Flow-type dielectric barrier discharge device

Abstract

A runoff dielectric barrier discharge device includes a housing (1), a fluid channel (2) inside the housing (1), a first discharge electrode (3) and a second discharge electrode (4) made of conductive material inside the fluid channel (2), and a barrier medium (5) made of insulating material between the first discharge electrode (3) and the second discharge electrode (4). The barrier medium (5) is a plate that is permeable to fluid, and the plate surface of the barrier medium (5) is arranged along the direction that can block the fluid channel (2). Its purpose is to provide a runoff dielectric barrier discharge device that can handle a large volume of fluid, has a good treatment effect, stable working performance, long service life, and can more efficiently treat nitrogen oxides in flue gas, promoting ammonia to convert nitrogen oxides in flue gas into nitrogen and water.

Description

Technical Field

[0001] This invention relates to a radial flow dielectric barrier discharge device. Background Technology

[0002] Dielectric barrier discharge (DBD) is a non-equilibrium gas discharge in which an insulating dielectric is inserted into the discharge space; it is also known as dielectric barrier corona discharge or silent discharge. DBD can operate at high pressures and over a wide frequency range, typically from 10 to 10,000 rpm. The power supply frequency can range from 50 Hz to 1 MHz.

[0003] Dielectric barrier discharge (DBD) involves filling the space between two discharge electrodes with a working gas and covering one or both electrodes with an insulating dielectric, or suspending the dielectric directly in the discharge space. When a sufficiently high AC voltage is applied between the electrodes, the gas between them breaks down, generating a discharge, which is called dielectric barrier discharge. Dielectric barrier discharge can be used to remove recalcitrant substances from waste gases.

[0004] Dielectric barrier discharge with a planar electrode structure is also widely used in the modification, grafting, surface tension enhancement, cleaning, and hydrophilic modification of polymer and metal films and sheets in industry.

[0005] Dielectric barrier discharge generates a large number of free radicals and quasi-molecules, such as OH, O, and NO, during the discharge process. These are chemically highly reactive and readily react with other atoms, molecules, or other free radicals to form stable atoms or molecules. Therefore, the properties of these free radicals can be utilized to treat VOCs, which has significant value in environmental protection. Furthermore, dielectric barrier discharge can be used to create quasi-molecular radiation sources that emit narrowband radiation covering the infrared, ultraviolet, and visible light spectral regions without self-absorption. It is a high-efficiency, high-intensity monochromatic light source. In the dielectric barrier discharge electrode structure, a pipeline electrode structure can also be used to create an ozone (O3) generator.

[0006] The specific technical solution of the Chinese patent application number CN201410773469.9, entitled "Nitrogen oxide removal device and method based on dielectric barrier discharge reactor", is as follows:

[0007] A nitrogen oxide removal device based on a dielectric barrier discharge reactor includes a flue gas desulfurization reactor, an ammonia injection system, a dielectric barrier discharge reactor, a mixed gas reactor, and a flue gas chamber. The outlets of the flue gas desulfurization reactor and the ammonia injection system are connected to the inlet of the dielectric barrier discharge reactor. The outlet of the dielectric barrier discharge reactor is connected to the inlet of the mixed gas reactor, and the outlet of the mixed gas reactor is connected to the flue gas chamber.

[0008] The dielectric barrier discharge reactor includes a high-frequency high-voltage power supply, an insulating shell, and at least one module disposed within the insulating shell. The module includes two parallel insulating dielectric plates and a dielectric layer plate disposed between the two insulating dielectric plates. The dielectric layer plate is parallel to the insulating dielectric plates and has a metal coating on its outer surface.

[0009] Two parallel insulating dielectric plates are connected to the positive and negative terminals of a high-frequency high-voltage power supply, respectively. Each insulating dielectric plate contains metal electrodes arranged at equal intervals, and the metal electrodes are connected in parallel by wires.

[0010] The dielectric layer is a mesh structure made of insulating dielectric, which is about the same size as the insulating dielectric plate and has a thickness of no more than 2 mm. It is fixedly placed between two insulating dielectric plates at equal intervals and fixedly connected to the insulating shell.

[0011] The insulating dielectric plate has dimensions of 500mm–1000mm × 500mm–1000mm and a thickness of 30mm–50mm; the metal electrode has a diameter of 25mm–45mm and a length of 400mm–900mm. The specific dimensions of the insulating dielectric plate depend on the specific operating conditions; the ranges given above include dimensions required for both small-scale experiments and large-scale industrial applications. The diameter and length of the metal electrode are determined based on the thickness and length of the insulating dielectric plate; the diameter of the metal electrode is slightly smaller than the thickness of the insulating dielectric plate, and the length is slightly smaller than the length of the insulating dielectric plate.

[0012] To prevent the metal electrodes from interfering with each other due to too small gaps and to ensure uniform discharge in the dielectric barrier discharge reactor, it is preferable to embed 10 to 20 metal electrodes inside each insulating dielectric plate, with a gap of 50 mm to 100 mm.

[0013] To achieve maximum effective discharge, the preferred spacing between the two insulating dielectric plates is 2mm to 500mm.

[0014] The purpose of this invention is to address the problems of short catalyst activity time and narrow operating temperature window in existing SCR denitrification technologies. The novel denitrification technology proposed in this invention primarily utilizes a dielectric barrier discharge reactor to replace the catalyst in existing SCR technologies. The dielectric barrier discharge reactor can generate low-temperature plasma at room temperature through high-frequency, high-voltage power discharge. Free electrons, ions, and active groups in the plasma bombard the metal coating in the dielectric barrier discharge reactor. The metal loses electrons to generate metal ions, which have a strong pre-activation function, prompting ammonia to convert nitrogen oxides in the flue gas into nitrogen and water.

[0015] However, the existing technology has the following problems during operation: Since the flue gas to be treated flows between two parallel insulating dielectric plates along the plate surfaces, while the discharge occurs between these two parallel insulating dielectric plates in a direction perpendicular to the fluid flow direction, the contact and mixing of the flue gas with the low-temperature plasma generated by the high-frequency, high-voltage power supply is very uneven. Near the surfaces of the two insulating dielectric plates, more low-temperature plasma is mixed in, leading to a more thorough conversion of nitrogen oxides in the flue gas into nitrogen and water. Conversely, in the flue gas farther from the surfaces of the two insulating dielectric plates, only a small amount of low-temperature plasma is mixed in, preventing a significant amount of nitrogen oxides from being converted into nitrogen and water. Due to these problems, the existing nitrogen oxide removal devices based on dielectric barrier discharge reactors are not very effective in converting nitrogen oxides in flue gas into nitrogen and water using ammonia.

[0016] Furthermore, existing dielectric barrier discharge devices generate a significant amount of heat during operation. Due to inadequate heat dissipation, the first and second discharge electrodes of the device experience substantial temperature increases after a period of operation, resulting in a short lifespan for both electrodes. Additionally, the insulating dielectric plate, being a non-fluid-permeable structure, also severely impacts the flow rate of the flue gas being treated. Summary of the Invention

[0017] The purpose of this invention is to provide a run-of-flow dielectric barrier discharge device that can handle large fluid volumes, has good treatment effects, stable working performance, long service life, and can more efficiently treat nitrogen oxides in flue gas, promoting ammonia to convert nitrogen oxides in flue gas into nitrogen and water.

[0018] The present invention provides a flow-type dielectric barrier discharge device, which includes a housing, a fluid channel inside the housing, a first discharge electrode and a second discharge electrode made of conductive material inside the fluid channel, and a barrier medium made of insulating material between the first discharge electrode and the second discharge electrode. The barrier medium is a plate that is permeable to fluid, and the plate surface of the barrier medium is arranged along the direction that can block the fluid channel.

[0019] Preferably, the first discharge electrode and / or the second discharge electrode are plate-shaped with fluid-permeable surfaces, and the surfaces of the first discharge electrode and / or the second discharge electrode are arranged along a direction that can block the fluid channel.

[0020] Preferably, a third discharge electrode made of conductive material is provided behind the second discharge electrode. The third discharge electrode is plate-shaped with a fluid-permeable surface. The surface of the third discharge electrode is arranged along the direction that can block the fluid channel. A second blocking medium made of insulating material is provided between the second discharge electrode and the third discharge electrode. The second blocking medium is plate-shaped with a fluid-permeable surface. The surface of the second blocking medium is arranged along the direction that can block the fluid channel.

[0021] Preferably, the barrier medium and the second barrier medium are microporous ceramics or organic porous foam materials that can filter fluids.

[0022] Preferably, the first discharge electrode, the second discharge electrode, and the third discharge electrode are made of foam metal plate, or multiple mesh surfaces that are closely attached to each other, or metal honeycomb plate, or metal corrugated plate, or sponge metal plate, respectively.

[0023] Preferably, the fluid channel is located in the front-to-back horizontal direction, and the first discharge electrode, the second discharge electrode, and the blocking medium are arranged in the left-to-right vertical direction.

[0024] Preferably, a flow equalization plate is provided in front of the first discharge electrode, the surface of the flow equalization plate is located in the cross-sectional direction of the fluid channel, the alternating voltage between the first discharge electrode and the second discharge electrode is 6000V-60000V, and the thickness of the first discharge electrode and the second discharge electrode is 5mm-35mm respectively.

[0025] Preferably, the flow equalization plate has flow equalization holes with a diameter of 10mm-25mm evenly distributed on its surface, and the flow equalization plate is made of stainless steel or color steel plate.

[0026] Preferably, the fluid channel is located in the front-to-back horizontal direction, and a spray pipe is provided above the first discharge electrode, the second discharge electrode and the blocking medium. The spray pipe is provided with multiple nozzles, which can spray water onto the first discharge electrode, the second discharge electrode and the blocking medium. A guide groove is provided below the first discharge electrode, the second discharge electrode and the blocking medium.

[0027] The radial flow dielectric barrier discharge device of this invention can generate low-temperature plasma at room temperature through high-frequency high-voltage power supply discharge. When a sufficiently high AC voltage is applied between the two electrodes, the first discharge electrode and the second discharge electrode will break down, generating a discharge. Dielectric barrier discharge can be used to remove recalcitrant substances from waste gas. Because the barrier medium is a fluid-permeable plate, and the plate surface of the barrier medium is arranged along the direction that can block the fluid channel, the exhaust gas flows through the barrier medium along the discharge direction of the first discharge electrode and the second discharge electrode. Since the barrier medium of the present invention has a fluid-permeable structure, more fluid that needs to be treated can flow through the flue gas flow device. That is to say, for equipment of the same volume, the present invention has a higher fluid processing flow rate, lower resistance, and is more energy-efficient in operation. It also allows free electrons, ions, active groups and other particles in the plasma generated by the discharge to be mixed into the exhaust gas very uniformly. The fact that the exhaust gas flows through the barrier medium along the discharge direction of the first discharge electrode and the second discharge electrode also helps the medium barrier discharge device generate more plasma, making the present invention have a better treatment effect on the exhaust gas. At the same time, the airflow passing through the first discharge electrode and the second discharge electrode can also cool the first discharge electrode and the second discharge electrode well, preventing the temperature from rising to a higher level.

[0028] To address the issues of short catalyst activity time and narrow operating temperature window in existing SCR denitrification technologies, the present invention utilizes a flow-through dielectric barrier discharge device with a fluid-permeable plate-shaped barrier medium. The plate surface of the barrier medium is arranged along a direction that blocks the fluid flow channel, allowing the flue gas requiring denitrification to flow through the barrier medium along the discharge direction of the first and second discharge electrodes. Because the barrier medium of the present invention has a fluid-permeable structure, it allows more flue gas to be treated to flow through the device. In other words, for equipment of the same volume, the present invention provides a higher flue gas flow rate and lower air resistance. Smaller in size and more energy-efficient in operation, this device allows free electrons, ions, and active groups from the plasma generated by the discharge to be uniformly mixed into the flue gas requiring denitrification. The flue gas flows through the barrier medium along the discharge direction of the first and second discharge electrodes, which also helps the dielectric barrier discharge device generate more plasma. Because the radial flow dielectric barrier discharge device of this invention can generate more low-temperature plasma at room temperature through high-frequency, high-voltage power supply discharge, it promotes the conversion of nitrogen oxides in the flue gas into nitrogen and water by ammonia, thus improving the treatment effect on the flue gas requiring denitrification. Therefore, the radial flow dielectric barrier discharge device of this invention has the characteristics of large fluid processing capacity, good treatment effect, stable operation, long service life, and more efficient treatment of nitrogen oxides in flue gas, promoting the conversion of nitrogen oxides in the flue gas into nitrogen and water by ammonia.

[0029] Further details and features of the radial dielectric barrier discharge device of the present invention will become clear from the embodiments described in detail below in conjunction with the accompanying drawings. Attached Figure Description

[0030] Figure 1 This is a front cross-sectional view of the structural schematic diagram of the radial flow dielectric barrier discharge device of the present invention.

[0031] Figure 2 for Figure 1 Top view sectional view. Detailed Implementation

[0032] like Figure 1 and Figure 2 As shown, the radial flow dielectric barrier discharge device of the present invention includes a housing 1, a fluid channel 2 is provided inside the housing 1, a first discharge electrode 3 and a second discharge electrode 4 made of conductive material are provided inside the fluid channel 2, and a barrier medium 5 made of insulating material is provided between the first discharge electrode 3 and the second discharge electrode 4. The barrier medium 5 is a plate that is permeable to fluid, and the plate surface of the barrier medium 5 is arranged along the direction that can block the fluid channel 2.

[0033] Because the barrier medium 5 of the present invention has a fluid-permeable structure, it allows more fluid to be processed to flow through the flue gas flow device. In other words, for equipment of the same volume, the present invention has a higher fluid processing flow rate, lower resistance, and is more energy-efficient to operate. It also allows free electrons, ions, active groups and other particles in the plasma generated by the discharge to be mixed very evenly into the flue gas that needs to be denitrified.

[0034] As a further improvement of the present invention, the first discharge electrode 3 and / or the second discharge electrode 4 are plate-shaped with fluid permeable surfaces, and the surfaces of the first discharge electrode 3 and / or the second discharge electrode 4 are arranged along the direction that can block the fluid channel 2.

[0035] The first discharge electrode 3 and / or the second discharge electrode 4 are plate-shaped with fluid permeability. Because of the fluid permeability structure, more fluid to be treated can flow through the flue gas flow device. In other words, for equipment of the same volume, the present invention has a higher fluid processing flow rate, lower resistance, and is more energy-efficient to operate. It also allows free electrons, ions, active groups and other particles in the plasma generated by the discharge to be mixed very evenly into the flue gas that needs to be denitrified.

[0036] As a further improvement of the present invention, a third discharge electrode 7 made of conductive material is provided behind the second discharge electrode 4. The third discharge electrode 7 is plate-shaped with a surface permeable to fluid. The surface of the third discharge electrode 7 is arranged along the direction that can block the fluid channel 2. A second blocking medium 8 made of insulating material is provided between the second discharge electrode 4 and the third discharge electrode 7. The second blocking medium 8 is plate-shaped with a surface permeable to fluid. The surface of the second blocking medium 8 is arranged along the direction that can block the fluid channel 2.

[0037] The aforementioned second barrier medium 8 and third discharge electrode 7 are plate-shaped plates with fluid permeability. Because they are fluid-permeable structures, more fluid that needs to be treated can flow through the flue gas flow device. In other words, for equipment of the same volume, the present invention has a higher fluid processing flow rate, lower resistance, and is more energy-efficient in operation. It also allows free electrons, ions, active groups and other particles in the plasma generated by the discharge to be mixed very evenly into the flue gas that needs to be denitrified.

[0038] As a further improvement of the present invention, the above-mentioned blocking medium 5 and the second blocking medium 8 are microporous ceramics or organic porous foam materials that can filter fluids.

[0039] As a further improvement of the present invention, the first discharge electrode 3, the second discharge electrode 4 and the third discharge electrode 7 are respectively made of foam metal plate or multiple mesh surfaces closely attached to each other, or metal honeycomb plate or metal corrugated plate or sponge metal plate.

[0040] As a further improvement of the present invention, the fluid channel 2 is located in the front-to-back horizontal direction, and the first discharge electrode 3, the second discharge electrode 4 and the blocking medium 5 are arranged in the left-to-right vertical direction.

[0041] As a further improvement of the present invention, a flow equalization plate 6 is provided in front of the first discharge electrode 3, the plate surface of the flow equalization plate 6 is located in the cross-sectional direction of the fluid channel 2, the alternating voltage between the first discharge electrode 3 and the second discharge electrode 4 is 6000 volts to 60000 volts, and the thicknesses of the first discharge electrode 3 and the second discharge electrode 4 are 5 mm to 35 mm, respectively.

[0042] As a further improvement of the present invention, the flow equalization plate 6 is provided with flow equalization holes of 10mm-25mm in diameter on its surface, and the flow equalization plate 6 is made of stainless steel or color steel plate.

[0043] As a further improvement of the present invention, the fluid channel 2 is located in the front-to-back horizontal direction. A spray pipe 10 is provided above the first discharge electrode 3, the second discharge electrode 4 and the blocking medium 5. A plurality of nozzles 11 are provided on the spray pipe 10. The plurality of nozzles 11 can spray water onto the first discharge electrode 3, the second discharge electrode 4 and the blocking medium 5. A guide groove 12 is provided below the first discharge electrode 3, the second discharge electrode 4 and the blocking medium 5.

[0044] The spray pipe 10 is equipped with multiple nozzles 11 for cleaning the first discharge electrode 3, the second discharge electrode 4 and the blocking medium 5, while the guide channel 12 is used to guide the cleaned water to the outflow device.

[0045] The radial flow dielectric barrier discharge device of this invention can generate low-temperature plasma at room temperature through high-frequency, high-voltage power supply discharge. Specifically, it connects an alternating current (AC) to the first discharge electrode 3 and the second discharge electrode 4, both made of conductive material. The power supply frequency can range from 50Hz to 1MHz. When a sufficiently high AC voltage is applied between the two electrodes, the first discharge electrode 3 and the second discharge electrode 4 will break down, generating a discharge, i.e., dielectric barrier discharge. Dielectric barrier discharge can be used to remove recalcitrant substances from waste gas. Since the blocking medium 5 is a fluid-permeable plate, and the plate surface of the blocking medium 5 is arranged along the direction that can block the fluid channel 2, the exhaust gas flows through the blocking medium 5 along the discharge direction of the first discharge electrode 3 and the second discharge electrode 4. Because the blocking medium 5 of the present invention has a fluid-permeable structure, it can allow more fluid to be treated to flow through the flue gas flow device. That is to say, for equipment of the same volume, the present invention has a higher fluid processing flow rate, lower resistance, and is more energy-efficient in operation. It can also allow free electrons, ions, active groups and other particles in the plasma generated by the discharge to be mixed into the exhaust gas very evenly. The fact that the exhaust gas flows through the blocking medium 5 along the discharge direction of the first discharge electrode 3 and the second discharge electrode 4 also helps the medium blocking discharge device to generate more plasma, making the present invention have a better treatment effect on the exhaust gas. At the same time, the airflow passing through the first discharge electrode 3 and the second discharge electrode 4 can also cool the first discharge electrode 3 and the second discharge electrode 4 well, preventing the temperature from rising to a higher level.

[0046] Furthermore, the runoff dielectric barrier discharge device of the present invention can also be used as an ozone generator to produce ozone.

[0047] To address the issues of short catalyst activity time and narrow operating temperature window in existing SCR denitrification technologies, the present invention utilizes a radial-flow dielectric barrier discharge device. The barrier medium 5 of this invention is a fluid-permeable plate, with its surface arranged along the direction that blocks the fluid channel 2. This design allows the flue gas requiring denitrification to flow through the barrier medium 5 along the discharge direction of the first discharge electrode 3 and the second discharge electrode 4. This enables free electrons, ions, and active groups in the plasma generated by the discharge to be uniformly mixed into the flue gas requiring denitrification. Furthermore, the fact that the flue gas flows through the barrier medium 5 along the discharge direction of the first discharge electrode 3 and the second discharge electrode 4 helps the dielectric barrier discharge device generate more plasma. Since the radial-flow dielectric barrier discharge device of this invention can generate more low-temperature plasma at room temperature through high-frequency, high-voltage power discharge, it promotes the conversion of nitrogen oxides in the flue gas into nitrogen and water by ammonia, thus improving the treatment effect of the present invention on the flue gas requiring denitrification. Therefore, the runoff dielectric barrier discharge device of the present invention has the characteristics of large fluid processing capacity, good processing effect, stable working performance, long service life, and can more efficiently treat nitrogen oxides in flue gas, promoting ammonia to convert nitrogen oxides in flue gas into nitrogen and water.

Claims

1. A flow-type dielectric barrier discharge device, comprising a housing (1), a fluid channel (2) provided inside the housing (1), a first discharge electrode (3) and a second discharge electrode (4) made of conductive material provided inside the fluid channel (2), and a barrier medium (5) made of insulating material provided between the first discharge electrode (3) and the second discharge electrode (4), characterized in that... The blocking medium (5) is a plate that is permeable to fluid, and the plate surface of the blocking medium (5) is arranged along the direction that can block the fluid channel (2); The first discharge electrode (3) and the second discharge electrode (4) can be connected to AC power. When a sufficiently high AC voltage is applied between the two electrodes, the first discharge electrode (3) and the second discharge electrode (4) will be broken down and discharge will occur. The first discharge electrode (3) and the second discharge electrode (4) are plate-shaped plates with fluid permeable surfaces, and the surfaces of the first discharge electrode (3) and the second discharge electrode (4) are arranged along the direction that can block the fluid channel (2).

2. The radial flow dielectric barrier discharge device according to claim 1, characterized in that... A third discharge electrode (7) made of conductive material is provided behind the second discharge electrode (4). The third discharge electrode (7) is a plate with a surface that allows fluid to pass through. The surface of the third discharge electrode (7) is arranged along the direction that can block the fluid channel (2). A second blocking medium (8) made of insulating material is provided between the second discharge electrode (4) and the third discharge electrode (7). The second blocking medium (8) is a plate with a surface that allows fluid to pass through. The surface of the second blocking medium (8) is arranged along the direction that can block the fluid channel (2).

3. The radial flow dielectric barrier discharge device according to claim 2, characterized in that... The blocking medium (5) and the second blocking medium (8) are microporous ceramics or organic porous foam materials that can filter fluids.

4. The radial flow dielectric barrier discharge device according to claim 3, characterized in that... The first discharge electrode (3), the second discharge electrode (4) and the third discharge electrode (7) are respectively made of foam metal plate or multiple mesh surfaces closely attached to each other, metal honeycomb plate or metal corrugated plate or sponge metal plate.

5. The radial flow dielectric barrier discharge device according to any one of claims 1 to 4, characterized in that... The fluid channel (2) is located in the front-to-back horizontal direction, and the first discharge electrode (3), the second discharge electrode (4) and the blocking medium (5) are arranged in the left-to-right vertical direction.

6. The radial flow dielectric barrier discharge device according to claim 5, characterized in that... A flow equalization plate (6) is provided in front of the first discharge electrode (3). The plate surface of the flow equalization plate (6) is located in the cross-sectional direction of the fluid channel (2). The alternating voltage between the first discharge electrode (3) and the second discharge electrode (4) is 6000 volts to 60000 volts. The thicknesses of the first discharge electrode (3) and the second discharge electrode (4) are 5 mm to 35 mm, respectively.

7. The radial flow dielectric barrier discharge device according to claim 6, characterized in that... The flow equalization plate (6) has flow equalization holes with a diameter of 10mm-25mm evenly distributed on its surface. The flow equalization plate (6) is made of stainless steel or color steel plate.

8. The radial flow dielectric barrier discharge device according to claim 7, characterized in that... A spray pipe (10) is provided above the first discharge electrode (3), the second discharge electrode (4) and the barrier medium (5). The spray pipe (10) is provided with multiple nozzles (11). The multiple nozzles (11) can spray water onto the first discharge electrode (3), the second discharge electrode (4) and the barrier medium (5). A guide groove (12) is provided below the first discharge electrode (3), the second discharge electrode (4) and the barrier medium (5).

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