A device for producing pure hydrogen by ammonia decomposition

Abstract

This invention discloses an ammonia decomposition device for producing pure hydrogen, belonging to the field of hydrogen preparation and purification technology. The device includes a vaporizer, a heat exchanger, a decomposition furnace, a dryer, a precision filter, a pressure-stabilizing buffer tank, and a multi-stage series-connected hydrogen permeation membrane separator, connected in sequence. The permeate-side outlet of the membrane separator is equipped with a non-conforming return pipeline with an online hydrogen purity analyzer and a return valve. The residual gas outlet is connected to a residual gas recycling pipeline with a tail gas buffer tank and a booster compressor. This invention uses a pressure-stabilizing buffer tank to smooth airflow fluctuations and ensure stable operation of the membrane separator; the multi-stage series-connected hydrogen permeation membrane separator achieves step-by-step sieving and purification of hydrogen, improving separation efficiency; the non-conforming purity return component ensures the qualified rate of the product hydrogen; and the residual gas recycling component pressurizes and recirculates hydrogen-rich tail gas back to the vaporizer inlet, significantly improving the overall hydrogen recovery rate of the entire process, reducing raw material consumption and tail gas emissions, and is suitable for continuous and safe production of high-purity hydrogen.

Description

Technical Field

[0001] This invention relates to the field of hydrogen preparation and purification technology, specifically to an apparatus for producing pure hydrogen by ammonia decomposition. Background Technology

[0002] Ammonia, as a highly efficient hydrogen carrier, possesses significant advantages such as high hydrogen storage density, relatively high liquefaction temperature, and mature transportation and storage infrastructure. Producing high-purity hydrogen through ammonia decomposition is one of the important technological pathways to solve the challenges of hydrogen storage and transportation and realize the large-scale application of hydrogen energy. Traditional ammonia decomposition hydrogen production processes typically include steps such as liquid ammonia vaporization, preheating, catalytic decomposition, cooling, and drying purification.

[0003] The drying process often employs a two-tower alternating adsorption drying method, which enables continuous production. However, during the regeneration and switching of the dryer, unstable switching can easily lead to fluctuations in downstream gas flow and pressure, affecting the stable operation of subsequent purification units. Furthermore, the hydrogen-rich tail gas on the permeate side is mostly directly discharged or simply burned, wasting resources and increasing the environmental burden. Therefore, we propose an ammonia decomposition device and method for producing pure hydrogen to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus for producing pure hydrogen by ammonia decomposition, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A device for producing pure hydrogen by ammonia decomposition includes a vaporizer, a heat exchanger, a decomposition furnace, a first dryer, and a second dryer. The vaporizer has an ammonia inlet on its exterior, and the outlet of the vaporizer passes through the heat exchanger, the decomposition furnace, the first dryer, and the second dryer in sequence via pipelines, and is interconnected with each component. A precision filter is installed at the junction of the outlet pipes of the first and second dryers. A pressure-stabilizing buffer tank is installed at the outlet pipe of the precision filter. A multi-stage series hydrogen permeation membrane separator, capable of progressively sieving and purifying the ammonia decomposition mixture, is installed at the outlet pipe of the pressure-stabilizing buffer tank. A high-purity hydrogen product outlet is provided at the side outlet pipe of the multi-stage series hydrogen permeation membrane separator. A purity non-compliance reflux component is also installed on the pipe between the multi-stage series hydrogen permeation membrane separator and the high-purity hydrogen product outlet. A residual tail gas recycling component is also installed between the multi-stage series hydrogen permeation membrane separator and the ammonia inlet of the vaporizer.

[0006] Preferably, the purity non-compliance reflux assembly includes an online hydrogen purity analyzer, a second reflux line, and a reflux valve; The online hydrogen purity analyzer is installed on the pipeline between the permeate side outlet of the multi-stage series hydrogen permeate membrane separator and the high-purity hydrogen product outlet. One end of the second reflux pipeline is connected to the pipeline between the high-purity hydrogen product outlet and the online hydrogen purity analyzer, and the other end is connected to the inlet pipeline of the multi-stage series hydrogen permeate membrane separator. The reflux valve is installed on the second reflux pipeline.

[0007] Preferably, the residual exhaust gas recycling assembly includes an exhaust gas buffer tank, a booster compressor, and a first return pipeline; The inlet of the tail gas buffer tank is connected to the permeate side outlet of the multi-stage series hydrogen permeation membrane separator, and the outlet of the tail gas buffer tank is connected to the inlet of the booster compressor. One end of the first reflux pipeline is connected to the outlet pipeline of the booster compressor, and the other end extends to the ammonia inlet of the vaporizer.

[0008] Preferably, the first dryer and the second dryer are arranged in parallel, and the outlet ends of the two dryers are respectively provided with a first working air outlet valve and a second working air outlet valve. The inlet pipes of the first dryer and the second dryer are respectively provided with a first regeneration air inlet valve and a second regeneration air inlet valve, which are used to switch the working state and regeneration state of the dryer.

[0009] Preferably, an ammonia inlet valve for controlling the supply of liquid ammonia is provided on the pipeline between the ammonia inlet and the vaporizer.

[0010] Preferably, the multi-stage series hydrogen permeation membrane separator is composed of multiple hydrogen permeation membrane separation units connected in series, and each separation unit is provided with an independent pipeline, with the pipeline outlet of the previous stage connected to the pipeline inlet of the next stage.

[0011] Preferably, a switching gate valve is installed in the pipeline between each of the hydrogen permeation membrane separation units; a high-purity hydrogen shut-off valve is provided at the outlet of the high-purity hydrogen product.

[0012] Preferably, a main flow pipe is also installed on the outside of the vaporizer, the inlet end of the main flow pipe is connected to the outlet end of the vaporizer, and the outlet end of the main flow pipe branches into a first branch and a second branch. The first branch is connected to the connecting pipe between the first dryer and the second dryer; the second branch is provided with an exhaust gas vent, and an exhaust valve is installed inside the second branch.

[0013] Preferably, the exhaust gas buffer tank is externally equipped with pressure monitoring instruments and liquid level monitoring instruments.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This ammonia decomposition to pure hydrogen device effectively filters out dust particles that may be entrained during the drying process by setting a precision filter and a pressure stabilizing buffer tank downstream of the dryer, and significantly suppresses airflow pressure fluctuations caused by dryer switching operations, providing a continuous, stable and clean gas source for the subsequent membrane separation unit, and ensuring the high efficiency separation performance and long-term operational stability of the membrane separator.

[0015] 2. This ammonia decomposition to pure hydrogen device, by adopting a multi-stage series hydrogen permeation membrane separator structure, can perform step-by-step, progressive screening and purification of hydrogen in the ammonia decomposition mixture. Each stage of membrane separation unit can be flexibly activated or switched according to actual working conditions, which greatly improves the flexibility and separation efficiency of hydrogen purification, while reducing the load on the single-stage membrane separator and extending the service life of the membrane module.

[0016] 3. This ammonia decomposition to pure hydrogen production device, by setting up a purity non-compliance reflux component including an online hydrogen purity analyzer, a reflux valve, and a second reflux pipeline, can monitor the purity of the product hydrogen in real time. When the purity is not up to standard, the non-compliant product gas is automatically refluxed back to the membrane separator inlet for further purification, effectively ensuring the qualification rate of the final high-purity hydrogen product and preventing non-compliant products from entering the storage tank or downstream processes. By setting up a residual tail gas recycling component including a tail gas buffer tank, a booster compressor, and a first reflux pipeline, the hydrogen-rich membrane separation residual tail gas is pressurized and recycled back to the vaporizer inlet, mixed with fresh liquid ammonia, and then re-participated in the entire hydrogen production process. This significantly improves the total hydrogen recovery rate of the entire process, reduces raw material consumption and tail gas emissions, and has significant energy-saving and environmental protection benefits. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the overall structure of the device in this invention.

[0019] In the diagram: 1. Vaporizer; 2. Heat exchanger; 3. Decomposition furnace; 4. First dryer; 5. Second dryer; 6. Precision filter; 7. Pressure stabilizing buffer tank; 8. Multi-stage series hydrogen permeation membrane separator; 9. Tail gas buffer tank; 10. Booster compressor; 11. Online hydrogen purity analyzer; 12. Ammonia inlet; 13. High-purity hydrogen product outlet; 14. Waste gas vent; 15. Ammonia inlet valve; 16. Vent valve; 171. First working outlet valve; 172. Second working outlet valve; 181. First regeneration inlet valve; 182. Second regeneration inlet valve; 19. Switching gate valve; 20. High-purity hydrogen shut-off valve; 21. Reflux valve; 22. First reflux pipeline; 23. Second reflux pipeline; 24. Mainstream pipeline. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 like Figures 1-2 As shown, this is the first embodiment of the present invention. This embodiment provides an ammonia decomposition to produce pure hydrogen device, including a vaporizer 1, a heat exchanger 2, a decomposition furnace 3, a first dryer 4, and a second dryer 5. An ammonia inlet 12 is provided on the outside of the vaporizer 1, and the outlet of the vaporizer 1 passes through the heat exchanger 2, the decomposition furnace 3, the first dryer 4, and the second dryer 5 in sequence through pipelines, and is connected to each component respectively. A precision filter 6 is installed at the junction of the outlet pipes of the first dryer 4 and the second dryer 5. A pressure stabilizing buffer tank 7 is installed at the outlet pipe of the precision filter 6. A multi-stage series hydrogen permeation membrane separator 8, which can perform step-by-step screening and purification of the ammonia decomposition mixture, is installed at the outlet pipe of the pressure stabilizing buffer tank 7. A high-purity hydrogen product outlet 13 is provided at the side outlet pipe of the multi-stage series hydrogen permeation membrane separator 8. A purity non-compliance reflux component is also installed on the pipeline between the multi-stage series hydrogen permeation membrane separator 8 and the high-purity hydrogen product outlet 13. A residual tail gas recycling component is also installed between the multi-stage series hydrogen permeation membrane separator 8 and the ammonia inlet 12 of the vaporizer 1.

[0022] It should be noted that in this embodiment, the vaporizer 1 is used to heat and vaporize liquid ammonia into gaseous ammonia, and its external ammonia inlet 12 is connected to an external liquid ammonia supply source. The heat exchanger 2 is used to recover the heat of the high-temperature decomposition gas at the outlet of the decomposition furnace 3, and to use this heat to preheat the ammonia gas before it enters the decomposition furnace 3, so as to improve energy utilization efficiency. The decomposition furnace 3 is filled with an ammonia decomposition catalyst (such as a ruthenium-based or nickel-based catalyst). Under high temperature conditions (usually 450-650°C), gaseous ammonia undergoes a catalytic decomposition reaction to generate a mixed gas containing hydrogen, nitrogen, and a small amount of unreacted ammonia and impurities. The first dryer 4 and the second dryer 5 are arranged side by side and are filled with a desiccant (such as molecular sieves, activated alumina, etc.) to adsorb and remove moisture and residual ammonia from the mixed gas, preventing them from poisoning and degrading the performance of the downstream membrane separator. The precision filter 6 preferably uses a sintered metal or polymer filter element to intercept dust particles that may fall off the dryer. The volume of the pressure stabilizing buffer tank 7 is designed according to the system's gas production capacity. Its function is to buffer pressure fluctuations caused by dryer switching or compressor start-up and shutdown, ensuring that the gas pressure entering the membrane separator remains stable within a certain range. The multi-stage series hydrogen permeation membrane separator 8 uses a palladium alloy membrane or a palladium composite membrane, utilizing the dissolution-diffusion mechanism of hydrogen on the membrane surface to achieve the separation of hydrogen from other gas components. The residual tail gas (mainly containing nitrogen, unpermeated hydrogen, and trace impurities) is pressurized by the residual tail gas recycling component and returned to the system, while the high-purity hydrogen obtained on the permeate side is output after passing the purity test by the purity failure return component.

[0023] like Figures 1-2 As shown, the purity non-compliance reflux assembly includes an online hydrogen purity analyzer 11, a second reflux line 23, and a reflux valve 21; The online hydrogen purity analyzer 11 is installed on the pipeline between the permeate side outlet of the multi-stage series hydrogen permeate membrane separator 8 and the high-purity hydrogen product outlet 13. One end of the second reflux pipeline 23 is connected to the pipeline between the high-purity hydrogen product outlet 13 and the online hydrogen purity analyzer 11, and the other end is connected to the inlet pipeline of the multi-stage series hydrogen permeate membrane separator 8. The reflux valve 21 is installed on the second reflux pipeline 23.

[0024] It should be noted that, in this embodiment, the online hydrogen purity analyzer 11 is preferably a thermal conductivity or microchromatographic hydrogen purity analyzer, which can continuously detect the hydrogen purity on the permeate side in real time. The analyzer has a built-in high-precision sensor and data processing module, and is equipped with a purity threshold setting function. When the measured purity value reaches or exceeds the set threshold, the reflux valve 21 remains closed, and high-purity hydrogen is output to the downstream storage tank or point of use through the high-purity hydrogen product outlet 13. When the measured purity value is lower than the set threshold, the control system automatically issues a command to open the reflux valve 21. At this time, the unqualified hydrogen product cannot be discharged from the high-purity hydrogen product outlet 13 (the high-purity hydrogen shut-off valve 20 can be interlocked and closed), but is guided back to the inlet pipeline of the multi-stage series hydrogen permeate membrane separator 8 through the second reflux pipeline 23, mixed with the fresh raw material gas from the pressure stabilizing buffer tank 7, and then re-enter the membrane separator for secondary purification. This cycle continues until the online hydrogen purity analyzer 11 detects that the purity is within acceptable limits. At this point, the reflux valve 21 closes, and the system resumes normal product output. This closed-loop quality control mechanism effectively prevents substandard hydrogen from entering the product storage tank, ensuring the stability and reliability of product quality.

[0025] like Figures 1-2 As shown, the residual tail gas recycling assembly includes a tail gas buffer tank 9, a booster compressor 10, and a first return pipeline 22. The inlet of the tail gas buffer tank 9 is connected to the permeate side outlet of the multi-stage series hydrogen permeation membrane separator 8, and the outlet of the tail gas buffer tank 9 is connected to the inlet of the booster compressor 10. One end of the first return pipeline 22 is connected to the outlet pipeline of the booster compressor 10, and the other end extends to the ammonia inlet 12 of the vaporizer 1.

[0026] It should be noted that in this embodiment, the exhaust gas discharged from the permeate side of the multi-stage series hydrogen permeate membrane separator 8 still contains a high concentration of hydrogen, and direct discharge would result in significant resource waste. This exhaust gas first enters the exhaust gas buffer tank 9 for temporary storage and pressure stabilization to buffer fluctuations in the outlet pressure of the membrane separator's permeate side. The outlet of the exhaust gas buffer tank 9 is connected to a booster compressor 10, which is preferably an oil-free reciprocating compressor or a diaphragm compressor. The outlet pressure is set to match the liquid ammonia supply pressure, with the specific pressure value determined based on the required mixing feed pressure at the vaporizer 1 inlet. The pressurized exhaust gas is then transported through the first return pipeline 22 to the ammonia inlet 12 of the vaporizer 1, where it merges with fresh liquid ammonia and enters the vaporizer 1 together. During this process, the residual hydrogen in the exhaust gas re-participates in the entire ammonia decomposition and purification cycle as part of the feed gas, thereby significantly improving the overall hydrogen recovery rate of the system while reducing the amount of hydrogen-containing exhaust gas discharged, thus lowering environmental risks and feed consumption.

[0027] like Figures 1-2As shown, the first dryer 4 and the second dryer 5 are arranged side by side, and the outlet ends of the two are respectively provided with a first working air outlet valve 171 and a second working air outlet valve 172. The inlet pipes of the first dryer 4 and the second dryer 5 are respectively provided with a first regeneration air inlet valve 181 and a second regeneration air inlet valve 182, which are used to switch the working state and regeneration state of the dryer.

[0028] It should be noted that in this embodiment, the first dryer 4 and the second dryer 5 are configured in parallel with redundancy to achieve continuous drying operation. During normal operation, the first working outlet valve 171 of the first dryer 4 is open, and the first regeneration inlet valve 181 is closed, allowing the raw material gas to enter the downstream after drying in the first dryer 4. Simultaneously, the second working outlet valve 172 of the second dryer 5 is closed, and the second regeneration inlet valve 182 is open, allowing high-temperature regeneration gas (usually partially heated dry gas or nitrogen) to heat and regenerate the saturated desiccant in the second dryer 5. The regeneration exhaust gas is discharged through the vent pipeline. When the desiccant in the first dryer 4 approaches saturation (which can be determined by timing or a dew point meter), the valves are switched to switch the second dryer 5 to the working state (opening the second working outlet valve 172 and closing the second regeneration inlet valve 182), while the first dryer 4 enters the regeneration state (closing the first working outlet valve 171 and opening the first regeneration inlet valve 181). This alternating switching ensures that the system can operate continuously for extended periods. The switching operation is preferably performed automatically using a programmable valve, and the switching cycle is set according to the dynamic adsorption capacity of the desiccant and the processing gas volume. The parallel arrangement structure allows the system to continue operating while one dryer is being repaired or the desiccant is being replaced, improving the overall availability of the unit.

[0029] like Figures 1-2 As shown, an ammonia inlet valve 15 for controlling the supply of liquid ammonia is installed on the pipeline between the ammonia inlet 12 and the vaporizer 1.

[0030] It should be noted that, in this embodiment, the ammonia inlet valve 15 is preferably a pneumatic or electric regulating valve, and its opening degree is controlled by the system's automatic control unit (such as a PLC or DCS). The control unit calculates the required liquid ammonia flow rate in real time using a built-in PID control algorithm based on process parameters such as the outlet temperature of the decomposition furnace 3, system pressure, and the setpoint for the product hydrogen flow rate. It then outputs a control signal to adjust the opening degree of the ammonia inlet valve 15, thereby precisely controlling the liquid ammonia supply to the vaporizer 1. This configuration ensures that the system can obtain a stable ammonia feed under different load conditions, avoiding changes in decomposition temperature and product gas composition caused by feed fluctuations. Simultaneously, the ammonia inlet valve 15 can also be interlocked with the emergency shut-off system to quickly cut off the liquid ammonia supply in the event of abnormal conditions (such as over-temperature, over-pressure, or leakage), ensuring the safety of the unit.

[0031] like Figures 1-2As shown, the multi-stage series hydrogen permeation membrane separator 8 is composed of multiple hydrogen permeation membrane separation units connected in series. Each separation unit has an independent pipeline, and the pipeline outlet of the previous stage is connected to the pipeline inlet of the next stage.

[0032] It should be noted that, in this embodiment, the multi-stage series hydrogen permeate membrane separator 8 preferably consists of 2-5 hydrogen permeate membrane separation units connected in series. Each separation unit includes an independent membrane module housing, a hydrogen permeate membrane element, a gas inlet, a permeate-side outlet, and a residual outlet. The feed gas first enters the inlet of the first-stage separation unit. Driven by the pressure difference across the membrane, hydrogen preferentially permeates through the membrane layer into the permeate side, forming hydrogen-rich permeate gas; the unpermeated residual gas is discharged from the residual outlet of this stage and enters the inlet of the next-stage separation unit for further separation. Through multi-stage series connection, each stage further extracts the residual hydrogen in the residual gas of the previous stage, so that the overall hydrogen recovery rate is progressively increased. Compared with single-stage membrane separation, the multi-stage series structure significantly improves the hydrogen separation efficiency, and the number of series stages can be flexibly selected according to the actual throughput and purity requirements, making it more adaptable.

[0033] like Figures 1-2 As shown, a switching gate valve 19 is installed in the pipeline between each hydrogen permeation membrane separation unit; a high-purity hydrogen shut-off valve 20 is installed at the high-purity hydrogen product outlet 13.

[0034] It should be noted that, in this embodiment, the switching gate valve 19 is preferably a manual or pneumatic ball valve or gate valve, installed on the connecting pipeline between two adjacent hydrogen permeation membrane separation units. When a separation unit needs to be shut down for maintenance, membrane module replacement, or malfunction, the unit can be safely isolated from the series circuit by closing the switching gate valves 19 before and after it, without affecting the normal operation of the remaining stages. This configuration significantly improves the system's operational flexibility and maintainability. The high-purity hydrogen shut-off valve 20 is installed at the high-purity hydrogen product outlet 13, preferably a pneumatic or electric shut-off valve, and is interlocked with the online hydrogen purity analyzer 11 and the reflux valve 21. When the online hydrogen purity analyzer 11 detects that the hydrogen purity is qualified, the high-purity hydrogen shut-off valve 20 automatically opens, allowing product gas output; when the purity is unqualified and the reflux valve 21 is open, the high-purity hydrogen shut-off valve 20 automatically closes to prevent unqualified gas from being output incorrectly. In addition, the high-purity hydrogen shut-off valve 20 can also be used for rapid shut-off isolation during emergency system shutdown to ensure the safety of downstream equipment.

[0035] like Figures 1-2 As shown, a main pipe 24 is also installed on the outside of the vaporizer 1. The inlet end of the main pipe 24 is connected to the outlet end of the vaporizer 1, and the outlet end of the main pipe 24 branches into the first branch and the second branch. The first branch is connected to the connecting pipe between the first dryer 4 and the second dryer 5; the second branch is provided with an exhaust gas vent 14, and an exhaust valve 16 is installed inside the second branch.

[0036] It should be noted that in this embodiment, the main pipeline 24 is used to guide the gaseous ammonia generated by the vaporizer 1 to subsequent processes in the system. The first branch serves as the normal operating path, transporting the gaseous ammonia to the heat exchanger 2 for preheating, and then into the decomposition furnace 3 for decomposition reaction. The decomposed mixed gas is cooled by the heat exchanger 2 and then enters the dryer. The second branch is an auxiliary emission path, with the exhaust vent 14 and vent valve 16 mainly used for purging emissions during the initial start-up of the unit, system depressurization during shutdown, and rapid venting in emergency situations. During normal production, the vent valve 16 remains closed; when the system needs to be shut down urgently or when unqualified gases need to be discharged, the control system opens the vent valve 16, and the gas is discharged to a safe location or flare system through the exhaust vent 14. This bypass design enhances the operational safety and flexibility of the unit, avoiding the risk of disorderly gas emissions under abnormal operating conditions.

[0037] like Figures 1-2 As shown, the exhaust gas buffer tank 9 is equipped with external pressure monitoring instruments and liquid level monitoring instruments.

[0038] It should be noted that in this embodiment, the exhaust gas buffer tank 9 serves as a temporary storage device for residual exhaust gas, and its associated pressure monitoring instruments and liquid level monitoring instruments are crucial for achieving safe and stable operation. The pressure monitoring instruments preferably employ diaphragm-type pressure transmitters or intelligent pressure sensors, installed in the gas phase space at the top of the buffer tank, for real-time monitoring of the tank's internal pressure. When the pressure exceeds the set upper limit, the control system issues an alarm and interlocks to open the vent valve for pressure relief; when the pressure falls below the set lower limit, it indicates a possible leak or insufficient flow in the system. The liquid level monitoring instruments preferably employ magnetic level gauges in conjunction with guided wave radar level transmitters, used to monitor the liquid level inside the buffer tank that may accumulate due to gas condensation or entrainment. When the liquid level reaches the set high limit, the bottom drain valve automatically opens to discharge the accumulated liquid, preventing liquid from being carried into the booster compressor 10 and causing liquid hammer damage. Both pressure and liquid level signals are transmitted remotely to the central control room, enabling remote monitoring and automatic interlocking protection, ensuring the safe and stable operation of the exhaust gas buffer tank 9 and the entire residual exhaust gas recycling assembly.

[0039] The collaborative control in this application adopts automated control methods. By using a PLC controller in conjunction with position sensors, distance sensors, temperature sensors, pressure sensors, image sensors, environmental sensors, etc., the collaborative operation of various components such as vaporizer 1, heat exchanger 2, decomposition furnace 3, first dryer 4, second dryer 5, precision filter 6, pressure stabilizing buffer tank 7, multi-stage series hydrogen permeation membrane separator 8, tail gas buffer tank 9, booster compressor 10, online hydrogen purity analyzer 11, ammonia inlet valve 15, vent valve 16, first working outlet valve 171, second working outlet valve 172, first regeneration inlet valve 181, second regeneration inlet valve 182, switching gate valve 19, high-purity hydrogen shut-off valve 20, and reflux valve 21 can be completed to achieve the above control logic. Those skilled in the art can implement it without any doubt. The connection relationship and working process of each component have been described in detail in the specification. In summary, for the ammonia decomposition pure hydrogen production device, during operation, liquid ammonia raw material enters through the ammonia inlet 12, and after the flow rate is adjusted by the ammonia inlet valve 15, it is sent into the vaporizer 1, where it is heated and vaporized into gaseous ammonia. The gaseous ammonia enters the heat exchanger 2 through the first branch of the main pipeline 24, exchanges heat with the high-temperature decomposition gas from the decomposition furnace 3 here, and after the temperature is raised to 400 - 600 °C, it enters the decomposition furnace 3. Inside the decomposition furnace 3, ammonia undergoes a decomposition reaction under the action of a catalyst to generate a mixed gas containing H2, N2, and a small amount of undecomposed ammonia. The high-temperature mixed gas returns to the heat exchanger 2, exchanges heat with the cold gaseous ammonia and is cooled to 100 - 200 °C, and then enters the first dryer 4 or the second dryer ⑤ (the working tower is determined according to the valve switching state) arranged in parallel to remove the moisture and residual ammonia in the mixed gas. The dried purified mixed gas passes through the precision filter 6 to remove the possibly entrained solid dust, and then enters the pressure stabilizing buffer tank 7 for pressure stabilization and flow buffering. The mixed gas after pressure stabilization enters the multi-stage series hydrogen permeable membrane separator 8, and hydrogen permeation separation is carried out step by step in each stage separation unit. The hydrogen-rich gas obtained on the permeation side (with a purity usually of 90% - 99.999%) is detected in real time by the on-line hydrogen purity analyzer 11. If the purity reaches the set value (such as 99.99%), the high-purity hydrogen cut-off valve 20 is opened, the reflux valve 21 is closed, and the qualified hydrogen gas is output through the high-purity hydrogen product outlet 13; if the purity is unqualified, the high-purity hydrogen cut-off valve 20 is closed, the reflux valve 21 is opened, and the unqualified hydrogen gas returns to the inlet of the multi-stage series hydrogen permeable membrane separator 8 through the second reflux pipeline 23 for re-purification. The tail gas (containing H2, N2, and trace impurities) discharged from the retentate side of the membrane separator enters the tail gas buffer tank 9 for temporary storage, and after being pressurized by the booster compressor 10, it is transported to the ammonia inlet 12 of the vaporizer 1 through the first reflux pipeline 22, mixed with fresh liquid ammonia, and then re-enters the cycle. In the entire system, the second branch of the main pipeline 24 and its vent valve 16 arranged outside the vaporizer 1 are used for abnormal condition operations such as startup purging and emergency pressure relief. The first dryer 4 and the second dryer 5 perform periodic switching between operation and regeneration through their respective working outlet valves and regeneration inlet valves to ensure continuous drying capacity. The switching gate valve 19 between each stage of the hydrogen permeable membrane separation unit realizes the on-line isolation and maintenance function of the membrane module. The pressure and liquid level monitoring instruments supporting the tail gas buffer tank 9 ensure its safe operation. Thus, the device of the present invention realizes continuous, efficient, and highly purified production of ammonia decomposition to hydrogen, and significantly improves the hydrogen recovery rate and the system operation reliability.

[0040] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An apparatus for producing pure hydrogen from ammonia by decomposition, comprising a vaporizer (1), a heat exchanger (2), a decomposition furnace (3), a first dryer (4), and a second dryer (5), characterized in that: The vaporizer (1) is provided with an ammonia inlet (12) on its exterior. The outlet of the vaporizer (1) passes through the heat exchanger (2), the decomposition furnace (3), the first dryer (4), and the second dryer (5) in sequence via pipelines, and is connected to each component respectively. A precision filter (6) is installed at the junction of the outlet pipes of the first dryer (4) and the second dryer (5). A pressure stabilizing buffer tank (7) is installed at the outlet pipe of the precision filter (6). A multi-stage series hydrogen permeation membrane separator (8) for step-by-step screening and purification of ammonia decomposition mixture is installed at the outlet pipe of the pressure stabilizing buffer tank (7). A high-purity hydrogen product outlet (13) is provided at the side outlet pipe of the multi-stage series hydrogen permeation membrane separator (8). A purity non-compliance reflux component is also provided on the pipeline between the multi-stage series hydrogen permeation membrane separator (8) and the high-purity hydrogen product outlet (13). A residual tail gas recycling component is also provided between the multi-stage series hydrogen permeation membrane separator (8) and the ammonia inlet (12) of the vaporizer (1).

2. The ammonia decomposition to pure hydrogen apparatus according to claim 1, characterized in that: The purity non-compliance reflux assembly includes an online hydrogen purity analyzer (11), a second reflux line (23), and a reflux valve (21). The online hydrogen purity analyzer (11) is installed on the pipeline between the permeate side outlet of the multi-stage series hydrogen permeate membrane separator (8) and the high-purity hydrogen product outlet (13). One end of the second reflux pipeline (23) is connected to the pipeline between the high-purity hydrogen product outlet (13) and the online hydrogen purity analyzer (11), and the other end is connected to the inlet pipeline of the multi-stage series hydrogen permeate membrane separator (8). The reflux valve (21) is installed on the second reflux pipeline (23).

3. The ammonia decomposition to pure hydrogen apparatus according to claim 2, characterized in that: The residual tail gas recycling assembly includes a tail gas buffer tank (9), a booster compressor (10), and a first return pipeline (22). The inlet of the tail gas buffer tank (9) is connected to the permeate side outlet of the multi-stage series hydrogen permeation membrane separator (8), and the outlet of the tail gas buffer tank (9) is connected to the inlet of the booster compressor (10). One end of the first reflux line (22) is connected to the outlet pipe of the booster compressor (10), and the other end extends to the ammonia inlet (12) of the vaporizer (1).

4. The ammonia decomposition to pure hydrogen apparatus according to claim 3, characterized in that: The first dryer (4) and the second dryer (5) are arranged side by side, and the outlet ends of the two are respectively provided with a first working air outlet valve (171) and a second working air outlet valve (172). The inlet pipes of the first dryer (4) and the second dryer (5) are respectively provided with a first regeneration air inlet valve (181) and a second regeneration air inlet valve (182) for switching the working state and regeneration state of the dryer.

5. The ammonia decomposition to pure hydrogen apparatus according to claim 4, characterized in that: An ammonia inlet valve (15) for controlling the supply of liquid ammonia is provided on the pipeline between the ammonia inlet (12) and the vaporizer (1).

6. The apparatus for producing pure hydrogen from ammonia decomposition according to claim 5, characterized in that: The multi-stage series hydrogen permeation membrane separator (8) is composed of multiple hydrogen permeation membrane separation units connected in series. Each separation unit has an independent pipeline, and the pipeline outlet of the previous stage is connected to the pipeline inlet of the next stage.

7. The ammonia decomposition to pure hydrogen apparatus according to claim 6, characterized in that: A switching gate valve (19) is installed in the pipeline between each of the hydrogen permeation membrane separation units; a high-purity hydrogen shut-off valve (20) is installed at the outlet (13) of the high-purity hydrogen product.

8. The ammonia decomposition to pure hydrogen apparatus according to claim 7, characterized in that: The vaporizer (1) is also equipped with a main pipe (24), the inlet end of the main pipe (24) is connected to the outlet end of the vaporizer (1), and the outlet end of the main pipe (24) branches into a first branch and a second branch. The first branch is connected to the connecting pipe between the first dryer (4) and the second dryer (5); the second branch is provided with an exhaust gas vent (14), and an exhaust valve (16) is installed inside the second branch.

9. The apparatus for producing pure hydrogen from ammonia decomposition according to claim 8, characterized in that: The exhaust gas buffer tank (9) is externally equipped with pressure monitoring instruments and liquid level monitoring instruments.

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