Hydrogen liquefaction apparatus and method

Abstract

The application relates to a hydrogen liquefying device and a liquefying method. The device comprises a GM refrigerator, a compressor, a metal rod, a first cold head and a second cold head, the metal rod is connected to the outlet of the compressor, the first cold head and the second cold head are sequentially sleeved on the metal rod in the axial direction of hydrogen flow, the compressor is used for providing cold energy to the metal rod, the first cold head and the second cold head, a plurality of second circular rings are respectively and spacedly sleeved on the metal rod between the first cold head and the second cold head, an opening is arranged on each second circular ring, and the openings on adjacent second circular rings are respectively located on the two sides of the metal rod; a heat exchange cavity comprises an inner shell and an outer shell, the inner shell is used for containing the metal rod, the first cold head, the second cold head and each second circular ring, a cavity between the inner shell and the outer shell is a vacuum cavity, hydrogen to be liquefied sequentially flows through the first cold head, each second circular ring and the second cold head after passing through the outer shell and the inner shell, and a Dewar flask is used for containing liquid hydrogen. The application can improve the hydrogen liquefaction efficiency.

Description

Technical Field

[0001] This invention relates to the field of cryogenic equipment technology, and in particular to a hydrogen liquefaction device and liquefaction method. Background Technology

[0002] Hydrogen, as an important clean energy source, is increasingly widely used in industrial production. However, due to its difficulty in storage and transportation, hydrogen is typically only produced and used over short distances, severely limiting its application. Liquefying hydrogen is key to solving these storage and transportation problems.

[0003] Currently, most hydrogen liquefaction methods use a refrigerator to provide the necessary cooling energy for liquefaction, and then utilize the refrigerator's heat exchange components to exchange heat with the hydrogen for cooling. However, while existing liquefaction methods can cool hydrogen to relatively low temperatures, their heat exchange efficiency is low.

[0004] Therefore, there is an urgent need to provide a hydrogen liquefaction device and liquefaction method to improve heat exchange efficiency. Summary of the Invention

[0005] To improve the liquefaction efficiency of hydrogen, embodiments of the present invention provide a hydrogen liquefaction device and a liquefaction method.

[0006] In a first aspect, one embodiment of the present invention provides a hydrogen liquefaction apparatus, comprising: The GM chiller includes a compressor, a metal rod, a primary cold head, and a secondary cold head. The metal rod is connected to the outlet of the compressor. The primary and secondary cold heads are sequentially fitted onto the axial direction of the metal rod along the hydrogen flow direction. The compressor is used to provide cooling capacity to the metal rod, the primary cold head, and the secondary cold head. Multiple second rings are provided, each second ring being spaced apart and fitted onto the metal rod between the first-stage cold head and the second-stage cold head. Each second ring has an opening, and the openings on adjacent second rings are located on both sides of the metal rod. The heat exchange chamber includes an inner shell and an outer shell. The inner shell is used to accommodate the metal rod, the primary cold head, the secondary cold head, and each of the second rings. The chamber between the inner shell and the outer shell is a vacuum chamber. The hydrogen gas to be liquefied passes through the outer shell and the inner shell and then flows sequentially through the primary cold head, each of the second rings, and the secondary cold head. The Dewar canister, connected to the inner shell, is used to hold liquefied hydrogen gas.

[0007] Secondly, one embodiment of the present invention provides a hydrogen liquefaction method, which liquefies hydrogen using the hydrogen liquefaction apparatus provided in the above embodiment, the method comprising: The hydrogen gas to be liquefied is delivered to the inner shell space between the first-stage cold head and the compressor; The compressor is used to provide cooling capacity to the metal rod, the first-stage cold head, and the second-stage cold head; As hydrogen flows sequentially through the primary cold head, each of the second rings, and the secondary cold head, the helium is cooled and liquefied using the primary cold head, each of the second rings, and the secondary cold head, and the liquid hydrogen is stored in a Dewar flask.

[0008] This invention provides a hydrogen liquefaction apparatus and method. First, by fitting multiple second rings onto a metal rod, the low temperature of the metal rod lowers the temperature of each second ring. Then, since the openings on adjacent second rings are located on opposite sides of the metal rod, when hydrogen flows from the first-stage cold head through the uppermost second ring, it first flows along the surface of the second ring for heat exchange, that is, it flows from the opposite side of the opening to the side of the opening before flowing through the opening to the next-stage second ring. This process repeats until it reaches the second-stage cold head. This method extends the heat exchange path of the hydrogen, improving heat exchange efficiency. Therefore, this application can effectively improve the hydrogen liquefaction efficiency. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of a hydrogen liquefaction device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a structure including a GM refrigerator, a first ring, a second ring, a first heat exchange component, and a second heat exchange component, according to an embodiment of the present invention. Figure 3 for Figure 2 A partial schematic diagram at point A in the middle; Figure 4 This is a schematic diagram of a heat exchange cavity provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the outer shell of a heat exchange cavity provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the inner shell of a heat exchange cavity provided in an embodiment of the present invention; Figure 7 A schematic diagram of a Dewar jar provided according to an embodiment of the present invention; Figure 8This is a schematic diagram of a first heat exchange component provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of a first heat exchange component provided in an embodiment of the present invention from another perspective; Figure 10 This is a schematic diagram of a second heat exchange component provided in an embodiment of the present invention; Figure 11 This is a schematic diagram of a second heat exchange component provided in an embodiment of the present invention from another perspective; Figure 12 This is a schematic diagram of a nitrogen protective cover provided in an embodiment of the present invention.

[0011] Figure label: 1-GM Refrigeration Unit; 11-Compressor; 12-Metal rod; 13-First-stage cold head; 14-Second-stage cold head; 2-Second ring; 3-Heat exchange cavity; 31-Inner shell; 311 - Hydrogen inlet; 312 - Liquid delivery tube; 313 - First sleeve; 314 - Second sleeve; 315 - Third sleeve; 316 - Fourth sleeve; 32 - Outer shell; 321 - First vacuum port; 322 - Hydrogen sleeve; 4-Dewar jar; 41-Inner liner; 42-Outer liner; 43-Fifth sleeve; 44-Third vacuum port; 5-First heat exchanger assembly; 51-First heat exchange plate; 52-First fin; 53-First threaded hole; 54-First through hole; 6-Second heat exchange component; 61-Second heat exchange plate; 62-Second fin; 63-Second threaded hole; 64-Second through hole; 7-First Ring; 8-Nitrogen protective cover; 81-Second vacuum port; 82-Nitrogen inlet; 83-Unloading valve. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] like Figures 1-3 As shown, an embodiment of the present invention provides a hydrogen liquefaction device, comprising: The GM chiller 1 includes a compressor 11, a metal rod 12, a primary cold head 13, and a secondary cold head 14. The metal rod 12 is connected to the outlet of the compressor 11. The primary cold head 13 and the secondary cold head 14 are sequentially sleeved on the metal rod 12 along the direction of hydrogen flow. The compressor 11 is used to provide cooling capacity to the metal rod 12, the primary cold head 13, and the secondary cold head 14. Multiple second rings 2 are respectively fitted onto the metal rod 12 between the primary cold head 13 and the secondary cold head 14 at intervals. Each second ring 2 has an opening, and the openings on adjacent second rings 2 are located on both sides of the metal rod 12. The heat exchange chamber 3 includes an inner shell 31 and an outer shell 32. The inner shell 31 is used to accommodate the metal rod 12, the first-stage cold head 13, the second-stage cold head 14 and each second ring 2. The chamber between the inner shell 31 and the outer shell 32 is a vacuum chamber. The hydrogen gas to be liquefied passes through the outer shell 32 and the inner shell 31 and flows sequentially through the first-stage cold head 13, each second ring 2 and the second-stage cold head 14. The Dewar canister 4, connected to the inner shell 31, is used to hold liquefied hydrogen.

[0014] In this embodiment, firstly, by fitting multiple second rings 2 onto the metal rod 12, the low temperature of the metal rod 12 can be used to lower the temperature of each second ring 2. Then, since the openings on adjacent second rings 2 are located on opposite sides of the metal rod 12, when hydrogen flows from the first-stage cold head 13 through the uppermost second ring 2, the hydrogen first flows along the surface of the second ring 2 for heat exchange, that is, it flows from the opposite side of the opening to the side of the opening before flowing through the opening to the next stage of the second ring 2. This process repeats until it reaches the second-stage cold head 14. This method extends the heat exchange path of the hydrogen and improves heat exchange efficiency.

[0015] Furthermore, the second ring 2 is preferably made of a material with high thermal conductivity, such as copper. Additionally, the first-stage cold head 13 preferably cools the hydrogen gas to 50K.

[0016] It should also be noted that the bottom end of the compressor 11 is connected to the top end of the inner shell 31 and the outer shell 32 via a flange cover to form a sealed vacuum chamber and seal the first-stage cold head 13, the second-stage cold head 14, and each second ring 2 within the inner shell 31. Furthermore, since the top end of the inner shell 31 is connected to the flange cover, and the flange cover is in a normal temperature environment, heat from the environment will be transferred to the inner shell 31 and the outer shell 32 through the connection points with the flange cover. Therefore, to reduce heat transfer, the wall thickness of the inner shell 31 and the outer shell 32 should be relatively small, while still meeting strength requirements.

[0017] like Figure 8 and Figure 9 As shown, in some embodiments, a first heat exchange component 5 is also included; The first heat exchange assembly 5 includes an annular first heat exchange plate 51 and multiple first fins 52. Multiple first threaded holes 53 and multiple first through holes 54 are provided along the circumference of the first heat exchange plate 51. The distance between the center of the first through hole 54 and the center of the first heat exchange plate 51 is greater than the distance between the center of the first threaded hole 53 and the center of the first heat exchange plate 51. One end of each first fin 52 is connected to the bottom end of the first heat exchange plate 51, and the connection position does not coincide with the position of the first threaded hole 53 and the first through hole 54. The first threaded hole 53 matches the threaded hole on the first-stage cold head 13 so that the first heat exchange plate 51 can be sleeved and fixed to the bottom end of the first-stage cold head 13 by bolts. The distance between the center of the first through hole 54 and the center of the first-stage cold head 13 is greater than the sum of the radius of the first-stage cold head 13 and the radius of the first through hole 54. The first through hole 54 is used to supply hydrogen gas.

[0018] In this embodiment, the first heat exchange plate 51 is in direct contact with the first-stage cold head 13. The first-stage cold head 13 transfers cooling energy to the first heat exchange plate 51, which then transfers the cooling energy to the first fins 52. After hydrogen gas exchanges heat with the first-stage cold head 13, it flows downward through the circumferentially arranged first through-hole 54 and continues to exchange heat with each first fin 52. This increases the heat exchange area and improves the heat exchange efficiency. Furthermore, the first fin 52 has a quadrilateral cross-section. Of course, the first fin 52 can also be an I-beam or angle steel, etc. This application does not specifically limit its shape.

[0019] like Figure 10 and Figure 11 As shown, in some embodiments, a second heat exchange component 6 is also included; The second heat exchange assembly 6 includes an annular second heat exchange plate 61 and multiple second fins 62. Multiple second threaded holes 63 and multiple second through holes 64 are provided along the circumference of the second heat exchange plate 61. The distance between the center of the second through hole 64 and the center of the second heat exchange plate 61 is greater than the distance between the center of the second threaded hole 63 and the center of the second heat exchange plate 61. One end of each second fin 62 is connected to the bottom end of the second heat exchange plate 61, and the connection position does not coincide with the position of the second threaded hole 63 and the second through hole 64. The second threaded hole 63 matches the threaded hole on the secondary cold head 14 so that the second heat exchange plate 61 can be sleeved and fixed to the bottom end of the secondary cold head 14 by bolts. The distance between the center of the second through hole 64 and the center of the secondary cold head 14 is greater than the sum of the radius of the secondary cold head 14 and the radius of the second through hole 64. The second through hole 64 is used to supply hydrogen gas.

[0020] In this embodiment, the second heat exchange plate 61 is in direct contact with the secondary cold head 14. The secondary cold head 14 transfers cooling energy to the second heat exchange plate 61, which then transfers the cooling energy to the second fins 62. After hydrogen gas exchanges heat with the secondary cold head 14, it flows downward through the circumferentially arranged second through-hole 64 and continues to exchange heat with each second fin 62. This increases the heat exchange area and improves the heat exchange efficiency. Furthermore, the cross-section of the second fin 62 is quadrilateral. Of course, the second fin 62 can also be an I-beam or angle steel, etc. This application does not specifically limit its shape.

[0021] like Figure 2 As shown, in some embodiments, a plurality of first rings 7 are also included; each first ring 7 is respectively spaced and fitted on the metal rod 12 between the outlet of the compressor 11 and the first-stage cold head 13, and the material of the first ring 7 is deoxidized copper.

[0022] In this embodiment, without the first ring 7, hydrogen entering the inner shell 31 would directly contact the flange cover, hindering cooling and liquefaction. However, by setting multiple spaced-apart first rings 7, hydrogen must pass through each ring sequentially before contacting the flange cover, acting as a cooling shield and forming an effective temperature gradient. This prevents direct heat exchange between the 300K flange cover and the 50K primary cold head 13. Simultaneously, it extends the heat exchange path between the hydrogen and the flange cover, further reducing heat loss. Secondly, the first ring 7 is made of deoxidized copper. When hydrogen contacts the wall of the first ring 7, some of the hydrogen is reflected back into the normal flow channel, flowing towards the Dewar flask 4, thus reducing heat loss.

[0023] like Figure 4 and Figure 6 As shown, in some embodiments, the inner shell 31 includes a hydrogen interface 311, a liquid guide tube 312, and at least a first sleeve 313, a second sleeve 314, a third sleeve 315, and a fourth sleeve 316 that are sequentially sleeved and coaxially arranged. The top end of the first sleeve 313 is connected to the flange cover, and the bottom end is connected to the bottom end of the second sleeve 314 through a sealing ring. The top end of the second sleeve 314 is connected to the top end of the third sleeve 315 through a sealing ring. The bottom end of the third sleeve 315 is sealed to the top end of the fourth sleeve 316. The bottom end of the fourth sleeve 316 is connected to the top end of the liquid guide tube 312. The bottom end of the liquid guide tube 312 is inserted into the Dewar 4. The wall thickness of the first sleeve 313 is less than the preset value; The third sleeve 315 is used to accommodate the first annulus 7, the first-stage cold head 13 and the first heat exchange assembly 5; The fourth sleeve 316 is used to accommodate the second ring 2, the secondary cold head 14, and the second heat exchange assembly 6; The hydrogen inlet 311 is located on the third sleeve 315 between the last first ring 7 and the first-stage cold head 13.

[0024] In this embodiment, by adopting the above-mentioned connection method of each level of sleeve, the heat transfer path between the cold energy and the flange cover can be extended, the cold energy loss can be reduced, and the liquefaction efficiency can be improved.

[0025] like Figure 4 and Figure 5 As shown, in some embodiments, the outer casing 32 is provided with a first vacuum port 321 and a hydrogen sleeve 322; the external hydrogen pipeline passes through the hydrogen sleeve 322 and is connected to the hydrogen port 311.

[0026] In this embodiment, the first vacuum port 321 is used to connect to an external vacuum device to evacuate the cavity between the inner shell 31 and the outer shell 32, thereby reducing heat loss. Furthermore, hydrogen gas passes through the hydrogen sleeve 322 and then connects to the hydrogen port 311 on the inner shell 31, which further reduces heat loss.

[0027] like Figure 12 As shown, in some embodiments, a nitrogen protective cover 8 is also included to seal the compressor 11. The nitrogen protective cover 8 is filled with nitrogen, and the pressure of the nitrogen is greater than atmospheric pressure. The nitrogen protective cover 8 is equipped with a second vacuum port 81, a nitrogen inlet 82, and an unloading valve 83.

[0028] In this embodiment, hydrogen is a flammable and explosive gas. If the compressor 11 is in direct contact with the atmosphere, some hydrogen will leak into the atmosphere, posing an explosion risk. This application, by setting up a nitrogen protective cover 8 and adopting a micro-positive pressure design, can prevent hydrogen from leaking into the environment and ensure safety during the liquefaction process.

[0029] In addition, the second vacuum port 81 is used to connect to external vacuum equipment. In the initial stage of liquefaction, the nitrogen protection cover 8 is first evacuated before being filled with nitrogen to ensure the purity of the nitrogen. Furthermore, the unloading valve 83 can be opened when the pressure inside the nitrogen protection cover 8 exceeds the limit, allowing for timely pressure relief and ensuring equipment safety.

[0030] like Figure 7 As shown, in some embodiments, the Dewar 4 includes an inner liner 41, an outer liner 42, and a fifth sleeve 43 disposed in the inner liner 41; The outer liner 42 is provided with a third vacuum port 44; the bottom end of the outer shell 32 is connected to the top end of the Dewar jar 4; the bottom end of the liquid guide tube 312 is inserted into the fifth sleeve 43.

[0031] In this embodiment, the inner liner 41 contains liquid hydrogen. By providing an outer liner 42 and evacuating the cavity between the inner liner 41 and the outer liner 42, direct contact between the inner liner 41 and the atmospheric environment can be avoided, reducing convective heat transfer. By providing a fifth sleeve 43, heat transfer between the liquid hydrogen and the inner liner 41 can be further reduced.

[0032] It should also be noted that the hydrogen gas to be liquefied can enter the inner shell 31 at normal pressure. Therefore, the hydrogen gas pressure needs to be adjusted according to the gas source status.

[0033] This invention also provides a hydrogen liquefaction method, which liquefies hydrogen using the hydrogen liquefaction device provided in any of the above embodiments. The method includes: The hydrogen to be liquefied is delivered to the space of the inner shell 31 between the first-stage cold head 13 and the compressor 11; The compressor 11 provides cooling capacity to the metal rod 12, the first-stage cold head 13, and the second-stage cold head 14. As hydrogen flows sequentially through the first-stage cold head 13, each second ring 2, and the second-stage cold head 14, the helium is cooled and liquefied using the first-stage cold head 13, each second ring 2, and the second-stage cold head 14, and the liquid hydrogen is stored in the Dewar jar 4.

[0034] It should be noted that the hydrogen liquefaction method provided in this embodiment and the hydrogen liquefaction device provided in the above embodiment are based on the same inventive concept, and therefore have the same beneficial effects, which will not be elaborated here.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A hydrogen liquefaction device, characterized in that, include: The GM chiller (1) includes a compressor (11), a metal rod (12), a primary cold head (13), and a secondary cold head (14). The metal rod (12) is connected to the outlet of the compressor (11). The primary cold head (13) and the secondary cold head (14) are sequentially sleeved on the axial direction of the metal rod (12) along the hydrogen flow direction. The compressor (11) is used to provide cooling capacity to the metal rod (12), the primary cold head (13), and the secondary cold head (14). Multiple second rings (2), each second ring (2) is respectively fitted onto the metal rod (12) between the first-stage cold head (13) and the second-stage cold head (14) at intervals, each second ring (2) is provided with an opening, and the openings on adjacent second rings (2) are respectively located on both sides of the metal rod (12); The heat exchange chamber (3) includes an inner shell (31) and an outer shell (32). The inner shell (31) is used to accommodate the metal rod (12), the first-stage cold head (13), the second-stage cold head (14), and each of the second rings (2). The chamber between the inner shell (31) and the outer shell (32) is a vacuum chamber. The hydrogen gas to be liquefied passes through the outer shell (32) and the inner shell (31) and flows sequentially through the first-stage cold head (13), each of the second rings (2), and the second-stage cold head (14). The Dewar jar (4), connected to the inner shell (31), is used to hold liquefied hydrogen.

2. The apparatus according to claim 1, characterized in that, It also includes the first heat exchange component (5); The first heat exchange assembly (5) includes an annular first heat exchange plate (51) and multiple first fins (52). Multiple first threaded holes (53) and multiple first through holes (54) are provided along the circumference of the first heat exchange plate (51). The distance between the center of the first through hole (54) and the center of the first heat exchange plate (51) is greater than the distance between the center of the first threaded hole (53) and the center of the first heat exchange plate (51). One end of each first fin (52) is connected to the bottom end of the first heat exchange plate (51), and the connection position does not coincide with the position of the first threaded hole (53) and the first through hole (54). The first threaded hole (53) matches the threaded hole on the first-stage cold head (13) so that the first heat exchange plate (51) can be sleeved and fixed to the bottom end of the first-stage cold head (13) by bolts; The distance between the center of the first through hole (54) and the center of the first-stage cold head (13) is greater than the sum of the radius of the first-stage cold head (13) and the radius of the first through hole (54). The first through hole (54) is used to supply hydrogen gas.

3. The apparatus according to claim 2, characterized in that, It also includes a second heat exchange component (6); The second heat exchange assembly (6) includes an annular second heat exchange plate (61) and multiple second fins (62). Multiple second threaded holes (63) and multiple second through holes (64) are provided along the circumference of the second heat exchange plate (61). The distance between the center of the second through hole (64) and the center of the second heat exchange plate (61) is greater than the distance between the center of the second threaded hole (63) and the center of the second heat exchange plate (61). One end of each second fin (62) is connected to the bottom end of the second heat exchange plate (61), and the connection position is not located at the position of the second threaded hole (63) and the second through hole (64). The second threaded hole (63) matches the threaded hole on the secondary cold head (14) so ​​that the second heat exchange plate (61) can be sleeved and fixed to the bottom end of the secondary cold head (14) by bolts; The distance between the center of the second through hole (64) and the center of the secondary cold head (14) is greater than the sum of the radius of the secondary cold head (14) and the radius of the second through hole (64). The second through hole (64) is used to supply hydrogen gas.

4. The apparatus according to claim 3, characterized in that, It also includes multiple first rings (7); each first ring (7) is respectively spaced on the metal rod (12) between the outlet of the compressor (11) and the first-stage cold head (13), and the material of the first ring (7) is deoxidized copper.

5. The apparatus according to claim 4, characterized in that, The inner shell (31) includes a hydrogen interface (311), a liquid guide tube (312), and at least a first sleeve (313), a second sleeve (314), a third sleeve (315), and a fourth sleeve (316) that are sequentially and coaxially arranged. The top end of the first sleeve (313) is connected to the flange cover, and the bottom end is connected to the bottom end of the second sleeve (314) through a sealing ring. The top end of the second sleeve (314) is connected to the top end of the third sleeve (315) through a sealing ring. The bottom end of the third sleeve (315) is sealed to the top end of the fourth sleeve (316). The bottom end of the fourth sleeve (316) is connected to the top end of the liquid guide tube (312). The bottom end of the liquid guide tube (312) is inserted into the Dewar canister (4). The wall thickness of the first sleeve (313) is less than a preset value; The third sleeve (315) is used to accommodate the first ring (7), the first-stage cold head (13) and the first heat exchange assembly (5). The fourth sleeve (316) is used to accommodate the second ring (2), the secondary cold head (14) and the second heat exchange assembly (6). The hydrogen inlet (311) is located on the third sleeve (315) between the last first ring (7) and the first-stage cold head (13).

6. The apparatus according to claim 5, characterized in that, The outer casing (32) is provided with a first vacuum port (321) and a hydrogen sleeve (322); the external hydrogen pipeline passes through the hydrogen sleeve (322) and is connected to the hydrogen port (311).

7. The apparatus according to claim 1, characterized in that, It also includes a nitrogen protective cover (8) for sealing the compressor (11), the nitrogen protective cover (8) being filled with nitrogen and the nitrogen pressure being greater than atmospheric pressure; The nitrogen protective cover (8) is provided with a second vacuum port (81), a nitrogen inlet (82) and an unloading valve (83).

8. The apparatus according to claim 5, characterized in that, The outer wall of each of the second rings (2) does not contact the inner wall of the fourth sleeve (316).

9. The apparatus according to claim 6, characterized in that, The Dewar jar (4) includes an inner liner (41), an outer liner (42), and a fifth sleeve (43) disposed in the inner liner (41). The outer liner (42) is provided with a third vacuum port (44); the bottom end of the outer shell (32) is connected to the top end of the Dewar jar (4); the bottom end of the liquid guide tube (312) is inserted into the fifth sleeve (43).

10. A method for liquefying hydrogen, characterized in that, The method of liquefying hydrogen using the hydrogen liquefaction apparatus according to any one of claims 1-9 includes: The hydrogen to be liquefied is delivered to the inner shell (31) space between the first-stage cold head (13) and the compressor (11); The compressor (11) is used to provide cooling capacity to the metal rod (12), the primary cooling head (13) and the secondary cooling head (14); When hydrogen flows through the first-stage cold head (13), each of the second rings (2) and the second-stage cold head (14) in sequence, the hydrogen is cooled and liquefied by the first-stage cold head (13), each of the second rings (2) and the second-stage cold head (14), and the liquid hydrogen is stored in the Dewar jar (4).

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