Helium-3 and Helium-4 co-production system

Abstract

This utility model relates to the field of isotope separation technology, specifically to a co-production system for helium-3 and helium-4. The co-production system includes: a helium-4 liquefaction and circulation unit, a helium-3 enrichment unit, and a helium-3 purification unit. Helium-rich natural gas enters the helium-4 liquefaction and circulation unit from a helium storage tank and is liquefied to obtain liquid helium. The liquid helium contains 10% helium-3. ‑6 Liquid helium is enriched in a helium-3 enrichment unit, increasing the helium-3 content to 10. ‑3 -10 ‑2 The helium-3 is then purified and stored in a helium-3 storage tank after passing through a helium-3 purification unit, achieving a helium-3 content of 99.9%. The remaining helium-4 in the helium-3 enrichment unit and the helium-3 purification unit enters the helium-4 liquefaction and recycling unit.

Description

Technical Field

[0001] This utility model relates to the field of isotope separation technology, specifically to a co-production system for helium-3 and helium-4. Background Technology

[0002] Helium-3, a rare isotope of helium, is an irreplaceable working fluid for devices such as mK-level dilution refrigerators and clean nuclear fusion reactors. It is an indispensable strategic material for ensuring the development of quantum computers and the long-term secure acquisition of fusion energy in my country. Currently, my country is entirely dependent on imports for helium-3. However, since 2015, the United States has ceased official sales of helium-3, significantly impacting my country's helium-3 supply. Therefore, researching domestically produced industrial-scale helium-3 enrichment methods and equipment is crucial. Currently, the known sources of helium-3 are mainly three: tritium beta decay, helium-rich natural gas, and lunar soil. High helium-3 content has been found in some offshore natural gas fields in my country, possessing industrial extraction value. Crude helium is purified through liquefaction to obtain liquid helium, which is then further purified to produce helium-3. Separating helium-3 from liquid helium requires temperatures below the superfluid conversion temperature (2.17 K). Separating helium-3 from natural gas would require a large amount of energy for cooling the helium-3, and the economic costs of liquefaction and separation infrastructure and equipment would be high. Utility Model Content

[0003] To address the shortcomings of existing technologies, this invention provides a co-production system for helium-3 and helium-4, aiming to solve the problems of high energy requirements for separating helium-3 from natural gas, cooling helium-3, and the high economic costs of liquefaction and separation infrastructure and equipment.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a co-production system for helium-3 and helium-4, comprising: a helium-4 liquefaction and circulation unit, a helium-3 enrichment unit, and a helium-3 purification unit. Helium-rich natural gas enters the helium-4 liquefaction and circulation unit from a helium storage tank and is liquefied to obtain liquid helium, wherein the liquid helium contains 10% helium-3. -6 Liquid helium is enriched in the helium-3 enrichment unit, increasing the helium-3 content to 10. -3 -10 -2 The helium-3 is then purified and stored in the helium-3 storage tank after passing through the helium-3 purification unit, with a helium-3 content of 99.9%. The remaining helium-4 in the helium-3 enrichment unit and the helium-3 purification unit enters the helium-4 liquefaction and circulation unit. The helium-4 liquefaction cycle unit has a helium inlet, a liquid helium outlet, and a helium-4 recovery inlet; The helium-3 enrichment unit has its inlet connected to the liquid helium outlet of the helium-4 liquefaction circulation unit, and has an outlet for outputting enriched liquid helium and a first outlet for discharging the remaining helium-4. The helium-3 purification unit has its inlet connected to the outlet of the helium-3 enrichment unit for outputting enriched liquid helium, and has an outlet for outputting high-purity helium-3 and a second outlet for discharging the remaining helium-4. Both the first outlet and the second outlet are connected to the helium-4 recovery inlet of the helium-4 liquefaction circulation unit (1) via pipelines.

[0005] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit includes one of the following: Claude cycle structure, Collins cycle structure and dual-pressure cycle structure.

[0006] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit includes a compressor. When the remaining helium-4 in the helium-3 enrichment unit and the helium-3 purification unit is discharged as gas, it is discharged into a low-pressure pipeline through a third pipeline and a fifth pipeline, respectively. After passing through the compressor, it re-enters the liquefaction cycle for liquefaction. The third pipeline and the fifth pipeline are respectively equipped with a third shut-off valve and a fifth shut-off valve.

[0007] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction and circulation unit further includes a liquid helium dewar. When the remaining helium-4 in the helium-3 enrichment unit and the helium-3 purification unit is discharged as liquid, it flows into the liquid pipeline through the second pipeline and the fourth pipeline respectively, and enters the liquid helium dewar for storage through the liquid pipeline. The second pipeline is equipped with a first shut-off valve, and the liquid pipeline is equipped with a second shut-off valve and a fourth shut-off valve.

[0008] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit includes: a primary heat exchanger and a liquid nitrogen storage tank, wherein the primary heat exchanger is connected to the liquid nitrogen storage tank and a first valve is provided between the liquid nitrogen storage tank and the primary heat exchanger; the helium storage tank is connected to the primary heat exchanger through a first pipeline and a second valve is provided between the helium storage tank and the primary heat exchanger; in the primary heat exchanger, helium-rich natural gas and liquid nitrogen exchange heat, and the helium temperature at the outlet of the primary heat exchanger is 75-85K; the compressor outlet is connected to the first pipeline.

[0009] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit further includes: a secondary heat exchanger and a primary purifier, wherein the secondary heat exchanger is connected to the primary purifier and a third valve and a fourth valve are provided between the secondary heat exchanger and the primary purifier, and the secondary heat exchanger is connected to the primary heat exchanger.

[0010] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit further includes: a three-stage heat exchanger, a four-stage heat exchanger and a five-stage heat exchanger, the first-stage purifier is connected to the three-stage heat exchanger, the three-stage heat exchanger, the four-stage heat exchanger and the five-stage heat exchanger are connected in sequence, and the main helium gas enters the three-stage heat exchanger, the four-stage heat exchanger and the five-stage heat exchanger in sequence.

[0011] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit further includes: a secondary purifier, the secondary purifier being connected to the fifth-stage heat exchanger, and a sixth valve and a seventh valve being provided between the fifth-stage heat exchanger and the secondary purifier.

[0012] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit further includes: a six-stage heat exchanger, the six-stage heat exchanger being connected to the two-stage purifier, the six-stage heat exchanger being connected to the liquid helium Dewar and a throttling valve being provided between the six-stage heat exchanger and the liquid helium Dewar, the six-stage heat exchanger being connected to the helium-3 enrichment unit and the throttling valve and a ninth valve being provided between the six-stage heat exchanger and the helium-3 enrichment unit, and the helium gas loop escaping from the liquid helium Dewar sequentially enters the six-stage heat exchanger, the five-stage heat exchanger, the four-stage heat exchanger, the three-stage heat exchanger, the two-stage heat exchanger and the one-stage heat exchanger to form a helium gas loop, exchanging heat with the main helium gas.

[0013] According to the helium-3 and helium-4 co-production system provided by this utility model, the helium-4 liquefaction cycle unit further includes: a primary turbine expander and a secondary turbine expander. The primary turbine expander is connected to the primary purifier, and a fifth valve is provided between the primary turbine expander and the primary purifier. The primary turbine expander is connected to the fourth-stage heat exchanger, and the secondary turbine expander is connected to the fourth-stage heat exchanger. The helium loop between the secondary turbine expander and the sixth-stage and fifth-stage heat exchangers is connected. The branch helium passes through the primary turbine expander, the fourth-stage heat exchanger, and the secondary turbine expander in sequence before merging with the helium loop.

[0014] The beneficial effects of the helium-3 and helium-4 co-production system described in this utility model are as follows: The co-production system of helium-3 and helium-4 has economic advantages. Crude helium is liquefied and purified to obtain liquid helium, which is then further purified into helium-3. Separating helium-3 from liquid helium requires operating below the superfluid conversion temperature of helium-4 (2.17 K). If the process of separating helium-3 from natural gas is carried out simultaneously with the process of extracting helium-4 from natural gas, after helium-4 liquefaction, only 1°C remains before helium-3 liquefaction. Most of the energy required for cooling, as well as the cost of the liquefaction and separation infrastructure and equipment, is already included in the cost of helium-4 extraction. By adding a terminal cryogenic helium-3 enrichment unit and a helium-3 purification unit, the enrichment, concentration, and purification of helium-3 in helium-4 can be achieved. The helium-4 discharged from the helium-3 enrichment and purification units is then recycled back into the helium-4 liquefaction cycle unit for helium recovery. Purifying helium-3 after helium extraction enables large-scale extraction of helium-3 at a lower cost. The main economic cost of the process lies in the helium-4 liquefaction recycling unit, which includes the helium extraction and liquefaction portion of helium-rich natural gas. The helium-3 enrichment and purification units have lower costs, significantly reducing the overall cost of helium-3 extraction. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the helium-3 and helium-4 co-production system according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the specific structure of the helium-3 and helium-4 co-production system according to an embodiment of the present invention.

[0017] Figure 3 This is a first enlarged view of helium-3 and helium-4 according to an embodiment of this utility model.

[0018] Figure 4 This is a second enlarged view of helium-3 and helium-4 according to an embodiment of this utility model.

[0019] Explanation of reference numerals in the attached figures: 1. Helium-4 liquefaction and circulation unit; 2. Helium-3 enrichment unit; 3. Helium-3 purification unit; 11. First valve; 12. Second valve; 13. Third valve; 14. Fourth valve; 15. Fifth valve; 16. Sixth valve; 17. Seventh valve; 18. Throttling valve; 19. Ninth valve; 20. First shut-off valve; 21. Second shut-off valve; 22. Third shut-off valve; 23. Fourth shut-off valve; 24. Fifth shut-off valve; 25. Sixth shut-off valve; 31. Compressor; 32. First-stage turboexpander; 33. Second-stage turboexpander; 41. First-stage heat exchanger; 42. Second-stage heat exchanger; 43. Third-stage heat exchanger; 44. Fourth-stage heat exchanger; 45. Fifth-stage heat exchanger; 46. Sixth-stage heat exchanger; 51. First pipeline; 52. Second pipeline; 53. Third pipeline; 54. Fourth pipeline; 55. Fifth pipeline. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0021] The following is combined with Figure 1-4 This invention describes a co-production system for helium-3 and helium-4, comprising: a helium-4 liquefaction and recycling unit 1, a helium-3 enrichment unit 2, and a helium-3 purification unit 3. Helium-rich natural gas enters the helium-4 liquefaction and recycling unit 1 from a helium storage tank for liquefaction to obtain liquid helium, wherein the liquid helium contains 10% helium-3. -6 Liquid helium is enriched in helium-3 enrichment unit 2, increasing the helium-3 content to 10. -3 -10 -2 The helium-3 is then purified and stored in the helium-3 storage tank after passing through the helium-3 purification unit 3, with a helium-3 content of 99.9%. The remaining helium-4 in the helium-3 enrichment unit 2 and the helium-3 purification unit 3 enters the helium-4 liquefaction recycling unit 1. The co-production system of helium-3 and helium-4 has economic advantages. Crude helium is liquefied and purified to obtain liquid helium, which is then further purified into helium-3. Separating helium-3 from liquid helium requires operating below the superfluid conversion temperature of helium-4 (2.17 K). If the process of separating helium-3 from natural gas is carried out simultaneously with the process of extracting helium-4 from natural gas, after helium-4 liquefaction, only 1°C remains before helium-3 liquefaction. Most of the energy required for cooling, as well as the cost of the liquefaction and separation infrastructure and equipment, is already included in the cost of helium-4 extraction. By adding a terminal cryogenic helium-3 enrichment unit 2 and a helium-3 purification unit 3, the enrichment, concentration, and purification of helium-3 in helium-4 can be achieved. The helium-4 discharged from the helium-3 enrichment and purification units is then reintroduced into the helium-4 liquefaction cycle unit 1 for helium recovery. Purifying helium-3 after helium extraction enables large-scale extraction of helium-3 at a lower cost. The main economic cost of the process is in helium-4 liquefaction recycling unit 1, which is the helium extraction part from helium-rich natural gas and the helium liquefaction part. Helium-3 enrichment unit 2 and helium-3 purification unit 3 have lower costs, which greatly reduces the overall cost of helium-3 extraction.

[0022] In one feasible embodiment of this utility model, such as Figure 2 As shown, the helium-4 liquefaction cycle unit 1 includes one of the following: Claude cycle structure, Collins cycle structure, and dual-pressure cycle structure.

[0023] In one feasible embodiment of this utility model, such as Figure 2 As shown, the helium-4 liquefaction cycle unit 1 includes: a compressor 31. When the remaining helium-4 in the helium-3 enrichment unit 2 and the helium-3 purification unit 3 is discharged as a gas, it is discharged into the low-pressure pipeline through the third pipeline 53 and the fifth pipeline 55 respectively. After passing through the compressor 31, it re-enters the liquefaction cycle for liquefaction. The third pipeline 53 and the fifth pipeline 55 are respectively equipped with a third shut-off valve 22 and a fifth shut-off valve 24.

[0024] In one feasible embodiment of this utility model, such as Figure 2 As shown, the helium-4 liquefaction and circulation unit 1 also includes a liquid helium dewar. When the remaining helium-4 in the helium-3 enrichment unit 2 and the helium-3 purification unit 3 is discharged as a liquid, it flows into the liquid pipeline through the second pipeline 52 and the fourth pipeline 54 respectively, and enters the liquid helium dewar for storage through the liquid pipeline. The second pipeline 52 is equipped with a first shut-off valve 20, and the liquid pipeline is equipped with a second shut-off valve 21 and a fourth shut-off valve 23.

[0025] After passing through throttle valve 18, liquid helium is obtained, which is a mixture of helium-3 and helium-4, with a helium-3 content of approximately 10%. -6 Part of the helium is stored in a liquid helium Dewar (the flow rate of helium-3 processed by the helium-3 enrichment and purification unit is less than that of the helium-4 liquefaction unit), while the other part enters the helium-3 enrichment unit 2 through pipes and valves, enriching the helium-3 concentration by 1000-10000 times, with a helium-3 content of approximately 10. -3 -10 -2 The helium-3 continues to enter the helium-3 purification unit 3, where the helium-3 purity is as high as 99.9%. It is stored in a helium-3 storage tank, which is connected to the helium-3 purification unit 3 and a sixth shut-off valve 25 is installed between the helium-3 storage tank and the helium-3 purification unit 3.

[0026] In one feasible embodiment of this utility model, such as Figure 2 As shown, the helium-4 liquefaction cycle unit 1 includes: a primary heat exchanger 41 and a liquid nitrogen storage tank, wherein the primary heat exchanger 41 is connected to the liquid nitrogen storage tank and a first valve 11 is provided between the liquid nitrogen storage tank and the primary heat exchanger 41; a helium storage tank is connected to the primary heat exchanger 41 through a first pipeline 51 and a second valve 12 is provided between the helium storage tank and the primary heat exchanger 41; in the primary heat exchanger 41, helium-rich natural gas and liquid nitrogen exchange heat, and the helium temperature at the outlet of the primary heat exchanger 41 is 75-85K; the outlet of the compressor 31 is connected to the first pipeline 51.

[0027] In one feasible embodiment of this utility model, such as Figure 2As shown, the Helium-4 liquefaction cycle unit 1 also includes: a secondary heat exchanger 42 and a primary purifier. The secondary heat exchanger 42 is connected to the primary purifier, and a third valve 13 and a fourth valve 14 are provided between the secondary heat exchanger 42 and the primary purifier. The secondary heat exchanger 42 is connected to the primary heat exchanger 41.

[0028] The helium-rich natural gas passes through the secondary heat exchanger 42 and the primary purifier, which mainly remove impurities such as nitrogen and oxygen from the helium gas.

[0029] In one feasible embodiment of this utility model, such as Figure 2 As shown, the helium-4 liquefaction cycle unit 1 also includes: a third-stage heat exchanger 43, a fourth-stage heat exchanger 44, and a fifth-stage heat exchanger 45. The first-stage purifier is connected to the third-stage heat exchanger 43. The third-stage heat exchanger 43, the fourth-stage heat exchanger 44, and the fifth-stage heat exchanger 45 are connected in sequence. The main helium gas enters the third-stage heat exchanger 43, the fourth-stage heat exchanger 44, and the fifth-stage heat exchanger 45 in sequence.

[0030] In one feasible embodiment of this utility model, such as Figure 2 As shown, the Helium-4 liquefaction cycle unit 1 also includes a secondary purifier, which is connected to the fifth-stage heat exchanger 45, and a sixth valve 16 and a seventh valve 17 are provided between the fifth-stage heat exchanger 45 and the secondary purifier.

[0031] The main helium gas passes through the third-stage heat exchanger 43, the fourth-stage heat exchanger 44, and the fifth-stage heat exchanger 45 before entering the second-stage purifier, which mainly removes neon and hydrogen impurities from the helium gas.

[0032] In one feasible embodiment of this utility model, such as Figure 2 As shown, the Helium-4 liquefaction cycle unit 1 also includes: a sixth-stage heat exchanger 46, which is connected to the second-stage purifier, a liquid helium dewar, and a throttling valve 18 between the sixth-stage heat exchanger 46 and the liquid helium dewar; a sixth-stage heat exchanger 46 is connected to the Helium-3 enrichment unit 2, and a throttling valve 18 and a ninth valve 19 are provided between the sixth-stage heat exchanger 46 and the Helium-3 enrichment unit 2; the helium gas loop escaping from the liquid helium dewar sequentially enters the sixth-stage heat exchanger 46, the fifth-stage heat exchanger 45, the fourth-stage heat exchanger 44, the third-stage heat exchanger 43, the second-stage heat exchanger 42, and the first-stage heat exchanger 41 to form a helium gas loop, which exchanges heat with the main helium gas.

[0033] The main helium gas enters the sixth-stage heat exchanger 46, and after passing through the throttle valve 18, it becomes liquid helium, a mixture of helium-3 and helium-4, with a helium-3 content of approximately 10%. -6 .

[0034] In one feasible embodiment of this utility model, such as Figure 2As shown, the Helium-4 liquefaction cycle unit 1 also includes: a first-stage turbine expander 32 and a second-stage turbine expander 33. The first-stage turbine expander 32 is connected to the first-stage purifier and a fifth valve 15 is provided between the first-stage turbine expander 32 and the first-stage purifier. The first-stage turbine expander 32 is connected to the fourth-stage heat exchanger 44. The second-stage turbine expander 33 is connected to the fourth-stage heat exchanger 44. The helium circuit between the second-stage turbine expander 33 and the sixth-stage heat exchanger 46 and the fifth-stage heat exchanger 45 is connected. The branch helium passes through the first-stage turbine expander 32, the fourth-stage heat exchanger 44 and the second-stage turbine expander 33 in sequence and then merges with the helium circuit.

[0035] A portion of the helium enters the branch circuits of the first-stage turbine expander 32 and the second-stage turbine expander 33 for cooling and depressurization. The temperature of the helium at the outlet of the second-stage turbine expander 33 is approximately 11K, which merges with the helium loop escaping from the liquid helium Dewar.

[0036] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A co-production system of helium-3 and helium-4, characterized by, include: Helium-4 liquefaction cycle unit (1) has a helium inlet, a liquid helium outlet, and a helium-4 recovery inlet; The helium-3 enrichment unit (2) has its inlet connected to the liquid helium outlet of the helium-4 liquefaction circulation unit (1), and has an outlet for outputting enriched liquid helium and a first outlet for discharging the remaining helium-4. The helium-3 purification unit (3) has its inlet connected to the outlet of the helium-3 enrichment unit (2) for outputting enriched liquid helium, and has an outlet for outputting high-purity helium-3 and a second outlet for discharging the remaining helium-4. Both the first outlet and the second outlet are connected to the helium-4 recovery inlet of the helium-4 liquefaction circulation unit (1) via pipelines.

2. The co-production system of helium-3 and helium-4 of claim 1, wherein, The helium-4 liquefaction cycle unit (1) includes one of the following: Claude cycle structure, Collins cycle structure and dual-pressure cycle structure.

3. The co-production system of helium-3 and helium-4 of claim 2, wherein, The helium-4 liquefaction cycle unit (1) includes a compressor (31). When the remaining helium-4 in the helium-3 enrichment unit (2) and the helium-3 purification unit (3) is discharged as gas, it is discharged into the low-pressure pipeline through the third pipeline (53) and the fifth pipeline (55) respectively. After passing through the compressor (31), it re-enters the liquefaction cycle for liquefaction. The third pipeline (53) and the fifth pipeline (55) are respectively equipped with a third shut-off valve (22) and a fifth shut-off valve (24).

4. The co-production system of helium-3 and helium-4 of claim 3, wherein, The helium-4 liquefaction circulation unit (1) further includes a liquid helium dewar. When the remaining helium-4 in the helium-3 enrichment unit (2) and the helium-3 purification unit (3) is discharged as liquid, it flows into the liquid pipeline through the second pipeline (52) and the fourth pipeline (54) respectively, and enters the liquid helium dewar for storage through the liquid pipeline. The second pipeline (52) is equipped with a first shut-off valve (20), and the liquid pipeline is equipped with a second shut-off valve (21) and a fourth shut-off valve (23).

5. The co-production system of helium-3 and helium-4 according to claim 4, wherein, The helium-4 liquefaction cycle unit (1) includes: a primary heat exchanger (41) and a liquid nitrogen storage tank, wherein the primary heat exchanger (41) is connected to the liquid nitrogen storage tank and a first valve (11) is provided between the liquid nitrogen storage tank and the primary heat exchanger (41); the helium storage tank is connected to the primary heat exchanger (41) through a fifth pipe (55) and a second valve (12) is provided between the helium storage tank and the primary heat exchanger (41); in the primary heat exchanger (41), helium-rich natural gas and liquid nitrogen exchange heat, and the helium temperature at the outlet of the primary heat exchanger (41) is 75-85K; the outlet of the compressor (31) is connected to the fifth pipe (55).

6. The co-production system of helium-3 and helium-4 according to claim 5, wherein, The helium-4 liquefaction cycle unit (1) further includes: a secondary heat exchanger (42) and a primary purifier, wherein the secondary heat exchanger (42) is connected to the primary purifier and a third valve (13) and a fourth valve (14) are provided between the secondary heat exchanger (42) and the primary purifier, and the secondary heat exchanger (42) is connected to the primary heat exchanger (41).

7. The co-production system of helium-3 and helium-4 according to claim 6, wherein, The helium-4 liquefaction cycle unit (1) further includes a three-stage heat exchanger (43), a four-stage heat exchanger (44), and a five-stage heat exchanger (45). The first-stage purifier is connected to the three-stage heat exchanger (43). The three-stage heat exchanger (43), the four-stage heat exchanger (44), and the five-stage heat exchanger (45) are connected in sequence. The main helium gas enters the three-stage heat exchanger (43), the four-stage heat exchanger (44), and the five-stage heat exchanger (45) in sequence.

8. The co-production system of helium-3 and helium-4 of claim 7, wherein, The helium-4 liquefaction cycle unit (1) further includes a secondary purifier, which is connected to the fifth-stage heat exchanger (45) and a sixth valve (16) and a seventh valve (17) are provided between the fifth-stage heat exchanger (45) and the secondary purifier.

9. The co-production system of Helium-3 and Helium-4 according to claim 8, characterized in that, The helium-4 liquefaction circulation unit (1) further includes: a six-stage heat exchanger (46), which is connected to the secondary purifier, and is connected to the liquid helium Dewar. A throttling valve (18) is provided between the six-stage heat exchanger (46) and the liquid helium Dewar. The six-stage heat exchanger (46) is connected to the helium-3 enrichment unit (2), and the throttling valve (18) and the ninth valve (19) are provided between the six-stage heat exchanger (46) and the helium-3 enrichment unit (2). The helium gas loop escaping from the liquid helium Dewar sequentially enters the six-stage heat exchanger (46), the five-stage heat exchanger (45), the four-stage heat exchanger (44), the three-stage heat exchanger (43), the secondary heat exchanger (42), and the primary heat exchanger (41) to form a helium gas loop and exchange heat with the main helium gas.

10. The co-production system of helium-3 and helium-4 of claim 9, wherein, The helium-4 liquefaction cycle unit (1) further includes: a first-stage turbine expander (32) and a second-stage turbine expander (33). The first-stage turbine expander (32) is connected to the first-stage purifier and a fifth valve (15) is provided between the first-stage turbine expander (32) and the first-stage purifier. The first-stage turbine expander (32) is connected to the fourth-stage heat exchanger (44). The second-stage turbine expander (33) is connected to the fourth-stage heat exchanger (44). The second-stage turbine expander (33) is connected to the helium circuit between the sixth-stage heat exchanger (46) and the fifth-stage heat exchanger (45). The branch helium passes through the first-stage turbine expander (32), the fourth-stage heat exchanger (44), and the second-stage turbine expander (33) in sequence and then merges with the helium circuit.

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