System and method for testing heat insulation performance of liquid helium storage and transportation container

Abstract

The invention relates to the field of heat insulation performance testing of low-temperature cryogenic containers, and provides a system and a method for testing heat insulation performance of a liquid helium storage and transportation container. According to the system, high-purity helium replacement treatment is carried out on a liquid helium storage and transportation container through a gas replacement module; any one of liquid helium direct pre-cooling, liquid nitrogen pre-cooling and liquid helium pre-cooling or helium liquefier pre-cooling can be carried out on the liquid helium inner container through the pre-cooling module; and the performance test module is used for carrying out heat insulation performance tests including interlayer vacuum degree measurement, gas leakage and discharge rate, leakage rate, static evaporation rate and maintenance time on the liquid helium storage and transportation container. According to the invention, gas replacement, pre-cooling filling and multiple heat insulation performance tests of the liquid helium storage and transportation container can be realized through one set of system. According to the invention, various conditions of pre-cooling treatment of the liquid helium storage and transportation container are fully considered, including direct pre-cooling of liquid helium, pre-cooling of liquid nitrogen and then pre-cooling of liquid helium, and pre-cooling treatment by using a helium liquefier, so that the system adapts to different field conditions, and the universality of the test system is improved.

Description

Technical Field

[0001] The present invention relates to the field of thermal insulation performance testing of cryogenic containers, and in particular to a system and method for testing the thermal insulation performance of a liquid helium storage and transportation container. Background Art

[0002] According to the current domestic standards on cryogenic containers, GB / T 18443-2010 "Test Methods for Performance of Vacuum Insulated Cryogenic Equipment", GB / T18442-2019 "Fixed Vacuum Insulated Cryogenic Pressure Vessels", and NB / T 47059-2017 "Refrigerated Liquefied Gas Tank Containers", five insulation performance test indicators are specified, including interlayer vacuum degree, leakage and degassing rate, leakage rate, static evaporation rate, and maintenance time. The above test items require different test equipment, and generally a separate test platform is built for a certain test item. This model results in the need for more test platforms to achieve all test items.

[0003] Moreover, most of the above-mentioned test platforms adopt the method of temporarily building test platforms, which can only test one or several items, and there is no comprehensive test system covering all indicators of thermal insulation performance.

[0004] Therefore, the prior art still has deficiencies and needs to be further improved. Summary of the invention

[0005] The embodiment of the present invention provides a system and method for testing the thermal insulation performance of a liquid helium storage and transportation container, so as to at least solve the problem that in the thermal insulation performance test of the liquid helium storage and transportation container refrigeration system in the prior art, the test items are relatively single and cannot cover all the thermal insulation performance indicators.

[0006] According to one embodiment of the present invention, a system for testing the thermal insulation performance of a liquid helium storage and transportation container is provided, comprising the following steps:

[0007] Nitrogen storage tank, used to store nitrogen;

[0008] Helium storage tank, used to store helium;

[0009] A liquid helium storage and transportation container is provided with a liquid helium inner container and a liquid nitrogen container, the liquid helium inner container is connected to a helium storage tank, and the liquid nitrogen container is connected to a nitrogen storage tank;

[0010] The replacement gas module is connected to the liquid helium inner container and the helium storage tank respectively, and is connected to the liquid nitrogen inner container and the nitrogen storage tank respectively, and is used to replace the liquid helium inner container and the liquid nitrogen container of the liquid helium storage and transportation container with high-purity gas;

[0011] A precooling module is respectively connected to the liquid helium inner container, the liquid nitrogen storage tank and the liquid helium dewar or the helium liquefier, and is used for precooling the liquid helium inner container, wherein the precooling treatment includes any one of direct liquid helium precooling, liquid nitrogen precooling followed by liquid helium precooling, and precooling using a helium liquefier;

[0012] The performance test module is connected to the liquid helium storage and transportation container and is used to perform thermal insulation performance test on the liquid helium storage and transportation container. The items of the thermal insulation performance test include interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time.

[0013] Preferably, the replacement gas module comprises:

[0014] Detection module, used to detect the purity of helium in liquid helium storage and transportation containers;

[0015] One end of the vacuum pump group is connected to one end of the eighth pipeline, the other end of the eighth pipeline and the tenth pipeline are connected to the liquid helium storage and transportation container through the eleventh pipeline and the tenth pipeline, and the other end of the vacuum pump group is connected to the atmosphere; the liquid helium container and the liquid nitrogen container are evacuated by the vacuum pump group, the liquid helium container is replaced with high-purity helium through the helium storage tank, and the liquid nitrogen container is replaced with high-purity nitrogen through the nitrogen storage tank.

[0016] Preferably, the precooling module comprises:

[0017] The liquid helium dewar is connected to the helium storage tank through the fourth pipeline, and is connected to the liquid helium inner container through the fifth pipeline. The gas pressure of the liquid helium dewar is greater than the gas pressure of the liquid helium inner container. The helium storage tank transports helium to the liquid helium dewar through the fourth pipeline, and the liquid helium dewar transports liquid helium to the liquid helium inner container through the fifth pipeline, so as to realize the liquid helium pre-cooling treatment of the liquid helium inner container.

[0018] The liquid nitrogen storage tank is connected to the liquid helium inner container through a twelfth pipeline to transport liquid nitrogen to the liquid helium inner container;

[0019] The helium liquefier has one end that delivers low-temperature cold helium or liquid helium to the liquid helium inner container through the seventh pipeline, and the other end that is connected to the liquid helium inner container through the sixth pipeline; the helium liquefier, the seventh pipeline, the liquid helium inner container, and the sixth pipeline form a circulation loop.

[0020] Preferably, the performance testing module includes:

[0021] A full-range vacuum gauge is connected to the fourteenth pipeline, one end of the fourteenth pipeline is connected to the eighth pipeline, and the other end of the fourteenth pipeline is connected to the vacuum interlayer of the liquid helium storage and transportation container; the full-range vacuum gauge is used to detect the vacuum degree of the interlayer of the liquid helium storage and transportation container;

[0022] A helium mass spectrometer leak detector, connected to the eighth pipeline and the fourteenth pipeline through the first pipeline, and used for detecting the helium leakage rate inside the liquid helium container and outside the liquid helium storage and transportation container;

[0023] The leakage and degassing rate module is connected to the full-scale vacuum gauge, and the leakage and degassing rate is calculated by obtaining the interlayer vacuum degree detected by the full-scale vacuum gauge;

[0024] A helium mass flowmeter is arranged on the ninth pipeline and connected in series with the rewarming heater on the ninth pipeline; the ninth pipeline is connected through the liquid helium inner container of the eleventh pipeline; the rewarming heater is used to heat the helium, and the helium mass flowmeter is used to detect the evaporation amount of the helium;

[0025] The timer is connected to the liquid helium storage and transportation container and is used to record the maintenance time of the stored liquid helium in the liquid helium container.

[0026] Preferably, the replacement gas module further comprises:

[0027] The liquid nitrogen cold trap is arranged on the eighth pipeline, located at the end of the vacuum pump group close to the liquid helium storage and transportation container, and is used to improve the efficiency of vacuuming.

[0028] Preferably, the liquid helium storage and transportation container insulation performance testing system also includes:

[0029] A helium recovery and purification system is connected to a side of the helium mass flow meter away from the retemperature heater, and is used to purify the helium heated by the retemperature heater into high-purity helium;

[0030] The high-pressure helium cylinder is connected to the side of the helium recovery and purification system away from the helium mass flow meter and is used to store the helium processed by the helium recovery and purification system.

[0031] A method for testing the thermal insulation performance of a liquid helium storage and transportation container, comprising the above-mentioned liquid helium storage and transportation container thermal insulation performance testing system, the thermal insulation performance testing method comprising the following steps:

[0032] The liquid helium container is replaced with high-purity helium, and the liquid nitrogen container is replaced with nitrogen;

[0033] Precooling the liquid helium container, including direct precooling of liquid helium, precooling of liquid nitrogen first and then liquid helium, and precooling using a helium liquefier;

[0034] After precooling is completed, the liquid helium storage and transportation container is subjected to an insulation performance test. The items of the insulation performance test include interlayer vacuum measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time.

[0035] Preferably, the liquid helium container is replaced with high-purity helium, and the liquid nitrogen container is replaced with nitrogen, which specifically includes:

[0036] Detect the purity of helium in liquid helium storage and transportation containers;

[0037] If the liquid helium container contains non-high-purity helium, the liquid helium container is replaced with high-purity helium, and the liquid nitrogen container is replaced with nitrogen.

[0038] Preferably, if the liquid helium inner container contains non-high purity helium, the liquid helium inner container is replaced with high purity helium, and the liquid nitrogen container is replaced with nitrogen, which includes:

[0039] The specific treatment of replacing the liquid helium container with high-purity helium is as follows:

[0040] The liquid helium container is evacuated, which includes using a vacuum pump group to evacuate the vacuum degree of the liquid helium container to a first preset pressure value through the eleventh pipeline to the eighth pipeline;

[0041] Filling the liquid helium container with helium, which includes closing the air intake valve of the vacuum pump group, and the helium storage tank filling the liquid helium container with high-purity helium through the third pipeline to the eleventh pipeline until the pressure of the liquid helium container reaches a second preset pressure value;

[0042] Repeat the above vacuuming and helium filling treatments N times until the high-purity helium replacement treatment meets the preset requirements;

[0043] The specific operation of replacing nitrogen in liquid nitrogen containers is as follows:

[0044] The liquid nitrogen container is subjected to vacuum treatment, which includes using a vacuum pump group to evacuate the vacuum degree of the liquid helium container to a third preset pressure value through the tenth pipeline to the eighth pipeline;

[0045] Filling the liquid nitrogen container with nitrogen; including closing the air intake valve of the vacuum pump group, and the nitrogen storage tank filling the liquid nitrogen container with high-purity nitrogen through the second pipeline to the fourteenth pipeline until the pressure of the liquid helium inner container reaches a fourth preset pressure value;

[0046] Repeat the above vacuum treatment and nitrogen filling treatment N times until the high-purity nitrogen replacement treatment meets the preset requirements.

[0047] Preferably, the precooling treatment includes direct precooling with liquid helium, precooling with liquid nitrogen first and then with liquid helium, and precooling with a helium liquefier, which specifically includes:

[0048] Liquid helium direct precooling specifically includes:

[0049] The helium storage tank delivers helium to the liquid helium dewar through the fourth pipeline, pressurizing the liquid helium dewar so that the pressure inside the liquid helium dewar is slightly greater than the pressure inside the liquid helium container of the liquid helium storage and transportation container, thereby forming a pressure difference to drive the liquid helium to flow;

[0050] The liquid helium dewar delivers liquid helium to the liquid helium inner container through the fifth pipeline;

[0051] Liquid nitrogen precooling followed by liquid helium precooling includes:

[0052] The liquid nitrogen storage tank is charged with liquid nitrogen into the liquid helium inner container through the twelfth pipeline;

[0053] When the temperature of the liquid helium container reaches the preset temperature, use the vacuum pump group to extract the nitrogen in the liquid helium container;

[0054] The helium storage tank delivers helium to the liquid helium dewar through the fourth pipeline, pressurizing the liquid helium dewar so that the pressure inside the liquid helium dewar is slightly greater than the pressure inside the liquid helium container of the liquid helium storage and transportation container, thereby forming a pressure difference to drive the liquid helium to flow;

[0055] The liquid helium dewar delivers liquid helium to the liquid helium inner container through the fifth pipeline;

[0056] Precooling with a helium liquefier includes:

[0057] The helium liquefier produces low-temperature cold helium or liquid helium, and the helium liquefier delivers the low-temperature cold helium or liquid helium to the liquid helium inner container through a seventh pipeline;

[0058] The liquid helium inner container is cooled by heat exchange with cold helium or liquid helium, and the helium in the liquid helium inner container is heated and then returns to the helium liquefier through the sixth pipeline;

[0059] Repeat the steps in Precooling with Helium Liquefier.

[0060] The thermal insulation performance test system and method of the liquid helium storage and transportation container in the embodiment of the present invention can realize the replacement gas, container precooling and multiple thermal insulation performance tests including interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time of the liquid helium storage and transportation container through a set of systems. The present invention fully considers various situations of precooling treatment of liquid helium storage and transportation containers, including direct helium precooling, liquid nitrogen precooling first and then liquid helium precooling, and precooling treatment schemes using a helium liquefier, adapts to different field conditions, and improves the versatility of the test system. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0062] Figure 1 It is a schematic diagram of the thermal insulation performance testing system of the liquid helium storage and transportation container of the present invention;

[0063] Figure 2 The present invention is a flow chart of a method for testing the thermal insulation performance of a liquid helium storage and transportation container. DETAILED DESCRIPTION

[0064] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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 should fall within the scope of protection of the present invention.

[0065] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0066] Example 1

[0067] According to one embodiment of the present invention, a system for testing the thermal insulation performance of a liquid helium storage and transportation container is provided. Figure 1 ,include:

[0068] Nitrogen storage tank 2, used for storing nitrogen;

[0069] A helium storage tank 3, used for storing helium;

[0070] The liquid helium storage and transportation container 14 is provided with a liquid helium inner container 14-1 and a liquid nitrogen container 14-2, the liquid helium inner container 14-1 is connected to the helium storage tank 3, and the liquid nitrogen container 14-2 is connected to the nitrogen storage tank 2;

[0071] The replacement gas module is connected to the liquid helium inner container 14-1 and the helium storage tank 3, and is connected to the liquid nitrogen inner container 14-1 and the nitrogen storage tank 2, respectively, and is used to replace the liquid helium inner container and the liquid nitrogen container of the liquid helium storage and transportation container with high-purity gas;

[0072] A precooling module is connected to the liquid helium inner container 14-1, the liquid nitrogen storage tank 6 and the liquid helium dewar 4 or the helium liquefier 5, respectively, and is used to precool the liquid helium inner container 14-1, wherein the precooling treatment includes any one of direct precooling of liquid helium, precooling of liquid nitrogen first and then precooling of liquid helium, and precooling using a helium liquefier;

[0073] The performance test module is connected to the liquid helium storage and transportation container 14 and is used to perform an insulation performance test on the liquid helium storage and transportation container 14, wherein the items of the insulation performance test include interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time.

[0074] The present invention uses a gas replacement module to replace high-purity helium in a liquid helium storage and transportation container; the precooling module can be used to precool the liquid helium container by any of the following methods: direct precooling of liquid helium, precooling of liquid nitrogen first and then liquid helium, and precooling using a helium liquefier; and the performance testing module is used to test the insulation performance of the liquid helium storage and transportation container, including interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate, and maintenance time. The present invention can achieve gas replacement, precooling and filling, multiple insulation performance tests, and helium recovery processing of liquid helium storage and transportation containers through a set of systems. The present invention fully considers various situations of precooling processing of liquid helium storage and transportation containers, including direct precooling of liquid helium, precooling of liquid nitrogen first and then liquid helium, and precooling processing schemes using a helium liquefier; at the same time, the liquid helium transfer filling and liquefier liquefaction liquid production filling scheme and the corresponding helium recovery processing scheme of the gasification process are considered to adapt to different field conditions and improve the versatility of the test system.

[0075] Specifically, the replacement gas module includes:

[0076] A detection module, used to detect the purity of helium in the liquid helium storage and transportation container 14;

[0077] One end of the vacuum pump group 8 is connected to one end of the eighth pipeline G08, and the other end of the eighth pipeline G08 is connected to the liquid helium storage and transportation container 14 through the eleventh pipeline G11 and the tenth pipeline G10 respectively, and the other end of the vacuum pump group 8 is connected to the atmosphere; the liquid helium container 14-1 and the liquid nitrogen container 14-2 are evacuated by the vacuum pump group 8, and the liquid helium container 14-1 is replaced with high-purity helium through the helium storage tank 3, and the liquid nitrogen container 14-2 is replaced with high-purity nitrogen through the nitrogen storage tank 2.

[0078] Specifically, the precooling module includes:

[0079] The liquid helium Dewar 4 is connected to the helium storage tank 3 through the fourth pipeline G04, and is connected to the liquid helium inner container 14-1 through the fifth pipeline G05. The gas pressure of the liquid helium Dewar 4 is greater than the gas pressure of the liquid helium inner container 14-1. The helium storage tank 3 delivers helium to the liquid helium Dewar 4 through the fourth pipeline G04, and the liquid helium Dewar 4 delivers liquid helium to the liquid helium inner container 14-1 through the fifth pipeline G05, so as to realize the liquid helium pre-cooling treatment of the liquid helium inner container 14-1.

[0080] The liquid nitrogen storage tank 6 is connected to the liquid helium inner container 14 - 1 through the twelfth pipeline G12 to transport liquid nitrogen to the liquid helium inner container 14 - 1 .

[0081] The helium liquefier 5 has one end that delivers low-temperature cold helium or liquid helium to the liquid helium inner container 14-1 through the seventh pipeline G07, and the other end that is connected to the liquid helium inner container 14-1 through the sixth pipeline G06; the helium liquefier 5, the seventh pipeline G07, the liquid helium inner container 14-1, and the sixth pipeline G06 form a circulation loop.

[0082] Specifically, the performance testing module includes:

[0083] The full-scale vacuum gauge 13 is connected to the fourteenth pipeline G14, one end of the fourteenth pipeline G14 is connected to the eighth pipeline G08, and the other end of the fourteenth pipeline G14 is connected to the vacuum interlayer of the liquid helium storage and transportation container 14; the full-scale vacuum gauge 13 is used to detect the vacuum degree of the interlayer of the liquid helium storage and transportation container 14;

[0084] The helium mass spectrometer leak detector 1 is connected to the eighth pipeline G08 and the fourteenth pipeline G14 through the first pipeline G01, and is used to detect the helium leakage rate inside the liquid helium inner container 14-1 and outside the liquid helium storage and transportation container 14;

[0085] The leakage and degassing rate module is connected to the full-scale vacuum gauge 13 and calculates the leakage and degassing rate by obtaining the interlayer vacuum degree detected by the full-scale vacuum gauge 13;

[0086] The helium mass flowmeter 10 is arranged on the ninth pipeline G09 and is connected in series with the reheating heater 9 located on the ninth pipeline G09; the ninth pipeline G09 is connected to the liquid helium inner container 14-1 through the eleventh pipeline G11; the reheating heater 9 is used to heat the helium, and the helium mass flowmeter 10 is used to detect the evaporation amount of the helium;

[0087] The timer is connected to the liquid helium storage and transportation container 14 and is used to record the accumulated time of storing the liquid helium in the liquid helium inner container 14-1.

[0088] Specifically, the replacement gas module also includes:

[0089] The liquid nitrogen cold trap 7 is arranged on the eighth pipeline G08, located at the end of the vacuum pump group 8 close to the liquid helium storage and transportation container 14, and is used to improve the efficiency of vacuuming.

[0090] Specifically, the liquid helium storage and transportation container insulation performance test system also includes:

[0091] A helium recovery and purification system 11 is connected to a side of the helium mass flowmeter 10 away from the reheating heater 9, and is used to purify the helium heated by the reheating heater 9 into high-purity helium;

[0092] The high-pressure helium cylinder 12 is connected to a side of the helium recovery and purification system 11 away from the helium mass flowmeter 10 , and is used to store the helium processed by the helium recovery and purification system 11 .

[0093] Specifically, the thermal insulation performance test system of the liquid helium storage and transportation container of the present invention mainly includes a helium mass spectrometer leak detector 1, a nitrogen bottle / storage tank 2, a helium bottle / storage tank 3, a liquid helium dewar 4, a helium liquefier 5, a liquid nitrogen storage tank 6, a liquid nitrogen cold trap 7, a vacuum pump group 8, a reheating heater 9, a helium mass flowmeter 10, a helium recovery and purification system 11, a high-pressure helium bottle 12, a full-range vacuum gauge 13, a liquid helium storage and transportation container to be tested 14, a standard leak hole 15, a vacuum valve 16, a timing system 17 and necessary valves and several pipelines.

[0094] The existing test system requires different test equipment for the five insulation performance test items of interlayer vacuum degree, leakage and degassing rate, leakage rate, static evaporation rate, and maintenance time. Generally, a test platform is built separately for a certain test item. This mode results in more test platforms required to implement all test items. The present invention is a comprehensive test system that integrates all test items. The common equipment, sensors and pipelines of each test item can be shared to avoid duplication of construction and waste of resources; it avoids being dispersed into multiple platforms, which is convenient for unified operation, management and maintenance.

[0095] Example 2

[0096] According to another embodiment of the present invention, a method for testing the thermal insulation performance of a liquid helium storage and transportation container is provided. The thermal insulation performance testing method is performed by applying the above system. Figure 2 , the method comprises the following steps:

[0097] S100: The liquid helium container 14-1 is replaced with high-purity helium, and the liquid nitrogen container 14-2 is replaced with nitrogen;

[0098] S200: precooling the liquid helium inner container 14-1, the precooling process includes direct precooling of liquid helium, precooling of liquid nitrogen first and then liquid helium, and precooling using a helium liquefier;

[0099] S300: After precooling is completed, the liquid helium storage and transportation container 14 is subjected to an insulation performance test, and the items of the insulation performance test include interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time.

[0100] The thermal insulation performance test system and method of the liquid helium storage and transportation container in the embodiment of the present invention can realize the replacement gas, container precooling and multiple thermal insulation performance tests including interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time of the liquid helium storage and transportation container through a set of systems. The present invention fully considers various situations of precooling treatment of liquid helium storage and transportation containers, including direct helium precooling, liquid nitrogen precooling first and then liquid helium precooling, and precooling treatment schemes using a helium liquefier, adapts to different field conditions, and improves the versatility of the test system.

[0101] Step S100 specifically includes:

[0102] S101: Detecting the purity of helium in the liquid helium storage and transportation container 14;

[0103] S102: If the liquid helium container 14-1 does not contain high-purity helium, the liquid helium container 14-1 is replaced with high-purity helium, and the liquid nitrogen container 14-2 is replaced with nitrogen.

[0104] Specifically, before the liquid helium storage and transportation container 14 begins to perform insulation performance testing, if the liquid helium inner container 14-1 contains non-high-purity helium, the testing module needs to replace the inspected liquid helium storage and transportation container 14 with high-purity helium to prevent other impurity gases from freezing in the inner container 14-1 during the subsequent cooling and filling process of liquid helium. For a liquid helium storage and transportation container 14 with a liquid nitrogen cold shield, the liquid nitrogen container 14-2 should adopt a nitrogen replacement operation.

[0105] Step S102 specifically includes:

[0106] The specific steps of replacing the liquid helium inner container 14-1 with high-purity helium are as follows:

[0107] The liquid helium inner container 14-1 is subjected to vacuum treatment, which includes using the vacuum pump group 8 to evacuate the vacuum degree of the liquid helium inner container 14-1 to a first preset pressure value, such as about 1-2Pa, through the eleventh pipeline G11 to the eighth pipeline G08;

[0108] Filling the liquid helium container 14-1 with helium, which includes closing the air inlet valve of the vacuum pump group 8, and the helium storage tank 3 filling the liquid helium container 14-1 with high-purity helium through the third pipeline G03 to the eleventh pipeline G11 until the pressure of the liquid helium container 14-1 reaches a second preset pressure value, such as a pressure of 1.05-2 bar;

[0109] Repeat the above vacuuming and helium filling treatments N times until the high-purity helium replacement treatment meets the preset requirements.

[0110] The specific operation of replacing nitrogen with liquid nitrogen container 14-2 is as follows:

[0111] The liquid nitrogen container 14-2 is evacuated, which includes using the vacuum pump group 8 to evacuate the vacuum degree of the liquid helium inner container 14-1 to a third preset pressure value, such as about 1-2Pa, through the tenth pipeline G10 to the eighth pipeline G08;

[0112] The liquid nitrogen container 14-2 is charged with nitrogen; this includes closing the air inlet valve of the vacuum pump group 8, and the nitrogen storage tank 2 is charged with high-purity nitrogen into the liquid nitrogen container 14-2 through the second pipeline G02 to the fourteenth pipeline G14 until the pressure of the liquid helium inner container 14-1 reaches a fourth preset pressure value, such as a pressure of 1.05-2 bar;

[0113] Repeat the above vacuum treatment and nitrogen filling treatment N times until the high-purity nitrogen replacement treatment meets the preset requirements.

[0114] Step S200 specifically includes:

[0115] Liquid helium direct precooling specifically includes:

[0116] The helium storage tank 3 delivers helium to the liquid helium dewar 4 through the fourth pipeline G04, pressurizing the liquid helium dewar 4, so that the pressure inside the liquid helium dewar 4 is slightly greater than the pressure of the liquid helium inner container 14-1 of the liquid helium storage and transportation container 14, forming a pressure difference to drive the liquid helium to flow;

[0117] The liquid helium Dewar 4 delivers liquid helium to the liquid helium inner container 14-1 through the fifth pipeline G05;

[0118] Liquid nitrogen precooling followed by liquid helium precooling includes:

[0119] The liquid nitrogen storage tank 6 fills the liquid helium inner container 14-1 with liquid nitrogen through the twelfth pipeline G12;

[0120] When the temperature of the liquid helium inner container 14-1 reaches a first preset temperature, such as 77K, the nitrogen in the liquid helium inner container 14-1 is evacuated using the vacuum pump group 8;

[0121] The helium storage tank 3 delivers helium to the liquid helium dewar 4 through the fourth pipeline G04, pressurizing the liquid helium dewar 4, so that the pressure inside the liquid helium dewar 4 is slightly greater than the pressure of the liquid helium inner container 14-1 of the liquid helium storage and transportation container 14, forming a pressure difference to drive the liquid helium to flow;

[0122] The liquid helium Dewar 4 delivers liquid helium to the liquid helium inner container 14-1 through the fifth pipeline G05;

[0123] Precooling with a helium liquefier includes:

[0124] The helium liquefier 5 generates low-temperature cold helium or liquid helium, and the helium liquefier 5 delivers low-temperature cold helium or liquid helium to the liquid helium inner container 14-1 through the seventh pipeline G07;

[0125] The liquid helium inner container 14-1 is cooled by heat exchange with cold helium or liquid helium, and the helium in the liquid helium inner container 14-1 is heated and then returns to the helium liquefier 5 through the sixth pipeline G06;

[0126] Repeat the steps in Precooling with Helium Liquefier.

[0127] According to different test site conditions, the present invention proposes three precooling methods for liquid helium storage and transportation containers, namely, precooling with helium liquefier 5, precooling with liquid nitrogen first and then with liquid helium, and precooling with liquid helium, which are suitable for different site conditions and improve the versatility of the test system.

[0128] The following is an explanation of the implementation method of the thermal insulation performance test system for liquid helium storage and transportation containers:

[0129] 1. The replacement gas is described in detail below:

[0130] Before the liquid helium storage and transportation container 14 begins the insulation performance test, if the liquid helium container 14-1 does not contain high-purity helium, the detection module needs to replace the liquid helium storage and transportation container 14 with high-purity helium to prevent other impurity gases from freezing in the container 14-1 during the subsequent cooling and filling process of liquid helium. For the liquid helium storage and transportation container 14 with a liquid nitrogen cold shield, the liquid nitrogen container 14-2 should adopt the nitrogen replacement operation.

[0131] Specifically, for the liquid helium inner container 14-1 to replace the high-purity helium, the vacuum pump group 8 is used to evacuate the vacuum degree of the liquid helium inner container 14-1 to a first preset pressure value, such as about 1-2Pa, through the eleventh management G11 to the eighth pipeline G08. A liquid nitrogen cold trap 7 is arranged in front of the vacuum pump group 8 to improve the efficiency of vacuuming. Then the air intake valve of the vacuum pump group 8 is closed, and the helium storage tank 3 is connected to the eleventh pipeline G11 via the third pipeline G03, and the liquid helium inner container 14-1 is filled with high-purity helium to a second preset pressure value, such as a pressure of 1.05-2bar. Repeat the above vacuuming and helium filling operations three times.

[0132] Repeat the above vacuuming and helium filling treatments N times until the high-purity helium replacement treatment meets the preset requirements.

[0133] For the liquid helium storage and transportation container 14 equipped with the liquid nitrogen container 14-2, the nitrogen replacement operation is similar to the above-mentioned high-purity helium replacement operation. Specifically, the nitrogen replacement operation for the liquid nitrogen container 14-2 is as follows:

[0134] The liquid nitrogen container 14-2 is evacuated, which includes using the vacuum pump group 8 to evacuate the vacuum degree of the liquid helium inner container 14-1 to a third preset pressure value, such as about 1-2Pa, through the tenth pipeline G10 to the eighth pipeline G08;

[0135] The liquid nitrogen container 14-2 is charged with nitrogen; this includes closing the air inlet valve of the vacuum pump group 8, and the nitrogen storage tank 2 is charged with high-purity nitrogen into the liquid nitrogen container 14-2 through the second pipeline G02 to the fourteenth pipeline G14 until the pressure of the liquid helium inner container 14-1 reaches a fourth preset pressure value, such as 1.05-2 bar;

[0136] Repeat the above vacuum treatment and nitrogen filling treatment N times until the high-purity nitrogen replacement treatment meets the preset requirements.

[0137] Second, the precooling operation is described in detail below:

[0138] If the liquid helium storage and transportation container 14 is at room temperature, it is necessary to pre-cool the container inside the liquid helium storage and transportation container 14. For a liquid helium storage and transportation container 14 equipped with a liquid nitrogen container 14-2, first fill the liquid nitrogen container 14-2 to a specified liquid level. Then start pre-cooling the liquid helium inner container 14-1. There are three specific solutions:

[0139] Solution 1: Direct precooling of liquid helium:

[0140] The liquid helium dewar 4 transports the liquid helium required for precooling to the liquid helium inner container 14-1 of the liquid helium storage and transportation container 14 through the fifth pipeline G05. When the liquid helium dewar 4 transfers liquid helium to the liquid helium inner container 14-1, the liquid helium dewar 4 takes helium from the helium storage tank 3 through the fourth pipeline G04, pressurizes the liquid helium dewar 4, and makes the pressure inside the liquid helium dewar 4 slightly greater than the pressure of the liquid helium inner container 14-1, forming a pressure difference to drive the liquid helium to flow. In actual operation, the transfer flow rate should be controlled to avoid the temperature of the liquid helium inner container 14-1 dropping too fast, and the thermal stress cannot be released in time to cause structural damage.

[0141] Solution 2: Pre-cool with liquid nitrogen first and then with liquid helium:

[0142] Considering the difficulty in liquefying helium, the high energy consumption, and the preciousness of liquid helium resources, the pre-cooling from room temperature to a preset temperature, such as a temperature range above 77K, uses relatively cheap liquid nitrogen for pre-cooling, which can save the amount of liquid helium. That is, first pre-cool the liquid helium inner container 14-1 to 77K with nitrogen, and then use liquid helium to pre-cool the liquid helium inner container 14-1. Specifically, the liquid nitrogen storage tank 6 fills the liquid helium inner container 14-1 with liquid nitrogen through the twelfth pipeline G12 for pre-cooling. When the temperature reaches 77K, the vacuum pump group 8 is used to exhaust the nitrogen in the liquid helium inner container 14-1, and then the liquid helium inner container 14-1 is pre-cooled with liquid helium. The operation process is the same as the above-mentioned scheme 1, which will not be repeated here.

[0143] Option 3: Precooling with helium liquefier:

[0144] The helium liquefier 5, the seventh pipeline G07, the liquid helium inner container 14-1, and the sixth pipeline G06 form a circulation loop. The low-temperature cold helium or liquid helium produced by the helium liquefier 5 is used to pre-cool the liquid helium inner container 14-1 through the seventh pipeline G07, and the helium after the liquid helium inner container 14-1 absorbs heat and heats up returns to the helium liquefier 5 through the sixth pipeline G06, realizing a refrigeration cycle.

[0145] 3. The following is a detailed description of the thermal insulation performance test:

[0146] After precooling, liquid helium is filled into the liquid helium inner container 14-1. The source of liquid helium is liquid helium transported by the liquid helium dewar 4, or liquid helium liquefied by the helium liquefier 5. Liquid helium is filled to the rated filling volume of the liquid helium storage and transportation container 14, and after a period of rest, for example, after 48 hours of rest, the insulation performance test including interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time is started; wherein:

[0147] Interlayer vacuum degree measurement: Use the vacuum pump group 8 to draw the vacuum degree of the fourteenth pipeline G14 to a level better than the interlayer vacuum degree of the vacuum interlayer 14-3 of the liquid helium storage and transportation container, close the vacuum valve 16, open the vacuum valve of the vacuum interlayer 14-3 of the liquid helium storage and transportation container, and use the full-range vacuum gauge 13 to read the interlayer vacuum degree.

[0148] Leak rate test: The inside of the liquid helium inner container 14-1 and the outside of the liquid helium storage and transportation container 14 are filled with helium, and the helium leak rate is tested using a helium mass spectrometer leak detector 1. Before the test, the minimum detectable leak rate of the leak detection system is confirmed using a standard leak hole 15.

[0149] Leakage and degassing rate: The degassing rate can be calculated by reading the change in the interlayer vacuum measurement values ​​twice at a certain interval. For example, the ratio of the difference between the two interlayer vacuum measurement values ​​to the time period.

[0150] Static evaporation rate: When the evaporation of liquid helium in the liquid helium container 14-1 is stable, the evaporated gas passes through the eleventh pipeline G11 to the ninth pipeline G09, is heated to room temperature by the reheating heater 9, and then enters the helium mass flowmeter 10 for evaporation flow test.

[0151] Maintaining time: When the liquid helium storage and transportation container 14 is a pressure container such as a liquid helium tank, the maintaining time is one of the evaluation indicators of the thermal insulation performance. Close all valves connecting the liquid helium inner container 14-1 to the outside world, and start the timer 17 until the accumulated time of the action of the pressure relief device of the liquid helium inner container 14-1 is reached.

[0152] Fourth, the helium recovery process is described in detail below:

[0153] Helium recovery includes helium recovery during the precooling process of the helium liquefier and helium recovery during the precooling process using liquid helium and after the filling is completed, which is evaporated from the liquid helium container 14-1.

[0154] 1. Precooling process using helium liquefier:

[0155] The cold helium or liquid helium obtained from the refrigerator enters the liquid helium inner container 14-1 to absorb heat and increase its temperature. The heated high-temperature helium returns to the refrigeration cycle in the helium liquefier 5 through the sixth pipeline G06.

[0156] 2. The helium gas evaporated from the liquid helium inner container 14-1 after the precooling process and filling of liquid helium are completed:

[0157] The helium gas converted from liquid helium is discharged through the eleventh pipeline G11 to the ninth pipeline G09, heated to room temperature by the reheating heater 9, and then enters the helium recovery and purification system 11 to be purified into high-purity helium and then stored in the high-pressure helium cylinder 12.

[0158] The present invention provides a liquid helium storage and transportation container insulation performance testing system, which has the ability to realize gas replacement and precooling treatment of the liquid helium storage and transportation container, and to realize interlayer vacuum degree, leakage and degassing rate, leakage rate, static evaporation rate, and performance testing of maintenance time and helium recovery processing.

[0159] The test system of the present invention proposes three liquid helium storage and transportation container precooling methods for different test site conditions, namely, precooling by using a helium liquefier 5, precooling by liquid nitrogen first and then by liquid helium, and precooling by liquid helium; and two helium recovery and processing methods, namely, recovering the helium in a helium bag and then purifying it, and directly returning it to the helium liquefier 5.

[0160] The present invention can realize the operation items involved in all test processes of liquid helium storage and transportation container gas replacement, container precooling, liquid helium filling, multiple insulation performance tests, and helium recovery and treatment. All insulation performance tests can be realized through a set of test systems, and various conditions of liquid helium storage and transportation container pretreatment are fully considered, including multiple precooling schemes and helium recovery and treatment schemes, which are adapted to different field conditions and improve the versatility of the test system.

[0161] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A liquid helium storage and transportation container insulation performance testing system, characterized in that: include: Nitrogen storage tank, used to store nitrogen; Helium storage tank, used to store helium; Liquid helium storage and transportation container, which contains a liquid helium container and a liquid nitrogen container; a replacement gas module, connected to the liquid helium inner container and the helium storage tank, respectively, and connected to the liquid nitrogen inner container and the nitrogen storage tank, respectively, for replacing the liquid helium inner container and the liquid nitrogen container of the liquid helium storage and transportation container with high-purity gas; A precooling module, connected to the liquid helium inner container, the liquid nitrogen storage tank and the liquid helium dewar or the helium liquefier, respectively, for precooling the liquid helium inner container, wherein the precooling treatment includes any one of direct precooling of liquid helium, precooling of liquid nitrogen first and then precooling of liquid helium, and precooling using a helium liquefier; A performance testing module is connected to the liquid helium storage and transportation container and is used to perform an insulation performance test on the liquid helium storage and transportation container, wherein the items of the insulation performance test include interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time.

2. The thermal insulation performance testing system for liquid helium storage and transportation containers according to claim 1, characterized in that: The replacement gas module comprises: A detection module, used to detect the purity of the helium in the liquid helium storage and transportation container; A vacuum pump group, one end of which is connected to one end of the eighth pipeline, the other end of the eighth pipeline is connected to the liquid helium storage and transportation container through the eleventh pipeline and the tenth pipeline respectively, and the other end of the vacuum pump group is connected to the atmosphere; the liquid helium container and the liquid nitrogen container are evacuated by the vacuum pump group respectively, the liquid helium container is replaced with high-purity helium by the helium storage tank, and the liquid nitrogen container is replaced with high-purity nitrogen by the nitrogen storage tank.

3. The thermal insulation performance testing system for liquid helium storage and transportation containers according to claim 2, characterized in that: The precooling module comprises: A liquid helium dewar is connected to the helium storage tank through a fourth pipeline, and is connected to the liquid helium inner container through a fifth pipeline, wherein the gas pressure of the liquid helium dewar is greater than the gas pressure of the liquid helium inner container; the helium storage tank delivers helium to the liquid helium dewar through the fourth pipeline, and the liquid helium dewar delivers liquid helium to the liquid helium inner container through the fifth pipeline, so as to achieve liquid helium precooling treatment of the liquid helium inner container; a liquid nitrogen storage tank connected to the liquid helium inner container via a twelfth pipeline to transport liquid nitrogen to the liquid helium inner container; A helium liquefier, one end of which transports low-temperature cold helium or liquid helium to the liquid helium inner container through the seventh pipeline, and the other end of which is connected to the liquid helium inner container through the sixth pipeline; the helium liquefier, the seventh pipeline, the liquid helium inner container, and the sixth pipeline form a circulation loop.

4. The thermal insulation performance testing system for liquid helium storage and transportation containers according to claim 3, characterized in that: The performance test module includes: A full-range vacuum gauge is connected to the fourteenth pipeline, one end of the fourteenth pipeline is connected to the eighth pipeline, and the other end of the fourteenth pipeline is connected to the vacuum interlayer of the liquid helium storage and transportation container; the full-range vacuum gauge is used to detect the vacuum degree of the interlayer of the liquid helium storage and transportation container; a helium mass spectrometer leak detector, connected to the eighth pipeline and the fourteenth pipeline through the first pipeline, and used for detecting the helium leakage rate inside the liquid helium inner container and outside the liquid helium storage and transportation container; A leakage and degassing rate module is connected to the full-scale vacuum gauge and calculates the leakage and degassing rate by obtaining the vacuum degree of the interlayer detected by the full-scale vacuum gauge; a helium mass flowmeter, arranged on the ninth pipeline and connected in series with the rewarming heater located on the ninth pipeline; the ninth pipeline is connected to the liquid helium inner container through the eleventh pipeline; the rewarming heater is used to heat the helium, and the helium mass flowmeter is used to detect the evaporation amount of the helium; The timer is connected to the liquid helium storage and transportation container and is used to record the maintenance time of the stored liquid helium in the liquid helium inner container.

5. The thermal insulation performance testing system for liquid helium storage and transportation containers according to claim 2, characterized in that: The replacement gas module also includes: The liquid nitrogen cold trap is arranged on the eighth pipeline and is located at one end of the vacuum pump group close to the liquid helium storage and transportation container, so as to improve the efficiency of vacuuming.

6. The thermal insulation performance testing system for liquid helium storage and transportation containers according to claim 4, characterized in that: The liquid helium storage and transportation container insulation performance testing system also includes: A helium recovery and purification system is connected to a side of the helium mass flowmeter away from the retemperature heater, and is used to purify the helium heated by the retemperature heater into high-purity helium; A high-pressure helium cylinder is connected to a side of the helium recovery and purification system away from the helium mass flow meter and is used to store the helium processed by the helium recovery and purification system.

7. A method for testing the thermal insulation performance of a liquid helium storage and transportation container, characterized in that: The liquid helium storage and transportation container thermal insulation performance testing system according to claim 4 or 6 is included, and the thermal insulation performance testing method comprises the following steps: The liquid helium container is replaced with high-purity helium, and the liquid nitrogen container is replaced with nitrogen; Precooling the liquid helium inner container, wherein the precooling treatment includes direct precooling of liquid helium, precooling of liquid nitrogen first and then liquid helium, and precooling using a helium liquefier; After the precooling is completed, the liquid helium storage and transportation container is subjected to an insulation performance test, and the items of the insulation performance test include interlayer vacuum degree measurement, leakage and degassing rate, leakage rate, static evaporation rate and maintenance time.

8. The method for testing the thermal insulation performance of a liquid helium storage and transportation container according to claim 7, characterized in that: The step of replacing the liquid helium container with high-purity helium and the step of replacing the liquid nitrogen container with nitrogen specifically include: Detecting the purity of helium in the liquid helium storage and transportation container; If the liquid helium inner container contains non-high-purity helium, the liquid helium inner container is replaced with high-purity helium, and the liquid nitrogen container is replaced with nitrogen.

9. The method for testing the thermal insulation performance of a liquid helium storage and transportation container according to claim 8, characterized in that: If the liquid helium inner container contains non-high-purity helium, the liquid helium inner container is replaced with high-purity helium, and the liquid nitrogen container is replaced with nitrogen, which includes: The specific steps of replacing the liquid helium inner container with high-purity helium are as follows: The liquid helium inner container is subjected to a vacuum treatment, which includes using the vacuum pump group to pump the vacuum degree of the liquid helium inner container to a first preset pressure value through the eleventh pipeline to the eighth pipeline; Filling the liquid helium inner container with helium; the process includes closing the air inlet valve of the vacuum pump group, and the helium storage tank filling the liquid helium inner container with high-purity helium through the third pipeline to the eleventh pipeline until the pressure of the liquid helium inner container reaches a second preset pressure value; Repeat the above vacuuming and helium filling treatments N times until the high-purity helium replacement treatment meets the preset requirements; The specific operation of replacing nitrogen with the liquid nitrogen container is as follows: The liquid nitrogen container is subjected to a vacuum treatment, which includes using the vacuum pump group to pump the vacuum degree of the liquid helium container to a third preset pressure value through the tenth pipeline to the eighth pipeline; Filling the liquid nitrogen container with nitrogen; including closing the air inlet valve of the vacuum pump group, and the nitrogen storage tank filling the liquid nitrogen container with high-purity nitrogen through the second pipeline to the fourteenth pipeline until the pressure of the liquid helium inner container reaches a fourth preset pressure value; Repeat the above vacuum treatment and nitrogen filling treatment N times until the high-purity nitrogen replacement treatment meets the preset requirements.

10. The method for testing the thermal insulation performance of a liquid helium storage and transportation container according to claim 9, characterized in that: The precooling treatment includes direct precooling with liquid helium, precooling with liquid nitrogen first and then with liquid helium, and precooling with a helium liquefier, which specifically includes: The liquid helium direct precooling specifically includes: The helium storage tank delivers helium to the liquid helium dewar through a fourth pipeline, pressurizing the liquid helium dewar so that the pressure inside the liquid helium dewar is slightly greater than the pressure inside the liquid helium container of the liquid helium storage and transportation container, thereby forming a pressure difference to drive the liquid helium to flow; The liquid helium Dewar transports liquid helium to the liquid helium inner container through a fifth pipeline; The method of precooling with liquid nitrogen first and then with liquid helium comprises: The liquid nitrogen storage tank fills the liquid helium inner container with liquid nitrogen through a twelfth pipeline; When the temperature of the liquid helium inner container reaches a preset temperature, the vacuum pump group is used to evacuate the nitrogen in the liquid helium inner container; The helium storage tank delivers helium to the liquid helium dewar through a fourth pipeline, pressurizing the liquid helium dewar so that the pressure inside the liquid helium dewar is slightly greater than the pressure inside the liquid helium container of the liquid helium storage and transportation container, thereby forming a pressure difference to drive the liquid helium to flow; The liquid helium Dewar transports liquid helium to the liquid helium inner container through a fifth pipeline; The use of a helium liquefier for precooling specifically comprises: The helium liquefier produces low-temperature cold helium or liquid helium, and the helium liquefier delivers low-temperature cold helium or liquid helium to the liquid helium inner container through a seventh pipeline; The liquid helium inner container is cooled by heat exchange with cold helium or liquid helium, and the helium in the liquid helium inner container is heated and then returns to the helium liquefier through a sixth pipeline; Repeat the steps described for precooling using a helium liquefier.

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