KR20170035683A - Post-processing apparatus for reducing exhaust gas of commercial vehicle - Google Patents

Abstract

The present invention relates to a post-treatment apparatus for reducing exhaust gas of a commercial vehicle. The post-treatment apparatus relates to a diesel oxidation catalyst unit (10) which is arranged on exhaust gas discharge pipes (4) discharged from an engine (1); a diesel particulate filter unit (20) which is arranged on the rear of the diesel oxidation catalyst unit (10) along the exhaust gas discharge pipes (4); a selective catalyst reduction unit (30) spaced apart from the diesel particulate filter unit (20) along the exhaust gas discharge pipes (4); a dosing unit (50) which sprays a reducing agent to the exhaust gas discharge pipes (4) while being arranged between the diesel particulate filter unit (20) and the selective catalyst reduction unit (30); and a mixer (60) arranged between the diesel particulate filter unit (20) and the selective catalyst reduction unit (30). The mixer (60) is arranged on the rear end of the dosing unit (50).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a post-processing apparatus for reducing exhaust gas of a commercial vehicle,

The present invention relates to a post-treatment apparatus for exhaust gas reduction of a commercial vehicle. More particularly, the present invention relates to a manufacturing technology of a post-treatment device for exhaust gas reduction of a commercial vehicle, which effectively removes soot, PM, and NO _x generated in a commercial vehicle through control of the number of urea sprayed on the exhaust gas flow passage .

Recently, the inflow of fine dust generated from domestic and foreign countries has led to an increase in mortality and morbidity rate due to air pollution, and fossil fuels used in the rapid industrialization process have been identified as the main cause of air pollution. In the past, when regulations on pollutant emissions were strengthened, there was a tendency to think that air pollution would not be a major threat to human health. However, even in countries with low levels of air pollution such as the US and Europe recently, Mortality and morbidity rates are reported to be significantly related to the problem.

In Korea, the importance of air pollution has been recognized since the late 1990s, and studies have been conducted on the prevention of such pollution. Especially, since the concentration of fine dust is relatively higher than other countries, the risk due to exposure to fine dust is very high .

Fine dust particles are floating substances in an atmosphere having a very complicated composition, and tend to be generated mainly from automobile exhaust gas and road dust, etc. In general, the diameter of the fine particles is 0.1 to 2.5 μm, ≪ / RTI > less than 0.1 m.

Recently, we have recognized the importance of PM10 (≤10㎛) or PM2.5 (≤2.5㎛) in domestic and foreign countries, and various regulating devices are being prepared. However, it is judged that the potential risk of materials smaller in size is larger, Technology research is underway. Particularly, it has been reported that the micro-dust having a diameter of 100 nm or less has an increased risk of human body due to an increase in surface area as the particle size is smaller. Most of the automobile exhaust gas is composed of a very small number of tenants, Is known as a major cause of.

In order to prevent environmental pollution caused by exhaust gas from automobiles, advanced countries have been striving to regulate pollutants such as PM, CO2 and NO _X from 2005 without applying after-treatment system. It is strengthening.

Currently, the exhaust emission regulations are being phased in, and the emission regulation of diesel vehicles is being regulated to the EURO-V level, as well as the development of the EURO-Ⅵ-compliant exhaust emission purifiers for commercial vehicles. In addition, it is urgent to develop an exhaust gas purification system that can cope with the regulation of exhaust emission of automobiles according to domestic and foreign environmental regulations. However, there is no development of EURO-Ⅵ response exhaust purification system for domestic 3.5 ton trucks.

As a conventional document for suggesting an apparatus for purifying exhaust gas of a diesel vehicle, reference is made to Registration No. 10-1191883 (Oct. 16, 2012). The present invention discloses an exhaust gas purifying apparatus for a diesel vehicle having a fuel injecting device and a fuel injecting device disposed on a post-treatment device composed of a diesel oxidation catalyst coated with a highly active catalyst and a diesel particulate filter, , The exhaust gas purifying device can not meet the exhaust emission regulations of automobiles due to the domestic and foreign environmental regulations, and the fact that it can generate heat source in small and medium-sized vehicles with low exhaust gas temperature and after- There is a limit to concentrate on the room.

(Patent Document 1) KR10-1191883 B

In order to control the large amount of reducing agent required in a diesel engine, the present invention aims at optimizing the urea water spraying and at the same time, it is possible to mix the injected urea water with the exhaust gas to be mixed quickly and uniformly It is an object of the present invention to provide a post-treatment device for exhaust gas reduction of a commercial vehicle, which effectively reduces soot, PM, and NO _x generated in a commercial vehicle so as to satisfy the EURO-VI standard in future.

It is also an object of the present invention to provide a post-treatment apparatus for simultaneously removing PM and NO _x from a combined system including DOC, DPF, SCR, and AOC to ensure excellent durability and price competitiveness.

To achieve the above object, there is provided a post-treatment apparatus for exhaust gas reduction of a commercial vehicle, comprising: a diesel oxidation catalyst unit (10) positioned on an exhaust gas exhaust pipe (4) exhausted from an engine (1); A diesel particulate filter unit (20) disposed behind the diesel oxidation catalyst unit (10) along the exhaust gas exhaust pipe (4); A selective catalytic reduction unit (30) spaced apart from the diesel particulate filter unit (20) along the exhaust gas exhaust pipe (4); A dosing unit (50) for injecting a reducing agent into the exhaust gas exhaust pipe (4) while being disposed between the diesel particulate filter unit (20) and the selective catalytic reduction unit (30); And a mixer 60 disposed between the diesel particulate filter unit 20 and the selective catalytic reduction unit 30. The mixer 60 is installed on the rear end of the dosing unit 50. [

The post-treatment apparatus further includes an ammonia oxidation catalyst unit (40) connected to the rear of the selective catalytic reduction unit (30).

The mixer (60) is attached to the inner circumferential surface of the exhaust gas exhaust pipe (4) in a close contact manner.

The mixer 60 includes a body 61 in which a plurality of concentric circles 62 are arranged at predetermined intervals along a radial direction and a plurality of concentric circles 62 arranged at predetermined intervals along a circumferential direction on a front surface of one side of the body 61 And the plurality of guide blades 65 are arranged to extend in the radial direction from the center of the body 61 toward the edge side and are inclined at a predetermined angle.

The post-treatment apparatus is configured to regulate the collection amount of particulate matter (PM) through the exhaust gas exhaust pipe 4 in a state of being disposed between the diesel particulate filter unit 20 and the selective catalytic reduction unit 30 A first substance sensing unit 91 for sensing the first substance; And a second material sensing unit 93 disposed in front of the selective catalytic reduction unit 30 and behind the ammonia oxidation catalyst unit 40.

As described above, the exhaust gas aftertreatment apparatus for a commercial vehicle according to the present invention optimizes the urea water spray for control of a large amount of reducing agent required in a diesel engine, and at the same time, PM and NO _x generated in commercial vehicles to satisfy the EURO-Ⅵ standard through the design of mixer for uniform mixing.

The present invention aims at securing the ability to develop post-treatment equipment satisfying exhaust emission regulations in the agricultural and construction machinery fields through product development that can satisfy EURO-Ⅵ emission regulations of domestic commercial vehicles, It is expected to secure technological competitiveness with advanced manufacturers and contribute to import substitution by securing its own technology.

The development of the 3.5-ton post-treatment device for EURO-Ⅵ that reduces PM and NO _x emitted from diesel is the first device developed in Korea. It can secure domestic technology competitiveness in the fields led by leading foreign manufacturers, It will be a chance to gain competitiveness in the field of bus post-processing device development.

The DOC, DPF and SCR combined exhaust system, which is the core technology of the present invention, is an opportunity to secure post-processing exhaust system technology corresponding to EURO-Ⅵ in Korea, and it can secure cost competitiveness equivalent to that of advanced foreign manufacturers.

In the present invention, since the emission amount of fine particles of several tens of nanometers or less is increasing due to the increase of the injection pressure of the diesel engine, the environmental damage of the micro leaner is continuously reported, and the quantitative capture and particle collection performance It is expected that it will be possible to reduce environmental pollutants as an exhaust system capable of simultaneously reducing PM and nitrogen oxide.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an overall schematic diagram of a post-treatment apparatus for gases exhausted from an engine in accordance with the present invention;
2 is a conceptual diagram of a post-treatment device for exhaust gas reduction according to an embodiment of the present invention.
3 is a perspective view of the mixer 60. Fig.
4 is a simplified model of a post-treatment apparatus for thermal flow analysis.
5 is a table showing the analysis conditions for the internal heat flow analysis.
FIG. 6 shows the results of the analysis for the internal heat flow analysis.
Fig. 7 is a view showing the arrangement of the dosing unit 50. Fig.
8 is a view showing the arrangement between the dosing unit 50 and the selective catalytic reduction unit 30. FIG.
9 is a view showing the shape of the exhaust pipe 4 in which the mixer 60 is disposed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of other various forms of implementation, and that these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know completely. Wherein like reference numerals refer to like elements throughout.

It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

Hereinafter, a post-treatment apparatus for exhaust gas reduction of a commercial vehicle according to the present invention will be described with reference to Figs. 1 and 2. Fig.

The post-treatment apparatus for exhaust gas reduction includes a hydrocarbon supply unit 70 sequentially disposed on an exhaust gas exhaust pipe 4 exhausted from an engine 1 equipped with an exhaust gas recirculator (EGR) 2, A diesel particulate filter unit 20 disposed at the rear of the diesel oxidation catalyst unit 10, an exhaust gas exhaust pipe 4, a diesel particulate filter unit 20 disposed behind the diesel oxidation catalyst unit 10, A Selective Catalytic Reduction Unit 30 disposed to be spaced apart from the diesel particulate filter unit 20 along the exhaust passage 30 and an ammonia oxidation catalyst unit 40 connected to the rear of the selective catalytic reduction unit 30, A dosing unit 50 for injecting a reducing agent into the exhaust gas exhaust pipe 4 while being disposed between the diesel particulate filter unit 20 and the selective catalytic reduction unit 30, a diesel particulate filter unit 20, Between the reduction unit (30) A plurality of temperature sensing sensors 81, 82, 83, 84 disposed on the exhaust gas exhaust pipe 4, a diesel particulate filter unit 20 and a selective catalytic reduction unit 30 A first material sensing part 91 for sensing the amount of particulate matter (PM) captured through the exhaust gas exhaust pipe 4 in a deployed state, a first material sensing part 91 for sensing the amount of particulate matter (PM) captured before the selective catalytic reduction unit 30 and the ammonia oxidation catalyst unit And a second material sensing part (93) disposed behind the first material sensing part (40).

The diesel oxidation catalyst unit 10 has a reaction promoting function for supporting HC and CO of the exhaust gas to chemically change or oxidize into H ₂ O and CO _2. The shape of the catalyst is a pellet- Type, and the material of the carrier can be coated with rhodium or palladium on the surface of the alumina ceramic. Soluble organic fractions (SOF) composed of lube oil and particulate phase of diesel engine occupy a high proportion of the constituents of PM, and they are removed considerably through diesel oxidation catalyst unit (10) do.

Since the diesel oxidation catalyst unit 10 plays an important role in reducing the total mass of PM and the efficiency of the selective catalytic reduction unit 30 is very important for coping with the NO _x regulation, the ratio of NO and NO ₂ can be appropriately adjusted It maintains high NO _x purification efficiency of SCR even in exhaust temperature environment.

The diesel particulate filter unit 20 performs the PM trapping and regenerating technique and basically includes three parts: a filter, a regenerating device, and a control device. The material or shape of the filter is an important factor that determines the performance of the diesel particulate filter system. Monolith type is the most common type, and cartridge type, knit type, etc. can also be employed. The filter material may adopt any one of the group consisting of cotdierite, silicon carbide (SiC), fiber, metal powder and the like.

The regeneration system of the diesel particulate filter unit 20 employs a forced regeneration regime and a natural regeneration regime. The forced regeneration method is a method of forcibly heating the captured PM to the soot ignition temperature of 500 to 600 ° C from the outside, using an electric heater or butter. The natural regeneration method is a method of regenerating the engine exhaust gas temperature by lowering the soot ignition temperature to about 250 ° C. by using a catalyst or an additive agent. The catalytic coating of the filter trap, the additive to the fuel, and the fuel are injected in front of the trap .

In the selective catalytic reduction unit 30, an urea aqueous solution (NH ₂ CO) or ammonia (NH ₃ ) is injected onto the NO _X gas contained in a large amount in the exhaust gas of the vehicle, thereby reducing NO _x to nitrogen and water vapor. Some of the catalytic structure of the selective catalytic reduction unit 30 may be a structure protruding onto a pellet or a uniform monolith, and the other part may be a structure supported in a honeycomb structure made of a parallel metal plate or ceramic.

Two types of ammonia are used, which include pure anhydrous or water-containing ammonia. Anhydrous ammonia is toxic and dangerous and requires high pressure vessels and pipes because of its high vapor pressure. Functional ammonia is relatively less dangerous and easier to handle. In general, industrial ammonia is composed of 27% ammonia and 73% water by weight, and it is easy to transport because it has almost atmospheric pressure vapor pressure at normal temperature.

For the reaction process in the selective catalytic reduction unit 30, it is necessary to control the precise amount of ammonia injection rate. If the ammonia is not sprayed sufficiently, the conversion efficiency of NO _X becomes low. If too much is injected, The function of the dosing unit 50 becomes important.

Urea can be used as a reducing agent instead of ammonia. Compared with ammonia, urea is relatively non-toxic, safe and easy to handle and is widely used for SCR catalysts in automobiles. The solubility of urea is at least 50%, but the concentration of the aqueous urea solution used in the SCR system may generally be 32.5% wt. At this concentration, the urea becomes a eutectic liquid having a crystal point of -11 캜, and by using such a urea eutectic liquid, it is possible to utilize the advantage that the concentration of liquid and solid phase is the same during crystallization. That is, even if the crystallization progresses due to partial condensation in the urea tank, the concentration of the urea aqueous solution supplied to the SCR system does not change.

The hydrocarbon supply unit 70, the diesel oxidation catalyst unit 10, the diesel particulate filter unit 20, and the like are formed in a tube-shaped housing having flanges such as flanges on both sides of the exhaust gas exhaust pipe 4 . The diesel oxidation catalyst unit 10 and the diesel particulate filter unit 20 can be manufactured as one integrated module to reduce the overall size.

Likewise, the selective catalytic reduction unit 30 and the ammonia oxidation catalytic unit 40 can also be fabricated as a single integrated module to reduce the overall size.

The present invention is to provide a 3.5-ton commercial EURO-Ⅵ-compliant aftertreatment system, which uses an appropriate level of exhaust gas recirculation (EGR) and enhances DPF performance to find ways to cope with increased PM in the combustion chamber. In this case, high technological barriers to high-efficiency SCR can be solved, and the technical elements applied to EURO-V and the like can be actively utilized.

On the other hand, the most important factor in EURO-VI SCR technology is to secure high NO _x purifying efficiency. Especially, in heavy-duty diesel, the amount of reducing agent is large, So that the mixing unit 60 for quickly and uniformly mixing the injected urea water with the exhaust gas is installed to prevent the problem.

The dosing unit 50 functions to inject a reducing agent into the exhaust gas exhaust pipe 4 and injects urea water onto the exhaust gas discharged via the diesel particulate filter unit 20. [ A mixer (60) is installed on the rear end of the dosing unit (50) in order to enable uniform mixing of the urea water and the exhaust gas in the above injection process.

The mixer (60) is attached to the inner circumferential surface of the exhaust gas exhaust pipe (4) in a close contact manner. For example, the mixer 60 installed in the hollow cylindrical exhaust gas exhaust pipe 4 is installed so that its outside diameter matches the inside diameter of the exhaust gas exhaust pipe 4.

3, the mixer 60 includes a body 61 in which a plurality of concentric circles 62 having different diameters and a constant width are disposed at predetermined intervals along the radial direction, And a plurality of guide blades 65 disposed on the front portion at predetermined intervals along the circumferential direction.

It is preferable that the plurality of guide blades 65 extend radially from the center of the body 61 to the edge side, and are arranged to be inclined at a predetermined angle as a whole.

Referring to FIG. 7, the dosing unit 50 is optimized to spray the urea spray liquid evenly on the front surface of the mixer 60 in order to improve the exhaust gas purifying performance. To this end, the dosing unit (50) is disposed in an inclined state on the protrusion formed on the exhaust gas exhaust pipe (4).

8, by setting the optimum distance from the dosing unit 50 to the front end of the selective catalytic reduction unit 30, the purification performance of the exhaust gas can be maximized.

9, it is possible to add the heat insulating material 5 in the form of surrounding the exhaust gas exhaust pipe 4 in which the dosing unit 50 is disposed. The heat insulating material 5 performs insulation for the mixing chamber which is a space from the dosing unit 50 to the mixer 60 in the space inside the exhaust gas exhaust pipe 4. This makes it possible to prevent the crystallization of urea and to maintain the exhaust gas temperature for improving the exhaust gas purification performance of the catalyst.

Hereinafter, the internal heat flow analysis for the exhaust gas reducing post-treatment apparatus of a commercial vehicle according to the present invention will be described.

This internal heat flow analysis is intended to evaluate the flow characteristics of the mixer (60) improvement and SCR front-end pier installation for the NH ₃ purification rate of 3.5-ton commercial EURO-Ⅵ compliant post-treatment equipment through optimization of internal structure.

FIG. 4 shows the model simplification process for the heat flow analysis, and FIG. 5 shows the analysis conditions and results for the internal heat flow analysis.

Referring to FIG. 6, it can be confirmed that the diesel oxidation catalyst unit 10, the diesel particulate filter unit 20, and the selective catalytic reduction unit 30 all satisfy the flow velocity uniformity.

As described above, the post-treatment device for exhaust gas reduction of a commercial vehicle according to the present invention optimizes the urea water spray for control of a large amount of reducing agent required in a diesel engine, and at the same time, PM and NO _x generated in commercial vehicles to satisfy the EURO-Ⅵ standard through the design of mixer for uniform mixing.

It is to be understood that the terms "comprises", "comprising", or "having" as used in the foregoing description mean that the constituent element can be implanted unless specifically stated to the contrary, But should be construed as further including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (5)

A diesel oxidation catalyst unit (10) located on an exhaust gas exhaust pipe (4) exhausted from the engine (1);
A diesel particulate filter unit (20) disposed behind the diesel oxidation catalyst unit (10) along the exhaust gas exhaust pipe (4);
A selective catalytic reduction unit (30) spaced apart from the diesel particulate filter unit (20) along the exhaust gas exhaust pipe (4);
A dosing unit (50) for injecting a reducing agent into the exhaust gas exhaust pipe (4) while being disposed between the diesel particulate filter unit (20) and the selective catalytic reduction unit (30); And
And a mixer (60) disposed between the diesel particulate filter unit (20) and the selective catalytic reduction unit (30)
The mixer (60) is provided on the rear end of the dosing unit (50)
A post-treatment device for exhaust gas reduction.
The method according to claim 1,
The post-
And an ammonia oxidation catalyst unit (40) connected and arranged behind the selective catalytic reduction unit (30).
A post-treatment device for exhaust gas reduction.
3. The method of claim 2,
The mixer (60) is attached to the inner circumferential surface of the exhaust gas exhaust pipe (4)
A post-treatment device for exhaust gas reduction.
3. The method of claim 2,
The mixer (60)
A plurality of concentric circles 62 arranged in the radial direction at predetermined intervals and a plurality of guide blades 65 arranged at predetermined intervals along the circumferential direction on one side of the front surface of the body 61 ),
The plurality of guide blades (65) extend radially from the center of the body (61) to the edge side, and are arranged in a tilted state at a predetermined angle.
A post-treatment device for exhaust gas reduction.
The method according to claim 1,
The post-
A first substance detection unit for detecting a trapped amount of particulate matter (PM) through the exhaust gas exhaust pipe (4) in a state of being disposed between the diesel particulate filter unit (20) and the selective catalytic reduction unit (30) A portion 91; And
Further comprising: a second material sensing unit (93) disposed in front of the selective catalytic reduction unit (30) and behind the ammonia oxidation catalyst unit (40)
A post-treatment device for exhaust gas reduction.

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