Ammonia decomposition hydrogen production system

Abstract

This invention specifically relates to an ammonia decomposition hydrogen production system, belonging to the field of hydrogen energy production technology, and includes: a pulsed gas inlet modulation module; a dynamic pressure shock wave reaction module; a frequency adaptive control module; a gas-solid separation and heat recovery module; and a hydrogen pressure swing adsorption purification module. In this invention, the deep coupling of the dynamic pressure shock wave and the catalytic reaction effectively enhances the entire ammonia decomposition process; the transient pressure gradient field generated by the pressure shock wave significantly promotes the desorption of nitrogen from the catalyst surface, breaking through the limitations of traditional reaction kinetics and achieving ideal reaction conversion rates under relatively mild reaction conditions; the three-dimensional network structure of the biomimetic fractal catalyst bed provides sufficient active sites for the reaction, while optimizing the gas-solid contact mode and improving mass transfer efficiency.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology, and in particular to an ammonia decomposition hydrogen production system. Background Technology

[0002] Ammonia decomposition for hydrogen production has become an important technological route in the fields of distributed hydrogen production, on-site hydrogen production, and hydrogen fuel cell supply due to its significant advantages such as high hydrogen storage density, mature storage and transportation infrastructure, and zero carbon emissions. In recent years, with the continuous advancement of catalyst materials, reactor design, and system integration technologies, ammonia decomposition for hydrogen production technology has made significant progress in reaction efficiency, stability, and economy, laying a solid foundation for the large-scale application of hydrogen energy.

[0003] In practical engineering applications, ammonia decomposition for hydrogen production still faces a series of common technical challenges that require further breakthroughs. The ammonia decomposition reaction is a strongly endothermic reaction, requiring a continuous input of large amounts of heat energy. The heat and mass transfer characteristics of traditional reactors directly affect reaction efficiency and energy consumption levels.

[0004] Meanwhile, the strong adsorption of nitrogen on the catalyst surface is the rate-controlling step of the ammonia decomposition reaction. How to effectively promote nitrogen desorption to improve the reaction conversion rate has always been a key focus and challenge in this field.

[0005] Furthermore, there is still a certain gap between the dynamic response characteristics of the existing system and the needs of rapid load fluctuations in distributed hydrogen production scenarios. Summary of the Invention

[0006] The purpose of this invention is to provide an ammonia decomposition hydrogen production system in order to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An ammonia decomposition hydrogen production system, comprising: The pulse intake modulation module is used to convert the continuous ammonia flow into a periodic pulse flow and output the initial pressure shock wave energy. The dynamic pressure shock wave reaction module receives periodic pulsed airflow and initial pressure shock wave energy, and uses the pressure shock wave to construct a dynamic flow field inside, causing ammonia to decompose into a mixed gas containing hydrogen and nitrogen under the action of a catalyst. The frequency adaptive control module dynamically adjusts the pulse frequency of the pulse intake modulation module and the resonant cavity size of the dynamic pressure shock wave reaction module by collecting the physicochemical state signals inside the dynamic pressure shock wave reaction module, thereby maintaining the standing wave resonance state. The gas-solid separation and heat recovery module receives the mixed gas, eliminates residual pressure pulsation, separates solid dust and recovers the heat energy carried by the mixed gas, and feeds the recovered heat energy back to the pulse intake modulation module for ammonia preheating, and outputs cooled clean gas. The hydrogen pressure swing adsorption purification module receives cooled clean gas and captures and releases impurity gases through periodic pressure changes, extracting and outputting high-purity hydrogen.

[0008] Preferably, the pulse air intake modulation module includes a liquid ammonia vaporization and pressure stabilization unit, a high-frequency rotating pulse generator, a nozzle acceleration unit, and a fluid rectification chamber; The liquid ammonia vaporization and pressure stabilization unit includes a vaporizer, a first-stage pressure reducing valve, and a buffer tank with a perforated flow equalization plate connected in sequence. The outlet of the buffer tank is connected to the inlet of a high-frequency rotating pulse generator, and the outlet of the high-frequency rotating pulse generator is connected to a nozzle acceleration unit.

[0009] Preferably, the high-frequency rotating pulse generator includes a stator housing, a rotating rotor coaxially mounted inside the stator housing, and a servo drive motor connected to the rotating rotor via a magnetic coupling transmission device. The rotating rotor has uniformly through-flow guide slits opened on its cylindrical surface along the circumferential direction. The nozzle acceleration unit includes a convergent section, a throat, and an expansion section connected in sequence. It is used to accelerate the pulsed airflow to a preset state to form a pressure shock wave, and to use the sound speed barrier formed by the airflow in the throat to block the pressure reflection wave generated downstream from propagating upstream.

[0010] Preferably, the dynamic pressure shock wave reaction module includes a shock wave coupling reactor shell, a biomimetic fractal catalyst bed, an acoustic resonance and reflection cavity, and a distributed heat injection unit; The shock wave coupling reactor shell is equipped with a gradually expanding inlet flange and a gradually contracting outlet flange at both ends, and the outer wall is wrapped with a composite insulation layer. The biomimetic fractal catalyst bed is set inside the shock wave coupling reactor shell, the acoustic resonance and reflection cavity is set at the tail of the shock wave coupling reactor shell, and the distributed heat injection unit includes an electric heating element embedded in the biomimetic fractal catalyst bed and high-frequency response temperature sensors distributed at different locations.

[0011] Preferably, the biomimetic fractal catalyst bed includes a porous ceramic framework with a hierarchically branched three-dimensional network structure, the surface of the porous ceramic framework is coated with a high specific surface area coating, and the high specific surface area coating is loaded with catalyst active components. The acoustic resonance and reflection cavity is equipped with an acoustic wave reflector and a ball screw mechanism that drives the acoustic wave reflector to move axially. The incident pulse pressure wave and the reflected wave generated by the acoustic wave reflector interfere with each other inside the shock wave coupling reactor shell to form a standing wave field. The region with dense catalyst loading in the biomimetic fractal catalyst bed is arranged at the antinode node of the standing wave field.

[0012] Preferably, the transient desorption rate on the surface of the biomimetic fractal catalyst bed under the action of dynamic pressure shock waves... Satisfying the formula: ; in, This represents the desorption frequency factor under standard conditions; Indicates the coverage of nitrogen atoms on the catalyst surface; This represents the intrinsic activation energy for nitrogen desorption. Represents the ideal gas constant; Indicates the absolute temperature of the catalyst surface; This represents the enhancement coefficient of the desorption process by the rate of pressure change; This represents the time derivative of the local pressure inside the shell of the shock-coupled reactor.

[0013] Preferably, the frequency adaptive control module includes a multi-dimensional signal high-speed acquisition unit, a resonance state real-time evaluation unit, an adaptive optimization execution unit, and an abnormal operating condition safety intervention unit; The multi-dimensional signal high-speed acquisition unit includes piezoelectric dynamic pressure sensors installed at equal intervals along the axial direction, armored high-frequency response thermocouples that penetrate deep into the catalyst bed, and a rapid gas analyzer based on tunable semiconductor laser absorption spectroscopy technology. These are used to acquire dynamic data and transmit it to the resonant state real-time evaluation unit. The resonant state real-time evaluation unit outputs a deviation signal to the adaptive optimization execution unit.

[0014] Preferably, the adaptive optimization execution unit calculates the target pulse frequency. Satisfying the formula: ; in, ; Indicates the harmonic order of the standing wave; Indicates the effective length of the resonant cavity; Represents the equivalent speed of sound in a gas mixture; express The equivalent specific heat ratio of the gas mixture at any given time; Represents the ideal gas constant; This represents the average absolute temperature of space. express The average molar mass of the gas mixture at any given time.

[0015] Preferably, the gas-solid separation and heat recovery module includes a pulse buffer and cyclone separation unit, a microporous ceramic fine filtration unit, a phase change heat pipe heat exchange unit, and a condensation liquefaction and gas-liquid separation unit; the pulse buffer and cyclone separation unit includes a cylindrical body with a tangential air inlet and an inverted conical ash hopper at the bottom, used to absorb residual pressure pulsations and separate large-diameter solid particles; the microporous ceramic fine filtration unit has multiple microporous ceramic filter elements with asymmetrical multilayer structures suspended in parallel inside, and is equipped with an automatic backflushing and ash removal system; the phase change heat pipe heat exchange unit has a sealing partition and a high-temperature heat pipe array passing through the sealing partition inside.

[0016] Preferably, the hydrogen pressure swing adsorption purification module includes a multi-bed programmable valve array distribution unit, a composite adsorbent bed structure unit, a pressure swing adsorption cycle timing control unit, and a tail gas buffer and energy recovery unit. The multi-bed programmable valve array distribution unit is equipped with micro-damping orifice plates and pneumatic buffer chambers at the pipeline nodes; the bottom and top of the composite adsorbent bed structure unit are equipped with biomimetic tree-shaped airflow distributors, and the interior is arranged from bottom to top as follows: an ammonia removal layer for capturing residual ammonia, a nitrogen removal layer for adsorbing nitrogen, and a purification layer for removing trace impurities. The exhaust gas buffer and energy recovery unit includes a flexible airbag buffer tank, a turbine expander, and a catalytic combustion device.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention effectively enhances the entire process of ammonia decomposition reaction through deep coupling of dynamic pressure shock waves with catalytic reactions; the transient pressure gradient field generated by the pressure shock wave can significantly promote the desorption process of nitrogen on the catalyst surface, breaking through the limitations of traditional reaction kinetics, and achieving ideal reaction conversion rate under relatively mild reaction conditions; the three-dimensional network structure of the biomimetic fractal catalyst bed provides sufficient active sites for the reaction, while optimizing the gas-solid contact mode and improving mass transfer efficiency.

[0018] 2. By arranging the catalyst loading densely at the antinodes of the standing wave field, this invention achieves a precise match between the reaction enhancement effect and the catalyst distribution, further improving the catalyst utilization efficiency. In addition, the disturbance effect of the dynamic flow field improves the temperature distribution inside the reactor, reduces the formation of local hot spots, and is conducive to the stable progress of the reaction. Attached Figure Description

[0019] Further details, features, and advantages of this application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a system structure diagram of the present invention; Figure 2 This is a flowchart of the present invention. Detailed Implementation

[0020] Several embodiments of this application will now be described in more detail with reference to the accompanying drawings to enable those skilled in the art to implement this application. This application may be embodied in many different forms and for various purposes and should not be limited to the embodiments set forth herein. These embodiments are provided to make this application thorough and complete, and to fully convey the scope of this application to those skilled in the art. The embodiments described do not limit this application.

[0021] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0022] Example 1 Its specific implementation method is combined with the appendix Figure 1 To be continued Figure 2 Please provide a detailed explanation.

[0023] Appendix Figure 1 This is a structural block diagram of an ammonia decomposition hydrogen production system provided in an embodiment of the present invention, which shows the connection relationship between the pulse gas inlet modulation module and the hydrogen pressure swing adsorption purification module, and marks the main functional interaction flow of each module.

[0024] In this embodiment, it includes: Module 1: Pulse intake modulation module, used to convert continuous ammonia gas flow into periodic pulsed gas flow and output initial pressure shock wave energy; The pulse intake modulation module is the starting point and fluid power source of the entire ammonia decomposition hydrogen production system. Its core function is to convert the continuous, steady-state ammonia gas flow upstream into a periodic pulsed gas flow with a specific frequency, amplitude, and waveform, and to provide initial pressure shock wave energy for the downstream reaction module. This module mainly consists of four sub-units: a liquid ammonia vaporization and pressure stabilization unit, a high-frequency rotating pulse generator, a nozzle acceleration unit, and a fluid rectification chamber.

[0025] The liquid ammonia vaporization and pressure stabilization unit includes a liquid ammonia storage tank, a vaporizer, a primary pressure reducing valve, a large-capacity buffer tank, and a high-precision mass flow controller.

[0026] The outlet of the liquid ammonia storage tank is connected to the inlet of the vaporizer via a high-pressure resistant stainless steel pipeline. The vaporizer adopts a water bath or electric heating structure, and is equipped with a spiral heat exchange tube bundle inside to increase the contact area between the liquid ammonia and the heat source, ensuring that the liquid ammonia can be completely converted into gaseous ammonia.

[0027] A primary pressure reducing valve is installed on the outlet pipe of the vaporizer to initially reduce the pressure of the high-pressure gaseous ammonia to the basic working pressure range set by the system.

[0028] Downstream of the primary pressure reducing valve is a large-capacity buffer tank. The buffer tank is designed to have a volume several hundred times greater than the volume of a single pulse intake, and its interior is equipped with a perforated flow equalization plate. The buffer tank's function is to eliminate low-frequency pressure fluctuations generated during the upstream vaporization process and to provide a constant-pressure gas source node for the downstream high-frequency pulse generator, preventing mechanical damage to the upstream pipeline and vaporizer caused by the reverse water hammer effect generated when the high-frequency pulse generator cuts off the airflow.

[0029] A high-precision mass flow controller is installed at the outlet of the buffer tank to accurately set and monitor the average mass flow rate of ammonia entering the downstream system.

[0030] The high-frequency rotary pulse generator is the core mechanical component for generating pulsed airflow, and it is installed downstream of the mass flow controller. The generator mainly consists of a stator housing, a rotating rotor, a servo drive motor, and a magnetic coupling transmission device.

[0031] The stator housing is made of corrosion-resistant Hastelloy material and has a high-precision cylindrical cavity machined inside. Air inlets and outlets are located on the radial sides of the stator housing, respectively. The air inlets are connected to the outlet pipe of the buffer tank, and the air outlets are connected to the downstream nozzle acceleration unit.

[0032] The rotating rotor is coaxially mounted within a cylindrical cavity of the stator housing. A very small radial clearance (typically on the micrometer level) is maintained between the outer cylindrical surface of the rotor and the inner cylindrical surface of the stator housing to achieve a non-contact gas dynamic pressure seal, reducing mechanical friction and preventing ammonia leakage. Several through-flow guide slits are uniformly formed along the circumference of the rotor's cylindrical surface. The cross-sectional shape of these guide slits is designed with a specific geometry (such as trapezoidal or teardrop shape) to control the rate of change of flow area during airflow conduction and cutoff, thereby shaping the desired pulse pressure waveform (such as a sine wave or square wave).

[0033] The servo drive motor is located outside the stator housing and is connected to the rotating rotor via a magnetic coupling transmission device. This magnetic coupling transmission device achieves dynamic-static isolation, avoiding the ammonia leakage problem that easily occurs with traditional mechanical shaft seals under high-speed rotation.

[0034] The servo drive motor rotates at a specific speed according to control commands, driving the rotor to rotate at high speed within the stator cavity. When the guide slits on the rotor rotate to coincide with the air inlet and outlet of the stator, airflow is facilitated; when the guide slits rotate to a misaligned position, the airflow is cut off. By adjusting the speed of the servo motor, the frequency of the pulsed airflow can be precisely controlled.

[0035] The nozzle acceleration unit is closely connected downstream of the outlet of the high-frequency rotating pulse generator, and it is mainly composed of a convergent-divergent nozzle (i.e., a Laval nozzle).

[0036] The nozzle has a converging inlet section, a throat in the middle, and an expanding outlet section. When the high-frequency rotating pulse generator is in the on state, high-pressure ammonia gas rushes into the nozzle instantaneously.

[0037] In the converging phase, the airflow velocity gradually increases and the pressure decreases; when the airflow reaches the throat, it reaches the preset velocity; then the airflow enters the expansion phase, the volume expands rapidly, the velocity increases further, and the pressure drops sharply.

[0038] The nozzle acceleration unit plays the following key roles here: The pressure energy of the pulsed gas flow is converted into extremely high kinetic energy, forming a pressure shock wave with a steep wavefront, which provides strong mechanical disturbance for the downstream catalytic reaction; The airflow forms a sound velocity barrier at the nozzle throat, which can effectively block the propagation of complex pressure reflection waves generated in the downstream reactor upstream, ensuring that the working state of the high-frequency rotating pulse generator is not disturbed by changes in downstream operating conditions.

[0039] To ensure that the pulse intake modulation module can stably and accurately provide the required airflow, it is necessary to perform rigorous mathematical modeling of its mass flow rate.

[0040] Instantaneous mass flow rate through the nozzle within a single pulse cycle satisfy: ; in: This represents the flow coefficient of the nozzle, which is related to the internal surface roughness of the nozzle and the viscosity of the fluid. Indicates a high-frequency rotating pulse generator in The effective flow cross-sectional area at any given time, which changes periodically with the rotation angle of the rotor; The isentropic index (specific heat ratio) of ammonia. This indicates the stagnation density of ammonia gas at the inlet of the high-frequency rotating pulse generator. This indicates the ammonia stagnation pressure at the inlet of the high-frequency rotating pulse generator.

[0041] By integrating the above formula over one pulse cycle and multiplying it by the pulse frequency, the average mass flow rate of the system can be obtained. This formula provides the basic theoretical calculation basis for the subsequent frequency adaptive control module, ensuring that the total air intake of the system remains within the set range when adjusting the pulse frequency and waveform, preventing reactor overload or reactant depletion.

[0042] Module 2: Dynamic pressure shock wave reaction module, connected to the pulse intake modulation module, receives periodic pulse airflow and initial pressure shock wave energy, and uses the pressure shock wave to construct a dynamic flow field inside, causing ammonia to decompose into a mixed gas containing hydrogen and nitrogen under the action of a catalyst.

[0043] The dynamic pressure shock wave reaction module is the core chemical reaction region of the entire system; Unlike traditional steady-state fixed-bed reactors, this module utilizes pulsed shock waves transmitted from upstream to construct highly dynamic flow, temperature, and concentration fields within the reactor. Through deep coupling of fluid dynamics and surface catalytic kinetics, it enhances the conversion efficiency of ammonia decomposition. The module primarily consists of four sub-units: a shock-coupled reactor shell, a biomimetic fractal catalyst bed, an acoustic resonance and reflection cavity, and a distributed heat injection unit.

[0044] The shock wave coupling reactor has a slender cylindrical shell and is made of high-temperature alloy materials (such as Inconel alloy) that can withstand high temperature, high pressure and high frequency alternating stress.

[0045] The length-to-diameter ratio of the shell is rigorously calculated using fluid dynamics to ensure that the pressure shock wave can form a stable propagation path inside the shell and to reduce the energy dissipation of the shock wave on the pipe wall.

[0046] The outer wall of the shell is covered with a thick composite insulation layer, which consists of aerogel insulation felt, aluminum silicate ceramic fiber blanket and stainless steel protective shell from the inside out, in order to minimize heat loss during the reaction process.

[0047] The shell has a gradually expanding inlet flange and a gradually contracting outlet flange at both ends. The gradually expanding inlet flange is connected to the upstream nozzle acceleration unit. Its internal flow channel expands in a streamlined manner, which is designed to smoothly introduce the high-speed pulse jet ejected from the nozzle into the reactor, reducing fluid separation and eddy current losses caused by abrupt changes in cross-section.

[0048] Traditional particle-packed catalyst beds generate significant fluid resistance when facing high-frequency pulsed gas flow, leading to rapid attenuation of shock wave energy and easy wear and pulverization of particles due to high-frequency vibration.

[0049] This module employs a biomimetic fractal catalyst bed, whose framework is made of high-strength porous ceramic materials such as silicon carbide or cordierite, and a three-dimensional network structure with fractal geometric features is manufactured using 3D printing technology.

[0050] This fractal structure mimics the distribution pattern of plant leaf veins or human blood vessels in nature, and has the characteristic of branching from macroscopic main channels to microscopic secondary channels.

[0051] On the surface of a porous ceramic skeleton, a high specific surface area alumina or magnesium oxide coating is uniformly loaded using coating technology, and ruthenium (Ru)-based or nickel (Ni)-based catalyst active components are highly dispersed on the coating.

[0052] When a pulsed pressure shock wave enters the biomimetic fractal catalyst bed, the shock wave propagates along the progressively branching channels. At the wavefront (high-pressure region), ammonia molecules are forcefully forced into the micropores of the catalyst coating, greatly shortening the diffusion distance of reactants to the active sites and breaking the concentration boundary layer of conventional steady-state diffusion. At the waveback (low-pressure region), an instantaneous negative pressure suction effect is generated inside the micropores.

[0053] Due to the ammonia decomposition reaction ( The reaction is a volume-increasing reaction, and the recombination and desorption of nitrogen atoms on the catalyst surface is the rate-determining step of the entire reaction. This instantaneous local low pressure can significantly reduce the desorption activation energy of nitrogen molecules, forcefully "pull" the generated nitrogen and hydrogen out of the micropores, thereby exposing fresh catalytic active sites for the next wave of ammonia molecule adsorption reaction.

[0054] To further amplify the effect of the pulsed pressure shock wave, an acoustic resonance and reflection cavity was installed at the tail end of the reactor shell (i.e., downstream of the catalyst bed).

[0055] The cavity is a cylindrical cavity with adjustable geometry, inside which is installed an axially movable sound wave reflector.

[0056] The effective length of the resonant cavity can be changed by adjusting the position of the acoustic wave reflector. When the effective length of the resonant cavity and the wavelength of the incident pulse pressure wave satisfy a specific physical relationship (such as a quarter wavelength or half wavelength), the incident wave and the reflected wave interfere inside the reactor, forming a standing wave field. The pressure amplitude reaches its maximum value at the antinode of the standing wave field.

[0057] During the system design, the region with the highest catalyst loading in the biomimetic fractal catalyst bed was precisely positioned at the antinodes of the standing wave. In this way, without increasing the energy consumption of the upstream pulse generator, the pressure pulsation amplitude can be magnified many times over in the core reaction region, further enhancing the "compression-expansion" mass transfer mechanism inside the micropores.

[0058] Ammonia decomposition is a strongly endothermic reaction. Under the strong purging of pulsed gas flow, the reaction rate increases significantly, and the heat absorption in local areas increases sharply. If the heat is not replenished in time, the temperature of the catalyst bed will drop sharply, and the reaction will stop.

[0059] The distributed heat injection unit consists of multiple independently controlled electric heating elements and high-frequency response temperature sensors. The electric heating elements are not placed outside the reactor, but are directly embedded inside the ceramic skeleton of the biomimetic fractal catalyst bed, forming an internal heating structure.

[0060] High-frequency response temperature sensors are distributed at different axial and radial positions within the bed to monitor the temperature gradient inside the bed in real time. Due to the presence of pulsed airflow, the convective heat transfer coefficient inside the bed is significantly improved. Based on the feedback from the temperature sensors, the distributed heat injection unit dynamically adjusts the output power of each group of electric heating elements to ensure sufficient heat is provided in the most intense reaction areas (such as standing wave antinodes), maintaining the entire catalyst bed within the set optimal reaction temperature range.

[0061] Under the action of dynamic pressure shock waves, the desorption rate of nitrogen atoms on the catalyst surface is no longer a constant, but is closely related to the rate of pressure change.

[0062] Corrected transient desorption rate Satisfying the formula: ; in: This represents the desorption frequency factor under standard conditions; Indicates the coverage of nitrogen atoms on the catalyst surface; This represents the intrinsic activation energy for nitrogen desorption. Represents the ideal gas constant; Indicates the absolute temperature of the catalyst surface; This represents the enhancement coefficient of the desorption process by the pressure change rate, which is related to the pore structure and surface morphology of the catalyst. The time derivative of the local pressure inside the reactor.

[0063] This formula shows that when the pressure drops sharply behind the shock wave... It is negative and has a very large absolute value (because the physical mechanism of the strengthening term in the formula is to promote desorption during decompression, in practical applications, the mathematical symbol processing of this term in the decompression stage will cause the overall desorption rate to increase exponentially or significantly. Here the formula expresses the dynamic modulation effect of the pressure derivative on the rate).

[0064] Module 3: Frequency Adaptive Control Module, which is connected to the Pulse Inlet Modulation Module and the Dynamic Pressure Shock Wave Response Module respectively. By collecting the physicochemical state signals inside the Dynamic Pressure Shock Wave Response Module, it dynamically adjusts the pulse frequency of the Pulse Inlet Modulation Module and the resonant cavity size of the Dynamic Pressure Shock Wave Response Module to maintain the standing wave resonance state. The frequency adaptive control module is the core component that ensures the dynamic pressure shock wave response module remains in a highly efficient resonant state. During the ammonia decomposition reaction, the composition of the mixed gas (the ratio of ammonia, nitrogen, and hydrogen) changes drastically as the reaction proceeds, accompanied by a strong endothermic effect that causes fluctuations in the local temperature field.

[0065] Changes in gas composition and temperature directly cause changes in the speed of sound in the gas mixture, thereby disrupting the original acoustic resonance conditions. If the pulse frequency remains constant, the standing wave field will collapse, and the amplification effect of the pressure shock wave will disappear.

[0066] Therefore, a frequency adaptive control module must be introduced to dynamically adjust the frequency of the pulse generator and the geometry of the resonant cavity by sensing the physicochemical state inside the reactor in real time. This module mainly consists of four sub-units: a multi-dimensional signal high-speed acquisition unit, a resonant state real-time evaluation unit, an adaptive optimization execution unit, and an abnormal operating condition safety intervention unit.

[0067] The multidimensional signal high-speed acquisition unit is responsible for acquiring high-frequency dynamic data of flow field, temperature field and concentration field in real time from the harsh reaction environment.

[0068] For pressure acquisition, multiple piezoelectric dynamic pressure sensors are installed at equal intervals along the axial direction of the shock wave coupled reactor shell. To prevent high temperature from damaging the piezoelectric crystals, the sensors are thermally isolated using water-cooled sleeves and fixed to the inner wall of the reactor by flush mounting, thus eliminating acoustic delay and cavity resonance interference caused by the pressure tapping tube.

[0069] These sensors are able to capture the waveform, amplitude, and time difference of the wavefront arriving at each measurement point of the pressure shock wave at an extremely high sampling rate.

[0070] For temperature acquisition, armored high-frequency response thermocouples are used, with their probes penetrating directly into the interior of the biomimetic fractal catalyst bed. The protective sheath of the thermocouple is made of an extremely thin high-temperature resistant alloy tube to reduce thermal inertia and ensure that transient temperature fluctuations generated when pulsed airflow sweeps through are accurately captured.

[0071] For concentration acquisition, a rapid gas analyzer based on Tunable Semiconductor Laser Absorption Spectroscopy (TDLAS) is installed at the reactor outlet. This analyzer emits laser light of a specific wavelength through sapphire optical windows mounted on both sides of the reactor, penetrating the gas flow field. Because ammonia molecules exhibit characteristic absorption of this specific wavelength of laser light, the instantaneous concentration of unreacted ammonia can be accurately calculated within milliseconds by analyzing the attenuation of the transmitted laser intensity, thus reflecting the real-time conversion rate of ammonia decomposition.

[0072] The massive amount of raw data acquired by the high-speed multidimensional signal acquisition unit is transmitted to the real-time resonance state evaluation unit through an anti-interference cable with a shielded layer.

[0073] At the heart of this unit is a high-speed signal processing motherboard based on a field-programmable gate array (FPGA).

[0074] First, the signal processing motherboard performs a Fast Fourier Transform (FFT) on the signal returned by the dynamic pressure sensor, converting the pressure fluctuation signal in the time domain into a frequency domain signal, and extracting the dominant frequency, harmonic components, and phase difference between various measuring points of the pressure wave inside the reactor. Then, the evaluation unit determines whether the system is in a standing wave resonance state based on the phase interference between the incident wave (generated by the upstream pulse generator) and the reflected wave (reflected by the downstream acoustic reflector) at a specific measuring point.

[0075] When the phase difference between the incident and reflected waves in the core region of the catalyst bed is close to zero (forming antinodes), it indicates that the system is in an ideal resonant state; if the phase difference shifts significantly, it indicates that the resonant state is decaying. Simultaneously, the evaluation unit also processes temperature and concentration data to provide feedforward compensation signals for subsequent frequency adjustments.

[0076] The adaptive optimization execution unit evaluates the deviation signal output by the unit in real time based on the resonance state, and dynamically corrects the system parameters through the mechanical actuator. The control objective of this unit is to keep the excitation frequency of the pulsed airflow highly consistent with the inherent acoustic resonance frequency of the reactor under the current state.

[0077] At the execution level, this unit contains two parallel adjustment paths. The first path is to adjust the upstream high-frequency rotating pulse generator.

[0078] The execution unit sends high-precision speed adjustment commands to the servo drive motor, directly adjusting the frequency of the incident pulsed airflow by changing the rotor's rotational speed. The second path involves adjusting the downstream acoustic resonance and reflection cavity. The execution unit controls a high-precision ball screw mechanism (driven by a stepper motor with an absolute encoder) connected to the acoustic reflector plate, causing the acoustic reflector plate to translate at the micrometer level along the reactor axis, thereby changing the effective physical length of the resonant cavity.

[0079] Through the coordinated action of these two pathways, the system can quickly re-establish and lock the standing wave resonance field when the gas composition and temperature change drastically, ensuring that the "compression-expansion" mass transfer mechanism inside the catalyst micropores is always in the most efficient operating range.

[0080] To achieve precise adaptive control, a core computational model based on gas dynamics is embedded within the adaptive optimization execution unit.

[0081] During the decomposition of ammonia, the equivalent speed of sound of the mixed gas... It changes dynamically with time and space, and satisfies: ; in: express The equivalent specific heat ratio of the gas mixture at any given time; Represents the ideal gas constant; This indicates the spatial average absolute temperature of the catalyst bed inside the reactor; express The average molar mass of the gas mixture at any given time.

[0082] Due to the ammonia decomposition reaction ( This process converts large ammonia molecules into smaller nitrogen and hydrogen molecules. As the conversion rate increases, the average molar mass of the mixed gas also increases. It will decrease significantly.

[0083] According to the above formula, a decrease in molar mass will lead to a decrease in the velocity of sound in the gas mixture. A significant increase.

[0084] To maintain standing wave resonance, the system requires a target pulse frequency. The resonance condition formula must be satisfied: ; in: The harmonic order of the standing wave is indicated (usually taken as a positive integer). This indicates the effective length of the resonant cavity, determined by the position of the sound wave reflector.

[0085] The adaptive optimization execution unit is based on the two core formulas mentioned above, combined with real-time collected temperature and concentration data (used to calculate molar mass), to continuously calculate the target frequency and drive the servo motor and stepper motor to eliminate the deviation between the actual frequency and the target frequency.

[0086] Under the intense disturbance of dynamic pressure shock waves, the system faces the potential risk of local pressure exceeding limits or temperature runaway.

[0087] The abnormal operating condition safety intervention unit is independent of the conventional optimization control logic and has the highest control priority. When the dynamic pressure sensor detects that the pressure peak inside the reactor exceeds the set safety threshold, or the thermocouple detects an abnormal local temperature rise rate, this unit will immediately trigger a hardware-level interrupt response.

[0088] Its intervention measures include: instantly cutting off the power supply to the servo motor of the high-frequency rotating pulse generator, causing the rotor to stop due to inertia or to be rapidly braked by an electromagnetic brake, thereby cutting off the pulse shock wave source; simultaneously, opening the fast pressure relief valves installed on the buffer tank and reactor shell to safely discharge the high-pressure gas inside the system to the exhaust gas treatment main pipe. This independent safety intervention mechanism ensures the mechanical integrity and operational safety of the system under extreme operating conditions.

[0089] Module 4: Gas-solid separation and heat recovery module, connected to the exhaust end of dynamic pressure shock wave reaction module, receives mixed gas, eliminates residual pressure pulsation, separates solid dust and recovers the heat energy carried by the mixed gas, feeds the recovered heat energy back to pulse intake modulation module for ammonia preheating, and outputs cooled clean gas.

[0090] The mixed gas discharged from the dynamic pressure shock wave reaction module (containing generated hydrogen, nitrogen and a small amount of unreacted ammonia) is not only at a high temperature, but also inevitably carries trace amounts of catalyst powder or tiny solid particles detached from the ceramic skeleton due to the strong mechanical scouring of the high-frequency pulsed airflow.

[0091] Furthermore, the discharged gas still carries residual pressure pulsation energy. The core function of the gas-solid separation and heat recovery module is to efficiently recover the high-grade sensible heat carried by the mixed gas while eliminating residual pulsation and purifying the gas. This heat can be used to preheat upstream liquid ammonia or as a heat source for other processes, thereby significantly improving the thermodynamic efficiency of the entire system. This module mainly consists of four sub-units: a pulse buffer and cyclone separation unit, a microporous ceramic fine filtration unit, a phase change heat pipe heat exchange unit, and a condensation liquefaction and gas-liquid separation unit.

[0092] This unit is the first processing stage after the high-temperature mixed gas leaves the reactor. Its main structure is a specially designed expansion cyclone separator.

[0093] The separator has a cylindrical upper section and an inverted conical ash hopper at the bottom. High-temperature mixed gas with residual pressure pulsations enters the cylindrical section at high speed through a tangential inlet. Because the internal volume of the cylinder is much larger than the exhaust pipe cross-section of the reactor, the gas expands upon entering the cylinder. The residual pressure pulsation energy is significantly attenuated and absorbed during this process, achieving a smooth transition from a pulsating state to a steady state, thus acting as a pneumatic buffer. Simultaneously, the tangentially entering airflow forms a high-speed rotating external vortex on the inner wall of the cylinder. Under the action of strong centrifugal force, larger catalyst particles (typically above the micrometer scale) and ceramic dust entrained in the gas are thrown towards the inner wall of the cylinder. After losing kinetic energy, they slide down the inner wall under gravity to the inverted conical ash hopper at the bottom for centralized collection.

[0094] The purified gas forms an internal vortex at the center of the cylinder and is discharged upwards through the central exhaust pipe. This unit achieves preliminary gas-solid separation while effectively protecting downstream, more sophisticated filtration and heat exchange equipment from wear and blockage caused by large particles.

[0095] Even after cyclone separation, the gas may still contain submicron-sized ultrafine dust particles. If these dust particles enter downstream heat exchangers or purification components, they can cause severe surface scaling and pore blockage.

[0096] The gas then enters a microporous ceramic fine filtration unit for deep purification. This unit contains multiple tubular microporous ceramic filter elements suspended in parallel within its housing. These filter elements are made from silicon carbide or high-purity alumina powder sintered at high temperatures, and have an asymmetric multi-layered structure: an inner layer with large pores providing mechanical strength; and an outer layer with extremely small pores for intercepting ultrafine dust.

[0097] High-temperature gas permeates from the outside to the inside of the ceramic filter tube, and ultrafine dust is trapped on the outer surface of the ceramic tube, forming an extremely thin filter cake layer, while clean gas enters the internal channel of the ceramic tube and is collected and discharged.

[0098] To maintain long-term low-resistance operation of the filter element, this unit is equipped with an automatic backflushing cleaning system. When the pressure difference across the filter element reaches a set value, the system briefly opens the backflushing solenoid valve, using a small stream of high-pressure clean gas to perform an instantaneous pulse backflushing from the inside of the ceramic tube to the outside, shaking the filter cake layer attached to the outer surface into the dust collection hopper at the bottom, thereby restoring the filtration performance of the ceramic tube.

[0099] The high-temperature clean mixed gas, after deep purification, enters the phase change heat pipe heat exchange unit for heat recovery. Unlike traditional shell-and-tube or plate heat exchangers, this unit uses an array of high-temperature heat pipes as heat transfer elements.

[0100] A heat pipe is a passive heat transfer element with extremely high thermal conductivity. Its interior is evacuated and filled with an appropriate amount of liquid working fluid (such as heat transfer oil or liquid sodium / potassium metal, selected according to the specific temperature range).

[0101] The heat pipe's inner wall is sintered with a capillary wick structure made of metal wire mesh or porous powder. The heat exchange unit's shell is divided into a hot fluid channel and a cold fluid channel by a central sealing partition. The heat pipe array passes through the sealing partition, with one end located in the hot fluid channel (evaporation section) and the other end in the cold fluid channel (condensation section). When the high-temperature mixed gas flows through the evaporation section of the heat pipe, it transfers heat to the heat pipe wall. The liquid working fluid inside the pipe absorbs heat and rapidly boils and vaporizes. Driven by a small pressure difference, the vapor flows at high speed to the condensation section located in the cold fluid channel. Upon encountering the cold fluid flowing through this section (such as preheated liquid ammonia or cooling water), it releases its latent heat and recondenses into a liquid. The condensed liquid then flows back to the evaporation section by the capillary suction force of the capillary wick or gravity, completing a closed thermodynamic cycle.

[0102] The significant advantage of using a phase change heat pipe heat exchange unit is that the hot fluid and cold fluid are physically isolated by a sealed partition and the heat pipe wall. Even if a single heat pipe is damaged, it will not cause cross-leakage between the high-temperature hydrogen-containing gas mixture and the cold fluid, thus eliminating safety hazards. Meanwhile, the isothermal heat transfer characteristics of the heat pipe ensure a uniform temperature distribution on the heat exchanger surface, effectively avoiding condensation corrosion caused by localized cold spots.

[0103] Although most pressure pulsations are eliminated in the buffer unit, weak low-frequency velocity pulsations remain in the airflow entering the heat exchange unit. These residual pulsations can disrupt the flow and thermal boundary layers on the heat exchange tube surfaces, thereby enhancing convective heat transfer. Convective heat transfer coefficient under pulsating airflow. satisfy: ; in: It represents the convective heat transfer coefficient for steady-state flow under the same average flow velocity; This represents the empirical enhancement factor related to the geometric arrangement of the heat exchanger tube bundle; Indicates the amplitude of residual airflow velocity fluctuations; The angular frequency representing the residual airflow fluctuations; This represents the average velocity of the airflow passing through the heat exchanger tube bundle.

[0104] This formula reveals the physical mechanism by which residual pulsating kinetic energy is converted into heat energy.

[0105] By rationally designing the volume of the buffer unit and deliberately retaining residual pulsations of specific amplitude and frequency, the overall heat transfer coefficient of the phase change heat pipe heat exchange unit can be significantly improved without increasing additional power consumption, thereby reducing the volume and material cost of the heat exchanger.

[0106] After the mixed gas is significantly cooled by the phase change heat pipe heat exchange unit, it enters the condensation and liquefaction and gas-liquid separation unit for final temperature regulation and phase separation.

[0107] This unit mainly consists of a deep cooler and a high-efficiency gas-liquid separator. The deep cooler uses circulating cooling water or forced air cooling as the cold source to further reduce the temperature of the mixed gas to near ambient temperature. At this temperature, the unreacted residual ammonia in the mixed gas (if the system is operating at a higher base pressure) will reach its saturated vapor pressure, thus undergoing a phase change and condensing from a gaseous state into liquid ammonia droplets.

[0108] The gas-liquid mixture enters a high-efficiency gas-liquid separator, which is equipped with baffles and a wire mesh demister. The airflow changes direction multiple times as it passes through the baffles. Larger droplets impact the baffles due to inertia and converge and flow down. Tiny droplets entrained in the airflow are intercepted by the dense metal wire mesh and agglomerate into larger droplets as they pass through the wire mesh demister. Finally, under the influence of gravity, they drip into the collection tank at the bottom of the separator.

[0109] The collected liquid ammonia can be recycled back into the upstream liquid ammonia storage tank via a reflux pump. The gas after gas-liquid separation (mainly composed of high-purity hydrogen and nitrogen, and trace amounts of gaseous ammonia) is discharged from the top of the separation tank and sent to the downstream purification module.

[0110] Module 5: Hydrogen Pressure Swing Adsorption Purification Module, connected to the gas-solid separation and heat recovery module, receives the cooled clean gas, captures and releases impurity gases through periodic pressure changes, and extracts and outputs high-purity hydrogen. Although the gas processed by the front-end gas-solid separation and heat recovery module has removed solid dust and liquid ammonia droplets, its main components are still hydrogen, nitrogen, and trace amounts of gaseous ammonia. To meet the stringent requirements for high-purity hydrogen in advanced applications such as fuel cells, this gas mixture must undergo deep separation.

[0111] The hydrogen pressure swing adsorption purification module utilizes the difference in adsorption affinity of different gas molecules on the surface of a solid adsorbent to capture and release impurity gases through periodic pressure changes, thereby extracting high-purity hydrogen.

[0112] This module mainly consists of five sub-units: a multi-bed programmable valve array distribution unit, a composite adsorbent bed structure unit, a pressure swing adsorption cycle timing control unit, a tail gas buffer and energy recovery unit, and a multi-component competitive adsorption kinetic model.

[0113] The multi-bed programmable valve array distribution unit is the physical hub for controlling complex airflow directions. To ensure a continuous and stable output of hydrogen products, this system typically employs a pressure swing adsorption (PSA) architecture with four or six towers connected in parallel.

[0114] This unit consists of a dense piping network and numerous high-frequency response programmable pneumatic valves. The piping network uses seamless 316L stainless steel pipes with electrochemically polished inner and outer surfaces to minimize gas flow resistance and the adsorption of trace impurities by the pipe walls. The programmable pneumatic valves are angle seat valves or pneumatic diaphragm regulating valves with extremely low leakage rates and ultra-long service lives. Each adsorption tower is equipped with an inlet valve, a product gas outlet valve, a reverse pressure relief valve, a forward pressure relief valve, a multiple pressure equalization valve, and a flushing gas valve at its bottom and top. To eliminate the water hammer effect and pressure surges caused by valve switching, the unit incorporates miniature damping orifice plates and pneumatic buffer chambers at key piping nodes.

[0115] When the control system issues a valve switching command, the pneumatic actuator completes the valve core displacement within milliseconds, precisely guiding the raw material gas, product gas, equalizing gas, and desorption tail gas to flow between different adsorption towers according to the set sequence. Furthermore, all valves are equipped with valve position feedback sensors to monitor the actual opening and closing status of the valves in real time, preventing gas crossflow and purity degradation caused by valve jamming.

[0116] The composite adsorbent bed structure unit is the core physicochemical region for achieving highly selective gas separation. Each adsorption tower is an upright cylindrical pressure vessel, filled with a composite adsorbent bed carefully designed for different impurity gases.

[0117] To prevent channeling (airflow concentrated in local channels) or wall flow (airflow rapidly short-circuiting along the tower wall) in adsorption towers with large diameters, biomimetic tree-shaped airflow distributors are installed at the bottom and top of the adsorption towers.

[0118] The distributor uses multi-branched guide vanes to evenly distribute the concentrated airflow across the entire bed cross-section, ensuring full contact between the gas and the adsorbent.

[0119] The adsorbent bed adopts a multi-level composite filling technology, which is divided into an ammonia removal layer, a nitrogen removal layer and a purification layer from bottom to top: bottom layer (ammonia removal layer): filled with silica gel that has been surface acid modified or activated carbon impregnated with specific metal salts.

[0120] Ammonia molecules have strong polarity. This layer of adsorbent utilizes its abundant hydroxyl or acidic sites on its surface to powerfully capture trace amounts of residual ammonia through hydrogen bonding and chemical coordination, preventing ammonia from entering the upper layer and causing poisoning and failure of the advanced adsorbent.

[0121] Middle layer (denitrification layer): Filled with high-performance 5A or 13X zeolite molecular sieves. Although nitrogen molecules are nonpolar molecules, they have a large quadrupole moment. The regular micropores and strong electrostatic gradient inside the zeolite molecular sieve can generate strong induced dipole interactions with the quadrupole moment of nitrogen molecules, thus preferentially and massively adsorbing nitrogen molecules in the presence of hydrogen (which has extremely low polarizability and no quadrupole moment).

[0122] Top layer (refining layer): Filled with special carbon molecular sieves or high-silica zeolite with extremely narrow pore size distribution. This layer is mainly used to remove trace impurities that may leak from the first two layers (such as trace amounts of methane, carbon monoxide, etc., if the upstream liquid ammonia feedstock contains such impurities), ensuring that the final output hydrogen purity reaches fuel cell grade standards of over 99.999%.

[0123] The pressure swing adsorption (PSA) cycle timing control unit is the "brain" of the entire purification module. Through a programmable logic controller (PLC), it strictly directs the actions of the multi-bed programmable valve array distribution unit according to a preset timing logic. A complete PSA cycle includes the following processes: Adsorption Step: High-pressure mixed gas enters from the bottom of the column and passes sequentially through the composite adsorbent bed. Ammonia and nitrogen are retained by the adsorbent, while high-purity hydrogen flows out from the top of the column and is sent to the product gas buffer tank. As adsorption proceeds, the mass transfer zone within the bed gradually moves upward. When the leading edge of the mass transfer zone is about to reach the top of the column, the gas intake is stopped, and the adsorption step ends.

[0124] Multiple pressure equalization and depressurization steps: After adsorption is completed, a large amount of high-pressure, high-purity hydrogen gas still remains in the dead volume inside the tower.

[0125] To recover this portion of the hydrogen, the column is connected to other columns operating at lower pressures. High-pressure gas flows from this column to the low-pressure columns, achieving pressure equalization. Typically, two to three consecutive pressure equalization operations are performed to maximize hydrogen recovery.

[0126] Forward depressurization step: After pressure equalization, the pressure inside the column is further reduced. At this time, some gas is released from the top of the column in the original gas flow direction. Although this gas contains some impurities, it still has a high hydrogen concentration and is collected for rinsing other adsorption columns that are in the desorption state.

[0127] Reverse pressure release step: After the forward pressure release is completed, open the reverse pressure release valve at the bottom of the tower, and the pressure inside the tower will rapidly drop to near atmospheric pressure. With the sudden drop in pressure, a large amount of nitrogen and ammonia adsorbed on the surface of the adsorbent will desorb and be discharged from the bottom of the tower against the original gas flow direction, entering the tail gas buffer tank.

[0128] Washing and desorption steps: In order to thoroughly remove the impurities remaining in the micropores of the adsorbent, high-purity gas generated by the forward depressurization of other towers is introduced from the top of the tower and the bed is washed in reverse under low pressure to remove the residual impurities from the tower and restore the adsorbent's adsorption capacity.

[0129] Multiple pressure equalization and final pressure increase steps: After desorption is completed, the tower receives pressure equalization gas from other high-pressure towers in sequence for initial pressure increase, and finally uses high-purity hydrogen in the product gas buffer tank for final pressure increase until the working pressure required for the adsorption step is reached, ready for the next cycle.

[0130] The exhaust gas discharged during the reverse depressurization and flushing desorption steps (mainly composed of nitrogen, desorbed ammonia, and a small amount of unrecovered hydrogen) exhibits certain pressure fluctuations. The exhaust gas buffer and energy recovery unit first receives these exhaust gases through a large-volume flexible airbag buffer tank, eliminating pressure pulsations and transforming them into a stable, continuous airflow.

[0131] Since the exhaust gas still contains a certain amount of pressure energy, a miniature turboexpander is installed downstream of the buffer tank in this unit. The smooth exhaust gas flow drives the turboexpander impeller to rotate at high speed, converting the pressure energy of the gas into mechanical energy, which in turn drives the coaxially connected generator to generate electricity.

[0132] The generated electricity, after being inverted and rectified, is fed into the system's internal power grid to drive the high-frequency rotating pulse generator or distributed heat injection unit at the front end, thereby significantly reducing the overall energy consumption of the entire hydrogen production system. The low-pressure tail gas after expansion and depressurization is then sent to the catalytic combustion unit, where residual hydrogen and ammonia are used for flameless catalytic combustion. The heat generated is returned to the system for preheating the vaporization of liquid ammonia.

[0133] To accurately design the dimensions of the adsorption tower and optimize the circulation sequence, mathematical modeling of the complex mass transfer process within the composite adsorbent bed is essential. Under conditions of a multi-component gas mixture (hydrogen, nitrogen, and ammonia), the adsorption capacity of each component on the adsorbent surface depends not only on its own physical properties but also is strongly influenced by the competitive adsorption of other components. equilibrium adsorption capacity Satisfying the core formula of the extended Langmuir-Freundlich multicomponent competitive adsorption isotherm: ; in: Indicates components The amount of saturated monolayer adsorption on this adsorbent is related to the specific surface area and micropore volume of the adsorbent. Indicates components The adsorption affinity constant reflects the strength of the interaction between gas molecules and the surface of the adsorbent, and its value decreases exponentially with increasing temperature. Indicates components Partial pressure in the gas phase; Indicates components The heterogeneity parameter is used to correct the non-uniformity of energy distribution on the adsorbent surface; This indicates the total number of components in the gas mixture (mainly hydrogen, nitrogen, and ammonia in this system); the summation term in the denominator. It rigorously expresses the mutual exclusion and competition effects of different gas molecules on a limited number of adsorption sites.

[0134] In practical engineering applications, the PLC of the pressure swing adsorption cycle timing control unit incorporates a numerical solution algorithm based on this formula. By collecting inlet pressure, temperature, and component concentration in real time, the system can dynamically calculate the movement speed of the mass transfer zone within the bed, thereby adaptively adjusting the duration of the adsorption step. This prevents impurities from penetrating and causing hydrogen purity to be substandard, while also avoiding a decrease in hydrogen recovery rate due to excessively short adsorption time, thus achieving intelligent and efficient purification.

[0135] Example 2 This embodiment provides an integrated, miniaturized, self-heating, cascaded hydrogen production system utilizing ammonia decomposition with a rated hydrogen production capacity of 5 Nm³ / h. The specific structure and implementation method are as follows: System core components: Liquid ammonia storage unit: includes a 10L liquid ammonia storage tank, a high-precision electromagnetic flow control valve, and a rated working pressure of 1.0MPa.

[0136] Electric auxiliary start-up unit: includes a 2kW electrically heated liquid ammonia vaporizer and a 3kW electric auxiliary catalytic burner; the electric auxiliary catalytic burner has a built-in honeycomb ceramic carrier, on which a Pt-CeO2 / Al2O3 low-temperature combustion catalyst is coated, with a Pt loading of 0.5wt%, a CeO2 doping amount of 10wt%, and a catalyst ignition temperature of 175℃.

[0137] Integrated microchannel coupled reaction unit: Made of 310S stainless steel in one piece, with external dimensions of 300mm×200mm×150mm. The interior is set with alternating layers of ammonia decomposition catalytic channels and catalytic combustion channels. The width of a single channel is 1mm and the wall thickness between channels is 0.3mm, with a total of 20 layers of decomposition channels and 20 layers of combustion channels. The inner wall of the decomposition channel is coated with Ru-La2O3 / Al2O3 ammonia decomposition catalyst, with Ru loading of 2wt% and La2O3 doping of 8wt%. The inner wall of the combustion channel is coated with the same low-temperature combustion catalyst as the electric catalytic burner.

[0138] The four-stage waste heat recovery unit includes a first-stage decomposition gas-premixed gas plate heat exchanger, a second-stage flue gas-raw material ammonia tube heat exchanger, a third-stage flue gas-liquid ammonia vaporization shell and tube heat exchanger, and a fourth-stage tail gas-air preheating finned heat exchanger. All heat exchangers are made of 316L stainless steel, and the heat exchange area is matched to the system heat load.

[0139] Adaptive control unit: It adopts a PLC controller and is equipped with 8 temperature sensors, 4 pressure sensors, and 6 electromagnetic flow regulating valves, with a built-in three-stage adaptive control program.

[0140] Ammonia purification unit: Employs a palladium membrane purification device connected to the decomposition gas outlet, outputting hydrogen with a purity ≥99.999%.

[0141] System operation process: During the cold start phase, the adaptive control unit activates the electric heating modules of the electrically heated liquid ammonia vaporizer and the electric auxiliary catalytic burner. Liquid ammonia from the storage tank is vaporized by electric heating and then mixed with air supplied by the blower at an ammonia-to-air ratio of 1:5. This mixture enters the electric auxiliary catalytic burner, where the heating wire heats the mixture to above 180°C, igniting the catalyst. The resulting high-temperature flue gas enters the combustion channel of the integrated microchannel coupled reaction unit, rapidly heating the reactor. During this phase, the total electric heating power is 5kW, and the reactor temperature rises from room temperature to 600°C in ≤12 minutes. During the transition operation phase, when the reactor core temperature reaches 600℃, the adaptive control unit gradually switches the gas path: the feed path of the ammonia gas for combustion is switched from the electrically heated gasifier to the three-stage flue gas-liquid ammonia gasifier. The mixture of ammonia gas and air for combustion is first passed into the first-stage decomposition gas-premixed gas heat exchanger for preheating. At the same time, the feed of raw ammonia gas is gradually turned on. After the gasified ammonia gas is preheated by the second-stage flue gas-raw material ammonia heat exchanger, it enters the decomposition channel of the reactor for ammonia decomposition reaction. The high-temperature hydrogen-nitrogen mixture generated by decomposition enters the first-stage heat exchanger to provide heat for the combustion premixed gas. During this phase, the electric heating power of the electric auxiliary catalytic burner is gradually reduced until it is completely shut down. During the switching process, the reactor temperature fluctuation is ≤±15℃, and the ammonia decomposition rate is always ≥99.9%.

[0142] During the self-heating steady-state operation phase, when the reactor temperature stabilizes at 590-610℃ and the preheating temperature of the raw ammonia gas reaches above 460℃, the adaptive control unit completely shuts down all electric heating modules of the electrically heated liquid ammonia vaporizer and the electrically assisted catalytic burner, and the system enters fully self-heating steady-state operation. Liquid ammonia is completely vaporized through a three-stage flue gas-liquid ammonia vaporizer. The vaporized ammonia is divided into two streams: one stream is raw material ammonia (accounting for 85%), and the other stream is combustion ammonia (accounting for 15%). The raw ammonia is preheated to 460°C in a secondary flue gas-raw ammonia heat exchanger and then enters the reactor decomposition channel, where it undergoes ammonia decomposition at 600°C with a decomposition rate of ≥99.95%. The resulting 590°C high-temperature hydrogen-nitrogen mixed gas enters a primary decomposition gas-premixed gas heat exchanger, where the combustion premixed gas is preheated to 320°C. The heat-exchanged hydrogen-nitrogen mixed gas then enters a palladium membrane purification unit to obtain high-purity hydrogen. Ammonia is mixed with air preheated by a four-stage tail gas-air preheater at an ammonia-air ratio of 1:4.5. After being preheated to 320°C by a first-stage heat exchanger, the mixture enters the reactor combustion channel for catalytic combustion with a combustion efficiency of ≥99.5%. The generated 600°C high-temperature heat is directly transferred to the decomposition channel through the channel wall, providing all the heat required for the ammonia decomposition reaction. The 540°C high-temperature flue gas produced after combustion enters the secondary flue gas-raw material ammonia heat exchanger to provide heat for preheating the raw material ammonia. The flue gas, cooled to 200°C, enters the tertiary flue gas-liquid ammonia vaporizer to provide all the heat for liquid ammonia vaporization. The tail gas, further cooled to 80°C, enters the quaternary tail gas-air preheater to preheat the combustion air. Finally, the tail gas is discharged into the atmosphere. X Emissions ≤8ppm; During this stage, the system consumes no additional electricity, with only the fan consuming ≤100W. The system's thermal efficiency is ≥93%, and it can stably maintain self-heating balance within the 30%-100% rated load range. The ammonia decomposition rate is always ≥99.95%.

[0143] Example 3 This embodiment provides a skid-mounted integrated autothermal ammonia decomposition hydrogen production system with a rated hydrogen production capacity of 20 Nm³ / h. The overall skid dimensions are 1200 mm × 800 mm × 1000 mm, and the volume is ≤1 m³. 3 It adopts the same system structure and control logic as Example 1, only with the reactor size, heat exchanger heat exchange area and catalyst loading amount scaled up; the system cold start time is ≤15 minutes, the ammonia decomposition rate under self-heating steady state is ≥99.98%, and the system thermal utilization rate is ≥92%, which can be directly applied to distributed hydrogen refueling stations, small hydrogen supply stations in industrial parks and other scenarios.

[0144] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An ammonia decomposition hydrogen production system, characterized in that, include: The pulse intake modulation module is used to convert the continuous ammonia flow into a periodic pulse flow and output the initial pressure shock wave energy. The dynamic pressure shock wave reaction module receives periodic pulsed airflow and initial pressure shock wave energy, and uses the pressure shock wave to construct a dynamic flow field inside, causing ammonia to decompose into a mixed gas containing hydrogen and nitrogen under the action of a catalyst. The frequency adaptive control module dynamically adjusts the pulse frequency of the pulse intake modulation module and the resonant cavity size of the dynamic pressure shock wave reaction module by collecting the physicochemical state signals inside the dynamic pressure shock wave reaction module, thereby maintaining the standing wave resonance state. The gas-solid separation and heat recovery module receives the mixed gas, eliminates residual pressure pulsation, separates solid dust and recovers the heat energy carried by the mixed gas, and feeds the recovered heat energy back to the pulse intake modulation module for ammonia preheating, and outputs cooled clean gas. The hydrogen pressure swing adsorption purification module receives cooled clean gas and captures and releases impurity gases through periodic pressure changes, extracting and outputting high-purity hydrogen.

2. The ammonia decomposition hydrogen production system according to claim 1, characterized in that, The pulse intake modulation module includes a liquid ammonia vaporization and pressure stabilization unit, a high-frequency rotating pulse generator, a nozzle acceleration unit, and a fluid rectification chamber; The liquid ammonia vaporization and pressure stabilization unit includes a vaporizer, a first-stage pressure reducing valve, and a buffer tank with a perforated flow equalization plate connected in sequence. The outlet of the buffer tank is connected to the inlet of a high-frequency rotating pulse generator, and the outlet of the high-frequency rotating pulse generator is connected to a nozzle acceleration unit.

3. The ammonia decomposition hydrogen production system according to claim 2, characterized in that, The high-frequency rotating pulse generator includes a stator housing, a rotating rotor coaxially mounted inside the stator housing, and a servo drive motor connected to the rotating rotor via a magnetic coupling transmission device. The rotating rotor has uniformly through-flow guide slits opened on its cylindrical surface along the circumferential direction. The nozzle acceleration unit includes a convergent section, a throat, and an expansion section connected in sequence. It is used to accelerate the pulsed airflow to a preset state to form a pressure shock wave, and to use the sound speed barrier formed by the airflow in the throat to block the pressure reflection wave generated downstream from propagating upstream.

4. The ammonia decomposition hydrogen production system according to claim 1, characterized in that, The dynamic pressure shock wave reaction module includes a shock wave coupled reactor shell, a biomimetic fractal catalyst bed, an acoustic resonance and reflection cavity, and a distributed heat injection unit; The shock wave coupling reactor shell is equipped with a gradually expanding inlet flange and a gradually contracting outlet flange at both ends, and the outer wall is wrapped with a composite insulation layer. The biomimetic fractal catalyst bed is set inside the shock wave coupling reactor shell, the acoustic resonance and reflection cavity is set at the tail of the shock wave coupling reactor shell, and the distributed heat injection unit includes an electric heating element embedded in the biomimetic fractal catalyst bed and high-frequency response temperature sensors distributed at different locations.

5. The ammonia decomposition hydrogen production system according to claim 4, characterized in that, The biomimetic fractal catalyst bed includes a porous ceramic framework with a hierarchically branched three-dimensional network structure, the surface of which is coated with a high specific surface area coating, and the catalyst active components are loaded on the high specific surface area coating. The acoustic resonance and reflection cavity is equipped with an acoustic wave reflector and a ball screw mechanism that drives the acoustic wave reflector to move axially. The incident pulse pressure wave and the reflected wave generated by the acoustic wave reflector interfere with each other inside the shock wave coupling reactor shell to form a standing wave field. The region with dense catalyst loading in the biomimetic fractal catalyst bed is arranged at the antinode node of the standing wave field.

6. The ammonia decomposition hydrogen production system according to claim 5, characterized in that, The transient desorption rate on the surface of the biomimetic fractal catalyst bed under the action of dynamic pressure shock waves. Satisfying the formula: ; in, This represents the desorption frequency factor under standard conditions; Indicates the coverage of nitrogen atoms on the catalyst surface; This represents the intrinsic activation energy for nitrogen desorption. Represents the ideal gas constant; Indicates the absolute temperature of the catalyst surface; This represents the enhancement coefficient of the desorption process by the rate of pressure change; This represents the time derivative of the local pressure inside the shell of the shock-coupled reactor.

7. The ammonia decomposition hydrogen production system according to claim 1, characterized in that, The frequency adaptive control module includes a multi-dimensional signal high-speed acquisition unit, a resonance state real-time evaluation unit, an adaptive optimization execution unit, and an abnormal operating condition safety intervention unit; The multi-dimensional signal high-speed acquisition unit includes piezoelectric dynamic pressure sensors installed at equal intervals along the axial direction, armored high-frequency response thermocouples that penetrate deep into the catalyst bed, and a rapid gas analyzer based on tunable semiconductor laser absorption spectroscopy technology. These are used to acquire dynamic data and transmit it to the resonant state real-time evaluation unit. The resonant state real-time evaluation unit outputs a deviation signal to the adaptive optimization execution unit.

8. The ammonia decomposition hydrogen production system according to claim 7, characterized in that, The adaptive optimization execution unit calculates the target pulse frequency. Satisfying the formula: ; in, ; Indicates the harmonic order of the standing wave; Indicates the effective length of the resonant cavity; Represents the equivalent speed of sound in a gas mixture; express The equivalent specific heat ratio of the gas mixture at any given time; Represents the ideal gas constant; This represents the average absolute temperature of space. express The average molar mass of the gas mixture at any given time.

9. The ammonia decomposition hydrogen production system according to claim 1, characterized in that, The gas-solid separation and heat recovery module includes a pulse buffer and cyclone separation unit, a microporous ceramic fine filtration unit, a phase change heat pipe heat exchange unit, and a condensation and liquefaction and gas-liquid separation unit. The pulse buffer and cyclone separation unit includes a cylindrical body with a tangential air inlet and an inverted conical ash hopper at the bottom, used to absorb residual pressure pulsations and separate large-diameter solid particles. The microporous ceramic fine filtration unit has multiple microporous ceramic filter elements with asymmetrical multilayer structures suspended in parallel inside, and is equipped with an automatic backflushing and ash removal system. The phase change heat pipe heat exchange unit has a sealing partition and a high-temperature heat pipe array passing through the sealing partition.

10. The ammonia decomposition hydrogen production system according to claim 1, characterized in that, The hydrogen pressure swing adsorption purification module includes a multi-bed programmable valve array distribution unit, a composite adsorbent bed structure unit, a pressure swing adsorption cycle timing control unit, and a tail gas buffer and energy recovery unit. The multi-bed programmable valve array distribution unit is equipped with micro-damping orifice plates and pneumatic buffer chambers at the pipeline nodes; the bottom and top of the composite adsorbent bed structure unit are equipped with biomimetic tree-shaped airflow distributors, and the interior is arranged from bottom to top as follows: an ammonia removal layer for capturing residual ammonia, a nitrogen removal layer for adsorbing nitrogen, and a purification layer for removing trace impurities. The exhaust gas buffer and energy recovery unit includes a flexible airbag buffer tank, a turbine expander, and a catalytic combustion device.

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