KR20000006954U - Hazardous Exhaust Gas Exhaust System - Google Patents

Abstract

The present invention relates to an exhaust system of an automobile, and efficiently removes nitrogen oxide components that are difficult to purify from an oxidizing atmosphere by using a photocatalyst, and stores a noble metal or nitrogen oxide adsorber, which is a three-way catalyst material, in a photocatalyst and contains unburned hydrocarbon components. It is an object of the present invention to provide an exhaust system of a vehicle for reducing harmful emissions, which can significantly reduce equipment costs for air pollution prevention as well as preventing air pollution. The present invention to achieve the above object is a plasma reactor installed in the middle of the exhaust pipe; A power supply for supplying power to the plasma reactor; An engine control unit controlling a power supply of the power supply; Located in the front of the plasma reactor, the photocatalyst reactor for purifying the nitrogen oxide component discharged with a large amount of oxygen in the exhaust gas in the oxidizing atmosphere and the unburned hydrocarbons, carbon monoxide in the exhaust gas located inside the plasma reactor And a three-way catalytic reactor to purify the components.

Description

Hazardous Exhaust Gas Exhaust System

The present invention relates to an exhaust system of a vehicle. More specifically, a photocatalyst is used to efficiently remove nitrogen oxide components that are difficult to purify from the oxidizing atmosphere, and the photocatalyst can be efficiently purified to remove unburned hydrocarbon components. The present invention relates to an exhaust system for a harmful exhaust gas-reducing type vehicle containing a noble metal or nitrogen oxide adsorber, which is a three-way catalyst material.

In general, in order to operate an engine of a vehicle, a mixer is sucked into a cylinder to combust and a gas after combustion is discharged. Such a series of devices is called an intake and exhaust device.

First, the intake apparatus is composed of an air cleaner for removing dust and the like in the air sucked into the cylinder, and an intake manifold for distributing the mixer to each cylinder.

And, as shown in Fig. 1, the exhaust device 10 includes an exhaust manifold 12 for synthesizing exhaust gas of each cylinder, an exhaust pipe 14 for exhausting exhaust gas into the atmosphere, and a silencer for reducing exhaust noise. (16) and a catalytic converter 18 which oxidizes and reduces harmful components in the exhaust gas without harm.

The catalytic converter 18 is installed in the middle of the exhaust pipe 14, and when passed through the exhaust pipe 14, harmful CO (carbon monoxide), HC (hydrocarbon), NO _X (nitrogen oxide) in the exhaust gas is harmless to CO ₂ (carbon dioxide), It is a device to oxidize and reduce with H ₂ O (water) and N ₂ (nitrogen).

The catalytic converter 18 has a pellet type and a monolith type in structure, and functionally, there are two types of an oxidation catalyst converter and a three-way catalytic converter.

Oxidation catalytic converter is a thin layer of noble metal of palladium (Pd) or palladium + platinum (Pt) that catalyzes the surface of granular alumina called catalytic pellets. Carbon monoxide and hydrocarbons in the exhaust gas are converted into carbon dioxide and water. Has the ability to make

The three-way catalytic converter uses noble metals, such as platinum + rhodium (Rh) or platinum + rhodium + palladium, which have a function of reducing carbon monoxide, hydrocarbons and nitrogen oxides in the exhaust gas. Three-way catalytic converters are currently the most used because of their high efficiency of more than%.

However, the three-way catalytic converter does not smoothly remove harmful components below a certain temperature before the catalyst is activated at the initial stage of the start of the automobile engine, and in particular, if the catalyst does not reach the specific activation temperature, the hydrocarbon is not purified. It has the disadvantage of discharging to heavy.

In addition, the three-way catalytic converter has a limit that can reduce harmful components (unburned hydrocarbons, carbon monoxide, nitrogen oxides, etc.) only when the air-fuel ratio is close to the theoretical air-fuel ratio. That is, there are disadvantages in that the purification of hydrocarbons and carbon monoxide components is drastically lowered in a rich fuel state, and the purification of nitrogen oxide components is drastically lowered when a large amount of air is contained.

To this end, in recent years, various studies have been conducted to reduce carbon dioxide emissions in order to improve fuel efficiency and reduce the green house effect.

As one of these studies, a technology related to a lean burn engine or a gasoline direct injection engine (GDI) has been proposed, but in this case, since a large amount of oxygen exists in the exhaust gas, a three-way catalyst is used. There is a disadvantage that can not be.

In other words, in the case of a lean burn engine or a gasoline direct injection engine, the air is operated in a state of considerable air richness, and thus, the exhaust gas contains more than 10% of oxygen and a large amount of nitrogen oxides under the lean burn combustion conditions. There is a limit in that the large amount of nitrogen oxide present in the gas cannot be sufficiently purified.

In particular, in the case of diesel engines, there is a problem that the purification performance of the exhaust gas is significantly reduced due to the large amount of nitrogen oxides and oxygen generated by the particulate material and the lean burn due to the use of lower fuel.

In order to solve this problem, recently, a nitrogen oxide reduction system and a nitrogen oxide adsorption system using a low temperature plasma have been used, and FIG. 2 shows an exhaust device 20 for reducing nitrogen oxide using only a low temperature plasma. .

As shown in FIG. 2, by supplying power to both sides of the plasma reactor 22 and passing the exhaust gas therein in a state where the inside of the plasma is ionized, the exhaust gas included in the exhaust gas is removed, and the harmful gas is removed. Is to reduce air pollution by exhausting to the atmosphere through the exhaust pipe (24).

That is, the power supply device 26 is connected to the plasma reactor 22, and the power supply device 26 selectively supplies power to the plasma reactor 22 by the controller 28. When power is applied to the plasma reactor 22, an ionization region is formed.

At the same time, an additive (for example, urea and unburned hydrocarbon) is supplied to the plasma reactor 22 by the additive supply device 30 to purify nitrogen oxide in an oxidizing atmosphere with high efficiency. In addition, the controller 32 serves to control the additive supply from the additive supply device 30, and the additive storage container 34 stores the additive.

However, the conventional exhaust gas exhaust system using only plasma reaction has a great effect on reducing hydrocarbons and nitrogen oxides in stationary internal combustion engines. However, since the electric power consumption is very large and the installation space needs to be increased, mobility is emphasized and vehicles with limited energy are available. It is not suitable for use.

In addition, in order to convert nitrogen oxide into high efficiency in an oxidizing atmosphere, additives such as urea and unburned hydrocarbons are required.These additives are easy to supply in stationary formula, but in the case of vehicles, an additional device for supplying additives must be installed. In addition to the above problems, it is difficult to secure space in the vehicle for installing the storage facility, and there is inconvenience in that the driver must continuously replenish the additives like fuel injection.

The present invention has been made to solve the above-mentioned problems, and by effectively purifying the unburned hydrocarbon components to reduce the pollution of the air pollution as well as to reduce the equipment cost for reducing air pollution emissions of a vehicle for reducing harmful emissions The purpose is to provide.

1 is a perspective view showing a general exhaust device,

2 is a configuration diagram showing an exhaust device using only a conventional plasma reaction;

3 is a block diagram showing an exhaust device according to an embodiment of the present invention,

** Description of symbols for the main parts of the drawing **

110: exhaust manifold 120: exhaust pipe

130: plasma reactor 140: power supply

150: engine control unit 160: photocatalytic reactor

170: three-way catalytic reactor

The present invention to achieve the above object is a plasma reactor installed in the middle of the exhaust pipe; A power supply for supplying power to the plasma reactor; An engine control unit controlling a power supply of the power supply; Located in the front of the plasma reactor, the photocatalyst reactor for purifying the nitrogen oxide component discharged with a large amount of oxygen in the exhaust gas in the oxidizing atmosphere and the unburned hydrocarbons, carbon monoxide in the exhaust gas located inside the plasma reactor It is characterized by including a three-way catalytic reactor to purify the components.

In the present invention, it is preferable that the photocatalytic reactor accommodates a noble metal (platinum, palladium) together with the photocatalyst to increase the purification efficiency therein.

In addition, it is preferable to accommodate the nitrogen oxide adsorber in the present invention to increase the purification efficiency in the photocatalytic reactor.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention;

3 is a block diagram showing a harmful gas reduction type exhaust apparatus according to an embodiment of the present invention. As shown in Figure 3, the harmful gas reduction type exhaust apparatus 100 of the present invention is a plasma reactor 130 is installed in the middle of the exhaust pipe 120; A power supply 140 for supplying power to the plasma reactor 130; An engine controller 150 for controlling a power supply of the power supply 140; Located in front of the inside of the plasma reactor 130, located in the rear of the photocatalytic reactor 160 and the inside of the plasma reactor 130 for purifying the nitrogen oxide component discharged with a large amount of oxygen in the exhaust gas in an oxidizing atmosphere And divided into three-way catalytic reactor 170 for purifying unburned hydrocarbons and carbon monoxide components in the exhaust gas.

That is, the exhaust gas generated inside the engine is collected in the exhaust manifold, and the collected exhaust gas is discharged into the atmosphere through the exhaust pipe 120, and in the middle of the exhaust pipe 120, harmful substances contained in the exhaust gas are removed. The plasma reactor 130 is installed to be able to.

The above-described plasma reactor 130 generates a plasma, which means that the plasma is electrically neutral to a region where ions and electrons exist at the same density.

When plasma is generated in the exhaust gas, free radicals are generated. Free radicals have a property that a chemical reaction of molecules is abundant due to cleavage of chemical bonds of molecules. Therefore, when free radicals, for example, OH, O ₃ , HO _2, etc., are generated in the exhaust gas, powerful oxidation is performed to reduce the hydrocarbon component in the exhaust gas.

Plasma reactors are already known in Korea Patent Publications 97-33051, 97-33050, 97-44278 and the like can be produced by these methods.

The plasma reactor 130 is connected to a power supply 140 for supplying power thereto, and the power supply 140 is connected to an engine control unit (ECU) 150 for controlling the power supply.

As a feature of the present invention, a photocatalytic reactor 160 is installed in front of the plasma reactor 130, and the photocatalysts reactor 160 is discharged together with a large amount of oxygen in the exhaust gas in an oxidizing atmosphere. It is intended to effectively purify the nitrogen oxide component. Various kinds of photocatalysts can be used, but TiO ₂ is most preferred. Photocatalyst (TiO ₂₎ is used which is excited by light of a characteristic wavelength, this process is TiO ₂ TiO ₂ (h +) + e−. TiO ₂ (h +) + e- is a highly reactive ionic body that excites H ₂ O or O 2 to accelerate and multiply the production of free radicals (a technique already known to those skilled in the art. Oxid.Technol Vol. 1, No. 1, 1996. p67-78p).

In addition, a three-way catalyst reactor 170 is installed inside the plasma reactor 130 adjacent to the photocatalytic reactor 160, and the three-way catalyst reactor 170 serves to purify unburned hydrocarbons and carbon monoxide in the exhaust gas. It is supposed to be.

Referring to the operation of the exhaust device of the harmful exhaust gas reducing vehicle according to an embodiment of the present invention configured as described above are as follows.

As shown in FIG. 3, power is supplied to the vehicle according to the start-up, and the engine controller 150 is operated. At the same time, the power supply 140 supplies power to the plasma reactor 130. As a result, plasma, which is an ionization region, is generated in the plasma reactor 130.

When plasma is generated, the plasma reaction region is enlarged by the photocatalyst, and free radical production is promoted. Nitrogen oxides passing through the exhaust pipe 120 by the abundantly produced free radicals are oxidized in an unstable state and are easily reduced by a small amount of reducing agent present in the exhaust gas.

On the other hand, in the case of purifying exhaust gas using only low-temperature plasma, O radicals and O ₃ radicals are mainly generated, but since they generate little OH radicals, they only promote the reaction of oxidizing NO or NO ₂ , reducing or reducing them. The reaction to HNO ₂ , HNO ₃ , which is advantageous, is very weak.

However, when the exhaust gas is purified using a photocatalyst, OH radicals are abundantly generated by the photocatalyst, and secondary OH radicals are abundantly generated by O ₂ radicals reacting with moisture. Therefore, as the OH radicals and the secondary OH radicals become rich, HNO ₂ and HNO ₃ are advantageously acting to increase the purification rate.

Therefore, the free radical state due to the excitation of the photocatalyst accelerates the reduction (reduction) action, thereby lowering the power consumption of the plasma reactor. As the photocatalyst generates a lot of free radicals, additives such as urea, which are required when only the plasma is used, are not required in the present invention, and power consumption is reduced.

Here, the addition of palladium (Pd), which is mainly involved in the reduction reaction of the three-way catalyst component, or the addition of a small amount of platinum (Pt) to the photocatalyst can further increase the oxidation and reduction reaction.

In this case, by adding a three-way catalyst (paradium, platinum, etc.) to the photocatalyst, the nitrate aerosol, which can be produced by the plasma reaction, can be treated to remove secondary pollutants as well as to be generated in the HC oxidation reaction. CO is reduced and HCO reaction is also involved to further improve the purification reaction.

In addition, by adding nitrogen oxide adsorber (NO _X Adsorber) a photocatalyst to remain on the catalyst for a longer time, the nitrogen oxide component is preferably sufficient to raise up the purification reaction. Unburned hydrocarbons and solid phase components which are not purified by the photocatalytic reaction are sufficiently purified by the three-way catalyst.

For reference, in the above-described plasma generation, heat of 600 ° C. to 700 ° C. is generated at the end of the plasma generator, and the noble metal catalyst is configured to purify the exhaust gas by heating the noble metal catalyst to a predetermined temperature as the generated heat. .

As a result, the nitrogen oxides in the exhaust gas, which are difficult to purify in the oxidizing atmosphere, are used to purify the photocatalyst, and the unburned hydrocarbons and carbon monoxide are purged by the three-way catalyst. It is possible to significantly reduce the gas.

The present invention is not limited to the above-described embodiments and can be carried out in various modifications within the range allowed by the technical idea of the present invention.

As described above, according to the present invention, by efficiently purifying nitrogen oxide, which is difficult to purify by the oxygen component present in the exhaust gas, with photocatalyst and three-way catalyst, the amount of carbon dioxide which is the main cause of global warming can be reduced as much as possible. It is effective to prevent.

In addition, the purification rate is excellent compared to the conventional system using only plasma, it can be aimed at high efficiency with low energy, the system is simplified to reduce the capacity of the power supply or the wire, etc., thereby reducing the installation cost.

In addition, the cumbersome, such as additive replenishment is eliminated, and by removing the additive storage device and the supply device there is an effect that can utilize the vehicle space as much.

Claims (3)

A plasma reactor installed in the middle of the exhaust pipe; A power supply for supplying power to the plasma reactor; An engine control unit controlling a power supply of the power supply; A photocatalytic reactor positioned in front of the plasma reactor and purifying nitrogen oxide components discharged with a large amount of oxygen in the exhaust gas in an oxidizing atmosphere; Located in the rear of the inside of the plasma reactor, the exhaust gas of the exhaust gas reducing vehicle comprising a three-way catalytic reactor for purifying the unburned hydrocarbons, carbon monoxide components in the exhaust gas. The exhaust system of claim 1, wherein the noble metal is stored together with the photocatalyst in the photocatalyst reactor. The exhaust system of claim 1 or 2, wherein a nitrogen oxide adsorber is accommodated in the photocatalytic reactor.