System and method for adsorbing and separating helium isotopes at low temperature

Abstract

The invention relates to the technical field of low-temperature adsorption and isotope separation, in particular to a low-temperature helium isotope adsorption separation system and a low-temperature helium isotope adsorption separation method, and the system comprises a gas distribution and gas recovery module which is used for preparing and mixing helium isotope raw material gas and recovering residual gas after an experiment; the static testing unit is used for testing the performance of the adsorbent under a fixed condition; the dynamic low-temperature adsorption unit is used for helium isotope separation under a continuous flow condition; the low-temperature control module is used for providing a stable low-temperature environment and accurate temperature control; wherein an air inlet pipe and an air outlet pipe of the low-temperature control module are respectively subjected to thermal sedimentation and are respectively connected with a flow controller. According to the scheme, the defects that in the prior art, He resources are seriously short, and existing low-temperature adsorption separation helium isotope examples are few are overcome, reference is provided for low-temperature adsorption separation helium isotope adsorbent screening and system design, development of the He separation and purification technology in China is promoted, and dependence on imported He is reduced.

Description

Technical Field

[0001] The present invention relates to the field of cryogenic adsorption technology and isotope separation technology, and in particular to a cryogenic adsorption separation helium isotope system and a cryogenic adsorption separation helium isotope method. Background Art

[0002] As an important resource in the field of advanced scientific research, the demand for high-purity rare gas helium-3 (³He) is increasing day by day. In the fields of nuclear fusion research, low-temperature physics, neutron detectors, etc., ³He is indispensable due to its unique physical and chemical properties.

[0003] Existing methods for separation and purification of helium isotopes include thermal flushing, superleakage, cryogenic distillation, adsorption, and membrane separation. Each method has its own characteristics and scope of application, but in practical applications, it is often limited by cost, efficiency, or complexity. In contrast, cryogenic adsorption has shown potential value in separating and purifying He due to its advantages such as simple structure, low cost and low energy consumption. It is particularly noteworthy that cryogenic adsorption does not require the temperature to be reduced to an extremely low level (such as within 2K), which further reduces the difficulty of operation and technical requirements.

[0004] The working principle of low temperature adsorption is to use the difference in adsorption capacity of adsorbents (such as activated carbon materials) for different helium isotopes to achieve separation and purification. Specifically, activated carbon has different adsorption capacities for He and 4 There are significant differences in the adsorption energy of He, and this characteristic allows for effective enrichment of ³He by properly designing the adsorption process. Despite the many advantages of cryogenic adsorption, there are currently few research examples of cryogenic adsorption separation and purification of helium isotopes at home and abroad, especially in the dynamic separation process, key parameters such as adsorbent type, size, packing density, adsorption column structure design, and dynamic operation temperature, mixed gas flow, operation time, etc. have not been fully explored.

[0005] The static method has been widely used as a method for evaluating adsorbent performance. It measures the pressure drop caused by gas adsorption in the adsorption chamber and calculates the adsorption amount in combination with the gas state equation to obtain the adsorption isotherm, thereby characterizing the adsorption phase equilibrium of the adsorbent under different temperature and pressure conditions. This method is not only easy to operate, but also provides basic data support for screening the optimal adsorbent type and in-depth research on the adsorption mechanism. However, the static method is mainly used for the preliminary evaluation of adsorbent performance under laboratory conditions, and is still insufficient for solving continuous flow separation problems in actual industrial production. Summary of the invention

[0006] The present invention provides a low-temperature adsorption separation system for helium isotopes and a low-temperature adsorption separation method for helium isotopes, which are used to solve the defects of the prior art that ³He resources are seriously short and there are few examples of existing low-temperature adsorption separation of helium isotopes, and provide a reference for adsorbent screening and system design for low-temperature adsorption separation of helium isotopes.

[0007] The present invention provides a low temperature adsorption separation system for helium isotopes, including: a gas distribution and gas recovery module, which is used to prepare and mix helium isotope raw gas and recover the remaining gas after the experiment, including a 300-he gas cylinder, 4 He gas cylinder, circulation pump, flow meter, mixer, vacuum pump unit and pipes and valves of connecting components; static test unit, used to test adsorbent performance under fixed conditions, including copper adsorption chamber, adsorbent, PCT adsorption test instrument, pressure gauge and pipes and valves of connecting components; dynamic low-temperature adsorption unit, used for helium isotope separation under continuous flow conditions, including at least one copper adsorption column, adsorbent, positioning piece, filter, flow meter, helium isotope online detection instrument, pressure gauge, sampling tank and pipes and valves of connecting components; low-temperature control module, used to provide stable low-temperature environment and precise temperature control, including GM refrigerator, temperature controller, heater, vacuum cover, cold screen, radiation protection screen and multi-layer thermal insulation material; wherein the inlet and outlet pipes of the low-temperature control module are respectively heat-precisioned and connected to the flow controller respectively.

[0008] According to one embodiment of the present invention, the gas distribution and gas recovery module also includes a mass flow meter for controlling the flow rate of the helium isotope mixed gas; the vacuum pump unit is used to evacuate the pipeline before the experiment to prevent impurity gases from contaminating the raw gas; after the experiment, the gas generated by desorption and the residual helium isotope gas in the pipeline are recovered by the circulating pump.

[0009] According to one embodiment of the present invention, a thermometer is provided on the adsorption chamber of the static test unit for monitoring temperature changes; the air pipe in the adsorption chamber penetrates into the adsorbent sample, and the pipe wall of the air pipe has evenly distributed openings to facilitate gas diffusion; the PCT adsorption test instrument is used to measure the adsorption isotherm and calculate the adsorption amount at different temperatures and pressures based on the static volume method.

[0010] According to one embodiment of the present invention, the filtration level of the filter of the dynamic cryogenic adsorption unit corresponds to the size of the adsorbent; the helium isotope online detection instrument is used to monitor the helium isotope concentration at the outlet in real time.

[0011] According to one embodiment of the present invention, the inlet and outlet air pipes of the low temperature control module are heat-settled at the cold screen and are respectively connected to the flow controller; the heater includes a heating wire wound around the surface of the sample chamber to perform secondary heating treatment on the adsorbent.

[0012] According to one embodiment of the present invention, the adsorbent needs to undergo a pretreatment process before the experiment, including: placing the adsorbent in a vacuum oven, heating at 200°C for 10 hours, then cooling to room temperature, and then loading it into the adsorption column or the adsorption chamber to activate the adsorbent; after the adsorbent is loaded into the adsorption column or the adsorption chamber, it is heated again at 120°C for 2 hours before each low-temperature adsorption experiment to remove impurity gases in the adsorbent during the transfer process.

[0013] According to one embodiment of the present invention, the dynamic low-temperature adsorption unit includes a plurality of adsorption columns arranged in series or in parallel, and each of the adsorption columns can independently adjust the flow rate and pressure.

[0014] According to one embodiment of the present invention, the system supports multiple cycles of dynamic adsorption separation operations; after each cycle, the adsorbent in the adsorption column is heated and desorbed by the heater, and then low-temperature adsorption is performed again until the required helium isotope concentration standard is reached.

[0015] According to one embodiment of the present invention, the gas distribution and gas recovery module cleans the pipeline by passing helium and evacuating the gas before the experiment to remove impurity gases.

[0016] The present invention also provides a method for separating helium isotopes by low-temperature adsorption, which is used to control the low-temperature adsorption separation system of the above-mentioned embodiment to perform the helium isotope separation process, and the method includes: assembling a test bench; cleaning the pipeline and evacuating the gas in the sample chamber; calibrating the free volume of the cavity and the free volume with the sample at the instrument temperature and the target temperature respectively; gradually cooling the sample chamber to the target temperature and maintaining the vacuum state; performing an adsorption test; recovering the desorbed gas and the residual helium isotope gas in the pipeline; and performing multiple cycles of dynamic adsorption separation operations until the required helium isotope concentration standard is reached.

[0017] The low-temperature adsorption separation system and method for low-temperature adsorption separation of helium isotopes provided by the present invention effectively solve the problems of severe shortage of He resources and scarcity of low-temperature adsorption separation examples in the prior art by integrating advanced gas distribution and gas recovery modules, static test units, dynamic low-temperature adsorption units and low-temperature control modules. The system provides a detailed technical reference for the screening of adsorbents and system design for low-temperature adsorption separation of helium isotopes. Specifically, the present invention uses a combination of dynamic and static methods to evaluate and optimize the performance of the adsorbent under fixed conditions and continuous flow conditions, respectively, to ensure the high efficiency and stability of the adsorption process. At the same time, through precise temperature control and multiple cycles of dynamic adsorption separation operations, high-purity enrichment of He is achieved, and separation efficiency and yield are improved. In addition, components such as the GM refrigerator and cold screen used in the system design ensure the stability and controllability of the low-temperature environment, and reduce energy consumption and technical complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the connection principle of the low-temperature adsorption separation helium isotope system provided by the present invention.

[0020] Figure 2 It is a schematic diagram of the process of the low-temperature adsorption separation of helium isotopes provided by the present invention.

[0021] Figure 3 It is a schematic flow diagram of a static adsorption method of the low-temperature adsorption separation method of helium isotopes provided by the present invention.

[0022] Figure 4 It is a schematic flow diagram of a dynamic adsorption method of the low-temperature adsorption separation method of helium isotopes provided by the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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 are within the scope of protection of the present invention.

[0024] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0025] The purpose of the present invention is to provide a low-temperature adsorption separation system for helium isotopes that combines dynamic and static methods, which mainly solves the serious shortage of He resources and the few existing examples of low-temperature adsorption separation of helium isotopes, and can provide a reference for the screening of adsorbents and system design for low-temperature adsorption separation of helium isotopes. Among them, the low-temperature unit adopts GM refrigerator direct contact refrigeration, which has a wider and more controllable low-temperature temperature zone and more stable temperature control compared to liquid nitrogen and liquid helium immersion cooling. The separation unit can realize dynamic and static detection, set a wider temperature pressure flow rate control range, and design corresponding gas distribution and gas recovery.

[0026] Combine the following Figure 1 The specific embodiment of the low-temperature adsorption separation system of helium isotopes of the present invention is described.

[0027] The present invention provides a low temperature adsorption separation system for helium isotopes, including: a gas distribution and gas recovery module, which is used to prepare and mix helium isotope raw gas and recover the remaining gas after the experiment, including a 300-he gas cylinder, 4 He gas cylinder, circulation pump, flowmeter, mixer, vacuum pump unit and pipes and valves of connecting components; static test unit, used to test the performance of adsorbent under fixed conditions, including copper adsorption chamber, adsorbent, PCT adsorption test instrument, pressure gauge and pipes and valves of connecting components; dynamic low-temperature adsorption unit, used for helium isotope separation under continuous flow conditions, including at least one copper adsorption column, adsorbent, positioning parts, filter, flowmeter, helium isotope online detection instrument, pressure gauge, sampling tank and pipes and valves of connecting components; low-temperature control module, used to provide stable low-temperature environment and precise temperature control, including GM refrigerator, temperature controller, heater, vacuum cover, cold screen, radiation shield and multi-layer insulation material, wherein the inlet and outlet pipes of the low-temperature control module are heat-precipitated respectively and connected to the flow controller respectively. By integrating multiple key modules and their specific components, an efficient, stable and controllable helium isotope separation process is achieved.

[0028] Specifically, the gas distribution and gas recovery module ensures the precise preparation and mixing of helium isotope raw gas during the experiment and effectively recovers the remaining gas after the experiment. 4 He gas cylinders provide high-purity helium isotope raw materials; the circulation pump is used to pump the mixed gas into the test pipeline to ensure uniform gas mixing; the flow meter accurately controls the gas flow rate to ensure the consistency of experimental conditions; the vacuum pump unit pumps the system into a high vacuum state before the experiment to prevent impurity gases from contaminating the raw gas, and recovers the gas generated by desorption and the residual helium isotope gas in the pipeline after the experiment to reduce the loss of precious ³He; pipelines and valves connect the components and control the gas flow direction to ensure the flexibility and safety of the system.

[0029] Secondly, the static test unit is used to evaluate the performance of the adsorbent under fixed conditions. This unit includes an adsorption chamber made of copper to ensure good thermal conductivity and ensure temperature uniformity during the adsorption process; the adsorbent is the core material of the separation process, and different types of adsorbents have different effects on He and 4 He has different adsorption capacities; the PCT adsorption test instrument measures the adsorption isotherm and calculates the adsorption amount at different temperatures and pressures based on the static volume method, providing data support for screening the optimal adsorbent type; the pressure gauge monitors the pressure changes in the adsorption chamber and calculates the adsorption amount in combination with the gas state equation; the indium wire seal ensures the sealing performance of the adsorption chamber to prevent gas leakage from affecting the experimental results; pipes and valves connect the components and control the gas flow direction to ensure the flexibility and safety of experimental operations.

[0030] In addition, the dynamic cryogenic adsorption unit is used for helium isotope separation under continuous flow conditions. The unit contains at least one copper adsorption column, which uses copper material to ensure good heat conduction and ensure temperature uniformity during the adsorption process; adsorbent, positioning parts and copper mesh help fix the adsorbent position to ensure the adsorption effect; the filter prevents the adsorbent powder from entering the subsequent detection equipment and protects the online detection instrument from contamination; the flow meter accurately controls the gas flow rate entering the adsorption column; the helium isotope online detection instrument monitors the helium isotope concentration at the outlet in real time, provides instant feedback to adjust the experimental parameters and improve the separation efficiency; the pressure gauge monitors the pressure change in the adsorption column; the sampling tank is used to collect gas samples after adsorption; the pipeline and valve connect the components and control the gas flow direction to ensure the flexibility and safety of the experimental operation.

[0031] Finally, the cryogenic control module provides a stable low-temperature environment and precise temperature control. The GM refrigerator provides a low-temperature environment as low as 3K, ensuring the extremely low temperature (4.2K) required for the adsorption process; the temperature controller is used in conjunction with the heater to achieve precise control of the sample chamber temperature; the heater includes a heating wire wrapped around the surface of the sample chamber, which can perform secondary heating on the adsorbent when needed; the vacuum cover provides a vacuum environment to reduce external heat transfer; the multi-layer design of the cold screen and the radiation shield effectively isolates external heat and reduces the impact of thermal radiation; the multi-layer insulation material further enhances the insulation effect; the inlet and outlet pipes are respectively heat-deposited through the cold screen to reduce the heat brought by the gas when it enters the low-temperature zone; the flow controller is connected to the inlet and outlet pipes to ensure the stability of the gas flow and assist in temperature control.

[0032] Through the synergistic effect of the above modules and their specific components, the problems of severe shortage of ³He resources and scarcity of low-temperature adsorption separation examples in the existing technology have been solved, providing a detailed technical reference for adsorbent screening and system design for low-temperature adsorption separation of helium isotopes.

[0033] Further, according to a low-temperature adsorption separation helium isotope system of the present invention, the gas distribution and gas recovery module also includes a mass flow meter for controlling the flow rate of the helium isotope mixed gas; the vacuum pump unit is used to evacuate the pipeline before the experiment to avoid impurity gas contamination of the raw gas; after the experiment, the gas generated by desorption and the residual helium isotope gas in the pipeline are recovered by the circulating pump. Specifically, the mass flow meter is used to control the flow rate of the helium isotope mixed gas entering the system. In the dynamic low-temperature adsorption unit, a stable gas flow rate helps to achieve more efficient helium isotope separation. By adjusting the mass flow meter, the required gas flow rate can be accurately set and maintained, thereby optimizing the mass transfer efficiency during the adsorption process. The vacuum pump unit draws the entire system into a high vacuum state before the experiment begins, which not only removes the air and other impurity gases in the pipeline, but also provides a pure environment for subsequent experiments. In addition, after the experiment, the vacuum pump unit can also cooperate with the circulating pump to recover the gas generated by desorption and the residual helium isotope gas in the pipeline, minimizing the loss of precious ³He and improving resource utilization. After the experiment, the circulation pump can collect and recycle the gas desorbed from the adsorption column and the residual helium isotope gas in the pipeline to the designated container. By recycling the gas, the pollution to the environment that may be caused during the experiment can be reduced.

[0034] Furthermore, according to a low-temperature adsorption separation system for helium isotopes of the present invention, a thermometer is provided on the adsorption chamber of the static test unit to monitor temperature changes; the air pipe in the adsorption chamber goes deep into the adsorbent sample, and the pipe wall of the air pipe is evenly distributed with openings to facilitate gas diffusion; the PCT adsorption test instrument is used to measure the adsorption isotherm and calculate the adsorption amount at different temperatures and pressures based on the static volume method. Specifically, temperature fluctuations may affect the selectivity and adsorption capacity of the adsorbent for helium isotopes. The thermometer is installed on the adsorption chamber, which can monitor temperature changes in real time to ensure the stability and accuracy of temperature conditions during the experiment. At the same time, the air pipe in the adsorption chamber goes deep into the adsorbent sample, and the openings evenly distributed on the pipe wall allow the gas to be evenly distributed and fully contact the adsorbent surface, thereby promoting the effective diffusion and adsorption of gas molecules and improving the adsorption efficiency. In addition, the PCT adsorption test instrument is used to measure the adsorption isotherm and calculate the adsorption amount at different temperatures and pressures by the volume method. The instrument can obtain detailed adsorption data under different experimental conditions (such as temperature and pressure), providing an important basis for screening the optimal adsorbent type and studying the adsorption mechanism. Based on these data, the performance of the adsorbent under various conditions can be evaluated, the adsorption parameters can be optimized, and scientific guidance can be provided for system design in practical applications. The static test unit achieves precise control and efficient monitoring of the adsorption process through the synergy of the thermometer, the air pipe that penetrates the adsorbent sample, and the PCT adsorption test instrument, providing detailed adsorption performance data.

[0035] Further, according to a low-temperature adsorption separation helium isotope system of the present invention, the filtration level of the filter of the dynamic low-temperature adsorption unit should be adapted to the size of the adsorbent; the helium isotope online detection instrument is used to monitor the helium isotope concentration at the outlet in real time, thereby providing immediate feedback to adjust the experimental parameters. Specifically, the filter of the dynamic low-temperature adsorption unit uses a high-precision filter to ensure that any fine particles (such as adsorbent powder) generated during the adsorption process will not enter the subsequent detection equipment, avoiding contamination and damage to the helium isotope online detection instrument, thereby improving the reliability of the system and the accuracy of the detection results. At the same time, the helium isotope online detection instrument is used to monitor the helium isotope concentration at the outlet in real time, provide immediate feedback, and enable the operator to quickly adjust the experimental parameters, such as gas flow rate, temperature and pressure, to optimize the adsorption process. By continuously monitoring the helium isotope concentration at the outlet, problems that may affect the separation effect can be discovered and corrected in a timely manner, ensuring the efficiency and stability of the separation process, while providing valuable information for subsequent data analysis and adsorption mechanism research, which is helpful to further improve and optimize the adsorption separation technology.

[0036] Further, according to a low-temperature adsorption separation helium isotope system of the present invention, the inlet and outlet pipes of the low-temperature control module are heat-deposited and respectively connected to the flow controller; the heater includes a heating wire wrapped around the surface of the sample chamber to perform secondary heating treatment on the adsorbent. Specifically, the inlet and outlet pipes are designed for heat deposition at the cold screen and are respectively connected to the flow controller, which effectively reduces the heat brought by the gas when entering the low-temperature zone and ensures accurate temperature control. The heat deposition process allows the heat in the gas to be fully removed before entering the low-temperature environment, thereby avoiding temperature fluctuations caused by bringing in too much heat and ensuring the stability and controllability of the temperature during the adsorption process. The flow controller accurately controls the gas flow rate of the inlet and outlet pipes to ensure the consistency and repeatability of the experimental conditions and optimize the mass transfer efficiency. The heater includes a heating wire wrapped around the surface of the sample chamber, which can perform secondary heating treatment on the adsorbent when needed. It can not only pre-treat the adsorbent before the experiment to remove impurity gases that may be carried in the adsorbent, but also desorb the adsorbent after the adsorption is completed, promote the release of the adsorbed gas, and improve the recycling efficiency of the system. By precisely controlling the heating power and time of the heating wire, the temperature of the adsorbent can be finely adjusted to ensure that the adsorbent operates in the best working state and improve the effects of adsorption and desorption.

[0037] Furthermore, according to a low-temperature adsorption separation helium isotope system of the present invention, the adsorbent needs to undergo a pretreatment process before the experiment, including: placing the adsorbent in a vacuum oven, heating at 200°C for 10 hours, then cooling to room temperature, and then loading it into an adsorption column or adsorption chamber to achieve the purpose of activating the adsorbent; after loading the adsorbent into the adsorption column or adsorption chamber, it needs to be heated again at 120°C for 2 hours before each low-temperature adsorption experiment to remove the impurity gas in the transfer process of the adsorbent. This pretreatment process is intended to thoroughly remove the impurity gas that may exist inside the adsorbent to ensure that it can efficiently and accurately adsorb the target helium isotope during the experiment.

[0038] Specifically, the adsorbent is placed in a vacuum oven and heated under a high vacuum environment. By continuously heating at a high temperature of 200°C for 10 hours, the moisture and other volatile impurity gases remaining in the micropores and surface of the adsorbent can be effectively driven out, the original activity of the adsorbent can be restored, and its adsorption performance can be improved. It not only enhances the selectivity and adsorption capacity of the adsorbent, but also reduces the nonspecific adsorption caused by the presence of impurity gases. After heating, the adsorbent needs to be gradually cooled to room temperature to avoid damage to the adsorbent structure due to sudden temperature changes and to ensure the stability of its physical and chemical properties. The cooled adsorbent is then loaded into an adsorption column or adsorption chamber, ready for actual adsorption experiments.

[0039] In order to prevent the inhalation of impurity gases from the outside air during the transfer process, the entire operation should be completed in the shortest possible time and can be carried out in an environment filled with inert gas (such as helium) to keep the adsorbent pure. In addition, after the adsorbent is loaded into the adsorption column or adsorption chamber, it must be heated again at 120°C for 2 hours in a high vacuum environment before each low-temperature adsorption experiment, in order to remove the impurity gases that may remain during the adsorbent transfer process, further ensure that the adsorbent is in the best working condition, and thus ensure the accuracy and reliability of the experimental results. This pretreatment process is conducive to completely removing the impurity gases that may exist inside the adsorbent, ensuring that it can efficiently and accurately adsorb the target helium isotopes during the experiment.

[0040] Further, according to a low-temperature adsorption separation system of helium isotopes of the present invention, the dynamic low-temperature adsorption unit includes a plurality of adsorption columns arranged in series or in parallel, and each adsorption column can independently adjust the flow rate and pressure. The dynamic low-temperature adsorption unit realizes highly flexible control and efficient management of the helium isotope separation process by arranging a plurality of adsorption columns in series or in parallel and giving each adsorption column the ability to independently adjust the flow rate and pressure.

[0041] Specifically, multiple adsorption columns can be connected in series or in parallel to accommodate separation tasks of different scales. In the series configuration, the gas passes through multiple adsorption columns in sequence, gradually improving the separation effect; while in the parallel configuration, the gas can pass through multiple adsorption columns at the same time, increasing the processing capacity and operational flexibility.

[0042] Each adsorption column is equipped with an independent flow meter and pressure control device, which can accurately adjust the gas flow rate and pressure entering each adsorption column. This independent adjustment capability allows operators to optimize the settings for the adsorbent characteristics in different adsorption columns, ensuring that each adsorption column works under optimal conditions. For example, in some cases, one adsorption column may require a higher flow rate to achieve rapid adsorption, while another adsorption column may require a lower pressure to ensure the best adsorption performance of the adsorbent. By fine-tuning these parameters, the working efficiency of each adsorption column can be maximized, thereby improving the separation effect of the overall system.

[0043] In addition, the design of multiple adsorption columns also supports multiple cycles of dynamic adsorption separation operations. When an adsorption column reaches saturation, the gas can be directed to other unsaturated adsorption columns by switching valves to continue the adsorption process. The saturated adsorption column can be desorbed by heating to restore its adsorption capacity and prepare for the next round of adsorption operation.

[0044] Furthermore, according to a low-temperature adsorption separation system of helium isotopes of the present invention, the system supports multiple cycles of dynamic adsorption separation operations; after each cycle, the adsorbent in the adsorption column is heated and desorbed by a heater, and then low-temperature adsorption is performed again until the required helium isotope concentration standard is reached. The system can gradually improve the purity of helium isotopes in continuous operation to ensure that the final product reaches a high concentration standard.

[0045] Specifically, during each cycle, the adsorption column first adsorbs He and 4 He, using the different adsorption energy differences between different isotopes and adsorbents to achieve preliminary separation. When the adsorption column reaches saturation or the set adsorption time is over, the system automatically switches to desorption mode. At this time, the heater (including the heating wire wrapped around the surface of the adsorption column) performs a precisely controlled heating treatment on the adsorbent to fully release the gas molecules inside the adsorbent and restore its original adsorption capacity. The desorbed gas (mainly unadsorbed 4 He and other impurity gases) are collected and processed, while the remaining high-concentration ³He is recycled for subsequent operations. Subsequently, the system re-enters the low-temperature adsorption stage to continue adsorbing and separating new helium isotope mixed gases. By repeating the above adsorption-desorption cycle, the system can gradually enrich ³He and eventually reach the required high concentration standard.

[0046] This cyclic operation design not only makes efficient use of the adsorption capacity of the adsorbent, reduces the replacement frequency and operating costs, but also provides the opportunity to flexibly adjust parameters. After each cycle, the adsorption and desorption conditions (such as temperature, pressure and flow rate) can be optimized according to the actual separation effect to improve the separation efficiency. In addition, the multi-cycle design improves the fault tolerance and stability of the system. Even if deviations occur in some cycles, subsequent cycles can be corrected to ensure the quality of the final product. By recovering and reusing the desorbed gas, the system also reduces the waste of He and improves resource utilization.

[0047] Furthermore, according to a low-temperature adsorption separation system of helium isotopes of the present invention, the gas distribution and gas recovery module uses high-purity helium gas and vacuum to clean the pipeline before the experiment to remove impurity gases. Specifically, before the experiment starts, the pipeline of the entire system is evacuated to a high vacuum state by turning on the vacuum pump unit to remove the residual air and other impurity gases that may exist in the pipeline. After the vacuum is completed, the system will be filled with high-purity helium (usually 4 He) and keep it for a while to allow helium to fully replace the remaining gas in the pipeline. As an inert gas, helium will not react with the adsorbent and can effectively remove the remaining impurity gas molecules. Then, start the vacuum pump unit again to extract the helium and the accompanying impurity gas in the pipeline to ensure that the inside of the pipeline reaches a very high purity. This process can be repeated many times to completely eliminate any potential sources of contamination and ensure the absolute purity of the experimental environment.

[0048] According to a preferred embodiment of the present invention, a low temperature adsorption separation system for helium isotopes is described. Figure 1 As shown, the present invention includes a gas distribution and gas recovery module, a static test unit, a dynamic low-temperature adsorption unit and a low-temperature control module.

[0049] In the flow passage of the gas distribution and gas recovery module, the flow rate of the passage can be adjusted according to the reading of the flow meter. 4 He is mixed in proportion, and the circulating pump pumps the mixed gas into the test pipeline. The mixed gas is selected to pass into the static test branch or the dynamic test branch through the valve. Before the start of the entire experiment, all pipelines should be cleaned by the vacuum pump unit and helium to ensure that the pipelines are clean and free of gas impurities. The recovery gas line is composed of a pump and a tank, etc., which is used to recover the gas generated by desorption and the residual helium isotope gas in the pipeline.

[0050] The separation path of the low-temperature static method includes raw gas, PCT adsorption test instrument, adsorption chamber A, molecular pump, vacuum pump, heating unit, pipelines, valves and other components. The test of static method low-temperature separation of helium isotopes can obtain data by operating the PCT adsorption test instrument. After the adsorption is saturated, the remaining gas can be pumped into the recovery gas cylinder by the vacuum pump for testing. The volume of the sample chamber should not be too large or too small, generally within 20 milliliters, to ensure that the detection effect of adsorption separation is obvious. Before the experiment, the adsorbent needs to be pre-treated by vacuum heating and activation. This process is completed by the heating unit in conjunction with the vacuum pump to remove impurity gases in the adsorbent.

[0051] The separation path of the low temperature dynamic method includes the secondary heat exchanger of the GM refrigerator, adsorption column B, helium isotope online detection instrument, heating unit, vacuum pump, pipeline and valve and other components. The adsorption column B is cooled to the target low temperature by direct contact with the secondary heat exchanger, and the mixed gas provided by the gas distribution and gas recovery module enters the adsorption column B at a rate controlled by the mass flow meter. The number of adsorption columns can be set to one or more as needed, and can be configured in series or parallel as required. 4 The adsorption energy of He is different. It is estimated that the final He concentration can reach 99.99% after multiple low-temperature adsorptions. When the adsorption column reaches saturation, turn on the heating unit and pump group to 4 Before the experiment, the adsorbent also needs to be pre-treated by vacuuming and heating to ensure its optimal working condition.

[0052] The low-temperature adsorption separation helium isotope system realizes an efficient, stable and controllable helium isotope separation process through the synergistic effect of the above modules and their specific components, solving the problems of severe shortage of He resources and scarcity of low-temperature adsorption separation examples in the existing technology, and providing a detailed technical reference for the adsorbent screening and system design of low-temperature adsorption separation of helium isotopes.

[0053] The low-temperature adsorption separation method of helium isotopes provided by the present invention is described below. The low-temperature adsorption separation method of helium isotopes described below and the low-temperature adsorption separation system of helium isotopes described above can be referenced to each other.

[0054] The present invention also provides a method for separating helium isotopes by low-temperature adsorption, which is used to control the low-temperature adsorption and separation of helium isotopes system of the above embodiment to perform the process of separating helium isotopes. Figure 2 FIG. 1 is a schematic flow diagram of the method for separating helium isotopes by low-temperature adsorption provided by the present invention, such as Figure 2 As shown, the method includes the following: Step 11. Assemble the test bench. Ensure that the sample chamber has good sealing performance and complete the connection of each component. Specifically, first install all modules (gas distribution and gas recovery module, static test unit, dynamic low-temperature adsorption unit and low-temperature control module) accurately in place according to the design requirements to ensure that each interface is tightly connected without leakage risk. Use indium wire or other high-sealing materials for sealing, especially key parts such as the adsorption chamber and adsorption column, to ensure that there will be no gas leakage during the experiment. At the same time, check and confirm that all valves, flow meters and other control instruments are in normal working condition to ensure the operational flexibility and safety of the entire system.

[0055] Step 12: Clean the pipeline and evacuate the gas in the sample chamber. Remove impurity gases by passing helium and evacuating the chamber. Specifically, before the experiment begins, use a vacuum pump unit to evacuate the pipeline of the entire system to a high vacuum state to remove residual air and other impurity gases that may exist in the pipeline. Then fill it with high-purity helium to fully replace the remaining gas in the pipeline, and then start the vacuum pump unit to extract the helium and the accompanying impurity gases together to ensure that the inside of the pipeline reaches an extremely high degree of purity. This process can be repeated many times to completely eliminate any potential sources of contamination and ensure the absolute purity of the experimental environment.

[0056] Step 13. Calibrate the free volume of the cavity and the sample at the instrument temperature and the target temperature. Specifically, first measure the free volume of the cavity (when not filled with adsorbent) at room temperature of the instrument and record the data as a baseline value. Then, load the pretreated adsorbent into the sample chamber and measure the free volume with adsorbent again. This process needs to be repeated under different temperature conditions, including target low temperature conditions, to obtain the adsorption phase equilibrium parameters at different temperatures. With these data, the PCT adsorption test instrument can be calibrated to ensure the accuracy of subsequent adsorption calculations.

[0057] Step 14: Gradually cool the sample chamber to the target temperature and keep it in a vacuum state. Specifically, use a GM refrigerator to gradually lower the temperature of the sample chamber until the predetermined target low temperature (such as 4.2K) is reached. During this process, keep the sample chamber in a vacuum state to prevent outside gas from entering. The design of the cold shield and radiation shield effectively isolates external heat to ensure the stability and controllability of the sample chamber temperature. After the temperature drops to the target value, continue to maintain the vacuum state for a period of time to ensure that the temperature is evenly distributed and thermal equilibrium is achieved.

[0058] Step 15, conduct an adsorption test. For the static test unit, operate the adsorption instrument to conduct an adsorption test after the target temperature stabilizes; for the dynamic low-temperature adsorption unit, after cooling to the target temperature, adjust the flowmeter to maintain a constant rate of helium isotope gas, and monitor the helium isotope concentration at the outlet. Specifically, after the target temperature of the static test unit stabilizes, the inlet and outlet valves are closed, the adsorption isotherm is measured by the PCT adsorption test instrument, and the adsorption amount at different temperatures and pressures is calculated based on the volume method. After adsorption saturation, turn on the vacuum pump to draw the remaining gas into the recovery gas cylinder. After the dynamic low-temperature adsorption unit is cooled to the target temperature, adjust the mass flowmeter to maintain a constant rate of helium isotope mixed gas. The helium isotope online detection instrument monitors the helium isotope concentration at the outlet in real time, provides instant feedback to adjust the experimental parameters, and ensures the efficiency and stability of the separation process.

[0059] Step 16, recover the desorbed gas and the residual helium isotope gas in the pipeline. After the low-temperature adsorption is completed, the heater is used to heat and desorb the adsorbent in the adsorption column, and then the desorbed gas and the residual helium isotope gas in the pipeline are recovered through the circulation pump and valve. Specifically, when the adsorption column reaches saturation, turn on the heating wire wrapped around the surface of the adsorption column, gradually heat it to the set temperature, and cause the adsorbent to release the adsorbed helium isotope gas. At this time, start the vacuum pump and the circulation pump to collect the desorbed gas into a designated container for the next round of experiments.

[0060] Step 17: Repeat the dynamic adsorption and separation operation for multiple cycles, and repeat the above dynamic adsorption and separation experiment as needed until the required helium isotope concentration standard is reached. Specifically, after each cycle, the adsorbent in the adsorption column is heated and desorbed by the heater to restore its adsorption capacity. Subsequently, the low-temperature adsorption stage is re-entered to continue the adsorption and separation of the new helium isotope mixed gas. By continuously optimizing the adsorption and desorption conditions (such as temperature, pressure and flow rate), the enrichment of ³He is gradually increased, and finally the required high concentration standard is reached.

[0061] Based on the low-temperature adsorption separation system of helium isotopes described above, the above-mentioned low-temperature adsorption separation method of helium isotopes can be further divided into a static adsorption method and a dynamic adsorption method.

[0062] Among them, Figure 3 As shown, the static adsorption method includes: Step 21, system preparation and cleaning. Specifically include: assembling the test bench to ensure that the sample chamber has good sealing performance and completing the connection of various components; as well as cleaning the pipeline and evacuating the gas in the sample chamber, and removing impurity gases by passing helium and vacuuming. Specifically, before the experiment begins, use the vacuum pump unit to evacuate the pipeline of the entire system into a high vacuum state to remove residual air and other impurity gases that may exist in the pipeline. Then fill it with high-purity helium to fully replace the remaining gas in the pipeline, and then start the vacuum pump unit to extract the helium and the accompanying impurity gas together to ensure that the inside of the pipeline reaches an extremely high degree of purity. This process can be repeated many times to completely eliminate any potential sources of contamination.

[0063] Step 22, calibrate the free volume. Specifically, calibrate the free volume of the empty cavity and the free volume with the sample, and calibrate the free volume of the empty cavity (when not filled with adsorbent) and the free volume with adsorbent at the instrument temperature and the target temperature. It needs to be repeated under different temperature conditions, including the target low temperature condition, to obtain the adsorption phase equilibrium parameters at different temperatures. With these data, the PCT adsorption test instrument can be calibrated to ensure the accuracy of the subsequent adsorption calculation.

[0064] Step 23: Cool down the sample chamber. Use a GM refrigerator to gradually lower the temperature of the sample chamber until it reaches the predetermined target low temperature (e.g., 4.2K). During this process, keep the sample chamber evacuated to prevent outside gas from entering. The design of the cold shield and radiation shield effectively isolates external heat to ensure the stability and controllability of the sample chamber temperature. After the temperature drops to the target value, continue to maintain the evacuation state for a period of time to ensure that the temperature is evenly distributed and thermal equilibrium is achieved.

[0065] Step 24, adsorption test. After the target temperature is stable, close the inlet and outlet valves. Measure the adsorption isotherm with the PCT adsorption test instrument, and calculate the adsorption amount at different temperatures and pressures based on the volume method. After adsorption saturation, turn on the vacuum pump to pump the remaining gas into the recovery gas cylinder for testing.

[0066] Step 25, gas recovery: The desorbed gas and the residual helium isotope gas in the pipeline are recovered, and the adsorbent in the adsorption column is heated and desorbed by a heater, and then the desorbed gas and the residual helium isotope gas in the pipeline are recovered by a circulation pump and a valve.

[0067] Furthermore, the present invention provides a static method experimental operation instruction. In order to ensure that the sample chamber has good sealing performance, the new sample chamber should be tested for vacuum degree by vacuum method using a helium mass spectrometer leak detector before use. A thermometer is attached to the upper and lower surfaces of the sample chamber, a heating wire is wrapped around the outer edge of the copper column of the sample chamber, and multiple layers of materials are wrapped, and a cold shield and a vacuum cover are installed in sequence. After ensuring that the pipelines of the adsorption instrument and the refrigerator are well connected, the experiment can be prepared.

[0068] Before turning on the adsorption instrument, you must ensure that the pressure of each gas cylinder is set within a reasonable range. First, start the dry pump and select the built-in pipeline cleaning program of the adsorption instrument. This program actually replaces the pipeline gas with helium. The specific implementation method is: use the nitrogen in the nitrogen bottle to drive the opening and closing of the built-in valve of the instrument. First, open the valves of each pipeline in the system to evacuate with the help of the dry pump, then close the external valve to stop the vacuum and open the helium bottle pressure reducing valve to add helium to the pipeline for purging. When the pipeline is filled with helium, that is, when the cavity reaches a pressure close to one atmosphere, close the pressure reducing valve, open the pump line valve for vacuuming; then close the pump line valve and fill it with helium again. Repeat the above steps three times to completely remove the impurity gas and evacuate the sample chamber.

[0069] Before the adsorption test, three volume parameters from the valve outlet of the adsorption instrument to the sample chamber need to be obtained: the free volume of the cavity at the instrument temperature, the free volume with the sample at the instrument temperature, and the free volume of the cavity at the target temperature. The operation steps of volume calibration are to select the calibration volume function of the adsorption instrument, reasonably set the test time and number of rounds, and the instrument will give free volume data after the program ends, which needs to be recorded manually.

[0070] Next, while keeping the sample chamber evacuated, turn on the mechanical pump to pump the vacuum to 10 -1 Pa, and then turn on the molecular pump to further evacuate to 10 -3 Pa. Then turn on the water cooling unit and turn the refrigerator knob to ON, and control the heating through the temperature controller until the target temperature is reached.

[0071] The calibration of the cavity free volume at the target temperature is the same as the calibration at the instrument temperature. It should be noted that vacuum treatment should be performed after the calibration.

[0072] After completing the above steps, you can turn the refrigerator knob to OFF in sequence and turn off the water cooling unit. Use the temperature controller to heat it back to above 273K, and gradually turn off the molecular pump and mechanical pump. Remove the bolts on the flange of the vacuum cover, open the reserved baffle valve to let in air to break the vacuum in order to remove the vacuum cover, then remove the cold shield, and finally take out the sample chamber. Reload the activated carbon activated by heating at 200°C for 10 hours in the sample chamber and seal it with indium wire. Since impurity gases may be inhaled when transferring the activated carbon, it is necessary to heat and vacuumize it at 150°C for 1 hour after sealing. After cooling to room temperature, assemble the cold shield and vacuum cover in sequence, and calibrate the volume. The steps are the same as above.

[0073] During the low-temperature adsorption test phase, the temperature must first be lowered to the target temperature, and the sample chamber must be vacuumed during this period. After the target temperature stabilizes, operate the adsorption instrument to perform the adsorption test. The outlet pressure of the test gas pressure reducing valve should be set to a reasonable operating pressure, and pay attention to setting the test method and parameters of the instrument. The volume parameters input into the instrument include: the free volume when the instrument temperature has a sample and the free volume when the target temperature has a sample. The latter is obtained by subtracting the activated carbon skeleton volume from the free volume of the target temperature cavity, while the activated carbon skeleton volume is obtained by subtracting the free volume of the instrument temperature cavity from the free volume of the instrument temperature sample.

[0074] In addition, if Figure 4 As shown, the dynamic adsorption method includes: Step 31: System preparation and cleaning. Clean the entire system by passing helium gas and evacuating the system to remove impurities. Pay attention to the early leak detection to ensure that the system leakage rate is within 10 -9 Within.

[0075] Step 32, adsorbent activation. After the adsorption column is filled and installed, it is not connected to the secondary cold screen of the refrigerator yet. It is necessary to activate the adsorbent by heating and vacuuming to remove the gas impurities originally carried.

[0076] Step 33, equipment startup. Turn on the mechanical pump, molecular pump, water cooling and refrigerator in sequence, and after cooling to the target temperature and maintaining stability, the dynamic adsorption separation experiment can be carried out.

[0077] Step 34, experimental monitoring and recording. Record the changes in the pressure readings before and after the adsorption column, adjust the flowmeter to maintain a constant rate of helium isotope gas, and stop introducing gas when the inlet and outlet pressures stabilize at similar readings. The helium isotope online detection instrument can quickly and accurately obtain the outlet concentration percentage after adjustment.

[0078] Step 35, sampling and recovery. After low-temperature adsorption is completed, close the valve on the sampling tank first to facilitate third-party inspection and comparison or other purposes. Stop refrigeration and use the circulation pump and various valves to recover the desorbed and pipeline residual gas.

[0079] Step 36: Repeat the operation multiple times. If the sample gas concentration does not reach the target, the dynamic adsorption separation operation can be repeated multiple times to gradually increase the enrichment of He and eventually reach the required high concentration standard.

[0080] Furthermore, the present invention also provides an operating instruction for the dynamic method experiment. First, the entire system needs to be cleaned by passing helium and evacuating the pipeline to remove impurity gases, and ensure that the system leakage rate is within 10 -9After the adsorption column is filled and installed, it is not immediately connected to the secondary cold screen of the refrigerator, but firstly turned on the heating and vacuum to activate the adsorbent to remove the gas impurities originally carried by it.

[0081] Turn on the mechanical pump, molecular pump, water cooling and refrigerator in sequence. After cooling to the target temperature and maintaining stability, the dynamic adsorption separation experiment can be carried out. During the experiment, it is necessary to record the changes in the pressure readings before and after the adsorption column. Adjust the flowmeter to maintain a constant rate of helium isotope gas. When the inlet and outlet pressures stabilize at similar readings, stop passing the gas. The helium isotope online detection instrument can quickly and accurately detect the helium isotope concentration of the outlet gas after adjustment and provide the outlet concentration percentage.

[0082] After low temperature adsorption is completed, the valve on the sampling tank is closed first to facilitate third-party inspection or other purposes. After stopping refrigeration, the circulating pump and various valves are used to recover the desorbed and residual gas in the pipeline. If the sampled gas concentration does not reach the target, the dynamic adsorption separation operation can be repeated multiple times to gradually increase the enrichment of He and eventually reach the required high concentration standard.

[0083] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or modes described in this specification and the features of the different embodiments or modes, without contradiction.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low temperature adsorption separation system for helium isotopes, characterized in that: include: Gas distribution and gas recovery module, used to prepare and mix helium isotope raw gas and recover the remaining gas after the experiment, including ³He gas cylinder, 4 He gas cylinders, circulation pumps, flow meters, mixers, vacuum pump units, and pipes and valves connecting components; Static test unit, used to test the performance of adsorbent under fixed conditions, including copper adsorption chamber, adsorbent, PCT adsorption test instrument, pressure gauge and pipes and valves connecting components; A dynamic cryogenic adsorption unit for helium isotope separation under continuous flow conditions, comprising at least one copper adsorption column, an adsorbent, a positioning member, a filter, a flow meter, an online helium isotope detection instrument, a pressure gauge, a sampling tank, and pipes and valves connecting the components; Low temperature control module, used to provide a stable low temperature environment and precise temperature control, including GM refrigerator, temperature controller, heater, vacuum cover, cold shield, radiation shield and multi-layer insulation material; The inlet and outlet air pipes of the low temperature control module are respectively heat-settled and connected to flow controllers.

2. The low temperature adsorption separation helium isotope system according to claim 1, characterized in that: The gas distribution and gas recovery module also includes a mass flow meter for controlling the flow rate of the helium isotope mixed gas; The vacuum pump unit is used to evacuate the pipeline before the experiment to prevent impurity gases from contaminating the raw gas; After the experiment, the gas generated by desorption and the residual helium isotope gas in the pipeline are recovered by the circulation pump.

3. The low temperature adsorption separation helium isotope system according to claim 1, characterized in that: The adsorption chamber of the static test unit is provided with a thermometer for monitoring temperature changes; The air pipe in the adsorption chamber penetrates into the adsorbent sample, and the pipe wall of the air pipe is evenly distributed with openings to facilitate gas diffusion; The PCT adsorption test instrument is used to measure the adsorption isotherm and calculate the adsorption amount at different temperatures and pressures based on the static volume method.

4. The low temperature adsorption separation helium isotope system according to claim 1, characterized in that: The filtration level of the filter of the dynamic cryogenic adsorption unit corresponds to the size of the adsorbent; The helium isotope online detection instrument is used to monitor the helium isotope concentration at the outlet in real time.

5. The low temperature adsorption separation helium isotope system according to claim 1, characterized in that: The inlet and outlet air pipes of the low temperature control module are heat-settled at the cold screen and are respectively connected to the flow controller; The heater comprises a heating wire wound on the surface of the sample chamber to perform secondary heating treatment on the adsorbent.

6. The low temperature adsorption separation helium isotope system according to claim 1, characterized in that: The adsorbent needs to undergo a pretreatment process before the experiment, including: The adsorbent is placed in a vacuum oven, heated at 200° C. for 10 hours, then cooled to room temperature, and then loaded into the adsorption column or the adsorption chamber to activate the adsorbent; After the adsorbent was loaded into the adsorption column or the adsorption chamber, it was heated again at 120° C. for 2 hours before each low-temperature adsorption experiment to remove impurity gases in the adsorbent during the transfer process.

7. The low temperature adsorption separation helium isotope system according to claim 1, characterized in that: The dynamic low-temperature adsorption unit comprises a plurality of adsorption columns arranged in series or in parallel, and each of the adsorption columns can independently adjust the flow rate and pressure.

8. The low temperature adsorption separation helium isotope system according to any one of claims 1 to 7, characterized in that: The system supports multiple cycles of dynamic adsorption and separation operations; After each cycle, the heater is used to heat and desorb the adsorbent in the adsorption column, and then low-temperature adsorption is performed again until the required helium isotope concentration standard is reached.

9. The low temperature adsorption separation helium isotope system according to any one of claims 1 to 7, characterized in that: The gas distribution and gas recovery module uses helium gas and vacuum to clean the pipeline before the experiment to remove impurity gases.

10. A method for separating helium isotopes by low temperature adsorption, characterized in that: The method for controlling the low-temperature adsorption helium isotope separation system according to any one of claims 1 to 9 to perform a helium isotope separation process comprises: Assemble the test bench; Clean the pipeline and evacuate the gas in the sample chamber; Calibrate the free volume of the empty cavity and with sample at the instrument temperature and target temperature respectively; The sample chamber is gradually cooled down to the target temperature and maintained in a vacuum state; Conduct adsorption tests; Recover the desorbed gas and the residual helium isotope gas in the pipeline; The dynamic adsorption separation operation is repeated multiple times until the required helium isotope concentration standard is reached.

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