A high-field superconducting magnet low-temperature vertical testing system

Abstract

The present invention discloses a high-field superconducting magnet low-temperature vertical testing system, characterized by comprising a vertical testing dewar equipped with a pressure sensor, a liquid level gauge, a safety valve for rapid pressure relief, and a bursting disc for top blasting; a return gas vaporizer connected to the vertical testing dewar via a low-temperature pipeline at one end and to a helium recovery bag via a first normal-temperature pipeline at the other end; a safety relief valve provided on the first normal-temperature pipeline; a second normal-temperature pipeline, a current lead return gas pipeline, connected at one end to the current lead terminal outlet and at the other end to the return gas vaporizer outlet; a current lead flow controller provided on the second normal-temperature pipeline for controlling the flow of cold helium used to cool the current lead, ensuring that the current lead temperature reaches the operating temperature range; and helium from the first and second normal-temperature pipelines is returned to the helium recovery bag; and a liquid injection port, an emptying port, and a heater provided on the vertical testing dewar. The present invention has the characteristics of simple operation and high safety.

Description

Technical Field

[0001] The present invention relates to the field of cryogenic engineering, and in particular to a high-field superconducting magnet cryogenic vertical testing system. Background Art

[0002] Superconductors exhibit zero resistance and complete diamagnetism below their critical temperature and magnetic field. To test their performance, the temperature must be lowered below this critical temperature. During testing, the superconducting magnet under test is immersed in liquid helium. Because of the liquid helium cryogenic system involved, factors such as the amount of liquid helium and pressure stability in the vertical test dewar are particularly important. Static heat leakage from the vertical test system, heat leakage from the current leads, and quenching during magnet power-up testing all deplete the liquid helium in the dewar, necessitating a steady replenishment of liquid helium to ensure continuous testing.

[0003] A quench during power-up testing of a high-field superconducting magnet consumes liquid helium in the vertical test dewar. When the helium level drops below the required level, cryogenic vertical testing cannot proceed and requires helium replenishment. Traditionally, this was done by moving the dewar. However, the interval between refills caused the temperature of the helium infusion line to rise, leading to helium loss during refilling. Furthermore, the refilling process took too long, reducing testing efficiency.

[0004] Previous vertical testing systems had high requirements for technical personnel, so it is necessary to provide a high-field superconducting magnet low-temperature vertical testing system that is simple to operate, safe and reliable. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to propose a uniquely designed high-field superconducting magnet low-temperature vertical testing system to solve the problems introduced in the above background technology.

[0006] The technical solution of the present invention is:

[0007] A high-field superconducting magnet low-temperature vertical testing system, characterized by comprising:

[0008] Vertical test dewar 001 is used to store liquid helium for vertical testing of high-field superconducting magnets, and a radiation shield 002 is set above the liquid helium surface. The radiation shield 002 is used to reduce heat transfer between the liquid helium and the top flange of the vertical test dewar 001;

[0009] The vertical test dewar 001 is provided with a pressure sensor 003 for monitoring the internal pressure of the vertical test dewar 001 and a liquid level gauge 014 for monitoring the internal liquid level of the vertical test dewar 001;

[0010] The vertical test dewar 001 is provided with a safety valve 004, which is used to initiate a jump when the pressure in the vertical test dewar 001 reaches a jump pressure threshold;

[0011] The vertical test dewar 001 is provided with a bursting disc 006, which is used to blast the top of the vertical test dewar 001 when the pressure inside the vertical test dewar 001 reaches a set bursting pressure threshold;

[0012] The vertical test dewar 001 is provided with a return gas vaporizer 007, one end of which is connected to the vertical test dewar 001 via a low-temperature pipeline, and the other end is connected to the helium recovery bag 010 via a first normal-temperature pipeline, for recovering the low-temperature helium in the vertical test dewar 001 and heating it to room temperature before inputting it into the helium recovery bag 010; the first normal-temperature pipeline includes two parallel branches, the first branch is provided with a safety relief valve 009 for rapid pressure relief; the second branch is provided with a pressure control valve 008 for controlling the liquid helium pressure in the vertical test dewar 001;

[0013] The second normal temperature pipeline is a current lead return gas pipeline, one end of which is connected to the current lead terminal outlet of the high-field superconducting magnet, and the other end is connected to the return gas vaporizer outlet. The second normal temperature pipeline is provided with a current lead flow controller 013, which is used to control the flow of cold helium for cooling the current lead so that the current lead temperature reaches the working temperature zone. The helium of the second normal temperature pipeline merges with the helium of the first normal temperature pipeline at the return gas vaporizer 007 outlet and returns to the helium recovery airbag 010; the vertical test dewar 001 is provided with a liquid injection port 005 for injecting liquid nitrogen or liquid helium into the vertical test dewar 001;

[0014] The vertical test dewar 001 is provided with an exhaust port 011 and a heater 015 for exhausting nitrogen or connecting to room temperature nitrogen through the exhaust port 011 to discharge liquid nitrogen in the reverse direction from the liquid injection port 005.

[0015] Furthermore, the top flange of the vertical test dewar 001 is used to suspend the high-field superconducting magnet to be tested so that it is immersed in liquid helium.

[0016] Furthermore, the take-off pressure threshold is 1.5 bara; the bursting pressure threshold is 2 bara; and when the pressure reaches 1.3 bar, the safety relief valve 009 is fully opened.

[0017] Furthermore, the pressure control range of the pressure control valve 008 is 1 bar-1.3 bara.

[0018] Furthermore, the radiation protection screen 002 includes 7 layers of copper screens distributed vertically.

[0019] Furthermore, when the safety relief valve 009 is opened, the liquid injection port 005 injects liquid helium into the vertical test dewar 001, and the safety relief valve 009 is closed after the liquid injection stops.

[0020] The high-field superconducting magnet low-temperature vertical testing system of the present invention includes a vertical testing dewar 001, a radiation shield 002 inside the dewar, a pressure sensor 003, a safety valve 004, a liquid injection port 005, a bursting disc 006, a return gas vaporizer 007, a pressure control valve 008, a safety relief valve 009, a helium recovery airbag 010, an exhaust port 011, a current lead flow controller 013, a valve 012, a liquid level meter 014, a liquid helium heater 015 inside the dewar, etc. The opening of the valve 012 is automatically controlled according to the flow rate set by the current lead flow controller 13.

[0021] In a preferred embodiment of the present invention, the pressure 003 in the vertical test dewar is controlled by a pressure control valve 008. The pressure range can be precisely controlled to be 1 bara-1.3 bara according to the test requirements. This pressure is the saturated vapor pressure of liquid helium. The lower the pressure, the lower the temperature, which is beneficial for magnet testing. However, if the pressure is too low, the flow rate of cold helium cooling the current lead will be reduced, thereby losing the cooling effect and increasing the temperature. Therefore, it is necessary to precisely control the liquid helium pressure in the dewar through the pressure control valve 008.

[0022] In a preferred embodiment of the present invention, the cold helium return gas is heated to room temperature through an external vaporizer 007 and returned to the helium recovery bag 010. The vaporizers are connected in parallel to reduce pressure loss, which is beneficial for the discharge of the vertical test dewar when the pressure rises under abnormal conditions.

[0023] In a preferred embodiment of the present invention, a safety relief valve 009 is provided with a set pressure of 1.3 bara. When pressure exceeds this set pressure or the magnet quench interlock is triggered, the safety relief valve 009 opens. The valve has a large diameter for rapid pressure relief and also has a manual function, allowing for manual opening during system commissioning.

[0024] In a preferred embodiment of the present invention, a mechanical safety valve 004 and a bursting disc 006 are provided to protect the vertical test dewar in extreme situations.

[0025] In a preferred embodiment of the present invention, a superconducting liquid level gauge 014 is installed in the vertical test dewar to observe the height of the liquid helium level inside the vertical test dewar. When the liquid level reaches a certain height and exceeds the magnet suspension height, power-on testing can be performed.

[0026] In a preferred embodiment of the present invention, the liquid helium storage dewar of the liquid helium refrigerator is connected through the liquid injection port 005 to supply liquid to the vertical test dewar. During testing, liquid injection is stopped and the liquid injection valve is kept at a small opening to prevent the temperature of the infusion tube from rising. When the liquid helium level drops and liquid helium needs to be replenished, the liquid injection valve is opened wider to replenish the liquid in the vertical test dewar to the required level.

[0027] In a preferred embodiment of the present invention, a layer of liquid nitrogen cold shield is arranged in the vacuum interlayer outside the vertical test dewar. Liquid nitrogen is introduced before the vertical test dewar is cooled, so that the liquid nitrogen cooling is maintained in the liquid nitrogen temperature range to reduce the heat leakage of liquid helium inside the vertical test dewar to room temperature.

[0028] In a preferred embodiment of the present invention, since the high-field superconducting magnet has a large cold mass, simply cooling it with liquid helium consumes a lot of liquid helium. Instead, the magnet can be cooled from room temperature to a temperature close to the liquid nitrogen temperature range by first using liquid nitrogen, and then introducing high-pressure room-temperature nitrogen gas after the temperature drops to the liquid nitrogen temperature range and accumulates liquid. The liquid nitrogen is discharged from a liquid infusion tube extending into the bottom of the vertical test dewar until the temperature sensor at the bottom rises to above the saturated liquid nitrogen temperature range, thereby completing the cooling of the magnet from room temperature to a temperature range close to the liquid nitrogen temperature range.

[0029] In a preferred embodiment of the present invention, temperature sensors are provided on a hanger near the bottom of the vertical test dewar, and on the superconducting section and the room temperature end of the current lead.

[0030] Compared with the existing technology, the high-field superconducting magnet low-temperature vertical testing system provided by the present invention has the following advantages:

[0031] First, a pressure control valve 008 is set up to control the pressure of liquid helium in the vertical test dewar, achieving precise pressure control with high pressure control accuracy;

[0032] Second, a large-diameter safety relief valve 009 is provided to relieve pressure in the event of a rapid pressure increase or a quench during magnet testing, thereby ensuring operational safety.

[0033] Third, a return gas vaporizer 007 is installed to heat the cold helium discharged from the vertical test dewar to room temperature to prevent ice and frost from forming along the main return gas pipeline;

[0034] Fourth, the return gas is connected to the helium recovery device and recycled after purification through the purification system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the high-field superconducting magnet low-temperature vertical testing system. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the technical solution of the present invention, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings. Obviously, the embodiments in the following drawings are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0037] refer to Figure 1The first embodiment of the present invention provides a high-field superconducting magnet cryogenic vertical testing system 000, comprising a vertical testing dewar 001, with a dewar internal radiation shield 002 suspended at its top, a liquid level gauge 014 suspended via a level gauge fixture, and a liquid helium heater 015 placed at its bottom. The top of the vertical testing dewar 001 has an end cap flange with holes for mounting accessories such as a pressure sensor 003, a safety valve 004, a liquid injection port 005, a bursting disc 006, and an exhaust port 011. The main return gas line, or cryogenic return gas, enters a helium recovery bag 010 through a return gas vaporizer 007 and parallel pressure control valves 008 and safety relief valves 009. Helium return gas from the cooling current lead enters the helium recovery bag 010 through a current lead flow controller 013. In this embodiment, the high-field superconducting magnet to be tested is immersed in liquid helium in a temperature range of 4.2K for power-on testing. Liquid helium is added through the liquid injection port 005 and stored in the vertical test dewar 001. The pressure sensor 003 and the liquid level gauge 014 are used to monitor the pressure and liquid level in the vertical test dewar. The pressure control valve 008 controls the pressure in the vertical test dewar according to the pressure setting. When the pressure increases, the valve opening is opened wider, and vice versa.

[0038] In this embodiment, the safety relief valve 009 is set to a pressure of 1.3 bara. When the pressure exceeds this value or the magnet malfunction interlock is triggered, the valve opens for rapid pressure relief. Similar to the pressure control valve, helium flowing through this valve is first heated to room temperature by vaporizer 007 before flowing through the valve and entering the helium recovery bag. Furthermore, the safety valve 004 has a trip pressure of 1.5 bara. After tripping, it releases pressure to prevent the pressure inside the vertical test dewar from continuing to rise. Bursting disc 006 has a burst pressure of 2 bara and, together with the safety relief valve 009, forms a three-level safety interlock. During high-field superconducting magnet testing, if the pressure exceeds 1.3 bara, the safety relief valve 009 remains unable to release pressure even after opening. When the pressure reaches 1.5 bara, the safety valve 004 opens. If the pressure continues to rise to 2 bara, the bursting disc 006 explodes, releasing the helium into the atmosphere to protect the vertical test dewar.

[0039] In this embodiment, during the use of the high-field superconducting magnet low-temperature vertical test system, liquid nitrogen cooling is first performed. At the same time, liquid nitrogen is added through the liquid injection port 005 for pre-cooling. Liquid injection is stopped after the bottom temperature sensor reaches the liquid nitrogen temperature. After sufficient immersion, high-pressure room-temperature nitrogen is used to discharge the liquid nitrogen until the bottom temperature sensor exceeds the liquid nitrogen temperature range, ensuring that the liquid nitrogen is completely discharged. This application uses liquid nitrogen pre-cooling to reduce the consumption of liquid helium.

[0040] In the embodiment, after the liquid nitrogen is completely discharged, the vertical test dewar is replaced with helium using a vacuum pump through the exhaust port 011. After sufficient replacement, the safety relief valve 009 is manually opened to connect the vertical test dewar and the helium recovery airbag 010, and liquid helium is added through the liquid injection port 005 until the liquid helium level reaches the level required for magnet testing.

[0041] In this embodiment, after the liquid injection is stopped, the safety relief valve 009 is closed and adjusted to the automatic interlocking state. The liquid helium pressure in the vertical test dewar is controlled by the pressure control valve 008. At the same time, the current lead flow controller 013 is adjusted to make the current lead temperature reach the working temperature range. At this time, the superconducting magnet to be tested meets the test conditions.

[0042] In this embodiment, a quench occurs during the magnet power-up test. The heat generated consumes liquid helium and causes a pressure increase. Pressure control valve 008 automatically adjusts the pressure. If the pressure continues to rise after fully opening, safety relief valve 009 opens to quickly release the pressure. If excessive liquid helium is consumed and the liquid helium level does not meet the required level for magnet testing, the refill valve can be opened to replenish liquid helium.

[0043] In this embodiment, after the test is complete, the remaining liquid helium is evaporated into helium gas and fed into the helium recovery bag 010. Liquid nitrogen injection from the liquid nitrogen cold shield is stopped, and the liquid helium heater 015 in the dewar is turned on to evaporate the liquid helium. When the temperature at the bottom of the dewar exceeds that of liquid helium, the valve connecting the helium recovery bag is closed, the vent 011 is opened, and room-temperature nitrogen is blown in to accelerate the rewarming of the vertical test dewar.

[0044] The above description is only used to illustrate the technical solution of the present invention and does not limit the invention. Although the above embodiments are described in detail, those skilled in the art can replace, modify and simply change them without departing from the scope of the present technical solution. However, these replacements, modifications and simple changes cannot cause the essence of the corresponding technical solution to deviate from the scope of the present invention.

Claims

1. A high-field superconducting magnet low-temperature vertical testing system, characterized in that: include: A vertical test dewar (001) is used to store liquid helium for vertical testing of a high-field superconducting magnet, and a radiation shield (002) is provided above the liquid helium surface, wherein the radiation shield (002) is used to reduce heat transfer between the liquid helium and a top flange of the vertical test dewar (001); The vertical test dewar (001) is provided with a pressure sensor (003) for monitoring the internal pressure of the vertical test dewar (001) and a liquid level meter (014) for monitoring the internal liquid level of the vertical test dewar (001); The vertical test dewar (001) is provided with a safety valve (004) for taking off when the pressure in the vertical test dewar (001) reaches a take-off pressure threshold; The vertical test dewar (001) is provided with a bursting disc (006) for bursting the top of the vertical test dewar (001) when the pressure in the vertical test dewar (001) reaches a set bursting pressure threshold; The vertical test dewar (001) is provided with a return gas vaporizer (007), one end of which is connected to the vertical test dewar (001) via a low-temperature pipeline, and the other end is connected to a helium recovery airbag (010) via a first normal-temperature pipeline, for recovering the low-temperature helium in the vertical test dewar (001), heating it to room temperature, and then inputting it into the helium recovery airbag (010); the first normal-temperature pipeline includes two parallel branches, the first branch is provided with a safety relief valve (009) for rapid pressure relief; the second branch is provided with a pressure control valve (008) for controlling the pressure of liquid helium in the vertical test dewar (001); The second normal temperature pipeline is a current lead return pipeline, one end of which is connected to the current lead terminal outlet of the high-field superconducting magnet, and the other end is connected to the return gas vaporizer (007) outlet. The second normal temperature pipeline is provided with a current lead flow controller (013), and the current lead flow controller (013) is used to control the flow of cold helium for cooling the current lead so that the current lead temperature reaches the working temperature zone. The helium of the second normal temperature pipeline merges with the helium of the first normal temperature pipeline at the return gas vaporizer (007) outlet and returns to the helium recovery airbag (010); The vertical test dewar (001) is provided with a liquid injection port (005) for injecting liquid nitrogen or liquid helium into the vertical test dewar (001); The vertical test dewar (001) is provided with an exhaust port (011) and a heater (015) for exhausting nitrogen or connecting to nitrogen at room temperature through the exhaust port (011) to discharge liquid nitrogen in the reverse direction from the liquid injection port (005).

2. The high-field superconducting magnet low-temperature vertical testing system according to claim 1, characterized in that: The top flange of the vertical test dewar (001) is used for suspending the high-field superconducting magnet to be tested so as to immerse it in liquid helium.

3. The high-field superconducting magnet low-temperature vertical testing system according to claim 1, characterized in that: The trip pressure threshold is 1.5 bara; the burst pressure threshold is 2 bara; when the pressure reaches 1.3 bar, the safety relief valve (009) is fully opened.

4. The high-field superconducting magnet low-temperature vertical testing system according to claim 3, characterized in that: The pressure control range of the pressure control valve (008) is 1 bar-1.3 bara.

5. The high-field superconducting magnet low-temperature vertical testing system according to claim 1, characterized in that: The radiation protection screen (002) comprises 7 layers of copper screens distributed vertically.

6. The high-field superconducting magnet low-temperature vertical testing system according to claim 1, characterized in that: When the safety relief valve (009) is opened, the liquid injection port (005) injects liquid helium into the vertical test dewar (001), and the safety relief valve (009) is closed after the liquid injection stops.

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