Ammonia cracking hydrogen production and hydrogenation device and method based on multi-stage utilization of cold energy

Abstract

The invention relates to an ammonia cracking hydrogen production and hydrogenation device and method based on cold energy multistage utilization. The method comprises an ammonia cracking hydrogen production process, a hydrogen storage process and a hydrogenation process. Liquid ammonia discharged from an ammonia storage tank is decompressed through a pressure reducing valve, enters a cold accumulation type heat exchanger to release and store a part of cold energy, then enters a cold energy multi-stage utilization module, releases residual cold energy for interstage cooling of a medium-pressure hydrogen compressor and a low-pressure hydrogen compressor, and finally enters an ammonia cracker to be cracked into nitrogen and hydrogen, and a small amount of ammonia gas is remained; high-purity hydrogen is obtained through an ammonia removal tower and a nitrogen removal tower; in the hydrogen storage process, high-purity hydrogen is further pressurized and fed into a high-pressure hydrogen storage tank after being pressurized by a medium-pressure hydrogen compressor and subjected to interstage cooling; in the hydrogenation process, high-pressure hydrogen discharged from the high-pressure hydrogen storage tank passes through the cold accumulation type heat exchanger, is cooled by stored liquid ammonia cold energy and then is supplied to hydrogen utilization equipment. Vaporization cold energy of recovered liquid ammonia is used for interstage cooling, isothermal compression is achieved, and energy consumption of a hydrogen compressor is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by ammonia cracking, and particularly to an ammonia cracking hydrogen production and hydrogenation device and method based on multi-level utilization of cold energy. Background Art

[0002] Due to problems such as high carbon emissions in hydrogen production from traditional fossil fuels, electrolytic water faces bottlenecks in cost and efficiency. Most importantly, the storage and transportation requirements for hydrogen are extremely high. Hydrogen production technology by ammonia cracking can solve the above problems. As a mature chemical product, ammonia has the advantages of high hydrogen density, easy liquefaction, and no carbon. It can be decomposed into hydrogen and nitrogen under the action of a catalyst. In addition, as a mature chemical product, the infrastructure for its production, storage, transportation, etc. is relatively complete, which can effectively reduce the construction cost of the hydrogen energy industry chain.

[0003] As an important infrastructure for hydrogen energy applications, the traditional external hydrogen supply mode of hydrogen refueling stations faces the pain points of high storage and transportation costs and high safety risks. Coupling ammonia cracking hydrogen production with a hydrogenation system can achieve the integration of in-station hydrogen production - hydrogen storage - hydrogenation. However, a large amount of cold and heat energy is not utilized during the hydrogen production and hydrogenation process, which increases the equipment cost and the difficulty of industrialization. To solve this problem, developing an ammonia cracking hydrogen production and hydrogenation system that can efficiently recover and utilize energy has become the key to promoting the commercial application of this technology and enhancing its economic efficiency.

[0004] Patent CN116241803A discloses a one-stop in-station hydrogen production and hydrogenation workstation, which designs a hydrogen production and hydrogenation station through the combination of wind power and photovoltaic, integration and miniaturization, and makes full use of heat energy through multi-stage heat exchange, but does not utilize the cold energy of liquid ammonia, resulting in waste of cold energy. Patent CN114508699A invented an integrated energy supply system for ammonia cracking hydrogen production and hydrogenation, which realizes the comprehensive and efficient supply of various energy forms such as hydrogen, electricity, heat, and cold by serving as a hydrogen carrier and an energy carrier. However, it requires additional hydrogen, and the system cannot achieve self-sufficiency in hydrogen and is complex, with high maintenance costs.

[0005] Through the above analysis, it can be seen that by optimizing the energy recovery and utilization mechanism and using a multi-stage heat exchanger to utilize the cold energy of liquid ammonia, not only can the efficiency of the system be improved, but also the operating cost can be further reduced, laying a solid foundation for the large-scale promotion of hydrogen energy technology. Summary of the Invention

[0006] Aiming at the above problems, the purpose of the present invention is to provide an ammonia cracking hydrogen production and hydrogenation device and method based on multi-level utilization of cold energy, which uses the cold energy of liquid ammonia to exchange heat with high-temperature medium-pressure hydrogen, reduces the inlet temperature of the hydrogen compressor, realizes isothermal compression, and simultaneously uses off-peak electricity to drive the ammonia cracking reaction process, stores the cold energy of liquid ammonia and hydrogen, and releases the cold energy and hydrogen during peak hours, significantly improving the energy utilization efficiency and economic efficiency of the traditional ammonia cracking hydrogen production and hydrogenation system.

[0007] To achieve the above object, the present invention adopts the following technical solutions: An ammonia cracking hydrogen production and hydrogenation device based on multi-level utilization of cold energy, comprising: an ammonia cracking hydrogen production unit, a hydrogen storage unit, and a hydrogenation unit; the ammonia cracking hydrogen production unit is respectively connected to the hydrogen storage unit and the hydrogenation unit; The ammonia cracking hydrogen production unit is used to gradually vaporize and preheat liquid ammonia by using compression heat, then crack it into nitrogen and hydrogen, and finally obtain high-purity hydrogen through separation and purification; The hydrogen storage unit is used to gradually pressurize high-purity hydrogen, cool it through the cold energy level between liquid ammonia, and then send it into a high-pressure hydrogen storage tank; The hydrogenation unit is used to supply the high-pressure hydrogen in the high-pressure hydrogen storage tank to the hydrogen-consuming equipment after cooling.

[0008] Preferably, the ammonia cracking hydrogen production unit includes an ammonia storage tank, a pressure reducing valve, a regenerative heat exchanger, a cold energy multi-level utilization module, and an ammonia cracking hydrogen production module; the cold energy multi-level utilization module includes a first low-temperature heat exchanger, a second low-temperature heat exchanger, a third low-temperature heat exchanger, and a first medium-pressure hydrogen compressor; the ammonia cracking hydrogen production module includes a first medium-temperature heat exchanger, a second medium-temperature heat exchanger, a third medium-temperature heat exchanger, an ammonia cracker, a first low-pressure cooler, a first low-pressure hydrogen compressor, a second low-pressure cooler, a second low-pressure hydrogen compressor, an ammonia removal tower, and a nitrogen removal tower; The output end of the ammonia storage tank is connected to the input end of a pressure reducing valve. The output end of the pressure reducing valve is connected to the first input end of a cold energy multi - utilization heat exchanger. The first output end of the cold energy multi - utilization heat exchanger is connected to the first input end of the first low - temperature heat exchanger in the cold energy multi - utilization module. The first output end of the first low - temperature heat exchanger is connected to the first input end of the second low - temperature heat exchanger. The first output end of the second low - temperature heat exchanger is connected to the first input end of the third low - temperature heat exchanger. The first output end of the third low - temperature heat exchanger is connected to the first input end of the first medium - temperature heat exchanger in the ammonia cracking for hydrogen production module. The first output end of the first medium - temperature heat exchanger is connected to the first input end of the second medium - temperature heat exchanger. The first output end of the second medium - temperature heat exchanger is connected to the first input end of the third medium - temperature heat exchanger. The first output end of the third medium - temperature heat exchanger is connected to the input end of an ammonia cracker. The output end of the ammonia cracker is connected to the second input end of the third medium - temperature heat exchanger. The second output end of the third medium - temperature heat exchanger is connected to the input end of the first low - pressure cooler. The output end of the first low - pressure cooler is connected to the input end of the first low - pressure hydrogen compressor. The output end of the first low - pressure hydrogen compressor is connected to the second input end of the second medium - temperature heat exchanger. The second output end of the second medium - temperature heat exchanger is connected to the input end of the second low - pressure cooler. The output end of the second low - pressure cooler is connected to the input end of the second low - pressure hydrogen compressor. The output end of the second low - pressure hydrogen compressor is connected to the second input end of the first medium - temperature heat exchanger. The second output end of the first medium - temperature heat exchanger is connected to the input end of an ammonia removal tower. The product output end of the ammonia removal tower is connected to the input end of a nitrogen removal tower, and the impurity output end of the ammonia removal tower is connected to the environment. The product output end of the nitrogen removal tower is connected to the first medium - pressure hydrogen compressor during hydrogen storage, and the impurity output end of the nitrogen removal tower is connected to the environment.

[0009] Preferably, the hydrogen storage unit and the ammonia cracking for hydrogen production unit share the first low - temperature heat exchanger, the second low - temperature heat exchanger, the third low - temperature heat exchanger and the first medium - pressure hydrogen compressor. The hydrogen storage unit further includes the second medium - pressure hydrogen compressor, the third medium - pressure hydrogen compressor and the hydrogen storage module in the cold energy multi - utilization module. The hydrogen storage module includes a diverter, a first switching valve, a second switching valve, a first high - pressure hydrogen compressor, a second high - pressure hydrogen compressor, a high - pressure cooler, a first high - pressure hydrogen storage tank and a second high - pressure hydrogen storage tank. The input end of the first medium-pressure hydrogen compressor is connected to the nitrogen removal tower in the ammonia cracking hydrogen production process. The output end of the first medium-pressure hydrogen compressor is connected to the second input end of the third low-temperature heat exchanger. The second output end of the third low-temperature heat exchanger is connected to the input end of the second medium-pressure hydrogen compressor. The output end of the second medium-pressure hydrogen compressor is connected to the second input end of the second low-temperature heat exchanger. The second output end of the second low-temperature heat exchanger is connected to the input end of the third medium-pressure hydrogen compressor. The output end of the third medium-pressure hydrogen compressor is connected to the second input end of the first low-temperature heat exchanger. The second output end of the first low-temperature heat exchanger is connected to the input end of the diverter in the hydrogen storage module. The first output end of the diverter is connected to the input end of the first switching valve. The output end of the first switching valve is connected to the input end of the first high-pressure hydrogen compressor. The output end of the first high-pressure hydrogen compressor is connected to the input end of the high-pressure cooler. The output end of the high-pressure cooler is connected to the input end of the first high-pressure hydrogen storage tank. The second output end of the diverter is connected to the input end of the second switching valve. The output end of the second switching valve is connected to the input end of the second high-pressure hydrogen compressor. The output end of the second high-pressure hydrogen compressor is connected to the input end of the second high-pressure hydrogen storage tank.

[0010] Preferably, the hydrogenation unit shares a regenerative heat exchanger with the ammonia cracking hydrogen production unit. The hydrogenation unit further includes a third switching valve, a fourth switching valve, and a hydrogen-consuming device. The input end of the third switching valve is connected to the output end of the first high-pressure hydrogen storage tank during hydrogen storage. The output end of the third switching valve is connected to the second input end of the regenerative heat exchanger. The second output end of the regenerative heat exchanger is connected to the hydrogen-consuming device. The input end of the fourth switching valve is connected to the output end of the second high-pressure hydrogen storage tank during hydrogen storage. The output end of the fourth switching valve is connected to the third input end of the regenerative heat exchanger. The third output end of the regenerative heat exchanger is connected to the hydrogen-consuming device.

[0011] Preferably, the number of hydrogen compressors and heat exchangers in the cold energy multi-stage utilization module can be multiple, not limited to 3.

[0012] The present invention also provides an ammonia cracking hydrogen production and hydrogenation method based on cold energy multi-stage utilization. This method is implemented based on an ammonia cracking hydrogen production and hydrogenation device based on cold energy multi-stage utilization as described above. The method includes an ammonia cracking hydrogen production process, a hydrogen storage process, and a hydrogenation process: The ammonia cracking hydrogen production process includes the following steps: The liquid ammonia discharged from the ammonia storage tank is depressurized by a pressure reducing valve, releases and stores cold energy to the cold energy storage heat exchanger, then successively passes through the first low-temperature heat exchanger, the second low-temperature heat exchanger and the third low-temperature heat exchanger, partially vaporizes by using the compression heat of the hydrogen compressor, and then enters the first medium-temperature heat exchanger, the second medium-temperature heat exchanger and the third medium-temperature heat exchanger to be completely vaporized and preheated. Finally, it enters the ammonia cracker to be cracked into hydrogen and nitrogen, with a small amount of ammonia remaining; the cracked products are cooled by the raw material ammonia through the third medium-temperature heat exchanger, further cooled by the first low-pressure cooler and then enter the first low-pressure hydrogen compressor for pressurization. Then, it is successively cooled by the second medium-temperature heat exchanger and the second low-pressure cooler, enters the second low-pressure hydrogen compressor for pressurization again to reach the separation pressure, and after heat exchange with the liquid ammonia through the first medium-temperature heat exchanger, it enters the ammonia removal tower to separate ammonia and the nitrogen removal tower to separate nitrogen, obtaining high-purity hydrogen.

[0013] Preferably, the hydrogen storage process includes the following steps: The high-purity hydrogen obtained after impurity separation successively passes through the first medium-pressure hydrogen compressor, the third low-temperature heat exchanger, the second medium-pressure hydrogen compressor, the second low-temperature heat exchanger, the third medium-pressure hydrogen compressor and the first low-temperature heat exchanger for pressurization and uses the cold energy level of the liquid ammonia for inter-stage cooling, enters the diverter for diversion, one stream passes through the first switching valve and is successively compressed by the first high-pressure hydrogen compressor and cooled by the high-pressure cooler and then stored in the first high-pressure hydrogen storage tank, and the other stream passes through the second switching valve and is compressed by the second high-pressure hydrogen compressor and then stored in the second high-pressure hydrogen storage tank.

[0014] Preferably, the hydrogenation process includes the following steps: The high-pressure hydrogen discharged from the first high-pressure hydrogen storage tank enters the cold energy storage heat exchanger through the third switching valve, is cooled by the stored cold energy and then supplied to the hydrogen-consuming equipment; the high-pressure hydrogen discharged from the second high-pressure hydrogen storage tank enters the cold energy storage heat exchanger through the fourth switching valve, is cooled by the cold energy of the liquid ammonia and then supplied to the hydrogen-consuming equipment.

[0015] Preferably, the components of the cracked products mainly include nitrogen and hydrogen, with a small amount of ammonia remaining. The ammonia removal tower is mainly used to remove the remaining ammonia, and the nitrogen removal tower is mainly used to purify the nitrogen in the products.

[0016] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects: 1. By configuring a multi-stage hydrogen compressor and the corresponding heat exchangers, the present invention uses the vaporization cold energy of the raw material liquid ammonia to cool the high-temperature hydrogen after compression, realizes isothermal compression, and thus reduces the energy consumption of the hydrogen compressor.

[0017] 2. The present invention uses the off-peak electricity at night to drive the ammonia cracking reaction, stores the cold energy of the liquid ammonia in the cold energy storage heat exchanger, stores the high-pressure hydrogen in the high-pressure hydrogen storage tank, releases it when hydrogen is consumed during the peak period, and at the same time uses the cold energy stored in the cold energy storage heat exchanger to cool the hydrogen, improving the hydrogenation efficiency and reducing the safety risk.

[0018] 3. The present invention couples an ammonia cracking hydrogen production system with a hydrogen refueling station, improving the system integration degree, reducing the floor area, and lowering the energy loss and the system operation and maintenance cost. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the overall structure of the ammonia cracking hydrogen production and hydrogenation device based on multi-level utilization of cold energy in an embodiment of the present invention.

[0020] Reference Signs: 1 - ammonia storage tank, 2 - pressure reducing valve, 3 - regenerative heat exchanger, 4 - cold energy multi-level utilization module, 4-1 first low-temperature heat exchanger, 4-2 second low-temperature heat exchanger, 4-3 third low-temperature heat exchanger, 4-4 first medium-pressure hydrogen compressor, 4-5 second medium-pressure hydrogen compressor, 4-6 third medium-pressure hydrogen compressor, 5 - ammonia cracking hydrogen production module, 5-1 first medium-temperature heat exchanger, 5-2 second medium-temperature heat exchanger, 5-3 third medium-temperature heat exchanger, 5-4 ammonia cracker, 5-5 first low-pressure cooler, 5-6 first low-pressure hydrogen compressor, 5-7 second low-pressure cooler, 5-8 second low-pressure hydrogen compressor, 5-9 ammonia removal tower, 5-10 nitrogen removal tower, 6 - hydrogen storage module, 6-1 diverter, 6-2 first switching valve, 6-3 second switching valve, 6-4 first high-pressure hydrogen compressor, 6-5 second high-pressure hydrogen compressor, 6-6 high-pressure cooler, 6-7 first high-pressure hydrogen storage tank, 6-8 second high-pressure hydrogen storage tank, 7 - third switching valve, 8 - fourth switching valve, 9 - hydrogen-consuming equipment. Detailed Embodiments

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of the features, steps, operations, devices, components, and / or combinations thereof.

[0023] To improve the efficiency of hydrogen production from ammonia, rationally utilize the cold energy of the raw material ammonia, and utilize the compression waste heat, the present invention provides an ammonia cracking hydrogen production and hydrogenation device and method based on multi-level utilization of cold energy, which couples ammonia cracking hydrogen production with hydrogen storage and hydrogenation to enhance the cracking reaction, and fully utilizes the cold energy of the raw material ammonia and the compression waste heat, including an ammonia cracking hydrogen production unit, a hydrogen storage unit, and a hydrogenation unit. During the low valley power period at night, the liquid ammonia discharged from the ammonia storage tank 1 is decompressed by the pressure reducing valve 2, releases cold energy to the regenerative heat exchanger 3 and stores it, and then successively passes through the first low-temperature heat exchanger 4-1, the second low-temperature heat exchanger 4-2, and the third low-temperature heat exchanger 4-3. The ammonia is partially vaporized by the compression heat of the hydrogen compressor, and then enters the first medium-temperature heat exchanger 5-1, the second medium-temperature heat exchanger 5-2, and the third medium-temperature heat exchanger 5-3 to be completely vaporized and preheated, and finally enters the ammonia cracker 5-4 to be cracked into hydrogen and nitrogen, with a small amount of ammonia remaining; the cracking products are cooled by the raw material ammonia through the third medium-temperature heat exchanger 5-3, cooled again by the first low-pressure cooler 5-5 and then enter the first low-pressure hydrogen compressor 5-6 for pressurization, and then successively pass through the second medium-temperature heat exchanger 5-2 and the second low-pressure cooler 5-7 for cooling, enter the second low-pressure hydrogen compressor 5-8 for pressurization again to reach the separation pressure, and enter the ammonia removal tower 5-9 to separate ammonia after heat exchange with the liquid ammonia through the first medium-temperature heat exchanger 5-1, and enter the nitrogen removal tower 5-10 to separate nitrogen; the high-purity hydrogen obtained after impurity separation successively passes through the first medium-pressure hydrogen compressor 4-4, the third low-temperature heat exchanger 4-3, the second medium-pressure hydrogen compressor 4-5, the second low-temperature heat exchanger 4-2, the third medium-pressure hydrogen compressor 4-6, and the first low-temperature heat exchanger 4-1, is pressurized multiple times and uses the cold energy of the liquid ammonia to cool the compression heat energy. The cooled high-pressure hydrogen enters the diverter 6-1 for diversion, and is respectively stored in the first high-pressure hydrogen storage tank 6-7 and the second high-pressure hydrogen storage tank 6-8 after compression cooling or compression. When the hydrogen-consuming terminal needs hydrogen during the peak period during the day, the high-pressure hydrogen discharged from the first high-pressure hydrogen storage tank 6-7 passes through the third switching valve 7 to the regenerative heat exchanger 3, is cooled by the cold energy stored at night and then supplied to the hydrogen-consuming equipment 9. The high-pressure hydrogen discharged from the second high-pressure hydrogen storage tank 6-8 passes through the fourth switching valve 8 to the regenerative heat exchanger 3, and is supplied to the hydrogen-consuming equipment after being cooled by the cold energy of the liquid ammonia.

[0024] In an embodiment of the present invention, an ammonia cracking hydrogen production and hydrogenation device based on multi-level utilization of cold energy is provided. In this embodiment, as Figure 1 shown, where the thick solid line represents the raw material ammonia pipeline, the thin solid line represents the hydrogen pipeline, and the short horizontal line represents the ammonia cracking product pipeline, then the system includes an ammonia cracking hydrogen production process, a hydrogen storage process, and a hydrogenation process, where: In an alternative embodiment, the ammonia cracking unit includes: an ammonia storage tank 1, a pressure reducing valve 2, a regenerative heat exchanger 3, a cold energy multi-stage utilization module 4, a first low-temperature heat exchanger 4-1, a second low-temperature heat exchanger 4-2, a third low-temperature heat exchanger 4-3, an ammonia cracking hydrogen production module 5, a first medium-temperature heat exchanger 5-1, a second medium-temperature heat exchanger 5-2, a third medium-temperature heat exchanger 5-3, an ammonia cracker 5-4, a first low-pressure cooler 5-5, a first low-pressure hydrogen compressor 5-6, a second low-pressure cooler 5-7, a second low-pressure hydrogen compressor 5-8, an ammonia removal tower 5-9, and a nitrogen removal tower 5-10.

[0025] The output end of the ammonia storage tank 1 is connected to the input end of the pressure reducing valve 2, the output end of the pressure reducing valve 2 is connected to the first input end of the regenerative heat exchanger 3, the first output end of the regenerative heat exchanger 3 is connected to the first input end of the first low-temperature heat exchanger 4-1 in the cold energy multi-stage utilization module 4, the first output end of the first low-temperature heat exchanger 4-1 is connected to the first input end of the second low-temperature heat exchanger 4-2, the first output end of the second low-temperature heat exchanger 4-2 is connected to the first input end of the third low-temperature heat exchanger 4-3, the first output end of the third low-temperature heat exchanger 4-3 is connected to the first input end of the first medium-temperature heat exchanger 5-1 in the ammonia cracking hydrogen production module 5, the first output end of the first medium-temperature heat exchanger 5-1 is connected to the first input end of the second medium-temperature heat exchanger 5-2, the first output end of the second medium-temperature heat exchanger 5-2 is connected to the first input end of the third medium-temperature heat exchanger 5-3, the first output end of the third medium-temperature heat exchanger 5-3 is connected to the input end of the ammonia cracker 5-4, the output end of the ammonia cracker 5-4 is connected to the second input end of the third medium-temperature heat exchanger 5-3, the second output end of the third medium-temperature heat exchanger 5-3 is connected to the input end of the first low-pressure cooler 5-5, the output end of the first low-pressure cooler 5-5 is connected to the input end of the first low-pressure hydrogen compressor 5-6, the output end of the first low-pressure hydrogen compressor 5-6 is connected to the second input end of the second medium-temperature heat exchanger 5-2, the second output end of the second medium-temperature heat exchanger 5-2 is connected to the input end of the second low-pressure cooler 5-7, the output end of the second low-pressure cooler 5-7 is connected to the input end of the second low-pressure hydrogen compressor 5-8, the output end of the second low-pressure hydrogen compressor 5-8 is connected to the second input end of the first medium-temperature heat exchanger 5-1, the second output end of the first medium-temperature heat exchanger 5-1 is connected to the input end of the ammonia removal tower 5-9, the product output end of the ammonia removal tower 5-9 is connected to the input end of the nitrogen removal tower 5-10, the impurity output end of the ammonia removal tower 5-9 is connected to the environment, the product output end of the nitrogen removal tower 5-10 is connected to the first medium-pressure hydrogen compressor 4-4 during hydrogen storage, and the impurity output end of the nitrogen removal tower 5-10 is connected to the environment.

[0026] In an optional embodiment, the hydrogen storage unit shares the first low-temperature heat exchanger 4-1, the second low-temperature heat exchanger 4-2, and the third low-temperature heat exchanger 4-3 with the ammonia cracking hydrogen production unit. In addition, the hydrogen storage unit further includes a first medium-pressure hydrogen compressor 4-4, a second medium-pressure hydrogen compressor 4-5, a third medium-pressure hydrogen compressor 4-6, a hydrogen storage module 6, a diverter 6-1, a first switching valve 6-2, a second switching valve 6-3, a first high-pressure hydrogen compressor 6-4, a second high-pressure hydrogen compressor 6-5, a high-pressure cooler 6-6, a first high-pressure hydrogen storage tank 6-7, and a second high-pressure hydrogen storage tank 6-8; The input end of the first medium-pressure hydrogen compressor 4-4 is connected to the nitrogen removal tower 5-10 in the ammonia cracking hydrogen production unit. The output end of the first medium-pressure hydrogen compressor 4-4 is connected to the second input end of the third low-temperature heat exchanger 4-3. The second output end of the third low-temperature heat exchanger 4-3 is connected to the input end of the second medium-pressure hydrogen compressor 4-5. The output end of the second medium-pressure hydrogen compressor 4-5 is connected to the second input end of the second low-temperature heat exchanger 4-2. The second output end of the second low-temperature heat exchanger 4-2 is connected to the input end of the third medium-pressure hydrogen compressor 4-6. The output end of the third medium-pressure hydrogen compressor 4-6 is connected to the second input end of the first low-temperature heat exchanger 4-1. The second output end of the first low-temperature heat exchanger 4-1 is connected to the input end of the diverter 6-1 in the hydrogen storage module 6. The first output end of the diverter 6-1 is connected to the input end of the first switching valve 6-2. The output end of the first switching valve 6-2 is connected to the input end of the first high-pressure hydrogen compressor 6-4. The output end of the first high-pressure hydrogen compressor 6-4 is connected to the input end of the high-pressure cooler 6-6. The output end of the high-pressure cooler 6-6 is connected to the input end of the first high-pressure hydrogen storage tank 6-7. The second output end of the diverter 6-1 is connected to the input end of the second switching valve 6-3. The output end of the second switching valve 6-3 is connected to the input end of the second high-pressure hydrogen compressor 6-5. The output end of the second high-pressure hydrogen compressor 6-5 is connected to the input end of the second high-pressure hydrogen storage tank 6-8.

[0027] In an optional embodiment, the hydrogenation unit shares the regenerative heat exchanger 3 with the ammonia cracking hydrogen production unit. In addition, the hydrogenation unit further includes a third switching valve 7, a fourth switching valve 8, and a hydrogen-consuming device 9; The input end of the third switching valve 7 is connected to the output end of the first high-pressure hydrogen storage tank 6-7. The output end of the third switching valve 7 is connected to the second input end of the regenerative heat exchanger 3. The second output end of the regenerative heat exchanger 3 is connected to the hydrogen-consuming device 9. The input end of the fourth switching valve 8 is connected to the output end of the second high-pressure hydrogen storage tank 6-8. The output end of the fourth switching valve 8 is connected to the third input end of the regenerative heat exchanger 3. The third output end of the regenerative heat exchanger 3 is connected to the hydrogen-consuming device 9.

[0028] In one embodiment of the present invention, a method for producing hydrogen by ammonia cracking and hydrogenation based on multi-stage utilization of cold energy is provided. In this embodiment, the method is implemented based on the ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy in the above embodiments. The method for the hydrogen refueling station includes the following steps: 1) The liquid ammonia discharged from the ammonia storage tank 1 is depressurized by the pressure reducing valve 2, releases and stores cold energy to the regenerative heat exchanger 3, and then successively passes through the first low-temperature heat exchanger 4-1, the second low-temperature heat exchanger 4-2, and the third low-temperature heat exchanger 4-3. The ammonia gas is partially vaporized by using the compression heat of the hydrogen compressor, and then enters the first medium-temperature heat exchanger 5-1, the second medium-temperature heat exchanger 5-2, and the third medium-temperature heat exchanger 5-3 to be completely vaporized and preheated. Finally, it enters the ammonia cracker 5-4 to be cracked into hydrogen and nitrogen, with a small amount of ammonia remaining; the cracked product is cooled by the raw material ammonia gas through the third medium-temperature heat exchanger 5-3, and after being cooled again by the first low-pressure cooler 5-5, it enters the first low-pressure hydrogen compressor 5-6 for pressurization, and then successively passes through the second medium-temperature heat exchanger 5-2 and the second low-pressure cooler 5-7 for cooling, enters the second low-pressure hydrogen compressor 5-8 for pressurization again to reach the separation pressure, and after heat exchange with the liquid ammonia through the first medium-temperature heat exchanger 5-1, it enters the ammonia removal tower 5-9 to separate ammonia gas, and enters the nitrogen removal tower 5-10 to separate nitrogen gas, obtaining high-purity hydrogen.

[0029] 2) The high-purity hydrogen obtained after impurity separation successively passes through the first medium-pressure hydrogen compressor 4-4, the third low-temperature heat exchanger 4-3, the second medium-pressure hydrogen compressor 4-5, the second low-temperature heat exchanger 4-2, the third medium-pressure hydrogen compressor 4-6, and the first low-temperature heat exchanger 4-1, is pressurized multiple times and uses the cold energy of liquid ammonia to cool the compression heat energy. The cooled high-pressure hydrogen enters the diverter 6-1 for diversion. One stream passes through the first switching valve 6-2, is compressed by the first high-pressure hydrogen compressor 6-4, cooled by the high-pressure cooler 6-6, and then enters the first high-pressure hydrogen storage tank 6-7 for storage. The other stream passes through the second switching valve 6-3, is compressed by the second high-pressure hydrogen compressor 6-5, and then enters the second high-pressure hydrogen storage tank 6-8 for storage.

[0030] 3) The high-pressure hydrogen discharged from the first high-pressure hydrogen storage tank 6-7 passes through the third switching valve 7 to the regenerative heat exchanger 3, and after being cooled by the stored cold energy, it is supplied to the hydrogen-consuming equipment 9. The high-pressure hydrogen discharged from the second high-pressure hydrogen storage tank 6-8 passes through the fourth switching valve 8 to the regenerative heat exchanger 3, and after being cooled by the cold energy of liquid ammonia, it is supplied to the hydrogen-consuming equipment.

[0031] The method provided in this embodiment is based on the above system embodiments. For the specific process and detailed content, please refer to the above embodiments and will not be elaborated here.

[0032] In summary, the present invention uses the vaporization cold energy of recycled liquid ammonia for inter-stage cooling to achieve isothermal compression and reduce the energy consumption of the hydrogen compressor. In addition, the low-valley electricity at night can be used to drive the processes of ammonia cracking for hydrogen production and hydrogen storage, store hydrogen and cold energy, and release them when hydrogen is used during peak hours, reducing the system operation cost, improving the hydrogenation efficiency and reducing the safety risk.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ammonia cracking hydrogen production and hydrogenation device based on multi - level utilization of cold energy, characterized in that, Comprising: A hydrogen production unit by ammonia cracking, a hydrogen storage unit and a hydrogen addition unit; the hydrogen production unit by ammonia cracking is respectively connected to the hydrogen storage unit and the hydrogen addition unit; The hydrogen production unit by ammonia cracking is used to vaporize and preheat liquid ammonia step by step using compression heat, then crack it into nitrogen and hydrogen, and finally obtain high-purity hydrogen through separation and purification; The hydrogen storage unit is used to pressurize high-purity hydrogen step by step, and cool it through the cold energy between liquid ammonia cold levels, and then send it into a high-pressure hydrogen storage tank; The hydrogen addition unit is used to supply the high-pressure hydrogen in the high-pressure hydrogen storage tank to hydrogen-consuming equipment after cooling.

2. The ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy as described in claim 1, wherein The hydrogen production unit by ammonia cracking includes an ammonia storage tank (1), a pressure reducing valve (2), a regenerative heat exchanger (3), a cold energy multi-stage utilization module (4), and a hydrogen production module by ammonia cracking (5); the cold energy multi-stage utilization module (4) includes a first low-temperature heat exchanger (4-1), a second low-temperature heat exchanger (4-2), a third low-temperature heat exchanger (4-3), and a first medium-pressure hydrogen compressor (4-4); the hydrogen production module by ammonia cracking (5) includes a first medium-temperature heat exchanger (5-1), a second medium-temperature heat exchanger (5-2), a third medium-temperature heat exchanger (5-3), an ammonia cracker (5-4), a first low-pressure cooler (5-5), a first low-pressure hydrogen compressor (5-6), a second low-pressure cooler (5-7), a second low-pressure hydrogen compressor (5-8), an ammonia removal tower (5-9), and a nitrogen removal tower (5-10); The output end of the ammonia storage tank (1) is connected to the input end of the pressure reducing valve (2), the output end of the pressure reducing valve (2) is connected to the first input end of the cold energy storage heat exchanger (3), the first output end of the cold energy storage heat exchanger (3) is connected to the first input end of the first low-temperature heat exchanger (4-1) in the cold energy multi-stage utilization module (4), the first output end of the first low-temperature heat exchanger (4-1) is connected to the first input end of the second low-temperature heat exchanger (4-2), the first output end of the second low-temperature heat exchanger (4-2) is connected to the first input end of the third low-temperature heat exchanger (4-3), the first output end of the third low-temperature heat exchanger (4-3) is connected to the first input end of the first medium-temperature heat exchanger (5-1) in the ammonia cracking hydrogen production module (5), the first output end of the first medium-temperature heat exchanger (5-1) is connected to the first input end of the second medium-temperature heat exchanger (5-2), the first output end of the second medium-temperature heat exchanger (5-2) is connected to the first input end of the third medium-temperature heat exchanger (5-3), the first output end of the third medium-temperature heat exchanger (5-3) is connected to the input end of the ammonia cracker (5-4), the output end of the ammonia cracker (5-4) is connected to the second input end of the third medium-temperature heat exchanger (5-3), the second output end of the third medium-temperature heat exchanger (5-3) is connected to the input end of the first low-pressure cooler (5-5), the output end of the first low-pressure cooler (5-5) is connected to the input end of the first low-pressure hydrogen compressor (5-6), the output end of the first low-pressure hydrogen compressor (5-6) is connected to the second input end of the second medium-temperature heat exchanger (5-2), the second output end of the second medium-temperature heat exchanger (5-2) is connected to the input end of the second low-pressure cooler (5-7), the output end of the second low-pressure cooler (5-7) is connected to the input end of the second low-pressure hydrogen compressor (5-8), the output end of the second low-pressure hydrogen compressor (5-8) is connected to the second input end of the first medium-temperature heat exchanger (5-1), the second output end of the first medium-temperature heat exchanger (5-1) is connected to the input end of the deammoniation tower (5-9), the product output end of the deammoniation tower (5-9) is connected to the input end of the denitrification tower (5-10), the impurity output end of the deammoniation tower (5-9) is connected to the environment, the product output end of the denitrification tower (5-10) is connected to the first medium-pressure hydrogen compressor (4-4) during hydrogen storage, and the impurity output end of the denitrification tower (5-10) is connected to the environment.

3. The ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy according to claim 2, characterized in that, The hydrogen storage unit and the ammonia cracking hydrogen production unit share the first low-temperature heat exchanger (4-1), the second low-temperature heat exchanger (4-2), the third low-temperature heat exchanger (4-3) and the first medium-pressure hydrogen compressor (4-4). The hydrogen storage unit further includes the second medium-pressure hydrogen compressor (4-5), the third medium-pressure hydrogen compressor (4-6) and the hydrogen storage module (6) of the cold energy multi-stage utilization module (4); the hydrogen storage module (6) includes a shunt (6-1), a first switching valve (6-2), a second switching valve (6-3), a first high-pressure hydrogen compressor (6-4), a second high-pressure hydrogen compressor (6-5), a high-pressure cooler (6-6), a first high-pressure hydrogen storage tank (6-7) and a second high-pressure hydrogen storage tank (6-8); The input end of the first medium-pressure hydrogen compressor (4-4) is connected to the nitrogen removal tower (5-10) in the ammonia cracking hydrogen production process. The output end of the first medium-pressure hydrogen compressor (4-4) is connected to the second input end of the third low-temperature heat exchanger (4-3). The second output end of the third low-temperature heat exchanger (4-3) is connected to the input end of the second medium-pressure hydrogen compressor (4-5). The output end of the second medium-pressure hydrogen compressor (4-5) is connected to the second input end of the second low-temperature heat exchanger (4-2). The second output end of the second low-temperature heat exchanger (4-2) is connected to the input end of the third medium-pressure hydrogen compressor (4-6). The output end of the third medium-pressure hydrogen compressor (4-6) is connected to the second input end of the first low-temperature heat exchanger (4-1). The second output end of the first low-temperature heat exchanger (4-1) is connected to the input end of the flow divider (6-1) in the hydrogen storage module (6). The first output end of the flow divider (6-1) is connected to the input end of the first switching valve (6-2). The output end of the first switching valve (6-2) is connected to the input end of the first high-pressure hydrogen compressor (6-4). The output end of the first high-pressure hydrogen compressor (6-4) is connected to the input end of the high-pressure cooler (6-6). The output end of the high-pressure cooler (6-6) is connected to the input end of the first high-pressure hydrogen storage tank (6-7). The second output end of the flow divider (6-1) is connected to the input end of the second switching valve (6-3). The output end of the second switching valve (6-3) is connected to the input end of the second high-pressure hydrogen compressor (6-5). The output end of the second high-pressure hydrogen compressor (6-5) is connected to the input end of the second high-pressure hydrogen storage tank (6-8).

4. The ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy according to claim 2, characterized in that, The hydrogenation unit shares the regenerative heat exchanger (3) with the ammonia cracking hydrogen production unit. The hydrogenation unit further includes a third switching valve (7), a fourth switching valve (8), and a hydrogen-consuming device (9). The input end of the third switching valve (7) is connected to the output end of the first high-pressure hydrogen storage tank (6-7) during hydrogen storage. The output end of the third switching valve (7) is connected to the second input end of the regenerative heat exchanger (3). The second output end of the regenerative heat exchanger (3) is connected to the hydrogen-consuming device (9). The input end of the fourth switching valve (8) is connected to the output end of the second high-pressure hydrogen storage tank (6-8) during hydrogen storage. The output end of the fourth switching valve (8) is connected to the third input end of the regenerative heat exchanger (3). The third output end of the regenerative heat exchanger (3) is connected to the hydrogen-consuming device (9).

5. The ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy according to claim 2, wherein, The number of hydrogen compressors and heat exchangers in the cold energy multi-stage utilization module (4) is multiple.

6. A method for ammonia cracking to produce hydrogen and hydrogenation based on multi-stage utilization of cold energy, characterized in that, This method is implemented based on an ammonia cracking hydrogen production and hydrogenation device based on cold energy multi-stage utilization as described in any one of claims 1 to 5. The method includes an ammonia cracking hydrogen production process, a hydrogen storage process, and a hydrogenation process: The ammonia cracking hydrogen production process includes the following steps: The liquid ammonia discharged from the ammonia storage tank (1) is depressurized by a pressure reducing valve (2), releases cold energy to the cold energy storage heat exchanger (3) and stores it, then successively passes through the first low-temperature heat exchanger (4-1), the second low-temperature heat exchanger (4-2) and the third low-temperature heat exchanger (4-3), partially vaporizes using the compression heat of the hydrogen compressor, and then enters the first medium-temperature heat exchanger (5-1), the second medium-temperature heat exchanger (5-2), the third medium-temperature heat exchanger (5-3) to be completely vaporized and preheated, and finally enters the ammonia cracker (5-4) to be cracked into hydrogen and nitrogen, with a small amount of ammonia remaining; the cracked products are cooled by the raw material ammonia in the third medium-temperature heat exchanger (5-3), cooled again by the first low-pressure cooler (5-5) and then enter the first low-pressure hydrogen compressor (5-6) for pressurization, and then successively pass through the second medium-temperature heat exchanger (5-2) and the second low-pressure cooler (5-7) for cooling, enter the second low-pressure hydrogen compressor (5-8) for pressurization again to reach the separation pressure, and after heat exchange with the liquid ammonia in the first medium-temperature heat exchanger (5-1), enter the ammonia removal tower (5-9) to separate ammonia and enter the nitrogen removal tower (5-10) to separate nitrogen, obtaining high-purity hydrogen.

7. The ammonia cracking hydrogen production and hydrogenation method based on multi-stage utilization of cold energy according to claim 6, characterized in that, The hydrogen storage process includes the following steps: The high-purity hydrogen obtained after impurity separation successively passes through the first medium-pressure hydrogen compressor (4-4), the third low-temperature heat exchanger (4-3), the second medium-pressure hydrogen compressor (4-5), the second low-temperature heat exchanger (4-2), the third medium-pressure hydrogen compressor (4-6) and the first low-temperature heat exchanger (4-1) for pressurization and uses the cold energy level of liquid ammonia for inter-stage cooling, enters the diverter (6-1) for diversion, one stream passes through the first switching valve (6-2) and successively passes through the first high-pressure hydrogen compressor (6-4) for compression and the high-pressure cooler (6-6) for cooling and then enters the first high-pressure hydrogen storage tank (6-7) for storage, and the other stream passes through the second switching valve (6-3) and enters the second high-pressure hydrogen storage tank (6-8) for storage after being compressed by the second high-pressure hydrogen compressor (6-5).

8. The ammonia cracking hydrogen production and hydrogenation method based on multi-stage utilization of cold energy according to claim 6, characterized in that, The hydrogenation process includes the following steps: The high-pressure hydrogen discharged from the first high-pressure hydrogen storage tank (6-7) enters the cold energy storage heat exchanger (3) through the third switching valve (7), is cooled by the stored cold energy and then supplied to the hydrogen-consuming equipment (9); the high-pressure hydrogen discharged from the second high-pressure hydrogen storage tank (6-8) enters the cold energy storage heat exchanger (3) through the fourth switching valve (8) and is cooled by the cold energy of liquid ammonia and then supplied to the hydrogen-consuming equipment.

9. The ammonia cracking hydrogen production and hydrogenation method based on multi-stage utilization of cold energy according to claim 6, characterized in that, The components of the cracked products include nitrogen and hydrogen, with a small amount of ammonia remaining. The ammonia removal tower (5-9) is used to remove the remaining ammonia, and the nitrogen removal tower (5-10) is used to purify the nitrogen in the products.

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