Helium liquefaction device and method

Abstract

Provided in the present invention are a helium liquefaction device and method. The helium liquefaction device comprises a helium circulation compressor unit, a heat exchange unit, and a first throttle valve, wherein an outlet of the helium circulation compressor unit is in communication with a high-pressure-side refrigeration helium inlet of the heat exchange unit, a high-pressure-side refrigeration helium outlet of the heat exchange unit is in communication with an inlet of the first throttle valve, an outlet of the first throttle valve is in communication with a low-pressure-side refrigeration helium inlet of the heat exchange unit, and a low-pressure-side refrigeration helium outlet of the heat exchange unit is in communication with an inlet of the helium circulation compressor unit to form a helium refrigeration circulation loop; and a helium-to-be-liquefied inlet and a liquid helium outlet of the heat exchange unit are respectively connected to a helium source and a liquid helium storage tank to form a helium liquefaction pipe. The present invention isolates a helium refrigeration cycle from the helium liquefaction pipe to prevent coupling, thereby preventing pressure changes in the liquid helium storage tank from affecting the helium refrigeration circulation loop, reducing the control difficulty of the helium liquefaction device, and improving the system stability and the feed gas liquefaction rate.

Description

A helium liquefaction apparatus and method Technical Field

[0001] This invention relates to the field of helium liquefaction technology, and in particular to a helium liquefaction apparatus and method. Background Technology

[0002] Helium is a colorless, odorless, non-toxic, and non-flammable inert gas at room temperature and normal pressure, and its chemical properties are extremely stable. Helium has a normal boiling point of -268.93℃ and a critical temperature of -267.96℃, making it the most difficult gas to liquefy. 1m 3 Liquid helium at 0℃ and 101.325 kPa is approximately 700.05 m³. 3 Helium. Therefore, liquid helium is also an important carrier for helium transportation. In addition, liquid helium, as a refrigerant, has important applications in aerospace technology, superconductivity, and cryogenic electronics.

[0003] Modern helium liquefaction systems mostly employ modified versions of the Claude cycle, typically using a two-stage expander followed by a single-stage throttling refrigeration system. This liquefaction process is a semi-open cycle, and its main disadvantages are as follows:

[0004] (1) The refrigeration cycle and the liquefied raw material circuit are connected, and the liquefaction rate of the raw material gas is low;

[0005] (2) The refrigeration cycle and the liquefied raw material circuit are coupled with each other, making the system control complex and difficult;

[0006] (3) Pressure changes in the liquid helium storage tank can affect the refrigeration cycle, thereby affecting system stability;

[0007] (4) The low inlet temperature of the first-stage expander results in a large amount of cold energy in the low-temperature zone being used to cool the raw gas and the helium in the refrigeration cycle at higher temperatures, resulting in a waste of cold energy.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome at least some of the shortcomings of the prior art and provide a helium liquefaction device. By setting the helium refrigeration cycle and the helium liquefaction pipeline as two completely independent pipelines, the two pipelines are isolated from each other to prevent coupling, avoid the pressure changes of the liquid helium storage tank from affecting the helium refrigeration cycle loop, reduce the control difficulty of the helium liquefaction device, and improve the system stability and the liquefaction rate of the raw material gas.

[0010] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0011] A helium liquefaction device includes: a helium circulating compressor unit, a heat exchanger unit, and a first throttling valve;

[0012] Wherein, the outlet of the helium circulation compressor unit is connected to the high-pressure side refrigeration helium inlet of the heat exchanger unit, the high-pressure side refrigeration helium outlet of the heat exchanger unit is connected to the inlet of the first throttle valve, the outlet of the first throttle valve is connected to the low-pressure side refrigeration helium inlet of the heat exchanger unit, and the low-pressure side refrigeration helium outlet of the heat exchanger unit is connected to the inlet of the helium circulation compressor unit to form a helium refrigeration circulation loop.

[0013] The heat exchanger unit's helium inlet and liquid helium outlet are connected to a helium source and a liquid helium storage tank, respectively, to form a helium liquefaction pipeline.

[0014] In some embodiments, the heat exchange unit includes a precooling heat exchange unit, a turbine heat exchange unit, and a final stage heat exchange unit connected in sequence.

[0015] The high-pressure side refrigeration helium inlet and low-pressure side refrigeration helium outlet of the pre-cooling heat exchange unit are respectively connected to the outlet and inlet of the helium circulation compressor unit, and the high-pressure side refrigeration helium outlet and low-pressure side refrigeration helium inlet of the final stage heat exchange unit are respectively connected to the inlet and outlet of the first throttle valve.

[0016] In some embodiments, the turbine heat exchange unit includes a plurality of cooling heat exchangers connected in sequence and a plurality of turbine expanders connected in series.

[0017] The precooling heat exchange unit has a first branch and a second branch at its high-pressure side refrigeration helium outlet. The first branch is connected to the high-pressure side refrigeration helium inlet of the plurality of cooling heat exchangers, and the second branch is connected to the high-pressure side refrigeration helium inlet of the plurality of turbine expanders. The high-pressure side refrigeration helium outlet of the plurality of cooling heat exchangers is connected to the high-pressure side refrigeration helium inlet of the final stage heat exchange unit, and the low-pressure side refrigeration helium outlet of the plurality of turbine expanders is connected to the low-pressure side refrigeration helium inlet of the plurality of cooling heat exchangers.

[0018] In some embodiments, the series piping of the plurality of turbine expanders is via at least one of the plurality of cooling heat exchangers.

[0019] In some embodiments, the precooling heat exchange unit includes a liquid nitrogen precooler, a first precooling heat exchanger, and a second precooling heat exchanger.

[0020] The liquid nitrogen precooler has a first heat exchange circuit and a second heat exchange circuit capable of heat exchange.

[0021] The two ends of the first heat exchange circuit are respectively connected to the liquid nitrogen source and the precooling working fluid inlet of the first precooling heat exchanger, and the two ends of the second heat exchange circuit are respectively connected to the precooling working fluid outlet of the first precooling heat exchanger and the precooling working fluid inlet of the second precooling heat exchanger.

[0022] In some embodiments, the precooling heat exchange unit further includes a third precooling heat exchanger;

[0023] The third precooling heat exchanger is disposed between the second precooling heat exchanger and the turbine heat exchange unit.

[0024] In some embodiments, the helium liquefaction pipeline is further provided with a second throttle valve and a third throttle valve;

[0025] The second throttle valve is located between the turbine heat exchange unit and the final stage heat exchange unit, and the third throttle valve is located downstream of the final stage heat exchange unit.

[0026] The present invention also provides a helium liquefaction method, employing the helium liquefaction apparatus according to the above description, comprising:

[0027] The refrigeration helium flows from the outlet of the helium cycle compressor unit to the heat exchange unit. After exchanging heat with the helium to be liquefied in the heat exchange unit, it is throttled and cooled by the first throttling valve and then flows back to the heat exchange unit and back to the helium cycle compressor unit, completing the helium refrigeration cycle loop.

[0028] Meanwhile, the helium to be liquefied exchanges heat with the cooled helium in the heat exchange unit and is cooled into liquid helium.

[0029] In some embodiments, the heat exchange unit includes a precooling heat exchange unit, a turbine heat exchange unit, and a final stage heat exchange unit connected in sequence.

[0030] In this process, the liquefied helium gas is cooled by the pre-cooling heat exchange unit and the turbine heat exchange unit and then undergoes the first throttling. After being cooled by the final heat exchange unit, it undergoes the second throttling and is converted into atmospheric pressure liquid helium.

[0031] In some embodiments, the turbine heat exchange unit includes a plurality of cooling heat exchangers connected in sequence and a plurality of turbine expanders connected in series, the series piping of the plurality of turbine expanders passing through at least one of the plurality of cooling heat exchangers;

[0032] After being expanded in the first-stage turbine expander of multiple turbine expanders, the refrigerated helium gas is cooled by at least one cooling heat exchanger before entering the remaining series turbine expanders for further expansion and cooling.

[0033] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0034] (1) The helium liquefaction device provided by the present invention sets the helium refrigeration cycle and the helium liquefaction pipeline as two completely independent pipelines, so that the two pipelines are isolated from each other, preventing coupling, avoiding the influence of pressure changes in the liquid helium storage tank on the helium refrigeration cycle loop, reducing the control difficulty of the helium liquefaction device, and improving system stability and raw material gas liquefaction rate.

[0035] (2) The helium liquefaction device provided by the present invention, when the refrigerated helium passes through multiple turbine expanders, after expanding through one of the first-stage turbine expanders, it first passes through at least one cooling heat exchanger to cool down before entering the remaining series turbine expanders for expansion and cooling. This helps to increase the inlet temperature of the refrigerated helium in the first-stage turbine expander, so that the cold energy of the expander can be used in a more appropriate temperature range, and the system energy consumption is lower.

[0036] (3) The helium liquefaction device provided by the present invention performs the first throttling after the liquefied helium gas is cooled by the pre-cooling heat exchange unit and the turbine heat exchange unit, and the raw material helium pressure is reduced to the preset value. After being cooled by the final heat exchange unit, it is throttled for the second time and converted into atmospheric pressure liquid helium. This ensures that the liquid helium after throttling by the last stage throttling valve is 100% liquid phase. Attached Figure Description

[0037] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0038] Figure 1 is a schematic flowchart of a helium liquefaction device according to an exemplary embodiment of the present invention.

[0039] In the diagram: 100, Helium liquefaction unit; 110, Helium cycle compressor unit; 120, Heat exchanger unit; 121, Pre-cooling heat exchange unit; 1211, Liquid nitrogen precooler; 1212, First pre-cooling heat exchanger; 1213, Second pre-cooling heat exchanger; 1214, Third pre-cooling heat exchanger; 122, Turbine heat exchange unit; 1221, First cooling heat exchanger; 1222, Second cooling heat exchanger; 1223, Third cooling heat exchanger; 1224, First turbine expander; 1225, Second turbine expander; 1226, Third turbine expander; 123, Final stage heat exchange unit; 130, First throttle valve; 140, Second throttle valve; 150, Third throttle valve;

[0040] 200. Helium refrigeration cycle loop;

[0041] 300. Helium liquefaction pipeline;

[0042] 400. Liquid nitrogen circulation loop.

[0043] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0045] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] As described in the background section, existing helium liquefaction systems suffer from low liquefaction rates of raw material gas, complex system control, and high difficulty. Based on this, the present invention provides a helium liquefaction device, comprising: a helium circulation compressor unit, a heat exchanger unit, and a first throttling valve; wherein, the outlet of the helium circulation compressor unit is connected to the high-pressure side refrigerated helium inlet of the heat exchanger unit, the high-pressure side refrigerated helium outlet of the heat exchanger unit is connected to the inlet of the first throttling valve, the outlet of the first throttling valve is connected to the low-pressure side refrigerated helium inlet of the heat exchanger unit, and the low-pressure side refrigerated helium outlet of the heat exchanger unit is connected to the inlet of the helium circulation compressor unit to form a helium refrigeration circulation loop; the helium inlet to be liquefied and the liquid helium outlet of the heat exchanger unit are respectively connected to a helium source and a liquid helium storage tank to form a helium liquefaction pipeline. In the above solution, by setting the helium refrigeration loop and the helium liquefaction pipeline as two completely independent pipelines, the two pipelines are isolated from each other, preventing coupling and avoiding the impact of pressure changes in the liquid helium storage tank on the helium refrigeration circulation loop, reducing the control difficulty of the helium liquefaction device, and improving system stability and raw material gas liquefaction rate.

[0048] The preferred technical solution of a helium liquefaction device and method provided by the present invention will be described in detail below with reference to Figure 1.

[0049] Figure 1 shows a schematic flow diagram of a helium liquefaction device 100 provided according to an exemplary embodiment of the present invention.

[0050] As shown in Figure 1, the helium liquefaction device 100 includes a helium circulation compressor unit 110, a heat exchanger unit 120, and a first throttle valve 130. The helium circulation compressor unit 110 converts the low-pressure side refrigerated helium in the helium refrigeration cycle loop 200 into high-pressure side refrigerated helium. The heat exchanger unit 120 uses the cooling capacity of the refrigerated helium to cool the helium to be liquefied, converting it into liquid helium with a certain pressure. The first throttle valve 130 converts the high-pressure refrigerated helium into low-pressure refrigerated helium.

[0051] Specifically, the outlet of the helium circulating compressor unit 110 is connected to the high-pressure side refrigeration helium inlet of the heat exchanger unit 120, the high-pressure side refrigeration helium outlet of the heat exchanger unit 120 is connected to the inlet of the first throttle valve 130, the outlet of the first throttle valve 130 is connected to the low-pressure side refrigeration helium inlet of the heat exchanger unit 120, and the low-pressure side refrigeration helium outlet of the heat exchanger unit 120 is connected to the inlet of the helium circulating compressor unit 110 to form a helium refrigeration loop 200; the helium inlet to be liquefied and the liquid helium outlet of the heat exchanger unit 120 are respectively connected to a helium source and a liquid helium storage tank to form a helium liquefaction pipeline 300.

[0052] In some embodiments, the heat exchange unit 120 includes a pre-cooling heat exchange unit 121, a turbine heat exchange unit 122, and a final-stage heat exchange unit 123 connected in sequence. The high-pressure side refrigerant helium inlet and the low-pressure side refrigerant helium outlet of the pre-cooling heat exchange unit 121 are respectively connected to the outlet and inlet of the helium circulation compressor unit 110, and the high-pressure side refrigerant helium outlet and the low-pressure side refrigerant helium inlet of the final-stage heat exchange unit 123 are respectively connected to the inlet and outlet of the first throttle valve 130.

[0053] It should be noted that the operating temperature ranges of the precooling heat exchange unit 121, the turbine heat exchange unit 122, and the final stage heat exchange unit 123 are different. As an example, the operating temperature range of the precooling heat exchange unit 121 and the turbine heat exchange unit 122 is above 20K, while the operating temperature range of the final stage heat exchange unit 123 is below 20K.

[0054] The helium liquefaction pipeline 300 is also provided with a second throttle valve 140 and a third throttle valve 150; wherein the second throttle valve 140 is located between the turbine heat exchange unit 122 and the final stage heat exchange unit 123, and the third throttle valve 150 is located downstream of the final stage heat exchange unit 123.

[0055] The turbine heat exchange unit 122 includes a plurality of cooling heat exchangers connected in sequence and a plurality of turbine expanders connected in series; wherein, the high-pressure side refrigeration helium outlet of the pre-cooling heat exchange unit 121 has a first branch and a second branch, the first branch is connected to the high-pressure side refrigeration helium inlet of the plurality of cooling heat exchangers, the second branch is connected to the high-pressure side refrigeration helium inlet of the plurality of turbine expanders, the high-pressure side refrigeration helium outlet of the plurality of cooling heat exchangers is connected to the high-pressure side refrigeration helium inlet of the final stage heat exchange unit 123, and the low-pressure side refrigeration helium outlet of the plurality of turbine expanders is connected to the low-pressure side refrigeration helium inlet of the plurality of cooling heat exchangers.

[0056] Referring to Figure 1, the helium liquefaction device 100 provided by the present invention operates as follows:

[0057] The high-pressure refrigerated helium gas at the outlet of the helium cycle compressor unit 110 flows to the pre-cooling heat exchange unit 121 through the high-pressure side refrigerated helium gas inlet. After pre-cooling the helium gas to be liquefied that also flows through the pre-cooling heat exchange unit 121, the high-pressure side refrigerated helium gas outlet of the pre-cooling heat exchange unit 121 splits into two branches. In the first branch, the high-pressure refrigerated helium gas passes through multiple cooling heat exchangers in sequence, cooling the helium gas to be liquefied that also flows through multiple cooling heat exchangers. Then, it enters the final heat exchange unit 123 to cool the helium gas to be liquefied that also flows through the final heat exchange unit 123. Finally, it enters the first throttling valve 130 for throttling and cooling before returning to the final heat exchange unit 123, providing cooling capacity near the liquid helium temperature range. In the second branch, the high-pressure refrigerated helium gas expands and cools after passing through a multi-stage series turbine expander. It then merges with the throttled low-pressure refrigerated helium gas returned from the final heat exchange unit 123. The gas then returns sequentially to multiple cooling heat exchangers and pre-cooling heat exchange units 121 to continue providing cooling for the helium gas to be liquefied before flowing back to the low-pressure inlet of the helium circulation compressor unit 110, completing the entire helium refrigeration cycle.

[0058] After being cooled by the pre-cooling heat exchange unit 121 and the turbine heat exchange unit 122, the liquefied helium gas undergoes a first throttling through the second throttling valve 140. After being cooled by the final stage heat exchange unit 123, it undergoes a second throttling through the third throttling valve 150, thus transforming into atmospheric pressure liquid helium.

[0059] It is important to explain here that the existing helium liquefaction process only throttles the high-pressure liquid helium through a throttling valve after the final heat exchange unit 123. The throttling temperature of the high-pressure liquid helium remains unchanged. Under otherwise identical conditions, the enthalpy of the high-pressure liquid helium is higher than that of the low-pressure liquid helium. Since throttling is an isenthalpic process, some liquid helium will vaporize after throttling (increasing the enthalpy) to maintain the overall enthalpy, thus preventing the raw material helium from being 100% liquefied. This invention adds a throttling valve before the final heat exchange unit 123 in the helium liquefaction pipeline 300. Here, the pressure of the high-pressure liquid helium is reduced to a certain value, ensuring that the high-pressure liquid helium, completely liquefied in the final heat exchange unit 123, does not need to undergo a vaporization process to achieve an isenthalpic process after passing through the third throttling valve 150. This results in the liquid helium after throttling through the third throttling valve 150 being 100% liquid, which helps to improve the liquefaction rate and purity of the liquid helium.

[0060] In some embodiments, the series piping of the plurality of turbine expanders passes through at least one of the plurality of cooling heat exchangers. This allows the refrigerant helium, after expanding in one of the turbine expanders, to be cooled by at least one cooling heat exchanger before entering the remaining series turbine expanders for further expansion and cooling. This helps to increase the inlet temperature of the refrigerant helium in the first-stage turbine expander, allowing the expander's cooling capacity to be used in a more appropriate temperature range, resulting in lower system energy consumption.

[0061] Specifically, the turbine heat exchange unit 122 includes a first cooling heat exchanger 1221, a second cooling heat exchanger 1222, and a third cooling heat exchanger 1223 connected in sequence, as well as a first turbine expander 1224, a second turbine expander 1225, and a third turbine expander 1226 connected in series. The high-pressure refrigerated helium in the first branch passes sequentially through the first cooling heat exchanger 1221, the second cooling heat exchanger 1222, and the third cooling heat exchanger 1223 to cool and lower the temperature of the helium to be liquefied, which also flows through these heat exchangers, before entering the final stage heat exchange unit 123. The high-pressure refrigerated helium in the second branch is expanded and refrigerated by the first turbine expander 1224, then passes through the second cooling heat exchanger 1222, and then through the second turbine expander 1225 and the third turbine expander 1226 connected in series. After that, it merges with the throttled low-pressure refrigerated helium returned from the final heat exchange unit 123 and enters the third cooling heat exchanger 1223.

[0062] In some embodiments, the precooling heat exchange unit 121 includes a liquid nitrogen precooler 1211, a first precooling heat exchanger 1212, and a second precooling heat exchanger 1213; wherein, the liquid nitrogen precooler 1211 has a first heat exchange loop and a second heat exchange loop capable of heat exchange; the two ends of the first heat exchange loop are respectively connected to a liquid nitrogen source and the precooling working fluid inlet of the first precooling heat exchanger 1212, and the two ends of the second heat exchange loop are respectively connected to the precooling working fluid outlet of the first precooling heat exchanger 1212 and the precooling working fluid inlet of the second precooling heat exchanger 1213.

[0063] Referring to Figure 1, the liquid nitrogen circulation loop 400 is as follows: Liquid nitrogen flowing out from the liquid nitrogen source enters the liquid nitrogen precooler 1211, passes through the first heat exchange loop, and then enters the first precooling heat exchanger 1212 through the precooling working fluid inlet to cool the refrigerated helium and the helium to be liquefied. After that, it flows out through the precooling working fluid outlet of the first precooling heat exchanger 1212 and returns to the second heat exchange loop of the liquid nitrogen precooler 1211 to absorb the coldness of the liquid nitrogen before flowing out. It then enters the second precooling heat exchanger 1213 through the precooling working fluid inlet to cool the refrigerated helium and the helium to be liquefied. Finally, it is converted into nitrogen and discharged through the precooling working fluid outlet of the second precooling heat exchanger 1213.

[0064] Furthermore, the precooling heat exchange unit 121 also includes a third precooling heat exchanger 1214; wherein the third precooling heat exchanger 1214 is disposed between the second precooling heat exchanger 1213 and the turbine heat exchange unit 122.

[0065] It should be noted that the number of precooling heat exchangers in the precooling heat exchange unit 121, the number of cooling heat exchangers in the turbine heat exchange unit 122, and the number of heat exchangers in the final stage heat exchange unit 123 can be set in different quantities as needed.

[0066] The present invention also provides a helium liquefaction method, employing the helium liquefaction device 100 described above, comprising: refrigerated helium gas flowing from the outlet of a helium gas circulation compressor unit 110 to a heat exchanger unit 120; after exchanging heat with the helium gas to be liquefied in the heat exchanger unit 120, the gas is throttled and cooled by a first throttling valve 130 and then flows back to the heat exchanger unit 120 and returns to the helium gas circulation compressor unit 110, completing the helium refrigeration cycle loop 200; simultaneously, the helium gas to be liquefied exchanges heat with the refrigerated helium gas in the heat exchanger unit 120 and is cooled into liquid helium.

[0067] In some embodiments, the heat exchange unit 120 includes a pre-cooling heat exchange unit 121, a turbine heat exchange unit 122, and a final heat exchange unit 123 connected in sequence; wherein, the helium gas to be liquefied is cooled by the pre-cooling heat exchange unit 121 and the turbine heat exchange unit 122 and then throttled for the first time, and then cooled by the final heat exchange unit and throttled for the second time, and is converted into atmospheric pressure liquid helium.

[0068] In some embodiments, the turbine heat exchange unit 122 includes a plurality of cooling heat exchangers connected in sequence and a plurality of turbine expanders connected in series, wherein the series pipeline of the plurality of turbine expanders passes through at least one of the plurality of cooling heat exchangers; after the refrigerated helium gas is expanded in the first-stage turbine expander of the plurality of turbine expanders, it is cooled by at least one cooling heat exchanger and then enters the remaining series turbine expanders of the plurality of turbine expanders for expansion and cooling.

[0069] It should be noted that the detailed process of the helium liquefaction method can be referred to the helium liquefaction device 100 described with reference to FIG1, and will not be repeated here.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A helium liquefier, characterized by, include: Helium cycle compressor unit, heat exchanger unit, and first throttle valve; Wherein, the outlet of the helium circulation compressor unit is connected to the high-pressure side refrigeration helium inlet of the heat exchanger unit, the high-pressure side refrigeration helium outlet of the heat exchanger unit is connected to the inlet of the first throttle valve, the outlet of the first throttle valve is connected to the low-pressure side refrigeration helium inlet of the heat exchanger unit, and the low-pressure side refrigeration helium outlet of the heat exchanger unit is connected to the inlet of the helium circulation compressor unit to form a helium refrigeration circulation loop. The heat exchanger unit's helium inlet and liquid helium outlet are connected to a helium source and a liquid helium storage tank, respectively, to form a helium liquefaction pipeline.

2. The helium liquefaction apparatus according to claim 1, characterized in that, The heat exchange unit includes a pre-cooling heat exchange unit, a turbine heat exchange unit, and a final stage heat exchange unit connected in sequence. The high-pressure side refrigeration helium inlet and low-pressure side refrigeration helium outlet of the pre-cooling heat exchange unit are respectively connected to the outlet and inlet of the helium circulation compressor unit, and the high-pressure side refrigeration helium outlet and low-pressure side refrigeration helium inlet of the final stage heat exchange unit are respectively connected to the inlet and outlet of the first throttle valve.

3. The helium liquefaction apparatus according to claim 2, characterized in that, The turbine heat exchange unit includes multiple cooling heat exchangers connected in sequence and multiple turbine expanders connected in series. The precooling heat exchange unit has a first branch and a second branch at its high-pressure side refrigeration helium outlet. The first branch is connected to the high-pressure side refrigeration helium inlet of the plurality of cooling heat exchangers, and the second branch is connected to the high-pressure side refrigeration helium inlet of the plurality of turbine expanders. The high-pressure side refrigeration helium outlet of the plurality of cooling heat exchangers is connected to the high-pressure side refrigeration helium inlet of the final stage heat exchange unit, and the low-pressure side refrigeration helium outlet of the plurality of turbine expanders is connected to the low-pressure side refrigeration helium inlet of the plurality of cooling heat exchangers.

4. The helium liquefaction apparatus according to claim 3, characterized in that, The series piping of the plurality of turbine expanders is via at least one of the plurality of cooling heat exchangers.

5. The helium liquefaction apparatus according to claim 2, characterized in that, The precooling heat exchange unit includes a liquid nitrogen precooler, a first precooling heat exchanger, and a second precooling heat exchanger. The liquid nitrogen precooler has a first heat exchange circuit and a second heat exchange circuit capable of heat exchange. The two ends of the first heat exchange circuit are respectively connected to the liquid nitrogen source and the precooling working fluid inlet of the first precooling heat exchanger, and the two ends of the second heat exchange circuit are respectively connected to the precooling working fluid outlet of the first precooling heat exchanger and the precooling working fluid inlet of the second precooling heat exchanger.

6. The helium liquefaction apparatus according to claim 5, characterized in that, The precooling heat exchange unit also includes a third precooling heat exchanger; The third precooling heat exchanger is disposed between the second precooling heat exchanger and the turbine heat exchange unit.

7. The helium liquefaction apparatus according to any one of claims 2 to 6, characterized in that, The helium liquefaction pipeline is also equipped with a second throttle valve and a third throttle valve; The second throttle valve is located between the turbine heat exchange unit and the final stage heat exchange unit, and the third throttle valve is located downstream of the final stage heat exchange unit.

8. A method of liquefying helium, characterized by, The helium liquefaction apparatus according to any one of claims 1 to 7 comprises: The refrigeration helium flows from the outlet of the helium cycle compressor unit to the heat exchange unit. After exchanging heat with the helium to be liquefied in the heat exchange unit, it is throttled and cooled by the first throttling valve and then flows back to the heat exchange unit and back to the helium cycle compressor unit, completing the helium refrigeration cycle loop. Meanwhile, the helium to be liquefied exchanges heat with the cooled helium in the heat exchange unit and is cooled into liquid helium.

9. The helium liquefaction method according to claim 8, characterized in that, The heat exchange unit includes a pre-cooling heat exchange unit, a turbine heat exchange unit, and a final stage heat exchange unit connected in sequence. In this process, the liquefied helium gas is cooled by the pre-cooling heat exchange unit and the turbine heat exchange unit and then undergoes the first throttling. After being cooled by the final heat exchange unit, it undergoes the second throttling and is converted into atmospheric pressure liquid helium.

10. The helium liquefaction method according to claim 9, characterized in that, The turbine heat exchange unit includes a plurality of cooling heat exchangers connected in sequence and a plurality of turbine expanders connected in series, wherein the series piping of the plurality of turbine expanders passes through at least one of the plurality of cooling heat exchangers. After being expanded in the first-stage turbine expander of multiple turbine expanders, the refrigerated helium gas is cooled by at least one cooling heat exchanger before entering the remaining series turbine expanders for further expansion and cooling.

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