Urea injection control method and related equipment

Abstract

The invention discloses a urea injection control method and related equipment, and relates to the technical field of double-injection SCR systems, and the urea injection control method comprises the steps that the temperature of ufSCR of a double-injection SCR system is obtained; according to the temperature and the heating rate of the ufSCR, whether NH3 leakage exists or not is judged; and when NH3 leakage exists, the urea injection amount of ccSCR and ufSCR of the double-injection SCR system is controlled to be reduced to a set value, and after the NH3 storage amount is smaller than the set storage minimum value, the urea injection amount of ccSCR and ufSCR is recovered. The NH3 emission is effectively reduced under the condition of effectively ensuring the low emission of NOx, meanwhile, the emission of N2O side reaction generated in the SCR / ASC system due to excessive NH3 is reduced, and the effective reduction of all pollutants is realized.

Description

Technical Field

[0001] This invention relates to the field of dual-injection SCR system technology, and in particular to a urea injection control method and related equipment. Background Technology

[0002] The main way to reduce NOx in diesel engines is through the reaction of NH3 produced by urea hydrolysis with NOx in an SCR (Selective Catalytic Reduction) system to generate pollution-free N2.

[0003] However, if the SCR temperature is too high, the NOx conversion efficiency will decrease, which will cause the NH3 stored in the SCR system to be released, and some excess NH3 will be discharged through the ASC (ammonia slip catalyst), generating N2O in the ASC, resulting in excessive NH3 and N2O emissions. Furthermore, this part of the NH3 is generated by the hydrolysis of urea, and the waste of excess NH3 will also lead to excessive consumption of urea injection, increasing the operating cost. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a urea injection control method and related equipment, which effectively reduces NH3 emissions while ensuring low NOx emissions, and simultaneously reduces N2O side reactions caused by excessive NH3 in the SCR / ASC system, thereby achieving effective reduction of all pollutants.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a urea injection control method applied to a dual-injection SCR system, comprising: Obtain the temperature of the ufSCR in the dual-jet SCR system; Determine whether there is an NH3 leak based on the temperature and heating rate of the ufSCR. When NH3 leakage occurs, the urea injection rate of the ccSCR and ufSCR in the dual-injection SCR system is reduced to the set value until the NH3 storage level is less than the set minimum storage level, at which point the urea injection rate of the ccSCR and ufSCR is restored.

[0006] As an alternative implementation, when the temperature of the ufSCR is greater than a set temperature threshold and the heating rate of the ufSCR is greater than a set temperature change threshold, it is determined that there is an NH3 leak.

[0007] As an alternative implementation, the urea injection rate of the ccSCR is controlled to maintain a minimum injection rate.

[0008] As an alternative implementation, the urea injection rate of the ufSCR is reduced to the minimum injection rate.

[0009] As an alternative implementation, the minimum storage value is the minimum amount of NH3 stored to ensure NOx conversion efficiency for ufSCR.

[0010] As an alternative implementation method, a small amount of over-spraying is performed after the urea injection volume of the ccSCR is restored to normal.

[0011] Secondly, the present invention provides a urea injection control system applied to a dual-injection SCR system, comprising: The acquisition module is configured to acquire the temperature of the ufSCR in the dual-injection SCR system; The judgment module is configured to determine whether there is an NH3 leak based on the temperature and heating rate of the ufSCR. The control module is configured to reduce the urea injection rate of the ccSCR and ufSCR of the dual-injection SCR system to a set value when there is an NH3 leak, and then restore the urea injection rate of the ccSCR and ufSCR after the NH3 storage amount is less than the set minimum storage value.

[0012] Thirdly, the present invention provides an electronic device including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0013] Fourthly, the present invention provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in the first aspect.

[0014] Fifthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the method described in the first aspect.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes a urea injection control method. By judging the temperature and heating rate of the ufSCR (Under-Chip SCR), it is determined whether there is an NH3 leakage problem in the ufSCR. If so, the urea injection rate of both the cSCR (Chip-Chip SCR) and the ufSCR is reduced. This reduces the NH3 storage in the ufSCR by increasing NOx emissions before the ufSCR and decreasing the urea injection rate of the ufSCR, thereby reducing the risk of NH3 leakage. Once there is no NH3 leakage risk in the ufSCR, the urea injection rates of both the cSCR and the ufSCR are restored, and the urea injection rate of the cSCR is appropriately increased to reduce NOx emissions before the ufSCR, thus reducing total NOx emissions. This effectively reduces NH3 emissions while maintaining low NOx emissions, and also reduces the emissions of N2O side reactions caused by excessive NH3 in the SCR / ASC system, achieving an effective reduction of all pollutants.

[0016] Advantages of additional aspects of the invention 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 the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the post-processing system provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the NOx conversion efficiency and temperature of the SCR system provided in Embodiment 1 of the present invention; Figure 3 This is a flowchart of the urea injection control method provided in Embodiment 1 of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0023] Example 1 To meet the upgrade requirements for next-generation emissions from internal combustion engines, diesel engine systems often employ dual-injection SCR systems, as shown in the diagram below. Figure 1 As shown, it includes a ccSCR / ccASC+DOC (diesel oxidation catalyst) + DPF (diesel particulate filter) + ufSCR / ufASC system, and contains two urea injection systems, four temperature sensors, and an electronic control unit that is electrically connected to the urea injection system and temperature sensors to collect engine operating status and temperature signals and control the urea injection system to inject urea.

[0024] To improve the NOx conversion efficiency of dual-injection SCR systems, a small amount of urea is often over-injected, causing some NH3 to be stored in the SCR. However, as the temperature of the SCR system increases, the amount of NH3 stored decreases. If the temperature suddenly rises to an excessively high level, the NH3 stored in the SCR will be released, leading to excessive NH3 emissions. Furthermore, the NOx conversion efficiency of the SCR also decreases at high temperatures. Figure 2 As shown.

[0025] Current control technologies, which do not have requirements for NH3, often reduce NOx by excessive urea injection. However, this leads to a further increase in NH3 emissions, failing to meet the requirements of next-generation emissions standards. Furthermore, excessive NH3 emissions result in the formation of N2O byproducts in SCR / ASC, also causing N2O emissions to exceed limits.

[0026] Therefore, this embodiment proposes a urea injection control method, which mainly solves the problem of excessive NH3 and N2O emissions caused by excessive NH3 leakage in the SCR system, especially the ufSCR, when the temperature suddenly increases to an excessively high temperature.

[0027] like Figure 3 As shown, it specifically includes: (1) Obtain the upstream temperature of the ufSCR in the dual-jet SCR system.

[0028] (2) Determine whether the upstream temperature of the ufSCR is greater than the set temperature threshold.

[0029] The setting of this threshold is related to the SCR system catalyst and needs to be determined based on the characteristics of the SCR system catalyst and experiments; for example... Figure 2 As shown, the temperature threshold can be set to 350℃.

[0030] (3) If the upstream temperature of ufSCR is greater than the temperature threshold, then continue to determine whether the heating rate ΔT of ufSCR is greater than the set temperature change threshold, so as to determine whether the temperature rise rate of ufSCR is too fast.

[0031] The heating rate ΔT is calculated from the temperature T1 corresponding to time t1 and the temperature T2 corresponding to time t2, ΔT=(T2-T1) / (t2-t1); t2>t1.

[0032] The setting of the temperature change threshold is related to the catalysis of the SCR system and needs to be determined based on the characteristics of the SCR system catalyst and experiments.

[0033] (4) If the heating rate ΔT of the ufSCR is greater than the set temperature change threshold, it means that the temperature rises too fast, which will lead to excessive NH3 leakage in the SCR system. Therefore, reducing the urea injection rate of the cCSCR, keeping the urea injection rate of the cCSCR at the minimum injection rate required by the hardware, is used to reduce the NOx conversion of the cCSCR system, so that more NOx enters the ufSCR to consume the NH3 stored therein. At the same time, the urea injection rate of the ufSCR was reduced to the minimum injection rate, which was determined by experiment, in order to further reduce the NH3 stored in the ufSCR.

[0034] (5) Determine whether the amount of NH3 stored in ufSCR is less than the set minimum storage value.

[0035] The minimum storage value is the minimum NH3 storage amount required for the ufSCR to guarantee NOx conversion efficiency, while ensuring no NH3 leakage at this high temperature.

[0036] (6) If the NH3 storage amount is less than the minimum NH3 storage amount, it indicates that the risk of NH3 leakage in the ufSCR system is extremely small. In order to ensure the minimum NOx emission, the urea injection amount of the ccSCR is controlled to return to normal, or even a small amount of over-injection is carried out. This over-injection amount is determined by experiment and is used to reduce NOx before entering the ufSCR. At the same time, the urea injection amount of the ufSCR is controlled to return to normal.

[0037] This embodiment of the method determines whether there is an NH3 leakage problem in the ufSCR by judging the temperature and heating rate of the ufSCR. If there is, the urea injection rate of both the cSCR and ufSCR is reduced. This reduces the NH3 storage in the ufSCR by increasing NOx emissions before the ufSCR and decreasing the urea injection rate of the ufSCR, thereby reducing the risk of NH3 leakage. Once there is no risk of NH3 leakage in the ufSCR, the urea injection rates of both the cSCR and ufSCR are restored, and the urea injection rate of the cSCR is appropriately increased to reduce NOx emissions before the ufSCR, thus reducing total NOx emissions. This effectively reduces NH3 emissions while maintaining low NOx emissions, and also reduces the emissions of N2O side reactions caused by excessive NH3 in the SCR / ASC system, achieving an effective reduction of all pollutants.

[0038] Example 2 This embodiment provides a urea injection control system applied to a dual-injection SCR system, including: The acquisition module is configured to acquire the temperature of the ufSCR in the dual-injection SCR system; The judgment module is configured to determine whether there is an NH3 leak based on the temperature and heating rate of the ufSCR. The control module is configured to reduce the urea injection rate of the ccSCR and ufSCR of the dual-injection SCR system to a set value when there is an NH3 leak, and then restore the urea injection rate of the ccSCR and ufSCR after the NH3 storage amount is less than the set minimum storage value.

[0039] It should be noted that the above modules correspond to the steps described in Embodiment 1, and the examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the content disclosed in Embodiment 1. It should also be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0040] In further embodiments, the following is also provided: An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in Embodiment 1. For brevity, further details are omitted here.

[0041] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0042] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0043] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in Embodiment 1.

[0044] The method in Example 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor. The software modules can reside in readily available storage media in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, a detailed description is not provided here.

[0045] A computer program product includes a computer program that, when executed by a processor, implements the method described in Embodiment 1.

[0046] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, which execute in a device on a target real or virtual processor to perform the processes / methods described above. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided among program modules as needed. The machine-executable instructions for the program modules can execute within a local or distributed device. In a distributed device, the program modules can reside in both local and remote storage media.

[0047] The computer program code used to implement the methods of the present invention may be written in one or more programming languages. This computer program code may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the computer or other programmable data processing device, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a computer, partially on a computer, as a stand-alone software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server.

[0048] In the context of this invention, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like. Examples of signals may include electrical, optical, radio, sound, or other forms of propagation signals, such as carrier waves, infrared signals, etc.

[0049] Those skilled in the art will recognize that the units and algorithm steps described in connection with the various examples of this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0050] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for controlling urea injection, characterized in that, Applications in dual-injection SCR systems include: Obtain the temperature of the ufSCR in the dual-jet SCR system; Determine whether there is an NH3 leak based on the temperature and heating rate of the ufSCR. When NH3 leakage occurs, the urea injection rate of the ccSCR and ufSCR in the dual-injection SCR system is reduced to the set value until the NH3 storage level is less than the set minimum storage level, at which point the urea injection rate of the ccSCR and ufSCR is restored.

2. A urea injection control method as described in claim 1, characterized in that, When the temperature of the ufSCR is greater than the set temperature threshold and the heating rate of the ufSCR is greater than the set temperature change threshold, it is determined that there is an NH3 leak.

3. A urea injection control method as described in claim 1, characterized in that, Control the urea injection rate of the ccSCR to maintain the minimum injection rate.

4. A urea injection control method as described in claim 1, characterized in that, Reduce the urea injection rate of the ufSCR to the minimum injection rate.

5. A urea injection control method as described in claim 1, characterized in that, The minimum storage value is the minimum amount of NH3 required to guarantee NOx conversion efficiency with ufSCR.

6. A urea injection control method as described in claim 1, characterized in that, After the urea injection volume of the cCSCR is brought back to normal, a small amount of over-injection is performed.

7. A urea injection control system, characterized in that, Applications in dual-injection SCR systems include: The acquisition module is configured to acquire the temperature of the ufSCR in the dual-injection SCR system; The judgment module is configured to determine whether there is an NH3 leak based on the temperature and heating rate of the ufSCR. The control module is configured to reduce the urea injection rate of the ccSCR and ufSCR of the dual-injection SCR system to a set value when there is an NH3 leak, and then restore the urea injection rate of the ccSCR and ufSCR after the NH3 storage amount is less than the set minimum storage value.

8. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the method according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, perform the method described in any one of claims 1-6.

10. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements the method described in any one of claims 1-6.

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