Micro-tube type ammonia hydrogen conversion system

Abstract

The present application relates to the field of new energy and hydrogen energy technology, and more particularly to a micro-tube type ammonia-hydrogen conversion system, which forms a micro-tube array integrated ammonia decomposition device by arranging a plurality of micro-pipes inside a reaction cavity, utilizes partial hydrogen generated by ammonia decomposition to provide heat through catalytic oxidation inside the micro-pipe catalytic reactor, simultaneously in-situ heats the ammonia catalytic decomposition reaction outside the micro-pipe catalytic reactor, synchronously couples the catalytic oxidation heat release and the catalytic decomposition heat absorption together through system integration and structure design, fully utilizes the self heat of the reaction, and does not need external heating, thereby greatly improving the energy utilization efficiency, and has no harmful pollutant emission and no carbon emission; and the micro-tube type ammonia-hydrogen conversion system has the advantages of small volume and high safety, and provides a feasible scheme for the application of mobile occasions and high space utilization rate scenarios of zero-carbon hydrogen energy power.

Description

Technical Field

[0001] This invention relates to the fields of new energy and hydrogen energy technology, and in particular to a microtubular ammonia-hydrogen conversion system. Background Technology

[0002] As human society develops, the demand for energy is increasing. However, the use of traditional fossil fuels is causing greenhouse gas emissions that have a deepening impact on the environment. Therefore, it is necessary to develop and utilize clean energy to break free from dependence on fossil fuels.

[0003] Hydrogen energy has received widespread attention as a clean energy source. Hydrogen gas boasts advantages such as high energy density and zero carbon emissions, making it considered one of the most promising secondary energy sources. However, hydrogen gas presents significant challenges in storage and transportation due to its flammability, explosiveness, difficulty in compression, and reactive chemical properties. Ammonia, as a carbon-free hydrogen carrier, decomposes into hydrogen and pollution-free nitrogen, making it a highly promising hydrogen carrier. However, the decomposition of ammonia requires a catalyst and is carried out under heating conditions. Traditional ammonia decomposition reactors mainly consist of an inlet system, an ammonia decomposition reaction chamber, a gas separation system, a tail gas treatment system, and a heat exchange system.

[0004] However, traditional ammonia decomposition devices are too large and complex to be used in mobile and space-constrained applications such as ships, trucks, buses, and drones. Since ammonia decomposition requires heat, they are categorized as self-heating or non-self-heating based on whether an external heat source is needed. Non-self-heating ammonia decomposition devices typically require fuel combustion or external power to maintain the required reaction temperature. For devices with external power supply heating (publication numbers: CN217910438U, CN218202205U), a high-power external power supply is required, limiting their use in mobile applications such as trucks and drones. Typical combustion heaters use fuels such as methane and butane, which emit large amounts of carbon oxides after combustion (publication numbers: CN203625025U, CN211521580U). External burners occupy additional space and result in significant heat exchange losses, leading to reduced overall efficiency and increased energy consumption. Self-heating ammonia decomposition devices typically use hydrogen from the ammonia feedstock or decomposition products for direct combustion heating. Ammonia is difficult to ignite, and its combustion or oxidation products are nitrogen oxides (NOx). x It is a major inducing substance for photochemical smog, haze, and acid rain, and belongs to the category of harmful air pollutants whose emissions are strictly controlled. For devices that use hydrogen produced by decomposition for combustion heating, the existing invention (publication number: CN112050202A) uses a separate fixed-bed reactor as the hydrogen burner. The fuel heat zone is far away from the ammonia decomposition reaction zone, which makes it impossible to fully and effectively utilize the heat of hydrogen combustion. Moreover, due to the flammable and explosive nature of hydrogen, the operational safety performance cannot be guaranteed.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a microtube ammonia-hydrogen conversion system, which aims to solve the problems of excessive size, insufficient efficiency, limited mobility, and lack of safety of traditional ammonia decomposition devices.

[0007] The technical solution of the present invention is as follows: A microtubular ammonia-hydrogen conversion system includes a heat exchange device and a reaction device; The heat exchange device includes a cold medium pipe and a hot medium pipe arranged at intervals; one end of the cold medium pipe is provided with an ammonia raw material inlet and the other end is provided with a cold medium pipe outlet; one end of the hot medium pipe is provided with a hot medium pipe inlet and the other end is provided with a first decomposition gas outlet and a second decomposition gas outlet. The reaction device includes a reaction chamber, a premixed gas chamber, and a tail gas collection chamber. The reaction chamber has several microchannels inside. One end of each microchannel communicates with the premixed gas chamber, and the other end communicates with the tail gas collection chamber. The outlet of the cold medium pipe communicates with the reaction chamber. The outlet of the second decomposed gas communicates with the premixed gas chamber. The inlet of the hot medium pipe communicates with the reaction chamber. The inner surface of each microchannel is provided with a hydroxide catalyst layer, and the outer surface of each microchannel is provided with an ammonia decomposition catalyst layer.

[0008] In the aforementioned microtubular ammonia-hydrogen conversion system, the cold medium tube and the hot medium tube are arranged in parallel to each other; both the cold medium tube and the hot medium tube have an S-shaped structure.

[0009] The microtubular ammonia-hydrogen conversion system further includes a heat-insulating base; the heat-insulating base, the heat exchange device, and the reaction device are stacked sequentially to form a layer structure.

[0010] The microtube ammonia-hydrogen conversion system further includes a shell, in which the cold medium pipe and the hot medium pipe are disposed; a start-up preheater is attached to the inner wall of the shell.

[0011] The microtube-type ammonia-hydrogen conversion system wherein the microtube is selected from one of the following: straight circular tube, straight flat tube, serpentine flat tube, coiled circular tube, and coiled flat tube.

[0012] The microtubular ammonia-hydrogen conversion system is provided with a heat-insulating sleeve attached to the inner wall of the reaction chamber.

[0013] In the aforementioned microtubular ammonia-hydrogen conversion system, the reaction chamber is provided with a reaction chamber outlet, and the reaction chamber outlet is connected to the heat medium pipe inlet via a first pipe.

[0014] In the aforementioned microtubular ammonia-hydrogen conversion system, the gas outlet of the reaction chamber is located diagonally opposite the gas outlet of the cold medium pipe.

[0015] In the aforementioned microtubular ammonia-hydrogen conversion system, the second decomposed gas outlet is connected to the premixed gas chamber via a second pipe; the second pipe is equipped with a first one-way valve and a first flow meter; the second pipe is also equipped with an air inlet pipe connection port, the air inlet pipe connection port being connected to an air inlet pipe, and the air inlet pipe being equipped with a second one-way valve and a second flow meter.

[0016] The microtubular ammonia-hydrogen conversion system wherein the inner diameter of the microtubule is less than or equal to 2.5 mm and the wall thickness of the microtubule is 0.1-2 mm.

[0017] Beneficial Effects: This invention provides a microtube-type ammonia-hydrogen conversion system. By incorporating several microchannels within the reaction chamber to form an integrated ammonia decomposition device, a portion of the hydrogen generated from ammonia decomposition is used for catalytic oxidation within the microtube catalytic reactor to provide heat. Simultaneously, the ammonia catalytic decomposition reaction is heated in situ outside the microtube catalytic reactor. Through system integration and structural design, the exothermic catalytic oxidation and endothermic catalytic decomposition are coupled synchronously, fully utilizing the reaction's own heat without external heating, thus significantly improving energy efficiency. Furthermore, there are no harmful pollutant emissions or carbon emissions. This microtube-type ammonia-hydrogen conversion system also boasts advantages such as small size and high safety, providing a feasible solution for applications in zero-carbon hydrogen-powered mobile applications and high-space-utilization scenarios. Moreover, by incorporating a hydroxide catalyst layer on the inner surface of the microchannels, this invention allows the microtube-type ammonia-hydrogen conversion system to start at 100°C without an open flame. Compared to existing methods that require hydrogen combustion at temperatures above 600°C and produce an open flame, this microtube-type ammonia-hydrogen conversion system offers advantages in low-temperature start-up and safety. Furthermore, this invention employs a core-shell microtube array to couple the catalytic oxidation of hydrogen in the decomposition gas with the catalytic decomposition of ammonia, combining the exothermic reaction of the former with the endothermic reaction of the latter in situ, thereby improving energy and space utilization efficiency and effectively meeting the needs of mobile and volume-sensitive applications powered by zero-carbon hydrogen energy. Moreover, the use of several microtubes to form a microtube array structure makes fabrication and preparation simple, facilitates large-scale production, allows for flexible combination, easily adjusts capacity, solves the airtightness problem, facilitates disassembly, and improves the safety of hydrogen use. Attached Figure Description

[0018] Figure 1This is a three-dimensional structural schematic diagram of a microtubular ammonia-hydrogen conversion system according to the present invention; Figure 2 This is a left cross-sectional view of a microtubular ammonia-hydrogen conversion system according to the present invention; Figure 3 This is a bottom view of the heat exchange device described in this invention; Figure 4 This is a cross-sectional view of the microchannel described in this invention; Explanation of reference numerals in the attached drawings: heat exchange device 10, cold medium pipe 11, ammonia feed inlet 111, cold medium pipe outlet 112, hot medium pipe 12, hot medium pipe inlet 121, first decomposition gas outlet 122, second decomposition gas outlet 123, reaction device 20, reaction chamber 21, microchannel 211, hydroxide catalyst layer 212, ammonia decomposition catalyst layer 213, reaction chamber outlet 214, premixed gas chamber 22, tail gas collection chamber 23, combustion tail gas outlet 231, heat insulation base 30, start-up preheater 40, heat insulation jacket 50, first pipe 60, second pipe 70, first one-way valve 71, first flow meter 72, air inlet pipe 80, second one-way valve 81, second flow meter 82, premixed gas chamber inlet 90. Detailed Implementation

[0019] This invention provides a microtubular ammonia-hydrogen conversion system. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0021] Traditional separate ammonia decomposition units (publication numbers: CN217230245U, CN115092884A) are too large and complex in composition to be used in hydrogen-powered mobile applications or in space-constrained situations. In integrated ammonia decomposition units, for self-heating ammonia decomposition equipment, the fuel typically used is either the raw material ammonia or hydrogen from the decomposition products. For devices that utilize ammonia combustion for heating (reference: Chiuta S, Bessarabov DG. Design and operation of an ammonia-fueled microchannel reactor for autothermal hydrogen production[J]. Catalysis Today, 2017:S0920586117303279), ammonia (NH3) is difficult to ignite, leading to ignition difficulties, incomplete combustion, and combustion products containing large amounts of atmospheric pollutant NO. x Residual fuel leads to secondary pollution from NH3 emissions.

[0022] In addition, in existing ammonia decomposition devices that use hydrogen combustion of decomposition products for self-heating, the hydrogen combustion reactor is a separate fixed-bed reactor (publication number: CN217230245U, CN115092884A). This traditional separate system structure makes the hydrogen combustion exothermic zone far away from the ammonia decomposition reaction zone. It is necessary to use a heat exchange system to transfer the waste heat of the fuel exhaust gas to the reaction zone, resulting in low energy efficiency and a complex system.

[0023] Based on this, such as Figures 1-4 As shown, the present invention provides a microtubular ammonia-hydrogen conversion system, including a heat exchange device 10 and a reaction device 20; The heat exchange device 10 includes a cold medium pipe 11 and a hot medium pipe 12 arranged at intervals; one end of the cold medium pipe 11 is provided with an ammonia raw material inlet 111 and the other end is provided with a cold medium pipe outlet 112; one end of the hot medium pipe 12 is provided with a hot medium pipe inlet 121 and the other end is provided with a first decomposition gas outlet 122 and a second decomposition gas outlet 123. The reaction device 20 includes a reaction chamber 21, a premixed gas chamber 22, and a tail gas collection chamber 23. The reaction chamber 21 is provided with a plurality of microchannels 211. One end of each microchannel 211 is connected to the premixed gas chamber 22, and the other end is connected to the tail gas collection chamber 23. The outlet 112 of the cold medium pipe is connected to the reaction chamber 21. The second decomposition gas outlet 123 is connected to the premixed gas chamber 22. The inlet 121 of the hot medium pipe is connected to the reaction chamber 21. The inner surface of the microchannel 211 is provided with a hydroxide catalyst layer 212, and the outer surface of the microchannel 211 is provided with an ammonia decomposition catalyst layer 213.

[0024] In this embodiment, the heat exchange device, ammonia decomposition reactor, and heating device in the ammonia-hydrogen conversion system are integrated and coupled into one unit. This not only results in a compact structure and improved space utilization but also effectively enhances thermal efficiency, providing a practical microtube-type ammonia-hydrogen conversion system for mobile applications and scenarios with high space utilization requirements. Furthermore, the microtube-type ammonia-hydrogen conversion system utilizes the exothermic catalytic oxidation of hydrogen in the decomposition gas to provide the heat required for ammonia decomposition. Only a small portion of the decomposition gas needs to be recovered to achieve self-heating, fully leveraging the advantages of hydrogen's high calorific value and the fact that the reaction product is water, which is pollution-free and carbon-free, thus achieving self-heating, zero emissions, and zero pollution.

[0025] Specifically, by providing a hydroxide catalyst layer 212 on the inner surface of the microchannel 211, the microtube-type ammonia-hydrogen conversion system can be started at 100°C without an open flame. Compared to existing systems that require hydrogen combustion at temperatures above 600°C and produce an open flame, this microtube-type ammonia-hydrogen conversion system offers advantages in low-temperature start-up and safety. Furthermore, this embodiment employs a core-shell microtube array, coupling the catalytic oxidation of hydrogen in the decomposition gas with the catalytic decomposition of ammonia. This combines the exothermic reaction of the former with the endothermic reaction of the latter in situ, improving energy and space utilization, effectively meeting the needs of mobile and volume-sensitive applications powered by zero-carbon hydrogen energy. Moreover, the use of several microchannels 211 to form a microtube array structure simplifies fabrication, facilitates large-scale production, allows for flexible combination and easy capacity adjustment, solves the airtightness problem, facilitates disassembly, and improves the safety of hydrogen use.

[0026] In some implementations, such as Figure 3 As shown, the cold medium pipe 11 and the hot medium pipe 12 are arranged in parallel to each other; both the cold medium pipe 11 and the hot medium pipe 12 have an S-shaped structure. The parallel arrangement of the cold medium pipe 11 and the hot medium pipe 12 facilitates heat exchange between the high-temperature gas after decomposition and the introduced ammonia gas; and the S-shaped structure of the cold and hot medium pipes allows for longer cold and hot medium pipes within a limited space, improving heat exchange efficiency.

[0027] Specifically, the heat exchange device 10 includes two parallel serpentine tubes, one being a cold medium tube and the other a hot medium tube. Ammonia gas introduced into the cold medium tube 11 through the ammonia raw material inlet 111 exchanges heat with the high-temperature gas after decomposition introduced into the hot medium tube 12 through the hot medium tube inlet 121, thereby achieving high-efficiency heat exchange in a relatively small space.

[0028] In some embodiments, the microtubular ammonia-hydrogen conversion system further includes a heat-insulating base 30; the heat-insulating base 30, the heat exchange device 10, and the reaction device 20 are stacked sequentially to form a layered structure. By utilizing this layered structure to stack the heat-insulating base 30, the heat exchange device 10, and the reaction device 20, the microtubular ammonia-hydrogen conversion system becomes more compact, improving space utilization and effectively increasing thermal efficiency, providing a practical product for mobile applications and scenarios requiring high space utilization.

[0029] In some embodiments, the heat exchange device 10 further includes a housing, in which the cold medium pipe 11 and the hot medium pipe 12 are disposed; using the housing to house the cold medium pipe 11 and the hot medium pipe 12 inside the housing facilitates the assembly and practical application of the microtubular ammonia-hydrogen conversion system.

[0030] In some embodiments, a start-up preheater 40 is attached to the inner wall of the housing; the start-up preheater 40 is used to provide heat for the microtubular ammonia-hydrogen conversion system during startup.

[0031] Specifically, the start-up preheater 40 is an electric heating jacket that completely wraps around the cold medium pipe 11 and the hot medium pipe 12, which can provide heat when the device is started.

[0032] In some embodiments, the inner wall of the reaction chamber is fitted with a heat insulation sleeve 50; the heat insulation sleeve 50 is composed of heat insulation material, which reduces the heat exchange between the reaction chamber 21 and the outside world, thus preventing heat loss.

[0033] In some embodiments, the reaction chamber 21 is provided with a reaction chamber outlet 214, which is connected to the heat medium pipe inlet 121 via a first pipe 60.

[0034] In some embodiments, the reaction chamber outlet 214 is located diagonally opposite the cold medium pipe outlet 112.

[0035] Specifically, the gas outlet 214 of the reaction chamber and the gas outlet 112 of the cold medium pipe are arranged diagonally opposite each other, which allows the gas to react fully in the reaction chamber 21. Then, the gas outlet 214 of the reaction chamber extends along the outside of the reaction chamber 21 through the first pipe 60 to the bottom and connects to the gas inlet 121 of the heat medium pipe of the heat exchange device 10. The high-temperature gas after decomposition can be introduced into the heat medium pipe to exchange heat with the ammonia raw material in the cold medium pipe. At the same time, it is collected or utilized at the first decomposition gas outlet 122 and the second decomposition gas outlet 123.

[0036] In some embodiments, the second decomposed gas outlet 123 is connected to the premixed gas chamber 22 via a second pipe 70; the second pipe 70 is provided with a first one-way valve 71 and a first flow meter 72; the second pipe 70 is also provided with an air inlet pipe connection port, the air inlet pipe connection port is connected to an air inlet pipe 80, the air inlet pipe is provided with a second one-way valve 81 and a second flow meter 82.

[0037] Specifically, the second pipe 70 and the air inlet pipe 80 converge to form a premixed gas chamber inlet 90; the second decomposition gas outlet 123 delivers a portion of the decomposition gas through the second pipe 70 to the premixed gas chamber inlet 90, while the air inlet pipe delivers air to the premixed gas chamber inlet 90, so that the mixed gas obtained after premixing is delivered to the premixed gas chamber 22, and then the mixed gas undergoes a catalytic combustion reaction in the hydroxide catalyst layer of the micro-pipe 211, providing heat for ammonia decomposition in the reaction chamber.

[0038] Furthermore, the reaction chamber 21 is provided with 8*6 microchannels inside, each microchannel having an inner diameter of no more than 2.5mm and a wall thickness of 0.1-2mm. One end of each microchannel is connected to the premixed gas chamber 22, and the other end is connected to the exhaust gas collection chamber 23. The exhaust gas collection chamber 23 is provided with a combustion exhaust gas outlet 231 for discharging combustion exhaust gas.

[0039] In some embodiments, the inner diameter of the microchannel is less than or equal to 2.5 mm, and the wall thickness of the microchannel is 0.1-2 mm.

[0040] In some embodiments, the hydroxide catalyst in the hydroxide catalyst layer may be selected from, but is not limited to, one or more of MgAl2O4, Mn-Co-Cu-Fe-Ni / γ-Al2O3 / cordierite, Pt / γ-Al2O3 / cordierite, and Pt / γ-Al2O3.

[0041] In some embodiments, the ammonia decomposition catalyst in the ammonia decomposition catalyst layer may be selected from, but is not limited to, one or more of Fe-based ammonia decomposition catalysts, Ni-based ammonia decomposition catalysts, and Ru-based ammonia decomposition catalysts.

[0042] In some embodiments, the microchannels are selected from, but are not limited to, straight circular tubes, straight flat tubes, serpentine flat tubes, coiled circular tubes, and coiled flat tubes.

[0043] Furthermore, the microtube array composed of the microchannels can be selected from, but is not limited to, one of the following: straight circular tube, straight flat tube, serpentine flat tube, coiled circular tube, and coiled flat tube.

[0044] In some embodiments, the reaction chamber may be in the shape of a cube, cuboid, or cylinder.

[0045] To better illustrate the working principle of the microtubular ammonia-hydrogen conversion system, the following describes its workflow: First, the preheater 40 is turned on to preheat the heat exchange device to the reaction temperature. Then, ammonia gas is introduced into the ammonia feedstock inlet 111. The ammonia gas enters the reaction chamber 21 through the cold medium pipe 11 and comes into contact with the ammonia decomposition catalyst layer on the outer surface of the microchannel 211, where an ammonia decomposition reaction occurs. The decomposed gas after the reaction passes through the reaction chamber outlet 214 and the first pipe 60 to the hot medium pipe 12. After the decomposed gas in the hot medium pipe 12 exchanges heat with the ammonia gas in the cold medium pipe 11 and is cooled, a portion of it passes through the first decomposition... The gas is discharged from the outlet 122 to the application section. Another part passes through the first flow meter 72 and the first one-way valve 71 and is then merged with the air introduced through the air inlet pipe 80 via the second pipe after passing through the second flow meter 82 and the second one-way valve 81. The mixture reaches the inlet 90 of the premixed gas chamber and is then transported to the premixed gas chamber 22. The mixed gas enters the micro-channel 211 and comes into contact with the hydroxide catalyst layer 212 to carry out a catalytic combustion reaction. The exhaust gas after combustion is collected by the exhaust gas collection chamber 23 and then discharged uniformly from the combustion exhaust gas outlet 231.

[0046] In this embodiment, the microtubular ammonia-hydrogen conversion system has the following advantages: 1. Compared with traditional separate ammonia decomposition reaction devices, the microtube ammonia-hydrogen conversion system provided by the present invention has a compact volume and greatly improved space utilization, providing a feasible solution, especially in mobile applications and space-constrained applications, while traditional separate ammonia decomposition devices cannot meet the above-mentioned application scenarios.

[0047] 2. By combining hydrogen catalytic oxidation and ammonia catalytic decomposition in situ through structural innovation and the optimal selection of catalysts, the heat released by the former reaction is fully utilized to provide heat for the decomposition of the latter, thereby significantly improving the system's energy utilization efficiency and achieving a self-sustaining effect of reaction heat.

[0048] 3. The microtube ammonia-hydrogen conversion system used in this invention is easy to prepare and process, conducive to large-scale production, flexible in integration, easy to seal, simple to disassemble, and convenient for maintenance and improvement.

[0049] 4. The core-shell structure microchannel of this invention couples the exothermic hydrogen catalytic oxidation and the endothermic ammonia catalytic decomposition in situ, requiring no external heating after startup; simultaneously, the hydrogen in the decomposition products undergoes catalytic oxidation, avoiding the difficult-to-ignite ammonia and NO production. X Pollutants, as well as secondary pollution caused by residual ammonia from incomplete combustion, are eliminated, achieving zero carbon emissions, no pollution, and self-heating.

[0050] In summary, the present invention provides a microtube-type ammonia-hydrogen conversion system, comprising a heat exchange device and a reaction device; the heat exchange device includes a cold medium pipe and a hot medium pipe spaced apart; one end of the cold medium pipe is provided with an ammonia raw material inlet, and the other end is provided with a cold medium pipe outlet; one end of the hot medium pipe is provided with a hot medium pipe inlet, and the other end is provided with a first decomposition gas outlet and a second decomposition gas outlet; the reaction device includes a reaction chamber, a premixed gas chamber, and a tail gas collection chamber; the interior of the reaction chamber is provided with a plurality of microchannels; one end of each microchannel communicates with the premixed gas chamber, and the other end communicates with the tail gas collection chamber; the cold medium pipe outlet communicates with the reaction chamber; the second decomposition gas outlet communicates with the premixed gas chamber; the hot medium pipe inlet communicates with the reaction chamber; the inner surface of the microchannel is provided with a hydroxide catalyst layer, and the outer surface of the microchannel is provided with an ammonia decomposition catalyst layer. This invention utilizes a microtube array integrated ammonia decomposition device formed by incorporating several microchannels within the reaction chamber. Part of the hydrogen generated from ammonia decomposition is used for catalytic oxidation within the microtube catalytic reactor to provide heat. Simultaneously, the ammonia catalytic decomposition reaction is heated in situ outside the microtube catalytic reactor. Through system integration and structural design, the exothermic catalytic oxidation and endothermic catalytic decomposition are coupled synchronously, fully utilizing the inherent heat of the reaction without external heating, thus significantly improving energy efficiency. Furthermore, there are no harmful pollutant emissions or carbon emissions. This microtube ammonia-hydrogen conversion system also boasts advantages such as small size and high safety, providing a feasible solution for applications in zero-carbon hydrogen-powered mobile environments and high-space-utilization scenarios.

[0051] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A microtubular ammonia-hydrogen conversion system, characterized in that, Includes heat exchangers and reaction devices; The heat exchange device includes a cold medium pipe and a hot medium pipe arranged at intervals; one end of the cold medium pipe is provided with an ammonia raw material inlet and the other end is provided with a cold medium pipe outlet; one end of the hot medium pipe is provided with a hot medium pipe inlet and the other end is provided with a first decomposition gas outlet and a second decomposition gas outlet. The reaction device includes a reaction chamber, a premixed gas chamber, and a tail gas collection chamber. The reaction chamber has several microchannels inside. One end of each microchannel communicates with the premixed gas chamber, and the other end communicates with the tail gas collection chamber. The outlet of the cold medium pipe communicates with the reaction chamber. The second decomposition gas outlet communicates with the premixed gas chamber. The inlet of the hot medium pipe communicates with the reaction chamber. The inner surface of each microchannel is provided with a hydroxide catalyst layer, and the outer surface of each microchannel is provided with an ammonia decomposition catalyst layer. The tail gas collection chamber has a combustion tail gas outlet. The cold medium pipe and the hot medium pipe are arranged parallel to each other; both the cold medium pipe and the hot medium pipe have an S-shaped structure; the heat exchange device also includes a shell, and the cold medium pipe and the hot medium pipe are disposed inside the shell; a start-up preheater is attached to the inner wall of the shell; the micro-pipe is selected from one of the following: straight round pipe, straight flat pipe, serpentine flat pipe, coiled round pipe, and coiled flat pipe; the inner wall of the reaction chamber is attached with a heat insulation sleeve; the reaction chamber is provided with a reaction chamber outlet, and the reaction chamber outlet is connected to the hot medium pipe inlet through a first pipe; the second decomposition gas outlet is connected to the premixed gas chamber through a second pipe; the second pipe is provided with a first one-way valve and a first flow meter; the second pipe is also provided with an air inlet pipe connection port, the air inlet pipe connection port is connected to an air inlet pipe, and the air inlet pipe is provided with a second one-way valve and a second flow meter. The hydroxide catalyst in the hydroxide catalyst layer is selected from one or more of MgAl2O4, Mn-Co-Cu-Fe-Ni / γ-Al2O3 / cordierite, Pt / γ-Al2O3 / cordierite, and Pt / γ-Al2O3; the ammonia decomposition catalyst in the ammonia decomposition catalyst layer is selected from one or more of Fe-based ammonia decomposition catalyst, Ni-based ammonia decomposition catalyst, and Ru-based ammonia decomposition catalyst. The microtubular ammonia-hydrogen conversion system also includes a heat-insulating base; the heat-insulating base, the heat exchange device, and the reaction device are stacked in sequence from bottom to top to form a layer structure; the gas outlet of the reaction chamber is located diagonally opposite the gas outlet of the cold medium pipe; The inner diameter of the microchannel is ≤2.5mm, and the wall thickness of the microchannel is 0.1mm-2mm.

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