A soft-cooled screen liquid hydrogen refueling system and method

Abstract

This invention discloses a liquid hydrogen refueling system and method with a soft-cooled shield, relating to the field of liquid hydrogen technology. The system includes a liquid hydrogen supply tank and a liquid hydrogen refueling tank. During the liquid hydrogen storage stage, the cooling energy of evaporated low-temperature hydrogen causes the medium inside the cooling shield to change from a liquid to a solid state, achieving cold energy storage and improving the insulation performance of the liquid hydrogen storage tank. During the refueling stage, the liquid hydrogen medium inside the liquid hydrogen storage tank has been emptied, and the medium in the open cooling shield gradually changes from a solid to a liquid state, maintaining the tank at a low temperature and reducing the time required for subsequent pre-cooling operations. Using a designed S-shaped capillary connector, a small portion of liquefied high-density and low-density media can enter the inner tank for vaporization without affecting the insulation capacity, maintaining a slight positive pressure inside the liquid hydrogen refueling tank. Simultaneously, the low-density and high-density media are arranged sequentially from top to bottom, allowing the vaporized gas to stratify, effectively preventing external air from entering and reducing the time required for subsequent replacement operations.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid hydrogen, and particularly to a soft cold screen liquid hydrogen filling system and method. Background Technique

[0002] The hydrogen energy industry chain includes hydrogen production, storage, transportation, and application. Among them, hydrogen storage and transportation is the key link connecting the upstream and downstream of the hydrogen energy industry chain, and it is also the main bottleneck for the efficient storage and transportation and large-scale utilization of hydrogen energy at present. The storage and transportation methods of hydrogen energy include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and metal hydride hydrogen storage. Among them, cryogenic liquid hydrogen storage has the advantages of high mass hydrogen storage density, high filling efficiency, and good safety, and it is an ideal hydrogen storage technology in the future. However, the boiling point of liquid hydrogen is extremely low, and vaporization loss inevitably occurs during storage and transportation. Therefore, cryogenic liquid hydrogen storage has high requirements for the heat insulation and reliability of the device. Due to the late start of the development of liquid hydrogen in China, the key technologies in the storage and transportation link are backward, and the relevant liquid hydrogen standards are not perfect, which seriously restricts the large-scale application of liquid hydrogen.

[0003] The common shapes of liquid hydrogen storage tanks include cylindrical, spherical, conical, and flat-bottomed. According to the different volumes of the storage tanks, the shapes of the storage tanks and the heat insulation methods will also vary. The common structures of liquid hydrogen storage tanks are cylindrical and spherical. The cylindrical shape is suitable for storage tanks with a geometric volume less than 500m 3 of the storage tank, and the heat insulation method is mostly high-vacuum multi-layer heat insulation. The spherical storage tank is suitable for storage tanks with a geometric volume greater than 200m 3 of the storage tank. Due to its large heat insulation space and the difficulty of winding multi-layer heat insulation materials, vacuum powder heat insulation is generally used. The heat insulation materials include perlite sand, aerogel, fiber, and hollow glass microspheres, etc. However, before the filling and transfer process of liquid hydrogen, it is usually necessary to perform operations such as replacement and precooling on equipment such as liquid hydrogen storage tanks, and it takes a lot of time, which limits the filling and transfer efficiency of liquid hydrogen and is not conducive to the large-scale popularization and use of liquid hydrogen. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a soft cold screen liquid hydrogen filling system and method. The present invention realizes the utilization of the cryogenic evaporation gas cold energy during the liquid hydrogen storage process and the long-term cold preservation target of the liquid hydrogen storage tank by designing an open soft cold screen, and by structural design, maintains the positive pressure inside the storage tank, effectively reducing the time required for replacement and cooling during the filling or transfer of the liquid hydrogen storage tank.

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] In the first aspect, the present invention provides a soft cold screen liquid hydrogen filling system, including a liquid hydrogen supply tank and a liquid hydrogen filling tank;

[0007] The liquid hydrogen supply tank is equipped with a liquid hydrogen pressurization pipeline and a liquid hydrogen filling pipeline. The bottom of the liquid hydrogen supply tank is connected to the top of the liquid hydrogen supply tank via a liquid hydrogen pressurization pipeline, which is sequentially equipped with a first liquid hydrogen shut-off valve and a liquid hydrogen vaporizer, forming a circulation loop. The liquid hydrogen filling tank includes an outer tank and an inner tank, which are nested alternately, with the interval between them being a vacuum environment. The bottom of the liquid hydrogen supply tank is connected to the bottom of the inner tank via a liquid hydrogen filling pipeline, which is sequentially equipped with a second liquid hydrogen shut-off valve and a third liquid hydrogen shut-off valve. The top of the inner tank is connected to an venting pipeline equipped with a vent valve, a pressurization pipeline equipped with a pressurization valve, and a hydrogen cooling pipeline, respectively. The bottom is connected to a delivery pipeline equipped with a fourth liquid hydrogen shut-off valve. The ends of the pressurization pipeline and the delivery pipeline are respectively equipped with connecting flanges. The interval area is equipped with... The device comprises a low-density phase change cooling screen and a high-density phase change cooling screen. The top of the inner tank is connected in sequence to a hydrogen shut-off valve, the inner channel of the low-density phase change cooling screen, the inner channel of the high-density phase change cooling screen, and the outside via a hydrogen cooling pipeline. The front end of the low-density phase change cooling screen is connected to a low-density medium tank via a low-density medium filling pipeline equipped with a low-density medium filling valve, and the bottom is connected in sequence to a first S-type capillary connector, a low-density medium shut-off valve, and a low-density medium vaporizer. The front end of the high-density phase change cooling screen is connected to a high-density medium tank via a high-density medium filling pipeline equipped with a high-density medium filling valve, and the bottom is connected in sequence to a second S-type capillary connector, a high-density medium shut-off valve, and a high-density medium vaporizer. The outlets of both the low-density and high-density medium vaporizers are located inside the inner tank.

[0008] Preferably, the low-density phase change cooling screen and the high-density medium vaporizer are at the same horizontal distance from the inner tank.

[0009] Preferably, the hydrogen shut-off valve, the first S-type capillary connector, the low-density medium shut-off valve, the low-density medium vaporizer, the second S-type capillary connector, the high-density medium shut-off valve, and the high-density medium vaporizer are all located within the interval area, while the vent valve, the pressure boosting valve, the connecting flange, the low-density medium tank, the low-density medium filling valve, the high-density medium tank, and the high-density medium filling valve are all located outside the liquid hydrogen filling tank.

[0010] Preferably, the shell of the low-density phase change cold screen is filled with a low-density medium, which can form a heat exchange contact with the inner channel of the low-density phase change cold screen; the shell of the high-density phase change cold screen is filled with a high-density medium, which can form a heat exchange contact with the inner channel of the high-density phase change cold screen.

[0011] Furthermore, the low-density medium is liquid nitrogen, and the high-density medium is liquid argon.

[0012] Preferably, both the low-density medium vaporizer and the high-density medium vaporizer are unidirectional passages, allowing the medium to be introduced into the inner tank only.

[0013] Preferably, the liquid hydrogen pressurization pipeline, liquid hydrogen filling pipeline, and hydrogen cooling pipeline are all wrapped with heat-insulating material.

[0014] Preferably, both the first S-type capillary connector and the second S-type capillary connector are wrapped with a low thermal conductivity material on the outside and filled with a porous material on the inside.

[0015] Preferably, both the low-density phase change cooling screen and the high-density phase change cooling screen have metal fins on the outer side of their inner channels to enhance heat conduction.

[0016] Secondly, the present invention provides a control method for the soft-cooled screen liquid hydrogen refueling system described in any of the first aspects, as follows:

[0017] All valves are closed, and all equipment is stopped.

[0018] S1: Open the low-density medium filling valve. The low-density medium from the low-density medium tank enters the low-density phase change cold screen through the low-density medium filling pipeline. After the low-density medium in the low-density phase change cold screen reaches the set liquid level, stop filling and close the low-density medium filling valve.

[0019] Open the high-density medium filling valve, and the high-density medium from the high-density medium tank enters the high-density phase change cold screen through the high-density medium filling pipeline; after the high-density medium in the high-density phase change cold screen reaches the set liquid level, stop filling and close the high-density medium filling valve.

[0020] Open the first liquid hydrogen shut-off valve; some liquid hydrogen at the bottom of the liquid hydrogen supply tank enters the liquid hydrogen pressurization pipeline, then enters the liquid hydrogen vaporizer through the first liquid hydrogen shut-off valve to absorb heat and vaporize, and finally enters the gas phase space at the top of the liquid hydrogen supply tank for pressurization, so that the liquid hydrogen supply tank has the ability to supply liquid to the outside.

[0021] Open the second liquid hydrogen shut-off valve, the third liquid hydrogen shut-off valve, and the vent valve; liquid hydrogen from the liquid hydrogen supply tank enters the liquid hydrogen filling pipeline, flows sequentially through the second liquid hydrogen shut-off valve, the third liquid hydrogen shut-off valve, the outer tank, and the inner tank, pre-cooling the liquid hydrogen filling pipeline and the inner tank, and finally vents through the vent valve; after pre-cooling is completed, continue to add liquid hydrogen to the inner tank through the liquid hydrogen filling pipeline until the set liquid level of the inner tank is reached, the filling is completed, and the first liquid hydrogen shut-off valve, the second liquid hydrogen shut-off valve, and the third liquid hydrogen shut-off valve are closed;

[0022] S2: Open the hydrogen shut-off valve and close the vent valve; the low-temperature hydrogen generated inside the inner tank enters the hydrogen cooling pipeline through the hydrogen shut-off valve, first entering the inner channel of the low-density phase change cold shield, causing the low-density medium inside the low-density phase change cold shield to solidify, then entering the inner channel of the high-density phase change cold shield, causing the high-density medium inside the high-density phase change cold shield to solidify, realizing the recovery of cold energy from the low-temperature cold gas, and finally venting through the hydrogen cooling pipeline; the low-density phase change cold shield and the high-density phase change cold shield after the medium solidifies further enhance the insulation capacity between the outer tank and the inner tank;

[0023] S3: Open the high-density medium shut-off valve; the solid high-density medium inside the high-density phase change cold screen slowly absorbs external heat and partially liquefies, prolonging the time the inner tank maintains a low temperature state. The liquefied high-density medium enters the second S-type capillary connector, and under the action of capillary force, it passes through the high-density medium shut-off valve to reach the high-density medium vaporizer. After absorbing external heat, it gradually vaporizes and enters the inner tank.

[0024] Open the low-density medium shut-off valve; the solid low-density medium inside the low-density phase change cold screen slowly absorbs external heat and partially liquefies, prolonging the time the inner tank maintains a low temperature state. The liquefied low-density medium enters the first S-type capillary connector, and under the action of capillary force, it passes through the low-density medium shut-off valve to reach the low-density medium vaporizer. After absorbing external heat, it gradually vaporizes and enters the inner tank.

[0025] Due to the density difference, the vaporized low-density and high-density media form a gradient distribution in the inner tank and maintain a slight positive pressure. The gas is slowly vented through the vent valve. The first S-type capillary connector and the second S-type capillary connector can automatically extend the time of the liquid low-density and liquid high-density media, so that the inner tank can maintain a low temperature and high purity state for a longer period of time, reducing the replacement and pre-cooling time required for subsequent liquid hydrogen refueling.

[0026] The outstanding and beneficial technical effects of this invention compared to existing technologies are as follows: A liquid hydrogen storage tank with an open-type soft cooling screen is designed. During the liquid hydrogen storage stage, the cooling energy of the evaporated low-temperature hydrogen gas causes the medium inside the cooling screen to change from a liquid to a solid state, achieving cold energy storage and improving the insulation performance of the liquid hydrogen storage tank. During the filling stage, the liquid hydrogen medium inside the liquid hydrogen storage tank has been emptied, and the medium in the open-type cooling screen gradually changes from a solid to a liquid state, keeping the tank at a low temperature and reducing the time required for subsequent pre-cooling operations. Using a designed S-shaped capillary connector, a small portion of liquefied high-density and low-density media can enter the inner tank for vaporization without affecting the insulation capacity, maintaining a slight positive pressure inside the liquid hydrogen filling tank. Simultaneously, the sequential arrangement of low-density and high-density media from top to bottom allows for stratification of the vaporized gas, effectively preventing external air from entering and reducing the time required for subsequent replacement operations.

[0027] The following will further explain the concept, specific structure and technical effects of the present invention with reference to the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a soft-cooled screen liquid hydrogen refueling system according to the present invention.

[0029] In the diagram: 1. Liquid hydrogen pressurization pipeline; 2. Liquid hydrogen supply tank; 3. First liquid hydrogen shut-off valve; 4. Liquid hydrogen vaporizer; 5. Liquid hydrogen filling pipeline; 6. Second liquid hydrogen shut-off valve; 7. Third liquid hydrogen shut-off valve; 8. Outer tank; 9. Inner tank; 10. Exhaust valve; 11. Pressurization valve; 12. Connecting flange; 13. Fourth liquid hydrogen shut-off valve; 14. Hydrogen cooling pipeline; 15. Hydrogen shut-off valve; 16. Low-density phase change cooling screen; 17. Low-density medium; 18. First S-type capillary connector; 19. Low-density medium shut-off valve; 20. Low-density medium vaporizer; 21. High-density phase change cooling screen; 22. High-density medium; 23. Second S-type capillary connector; 24. High-density medium shut-off valve; 25. High-density medium vaporizer; 26. Low-density medium filling pipeline; 27. Low-density medium tank; 28. Low-density medium filling valve; 29. ​​High-density medium tank; 30. High-density medium filling valve. Detailed Implementation

[0030] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0031] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0032] In the description of this invention, it should be understood that the terms "first," "second," "third," and "fourth" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," and "fourth" may explicitly or implicitly include at least one of those features.

[0033] In the description of this invention, it should be understood that the terms "low density" and "high density" in the accompanying drawings, such as "low-density phase change cooling screen 16, low-density medium 17, low-density medium shut-off valve 19, low-density medium vaporizer 20, high-density phase change cooling screen 21, high-density medium 22, high-density medium shut-off valve 24, high-density medium vaporizer 25, low-density medium filling pipeline 26, low-density medium tank 27, low-density medium filling valve 28, high-density medium filling pipeline 29, high-density medium tank 30, and high-density medium filling valve 31," are used only for descriptive purposes and refer to "low density" and "high density" in a relative sense. They should not be construed as indicating or implying relative importance or implicitly specifying the density limitation of the indicated technical features.

[0034] like Figure 1 As shown, this invention provides a soft-cooled screen liquid hydrogen refueling system. The system mainly includes a liquid hydrogen pressurization pipeline 1, a liquid hydrogen supply tank 2, a first liquid hydrogen shut-off valve 3, a liquid hydrogen vaporizer 4, a liquid hydrogen refueling pipeline 5, a second liquid hydrogen shut-off valve 6, a third liquid hydrogen shut-off valve 7, an outer tank 8, an inner tank 9, an vent valve 10, a pressurization valve 11, a connecting flange 12, a fourth liquid hydrogen shut-off valve 13, a hydrogen cooling pipeline 14, a hydrogen shut-off valve 15, a low-density phase change cooling screen 16, and a low-density medium... 17. First S-type capillary connector; 18. Low-density medium shut-off valve; 19. Low-density medium vaporizer; 20. High-density phase change cooling screen; 21. High-density medium; 22. Second S-type capillary connector; 23. High-density medium shut-off valve; 24. High-density medium vaporizer; 25. Low-density medium filling pipeline; 26. Low-density medium tank; 27. Low-density medium filling valve; 28. High-density medium filling pipeline; 29. ​​High-density medium tank; 30. High-density medium filling valve; 31.

[0035] The structure and connection methods of each component will be explained in detail below.

[0036] In this invention, the liquid hydrogen supply tank 2 is equipped with a liquid hydrogen pressurization pipeline 1 and a liquid hydrogen filling pipeline 5. The bottom of the liquid hydrogen supply tank 2 is connected to the top of the liquid hydrogen supply tank 2 through the liquid hydrogen pressurization pipeline 1, which is sequentially equipped with a first liquid hydrogen shut-off valve 3 and a liquid hydrogen vaporizer 4, forming a circulation loop. That is, the liquid hydrogen pressurization pipeline 1 is sequentially connected to the bottom of the liquid hydrogen supply tank 2, the first liquid hydrogen shut-off valve 3, the liquid hydrogen vaporizer 4, and the top of the liquid hydrogen supply tank 2, so that a portion of the liquid hydrogen is vaporized and input into the liquid hydrogen supply tank 2 for pressurization, enabling the liquid hydrogen supply tank 2 to supply liquid to the liquid hydrogen filling pipeline 5.

[0037] In this invention, the liquid hydrogen refueling tank includes an outer tank 8 and an inner tank 9, which together constitute the main structure of the liquid hydrogen refueling tank. The outer tank 8 and the inner tank 9 are spaced apart, and the space between them is evacuated to form a vacuum environment. Multiple layers of simulated radiation screens are installed in the space between them. The top of the inner tank 9 is provided with an venting pipeline and a pressurizing pipeline. An venting valve 10 is installed on the venting pipeline, and a pressurizing valve 11 is installed on the pressurizing pipeline, with a connecting flange 12 installed at the top (i.e., the end). The bottom of the inner tank 9 is provided with a liquid hydrogen refueling pipeline 5 and a delivery pipeline. A fourth liquid hydrogen shut-off valve 13 is installed on the delivery pipeline, with a connecting flange 12 installed at the top (i.e., the end).

[0038] In this invention, the bottom of the liquid hydrogen supply tank 2 is connected to the bottom of the inner tank 9 via a liquid hydrogen filling pipeline 5, which is sequentially equipped with a second liquid hydrogen shut-off valve 6 and a third liquid hydrogen shut-off valve 7. That is, the liquid hydrogen filling pipeline 5 is sequentially connected to the bottom of the liquid hydrogen supply tank 2, the second liquid hydrogen shut-off valve 6, the third liquid hydrogen shut-off valve 7, the outer tank 8, and the inner tank 9, using the liquid hydrogen inside the liquid hydrogen supply tank 2 for pre-cooling and filling.

[0039] In this invention, a low-density phase change cooling screen 16 and a high-density phase change cooling screen 21 are provided in the interval area between the outer tank 8 and the inner tank 9. The top of the inner tank 9 is connected in sequence to a hydrogen shut-off valve 15, the inner channel of the low-density phase change cooling screen 16, the inner channel of the high-density phase change cooling screen 21, and the outside through a hydrogen cooling pipe 14. The low-temperature hydrogen generated during liquid hydrogen storage is used to cool and solidify the liquid medium in the low-density phase change cooling screen 16 and the high-density phase change cooling screen 21, and then the generated low-temperature hydrogen is vented. Here, "low-temperature hydrogen" refers to "low temperature" relative to the hydrogen temperature at different locations in the same pipe.

[0040] In a preferred embodiment of the present invention, the low-density phase change cooling screen 16 and the high-density medium vaporizer 22 are at the same horizontal distance from the inner tank 9. The shell of the low-density phase change cooling screen 16 is filled with a low-density medium 17, which can form heat exchange contact with the inner channel of the low-density phase change cooling screen 16. The shell of the high-density phase change cooling screen 21 is filled with a high-density medium 22, which can form heat exchange contact with the inner channel of the high-density phase change cooling screen 21. Specifically, the low-density medium 17 can be liquid nitrogen, and the high-density medium 22 can be liquid argon.

[0041] In this invention, the front end of the low-density phase change cooling screen 16 is connected to the low-density medium tank 27 via a low-density medium filling pipeline 26 equipped with a low-density medium filling valve 28, allowing liquid low-density medium 17 to be filled into the low-density phase change cooling screen 16. The bottom of the low-density phase change cooling screen 16 is sequentially connected to a first S-type capillary connector 18, a low-density medium shut-off valve 19, and a low-density medium vaporizer 20, with the outlet of the low-density medium vaporizer 20 located inside the inner tank 9. The liquid low-density medium 17 can enter the inner tank 9 and vaporize under the capillary force of the first S-type capillary connector 18, maintaining a slight positive pressure in the inner tank 9 and preventing external air from entering.

[0042] In a preferred embodiment of the present invention, metal fins are provided on the outer side of the inner channel of the low-density phase change cooling screen 16 to enhance the thermal conductivity of low-temperature hydrogen to the low-density medium 17.

[0043] As a preferred embodiment of the present invention, the low-density medium vaporizer 20 is a one-way passage, which can only introduce the medium into the inner tank 9, that is, it has the characteristic of one-way outflow of the medium, preventing liquid hydrogen from entering.

[0044] In a preferred embodiment of the present invention, the outer material of the first S-shaped capillary connector 18 is a low thermal conductivity material, and the interior is filled with a porous material. This ensures that the low-density medium 17 can smoothly enter the inner tank 9 while preventing thermal conduction from damaging the insulation capacity of the liquid hydrogen refueling tank. Here, "low thermal conductivity material" refers to a low thermal conductivity material in the conventional sense in the art, but it can also be specified as needed.

[0045] In this invention, the front end of the high-density phase change cooling screen 21 is connected to the high-density medium tank 30 via a high-density medium filling pipeline 29 equipped with a high-density medium filling valve 31, allowing liquid high-density medium 22 to be filled into the high-density phase change cooling screen 21. The bottom of the high-density phase change cooling screen 21 is sequentially connected to a second S-type capillary connector 23, a high-density medium shut-off valve 24, and a high-density medium vaporizer 25, with the outlet of the high-density medium vaporizer 25 located inside the inner tank 9. The liquid high-density medium 22 can enter the inner tank 9 under the capillary force of the second S-type capillary connector 23 for vaporization, maintaining a slight positive pressure in the inner tank 9 and preventing external air from entering.

[0046] In a preferred embodiment of the present invention, metal fins are provided on the outer side of the inner channel of the high-density phase change cooling screen 21 to enhance the thermal conductivity of low-temperature hydrogen to the high-density medium 22.

[0047] As a preferred embodiment of the present invention, the high-density medium vaporizer 25 is a one-way passage, which can only introduce medium into the inner tank 9, that is, it has the characteristic of one-way outflow of medium, preventing liquid hydrogen from entering.

[0048] In a preferred embodiment of the present invention, the outer material of the second S-shaped capillary connector 23 is a low thermal conductivity material, and the interior is filled with a porous material. This ensures that the high-density medium 22 can smoothly enter the inner tank 9 while preventing thermal conduction from damaging the insulation capacity of the liquid hydrogen refueling tank. Here, "low thermal conductivity material" refers to a low thermal conductivity material in the conventional sense in the art, but it can also be specified as needed.

[0049] In a preferred embodiment of the present invention, the hydrogen shut-off valve 15, the first S-type capillary connector 18, the low-density medium shut-off valve 19, the low-density medium vaporizer 20, the second S-type capillary connector 23, the high-density medium shut-off valve 24, and the high-density medium vaporizer 25 are all located within the interval area, while the vent valve 10, the pressure boosting valve 11, the connecting flange 12, the low-density medium tank 27, the low-density medium filling valve 28, the high-density medium tank 30, and the high-density medium filling valve 31 are all located outside the liquid hydrogen filling tank.

[0050] In a preferred embodiment of the present invention, the liquid hydrogen pressurization pipeline 1, the liquid hydrogen filling pipeline 5, the hydrogen cooling pipeline 14 and other components are all provided with heat insulation material to prevent heat leakage.

[0051] Utilizing the aforementioned soft-cooled liquid hydrogen refueling system, this invention also provides a control method, the specific details of which (i.e., operating principle) are as follows:

[0052] Assume all valves are closed and all devices are stopped.

[0053] (1) Refueling stage: Complete the refueling of low-density medium, high-density medium and liquid hydrogen.

[0054] Open the low-density medium filling valve 28, and the low-density medium 17 from the low-density medium tank 27 enters the low-density phase change cooling screen 16 through the low-density medium filling pipeline 26. After the low-density medium 17 in the low-density phase change cooling screen 16 reaches the set liquid level, stop filling and close the low-density medium filling valve 28.

[0055] Open the high-density medium filling valve 31, and the high-density medium 22 from the high-density medium tank 30 enters the high-density phase change cooling screen 21 through the high-density medium filling pipeline 29. After the high-density medium 22 in the high-density phase change cooling screen 21 reaches the set liquid level, stop filling and close the high-density medium filling valve 31.

[0056] Open the first liquid hydrogen shut-off valve 3. Part of the liquid hydrogen at the bottom of the liquid hydrogen supply tank 2 enters the liquid hydrogen pressurization pipeline 1, and then enters the liquid hydrogen vaporizer 4 through the first liquid hydrogen shut-off valve 3 to absorb heat and vaporize. Finally, it enters the gas phase space at the top of the liquid hydrogen supply tank 2 for pressurization, enabling the liquid hydrogen supply tank 2 to supply liquid to the outside.

[0057] Open the second liquid hydrogen shut-off valve 6, the third liquid hydrogen shut-off valve 7, and the vent valve 10. Liquid hydrogen from the liquid hydrogen supply tank 2 enters the liquid hydrogen filling pipeline 5, flowing sequentially through the second liquid hydrogen shut-off valve 6, the third liquid hydrogen shut-off valve 7, the outer tank 8, and the inner tank 9, pre-cooling the liquid hydrogen filling pipeline 5 and the inner tank 9. Finally, it is vented through the vent valve 10. After pre-cooling is complete, continue to add liquid hydrogen to the inner tank 9 through the liquid hydrogen filling pipeline 5 until the set liquid level of the inner tank 9 is reached. The filling is then completed, and the first liquid hydrogen shut-off valve 3, the second liquid hydrogen shut-off valve 6, and the third liquid hydrogen shut-off valve 7 are closed.

[0058] (2) Storage stage: Liquid hydrogen is added and is in a long-term storage state.

[0059] Open the hydrogen shut-off valve 15 and close the vent valve 10. The low-temperature hydrogen generated inside the inner tank 9 enters the hydrogen cooling pipe 14 through the hydrogen shut-off valve 15. First, it enters the inner channel of the low-density phase change cooling screen 16, causing the low-density medium 17 inside the low-density phase change cooling screen 16 to solidify. Then, it enters the inner channel of the high-density phase change cooling screen 21, causing the high-density medium 22 inside the high-density phase change cooling screen 21 to solidify, thus realizing the recovery of cold energy from the low-temperature gas. Finally, it is vented through the hydrogen cooling pipe 14. The solidified low-density phase change cooling screen 16 and high-density phase change cooling screen 21 further enhance the insulation capacity between the outer tank 8 and the inner tank 9.

[0060] (3) Idle stage: The liquid hydrogen in the inner tank 9 has been emptied and the interior is in an idle stage.

[0061] Open the high-density medium shut-off valve 24. The solid high-density medium 22 inside the high-density phase change cooling screen 21 slowly absorbs external heat and partially liquefies, prolonging the time that the inner tank 9 maintains a low temperature. The liquefied high-density medium 22 enters the second S-type capillary connector 23, and under the action of capillary force, it passes through the high-density medium shut-off valve 24 to reach the high-density medium vaporizer 25. After absorbing external heat, it gradually vaporizes and flows into the inner tank 9.

[0062] Open the low-density medium shut-off valve 19. The solid low-density medium 17 inside the low-density phase change cooling screen 16 slowly absorbs external heat and partially liquefies, prolonging the time that the inner tank 9 maintains a low-temperature state. The liquefied low-density medium 17 enters the first S-type capillary connector 18, and under the action of capillary force, it passes through the low-density medium shut-off valve 19 to reach the low-density medium vaporizer 20. After absorbing external heat, it gradually vaporizes and flows into the inner tank 9.

[0063] After vaporization, the low-density medium 17 and the high-density medium 22 form a gradient distribution in the inner tank 9 due to their density difference and maintain a slight positive pressure. They are continuously and slowly vented through the vent valve 10. The first S-type capillary connector 18 and the second S-type capillary connector 23 can automatically extend the time of the liquid low-density medium 17 and the liquid high-density medium 22, so that the inner tank 9 can maintain a low temperature and high purity state for a longer period of time, reducing the replacement and pre-cooling time required for subsequent liquid hydrogen refueling.

[0064] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A soft-shield liquid hydrogen fuelling system, characterised in that, Includes a liquid hydrogen supply tank (2) and a liquid hydrogen filling tank; The liquid hydrogen supply tank (2) is equipped with a liquid hydrogen pressurization pipeline (1) and a liquid hydrogen filling pipeline (5). The bottom of the liquid hydrogen supply tank (2) is connected to the top of the liquid hydrogen supply tank (2) through the liquid hydrogen pressurization pipeline (1), which is equipped with a first liquid hydrogen shut-off valve (3) and a liquid hydrogen vaporizer (4) in sequence, forming a circulation loop. The liquid hydrogen filling tank includes an outer tank (8) and an inner tank (9), which are nested at intervals and the interval between them is a vacuum environment. The bottom of the liquid hydrogen supply tank (2) is connected to the top of the liquid hydrogen supply tank (2) through the liquid hydrogen pressurization pipeline (1) and the liquid hydrogen filling pipeline (5). A liquid hydrogen filling pipeline (5) with a second liquid hydrogen shut-off valve (6) and a third liquid hydrogen shut-off valve (7) is connected to the bottom of the inner tank (9); the top of the inner tank (9) is connected to a drain pipeline with a drain valve (10), a pressurization pipeline with a pressurization valve (11), and a hydrogen cooling pipeline (14), and the bottom is connected to a delivery pipeline with a fourth liquid hydrogen shut-off valve (13). The ends of the pressurization pipeline and the delivery pipeline are respectively provided with connecting flanges (12); a low-density phase change cooling screen (1) is provided in the interval area. 6) and the high-density phase change cooling screen (21), the top of the inner tank (9) is connected in sequence to the hydrogen shut-off valve (15), the inner channel of the low-density phase change cooling screen (16), the inner channel of the high-density phase change cooling screen (21) and the outside through the hydrogen cooling pipe (14); the front end of the low-density phase change cooling screen (16) is connected to the low-density medium tank (27) through the low-density medium filling pipe (26) equipped with the low-density medium filling valve (28), and the bottom is connected in sequence to the first S-type capillary connector (18) and the low-density medium The front end of the high-density phase change cooling screen (21) is connected to the high-density medium tank (30) through a high-density medium filling pipeline (29) equipped with a high-density medium filling valve (31), and the bottom is connected in sequence to the second S-type capillary connector (23), the high-density medium stop valve (24), and the high-density medium vaporizer (25); the outlet ends of the low-density medium vaporizer (20) and the high-density medium vaporizer (25) are both located inside the inner tank (9).

2. The soft-cooled screen liquid hydrogen refueling system according to claim 1, characterized in that, The low-density phase change cooling screen (16) and the high-density medium vaporizer (22) are at the same horizontal distance from the inner tank (9).

3. The soft-cooled screen liquid hydrogen refueling system according to claim 1, characterized in that, The hydrogen shut-off valve (15), the first S-type capillary connector (18), the low-density medium shut-off valve (19), the low-density medium vaporizer (20), the second S-type capillary connector (23), the high-density medium shut-off valve (24), and the high-density medium vaporizer (25) are all located within the interval area. The vent valve (10), the pressure boosting valve (11), the connecting flange (12), the low-density medium tank (27), the low-density medium filling valve (28), the high-density medium tank (30), and the high-density medium filling valve (31) are all located outside the liquid hydrogen filling tank.

4. The soft-cooled screen liquid hydrogen refueling system according to claim 1, characterized in that, The shell of the low-density phase change cold screen (16) is filled with a low-density medium (17), which can form a heat exchange contact with the inner channel of the low-density phase change cold screen (16); the shell of the high-density phase change cold screen (21) is filled with a high-density medium (22), which can form a heat exchange contact with the inner channel of the high-density phase change cold screen (21).

5. The soft-cooled screen liquid hydrogen refueling system according to claim 4, characterized in that, The low-density medium (17) is liquid nitrogen, and the high-density medium (22) is liquid argon.

6. The soft-cooled screen liquid hydrogen refueling system according to claim 1, characterized in that, Both the low-density medium vaporizer (20) and the high-density medium vaporizer (25) are unidirectional passages, allowing medium to be introduced into the inner tank (9).

7. The soft-cooled screen liquid hydrogen refueling system according to claim 1, characterized in that, The liquid hydrogen pressurization pipeline (1), liquid hydrogen filling pipeline (5), and hydrogen cooling pipeline (14) are all wrapped with heat insulation material.

8. The soft-cooled screen liquid hydrogen refueling system according to claim 1, characterized in that, The first S-type capillary connector (18) and the second S-type capillary connector (23) are both wrapped with low thermal conductivity material on the outside and filled with porous material on the inside.

9. The soft-cooled screen liquid hydrogen refueling system according to claim 1, characterized in that, Both the low-density phase change cooling screen (16) and the high-density phase change cooling screen (21) have metal fins on the outer side of their inner channels to enhance heat conduction.

10. A control method for the soft-cooled screen liquid hydrogen refueling system according to any one of claims 1 to 9, characterized in that, Specifically as follows: All valves are closed, and all equipment is stopped. S1: Open the low-density medium filling valve (28), and the low-density medium (17) from the low-density medium tank (27) enters the low-density phase change cooling screen (16) through the low-density medium filling pipeline (26); after the low-density medium (17) in the low-density phase change cooling screen (16) reaches the set liquid level, stop filling and close the low-density medium filling valve (28); Open the high-density medium filling valve (31), and the high-density medium (22) from the high-density medium tank (30) enters the high-density phase change cooling screen (21) through the high-density medium filling pipeline (29); after the high-density medium (22) in the high-density phase change cooling screen (21) reaches the set liquid level, stop filling and close the high-density medium filling valve (31); Open the first liquid hydrogen shut-off valve (3); part of the liquid hydrogen at the bottom of the liquid hydrogen supply tank (2) enters the liquid hydrogen pressurization pipeline (1), and then enters the liquid hydrogen vaporizer (4) through the first liquid hydrogen shut-off valve (3) to absorb heat and vaporize, and finally enters the gas phase space at the top of the liquid hydrogen supply tank (2) to pressurize, so that the liquid hydrogen supply tank (2) has the ability to supply liquid to the outside. Open the second liquid hydrogen shut-off valve (6), the third liquid hydrogen shut-off valve (7), and the vent valve (10); liquid hydrogen from the liquid hydrogen supply tank (2) enters the liquid hydrogen filling pipeline (5), flows through the second liquid hydrogen shut-off valve (6), the third liquid hydrogen shut-off valve (7), the outer tank (8), and the inner tank (9) in sequence, pre-cools the liquid hydrogen filling pipeline (5) and the inner tank (9), and finally vents through the vent valve (10); after the pre-cooling is completed, continue to add liquid hydrogen to the inner tank (9) through the liquid hydrogen filling pipeline (5) until the set liquid level of the inner tank (9) is reached, the filling is completed, and the first liquid hydrogen shut-off valve (3), the second liquid hydrogen shut-off valve (6), and the third liquid hydrogen shut-off valve (7) are closed; S2: Open the hydrogen shut-off valve (15) and close the vent valve (10); the low-temperature hydrogen generated inside the inner tank (9) enters the hydrogen cooling pipeline (14) through the hydrogen shut-off valve (15), first enters the inner channel of the low-density phase change cold screen (16), causing the low-density medium (17) inside the low-density phase change cold screen (16) to solidify, and then enters the inner channel of the high-density phase change cold screen (21), causing the high-density medium (22) inside the high-density phase change cold screen (21) to solidify, realizing the recovery of cold energy of the low-temperature cold gas, and finally venting through the hydrogen cooling pipeline (14); the low-density phase change cold screen (16) and the high-density phase change cold screen (21) after the medium solidifies further enhance the insulation capacity between the outer tank (8) and the inner tank (9); S3: Open the high-density medium shut-off valve (24); the solid high-density medium (22) inside the high-density phase change cold screen (21) slowly absorbs external heat and partially liquefies, prolonging the time that the inner tank (9) maintains a low temperature state. The liquefied high-density medium (22) enters the second S-type capillary connector (23), and under the action of capillary force, it passes through the high-density medium shut-off valve (24) to reach the high-density medium vaporizer (25), absorbs external heat and gradually vaporizes and enters the inner tank (9); Open the low-density medium shut-off valve (19); the solid low-density medium (17) inside the low-density phase change cold screen (16) slowly absorbs external heat and partially liquefies, prolonging the time that the inner tank (9) maintains a low temperature state. The liquefied low-density medium (17) enters the first S-type capillary connector (18), and under the action of capillary force, it passes through the low-density medium shut-off valve (19) to reach the low-density medium vaporizer (20), absorbs external heat and gradually vaporizes and enters the inner tank (9). The vaporized low-density medium (17) and high-density medium (22) form a gradient distribution in the inner tank (9) due to their density difference and maintain a slight positive pressure. They are slowly vented through the vent valve (10). The first S-type capillary connector (18) and the second S-type capillary connector (23) can automatically extend the time of the liquid low-density medium (17) and the liquid high-density medium (22), so that the inner tank (9) can maintain a low temperature and high purity state for a longer period of time, reducing the replacement and pre-cooling time required for subsequent liquid hydrogen refueling.

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