although not shown here, each heat station (3
Free type displacers (replacers) that partition and form expansion spaces are reciprocally fitted at positions corresponding to 7) and (38). On the other hand, the motor head (2
In 7), a rotary valve that opens and closes each time it rotates,
A valve motor for driving the rotary valve is housed. The rotary valve includes the high pressure gas inlet (29).
The helium gas flowing in from is supplied to each expansion space in the cylinder (28), or the helium gas expanded in each expansion space is switched to be discharged from the low pressure gas outlet (30). Further, the motor head (27) has a cylinder (2
8) An intermediate pressure chamber that communicates with the expansion space inside via an orifice is provided, and a pressure difference is generated between the expansion space and the intermediate pressure chamber by switching the rotary valve, and the displacer is caused by this pressure difference. It is designed to reciprocate. Then, by opening and closing the rotary valve, high-pressure helium gas from the high-stage compressor (8) of the compressor unit (1) is Simon-expanded in each expansion space in the cylinder (28), and the temperature drop accompanying the expansion causes a polar drop. It produces a low level of cold, which is the first in the cylinder (28).
And the second heat stations (37) and (38). That is, in the pre-cooling refrigerator (26), the high-pressure helium gas discharged from the high-stage compressor (8) is adiabatically expanded to lower the temperature of the heat stations (37), (38), and the JT refrigerator (48). ) Later described precooler (5
6) and (57) are pre-cooled, and the expanded intermediate pressure helium gas is returned to the suction side of the high-stage compressor (8) and re-compressed.

On the other hand, the shield refrigerator (40) is of the gas pressure drive type having the same structure as the pre-cooling refrigerator (26), and the motor head (4) is arranged outside the vacuum dewar (D).
1) and a cylinder (42) connected to the motor head (41) and penetrating the side wall of the vacuum dewar (D) and extending inside thereof. A high-pressure gas inlet (44) and a low-pressure gas outlet (45) are opened in the motor head (41), and the high-pressure gas inlet (44) passes through the shield-side branch high-pressure pipe (32) to the collective high-pressure pipe (33). That is, the high pressure gas discharge port (10) for the refrigerator of the compressor unit (1)
(On the discharge side of the high-stage compressor (8)), and the low-pressure gas outlet (45) is connected via the shield side branch intermediate pressure pipe (35) to the above-mentioned collective intermediate pressure pipe (36), that is, the compressor unit (1). Of the intermediate pressure gas (6) (the suction side of the high-stage compressor (8)). On the other hand, the front end of the cylinder (42) is formed in a heat station (43) which is cooled and held at a predetermined temperature level, and this heat station (43) is in the liquid nitrogen tank (Tn).
It faces inside. Then, the shield refrigerator (40) adiabatically expands the high-pressure helium gas discharged from the high-stage compressor (8) to lower the temperature of the heat station (43), and the heat nitrogen of the heat station (43) is reduced. The evaporated nitrogen gas in the tank (Tn) is cooled to be condensed and liquefied, and the expanded intermediate pressure helium gas is returned to the suction side of the high-stage compressor (8) and recompressed.

The JT refrigerator (48) is a refrigerator that expands helium gas by Joule-Thomson in order to generate cold of about 4K. The JT refrigerator (4)
8) is a first JT heat exchanger (51) arranged outside the heat shield plate (S) in the vacuum dewar (D).
And the second to the fourth arranged inside the heat shield plate (S).
It is equipped with JT heat exchangers (52) to (54). Each of the four-stage JT heat exchangers (51) to (54) exchanges heat between helium gases passing through the primary side and the secondary side, respectively. The next side is the high pressure gas discharge port (1) for JT of the compressor unit (1).
2) That is, it is connected to the discharge side of the high-stage compressor (8) via the JT-side high-pressure pipe (55). Also, the second and third
The primary sides of the JT heat exchangers (52), (53) are connected to each other by the first cylinder (28) of the precooling refrigerator (26).
It is connected via a first precooler (56) arranged on the outer periphery of the heat station (37). Similarly, the respective primary sides of the third and fourth JT heat exchangers (53) and (54) are
It is connected via a second precooler (57) arranged on the outer periphery of the second heat station (38). Further, the primary side of the fourth JT heat exchanger (54) is connected to a JT valve (58) for expanding Joule-Thomson of high-pressure helium gas via an adsorber (59). Above JT valve (5
8) is the operation rod (58) from the outside of the vacuum dewar (D).
The opening is adjusted by a). This JT valve (58)
Are communicated with the liquid helium tank (Th) through a liquid helium return pipe (60). The inside of the helium tank (Th) is connected to the secondary side of the fourth JT heat exchanger (54) through a helium gas suction pipe (61). The secondary side of the fourth JT heat exchanger (54) is connected to the third and second JT heat exchangers (5
3), through the respective secondary sides of (52), the first JT heat exchanger (5
1) is connected to the secondary side of the first JT heat exchanger (5
The secondary side of 1) is connected to the low-pressure gas suction port (2) of the compressor unit (1), that is, the suction side of the low-stage compressor (5) via a low-pressure pipe (62).

As a feature of the present invention, the first and second J
The primary sides of the T heat exchangers (51) and (52) are connected to each other in the precooling heat exchanger (5) arranged in the liquid nitrogen tank (Tn).
0). This pre-cooling heat exchanger (5
0) is immersed in the liquid nitrogen in the liquid nitrogen tank (Tn) so that the high pressure helium gas passing through the inside of the precooling heat exchanger (50) exchanges heat with the liquid nitrogen in the liquid nitrogen tank (Tn). Of the first to fourth four-stage JT heat exchangers (51) to (54), after being cooled by the first JT heat exchanger (51) on the highest temperature side, the precooling refrigerator (26 Helium gas before being cooled in the heat stations (37) and (38) of (1) is indirectly passed through liquid nitrogen by the heat station (43) of the shield refrigerator (40) in the precooling heat exchanger (50). I try to cool.

The JT refrigerator (48) is a refrigerant connected in series to both compressors (5) and (8) of the compressor unit (1) via high and low pressure pipes (55) and (62). A circuit is formed, and a part of the refrigerant circuit is opened into the helium tank (Th) through the liquid helium return pipe (60) and the helium gas suction pipe (61), and vaporizes in the helium tank (Th). The helium gas is sucked into the refrigerant circuit from the gas suction pipe (61), and further passed through the secondary sides of the fourth to first JT heat exchangers (54) to (51) to the low-stage compressor (1) of the compressor unit (1). 5) and then sucked into the high-stage compressor (8) and compressed. Further, the high-pressure helium gas compressed by the high-stage compressor (8) is supplied to the first to fourth JT heat exchangers (51) to (54),
The pre-cooling heat exchanger (5) is used to cool by exchanging heat with the low temperature and low pressure helium gas toward the compressor unit (1) side.
0) at the heat station (43) of the shield refrigerator (40) and at the first and second precoolers (56), (5).
After cooling (precooling) in the first and second heat stations (37) and (38) of the precooling refrigerator (26) in 7), the JT valve (58) expands the Joule Thomson to about 4
The liquid helium is liquid K, and the liquid helium is returned to the tank (Th) via the liquid helium return pipe (60).

Next, the operation of the above embodiment will be described. Basically, in a steady state in which the superconducting magnet (M) operates, the superconducting coil is cooled and maintained below the critical temperature by the liquid helium in the helium tank (Th). In addition, the helium gas evaporated in the helium tank (Th) is sucked from the helium gas suction pipe (61) opening in the tank (Th), and the helium gas of the JT refrigerator (48) in the cryogenic refrigerator (R) is discharged. It is supplied to the refrigerant circuit where it is cooled and liquefied by compression and expansion. This liquid helium is returned to the tank (Th) through the liquid helium return pipe (60). By this, the tank (T
A predetermined amount or more of liquid helium is stored in h), and the superconducting coil is stably cooled below the critical temperature.

On the other hand, the liquid nitrogen in the liquid nitrogen tank (Tn) is transferred to the shield plate heat exchanger (2) through the nitrogen pipe (22).
3), the heat shield plate (S) is cooled and held at about 80 K by the shield plate heat exchanger (23), and by this cooling, the liquid helium tank (Th) in the heat shield plate (S) and its The internal superconducting magnet (M), the heat stations (37), (38) of the pre-cooling refrigerator (26), etc. are heat shielded from the outside. Further, liquid nitrogen is evaporated into nitrogen gas by heat exchange with the heat shield plate (S) in the shield plate heat exchanger (23), and the nitrogen gas is passed through the nitrogen pipe (22) to the liquid nitrogen tank (Tn). Return to the upper part.

The operation of the refrigeration system (R) will be described in more detail. When the JT refrigerator (48) is brought into an operating state, the high-stage compressor (8) of the compressor unit (1).
A part of the high-pressure helium gas supplied from the gas expands in each expansion space in the cylinder (28) of the pre-cooling refrigerator (26), and the first heat station (37) causes the predetermined temperature drop due to the temperature drop accompanying the expansion of this gas. The second heat station (38) is cooled to a temperature level lower than the first heat station (37).
The helium gas expanded in the expansion space returns to the compressor unit (1), is sucked into the high-stage compressor (8) through the intermediate pressure pipe (7), and is compressed.

The remaining part of the high-pressure helium gas supplied from the high-stage compressor (8) of the compressor unit (1) is the cylinder (4) in the shield refrigerator (40).
The heat station (43) in the liquid nitrogen tank (Tn) is cooled to a predetermined temperature level by expanding in the expansion space in 2) and the temperature drop accompanying the expansion of this gas. As a result, the nitrogen gas in the upper part of the liquid nitrogen tank (Tn) is cooled and liquefied, and returns to liquid nitrogen. The helium gas expanded in the expansion space in the cylinder (42) of the shield refrigerator (40) also returns to the compressor unit (1) in the same manner as the gas of the pre-cooling refrigerator (26), and its intermediate pressure pipe. It is sucked into the high-stage compressor (8) via (7) and compressed.

On the other hand, the remainder of the high-pressure helium gas discharged from the high-stage compressor (8) in the compressor unit (1) passes through the JT high-pressure pipe (11) and the JT refrigerator (4).
8) After entering the primary side of the first JT heat exchanger (51), where it is heat-exchanged with low-pressure helium gas on the secondary side toward the compressor unit (1) side, and after being cooled from room temperature 300K to a predetermined temperature In the liquid nitrogen tank (Tn), it enters the precooling heat exchanger (50) immersed in the liquid nitrogen and is cooled to the temperature of the liquid nitrogen (about 80 K). This high pressure helium gas then enters the primary side of the second JT heat exchanger (52) where it is heat exchanged with the secondary low pressure helium gas towards the compressor unit (1) side and further cooled. , Enters the first precooler (56) around the first heat station (37) of the precooling refrigerator (26) and is cooled,
The cooled gas enters the primary side of the third JT heat exchanger (53) and is cooled to, for example, about 15 K by heat exchange with the low pressure helium gas on the secondary side, and then the precooling refrigerator (26 ) Second heat station (38) second outer circumference
It enters the precooler (57) and is further cooled. Thereafter, the gas enters the primary side of the fourth JT heat exchanger (54) and is further cooled by heat exchange with the low pressure helium gas on the secondary side,
Then, the JT valve (58) is reached. This JT valve (58)
Then, the high-pressure helium gas is squeezed and subjected to Joule-Thomson expansion to become liquid helium of about 4K, and this liquid helium is supplied to the liquid helium tank (Th) via the liquid helium return pipe (60). The helium gas evaporated in the liquid helium tank (Th) is sucked into the secondary side of the fourth JT heat exchanger (54) through the helium gas suction pipe (61), and the third to first JT heat exchanges are performed. It is sucked into the low-stage compressor (5) and compressed via the respective secondary sides of the vessels (53) to (51).

Therefore, in this embodiment, the first and second JT heat exchangers (5) in the JT refrigerator (48) are used.
A pre-cooling heat exchanger (50) is connected in series between the respective primary sides of the pre-cooling heat exchangers (1) and (52).
Is immersed in the liquid nitrogen in the liquid nitrogen tank (Tn), so in the precooling heat exchanger (50), the first JT on the highest temperature side among the four-stage JT heat exchangers (51) to (54).
The helium gas after being cooled by the heat exchanger (51) is the heat station (43) of the shield refrigerator (40).
Is indirectly cooled through the liquid nitrogen in the liquid nitrogen tank (Tn), and then cooled by the heat stations (37) and (38) of the precooling refrigerator (26). As described above, the high pressure helium gas before being expanded by the JT valve (58) of the JT refrigerator (48) is precooled by receiving the cold from the heat station (43) of the shield refrigerator (40). The refrigerating capacity of the pre-cooling refrigerator (26) is reduced, and the pre-cooling refrigerator (2) having the refrigerating capacity of the JT refrigerator (48) is reduced.
The influence of the refrigerating capacity of 6) is reduced, and the influence of the pre-cooling refrigerator (26) on the JT refrigerator (48) can be reduced.

Moreover, since the number of precooling stages of the high-pressure helium gas in the JT refrigerator (48) is increased by one by cooling with the shield refrigerator (40), the efficiency of the cryogenic refrigerator (R) can be increased as a whole. , JT refrigerator (48)
Thus, when the evaporated helium gas in the liquid helium tank (Th) is cooled and condensed and liquefied, the cooling time for cooling the helium gas in the liquid helium tank (Th) from normal temperature to the condensation temperature can be shortened.

Further, the helium gas of the JT refrigerator (48) is passed through the precooling heat exchanger (50) immersed in the liquid nitrogen in the liquid nitrogen tank (Tn) and cooled by the liquid nitrogen, so that the temperature is extremely low. The liquid nitrogen tank (Tn) is in a cool-down state in which the refrigeration system (R) is switched from operation start to steady operation.
If liquid nitrogen is supplied inside, JT will immediately
The helium gas in the refrigerator (48) can be precooled by liquid nitrogen, and the cooldown time can be shortened.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
In addition, in each of the following embodiments, the same portions as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted), and in the above-described first embodiment, the shield plate heat exchanger (2
3) is connected to a nitrogen pipe (22) that connects the inside and outside of the liquid nitrogen tank (Tn) in a loop, whereas the nitrogen pipe (22) is omitted and a part of the circuit of the JT refrigerator (48) is connected. A shield plate heat exchanger (23) is connected in series.

That is, in this embodiment, the nitrogen pipe (22) in the first embodiment is not provided, and the shield plate heat exchanger (23) is the same as the precooling heat exchanger (50) in the liquid nitrogen tank (Tn). It is connected in series with the primary side of the 2JT heat exchanger (52) so that the heat shield plate (S) is cooled by the high pressure helium gas cooled by the liquid nitrogen in the liquid nitrogen tank (Tn). It has become. Other configurations are the same as those of the first embodiment.

Therefore, in this embodiment, the high pressure helium gas of the JT refrigerator (48) is used as the first JT heat exchanger (5).
After being cooled in 1), it flows into the precooling heat exchanger (50), and in this precooling heat exchanger (50), the liquid nitrogen tank (T
It is cooled by exchanging heat with the liquid nitrogen in n). Then
The high pressure helium gas cooled by the liquid nitrogen is supplied to the shield plate heat exchanger (23), and the heat shield plate (S) is cooled by the cooled high pressure helium gas. Then, the high-pressure helium after cooling the shield plate by the shield plate heat exchanger (23) flows to the primary side of the second JT heat exchanger (52). That is, in this case, after the high-pressure helium gas of the JT refrigerator (48) is indirectly cooled from the heat station (43) of the shield refrigerator (40) via the liquid nitrogen in the liquid nitrogen tank (Tn). It flows into the shield plate heat exchanger (23) to cool the heat shield plate (S). Therefore, the first embodiment
The same operation and effect as described above can be obtained.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
In the second embodiment, the shield refrigerator (40) is shown.
While the heat station (43) indirectly cools the precooling heat exchanger (50) through the liquid nitrogen in the liquid nitrogen tank (Tn), the liquid nitrogen tank (Tn) is omitted. The precooling heat exchanger (50) is directly cooled by the heat station (43) of the shield refrigerator (40).

That is, in this embodiment, the liquid nitrogen tank (Tn) is omitted. The precooling heat exchanger (50) is attached to the heat station (43) of the shield refrigerator (40) so as to directly exchange heat. Further, as in the second embodiment, the pre-cooling heat exchanger (50) is used.
In the precooling heat exchanger (50), the shield refrigerator (4
A shield plate heat exchanger (23) for cooling the heat shield plate (S) by the high pressure helium gas cooled by the heat station (43) of 0) is connected.

In the case of this embodiment, the pre-cooling heat exchanger (5
At 0), the high pressure helium gas of the JT refrigerator (48) is transferred to the heat station (4) of the shield refrigerator (40).
After being cooled by direct heat exchange with 3), it is supplied to the shield plate heat exchanger (23), and the cooled high pressure helium gas cools the heat shield plate (S). Also in this case, the same effect as that of the second embodiment can be obtained.

(Fourth Embodiment) FIG. 4 shows a fourth embodiment of the present invention.
In the third embodiment, the heat station (43) of the shield refrigerator (40) is provided by the precooling heat exchanger (50).
While the helium gas cooled by the above is supplied to the shield plate heat exchanger (23) to cool the heat shield plate (S), the shield plate heat exchanger (23) is omitted and the shield refrigerator is omitted. (40) Heat Station (4
3) The heat shield plate (S) is precooled by the heat exchanger (50).
With this, it is designed to be cooled directly.

That is, in this embodiment, the shield plate heat exchanger (23) in the third embodiment is omitted. Then, the pre-cooling heat exchanger (50) and the heat shield plate (S) are attached to the heat station (43) of the shield refrigerator (40) so as to make heat contact with each other and directly exchange heat. Also in this embodiment, the same operational effects as those of the third embodiment can be obtained.

[0050]

As described above, in the invention of claim 1, the high-pressure refrigerant gas from the compressor is heat-exchanged with the low-temperature low-pressure refrigerant gas returned to the compressor side by the multiple-stage JT heat exchanger. After that, a JT refrigerator that expands the Joule-Thomson to generate a cryogenic temperature and a high-pressure refrigerant gas from the compressor are expanded to generate a cryogenic temperature, and the refrigerant gas before the Joule-Thomson expansion in the JT refrigerator is pre-cooled. A pre-cooling refrigerator consisting of a displacer type expander, a heat shield portion for thermally shielding the cryogenic cooling portion of the JT refrigerator from the outside, and high pressure refrigerant gas from the compressor are expanded to generate cryogenic temperature in the heat station. , A plurality of JT heat exchangers for a cryogenic refrigerating apparatus including a shield refrigerator having a displacer type expander that cools a heat shield portion by the heat station. A precooling heat exchanger for cooling the high pressure refrigerant gas by the heat station of the shield refrigerator after being cooled by the JT heat exchanger on the highest temperature side of the reactor and before being cooled by the heat station of the precooling refrigerator is provided. It was
In the invention of claim 2, a shield heat exchanger for cooling the heat shield part by the liquid shield refrigerant in the shield refrigerant tank is provided, and the evaporation shield refrigerant gas in the shield refrigerant tank is cooled and condensed by the heat station of the shield refrigerator. The precooling heat exchanger is configured to liquefy and indirectly cool the high-pressure refrigerant gas by heat exchange with the liquid shield refrigerant in the shield refrigerant tank. Further, in the invention of claim 3, the heat station of the shield refrigerator cools the evaporated shield refrigerant gas in the shield refrigerant tank to condense and liquefy, and the precooling heat exchanger transfers the high pressure refrigerant gas in the shield refrigerant tank. It is configured to indirectly cool by heat exchange with the liquid shield refrigerant, and a shield heat exchanger for cooling the heat shield part is connected to the pre-cooling heat exchanger so that the high pressure refrigerant gas of the JT refrigerator is shielded by the shield refrigerator. After being indirectly cooled via the liquid shield refrigerant in the shield refrigerant tank, it flows to the shield heat exchanger to cool the heat shield part. Further, in the invention of claim 4, in the pre-cooling heat exchanger, the high pressure refrigerant gas is directly heat-exchanged with the heat station of the shield refrigerator,
By connecting a shield heat exchanger that cools the heat shield part to the pre-cooling heat exchanger, the refrigerant gas of the JT refrigerator is directly cooled by the heat station of the shield refrigerator, and then flows into the shield heat exchanger to provide a heat shield. The parts were cooled. Further, in the invention of claim 5, the pre-cooling heat exchanger is designed to directly exchange heat with the refrigerant gas to the heat station of the shield refrigerator, and to bring the heat shield part into thermal contact with the heat station of the shield refrigerator, and this shield. The heat station of the refrigerator was used to directly cool the heat shield.

Therefore, according to the inventions of claims 1 to 5, the refrigerant gas before being expanded by the JT valve of the JT refrigerator is precooled together with the heat shield portion by the cold in the heat station of the shield refrigerator, and is precooled and frozen. The refrigerating capacity of the JT refrigerator can be reduced by reducing the refrigerating capacity of the JT refrigerator, and the number of precooling stages of the refrigerant gas in the JT refrigerator can be increased by cooling with the shield refrigerator. The efficiency of the cryogenic refrigeration system can be improved, and the cooling time for cooling the evaporated refrigerant gas in the refrigerant tank from room temperature to the condensation temperature can be shortened.

In particular, according to the second aspect of the present invention, when the cryogenic refrigerating apparatus is cooled down to make it operate normally, the refrigerant gas of the JT refrigerator can be immediately cooled by supplying the liquid shield refrigerant into the shield refrigerant tank. , The cool down time can be shortened.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a cryogenic refrigerator according to a first embodiment of the present invention.

FIG. 2 is a view corresponding to FIG. 1 showing a second embodiment.

FIG. 3 is a view corresponding to FIG. 1 showing a third embodiment.

FIG. 4 is a view corresponding to FIG. 1 showing a fourth embodiment.

[Explanation of symbols]

 (R) Cryogenic refrigerator (1) Compressor unit (5), (8) Compressor (21) Refrigerator unit (23) Shield plate heat exchanger (shield heat exchanger) (26) Pre-cooling refrigerator (37) ), (38) Heat Station (40) Shield Refrigerator (43) Heat Station (48) JT Refrigerator (50) Precooling Heat Exchanger (51) to (54) JT Heat Exchanger (58) JT Valve (Th) Liquid helium tank (refrigerant tank) (D) Vacuum dewar (Tn) Liquid nitrogen tank (liquid shield refrigerant tank) (S) Heat shield plate (heat shield part) (M) Superconducting magnet

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masakazu Okamoto 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd.Kanaoka Plant, Sakai Manufacturing Co., Ltd. (72) Katsumi Miura 1304, Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd. Sakai Plant Kanaoka Factory

Claims (5)

[Claims] 1. A compressor (5) for compressing a refrigerant gas,
(8) and a plurality of stages of JT heat exchangers for exchanging heat between the high pressure refrigerant gas from the compressors (5) and (8) and the low temperature low pressure refrigerant gas returning to the compressors (5) and (8) (51) to (54) and the J
The high pressure refrigerant gas cooled by the T heat exchangers (51) to (54) is subjected to Joule-Thomson expansion to generate cryogenic temperature J
A high temperature refrigerant gas from the JT refrigerator (48) having a T valve (58) and the compressors (5) and (8) is expanded by the reciprocating motion of the displacer to the heat stations (37) and (38). A pre-cooling refrigerator (26) for generating a cryogenic temperature and pre-cooling the refrigerant gas before Joule-Thomson expansion in the JT refrigerator (48) by the heat stations (37), (38); and at least the JT refrigerator ( 48) is provided so as to surround the cryogenic cooling portion, and a heat shield portion (S) for thermally shielding the cryogenic cooling portion from the outside in a cooled state, and the compressor (5), (8) The high-pressure refrigerant gas is expanded by the reciprocating movement of the displacer to generate a cryogenic temperature in the heat station (43), and the heat shield part (S) is cooled by the heat station (43). Of the cold refrigerator (40) and the JT heat exchanger (51) on the highest temperature side among the JT heat exchangers (51) to (54) of the plurality of stages and after being pre-cooled refrigerator (26). Heat station (37),
A cryogenic refrigerator comprising: a precooling heat exchanger (50) for cooling the high-pressure refrigerant gas before being cooled by (38) by the heat station (43) of the shield refrigerator (40). 2. The cryogenic refrigeration system according to claim 1, wherein a shield refrigerant tank (Tn) for storing a liquid shield refrigerant for cooling the heat shield part (S), and a liquid shield in the shield refrigerant tank (Tn). A shield heat exchanger (23) for cooling the heat shield part (S) with a refrigerant is provided, and the shield refrigerator (40) uses the heat station (43) thereof to evaporate the shield refrigerant in the shield refrigerant tank (Tn). The precooling heat exchanger (50) is configured to cool the gas to be condensed and liquefied, and the precooling heat exchanger (50) is configured to exchange heat with the liquid shield refrigerant in the shield refrigerant tank (Tn). Characteristic cryogenic refrigerator. 3. The cryogenic refrigeration system according to claim 1, further comprising a shield refrigerant tank (Tn) for storing a liquid shield refrigerant for cooling the heat shield part (S), the shield refrigerator (40) including the shield refrigerant tank (Tn). A heat station (43) is configured to cool the evaporated shield refrigerant gas into the shield refrigerant tank (Tn) to condense and liquefy, and the precooling heat exchanger (50) transfers the high pressure refrigerant gas to the shield refrigerant tank (Tn). ) Is configured to exchange heat with the liquid shield refrigerant inside the precooling heat exchanger (50).
At the heat shield part (S) by the high pressure refrigerant gas cooled by the liquid shield refrigerant in the shield refrigerant tank (Tn)
A cryogenic refrigeration system, to which a shield heat exchanger (23) for cooling the is connected. 4. The cryogenic refrigeration system of claim 1, wherein the precooling heat exchanger (50) is configured to directly exchange high pressure refrigerant gas with the heat station (43) of the shield refrigerator (40). The pre-cooling heat exchanger (50) is connected to the pre-cooling heat exchanger (50).
At the heat station (4) of the shield refrigerator (40)
A cryogenic refrigeration system, to which a shield heat exchanger (23) for cooling the heat shield part (S) with the refrigerant gas cooled by 3) is connected. 5. The cryogenic refrigeration system of claim 1, wherein the precooling heat exchanger (50) is configured to directly exchange the refrigerant gas with the heat station (43) of the shield refrigerator (40). , Shield refrigerator (40) heat station (43)
The cryogenic refrigerating device, wherein the heat shield part (S) is in thermal contact with.