A cascade liquid hydrogen hydrogenation station cold recovery system and method

Abstract

The application relates to a cascade liquid hydrogen hydrogenation station cold energy recovery system and method, which comprises a plurality of tee structures and a plurality of heat exchangers arranged in a closed cold box, and further comprises a hydrogen flow path and a plurality of working medium flow paths, nitrogen, carbon dioxide, ethylene glycol solution, water and the like are selected as cold energy recovery and cold storage working medium, the cold energy recovery in the liquid hydrogen gasification process is realized in a cascade mode according to a temperature gradient, effective cold energy reuse can be realized, the problems in the air cooling and water cooling gasification process of liquid hydrogen are avoided, and the economy of the liquid hydrogen hydrogenation station is improved.

Description

Technical Field

[0001] This invention relates to the field of liquid hydrogen cold energy recovery technology, and in particular to a cascaded liquid hydrogen refueling station cold energy recovery system and method. Background Technology

[0002] Due to its high hydrogen storage density, liquid hydrogen is a key development trend for hydrogen refueling stations. Simultaneously, hydrogen-powered vehicles will evolve along two paths: high-pressure hydrogen vehicles carrying high-pressure hydrogen cylinders and liquid hydrogen vehicles carrying liquid hydrogen cylinders. Liquid hydrogen at refueling stations can be directly used to refuel liquid hydrogen vehicles, or it can be heated, vaporized, and compressed for use in high-pressure hydrogen vehicles. During the heating and vaporization process, liquid hydrogen releases a significant amount of cryogenic (20K) cold energy. On one hand, liquid hydrogen's temperature is lower than the boiling and freezing points of most fluids. Conventional cooling methods, such as vaporizers using air or water as the working fluid, require large working fluid flow rates and vaporizer areas. Continuous economic investment is needed to prevent frost formation on the vaporizer surface. On the other hand, the rational recovery and utilization of this cold energy will undoubtedly improve the economics of liquid hydrogen refueling stations. For example, at 2.5 MPa, the cold energy released when liquid hydrogen is heated from 25K to 300K is as high as 4296 kJ / kg. However, the design of vaporizers is currently difficult and consumes additional energy. There is no system or method that can effectively recover and utilize the cold energy in the liquid hydrogen vaporization process of liquid hydrogen refueling stations, resulting in a serious waste of cold energy in the liquid hydrogen vaporization process of liquid hydrogen refueling stations. Summary of the Invention

[0003] Based on this, the purpose of this invention is to provide a cascaded liquid hydrogen refueling station cold energy recovery system and method, which selects nitrogen, carbon dioxide, ethylene glycol, water and other materials as cold energy recovery and cold storage working fluids to realize the recovery and reuse of cold energy during the liquid hydrogen gasification process, avoid the problems in the air-cooled and water-cooled gasification process, and improve the economic efficiency of the liquid hydrogen refueling station.

[0004] This invention provides a cascaded liquid hydrogen refueling station cold energy recovery system, comprising multiple three-way structures and multiple heat exchangers arranged in a closed cold box. The cascaded liquid hydrogen refueling station cold energy recovery system includes a hydrogen flow path and multiple working fluid flow paths, wherein the hydrogen flow path is connected to the multiple three-way structures and the multiple heat exchangers for supplying liquid hydrogen for a multi-stage heat exchange process; the working fluid flow path flows in the opposite direction to the hydrogen flow path, and the working fluid flow path is connected to one or more of the heat exchangers for utilizing the cold energy released by the liquid hydrogen during the multi-stage heat exchange process to achieve the heat exchange process of the working fluid, thereby obtaining the corresponding working fluid product.

[0005] In one embodiment of the present invention, the cascaded liquid hydrogen refueling station cold energy recovery system includes a first three-way structure, a second three-way structure, a first heat exchanger, a second heat exchanger, a third heat exchanger, and a throttling valve, and further includes a liquid hydrogen interface, a hydrogen interface, a first working fluid interface, a second working fluid interface, a third working fluid interface, a first interface, a second interface, and a third interface; the plurality of working fluid flow paths include a first working fluid flow path, a second working fluid flow path, and a third working fluid flow path;

[0006] The hydrogen flow path is sequentially connected to the liquid hydrogen interface, the first three-way structure, the first heat exchanger, the second three-way structure, the second heat exchanger, the third heat exchanger, and the hydrogen interface. Liquid hydrogen enters the hydrogen flow path and undergoes a multi-stage heat exchange process to form hydrogen gas, which is then recycled through the hydrogen interface.

[0007] The first working fluid flow path is sequentially connected to the first working fluid interface, the third heat exchanger, the second heat exchanger, the first heat exchanger, the throttle valve, and the first interface. After the first working fluid enters the first working fluid flow path for heat exchange, a first working fluid product is obtained. The first working fluid product is recycled through the first interface.

[0008] The second working fluid flow path is sequentially connected to the second working fluid interface, the third heat exchanger, the second heat exchanger, and the second interface. After the second working fluid enters the second working fluid flow path for heat exchange, a second working fluid product is obtained. The second working fluid product is recycled through the second interface.

[0009] The third working fluid flow path is sequentially connected to the third working fluid interface, the third heat exchanger, and the third interface. After the third working fluid enters the third working fluid flow path and undergoes a heat exchange process, a third working fluid product is obtained. The third working fluid product is recycled through the third interface.

[0010] In one embodiment of the present invention, the first three-way valve has a first inlet, a second inlet, and a first outlet, and the second three-way valve has a third inlet, a second outlet, and a third outlet. The cascaded liquid hydrogen refueling station cold energy recovery system further includes a reflux hydrogen flow path, which is sequentially connected to the second outlet of the second three-way valve and the first inlet of the first three-way valve. This reflux hydrogen flow path is used to introduce a portion of reflux hydrogen into the hydrogen flow path to increase the hydrogen temperature in the hydrogen flow path and prevent the working fluid from solidifying and clogging the heat exchanger channel due to the liquid hydrogen temperature being lower than the working fluid's freezing point.

[0011] In one embodiment of the present invention, the first heat exchanger is a two-flow heat exchanger, the second heat exchanger is a three-flow heat exchanger, and the third heat exchanger is a four-flow heat exchanger.

[0012] In one embodiment of the present invention, the first working medium is nitrogen, the first working medium interface is connected to a nitrogen cylinder group, and the first interface is connected to a liquid nitrogen storage tank; the second working medium is carbon dioxide, the second working medium interface is connected to a carbon dioxide cylinder group, and the second interface is connected to a liquid carbon dioxide storage tank or a dry ice maker; the third working medium is ethylene glycol or water, the third working medium interface is connected to a high-temperature solution tank, and the third interface is connected to a low-temperature solution tank.

[0013] In one embodiment of the present invention, the pressure of the first working fluid in the first working fluid flow path is ≥2 bara, the pressure of the second working fluid in the second working fluid flow path is ≥6 bara, and the pressure of the third working fluid in the third working fluid flow path is >1 bara.

[0014] In another aspect, the present invention also provides a method for recovering cold energy in a cascaded liquid hydrogen refueling station, comprising the following steps:

[0015] S1. Liquid hydrogen is introduced into the hydrogen flow path. The liquid hydrogen flows through the first three-way structure and mixes with the hydrogen gas that flows back into the first three-way structure. Then it flows through the first heat exchanger, the second three-way structure, the second heat exchanger and the third heat exchanger in sequence to form hydrogen gas. The hydrogen gas is discharged through the hydrogen gas interface.

[0016] S2. The first working fluid is introduced into the first working fluid flow path. The first working fluid flows through the third heat exchanger, the second heat exchanger, the first heat exchanger and the throttle valve in sequence to obtain the first working fluid product. The first working fluid product is discharged through the first port.

[0017] S3. The second working fluid is introduced into the second working fluid flow path. After the second working fluid flows through the third heat exchanger and the second heat exchanger in sequence, the second working fluid product is obtained. The second working fluid product is discharged through the second port.

[0018] S4. The third working fluid is introduced into the third working fluid flow path. After the third working fluid flows through the third heat exchanger, the third working fluid product is obtained. The third working fluid product is discharged through the third interface.

[0019] In one embodiment of the present invention, the first heat exchanger is a two-flow heat exchanger, the second heat exchanger is a three-flow heat exchanger, and the third heat exchanger is a four-flow heat exchanger.

[0020] In one embodiment of the present invention, in step S2, the first working medium interface is connected to a nitrogen cylinder group to introduce nitrogen into the first working medium flow path through the nitrogen cylinder group, and the first interface is connected to a liquid nitrogen storage tank to recover liquid nitrogen.

[0021] In one embodiment of the present invention, in step S3, the second working medium interface is connected to a carbon dioxide cylinder group to introduce carbon dioxide into the second working medium flow path via the carbon dioxide cylinder group, and the second interface is connected to a liquid carbon dioxide storage tank or a dry ice maker to recover liquid carbon dioxide.

[0022] In one embodiment of the present invention, in step S4, the third working medium interface is connected to a high-temperature solution tank to allow ethylene glycol or water to be introduced into the third working medium flow path via the high-temperature solution tank, and the third interface is connected to a low-temperature solution tank to recover the ethylene glycol solution or water.

[0023] In one embodiment of the present invention, in step S2, the pressure of the first working fluid introduced into the first working fluid flow path is ≥2 bara; in step S3, the pressure of the second working fluid introduced into the second working fluid flow path is ≥6 bara; and in step S4, the pressure of the third working fluid introduced into the third working fluid flow path is >1 bara.

[0024] This invention addresses the issues of cold energy waste during liquid hydrogen vaporization, the difficulty in vaporizer design, and additional energy consumption. Based on various application scenarios of liquid hydrogen cold energy, the gradient utilization of hydrogen cold energy, construction costs, and cold energy recovery and reuse, it proposes a cascaded liquid hydrogen refueling station cold energy recovery system and method. Nitrogen, carbon dioxide, ethylene glycol solution, and water are selected as cold energy recovery and storage media to achieve the recovery of liquid hydrogen cold energy during vaporization and enable effective cold energy reuse. This avoids the problems encountered in air-cooled and water-cooled vaporization processes, improving the economic efficiency of liquid hydrogen refueling stations.

[0025] The cascaded liquid hydrogen refueling station cold energy recovery system of the present invention can recover the cold energy generated during the liquid hydrogen vaporization process of the liquid hydrogen refueling station in a cascade manner according to the temperature gradient. Moreover, it does not require nitrogen or carbon dioxide compressors and corresponding site and electricity input. The overall structure is simple, the cost is low, and the cold energy recovery efficiency is high, which has broad application prospects.

[0026] The further objects and advantages of the invention will become fully apparent from the following description and accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the cascaded liquid hydrogen refueling station cold energy recovery system according to a preferred embodiment of the present invention, wherein the arrows indicate the direction of fluid flow.

[0028] Reference numerals in the attached diagrams: Cascaded liquid hydrogen refueling station cold energy recovery system 100; Enclosed cold box 10; First three-way structure 21; First inlet 211; Second inlet 212; First outlet 213; Second three-way structure 22; Third inlet 221; Second outlet 222; Third outlet 223; First heat exchanger 31; Second heat exchanger 32; Third heat exchanger 33; Throttling valve 34; Liquid hydrogen interface 41; Hydrogen interface 42; First working fluid interface 43; Second working fluid interface 44; Third working fluid interface 45; First interface 46; Second interface 47; Third interface 48; First working fluid flow path 51; Second working fluid flow path 52; Third working fluid flow path 53; Return hydrogen flow path 54; Hydrogen flow path 55. Detailed Implementation

[0029] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0030] Those skilled in the art should understand that, in the disclosure of this invention, the terms "vertical," "horizontal," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0031] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0032] 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 communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] like Figure 1As shown, the specific structure of a cascaded liquid hydrogen refueling station cold energy recovery system 100 provided by the present invention is illustrated. Specifically, the cascaded liquid hydrogen refueling station cold energy recovery system 100 includes multiple three-way structures and multiple heat exchangers all arranged in a closed cold box 10. The cascaded liquid hydrogen refueling station cold energy recovery system 100 includes a hydrogen flow path 55 and multiple working fluid flow paths, wherein the hydrogen flow path 55 is connected to multiple three-way structures and multiple heat exchangers for supplying liquid hydrogen for a multi-stage heat exchange process; the working fluid flow path flows in the opposite direction to the hydrogen flow path 55, and the working fluid flow path is connected to one or more of the heat exchangers for utilizing the cold energy released by the liquid hydrogen during the multi-stage heat exchange process to achieve the heat exchange process of the working fluid, thereby obtaining the corresponding working fluid product.

[0034] More specifically, the cascaded liquid hydrogen refueling station cold energy recovery system 100 adopts two three-way structures, three heat exchangers and one throttle valve 34. The entire structure is arranged in a closed cold box 10 (vacuum container). The inlet and outlet of the four working fluids pass through the closed cold box 10 and are connected to the outside.

[0035] The cascaded liquid hydrogen refueling station cold energy recovery system 100 includes a first three-way structure 21, a second three-way structure 22, a first heat exchanger 31, a second heat exchanger 32, a third heat exchanger 33, and a throttle valve 34. It also includes a liquid hydrogen interface 41, a hydrogen interface 42, a first working fluid interface 43, a second working fluid interface 44, a third working fluid interface 45, a first interface 46, a second interface 47, and a third interface 48. The multiple working fluid flow paths include a first working fluid flow path 51, a second working fluid flow path 52, and a third working fluid flow path 53.

[0036] The hydrogen flow path 55 is sequentially connected to the liquid hydrogen interface 41, the first three-way structure 21, the first heat exchanger 31, the second three-way structure 22, the second heat exchanger 32, the third heat exchanger 33, and the hydrogen interface 42. Liquid hydrogen enters the hydrogen flow path 55 and undergoes a multi-stage heat exchange process to form hydrogen gas, which is then recycled through the hydrogen interface 42.

[0037] The first working fluid flow path 51 is sequentially connected to the first working fluid interface 43, the third heat exchanger 33, the second heat exchanger 32, the first heat exchanger 31, the throttle valve 34, and the first interface 46. After the first working fluid enters the first working fluid flow path 51 for heat exchange, a first working fluid product is obtained. The first working fluid product is recycled through the first interface 46.

[0038] The second working fluid flow path 52 is sequentially connected to the second working fluid interface 44, the third heat exchanger 33, the second heat exchanger 32 and the second interface 47. After the second working fluid enters the second working fluid flow path 52 for heat exchange, a second working fluid product is obtained. The second working fluid product is recycled through the second interface 47.

[0039] The third working fluid flow path 53 is sequentially connected to the third working fluid interface 45, the third heat exchanger 33, and the third interface 48. After the third working fluid enters the third working fluid flow path 53 for heat exchange, a third working fluid product is obtained. The third working fluid product is recycled through the third interface 48.

[0040] Specifically, the first three-way valve has a first inlet 211, a second inlet 212, and a first outlet 213, and the second three-way valve has a third inlet 221, a second outlet 222, and a third outlet 223. The cascaded liquid hydrogen refueling station cold energy recovery system 100 further includes a reflux hydrogen flow path 54, which is sequentially connected to the second outlet 222 of the second three-way valve and the first inlet 211 of the first three-way valve. It is used to introduce a portion of reflux hydrogen into the hydrogen flow path 55 to increase the hydrogen temperature in the hydrogen flow path 55 and prevent the working fluid from solidifying and clogging the heat exchanger flow channel due to the temperature in the hydrogen flow path 55 being lower than the freezing point of the working fluid.

[0041] In other words, since the temperature of liquid hydrogen is lower than that of liquid nitrogen, in order to avoid nitrogen solidification and blockage of the heat exchanger flow channel, the present invention designs the backflow hydrogen flow path 54, so that part of the hydrogen gas backflows and mixes with the liquid hydrogen, increasing the hydrogen flow temperature, thereby avoiding nitrogen solidification and blockage of the heat exchanger flow channel.

[0042] It is understood that the present invention adopts two three-way structures and sets the two three-way structures on both sides of the first heat exchanger 31 respectively, so as to realize the construction of the hydrogen flow path 55 and the return hydrogen flow path 54 with a relatively simple structure, which is beneficial to simplify the structure of the cascaded liquid hydrogen refueling station cold energy recovery system 100 and reduce the overall volume.

[0043] Understandably, since liquid hydrogen has a temperature of only about 20K, it is necessary to select a suitable working medium for heat exchange with hydrogen. The selected working medium should meet the following requirements: 1. Non-toxic and harmless; 2. Sufficiently low melting and boiling points, large specific heat capacity, and non-freezing; 3. Due to the limited area of ​​hydrogen refueling stations, the required supporting facilities should have low construction costs and occupy a small area; 4. Easy to exchange heat with other working media.

[0044] Based on this, the present invention uses nitrogen, carbon dioxide, ethylene glycol or water as the working medium for cold energy recovery and cold storage of liquid hydrogen. These working media can meet the aforementioned requirements well, realize the recovery of cold energy from liquid hydrogen vaporization, and enable effective cold energy reuse.

[0045] Specifically, the first working medium selected in this invention is nitrogen, the first working medium interface 43 is connected to a nitrogen cylinder group, and the first interface 46 is connected to a liquid nitrogen storage tank; the second working medium is carbon dioxide, the second working medium interface 44 is connected to a carbon dioxide cylinder group, and the second interface 47 is connected to a liquid carbon dioxide storage tank or a dry ice maker; the third working medium is ethylene glycol or water, the third working medium interface 45 is connected to a high-temperature solution tank, and the third interface 48 is connected to a low-temperature solution tank.

[0046] It is understandable that the flow directions of the four fluids are as follows: Figure 1 The flow proceeds in the direction indicated by the arrow:

[0047] Liquid hydrogen: Liquid hydrogen passes through the first three-way structure 21 and mixes with the return hydrogen entering the first three-way structure 21 to form hydrogen gas A. It then enters the first heat exchanger 31 and becomes hydrogen gas B. Hydrogen gas B enters the second three-way structure 22. One stream splits into return hydrogen gas entering the first three-way structure 21, while the other stream, called hydrogen gas C, flows into the second heat exchanger 32 and becomes hydrogen gas D. Hydrogen gas D flows through the third heat exchanger 33 and becomes hydrogen gas E at near room temperature. Hydrogen gas E enters the hydrogen storage tank or hydrogen compressor through the hydrogen port 42 for recycling.

[0048] Nitrogen gas: Nitrogen gas passes sequentially through the third heat exchanger 33, the second heat exchanger 32, the first heat exchanger 31 and the throttle valve 34, and its name changes sequentially from nitrogen gas A to nitrogen gas B, nitrogen gas C, liquid nitrogen A and liquid nitrogen B. Liquid nitrogen B enters the liquid nitrogen storage tank for recovery through the first interface 46.

[0049] Carbon dioxide: Carbon dioxide passes through the third heat exchanger 33 and the second heat exchanger 32 in sequence, and its name changes from carbon dioxide A to carbon dioxide B and carbon dioxide C in sequence. Carbon dioxide C enters the liquid carbon dioxide storage tank or dry ice maker through the second interface 47 for recovery.

[0050] Solution: After passing through the third heat exchanger 33, solution A outputs solution B at a lower temperature. Solution B enters the low-temperature solution tank through the third interface 48 for recovery. The solution is ethylene glycol or water.

[0051] Nitrogen pressure: To reduce compressor investment, and given the relatively small volume of liquid hydrogen at hydrogen refueling stations (generally 500-2000 kg), the vaporization process is intermittent, meaning low compressor efficiency. Therefore, nitrogen is supplied using high-purity cylinder banks, with the pressure after depressurization set at ≥2 bara to maximize gas utilization within the cylinder banks. After throttling, the liquid nitrogen pressure is atmospheric pressure.

[0052] Carbon dioxide pressure: Carbon dioxide is supplied using a high-purity gas cylinder system. To avoid the triple point of carbon dioxide and prevent it from condensing in the heat exchanger flow channel, the pressure after depressurization can be set to ≥6 bara.

[0053] Solution pressure: >1 bara, to ensure that the solution can be driven to flow.

[0054] Hydrogen pressure: Compared to the process of first vaporizing and then compressing gaseous hydrogen using a compressor, using a liquid hydrogen pump to pressurize liquid hydrogen consumes far less energy than a compressor. Therefore, the pressure of liquid hydrogen is higher during vaporization.

[0055] Calculation example:

[0056] Calculate the quantities of liquid nitrogen, dry ice, and 50% ethylene glycol solution that can be obtained from a liquid hydrogen refueling station with a refueling capacity of 1 ton / day:

[0057] Conditions: Hydrogen pressure 25 bara, nitrogen pressure 6 bara, carbon dioxide pressure 6 bara, solution pressure 2 bara. Set the temperature of each stream according to the table below:

[0058]

[0059] The calculated flow rates of each stream are:

[0060] Flowing Stock liquid hydrogen Reflux hydrogen solution carbon dioxide nitrogen mass kg 1000 624 6070 3010 3902

[0061] As can be seen, by using the cascaded liquid hydrogen refueling station cold energy recovery system 100 and method of the present invention, 1 ton of liquid hydrogen can yield 3.9 tons of liquid nitrogen, 3 tons of dry ice, and 9 tons of cooled ethylene glycol solution. It is evident that the cascaded liquid hydrogen refueling station cold energy recovery system 100 and method of the present invention can effectively realize the recovery of cold energy from liquid hydrogen vaporization and enable effective reuse of cold energy.

[0062] Furthermore, the cold energy recovered during the liquid hydrogen vaporization process requires a reasonable heat exchange structure arrangement to ensure that the cold energy is utilized in a gradient manner. To this end, this invention selects three heat exchangers based on the type and quantity of the working fluid used. Specifically, in this embodiment, the first heat exchanger 31 is a two-flow heat exchanger, the second heat exchanger 32 is a three-flow heat exchanger, and the third heat exchanger 33 is a four-flow heat exchanger.

[0063] It should be understood that, in some embodiments of the present invention, depending on actual use, the cascaded liquid hydrogen refueling station cold energy recovery system 100 may also include four or more heat exchangers. The type of heat exchanger and the type and number of working fluid can be selected according to actual needs, and the present invention does not limit this.

[0064] In particular, in addition to the need for cooling at hydrogen refueling stations, such as pre-cooling before high-pressure hydrogen refueling, this invention also considers the following liquid hydrogen application scenarios to ensure that the recovered cooling energy is fully utilized.

[0065] Scenario 1: Cooling the liquid hydrogen tanks in liquid hydrogen vehicles to be as close as possible to the temperature of liquid hydrogen.

[0066] Liquid hydrogen tanks in liquid hydrogen vehicles require cooling after initial use or after prolonged periods of inactivity. Directly using liquid hydrogen for cooling would result in significant evaporation. Recovering and storing the cooling energy generated during liquid hydrogen vaporization for pre-cooling of the liquid hydrogen tanks in liquid hydrogen vehicles would reduce the required cooling energy and the amount of liquid hydrogen used during cooling.

[0067] Scenario 2: Directly using the cold storage medium, approximately -50℃

[0068] For conventional refrigerated trucks, cold storage media such as carbon dioxide or ethylene glycol solution can be used for refrigeration. If the cooling capacity from the liquid hydrogen vaporization process is used to produce dry ice from carbon dioxide and to cool the ethylene glycol solution, the hydrogen refueling station can become a small-scale dry ice and low-temperature ethylene glycol solution supply station.

[0069] Scenario 3: Cooling of hydrogen gas compressor and high-temperature hydrogen at hydrogen refueling station, above 0 degrees Celsius.

[0070] The compressor requires cooling for its motor during operation, and the compressed hydrogen gas also needs to be cooled to room temperature. Water cooling is a common cooling method. Providing hydrogen cooling to water can be used to cool the compressor motor and the high-temperature hydrogen gas.

[0071] Based on the above application scenarios, the gradient utilization of hydrogen cold energy, construction costs, and cold energy recovery and reuse, this invention proposes a cascaded liquid hydrogen refueling station cold energy recovery system 100 and method. Nitrogen, carbon dioxide, ethylene glycol solution, and water are selected as cold energy recovery and cold storage working fluids to realize the recovery of cold energy from liquid hydrogen vaporization and to enable effective cold energy reuse. This avoids the problems in air-cooled and water-cooled vaporization processes and improves the economic efficiency of hydrogen refueling stations.

[0072] In another aspect, the present invention also provides a method for recovering cold energy in a cascaded liquid hydrogen refueling station, comprising the following steps:

[0073] S1. Liquid hydrogen is introduced into the hydrogen flow path 55. The liquid hydrogen flows through the first three-way structure 21 and mixes with the hydrogen gas that flows back into the first three-way structure 21. Then it flows through the first heat exchanger 31, the second three-way structure 22, the second heat exchanger 32 and the third heat exchanger 33 in sequence to form hydrogen gas. The hydrogen gas is discharged through the hydrogen gas interface 42.

[0074] S2. The first working fluid is introduced into the first working fluid flow path 51. The first working fluid flows through the third heat exchanger 33, the second heat exchanger 32, the first heat exchanger 31 and the throttle valve 34 in sequence to obtain the first working fluid product. The first working fluid product is discharged through the first port 46.

[0075] S3. The second working fluid is introduced into the second working fluid flow path 52. After the second working fluid flows through the third heat exchanger 33 and the second heat exchanger 32 in sequence, the second working fluid product is obtained. The second working fluid product is discharged through the second port 47.

[0076] S4. The third working fluid is introduced into the third working fluid flow path 53. After the third working fluid flows through the third heat exchanger 33, the third working fluid product is obtained. The third working fluid product is discharged through the third interface 48.

[0077] Specifically, the first working medium used in this invention is nitrogen, the second working medium is carbon dioxide, and the third working medium is ethylene glycol or water.

[0078] Correspondingly, in step S2, the first working medium interface 43 is connected to the nitrogen cylinder group to introduce nitrogen into the first working medium flow path 51 via the nitrogen cylinder group, and the first interface 46 is connected to the liquid nitrogen storage tank to recover liquid nitrogen.

[0079] Correspondingly, in step S3, the second working medium interface 44 is connected to the carbon dioxide cylinder group to introduce carbon dioxide into the second working medium flow path 52 via the carbon dioxide cylinder group, and the second interface 47 is connected to the liquid carbon dioxide storage tank or the dry ice maker to recover liquid carbon dioxide.

[0080] Correspondingly, in step S4, the third working medium interface 45 is connected to the high-temperature solution tank to allow ethylene glycol or water to be introduced into the third working medium flow path 53 via the high-temperature solution tank, and the third interface 48 is connected to the low-temperature solution tank to recover the ethylene glycol solution or water.

[0081] Specifically, in step S2, the pressure of the first working fluid introduced into the first working fluid flow path 51 is ≥2 bara; in step S3, the pressure of the second working fluid introduced into the second working fluid flow path 52 is ≥6 bara; and in step S4, the pressure of the third working fluid introduced into the third working fluid flow path 53 is >1 bara.

[0082] In summary, this invention addresses the issues of cold energy waste during liquid hydrogen vaporization, the difficulty in vaporizer design, and additional energy consumption. Based on various application scenarios of liquid hydrogen cold energy, the gradient utilization of hydrogen cold energy, construction costs, and cold energy recovery and reuse, it proposes a cascaded liquid hydrogen refueling station cold energy recovery system and method. Nitrogen, carbon dioxide, ethylene glycol solution, and water are selected as cold energy recovery and storage media to achieve the recovery of liquid hydrogen cold energy during vaporization and enable effective cold energy reuse. This avoids the problems encountered in air-cooled and water-cooled vaporization processes, improving the economic efficiency of liquid hydrogen refueling stations.

[0083] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A cascaded liquid hydrogen refueling station cold energy recovery system, characterized in that, The cascaded liquid hydrogen refueling station cold energy recovery system includes multiple three-way structures and multiple heat exchangers, all arranged in a closed cold box. It comprises a hydrogen flow path and multiple working fluid flow paths, wherein the hydrogen flow path is connected to the multiple three-way structures and multiple heat exchangers for supplying liquid hydrogen for a multi-stage heat exchange process; the working fluid flow path flows in the opposite direction to the hydrogen flow path and is connected to one or more of the heat exchangers, for cascading recovery of the cold energy released by the liquid hydrogen during the multi-stage heat exchange process according to the temperature gradient, thereby achieving the heat exchange process of the working fluid and obtaining the corresponding working fluid product. The cascaded liquid hydrogen refueling station cold energy recovery system includes a first three-way structure, a second three-way structure, a first heat exchanger, a second heat exchanger, a third heat exchanger, and a throttling valve. It also includes a liquid hydrogen interface, a hydrogen interface, a first working fluid interface, a second working fluid interface, a third working fluid interface, a first interface, a second interface, and a third interface; the multiple working fluid flow paths include a first working fluid flow path, a second working fluid flow path, and a third working fluid flow path. The hydrogen flow path is sequentially connected to the liquid hydrogen interface, the first three-way structure, the first heat exchanger, the second three-way structure, the second heat exchanger, the third heat exchanger, and the hydrogen interface. Liquid hydrogen enters the hydrogen flow path and undergoes a multi-stage heat exchange process to form hydrogen gas, which is then recycled through the hydrogen interface. The first working fluid flow path is sequentially connected to the first working fluid interface, the third heat exchanger, the second heat exchanger, the first heat exchanger, the throttle valve, and the first interface. After the first working fluid enters the first working fluid flow path for heat exchange, a first working fluid product is obtained. The first working fluid product is recycled through the first interface. The second working fluid flow path is sequentially connected to the second working fluid interface, the third heat exchanger, the second heat exchanger, and the second interface. After the second working fluid enters the second working fluid flow path for heat exchange, a second working fluid product is obtained. The second working fluid product is recycled through the second interface. The third working fluid flow path is sequentially connected to the third working fluid interface, the third heat exchanger, and the third interface. After the third working fluid enters the third working fluid flow path and undergoes a heat exchange process, a third working fluid product is obtained. The third working fluid product is recycled through the third interface. The first three-way structure has a first inlet, a second inlet, and a first outlet; the second three-way structure has a third inlet, a second outlet, and a third outlet. The cascaded liquid hydrogen refueling station cold energy recovery system further includes a reflux hydrogen flow path. The reflux hydrogen flow path is sequentially connected to the second outlet of the second three-way structure and the first inlet of the first three-way structure. It is used to introduce a portion of reflux hydrogen into the hydrogen flow path to increase the hydrogen temperature in the hydrogen flow path and prevent the working fluid from solidifying and clogging the heat exchanger channel due to the liquid hydrogen temperature being lower than the working fluid's freezing point.

2. The cascaded liquid hydrogen refueling station cold energy recovery system according to claim 1, characterized in that, The first heat exchanger is a two-flow heat exchanger, the second heat exchanger is a three-flow heat exchanger, and the third heat exchanger is a four-flow heat exchanger.

3. The cascaded liquid hydrogen refueling station cold energy recovery system according to claim 2, characterized in that, The first working medium is nitrogen, and the first working medium interface is connected to a nitrogen cylinder group and a liquid nitrogen storage tank; the second working medium is carbon dioxide, and the second working medium interface is connected to a carbon dioxide cylinder group and a liquid carbon dioxide storage tank or a dry ice maker; the third working medium is ethylene glycol or water, and the third working medium interface is connected to a high-temperature solution tank and a low-temperature solution tank.

4. The cascaded liquid hydrogen refueling station cold energy recovery system according to claim 3, characterized in that, The pressure of the first working fluid in the first working fluid flow path is ≥2 bara, the pressure of the second working fluid in the second working fluid flow path is ≥6 bara, and the pressure of the third working fluid in the third working fluid flow path is >1 bara.

5. A method for recovering cold energy in a cascaded liquid hydrogen refueling station, applied to the cascaded liquid hydrogen refueling station cold energy recovery system as described in claim 1, characterized in that, Including the following steps: S1. Liquid hydrogen is introduced into the hydrogen flow path. The liquid hydrogen flows through the first three-way structure and mixes with the hydrogen gas that flows back into the first three-way structure. Then it flows through the first heat exchanger, the second three-way structure, the second heat exchanger and the third heat exchanger in sequence to form hydrogen gas. The hydrogen gas is discharged through the hydrogen gas interface. S2. The first working fluid is introduced into the first working fluid flow path. The first working fluid flows through the third heat exchanger, the second heat exchanger, the first heat exchanger and the throttle valve in sequence to obtain the first working fluid product. The first working fluid product is discharged through the first port. S3. The second working fluid is introduced into the second working fluid flow path. After the second working fluid flows through the third heat exchanger and the second heat exchanger in sequence, the second working fluid product is obtained. The second working fluid product is discharged through the second port. S4. The third working fluid is introduced into the third working fluid flow path. After the third working fluid flows through the third heat exchanger, the third working fluid product is obtained. The third working fluid product is discharged through the third interface.

6. The method for recovering cold energy in a cascaded liquid hydrogen refueling station according to claim 5, characterized in that, The first heat exchanger is a two-flow heat exchanger, the second heat exchanger is a three-flow heat exchanger, and the third heat exchanger is a four-flow heat exchanger.

7. The method for recovering cold energy in a cascaded liquid hydrogen refueling station according to claim 5, characterized in that, In step S2, the first working fluid interface is connected to a nitrogen cylinder group to introduce nitrogen into the first working fluid flow path via the nitrogen cylinder group, and the first interface is connected to a liquid nitrogen storage tank to recover liquid nitrogen; in step S3, the second working fluid interface is connected to a carbon dioxide cylinder group to introduce carbon dioxide into the second working fluid flow path via the carbon dioxide cylinder group, and the second interface is connected to a liquid carbon dioxide storage tank or a dry ice maker to recover liquid carbon dioxide; In step S4, the third working medium interface is connected to the high-temperature solution tank to allow ethylene glycol or water to flow into the third working medium flow path via the high-temperature solution tank, and the third interface is connected to the low-temperature solution tank to recover the ethylene glycol solution or water.

8. The method for recovering cold energy in a cascaded liquid hydrogen refueling station according to claim 5, characterized in that, In step S2, the pressure of the first working fluid flowing into the first working fluid flow path is ≥2 bara; in step S3, the pressure of the second working fluid flowing into the second working fluid flow path is ≥6 bara; in step S4, the pressure of the third working fluid flowing into the third working fluid flow path is >1 bara.

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