A hydrogen production system by ammonia decomposition

Abstract

The present invention provides an ammonia decomposition hydrogen production system, which relates to the technical field of hydrogen production. The ammonia decomposition hydrogen production system includes: a liquid ammonia storage unit, a primary preheating unit, a secondary preheating unit, an ammonia decomposition unit, an ammonia adsorption unit, a hydrogen purification unit, and a hydrogen storage unit; the liquid ammonia storage unit provides liquid ammonia for the primary preheating unit, the secondary preheating unit is respectively connected to the ammonia decomposition unit and the ammonia adsorption unit, and the gas distribution area of the secondary preheating unit is connected to an air pipeline; the gas in the ammonia decomposition unit is transported into the primary preheating unit and then introduced into the ammonia adsorption unit; the outlet of the ammonia adsorption unit is respectively connected to the secondary preheating unit and the hydrogen purification unit; the hydrogen outlet of the hydrogen purification unit is connected to the hydrogen storage unit, and the waste gas outlet is connected to the secondary preheating unit. The present invention uses electric heating and self-heating to achieve the vaporization and heating of liquid ammonia, and uses ammonia gas and the recycled hydrogen gas to provide part of the heat for ammonia decomposition, thereby improving the heat conversion rate of the entire system.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production, and more particularly to an ammonia decomposition hydrogen production system. Background Art

[0002] The ammonia decomposition hydrogen production technology uses ammonia as raw material, and under the action of ruthenium, nickel, iron, and cobalt catalysts, it is heated to 400 - 1000 °C for decomposition, and a hydrogen-nitrogen mixed gas containing 75% H2 and 25% N2 can be obtained. Then, the hydrogen-nitrogen mixed gas is purified for hydrogen, and finally hydrogen with a purity of 99% - 99.999% can be obtained.

[0003] The current ammonia decomposition devices have great limitations. Because most raw materials use liquid ammonia, and at the same time, ammonia decomposition is an endothermic reaction with a high reaction temperature, a large amount of heat needs to be provided. As a result, the energy consumption of existing devices is very high.

[0004] The prior art generally provides heat through a separate combustion module or an electric heating device, with high energy consumption and high manufacturing costs. Moreover, many current ammonia decomposition hydrogen production systems have problems such as insufficient energy utilization, heat loss, and low conversion rate.

[0005] Therefore, there is a need for a device with a simple structure, efficient heat utilization, and reduced external heat supply. Summary of the Invention

[0006] The present invention aims to solve the problems of insufficient energy utilization, heat loss, and low conversion rate in the existing ammonia decomposition hydrogen production system. In view of the above problems, the present invention provides an ammonia decomposition hydrogen production system, which uses electric heating and self-heating to achieve the vaporization and heating of liquid ammonia, and uses ammonia gas and recycled hydrogen gas to provide part of the heat supply for ammonia decomposition, thereby improving the heat conversion rate of the entire system.

[0007] The technical solution adopted by the present invention is as follows:

[0008] An ammonia decomposition hydrogen production system, comprising: a liquid ammonia storage unit, a primary preheating unit, a secondary preheating unit, an ammonia decomposition unit, an ammonia adsorption unit, a hydrogen purification unit, and a hydrogen storage unit;

[0009] The liquid ammonia storage unit provides liquid ammonia for the primary preheating unit, and the ammonia medium outlet of the primary preheating unit is communicated with the ammonia medium inlet of the secondary preheating unit;

[0010] The ammonia medium outlet of the secondary preheating unit is communicated with the ammonia decomposition unit, and the reaction gas outlet of the catalytic combustion in the secondary preheating unit is communicated with the ammonia adsorption unit; after the reaction gas outlet in the secondary preheating unit is connected to the ammonia adsorption unit, it is discharged through a pipeline; an air inlet pipeline is provided at the air inlet of the secondary preheating unit;

[0011] The ammonia decomposition gas outlet of the ammonia decomposition unit is connected to the inside of the primary preheating unit through a pipeline, and this pipeline passes through the primary preheating unit and is connected to the inside of the ammonia adsorption unit;

[0012] The hydrogen-nitrogen mixed medium outlet of the ammonia adsorption unit is communicated with the inlets of the hydrogen purification unit and the secondary preheating unit; the desorbed gas outlet of the ammonia adsorption unit is communicated with the inlet of the secondary preheating unit;

[0013] The hydrogen outlet of the hydrogen purification unit is communicated with the hydrogen storage unit, and the waste gas outlet of the hydrogen purification unit is connected to the inlet of the secondary preheating unit;

[0014] Wherein, the secondary preheating unit includes:

[0015] A preheating tank, two tube sheets are arranged along the axial direction of the preheating tank, and the two tube sheets divide the inside of the preheating tank into a gas distribution area, a reaction area and an air outlet area;

[0016] The ammonia medium outlet of the ammonia adsorption unit, the waste gas outlet of the hydrogen purification unit and the air inlet pipeline are all connected to the gas distribution area;

[0017] Reaction pipes, installed between the two tube sheets, with both ends respectively communicated with the gas distribution area and the air outlet area, and the reaction pipes are filled with catalysts;

[0018] An ammonia transmission pipeline, installed inside the preheating tank, with both ends extending out of the preheating tank and respectively communicated with the primary preheating unit and the ammonia decomposition unit. The ammonia transmission pipeline located in the reaction area is arranged in a spiral shape and sleeved outside the reaction pipes;

[0019] A heater, arranged in the reaction area;

[0020] A breathable support, arranged in the air outlet area, and an air outlet is formed between the breathable support and the bottom of the preheating tank;

[0021] Packing, filled in the air outlet area;

[0022] Wherein, the gas flow direction in the reaction pipes is opposite to the ammonia flow direction in the ammonia transmission pipeline.

[0023] Optionally, the secondary preheating unit further includes:

[0024] A gas distributor, installed in the gas mixing area of the preheating tank, for distributing the air and waste gas entering the preheating tank.

[0025] Optionally, the secondary preheating unit further includes:

[0026] The heat insulation layer is arranged on the side wall of the reaction area.

[0027] Optionally, the heater is a resistance heating wire, which is arranged in a spiral shape along the axis of the reaction pipeline, and the ammonia delivery pipeline is located inside the resistance heating wire.

[0028] Optionally, the pitch of the resistance heating wire is adjustable.

[0029] Optionally, the catalyst is one of Pt / TiO2, Pd / HZSM-5, CoO2, CuO2, LaMnO3.

[0030] Optionally, the decomposition pipeline of the ammonia decomposition unit is filled with one of Ru, Fe, Co, Ni, Ni-Fe, non-noble metal or bimetallic catalysts.

[0031] Optionally, the ammonia adsorption unit includes:

[0032] An analysis component, whose gas outlet end is communicated with the gas inlet of the hydrogen purification unit and the secondary preheating unit through a pipeline, and whose gas inlet end is communicated with the ammonia decomposition unit;

[0033] A desorption component, whose gas outlet end is communicated with the gas inlet of the secondary preheating unit, and whose gas inlet end is communicated with the ammonia decomposition unit.

[0034] Optionally, the hydrogen purification unit is a PSA pressure swing adsorption device.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. Use electric heating and self-heating to realize the vaporization and heating of liquid ammonia, and use ammonia gas and recycled hydrogen to provide part of the heat supply for ammonia decomposition; reduce the energy consumption of hydrogen production, improve the utilization rate of waste gas, and achieve the purpose of saving energy.

[0037] 2. The gas obtained by high-temperature decomposition of ammonia provides a large amount of heat for ammonia vaporization through the primary preheating unit, reducing the additional heat required for vaporization. Reduce heat loss.

[0038] 3. The desorbed gas of the ammonia adsorption unit and the hydrogen purification unit are all introduced into the catalytic reaction combustion of the secondary preheater for heat supply, improving the utilization rate of thermal energy and reducing energy loss. Description of the Drawings

[0039] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0040] Figure 1 It is a schematic diagram of the overall structure of the ammonia decomposition hydrogen production system.

[0041] Figure 2 It is a schematic diagram of the structure of the secondary preheating unit of the ammonia decomposition hydrogen production system.

[0042] Reference numerals:

[0043] 1. Liquid ammonia storage unit;

[0044] 2. Primary preheating unit;

[0045] 3. Secondary preheating unit; 31. Preheating tank; 32. Tube sheet; 33. Reaction pipeline; 34. Ammonia transmission pipeline; 35. Heater; 36. Permeable support; 37. Packing; 38. Gas distributor; 39. Heat insulation layer;

[0046] 4. Ammonia decomposition unit;

[0047] 5. Ammonia adsorption unit;

[0048] 6. Hydrogen purification unit;

[0049] 7. Hydrogen storage unit. Detailed implementation manners

[0050] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0051] In the present invention, unless otherwise clearly specified and defined, terms such as "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0053] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0054] As Figure 1 and Figure 2 shown, an ammonia decomposition hydrogen production system provided by an embodiment of the present invention includes: a liquid ammonia storage unit 1, a primary preheating unit 2, a secondary preheating unit 3, an ammonia decomposition unit 4, an ammonia adsorption unit 5, a hydrogen purification unit 6, and a hydrogen storage unit 7.

[0055] The liquid ammonia storage unit 1 provides liquid ammonia for the primary preheating unit 2, and the ammonia medium outlet of the primary preheating unit 2 is communicated with the ammonia medium inlet of the secondary preheating unit 3. The ammonia medium outlet of the secondary preheating unit 3 is communicated with the ammonia decomposition unit 4, and the reaction gas outlet of the catalytic combustion of the secondary preheating unit 3 is communicated with the ammonia adsorption unit 5; after the reaction gas outlet of the secondary preheating unit 3 is connected to the ammonia adsorption unit 5, it is discharged through a pipeline; an air inlet pipeline is provided at the air inlet of the secondary preheating unit 3. The ammonia decomposition gas outlet of the ammonia decomposition unit 4 is connected to the primary preheating unit 2 through a pipeline, and this pipeline passes through the primary preheating unit 2 and is connected to the ammonia adsorption unit 5. The hydrogen-nitrogen mixed medium outlet of the ammonia adsorption unit 5 is communicated with the hydrogen purification unit 6 and the air inlet of the secondary preheating unit 3; the desorbed gas outlet of the ammonia adsorption unit 5 is communicated with the air inlet of the secondary preheating unit 3. The hydrogen outlet of the hydrogen purification unit 6 is communicated with the hydrogen storage unit 7, and the waste gas outlet of the hydrogen purification unit 6 is connected to the air inlet of the secondary preheating unit 3.

[0056] The secondary preheating unit 3 includes: a preheating tank 31, a reaction pipeline 33, an ammonia delivery pipeline 34, a heater 35, a breathable support 36, and a filler 37.

[0057] Preheating tank 31, two tube sheets 32 are provided along the axial direction of the preheating tank 31, and the two tube sheets 32 divide the interior of the preheating tank 31 into a gas distribution area, a reaction area and an air outlet area. The ammonia medium outlet of the ammonia adsorption unit 5, the waste gas outlet of the hydrogen purification unit 6 and the air inlet pipe are all connected to the gas distribution area. Reaction pipe 33, installed between the two tube sheets 32, with both ends communicating with the gas distribution area and the air outlet area respectively, and a catalyst is filled in the reaction pipe 33. Ammonia delivery pipe 34, installed in the preheating tank 31, with both ends extending out of the preheating tank 31 and communicating with the primary preheating unit 2 and the ammonia decomposition unit 4 respectively. The ammonia delivery pipe 34 located in the reaction area is arranged in a spiral shape and sleeved outside the reaction pipe 33. Heater 35, arranged in the reaction area. Permeable support 36, arranged in the air outlet area, and an air outlet is formed between the permeable support 36 and the bottom of the preheating tank 31. Packing 37, filled in the air outlet area. Among them, the gas flow direction in the reaction pipe 33 is opposite to the ammonia flow direction in the ammonia delivery pipe 34.

[0058] In use, liquid ammonia first passes through the primary preheating unit 2 for preheating, so that the liquid ammonia and the vaporized liquid ammonia enter the secondary preheating unit 3 at a certain temperature. After passing through the gas in the secondary preheating unit 3, catalytic combustion occurs in the reaction pipe 33, and the heat generated during the catalytic combustion provides the reaction heat for the mixture of liquid ammonia and vaporized liquid ammonia in the ammonia delivery pipe 34. In order to increase the reaction time of the mixture in the ammonia delivery pipe 34, the ammonia delivery pipe 34 located in the reaction area of the preheating pipe is arranged in a spiral shape. The reacted gas enters the ammonia decomposition unit 4 for decomposition to obtain a mixed gas of NH3 + H2 + N2. The decomposed gas is sequentially connected to the primary preheating unit 2 and the ammonia adsorption unit 5 through pipes. Since the decomposed gas has a certain amount of heat, it is first discharged into the primary preheating unit 2 to preheat the liquid ammonia in the primary preheating unit 2, and then enters the ammonia adsorption unit 5 for adsorption. The waste gas after the catalytic combustion reaction of the secondary preheating unit 3 is connected to the ammonia adsorption unit 5 through a pipe to provide heat for the ammonia adsorption unit 5. The mixed gas entering the ammonia adsorption unit 5 through the ammonia decomposition unit 4 is adsorbed and desorbed in the ammonia adsorption unit 5. Part of the hydrogen-nitrogen mixed gas obtained after adsorption is discharged into the hydrogen purification unit 6, and part is discharged into the secondary preheating unit 3; the ammonia obtained after desorption is discharged into the secondary preheating unit 3 through a pipe to provide fuel for the catalytic combustion of the secondary preheating unit 3. Considering the heat requirement of the ammonia adsorption unit, a part of the hydrogen-nitrogen mixed gas can be separated and enter the secondary preheating unit 3 to participate in catalytic combustion according to the magnitude of the required heat, as a heat supplement for the ammonia adsorption unit. The hydrogen purified by the hydrogen purification unit 6 enters the hydrogen storage unit 7 for storage. Another part of the purified gas is discharged into the secondary preheating unit 3 through a pipe. At the same time, an air pipe is also connected in the secondary preheating unit 3 to provide sufficient combustible gas for subsequent catalytic combustion.

[0059] It should be noted that the inlet of the catalytic combustion pipe of the secondary preheating unit 3 is connected to the waste gas outlet of the hydrogen purification unit 6, the medium outlet of the ammonia adsorption unit 5, and the air inlet through a multi-way pipe. Therefore, most of the gas in the medium outlet of the ammonia adsorption unit 5 is discharged into the hydrogen purification unit 6.

[0060] The more specific working principle of the secondary preheating unit 3:

[0061] The preheated liquid ammonia enters the preheating tank 31 from the bottom through the ammonia delivery pipe 34. The catalyst is filled in the reaction pipe 33. The gas enters the gas distribution area through the top of the preheating tank 31 and is shunted by the gas distributor 38 in the gas distribution area to avoid directly impacting into the reaction pipe 33. At this time, the heater 35 operates to provide the reaction temperature for the contact between the gas and the catalyst. Since the liquid ammonia entering the preheating tank 31 has a certain temperature, it raises the temperature inside the preheating tank 31, and the flow direction of the liquid ammonia is opposite to that of the gas. Therefore, the operating energy consumption of the heater 35 can be correspondingly reduced, achieving the purpose of reducing energy consumption.

[0062] It should be further noted that the ammonia delivery pipe 34 is arranged in a spiral shape to increase the residence time of ammonia in the preheating pipe, so that the liquid ammonia in the ammonia delivery pipe 34 is fully vaporized.

[0063] The packing 37 is ceramic balls. Filling ceramic balls in the gas outlet area is to support the tube sheet 32. At the same time, the gas after the reaction passes through the ceramic balls and enters the breathable support 36 and then is discharged from the preheating tank 31.

[0064] In another embodiment, as Figure 2 shown, in order to improve the mixing uniformity of multiple media, a gas distributor 38 is provided at the inlet of the preheating pipe, which facilitates the mixing of the gases discharged from the hydrogen purification unit 6 and the ammonia adsorption unit 5 with air. After being shunted, the mixed gas fills the entire gas mixing area.

[0065] In another embodiment, as Figure 2 shown, in order to improve the heat preservation performance of the preheating pipe, a heat preservation layer 39 is provided on the inner side wall of the reaction area of the preheating tank 31. The heat preservation layer 39 is made of ceramic fiber cotton.

[0066] In another embodiment, as Figure 2 shown, in order to facilitate heating of the preheating tank 31, the heater 35 is a resistance heating wire.

[0067] In one of the implementation manners, the resistance heating wire is arranged in a spiral shape along the axis of the reaction pipe 33, and the ammonia delivery pipe 34 is located inside the resistance heating wire. The pitch of the resistance heating wire is adjustable.

[0068] In another implementation manner, there are multiple heating resistance wires, which are vertically enclosed into an annular structure and enclose the outside of the reaction pipe 33.

[0069] In another embodiment, the catalyst is one of Pt / TiO2, Pd / HZSM-5, CoO2, CuO2, LaMnO3.

[0070] Put a catalyst (the catalyst is one of Pt / TiO2, Pd / HZSM-5, CoO2, CuO2, LaMnO3) in the reaction pipe 33 of the preheating pipe. The ammonia delivery pipe 34 spirally surrounds the outside of the reaction pipe 33, so that ammonia can fully absorb the heat of catalytic combustion. The electric heating is mainly to provide initial heat for catalytic combustion in the early stage. When the heat of catalytic combustion is sufficient, the electric heating can be turned off. When catalytic combustion occurs in the reaction pipe 33, the combustion gas is a mixture of hydrogen, nitrogen, air and a small amount of ammonia.

[0071] At the same time, since the reaction pipe 33 is a straight pipe, it is convenient to replace the catalyst later. When replacing the catalyst, remove the air-permeable support 36 at the bottom. Due to gravity, the porcelain balls flow out of the preheating pipe first, and finally the catalyst is discharged through the bottom. When placing the catalyst, first load the porcelain balls into the gas outlet area, and then load the catalyst into the reaction pipe 33.

[0072] In another embodiment, the decomposition pipe of the ammonia decomposition unit 4 is filled with one of Ru, Fe, Co, Ni, Ni-Fe, non-precious metals or bimetallic catalysts.

[0073] Ammonia has absorbed a large amount of heat before entering the ammonia decomposition unit 4. Therefore, during the decomposition reaction, the reactor in the ammonia decomposition unit 4 only needs to be electrically heated to provide a small amount of heat to reach its decomposition temperature. The ammonia decomposition catalyst can be selected from one of noble metals, non-precious metals or bimetallic catalysts such as Ru, Fe, Co, Ni, Ni-Fe, etc. This reduces the power consumption and at the same time has the advantage of a simple process. The decomposed gas enters the primary preheating unit 2 and the hydrogen purification unit 6 to supply heat for their desorption.

[0074] In another embodiment, as Figure 1 shown, the ammonia adsorption unit 5 includes:

[0075] An analysis component, whose gas outlet end is connected to the gas inlet of the hydrogen purification unit 6 and the secondary preheating unit 3 through a pipe, and whose gas inlet end is connected to the ammonia decomposition unit; a desorption component, whose gas outlet end is connected to the gas inlet of the secondary preheating unit 3, and whose gas inlet end is connected to the ammonia decomposition unit 4.

[0076] When the mixture of NH3 + H2 + N2 enters the ammonia adsorption unit 5, a part of the gas is analyzed by the analysis component, and the analyzed gas (the analyzed gas refers to the mixture of NH3 that has been removed) is discharged into the secondary preheating unit 3 to provide waste heat and combustible gas for the subsequent catalytic combustion. The desorption component desorbs the mixed gas, and the desorbed hydrogen-nitrogen mixed gas is discharged into the hydrogen purification unit 6 for purification.

[0077] In another embodiment, the outlet of the desorbed gas is connected to the hydrogen purification unit 6 and the secondary preheating unit 3 through a tee, and a metering valve is provided on the pipeline of the secondary preheating unit 3 to facilitate the adjustment of the hydrogen-nitrogen mixed gas entering the secondary preheating unit 3. More specifically, it is adjusted according to the heat required in the ammonia adsorption unit 5 section. Since a part of the hydrogen-nitrogen mixed gas can be used for catalytic combustion reaction, and the other part provides heat supplement for the ammonia adsorption unit 5.

[0078] It should be further noted that the ammonia adsorption unit 5 is set with 2 towers or multiple towers for adsorption according to the scale of the device. While one tower completes the NH3 adsorption and outputs the product gas of H2+N2, the other towers are performing the NH3 desorption process.

[0079] In another embodiment, the hydrogen purification unit 6 is a PSA pressure swing adsorption device. The hydrogen purification unit 6 uses a PSA pressure swing adsorption device to purify hydrogen, so that the hydrogen purity can reach 99% - 99.999%. The desorbed gas is then introduced into the secondary preheating unit 3 for catalytic combustion.

[0080] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hydrogen production system by ammonia decomposition, comprising: A liquid ammonia storage unit, a primary preheating unit, a secondary preheating unit, an ammonia decomposition unit, an ammonia adsorption unit, a hydrogen purification unit, and a hydrogen storage unit; characterized in that, The liquid ammonia storage unit provides liquid ammonia for the primary preheating unit, and the ammonia medium outlet of the primary preheating unit is communicated with the ammonia medium inlet of the secondary preheating unit; The ammonia medium outlet of the secondary preheating unit is communicated with the ammonia decomposition unit, and the reaction gas outlet of the catalytic combustion in the secondary preheating unit is communicated with the ammonia adsorption unit; after the reaction gas outlet in the secondary preheating unit is connected to the ammonia adsorption unit, it is discharged through a pipeline; an air inlet pipeline is provided at the air inlet of the secondary preheating unit; The ammonia decomposition gas outlet of the ammonia decomposition unit is connected to the primary preheating unit through a pipeline, and this pipeline passes through the primary preheating unit and is connected to the ammonia adsorption unit; The hydrogen-nitrogen mixed medium outlet of the ammonia adsorption unit is communicated with the hydrogen purification unit and the air inlet of the secondary preheating unit; the desorbed gas outlet of the ammonia adsorption unit is communicated with the air inlet of the secondary preheating unit; The hydrogen outlet of the hydrogen purification unit is communicated with the hydrogen storage unit, and the waste gas outlet of the hydrogen purification unit is connected to the air inlet of the secondary preheating unit; Wherein, the secondary preheating unit includes: A preheating tank, two tube sheets are provided along the axis of the preheating tank, and the two tube sheets divide the inside of the preheating tank into a gas distribution area, a reaction area, and an air outlet area; The ammonia medium outlet of the ammonia adsorption unit, the waste gas outlet of the hydrogen purification unit, and the air inlet pipeline are all connected to the gas distribution area; A reaction pipeline, installed between the two tube sheets, with its two ends respectively communicated with the gas distribution area and the air outlet area, and a catalyst is filled in the reaction pipeline; An ammonia delivery pipeline, installed inside the preheating tank, with its two ends extending out of the preheating tank and respectively communicated with the primary preheating unit and the ammonia decomposition unit. The ammonia delivery pipeline located in the reaction area is arranged in a spiral shape and sleeved outside the reaction pipeline; A heater, arranged in the reaction area; A breathable support, arranged in the air outlet area, and an air outlet is formed between the breathable support and the bottom of the preheating tank; Packing, filled in the air outlet area; Wherein, the gas flow direction in the reaction pipeline is opposite to the ammonia flow direction in the ammonia delivery pipeline.

2. The ammonia decomposition hydrogen production system according to claim 1, characterized in that The secondary preheating unit further includes: A gas distributor, installed in the gas mixing area of the preheating tank, for distributing the air and waste gas entering the preheating tank.

3. The ammonia decomposition hydrogen production system according to claim 1 or 2, characterized in that, The secondary preheating unit further includes: A heat insulation layer, arranged on the side wall of the reaction area.

4. The ammonia decomposition hydrogen production system according to claim 3, wherein The heater is a resistance heating wire, and the resistance heating wire is arranged in a spiral shape along the axis of the reaction pipeline, and the ammonia delivery pipeline is located inside the resistance heating wire.

5. The ammonia decomposition hydrogen production system according to claim 4, characterized in that, The pitch of the resistance heating wire is adjustable.

6. The ammonia decomposition hydrogen production system according to claim 1, wherein, The catalyst is one of Pt / TiO2, Pd / HZSM-5, CoO2, CuO2, LaMnO3.

7. The ammonia decomposition hydrogen production system according to claim 1, wherein One of non-noble metals or bimetallic catalysts is filled in the decomposition pipeline of the ammonia decomposition unit.

8. The ammonia decomposition hydrogen production system according to claim 1, characterized in that, The ammonia adsorption unit includes: The analysis component, its gas outlet is communicated with the inlets of the hydrogen purification unit and the secondary preheating unit through pipelines, and its gas inlet is communicated with the ammonia decomposition unit.

9. The ammonia decomposition hydrogen production system according to claim 1, characterized in that, The hydrogen purification unit is a PSA pressure swing adsorption device.

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