Exhaust gas aftertreatment device

Abstract

To provide an exhaust gas aftertreatment device for an internal combustion engine, an internal combustion engine, and a method for exhaust gas aftertreatment.SOLUTION: The exhaust gas aftertreatment device comprises an elongated exhaust manifold with a plurality of inlet ports and a catalyst container. The exhaust manifold and the catalyst container are arranged side by side next to one another and are delimited from one another by at least one partition wall extending along a longitudinal direction. The exhaust gas manifold is fluidly connected with the catalyst container over at least one passage, which is provided in the partition wall, to guide exhaust gas into the catalyst container. At least one reductant supply element, e.g., an urea injector, is arranged in the exhaust manifold within or near at least one inlet port. At least one flow guiding element is arranged in the exhaust manifold for guiding exhaust gas toward the passage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas aftertreatment device for an internal combustion engine, an internal combustion engine, and a method of exhaust gas aftertreatment.

[0002] The present invention relates to an internal combustion engine, preferably a marine or ship engine, or a stationary engine having a cylinder with an internal diameter of at least 200 mm. The engine is preferably a two-stroke engine or a two-stroke crosshead engine. The engine may be a diesel or gas engine, and may be a dual-fuel or multi-fuel engine. The combustion of liquid and / or gas fuels in such engines may be either auto-ignition or forced ignition.

[0003] The internal combustion engine may be a longitudinally scavenged two-stroke engine.

[0004] The term internal combustion engine also refers to large engines that can operate not only in a diesel mode characterized by auto-ignition of one fuel, but also in an Otto mode characterized by positive ignition of one fuel, or a mixture of the two. Furthermore, the term internal combustion engine specifically includes dual-fuel engines and large engines in which the auto-ignition of one fuel is used to positively ignite another fuel.

[0005] The engine speed is preferably less than 800 RPM, especially for four-stroke engines, and more preferably less than 200 RPM, especially for two-stroke engines, which refer to the designation of slow speed engines.

[0006] The fuel may be diesel, marine diesel, heavy fuel oil, emulsion fuel, slurry fuel, methanol, or ethanol, as well as gases such as liquefied natural gas (LNG) or liquid petroleum gas (LPG), and the like.

[0007] Further fuels that may be added on demand are LBG (Liquefied Biogas), biofuels (e.g. oils made from algae or seaweed), ammonia, hydrogen, CO2-derived synthetic fuels (e.g. made by Power-To-Gas or Power-To-Liquid). [Background technology]

[0008] Large ships, especially those for transporting goods, are usually powered by internal combustion engines, in particular diesel and / or gas engines, mainly two-stroke crosshead engines.

[0009] EP 2527611 A1 discloses an exhaust gas aftertreatment device for a large diesel engine, comprising an elongated exhaust manifold having a plurality of intake ports and a catalyst container. The exhaust manifold and the catalyst container are arranged essentially parallel to each other and separated from each other by at least one partition extending longitudinally within each case. The exhaust manifold is connected to the catalyst container via one or more holes in one or more partitions to guide the exhaust gases during operation through the catalyst element and to the corresponding outlets.

[0010] The apparatus includes at least one mixing tube, each extending from an exhaust gas collector through a passageway into a catalyst vessel, and each mixing tube having one or more nozzles for injecting a reducing agent.

[0011] This nozzle is located relatively close to the SCR (selective catalytic reduction) element, which results in insufficient mixing between the exhaust gas and the reductant, leading to the risk of the reductant slipping.

[0012] EP 2 860 369 A1 discloses an exhaust aftertreatment system including a directing device in an exhaust flow path upstream of a reductant opening into the exhaust flow path, the directing device configured to direct the exhaust flow toward and around the reductant opening to effectively mix the exhaust flow with the reductant provided through the reductant opening to reduce the formation of reductant deposits.

[0013] DE 112012003742 relates to an exhaust gas treatment system in which an exhaust gas flow modifier is provided upstream of a reactant injector to improve the dispersion of the reactants in the exhaust steam of the engine.

[0014] EP 2074293 A1 discloses an exhaust gas flow conditioner installed in an exhaust pipeline, which comprises a catalytic corrugated metal plate, the corrugation direction of the corrugated metal plate being angled toward the average flow direction of the exhaust gas in order to condition the exhaust gas flow at least in the lateral direction. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] European Patent Application Publication No. 2527611 [Patent Document 2] European Patent Application Publication No. 2860369 [Patent Document 3] German Patent No. 112012003742 [Patent Document 4] European Patent Application Publication No. 2074293 Summary of the Invention

[0016] The present invention is based on the object of providing an exhaust gas aftertreatment device and an internal combustion engine which avoids the disadvantages of known exhaust gas aftertreatment devices and internal combustion engines, and in particular which achieves sufficient and homogeneous mixing of exhaust gas with a reducing agent.

[0017] This object is achieved by the features of the independent claims.

[0018] In accordance with the present invention, an exhaust gas aftertreatment device to be used in an internal combustion engine includes an elongated exhaust manifold having a plurality of intake ports and a catalyst canister.

[0019] The exhaust manifold and the catalyst container are disposed adjacent to each other and side by side, and are separated from each other by at least one partition wall extending along the longitudinal direction.

[0020] Thus, the exhaust manifold and catalyst can each extend longitudinally rather than vertically.

[0021] The exhaust manifold is in fluid communication with the catalyst canister through at least one passageway in the partition wall for directing exhaust gases into the catalyst canister.

[0022] A passage valve may be disposed in the passage.

[0023] At least one reductant supply element, for example a urea injector, is disposed in the exhaust manifold within one intake port or adjacent to at least one intake port, preferably adjacent to all intake ports.

[0024] Within the scope of this application, "proximate the intake port" means that the flow path between the intake port and the reductant supply element is shorter than the flow path between the reductant supply element and the passage.

[0025] The intake port is disposed in the wall of the exhaust manifold to fluidly connect the exhaust outlet of the cylinder with the interior volume of the exhaust manifold. Exhaust gases may be directed into the exhaust manifold through the intake port.

[0026] At least one flow directing element is disposed within the exhaust manifold for directing exhaust gases toward the passage.

[0027] Because the reductant supply element is located within or near the intake port, it takes some time for the reductant to reach the passages, which is necessary for homogeneous mixing, especially when the reductant is admitted continuously, whereas the exhaust gases arrive on every stroke.

[0028] The exhaust gas and the reductant may be mixed within the exhaust manifold. However, because there may be more intake ports than reductant supply elements, some exhaust gas introduced into the exhaust manifold by intake ports without reductant supply elements or intake ports without nearby reductant supply elements may have less opportunity to come into contact with the reductant than exhaust gas introduced into the exhaust manifold by intake ports with reductant supply elements. The reductant may be unevenly distributed within the exhaust gas.

[0029] In particular, there may be a risk that exhaust gases that have not come into contact with any reducing agent will enter the passages and will escape from the exhaust gas aftertreatment device uncleaned.

[0030] The flow guide elements are arranged so that there is a certain minimum path between the intake port and the passage, and therefore a certain minimum duration that all exhaust gases, especially exhaust gases introduced by intake ports that do not have a reductant supply element, remain inside the exhaust manifold.

[0031] The flow directing elements provide an opportunity for the reductant to be well mixed and evenly distributed in the exhaust gas.

[0032] The flow directing element preferably provides a length of flow path that is located upstream of and immediately adjacent to the passage.

[0033] The exhaust gas aftertreatment device may comprise at least one flow directing element for each passage, so that there are no passages through which unmixed exhaust gas can enter the catalyst container.

[0034] The flow directing element may be an intake pipe having a first end open to the passage and a second end open to the exhaust manifold. The intake pipe forms an intake channel leading from an interior volume of the exhaust manifold to the passage. The length of the pipe defines a minimum path length, thereby allowing a certain minimum amount of time for the exhaust gas and the reductant to mix.

[0035] The flow guiding element may comprise a pipe wall arranged on the partition wall so as to guide the exhaust gases into a passage between the pipe wall and the partition wall. A part of the intake pipe is formed by the partition wall.

[0036] The flow guiding element, in particular the pipe wall, may be fixed inside the exhaust manifold so that the flow guiding element maintains its position when the internal combustion engine is in operation and when the internal combustion engine is moving due to wind and / or waves, in particular when a ship equipped with the internal combustion engine is underway. The flow directing element may be fixed inside the exhaust manifold by connection to the outer wall of the exhaust manifold and / or by connection to the partition wall.

[0037] The flow guiding element, in particular the pipe wall, may be fixed by clamping, a screw connection or welding. Preferably, there is a detachable connection between the flow guiding element and the exhaust manifold and / or the partition wall.

[0038] The flow directing element may be removed from the exhaust manifold for maintenance, cleaning, and / or replacement of the exhaust gas aftertreatment device.

[0039] The at least one reductant supply element may be disposed in an intermediate portion of the elongated exhaust manifold.

[0040] The exhaust gas aftertreatment device may include at least three intake ports arranged longitudinally alongside one another for delivering exhaust gas into the exhaust manifold, and each intake port may be fluidly connectable to or connected to a cylinder.

[0041] Preferably, at least one reductant supply element is located in a central one of the intake ports, the central intake port having at least one adjacent intake port on either side of it in the longitudinal direction.

[0042] The partition wall may include two passages disposed at each of the corresponding longitudinal ends of the exhaust manifold.

[0043] The central location of the reductant supply element and the location of the passages at the longitudinal ends provides a minimum path and therefore a minimum residence time of the reductant within the exhaust manifold, and in particular allows mixing of the reductant with the discontinuously admitted exhaust gas.

[0044] The exhaust manifold may include a bypass outlet having a valve. The bypass valve may be opened when exhaust scrubbing is not essential, for example when the engine is operating in tier 2 mode. In this case, the reductant may be turned off and the passage may be closed by a passage valve.

[0045] The exhaust gas aftertreatment device may include a louver valve for closing the passageway. The louver valve may be opened when the exhaust gas should be directed through the SCR element, for example, when the engine is operating in Tier 3 mode. When the engine is switched to Tier 2 mode, the louver valve may be closed and the bypass valve may be opened.

[0046] Typically, the louver valve does not close completely. Therefore, exhaust gases blowing directly from the intake port into the passageway may pass through the closed louver valve and enter the catalyst container. The flow guide element, as described above, may be positioned to prevent direct flow from the intake port to the passageway, thereby protecting the louver valve from unintentional opening. In this way, contamination of the SCR elements can be avoided.

[0047] The flow directing element reduces the effect of pressure fluctuations in the exhaust manifold on the louver valve.

[0048] The catalyst container may include two stacks of SCR elements and a central passage connected or connectable to the exhaust outlet. Exhaust gases may enter the catalyst container via two passages located at the longitudinal ends of the partition wall, may be guided through the two stacks of SCR elements, and may collect at the central passage.

[0049] The exhaust outlet and / or the bypass outlet may be fluidly connectable with or connected to an outlet pipe that may direct the exhaust gases towards the turbocharger.

[0050] The stacks of SCR elements may be disposed within a catalyst can. For example, at least three SCR elements may be disposed within one stack. The catalyst can may include rails for each stack to guide the stack along its length. The catalyst can may be openable at its longitudinal ends to allow for the removal and installation of stacks with SCR elements.

[0051] The SCR elements need to be placed very precisely inside the catalyst can with the shortest possible distance to the wall of the catalyst can and with a defined distance between them. Therefore, the catalyst elements may be arranged in a stack and fixed to a stack frame. The stack frame may provide counter elements, such as corresponding recesses, for the rails.

[0052] According to the invention, the internal combustion engine comprises at least one cylinder and at least one exhaust gas aftertreatment device as described above, in particular one exhaust gas aftertreatment device for up to eight cylinders, preferably one for up to six cylinders.

[0053] According to the method of the present invention, exhaust gas is introduced into an exhaust manifold through a plurality of intake ports, and a reductant is introduced through a reductant supply element. The method comprises at least the following steps:

[0054] The exhaust gas and the reducing agent are guided along the flow guiding element so that mixing of the exhaust gas and the reducing agent occurs at least while passing through the flow guiding element and before entering the catalyst container via the passage in the partition wall.

[0055] Further advantageous aspects of the invention are explained in the following by means of exemplary embodiments and drawings. [Brief explanation of the drawings]

[0056] [Figure 1] 1 is a schematic perspective view showing a first example of a combustion engine; [Figure 2] FIG. 1 is a schematic perspective view showing a first example of an exhaust gas aftertreatment device. [Figure 3] FIG. 3 is a schematic diagram showing a detail of the first example according to FIG. 2;

[0057] Figure 1 shows one embodiment of a large combustion engine 1. A large bore combustion engine typically includes one or more of the following components: a crankshaft rotatably mounted in a crankshaft housing 4, at least one crosshead, and at least one piston 2 movably disposed within a cylinder 3. Typically, the piston 2 connects to the crosshead within each housing via a piston rod 2a, which connects to and drives the crankshaft via a push rod within each housing. A combustion chamber is formed between the piston 2 and a cylinder cover 7.

[0058] Longitudinal scavenging of the cylinder chamber may be provided, i.e., as soon as the piston 2 is below the scavenging slot 3a, scavenging air flows from the scavenging chamber 5 through the scavenging slot 3a in the cylinder liner into the cylinder 3. The scavenging air flow causes the exhaust gases of combustion to pass through the exhaust valve 6 in the cylinder cover 7, through the intake port 11, and into the exhaust manifold 10 of the exhaust gas aftertreatment device 100.

[0059] The combustion engine 1 may further include a turbocharger 8, and the exhaust gas aftertreatment device 100 is arranged between the exhaust valve 6 of the combustion engine 1 and the turbocharger 8 for the exhaust gases. After the exhaust gases are expanded in the turbocharger 8, they may be discharged to the outside.

[0060] FIG. 2 is a schematic perspective view showing a first example of an exhaust gas aftertreatment device 100. As shown in FIG.

[0061] The exhaust gas aftertreatment device 100 includes an elongated exhaust manifold 10 having five intake ports 11 .

[0062] The exhaust gas aftertreatment device 100 further includes a catalyst container 20, which is disposed below the exhaust manifold 10 and separated from the exhaust manifold 10 by a partition wall 30 extending along the longitudinal direction L.

[0063] The exhaust manifold 10 is in fluid communication with the catalyst container 20 through two passages 31 provided in a partition wall 30 at each of the longitudinal ends of the exhaust manifold 10 .

[0064] Reductant supply elements 12 are disposed inside the two central intake ports 11c.

[0065] A flow directing element 15 is disposed within the exhaust manifold 10 for directing the exhaust gases towards the passage 31 .

[0066] Each flow guiding element 15 comprises a pipe wall 19 arranged in a partition wall 30 so as to guide exhaust gases into a passage 31 between the pipe wall 19 and the partition wall 30. The pipe wall 19 and the partition wall 30 form an intake pipe 18 having a first end 16 that opens into the passage 31 and a second end 17 that opens into the exhaust manifold 10.

[0067] Without the flow directing element 15, exhaust gas entering the exhaust manifold 10 through one of the outermost intake ports 11 would flow directly, in a short path, into the passage 31 below the corresponding intake port. The exhaust gas would not mix with the reductant admitted by the reductant supply element 12 of the central intake port 11c.

[0068] The flow directing elements 15 redirect the exhaust gases from the outermost intake ports 11 towards the middle section 13 of the elongated exhaust manifold 10, allowing sufficient time for the exhaust gases to mix with the reductant.

[0069] Pipe wall 19 covers passage 31, which may generally be closed by a louver valve not explicitly shown. When the engine is operating in Tier 2 mode with no reductant supplied, bypass 32 is open, the louver valve is closed, and pipe wall 19 prevents exhaust gases that might overcome the closed louver valve from blowing directly from outermost intake port 11 into passage 31.

[0070] When the engine is operating in tier three mode, exhaust gas mixed with reductant enters the catalyst vessel 20 via two passages 31 and passes through three SCR elements 22 arranged in a stack 21.

[0071] The SCR elements 22 are arranged on a stack frame 26 that is guided along rails 25 inside the catalyst vessel 20 .

[0072] The stack 21 can be removed from the catalyst container 20 by opening the cover 27 at the end of the catalyst container 20 in the longitudinal direction.

[0073] The cleaned exhaust gas arrives at the central passage 23 and exits the exhaust gas aftertreatment device 100 via the exhaust outlet 24 .

[0074] FIG. 3 shows a schematic diagram of a detail of the first example according to FIG.

[0075] The pipe wall 19 of the flow guiding element 15 is fixed to the partition wall 30 by clamping. The pipe wall 19 is provided with a clamping element 33, which snaps into a bracket 34 arranged and fixed on the partition wall 30.

[0076] For maintenance purposes, the covers 35 at the longitudinal ends of the exhaust manifold 10 may be removed, the pipe wall 19 may be pulled out of the exhaust manifold 10, and the louver valves (not shown) for closing the passages 31 may be cleaned or replaced, after which the pipe wall 19 may be reinserted.

[0077] Exhaust gases entering the exhaust manifold 10 through the outermost intake port 11 are redirected by the flow directing element 15 to take a detour 36 through the open end 17 of the intake pipe 18, formed by the pipe wall 19 and the partition wall 30, and pass through the passage 31. [Explanation of symbols]

[0078] 1. Combustion engine 2 pistons 2a Piston rod 3 cylinders 3a Scavenging slot 4 Crankshaft housing 5. Scavenging sump 6 Exhaust valve 7 Cylinder cover 8 Turbocharger 10 Exhaust manifold 11 Intake port 11c intake port 12 Reductant supply factors 13 Middle section 15 Guidance elements 16 First end 17 Second end 18 Intake pipe 19 Pipe wall 20 Catalyst container 21 Laminate 22 SCR elements 23 Central aisle 24 exhaust outlet 25 Rail 26 Laminated Frame 27 Cover 30 Partition Wall 31 Passage 32 Bypass 33 Clamping element 34 Bracket 35 Cover 36 Detour 100 Exhaust gas aftertreatment device

Claims

1. An exhaust gas aftertreatment device (100) for an internal combustion engine having an elongated exhaust manifold (10) having a plurality of intake ports (11) and a catalyst container (20), comprising: The exhaust manifold (10) and the catalyst container (20) are arranged side by side adjacent to each other and separated from each other by at least one partition wall (30) extending along a longitudinal direction (L); the exhaust manifold (10) is in fluid communication with the catalyst container (20) through at least one passage (31) provided in the partition wall (30) for guiding exhaust gas into the catalyst container (20); An exhaust gas aftertreatment device (100) in which at least one reductant supply element (12) is disposed in the exhaust manifold (10) within or near at least one of the intake ports (11), 1. An exhaust gas aftertreatment device (100), characterized in that at least one flow guiding element (15) is arranged in said exhaust manifold (10) for guiding exhaust gases towards said passage (31).

2. 2. The exhaust gas aftertreatment device (100) of claim 1, wherein the exhaust gas aftertreatment device (100) comprises at least one flow directing element (15) for each of the passages (31).

3. 2. The exhaust gas aftertreatment device according to claim 1, wherein the flow guiding element (15) is an intake pipe (18) having a first end (16) that is open toward the passage (31) and a second end (17) that is open toward the exhaust manifold (10).

4. 4. The exhaust gas aftertreatment device according to claim 3, wherein the flow guiding element (15) has a pipe wall (19) arranged on the partition wall (30) so as to be able to guide the exhaust gas into the passage (31) between the pipe wall (19) and the partition wall (30).

5. 2. The exhaust gas aftertreatment device of claim 1, wherein the at least one reductant supply element (12) is disposed in a middle portion (13) of the elongated exhaust manifold (10).

6. 2. The exhaust gas aftertreatment device according to claim 1, wherein the exhaust gas aftertreatment device (100) comprises at least three intake ports (11) arranged side by side in the longitudinal direction (L) for feeding exhaust gas into the exhaust manifold (10).

7. An exhaust gas aftertreatment device as described in Claim 6, wherein the at least one reductant supply element (12) is arranged within one of the central intake ports (11c).

8. 2. The exhaust gas aftertreatment device according to claim 1, wherein the partition wall (30) has two of the passages (31) arranged at each of the longitudinal ends of the exhaust manifold (10).

9. The exhaust gas aftertreatment device of claim 1, wherein the exhaust manifold (10) comprises a bypass outlet (32) having a bypass valve.

10. 2. The exhaust gas aftertreatment device of claim 1, wherein the exhaust gas aftertreatment device (100) comprises a louver valve for closing the passage (31).

11. 2. The exhaust gas aftertreatment device according to claim 1, wherein the catalyst container (20) comprises two stacks (21) of SCR (Selective Catalytic Reduction) elements (22) and a central passage (23) connected or connectable to an exhaust outlet (24).

12. 2. The exhaust gas aftertreatment device according to claim 1, wherein the stack (21) of the SCR elements (22) is arranged in the catalyst container (20), and the catalyst container (20) has rails (25) for each of the stacks (21) to guide the stacks (21) along the longitudinal direction (L).

13. An internal combustion engine (1) comprising at least one cylinder (3) and at least one exhaust gas aftertreatment device (100) according to claim 1.

14. An internal combustion engine (1) as described in claim 13, comprising one exhaust gas aftertreatment device (100) for up to eight of the cylinders (3).

15. 2. A method for exhaust gas aftertreatment in an exhaust gas aftertreatment device (100) according to claim 1, comprising: guiding exhaust gas into the exhaust manifold (10) through the plurality of intake ports (11); and introducing a reducing agent through the reductant supply element (12); guiding exhaust gas and reducing agent along the flow directing element (15) such that mixing of the exhaust gas and reducing agent occurs at least while passing through the flow directing element (15) and before entering the catalyst vessel (20) via the passage (31) in the partition wall (30).

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