Coproduction system of helium-3 and helium-4

Abstract

The invention relates to the technical field of isotope separation, in particular to a helium-3 and helium-4 co-production system which comprises a helium-4 liquefaction circulation unit, a helium-3 enrichment unit and a helium-3 purification unit, helium-rich natural gas enters the helium-4 liquefaction circulation unit from a helium storage tank to be liquefied, liquid helium is obtained, and the helium-rich natural gas enters the helium-4 liquefaction circulation unit to be liquefied, the content of helium-3 in the liquid helium is 10-6%; liquid helium is enriched through the helium-3 enrichment unit, and the helium-3 content is increased to 10 <-3 >-10 <-2 >; purifying by a helium-3 purification unit, and storing in a helium-3 storage tank, wherein the helium-3 content reaches 99.9%; and the residual helium-4 in the helium-3 enrichment unit and the helium-3 purification unit enters the helium-4 liquefaction circulation unit.

Description

Technical Field

[0001] The present invention relates to the technical field of isotope separation, and particularly relates to a co-production system for helium-3 and helium-4. Background Art

[0002] Helium-3 is a rare isotope of helium and is an irreplaceable working medium for devices such as mK-level dilution refrigerators and clean nuclear fusion. It is a strategic material essential for ensuring the development of China's quantum computers and obtaining long-term safe fusion energy. At present, China's helium-3 completely relies on imports. However, after 2015, the United States no longer sells helium-3 at the official level, which has a great impact on China's helium-3 supply. Therefore, it is crucial to study domestic industrial helium-3 enrichment methods and equipment. Currently, there are mainly three known sources of helium-3: tritium beta decay, helium-rich natural gas, and lunar soil. China has discovered that the helium-3 content in some helium-rich natural gas fields in certain regions is relatively high and has industrial extraction value. The crude helium gas is purified by liquefaction to obtain liquid helium, and then helium-3 purification continues. Separating helium-3 from liquid helium needs to be carried out below the superfluid transition temperature (2.17K). If separating helium-3 from natural gas, a large amount of energy is required for helium-3 cooling, and the economic costs of the infrastructure and equipment for liquefaction and separation are high. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a co-production system for helium-3 and helium-4, aiming to solve the problems of a large amount of energy required for cooling helium-3 when separating helium-3 from natural gas, and the high economic costs of the infrastructure and equipment for liquefaction and separation.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention provides a co-production system for helium-3 and helium-4, including: a helium-4 liquefaction cycle unit, a helium-3 enrichment unit, and a helium-3 purification unit. The helium-rich natural gas enters the helium-4 liquefaction cycle unit from the helium storage tank for liquefaction to obtain liquid helium, wherein the helium-3 content in the liquid helium is 10 -6 ; the liquid helium is enriched through the helium-3 enrichment unit to increase the helium-3 content to 10 -3 -10 -2 ; and then it is purified through the helium-3 purification unit and stored in the helium-3 storage tank, and the helium-3 content reaches 99.9%; the remaining helium-4 in the helium-3 enrichment unit and the helium-3 purification unit enters the helium-4 liquefaction cycle unit.

[0006] According to the co-production system for helium-3 and helium-4 provided by the present invention, the helium-4 liquefaction cycle unit includes one of a Claude cycle structure, a Collins cycle structure, and a dual-pressure cycle structure.

[0007] According to the co-production system of helium-3 and helium-4 provided by the present invention, the helium-4 liquefaction cycle unit includes: a compressor. When the remaining helium-4 discharged from the helium-3 enrichment unit and the helium-3 purification unit is in a gaseous state, they are respectively introduced into a low-pressure pipeline through a third pipeline and a fifth pipeline, and after passing through the compressor, they enter the liquefaction cycle again for liquefaction. A third stop valve and a fifth stop valve are respectively provided on the third pipeline and the fifth pipeline.

[0008] According to the co-production system of helium-3 and helium-4 provided by the present invention, the helium-4 liquefaction cycle unit further includes: a liquid helium dewar. When the remaining helium-4 discharged from the helium-3 enrichment unit and the helium-3 purification unit is in a liquid state, they are respectively introduced into a liquid pipeline through a second pipeline and a fourth pipeline, and enter the liquid helium dewar for storage through the liquid pipeline. A first stop valve is provided on the second pipeline, and a second stop valve and a fourth stop valve are provided on the liquid pipeline.

[0009] According to the co-production system of helium-3 and helium-4 provided by the present invention, the helium-4 liquefaction cycle unit includes: a primary heat exchanger and a liquid nitrogen storage tank. 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 gas storage tank is connected to the primary heat exchanger through a first pipeline, and a second valve is provided between the helium gas storage tank and the primary heat exchanger; in the primary heat exchanger, rich helium natural gas exchanges heat with liquid nitrogen, and the helium gas temperature at the outlet of the primary heat exchanger is 75 - 85K; the outlet of the compressor is connected to the first pipeline.

[0010] According to the co-production system of helium-3 and helium-4 provided by the present invention, the helium-4 liquefaction cycle unit further includes: a secondary heat exchanger and a primary purifier. 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. The secondary heat exchanger is connected to the primary heat exchanger.

[0011] According to the co-production system of helium-3 and helium-4 provided by the present invention, the helium-4 liquefaction cycle unit further includes: a tertiary heat exchanger, a quaternary heat exchanger and a quinary heat exchanger. The primary purifier is connected to the tertiary heat exchanger, and the tertiary heat exchanger, the quaternary heat exchanger and the quinary heat exchanger are sequentially connected. The main path helium gas sequentially enters the tertiary heat exchanger, the quaternary heat exchanger and the quinary heat exchanger.

[0012] According to the co-production system of helium-3 and helium-4 provided by the present invention, the helium-4 liquefaction cycle unit further includes: a secondary purifier. The secondary purifier is connected to the quinary heat exchanger, and a sixth valve and a seventh valve are provided between the quinary heat exchanger and the secondary purifier.

[0013] According to the helium-3 and helium-4 co-production system provided by the present invention, the helium-4 liquefaction cycle unit further includes: a six-stage heat exchanger, which is connected to the secondary purifier, and is connected to the liquid helium dewar, and a throttle valve is provided between the six-stage heat exchanger and the liquid helium dewar. The six-stage heat exchanger is connected to the helium-3 enrichment unit, and a throttle valve and a ninth valve are provided between the six-stage heat exchanger and the helium-3 enrichment unit. The helium gas circuit 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 circuit, which exchanges heat with the main path helium gas.

[0014] According to the helium-3 and helium-4 co-production system provided by the present invention, the helium-4 liquefaction cycle unit further includes: a first-stage turbine expander and a second-stage turbine expander. The first-stage turbine expander is connected to the first-stage purifier, and a fifth valve is provided between the first-stage turbine expander and the first-stage purifier. The first-stage turbine expander is connected to the four-stage heat exchanger. The second-stage turbine expander is connected to the four-stage heat exchanger, and the second-stage turbine expander is connected to the helium gas circuit between the six-stage heat exchanger and the five-stage heat exchanger. The branch helium gas sequentially passes through the first-stage turbine expander, the four-stage heat exchanger, and the second-stage turbine expander and then converges with the helium gas circuit.

[0015] The beneficial effects of a helium-3 and helium-4 co-production system described in the present invention are as follows:

[0016] The helium-3 and helium-4 co-production system has economic advantages. The crude helium gas is liquefied and purified to obtain liquid helium, and then helium-3 purification is continued. Separating helium-3 from liquid helium needs to be carried out below the superfluid transition temperature of helium-4 (2.17K). If the process of separating helium-3 from natural gas and the process of extracting helium-4 from natural gas are carried out simultaneously, after helium-4 is liquefied, there is only 1°C left until helium-3 is liquefied. Most of the energy required for cooling and most of the costs of the infrastructure and equipment for liquefaction and separation are already included in the extraction cost of helium-4. By adding an end ultra-low temperature 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 helium-3 purification devices re-enters the helium-4 liquefaction cycle unit for helium recovery. On the basis of helium extraction, helium-3 is further purified, and helium-3 can be extracted on a large scale at a relatively low cost. The main economic cost of the process is mainly in the helium-4 liquefaction cycle unit, that is, the part of helium extraction from rich helium natural gas and the part of helium liquefaction. The costs of the helium-3 enrichment unit and the helium-3 purification unit are relatively low, and overall, the helium-3 extraction cost is greatly reduced. Description of the Drawings

[0017] Figure 1It is a schematic structural diagram of a helium-3 and helium-4 co-production system according to an embodiment of the present invention.

[0018] Figure 2 It is a specific schematic structural diagram of a helium-3 and helium-4 co-production system according to an embodiment of the present invention.

[0019] Figure 3 It is the first enlarged view of helium-3 and helium-4 according to an embodiment of the present invention.

[0020] Figure 4 It is the second enlarged view of helium-3 and helium-4 according to an embodiment of the present invention.

[0021] Explanation of reference numerals:

[0022] 1. Helium-4 liquefaction cycle 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. Throttle valve; 19. Ninth valve; 20. First stop valve; 21. Second stop valve; 22. Third stop valve; 23. Fourth stop valve; 24. Fifth stop valve; 25. Sixth stop valve; 31. Compressor; 32. First-stage turbine expander; 33. Second-stage turbine expander; 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 manners

[0023] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts fall within the protection scope of the present invention.

[0024] The following combines Figures 1-4 Describe a helium-3 and helium-4 co-production system of the present invention, including: a helium-4 liquefaction cycle unit 1, a helium-3 enrichment unit 2 and a helium-3 purification unit 3. The helium-rich natural gas enters the helium-4 liquefaction cycle unit 1 from the helium storage tank for liquefaction to obtain liquid helium. Among them, the helium-3 content in the liquid helium is 10 -6 ; the liquid helium is enriched through the helium-3 enrichment unit 2 to increase the helium-3 content to 10 -3 -10 -2; It is then purified by the helium-3 purification unit 3 and stored in the helium-3 storage tank, and the helium-3 content reaches 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 circulation unit 1.

[0025] The helium-3 and helium-4 co-production system has economic advantages. Crude helium is purified by liquefaction, and helium-3 is further purified after obtaining liquid helium. The separation of helium-3 from liquid helium needs to be carried out below the superfluid transition temperature of helium-4 (2.17K). 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 is liquefied, it is only 1°C away from the liquefaction of helium-3. Most of the energy required for cooling and most of the cost of infrastructure and equipment for liquefaction and separation are already included in the extraction cost of helium-4. By adding the terminal ultra-low temperature helium-3 enrichment unit 2 and the helium-3 purification unit 3, the enrichment, concentration and purification of helium-3 in helium-4 can be achieved, and the discharged helium-4 in the helium-3 enrichment and helium-3 purification devices re-enters the helium-4 liquefaction circulation unit 1 for helium recovery. By purifying helium-3 on the basis of helium extraction, helium-3 can be extracted on a large scale at a relatively low cost. The main economic cost of the process is mainly in the helium-4 liquefaction circulation unit 1, that is, the helium extraction part and the helium liquefaction part in the helium-rich natural gas. The helium-3 enrichment unit 2 and the helium-3 purification unit 3 have relatively low costs, which greatly reduces the overall cost of helium-3 extraction.

[0026] In a feasible embodiment of the present invention, Figure 2 As shown, the helium-4 liquefaction cycle unit 1 includes: one of a Claude cycle structure, a Collins cycle structure and a dual-pressure cycle structure.

[0027] In a feasible embodiment of the present invention, Figure 2 As shown, the helium-4 liquefaction circulation unit 1 includes: a compressor 31. The remaining helium-4 in the helium-3 enrichment unit 2 and the helium-3 purification unit 3 is discharged as gas, and then passes through the third pipeline 53 and the fifth pipeline 55 to enter the low-pressure pipeline respectively, and enters the liquefaction cycle again for liquefaction after passing through the compressor 31. The third pipeline 53 and the fifth pipeline 55 are respectively provided with a third stop valve 22 and a fifth stop valve 24.

[0028] In a feasible embodiment of the present invention, Figure 2 As shown, the helium-4 liquefaction circulation unit 1 also includes: a liquid helium dewar. The remaining helium-4 in the helium-3 enrichment unit 2 and the helium-3 purification unit 3 is discharged as liquid, and then respectively flows into the liquid pipeline through the second pipeline 52 and the fourth pipeline 54, and enters the liquid helium dewar for storage from the liquid pipeline. The second pipeline 52 is provided with a first stop valve 20, and the liquid pipeline is provided with a second stop valve 21 and a fourth stop valve 23.

[0029] After passing through the throttle valve 18, liquid helium, i.e., a mixture of helium-3 and helium-4, is obtained, with the helium-3 content being approximately 10 -6 , a part of which enters the liquid helium dewar for storage (the flow rate of the helium-3 enrichment and purification device for processing helium-3 is less than that of the helium-4 liquefier), and the other part enters the helium-3 enrichment device of the helium-3 enrichment unit 2 through pipelines and valves, enriching the helium-3 concentration by 1000 - 10000 times, with the helium-3 content being approximately 10 -3 -10 -2 , and then continues to enter the helium-3 purification device of the helium-3 purification unit 3, with the helium-3 purity reaching as high as 99.9%, which is stored in the helium-3 storage tank. The helium-3 storage tank is connected to the helium-3 purification unit 3, and a sixth stop valve 25 is provided between the helium-3 storage tank and the helium-3 purification unit 3.

[0030] In a feasible embodiment of the present invention, as Figure 2 shown, the helium-4 liquefaction cycle unit 1 includes: a primary heat exchanger 41 and a liquid nitrogen storage tank. 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 gas 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 gas storage tank and the primary heat exchanger 41; in the primary heat exchanger 41, the helium-rich natural gas exchanges heat with liquid nitrogen, and the helium gas 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.

[0031] In a feasible embodiment of the present invention, as Figure 2 shown, the helium-4 liquefaction cycle unit 1 further 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.

[0032] The helium-rich natural gas passing through the secondary heat exchanger 42 and the primary purifier mainly serves to remove impurities such as nitrogen and oxygen in the helium gas.

[0033] In a feasible embodiment of the present invention, as Figure 2 shown, the helium-4 liquefaction cycle unit 1 further includes: a tertiary heat exchanger 43, a quaternary heat exchanger 44, and a quinary heat exchanger 45. The primary purifier is connected to the tertiary heat exchanger 43, and the tertiary heat exchanger 43, the quaternary heat exchanger 44, and the quinary heat exchanger 45 are connected in sequence. The main path helium gas enters the tertiary heat exchanger 43, the quaternary heat exchanger 44, and the quinary heat exchanger 45 in sequence.

[0034] In a feasible embodiment of the present invention, as Figure 2As shown, the helium-4 liquefaction cycle unit 1 further includes: a secondary purifier, which is connected to the fifth heat exchanger 45, and a sixth valve 16 and a seventh valve 17 are provided between the fifth heat exchanger 45 and the secondary purifier.

[0035] The helium gas in the main path enters the secondary purifier after passing through the third heat exchanger 43, the fourth heat exchanger 44, and the fifth heat exchanger 45, mainly removing neon and hydrogen impurities in the helium gas.

[0036] In a feasible embodiment of the present invention, as Figure 2 shown, the helium-4 liquefaction cycle unit 1 further includes: a sixth heat exchanger 46, which is connected to the secondary purifier, the sixth heat exchanger 46 is connected to the liquid helium dewar, and a throttle valve 18 is provided between the sixth heat exchanger 46 and the liquid helium dewar. The sixth heat exchanger 46 is connected to the helium-3 enrichment unit 2, and a throttle valve 18 and a ninth valve 19 are provided between the sixth heat exchanger 46 and the helium-3 enrichment unit 2. The helium gas circuit escaping from the liquid helium dewar sequentially enters the sixth heat exchanger 46, the fifth heat exchanger 45, the fourth heat exchanger 44, the third heat exchanger 43, the second heat exchanger 42, and the first heat exchanger 41 to form a helium gas circuit, and exchanges heat with the helium gas in the main path.

[0037] The helium gas in the main path enters the sixth heat exchanger 46, and after passing through the throttle valve 18, liquid helium is obtained, that is, a mixture of helium-3 and helium-4, and the helium-3 content is about 10 -6 .

[0038] In a feasible embodiment of the present invention, as Figure 2 shown, 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 purifier, and a fifth valve 15 is provided between the first-stage turbine expander 32 and the first purifier. The first-stage turbine expander 32 is connected to the fourth heat exchanger 44, the second-stage turbine expander 33 is connected to the fourth heat exchanger 44, and the second-stage turbine expander 33 is connected to the helium gas circuit between the sixth heat exchanger 46 and the fifth heat exchanger 45. The branch helium gas sequentially passes through the first-stage turbine expander 32, the fourth heat exchanger 44, and the second-stage turbine expander 33 and then converges with the helium gas circuit.

[0039] A part of the helium gas enters the branch of the first-stage turbine expander 32 and the second-stage turbine expander 33 for temperature reduction and pressure reduction. The temperature of the helium at the outlet of the second-stage turbine expander 33 is about 11K, and it converges with the helium gas circuit escaping from the liquid helium dewar.

[0040] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0041] 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 connection with the embodiment or mode are included in at least one embodiment or mode of the embodiments of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or modes. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or modes described in this specification and the features of different embodiments or modes.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. And these modifications or replacements 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 the present invention.

Claims

1. A helium-3 and helium-4 co-production system, characterized in that: include: A helium-4 liquefaction circulation unit (1), a helium-3 enrichment unit (2) and a helium-3 purification unit (3), wherein the helium-rich natural gas enters the helium-4 liquefaction circulation unit (1) from the helium storage tank for liquefaction to obtain liquid helium, wherein the helium-3 content in the liquid helium is 10 -6 ; Liquid helium is enriched by the helium-3 enrichment unit (2) to increase the helium-3 content to 10 -3 -10 -2 ; It is then purified by the helium-3 purification unit (3) and stored in a helium-3 storage tank, and the helium-3 content reaches 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 circulation unit (1).

2. The helium-3 and helium-4 co-production system according to claim 1, characterized in that: The helium-4 liquefaction cycle unit (1) comprises: one of a Claude cycle structure, a Collins cycle structure and a dual-pressure cycle structure.

3. The helium-3 and helium-4 co-production system according to claim 2, characterized in that: The helium-4 liquefaction circulation unit (1) comprises a compressor (31). When the residual helium-4 in the helium-3 enrichment unit (2) and the helium-3 purification unit (3) is discharged as gas, it is respectively introduced into a low-pressure pipeline through a third pipeline (53) and a fifth pipeline (55), and enters the liquefaction cycle again for liquefaction after passing through the compressor (31). The third pipeline (53) and the fifth pipeline (55) are respectively provided with a third stop valve (22) and a fifth stop valve (24).

4. The helium-3 and helium-4 co-production system according to claim 3, characterized in that: The helium-4 liquefaction circulation unit (1) further comprises: 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 is respectively fed into a liquid pipeline through a second pipeline (52) and a fourth pipeline (54), and enters the liquid helium dewar from the liquid pipeline for storage. The second pipeline (52) is provided with a first stop valve (20), and the liquid pipeline is provided with a second stop valve (21) and a fourth stop valve (23).

5. The helium-3 and helium-4 co-production system according to claim 4, characterized in that: The helium-4 liquefaction circulation unit (1) comprises: 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) via a fifth pipeline (51) and a second valve (12) is provided between the helium storage tank and the primary heat exchanger (41); helium-rich natural gas exchanges heat with liquid nitrogen in the primary heat exchanger (41), and the helium temperature at the outlet of the primary heat exchanger (41) is 75-85K; and the outlet of the compressor (31) is connected to the fifth pipeline (51).

6. The helium-3 and helium-4 co-production system according to claim 5, characterized in that: The helium-4 liquefaction circulation unit (1) further comprises: a secondary heat exchanger (42) and a primary purifier, wherein the secondary heat exchanger (42) is in communication with 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 in communication with the primary heat exchanger (41).

7. The helium-3 and helium-4 co-production system according to claim 6, characterized in that: The helium-4 liquefaction circulation unit (1) further comprises: 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; and 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.

8. The helium-3 and helium-4 co-production system according to claim 7, characterized in that: The helium-4 liquefaction circulation unit (1) further comprises: a secondary purifier, wherein the secondary purifier 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 helium-3 and helium-4 co-production system according to claim 8, characterized in that: The helium-4 liquefaction circulation unit (1) further comprises: a six-stage heat exchanger (46), the six-stage heat exchanger (46) being in communication with the two-stage purifier, the six-stage heat exchanger (46) being in communication with the liquid helium dewar, and a throttle valve (18) being arranged between the six-stage heat exchanger (46) and the liquid helium dewar, the six-stage heat exchanger (46) being in communication with the helium-3 enrichment unit (2), and the throttle valve (18) and a ninth valve (19) being arranged between the six-stage heat exchanger (46) and the helium-3 enrichment unit (2), and a helium loop escaping from the liquid helium dewar sequentially entering 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 two-stage heat exchanger (42) and the one-stage heat exchanger (41) to form a helium loop for heat exchange with the main helium.

10. The helium-3 and helium-4 co-production system according to claim 9, characterized in that: The helium-4 liquefaction circulation unit (1) further comprises: 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.

Images