JP6966672B2 - 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. Further, the present invention relates to an internal combustion engine having an exhaust gas aftertreatment system.

For example, the combustion process of a stationary internal combustion engine used in a power plant, and the combustion process of a non-stationary internal combustion engine used in a ship, for example, produce nitrogen oxides, which are typically coal. Occurs during combustion of sulfur-containing fossil fuels such as bitumenous coal, lignites, petroleum, heavy oil or diesel fuels. Therefore, an exhaust gas aftertreatment system is assigned to this type of internal combustion engine, which is used for purifying the exhaust gas leaving the internal combustion engine, especially for removing nitrogen.

In order to reduce nitrogen oxides in exhaust gas, what is known as an SCR catalytic converter is mainly used in actually known exhaust gas aftertreatment systems. In the SCR catalytic converter, selective catalytic reduction of nitrogen oxides occurs, and ammonia (NH ₃ ) is required as a reducing agent for the reduction of nitrogen oxides. 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 for this purpose, and the ammonia or ammonia precursor is the SCR catalytic converter. It is mixed with exhaust gas upstream. For this purpose, a mixing section is actually provided between the introduction of ammonia or ammonia precursor and the SCR catalytic converter.

Although the exhaust gas aftertreatment has already been successfully carried out by using the actually known exhaust gas aftertreatment system, it is necessary to further improve the exhaust gas aftertreatment system. In particular, a compact design of such an exhaust gas aftertreatment system is required.

In view of this, the present invention is based on the object of creating a new exhaust gas aftertreatment system. This object is achieved by the exhaust gas aftertreatment system according to claim 1. According to the present invention, the downstream end of the exhaust gas supply line is open in the reactor chamber containing the SCR catalytic converter, and the exhaust gas supply line has an opening adjacent to the downstream end, which is exhaust. Allows the inflow of exhaust gas into the reactor chamber upstream of the downstream end of the gas supply line. The compact design can guarantee effective exhaust gas post-treatment.

According to the advantageous deployment, the exhaust gas flow flowing into the reactor chamber through the downstream end of the exhaust gas supply line and the exhaust gas flow flowing into the reactor chamber through the opening are mixed in the reactor chamber. And can be induced via an SCR catalytic converter. The compact design can guarantee effective exhaust gas post-treatment.

According to favorable deployments, the exhaust gas supply line and the exhaust gas exhaust line act on the common surface of the reactor chamber, and the exhaust gas exhaust line relates to the exhaust gas flow, and this common surface of the reactor chamber downstream of the SCR catalytic converter. Into the reactor chamber, and the downstream end of the exhaust gas supply line, with respect to the exhaust gas flow, into the reactor chamber at the surface of the reactor chamber opposite this shared surface of the reactor chamber upstream of the SCR catalytic converter. The exhaust gas supply line, which is open and has a mixing section, extends through the SCR catalytic converter, and the compact design can ensure effective exhaust gas post-treatment.

The exhaust gas supply line preferably has an opening in a section located between the SCR catalytic converter and the downstream end of the exhaust gas supply line, and the exhaust gas flowing through this opening is SCR with respect to the exhaust gas flow. It flows into the reactor chamber upstream of the catalytic converter. The compact design can guarantee effective exhaust gas post-treatment.

According to a further advantageous embodiment, the baffle element interacts with the downstream end of the exhaust gas supply line, which diverts the exhaust gas flow out of the exhaust gas supply line through the downstream end. The compact design can guarantee effective exhaust gas post-treatment.

The internal combustion engine according to the present invention is defined in claim 9.

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

It is a schematic perspective view of the internal combustion engine provided with the exhaust gas aftertreatment system which concerns on this invention. It is a detailed view of the exhaust gas aftertreatment system of FIG. It is a detailed view of FIG. It is a further detailed view of the exhaust gas aftertreatment system which concerns on this invention.

The present invention relates to an exhaust gas aftertreatment system for an internal combustion engine, and thus a stationary internal combustion engine in a power plant or a non-stationary internal combustion engine used in a ship. In particular, exhaust gas aftertreatment systems are used in marine diesel internal combustion engines operated on heavy fuel oils.

FIG. 1 shows a device composed of an internal combustion engine 1 including an exhaust gas turbocharging system 2 and an exhaust gas aftertreatment system 3. The internal combustion engine 1 may be a non-stationary or stationary internal combustion engine, particularly a marine internal combustion engine operated in a non-stationary mode. The exhaust gas discharged from the cylinder of the internal combustion engine 1 is used in the exhaust gas filling system 2 to obtain mechanical energy from the thermal energy of the exhaust gas in order to compress the supply air supplied by the internal combustion engine 1. .. Therefore, FIG. 1 shows an internal combustion engine 1 provided with an exhaust gas turbocharged system 2, which is a plurality of exhaust gas turbochargers, namely a first high pressure side exhaust gas turbocharger 4 and a second low pressure side exhaust gas. It is equipped with a turbocharger 5. Exhaust gas leaving the cylinder of the internal combustion engine 1 first flows through the high-pressure turbine 6 of the first exhaust gas turbocharger 1, where it expands, and the energy obtained there first compresses the supply air. It is used in the high pressure compressor of the exhaust gas turbocharger 4.

Looking in the flow direction of the exhaust gas, the second exhaust gas turbocharger 5 is arranged downstream of the first exhaust gas turbocharger 4, and after that, the high-pressure turbine of the first exhaust gas turbocharger 4 has already passed. The second exhaust gas turbocharger exhaust gas that has passed through 6 is guided, that is, is guided 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 is further expanded, and the energy obtained thereby compresses the supply air supplied to the cylinder of the internal combustion engine 1 in the same manner. It is used in the low pressure compressor of the second exhaust gas turbocharger 5.

In addition to the exhaust gas filling system 2 having two exhaust turbochargers 4 and 5, the internal combustion engine 1 includes an exhaust gas aftertreatment system 3 which is an SCR exhaust gas aftertreatment system. In the illustrated exemplary embodiment, 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 turbocharger 5, resulting in a first. Exhaust gas leaving the high pressure turbine 6 of the exhaust gas turbocharger 4 therefore causes the SCR exhaust gas aftertreatment system 3 before the exhaust gas reaches the region of the low pressure turbine 7 of the second exhaust gas turbocharger 4. You can be guided first through. FIG. 1 shows an exhaust gas supply line 8, through which exhaust gas starts from the high pressure turbine 6 of the first exhaust gas turbocharger 4 and of the SCR catalytic converter 9 arranged in the reactor chamber 10. Can be guided in the direction. Further, FIG. 1 shows an exhaust gas discharge line 11, which is used to discharge the exhaust gas from the SCR catalytic converter 9 toward the low pressure turbine 7 of the second exhaust gas turbocharger 5. Starting from the low pressure turbine 7, the exhaust gas flows through the line 26, especially to the outside. The present invention is not limited to an internal combustion engine having such a two-stage exhaust gas turbocharging system. The present invention can also be used in an internal combustion engine equipped with a single-stage exhaust gas turbocharging system capable of connecting the SCR catalytic converter 9 to an exhaust gas stream upstream or downstream of the turbine of the exhaust gas turbocharger.

The exhaust gas supply line 8 extending to the reactor chamber 10 and thus to the SCR catalytic converter 9 located within the reactor chamber 10, and the exhaust gas discharge line 11 extending away from the reactor chamber 10 and thus away from the SCR catalytic converter. Preferably, it is connected via a bypass line 12, in which the blocking device 13 is incorporated. When the shutoff device 13 is closed, the bypass line 12 is closed and the exhaust gas cannot flow through the bypass line. In contrast, when the shutoff device 13 is open, the exhaust gas passes through the bypass line 12, specifically through the reactor chamber 10, and thus through the SCR catalytic converter 9 located within the reactor chamber 10. Can flow.

As described, the exhaust gas supply line 8 and the exhaust gas exhaust line 11 pass through the reactor chamber 10 when the bypass 12 is open and thus through the SCR catalytic converter 9 to carry the exhaust gas. Can be combined by. In this case, the exhaust gas supply line 8 and the exhaust gas discharge line 11 act on the common surface 28 of the reactor chamber 10 accommodating the SCR catalytic converter 9. As a result, the long bypass line of the bypass 12 between the exhaust gas supply line 8 and the exhaust gas discharge line 11 extending around the reactor chamber 10 accommodating the SCR catalytic converter 9 can be eliminated. Therefore, the bypass 12 can be realized in a short and compact manner, and in the case of a compact design, effective exhaust gas post-treatment is possible.

The exhaust gas supply line 8 and the exhaust gas discharge line 11 are on the common surface 28 of the reactor chamber 10 accommodating the SCR catalytic converter 9, and the exhaust gas discharge line 11 is located downstream of the SCR catalytic converter 9 with respect to the exhaust gas flow. In this shared surface of the reactor chamber, the downstream end 15 of the exhaust gas supply line 8 opens into the reactor chamber and is upstream of the SCR catalytic converter 9 with respect to the exhaust gas flow and opposite to the shared surface 28 of the reactor chamber 10. It acts to open into the reactor chamber 10 on surface 29 of 10. The exhaust gas supply line 8 extends through the SCR catalytic converter 9. The exhaust gas discharge line 11 concentrically surrounds the exhaust gas supply line 8 on the radial outside in a region extending outside the reactor chamber 10 adjacent to a particular section, specifically the surface 28. .. In the illustrated exemplary embodiment, the bypass 12 is provided in a region where the exhaust gas discharge line 11 is arranged adjacent to a region concentrically surrounding the exhaust gas supply line 8. Therefore, effective exhaust gas post-treatment is possible with a compact design.

In contrast, the bypass 12 may be provided in a region where the exhaust gas discharge line 11 concentrically surrounds the exhaust gas supply line 8 on the outside.

The introduction device 16 is assigned to the exhaust gas supply line 8 of the exhaust gas aftertreatment system 3, which allows the introduction device to introduce a reducing agent, particularly ammonia (NH ₃ ) or an ammonia precursor, into the exhaust gas stream. This is required to convert the nitrogen oxides of the exhaust gas in the manner specified in the area of the SCR catalytic converter 9. The introduction device 16 of the exhaust gas aftertreatment system 3 is preferably an injection nozzle, whereby ammonia or an ammonia precursor is injected into the exhaust gas stream in the exhaust gas supply line 8. In FIG. 2, a cone 17 is used 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 and upstream of the SCR catalytic converter 9 when viewed in the flow direction is referred to as a mixing section 18 or a decomposition section. In particular, the exhaust gas supply line 8 provides a mixing section 18 downstream of the introduction device 16, where the exhaust gas can be mixed with the reducing agent upstream of the SCR catalytic converter 9. The mixing section 18, and thus the exhaust gas supply line 8, is externally surrounded by the SCR catalytic converter 9 in one section, here in the form of individual catalytic converter modules. In this section, the SCR catalytic converter 9 heats the mixing section 18. The flow directions of the exhaust gas in the regions of the mixing section 18 and the SCR catalytic converter 9 are opposite.

The exhaust gas supply line 8 is opened in the reactor chamber 10 by the downstream end portion 15. The exhaust gas supply line 8 has an opening 27 adjacent to the downstream end 15, which allows exhaust gas to flow into the reactor chamber 10 upstream of the downstream end 15 of the exhaust gas supply line 8. .. The exhaust gas flow flowing into the reactor chamber 10 through the downstream end 15 of the exhaust gas supply line 8 and the exhaust gas flow flowing into the reactor chamber 10 through the opening 27 are the exhaust gas flow upstream of the SCR catalytic converter 9. It can be mixed within and guided via the SCR catalytic converter 9. 2 and 4 use arrows 14 to clarify the flow of exhaust gas. Therefore, gas post-treatment is possible with a very compact design.

The exhaust gas supply line 8 has an opening 27 in a section located between the SCR catalytic converter 9 and the downstream end 16 of the exhaust gas supply line 8. The exhaust gas flowing through the opening 27 flows into the reactor chamber 10 on the upstream side of the SCR catalytic converter 9 with respect to the exhaust gas flow. Therefore, effective exhaust gas post-treatment is possible with a very compact design. The exhaust gas supply line 8 is located at the upstream mixing section 18 or decomposition section of the downstream end 15 of the exhaust gas supply line 8, preferably at the end or rear third of the mixing section 18 or decomposition section. It preferably has an opening 27 at the end or at the rear quarter. Therefore, effective exhaust gas post-treatment is possible with a very compact design.

Both the SCR catalytic converter 9 and, at least to some extent, the mixing section 18 or the decomposition section are housed in the reactor chamber 10, and thus in the shared housing formed by the walls of the reactor chamber 10.

Although the baffle element 19 is assigned to the downstream end 15 of the exhaust gas supply line 8, the baffle element is preferably displaceable with respect to the downstream end 15 of the exhaust gas supply line 8. In the preferred exemplary embodiment illustrated, the baffle element 19 acts on the baffle element 19 specifically via the piston rod 21 and is a pneumatic adjusting cylinder extending through the wall 22 of the reactor chamber 10 in the region of the surface 29 of the reactor chamber 10. 20 can be used to linearly displace the downstream end 15 of the exhaust gas supply line 8 opening into the reactor chamber 10 in the direction of the bidirectional arrow 25. The seal 23 seals the piston rod 21 of the pneumatic cylinder 20 through which the piston rod penetrates the wall 22 of the reactor chamber 10. Due to the relative position of the baffle element 19 with respect to the downstream end 15 of the exhaust gas supply line 8, the exhaust gas redirected in the region of the downstream end 15 of the exhaust gas supply line 8 in the region of the baffle element 19 is radial. Whether or not the direction of the section arranged inside is stronger or the direction of the section arranged radially outside the SCR catalytic converter 9 is stronger, and compared with the downstream end 15 of the exhaust gas line 8. Then, it is possible to determine how much exhaust gas flows through the opening 27.

The baffle element 19 can be inflated at least on the side facing the downstream end 15 of the exhaust gas supply line 8 which forms a flow guide for the exhaust gas, preferably in a bell shape. Therefore, especially from FIGS. 3 and 4, in particular, the surface 24 of the baffle element 19 facing the downstream end 15 of the exhaust gas supply line 8 is radially inside the baffle element 19 with respect to the radial outer section of the baffle element 19. It can be seen in the section that it has a smaller distance from the downstream end 15 of the exhaust gas supply line 8.

The baffle element 19 is recessed or bulged at the center of the surface 24 in the direction of the downstream end 15 of the exhaust gas supply line 8, which is opposite to the flow direction of the exhaust gas. The liquid reducing agent droplets present in the exhaust gas flow do not flow through the opening 27, but rather collide with and capture the surface 24 of the baffle element 19 facing the downstream end 15 of the exhaust gas supply line 8. And atomized to prevent such droplets of liquid reducing agent from reaching the region of the SCR catalytic converter 9.

The baffle element 19 prevents the exhaust gas flow from stalling downstream of the downstream end 15 of the exhaust gas supply line 8 in the case of a small pressure loss. The distance between the baffle element 19 and the downstream end 15 of the exhaust gas supply line 8 is the region of the baffle element 19 with the lowest possible pressure loss, specifically with a pressure loss of less than 10 mbar. Especially at least 100 mm in order to guarantee the direction change of the exhaust gas flow. In the region of the baffle element 19, and thus the surface 29 of the reactor chamber 10, the exhaust gas is altered by 180 ° or about 180 °.

The baffle element 19 can have a catalytic coating in the region of the surface 24 facing the downstream end 15 of the exhaust gas supply line 8 to improve the exhaust gas post-treatment.

According to one embodiment of the invention, the exhaust gas supply line 8 is funnel-shaped in the region of its downstream end 15 to form a diffuser. As a result, the flow cross-sectional area of the exhaust gas supply line 8 is expanded in the region of the downstream end portion 15, but as can be seen from FIG. 2, especially when viewed in the flow direction of the exhaust gas, it is downstream of the exhaust gas supply line 8. Upstream of the side end 15, the flow cross-sectional area may be reduced first. Therefore, FIG. 2 shows that the flow cross section of the exhaust gas supply line 8 is initially substantially constant downstream of the introduction device 16 for the reducing agent when viewed in the direction of the exhaust gas flow, and then gradually tapers. And finally show that it spreads in the region of the downstream end 15. This enlargement of the flow section at the downstream end 15 of the exhaust gas supply line 8 is preferably in this example an exhaust gas supply rather than a section where the exhaust gas supply line 8 first tapers in front of the downstream end 15. It occurs over a shorter section of line 8. As can be best seen from FIG. 4, the enlargement of the downstream end 15 of the exhaust gas supply line 8 and the bell-shaped contour of the surface 24 of the baffle element 19 are preferably continuous or uniform, i.e. discontinuous. Formed without accompaniment.

In the internal combustion engine 1 of FIG. 1, the exhaust gas aftertreatment system 3 is arranged upright above the exhaust gas filling system 2. Access to the cylinder of the internal combustion engine 1 is free, but the accessibility of the exhaust turbochargers 4 and 5 is limited. However, the reactor chamber 10 can be easily disassembled when the maintenance work required for the exhaust gas turbochargers 4 and 6 is performed. In contrast to the upright arrangement of the exhaust gas aftertreatment system 3 on the exhaust gas filling system 2 shown in FIG. 1, the 90 ° tilted sideways arrangement of the exhaust gas aftertreatment system 3 adjacent to the exhaust gas filling system 2 is also possible. It is possible, but in such a sideways arrangement, the length of the device will be large. In this case, the internal combustion engine 1 and the exhaust gas filling system 2 do not require the reactor chamber 10 to be disassembled and can be used without restrictions for maintenance work.

The present invention is particularly used in internal combustion engines operated with excess air, preferably in marine diesel internal combustion engines operated with heavy oil or residual oil.

1 Internal combustion engine 2 Exhaust gas filling system 3 Exhaust gas aftertreatment system 4 Exhaust gas turbocharger 5 Exhaust gas turbocharger 6 High pressure turbine 7 Low pressure turbine 8 Exhaust gas supply line 9 SCR catalytic converter 10 Reactor chamber 11 Exhaust gas exhaust line 12 Bypass line 13 Shutoff device 14 Exhaust gas duct 15 End 16 Introductory device 17 Injection cone 18 Mixing section 19 Baffle element 20 Pneumatic cylinder 21 Piston rod 22 Wall 23 Seal 24 face 25 Displacement direction 26 line 27 Open 28 face 29 face

Claims (11)

The exhaust gas aftertreatment system (3) of the internal combustion engine, that is, the SCR exhaust gas aftertreatment system of the internal combustion engine.
With SCR catalytic converter (9)
The exhaust gas supply line (8) extending to the SCR catalytic converter (9) and
An exhaust gas discharge line (11) extending in a direction away from the SCR catalytic converter (9),
An introduction device (16) assigned to the exhaust gas supply line (8) to introduce a reducing agent into the exhaust gas, and
A mixing section (18) provided by the exhaust gas supply line (8) downstream of the introduction device (16) to mix the exhaust gas with the reducing agent upstream of the SCR catalytic converter (9). Have and
The downstream end (15) of the exhaust gas supply line (8) is open in the reactor chamber (10) accommodating the SCR catalytic converter (9), and the exhaust gas supply line (8) is An opening (10) adjacent to the downstream end (15) that allows exhaust gas to enter the reactor chamber (10) upstream of the downstream end (15) of the exhaust gas supply line (8). In the exhaust gas aftertreatment system having 27),
The baffle element (19) that changes the direction of the exhaust gas flow discharged from the exhaust gas supply line (8) through the downstream end portion (15) is the downstream end portion (15) of the exhaust gas supply line (8). ) And interact with
The exhaust gas aftertreatment system, wherein the baffle element (19) is displaceable with respect to the downstream end portion (15) of the exhaust gas supply line (8). The exhaust gas flow flowing into the reactor chamber (10) through the downstream end (15) of the exhaust gas supply line (8) and into the reactor chamber (10) via the opening (27). The inflowing exhaust gas flow is characterized in that it can be mixed in the reactor chamber (10) upstream of the SCR catalytic converter (9) and can be guided via the SCR catalytic converter (9). The exhaust gas aftertreatment system according to claim 1. The exhaust gas supply line (8) and the exhaust gas discharge line (11) act on the common surface (28) of the reactor chamber (10) accommodating the SCR catalytic converter (9), and the exhaust gas discharge line. (11) opens into the reactor chamber (10) at the shared surface (28) of the reactor chamber (10) downstream of the SCR catalytic converter (9) with respect to the exhaust gas flow, and said. The downstream end (15) of the exhaust gas supply line (8) is the reactor chamber opposite to this shared surface (28) of the reactor chamber (10) upstream of the SCR catalytic converter (9) with respect to the exhaust gas flow. The mixing section (18) of the exhaust gas supply line (8) is open into the reactor chamber (10) on the surface (29) of (10) and passes through the SCR catalytic converter (9). The exhaust gas aftertreatment system according to claim 1 or 2 , wherein in the case of a plurality of SCR catalytic converters, they extend through the region of the SCR catalytic converter (9). The exhaust gas supply line (8) has the opening (27) in a section located between the SCR catalytic converter (9) and the downstream end ( 15) of the exhaust gas supply line (8). The exhaust gas aftertreatment system according to claim 3 , wherein the exhaust gas aftertreatment system is characterized. The exhaust according to claim 4 , wherein the exhaust gas flowing through the opening (27) flows into the reactor chamber (10) upstream of the SCR catalytic converter (9) with respect to the exhaust gas flow. Gas aftertreatment system. The exhaust gas aftertreatment system according to any one of claims 3 to 5 , wherein the exhaust gas flows in the region of the mixing section (18) and the region of the SCR catalytic converter (9) are opposite to each other. .. One of claims 3-6 , wherein the wall of the reactor chamber (10) forms a shared housing for the SCR catalytic converter (9) and at least the section of the mixing section (18). Exhaust gas aftertreatment system described in. A bypass (12) for the SCR catalytic converter (9) or reactor chamber (10) is provided between the exhaust gas supply line (8) and the exhaust gas discharge line (11) to provide a cutoff device (12). The exhaust gas aftertreatment system according to any one of claims 1 to 7 , wherein 13) is connected to the bypass (12). An internal combustion engine (1) having an exhaust gas aftertreatment system (3) according to any one of claims 1 to 8. The internal combustion engine according to claim 9 , wherein the exhaust gas aftertreatment system (3) is attached upstream of at least one exhaust gas turbocharger (5). The internal combustion engine is a multi-stage exhaust gas filling 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 9 or 10 , wherein the exhaust gas aftertreatment system (3) is connected between the high-pressure turbine (6) and the low-pressure turbine (7). ..

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