CN118293639A - Hydrogen liquefying device and liquefying method - Google Patents

Abstract

The present application relates to a hydrogen liquefying apparatus and a liquefying method. The device comprises: the GM refrigerator comprises a compressor, a metal rod, a first-stage cold head and a second-stage cold head, wherein the metal rod is connected to an outlet of the compressor, and the first-stage cold head and the second-stage cold head are sequentially sleeved in the axial direction of the metal rod along the hydrogen flow direction; the compressor is used for providing cooling capacity for the metal rod, the primary cold head and the secondary cold head; the second circular rings are sleeved on the metal rod between the primary cold head and the secondary cold head at intervals respectively, each second circular ring is provided with an opening, and the openings on the adjacent second circular rings are respectively positioned on two sides of the metal rod; the heat exchange cavity comprises an inner shell and an outer shell, the inner shell is used for accommodating the metal rod, the primary cold head, the secondary cold head and each second circular ring, and a cavity between the inner shell and the outer shell is a vacuum cavity; the hydrogen to be liquefied passes through the outer shell and the inner shell and then sequentially flows through the first-stage cold head, each second circular ring and the second-stage cold head; dewar tank for holding liquid hydrogen. The application can improve the liquefying efficiency of the hydrogen.

Description

Hydrogen liquefying device and liquefying method

Technical Field

The invention relates to the technical field of low-temperature equipment, in particular to a hydrogen liquefying device and a liquefying method.

Background

Hydrogen is an important clean energy source and is increasingly used in industrial production. However, hydrogen is not easy to store and transport, and is generally only produced and used in a short distance, so that the application of hydrogen is severely restricted. And liquefying hydrogen is a key to solving storage and transportation problems.

At present, a refrigerator is mostly adopted in a hydrogen liquefying mode to provide cold energy required by liquefying hydrogen, and heat exchange and cooling are performed by utilizing a heat exchange part of the refrigerator and the hydrogen. However, the existing liquefaction method can cool the hydrogen to a lower temperature, but has lower heat exchange efficiency.

Therefore, there is a need to provide a hydrogen liquefying device and a liquefying method for improving heat exchange efficiency.

Disclosure of Invention

In order to improve the liquefaction efficiency of hydrogen, the embodiment of the invention provides a hydrogen liquefaction device and a hydrogen liquefaction method.

In a first aspect, an embodiment of the present invention provides a hydrogen liquefying apparatus including:

The GM refrigerator comprises a compressor, a metal rod, a first-stage cold head and a second-stage cold head, wherein the metal rod is connected to an outlet of the compressor, and the first-stage cold head and the second-stage cold head are sequentially sleeved in the axial direction of the metal rod along the hydrogen flow direction; the compressor is used for providing cold energy for the metal rod, the primary cold head and the secondary cold head;

The second circular rings are sleeved on the metal rod between the primary cold head and the secondary cold head at intervals respectively, an opening is formed in each second circular ring, and the openings in the adjacent second circular rings are located on two sides of the metal rod respectively;

the heat exchange cavity comprises an inner shell and an outer shell, the inner shell is used for accommodating the metal rod, the primary cold head, the secondary cold head and each second circular ring, and a cavity between the inner shell and the outer shell is a vacuum cavity; the hydrogen to be liquefied passes through the outer shell and the inner shell and then sequentially flows through the primary cold head, each second circular ring and the secondary cold head;

The Dewar tank is communicated with the inner shell and is used for containing liquefied hydrogen.

In a second aspect, an embodiment of the present invention provides a method for liquefying hydrogen, where the method includes:

delivering hydrogen to be liquefied to an inner shell space between the primary coldhead and the compressor;

providing cold energy for the metal rod, the primary cold head and the secondary cold head by utilizing the compressor;

When hydrogen flows through the primary cold head, each second circular ring and the secondary cold head in sequence, the primary cold head, each second circular ring and the secondary cold head are utilized to cool and liquefy the helium, and liquid hydrogen is stored in the Dewar tank.

The embodiment of the application provides a hydrogen liquefying device and a liquefying method. First, through the cover of a plurality of second rings on the metal pole, can utilize the low temperature of metal pole to drop each second ring to lower temperature. Then, because the openings on the adjacent second circular rings are respectively positioned at two sides of the metal rod, when the hydrogen flows through the uppermost second circular ring from the first-stage cold head, the hydrogen firstly flows along the surface of the second circular ring for heat exchange, namely, after flowing from the opposite side of the opening to the side of the opening, the hydrogen can flow to the second circular ring of the next stage through the opening, and the process is repeated until the hydrogen flows to the second-stage cold head. The heat exchange path of the hydrogen can be prolonged by the mode, and the heat exchange efficiency is improved. Therefore, the application can effectively improve the liquefying efficiency of the hydrogen.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a hydrogen liquefying apparatus according to an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a GM refrigerator, a first ring, a second ring, a first heat exchange assembly, and a second heat exchange assembly according to an embodiment of the present invention;

FIG. 3 is a partial schematic view of FIG. 2 at A;

FIG. 4 is a schematic view of a heat exchange chamber according to an embodiment of the present invention;

FIG. 5 is a schematic view of a heat exchange chamber according to an embodiment of the present invention;

FIG. 6 is a schematic view of an inner shell of a heat exchange chamber according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a dewar provided in one embodiment of the present invention;

FIG. 8 is a schematic view of a first heat exchange assembly according to an embodiment of the present invention;

FIG. 9 is a schematic view of a first heat exchange assembly according to an embodiment of the present invention at another view angle;

FIG. 10 is a schematic view of a second heat exchange assembly according to an embodiment of the present invention;

FIG. 11 is a schematic view of a second heat exchange assembly according to an embodiment of the present invention at another view angle;

FIG. 12 is a schematic view of a nitrogen protection cover according to an embodiment of the present invention.

Reference numerals:

A 1-GM refrigerator;

11-a compressor; 12-a metal rod; 13-a first-stage cold head; 14-a secondary cold head;

2-a second ring;

3-a heat exchange cavity;

31-an inner shell;

311-hydrogen interface; 312-catheter; 313-a first sleeve; 314-a second sleeve; 315-a third sleeve; 316-fourth sleeve;

32-a housing;

321-a first vacuumizing interface; 322-hydrogen sleeve;

4-dewar;

41-an inner container; 42-an outer bladder; 43-fifth sleeve; 44-a third vacuumizing interface;

5-a first heat exchange assembly;

51-a first heat exchange plate; 52-first fins; 53-a first threaded hole; 54-a first through hole;

6-a second heat exchange assembly;

61-a second heat exchange plate; 62-second fins; 63-a second threaded hole; 64-a second through hole;

7-a first ring;

8-nitrogen protection cover;

81-a second vacuumizing interface; 82-nitrogen inlet; 83-unloading valve.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by persons of ordinary skill in the art without making any inventive effort based on the embodiments of the present invention are within the scope of protection of the present invention.

As shown in fig. 1 to 3, an embodiment of the present invention provides a hydrogen liquefying apparatus, including:

the GM refrigerator 1 comprises a compressor 11, a metal rod 12, a first-stage cold head 13 and a second-stage cold head 14, wherein the metal rod 12 is connected to an outlet of the compressor 11, and the first-stage cold head 13 and the second-stage cold head 14 are sequentially sleeved in the axial direction of the metal rod 12 along the hydrogen flow direction; the compressor 11 is used for providing cold energy for the metal rod 12, the primary cold head 13 and the secondary cold head 14;

the second circular rings 2 are respectively sleeved on the metal rod 12 between the primary cold head 13 and the secondary cold head 14 at intervals, an opening is formed in each second circular ring 2, and the openings in the adjacent second circular rings 2 are respectively positioned on two sides of the metal rod 12;

The heat exchange cavity 3 comprises an inner shell 31 and an outer shell 32, wherein the inner shell 31 is used for accommodating the metal rod 12, the primary cold head 13, the secondary cold head 14 and each second circular ring 2, and a cavity between the inner shell 31 and the outer shell 32 is a vacuum cavity; the hydrogen to be liquefied passes through the outer shell 32 and the inner shell 31 and then sequentially flows through the primary cold head 13, each second circular ring 2 and the secondary cold head 14;

Dewar 4, in communication with inner shell 31, is used to hold liquefied hydrogen.

In this embodiment, first, by sleeving the plurality of second rings 2 on the metal rod 12, each of the second rings 2 can be lowered to a lower temperature by using the low temperature of the metal rod 12. Then, since the openings on the adjacent second rings 2 are located on both sides of the metal rod 12, respectively, when the hydrogen gas flows from the first-stage coldhead 13 through the uppermost second ring 2, the hydrogen gas firstly flows along the surface of the second ring 2 to exchange heat, that is, flows from the opposite side of the opening to the opening side and then flows to the second ring 2 of the next stage through the opening, and then, the above steps are repeated until the hydrogen gas flows to the second-stage coldhead 14. The heat exchange path of the hydrogen can be prolonged by the mode, and the heat exchange efficiency is improved.

The second ring 2 is preferably made of a material having a high thermal conductivity such as copper. In addition, the primary coldhead 13 preferably cools the hydrogen to 50K.

It should be noted that, the bottom end of the compressor 11 is connected to the top ends of the inner shell 31 and the outer shell 32 through flange covers, so as to form a closed vacuum chamber and seal the primary cold head 13, the secondary cold head 14 and each second ring 2 in the inner shell 31. In addition, since the top end of the inner case 31 is connected to the flange cover, which is in a normal temperature environment, heat in the environment is transferred to the inner case 31 and the outer case 32 through the connection of the inner case 31 and the outer case 32 to the flange cover. Therefore, in order to reduce the heat transfer amount, the wall thickness of the inner shell 31 and the outer shell 32 should be selected to be smaller on the premise of satisfying the strength.

As shown in fig. 8 and 9, in some embodiments, a first heat exchange assembly 5 is also included;

The first heat exchange assembly 5 includes a circular ring-shaped first heat exchange plate 51 and a plurality of first fins 52, and a plurality of first screw holes 53 and a plurality of first through holes 54 are provided along the circumferential direction 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 screw hole 53 and the center of the first heat exchange plate 51; one end of each first fin 52 is connected with the bottom end of the first heat exchange plate 51, and the connection position is not overlapped with the positions of the first threaded holes 53 and the first through holes 54;

the first threaded hole 53 is matched with the threaded hole on the primary cold head 13, so that the first heat exchange plate 51 is sleeved and fixed at the bottom end of the primary cold head 13 through bolts;

The distance between the center of the first through hole 54 and the center of the primary cold head 13 is greater than the sum of the radius of the primary cold head 13 and the radius of the first through hole 54, and the first through hole 54 is used for hydrogen circulation.

In this embodiment, the first heat exchange plate 51 is in direct contact with the primary cold head 13, the primary cold head 13 transfers the cold to the first heat exchange plate 51, and the first heat exchange plate 51 transfers the cold to the first fin 52. After the hydrogen exchanges heat with the primary cold head 13, the hydrogen flows downwards through the first through holes 54 arranged in the circumferential direction and then exchanges heat with each first fin 52 continuously, so that the heat exchange area can be increased, and the heat exchange efficiency is improved. The cross section of the first fin 52 is quadrangular, and of course, the first fin 52 may be i-steel, angle steel, or the like, and the shape thereof is not particularly limited in the present application.

As shown in fig. 10 and 11, in some embodiments, a second heat exchange assembly 6 is also included;

The second heat exchange assembly 6 includes a circular ring-shaped second heat exchange plate 61 and a plurality of second heat exchange fins 62, and a plurality of second screw holes 63 and a plurality of second through holes 64 are provided along the circumferential direction 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 screw hole 63 and the center of the second heat exchange plate 61; one end of each second heat exchange fin 62 is connected with the bottom end of the second heat exchange plate 61, and the connection position is not overlapped with the positions of the second threaded holes 63 and the second through holes 64;

the second threaded hole 63 is matched with the threaded hole on the secondary cold head 14 so as to sleeve and fix the second heat exchange plate 61 at the bottom end of the secondary cold head 14 through 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, and the second through hole 64 is used for hydrogen circulation.

In this embodiment, the second heat exchange plate 61 is in direct contact with the secondary coldhead 14, the secondary coldhead 14 transferring coldness to the second heat exchange plate 61, and the second heat exchange plate 61 in turn transferring coldness to the second heat exchange fins 62. After the hydrogen exchanges heat with the secondary cooling heads 14, the hydrogen flows downwards through the second through holes 64 arranged in the circumferential direction and then exchanges heat with each second heat exchange fin 62 continuously, so that the heat exchange area can be increased, and the heat exchange efficiency is improved. The cross section of the second fin 62 is quadrangular, and of course, the second fin 62 may be i-steel, angle steel, or the like, and the shape thereof is not particularly limited in the present application.

As shown in fig. 2, in some embodiments, a plurality of first rings 7 are also included; each first circular ring 7 is respectively sleeved on a metal rod 12 between the outlet of the compressor 11 and the primary cold head 13 at intervals, and the material of the first circular ring 7 is deoxidized copper.

In this embodiment, if the first ring 7 is not provided, the hydrogen gas directly contacts the flange cover after entering the inner shell 31, which is unfavorable for cooling and liquefying. By arranging a plurality of first circular rings 7 which are arranged at intervals, hydrogen can sequentially pass through each stage of first circular rings 7 and can be contacted with the flange cover, so that the effect of a cold screen is achieved, an effective temperature gradient is formed, and the direct heat exchange between the flange cover of 300K and the primary cold head 13 of 50K is avoided; meanwhile, the heat exchange path of the hydrogen and the flange cover is prolonged, and heat exchange loss is further reduced. Secondly, the material of the first ring 7 is deoxidized copper, and when the hydrogen contacts with the wall surface of the first ring 7, part of the hydrogen is reflected back to the normal flow channel, i.e. flows towards the Dewar 4, so that the heat loss is reduced.

As shown in fig. 4 and 6, in some embodiments, the inner shell 31 includes a hydrogen gas port 311, a catheter 312, and at least a first cannula 313, a second cannula 314, a third cannula 315, and a fourth cannula 316 that are nested in sequence and coaxially disposed;

The top end of the first sleeve 313 is connected with the flange cover, the bottom end is connected with the bottom end of the second sleeve 314 through a sealing ring, the top end of the second sleeve 314 is connected with the top end of the third sleeve 315 through a sealing ring, the bottom end of the third sleeve 315 is connected with the top end of the fourth sleeve 316 in a sealing way, the bottom end of the fourth sleeve 316 is communicated with the top end of the liquid guide tube 312, and 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 a preset value;

the third sleeve 315 is used for accommodating the first annular ring 7, the primary cold head 13 and the first heat exchange assembly 5;

The fourth sleeve 316 is used for accommodating the second ring 2, the secondary cooling head 14 and the second heat exchange assembly 6;

the hydrogen interface 311 is arranged on the third sleeve 315 between the last first ring 7 and the primary cold head 13.

In the embodiment, by adopting the connection mode of the sleeves of each stage, the heat transfer path between the cold quantity and the flange cover can be prolonged, the cold quantity loss is reduced, and the liquefaction efficiency is improved.

As shown in fig. 4 and 5, in some embodiments, a first vacuum port 321 and a hydrogen sleeve 322 are provided on the housing 32; an external hydrogen line is connected to the hydrogen interface 311 after passing through the hydrogen sleeve 322.

In this embodiment, the first vacuum port 321 is used to connect with an external vacuum device to vacuum the cavity between the inner shell 31 and the outer shell 32, and reduce the amount of leakage heat. In addition, the hydrogen passes through the hydrogen sleeve 322 and then is connected with the hydrogen interface 311 on the inner shell 31, so that heat loss can be further reduced.

As shown in fig. 12, in some embodiments, the apparatus further includes a nitrogen protection cover 8 for sealing the compressor 11, wherein the nitrogen protection cover 8 is filled with nitrogen, and the pressure of the nitrogen is greater than the atmospheric pressure;

the nitrogen protection cover 8 is provided with a second vacuumizing interface 81, a nitrogen inlet 82 and an unloading valve 83.

In this embodiment, the hydrogen is a flammable and explosive gas. If the compressor 11 is in direct contact with the atmosphere, part of the hydrogen will leak into the atmosphere, causing explosion risk. According to the application, the nitrogen protection cover 8 is arranged, and the micro-positive pressure design is adopted, so that hydrogen can be prevented from leaking into the environment, and the safety in the liquefaction process is ensured.

In addition, the second vacuumizing interface 81 is used for being connected with an external vacuumizing device, and in the initial liquefaction stage, after the nitrogen protection cover 8 is vacuumized, nitrogen is filled into the nitrogen protection cover, so that the purity of the nitrogen is guaranteed. In addition, the unloading valve 83 can be opened when the pressure in the nitrogen protection cover 8 is over-pressure, so that the pressure is released in time, and the safety of equipment is ensured.

As shown in fig. 7, in some embodiments, dewar 4 includes an inner bladder 41, an outer bladder 42, and a fifth sleeve 43 disposed in inner bladder 41;

The outer liner 42 is provided with a third vacuumizing interface 44; the bottom end of the housing 32 is connected to the top end of the dewar 4; the bottom end of the catheter 312 is inserted into the fifth cannula 43.

In this embodiment, 4.2K of liquid hydrogen is stored in the inner container 41, and by providing the outer container 42 and vacuumizing the cavity between the inner container 41 and the outer container 42, direct contact between the inner container 41 and the atmospheric environment can be avoided, and convective heat transfer is reduced. By providing the fifth sleeve 43, heat exchange between the liquid hydrogen and the inner liner 41 can be reduced.

It should be noted that the hydrogen to be liquefied may enter the inner shell 31 in a normal pressure state, and thus, the pressure of the hydrogen needs to be adjusted according to the gas source state.

The embodiment of the invention also provides a hydrogen liquefying method, which utilizes the hydrogen liquefying device provided by any embodiment to liquefy hydrogen, and comprises the following steps:

Delivering hydrogen to be liquefied to the space of inner shell 31 between primary coldhead 13 and compressor 11;

the compressor 11 is utilized to provide cold energy for the metal rod 12, the primary cold head 13 and the secondary cold head 14;

When hydrogen flows through the primary cold head 13, each second circular ring 2 and the secondary cold head 14 in sequence, the primary cold head 13, each second circular ring 2 and the secondary cold head 14 are utilized to cool and liquefy helium gas, and liquid hydrogen is stored in the dewar tank 4.

It should be noted that, the hydrogen liquefaction method provided in this embodiment and the hydrogen liquefaction device provided in the foregoing embodiments are based on the same inventive concept, so that the two have the same beneficial effects, and are not described herein.

It is noted that relational terms such as first and second, and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A hydrogen liquefying apparatus, comprising:

The GM refrigerator (1) comprises a compressor (11), a metal rod (12), a first-stage cold head (13) and a second-stage cold head (14), wherein the metal rod (12) is connected to an outlet of the compressor (11), and the first-stage cold head (13) and the second-stage cold head (14) are sequentially sleeved in the axial direction of the metal rod (12) along the hydrogen flow direction; the compressor (11) is used for providing cooling capacity for the metal rod (12), the primary cooling head (13) and the secondary cooling head (14);

The second circular rings (2) are sleeved on the metal rod (12) between the primary cold head (13) and the secondary cold head (14) at intervals respectively, each second circular ring (2) is provided with an opening, and the openings on the adjacent second circular rings (2) are positioned on two sides of the metal rod (12) respectively;

The heat exchange cavity (3) comprises an inner shell (31) and an outer shell (32), the inner shell (31) is used for accommodating the metal rod (12), the primary cold head (13), the secondary cold head (14) and each second circular ring (2), and a cavity between the inner shell (31) and the outer shell (32) is a vacuum cavity; the hydrogen to be liquefied passes through the outer shell (32) and the inner shell (31) and then sequentially flows through the primary cold head (13), each second circular ring (2) and the secondary cold head (14);

and the Dewar tank (4) is communicated with the inner shell (31) and is used for containing liquefied hydrogen.

2. The apparatus according to claim 1, further comprising a first heat exchange assembly (5);

the first heat exchange assembly (5) comprises a circular first heat exchange plate (51) and a plurality of first fins (52), and a plurality of first threaded holes (53) and a plurality of first through holes (54) are formed in the circumferential direction of the first heat exchange plate (51); a distance between the center of the first through hole (54) and the center of the first heat exchange plate (51) is greater than a distance between the center of the first screw hole (53) and the center of the first heat exchange plate (51); one end of each first fin (52) is connected with the bottom end of the first heat exchange plate (51) respectively, and the connection position is not overlapped with the positions of the first threaded holes (53) and the first through holes (54);

the first threaded hole (53) is matched with the threaded hole on the primary cold head (13) so as to sleeve and fix the first heat exchange plate (51) at the bottom end of the primary cold head (13) through bolts;

The distance between the center of the first through hole (54) and the center of the primary cold head (13) is larger than the sum of the radius of the primary cold head (13) and the radius of the first through hole (54), and the first through hole (54) is used for hydrogen circulation.

3. The apparatus according to claim 2, further comprising a second heat exchange assembly (6);

The second heat exchange assembly (6) comprises a circular second heat exchange plate (61) and a plurality of second heat exchange fins (62), and a plurality of second threaded holes (63) and a plurality of second through holes (64) are formed in the circumferential direction of the second heat exchange plate (61); a distance between the center of the second through hole (64) and the center of the second heat exchange plate (61) is greater than a distance between the center of the second screw hole (63) and the center of the second heat exchange plate (61); one end of each second heat exchange fin (62) is connected with the bottom end of the second heat exchange plate (61) respectively, and the connection position is not positioned at the positions of the second threaded holes (63) and the second through holes (64);

The second threaded hole (63) is matched with the threaded hole on the secondary cold head (14) so as to sleeve and fix the second heat exchange plate (61) at the bottom end of the secondary cold head (14) through bolts;

The distance between the center of the second through hole (64) and the center of the secondary cold head (14) is larger than the sum of the radius of the secondary cold head (14) and the radius of the second through hole (64), and the second through hole (64) is used for hydrogen circulation.

4. A device according to claim 3, further comprising a plurality of first rings (7); each first circular ring (7) is sleeved on a metal rod (12) between the outlet of the compressor (11) and the primary cold head (13) at intervals, and the first circular rings (7) are made of deoxidized copper.

5. The device according to claim 4, wherein the inner housing (31) comprises a hydrogen interface (311), a catheter (312) and at least a first cannula (313), a second cannula (314), a third cannula (315) and a fourth cannula (316) which are sleeved in sequence and coaxially arranged;

The top end of the first sleeve (313) is connected with the flange cover, the bottom end of the first sleeve is connected with the bottom end of the second sleeve (314) through a sealing ring, the top end of the second sleeve (314) is connected with the top end of the third sleeve (315) through a sealing ring, the bottom end of the third sleeve (315) is connected with the top end of the fourth sleeve (316) in a sealing manner, the bottom end of the fourth sleeve (316) is communicated with the top end of the liquid guide tube (312), and the bottom end of the liquid guide tube (312) is inserted into the dewar tank (4);

The wall thickness of the first sleeve (313) is smaller than a preset value;

the third sleeve (315) is used for accommodating the first circular ring (7), the primary cold head (13) and the first heat exchange assembly (5);

the fourth sleeve (316) is used for accommodating the second circular ring (2), the secondary cold head (14) and the second heat exchange assembly (6);

the hydrogen interface (311) is arranged on a third sleeve (315) between the last first circular ring (7) and the primary cold head (13).

6. The device according to claim 5, characterized in that the housing (32) is provided with a first vacuum interface (321) and a hydrogen sleeve (322); an external hydrogen pipeline passes through the hydrogen sleeve (322) and then is connected with the hydrogen interface (311).

7. The device according to claim 1, further comprising a nitrogen protection cover (8) for sealing the compressor (11), the nitrogen protection cover (8) being filled with nitrogen, and the pressure of the nitrogen being greater than atmospheric pressure;

the nitrogen protection cover (8) is provided with a second vacuumizing interface (81), a nitrogen inlet (82) and an unloading valve (83).

8. The device according to claim 5, characterized in that the outer wall of each second ring (2) is not in contact with the inner wall of the fourth sleeve (316).

9. The device according to claim 6, characterized in that the dewar (4) comprises a liner (41), an outer liner (42) and a fifth sleeve (43) arranged in the liner (41);

A third vacuumizing interface (44) is arranged on the outer liner (42); the bottom end of the shell (32) is connected with the top end of the dewar tank (4); the bottom end of the catheter (312) is inserted into the fifth cannula (43).

10. A method for liquefying hydrogen gas, characterized by liquefying hydrogen gas by using the hydrogen liquefying apparatus according to any one of claims 1 to 9, the method comprising:

Delivering hydrogen to be liquefied to an inner shell (31) space between the primary coldhead (13) and the compressor (11);

Providing cooling capacity for the metal rod (12), the primary cooling head (13) and the secondary cooling head (14) by utilizing the compressor (11);

When hydrogen flows through the primary cold head (13), each second circular ring (2) and the secondary cold head (14) in sequence, the primary cold head (13), each second circular ring (2) and the secondary cold head (14) are utilized to cool and liquefy helium, and liquid hydrogen is stored in the Dewar tank (4).