CN101835336A - A Double Dielectric Barrier Discharge Low Temperature Plasma Generator - Google Patents

Abstract

The invention discloses a double-dielectric barrier discharge low-temperature plasma device, and belongs to the field of low-temperature plasma technology. The plasma device comprises an air inlet (1), a polytetrafluoroethylene plug (2), a low voltage electrode (3), a quartz glass tube A (4), a quartz glass tube B (5), a high voltage electrode (6) and an air outlet (7), wherein the outer layer of the high voltage electrode (6) is the quartz glass tube B (5), and the low voltage electrode (3) consists of constantan sheets and is led out by a lead wire and grounded. In the process of treating pollutant gas, the low-temperature plasma generator can effectively reduce the corrosion of air on the high voltage electrode and avoid generating arc discharge and further damaging or breaking down discharge dielectric layers. The formed double-dielectric barrier discharge has high stability and high energy density utilization rate. The low-temperature plasma device can stably work under normal pressure and is applied to the discharge of automotive noxious pollutant gas.

Description

A Double Dielectric Barrier Discharge Low Temperature Plasma Generator

technical field

The invention belongs to the technical field of low-temperature plasma, and more precisely relates to a double dielectric barrier discharge low-temperature plasma generator.

Background technique

Dielectric barrier discharge (DBD) is a non-equilibrium gas discharge in which a dielectric layer is placed in the discharge space. In the DBD structure, at least one layer of dielectric covers the electrodes or hangs in the discharge space; in this way, when an AC voltage of a certain frequency (50Hz-1MHz) is applied between the two electrodes, the gas between the electrodes will be broken down to form a dielectric barrier discharge. The insulating properties of the dielectric layer make the surface approximately uniformly distributed small "local capacitance" on the microscopic level, which makes the insulating medium have two functions: one is to limit the movement of charged particles in micro-discharge, that is, to limit the free growth of current density , so that the micro-discharge becomes a short pulse; the second is to prevent partial spark discharge or arc discharge, and to form a stable gas discharge under normal atmospheric pressure. DBD plasma can be carried out under normal pressure environment, the cost is extremely low, the adaptability is strong, only AC power supply can meet the production requirements, the equipment is simple, and it has potential development space and great application value in the field of gas pollutant treatment .

Chinese patent CN1404349 provides a low-temperature plasma generator. The generator is composed of a ceramic tube, an anode wound by nickel-chromium wire, a cathode wound by copper plate and a cooling block. The ceramic tube is fired with silicate material, and the anode wound by nickel-chromium wire is installed on the inner wall of the ceramic tube. The cathode made of copper plate is attached to the outer wall of the ceramic tube, and the high temperature heat-resistant heat dissipation paint is poured on the outside of the copper plate electrode, and the ceramic tube is installed in the heat dissipation block. The plasma generator with this structure has high energy density and is mainly used for wastewater and water source purification treatment. Chinese patent CN1126939 provides a low-temperature plasma generator. In this generator, a rod-shaped conductor is inserted into a through hole provided in the longitudinal direction of a rod-shaped ceramic dielectric, and the two ends of the conductor and the dielectric are bonded together with a glass, inorganic or organic adhesive, and sealed to form an electrode. This kind of generator can be discharged in dry air, high humidity air or water, and is mainly used in deodorization, sterilization, water purification, etc., but it has shortcomings in the treatment of high-temperature waste gas. Chinese patent CN1421564 provides a dielectric barrier discharge continuous treatment device for surface modification of fiber materials. The device consists of a power supply system, mainly including a pair of coolable planar discharge electrodes and a plasma generator and processor composed of two dielectric barrier plates placed between the electrodes, a gas supply system, a coolant circulation cooling system, and a Composition of material transfer winding system. The flat electrode dielectric barrier discharge is used to generate uniform low-temperature plasma under atmospheric pressure, which can avoid arcing and spark discharge between electrodes, and effectively carry out continuous surface modification treatment on fiber materials. This device is mainly used for surface modification of materials, and is not suitable for processing harmful gas pollutants.

The low-temperature plasma system contains a large number of active species such as high-energy electrons, ions, excited particles, and strong oxidizing free radicals. During the gas-phase chemical reaction, these active substrates can chemically react with pollutants such as CO, HC, NO _x and PM, and convert them into harmless or low-harm gases. Most of the currently designed low-temperature plasma generators are suitable for industrial sterilization, air purification and wastewater treatment. For automobile gas pollutant emissions, due to the complex gas composition, high temperature and corrosiveness. Therefore, using a plasma generator to treat gas pollutant emissions from automobiles requires ensuring the tightness of the generator and the corrosion resistance of the electrodes to ensure the stable operation of the generator.

Contents of the invention

What the present invention aims to solve is to effectively enhance the energy density of the plasma, and avoid the problems of harmful gases causing corrosion to the high-voltage electrodes. It provides a double dielectric barrier discharge low-temperature plasma generator, which can effectively enhance the electron density in the plasma gas-phase chemical reaction zone. The energy density is high, and the discharge is stable; the harmful gas flows between the two media, which effectively avoids contact with the high-voltage electrode and causes corrosion.

The technical solution adopted in the present invention is: the outer layer of the high-voltage electrode in the low-temperature plasma discharge area is covered with a quartz glass tube, which is used to prevent the harmful gas from directly contacting the high-voltage electrode during the pollutant treatment process, and causing corrosion to it at high temperature; The double dielectric barrier discharge structure can avoid arc discharge and protect the dielectric layer, thus ensuring the stability of discharge. In addition, the energy is evenly distributed in the plasma gas phase reaction area, which is beneficial to improve the conversion efficiency of pollutant treatment. This structure ensures the high-efficiency and stable operation of the low-temperature plasma generator, and avoids the harmful gas from corroding the high-voltage electrodes.

The specific technical scheme of the present invention is that it includes a shell, an air inlet, a polytetrafluoroethylene plug, a low-voltage electrode, a high-voltage electrode and an exhaust port; The head is plugged at both ends of the quartz glass tube shell, and the tube walls at both ends of the quartz glass tube shell are respectively provided with an air inlet and an exhaust port. The axis of the air inlet is parallel to the axis of the exhaust port and on the same plane. The opening of the gas port is opposite to the opening direction of the exhaust port; the high-voltage electrode is set in the center of the quartz glass tube shell, and the two ends of the high-voltage electrode pass through two PTFE plugs respectively; the low-voltage electrode is a round tube, wrapped in The outside of the tube wall of the quartz glass tube shell. The low-voltage electrode is a constantan electrode, which is grounded after being drawn out through a lead wire.

The outer layer of the high-voltage electrode is covered with a quartz glass tube, and the axial length of the quartz glass tube is greater than that of the circular tubular low-voltage electrode.

The beneficial effect of the invention is that the double dielectric barrier discharge structure makes the discharge more stable, and the energy density is more evenly distributed in the plasma gas phase reaction area, which is beneficial to improving the conversion efficiency of pollutants. In addition, in the process of treating pollutants, direct contact between harmful gases and high-voltage electrodes can be effectively avoided, ensuring the stability of discharge. This structure is not only suitable for industrial waste gas purification, but also suitable for experimental research on the treatment of automobile gas pollutant emissions.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic diagram of an axial sectional structure of a generator of the present invention.

Fig. 2 is a schematic perspective view of the generator of the present invention.

Fig. 3 is a schematic diagram of the structure of the high voltage electrode of the present invention.

In the figure, 1. Air inlet; 2. Teflon plug; 3. Low voltage electrode; 4. Quartz glass tube A; 5. Quartz glass tube B; 6. High voltage electrode; 7. Exhaust port.

Detailed ways

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

The dual-dielectric barrier discharge low-temperature plasma device of the present invention connects the high-voltage electrode 6 to a variable-voltage variable-frequency plasma power supply and the low-voltage electrode 3 to ground to generate low-temperature plasma discharge between the two dielectrics. The outer layer of the high-voltage electrode 6 is covered with a quartz glass tube B5, which can prevent the harmful gas from corroding the electrode during the discharge process, protect the discharge performance of the electrode, make the work of the low-temperature plasma generator more stable, and effectively extend the life. The present invention adopts a double-dielectric barrier discharge structure, and the gas enters the gas phase reaction zone of the low-temperature plasma generator through the gas inlet 1 and is discharged from the exhaust port 7. The uniform and strong discharge of this structure can enhance the plasma energy density, so that the gas components can Enough electron energy is obtained, thereby improving the conversion efficiency of gas components. The overall structure adopts the quartz glass tube A4 shell, which is conducive to the visual observation of the dielectric barrier discharge morphology and the discharge process during the test process, and the economy is relatively good.

Claims (3)

1. a double dielectric barrier discharge low-temperature plasma generator, is characterized in that, comprises shell, air inlet (1), polytetrafluoroethylene plug (2), low voltage electrode (3), high voltage electrode (6) and Exhaust port (7); the shell is a round tube-shaped quartz glass tube A (4), and two polytetrafluoroethylene plugs (2) are plugged into the two ends of the shell of the quartz glass tube A (4) , the pipe wall at both ends of the quartz glass tube A (4) is respectively provided with an air inlet (1) and an air outlet (7), the axis of the air inlet (1) and the axis of the air outlet (7) Parallel and on the same plane, the opening of the air inlet (1) is opposite to the opening direction of the exhaust port (7); the high voltage electrode (6) is placed in the quartz glass tube A (4), and the high voltage electrode (6) The two ends of each pass through two polytetrafluoroethylene plugs (2); the low-voltage electrode (3) is in the shape of a round tube, wrapped on the outside of the tube wall of the quartz glass tube A (4), and grounded through a lead wire. 2. A kind of double-dielectric barrier discharge low-temperature plasma generator according to claim 1, characterized in that, the outer layer of the high-voltage electrode (6) is covered with a quartz glass tube B (5), and the quartz glass tube B (5) The axial length of B (5) is greater than the axial length of the circular tubular low voltage electrode (3). 3. A low-temperature plasma generator with double dielectric barrier discharge according to claim 1, characterized in that the low-voltage electrode (3) is a constantan electrode.

Images