Control method, device, equipment and medium for reducing N2O emission in engine

Abstract

The invention relates to a control method, device, equipment and medium for reducing N2O emission in an engine, and relates to the field of engine emission control. The control method comprises the steps that the temperature of an after-treatment SCR inlet is controlled to be larger than or equal to 250 DEG C; the conversion efficiency of a front-section oxidation catalyst is adjusted, and the volume ratio of NO2 in NOx is controlled to be 30-50%; the ammonia nitrogen ratio is adjusted through closed-loop control, so that the molar ratio of NH3 to NOx is (0.8-1.2): 1; and the emission amount of NOx in original emission of the engine is controlled to be smaller than or equal to 12 g / kWh. According to the control method provided by the invention, the process parameters of the related parts in the working process of the engine are synchronously regulated and controlled, so that the engine can realize lower N2O emission in the working process, and the emission amount of N2O is less than or equal to 195 kg / kWh.

Description

Technical Field

[0001] The present invention relates to the field of engine emission control, and particularly to a control method, device, equipment, and medium for reducing N2O emissions in an engine. Background Art

[0002] Currently, against the backdrop of strict control of stationary pollution sources and significant reduction of total pollution, the problem of mobile source pollution represented by motor vehicle emissions has become increasingly prominent. Regarding engine pollutant emissions, the limit requirements for NO x and other pollutants have been increased, and a new limit for N2O pollutant has been added.

[0003] Although there are many methods for reducing N2O pollutants in the prior art, for example, CN114658558A discloses a method, device, and vehicle for reducing N2O in vehicle exhaust. The method includes: obtaining the outlet temperature and space velocity value of a catalytic oxidizer; determining whether a diesel particulate filter is in an active regeneration state; and adjusting combustion parameters to reduce the N2O emissions in vehicle exhaust when the outlet temperature is within a preset temperature range, the space velocity value is less than a preset space velocity threshold, and the diesel particulate filter is in an active regeneration state.

[0004] CN115487859A discloses an N2O catalyst and a vehicle exhaust treatment system. The N2O catalyst includes a substrate and a catalyst coating coated on the substrate. The catalyst coating includes an N2O adsorption layer and an N2O decomposition layer; the N2O adsorption layer includes an N2O adsorbent, and the N2O adsorbent includes a molecular sieve and a noble metal; the N2O decomposition layer includes an N2O catalytic decomposition agent, and the N2O catalytic decomposition agent includes at least one of iron oxide, cobalt oxide, aluminum oxide, barium oxide, magnesium oxide, silicon oxide, strontium oxide, tin oxide, and germanium oxide. The provided N2O catalyst can absorb N2O in the exhaust gas by the N2O adsorption layer at a temperature lower than a certain temperature and release it at a temperature higher than a certain temperature, and then the catalyst in the N2O decomposition layer can decompose N2O into non-pollutants under the high temperature condition provided by a heating device. By adopting the method of low-temperature adsorption combined with high-temperature decomposition, it has the advantage of high N2O conversion efficiency and can reduce N2O emissions during vehicle cold start and the entire operation process.

[0005] In summary, the existing measures for reducing N2O emissions mainly include regulating engine process parameters or introducing new catalysts. However, introducing new catalysts will significantly increase costs and is not conducive to popularization and use. Therefore, controlling engine process parameters is an economical and efficient method for regulating N2O emissions. However, the current regulation method still has the defect of relatively high N2O emissions, which is not conducive to achieving efficient N2O emission reduction. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a control method for reducing N2O emissions in an engine, so as to solve the defect that the current regulation method still has a relatively high N2O emission, which is not conducive to the efficient reduction of N2O emissions.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a control method for reducing N2O emissions in an engine, and the control method includes:

[0009] Controlling the post-treatment SCR inlet temperature ≥ 250 °C;

[0010] Adjusting the conversion efficiency of the front-stage oxidation catalyst to control the volume ratio of NO2 in NO to be 30-50%; x The volume ratio of NO2 in NO is 30-50%;

[0011] Closed-loop control to adjust the ammonia-nitrogen ratio so that the molar ratio of NH3 / NO is (0.8-1.2):1; x The molar ratio of NH3 / NO is (0.8-1.2):1;

[0012] Controlling the emission of NO in the original engine emissions ≤ 12 g / kWh. x The emission of NO is ≤ 12 g / kWh.

[0013] The control method provided by the present invention enables the engine to achieve lower N2O emissions during operation by synchronously regulating the process parameters of relevant parts during the engine operation process, and the N2O emission ≤ 195 kg / kWh.

[0014] As a preferred technical solution of the present invention, the method for controlling the post-treatment SCR inlet temperature includes: an EGR control strategy or a thermal management strategy.

[0015] As a preferred technical solution of the present invention, the thermal management strategy includes: electric heating and / or post-injection of fuel.

[0016] As a preferred technical solution of the present invention, the adjustment method for adjusting the conversion efficiency of the front-stage oxidation catalyst includes: adjusting the temperature of the pre-stage SCR and / or the space velocity of the pre-stage SCR.

[0017] As a preferred technical solution of the present invention, the closed-loop control for adjusting the ammonia-nitrogen ratio includes: efficiency closed-loop feedforward and efficiency closed-loop feedback.

[0018] As a preferred technical solution of the present invention, the efficiency closed-loop feedforward includes: obtaining the target efficiency of the post-stage SCR according to the expected downstream NO value and the upstream NO value; then obtaining the feedforward ammonia-nitrogen ratio according to the target efficiency of the post-stage SCR, the bed temperature of the post-stage SCR carrier and the space velocity of the post-stage SCR. x Value, upstream NO x Value to obtain the target efficiency of the post-stage SCR; then obtain the feedforward ammonia-nitrogen ratio according to the target efficiency of the post-stage SCR, the bed temperature of the post-stage SCR carrier and the space velocity of the post-stage SCR.

[0019] Preferably, the desired downstream NO x value is obtained based on the rotational speed and fuel injection quantity.

[0020] As a preferred technical solution of the present invention, the efficiency closed-loop feedback includes: taking the difference between the actual SCR efficiency and the target efficiency of the post-stage SCR, and obtaining the feedback control ammonia-nitrogen ratio NH3 / NO x .

[0021] In a second aspect, the present invention provides a control device for reducing N2O emissions in an engine. The control device includes:

[0022] A post-treatment SCR inlet temperature control module for controlling the post-treatment SCR inlet temperature ≥ 250°C;

[0023] A conversion efficiency control module for adjusting the conversion efficiency of the front-stage oxidation catalyst to control the volume ratio of NO2 in NO x to be 30-50%;

[0024] An ammonia-nitrogen ratio control module for closed-loop controlling and adjusting the ammonia-nitrogen ratio to make the molar ratio of NH3 / NO x be (0.8-1.2):1;

[0025] A raw emission control module for controlling the emission of NO in the raw emissions of the engine x to be ≤ 12 g / kWh.

[0026] In a third aspect, the present invention provides an electronic device. The electronic device includes:

[0027] At least one processor; and a memory communicatively connected to the at least one processor;

[0028] Wherein, the memory stores a computer program executable by the at least one processor. The computer program is executed by the at least one processor so that the at least one processor can execute the control method for reducing N2O emissions in the engine described in the first aspect.

[0029] In a fourth aspect, an embodiment of the present invention provides a computer storage medium. The computer storage medium stores computer-executable instructions. When the computer-executable instructions are executed by a processor, the control method for reducing N2O emissions in the engine described in the first aspect is implemented.

[0030] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0031] The control method provided by the present invention can effectively control N2O emissions by synchronously regulating the process parameters of relevant parts during the engine operation, enabling the engine to achieve lower N2O emissions during operation. The N2O emissions ≤ 195 kg / kWh, thus meeting the current national VII limit requirements without increasing costs. Description of the Drawings

[0032] Figure 1 is a flowchart of the control method for reducing N2O emissions in the engine provided by the embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of the control device for reducing N2O emissions in the engine provided by the embodiment of the present invention;

[0034] Figure 3 is a schematic diagram of the electronic device provided by the embodiment of the present invention;

[0035] Figure 4 is a temperature management result diagram of the post-treatment SCR inlet temperature in Embodiment 1 of the present invention;

[0036] Figure 5 is a schematic diagram of the dynamic urea injection strategy in Embodiment 1 of the present invention;

[0037] Figure 6 is a control flowchart for controlling the ammonia-nitrogen ratio by optimizing the original emissions and urea injection control strategy in Embodiment 1 of the present invention.

[0038] In the figure: 100 - post-treatment SCR inlet temperature control module, 200 - conversion efficiency control module, 300 - ammonia-nitrogen ratio control module, 400 - original emissions control module;

[0039] 10 - electronic device, 11 - processor, 12 - ROM, 13 - RAM, 14 - bus, 15 - I / O interface, 16 - input unit, 17 - output unit, 18 - storage unit, 19 - communication unit.

[0040] The present invention will be further described in detail below. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims. Detailed Embodiments

[0041] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0042] This embodiment provides a control method for reducing N2O emissions in an engine, and the process is as Figure 1 shown. The emission control method includes:

[0043] Control the post-processing SCR inlet temperature ≥ 250℃;

[0044] Adjust the conversion efficiency of the front oxidation catalyst to control NO x The volume percentage of NO2 is 30-50%;

[0045] Closed-loop control adjusts the ammonia nitrogen ratio to make NH3 / NO x The molar ratio is (0.8-1.2):1;

[0046] Control NO in the original engine emissions x The emission is ≤12g / kWh.

[0047] In the present invention, during the control process, the post-processing SCR inlet temperature is controlled to be ≥250°C. For example, the temperature can be controlled to be 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 320°C, 340°C, 360°C, 380°C or 400°C, but is not limited to the listed values. Other values not listed in this range also meet the requirements.

[0048] In the present invention, the control process controls NO x The volume proportion of NO2 is 30-50%, for example, it can be 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48% or 50%, but is not limited to the listed values, and other unlisted values within the range also meet the requirements.

[0049] In the present invention, the closed-loop control during the control process adjusts the ammonia nitrogen ratio so that NH3 / NO x The molar ratio is (0.8-1.2):1, for example, it can be 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1, but is not limited to the listed values, and other unlisted values within the range also meet the requirements.

[0050] In the present invention, the NO in the original emission of the engine is controlled during the control process. x The emission amount is ≤12g / kWh, for example, it can be 12g / kWh, 11.5g / kWh, 11g / kWh, 10.5g / kWh, 10g / kWh, 9.5g / kWh, 9g / kWh, 8.5g / kWh, 8g / kWh, 7.5g / kWh, 7g / kWh, 6.5g / kWh, 6g / kWh, 5.5g / kWh or 5g / kWh, but is not limited to the listed values. Other values not listed in the range also meet the requirements.

[0051] Wherein, the method of controlling the post-processing SCR inlet temperature includes: EGR control strategy or thermal management strategy.

[0052] In the present invention, the EGR control strategy is the exhaust gas recirculation process, specifically: the introduced exhaust gas dilutes the oxygen concentration in the intake air, which means that relatively more fuel burns in the cylinder, generating more heat, thereby increasing the exhaust gas temperature. On the other hand, the introduced exhaust gas slows down the combustion speed, prolonging the combustion process and increasing the afterburning phenomenon, that is, the combustion process continues during the expansion stroke, and more fuel burns during the downward movement of the piston, thus increasing the exhaust gas temperature.

[0053] Among them, the thermal management strategy includes: electric heating and / or post-injection of fuel.

[0054] In the present invention, the electric heating refers to adding an electric heating EHC arrangement between the engine and the after-treatment SCR system to achieve the control of the SCR inlet temperature; specifically, when the pre-stage SCR inlet temperature is lower than the threshold (≥250 °C), the electric heating is started, and the electric heating heats the exhaust gas through a resistance wire. After the pre-stage SCR inlet temperature is higher than the threshold (≥250 °C), the electric heating is turned off.

[0055] In the present invention, the post-injection of fuel refers to the far post-injection control strategy of the diesel generator fuel supply system, and the DOC is ignited to improve the management of the SCR system inlet temperature; specifically, when the pre-stage SCR inlet temperature is lower than the threshold (≥250 °C), the injector performs near post-injection. The near post-injected fuel burns insufficiently in the cylinder, increasing the exhaust gas temperature by a large amount of heat. After the pre-stage SCR inlet temperature is higher than the threshold (≥250 °C), the near post-injection function is stopped.

[0056] Among them, the adjustment method for adjusting the conversion efficiency of the front-stage oxidation catalyst includes: adjusting the pre-stage SCR temperature and / or the pre-stage SCR space velocity. Specifically, the adjustment process principle is as follows: adjust the pre-stage SCR temperature and space velocity conditions, set the pre-stage SCR target efficiency Eff_Dmd, and adjust the SCR inlet NO x concentration and the SCR outlet NO x concentration to obtain the pre-stage SCR actual efficiency Eff_Act. According to the pre-stage SCR target efficiency Eff_Dmd and the pre-stage SCR actual efficiency Eff_Act, obtain the efficiency difference e_Eff. Through the PID controller, obtain the pre-stage SCR urea injection ammonia-nitrogen ratio U_f, specifically as follows:

[0057]

[0058] In the formula, Kp_f is the control parameter of the proportional controller; Ki_f is the control parameter of the integral controller; Kd_f is the control parameter of the differential controller; t is the controller operation time; U_f is the pre-stage SCR urea injection ammonia-nitrogen ratio.

[0059] Among them, according to the NO at the inlet of the pre-stage SCR x sensor measurement value NO x1 , the NO at the outlet of the pre-stage SCR x sensor measurement value NO x2 , calculate the conversion efficiency of the pre-stage SCR Eff = |NO x1 -NO x2 | / NO x1 .

[0060] Among them, the closed-loop control to adjust the ammonia-nitrogen ratio includes: efficiency closed-loop feedforward and efficiency closed-loop feedback.

[0061] Among them, the efficiency closed-loop feedforward includes: according to the expected downstream NO x value, the NO at the inlet of the post-stage SCR x sensor measurement value, that is, the upstream NO x value, calculate the target efficiency of the post-stage SCR, and according to the target efficiency of the post-stage SCR, the carrier bed temperature of the post-stage SCR and the space velocity of the post-stage SCR, obtain the feedforward ammonia-nitrogen ratio of the post-stage SCR.

[0062] Among them, the expected downstream NO x value is obtained based on the rotational speed and fuel injection volume, specifically as follows:[[]]

[0063] Set the target NO x emission ratio power value x, unit g / Kwh, through universal data, obtain the engine power P under different rotational speeds and fuel injection volumes, unit kW, the expected downstream NO x mass flow rate NO x _Dmd = target NO x emission ratio power value x × engine power P, that is:[[]]

[0064] NO x _Dmd[g / h] = x[g / kWh] × P[kW].[[]]

[0065] Among them, the efficiency closed-loop feedback includes: by taking the difference between the actual efficiency of the SCR and the target efficiency of the post-stage SCR, and passing through a PID controller to obtain the feedback control ammonia-nitrogen ratio NH3 / NO x , specifically as follows:[[]]

[0066] By taking the difference between the actual efficiency of the SCR and the target efficiency of the post-stage SCR, obtain the efficiency deviation e. The PID controller consists of a proportional controller, an integral controller and a derivative controller. The PID controller obtains the feedback control ammonia-nitrogen ratio in the following way:[[]]

[0067]

[0068] In the formula, K p is the control parameter of the proportional controller; e is the efficiency deviation; Ki is the integral controller control parameter; K d is the derivative controller control parameter; t is the controller operation time; u is the feedback control ammonia-nitrogen ratio.

[0069] Furthermore, this embodiment provides a control device for reducing N2O emissions in an engine, as Figure 2 shown, the emission control device includes:

[0070] A post-treatment SCR inlet temperature control module 100, used to control the post-treatment SCR inlet temperature ≥ 250 °C;

[0071] A conversion efficiency control module 200, used to adjust the conversion efficiency of the front-stage oxidation catalyst and control the volume ratio of NO2 in NO to be 30-50%; x

[0072] An ammonia-nitrogen ratio control module 300, used for closed-loop control to adjust the ammonia-nitrogen ratio so that the molar ratio of NH3 / NO is (0.8-1.2):1; x

[0073] A raw emission control module 400, used to control the NO emissions in the engine raw emissions to be ≤ 12 g / kWh. x

[0074] Regarding the device in the above embodiment, the specific ways in which each module performs operations have been described in detail in the embodiment related to the method, and will not be elaborated here.

[0075] Furthermore, the present invention provides an electronic device. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are only examples and are not intended to limit the implementation of the present invention described herein and / or claimed.

[0076] As Figure 3 ​​​As shown, the electronic device 10 includes at least one processor 11 and a memory communicatively connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc. The memory stores a computer program executable by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other via a bus 14. The I / O interface 15 is also connected to the bus 14.

[0077] Multiple components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disc, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0078] The processor 11 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the processor 11 include but are not limited to a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the aforementioned control method for reducing N2O emissions in the engine.

[0079] In some embodiments, the aforementioned control method for reducing N2O emissions in the engine can be implemented as a computer program tangibly embodied in a computer-readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the aforementioned control method for reducing N2O emissions in the engine described above can be executed. Alternatively, in other embodiments, the processor 11 can be configured to execute the aforementioned control method for reducing N2O emissions in the engine by any other appropriate means (e.g., by means of firmware).

[0080] The various embodiments of the systems and techniques described above in this specification can be implemented in digital electronic circuitry, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems-on-chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: being implemented in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which may be a special-purpose or general-purpose programmable processor that receives data and instructions from, and transmits data and instructions to, a storage system, at least one input device, and at least one output device.

[0081] The computer programs for implementing the methods of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the computer programs, when executed by the processor, cause the functions / operations specified in the flowchart and / or block diagram to be implemented. The computer programs can be executed entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0082] In the context of the present invention, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, the computer-readable storage medium can be a machine-readable signal medium. More specific examples of the machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0083] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or a trackball) through which the user can provide input to the electronic device. Other kinds of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, speech input, or tactile input).

[0084] The systems and techniques described herein can be implemented in a computing system including backend components (e.g., as a data server), or a computing system including middleware components (e.g., an application server), or a computing system including frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system including any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected to each other by digital data communication in any form or medium (e.g., a communication network). Examples of communication networks include: local area network (LAN), wide area network (WAN), blockchain network, and the Internet.

[0085] A computing system can include a client and a server. The client and the server are generally remote from each other and typically interact through a communication network. The client-server relationship is created by computer programs running on respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or a cloud host, which is a host product in the cloud computing service system, solving the defects of the traditional physical host and VPS service, such as high management difficulty and weak business scalability.

[0086] The server provided in this embodiment includes: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the foregoing control method for reducing N2O emissions in the engine.

[0087] Unless otherwise specifically stated, terms such as processing, computing, calculating, determining, displaying, etc. can refer to the actions and / or processes of one or more processing or computing systems, or similar devices, which operate on and transform data represented as a physical (such as electronic) quantity within the registers or memories of the processing system into other data similarly represented as a physical quantity within the memories, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different technologies and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0088] Those skilled in the art should also understand that the various illustrative logical blocks, modules, circuits, and algorithmic steps described in connection with the embodiments of the present invention can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the above description of the various illustrative components, blocks, modules, circuits, and steps has been generally described in terms of their functions. Whether such a function is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Skilled artisans can implement the described functions in a flexible manner for each specific application, but such implementation decisions should not be construed as departing from the scope of the present invention.

[0089] The steps of the methods or algorithms described in connection with the embodiments herein can be directly embodied as hardware, software modules executed by a processor, or a combination thereof. The software modules can be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium well-known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from and write information to the storage medium. Of course, the storage medium can also be a part of the processor. The processor and the storage medium can be located in an ASIC. The ASIC can be located in a user terminal. Of course, the processor and the storage medium can also exist as discrete components in the user terminal.

[0090] For a software implementation, the techniques described in the present invention can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or outside the processor. In the latter case, it is communicatively coupled to the processor by various means, which are well-known in the art.

[0091] Further, to clarify what is provided by the present invention, actual examples are used for illustration as follows:

[0092] Example 1

[0093] This example provides a control method for reducing N2O emissions in an engine based on an actual engine, and the process is as follows:

[0094] Raise the temperature in the low-temperature section: Increase the temperature at the inlet of the post-stage SCR to above 250°C through an EGR strategy (exhaust gas recirculation) or a thermal management strategy (such as electric heating, post-injection of fuel) to inhibit low-temperature side reactions, and the results are as Figure 4 shown.

[0095] Optimize the urea injection control strategy to precisely control the ammonia-nitrogen ratio (NH3 / NO x ), as follows:

[0096] Dynamic urea injection strategy: Adjust the urea injection amount through closed-loop control to avoid excessive NH3 (causing side reactions) or insufficient NH3 (causing incomplete reactions), and the process is as Figure 5 shown.

[0097] Efficiency closed-loop feedforward: Obtain the expected downstream NO x value by looking up the rotational speed and fuel injection amount, combine it with the upstream NO x value to obtain the target efficiency of the post-stage SCR, and look up the feedforward ammonia-nitrogen ratio of the post-stage SCR according to the target efficiency of the post-stage SCR, the bed temperature of the post-stage SCR, and the space velocity of the post-stage SCR.

[0098] Efficiency closed-loop feedback: Subtract the actual efficiency of the SCR from the target efficiency of the post-stage SCR, and obtain the feedback control ammonia-nitrogen ratio (NH3 / NO x ) through a PID controller, and superimpose the feedforward and feedback ammonia-nitrogen ratios to output the final ammonia-nitrogen ratio.

[0099] Optimize the calibration to control the original engine emissions: Reduce the original engine emissions through the engine control strategy (such as changing the fuel injection advance angle), which can reduce the urea injection amount, thereby reducing the generation of NH3 and also reducing the generation of N2O.

[0100] Through the above regulations, the N2O emissions in the exhaust gas generated by this engine system can be ≤195 kg / kWh.

[0101] The N2O emission verification analysis of the dual-stage SCR scheme was carried out on a certain 13-liter engine. The measuring equipment measured multiple measuring points, namely measuring point 1 of the test, measuring point 2 of the test, and measuring point 3 of the test, simultaneously. The front and rear stages of SCR were emptied, and no urea injection was carried out in both the front and rear stages (cold + hot WHTC cycle); Test 4: Normal urea injection was carried out in the front and rear stages of SCR (cold + hot WHTC cycle); The test verified that N2O generation is an intermediate product in the SCR catalytic reaction path. At the same time, by optimizing the original exhaust and urea injection control strategies to accurately control the ammonia-nitrogen ratio, the result of Test 4, 153.2 mg / kWh, was achieved, meeting the requirement of being less than the target limit of 195 mg / kWh. The process is as Figure 6 shown.

[0102] It is stated that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0103] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0104] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any appropriate manner. To avoid unnecessary repetition, the present invention does not separately describe various possible combination methods.

[0105] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A control method for reducing N2O emissions in an engine, characterized in that, The control method includes: Controlling the post-treatment SCR inlet temperature ≥ 250°C; Adjust the conversion efficiency of the front-stage oxidation catalytic converter to control NO x The volume percentage of NO2 in it is 30-50%; Closed-loop control adjusts the ammonia-nitrogen ratio to make the molar ratio of NH3 / NO x be (0.8 - 1.2):1; Control the NO emissions in the original engine emissions x ≤ 12 g / kWh.

2. The control method according to claim 1, wherein The method for controlling the post-treatment SCR inlet temperature includes: an EGR control strategy or a thermal management strategy.

3. The control method according to claim 2, wherein The thermal management strategy includes: electric heating and / or post-injection of fuel.

4. The control method according to claim 1, wherein, The adjustment method for adjusting the conversion efficiency of the front-stage oxidation catalyst includes: adjusting the front-stage SCR temperature and / or the front-stage SCR space velocity.

5. The control method according to claim 1, wherein, The closed-loop control for adjusting the ammonia-nitrogen ratio includes: efficiency closed-loop feedforward and efficiency closed-loop feedback.

6. The control method according to claim 5, wherein The efficiency closed-loop feedforward includes: obtaining the target efficiency of the downstream SCR according to the expected downstream NO x value and the upstream NO x value; then obtaining the feedforward ammonia-nitrogen ratio according to the target efficiency of the downstream SCR, the bed temperature of the downstream SCR carrier, and the space velocity of the downstream SCR; Preferably, the desired downstream NO x value is obtained based on the rotational speed and the fuel injection amount.

7. The control method according to claim 5, characterized in that, The efficiency closed-loop feedback includes: calculating the difference between the actual efficiency of the SCR and the target efficiency of the subsequent SCR, and obtaining the feedback control ammonia-nitrogen ratio NH3 / NO through a PID controller x .

8. A control device for reducing N2O emissions in an engine, characterized in that, The control device includes: A post-treatment SCR inlet temperature control module for controlling the post-treatment SCR inlet temperature ≥ 250°C; The conversion efficiency control module is used to adjust the conversion efficiency of the front-stage oxidation catalytic converter and control NO x The volume percentage of NO2 in it is 30-50%; Ammonia-nitrogen ratio control module, which is used for closed-loop control to adjust the ammonia-nitrogen ratio so that the molar ratio of NH3 / NO x is (0.8 - 1.2):1; The original emission control module is used to control the NO emissions in the original emissions of the engine x ≤ 12 g / kWh.

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and a memory communicatively connected to the at least one processor; Wherein, the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the control method for reducing N2O emissions in the engine according to any one of claims 1-7.

10. A computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, the control method for reducing N2O emissions in the engine according to any one of claims 1-7 is implemented.

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