A method and system for extracting helium-3 from a high-tritium heavy water gas mixture

Abstract

The embodiment of the application provides a method and system for extracting helium-3 in high tritium heavy water mixed gas. The method comprises purification treatment, low-temperature pre-fractionation treatment and dehydrogenation treatment. The method can extract helium-3 generated in the storage process of high tritium heavy water, provides a new way for obtaining helium-3, thereby improving the yield of helium-3. In addition, the method has the advantages of advanced process, high separation degree and high quality of helium-3 gas, and the helium-3 generated in the storage process of high tritium heavy water can be fully obtained, thereby improving the energy utilization rate.

Description

Technical Field

[0001] This application relates to the field of chemical technology, and in particular to a method and system for extracting helium-3 from a high-tritium heavy water mixture. Background Technology

[0002] Helium-3 is an isotope of helium. Helium-3 has unique physical properties and is increasingly being used in many fields such as neutron detection, cryogenic engineering, nuclear energy development, medicine, geography, and astronomy. Helium-3 is known as one of the most precious rare gases, and a stable supply of high-quality helium-3 gas is one of the important supporting technologies for the development of quantum technology.

[0003] Helium-3 is extremely rare in related technologies, and there are few ways to obtain it and the process is relatively difficult, resulting in a relatively low production volume of helium-3. Summary of the Invention

[0004] In view of this, embodiments of this application provide a method and system for extracting helium-3 from a high-tritium heavy water mixture, aiming to provide a new approach to obtain helium-3 with lower difficulty, so as to increase the yield of helium-3.

[0005] To achieve the above objectives, one embodiment of this application provides a method for extracting helium-3 from a high-tritium heavy water mixture, wherein the mixture includes a covering gas, the covering gas being nitrogen, characterized in that the extraction method includes:

[0006] Purification treatment: The mixed gas containing helium-3 is purified to remove water, water vapor, CO2, hydrocarbons, some N2, some O2 and some hydrogen isotope combination gas from the mixed gas and obtain the first stage crude helium gas;

[0007] Low-temperature pre-distillation treatment: The first-stage crude helium gas is subjected to low-temperature pre-distillation treatment to remove residual N2 and O2 in the first-stage crude helium gas and obtain the second-stage crude helium gas;

[0008] Dehydrogenation treatment: The crude helium gas in the second stage is subjected to dehydrogenation treatment to remove the residual hydrogen isotope combination gas in the crude helium gas in the second stage.

[0009] In one embodiment, the purification process specifically includes:

[0010] Catalytic oxidation treatment: The mixed gas containing helium-3 is subjected to catalytic oxidation treatment to remove trace amounts of hydrocarbons and some hydrogen isotope combination gases from the mixed gas and obtain a first mixture;

[0011] Low-temperature cooling treatment: The first mixture is subjected to low-temperature cooling treatment to remove water and some water vapor from the first mixture and obtain a second mixture;

[0012] Low-temperature adsorption treatment: The second mixture is subjected to low-temperature adsorption treatment to remove CO2, part of N2, part of O2 and residual water vapor from the second mixture and obtain the first stage crude helium gas.

[0013] In one embodiment, the catalytic oxidation treatment step specifically includes:

[0014] Under high temperature conditions, the mixed gas is controlled to be introduced into copper oxide so that the copper oxide reacts with the hydrocarbon and hydrogen isotope combination gas in the mixed gas to produce a redox reaction.

[0015] In one embodiment, the low-temperature cooling process specifically includes:

[0016] The first mixture is controlled to flow through chilled water for low-temperature cooling.

[0017] In one embodiment, the low-temperature adsorption treatment step specifically includes:

[0018] The second mixture is adsorbed at low temperature using a low-temperature adsorption material at liquid nitrogen temperature.

[0019] In one embodiment, the low-temperature adsorption material includes at least one of molecular sieve and activated carbon.

[0020] In one embodiment, the dehydrogenation treatment step specifically includes:

[0021] Palladium membrane permeation treatment: The second-stage crude helium gas is subjected to palladium membrane permeation treatment to remove some of the hydrogen isotope combination gas in the second-stage crude helium gas and obtain the third-stage crude helium gas;

[0022] Cryogenic adsorption treatment: The crude helium gas in the third stage is subjected to cryogenic adsorption treatment to remove the residual hydrogen isotope combination gas in the crude helium gas in the third stage.

[0023] In one embodiment, the palladium membrane permeation treatment step specifically includes:

[0024] A measured amount of hydrogen gas is added to the crude helium gas in the second stage;

[0025] The second-stage crude helium gas, to which a measured amount of hydrogen gas has been added, is permeated through a palladium membrane to remove some of the hydrogen isotope combination gas from the second-stage crude helium gas.

[0026] In one embodiment, the ultra-low temperature adsorption treatment step specifically includes:

[0027] Under conditions below 0.1K, the crude helium gas of the third stage is adsorbed at ultra-low temperatures using ultra-low temperature adsorption materials.

[0028] Another aspect of this application provides a system for extracting helium-3 from a high-tritium heavy water mixture, applicable to the extraction method for helium-3 from a high-tritium heavy water mixture described in any of the above embodiments. The extraction system includes:

[0029] The purification unit includes a catalytic oxidation unit, a cryogenic cooling unit, and a cryogenic adsorption unit. The catalytic oxidation unit is used to catalytically oxidize the mixed gas containing helium-3 to remove trace amounts of hydrocarbons and some hydrogen isotope combinations to obtain a first mixture. The cryogenic cooling unit is used to cryogenically cool the first mixture to remove water and some water vapor to obtain a second mixture. The cryogenic adsorption unit is used to cryogenically adsorb the second mixture to remove CO2, some N2, some O2, and residual water vapor to obtain the first-stage crude helium gas.

[0030] The low-temperature pre-distillation unit is used to perform low-temperature pre-distillation on the first-stage crude helium gas to remove residual N2 and O2 from the first-stage crude helium gas and obtain the second-stage crude helium gas.

[0031] The dehydrogenation treatment unit includes a palladium membrane permeation treatment unit and an ultra-low temperature adsorption treatment unit. The palladium membrane permeation treatment unit is used to perform palladium membrane permeation treatment on the second-stage crude helium gas to remove some of the hydrogen isotope combination gas in the second-stage crude helium gas and obtain the third-stage crude helium gas. The ultra-low temperature adsorption treatment unit is used to perform ultra-low temperature adsorption treatment on the third-stage crude helium gas to remove the residual hydrogen isotope combination gas in the third-stage crude helium gas.

[0032] The method for extracting helium-3 from a high-tritium heavy water mixture according to this application embodiment uses nitrogen as a covering gas. During storage, a mixed gas formed by mixing the covering gas with helium-3 and other gases obtained from tritium decay is used as raw material. The mixed gas undergoes purification, low-temperature pre-distillation, and dehydrogenation treatments in sequence to gradually remove water, water vapor, CO2, N2, O2, hydrocarbons, and hydrogen isotope combinations, thereby obtaining high-quality helium-3 gas. The mixed gas formed on the top layer during the storage of high-tritium heavy water can be fully utilized, thereby improving energy efficiency. At the same time, this application embodiment provides a new approach to obtaining helium-3, thereby increasing the yield of helium-3. Furthermore, the helium-3 extraction method of this application embodiment has the advantages of advanced process, high separation degree, and high-quality helium-3 gas. Attached Figure Description

[0033] Figure 1 This is a schematic flowchart of a method for extracting helium-3 from a high-tritium heavy water mixture according to an embodiment of this application;

[0034] Figure 2 This is a schematic flowchart illustrating a method for extracting helium-3 from a high-tritium heavy water mixture according to another embodiment of this application.

[0035] Figure 3 This is a schematic diagram of the structure of a helium-3 extraction system from a high-tritium heavy water mixture according to an embodiment of this application.

[0036] Explanation of reference numerals in the attached figures

[0037] 10. Purification unit; 11. Catalytic oxidation unit; 12. Low-temperature cooling unit; 13. Low-temperature adsorption unit; 20. Low-temperature pre-distillation unit; 30. Dehydrogenation unit; 31. Palladium membrane permeation unit; 32. Ultra-low temperature adsorption unit. Detailed Implementation

[0038] It should be noted that, unless otherwise specified, the embodiments and technical features in the embodiments of this application can be combined with each other, and the detailed descriptions in the specific implementation should be understood as explanations of the purpose of this application and should not be regarded as undue limitations on this application.

[0039] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0040] In related technologies, heavy water reactor nuclear power units use heavy water as a moderator and coolant. During reactor operation, deuterium in the heavy water absorbs neutrons and transforms into tritium (tritium in heavy water nuclear power units is mainly found in the moderator). Since the pressure tubes of heavy water reactor nuclear power units need to be replaced during their operational lifespan, and considering personnel radiation dose and environmental impact, the tritium-containing heavy water moderator needs to undergo detritium removal treatment before pressure tube replacement, thus obtaining a considerable amount of high-tritium heavy water. During storage, in addition to the formation of helium-3 due to tritium decay, the high-tritium heavy water also generates a certain amount of hydrogen isotope gas and oxygen due to the radiodecomposition effect of tritium. From a hydrogen safety perspective, a covering gas needs to be added to the cavity of the high-tritium heavy water storage container. The helium-3 produced by tritium decay mixes with the covering gas, forming a mixed gas, thus providing an alternative source of helium-3 gas.

[0041] Based on this, such as Figure 1 As shown, one embodiment of this application provides a method for extracting helium-3 from a high-tritium heavy water mixture.

[0042] It should be noted that heavy water is a compound composed of deuterium and oxygen, also known as deuterium oxide, with the molecular formula D2O.

[0043] There are three common isotopes of hydrogen in nature: protium (symbol H), deuterium (symbol D), and tritium (symbol T).

[0044] When heavy water is irradiated, deuterium absorbs neutrons to generate tritium, thus forming high-tritium heavy water.

[0045] The mixed gas is formed on top of the high-tritium heavy water. The mixed gas includes a covering gas, which is nitrogen (N2), that is, nitrogen is located in the cavity at the top of the high-tritium heavy water storage container.

[0046] Nitrogen is an inert gas and generally does not react with other substances. Using nitrogen as a cover gas makes it easier to separate nitrogen from helium-3 compared to using helium-4 as a cover gas in heavy water reactors.

[0047] Understandably, during the storage of high-tritium heavy water, the mixed gas includes not only nitrogen (N2) used as a covering gas, but also helium-3, water, water vapor, and trace amounts of hydrocarbons (C2) introduced from the nitrogen used as a covering gas. x H y In addition to O2, H2, and CO2, it also includes a certain amount of O2 and D2 (DT, HD, HT) generated by the radiative decomposition of water by tritium.

[0048] Specifically, methods for extracting helium-3 from the top layer mixture of high-tritium heavy water include:

[0049] S100 Purification Treatment: The mixed gas containing helium-3 is purified to remove water, water vapor, CO2, hydrocarbons, some N2, some O2, and some hydrogen isotope combination gas from the mixed gas and obtain the first stage crude helium gas.

[0050] Hydrogen isotope combination gases include HD, HT, H2, D2, and DT.

[0051] S200, Low-temperature pre-distillation treatment: The first-stage crude helium gas is subjected to low-temperature pre-distillation treatment to remove residual N2 and O2 in the first-stage crude helium gas and obtain the second-stage crude helium gas.

[0052] Specifically, by utilizing the difference in boiling points of different gases, the first-stage crude helium gas is cooled and liquefied under high pressure. The residual N2 and O2 in the first-stage crude helium gas can be liquefied at low temperature, thereby achieving the purpose of separation from the first-stage crude helium gas.

[0053] It is understandable that obtaining high pressure is easier than obtaining ultra-low temperature. Compared to atmospheric pressure, N2 and O2 have higher boiling points under high pressure, making them easier to liquefy.

[0054] After low-temperature pre-distillation, all heavy components relative to helium-3 in the first-stage crude helium gas can be reduced to below 1 ppm (parts per million). At this point, the second-stage crude helium gas obtained has a high concentration of helium-3.

[0055] The cryogenic pre-distillation process has unique advantages such as large throughput, high separation factor, and continuous operation. Therefore, in the embodiments of this application, the production of helium-3 can be increased, while the quality of the obtained helium-3 gas can be improved.

[0056] S300, Dehydrogenation treatment: The second-stage crude helium gas is dehydrogenated to remove the residual hydrogen isotope combination gas in the second-stage crude helium gas.

[0057] Understandably, the second-stage crude helium gas obtained after step S200 can reduce all heavy component gases relative to helium-3 to below 1 ppm, but it cannot remove light component gases such as hydrogen isotope combination gases.

[0058] By performing a dehydrogenation process, trace amounts of hydrogen isotope combinations remaining in the crude helium gas from the second stage can be removed, thus obtaining high-quality helium-3 gas with a purity ≥99.9999%, an abundance ≥99.96%, and impurity component content less than 1 ppm, and tritium content ≤1.0 × 10⁻⁶. -11 %atom.

[0059] The method for extracting helium-3 from a high-tritium heavy water mixture according to this application embodiment uses nitrogen as a covering gas. During storage, a mixed gas formed by mixing the covering gas with helium-3 and other gases obtained from tritium decay is used as raw material. The mixed gas undergoes purification, low-temperature pre-distillation, and dehydrogenation treatments in sequence to gradually remove water, water vapor, CO2, N2, O2, hydrocarbons, and hydrogen isotope combinations, thereby obtaining high-quality helium-3 gas. The mixed gas formed on the top layer during the storage of high-tritium heavy water can be fully utilized, thereby improving energy efficiency. At the same time, this application embodiment provides a new approach to obtaining helium-3, thereby increasing the yield of helium-3. Furthermore, the helium-3 extraction method of this application embodiment has the advantages of advanced process, high separation degree, and high-quality helium-3 gas.

[0060] In some embodiments, the low-temperature pre-distillation process specifically includes:

[0061] At liquid nitrogen temperature, the crude helium gas in the first stage is pre-distilled at low temperature using adsorption packing.

[0062] The adsorption packing can adsorb the target substance and, using the principle of low-temperature distillation, can thoroughly separate and remove the heavy components (equivalent to helium-3) in the first-stage crude helium gas, thereby obtaining the second-stage crude helium gas.

[0063] Understandably, the second-stage crude helium gas includes a light component of helium-3 gas and a hydrogen isotope combination gas containing trace amounts of tritium.

[0064] It should be noted that the type of adsorption packing is not limited. For example, in some embodiments, the adsorption packing includes at least one of metal triangular spiral packing and θ-ring packing.

[0065] In other words, the adsorption packing can be entirely made of metal triangular spiral packing, entirely made of θ-ring packing, or a combination of metal triangular spiral packing and θ-ring packing.

[0066] Of course, the adsorption packing material can also be other packing materials with the same properties.

[0067] Metal triangular spiral packing has advantages such as resistance to cold and heat, large porosity, large throughput, low pressure drop, low resistance, good separation effect, and long service life. As such, it can effectively separate helium-3 gas and can be reused repeatedly, reducing the cost of obtaining helium-3 gas.

[0068] Theta ring packing, also known as Dixon packing, has a large specific surface area and tortuous flow channels, which can increase the gas-liquid phase mass transfer area and the uniformity of fluid distribution, thereby improving separation efficiency. Furthermore, the high porosity of theta ring packing reduces flow resistance, decreases fluid residence time within the packing, and lowers energy consumption, thus improving the extraction efficiency of helium-3 gas.

[0069] In some embodiments, the adsorption packing includes a metal triangular spiral packing, the material of which includes at least one of stainless steel and copper.

[0070] In some embodiments, the extraction method further includes the following steps prior to the low-temperature pre-distillation process:

[0071] The adsorption packing material is treated to make it hydrophilic.

[0072] By treating the adsorption packing material to be hydrophilic, the heat transfer, mass transfer, and separation effects in the low-temperature pre-distillation process can be enhanced, thereby better removing gases other than helium-3.

[0073] like Figure 2 As shown, in some embodiments, the purification process specifically includes:

[0074] S110, Catalytic oxidation treatment: A mixed gas containing helium-3 is subjected to catalytic oxidation treatment to remove trace amounts of hydrocarbons and some hydrogen isotope combination gases from the mixed gas and obtain a first mixture.

[0075] It should be noted that when nitrogen is used as the covering gas, trace amounts of hydrocarbons (C60) will be introduced into the covering gas itself. x H y Tritium heavy water contains O2, H2, and CO2. During storage, tritium also generates a certain amount of O2 and D2 (DT, HD, HT) due to the radiation decomposition of water by tritium.

[0076] Hydrocarbons and hydrogen isotope gases are both organic compounds that are easily catalytically oxidized. Therefore, hydrocarbons and most of the hydrogen isotope gases can be removed through catalytic oxidation.

[0077] S120. Low-temperature cooling treatment: The first mixture is subjected to low-temperature cooling treatment to remove water and some water vapor from the first mixture and obtain a second mixture.

[0078] It is understandable that the boiling point of water vapor differs greatly from that of other gases such as CO2 in the first mixture. Therefore, by using a low-temperature cooling process, water vapor can be easily liquefied and condensed with water in the first mixture in the form of mist to form larger droplets, which can then be removed.

[0079] S130, Low-temperature adsorption treatment: The second mixture is subjected to low-temperature adsorption treatment to remove CO2, part of N2 and part of O2, as well as residual water vapor and obtain the first stage crude helium gas.

[0080] like Figure 2 As shown, in some embodiments, the catalytic oxidation treatment step specifically includes:

[0081] Under high temperature conditions, a mixed gas is controlled to be introduced into copper oxide so that the copper oxide reacts with the hydrocarbon and hydrogen isotope combination gas in the mixed gas to produce a redox reaction.

[0082] Copper oxide has strong reducing properties. After the hydrogen isotope gas and hydrocarbons undergo redox reactions with copper oxide, the hydrogen isotope gas is converted into water or water vapor, and the hydrocarbons are converted into CO2 and H2O. The water, water vapor and CO2 can be removed by subsequent low-temperature cooling and low-temperature adsorption treatment steps.

[0083] In other words, through the catalytic oxidation process, hydrocarbons and hydrogen isotope combinations that are difficult to remove can be converted into substances that are easier to remove, thereby reducing the difficulty of obtaining high-quality helium-3 gas.

[0084] In some embodiments, the cryogenic cooling process specifically includes:

[0085] The first mixture is controlled to flow through chilled water for low-temperature cooling.

[0086] In other words, the cold source in the low-temperature cooling step is chilled water. The temperature of the chilled water can be between -10℃ and -5℃, which can improve the liquefaction efficiency of water vapor.

[0087] In some embodiments, the low-temperature adsorption treatment step specifically includes:

[0088] At liquid nitrogen temperature, the second mixture is adsorbed at low temperature using a low-temperature adsorption material.

[0089] Specifically, liquid nitrogen can reach temperatures below -196°C, allowing CO2, N2, O2, and residual water vapor after the cryogenic cooling process to be effectively absorbed by the cryogenic adsorption material.

[0090] It should be noted that the type of low-temperature adsorption material is not limited. For example, in some embodiments, the low-temperature adsorption material includes at least one of molecular sieves and activated carbon.

[0091] In other words, low-temperature adsorption materials can be entirely molecular sieves, entirely activated carbon, or a combination of molecular sieves and activated carbon.

[0092] For example, molecular sieves are used for low-temperature adsorption. Small molecules can pass through the molecular sieve, thereby removing CO2 and water vapor. At the same time, due to the low-temperature adsorption process at liquid nitrogen temperature, the molecular sieve can also filter out a portion of N2 and O2.

[0093] like Figure 2 As shown, in some embodiments, the dehydrogenation treatment step specifically includes:

[0094] S310, Palladium membrane permeation treatment: The second-stage crude helium gas is subjected to palladium membrane permeation treatment to remove some of the hydrogen isotope combination gas in the second-stage crude helium gas and obtain the third-stage crude helium gas.

[0095] Specifically, in the second stage, the hydrogen isotope combination gas in the crude helium gas can permeate to the other side of the palladium membrane, while the helium-3 gas has difficulty passing through the palladium membrane. In this way, most of the hydrogen isotope combination gas can be removed.

[0096] S320, Cryogenic Adsorption Treatment: The crude helium gas in the third stage is subjected to cryogenic adsorption treatment to remove the residual hydrogen isotope combination gas in the crude helium gas in the third stage.

[0097] To improve the quality of helium-3 gas, trace amounts of hydrogen isotope compounds may still be present in the third-stage crude helium gas obtained after palladium membrane permeation treatment. Ultra-low temperature adsorption treatment can further remove these trace hydrogen isotope compounds, thereby improving the quality of the helium-3 gas.

[0098] In some embodiments, the palladium membrane permeation treatment step specifically includes:

[0099] A measured amount of hydrogen gas is added to the crude helium gas in the second stage;

[0100] Palladium membrane permeation was performed on the second-stage crude helium gas containing a measured amount of hydrogen to remove some of the hydrogen isotope combination gas from the second-stage crude helium gas.

[0101] It should be noted that the added hydrogen gas is H2. In this way, the gas pressure on both sides of the palladium membrane can be balanced during the palladium membrane permeation treatment step, so that the trace tritium and hydrogen-containing hydrogen isotope combination gas in the second stage crude helium gas can pass through the palladium membrane and permeate to the other side of the palladium membrane for removal.

[0102] It is understandable that a certain amount of hydrogen added to the second-stage crude helium gas will remain in the third-stage crude helium gas. Through the ultra-low temperature adsorption treatment step, the residual trace hydrogen in the third-stage crude helium gas can be removed, thus finally obtaining high-quality helium-3 gas.

[0103] In some embodiments, the cryogenic adsorption treatment step specifically includes:

[0104] Under conditions below 0.1K, cryogenic adsorption materials were used to adsorb crude helium gas in the third stage at cryogenic temperatures.

[0105] A temperature below 0.1K means a temperature below -273.05℃, which is close to the temperature of liquid helium. Under this condition, the residual trace amounts of hydrogen in the crude helium gas from the third stage can be largely removed, while helium-3 gas is retained, thus improving the quality of the final helium-3 gas.

[0106] Another aspect of this application provides a system for extracting helium-3 from a high-tritium heavy water mixture. This helium-3 extraction system is applicable to the helium-3 extraction method of any of the above embodiments.

[0107] like Figure 3 As shown, the extraction system includes a purification unit 10, a low-temperature pre-distillation unit 20, and a dehydrogenation unit 30.

[0108] The purification unit 10 includes a catalytic oxidation unit 11, a low-temperature cooling unit 12, and a low-temperature adsorption unit 13.

[0109] The catalytic oxidation treatment unit 11 is used to perform catalytic oxidation treatment on a mixed gas containing helium-3 to remove trace amounts of hydrocarbons and some hydrogen isotope combination gases from the mixed gas and obtain a first mixture.

[0110] Specifically, the catalytic oxidation unit can be a catalytic oxidation column containing copper oxide. A mixed gas containing helium-3 passes through the catalytic oxidation column, and at high temperature, the copper oxide reacts with hydrocarbons (C6H4O3, C ... x H y The combination of hydrocarbons (C) and hydrogen isotopes in the gas undergoes a redox reaction, thereby removing hydrocarbons (C) from the gas mixture. x H y The mixture of gases and hydrogen isotope combinations (H2, D2, HD, DT, HT) becomes the first mixture after passing through a catalytic oxidation column.

[0111] The low-temperature cooling unit 12 is used to perform low-temperature cooling on the first mixture to remove water and some water vapor from the first mixture and obtain a second mixture.

[0112] Specifically, the low-temperature cooling unit 12 can be a low-temperature condenser, in which chilled water flows. The temperature of the chilled water can be between -10℃ and -5℃. In this way, the water and water vapor in the first mixture can be condensed and separated and removed. After passing through the low-temperature condenser, the first mixture becomes the second mixture.

[0113] The low-temperature adsorption treatment unit 13 is used to perform low-temperature adsorption treatment on the second mixture to remove CO2, part of N2, part of O2 and residual water vapor from the second mixture and obtain the first stage crude helium gas.

[0114] Specifically, the low-temperature adsorption treatment unit 13 can be a low-temperature adsorber or a low-temperature adsorption column. For example, the low-temperature adsorption treatment unit 13 is a low-temperature adsorber, which is filled with at least one of molecular sieve and activated carbon. Using the principle of low-temperature adsorption, water vapor and part of N2, O2 and CO2 in the second mixture are further separated and removed. After the second mixture is separated of this part of the gas, it becomes the first stage crude helium gas.

[0115] The low-temperature pre-distillation unit 20 is used to perform low-temperature pre-distillation on the first-stage crude helium gas to remove residual N2 and O2 from the first-stage crude helium gas and obtain the second-stage crude helium gas.

[0116] Specifically, the cryogenic pre-distillation unit 20 can be a cryogenic pre-distillation column, which is filled with adsorption packing. At liquid nitrogen temperature, using the principle of cryogenic distillation, the heavy components (relative to helium-3) contained in the first-stage crude helium gas are removed more thoroughly, and the second-stage crude helium gas can be obtained at the top of the cryogenic pre-distillation column.

[0117] Understandably, the second-stage crude helium gas includes a light component of helium-3 gas and a hydrogen isotope combination gas containing trace amounts of tritium.

[0118] The adsorption packing material can be hydrophilicized to enhance the heat transfer, mass transfer and separation effects in the low-temperature pre-distillation process.

[0119] It should be noted that the type of adsorption packing is not limited. For example, it can be at least one of metal triangular spiral packing and θ-ring packing.

[0120] When the adsorption packing includes metal triangular spiral packing, the material of the metal triangular spiral packing includes at least one of stainless steel and copper.

[0121] It should be noted that the heavy component (relative to helium-3) in the second stage of crude helium gas is below 1 ppm.

[0122] The dehydrogenation treatment unit 30 includes a palladium membrane permeation treatment unit 31 and an ultra-low temperature adsorption treatment unit 32.

[0123] The palladium membrane permeation treatment unit 31 is used to perform palladium membrane permeation treatment on the second-stage crude helium gas to remove some of the hydrogen isotope combination gas in the second-stage crude helium gas and obtain the third-stage crude helium gas.

[0124] Specifically, the type of palladium membrane permeation treatment unit 31 is not limited. For example, it can be a self-supporting palladium membrane or a supported palladium membrane.

[0125] A certain amount of hydrogen is added to the second-stage crude helium gas at the top of the low-temperature pre-distillation column to maintain the gas pressure balance during palladium membrane permeation treatment. The palladium membrane permeation treatment unit 31 can separate and remove trace amounts of tritium and hydrogen-containing hydrogen isotope combination gases from the second-stage crude helium gas.

[0126] The cryogenic adsorption treatment unit 32 is used to perform cryogenic adsorption treatment on the crude helium gas in the third stage to remove the residual hydrogen isotope combination gas in the crude helium gas in the third stage.

[0127] Specifically, the cryogenic adsorption treatment unit 32 can be a cryogenic adsorption column, which is filled with cryogenic adsorption material. Under conditions where the temperature is below 0.1K, the cryogenic adsorption material separates and removes the residual trace amount of hydrogen in the crude helium gas of the third stage, thereby obtaining high-quality helium-3 gas.

[0128] The helium-3 extraction system of this application ultimately obtains helium-3 gas with a purity ≥99.9999%, an abundance ≥99.96%, and an impurity content of less than 1 ppm, with a tritium content ≤1.0 × 10⁻⁶. -11 %atom.

[0129] In the description of this application, the references to terms such as "in one embodiment," "in some embodiments," "in other embodiments," "in yet another embodiment," or "exemplary," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine the different embodiments or examples described in this application, as well as the features of the different embodiments or examples.

[0130] The above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the protection scope of this application.

Claims

1. A method for extracting helium-3 from a high-tritium heavy water mixture, wherein the mixture includes a covering gas, the covering gas being nitrogen, characterized in that... The extraction method includes: Catalytic oxidation treatment: The mixed gas containing helium-3 is subjected to catalytic oxidation treatment to remove trace amounts of hydrocarbons and some hydrogen isotope combination gases from the mixed gas and obtain a first mixture; Low-temperature cooling treatment: The first mixture is subjected to low-temperature cooling treatment to remove water and some water vapor from the first mixture and obtain a second mixture; Low-temperature adsorption treatment: The second mixture is subjected to low-temperature adsorption treatment to remove CO2, part of N2, part of O2 and residual water vapor from the second mixture and obtain the first stage crude helium gas; Low-temperature pre-distillation treatment: The first-stage crude helium gas is subjected to low-temperature pre-distillation treatment to remove residual N2 and O2 in the first-stage crude helium gas and obtain the second-stage crude helium gas; Dehydrogenation treatment: The crude helium gas in the second stage is subjected to dehydrogenation treatment to remove the residual hydrogen isotope combination gas in the crude helium gas in the second stage.

2. The extraction method according to claim 1, characterized in that, The catalytic oxidation treatment step specifically includes: Under high temperature conditions, the mixed gas is controlled to be introduced into copper oxide so that the copper oxide reacts with the hydrocarbon and hydrogen isotope combination gas in the mixed gas to produce a redox reaction.

3. The extraction method according to claim 1, characterized in that, The aforementioned low-temperature cooling process specifically includes: The first mixture is controlled to flow through chilled water for low-temperature cooling.

4. The extraction method according to claim 1, characterized in that, The aforementioned low-temperature adsorption treatment step specifically includes: The second mixture is adsorbed at low temperature using a low-temperature adsorption material at liquid nitrogen temperature.

5. The extraction method according to claim 4, characterized in that, The low-temperature adsorption material includes at least one of molecular sieve and activated carbon.

6. The extraction method according to any one of claims 1-5, characterized in that, The dehydrogenation process specifically includes: Palladium membrane permeation treatment: The second-stage crude helium gas is subjected to palladium membrane permeation treatment to remove some of the hydrogen isotope combination gas in the second-stage crude helium gas and obtain the third-stage crude helium gas; Cryogenic adsorption treatment: The crude helium gas in the third stage is subjected to cryogenic adsorption treatment to remove the residual hydrogen isotope combination gas in the crude helium gas in the third stage.

7. The extraction method according to claim 6, characterized in that, The palladium membrane permeation treatment step specifically includes: A measured amount of hydrogen gas is added to the crude helium gas in the second stage; The second-stage crude helium gas, to which a measured amount of hydrogen gas has been added, is permeated through a palladium membrane to remove some of the hydrogen isotope combination gas from the second-stage crude helium gas.

8. The extraction method according to claim 6, characterized in that, The aforementioned cryogenic adsorption treatment step specifically includes: Under conditions below 0.1K, the crude helium gas of the third stage is adsorbed at ultra-low temperatures using ultra-low temperature adsorption materials.

9. A system for extracting helium-3 from a high-tritium heavy water mixture, applicable to the method for extracting helium-3 from a high-tritium heavy water mixture according to any one of claims 1-8, the extraction system comprising: The purification unit includes a catalytic oxidation unit, a cryogenic cooling unit, and a cryogenic adsorption unit. The catalytic oxidation unit is used to catalytically oxidize the mixed gas containing helium-3 to remove trace amounts of hydrocarbons and some hydrogen isotope combinations to obtain a first mixture. The cryogenic cooling unit is used to cryogenically cool the first mixture to remove water and some water vapor to obtain a second mixture. The cryogenic adsorption unit is used to cryogenically adsorb the second mixture to remove CO2, some N2, some O2, and residual water vapor to obtain the first-stage crude helium gas. The low-temperature pre-distillation unit is used to perform low-temperature pre-distillation on the first-stage crude helium gas to remove residual N2 and O2 from the first-stage crude helium gas and obtain the second-stage crude helium gas. The dehydrogenation treatment unit includes a palladium membrane permeation treatment unit and an ultra-low temperature adsorption treatment unit. The palladium membrane permeation treatment unit is used to perform palladium membrane permeation treatment on the second stage crude helium gas to remove part of the hydrogen isotope combination gas in the second stage crude helium gas and obtain the third stage crude helium gas. The cryogenic adsorption treatment unit is used to perform cryogenic adsorption treatment on the third-stage crude helium gas to remove the residual hydrogen isotope combination gas in the third-stage crude helium gas.

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