A thermal purge gas extraction helium-3 enrichment system

Abstract

The utility model relates to a kind of hot flushing air exhaust helium-3 system, including primary heat exchanger, secondary heat exchanger, tertiary heat exchanger, refrigeration plant, helium-3 collection device, still including hot flushing component, the hot flushing component includes the heating unit of close connection in the bottom of the tertiary heat exchanger.The utility model is in the way of hot flushing and air exhaust separation combination, effectively promote the evaporation of helium-3 in solution, improve the recovery helium-3 abundance, while, increase the recovery rate of helium-3.

Description

Technical Field

[0001] This utility model relates to the field of gas separation technology, and in particular to a thermal flushing gas extraction system for enriching helium-3. Background Technology

[0002] Helium-3 can be used for dilution cooling, neutron detection, and other fields. Currently, there is no mature technology in China to obtain this gas. One of the main sources of helium-3 in China is nuclear shielding gas, in which the helium-3 abundance is 0.5%.

[0003] Existing enrichment techniques include cryogenic distillation, superleaking, and vacuum separation. Cryogenic distillation can theoretically achieve high-abundance helium-3 enrichment (90%), but its separation theory is complex, relevant databases are lacking, experimental setups are complex, and process control is difficult. Superleaking separation relies on a chemical potential equilibrium mechanism for helium-3 enrichment; however, this mechanism limits its ability to enrich helium-3 to above 30%. Thermal flushing separation, based on the two-fluid theory of superfluid helium, flushes helium-3 to the cryogenic end of the liquid to achieve enrichment; however, this method cannot remove the helium-3. The principle of the gas extraction and separation method is as follows: At low temperatures (below 4K), the vapor pressure of helium-3 is greater than that of helium-4. In the vapor of the helium-3 and helium-4 mixture, the abundance of helium-3 is higher than that in the solution. Taking out the vapor of the mixed solution can achieve enrichment of high abundance (above 95%) of helium-3. However, since the density of the vapor is much lower than that of the solution, most of the helium-3 still remains in the solution. Therefore, the overall recovery rate of helium-3 using this method is very low.

[0004] Therefore, existing technologies need to be improved. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a thermal flushing and pumping system for enriching helium-3, which aims to solve the problems of the inability to separate high-abundance helium-3.

[0006] The technical solution of this utility model is as follows: A thermal flushing extraction system for enriching helium-3 includes a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a refrigeration device, and a helium-3 collection device. It also includes a thermal flushing assembly, which includes a heating unit tightly connected to the bottom of the tertiary heat exchanger.

[0007] Optionally, to improve the heating effect, the heating unit includes one or more heating rods.

[0008] Optionally, the thermal flushing assembly also includes an outer casing that covers the heating unit and is fixed to the three-stage heat exchanger.

[0009] Optionally, the refrigeration device includes a vacuum outer casing, a refrigeration unit, and a primary cold head, a secondary cold head, and a tertiary cold head disposed within the vacuum outer casing and connected in sequence to the refrigeration unit; The first-stage heat exchanger is thermally connected to the first-stage cold head and is located inside the vacuum casing; the second-stage heat exchanger is thermally connected to the second-stage cold head and is located inside the vacuum casing; the third-stage heat exchanger is thermally connected to the third-stage cold head and is located inside the vacuum casing. The first-stage heat exchanger is provided with a first air inlet pipe and a first air outlet pipe, the second-stage heat exchanger is provided with a second air inlet pipe and a second air outlet pipe, and the third-stage heat exchanger is provided with a container; the container is provided with a liquid inlet and an air outlet, with the air outlet located at the upper end of the third-stage heat exchanger. The first inlet pipe is connected to the raw gas to be treated, and the first outlet pipe is connected to the helium-3 collection device. The first air inlet pipe and the second air inlet pipe, the second air inlet pipe and the liquid inlet, and the air outlet and the second air outlet pipe are connected by conduits.

[0010] In one embodiment, the primary cold head is connected to the primary heat exchanger via an indium sheet, the secondary cold head is connected to the secondary heat exchanger via an indium sheet, and the tertiary cold head is connected to the tertiary heat exchanger via an indium sheet. It should be noted that, to improve thermal conductivity, thermal grease should be applied to the surface of the indium sheet during use.

[0011] Beneficial effects: This invention effectively promotes the evaporation of helium-3 in the solution by combining thermal flushing and gas extraction separation, thereby increasing the abundance of recovered helium-3 and the recovery rate of helium-3. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of Example 1.

[0013] Figure 2 This is a schematic diagram of the structure of the thermal flushing component in Example 1. Detailed Implementation

[0014] This invention provides a continuously operating parallel helium-3 distillation system. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following provides a more detailed description. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this invention.

[0015] In the description of this utility model, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, in the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0016] Example 1 like Figure 1 , 2 As shown, the thermal flushing extraction system for enriching helium-3 in this embodiment includes a primary heat exchanger 1, a secondary heat exchanger 2, a tertiary heat exchanger 3, a refrigeration device 4, a helium-3 collection device 5, and a thermal flushing assembly 6, which includes a heating unit 6-1 tightly connected to the bottom of the tertiary heat exchanger 3.

[0017] It should be noted that, in order to enhance the heat transfer effect, the heating unit 6-1 should be tightly connected to the bottom of the three-stage heat exchanger 3. If there is a gap, an indium sheet and high thermal conductivity silicone grease should be installed.

[0018] Traditional gas extraction and separation efficiency depends on the abundance of helium-3 in the solution of the three-stage heat exchanger 3. As the amount of extracted gas increases, the helium-3 content in the solution continuously decreases, leading to a decrease in the helium-3 abundance in the extracted gas. This embodiment proposes using thermal flushing to flush helium-3 from the solution to the solution surface, thereby promoting the evaporation of helium-3 in the mixed solution, increasing the helium-3 abundance in the vapor during the gas extraction process, and improving both the helium-3 recovery efficiency and the helium-3 recovery rate. Therefore, this embodiment effectively promotes the evaporation of helium-3 in the solution and increases both the abundance and recovery rate of helium-3 by combining thermal flushing and gas extraction separation.

[0019] To improve heating efficiency, the heating unit 6-1 includes one or more heating rods. During the experiment, the diameter of the three-stage heat exchanger 3 is typically 60-70mm. In this embodiment, a single U-shaped heating rod is used. Since the three-stage heat exchanger 3 is made of copper, its thermal conductivity is excellent, so one U-shaped heating rod is sufficient. If the three-stage heat exchanger is larger, multiple spaced heating rods can be used.

[0020] The thermal flushing assembly 6 also includes an outer shell 6-2 that covers the heating unit 6-1 and is fixed to the three-stage heat exchanger 3.

[0021] It should be noted that the outer casing 6-2 and the three-stage heat exchanger 3 can be welded or riveted together. The outer casing 6-2 also has a through hole for the wires of the heating unit 6-1 to pass through. The outer casing 6-2 is made of a high thermal conductivity material to protect the heating unit 6-1; the heating unit 6-1 is used for heating and can contact the outer casing through an indium sheet and high thermal conductivity silicone grease to ensure effective heat transfer.

[0022] The refrigeration device 4 described in this embodiment includes a vacuum outer casing 4-5, a refrigeration unit 4-1, a primary cold head 4-2, a secondary cold head 4-3, and a tertiary cold head 4-4 disposed inside the vacuum outer casing 4-5 and connected in sequence to the refrigeration unit 4-1. The first-stage heat exchanger 1 is thermally connected to the first-stage cold head 4-2 and is located inside the vacuum outer casing 4-5; the second-stage heat exchanger 2 is thermally connected to the second-stage cold head 4-3 and is located inside the vacuum outer casing 4-5; and the third-stage heat exchanger 3 is thermally connected to the third-stage cold head 4-4 and is located inside the vacuum outer casing 4-5. The first-stage heat exchanger 1 is provided with a first air inlet pipe 1-1 and a first air outlet pipe 1-2. The second-stage heat exchanger 2 is provided with a second air inlet pipe 2-1 and a second air outlet pipe 2-2. The third-stage heat exchanger 3 is provided with a container 3-1. The container 3-1 is provided with a liquid inlet 3-2 and an air outlet 3-3. The air outlet 3-3 is located at the upper end of the third-stage heat exchanger 3. The first inlet pipe 1-1 is connected to the raw gas to be treated, and the first outlet pipe 1-2 is connected to the helium-3 collection device 5. The first air inlet pipe 1-1 and the second air inlet pipe 2-1, the second air inlet pipe 2-1 and the liquid inlet 3-2, and the air outlet 3-3 and the second air outlet pipe 2-2 are connected by conduits.

[0023] It should be noted that the primary heat exchanger 1 enables the gas entering the primary heat exchanger 1 to switch between 300K and 35K. The secondary heat exchanger 2 enables the gas entering the secondary heat exchanger 2 to switch between 35K and 4K; The three-stage heat exchanger 3 enables the gas entering the three-stage heat exchanger 3 to switch between 4K and 0.3~2K.

[0024] In this embodiment, the primary cold head 4-2 is connected to the primary heat exchanger 1 via an indium sheet, the secondary cold head 4-3 is connected to the secondary heat exchanger 2 via an indium sheet, and the tertiary cold head 4-4 is connected to the tertiary heat exchanger 3 via an indium sheet. It should be noted that, to increase thermal conductivity, thermal grease should be applied to the surface of the indium sheet during use.

[0025] It should be noted that the system is cooled by the refrigeration unit 4. The raw gas to be treated, with a low helium-3 abundance of approximately 0.5%, enters sequentially from the first inlet pipe 1-1 into the first-stage heat exchanger 1, the second-stage heat exchanger 2, and the third-stage heat exchanger 3, where it is converted into superfluid helium. Within the container 3-1 of the third-stage heat exchanger 3, the vapor pressure of helium-3 is much higher than that of helium-4. Therefore, the helium-3 content in the vapor within container 3-1 is greater than the helium-3 content in the solution. The gas is then extracted from the vapor, thus enriching helium-3. Experiments have shown that this scheme (without the thermal flushing component 6) can enrich helium-3 from approximately 0.5% abundance to 20% abundance. If the thermal flushing component 6 is included in this embodiment, the helium-3 abundance can be enriched from approximately 0.5% abundance to 70% abundance. Therefore, the combination of thermal flushing and gas extraction effectively promotes the evaporation of helium-3 in the solution, increasing both the abundance and recovery rate of helium-3.

[0026] It should be noted that the raw gas to be processed is a mixture of helium-3 and helium-4, and the abundance of helium-3 in the mixture is 0.2% to 2%, preferably 0.5%. For example, it is 0.2%, 0.5%, 0.7%, 0.9%, 1%, 1.5%, 1.7%, or 2%.

[0027] It should be understood that the application of this utility model is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A thermal flushing and extraction system for enriching helium-3, comprising a primary heat exchanger (1), a secondary heat exchanger (2), a tertiary heat exchanger (3), a refrigeration device (4), and a helium-3 collection device (5), characterized in that, It also includes a heat flushing assembly (6), which includes a heating unit (6-1) tightly connected to the bottom of the three-stage heat exchanger (3).

2. The thermal flushing and extraction system for enriching helium-3 according to claim 1, characterized in that, The heating unit (6-1) includes one or more heating rods.

3. The thermal flushing and extraction system for enriching helium-3 according to claim 2, characterized in that, The thermal flushing assembly (6) also includes an outer shell (6-2) that covers the heating unit (6-1) and is fixed to the three-stage heat exchanger (3).

4. The thermal flushing and extraction system for enriching helium-3 according to claim 1, characterized in that, The refrigeration device (4) includes a vacuum outer casing (4-5), a refrigeration unit (4-1), a primary cold head (4-2), a secondary cold head (4-3), and a tertiary cold head (4-4) located inside the vacuum outer casing (4-5) and connected in sequence to the refrigeration unit (4-1). The first-stage heat exchanger (1) is thermally connected to the first-stage cold head (4-2) and located inside the vacuum outer casing (4-5); the second-stage heat exchanger (2) is thermally connected to the second-stage cold head (4-3) and located inside the vacuum outer casing (4-5); and the third-stage heat exchanger (3) is thermally connected to the third-stage cold head (4-4) and located inside the vacuum outer casing (4-5). The first-stage heat exchanger (1) is provided with a first inlet pipe (1-1) and a first outlet pipe (1-2), the second-stage heat exchanger (2) is provided with a second inlet pipe (2-1) and a second outlet pipe (2-2), and the third-stage heat exchanger (3) is provided with a container (3-1); the container (3-1) is provided with a liquid inlet (3-2) and an outlet (3-3), and the outlet (3-3) is located at the upper end of the third-stage heat exchanger (3); The first inlet pipe (1-1) is connected to the raw gas to be treated, and the first outlet pipe (1-2) is connected to the helium-3 collection device (5); The first air inlet pipe (1-1) and the second air inlet pipe (2-1), the second air inlet pipe (2-1) and the liquid inlet (3-2), and the air outlet (3-3) and the second air outlet pipe (2-2) are connected by conduits.

5. A thermal flushing and extraction system for enriching helium-3 according to claim 4, characterized in that, The first-stage cold head (4-2) is connected to the first-stage heat exchanger (1) via an indium sheet, the second-stage cold head (4-3) is connected to the second-stage heat exchanger (2) via an indium sheet, and the third-stage cold head (4-4) is connected to the third-stage heat exchanger (3) via an indium sheet.

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