JPH0875283A - Cryogenic freezing device - Google Patents

Abstract

PURPOSE: To provide a cryogenic freezing device having a superior operating characteristic and further having a superior efficiency. CONSTITUTION: There is provided a cryogenic ejector 2 with cryogenic refrigerant of high pressure fed from a cooling stage 1 being applied as injection gas. This device comprises a cryogenic compressor 3 with a returning cryogenic refrigerant fed from a cooled item 4 being increased up to its middle pressure. Discharted gas of the cryogenic compressor 3 is applied as suction gas for the cryogenic ejector 2. With such an arrangement as above, the gas is increased up to a middle pressure with the cryogenic compressor having a superior operating characteristic and the pressure is further increased with the cryogenic ejector not requiring any external power, so that it is possible to realize the cryogenic freezing device having a superior operating characteristic and a high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic refrigerator, and more particularly to a cryogenic refrigerator suitable for producing a cryogenic refrigerant depressurized to atmospheric pressure or less.

[0002]

2. Description of the Related Art As a conventional cryogenic refrigerator, for example, as described in JP-A-3-244966, a high-pressure cryogenic refrigerant sent from a cooling stage is used as an injection gas,
It is known to have a cryogenic ejector that uses the cryogenic refrigerant returned from the object to be cooled as an intake gas.

[0003]

The above-mentioned prior art has a problem that the cryogenic ejector is mechanically fixed and therefore has little flexibility in operation. Furthermore, in order to absorb the return cryogenic refrigerant flow rate from the cooled object that varies depending on the operation mode of the cooled object and maintain the pressure of the returned cryogenic refrigerant, the injection gas flow rate of the cryogenic ejector is required to be a heat balance. There is a problem that the efficiency of the device is lowered because the flow rate must be increased.

The present invention solves the above problems of the prior art,
It is an object of the present invention to provide a cryogenic refrigeration system which has good driving operability and high efficiency.

[0005]

The above object is to provide a cryogenic compressor for pressurizing the cryogenic refrigerant returned from the object to be cooled, and use the discharge gas of the cryogenic compressor as the suction gas of the cryogenic ejector. Can be achieved by

[0006]

In general, the ejector has a mechanism in which the injection gas is injected at a supersonic velocity from a narrow nozzle, the suction gas is sucked at the supersonic velocity portion, and the pressure is restored at the diffuser portion. Therefore, the ejector can pressurize the intake gas without requiring work from the outside, but has a feature that the intake pressure rises as the intake gas flow rate increases.

On the other hand, the compressor boosts the pressure by giving work from the outside, and has excellent operability.
When the compression ratio becomes large, the required power increases, and when the actual volumetric flow rate decreases, the equipment becomes smaller and the efficiency decreases.

In a cryogenic refrigerator, for example, a helium refrigerator, various operating conditions are required depending on the operation mode of the object to be cooled, and the flow rate of the cryogenic refrigerant returned from the object to be cooled also fluctuates significantly. Further, the helium refrigerating device is characterized in that the actual volumetric flow rate becomes small because it is extremely low temperature (the temperature of liquid helium under atmospheric pressure is 4.2K).

The present invention, as a result of examining these characteristics,
As a cryogenic refrigerator suitable for producing cryogenic refrigerant decompressed under atmospheric pressure, the cryogenic refrigerant returned from the object to be cooled is boosted to an intermediate pressure by a cryogenic compressor with excellent operability and cooled. The discharge gas of the cryogenic compressor is sucked by the cryogenic ejector, which uses the high-pressure cryogenic refrigerant sent from the stage as the injection gas, and a highly efficient cryogenic refrigeration system with good operability can be realized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a cooling stage including a plurality of heat exchangers and a plurality of expansion turbines, 2 is a cryogenic ejector, 3 is a cryogenic compressor, 4 is a cooled object, 5 is a gas-liquid separator, and 6 is a pole. Low temperature ejector inlet valve, 7 liquid helium supply valve, 8
Is a cryogenic compressor outlet valve, 9 is a cryogenic compressor bypass valve,
Reference numeral 10 is a cryogenic compressor bypass line.

Next, the operation of the embodiment of the present invention constructed as above will be described. The high-pressure cryogenic refrigerant supplied from the cooling stage 1 including a plurality of heat exchangers and a plurality of expansion turbines passes through the cryogenic ejector inlet valve 6 to become a jet gas of the cryogenic ejector 2, and in the cryogenic ejector 2. It is mixed with the suction gas, and is brought into a gas-liquid mixed state, and is supplied to the gas-liquid separator 5. The cryogenic helium gas gas-liquid separated by the gas-liquid separator 5 returns to the cooling stage 1, and liquid helium is supplied to the cooled object 4 through the liquid helium supply valve 7. The cryogenic helium gas obtained by cooling and cooling the cooled object 4 is boosted to an intermediate pressure by the cryogenic compressor 3, passes through the cryogenic compressor outlet valve 8 and becomes the suction gas of the cryogenic ejector 2.

The cryogenic ejector inlet valve 6 is adapted to the cryogenic ejector 2 in accordance with various operating conditions of the cryogenic refrigeration system.
It is provided for adjusting the flow rate of the injection gas of. The liquid helium supply valve 7 is provided to control the liquid helium to be supplied in accordance with the heat load of the object to be cooled 4, and also serves as a pressure reducing valve. The cryogenic compressor outlet valve 8 is used for the cryogenic compressor 3
Is provided for closing the line during stoppage, and the cryogenic compressor bypass valve 9 and the cryogenic compressor bypass line 10 are provided.
Are provided for operation without using the cryogenic compressor 3.

The cryogenic compressor 3 corresponds to the cryogenic helium gas flow rate which varies depending on the operation mode of the object to be cooled 4,
The capacity of the cryogenic helium gas is controlled by a control means (not shown) so as to maintain the pressure of the cryogenic helium gas at a predetermined set value (for example, rotation speed control).

As described above in detail, according to the present embodiment, the cryogenic compressor which is excellent in driving operability raises the temperature to the intermediate pressure, and the high pressure cryogenic refrigerant sent from the cooling stage is used as the injection gas. In order to make it as the inhaled gas of the cryogenic ejector,
There is an effect that it is possible to realize a highly efficient cryogenic refrigerating device having good driving operability.

[0015]

EFFECTS OF THE INVENTION According to the present invention, a cryogenic temperature is provided which has a cryogenic ejector which uses a high-pressure cryogenic refrigerant sent from the cooling stage as an injection gas, and which boosts the cryogenic refrigerant returned from an object to be cooled to an intermediate pressure. By having a compressor and using the discharge gas of the cryogenic compressor as the suction gas of the cryogenic ejector, various heat load conditions of the object to be cooled are sucked in by the cryogenic compressor with excellent driving operability, and external Since the cryogenic ejector, which does not require power, sucks in and boosts the gas discharged from the cryogenic compressor, there is an effect that a highly efficient cryogenic refrigeration system can be realized with good operability.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Cooling stage, 2 ... Cryogenic ejector, 3 ... Cryogenic compressor, 4 ... Cooled object, 5 ... Gas-liquid separator.

Claims (6)

[Claims] 1. A cryogenic refrigeration system having a cooling stage including a plurality of heat exchangers and a plurality of expansion turbines for cooling a high pressure gas stream to near a liquefied gas temperature, and an object to be cooled which is cooled with a cryogenic refrigerant. In, a cryogenic ejector that uses the high-pressure cryogenic refrigerant sent from the cooling stage as an injection gas,
A cryogenic refrigerator having a cryogenic compressor for pressurizing a cryogenic refrigerant returned from the object to be cooled, wherein a discharge gas of the cryogenic compressor is a suction gas of the cryogenic ejector. apparatus. 2. A cryogenic refrigerating apparatus, wherein the cryogenic compressor according to claim 1 is a turbo cryogenic compressor. 3. The cryogenic refrigerating apparatus according to claim 1,
A cryogenic refrigerator equipped with a bypass line for a cryogenic compressor. 4. The cryogenic refrigerating apparatus according to claim 1,
A cryogenic refrigeration system comprising a control means for holding the inlet pressure of the cryogenic compressor at a predetermined set value by controlling the capacity of the cryogenic compressor. 5. A cryogenic compressor and a cryogenic ejector used in the cryogenic refrigerating apparatus according to claim 1. 6. An object to be cooled, which is cooled by the cryogenic refrigerating apparatus according to claim 1.