A liquid hydrogen storage system and a hydrogen filling method capable of realizing safe filling

Abstract

The application belongs to the technical field of low-temperature frozen liquid storage, and particularly relates to a liquid hydrogen storage system capable of realizing safe filling and a hydrogen filling method. The liquid hydrogen storage system capable of realizing safe filling comprises an inner tank and an outer tank, the inner tank is arranged in the outer tank, and further comprises a vent pipe, an upper liquid inlet pipe, a lower liquid inlet pipe, a buffer tank, a compressor, a temperature monitoring element and a liquid level pressure monitoring element. The inlet end of the vent pipe is connected to the upper portion of the inner tank, the inlet end of the vent pipe is in communication with the inner tank, and the outlet end of the vent pipe is in communication with the inner tank. The buffer tank and the compressor are connected to the vent pipe, the outlet of the buffer tank is connected to the inlet of the compressor. The upper liquid inlet pipe is connected to the upper portion of the inner tank and is in communication with the inner tank. The lower liquid inlet pipe is connected to the lower portion of the inner tank and is in communication with the inner tank. The temperature monitoring element and the liquid level pressure monitoring element are arranged on the outer wall of the inner tank. The application can avoid the flow directions of gaseous hydrogen and liquid hydrogen being opposite, is more conducive to discharging gaseous hydrogen, and improves the hydrogen filling efficiency.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic frozen liquid storage technology, specifically relating to a liquid hydrogen storage system and hydrogen injection method that enables safe refilling. Background Technology

[0002] Hydrogen energy has gained widespread attention and application as a clean energy source, and the hydrogen energy storage and transportation business is booming. As a result, the requirements for liquid hydrogen storage are becoming increasingly stringent. Liquid hydrogen storage tanks are key equipment in the hydrogen energy storage and transportation business. Considering that the boiling point of liquid hydrogen is only 20K, the temperature difference between the inside and outside of the tank can easily generate large temperature stress during filling, which can damage the structure of the tank. In addition, a large amount of hydrogen gas is generated when filling the liquid hydrogen storage tank. If a large amount of hydrogen gas is directly vented, it will not only be unsafe but also cause economic waste.

[0003] Chinese patent application CN107228274A discloses a fixed multi-layer vacuum-insulated high-pressure liquid hydrogen storage tank, comprising an inner tank and an outer tank. The outer shell of the inner tank is wrapped with a fiber-reinforced epoxy resin-based composite material layer and is fixed in the cavity of the outer tank by a support member. The inner and outer tanks are a vacuum insulation interlayer, and multiple layers of vacuum radiation-proof insulation layers are laid in the vacuum insulation interlayer to cover the entire inner tank. A vacuum pumping device and a vacuum gauge connected to the vacuum insulation interlayer are provided on the outer tank.

[0004] Although the application solved the problem of wasted gaseous hydrogen, it still had the following drawbacks: its liquid hydrogen filling pipe was used for both filling liquid hydrogen and discharging gaseous hydrogen; thus, when filling liquid hydrogen, gaseous hydrogen and liquid hydrogen had opposite flow directions, which not only reduced the efficiency of hydrogen filling, but also caused gaseous hydrogen to mix with liquid hydrogen and was difficult to discharge.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a liquid hydrogen storage system and a method for safe refueling. This invention is equipped with a vent pipe, an upper liquid inlet pipe, and a lower liquid inlet pipe. Gaseous hydrogen is discharged through the vent pipe, and liquid hydrogen is injected through the upper and lower liquid inlet pipes. This avoids the opposite flow direction of gaseous and liquid hydrogen, which not only facilitates the discharge of gaseous hydrogen but also improves the efficiency of hydrogen refueling.

[0007] This invention includes the following technical solutions:

[0008] The first aspect of this invention provides a liquid hydrogen storage system capable of safe refueling, comprising an inner tank and an outer tank, the inner tank being disposed inside the outer tank, and further comprising a vent pipe, an upper inlet pipe, a lower inlet pipe, a buffer tank, a compressor, a temperature monitoring element, and a liquid level and pressure monitoring element. The inlet end of the vent pipe is connected to the upper part of the inner tank and communicates with the inner tank, and the outlet end of the vent pipe is also connected to the inner tank. The buffer tank and the compressor are connected to the vent pipe, and the outlet of the buffer tank is connected to the inlet of the compressor. The upper inlet pipe is connected to the upper part of the inner tank and communicates with the inner tank. The lower inlet pipe is connected to the lower part of the inner tank and communicates with the inner tank. The temperature monitoring element and the liquid level and pressure monitoring element are disposed on the outer wall of the inner tank.

[0009] Furthermore, the outlet end of the upper liquid inlet pipe is located inside the inner tank, and the length of the upper liquid inlet pipe located inside the inner tank is ≥ 80% of the length of the inner tank; multiple liquid outlets are provided along the axial direction of the upper liquid inlet pipe;

[0010] The length direction of the inner tank is the same as the extension direction of the liquid outlet end of the upper liquid inlet pipe.

[0011] Furthermore, the liquid outlet is connected to a nozzle.

[0012] Furthermore, the upper liquid inlet pipe includes a first horizontal section, a first vertical section, a second horizontal section, a second vertical section, and a third horizontal section. One end of the first horizontal section is located inside the inner tank, and the other end is located outside the inner tank. The first horizontal section located outside the inner tank is sequentially connected to the first vertical section, the second horizontal section, the second vertical section, and the third horizontal section.

[0013] The elevation of the first horizontal section is the same as the elevation of the third horizontal section, and the elevation of the first horizontal section is not equal to the elevation of the second horizontal section.

[0014] Furthermore, the difference between the elevation of the first horizontal section and the elevation of the second horizontal section is greater than or equal to the inner diameter of the upper liquid inlet pipe.

[0015] Furthermore, the lower liquid inlet pipe includes a fourth horizontal section, a third vertical section, a fifth horizontal section, a fourth vertical section, and a sixth horizontal section. One end of the fourth horizontal section is connected to the inner tank, and the other end is connected to the third vertical section, the fifth horizontal section, the fourth vertical section, and the sixth horizontal section in sequence.

[0016] The elevation of the fourth horizontal section is the same as that of the sixth horizontal section, but the elevation of the fourth horizontal section is not equal to that of the fifth horizontal section.

[0017] Furthermore, the difference between the elevation of the fourth horizontal section and the elevation of the fifth horizontal section is ≥ 5 times the inner diameter of the lower inlet pipe.

[0018] Furthermore, the end of the fourth horizontal section located inside the inner tank has a beveled cut.

[0019] Furthermore, it also includes a liquid hydrogen Dewar tank, which is connected to the overflow port of the inner tank via a pipe.

[0020] A second aspect of the present invention provides a hydrogen injection method, implemented based on the aforementioned hydrogen injection storage system capable of safe injection, comprising the following steps:

[0021] Liquid hydrogen is transported to the bottom of the inner tank through the upper inlet pipe for pre-cooling of the inner tank;

[0022] At the same time, the temperature of the inner tank is detected by the temperature monitoring element during the precooling process, and the liquid inlet speed of the upper liquid inlet pipe is controlled so that the temperature drop rate of the inner tank does not exceed the preset value.

[0023] When the liquid hydrogen level in the inner tank is equal to 10% of the inner tank's height, and the temperature measured by the temperature monitoring element is the preset temperature and does not change, close the upper liquid inlet pipe and open the lower liquid inlet pipe to fill the tank with liquid hydrogen. At the same time, monitor the liquid level and pressure in the inner tank through the liquid level and pressure monitoring element until the hydrogen filling is completed.

[0024] During the hydrogen injection process through the upper and lower liquid inlet pipes, gaseous hydrogen is discharged through the vent pipe and converted into liquid hydrogen by the compressor before returning to the inner tank. By adopting the above technical solution, the present invention has the following advantages:

[0025] 1. The present invention is equipped with a vent pipe, an upper liquid inlet pipe and a lower liquid inlet pipe. Gaseous hydrogen is discharged through the vent pipe and liquid hydrogen is injected through the upper liquid inlet pipe and the lower liquid inlet pipe. This can avoid the gaseous hydrogen and liquid hydrogen flowing in opposite directions, which not only facilitates the discharge of gaseous hydrogen, but also improves the hydrogen injection efficiency.

[0026] 2. The present invention uses a temperature monitoring element to monitor the temperature of the inner tank, avoids overuse of cooling, and reduces cooling costs; while the use of a liquid level and pressure monitoring element ensures safety during liquid hydrogen refueling.

[0027] 3. By setting up an upper liquid inlet pipe, the inner tank is pre-cooled by injecting hydrogen through the upper liquid inlet pipe during the hydrogen injection process, so that the inner tank is uniformly pre-cooled to the liquid hydrogen temperature range. This avoids the damage to the inner tank structure caused by the temperature difference stress caused by the large temperature difference between adjacent structures, thus ensuring safety.

[0028] 4. This invention ensures that no overflow will occur during the liquid hydrogen refueling process by setting up a liquid hydrogen Dewar tank.

[0029] 5. This invention recycles gaseous hydrogen, which can effectively avoid the waste of liquid hydrogen and has better economic efficiency.

[0030] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0031] 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.

[0032] Figure 1 This is a schematic diagram of a liquid hydrogen storage system capable of safe refueling according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the connection structure of the upper liquid inlet pipe in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the connection structure of the lower liquid inlet pipe in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of the pre-welded pad for the inner tank in an embodiment of the present invention;

[0036] In the diagram, 10-inner tank, 20-outer tank, 30-vent pipe, 40-upper liquid inlet pipe, 41-first horizontal section, 42-first vertical section, 43-second horizontal section, 44-second vertical section, 45-third horizontal section, 50-lower liquid inlet pipe, 51-fourth horizontal section, 52-third vertical section, 53-fifth horizontal section, 54-fourth vertical section, 55-sixth horizontal section, 60-buffer tank, 70-compressor, 80-temperature monitoring element, 100-nozzle, 110-liquid hydrogen Dewar canister, 120-inner tank pre-welded pad, 121-hole. Detailed Implementation

[0037] The following description provides many different embodiments or examples for implementing various features of the invention. The elements and arrangements described in the specific examples below are only for concise expression of the invention and are merely examples, not intended to limit the invention.

[0038] 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 only some embodiments of the present invention, 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.

[0039] This embodiment provides a liquid hydrogen storage system that enables safe refueling, such as... Figure 1 As shown, the system includes an inner tank 10 and an outer tank 20. The inner tank 10 is disposed inside the outer tank 20. It also includes a vent pipe 30, an upper liquid inlet pipe 40, a lower liquid inlet pipe 50, a buffer tank 60, a compressor 70, a temperature monitoring element 80, and a liquid level and pressure monitoring element. The inlet end of the vent pipe 30 is connected to the upper part of the inner tank 10 and communicates with the inner tank 10. The outlet end of the vent pipe 30 is also connected to the inner tank 10. Thus, the gaseous hydrogen discharged through the vent pipe 30 is converted into liquid hydrogen by the compressor 70 and re-enters the inner tank 10. It should be noted that the outlet end of the vent pipe 30 can be directly connected to the inner tank 10 (not shown in the figure), such as... Figure 1 The diagram shows a connection between the inner tank 10 and the lower inlet pipe 50. Figure 1 Specifically, in some embodiments, the lower inlet pipe 50 is connected to a branch pipe, which communicates with the vent pipe 30. Preferably, the vent pipe 30 is equipped with a valve.

[0040] The vent pipe 30 is connected to the buffer tank 60 and the compressor 70, and the outlet of the buffer tank 60 is connected to the inlet of the compressor 70; the upper liquid inlet pipe 40 is connected to the upper part of the inner tank 10 and communicates with the inner tank 10; the lower liquid inlet pipe 50 is connected to the lower part of the inner tank 10 and communicates with the inner tank 10; the temperature monitoring element 80 and the liquid level and pressure monitoring element are provided on the outer wall of the inner tank 10.

[0041] It should be noted that, Figure 1 Only temperature monitoring element 80 is shown. Preferably, multiple temperature monitoring elements 80 are provided. Of course, the arrangement of temperature monitoring elements 80 is not limited to this. Figure 1 As shown, preferably, the temperature monitoring elements 80 are evenly distributed on the outer wall of the inner tank 10, so that the temperature at various locations of the inner tank 10 can be monitored during hydrogen injection, and a more accurate pre-cooling temperature can be obtained. The temperature monitoring element 80 is a temperature sensor.

[0042] Figure 1 The liquid level and pressure monitoring element is not shown in the figure. The liquid level and pressure monitoring element may include a pressure sensor and a liquid level sensor.

[0043] In some embodiments, such as Figure 1 , Figure 2 As shown, the outlet end of the upper liquid inlet pipe 40 is located inside the inner tank 10. The length of the upper liquid inlet pipe 40 located inside the inner tank 10 is ≥ 80% of the length of the inner tank 10. Multiple liquid outlets are arranged along the axial direction of the upper liquid inlet pipe 40 within the inner tank 10. The length direction of the inner tank 10 is the same as the extension direction of the outlet end of the upper liquid inlet pipe 40. This makes the hydrogen injection through the upper liquid inlet pipe 40 more uniform, improves the uniformity of pre-cooling the inner tank 10, and has the advantage of improving the safety of the inner tank 10.

[0044] For example, such as Figure 1 , Figure 2 As shown, both the inner tank 10 and the outer tank 20 are horizontal tanks. The extension direction of the liquid outlet end of the upper liquid inlet pipe 40 is the axial direction of the inner tank 10. Therefore, the length direction of the inner tank 10 is the axial direction, and the length of the inner tank 10 is its axial length.

[0045] In some embodiments, such as Figure 1 , Figure 2 As shown, the liquid outlet is connected to a nozzle 100. By setting the nozzle 100, the hydrogen injection into the upper liquid inlet pipe 40 is made more uniform, improving the uniformity of precooling the inner tank 10 and thus enhancing the safety of the inner tank 10.

[0046] In some embodiments, such as Figure 2 As shown, the upper liquid inlet pipe 40 includes a first horizontal section 41, a first vertical section 42, a second horizontal section 43, a second vertical section 44, and a third horizontal section 45. One end of the first horizontal section 41 is located inside the inner tank 10, and the other end is located outside the inner tank 10. The first horizontal section 41 located outside the inner tank 10 is connected to the first vertical section 42, and the first vertical section 42 is connected to the second horizontal section 43, the second vertical section 44, and the third horizontal section 45 in sequence. The elevation of the first horizontal section 41 is the same as the elevation of the third horizontal section 45, and the elevation of the first horizontal section 41 is not equal to the elevation of the second horizontal section 43. This liquid seals the upper liquid inlet pipe 40 to prevent liquid hydrogen backflow.

[0047] It should be noted that, Figure 2 In this invention, the elevation of the first horizontal part 41 is greater than the elevation of the second horizontal part 43, but this is only illustrative; the fact that the elevation of the first horizontal part 41 is less than the elevation of the second horizontal part 43 should also be within the scope of protection of this invention.

[0048] In some embodiments, the difference between the elevation of the first horizontal section 41 and the elevation of the second horizontal section 43 is greater than or equal to the inner diameter of the upper liquid inlet pipe 40. This further improves the liquid seal effect and prevents hydrogen backflow. Preferably, the difference between the elevation of the first horizontal section 41 and the elevation of the second horizontal section 43 is greater than or equal to five times the inner diameter of the upper liquid inlet pipe 40.

[0049] In some embodiments, such as Figure 3 As shown, the lower inlet pipe 50 includes a fourth horizontal section 51, a third vertical section 52, a fifth horizontal section 53, a fourth vertical section 54, and a sixth horizontal section 55. One end of the fourth horizontal section 51 is connected to the inner tank 10, and the other end is sequentially connected to the third vertical section 52, the fifth horizontal section 53, the fourth vertical section 54, and the sixth horizontal section 55. The fourth vertical section 54 is connected to the sixth horizontal section 55. The elevation of the fourth horizontal section 51 is the same as the elevation of the sixth horizontal section 55, but the elevation of the fourth horizontal section 51 is not equal to the elevation of the fifth horizontal section 53. This liquid seal of the lower inlet pipe 50 prevents liquid hydrogen backflow.

[0050] It should be noted that, Figure 3 In this invention, the elevation of the fourth horizontal section 51 is lower than the elevation of the fifth horizontal section 53; this is merely illustrative. The fact that the elevation of the fourth horizontal section 51 is higher than the elevation of the fifth horizontal section 53 should also be within the scope of protection of this invention.

[0051] In some embodiments, the elevation difference between the fourth horizontal section 51 and the fifth horizontal section 53 is ≥ 5 times the inner diameter of the lower liquid inlet pipe 50. This further improves the liquid seal effect and prevents hydrogen backflow.

[0052] In some embodiments, such as Figure 3 As shown, the end of the fourth horizontal section 51, located inside the inner tank 10, is beveled. This increases the venting area of ​​the lower hydrogen inlet pipe, which has the advantage of improving hydrogen injection efficiency.

[0053] In some embodiments, a liquid hydrogen Dewar 110 is further included, which is connected to the overflow port of the inner tank 10. When liquid hydrogen is added to a certain level, excess liquid hydrogen can be transferred to the liquid hydrogen Dewar 110 through a pipeline, avoiding waste of liquid hydrogen and improving safety. The overflow port position is set according to the safe liquid hydrogen level, preferably exactly above the safe level; those skilled in the art will set the safe level according to actual conditions.

[0054] In some embodiments, such as Figure 4As shown, the inner tank 10 is provided with a pre-welded plate, which is used to connect the upper liquid inlet pipe 40 and the lower liquid inlet pipe 50; preferably, the pre-welded plate is provided with a hole 121.

[0055] This embodiment also provides a hydrogen injection method, based on the aforementioned hydrogen injection storage system capable of safe refueling, the hydrogen injection method comprising the following steps:

[0056] The inner tank 10 is pre-cooled, and the temperature of the inner tank 10 is detected by the temperature monitoring element 80 during the pre-cooling process. Hydrogen is first injected into the inner tank 10 through the upper liquid inlet pipe 40 to pre-cool the inner tank 10 evenly to the liquid hydrogen temperature range, so as to avoid the thermal stress caused by the excessive temperature difference between adjacent structures and damage to the structure of the inner tank 10, thus ensuring safety.

[0057] Liquid hydrogen is dripped to the bottom of the inner tank 10 through the upper liquid inlet pipe 40. The liquid inlet speed of the upper liquid inlet pipe 40 is controlled so that the temperature drop rate of the inner tank 10 does not exceed a preset value, preferably 5℃ / h.

[0058] When the liquid hydrogen level in the inner tank 10 is equal to 10% of the height of the inner tank 10, and the temperature measured by the temperature monitoring element 80 is the preset temperature and does not change, preferably, the preset temperature is -253℃; close the upper liquid inlet pipe 40 and open the lower liquid inlet pipe 50 to fill the liquid hydrogen, while monitoring the pressure of the inner tank 10 through the pressure monitoring element until the hydrogen filling is completed.

[0059] During the hydrogen injection process via the upper liquid inlet pipe 40 and the lower liquid inlet pipe 50, gaseous hydrogen is discharged through the vent pipe 30 and converted into liquid hydrogen by the compressor 70 before returning to the inner tank 10. This prevents overpressure caused by the vaporization of liquid hydrogen. Gaseous hydrogen enters the hydrogen buffer tank 60 through the vent pipe 30. After storing a certain amount of hydrogen, the hydrogen buffer tank 60 is discharged to the compressor 70 to liquefy the hydrogen, and the liquid hydrogen is then transported back to the inner tank 10.

[0060] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0061] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of multiple components or the interaction between multiple components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid hydrogen storage system capable of safe refueling, characterized in that, The system includes an inner tank (10) and an outer tank (20), with the inner tank (10) located inside the outer tank (20). It also includes a vent pipe (30), an upper inlet pipe (40), a lower inlet pipe (50), a buffer tank (60), a compressor (70), a temperature monitoring element (80), and a liquid level and pressure monitoring element. The inlet end of the vent pipe (30) is connected to the upper part of the inner tank (10), and the inlet end of the vent pipe (30) communicates with the inner tank (10). The outlet end of the vent pipe (30) is connected to the inner tank (20). 10) Connected; the vent pipe (30) is connected to the buffer tank (60) and the compressor (70), and the outlet of the buffer tank (60) is connected to the inlet of the compressor (70); the upper liquid inlet pipe (40) is connected to the upper part of the inner tank (10) and is connected to the inner tank (10); the lower liquid inlet pipe (50) is connected to the lower part of the inner tank (10) and is connected to the inner tank (10); the temperature monitoring element (80) and the liquid level pressure monitoring element are provided on the outer wall of the inner tank (10).

2. The liquid hydrogen storage system capable of safe refueling according to claim 1, characterized in that, The outlet end of the upper liquid inlet pipe (40) is located inside the inner tank (10), and the length of the upper liquid inlet pipe (40) located inside the inner tank (10) is ≥ 80% of the length of the inner tank (10); multiple liquid outlets are provided along the axial direction of the upper liquid inlet pipe (40); The length direction of the inner tank (10) is the same as the extension direction of the liquid outlet end of the upper liquid inlet pipe (40).

3. A liquid hydrogen storage system capable of safe refueling according to claim 2, characterized in that, The liquid outlet is connected to a nozzle (100).

4. A liquid hydrogen storage system capable of safe refueling according to any one of claims 1-3, characterized in that, The upper liquid inlet pipe (40) includes a first horizontal section (41), a first vertical section (42), a second horizontal section (43), a second vertical section (44), and a third horizontal section (45). One end of the first horizontal section (41) is located inside the inner tank (10), and the other end is located outside the inner tank (10). The first horizontal section (41) located outside the inner tank (10) is connected in sequence to the first vertical section (42), the second horizontal section (43), the second vertical section (44), and the third horizontal section (45). The elevation of the first horizontal section (41) is the same as the elevation of the third horizontal section (45), and the elevation of the first horizontal section (41) is not equal to the elevation of the second horizontal section (43).

5. A liquid hydrogen storage system capable of safe refueling according to claim 4, characterized in that, The difference between the elevation of the first horizontal section (41) and the elevation of the second horizontal section (43) is greater than or equal to the inner diameter of the upper liquid inlet pipe (40).

6. A liquid hydrogen storage system capable of safe refueling according to claim 1, characterized in that, The lower inlet pipe (50) includes a fourth horizontal section (51), a third vertical section (52), a fifth horizontal section (53), a fourth vertical section (54), and a sixth horizontal section (55). One end of the fourth horizontal section (51) is connected to the inner tank (10), and the other end is connected to the third vertical section (52), the fifth horizontal section (53), the fourth vertical section (54), and the sixth horizontal section (55) in sequence. The elevation of the fourth horizontal section (51) is the same as that of the sixth horizontal section (55), and the elevation of the fourth horizontal section (51) is not equal to that of the fifth horizontal section (53).

7. A liquid hydrogen storage system capable of safe refueling according to claim 6, characterized in that, The difference between the elevation of the fourth horizontal section (51) and the elevation of the fifth horizontal section (53) is greater than or equal to five times the inner diameter of the lower inlet pipe (50).

8. A liquid hydrogen storage system capable of safe refueling according to any one of claims 6-7, characterized in that, The end of the fourth horizontal section (51) located inside the inner tank (10) is obliquely cut.

9. A liquid hydrogen storage system capable of safe refueling according to claim 1, characterized in that, It also includes a liquid hydrogen Dewar tank (110), which is connected to the overflow port of the inner tank (10) via a pipe.

10. A hydrogen injection method, characterized in that, Based on the hydrogen refueling storage system described in any one of claims 1-9, the system includes the following steps: Liquid hydrogen is transported to the bottom of the inner tank (10) through the upper liquid inlet pipe (40) to pre-cool the inner tank (10); At the same time, the temperature of the inner tank (10) during the precooling process is detected by the temperature monitoring element (80), and the liquid inlet speed of the upper liquid inlet pipe (40) is controlled so that the temperature drop rate of the inner tank (10) does not exceed the preset value; When the height of liquid hydrogen in the inner tank (10) is equal to 10% of the height of the inner tank (10), and the temperature measured by the temperature monitoring element (80) is the preset temperature and does not change; close the upper liquid inlet pipe (40), open the lower liquid inlet pipe (50) to fill the liquid hydrogen, and monitor the liquid level and pressure of the inner tank (10) through the liquid level and pressure monitoring element until the hydrogen filling is completed; During the hydrogen injection process through the upper liquid inlet pipe (40) and the lower liquid inlet pipe (50), gaseous hydrogen is discharged through the vent pipe (30) and converted into liquid hydrogen by the compressor (70) and returned to the inner tank (10).

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