KR101022018B1 - Exhaust gas purification system of engine and marine engine with the same - Google Patents

Abstract

PURPOSE: An exhaust gas purification system for an engine and an engine for a ship are provided to prevent the poisoning phenomenon of oxidation catalyst and to treat harmful contents at high efficiency. CONSTITUTION: An exhaust gas purification system for an engine comprises a combustion chamber(11), a precious metal catalyst, and an oxidation catalyst. The combustion chamber connects to a pressure unit(131) of a turbocharger(13) through an intake manifold(12). The combustion chamber receives the pressurized air. The combustion chamber connects to a turbine part(132) of the turbocharger through an exhaust manifold(15). The combustion chamber discharges the exhaust gas after the reaction of combustion. The precious metal catalyst is installed inside the exhaust manifold. The carrier and the surface of the carrier are coated with the precious metal catalyst. The oxidation catalyst oxidizes hydrocarbon, carbon monoxide, and nitrogen oxide in the exhaust gas.

Description

Exhaust gas purification system of engines and marine engines including the same {EXHAUST GAS PURIFICATION SYSTEM OF ENGINE AND MARINE ENGINE WITH THE SAME}

The present invention relates to an exhaust gas purification system of an engine, and more particularly, to an exhaust gas purification system that can be applied to a marine engine using a fuel having a high sulfur content.

The oxidation catalyst oxidizes hydrocarbons (HC) and carbon monoxide (CO) in exhaust gases emitted from diesel engines or gasoline engines, and oxidizes nitrogen monoxide (NO) in nitrogen oxides (NOx) to nitrogen dioxide (NO ₂ ). . The oxidation catalyst is composed of a carrier made of ceramic honeycomb or the like and a noble metal catalyst such as platinum (Pt), rhodium (Rh), and palladium (Pd) coated with a washcoat on the surface of the carrier.

Conventional oxidation catalysts are installed at the rear of the turbine section of the turbocharger in order not to affect the output of the engine. However, in the case of a marine engine using a fuel having a high sulfur content, the temperature of the exhaust gas is 350 ° C or lower. At this temperature, the sulfur component is adsorbed on the washcoat portion of the oxidation catalyst, which hinders the action of the noble metal catalyst, causing poisoning and degrading the function of the oxidation catalyst.

When the function of the oxidation catalyst is reduced, even if the nitrogen oxide reduction device is installed, the reduction reaction occurring in the reduction catalyst in the nitrogen oxide reduction device is very slow since most of the nitrogen oxide is nitrogen monoxide (NO). Therefore, in order to obtain high conversion efficiency, the method of lowering the space velocity is the only method, but in this case, the volume of the reduction catalyst increases, thereby increasing the space constraint.

The present invention provides an exhaust gas purification system of an engine capable of treating poisonous components contained in exhaust gas with high efficiency by preventing poisoning of an oxidation catalyst in an engine using a fuel having a high sulfur content, and a marine engine including the same. I would like to.

Exhaust gas purification system of the engine according to an embodiment of the present invention is connected to the compression portion of the turbocharger through the intake manifold to receive the pressurized air and connected to the turbine portion of the turbocharger through the exhaust manifold exhaust generated after the combustion reaction An engine comprising a plurality of combustion chambers for discharging gas, comprising an oxidation catalyst installed in the exhaust manifold and oxidizing hydrocarbons, carbon monoxide and nitrogen monoxide in the exhaust gas, including a catalyst and a noble metal catalyst coated on the surface of the carrier. do.

The exhaust manifold includes a plurality of branch pipes connected to each of the plurality of combustion chambers and an exhaust pipe connected to the plurality of branch pipes, and the oxidation catalyst may be formed to be in close contact with the inner wall of the exhaust pipe and face the plurality of branch pipes. The oxidation catalyst may be formed to a length greater than the distance between the outermost branch pipes of the plurality of branch pipes plus two times the diameter of the branch pipes.

The oxidation catalyst may be divided into a plurality of spaced apart from each other in the exhaust pipe. The exhaust pipe is connected to the turbine portion via the neck pipe, and the plurality of oxidation catalysts may be located in the region between the plurality of branch pipes and in the region between the outermost branch pipe and the neck pipe. In the plurality of oxidation catalysts, at least one of the cell density and the pore size of the carrier may be formed differently depending on the position. As the oxidation catalyst is closer to the turbine portion among the plurality of oxidation catalysts, the carrier may have a low cell density or form large pores.

Of the plurality of oxidation catalysts, an oxidation catalyst closer to the turbine part may have a larger cross-sectional area. The exhaust pipe includes a plurality of regions surrounding the oxidation catalyst, and the plurality of regions may have a larger diameter as they are closer to the turbine portion. In the plurality of oxidation catalysts, at least one of the cell density and the pore size of the carrier may be formed differently depending on the position. As the oxidation catalyst is closer to the turbine portion among the plurality of oxidation catalysts, the carrier may have a low cell density or form large pores.

The oxidation catalyst may be divided into a plurality, and the plurality of oxidation catalysts may be located inside the plurality of branch pipes. The plurality of oxidation catalysts may be formed to have the same cell density and pore size of the carrier.

The carrier is formed from one or more of a foam made of ceramic or metal, a thin metal laminate, and a metal wire molded body, and the precious metal catalyst comprises at least one of platinum, rhodium, and palladium and is coated on the surface of the carrier with a washcoat. Can be.

The exhaust gas purification system of the engine further includes a nitrogen oxide reduction device installed in an exhaust pipe at the rear end of the turbine part, and the nitrogen oxide reduction device includes a catalyst part of a selective catalyst reduction method and an injector for injecting a reducing agent from the front end of the catalyst part toward the catalyst part. It may include.

Marine engine according to an embodiment of the present invention includes an exhaust gas purification system of the above-described structure. The marine engine may further include a nitrogen oxide reduction device installed in an exhaust pipe at the rear end of the turbine part, and the nitrogen oxide reduction device may include a catalyst part of a selective catalyst reduction method and an injector for injecting a reducing agent from the front end of the catalyst part toward the catalyst part. .

According to embodiments of the present invention, in a marine engine using a fuel having a high sulfur content, by installing the oxidation catalyst in front of the turbine section of the turbocharger, it is possible to prevent poisoning of the oxidation catalyst and to remove harmful components contained in the exhaust gas with high efficiency. Can be treated as Such an oxidation catalyst speeds up the reaction rate of the nitrogen oxide reduction device installed at the rear of the turbine unit, thereby improving the purification performance of the nitrogen oxide reduction device.

1 is a schematic diagram showing an exhaust gas purification system of an engine according to a first embodiment of the present invention.
2 is a schematic diagram showing an exhaust gas purification system of an engine according to a second embodiment of the present invention.
3 is a schematic diagram showing an exhaust gas purification system of an engine according to a third embodiment of the present invention.
4 is a schematic diagram showing an exhaust gas purification system of an engine according to a fourth embodiment of the present invention.
5 is a schematic diagram showing an exhaust gas purification system of an engine according to a fifth embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a schematic diagram showing an exhaust gas purification system of an engine according to a first embodiment of the present invention.

Referring to FIG. 1, the engine 10 includes a plurality of combustion chambers 11 that generate power by burning fuel and compressed air. Each of the plurality of combustion chambers 11 is connected to the compression unit 131 and the air purifier 14 of the turbocharger 13 through the intake manifold 12. In addition, each of the plurality of combustion chambers 11 is connected to the turbine portion 132 of the turbocharger 13 through an exhaust branch pipe 15.

The intake air is purified through the air purifier 14 and pressurized while passing through an impeller (not shown) provided in the compression section 131 of the turbocharger 13. Pressurized intake air is supplied to the combustion chamber 11 wall surface through the intake manifold 12. After combustion, the exhaust gas is discharged to the exhaust manifold 15 through a poppet valve (not shown) installed above the engine 10, and the turbine (not shown) installed in the turbine portion 132 of the turbocharger 13 is discharged. Driven and discharged to the discharge pipe (16).

The turbocharger 13 has a rotating shaft 133 connecting the impeller and the turbine to transfer the power of the turbine generated by the exhaust gas to the impeller.

The engine 10 of the above-described configuration may be a marine engine using fuel having a high sulfur content. Marine engines consist of a two-stroke system for large and four-stroke systems for small and medium. In the case of a two-stroke engine, pressurized intake air is compressed and ignited by fuel injection in the compression process, and proceeds to the expansion process.

The exhaust gas purification system 100 of the first embodiment includes an oxidation catalyst 171 and a nitrogen oxide reduction device 18. The oxidation catalyst 171 is not located at the rear end of the turbine portion 132 of the turbocharger 13, and the exhaust manifold 15 is formed inside the exhaust manifold 15 connecting the combustion chamber 11 and the turbine portion 132. Position to fill. The nitrogen oxide reduction device 17 is located at the rear end of the turbine portion 132 of the turbocharger 13.

The oxidation catalyst 171 is composed of a carrier having a plurality of pores and a noble metal catalyst coated with a washcoat on the surface of the carrier. The carrier may be formed from one or more of a foam made of ceramic or metal such as cordierite, silicon carbide (SiC), and aluminum titanite, a thin metal laminate, and a metal wire molded body. The noble metal catalyst includes at least one of platinum (Pt), rhodium (Rh), and palladium (Pd).

The oxidation catalyst 171 oxidizes hydrocarbon (HC) and carbon monoxide (CO) in exhaust gas by oxidation / reduction reaction of a noble metal catalyst, and oxidizes nitrogen monoxide (NO) in nitrogen oxide (NOx) to nitrogen dioxide (NO ₂ ). By this, the exhaust gas is first purified.

In the case of large ship engines, the speed of the doubled gas is lower than that of the four-stroke engines that rotate at high speed because the engine rotates at a low speed of 130 rpm or less and performs two-stroke combustion. Although there are differences depending on the size and operating conditions of the engine 10, the temperature of the exhaust gas discharged through the turbine unit 132 of the turbocharger 13 is approximately 190 ° C to 240 ° C in the case of the large two-stroke engine described above.

If the oxidation catalyst 171 is provided at the rear end of the turbine portion 132 of the turbocharger 13, it is difficult to avoid poisoning due to the sulfur component of the fuel due to the low temperature of the exhaust gas. However, in this embodiment, since the oxidation catalyst 171 is installed inside the exhaust manifold 15 maintaining the temperature of 400 ° C to 450 ° C on average, poisoning by sulfur components can be effectively prevented.

The exhaust manifold 15 includes a plurality of branch pipes 151 connected to each of the plurality of combustion chambers 11, and an exhaust pipe 152 connected to the plurality of branch pipes 151. The oxidation catalyst 171 is in close contact with the inner wall of the exhaust pipe 152 and is formed to have a length facing all of the plurality of branch pipes 151. That is, the oxidation catalyst 171 has a length larger than the distance d1 between the outermost branch pipes 151 of the plurality of branch pipes 151 plus twice the diameter d2 of the branch pipes 151 ( L).

Then, the exhaust gas discharged to the plurality of branch pipes 151 passes through the oxidation catalyst 171 before entering the turbine unit 132 of the turbocharger 13 from the initial time of joining the exhaust pipe 152, so that the exhaust gas and The contact area of the oxidation catalyst 171 can be enlarged to increase the decomposition efficiency of the exhaust gas.

On the other hand, since the exhaust manifold 15 is a passage through which exhaust gas used for combustion is discharged, a pressure loss may occur due to the carrier of the oxidation catalyst 171, thereby reducing the efficiency of the turbocharger 13. In consideration of this, the carrier of the oxidation catalyst 171 of the present embodiment may be made of a metal having a low heat capacity, and may have a pore size in the range of several hundred micrometers (μm) to several millimeters (mm).

Therefore, the oxidation catalyst 171 of the present embodiment can minimize the pressure loss and increase the conversion efficiency of the exhaust gas without causing the output of the turbocharger 13 to effectively oxidize harmful components of the exhaust gas.

The nitrogen oxide reduction device 18 is installed in the discharge pipe 16 to drive the turbine unit 132 of the turbocharger 13 and receive the discharged exhaust gas. The tail discharge pipe 19 is located at the rear end of the nitrogen oxide reduction device 18 to discharge the exhaust gas passed through the nitrogen oxide reduction device 18 to the atmosphere.

The nitrogen oxide reduction device 18 may be a selective catalytic reduction (SCR) method. The nitrogen oxide reduction device 18 includes a catalyst unit 181 and an injector 182 positioned at the front end of the catalyst unit 181 and injecting a reducing agent toward the catalyst unit 181. The reducing agent may be an aqueous solution of ammonia (NH ₃ ) or an aqueous solution of urea (NH ₂ CONH ₂ ), and in the case of the aqueous solution of urea, the injected urea is decomposed to generate ammonia.

The nitrogen oxide reduction device 18 reduces the nitrogen oxides in the exhaust gas by reducing the nitrogen oxides (NOx) in the exhaust gas to nitrogen (N ₂ ) by mixing and reacting the hot exhaust gas and the reducing agent with each other in the catalyst unit 181. Let's do it.

In the present embodiment, since the oxidation catalyst 171 is installed inside the high temperature exhaust pipe 152, nitrogen monoxide (NO) is oxidized to nitrogen dioxide (NO ₂ ) with high efficiency without poisoning of the carrier. Therefore, since nitrogen monoxide (NO) in the exhaust gas that has passed through the turbine portion 132 of the turbocharger 13 has a low concentration, the reaction rate of the nitrogen oxide reduction device 18 is increased to purify the catalytic portion 181. To improve.

Furthermore, since nitrogen dioxide (NO ₂ ) generated by the oxidation catalyst 171 makes the reduction reaction of the catalyst portion 181 advantageous, the size of the catalyst portion 181 can be reduced. As a result, the nitrogen oxide reduction device 18 can obtain a high conversion efficiency even when the catalyst portion 181 is manufactured in a small size, and the space constraint is reduced.

In addition, the oxidation catalyst 171 also has a function of collecting particulate matter discharged from the engine 10. Particulate matter discharged from the engine 10 includes soluble organic fraction (SOF), volatile solid carbon and ash, sulfur sulfate, and the like. have. Among these, the soluble organic material (SOF) is mostly oxidized and removed under oxidation catalyst conditions, and the fixed carbon powder is partially removed by flow while passing through the oxidation catalyst 171.

2 is a schematic diagram showing an exhaust gas purification system of an engine according to a second embodiment of the present invention.

Referring to FIG. 2, the exhaust gas purification system 200 of the second embodiment includes the oxidation catalyst 172 divided into a plurality and disposed at a distance from each other in the exhaust pipe 152. It has the same configuration as the exhaust gas purification system 100. The same reference numerals are used for the same members as in the first embodiment.

The plurality of oxidation catalysts 172 are located in a region of the exhaust pipe 152 that does not face the branch pipe 151. That is, the plurality of oxidation catalysts 172 are located in the region between the branch pipes 151 and the region between the outermost branch pipe 151 and the neck pipe 20 among the exhaust pipe 15. In FIG. 2, the left three oxidation catalysts 172 are positioned in the region between the branch pipes 151 of the exhaust pipe 152, and the right one oxidation catalyst 172 is the outermost branch pipe 151 and the neck pipe 20. The case where it is located in the area between is shown as an example.

The neck pipe 20 refers to a bent pipe connecting the exhaust pipe 152 and the turbine portion 132 of the turbocharger 13. In the second embodiment, by dividing the plurality of oxidation catalysts 172 between the branch pipes 151, when the exhaust gas is discharged from the combustion chamber 11 of the engine 10, the back pressure may be relaxed.

3 is a schematic diagram showing an exhaust gas purification system of an engine according to a third embodiment of the present invention.

Referring to FIG. 3, the exhaust gas purification system 300 of the third embodiment exhausts the exhaust gas of the above-described second embodiment except for a structure in which at least one of the cell density and the pore size of the carrier varies according to the position of the oxidation catalyst 173. It has the same configuration as the gas purification system 200. The same reference numerals are used for the same members as in the second embodiment.

The exhaust pipe 152 connected to the plurality of branch pipes 151 may increase in the back pressure as the amount of the exhaust gas increases toward the rear end, that is, the closer to the turbine unit 132. In consideration of this, in the third embodiment, the oxidation catalyst 173 closer to the turbine unit 132 among the plurality of oxidation catalysts 173 disposed in a split arrangement has a structure in which the cell density of the carrier is reduced or the pore size of the carrier is increased. Can be reduced.

4 is a schematic diagram showing an exhaust gas purification system of an engine according to a fourth embodiment of the present invention.

Referring to FIG. 4, the exhaust gas purification system 400 of the fourth embodiment is the second embodiment described above except for the structure in which the oxidation catalyst 174 closer to the turbine portion 132 of the turbocharger 13 is larger. Or the same configuration as the exhaust gas purification system of the third embodiment. The same reference numerals are used for the same members as in the second embodiment.

The cross-sectional area of the oxidation catalyst 174 refers to the size of the cross section perpendicular to the inflow direction of the exhaust gas, and may also be defined as the size or diameter of the oxidation catalyst 174 measured in the direction perpendicular to the inflow direction of the exhaust gas. have.

The plurality of oxidation catalysts 174 may be configured in the same cell density and pore size of the carrier, or at least one of the cell density and the pore size may be different. For example, the plurality of oxidation catalysts 174 may be formed in a structure in which the cell density of the carrier is lower or the pore size of the carrier is larger as it is located closer to the turbine unit 132.

The exhaust pipe 152 includes a plurality of regions surrounding the plurality of oxidation catalysts 174, and the plurality of regions are formed to have a larger diameter toward the turbine portion 132 to change the cross-sectional area of the oxidation catalyst 174.

In the fourth embodiment, it is possible to reduce the back pressure of the exhaust gas and to improve the conversion efficiency of the oxidation catalyst 174 by keeping the space velocity of the exhaust gas passing through the plurality of oxidation catalysts 174 constant.

5 is a schematic diagram showing an exhaust gas purification system of an engine according to a fifth embodiment of the present invention.

Referring to FIG. 5, the exhaust gas purifying system 500 of the fifth embodiment is the second embodiment described above except for the structure in which the plurality of oxidation catalysts 175 are located in the plurality of branch pipes 151 instead of the exhaust pipe 152. The same configuration as the exhaust gas purification system 200 of the example. The same reference numerals are used for the same members as in the second embodiment.

In the fifth embodiment, since it is not necessary to consider the change in the exhaust flow rate according to the position of the exhaust pipe 152, the oxidation catalyst 175 of the same size and the same specification can be used to facilitate the installation and replacement of the oxidation catalyst 175. Can be.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

100, 200, 300, 400, 500: exhaust gas purification system
10: engine 11: combustion chamber
12: intake manifold 13: turbocharger
131: compression unit 132: turbine unit
133: shaft 14: air purifier
15: exhaust manifold 151: branch pipe
152: exhaust pipe 16: exhaust pipe
171, 172, 173, 174, 175: oxidation catalyst
18: nitrogen oxide reduction device 181: catalyst unit
182: injector 19: tail discharge pipe
20: neck pipe

Claims (17)

Purification of exhaust gas of an engine including a plurality of combustion chambers connected to the compression section of the turbocharger through an intake manifold to receive pressurized air, and connected to the turbine section of the turbocharger through an exhaust manifold to discharge exhaust gases generated after the combustion reaction. In the system,
An exhaust gas purification system of an engine installed in the exhaust manifold and including an oxidizing catalyst for oxidizing hydrocarbon and carbon monoxide and nitrogen monoxide in exhaust gas, including a carrier and a noble metal catalyst coated on the surface of the carrier. The method of claim 1,
The exhaust manifold includes a plurality of branch pipes connected to the plurality of combustion chambers and an exhaust pipe connected to the plurality of branch pipes,
And the oxidation catalyst is in close contact with an inner wall of the exhaust pipe and formed to have a length facing the plurality of branch pipes. The method of claim 2,
And the oxidation catalyst has a length greater than the distance between the outermost branch pipes of the plurality of branch pipes plus two times the diameter of the branch pipes. The method of claim 1,
The exhaust manifold includes a plurality of branch pipes connected to the plurality of combustion chambers and an exhaust pipe connected to the plurality of branch pipes,
The oxidation catalyst is an exhaust gas purification system of an engine is arranged in a plurality of spaced apart from each other inside the exhaust pipe. The method of claim 4, wherein
The exhaust pipe is connected to the turbine portion through a neck pipe,
And the plurality of oxidation catalysts are located in the region between the plurality of branch pipes and in the region between the outermost branch pipe and the neck pipe. The method of claim 5,
And the plurality of oxidation catalysts are formed at least one of a cell density and a pore size of the carrier according to a position. The method of claim 6,
The exhaust gas purification system of an engine in which the carrier has a lower cell density or forms larger pores as the oxidation catalyst closer to the turbine part among the plurality of oxidation catalysts. The method of claim 5,
The exhaust gas purification system of the engine which has a larger cross-sectional area as the oxidation catalyst closer to the said turbine part among the said several oxidation catalysts. The method of claim 8,
The exhaust pipe includes a plurality of regions surrounding the oxidation catalyst, and the plurality of regions have a larger diameter as the turbine portion is closer to the turbine portion. 10. The method of claim 9,
And the plurality of oxidation catalysts are formed at least one of a cell density and a pore size of the carrier according to a position. The method of claim 10,
The exhaust gas purification system of an engine in which the carrier has a lower cell density or forms larger pores as the oxidation catalyst closer to the turbine part among the plurality of oxidation catalysts. The method of claim 1,
The oxidation catalyst is divided into a plurality, the plurality of oxidation catalysts are located in the plurality of branch pipes exhaust gas purification system of the engine. The method of claim 12,
Wherein the plurality of oxidation catalysts are formed to have the same cell density and pore size of the carrier. The method according to any one of claims 1 to 13,
The carrier is formed from at least one of a foam made of ceramic or metal, a thin metal laminate, and a metal wire molded body, wherein the noble metal catalyst comprises at least one of platinum, rhodium, and palladium and is combined with the washcoat. The exhaust gas purification system of the engine is coated on its surface. The method of claim 14,
Further comprising a nitrogen oxide reduction device installed in the discharge pipe of the rear end of the turbine,
The nitrogen oxide reduction device,
A catalyst unit of a selective catalyst reduction method; And
Injector for injecting a reducing agent toward the catalyst portion in front of the catalyst portion
Exhaust gas purification system of the engine comprising a. A marine engine comprising the exhaust gas purification system of claim 1. The method of claim 16,
Further comprising a nitrogen oxide reduction device installed in the discharge pipe of the rear end of the turbine,
The nitrogen oxide reduction device,
A catalyst unit of a selective catalyst reduction method; And
Injector for injecting a reducing agent toward the catalyst portion in front of the catalyst portion
Marine engine comprising a.

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