JP6843674B2 - Exhaust gas aftertreatment system and internal combustion engine - Google Patents

Description

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

For example, in a combustion process in a stationary internal combustion engine used in a power plant and in a non-stationary internal combustion engine used in a ship, for example, nitrogen oxides are generated, and these nitrogen oxides are generated. It typically occurs during combustion of fossil fuels containing sulfur, such as coal, bituminous coal, brown coal, petroleum, heavy oil, or diesel fuel. Therefore, such an internal combustion engine is provided with an exhaust gas aftertreatment system used for purifying the exhaust gas discharged from the internal combustion engine, particularly denitrification.

In order to reduce nitrogen oxides in exhaust gas, a so-called SCR catalytic converter is first used in an exhaust gas aftertreatment system known in practice. In the SCR catalytic converter, selective catalytic reduction of nitrogen oxides is carried out, and ammonia (NH ₃ ) is required as a reducing agent for the reduction of nitrogen oxides. For this purpose, ammonia or urea, which is an ammonia precursor, is introduced into the exhaust gas in the form of a liquid upstream of the SCR catalytic converter, and ammonia or the ammonia precursor is mixed with the exhaust gas upstream of the SCR catalytic converter. .. For this purpose, in practice, a mixing section is provided between the introduction of ammonia or ammonia precursor and the SCR catalytic converter.

Exhaust gas post-treatment, especially the reduction of nitrogen oxides, has already been successfully implemented using well-known exhaust gas post-treatment systems, including SCR catalytic converters, but the exhaust gas after-treatment system needs to be further improved. There is sex. In particular, when the structure of such an exhaust gas aftertreatment system is miniaturized, there is a need to enable effective exhaust gas aftertreatment and effective operation of an internal combustion engine having an exhaust gas aftertreatment system.

Based on such a necessity, an object of the present invention is to create 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 the exhaust gas aftertreatment system of the internal combustion engine according to claim 1. According to the present invention, the exhaust gas supply conduit and / or the reaction chamber that receives the SCR catalytic converter and / or the exhaust gas discharge conduit is formed so as to have at least a double wall. Thereby, too much thermal energy of the exhaust gas can be prevented from being absorbed by the exhaust gas supply conduit and / or the reaction chamber and / or the exhaust gas discharge conduit, leading to a decrease in temperature. The thermal energy remains in the exhaust gas. This is advantageous to enable effective exhaust gas aftertreatment and effective operation of an internal combustion engine having an exhaust gas aftertreatment system.

According to a favorable further development, the first wall of the exhaust gas supply conduit and / or the first wall of the reaction chamber and / or the first wall of the exhaust gas discharge conduit is the exhaust gas supply conduit and / or reaction. At the dominant pressure in the chamber and / or the exhaust conduit, each wall has a thickness designed to withstand the respective pressure. A second wall is preferably arranged on the surface of each first wall facing the flow of exhaust gas to form a gap, and the thickness of the second wall is the thickness of each first wall. Less than the thickness. Preferably, a third wall is additionally arranged on the surface of each first wall that faces the flow of exhaust gas, and the thickness of the third wall is the thickness of each first wall. Greater than thickness. Thereby, effective exhaust gas aftertreatment and effective operation of an internal combustion engine having an exhaust gas aftertreatment system can be guaranteed.

According to a favorable further development, the product of the mass of each first wall and the heat capacity is greater than the corresponding product of each second wall. Further, preferably, the product of the mass of each first wall and the heat capacity is smaller than the corresponding product of each third wall. This is advantageous to ensure effective exhaust gas aftertreatment and effective operation of the internal combustion engine having the exhaust gas aftertreatment system.

According to another advantageous further development, the ratio of the thickness of each first wall to the thickness of each second wall is at least 10: 3, preferably at least 10: 2, particularly preferably at least 10 :. It is 1. This is advantageous to ensure effective exhaust gas aftertreatment and effective operation of the internal combustion engine having the exhaust gas aftertreatment system.

According to another advantageous further development, the ratio of the thickness of each first wall to the thickness of each third wall is at least 1: 5, preferably at least 1: 7, and particularly preferably at least 1: It is 10. This is advantageous to ensure effective exhaust gas aftertreatment and effective operation of the internal combustion engine having the exhaust gas aftertreatment system.

According to another advantageous further development, the thickness of the void between the first wall and the second wall and / or the thickness of the void between the first wall and the third wall is , At least 2 mm, preferably at least 4 mm, particularly preferably at least 6 mm. This is advantageous to ensure effective exhaust gas aftertreatment and effective operation of the internal combustion engine having the exhaust gas aftertreatment system.

The internal combustion engine according to the present invention is defined in claim 13.

Particularly preferably, the internal combustion engine has a multi-stage exhaust gas supercharging system including a first exhaust gas turbocharger including a high-pressure turbine and a second exhaust gas turbocharger including a low-pressure turbine. It is connected between the high pressure turbine and the low pressure turbine.

Preferred further developments of the present invention will become apparent from the dependent claims and the following description. Examples of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

It is a schematic perspective view of the internal combustion engine which has the exhaust gas aftertreatment system which concerns on this invention. It is a figure which showed the detail of the exhaust gas aftertreatment system of FIG. It is a figure which showed III of FIG. 2 in detail. It is a figure which showed IV in place of III of FIG.

The present invention relates to, for example, an exhaust gas aftertreatment system for a stationary internal combustion engine in a power plant or a non-stationary internal combustion engine used in a ship. In particular, the exhaust gas aftertreatment system is used in a marine diesel internal combustion engine that operates on heavy oil.

FIG. 1 shows an arrangement including an internal combustion engine 1 having an exhaust gas supercharging system 2 and an exhaust gas aftertreatment system 3. The internal combustion engine 1 is a non-stationary or stationary internal combustion engine, and may be a marine internal combustion engine that is operated without being particularly stationary. The exhaust gas discharged from the cylinder of the internal combustion engine 1 is used in the exhaust gas supercharging system 2 to obtain mechanical energy for compressing the supercharged air to be supplied to the internal combustion engine 1 from the thermal energy of the exhaust gas. To.

FIG. 1 shows an internal combustion engine 1 having an exhaust gas supercharging system 2. The exhaust gas supercharging system 2 has a plurality of exhaust gas turbochargers, that is, a first high-pressure side exhaust gas turbocharger 4 and a second low-pressure side. Exhaust gas turbocharger 5 and the like are included. The exhaust gas discharged from the cylinder of the internal combustion engine 1 first flows through the high-pressure turbine 6 of the first exhaust gas turbocharger 1, expands in the high-pressure turbine 6, and the energy obtained at that time is the first exhaust gas. It is used to compress the supercharged air in the high-pressure compressor of the turbocharger 4. A second exhaust gas turbocharger 5 is arranged downstream of the first exhaust gas turbocharger 4 when viewed in the direction of exhaust gas flow, and the exhaust gas that has already passed through the high-pressure turbine 6 of the first exhaust gas turbocharger 4 is , Is guided through the second exhaust gas turbocharger 5, that is, through 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 further expands, and the energy obtained at that time is supplied to the cylinder of the internal combustion engine 1 in the low-pressure compressor of the second exhaust gas turbocharger 5. It is used to compress the supercharged air that should be.

In addition to the exhaust gas supercharging system 2 having both 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. Since the SCR exhaust gas aftertreatment system 3 is connected between the high pressure turbine 6 of the first compressor 5 and the low pressure turbine 7 of the second exhaust gas turbocharger 5, the high pressure turbine of the first exhaust gas turbocharger 4 The exhaust gas discharged from 6 can be guided to first pass through the SCR exhaust gas aftertreatment system 3 before reaching the region of the low pressure turbine 7 of the second exhaust gas turbocharger 5.

FIG. 1 shows an exhaust gas supply conduit 8 capable of inducing exhaust gas from the high-pressure turbine 6 of the first exhaust gas turbocharger 4 in the direction of the SCR catalytic converter 9 arranged in the reaction chamber 10.

Further, FIG. 1 shows an exhaust gas discharge conduit 11 used for discharging exhaust gas from the SCR catalytic converter 9 in the direction of the low pressure turbine 7 of the second exhaust gas turbocharger 5.

The exhaust gas flows from the low-pressure turbine 7 to the outside through the conduit 21 as a starting point.

The exhaust gas supply conduit 8 connected to the reaction chamber 10 and thus the SCR catalytic converter 9 arranged in the reaction chamber 10 and the exhaust gas discharge conduit 11 extending from the reaction chamber 10 and therefore the SCR catalytic converter 9 are connected through the bypass 12. It is connected, and the bypass element 12 incorporates a blocking element 13. When the blocking element 13 is closed, the bypass 12 is closed, so that the exhaust gas cannot flow through the bypass. On the other hand, when the blocking element 13 is open, the exhaust gas can flow through the bypass 12 and pass by the reaction chamber 10 and thus the SCR catalytic converter 9 located in the reaction chamber 10. ..

FIG. 2 shows the flow of exhaust gas passing through the exhaust gas aftertreatment system 3 when the bypass 12 is closed by the blocking element 13, with arrow 14, and from FIG. 2, the exhaust gas supply conduit 8 is downstream. It is derived that the side end 15 is open to the reaction chamber 10, and the flow of the exhaust gas is about 180 ° or approximately 180 ° in the region of the end 15 of the exhaust gas supply conduit 8. The exhaust gas is guided to pass through the SCR catalytic converter 9 after the flow direction is changed.

An introduction device 16 is provided in the exhaust gas supply conduit 8 of the exhaust gas aftertreatment system 3, and a reducing agent such as ammonia or an ammonia precursor can be introduced into the flow of exhaust gas through the introduction device 16. The agent is required to selectively convert the nitrogen oxides of the exhaust gas in the region of the SCR catalytic converter 9. The introduction device 16 of the exhaust gas aftertreatment system 3 is preferably an injection nozzle, and ammonia or an ammonia precursor is injected into the flow of exhaust gas in the exhaust gas supply conduit 8 through the injection nozzle. FIG. 2 is a cone 17 that illustrates the injection of the reducing agent into the flow of exhaust gas in the region of the exhaust gas supply conduit 8. The section of the exhaust gas aftertreatment system 3 located downstream of the introduction device 16 and upstream of the SCR catalytic converter 9 in the direction of exhaust gas flow is called a mixing section. In particular, the exhaust gas supply conduit 8 is provided with a mixing section 18 downstream of the introduction device 16, in which the exhaust gas can be mixed with the reducing agent upstream of the SCR catalytic converter 9.

The exhaust gas supply conduit 8 is open to the reaction chamber 10 at the downstream end portion 15. A baffle element 19 is disposed at the downstream end portion 15 of the exhaust gas supply conduit 8, and the baffle element 19 is displaceable with respect to the downstream end portion 15 of the exhaust gas supply conduit 8. In the illustrated embodiment, the baffle element 19 is linearly displaceable with respect to the end 15 of the exhaust gas supply conduit 8 that opens into the reaction chamber 10.

The baffle element 19 is displaceable with respect to the downstream end 15 of the exhaust gas supply conduit 8 so that the exhaust gas supply conduit 8 is blocked at the downstream end 15 or the exhaust gas supply conduit 8 is , Opened at the downstream end 15. Therefore, when the baffle element 19 blocks the exhaust gas supply conduit 8 at the downstream end 15, preferably the blocking element 13 of the bypass 12 is opened, so that the exhaust gas is completely exhausted from the SCR catalytic converter 9. It passes by the side or by the reaction chamber 10 that receives the SCR catalytic converter 9.

If the baffle element 19 opens the downstream end 15 of the exhaust gas supply conduit 8, the blocking element 13 of the bypass 12 may be completely closed or at least partially open. When the baffle element 19 opens the downstream end 15 of the exhaust gas supply conduit 8, the relative position of the baffle element 19 with respect to the downstream end 15 of the exhaust gas supply conduit 8 is particularly the exhaust gas mass flow rate through the exhaust gas supply conduit 8. And / or the exhaust gas temperature in the exhaust gas supply conduit 8 and / or the amount of reducing agent introduced into the exhaust gas flow through the introduction device 16.

A further function of the baffle element 19 when the downstream end 15 of the exhaust gas supply conduit 8 is open is that droplets of liquid reducing agent, which may be present in the flow of exhaust gas, reach the baffle element 19. If so, the purpose is to prevent such droplets of the liquid reducing agent from reaching the region of the SCR catalytic converter 9 by collecting and spraying with the baffle element 19. Through the position of the baffle element 19 relative to the downstream end 15 of the exhaust gas supply conduit 8 when the downstream end 15 is open, especially in the region of the downstream end 15 of the exhaust gas supply conduit 8. The exhaust gas that is redirected in the region 19 is strongly guided or redirected toward the section located radially inside the SCR catalytic converter 9, or is strongly guided toward the section located radially outside. Alternatively, it can be determined whether the direction will be changed.

According to a preferred embodiment, the exhaust gas supply conduit 8 expands in a funnel shape in the region of its downstream end 15 to form a diffuser. As a result, the flow cross section of the exhaust gas supply conduit 8 is enlarged in the region of the downstream end portion 15, and as is particularly clear from FIG. 2, the downstream end portion of the exhaust gas supply conduit 8 is viewed in the direction of the exhaust gas flow. Upstream of 15, it can be specified that its flow cross section first decreases. According to FIG. 2, the flow cross section of the exhaust gas supply conduit 8 is first substantially constant downstream of the reducing agent introduction device 16 when viewed in the direction of exhaust gas flow, then gradually tapering, and finally. In addition, it expands in the region of the downstream end portion 15. At that time, the expansion of the flow cross section at the downstream end portion 15 of the exhaust gas supply conduit 8 is preferably shorter than the portion where the exhaust gas supply conduit 8 is first tapered upstream of the downstream end portion 15. It is carried out over 8 parts.

The baffle element 19 is preferably curved, preferably bell-shaped, on the surface 20 facing the exhaust gas supply conduit 8 to form a flow path for the exhaust gas. The surface 20 of the baffle element 19 facing the downstream end 15 of the exhaust gas supply conduit 8 is radially inside the baffle element 19 with respect to the downstream end 15 of the exhaust gas supply conduit 8. It has a shorter distance than the outer part. Therefore, the baffle element 19 is recessed or curved in the direction of the downstream end portion 15 of the exhaust gas supply conduit 8 at the center of the surface 20 in the direction opposite to the direction in which the exhaust gas flows.

In particular, as can be seen from FIG. 2, the exhaust gas supply conduit 8 and the exhaust gas discharge conduit 11 are connected to or open to the common first surface 22 of the reaction chamber 10, or the common surface 22. Extends into the reaction chamber 10.

At that time, in the exhaust gas supply conduit 8, the downstream end portion 15 of the exhaust gas supply conduit 8 is located adjacent to the second surface 23 of the reaction chamber 10 facing the first surface 22 of the reaction chamber 10. The exhaust gas discharge conduit 11 extends into the reaction chamber 10, whereas the exhaust gas discharge conduit 11 opens into the reaction chamber 10 on the first surface 22. Therefore, the exhaust gas supplied through the exhaust gas supply conduit 8 is turned at an angle of about 180 ° in the region of the second surface 23 of the reaction chamber 10 facing the downstream end 15 of the exhaust gas supply conduit 8. , SCR catalytic converter 9, subsequently through the lower side surface 22, and into the region of the exhaust gas discharge conduit 11. As can be seen from FIG. 2, the exhaust gas discharge conduit 11 then surrounds the exhaust gas supply conduit 8 adjacent to the surface 22 of the reaction chamber 10, partially outward, preferably concentrically.

A reaction that receives an exhaust gas supply conduit 8 and / or an SCR catalytic converter 9 to enable particularly effective exhaust gas post-treatment and particularly effective operation of the internal combustion engine 1 having the exhaust gas after-treatment system 3. The chamber 10 and / or the exhaust gas discharge conduit 11 is configured to have at least a double wall. This ensures that the thermal energy of the exhaust gas remains in the exhaust gas and is not released on a large scale to the walls of the exhaust gas supply conduit 8, the reaction chamber 10, and the exhaust gas discharge conduit 11. The high exhaust gas temperature, on the one hand, is advantageous for effective exhaust gas post-treatment in the region of the SCR catalytic converter 9, and on the other hand, is advantageous for the effective operation of the exhaust gas turbocharger post-installed in the exhaust gas aftertreatment device 3. is there.

The high exhaust gas temperature in the region of the SCR catalytic converter 9 is advantageous to avoid unwanted side reactions of the reducing agent, especially the formation of ammonium sulphate and / or ammonium sulphate. Undesirable by-products that can occur if the flue gas temperature is too low destroys the flue gas supply conduit 8, the SCR catalytic converter 9, the reaction chamber 10, and the flue gas effluent conduit 11, thus impairing the efficiency of flue gas aftertreatment. there is a possibility.

Further, as already described, the high exhaust gas temperature downstream of the exhaust gas aftertreatment device 3 effectively affects the exhaust gas turbocharger arranged downstream of the exhaust gas aftertreatment device 3, especially its low-pressure turbine, when viewed in the flow direction. It is advantageous for driving.

As already mentioned, the exhaust gas supply conduit 8 and / or the reaction chamber 10 and / or the exhaust gas exhaust conduit 11 is configured to have at least a double wall, but also the bypass 12 is at least two. It can be configured to have a heavy wall. In a particularly preferred embodiment of the present invention, the exhaust gas supply conduit 8, the reaction chamber 10, and the exhaust gas discharge conduit 11 are each configured to have at least a double wall. However, only one of these members, in particular the reaction chamber 10, or only two of these members, in particular the exhaust gas supply conduit 8 and the reaction chamber 10, are configured to have at least a double wall. It may have been done.

Further details will be described below with reference to details III and IV of FIGS. 3 and 4. 3 and 4 show alternative and preferred embodiments of the exhaust gas supply conduit 8 and / or the reaction chamber 10 and / or the exhaust gas exhaust conduit 11, respectively, i.e. FIG. 3 shows an embodiment having a double wall. , FIG. 4 shows an aspect having a triple wall.

According to the first advantageous aspect of the present invention, the first wall 24 of the exhaust gas supply conduit 8 and / or the first wall 25 of the reaction chamber 10 and / or the first wall of the exhaust gas discharge conduit 11. 26 is configured such that at the dominant pressure within the exhaust gas supply conduit 8 or the reaction chamber 10 or the exhaust gas discharge conduit 11, each wall 24 or 25 or 26 has a thickness designed to withstand the respective pressures. Has been done. At that time, each pressure is up to 7 bar, preferably at least 2 bar.

At that time, preferably, a second wall 30 or 31 or 32 is arranged on the surface of each of the first walls 24 or 25 or 26 facing the flow of exhaust gas (not shown), and the voids 27 or Forming 28 or 29, the thickness of the second wall is less than the thickness of the respective first wall 24 or 25 or 26. In FIG. 3, the thickness of each first wall 24 or 25 or 26 is indicated by d1, the thickness of each second wall 30 or 31 or 32 is indicated by d2, and each first wall. The dimensions of the voids 27 or 28 or 29 formed between 24 or 25 or 26 and the respective second wall 30 or 31 or 32 are indicated by l12.

According to an advantageous further development of the present invention, the ratio of the thickness d1 of the respective first wall 24 or 25 or 26 to the thickness d2 of the respective second wall 30 or 31 or 32 is at least 10. : 3, preferably at least 10: 2, particularly preferably at least 10: 1. The size l12 of the gap between each first wall 24 or 25 or 26 and each second wall 30 or 31 or 32 is at least 2 mm, preferably at least 4 mm, particularly preferably at least 6 mm. At that time, the product of the mass of the first wall 24 or 25 or 26 and the heat capacity is preferably larger than the product of the corresponding mass of the second wall 30 or 31 or 32 and the heat capacity.

Both the first wall 24 or 25 or 26 and the second wall 30 or 31 or 32 respectively can be formed from a metallic material such as steel. It is preferred that the first wall 24 or 25 or 26 is made of a metallic material and the second wall 30 or 31 or 32 is made of a ceramic material. Similarly, the respective first walls 24, 25, 26 and the respective second walls 30, 31, 32, respectively, may be formed from a metallic material, in which case preferably. Each of the second walls 30, 31, 32 may have a ceramic coating on the surface facing the flow of exhaust gas.

FIG. 4 shows a further development of detail III of FIG. 3 as detail IV, in which there is an additional third wall 33 or 34 or 35, where the third wall is: Arranged on the surface of each first wall 24 or 25 or 26 that faces the flow of exhaust gas, it forms additional voids 36 or 37 or 38. The second walls 30, 31, 32, respectively, located on the surfaces of the first walls 24, 25, 26 facing the flow of the exhaust gas, provide as little thermal energy as possible from the exhaust gas, respectively. Can be guaranteed to be transmitted to the first wall 24 or 25 or 26 of the. The third walls 33, 34, 35, respectively, located on the surfaces of the first walls 24, 25, 26 facing the flow of exhaust gas, release as little thermal energy as possible to the surroundings. Can be guaranteed to be done. In FIG. 4, the thickness of each third wall 33 or 34 or 35 is d3, between the third walls 33, 34, 35 and the first walls 24, 25, 26, respectively. The dimensions of the formed voids 36, 37, 38 are shown by l13.

In particular, the ratio of the thickness of each of the first walls 24, 25, 26 to the thickness of each third wall 33 or 34 or 35 is at least 1: 5, preferably at least 1: 7, particularly preferably. At least 1:10. At that time, the size l13 of the gap preferably matches the size l12 of the gap, and is particularly 2 mm, preferably at least 4 mm, and particularly preferably at least 6 mm. At that time, the product of the mass of the first walls 24, 25, 26 and the heat capacity is preferably smaller than the corresponding product of the mass of the third walls 33, 34, 35 and the heat capacity, respectively. Further, preferably, the ratio of the thermal conductivity of the second wall to the thermal conductivity of the third wall is at least 10: 1, preferably at least 80: 1, and most preferably at least 150: 1.

The voids between the first walls 24, 25, 26 and the third walls 33, 34, 35, respectively, can be omitted. In this case, the respective third wall 33 or 34 or 35 is directly attached to the surface of the respective first walls 24, 25, 26 facing the flow of the exhaust gas. In this case, l13 is 0 mm.

In the internal combustion engine 1 according to FIG. 1, the exhaust gas aftertreatment system 3 stands upright and is arranged above the exhaust gas supercharging system 2. Access to the cylinder of the internal combustion engine 1 is free, but access to the exhaust gas turbochargers 4 and 5 is restricted. However, the reaction chamber 10 can be easily disassembled when maintenance work is required for the exhaust gas turbochargers 4 and 6.

Unlike the case where the exhaust gas aftertreatment system 3 is arranged upright on the upper side of the exhaust gas supercharging system 2 as shown in FIG. 1, the exhaust gas aftertreatment system 3 is rotated by 90 ° to supercharge the exhaust gas. It is possible to arrange the system 2 horizontally, but such a horizontal arrangement increases the length required for the arrangement. However, with respect to the internal combustion engine 1 and the exhaust gas supercharging system 2, maintenance work can be performed without limitation without disassembling the reaction chamber 10.

The method according to the present invention can be used with either a single-stage supercharged engine or a two-stage supercharged engine. In the case of a single-stage supercharged engine, the exhaust gas aftertreatment system is preferably arranged upstream of the turbine, and in the case of a two-stage supercharged engine, it is preferably arranged between two turbines.

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 conduit 9 SCR catalytic converter 10 Reaction chamber 11 Exhaust gas exhaust conduit 12 Bypass 13 Blocking element 14 Exhaust gas Induction 15 End 16 Introducing device 17 Injection cone 18 Mixing section 19 Baffle element 20 Face 21 Conduit 22 Face 23 Face 24 First wall 25 First wall 26 First wall 27 Void 28 Void 29 Void 30 Second wall 31 Second wall 32 Second wall 33 Third wall 34 Third wall 35 Third wall 36 Void 37 Void 38 Void

Claims (16)

The SCR catalytic converter (9), the exhaust gas supply conduit (8) leading to the SCR catalytic converter (9), the exhaust gas discharge conduit (11) extending from the SCR catalytic converter (9), and the exhaust gas supply conduit. An introduction device (16) for introducing a reducing agent such as ammonia or an ammonia precursor, which is arranged in (8), and the exhaust gas are mixed with the reducing agent upstream of the SCR catalytic converter (9). The exhaust gas aftertreatment system (3) of the internal combustion engine having the mixing section (18) supplied downstream of the introduction device (16) by the exhaust gas supply conduit (8), that is, the SCR of the internal combustion engine. In the exhaust gas aftertreatment system
The exhaust gas supply conduit (8) and / or the reaction chamber (10) that receives the SCR catalytic converter (9) and / or the exhaust gas discharge conduit (11) is configured to have at least a double wall. Has been
The first wall (24) of the exhaust gas supply conduit (8) and / or the first wall (25) of the reaction chamber (10) and / or the first wall (11) of the exhaust gas discharge conduit (11). The walls (26) have their respective first walls at a predominant pressure within the exhaust gas supply conduit (8) and / or the reaction chamber (10) and / or the exhaust gas discharge conduit (11). It has a thickness designed to withstand pressure, and the surface of each of the first walls (24, 25, 26) facing the exhaust gas flow has a second wall (30, 31, 26). 32) is arranged, the thickness of the second wall is smaller than the thickness of each of the first walls (24, 25, 26).
A third wall (33, 34, 35) is arranged on the surface of each of the first walls (24, 25, 26) facing the flow of exhaust gas, and the thickness of the third wall. Is greater than the thickness of each of the first walls (24, 25, 26).
An exhaust gas aftertreatment system characterized by this. A gap (27, 28, 29) is formed between the first wall (24, 25, 26) and the second wall (30, 31, 32). The exhaust gas aftertreatment system according to claim 1. The exhaust gas aftertreatment system according to claim 1 or 2 , wherein the ratio of the thickness of each of the first walls to the thickness of each of the second walls is at least 10: 3. The ratio of the thickness of each of the first walls (24, 25, 26) to the thickness of each of the second walls (30, 31, 32) is at least 10: 2. , The exhaust gas aftertreatment system according to claim 3. The ratio of the thickness of each of the first walls (24, 25, 26) to the thickness of each of the second walls (30, 31, 32) is at least 10: 1. , The exhaust gas aftertreatment system according to claim 4. The product of the mass of each of the first walls (24, 25, 26) and the heat capacity is greater than the corresponding product of each of the second walls (30, 31, 32). The exhaust gas aftertreatment system according to any one of claims 1 to 5. The ratio of the thickness of each of the first walls (24, 25, 26) to the thickness of each of the third walls (33, 34, 35) is at least 1: 5. , The exhaust gas aftertreatment system according to claim 1. The ratio of the thickness of each of the first walls (24, 25, 26) to the thickness of each of the third walls (33, 34, 35) is at least 1: 7. , The exhaust gas aftertreatment system according to claim 7. The ratio of the thickness of each of the first walls (24, 25, 26) to the thickness of each of the third walls (33, 34, 35) is at least 1:10. , The exhaust gas aftertreatment system according to claim 8. The product of the mass of each of the first walls (24, 25, 26) and the heat capacity is smaller than the corresponding product of each of the third walls (33, 34, 35). The exhaust gas aftertreatment system according to any one of claims 1 to 9. The thickness of the voids (27, 28, 29) between the first wall (24, 25, 26) and the second wall (30, 31, 32) and / or the first. The thickness of the voids (36, 37, 38) between the walls (24, 25, 26) and the third wall (33, 34, 35) is at least 2 mm, preferably at least 4 mm, particularly preferably. The exhaust gas aftertreatment system according to any one of claims 2 to 10 , wherein the exhaust gas is at least 6 mm. The ratio of the thermal conductivity of the second wall (30, 31, 32) to the thermal conductivity of the third wall (33, 34, 35) is at least 10: 1, preferably at least 80: 1. The exhaust gas aftertreatment system according to any one of claims 1 to 11 , characterized in that the ratio is at least 150: 1. The exhaust gas discharge conduit (11) surrounds the exhaust gas supply conduit (8) adjacent to the reaction chamber (10), partially outward and substantially concentrically, according to claims 1-12. The exhaust gas aftertreatment system according to any one item. An internal combustion engine (1) having the exhaust gas aftertreatment system (3) according to any one of claims 1 to 11, particularly an internal combustion engine (1) operating on diesel fuel or heavy oil fuel. The internal combustion engine is a multi-stage exhaust gas supercharging system (2) including a first exhaust gas turbocharger (4) including a high-pressure turbine (6) and a second exhaust gas turbocharger (5) including a low-pressure turbine (7). The internal combustion engine according to claim 14 , wherein the exhaust gas aftertreatment system (3) is connected between the high-pressure turbine (6) and the low-pressure turbine (7). organ. The internal combustion engine according to claim 14 or 15 , wherein the exhaust gas aftertreatment system (3) is mounted upstream of the exhaust gas turbine.