JP3496326B2 - Helium liquefaction refrigeration equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helium liquefaction refrigeration system used for cooling a cooled object such as a superconducting device with liquefied helium. 2. Description of the Related Art FIG. 2 shows an example of a conventional helium liquefaction refrigeration system of the nitrogen-helium binary refrigeration type, which is liquefied to a helium liquefaction refrigerator 1 via a liquefied nitrogen helium heat exchanger 2. A nitrogen cooling device 3 is connected. The helium liquefaction refrigerator 1 includes a liquefaction channel 7 for guiding a liquefaction helium gas 5 from a compressor outlet channel 4A of a helium compressor 4 to a helium container (helium dewar) 6.
And a container return flow path 9 for returning the container reflux helium gas 8 from the helium container 6 to the compressor inlet flow path 4B of the helium compressor 4. The liquefaction flow path 7 and the container return flow path 9
Between the multi-stage refrigeration heat exchangers 10a, 10
b, 10c, 10d, 10e and 10f are provided, and the liquefied nitrogen helium heat exchanger 2 is provided at a position farthest from the helium container 6. The helium 11 for cooling from the helium container 6 is supplied to a cooled body 13 such as a superconducting coil of a superconducting device through a feed passage 12 to cool the cooled body 13 and to be cooled by cooling. The warmed circulating helium gas 14 to be cooled is returned to the compressor inlet flow path 4B together with the circulating vessel helium gas 8 via the cooled body circulating flow path 15 and the switching valve 16. . In FIG. 2, a part of the liquefied helium gas 5 at the outlet of the refrigerating heat exchanger 10a in the liquefaction flow path 7 is guided to an expansion turbine 18 via an on-off valve 17 to be adiabatically expanded. Cold was obtained, and the refrigeration heat exchanger 10c was cooled by the cold, and further led to the expansion turbine 20 via the on-off valve 19 and adiabatically expanded to obtain the cold. At the outlet of the refrigerating heat exchanger 10e of the container reflux channel 9, a cooling channel 21 for mixing with the container reflux helium gas 8 is provided, and the liquefaction helium gas 5 of the liquefaction channel 7 is cooled by the cooling. Cooling is performed by 10d, 10c,... Further, the cooling medium return flow path 15 of the cooling medium return helium gas 14 from the cooling target body 13 is connected to the inlets of the heat exchangers 2, 10 a to 10 f of the vessel return flow path 9. A branch channel 22 is provided, and an on-off valve 23 is provided in each of the branch channels 22. On the other hand, the helium compressor 4 has a problem that the impeller is damaged when a helium gas having a large mass is introduced at a low temperature. Helium gas 14
A heater 24 is provided which is heated to a normal temperature by a heating medium 26 such as water or air, so that the helium gas guided to the helium compressor 4 is heated to a temperature near normal temperature (303K). . When the helium liquefaction refrigeration apparatus is started, first, the helium compressor 4 is driven to circulate helium gas to the helium vessel 6 through the liquefaction flow path 7 and the vessel return flow path 9, and the liquefied nitrogen cooling apparatus 3 is operated. Is driven to cool the helium gas circulating through the liquefied nitrogen helium heat exchanger 2 by the liquid nitrogen 25. The switching valve 16 of the cooling element recirculation flow path 15 is opened with the on-off valve 23 of the branch flow path 22 closed.
Cooling helium 11 from helium container 6 is cooled
3, the cooled object 13 is cooled, and the cooled helium gas 14 heated by cooling is cooled by the container reflux helium gas 8 from the container reflux channel 9 of the helium liquefaction refrigerator 1.
At the same time, the helium gas is led to the heater 24 to be heated to around the room temperature, and the helium gas at the room temperature is led to the helium compressor 4. The helium gas circulating in the helium liquefaction refrigerator 1 is cooled by the liquefied nitrogen cooling device 3 from a temperature of around 303K (normal temperature) to a temperature of around 80K. Next, when the on-off valve 17 is opened, the liquefied helium gas 5 at the outlet of the freezing heat exchanger 10a of the liquefied flow path 7 is opened.
Is cooled by being adiabatically expanded by being guided to the expansion turbine 18, and the refrigeration heat exchanger 10 c is cooled by the cold, and further guided to the expansion turbine 20 via the on-off valve 19 to be adiabatically expanded. The cold helium gas 5a which has become cold is mixed with the container reflux helium gas 8 at the outlet of the refrigerating heat exchanger 10e of the container reflux channel 9 to liquefy the liquefaction channel 7. The helium gas 5 is supplied to the refrigeration heat exchangers 10d, 10c.
・ ・ Cool by As a result, the liquefied helium gas 5 and the cooled object 13 circulating in the helium liquefaction refrigerator 1 are cooled to a temperature lower than 80 K. At this time, when the temperature of the cooled helium gas 14 from the cooled body 13 becomes lower than 80 K, the switching valve 16 of the cooled body reflux channel 15 is closed, and the heat exchangers 2, 10a Open the on-off valve 23 of the branch flow path 22 connected to the vessel return flow path 9 at the position where the temperature of the vessel return helium gas 8 at the inlet of the inlet 10 to 10 f is substantially the same as the temperature of the cooled body return helium gas 14 Then, the cooled body reflux helium gas 14 is combined with the container reflux helium gas 8 so that the cold heat of the cooled body reflux helium gas 14 is effectively used. As the cooling proceeds further, the temperature of the cooled helium gas 14 to be cooled gradually decreases.
Are sequentially switched to change the position where the cooling target reflux helium gas 14 merges with the container reflux flow path 9.
The liquefied helium gas 5 is liquefied at around 4.4 K and stored in the helium container 6, and the cooling helium 11, which has become liquid thereafter, is supplied to the cooled object 13, and the superconducting coil and the like are cooled to an extremely low temperature of 4.4 K. Becomes cooled. However, in the conventional helium liquefaction refrigeration system, in order to protect the helium compressor 4, the cooled object from the cooled object 13 from 303K to 80K in the initial stage of startup. The reflux helium gas 14 and the container reflux helium gas 8 from the helium liquefaction refrigerator 1
Is heated to a normal temperature by a warming device 24 and is guided to a helium compressor 4 to be compressed. The compressed liquefied helium gas 5 at a normal temperature (or higher) is cooled by liquid nitrogen from the liquefied nitrogen cooling device 3. 25, the liquid nitrogen 2 used for cooling is again cooled to 80K.
5, the time required for cooling becomes longer, and a device for supplying a heating medium 26 such as water or air to the heater 24 and operating power for the device are required. There are problems such as becoming. The present invention has been made in view of the above circumstances, and omits the conventional installation of a heater, and converts the cold heat of the reflux helium gas refluxing to the helium compressor around 80K to 303K to the liquefaction helium gas. An object of the present invention is to provide a helium liquefaction refrigeration system that is effectively used for cooling. SUMMARY OF THE INVENTION The present invention provides a helium liquefaction.
Refrigerator and helicopter installed outside the helium liquefaction refrigerator
And a liquefied nitrogen cooling device.
Arm liquefaction refrigerator, a liquefying helium gas being compressed is supplied from the compressor outlet channel at the helium compressor, connected liquefied nitrogen helium heat exchanger liquid nitrogen cooling device
And a liquefaction channel to be supplied to the helium container via a multi-stage refrigeration heat exchanger, and a container reflux helium gas from the helium container through the refrigeration heat exchanger, and a liquefied nitrogen helium heat exchanger. And a container recirculation flow path that recirculates to the compressor inlet flow path of the helium compressor, and a part of the liquefaction helium gas is taken out and located at a position closer to the helium container than the extraction point of the liquefaction helium gas through an expansion turbine. A cooling channel for mixing with the container reflux helium gas is provided.
In addition , the cooling object return flow path for guiding the cooling target reflux helium gas after cooling the cooling target body with the cooling helium from the helium container is connected to the compressor inlet flow passage together with the container return flow path via a switching valve. A helium liquefaction refrigeration apparatus connected to a flow path, and further connected between the cooled object return flow path and a plurality of locations of the container return flow path by a branch flow path having an on-off valve; Between the compressor inlet flow path and the compressor outlet flow path outside the helium liquefaction refrigerator , the low-temperature container helium gas and the cooled helium gas to be cooled are heated to around room temperature to cool the liquefaction helium gas. The present invention relates to a helium liquefaction refrigeration apparatus comprising a cold heat recovery heat exchanger. The helium gas for liquefaction, which is compressed by the helium compressor at around room temperature, and the helium gas at low temperature and the helium gas at the low temperature of the container are heat-exchanged by the heat exchanger for cold heat recovery. The helium gas guided to the compressor inlet flow path is warmed to around room temperature, the liquefied helium gas from the compressor outlet flow path is cooled to a low temperature, and cold energy is recovered. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the present invention applied to the helium liquefaction refrigeration apparatus shown in FIG. 2 above. The vessel reflux helium gas from the vessel reflux channel 9 of the helium liquefaction refrigerator 1 similar to FIG. 8, a compressor inlet flow path 4B for guiding the cooled body reflux helium gas 14 from the cooled body return flow path 15 used for cooling the cooled body 13 to the helium compressor 4, and a helium compressor The liquefied helium gas 5 and the liquefied helium gas 5 are introduced between a compressor outlet flow passage 4A for guiding the liquefied helium gas 5 compressed in 4 to the liquefied flow passage 7 of the helium liquefaction refrigerator 1. Is provided with a heat exchanger 27 for recovering cold heat, which exchanges heat efficiently. The cold heat recovery heat exchanger 27 is, for example, a plate fin type heat exchanger having a large heat transfer area, and performs heat exchange between the reflux helium gas 8, 14 and the liquefaction helium gas 5 in parallel counterflow. , With a heat exchange efficiency close to 100%. Next, the operation of the above embodiment will be described. The liquefied helium gas 5 compressed by the helium compressor 4 is transferred to the liquefied flow channel 7 of the helium liquefied refrigerator 1 through the cold heat recovery heat exchanger 27 provided in the compressor outlet flow channel 4A. The supplied helium gas 8 is supplied from the container return flow path 9 connected to the helium container 6 of the helium liquefaction refrigerator 1, and the cooled object return flow path 15 is connected to the cooled object 13. The cooled helium gas 14 after cooling the cooled body 13 is supplied to the compressor inlet passage 4B.
Is returned to the helium compressor 4 via the cold-heat recovery heat exchanger 27 provided for. In the cold heat recovery heat exchanger 27, 3
Reflux helium gas at low temperature around 03K to 80K 8,1
The liquefied helium gas 4 is warmed to around room temperature by the liquefied helium gas 5 near room temperature and guided to the helium compressor 4, and the liquefied helium gas 5 is cooled to a low temperature around 303K to around 80K by the reflux helium gas 8,14. As a result, the safety of the helium compressor 4 is secured by this heat exchange, and the cold heat of the reflux helium gas 8, 14 is effectively used for liquefaction of the liquefaction helium gas 5. Therefore, the amount of liquid nitrogen 25 used by the liquefied nitrogen cooling device 3 can be reduced, and the time required for liquefying the liquefied helium gas 5 can be shortened. It should be noted that the present invention is not limited only to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention. According to the helium liquefaction refrigeration apparatus of the present invention described above, a low-temperature reflux helium gas and a helium compressor are provided between the compressor inlet flow passage and the compressor outlet flow passage of the helium compressor. The helium gas for cooling at a low temperature is heated to near room temperature by the helium gas for liquefaction at room temperature because it has a cold heat recovery heat exchanger that exchanges heat with the helium gas for liquefaction near room temperature compressed in step 2. The helium gas is cooled to a low temperature by the refluxing helium gas, so that the safety of the helium compressor can be ensured,
The cooling heat of the refluxing helium gas can be effectively used for the liquefaction of the liquefied helium gas, and the amount of liquid nitrogen used by the liquefied nitrogen cooling device can be reduced,
It is possible to obtain excellent effects such as shortening the time required for liquefying the liquefied helium gas.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing one embodiment of the present invention. FIG. 2 is a flowchart showing an example of a conventional helium liquefaction refrigeration apparatus. [Description of Signs] 1 helium liquefaction refrigerator 2 liquefied nitrogen helium heat exchanger 3 liquefied nitrogen cooling device 4 helium compressor 4A compressor outlet channel 4B compressor inlet channel 5 liquefied helium gas 6 helium container 7 liquefied flow Route 8 Container reflux helium gas 9 Container reflux channel 10a Refrigeration heat exchanger 10b Refrigeration heat exchanger 10c Refrigeration heat exchanger 10d Refrigeration heat exchanger 10e Refrigeration heat exchanger 10f Refrigeration heat exchanger 11 For cooling Helium 13 Cooled body 14 Cooled body recirculated helium gas 15 Cooled body recirculation flow path 16 Switching on-off valve 18 Expansion turbine 20 Expansion turbine 21 Cooling flow path 22 Branch flow path 23 Open / close valve 27 Cold heat recovery heat exchanger

Claims (1)

(57) Claims 1. A helium liquefaction refrigerator and the helium liquefaction cooler
Helium compressor and liquid nitrogen cooling installed outside the freezer
Helium liquefaction refrigerator, wherein the helium liquefaction refrigerator converts the liquefied helium gas compressed by the helium compressor and supplied from a compressor outlet flow path to a liquefied nitrogen cooling device. and nitrogen helium heat exchanger, and flow liquefied is supplied to the helium vessel path through the refrigeration heat exchanger of the multi-stage, the container reflux helium gas from the helium vessel, the heat exchanger for the freezing, and liquid nitrogen helium A helium container from a point where the helium gas is taken out from a point where the liquefied helium gas is taken out through an expansion turbine by extracting a part of the liquefied helium gas through a heat exchanger and a part of a liquefied helium gas taken out from the helium compressor through a heat exchanger; position and a cold flow path to be mixed into a container reflux helium gas at near, object to be cooled reflux after cooling the object to be cooled by the cooling helium from the helium vessel Heriumuga Is connected to the compressor inlet flow path together with the container return flow path via a switching valve, and further, the cooled object return flow path and a plurality of locations of the container return flow path a helium liquefying refrigerating apparatus are connected by the branch flow path having a closing valve between said helium liquefier cold
Between the compressor inlet channel and the compressor outlet channel outside the chiller ,
A helium liquefaction refrigeration apparatus comprising a cold heat recovery heat exchanger that cools a liquefied helium gas by heating a low-temperature container reflux helium gas and a cooled object reflux helium gas to around room temperature.