DE102016003743A1 - Exhaust after treatment system and internal combustion engine - Google Patents

Abstract

Exhaust gas aftertreatment system, namely SCR exhaust aftertreatment system, an internal combustion engine, with an SCR catalyst (9) accommodated in a reactor chamber (10), with an exhaust gas feed line (8) leading to the reactor chamber (10) and thus to the SCR catalytic converter (9) from the reactor chamber (10) and thus from the SCR catalytic converter (9) leading away exhaust gas discharge (11), with one of the exhaust gas supply line (8) associated introduction device (16) for introducing a reducing agent, in particular ammonia or an ammonia precursor substance in the exhaust gas, and with a mixing section (18) provided by the exhaust gas feed line (8) downstream of the introduction device (16) for mixing the exhaust gas with the reducing agent upstream of the reactor space (10) or SCR catalyst (9), wherein within the reactor space (10) at least a blowing device (24) is positioned, which serves to blow the SCR catalyst (9).

Description

The invention relates to an exhaust aftertreatment system of an internal combustion engine. Furthermore, the invention relates to an internal combustion engine with an exhaust aftertreatment system.

In combustion processes in stationary internal combustion engines, which are used for example in power plants, as well as combustion processes in non-stationary internal combustion engines, which are used for example on ships, resulting in nitrogen oxides, these nitrogen oxides typically in the combustion of sulfur-containing fossil fuels, such as coal, hard coal , Brown coal, petroleum, heavy fuel oil or diesel fuels. Therefore, such internal combustion engines are assigned exhaust aftertreatment systems that serve the cleaning, in particular the denitrification, of the exhaust gas leaving the internal combustion engine.

To reduce nitrogen oxides in the exhaust gas, so-called SCR catalysts are used in practice in exhaust gas aftertreatment systems known from practice. In a SCR catalyst, a selective catalytic reduction of nitrogen oxides takes place, whereby ammonia (NH ₃ ) is required as reducing agent for the reduction of the nitrogen oxides. The ammonia or an ammonia precursor substance, such as urea, for this purpose, is introduced into the exhaust gas upstream of the SCR catalyst in liquid form, with the ammonia or the ammonia precursor substance being mixed with the exhaust gas upstream of the SCR catalytic converter. For this purpose, mixing paths between the introduction of the ammonia or of the ammonia precursor substance and the SCR catalyst are provided according to the practice.

Although exhaust gas aftertreatment, in particular nitrogen oxide reduction, can already be successfully carried out using exhaust gas aftertreatment systems which comprise an SCR catalytic converter known from practice, there is a need to further improve the exhaust aftertreatment systems. In particular, there is a need to allow for a compact design of such exhaust aftertreatment systems effective exhaust aftertreatment.

On this basis, the present invention has the object to provide a novel exhaust aftertreatment system of an internal combustion engine and an internal combustion engine with such an exhaust aftertreatment system.

This object is achieved by an exhaust aftertreatment system of an internal combustion engine according to claim 1. According to the invention at least one blowing device is positioned within the reactor space, which serves for blowing out the SCR catalyst. Blocking of the SCR catalyst as a result of the same depositing soot particles can thus be avoided. With a compact design of the exhaust aftertreatment system, effective exhaust gas purification can be ensured.

According to an advantageous development of the present invention, the or each blowing device is aligned such that it causes a swirling or swirling flow on a transverse to the flow direction surface of the SCR catalyst, in particular on a transversely, preferably perpendicular, extending to the flow direction, upstream surface of honeycomb bodies of the SCR catalyst. Blocking the SCR catalyst as a result of depositing itself on the same soot particles can be so effectively avoided. With a compact design of the exhaust aftertreatment system, effective exhaust gas purification can be ensured.

According to an advantageous development of the present invention, the reactor space has a round wall in cross-section, in particular a circular wall. This is preferred for the formation of the vortex flow or swirl flow. This allows a compact design a particularly effective exhaust aftertreatment.

According to a further advantageous development of the present invention, each blowing device is positioned adjacent to the cross-sectionally round wall of the reactor space and blows from the wall inwardly into the reactor space, with a blowing cone which intersects the blowing cone of at least one other blowing device. This is preferred for the formation of the vortex flow or swirl flow as well as for the full-surface blowing off of the soot particles. This allows a compact design a particularly effective exhaust aftertreatment.

According to a further advantageous development of the present invention, the exhaust gas feed line has a downstream end into the reactor space, wherein within the reactor space between the downstream end of the exhaust gas feed line and the SCR catalyst, a device for increasing an exhaust gas back pressure upstream of the SCR catalyst is positioned. By means of the device for increasing the exhaust back pressure upstream of the SCR catalyst, the exhaust gas flow upstream of the SCR catalyst is stagnated, whereby it can be achieved that the SCR catalyst is uniformly supplied with the exhaust gas flow, both in the circumferential direction and in the radial direction. This can be in a compact design of the Exhaust aftertreatment system to ensure even more effective emission control. Furthermore, soot particles can deposit on the device for increasing the exhaust backpressure, which then can no longer get into the region of the SCR catalytic converter and block it. This also serves to ensure effective exhaust gas purification in a compact design of the exhaust aftertreatment system.

Preferably, the or each blowing device is positioned within the reactor space between the exhaust backpressure increasing device and the SCR catalyst. In this case, the or each blowing device then serves at least the blowing out of the SCR catalytic converter, and preferably additionally the blowing out of the device for increasing an exhaust backpressure. This development allows a compact design a particularly effective exhaust aftertreatment.

The internal combustion engine according to the invention is defined in claim 11.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. Embodiments of the invention will be described, without being limited thereto, with reference to the drawings. Showing:

1 a schematic, perspective view of an internal combustion engine with an exhaust aftertreatment system according to the invention;

2 : a detail of the exhaust aftertreatment system of 1 ;

3 : a detail of 2 ;

4 a cross section through the detail of 3 ,

The present invention relates to an exhaust aftertreatment system of an internal combustion engine, such as a stationary internal combustion engine in a power plant or on a ship used, non-stationary internal combustion engine. In particular, the exhaust aftertreatment system is used on a heavy fuel oil marine diesel engine.

1 shows an arrangement of an internal combustion engine 1 with an exhaust gas turbocharging system 2 and an exhaust aftertreatment system 3 , In the internal combustion engine 1 it may be a transient or stationary internal combustion engine, in particular a marine engine. Exhaust gas, which is the cylinder of the internal combustion engine 1 leaves is in the exhaust charging system 2 used to extract from the thermal energy of the exhaust gas mechanical energy for compression of the internal combustion engine 1 to gain supplied charge air. So shows 1 an internal combustion engine 1 with an exhaust gas turbocharging system 2 , which comprises a plurality of exhaust gas turbochargers, namely a first, high pressure side exhaust gas turbocharger 4 and a second, low pressure side exhaust gas turbocharger 5 , Exhaust gas, which is the cylinder of the internal combustion engine 1 leaves, first flows through a high-pressure turbine 6 of the first exhaust gas turbocharger 1 and is relaxed in the same, wherein this energy recovered in a high-pressure compressor of the first exhaust gas turbocharger 4 is used to compress charge air. In the flow direction of the exhaust gas is seen downstream of the first exhaust gas turbocharger 4 the second turbocharger 5 arranged over which exhaust gas, which is already the high-pressure turbine 6 of the first exhaust gas turbocharger 4 has passed through, namely, a low-pressure turbine 7 the second exhaust gas turbocharger 5 , In the low-pressure turbine 7 the second exhaust gas turbocharger 5 the exhaust gas is further expanded and thereby recovered energy in a low-pressure compressor of the second exhaust gas turbocharger 5 used also to the cylinders of the internal combustion engine 1 to compress supplied charge air.

In addition to the two exhaust gas turbochargers 4 and 5 having exhaust gas charging system 2 includes the internal combustion engine 1 the exhaust aftertreatment system 3 , which is an SCR exhaust aftertreatment system. The SCR exhaust aftertreatment system 3 is between the high pressure turbine 6 and the low-pressure turbine 7 switched, so therefore exhaust, which is the high-pressure turbine 6 of the first exhaust gas turbocharger 4 leaves, first via the SCR exhaust aftertreatment system 3 can be performed before the same in the field of low-pressure turbine 7 the second exhaust gas turbocharger 5 arrives.

1 shows an exhaust gas supply line 8th , about the exhaust, starting from the high-pressure turbine 6 of the first exhaust gas turbocharger 4 towards an SCR catalyst 9 can be performed in a reactor room 10 is arranged. Further shows 1 an exhaust gas discharge 11 , the discharge of the exhaust gas from the SCR catalyst 9 or from the reactor space 10 towards the low-pressure turbine 7 the second exhaust gas turbocharger 5 serves. Starting from the low-pressure turbine 7 the exhaust gas flows through a pipe 21 especially outdoors. The to the reactor room 10 and thus to the reactor room 10 positioned SCR catalyst 9 leading exhaust gas supply 8th as well as from the reactor room 10 and thus from the SCR catalyst 9 leading exhaust gas discharge 11 are over a bypass 12 coupled, in which a shut-off 13 is integrated. When the shut-off device is closed 13 is the bypass 12 locked, so that no exhaust gas can flow over it. Then, however, when the obturator 13 opened, can over the bypass 12 Exhaust gas flow, past the reactor room 10 and therefore past the SCR catalyst 9 , 2 illustrated with arrows 14 the flow of exhaust gas through the exhaust aftertreatment system 3 at over the obturator 13 closed bypass 12 , in which 2 it can be seen that the exhaust gas supply line 8th in the reactor room 10 with a downstream end 15 opens, with the exhaust gas in the region of this end 15 the exhaust gas supply line 8th a flow deflection by approximately or approximately 180 ° learns, and wherein the exhaust subsequently via the SCR catalyst 9 to be led.

The exhaust gas supply line 8th the exhaust aftertreatment system 3 is a loading device 16 assigned, can be introduced via the in the exhaust stream, a reducing agent, in particular ammonia or an ammonia precursor substance, which is needed to in the range of the SCR catalyst 9 Defined to implement nitrogen oxides of the exhaust gas. In this introduction device 16 the exhaust aftertreatment system 3 it is preferably an injection nozzle, via which the ammonia or the ammonia precursor substance into the exhaust gas stream within the Abgaszuführleitung 8th is injected. 2 illustrated with a cone 17 the injection of the reducing agent into the exhaust gas flow in the region of the exhaust gas supply line 8th ,

The route of the exhaust aftertreatment system 3 , seen in the flow direction of the exhaust gas downstream of the introduction device 16 and upstream of the SCR catalyst 9 is, is referred to as a mixing section. In particular, the exhaust gas supply line 8th downstream of the introduction device 16 a mixed route 18 in which the exhaust gas with the reducing agent upstream of the SCR catalyst 9 can be mixed.

The exhaust gas supply line 8th flows with the downstream end 15 in the reactor room 10 , This downstream end 15 the exhaust gas supply line 8th is a baffle element 20 assigned, which is relative to the downstream end 15 the exhaust gas supply line 8th is relocatable. In the embodiment shown, the baffle element 20 relative to the end 15 the exhaust gas supply line 8th which is in the reactor room 10 flows, linearly displaceable. The impact element 20 is relative to the downstream end 15 the exhaust gas supply line 8th relocatable to either the exhaust gas supply 8th at the downstream end 15 shut off or the same at the downstream end 15 release. Then, if the baffle element 20 the exhaust gas supply line 8th at the downstream end 15 shut off, is preferably the obturator 13 of the bypass 12 then open the exhaust completely on the SCR catalyst 9 or on which the SCR catalyst 9 receiving reactor space 10 passing out. Then, if the baffle element 20 the downstream end 15 the exhaust gas supply line 8th releases, the obturator can 13 of the bypass 12 either completely closed or at least partially open.

Then, if the baffle element 20 the downstream end 15 the exhaust gas supply line 8th releases, is the relative position of the impact element 20 relative to the downstream end 15 the exhaust gas supply line 8th in particular of the exhaust gas mass flow through the exhaust gas supply line 8th and / or the exhaust gas temperature of the exhaust gas in the exhaust gas supply line 8th and / or the amount of the via the introduction device 16 in the exhaust gas flow introduced reducing agent dependent.

Another function of the impact element 20 with released, downstream end 15 the exhaust gas supply line 8th is that possibly present in the exhaust stream drops of liquid reducing agent on the impact element 20 get trapped and atomized there to avoid such drops of liquid reducing agent in the area of the SCR catalyst 9 reach. About the relative position of the impact element 20 to the downstream end 15 the exhaust gas supply line 8th with the downstream end enabled 15 In particular, it can be determined whether the exhaust gas which is in the region of the downstream end 15 the exhaust gas supply line 8th in the area of the impact element 20 is deflected, more toward radially inwardly positioned sections or more towards radially outwardly positioned sections of the SCR catalyst 9 is directed or directed.

According to a preferred embodiment, the exhaust gas supply line 8th in the region of its downstream end 15 widened funnel-shaped formation of a diffuser. As a result, the flow cross section of the exhaust gas supply line increases 8th in the area of the downstream end 15 , where, in particular 2 can be taken, it can be provided that seen in the flow direction of the exhaust gas upstream of the downstream end 15 the exhaust gas supply line 8th the flow cross section of the same initially reduced. So shows 2 in that the flow cross section of the exhaust gas supply line 8th seen in the flow direction of the exhaust gas downstream of the introduction device 16 is initially approximately constant for the reducing agent, then initially gradually tapers and finally in the region of the downstream end 15 extended.

This extension of the flow cross-section at the downstream end 15 the exhaust gas supply line 8th takes place vorzugwseise over a shorter section of the exhaust gas supply line 8th as the one Section over which the exhaust gas supply line 8th in front of the downstream end 15 initially rejuvenated.

The impact element 20 is preferably at one of the exhaust gas supply line 8th facing side 22 arched to form a flow guide for the exhaust, preferably curved like a bell. This is how the side of the impact element points 20 that is the downstream end 15 the exhaust gas supply line 8th facing, at a radially inner portion of the impact member 20 a smaller distance to the downstream end 15 the exhaust gas supply line 8th on than at a radially outer portion thereof. The impact element 20 is therefore in the center towards the downstream end 15 the exhaust gas supply line 8th retracted or curved against the flow direction of the exhaust gas.

As already stated, the exhaust gas feed line opens 8th with its downstream end 15 in the reactor room 10 which is the SCR catalyst 9 receives. At the same time permeates according to 2 the exhaust gas supply line 8th a lower side of the reactor space 10 and ends with its downstream end 15 adjacent to an upper side 23 of the reactor space 10 wherein, as already stated, the exhaust gas, which is the exhaust gas feed line at the downstream end 15 leaves, is deflected by 180 °, before the same subsequently via the SCR catalyst 9 flows.

In particular 3 can be taken is between the downstream end 15 the exhaust gas supply line 8th and the SCR catalyst 9 a device 25 to increase exhaust back pressure upstream of the SCR catalyst 9 positioned. In this device 25 to increase the exhaust backpressure may be, for example, a grid, a perforated plate or the like.

With the help of the device 25 to increase the exhaust back pressure upstream of the SCR catalyst 9 the exhaust gas flow becomes upstream of the SCR catalyst 9 accumulated, which can be achieved that the SCR catalyst 9 is applied uniformly with the exhaust gas flow, in the circumferential direction as well as in the radial direction.

The device 25 To increase the exhaust backpressure has the advantage that can be deposited on the same soot particles contained in the exhaust gas. Those soot particles that are on the device 25 To deposit the exhaust back pressure, can no longer in the range of the SCR catalyst 9 arrive and the same, namely honeycomb body 27 same, do not clog. 3 and 4 show several round cross-section honeycomb body 27 of the SCR catalyst 9 ,

The device 25 to increase the exhaust gas back pressure has a free flow cross section, the maximum of 2 times, preferably at most 1 times, more preferably at most 0.5 times, the free flow cross section of the SCR catalyst 9 or the honeycomb body 27 of the SCR catalyst 9 equivalent. This can on the one hand equalize the flow of exhaust gas through the SCR catalyst 9 On the other hand, it can be ensured that soot particles are already in the area of the device 25 to increase the exhaust back pressure and no longer in the range of the SCR catalyst 9 reach.

Preferably, a ratio between the thickness or length of the device seen in the flow direction or exhaust gas flow direction is 25 for increasing the exhaust back pressure and the thickness or length of the SCR catalyst seen in the flow direction or exhaust gas flow direction 9 or the honeycomb body 27 of the SCR catalyst 9 at least 1:50, preferably at least 1: 100, more preferably at least 1: 200.

Preferably, a ratio between the distance, the distance between the device 25 to increase the exhaust backpressure and the SCR catalyst 9 in the flow direction or in the exhaust gas flow direction, and the thickness or length of the SCR catalyst seen in the direction of flow 9 9 or the honeycomb body 27 of the SCR catalyst 9 a maximum of 2: 1, preferably a maximum of 1: 1, more preferably a maximum of 1: 2.

About in the reactor room 10 positioned device 25 to increase the exhaust gas back pressure can uniform loading of the SCR catalyst 9 be ensured with exhaust gas. By increasing the exhaust back pressure, the exhaust gas flow is dammed up and thereby a uniform distribution of the exhaust gas through the SCR catalyst 9 guaranteed. Another advantage of the device 25 to increase the exhaust back pressure is that it also performs the function of a pre-separator on which soot particles contained in the exhaust gas can deposit. As a result, it is possible to prevent the soot particles from hitting the SCR catalytic converter unhindered 9 get into it and clog it up.

Inside the reactor room 10 is at least one blowing device 24 positioned the free blowing of the SCR catalyst 9 serves. In the illustrated preferred embodiment, the or each blowing device 24 within the reactor space 10 in which the SCR catalyst 9 and continue the device 25 are positioned to increase the exhaust back pressure, wherein the or each blowing device 24 seen in the flow direction of the exhaust gas between the device 25 to increase the exhaust backpressure and the SCR catalyst 9 is arranged. At the or each blowing device 24 it is preferably an air nozzle. The or each blowing device 24 at least serves to blow the SCR catalyst 9 in view of the soot particles depositing thereon, and preferably also the free blowing of the device 25 to increase the exhaust back pressure to block the SCR catalyst 9 and preferably also the device 25 to avoid increasing the exhaust backpressure. The or each blowing device 24 is preferably oriented such that it has a swirling or swirling flow on a transverse to the flow direction surface of the SCR catalyst 9 causes, namely at a direction perpendicular to the flow direction, upstream surface of honeycomb bodies 27 of the SCR catalyst 9 ,

4 shows the preferred orientation of the or each blowing device 24 , which is preferably oriented such that the turbulent flow or swirl flow within the reactor space 10 is generated, in the direction perpendicular to the flow or exhaust gas flow direction, upstream surface of the SCR catalyst 9 and preferably also in a corresponding, perpendicular to the flow or exhaust gas flow direction, downstream surface of the device 25 for increasing the exhaust back pressure, these surfaces each of the or each blowing device 24 are facing. By a vortex flow or swirl flow, the blow-off of soot particles from the SCR catalyst 9 namely the honeycomb bodies 27 the same, and preferably also from the device 25 To increase the exhaust back pressure particularly effective.

The reactor room 10 in which the SCR catalyst 9 and preferably also the device 25 are added to increase the exhaust back pressure, preferably has a round in cross-section, in particular circular, wall 19 on that is between the lower side 22 and the upper side 23 of the reactor space 10 extends. At least that's the wall 19 on an inside, the one at least the SCR catalyst 9 receiving interior of the reactor room 10 defined, round or circular in cross-section. Through such a wall 19 in combination with the orientation of the or each blowing device 24 may be the vortex flow or swirl flow within the reactor space 10 , which is the blowing out of the SCR catalyst 9 and preferably also the blowing out of the device 25 to increase the exhaust back pressure with respect to the same depositing soot particles, are formed particularly advantageous.

Preferably, a plurality of blowing devices 24 in the reactor room 10 positioned, preferably at least three, more preferably at least four, blowing devices 24 ,

The blowing devices 24 are adjacent to the circular cross-section wall 19 of the reactor space 10 positioned and blow starting from this wall 19 Air or compressed air inwards into the reactor chamber 10 into it, with a bubble cone 26 who has the bubble cone 26 at least one other blowing device 24 cuts and thus partially overlaps. This allows a full-surface blowing of the SCR catalyst 9 and preferably also the device 25 be realized or ensured to increase the exhaust back pressure on the above-mentioned surfaces.

The invention allows for a compact design effective exhaust aftertreatment.

In the internal combustion engine 1 of the 1 is the exhaust aftertreatment system 3 standing above the exhaust gas charging system 2 positioned. Access to cylinders of the internal combustion engine 1 is free, the accessibility of the turbocharger 4 and 5 is limited. The reactor room 10 However, if necessary maintenance on the turbochargers 4 . 6 simply be dismantled.

Unlike the in 1 shown standing arrangement of the exhaust aftertreatment system 3 above the exhaust charging system 2 is also a horizontal, tilted by 90 ° arrangement of the exhaust aftertreatment system 3 next to the exhaust charging system 2 possible, but with such a lying arrangement, the length of the arrangement grows. Internal combustion engine 1 and exhaust charging system 2 However, then stand for maintenance without the need to disassemble the reactor space 10 unrestricted available.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

Turbocharging System

3

aftertreatment system

4

turbocharger

5

turbocharger

6

High-pressure turbine

7

Low-pressure turbine

8th

exhaust lead

9

SCR catalyst

10

reactor chamber

11

Flue gas discharge

12

bypass

13

shutoff

14

exhaust system

15

The End

16

introducing device

17

Injection cone

18

mixing section

19

wall

20

Prallelemnet

21

management

22

page

23

page

24

blower

25

contraption

26

Blaskegel

27

honeycombs

Claims (12)

Exhaust aftertreatment system ( 3 ) an internal combustion engine, namely SCR exhaust aftertreatment system of an internal combustion engine, with a in a reactor space ( 10 ) recorded SCR catalyst ( 9 ), with one to the reactor space ( 10 ) and thus to the SCR catalyst ( 9 ) leading exhaust gas supply ( 8th ) and with one from the reactor space ( 10 ) and thus of the SCR catalyst ( 9 ) leading off exhaust gas discharge ( 11 ), with one of the exhaust gas supply line ( 8th ) associated delivery device ( 16 ) for introducing a reducing agent, in particular ammonia or an ammonia precursor substance, into the exhaust gas, and with one of the exhaust gas supply line ( 8th ) downstream of the introduction device ( 16 ) provided mixing section ( 18 ) for mixing the exhaust gas with the reducing agent upstream of the reactor space ( 10 ) or SCR catalyst ( 9 ), characterized in that within the reactor space ( 10 ) at least one blowing device ( 24 ), which is the blowing of the SCR catalyst ( 9 ) serves. Exhaust gas after-treatment system according to claim 1, characterized in that the or each blowing device ( 24 ) is aligned such that it has a swirling flow or swirling flow on a surface of the SCR catalytic converter running transversely, in particular perpendicular, to the throughflow direction ( 9 ) causes. Exhaust gas after-treatment system according to claim 2, characterized in that the or each blowing device ( 24 ) is oriented such that it the vortex flow or swirl flow on a transverse, in particular perpendicular, to the flow direction extending, upstream surface of honeycomb bodies ( 27 ) of the SCR catalyst ( 9 ) causes. Exhaust gas after-treatment system according to one of claims 1 to 3, characterized in that the reactor space ( 10 ) in cross-section a round wall ( 19 ), in particular a circular wall. Exhaust gas after-treatment system according to claim 4, characterized in that each blowing device ( 24 ) adjacent to the cross-sectionally round wall ( 19 ) of the reactor space ( 10 ) is positioned and starting from the wall ( 19 ) inwards into the reactor space ( 10 ), with a blowing cone ( 26 ), the blowing cone ( 26 ) at least one other blowing device ( 24 ) cuts. Exhaust after-treatment system according to one of claims 1 to 5, characterized in that the exhaust gas feed line ( 8th ) with a downstream end ( 15 ) into the reactor space ( 10 ) and that within the reactor space ( 10 ) between the downstream end ( 15 ) of the exhaust gas supply line ( 8th ) and the SCR catalyst ( 9 ) a device ( 25 ) for increasing an exhaust gas back pressure upstream of the SCR catalyst ( 9 ) is positioned. Exhaust gas after-treatment system according to claim 6, characterized in that the or each blowing device ( 24 ) within the reactor space ( 10 ) between the device ( 25 ) to increase an exhaust back pressure and the SCR catalyst ( 9 ) is positioned. Exhaust gas after-treatment system according to claim 6 or 7, characterized in that the device ( 25 ) has a free flow cross-section to increase the exhaust backpressure which is at most 2 times, preferably at most 1 times, particularly preferably 0.5 times, a free flow cross section of the SCR catalyst ( 9 ) corresponds. Exhaust gas aftertreatment system according to one of claims 6 to 8, characterized in that a ratio between the viewed in the direction of flow thickness or length of the device ( 25 ) for increasing the exhaust gas backpressure and the thickness or length of the SCR catalyst seen in the direction of flow ( 9 ) is at least 1:50, preferably at least 1: 100, more preferably at least 1: 200. Exhaust gas after-treatment system according to one of claims 6 to 9, characterized in that a ratio between a distance, the distance between the device ( 25 ) to increase the exhaust back pressure and the SCR catalyst ( 9 ) in the flow direction, and the thickness or length of the SCR catalyst seen in the direction of flow ( 9 ) is at most 2: 1, preferably at most 1: 1, particularly preferably at most 1: 2. Internal combustion engine ( 1 ), in particular with a diesel fuel or with a heavy fuel oil fueled internal combustion engine, with a Exhaust aftertreatment system ( 3 ) according to one of claims 1 to 10. Internal combustion engine according to claim 11, characterized in that it has a multi-stage exhaust gas charging system ( 2 ) with a high-pressure turbine ( 6 ) comprehensive exhaust gas turbocharger ( 4 ) and a low-pressure turbine ( 7 ) second exhaust gas turbocharger ( 5 ), wherein the exhaust aftertreatment system ( 3 ) between the high-pressure turbine ( 6 ) and the low-pressure turbine ( 7 ) is switched.

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