Device for exhaust gas aftertreatment of combustion gases

Abstract

The present disclosure proposes an apparatus for exhaust aftertreatment of an internal combustion engine, comprising: an exhaust line connected to an outlet of the internal combustion engine; an additive injection device for introducing an additive into the exhaust line; a catalyst located within the exhaust line and arranged downstream of the additive injection device; and a combustor having at least one exhaust line system; wherein the exhaust line between the injection point of the additive and the catalyst has: a first gas mixing zone located in a first line section, an NH3 mixing zone located in a second line section, and a further gas mixing zone located in a third line section; the exhaust line system has at least two outlets arranged and configured such that it can introduce exhaust gases of the combustor into at least two of the following sections: the first, second and third line sections. With the apparatus for exhaust aftertreatment provided by the present disclosure, the way of introducing combustor gases into the exhaust is improved, thereby achieving a better heat distribution in the exhaust.

Description

Technical Field

[0001] This disclosure relates to an apparatus and method for exhaust aftertreatment of combustion gases, particularly combustion gases from internal combustion engines. Background Technology

[0002] It is known in the art to treat combustion gases before they are released into the environment in order to reduce various pollutants.

[0003] In the exhaust systems of modern internal combustion engines, various exhaust aftertreatment devices are employed. For example, for internal combustion engines operating on diesel fuel, it is known to inject additives (such as urea) into the exhaust stream so that nitrogen oxides (NOx) can subsequently be removed in a catalytic converter (i.e., a catalytic converter), typically an SCR catalytic converter (SCR = Selective Catalytic Reduction). x It is reduced to non-harmful substances (CO2, H2O, N2). Alternatively, other catalysts and filters can be used, such as diesel oxidation catalysts (DOC = Diesel Oxidation Catalyst) or diesel particulate filters (DPF). DPFs are also frequently integrated into SCR catalysts.

[0004] Under certain engine operating conditions, especially shortly after engine start-up, the corresponding components of the exhaust or aftertreatment system may not reach sufficiently high temperatures to operate efficiently. In particular, SCR catalytic converters typically require a minimum exhaust temperature to function properly. Therefore, a combustor can be provided, for example, to introduce additional hot gases into the exhaust stream upstream of the catalytic converter, thereby heating the catalytic converter to the appropriate temperature more quickly. In known combustors, hot combustor gases are introduced into the exhaust pipe at a predetermined location upstream of the catalytic converter. Various problems have arisen in this process. One problem is the formation of localized hot spots, which may be due to insufficient mixing of combustor gases and exhaust. On the one hand, this can lead to damage to the catalytic converter; on the other hand, insufficient heat is available for catalytic decomposition at other locations.

[0005] Therefore, it would be advantageous to improve the way combustor gas is introduced into the exhaust gas, thereby achieving better heat distribution in the exhaust gas. Utility Model Content

[0006] According to this disclosure, an exhaust aftertreatment apparatus for an internal combustion engine is provided according to claim 1.

[0007] The exhaust aftertreatment device for an internal combustion engine includes: an exhaust pipe connected to the outlet of the internal combustion engine; an additive injection device for introducing an additive containing or capable of forming NH3 into the exhaust pipe; a catalyst located within the exhaust pipe and arranged downstream of the additive injection device; and a combustor having at least one exhaust pipe system. Preferably, the exhaust pipe sequentially includes, between the additive injection point and the catalyst, a first gas mixing zone in a first pipe section, an NH3 mixing zone preferably composed of a mixer in a second pipe section, and another gas mixing zone in a third pipe section; and the exhaust pipe system has at least two outlets arranged and configured such that they can introduce exhaust gas from the combustor into one or more sections: the first pipe section, the second pipe section, and the third pipe section. By separately introducing the exhaust gas into the combustor, the exhaust gas / additive / combustor exhaust gas mixture can be homogenized, and heat can be provided specifically for different processes, such as liquid evaporation, pyrolysis, hydrolysis, and / or catalyst heating.

[0008] Preferably, the exhaust piping system has at least one outlet arranged and configured to introduce combustor exhaust gas into at least a third piping section to ensure adequate heating of the catalyst and, if necessary, to support reactions that have not yet been completed between the exhaust gas and the additive.

[0009] In one embodiment, the exhaust piping system includes: a first outlet arranged and configured to introduce burner exhaust into a first piping section; a second outlet arranged and configured to introduce burner exhaust into a second piping section; and a third outlet arranged and configured to introduce burner exhaust into a third piping section. In this way, the required heat can be provided to each section in a targeted manner.

[0010] The exhaust piping system may also include a second outlet arranged and configured to introduce combustor exhaust upstream of the additive injection point into the internal combustion engine's exhaust piping. This raises the exhaust temperature upstream of the additive injection point, bringing the operating conditions in that area closer to normal operating conditions. This second outlet should be located immediately upstream of the injection point. "Immediately upstream" here should be understood as meaning that there is only one piping section between the outlet and the injection point, without other components such as a diesel oxidation catalyst or turbocharger.

[0011] At least one outlet is arranged such that the exhaust gas from the burner is introduced against the flow direction of the exhaust gas from the internal combustion engine to promote turbulence, thereby achieving thorough mixing of the exhaust gas, additives, and burner exhaust gas. Here, "against the flow direction" refers to any angle between 180° (opposite) and 90° (perpendicular) to the main flow direction of the exhaust gas.

[0012] In one embodiment, the exhaust piping system includes a common conduit and branch conduits leading to individual conduit sections. Preferably, at least 70% (especially preferably at least 80%) of the length of the exhaust piping system is contained within the exhaust conduit to reduce heat loss.

[0013] The exhaust piping system may include: a common pipe extending into a first piping section, and at least one branch pipe branching from the common pipe extending into a second and / or third piping section, and / or having corresponding outlet openings toward the second and / or third piping section. The exhaust piping system may also include: a common pipe extending into a second piping section, and at least one branch pipe branching from the common pipe extending into the first and / or third piping section, and / or having corresponding outlet openings toward the first and / or third piping section. Alternatively, the exhaust piping system may include: a common pipe extending into a third piping section, and at least one branch pipe branching from the common pipe extending into the first and / or second piping section, and / or having corresponding outlet openings toward the first and / or second piping section. In these designs that extend the common pipe into a piping section, the common pipe or one of the branch pipes must have at least one outlet within the corresponding piping section. The statement "the outlet opening faces a certain pipeline section" can be understood as meaning that the design of the outlet opening must ensure that the exhaust gas from the burner exiting from it mainly enters the corresponding pipeline section without interacting with the exhaust gas in other pipeline sections beforehand. Here, "mainly" can be understood as at least 50% (preferably at least 70%, and especially 90%) of the exhaust gas enters the pipeline section it faces without interacting with other gases.

[0014] The exhaust gas aftertreatment apparatus provided by the embodiments of this disclosure improves the way burner gas is introduced into the exhaust gas, thereby achieving better heat distribution in the exhaust gas.

[0015] Those skilled in the art will understand more application areas of this utility model through the following description. The description and specific embodiments in this utility model are for illustrative purposes only and do not constitute a limitation on the scope of protection of this disclosure. Attached Figure Description

[0016] The accompanying drawings described herein are for illustrative purposes only and not for all possible embodiments. These drawings do not constitute a limitation on the scope of this disclosure. In the drawings: Figure 1 This is a schematic diagram of an engine and an exhaust aftertreatment system based on the principles of this disclosure; Figure 2 This is a partial schematic diagram of an exhaust pipe according to the present disclosure, which includes a supply line to the catalytic converter and a combustor gas inlet line; Figure 3 yes Figure 2 The diagram shows a partial view of the exhaust pipe, wherein the burner gas inlet pipe adopts another embodiment described in this disclosure; Figure 4 yes Figure 2 The diagram shows a partial view of the exhaust pipe, wherein the burner gas inlet pipe adopts another embodiment described in this disclosure; Figure 5 yes Figure 2 The diagram shows a partial view of the exhaust pipe, wherein the burner gas inlet pipe adopts another embodiment described in this disclosure; Figure 6 yes Figure 2 The diagram shows a partial view of the exhaust pipe, wherein the burner gas inlet pipe adopts another embodiment described in this disclosure. Detailed Implementation

[0017] In this specification, the terms "up," "down," "right," and "left," as well as similar designations, refer to the orientations or arrangements shown in the figures and are used solely for describing embodiments. These terms may indicate preferred arrangements but should not be construed as limiting.

[0018] In addition, the terms “basically,” “about,” “around,” and similar terms mean: a range of deviations of + / - 10% (preferably + / - 5%) from the specified value.

[0019] In the following description, unless otherwise stated, the same reference numerals are used to refer to the same or similar elements in different embodiments.

[0020] Figure 1A schematic diagram of an internal combustion engine 1 with an exhaust aftertreatment system 3 according to a first embodiment of the present disclosure is shown. The internal combustion engine 1 is shown in a simplified form as a three-cylinder engine with an exhaust manifold 5 connected to the exhaust aftertreatment system 3. Of course, the internal combustion engine 1 may also have a different number of cylinders connected to the exhaust manifold 5. Furthermore, other types of engines may be used, such as a Wankel engine or other engines with exhaust lines, especially an exhaust manifold. The illustrated internal combustion engine 1 is a diesel engine, but other types of engines may also be used.

[0021] The exhaust aftertreatment system 3 includes a main exhaust passage 7 and a heating system 8 connected to the exhaust passage. The main exhaust passage 7 includes an exhaust pipe 9, a catalyst 10, and an additive injection device 11, the exhaust pipe 9 being connected to the exhaust manifold 5. Additionally, the exhaust pipe optionally includes a turbocharger 12, an oxidation catalyst 14 (DOC = (Diesel Oxidation Catalyst)), and a diesel particulate filter (not shown). The diesel particulate filter can, for example, be integrated into the catalyst 10.

[0022] From the exhaust manifold 5 to the catalyst 10, the following components are arranged sequentially on or in the exhaust pipe 9 or connected to the exhaust pipe 9: optional turbocharger 12, optional oxidation catalyst 14, additive injection device 11, and heating system 8.

[0023] In the embodiment shown in the figure, applicable to a diesel engine, the catalytic converter 10 is, for example, an SCR catalytic converter. However, other suitable types of catalytic converters may also be used, as long as they require a specific operating temperature to achieve efficient exhaust-additive aftertreatment. The catalytic converter 10 may be equipped with a temperature measurement unit 17 for detecting its own temperature. Such catalytic converters 10 are known in the art and therefore are not described in more detail.

[0024] The additive injection device 11 is a unit suitable for injecting additives into the aforementioned diesel engine, specifically by injecting diesel exhaust fluid (DEF, such as urea solution) into the exhaust manifold 9 upstream of the catalyst 10. For the following description, it is assumed that a urea solution (composed of water and urea) is used as the additive. However, other additives can also be injected, especially those containing or capable of generating NH3, which enable subsequent exhaust catalytic conversion. Such additive injection devices 11 are known in the art and therefore are not described in more detail.

[0025] The heating system 8 includes a burner 20 and an exhaust piping system 24. The burner 20 has supply lines 21 and 22 for supplying air and fuel. The exhaust piping system 24 is connected to an exhaust line between the additive injection device 11 and the catalyst 10. Alternatively, a single supply line can be provided to supply the air / fuel mixture. The burner 20, operating with air and fuel, is known in the art and therefore will not be described in more detail. The core focus here is the exhaust piping system 24, through which the burner's exhaust gas is directed into the exhaust line 9, the details of which will be further elaborated below.

[0026] Now we will combine Figures 2 to 6 The following describes in more detail the portion of the exhaust pipe 9 between the additive injection device 11 and the catalyst 10, as well as different embodiments of the exhaust pipe system 24. The section of the exhaust pipe 9 between the additive injection device 11 (or its additive inlet point in the exhaust pipe) and the catalyst 10 constitutes a hydrolysis section for the urea solution, and as... Figures 2 to 6 As shown, it can be roughly divided into three regions: a first gas mixing zone A, an NH3 mixing zone B (when using urea solution) preferably equipped with a mixer (not shown), and another gas mixing zone C. All types of mixers are known in the art and will not be described in detail herein.

[0027] In the first gas mixing zone A, the main processes involve mixing of the exhaust gas with the injected urea solution, partial evaporation of water from the urea solution, and potential pyrolysis of the urea solution to produce ammonia (NH3) and isocyanate. In the NH3 mixing zone B, the main processes involve further mixing of the exhaust gas with water vapor, pyrolysis of urea to produce ammonia (NH3) and isocyanate, and hydrolysis of the isocyanate, which reacts with water vapor to produce more ammonia and carbon dioxide. To facilitate this process, a mixer can be provided, as is known in the art. The generated NH3 is mixed with the exhaust gas. In another gas mixing zone C, the main process involves further mixing of the current gaseous products. Those skilled in the art will understand that these zones are not fixed, and mixing, water evaporation, pyrolysis, and hydrolysis processes may occur in each zone, but these processes are primarily concentrated in their respective zones. At the end of the gas mixing zone C, preferably, complete conversion of the urea solution is achieved, and the exhaust gas mixture should form a homogeneous mixture with sufficient temperature for subsequent catalytic reactions. Figures 2 to 6 In the diagram, the lengths of each region are roughly the same, but this is only a representation of the drawing and does not represent the actual structural proportions.

[0028] Both the evaporation and pyrolysis of water are endothermic processes, while hydrolysis is an exothermic process. However, in general, the exhaust gas is cooled in the hydrolysis section before entering the catalyst 10, and the catalyst 10 needs to be in a high-temperature environment when it performs the catalytic reduction reaction of nitrogen oxides (for example, the temperature needs to be >250℃ for standard SCR or the temperature needs to be maintained at 170℃-300℃ for fast SCR).

[0029] like Figure 2 As shown, the exhaust piping system 24 has a common pipe 26 at the outlet of the burner 20, which then branches into branch pipes 27 to 29. Branch pipes 27 to 29 all extend from the common pipe 26 to their respective outlets, and these outlets are all connected to the exhaust piping 9. Specifically, the outlet of branch pipe 27 leads to gas mixing zone A, the outlet of branch pipe 28 leads to NH3 mixing zone B, and the outlet of branch pipe 29 leads to another gas mixing zone C. Although the figure shows each outlet connected to its corresponding zone approximately at the center of the longitudinal direction of the exhaust piping 9, these outlets can actually be located at other locations within the corresponding zones, particularly at the beginning of each zone. In each of the branch pipes 27 to 29, a fixed or adjustable throttle valve (not shown) can be installed in the outlet zone or upstream of the outlet to adjust the exhaust flow rate through the branch pipes 27 to 29 accordingly. The outlets of branch pipes 27-29 are all arranged in a specific manner to ensure that the gas flowing out of the outlet is substantially perpendicular to the main flow direction of the exhaust in the exhaust pipe. However, the outlets can also be arranged along the main flow direction of the exhaust, against the main flow direction, or at a certain angle to the main flow direction.

[0030] Therefore, the hot exhaust gas generated by the burner can be introduced into the hydrolysis section of the exhaust pipe 9 at different points (areas) through the exhaust pipe system 24. Although Figure 2 The illustrated embodiment includes three branch pipes 27 to 29 with corresponding outlets, but in practice, only two of the branch pipes 27 to 29 may be provided to introduce the hot exhaust gas from the burner into the hydrolysis section of the exhaust pipe 9 at different locations. In this way, the energy required for evaporation / pyrolysis / hydrolysis and catalyst heating can be more targeted into the exhaust stream to ensure the most complete possible conversion of additives (e.g., urea solution) and subsequent catalytic conversion (e.g., reduction) of exhaust components (e.g., nitrogen oxides) when the energy input through the exhaust is insufficient (e.g., during restart, uphill driving, or start-stop operations).

[0031] In such Figure 2 In the embodiment shown, branch pipes 27 to 29 are mainly located outside the exhaust pipe 9 and only their ends extend into the exhaust pipe 9 to lead to the corresponding area.

[0032] like Figure 3 The exhaust piping system 24 shown has the same characteristics as... Figure 2 The common conduit 26 and branch conduits 27 to 29 shown have the same basic structure. However, in this embodiment, the common conduit extends into the exhaust conduit 9, and the branch conduits 27 to 29 extend within the exhaust conduit 9 to the corresponding zones A to C to provide access to those zones. This structure may reduce energy loss.

[0033] like Figure 4 The exhaust piping system 24 shown also has a common pipe 26 at the outlet of the burner 20, which then branches into branch pipes 27 to 29. In addition, there is another branch pipe 30 in the system, but this other branch pipe 30 can also be regarded as part of the common pipe 26 because it extends in a straight line to the common pipe 26 as a continuation of the common pipe 26.

[0034] Burner 20 in Figure 2 and Figure 3 In this embodiment, the burner 20 is arranged approximately in the center of the hydrolysis section (below NH3 mixing zone B), while the burner 20 is located in... Figure 4 In this embodiment, it is arranged below the first gas mixing zone A. A common conduit 26 extends into the gas mixing zone A. An additional branch conduit 30 extends the common conduit 26 through the gas mixing zone A and has an outlet that leads upstream of the gas mixing zone A to the exhaust conduit 9.

[0035] The outlet is oriented against the normal flow direction of exhaust gas within exhaust pipe 9, which causes turbulence in the exhaust gas. In another branch pipe 30, a fixed or adjustable throttle valve (not shown in the figure) can be installed at the outlet or upstream of the outlet.

[0036] Branch pipes 27 to 29 extend from the common pipe 26 in the region of the first gas mixing zone A, and the outlets of the branch pipes 27 to 29 lead to the corresponding zones A to C. Each of the branch pipes 27 to 29 extends substantially along the main flow direction of the exhaust gas in the hydrolysis section, such that the exhaust gas discharged from the burner 20 flows out from the branch pipes 27 to 29 in the main flow direction.

[0037] like Figure 5 The exhaust piping system 24 shown also has a common pipe 26 at the outlet of the burner 20, which then branches into branch pipes 27 to 29.

[0038] In this embodiment, the burner 20 is also arranged below the NH3 mixing zone B. A common conduit 26 extends into the NH3 mixing zone B. A branch conduit 27 extends from the common conduit 26 toward the first gas mixing zone A (i.e., against the normal flow direction of the exhaust gas in the exhaust conduit 9). The outlet of the branch conduit 27 leads to the first gas mixing zone A, and the gas exiting from this outlet flows against the main flow direction of the exhaust gas in the exhaust conduit 9, which causes turbulence. A branch conduit 28 is an extension of the common conduit 26, and its outlet leads to the NH3 mixing zone B. The orientation of this outlet is perpendicular to the normal flow direction of the exhaust gas in the exhaust conduit 9, which causes turbulence in the exhaust gas. Alternatively, the branch conduit 28 may also extend from the common conduit 26 along or against the normal flow direction of the exhaust gas and lead to the NH3 mixing zone B. A branch conduit 29 extends from the common conduit 26 toward another gas mixing zone C (i.e., along the normal flow direction of the exhaust gas in the exhaust conduit 9). The outlet of branch pipe 29 leads to another gas mixing zone C, and the gas discharged from this outlet flows out along the main flow direction of the exhaust in exhaust pipe 9.

[0039] like Figure 6 The exhaust piping system 24 also has a common pipe 26 at the outlet of the burner 20, which then branches into branch pipes 27 to 29.

[0040] exist Figure 6 In the illustrated embodiment, burner 20 is arranged below another gas mixing zone C. A common conduit 26 extends into gas mixing zone C. A branch conduit 27 extends from the common conduit 26 toward the first gas mixing zone A (i.e., against the normal flow direction of the exhaust gas in exhaust conduit 9). The outlet of branch conduit 27 leads to the first gas mixing zone A, and the gas discharged from this outlet flows against the main flow direction of the exhaust gas in exhaust conduit 9, which causes turbulence. A branch conduit 28 extends from the common conduit 26 toward the NH3 mixing zone B (i.e., against the normal flow direction of the exhaust gas in exhaust conduit 9). The outlet of branch conduit 28 leads to the NH3 mixing zone B, and the gas discharged from there flows against the main flow direction of the exhaust gas in exhaust conduit 9, which causes turbulence. Branch conduit 29 is an extension of the common conduit 26, and its outlet leads to another gas mixing zone C. The orientation of this outlet is perpendicular to the normal flow direction of the exhaust gas in exhaust conduit 9, which causes turbulence in the exhaust gas. Alternatively, branch line 29 may extend from common line 26 in the normal flow direction of exhaust gas or against the normal flow direction of exhaust gas and lead to another gas mixing zone C.

[0041] This disclosure has been described through exemplary embodiments, but is not limited to the specific features of each embodiment. For example, Figures 4 to 6In the illustrated embodiment, the branch pipes can be made shorter than those shown in the figure and do not need to extend into the corresponding pipe section. However, the design and arrangement of the outlet opening should meet the following requirement: the exhaust gas discharged from the outlet should primarily enter the designated pipe section and interact with exhaust gas in other pipe sections first. Here, "primarily" can be understood as at least 50% (preferably at least 70%, and especially 90%) of the exhaust gas will not interact before entering the pipe section it is directed towards.

[0042] The features of each of the described embodiments can be freely combined and / or interchanged, provided they are compatible with each other. Similarly, individual features of the embodiments can be omitted unless absolutely necessary. Without departing from the concept of this utility model, those skilled in the art can easily conceive of various modifications and design forms, all of which are within the protection scope of this utility model.

Claims

1. An exhaust aftertreatment device for an internal combustion engine, comprising: An exhaust pipe, which is connected to the outlet of the internal combustion engine; An additive injection device is used to introduce an additive containing or capable of generating NH3 into the exhaust pipe. A catalyst, located within the exhaust manifold and arranged downstream of the additive injection device; as well as A burner having at least one exhaust piping system; The exhaust pipe, between the additive injection point and the catalyst, includes: a first gas mixing zone in a first pipe section, an NH3 mixing zone in a second pipe section, and another gas mixing zone in a third pipe section; and The exhaust piping system has at least two outlets, which are arranged and configured to introduce exhaust gas from the burner into at least two sections: a first piping section, a second piping section, and a third piping section.

2. The apparatus according to claim 1, wherein, The exhaust piping system has at least one outlet, which is arranged and configured to allow exhaust from the burner to be introduced into at least the third piping section.

3. The apparatus according to claim 1 or 2, wherein, The exhaust piping system includes: A first outlet, the first outlet being arranged and configured such that the first outlet can introduce exhaust gas from the burner into the first pipeline section; A second outlet, arranged and configured such that the second outlet can introduce exhaust gas from the burner into the second conduit section; and A third outlet is arranged and configured such that the third outlet can introduce the exhaust gas of the burner into the third pipeline section.

4. The apparatus according to claim 1 or 2, wherein, The exhaust piping system has another outlet, which is arranged and configured such that it can introduce the exhaust gas from the burner into the exhaust piping of the internal combustion engine upstream of the injection point of the additive.

5. The apparatus according to claim 1 or 2, wherein, At least one of the outlets is arranged such that the exhaust gas from the burner is introduced in the opposite direction to the exhaust gas flow of the internal combustion engine.

6. The apparatus according to claim 1 or 2, wherein, The exhaust piping system includes a common piping and branch piping leading to the respective piping sections.

7. The apparatus according to claim 1 or 2, wherein, At least 70% of the length of the exhaust piping system is arranged inside the exhaust piping.

8. The apparatus according to claim 1 or 2, wherein, The exhaust piping system includes: The public pipeline extending to the first pipeline section, and At least one branch pipe from the common pipe leads to the second pipe section and / or the third pipe section, and / or has a corresponding outlet opening toward the second pipe section and / or the third pipe section.

9. The apparatus according to claim 1 or 2, wherein, The exhaust piping system includes: The common pipeline extending into the second pipeline section, and At least one branch pipe from the common pipe leads to the first pipe section and / or the third pipe section, and / or has a corresponding outlet opening toward the first pipe section and / or the third pipe section.

10. The apparatus according to claim 1 or 2, wherein, The exhaust piping system includes: The common pipeline extending into the third pipeline section, and Branch pipes branching off from the common pipe to at least one of the first pipe section and / or the second pipe section, and / or having corresponding outlet openings toward the first pipe section and / or the second pipe section.

Images