JP2005288239A - Discharge type gas purification apparatus and gas purification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge type gas purification apparatus and a purification method for removing fine solid or liquid particles contained in gas as impurities from gas for purifying. <P>SOLUTION: This discharge type gas purification apparatus comprises in a facing state arranged electrodes 2a, 2b with different effective areas, a high frequency power source 1 generating high frequency discharge between the electrodes by applying voltage to the electrodes, and a gas circulating means for circulating gas containing fine particles between the electrodes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discharge-type gas purification device and a gas purification method for purifying a gas containing harmful substances and the like by discharge.

  Removal of odors and harmful substances discharged from water treatment facilities, livestock breeding facilities, factories, etc. is an important modern technological development issue. Various methods have been developed for this exhaust gas treatment method, such as a method using an adsorbent or a catalyst, a method of dissolving and absorbing in an aqueous solution of a drug, and a method using discharge plasma (Patent Document 1). Among these, the method using the discharge plasma has a feature that the amount of the waste material containing the material to be treated can be reduced.

  As an example of a conventional exhaust gas purifying apparatus to which discharge plasma is applied, a plasma deodorizing apparatus will be described with reference to the drawings. FIG. 10 is a schematic block diagram of the plasma deodorization apparatus, in which 21 is a discharge processing unit, 22 is an adsorption decomposition processing unit, 23 is an exhaust fan, and 24 is an exhaust duct. Air containing a large amount of odor components sucked into the exhaust duct 24 by the exhaust fan 23 is first decomposed by the discharge plasma in the discharge processing section 22. Components that are not treated by the discharge plasma are adsorbed by activated carbon provided in the adsorption / decomposition processing unit 22 or decomposed by a catalyst. Further, since ozone generated in the discharge processing unit 21 has a long life, it stays in the adsorption decomposition processing unit 22 for a long time, for example, and contributes to decomposition of odor components.

By the way, the impurities that the conventional discharge gas purification devices have dealt with are gaseous substances, but the exhaust gas treatment contains fine particles such as combustion smoke from factories and soot discharged from ships, automobile diesel engines and gasoline engines. The expectation of application to is also great.
However, the conventional discharge gas purification apparatus does not consider the treatment of fine particles even when the exhaust gas contains fine particles.

  Therefore, the present invention provides a discharge gas purification device and a gas purification method capable of removing and purifying fine particles from a gas containing solid or liquid minute objects (hereinafter referred to as fine particles) as impurities. Objective.

According to the first aspect of the present invention, there are provided electrodes having different effective areas disposed opposite to each other, a high-frequency power source for applying a voltage to the electrodes to generate a high-frequency discharge between the electrodes, and a gas flow containing fine particles between the electrodes. And a gas flow means.
According to a second aspect of the present invention, at least one opposing surface of the electrode is covered with a dielectric.

According to a third aspect of the present invention, the electrode having a smaller effective area is composed of a plurality of electrically connected strip-shaped metal plates, and the other is composed of a single flat plate.
According to a fourth aspect of the present invention, the plurality of strip-shaped metal plates are combined in a lattice shape.

According to a fifth aspect of the present invention, the electrode having a smaller effective area is composed of a metal flat plate having a plurality of holes, and the other is composed of a single flat plate.
The invention of claim 6 comprises electrodes arranged opposite to each other, a high frequency power source for applying a voltage to the electrodes to generate a high frequency discharge between the electrodes, a direct current power source connected in series to the high frequency power source, and the electrodes A gas flow means for allowing a gas containing fine particles to flow there between is provided.

According to a seventh aspect of the present invention, a capacitor is connected in parallel with the DC power supply.
According to an eighth aspect of the present invention, a plurality of sets of electrodes are provided in a stacked manner.
According to a ninth aspect of the present invention, an ionization device for charging fine particles in the gas is provided in a stage preceding the discharge processing unit including the electrode.

  According to a tenth aspect of the present invention, there is provided a method in which a high frequency discharge is generated between electrodes arranged opposite to each other and having a potential bias, a gas containing fine particles is passed between the electrodes, and the fine particles are captured and decomposed by the electrodes.

  INDUSTRIAL APPLICABILITY The present invention can provide a discharge-type gas purification device and a gas purification method that can remove and purify fine particles from a gas that contains solid or liquid minute objects (hereinafter referred to as fine particles) as impurities. .

Hereinafter, first to ninth embodiments of the present invention will be described with reference to the drawings.
First, a first embodiment will be described with reference to FIG. FIG. 1A is a diagram illustrating a configuration of a discharge processing unit of the discharge gas purification apparatus according to the present embodiment, and FIG. 1B is a diagram illustrating a voltage waveform between electrodes.

  In FIG. 1A, 1 is a high-frequency power source, and 2a and 2b are electrodes arranged in parallel. 3 is discharge plasma generated between the electrodes 2a and 2b, and 4 is a capacitor. The gas containing fine particles flows in the direction of the arrow in the figure and is oxidatively decomposed in the discharge space.

  In the discharge type gas purification apparatus of the present embodiment, the parallel electrodes 2 a and 2 b facing each other are different in size, and the electrode 2 a is connected to the ground point 5 through the capacitor 4. By doing so, as shown in FIG. 1B, the voltage between the electrodes becomes asymmetric with respect to the 0V line, and the average potential of the electrode 2b becomes positive. This is called self-bias. As a result, the fine particles charged in the discharge plasma 3 are attracted to one electrode by the electric field and collected on the electrode surface. The time constant of reaction of fine particles is longer than that of gas. Therefore, by attaching to the electrode in this way, the time of exposure to plasma can be lengthened and the amount of processing can be increased.

  The discharge type gas purification apparatus according to the present embodiment reduces the area of one of the discharge electrodes 2a and 2b with the parallel plates facing each other smaller than the other, and generates a steady potential difference between the electrodes 2a and 2b when generating a high frequency discharge. It is generated. In this discharge-type gas purification apparatus, the fine particles in the gas are charged between the electrodes, and at the same time, attracted to one of the electrodes by the action of the electrostatic field generated between the electrodes and attached thereto. By treating this with the action of discharge plasma, fine particles contained in the gas can be removed simultaneously with the gaseous impurities.

  FIG. 2 is a diagram illustrating a configuration of a main part of a discharge processing unit of the discharge gas purification apparatus according to the second embodiment of the present invention. That is, the surface of one electrode 2a is covered with the insulating material 6. By doing so, the arc discharge between the electrodes 2a and 2b is suppressed by the insulating material 6, and high energy can be input stably to the discharge plasma, and the gas purification treatment capacity is improved.

  FIG. 3 is a schematic diagram for explaining a third embodiment of the present invention. In this embodiment, as shown in FIG. 3A, the outer shapes and dimensions of the electrodes 2a and 2c constituting the discharge processing section are substantially the same. The electrode 2c is composed of a plurality of strip-like metal plates 2c1 and 2c2 that are electrically connected to one electrode 2a made of a metal flat plate as shown in FIG. 3B. The effective area of the electrode 2c is smaller than that of the electrode 2a. As a result, like the electrodes 2a and 2b shown in FIG. 1A, a self-bias is generated, and a steady electric field is generated between the electrodes 2a and 2c.

  FIG. 4 is a schematic diagram for explaining a fourth embodiment of the present invention. In this embodiment, one electrode 2c in the electrode configuration shown in FIG. 3 (a) is configured by combining strip-shaped metal plates 2c1 and 2c3 in a lattice pattern. Also in this embodiment, as in FIG. 3B, the effective area of the electrode 2c is smaller than that of the opposing electrode 2a. As a result, like the electrodes 2a and 2b shown in FIG. 1A, a self-bias is generated, and a steady electric field is generated between the electrodes 2a and 2c.

  FIG. 5 is a schematic diagram for explaining a fifth embodiment of the present invention. In this embodiment, as shown in FIG. 3A, the electrode 2c facing the flat plate electrode 2a is constituted by a metal flat plate having a large number of holes, and the effective area is made smaller than that of the electrode 2a. As a result, like the electrodes 2a and 2b shown in FIG. 1A, a self-bias is generated, and a steady electric field is generated between the electrodes 2a and 2c.

  FIG. 6 is a schematic diagram for explaining a sixth embodiment of the present invention. In this embodiment, a DC power supply 7 is connected in series with the discharge electrode portion 2. The direct-current power source 7 further increases the self-bias potential shown in FIG. 1B, thereby improving the particulate collection efficiency. Note that the polarity of the connection of the DC power supply 7 may be opposite to that shown in the figure. Further, since the potential bias is applied by the DC power source 7, the areas of the opposing electrodes may be the same.

  FIG. 7 is a schematic diagram for explaining a seventh embodiment of the present invention. In this embodiment, a capacitor 4 is connected in parallel to a DC power source 7 connected in series with the discharge electrode portion 2. The DC power source 7 must have a sufficiently low impedance with respect to a high frequency, but when this is not sufficient, the high frequency impedance can be kept low by the capacitor 4. Note that the polarity of the connection of the DC power supply 7 may be opposite to that shown in the figure. Further, the areas of the opposing electrodes may be the same.

  FIG. 8 is a schematic view of a discharge processing unit for explaining an eighth embodiment of the present invention. In this embodiment, a pair of electrodes 2a1, 2a2, 2a3 having the same potential and another pair of electrodes 2b1, 2b2 having the same potential are alternately arranged, and a discharge plasma 3 is formed between the electrodes. It was made to do. According to this embodiment, the processing cross-sectional area increases with respect to the gas flow from the direction indicated by the arrow, and sufficient processing capacity can be obtained even for a large flow rate of gas. The electrodes 2a2, 2b1, and 2b2 may have a floating potential between the potential of the electrode 2a1 and the potential of the electrode 2a3.

  FIG. 9 is an overall schematic view of a discharge gas purification apparatus according to the ninth embodiment of the present invention. In this embodiment, an ionization device 9 for charging fine particles in the exhaust gas is installed in the preceding stage of the discharge processing unit 21. According to this embodiment, not only the action of the discharge processing unit 21 but also the ionization device 9 further increases the charge amount of the fine particles in the gas and improves the collection efficiency of the fine particles in the discharge space.

The discharge type gas purification apparatus of the 1st Embodiment of this invention is shown, (a) is a figure which shows the structure of a discharge process part, (b) is a figure which shows the voltage waveform between electrodes. The figure which shows the structure of the principal part of the discharge processing part with which the discharge type gas purification apparatus of the 2nd Embodiment of this invention is equipped. The discharge type gas purification apparatus of the 3rd Embodiment of this invention is shown, (a) is a figure which shows the principal part structure of a discharge process part, (b) is a figure which shows the structure of one electrode. The figure which shows the structure of one electrode with which the discharge process part in the discharge type gas purification apparatus of the 4th Embodiment of this invention is equipped. The figure which shows the structure of one electrode with which the discharge process part in the discharge type gas purification apparatus of the 5th Embodiment of this invention is equipped. The figure which shows the structure of the discharge process part with which the discharge type gas purification apparatus of the 6th Embodiment of this invention is equipped. The figure which shows the structure of the discharge process part with which the discharge type gas purification apparatus of the 7th Embodiment of this invention is equipped. The figure which shows the structure of the electrode of the discharge process part with which the discharge type gas purification apparatus of the 8th Embodiment of this invention is equipped. The figure which shows the structure of the discharge type gas purification apparatus of the 9th Embodiment of this invention. The figure which shows the conventional discharge-type gas purification apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... High frequency power supply, 2 ... Discharge electrode part, 2a, 2a1, 2a2, 2a3, 2b, 2b1, 2b2, 2c ... Electrode, 2c1, 2c2, 2c3 ... Strip-shaped metal plate, 3 ... Discharge plasma, 4 ... Capacitor, DESCRIPTION OF SYMBOLS 5 ... Grounding, 6 ... Insulating material, 7 ... DC power supply, 9 ... Ionizer, 21 ... Discharge process part, 22 ... Adsorption decomposition process part, 23 ... Exhaust fan, 24 ... Exhaust duct.

Claims (10)

  Electrodes with different effective areas arranged opposite to each other, a high-frequency power source for applying a voltage to the electrodes to generate a high-frequency discharge between the electrodes, and a gas flow means for flowing a gas containing fine particles between the electrodes A discharge-type gas purification apparatus comprising:   The discharge-type gas purification apparatus according to claim 1, wherein at least one facing surface of the electrode is covered with a dielectric.   2. The discharge type gas purification apparatus according to claim 1, wherein the smaller effective area of the electrode is composed of a plurality of electrically connected strip-shaped metal plates, and the other is composed of one flat plate.   4. The discharge type gas purification apparatus according to claim 3, wherein the plurality of strip-shaped metal plates are coupled in a lattice shape.   2. The discharge type gas purification apparatus according to claim 1, wherein the electrode having a smaller effective area is made of a metal flat plate having a plurality of holes, and the other is made of a single flat plate.   An electrode disposed oppositely, a high-frequency power source that applies a voltage to the electrode to generate a high-frequency discharge between the electrodes, a DC power source connected in series to the high-frequency power source, and a gas containing fine particles between the electrodes Discharge-type gas purification apparatus comprising gas flow means for allowing flow.   The discharge type gas purification apparatus according to claim 6, wherein a capacitor is connected in parallel with the DC power source.   The discharge type gas purification apparatus according to claim 1 or 6, wherein a plurality of sets of the electrodes are provided in a stacked manner.   The discharge type gas purification apparatus according to claim 1 or 6, further comprising an ionization device that charges fine particles in the gas before the discharge processing unit including the electrode. A gas purification method comprising: generating a high-frequency discharge between electrodes arranged opposite to each other and having a potential bias; causing a gas containing fine particles to flow between the electrodes; and capturing and decomposing the fine particles on the electrodes.

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