Urea injection quantity control method and device, electronic equipment and computer storage medium

Abstract

The invention relates to a urea injection amount control method and device, electronic equipment and a computer storage medium, and belongs to the technical field of engine tail gas purification, and the method comprises the steps that a first nitrogen oxide measured value at an inlet of an SCR system, a second nitrogen oxide measured value at an outlet of the SCR system and an ammonia concentration calculated value at the outlet of the SCR system are obtained; calculating a nitrogen oxide concentration calculation value at the outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the ammonia gas concentration calculation value, and calculating nitrogen oxide conversion efficiency based on the first nitrogen oxide concentration measurement value and the nitrogen oxide concentration calculation value; based on the SCR outlet ammonia concentration calculation value, the nitric oxide conversion efficiency calculation value and a preset nitric oxide conversion efficiency target value, a urea injection amount correction coefficient and a nitric oxide conversion efficiency correction coefficient are calculated, and the urea injection amount is adjusted. According to the method, the final urea injection control precision can be improved, and the ammonia gas leakage amount is reduced while nitrogen oxide emission is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of engine exhaust purification, and in particular to a urea injection amount control method, device, electronic equipment and computer storage medium. Background Art

[0002] With the implementation of the National VI emission regulations, the requirements for vehicle exhaust emissions are becoming increasingly higher, and commercial vehicles all use SCR (Selective Catalytic Reduction Technology) systems to treat exhaust gases.

[0003] In the existing SCR system, when urea is used to treat exhaust gas, the urea injection amount needs to be corrected according to the exhaust gas emissions. Usually, only the emission correction of nitrogen oxides is considered. The emission target of nitrogen oxides is calculated based on the corresponding relationship between the urea injection amount and the target conversion efficiency. The corresponding relationship of the target conversion efficiency is obtained through bench test calibration. The actual vehicle operation process is a transient process. This results in the nitrogen oxide emission target result obtained based on the target conversion efficiency calculation relationship being inaccurate and unable to be adjusted in real time, and thus the accurate correction of the urea injection amount cannot be guaranteed.

[0004] It can be seen that the existing SCR system cannot accurately correct the urea injection amount. Summary of the invention

[0005] In view of this, it is necessary to provide a urea injection amount control method, device, electronic equipment and computer storage medium to solve the problem that the existing SCR system cannot accurately correct the urea injection amount.

[0006] In order to solve the above problems, the present invention provides a urea injection amount control method, comprising: Obtaining a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system; Calculating a calculated value of nitrogen oxide concentration at an outlet of the SCR system based on the second measured value of nitrogen oxide concentration and the calculated value of ammonia concentration, and calculating a calculated value of nitrogen oxide conversion efficiency based on the first measured value of nitrogen oxide concentration and the calculated value of nitrogen oxide concentration; A urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient are calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value, and the urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0007] In a possible implementation manner, the calculating the calculated value of nitrogen oxide concentration at the outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated value of ammonia concentration includes: The nitrogen oxide calculation formula is used to calculate the nitrogen oxide concentration value, and the nitrogen oxide calculation formula is:

[0008] in, is the calculated value of nitrogen oxide concentration at the outlet of the SCR system, is the second nitrogen oxide concentration measurement value, is the calculated value of ammonia concentration, K is the preset sensitivity factor. In a possible implementation manner, the calculating the calculated value of nitrogen oxide conversion efficiency based on the first nitrogen oxide concentration measurement value and the calculated value of nitrogen oxide concentration includes: The nitrogen oxide conversion efficiency calculation formula is used to calculate the nitrogen oxide conversion efficiency calculation value, and the nitrogen oxide conversion rate calculation formula is:

[0009] in, is the calculated value of nitrogen oxide conversion efficiency, is the first nitrogen oxide concentration measurement value.

[0010] In a possible implementation manner, the calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated value of the ammonia concentration, the calculated value of the nitrogen oxide conversion efficiency and a preset nitrogen oxide conversion efficiency target value includes: When the calculated ammonia concentration value is greater than the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, then the nitrogen oxide conversion efficiency correction coefficient is reduced; if the calculated nitrogen oxide conversion efficiency value is greater than or equal to the nitrogen oxide conversion efficiency target value, then the urea injection amount correction coefficient is reduced; When the calculated ammonia concentration value is less than or equal to the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, the urea injection amount correction coefficient is increased; if the calculated nitrogen oxide conversion efficiency value is greater than the nitrogen oxide conversion efficiency target value, the nitrogen oxide conversion efficiency correction coefficient is increased.

[0011] In a possible implementation manner, the calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated value of the ammonia concentration, the calculated value of the nitrogen oxide conversion efficiency and a preset nitrogen oxide conversion efficiency target value includes: Calculating a nitrogen oxide conversion efficiency deviation value based on the nitrogen oxide conversion efficiency calculation value and the nitrogen oxide conversion efficiency target value; Calculating a nitrogen oxide conversion efficiency correction coefficient based on the nitrogen oxide conversion efficiency deviation value and the nitrogen oxide conversion efficiency calculation value; A urea injection amount correction coefficient is calculated based on the calculated ammonia concentration value and the nitrogen oxide conversion efficiency correction coefficient.

[0012] In a possible implementation manner, adjusting the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient includes: The target urea injection amount is calculated using a target urea injection amount calculation formula, wherein the target urea injection amount calculation formula is:

[0013] in, is the target urea injection amount, The actual ammonia storage amount of SCR is calculated based on the correction of nitrogen oxide conversion efficiency, and the corresponding urea injection amount is calculated by ammonia storage control. is the conversion coefficient between urea solution and ammonia gas, is the urea injection amount correction factor.

[0014] In a possible implementation manner, when adjusting the urea injection amount, the method further includes: determining a urea injection amount range based on a urea catalyst bed temperature and an exhaust mass flow rate of the SCR system; The urea injection amount is controlled to be within the urea injection amount range.

[0015] The present invention also provides a urea injection amount control device, comprising: A data acquisition module, used to acquire a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system; a conversion efficiency calculation module, configured to calculate a calculated value of nitrogen oxide concentration at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated value of ammonia concentration, and to calculate a calculated value of nitrogen oxide conversion efficiency based on the first nitrogen oxide concentration measurement value and the calculated value of nitrogen oxide concentration; The regulating module is used to calculate a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated value of ammonia concentration, the calculated value of nitrogen oxide conversion efficiency and a preset nitrogen oxide conversion efficiency target value, and to regulate the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0016] The present invention also provides an electronic device, comprising a memory and a processor, wherein: The memory is used to store programs; The processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps in the urea injection amount control method described in any one of the above embodiments.

[0017] The present invention also provides a computer-readable storage medium for storing a computer-readable program or instruction, wherein the program or instruction, when executed by a processor, can implement the steps in the urea injection amount control method described in any of the above embodiments.

[0018] The beneficial effects of the present invention are as follows: the urea injection amount control method provided by the present invention obtains a first nitrogen oxide concentration measurement value at the inlet of the SCR system, a second nitrogen oxide concentration measurement value at the outlet of the SCR system, and a calculated ammonia concentration value at the outlet of the SCR system, calculates the calculated nitrogen oxide concentration value at the outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, calculates the nitrogen oxide conversion efficiency calculated value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value, calculates a urea injection amount correction factor and a nitrogen oxide conversion efficiency correction factor based on the calculated ammonia concentration value, the nitrogen oxide conversion efficiency calculated value and a preset nitrogen oxide conversion efficiency target value, adjusts the urea injection amount based on the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor, adjusts the SCR urea injection amount in real time according to the actual engine working condition, and coordinates and controls the urea injection amount correction and the nitrogen oxide conversion efficiency correction based on the nitrogen oxide conversion efficiency and the ammonia leakage as control targets, and finally coordinates and corrects the total urea injection amount in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and reducing ammonia leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 A schematic flow chart of a urea injection amount control method provided by an embodiment of the present invention; Figure 2 A schematic flow chart of a correction coefficient adjustment method provided by an embodiment of the present invention; Figure 3 A flow chart of a correction coefficient control strategy provided by an embodiment of the present invention; Figure 4 A schematic diagram of a flow chart of a correction coefficient calculation method provided by an embodiment of the present invention; Figure 5 A schematic flow chart of a method for limiting urea injection amount provided in an embodiment of the present invention; Figure 6 A schematic diagram of the structure of a urea injection amount control device provided by an embodiment of the present invention; Figure 7 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0022] The descriptions of "first", "second", etc. involved in the embodiments of the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the technical features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0023] Reference to an "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] A specific embodiment of the present invention, as Figure 1 As shown, a urea injection amount control method is disclosed, comprising: S101, obtaining a first nitrogen oxide concentration measurement value at an inlet of an SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system; S102, calculating a calculated value of nitrogen oxide concentration at an outlet of the SCR system based on the second measured value of nitrogen oxide concentration and the calculated value of ammonia concentration, and calculating a calculated value of nitrogen oxide conversion efficiency based on the first measured value of nitrogen oxide concentration and the calculated value of nitrogen oxide concentration; S103, calculating a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration, the calculated nitrogen oxide conversion efficiency, and a preset nitrogen oxide conversion efficiency target value, and adjusting the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0025] In the embodiment of the present invention, the SCR system is widely used in diesel engines. The reducing agent used is urea solution. Urea is decomposed into and The working principle is to spray urea into the exhaust pipe. (nitrogen oxides) and The reaction is reduced to and , thereby reducing harmful components in diesel engine emissions , in order to ensure In order to achieve the reduction effect, excessive urea will generally be injected, resulting in excessive ammonia content in the exhaust gas, waste of urea and urea crystallization problems. Therefore, it is necessary to accurately control the urea injection amount.

[0026] In the embodiment of the present invention, in order to determine The reduction effect needs to be checked at the inlet and outlet of the SCR system. The content can be checked by arranging nitrogen oxide sensors at the inlet and outlet of the SCR system. The nitrogen oxide sensors actually detect the nitrogen oxide concentration in the exhaust gas. Therefore, a first nitrogen oxide concentration measurement value at the inlet of the SCR system and a second nitrogen oxide concentration measurement value at the outlet of the SCR system can be obtained. The calculated ammonia concentration at the outlet of the SCR system can be calculated based on the ammonia emissions under steady-state conditions, the ammonia emissions under transient conditions and the second calculated nitrogen oxide concentration value, and the present invention does not impose any limitation on this.

[0027] Furthermore, a nitrogen oxide concentration measurement value at the outlet of the SCR system is calculated based on the second nitrogen oxide concentration measurement value and the ammonia concentration calculation value, and a nitrogen oxide conversion efficiency calculation value is calculated based on the first nitrogen oxide concentration measurement value and the nitrogen oxide concentration measurement value at the SCR outlet. The specific calculation methods of the above-mentioned nitrogen oxide concentration measurement values ​​and nitrogen oxide conversion efficiency calculation values ​​are described in detail later in the present invention.

[0028] Furthermore, a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient can be calculated based on the calculated value of ammonia concentration, the calculated value of nitrogen oxide conversion efficiency and the preset nitrogen oxide conversion efficiency target value, and the urea injection amount can be adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient. The SCR urea injection amount can be adjusted in real time according to the actual engine operating condition. At the same time, based on the nitrogen oxide conversion efficiency and the ammonia leakage as control targets, the urea injection amount correction and the nitrogen oxide conversion efficiency correction are coordinated and controlled. Finally, the total urea injection amount is coordinated and corrected in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and ammonia leakage.

[0029] As a possible implementation of the present invention, in this implementation, the calculated value of nitrogen oxide concentration at the outlet of the SCR system is calculated based on the second nitrogen oxide concentration measurement value and the calculated value of ammonia concentration, including: The nitrogen oxide calculation formula is used to calculate the nitrogen oxide concentration. The nitrogen oxide calculation formula is: (1) in, is the calculated value of nitrogen oxide concentration at the outlet of the SCR system, is the second nitrogen oxide concentration measurement value, is the calculated value of ammonia concentration, K is the preset sensitivity factor.

[0030] In the embodiment of the present invention, the preset sensitivity factor K has a value range of 0.5 to 2, is linearly related to the catalyst bed temperature, generally increases with the increase of the catalyst bed temperature, and can be obtained through calibration.

[0031] Further, the nitrogen oxide conversion efficiency calculation value is calculated based on the first nitrogen oxide concentration measurement value and the SCR outlet nitrogen oxide concentration calculation value, including: The nitrogen oxide conversion efficiency calculation formula is used to calculate the nitrogen oxide conversion efficiency. The nitrogen oxide conversion rate calculation formula is: (2) in, is the calculated value of nitrogen oxide conversion efficiency, is the first nitrogen oxide concentration measurement value.

[0032] The embodiment of the present invention calculates the calculated value of the nitrogen oxide conversion efficiency through a formula to ensure the accuracy of the calculated value of the nitrogen oxide conversion efficiency.

[0033] As a possible implementation mode of the present invention, in this implementation mode, Figure 2 As shown, the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor are calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value and the preset nitrogen oxide conversion efficiency target value, including: S201, when the calculated ammonia concentration value is greater than the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, then reduce the nitrogen oxide conversion efficiency correction coefficient; if the calculated nitrogen oxide conversion efficiency value is greater than or equal to the nitrogen oxide conversion efficiency target value, then reduce the urea injection amount correction coefficient; S202, when the calculated ammonia concentration is less than or equal to the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency is less than the target nitrogen oxide conversion efficiency, the urea injection amount correction coefficient is increased; if the calculated nitrogen oxide conversion efficiency is greater than the target nitrogen oxide conversion efficiency, the nitrogen oxide conversion efficiency correction coefficient is reduced.

[0034] In the embodiment of the present invention, the adjustment strategy of the nitrogen oxide conversion efficiency correction coefficient and the urea injection amount correction coefficient in the urea injection amount control can be determined based on the calculated value of the ammonia concentration at the outlet of the SCR system in the above-mentioned embodiment, the calculated value of the nitrogen oxide conversion efficiency and the preset nitrogen oxide conversion efficiency target value. Specifically, Figure 3 As shown, after obtaining the calculated value of ammonia concentration at the outlet of the SCR system, the calculated value of nitrogen oxide conversion efficiency and the preset nitrogen oxide conversion efficiency target value, it is first determined whether the calculated value of ammonia concentration is greater than the preset ammonia concentration threshold.

[0035] When the calculated ammonia concentration is less than or equal to the preset ammonia concentration threshold, determine whether the calculated nitrogen oxide conversion efficiency is less than the target nitrogen oxide conversion efficiency value; if the calculated nitrogen oxide conversion efficiency is less than the target nitrogen oxide conversion efficiency value, increase the urea injection amount correction factor; if the calculated nitrogen oxide conversion efficiency is greater than the target nitrogen oxide conversion efficiency value, increase the nitrogen oxide conversion efficiency correction factor.

[0036] When the calculated ammonia concentration value is less than or equal to the preset ammonia concentration threshold, the relationship between the calculated nitrogen oxide conversion efficiency value and the target nitrogen oxide conversion efficiency value is determined. If the calculated nitrogen oxide conversion efficiency value is less than the target nitrogen oxide conversion efficiency value, the urea injection amount correction factor is increased; if the calculated nitrogen oxide conversion efficiency value is greater than the target nitrogen oxide conversion efficiency value, the nitrogen oxide conversion efficiency correction factor is increased; if the calculated nitrogen oxide conversion efficiency value is equal to the target nitrogen oxide conversion efficiency value, the nitrogen oxide conversion efficiency correction factor and the urea injection amount correction factor are kept unchanged.

[0037] The detailed adjustment strategy of the nitrogen oxide conversion efficiency correction coefficient and the urea injection amount correction coefficient provided in the embodiment of the present invention ensures the accuracy of the adjustment of the nitrogen oxide conversion efficiency correction coefficient and the urea injection amount correction coefficient.

[0038] As a possible implementation mode of the present invention, in this implementation mode, Figure 4 As shown, the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor are calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value and the preset nitrogen oxide conversion efficiency target value, including: S401, calculating a nitrogen oxide conversion efficiency deviation value based on a nitrogen oxide conversion efficiency calculation value and a nitrogen oxide conversion efficiency target value; S402, calculating a nitrogen oxide conversion efficiency correction coefficient based on the nitrogen oxide conversion efficiency deviation value and the nitrogen oxide conversion efficiency calculation value; S403: Calculate a urea injection amount correction coefficient based on the calculated ammonia concentration and the nitrogen oxide conversion efficiency correction coefficient.

[0039] In the embodiment of the present invention, if the ammonia leakage is high and The calculated conversion efficiency is less than The conversion efficiency model calculated value should reduce the actual ammonia storage The conversion efficiency correction factor (actual ammonia storage amount increases) reduces the final urea injection amount and further reduces the ammonia leakage at the SCR outlet; if the ammonia leakage is high and The calculated transformation efficiency is equal to The conversion efficiency model calculation value should reduce the correction coefficient of urea injection amount, reduce the final urea injection amount, and further reduce the ammonia leakage at the SCR outlet; if the ammonia leakage is high and The calculated conversion efficiency is greater than The conversion efficiency model calculation value should reduce the correction factor of urea injection amount, reduce the final urea injection amount, and further reduce the ammonia leakage at the SCR outlet; if the ammonia leakage is low (the leakage is appropriate), and The calculated conversion efficiency is less than The conversion efficiency model calculation value should increase the urea injection amount correction coefficient, increase the final urea injection amount, and further improve Calculated conversion efficiency; if the ammonia leakage is low and The calculated transformation efficiency is equal to The conversion efficiency model calculates the value, maintaining the urea injection amount and The correction factor of conversion efficiency remains unchanged; if the ammonia leakage is low and The calculated conversion efficiency is greater than The conversion efficiency model calculated value should increase the actual ammonia storage The conversion efficiency correction factor (actual ammonia storage amount is reduced) increases the final urea injection amount and further improves Calculated conversion efficiency, reaching the target Conversion efficiency.

[0040] The specific calculation logic for the nitrogen oxide conversion efficiency correction factor and the urea injection amount correction factor is as follows: The nitrogen oxide conversion efficiency deviation is calculated using formula (3): (3) in, is the nitrogen oxide conversion efficiency deviation value, is the calculated value of nitrogen oxide conversion efficiency, is the model calculated value of nitrogen oxide conversion efficiency, which can be obtained through model calculation.

[0041] Then, based on the relationship between the calculated value of the nitrogen oxide conversion efficiency and the calculated value of the nitrogen oxide conversion efficiency model, a value is assigned to the nitrogen oxide conversion efficiency correction coefficient, wherein the assigned nitrogen oxide conversion efficiency correction coefficient can be obtained by calibration based on the nitrogen oxide conversion efficiency deviation value, and the nitrogen oxide conversion efficiency correction coefficient under different working conditions satisfies formula (4): (4) in, is the NOx conversion efficiency correction factor when the calculated NOx conversion efficiency is equal to the NOx conversion efficiency target value, is the NOx conversion efficiency correction factor when the calculated NOx conversion efficiency is less than the NOx conversion efficiency target value, is the NOx conversion efficiency correction factor when the calculated NOx conversion efficiency is greater than the NOx conversion efficiency target value, and The default calculation rules.

[0042] Based on the calculated value of ammonia leakage, the ammonia leakage correction coefficient can be calculated. The assigned ammonia leakage correction coefficient can be calibrated based on the calculated value of ammonia leakage. The ammonia leakage correction coefficient under different working conditions satisfies formula (5): (5) in, For SCR export Calculated leakage value, for Correction factor for higher leakage, for Correction factor when the leakage meets regulatory requirements, The default calculation rules.

[0043] Furthermore, as shown in Table 1, the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor can be calculated:

[0044] in, (6) (7) (8) (9) in, and is the urea injection amount correction coefficient, and is the correction factor for the nitrogen oxide conversion efficiency. Furthermore, the urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient, including: The target urea injection amount is calculated using a target urea injection amount calculation formula, wherein the target urea injection amount calculation formula is: (10) in, is the target urea injection amount, The actual ammonia storage amount of SCR is calculated based on the correction of nitrogen oxide conversion efficiency, and the corresponding urea injection amount is calculated by ammonia storage control. is the conversion coefficient between urea solution and ammonia gas, is the urea injection amount correction factor.

[0045] In the embodiment of the present invention, the corresponding corrected urea injection amount can be determined based on the nitrogen oxide conversion efficiency correction coefficient calculated in the above embodiment, and then the target urea injection amount is calculated based on the corrected urea injection amount, the conversion coefficient of urea solution and ammonia, and the urea injection amount correction coefficient, wherein the conversion coefficient of urea solution and ammonia is It is related to the urea concentration. The basic conversion coefficient of 32.5% urea solution and ammonia is 0.174. The actual conversion coefficient can be corrected based on the exhaust temperature.

[0046] The embodiment of the present invention takes both nitrogen oxide conversion efficiency and ammonia leakage as control targets, coordinates and controls the urea injection amount correction and the nitrogen oxide conversion efficiency correction, and finally coordinates and corrects the total urea injection amount in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and ammonia leakage.

[0047] As a possible implementation mode of the present invention, in this implementation mode, Figure 5 As shown, when adjusting the urea injection amount, it also includes: S501, determining a urea injection amount range based on a urea catalyst bed temperature and an exhaust mass flow rate of an SCR system; S502, controlling the urea injection amount to be within a urea injection amount range.

[0048] In the embodiment of the present invention, before the urea injection system is controlled to inject urea according to the calculated urea injection amount correction coefficient, in order to protect the urea nozzle and prevent urea overspray and crystallization at low temperature, the minimum and maximum limits of the urea injection amount are required. Specifically, the upper limit of the urea injection amount under the current working condition can be determined according to the catalyst bed temperature and the exhaust mass flow rate. When the urea injection amount is greater than the upper limit, in order to avoid ammonia leakage and urea crystallization caused by urea overspray, the urea injection amount is limited to the upper limit. When the catalyst bed temperature is lower than 200°C, the upper limit of the urea injection amount is set to 0, and the urea injection is stopped; when the catalyst bed temperature is higher than 200°C, the upper limit of the urea injection amount increases with the increase of the catalyst bed temperature and the exhaust mass flow rate. In addition, the lower limit of the urea injection amount under the current working condition is determined according to the catalyst bed temperature and the exhaust mass. When the urea injection amount is less than the limit, in order to avoid the urea nozzle being damaged by the injection of urea at a small flow rate, the urea injection should be stopped.

[0049] The embodiment of the present invention sets the upper and lower limits of the urea injection amount to prevent the urea nozzle from being damaged by overspray of urea or too low a urea flow rate.

[0050] In order to better implement the urea injection amount control method in the embodiment of the present invention, based on the urea injection amount control method, correspondingly, Figure 6 As shown, the embodiment of the present invention further provides a urea injection amount control device, and the urea injection amount control device 600 includes: A data acquisition module 601 is used to acquire a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system; a conversion efficiency calculation module 602, configured to calculate a calculated value of nitrogen oxide concentration at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated value of ammonia concentration, and to calculate a calculated value of nitrogen oxide conversion efficiency based on the first nitrogen oxide concentration measurement value and the calculated value of nitrogen oxide concentration; The adjustment module 603 is used to calculate the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated value of ammonia concentration, the calculated value of nitrogen oxide conversion efficiency and the preset nitrogen oxide conversion efficiency target value, and adjust the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0051] The urea injection amount control device 600 provided in the above embodiment can implement the technical solution described in the above urea injection amount control method embodiment. The specific implementation principles of the above modules or units can refer to the corresponding contents in the above urea injection amount control method embodiment, which will not be repeated here.

[0052] The urea injection amount control device provided by the present invention takes the nitrogen oxide conversion efficiency and the ammonia leakage as control targets, coordinates and controls the urea injection amount correction and the nitrogen oxide conversion efficiency correction, and finally coordinates and corrects the total urea injection amount in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and ammonia leakage.

[0053] like Figure 7 As shown, the present invention also provides an electronic device 700. The electronic device 700 includes a processor 701, a memory 702 and a display 703. Figure 7 Only some components of the electronic device 700 are shown, but it should be understood that it is not required to implement all of the components shown, and more or fewer components may be implemented instead.

[0054] In some embodiments, the processor 701 may be a central processing unit (CPU), a microprocessor or other data processing chip, and is used to run program codes or process data stored in the memory 702, such as the urea injection amount control method of the present invention.

[0055] In some embodiments, the processor 701 may be a single server or a server group. The server group may be centralized or distributed.

[0056] In some embodiments, the memory 702 may be an internal storage unit of the electronic device 700, such as a hard disk or a memory of the electronic device 700. The memory 702 is used to store application software installed in the electronic device 700 and various data.

[0057] In some embodiments, when the processor 701 executes the urea injection amount control program in the memory 702, the following steps may be implemented: Obtaining a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system; Calculating a calculated value of nitrogen oxide concentration at an outlet of the SCR system based on the second measured value of nitrogen oxide concentration and the calculated value of ammonia concentration, and calculating a calculated value of nitrogen oxide conversion efficiency based on the first measured value of nitrogen oxide concentration and the calculated value of nitrogen oxide concentration; A urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient are calculated based on the calculated ammonia concentration, the calculated nitrogen oxide conversion efficiency and a preset nitrogen oxide conversion efficiency target value, and the urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0058] It should be understood that: when the processor 701 executes the urea injection amount control program in the memory 702 , in addition to the above functions, other functions may also be implemented, and details may refer to the description of the corresponding method embodiments above.

[0059] Accordingly, an embodiment of the present invention further provides a computer-readable storage medium, which is used to store computer-readable programs or instructions. When the programs or instructions are executed by a processor, the steps or functions of the urea injection amount control method provided in the above-mentioned method embodiments can be implemented.

[0060] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for controlling urea injection amount, characterized in that: include: Obtaining a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system; Calculating a calculated value of nitrogen oxide concentration at an outlet of the SCR system based on the second measured value of nitrogen oxide concentration and the calculated value of ammonia concentration, and calculating a calculated value of nitrogen oxide conversion efficiency based on the first measured value of nitrogen oxide concentration and the calculated value of nitrogen oxide concentration; A urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient are calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value, and the urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

2. The urea injection amount control method according to claim 1, characterized in that: The calculating the calculated value of nitrogen oxide concentration at the outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated value of ammonia concentration includes: The nitrogen oxide calculation formula is used to calculate the nitrogen oxide concentration value, and the nitrogen oxide calculation formula is: in, is the calculated value of nitrogen oxide concentration at the outlet of the SCR system, is the second nitrogen oxide concentration measurement value, is the calculated value of ammonia concentration, K is the preset sensitivity factor.

3. The urea injection amount control method according to claim 2, characterized in that: The calculating of the nitrogen oxide conversion efficiency calculated value based on the first nitrogen oxide concentration measured value and the nitrogen oxide concentration calculated value includes: The nitrogen oxide conversion efficiency calculation formula is used to calculate the nitrogen oxide conversion efficiency calculation value, and the nitrogen oxide conversion rate calculation formula is: in, is the calculated value of nitrogen oxide conversion efficiency, is the first nitrogen oxide concentration measurement value.

4. The urea injection amount control method according to claim 1, characterized in that: The calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the ammonia concentration calculation value, the nitrogen oxide conversion efficiency calculation value and the preset nitrogen oxide conversion efficiency target value includes: When the calculated ammonia concentration value is greater than the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, then the nitrogen oxide conversion efficiency correction coefficient is reduced; if the calculated nitrogen oxide conversion efficiency value is greater than or equal to the nitrogen oxide conversion efficiency target value, then the urea injection amount correction coefficient is reduced; When the calculated ammonia concentration value is less than or equal to the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, the urea injection amount correction coefficient is increased; if the calculated nitrogen oxide conversion efficiency value is greater than the nitrogen oxide conversion efficiency target value, the nitrogen oxide conversion efficiency correction coefficient is increased.

5. The urea injection amount control method according to claim 4, characterized in that: The calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the ammonia concentration calculation value, the nitrogen oxide conversion efficiency calculation value and the preset nitrogen oxide conversion efficiency target value includes: Calculating a nitrogen oxide conversion efficiency deviation value based on the nitrogen oxide conversion efficiency calculation value and the nitrogen oxide conversion efficiency target value; Calculating a nitrogen oxide conversion efficiency correction coefficient based on the nitrogen oxide conversion efficiency deviation value and the nitrogen oxide conversion efficiency calculation value; A urea injection amount correction coefficient is calculated based on the calculated ammonia concentration value and the nitrogen oxide conversion efficiency correction coefficient.

6. The urea injection amount control method according to claim 4, characterized in that: The step of adjusting the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient includes: The target urea injection amount is calculated using a target urea injection amount calculation formula, wherein the target urea injection amount calculation formula is: in, is the target urea injection amount, The actual ammonia storage amount of SCR is calculated based on the correction of nitrogen oxide conversion efficiency, and the corresponding urea injection amount is calculated by ammonia storage control. is the conversion coefficient between urea solution and ammonia, is the urea injection amount correction factor.

7. The urea injection amount control method according to claim 6, characterized in that: When adjusting the urea injection amount, it also includes: determining a urea injection amount range based on a urea catalyst bed temperature and an exhaust mass flow rate of the SCR system; The urea injection amount is controlled to be within the urea injection amount range.

8. A urea injection amount control device, characterized in that: include: A data acquisition module, used to acquire a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system; a conversion efficiency calculation module, configured to calculate a calculated value of nitrogen oxide concentration at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated value of ammonia concentration, and to calculate a calculated value of nitrogen oxide conversion efficiency based on the first nitrogen oxide concentration measurement value and the calculated value of nitrogen oxide concentration; The regulating module is used to calculate a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated value of ammonia concentration, the calculated value of nitrogen oxide conversion efficiency and a preset nitrogen oxide conversion efficiency target value, and to regulate the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

9. An electronic device, characterized in that: comprising a memory and a processor, wherein: The memory is used to store programs; The processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps of the urea injection amount control method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: Used to store computer-readable programs or instructions, which, when executed by a processor, can implement the steps of the urea injection amount control method described in any one of claims 1 to 7.

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