JP2018003844A - Exhaust gas aftertreatment system and internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new exhaust gas aftertreatment system having a compact configuration and enabling effective exhaust gas aftertreatment and an internal combustion engine having the aftertreatment system.SOLUTION: An exhaust gas aftertreatment system (3) for an internal combustion engine (1) includes: at least one SCR catalyst converter (9) disposed in a reactor chamber (10); an exhaust gas supply line (8) connected to the reactor chamber (10); an exhaust gas release line (11) connected in a direction separating from the reactor chamber (10); an introduction device (12) provided in the exhaust gas supply line (8) to introduce a reducing agent into exhaust gas; and a mixing section (14) disposed downstream of each introduction device (12) to mix the exhaust gas with the reducing agent on the upstream side of the reactor chamber (10). In the exhaust gas aftertreatment system, a compensation element (21) for compensating thermal expansion and separating vibration is incorporated in the exhaust gas supply line (8) in region of the mixing section (14).SELECTED DRAWING: Figure 1

Description

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

  For example, in combustion processes of static internal combustion engines used in power plants and combustion processes of non-static internal combustion engines used, for example, on ships, nitrogen oxides are produced, which are generally It occurs when burning sulfur-containing fossil fuels such as coal, bituminous coal, lignite, petroleum, heavy oil or diesel fuel. An exhaust gas aftertreatment system is therefore provided in this type of internal combustion engine, which is used to purify the exhaust gas leaving the internal combustion engine and in particular to remove nitrogen.

In order to reduce the nitrogen oxides in the exhaust gas, what is known as an SCR catalytic converter is first used in the exhaust gas aftertreatment system. In the SCR catalytic converter, selective catalytic reduction of nitrogen oxide is performed, and in this selective catalytic reduction, ammonia (NH ₃ ) is required to reduce the nitrogen oxide. To this end, ammonia (NH ₃ ) or an ammonia precursor, such as urea, is introduced into the exhaust gas in liquid form upstream of the SCR catalytic converter, and the ammonia or ammonia precursor is mixed with the exhaust gas upstream of the SCR catalytic converter. The To this end, in practice, a mixing section is provided between the introduction of ammonia or ammonia precursor and the SCR catalytic converter.

  Exhaust gas aftertreatment, in particular nitrogen oxide reduction, has already been carried out by an exhaust gas aftertreatment system known from practice with an SCR catalytic converter, but further improvements to the exhaust gas aftertreatment system are required. In particular, it is required to enable effective exhaust gas aftertreatment with a compact configuration.

  Based on this, it is an object of the present invention to create a new exhaust gas aftertreatment system and an internal combustion engine having an aftertreatment system that enables effective exhaust gas aftertreatment in a compact configuration.

  This object is achieved by an exhaust gas aftertreatment system according to claim 1. According to the invention, a compensation element for compensating for thermal expansion and for isolating vibrations is incorporated in the exhaust gas supply line in the region of the mixing section. This enables an effective exhaust gas aftertreatment in an exhaust gas aftertreatment system with a compact configuration.

  The compensation element is preferably constructed as a bellows compensator. The bellows compensator allows a particularly compact configuration of the exhaust gas aftertreatment system.

  According to an advantageous development, the distance from the reducing agent introduction device to the compensation element is at most 7 times, preferably at most 5 times, particularly preferably at most, the diameter of the exhaust gas supply line in the region of the introduction device. 3 times. This development also enables effective exhaust gas aftertreatment in a compactly configured exhaust gas aftertreatment system.

  According to a further advantageous development, the protective element shields the compensation element on the flow side. Preferably, for this purpose, the upstream end of the compensation element is connected to the downstream end of the section of the exhaust gas supply line connected to the compensation element, and the downstream end of the compensation element is connected in a direction away from the compensation element. The exhaust gas supply is connected to the upstream end of the section of the exhaust gas supply line, the compensation element is integrated into the exhaust gas supply line in the region of the mixing section, and the protection element is connected to the compensation element Acts at the downstream end of the section of the line. This development also enables effective exhaust gas aftertreatment in a compactly configured exhaust gas aftertreatment system. In particular, urea decomposition products that impair the function of the compensation element, for example melamine or cyanuric acid, are prevented from being deposited in the region of the compensation element.

  An internal combustion engine according to the invention is defined in claim 8.

  Preferred developments of the invention emerge from the dependent claims and the following description. The exemplary embodiments of the present invention are not limited to the drawings and will be described in more detail based on the drawings.

1 shows a schematic perspective view of an internal combustion engine having an exhaust gas aftertreatment system according to the present invention. 2 shows details of the exhaust gas aftertreatment system of FIG.

  The present invention relates to an exhaust gas aftertreatment system for an internal combustion engine, for example, a stationary internal combustion engine in a power plant or a non-static internal combustion engine used on a ship.

  In particular, the invention relates to an exhaust gas aftertreatment system for a marine diesel internal combustion engine operated using heavy oil, preferably realized as a two-stroke marine diesel internal combustion engine.

  FIG. 1 shows an apparatus composed of an internal combustion engine 1 having an exhaust gas turbocharge system 2 and an exhaust gas aftertreatment system 3. The internal combustion engine 1 is a non-stationary internal combustion engine or a static internal combustion engine, and in particular a marine internal combustion engine that is operated in a non-stationary manner. The exhaust gas exiting the cylinder 4 of the internal combustion engine 1 is used in the exhaust gas charge system 2, thereby obtaining mechanical energy from the thermal energy of the exhaust gas and compressing the charge air supplied by the internal combustion engine 1.

  Thus, FIG. 1 shows an internal combustion engine 1 having an exhaust gas turbocharge system 2 comprising at least one exhaust gas turbocharger 5. The exhaust gas exiting the cylinder 4 of the internal combustion engine 1 flows through the turbine 6 of the exhaust gas turbocharger 5 and is released in the turbine 6, and the energy obtained in the turbine 6 is exhaust gas turbo to compress the charge air. -Used in charger 5 compressor (not shown). The internal combustion engine 1 preferably includes a two-stage exhaust gas turbocharge system 2 having a high pressure turbocharger and a low pressure turbocharger.

  The internal combustion engine 1 includes an exhaust gas aftertreatment system 3 that is an SCR exhaust gas aftertreatment system in addition to the exhaust gas charge system 2. The SCR exhaust gas aftertreatment system 3 is preferably connected between the cylinder 4 of the internal combustion engine 1 and the exhaust gas turbocharge system 2, so that the exhaust gas exiting the cylinder 4 of the internal combustion engine 1 is firstly SCR exhaust gas. Guided through the aftertreatment system 3 and then guided only through the exhaust gas charge system 2.

  FIG. 1 shows an exhaust gas supply line 8, and the exhaust gas starting from the cylinder 4 of the internal combustion engine 1 is guided through the exhaust gas supply line 8 toward an SCR catalytic converter 9 arranged in the reactor chamber 10. Furthermore, FIG. 1 shows an exhaust gas discharge line 11, which is used to discharge exhaust gas from the SCR catalytic converter 9 toward the turbine 6 of the exhaust gas turbocharger 5.

  The internal combustion engine 1 of FIG. 1 has a common exhaust manifold 7 for all cylinders 4. The exhaust gas leaving the cylinder 4 of the internal combustion engine 1 starts from the exhaust gas manifold 7 and travels through the exhaust gas supply line 8 toward the exhaust gas aftertreatment system 3, that is, toward the respective reactor chambers 10 and the respective SCR catalytic converters 9. And is guided downstream of the exhaust gas aftertreatment system 3 via the exhaust gas turbocharger 5 of the exhaust gas turbocharge system 2.

  An exhaust gas supply line 8 connected to the reactor chamber 10 and thus connected to the SCR catalytic converter 9 positioned in the reactor chamber 10 and connected in a direction away from the reactor chamber 10, and thus the SCR catalytic converter 9 or the exhaust manifold. The exhaust gas discharge line 11 connected in a direction away from 7 is preferably connected via a bypass (not shown) incorporating a shut-off valve. When the shutoff valve is closed, the bypass is closed so that no exhaust gas can flow through the bypass. Conversely, when the shutoff valve is open, the exhaust gas can flow through the bypass, specifically, can flow directly from the exhaust gas supply line 8 into the exhaust gas discharge line 11, and the reactor chamber 10. And the SCR catalytic converter 9 positioned in the reactor chamber.

  An introduction device 12 is provided in the exhaust gas supply line 8 of the exhaust gas aftertreatment system 3 and a reducing agent, in particular ammonia or an ammonia precursor, can be introduced into the exhaust gas stream by this introduction device, which is an SCR catalyst. It is required to convert the nitrogen oxides of the exhaust gas in the manner prescribed in the converter 9 area.

  This introduction device 12 of the exhaust gas aftertreatment system 3 is preferably an injection nozzle, and ammonia or an ammonia precursor, for example urea or an aqueous urea solution, is injected into the exhaust gas flow inside the exhaust gas supply line 8 by the injection nozzle. FIG. 2 uses a cone 13 to clarify the injection of the reducing agent into the exhaust gas stream in the region of the exhaust gas supply line 8.

  The section of the exhaust gas aftertreatment system 3 located downstream of the introduction device 12 and upstream of the SCR catalytic converter 9 in the flow direction is referred to as the mixing section 14. In particular, the exhaust gas supply line 8 provides a mixing section 14 downstream of the introduction device 12 in which the exhaust gas can be mixed with the reducing agent upstream of the SCR catalytic converter 9.

  The exhaust gas manifold 7 and the mixing section 14 of the internal combustion engine 1 are preferably combined with the exhaust gas supply line 8 to form a common assembly. In this case, according to a preferred embodiment, the exhaust gas supply line 8 forming the mixing section 14 in at least certain sections is positioned coaxially after the exhaust gas manifold 7 when viewed in the flow direction of the exhaust gas.

  According to FIG. 1, each assembly of the internal combustion engine 1, which forms the exhaust manifold 7, the mixing section 14 and the exhaust gas supply line 8, allows the exhaust gas coming out of the respective exhaust manifold 7 to change direction. Constructed in such a way that it can be fed to each mixing section 14 in a manner that is not. Accordingly, in FIG. 1, when the exhaust gas enters the exhaust gas manifold 7 in the region of the cylinder side exhaust gas orifice 16 and when it enters the reactor chamber 10 in the region of the downstream end 15 of the exhaust gas supply line 8 upstream of the SCR catalytic converter 9. And only experience a change of direction. This is advantageous in order to ensure effective exhaust gas aftertreatment in a compact configuration.

  1 and 2, the flow of exhaust gas is clarified by arrows 17. It can be seen from FIG. 1 that the exhaust gas 17 is diverted approximately 90 ° or close to 90 ° in the region of the cylinder side exhaust gas orifice 16 and flows into the exhaust gas manifold 7. The exhaust gas starts from the exhaust gas manifold 7 and flows through the exhaust gas supply line 8 in a non-directional manner to the downstream end 15 of the exhaust gas supply line 8, and the downstream end 15 opens in the region of the reactor chamber 10. Yes. In the region of this end 15 of the exhaust gas supply line 8, the exhaust gas experiences a flow diversion of approximately 180 ° or nearly 180 °, and the exhaust gas is guided through the SCR catalytic converter 9 after this flow diversion. The

  The exhaust gas supply line 8 is open into the reactor chamber 10 at the downstream end 15. According to a preferred embodiment, the exhaust gas supply line 8 is widened in a funnel shape in the region of the downstream end 15 of the exhaust gas supply line 8, thereby forming a diffuser 18. As a result, the flow cross section of the exhaust gas supply line 8 is enlarged in the region of the downstream end 15, and when viewed in the flow direction of the exhaust gas, the exhaust gas supply line 8 upstream of the diffuser 18 at the downstream end 15 of the exhaust gas supply line 8. It is provided that the flow cross section is first reduced.

  The exhaust gas supply line 8 and the exhaust gas discharge line 11 act on a common first side 19 of the reactor chamber 10. In this case, the exhaust gas supply line 8 starting from this first side 19 is such that the downstream end 15 of the exhaust gas supply line 8 is the second side 20 of the reactor chamber opposite the first side 19 of the reactor chamber 10. Extends into the reactor chamber 10 so as to be positioned next to each other. The exhaust gas discharge line 11 is open into the reactor chamber 10 on the first side 19. The exhaust gas supplied through the exhaust gas supply line 8 is redirected in the region on the second side 20 of the reactor chamber 10 facing the downstream end 15 of the exhaust gas supply line 8 and then through the SCR catalytic converter 9. And flows into the region of the exhaust gas discharge line 11 via the first side 19. The exhaust gas discharge line 11 surrounds the exhaust gas supply line 8 adjacent to the first side 19 of the reactor chamber 10 from the outside, preferably concentrically, in a given section.

  A compensation element 21 is incorporated in the exhaust gas supply line 8 in the region of the mixing section 14, ie downstream of the introduction device 12 for the reducing agent and upstream of the reactor chamber 10 and thus upstream of the SCR catalytic converter 9, This compensation element is used to compensate for thermal expansion and to isolate vibrations.

  Thermal expansion in the region of the exhaust gas supply line 8 that may occur during operation of the exhaust gas aftertreatment system 3 by the operating internal combustion engine 1 and the exhaust gas charging system 2 in which the internal combustion engine 1 is operating, and exhaust gas Vibrations in the region of the supply line 8 can be compensated.

  By incorporating such a compensation element 21 into the exhaust gas supply line 8 in the region of the mixing section 14, an effective exhaust gas aftertreatment is an exhaust gas aftertreatment system with a compact configuration, and finally an internal combustion engine with a compact configuration. Can be guaranteed by the institution

  The compensation element 21 is preferably a bellows compensator.

  The upstream end 21 a of the compensation element 21 acts on the downstream end 22 of the section 8 a of the exhaust gas supply line 8, which is connected to the compensation element 21, while the downstream end 21 b of the compensation element 21 extends from the compensation element 21. The compensation element 21 is integrated into the exhaust gas supply line 8 in the region of the mixing section 14 so as to act on the upstream end 23 of the section 8b of the exhaust gas supply line 8 which is connected in the direction away from it.

  The distance from the introduction device 12 for the reducing agent to the compensation element 21 is connected to the diameter of the exhaust gas supply line 8 in the region of the introduction device 12, i.e. in the region of the introduction device 12 for the reducing agent. The diameter of the section 8a of the exhaust gas supply line 8 corresponds to at most 7 times, preferably at most 5 times, particularly preferably at most 3 times. This is particularly preferred in order to optimally compensate for thermal expansion and to isolate vibrations optimally in a compact configuration while ensuring effective exhaust gas aftertreatment.

  At this stage, in particular when the reactor chamber 10, and thus the SCR catalytic converter 9, is arranged upstream of the exhaust gas turbocharger 5 as shown in the exemplary embodiment, the compensation element 21 has a particularly increased pressure. It is pointed out that the shear force is additionally compensated in order to compensate for the gas force caused by the.

  According to one development, it is provided that the compensation element 21 incorporated in the exhaust gas supply line 8 is covered by the protective element 24 from the exhaust gas stream. The protective element 24 in this case acts on the section 8a of the exhaust gas supply line 8 connected to the compensation element 21 and starts from this section 8a of the exhaust gas supply line 8 when viewed in the through-flow direction, ie the exhaust gas supply line 8 Starting from the downstream end 22 of this section 8a, it extends towards the section 8b of the exhaust gas supply line 8 leading away from the compensation element 21, where it covers the compensation element 21 from the exhaust gas flow. On the inflow side of the compensation element 21, the compensation element 21 is completely covered by a protective element 24 which is closed there. On the outflow side of the compensation element 21, the compensation element 21 is accessible by a protection element 24 which is open there. The unrestricted function of the compensation element 21 to compensate for thermal expansion and to isolate vibrations is ensured by the protective element 24, while the reductive decomposition products are deposited on the compensation element 21 and It is prevented that the function of the compensation element 21 is impaired.

  As described above, effective exhaust aftertreatment of the exhaust gas leaving the cylinder 4 of the internal combustion engine 1 is ensured by the compensation element 21 in a particularly compact configuration.

  In the exemplary embodiment of FIG. 1, a common assembly providing an exhaust manifold 7, a mixing section 14, an exhaust gas supply line 8, and a compensation element 21 additionally incorporated in the exhaust gas supply line 8 is provided. It is realized that the exhaust gas coming in is supplied to the exhaust manifold 7 of each mixing section 14 in a non-reversing manner. This is preferred as described above. Conversely, an exemplary embodiment is also possible in which the exhaust gas experiences a simple diversion starting from the exhaust gas manifold 7 into the region of the mixing section 14 and thus into the region of the exhaust gas supply line 8; That is, the exhaust gas is redirected once, specifically to a maximum of 90 ° during movement from the exhaust gas manifold 7 into the exhaust gas supply line 8 and subsequently into the region of the mixing section 14. For reasons of installation space in the internal combustion engine, if a large number of diversions of the exhaust gas should be required, the exhaust gas coming out of the exhaust gas manifold 7 will have a maximum of 3 diversions or a maximum of 270 ° of the exhaust gas. Preferably, the exhaust gas is redirected between the exhaust manifold 7 and the mixing section 14 and fed to the mixing section 14, preferably with a maximum of two reorientations of the exhaust gas or mixing with the exhaust manifold 7 at a maximum of 180 °. An assembly is constructed that provides the exhaust manifold 7, the exhaust gas supply line 8, the mixing section 14, and the compensation element 21 so that the exhaust gas is redirected to and fed to the mixing section 14. Is provided in the sense of the present invention. A direction change of the exhaust gas between the exhaust manifold 7 and the mixing section 14 of at most 90 ° is preferred, but a feed without a redirection of the exhaust gas starting from the exhaust manifold 7 towards the mixing section 14 is preferred. These details also provide effective exhaust aftertreatment in a compact configuration.

  The distance between the cylinder side exhaust orifice 16 into the respective exhaust manifold 7 and the SCR catalytic converter 9 or the reactor chamber 10 that is positioned farthest from the SCR catalytic converter 9 or the respective reactor 10 is the SCR catalytic converter. 9 or the cylinder side exhaust orifice 16 into the exhaust manifold 7 located farthest from the reactor chamber 10 and the cylinder side exhaust orifice into the exhaust manifold 7 located closest to the SCR catalytic converter 9 or reactor chamber 10 16, the exhaust manifold 7, the mixing section 14, the compensation element 21, and the exhaust gas supply line 8 so as to correspond to at most 6 times, preferably at most 4 times, particularly preferably at most 2 times the distance between The common assembly that forms Mashiku is constructed. This is also advantageous in order to ensure effective operation and effective exhaust gas aftertreatment of the internal combustion engine with a compact configuration and to keep the length of the compensation element to a minimum.

  In the exemplary embodiment shown, the reactor chamber 10, and thus the SCR catalytic converter 9, is arranged on the exhaust gas side upstream of the exhaust gas turbocharger 5. The reactor chamber 10 and thus the SCR catalytic converter 9 can also be arranged on the exhaust gas side downstream of the exhaust gas turbocharger. The reactor chamber 10, and thus the SCR catalytic converter 9, can further be connected to the exhaust gas side between the high pressure exhaust gas turbocharger and the low pressure exhaust gas turbocharger.

  The details described above are particularly suitable for use with two-stroke internal combustion engines, which are operated using residual oil or with heavy oil or with natural gas. However, the present invention can also be used in a four-stroke internal combustion engine.

1 internal combustion engine, 2 exhaust gas charge system, 3 exhaust gas aftertreatment system, 4 cylinder, 5 exhaust gas turbocharger, 6 turbine, 7 exhaust gas manifold, 8 exhaust gas supply line, 8a section, 8b, section, 9 SCR catalytic converter, 10 reactor chamber 11 exhaust gas discharge line, 12 inlet device, 13 injection cone, 14 mixing section, 15 end, 16 exhaust orifice, 17 flow, 18 diffuser, 19 side, 20 side, 21 compensation element, 21a end, 21b end, 22 end, 23 end, 24 protective element

Claims (12)

An exhaust gas aftertreatment system (3) for an internal combustion engine (1),
At least one SCR catalytic converter (9) disposed in the reactor chamber (10), an exhaust gas supply line (8) connected to the reactor chamber (10), and a direction away from the reactor chamber (10) An exhaust gas discharge line (11), an introduction device (12) provided in the exhaust gas supply line (8) for introducing a reducing agent into the exhaust gas, and the exhaust gas upstream of the reactor chamber (10). An exhaust gas aftertreatment system comprising a mixing section (14) arranged downstream of each introduction device (12) for mixing with the reducing agent;
An exhaust gas aftertreatment system, characterized in that a compensation element (21) for compensating for thermal expansion and for isolating vibrations is incorporated in the exhaust gas supply line (8) in the region of the mixing section (14). .   The exhaust gas aftertreatment system according to claim 1, characterized in that the compensation element (21) is constructed as a bellows compensator.   The distance from the introduction device (12) to the compensation element (21) corresponds to at most 7 times the diameter of the exhaust gas supply line (8) in the region of the introduction device (12). The exhaust gas aftertreatment system according to claim 1 or 2.   The distance from the introduction device (12) to the compensation element (21) corresponds to at most 5 times the diameter of the exhaust gas supply line (8) in the region of the introduction device (12). The exhaust gas after-treatment system according to claim 3.   The distance from the introduction device (12) to the compensation element (21) corresponds to at most three times the diameter of the exhaust gas supply line (8) in the region of the introduction device (12). An exhaust gas aftertreatment system according to claim 4.   6. The exhaust gas aftertreatment system according to claim 1, wherein a protective element (24) shields the compensating element (21) on the flow side. The upstream end (21a) of the compensation element (21) is connected to the downstream end (22) of the section (8a) of the exhaust gas supply line (8) connected to the compensation element (21). And the upstream end (23b) of the section (8b) of the exhaust gas supply line (8), wherein the downstream end (21b) of the compensation element (21) is connected in a direction away from the compensation element (21). The compensation element (21) is integrated into the exhaust gas supply line (8) in the region of the mixing section (14),
The protective element (24) acts at the downstream end (22) of the section (8a) of the exhaust gas supply line (8) connected to the compensation element (21) and on the flow side the compensation element The exhaust gas aftertreatment system according to any one of claims 1 to 6, wherein (21) is shielded. The exhaust gas aftertreatment system (3) according to any one of claims 1 to 7, and a plurality of cylinders (4), at least one exhaust gas manifold (7) common to a group of cylinders (4), An internal combustion engine (1) comprising:
The exhaust gas coming out of each exhaust gas manifold (7) can be guided through the exhaust gas aftertreatment system (3) and downstream of the exhaust gas aftertreatment system (3) the internal combustion engine (1) An internal combustion engine, characterized in that it can be guided via at least one exhaust gas turbocharger (5) of the exhaust gas charging system (2).   9. Each exhaust gas manifold (7), each said mixing section (14) and each said compensation element (21) are combined to form a common assembly. Internal combustion engine.   A cylinder side exhaust orifice (16) into the exhaust manifold (7), located farthest from the respective SCR catalytic converter (9) or the respective reactor chamber (10), and the respective SCR catalytic converter (9 ) Or the respective reactor chambers (10), the respective exhaust manifolds (7) located at the furthest distance from the respective SCR catalytic converters (9) or the respective reactor chambers (10). The cylinder-side exhaust orifices (16) into the cylinders into the exhaust manifolds (7) located closest to the respective SCR catalytic converter (9) or the respective reactor chamber (10) Side exhaust gas orifice (16) 10. Internal combustion engine according to claim 9, characterized in that each said common assembly is constructed so as to correspond to at most 6 times, preferably at most 4 times, particularly preferably at most 2 times. .   The exhaust gas coming out of each exhaust gas manifold (7) has a maximum of 3 turns, preferably at most 2 turns, particularly preferably at most 1 turn. 11. An internal combustion engine according to any one of claims 8 to 10, characterized in that it can be supplied to the mixing section (14).   The exhaust gas coming out of each exhaust gas manifold (7) has a direction change of at most 270 °, preferably at most 180 °, particularly preferably at most 90 °. 12. Internal combustion engine according to any one of claims 8 to 11, characterized in that it can be supplied to the mixing section (17).