JP7091029B2 - 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 and an internal combustion engine having the exhaust gas aftertreatment system.

For example, in the combustion process of a static internal combustion engine used in a power plant and, for example, the combustion process of a non-static internal combustion engine used on a ship, nitrogen oxides are produced, and these nitrogen oxides are generally produced. It occurs when burning sulfur-containing fossil fuels such as coal, bituminous coal, brown coal, petroleum, heavy oil or diesel fuel. Therefore, an exhaust gas aftertreatment system is provided in this type of internal combustion engine, and these exhaust gas aftertreatment systems are used to purify the exhaust gas emitted from the internal combustion engine, particularly to remove nitrogen.

In order to reduce nitrogen oxides in exhaust gas, known SCR catalytic converters are first used in exhaust gas aftertreatment systems. In the SCR catalytic converter, selective catalytic reduction of nitrogen oxides is performed, in which ammonia (NH ₃ ) is required to reduce the nitrogen oxides. Ammonia (NH ₃ ) or an ammonia precursor, such as urea, is therefore 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. To. 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 post-treatment, particularly nitrogen oxide reduction, has already been carried out by an exhaust gas after-treatment system known from practice, which comprises an SCR catalytic converter, but there is a demand for further improvement of the exhaust gas after-treatment system. In particular, it is required to enable effective exhaust gas aftertreatment with a compact configuration.

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

This object is achieved by the exhaust gas aftertreatment system according to claim 1. According to the present invention, a compensating element for compensating for thermal expansion and for separating vibration is incorporated in the exhaust gas supply line in the region of the mixing section. This enables effective exhaust gas aftertreatment in a compactly configured exhaust gas aftertreatment system.

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

According to favorable developments, the distance from the reducing agent introduction device to the compensating element is up to 7 times, preferably at most 5 times, particularly preferably at most the diameter of the exhaust gas supply line in the area of the introduction device. It is three times. This development also enables effective exhaust gas aftertreatment in a compactly configured exhaust gas aftertreatment system.

According to further favorable developments, the protective element shields the compensating element on the flow side. Preferably, for this purpose, the upstream end of the compensating element is connected to the downstream end of the section of the exhaust gas supply line, which is connected to the compensating element, and the downstream end of the compensating element is connected in a direction away from the compensating element. The compensating element is incorporated into the exhaust gas supply line in the area of the mixing section so that it is connected to the upstream end of the section of the exhaust gas supply line, and the protective element is connected to the compensating element, the exhaust gas supply. It 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 compensating element, such as melamine or cyanuric acid, are prevented from depositing in the area of the compensating element.

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

Preferred developments of the present invention will be apparent from the dependent claims and the following description. Exemplary embodiments of the present invention are not limited to the drawings, but will be described in more detail with reference to the drawings.

A schematic perspective view of an internal combustion engine having an exhaust gas aftertreatment system according to the present invention is shown. The details of the exhaust gas aftertreatment system of FIG. 1 are shown.

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

In particular, the present 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-static internal combustion engine or a static internal combustion engine, and is particularly a marine internal combustion engine operated in a non-static system. The exhaust gas discharged from 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.

As described above, FIG. 1 shows an internal combustion engine 1 having an exhaust gas turbocharge system 2 including at least one exhaust gas turbocharger 5. The exhaust gas discharged from 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 by the turbine 6 is exhaust gas turbo to compress the charge air. -Used in the compressor of charger 5 (not shown). Preferably, the internal combustion engine 1 comprises 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 which 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. Therefore, the exhaust gas exiting the cylinder 4 of the internal combustion engine 1 is first the SCR exhaust gas. It is guided via the post-treatment system 3 and then 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 to the SCR catalytic converter 9 arranged in the reactor chamber 10 via the exhaust gas supply line 8. Further, 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 gas manifold 7 for all cylinders 4. The exhaust gas exiting the cylinder 4 of the internal combustion engine 1 starts from the exhaust gas manifold 7 and heads toward the exhaust gas aftertreatment system 3 via the exhaust gas supply line 8, that is, toward each reactor chamber 10 and each SCR catalytic converter 9. And, it is guided downstream of the exhaust gas aftertreatment system 3 via the exhaust gas turbocharger 5 of the exhaust gas turbocharge system 2.

The 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 the exhaust gas supply line 8 connected away from the reactor chamber 10, thus the SCR catalytic converter 9 or the exhaust gas manifold. The exhaust gas discharge line 11 connected in the direction away from 7 is preferably connected via a bypass (not shown) incorporating a shut-off valve. When the shut-off valve is closed, the bypass is closed so that exhaust gas cannot flow through the bypass. Conversely, when the shut-off valve is open, the exhaust gas can flow through the bypass, specifically, directly from the exhaust gas supply line 8 into the exhaust gas discharge line 11 and in the reactor chamber 10. And the SCR catalytic converter 9 positioned in the reactor chamber.

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

The 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 by the injection nozzle into the exhaust gas flow inside the exhaust gas supply line 8. FIG. 2 uses a cone 13 to clarify the injection of the reducing agent into the exhaust gas flow 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 when viewed in the flow direction is referred to as a 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 together 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 at least in a predetermined section is coaxially positioned after the exhaust gas manifold 7 when viewed in the flow direction of the exhaust gas.

According to FIG. 1, in each assembly of the internal combustion engine 1 forming the exhaust gas manifold 7, the mixing section 14, and the exhaust gas supply line 8, the exhaust gas emitted from the respective exhaust gas manifold 7 changes direction. It is constructed so that it can be supplied to each mixing section 14 in a non-method. Therefore, in FIG. 1, when the exhaust gas enters the exhaust gas manifold 7 in the region of the exhaust gas orifice 16 on the cylinder side 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 to ensure effective exhaust gas aftertreatment in a compact configuration.

In FIGS. 1 and 2, the flow of exhaust gas is clarified by the arrow 17. From FIG. 1, it can be seen that the exhaust gas 17 is turned around 90 ° or nearly 90 ° in the region of the cylinder side exhaust gas orifice 16 and flows into the exhaust gas manifold 7. Exhaust gas starts from the exhaust gas manifold 7 and flows through the exhaust gas supply line 8 in a non-turning manner to the downstream end 15 of the exhaust gas supply line 8, where the downstream end 15 opens in the region of the reactor chamber 10. There is. 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 via the SCR catalytic converter 9 after this flow diversion. To.

The exhaust gas supply line 8 is open in the reactor chamber 10 at the downstream end 15. According to a preferred embodiment, the exhaust gas supply line 8 is widened to form a funnel in the region of the downstream end 15 of the exhaust gas supply line 8, thereby forming the diffuser 18. As a result, the flow cross section of the exhaust gas supply line 8 is expanded in the region of the downstream end portion 15, and when viewed in the flow direction of the exhaust gas, the exhaust gas supply line 8 is upstream of the diffuser 18 at the downstream end portion 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 the common first side 19 of the reactor chamber 10. In this case, in the exhaust gas supply line 8 starting from the first side 19, the downstream end portion 15 of the exhaust gas supply line 8 is the second side 20 of the reactor chamber on the opposite side of the first side 19 of the reactor chamber 10. Extends within the reactor chamber 10 so that it is positioned adjacent to. The exhaust gas discharge line 11 is open in the reactor chamber 10 on the first side 19. The exhaust gas supplied through the exhaust gas supply line 8 is turned around in the region of the second side 20 of the reactor chamber 10 facing the downstream end 15 of the exhaust gas supply line 8 and then via the SCR catalytic converter 9. And then flow 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 predetermined section.

The compensating element 21 is incorporated into 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 compensating element is used to compensate for thermal expansion and to separate vibrations.

Thermal expansion in the region of the exhaust gas supply line 8 and exhaust gas that may occur during the operation of the exhaust gas aftertreatment system 3 due to the operating internal combustion engine 1 and the operating exhaust gas charging system 2 of the internal combustion engine 1. Vibration in the region of the supply line 8 can be compensated for.

By incorporating such a compensating element 21 into the exhaust gas supply line 8 in the region of the mixing section 14, effective exhaust gas aftertreatment is a compactly configured exhaust gas aftertreatment system and thus ultimately a compactly configured internal combustion engine. It can be guaranteed by the institution.

The compensating element 21 is preferably a bellows-shaped compensator.

The upstream end 21a of the compensating element 21 acts on the downstream end 22 of the section 8a of the exhaust gas supply line 8 connected to the compensating element 21, while the downstream end 21b of the compensating element 21 is from the compensating element 21. The compensating element 21 is incorporated 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 distant direction.

The distance from the introduction device 12 for the reducing agent to the compensating element 21 is connected to the compensating element 21 in the diameter of the exhaust gas supply line 8 in the region of the introducing device 12, i.e., in the region of the introducing device 12 for the reducing agent. It corresponds to a maximum of 7 times, preferably a maximum of 5 times, and particularly preferably a maximum of 3 times the diameter of the section 8a of the exhaust gas supply line 8. This is particularly preferred for optimally compensating for thermal expansion and optimally separating vibrations in a compact configuration while ensuring effective exhaust gas post-treatment.

At this stage, the compensating element 21 is particularly increased in pressure, especially if the reactor chamber 10, and thus the SCR catalytic converter 9, is located upstream of the exhaust gas turbocharger 5, as shown in an exemplary embodiment. It is pointed out that the shear force is additionally compensated in order to compensate the gas force generated due to the above.

According to some developments, the compensating element 21 incorporated in the exhaust gas supply line 8 is provided to be covered from the exhaust gas flow by the protective element 24. 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 flow direction, that is, the exhaust gas supply line 8. Starting from the downstream end 22 of section 8a of the above, extending toward section 8b of the exhaust gas supply line 8 connected in a direction away from the compensation element 21, where the exhaust gas flow covers the compensation element 21. On the inflow side of the compensating element 21, the compensating element 21 is completely covered by the protective element 24 closed there. On the outflow side of the compensating element 21, the compensating element 21 is accessible by the protective element 24 open there. The unrestricted function of the compensating element 21 to compensate for thermal expansion and to separate vibrations is guaranteed by the protective element 24, while the reduction decomposition product is deposited on the compensating element 21 and It is prevented from impairing the function of the compensation element 21.

As described above, the effective exhaust gas post-treatment of the exhaust gas emitted from the cylinder 4 of the internal combustion engine 1 is guaranteed by the compensating element 21 in a particularly compact configuration.

In an exemplary embodiment of FIG. 1, a common assembly is provided that provides an exhaust gas manifold 7, a mixing section 14, an exhaust gas supply line 8, and an additional compensating element 21 incorporated into the exhaust gas supply line 8. It is realized so that the incoming exhaust gas is supplied to the exhaust gas manifold 7 of each mixing section 14 in a non-turning manner. This is preferable as described above. Conversely, exemplary embodiments are also possible in which the exhaust gas experiences a simple turn in which the exhaust gas flow departs 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 specifically turned once, up to 90 °, while moving from the exhaust gas manifold 7 into the exhaust gas supply line 8 and subsequently into the region of the mixing section 14. If a large number of exhaust gas diversions should be required due to the installation space in the internal combustion engine, the exhaust gas coming out of the exhaust gas manifold 7 can be diverted up to 3 times or up to 270 °. The exhaust gas is preferably redirected up to twice or mixed with the exhaust gas manifold 7 at a maximum of 180 ° so that the exhaust gas is redirected between the exhaust gas manifold 7 and the mixing section 14 and supplied to the mixing section 14. An assembly is constructed that provides the exhaust gas manifold 7, the exhaust gas supply line 8, the mixing section 14, and the compensating element 21 so that the exhaust gas is redirected between sections 14 and supplied to the mixing section 14. That is provided in the sense of the present invention. A turning of the exhaust gas between the exhaust gas manifold 7 and the mixing section 14 at a maximum of 90 ° is preferred, but a non-turning supply of the exhaust gas starting from the exhaust gas manifold 7 towards the mixing section 14 is preferred. These details also provide effective exhaust gas post-treatment in a compact configuration.

The distance between the cylinder-side exhaust gas orifice 16 into each exhaust gas manifold 7 located farthest from the SCR catalytic converter 9 or each reactor 10 and the SCR catalytic converter 9 or the reactor chamber 10 is the SCR catalytic converter. The cylinder-side exhaust gas orifice 16 into the exhaust gas manifold 7 located farthest from the 9 or the reactor chamber 10 and the cylinder-side exhaust gas orifice into the exhaust gas manifold 7 located closest to the SCR catalytic converter 9 or the reactor chamber 10. The exhaust gas manifold 7, the mixing section 14, the compensating element 21, and the exhaust gas supply line 8 correspond to a maximum of 6 times, preferably a maximum of 4 times, particularly preferably a maximum of 2 times the distance between 16. A common assembly forming and is preferably constructed. This is advantageous to ensure the effective operation of the internal combustion engine and the effective exhaust gas post-treatment due to the compact configuration, and also to keep the length of the compensating element to a minimum.

In the exemplary embodiment shown, the reactor chamber 10, and thus the SCR catalytic converter 9, is located upstream of the exhaust gas turbocharger 5 on the exhaust gas side. The reactor chamber 10, and thus the SCR catalytic converter 9, can also be located on the exhaust gas side downstream of the exhaust gas turbocharger. It is further possible that the reactor chamber 10, and thus the SCR catalytic converter 9, 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 in two-stroke internal combustion engines, which are operated with residual oil or with heavy oil or with natural gas. However, the present invention can also be used in a 4-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 emission line, 12 introduction device, 13 injection cone, 14 mixing section, 15 end, 16 exhaust gas orifice, 17 flow, 18 diffuser, 19 side, 20 side, 21 compensating element, 21a end, 21b end, 22 ends, 23 ends, 24 protective elements

Claims (9)

An exhaust gas aftertreatment system (3) for an internal combustion engine (1).
At least one SCR catalytic converter (9) arranged 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). The exhaust gas is discharged upstream of the exhaust gas discharge line (11), the introduction device (12) provided in the exhaust gas supply line (8) for introducing the reducing agent into the exhaust gas, and the reactor chamber (10). In an exhaust gas aftertreatment system having a mixing section (14) located downstream of each introduction device (12) for mixing with the reducing agent.
A compensating element (21) for compensating for thermal expansion and separating vibration is incorporated in the exhaust gas supply line (8) in the region of the mixing section (14).
The compensation element (21) is located inside the outer surface of the exhaust gas supply line (8).
The protective element (24) shields the compensation element (21) on the flow side, and the protective element (24) is located inside the exhaust gas supply line (8) from the inner wall of the exhaust gas supply line (8). It is characterized by having a portion extending toward the direction and a portion extending from the portion in the flow direction of the exhaust gas so as not to protrude from the compensation element (21) in the flow direction of the exhaust gas. Exhaust gas aftertreatment system. The exhaust gas aftertreatment system according to claim 1, wherein the compensating element (21) is constructed as a bellows-shaped compensator. The feature is that the distance from the introduction device (12) to the compensation element (21) corresponds to a maximum of 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 upstream end (21a) of the compensating element (21) is connected to the downstream end (22) of the section (8a) of the exhaust gas supply line (8) connected to the compensating element (21). In addition, the downstream end (21b) of the compensating element (21) is connected to the compensating element (21) in a direction away from the upstream end (23) of the section (8b) of the exhaust gas supply line (8). ), The compensating element (21) is incorporated 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), which is connected to the compensating element (21), and the compensating element on the flow side. The exhaust gas aftertreatment system according to any one of claims 1 to 3, wherein (21) is shielded. A plurality of cylinders (4), at least one exhaust gas manifold (7) common to a group of cylinders (4), and the exhaust gas aftertreatment system (3) according to any one of claims 1 to 4 . An internal combustion engine (1) having a
The exhaust gas emitted from each of the exhaust gas manifolds (7) can be guided via the exhaust gas aftertreatment system (3), and the internal combustion engine (1) is downstream of the exhaust gas aftertreatment system (3). An internal combustion engine characterized in that it can be guided via at least one exhaust gas turbocharger (5) of the exhaust gas charge system (2). 5. The fifth aspect of the present invention, wherein each of the exhaust gas manifolds (7), each of the mixed sections (14), and each of the compensating elements (21) are combined to form a common assembly. Internal combustion engine. A first cylinder-side exhaust gas orifice (16) into the exhaust gas manifold (7), located farthest from each said SCR catalytic converter (9) or each reactor chamber (10), and each said SCR catalyst. The distance between the converter (9) or each reactor chamber (10) is the first cylinder-side exhaust gas orifice (16) into each said exhaust gas manifold (7) and the respective said SCR catalytic converter. At most, the distance between (9) or the second cylinder-side exhaust gas orifice (16) into each said exhaust gas manifold (7), located closest to each said reactor chamber (10). The internal combustion engine according to claim 6 , wherein each of the common assemblies is constructed so as to correspond to 6 times. Any of claims 5 to 7 , wherein the exhaust gas emitted from each of the exhaust gas manifolds (7) can be supplied to each of the mixed sections (14) with a maximum of three turns. The internal combustion engine described in the first paragraph. Any of claims 5 to 8 , wherein the exhaust gas emitted from each of the exhaust gas manifolds (7) can be supplied to each of the mixed sections (17) with a maximum turn of 270 °. The internal combustion engine described in the first paragraph.

Images