WO2023117453A1

WO2023117453A1 - Device for treating exhaust gas iii

Info

Publication number: WO2023117453A1
Application number: PCT/EP2022/084944
Authority: WO
Inventors: Rafal Wróbel; Peter Räsch; Volker GRÜNIG; Markus Schuster
Original assignee: Tenneco Gmbh
Priority date: 2021-12-23
Filing date: 2022-12-08
Publication date: 2023-06-29

Abstract

The invention relates to a device (1) for conducting and treating an exhaust gas flow, comprising an outer housing (2), an inlet tube (10) which adjoins the outer housing (2), an outlet tube (11) which adjoins the outer housing (2), a flow channel K which is arranged in the outer housing (2), conducts the exhaust gas flow, and comprises a channel wall and multiple channel sections that connect the inlet tube (10) to the outlet tube (11), a first SCR catalytic converter unit (31) which is integrated into the flow channel K, a second SCR catalytic converter unit (32) which is arranged downstream of the first SCR catalytic converter unit (31) in the flow channel K, and a first opening (41) which is provided upstream of the first SCR catalytic converter unit (31) in the flow channel K for injecting an additive into the flow channel K. The thermal energy introduced into the outer housing from the exhaust gas flow is to maximize the hydrolysis reaction and simultaneously save on additional energy. For this purpose, a second opening (42) is provided in the flow channel K downstream of the first SCR catalytic converter unit (31) and upstream of the second SCR catalytic converter unit (32) in order to inject an additive into the flow channel K.

Description

Exhaust Gas Treatment Device III

The invention relates to a device for conducting and treating an exhaust gas flow, having an outer housing, an inlet pipe connecting to the outer housing and an outlet pipe connecting to the outer housing, and a flow channel with a channel wall and conducting the exhaust gas flow, which is arranged in the outer housing multiple duct sections connecting the inlet pipe to the outlet pipe. The device for conducting and treating an exhaust gas flow also has a first SCR catalytic converter unit and a second SCR catalytic converter unit arranged downstream of the first SCR catalytic converter unit and one provided upstream of the first SCR catalytic converter unit first opening in the outer housing for injecting additive into the flow channel.

A flow duct within the meaning of the invention is a device that directs the flow of exhaust gas and is formed by the duct walls that carry the exhaust gas and possibly also including the wall of the outer housing. The outer housing, in which the flow channel is arranged, is designed as a box. The exhaust gas flows through the flow channel in a flow direction. All components, such as the SCR catalytic converter units, are arranged in the flow channel. These duct walls are formed by walls of pipes or walls of housings and the outer housing or by other components such as substrates, etc., which guide the exhaust gas flow with inner and/or outer surfaces and which mainly direct the flow duct in a direction perpendicular to the direction of flow, but also fundamentally limit. In this case, the respective wall delimits the flow channel in relation to the respective central flow axis inwards or outwards. In the particular case of a heat transfer zone, the same wall delimits one channel section of the flow channel inwards and another channel section of the flow channel outwards. Or at least the same wall delimits a channel section of a heat transfer zone in a different direction than another channel section of the heat transfer zone. A section of the flow channel in the direction of flow is to be understood as a channel section. The direction of flow is to be understood as meaning the basic main direction of flow within the flow channel. The flow direction changes relative to the central axis of the outer casing. Other flow directions that deviate from the main flow direction are only relevant for the relevant definition of the features in question if they are explicitly referred to. Individual points arranged one after the other in the direction of flow are referred to as arranged downstream. Correspondingly, points arranged against the direction of flow are referred to as arranged upstream. Individual components are thin or single-walled sheet metal parts, especially the heat transfer zones.

In principle, the tubes and catalytic converters can have not only a round cross section but also an oval cross section or a cross section with a plurality of straight side surfaces in the form of a polygon. Each component forming the flow channel is in direct contact with the flow of exhaust gas.

Depending on the process within this device, the exhaust gas flow has a different temperature on one side of a component around which flow occurs on both sides than on the other side. The sheet metal construction enables heat to be transferred through the respective component from the hotter exhaust gas stream to the relatively colder exhaust gas stream. This heat input is not only influenced by the temperature difference from the inside to the outside and by the length of the respective section in the flow direction or the dwell time of the exhaust gas flow, but also by the flow direction. If the air flows through the inside and outside in the same direction, the temperature difference in the direction of flow decreases. If the flow is in the opposite direction, the temperature difference remains more constant. Downstream, upstream refers to the flow channel and the flow direction given in the flow channel. By definition, downstream and upstream also apply in relation to an exhaust gas particle that moves in a changing flow direction in the flow channel. The particle is, for example, at a time t1 at a position in the axial direction of a tube on the inside of the tube and at a time t2 greater than t1 at a position in the axial direction on the outside of the tube.

Channel sections arranged one inside the other are also referred to as "duct-in-duct". For the purposes of this invention, such a “duct-in-duct” construction or arrangement defines two downstream ones after the other and one next to the other Duct sections that have a common duct wall through which the heat is conducted from the warmer exhaust gas flow to the colder exhaust gas flow. The heat transferred in this way is referred to as passive heat or passive heat input. Side-by-side means essentially side-by-side in a direction perpendicular to the direction of flow. Heat is transferred directly from a hotter exhaust gas in one of the two duct sections to a cooler exhaust gas in the other duct section via the common duct wall. Means for enlarging the surface of the wall of the respective channel section are optionally also included. Monoliths such as catalytic converters or filters in the adjacent duct sections are not covered by a “duct-in-duct” arrangement, because the monolith does not enable direct heat transfer from the exhaust gas flow to the duct wall. The "duct-in-duct" arrangement serves to transfer the heat of the exhaust gas flow to the duct wall and to achieve a better reaction in the SCR catalytic converter downstream of the respective "duct-in-duct" arrangement. A monolith monolith in the respective duct section would not allow the heat transfer of the entire exhaust gas flow because the exhaust gas flow does not come into direct contact with the duct wall but only with the monolith. According to the invention, the exhaust gas flow is also conducted in the “duct-in-duct” arrangement through the duct wall and not through the monolith. According to the invention, the exhaust gas flow is also in the “duct-in-duct” arrangement. The common duct wall is preferably single-walled, but it can also be double-walled or multi-walled. For the purposes of this invention, the feature "duct-in-duct" also covers an arrangement in which the exhaust gas flow is divided from one channel to several channels, as long as the feature of a common channel wall for all channels and for the entire exhaust gas flow at the same time t is fulfilled.

Exhaust gas treatment devices with two SCR catalytic converters connected in series are known from US Pat. No. 6,444,177 B1. DE 697 04 351 T2 discloses a housing arrangement with an SCR catalytic converter unit arranged downstream or upstream of further monoliths with a position for the supply of reducing agent. Two units of monoliths are located in each other in the channel sections. However, the exhaust gas flow is conducted through the catalytic converters in these channel sections and not through the channel sections as part of the flow channel. DE 100 22 981 A1 makes no reference to a housing the theoretical arrangement of two SCR catalytic converter units arranged one after the other downstream, each with a separate supply of reducing agent.

The task is to maximize the hydrolysis reaction with the thermal energy introduced into the outer housing by the exhaust gas flow and at the same time to save additional energy. The object is achieved in that downstream of the first SCR catalytic converter unit and upstream of the second SCR catalytic converter unit, a second opening is provided in the outer housing for injecting additive into the flow channel and the flow channel has two rear channel sections with a common one rear channel wall, the two rear channel sections being arranged next to one another in a direction perpendicular to the direction of flow and one after the other in the direction of flow and forming a rear pair, the second channel section of the rear pair being arranged downstream of the first SCR catalytic converter unit. The exhaust housing in the form of a box has SCR units connected in series, in which a separate injection for reducing agent is provided for each of the two SCR units connected in series. The outer housing forms part of the flow channel, particularly in the area of the opening. By introducing the reducing agent at several positions along the flow channel, a similar effect is achieved as by lengthening the measuring section. This is because a correspondingly smaller quantity of reducing agent is introduced at each of the positions, for which the necessary flow path for uniform distribution and hydrolysis is correspondingly smaller. It is essential to the invention that the first two SCR units are arranged in an outer housing designed as a box. The box has the thermal advantage that the heat emitted via the channel walls along the entire flow channel initially ensures a relatively high temperature level for the entire exhaust gas flow in the box because it forms a thermally closed unit. This advantage outweighs the disadvantage of the limited space available in an outer housing designed as a box. What is achieved according to the invention is that there is still sufficient passive heat downstream of the first SCR catalytic converter unit to support the hydrolysis before the second SCR catalytic converter unit and not before the first SCR catalytic converter unit. This measure serves to ensure the passive supply of heat in front of the second SCR catalytic converter unit.

It can also be advantageous for this if the opening is provided in the outer housing and the outer housing forms part of the flow channel in the area of the opening. This means that no additional component is required in the outer housing to connect the injector to the flow channel.

In addition, it can advantageously be provided that a mixing tube or a mixer is provided as a static mixing element downstream of the opening and upstream of the SCR catalytic converter unit. The mixing tube forms neither a seat nor a bearing for the injector.

In order to use the transferred heat, it can also be advantageous if the flow channel has two front channel sections with a common front channel wall, the two front channel sections being arranged next to one another in a direction at right angles to a direction of flow and one after the other in the direction of flow and form a front pair as a "duct-in-duct" arrangement for passive heat supply. Such a geometry is referred to as “duct-in-duct” and serves as a heat transfer zone for heat from a hot exhaust stream to a relatively colder exhaust stream. This type of heat supply in the relatively colder exhaust gas flow is described as passive heat supply. On the contrary, an active supply of heat within the meaning of this invention is described with the aid of an additional device for generating thermal energy, such as a burner.

It is essential that the flow duct has two further rear duct sections forming a rear pair with a common rear duct wall, the two rear duct sections being arranged next to one another in a direction at right angles to a direction of flow in the flow duct and one after the other in the direction of flow downstream a "duct in-duct” arrangement for a passive supply of heat. The sequential double heat exchange within the exhaust gas flow makes it possible to improve the passive heat supply in the flow channel and at the same time over the entire length of the Flow channel to achieve a relatively balanced, but also sufficiently high temperature for the hydrolysis reaction.

According to the invention, the exhaust gas housing in the form of a box has two “duct-in-duct” zones that function independently of one another and are connected in series as a system, in each of which a “duct-in-duct” arrangement is provided. The sequential double heat exchange within the exhaust gas flow makes it possible to improve the passive heat supply in the flow channel and at the same time to achieve a relatively balanced temperature that is also sufficiently high for the hydrolysis reaction over the entire length of the flow channel. It was determined that a sufficiently high temperature can be guaranteed in the second "duct-in-duct" zone if the maximum possible temperature in the first "duct-in-duct" zone is only that for a reaction necessary heat exchange is realized. Due to the geometry of the box, sufficient heat remains for the second “duct-in-duct” zone. The geometry of the outer housing as a box is essential because the box forms a thermally closed unit in which the heat is basically retained and distributed via the flow channel. Sufficiently high temperatures are reached in the box in important operating states of the internal combustion engine in order to supply all of the reactants introduced to a hydrolysis reaction and to ensure the downstream reaction with individual components of the exhaust gas. The separation of the two channel sections of the respective "duct-in-duct" zone by only one and preferably simple or single-walled channel wall enables optimal heat exchange in the heat transfer zone, in which the heat energy can be conducted through the channel wall quickly and with little loss .

In connection with the design and arrangement according to the invention, it can be advantageous if all channel sections are arranged one after the other in the direction of flow. The channel sections are arranged in such a way that each theoretical flow particle of the exhaust gas flow in the flow channel flows through all channel sections. It is not provided that the exhaust gas flow is divided into several channel sections. According to the invention, it is essential that the directions of flow are opposite in the two front channel sections and in the same direction in the two rear channel sections. The different selection of the relative flow directions can influence the temperature differences that occur along the respective channel section between the hot exhaust gas flow and the cold exhaust gas flow. In this way, the amount of heat to be exchanged can be evenly distributed over both “duct-in-duct” zones or both pairs of duct sections.

With regard to insufficient heat due to critical operating parameters in the system, it can be advantageous for a device for active heat supply into the flow channel to be provided. The device for generating thermal energy is arranged on the exhaust gas housing in the form of a box and is designed in such a way that the thermal energy is introduced in front of the first SCR unit and in front of the second SCR unit at the same time.

With regard to separately introduced active thermal energy, it can be of particular importance for the present invention if the flow channel has two further upper channel sections with a common upper channel wall, with the two upper channel sections running in a direction perpendicular to a flow direction are arranged side by side and sequentially in the flow direction and form an upper pair. This makes it possible to use the separate active heat supply twice, namely once in the channel in which it is introduced and a second time on the indirectly heated outside of this channel wall. The exhaust gas flow inside the two upper channels can be heated a first time directly by the hot gas from a burner or by an electrical heat source and fed to a first hydrolysis reaction. The channel wall of the corresponding upper section of the flow channel into which the active heat is introduced is also heated as a result. The heat of these heated channel walls is carried away via the channel walls to the outside from the inner flow channel to the other outer side of the channel wall to the outer flow channel. According to the invention, the heat is tapped off there a second time further downstream by the exhaust gas flow, which is then fed to a second hydrolysis reaction. It can also be advantageous if the first channel section of the rear pair is upstream of the first SCR catalytic converter unit. The exhaust gas flow is still relatively hot upstream of the first SCR catalytic converter unit. This ensures that there is still sufficient passive heat downstream of the first SCR catalytic converter unit to support the hydrolysis before the second SCR catalytic converter unit and not before the first SCR catalytic converter unit.

It can also be advantageous if the first channel section of the upper pair is arranged upstream of the first channel section of the front pair and the second channel section of the upper pair is arranged downstream of the first SCR catalytic converter unit. This also ensures that there is still sufficient passive heat downstream of the first SCR catalytic converter unit to support the hydrolysis before the second SCR catalytic converter unit and not before the first SCR catalytic converter unit. This measure also serves to better distribute the passive supply of heat in the flow channel.

It can be advantageous here if the second channel section of the upper pair is arranged upstream of the second channel section of the rear pair. As a result, a third measure ensures that there is still sufficient passive heat downstream of the first SCR catalytic converter unit to support the hydrolysis before the second SCR catalytic converter unit and not before the first SCR catalytic converter unit. This also means that the passive supply of heat in the flow channel is better distributed.

Finally, it can be advantageous if an opening is provided in the flow channel for injecting additive into the flow channel upstream of the SCR catalytic converter unit. Access to the respective SCR catalytic converter unit through the outer housing into the flow channel is to be provided regardless of whether the outer housing forms part of the flow channel or is limited in the area of the opening of the flow channel, for example by the mixing tube.

With regard to the longest possible flow channel, it is advantageous if the flow channel upstream is constructed in such a way that the flow channel deflects or folds the exhaust gas flow four to eight times, preferably six times by 180°. The Folding or deflection takes place in the area or in the direction of the end faces of the outer housing, so that the main direction of flow runs essentially along the central axis in both directions and the change in direction is given by the folding or deflection

The location designations “front”, “back” and “top” only serve to clearly differentiate the components. With regard to the function and the interaction according to the invention, the geometric position of the components is not important.

Further advantageous features are listed below, which are also shown in the figures in a special embodiment, but are not limited to these embodiments:

- the additive is injected through the first port in a direction opposite to the direction in which the additive is injected through the second port;

one or more injectors or a receptacle for one or more injectors or more openings in the area of the respective injection point are provided at the respective opening;

- The flow channel connects the central tube to the first jacket tube and the first jacket tube to the first SCR catalytic converter unit;

- The flow channel connects the first SCR catalytic converter unit with the second jacket tube;

- The first jacket tube is arranged upstream and the second jacket tube downstream of the first SCR catalytic converter unit;

- the second SCR catalytic converter unit is arranged downstream of the second jacket tube; the intermediate housing is coupled to a device for active heat supply; - A filter unit with a filter body and a filter housing is provided in the flow channel between the central tube and the first opening, the filter housing forming part of the flow channel;

- Between 8 and 12, preferably 9 channel sections are provided, which are arranged straight and parallel to one another and one after the other in the direction of flow and which are each separated by a curve section which deflects the exhaust gas flow by at least 90°.

Further advantages and details of the invention are explained in the patent claims and in the description and shown in the figures of a special embodiment. Show it:

FIG. 1 shows a stylized sectional view of a device with an outer housing in the form of a box;

FIG. 2 shows an enlarged view of a central tube with two casing tubes and collars at the ends;

Figure 3-5 sectional views A-C according to Figure 1;

Figure 6-8 Schematic sketches of the exhaust gas treatment;

Figure 9-10 representations of two inner housings.

As shown in FIG. 1, a device 1 for guiding and treating an exhaust gas flow has an outer housing 2 in the form of a box. The exhaust gas flow is introduced into the outer housing 2 via an inlet pipe 10 and discharged via an outlet pipe 11 . The inlet pipe 10 and the outlet pipe 11 each connect to the outer housing 2 . A flow channel K is arranged in the outer housing 2 , which conducts the flow of exhaust gas and which connects the inlet pipe 10 to the outlet pipe 11 . The flow channel K or the channel wall of the flow channel K is formed by different components, such as tubes, housing in the outer housing 2 and the outer housing 2 itself. According to FIG. components arranged one after the other in direction S: connecting pipe 29, Channel segment 27 consisting of intermediate housing 28 and connecting pipe 29, central pipe 20, baffle plate 23, filter unit 6, outer housing 2, first mixing pipe 25, inner housing 50, first casing pipe 21, collar 203, first SCR catalytic converter unit 31, outer housing 2, second mixing pipe 26 , inner housing 51, second jacket tube 22, collar 204, second SCR catalytic converter unit 32, outer housing 2 and tube 30. The outer housing 2 forms different sections of the flow channel K with various parts of the housing wall that are not specified in detail.

The device 1 is constructed partially symmetrically to a central Z axis. The central tube 20, the two jacket tubes 21, 22, the filter unit 6 and the intermediate housing 28 are also arranged coaxially to the central axis Z, as is a separate device 7 for supplying fuel, which is attached to the outer housing 2 from the outside . Each of the two SCR catalytic converter units 31, 32 comprises four catalytic converters 31a-d, 32a-d, which are positioned circumferentially around the central axis Z, symmetrically offset by 90° in each case according to the sectional view A-A according to FIG. Several shelves are provided in the outer housing 2 for storing the components. Shelves 241, 242 are shown as examples.

In the flow channel K, a total of three heat transfer zones are provided for transferring heat from a hot exhaust gas stream to an exhaust gas stream that is colder relative to the hot exhaust gas stream. The heat transfer zones are specially designed as “duct-in-duct”. Using the front heat transfer zone as an example, the “duct-in-duct” arrangement comprises two channel sections K1a, K1b with a common front channel wall KW1. The channel section K1a is formed by a front part of the central tube 20 . The channel section K1b is bounded on the inside by the outer front part of the central tube 20 and bounded on the outside by the inside of the first casing tube 21 . The two channel sections K1a, K1b are separated from one another by the central tube 20 and thus by a common channel wall KW1. The two channel sections K1a, K1b are arranged next to one another in a direction perpendicular to a direction of flow S, in this case in a radial direction to the central axis Z. In addition, the two duct sections K1a, K1b are arranged one after the other in the flow direction S such that after the first duct section K1a, the exhaust gas flow first flows through other components of the flow duct K before it flows through the second duct section K1b. This The two front channel sections K1a, K1b form a front pair P1 of channel sections.

A second and rear pair P2 of channel sections K2a, K2b, which form a rear heat transfer zone according to the "duct-in-duct" principle, includes the rear part of the central tube 20 and the second jacket tube 22. Here, too, the central tube 20 delimits the channel section K2a to the outside and the channel section K2b to the inside. The second jacket tube 22 delimits the channel section K2b to the outside. This arrangement results in the adjacent geometry arranged at right angles to the flow direction S with only one common channel wall KW2. After the channel section K2a, further components of the flow channel K are also initially flowed through in the rear pair before the second channel section K2b is flowed through.

The third heat transfer zone with a common channel wall KW3 is formed by the upper pair P3 of channel sections K3a, K3b. The duct section K3a is formed by the duct segment 27, which includes the connecting pipe 29 and the intermediate housing 28 and which outwardly delimits the duct section K3a and forms the common duct wall KW3. The channel section K3b is bounded on the inside by the connecting pipe 29 and the intermediate housing 28. On the outside, essentially the inside of the outer housing 2 forms the boundary for the channel section K3b.

In addition, two SCR catalytic converter units 31, 32 are provided and upstream of each SCR catalytic converter unit 31, 32 there is an injector 41a, 42a for injecting additive.

The type of heat transfer in the heat transfer zones to the relatively colder exhaust gas stream is described as passive heat input. In contrast to this, an active supply of heat into the exhaust gas flow is achieved with the aid of the additional device 7 arranged on the outer housing 2 for generating thermal energy. For this purpose, a flame tube 70 is provided in the intermediate housing 28, through which the exhaust gas stream flows. The hot exhaust gas stream flows through the upper channel section K3a, the front channel section K1a and K1a in immediate succession the rear channel section K2a. The first passive heat exchange occurs in the front pair P1 in the front, outer channel section K1b in the first jacket tube 21 after the exhaust gas flow has been supplied with reducing agent via an injector 41a and before it flows into the first SCR catalytic converter unit 31 . The rear, outer channel section K2b is then provided in order to again passively heat the exhaust gas flow after the supply of reducing agent with an injector 42a, before it flows into the second SCR catalytic converter unit 32. The upper, outer channel section K3b makes it possible to additionally supply the exhaust gas flow with passive heat at the point at which heat is actively supplied to the exhaust gas flow with the aid of the device 7 . The active heat is supplied in the upper channel section K3a and passively transferred to the exhaust gas flow in the upper channel section K3b via the common channel wall KW3. The third pair also ensures that the exhaust gas flow is supplied with passive heat a second time before the second treatment with reducing agent and after a correspondingly long flow path. The first time before the second injector 42a before the mixing tube 26 and the second time after the second mixing tube 26 immediately before the second SCR catalytic converter unit 32.

With this architecture it is achieved that the heat transfer is carried out in the three "duct-in-duct" heat transfer zones one after the other. A theoretical flow particle is only fed to the rear heat transfer when the front heat transfer is complete. Correspondingly, the upper heat transfer only takes place when the rear heat transfer is complete. Another significant aspect of the architecture is that the exhaust gas flow is folded a total of six times, i.e. deflected by 180°. A decisive component for this is the collar 203, 204, which is arranged at the end of the central tube 20 and is shown clearly in FIG -d, 32a-d flows in. The collar 203, 204 deflects the exhaust gas stream flowing out of the jacket pipe 21, 22 by 180° with its outer side 203a, 204a. The collar 203 forms on the inlet side 201 with its inside 203i a funnel for the exhaust gas flowing into the central tube 20 and the collar 204 forms on the outlet side 202 with its inside 204i a diffuser for the exhaust gas flowing out of the central tube 20. The numerous flow paths are also illustrated in FIGS. 3-5, which each show a section in a plane as can be seen in FIG. The openings shown are, insofar as they do not have reference numbers, openings in one of the intermediate bases that are not described in detail. FIG. 3, a section AA through the rear heat transfer zone, shows the four catalytic converters 32a-d, which are arranged around the central tube 20 and the second casing tube 22. The first mixing tube 25 is shown in section in the upper area. In the lower area, the pipe 30 can be seen in alignment, which collects the flow of exhaust gas in the outer housing 2 and leads it into the outlet pipe 11 . Section BB is in an intermediate floor 241 directly in front of the four catalytic converters 32a-d. In the upper area, the exhaust gas stream flows out of the first mixing tube 25 into the inner housing 50. In the lower area, the exhaust gas flows out of the inner housing 51 into the second jacket tube 22. Another part of the exhaust gas stream also flows out of the catalytic converters 32a-d and finds its way through several openings in the intermediate floor downwards to the pipe 30. After section CC, the exhaust gas flow moves out of the connecting pipe 29 into the intermediate housing 28 according to FIG is arranged to the central tube 20. The exhaust gas flow emerging from the catalytic converters 31a-d, not shown in this section, finds its way through unspecified openings in an intermediate floor to the second mixing tube 26. A baffle plate 23 is provided downstream of the central tube 20, through which the exhaust gas flow is distributed to in turn downstream provided filter body 60 of the filter unit 6 takes place, which is mounted in a filter housing 61.

Various simplified models for the passive and active supply of heat are shown in FIGS. 6 to 8, which can be realized with the concrete geometry of a box described above. For a better overview, the outer housing, inlet pipe, outlet pipe, duct segment and intermediate housing as well as other components are not shown on these models. According to FIG. 6, the still relatively hot exhaust gas flows into the central pipe 20 and after injection with the first injector 41a with reducing agent in the front “duct-in-duct” arrangement through the common front duct wall KW1 for the first time in the first Casing tube 21 is passively heated before it enters the first SCR catalytic converter unit 31 flows in. The second injection then takes place with the injector 42a in the second mixing tube 26 and the second passive heating in the rear "duct-in-duct" arrangement through the second common duct wall KW2 before it flows through the second SCR catalytic converter unit 32 . In addition to the passive heating, according to FIG. 7, active heat is supplied to the exhaust gas flow via the device 7 immediately after it has flowed into the box. The other possibility of tapping passive heat from the actively heated exhaust gas flow via a "duct-in-duct" arrangement is shown in FIG absorbs passive heat.

The core of the box geometry, as shown in FIGS. 1 to 5, is formed by the two inner housings 50, 51, which are shown in FIGS. 9 and 10. The respective inner housing 50, 51 connects the mixing tube 25, 26 to the casing tube 21, 22, on which the catalytic converters 32a-32d are arranged downstream. The design of the two inner housings 50, 51 encompassing the jacket tube 21, 22 makes it possible to arrange the two housings around the jacket tube 21, 22 next to one another and at the same time to have two exhaust gas flows independently of one another and in opposite directions in the direction of the central axis Z to lead the outer housing 2.

The respective inner housing 50, 51 is arranged around the central axis Z and encloses a volume which connects the mixing tube 25, 26 in its function as an inlet connection and the jacket tube 21, 22 in its function as an outlet connection. The inner housing delimits a separate or dedicated volume, which is completely independent of the outer housing. The inlet port 25, 26 is parallel and acentric to the central axis Z and the outlet port 21, 22 relative to the inner housing 50, 51 and in the axial direction of the central axis Z opposite to the inlet port zen 25, 26 and coaxial with the central axis Z . The inner housing 50, 51 is combined with the central tube 20 in such a way that the central tube 20 completely penetrates the inner housing 50, 51, with the inner housing 50, 51 being sealed off from the central tube 20. Two identical inner housings 50, 51 positioned next to one another in the radial direction to the central axis Z form a point-symmetrical overall housing G with two separate chambers, the overall housing G having a contour running around the same central axis Z for attachment in one Outer housing 2 has. The inner housings 51, 52 each have the same outer contour on the edge side, which, when combined to form the overall housing G, results in an outer collar 52 that runs around the central axis Z in a circular, elliptical or continuous manner. The outer housing 2 has an intermediate base 242 into which the inner housings 50, 51 are inserted. The inner housing 50, 51 has a volume-limiting semi-circular contour which runs around the outlet socket 21, 22 and is concentric with the central axis Z. The geometry of an individual intermediate housing 50 is shown in more detail in FIG.

Claims

Device (1) for guiding and treating an exhaust gas flow with a) an outer housing (2) and an inlet pipe (10) adjoining the outer housing (2) and an outlet pipe (11) adjoining the outer housing (2). , b) a flow channel (K) arranged in the outer housing (2) and guiding the flow of exhaust gas, having a channel wall and having a plurality of channel sections, which connects the inlet pipe (10) to the outlet pipe (11), c) one integrated into the flow channel (K). first SCR catalytic converter unit (31) and a second SCR catalytic converter unit (32) arranged downstream of the first SCR catalytic converter unit (31) in the flow channel (K), d) one upstream of the first SCR catalytic converter unit ( 31) provided first opening (41) in the flow channel (K) for injecting additive into the flow channel (K), characterized in that e) downstream of the first SCR catalytic converter unit (31) and upstream of the second SCR Catalyst unit (32) a second opening (42) is provided in the flow channel (K) for injecting additive into the flow channel (K), f) the flow channel (K) having two rear channel sections (K2a/b) with a ner common rear channel wall (KW2), the two rear channel sections (K2a/b) being arranged next to one another in a direction at right angles to the direction of flow (S) and one after the other in the direction of flow (S) and a rear pair (P2) form as a “duct-in-duct” arrangement for passive heat supply and g) the second channel section (K2b) of the rear pair (P2) is arranged downstream of the first SCR catalytic converter unit (31). Device (1) according to claim 1, characterized in that the opening (41, 42) is provided in the outer housing (2) and the outer housing (2) in the region of the opening (41, 42) forms part of the flow channel (K). Device (1) according to one of claims 1 or 2, characterized in that downstream of the opening (41, 42) and upstream of the SCR catalytic converter unit (31, 32) a mixing tube (25, 26) or a mixer as a static mixing element is provided. Device (1) according to one of the preceding claims, characterized in that the flow channel (K) has two front channel sections (K1a/b) with a common front channel wall (KW1), the two channel sections (K1a/b) are arranged next to one another in a direction perpendicular to a direction of flow (S) in this flow channel (K) and one after the other in the direction of flow (S) and a front pair (P1) as a "duct-in-duct" arrangement for passive heat supply form. Device (1) according to one of the preceding claims, characterized in that a device (7) for an active supply of heat in the flow channel (K) is provided. Device (1) according to one of the preceding claims, characterized in that the flow channel (K) has two further upper channel sections (K3a/b) with a common upper channel wall (KW3), the two upper channel sections (K3a/b) are arranged side by side in a direction perpendicular to a flow direction and sequentially in the flow direction (S) to form an upper pair (P3). Device (1) according to one of the preceding claims, characterized in that the first channel section (K2a) of the rear pair (P2) is arranged upstream of the first SCR catalytic converter unit (31). Device (1) according to claim 6 or 7, characterized in that the first channel section (K3a) of the upper pair (P3) upstream of the first channel section (K1 a) of the front pair (P1) and the second channel section (K3b) of the upper pair (P3) is arranged downstream of the first SCR catalytic converter unit (31). Device (1) according to one of claims 6 to 8, characterized in that the second channel section (K3b) of the upper pair (P3) is arranged upstream of the second channel section (K2b) of the rear pair (P2). Device (1) according to one of the preceding claims, characterized in that the two openings (41, 42) in relation to a central axis (Z) opposite on the outer housing (2) and / or offset in the radial direction on the outer housing (2) are arranged. Device (1) according to one of the preceding claims 8 to 11, characterized in that in the direction of flow (S) between each two of the following components, the front pair (P1) and between each two of the following components each rear pair (P2) is arranged : first opening (41) first mixing pipe (25) first SCR catalytic converter unit (31) second opening (42) second mixing pipe (26) second SCR catalytic converter unit (32). Device (1) according to any one of the preceding claims, characterized in that the flow channel (K) is constructed such that the flow channel (K) the exhaust gas flow four to eight times, preferably six times

180° deflects or folds.

Device (1) according to one of the preceding claims, characterized in that the front pair (P1) is arranged by a central tube (20) and a first jacket tube (21 ) is formed, wherein a first part of the central tube (20) forms the common front channel wall (KW1), the central tube (20) is arranged coaxially to the central axis (Z) and the rear pair (P2) through the central tube (20) and a second casing tube (22) arranged around the central tube (20) or coaxially to the central tube (20) and a second part of the central tube (20) forming the common rear channel wall (KW2). System consisting of a device for treating exhaust gas according to one of the preceding claims and an exhaust system for an internal combustion engine, wherein the exhaust system comprises a manifold system, a system with an oxidation catalyst, a pipe system and a silencer system and sensors.