JP4200750B2 - Exhaust purification device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention can collect particulate matter mainly containing carbon (hereinafter referred to as PM) contained in exhaust gas such as a diesel engine in the entire operation region, and collects and oxidizes the collected PM even at a low temperature. The present invention relates to an exhaust purification device capable of recovering.
[0002]
[Prior art]
Conventionally, exhaust gas from a diesel engine contains PM composed of carbon, SOF (Soluble Organic Fraction), a polymer organic compound, sulfuric acid mist, and the like, and suppression of this PM emission has been strengthened from the viewpoint of environmental improvement.
[0003]
Conventionally, a charge-type diesel particulate filter device combining a charging device and a filter has been proposed in order to suppress PM emission (Japanese Patent Laid-Open No. 2001-41024). In addition, a diesel particulate filter system that uses a conductive diesel particulate filter and charges and collects between the conductive filters has been proposed (Japanese Patent Laid-Open No. 2001-20721).
[0004]
[Problems to be solved by the invention]
That is, since the former charge type diesel particulate filter device uses an electric heater for regeneration of the collection unit, it is necessary to heat the entire collection unit in addition to the PM to be burned, which requires a great deal of energy. . For this reason, the former charge-type diesel particulate filter device has a problem that the fuel consumption loss is large and which should be solved practically.
[0005]
In the latter diesel particulate filter system, the regeneration of the collection unit is controlled on the basis of the exhaust temperature rise by the internal combustion engine. For this reason, the latter diesel particulate filter system needs to heat the whole collection part, requires a lot of energy, and has the problem which should be solved practically.
[0006]
In any of these conventional techniques, since no catalyst is supported on the collection part, PM combustion at a low temperature cannot be realized, and a large amount of energy is required from this viewpoint. Even when these conventional technologies carry a Pt-based oxidation catalyst, PM will not burn unless it is at a high temperature of 500 ° C. or higher.
[0007]
Further, as an oxidation catalyst, O ⁻ which is an active oxygen species. Ion radical and / or O ^- ₂ ion radicals has been proposed 12CaO · _7Al 2 _{O 3} compound (JP 2002-3218). However, there is no disclosure of an application to an exhaust gas purification device, and no disclosure suggesting this. That is, the disclosure of the contact state between the PM and the catalyst component, the oxidation combustion of the PM, the purification method by the combustion promotion effect, etc. is not recognized.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-41024 [0003]
[0009]
[Patent Document 2]
Japanese Patent Laid-Open No. 2001-20721 [0003]
[0010]
[Patent Document 3]
JP-A-2002-3218 [0007]
[0011]
The present invention has been devised to solve the above problems. That is, the object of the present invention is to collect particulate matter mainly composed of carbon (hereinafter referred to as PM) contained in exhaust gas such as a diesel engine in the entire operation region, and to collect PM even at a low temperature. It is an object of the present invention to provide an exhaust purification device capable of efficiently and accurately recovering a collection device by oxidizing and burning the gas.
[0012]
[Means for Solving the Problems]
An exhaust emission control device as claimed in claim 1, connected to a charging means for charging the particulate matter contained in exhaust gas, a collecting device for collecting particulate matter which is charged by the charging means, the high voltage generator And a combustion device for burning particulate matter collected by the collection device by applying a high voltage to the electrode, and the active oxygen is included in the electrode of the combustion device. wherein the ion radical and / or ^{_O -2} 12CaO · _7Al 2 ^O ₃ compound to produce an ionic radical and / or Ce oxide to produce atomic oxygen or CeO containing oxide is supported ^- O is species And
[0015]
[Operation and effect of the invention]
The exhaust emission control device of the present invention having the above-described configuration can collect particulate matter mainly containing carbon (hereinafter referred to as PM) contained in exhaust gas in the entire operation region, and collect the collected PM even at a low temperature. The effect | action and effect which can oxidatively burn and recover a collection apparatus efficiently and precisely are demonstrated.
[0016]
[Action: Reason for effect]
Specifically, the charging device applies a high voltage to the exhaust gas of the internal combustion engine to charge PM in the exhaust gas. The charged PM can be electrostatically collected by applying a high voltage in the collection device. In order to burn the collected PM by the combustion device, the PM can be oxidized by utilizing the heat of discharge by applying a high voltage. For the oxidation catalyst of the combustion device, O ⁻ which is an active oxygen species By supporting a substance capable of generating ion radicals and / or O ⁻ ₂ ion radicals and / or atomic oxygen, O ⁻ It can be improved ₂ ion radical and / or oxidation performance at contact with atomic oxygen to generate PM ^- ion radical and / or O.
[0017]
O is a reactive oxygen species ^- Ion radical and / or _{^{O - 2 12CaO · 7Al 2 O}} 3 compound capable of generating an ion radical can not allowed to rise to oxidation of the PM when not heated to above 600 ° C. alone. However, by composing a PM combustion device that combines a device that applies a high voltage to the 12CaO.7Al ₂ O ₃ compound, PM combustion can be realized efficiently and reliably from a low temperature. This is because the heat generated by the discharge due to the high voltage warms the 12CaO · 7Al ₂ O ₃ compound to 600 ° C. or higher, and the O ⁻ This is because it is possible to accurately promote an oxidation reaction with PM that is generated and collected in a large amount of ion radicals and / or O ⁻ ₂ ion radicals.
[0018]
In addition, Ce oxide or Ce-containing oxide capable of generating atomic oxygen, which is an active oxygen species, alone cannot cause PM oxidation unless it is heated to 300 ° C. or higher. As with the 7Al ₂ O ₃ compound, PM combustion can be reliably and efficiently realized from a low temperature by configuring the PM combustion device in combination with a device that applies a high voltage.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIGS. 1 to 4, the exhaust purification apparatus according to the embodiment of the present invention is such that the charging device 3 of the electrostatic collector 2 provided in the exhaust pipe 1 of the diesel engine conducts to the high voltage generator 4. Good connection. The charging electrode 5 of the charging device 3 is composed of a rod-shaped conductor, and a plurality of protrusions 6 are provided on the downstream side at predetermined intervals. Both ends of the charging electrode 5 are fixed to the electrostatic collector 2 by insulators 7 so that the axial direction is orthogonal to the flow of exhaust gas. The charging electrode 5 is connected to the negative electrode side of the DC power supply device of the high voltage generator 4. Since the charging electrode 5 is connected by the insulator 7, the charging electrode 5 is configured to be insulated from the case of the electrostatic collector 2. Then, the charging electrode 5 generates corona discharge through the protrusion 6 to charge the PM.
[0020]
On the downstream side of the charging device 3, a collecting device 8 that collects charged PM is installed. The collection device 8 is composed of a ceramic foam 9, and a combustion electrode 10 is inserted in the center. The electrode 10 is connected to either the positive or negative electrode side of the DC power supply device of the high voltage generator 11, and is configured to be able to apply a high voltage during combustion. The ceramic foam 9 of the collecting device 8 has O ⁻ Ion radical and / or _{^{O - 2 12CaO · 7Al 2 O}} 3 compound is an ionic radical and / or atomic oxygen many reactive oxygen species generated is carried.
[0021]
As shown in FIG. 2, the exhaust emission control device of the embodiment of the present invention having the above configuration is charged by the charging device 3 when PM discharged from the diesel engine is introduced into the electrostatic collection device 2. The charged PM is collected by the collecting device 8 by electrostatic force. During normal operation, this charging and collection occur continuously, and PM in the exhaust is removed. When a certain amount of PM is collected, the PM is forcibly burned.
[0022]
That is, in the combustion of PM, a high voltage is applied to the combustion electrode 10 and the PM is burned by discharge. At temperatures above the ignition point of PM, PM spontaneously burns. Further, if the substance generating active oxygen species supported on the ceramic foam 9 is active at a temperature below the ignition point of PM, O ⁻ released from the substance is used. Ion radical and / or O ^- by ₂ ion radicals and / or atomic oxygen, PM is burned. In the exhaust emission control device according to the embodiment of the present invention, PM can be burned by applying a high voltage even in a temperature range where the temperature is further lowered and the activity of the compound is lost.
[0023]
In this combustion mechanism, as shown in FIG. 3, when a high voltage is applied, a discharge occurs in the compound and heat is generated. This heat can raise the compound to the active temperature. For this reason, O ⁻ _Can be ₂ to encourage the generation of ion radical and / or atomic oxygen to promote combustion ^- ion radical and / or O. In addition, oxygen molecules in the atmosphere can be ionized and radicalized by discharge to promote combustion with PM. Thus, in the exhaust emission control device of the embodiment of the present invention, PM contained in exhaust gas can be collected in the entire operation region, and PM collected from high temperature to low temperature can be burned efficiently and accurately. The effect | action and effect which can recover | recover the collection apparatus 8 rapidly are demonstrated.
[0024]
That is, the exhaust gas purification apparatus according to the embodiment of the present invention performed an exhaust gas purification experiment at a temperature of 200 ° C. together with each comparison object as shown in FIG. 4, and as a result, excellent PM combustion performance was obtained. In the figure, (1) is an embodiment of the present invention, (2) is not discharged to 12CaO.7Al ₂ O ₃ compound, (3) is discharged with Al ₂ O ₃ , (4) is Pt-based It is a catalyst.
[0025]
[Other embodiments]
In the exhaust purification apparatus of the present invention, the O ⁻ as in the above embodiment. Ion radical and / or O ^- ₂ ion radicals and / or 12CaO · _7Al 2 _{O 3} compound frequently occurs atomic oxygen is not limited to Ce oxide or Ce-containing oxide, O ^- ion radical and / or O ^- ₂ A catalyst having a function of releasing other oxygen active species that generates ion radicals and / or atomic oxygen can be used.
[0026]
The exhaust emission control device of the present invention is not limited to the diesel engine in the above-described embodiment, but may be a gasoline engine that realizes lean combustion. Also, exhaust gas from a gas turbine and a boiler for heating is used for PM and NOx. The present invention can be applied to various devices such as a purifying device.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an exhaust emission control device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a state where PM charged and charged in the charging device according to the embodiment of the present invention is collected.
FIG. 3 is a diagram showing a combustion mechanism of PM collected by the collection device according to the embodiment of the present invention.
FIG. 4 is a diagram showing the combustion effect of PM in the exhaust emission control device according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Exhaust pipe 2 ... Electrostatic collection device 3 ... Charging device 4 ... High voltage generator 5 ... Charging electrode 6 ... Projection part 8 ... Collection device 9 ... Ceramic foam

Claims (1)

Charging means for charging particulate matter contained in the exhaust gas;
A collection device for collecting particulate matter charged by the charging means ;
A combustion apparatus that has an electrode connected to a high voltage generator and burns particulate matter collected by the collector by applying a high voltage to the electrode ;
Wherein the said electrodes of the combustion apparatus, O is a reactive oxygen species ^- Ce oxide or CeO generating a 12CaO · _7Al 2 _{O 3} compound to produce an ionic radical and / or ^{O -2} ions radical and / or atomic oxygen An exhaust emission control device, wherein a contained oxide is supported .

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