Hydrogen production device by corona discharge and hydrogen production method thereof

Abstract

The present application relates to a kind of hydrogen production device of corona discharge and its hydrogen production method, including high voltage electrode, ground electrode, spiral pipe, along gas flow direction, spiral pipe includes activation section, reaction section and output section, activation section has first pitch and first curvature radius;Reaction section is located downstream of activation section and is connected therewith, and the reaction section has second pitch and second curvature radius;Output section is located downstream of reaction section and is connected therewith, and the output section is used to export hydrogen-rich product;First pitch < second pitch, and first curvature radius ≤ second curvature radius.The present application adopts the sectional flow channel structure of multistage gradient variable pitch, variable curvature radius or same curvature radius, combined with the reaction interval of fine division, can be differentiated regulation and control flow field form and disturbance intensity according to gas reaction process difference.Effectively solve the industry pain points that traditional equipment generally exists, such as insufficient activation of front-end raw material, uneven distribution of middle section cracking reaction, back-end gas flow retention and accumulation, discharge working condition fluctuation and instability.

Description

Technical Field

[0001] This invention relates to the field of plasma hydrogen production technology, specifically to a corona discharge hydrogen production device and its hydrogen production method. Background Technology

[0002] Plasma technology, as a highly efficient and clean method for activating molecules, has shown great potential in hydrogen production (such as methane reforming, steam reforming, and methanol-to-hydrogen). Its core advantage lies in its ability to directly break chemical bonds using high-energy electrons under relatively mild conditions, thus avoiding the high-temperature and high-pressure environment required by traditional thermocatalytic processes. It features rapid start-up and shutdown, and a compact process, making it suitable for distributed and small-scale hydrogen production scenarios. Currently, based on different plasma generation methods, the mainstream technical routes mainly include arc discharge, dielectric barrier discharge, microwave discharge, and corona discharge. Arc discharge plasma has high density but is a thermal plasma with extremely high gas temperatures, resulting in significant energy loss as heat, high energy consumption, and stringent requirements for the heat resistance of electrode materials and reactors. Corona discharge, as a typical low-temperature non-equilibrium plasma, has a gas temperature close to room temperature, with energy mainly concentrated in the generation of high-energy electrons, making its energy utilization path more economical.

[0003] Authorization Announcement No.: CN116425115B, Application Date: March 15, 2023, Invention Title: An Apparatus for Hydrogen Production by Arc Plasma Cracking. This apparatus includes, from top to bottom, a gas-tight arc plasma torch, a cracking chamber assembly, and a heat exchange chamber assembly connected sequentially. The gas-tight arc plasma torch includes electrodes, a compensating ceramic, a torch bottom cover, an insulating ceramic, a torch connecting piece, a torch outer shell, and two ionized air inlet pipes. The electrodes are arranged along a central axis, and the torch bottom cover is fitted over the electrodes. A compensating ceramic is located above the torch bottom cover, and an insulating ceramic is located below it. The bottom of the insulating ceramic is fixed to the torch outer shell via the torch connecting piece. Two ionized air inlet pipes are formed tangentially on the torch outer shell, and the pair of ionized air inlet pipes are arranged in parallel. This invention generates arc plasma through the gas-tight arc plasma torch, which is ejected from the central hole of the torch connecting piece and enters the cracking chamber. Air preheated in the outer cavity of the pyrolysis chamber and fuel preheated and vaporized in the coils inside the heat exchange chamber enter the inner cavity of the pyrolysis chamber tangentially. After being fully mixed, they come into full contact with the plasma injected into the inner cavity of the pyrolysis chamber, completing the pyrolysis and generating hydrogen.

[0004] The aforementioned existing technology uses high-temperature arc discharge, which has disadvantages such as poor discharge stability, extremely high gas temperature leading to a large amount of energy being lost in the form of heat, severe electrode ablation, low raw material pyrolysis conversion rate, insufficient reaction mixing, and many by-products. Summary of the Invention

[0005] In view of the inherent defects of existing electric arc plasma hydrogen production technology, such as high operating energy consumption, low feedstock pyrolysis conversion rate, and insufficient reaction mixing, this invention aims to provide a corona discharge hydrogen production device and method that can gradient control the flow field morphology and fluid disturbance intensity, optimize the plasma reaction environment, and significantly improve the feedstock activation pyrolysis efficiency and hydrogen production conversion rate.

[0006] The technical solution provided by this invention is as follows: A corona discharge hydrogen production device includes a high-voltage electrode and a grounding electrode, and also includes a helical tube along the gas flow direction, the helical tube comprising, An activation segment, wherein the activation segment has a first pitch and a first radius of curvature; A reaction section, located downstream of and connected to the activation section, the reaction section having a second pitch and a second radius of curvature; An output section, located downstream of and connected to the reaction section, is used to produce hydrogen-rich products. Wherein, the first pitch is less than the second pitch, and the first radius of curvature is less than or equal to the second radius of curvature.

[0007] Furthermore, the output section adopts a straight tube structure or a spiral tube structure; When the output section is a helical tube structure, the output section has a third pitch and a third radius of curvature; wherein, the second pitch is less than the third pitch, and the second radius of curvature is less than or equal to the third radius of curvature.

[0008] Furthermore, along the gas flow direction, the reaction section sequentially includes a front transition section, a main reaction section, and a rear transition section; the front transition section is connected to the activation section, and the rear transition section is connected to the output section; The second pitch includes the front pitch of the corresponding front transition section, the main reaction section pitch of the corresponding main reaction section, and the rear pitch of the corresponding rear transition section, wherein the front pitch ≤ the main reaction section pitch ≤ the rear pitch.

[0009] Furthermore, the inner diameter of the spiral tube is 4~30mm; along the central axis of the spiral tube's spiral profile, the axial length of the front transition section and the rear transition section is 5~30mm.

[0010] Furthermore, the high-voltage electrodes are continuously arranged along the central axis of the spiral tube, and the minimum net distance between the high-voltage electrodes and the inner wall of the spiral tube is 2mm to 20mm.

[0011] Furthermore, the high-voltage electrode is a solid metal electrode, and the cross-sectional dimensions of the high-voltage electrode gradually decrease along the gas flow direction, so as to make the electric field strength of the activation section greater than that of the reaction section.

[0012] Furthermore, the grounding electrode is a metal layer covering the outer wall of the spiral tube.

[0013] Furthermore, the ratio of the first pitch of the activated section to the inner diameter of the spiral tube is in the range of 1.5 to 4; The ratio of the second pitch of the reaction section to the inner diameter of the spiral tube is in the range of 4 to 10.

[0014] When the output section is a helical tube structure, the ratio of the third pitch of the output section to the inner diameter of the helical tube is greater than 10.

[0015] Furthermore, on a radial section perpendicular to the central axis of the spiral tube's spiral profile, the sections of the activation section and the reaction section are concentric circles. The ratio of the first radius of curvature of the activated section to the inner diameter of the helical tube is in the range of 0.5 to 3. The ratio of the second radius of curvature of the reaction section to the inner diameter of the helical tube is in the range of 3 to 8. When the output section is a helical tube structure, the ratio of the third radius of curvature of the output section to the inner diameter of the helical tube is in the range of 8 to 13.

[0016] Furthermore, along the central axis of the spiral tube's spiral profile, the axial length of the reaction section is 2 to 8 times the axial length of the activation section.

[0017] Furthermore, the spiral tube is made of insulating material, and its wall thickness is uniformly set, with a value of 1mm to 5mm.

[0018] A method for producing hydrogen using corona discharge, characterized by employing the aforementioned corona discharge hydrogen production apparatus, and comprising the following steps: S1. Hydrogen-containing feed gas is introduced from the inlet of the spiral tube at a fixed flow rate. The hydrogen-containing feed gas is at least one of methane, methanol, ethanol, dimethyl ether, and water vapor, or a mixture thereof. S2. Apply a voltage between the high-voltage electrode and the grounding electrode. The voltage type is DC high voltage, AC high voltage or pulsed high voltage, to form a corona discharge plasma field inside the tube. S3. The hydrogen-containing feed gas flowing through the activation section forms a Dean vortex secondary flow when the ratio of the first pitch to the inner diameter of the spiral tube is 1.5 to 4, which promotes radial cross-mixing of the gas and completes the initial activation and cracking. The gas flowing through the reaction section undergoes a continuous cracking reaction to generate hydrogen-rich gas when the ratio of the second pitch to the inner diameter of the spiral tube is 4 to 10. S4. The hydrogen-rich gas generated by the reaction is exported through the output section for collection, separation and purification.

[0019] Furthermore, in step S1, the fixed flow rate ranges from 0.01 m / s to 5 m / s, and before entering the inlet of the spiral tube, the temperature of the hydrogen-containing raw material gas is 25-30°C, and the pressure is standard atmospheric pressure.

[0020] Furthermore, in step S2, the voltage range is 5kV to 30kV.

[0021] Compared with the prior art, the technical solution provided by this invention has the following advantages: (1) This invention adopts a segmented flow channel structure with multi-level gradient variable pitch, variable radius of curvature, or the same radius of curvature. Combined with finely divided reaction zones, the flow field morphology and disturbance intensity can be differentially controlled according to the gas reaction process. It effectively solves the industry pain points commonly found in traditional equipment, such as insufficient activation of raw materials at the front end, uneven distribution of pyrolysis reaction in the middle section, stagnation and accumulation of gas flow at the rear end, and unstable discharge conditions. It can stably maintain the corona discharge state in the tube, enhance the gas phase mass transfer mixing effect, extend the effective reaction time, significantly improve the raw material conversion and utilization rate, and optimize the gas production quality, ultimately achieving a dual improvement in hydrogen production efficiency and discharge operation stability.

[0022] (2) This invention limits the minimum net distance between the high-voltage electrode and the inner wall of the spiral tube to form an optimal discharge gap suitable for corona discharge hydrogen production. This range can avoid arc breakdown and short circuit problems caused by an excessively small gap, and can also prevent a weak electric field and discharge failure caused by an excessively large gap, thus maintaining a uniform and stable corona plasma. At the same time, the electric field strength matches the requirements of the cracking reaction, taking into account both the reaction sufficiency and energy consumption control, so as to achieve efficient and stable continuous hydrogen production. Attached Figure Description

[0023] Figure 1 This is a flowchart of a hydrogen production method using a corona discharge device in one embodiment of this application; Figure 2 This is a schematic diagram of the overall device with consistent helical tube curvature radius in one embodiment of this application; Figure 3 This is a top view of a device with a gradually increasing radius of curvature of a spiral tube in one embodiment of this application; Figure 4 This is a schematic diagram of the reaction section structure in one embodiment of this application; Figure 5 This is a top view of a device with a consistent radius of curvature of the helical tubes in one embodiment of this application; Figure 6 This is a schematic diagram of a high-voltage electrode in one embodiment of this application; Figure 7 This is a schematic diagram of the grounding electrode in one embodiment of this application; Figure 8 This is a diagram showing the secondary flow velocity distribution of the Dean vortex in the main reaction section in one embodiment of this application. Figure 9 This is a diagram showing the secondary flow velocity distribution of the Dean vortex in the rear transition section in one embodiment of this application. Figure 10 This is a schematic diagram of the main flow velocity along the pipe axis at various cross sections of the spiral pipe in one embodiment of this application.

[0024] Explanation of the labels in the diagram: Activation segment 1; Reaction section 2; Front transition section 21; Main reaction section 22; Rear transition section 23; Output segment 3; High voltage electrode 4; Grounding electrode 5. Detailed Implementation

[0025] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0026] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0027] Corona discharge plasma hydrogen production technology refers to the technology that uses a high-voltage electric field to induce corona discharge between electrodes to form a non-thermal equilibrium plasma. The high-energy electrons, ions, free radicals and other active particles generated in the plasma then react with gas molecules in a physicochemical reaction to produce hydrogen. It is a technology with advantages such as low power consumption, rapid response and efficient and compact reactor.

[0028] Specifically, after the hydrogen-containing feed gas enters the spiral flow channel, it undergoes corona discharge under the influence of the strong electric field formed between the high-voltage electrode and the grounding electrode, generating low-temperature non-equilibrium plasma. High-energy electrons in the plasma continuously bombard the feed gas molecules, breaking the chemical bonds in the gas molecules and generating a large number of reactive species such as ions, excited-state particles, and free radicals.

[0029] In existing technologies, while the airflow moves along the axial mainstream within the channel, it is induced by the helical bending structure to generate a Dean vortex secondary flow, forming a radial circulation disturbance within the pipe cross-section. Under the enhanced mixing effect of the Dean vortex secondary flow, the contact time between active particles and reactants is increased, ultimately generating a hydrogen-rich product with hydrogen as the main component, thus completing the hydrogen production process.

[0030] The inventive concept of this application is to: adjust the Dean vortex intensity and gas residence time in stages according to the dynamic requirements of the hydrogen production reaction, so that the flow field characteristics are highly matched with the reaction process, thereby achieving the overall goal of more complete activation of the feed gas, more thorough conversion, less product backmixing, and more stable system operation.

[0031] Example 1 This embodiment provides a corona discharge hydrogen production device, including a spiral tube, a high-voltage electrode 4 and a grounding electrode 5. The spiral tube is divided into an activation section 1, a reaction section 2 and an output section 3 along the gas flow direction. Each section is preferably integrally formed and smoothly connected to form a continuous reaction channel.

[0032] Activation section 1 is located on the gas inlet side and is mainly used for the rapid activation of hydrogen-containing feed gas. Activation section 1 has a first pitch P1 and a first radius of curvature. Relying on the combination of a smaller pitch and radius of curvature, a stronger Dean vortex secondary flow is formed during the gas flow process, which significantly enhances the radial mixing and exchange capacity of the gas flow within the pipe cross-section.

[0033] Reaction section 2 is located downstream of activation section 1 and directly connected to it. It provides sufficient residence time for the activated intermediate products, ensuring complete cracking and conversion of the feed gas. Reaction section 2 has a second pitch P2 and a second radius of curvature. The first pitch P1 < the second pitch P2, and the first radius of curvature ≤ the second radius of curvature. By increasing the pitch and radius of curvature, the gas flow path is extended while maintaining appropriate radial disturbance, thus improving the completeness of the reaction.

[0034] Output section 3 is located downstream of reaction section 2 and is connected to it. It is used to smoothly export the hydrogen-rich products after the reaction is complete. Output section 3 can adopt a straight tube structure or a helical tube structure. When output section 3 adopts a helical tube structure, it has a third pitch P3 and a third radius of curvature, wherein the second pitch < the third pitch and the second radius of curvature ≤ the third radius of curvature, which further stabilizes the flow field and reduces the probability of product backmixing and side reactions.

[0035] In other words, the single-turn axial climb height of the spiral in the activation section 1 is small, the spiral winding is denser, the degree of spatial torsion is more intense, the airflow is sheared and forced to bend within a fixed circumferential deflection radius, the centrifugal effect is stronger, the Dean vortex intensity is significantly improved, the radial tumbling and displacement effect of the gas is excellent, and the activation of the raw material gas can be completed efficiently.

[0036] In reaction section 2, the axial climb height of a single helical turn is increased, the helical arrangement is more relaxed and sparse, the torsional amplitude of the pipeline space is reduced, and both circumferential deflection inertia and centrifugal force are decreased, thus weakening the Dean vortex intensity. Simultaneously, reaction section 2 provides a helical path length several times that of activation section 1, providing sufficient residence time for the deep pyrolysis of intermediate products. As an optional embodiment, the axial length of reaction section 2 along the central axis of the helical tube's spiral profile is 2 to 8 times the axial length of activation section 1. Alternatively, the number of single helical turns in reaction section 2 is 2 to 8 times the number of single helical turns in activation section 1.

[0037] The axial climbing height of a single spiral turn in output section 3 (when a spiral tube is used) is further increased, the spiral arrangement is more extended, the torsion amplitude of the pipeline space is further reduced, the circumferential deflection inertia and centrifugal force are reduced to a lower level, the Dean vortex intensity is significantly weakened, and the airflow is transported forward in a stable laminar state in the pipeline.

[0038] This structure of output section 3 effectively eliminates strong disturbances within the cross-section, preventing back-mixing and secondary reactions of the generated hydrogen-rich products due to violent tumbling, thus ensuring product component stability. Simultaneously, the low flow resistance and smooth gas exit of output section 3 allow for the continuous and stable extraction of the hydrogen-rich products after the reaction, providing stable operating conditions for subsequent collection, separation, and purification.

[0039] As another optional embodiment, the output section 3 adopts a straight pipe structure, which completely restores the flow field to a flat laminar flow, and can also improve the stability and smoothness of product output.

[0040] It is worth noting that, along the radial cross-section direction perpendicular to the spiral tube's spiral profile axis, the cross-sections of the activation section 1, the reaction section 2, and the output section 3, which uses a spiral tube structure, are the same integral circle, or concentric circles or concentric ellipses.

[0041] That is, along the radial section direction perpendicular to the spiral tube's spiral profile axis, the projection of the activation section 1 falls within the projection range of the reaction section 2 or the two completely overlap, and the projection of the reaction section 2 falls within the projection range of the output section 3 or the two completely overlap.

[0042] The structural design of this application ensures that the entire spiral tube is arranged coaxially and concentrically, with a continuous and consistent flow channel cross-section along the entire flow path. The airflow transitions smoothly between sections, resulting in low flow resistance and effectively suppressing local eddies, airflow deflection, and product backmixing, thereby improving the overall flow field stability.

[0043] As an optional embodiment, the first radius of curvature of the activation section 1 is the same as the second radius of curvature of the reaction section 2 and the third radius of curvature of the output section 3 with a helical tube structure. The ratio of the radius of curvature to the inner diameter D of the helical tube is in the range of 2 to 6. The radial cross-section of the helical tube perpendicular to its own axis is circular, that is, the cross-sections of the activation section 1, the reaction section 2, and the output section 3 with a helical tube structure are the same integral circle. Taking this example, the specific structural design of the helical tube is explained: The ratio of the first pitch of the activation section 1 to the inner diameter D of the spiral tube is in the range of 1.5 to 4. This ratio range allows the activation section 1 to form a dense spiral and a strong torsional flow channel, generating a high-intensity Dean vortex secondary flow when the gas flows through, which significantly enhances radial mixing and shearing, meeting the requirements of rapid activation and efficient cracking of the feed gas.

[0044] The ratio of the second pitch of the reaction section 2 to the inner diameter D of the helical tube is in the range of 4 to 10. This ratio range allows for a more relaxed helical arrangement, extending the gas flow path while maintaining appropriate radial disturbance, providing sufficient residence time for intermediate products, and ensuring that the reaction proceeds fully.

[0045] The ratio of the third pitch of output section 3 to the inner diameter D of the helical tube is greater than 10. This ratio range can significantly reduce the degree of flow channel twist, significantly weaken the Dean vortex, and allow the airflow to flow in a stable laminar state, effectively suppressing product backmixing and side reactions, and achieving stable output of hydrogen-rich products.

[0046] In summary, this application addresses common industry shortcomings of traditional spiral tube corona discharge hydrogen production devices, such as fixed flow channel parameters, turbulent gas flow field, poor discharge uniformity, low reaction matching degree, easy retention of hydrogen-rich products, and low hydrogen production efficiency. It innovatively adopts a segmented spiral tube structure with multi-stage gradient variable pitch and variable radius of curvature, achieving a fully optimized structure for the entire process, including raw material gas activation, plasma hydrogen production reaction, and stable extraction of hydrogen-rich products.

[0047] The activation section 1 features a single-tube spiral winding density and high pipeline torsion, which can continuously generate high-intensity Dean vortices and stable secondary swirling effects within the tube. This forces unactivated feed gas near the tube wall to undergo rapid radial exchange across the tube cross-section and continuously deliver it to the high-energy corona discharge active region at the center of the tube. This achieves comprehensive and rapid activation of the feed gas, solving the problems of uneven gas activation, unreacted surface gas, and low initial reaction activity in traditional devices. This lays a solid foundation for subsequent efficient cracking and hydrogen production reactions.

[0048] Downstream of activation section 1 is the reaction section 2 with a large pitch. The flow channel space gradually expands, effectively reducing the gas velocity and preventing the high-speed gas flow from carrying away the plasma charge and breaking down the discharge arc. This ensures the continuous and stable corona discharge, allowing the main hydrogen cracking reaction to proceed fully and uniformly, and significantly improving the hydrogen production reaction conversion rate.

[0049] Output section 3 adopts a spiral structure or straight pipe structure with a larger pitch, which significantly expands the flow channel and can quickly guide the hydrogen-rich mixed gas after the reaction is completed, avoiding the accumulation and retention of products inside the flow channel, effectively suppressing the secondary recombination reaction of hydrogen, ensuring the efficiency of hydrogen production, and at the same time reducing pipeline gas resistance and improving the overall airflow stability.

[0050] The three-stage, progressively increasing parameter design allows for a smooth transition of gas velocity and flow field pressure along the flow direction, avoiding the problems of airflow turbulence and sudden pressure changes that are prone to occur in traditional equal-parameter flow channels. It maintains a stable gas flow state throughout the process, making it suitable for continuous hydrogen production operations.

[0051] As another optional embodiment, the radius of curvature of the helical tube increases progressively along the gas travel direction, and the radial cross-sections perpendicular to the tube axis at each position are distributed in a concentric circular structure. Based on this, the design of the helical tube structure is described as follows: In the activation section 1, the ratio of the first pitch P1 to the inner diameter D of the helical tube is in the range of 1.5 to 4, and the ratio of the first radius of curvature to the inner diameter D of the helical tube is in the range of 0.5 to 3. In the reaction section 2, the ratio of the second pitch P2 to the inner diameter D of the helical tube is in the range of 4 to 10, and the ratio of the second radius of curvature to the inner diameter D of the helical tube is in the range of 3 to 8. In the output section 3, which adopts a helical structure, the ratio of the third pitch to the inner diameter D of the helical tube is greater than 10, and the ratio of the third radius of curvature to the inner diameter D of the helical tube is in the range of 8 to 13.

[0052] The gradually increasing radius of curvature naturally reduces the degree of bend in the flow channel. Combined with the gradually increasing pitch, the centrifugal force experienced by the airflow gradually weakens, allowing the intensity of the Dean vortex secondary flow to decrease smoothly along the pipeline. A uniform inner diameter ensures a constant flow cross-section. The large bends at the front section effectively agitate the airflow, enhancing molecular collision efficiency and facilitating rapid activation and cracking of the feed gas. The smooth flow path at the rear section regulates the airflow, effectively preventing product backmixing and ineffective side reactions, thus improving hydrogen production conversion efficiency.

[0053] More specifically, along the gas flow direction, reaction section 2 sequentially includes a front transition section 21, a main reaction section 22, and a rear transition section 23. The front transition section 21 is connected to the activation section 1, and the rear transition section 23 is connected to the output section 3. The sections are smoothly connected to form a continuous reaction channel without abrupt changes.

[0054] The second pitch includes the front pitch P21 corresponding to the front transition section 21, the main reaction section pitch P22 corresponding to the main reaction section 22, and the rear pitch P23 corresponding to the rear transition section 23. Specifically, the front pitch P21 ≤ the main reaction section pitch P22, and the main reaction section pitch P22 ≤ the rear pitch P23. Along the gas flow direction, the pitch gradually increases, which avoids abrupt changes in flow parameters that could cause gas separation, local eddies, or sudden pressure changes. This ensures a smooth transition of Dean vortex intensity from strong to weak, guaranteeing sufficient raw material conversion and preparing the flow field for subsequent stable discharge.

[0055] The front pitch P21 can be equidistant or gradually increasing along the gas flow direction; similarly, the rear pitch P23 can be equidistant or gradually increasing along the gas flow direction.

[0056] The preferred method is to use a gradually varying pitch, which allows the torsion amplitude, centrifugal force, and Dean vortex intensity of the spiral flow channel to transition smoothly along the flow path, further improving the stability of the flow field and the continuity of the reaction, making the deep cracking process of the feed gas in reaction section 2 more stable and efficient.

[0057] The inner diameter D of the helical tube is set to 4~30mm. This size range provides suitable swirling space and bending and twisting amplitude for the helical tube, enabling the airflow to form a stable and uniformly distributed Dean vortex secondary flow during the flow process, ensuring efficient radial exchange between the fluid on the tube wall and the central region.

[0058] Meanwhile, the outer diameter range allows for a compact overall structure and a reasonable flow path for the spiral tube. This avoids both the dispersion of the flow field and the reduction of the mixing effect caused by an excessively large outer diameter, and the excessive pressure drop along the flow path and the increased difficulty in pipe processing caused by an excessively small outer diameter.

[0059] Correspondingly, along the axial direction of the hollow cylinder or frustum formed by the helical tube, the axial length of the front transition section 21 and the rear transition section 23 is 5mm to 30mm. This can achieve a smooth and gradual change in pitch and curvature, and will not occupy the effective reaction space due to excessively long transition sections, thus ensuring the overall hydrogen production efficiency of the device.

[0060] Example 2 Based on Example 1, in this example, the high-voltage electrode 4 is continuously arranged along the central axis of the spiral tube, and the minimum net distance between the high-voltage electrode 4 and the inner wall of the spiral tube is 2mm to 20mm.

[0061] Electrode spacing is a key parameter affecting the stability of corona discharge and hydrogen production efficiency. Smaller electrode spacing can increase the local electric field strength, making it easier to induce stable corona discharge. However, if the spacing is too small, the electric field strength will be too high, which can easily lead to the transformation of corona discharge into arc discharge, causing uncontrolled discharge, electrode ablation, and abnormal increase in plasma temperature.

[0062] Increasing the electrode spacing can reduce the electric field strength and the risk of arc discharge, but too large a spacing will result in insufficient electric field strength, which will not be able to effectively stimulate corona discharge and activation cracking of the feed gas.

[0063] Therefore, setting a reasonable electrode spacing is crucial for maintaining stable and controllable corona discharge and improving the activation efficiency of raw materials. In this embodiment, the minimum net spacing is controlled between 2mm and 20mm, which can balance the electric field strength, discharge stability, and hydrogen production reaction requirements, thereby achieving efficient, stable, and safe low-temperature plasma hydrogen production.

[0064] The high-voltage electrode 4 is a solid metal electrode. The cross-sectional size of the high-voltage electrode 4 gradually decreases along the gas flow direction, so that the electric field strength in the activation section 1 is greater than that in the reaction section 2, thereby forming a stronger electric field and higher density of active particles in the activation section 1, which matches the working condition requirements of rapid activation of raw material gas.

[0065] The grounding electrode 5 is a continuous metal layer, metal mesh, or metal foil covering the outer wall of the spiral tube; or, the grounding electrode 5 is a line electrode, which is arranged axially along the outer wall of the spiral tube. The grounding electrode 5 and the central high-voltage electrode 4 cooperate to form a radial discharge electric field to achieve local strong electric field excitation.

[0066] The spiral tube is manufactured entirely from insulating material, with a uniform wall thickness controlled between 1mm and 5mm. This insulating material isolates the conductive path between electrodes, preventing leakage and short circuits, and ensuring that corona discharge occurs stably only within the tube's inner chamber.

[0067] Example 3 Based on Examples 1 and 2, this example provides a method for plasma-assisted hydrogen production using the above-described hydrogen production apparatus, specifically including the following steps: S1. Constant-rate gas inlet: The pretreated hydrogen-containing feed gas is continuously introduced into the spiral tube channel at a constant apparent flow rate of 0.01 m / s to 5 m / s. This flow rate range balances gas reaction residence time and device processing efficiency, effectively avoiding incomplete reaction due to excessively high flow rates and product backmixing and accumulation due to excessively slow flow rates. The hydrogen-containing feed gas is at least one of methane, methanol, ethanol, dimethyl ether, and water vapor, and can be flexibly combined with single or mixed feedstocks according to actual hydrogen production conditions to adapt to various hydrogen production scenarios. Furthermore, the temperature of the hydrogen-containing feed gas before entering the spiral tube inlet is 25~30℃, and the pressure is standard atmospheric pressure.

[0068] Furthermore, before the hydrogen-containing feed gas is fed into the spiral tube inlet, the gas temperature is pre-regulated to 25℃~30℃ and the pressure is maintained at standard atmospheric pressure. This ensures a stable and uniform intake state, avoids the interference of temperature and pressure fluctuations on the flow field distribution, discharge effect and cracking reaction process, and ensures the consistency of the hydrogen production process.

[0069] S2. High-voltage discharge initiation: A voltage excitation of 5kV to 30kV is applied between the high-voltage electrode and the ground electrode. The power supply can be DC high voltage, AC high voltage, or pulsed high voltage. A stable corona discharge plasma field is formed inside the spiral tube flow channel through the action of the high-voltage electric field, generating a large number of high-energy electrons and active free radicals. This provides sufficient energy for the chemical bond breaking and activation cracking of the feed gas, ensuring the continuous and stable operation of the low-temperature cracking hydrogen production reaction.

[0070] S3. Segmented gradient reaction: The hydrogen-containing feed gas flows continuously along the spiral tube channel, passing smoothly through the activation section and the reaction section in sequence. Relying on the differentiated pitch structure and flow field characteristics of the two sections, the staged and step-by-step activation cracking hydrogen production reaction is realized.

[0071] In this structure, the ratio of the first pitch to the inner diameter D of the spiral tube in the activation section 1 is controlled to be 1.5 to 4. The spiral is compact and the flow channel has a large torsion amplitude. The airflow can generate a high-intensity and uniform Dean vortex secondary flow during the flow process, which greatly enhances the radial mixing and shear disturbance effect of the fluid, so that the raw material gas and the plasma active particles in the tube can fully contact and collide, quickly complete the molecular bond breaking, and realize the efficient initial activation and primary cracking of the raw material gas.

[0072] The intermediate gas, after initial activation, reacts in section 2. The ratio of the second pitch to the inner diameter D of the spiral tube in section 2 is controlled to be 4-10. Compared with the activation section 1, the spiral structure of section 2 is more extended, and the intensity of the Dean vortex is moderately reduced. This can effectively extend the effective reaction residence time of the gas while maintaining appropriate fluid disturbance and avoiding gas stagnation and stratification. This provides sufficient reaction time and a stable flow field environment for deep cracking and reforming hydrogen production, promotes the full conversion of hydrogen-containing intermediates, continuously generates high-purity hydrogen-rich gas, and significantly improves the overall conversion efficiency of the feed gas.

[0073] S4. Stable Outflow and Collection: After the reaction, the hydrogen-rich gas continuously flows into output section 3. Utilizing the large pitch and gently twisting spiral structure of output section 3, flow field disturbances are significantly reduced, Dean vortex intensity diminishes, and the gas flow is smoothly discharged in a stable laminar state. This effectively avoids secondary side reactions and component attenuation of the generated hydrogen. The discharged hydrogen-rich gas can be directly used for subsequent collection, separation, and purification processes, completing the entire low-temperature plasma hydrogen production process.

[0074] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A corona discharge hydrogen production device, comprising a high-voltage electrode (4) and a grounding electrode (5), characterized in that: It also includes a helical tube along the gas flow direction, the helical tube comprising, The activation segment (1) has a first pitch and a first radius of curvature; The reaction section (2) is located downstream of and connected to the activation section (1), and the reaction section (2) has a second pitch and a second radius of curvature. Output section (3), which is located downstream of and connected to reaction section (2), is used to export hydrogen-rich products; Wherein, the first pitch is less than the second pitch, and the first radius of curvature is less than or equal to the second radius of curvature.

2. The corona discharge hydrogen production device according to claim 1, characterized in that: The output section (3) adopts a straight tube structure or a spiral tube structure; When the output segment (3) is a helical tube structure, the output segment (3) has a third pitch and a third radius of curvature; wherein, the second pitch < the third pitch, and the second radius of curvature ≤ the third radius of curvature.

3. The corona discharge hydrogen production device according to claim 2, characterized in that: Along the gas flow direction, the reaction section (2) includes a front transition section (21), a main reaction section (22), and a rear transition section (23) in sequence; the front transition section (21) is connected to the activation section (1), and the rear transition section (23) is connected to the output section (3); The second pitch includes the front pitch of the corresponding front transition section (21), the main reaction section pitch of the corresponding main reaction section (22), and the rear pitch of the corresponding rear transition section (23), wherein the front pitch ≤ the main reaction section pitch ≤ the rear pitch.

4. The corona discharge hydrogen production device according to claim 3, characterized in that: The inner diameter of the spiral tube is 4~30mm; the axial length of the front transition section (21) and the rear transition section (23) along the central axis of the spiral tube's spiral profile is 5~30mm.

5. The corona discharge hydrogen production device according to claim 1, characterized in that: The high-voltage electrode (4) is continuously arranged along the central axis of the spiral tube, and the minimum net distance between the high-voltage electrode (4) and the inner wall of the spiral tube is 2mm to 20mm.

6. The corona discharge hydrogen production device according to claim 5, characterized in that: The high-voltage electrode (4) is a solid metal electrode. The cross-sectional size of the high-voltage electrode (4) gradually decreases along the gas flow direction, so that the electric field strength of the activation section (1) is greater than that of the reaction section (2).

7. The corona discharge hydrogen production device according to claim 5, characterized in that: The grounding electrode (5) is a metal layer covering the outer wall of the spiral tube.

8. The corona discharge hydrogen production device according to claim 1, characterized in that: The ratio of the first pitch of the activated section (1) to the inner diameter of the spiral tube is in the range of 1.5 to 4. The ratio of the second pitch of the reaction section (2) to the inner diameter of the spiral tube is in the range of 4 to 10. When the output section (3) is a spiral tube structure, the ratio of the third pitch of the output section (3) to the inner diameter of the spiral tube is greater than 10.

9. The corona discharge hydrogen production device according to claim 1, characterized in that: On the radial section perpendicular to the central axis of the spiral tube's spiral profile, the sections of the activation section (1) and the reaction section (2) are concentric circles. The ratio of the first radius of curvature of the activated section (1) to the inner diameter of the helical tube is in the range of 0.5 to 3. The ratio of the second radius of curvature of the reaction section (2) to the inner diameter of the helical tube is in the range of 3 to 8; When the output section (3) is a helical tube structure, the ratio of the third radius of curvature of the output section (3) to the inner diameter of the helical tube is in the range of 8 to 13.

10. A corona discharge hydrogen production device according to claim 1, characterized in that: Along the central axis of the spiral tube, the axial length of the reaction section (2) is 2 to 8 times the axial length of the activation section (1).

11. The corona discharge hydrogen production device according to claim 1, characterized in that: The spiral tube is made of insulating material, and its wall thickness is uniformly set, ranging from 1mm to 5mm.

12. A method for producing hydrogen by corona discharge, characterized in that, The hydrogen production method using the corona discharge hydrogen production apparatus according to any one of claims 1-11 includes the following steps: S1. Hydrogen-containing feed gas is introduced from the inlet of the spiral tube at a fixed flow rate. The hydrogen-containing feed gas is at least one of methane, methanol, ethanol, dimethyl ether, and water vapor, or a mixture thereof. S2. Apply a voltage between the high-voltage electrode and the grounding electrode. The voltage type is DC high voltage, AC high voltage or pulsed high voltage, to form a corona discharge plasma field inside the tube. S3. The hydrogen-containing feed gas flowing through the activation section forms a Dean vortex secondary flow when the ratio of the first pitch to the inner diameter of the spiral tube is 1.5 to 4, which promotes radial cross-mixing of the gas and completes the initial activation and cracking. The gas flowing through the reaction section undergoes a continuous cracking reaction to generate hydrogen-rich gas when the ratio of the second pitch to the inner diameter of the spiral tube is 4 to 10. S4. The hydrogen-rich gas generated by the reaction is exported through the output section for collection, separation and purification.

13. The method for producing hydrogen by corona discharge according to claim 12, characterized in that: In step S1, the fixed flow rate ranges from 0.01 m / s to 5 m / s, and before entering the inlet of the spiral tube, the temperature of the hydrogen-containing raw material gas is 25-30°C and the pressure is standard atmospheric pressure.

14. The method for producing hydrogen by corona discharge according to claim 12, characterized in that: In step S2, the voltage range is 5kV to 30kV.

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