KR102518200B1 - Exhaust gas after-treatment system and internal combustion engine - Google Patents

Abstract

The present invention, the SCR catalytic converter (9); an exhaust gas supply line 8 leading to the SCR catalytic converter 9; an exhaust gas discharge line 11 away from the SCR catalytic converter 9; an inlet device 16 mounted on the exhaust gas supply line 8 for introducing a reducing agent, in particular ammonia or ammonia precursor material, into the exhaust gas; a mixing section 18 for mixing the exhaust gas with the reducing agent upstream of the SCR catalytic converter 9 provided by the exhaust gas supply line 8 downstream of the inlet device 16; An exhaust gas aftertreatment system of an internal combustion engine comprising an exhaust gas aftertreatment system, in short, an SCR exhaust gas aftertreatment system, wherein the exhaust gas supply line 8 has, at the downstream end 15, a reactor chamber accommodating an SCR catalytic converter 9 ( 10) and the baffle member 19, which is displaceable relative to the downstream end 15 of the exhaust gas supply line 8, interacts with said end 15 of the exhaust gas supply line 8. do.

Description

Exhaust gas after-treatment system and internal combustion engine {EXHAUST GAS AFTER-TREATMENT SYSTEM AND INTERNAL COMBUSTION ENGINE}

The present invention relates to an exhaust gas aftertreatment system for an internal combustion engine. The invention also relates to an internal combustion engine equipped with an exhaust gas aftertreatment system.

In combustion processes in stationary internal combustion engines, eg used in power plants, and in non-stationary internal combustion engines, eg used in ships, nitrogen oxides are produced, typically from charcoal, It is produced during the combustion of fossil fuels containing sulfur, such as coal, lignite, petroleum, heavy oil or diesel fuel. Therefore, the internal combustion engines are equipped with exhaust gas after-treatment systems used for purification of exhaust gas discharged from the internal combustion engine, in particular for denitrification treatment.

For the reduction of nitrogen oxides in the exhaust gas, in particular so-called SCR catalytic converters are used in exhaust gas aftertreatment systems known in practice. In the SCR catalytic converter, selective catalytic reduction of nitrogen oxide is performed, and ammonia (NH ₃ ) is required as a reducing agent for reduction of nitrogen oxide. To this end, ammonia or an ammonia precursor substance, for example urea, is introduced into the exhaust gas in liquid form upstream of the SCR catalytic converter, and the ammonia or ammonia precursor substance is mixed with the exhaust gas upstream of the SCR catalytic converter. To this end, according to practice, mixing sections are provided between the inlet of ammonia or ammonia precursor material and the SCR catalytic converter.

Although exhaust aftertreatment, in particular nitrogen oxide reduction, can already be carried out successfully by means of exhaust aftertreatment systems known in practice and comprising SCR catalytic converters, it is of interest to continue improving exhaust aftertreatment systems. there is a need for In particular, there is a need for compact structural shapes of the exhaust gas aftertreatment systems.

An object of the present invention is to provide a new type of exhaust gas aftertreatment system for an internal combustion engine based on the prior art.

The problem is solved by an exhaust gas aftertreatment system for an internal combustion engine according to claim 1 . According to the present invention, the exhaust gas supply line leads at its downstream end into a reactor chamber accommodating the SCR catalytic converter, and is a baffle element displaceable relative to the downstream end of the exhaust gas supply line. ) interacts with the downstream end of the exhaust gas supply line. The baffle member disposed at the downstream end of the exhaust gas supply line leading into the reactor chamber can, on the one hand, ensure proper mixing of the reducing agent and the exhaust gas, even under conditions where the mixing section is shortened, and on the other hand in the SCR catalytic converter. A fixed flow of can be guaranteed. Effective exhaust gas aftertreatment can be ensured even with a compact construction geometry.

According to a preferred refinement, the baffle member can be displaced relative to the downstream end of the exhaust gas supply line, to block the exhaust gas supply line at its downstream end, or to open the exhaust gas supply line at its downstream end. and the position of the baffle element relative to the downstream end of the exhaust gas supply line when the exhaust gas supply line is open is preferably dependent on the exhaust gas mass flow and/or depending on the exhaust gas temperature and/or the exhaust gas It is determined by the amount of reducing agent introduced into the mass stream. In this way, a particularly effective exhaust gas aftertreatment is possible even in the compact structural form of the exhaust gas posttreatment system.

According to a preferred refinement, the downstream end of the exhaust gas supply line is enlarged in the form of a funnel to form a diffuser. The baffle member is curved on the side facing the exhaust gas supply line towards the downstream end of the exhaust gas flow and the reducing agent to form a flow guide surface, in particular curved in a bell-shaped manner. is formed These details also allow effective exhaust gas aftertreatment, even in short mixing sections, as a result of defined flow guides in the region of the baffle element and at the downstream end of the exhaust gas supply line towards the baffle element.

According to a further preferred refinement, a bypass line for the SCR catalytic converter is connected between the exhaust gas supply line and the exhaust gas discharge line, and a blocking member is connected in the bypass line, the position of which blocking member is positioned in the exhaust gas discharge line. It is determined according to the position of the baffle member relative to the downstream end of the gas supply line. By means of the bypass, excess exhaust gases can be directed to bypass the SCR catalytic converter if assemblies that are still cold in the region of the turbocharger of the internal combustion engine are to be heated, in particular after start-up of the internal combustion engine.

According to a further preferred refinement, the baffle element is provided with a catalyst coating layer at least on the side towards the downstream end of the exhaust gas supply line. In this way, exhaust gas aftertreatment can be further improved.

An internal combustion engine according to the invention is defined in claim 12 .

Advantageous refinements of the invention are presented in the dependent claims and the following description. Embodiments of the present invention are described in more detail with reference to the drawings, without being limited to these embodiments.

1 is a schematic perspective view showing an internal combustion engine equipped with an exhaust gas aftertreatment system according to the present invention.
FIG. 2 is a detailed view of the exhaust gas aftertreatment system of FIG. 1 .
Figure 3 is a detailed view of Figure 2;
4 is a further detailed view of an exhaust gas aftertreatment system according to the present invention.

The present invention relates to an exhaust gas aftertreatment system of an internal combustion engine, for example, a stationary internal combustion engine installed in a power generation facility or a non-stationary internal combustion engine used in a ship. In particular, the exhaust gas aftertreatment system is used in marine diesel internal combustion engines that operate on heavy fuel oil. In the following, the method of the present invention is more precisely described in conjunction with SCR technology, but it is not limited to said SCR technology, but can also be used in CH4 and HCHO oxidation catalytic converters, such as those used in gas engines.

1 shows an arrangement consisting of an internal combustion engine 1 equipped with 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, in particular a ship internal combustion engine operated in a non-stationary system. The exhaust gas discharged from the cylinders of the internal combustion engine (1) obtains, in the exhaust gas charging system (2), from the thermal energy of the exhaust gas, mechanical energy for compressing the charge air to be supplied to the combustion engine (1). used to do

Thus, in FIG. 1 , an exhaust gas turbocharging system 2 including a plurality of exhaust gas turbochargers, namely, a first exhaust gas turbocharger 4 on the high pressure side and a second exhaust gas turbocharger 5 on the low pressure side. An internal combustion engine 1 equipped with is shown.

The exhaust gas discharged from the cylinders of the internal combustion engine 1 first flows through the high-pressure turbine 6 of the first exhaust gas turbocharger 4 and is reduced in pressure in this high-pressure turbine, and the energy obtained at this time is 1 It is used to compress charge air in the high-pressure compressor of the exhaust gas turbocharger (4).

Viewed in the flow direction of the exhaust gas, a second exhaust gas turbo charger 5 is disposed downstream of the first exhaust gas turbo charger 4, and via the second exhaust gas turbo charger, the first exhaust gas turbocharger is already installed. Exhaust gas that has flowed through the high-pressure turbine 6 of the charger 4 is guided, in short, 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 gases are continuously reduced, and the energy obtained at this time is transferred to the low-pressure compressor of the second exhaust-gas turbocharger 5, likewise for an internal combustion engine. It is used to compress the charge air to be supplied to the cylinders of (1).

The method of the present invention is not limited to two-stage supercharged engines, but can also be applied to single-stage supercharged engines, in which case the AGN system is preferably mounted upstream of the turbine.

In addition to the exhaust gas supercharging system 2 comprising two exhaust gas turbochargers 4 and 5, the internal combustion engine 1 comprises an exhaust gas aftertreatment system 3 which is an SCR exhaust gas aftertreatment system. The SCR exhaust gas aftertreatment system 3 is connected between the high-pressure turbine 6 of the first exhaust gas turbocharger 4 and the low-pressure turbine 7 of the second exhaust gas turbocharger 5, so that accordingly Exhaust gas discharged from the high-pressure turbine 6 of the first exhaust gas turbocharger 4 can firstly be guided via the SCR exhaust gas aftertreatment system 3, and then the exhaust gas is passed through the second exhaust gas. It reaches within the area of the low-pressure turbine (7) of the turbocharger (5). 1 also shows an exhaust gas supply line 8 through which the exhaust gases depart from the high pressure turbine 6 of the first exhaust gas turbocharger 4 into the reactor chamber 10. It can be guided in the direction of the SCR catalytic converter 9 being disposed. Also shown in FIG. 1 is an exhaust gas discharge line 11 , which exhausts from the SCR catalytic converter 9 in the direction of the low pressure turbine 7 of the second exhaust gas turbocharger 5 . It serves to release gas. Then, the exhaust gases depart from the low-pressure turbine 7 and flow out via line 26, in particular to the outside.

An exhaust gas supply line 8 leading to the reactor chamber 10 and thus to an SCR catalytic converter 9 positioned within the reactor chamber 10 and from the reactor chamber 10 and thus to the SCR catalytic converter 9 The exhaust gas discharge line 11 away from ) is connected via a bypass line 12 in which a blocking member 13 is integrated. When the blocking member 13 is closed, the bypass line 12 is also closed, so that exhaust gas cannot flow via the bypass line. Conversely, if the blocking member 13 is opened, the exhaust gas can flow via the bypass line 12 and, more precisely, bypass the reactor chamber 10 and thus be positioned within the reactor chamber 10. It flows bypassing the SCR catalytic converter (9).

In FIG. 2 , the flow of exhaust gas passing through the exhaust gas aftertreatment system 3 in a state in which the bypass line 12 is closed via the blocking member 13 is shown by arrows 14, and FIG. , the exhaust gas supply line 8 leads into the reactor chamber 10 by means of a downstream end 15, and the exhaust gas flows approximately 180° or nearly in the region of said end 15 of the exhaust gas supply line 8. It can be seen that the flow is deflected by 180° and the exhaust gases are guided via the SCR catalytic converter (9) after the flow deflection.

The exhaust gas supply line 8 of the exhaust gas aftertreatment system 3 is equipped with an inlet device 16 through which nitrogen oxides in the exhaust gas are removed in the area of the SCR catalytic converter 9 in a defined manner. A reducing agent, in particular ammonia or an ammonia precursor material, required for conversion to can be introduced into the exhaust gas stream.

The inlet device 16 of the exhaust gas aftertreatment system 3 is preferably an injection nozzle through which ammonia or an ammonia precursor substance is injected into the exhaust gas flow inside the exhaust gas supply line 8 . In FIG. 2 , the injection of reducing agent into the exhaust gas stream in the region of the exhaust gas supply line 8 is shown as a conical spray 17 .

The section of the exhaust gas aftertreatment system 3 located downstream of the inlet device 16 and upstream of the SCR catalytic converter 9 in the direction of exhaust gas flow is referred to as a mixing section. In particular, the exhaust gas supply line 8 provides a mixing section 18 downstream of the inlet device 16 , in which the exhaust gases can be mixed with the reducing agent upstream of the SCR catalytic converter 9 .

An exhaust gas supply line (8) runs into the reactor chamber (10) at its downstream end (15). A baffle member 19 is mounted on the downstream end 15 of the exhaust gas supply line 8, and this baffle member can be displaced relative to the downstream end 15 of the exhaust gas supply line 8.

In the preferred embodiment shown, the baffle member 19 is bidirectional relative to the end 15 of the exhaust gas supply line 8 leading into the reactor chamber 10, in particular by the pneumatically actuated cylinder 20. Displaceable linearly in the direction of arrow 25, the pneumatic actuating cylinder acts on the baffle member 19 via the piston rod 21 and extends through the wall 22 of the reactor chamber 10. has been The seal 23 seals the piston rod 21 of the pneumatic cylinder 20, which passes through the wall 22 of the reactor chamber 10.

The baffle member 19 blocks the exhaust gas supply line 8 at its downstream end 15 or opens the exhaust gas supply line at its downstream end 15. It can be displaced relative to the downstream end 15 . If the baffle member 19 blocks the exhaust gas supply line 8 at the downstream end 15, it is preferable to completely bypass the SCR catalytic converter 9 or the reactor chamber 10 accommodating the SCR catalytic converter. To guide the exhaust gas, the blocking member 13 of the bypass line 12 is opened. If the baffle member 19 opens the downstream end 15 of the exhaust gas supply line 8, the blocking member 13 of the bypass line 12 may be completely closed or at least partially opened.

If the baffle member 19 opens the downstream end 15 of the exhaust gas supply line 8, the relative position of the baffle member 19 relative to the downstream end 15 of the exhaust gas supply line 8 is particularly Depending on the exhaust gas mass flow through the supply line 8 and/or depending on the exhaust gas temperature of the exhaust gas in the exhaust gas supply line 8 and/or entering the exhaust gas flow via the inlet device 16 It depends on the amount of reducing agent used.

Through the position of the baffle element 19 relative to the downstream end 15 of the exhaust gas supply line 8 with the downstream end 15 open, in particular in the region of the baffle element 19 the exhaust gas supply line ( 8) whether the deflected exhaust gases in the region of the downstream end 15 are guided or deflected more strongly in the direction of the sections of the SCR catalytic converter 9 positioned radially inward, or the SCR positioned radially outward It can be determined whether it is more strongly guided or deflected in the direction of the sections of the catalytic converter 9 .

According to a particularly preferred embodiment of the invention, the exhaust gas supply line 8 expands in the form of a funnel in the region of its downstream end 15 to form a diffuser. As a result, the flow cross-section of the exhaust gas supply line 8 is increased in the region of the downstream end 15, especially as seen in FIG. 2, of the exhaust gas supply line 8 when viewed in the flow direction of the exhaust gas. Upstream of the downstream end 15 the flow cross section of the exhaust gas supply line can first be reduced. Thus, in FIG. 2 , the flow cross-section of the exhaust gas supply line 8 downstream of the inlet device 16 for the reducing agent, as viewed in the flow direction of the exhaust gas, is first approximately constant, then first gradually tapers, and Finally, an enlargement in the region of the downstream end 15 is shown. In this case, the enlargement of the cross section of the flow at the downstream end 15 of the exhaust gas supply line 8 is preferably greater than the section in which the exhaust gas supply line 8 first tapers upstream of the downstream end 15. (8) over a shorter section.

As already mentioned above, in a particularly preferred embodiment of the present invention it is curved at least on the side towards the downstream end 15 of the exhaust gas supply line 8 to form a flow guide for the exhaust gas, preferably in a bell shape. The baffle member 19 which becomes interacts with the downstream end 15 of the exhaust gas supply line 8 . 3 and 4, the side 24 of the baffle element 19 towards the downstream end 15 of the exhaust gas supply line 8 is closer to the radially outer section of the baffle element 19 than the baffle element. It can be seen that from the radially inner section of 19 to the downstream end 15 of the exhaust gas supply line 8 there is a smaller separation distance. Accordingly, the baffle member 19 is contracted or bent in the direction of the downstream end 15 of the exhaust gas supply line 8 against the flow direction of the exhaust gas at the center of the side 24 .

If the baffle member 19 opens the downstream end 15 of the exhaust gas supply line 8, the separation distance between the baffle member 19 and the downstream end 15 of the exhaust gas supply line 8 is In order to ensure a deflection of the exhaust gas flow in the region (19) with as little pressure loss as possible, more precisely on the condition that the pressure loss is less than 10 mbar, in particular at least 100 mm.

As already mentioned above, the baffle member 19 performs a number of tasks, more precisely depending on the exhaust gas flow and/or the exhaust gas temperature and/or the amount of reducing agent introduced into the exhaust gas flow, more precisely on the exhaust gas flow. A blocking function is performed when the downstream end 15 of the supply line 8 is blocked, and a flow guide function is performed when the downstream end 15 of the exhaust gas supply line 8 is opened. An additional function of the baffle element 19 when the downstream end 15 of the exhaust gas supply line 8 is open is that droplets of the liquid reducing agent present in the exhaust gas flow fall within the region of the SCR catalytic converter 9. To prevent reaching the liquid reducing agent, droplets of the liquid reducing agent reach the side 24 of the baffle member 19 towards the downstream end 15 of the exhaust gas supply line 8 and are collected and atomized on this side. there is. In addition, large particles, such as rust particles generated during corrosion of the exhaust gas line for example, are also crushed while being hit, so that the particles can no longer clog the AGN system.

The baffle member 19 may include a catalyst coating layer in the region of the side 24 facing the downstream end 15 of the exhaust gas supply line 8 to improve exhaust gas aftertreatment.

As best seen in FIG. 4 , the enlargement of the downstream end 15 of the exhaust gas supply line 8 and the bell-shaped contour of the side 24 of the baffle member 19 preferably continuously, or continuously, that is to say without discontinuous points.

In the case of the internal combustion engine 1 of FIG. 1 , the exhaust gas aftertreatment system 3 is positioned vertically above the exhaust gas charging system 2 . Access to the cylinders of the internal combustion engine 1 is free, but access to the exhaust gas turbochargers 4 and 5 is restricted. However, the reactor chamber 10 can be simply disassembled when maintenance work is required on the exhaust gas turbochargers 4, 5.

Unlike the fact that the exhaust gas aftertreatment system 3 is arranged vertically as shown in FIG. 1 at the top of the exhaust gas charging system 2, the exhaust gas aftertreatment system 3 next to the exhaust gas charging system 2 ) is tilted by 90° and arranged horizontally, but the length of the arrangement structure increases when arranged horizontally. However, in this case, maintenance work can be carried out without limitation on the internal combustion engine 1 and the exhaust gas charging system 2 without the need to disassemble the reactor chamber 10 .

1: internal combustion engine
2: exhaust gas supercharging system
3: Exhaust gas aftertreatment system
4: exhaust gas turbocharger
5: Exhaust gas turbocharger
6: high pressure turbine
7: low pressure turbine
8: Exhaust gas supply line
9: SCR catalytic converter
10: reactor chamber
11: Exhaust gas discharge line
12: bypass line
13: blocking member
14: exhaust gas guide
15: end
16: inlet device
17: conical spray
18: Mixing section
19: baffle member
20: pneumatic cylinder
21: piston rod
22: wall part
23: sealing
24: side
25: displacement direction
26: line

Claims (15)

After the exhaust gas of an internal combustion engine comprising an SCR catalytic converter (9), an exhaust gas supply line (8) leading to the SCR catalytic converter (9) and an exhaust gas discharge line (11) leading away from the SCR catalytic converter (9) In the processing system 3,
The exhaust gas supply line 8 leads at its downstream end 15 into a reactor chamber 10 containing an SCR catalytic converter 9, with respect to the downstream end 15 of the exhaust gas supply line 8. An exhaust gas aftertreatment system for an internal combustion engine, characterized in that a relatively displaceable baffle member (19) interacts with the downstream end (15) of the exhaust gas supply line (8). The method of claim 1, comprising: an SCR catalytic converter (9); an exhaust gas supply line (8) leading to the SCR catalytic converter (9); an exhaust gas discharge line 11 away from the SCR catalytic converter 9; an inlet device 16 mounted on the exhaust gas supply line 8 to introduce a reducing agent into the exhaust gas; After the SCR exhaust gas comprising a mixing section 18 provided by the exhaust gas supply line 8 downstream of the inlet device 16 and mixing the exhaust gas with the reducing agent upstream of the SCR catalytic converter 9 An exhaust gas aftertreatment system of an internal combustion engine, characterized in that the treatment system. The method according to claim 1 or 2, wherein the baffle member (19) blocks the exhaust gas supply line (8) at its downstream end (15) or disconnects the exhaust gas supply line (8) at its downstream end. An exhaust gas aftertreatment system for an internal combustion engine, characterized in that it can be displaced relative to the downstream end (15) of the exhaust gas supply line (8) to open at (15). 4. The method according to claim 3, wherein the relative position of the baffle member (19) with respect to the downstream end (15) of the exhaust gas supply line (8) when the exhaust gas supply line (8) is open is An exhaust gas aftertreatment system for an internal combustion engine, characterized in that it is determined according to the exhaust gas temperature, or according to the amount of reducing agent introduced into the exhaust gas mass flow. 3. The exhaust gas of an internal combustion engine according to claim 1 or 2, characterized in that the baffle member (19) is linearly displaceable relative to the downstream end (15) of the exhaust gas supply line (8). post-processing system. 3. The method according to claim 1 or 2, wherein the baffle member (19) is displaceable relative to the downstream end (15) of the exhaust gas supply line (8) via a pneumatically actuated cylinder (20, 21). Exhaust gas after-treatment system of an internal combustion engine characterized by. 3. An exhaust gas aftertreatment system for an internal combustion engine according to claim 1 or 2, characterized in that the downstream end (15) of the exhaust gas supply line (8) is enlarged in a funnel shape to form a diffusion portion. 3. The baffle member according to claim 1 or 2, wherein the baffle member (19) faces the downstream end (15) of the exhaust gas supply line (8) and is curved on the side (24) where the exhaust gas flow and the reducing agent strike, An exhaust gas aftertreatment system for an internal combustion engine, characterized in that it forms a flow guide surface. 9. The baffle member (19) of claim 8, on the side (24) towards the downstream end (15) of the exhaust gas supply line (8), in a radially outer section of the baffle member (19). exhaust gas aftertreatment of an internal combustion engine, characterized in that the separation distance from the radially inner section of the baffle member (19) to the downstream end (15) of the exhaust gas supply line (8) is smaller than system. 9. The exhaust gas aftertreatment of an internal combustion engine according to claim 8, characterized in that the baffle member (19) is bell-shaped on the side (24) towards the downstream end (15) of the exhaust gas supply line (8). system. 3. The method according to claim 1 or 2, wherein between the exhaust gas supply line (8) and the exhaust gas discharge line (11) there is an SCR catalytic converter (9) or a bypass line (12) for the reactor chamber (10) connected, and a blocking member 13 is connected in the bypass line 12, and the position of the blocking member is the position of the baffle member 19 relative to the downstream end 15 of the exhaust gas supply line 8. An exhaust gas aftertreatment system of an internal combustion engine, characterized in that the relative position is determined. 3. An exhaust gas aftertreatment system for an internal combustion engine according to claim 1 or 2, characterized in that the baffle member (19) has a catalyst coating layer. An internal combustion engine (1) equipped with an exhaust gas aftertreatment system (3) according to claim 1 or 2. 14. The internal combustion engine according to claim 13, comprising a first exhaust gas turbocharger (4) with a high pressure turbine (6) and a second exhaust gas turbocharger (5) with a low pressure turbine (7). An internal combustion engine, characterized in that it is equipped with a multi-stage exhaust gas charging system (2), wherein the exhaust gas aftertreatment system (3) is connected between the high-pressure turbine (6) and the low-pressure turbine (7). 14. Internal combustion engine according to claim 13, characterized in that the engine is equipped with a one-stage exhaust gas charging system (2), the exhaust gas aftertreatment system (3) being connected upstream of the turbine.

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