Three-stage refrigerating system based on superconducting magnet

Abstract

The invention relates to the technical field of superconducting magnet refrigeration, in particular to a three-stage refrigeration system based on a superconducting magnet, which is characterized in that a magnet is placed in a heat preservation container, the heat preservation container is arranged in a vacuum low-temperature thermostat, and the vacuum low-temperature thermostat is arranged in a main vacuum low-temperature thermostat; one end of the power source assembly sequentially penetrates through the main vacuum low-temperature thermostat, the vacuum low-temperature thermostat and the heat preservation container to be connected with the magnet, the water cooling module is connected with one side of the power source assembly, and the secondary nitrogen cooling module is communicated with the interior of the main vacuum low-temperature thermostat. And the third-stage helium cooling module communicates with the interior of the heat preservation container, so that according to the technical scheme, the refrigeration speed is high, loss of a refrigeration medium is avoided, cost is low, step-by-step cooling can be achieved, and the system is stable.

Description

Technical Field

[0001] The invention relates to the technical field of superconducting magnet refrigeration, and in particular to a three-stage refrigeration system based on superconducting magnets. Background Art

[0002] When a superconductor is in a superconducting state, its resistance is zero, and electric current can flow through it without loss. At the same time, superconductors are also completely diamagnetic, that is, magnetic fields cannot penetrate superconductors and will be completely repelled from their surface. Based on these characteristics, superconducting magnets can generate strong magnetic fields by passing current through superconducting coils. Due to the zero resistance characteristics of superconductors, current can continue to flow in superconducting coils without energy loss, thereby maintaining the stability of the magnetic field. Products that use superconducting magnets include magnetic resonance imaging, particle accelerators, thermonuclear fusion magnets, colliders, superconducting quantum interference devices, and maglev trains.

[0003] In the prior art, a bipolar cryogenic refrigerator is usually placed in a multi-layer insulation box, with the first cold head placed in the nitrogen cooling layer and the second cold head placed in the helium cooling layer. The connection between the box and the cold head is not easy to seal, which easily leads to waste of cooling medium and increases the number of seals when the cooling capacity is expanded; the cryogenic refrigerator requires non-standard design, the length of the cold head needs to be extended, and it is not easy to manufacture; the box is professionally designed, the cooling capacity is fixed, and the cooling capacity cannot be increased according to demand; the second cold head of the two-stage cold head cryogenic refrigerator has a low cooling capacity and cannot meet the cooling demand.

[0004] Therefore, how to place the refrigeration system outside the multi-layer insulation box to provide sufficient cooling capacity has become a technical problem that needs to be solved urgently by technical personnel in this field. Summary of the invention

[0005] The present invention provides a three-stage refrigeration system based on a superconducting magnet, which is used to solve the problem of how to shorten the disinfection and sterilization time and improve the disinfection and sterilization efficiency.

[0006] The present invention provides a three-stage refrigeration system based on a superconducting magnet, comprising: Power supply components; A heat preservation container; a magnet is placed inside the heat preservation container; A vacuum cryostat, wherein the heat preservation container is arranged inside the vacuum cryostat; A main vacuum cryostat; the vacuum cryostat is arranged inside the main vacuum cryostat, and one end of the power supply assembly passes through the main vacuum cryostat, the vacuum cryostat and the heat preservation container in sequence and is connected to the magnet; A primary water cooling module; the water cooling module is connected to one side of the power supply assembly; A secondary nitrogen cooling module; the secondary nitrogen cooling module is connected to the interior of the main vacuum cryostat; The three-stage helium cooling module is connected to the interior of the thermal insulation container.

[0007] In some of the embodiments, the power supply assembly includes: a power copper busbar and a current lead; one side of the power copper busbar is in contact with the primary water cooling module, one end of the current lead is connected to the power copper busbar, and the other end passes through the main vacuum cryostat, the vacuum cryostat and the insulation container in sequence to be connected to the magnet.

[0008] In some of the embodiments, the primary water cooling module includes: a constant temperature water tank and a water pump; the constant temperature water tank is connected to a pipeline, a water pump is provided on the pipeline, and a part of the pipeline is in contact with a power copper busbar.

[0009] In some of the embodiments, the media used in the secondary nitrogen cooling module and the tertiary helium cooling module are both gaseous.

[0010] In some of the embodiments, a protection pipeline is further included, and the protection pipeline includes: a vent pipe; One end of the vent pipe is located outside, and the other end passes through the main vacuum cryostat, the vacuum cryostat and the insulation container in sequence and is communicated with the interior of the insulation container; a protection component is installed on the vent pipe.

[0011] In some of the embodiments, a vacuum system is further included, wherein the vacuum system is used to evacuate the main vacuum cryostat, the vacuum cryostat and the insulation container.

[0012] In some of the embodiments, a connecting sealed container is further included, one end of which passes through the main vacuum cryostat, the vacuum cryostat and the insulation container in sequence and is connected to the interior of the insulation container, and the other end is located outside the main vacuum cryostat, and the helium-cooled medium in the insulation container flows back to the three-stage helium-cooled module through the connecting sealed container.

[0013] In some of the embodiments, the current lead passes through the connection sealed container and is connected to the magnet.

[0014] In some of the embodiments, a first temperature sensor is installed in the thermal insulation container, the vacuum cryostat and the main vacuum cryostat.

[0015] In some of the embodiments, a layer of radiation cooling material is coated on the inner wall of the thermal insulation container.

[0016] The beneficial effects of the present invention are as follows: 1. Direct helium cooling requires a long refrigeration time, and the helium cooling refrigerator has low energy efficiency. Therefore, the three-stage refrigeration system of the present invention can effectively control the temperature of the power copper bus at the first-stage water cooling module to keep its temperature constant, and will not affect the cooling demand of the second-stage nitrogen cooling module due to changes in ambient temperature. The second-stage nitrogen cooling module can significantly reduce the temperature of the current lead, which can effectively reduce the cooling demand of the three-stage helium cooling module, so that the technical solution of the present invention can control the temperature step by step, and the system runs stably.

[0017] 2. In the prior art, magnet cooling adopts liquid helium and liquid nitrogen immersion. During use, the liquid evaporates and liquid nitrogen and liquid helium must be continuously injected. Liquid nitrogen and liquid helium cannot be recycled. The operation of the magnet equipment requires continuous replenishment of a large amount of liquid nitrogen and liquid helium. The price of liquid helium is high, resulting in high equipment operating costs. The use of the secondary nitrogen cooling module and the tertiary helium cooling module of the present invention can recycle the gaseous refrigerant. Once filled, the equipment can be continuously cooled, and the cost will be greatly reduced.

[0018] 3. The existing magnet refrigeration system still uses a helium cooler for immersion, both of which are maximum cooling capacity. The refrigeration system of the present invention uses a two-stage nitrogen cooling module and a three-stage helium cooling module to cooperate for refrigeration, and the cooling capacity output by the two-stage nitrogen cooling module and the three-stage helium cooling module can be adjusted. By adjusting the refrigeration energy level, the temperature in the insulation container and the main vacuum cryostat is accurately controlled. The superb precision temperature control level makes the system energy-saving effect significant and protects the magnet from being damaged by overheating. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of a three-stage refrigeration system based on superconducting magnets of the present invention; In the accompanying drawings, 100, magnet; 200, power supply assembly; 201, power supply copper bus; 202, current lead; 300, insulation container; 400, vacuum cryostat; 500, main vacuum cryostat; 600, primary water cooling module; 601, constant temperature water tank; 602, water pump; 700, secondary nitrogen cooling module; 701, nitrogen pre-cooling container; 800, tertiary helium cooling module; 900, protection pipeline; 901, ventilation pipe; 902, heat anchor; 903, insulation device; 904, manual purge valve; 905, safety valve; 1000, vacuum system; 1100, connected closed container. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] As described in the background technology, in the prior art, a bipolar cryogenic refrigerator is usually placed in a multi-layer insulation box, the first-stage cold head is placed in the nitrogen cooling layer, and the second-stage cold head is placed in the helium cooling layer. The connection between the box and the cold head is not easy to seal, which easily causes waste of cooling medium and increases the number of seals when the cooling capacity is expanded; the cryogenic refrigerator requires a non-standard design, and the length of the cold head needs to be extended, which is not easy to manufacture; the box is professionally designed, the cooling capacity is fixed, and the cooling capacity cannot be increased according to demand; the second-stage cold head of the two-stage cold head cryogenic refrigerator has a low cooling capacity and cannot meet the cooling demand. How to place the refrigeration system outside the multi-layer insulation box and provide sufficient cooling capacity has become a technical problem that needs to be solved urgently by technicians in this field.

[0022] To solve the above problems, refer to Figure 1 ,The present invention provides a three-stage refrigeration system based on superconducting magnets, a power supply assembly 200; A heat preservation container 300; a magnet 100 is placed inside the heat preservation container 300; A vacuum cryostat 400, wherein the heat preservation container 300 is disposed inside the vacuum cryostat 400; A main vacuum cryostat 500; the vacuum cryostat 400 is disposed inside the main vacuum cryostat 500, and one end of the power supply assembly 200 passes through the main vacuum cryostat 500, the vacuum cryostat 400 and the heat preservation container 300 in sequence to be connected to the magnet 100; A primary water cooling module 600; the water cooling module 600 is connected to one side of the power supply assembly 200; Secondary nitrogen cooling module 700; the secondary nitrogen cooling module 700 is connected to the interior of the main vacuum cryostat 500; A three-stage helium cooling module 800; the three-stage helium cooling module 800 is connected to the interior of the heat preservation container 300; Specifically, the secondary nitrogen cooling module 700 is connected to the interior of the main vacuum cryostat 500 through a pipeline, and the tertiary helium cooling module 800 is connected to the interior of the thermal insulation container 300 through a pipeline, which solves the problem of difficult sealing between the box body and the cold head. The technical solution of the present invention will not cause leakage of the cooling medium, and effectively reduces the cost.

[0023] Preferably, the power supply assembly 200 includes: a power copper bus 201 and a current lead 202; one side of the power copper bus 201 is in contact with the primary water cooling module 600, one end of the current lead 202 is connected to the power copper bus 201, and the other end passes through the main vacuum cryostat 500, the vacuum cryostat 400 and the insulation container 300 in sequence to be connected to the magnet 100.

[0024] Preferably, the primary water cooling module 600 comprises: a constant temperature water tank 601 and a water pump 602; the constant temperature water tank 601 is connected to a pipeline, a water pump 602 is provided on the pipeline, and a part of the pipeline is in contact with the power copper bus 201; Specifically, the constant temperature water in the constant temperature water tank 601 is continuously extracted by the water pump 602 to pre-cool the power copper bus 201. The used constant temperature water will flow back to the constant temperature water tank 601 for recycling. At the same time, an insulating film is provided on the surface of the power copper bus 201 to improve safety.

[0025] Preferably, the media used in the secondary nitrogen cooling module 700 and the tertiary helium cooling module 800 are both gaseous.

[0026] Specifically, the gaseous refrigerant has a faster flow rate than the liquid refrigerant, which can remove heat from the box faster and has a higher cooling efficiency. Furthermore, since the cooling capacity output by a single compressor is insufficient for refrigeration of superconducting magnets, the secondary nitrogen cooling module 700 and the tertiary helium cooling module 800 in the present invention both include a plurality of compressors, and a temperature sensor is installed at the output end of each compressor for real-time temperature monitoring. In addition, temperature sensors are installed on the gas medium outlet pipelines and the loop pipelines of the secondary nitrogen cooling module 700 and the tertiary helium cooling module 800. The gaseous refrigerant in the secondary nitrogen cooling module 700 and the tertiary helium cooling module 800 in the present invention is cooled by a fan. A pressure sensor, a differential pressure sensor, a safety valve and a bypass valve are externally connected to the pipeline where the fan is located to monitor the working state of the fan. The secondary nitrogen cooling module 700 and the tertiary helium cooling module 800 are also connected to an external vacuum pump station to ensure the vacuum state inside the module. The secondary nitrogen cooling module 700 in the present invention further includes a nitrogen pre-cooling container 701, which is sleeved on a portion of the current lead 202 and is hollow inside. After the nitrogen refrigerant in the secondary nitrogen cooling module 700 is output, it first passes through the nitrogen pre-cooling container 701 to pre-cool the current lead 202, and then flows into the main vacuum cryostat 500 through a pipeline to assist in cooling the magnet 100, thereby fully utilizing the cooling capacity.

[0027] Preferably, it further includes a protection pipeline 900, which includes: a ventilation pipe 901; One end of the vent pipe 901 is located outside, and the other end passes through the main vacuum cryostat 500, the vacuum cryostat 400 and the heat preservation container 300 in sequence and communicates with the interior of the heat preservation container 300; a protection component is installed on the vent pipe 901; Specifically, the protection component includes a heat anchor 902, an insulation device 903, a manual purge valve 904 and a safety valve, and the heat anchor 902, the insulation device 903, the manual purge valve 904 and the safety valve 905 are all arranged on the ventilation pipe 901. The heat anchor 902 is located on the outer shell of the vacuum cryostat 400 and is used to eliminate the heat brought into the measurement line entering the sample from room temperature. The insulation device 903 is located in the main vacuum cryostat 500 and is used for heat insulation to avoid waste of cold.

[0028] Preferably, it also includes a vacuum system 1000, which is used to evacuate the main vacuum cryostat 500, the vacuum cryostat 400 and the insulation container 300; Specifically, the vacuum system includes three vacuum turbo pumps, which are respectively connected to the heat preservation container 300, the vacuum cryostat 400 and the main vacuum cryostat 500 to ensure the internal vacuum.

[0029] Preferably, it further comprises a connecting sealed container 1100, one end of the connecting sealed container 1100 passes through the main vacuum cryostat 500, the vacuum cryostat 400 and the insulation container 300 in sequence and communicates with the interior of the insulation container 300, and the other end is located outside the main vacuum cryostat 500, and the helium cooling medium in the insulation container 300 flows back to the three-stage helium cooling module 800 through the connecting sealed container 1100; Specifically, after cooling the magnet 100, the cooling medium output by the three-stage helium cooling module 800 still has considerable cold capacity. Although it is not enough to continue to cool the magnet 100, it is sufficient for further pre-cooling the current lead 202. Therefore, the technical solution of the present invention not only fully utilizes the cold capacity of the nitrogen cooling medium, but also fully utilizes the cold capacity of the helium cooling medium.

[0030] Preferably, the current lead 202 passes through the sealed container 1100 and is connected to the magnet 100. That is, the current lead 202 is pre-cooled twice, which effectively reduces the heat after entering the heat preservation container 300, reduces the energy consumption of the refrigeration module, and fully utilizes the cooling capacity.

[0031] Preferably, the heat preservation container 300, the vacuum cryostat 400 and the main vacuum cryostat 500 are all equipped with a first temperature sensor 1200; Specifically, it is convenient to monitor the temperatures in the heat preservation container 300 , the vacuum cryostat 400 and the main vacuum cryostat 500 in real time.

[0032] Preferably, a layer of radiation cooling material is coated on the inner wall of the heat preservation container 300; Specifically, the radiation cooling material can effectively absorb radiation heat, which can assist in heat dissipation on the one hand, and reduce the energy consumption of the secondary nitrogen cooling module 700 and the tertiary helium cooling module 800 in the present invention on the other hand.

[0033] The main purpose of the present invention is to reduce the temperature of the magnet 100, so that the magnet 100 becomes a superconducting state, effectively shorten the helium cooling time, and effectively reduce the refrigeration capacity of the three-stage helium cooling module 800 (under the same cooling capacity, the lower the temperature of the refrigerator, the more energy is consumed). The first-level water cooling module 600 of the present invention effectively controls the temperature of the power copper bar 201 to keep its temperature constant, and prevents the ambient temperature fluctuation from affecting the cooling capacity demand of the second-level nitrogen cooling module 700. The second-level nitrogen cooling module 700 can greatly reduce the temperature of the current lead 202 and the main vacuum cryostat 500, which can effectively reduce the cooling capacity demand of the three-stage helium cooling module 800. Therefore, the present invention controls the temperature step by step, and the system runs stably. The use of nitrogen refrigerators and helium refrigerators can make the refrigerant recycled, and the equipment can be continuously cooled after one filling.

[0034] At the same time, the present invention also adopts a multi-stage helium cooling module and a multi-stage nitrogen cooling module. By adjusting the refrigeration energy level, the start and stop of the individual refrigerators are controlled, and the temperature inside the helium cooling and nitrogen cooling boxes is accurately controlled, and the energy-saving effect of the system is significant.

[0035] In addition, the refrigerant in the technical solution of the present invention can also use liquid refrigerant, the secondary nitrogen cooling module 700 is soaked in liquid nitrogen instead; the tertiary helium cooling module 800 is soaked in liquid helium instead; the tertiary helium cooling module 800 and the secondary nitrogen cooling module 700 include various types of refrigerators, such as GM refrigerators, Stirling refrigerators, pulse tube refrigerators, dilution refrigerators, etc. The refrigerant nitrogen can also be replaced with argon. The three-stage system of the present invention can also achieve the required refrigeration effect by removing the primary water cooling module 600, but the cooling capacity demand of the secondary nitrogen cooling module 700 will change with the ambient temperature.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0040] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A three-stage refrigeration system based on superconducting magnets, characterized in that: include: Power Supply Assembly (200); A heat-insulating container (300); a magnet (100) is placed inside the heat-insulating container (300); A vacuum low-temperature thermostat (400), wherein the heat-insulating container (300) is arranged inside the vacuum low-temperature thermostat (400); A main vacuum cryostat (500); the vacuum cryostat (400) is arranged inside the main vacuum cryostat (500), and one end of the power supply assembly (200) passes through the main vacuum cryostat (500), the vacuum cryostat (400) and the heat preservation container (300) in sequence to be connected to the magnet (100); A primary water cooling module (600); the water cooling module (600) is connected to one side of the power supply assembly (200); A secondary nitrogen cooling module (700); the secondary nitrogen cooling module (700) is in communication with the interior of the main vacuum cryostat (500); A three-stage helium cooling module (800); the three-stage helium cooling module (800) is in communication with the interior of the heat preservation container (300).

2. A three-stage refrigeration system based on superconducting magnets according to claim 1, characterized in that: The power supply assembly (200) comprises: a power supply copper bar (201) and a current lead (202); one side of the power supply copper bar (201) is in contact with the primary water cooling module (600), one end of the current lead (202) is connected to the power supply copper bar (201), and the other end passes through the main vacuum cryostat (500), the vacuum cryostat (400) and the heat preservation container (300) in sequence to be connected to the magnet (100).

3. A three-stage refrigeration system based on superconducting magnets according to claim 2, characterized in that: The primary water cooling module (600) comprises: a constant temperature water tank (601) and a water pump (602); the constant temperature water tank (601) is in communication with a pipeline, a water pump (602) is provided on the pipeline, and a portion of the pipeline is in contact with a power copper busbar (201).

4. A three-stage refrigeration system based on superconducting magnets according to claim 1, characterized in that: The media used in the secondary nitrogen cooling module (700) and the tertiary helium cooling module (800) are both in gaseous state.

5. A three-stage refrigeration system based on superconducting magnets according to claim 1, characterized in that: Also included is a protection pipeline (900), the protection pipeline comprising: a ventilation pipe (901); One end of the vent pipe (901) is located outside, and the other end passes through the main vacuum cryostat (500), the vacuum cryostat (400) and the thermal insulation container (300) in sequence and is connected to the interior of the thermal insulation container (300); a protective component is installed on the vent pipe (901).

6. A three-stage refrigeration system based on superconducting magnets according to claim 1, characterized in that: It also includes a vacuum system (1000), wherein the vacuum system (1000) is used to evacuate the main vacuum cryostat (500), the vacuum cryostat (400) and the thermal insulation container (300).

7. A three-stage refrigeration system based on superconducting magnets according to claim 2, characterized in that: It also comprises a connecting sealed container (1100), one end of the connecting sealed container (1100) sequentially passes through the main vacuum cryostat (500), the vacuum cryostat (400) and the heat preservation container (300) and is connected to the interior of the heat preservation container (300), and the other end is located outside the main vacuum cryostat (500), and the helium cooling medium in the heat preservation container (300) flows back to the three-stage helium cooling module (800) through the connecting sealed container (1100).

8. A three-stage refrigeration system based on superconducting magnets according to claim 7, characterized in that: The current lead (202) passes through the sealed container (1100) and is connected to the magnet (100).

9. A three-stage refrigeration system based on superconducting magnets according to claim 1, characterized in that: The heat-insulating container (300), the vacuum cryostat (400) and the main vacuum cryostat (500) are all equipped with a first temperature sensor (1200).

10. A three-stage refrigeration system based on superconducting magnets according to claim 1, characterized in that: The inner wall of the heat-insulating container (300) is coated with a layer of radiation cooling material.

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