KR20170113432A - Exhaust gas after-treatment system and internal combustion engine - Google Patents

Abstract

The exhaust gas aftertreatment system 3 of the internal combustion engine according to the present invention, that is, the SCR exhaust gas after-treatment system comprises an SCR catalytic converter 9 accommodated in a reaction chamber 10, Which has an exhaust gas feed line 8 leading to the SCR catalytic converter 9 and has an exhaust gas exhaust line 11 leading from the reaction chamber 10 and thus from the SCR catalytic converter 9, (16) attached to an exhaust gas supply line (8) for introducing an ammonia or ammonia precursor material into the exhaust gas, wherein the inlet device (16) is disposed upstream of the reaction chamber (10) or the SCR catalytic converter An exhaust aftertreatment system comprising a mixing section (18) provided by an exhaust gas feed line (18) on the downstream side of an inlet device (16) for mixing exhaust gas and a reducing agent, wherein in the reaction chamber (10) The SCR catalytic converter 9 is purged At least one blow of the to-down device 24 is disposed.

Description

[0001] EXHAUST GAS AFTER-TREATMENT SYSTEM AND INTERNAL COMBUSTION ENGINE [0002]

The present invention relates to an exhaust gas aftertreatment system for an internal combustion engine. The present invention also relates to an internal combustion engine having an exhaust gas aftertreatment system.

For example, in a combustion process in a stationary internal combustion engine employed in a power plant and in a combustion process in a non-internal combustion engine employed in a ship, for example, nitrogen oxides are formed which are typically coal, coal, It is formed during the combustion of fossil fuels containing sulfur such as crude oil, heavy oil, or light oil. For this reason, the above-described internal combustion engine is provided with an exhaust gas post-treatment system for purifying the exhaust gas exiting the internal combustion engine, in particular, for performing denitration.

In order to reduce the nitrogen oxides in the exhaust gas, so-called SCR catalytic converters are employed in exhaust gas aftertreatment systems, which are known in the art. In the SCR catalytic converter, selective catalytic reduction of nitrogen oxides occurs. In this case, ammonia (NH ₃ ) is required as a reducing agent for the reduction of nitrogen oxides. For this purpose, ammonia or an ammonia precursor material, such as, for example, urea, is introduced in liquid form into the exhaust gas upstream of the SCR catalytic converter, in which case the ammonia or ammonia precursor material is separated from the exhaust gas upstream of the SCR catalytic converter Mixed. To this end, in practice, a mixing section is provided between the inlet of the ammonia or ammonia precursor material and the SCR catalytic converter.

Although exhaust gas aftertreatment, especially nitrogen oxide reduction, has already been successfully accomplished using exhaust gas aftertreatment systems known in the art, there is a need to further improve the exhaust gas aftertreatment system. Particularly, there is a need to enable efficient exhaust gas post-treatment using the exhaust gas after-treatment system of compact design.

Starting from this point, the object of the present invention is based on the creation of an exhaust gas aftertreatment system for a new type of internal combustion engine and an internal combustion engine having such an exhaust gas aftertreatment system.

This problem is solved by an exhaust gas after-treatment system of an internal combustion engine according to claim 1. According to the present invention, at least one blow-down device serving to purge the SCR catalytic converter is disposed in the reaction chamber. This can prevent the SCR catalytic converter from being clogged as a result of soot particles being deposited in the SCR catalytic converter. A very efficient exhaust gas after-treatment using the above exhaust gas after-treatment system of compact design can be assured.

According to another advantageous refinement of the invention, the or each blow-down device is arranged on the surface of the SCR catalytic converter which extends transversely with respect to the flow direction, in particular transversely with respect to the direction of flow, On the upstream surface of the honeycomb body of the SCR catalytic converter extending in the direction of the vortex flow or vortex flow. This can very effectively prevent the SCR catalytic converter from being clogged as a result of soot particles being deposited in the SCR catalytic converter. Efficient exhaust gas purification can be ensured by using the exhaust aftertreatment system of compact design.

According to another advantageous refinement of the invention, the reaction chamber has a wall with a circular cross section, in particular a circular wall. This is desirable for the formation of a vortex flow or vortex flow. As a result, exhaust gas post-treatment can be performed very efficiently with a compact design.

According to another advantageous refinement of the invention, each blow-down device is arranged adjacent to a wall of a reaction chamber which is circular in cross-section, the blows come out of the wall and into the reaction chamber, Intersects the ejection cone of another blow-down device. This is desirable for the formation of a vortex flow or vortex flow and for all-zone purging of soot particles. As a result, exhaust gas post-treatment can be performed very efficiently with a compact design.

According to a further advantageous further development, the exhaust gas feed line passes through the downstream end towards the reaction chamber accommodating the SCR catalytic converter, and between the downstream end of the exhaust gas feed line in the reaction chamber and the SCR catalytic converter , And a device for increasing the exhaust gas back pressure is disposed on the upstream side of the SCR catalytic converter. With the aid of a device for increasing the exhaust gas back pressure upstream of the SCR catalytic converter, the exhaust gas flow upstream of the SCR catalytic converter is blocked, and as a result, in the circumferential direction and also in the radial direction, It can be achieved that the exhaust gas flow is uniformly supplied to the converter. Therefore, efficient purification of exhaust gas can be ensured by using the exhaust gas after-treatment system of compact design. Soot particles can also be deposited in the apparatus to increase the exhaust gas backpressure, in which case the soot particles no longer enter the zone of the SCR catalytic converter and do not block the SCR catalytic converter. It also serves to ensure efficient exhaust gas purification using exhaust gas aftertreatment systems of compact design.

The or each blow-down device is preferably disposed between the SCR catalytic converter and the device for increasing the exhaust gas back pressure in the reaction chamber. In this case, the or each blow-down device serves to purge at least the SCR catalytic converter and preferably further purge the device for increasing the exhaust gas back pressure. According to this other improvement example, a very efficient exhaust gas after-treatment is possible with a compact design.

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

Further preferred embodiments of the invention are obtained through the dependent claims and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the present invention will now be described in more detail with reference to the drawings, but are not limited thereto. In the drawings,
1 is a schematic perspective view of an internal combustion engine having an exhaust aftertreatment system according to the present invention;
2 is a detailed view of the exhaust aftertreatment system of FIG. 1;
Figure 3 is a detail view of Figure 2;
4 is a cross-sectional view of the detail of FIG.

The present invention relates to an exhaust gas aftertreatment system of an internal combustion engine, for example, a stationary internal combustion engine in a power plant or a non-fixed internal combustion engine employed in a ship. In particular, the exhaust aftertreatment system is employed in diesel engines of heavy oil-operated vessels.

1 shows an arrangement of an internal combustion engine 1 having an exhaust gas supercharging system 2 and an exhaust gas after-treatment system 3. As shown in Fig. The internal combustion engine 1 may be a non-fixed or stationary internal combustion engine, particularly a non-operational internal combustion engine of a ship. The exhaust gas exiting the cylinder of the internal combustion engine 1 is used in the exhaust gas supercharging system 2 to obtain the mechanical energy for compressing the supercharged air supplied to the internal combustion engine 1 from the thermal energy of the exhaust gas. Thus, Figure 1 shows an exhaust gas supercharging system 2 comprising a plurality of exhaust gas turbochargers, namely a first exhaust gas turbocharger 4 on the high pressure side and a second exhaust turbocharger 5 on the low pressure side The internal combustion engine 1 shown in Fig. The exhaust gas exiting the cylinder of the internal combustion engine 1 flows through the high pressure turbine 6 of the first exhaust gas turbocharger 4 initially and is expanded in this high pressure turbine, Is used to compress the supercharging air in the high pressure compressor of the first exhaust gas turbocharger (4). The second exhaust gas turbocharger 5 is disposed on the downstream side of the first exhaust gas turbocharger 4 as viewed in the flow direction of the exhaust gas so that the high pressure turbine 4 of the first exhaust gas turbocharger 4 6 are guided via the second exhaust gas turbocharger 5, that is, via the low pressure turbine 7 of the second exhaust gas turbocharger 5. In the low pressure turbine 7 of the second exhaust gas turbocharger 5 the exhaust gas is further expanded and the energy obtained in this process is supplied to the internal combustion engine 1 ) To the cylinder of the engine.

In addition to the exhaust gas supercharging system 2 including the exhaust gas turbochargers 4 and 5, the internal combustion engine 1 includes an exhaust gas aftertreatment system 3 which is an SCR exhaust gas aftertreatment system. The SCR exhaust gas after-treatment system 3 is connected between the high-pressure turbine 6 and the low-pressure turbine 7 of the first exhaust gas turbocharger 4 so that the high- The exhaust gas exiting the turbine 6 can be initially directed via the SCR exhaust gas aftertreatment system 3 before reaching the region of the low pressure turbine 7 of the second exhaust turbocharger 5 have.

1 shows an exhaust gas supply line 8 which is exhausted from the high pressure turbine 6 of the first exhaust gas turbocharger 4 and which is guided to the SCR catalytic converter 9 disposed in the reaction chamber 10, Lt; / RTI > 1 also shows an exhaust gas discharge line 11 serving to discharge the exhaust gas from the SCR catalytic converter 9 to the low pressure turbine 7 of the second exhaust gas turbocharger 5. [ The exhaust gas from the low-pressure turbine 7 flows via line 21, in particular outdoors. An exhaust gas feed line 8 leading to the reaction chamber 10 and thus to the SCR catalytic converter 9 disposed in the reaction chamber 10 and an exhaust gas feed line 8 from the reaction chamber 10 and thus from the SCR catalytic converter 9 The ensuing exhaust gas discharge line (11) is connected via a bypass (12) in which the blocking element (13) is integrated. With the blocking element 13 closed, the bypass 12 is closed, so that the exhaust gas does not flow via the bypass. In contrast, in particular, when the blocking element 13 is open, the exhaust gas passes through the bypass 12, that is to say through the reaction chamber 10 and thus into the reaction chamber 10, (9). ≪ / RTI > 2 shows the flow of the exhaust gas passing through the exhaust gas aftertreatment system 3 in the state of the bypass line 12 being closed through the blocking element 13, Passes through the downstream side end portion 15 toward the reaction chamber 10 and the exhaust gas in the region of the downstream side end portion 15 of the exhaust gas supply line 8 undergoes a flow direction change of about 180 °, It is evident in Fig. 2 that the exhaust gas is guided via the SCR catalytic converter 9 after this flow direction changeover.

The exhaust gas supply line 8 of the exhaust gas aftertreatment system 3 is fed with an inlet device 16 through which the reducing agent is introduced into the exhaust gas by the nitrogen oxide of the exhaust gas The ammonia or ammonia precursor material necessary to convert the ammonia or ammonia precursor material into the exhaust gas stream may be introduced into the exhaust gas flow. The inlet device 16 of this exhaust gas aftertreatment system 3 is preferably an injection nozzle through which the ammonia or ammonia precursor material is injected into the exhaust gas stream in the exhaust gas supply line 8. [ Figure 2 shows the cone 17 as injecting a reducing agent into the exhaust gas stream in the zone of the exhaust gas supply line 8.

A section of the exhaust gas aftertreatment system 3, which is located downstream of the inlet device 16 and upstream of the SCR catalytic converter 9, as viewed in the exhaust gas flow direction, is referred to as a mixing section. Specifically, the exhaust gas supply line 8 provides a mixing section 18 on the downstream side of the inlet device 16, in which the exhaust gas is mixed with a reducing agent on the upstream side of the SCR catalytic converter 9 .

The exhaust gas supply line 8 communicates with the reaction chamber 10 through the downstream end 15. A baffle element 20 displaceable with respect to the downstream side end portion 15 of the exhaust gas supply line 8 is attached to the downstream side end portion 15 of the exhaust gas supply line 8. In the illustrated exemplary embodiment, the baffle element 20 is linearly displaceable relative to the downstream end 15 of the exhaust gas supply line 8 leading to the reaction chamber 10 side. The baffle element 20 is arranged downstream of the exhaust gas supply line 8 to block the exhaust gas supply line 8 at the downstream side end 15 or to open the exhaust gas supply line at the downstream side end 15. [ And is displaceable with respect to the side end portion (15). Specifically, when the baffle element 20 cuts off the exhaust gas supply line 8 at the downstream end 15, the exhaust gas is supplied to the SCR catalytic converter 9 or the SCR catalytic converter 9 It is preferable that the blocking element 13 of the bypass 12 is opened to guide the reaction chamber 10 completely through. Specifically, when the baffle element 20 opens the downstream end 15 of the exhaust gas supply line 8, the blocking element 13 of the bypass 12 can be fully closed or at least partially open .

Specifically, when the baffle element 20 opens the downstream side end 15 of the exhaust gas supply line 8, the baffle element 20 is moved to the downstream side end 15 of the exhaust gas supply line 8, The relative position is determined by the flow rate of the exhaust gas, particularly the exhaust gas mass flow rate through the exhaust gas supply line 8 and / or the temperature of the exhaust gas in the exhaust gas supply line 8 and / Depending on the amount of reducing agent present.

Another function of the baffle element 20 in the state that the downstream end 15 of the exhaust gas supply line 8 is open is that any droplet of reducing agent present in the exhaust gas flow is directed to the area of the SCR catalytic converter 9 In which the droplets of the reducing agent reach the baffle element and are caught and atomized in the baffle element. Particularly in the region of the baffle element 20 by the relative position of the baffle element 20 to the downstream end 15 of the exhaust gas supply line 8 in the state that the downstream side end portion 15 is open The exhaust gas which is redirected in the region of the downstream end 15 of the exhaust gas supply line 8 flows toward the section of the SCR catalytic converter 9 disposed more radially inwardly or radially outwardly More, oriented or steered.

According to a preferred embodiment, the exhaust gas supply line 8 is funnel-shaped in the region of the downstream end 15 to form a diffuser. Therefore, the flow cross section of the exhaust gas supply line 8 is increased in the region of the downstream side end portion 15, and particularly in the exhaust gas flow direction as seen in FIG. 2, , The flow cross section of the exhaust gas supply line is first reduced. 2 shows that the flow cross section of the exhaust gas supply line 8 is initially substantially constant on the downstream side of the reducing agent inlet device 16 when viewed in the exhaust gas flow direction, And eventually extends in the region of the downstream end 15.

In this case, the flow cross-section is enlarged at the downstream side end portion 15 of the exhaust gas supply line 8 because the exhaust gas supply line 8 tapered in front of the downstream side end portion 15 is initially It is preferable to be carried out via a section of the exhaust gas supply line 8 that is shorter than the passing section.

Preferably the baffle element 20 is curved at the side 22 facing the exhaust gas supply line 8 and preferably curved in a bell to form a flow guide for the exhaust gas. The side surface on the radially inner section of the baffle element 20 facing the downstream end 15 of the exhaust gas supply line 8 is located downstream of the exhaust gas supply line 8, The distance to the side end 15 is shorter than the side on the radially outer section of the baffle element 20. Thus, the baffle element 20 is drawn or curved toward the downstream end 15 of the exhaust gas supply line 8 at the center against the flow direction of the exhaust gas.

The exhaust gas supply line 8 is connected to the reaction chamber 10 which receives the SCR catalytic converter 9 through the downstream end portion 15 thereof. 2, the exhaust gas supply line 8 passes through the lower side of the reaction chamber 10 and is adjacent to the upper side 23 of the reaction chamber 10 through the downstream side end portion 15 thereof And the exhaust gas exiting the exhaust gas supply line at the downstream end 15 as described above is diverted to 180 before it flows subsequently through the SCR catalytic converter 9. [

3, the device 25 for increasing the exhaust gas back pressure is connected to the SCR catalytic converter 9 between the downstream end 15 of the exhaust gas supply line 8 and the SCR catalytic converter 9, As shown in Fig. The apparatus 25 for increasing the exhaust gas back pressure may be, for example, a grid, a perforated plate, or the like.

The exhaust gas flow on the upstream side of the SCR catalytic converter 9 is blocked with the aid of the device 25 for increasing the exhaust gas back pressure upstream of the SCR catalytic converter 9 and consequently in the circumferential direction Also, when viewed in the radial direction, it can be achieved that the exhaust gas flow is uniformly supplied to the SCR catalytic converter 9. [

The device 25 for increasing the exhaust gas back pressure also has the advantage that soot particles contained in the exhaust gas can be deposited in this device. The soot particles deposited in the device 25 for increasing the exhaust gas back pressure no longer enter the zone of the SCR catalytic converter 9 and do not block the SCR catalytic converter, i.e. the honeycomb 27 of the SCR catalytic converter. 3 and 4 show a plurality of honeycomb bodies 27 of the SCR catalytic converter 9 having a circular section.

The apparatus 25 for increasing the exhaust gas back pressure also has a maximum of 2 times, preferably at most 1 times, and very preferably at most 2 times, Flow cross-section corresponding to a maximum of 0.5 times. In this way, on the one hand, it can be ensured that the exhaust gas flows out evenly to the SCR catalytic converter 9, and on the other hand, in the region of the device 25 which increases the exhaust gas back pressure, So that it can be ensured that it no longer reaches the region of the SCR catalytic converter 9.

Preferably, the thickness or length of the device 25 for increasing the exhaust gas back pressure as viewed in the flow direction or the exhaust gas flow direction and the thickness or length of the SCR catalytic converter 9 or the SCR catalytic converter 9, as viewed in the flow direction or the exhaust gas flow direction, The ratio between the thickness or the length of the honeycomb body 27 of the honeycomb body 9 is at least 1:50, preferably at least 1: 100, and very preferably at least 1: 200.

Preferably, the distance corresponding to the distance between the device 25 for increasing the exhaust gas back pressure and the SCR catalytic converter 9 when viewed in the flow direction or the exhaust gas flow direction and the distance corresponding to the distance between the SCR catalytic converter 9 Or the ratio of the thickness or the length of the honeycomb body 27 of the SCR catalytic converter 9 to a maximum of 2: 1, preferably 1: 1, and very preferably 1: 2.

It is possible to ensure that the exhaust gas is uniformly supplied to the SCR catalytic converter 9 by the device 25 for increasing the exhaust gas back pressure disposed in the reaction chamber 10. [ By increasing the exhaust gas back pressure, the exhaust gas flow is blocked, thereby ensuring an even distribution of the exhaust gas to the SCR catalytic converter 9. Another advantage of the device 25 for increasing exhaust backpressure is that it also assumes the function of a pre-separator in which soot particles contained in the exhaust gas can be deposited. Because of this, it can be prevented that the particles reach the SCR catalytic converter 9 without interfering with the particles, blocking the SCR catalytic converter.

In the reaction chamber 10, at least one blow-down device 24, which serves to purge the SCR catalytic converter 9, is disposed. In the illustrated preferred exemplary embodiment, the or each blow-down device 24 is disposed in a reaction chamber 10 having an SCR catalytic converter 9 and, in addition, The device 25 is accommodated and the or each blow-down device 24 is arranged between the device 25 for increasing the exhaust gas back pressure and the SCR catalytic converter 9 when viewed in the flow direction of the exhaust gas Respectively. The or each blow-down device 24 is preferably an air nozzle. To prevent clogging of the SCR catalytic converter 9 and also to prevent clogging of the device 25 which preferably increases the exhaust gas back pressure, the or each blow-down device 24 comprises at least the SCR catalytic converter 9 , And preferably also serves to purge the device 25 for increasing the exhaust gas back pressure. The exhaust gas recirculation system according to the present invention can be used for purifying the SCR catalytic converter 9, The or each blow-down device 24 preferably comprises a SCR catalytic converter 9 (not shown) extending on the surface of the SCR catalytic converter 9 transversely to the direction of flow, On the upstream surface of the honeycomb body 27, in a manner inducing vortex flow or vortex flow.

Here, FIG. 4 shows a schematic view of the catalytic converter 9 in the reaction chamber 10, that is, on the upstream surface of the SCR catalytic converter 9 extending perpendicularly to the flow direction or the exhaust gas flow direction, Down device 24 is preferably oriented in such a manner that a vortex flow or a vortex flow is also generated on the downstream surface of the device 25 for increasing the exhaust gas back pressure that extends perpendicularly to the direction Down device 24 in which, in each case, the surfaces are facing the or each blow-down device 24, respectively. The purging of soot particles from the SCR catalytic converter 9, i.e. from the honeycomb body 27 of the SCR catalytic converter, and preferably also from the device 25 which increases the exhaust gas backpressure, by vortex flow or vortex flow, It can happen very efficiently.

The reaction chamber 10 in which the SCR catalytic converter 9 and preferably the exhaust gas backpressure increasing device 25 are accommodated is preferably circular in cross section and in particular circular, And a wall 19 extending between the lower side 22 and the upper side 23. An inner space of the reaction chamber 10 accommodating at least the catalytic converter 9 is defined inside the wall 19 having at least a round or circular cross section. A device (25) that serves to purgate the SCR catalytic converter (9) and preferably also increases the exhaust gas back pressure by combining said wall (19) with the orientation of said or each blow- , Vortex flow or vortex flow can be very advantageously constructed in the reaction chamber 10 with respect to the soot particles being deposited on the purging objects.

Preferably, at least three blow-down devices 24, preferably at least four blow-down devices 24, are disposed in the reaction chamber 10.

Here, the blow-down device 24 is disposed adjacent to the reaction chamber 10 having a circular section, and the blown air or the compressed air comes out of the wall 19 of the reaction chamber and enters into the reaction chamber 10, The ejection cone 26 intersects the ejection cone 26 of at least one other blow-down device 24 and is thereby partially superimposed. For this reason, on the above-mentioned surfaces, the device 25 for increasing the SCR catalytic converter 9 and preferably the exhaust gas backpressure can also be implemented or ensured for full-zone purging.

According to the present invention, exhaust gas post-treatment can be effectively performed with a compact design.

In the case of the internal combustion engine 1 of FIG. 1, the exhaust gas aftertreatment system 3 is arranged in an upright position on the upstream side of the exhaust gas supercharging system 2. Access to the cylinder of the internal combustion engine 1 is free, but the accessibility of the exhaust gas turbochargers 4 and 5 is limited. However, when the maintenance work is required for the exhaust gas turbochargers 4 and 5, the reaction chamber 10 can be simply disassembled.

In addition to the arrangement in which the exhaust gas aftertreatment system 3 is arranged upright on the upstream side of the exhaust gas supercharging system 2 shown in FIG. 1, beside the exhaust gas supercharging system 2, It is also possible to arrange the light emitting element 3 horizontally at an inclination of 90 占 However, in the case of this horizontal arrangement, the length of the arrangement is increased. However, in this case, there is no need to disassemble the reaction chamber 10, so that the internal combustion engine 1 and the exhaust gas supercharging system 2 can be used for maintenance work without restriction.

1: Internal combustion engine 2: Exhaust gas supercharging system
3: Exhaust gas aftertreatment system 4: Exhaust gas turbocharger
5: Exhaust gas turbocharger 6: High pressure turbine
7: Low pressure turbine 8: Exhaust gas supply line
9: SCR catalytic converter 10: reaction chamber
11: Exhaust gas discharge line 12: Bypass
13: Blocking element 14: Exhaust gas guide
15: end 16: inlet device
17: injection cone 18: mixing section
19: wall 20: baffle element
21: line 22: side
23: side 24: blow-down device
25: Apparatus for increasing the exhaust gas back pressure
26: ejection cone 27: honeycomb body

Claims (12)

An exhaust gas aftertreatment system (3) of an internal combustion engine, that is, an SCR exhaust gas aftertreatment system of an internal combustion engine, comprises an SCR catalytic converter (9) accommodated in a reaction chamber (10) And an exhaust gas discharge line 11 leading from the reaction chamber 10 and thus from the SCR catalytic converter 9 and having an exhaust gas feed line 8 leading to an SCR catalytic converter 9, And an inlet device 16 attached to the exhaust gas supply line 8 for introducing an ammonia or ammonia precursor material into the exhaust gas. The exhaust gas is supplied from the upstream side of the reaction chamber 10 or the SCR catalytic converter 9, An exhaust aftertreatment system comprising a mixing section (18) provided by an exhaust gas supply line (8) on the downstream side of an inlet device (16) for mixing a gas and a reducing agent, wherein the reaction chamber (10) The catalytic converter 9 is purged At least one blow of the to-down device 24, the exhaust gas aftertreatment system, characterized in that it is disposed. 3. A blower according to claim 1, wherein said or each blow-down device (24) is arranged in a transverse direction with respect to the direction of flow, in particular on the surface of the SCR catalytic converter (9) Or vortex flow of the exhaust gas. 3. The SCR catalytic converter (9) as claimed in claim 2, wherein the or each blow-down device (24) comprises at least one blow-down device (24) of a SCR catalytic converter (9) extending transversely with respect to the direction of flow, On the upstream side surface, is oriented in such a way as to induce vortex flow or vortex flow. The exhaust gas aftertreatment system according to any one of claims 1 to 3, wherein the reaction chamber (10) has a wall (19) having a circular cross section, in particular a circular wall. 5. A method according to claim 4 wherein each blow-down device (24) is disposed adjacent a wall (19) of a reaction chamber (10) having a circular cross section and the blows exit the wall (19) , I.e. the ejection cone (26) intersects the ejection cone (26) of at least one other blow-down device (24). The exhaust gas purifying apparatus according to any one of claims 1 to 5, wherein the exhaust gas supply line (8) communicates with the reaction chamber (10) through the downstream end (15) An apparatus 25 for increasing the gas back pressure is disposed on the upstream side of the SCR catalytic converter 9 between the downstream end 15 of the exhaust gas supply line 8 and the SCR catalytic converter 9. [ Exhaust gas aftertreatment system. 7. A method according to claim 6, characterized in that said or each blow-down device (24) is arranged between the device (25) increasing the exhaust gas back pressure in the reaction chamber (10) and the SCR catalytic converter The exhaust gas aftertreatment system. 8. A device according to claim 6 or 7, characterized in that the device (25) for increasing the exhaust gas back pressure has a maximum of 2 times, preferably at most 1 times, and most preferably at most 1 times the free-flowing cross section of the SCR catalytic converter (9) Flow cross-section corresponding to 0.5 times the free-flow cross-section. 9. A method according to any one of claims 6 to 8, wherein the thickness or length of the device (25) for increasing the exhaust gas back pressure when viewed in the direction of flow and the thickness or length of the SCR catalytic converter (9) Length of at least 1:50, preferably at least 1: 100, and very preferably at least 1: 200. 10. A method according to any one of claims 6 to 9, characterized in that the distance corresponding to the distance between the device (25) increasing the exhaust gas back pressure and the SCR catalytic converter (9) when viewed in the direction of flow, The ratio between the thickness or the length of the SCR catalytic converter 9 when viewed corresponds to a maximum of 2: 1, preferably 1: 1, and very preferably 1: 2. An internal combustion engine (1) comprising an exhaust gas aftertreatment system (3) according to any one of claims 1 to 10, in particular an internal combustion engine operated by light or heavy oil. 12. An internal combustion engine according to claim 11, characterized in that the internal combustion engine comprises a first exhaust gas turbocharger (4) comprising a high pressure turbine (6) and a second exhaust gas turbocharger (5) Pressure turbine (6) and the low-pressure turbine (7), wherein the exhaust gas after-treatment system (3) is connected between the high-pressure turbine (6) and the low-

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