A hydrogen production membrane reactor based on a biomimetic structure

Abstract

The application is suitable for the field of ammonia cracking hydrogen production technology, and provides an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure, which comprises an adiabatic shell and a biomimetic reactor module arranged in the adiabatic shell; the biomimetic reactor module comprises a main gas inlet pipeline, a central pipeline and multiple-stage reaction branch pipelines, each reaction branch pipeline has a Y-shaped fractal topological structure, a catalyst carrier is arranged in each reaction branch pipeline, and a hydrogen separation pipeline with a built-in hydrogen selective separation membrane is connected to each reaction branch pipeline at a bifurcation; a heating module is arranged outside each reaction branch pipeline, and a temperature sensor, a pressure sensor and a hydrogen concentration sensor are arranged at the bifurcation. The device strengthens heat transfer and reaction through a biomimetic fractal structure, realizes reaction-separation integration and process intelligent control, and has the advantages of high ammonia conversion efficiency, high hydrogen recovery rate, compact structure, stable and reliable operation and the like.

Description

Technical Field

[0001] This invention belongs to the field of ammonia cracking hydrogen production technology, and particularly relates to an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure. Background Technology

[0002] Hydrogen energy, as a multi-faceted alternative to fossil fuels, is widely regarded as one of the most promising energy sources of the 21st century, capable of playing a crucial role in driving the world toward decarbonization. The large-scale application of hydrogen energy involves multiple stages, including hydrogen production, fission, purification, and storage. Among various hydrogen storage carriers, ammonia possesses advantages such as high hydrogen density, ease of liquid storage, and high storage and transportation safety; therefore, ammonia cracking for hydrogen production technology has been extensively studied.

[0003] Ammonia decomposition is an endothermic reaction, requiring a high temperature to be maintained to achieve high conversion rates. Maintaining this temperature necessitates a continuous input of significant energy. Therefore, current research focuses on using hot air heat exchange, direct fuel combustion, or electric heating. However, due to the low thermal conductivity of the catalyst carrier, heat transfer from the reactor wall to the center is inefficient, easily leading to axial and radial temperature gradients. This results in uneven reaction, with the central region potentially experiencing lower conversion rates due to insufficient temperature. Therefore, optimizing the reactor structure is currently under extensive research. Many patents propose novel reactor designs, such as microchannel reactors. By reducing channel size, these reactors significantly enhance heat and mass transfer efficiency, enabling rapid heating and uniform temperature control. However, this type of reactor increases flow resistance, and the uneven ammonia flow rate across channels results in sections with very little ammonia flowing through them, leading to lower catalyst utilization, reduced overall efficiency, and susceptibility to clogging by impurities.

[0004] Regarding the issue that hydrogen gas inhibits the ammonia decomposition reaction, some studies have designed ammonia decomposition membrane reactors, which couple a separation membrane within the device to achieve ammonia cracking while separating purified hydrogen gas, thereby improving reaction efficiency. However, existing studies often involve arranging separation membranes such as palladium membranes within the entire reaction tube, which presents problems such as high cost and installation difficulties. Summary of the Invention

[0005] The purpose of this invention is to provide a biomimetic membrane reactor for ammonia cracking to produce hydrogen, which aims to solve the problems mentioned in the background art.

[0006] The present invention is implemented as follows: an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure includes an insulating shell, on which a hot air inlet and a hot air outlet are provided, and further includes:

[0007] The biomimetic reactor module includes a main air inlet pipe, a central pipe, and various levels of reaction branch pipes employing a Y-shaped fractal topology channel structure. The main air inlet pipe and the central pipe are respectively located at both ends of the insulating shell. Each level of reaction branch pipe extends downwards with two branches at bifurcations. The Y-shaped fractal topological channel structure is arranged in a tree-like distribution with acute angles. Catalyst carriers are arranged in the main reaction channels of each level of reaction branch pipe. After the catalyst carriers of each level of reaction branch pipe and before the bifurcation, a cavity is set. Hydrogen separation pipes are set at the bifurcation of each level of reaction branch pipe, and hydrogen selective separation membranes are set at the inlet end of the hydrogen separation pipes. The outlet end of each hydrogen separation pipe is connected to the central pipe.

[0008] A heating module is connected to each stage of the reaction branch pipe, and the heating module is used to controllably heat each stage of the reaction branch pipe.

[0009] A further technical solution is that the reaction branch pipe includes several primary reaction branch pipes connected to the main air intake pipe, each primary reaction branch pipe is connected to two secondary reaction branch pipes, each secondary reaction branch pipe is connected to two tertiary reaction branch pipes, and a catalyst carrier is provided in each of the primary, secondary, and tertiary reaction branch pipes. Hydrogen separation pipes are provided at the bifurcation points of the primary and secondary reaction branch pipes, the bifurcation points of the secondary and tertiary reaction branch pipes, and the ends of the tertiary reaction branch pipes. A hydrogen selective separation membrane is provided at the inlet end of each hydrogen separation pipe, and the outlet end of each hydrogen separation pipe is connected to the central pipe.

[0010] An exhaust pipe is also provided at the connection between the central pipe and the insulating shell, and the ends of each of the three-stage reaction branches are connected to the exhaust pipe through pipelines.

[0011] In a further technical solution, an inner heat-insulating shell is provided inside the outer heat-insulating shell, and the central pipe is located in the inner heat-insulating shell.

[0012] In a further technical solution, the hydrogen selective separation membrane is a palladium membrane.

[0013] A further technical solution also includes a sensor unit, which includes a temperature sensor, a pressure sensor, and a hydrogen concentration sensor disposed at the branches of each stage of the reaction branch pipe.

[0014] In a further technical solution, the heating module includes resistance wires wound around the outer wall of each stage of the reaction branch pipe, and resistance wire terminals mounted on the heat insulation shell.

[0015] A further technical solution is that the first Y-shaped fractal topological channel structure Layer and first Channel length between layers and The ratio, and the first Layer and first Hydraulic diameter of the channel between layers and The ratios are all constant values, expressed as follows:

[0016] ;

[0017] ;

[0018] in, This indicates how many branches are under each level of the channel, and the reaction branches at each level. .

[0019] A further technical solution is that the bifurcation angle The range of values ​​is .

[0020] In a further technical solution, the catalyst support in the primary reaction branch is a spherical particle packed bed, and the catalyst supports in the secondary and tertiary reaction branches are both honeycomb catalyst supports.

[0021] A further technical solution involves adjusting the system based on data collected from various sensors. The hydrogen concentration sensor within the cavity measures the actual hydrogen concentration produced in the upstream reaction zone and compares it with the theoretically expected value calculated using the designed conversion rate. If the concentration deviation is... The heating module is activated and provides supplemental heating at 70%-100% power, while temperature and pressure sensors continuously monitor the temperature. and pressure ,like or Immediately stop heating; if the concentration deviation value is... At this time, the heating module operates at 0-70% power; if the concentration deviation value At this time, there is no need to start the heating module; if the cavity is... At this time, the heating module is turned on to assist heating; if the cavity is... At this point, it is necessary to increase the intake pressure.

[0022] The ammonia cracking hydrogen production membrane reactor based on a biomimetic structure provided in this invention has the following beneficial effects:

[0023] (1) High-efficiency heat transfer and reaction integration: The biomimetic branching Y-shaped fractal topology channel structure is adopted, which extends step by step, significantly increasing the heat transfer surface area, enhancing the radial heat transfer capacity, and improving the temperature uniformity and heat utilization efficiency in the reactor. The fractal structure design can achieve uniform fluid distribution with lower flow resistance, effectively reducing pressure drop along the flow path and improving system energy efficiency.

[0024] (2) Integrated staged catalysis and separation: By setting up three-stage reaction zones of high temperature, medium temperature and low temperature, and combining different forms of catalyst carriers, the reaction conditions can be precisely controlled. Hydrogen separation pipelines and hydrogen selective separation membranes are set after each stage of reaction branch pipes, so that the reaction and hydrogen separation can be carried out simultaneously, thereby improving the ammonia conversion rate and hydrogen recovery efficiency.

[0025] (3) Intelligent control and stable operation: By integrating temperature sensors, pressure sensors and hydrogen concentration sensors, combined with a controllable heating module, the reaction conditions can be monitored and automatically adjusted in real time. The heating power can be intelligently started or adjusted according to the hydrogen concentration deviation, and temperature and pressure safety thresholds are set to ensure that the reaction process operates within a high-efficiency and safe range, avoiding catalyst deactivation and equipment damage.

[0026] (4) Compact structure and good adaptability: The biomimetic fractal structure realizes multi-stage reaction and separation in a limited space. The device has a compact structure and is suitable for hydrogen production scenarios of different scales. The number of branch pipes, the length of the catalyst section and the cavity size can be flexibly designed and adjusted according to the gas flow rate and reaction requirements, which has good process adaptability and scalability.

[0027] (5) Energy saving and easy operation: Heat recovery is achieved by utilizing the temperature gradient formed by the hot air inlet and outlet, and the heat loss is reduced by the insulation of the central hydrogen pipeline by the inner shell. Vacuum pumping is used on the outside of the hydrogen separation membrane to maintain the pressure difference between the inside and outside of the membrane, which improves the hydrogen permeation efficiency. The overall system has low energy consumption and is easy and reliable to operate and control. Attached Figure Description

[0028] Figure 1 A schematic diagram of a biomimetic membrane reactor for ammonia cracking to produce hydrogen is provided in an embodiment of the present invention.

[0029] Figure 2 This invention provides a region partitioning diagram of a Y-shaped fractal topological channel structure in an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure, as provided in an embodiment of the invention.

[0030] Figure 3 A control logic diagram of an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure is provided for an embodiment of the present invention.

[0031] Figure 4A design logic diagram of an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure is provided for an embodiment of the present invention.

[0032] Figure 5 A left view of the structure of an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure, provided in an embodiment of the present invention;

[0033] Figure 6 for Figure 1 Enlarged view of point A in the image;

[0034] Figure 7 for Figure 1 Enlarged view of point B in the image;

[0035] Figure 8 for Figure 1 Enlarged view of point C in the image;

[0036] Figure 9 for Figure 1 Enlarged view of point D in the image;

[0037] Figure 10 This is a schematic diagram of a branch of a Y-shaped fractal topological channel structure in an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure, provided as an embodiment of the present invention (where A1, A2, A3 and A4 represent the three-stage reaction branches of different branches).

[0038] In the attached diagram: 1-Insulated outer shell; 2-Insulated inner shell; 3-Main intake pipe; 4-First-stage reaction branch pipe; 5-Second-stage reaction branch pipe; 6-Third-stage reaction branch pipe; 7-Central pipe; 8-Resistance wire terminal; 9-Resistance wire; 10-Hydrogen separation pipe; a-Hydrogen selective separation membrane; b-Temperature sensor; c-Pressure sensor; d-Hydrogen concentration sensor. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0041] like Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 and Figure 10As shown, an embodiment of the present invention provides an ammonia cracking hydrogen production membrane reactor based on a biomimetic structure, comprising an insulating shell 1, wherein the insulating shell 1 is provided with a hot air inlet and a hot air outlet, and further comprising:

[0042] The biomimetic reactor module includes a main air inlet pipe 3 and a central pipe 7, which are respectively located at both ends of the insulating shell 1. The end of the main air inlet pipe 3 inside the insulating shell 1 is connected to several primary reaction branches 4 (high-temperature reaction zones). Each primary reaction branch 4 is connected to two secondary reaction branches 5 (medium-temperature reaction zones), and each secondary reaction branch 5 is connected to two tertiary reaction branches 6 (low-temperature reaction zones). A catalyst carrier is provided in each of the primary reaction branches 4, secondary reaction branches 5, and tertiary reaction branches 6. Hydrogen separation pipes 10 are provided at the bifurcation points of branch pipe 4 and secondary reaction branch pipe 5, the bifurcation points of secondary reaction branch pipe 5 and tertiary reaction branch pipe 6, and the end of tertiary reaction branch pipe 6. A hydrogen selective separation membrane a is provided at the inlet end of each hydrogen separation pipe 10. The outlet end of each hydrogen separation pipe 10 is connected to the central pipe 7. An inner heat insulation shell 2 is also provided inside the heat insulation shell 1. The central pipe 7 is located in the inner heat insulation shell 2. An exhaust pipe is also provided at the connection point between the central pipe 7 and the heat insulation shell 1. The end of each tertiary reaction branch pipe 6 is connected to the exhaust pipe through a pipeline.

[0043] The heating module is connected to the primary reaction branch pipe 4, the secondary reaction branch pipe 5, and the tertiary reaction branch pipe 6. The heating module is used to controllably heat the primary reaction branch pipe 4, the secondary reaction branch pipe 5, and the tertiary reaction branch pipe 6.

[0044] In this embodiment of the invention, the design of the biomimetic reactor module is inspired by the branching structure of a tree branch, employing a Y-shaped fractal topological channel structure with reaction branches at each level. Each layer of the reaction branch extends downwards with two branches, and the branching angle is... With acute angles, the Y-shaped fractal topology channel structure exhibits a tree-like distribution. Its heat transfer performance depends on the channel height, fractal order, channel length, and bifurcation angle. From the perspective of [the specific angle], a staged reaction mode is adopted, with catalyst supports arranged in the main reaction channels of each stage of the reaction branch pipes. As the pipe diameter gradually decreases, not only is radial heat transfer enhanced in each pipe, but the heat transfer surface area is also greatly increased within a limited space. The hydrogen selective separation membrane a uses a palladium membrane, which is currently widely used. Furthermore, a cavity is left after the catalyst support in each stage of the reaction branch pipe and before the branching point for mixed gas separation and ammonia pretreatment (preheating and temporary storage).

[0045] In operation, ammonia gas is diverted in the main inlet pipe 3 and enters the first-stage reaction branch pipe 4. In the high-temperature reaction zone, it decomposes on the catalyst carrier to produce nitrogen and hydrogen. The unreacted mixture of ammonia, hydrogen, and nitrogen then enters the cavity at the rear of the first-stage reaction branch pipe 4. Within this cavity, hydrogen is separated by a hydrogen selective separation membrane a and then extracted through the central pipe 7 by a vacuum pump. The remaining ammonia and nitrogen continue into the second-stage reaction branch pipe 5 (medium-temperature reaction zone), where they react and separate on the catalyst carrier before entering the tertiary reaction branch pipe 6 (low-temperature reaction zone). Here, hydrogen is separated by the hydrogen selective separation membrane a and introduced into the central pipe 7. The remaining mixture is discharged through another branch. Since the central pipe 7, which separates hydrogen, does not require high-temperature heating, it is isolated by an insulating inner shell 2.

[0046] like Figure 1 , Figure 6 , Figure 7 and Figure 8 As shown, in a preferred embodiment of the present invention, a sensor unit is also included, which includes a temperature sensor b, a pressure sensor c, and a hydrogen concentration sensor d disposed at the branches of each stage of the reaction branch pipe.

[0047] In this embodiment of the invention, the hydrogen concentration sensor d monitors the hydrogen content in the mixed gas. During the reaction process, if the temperature sensor b detects that the reaction temperature is insufficient and the hydrogen concentration sensor d detects that the ammonia conversion rate is low, heat is supplemented by the heating module. The pressure sensor c is used to monitor the gas pressure and calculate the partial pressure of hydrogen in the cavity, thereby obtaining the pressure difference between the inside and outside of the membrane.

[0048] like Figure 1 , Figure 6 , Figure 7 and Figure 8 As shown, in a preferred embodiment of the present invention, the heating module includes resistance wire 9 wound around the outer wall of each reaction branch pipe, and resistance wire terminals 8 installed on the heat insulation shell 1.

[0049] In this embodiment of the invention, a DC power supply is connected through the resistance wire terminal 8, thereby controlling the resistance wire 9 to heat the reaction branch pipes at each stage.

[0050] like Figures 2-4 As shown, in a preferred embodiment of the present invention, the Y-shaped fractal topological channel structure of the biomimetic reactor module, under normal circumstances, is... Layer and first Channel length between layers and The ratio, and the first Layer and first Hydraulic diameter of the channel between layers and The ratios are all constant values, expressed as follows:

[0051] ;

[0052] ;

[0053] in, This indicates how many branches there are under each level of the channel; k = 0, 1, 2.

[0054] In this device, after ammonia gas flows into the main pipeline, it is first divided into three streams into three primary reaction branch pipes 4. The specific number of branch pipes can be adjusted according to the ammonia gas flow rate and pipe diameter. The initial ammonia gas flow rate... At that time, after flowing into the main pipeline, it directly enters the reaction branch pipes at each level, with the optimal initial pipe diameter. ; At this point, after flowing into the main pipeline, it splits into two paths and enters the reaction branch pipes at each stage. The optimal initial pipe diameter... ; At this point, after flowing into the main pipeline, it splits into three branches that enter the reaction branch pipes at each level. The optimal initial pipe diameter... The lower level of each reaction branch has only two branches, at this time .

[0055] bifurcation angle The optimal range is At this point, the performance coefficient of the device can reach 12-13 times that of a linear channel. The enhanced heat transfer is due to increased radial heat transfer and surface area, and at the branching points, fluid separation and reattachment occur, resulting in better mixing of hot and cold fluids. Furthermore, while ensuring full utilization of the target heat exchange space, the fractal structure can distribute the fluid in a smooth and gradual flow pattern from a single inlet to the entire target space via the shortest path, thereby greatly reducing flow resistance along the path.

[0056] As a preferred embodiment of the present invention, since hot air blows directly at the first-stage reaction branch 4, the reaction temperature is the highest, the heat flux is the largest, and the ammonia concentration is the highest, which can withstand a high pressure drop. Therefore, the catalyst support in the first-stage reaction branch 4 adopts the form of a spherical particle packed bed (good heat and mass transfer effect, but high pressure drop). At this time, there are more active sites of the catalyst per unit volume, which are more fully in contact with ammonia and have a higher ammonia decomposition efficiency.

[0057] In the secondary reaction branch 5, the temperature of ammonia gas is relatively low and its concentration is low after the primary reaction. At this time, it is necessary to reduce the bed flow resistance. Therefore, a honeycomb catalyst support (with extremely low pressure drop) is used.

[0058] In the third-stage reaction branch 6, the ammonia concentration is very low, and it is located at the hot air outlet, resulting in a lower temperature compared to the previous two reaction zones. Therefore, a honeycomb catalyst support with high porosity is used. Finally, the length of the catalyst section in each catalytic reaction zone is calculated, thereby achieving efficient utilization of the catalyst in each stage of the reaction branch.

[0059] Given the initial ammonia flow rate, the length of each catalyst section is calculated based on the conversion requirements of each catalyst section. The ammonia volumetric flow rate under the reaction conditions is also considered. The calculation formula is as follows:

[0060] ;

[0061] in, The molar flow rate of ammonia under standard conditions is expressed in mol / s. The reaction temperature is K.

[0062] Approximating the flow in the reactor as plug flow, and using a first-order reaction kinetic model, the reaction space-time for this segment is obtained as follows:

[0063] ;

[0064] in, Represents the reaction rate constant (s) -1 (The catalyst used was determined through experiments or by consulting literature) value); This represents the cumulative conversion rate from the previous section. This represents the cumulative conversion rate at the end of this segment.

[0065] Considering that other factors may influence the actual reaction process; Therefore;

[0066] ;

[0067] in, The impact factor is 1.2-1.4. This refers to the reaction space time in the actual reaction process.

[0068] If the spherical particles in the first-stage reaction branch 4 are approximated as solid volumes, then the catalyst volumes in each section are:

[0069] ;

[0070] Catalyst section length:

[0071] ;

[0072] ;

[0073] in, The diameter of the reaction branch pipe; The porosity of the catalyst support; The length of the catalyst support; This refers to the cross-sectional area of ​​the catalyst support. This refers to the carrier space volume of the catalyst section; the corresponding reaction branch pipes at each stage. .

[0074] In the primary reaction branch 4 In secondary reaction branch 5 and tertiary reaction branch 6, the following conditions are met: ,in This refers to the length of the catalyst carrier within the next-level main pipeline.

[0075] In a preferred embodiment of the present invention, after passing through each catalyst support, the ammonia gas consists of unreacted ammonia, hydrogen, and nitrogen. A cavity is designed at this point to ensure uniform gas mixing, regulate flow rate, and buffer pressure, creating suitable flow conditions for subsequent hydrogen separation. Additionally, this cavity preheats the ammonia gas, ensuring it has a higher initial temperature before entering the next reaction zone.

[0076] To ensure uniform gas mixing, the axial residence time of the gas must be greater than or equal to [amount missing]. The radial diffusion time is multiplied by a factor of 0.5 to 1 (mixing coefficient, valued at 0.5-1), and the design calculation of the separation section cavity is performed accordingly.

[0077] Catalyst section outlet gas velocity:

[0078] ;

[0079] ;

[0080] ;

[0081] in, The molar flow rate of the mixed gas at the catalyst section outlet (mol / s); The molar flow rate of hydrogen (values ​​are given) ); The molar volume at 450℃ is 59.3 L / mol. This refers to the volumetric flow rate of the mixed gas at the catalyst section outlet. The outlet gas velocity is the catalyst section gas velocity.

[0082] Radial diffusion time :

[0083] ;

[0084] Where D is the average gas diffusion coefficient.

[0085] Axial dwell time :

[0086] ;

[0087] in, This is the length of the cavity segment.

[0088] To ensure sufficient mixing of the gas concentration at the membrane inlet in the radial direction, the following requirements must be met:

[0089] ;

[0090] in, The mixing coefficient is (0.5-1).

[0091] Cavity length :

[0092] ;

[0093] As a preferred embodiment of the present invention, the design of the hydrogen separation pipelines 10 at each stage is based on the results of previous studies on hydrogen permeation membrane kinetics. The precise equation for the hydrogen permeation flux of the hydrogen selective separation membrane a can be expressed as:

[0094] ;

[0095] ;

[0096] in, Hydrogen flux (mol H2 / (m)) 2 s)); and These are the partial pressures (Pa) on the inner and outer sides of the hydrogen selective separation membrane a, respectively. The thickness (m) of hydrogen selective separation membrane a (the thickness of commonly used self-supporting membranes is 15-100 μm); It is a constant, with a value of 0.62; The empirical formula for permeability coefficient; The temperature of the palladium film is (K).

[0097] The partial pressure of hydrogen on the inner side of the hydrogen selective separation membrane a can be calculated based on the initial ammonia pressure and the conversion efficiency of each stage. Since a vacuum pump is installed in the exhaust pipe to continuously pump gas, the pressure on the outer side of the membrane can be approximated as 0.

[0098] Calculate the area of ​​hydrogen selective separation membrane a based on hydrogen permeation. :

[0099] ;

[0100] in, This represents the percentage of hydrogen gas that can be separated in the design.

[0101] Because the angle between the hydrogen separation pipe 10 and the reaction branch pipes at each stage is also... (Taking 45°), the interface is therefore an ellipse, and its cross-sectional area is equal to the membrane area. Therefore, the following formula can be obtained:

[0102] ;

[0103] in, The diameter of the hydrogen separation pipe 10.

[0104] In a preferred embodiment of the present invention, the electronic control unit (ECU) regulates the device based on data collected by the sensor unit from various sensors (temperature sensor b, pressure sensor c, and hydrogen concentration sensor d). The hydrogen concentration sensor d inside the cavity measures the actual hydrogen concentration generated in the front-end reaction zone and compares it with the expected value theoretically calculated through the design conversion rate.

[0105] ;

[0106] in, This is the concentration deviation value. This is the measured value from the hydrogen concentration sensor in this section.

[0107] If concentration deviation value At this point, the conversion efficiency is very low, so the heating module is turned on and provides supplemental heating at a higher power (70-100%). Meanwhile, the temperature sensor b and pressure sensor c inside the cavity are constantly monitoring the temperature. and pressure ,like or Immediately stop heating to prevent excessive temperature and pressure from deactivating the catalyst; if the concentration deviation is... At this point, the conversion rate is low, and the heating module assists by operating at low power (0-70%); if the concentration deviation value... At this time, there is no need to activate the heating module. If the cavity is... If the temperature is too low at this point, the heating module needs to be turned on for auxiliary heating; if the cavity is... At this point, it is necessary to increase the intake pressure.

[0108] In this embodiment of the invention, the number of staged reaction zones is first determined based on the required ammonia flow rate. Then, the channel length and hydraulic diameter of each stage branch pipe are initially calculated using a biomimetic tree branching structure calculation formula. Since heat exchange is primarily achieved through external hot air, the hot air inlet is located at point 4 on the first-stage reaction branch pipe. The device has a lateral temperature gradient. To ensure full utilization of heat in each zone and catalyst performance (target conversion efficiency), the catalyst section length of each stage of the reaction branch pipe is designed accordingly. And the filling method. The gas reacting in the catalyst section passes through the cavity for flow rate regulation, pressure buffering, and ammonia preheating. The cavity length is designed. To ensure uniform gas mixing, hydrogen then passes through hydrogen selective separation membrane a and enters hydrogen separation pipeline 10.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomimetic structure based ammonia cracking hydrogen production membrane reactor, characterized in that, The application relates to a hydrogen production device, which comprises an adiabatic shell provided with a hot air inlet and a hot air outlet, and further comprises: a bionic reactor module, which comprises a main air inlet pipe, a central pipe and reaction branch pipes of various levels adopting Y-shaped fractal channel structures, the main air inlet pipe and the central pipe being arranged at two ends of the adiabatic shell respectively, The reaction branch pipe comprises several primary reaction branch pipes connected with the main air inlet pipe, each of the primary reaction branch pipes is connected with two secondary reaction branch pipes; among the two secondary reaction branch pipes connected with the same primary reaction branch pipe, one is a hydrogen separation pipe and the other is a main reaction channel; each secondary reaction branch pipe as a reaction channel is connected with two tertiary reaction branch pipes; the primary reaction branch pipe and the tertiary reaction branch pipe are main reaction channels; the bifurcation angle of each reaction branch pipe is an acute angle; catalyst carriers are arranged in the first reaction branch pipe, the second reaction branch pipe as a main reaction channel and the third reaction branch pipe, a cavity is arranged in front of a bifurcation after the catalyst carrier of each reaction branch pipe; hydrogen separation pipes are arranged at the bifurcations of the first reaction branch pipe and the second reaction branch pipe, the bifurcations of the second reaction branch pipe and the third reaction branch pipe and the ends of the third reaction branch pipe, and the inlet ends of the hydrogen separation pipes are provided with hydrogen selective separation membranes, and the outlet ends of the hydrogen separation pipes are connected with the central pipe; an exhaust pipe is further arranged at the connection between the central pipe and the adiabatic shell, and the ends of the third reaction branch pipes are connected with the exhaust pipe through pipelines; a heating module is connected with the reaction branch pipes of various levels, and the heating module is used for controllable heating of the first reaction branch pipe, the second reaction branch pipe as the main reaction channel and the third reaction branch pipe; 2. The biomimicry based ammonia cracking hydrogen production membrane reactor of claim 1, wherein, an adiabatic inner shell is further arranged in the adiabatic shell, and the central pipe is arranged in the adiabatic inner shell.

3. The biomimicry based ammonia cracking hydrogen production membrane reactor according to claim 1, wherein, The hydrogen selective separation membrane adopts a metal palladium membrane.

4. The biomimicry based ammonia cracking hydrogen production membrane reactor according to claim 1, wherein, a sensor unit is further arranged, which comprises temperature sensors, pressure sensors and hydrogen concentration sensors arranged at the branches of the reaction branch pipes of various levels.

5. The biomimicry based ammonia cracking hydrogen production membrane reactor according to claim 1, wherein, The ratio of the channel length between the first layer and the second layer and the ratio of the channel length between the second layer and the third layer are constant values, and are represented as follows: The ratio of the channel length between the first layer and the second layer and the ratio of the channel length between the second layer and the third layer are constant values, and are represented as follows: The ratio of the channel length between the first layer and the second layer and the ratio of the channel length between the second layer and the third layer are constant values, and are represented as follows: ； ； wherein indicates that each level of the channel has several branches, and each level of the reaction branch pipe .

6. The biomimicry based ammonia cracking hydrogen production membrane reactor of claim 5, wherein, The bifurcation angle The value range is .

7. The biomimicry based ammonia cracking hydrogen production membrane reactor according to claim 1, wherein, The heating module comprises resistance wires wound on the outer walls of the reaction branch pipes of various levels, and resistance wire connecting posts mounted on the adiabatic shell.

8. The biomimicry based ammonia cracking hydrogen production membrane reactor according to claim 3, wherein, The catalyst carrier in the first reaction branch pipe adopts a spherical particle packed bed form, and the catalyst carriers in the second reaction branch pipe as the main reaction channel and the third reaction branch pipe adopt honeycomb catalyst carriers. The hydrogen concentration in the cavity is measured by a hydrogen concentration sensor, and the actual hydrogen concentration generated in the front reaction zone is compared with the expected value calculated through the designed conversion rate, ； wherein, is a concentration deviation value, is the measured value of the hydrogen concentration sensor for this section, is the molar flow of the mixture of gases at the outlet of the catalyst section; is the molar flow of hydrogen. If the concentration deviation value The heating module is turned on and reheats at 70%-100% power, while the temperature sensor and pressure sensor monitor the temperature and pressure at all times and pressure If the concentration deviation value or , the heating is immediately stopped; if the concentration deviation value , the heating module operates at 0-70% power at this time; if the concentration deviation value , the heating module does not need to be started at this time; if the cavity is , the heating module is turned on to assist in heating at this time; if the cavity is , the intake air pressure needs to be increased at this time.

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