Airflow self-driven rotary sliding arc plasma ammonia hydrogen burner

Abstract

The airflow self-driven rotary sliding arc plasma ammonia hydrogen burner comprises a grounding cylinder and a high-voltage conducting rod, a flow equalizing nozzle and a one-way anti-backfire valve are arranged at the upper end and the lower end in the grounding cylinder, the high-voltage conducting rod is coaxially arranged in the grounding cylinder, and the high-voltage conducting rod is located between the flow equalizing nozzle and the one-way anti-backfire valve; a plurality of rotating electrodes are rotationally arranged on the high-voltage conducting rod, each rotating electrode comprises a plurality of metal blades, and gaps are reserved between the metal blades and the inner wall of the grounding cylinder; a plurality of arcing metal strips are axially arranged on the inner wall of the grounding cylinder, and an insulating layer is filled between every two adjacent arcing metal strips; the bottom of the grounding cylinder is provided with an isolation grounding section made of a high-strength insulating material. The flow equalizing nozzle and an anti-backfire one-way gas flow valve system are combined, efficient cracking of ammonia gas by rotating sliding arc plasma for hydrogen production is achieved, a motor is prevented from being used for driving an electrode, and the problems that a power source of a V-shaped structure electrode system is high in cost and energy consumption, and the electrode is seriously corroded are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of plasma, and particularly relates to an air-flow self-driven rotating sliding arc plasma ammonia-hydrogen combustor. Background Art

[0002] Ammonia (NH3) has a high hydrogen storage density (the mass fraction of hydrogen is 17.6%), a high energy density (the maximum specific energy for cracking is 5.59 kWh / kg), a low price, is easy to liquefy (it can be liquefied at a pressure of 0.8 Mpa at room temperature), has good safety (the ignition range is relatively narrow, and it has a pungent smell, so leakage is easy to identify, and there is no hydrogen embrittlement phenomenon in hydrogen storage and transportation), and a low storage and transportation cost. The complete cracking product only has the target product H2 (the volume concentration can reach 75%) and the by-product N2, with zero carbon emissions. It is considered to be the most potential and best safe hydrogen alternative energy carrier at present. The ammonia decomposition hydrogen production reaction is , and the hydrogen production process is endothermic and has a large energy demand. Generally used catalytic thermal decomposition ammonia hydrogen production technology has a good conversion effect. However, due to the high operating temperature, the effective cracking temperature of the reaction depends on the catalyst used. The activity ranking of different metals for ammonia cracking is: Ru>Rh>Ni>Co>Ir>Fe>>Pt>Cr>Pd>Cu>>Te, Se, Pb. And the more active K-Ru / MgO-CNTs catalyst can reach a H2 production rate of 585 ml / min at 350°C g catal. , when the ammonia feed space velocity is 60000 ml / h g catal. , the ammonia conversion rate can reach about 80% at 400°C and more than 99% at 450°C. However, noble metal ammonia cracking catalysts are expensive and have poor economy. Although non-noble metal catalysts are cheap, their activity is relatively low. To completely crack ammonia, a very high reaction temperature must be used. For example, the operating temperature of nickel-based catalysts needs to exceed 1000°C, and other catalysts also need a temperature of at least 650°C - 700°C to reach a relatively reasonable conversion level. At the same time, this technical equipment also faces problems such as a long preheating time and a large adiabatic system. Therefore, developing new technologies that can meet ammonia decomposition hydrogen production at a lower temperature or alternative processes has become an important exploration direction.

[0003] Discharge plasma is rich in high-energy electrons, and the electron energy distribution range is wide, which is easy to meet the energy threshold for ammonia decomposition hydrogen production reaction and activate the catalyst active sites, breaking through the thermodynamic reaction limit, and showing unique advantages in the activation and cracking of highly chemically inert molecules (such as NH3, CO2, benzene, etc.). It has become a potential stock and research hotspot for non-thermal decomposition ammonia hydrogen production in recent years, and is expected to break through the high reaction temperature limitation of catalytic thermal decomposition ammonia hydrogen production technology.

[0004] As a typical local thermal equilibrium plasma discharge method, the sliding arc discharge technology has been introduced into the research of ammonia cracking for hydrogen production due to its advantages such as high reaction rate, operation at atmospheric pressure, fast startup, and low dependence on catalysts.

[0005] In existing sliding arc discharge devices, the sliding arc generating electrodes are either a fixed V-shaped structure or use a motor to drive the electrodes to rotate to generate arc plasma. The arc of the fixed electrode structure often has a long maintenance time, and the large current poses challenges to the driving power supply, increasing the cost of plasma equipment; for the plasma generation structure with motor-driven electrode rotation, due to high-voltage discharge, it will bring high reverse bias and large current injection to the motor system, posing serious challenges to the stable and reliable operation of the motor, becoming the bottleneck of such sliding arc devices. For example, Patent CN112483243A discloses an ammonia engine based on plasma on-line cracking, ignition, and combustion assistance. This technology quickly reformats ammonia fuel by introducing sliding arc plasma, regulates the ammonia / hydrogen ratio, and uses plasma ignition and combustion assistance to significantly improve combustion stability and combustion efficiency. However, the sliding arc plasma generator of this device uses a coaxial V-shaped electrode structure, with the high-voltage electrode being a rod and the ground electrode being a reduced cylinder. This structure relies on generating an arc at the minimum electrode gap, and the arc drifts axially under the action of temperature rise to form a sliding arc. The entire process has a low degree of control, and the electrode corrosion is serious. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes an air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner, which is a sliding arc discharge plasma generation technology and device with air-flow self-driven rotation of the high-voltage electrode. Combining a uniform flow nozzle and an anti-backfire one-way air valve system, it realizes the efficient cracking of ammonia to hydrogen by rotating sliding arc plasma, avoids using a motor to drive the electrode, and solves the problems of high cost, high energy consumption of the power supply, and serious electrode corrosion of the V-shaped electrode system.

[0007] The technical solution of the present invention to solve the above problems is: an air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner, which is characterized in that: It includes a grounding cylinder and a high-voltage conductive rod. A uniform flow nozzle and a one-way anti-backfire valve are provided at the upper and lower ends inside the grounding cylinder. The high-voltage conductive rod is coaxially arranged inside the grounding cylinder, and the high-voltage conductive rod is located between the uniform flow nozzle and the one-way anti-backfire valve. A plurality of rotating electrodes are rotatably provided on the high-voltage conductive rod. The rotating electrodes include a plurality of metal blades, and there is a gap between the metal blades and the inner wall of the grounding cylinder; a plurality of arc-starting metal strips are axially provided on the inner wall of the grounding cylinder, and an insulating layer is filled between adjacent two arc-starting metal strips; an isolation grounding section made of high-strength insulating material is provided at the bottom of the grounding cylinder.

[0008] Further, an air guide shell is coaxially arranged outside the grounding cylinder, and the annular space between the air guide shell and the grounding cylinder is used to introduce oxygen.

[0009] Further, the above-mentioned flow equalizing nozzle includes a ceramic body, and a number of through holes are uniformly arranged in the ceramic body. Metal sheets are arranged on the upper and lower end faces of the ceramic body, and holes corresponding to the through holes of the ceramic body are arranged on the metal sheets.

[0010] Further, the surface of the metal sheet at the upper end of the ceramic body is covered with a proton exchange membrane, and the material is a metal proton membrane such as a palladium-copper alloy membrane.

[0011] Further, the above-mentioned rotating electrode is installed on the high-voltage conductive rod through a non-damping bearing.

[0012] Further, a spring top bead is arranged on the high-voltage conductive rod to limit the non-damping bearing, which is easy to repair, disassemble and install.

[0013] Further, the above-mentioned rotating electrode includes three blades, and the included angle between each blade and the horizontal plane is 15° - 45°.

[0014] Further, the included angle between two adjacent blades is 120°, and the distance from the end of the blade to the inner wall of the grounding cylinder is 5 - 15 mm.

[0015] Further, the above-mentioned multiple rotating electrodes are arranged at equal intervals on the high-voltage conductive rod, and the distance between two adjacent rotating electrodes is 5 mm - 20 mm.

[0016] Further, an arc starting metal strip is arranged on the inner wall of the grounding cylinder every 120°, and the arc starting metal strip is arranged alternately with the insulating layer.

[0017] Advantages of the present invention: Compared with the traditional DC arc, dielectric barrier discharge, thermal nozzle or microwave plasma hydrogen production device, the present device has the following remarkable beneficial effects: (1) The present invention proposes an air flow self-driven rotating sliding arc plasma ammonia-hydrogen combustor, which adopts a coaxial structure design, combines a rotating electrode and a sliding arc discharge form, and can realize dynamic and high-energy plasma excitation during the flow of a mixed gas (such as ammonia gas and inert gas); (2) The device combines a rotating electrode and a sliding arc. The arc dynamically expands on the electrode surface to form a rotating sliding arc, effectively expanding the plasma action area, improving the ammonia conversion efficiency, while slowing down the electrode ablation and improving the system stability and service life; (3) The gas enters the reaction cavity from bottom to top, is cracked in the discharge area and then discharged from the top flow equalizing nozzle, which can quickly take away the reaction products, prevent side reactions and flashback phenomena, and improve the hydrogen production purity and system operation safety; (4) By setting up a one-way anti-backfire valve and an isolation grounding section, the present invention realizes effective electrical isolation and flame blocking between the high-pressure area and the intake system, ensuring the safety of operators and equipment. (5) The device has a compact structure and distinct modules, and is applicable to laboratory research, small hydrogen energy devices or distributed plasma application systems, with good practical prospects and popularization value. Description of the Drawings

[0018] Figure 1 It is the internal structure diagram of the air-flow self-driven rotating sliding arc plasma ammonia-hydrogen combustor. Figure 2 It is the top view of the flow equalizing nozzle. Figure 3 It is the structure diagram of the rotating electrode. Figure 4 It is the top view of the grounding cylinder.

[0019] In the figure: 1 - flow equalizing nozzle, 2 - rotating electrode, 3 - high-voltage conducting rod, 4 - grounding cylinder, 5 - air guiding shell, 6 - one-way anti-backfire valve, 7 - isolation grounding section, 8 - through hole, 9 - metal blade, 10 - insulating layer, 11 - arc starting metal strip. Specific Embodiments

[0020] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0021] The present invention proposes an air-flow self-driven rotating sliding arc plasma ammonia-hydrogen combustor, which utilizes the synergistic effect of a high-voltage electric field and a rotating electrode, combines gas flow dynamic regulation and multiple safety protections to achieve stable generation, controllable sliding and efficient utilization of the arc. The device rotates the electrode to extend the arc path and prevent local ablation of the electrode, and at the same time optimizes the gas flow distribution through a flow equalizing structure to improve the energy conversion efficiency.

[0022] See the attached Figures 1 - 4, the self-driven rotating sliding arc plasma ammonia-hydrogen burner includes a grounding cylinder 4 and a high-voltage conductive rod 3. At the upper and lower ends inside the grounding cylinder 4, there are a flow equalizing nozzle 1 and a one-way anti-backfire valve 6. The high-voltage conductive rod 3 is coaxially fixed inside the grounding cylinder 4, and the high-voltage conductive rod 3 is located between the flow equalizing nozzle 1 and the one-way anti-backfire valve 6. A plurality of rotating electrodes 2 are rotatably arranged on the high-voltage conductive rod 3. The rotating electrode 2 includes a plurality of metal blades 9, and there is a gap between the metal blades 9 and the inner wall of the grounding cylinder 4. Axially on the inner wall of the grounding cylinder 4, there are several arc-starting metal strips 11, and an insulating layer 10 is filled between two adjacent arc-starting metal strips 11; at the bottom of the grounding cylinder 4, there is an isolation grounding section 7 made of a high-strength insulating material.

[0023] Specifically, the isolation grounding section 7 is made of a high-strength insulating material (such as PTFE or ceramic), and its height is 1 cm to 5 cm. The arc-starting metal strips 11 can be fixed in the grounding cylinder 4 by an inlay method, and the insulating layer 10 (with a thickness of about 1 mm) is fixed in the grounding cylinder 4 by a coating or embedding method.

[0024] As a preferred embodiment of the present invention, see Figure 1 , coaxially outside the grounding cylinder 4, there is an air diversion housing 5. The annular space between the air diversion housing 5 and the grounding cylinder 4 is used to introduce oxygen, and the oxygen flow also ensures the directivity of the flame.

[0025] Specifically, the outer diameter of the air diversion housing is 20 - 50 mm, and the wall thickness is 0.5 - 1 mm; the outer diameter of the grounding cylinder is adjustable from 16 - 46 mm, and the wall thickness is 1 mm.

[0026] As a preferred embodiment of the present invention, see Figure 2 , the above-mentioned flow equalizing nozzle 1 includes a ceramic body. A number of through holes 8 are uniformly arranged inside the ceramic body. Metal sheets are fixed on the upper and lower end faces of the ceramic body by bonding or countersunk screws, and the metal sheets are provided with holes corresponding to the through holes 8 of the ceramic body. The high-voltage conductive rod 3 is embedded in the center of the ceramic body with a depth of 5 mm.

[0027] Specifically, the diameter of the flow equalizing nozzle is 10 - 30 mm, the height is 10 mm - 50 mm, and the diameter of the holes on the metal sheet is 0.1 mm - 1 mm.

[0028] As a preferred embodiment of the present invention, the surface of the metal sheet at the upper end of the above-mentioned ceramic body is covered with a proton exchange membrane to separate and purify hydrogen. The material of the proton exchange membrane is a metal proton membrane such as a palladium-copper alloy membrane, and the thickness of the metal proton membrane is 1 mm.

[0029] As a preferred embodiment of the present invention, the above-mentioned rotating electrode 2 is mounted on the high-voltage conductive rod 3 through a non-damping bearing, and a spring top bead is provided on the high-voltage conductive rod 3 for limiting the non-damping bearing, which is easy to repair, disassemble and install.

[0030] As a preferred embodiment of the present invention, refer to Figure 3 , the above-mentioned rotating electrode 2 includes three blades, the angle between each blade and the horizontal plane is 15° to 45°, the angle between adjacent two blades is 120°, and the distance from the end of the blade to the inner wall of the grounding cylinder is 5 to 15 mm.

[0031] As a preferred embodiment of the present invention, refer to Figure 1 , the above-mentioned multiple rotating electrodes 2 are arranged at equal intervals on the high-voltage conductive rod 3, and the distance between adjacent two rotating electrodes is 5 mm to 20 mm.

[0032] As a preferred embodiment of the present invention, refer to Figure 4 , an arc-starting metal strip 11 is arranged on the inner wall of the above-mentioned grounding cylinder 4 every 120°, and the arc-starting metal strip 11 is arranged alternately with the insulating layer 10.

[0033] The working principle of the gas flow self-driven rotating sliding arc plasma ammonia-hydrogen burner provided by the present invention is as follows: The gas flow direction is from bottom to top. Ammonia (NH3) enters from the bottom of the burner and first passes through the isolation grounding section 7 arranged at the lower part, which effectively electrically isolates the entire discharge cavity from the external grounding system to prevent the power supply from discharging to the ground through an accidental path. After the gas enters the device, the gas continues to flow upward and passes through the one-way anti-backfire valve 6. This component is a mechanical or thermosensitive structure that can effectively prevent the flame or high-temperature gas generated during the discharge process from flowing back into the gas supply pipeline, ensuring the safety of the system operation. The gas continues to rise and enters the discharge area. This area is composed of the built-in high-voltage conductive rod 3, the rotating electrode 2 rotatably connected to the high-voltage conductive rod 3, and the outer grounding cylinder 4 to form a discharge electrode pair. The metal blades 9 on the rotating electrode 2 form a rotating motion under the action of the gas flow impact. An arc is formed by breakdown between the rotating electrode 2 and the grounding cylinder 4, and the arc is driven to slide along the arc-starting metal strip 11 on the inner wall of the grounding cylinder 4. The insulating layer 10 can inhibit the arc from being too long, play a role in stabilizing and pulse-modulating the arc, and improve the plasma action range and energy utilization efficiency. Finally, the gas generated by the reaction cracking is discharged from the flow equalizing nozzle 1 at the top, improving the uniformity and speed of the ejected gas, and providing a good basis for subsequent gas sampling or analysis.

[0034] In summary, the present invention provides an air-flow self-driven rotating sliding arc plasma ammonia-hydrogen combustor, which adopts a coaxial structure design and mainly includes seven functional modules such as a flow equalizing nozzle, a rotating electrode, a high-voltage conductive rod, a grounding cylinder, an air guiding shell, a one-way flashback preventer, and an isolation grounding section, which are combined to form a reactor with a compact structure, a stable flow field, and good electrical isolation. The device realizes the cracking of ammonia through the air-flow guidance from bottom to top and the high-voltage rotating sliding arc discharge form, and combines the nozzle to control the gas discharge, with the characteristics of high energy efficiency, compact structure, safety and reliability, and is suitable for energy conversion applications such as ammonia plasma cracking for hydrogen production.

[0035] The above are only the embodiments of the present invention, and do not limit the protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related system fields, shall be included in the protection scope of the present invention by the same token.

Claims

1. An air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner, characterized in that: It includes a grounding cylinder (4) and a high-voltage conductive rod (3). At the upper and lower ends inside the grounding cylinder (4), a flow equalizing nozzle (1) and a one-way anti-backfire valve (6) are provided. The high-voltage conductive rod (3) is coaxially arranged inside the grounding cylinder (4), and the high-voltage conductive rod (3) is located between the flow equalizing nozzle (1) and the one-way anti-backfire valve (6). A plurality of rotating electrodes (2) are rotatably arranged on the high-voltage conductive rod (3). The rotating electrode (2) includes a plurality of metal blades (9), and there is a gap between the metal blade (9) and the inner wall of the grounding cylinder (4); A plurality of arc-starting metal strips (11) are axially arranged on the inner wall of the grounding cylinder (4), and an insulating layer (10) is filled between two adjacent arc-starting metal strips (11); The bottom of the grounding cylinder (4) is provided with an isolation grounding section (7) made of a high-strength insulating material.

2. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 1, characterized in that: An air guiding outer shell (5) is coaxially arranged outside the grounding cylinder (4), and the annular space between the air guiding outer shell (5) and the grounding cylinder (4) is used for introducing oxygen.

3. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 1, characterized in that: The flow equalizing nozzle (1) includes a ceramic body, and a plurality of through holes (8) are uniformly arranged inside the ceramic body. Metal sheets are provided on the upper and lower end faces of the ceramic body, and holes corresponding to the through holes (8) of the ceramic body are provided on the metal sheets.

4. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 3, characterized in that: The surface of the metal sheet at the upper end of the ceramic body is covered with a proton exchange membrane.

5. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 1, characterized in that: The rotating electrode (2) is installed on the high-voltage conductive rod (3) through a non-damping bearing.

6. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 5, characterized in that: A spring bead is provided on the high-voltage conductive rod (3) for limiting the non-damping bearing.

7. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 1, characterized in that: The rotating electrode (2) includes three metal blades (9), and the included angle between each metal blade (9) and the horizontal plane is 15° to 45°.

8. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 7, characterized in that: The included angle between two adjacent metal blades (9) is 120°, and the distance from the end of the metal blade (9) to the inner wall of the grounding cylinder is 5 to 15 mm.

9. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to any one of claims 1 to 8, characterized in that: A plurality of rotating electrodes (2) are arranged at equal intervals on the high-voltage conductive rod (3).

10. The air-flow self-driven rotating sliding arc plasma ammonia-hydrogen burner according to claim 9, characterized in that: An arc-starting metal strip (11) is arranged on the inner wall of the grounding cylinder (4) every 120°, and the arc-starting metal strips (11) and the insulating layer (10) are arranged alternately.

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