Apparatus and method for supercritical helium forced flow cooling based on small refrigerators

Abstract

The application discloses a device for providing supercritical helium forced flow cooling working medium based on a small refrigerating machine, which comprises a pre-treatment device, a first-stage pre-cooling device, a second-stage pre-cooling device, a supercooling and liquefaction device, a vacuum pumping device and a vacuum container; the first-stage pre-cooling device, the second-stage pre-cooling device and the supercooling and liquefaction device are located in the vacuum container; the pre-treatment device is located outside the vacuum container; the vacuum pumping device is connected with the vacuum container; the pre-treatment device, the first-stage pre-cooling device, the second-stage pre-cooling device and the supercooling and liquefaction device are sequentially connected, and medium helium forms a circulation among the devices. The application further discloses a method for providing supercritical helium forced flow cooling working medium based on a small refrigerating machine. The application has the advantages that not only normal-pressure liquid helium can be generated, but also supercritical helium cooling working medium can be generated, liquid helium is not needed to be inputted from outside, the cooling time of a low-temperature user is shortened, helium consumption is reduced, and cooling capacity loss and operation cost are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of low temperature and superconducting engineering technology, and in particular to a device and method for providing supercritical helium forced flow cooling working medium based on a small refrigerator. BACKGROUND

[0002] With the development of world economy and the progress of science and technology, large scientific experimental devices based on superconducting magnet technology have also developed rapidly and been widely used. Helium has become an ideal low-temperature working medium for cooling these superconducting magnets due to its stable chemical properties, high specific heat, high thermal conductivity, low density and low critical temperature. The cooling methods of superconducting magnets can be mainly divided into three types: liquid helium immersion cooling, supercritical helium forced flow cooling and refrigerator conduction cooling. Compared with liquid helium immersion cooling and refrigerator conduction cooling, superconducting magnets using supercritical helium forced flow cooling have the following advantages: increased cooling area, reduced helium consumption, reduced risk of overpressure caused by magnet quenching, increased compactness of the magnet system, and greatly reduced equipment development cost.

[0003] The existing device capable of providing helium forced flow cooling working medium adopts a method of inputting liquid helium from the outside, which needs to transfer liquid helium from a liquid helium refrigerator or a liquid helium dewar to the device, cannot operate independently, has a complex structure and a large scale, and will inevitably cause loss of helium and cooling capacity. For example, Chinese patent application WO2023143641A1 discloses a device for providing liquid helium forced flow cooling working medium, which includes a heat load liquid helium tank system, a circulating pump liquid helium tank system, a supercooled helium liquid helium tank system, a device process pipeline and a cold box. Although it can provide forced flow cooling working medium, it needs to input liquid helium from the outside and cannot operate independently.

[0004] With the development of high-temperature superconducting materials, the structure of superconducting magnet systems is becoming increasingly compact. In order to meet the cooling needs of compact superconducting magnets, a device capable of independently providing supercritical helium forced flow cooling working medium needs to be designed and developed.

[0005] The information disclosed in this BACKGROUND section is only intended to increase an understanding of the general context in which the present application can be practiced. It is not admitted that any of the information provided in this section is prior art. SUMMARY

[0006] The technical problem to be solved by the present application is how to solve the problem that the existing device capable of providing helium forced flow cooling working medium adopts a method of inputting liquid helium from the outside, which needs to transfer liquid helium from a liquid helium refrigerator or a liquid helium dewar to the device, cannot operate independently, has a complex structure and a large scale, and will inevitably cause loss of helium and cooling capacity.

[0007] The present application solves the above technical problems by the following technical means:

[0008] The device for providing supercritical helium forced flow cooling working medium based on a small refrigerating machine comprises a pre-treatment device, a first-stage pre-cooling device, a second-stage pre-cooling device, an overcooling and liquefaction device, a vacuum pumping device and a vacuum container.

[0009] The first-stage pre-cooling device, the second-stage pre-cooling device and the overcooling and liquefaction device are located in the vacuum container, the pre-treatment device is located outside the vacuum container, and the vacuum pumping device is connected to the vacuum container.

[0010] The pre-treatment device, the first-stage pre-cooling device, the second-stage pre-cooling device and the overcooling and liquefaction device are sequentially connected, and the medium helium forms a circulation between the pre-treatment device, the first-stage pre-cooling device, the second-stage pre-cooling device and the overcooling and liquefaction device.

[0011] The device can not only generate normal-pressure liquid helium but also generate supercritical helium cooling working medium by means of the two-stage cold energy provided by the small refrigerating machine and the internal circulation system, without inputting liquid helium from outside, so that the cooling time of a low-temperature user is shortened, helium consumption is reduced, and cold energy loss and operation cost are reduced.

[0012] Preferably, the pre-treatment device comprises a gas storage device, a helium purification device and a helium recovery compressor, the outlet end of the gas storage device is connected to the helium purification device, the outlet end of the helium purification device is connected to the input end of the first-stage pre-cooling device, the output end of the first-stage pre-cooling device is connected to the helium recovery compressor, and the helium recovery compressor is connected to the gas storage device.

[0013] Preferably, the pre-treatment device further comprises a flow regulating valve, an inlet gas on-off valve and a return gas on-off valve, the flow regulating valve is connected between the helium storage tank and the helium purification device, the inlet gas on-off valve is connected between the helium purification device and the first-stage pre-cooling device, and the return gas on-off valve is connected between the first-stage pre-cooling devices.

[0014] Preferably, the first-stage pre-cooling device comprises a first-stage heat exchanger, a first-stage cold head heat exchanger and a second-stage heat exchanger, the hot medium inlet of the first-stage heat exchanger is connected to the output end of the pre-treatment device, and the cold medium outlet of the first-stage heat exchanger is connected to the input end of the pre-treatment device.

[0015] The hot medium inlet of the first-stage cold head heat exchanger is connected to the hot medium outlet of the first-stage heat exchanger, the hot medium inlet of the second-stage heat exchanger is connected to the hot medium outlet of the first-stage cold head heat exchanger, and the cold medium outlet of the second-stage heat exchanger is connected to the cold medium inlet of the first-stage heat exchanger.

[0016] Preferably, the second-stage pre-cooling device comprises a second-stage cold head heat exchanger and a third-stage heat exchanger.

[0017] The heat medium outlet of the primary pre-cooling device is connected to the heat medium inlet of the secondary cold head heat exchanger, the heat medium outlet of the secondary cold head heat exchanger is connected to the heat medium inlet of the tertiary heat exchanger, and the cold medium outlet of the cold medium of the tertiary heat exchanger is connected to the cold medium inlet of the primary pre-cooling device.

[0018] Preferably, the supercooling and liquefaction device comprises a supercooling coil heat exchanger, a supercooling helium tank and a throttle valve.

[0019] The heat medium inlet of the supercooling coil heat exchanger is connected to the heat medium outlet of the secondary pre-cooling device, and the supercooling tank is connected to the cold medium inlet of the secondary pre-cooling device.

[0020] The supercooling coil heat exchanger is deeply inserted into the supercooling helium tank, the cooling working medium return gas pipeline is connected to the inlet of the throttle valve, and the outlet pipeline of the throttle valve is connected to the supercooling helium tank.

[0021] Preferably, the other end of the cold coil heat exchanger is connected to a supercritical helium pipeline, a low-temperature user control valve is connected to the supercritical helium pipeline, and a low-temperature user control valve is connected to the cooling working medium return gas pipeline.

[0022] Preferably, the vacuumizing device is connected to the vacuum container and the cooling working medium return gas pipeline and the supercritical helium pipeline.

[0023] The vacuum container and the internal pipeline are also connected to the vacuumizing device, and the pipeline is replaced and the vacuum degree of the vacuum container is maintained before operation.

[0024] Preferably, the primary pre-cooling device, the secondary pre-cooling device and the supercooling and liquefaction device are all wrapped by more than 30 layers of multilayer heat insulation material composed of aluminized film and heat insulation fiber paper.

[0025] The heat leakage of the internal equipment is reduced.

[0026] The application discloses a method for providing supercritical helium forced flow cooling working medium based on a small-sized refrigerator, and the method is characterized in that the device for providing supercritical helium forced flow cooling working medium based on a small-sized refrigerator is used, and the device comprises the following steps.

[0027] The helium gas is purified and impurities are removed by the pre-treatment device to form high-pressure high-purity helium gas, the high-pressure high-purity helium gas passes through the high-pressure side of the primary pre-cooling device and the secondary pre-cooling device, exchanges heat with normal-pressure liquid helium in the supercooling and liquefaction device to form supercritical helium, and supplies the supercritical helium to a low-temperature user; the supercritical helium after heat exchange with the low-temperature user expands to generate normal-pressure liquid helium which is stored in the supercooling and liquefaction device and exchanges heat in the supercooling and liquefaction device to generate helium steam which sequentially flows through the low-pressure side of the primary pre-cooling device and the secondary pre-cooling device, and finally is recovered and compressed to return to the helium gas storage device.

[0028] The application has the advantages that:

[0029] The present application provides two-stage cooling capacity for helium cooling by small refrigerators, so that the device can rely on its internal circulation system to not only produce normal pressure liquid helium, but also generate supercritical helium cooling medium, without inputting liquid helium from the outside, shortening the cooling time of low-temperature users, reducing helium consumption, reducing cooling capacity loss and operation cost.

[0030] The vacuum container and the internal pipeline are also connected to a vacuum device for vacuum replacement of the pipeline and maintenance of the vacuum degree of the vacuum container before operation.

[0031] The first-stage pre-cooling device, the second-stage pre-cooling device, and the supercooling and liquefaction device are each wrapped with more than 30 layers of multilayer thermal insulation material composed of aluminized film and thermal insulation fiber paper to reduce the heat loss of the internal equipment. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a structure diagram of the device for providing supercritical helium forced flow cooling medium based on small refrigerators according to an embodiment of the present application;

[0033] Numbering in the figure:

[0034] 1, pre-treatment device; 11, gas storage equipment; 12, flow regulating valve; 13, helium purification equipment; 14, inlet valve; 15, return valve; 16, helium recovery compressor; 2, first-stage pre-cooling device; 21, first-stage heat exchanger; 22, first-stage cold head heat exchanger; 23, second-stage heat exchanger; 3, second-stage pre-cooling device; 31, second-stage cold head heat exchanger; 32, third-stage heat exchanger; 4, supercooling and liquefaction device; 41, supercooling coil heat exchanger; 42, supercooling helium tank; 43, throttle valve; 44, low-temperature user inlet control valve; 45, low-temperature user outlet control valve; 5, vacuum device; 6, vacuum container. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0036] Embodiment one:

[0037] As Figure 1As shown, the device for providing supercritical helium forced flow cooling working medium based on a small refrigerator comprises a pretreatment device 1, a first-stage precooling device 2, a second-stage precooling device 3, an overcooling and liquefaction device 4, a vacuum pumping device 5 and a vacuum container 6, the vacuum container 6 is internally provided with the first-stage precooling device 2, the second-stage precooling device 3 and the overcooling and liquefaction device 4 which are in communication with each other, the pretreatment device 1 is arranged outside the vacuum container 6, the output end of the pretreatment device 1 is connected with the first-stage precooling device 2, and the vacuum pumping device 5 is further arranged outside the vacuum container 6 and used for maintaining the vacuum degree inside the vacuum container 6.

[0038] The pretreatment device 1 comprises a gas storage equipment 11, a flow regulating valve 12, a helium gas purification equipment 13, an inlet gas switch valve 14, a return gas switch valve 15 and a helium gas recovery compressor 16, the gas storage equipment 11, the flow regulating valve 12, the helium gas purification equipment 13 and the inlet gas switch valve 14 are sequentially connected with the input end of the first-stage precooling device 2, the output end of the first-stage precooling device 2 is sequentially connected with the return gas switch valve 15 and the helium gas recovery compressor 16, and the helium gas recovery compressor 16 is connected with the gas storage equipment 11.

[0039] Specifically, the gas storage equipment 11 is used for storing helium gas, the gas storage equipment 11 and the helium gas purification equipment 13 are communicated through a pipeline, the flow regulating valve 12 is arranged in the middle of the pipeline, when the flow regulating valve 12 between the gas storage equipment 11 and the helium gas purification equipment 13 is opened, the raw gas stored in the gas storage equipment 11 is transported to the helium gas purification equipment 13 through the pipeline, and the oil, water, carbon dioxide and nitrogen and other impurity gases in the helium gas are removed through the helium gas purification equipment 13. Then, the helium gas can enter the first-stage precooling device 2 by opening the inlet gas switch valve 14.

[0040] The first-stage precooling device 2 comprises a first-stage heat exchanger 21, a first-stage cold head heat exchanger 22 and a second-stage heat exchanger 23, the first-stage heat exchanger 21, the first-stage cold head heat exchanger 22 and the second-stage heat exchanger 23 are all arranged in the vacuum container 6, the hot medium inlet of the first-stage heat exchanger 21 is connected with the output end of the pretreatment device 1, specifically the output end of the inlet gas switch valve 14, the cold medium outlet of the first-stage heat exchanger 21 is connected with the input end of the pretreatment device 1, specifically the inlet end of the return gas switch valve 15. The hot medium inlet of the first-stage cold head heat exchanger 22 is connected with the hot medium outlet of the first-stage heat exchanger 21, the first-stage cold head of the small refrigerator provides preliminary cooling capacity for the helium gas, the hot medium inlet of the second-stage heat exchanger 23 is connected with the hot medium outlet of the first-stage cold head heat exchanger 22, and the cold medium outlet of the second-stage heat exchanger 23 is connected with the cold medium inlet of the first-stage heat exchanger 21.

[0041] The secondary pre-cooling device 3 comprises a secondary cold head heat exchanger 31 and a tertiary heat exchanger 32, both of which are arranged in the vacuum container 6, the heat medium inlet of the secondary cold head heat exchanger 31 is connected to the output end of the secondary heat exchanger 23 of the primary pre-cooling device 2, the secondary cold head of the small refrigerating machine provides preliminary cooling capacity for the helium, the heat medium inlet of the tertiary heat exchanger 32 is connected to the heat medium outlet of the secondary cold head heat exchanger 31, and the cold medium outlet of the tertiary heat exchanger 32 is connected to the cold medium inlet of the secondary heat exchanger 23.

[0042] The supercooling and liquefaction device 4 comprises a supercooling coil heat exchanger 41, a supercooling helium tank 42, a throttling valve 43, an inlet low-temperature user control valve 44 and an outlet low-temperature user control valve 45, the heat medium inlet of the supercooling coil heat exchanger 41 is connected to the output end of the tertiary heat exchanger 32 of the secondary pre-cooling device 3, the helium exchanges heat with the normal-pressure liquid helium in the supercooling helium tank 42 through the supercooling coil heat exchanger 41 to form supercritical helium, the inlet low-temperature user control valve 44 is opened, and the supercritical helium is provided to the low-temperature user through the supercritical helium pipeline; the throttling valve 43 is opened, and the low-temperature user is connected to the supercooling helium tank 42 through the cooling working medium return pipeline and the throttling valve 43, the liquid helium generated after throttling is stored in the supercooling helium tank 42 to provide cooling capacity for the supercooling coil heat exchanger 41; the helium evaporated from the supercooling helium tank 42 flows through the tertiary heat exchanger 32, the secondary heat exchanger 23 and the primary heat exchanger 21 in sequence to provide cooling capacity for the hot helium, thereby greatly reducing the consumption of cooling capacity.

[0043] The supercooling and liquefaction device 4 realizes the generation of supercritical helium and normal-pressure liquid helium.

[0044] The vacuum container 6 and the internal pipeline (the internal pipeline comprises the cooling working medium return pipeline) are further connected to the vacuumizing device 5, the vacuumizing device 5 comprises a vacuum pump set 51 and a vacuum valve 52 arranged on the vacuum pipeline, and the pipeline is evacuated and replaced and the vacuum degree of the vacuum container 6 is maintained before operation. The equipment placed in the vacuum container 6 is wrapped with 30 layers of multilayer heat insulation material composed of aluminized film and heat insulation fiber paper to reduce the heat leakage of the internal equipment.

[0045] The working principle of the embodiment is that the helium stored in the helium storage equipment 11 is delivered to the helium purification equipment 13 through the pipeline, gas impurities in the helium are removed to form high-pressure high-purity helium.

[0046] The high-pressure high-purity helium sequentially passes through the primary heat exchanger 21, the primary cold head heat exchanger 22 and the secondary heat exchanger 23 to be preliminarily heat-exchanged and cooled by the return flow of cold helium and the primary cold head of the small refrigerating machine, and then sequentially passes through the secondary heat exchanger 23, the secondary cold head heat exchanger 31 and the tertiary heat exchanger 32 to be further heat-exchanged and cooled by the return flow of cold helium and the secondary cold head of the small refrigerating machine.

[0047] The high-pressure high-purity helium stream passes through the cold coil heat exchanger 41 and exchanges heat with the normal-pressure liquid helium in the supercooled helium tank 42 to form supercritical helium, which is provided to the low-temperature user through the low-temperature user control valve 44. The supercritical helium after heat exchange with the low-temperature user flows through the throttling valve 43 to produce normal-pressure liquid helium stored in the supercooled helium tank 42 through throttling expansion. The helium vapor produced after the normal-pressure liquid helium exchanges heat with the supercooled coil heat exchanger 41 successively flows through the low-pressure side of the three-stage heat exchanger 32, the two-stage heat exchanger 23 and the one-stage heat exchanger 21 to provide cold energy for the hot helium gas. Finally, the helium gas flows into the helium storage device through the gas return switch valve 15 and the helium gas recovery compressor 16.

[0048] The two-stage cold energy provided by the small-sized refrigerator in the embodiment is used to cool the helium gas, so that the device can rely on the internal circulation system to not only produce normal-pressure liquid helium but also generate supercritical helium cooling medium, without the need to input liquid helium from the outside, thereby shortening the cooling time of the low-temperature user, reducing the helium consumption, and reducing the cold energy loss and operation cost.

[0049] Embodiment Two

[0050] In the embodiment, the one-stage heat exchanger 21, the two-stage heat exchanger 23 and the three-stage heat exchanger 32 are all plate-fin heat exchangers.

[0051] The one-stage cold head heat exchanger 22, the two-stage cold head heat exchanger 31 and the supercooled coil heat exchanger 41 are all coil or fin heat exchangers.

[0052] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limit the same. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features. Such modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. Apparatus for providing supercritical helium forced flow cooling of a working fluid based on a small scale refrigerator, characterised in that, The device comprises a pre-treatment device, a first-stage pre-cooling device, a second-stage pre-cooling device, a super-cooling and liquefaction device, a vacuumizing device, and a vacuum container. The first-stage pre-cooling device, the second-stage pre-cooling device, and the super-cooling and liquefaction device are located in the vacuum container, the pre-treatment device is located outside the vacuum container, and the vacuumizing device is connected to the vacuum container. The pre-treatment device, the first-stage pre-cooling device, the second-stage pre-cooling device, and the super-cooling and liquefaction device are connected in sequence, and the medium helium forms a circulation among the pre-treatment device, the first-stage pre-cooling device, the second-stage pre-cooling device, and the super-cooling and liquefaction device. The super-cooling and liquefaction device comprises a super-cooling coil heat exchanger, a super-cooling helium tank, and a throttle valve; the hot medium inlet of the super-cooling coil heat exchanger is connected to the hot medium outlet of the second-stage pre-cooling device; the super-cooling helium tank is connected to the cold medium inlet of the second-stage pre-cooling device; the super-cooling coil heat exchanger is deeply located in the super-cooling helium tank; the cooling working medium return gas pipeline is connected to the inlet of the throttle valve; and the outlet pipeline of the throttle valve is connected to the super-cooling helium tank.

2. The device for providing supercritical helium forced-flow cooling of a working substance based on a small-sized refrigerator according to claim 1, characterized in that, The pre-treatment device comprises a gas storage device, a helium gas purification equipment, and a helium gas recovery compressor; the outlet end of the gas storage device is connected to the helium gas purification equipment; the outlet end of the helium gas purification equipment is connected to the input end of the first-stage pre-cooling device; the output end of the first-stage pre-cooling device is connected to the helium gas recovery compressor; and the helium gas recovery compressor is connected to the gas storage device.

3. The device for providing supercritical helium forced-flow cooling of a working substance based on a small-sized refrigerator according to claim 2, characterized in that, The pre-treatment device further comprises a flow regulating valve, an inlet gas on-off valve, and a return gas on-off valve; the flow regulating valve is connected between the helium gas storage tank and the helium gas purification equipment; the inlet gas on-off valve is connected between the helium gas purification equipment and the first-stage pre-cooling device; and the return gas on-off valve is connected between the first-stage pre-cooling devices.

4. The device for providing supercritical helium forced-flow cooling of a working substance based on a small-sized refrigerator according to claim 1, characterized in that, The first-stage pre-cooling device comprises a first-stage heat exchanger, a first-stage cold head heat exchanger, and a second-stage heat exchanger; the hot medium inlet of the first-stage heat exchanger is connected to the output end of the pre-treatment device; and the cold medium outlet of the first-stage heat exchanger is connected to the input end of the pre-treatment device. The hot medium inlet of the first-stage cold head heat exchanger is connected to the hot medium outlet of the first-stage heat exchanger; the hot medium inlet of the second-stage heat exchanger is connected to the hot medium outlet of the first-stage cold head heat exchanger; and the cold medium outlet of the second-stage heat exchanger is connected to the cold medium inlet of the first-stage heat exchanger.

5. The device for providing supercritical helium forced-flow cooling of a working substance based on a small-sized refrigerator according to claim 1, characterized in that, The second-stage pre-cooling device comprises a second-stage cold head heat exchanger and a third-stage heat exchanger. The hot medium outlet of the first-stage pre-cooling device is connected to the hot medium inlet of the second-stage cold head heat exchanger; the hot medium outlet of the second-stage cold head heat exchanger is connected to the hot medium inlet of the third-stage heat exchanger; and the cold medium outlet of the third-stage heat exchanger is connected to the cold medium inlet of the first-stage pre-cooling device.

6. The device for providing supercritical helium forced-flow cooling of a working substance based on a small-sized refrigerator according to claim 1, characterized in that, The other end of the cold coil heat exchanger is connected to a supercritical helium pipeline; an inlet low-temperature user control valve is connected to the supercritical helium pipeline; and an outlet low-temperature user control valve is connected to the cooling working medium return gas pipeline.

7. The device for providing supercritical helium forced-flow cooling of a working substance based on a small-sized refrigerator according to claim 6, characterized in that The vacuumizing device is connected to the vacuum container, the cooling working medium return gas pipeline, and the supercritical helium pipeline.

8. The apparatus for providing supercritical helium forced-flow cooling of a working substance based on a small-sized refrigerator according to claim 1, characterized in that, The first-stage pre-cooling device, the second-stage pre-cooling device, and the super-cooling and liquefaction device are each wrapped with more than 30 layers of multi-layer heat insulation material composed of aluminized film and heat insulation fiber paper.

9. A method of providing supercritical helium forced flow cooling of a working fluid based on a small scale refrigerator, characterized in that, The device for providing supercritical helium forced flow cooling working medium based on the small-sized refrigerator according to any one of claims 1-8 comprises the following steps: The pretreatment device purifies and removes impurities from the helium to form high-pressure high-purity helium. The high-pressure high-purity helium passes through the high-pressure side of the first-stage pre-cooling device and the second-stage pre-cooling device, exchanges heat with the normal-pressure liquid helium in the supercooling and liquefaction device to form supercritical helium, and supplies the supercritical helium to the low-temperature user. The supercritical helium after heat exchange with the low-temperature user expands to generate normal-pressure liquid helium, which is stored in the supercooling and liquefaction device and exchanges heat in the supercooling and liquefaction device to generate helium steam, which successively flows through the low-pressure side of the first-stage pre-cooling device and the second-stage pre-cooling device, and finally is recovered and compressed back to the helium storage device.

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