JP2003038933A - Discharge plasma generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge plasma generating apparatus for purifying a waste gas, in which stable discharge field is formed, by forming an oil film of engine oil, silicone oil or the like on the surface of one or both of a high voltage electrode and a ground electrode to function as an insulating film. SOLUTION: This discharge plasma reaction apparatus is composed of the high voltage electrode 11, the ground electrode 12, a filter 13, an electrode supporting part 14 and insulating oil 15. The high voltage electrode is a metal- made brush, the ground electrode is a metal-made pipe, the filter is an incombustible filter and the insulating oil is circulated in the discharge plasma generating apparatus with a pump 16. Sparking voltage between the electrodes is increased by forming the oil film on the inside surface of the ground electrode and the surface of the high voltage electrode. Further, the electrode supporting part is cleaned with the oil to suppress the lowering of the insulation due to the sticking of soot, or the like, and as a result, the discharge plasma is stabilized, NO or a volatile organic compound in the gas is cleaned and the collection efficiency of the soot is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge plasma generator used for treating harmful gases such as soot and volatile organic compounds generated in a combustion engine or a combustion device.

[0002]

2. Description of the Related Art Conventionally, by sandwiching an insulator such as ceramics or glass between a high voltage electrode and a ground electrode of a discharge plasma generator, spark destruction is suppressed and stable discharge plasma is formed.

The discharge plasma is effective for the oxidation of NO in combustion exhaust gas, and lower hydrocarbons such as ethylene are used as an additive to accelerate the oxidation.

In the electrostatic precipitator, suspended particulate matter (hereinafter referred to as SPM) is charged by corona discharge plasma and separated from gas with high efficiency by electric force.

[0005]

However, the insulator used for generating stable discharge plasma is expensive, and there is a problem in durability such as mechanical strength for long-term use.

Further, in purifying exhaust gas having a large amount of soot and moisture, these adhere to the high voltage introducing portion for plasma generation, causing dielectric breakdown and making it impossible to stably apply voltage. Further, in order to use a lower hydrocarbon such as ethylene for NO oxidation, an auxiliary facility for storing it in a container is required.

Since soot has a low electrical resistivity, abnormal re-scattering occurs in the electrostatic precipitator. This is a phenomenon in which particles once trapped in the ground electrode jump out again, which makes it difficult to collect soot particles.

[0008]

SUMMARY OF THE INVENTION The present invention is to solve the above problems, and in an electric discharge plasma generator, an oil film such as engine oil or silicone oil is formed on the surface of one or both of the high voltage electrode and the ground electrode. Is formed, and a stable discharge field is formed by using this as an insulating film.

Further, the high voltage introducing portion is washed with oil to maintain dielectric strength.

It is characterized by forming an oil film on the surface of the ground electrode to suppress abnormal re-scattering.

Further, as an additive for accelerating NO oxidation, light oil or gasoline having a high vapor pressure is mixed with the engine oil or silicone oil for use.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a discharge plasma generator according to the present invention. The discharge plasma generator includes a high voltage electrode 11, a ground electrode 12, a filter 13, and an electrode supporting portion 1.
4 and insulating oil 15.

The high voltage electrode 11 is, for example, a metal brush. The ground electrode 12 is, for example, a metal pipe. The filter is a nonflammable filter. Besides this,
As the high voltage electrode, a wire, a square wire, a blade shape, or the like having a shape capable of forming an uneven electric field can be used. The ground electrode may have a flat shape such as a flat plate as well as a cylindrical shape.

The inner surface of the ground electrode 12 may be smooth,
In order to form the oil film more uniformly, a layer that absorbs oil such as glass cloth may be provided.

The insulating oil 15 is circulated to the discharge plasma generator by the pump 16.

The high-voltage pulse power supply 17 includes the high-voltage electrode 11
By applying a pulse voltage between the ground electrode 12 and the ground electrode 12, a pulse streamer discharge is generated and a discharge plasma field 18 is created. Alternatively, an alternating voltage or a DC voltage may be used.

The gas containing NOx, SPM, etc. is introduced into the discharge plasma generator.

The SPM in the discharge plasma field 18 is collected on the inner wall of the ground electrode 12 due to the electric dust collection effect. FIG. 2 shows the dust collection effect when diesel exhaust gas is treated by this discharge plasma generator. It is the comparison which processed gas was filtered with the filter.

Further, FIG. 3 shows the measurement results of fine particles contained when the room air was treated by this discharge plasma apparatus. Good SPM removal is possible by applying a high voltage.

The NO-containing air in the discharge field 18 is oxidized by discharge plasma.

Further, by using light oil as an additive,
The NO oxidation reaction can be promoted. The result is shown in FIG.

[0023]

According to the first aspect of the present invention, stable discharge plasma can be obtained without sandwiching an expensive insulator having a problem with durability between electrodes. In addition, it is possible to suppress abnormal re-scattering of particles such as soot having a low electric resistivity and to collect dust with high efficiency.

Further, NO can be oxidized by the discharge plasma, and NO and SPM can be removed simultaneously.

According to the second aspect of the present invention, it is possible to prevent the dielectric breakdown due to the SPM attached to the electrode supporting portion, and it is possible to perform a stable exhaust gas treatment for a long time.

According to the third aspect of the invention, it is said that by lightening light oil or the like to lower hydrocarbons in the discharge field, it is an additive effective for promoting the NO oxidation reaction and reducing power consumption. Lower hydrocarbons can be supplied, and the cost of additives can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a plasma generator according to the present invention.

FIG. 2 is a diagram showing SPM removal in diesel exhaust gas.

FIG. 3 is a graph showing removal of fine particles from indoor air.

FIG. 4 is a graph showing NO removal in diesel exhaust gas.

[Explanation of symbols]

11 High voltage electrode 12 Ground electrode 13 filters 14 Electrode support 15 insulating oil 16 pumps 17 High voltage pulse power supply 18 discharge plasma field

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/02 301 H05H 1/24 3/08 B01D 53/34 129C H05H 1/24 (72) Inventor Matsui Yoshihiko 44-1 Ashihara, Ashihara-cho, Toyohashi-shi, Aichi (72) Inventor Masayuki Hashimoto 11-1 Miyoshi, Tenhaku-cho, Toyohashi-shi, Aichi F-term (reference) 3G090 AA06 BA08 3G091 AA18 AB14 BA07 BA15 CA15 FB10 4D002 AA12 AA40 AC10 BA05 BA07 BA14 CA20 HA02 4D054 AA02 AA03 BA01 BB10 BC24 4G075 AA03 AA37 BA01 BA06 BD12 CA15 CA57 DA02 EA01 EB01 EB41 EC06 EC13 EC21 EE07 EE12 FC02 FC15

Claims (3)

[Claims] 1. A dielectric breakdown between electrodes is prevented by forming an insulating oil film on the surfaces of the electrodes facing each other.
Discharge plasma generator. 2. The discharge plasma according to claim 1, wherein the insulating oil is used to clean the surface of the electrode supporting portion that comes into contact with the gas to prevent dielectric breakdown of the electrode supporting portion. Generator. 3. By mixing light oil or the like into the insulating oil,
The discharge plasma generator according to claim 1 or 2, which promotes treatment of polluted gas.