Integrated spark-dielectric barrier coupling plasma processing device

Abstract

The invention belongs to the technical field of plasma reactors, and particularly relates to an integrated spark-dielectric barrier coupled plasma treatment device, which realizes spark discharge and dielectric barrier discharge in the same reaction cavity, and is particularly suitable for collaborative purification of gas generated in solid sample treatment and reaction processes. The device comprises a dielectric tube, a hollow high-voltage electrode serving as an air inlet, an umbrella-shaped electrode positioned at the lower end of the high-voltage electrode, a high-voltage electrode wound outside the tube and a plasma power supply. Spark discharge is formed between the hollow high-voltage electrode and the hemispherical head of the umbrella-shaped electrode and is used for solid sample treatment; dielectric barrier discharge is formed between the umbrella-shaped electrode handle part and the high-voltage electrode outside the tube through the dielectric tube wall and is used for gas purification. The device is simple in structure, does not need a liquid electrode, avoids the complexity of a liquid circulation system, has the advantages of high reliability, simplicity and convenience in operation and low cost, and is suitable for the integrated process of metal oxide reduction, solid waste treatment, waste gas purification and the like.

Description

Technical Field

[0001] This invention belongs to the field of plasma reactor technology, specifically relating to an integrated spark-dielectric barrier coupled plasma treatment device that realizes spark discharge and dielectric barrier discharge in the same reaction chamber, and is particularly suitable for the synergistic purification of solid sample processing and gas generated during the reaction process. Background Technology

[0002] Dielectric barrier discharge (DBD) and spark discharge are two common methods for generating atmospheric pressure plasma. DBD offers advantages such as uniform discharge, good stability, and suitability for continuous gas processing, while spark discharge is characterized by high local energy density and high electron temperature, making it suitable for solid sample processing and high-energy activation processes. Existing technologies include devices combining spark discharge and DBD, such as patent CN118175711A, which discloses a spark-dielectric barrier coupling device using a multilayer coaxial dielectric tube and a circulating electrolyte solution as the grounding electrode. However, such devices typically suffer from the following shortcomings: (1) Complex structure: It requires multiple layers of coaxial media pipes, liquid circulation pumps, liquid storage tanks and sealing systems, resulting in high manufacturing costs and assembly difficulties; (2) Inconvenient operation and maintenance: Liquid electrolytes are prone to leakage, evaporation, concentration changes and corrosion of pipelines, and need to be replenished and replaced regularly, making them unsuitable for long-term stable operation; (3) Limited coupling mode of discharge region: The shape and position of liquid electrode are not easy to control precisely, which limits the flexibility of optimal spatial matching and coordinated control between spark discharge region and dielectric barrier discharge region.

[0003] Therefore, it is necessary to provide a plasma device that does not require liquid electrodes, has a simplified structure, and can achieve orderly coordination of spark discharge and dielectric barrier discharge within a single reaction chamber. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a simple, liquid-electrode-free, and stable spark-dielectric barrier coupled plasma device. By employing an umbrella-shaped solid electrode with a handle and a hemispherical head as a common reference electrode, a spark discharge is generated between the electrode and the hollow high-voltage electrode above it. Simultaneously, the handle and the electrode wound around the outside of the tube form a dielectric barrier discharge through the dielectric tube wall. This allows for spatial connection and electrical correlation of the two discharges within the same reaction chamber, while the parameters can be independently adjusted, thus achieving the integration of solid waste treatment with waste gas purification or catalytic reaction.

[0005] Technical solution of the present invention: To achieve the above objectives, the present invention adopts the following technical solution: An integrated spark-dielectric barrier coupled plasma processing device includes: The dielectric tube is vertically installed and made of electrically insulating material, with its upper and lower ends sealed to form a reaction chamber; A hollow high-voltage electrode is coaxially disposed inside the dielectric tube, with its upper end extending out of the dielectric tube to form an air inlet and its lower end located inside the dielectric tube. The grounding electrode is an umbrella-shaped electrode, including a handle and a hemispherical head, located inside the dielectric tube. The umbrella-shaped electrode is fixedly disposed below the hollow high-voltage electrode along the axis and maintains a gap with the hollow high-voltage electrode to form a spark discharge area between them. The handle of the umbrella-shaped electrode extends out of the dielectric tube and serves as a common reference electrode. An external high-voltage electrode is configured as a metal electrode wound around the outer wall of the dielectric tube, which together with the dielectric tube wall forms a dielectric barrier discharge region; An air outlet is located at the lower end of the medium tube; The first plasma power source has its high-voltage output terminal connected to the hollow high-voltage electrode and its low-voltage output terminal connected to the umbrella-shaped electrode handle, and is used to generate spark discharge between the hollow high-voltage electrode and the umbrella electrode. The second plasma power supply has its high-voltage output terminal connected to the external high-voltage electrode and its low-voltage output terminal connected to the umbrella-shaped electrode handle, and is used to generate dielectric barrier discharge between the external electrode and the umbrella-shaped electrode handle. The spark discharge region is located upstream of the flow direction of the reacting gas, and the dielectric barrier discharge region is located downstream of the spark discharge region, so that the reacting gas undergoes the synergistic treatment of spark discharge and dielectric barrier discharge in the same reaction chamber.

[0006] The radius of the hemispherical head of the umbrella-shaped electrode is 5-50 mm; The external electrode is a metal wire, metal mesh, or metal foil, and is wound along the axial direction of the dielectric tube; The umbrella-shaped electrode hemispherical head is provided with several through holes, the diameter of which is 0.2-1mm; The medium tube is a quartz tube, an alumina tube, or a ceramic tube; The plasma power supply is an AC power supply or a pulse power supply, with an output voltage of 2-20kV and a frequency of 5-50kHz; The hollow high-voltage electrode also serves as the gas inlet channel for the reaction gas, allowing the gas to flow along the axial direction of the device. The projection of the umbrella-shaped electrode handle in the axial direction at least partially overlaps with the projection area of ​​the external high-voltage electrode.

[0007] The beneficial effects of this invention are: (1) Simplified structure: A single dielectric tube and solid electrode structure is adopted to avoid liquid electrode system; (2) Synergistic discharge: The spark discharge region and the dielectric barrier discharge region are arranged in an orderly manner in the same reaction chamber to achieve synergistic high-energy treatment and uniform purification; (3) Stable operation: The common reference electrode structure allows the parameters of the two discharge modes to be adjusted independently without interference; (4) Strong applicability: It is applicable to both solid sample processing and simultaneous purification of gases generated during the reaction. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of an existing spark discharge plasma processing device.

[0009] Figure 2 This is a schematic diagram of an existing dielectric barrier discharge plasma processing device.

[0010] Figure 3 This is a schematic diagram of an existing spark discharge-dielectric barrier discharge series plasma treatment device.

[0011] Figure 4 This is a schematic diagram of an integrated spark-dielectric barrier coupled plasma processing device.

[0012] In the diagram: 1. Air inlet; 2. Air outlet; 3. High-voltage electrode a; 4. High-voltage electrode b; 5. Grounding electrode; 6. Dielectric tube; 7. Umbrella-shaped electrode hemispherical head; 8. Umbrella-shaped electrode handle; 9. Through hole; 10. Flexible tube. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0014] Figure 1 This is a schematic diagram of an existing spark discharge plasma treatment device. The device includes an inlet 1, an outlet 2, a high-voltage electrode a3, a grounding electrode 5, and a dielectric tube 6. The dielectric tube 6 serves as the reaction chamber. The high-voltage electrode a3, a hollow tubular structure, is located in the upper part of the dielectric tube 6 and acts as the inlet 1, through which the reaction gas enters the reaction chamber. The grounding electrode 5 is located in the lower part of the dielectric tube 6, and the bottom of the dielectric tube 6 has an outlet 2. A spark discharge zone is formed between the high-voltage electrode a3 and the grounding electrode 5, where the reaction gas undergoes high-energy discharge treatment and is then directly discharged through the outlet 2. The grounding electrode 5 is an umbrella-shaped electrode, including an umbrella-shaped electrode hemispherical head 7 and 8, and an umbrella-shaped electrode handle 8. The umbrella-shaped electrode hemispherical head 7 is located in the middle of the dielectric tube 6, and has multiple evenly distributed through holes 9.

[0015] Figure 2This is a schematic diagram of an existing dielectric barrier discharge plasma treatment device. The device includes an inlet 1, an outlet 2, a high-voltage electrode b4, a grounding electrode 5, and a dielectric tube 6. The dielectric tube 6 serves as the reaction chamber and also as the inlet 1, through which the reactive gas enters the reaction chamber. The grounding electrode 5 is located in the lower part of the dielectric tube 6, and the outlet 2 is located at the bottom of the dielectric tube 6. The high-voltage electrode b4 is located on the outer wall of the lower part of the dielectric tube 6. A uniform dielectric barrier discharge region is formed along the dielectric tube 6 between the high-voltage electrode b4 and the grounding electrode 5. The reactive gas is processed after flowing through this region and discharged through the outlet 2.

[0016] Figure 3 This is a schematic diagram of an existing spark discharge-dielectric barrier discharge series plasma treatment device. The device is a split-series structure, sequentially including a spark discharge module (corresponding to...). Figure 2 Device) and dielectric barrier discharge module (corresponding) Figure 3 (Device). The outlet 2 at the bottom of the spark discharge module and the inlet 1 at the top of the dielectric barrier discharge module are connected by a hose 10. The reaction gas flows through the two independent reaction chambers and is respectively treated by spark discharge and dielectric barrier discharge.

[0017] Figure 4 This is a schematic diagram of the integrated spark-dielectric barrier coupled plasma processing device according to the present invention. The device mainly includes an inlet 1, an outlet 2, a high-voltage electrode a3, a high-voltage electrode b4, a grounding electrode 5, and a dielectric tube 6. The dielectric tube 6 serves as the reaction chamber. The high-voltage electrode a3, a hollow tubular structure, is located in the upper part of the dielectric tube 6 and serves as the inlet 1, through which the reaction gas enters the reaction chamber. The grounding electrode 5 is located in the lower part of the dielectric tube 6, and the bottom of the dielectric tube 6 has an outlet 2. The high-voltage electrode b4 is located on the outer wall of the lower part of the dielectric tube 6. The grounding electrode 5 is an umbrella-shaped electrode, including an umbrella-shaped electrode hemispherical head 7 and 8 and an umbrella-shaped electrode handle 8. The umbrella-shaped electrode hemispherical head 7 is located in the middle of the dielectric tube 6, and has multiple evenly distributed through holes 9. The reaction gas enters through the inlet 1, is processed sequentially by the spark discharge zone and the dielectric barrier discharge zone, and is discharged through the outlet 2.

[0018] When using it, you will also need to: The first plasma power source is an AC high-voltage power source. Its high-voltage output terminal is connected to the hollow high-voltage electrode, and its low-voltage output terminal is connected to the umbrella-shaped electrode handle. It is used to generate spark discharge between the hollow high-voltage electrode and the umbrella electrode. The second plasma power source is an AC high-voltage power source. Its high-voltage output terminal is connected to the external high-voltage electrode, and its low-voltage output terminal is connected to the umbrella-shaped electrode handle. It is used to generate dielectric barrier discharge between the external electrode and the umbrella-shaped electrode handle.

[0019] The following steps are performed using the apparatus of the present invention for material processing: The solid sample to be processed is placed in the hemispherical head of the umbrella-shaped electrode, and / or the gas to be processed is introduced; A first voltage is applied between the hollow high-voltage electrode and the umbrella-shaped electrode to generate a spark discharge to treat the solid sample and / or preliminarily activate the gas; Simultaneously or sequentially, a second voltage is applied between the external electrode and the umbrella-shaped electrode handle to generate a dielectric barrier discharge, thereby homogenizing or deeply purifying the gaseous products after spark discharge treatment.

[0020] Example 1 (Spark discharge – dielectric barrier discharge synergistic generation) like Figure 4 As shown, the spark discharge coupled dielectric barrier discharge plasma device provided in this embodiment includes: A quartz dielectric tube with an inner diameter of 50 mm and a length of 250 mm is vertically installed, with its upper and lower ends sealed with high-temperature resistant insulating material to form a reaction chamber; A hollow high-voltage electrode, made of stainless steel, with an outer diameter of 6 mm and an inner diameter of 4 mm, is coaxially arranged inside the medium tube. Its upper end extends out of the medium tube as the inlet for the reaction gas, and its lower end is located inside the medium tube. The grounding electrode is an umbrella-shaped electrode, including a handle and a hemispherical head. The hemispherical head of the umbrella-shaped electrode is made of stainless steel with a radius of 20 mm and is coaxially arranged below the hollow high-voltage electrode. A gap of about 15 mm is maintained between the lower end of the hollow high-voltage electrode and the hemispherical head of the umbrella-shaped electrode to form a stable spark discharge region. The handle of the umbrella-shaped electrode extends out of the dielectric tube and serves as a common reference electrode. An external high-voltage electrode, made of copper wire, is tightly wound axially along the outer wall of the dielectric tube, with a winding width of about 60 mm, to form a dielectric barrier discharge region together with the dielectric tube wall. The outlet is located at the lower end of the medium pipe and is used to discharge the treated gas. The first plasma power source is an AC high-voltage power source. Its high-voltage output terminal is connected to the hollow high-voltage electrode, and its low-voltage output terminal is connected to the umbrella-shaped electrode handle. It is used to generate spark discharge between the hollow high-voltage electrode and the umbrella electrode. The second plasma power source is an AC high-voltage power source. Its high-voltage output terminal is connected to the external high-voltage electrode, and its low-voltage output terminal is connected to the umbrella-shaped electrode handle. It is used to generate dielectric barrier discharge between the external electrode and the umbrella-shaped electrode handle.

[0021] During the experiment, argon gas was introduced into the device at a flow rate of 500 mL / min, and the first plasma power supply (output voltage 15 kV, frequency 20 kHz) and the second plasma power supply (output voltage 10 kV, frequency 20 kHz) were started.

[0022] It can be observed that a bright and stable spark discharge is formed between the hollow high-voltage electrode and the hemispherical head of the umbrella-shaped electrode, while a uniform and stable blue dielectric barrier discharge is formed between the handle of the umbrella-shaped electrode and the external electrode wrapped around the outer wall of the dielectric tube. The reactive gas flows from top to bottom along the axial direction of the device, and is successively subjected to the combined treatment of the spark discharge zone and the dielectric barrier discharge zone.

[0023] This circuit connection method allows spark discharge and dielectric barrier discharge to share the same reference electrode, but the voltage, frequency, and phase of the two power supplies can be adjusted independently without interfering with each other, thus achieving flexible matching of discharge modes.

[0024] Example 2 (Reduction of Metal Oxides) Based on the apparatus described in Example 1, 0.5 g of iron oxide powder was placed on the hemispherical head surface of the umbrella-shaped electrode as the solid sample to be treated. Hydrogen gas was introduced into the apparatus at a flow rate of 200 mL / min. Two plasma power supplies were activated, enabling the apparatus to operate in a combined spark discharge and dielectric barrier discharge mode. The spark discharge region directly acted on the iron oxide powder, providing high-energy electrons and a localized high-temperature environment to promote the reduction reaction of iron oxide. Samples were taken for analysis after the reaction lasted for 10 minutes, and the results showed that the reduction rate of iron oxide reached over 95%.

[0025] The small amount of water vapor and by-product gases generated during the reaction are carried by the airflow into the downstream dielectric barrier discharge region, where they are further decomposed and processed under the action of uniform plasma, achieving the integrated effect of simultaneous purification of solid sample processing and reaction waste gas.

[0026] Example 3 (Dry Reforming Reaction) Based on the apparatus described in Example 1, a catalyst sample is placed on the surface of the hemispherical head of the umbrella-shaped electrode. A mixture of methane and carbon dioxide is introduced into the apparatus at a flow rate of 300 mL / min for both methane and carbon dioxide, for dry reforming reaction. The first and second plasma power supplies are activated, allowing the reaction gas to pass sequentially through the spark discharge region and the dielectric barrier discharge region along the axial direction.

[0027] Experimental results show that the high-energy discharge environment provided by the spark discharge region significantly promotes the initial activation of the reactant gas, while the uniform plasma environment provided by the downstream dielectric barrier discharge region is conducive to the continuous progress of the reaction and the suppression of side reactions. The methane conversion rate reached 93%, demonstrating the advantages of the synergistic effect of spark discharge and dielectric barrier discharge.

[0028] Comparative Example 1 Under the experimental conditions of Example 2, only the first plasma power supply (spark discharge mode, corresponding to...) was turned on. Figure 1 (Apparatus). Due to the lack of downstream dielectric barrier discharge to treat the reaction tail gas, the water vapor and byproducts generated during the reaction could not be effectively purified, resulting in a decrease in the iron oxide reduction rate to 58%.

[0029] Comparative Example 2 Under the experimental conditions of Example 2, only the second plasma power supply (DBD mode, corresponding to...) was turned on. Figure 2 (Apparatus). Due to the lack of high-energy activation provided by spark discharge, the reduction rate of iron oxide powder was only 12%.

[0030] Comparative Example 3 Under the experimental conditions of Example 2, the following was adopted: Figure 1 Spark discharge device and Figure 2 The dielectric barrier discharge devices are connected in series (corresponding to) Figure 3 The results showed that the two discharge methods failed to achieve effective synergy in physically separated cavities, and the reduction rate of iron oxide powder dropped to 56%. This further proves that in the same reaction cavity, dielectric barrier discharge plays an important role in the real-time treatment of reaction tail gas and in improving the reduction effect.

[0031] Comparative Example 4 Under the experimental conditions of Example 3, only the first plasma power supply (spark discharge mode, corresponding to...) was turned on. Figure 1 (Apparatus). The methane conversion rate was 59%, a decrease of approximately 34 percentage points compared to the synergistic mode of Example 3.

[0032] Comparative Example 5 Under the experimental conditions of Example 3, only the second plasma power supply (DBD mode, corresponding to...) was turned on. Figure 2 (Apparatus). The methane conversion rate was 40%, a decrease of approximately 53 percentage points compared to the synergistic mode of Example 3.

[0033] Comparative Example 6 Under the experimental conditions of Example 3, the following was adopted: Figure 2 Spark discharge device and Figure 3 The dielectric barrier discharge devices are connected in series (corresponding to) Figure 3 The methane conversion rate was 77%, which is still lower than the integrated coupling device of this invention (93%). This indicates that simply connecting the two discharge methods in series in a separate device cannot achieve a true synergistic effect, while the coupling design of this invention within the same cavity can significantly improve reaction performance.

[0034] Comparative Example 7 (Hemispherical head without umbrella-shaped electrodes) Based on the apparatus of Example 1, the hemispherical head of the umbrella-shaped electrode was removed, leaving only the stalk electrode. Experimental results showed that a stable large-area spark discharge could not be formed, resulting in a significant reduction in sample processing efficiency.

[0035] Comparative Example 8 (using liquid electrodes) Referring to prior art document CN118175711A, a circulating electrolyte system is used to replace the externally wound electrode of this invention. Although two types of discharge can be achieved, the device has a complex structure, slow start-up, and problems such as electrolyte evaporation, concentration fluctuations, and system corrosion exist, resulting in lower long-term operational stability than this invention.

Claims

1. An integrated spark-dielectric barrier coupled plasma processing device, characterized in that, The integrated spark-dielectric barrier coupled plasma processing device includes: The dielectric tube is vertically installed and made of electrically insulating material, with its upper and lower ends sealed to form a reaction chamber; A hollow high-voltage electrode is coaxially disposed inside the dielectric tube, with its upper end extending out of the dielectric tube to form an air inlet and its lower end located inside the dielectric tube. The grounding electrode is an umbrella-shaped electrode, including a handle and a hemispherical head, located inside the dielectric tube. The umbrella-shaped electrode is fixedly disposed below the hollow high-voltage electrode along the axis and maintains a gap with the hollow high-voltage electrode to form a spark discharge area between them. The handle of the umbrella-shaped electrode extends out of the dielectric tube and serves as a common reference electrode. An external high-voltage electrode is configured as a metal electrode wound around the outer wall of the dielectric tube, which together with the dielectric tube wall forms a dielectric barrier discharge region; The air outlet is located at the lower end of the medium tube.

2. An integrated spark-dielectric barrier coupled plasma processing device, characterized in that, The integrated spark-dielectric barrier coupled plasma processing device further includes: The first plasma power source has its high-voltage output terminal connected to the hollow high-voltage electrode and its low-voltage output terminal connected to the umbrella-shaped electrode handle, and is used to generate spark discharge between the hollow high-voltage electrode and the umbrella electrode. The second plasma power source has its high-voltage output terminal connected to the external high-voltage electrode and its low-voltage output terminal connected to the umbrella-shaped electrode handle, and is used to generate dielectric barrier discharge between the external electrode and the umbrella-shaped electrode handle.

3. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The spark discharge region is located upstream of the flow direction of the reacting gas, and the dielectric barrier discharge region is located downstream of the spark discharge region, so that the reacting gas undergoes the synergistic treatment of spark discharge and dielectric barrier discharge in the same reaction chamber.

4. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The radius of the hemispherical head of the umbrella-shaped electrode is 5-50 mm.

5. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The external electrode is a metal wire, metal mesh, or metal foil, and is wound along the axial direction of the dielectric tube.

6. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The umbrella-shaped electrode hemispherical head is provided with several through holes, the diameter of which is 0.2-1mm.

7. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The medium tube is a quartz tube, an alumina tube, or a ceramic tube.

8. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The plasma power source is an AC power source or a pulse power source, with an output voltage of 2-20kV and a frequency of 5-50kHz.

9. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The hollow high-voltage electrode also serves as the inlet channel for the reaction gas, allowing the gas to flow axially along the device.

10. The integrated spark-dielectric barrier coupled plasma processing device according to claim 1, characterized in that, The projection of the umbrella-shaped electrode handle in the axial direction at least partially overlaps with the projection area of ​​the external high-voltage electrode.

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