Plasma device for treating industrial wastewater

Abstract

The invention discloses a plasma device for treating industrial wastewater. A plasma reactor of the plasma device comprises a plurality of groups of annular sub-reactors which are arranged in parallel and an electrode fixer, each group of sub-reactors comprises a plurality of annular high-voltage electrodes and foamy copper electrode plates; the annular high-voltage electrodes are vertically aligned and arranged at intervals, and the foamy copper electrode plates are inserted into the middle parts of the annular high-voltage electrodes; a metal plate is arranged between every two adjacent sub-reactors; the foamy copper electrode plate and the metal plate are arranged in parallel and form a plasma reaction electric field with the annular high-voltage electrode; the plurality of groups of sub-reactors are fixed through electrode fixers; liquid flowing out of the water inlet device enters the liquid product collector through the plasma reaction electric field. According to the device, the initial voltage of discharge is reduced, the discharge area is increased, more active particles are generated to degrade pollutants in wastewater, the energy utilization efficiency of the whole device is enhanced, and the effects of high efficiency and low energy consumption are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of plasma wastewater treatment, and in particular to a plasma device for treating industrial wastewater. Background Art

[0002] In recent years, with the rapid development of industrialization in my country, the discharge of toxic and hazardous industrial wastewater has increased significantly. According to statistics, industrial wastewater emissions account for nearly one-third of total sewage discharge, and industrial wastewater contributes over 40% to water pollution, seriously harming the ecological environment. Commonly used wastewater treatment methods mainly include physical and chemical methods. Physical methods are simple to operate, widely applicable, and can effectively recover or filter pollutants, but they cannot completely treat pollutants, and the high cost and potential for secondary pollution cannot be ignored. Chemical treatment methods have better treatment effects on specific pollutants, but the addition of chemical reagents not only increases treatment costs but also may bring additional environmental risks.

[0003] Due to the non-thermal equilibrium characteristics of low-temperature plasma technology, its application in water treatment has been increasingly studied in recent years. Extensive experiments and research have shown that during the low-temperature plasma discharge process, a large number of active species, such as high-energy electrons, ions, atoms, and free radicals, are generated. These active species continuously collide with each other, triggering a variety of chemical reactions, generating a variety of active species with strong oxidizing or reducing properties and ionizing radiation. In particular, plasma discharge at the gas-liquid interface contains active components such as oxidizing molecules, hydrated electrons, and ultraviolet light. These active species interact with organic compounds in the liquid phase, leading to the decomposition of organic pollutants. Furthermore, the plasma reaction occurs at ambient temperature and pressure, avoiding the high energy consumption of high-temperature and high-pressure equipment. Furthermore, the ultraviolet radiation and reactive oxygen species (ROS) generated by the plasma can effectively inactivate bacteria and viruses in wastewater (inactivation rate >99.9%). Furthermore, some technologies can recover heavy metals (such as Cu and Ag) or generate reusable gases (H2 and CO). Therefore, the application of low-temperature plasma in wastewater treatment holds broad application prospects.

[0004] Prior art publication number CN212492881U discloses a pulsed discharge plasma reactor and an organic wastewater treatment device. This device uses a microsecond pulsed high-voltage power supply to generate plasma, thereby achieving highly efficient wastewater degradation. However, the pulsed excitation source has limited output energy and cannot drive a large reactor. Furthermore, it is relatively expensive to manufacture. Furthermore, a large amount of impurities remain after wastewater treatment. The device's overall structure is complex, resulting in high overall costs and difficulty in subsequent maintenance. Publication number CN112616234A discloses a device and method for generating a discharge plasma in water using a direct current source. However, due to the short arc plasma duration and small discharge area formed in this device, it is difficult to achieve effective wastewater treatment results at high flow rates.

[0005] Therefore, while ensuring the efficiency and stability of industrial wastewater treatment, how to achieve cost optimization, green and sustainable development, and effective control of product toxicity in the treatment process has become a key technical problem that needs to be solved urgently. Summary of the Invention

[0006] 1. Technical problems to be solved: In response to the above technical problems, the present invention provides a plasma device for treating industrial wastewater, which is an industrial wastewater treatment device that can achieve efficient treatment, intelligent regulation, simple operation and easy maintenance.

[0007] 2. Technical solution: A plasma device for treating industrial wastewater, characterized in that it includes a water inlet device, a plasma reactor, and a liquid product collector; the water inlet device is provided with a water inlet for admitting industrial wastewater, and the wastewater entering the water inlet device passes through a particle filter and flows into the plasma reactor located below it; the plasma reactor includes multiple groups of parallel-arranged annular sub-reactors and an electrode holder; each group of annular sub-reactors includes multiple annular high-voltage electrodes and a grounded foam copper electrode plate; the multiple annular high-voltage electrodes are aligned and arranged at intervals in the upper and lower parts, and the foam copper electrode plate is inserted in the middle part; a metal plate is provided between adjacent sub-reactors; the foam copper electrode plate and the metal plate are arranged in parallel and form a plasma reaction electric field with the annular high-voltage electrodes; the multiple groups of sub-reactors are fixed by the electrode holder; the liquid flowing out of the water inlet device enters the liquid product collector through the plasma reaction electric field.

[0008] Furthermore, the annular high-voltage electrode is in the shape of a long "U" character, with all four sides being cylindrical dielectric layers, and high-voltage electrodes are symmetrically provided on two long sides; the high-voltage electrode is a spiral metal wire or a cylindrical metal mesh, which is coaxially sleeved in the dielectric layer tube, and the extension direction of the high-voltage electrode is the same as the extension direction of the long side; the wiring port of the high-voltage electrode is located at one of the short sides.

[0009] Furthermore, the electrode holder includes a square outer shell, a metal plate, a side sealing cover and a ground electrode fixing plate; the plasma reactor is arranged in the inner cavity of the outer shell, and the metal plate is located between two adjacent sub-reactors; the ground electrode fixing plate is detachably wrapped around the foam copper electrode plate; the two vertical sides of the ground electrode fixing plate are provided with grooves for placing the short sides of the annular high-voltage electrode; the two long sides of the annular high-voltage electrode are connected by two sections of detachable dielectric layer tubes; the side sealing cover is located on one side of the outer shell, and its inner wall is provided with a groove for installing the metal plate and a groove for installing the ground electrode fixing plate; when installing or replacing the annular high-voltage electrode, the two sections of the dielectric layer tube on the long side are respectively connected or separated from the left and right ends of the ground electrode fixing plate.

[0010] Furthermore, the square shell of the electrode holder is a hollow cube with an opening at the top, with an outer length of 200~220 mm, an outer width of 200~220 mm, and a wall thickness of 6~7 mm; the dielectric layer tube of the annular high-voltage electrode is a hollow polytetrafluoroethylene rod with an outer diameter of 20~22 mm, a thickness of 2~3 mm, and a length of 160~180 mm, and its four sides are connected by connectors; the outer diameter of the high-voltage electrode is 16~18 mm, the inner diameter is 12~14 mm, and the length is 180 mm; the dimensions of the foam copper electrode plate are: 170~190 mm in length, 170~190 mm in width, and 2mm~3mm in thickness. During installation, after it is put on the grounding electrode fixing plate, the annular high-voltage electrode is installed and fixed to the corresponding groove, and the overall structure can be inserted into the cavity of the electrode holder shell from the upper end of the shell; the length and width of the foam copper electrode plate after being put on the grounding electrode fixing plate are both 200~220 mm, and the thickness is 6~7 mm.

[0011] Furthermore, the distance between the surface of the metal plate and the annular high-voltage electrode is 1-3 mm; the distance between the foam copper electrode plate and the annular high-voltage electrode is 1-3 mm.

[0012] Furthermore, each group of annular sub-reactors includes three annular high-voltage electrodes; and each device includes two groups of annular sub-reactors.

[0013] Furthermore, the water inlet device is square and is arranged at the upper end of the electrode holder housing. Its water inlet is also provided with a circulating pipe water inlet; the circulating pipe water inlet is connected to the water outlet of the liquid product collector through a circulating pump.

[0014] Furthermore, the liquid product collector is square and is arranged at the bottom of the electrode holder housing. It is equipped with a water quality detector and an activated carbon filter; the water quality detector detects the treated industrial wastewater, and if it meets the emission standards, the main drain outlet is opened; if the test does not meet the standards, the liquid will re-enter the water inlet device through the circulation pipe under the action of the circulation pump for treatment.

[0015] 3.Beneficial effects: (1) The present invention provides a plasma device for treating industrial wastewater, which forms a three-electrode structure through a unique ring-shaped high-voltage electrode, a grounded foam copper electrode plate, and a metal plate structure, and uses the ring electrode as a high-voltage electrode to generate an asymmetric electric field, optimize the electric field distribution, reduce the energy required for discharge, and form a multi-level discharge channel, thereby increasing the discharge area and reducing the overall energy consumption. At the same time, a three-electrode dielectric barrier discharge plasma device with multiple microchannel discharges is formed, wherein the physical microchannel (structural channel) includes a porous medium permeation channel, wherein the pores connected inside the foam copper electrode plate form a material transmission nanochannel; the discharge microchannel (plasma channel) includes a filamentary discharge microchannel, a surface discharge microchannel, and a body discharge microchannel; the electric field modulation microchannel (virtual channel) includes (1) an asymmetric electric field line channel, i.e., a radial non-uniform electric field is formed between the ring electrode and the flat ground electrode; and (2) a three-electrode coupling channel, i.e., a third electrode (suspended or biased electrode) induces a secondary discharge microchannel between the ring-ground main channel. Multiple microchannel discharges not only reduce the initial discharge voltage, increase the discharge area, and generate more active particles for degrading pollutants in wastewater, but also enhance the energy utilization efficiency of the overall device, achieving high efficiency and low energy consumption.

[0016] (2) The present invention provides a plasma device for treating industrial wastewater, which uses foam copper as the electrode material and a special structure between the electrode and the electrode. Under the condition of the same input power and electrode length, an effective discharge area twice the length of the electrode can be formed. Combined with the special porous structure of the foam copper electrode plate, the residence time of pollutants in the wastewater in the plasma area is greatly improved, which is beneficial to obtaining a better treatment effect. The treated liquid can reach different indicators through circulation, thereby enhancing the wastewater treatment effect and improving its universality, meeting the treatment needs of different fields.

[0017] (3) The present invention provides a plasma device for treating industrial wastewater. The foam copper electrode plate used has the characteristics of a porous structure. Under the excitation of the alternating electric field, in addition to generating spatial body discharge with the corresponding annular high-voltage electrode, discharge can also be generated inside the pores of its structure, forming more discharge channels, which is conducive to the generation of active substances. In addition, the porous structure can effectively prolong the residence time of pollutants in the wastewater in the discharge plasma area, enhance the contact time between pollutants and plasma, and help improve the wastewater treatment effect.

[0018] (4) The present invention provides a plasma device for treating industrial wastewater. The electrode structure is modular. The number of electrodes can be flexibly adjusted to meet specific needs in different scenarios. It has strong universality and is easy to replace, maintain and inspect later. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is an overall schematic diagram of the plasma device of the present invention; Figure 2 Schematic diagram of the structure of the plasma reactor in the present invention; Figure 3 Schematic diagram of the ring-shaped high-voltage electrode in the present invention; Figure 4 is a cross-sectional view of a plasma device according to the present invention; Figure 5 Schematic diagram of the liquid product collector of the present invention; Figure 6 is a schematic diagram of the side sealing cover of the present invention; Figure 7 Schematic diagram of the ground electrode fixing plate in the present invention.

[0020] Figure 8 This is a flow chart of industrial wastewater treatment using the present invention in a specific embodiment; Figure 9 This is a diagram showing the effect of adjusting the input voltage on the reaction characteristics in the verification example; Figure 10 This is a diagram showing the effect of different frequencies on hydrogen peroxide production in the verification example; Figure 11 This is a diagram showing the effect of cycle times and number of electrodes on hydrogen peroxide production in the verification example. Figure 12 This is a graph showing the hydrogen peroxide content of copper foam and copper plate under the same working conditions in the verification example.

[0021] Explanation of the accompanying symbols: 1. Water inlet; 2. Particle filter; 3. Electrode holder; 4. Metal plate; 5. Water quality detector; 6. Liquid product collector; 601. Water inlet of the circulation pipe; 7. Circulation pipe; 8. Circulation pump; 9. Side sealing cover; 10. Annular high-voltage electrode; 101. Dielectric layer cylinder; 102. Spiral metal wire or cylindrical metal mesh; 103. Connection port of high-voltage electrode; 104. Connector; 11. Foam copper electrode plate; 12. Activated carbon filter; 13. Water outlet; 14. Ground electrode fixing plate. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings.

[0023] As attached Figure 1 To the attached Figure 7As shown, a plasma device for treating industrial wastewater is characterized in that it includes a water inlet device, a plasma reactor, and a liquid product collector; the water inlet device is provided with a water inlet 1 for introducing industrial wastewater, and the wastewater entering the water inlet device passes through a particle filter 2 and flows into the plasma reactor located below it; the plasma reactor includes multiple groups of parallel-arranged annular sub-reactors and an electrode holder 3; each group of annular sub-reactors includes multiple annular high-voltage electrodes 10 and a grounded foam copper electrode plate 11; the multiple annular high-voltage electrodes are aligned and spaced apart, and the middle part thereof is inserted with a foam copper electrode plate; a metal plate 4 is provided between adjacent sub-reactors; the foam copper electrode plate and the metal plate are arranged in parallel and form a plasma reaction electric field with the annular high-voltage electrodes; the multiple groups of sub-reactors are fixed by the electrode holder; the liquid flowing out of the water inlet device enters the liquid product collector 6 through the plasma reaction electric field.

[0024] Furthermore, the annular high-voltage electrode is shaped like a long "U" (Chinese character for "U"). All four sides are cylindrical dielectric layers, with high-voltage electrodes symmetrically positioned on the two long sides. The high-voltage electrode is a spiral metal wire or cylindrical metal mesh 102, coaxially sleeved within the dielectric layer tube 101. The high-voltage electrode extends in the same direction as the long sides. The high-voltage electrode connection port 103 is located on one of the short sides. Reference numeral 104 in the figure represents the connector connecting the long and short sides.

[0025] Furthermore, the electrode holder includes a square outer shell, a metal plate, a side sealing cover 9 and a ground electrode fixing plate 14; the plasma reactor is arranged in the inner cavity of the outer shell, and the metal plate is located between two adjacent sub-reactors; the ground electrode fixing plate is detachably wrapped around the foam copper electrode plate; the two vertical sides of the ground electrode fixing plate are provided with grooves for placing the short sides of the annular high-voltage electrode; the two long sides of the annular high-voltage electrode are connected by two sections of detachable dielectric layer tubes; the side sealing cover is located on one side of the outer shell, and its inner wall is provided with a groove for installing the metal plate and a groove for installing the ground electrode fixing plate; when installing or replacing the annular high-voltage electrode, the two sections of the dielectric layer tube on the long side are respectively docked or separated from the left and right ends of the ground electrode fixing plate.

[0026] Furthermore, the square shell of the electrode holder is a hollow cube with an opening at the top, with an outer length of 200~220 mm, an outer width of 200~220 mm, and a wall thickness of 6~7 mm; the dielectric layer tube of the annular high-voltage electrode is a hollow polytetrafluoroethylene rod with an outer diameter of 20~22 mm, a thickness of 2~3 mm, and a length of 160~180 mm, and its four sides are connected by connectors; the outer diameter of the high-voltage electrode is 16~18 mm, the inner diameter is 12~14 mm, and the length is 180 mm; the dimensions of the foam copper electrode plate are: 170~190 mm in length, 170~190 mm in width, and 2mm~3mm in thickness. During installation, after it is put on the grounding electrode fixing plate, the annular high-voltage electrode is installed and fixed to the corresponding groove, and the overall structure can be inserted into the cavity of the electrode holder shell from the upper end of the shell; the length and width of the foam copper electrode plate after being put on the grounding electrode fixing plate are both 200~220 mm, and the thickness is 6~7 mm.

[0027] Furthermore, the distance between the surface of the metal plate and the annular high-voltage electrode is 1-3 mm; the distance between the foam copper electrode plate and the annular high-voltage electrode is 1-3 mm.

[0028] Furthermore, each group of annular sub-reactors includes three annular high-voltage electrodes; and each device includes two groups of annular sub-reactors.

[0029] Furthermore, the water inlet device is square and is arranged at the upper end of the electrode holder housing. Its water inlet is also provided with a water inlet 601 of the circulation pipe 7; the water inlet of the circulation pipe is connected to the water outlet 13 of the liquid product collector through a circulation pump 8.

[0030] Furthermore, the liquid product collector is square and is arranged at the bottom of the electrode holder housing. It is equipped with a water quality detector 5 and an activated carbon filter 12; the water quality detector detects the treated industrial wastewater, and if it meets the discharge standards, the main drain outlet is opened; if the test does not meet the standards, the liquid will re-enter the water inlet device through the circulation pipe under the action of the circulation pump for treatment. Specific embodiments

[0031] As attached Figure 8 As shown in the figure, it is a flow chart of using this device to treat industrial wastewater, which can be divided into five steps: feeding untreated industrial wastewater into the device, turning on the power to adjust parameters, plasma treating the wastewater, detecting the product, and discharging the industrial wastewater that meets the standards.

[0032] This device utilizes copper foam as the first ground electrode, a circular high-voltage electrode, and a metal plate as the second ground electrode, forming a three-electrode dielectric barrier discharge (DBD) device. A discharge plasma region forms between the copper foam electrode plate and the circular high-voltage electrode. The rich porous structure of the copper foam electrode plate creates multiple discharge channels under an alternating electric field, increasing the contact time between pollutants and the plasma. Furthermore, the circular high-voltage electrode design creates a higher electric field in the arc portion, facilitating the formation of discharge channels and thus reducing the required breakdown voltage. Simultaneously, at the same input voltage, a discharge plasma also forms between the circular high-voltage electrode and the metal plate. This not only increases the effective discharge plasma region and the contact area between the industrial wastewater and the reactor, enhancing the device's pollutant treatment capacity while also reducing energy consumption. Combined with a detection and circulation system, this device allows for multiple treatments of industrial wastewater that does not meet discharge standards, ensuring optimal treatment results. Furthermore, all electrodes used in this device can be easily disassembled and reassembled, significantly reducing the difficulty and cost of equipment maintenance.

[0033] Verification Example 1: This verification example is used to verify that the regulation of the input voltage of this device can control the core parameters of discharge intensity, active species generation efficiency and H2O2 yield. The results are shown in the attached Figure 9 As shown in the experiment, it is shown that by optimizing the voltage parameters, the concentration of active substances such as H2O2 and hydroxyl radicals (·OH) can be significantly increased, thereby enhancing the oxidation and degradation of organic pollutants and ultimately achieving more efficient wastewater treatment. Input voltage is an important reaction condition affecting wastewater treatment. By adjusting the input voltage of the reaction, the content of active substance hydrogen peroxide generated by deionized water discharge was studied. The experimental results are shown in the figure below. Figure 7 The experiment shows that the hydrogen peroxide content generated gradually increases with increasing input voltage, reaching a maximum of 27.39%. The energy efficiency initially decreases, reaching a maximum of 12.24 g / kWh at an input voltage of 13 kV. The hydrogen peroxide content reaches its highest point of 27.39% at an input voltage of 15 kV.

[0034] Verification Example 2: This verification example is used to verify the effect of different power supply frequencies on hydrogen peroxide production. In the plasma wastewater treatment system, the adjustment of power supply frequency is one of the key parameters for controlling the reaction process. By adjusting the discharge frequency, the micro-discharge density and electron energy distribution can be effectively changed, thereby affecting the generation rate of active species such as hydroxyl radicals (·OH), and ultimately achieving precise control of organic matter degradation efficiency and hydrogen peroxide (H2O2) yield. This study adjusts the input frequency to explore its effect on hydrogen peroxide production. The experimental results are as follows. Figure 10As shown in the figure, as the discharge frequency increases, the hydrogen peroxide production first increases and then decreases. This is probably because in the low-frequency range, the number of discharges per unit time increases significantly with increasing frequency, forming more uniform micro-discharges. However, in the high-frequency range, the thermal effect generated by the discharge causes the decomposition of hydrogen peroxide, resulting in a decrease in hydrogen peroxide production.

[0035] Verification Example 3: This verification example is used to verify the effect of the number of cycles and the number of electrodes of this device on the production of hydrogen peroxide. In the plasma wastewater treatment system, the amount of hydrogen peroxide (H2O2) produced shows a nonlinear cumulative characteristic with the reaction time. By adjusting the number of cycles, the residence time of the sewage in the plasma activation area can be controlled, thereby optimizing the free radical contact efficiency, and extending the residence time to promote the mass transfer reaction between active substances such as OH and sewage. This study increases the number of cycles and the number of high-voltage electrodes, and increases the reaction time of deionized water in the reaction area to explore the effect of reaction time on the performance of wastewater treatment reactions. The experimental results are as follows. Figure 11 As shown in the figure, as the number of cycles increases, the reaction time increases accordingly, and the production of hydrogen peroxide shows an upward trend. This shows that as the number of cycles increases and the reaction time increases, the production of hydrogen peroxide will also increase, and the sewage treatment effect will be better.

[0036] Verification Example 4: This verification case is used to verify the hydrogen peroxide content produced by this device using foam copper and copper plate under the same working conditions. The results are shown in the attached Figure 12 As shown, using copper foam as an electrode material at the same power frequency can produce more hydrogen peroxide active species. This is because the copper foam's reticular structure can break large bubbles into microbubbles, increasing the gas-liquid contact efficiency, which is very beneficial for hydrogen peroxide production. Furthermore, the greatest advantage of copper foam is the increased specific surface area brought about by its three-dimensional porous structure. Ordinary copper plate electrodes have limited contact area, while the internal pores of copper foam significantly increase the gas-liquid-solid three-phase reaction interface.

[0037] Although the present invention has been disclosed above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone skilled in the art can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims of this application.

Claims

1. A plasma device for treating industrial wastewater, characterized in that: The invention comprises a water inlet device, a plasma reactor and a liquid product collector; the water inlet device is provided with a water inlet for introducing industrial wastewater, and the wastewater entering the water inlet device flows into the plasma reactor located below it after passing through a particle filter; the plasma reactor comprises multiple groups of parallel-arranged annular sub-reactors and an electrode holder; each group of annular sub-reactors comprises multiple annular high-voltage electrodes and a grounded foam copper electrode plate; the multiple annular high-voltage electrodes are aligned and spaced apart, with the foam copper electrode plate inserted in the middle; a metal plate is provided between adjacent sub-reactors; the foam copper electrode plate and the metal plate are arranged in parallel and form a plasma reaction electric field with the annular high-voltage electrodes; the multiple groups of sub-reactors are fixed by the electrode holder; the liquid flowing out of the water inlet device enters the liquid product collector through the plasma reaction electric field.

2. A plasma device for treating industrial wastewater according to claim 1, characterized in that: The annular high-voltage electrode is in the shape of a long "U" character, with all four sides being cylindrical dielectric layers, and high-voltage electrodes are symmetrically provided on the two long sides; the high-voltage electrode is a spiral metal wire or a cylindrical metal mesh, which is coaxially sleeved in the dielectric layer cylinder, and the extension direction of the high-voltage electrode is the same as the extension direction of the long side; the wiring port of the high-voltage electrode is located at one of the short sides.

3. The plasma device for treating industrial wastewater according to claim 2, characterized in that: The electrode holder includes a square outer shell, a metal plate, a side sealing cover and a ground electrode fixing plate; the plasma reactor is arranged in the inner cavity of the outer shell, and the metal plate is located between two adjacent sub-reactors; the ground electrode fixing plate is detachably wrapped around the foam copper electrode plate; the two vertical sides of the ground electrode fixing plate are provided with grooves for placing the short sides of the annular high-voltage electrode; the two long sides of the annular high-voltage electrode are connected by two sections of detachable dielectric layer tubes; the side sealing cover is located on one side of the outer shell, and its inner wall is provided with a groove for installing the metal plate and a groove for installing the ground electrode fixing plate; when installing or replacing the annular high-voltage electrode, the two sections of the dielectric layer tube on the long side are respectively connected or separated from the left and right ends of the ground electrode fixing plate.

4. The plasma device for treating industrial wastewater according to claim 3, wherein: The square shell of the electrode holder is a hollow cube with an opening at the top, with an outer length of 200~220 mm, an outer width of 200~220 mm, and a wall thickness of 6~7 mm; the dielectric layer tube of the annular high-voltage electrode is a hollow polytetrafluoroethylene rod with an outer diameter of 20~22 mm, a thickness of 2~3 mm, and a length of 160~180 mm, and its four sides are connected by connectors; the outer diameter of the high-voltage electrode is 16~18 mm, the inner diameter is 12~14 mm, and the length is 180 mm; the dimensions of the foam copper electrode plate are: 170~190 mm in length, 170~190 mm in width, and a thickness of 2mm~3mm. During installation, after it is put on the grounding electrode fixing plate, the annular high-voltage electrode is installed and fixed to the corresponding groove, and the overall structure can be inserted into the cavity of the electrode holder shell from the upper end of the shell; the length and width of the foam copper electrode plate after being put on the grounding electrode fixing plate are both 200~220 mm, and the thickness is 6~7 mm.

5. The plasma device for treating industrial wastewater according to claim 4, characterized in that: The distance between the surface of the metal plate and the annular high-voltage electrode is 1-3 mm; the distance between the foam copper electrode plate and the annular high-voltage electrode is 1-3 mm.

6. The plasma device for treating industrial wastewater according to claim 1, characterized in that: Each group of annular sub-reactors includes three annular high-voltage electrodes; each device includes two groups of annular sub-reactors.

7. The plasma device for treating industrial wastewater according to claim 3, characterized in that: The water inlet device is square and is arranged at the upper end of the electrode holder housing. Its water inlet is also provided with a circulating pipe water inlet; the circulating pipe water inlet is connected to the water outlet of the liquid product collector through a circulating pump.

8. The plasma device for treating industrial wastewater according to claim 3, characterized in that: The liquid product collector is square and is located at the bottom of the electrode holder housing. It is equipped with a water quality detector and an activated carbon filter. The water quality detector detects the treated industrial wastewater. If the discharge standard is met, the main drain outlet is opened. If the test does not meet the standard, the liquid will re-enter the water inlet device through the circulation pipe under the action of the circulation pump for treatment.

Images