Title of Invention	"PROCESS AND DEVICE FOR TREATING EXHAUST FUMES FROM AN INTERNAL COMBUSTION ENGINE"
Abstract	The claimed process for treating exhaust fumes (6) from an internal combustion engine (19) in at least two modules (3, 4, 5, 17) is designed in such a way that an exhaust fume stream can be at least in part deflected depending on a load state of the internal combustion engine (19) in such a way that at least parts of the exhaust fumes (6) flow through one or more modules (3, 4, 5, 17). The claimed process and the claimed device (1) make it possible to design and operate in an advantageous manner even the exhaust fume system of large-volume internal combustion engines (19), conversion and treatment of the exhaust fumes (6) being carried out in individual modules (5, 3, 4, 17) even in no-load operation, basically at very low exhaust fume mass flow rates. The individual modules (3, 4, 5, 17) can be adapted to various load levels of the internal combustion engine (19).

Title of Invention

"PROCESS AND DEVICE FOR TREATING EXHAUST FUMES FROM AN INTERNAL COMBUSTION ENGINE"

Abstract

The claimed process for treating exhaust fumes (6) from an internal combustion engine (19) in at least two modules (3, 4, 5, 17) is designed in such a way that an exhaust fume stream can be at least in part deflected depending on a load state of the internal combustion engine (19) in such a way that at least parts of the exhaust fumes (6) flow through one or more modules (3, 4, 5, 17). The claimed process and the claimed device (1) make it possible to design and operate in an advantageous manner even the exhaust fume system of large-volume internal combustion engines (19), conversion and treatment of the exhaust fumes (6) being carried out in individual modules (5, 3, 4, 17) even in no-load operation, basically at very low exhaust fume mass flow rates. The individual modules (3, 4, 5, 17) can be adapted to various load levels of the internal combustion engine (19).

Full Text	Process and apparatus for treating an exhaust gas from an internal combustion engine The present invention relates to a process and an apparatus for treating an exhaust gas from an internal combustion engine. A particularly preferred application area for the present invention is its use for treating an exhaust gas from large-volume internal combustion engines, in particular diesel engines, in particular in locomotives and water-borne vehicles. The exhaust gases from internal combustion engines contain undesirable substances, the levels of which in the exhaust gas must in many countries be below statutory emission limits. This includes the concentration of particulates in the exhaust gas, which in many countries must not exceed specific levels. However, in particular in the case of large-volume internal combustion engines, it is in some cases difficult to comply with these emission limits in particular under idling conditions. Consequently, the present invention is based on the object of providing a process and an apparatus by means of which the emission of undesirable substances can be reliably reduced even for large-volume internal combustion engines. The object is achieved by a process and an apparatus having the features of the independent claims; the dependent claims relate to advantageous refinements. The process according to the invention for treating an exhaust gas from an internal combustion engine, characterized in that at least two modules are formed for treating the exhaust gas, is based on the fact that an exhaust-gas stream can be diverted at least in part as a function of a loading state of the internal combustion engine in such a way that at least parts of the exhaust gas flow through one or more modules. In this context, the term exhaust-gas treatment is to be understood in particular as meaning a reduction in the concentration of at least one component in the exhaust gas. In the present context, exhaust-gas treatment is preferably also understood as meaning a reduction in the level of particulates in the exhaust gas. The loading state of the internal combustion engine has an effect in particular on the following exhaust-gas variables: temperature, exhaust-gas mass flow, pollutant concentration and/or mean exhaust-gas velocity. It is often the case that only a very small number of load points, for example an idling load point, a partial load point and a full load point, occur especially in large-capacity internal combustion engines, in particular corresponding diesel engines, which are used in railcars, for example locomotives, water-borne vehicles, for example ships and/or boats, and in stationary operation. By suitably configuring the modules and suitably adopting a procedure, it is in this way possible to effect an exhaust-gas treatment that is accurately matched to the abovementioned load points. For example, all the modules can be formed as an idling module which is adapted to the exhaust-gas situation in idling mode and is therefore suitable for treating the exhaust gas under idling conditions. By suitably controlling the connecting means, it is possible to divert the exhaust-gas stream in such a way that a total exhaust-gas stream is applied substantially equally to at least two modules. A total exhaust-gas stream is to be understood in particular as meaning an exhaust-gas stream, in particular an exhaust-gas mass or volumetric flow, which is integrated and/or cumulative over the time for which it flows through the corresponding module. This leads to a substantially equal flow through the modules. In particular if each module comprises at least one particulate filter for reducing the particulate content in the exhaust gas, uniform loading and if appropriate also a uniformly changing pressure loss is advantageously achieved. A first module may be formed in such a way that it alone or in combination with a further module is adapted to the exhaust-gas situation at the partial load point, while a second module may be formed in such a way that it, in conjunction with a further module and the first module, is adapted to the exhaust-gas situation at the full load point. In this way, a modular structure and a suitable diversion of the exhaust gas can in each case lead to optimum conversion of the exhaust gas at the various load points. A module generally comprises at least one honeycomb body which comprises cavities, for example passages, through which an exhaust gas can flow. A honeycomb body may in particular comprise a ceramic and/or a metallic honeycomb body. A ceramic honeycomb body can be produced as an extruded monolith, while a metallic honeycomb body may comprise at least one at least partially structured layer, which has in particular been deformed in such a way as to form cavities through which an exhaust gas can flow. This deformation is to be understood in particular as meaning winding or twisting of at least one stack composed of at least one metallic layer. It is in this case also possible to use substantially smooth layers which together with the structures of the at least partially structured layer form the cavities. The honeycomb body may also comprise walls which in part allow a fluid to flow through them. The honeycomb body may form or comprise a particulate filter. The effectiveness of an exhaust-gas treatment is highly dependent on the flow conditions through the corresponding module. For example, it is advantageous in particular for there to be as far as possible no laminar flows within the module, but rather for the flows as far as possible to be turbulent. It is in this way possible to effectively avoid laminar boundary flows which result in only a small part of the exhaust gas coming into contact with the walls of the cavities in the honeycomb body, which generally have a catalytically active coating. This is particularly important if an open particulate filter is included in the module, since the effectiveness of such a filter is highly dependent on a corresponding turbulent flow. In particular in the case of large-volume internal combustion engines, however, the generally large dimensions of the corresponding exhaust-gas systems as well as the low idling speed of such engines in idling mode means that the exhaust-gas mass flow is very low, resulting in low flow velocities. This leads to a relatively low Reynolds number of the flow as it flows through the modules and therefore to possibly too low a degree of turbulence. Here, the process according to the invention can lead to an increase in the Reynolds number by, as it were, reducing the total available surface area of the modules for the exhaust gas to flow through in order to be treated, thereby increasing the flow velocity and Reynolds number. By way of example, it is possible for a corresponding exhaust-gas system to comprise four modules for reducing the particulate concentration in the exhaust gas. In idling mode, the installation is operated in such a way, through suitable actuation of the connecting means, that in each case only one of four possible modules has the exhaust gas flowing through it. Although this also reduces the maximum available reaction and respectively filtration surface area, it particularly advantageously leads to an increase in the flow velocity and therefore to an increase in the Reynolds number of the flow. However, there is no disadvantage in the lower reaction and/or filter surface area, since under idling conditions in particular the level of particulates is so low that the corresponding filter or reaction surface area of the module is sufficient to achieve enough conversion and respectively filtering. In this way, even in idling mode of large-volume internal combustion engines, the exhaust gas can be effectively treated. This is advantageous since in particular in large-volume internal combustion engines there are prolonged idling or low-load phases, for example when switching locomotives are waiting for the next switch or for ship engines which for example in port are used only to supply power. As the load rises, i.e. for example as the internal combustion engine speed increases, it is possible, for example, to gradually switch further modules to have exhaust gas flowing through them. At higher engine speeds, a higher mean exhaust-gas velocity and a higher exhaust-gas mass flow are generally present, and consequently it is then advantageous for the exhaust gas to flow through a plurality of modules in order to provide a sufficiently large reaction and respectively filter surface area. According to an advantageous refinement of the process according to the invention, in each module at least a reduction in the particulate concentration of the exhaust gas flowing through the module takes place. For this purpose, a particulate filter may in particular be formed in each of the modules. The formation of further components is possible and advantageous; by way of example, a suitable oxidation catalyst on a honeycomb body may be formed upstream of the particulate filter, leading in particular to oxidation of nitrogen monoxide (NO) to nitrogen dioxide (N02) , which serves as an oxidizing agent for the carbon contained in the particulates. A particulate filter of this type is known as a continuously regenerating particulate filter (CRT, continuous regenerating trap). According to a further advantageous configuration of the process according to the invention, the reduction in the particulate concentration takes place in an open particulate filter. An open particulate filter is to be understood as meaning a particulate filter in which the exhaust gas flowing through the particulate filter does not have to flow through a wall of the particulate filter. The alternative is a closed particulate filter, in which a multiplicity of passages are formed, of which in each case some are open on the entry side and closed on the exit side, while others are closed on the entry side and open on the exit side. In this way, the exhaust-gas stream is forced to flow through the porous wall of the particulate filter, in order to pass from a passage that is open on the entry side into a passage that is open on the exit side. As the exhaust gas flows through the wall, the particulates which it contains are filtered out. Open filters are also understood as bypass flow filters in which there is no filtering of the main stream, for example by a diesel particulate filter with passages closed on alternate sides, but rather only filtering of a bypass flow. An open particulate filter therefore cannot per se become blocked. Although it is theoretically possible for the porous walls used as filter surfaces to become laden with particulates to such an extent that particulates are no longer filtered, in this case the unfiltered exhaust gases can continue to flow through the particulate filter unimpeded; by contrast, a closed filter in which the filter surfaces become blocked forms a very high back-pressure which ultimately means that exhaust gas can no longer flow through the particulate filter. In this respect, an open particulate filter can also be understood as a barrier-free particulate filter. In the case of an open particulate filter, it is particularly preferable for the filter to be composed of substantially smooth layers and at least partially corrugated layers. In particular, in this case the substantially smooth layer, at least in partial regions, may be composed of a material through which a fluid can flow and which is in particular porous, while the at least partially corrugated layer is composed for example of thin metal sheet or a thin sheet-metal foil or a thin metal foil. The corrugated layer may preferably have guide structures which are responsible for diverting the exhaust gas toward the filter regions. With regard to the configuration of these or similar guide structures, it is preferable for the structures to effect an increase in the velocity of the exhaust gas in the passage, so that in particular the proportion of the exhaust gas which remains in the open passage and flows past or along the filter surface is at a significantly increased velocity compared to the velocity of the exhaust gas when it enters the passage. Tests have shown that as the velocity of this bypass exhaust-gas stream increases the separation rate of the filter surface(s) or the particulate trap can be increased. The process according to the invention is advantageous in particular for an open particulate filter which is in each case comprised within the modules, since in this case it is ensured even at low idling speeds of in particular even large-volume internal combustion engines that the flow in the modules has a Reynolds number which during flow through the particulate filter is sufficiently high to nevertheless bring about effective removal of the particulates or conversion of the component. According to a further advantageous configuration of the process according to the invention, a diversion of the exhaust gas takes place as a function of at least one of the following variables: 4.1) a regeneration capacity of the exhaust gas for a module and 4.2) a need for regeneration of a module. In this context, a diversion of the exhaust gas is to be understood as meaning a diversion by the connecting means. A regeneration of a particulate filter comprises in particular an oxidation of the particulates held in the particulate filter. This can be effected firstly by providing an oxidizing agent, such as for example nitrogen dioxide, or as an alternative or indeed an addition for example by additional heating measures which increase the temperature of the particulate filter above a limit temperature above which the particulates are preferentially oxidized. If the exhaust gas is at a certain temperature that can lead to increased regeneration during flow through a module, it is possible to refer to a regeneration capacity of the exhaust gas as defined in 4.1) above. On the other hand, a need for reaction 4.2) of a module as referred to above, for example in the case of a particulate filter, means that the quantity of particulates that are present has exceeded a limit value above which it is advantageous to regenerate the module. In particular in a particulate filter, this may also manifest itself in a rise in the pressure loss across said particulate filter. According to a further advantageous configuration of the process according to the invention, in an idling load state the exhaust-gas stream is diverted in such a way that on average a substantially identical total exhaust-gas stream flows through substantially all the modules. In this context, a total exhaust-gas stream is to be understood as meaning the sum and/or the temporal integral of the exhaust-gas stream, preferably of the exhaust-gas mass flow or the exhaust-gas volumetric flow, over the time during which the exhaust gas flows through the module in question. The total exhaust-gas stream therefore preferably constitutes a mass, if it is the exhaust-gas mass flow that is under consideration, or a volume, if it is the exhaust-gas volumetric flow that is under consideration. In this context, in particular through-flow times of up to 5 minutes, up to 10 minutes or even of an hour or more are possible and in accordance with the invention. In principle, it is preferable here to adopt a procedure in which the flow velocity in a module, preferably in a passage of a honeycomb body that is at least part of a module, lies in the range from 10 meters per second to 25 meters per second. According to a further advantageous configuration of the process according to the invention, the number of modules through which the exhaust gas flows increases monotonically to at least one of the following variables: 6.1) exhaust-gas temperature and 6.2) exhaust-gas mass flow. It is particularly advantageous to be dependent on the exhaust-gas mass flow, since otherwise, for example if the exhaust gas is flowing through just one module, at higher loading states, in particular even at full load, flow through just one module may be disadvantageous for the effectiveness of exhaust-gas treatment. In particular if each of the modules comprises an open particulate filter, it is advantageous if the exhaust gas flows through all the modules up to the full-load state of the internal combustion engine. Regeneration of the particulate filters in question can also take place in particular during the full-load state. A further aspect of the present invention proposes an apparatus for treating an exhaust gas from an internal combustion engine, comprising an exhaust pipe, which can be connected to the internal combustion engine, and at least two modules for exhaust-gas treatment, which can be connected to the exhaust pipe, wherein at least one connecting means assigned to at least one module is formed, by which connecting means said module can be connected to the exhaust pipe in such a way that at least part of the exhaust gas can flow through said module. Each module comprises in particular a honeycomb body, which preferably comprises a corresponding catalytically active coating and/or is suitable for particulate filtering. A connecting means is to be understood in particular as meaning a component by means of which a connection to the module through which a fluid can flow can be produced or disconnected. The connecting means is preferably a correspondingly designed flap, which in the closed state can close a through-flow opening leading to the module and in the open state can open up this opening. In particular, the various connecting means can be formed in such a way that in each case only part of the exhaust gas can flow through the associated module or alternatively all of the exhaust gas can flow through the associated module. In particular in the case of the latter option, various connecting means can interact. According to an advantageous configuration of the apparatus according to the invention, the connecting means are formed in such a way that exhaust gas can flow through each module alone. Thus, the apparatus according to the invention can be operated in such a way that in particular in idling mode exhaust gas flows to a uniform extent through the individual modules, so that the individual modules are utilized equally. In particular if the modules comprise particulate filters, it is in this way possible to achieve a substantially uniform loading of the particulate filters in the modules. This leads to a substantially uniform pressure loss across the respective modules. According to a further advantageous configuration of the apparatus according to the invention, each module effects at least a reduction in the particulate concentration of the exhaust-gas stream flowing through the module. In this case, it is preferable for each module to comprise at least one particulate filter, which is particularly preferably open. For a definition of an open particulate filter, reference is made to the statements made above and to WO 02/00326 A2, the content of disclosure of which in connection with the design of the particulate filter is hereby incorporated in the present invention. According to a further advantageous configuration of the apparatus according to the invention, the connecting means comprises at least one flap. A flap constitutes a connecting means that is on the one hand simple to produce and is able to effectively produce or stop a connection to a module. Furthermore, flaps are simple to actuate and have proven stable and durable when used in exhaust-gas systems. According to a further configuration of the apparatus according to the invention, the connecting means is configured in such a way that when the exhaust gas can flow through the associated module it excludes at least one further module from the exhaust-gas flow. This can be realized in particular by a flap that has three possible positions: 1.) a first position, in which the connection to the module is closed, 2.) a second position, in which the connection to the module is open and the exhaust pipe is blocked, so that all the exhaust gas that is present at the connection to the module flows through this module, and 3.) a third position, in which exhaust gas can flow freely through both the module and the exhaust pipe. Flaps of this type can be used in particular to realize an apparatus according to the invention in which exhaust gas can flow through all the modules individually. The invention also proposes a rail-borne vehicle, preferably a railway motor car, particularly preferably a locomotive, which comprises an apparatus according to the invention or in which a process according to the invention takes place. The invention also proposes a water-borne vehicle which comprises an apparatus according to the invention or in which a process according to the invention takes place. The process and apparatus according to the invention can particularly advantageously be deployed in exhaust-gas systems of diesel engines. It is preferable for the rail-borne vehicle and the water-borne vehicle also to have a diesel engine. Furthermore, it is possible for the apparatus and process according to the invention to be used in stationary internal combustion engines, in particular diesel internal combustion engines. The advantages and details which have been disclosed in respect of the process according to the invention can also be transferred to and exploited in the same way in the apparatus according to the invention. The same also applies to the details and advantages disclosed in respect of the apparatus according to the invention, which can equally be transferred to and exploited in the process according to the invention. The apparatus according to the invention is suitable in particular for carrying out the process according to the invention. In the text which follows, the invention is to be explained in more detail with reference to the accompanying figures, without the invention being restricted to the details and advantages shown therein. In the drawing: fig. 1 diagrammatically depicts a first exemplary embodiment of an apparatus according to the invention; fig. 2 diagrammatically depicts an excerpt from a module of an apparatus according to the invention; fig. 3 diagrammatically depicts an end-on view of a module of an apparatus according to the invention; fig. 4 diagrammatically depicts a first longitudinal section through a second exemplary embodiment of an apparatus according to the invention; fig. 5 shows a second longitudinal section through the second exemplary embodiment of an apparatus according to the invention; fig. 6 shows an excerpt from an apparatus according to the invention with a connecting means in a first position; fig. 7 shows an excerpt from an apparatus according to the invention with a connecting means in a second position; and fig. 8 diagrammatically depicts an excerpt from an apparatus according to the invention with a connecting means in a third position. Fig. 1 diagrammatically depicts a first exemplary embodiment of an apparatus 1 according to the invention for treating an exhaust gas 6. Said apparatus comprises an exhaust pipe 2, a first module 3 and a second module 4 for exhaust-gas treatment. An idling module 5 is also formed. The internal combustion engine (not shown) emits an exhaust gas 6 which flows through the exhaust pipe 2 in a through-flow direction 7. The first module 3 for exhaust-gas treatment is assigned a first connecting means 8. In the present, first exemplary embodiment, said connecting means 8 comprises a pivotable flap, by means of which the module 3 can be connected to the exhaust pipe 2 in such a way that at least part of the exhaust gas 6 can flow through said module 2. A second connecting means 9 is formed in a corresponding way and is assigned to the second module 4 for exhaust-gas treatment. The idling module 5 is not assigned a connecting means, since the exhaust gas 6 flows through this idling module 5 even when the first connecting means 8 and the second connecting means 9 are in a first position preventing flow through the first module 3 and the second module 4. In particular for large-volume internal combustion engines, for example of locomotives, of water-borne vehicles, such as in particular ships or boats, and of stationary installations, it is advantageous for the idling module 5 to be adapted to the exhaust-gas situation during idling phases. By way of example, in the case of a switching locomotive, the internal combustion engine is in idling mode for a very large part of its operating time, and it is therefore useful to adapt to idling conditions. Moreover, large-volume internal combustion engines have a very low idling speed and very low flow velocities and consequently low Reynolds numbers in idling mode. If the exhaust gas 6 also in idling mode were to flow through both the idling module 5 and also the first module 3 and the second module 4 for exhaust- gas treatment, the result would be a very low Reynolds number of the exhaust-gas flow in all the modules 3, 4, 5. This would lead to more of a laminar flow, which is generally undesirable in modules for exhaust-gas treatment. If, for example, open particulate filters are comprised within the modules 3, 4, 5, however, laminar flow through these particulate filters is undesirable. Fig. 2 diagrammatically depicts an excerpt from an open particulate filter of this type. An open particulate filter of this type is formed, for example, from corrugated metallic layers 10 and substantially smooth layers 11. The substantially smooth layer 11 is formed from a material which at least in part allows a fluid to flow through it, for example a sintered porous material or a porous fiber material. Here, the corrugated metallic layer has apertures 12 which form guide vanes 13. The substantially smooth layers 11 and the corrugated metallic layers 10 form passages 14 through which the exhaust gas 6 can flow. The exhaust gas 6 follows the indicated flow lines. The apertures 12 and guide vanes 13 cause the exhaust gas 6 to be guided through the substantially smooth layer 11. The particulates 15 contained in the exhaust gas 6 accumulate in the substantially smooth layer 11. A module 3, 4, 5 may comprise at least one honeycomb body 16, as diagrammatically depicted in cross section from fig. 3. The honeycomb body 16 is in this case formed from corrugated metallic layers 10 and substantially smooth layers 11. These have been stacked to form three stacks, and these stacks are then intertwined so as to form passages 14. In addition to a particulate filter, it is also possible to form other types of honeycomb bodies. By way of example, it is possible to form honeycomb bodies 16 which support a catalytically active coating and/or are formed just from metal foils. In particular, this catalytically active coating may comprise washcoat comprising catalytically active particulates. In particular, it is also advantageous if a module 3, 4, 5 comprises an oxidation catalyst, the catalytically active centers of which catalyze at least the oxidation of nitrogen monoxide to nitrogen dioxide and comprise a corresponding open particulate filter downstream of this oxidation catalyst. The nitrogen dioxide formed in this way can then advantageously be used to regenerate the particulate filter, i.e. to oxidize the particulates 15. Both the substantially smooth layers 11 and the corrugated layers 10 may be formed from thin metal foils. It is possible to do without the formation of guide vanes 13 and apertures in particular if the honeycomb body 16 is used not as a particulate filter but rather exclusively as a support for a catalytically active coating. Fig. 4 diagrammatically depicts a second exemplary embodiment of an apparatus 1 according to the invention for exhaust-gas treatment. This apparatus 1 comprises an exhaust pipe 2, a first module 3, a second module 4, a third module 17 and a fourth module 33 for exhaust-gas treatment. An idling module is not provided here. Furthermore, a first connecting means 8, a second connecting means 9 and a third connecting means 18 are formed and assigned to the respective modules 3, 4, 17. The connecting means 8, 9, 17 therefore number one fewer than the modules 3, 4, 17, 22. The connecting means 8, 9, 17 are formed in such a way that exhaust gas can flow through each module 3, 4, 17, 22 alone. The exhaust gas emitted by an internal combustion engine 19 can in this way be advantageously diverted by means of the connecting means 8, 9, 18, as a function of a loading state of the internal combustion engine 19, in such a way that at least parts of the exhaust gas flow through one or more modules 3, 4, 17, 22 for exhaust-gas treatment. In particular, according to the second exemplary embodiment of an apparatus 1 according to the invention, it is advantageously possible in the idling state to divert the exhaust-gas stream in such a way that on average a substantially identical total exhaust-gas stream flows through all the modules 3, 4, 17, 22. Therefore, in idling mode, substantially all the modules 3, 4, 17, 22 are acted on substantially uniformly. Fig. 5 diagrammatically depicts a further longitudinal section through the second exemplary embodiment of an apparatus 1 according to the invention for treating an exhaust gas from an internal combustion engine 19. Each of the modules 3, 4, 17, 22 comprises a plurality of honeycomb bodies 16. Each of the honeycomb bodies 16 may comprise various zones. This will be explained in more detail below on the basis of the example of the honeycomb bodies 16 of the fourth module 22. Each of the honeycomb bodies 16 of the fourth module 22 comprises an oxidation catalyst zone 20 and a particulate filter zone 21. These zones 20, 21 are arranged in such a way that the exhaust gas flows firstly through the oxidation catalyst zone 20 and then through the particulate filter zone 21. Further catalyst zones are also shown in the further modules 3, 4, 17 and are formed in such a way that they are adapted to the respective loading states at which these modules 3, 4, 5, 17 are connected up. They may in particular be further oxidation catalyst zones 20, zones for conversion of nitrogen oxides and standard three-way catalyst zones. These are only examples; other catalyst zones are possible and covered by the scope of the invention. As an alternative to having a plurality of zones 20, 21 per module 3, 4, 17, 22, it is also possible for a plurality of corresponding honeycomb bodies 16 to be formed in series. In particular, the apparatus for treating an exhaust gas can be operated in such a way that the diversion of the exhaust gas effected by the connecting means 8, 9, 18 takes place as a function of the regeneration capacity of the exhaust gas 6 and a need for regeneration of a module 5, 3, 4, 17, 22. This means that when the exhaust gas satisfies certain parameters required for the regeneration of the particulate filter zones 21, for example exceeds a certain limit temperature, this exhaust gas is passed in a targeted way to a module 3, 4, 17, 22 that is in need of regeneration. This can be effected in particular by the connecting means 8, 9, 18, which are formed in such a way that, in addition to a connection of the respective modules 5, 3, 4, 17, 22, it is also possible to prevent flow through other modules. Oxidation catalyst zone 20 and particulate filter zone 21 may also be formed as individual honeycomb bodies 16 through which exhaust gas can flow in succession. Fig. 6 diagrammatically depicts an excerpt from an apparatus 1 according to the invention. Here, a connecting means 8 assigned to a first module for exhaust-gas treatment 3 is in a first position, with the result that the exhaust gas 6 from the internal combustion engine 19 does not flow through the first module 3, but rather bypasses it. Fig. 7 diagrammatically depicts the same excerpt from an apparatus according to the invention, in which the connecting means 8 has adopted a second position. This closes the exhaust pipe 2 so that the exhaust gas 6 from the internal combustion engine 19 flows through the module 3. Depending on whether further modules are also formed upstream of the first module 3, either all of the exhaust gas 6 from the internal combustion engine flows through the first module 3 or only a corresponding proportion of the exhaust gas 6 does so. The proportion in this case depends on the pressure losses in the parts of the exhaust-gas system through which the exhaust gas can flow. Fig. 8 diagrammatically depicts the connecting means 8 in a third position. Here, access to the first module 3 is open, so that a part of the exhaust gas 6 can flow through the module 3. However, a further part of the exhaust gas 6 can flow onward through the exhaust pipe 2. The distribution of the part-streams which flow through the exhaust pipe 2 and the module 3 is dependent on the pressure loss in the respective partial regions 2, 3 through which the exhaust gas is to flow. Forming the connecting means 8, 9, 18 in a corresponding or similar way to that shown in figures 6 to 8 advantageously makes it possible to implement a procedure in which exhaust gas can flow through each module individually. This in particular means that it is advantageously possible, in particular in idling mode, for each module 3, 4, 17, 22 to be fed in particular with a substantially uniform total exhaust-gas stream. The process according to the invention and the apparatus 1 according to the invention advantageously enable even the exhaust-gas systems of large-volume internal combustion engines 19 to be configured in such a way that, even in idling mode and in principle at very low exhaust-gas mass flow rates, the exhaust gas 6 is converted and treated in individual modules 5, 3, 4, 17, 22. The individual modules can be adapted to different load points of the internal combustion engine 19. List of reference numerals 1 Apparatus for treating an exhaust gas from an internal combustion engine 2 Exhaust pipe 3 First module for exhaust-gas treatment 4 Second module for exhaust-gas treatment 5 Idling module 6 Exhaust gas 7 Through-flow direction 8 First connecting means 9 Second connecting means 10 Corrugated metallic layer 11 Substantially smooth layer 12 Aperture 13 Guide vane 14 Passage 15 Particulate 16 Honeycomb body 17 Third module for exhaust-gas treatment 18 Third connecting means 19 Internal combustion engine 20 Oxidation catalyst zone 21 Particulate filter zone 22 Fourth module for exhaust-gas treatment Claims 1. A process for treating an exhaust gas (6) from an internal combustion engine (19), wherein at least two modules (3, 4, 5, 17, 22) are formed for treating the exhaust gas and characterized in that an exhaust-gas stream can be diverted at least in part as a function of a loading state of the internal combustion engine (19) in such a way that at least parts of the exhaust gas (6) flow through one or more modules (3, 4, 5, 17, 22) . 2. The process as claimed in claim 1, wherein in each module (3, 4, 5, 17, 22) at least a reduction in the particulate concentration of the exhaust gas (6) flowing through the module takes place. 3. The process as claimed in claim 2, wherein the reduction in the particulate concentration takes place in an open particulate filter. 4. The process as claimed in claim 3, wherein a diversion of the exhaust gas (6) takes place as a function of at least one of the following variables: 4.1) a regeneration capacity of the exhaust gas for a module (3, 4, 5, 17, 22) and 4.2) a need for regeneration of a module (3, 4, 5, 17, 22) . 5. The process as claimed in one of the preceding claims, wherein in an idling load state the exhaust-gas stream is diverted in such a way that on average a substantially identical total exhaust-gas stream flows through substantially all the modules (3, 4, 5, 17, 22) . 6. The process as claimed in one of the preceding claims, wherein the number of modules (3, 4, 5, 17, 22) through which the exhaust gas flows increases monotonically to at least one of the following variables: 6.1) exhaust-gas temperature and 6.2) exhaust-gas mass flow. 7. An apparatus (1) for treating an exhaust gas (6) from an internal combustion engine (19), comprising an exhaust pipe (2), which can be connected to the internal combustion engine (19), and at least two modules (3, 4, 5, 17, 22) for exhaust-gas treatment, which can be connected to the exhaust pipe (2), characterized in that at least one connecting means (8, 9, 18) assigned to at least one module (3, 4, 5, 17, 22) is formed, by which connecting means said module (3, 4, 5, 17, 22) can be connected to the exhaust pipe (2) in such a way that at least part of the exhaust gas (6) can flow through said module (3, 4, 5, 17, 22). 8. The apparatus (1) as claimed in claim 7, wherein the connecting means (8, 9, 18) are formed in such a way that exhaust gas can flow through each module (3, 4, 5, 17, 22) alone. 9. The apparatus (1) as claimed in either of claims 7 and 8, wherein each module (3, 4, 5, 17, 22) effects at least a reduction in the particulate concentration of the exhaust-gas stream flowing through the module (3, 4, 5, 17, 22) . 10. The apparatus (1) as claimed in claim 9, wherein each module (3, 4, 5, 17, 22) comprises at least one particulate filter. 11. The apparatus (1) as claimed in claim 11, characterized in that the particulate filter is open. 12. The apparatus (1) as claimed in one of claims 7 to 11, wherein the connecting means (8, 9, 18) comprises at least one flap. 13. The apparatus (1) as claimed in one of claims 7 to 12, wherein the connecting means (8, 9, 18) is configured in such a way that when the exhaust gas (6) can flow through the associated module (3, 4, 5, 17, 22) it excludes at least one further module (3, 4, 5, 17, 22) from the exhaust-gas flow. 14. A rail-borne vehicle, comprising an apparatus as claimed in one of claims 7 to 13. 15. A water-borne vehicle, comprising an apparatus as claimed in one of claims 7 to 13.

Full Text

Process and apparatus for treating an exhaust gas from an internal combustion engine
The present invention relates to a process and an apparatus for treating an exhaust gas from an internal combustion engine. A particularly preferred application area for the present invention is its use for treating an exhaust gas from large-volume internal combustion engines, in particular diesel engines, in particular in locomotives and water-borne vehicles.
The exhaust gases from internal combustion engines contain undesirable substances, the levels of which in the exhaust gas must in many countries be below statutory emission limits. This includes the concentration of particulates in the exhaust gas, which in many countries must not exceed specific levels. However, in particular in the case of large-volume internal combustion engines, it is in some cases difficult to comply with these emission limits in particular under idling conditions.
Consequently, the present invention is based on the object of providing a process and an apparatus by means of which the emission of undesirable substances can be reliably reduced even for large-volume internal combustion engines.
The object is achieved by a process and an apparatus having the features of the independent claims; the dependent claims relate to advantageous refinements.
The process according to the invention for treating an exhaust gas from an internal combustion engine, characterized in that at least two modules are formed for treating the exhaust gas, is based on the fact that an exhaust-gas stream can be diverted at least in part as a function of a loading state of the internal
combustion engine in such a way that at least parts of the exhaust gas flow through one or more modules.
In this context, the term exhaust-gas treatment is to be understood in particular as meaning a reduction in the concentration of at least one component in the exhaust gas. In the present context, exhaust-gas treatment is preferably also understood as meaning a reduction in the level of particulates in the exhaust gas. The loading state of the internal combustion engine has an effect in particular on the following exhaust-gas variables: temperature, exhaust-gas mass flow, pollutant concentration and/or mean exhaust-gas velocity. It is often the case that only a very small number of load points, for example an idling load point, a partial load point and a full load point, occur especially in large-capacity internal combustion engines, in particular corresponding diesel engines, which are used in railcars, for example locomotives, water-borne vehicles, for example ships and/or boats, and in stationary operation. By suitably configuring the modules and suitably adopting a procedure, it is in this way possible to effect an exhaust-gas treatment that is accurately matched to the abovementioned load points. For example, all the modules can be formed as an idling module which is adapted to the exhaust-gas situation in idling mode and is therefore suitable for treating the exhaust gas under idling conditions. By suitably controlling the connecting means, it is possible to divert the exhaust-gas stream in such a way that a total exhaust-gas stream is applied substantially equally to at least two modules. A total exhaust-gas stream is to be understood in particular as meaning an exhaust-gas stream, in particular an exhaust-gas mass or volumetric flow, which is integrated and/or cumulative over the time for which it flows through the corresponding module. This leads to a substantially equal flow through the modules. In
particular if each module comprises at least one particulate filter for reducing the particulate content in the exhaust gas, uniform loading and if appropriate also a uniformly changing pressure loss is advantageously achieved.
A first module may be formed in such a way that it alone or in combination with a further module is adapted to the exhaust-gas situation at the partial load point, while a second module may be formed in such a way that it, in conjunction with a further module and the first module, is adapted to the exhaust-gas situation at the full load point. In this way, a modular structure and a suitable diversion of the exhaust gas can in each case lead to optimum conversion of the exhaust gas at the various load points.
A module generally comprises at least one honeycomb body which comprises cavities, for example passages, through which an exhaust gas can flow. A honeycomb body may in particular comprise a ceramic and/or a metallic honeycomb body. A ceramic honeycomb body can be produced as an extruded monolith, while a metallic honeycomb body may comprise at least one at least partially structured layer, which has in particular been deformed in such a way as to form cavities through which an exhaust gas can flow. This deformation is to be understood in particular as meaning winding or twisting of at least one stack composed of at least one metallic layer. It is in this case also possible to use substantially smooth layers which together with the structures of the at least partially structured layer form the cavities. The honeycomb body may also comprise walls which in part allow a fluid to flow through them. The honeycomb body may form or comprise a particulate filter.
The effectiveness of an exhaust-gas treatment is highly
dependent on the flow conditions through the corresponding module. For example, it is advantageous in particular for there to be as far as possible no laminar flows within the module, but rather for the flows as far as possible to be turbulent. It is in this way possible to effectively avoid laminar boundary flows which result in only a small part of the exhaust gas coming into contact with the walls of the cavities in the honeycomb body, which generally have a catalytically active coating. This is particularly important if an open particulate filter is included in the module, since the effectiveness of such a filter is highly dependent on a corresponding turbulent flow. In particular in the case of large-volume internal combustion engines, however, the generally large dimensions of the corresponding exhaust-gas systems as well as the low idling speed of such engines in idling mode means that the exhaust-gas mass flow is very low, resulting in low flow velocities. This leads to a relatively low Reynolds number of the flow as it flows through the modules and therefore to possibly too low a degree of turbulence. Here, the process according to the invention can lead to an increase in the Reynolds number by, as it were, reducing the total available surface area of the modules for the exhaust gas to flow through in order to be treated, thereby increasing the flow velocity and Reynolds number.
By way of example, it is possible for a corresponding exhaust-gas system to comprise four modules for reducing the particulate concentration in the exhaust gas. In idling mode, the installation is operated in such a way, through suitable actuation of the connecting means, that in each case only one of four possible modules has the exhaust gas flowing through it. Although this also reduces the maximum available reaction and respectively filtration surface area, it particularly advantageously leads to an increase in the
flow velocity and therefore to an increase in the Reynolds number of the flow. However, there is no disadvantage in the lower reaction and/or filter surface area, since under idling conditions in particular the level of particulates is so low that the corresponding filter or reaction surface area of the module is sufficient to achieve enough conversion and respectively filtering. In this way, even in idling mode of large-volume internal combustion engines, the exhaust gas can be effectively treated. This is advantageous since in particular in large-volume internal combustion engines there are prolonged idling or low-load phases, for example when switching locomotives are waiting for the next switch or for ship engines which for example in port are used only to supply power.
As the load rises, i.e. for example as the internal combustion engine speed increases, it is possible, for example, to gradually switch further modules to have exhaust gas flowing through them. At higher engine speeds, a higher mean exhaust-gas velocity and a higher exhaust-gas mass flow are generally present, and consequently it is then advantageous for the exhaust gas to flow through a plurality of modules in order to provide a sufficiently large reaction and respectively filter surface area.
According to an advantageous refinement of the process according to the invention, in each module at least a reduction in the particulate concentration of the exhaust gas flowing through the module takes place.
For this purpose, a particulate filter may in particular be formed in each of the modules. The formation of further components is possible and advantageous; by way of example, a suitable oxidation catalyst on a honeycomb body may be formed upstream of
the particulate filter, leading in particular to oxidation of nitrogen monoxide (NO) to nitrogen dioxide (N02) , which serves as an oxidizing agent for the carbon contained in the particulates. A particulate filter of this type is known as a continuously regenerating particulate filter (CRT, continuous regenerating trap).
According to a further advantageous configuration of the process according to the invention, the reduction in the particulate concentration takes place in an open particulate filter.
An open particulate filter is to be understood as meaning a particulate filter in which the exhaust gas flowing through the particulate filter does not have to flow through a wall of the particulate filter. The alternative is a closed particulate filter, in which a multiplicity of passages are formed, of which in each case some are open on the entry side and closed on the exit side, while others are closed on the entry side and open on the exit side. In this way, the exhaust-gas stream is forced to flow through the porous wall of the particulate filter, in order to pass from a passage that is open on the entry side into a passage that is open on the exit side. As the exhaust gas flows through the wall, the particulates which it contains are filtered out. Open filters are also understood as bypass flow filters in which there is no filtering of the main stream, for example by a diesel particulate filter with passages closed on alternate sides, but rather only filtering of a bypass flow.
An open particulate filter therefore cannot per se become blocked. Although it is theoretically possible for the porous walls used as filter surfaces to become laden with particulates to such an extent that particulates are no longer filtered, in this case the
unfiltered exhaust gases can continue to flow through the particulate filter unimpeded; by contrast, a closed filter in which the filter surfaces become blocked forms a very high back-pressure which ultimately means that exhaust gas can no longer flow through the particulate filter. In this respect, an open particulate filter can also be understood as a barrier-free particulate filter.
In the case of an open particulate filter, it is particularly preferable for the filter to be composed of substantially smooth layers and at least partially corrugated layers. In particular, in this case the substantially smooth layer, at least in partial regions, may be composed of a material through which a fluid can flow and which is in particular porous, while the at least partially corrugated layer is composed for example of thin metal sheet or a thin sheet-metal foil or a thin metal foil. The corrugated layer may preferably have guide structures which are responsible for diverting the exhaust gas toward the filter regions. With regard to the configuration of these or similar guide structures, it is preferable for the structures to effect an increase in the velocity of the exhaust gas in the passage, so that in particular the proportion of the exhaust gas which remains in the open passage and flows past or along the filter surface is at a significantly increased velocity compared to the velocity of the exhaust gas when it enters the passage. Tests have shown that as the velocity of this bypass exhaust-gas stream increases the separation rate of the filter surface(s) or the particulate trap can be increased.
The process according to the invention is advantageous in particular for an open particulate filter which is in each case comprised within the modules, since in this case it is ensured even at low idling speeds of in
particular even large-volume internal combustion engines that the flow in the modules has a Reynolds number which during flow through the particulate filter is sufficiently high to nevertheless bring about effective removal of the particulates or conversion of the component.
According to a further advantageous configuration of the process according to the invention, a diversion of the exhaust gas takes place as a function of at least one of the following variables:
4.1) a regeneration capacity of the exhaust gas for a
module and
4.2) a need for regeneration of a module.
In this context, a diversion of the exhaust gas is to be understood as meaning a diversion by the connecting means. A regeneration of a particulate filter comprises in particular an oxidation of the particulates held in the particulate filter. This can be effected firstly by providing an oxidizing agent, such as for example nitrogen dioxide, or as an alternative or indeed an addition for example by additional heating measures which increase the temperature of the particulate filter above a limit temperature above which the particulates are preferentially oxidized. If the exhaust gas is at a certain temperature that can lead to increased regeneration during flow through a module, it is possible to refer to a regeneration capacity of the exhaust gas as defined in 4.1) above. On the other hand, a need for reaction 4.2) of a module as referred to above, for example in the case of a particulate filter, means that the quantity of particulates that are present has exceeded a limit value above which it is advantageous to regenerate the module. In particular in a particulate filter, this may also manifest itself in a rise in the pressure loss across said particulate filter.
According to a further advantageous configuration of the process according to the invention, in an idling load state the exhaust-gas stream is diverted in such a way that on average a substantially identical total exhaust-gas stream flows through substantially all the modules.
In this context, a total exhaust-gas stream is to be understood as meaning the sum and/or the temporal integral of the exhaust-gas stream, preferably of the exhaust-gas mass flow or the exhaust-gas volumetric flow, over the time during which the exhaust gas flows through the module in question. The total exhaust-gas stream therefore preferably constitutes a mass, if it is the exhaust-gas mass flow that is under consideration, or a volume, if it is the exhaust-gas volumetric flow that is under consideration. In this context, in particular through-flow times of up to 5 minutes, up to 10 minutes or even of an hour or more are possible and in accordance with the invention. In principle, it is preferable here to adopt a procedure in which the flow velocity in a module, preferably in a passage of a honeycomb body that is at least part of a module, lies in the range from 10 meters per second to 25 meters per second.
According to a further advantageous configuration of the process according to the invention, the number of modules through which the exhaust gas flows increases monotonically to at least one of the following variables:
6.1) exhaust-gas temperature and
6.2) exhaust-gas mass flow.
It is particularly advantageous to be dependent on the exhaust-gas mass flow, since otherwise, for example if the exhaust gas is flowing through just one module, at
higher loading states, in particular even at full load, flow through just one module may be disadvantageous for the effectiveness of exhaust-gas treatment. In particular if each of the modules comprises an open particulate filter, it is advantageous if the exhaust gas flows through all the modules up to the full-load state of the internal combustion engine. Regeneration of the particulate filters in question can also take place in particular during the full-load state.
A further aspect of the present invention proposes an apparatus for treating an exhaust gas from an internal combustion engine, comprising an exhaust pipe, which can be connected to the internal combustion engine, and at least two modules for exhaust-gas treatment, which can be connected to the exhaust pipe, wherein at least one connecting means assigned to at least one module is formed, by which connecting means said module can be connected to the exhaust pipe in such a way that at least part of the exhaust gas can flow through said module.
Each module comprises in particular a honeycomb body, which preferably comprises a corresponding catalytically active coating and/or is suitable for particulate filtering. A connecting means is to be understood in particular as meaning a component by means of which a connection to the module through which a fluid can flow can be produced or disconnected. The connecting means is preferably a correspondingly designed flap, which in the closed state can close a through-flow opening leading to the module and in the open state can open up this opening. In particular, the various connecting means can be formed in such a way that in each case only part of the exhaust gas can flow through the associated module or alternatively all of the exhaust gas can flow through the associated module. In particular in the case of the latter option, various
connecting means can interact.
According to an advantageous configuration of the apparatus according to the invention, the connecting means are formed in such a way that exhaust gas can flow through each module alone.
Thus, the apparatus according to the invention can be operated in such a way that in particular in idling mode exhaust gas flows to a uniform extent through the individual modules, so that the individual modules are utilized equally. In particular if the modules comprise particulate filters, it is in this way possible to achieve a substantially uniform loading of the particulate filters in the modules. This leads to a substantially uniform pressure loss across the respective modules.
According to a further advantageous configuration of the apparatus according to the invention, each module effects at least a reduction in the particulate concentration of the exhaust-gas stream flowing through the module.
In this case, it is preferable for each module to comprise at least one particulate filter, which is particularly preferably open. For a definition of an open particulate filter, reference is made to the statements made above and to WO 02/00326 A2, the content of disclosure of which in connection with the design of the particulate filter is hereby incorporated in the present invention.
According to a further advantageous configuration of the apparatus according to the invention, the connecting means comprises at least one flap.
A flap constitutes a connecting means that is on the
one hand simple to produce and is able to effectively produce or stop a connection to a module. Furthermore, flaps are simple to actuate and have proven stable and durable when used in exhaust-gas systems.
According to a further configuration of the apparatus according to the invention, the connecting means is configured in such a way that when the exhaust gas can flow through the associated module it excludes at least one further module from the exhaust-gas flow.
This can be realized in particular by a flap that has
three possible positions:
1.) a first position, in which the connection to the
module is closed, 2.) a second position, in which the connection to the
module is open and the exhaust pipe is blocked, so
that all the exhaust gas that is present at the
connection to the module flows through this
module, and 3.) a third position, in which exhaust gas can flow
freely through both the module and the exhaust
pipe.
Flaps of this type can be used in particular to realize an apparatus according to the invention in which exhaust gas can flow through all the modules individually.
The invention also proposes a rail-borne vehicle, preferably a railway motor car, particularly preferably a locomotive, which comprises an apparatus according to the invention or in which a process according to the invention takes place.
The invention also proposes a water-borne vehicle which comprises an apparatus according to the invention or in which a process according to the invention takes place.
The process and apparatus according to the invention can particularly advantageously be deployed in exhaust-gas systems of diesel engines. It is preferable for the rail-borne vehicle and the water-borne vehicle also to have a diesel engine. Furthermore, it is possible for the apparatus and process according to the invention to be used in stationary internal combustion engines, in particular diesel internal combustion engines.
The advantages and details which have been disclosed in respect of the process according to the invention can also be transferred to and exploited in the same way in the apparatus according to the invention. The same also applies to the details and advantages disclosed in respect of the apparatus according to the invention, which can equally be transferred to and exploited in the process according to the invention. The apparatus according to the invention is suitable in particular for carrying out the process according to the invention.
In the text which follows, the invention is to be explained in more detail with reference to the accompanying figures, without the invention being restricted to the details and advantages shown therein. In the drawing:
fig. 1 diagrammatically depicts a first exemplary embodiment of an apparatus according to the invention;
fig. 2 diagrammatically depicts an excerpt from a module of an apparatus according to the invention;
fig. 3 diagrammatically depicts an end-on view of a module of an apparatus according to the invention;
fig. 4 diagrammatically depicts a first longitudinal section through a second exemplary embodiment of an apparatus according to the invention;
fig. 5 shows a second longitudinal section through the second exemplary embodiment of an apparatus according to the invention;
fig. 6 shows an excerpt from an apparatus according to the invention with a connecting means in a first position;
fig. 7 shows an excerpt from an apparatus according to the invention with a connecting means in a second position; and
fig. 8 diagrammatically depicts an excerpt from an apparatus according to the invention with a connecting means in a third position.
Fig. 1 diagrammatically depicts a first exemplary embodiment of an apparatus 1 according to the invention for treating an exhaust gas 6. Said apparatus comprises an exhaust pipe 2, a first module 3 and a second module 4 for exhaust-gas treatment. An idling module 5 is also formed. The internal combustion engine (not shown) emits an exhaust gas 6 which flows through the exhaust pipe 2 in a through-flow direction 7. The first module 3 for exhaust-gas treatment is assigned a first connecting means 8. In the present, first exemplary embodiment, said connecting means 8 comprises a pivotable flap, by means of which the module 3 can be connected to the exhaust pipe 2 in such a way that at least part of the exhaust gas 6 can flow through said module 2. A second connecting means 9 is formed in a corresponding way and is assigned to the second module

4 for exhaust-gas treatment.
The idling module 5 is not assigned a connecting means, since the exhaust gas 6 flows through this idling module 5 even when the first connecting means 8 and the second connecting means 9 are in a first position preventing flow through the first module 3 and the second module 4. In particular for large-volume internal combustion engines, for example of locomotives, of water-borne vehicles, such as in particular ships or boats, and of stationary installations, it is advantageous for the idling module
5 to be adapted to the exhaust-gas situation during
idling phases. By way of example, in the case of a
switching locomotive, the internal combustion engine is
in idling mode for a very large part of its operating
time, and it is therefore useful to adapt to idling
conditions. Moreover, large-volume internal combustion
engines have a very low idling speed and very low flow
velocities and consequently low Reynolds numbers in
idling mode. If the exhaust gas 6 also in idling mode
were to flow through both the idling module 5 and also
the first module 3 and the second module 4 for exhaust-
gas treatment, the result would be a very low Reynolds
number of the exhaust-gas flow in all the modules 3, 4,
5. This would lead to more of a laminar flow, which is
generally undesirable in modules for exhaust-gas
treatment.
If, for example, open particulate filters are comprised within the modules 3, 4, 5, however, laminar flow through these particulate filters is undesirable. Fig. 2 diagrammatically depicts an excerpt from an open particulate filter of this type. An open particulate filter of this type is formed, for example, from corrugated metallic layers 10 and substantially smooth layers 11. The substantially smooth layer 11 is formed from a material which at least in part allows a fluid
to flow through it, for example a sintered porous material or a porous fiber material.
Here, the corrugated metallic layer has apertures 12 which form guide vanes 13. The substantially smooth layers 11 and the corrugated metallic layers 10 form passages 14 through which the exhaust gas 6 can flow. The exhaust gas 6 follows the indicated flow lines. The apertures 12 and guide vanes 13 cause the exhaust gas 6 to be guided through the substantially smooth layer 11. The particulates 15 contained in the exhaust gas 6 accumulate in the substantially smooth layer 11.
A module 3, 4, 5 may comprise at least one honeycomb body 16, as diagrammatically depicted in cross section from fig. 3. The honeycomb body 16 is in this case formed from corrugated metallic layers 10 and substantially smooth layers 11. These have been stacked to form three stacks, and these stacks are then intertwined so as to form passages 14. In addition to a particulate filter, it is also possible to form other types of honeycomb bodies. By way of example, it is possible to form honeycomb bodies 16 which support a catalytically active coating and/or are formed just from metal foils. In particular, this catalytically active coating may comprise washcoat comprising catalytically active particulates. In particular, it is also advantageous if a module 3, 4, 5 comprises an oxidation catalyst, the catalytically active centers of which catalyze at least the oxidation of nitrogen monoxide to nitrogen dioxide and comprise a corresponding open particulate filter downstream of this oxidation catalyst. The nitrogen dioxide formed in this way can then advantageously be used to regenerate the particulate filter, i.e. to oxidize the particulates 15. Both the substantially smooth layers 11 and the corrugated layers 10 may be formed from thin metal foils. It is possible to do without the formation
of guide vanes 13 and apertures in particular if the honeycomb body 16 is used not as a particulate filter but rather exclusively as a support for a catalytically active coating.
Fig. 4 diagrammatically depicts a second exemplary embodiment of an apparatus 1 according to the invention for exhaust-gas treatment. This apparatus 1 comprises an exhaust pipe 2, a first module 3, a second module 4, a third module 17 and a fourth module 33 for exhaust-gas treatment. An idling module is not provided here. Furthermore, a first connecting means 8, a second connecting means 9 and a third connecting means 18 are formed and assigned to the respective modules 3, 4, 17. The connecting means 8, 9, 17 therefore number one fewer than the modules 3, 4, 17, 22. The connecting means 8, 9, 17 are formed in such a way that exhaust gas can flow through each module 3, 4, 17, 22 alone. The exhaust gas emitted by an internal combustion engine 19 can in this way be advantageously diverted by means of the connecting means 8, 9, 18, as a function of a loading state of the internal combustion engine 19, in such a way that at least parts of the exhaust gas flow through one or more modules 3, 4, 17, 22 for exhaust-gas treatment.
In particular, according to the second exemplary embodiment of an apparatus 1 according to the invention, it is advantageously possible in the idling state to divert the exhaust-gas stream in such a way that on average a substantially identical total exhaust-gas stream flows through all the modules 3, 4, 17, 22. Therefore, in idling mode, substantially all the modules 3, 4, 17, 22 are acted on substantially uniformly.
Fig. 5 diagrammatically depicts a further longitudinal section through the second exemplary embodiment of an
apparatus 1 according to the invention for treating an exhaust gas from an internal combustion engine 19. Each of the modules 3, 4, 17, 22 comprises a plurality of honeycomb bodies 16. Each of the honeycomb bodies 16 may comprise various zones. This will be explained in more detail below on the basis of the example of the honeycomb bodies 16 of the fourth module 22. Each of the honeycomb bodies 16 of the fourth module 22 comprises an oxidation catalyst zone 20 and a particulate filter zone 21. These zones 20, 21 are arranged in such a way that the exhaust gas flows firstly through the oxidation catalyst zone 20 and then through the particulate filter zone 21. Further catalyst zones are also shown in the further modules 3, 4, 17 and are formed in such a way that they are adapted to the respective loading states at which these modules 3, 4, 5, 17 are connected up. They may in particular be further oxidation catalyst zones 20, zones for conversion of nitrogen oxides and standard three-way catalyst zones. These are only examples; other catalyst zones are possible and covered by the scope of the invention. As an alternative to having a plurality of zones 20, 21 per module 3, 4, 17, 22, it is also possible for a plurality of corresponding honeycomb bodies 16 to be formed in series.
In particular, the apparatus for treating an exhaust gas can be operated in such a way that the diversion of the exhaust gas effected by the connecting means 8, 9, 18 takes place as a function of the regeneration capacity of the exhaust gas 6 and a need for regeneration of a module 5, 3, 4, 17, 22. This means that when the exhaust gas satisfies certain parameters required for the regeneration of the particulate filter zones 21, for example exceeds a certain limit temperature, this exhaust gas is passed in a targeted way to a module 3, 4, 17, 22 that is in need of regeneration. This can be effected in particular by the
connecting means 8, 9, 18, which are formed in such a way that, in addition to a connection of the respective modules 5, 3, 4, 17, 22, it is also possible to prevent flow through other modules. Oxidation catalyst zone 20 and particulate filter zone 21 may also be formed as individual honeycomb bodies 16 through which exhaust gas can flow in succession.
Fig. 6 diagrammatically depicts an excerpt from an
apparatus 1 according to the invention. Here, a
connecting means 8 assigned to a first module for
exhaust-gas treatment 3 is in a first position, with
the result that the exhaust gas 6 from the internal
combustion engine 19 does not flow through the first
module 3, but rather bypasses it.
Fig. 7 diagrammatically depicts the same excerpt from an apparatus according to the invention, in which the connecting means 8 has adopted a second position. This closes the exhaust pipe 2 so that the exhaust gas 6 from the internal combustion engine 19 flows through the module 3. Depending on whether further modules are also formed upstream of the first module 3, either all of the exhaust gas 6 from the internal combustion engine flows through the first module 3 or only a corresponding proportion of the exhaust gas 6 does so. The proportion in this case depends on the pressure losses in the parts of the exhaust-gas system through which the exhaust gas can flow.
Fig. 8 diagrammatically depicts the connecting means 8 in a third position. Here, access to the first module 3 is open, so that a part of the exhaust gas 6 can flow through the module 3. However, a further part of the exhaust gas 6 can flow onward through the exhaust pipe 2. The distribution of the part-streams which flow through the exhaust pipe 2 and the module 3 is dependent on the pressure loss in the respective
partial regions 2, 3 through which the exhaust gas is to flow.
Forming the connecting means 8, 9, 18 in a corresponding or similar way to that shown in figures 6 to 8 advantageously makes it possible to implement a procedure in which exhaust gas can flow through each module individually. This in particular means that it is advantageously possible, in particular in idling mode, for each module 3, 4, 17, 22 to be fed in particular with a substantially uniform total exhaust-gas stream.
The process according to the invention and the apparatus 1 according to the invention advantageously enable even the exhaust-gas systems of large-volume internal combustion engines 19 to be configured in such a way that, even in idling mode and in principle at very low exhaust-gas mass flow rates, the exhaust gas 6 is converted and treated in individual modules 5, 3, 4, 17, 22. The individual modules can be adapted to different load points of the internal combustion engine 19.
List of reference numerals
1 Apparatus for treating an exhaust gas from an
internal combustion engine
2 Exhaust pipe
3 First module for exhaust-gas treatment
4 Second module for exhaust-gas treatment
5 Idling module
6 Exhaust gas
7 Through-flow direction
8 First connecting means
9 Second connecting means
10 Corrugated metallic layer
11 Substantially smooth layer
12 Aperture
13 Guide vane
14 Passage
15 Particulate
16 Honeycomb body
17 Third module for exhaust-gas treatment
18 Third connecting means
19 Internal combustion engine
20 Oxidation catalyst zone
21 Particulate filter zone
22 Fourth module for exhaust-gas treatment

Claims
1. A process for treating an exhaust gas (6) from an
internal combustion engine (19), wherein at least two
modules (3, 4, 5, 17, 22) are formed for treating the
exhaust gas and characterized in that an exhaust-gas
stream can be diverted at least in part as a function
of a loading state of the internal combustion engine
(19) in such a way that at least parts of the exhaust
gas (6) flow through one or more modules (3, 4, 5, 17,
22) .
2. The process as claimed in claim 1, wherein in each
module (3, 4, 5, 17, 22) at least a reduction in the
particulate concentration of the exhaust gas (6)
flowing through the module takes place.
3. The process as claimed in claim 2, wherein the
reduction in the particulate concentration takes place
in an open particulate filter.
4. The process as claimed in claim 3, wherein a
diversion of the exhaust gas (6) takes place as a
function of at least one of the following variables:

4.1) a regeneration capacity of the exhaust gas for a
module (3, 4, 5, 17, 22) and
4.2) a need for regeneration of a module (3, 4, 5, 17,
22) .

5. The process as claimed in one of the preceding
claims, wherein in an idling load state the exhaust-gas
stream is diverted in such a way that on average a
substantially identical total exhaust-gas stream flows
through substantially all the modules (3, 4, 5, 17,
22) .
6. The process as claimed in one of the preceding
claims, wherein the number of modules (3, 4, 5, 17, 22)

through which the exhaust gas flows increases monotonically to at least one of the following variables:
6.1) exhaust-gas temperature and
6.2) exhaust-gas mass flow.
7. An apparatus (1) for treating an exhaust gas (6)
from an internal combustion engine (19), comprising an
exhaust pipe (2), which can be connected to the
internal combustion engine (19), and at least two
modules (3, 4, 5, 17, 22) for exhaust-gas treatment,
which can be connected to the exhaust pipe (2),
characterized in that at least one connecting means (8,
9, 18) assigned to at least one module (3, 4, 5, 17,
22) is formed, by which connecting means said module
(3, 4, 5, 17, 22) can be connected to the exhaust pipe
(2) in such a way that at least part of the exhaust gas
(6) can flow through said module (3, 4, 5, 17, 22).
8. The apparatus (1) as claimed in claim 7, wherein
the connecting means (8, 9, 18) are formed in such a
way that exhaust gas can flow through each module (3,
4, 5, 17, 22) alone.
9. The apparatus (1) as claimed in either of claims 7
and 8, wherein each module (3, 4, 5, 17, 22) effects at
least a reduction in the particulate concentration of
the exhaust-gas stream flowing through the module (3,
4, 5, 17, 22) .
10. The apparatus (1) as claimed in claim 9, wherein
each module (3, 4, 5, 17, 22) comprises at least one
particulate filter.
11. The apparatus (1) as claimed in claim 11,
characterized in that the particulate filter is open.
12. The apparatus (1) as claimed in one of claims 7 to

11, wherein the connecting means (8, 9, 18) comprises
at least one flap.
13. The apparatus (1) as claimed in one of claims 7 to
12, wherein the connecting means (8, 9, 18) is
configured in such a way that when the exhaust gas (6)
can flow through the associated module (3, 4, 5, 17,
22) it excludes at least one further module (3, 4, 5,
17, 22) from the exhaust-gas flow.
14. A rail-borne vehicle, comprising an apparatus as
claimed in one of claims 7 to 13.
15. A water-borne vehicle, comprising an apparatus as
claimed in one of claims 7 to 13.

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Patent Number

279765

Indian Patent Application Number

1339/DELNP/2008

PG Journal Number

05/2017

Publication Date

03-Feb-2017

Grant Date

30-Jan-2017

Date of Filing

15-Feb-2008

Name of Patentee

EMITEC GESELLSCHAFT FUR EMISSIONSTECHNOLOGIE MBH

Applicant Address

HAUPTSTRASSE 128, 53797 LOHMAR GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	TREIBER PETER	HAFERBUCKEL 22, 40789 MONHEIM GERMANY

PCT International Classification Number

F01N 3/035

PCT International Application Number

PCT/EP2006/007975

PCT International Filing date

2006-08-11

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2005 038 707.1	2005-08-15	Germany