DE102016113396A1 - Exhaust after treatment system and internal combustion engine - Google Patents

Abstract

Exhaust after-treatment system (3) of an internal combustion engine, namely SCR exhaust aftertreatment system, with an SCR catalyst (9), with an exhaust gas supply line (8) leading to the SCR catalytic converter (9) and with an exhaust gas discharge line (11) leading away from the SCR catalytic converter (9). , with a feed device (16) assigned to the exhaust gas feed line (8) for introducing a reducing agent, in particular ammonia or an ammonia precursor substance, into the exhaust gas, and with a mixing section (18) provided downstream of the feed device (16) from the exhaust gas feed line (8) ) for mixing the exhaust gas with the reducing agent upstream of the SCR catalyst (9). The exhaust gas supply line (8) opens at a downstream end (15) into a SCR catalytic converter (9) receiving the reactor chamber (10), wherein the exhaust gas supply line (8) adjacent to the downstream end (15) has openings (27) having an inlet allow exhaust gas into the reactor space (10) upstream of the downstream end (15) of the exhaust gas supply line (8).

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 (NH ₃ ) 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, wherein the ammonia or the ammonia precursor substance upstream of the SCR catalyst with the exhaust gas is mixed. 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 aftertreatment can already be successfully carried out with exhaust aftertreatment systems known from practice, there is a need to further improve the exhaust aftertreatment systems. In particular, there is a need for a compact design of such exhaust aftertreatment systems.

On this basis, the present invention has the object to provide a novel exhaust aftertreatment system. This object is achieved by an exhaust aftertreatment system according to claim 1. According to the invention, the exhaust gas feed line opens at a downstream end into a reactor space receiving the SCR catalyst, wherein the exhaust gas feed line has openings adjacent to the downstream end, which allow an entry of exhaust gas into the reactor space upstream of the downstream end of the exhaust gas feed line. With a compact design, effective exhaust aftertreatment can be guaranteed.

According to an advantageous development, an exhaust gas flow flowing into the reactor space via the downstream end of the exhaust gas feed line and an exhaust gas flow flowing through the openings into the reactor space are miscible in the reactor space and can be conducted via the SCR catalyst. With a compact design, effective exhaust aftertreatment can be guaranteed.

According to an advantageous development, the exhaust gas inlet and the exhaust gas outlet attack at a common side of the reactor space, wherein the exhaust gas discharge at this common side of the reactor space downstream of the SCR catalyst opens into the reactor space, and wherein the exhaust gas supply to the downstream end of one of these common Side of the reactor chamber opposite side of the reactor chamber exhaust gas upstream side of the SCR catalyst opens into the reactor chamber, and wherein the exhaust gas supply line extends with the mixing passage through the SCR catalyst. With a compact design, effective exhaust aftertreatment can be guaranteed.

The exhaust gas supply line preferably has the openings in a section which is positioned between the SCR catalytic converter and the downstream end of the exhaust gas supply line, so that the exhaust gas flowing through the openings opens into the reactor chamber on the exhaust gas flow side upstream of the SCR catalytic converter. With a compact design, effective exhaust aftertreatment can be guaranteed.

According to a further advantageous development, a baffle element cooperates with the downstream end of the exhaust gas supply line, which deflects the exhaust gas flow exiting via the downstream end from the exhaust gas supply line. With a compact design, effective exhaust aftertreatment can be guaranteed.

The internal combustion engine according to the invention is defined in claim 9.

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 ; and

4 : a further detail of the exhaust aftertreatment system according to the invention.

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 unsteady or stationary internal combustion engine, in particular a transiently operated 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 in the illustrated embodiment between the high-pressure turbine 6 of the first compressor 5 and the low-pressure turbine 7 the second exhaust gas turbocharger 5 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 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 26 especially outdoors. The invention is not limited to internal combustion engines having such a two-stage turbocharging system. The invention can also be used in internal combustion engines with a single-stage exhaust gas turbocharging system, wherein the SCR catalyst 9 upstream or downstream of the turbine of the exhaust gas turbocharger may be connected in the exhaust gas stream.

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 via a bypass line 12 coupled, in which a shut-off 13 is integrated. When the shut-off device is closed 13 is the bypass line 12 closed so that no exhaust gas can flow over the same. Then, however, when the obturator 13 open, can via the bypass line 12 Exhaust gas flow, past the reactor room 10 and therefore past the reactor room 10 positioned SCR catalyst 9 ,

As stated, the exhaust gas supply line 8th as well as the exhaust gas discharge 11 over a bypass 12 can be coupled to open bypass 12 Exhaust gas at the reactor room 10 and therefore on the SCR catalyst 9 passing out. It is envisaged that the exhaust gas inlet 8th and the exhaust gas discharge 11 on a common page 28 of the SCR catalyst 9 receiving reactor space 10 attack. This allows for a long bypass line of the bypass 12 between the exhaust gas supply line 8th and the exhaust gas discharge 11 , which is about the the SCR catalyst 9 receiving reactor space 10 extends around, be waived. The bypass 12 can therefore be made short and compact, so that in a compact design effective exhaust aftertreatment is possible.

The exhaust gas supply line 8th and the exhaust gas discharge 11 grab the common side 28 of the SCR catalyst 9 receiving reactor space 10 such that the exhaust gas discharge 11 on this common site 28 of the reactor space 10 exhaust gas flow side downstream of the SCR catalyst 9 in the reactor room 10 opens, and that the exhaust gas supply line 8th with a downstream end 15 at one of these common sites 28 of the reactor space 10 opposite side 29 of the reactor space 10 exhaust gas flow side upstream of the SCR catalyst 9 in the reactor room 10 empties. The exhaust gas supply line 8th extends through the SCR catalyst 9 therethrough. The exhaust gas discharge 11 encloses in sections concentrically radially outside the exhaust gas supply line 8th , in an area outside the reactor room 10 adjacent to the page 28 the same goes. The bypass 12 is formed in the embodiment shown in a region which is positioned adjacent to the region in which the exhaust gas discharge 11 the exhaust gas supply line 8th concentrically surrounds. This is an effective exhaust aftertreatment possible with a compact design.

In contrast, it is also possible that the bypass 12 is formed in the area in which the exhaust gas discharge 11 the exhaust gas supply line 8th concentric outside surrounds.

The exhaust gas supply line 8th the exhaust aftertreatment system 3 is a loading device 16 assigned, via which a reducing agent can be introduced into the exhaust gas stream, in particular ammonia (NH ₃ ) or an ammonia precursor substance, which is needed in the region 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 lies, is called a mixed route 18 or decomposition path. 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 mixing route 18 and thus the exhaust gas supply line 8th are outside sections of the SCR catalyst 9 , here in the form of individual catalyst modules, enclosed. In this section, the SCR catalyst heats up 9 the mixing section 18 , The flow directions of the exhaust gas in the mixing section 18 and the SCR catalyst 9 are opposite.

The exhaust gas supply line 8th flows with the downstream end 15 in the reactor room 10 , The exhaust gas supply line 8th has adjacent to the downstream end 15 breakthroughs 27 on, the entry of exhaust gas into the reactor space 10 upstream of the downstream end 15 the exhaust gas supply line 8th enable. One over the downstream end 15 the exhaust gas supply line 8th in the reactor room 10 flowing exhaust gas flow and one over the breakthroughs 27 in the reactor room 10 flowing exhaust gas flow are in the reactor space 10 upstream of the SCR catalyst 9 miscible and over the SCR catalyst 9 feasible. 2 and 4 clarify with arrows 14 the flow of exhaust gas. This is an extremely effective exhaust aftertreatment possible with extremely compact design.

The exhaust gas supply line 8th has the breakthroughs 27 in a section between the SCR catalyst 9 and the downstream end 16 the exhaust gas supply line 8th is positioned. That about the breakthroughs 27 flowing exhaust gas flows on the exhaust gas flow side upstream of the SCR catalytic converter 9 in the reactor room 10 , This is an extremely effective exhaust aftertreatment possible with extremely compact design. The exhaust gas supply line 8th has the breakthroughs 27 in a section of the mixing route 18 or decomposition path upstream of the downstream end 15 the exhaust gas supply line 8th on, preferably in the last or rear third, more preferably in the last or rear quarter of the mixing section 18 or decomposition path. This is an extremely effective exhaust aftertreatment possible with extremely compact design.

The SCR catalyst 9 and at least partially the mixing section 18 or decomposition path are both in the reactor space 10 and thus housed in a common housing, the walls of the reactor space 10 form.

the downstream end 15 the exhaust gas supply line 8th is a baffle element 19 associated, which is preferably relative to the downstream end 15 the exhaust gas supply line 8th is relocatable. In the illustrated preferred embodiment, the baffle element 19 relative to the downstream end 15 the exhaust gas supply line 8th which is in the reactor room 10 flows, in the direction of the double arrow 25 linearly displaceable, in particular by means of a pneumatic adjusting cylinder 20 that has a piston rod 21 at the impact element 19 attacks and gets through a wall 22 of the reactor space 10 in the area of the page 29 the same extends. A seal 23 seals the piston rod 21 of the pneumatic cylinder 20 where the same wall 22 of the reactor space 10 penetrates. About the relative position of the impact element 19 to the downstream end 15 the exhaust gas supply line 8th 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 19 is deflected, more toward radially inwardly positioned sections or more towards radially outwardly positioned sections of the SCR catalyst 9 is steered and how much exhaust gas through the breakthroughs 27 in relation to the downstream end 15 the exhaust pipe 8th flows.

The impact element 19 can be at least at one of the downstream end 15 the exhaust gas supply line 8th facing side to form a flow guide for the exhaust to be curved, preferably curved like a bell. In particular 3 and 4 to be taken that side 24 of the baffle element 19 that is the downstream end 15 the exhaust gas supply line 8th facing, at a radially inner portion of the impact member 19 a smaller distance to the downstream end 15 the exhaust gas supply line 8th as at a radially outer portion thereof.

The impact element 19 is in the center of the page 24 towards the downstream end 15 the exhaust gas supply line 8th retracted or curved against the flow direction of the exhaust gas. Drops of liquid reducing agent present in the exhaust stream do not flow through the openings 27 but hit the downstream end 15 the exhaust gas supply line 8th facing side 24 of the baffle element 19 and are trapped and atomized there to prevent such drops of liquid reductant from entering the region of the SCR catalyst 9 reach.

The impact element 19 prevents at low pressure loss, a demolition of the exhaust gas flow downstream of the downstream end 15 the exhaust gas supply line 8th , A distance between the baffle element 19 and the downstream end 15 the exhaust gas supply line 8th is in particular at least 100 mm, to a possible low-pressure loss deflection of the exhaust gas flow in the region of the impact element 19 to ensure, with a pressure loss of less than 10 mbar. In the area of the impact element 19 and thus the page 29 of the reactor space 10 Exhaust gas experiences a flow deflection of 180 ° or approximately 180 °.

The impact element 19 can be in the area of the downstream end 15 the exhaust gas supply line 8th facing side 24 have a catalytic coating to improve the exhaust aftertreatment.

According to one embodiment of the invention, 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 section over which the exhaust gas supply line 8th in front of the downstream end 15 initially rejuvenated. How best 4 can be taken, is the expansion of the downstream end 15 the exhaust gas supply line 8th and the bell-like contouring of the page 24 of the baffle element 19 preferably formed continuously or steadily, ie without discontinuities.

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.

The invention is used in particular in internal combustion engines operated with excess air, preferably in marine diesel engines operated with heavy oil or residual oil.

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 line

13

shutoff

14

exhaust system

15

The End

16

introducing device

17

Injection cone

18

mixing section

19

baffle

20

pneumatic cylinder

21

piston rod

22

wall

23

poetry

24

page

25

displacement direction

26

management

27

breakthrough

28

page

29

page

Claims (13)

Exhaust aftertreatment system ( 3 ) of an internal combustion engine, namely SCR exhaust aftertreatment system of an internal combustion engine, with an SCR catalyst ( 9 ), with an SCR catalyst ( 9 ) leading exhaust gas supply ( 8th ) and with one 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 SCR catalyst ( 9 ), characterized in that the exhaust gas supply line ( 8th ) with a downstream end ( 15 ) into an SCR catalyst ( 9 ) receiving reactor space ( 10 ), and that the exhaust gas supply line ( 8th ) adjacent to the downstream end ( 15 ) Breakthroughs ( 27 ), which has an inlet of exhaust gas into the reactor space ( 10 ) upstream of the downstream end ( 15 ) of the exhaust gas supply line ( 8th ) enable. Exhaust gas after-treatment system according to claim 1, characterized in that one via the downstream end ( 15 ) of the exhaust gas supply line ( 8th ) into the reactor space ( 10 ) flowing exhaust gas flow and a through the openings ( 27 ) into the reactor space ( 10 ) flowing exhaust gas flow in the reactor space ( 10 ) upstream of the SCR catalyst ( 9 ) and via the SCR catalyst ( 9 ) are feasible. Exhaust after-treatment system according to claim 1 or 2, characterized in that with the downstream end ( 15 ) of the exhaust gas supply line ( 8th ) an impact element ( 19 ) which cooperates via the downstream end ( 15 ) from the exhaust gas supply line ( 8th ) deflecting exhaust gas flow. Exhaust gas after-treatment system according to claim 3, characterized in that the impact element ( 19 ) relative to the downstream end ( 15 ) of the exhaust gas supply line ( 8th ) is displaceable. Exhaust after-treatment system according to one of claims 1 to 4, characterized in that the exhaust gas feed line ( 8th ) and the exhaust gas discharge ( 11 ) on a common page ( 28 ) of the SCR catalyst ( 9 ) receiving reactor space ( 10 ) that the exhaust gas discharge ( 11 ) on this common page ( 28 ) of the reactor space ( 10 ) downstream of the SCR catalyst ( 9 ) into the reactor space ( 10 ), that the exhaust gas supply line ( 8th ) with the downstream end ( 15 ) on one of these common pages ( 28 ) of the reactor space ( 10 ) opposite side ( 29 ) of the reactor space ( 10 ) downstream of the SCR catalyst ( 9 ) into the reactor space ( 10 ), wherein the exhaust gas feed line ( 8th ) with the mixing section ( 18 ) through the SCR catalyst or, in the case of several SCR catalysts, through the range of SCR catalysts ( 9 ) extends therethrough. Exhaust after-treatment system according to claim 5, characterized in that the exhaust gas supply line ( 8th ) the breakthroughs ( 27 ) in a section between the SCR catalyst ( 9 ) and the downstream end ( 16 ) of the exhaust gas supply line ( 8th ) is positioned. Exhaust gas after-treatment system according to claim 6, characterized in that via the openings ( 27 ) exhaust gas flow downstream of the SCR catalyst ( 9 ) into the reactor space ( 10 ) opens. Exhaust after-treatment system according to one of claims 5 to 7, characterized in that exhaust gas flows in the region of the mixing section ( 18 ) and in the area of the SCR catalyst ( 9 ) are opposite. Exhaust gas aftertreatment system according to one of claims 5 to 8, characterized in that walls of the reactor space ( 10 ) for the SCR catalyst ( 9 ) and at least sections of the mixing section ( 18 ) form a common housing. Exhaust after-treatment system according to one of claims 1 to 9, characterized in that between the exhaust gas supply line ( 8th ) and the exhaust gas discharge ( 11 ) a bypass ( 12 ) to the SCR Catalyst ( 9 ) or reactor space ( 10 ) is formed, wherein in the bypass ( 12 ) a shut-off element ( 13 ) is switched. Internal combustion engine ( 1 ), in particular with a diesel fuel or with a heavy fuel oil-fueled internal combustion engine, with an exhaust aftertreatment system ( 3 ) according to one of claims 1 to 10. Internal combustion engine according to claim 11, characterized in that the exhaust aftertreatment system ( 3 ) upstream of at least one exhaust gas turbocharger ( 5 ) is attached. Internal combustion engine according to claims 11 and 12, 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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