JP2000266416A - Very low temperature refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a flow rate of a refrigerant, supplied from a compression unit to a refrigerator, throughout a wide range. SOLUTION: A very low temperature refrigerating device 10 comprises a compression unit 12 having a compressor 11 to pressurize a refrigerant through compression, and a refrigerator 13 to realize a very low temperature by a pressurized refrigerant fed from the compression unit. In the device, a route 15A on the high pressure side and a route 15B on the low pressure side of the compression unit are intercoupled through a main bypass piping 24 having a main pressure regulating valve 23. The main pressure regulating valve is opened when a pressure in the route on the low pressure side is reduced to a value lower than a given pressure, and formed in a manner to cause bypass of a refrigerant from the route on the high pressure side to the route on the low pressure side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a superconducting magnet or a semiconductor device, a cooling device for a physical property test device at a very low temperature, a cooling device for condensing liquid helium, or a cryogenic pump used for a cryopump. It relates to a refrigeration system.

[0002]

2. Description of the Related Art Generally, a cryogenic refrigeration system is used for a cryopump that generates high vacuum pressure by condensing or adsorbing gas molecules on a panel cooled to a cryogenic temperature. (Eg 10-20K)
Used in cooling devices such as superconducting magnets and physical property test equipment to keep superconducting magnets and samples at extremely low temperatures (for example, 4K).
Is to be cooled down.

[0003] Such a cryogenic refrigeration system 101 is shown in FIG.
As shown in the figure, a compression unit 10 having a compressor 102
3 and the refrigerator 104 are connected by connecting pipes 105A and 105B. The refrigerant pipe 100 in the compression unit 103 includes a heat exchanger 1 on the discharge side of the compressor 102.
A high-temperature and high-pressure refrigerant (He gas) pressurized by the compressor 102 is heat-exchanged to a normal-temperature high-pressure gas. This high-pressure gas is supplied to the refrigerator 104 and adiabatically expanded, and the low-temperature end 104A of the refrigerator 104 is cooled to a very low temperature.

The refrigerant pipe 100 of the compression unit 103
The discharge side of the compressor 102 is a high-pressure side path 100A, and the suction side of the compressor 102 is a low-pressure side path 100B. A heat exchanger 106 (described above), an oil separator 107, and an adsorber 108 are sequentially arranged in the high-pressure side path 100A. From the high pressure side path 100A to the connection pipe 105A
The refrigerant is supplied to the refrigerator 104 as described above. The buffer tank 109 is connected to the low-pressure side path 100B.
Is arranged. The depressurized refrigerant from the refrigerator 104 is
It is introduced into the low-pressure side path 100B via the connection pipe 105B and returned to the compressor 102.

It is desirable that the above-mentioned compression units 103 can cope with the refrigerators 104 having various capacities including the number thereof.
For that purpose, the flow rate of the refrigerant supplied to the refrigerator 104 needs to be secured in a wide range.

When the refrigerator 104 does not require a sufficient flow rate of the refrigerant to be discharged from the compressor 102 of the compression unit 103, or when the refrigerator 104 is not connected to the compression unit 103, The pressure increases in the high-pressure side path 100A of the compression unit 103. Therefore, in the conventional cryogenic refrigeration apparatus 101, the high pressure side path 100A and the low pressure side path 100B are connected to the differential pressure valve 11
0, and the differential pressure between the high-pressure side path 100A and the low-pressure side path 100B is
0, the high-pressure side path 100
Bypassing the high pressure refrigerant in A to the low pressure side path 100B,
The high-pressure side path 100A is protected from high pressure.

For example, the high-pressure side path 100A is set to 20 kg /
cm ^2, and when connecting the refrigerator 104 to the low-pressure side path 100B and 7 kg / cm ² to the compression unit 103, and the setting value of the differential pressure valve 110 and 15 kg / cm ^2, a high-pressure side path 100A of the compression unit 103 When the pressure at rises for some reason and exceeds 22 kg / cm ² , the differential pressure valve 110 opens. Thereby, the high-pressure side path 100A
The high-pressure refrigerant inside is bypassed to the low-pressure side path 100B,
The pressure in the high-pressure side path 100A is maintained at 22 kg / cm ² .

[0008]

However, in the above-described example, as shown in FIG.
When the pressure of B decreases to about 7 kg / cm ² ,
The refrigerant compressed by the compressor 102 of the compression unit 103 is bypassed from the high-pressure side path 100A to the low-pressure side path 100B, and the flow rate supplied to the refrigerator 104 rapidly decreases. In this way, the compression unit 103
Since the lower limit value of the flow rate of the refrigerant that can be supplied to the compressor 4 is governed by the differential pressure valve 110, the capacity inherent in the compressor 102 may not be able to be utilized. Therefore, the flow rate of the refrigerant supplied from the compression unit 103 to the refrigerator 104 cannot be ensured in a wide range.

For example, if the set value of the differential pressure valve 110 is 15 kg / cm ² as described above,
00A is set to 21 kg / cm ² , and the low pressure side path 100B is set to 5 kg / cm ² and the refrigerator 104 is connected to the compression unit 10.
3, when the differential pressure valve 110 is always open,
The high-pressure refrigerant in the high-pressure side path 100A is bypassed to the low-pressure side path 100B. For this reason, the compression unit 103
Of the high-pressure side path 100A is only 20 kg / cm ² at the maximum, and as a result, the performance of the refrigerator 104 cannot be maximized.

An object of the present invention is to provide a cryogenic refrigeration apparatus capable of ensuring a wide range of the flow rate of a refrigerant supplied from a compression unit to a refrigerator.

[0011]

According to a first aspect of the present invention, there is provided a compression unit having a compressor for compressing and pressurizing a refrigerant, and a refrigerator for realizing an extremely low temperature by the compressed refrigerant from the compression unit. And a cryogenic refrigerator having:
The high pressure side path and the low pressure side path of the compressor unit are connected by a bypass path having a pressure regulating valve, and the pressure regulating valve opens when the pressure of the low pressure side path becomes equal to or lower than a predetermined pressure A. The refrigerant is bypassed from the high-pressure side path to the low-pressure side path.

According to a second aspect of the present invention, in the first aspect of the present invention, the high-pressure side path of the compression unit includes:
A pressure sensor for detecting the pressure of the high-pressure side path is installed, and the high-pressure side path and the low-pressure side path are connected by a sub-bypass path having an on-off valve.
The valve is opened when the pressure detected by the pressure sensor becomes equal to or higher than a predetermined pressure B, and the refrigerant in the high pressure side path is bypassed to the low pressure side path. .

According to a third aspect of the present invention, in the first aspect of the present invention, the high-pressure side path and the low-pressure side path in the compression unit are connected by a sub-bypass path provided with a sub-pressure regulating valve. The sub-pressure regulating valve is configured to open when the pressure in the high-pressure side path becomes equal to or higher than a predetermined pressure B, and to bypass the refrigerant in the high-pressure side path to the low-pressure side path. Is what you do.

The first aspect of the present invention has the following effects.

[0015] The pressure regulating valve provided in the bypass path connecting the high pressure side path and the low pressure side path of the compressor unit includes:
The valve is opened when the pressure of the low-pressure side path becomes equal to or lower than the predetermined pressure A, and bypasses the refrigerant from the high-pressure side path to the low-pressure side path, regardless of the pressure difference between the low-pressure side path and the high-pressure side path, Until the pressure of the low pressure side path decreases to the predetermined pressure A, the refrigerant of the high pressure side path is not bypassed to the low pressure side path,
Since all the refrigerant compressed by the compressor is supplied to the refrigerator, the capacity of the compressor alone can be fully utilized, and as a result, the flow rate of the refrigerant supplied from the compressor unit to the refrigerator can be widened. Can be secured.

The second aspect of the present invention has the following operation.

The high pressure side path and the low pressure side path of the compressor unit are connected by a sub-bypass path provided with an on-off valve,
The on-off valve is configured to open when the pressure detected by the pressure sensor installed in the high-pressure side path becomes equal to or higher than a predetermined pressure B, thereby bypassing the refrigerant in the high-pressure side path to the low-pressure side path. When the pressure of the high-pressure side path rises above the predetermined pressure B, the refrigerant is bypassed from the high-pressure side path to the low-pressure side path, so that the high-pressure side path of this compression unit is moved from high pressure without stopping the compression unit. Can be protected.

The third aspect of the invention has the following operation.

The sub-pressure regulating valve installed in the sub-bypass path connecting the high-pressure side path and the low-pressure side path in the compression unit opens when the pressure in the high-pressure side path becomes equal to or higher than a predetermined pressure B, Since the refrigerant in the high-pressure side path is configured to be bypassed to the low-pressure side path, the refrigerant is bypassed from the high-pressure side path to the low-pressure side path when the pressure in the high-pressure side path increases to a predetermined pressure B or more. The high-pressure path of the compression unit can be protected from high pressure without stopping the compression unit.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

[A] First Embodiment (FIGS. 1 and 2) FIG. 1 is a circuit diagram showing a refrigerant circuit in an embodiment of a cryogenic refrigeration apparatus according to the present invention. The cryogenic refrigeration apparatus 10 according to this embodiment is applied to a cryopump that generates high vacuum pressure by condensing or adsorbing gas molecules on a panel, and cools the panel at a cryogenic temperature (for example, 10 to 20K).
The compressor includes a compression unit 12 having a compressor 11 and a refrigerator 13.

In the compression unit 12, a buffer tank 16 is provided on the suction side (ie, the low-pressure side path 15B) of the refrigerant pipe 15 in which the compressor 11 is disposed, and the discharge side (ie, the high-pressure side path 15A).
A heat exchanger 17, an oil separator 18, and an adsorber 19 are sequentially arranged, and the compressor 11 compresses a refrigerant (for example, He gas) into a high-temperature and high-pressure pressurized refrigerant.

The heat exchanger 17 exchanges the high-temperature and high-pressure refrigerant from the compressor 11 with water or air to produce a normal-temperature high-pressure refrigerant (for example, about 20 kg / cm 2). The oil separator 18 separates oil in the refrigerant used for lubrication and cooling in the compressor 11 and returns the oil to the compressor 11 via the oil return pipe 21. Further, the adsorber 19 adsorbs the oil that has not been completely removed by the oil separator 18 and the volatile components in the oil using activated carbon, and supplies a high-purity refrigerant to the refrigerator 13. The buffer tank 16 absorbs pressure pulsation of the refrigerant generated by suction and discharge of the refrigerant by the refrigerator 13 and guides the pressure pulsation to the compressor 11.

The refrigerating machine 13 is operated at normal temperature and high pressure (for example, about 2
0kg / cm2) and repeated adiabatic expansion,
The cold end 20 is cooled to a cryogenic temperature (eg, about 10-20K). The cold end 20 cools the condensation or adsorption panel of the cryopump.

The refrigerator 13 is connected to the high-pressure path 15A in the refrigerant pipe 15 of the compression unit 12 via the connection pipe 22A, and the high-pressure refrigerant from the high-pressure path 15A is introduced into the refrigerator 13. In addition, the refrigerator 13
The refrigerant pipe 1 of the compression unit 12 via the connection pipe 22B
5, the low-pressure refrigerant (about 5 to 10 kg / cm ² ) expanded in the refrigerator 13 is introduced into the low-pressure side path 15B and returned to the compressor 11.

The internal pressures of the high-pressure path 15A and the low-pressure path 15B are determined by the capacity of the refrigerator 13 and the number of the refrigerators 13. Further, the high-pressure side path 15A and the low-pressure side path 15B are connected by a main bypass pipe 24 as a bypass path having a main pressure adjusting valve 23 as a pressure adjusting valve. Main pressure regulating valve 2
3 is configured to open when the pressure in the low-pressure side path 15B becomes equal to or lower than a predetermined pressure A (for example, 4 kg / cm ² ), and to allow the refrigerant in the high-pressure side path 15A to be bypassed into the low-pressure side path 15B. Is done.

For example, the high pressure side path 15A in the compression unit 12 is set to 21 kg / cm ² and the low pressure side path 15B
Of the refrigerator 13 with a pressure of 5 kg / cm ²
And set the pressure A of the main pressure regulating valve 23 to 4 kg.
/ Cm ² . At this time, since the low pressure side path 15B of the compression unit 12 is higher than the set pressure A of the main pressure regulating valve 23, the main pressure regulating valve 23 does not open, and all the refrigerant compressed by the compressor 11 is frozen. Machine 13
Supplied to

In the cryogenic refrigeration system 10, when the refrigerant leaks or the refrigerator 13 having a small capacity is connected to the compression unit 12, the pressure of the low pressure side path 15B of the compression unit 12 increases the durability of the compression unit 12. In addition, there is a case where a pressure (for example, 3 kg / cm ² ) is desired to be avoided. At this time, the low pressure side path 15 of the compression unit 12
Since the pressure of B becomes lower than the set pressure A (for example, 4 kg / cm ² ) of the main pressure control valve 23, the main pressure control valve 23 is opened, and the refrigerant flows from the high pressure side path 15A to the low pressure side path 15B. Flow, low pressure side path 15B is about 4kg
/ Cm ² . Here, reference numeral 25 in FIG. 1 denotes a safety valve.

Therefore, according to the cryogenic refrigeration system 10 of the above embodiment, the following effects are obtained.

A main bypass pipe 24 connecting the high pressure side path 15A and the low pressure side path 15B of the compression unit 12
The main pressure regulating valve 23 provided on the low pressure side passage 15
The valve is opened when the pressure of B becomes equal to or less than the predetermined pressure A,
Since the refrigerant is bypassed from the high-pressure side path 15A to the low-pressure side path 15B, the low-pressure side path 15B and the high-pressure side path 15A
Irrespective of the pressure difference, the refrigerant in the high-pressure side path 15A is not bypassed to the low-pressure side path 15B until all the pressure in the low-pressure side path 15B decreases to the predetermined pressure A. Since the refrigerant is supplied to the refrigerator 13, the ability of the refrigerator 13 alone can be fully utilized.
As a result, as shown in FIG. 2, the flow rate of the refrigerant supplied from the compression unit 12 to the refrigerator 13 can be ensured in a wider range than the conventional example with respect to the pressure in the low-pressure side path 15 </ b> B. We can show ability to the maximum.

In the above-described embodiment, a pressure sensor (not shown) is installed in the high-pressure side path 15A of the refrigerant pipe 15 in the compression unit 12, and the pressure in the high-pressure side path 15A increases due to refrigerant overcharge or the like. At this time, the pressure sensor may detect this pressure, stop the compression unit 12, and protect the high-pressure side path 15A of the compression unit 12 from high pressure.

[B] Second Embodiment (FIG. 3) FIG. 3 is a refrigerant circuit diagram showing a second embodiment of the cryogenic refrigeration apparatus according to the present invention. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The cryogenic refrigeration system 3 of the second embodiment
0 is connected to the high-pressure side path 15A of the compression unit 34 in addition to the configuration of the cryogenic refrigeration system 10 described above.
A pressure sensor 31 for detecting the pressure in A is installed, and the high-pressure side path 15A and the low-pressure side path 15B are connected by a sub-bypass pipe 33 having an electromagnetic valve 32 as an on-off valve.

The solenoid valve 32 is opened when the pressure in the high-pressure side path 15A detected by the pressure sensor 31 becomes equal to or higher than a predetermined pressure B, and causes the refrigerant in the high-pressure side path 15A to pass through the low-pressure side path 15B. It is configured to bypass to.

Therefore, the cryogenic refrigeration system 30 has the following effects in addition to the effects of the cryogenic refrigeration system 10.

The high pressure side path 15A and the low pressure side path 15B of the compression unit 34 are connected by a sub bypass pipe 33 having an electromagnetic valve 32.
Is configured to open when the pressure detected by the pressure sensor 31 installed in the high-pressure side path 15A becomes equal to or higher than a predetermined pressure B, thereby bypassing the refrigerant in the high-pressure side path 15A to the low-pressure side path 15B. Therefore, when the pressure of the high-pressure side path 15A rises to a predetermined pressure B or more, the refrigerant is bypassed from the high-pressure side path 15A to the low-pressure side path 15B, so that the compression unit 34 is not stopped without stopping the compression unit 34.
Can be protected from the high pressure.

[C] Third Embodiment (FIG. 4) FIG. 4 is a refrigerant circuit diagram showing a cryogenic refrigeration apparatus according to a third embodiment of the present invention. In the third embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The cryogenic refrigeration system 4 of the third embodiment
0 indicates that the high-pressure side path 15A and the low-pressure side path 15B in the compression unit 43 have a sub-bypass pipe 42 having a sub-pressure regulating valve 41 in addition to the configuration of the cryogenic refrigeration system 10.
Are connected by.

The sub-pressure regulating valve 41 opens when the high-pressure side path 15A in the compression unit 43 becomes equal to or higher than the predetermined pressure B, and bypasses the refrigerant in the high-pressure side path 15A into the low-pressure side path 15B. It is configured as follows.

Therefore, the cryogenic refrigeration system 40 of this embodiment has the following effects in addition to the effects of the cryogenic refrigeration system 10 of the first embodiment.

High-pressure side path 1 in compression unit 43
The sub-pressure regulating valve 41 installed in the sub-bypass pipe 42 connecting the 5A and the low-pressure side path 15B is connected to the high-pressure side path 1
The valve opens when the pressure of 5A becomes equal to or higher than the predetermined pressure B,
Since the refrigerant in the high-pressure side path 15A is configured to be bypassed to the low-pressure side path 15B, when the pressure in the high-pressure side path 15A increases to a predetermined pressure B or more, the high-pressure side path 15A
Since the refrigerant is bypassed from A to the low-pressure side path 15B,
The high-pressure path 15A of the compression unit 43 can be protected from high pressure without stopping the compression unit 43.

Although the present invention has been described based on the above embodiment, the present invention is not limited to this.

[0043]

As described above, according to the cryogenic refrigeration system of the present invention, the high pressure side path and the low pressure side path of the compressor unit are connected by the bypass path having the pressure regulating valve. The regulating valve is configured to open when the pressure in the low-pressure side path becomes equal to or lower than a predetermined pressure and to bypass the refrigerant from the high-pressure side path to the low-pressure side path, so that the pressure is supplied from the compression unit to the refrigerator. The flow rate of the refrigerant can be secured in a wide range.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing a first embodiment of a cryogenic refrigeration apparatus according to the present invention.

FIG. 2 is a graph showing a relationship between a pressure in a low pressure side path of a compression unit and a flow rate of a refrigerant supplied from the compression unit to the refrigerator in the cryogenic refrigeration apparatus of FIG.

FIG. 3 is a refrigerant circuit diagram showing a second embodiment of the cryogenic refrigeration apparatus according to the present invention.

FIG. 4 is a refrigerant circuit diagram showing a third embodiment of the cryogenic refrigeration apparatus according to the present invention.

FIG. 5 is a refrigerant circuit diagram showing a conventional cryogenic refrigeration apparatus.

6 is a graph showing a relationship between a pressure in a low pressure side path of a compression unit and a flow rate of a refrigerant supplied from the compression unit to the refrigerator in the cryogenic refrigeration apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cryogenic refrigerator 11 Compressor 12 Compression unit 13 Refrigerator 15 Refrigerant pipe 15A High pressure side path 15B Low pressure side path 23 Main pressure regulating valve (Pressure regulating valve) 24 Main bypass piping (Bypass path) 30 Cryogenic refrigerator 31 Pressure Sensor 32 Solenoid valve (open / close valve) 33 Sub bypass pipe (sub bypass path) 34 Compression unit 40 Cryogenic refrigerator 41 Sub pressure regulating valve 42 Sub bypass pipe (sub bypass path) 43 Compression unit

Claims (3)

[Claims] 1. A cryogenic refrigeration system comprising: a compression unit having a compressor for compressing and pressurizing a refrigerant; and a refrigerator for realizing a cryogenic temperature by the pressurized refrigerant from the compression unit. The high pressure side path and the low pressure side path of the unit are connected by a bypass path having a pressure regulating valve, and the pressure regulating valve opens when the pressure of the low pressure side path becomes equal to or less than a predetermined pressure A, A cryogenic refrigeration apparatus characterized in that the refrigerant is bypassed from the high-pressure side path to the low-pressure side path. 2. A pressure sensor for detecting a pressure of the high-pressure side path is provided on a high-pressure side path of the compression unit.
Further, the high-pressure side path and the low-pressure side path are connected by a sub-bypass path having an on-off valve, and the on-off valve operates when the pressure detected by the pressure sensor becomes a predetermined pressure B or more. The cryogenic refrigeration apparatus according to claim 1, wherein the valve is opened to bypass the refrigerant in the high-pressure side path to the low-pressure side path. 3. The high-pressure side path and the low-pressure side path in the compression unit are connected by a sub-bypass path having a sub-pressure regulating valve. 2. The cryogenic refrigeration apparatus according to claim 1, wherein the valve is opened when the pressure becomes equal to or higher than B and the refrigerant in the high-pressure side path is bypassed to the low-pressure side path. 3.