Reducing agent decomposition system

Abstract

Reducing agent decomposition system (40), comprising: an exhaust gas chamber (44) having an inlet (46) and an outlet (48), wherein the exhaust gas chamber (44) has a non-cylindrical and non-linear shape; a first exhaust gas distribution component (60) positioned in the exhaust gas chamber (44) and which can be brought into exhaust gas receiving communication with the inlet (46), wherein the first exhaust gas distribution component (60) is configured to produce swirl exhaust gas flow profiles in the exhaust gas chamber (44); a second exhaust gas distribution component (70) positioned in the exhaust gas chamber (44) and which can be brought into exhaust gas supply communication with the outlet (48), wherein the second exhaust gas distribution component (70) has a plurality of circumferentially arranged vanes (114) and corresponding slots (112) configured to produce a swirl exhaust gas flow profile in the second exhaust gas distribution component (70);and a reducing agent injector (50) coupled to the exhaust gas chamber (44), wherein the reducing agent injector (50) can be brought into contact with the exhaust gas in the exhaust gas chamber (44) for reducing agent injection.

Description

[0001] The present invention relates to exhaust systems for internal combustion engines and in particular to a reducing agent decomposition system for a catalyst for the selective catalytic reduction (SCR catalyst, SCR-selective catalytic reduction) of an exhaust aftertreatment system.

[0002] Exhaust aftertreatment systems receive and treat exhaust gas produced by an internal combustion engine. Typical Exhaust aftertreatment systems contain various components designed to reduce harmful exhaust emissions. Exhaust gases are present and configured. For example, some exhaust aftertreatment systems for diesel combustion engines contain various components. Components such as a diesel oxidation catalyst (DOC), a particulate filter or diesel particulate filter (DPF) diesel particulate filter) and an SCR catalyst (SCR - selective catalytic reduction). In some exhaust aftertreatment systems, exhaust gas flows first through the diesel oxidation catalyst, then through the diesel particulate filter and finally through the SCR catalyst.

[0003] Each of the DOC, DPF and SCR catalyst components is configured to perform a specific exhaust emission treatment process. through which the exhaust gas flows. In general, the DOC reduces the amount of carbon monoxide and Hydrocarbons present in the exhaust gas are removed via oxidation techniques. The DPF filters out harmful diesel particles and soot. is present in the exhaust gas. Ultimately, the SCR catalyst reduces the amount of nitrogen oxides (NOx) present in the exhaust gas.

[0004] The SCR catalyst is used to reduce NOx to less harmful emissions, such as N2 and H2O, in the presence of Ammonia (NH3) is configured. Since ammonia is not a natural byproduct of the combustion process, it must be artificially introduced into the exhaust gas. ammonia is removed before the exhaust gas enters the SCR catalyst. This is usually due to safety concerns related to the SCR process. Liquid ammonia is stored and not injected directly into the exhaust gas. Accordingly, conventional systems are designed to use a urea- Injecting a water solution into the exhaust gas, which can decompose into ammonia in the presence of the exhaust gas. SCR systems typically contain this solution. a urea source and a urea injector or doser coupled to the source and positioned upstream of the SCR catalyst.

[0005] In general, the decomposition of the urea-water solution to gaseous ammonia occurs in three stages. First, urea evaporates. or mixes with exhaust gas. Secondly, the temperature of the exhaust gases causes a phase change in the urea and decomposition of the urea. to isocyanic acid (HNCO) and water. Thirdly, isocyanic acid reacts with water in a hydrolysis process under specific pressure- and temperature concentrations for decomposition into ammonia and carbon dioxide (CO2). Then the ammonia is removed at the inlet surface of the SCR- The NOx is introduced into the catalyst, flows through the catalyst, and is consumed in the NOx reduction process. Any NOx leaving the SCR system that is not Used ammonia can be converted to N2 and other less harmful or less toxic gases using an ammonia oxidation catalyst. Components will be reduced.

[0006] In order for sufficient decomposition to ammonia, the injected urea must be given sufficient time to carry out the three stages. The time given to carry out the three stages and to decompose urea to ammonia before entering the SCR catalyst. This is conventionally called residence time. State-of-the-art exhaust aftertreatment systems use a long pipe with a a defined linear decomposition length extending between the urea injector and the SCR catalyst inlet surface. The defined The linear decomposition length of state-of-the-art systems must be quite long to provide the required residence time. Long pipelines for urea decomposition often require valuable space that is occupied by other vehicle components. could, and influence the design of the exhaust aftertreatment system.

[0007] Although some prior art exhaust aftertreatment systems that use long decomposition tubes, the Furthermore, such systems often fail to provide sufficient time for urea decomposition. Mixing the urea / ammonia with the exhaust gas. Insufficient mixing leads to a low uniformity index of ammonia vapor. which leads to an accumulation of crystallization / polymerization in the SCR catalyst or other SCR system components, localized Ammonia aggregation, insufficient distribution of ammonia over the SCR catalyst surface, and a lower NOx conversion efficiency. and other disadvantages may result.

[0008] Furthermore, in many exhaust aftertreatment systems, there is an insufficient distribution of exhaust gas over the inlet area. of the SCR catalyst. An uneven distribution of exhaust gas at the SCR catalyst inlet can lead to... The exhaust gas flow distribution index at the SCR catalyst, for example, ensures that a smaller proportion of the SCR catalyst surface is exposed to the exhaust gases. The smaller the proportion of the catalyst surface in contact with the exhaust gases, the lower the NOx reduction performance of the catalyst. SCR catalyst.

[0009] The subject matter of the present application has been developed in response to the current state of the art and in particular in response to the problems and requirements of the technology posed by currently available exhaust aftertreatment systems, which include an SCR- The system requirements that have not yet been fully resolved are not yet fully solved. Accordingly, the subject matter of the present application has been developed to enable a to provide a reducing agent decomposition system and associated facilities and procedures that include at least some of the following or others Overcoming the disadvantages of state-of-the-art reducing agent decomposition techniques.

[0010] The invention relates to a reducing agent decomposition system having the features of claim 1. Preferred improvements and Modifications of this reducing agent decomposition system are the subject of dependent claims 2 to 6. Furthermore, the invention relates to an exhaust aftertreatment system according to claim 7 with dependent claims 8 and 9. Finally, the invention relates to a method for Decomposition of urea to ammonia according to claim 10 with the modifications and improvements described in dependent claim 11.

[0011] In a representative embodiment, a reducing agent decomposition system includes an exhaust gas chamber which has an inlet and The system has an outlet. Furthermore, it includes a first exhaust gas distribution component, which is positioned in the chamber and connected to the The outlet can be connected to the exhaust gas receiving system. The first exhaust gas distribution component creates swirl exhaust gas flow profiles in the Exhaust chamber. Furthermore, the system includes a second exhaust distribution component positioned within the chamber and connected to the inlet. The exhaust gas supply connection can be brought in. The second exhaust gas distribution component contains features that create a swirl exhaust gas flow profile in a The system is defined by the second exhaust gas distribution component. Furthermore, it includes a reducing agent injector that is connected to the The exhaust gas chamber is coupled. The reducing agent injector can be brought into contact with the exhaust gas in the chamber for reducing agent injection.

[0012] In some implementations of the system, the inlet and outlet of the exhaust chamber are essentially coplanar. The exhaust chamber has a width and a length, with the width being at least approximately 0.25 times the length. In certain cases... In this implementation, the reducing agent decomposition length of the exhaust aftertreatment system is greater than the axial length between the inlet. and the exhaust chamber outlet. In certain implementations, the exhaust chamber is located near the first exhaust distribution component. greater than the height of the exhaust chamber near the second exhaust distribution component.

[0013] In some implementations of the system, the first exhaust gas distribution component includes a first set of small perforations and a second set of large perforations. The small perforations of the first set face the reducing agent injector, and the large ones The perforations of the second set are directed away from the reducing agent injector. The first set of small perforations can be configured to to generate a turbulent exhaust flow, and the second set of large perforations can be configured to create an essentially convective To generate exhaust gas flow.

[0014] In some implementations, the first exhaust gas distribution component includes a perforated tube with a first open end, a second partially closed end and a side wall extending between the first open end and the second closed end. The perforated tube can contain multiple perforations formed in the side wall and in the partially closed end. Multiple perforations can form a first set of perforations that are located in the second, partially closed end, a second A set of perforations formed in a first part of the side wall, and a third set of perforations formed in a second part. Part of the side wall is formed. The first set of perforations can define an initial percentage of open area, which The second set of perforations can define a second percentage of open area, and the third set of perforations can define a third. Define the percentage of open space. In certain implementations, the second percentage of open space is larger than the first. Percentage of open area and the third percentage of open area is greater than the second percentage of open area.

[0015] In other implementations, the second exhaust gas distribution component contains several wings and corresponding slots which serve to The second exhaust distribution component is configured to generate an exhaust gas vortex. Furthermore, the second exhaust distribution component can be configured to... Contraction tube with one open end, one closed end It contains an end and a side wall extending between the open and closed ends. The multiple wings and slots They can extend longitudinally along at least part of the side wall. In some implementations, each of the multiple wings angled relative to the side wall at a point near each wing, with each wing extending from an outer surface of the side wall extends outwards and from an inner surface of the side wall inwards. The area between each of the multiple wings and the side wall The angle formed at the point near each wing can be determined by a distance between the open end of the contraction tube and a Exhaust aftertreatment device located downstream of the open end of the contraction pipe.

[0016] According to another embodiment, an exhaust aftertreatment system includes a diesel particulate filter, a catalyst for the selective catalytic reduction, a urea decomposition chamber and a urea injector coupled to the urea decomposition chamber. The decomposition chamber contains an inlet that can be connected to the diesel particulate filter for exhaust gas reception, and an outlet. which can be brought into contact with the catalyst for selective catalytic reduction in the exhaust gas feed system. The urea injector can be used with exhaust gas. in the urea decomposition chamber, they are brought into urea injection compound.

[0017] Furthermore, the system can include an exhaust gas distribution component that is positioned in the chamber and connected to the inlet of the chamber. can be brought into exhaust gas receiving connection. The exhaust gas distribution component can have a first set of perforations, each of which provides a first The first area has a surface and contains a second set of perforations, each with a second surface. The first area is significantly larger. than the second surface.

[0018] Furthermore, the system can include an exhaust gas distribution component that is positioned in the chamber and connected to the outlet of the chamber. can be brought into the exhaust gas supply connection. The exhaust gas distribution component can contain several vanes configured to direct the exhaust gas. to swirl in the exhaust gas distribution component to improve the distribution of reducing agent over the SCR catalyst inlet area in a to maintain a short distance from the SCR catalyst. The shape of the urea decomposition chamber is defined by its height, length, and width. where the length can be greater than the width and height, and the width can be greater than the height.

[0019] In some implementations, the cross-sectional shape of the urea decomposition chamber includes a section extending perpendicular to the The first and second exhaust flow direction plane has a first curved part extending around the inlet, and a second curved section that extends around the outlet. Exhaust gas from the diesel particulate filter flows from the inlet to the outlet of the Urea decomposition chamber. The first and second curved parts promote turbulence of exhaust gas in the urea decomposition chamber.

[0020] In another embodiment, a method for decomposing urea to ammonia comprises passing exhaust gas through a Perforation pattern and into a chamber. The perforation pattern causes turbulence of the exhaust gas in the chamber, thereby decomposing it. The injected urea is promoted by increasing the gas entropy. According to the laws of gas kinetics, increasing the gas entropy increases the reaction rate. Furthermore, the process includes injecting urea into the exhaust gas in the chamber. In addition, the Method of directing exhaust gas in the chamber between several vanes to further swirl the exhaust gas in the chamber.

[0021] In some implementations, the perforation pattern contains several first perforations, each having a first size, and several second perforations, each having a second size larger than the first size, conducting exhaust gas through a The perforation pattern includes the routing of exhaust gas through the first and second perforations. In this process, exhaust gas routing can be achieved in the... The chamber between the multiple blades causes the exhaust gas to swirl before it flows between the multiple blades and after it flows between the multiple blades. Furthermore, the multiple blades can be positioned around a central axis, and the process It can continue to direct a portion of the exhaust gas radially inwards towards the central axis after the exhaust gas flows between the multiple vanes. The process could include directing a portion of the exhaust gas radially outwards from the central axis. exhaust gases between the multiple wings.

[0022] Throughout this description, reference to features, advantages or similar expressions does not mean that all of these features and advantages that can be realized with the present invention, in any single embodiment or implementation of the The invention should be included or are included. Expressions relating to the features and advantages are intended to mean that a a special feature, advantage or characteristic that is described in connection with an embodiment, in at least one embodiment the present invention is contained within. A discussion of the features and advantages and similar expressions may be found in the entire The description refers to the same embodiment or implementation, but this is not necessarily the case.

[0023] The described features, advantages and properties of the invention can be achieved in one or more embodiments and / or Implementations can be combined in some suitable way. It is obvious to a person skilled in the art that the invention also without one or more of the special features or advantages of a particular embodiment or implementation It is possible. In other cases, certain embodiments and / or implementations may reveal additional features and advantages that These features and advantages of the present invention are not present in all embodiments of the invention. These features and advantages of the present invention will become apparent from the following: The description and the attached claims are more clearly evident, or can be learned by carrying out the invention as described below. become. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the advantages of the invention easier to understand, a more detailed description of the invention is given below. Reference is made to specific embodiments illustrated in the attached drawings. It is understood that these The drawings only show typical embodiments of the invention and are not to be considered as limiting its scope of protection. The invention is described and explained with additional precision by means of the drawings; these show:

[0025] Fig. 1 shows a perspective first end view of an exhaust aftertreatment system with a reducing agent decomposition system according to one embodiment;

[0026] Fig. 2 shows a perspective second end view of the exhaust aftertreatment system of Fig. 1;

[0027] Fig. 3 shows a cross-sectional view of the exhaust aftertreatment system as shown in Fig. 2 along line 3-3 of Fig. 2;

[0028] Fig. 4 shows a perspective end view of the exhaust aftertreatment system of Fig. 1, which includes the reducing agent decomposition system with a removed end cap shows;

[0029] Fig. 5 shows a side view of the exhaust aftertreatment system of Fig. 1, which is shown in cross-section with the end cap;

[0030] Fig. 6 shows a perspective view of a contraction tube of an exhaust gas distribution component of the reducing agent decomposition system of Fig. 4, where in the representation a closed end of the component is removed;

[0031] Fig. 7 shows a top view of the reducing agent decomposition system of Fig. 4 with the end cap in cross-section, showing exhaust gas flow profiles in a chamber of the reducing agent decomposition system according to one embodiment;

[0032] Fig. 8 shows a cross-sectional top view of the exhaust gas distribution component of Fig. 6, which shows a velocity contour diagram of the exhaust gas flow in the component according to a specific embodiment;

[0033] Fig. 9 shows a side view of the exhaust gas distribution component of Fig. 6 in cross-section, which shows a velocity contour diagram of the exhaust gas flow in the component according to a specific embodiment; and

[0034] Fig. 10 shows a method for decomposing urea to ammonia according to one embodiment. DETAILED DESCRIPTION

[0035] Throughout this description, reference to “an embodiment” or similar expressions means, that a specific feature, structure or property described in connection with the embodiment is included in at least one embodiment of the present invention. Common formulations such as “in a The terms “estate” and similar expressions can refer to the same state of embodiment throughout the description, which but this is not necessarily the case. Similarly, the use of the term "implementation" means an implementation, which has a specific characteristic, structure or property that, in conjunction with one or more Embodiments of the present invention are described, however, in the absence of an explicit correlation indicating otherwise, an implementation of one or more embodiments.

[0036] The described features, structures or properties of the invention can be incorporated in any suitable way into one or more Various embodiments can be combined. The following description provides a thorough overview. Understanding the embodiments of the invention reveals numerous specific details. However, for a person skilled in the field, it is clear that... The hand that the invention can also be performed without one or more of these special details or with other methods, components, materials, etc. can be exercised. In other cases, well-known structures, materials, or processes are not shown or described in detail. to avoid concealing aspects of the invention.

[0037] Various embodiments of a reducing agent decomposition system and associated equipment and processes are described here. among other things, to improve the decomposition of a reducing agent, such as urea, to ammonia in exhaust gas, improving the Mixing urea and ammonia with exhaust gas and improving the uniformity of the exhaust gas flow distribution into the SCR catalyst. described. The reducing agent decomposition system forms part of an exhaust aftertreatment system that includes an SCR system. In In one embodiment, the reducing agent decomposition system generally comprises a fixed-volume chamber with an inlet and an The system features a first exhaust distribution component near the chamber inlet and a second exhaust distribution component near the chamber outlet. In one implementation, the first exhaust distribution component incorporates a perforation pattern that creates a desired exhaust flow profile. around the chamber, which is responsible for mixing injected urea and urea decomposition byproducts with exhaust gas in the chamber is beneficial. In yet another implementation, the second exhaust gas distribution component facilitates a uniform distribution of the exhaust gas at a Inlet of the SCR catalyst. In certain implementations, the first and second exhaust gas distribution components, as well as the chamber, are extended. Furthermore, the urea decomposition residence time, and the second exhaust gas distribution component further improves the mixing of the injected fuel. Urea and the urea decomposition byproducts with exhaust gas in the second exhaust gas distribution component. The reducing agent decomposition system It also contains a reducing agent injector that is connected to the chamber for reducing agent injection with the fluid flowing through the chamber. Exhaust gas is coupled.

[0038] In a particular embodiment, which is shown in Fig. 1, an exhaust aftertreatment system 10 is equipped with a (not shown) The combustion engine is coupled and can receive and process the exhaust gas produced by the engine. In certain implementations, this is Exhaust aftertreatment system 10 is attached to a vehicle in which the engine is housed. The system 10 can be used Various fastening techniques and / or fastening devices can be attached at any different location on the vehicle. In the specific embodiment shown in Fig. 1, the exhaust aftertreatment system 10 is attached to a [vehicle / body] by means of brackets 14. Frame support 12 of a (not shown) vehicle is attached.

[0039] The exhaust aftertreatment system 10 comprises a first housing 20 and a second housing 30. The first housing 20 contains an exhaust gas inlet 22 and outlet 24 (see Fig. 2 and Fig. 3). Likewise, the second housing 30 contains an exhaust gas inlet 32 ​​and outlet. 34. The inlet 22 of the first housing 20 and the outlet 34 of the second housing 30 are located near the same end of the Exhaust aftertreatment system 10. Likewise, the outlet 24 of the first housing 20 and the inlet 32 ​​of the second housing 30 are located near the same end of the exhaust aftertreatment system 10. In certain implementations, the outlet 24 and the inlet 32 ​​are in the Essentially coplanar (see, for example, Fig. 5).

[0040] Both the first and the second housing 20 , 30 enclose and hold one or more exhaust gas treatment devices. fixed. Referring to Fig. 3, the first housing 20 encloses a diesel oxidation catalyst (DOC) 26 and a diesel particulate filter (DPF) 28 downstream of the diesel oxidation catalyst. The second housing 30 encloses a catalyst for selective catalytic reduction. (SCR catalyst) 36 and holds it in place and can furthermore include an ammonia oxidation catalyst 38 downstream of the SCR catalyst included. Although the first and second housings 20, 30 in the illustrated embodiment contain the respective exhaust gas treatment devices. 26, 28, 36, 38 in the order shown, enclose and hold; in other embodiments, the first and the second Enclosures can accommodate any number and any type of exhaust gas treatment devices in any number of different sequences. include, without deviating from the essence of the present invention. For example, the decomposition chamber 44 can be supplied with exhaust gas directly from a DOC. instead of being obtained from a DPF. However, the decomposition chamber 44 preferably always precedes an SCR catalyst.

[0041] The control of the exhaust aftertreatment system 10 is at least partially dependent on the state of the exhaust gas flowing through the system. dependent. Exhaust gas conditions can be detected using various sensors positioned throughout the system. Among the Conditions can affect the concentrations of NOx, CO, hydrocarbons, ammonia and other components of the exhaust gas, as well as the temperature. and the The throughput of the exhaust gas is measured. The sensors transmit detected conditions to a sensor module 16, which processes the signals received from the sensors. processed and / or the signals for initial or further processing to an (not shown) engine control module or similar The device transmits data. At least partially based on the detected exhaust gas conditions, the engine control module can determine engine parameters and / or... or control the exhaust aftertreatment system to reduce harmful emissions in the exhaust gas as desired.

[0042] The inlet 32 ​​of the second housing 30 is connected to the outlet 24 of the first housing 24 via a reducing agent decomposition system. 40 in exhaust gas receiving connection. The reducing agent decomposition system 40 includes an end cap 42, which is attached to an end plate 15 of the Mounting bracket 14 is attached, to which the outlet 24 and the inlet 32 ​​are attached. When attached to the end plate 15, the The inner surfaces of the end cap 42 and the end plate 15 together form a decomposition chamber 44. The end cap 42 is attached to a downstream The side of the end plate 15 is attached above the first and second openings 18, 19 (see, for example, Fig. 3 and Fig. 7). The downstream sides of the The first and second openings 18, 19 of the end plate 15 define an inlet 46 and an outlet 48 of the decomposition chamber 44. The first Housing 20 is attached to an upstream side of the end plate 15 above the first opening 18 formed in the end plate, and the second Housing 30 is attached to the upstream side of the end plate above the second opening 19 formed in the end plate. Accordingly, the upstream sides of the first and second openings 18, 19 of the end plate 15 have approximately the same extent as the outlet 24 of the first housing and the inlet 32 ​​of the second housing 30.

[0043] The end plate 15 and the end cap 42 are configured to form a specially dimensioned and shaped decomposition chamber 44 to define. As defined here, a chamber as defined here is an essentially enclosed space with an essentially non-enclosed space. cylindrical shape. Furthermore, a chamber as defined here, compared to conventional linear reducing agent decomposition lines, which are used in typical SCR systems and have an essentially tubular shape, essentially non-tubular. In general, the decomposition chamber 44 in one embodiment is a non-linear and asymmetric space located between the end plate 15 and the end cap 42 is defined. In the specifically illustrated embodiment shown in Fig. 3, the end cap 42 contains a substantially flat, closed upper wall 122, an open floor 124 opposite the upper wall and a side wall 126 located between the The upper wall extends to the open floor. Referring to Fig. 5, the side wall 126 extends over a curved edge 132, which extending around the upper circumference of the end cap 42, gradually transitioning into the upper wall 122. The edge 132 is curved to create a vortex motion. to facilitate the flow of exhaust gas into the decomposition chamber 44 and to reduce the space occupied by the end cap 42 to a minimum. Furthermore, in some embodiments, the decomposition chamber 44 has a flat profile, that is, a height that is significantly less than a Length or width is, on. Furthermore, the cross-sectional shape of the decomposition chamber 44, which is perpendicular to the axial length extending from the inlet 46, is The chamber extending to outlet 48 is defined as being essentially non-circular and asymmetrical.

[0044] The distance between the upper wall 122 and the open bottom 124 defines the height of the end cap 42 and thus the height of the Decomposition chamber 44. The height of the end cap 42 can be close to the first exhaust gas distribution component 60 compared to the height of the end cap near The second exhaust gas distribution component 70 is larger. As shown in Fig. 5, the height of the end cap 42 is close to the first exhaust gas distribution component. 60 large enough to allow exhaust gas to escape from first perforations 102 of a first perforation pattern 100 (see Fig. 4) without Unnecessary restriction of flow into chamber 44 and away from the first exhaust gas distribution component. Furthermore, the height of the end cap 42 near the second exhaust distribution component low enough to allow the end 78 of the contraction tube 72 to meet the end cap is attached. In some implementations, decomposition chamber 44 can be a decomposition chamber with adjustable geometry, where the The component or components that define the decomposition chamber are reconfigurable to change the volume of the decomposition chamber.

[0045] Referring to Fig. 7, the shape of the end cap 42 and the decomposition chamber 44 has a generally ovular shape in top view. In some implementations, the shape of the end cap 42 and the decomposition chamber 44 can be generally described as bean-shaped in top view. described such that the end cap includes a recess 136 to facilitate the attachment of a reducing agent injector 50 to the end cap. Both the upper end 128 and the lower end 130 of the end cap 42 are curved to conform to the shape of the first and second parts, respectively. to correspond to the second exhaust gas distribution component 60, 70. The curvature of the upper and lower ends 128, 130 facilitates the Vortex movement of exhaust gas in the decomposition chamber 44 and reduces the space occupied by the end cap 42.

[0046] The end cap 42 has a width defined between generally opposing sides 134 of the end cap. Opposite sides 134 extend between the upper and lower ends 128, 138. In some embodiments, the The width of the chamber 44 is between approximately 25% and 150% of the axial length of the chamber, which is defined as the distance between the inlet 46 and the outlet. 48 of the chamber is defined. Accordingly, chamber 44 has a significantly larger width-to-length ratio than conventional linear chambers. Reducing agent decomposition tubes used in conventional SCR systems.

[0047] Although, furthermore, the decomposition chamber 44 in the illustrated embodiments is separated by the end cap 42 and a The separate end plate 15 of the mounting bracket 14, to which the end cap is attached, is defined; in other embodiments, the Decomposition chamber defined by a separate casing or housing independent of the mounting bracket without deviating from the essence of the invention. In general, the decomposition chamber can be made from any number of different components. or structures are defined which, alone or in combination with each other, constitute a reducing agent decomposition volume or space as shown here can be described as having a single exhaust inlet and outlet or multiple exhaust inlets and outlets.

[0048] Referring to Fig. 1, the reducing agent decomposition system 40 includes a reducing agent injector 50, which is attached to the End cap 42 is attached. Although a single reducing agent injector 50 is shown, in other embodiments several are possible. Reducing agent injectors are used. The reducing agent injector 50 is available with a (not shown) reducing agent source, such as... Example of a container containing a reducing agent, in a reducing agent receiving connection and contains a nozzle through which the reducing agent is injected into the decomposition chamber. The end cap 42 contains an opening through which the nozzle of the reducing agent injector 50 can be inserted. can extend at least partially. In some implementations, the nozzle is essentially flush with the inner surface of the end cap 42. In other implementations, the nozzle extends a desired distance into the decomposition chamber 44, as long as the sprayed material... Reducing agent does not directly impact nearby metal surfaces and cause urea polymerization. The nozzle position relative to The chamber 44 is based at least partially on the penetration length of the reducing agent spray. In general, the reducing agent injector 50 and the nozzle is positioned so that the injected reducing agent does not land on an opposite or nearby surface. The injector 50 is attached to the end cap 42 in a predetermined orientation, so that the nozzle... The reducing agent is injected into chamber 44 in a predetermined direction. Although the reducing agent almost completely disintegrates into the exhaust gas after injection. As soon as the solution begins to disperse in different directions, the nozzle injects reducing agent in an initial injection direction in the The reducing agent is usually applied axially to the nozzle. Preferably, the reducing agent is urea; however, other reducing agents can also be used. Reducing agents, such as ammonium formate solutions, can be used. The reducing agent injector 50 can be one of several in the The technology used is that of known reducing agent injectors. Since the exhaust gas can reach extreme temperatures and conventional reducing agent injectors... Since they are heat-sensitive, in some embodiments the end cap 42 may contain insulation around the part of the end cap where the The reducing agent injector 50 is attached.

[0049] The reducing agent injector 50 can be positioned at any different locations around the end cap 42 to inject reducing agent to inject into the decomposition chamber 44. Alternatively, in some implementations, the reducing agent injector 50 can be positioned for this purpose and It can be configured to inject reducing agent directly into the contraction tube 72. Thanks to such a configuration, contact between the reducing agent and Metal surfaces are avoided, thus preventing the formation of reducing agent deposits on the surfaces.

[0050] Referring to Fig. 3, the reducing agent decomposition system 40 includes a first and a second exhaust gas distribution component. 60 or 70, which are arranged in the decomposition chamber 44. In general, the first exhaust gas distribution component 60 receives exhaust gas. from the first housing 20 and distributes the exhaust gas in a predetermined manner into the decomposition chamber 44. Similarly, the second exhaust gas distribution component 70 generally exhaust gas from the first distribution component 60 and distributes the exhaust gas into and from the second Exhaust gas distribution component in a predetermined manner. The first and second exhaust gas distribution components 60, 70 facilitate in conjunction with the size and the shape of the decomposition chamber 44 provides improved mixing of the reducing agent, a longer residence time for the reducing agent decomposition and a more uniform flow distribution at the inlet surface of an SCR catalyst compared to conventional linear exhaust pipes with of the same axial length as the chamber. Since the decomposition chamber 44 ensures the same or better decomposition performance Since it does not need to be as long as conventional reducing agent decomposition tubes, the reducing agent decomposition system can be more compact. and can occupy less volume than conventional reducing agent decomposition tubes, while achieving a similar residence time.

[0051] Referring to Fig. 4, the first exhaust gas distribution component 60 includes a perforated pipe 62 and a flange 64. The perforated tube 62 includes a side section 66, which extends from an open upstream end 67 to a partially closed end. The flange 64 extends substantially radially outwards from the open end 67 to the downstream end 68 (see Fig. 3). The flange 64 is attached to the end plate 15 of the mounting bracket 14 around the first opening 18, so that the first exhaust gas distribution component 60 effectively covers opening 18. In this way, all exhaust gases from the DPF 28 or any other various other The exhaust gas flows through the emission treatment devices and exits from the first housing 29 into the first exhaust gas distribution component 60. Under certain conditions... In this implementation, the upstream part of the flange 64 has the same dimensions as the opening 18. The perforated tube 62 can have a generally circular cross-section, as shown, or another cross-sectional shape as desired. Although this is not necessary, the cross-sectional area of ​​the perforated tube 62 is preferably only slightly smaller than the cross-sectional area of ​​the first housing outlet 24 .

[0052] The perforation tube 62 of the first distribution component 60 contains one or more perforations or openings that are located in one or The perforations are arranged in several patterns. Preferably, the perforated tube contains 62 perforations of different sizes and / or shapes. Each perforation pattern can have perforations of the same size and / or shape, or perforations of different sizes and / or shapes. contained. In the illustrated embodiment, the perforation tube 62 contains a first perforation pattern 100, which is formed in the end 68, a second perforation pattern 104, which is formed on page 66, and a third perforation pattern 108, which is also formed on page 66 Although three perforation patterns are shown, the perforated tube 62 can have more or fewer than three perforations in other embodiments. Perforation pattern included.

[0053] The first perforation pattern 100 contains several first perforations 102 which are distributed substantially evenly over the end 68. The first perforations 102 each have the same size and shape. As shown, each of the first perforations 102 has a general circular cross-section. Furthermore, the first perforations 102 are dimensioned and present in such a number that they define a first percentage of the open area of ​​the first perforation pattern 100.

[0054] The second perforation pattern 104 contains several second perforations 106 which are distributed substantially evenly over a portion of the side 66 are distributed. The second perforations 106 each have the same size and shape. As shown, each of the second perforations 106 a generally circular cross-section. Furthermore, the second perforations 106 are dimensioned and present in such a number, that they define a second percentage of open area of ​​the second perforation pattern 100.

[0055] The third perforation pattern 108 contains several third perforations 110 which are distributed substantially evenly over a portion of the side 66 are distributed. In the illustrated embodiment, the third perforation pattern 108 contains five perforations 110. The third perforations 110 They each have the same size and shape. As shown, each of the third perforations 110 has a generally ovular or racetrack-shaped shape. cross-section. In particular, the cross-sectional shape of the third perforations 110 has two spaced-apart parallel sides, which are defined by two curved sides are connected. The parallel sides of the third perforations 110 run essentially parallel to a central axis. of the perforation tube 62. The third perforations 110 are dimensioned and present in such a number that they constitute a third percentage. Define 100 on the open area of ​​the third perforation pattern.

[0056] The first, second and third percentage of open areas of the first, second and third perforation pattern respectively 100 , 104 , 108 They are chosen to achieve a desired flow profile through the decomposition chamber and to reduce exhaust back pressure. In the case of a In this embodiment, the second percentage of open area is greater than the first percentage of open area, and the third percentage of open area is greater than the third percentage of open area. open area greater than the second percent of open area. As described in more detail below, such a configuration promotes the Provision of a convective exhaust gas flow past the reducing agent injector 50, turbulent flow from the end 68 of the perforated tube and Reduced flow restriction to lower exhaust backpressure. In certain implementations, the first percentage of open area between approximately 10% and approximately 30%, the second percentage of open area between approximately 20% and 45%, and the third percentage of Open area between approximately 45% and 80%. In one specific implementation, the first percentage of open area is approximately 20%, the second... The percentage of open area is approximately 35%, and the third percentage of open area is approximately 50%. Although in the illustrated embodiment the the second percentage of open area is larger than the first percentage of open area, and the third percentage of open area is larger In other embodiments, the first percentage of open area can be larger than the second percentage of open area, as desired. be smaller than the second percentage of open area and the third percentage of open area be smaller than the first and / or the second open area area, without deviating from the idea of ​​the invention.

[0057] In general, the smaller the perforation size, the more homogeneous and isotropic the turbulent exhaust gas flow is immediately downstream. the perforation. As the size of the perforations increases, the exhaust gas throttling decreases, and the resulting exhaust gas flow rate increases. This results in the generation of more efficient convection flow profiles. A reducing agent is injected into the turbulent flow and mixed with the surrounding fluid. It deals with exhaust gases to a lesser extent, for example millimeters, than with convection currents, for example inches, because the Convective transport process in flow profiles with a higher average velocity compared to flow profiles with turbulent flow Fluctuations are improved. In other words, turbulent flow can have a much shorter mixing length than convection flow. Accordingly, In certain applications, it may be desirable to generate a circulating flow past the reducing agent injector nozzle, so that the initial mixing of the reducing agent with the exhaust gas via convection current is carried out quickly and efficiently. After the After initial mixing via convection current, it would be desirable to introduce the circulating current with turbulent current in order to... To further mix reducing agents with exhaust gas.

[0058] To generate an organized convection current past the reducing agent injector nozzle and a turbulent current downstream The second and third perforation patterns 100 and 108 of the nozzle are strategically placed on respective parts of side 66 of the perforation tube 62. positioned so that the exhaust gas leaves the perforations 106, 110 in a desired manner and direction. The smaller second Perforations 106 are configured to generate a turbulent flow immediately downstream of the perforations 106. The much larger The third perforations 110, however, are configured to allow an essentially convective flow around the circumference of the perforation tube 62. counterclockwise (see, for example, exhaust gas flow 94 in Fig. 7) as well as clockwise (see, for example, exhaust gas flow 96) to produce (in Fig. 7). The parts of page 66, on which the second and third perforation patterns 104, 108 are arranged, are based on the direction in which the perforations 106, 110 point with respect to the reduction agent injection direction of the injector nozzle. In general, the second perforations 106 of the second perforation pattern 104 to the reducing agent injector nozzle, that is, the second perforations point in a direction that forms an angle with the reduction agent injection direction that is less than or equal to approximately 90 degrees. The third perforations 110 The third perforation pattern 108, however, points away from the reducing agent injector nozzle, that is, the third perforations point in a Direction that forms an angle with the reduction agent injection direction that is greater than approximately 90 degrees.

[0059] The perforations of a particular pattern do not all have to be the same size and shape, as in the illustrated An embodiment is shown. Furthermore, the perforations of a pattern do not need to be evenly distributed over a surface. For example, In some embodiments, a perforation pattern can be used, with perforations of different sizes and different spacings between them. Perforations are included. In a specific implementation, the size of the perforations of the first perforation pattern can be radially adjusted. The inward direction gradually increases. In some implementations, the configurations of the perforation patterns can be selected accordingly. so that they achieve a desired acoustic effect.

[0060] Referring to Fig. 4 and Fig. 6, the second exhaust gas distribution component 70 includes a contraction tube 72 and a flange. 74 . The contraction tube 72 includes a side part 76, which extends from an open upstream end 77 (see Fig. 3 and Fig. 6) to a closed downstream end 78 extends. The flange 74 extends substantially radially outwards from the open End 77 gone. The flange 74 is attached to the end plate 15 of the mounting bracket 14 around the second opening 19, so that the second The exhaust gas distribution component 70 effectively covers the opening 19. In this way, all exhaust gas that comes from the first exhaust gas distribution component passes through. 60 and flows through the decomposition chamber 44 into the second exhaust gas distribution component 70. In certain implementations, the The furthest upstream part of the flange 74 has the same dimensions as the opening 18. To reduce vibrations in the The downstream end 78 of the contraction tube 72 can be attached to the end cap 42 of the second exhaust gas distribution component 70. In some In some cases, the downstream end 78 includes a projection or knob 79 to secure the downstream end to the end cap 78. to facilitate. In some implementations, the end cap 42 contains a corresponding recess to accommodate the button 79, which has a Snap connection, welding or other similar fastening mechanisms or techniques can be attached to the end cap.

[0061] The contraction tube 72 contains several elongated slots 112 and corresponding wings 114 that extend around a circumference of the tube. are positioned (see, for example, Fig. 6 and Fig. 8). In the illustrated embodiment, the slots 112 and wings 114 are located in a Line, for example, they extend longitudinally in a direction parallel to a central axis of the contraction tube 72 from a From a position near the open end 77 to a position near the closed end 78. In certain implementations, the slots extend 112 and the wings 114 over the entire length of the contraction tube 72, and in other implementations the slots and the wings extend only over part of the contraction tube 72. Although this is not necessary, the slots 112 and the wings 114 extend preferably over a substantial part of the length of the contraction tube 72. As shown in Fig. 6 for clarity, with the closed end removed. As shown at the end, in one embodiment each slot 112 between two adjacent wings 114 is defined. The number and size of the Slots 112 and wings 114 can be based on any one of several factors, such as a desired angular rotation rate of the exhaust gas in the pipe 72, manufacturing and material costs and exhaust gas flow resistance or throttling.

[0062] In the illustrated embodiment, part of the wing 114 extends beyond an outer surface 116 of the contraction tube 72. outwards, and part of each wing extends inwards over an inner surface 118 of the contraction tube 72. Each wing 114 is angled with respect to the outer and inner surfaces of the contraction tube 72 near each wing. In one implementation, the angle is based on the wing 114 on the distance between the open end 77 of the contraction tube 72 and the inlet surface 37 of the SCR catalyst 36 . Preferably, each wing 114 forms the same angle with respect to the surfaces of the contraction tube 72 near each wing. The wings 114 are configured to force exhaust gas to pass through the slots 112 at an angle with respect to a radial direction of the contraction tube as well as the contraction tube surfaces near each blade. As described in more detail below, the initial angling of the exhaust gas causes into the circular contraction tube 72, so that the exhaust gas is swirled in an interior space 120 of the contraction tube, which in some cases is This creates a swirling exhaust gas flow profile in the contraction tube.

[0063] Although the slots 112 and the wings 114 are identically shaped and aligned in the illustrated embodiments, they exhibit In other embodiments, the slots have different shapes and orientations relative to other slots, and some wings have different shapes and orientations with respect to other wings. Furthermore, slots 112 and wings 114 do not have to be parallel. extend longitudinally to a central axis of the contraction tube 76, but could extend at an angle to the central axis extend.

[0064] In some embodiments, the contraction tube 72 contains slots 112 formed in side 76, but does not contain extending from side 76, the wings 114 can be stationary fan blades located in the interior 120. of the contraction tube 72. In such an embodiment, exhaust gas exits in a direction substantially parallel to the radial direction. in the direction of travel into the slots 112. The exhaust gas then acts on the stationary fan blades in the contraction tube 72, which causes the This causes turbulence in the exhaust gas. In certain implementations, the contraction tube 72 can have slots 112 and vanes 114, as shown in Fig. 6. shown, as well as including a stationary fan blade positioned inside the pipe.

[0065] The contraction tube 72 can have a generally circular cross-section, as shown, or another cross-sectional shape as desired. exhibit. The cross-sectional area of ​​the contraction tube 72 can have any number of different sizes. In certain implementations The diameter of the contraction tube 72 is between approximately 30% and approximately 100% of the diameter of the outlet 48 of the decomposition chamber. In the illustrated embodiment, the diameter of the contraction tube 72 is approximately 55% of the diameter of the Chamber outlet 48 (see, for example, Fig. 7). As described in more detail below, the diameter of the contraction tube 72 influences the Power output of the second exhaust gas distribution component 70 .

[0066] Although the contraction tube 72 is used in an SCR system to remove exhaust gas, reducing agent and decomposed reducing agent To distribute the gas evenly over the inlet area of ​​an SCR catalyst, the contraction tube 72 can be used to direct any gas over the to distribute the inlet area of ​​any exhaust aftertreatment device evenly.

[0067] The various components of the exhaust aftertreatment system 10 can be made from any of the following materials as desired. Materials are manufactured. Most of the components are made from materials that can withstand high temperatures, such as metal. For example, steel and steel alloys. In certain implementations, for example, the first and the second housing 20, 30, the brackets 14 and the end cap 42, the first exhaust distribution component 60 and the second exhaust distribution component 70 made of steel or a steel alloy. The various components can be manufactured using any number of different methods. Devices, such as fastening mechanisms, and / or joining techniques, such as welding, which are known in engineering are connected to each other. In some embodiments, the reducing agent injector 50 is attached to the end cap via fastening elements. 42 attached. In some embodiments, the housings 20, 30 are welded to the mounting brackets 14, and the end cap 42 is attached to the End plate 15 is welded and the first and second exhaust distribution components 60, 70 are welded to the end plate.

[0068] Referring to Fig. 3, during operation the exhaust gas enters the inlet of the first housing at 80 and flows into an inlet of the DOC. 26. From the DOC 26, the exhaust gas flows at 82 through the inlet of the DPF 28. Exhaust gas flowing through the DPF 28 leaves the DPF and flows through the outlet 24 of the first housing 24, through the first opening 18 of the end plate 15, through the inlet 46 of the decomposition chamber 44 and at 84 into the first exhaust gas distribution component 84 .

[0069] After entering the first exhaust gas distribution component 84, a portion of the exhaust gas flows through the first perforation pattern 100 at 92. (see Fig. 5), part flows through the second perforation pattern 104 at 85 (see Fig. 7) and part flows through the third at 94, 96. Perforation pattern 108. The relative amounts of exhaust gas flowing through the respective patterns are based on the position and configuration of the Pattern. Due to the larger size of the third perforations 110, the throughput coming from the third perforations 110 is higher compared to The throughput from the smaller perforations 102 and 106 is proportionally higher. As shown in Fig. 7, a lower part of the The end cap 42 is shaped to correspond to the circumference of the perforated tube 62 and dimensioned to form a relatively narrow channel 52. provides a connection defined between the end cap and part of side 66 of the perforated tube. Channel 52 is configured to carry the current. to receive the relatively larger throughput from the third perforations 110 and to direct the convection current through the channel. Exhaust gas exiting from the perforations 110 of the upper third becomes a convection current through the channel in a counterclockwise direction. at 94 combined, and exhaust gas exiting from the perforations 110 of the lower third becomes a convection current through the channel in the Clockwise at 96 combined. The convective exhaust gas flow 94 leaves the channel 52 towards the nozzle of the reducing agent injector 50. , flows past the reducing agent injector nozzle, where it picks up injected reducing agent, and disperses, at least partially, to the second exhaust gas distribution component 70. The convective exhaust gas flow 96 leaves the channel 52 and disperses, at least partially, to the second Exhaust gas distribution component 70 .

[0070] The reducing agent decomposition system 40 is configured to pass exhaust gas through the decomposition chamber 44 into essentially non-reducible gases. to guide linear eddy current patterns. The exhaust gas flow 94, 96, facilitated by the third perforation pattern 108, drives the non-linear Eddy current patterns are at least partially present in chamber 44. During the dispersion of the convective exhaust gas flow 94, 96, current is applied. with comparatively lower throughputs from the second perforation pattern 104 at 85 the convection current to prevent mixing of the To improve the mixing of the reducing agent in the convection stream 94 with other exhaust gas in chamber 44. To further improve the mixing, A significant portion of the dispersed convection current 96 wraps around the perforated tube 62, strongly affecting and mixing with a significant portion of the dispersed convection current 94. In certain implementations, approximately 60% to approximately 80% of the convection current flows around the perforated tube 62. of the exhaust gas flowing into the perforated tube 62 through the openings 110 in the third perforation pattern 108. The combination of the Exhaust gas streams leaving the perforated tube 62 at 85, 92, 94, 96 mix at least partially and flow through the decomposition chamber. 44 to the second exhaust gas distribution component 70, as shown by the directional arrows 97. The flow 97 then swirls around the second Exhaust gas distribution component 70, as shown by the direction arrows 97, just before it enters the component through the slots 112.

[0071] The slots 112 and the vanes 114 are configured to generate an exhaust gas vortex in the contraction tube 72. When the exhaust gas As the flow passes through the slots 112, the wings 114 act in such a way as to direct the flow at 86 to the side 76 of the contraction tube 72 in a vortex profile. to redirect the exhaust gas along a central axis of the pipe. As the exhaust gas swirls, it moves slowly downwards in an axial direction and flows radially. inwards and downwards towards the central axis. Referring to Fig. 8, the swirling exhaust gas gains speed in a circular direction, which This means increasing angular rotation rate as it flows radially downwards until it reaches a maximum angular rotation rate. The local static The exhaust gas pressure is greatest at the point of maximum angular rotation rate. The reduced local static pressure leads to a reduction of the urea partial vapor pressure in the exhaust gas, which promotes evaporation and diffusion (for example, mixing) of the urea with the exhaust gas. Accordingly, the larger the maximum win The higher the rotational speed, the more intense the mixing of urea with the exhaust gas. Furthermore, the low-pressure point creates a vacuum effect to draw the urea away from the exhaust gas. radially outer part of the interior 120 to attract circulating exhaust gas radially.

[0072] Ideally, the exhaust gas reaches a maximum angular rotation rate at the central axis of the pipe 72. As shown in Fig. 8, the However, in some implementations, the exhaust gas exits at a radial location between side 76 of the contraction tube 72 and the central axis of the The pipe reaches a maximum rotational rate. From there, the rotational rate of the exhaust gas decreases as the exhaust gas continues to flow radially inwards. Fig. 8 shows a specific implementation with a rotation rate of approximately 47.20 m / s at a radially outermost part of the interior 120 of the Contraction tube 72 and a maximum rotation rate of approximately 74.70 m / s. It is understood that the number, size, and angle of the blades 114 can be designed and / or adjusted to achieve a desired vortex flow profile in the contraction tube 72. In the case of a In one embodiment, the contraction tube 72 can be a mixing device connected to a corresponding control system with adjustable or The blade geometry can be variable. The control system can be configured to adjust the blade geometry for different blade types. To request exhaust gas flow rates in order to optimize the distribution of the reducing agent over the area of ​​the SCR catalyst and / or to reduce mixing and to optimize the decomposition of the reducing agent.

[0073] The vortex profile of the exhaust gas in the contraction tube 72 effectively increases the distance that the exhaust gas has to travel with respect to the linear flow through a conventional exhaust pipe with the same axial length as the contraction pipe. Since the exhaust gas travels a longer distance The longer the distance the reducing agent has to travel, the longer the residence time for its decomposition to ammonia. Accordingly, the contraction tube improves 72 with a specific axial length, the decomposition of the reducing agent to ammonia compared to a conventional linear A tube of the same axial length. Besides improving the decomposition of the reducing agent to ammonia, this also improves the... The contraction tube 72 also generated a vortex profile, resulting in the mixing of the reducing agent and / or ammonia with the exhaust gas. Under certain conditions... Implementations decompose and mix the reducing agent decomposition system 40, which includes the contraction tube 72, the perforation tube 62 and the decomposition chamber 44 contains urea with exhaust gas, so that the uniformity index of the vapor, which is the molar number distribution of ammonia in the exhaust gas or the molar flow through the inlet of the SCR catalyst, is greater than approximately 0.90 at the inlet of the SCR catalyst 36 and The percentage of urea decomposition to ammonia is greater than approximately 90%. Therefore, the reducing agent decomposition chamber 44 can be used for this purpose. be configured to have an ammonia mixing and decomposition index (that is, vapor uniformity index multiplied by the percentage of decomposition). to achieve a conversion ratio (from urea to ammonia) of approximately 0.80.

[0074] The contraction tube 72 further offers the additional advantage of facilitating a more uniform exhaust gas flow distribution (the (meaning a larger flow distribution index) at the inlet surface 37 of the SCR catalyst 36. As discussed above, the blades 114 configured to redirect exhaust gas flow in a vortex profile outwards to side 76 of the contraction tube 72. Referring to Fig. 9, it holds The side 76 of the contraction tube 72 stabilizes the exhaust gas flow and directs it to the central axis of the tube. At a point near the open At the end 77 of the pipe, the exhaust gas flow entering the contraction pipe 72 through the slots 112 is held back by side 76, which directs the outwards flow. The exhaust gas flow is not fixed. As shown in Fig. 9, the exhaust gas flow continues to flow outwards at the open end 77 of the contraction tube. 72 and the space between the open end and the inlet surface 37 of the SCR catalyst. Conventional systems with linear Pipelines often lead to an exhaust gas concentration at an internal, central point on the inlet surface of the SCR catalyst. This is caused by... The blades 114 of the contraction tube 72 caused an outwardly directed exhaust gas flow, but directs the exhaust gas flow to the outer parts of the Inlet area 37, so that the exhaust gas is distributed more evenly at the inlet area. In some implementations, a contraction tube 72 is used with a larger diameter results in more exhaust gas being distributed to the outer parts of the inlet area 37 of the SCR catalyst 36, and thus to a larger exhaust gas flow distribution index at the inlet area.

[0075] After exiting the second exhaust gas distribution component 70, the exhaust gas flows through the SCR catalyst 36 at 88 and the Ammonia oxidation catalyst 38 after flowing through the outlet 48 of the decomposition chamber 44, the second opening 19, the second Housing inlet 32 ​​and the SCR catalyst inlet surface 37. The exhaust gas then exits the second housing 30 at 90° through outlet 24. out, after it has passed through the ammonia oxidation catalyst 38.

[0076] According to an embodiment shown in Fig. 10, a method 200 for decomposing urea to ammonia at 210 comprises Guiding exhaust gas through a perforation pattern and into a chamber. The perforation pattern can consist of one or more perforations, for example, to... For example, the perforation patterns 100, 104, 108, which together at 220 causes turbulence of the exhaust gas in the chamber, thereby extending the residence time of the system. The exhaust gas turbulence flow in the chamber The cumulative effect of a first, faster current generated by an initial perforation pattern of large perforations (for example, convection current), a second, slower current (for example, convection current) generated by the first perforation pattern, one generated by A second perforation pattern with smaller perforations generated a first, slower current, and one through a third perforation pattern. The generated second, slower current. The perforation patterns can be found in a perforated tube in exhaust gas receiving connection with a The outlet of an exhaust aftertreatment component, such as a DPF, must be designed accordingly. Furthermore, the procedure comprises 200 at 230, a reducing agent, for example urea, is injected into the exhaust gas swirling in the chamber, and at 240, the mixture is mixed. Urea with the exhaust gas. Furthermore, the process includes, at 250 degrees, the extraction of exhaust gas from the chamber between several vanes, to For example, the vanes 114 are used to further swirl the exhaust gas in the chamber. Preferably, the exhaust gas is guided between the vanes. an eddy current pattern, that is, a vortex. The vanes can be part of a contraction tube in an exhaust gas supply connection with an inlet of the This could be an exhaust aftertreatment component, such as an SCR catalyst. Furthermore, the process can include directing the exhaust flow radially outwards to an SCR catalyst after it has passed through several vanes.

[0077] The present invention can also be designed in other specific forms without deviating from its concept or its to deviate from essential features. The described embodiments are intended in every respect to be illustrative only and not as The scope of protection of the invention is therefore defined by the appended claims, rather than by the preceding claim. Description displayed. All changes that fall within the scope and equivalence of the claims shall be distinguished from their The protected area must be included.

Claims

[1] Reducing agent decomposition system, comprising: an exhaust chamber that has an inlet and an outlet; a first exhaust gas distribution component that is positioned in the chamber and can be brought into exhaust gas receiving communication with the inlet, wherein the first exhaust gas distribution component is configured to create swirl exhaust gas flow profiles in the exhaust chamber; a second exhaust gas distribution component that is positioned in the chamber and can be brought into exhaust gas supply connection with the outlet, wherein the second exhaust gas distribution component is configured to create a swirl exhaust gas flow profile in the second exhaust gas distribution component; and a reducing agent injector coupled to the exhaust gas chamber, wherein the reducing agent injector is in contact with the exhaust gas in the chamber It can be brought into a reducing agent injection connection. [2] Reducing agent decomposition system according to claim 1, wherein the inlet and outlet of the exhaust chamber are substantially coplanar and / or wherein the exhaust chamber has a width and a length, wherein the width is at least approximately 0.25 times the length and / or wherein a reducing agent decomposition length of the exhaust aftertreatment system greater than an axial length between the inlet and the outlet of the It is the exhaust chamber. [3] Reducing agent decomposition system according to claim 1 or 2, wherein the first exhaust gas distribution component comprises a first set of small perforations and a second set of large perforations, wherein the small perforations of the first set are to the facing the reducing agent injector and the large perforations of the second set facing away from the reducing agent injector, with the first The first set of small perforations is preferably configured to generate turbulent exhaust flow, and the second set of large perforations is configured to generate an essentially convective exhaust gas flow. [4] Reducing agent decomposition system according to one of the preceding claims, characterized in that the first Exhaust gas distribution component: a perforated pipe with a first open end, a second partially closed end, and a section extending between The side wall extends from the first open end to the second closed end, and the perforated tube comprises several The perforations are formed in the side wall and in the partially closed end, with the multiple perforations forming a first set of perforations formed in the second partially closed end, a second set of perforations formed in a first part of the side wall, and a third set of perforations formed in a second part of the side wall, contained, wherein the first set of perforations defines a first percentage of open area, the second set of perforations a second percentage of open area defined and the third set of perforations defines a third percentage of open area, and wherein second pro The percentage of open space is greater than the first percentage of open space, and the third percentage of open space is greater than the second. Percentage of open area. [5] Reducing agent decomposition system according to one of the preceding claims, characterized in that The second exhaust gas distribution component has several vanes and corresponding slots that create an exhaust gas vortex in the second The exhaust gas distribution component is configured, comprising the second exhaust gas distribution component preferably a contraction pipe with an open comprising an end, a closed end and a side wall extending between the open and the closed end, wherein the several wings and slots extend longitudinally along at least part of the side wall, wherein each of the multiple wings is preferably angled with respect to the side wall at a point near each wing, and wherein each wing extends outwards from an outer surface of the side wall and inwards from an inner surface of the side wall, wherein furthermore preferably the angle formed between each of the several wings and the side wall at the point near each wing a distance between the open end of the contraction pipe and an exhaust aftertreatment device downstream of the open end of the Contraction tube based. [6] Reducing agent decomposition system according to one of the preceding claims, characterized in that a height of the exhaust gas chamber The height of the exhaust chamber near the first exhaust distribution component is greater than the height of the exhaust chamber near the second exhaust distribution component. [7] Exhaust aftertreatment system, comprising: a diesel particulate filter through which exhaust gas flows in a first direction, a catalyst for selective catalytic reduction, through which exhaust gas flows in a second direction, essentially the same as the first direction is the opposite; a urea decomposition chamber which has an inlet that can be connected to the diesel particulate filter in exhaust gas receiving communication, and includes an outlet that can be connected to the exhaust gas supply system with the catalyst for selective catalytic reduction, wherein the urea decomposition chamber has a non-cylindrical and non-linear shape, and wherein the urea decomposition chamber Turbulent exhaust gas flow profiles in the urea decomposition chamber are facilitated; and a urea injector coupled to the urea decomposition chamber, wherein the urea injector is supplied with exhaust gas in the The urea decomposition chamber can be brought into the urea injection connection. [8] Exhaust aftertreatment system according to claim 7, further comprising an exhaust gas distribution component located in the urea decomposition chamber is positioned and can be brought into exhaust gas receiving communication with the inlet of the urea decomposition chamber, whereby the Exhaust distribution component a first set of perforations, each having a first surface, and a second set of perforations, each containing a second surface, the first surface being significantly larger than the second surface, and / or further comprising an exhaust gas distribution component that is positioned in the urea decomposition chamber and connected to the outlet of the urea decomposition chamber in exhaust gas supply connection, whereby the exhaust gas distribution component may contain several vanes configured to... To swirl the exhaust gas in the exhaust gas distribution component. [9] Exhaust aftertreatment system according to claim 7 or 8, wherein a form of the urea decomposition chamber is defined by a height, length and width is defined where the length is greater than the width and height, and the width is greater than the height, and / or where a cross-sectional shape of the Urea decomposition chamber along a plane extending perpendicular to the first and second exhaust gas flow directions, a first curved part extending around the inlet, and a second curved part extending around the outlet, and exhaust gas from the diesel particulate filter from the inlet to the outlet of the urea decomposition chamber, wherein preferably the first and the second The curved part promotes turbulence of exhaust gas in the urea decomposition chamber. [10] Process for the decomposition of urea to ammonia, comprising: Guiding exhaust gas through a perforation pattern and into a chamber, the perforation pattern causing turbulence of the exhaust gas in the chamber This causes; injection of urea into the exhaust gas in the chamber; and Guiding exhaust gas in the chamber between several vanes to further swirl the exhaust gas in the chamber. [11] Method according to claim 10, wherein the perforation pattern has several first perforations, each having a first size, and several second perforations, each having a a second size that is larger than the first size includes, where directing exhaust gas through a perforation pattern includes directing exhaust gas through the first and second perforations, and / or where exhaust gas is directed into the chamber between the The multiple blades cause the exhaust gas to swirl before it flows between the multiple blades and after it flows between the multiple blades. Wings flow, and / or wherein the multiple wings are positioned around a central axis, the method continuing to direct a portion of the exhaust gas radially inwards the central axis includes the flow of exhaust gas between the multiple vanes, and preferably further directs a portion of the exhaust gas. radially outwards from the central axis, guiding the exhaust gas between the multiple wings.

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