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

Abstract

The application relates to an ammonia cracking hydrogen production and hydrogenation device and method based on cold energy multi-stage utilization, which 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 storage type heat exchanger to release and store part of cold energy, then enters a cold energy multi-stage utilization module to release residual cold energy for inter-stage cooling of a medium-pressure hydrogen compressor and a low-pressure hydrogen compressor, finally enters an ammonia cracker to be cracked into nitrogen and hydrogen, and a small amount of ammonia gas is left, high-purity hydrogen gas is obtained through an ammonia removal tower and a nitrogen removal tower; in the hydrogen storage process, the high-purity hydrogen gas is further pressurized and sent into a high-pressure hydrogen storage tank after being pressurized and inter-stage cooled by a medium-pressure hydrogen compressor; in the hydrogenation process, high-pressure hydrogen gas discharged from the high-pressure hydrogen storage tank is cooled by the cold storage type heat exchanger by using the stored liquid ammonia cold energy and then supplied to a hydrogen-consuming device. The application recovers the vaporization cold energy of the liquid ammonia for inter-stage cooling, realizes isothermal compression and reduces the energy consumption of the hydrogen compressor.

Description

Technical Field

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

[0002] Due to the high carbon emissions and other issues associated with traditional fossil fuel hydrogen production, water electrolysis faces cost and efficiency bottlenecks. Most importantly, hydrogen storage and transportation requirements are extremely high. Ammonia cracking hydrogen production technology addresses these challenges by cracking ammonia, a hydrogen-rich carrier. As a mature chemical product, ammonia combines the advantages of high hydrogen density, easy liquefaction, and being carbon-free. It can be decomposed into hydrogen and nitrogen under the action of a catalyst. Furthermore, as a mature chemical product, ammonia has relatively well-developed production, storage, and transportation infrastructure, which can effectively reduce the construction costs of the hydrogen energy industry chain.

[0003] Hydrogen refueling stations, as crucial infrastructure for hydrogen energy applications, face the pain points of high storage and transportation costs and significant safety risks associated with their traditional external hydrogen supply model. Coupling ammonia cracking hydrogen production with a hydrogenation system can achieve integrated hydrogen production, storage, and refueling within the station. However, significant amounts of cold and heat energy remain unutilized during the hydrogen production and refueling process, increasing equipment costs and the difficulty of industrialization. To address this challenge, developing an ammonia cracking hydrogen production and refueling system capable of efficient energy recovery and utilization is key to promoting the commercialization of this technology and improving its economic viability.

[0004] Patent CN116241803A discloses a one-stop, on-site hydrogen production and refueling workstation. By combining wind power and photovoltaics, the station is integrated and miniaturized, utilizing multi-stage heat exchange to fully utilize thermal energy. However, it fails to utilize the cooling energy of liquid ammonia, resulting in a waste of cooling capacity. Patent CN114508699A invents an integrated energy supply system for hydrogen production and refueling through ammonia cracking. By acting as both a hydrogen carrier and an energy carrier, it achieves a comprehensive and efficient supply of multiple energy sources, including hydrogen, electricity, heat, and cooling. However, this system requires additional hydrogen, making it unable to achieve hydrogen self-sufficiency and resulting in a complex system with high maintenance costs.

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

[0006] In response to 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-stage utilization of cold energy, which utilizes liquid ammonia cold energy to exchange heat with high-temperature medium-pressure hydrogen, reduce the inlet temperature of the hydrogen compressor, and achieve isothermal compression. At the same time, low-valley electricity is used to drive the ammonia cracking reaction process, store the liquid ammonia cold energy and hydrogen, and release the cold energy and hydrogen during peak hours, thereby significantly improving the energy utilization efficiency and economy of traditional ammonia cracking hydrogen production and hydrogenation systems.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An ammonia cracking hydrogen production and hydrogenation device based on multi-stage 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 connected to the hydrogen storage unit and the hydrogenation unit respectively;

[0009] The ammonia cracking hydrogen production unit is used to use the compression heat to vaporize and preheat the liquid ammonia step by step, and then crack it into nitrogen and hydrogen, and finally obtain high-purity hydrogen through separation and purification;

[0010] The hydrogen storage unit is used to pressurize high-purity hydrogen step by step, cool it between stages through liquid ammonia cooling energy, and then send it into the high-pressure hydrogen storage tank;

[0011] The hydrogenation unit is used to supply the high-pressure hydrogen in the high-pressure hydrogen storage tank to the hydrogen-using equipment after cooling.

[0012] Preferably, the ammonia cracking hydrogen production unit includes an ammonia storage tank, a pressure reducing valve, a cold storage heat exchanger, a cold energy multi-stage utilization module, and an ammonia cracking hydrogen production module; the cold energy multi-stage 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;

[0013] The output end of the ammonia storage tank is connected to the input end of the pressure reducing valve, the output end of the pressure reducing valve is connected to the first input end of the cold storage heat exchanger, the first output end of the cold storage heat exchanger is connected to the first input end of the first low-temperature heat exchanger in the cold energy multi-stage 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 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 the ammonia cracker, and the output end of the ammonia cracker is connected to the third The second input end of the medium-temperature heat exchanger is connected, 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 the ammonia removal tower, the product output end of the ammonia removal tower is connected to the input end of the nitrogen removal tower, 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 in the hydrogen storage process, and the impurity output end of the nitrogen removal tower is connected to the environment.

[0014] Preferably, the hydrogen storage unit and the ammonia cracking hydrogen production unit share 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, and the hydrogen storage unit further includes a second medium-pressure hydrogen compressor, a third medium-pressure hydrogen compressor and a hydrogen storage module of a cold energy multi-stage 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;

[0015] The input end of the first medium-pressure hydrogen compressor is connected to the denitrification 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, and the second output end of the first low-temperature heat exchanger is connected to the input end of the third medium-pressure hydrogen compressor. The first end 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 switch valve, the output end of the first switch 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 switch valve, the output end of the second switch valve is connected to the input end of the second high-pressure hydrogen compressor, and the output end of the second high-pressure hydrogen compressor is connected to the input end of the second high-pressure hydrogen storage tank.

[0016] Preferably, the hydrogenation unit and the ammonia cracking hydrogen production unit share a cold storage heat exchanger, and the hydrogenation unit further includes a third on-off valve, a fourth on-off valve and a hydrogen use device;

[0017] The input end of the third switch valve is connected to the output end of the first high-pressure hydrogen storage tank during the hydrogen storage process, the output end of the third switch valve is connected to the second input end of the cold storage heat exchanger, the second output end of the cold storage heat exchanger is connected to the hydrogen-using equipment, the input end of the fourth switch valve is connected to the output end of the second high-pressure hydrogen storage tank during the hydrogen storage process, the output end of the fourth switch valve is connected to the third input end of the cold storage heat exchanger, and the third output end of the cold storage heat exchanger is connected to the hydrogen-using equipment.

[0018] Preferably, the number of hydrogen compressors and heat exchangers in the cold energy multi-stage utilization module can be multiple, not limited to three.

[0019] The present invention also provides an ammonia cracking hydrogen production and hydrogenation method based on multi-stage utilization of cold energy. The method is implemented based on the above-mentioned ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy. The method includes an ammonia cracking hydrogen production process, a hydrogen storage process, and a hydrogenation process:

[0020] The ammonia cracking hydrogen production process comprises the following steps:

[0021] The liquid ammonia discharged from the ammonia storage tank is decompressed by a pressure reducing valve, releasing cold energy to the cold storage heat exchanger for storage, and then passes through the first low-temperature heat exchanger, the second low-temperature heat exchanger and the third low-temperature heat exchanger in sequence, and is partially vaporized by 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 for complete vaporization and preheating, and finally enters the ammonia cracker for cracking into hydrogen and nitrogen, with a small amount of ammonia remaining; the cracking product is cooled by the raw ammonia through the third medium-temperature heat exchanger, cooled again through the first low-pressure cooler, and then enters the first low-pressure hydrogen compressor for pressurization, and then passes through the second medium-temperature heat exchanger and the second low-pressure cooler in sequence for cooling, and enters the second low-pressure hydrogen compressor for pressurization again to reach the separation pressure. After heat exchange with 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 to obtain high-purity hydrogen.

[0022] Preferably, the hydrogen storage process comprises the following steps:

[0023] The high-purity hydrogen obtained after impurity separation is pressurized in turn 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 and cooled between stages using liquid ammonia cooling energy. It enters the splitter for diversion. One stream passes through the first switch valve and is compressed by the first high-pressure hydrogen compressor and cooled by the high-pressure cooler before entering the first high-pressure hydrogen storage tank for storage. The other stream passes through the second switch valve and is compressed by the second high-pressure hydrogen compressor before entering the second high-pressure hydrogen storage tank for storage.

[0024] Preferably, the hydrogenation process comprises the following steps:

[0025] The high-pressure hydrogen discharged from the first high-pressure hydrogen storage tank enters the cold storage heat exchanger through the third switch valve, and is supplied to the hydrogen-using equipment after being cooled by the stored cold energy; the high-pressure hydrogen discharged from the second high-pressure hydrogen storage tank enters the cold storage heat exchanger through the fourth switch valve, and is supplied to the hydrogen-using equipment after being cooled by the liquid ammonia cold energy.

[0026] Preferably, the cracking product components mainly include nitrogen and hydrogen, with a small amount of residual ammonia. The ammonia removal tower is mainly used to remove the residual ammonia, and the nitrogen removal tower is mainly used to purify nitrogen in the product.

[0027] The present invention adopts the above technical solution, which has the following beneficial effects:

[0028] 1. The present invention configures a multi-stage hydrogen compressor and a corresponding heat exchanger, utilizes the vaporization cold energy of the raw material liquid ammonia to cool the compressed high-temperature hydrogen, realizes isothermal compression, and thus reduces the energy consumption of the hydrogen compressor.

[0029] 2. The present invention uses low-peak electricity at night to drive the ammonia cracking reaction, stores the cold energy of liquid ammonia in a cold storage heat exchanger, and stores high-pressure hydrogen in a high-pressure hydrogen storage tank, which is released when hydrogen is used during peak hours. At the same time, the cold energy stored in the cold storage heat exchanger is used to cool the hydrogen, thereby improving hydrogenation efficiency and reducing safety risks.

[0030] 3. The present invention couples the ammonia cracking hydrogen production system with the hydrogen refueling station to improve system integration, reduce floor space, and reduce energy loss and system operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of an ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy in an embodiment of the present invention.

[0032] Reference numerals:

[0033] 1- ammonia storage tank, 2- pressure reducing valve, 3- cold storage heat exchanger, 4- cold energy multi-stage 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 cold 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 switch valve, 6-3 second switch 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 switch valve, 8-fourth switch valve, 9-hydrogen equipment. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0035] 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 form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] In order to improve the efficiency of hydrogen production from ammonia, rationally utilize the cooling capacity of the raw ammonia gas and utilize the waste heat of compression, the present invention provides an ammonia cracking hydrogen production and hydrogenation device and method based on multi-stage utilization of cold energy, coupling ammonia cracking hydrogen production with hydrogen storage and hydrogenation to enhance the cracking reaction and fully utilize the cooling capacity of the raw ammonia gas and the waste heat of compression, which includes an ammonia cracking hydrogen production unit, a hydrogen storage unit and a hydrogenation unit. During the off-peak period at night, the liquid ammonia discharged from the ammonia storage tank 1 is reduced in pressure by the pressure reducing valve 2, and releases cold energy to the cold storage heat exchanger 3 for storage. Then, it 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 in sequence. 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. Finally, it enters the ammonia cracker 5-4 to be cracked into hydrogen and nitrogen, with a small amount of ammonia remaining. The cracking product is cooled by the raw ammonia through the third medium-temperature heat exchanger 5-3, cooled again through the first low-pressure cooler 5-5, and then enters the first low-pressure hydrogen compressor 5-6 for pressurization, and then 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 re-pressurization to reach the separation pressure, passes through the first medium-temperature heat exchanger 5-1 for heat exchange with liquid ammonia, enters the ammonia removal tower 5-9 for separation of ammonia, and enters the nitrogen removal tower 5-10 for separation of nitrogen; the high-purity hydrogen obtained after impurity separation 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 in sequence, is pressurized multiple times and the liquid ammonia cold energy is used to cool the compression heat energy. The cooled high-pressure hydrogen enters the splitter 6-1 for diversion, and is compressed and cooled or compressed and stored in the first high-pressure hydrogen storage tank 6-7 and the second high-pressure hydrogen storage tank 6-8 respectively. When the hydrogen terminal needs hydrogen during the daytime peak period, the high-pressure hydrogen discharged from the first high-pressure hydrogen storage tank 6-7 passes through the third switch valve 7 to the cold storage heat exchanger 3, and is cooled by the cold energy stored at night and supplied to the hydrogen equipment 9. The high-pressure hydrogen discharged from the second high-pressure hydrogen storage tank 6-8 passes through the fourth switch valve 8 to the cold storage heat exchanger 3, and is cooled by the liquid ammonia cold energy and supplied to the hydrogen equipment.

[0037] In one embodiment of the present invention, a hydrogenation device for producing hydrogen by cracking ammonia based on multi-stage utilization of cold energy is provided. In this embodiment, Figure 1 As shown, the thick solid line represents the raw ammonia pipeline, the thin solid line represents the hydrogen pipeline, and the short horizontal line represents the ammonia cracking product pipeline. The system includes an ammonia cracking hydrogen production process, a hydrogen storage process, and a hydrogenation process, wherein:

[0038] In an optional embodiment, the ammonia cracking unit includes: an ammonia storage tank 1, a pressure reducing valve 2, a cold storage 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.

[0039] 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 storage heat exchanger 3, the first output end of the cold 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, and the third low-temperature heat exchanger 4-4 is connected to the first low-temperature heat exchanger 4-5. The first output end of the 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 first input end of the third medium-temperature heat exchanger 5-3. The second input 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, and the output end of the second low-pressure cooler 5-7 is connected to the second low-pressure hydrogen compressor 5-8. The input 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 in the hydrogen storage process, and the impurity output end of the nitrogen removal tower 5-10 is connected to the environment.

[0040] In an optional embodiment, 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 and the third low-temperature heat exchanger 4-3. In addition, the hydrogen storage unit also 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 switch valve 6-2, a second switch 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;

[0041] The input end of the first medium-pressure hydrogen compressor 4-4 is connected to the denitrification 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, and the second output end of the first low-temperature heat exchanger 4-1 is connected to the hydrogen storage module. The input end of the diverter 6-1 in block 6 is connected, the first output end of the diverter 6-1 is connected to the input end of the first switch valve 6-2, the output end of the first switch 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 switch valve 6-3, the output end of the second switch valve 6-3 is connected to the input end of the second high-pressure hydrogen compressor 6-5, and 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.

[0042] In an optional embodiment, the hydrogenation unit and the ammonia cracking hydrogen production unit share the cold storage heat exchanger 3. In addition, the hydrogenation unit further includes a third switch valve 7, a fourth switch valve 8 and a hydrogen use device 9;

[0043] The input end of the third switch valve 7 is connected to the output end of the first high-pressure hydrogen storage tank 6-7, the output end of the third switch valve 7 is connected to the second input end of the cold storage heat exchanger 3, the second output end of the cold storage heat exchanger 3 is connected to the hydrogen-using equipment 9, the input end of the fourth switch valve 8 is connected to the output end of the second high-pressure hydrogen storage tank 6-8, the output end of the fourth switch valve 8 is connected to the third input end of the cold storage heat exchanger 3, and the third output end of the cold storage heat exchanger 3 is connected to the hydrogen-using equipment 9.

[0044] In one embodiment of the present invention, a method for producing hydrogen from ammonia by 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 and hydrogenation apparatus based on multi-stage utilization of cold energy in the above embodiments. The hydrogenation station method includes the following steps:

[0045] 1) Liquid ammonia discharged from the ammonia storage tank 1 is depressurized by the pressure reducing valve 2, releasing cold energy to the cold storage heat exchanger 3 for storage. The ammonia then 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 in sequence. The ammonia is partially vaporized by the heat of compression of the hydrogen compressor. The ammonia 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 for complete vaporization and preheating. Finally, the ammonia enters the ammonia cracker 5-4 for cracking into hydrogen and nitrogen, with a small amount of residual ammonia. The cracking product is cooled by the raw ammonia through the third medium-temperature heat exchanger 5-3, cooled again through the first low-pressure cooler 5-5, and then enters the first low-pressure hydrogen compressor 5-6 for pressurization. Then, it is cooled in turn through the second medium-temperature heat exchanger 5-2 and the second low-pressure cooler 5-7, and enters the second low-pressure hydrogen compressor 5-8 for pressurization again to reach the separation pressure. After heat exchange with liquid ammonia through the first medium-temperature heat exchanger 5-1, it enters the ammonia removal tower 5-9 to separate ammonia, and enters the nitrogen removal tower 5-10 to separate nitrogen, thereby obtaining high-purity hydrogen.

[0046] 2) The high-purity hydrogen obtained after impurity separation 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 in sequence, is pressurized multiple times and the compression heat energy is cooled by the cold energy of liquid ammonia. The cooled high-pressure hydrogen enters the splitter 6-1 for splitting. One stream passes through the first switch valve 6-2, is compressed by the first high-pressure hydrogen compressor 6-4, and is cooled by the high-pressure cooler 6-6 before entering the first high-pressure hydrogen storage tank 6-7 for storage. The other stream passes through the second switch 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.

[0047] 3) The high-pressure hydrogen discharged from the first high-pressure hydrogen storage tank 6-7 passes through the third switch valve 7 to the cold storage heat exchanger 3, is cooled by the stored cold energy, and is supplied to the hydrogen-using equipment 9. The high-pressure hydrogen discharged from the second high-pressure hydrogen storage tank 6-8 passes through the fourth switch valve 8 to the cold storage heat exchanger 3, is cooled by the liquid ammonia cold energy, and is supplied to the hydrogen-using equipment.

[0048] The method provided in this embodiment is based on the above-mentioned system embodiments. Please refer to the above-mentioned embodiments for specific processes and detailed contents, which will not be repeated here.

[0049] In summary, this invention utilizes the cold energy from the vaporization of recovered liquid ammonia for interstage cooling, achieving isothermal compression and reducing hydrogen compressor energy consumption. Furthermore, nighttime off-peak electricity can be used to drive the ammonia cracking and hydrogen storage processes, storing the hydrogen and cold energy for release during peak hours. This reduces system operating costs, improves hydrogenation efficiency, and mitigates safety risks.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy, characterized in that: include: An ammonia cracking hydrogen production unit, a hydrogen storage unit and a hydrogenation unit; the ammonia cracking hydrogen production unit is connected to the hydrogen storage unit and the hydrogenation unit respectively; The ammonia cracking hydrogen production unit is used to use the compression heat to vaporize and preheat the liquid ammonia step by step, and 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, cool it between stages through liquid ammonia cooling energy, and then send it into the 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-using equipment after cooling; The ammonia cracking hydrogen production unit comprises an ammonia storage tank (1), a pressure reducing valve (2), a cold storage heat exchanger (3), a cold energy multi-stage utilization module (4), and an ammonia cracking hydrogen production module (5); the cold energy multi-stage utilization module (4) comprises 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 ammonia cracking hydrogen production module (5) comprises 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 storage heat exchanger (3), the first output end of the cold 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), and the third low-temperature heat exchanger (4-3) is connected to the first input end of the first low-temperature heat exchanger (4-1). The first output end of the medium-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 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 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) in the hydrogen storage process, and the impurity output end of the nitrogen removal tower (5-10) is connected to the environment; The nighttime off-peak electricity is used to drive the ammonia cracking reaction, and the cold energy of liquid ammonia is stored in a cold storage heat exchanger. High-pressure hydrogen is stored in a high-pressure hydrogen storage tank and released when hydrogen is needed during peak hours. At the same time, the cold energy stored in the cold storage heat exchanger is used to cool the hydrogen.

2. The ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy according to claim 1, characterized in that: The hydrogen storage unit and the ammonia cracking hydrogen production unit share 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 storage unit also includes a second medium-pressure hydrogen compressor (4-5), a third medium-pressure hydrogen compressor (4-6) and a hydrogen storage module (6) of the cold energy multi-stage utilization module (4); the hydrogen storage module (6) includes a diverter (6-1), a first switch valve (6-2), a second switch 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 denitrification 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), and the second output end of the first low-temperature heat exchanger (4-1) is connected to the hydrogen storage module. (6) is connected to the input end of the diverter (6-1), the first output end of the diverter (6-1) is connected to the input end of the first switch valve (6-2), the output end of the first switch 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 switch valve (6-3), the output end of the second switch valve (6-3) is connected to the input end of the second high-pressure hydrogen compressor (6-5), and 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).

3. The ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy according to claim 1, characterized in that: The hydrogenation unit and the ammonia cracking hydrogen production unit share a cold storage heat exchanger (3), and the hydrogenation unit further includes a third switch valve (7), a fourth switch valve (8) and a hydrogen use device (9); The input end of the third switch valve (7) is connected to the output end of the first high-pressure hydrogen storage tank (6-7) during the hydrogen storage process, the output end of the third switch valve (7) is connected to the second input end of the cold storage heat exchanger (3), the second output end of the cold storage heat exchanger (3) is connected to the hydrogen-using device (9), the input end of the fourth switch valve (8) is connected to the output end of the second high-pressure hydrogen storage tank (6-8) during the hydrogen storage process, the output end of the fourth switch valve (8) is connected to the third input end of the cold storage heat exchanger (3), and the third output end of the cold storage heat exchanger (3) is connected to the hydrogen-using device (9).

4. The ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy according to claim 1, characterized in that: The number of hydrogen compressors and heat exchangers in the cold energy multi-stage utilization module (4) is multiple.

5. A method for producing hydrogen by cracking ammonia based on multi-stage utilization of cold energy, characterized in that: The method is implemented based on an ammonia cracking hydrogen production and hydrogenation device based on multi-stage utilization of cold energy as described in any one of claims 1 to 4, and the method includes an ammonia cracking hydrogen production process, a hydrogen storage process and a hydrogenation process: The ammonia cracking hydrogen production process comprises the following steps: The liquid ammonia discharged from the ammonia storage tank (1) is decompressed by the pressure reducing valve (2), and releases cold energy to the cold storage heat exchanger (3) for storage. The liquid ammonia then 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) in sequence, and is partially vaporized by the compression heat of the hydrogen compressor. The liquid ammonia 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. The liquid ammonia finally enters the ammonia cracker (5-4) to be cracked into hydrogen and nitrogen, with a small amount of ammonia remaining. The product is cooled by the raw ammonia through the third medium-temperature heat exchanger (5-3), cooled again through the first low-pressure cooler (5-5), and then enters the first low-pressure hydrogen compressor (5-6) for pressurization. It is then cooled in turn through the second medium-temperature heat exchanger (5-2) and the second low-pressure cooler (5-7), and enters the second low-pressure hydrogen compressor (5-8) for pressurization again to reach the separation pressure. After heat exchange with liquid ammonia through the first medium-temperature heat exchanger (5-1), it enters the ammonia removal tower (5-9) to separate ammonia and enters the nitrogen removal tower (5-10) to separate nitrogen to obtain high-purity hydrogen.

6. The method for producing hydrogen from ammonia by cracking and hydrogenation based on multi-stage utilization of cold energy according to claim 5, characterized in that: The hydrogen storage process comprises the following steps: The high-purity hydrogen obtained after impurity separation is pressurized 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) and cooled between stages using liquid ammonia cooling energy, and then enters the splitter (6-1) for splitting. One stream passes through the first switch valve (6-2) and 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 switch valve (6-3) and 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.

7. The method for producing hydrogen from ammonia by cracking and hydrogenation based on multi-stage utilization of cold energy according to claim 5, characterized in that: The hydrogenation process comprises the following steps: The high-pressure hydrogen gas discharged from the first high-pressure hydrogen storage tank (6-7) enters the cold storage heat exchanger (3) through the third switch valve (7), is cooled by the stored cold energy, and is then supplied to the hydrogen-using equipment (9); the high-pressure hydrogen gas discharged from the second high-pressure hydrogen storage tank (6-8) enters the cold storage heat exchanger (3) through the fourth switch valve (8), is cooled by the liquid ammonia cold energy, and is then supplied to the hydrogen-using equipment.

8. The method for producing hydrogen from ammonia by cracking and hydrogenation based on multi-stage utilization of cold energy according to claim 5, characterized in that: The cracking product components include nitrogen and hydrogen, and a small amount of ammonia remains. The ammonia removal tower (5-9) is used to remove the residual ammonia, and the nitrogen removal tower (5-10) is used to purify the nitrogen in the product.

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