Gas-liquid two-phase dielectric barrier discharge device, electrode and electrode manufacturing method

Abstract

The present invention provides a gas-liquid two-phase dielectric barrier discharge device, an electrode and a method for manufacturing the electrode. The gas-liquid two-phase dielectric barrier discharge device includes a barrel and a discharge electrode; the barrel can rotate around its axis; the discharge electrode is suspended in the barrel and a gap is left between the discharge electrode and the side wall of the barrel; the angle between the discharge electrode and the axis of the barrel is equal to the angle between the side wall of the barrel and its axis. Compared with the prior art, the gas-liquid two-phase dielectric barrier discharge device provided by the present invention adopts the outer wall rotation method, and uses centrifugal force to realize static non-aqueous electrodes and dynamic water electrodes. At the same time, in order to solve the problem that the liquid surface has a certain fluctuation under rotation, the discharge water phase contact surface is also increased. The rotating outer wall material is changed to a porous ceramic material, and the porous characteristics of the ceramic are used to relatively increase the liquid phase surface. The circulating spray method is adopted to update the water phase, and part of the liquid is dispersed in the gas phase, which further absorbs the active components in the air.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment equipment, and in particular to a gas-liquid two-phase dielectric barrier discharge device, an electrode and a method for manufacturing the electrode. Background Art

[0002] Dielectric discharge plasma water treatment is a new type of water treatment oxidation technology, which plays an important role in the fields of harmless treatment of organic wastewater, non-processing disinfection and activation of water. The traditional dielectric barrier discharge water treatment device passes wastewater between two parallel dielectric barrier discharge devices. Generally, air, Ar, N2 and other gases are used as working media, and the water phase is only used as the object to be treated. The generated plasma enters the water phase through gas or liquid mass transfer. The whole process has problems such as uneven and unstable plasma, free radicals cannot be effectively utilized in time, and active particles are not in sufficient contact with the water phase. The gas-liquid two-phase dielectric barrier discharge device uses the water to be treated as an electrode, and the discharge area is in direct contact with the water phase. At the same time, the water phase can effectively reduce the temperature of the discharge area. It is a more efficient plasma water phase treatment method.

[0003] However, the above technologies also have the following problems:

[0004] 1. When static treatment is used, the liquid surface in contact with the discharge area remains basically unchanged, which also means that most of the plasma reacts effectively to the water phase in contact, and then diffuses the generated active radicals to the rest of the water phase through the water phase. For active radicals that decay quickly, they decay before they can play an effective role, and the efficiency is far from being maximized. When dynamic treatment is used, the movement of the electrode will increase the insulation difficulty of the overall system. The activity of the water phase causes large fluctuations in the static liquid surface, affecting the stability of the discharge and the uniformity of the plasma.

[0005] 2. The utilization rate of active groups in the dielectric gas is not high. The dielectric gas of dielectric barrier discharge is air, Ar, and N2. When air is used, its possible application range is wider. Dielectric barrier discharge forms plasma in the gas phase between the two electrodes, and the concentration of active groups in the gas phase is the highest. When a water electrode is used, the plasma in the near-water area is efficiently utilized, but the utilization rate of the gas phase plasma in the non-water electrode area is not high.

[0006] 3. Heat release of non-aqueous phase discharge electrodes. The heat generation of dielectric barrier discharge electrodes is a difficult problem in the industry. There is no unified answer to the specific principle. However, by changing the dielectric properties of dielectric barrier discharge and the air gap inside the electrode, the heat release problem of the electrode can be greatly improved. The discharge efficiency and the service life of the electrode can be improved.

[0007] 4. The liquid phase contact surface problem in the discharge area. When the electrode structure of the non-aqueous phase is determined, the larger the contact surface between the discharge area and the liquid phase, the higher the efficiency of generating plasma. Conventional water electrodes can only increase the discharge surface by increasing the number of non-aqueous phase electrodes to ensure the stability of the water phase liquid surface. The power requirements for dielectric barrier discharge are higher. Summary of the invention

[0008] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a gas-liquid two-phase dielectric barrier discharge device, which can effectively solve the problem of the stability of the liquid surface of the water phase electrode when it is dynamic.

[0009] The gas-liquid two-phase dielectric barrier discharge device provided by the present invention comprises a drum and a discharge electrode; the drum can rotate around its axis; the discharge electrode is suspended in the drum and a gap is left between the discharge electrode and the side wall of the drum; the angle between the discharge electrode and the axis of the drum is equal to the angle between the side wall of the drum and its axis.

[0010] The present invention adopts the method of outer wall rotation to solve the problem of the stability of the liquid surface of the water phase electrode in the dynamic state. At the same time, the surface viscosity of the outer wall rotation is used to drive the air flow, thereby improving the utilization efficiency of the active plasma in the discharge area.

[0011] Preferably, the side wall of the barrel is made of porous ceramic or a ceramic ring made of porous ceramic is arranged on the inner surface of the side wall of the barrel; a gap is left between the discharge electrode and the ceramic ring, and the angle between the discharge electrode and the axis of the ceramic ring is equal to the angle between the inner wall of the ceramic ring and its axis.

[0012] By adopting centrifugal force + siphon of porous ceramic pores and controlling the water volume, water is evenly distributed on the surface of porous ceramics. At the same time, by utilizing the large specific surface area of ​​porous ceramics, the contact area between the discharge area and water is increased while the discharge area remains unchanged, thereby improving the efficiency of plasma water treatment.

[0013] The principle of porous ceramics fixing the liquid surface is to utilize the capillary principle, that is, the interfacial tension between water and ceramics. When the pore size of the porous ceramics is large, the interfacial tension is much smaller than the centrifugal force, and the water in the porous ceramics will shrink inward, and the water will be discharged from the pores of the porous ceramics; due to the hydrophilicity of the ceramics, the porous ceramics will be in a state of no water in the pores, but the material itself is in a wet state. At this time, a water film will also form on the edge of the pore size of the ceramics. In this case, the discharge will only occur preferentially at the place closest to the discharge electrode, that is, the edge of the pore size, rather than uniformly on the water surface.

[0014] When the discharge interval is large, the ratio of the liquid level difference caused by the aperture and the centrifugal force of the rotation speed to the electrode will also change, and the influence of the liquid level difference will be reduced accordingly.

[0015] Based on the above reasons, the preferred discharge distance in the present invention is 5-15 mm, and the pore size of the porous ceramic is 30-120 μm; further preferably: the discharge distance is 5-7 mm, and the pore size of the porous ceramic is 30-60 μm; the discharge distance is 9-15 mm, and the pore size of the porous ceramic is 90-120 μm. Within this range, the contact area between the discharge area and water can be more effectively increased, and the discharge can be uniformly generated on the water surface, thereby improving the efficiency of plasma treatment of water.

[0016] Preferably, the discharge electrode comprises a conductor and a dielectric tube wrapping the conductor.

[0017] Preferably, it comprises a conductor and a dielectric tube wrapping the conductor, the dielectric tube is a three-layer structure, the inner layer is an insulating tube, the middle layer is a polyimide layer wrapped outside the insulating tube, and the outer layer is a PTFE film wrapped outside the polyimide layer, and the surface of the PTFE film in contact with the polyimide layer is an activated surface. The inner layer of the insulating tube is made of ceramic or quartz glass, preferably with a small dielectric constant, and generally controlled to be within 5, the effect will be more ideal. The polyimide layer mainly serves to bond the inner layer and the outer layer.

[0018] Preferably, the insulating tube is a quartz tube, the thickness of the quartz tube is 0.8-1.2 mm, the outer diameter of the tube is 13-17 mm, and the length of the tube is 40-60 mm; more preferably, the thickness of the quartz tube is 1.0 mm, the outer diameter of the tube is 15 mm, and the length of the tube is 50 mm. Preferably, the thickness of the PTFE membrane is about 0.2-0.6 mm, preferably 0.3-0.5 mm, and further 0.5 mm.

[0019] The discharge problem of dielectric barrier discharge has always been an industry problem. Since the discharge must be guaranteed and the safety of the entire system must be guaranteed, the dielectric in the discharge electrode must play a role in protecting and isolating the conductive internal high voltage. However, the current dielectric breakdown resistance and aging resistance are insufficient, and the service life of the electrode is limited. In the present invention, the dielectric tube is designed as a three-layer structure, and the outer structure adopts a single-sided activated PTFE film (polytetrafluoroethylene film). The PTFE coating is not used here because the small bubbles in the coating will greatly reduce the life of the entire material. PTFE is an inert material and is not sticky to almost all materials. In order to ensure the adhesion of the PTFE film to other materials, it is necessary to improve the activity of the PTFE surface and improve the hydrophilicity or lipophilicity of the surface. The general activation method has a chemical method for destroying the surface segments and grafting active groups, such as using a special acid treatment and then grafting hydrophilic groups. Physical methods can also be used, and DBD (dielectric barrier discharge) plasma treatment can achieve similar effects, and the specific activation method can be selected as needed. The middle layer is made of polyimide resin. Polyimide has extremely high temperature resistance and partial discharge resistance. The single-layer activated PTFE can better combine with polyimide without stratification and small bubbles. The inner layer is made of ceramic or quartz glass, and the dielectric constant is preferably small. Generally, the dielectric constant is controlled within 5, and the effect will be more ideal. The dielectric tube of this structure has strong resistance to breakdown and aging, and the service life of the electrode is long. With such a structure, the discharge heating process of the discharge electrode can be greatly reduced. When the internal conductivity is metal + insulating thermal oil (mainly exhausting air to avoid internal discharge) or water, it can prevent the internal liquid temperature from being too high and causing explosions.

[0020] Preferably, the conductor is water, the two ends of the medium tube body are closed and a water inlet is opened in the middle, the water inlet is connected to a water inlet pipe, and the medium tube is suspended in the barrel through the water inlet pipe.

[0021] At present, in the dielectric barrier discharge device, the conductor of the discharge electrode is generally metal, and the insulating medium is generally PTFE or ceramic. However, if it is used as an electrode for a long time, there is a serious heat release problem. The energy utilization rate of DBD dielectric barrier discharge is not high, and most of the energy will be converted into heat energy, so the temperature rise in the discharge area is generally serious. In particular, as a metal electrode wrapped in an insulating medium, due to the poor heat conduction of the insulating medium, the electrode temperature often reaches 200 to 300 degrees, which will cause a series of problems. The biggest problem is that under high temperature conditions, the expansion coefficients of the metal electrode and the insulating medium are different, and the pores introduce air, which will cause discharge inside the high-voltage electrode and affect the life of the electrode. Therefore, in order to avoid this problem, the design replaces the metal electrode with water. Water is conductive, and the fluidity of water is used to transfer heat and cool down. At the same time, the amorphous nature of water can better discharge the air between the conductor and the insulating medium, thereby avoiding the above-mentioned heating problem. Therefore, in the design, the two ends of the dielectric tube are closed with round heads, and a hole is opened in the middle of the dielectric tube to introduce water, and the electrode is suspended, and a certain cycle is used to achieve the purpose of conductivity and cooling.

[0022] Preferably, the dielectric tube adopts a cylindrical structure, and the edge of the dielectric tube is rounded to prevent tip discharge.

[0023] Preferably, a cover is suspended on the top of the barrel, and the cover and the barrel can rotate relative to each other; the discharge electrode is fixed on the side of the cover facing the barrel. The cover can be used to cover the opening at the top of the barrel to prevent the liquid in the barrel from splashing out during rotation; at the same time, the cover is independent of the barrel and does not contact the barrel, so that when the barrel rotates, the cover can remain motionless, thereby ensuring that the discharge electrode installed on the cover remains stationary, avoiding the influence of rotational vibration on the discharge electrode.

[0024] Preferably, a bearing is installed between the cover and the side wall of the drum, and the cover and the side wall of the drum are sealed and rotatably connected through the bearing. The bearing can be provided to seal the gap between the cover and the drum to ensure that liquid does not splash out of the pores when the drum rotates. The bearing is preferably made of rubber, which can effectively reduce the impact of rotational vibration on the cover.

[0025] Due to the effect of gravity, when centrifugal force is generated, if a straight barrel or a structure with a larger bottom and a smaller top is used, water is more likely to accumulate at the bottom, making it difficult to control the appropriate rotation speed to achieve the goal of making the liquid surface parallel to the discharge electrode.

[0026] Based on the above reasons, the present invention preferably has a diameter at the bottom of the barrel that is smaller than the diameter at the top. The barrel is in the shape of an inverted truncated cone, and the diameter at the bottom of the barrel is smaller than the diameter at the top. The barrel adopts a structural design of being larger at the top and smaller at the bottom, so that the water film is more evenly distributed.

[0027] Preferably, the gas-liquid two-phase dielectric barrier discharge device further comprises a spray device, which is suspended in the drum and has a gap with the side wall of the drum, and is used to spray water to the side wall of the drum. The addition of the spray device can more effectively realize the circulation of water and the rotation of the treated water. The small droplets remaining in the air in the area where the spray passes through the air will adsorb the active groups in the air. The efficiency of water treatment is improved. In the scheme in which the gas-liquid two-phase dielectric barrier discharge device is provided with a cover plate, the spray device is installed on the side of the cover body facing the drum.

[0028] The present invention also provides an electrode, comprising a conductor and a dielectric tube wrapping the conductor, wherein the dielectric tube is a three-layer structure, wherein the inner layer is an insulating tube, the middle layer is a polyimide layer wrapped outside the insulating tube, and the outer layer is a PTFE film wrapped outside the polyimide layer, wherein the surface of the PTFE film in contact with the polyimide layer is an activated surface. The dielectric tube of this structure has strong breakdown resistance and aging resistance, and the electrode has a long service life. The electrode can be used as a discharge electrode in a gas-liquid two-phase dielectric barrier discharge device. Preferably, the insulating tube is a quartz tube or a ceramic tube.

[0029] The present invention also provides a method for manufacturing the electrode as described above, wherein the manufacturing of the dielectric tube comprises the following steps:

[0030] Polyimide is coated on the outer wall of the insulating tube, a PTFE film is wrapped on the insulating tube coated with polyimide, the insulating tube wrapped with the PTFE film is placed in a vacuum oven for drying, and then cooled to room temperature; the surface of the PTFE film used to wrap the insulating tube is activated; the drying temperature is 130-220°C, and the time is 2-6 hours.

[0031] Preferably, the insulating tube wrapped with the PTFE film is placed in a vacuum oven, first dried at 120-170°C for 1-2 hours, and then dried at 180-220°C for 2-4 hours. The purpose of drying in the vacuum oven in two stages is to reduce the spatial defects of polyimide and improve the insulation and heat resistance of polyimide. The first stage is the initial curing stage, which is carried out at a relatively low temperature (120-170°C) to control the reaction speed, so that the bonding of polyimide is fixed and the spatial defects are reduced; the second stage is the post-curing stage, which is carried out at a relatively high temperature (180-220°C) to ensure the post-curing reaction, improve the degree of curing of polyimide, and improve the insulation and heat resistance of polyimide.

[0032] Preferably, the insulating tube wrapped with the PTFE film is placed in a vacuum oven, first dried at 150° C. for 1 hour, and then dried at 200° C. for 3 hours.

[0033] Compared with the prior art, the gas-liquid two-phase dielectric barrier discharge device provided by the present invention adopts the outer wall rotation method, utilizes centrifugal force to realize static non-aqueous electrode and dynamic water electrode, and at the same time, in order to solve the situation that the liquid surface has certain fluctuations under the rotation condition, it also increases the discharge water phase contact surface. The rotating outer wall material is changed to a porous ceramic material, and the porous characteristics of the ceramic are utilized to relatively increase the liquid phase surface. The viscosity of the liquid surface will drive the air above the liquid surface to flow. The utilization efficiency of the plasma in this area is further improved. To further improve the efficiency, the internal liquid adopts a circulating spraying method. The porous ceramic area where the nozzle is aimed, due to the existence of centrifugal force, most of the water will be evenly distributed on the porous ceramic surface and the inner surface of the hole; part of the liquid is in the dispersed gas phase, further absorbing the active components in the water air. The discharge electrode adopts a cylindrical structure, and the edge part is rounded to prevent tip discharge. The dielectric layer adopts a three-layer structure, with PTFE as the outer layer, polyimide as the middle layer, and ceramic as the inner layer. The three-layer composite dielectric jointly solves the problems of heat release, breakdown, and electrode aging caused by internal discharge due to temperature rise.

[0034] The above technical features can be combined in various suitable ways or replaced by equivalent technical features as long as the purpose of the present invention can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention will be described in more detail below based on non-limiting examples and with reference to the accompanying drawings, in which:

[0036] Figure 1 A schematic diagram of the electrode structure of a conventional dielectric barrier discharge;

[0037] Figure 2 A schematic structural diagram of a gas-liquid two-phase dielectric barrier discharge device provided in one embodiment of the present invention;

[0038] Figure 3 A schematic cross-sectional view of the assembly of a ceramic ring and a side wall of a drum provided in one embodiment of the present invention.

[0039] Description of reference numerals:

[0040] 1. Cover; 2. Drum; 3. Discharge electrode; 4. Bearing; 5. Spraying device; 6. Chassis; 7. Water inlet pipe; 8. Ceramic ring; 9. Groove; 21. Side wall; 31. Dielectric pipe; 100. AC high voltage power supply; 200. High voltage electrode; 300. Dielectric layer; 400. Grounding electrode. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Based on the specific implementation methods in the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0042] The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. The words "include" or "comprise" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0043] In the present disclosure, when a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other device without an intermediate device, or may not be directly connected to the other device but have an intermediate device.

[0044] All terms (including technical terms or scientific terms) used in the present disclosure have the same meanings as those understood by ordinary technicians in the field to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, such as general dictionaries, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0045] When using dielectric barrier discharge to treat water or produce plasma-activated water, the most effective way is to use the water phase to be treated or activated as an electrode. At that time, the plasma generation area will have the largest area of ​​contact with the water phase, and the water phase treatment effect will be optimal.

[0046] Figure 1 A conventional dielectric barrier discharge electrode structure is shown. The structure of the liquid two-phase dielectric barrier discharge device provided by the present invention mainly utilizes the following Figure 1 The structural principle shown is that the discharge structure is a "conductor | dielectric - air - conductor" structure, where "conductor | dielectric" refers to a structure in which the conductor and the insulating dielectric layer are seamlessly combined into one. If there is air in the gap between the conductor and the dielectric, this part of the air may be broken down during dielectric barrier discharge.

[0047] In general, the air gap is generally less than 10mm to ensure the discharge voltage, power consumption and other effects, and is generally controlled at 2mm to 7mm for a stable effect. The smaller the gap, the lower the starting voltage and the easier it is to stabilize the discharge. However, due to the amorphous nature of water, external disturbances can easily cause horizontal plane fluctuations. When parallel discharge is performed using electrodes parallel to the water surface, this water disturbance can cause unstable discharge. If the water surface tilts and part of the conductive discharge electrode enters the water, the discharge will be terminated, or a higher voltage will be required (water will produce surface discharge on the dielectric surface of the other electrode). Therefore, similar devices have always been balancing the stability of the water surface and the electrode gap. Even so, such devices have relatively strict requirements for use conditions.

[0048] like Figure 2 As shown, the gas-liquid two-phase dielectric barrier discharge device mainly includes a barrel 2, a discharge electrode 3 and a spray device 5. The barrel 2 is closed at the bottom and open at the top. The barrel 2 can rotate around its axis under the drive of the driving device. The discharge electrode 3 and the spray device 5 are suspended in the barrel 2 and a gap is left between the inner surface of the side wall of the barrel 2; the spray device 5 is used to spray water to the side wall 21 of the barrel 2, and the water film formed on the side wall 21 of the barrel 2 serves as a water electrode. The angle between the discharge electrode 3 and the axis of the barrel 2 is equal to the angle between the side wall 21 of the barrel 2 and its axis. The discharge electrode 3 is parallel to the side wall 21 of the barrel 2, thereby ensuring that the discharge electrode 3 is parallel to the surface of the water electrode.

[0049] By rotating, centrifugal force is used to ensure that the liquid surface and the discharge electrode 3 are parallel and stable. At the same time, the surface viscosity of the outer wall is used to drive the air flow, thereby improving the utilization efficiency of the active plasma in the discharge area. At least one discharge electrode 3 is arranged in the barrel 2, but in order to further increase the contact area between the discharge area and water, multiple discharge electrodes 3 can also be arranged in the barrel 2 at intervals.

[0050] The spray device 5 is used to replenish water to the side wall 21 of the barrel 2. First, it is beneficial for replacing the liquid phase surface of the water electrode; second, it increases the amount of droplets in the air and more efficiently utilizes the active components in the air. Third, it keeps the liquid phase of the side wall 21 of the barrel 2 stable. The spray device 5 is preferably set in the opposite direction of the discharge electrode 3 to avoid the water droplets affecting the dielectric barrier discharge. When the water sprayed by the spray device 5 on the side wall of the barrel 2 reaches the discharge area after half a circle of rotation, there should be no obvious water flow. Preferably, the spray device 5 can form a more uniform atomization, which is convenient for small water droplets to effectively adsorb active groups in the air.

[0051] Due to the effect of gravity, when centrifugal force is generated, water is more likely to accumulate at the bottom of the barrel 2 if a straight barrel or a structure with a larger bottom and a smaller top is used, and it is difficult to control a suitable rotation speed to achieve the purpose of the liquid surface being parallel to the discharge electrode 3. In the present invention, the barrel 2 is preferably in an inverted truncated cone shape as a whole, the diameter of the bottom of the barrel 2 is smaller than the diameter of the top, and the barrel 2 adopts a structure design with a larger top and a smaller bottom, so that the water film is more evenly distributed.

[0052] like Figure 3 As shown, an annular groove 9 is provided on the inner side wall 21 of the drum 2, and a ceramic ring 8 made of porous ceramic is embedded in the annular groove 9. A gap is left between the discharge electrode 3 and the side wall 21 of the ceramic ring 8, and the angle between the discharge electrode 3 and the axis of the ceramic ring 8 is equal to the angle between the side wall 21 of the ceramic ring 8 and its axis; the spray device 5 is used to spray water to the inner wall of the ceramic ring 8 to form a water film on the surface of the ceramic ring 8. The thickness of the ceramic ring 8 is greater than the depth of the annular groove 9, so as to ensure that the ceramic ring 8 protrudes from the side wall 21 of the drum 2, thereby ensuring that the liquid surface on the ceramic ring 8 is closer to the discharge electrode 3 than the liquid surface on the side wall 21 of the drum 2, so that the discharge is more concentrated on the porous ceramic surface.

[0053] In one embodiment, the lower bottom radius of the barrel 2 is 150mm, the upper bottom radius is 200mm, and the height of the barrel 2 is 200mm; the side wall of the barrel 2 is made of PC material as a whole, the side wall thickness is about 10mm, and a groove 9 with a length of about 70mm, a width of about 70mm and a depth of 5mm is finely processed at a distance of about 70mm from the bottom surface of the barrel 2; the porous ceramic ring 8 is embedded in the groove 9, the thickness of the porous ceramic ring 8 is about 8mm, and it is about 3mm higher than the groove 9.

[0054] The pore size of porous ceramics should be neither too large nor too small. When it is too large, due to the effect of centrifugal force, the discharge only acts on the water surface of the protruding part. When it is too small, the centrifugal force is not enough to press the water film into a state where the water film is inside the hole, and the purpose of increasing the discharge area cannot be achieved. The pore size is also related to the centrifugal force and the discharge spacing. When the discharge spacing is large, the pore size can be slightly larger. In the present invention, it is preferred that the discharge distance is 5 to 15 mm, and the pore size of the porous ceramic is 30 to 120 μm; further preferably: the discharge distance is 5 to 7 mm, and the pore size of the porous ceramic is 30 to 60 μm; the discharge distance is 9 to 15 mm, and the pore size of the porous ceramic is 90 to 120 μm. Within this range, the contact area between the discharge area and the water can be more effectively increased, and the discharge can be evenly generated on the water surface, thereby improving the efficiency of plasma treatment of water.

[0055] The discharge electrode 3 includes a conductor and a dielectric tube 31 that wraps the conductor. The dielectric tube 31 adopts a cylindrical structure, and the edge of the dielectric tube 31 is rounded to prevent tip discharge. The dielectric tube 31 is a three-layer structure, the inner layer is made of an insulating material, and a quartz tube or a ceramic tube can be used. In this embodiment, the inner layer of the dielectric tube 31 is preferably a quartz tube made of quartz glass; the middle layer is a polyimide layer wrapped outside the quartz tube, and the polyimide mainly plays a bonding role and has extremely high temperature resistance and partial discharge resistance; the outer layer is a PTFE film (polytetrafluoroethylene film) wrapped outside the polyimide layer, and the surface where the PTFE film contacts the polyimide layer is an activated surface. The single-layer activated PTFE can better combine with polyimide without stratification and small bubbles. The conductor is water. Both ends of the medium tube 31 are closed and a water inlet is opened in the middle. The water inlet is connected to the water inlet pipe 7. The medium tube 31 is suspended in the barrel 2 through the water inlet pipe 7. The fluidity of water can be used to fill the medium tube 31 with water, and the gas in the medium tube 31 is discharged to avoid discharge inside the high-voltage electrode, which is beneficial to prolonging the life of the electrode.

[0056] Taking the inner insulating tube as a quartz tube as an example, the preparation of the dielectric tube 31 includes the following steps:

[0057] Polyimide is coated on the outer wall of the quartz tube, and a single-sided activated PTFE film is wrapped on the quartz tube coated with polyimide. The surface of the PTFE film used to wrap the quartz tube is activated, and the quartz tube wrapped with the PTFE film is placed in a vacuum oven for drying, and then cooled to room temperature to obtain a medium tube 31.

[0058] The thickness of the PTFE membrane is about 0.5mm. The PTFE membrane is pre-made into a bagged structure, and the inner surface is pre-activated to facilitate the bonding of polyimide. The activation method includes chemical methods such as destroying the surface segments and grafting active groups, such as using special acid treatment and then grafting hydrophilic groups. Physical methods can also be used, such as DBD (dielectric barrier discharge) plasma treatment to achieve similar effects. The specific activation method can be selected according to needs.

[0059] Preferably, the drying treatment is carried out in two steps: the first step is drying at 120-170°C for 1-2 hours, more preferably, the drying temperature is 150°C and the time is 1 hour; the second step is drying at 180-220°C for 2-4 hours, more preferably, the drying temperature is 200°C and the time is 3 hours.

[0060] In order to prevent liquid from splashing out when the barrel 2 rotates, it is preferred to add a cover 1, which can be suspended on the top of the barrel 2 using a bracket or a fixed platform to ensure that there is a gap between the cover 1 and the barrel 2, so that the cover 1 can remain stationary when the barrel 2 rotates. The cover 1 can be used to cover the opening at the top of the barrel 2 to prevent the liquid in the barrel 2 from splashing out when rotating; at the same time, the cover 1 is independent of the barrel 2 and does not contact the barrel 2, so that when the barrel 2 rotates, the cover 1 can remain stationary, thereby ensuring that the discharge electrode 3 and the spray device 5 installed on the cover 1 remain stationary, avoiding the influence of rotational vibration on the discharge electrode 3 and the spray device 5. The discharge electrode 3 and the spray device 5 are fixed on the side of the cover 1 facing the barrel 2.

[0061] A bearing 4 may also be installed between the cover 1 and the side wall 21 of the barrel 2, and the cover 1 and the side wall 21 of the barrel 2 are sealed and rotatably connected through the bearing 4. The bearing 4 can be provided to seal the gap between the cover 1 and the barrel 2 to ensure that liquid does not splash out of the pores when the barrel 2 rotates. The bearing 4 is preferably made of rubber, which can effectively reduce the impact of rotational vibration on the cover 1, the discharge electrode 3 and the spray device 5. The barrel 2, the cover 1 and the chassis 6 can all be made of PC material.

[0062] In order to facilitate the rotation of the barrel 2, a chassis 6 can be fixedly installed at the bottom of the barrel 2, and a motor is installed at the center of the bottom of the chassis 6. It is required that the barrel 2 coincides with the center of the motor shaft, and the motor can drive the chassis 6 to rotate, and then the chassis 6 drives the barrel 2 to rotate around the axis of the barrel 2. For example, when the motor is 180R / min, the eccentric distance of the porous ceramic segment does not exceed 1mm, and it can be considered that the barrel 2 coincides with the center of the motor shaft.

[0063] When using a gas-liquid two-phase dielectric barrier discharge device for water treatment, the following steps are included:

[0064] 1. Add an appropriate amount of water into the barrel 2. The amount of water added should be such that the water cannot contact the discharge electrode 3;

[0065] 2. Turn on the motor at the bottom of the chassis 6 to rotate the entire barrel 2;

[0066] 3. Turn on the spray device 5 to spray atomized water on the porous ceramics of the side wall. The spray device 5 adopts internal water circulation;

[0067] 4. Turn on the voltage of the amplifying electrode, and the water inside the discharge electrode 3 is grounded through the wire;

[0068] 5. The discharge electrode 3 and the water surface of the side wall form a dielectric barrier discharge structure. When the voltage and frequency are appropriate, the high-voltage electrode and the side wall generate plasma discharge to treat the water or produce activated water.

[0069] In the gas-liquid two-phase dielectric barrier discharge device, the electrodes and the spray device 5 remain stationary, and the side walls rotate with the bottom plate 6, which produces the effect that the water in the area where the plasma discharge is performed is constantly replaced.

[0070] Finally, it should be noted that the above implementation modes and examples are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above implementation modes and examples, those skilled in the art should understand that they can still modify the technical solutions described in the above implementation modes or examples, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the implementation modes or examples of the present invention.

Claims

1. A gas-liquid two-phase dielectric barrier discharge device, characterized in that: It comprises a drum and a discharge electrode; the drum can rotate around its axis; the discharge electrode is suspended in the drum and a gap is left between the side wall of the drum; the angle between the discharge electrode and the axis of the drum is equal to the angle between the side wall of the drum and its axis; The side wall of the drum is made of porous ceramics or a ceramic ring made of porous ceramics is arranged on the inner surface of the side wall of the drum; a gap is left between the discharge electrode and the ceramic ring, and the angle between the discharge electrode and the axis of the ceramic ring is equal to the angle between the inner wall of the ceramic ring and its axis; The diameter of the bottom of the barrel is smaller than the diameter of the top; The discharge electrode comprises a conductor and a dielectric tube wrapping the conductor; The dielectric tube has a three-layer structure, wherein the inner layer is an insulating tube, the middle layer is a polyimide layer wrapped outside the insulating tube, and the outer layer is a PTFE film wrapped outside the polyimide layer, and the surface of the PTFE film in contact with the polyimide layer is an activated surface; The dielectric tube is a cylindrical structure, and the edge of the dielectric tube is rounded to prevent tip discharge.

2. The gas-liquid two-phase dielectric barrier discharge device according to claim 1, characterized in that: The discharge distance is 5 to 15 mm, and the pore size of the porous ceramic is 30 to 120 μm.

3. The gas-liquid two-phase dielectric barrier discharge device according to claim 2, characterized in that: The discharge distance is 5-7 mm, and the pore size of the porous ceramic is 30-60 μm.

4. The gas-liquid two-phase dielectric barrier discharge device according to claim 2, characterized in that: The discharge distance is 9-15 mm, and the pore size of the porous ceramic is 90-120 μm.

5. The gas-liquid two-phase dielectric barrier discharge device according to claim 1, characterized in that: The ceramic ring is convexly arranged on the inner wall of the barrel.

6. The gas-liquid two-phase dielectric barrier discharge device according to claim 5, characterized in that: The insulating tube is a quartz tube, the thickness of the quartz tube is 0.8-1.2 mm, the outer diameter of the tube is 13-17 mm, and the length of the tube is 40-60 mm.

7. The gas-liquid two-phase dielectric barrier discharge device according to claim 6, characterized in that: The thickness of the quartz tube is 1.0 mm, the outer diameter of the tube is 15 mm, and the length of the tube is 50 mm.

8. The gas-liquid two-phase dielectric barrier discharge device according to claim 5, characterized in that: The thickness of the PTFE film is 0.2-0.6 mm.

9. The gas-liquid two-phase dielectric barrier discharge device according to claim 5, characterized in that: The thickness of the PTFE film is 0.5 mm.

10. The gas-liquid two-phase dielectric barrier discharge device according to claim 4, characterized in that: The conductor is water. Both ends of the medium tube body are closed and a water inlet is opened in the middle. The water inlet is connected to a water inlet pipe. The medium tube is suspended in the barrel through the water inlet pipe.

11. The gas-liquid two-phase dielectric barrier discharge device according to claim 1, characterized in that: A cover is suspended on the top of the barrel, and the cover and the barrel can rotate relative to each other; the discharge electrode is fixed on the side of the cover facing the barrel.

12. The gas-liquid two-phase dielectric barrier discharge device according to claim 11, characterized in that: A bearing is installed between the cover body and the inner wall of the barrel, and the cover body and the inner wall of the barrel are sealed and rotatably connected through the bearing.

13. The gas-liquid two-phase dielectric barrier discharge device according to claim 1, characterized in that: It also includes a spray device, which is suspended in the barrel with a gap between the spray device and the side wall of the barrel, and is used to spray water to the side wall of the barrel.

14. An electrode, characterized in that: It comprises a conductor and a dielectric tube wrapping the conductor, wherein the dielectric tube is a three-layer structure, wherein the inner layer is an insulating tube, the middle layer is a polyimide layer wrapped outside the insulating tube, and the outer layer is a PTFE film wrapped outside the polyimide layer, and the surface of the PTFE film in contact with the polyimide layer is an activated surface.

15. The electrode according to claim 14, characterized in that The insulating tube is a quartz tube or a ceramic tube.

16. A method for manufacturing an electrode as claimed in claim 14 or 15, characterized in that: The production of the medium tube includes the following steps: Polyimide is coated on the outer wall of the insulating tube, a PTFE film is wrapped on the insulating tube coated with polyimide, the quartz tube wrapped with the PTFE film is placed in a vacuum oven for drying, and then cooled to room temperature to obtain a dielectric tube; the surface of the PTFE film used to wrap the insulating tube is activated; the drying temperature is 130-220°C, and the time is 2-6 hours.

17. The method for manufacturing an electrode according to claim 16, characterized in that: The insulating tube wrapped with the PTFE film is placed in a vacuum oven, first dried at 120-170°C for 1-2 hours, and then dried at 180-220°C for 2-4 hours.

18. The method for preparing an electrode according to claim 17, characterized in that: The insulating tube wrapped with the PTFE film was placed in a vacuum oven, first dried at 150°C for 1 hour, and then dried at 200°C for 3 hours.

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