A modular plasma catalytic ammonia decomposition and hydrogen membrane separation hydrogen production device
Patent Information
- Application Number
- CN202611221192.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-12
- Publication Date
- 2026-09-15
Smart Images
Figure CN122745819A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ammonia decomposition technology, and in particular to a modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device. Background Technology
[0002] Ammonia (NH3) has a mass hydrogen storage density of 17.6%~17.8% and a volume hydrogen storage density of about 121 kgh2 / m³, which is about 71% higher than that of liquid hydrogen. It is one of the liquid hydrogen storage media with the highest known volume hydrogen storage density. The production of high-purity hydrogen by decomposing ammonia has become an important research direction in the field of hydrogen energy.
[0003] Traditional ammonia decomposition mainly employs thermocatalysis, utilizing catalysts such as Ru, Ni, and Fe to promote decomposition. However, this method suffers from problems such as high start-up temperature, high energy consumption, and easy catalyst sintering and deactivation. In recent years, dielectric barrier discharge (DBD) plasma catalysis technology has attracted widespread attention because it can generate high-energy electrons and active particles at ambient temperature and pressure, effectively reducing the activation energy of the reaction and forming a synergistic effect with the catalyst. Existing DBD plasma ammonia decomposition reactors mostly adopt a tubular structure, which basically includes a reaction tube, a high-voltage electrode, a ground electrode, a dielectric layer, and a catalyst-packed bed or a dielectric surface coating. The high-voltage electrode is usually a smooth cylindrical, rod-shaped, or wire electrode, and some devices also integrate a hydrogen-selective membrane to achieve simultaneous reaction and separation.
[0004] However, these existing technologies still have drawbacks: the high-voltage electrode surface is smooth and lacks an electric field enhancement structure, making it difficult to actively control the distribution of micro-discharge channels; the metal electrode is directly exposed to an ammonia-containing atmosphere, making it prone to corrosion and oxidation, affecting long-term operational stability; the single dielectric barrier structure has limited ability to regulate discharge current and surface charge accumulation, easily causing uneven local discharge; and the particulate catalyst packed bed not only interferes with airflow uniformity but also faces the problem of difficult replacement and maintenance. Summary of the Invention
[0005] This invention provides a modular plasma catalytic ammonia decomposition and hydrogen membrane separation hydrogen production device, which can solve the problems in the prior art, such as the limited ability of the discharge reactor to control the local electric field and micro-discharge channel, insufficient corrosion protection of the metal high-voltage electrode, and the need to improve the stability of single dielectric barrier discharge.
[0006] A modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device includes a housing. Inside the housing is a discharge reaction unit comprising a high-voltage electrode, a dielectric tube, and a grounding electrode. The high-voltage electrode includes a columnar electrode substrate and multiple conical protrusions on its outer circumferential surface. The conical protrusions are arranged axially and circumferentially along the columnar electrode substrate, with the tips of each protrusion facing the inner wall of the dielectric tube. The outer surface of the high-voltage electrode is conformally covered with a protective layer, which retains the outer contour of the tips corresponding to the conical protrusions. The dielectric tube is coaxially arranged with the high-voltage electrode, and a discharge gap is formed between the outer surface of the protective layer and the inner wall of the dielectric tube. The grounding electrode is located outside the dielectric tube. The protective layer constitutes a first dielectric barrier layer on the high-voltage electrode side, and the dielectric tube constitutes a second dielectric barrier layer on the grounding electrode side.
[0007] The present invention provides a modular plasma catalytic ammonia decomposition and hydrogen membrane separation hydrogen production device, which, compared with the prior art, has, but is not limited to, the following beneficial effects: This modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device features multiple conical protrusions arranged axially and circumferentially on the outer periphery of the columnar electrode substrate of the high-voltage electrode. The tips of each conical protrusion face the inner wall of the dielectric tube. This structure creates multiple local electric field enhancement regions distributed axially and circumferentially within the discharge gap, allowing micro-discharge channels to preferentially form between the tips of the conical protrusions and the inner wall of the dielectric tube during discharge. This actively controls the formation position and number of micro-discharge channels, effectively solving the problem of limited local electric field and micro-discharge control capabilities of existing smooth electrode structures. The outer surface of the high-voltage electrode is conformally coated with a protective layer that retains the outer contour of the conical protrusion tips. This ensures that the tip electric field enhancement effect is not weakened and completely isolates the metal high-voltage electrode from the ammonia-containing reactive gas, significantly improving the electrode's corrosion resistance and oxidation resistance, thus solving the problem of direct contact between the metal high-voltage electrode and the reactive gas. The device is susceptible to corrosion and failure when exposed to an ammonia-containing atmosphere. Simultaneously, the protective layer forms the first dielectric barrier layer on the high-voltage electrode side, and the dielectric tube forms the second dielectric barrier layer on the grounding electrode side. Together, they form a double-dielectric barrier discharge structure. The two dielectric layers effectively limit the discharge current and surface charge accumulation on both the high-voltage and grounding electrode sides, effectively suppressing excessive partial discharge and the risk of developing into a continuous arc, thus solving the problem of insufficient discharge stability in existing single-dielectric barrier structures. The electric field enhancement effect of the conical protrusion array, the conformal encapsulation and isolation protection of the protective layer, and the double-dielectric barrier structure formed by the protective layer and the dielectric tube work together to enhance discharge activity while ensuring discharge stability and protecting the electrodes from corrosion. This achieves a synergistic effect of discharge enhancement, discharge stability, and electrode protection, significantly improving the device's discharge efficiency, operational stability, and service life.
[0008] Furthermore, the inner wall of the dielectric tube is provided with a catalytically active coating, the discharge gap is not filled with loose particulate catalyst, the dielectric tube is provided with a reaction unit inlet and a reaction unit outlet communicating with the discharge gap, and the dielectric tube is provided with a reaction unit upper cover and a reaction unit lower cover.
[0009] Furthermore, it also includes a hydrogen separation unit, which is located downstream of the discharge reaction unit and is used to separate hydrogen from the mixed gas formed by ammonia decomposition. The hydrogen separation unit includes a separation unit housing and a hydrogen selective membrane disposed within the separation unit housing. The hydrogen selective membrane defines an axially intercepted gas channel, and a permeation gas collection chamber is formed between the hydrogen selective membrane and the separation unit housing. The hydrogen separation unit is provided with a separation unit inlet and an intercepted gas outlet communicating with the axially intercepted gas channel, as well as a high-purity hydrogen outlet communicating with the permeation gas collection chamber. The separation unit housing is provided with a separation unit upper cover and a separation unit lower cover.
[0010] Furthermore, there are multiple discharge reaction units and multiple hydrogen separation units, which are arranged alternately in series inside the outer shell along the direction of raw material gas flow.
[0011] Furthermore, a hydrogen collection pipe is provided on the outer shell, and the high-purity hydrogen outlet of each hydrogen separation unit is connected to the hydrogen collection pipe.
[0012] Furthermore, the discharge reaction unit and the hydrogen separation unit are connected via a quick-connect structure. This quick-connect structure includes a rotary locking ring, a conical guide, a double-layer sealing ring, an elastic electrical connector, a positioning pin, and a connecting flange. The conical guide is used for automatic alignment during axial insertion of adjacent modules. The rotary locking ring completes mechanical locking after rotating a predetermined angle. The double-layer sealing ring includes an inner ceramic seal and an outer metal O-ring, forming a double seal for the gas path. The elastic electrical connector includes a high-voltage elastic contact and a grounding elastic contact, simultaneously connecting the high-voltage line and the grounding line during the locking process of the rotary locking ring. The positioning pin restricts the circumferential position of adjacent modules, and a positioning step is provided on the connecting flange.
[0013] Furthermore, the outer casing includes a housing, one end of which is provided with an inlet flange, an inlet transition section, and a gas distributor, and the other end is provided with a gas-retaining outlet flange. A cooling jacket is provided outside the housing for regulating the operating temperature of the housing and its internal modules. The housing is also provided with a temperature detection interface, a pressure detection interface, an airtightness detection interface, and a PLC intelligent control system connection interface, which are used to monitor the temperature, pressure, sealing status of the device, and connect to an external control system, respectively.
[0014] Furthermore, the conical protrusion is a square pyramid, a triangular pyramid, a cone, a truncated cone, or a needle-like shape, and the included angle of the tip of the conical protrusion is 30°~60°. The conical protrusions in adjacent axial arrays are arranged with a circumferential offset of 45°.
[0015] Furthermore, the protective layer is prepared by 3D printing, forming layer by layer according to the outer surface contour of the high-voltage electrode.
[0016] Furthermore, the catalytically active coating is a TiO2 coating, a ZrO2 coating, a TiO2-ZrO2 composite coating, or a functional coating loaded with ammonia decomposition catalytically active components. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of a modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device according to an embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the structure of the medium-discharge reaction unit; Figure 3 for Figure 1 Schematic diagram of the hydrogen separation unit; Figure 4 for Figure 1 A schematic diagram of the quick-change connection structure.
[0018] Explanation of reference numerals in the attached figures: 1. Outer shell; 2. Discharge reaction unit; 3. Hydrogen separation unit; 4. Quick-connect structure; 11. Inlet flange; 12. Inlet transition section; 13. Gas distributor; 14. Shell; 15. High-voltage electrode interface; 16. Grounding electrode interface; 17. Temperature detection interface; 18. Pressure detection interface; 19. Air tightness detection interface; 110. PLC intelligent control system connection interface; 111. Hydrogen manifold; 112. Hydrogen main outlet; 113. Cooling jacket; 114. Support base; 115. Gas interception outlet flange; 21. Reactor unit inlet; 22. Reactor unit top cover; 23. High-voltage electrode; 24. Protective layer 25. Discharge gap; 26. Catalytic active coating; 27. Dielectric tube; 28. Grounding electrode; 29. Lower cover of reaction unit; 210. Gas outlet of reaction unit; 231. Columnar electrode substrate; 232. Conical protrusion; 31. Gas inlet of separation unit; 32. Upper cover of separation unit; 33. Gas distribution chamber; 34. Housing of separation unit; 35. Hydrogen selective membrane; 36. High-purity hydrogen outlet; 37. Permeation gas collection chamber; 38. Lower cover of separation unit; 39. Retained gas outlet; 41. Rotary locking ring; 42. Conical guide; 43. Double sealing ring; 44. Flexible electrical connector; 45. Positioning pin; 46. Connecting flange. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.
[0020] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.
[0021] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0023] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0024] Example 1: like Figure 1-2 As shown in the figure, a modular plasma catalytic ammonia decomposition and hydrogen membrane separation hydrogen production device provided by the present invention includes a shell 1, and a discharge reaction unit 2 is arranged inside the shell 1. The discharge reaction unit 2 includes a high-voltage electrode 23, a dielectric tube 27, and a grounding electrode 28. The high-voltage electrode 23 includes a columnar electrode base 231 and a plurality of conical protrusions 232 disposed on the outer peripheral surface of the columnar electrode base 231. The plurality of conical protrusions 232 are arranged along the axial and circumferential directions of the columnar electrode base 231, and the tip of each conical protrusion 232 faces the inner wall of the dielectric tube 27. The outer surface of the high-voltage electrode 23 is covered with a protective layer 24, which retains the outer contour of the tip corresponding to the conical protrusions 232. The dielectric tube 27 is coaxially arranged with the high-voltage electrode 23, and a discharge gap 25 is formed between the outer surface of the protective layer 24 and the inner wall of the dielectric tube 27. The grounding electrode 28 is disposed outside the dielectric tube 27. The protective layer 24 constitutes a first dielectric barrier layer on the side of the high-voltage electrode 23, and the dielectric tube 27 constitutes a second dielectric barrier layer on the side of the grounding electrode 28.
[0025] In this embodiment, multiple conical protrusions 232 are provided along the axial and circumferential directions on the outer peripheral surface of the columnar electrode substrate 231 of the high-voltage electrode 23. The tips of each conical protrusion 232 face the inner wall of the dielectric tube 27. This structure forms multiple local electric field enhancement regions distributed along the axial and circumferential directions within the discharge gap 25, so that during discharge, the micro-discharge channel is preferentially formed between the tip of the conical protrusion 232 and the inner wall of the dielectric tube 27, thereby actively controlling the formation position and number of micro-discharge channels, effectively solving the problem of limited local electric field and micro-discharge control capability of existing smooth electrode structures. The outer surface of the high-voltage electrode 23 is covered with a protective layer 24, and the protective layer 24 retains the outer contour of the tip of the conical protrusion 232, which not only ensures that the tip electric field enhancement effect is not weakened, but also completely isolates the metal high-voltage electrode 23 from the ammonia-containing reactive gas, significantly improving the corrosion resistance and oxidation resistance of the electrode, and solving the problem of direct exposure of existing metal high-voltage electrodes. The problem of easy corrosion and failure when exposed to an ammonia-containing atmosphere is addressed. Simultaneously, the protective layer 24 forms the first dielectric barrier layer on the high-voltage electrode 23 side, and the dielectric tube 27 forms the second dielectric barrier layer on the grounding electrode 28 side. Together, they form a double-dielectric barrier discharge structure. The two dielectric layers effectively limit the discharge current and surface charge accumulation on both the high-voltage electrode side and the grounding electrode side, effectively suppressing the risk of excessive partial discharge and the development of a continuous arc, thus solving the problem of insufficient discharge stability in existing single-dielectric barrier structures. The electric field enhancement effect of the conical protrusions 232 array, the conformal encapsulation and isolation protection of the protective layer 24, and the double-dielectric barrier structure formed by the protective layer 24 and the dielectric tube 27 work together to enhance discharge activity while ensuring discharge stability and protecting the electrodes from corrosion. This achieves a synergistic effect of discharge enhancement, discharge stability, and electrode protection, significantly improving the discharge efficiency, operational stability, and service life of the device.
[0026] Specifically, the conical protrusion 232 can be a square pyramid, a triangular pyramid, a cone, a truncated cone, or a needle-like shape. The included angle of the tip of the conical protrusion 232 is 30°~60°, and adjacent axially arrayed conical protrusions 232 are staggered by 45° in the circumferential direction. A square pyramid shape is preferred because it has the sharpest tip structure, which can generate the strongest local electric field enhancement effect under the same voltage conditions. Other shapes provide a flexible choice between electric field enhancement effect and processing cost, meeting the needs of different application scenarios. The included angle of the tip of the conical protrusion 232 is set to 30°~60°, which avoids the mechanical problems caused by an excessively small angle. The problem of insufficient strength, difficult processing, and easy tip ablation under high pressure is avoided. It also avoids the defects of excessively large included angle leading to weakened tip electric field enhancement effect and increased voltage for micro-discharge channel formation. The conical protrusions 232 of the adjacent axial array are set with a 45° circumferential offset, so that the local electric field enhancement region formed by each conical protrusion 232 in the discharge gap 25 is spatially staggered. This avoids excessive concentration of micro-discharge channels in a certain circumferential orientation, and makes the micro-discharge channels uniformly distributed in the entire circumferential and axial directions of the discharge gap 25, thereby greatly improving the uniformity of plasma spatial distribution and active particle generation efficiency in the discharge region.
[0027] The dielectric tube 27 is preferably made of quartz, but can also be replaced with high-silicon glass, borosilicate glass, alumina ceramic, glass ceramic, or other dielectric tubes that combine dielectric properties, heat resistance, and ammonia corrosion resistance. The protective layer 24 is prepared by 3D printing layer by layer according to the outer surface contour of the high-voltage electrode 23. The protective layer 24 consists of two axially extending split ceramic protective sleeves. The two split ceramic protective sleeves cover the high-voltage electrode 23 from both radial sides and are connected and sealed by an overlapping structure and a high-temperature inorganic adhesive layer. The thickness of the protective layer 24 is 0.6~0.8mm, the relative density is not less than 98%, the open porosity is not more than 2%, the room temperature dielectric strength is not less than 10 kV / mm, the volume resistivity is not less than 1×10¹² Ω·cm, and the withstand voltage of the protective layer 24 is not less than 1.5 times the maximum peak voltage it can withstand.
[0028] like Figure 1 and Figure 2 As shown, the inner wall of the dielectric tube 27 is provided with a catalytically active coating 26, the discharge gap 25 is not filled with loose particulate catalyst, the dielectric tube 27 is provided with a reaction unit inlet 21 and a reaction unit outlet 210 communicating with the discharge gap 25, and the dielectric tube 27 is provided with a reaction unit upper cover 22 and a reaction unit lower cover 29.
[0029] In this embodiment, the active intermediate generated by plasma activation of ammonia gas within the discharge gap 25 can directly undergo adsorption, dehydrogenation, and recombination reactions on the surface of the catalytic active coating 26, achieving a tight coupling between plasma discharge activation and surface catalytic reaction. This effectively reduces the activation energy and increases the ammonia decomposition reaction rate and hydrogen yield. Simultaneously, the discharge gap 25 is not filled with loose granular catalyst, completely avoiding the obstruction of gas flow by granular catalyst and the gas deviation problem caused by uneven particle accumulation. This allows the reactant gas to pass through the discharge gap 25 uniformly and smoothly, ensuring that the micro-discharge channels formed by the tips of each conical protrusion 232 are not blocked or interfered with by particles. It also eliminates potential local electric field distortions at the contact points between particles and electrodes or dielectric tubes, ensuring the uniformity and stability of the discharge. Furthermore, it avoids the problems caused by sintering, breakage, and pulverization of granular catalysts after long-term operation. The regular replacement and reactor disassembly and maintenance issues are significantly reduced, thus minimizing the difficulty of operation and maintenance and downtime. The reaction unit inlet 21 and reaction unit outlet 210, which are connected to the discharge gap 25 on the medium pipe 27, make the entry and exit paths of ammonia and reaction mixture clear and controllable, ensuring effective contact between the airflow direction and the discharge area and the surface of the catalytic coating. The upper cover 22 and the lower cover 29 of the reaction unit ensure that the discharge reaction unit 2 has good airtightness and structural integrity, allowing it to be installed, disassembled, and maintained as an independent functional module. The surface catalytic effect of the catalytic active coating 26, the smooth airflow and uniform discharge within the discharge gap 25 without particle filling, and the module independence brought by the cover structure work together to ensure that the discharge reaction unit 2 has good operational stability and convenient maintenance while maintaining high ammonia decomposition efficiency.
[0030] Specifically, the inner wall of the medium tube 27 is sequentially cleaned, roughened, and subjected to plasma surface activation treatment to form a catalytic active coating 26. The catalytic active coating 26 is a TiO2 coating, a ZrO2 coating, a TiO2-ZrO2 composite coating, or a functional coating loaded with ammonia decomposition catalytic active components.
[0031] like Figure 1 and Figure 3As shown, it also includes a hydrogen separation unit 3, which is located downstream of the discharge reaction unit 2 and is used to separate hydrogen from the mixed gas formed by ammonia decomposition. The hydrogen separation unit 3 includes a separation unit housing 34 and a hydrogen selective membrane 35 disposed within the separation unit housing 34. The hydrogen selective membrane 35 defines an axial gas interception channel, and a permeation gas collection chamber 37 is formed between the hydrogen selective membrane 35 and the separation unit housing 34. The hydrogen separation unit 3 is provided with a separation unit inlet 31 and a gas interception outlet 39 communicating with the axial gas interception channel, and a high-purity hydrogen outlet 36 communicating with the permeation gas collection chamber 37. The separation unit housing 34 is provided with a separation unit upper cover 32 and a separation unit lower cover 38, and an inlet distribution chamber 33 is formed inside the separation unit housing 34.
[0032] In this embodiment, an independent hydrogen separation unit 3 is provided downstream of the discharge reaction unit 2. The mixed gas containing hydrogen, nitrogen, and unreacted ammonia, formed after plasma catalytic decomposition of ammonia within the discharge reaction unit 2, enters the axially intercepted gas channel defined by the hydrogen selective membrane 35 through the separation unit inlet 31. Driven by the hydrogen partial pressure difference, hydrogen selectively permeates through the hydrogen selective membrane 35 into the permeation collection chamber 37 and is collected and discharged from the high-purity hydrogen outlet 36. Nitrogen and unreacted ammonia continue to flow along the axially intercepted gas channel and are discharged from the intercepted gas outlet 39, thereby achieving efficient separation of hydrogen and the reaction mixture. Furthermore, since the hydrogen separation unit 3 is independently located downstream of the discharge reaction unit 2 rather than integrated within it, the discharge reaction function and the hydrogen... The gas separation functions are structurally decoupled from each other. The discharge reaction unit 2 and the hydrogen separation unit 3 can be designed, manufactured and optimized independently. Different numbers or specifications of reaction units and separation units can be configured according to the actual processing volume and separation requirements. When the hydrogen selective membrane 35 in a certain hydrogen separation unit 3 experiences performance degradation or failure, the separation unit can be disassembled and replaced separately without stopping the system or only shutting down the corresponding module, without disassembling the discharge reaction unit 2. This greatly reduces maintenance costs and the impact on the continuous operation of the system. The upper cover 32 and the lower cover 38 of the separation unit further ensure that the hydrogen separation unit 3 itself has good airtightness and structural integrity, enabling it to be quickly installed and removed as an independent functional module, thus providing a structural basis for the multi-stage series and modular expansion of the device.
[0033] Specifically, the hydrogen selective membrane 35 is a palladium-based alloy membrane, a vanadium-based membrane with a protective layer, a niobium-based membrane, a tantalum-based membrane, a proton-conducting ceramic membrane, a silicon-based microporous membrane, a molecular sieve membrane, or a polymer-inorganic composite membrane, and its form is tubular, flat, hollow fiber, or multi-channel.
[0034] like Figure 1As shown, there are multiple discharge reaction units 2 and multiple hydrogen separation units 3, which are arranged alternately in series inside the outer shell 1 along the direction of raw material gas flow.
[0035] In this embodiment, multiple discharge reaction units 2 and multiple hydrogen separation units 3 are arranged alternately in series inside the outer casing 1 along the direction of raw material gas flow. The raw material ammonia gas flows through each stage of discharge reaction unit 2 and hydrogen separation unit 3 in sequence. The hydrogen gas generated in each stage of discharge reaction unit 2 is separated and output in a timely manner by the corresponding hydrogen separation unit 3 located downstream of it, which effectively reduces the inhibitory effect of hydrogen in the mixed gas on the ammonia decomposition reaction equilibrium, so that the ammonia decomposition equilibrium continues to shift towards the product direction, significantly improving the single-stage ammonia conversion rate and the overall raw material utilization rate. The gas trapped after separation by each stage of hydrogen separation unit 3 still contains unreacted ammonia gas, which enters along the gas flow direction. The next-stage discharge reaction unit 2 continues to participate in the plasma catalytic decomposition reaction, and then separates hydrogen again in the next-stage hydrogen separation unit 3. Through this step-by-step reaction and separation, the total ammonia conversion rate and the total hydrogen yield are significantly improved. At the same time, the discharge reaction unit 2 and the hydrogen separation unit 3 are independent and their number is adjustable, so that the discharge reaction capacity and hydrogen membrane separation capacity can be independently configured and flexibly increased or decreased according to the actual processing capacity, ammonia conversion requirements and hydrogen purity requirements. When it is necessary to increase the overall processing capacity of the device, only the corresponding number of unit modules need to be added, without redesigning the reactor structure or replacing the outer shell 1, which greatly improves the process adaptability and scalability of the device.
[0036] like Figure 1 and Figure 3 As shown, a hydrogen collection pipe 111 is provided on the outer shell 1, and the high-purity hydrogen outlet 36 of each hydrogen separation unit 3 is connected to the hydrogen collection pipe 111. The hydrogen collection pipe 111 is connected to the total hydrogen outlet 112.
[0037] In this embodiment, the high-purity hydrogen outlet 36 of each hydrogen separation unit 3 is connected to the hydrogen collection pipe 111, and the hydrogen collection pipe 111 is connected to the total hydrogen outlet 112. This allows the high-purity hydrogen separated from the mixed gas by each hydrogen separation unit 3 to flow into the hydrogen collection pipe 111 through its respective high-purity hydrogen outlet 36, and then be centrally output from the total hydrogen outlet 112, thus realizing the unified collection and management of multi-stage separated hydrogen. This collection and output structure avoids the complexity of external pipelines caused by the independent discharge of hydrogen by each hydrogen separation unit 3, reduces the number of hydrogen delivery pipelines and external interfaces, and makes the external pipeline layout of the device more compact and simple. It also reduces the problems of pipeline connection confusion, increased leakage risk, and maintenance difficulties that may occur when multiple hydrogen outlets are output separately.
[0038] like Figure 1 and Figure 4As shown, the discharge reaction unit 2 and the hydrogen separation unit 3 are connected by a quick-connect structure 4. The quick-connect structure 4 includes a rotary locking ring 41, a conical guide 42, a double-layer sealing ring 43, an elastic electrical connector 44, a positioning pin 45, and a connecting flange 46. The conical guide 42 is used for automatic alignment when adjacent modules are axially inserted. The rotary locking ring 41 completes mechanical locking after rotating at a predetermined angle. The double-layer sealing ring 43 includes an inner ceramic seal and an outer metal O-ring to form a double seal for the gas path. The elastic electrical connector 44 includes a high-voltage elastic contact and a grounding elastic contact. The connection of the high-voltage line and the grounding line is completed simultaneously during the locking process of the rotary locking ring 41. The positioning pin 45 is used to limit the circumferential position of adjacent modules. A positioning step is provided on the connecting flange 46.
[0039] In this embodiment, the tapered guide 42 achieves automatic alignment during axial insertion of adjacent modules, and the locating pin 45 restricts the circumferential position of adjacent modules. Combined with the locating step on the connecting flange 46, this ensures precise coaxiality and circumferential positioning of adjacent modules before mechanical connection. Mechanical locking is completed by rotating the locking ring 41 at a predetermined angle, eliminating the need for individual bolt tightening or special tools, significantly shortening module replacement and installation time. The double-layer sealing ring 43 includes an inner ceramic seal and an outer metal O-ring. The inner ceramic seal is high-temperature resistant, ammonia corrosion resistant, and has good airtightness. The elastic electrical connector 44 includes a high-voltage elastic contact and a grounding elastic contact, which are connected during the mechanical locking process of the rotating locking ring 41. The system completes the elastic compression connection of high-voltage lines and grounding lines in one step, eliminating the need for additional high-voltage cable plugging and unplugging, terminal tightening, or grounding clamp installation. This significantly simplifies the electrical connection process. The quick-change connection structure 4, through the coordinated operation of the automatic centering of the conical guide 42, the double sealing of the double-layer sealing ring 43, the synchronous electrical connection of the elastic electrical connector 44, and the single-step rapid locking of the rotating locking ring 41, enables the mechanical connection, air circuit sealing, and electrical connection of adjacent modules to be completed simultaneously in a single locking action. This achieves rapid plugging, accurate positioning, reliable sealing, and safe power supply of adjacent modules, significantly shortening the replacement and disassembly time of the device modules and effectively improving the device's multi-level flexible expansion capability and continuous operation and maintenance efficiency.
[0040] like Figure 1 and Figure 2As shown, the outer casing 1 includes a housing 14. One end of the housing 14 is provided with an inlet flange 11, an inlet transition section 12, and a gas distributor 13, and the other end is provided with a gas outlet flange 115. A cooling jacket 113 is provided on the outside of the housing 14 to regulate the operating temperature of the housing 14 and its internal modules. The housing 14 is also provided with a temperature detection interface 17, a pressure detection interface 18, an airtightness detection interface 19, and a PLC intelligent control system connection interface 110, which are used to monitor the temperature, pressure, sealing status of the device, and to connect to an external control system, respectively. The housing 14 is provided with a high-voltage electrode interface 15 and a grounding electrode interface 16, and a support base 114 is provided at the bottom of the housing 14.
[0041] In this embodiment, one end of the housing 14 of the outer shell 1 is provided with an inlet flange 11, an inlet transition section 12, and a gas distributor 13. The raw material ammonia gas enters the inlet transition section 12 through the inlet flange 11 and is then evenly distributed by the gas distributor 13, ensuring that the ammonia gas enters the first-stage discharge reaction unit 2 at a uniform flow rate and concentration. This avoids overloading or underloading of some discharge reaction units 2 due to uneven airflow, ensuring consistent ammonia gas processing capacity at each stage of the discharge reaction unit 2, thereby improving the overall reaction consistency and ammonia conversion efficiency of the device. The other end of the housing 14 is provided with... The gas outlet flange 115 is used to centrally discharge and transport the nitrogen, a small amount of unseparated hydrogen, and unreacted ammonia remaining after multi-stage reaction and separation to the tail gas treatment or recycling system. A cooling jacket 113 is provided outside the housing 14. By introducing a cooling medium, the operating temperature of the housing 14 and its internal multiple discharge reaction units 2 and hydrogen separation units 3 is adjusted, promptly removing the heat generated during discharge and reaction, and preventing excessively high internal temperatures from damaging the high-voltage electrode 23, protective layer 24, quartz dielectric tube 27, and catalyst. The core components, such as the selective coating 26 and the hydrogen selective membrane 35, are protected against thermal decay or damage to ensure stable operation of each functional module within a suitable temperature range. Temperature detection interface 17, pressure detection interface 18, and airtightness detection interface 19 on the housing 14 are used to monitor the internal temperature, pressure, and sealing status of the device in real time. When the detected parameters exceed the set threshold, an alarm or interlock shutdown can be initiated promptly to prevent safety accidents caused by abnormal temperature, excessive pressure, or gas leakage. The PLC intelligent control system connection interface 110 is used to connect to an external PLC control system, enabling automated control and remote monitoring of the device's operating status, improving the device's intelligent operation level and ease of operation. The high-voltage electrode interface 15 and grounding electrode interface 16 on the housing 14 are used to connect to an external high-voltage power supply and grounding line, providing a stable and reliable high-voltage power supply and grounding circuit for each discharge reaction unit 2. The support base 114 at the bottom of the housing 14 supports the entire device and ensures its structural stability and seismic performance during operation, while also facilitating installation, fixing, and transportation.
[0042] Specifically, a quadrangular pyramid array high-voltage electrode is first fabricated. Tungsten is preferably used as the electrode material. A cylindrical electrode substrate with a diameter of 5.2 mm and an effective length of 100 mm is selected. Quadrangular pyramidal protrusions are formed on the outer circumference of the cylindrical electrode substrate using laser micromachining. The base of each pyramidal protrusion is square, and the included angle at the tip is set to 30° and 60° in two embodiments. The circumferential spacing between adjacent pyramidal protrusions is 0.025 mm to reduce processing defects and stress cracking of the ceramic dielectric protective layer at the tips. Adjacent axial arrays are staggered by 45° circumferentially, causing the quadrangular pyramidal protrusions to be distributed alternately on the outer circumference of the electrode, thereby forming multiple spatially misaligned local electric field enhancement locations within the discharge region.
[0043] A ceramic dielectric protective layer 24 on the surface of the high-voltage electrode was prepared using 3D printing. Alumina ceramic slurry or powder was used as the printing material, and the layer was formed layer by layer according to the outer surface contour of the quadrangular pyramid array high-voltage electrode 23. After printing, the ceramic preform was cleaned, subjected to secondary UV curing, and dried. Degreasing was performed at a heating rate of 0.3–0.5°C / min, and the preform was held at approximately 250±20°C, 400±20°C, and 550±20°C for 1–2 hours, respectively, followed by heating to 600°C and holding for 2 hours. After degreasing, the preform was heated to 1600°C at a heating rate of 1–2°C / min and held for 2 hours to complete sintering. It was then cooled to below 800°C at a cooling rate not exceeding 3°C / min, and subsequently cooled to room temperature in the furnace.
[0044] The thickness of the sintered ceramic dielectric protective layer 24 is preferably 0.6–0.8 mm, the relative density is preferably not less than 98%, and the open porosity is preferably not more than 2%. The dielectric strength of the ceramic material at room temperature is preferably not less than 10 kV / mm, and the volume resistivity is preferably not less than 1 × 10¹² Ω·cm. The actual thickness of the ceramic dielectric protective layer 24 should be determined based on the maximum peak voltage it withstands during reactor operation, and its withstand voltage is preferably not less than 1.5 times the maximum peak voltage it withstands.
[0045] The inner wall of the dielectric tube is cleaned, dried, roughened, and subjected to plasma surface activation treatment to form a catalytically active coating 26. The treated dielectric tube, the quadrangular pyramid array high-voltage electrode 23, the ground electrode 28, the upper cover 22 of the reaction unit, and the lower cover 29 of the reaction unit are assembled to form a 1.9 mm discharge gap 25 between the outer surface of the ceramic dielectric protective layer 24 and the catalytically active coating 26, with an effective discharge length of 80 mm.
[0046] A high-voltage electrode 23, consisting of a square pyramid array covered with a ceramic dielectric protective layer 24, is installed inside the dielectric tube, creating a minimum discharge gap 25 of 1.9 mm between the outer surface of the ceramic dielectric protective layer 24 at the tip of the pyramid and the catalytically active coating 26. When the thickness of the sintered ceramic dielectric protective layer 24 is 0.6 mm, the designed inner diameter of the dielectric tube is 10.0 mm. The discharge gap at the root of the pyramid is 3.4 mm, thus creating an electric field distribution that gradually changes from the tip to the root of the pyramid within the discharge gap 25. The ceramic dielectric protective layer 24 constitutes the first dielectric barrier layer on one side of the high-voltage electrode, and the dielectric tube constitutes the second dielectric barrier layer on the other side of the ground electrode 28.
[0047] Multiple discharge reaction units 2 and multiple hydrogen separation units 3 are installed sequentially along the gas flow direction, and mechanical connections, gas path sealing, high-voltage connections, and grounding connections are completed through quick-connect structure 4. After assembly, airtightness, high-voltage continuity, grounding continuity, and insulation status are checked.
[0048] Specifically, the device in this embodiment includes three discharge reaction units 2 and three hydrogen separation units 3. The three discharge reaction units 2 and three hydrogen separation units 3 are arranged alternately along the gas flow direction, with each hydrogen separation unit 3 located downstream of the corresponding discharge reaction unit 2. Ammonia gas enters the first-stage discharge reaction unit sequentially through the inlet flange 11, the inlet transition section 12, and the gas distributor 13. Adjacent modules are connected by a quick-connect structure 4.
[0049] First, a high-voltage electrode 23 with a pyramidal array is fabricated. Tungsten is used as the electrode material. A tungsten rod blank with a diameter of 5.2 mm and a length of 100 mm is selected. The material between adjacent pyramidal protrusions is removed by five-axis laser micromachining to integrally form a cylindrical electrode substrate with a diameter of 2.0 mm and pyramidal protrusions distributed on the outer periphery of the cylindrical electrode substrate. A pyramidal array region with a length of 80 mm is set in the middle of the cylindrical electrode substrate, and smooth connecting sections with a length of 10 mm are retained at both ends. The base of the pyramidal protrusion is square, with a base length of 0.8 mm, a height of 1.50 mm, and a apex angle of 30°. The apex angle is the angle formed between two opposite sides in the longitudinal section passing through the central axis of the pyramid. Adjacent axial arrays are offset by 45° in the circumferential direction.
[0050] Two axially extending, separate ceramic dielectric protective layers were fabricated using ceramic 3D printing technology. The printing material was a ceramic slurry with alumina powder purity of no less than 99.5%, a median particle size (D50) of 0.5–1.0 μm, a solid volume fraction of 50%–60%, and a printing layer thickness of 50 μm. A three-dimensional model of the ceramic dielectric protective layer 24 was established based on the outer surface contour of the quadrangular pyramid array high-voltage electrode, and dimensional compensation was performed according to the axial and radial shrinkage rates measured from the sample.
[0051] After printing, the ceramic blank is cleaned, subjected to secondary UV curing, and dried. Degreasing is performed at a heating rate of 0.3–0.5°C / min, and the blanks are held at 250±20°C, 400±20°C, and 550±20°C for 1–2 hours, respectively, followed by heating to 600°C and holding for 2 hours. After degreasing, the blanks are heated to 1600°C at a heating rate of 1–2°C / min and held for 2 hours to complete sintering. The blanks are then cooled to below 800°C at a cooling rate not exceeding 3°C / min, and then cooled to room temperature in the furnace.
[0052] The sintered ceramic dielectric protective layer 24 has a thickness of 0.6 mm, a relative density preferably not less than 98%, an open porosity preferably not more than 2%, a room temperature dielectric strength preferably not less than 10 kV / mm, and a volume resistivity preferably not less than 1×10¹² Ω·cm. Two separate ceramic dielectric protective sleeves cover the quadrangular pyramid array high-voltage electrodes 23 from both radial sides and are connected by a stepped overlapping structure. A high-temperature alumina inorganic adhesive layer with a cured thickness of 0.05–0.15 mm is placed between the ceramic dielectric protective layer 24 and the high-voltage electrodes 23, and the overlapping positions are sealed with the same alumina inorganic adhesive.
[0053] The inner wall of the medium tube is sequentially cleaned, dried, roughened by sandblasting, and activated by plasma, and then a TiO2 catalytic active coating 26 is formed by dip coating.
[0054] A high-voltage electrode 23, consisting of a square pyramid array covered with a ceramic dielectric protective layer 24, is installed inside a dielectric tube with an effective inner diameter of 10.0 mm after the formation of the catalytically active coating 26. A minimum discharge gap 25 of 1.9 mm is formed between the outer surface of the ceramic dielectric protective layer 24 at the tip of the pyramid and the catalytically active coating 26, while the discharge gap at the root of the pyramid is approximately 3.4 mm. The ceramic dielectric protective layer 24 constitutes a first dielectric barrier layer on one side of the high-voltage electrode, and the dielectric tube constitutes a second dielectric barrier layer on the other side of the ground electrode 28, thus forming a double dielectric barrier discharge structure.
[0055] The hydrogen separation unit employs a palladium-based alloy hydrogen selective membrane 35 supported by a porous stainless steel tube. The separated hydrogen is discharged through a high-purity hydrogen outlet 36 and a hydrogen collection pipe 111, while the retained gas enters the next stage of the discharge reaction unit.
[0056] After assembly, the device was checked for airtightness, high-voltage continuity, grounding continuity, and insulation. First, nitrogen was introduced to purge the air inside the device for 30 minutes, followed by ammonia gas with a purity of at least 99.9%, at a standard flow rate of 0.30 L / min. After discharge was established, the power output was adjusted to stabilize the average discharge power of each discharge reaction unit at 30 W, resulting in a total average discharge power of 90 W for the three discharge reaction units.
[0057] In this embodiment, the ammonia conversion rate is 72%, and the hydrogen production rate is 19.44 NL / h. The hydrogen recovery rate of the three hydrogen separation units is 88%, the hydrogen purity on the permeate side is 99.98%, and the energy consumption per unit hydrogen production, calculated based on the total discharge power and the mass of hydrogen recovered on the permeate side, is approximately 58.5 kWh / kgh2.
[0058] The surface of the ceramic dielectric protective layer 24 showed no through cracks, localized breakdowns, or significant peeling. Ceramic samples prepared in the same batch and aged under the same conditions as the ceramic dielectric protective layer 24 were used for testing. Their room temperature dielectric strength was not less than 9.5 kV / mm, and their volume resistivity was not less than 8.5 × 10¹¹ Ω·cm. Specific data for each reaction stage are shown in Table 1.
[0059] Table 1 Results of NH3 passing through each stage reactor in Example 1
[0060] Example 1 employs a 30° quadrangular pyramid array high-voltage electrode and a dual dielectric barrier discharge structure. The total ammonia conversion rate after the three-stage reaction is 72.0%, and the total hydrogen production is 323.99 NmL / min, or 19.44 NL / h. The three-stage membrane separation unit cumulatively separates 285.15 NmL / min of hydrogen, with a hydrogen recovery rate of 88.0% and a hydrogen purity of 99.98% on the permeate side. After 100 hours of continuous operation, the mass loss rate of the high-voltage electrode assembly is less than 0.02%.
[0061] Example 2 The quadrangular pyramid protrusion used in this embodiment has a base length of 1.7 mm and a height of 1.50 mm, with the included angle of the tip changed to 60°. Other conditions are the same as in Embodiment 1. The specific data for each stage of reaction are shown in Table 2.
[0062] Table 2 Results of NH3 passing through each stage reactor in Example 2
[0063] Example 2 employs a 60° quadrangular pyramid array high-voltage electrode and a dual-dielectric barrier discharge structure. The total ammonia conversion rate after the three-stage reaction is 64.0%, and the total hydrogen production is 288.04 NmL / min, or 17.28 NL / h. The three-stage membrane separation unit cumulatively separates 241.92 NmL / min of hydrogen, with a hydrogen recovery rate of 84.0% and a hydrogen purity of 99.97% on the permeate side. After 100 hours of continuous operation, the mass loss rate of the high-voltage electrode assembly is less than 0.02%.
[0064] In this embodiment, the base length of the pyramidal protrusion 232 of the high-voltage electrode 23 is 1.7 mm, the height is 1.50 mm, and the tip angle is 60°. While maintaining the same electrode substrate diameter and discharge gap 25, compared to the 30° tip angle in Embodiment 1, the 60° tip angle reduces the sharpness of the tip curvature radius, thus decreasing the local electric field enhancement factor at the tip. Therefore, the single-stage ammonia conversion rates for the first, second, and third stages are 35%, 30%, and 20.9%, respectively, with a total cumulative ammonia conversion rate of 64.0%. The total hydrogen production is 288.04 NmL / min (17.28 NL / h), the hydrogen recovery rate is 84.0%, and the hydrogen purity on the permeation side is 99.97%. Although these performance indicators are slightly lower than in Embodiment 1, they still maintain a high ammonia decomposition efficiency, verifying the technical performance of this invention. The proposed solution maintains good ammonia conversion and hydrogen separation performance within a tip angle range of 30° to 60°, demonstrating broad adaptability to process parameters. The weaker electric field enhancement effect brought about by the 60° tip angle also means a reduction in the maximum electric field strength at the tip position, which reduces the electric field stress on the ceramic dielectric protective layer 24. This weakens the bombardment and thermal effects of discharge on the protective layer 24 at the tip position. After 100 hours of continuous operation, the mass loss rate of the high-voltage electrode assembly is still less than 0.02%, indicating that appropriately increasing the tip angle can further reduce the risk of tip ablation and extend the service life of the protective layer 24 while ensuring a high ammonia conversion rate. This provides a flexible parameter selection space for practical engineering applications based on different priorities of ammonia conversion efficiency and long-term operating life, further verifying the rationality of the tip angle parameter design of the quadrangular pyramidal protrusion 232 in this invention and the universality of the technical solution.
[0065] Comparative Example 1 In this comparative example, the ceramic dielectric protective layer 24 on the surface of the high-voltage electrode 23 outside the square pyramid array high-voltage electrode 23 was removed. Other conditions were the same as in Example 1. The specific data for each stage of the reaction are shown in Table 3.
[0066] Table 3. Results of NH3 passing through each stage reactor in Comparative Example 1
[0067] Comparative Example 1 uses a 30° quadrangular pyramid array high-voltage electrode, but without a ceramic dielectric protective layer on the surface of the high-voltage electrode, forming a single-dielectric barrier discharge structure. The total ammonia conversion rate after the three-stage reaction is 61.0%, and the total hydrogen production is 274.60 NmL / min, or 16.48 NL / h. The three-stage membrane separation unit cumulatively separates 225.17 NmL / min of hydrogen, with a hydrogen recovery rate of 82.0% and a hydrogen purity of 99.96% on the permeate side. After 100 hours of continuous operation, the mass loss rate of the high-voltage electrode 23, directly exposed to the ammonia-containing reaction atmosphere, is approximately 0.40%.
[0068] In this comparative example, the high-voltage electrode 23 adopts a 30° quadrangular pyramid array structure but does not have a ceramic dielectric protective layer 24 on the surface of the high-voltage electrode, forming a single dielectric barrier discharge structure. Under the same discharge power and ammonia flow rate, the total ammonia conversion rate after the three-stage reaction is 61.0%, the total hydrogen production is 274.60 NmL / min (16.48 NL / h), the hydrogen recovery rate is 82.0%, and the hydrogen purity on the permeation side is 99.96%, which are significantly higher than the 72.0% ammonia conversion rate and 1% hydrogen production rate of the double dielectric barrier discharge structure used in Example 1. The hydrogen yield of 9.44 NL / h and the hydrogen recovery rate of 88.0% both decreased significantly, indicating that although the tip of the pyramidal protrusion 232 still has a certain electric field enhancement effect after the absence of the ceramic dielectric protective layer 24, the lack of a dielectric barrier layer on the high-voltage electrode 23 side restricts the discharge current and surface charge accumulation. During the discharge process, when the local electric field is too strong, it is easy to develop into spark discharge or micro-arc, resulting in unstable discharge mode and energy dispersion. This weakens the activation efficiency of plasma for ammonia. At the same time, the exposed metal high-voltage electrode 23 is directly exposed to the ammonia-containing reaction. In the atmosphere, high-energy ions generated by the discharge continuously bombard the electrode surface. After 100 hours of continuous operation, the mass loss rate of the high-voltage electrode 23 is approximately 0.40%, which is much higher than the level of less than 0.02% of the electrode assembly mass loss rate in Example 1 due to the isolation and protection of the ceramic dielectric protective layer 24. This confirms that the electrode surface gradually deteriorates due to sputter corrosion and chemical corrosion during long-term operation, which not only shortens the electrode's service life but may also cause changes in the local electric field distribution due to changes in the electrode surface morphology, thereby affecting the discharge stability and reaction consistency. The above comparative results fully verify the indispensability of the ceramic dielectric protective layer 24 in this invention, which conformally covers the quadrangular pyramid array high-voltage electrode 23 and together with the quartz dielectric tube 27 constitutes a dual dielectric barrier discharge structure. While maintaining the electric field enhancement effect at the tip of the quadrangular pyramid protrusion 232, the protective layer 24 effectively limits the discharge current and surface charge accumulation on the high-voltage electrode 23 side, ensuring the stability of the discharge mode. It also avoids corrosion damage to the metal electrode from the ammonia-containing reaction atmosphere and ion bombardment through physical isolation. This is a key technical means to achieve efficient and stable ammonia decomposition and long-term reliable operation of the electrode.
[0069] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.
Claims
1. A modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device, characterized in that, Includes a housing (1), inside which a discharge reaction unit (2) is provided, the discharge reaction unit (2) including a high voltage electrode (23), a dielectric tube (27) and a grounding electrode (28); The high-voltage electrode (23) includes a columnar electrode base (231) and a plurality of conical protrusions (232) disposed on the outer peripheral surface of the columnar electrode base (231). The plurality of conical protrusions (232) are arranged along the axial and circumferential directions of the columnar electrode base (231), and the tip of each conical protrusion (232) faces the inner wall of the dielectric tube (27). The outer surface of the high voltage electrode (23) is covered with a protective layer (24) that conforms to the shape of the cone-shaped protrusion (232). The dielectric tube (27) is coaxially arranged with the high voltage electrode (23), and a discharge gap (25) is formed between the outer surface of the protective layer (24) and the inner wall of the dielectric tube (27). The grounding electrode (28) is arranged on the outside of the dielectric tube (27). The protective layer (24) forms the first dielectric barrier layer on the side of the high voltage electrode (23), and the dielectric tube (27) forms the second dielectric barrier layer on the side of the ground electrode (28).
2. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device as described in claim 1, characterized in that, The inner wall of the medium tube (27) is provided with a catalytic active coating (26), the discharge gap (25) is not filled with loose particulate catalyst, the medium tube (27) is provided with a reaction unit inlet (21) and a reaction unit outlet (210) communicating with the discharge gap (25), and the medium tube (27) is provided with a reaction unit upper cover (22) and a reaction unit lower cover (29).
3. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device as described in claim 1, characterized in that, It also includes a hydrogen separation unit (3), which is located downstream of the discharge reaction unit (2) and is used to separate hydrogen from the mixed gas formed by the decomposition of ammonia. The hydrogen separation unit (3) includes a separation unit housing (34) and a hydrogen selective membrane (35) disposed in the separation unit housing (34). The hydrogen selective membrane (35) defines an axial gas interception channel. A permeation gas collection chamber (37) is formed between the hydrogen selective membrane (35) and the separation unit housing (34). The hydrogen separation unit (3) is provided with a separation unit inlet (31) and a gas interception outlet (39) communicating with the axial gas interception channel, and a high-purity hydrogen outlet (36) communicating with the permeation gas collection chamber (37). The separation unit housing (34) is provided with a separation unit upper cover (32) and a separation unit lower cover (38).
4. The modular plasma catalytic ammonia decomposition and hydrogen membrane separation hydrogen production device as described in claim 3, characterized in that, There are multiple discharge reaction units (2) and hydrogen separation units (3). The multiple discharge reaction units (2) and multiple hydrogen separation units (3) are arranged in series alternately inside the shell (1) along the direction of raw material gas flow.
5. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device as described in claim 4, characterized in that, The outer shell (1) is provided with a hydrogen collection pipe (111), and the high-purity hydrogen outlet (36) of each hydrogen separation unit (3) is connected to the hydrogen collection pipe (111).
6. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device as described in claim 4, characterized in that, The discharge reaction unit (2) and the hydrogen separation unit (3) are connected by a quick-connect structure (4); The quick-connect structure (4) includes a rotary locking ring (41), a conical guide (42), a double-layer sealing ring (43), an elastic electrical connector (44), a positioning pin (45), and a connecting flange (46). The conical guide (42) is used for automatic alignment when adjacent modules are axially inserted. The rotary locking ring (41) completes mechanical locking after rotating at a predetermined angle. The double-layer sealing ring (43) includes an inner ceramic seal and an outer metal O-ring, which are used to form a double seal for the air passage. The elastic electrical connector (44) includes a high-voltage elastic contact and a grounding elastic contact. The connection of the high-voltage line and the grounding line is completed simultaneously during the locking process of the rotary locking ring (41). The positioning pin (45) is used to limit the circumferential position of adjacent modules. The connecting flange (46) is provided with a positioning step.
7. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production apparatus as described in claim 1, characterized in that, The outer casing (1) includes a housing (14). One end of the housing (14) is provided with an inlet flange (11), an inlet transition section (12) and a gas distributor (13), and the other end is provided with a gas outlet flange (115). A cooling jacket (113) is provided on the outside of the housing (14) to regulate the operating temperature of the housing (14) and its internal modules. The housing (14) is also provided with a temperature detection interface (17), a pressure detection interface (18), an airtightness detection interface (19) and a PLC intelligent control system connection interface (110), which are used to monitor the temperature, pressure, sealing status of the device and connect to the external control system, respectively.
8. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production apparatus as described in claim 1, characterized in that, The conical protrusion (232) is a square pyramid, a triangular pyramid, a cone, a truncated cone, or a needle tip. The included angle of the tip of the conical protrusion (232) is 30° to 60°. The conical protrusions (232) in adjacent axial arrays are offset by 45° in the circumferential direction.
9. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production device as described in claim 1, characterized in that, The protective layer (24) is prepared by 3D printing, forming layer by layer according to the outer surface contour of the high voltage electrode (23).
10. The modular plasma-catalyzed ammonia decomposition and hydrogen membrane separation hydrogen production apparatus as described in claim 2, characterized in that, The catalytic active coating (26) is a TiO2 coating, a ZrO2 coating, a TiO2-ZrO2 composite coating, or a functional coating loaded with ammonia decomposition catalytic active components.