An exhaust gas treatment system, method, and vehicle

Abstract

This application discloses an exhaust gas treatment system, method, and vehicle, relating to the field of engine aftertreatment technology. The exhaust gas treatment system includes a first treatment unit, a second treatment unit, a third treatment unit, and a control unit. The first treatment unit is adapted to communicate with the exhaust gas outlet of the engine. The second treatment unit is connected to the output of the first treatment unit and is used to convert hydrocarbons and carbon monoxide. The third treatment unit is connected to the output of the first treatment unit and is used to convert nitrogen oxides. The second and third treatment units can be selectively connected to the output of the first treatment unit to adapt to different engine operating states. Thus, depending on the specific operating state of the engine, the first treatment unit, in conjunction with the second or third treatment unit, efficiently treats gaseous pollutants in the exhaust gas, thereby achieving ultra-low emission control and meeting increasingly stringent emission regulations.

Description

Technical Field

[0001] This application belongs to the field of engine aftertreatment technology, specifically relating to an exhaust gas treatment system, method, and vehicle. Background Technology

[0002] With increasing global emphasis on sustainable development, reducing vehicle emissions is a crucial step towards achieving green transportation. Lean-burn technology not only reduces harmful emissions but also improves engine thermal efficiency and fuel economy. Among related technologies, the three-way catalytic converter (TWC) struggles to convert nitrogen oxides (NOx) in exhaust gas under lean-burn conditions, thus requiring a combined selective catalytic reduction (SCR) catalytic converter. In these technologies, ammonia is generated through urea decomposition, providing the ammonia reducing agent needed for NOx conversion in the SCR catalytic converter. However, urea is prone to crystallization, the injection strategy is complex, the injection system has numerous components, and it occupies a large space.

[0003] Currently, the relevant technologies are limited by the engine's operating conditions and cannot efficiently treat pollutants generated under different engine operating conditions, thus failing to achieve ultra-low emission control of exhaust gases. Summary of the Invention

[0004] This application aims to provide an exhaust gas treatment system, method, and vehicle that can solve the problem in related technologies that cannot efficiently treat pollutants generated under different engine operating conditions, thus failing to achieve ultra-low emission control of exhaust gases.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows:

[0006] In a first aspect, embodiments of this application propose an exhaust gas treatment system, comprising: a first treatment unit adapted to be connected to the exhaust gas outlet of an engine; a second treatment unit connected to the output terminal of the first treatment unit, the second treatment unit being used to treat hydrocarbons and carbon monoxide in the exhaust gas output by the first treatment unit; and a third treatment unit connected to the output terminal of the first treatment unit, the third treatment unit being used to treat nitrogen oxides in the exhaust gas output by the first treatment unit; the second treatment unit and the third treatment unit may be selectively connected to the output terminal of the first treatment unit to adapt to different operating states of the engine.

[0007] Optionally, it further includes a control unit, which is located at the output end of the first processing unit. The control unit is used to control the output end of the first processing unit to connect with the second processing unit, or to control the output end of the first processing unit to connect with the third processing unit, based on the operating state of the engine.

[0008] Optionally, the control unit includes a controller and a switch; the controller is electrically connected to the engine, the switch is connected to the controller, and the controller is used to control the opening and closing of the switch based on the operating state of the engine.

[0009] Optionally, the switching element includes a first control valve and a second control valve. The first control valve is located between the output end of the first processing unit and the second processing unit, and is used to control the on / off state between the first processing unit and the second processing unit. The second control valve is located between the output end of the first processing unit and the third processing unit, and is used to control the on / off state between the first processing unit and the third processing unit.

[0010] Optionally, the first processing unit includes a TWC catalyst and a first SCR catalyst, the TWC catalyst being adapted to be connected to the exhaust outlet of the engine, and the first SCR catalyst being connected to the output end of the TWC catalyst; the first SCR catalyst is used to store ammonia gas produced by the TWC catalyst and to treat nitrogen oxides in the engine exhaust gas.

[0011] Optionally, the TWC catalyst includes a first catalyst, which comprises at least palladium.

[0012] Optionally, the first processing unit further includes a first ASC catalyst, which is connected to the output of the first SCR catalyst, and the first ASC catalyst is used to process the ammonia gas discharged from the first SCR catalyst.

[0013] Optionally, the second processing unit includes a GOC catalyst, which is connected to the output of the first processing unit and is used to process hydrocarbons and carbon monoxide in the exhaust gas output by the first processing unit.

[0014] Optionally, the second processing unit further includes an oxygen replenishment device, which is located between the GOC catalyst and the output end of the first processing unit. The oxygen replenishment device is connected to the GOC catalyst and is used to replenish oxygen to the GOC catalyst.

[0015] Optionally, the GOC catalyst includes a first support and a second catalyst coating, the second catalyst coating being attached to the first support, and the second catalyst coating including at least one of platinum and palladium.

[0016] Optionally, the second catalyst coating further includes an oxygen storage material for storing oxygen.

[0017] Optionally, the third processing unit includes a second SCR catalyst, which is connected to the output of the first processing unit and is used to treat nitrogen oxides in the exhaust gas output by the first processing unit.

[0018] Optionally, the third processing unit further includes a second ASC catalyst, which is connected to the output of the second SCR catalyst, and the second ASC catalyst is used to process the ammonia gas discharged from the second SCR catalyst.

[0019] Optionally, both the first SCR catalyst and the second SCR catalyst in the first processing unit contain a third catalyst, and the total amount of the third catalyst in the first SCR catalyst is greater than the total amount of the third catalyst in the second SCR catalyst.

[0020] Secondly, embodiments of this application propose a method for treating exhaust gas using any of the aforementioned exhaust gas treatment systems, for treating engine exhaust gas. The engine's operating states include a rich combustion state and a lean combustion state. The method includes: when the engine is in the rich combustion state, the control unit controls the first processing unit to connect with the second processing unit, so that the first processing unit treats nitrogen oxides in the exhaust gas discharged by the engine, and the second processing unit treats hydrocarbons and carbon monoxide in the exhaust gas; when the engine is in the lean combustion state, the control unit controls the first processing unit to connect with the third processing unit, so that the first processing unit treats hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust gas discharged by the engine, and the third processing unit treats nitrogen oxides not treated by the first processing unit.

[0021] Secondly, embodiments of this application provide a vehicle including an exhaust gas treatment system as described in any of the preceding claims.

[0022] In embodiments of this application, the exhaust gas treatment system includes a first treatment unit, a second treatment unit, a third treatment unit, and a control unit. The first treatment unit is adapted to communicate with the exhaust gas outlet of the engine. The second treatment unit is connected to the output terminal of the first treatment unit and is used to convert hydrocarbons and carbon monoxide. The third treatment unit is connected to the output terminal of the first treatment unit and is used to convert nitrogen oxides. The second and third treatment units can be selectively connected to the output terminal of the first treatment unit to adapt to different engine operating states. This allows for targeted and efficient treatment of gaseous pollutants in the exhaust gas by coordinating the first and second treatment units, or by coordinating the first and third treatment units, according to the specific operating state of the engine, thereby achieving ultra-low emission control of exhaust gas to meet increasingly stringent emission regulations.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram of an exhaust gas treatment system according to an embodiment of this application;

[0026] Figure 2 This is a schematic diagram of an ASC catalyst according to an embodiment of this application.

[0027] Figure label:

[0028] 1: First processing unit; 11: TWC catalyst; 12: First SCR catalyst; 13: First ASC catalyst; 131: Second support; 132: Noble metal coating; 133: SCR catalyst coating;

[0029] 2: Second processing unit; 21: GOC catalyst; 22: Injection gas device; 3: Third processing unit; 31: Second SCR catalyst; 32: Second ASC catalyst; 4: Control unit; 41: Switch; 411: First control valve; 412: Second control valve; 5: Engine. Detailed Implementation

[0030] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0031] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0032] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] Before explaining the exhaust gas treatment system, method, and vehicle provided in the embodiments of this application, the application scenarios of the exhaust gas treatment system, method, and vehicle provided in the embodiments of this application will be specifically described:

[0035] With the increasing severity of environmental pollution, vehicle exhaust emissions have attracted growing attention, prompting the government to enact the stricter National VI emission standards (GB17691-2018). These standards specify emission limits for gaseous pollutants emitted by spark-ignition vehicles and their engines that use natural gas (NG) or liquefied petroleum gas (LPG) as fuel. The main gaseous pollutants include carbon monoxide (CO) and nitrogen oxides (NOx). X Gas emissions include hydrocarbons (HCs, such as total hydrocarbons (THC), non-methane hydrocarbons (NMHC), and methane (CH4)). Specifically, NO... X ≤460mg / kWh, CH4≤500mg / kWh, NMHC≤160mg / kWh, NH3≤10ppm, CO≤4000mg / kWh, etc.

[0036] Modern engines use electronic control units (ECUs) to adjust the ratio of fuel injection to air supply in real time to achieve optimal combustion. However, in actual operation, the types and proportions of gaseous pollutants generated by the engine differ between rich and lean combustion states. Exhaust gas treatment systems in related technologies cannot effectively treat the gaseous pollutants produced under different engine operating conditions, thus failing to achieve ultra-low emission control.

[0037] Therefore, this application provides an exhaust gas treatment system, method, and vehicle. The exhaust gas treatment system, method, and vehicle provided in this application will be described in detail below with reference to the accompanying drawings and specific embodiments and application scenarios.

[0038] like Figure 1 As shown, an exhaust gas treatment system according to some embodiments of this application includes a first treatment unit 1, a second treatment unit 2, and a third treatment unit 3. The first treatment unit 1 is adapted to communicate with the exhaust gas outlet of the engine 5. The second treatment unit 2 is connected to the output end of the first treatment unit 1 and is used to convert hydrocarbons (HC) and carbon monoxide (CO). The third treatment unit 3 is connected to the output end of the first treatment unit 1 and is used to convert nitrogen oxides (NO). X The second processing unit 2 and the third processing unit 3 can be selectively connected to the output of the first processing unit 1 to adapt to different operating states of the engine 5.

[0039] In this embodiment, based on the operating state of the engine 5, the output of the first processing unit 1 is connected to the second processing unit 2, or the output of the first processing unit 1 is connected to the third processing unit 3; thereby enabling the first processing unit 1 and the second processing unit 2 to work together to process the exhaust gas discharged from the engine 5, or the first processing unit 1 and the third processing unit 3 to work together to process the exhaust gas discharged from the engine 5. Specifically, in one operating state of the engine 5, the exhaust gas discharged from the output of the first processing unit 1 has a high content of hydrocarbons and carbon monoxide, and is then processed by the second processing unit 2; in another operating state of the engine 5, the exhaust gas discharged from the output of the first processing unit 1 has a high content of nitrogen oxides, and is then processed by the third processing unit 3; thus, the gaseous pollutants in the exhaust gas can be efficiently treated according to the specific operating state of the engine 5, thereby achieving ultra-low emission control of exhaust gas to meet increasingly stringent emission regulations.

[0040] It's important to explain that engines typically operate in two states: rich combustion and lean combustion. This is generally characterized by λ, which stands for engine equivalence ratio. Specifically, λ is the ratio between the air-fuel ratio (the mass ratio of fuel to air) and the stoichiometric air-fuel ratio (the mass ratio of fuel to air required for complete combustion) during engine operation. The equivalence ratio is calculated by dividing the air-fuel ratio by the stoichiometric air-fuel ratio. The engine equivalence ratio is a crucial parameter that directly impacts combustion efficiency and exhaust emissions. It is usually controlled based on signals from the oxygen sensor at the engine exhaust.

[0041] When λ < 1, the engine is in a rich combustion state. At this time, due to the low oxygen content in engine 5, the conversion rate of hydrocarbons (HC) and carbon monoxide (CO) is low when exhaust gas is treated in the first treatment unit 1. Therefore, the content of HC and CO in the exhaust gas output from the first treatment unit 1 is high. Thus, the first treatment unit 1 is connected to the second treatment unit 2, and the HC and CO in the exhaust gas output from the first treatment unit 1 are treated by the second treatment unit 2, thereby reducing the pollutants in the exhaust gas under rich combustion state.

[0042] When λ > 1, the engine is in a lean-burn state, resulting in better fuel economy. At this time, the oxygen content is relatively abundant, leading to more complete combustion. However, due to the abundant oxygen content, during exhaust gas treatment in the first treatment unit 1, NH3 in the exhaust gas undergoes peroxidation, subsequently regenerating NO. X Therefore, the first processing unit 1 is connected to the third processing unit 3, and the third processing unit 3 processes the NO in the exhaust gas output by the first processing unit 1. X By processing these materials, pollutants in the exhaust gas under lean-burn conditions can be reduced, thus achieving ultra-low emission control of exhaust gases.

[0043] In specific applications, the second treatment unit 2 catalyzes the oxidation reaction of HC and CO in the exhaust gas output from the first treatment unit 1, thereby reducing the emissions of HC and CO. The reaction formula in the second treatment unit 2 is as follows:

[0044] 4HC + 5O₂ → 4CO₂ + 2H₂O (Equation 1)

[0045] 2CO + O2 → 2CO2 (Equation 2)

[0046] In the third processing unit 3, NO will be processed. X Catalysis is performed to reduce NO X The emissions, and the reaction formula in the third treatment unit 3 are as follows:

[0047] 4NH3 + 4NO + O2 → 4N2 + 6H2O (Equation 3)

[0048] 4NH3 + NO + NO2 → 2N2 + 3H2O (Equation 4)

[0049] 8NH3 + 6NO2 → 7N2 + 12H2O (Equation 5)

[0050] Understandably, by treating the exhaust gases under five different engine operating conditions separately, the content of gaseous pollutants in the final exhaust gas can be reduced, achieving ultra-low emission control; at the same time, it solves the problem of NO in the exhaust gas under lean-burn conditions. X After being regenerated in the first processing unit 1, it undergoes a second processing in the third processing unit 3, thereby extending the lean-burn operating time of the engine 5 and improving the fuel economy of the engine 5.

[0051] like Figure 1 As shown, in some embodiments of this application, a control unit 4 is also included. The control unit 4 is located at the output end of the first processing unit 1. The control unit 4 is used to control the output end of the first processing unit 1 to connect with the second processing unit 2, or to control the output end of the first processing unit 1 to connect with the third processing unit 3, based on the working state of the engine 5.

[0052] In this embodiment of the application, by setting a control unit 4 at the output end of the first processing unit 1, the first processing unit 1 and the second processing unit 2 or the third processing unit 3 in the exhaust gas treatment system can be connected according to the real-time working state of the engine 5, thereby enabling real-time exhaust gas treatment for different working states of the engine 5, improving the efficiency of exhaust gas treatment, reducing the emission of gaseous pollutants in the exhaust gas, and realizing ultra-low emission control of exhaust gas.

[0053] like Figure 1As shown, in some embodiments of this application, the control unit 4 includes a controller (not shown) and a switch 41; the controller is electrically connected to the engine 5, and the switch 41 is connected to the controller. The controller is used to control the opening and closing of the switch 41 based on the operating state of the engine 5.

[0054] In this embodiment of the application, the controller can control the opening and closing of the switch 41 according to the specific working state of the engine 5, so as to realize the connection between the first processing unit 1 and the second processing unit 2, or the connection between the first processing unit 1 and the third processing unit 3.

[0055] In specific applications, the controller can be an engine ECU or an engine management system (EMS). Those skilled in the art can configure it according to actual needs, and this application does not impose any restrictions on this. Specifically, the controller is used to realize the opening and closing of the switch 41 based on the operating state of the engine 5.

[0056] It should be explained that the controller can also be an independent unit, which can be electrically connected to the control module on the engine 5, and control the opening and closing of the switch 41 by acquiring the signal of the working status of the engine 5 sent by the control module on the engine 5.

[0057] Understandably, the switch 41 may be at least one of a three-way valve, multiple one-way valves, multiple check valves, etc. Those skilled in the art can configure it according to actual needs, and this application does not limit it.

[0058] like Figure 1 As shown, in some embodiments of this application, the switching element 41 includes a first control valve 411 and a second control valve 412. The first control valve 411 is located between the output end of the first processing unit 1 and the second processing unit 2, and is used to control the on / off state between the first processing unit 1 and the second processing unit 2. The second control valve 412 is located between the output end of the first processing unit 1 and the third processing unit 3, and is used to control the on / off state between the first processing unit 1 and the third processing unit 3.

[0059] In this embodiment, the controller can control the first control valve 411 to open when the engine 5 is in a rich combustion state, thereby connecting the first processing unit 1 and the second processing unit 2. At this time, the second control valve 412 is disconnected, and the first processing unit 1 and the third processing unit 3 are disconnected. When the engine is in a lean combustion state, the controller controls the second control valve 412 to open, thereby connecting the first processing unit 1 and the third processing unit 3. At this time, the first control valve 411 is disconnected, and the first processing unit 1 and the second processing unit 2 are disconnected. Thus, corresponding exhaust gas treatment is achieved for different operating states of the engine 5, reducing gaseous pollutants in the exhaust gas to meet emission standards and achieve ultra-low emission control of exhaust gas.

[0060] like Figure 1 As shown, in some embodiments of this application, the first processing unit 1 includes a TWC catalyst 11 (Three-way catalytic converter) and a first SCR catalyst 12 (Selective Catalytic Reduction). The TWC catalyst 11 is adapted to be connected to the exhaust outlet of the engine 5, and the first SCR catalyst 12 is connected to the output end of the TWC catalyst 11. The first SCR catalyst 12 is used to store ammonia gas generated by the TWC catalyst 11 and to process nitrogen oxides in the exhaust gas of the engine 5.

[0061] In this embodiment, the TWC catalytic converter 11 in the first processing unit 1 is connected to the exhaust outlet of the engine 5, and the first SCR catalytic converter 12 is connected to the output end of the TWC catalytic converter 11. Therefore, when the engine 5 is in a rich combustion state, the TWC catalytic converter 11 treats the exhaust gas from the engine 5 to remove NO. X The nitrogen is converted into NH3, and the generated NH3 is stored in the first SCR catalyst 12 for use in lean-burn conditions. The exhaust gas treated by the TWC catalyst 11 flows into the first SCR catalyst 12, where it continues to treat the exhaust gas, thereby reducing NO. X The content of urea is reduced, so there is no need to provide additional urea to the first SCR catalyst 12, thereby reducing system costs and saving vehicle space for the placement of other components.

[0062] It should be explained that when engine 5 is in a rich combustion state, the TWC catalytic converter 11 mainly removes NO from the exhaust gas of engine 5. X It is converted into NH3, and the generated NH3 is then stored in the first SCR catalyst 12 for use by the first SCR catalyst 12 when the engine 5 is in a lean-burn state.

[0063] In specific applications, under rich combustion conditions, the TWC catalyst 11 mainly produces NH3. The reaction formula in the TWC catalyst 11 is as follows:

[0064] 2NO + 5H2 → 2NH3+2H2O (Formula 6)

[0065] 2NO + 2CO+3H2 → 2NH3+2CO2 (Formula 7)

[0066] It needs to be explained that when engine 5 is in a lean-burn state, the TWC catalytic converter 11 converts HC and CO in the exhaust gas from engine 5, as shown in Equations 1 and 2. Simultaneously, NO, which cannot be processed by the TWC catalytic converter 11... X The NO flows into the first SCR catalyst 12, at which point NO is present in the first SCR catalyst 12. X The ammonia gas stored in the previous rich combustion state undergoes an NH3-SCR reaction, as shown in Equations 3, 4, and 5. This forms a passive catalytic reduction three-way catalytic converter (TWC+PSCR), thereby eliminating the need for the urea tank in traditional SCR catalytic technology, reducing system costs, and saving vehicle space.

[0067] In some embodiments of this application, the TWC catalyst 11 is provided with a first catalyst, which includes at least palladium.

[0068] In this embodiment, by setting the first catalyst in the TWC catalyst 11 to include at least palladium (Pd), NO can be effectively converted into nitrogen under enriched combustion conditions. X It converts NH3 to NH3 and, under lean-burn conditions, converts HC and CO to CO2 and H2O. Compared to the TWC catalyst in related technologies, it can provide ammonia for the NH3-SCR reaction and eliminate the need for urea aqueous solution.

[0069] It should be explained that in related technologies, the first catalyst in the TWC catalyst 11 usually contains three precious metals: platinum (Pt), rhodium (Rh), and palladium (Pd), and is therefore also called a three-way catalyst. Among them, palladium is the cheapest. Therefore, this application reduces the content of platinum and rhodium while satisfying the catalytic function of the TWC catalyst 11 itself, which can reduce the cost of the TWC catalyst 11 and thus reduce the cost of the exhaust gas treatment system.

[0070] In specific applications, the first catalyst in the TWC catalyst 11 is mainly palladium. For example, the palladium content can account for 80% of the total first catalyst, or it can be other proportions, so as to effectively generate ammonia while reducing the cost of the TWC catalyst 11.

[0071] In some embodiments of this application, the first processing unit 1 further includes a first ASC catalyst 13, which is connected to the output end of the first SCR catalyst 12. The first ASC catalyst 13 is used to process the ammonia gas discharged from the first SCR catalyst 12.

[0072] In this embodiment of the application, by connecting the output end of the first SCR catalyst 12 to the first ASC catalyst 13, the NH3 discharged with the exhaust gas can be further converted into N2, thereby ultimately reducing the NH3 content in the exhaust gas to meet emission standards and reduce environmental pollution.

[0073] It should be explained that during the exhaust gas treatment process, not all of the NH3 entering the first SCR catalyst 12 is converted. Instead, depending on the operating state of the engine 5 and the change in the NH3 content in the exhaust gas, a portion of the NH3 eventually enters the first ASC catalyst 13 along with the exhaust gas. The first ASC catalyst 13 can catalyze the NH3 entering it to convert it into N2, thereby reducing the NH3 content in the final exhaust gas, meeting emission standards, and achieving ultra-low emission control of exhaust gas.

[0074] like Figure 2 As shown, in some embodiments of this application, the first ASC catalyst 13 includes a second support 131, a noble metal coating 132 and an SCR catalyst coating 133, which are connected in sequence. The noble metal coating 132 includes at least platinum (Pt).

[0075] In this embodiment, the noble metal coating 132 in the first ASC catalyst 13 includes at least platinum. This coating can catalyze the oxidation reaction of NH3. After NH3 reacts with O2, it not only generates harmless N2, but also undergoes peroxidation to regenerate pollutants NO, NO2, and even N2O. The types of products are related to the O2 concentration. Therefore, an SCR catalyst coating 133 also needs to be coated on the noble metal coating 132. Its function and principle are the same as those of the first SCR catalyst 12, which is to react the NO generated in the noble metal coating 132 with the O2. X It is converted back to N2. The two catalytic coatings in the first ASC catalyst 13 work synergistically to achieve high NH3 conversion and high N2 selectivity, thereby reducing NH3 emissions while avoiding NO emissions. X The generation of .

[0076] In a specific application, NH3 is catalytically oxidized in the noble metal coating 132, and the specific reaction formula is as follows:

[0077] 4NH3 + 3O2 → 2N2 + 6H2O (Equation 8)

[0078] 4NH3 + 4O2 → 2N2O + 6H2O (Equation 9)

[0079] 4NH3 + 5O2 → 4NO + 6H2O (Equation 10)

[0080] 2NH3 + 7O2 → 4NO2 + 6H2O (Equation 11)

[0081] As can be seen from Equations 8-11 above, the reaction of NH3 with O2 not only produces harmless N2, but also undergoes peroxidation to regenerate pollutants NO, NO2, and even N2O, with the types of products related to the O2 concentration. When engine 5 switches between rich and lean combustion states, the oxygen content in the exhaust gas increases, causing NO to regenerate in the exhaust gas after treatment by the first treatment unit 1. X Therefore, when engine 5 is in a lean-burn state, control unit 4 connects the first processing unit 1 and the third processing unit 3, and the third processing unit 3 processes the NO in the exhaust gas output by the first processing unit 1. X The process involves reducing the amount of gaseous pollutants in the exhaust gas emitted by engine 5 under lean-burn conditions, thereby meeting emission standards and achieving ultra-low emission control.

[0082] like Figure 1 As shown, in some embodiments of this application, the first SCR catalyst 12 and the first ASC catalyst 13 are integrally formed.

[0083] In this embodiment of the application, by making the first SCR catalyst 12 and the first ASC catalyst 13 into an integral molded part, the processing efficiency can be improved and the cost of the exhaust gas treatment system can be reduced.

[0084] In practical applications, the first SCR catalyst 12 and the first ASC catalyst 13 are generally processed on the same carrier but at different locations to form the integral molded part.

[0085] like Figure 1 As shown, in some embodiments of this application, the second processing unit 2 includes a GOC catalyst 21 (Gasoline Oxidation Catalyst), which is connected to the output of the first processing unit 1 and is used to process hydrocarbons and carbon monoxide in the exhaust gas output by the first processing unit 1.

[0086] In this embodiment, when the engine 5 is in a rich combustion state, the control unit 4 connects the first processing unit 1 and the second processing unit 2. In the first processing unit 1, the TWC catalyst 11 removes NO from the exhaust gas emitted by the engine 5. X The HC and CO are converted into NH3 and stored in the first SCR catalyst 12. However, since the engine 5 is in a rich combustion state, the content of HC and CO is high. Therefore, the HC and CO in the exhaust gas output from the first treatment unit 1 enter the GOC catalyst 21 in the second treatment unit 2. The GOC catalyst 21 can oxidize HC and CO to generate H2O and CO2. The specific reaction formulas are shown in Equations 1 and 2. This can reduce the NO in the final exhaust gas when the engine 5 is in a rich combustion state. X The content of HC and CO is controlled to meet emission standards and further achieve ultra-low emission control of exhaust gas.

[0087] In some embodiments of this application, the GOC catalyst 21 includes a first support and a second catalyst coating, the second catalyst coating being attached to the first support, and the second catalyst coating including at least one of platinum and palladium.

[0088] In this embodiment, the GOC catalyst 21 includes a first support and a second catalyst coating, the second catalyst coating being attached to the first support, and the second catalyst coating comprising at least one of platinum and palladium. This allows for the catalytic oxidation of HC and CO by the GOC catalyst 21 while simultaneously controlling its cost.

[0089] It should be explained that in practical applications, the first carrier is a honeycomb ceramic carrier, and the second catalyst coating is coated on the pore surface of the ceramic carrier, so that when the exhaust gas flows into the pores, the second catalyst coating performs catalytic oxidation.

[0090] In specific applications, the exhaust gas discharged from the first ASC catalyst 13 passes through the gas passage in the first carrier. The untreated HC and CO in the exhaust gas are catalytically oxidized by the second catalyst coating to generate water and carbon dioxide, thereby reducing the content of gaseous pollutants in the exhaust gas under rich combustion conditions and achieving ultra-low emission control of exhaust gas.

[0091] In some embodiments of this application, the second catalyst coating further includes an oxygen storage material for storing oxygen.

[0092] In this embodiment, by adding an oxygen storage material to the second catalyst coating, oxygen can be stored to extend the residence time of oxygen in the GOC catalyst 21, thereby meeting the oxygen demand when HC and CO undergo oxidation reactions.

[0093] In specific applications, oxygen storage materials can be binary or multi-component composite oxides composed mainly of cerium oxide and rare earth elements, alkaline earth metal elements, or transition metal elements. Alternatively, other materials capable of oxygen storage can be used. Those skilled in the art can choose according to actual needs, and this application does not impose any restrictions.

[0094] like Figure 1 As shown, in some embodiments of this application, the second processing unit 2 further includes a gas replenishment device 22, which is located between the GOC catalyst 21 and the output end of the first processing unit 1. The gas replenishment device 22 is connected to the GOC catalyst 21 and is used to replenish oxygen to the GOC catalyst 21.

[0095] In this embodiment, by providing an air supply device 22, additional air can be supplied to the GOC catalyst 21 from the outside, thereby supplementing the GOC catalyst 21 with oxygen and meeting the oxygen demand when HC and CO undergo oxidation reactions.

[0096] In specific applications, the air replenishment device 22 can be an air pump or other device capable of replenishing air. Those skilled in the art can configure it according to actual needs, and this application does not impose any restrictions on it.

[0097] In some embodiments of this application, the supplemental air device 22 is electrically connected to the control unit 4, which can control the supplemental air device 22 to open when the engine 5 is in a rich combustion state, thereby supplementing oxygen to the GOC catalyst 21 to further reduce HC and CO emissions.

[0098] like Figure 1 As shown, in some embodiments of this application, the third processing unit 3 includes a second SCR catalyst 31, which is connected to the output end of the first processing unit 1. The second SCR catalyst 31 is used to treat nitrogen oxides in the exhaust gas output by the first processing unit 1.

[0099] In this embodiment, when the engine 5 switches between rich and lean combustion states, the oxygen content in the exhaust gas increases, causing NO to be regenerated in the exhaust gas after treatment by the first treatment unit 1. X Therefore, when engine 5 is in a lean-burn state, control unit 4 connects the first processing unit 1 and the third processing unit 3, and the second SCR catalyst 31 in the third processing unit 3 processes the NO in the exhaust gas output by the first processing unit 1. X The process involves reducing the amount of gaseous pollutants in the exhaust gas emitted by engine 5 under lean-burn conditions, thereby meeting emission standards and achieving ultra-low emission control.

[0100] In specific applications, the reaction formulas of the second SCR catalyst 31 and the first SCR catalyst 12 under lean combustion conditions are the same, as shown in Equations 3, 4 and 5, which will not be elaborated here.

[0101] Understandably, due to the NO in the exhaust gas treated by the first SCR catalyst 12 X The content of the catalyst is much higher than that of the second SCR catalyst 31. Therefore, the size of the second SCR catalyst 31 is much smaller than that of the first SCR catalyst 12. In actual use, the catalyst content in the second SCR catalyst 31 can be less than that in the first SCR catalyst 12.

[0102] like Figure 1 As shown, in some embodiments of this application, the third processing unit 3 further includes a second ASC catalyst 32, which is connected to the output end of the second SCR catalyst 31. The second ASC catalyst 32 is used to process the ammonia gas discharged from the second SCR catalyst 31.

[0103] In this embodiment of the application, by connecting the output end of the second SCR catalyst 31 to the second ASC catalyst 32, the NH3 discharged with the exhaust gas is further converted into N2, thereby ultimately reducing the NH3 content in the exhaust gas to meet emission standards and reduce environmental pollution.

[0104] In specific applications, the principle of the second ASC catalyst 32 is the same as that of the first ASC catalyst 13, as described above, and will not be repeated here.

[0105] It needs to be explained that the specific structure of the second ASC catalyst 32 is as follows: Figure 2 As shown, it has the same structure as the first ASC catalyst 13.

[0106] In some embodiments of this application, the second SCR catalyst 31 and the second ASC catalyst 32 are integrally molded parts. This improves processing efficiency and reduces costs.

[0107] In some embodiments of this application, both the first SCR catalyst 12 and the second SCR catalyst 31 in the first processing unit 1 contain a third catalyst, and the total amount of the third catalyst in the first SCR catalyst 12 is greater than the total amount of the third catalyst in the second SCR catalyst 31.

[0108] In this embodiment of the application, by making the total amount of the third catalyst in the first SCR catalyst 12 greater than the total amount of the third catalyst in the second SCR catalyst 31, the cost of the second SCR catalyst 31 can be reduced, thereby reducing the cost of the exhaust gas treatment system.

[0109] In specific applications, the third catalyst is used to catalyze NO. X Catalysts that react with NH3.

[0110] In practical applications, SCR catalysts and ASC catalysts are typically integrated components, installed in the exhaust pipe to treat the exhaust gases. Therefore, as... Figure 1 As shown, the arrow indicates the direction of exhaust gas flow. Along the exhaust gas flow direction, the sum of the lengths of the first SCR catalyst 12 and the first ASC catalyst 13 is greater than the sum of the lengths of the second SCR catalyst 31 and the second ASC catalyst 32.

[0111] Specifically, the combined length of the first SCR catalyst 12 and the first ASC catalyst 13 is between 4 and 6 feet, with the first ASC catalyst 13 accounting for 1 / 5 to 1 / 3 of the total length; while the combined length of the second SCR catalyst 31 and the second ASC catalyst 32 is between 1 and 2 feet.

[0112] In some embodiments of this application, a method for treating exhaust gas using the exhaust gas treatment system described in any of the above embodiments is also proposed. This method is used to treat the exhaust gas of an engine 5, wherein the engine operates in a rich combustion state and a lean combustion state. The method includes: when the engine 5 is in a rich combustion state, the control unit 4 controls the first processing unit 1 to connect with the second processing unit 2, so as to treat nitrogen oxides in the exhaust gas discharged by the engine 5 through the first processing unit 1, and to treat hydrocarbons and carbon monoxide in the exhaust gas through the second processing unit 2; when the engine 5 is in a lean combustion state, the control unit 4 controls the first processing unit 1 to connect with the third processing unit 3, so as to treat hydrocarbons, carbon monoxide and nitrogen oxides in the exhaust gas discharged by the engine 5 through the first processing unit 1, and to treat nitrogen oxides that were not completely treated by the first processing unit 1 through the third processing unit 3.

[0113] In this embodiment, when the engine 5 is in a rich combustion state, the exhaust gas discharged from the output end of the first processing unit 1 has a high content of hydrocarbons and carbon monoxide, and is then processed by the second processing unit 2; when the engine 5 is in a lean combustion state, the exhaust gas discharged from the output end of the first processing unit 1 has a high content of nitrogen oxides, and is then processed by the third processing unit 3; thus, the gaseous pollutants in the exhaust gas can be efficiently treated according to the specific operating state of the engine 5, thereby achieving ultra-low emission control of exhaust gas to meet increasingly stringent emission regulations.

[0114] In one embodiment of this application, the specific process of exhaust gas treatment using the above-described exhaust gas treatment system is as follows:

[0115] The controller controls the engine 5 to be in a rich or lean combustion state according to the vehicle's driving needs.

[0116] When engine 5 is in a rich combustion state:

[0117] The controller opens the first control valve 411 and closes the second control valve 412, allowing the TWC catalytic converter 11 to remove NO from the exhaust gas from engine 5. X The NH3 is converted into NH3 (specific reaction formulas are shown in Equations 6 and 7), and then stored in the first SCR catalyst 12. The first ASC catalyst 13 can prevent the leakage of NH3 stored in the first SCR catalyst by converting the NH3 leaking from the first SCR catalyst 12 into N2. The exhaust gas discharged from the first ASC catalyst 13 enters the GOC catalyst 21. At the same time, the controller controls the air supply device 22 to open and supply air to the GOC catalyst 21 to provide additional oxygen. The GOC catalyst 21 can oxidize HC and CO to generate H2O and CO2, and its specific reaction formulas are shown in Equations 1 and 2. In this way, when the engine 5 is in a rich combustion state, the exhaust gas treatment system can remove NO from the exhaust gas through multi-stage treatment. X Reduce gaseous pollutants such as HC and CO to achieve ultra-low emission control of exhaust gas;

[0118] When engine 5 is in a lean-burn state and transitioning from a rich-burn state to a lean-burn state:

[0119] The controller opens the second control valve 412 and closes the first control valve 411. The TWC catalyst 11 converts HC and CO in the exhaust gas from the engine 5, as shown in Equations 1 and 2. The first SCR catalyst 12 reacts with the NH3 stored in the previous rich combustion stage to perform an NH3-SCR reaction, thereby removing NO from the exhaust gas output by the TWC catalyst 11. X Converted to N2, thereby reducing NO X The emissions are specifically reacted as shown in equations 3, 4, and 5; the first ASC catalyst 13 can further convert a small portion of NH3 emitted with the exhaust gas from the first SCR catalyst 12 into N2; at this time, because the engine 5 is in a lean-burn state, the oxygen content in the exhaust gas is relatively high, and NH3 will undergo peroxidation, regenerating NO. X The exhaust gas from the first ASC catalyst 13 enters the second SCR catalyst 31, where the second SCR catalyst 31 uses NH3 in the exhaust gas to remove NO. X Converted to N2, thereby reducing NO X The emissions are specifically reacted as shown in equations 3, 4, and 5; the exhaust gas from the second SCR catalyst 31 enters the second ASC catalyst 32, where the second ASC catalyst 32 further converts NH3 in the exhaust gas into N2; thus, when the engine 5 is in a lean-burn state, the exhaust gas treatment system can remove NO from the exhaust gas through multi-stage treatment. XThe reduction of gaseous pollutants such as HC and CO meets emission requirements and achieves ultra-low emission control of exhaust gas.

[0120] In some embodiments of this application, a vehicle is also proposed that includes an exhaust gas treatment system as described in any of the above embodiments.

[0121] In this embodiment, based on the operating state of the engine 5, the output of the first processing unit 1 is connected to the second processing unit 2, or the output of the first processing unit 1 is connected to the third processing unit 3; thereby enabling the first processing unit 1 and the second processing unit 2 to work together to process the exhaust gas discharged from the engine 5, or the first processing unit 1 and the third processing unit 3 to work together to process the exhaust gas discharged from the engine 5. Specifically, in one operating state of the engine 5, the exhaust gas discharged from the output of the first processing unit 1 has a high content of hydrocarbons and carbon monoxide, and is then processed by the second processing unit 2; in another operating state of the engine 5, the exhaust gas discharged from the output of the first processing unit 1 has a high content of nitrogen oxides, and is then processed by the third processing unit 3; thus, the gaseous pollutants in the exhaust gas can be efficiently treated according to the specific operating state of the engine 5, thereby achieving ultra-low emission control of exhaust gas to meet increasingly stringent emission regulations.

[0122] In specific applications, the vehicle can be at least one of gasoline-powered vehicles, diesel-powered vehicles, natural gas-powered vehicles, hybrid vehicles, etc.

[0123] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0124] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An off-gas treatment system, characterized by, include: A first processing unit (1) is adapted to be connected to the exhaust outlet of an engine (5); The second processing unit (2) is connected to the output end of the first processing unit (1) and is used to process hydrocarbons and carbon monoxide in the exhaust gas output by the first processing unit (1). The third processing unit (3) is connected to the output terminal of the first processing unit (1) and is used to process nitrogen oxides in the exhaust gas output by the first processing unit (1). The second processing unit (2) and the third processing unit (3) may be selectively connected to the output of the first processing unit (1) to adapt to different operating states of the engine (5).

2. The exhaust gas treatment system according to claim 1, characterized in that, It also includes a control unit (4), which is located at the output end of the first processing unit (1). The control unit (4) is used to control the output end of the first processing unit (1) to connect with the second processing unit (2) or to control the output end of the first processing unit (1) to connect with the third processing unit (3) based on the working state of the engine (5).

3. The exhaust gas treatment system according to claim 2, characterized in that, The control unit (4) includes a controller and a switch (41); the switch (41) is connected to the controller, and the controller is used to control the opening and closing of the switch (41) based on the working state of the engine (5).

4. The exhaust gas treatment system according to claim 3, characterized in that, The switching element (41) includes a first control valve (411) and a second control valve (412). The first control valve (411) is located between the output end of the first processing unit (1) and the second processing unit (2) and is used to control the on / off state between the first processing unit (1) and the second processing unit (2). The second control valve (412) is located between the output end of the first processing unit (1) and the third processing unit (3) and is used to control the on / off state between the first processing unit (1) and the third processing unit (3).

5. The exhaust gas treatment system according to claim 1, characterized in that, The first processing unit (1) includes a TWC catalyst (11) and a first SCR catalyst (12). The TWC catalyst (11) is adapted to be connected to the exhaust outlet of the engine (5), and the first SCR catalyst (12) is connected to the output end of the TWC catalyst (11). The first SCR catalyst (12) is used to store ammonia gas generated by the TWC catalyst (11) and to process nitrogen oxides in the exhaust gas of the engine (5).

6. The exhaust gas treatment system according to claim 5, characterized in that, The TWC catalyst (11) is provided with a first catalyst, which includes at least palladium.

7. The exhaust gas treatment system according to claim 5, characterized in that, The first processing unit (1) further includes a first ASC catalyst (13), which is connected to the output end of the first SCR catalyst (12). The first ASC catalyst (13) is used to process the ammonia gas discharged from the first SCR catalyst (12).

8. The exhaust gas treatment system according to any one of claims 1-7, characterized in that, The second processing unit (2) includes a GOC catalyst (21), which is connected to the output end of the first processing unit (1) and is used to process hydrocarbons and carbon monoxide in the exhaust gas output by the first processing unit (1).

9. The exhaust gas treatment system according to claim 8, characterized in that, The second processing unit (2) further includes a gas replenishment device (22), which is located between the GOC catalyst (21) and the output end of the first processing unit (1). The gas replenishment device (22) is connected to the GOC catalyst (21) and is used to replenish oxygen to the GOC catalyst (21).

10. The exhaust gas treatment system according to claim 8, characterized in that, The GOC catalyst (21) includes a first support and a second catalyst coating, the second catalyst coating being attached to the support and comprising at least one of platinum and palladium.

11. The exhaust gas treatment system according to claim 10, characterized in that, The second catalyst coating also includes an oxygen storage material for storing oxygen.

12. The exhaust gas treatment system according to any one of claims 1-7, characterized in that, The third processing unit (3) includes a second SCR catalyst (31), which is connected to the output end of the first processing unit (1). The second SCR catalyst (31) is used to process nitrogen oxides in the exhaust gas output by the first processing unit (1).

13. The exhaust gas treatment system according to claim 12, characterized in that, The third processing unit (3) further includes a second ASC catalyst (32), which is connected to the output end of the second SCR catalyst (31). The second ASC catalyst (32) is used to process the ammonia gas discharged from the second SCR catalyst (31).

14. The exhaust gas treatment system according to claim 12, characterized in that, Both the first SCR catalyst (12) and the second SCR catalyst (31) in the first processing unit (1) contain a third catalyst, and the total amount of the third catalyst in the first SCR catalyst (12) is greater than the total amount of the third catalyst in the second SCR catalyst (31).

15. A method for treating exhaust gas using the exhaust gas treatment system according to any one of claims 1-14, for treating engine exhaust gas, wherein the engine (5) operates in a rich combustion state and a lean combustion state, characterized in that, include: When the engine (5) is in the rich combustion state, the control unit (4) controls the first processing unit (1) to communicate with the second processing unit (2) so that the first processing unit (1) processes the nitrogen oxides in the exhaust gas discharged by the engine (5), and the second processing unit (2) processes the hydrocarbons and carbon monoxide in the exhaust gas. When the engine (5) is in the lean-burn state, the control unit (4) controls the first processing unit (1) to communicate with the third processing unit (4) so ​​that the first processing unit (1) processes the hydrocarbons, carbon monoxide and nitrogen oxides in the exhaust gas discharged by the engine (5), and the third processing unit (3) processes the nitrogen oxides that were not processed by the first processing unit (1).

16. A vehicle, characterized in that, include: The exhaust gas treatment system as described in any one of claims 1-14.

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