Offline system for superconducting magnet and refrigeration assembly

Abstract

The present application is applied to the technical field of superconducting applications, and discloses an offline system for a superconducting magnet and a refrigeration assembly, comprising a helium gas pipe assembly, a cold head, a self-sealing joint set, a two-position four-way valve set, a compressor, and a power supply that supplies power to the compressor. In the present application, the compressor and the cold head are connected by means of the helium gas pipe assembly, helium gas is used as a medium in contact with a thermal interface, and self-sealing joints are arranged at the connection and disconnection points of helium gas pipelines, so that the problems such as frost formation at the thermal interface can be avoided, greatly reducing the offline-to-reconnection time of the system. In addition, no foreign gas is introduced during the entire offline-to-reconnection process, thereby improving the reliability of the offline system for the superconducting magnet and the refrigeration assembly.

Description

An offline system of a superconducting magnet and a refrigeration assembly

[0001] This application claims priority to the Chinese Patent Application No. 202410456368.2, filed on April 16, 2024, and entitled "An offline system of a superconducting magnet and a refrigeration assembly", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application belongs to the field of superconducting applications, and more particularly relates to an offline system of a superconducting magnet and a refrigeration assembly. BACKGROUND

[0003] The superconducting magnet is a key core component of the maglev train, which mainly provides a strong magnetic field required for traction, suspension and guidance of the maglev train.

[0004] The superconducting magnet needs to carry out related performance test in the principle prototype stage to meet the service requirements of high safety and high reliability. In some tests, the superconducting magnet is required to be disconnected from the refrigeration assembly in the working state, that is, to be tested in the offline state, and after the test is completed, the refrigeration assembly needs to be reconnected and made to work to restore the internal temperature of the superconducting magnet and discharge the heat generated due to the disconnection. The disconnection and reconnection process is generally expected to be lossless and reversible, so as to provide consistent internal temperature conditions of the superconducting magnet for the next disconnection test, which is a direct influencing factor of the performance of the superconducting magnet.

[0005] The existing disconnection device of the superconducting magnet and the refrigeration assembly directly exposes the cold guide interface to the air after disconnection, and needs a long time to deal with the frost problem of the cold guide interface before reconnection, thereby affecting the test efficiency of the superconducting magnet and the temperature of the superconducting coil; and during the reconnection process, impurities will be mixed in, thereby affecting the recovery of the working state of the superconducting magnet after the refrigeration assembly is reconnected; in summary, the reliability of the disconnection device of the superconducting magnet and the refrigeration assembly is low.

[0006] SUMMARY

[0007] Therefore, the present application provides an offline system of a superconducting magnet and a refrigeration assembly to solve the problem of low reliability of the existing disconnection device of the superconducting magnet and the refrigeration assembly.

[0008] To solve the above problems, the present application provides the following solutions:

[0009] An offline system of a superconducting magnet and a refrigeration assembly, comprising: a helium tube group, a cold head, a self-sealing joint group, a two-position four-way valve group, a compressor and a power supply for the compressor; wherein:

[0010] The helium tube group comprises a first helium tube and a second helium tube;

[0011] The gas outlet pipe of the cold head is connected with the gas return pipe of the compressor through a first helium pipe, and the gas inlet pipe of the cold head is connected with the gas outlet pipe of the compressor through a second helium pipe; and the gas outlet pipe of the cold head, the gas inlet pipe of the cold head, the gas return pipe of the compressor and the gas outlet pipe of the compressor are all provided with self-sealing joints for connecting or disconnecting the helium pipes;

[0012] The two-position four-way valve set includes a first two-position four-way valve and a second two-position four-way valve; the first two-position four-way valve is connected in series between the gas outlet pipe of the cold head and the gas inlet pipe of the cold head, and is used for controlling the working state of the cold head to match the offline running condition or the reconnection condition; the second two-position four-way valve is connected in series between the gas return pipe of the compressor and the gas outlet pipe of the compressor, and is used for controlling the working state of the compressor to match the balanced gas pressure condition or the normal condition.

[0013] Optionally, the ball valve set is further included;

[0014] The ball valve set includes a first ball valve and a second ball valve; the first ball valve is arranged at the gas return pipe of the compressor, and is used for shutting off the gas return pipe of the compressor in the maintenance condition; the second ball valve is arranged at the gas outlet pipe of the compressor, and is used for shutting off the gas outlet pipe of the compressor in the maintenance condition.

[0015] Optionally, the pressure gauge set is further included, and is used for displaying the pressure in the helium pipes;

[0016] The pressure gauge set includes a first pressure gauge and a second pressure gauge; the first pressure gauge is connected with the first two-position four-way valve; and the second pressure gauge is connected with the second two-position four-way valve.

[0017] Optionally, the needle valve set is further included, and is used for pressure relief;

[0018] The needle valve set includes a first needle valve and a second needle valve; the first needle valve is connected with the first two-position four-way valve; and the second needle valve is connected with the second two-position four-way valve.

[0019] Optionally, the adjustable pressure relief valve is further included;

[0020] The adjustable pressure relief valve is connected with the first two-position four-way valve, and is used for discharging residual gas in the helium pipes.

[0021] Optionally, in the offline running state, wherein:

[0022] The power supply is in the off state;

[0023] The first helium pipe and the second helium pipe are in the disconnected state;

[0024] The cold head is in the offline running condition by adjusting the first two-position four-way valve; and the compressor is in the balanced gas pressure condition by adjusting the second two-position four-way valve.

[0025] Optionally, the method further includes:

[0026] When the preset take-off point of the adjustable pressure relief valve is reached, the adjustable pressure relief valve starts to relieve pressure and automatically closes after relieving pressure.

[0027] Optionally, in the reconnection state, wherein:

[0028] The power supply is in an open state;

[0029] The first helium pipe and the second helium pipe are in a communication state;

[0030] By adjusting the first two-position four-way valve, the cold head is in a reconnection working condition.

[0031] Optionally, it further comprises a maintenance state;

[0032] The maintenance state comprises a vehicle-mounted side maintenance state, a ground side maintenance state and an adjustable pressure relief valve setting state; the vehicle-mounted side is the side where the cold head is located, and the ground side is the side where the compressor is located.

[0033] Optionally, it comprises:

[0034] In the vehicle-mounted side maintenance state, by adjusting the first two-position four-way valve, the cold head is in an offline running working condition, the first needle valve is opened to empty the helium pipe on the vehicle-mounted side and then closed;

[0035] In the ground side maintenance state, by adjusting the second two-position four-way valve, the compressor is in a balanced gas pressure working condition, and the second needle valve is opened to empty the helium pipe on the ground side and then closed;

[0036] In the adjustable pressure relief valve setting state, by adjusting the first two-position four-way valve, the cold head is in an offline running working condition, the first pressure gauge is observed, the adjustable pressure relief valve is adjusted until the first pressure gauge displays the required pressure reading.

[0037] From the above scheme, it can be known that the offline system of the superconducting magnet and the refrigeration assembly disclosed in the present application comprises a helium pipe group, a cold head, a self-sealing joint group, a two-position four-way valve group, a compressor and a power supply for the compressor. In the present application, the compressor and the cold head are connected through the helium pipe group, helium is used as the medium for contacting the cold interface, and the self-sealing joints are arranged at the connection and disconnection positions of the helium pipe, which can avoid problems such as frosting of the cold interface, greatly shortening the time for system offline and reconnection. Moreover, no impure gas is mixed in the entire offline and reconnection process, improving the reliability of the offline system of the superconducting magnet and the refrigeration assembly. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and the other drawings can be obtained by those skilled in the art without creative effort based on these drawings.

[0039] Fig. 1 is a structural diagram of an offline system of a superconducting magnet and a refrigeration assembly provided by the present application;

[0040] Fig. 2 is an example structural diagram of an offline system of a superconducting magnet and a refrigeration assembly provided by the present application.

[0041] Legend: first helium pipeline 1, second helium pipeline 2, gas outlet pipe of cold head 3, gas inlet pipe of cold head 4, return gas pipe of compressor 5, gas outlet pipe of compressor 6, self-sealing joint 7, first two-position four-way valve 8, second two-position four-way valve 9, first ball valve 10, second ball valve 11, first pressure gauge 12, second pressure gauge 13, first needle valve 14, second needle valve 15, adjustable pressure relief valve 16, power supply 17. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of protection of the present application.

[0043] The term "comprising" and its variants are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Related definitions of other terms will be given in the following description.

[0044] It should be noted that the terms "first", "second", etc. mentioned in the present application are only used to distinguish different devices, modules or units, and are not used to limit the functions performed by these devices, modules or units or the mutual dependency relationship.

[0045] It should be noted that the modification of "one" or "multiple" in the present application is illustrative but not restrictive, and those skilled in the art should understand that unless otherwise explicitly indicated in the context, it should be understood as "one or more".

[0046] A superconducting magnet is an electromagnet made from superconducting wire, capable of conducting current without resistance or magnetic losses at very low temperatures, and produces a strong magnetic field. A superconducting magnet can maintain a superconducting state when the temperature is lower than the critical temperature. The superconducting magnet includes a high-temperature superconducting magnet, which is a device that can form a strong magnetic field after being energized by winding a high-temperature superconducting tape, and is a key core component of a maglev train. It is necessary to carry out related testings in the principle prototype stage, such as vehicle electric suspension testing, traction force testing, and speed curve testing.

[0047] In the scaled-down maglev test, the scaled-down maglev vehicle is the minimum system, and the power supply on the vehicle cannot meet the energy consumption requirements of the low-temperature refrigeration system of the superconducting magnet, and cannot meet the high-power consumption. Therefore, in the known technology, the ground power supply is used to continuously supply power to the superconducting magnet refrigerator. At the same time, the loading capacity of the small test vehicle is limited, and the compressor and water chiller of the low-temperature refrigeration system cannot be loaded. In summary, in the existing test of the superconducting magnet, the vehicle power supply and the load cannot meet the working requirements of the superconducting magnet refrigeration assembly.

[0048] In the test of the superconducting magnet, from the power supply and load angles, the superconducting magnet is required to be able to operate independently of the low-temperature refrigeration assembly, and after the test is completed, the low-temperature refrigeration assembly can be reconnected and the state before being disconnected can be restored.

[0049] In actual testing, after the superconducting magnet is disconnected from the low-temperature refrigeration assembly, the ambient temperature of the internal superconducting material will gradually increase, and when it reaches the superconducting material's critical temperature, the superconducting magnet will demagnetize, which cannot guarantee the test requirements of the test system. At the same time, the maximum duration of the superconducting magnet needs to be considered. In actual testing, the existing superconducting magnet test device has problems such as frosting at the cooling interface under the off-line operation condition, so defrosting treatment and other operations need to be performed before reconnection, which will occupy a certain amount of time. The longer the time consumed in the process of disconnecting and reconnecting the refrigerator, the shorter the available test time, which cannot guarantee the effectiveness and efficiency of the superconducting magnet test. In the test process of the existing superconducting magnet and refrigeration assembly off-line and reconnection test, impurities will be mixed in the reconnection process, which will affect the test effect of the superconducting magnet. In summary, the reliability of the existing superconducting magnet and refrigeration assembly off-line device is low.

[0050] To solve the above problems, the application provides a superconducting magnet and refrigeration assembly off-line system.

[0051] Referring to FIG. 1, the composition structure diagram of the superconducting magnet and refrigeration assembly off-line system provided by the application.

[0052] The off-line system of the superconducting magnet and the refrigeration assembly includes a helium pipe group, a cold head, a self-sealing joint group, a two-position four-way valve group, a compressor, and a power supply 17 for powering the compressor. The power supply 17 can be arranged in the compressor or in a power distribution cabinet.

[0053] For this scheme, the inventors propose to divide into the vehicle-mounted side and the ground side, and to leave the cold head and part of the helium pipe on the vehicle, and to place the helium compressor, the water chiller, and the remaining helium pipe on the ground. By adding an assembly in the helium pipe, the superconducting magnet is quickly and losslessly separated from the low-temperature refrigeration system (which can also be referred to as a refrigerator or refrigeration assembly). The division into the vehicle-mounted side and the ground side can ensure that the power supply meets the energy consumption requirements of the low-temperature refrigeration system of the superconducting magnet and meets the demand for high-power consumption. It should be noted that the low-temperature refrigeration system is mainly equipment for providing a low-temperature environment for the superconducting magnet.

[0054] As shown in FIG. 1, the helium pipe group includes a first helium pipe 1 and a second helium pipe 2. The gas outlet pipe 3 of the cold head is connected to the gas return pipe 5 of the compressor through the first helium pipe 1, and the gas inlet pipe 4 of the cold head is connected to the gas outlet pipe 6 of the compressor through the second helium pipe 2. It should be noted that the cold head is a component of the refrigeration equipment, and the refrigeration end is a copper block connected to the structure to be cooled. The cold head is connected to the helium pipe group, and the helium in the helium pipe serves as a cooling working medium to achieve constant low-temperature cooling of the superconducting coil. Moreover, the cold head is installed in the superconducting magnet on the vehicle, and the compressor is installed on the ground. It can be understood that the helium pipe group connects the components on the ground and the vehicle.

[0055] Each self-sealing joint 7 in the self-sealing joint group is installed at the gas outlet pipe 3 of the cold head, the gas inlet pipe 4 of the cold head, the gas return pipe 5 of the compressor, and the gas outlet pipe 6 of the compressor. The self-sealing joint is mainly used to connect or disconnect the superconducting magnet. The self-sealing joint 7 will automatically seal after disconnecting the helium pipe group, ensuring that the outside air does not contaminate the high-purity helium in the original pipe, thereby avoiding the mixing of impure gas and affecting the refrigeration efficiency.

[0056] Specifically, referring to FIG. 2, the composition structure example diagram of the off-line system of the superconducting magnet and the refrigeration assembly provided by the present application, the self-sealing joint group is divided into a male head and a female head. The male head can be 7, 19, 21, 23, 25, and 27, and the corresponding female head can be 18, 20, 22, 24, 26, and 28. It can be understood that the self-sealing joints in the self-sealing joint group appear in pairs and can also be interchanged.

[0057] The two-position four-way valve set includes a first two-position four-way valve 8 and a second two-position four-way valve 9. The first two-position four-way valve 8 is located on the vehicle side and is connected in series between the gas outlet pipe 3 of the cold head and the gas inlet pipe 4 of the cold head, and is mainly used to control the working state of the cold head. The working state of the cold head mainly includes an offline running condition and a reconnection condition. The working state of the cold head can be controlled by adjusting the valve position of the first two-position four-way valve 8 to match the offline running condition or the reconnection condition.

[0058] The second two-position four-way valve 9 is connected in series between the gas return pipe 5 of the compressor and the gas outlet pipe 6 of the compressor, and is mainly used to control the working state of the compressor. The working state of the compressor mainly includes a balanced gas pressure condition and a normal condition. The working state of the compressor can be controlled by adjusting the second two-position four-way valve 9 to match the balanced gas pressure condition or the normal condition. It should be noted that the normal condition is a working condition in which refrigeration can be performed. The gas outlet pipe 6 of the compressor provides high-pressure helium gas to the cold head, and the gas return pipe 5 of the compressor sends low-pressure helium gas discharged from the cold head back to the compressor. The helium gas flows back and forth in the helium pipeline during this process as a refrigeration working medium and carries away the heat of the cold end of the cold head.

[0059] For the offline system of the superconducting magnet and the refrigeration assembly, a ball valve set, a pressure gauge set, a needle valve set, and an adjustable pressure relief valve 16 are further included.

[0060] For the ball valve set, only the ground side is provided. The ball valve set includes a first ball valve 10 and a second ball valve 11. The first ball valve 10 is arranged at the gas return pipe 5 of the compressor and is mainly used to shut off the gas return pipe 5 of the compressor. For example, in a maintenance condition, the first ball valve 10 is used to shut off the gas return pipe 5 of the compressor. The second ball valve 11 is arranged at the gas outlet pipe 6 of the compressor and is mainly used to shut off the gas outlet pipe 6 of the compressor. For example, in a maintenance condition, the second ball valve 11 is used to shut off the gas outlet pipe 6 of the compressor.

[0061] For the pressure gauge set, a first pressure gauge 12 and a second pressure gauge 13 are included. The pressure gauge set is mainly used to display the pressure in the helium pipeline. The first pressure gauge 12 is connected to the first two-position four-way valve 8, and the second pressure gauge 13 is connected to the second two-position four-way valve 9. It should be noted that when the working state of the compressor is in the normal condition, the pressure difference inside the compressor gas return pipe 5 and the compressor gas outlet pipe 6 is different. When the working state of the compressor is in the balanced gas pressure condition, the gas does not flow inside the compressor gas return pipe 5 and the compressor gas outlet pipe 6, and the second pressure gauge 13 shows a stable reading.

[0062] For the needle valve set, a first needle valve 14 and a second needle valve 15 are included. The needle valve set is mainly used for pressure relief and is applied in a maintenance condition. The first needle valve 14 is connected to the first two-position four-way valve 8, and the second needle valve 15 is connected to the second two-position four-way valve 9. Specifically, the needle valve can be manually operated for pressure relief.

[0063] For the adjustable pressure relief valve 16, mainly used to discharge the residual gas in the helium pipeline due to the increase of pressure after the temperature rises, the adjustable pressure relief valve 16 is connected with the first two-position four-way valve 8. Specifically, the adjustable pressure relief valve 16 can set the take-off point, for example, the take-off point is set to be 2Bar below the maximum allowable pressure of the helium pipeline.

[0064] In summary, the offline system of the superconducting magnet and the refrigeration assembly disclosed in the present application comprises a helium pipe group, a cold head, a self-sealing joint group, a two-position four-way valve group, a compressor and a power supply for the compressor. In the present application, the compressor and the cold head are connected through the helium pipe group, and helium is used as the medium in contact with the cold interface. The self-sealing joints are arranged at the connection and disconnection of the helium pipeline, which can avoid problems such as frosting of the cold interface, greatly shortening the time of system offline and reconnection. Moreover, no impure gas is mixed in the whole offline and reconnection process, improving the reliability of the offline system of the superconducting magnet and the refrigeration assembly.

[0065] For the above-mentioned offline system of the superconducting magnet and the refrigeration assembly, mainly includes three states: offline running state, reconnection state and maintenance state.

[0066] Adjusting the offline system of the superconducting magnet and the refrigeration assembly to the offline running state includes the following operations:

[0067] 1) Turn off the power supply 17 for the compressor.

[0068] 2) Manually adjust the valve position of the first two-position four-way valve 8 to adjust the cold head to the offline running condition.

[0069] 3) Manually adjust the valve position of the second two-position four-way valve 9 to adjust the compressor to the balanced gas pressure condition, so that the internal pressures of the first helium pipeline 1 and the second helium pipeline 2 are balanced. Then, the second two-position four-way valve 9 will automatically return to the valve position in the normal working condition.

[0070] 4) Disconnect the connection between the self-sealing joints 19, 20 and the self-sealing joints 25, 26, and complete the offline running operation.

[0071] In summary, the state of each component involved in the offline state is as follows: the power supply 17 is in the off state, the first helium pipeline 1 and the second helium pipeline 2 are in the disconnected state, the cold head is in the offline running condition, and the compressor is in the balanced gas pressure condition.

[0072] It should be noted that the residual gas in the helium pipeline will gradually increase in pressure during the warming process. When the preset take-off point of the adjustable pressure relief valve 16 is reached, the internal pressure of the pipeline begins to release, and after the pressure relief is completed, the adjustable pressure relief valve 16 will automatically close. The setting of the adjustable pressure relief valve 16 can avoid damage to the helium pipeline and prolong the service life of the helium pipeline.

[0073] Adjusting the off-line system of the superconducting magnet and the refrigeration assembly to the reconnection state includes the following operations:

[0074] 1) connecting the self-sealing joint 19 and the self-sealing joint 20, and the self-sealing joint 25 and the self-sealing joint 26.

[0075] 2) manually adjusting the first two-position four-way valve 8 to adjust the cold head to the reconnection working condition.

[0076] 3) turning on the power supply 17 to complete the reconnection operation.

[0077] In summary, the state of each component involved in the reconnection state is that the power supply 17 is in an open state, the first helium gas pipeline 1 and the second helium gas pipeline 2 are in a connected state, and the cold head is in a reconnection working condition.

[0078] For the maintenance working condition corresponding to the maintenance state, it mainly includes the vehicle side maintenance state, the ground side maintenance state and the adjustable pressure relief valve setting state.

[0079] The vehicle side maintenance state is mainly the state of the off-line system of the superconducting magnet and the refrigeration assembly when maintaining the components on the side of the cold head. The operation of the off-line system of the superconducting magnet and the refrigeration assembly is as follows:

[0080] 1) adjusting the cold head to the off-line running working condition by operating the first two-position four-way valve 8.

[0081] 2) opening the first needle valve 14 to empty the helium pipeline on the vehicle side and then closing it. When the pressure in the helium pipeline is relatively high, the components cannot be replaced, so the needle valve is used for pressure relief in this step.

[0082] The ground side maintenance state is mainly the state of the off-line system of the superconducting magnet and the refrigeration assembly when maintaining the components on the side of the compressor. The operation of the off-line system of the superconducting magnet and the refrigeration assembly is as follows:

[0083] 1) adjusting the compressor to the balanced gas pressure working condition by operating the second two-position four-way valve 9.

[0084] 2) opening the second needle valve 15 to empty the helium pipeline on the ground side and then closing it.

[0085] In the adjustable pressure relief valve setting state, the first two-position four-way valve 8 is adjusted so that the cold head is in the off-line running working condition, the first pressure gauge 12 is observed, and the adjustable pressure relief valve 16 is adjusted until the first pressure gauge 12 displays the required pressure reading.

[0086] In summary, the off-line running mode of the off-line system of the superconducting magnet and the refrigeration assembly provided by the present application is simple and fast to operate and easy to implement. In actual application, it is measured that the off-line or reconnection process can be completed in 20 seconds, which reserves sufficient time for vehicle testing.

[0087] It should be noted that each of the arrangements described in the specification is an embodiment of the application and that the specification can include a plurality of embodiments. Furthermore, the above description is provided as an overall functional description of the operations, effects and / or configurations of the application, and not as a component- by-component or step-by-step description. Therefore, the sequence of the operations, effects and / or configurations can be different from the described one, and it is only provided for the purpose of explanation and is not intended to limit the scope of the application.

[0088] Finally, it should be noted that the terms such as first, second, third and fourth, etc. are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Also, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0089] The above description is only the preferred embodiment of the application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the application, a number of improvements and refinements can be made, which should be considered as the protection scope of the application.

Claims

1. An offline system of a superconducting magnet and a refrigeration assembly, characterized in that, Comprise: Helium pipe group, cold head, self-sealing joint group, two-position four-way valve group, compressor and power supply for the compressor; wherein: The helium pipe group comprises a first helium pipe and a second helium pipe; The gas outlet pipe of the cold head is connected with the gas return pipe of the compressor through the first helium pipe, and the gas inlet pipe of the cold head is connected with the gas outlet pipe of the compressor through the second helium pipe; and the gas outlet pipe of the cold head, the gas inlet pipe of the cold head, the gas return pipe of the compressor and the gas outlet pipe of the compressor are all provided with self-sealing joints, which are used to realize connection or disconnection of the helium pipe; The two-position four-way valve group comprises a first two-position four-way valve and a second two-position four-way valve, the first two-position four-way valve is connected in series between the gas outlet pipe of the cold head and the gas inlet pipe of the cold head, which is used to control the working state of the cold head to match the offline running condition or the reconnection condition; the second two-position four-way valve is connected in series between the gas return pipe of the compressor and the gas outlet pipe of the compressor, which is used to control the working state of the compressor to match the balanced gas pressure condition or the normal condition.

2. The offline system of a superconducting magnet and a refrigeration assembly of claim 1, characterized in that, Further comprising a ball valve group; The ball valve group comprises a first ball valve and a second ball valve; the first ball valve is arranged at the gas return pipe of the compressor, which is used to shut off the gas return pipe of the compressor in the maintenance condition; the second ball valve is arranged at the gas outlet pipe of the compressor, which is used to shut off the gas outlet pipe of the compressor in the maintenance condition.

3. The offline system of a superconducting magnet and a refrigeration assembly of claim 1, wherein, Further comprising a pressure gauge group, which is used to display the pressure in the helium pipe; The pressure gauge group comprises a first pressure gauge and a second pressure gauge; the first pressure gauge is connected with the first two-position four-way valve; the second pressure gauge is connected with the second two-position four-way valve.

4. The offline system of a superconducting magnet and a cryogenic assembly of claim 3, wherein, Further comprising a needle valve group, which is used to release pressure; The needle valve group comprises a first needle valve and a second needle valve; the first needle valve is connected with the first two-position four-way valve; the second needle valve is connected with the second two-position four-way valve.

5. The offline system of a superconducting magnet and a refrigeration assembly of claim 4, characterized in that, Further comprising an adjustable pressure relief valve; The adjustable pressure relief valve is connected with the first two-position four-way valve, which is used to discharge residual gas in the helium pipe.

6. The offline system of a superconducting magnet and a refrigeration assembly of claim 1, wherein, In the offline running state, wherein: The power supply is in the off state; The first helium pipe and the second helium pipe are in the disconnected state; By adjusting the first two-position four-way valve, the cold head is in the offline running condition; by adjusting the second two-position four-way valve, the compressor is in the balanced gas pressure condition.

7. The offline system of a superconducting magnet and a refrigeration assembly of claim 5, wherein, Further comprising: When the preset take-off point of the adjustable pressure relief valve is reached, the adjustable pressure relief valve starts to release pressure, and automatically closes after completing the pressure release.

8. The offline system of a superconducting magnet and a refrigeration assembly of claim 1, wherein, In the reconnection state, wherein: The power supply is in the on state; The first helium pipe and the second helium pipe are in the connected state; By adjusting the first two-position four-way valve, the cold head is in the reconnection condition.

9. The offline system of a superconducting magnet and a refrigeration assembly of claim 5, wherein, Further comprising a maintenance state; The maintenance state comprises a vehicle side maintenance state, a ground side maintenance state and an adjustable pressure relief valve setting state; the vehicle side is the side where the cold head is located, and the ground side is the side where the compressor is located.

10. The offline system of a superconducting magnet and a refrigeration assembly of claim 9, characterized in that, Comprise: In the vehicle side maintenance state, the cold head is in the offline operation condition by adjusting the first two-position four-way valve, the first needle valve is opened to empty the helium pipeline of the vehicle side and then closed; In the ground side maintenance state, the compressor is in the balanced gas pressure condition by adjusting the second two-position four-way valve, the second needle valve is opened to empty the helium pipeline of the ground side and then closed; In the adjustable pressure relief valve setting state, the cold head is in the offline operation condition by adjusting the first two-position four-way valve, the first pressure gauge is observed, the adjustable pressure relief valve is adjusted until the first pressure gauge displays the required setting pressure.

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