KR100368034B1 - Device for Reducing Diesel Exhaust Emission by Using Continuously Regenerative Plasma·Catalyst Hybrid System and method thereof - Google Patents

Abstract

The present invention can remove even fine particulate matter, less energy consumption, so as to increase the treatment efficiency by the catalyst,

A diesel oxidation catalyst unit 10 connected to an exhaust pipe of a diesel engine to oxidize NO in exhaust gas to NO ₂ ; A plasma reactor 20 which collects particulate matter in the exhaust gas passing through the diesel oxidation catalyst unit 10 by electrostatic action and reacts with NO ₂ converted in the diesel oxidation catalyst unit 10 to regenerate it; An apparatus and method for removing harmful substances in diesel engine exhaust gas using a plasma-catalyst combined continuous regeneration system, comprising a nitrogen oxide removal catalyst unit 30 which reduces and removes untreated nitrogen oxides in the plasma reactor 20. As,

By removing the soot using NO _2, which has high oxidizing power, it is possible to remove nitrogen oxide and particulate matter which have high treatment efficiency even at low temperature, and it was difficult to simultaneously reduce the combustion characteristics of diesel engine. There is an advantage that can be used continuously only in the present invention without a separate additional device for.

Description

Device for Reducing Diesel Exhaust Emission by Using Continuously Regenerative PlasmaCatalyst Hybrid System and method

The present invention relates to an apparatus and method for removing harmful substances from diesel engine exhaust gas using a plasma-catalyst continuous continuous regeneration system, and more particularly, to remove fine particulate matter by collecting particulate matter (PM) using a low temperature plasma reactor. The present invention relates to an apparatus and a method for removing harmful substances in diesel exhaust gas using a plasma / catalyst combined continuous regeneration system, in which energy consumption is lowered and a treatment efficiency by a catalyst is increased.

Most of the harmful substances emitted from diesel engines are particulate particulates and nitrogen oxides in dust state, and SCR, DPF, CRT and fuel additive methods are used as post-treatment methods to remove them. Problems such as the production of substances.

In the case of the particulate matter removal method using a filter which is one of the after-treatment methods of the diesel engine, in order to collect particulate matter by using a filter and additionally regenerate it, an electric heater, a diesel oil burner and a fuel additive, etc. Because of the need for the use of additional equipment needed to effectively remove particulate matter that is continuously discharged without regeneration, there is a problem that the cost is increased and the durability of the filter is not easy to maintain.

In addition, in the case of CRT, which is a continuous regeneration system composed of an oxidation catalyst and a filter, the oxidizing catalyst first oxidizes NO in the exhaust gas of a diesel engine to NO ₂ , and then reacts the highly oxidizing NO ₂ with particulate matter trapped in the filter. To reduce the particulate matter at the same time, since a filter is used to capture the particulate matter, it is possible to collect relatively large particulate matter, but in the case of fine particulate matter, it is difficult to collect.

Therefore, in this case, even if NO ₂ is generated from the oxidation catalyst, the particles must react with the large particulate matter, and the actual experimental results show that the particulate matter reduction rate is very high while the NOx reduction rate is very low.

In addition, in the case of a post-treatment apparatus using a conventional plasma-catalyst combined continuous regeneration system other than a method using a filter, a plasma apparatus is used for the purpose of generating NO ₂ , or an exhaust gas is reduced only by using a plasma apparatus. The energy required to generate NO ₂ or remove NO x was rather unreasonable for practical diesel engines.

The present invention is a method for solving the problems as described above, it is easy to remove even fine particulate matter to increase the efficiency of processing of particulate matter, the apparatus for removing harmful substances in diesel engine exhaust gas using a plasma-catalyst combined continuous regeneration system And to provide a method.

Another object of the present invention is to provide an apparatus and method for removing harmful substances from diesel engine exhaust gas using a plasma / catalyst combined continuous regeneration system that can significantly reduce energy required for diesel exhaust gas treatment.

Still another object of the present invention is to remove harmful substances in diesel engine exhaust gas and to continuously regenerate particulate matter using a plasma-catalyst combined continuous regeneration system capable of simultaneously removing particulate matter and nitrogen oxides in diesel engine exhaust gas. To provide a way.

The above object of the present invention is a diesel oxidation catalyst (DOC) unit for oxidizing NO in exhaust gas to NO ₂ , a plasma reactor for collecting and removing particulate matter in exhaust gas, and untreated nitrogen oxides. A nitrogen oxide removal catalyst (DeNOx catalyst) which is reduced and removed is achieved by providing a device for removing harmful substances of diesel engine exhaust gas using a plasma-catalyst combined continuous regeneration system. As a result, it is easy to collect and remove fine particulate matter, and because plasma is used only for collecting particulate matter, the energy consumption is very low, and the particulate matter can be continuously reduced with only this system without any additional equipment.

1A is a schematic diagram of a removal device according to an embodiment of the present invention;

1B is a configuration diagram of the same,

Figure 2a is a comparison table of the concentration distribution of carbon monoxide, nitrogen monoxide, nitrogen dioxide at 230 ℃,

Figure 2b is a comparison table of the concentration distribution of carbon monoxide, nitrogen monoxide, nitrogen dioxide at 280 ℃,

Figure 2c is a comparison table of the concentration distribution of carbon monoxide, nitrogen monoxide, nitrogen dioxide at 330 ℃,

3A is a schematic diagram of a removal device according to another embodiment of the present invention;

3B is the same configuration diagram.

Explanation of symbols on the main parts of the drawings

10: diesel oxidation catalyst

20: plasma reactor

30: nitrogen oxide removal catalyst

30 ': catalyst filter

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a diesel oxidation catalyst (DOC) unit 10 connected to an exhaust pipe of a diesel engine and oxidizing NO in exhaust gas to NO ₂ is provided; A plasma reactor 20 which collects particulate matter in the exhaust gas passing through the diesel oxidation catalyst unit 10 by electrostatic action and reacts with NO ₂ converted in the diesel oxidation catalyst unit 10 to regenerate it; It is composed of a nitrogen oxide removal catalyst unit 30 for reducing and removing nitrogen oxides such as NO ₂ , NO, etc. that could not be removed in the plasma reactor 20.

In the present invention, the path through which the exhaust gas flows is a sequence of a diesel engine → an oxidation catalyst unit 10 → a plasma reactor 20 → a nitrogen oxide removal catalyst unit 30 or before the exhaust gas enters the oxidation catalyst unit 10. It is preferable to make the temperature of the nitrogen oxide removal catalyst part 30 high so that the temperature of the oxidation catalyst part 10 may be made to heat-exchange with the nitrogen oxide removal catalyst part 30.

In addition, a diesel oxidation catalyst and a nitrogen oxide removal catalyst are generally catalyst components composed of a porous high surface area carrier such as alumina, precious metals such as platinum (Pt), rhodium (Rh), and palladium (Pd) and various additives. The honeycomb-shaped ceramic is coated in many forms, but is not particularly limited in the practice of the present invention can be used as is the catalyst generally used as it is.

In addition, in order to increase the treatment efficiency of the removal device of the present invention, a catalyst capable of complementary action with the dust collecting action of the plasma reactor may be used. In the case of the diesel oxidation catalyst, the low temperature activity of the oxidation catalyst and the poisoning of water and sulfur In order to improve the performance, platinum is used as the main catalyst 10-100 g / ft3 and at least one platinum selected from the group consisting of vanadium (V), chromium (Cr), strontium (Sr) and manganese (Mn) as a promoter It is preferred to use 2 to 10 times the amount.

Looking at the process of removing harmful substances in the diesel engine exhaust gas according to the present invention configured as described above are as follows.

The present invention includes the steps of injecting the exhaust gas discharged from the diesel engine into the diesel oxidation catalyst unit 10 to oxidize NO in the exhaust gas to NO ₂ ; The exhaust gas passing through the diesel oxidation catalyst unit 10 is introduced into the plasma reactor 20 to collect fine particulate matter by electrostatic action and to react with the NO ₂ converted in the diesel oxidation catalyst unit 10 to be regenerated. Wow; Removing the untreated nitrogen oxide in the plasma reactor 20 in the nitrogen oxide removal catalyst unit 30 is configured.

First, the exhaust gas discharged from the diesel engine is heat-exchanged with the nitrogen oxide removal catalyst unit 30 in order to increase the catalytic activity before entering the diesel oxidation catalyst unit 10, and then flows into the diesel oxidation catalyst unit 10. At this time, NO in the exhaust gas is converted into NO ₂ by the oxidation reaction in the catalyst as shown in the following reaction formula.

At this time, soluble organic matter (SOF), which is a component of particulate matter, and hydrocarbon (HC) and carbon monoxide (CO) in exhaust gas are also partially oxidized.

Next, the exhaust gas passing through the diesel oxidation catalyst unit 10 passes through the plasma reactor 20. Particulate matter in the exhaust gas is attached to the dust collecting plate by the electrostatic action of the plasma and is collected inside the reactor.

In the present invention, since the plasma reactor 20 is used only for the collection of particulate matter, the energy consumption is low, and thus, the plasma reactor 20 may be applied to various vehicles equipped with diesel engines of various sizes.

That is, the plasma reactor 20 is provided with a power supply connected to the engine control unit, when the power is supplied to the vehicle as the vehicle is turned on, the engine control unit is activated and the power supply supplies power to the plasma reactor 20 The plasma will be generated.

In addition, when particulate matter is collected using a filter, relatively large particles are collected because of the size of the filter pores, and deterioration may occur because the filter is made of ceramic when the back pressure is applied or the regeneration time is long. However, in the present invention, since the electrostatic precipitating principle of the plasma is used, fine particulate matter is collected, and since the material of the dust collecting plate is made of stainless special use stainless steel (SUS), there is no fear of deterioration and back pressure, so that continuous regeneration is possible without additional equipment. It is possible.

The particulate matter collected inside the plasma reactor 20 causes a reaction shown in the following reaction formula with NO ₂ converted in the diesel oxidation catalyst 10 and is oxidized at a relatively low temperature of about 220 ° C.

Generally, soot in diesel exhaust gas is oxidized at a high temperature of 650 ° C. or higher, but is oxidized at a lower temperature than when reacted with NO ₂ having a high oxidizing power. Therefore, in the present invention, by removing the soot using NO ₂ , the treatment efficiency is high even at a low temperature.

As described above, the plasma reactor 20 continuously collects and regenerates particulate matter, and the plasma itself converts a small amount of NO into NO ₂ to assist the activity of the diesel oxidation catalyst.

In addition, since the smaller the size of the particulate matter, the reaction with NO ₂ generated in the oxidation catalyst unit 10 occurs more easily, and thus the effect of simultaneously reducing the particulate matter and the nitrogen oxide of the present invention is very excellent.

2A to 2C illustrate the original exhaust gas, the exhaust gas passing through the oxidation catalyst, the exhaust gas passing through the plasma reactor, and the exhaust gas passing through the oxidation catalyst unit 10 and the plasma reactor 20 according to the present invention. In comparison, the concentration distributions of carbon monoxide, nitrogen monoxide and nitrogen dioxide are shown.

As shown in FIGS. 2A to 2C, although the temperature is somewhat different, in the present invention including the oxidation catalyst unit 10 and the plasma reactor 20, NO is oxidized to NO ₂ so that the plasma reactor 20 may be used. As it was removed through the process, about 30-40% of the total NOx was removed, and almost 100% of the particulate matter was removed, which is similar to that of the original exhaust gas, the exhaust gas passed through the oxidation catalyst, and the exhaust gas passed through the plasma reactor. In comparison, the processing efficiency is relatively very high.

Meanwhile, the untreated NO ₂ and NO after the oxidation reaction with the particulate matter in the plasma reactor 20 pass through the nitrogen oxide removal catalyst unit 30 formed by coating a catalyst on a support of a flow through method. It is removed by the reduction reaction shown in the following scheme.

Although a reducing agent may be added from the outside for the reduction reaction, a reducing agent such as hydrocarbon (HC), carbon monoxide (CO), and soot in the exhaust gas may be used.

In addition, in the practice of the present invention, in order to increase the treatment efficiency of particles having large particles, a catalyst in which the nitrogen oxide removal catalyst is coated on a wall flow filter as shown in FIGS. 3A and 3B is preferable. Filter 30 'can be used.

That is, when only the nitrogen oxide removal catalyst is used, untreated NO ₂ and NO may be removed from the plasma reactor 20, but the catalyst filter 30 'is used by using the catalyst filter 30' coated on the filter. Large particles in the particles are collected and reacted with untreated nitrogen oxide in contact with the catalyst to remove both components at the same time.

At this time, since the particulate matter having a relatively large particle is collected in the catalyst filter 30 ', not only the back pressure is reduced, but also the reaction time between the particulate matter and the untreated NO ₂ is sufficient to be effectively regenerated.

When the nitrogen oxide removal catalyst is coated on the filter, a catalyst precursor is prepared in the form of an aqueous solution so as to uniformly coat the main catalyst on the filter, followed by dry sintering.

The apparatus and method for removing harmful substances in the diesel engine exhaust gas according to the present invention, which is configured and functioned as described above, is more efficient than the conventional system in collecting and removing fine particulate matter and using plasma only for collecting particulate matter. Very low consumption

In fact, the conventional method of removing using a plasma reactor consumes about 10 wh / m3 of energy to remove 50% of NOx because of using ions, whereas the present invention uses about electrons, so about 0.2-2 wh / m 3 may be required. It is only about 80W, which is the power of one headlight.

In addition, the present invention removes soot using NO ₂ having high oxidizing power, and thus it is possible to simultaneously remove nitrogen oxide and particulate matter, which are difficult to simultaneously reduce due to combustion characteristics of diesel engine, and to reduce particulate matter. There is an advantage that can be used continuously only in the present invention without a separate additional device for regeneration.

In addition, the present invention has an advantage that it is easy to apply to a variety of vehicles equipped with a diesel engine of various sizes using a vehicle power supply device because the configuration is simple and less energy consumption.

Claims (8)

A diesel oxidation catalyst unit 10 connected to an exhaust pipe of a diesel engine to oxidize NO in exhaust gas to NO ₂ ; A plasma reactor 20 which collects particulate matter in the exhaust gas passing through the diesel oxidation catalyst unit 10 by electrostatic action and reacts with NO ₂ converted in the diesel oxidation catalyst unit 10 to regenerate it; An apparatus for removing harmful substances in diesel engine exhaust gas using a plasma / catalyst combined continuous regeneration system, comprising a nitrogen oxide removal catalyst unit (30) for reducing and removing untreated nitrogen oxides in the plasma reactor (20). The apparatus of claim 1, wherein the nitrogen oxide removal catalyst is coated on a support of a flow through method and used to remove harmful substances in the diesel engine exhaust gas using a plasma / catalyst combined continuous regeneration system. . The apparatus of claim 1, wherein the nitrogen oxide removal catalyst is coated and used on a wall flow filter. The diesel oxidation catalyst according to any one of claims 1 to 3, wherein platinum is used at a concentration of 10 to 100 g / ft3 as a main catalyst, and vanadium (V), chromium (Cr), strontium (Sr), and manganese are used as cocatalysts. At least one selected from the group consisting of (Mn) is used to remove harmful substances in diesel engine exhaust gas using a plasma-catalyst combined continuous regeneration system, characterized in that 2 to 10 times the amount of platinum. Injecting the exhaust gas discharged from the diesel engine into the diesel oxidation catalyst unit 10 to oxidize NO in the exhaust gas to NO ₂ ; The exhaust gas passing through the diesel oxidation catalyst unit 10 is introduced into the plasma reactor 20 to collect fine particulate matter by electrostatic action and to react with the NO ₂ converted in the diesel oxidation catalyst unit 10 to be regenerated. Wow; Removing the untreated nitrogen oxide in the plasma reactor 20 in the nitrogen oxide removal catalyst unit 30, the method of removing harmful substances in the diesel engine exhaust gas using a plasma-catalyst combined continuous regeneration system. The method of claim 5, wherein the exhaust gas discharged from the diesel engine is further heat-exchanged with the nitrogen oxide removal catalyst unit 30 before entering the oxidation catalyst unit 10, plasma-catalyst complex Method for removing harmful substances in diesel engine exhaust gas using continuous regeneration system. The method according to claim 5 or 6, wherein the nitrogen oxide removal catalyst is coated on a wall flow filter to collect particulate matter having a large particle in the catalyst filter 30 ', and then, in the plasma reactor 20, A method of removing harmful substances in a diesel engine exhaust gas using a plasma / catalyst combined continuous regeneration system, characterized in that both components are removed simultaneously by reacting with an untreated nitrogen oxide. The diesel oxidation catalyst according to any one of claims 5 to 7, wherein platinum is used as a main catalyst at 10 to 100 g / ft3, and vanadium (V), chromium (Cr), strontium (Sr), and manganese as cocatalysts. A method for removing harmful substances in diesel engine exhaust gas using a plasma-catalyst combined continuous regeneration system, wherein at least one selected from the group consisting of (Mn) is used at 2 to 10 times the amount of platinum.