System and method for rapid diagnosis of sulfur poisoning of scr catalysts

Abstract

The application discloses a kind of SCR catalyst sulfur poisoning quick diagnosis system and method, SCR catalyst sulfur poisoning quick diagnosis system includes sulfur poisoning diagnosis model, the sulfur poisoning diagnosis model includes sequentially connected one SCR model, one front temperature sensor fault diagnosis module, one rear temperature sensor fault diagnosis module, one front NO X Sensor fault diagnosis module, one rear NO X Sensor fault diagnosis module, one urea pump fault diagnosis module and one sulfur poisoning model.The present application can be realized when SCR fails, to be able to identify in time, and can accurately judge whether sulfur poisoning occurs, so as to solve the problems that the existing sulfur poisoning diagnosis technology is not timely or has high error rate, and the sulfur poisoning phenomenon cannot be identified in the first time, and the reliability is not high.

Description

Technical Field

[0001] This invention relates to the field of diesel engine exhaust aftertreatment technology, and in particular to a rapid diagnostic system and method for sulfur poisoning of SCR (Selective Catalytic Reduction, SCR) catalysts. Background Technology

[0002] Diesel engine exhaust contains a large amount of nitrogen oxides, which, if left untreated, will pollute the environment. Natural disasters such as acid rain and photochemical smog are consequences of excessive nitrogen oxide emissions. With increasingly stringent emission regulations, SCR systems are generally used to treat exhaust gases to meet emission requirements. This involves introducing ammonia gas into the exhaust gas under the action of an SCR catalyst, thereby catalytically reducing nitrogen oxides. The catalytic reduction reactions that occur mainly include the following two:

[0003] Standard SCR reaction: 4NO + 4NH3 + O2 → 4N2 + 6H2O

[0004] Fast SCR reaction: NO + NO₂ + 2NH₃ → 2N₂ + 3H₂O

[0005] However, diesel engines often use diesel fuel with high sulfur content, which frequently produces sulfur oxides such as sulfur dioxide and sulfur trioxide upon combustion. These sulfur oxides react with the active sites on catalysts, especially copper-based catalysts, causing deactivation and resulting in "sulfur poisoning." Sulfur poisoning significantly affects catalyst activity. While sulfur-poisoned catalysts can generally be reactivated by heating, prolonged sulfur poisoning can lead to permanent deactivation of some catalysts, resulting in irreversible sulfur poisoning. This significantly weakens the catalytic effect of SCR reactions, causing severe environmental pollution and substantial economic losses. Therefore, accurate identification of sulfur poisoning in its early stages is crucial.

[0006] Existing sulfur poisoning diagnostic technologies all suffer from problems such as untimely diagnosis or high diagnostic error rates, which prevent sulfur poisoning from being identified in the first instance and result in low reliability. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings and defects of the prior art and to provide a rapid diagnostic system and method for sulfur poisoning of SCR catalysts.

[0008] A first aspect of the present invention provides a rapid diagnostic system for sulfur poisoning of SCR catalysts, applied to the determination of sulfur poisoning in vehicle emission aftertreatment devices (SCRs). The system includes a sulfur poisoning diagnostic model comprising, in sequence, an SCR model, a front temperature sensor fault diagnosis module, a rear temperature sensor fault diagnosis module, and a front NOx sensor. X Sensor fault diagnosis module, a rear NO X A sensor fault diagnosis module, a urea pump fault diagnosis module, and a sulfur poisoning model;

[0009] The SCR model includes four reactions: ammonia adsorption catalyst reaction, ammonia desorption catalyst reaction, oxidation reaction, and SCR reaction. The SCR input parameters to the model include exhaust gas volumetric flow rate (SCR system inlet flow rate), catalyst volume, catalyst outlet temperature, SCR inlet temperature, nitrogen oxide inlet concentration, ammonia inlet concentration, pre-exponential factors and activation energies of the four reactions, initial catalyst ammonia coverage, and ambient temperature. After calculation, the SCR model outputs the catalyst ammonia coverage, nitrogen oxide outlet concentration, ammonia outlet concentration, and catalyst outlet temperature after the reaction.

[0010] The front temperature sensor fault diagnosis module is used to diagnose whether the temperature sensor at the SCR catalyst inlet is malfunctioning based on the calculated actual temperature at the SCR catalyst inlet; the rear temperature sensor fault diagnosis module is used to diagnose whether the temperature sensor at the SCR catalyst outlet is malfunctioning based on the catalyst outlet temperature calculated in the SCR model; the front NO x Sensor fault diagnosis module, used for detecting NO upstream of the catalyst X Rapid calculation results of NO concentration at the SCR catalyst inlet. X Diagnose whether the sensor has malfunctioned; the subsequent NO X The sensor fault diagnosis module is used to diagnose whether the NOx sensor at the SCR catalyst outlet is malfunctioning based on the nitrogen oxide concentration calculated in the SCR model; the urea pump fault diagnosis module is used to diagnose whether the urea pump injection process is malfunctioning, including determining whether the nozzle is blocked based on the urea pump nozzle cross-sectional coefficient k0 and diagnosing whether the urea injection is excessive based on the ammonia coverage and the ammonia leakage amount collected downstream.

[0011] The sulfur poisoning model, based on chemical reaction kinetics calculations, diagnoses sulfur poisoning. It includes three reactions: sulfur dioxide adsorption, reversible sulfur poisoning, and irreversible sulfur poisoning, as well as a set of preset sulfur oxide concentrations. Parameters input to the model include the start and end times of the call, catalyst volume, reaction temperature, nitrogen oxide inlet concentration, ammonia inlet concentration, pre-reaction ammonia coverage on the catalyst, pre-exponential factors for the three reactions, and activation energies. The model calculates the changes in ammonia coverage on the SCR catalyst surface over a historical period under different virtual SO2 concentrations, and then uses these changes to determine NO2 levels. X Emissions forecast; if NO is at all predetermined SO2 concentrations... X If the predicted emission accuracy does not meet the set threshold, the diagnostic session ends, and engine exhaust monitoring continues; if the predicted SO2 virtual concentration is below the threshold, NO... X If the emission prediction accuracy meets the set threshold, then the NO emission prediction for the future period will continue to be calculated based on this virtual SO2 concentration. X The emissions were compared with the actual situation, and if future NO emissions... X Actual emissions and NO X If the predicted emissions match, then sulfur poisoning is determined to have occurred.

[0012] The aforementioned front temperature sensor fault diagnosis module includes a temperature MAP, which is used to quickly calculate the actual temperature at the SCR catalyst inlet and compare the result with the sensor temperature to determine whether the sensor is faulty.

[0013] The diagnostic method of the post-temperature sensor fault diagnosis module is to extract the catalyst outlet temperature calculated in the SCR model and compare it with the sensor temperature to determine whether the sensor is faulty.

[0014] The aforementioned NOx sensor fault diagnosis module is used to establish a MAP between the NOx concentration upstream of the catalyst and the engine operating conditions, to quickly calculate the NOx concentration upstream of the catalyst, and to compare the result with the sensor concentration to determine whether the sensor is faulty.

[0015] Among them, the post-NO X The sensor fault diagnosis module diagnoses by extracting the nitrogen oxide concentration calculated from the SCR model and comparing it with the sensor concentration to determine whether the sensor is faulty.

[0016] The urea pump fault diagnosis module includes a urea pump nozzle blockage diagnosis unit and a urea injection over-dose diagnosis unit, each used to diagnose whether the nozzle is blocked and whether the urea injection is excessive.

[0017] The urea pump nozzle blockage diagnosis unit is used to calculate the urea pump nozzle section coefficient k0 based on the ammonia concentration at the catalyst inlet and the mass flow rate of the urea solution injection. When k0 is lower than the threshold, the nozzle is diagnosed as blocked.

[0018] The urea injection overdose diagnostic unit is used to analyze the combined ammonia coverage rate and the ammonia leakage amount collected downstream. When both exceed the set threshold, it is diagnosed as urea injection overdose.

[0019] The concentration of sulfur oxides ranges from 100 ppm to 1000 ppm.

[0020] A second aspect of the present invention provides a rapid diagnostic method for sulfur poisoning of SCR catalysts, implemented based on the rapid diagnostic system for sulfur poisoning of SCR catalysts described in the first aspect of the present invention. During vehicle operation, the ECU continuously monitors the NOx conversion rate. When the ECU detects a decrease in the NOx conversion rate of the SCR, it records this moment and introduces the data for the next moment. If no abnormality occurs within a continuous first preset time period, the call process ends. When the NOx conversion rate is below 85% for more than 75% of the moments within a second preset time period, the diagnostic process begins.

[0021] Ammonia coverage, NOx concentration, ammonia concentration, and catalyst outlet temperature were calculated using an SCR model. When the catalyst outlet temperature was below 200°C, NO was confirmed to be... X The low conversion rate is caused by temperature, so the diagnostic process is interrupted. If the catalyst outlet temperature is above 200℃, the front and rear temperature sensor fault diagnosis modules are called. If a temperature sensor fault is diagnosed, an error is reported to the ECU and the diagnostic process is interrupted. If the temperature sensor is not faulty, the front NO... X Sensor fault diagnosis module and post-NO X The sensor fault diagnosis module, if it diagnoses NO... X If the sensor malfunctions, an error is reported to the ECU and the diagnostic process is interrupted; if NO... X If the sensor is not faulty, the urea pump fault diagnosis module is invoked to diagnose nozzle blockage and excessive urea injection faults respectively. If a urea pump fault is diagnosed, an error is reported to the ECU and the diagnosis process is terminated. If the fault location cannot be determined, the sulfur poisoning model is invoked for diagnosis.

[0022] The sulfur poisoning model contains multiple preset SO2 concentrations. Calculations are performed to determine the occupancy of active sites on the catalyst surface under different SO2 concentrations when sulfur poisoning occurs. The result is multiplied by the ammonia coverage rate originally input into the SCR model and used as the new ammonia coverage rate input to the SCR model. The SCR model is then called again for calculation with the new input. If the change in nitrogen oxide concentration calculated using the new ammonia coverage rate at a certain preset SO2 concentration matches the actual value, sulfur poisoning is diagnosed. In this case, the actual SO2 concentration is closest to the corresponding preset SO2 concentration.

[0023] This invention enables timely identification of SCR malfunctions and accurate determination of whether sulfur poisoning has occurred. This solves the problems of untimely diagnosis or high error rate in existing sulfur poisoning diagnosis technologies, which prevent the timely identification of sulfur poisoning and have low reliability. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the rapid diagnostic system for sulfur poisoning in SCR catalysts according to the present invention.

[0025] Figure 2 This is a schematic diagram of the diagnostic process call of the SCR catalyst sulfur poisoning rapid diagnostic system of the present invention.

[0026] Figure 3 This is a schematic diagram of the working process of the sulfur poisoning model in the rapid diagnosis system for sulfur poisoning of SCR catalysts of the present invention.

[0027] Figure 4 This is a schematic diagram of parameter transfer between the SCR model and the sulfur poisoning model of the present invention.

[0028] In the picture:

[0029] 1-SCR model, 2-Front temperature sensor fault diagnosis module, 3-Rear temperature sensor fault diagnosis module, 4-Front NOx sensor fault diagnosis module, 5-Rear NOx sensor fault diagnosis module, 6-Urea pump fault diagnosis module, 7-Sulfur poisoning model. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0031] The rapid diagnostic system for sulfur poisoning of SCR catalyst of the present invention can identify SCR malfunctions in a timely manner, eliminate common SCR malfunctions such as sensor malfunctions and urea pump malfunctions, and accurately determine whether sulfur poisoning has occurred.

[0032] like Figure 1As shown, in a first aspect of the present invention, a rapid diagnostic system for sulfur poisoning of an SCR catalyst is provided, which is applied to the determination of sulfur poisoning in a vehicle emission aftertreatment device (SCR). The system includes a sulfur poisoning diagnostic model, comprising, in sequence, an SCR model, a front temperature sensor fault diagnosis module, a rear temperature sensor fault diagnosis module, and a front NOx sensor... X Sensor fault diagnosis module, a rear NO X A sensor fault diagnosis module, a urea pump fault diagnosis module, and a sulfur poisoning model;

[0033] The SCR model includes four reactions: ammonia adsorption catalyst reaction, ammonia desorption catalyst reaction, oxidation reaction, and SCR reaction. The SCR input parameters to the model include tail gas volumetric flow rate, catalyst volume, catalyst outlet temperature, SCR inlet temperature, nitrogen oxide inlet concentration, ammonia inlet concentration, pre-exponential factors and activation energies of the four reactions, initial catalyst ammonia coverage, and ambient temperature. Through calculation, the SCR model outputs the catalyst ammonia coverage, nitrogen oxide outlet concentration, ammonia outlet concentration, and catalyst outlet temperature after the reaction.

[0034] The front temperature sensor fault diagnosis module is used to diagnose whether the temperature sensor at the SCR catalyst inlet is malfunctioning based on the calculated actual temperature at the SCR catalyst inlet; the rear temperature sensor fault diagnosis module is used to diagnose whether the temperature sensor at the SCR catalyst outlet is malfunctioning based on the catalyst outlet temperature calculated in the SCR model; the front NO x The sensor fault diagnosis module is used to diagnose whether the NOx sensor at the SCR catalyst inlet is malfunctioning based on the rapid calculation results of the NOx concentration upstream of the catalyst; the subsequent NO... X The sensor fault diagnosis module is used to diagnose whether the NOx sensor at the SCR catalyst outlet is malfunctioning based on the nitrogen oxide concentration calculated in the SCR model; the urea pump fault diagnosis module is used to diagnose whether the urea pump injection process is malfunctioning, including determining whether the nozzle is blocked based on the urea pump nozzle cross-sectional coefficient k0 and diagnosing whether the urea injection is excessive based on the ammonia coverage and the ammonia leakage amount collected downstream.

[0035] The sulfur poisoning model includes three reactions: sulfur dioxide adsorption reaction, reversible sulfur poisoning reaction, and irreversible sulfur poisoning reaction, as well as a set of preset concentrations of sulfur oxides (SO2). The parameters input into the sulfur poisoning model include the start time, end time, catalyst volume, SCR temperature, nitrogen oxide inlet concentration, ammonia inlet concentration, initial catalyst ammonia coverage, pre-exponential factors of the three reactions, and activation energies.

[0036] The sulfur toxicity model is based on the input SCR temperature and inlet NO. X Information such as concentration, inlet NH3 concentration, initial catalyst ammonia coverage, and catalyst volume, combined with a preset SO2 concentration, is used to calculate the change in ammonia coverage on the catalyst surface when sulfur poisoning occurs at different SO2 concentrations within a certain time period, so as to reflect the degree of sulfur poisoning of the catalyst under different SO2 concentrations.

[0037] The sulfur poisoning model and the SCR model are linked by the catalyst ammonia coverage ratio. The sulfur poisoning model uses receiving temperature, NH3 concentration, and NO... X The actual measured engine data, such as concentration, are combined with the pre-set SO2 concentration for calculation, and the results are then returned to the SCR model in the form of ammonia coverage.

[0038] In specific implementation, the sulfur poisoning model calculates the changes in ammonia coverage on the SCR catalyst surface over a historical period under different virtual SO2 concentrations, and then performs NO testing based on these changes. X Emissions forecast; if NO is at all predetermined SO2 concentrations... X If the predicted emission accuracy does not meet the set threshold, the diagnostic session ends, and engine exhaust monitoring continues; if the predicted SO2 virtual concentration is below the threshold, NO... X If the emission prediction accuracy meets the set threshold, then the NO emission prediction for the future period will continue to be calculated based on this virtual SO2 concentration. X The emissions were compared with the actual situation, and if future NO emissions... X Actual emissions and NO X If the predicted emissions match, then sulfur poisoning is determined to have occurred.

[0039] In this invention, the sulfur poisoning model includes a reversible sulfur poisoning module and an irreversible sulfur poisoning module, and calculations are performed separately for reversible and irreversible sulfur poisoning. Reversible sulfur poisoning refers to the reaction of SO2 on the surface of active sites with NH3 to form easily decomposable sulfates; this type of sulfur poisoning can be reversed by heating or other methods. Here, a copper-based catalyst is used as an example for the reversible sulfur poisoning reaction:

[0040]

[0041] S1 represents the active site on the surface of the copper-based catalyst. In actual sulfur poisoning processes, reversible sulfur poisoning has the greatest impact and the most obvious effect in the shortest time.

[0042] Irreversible sulfur poisoning occurs when SO2 reacts with catalyst components in the presence of a catalyst to form non-decomposable metal sulfates. Here, we will still use a copper-based catalyst as an example:

[0043]

[0044] In the SCR reaction, although reversible and irreversible sulfur poisoning differ in degree, they do not occur sequentially; these two reactions happen simultaneously and in parallel. Therefore, these two modules are calculated separately in the model to determine the number of catalyst surface active sites affected by reversible and irreversible sulfur poisoning, respectively. These results are then summed and used as the overall output as the rate of change in catalyst ammonia coverage.

[0045] It should be noted that there are several different descriptions of the current sulfur poisoning mechanism. This paper only uses one of the descriptions as the basis for building the sulfur poisoning model, and it is by no means a limitation on the present invention.

[0046] The diagnostic system of this invention can be pre-installed on a vehicle, and the SCR model runs synchronously while the engine is running. When the nitrogen oxide conversion rate in the exhaust gas remains stable, the SCR model runs synchronously with the engine, performing real-time calculations and model result verification. When an increase in the nitrogen oxide content in the engine exhaust exceeding a threshold is detected, the sulfur poisoning model is invoked using the SCR model to determine sulfur poisoning.

[0047] The aforementioned front temperature sensor fault diagnosis module includes a temperature MAP, which is used to quickly calculate the actual temperature at the SCR catalyst inlet and compare the result with the sensor temperature to determine whether the sensor is faulty.

[0048] The diagnostic method of the post-temperature sensor fault diagnosis module is to extract the catalyst outlet temperature calculated in the SCR model and compare it with the sensor temperature to determine whether the sensor is faulty.

[0049] Among them, the former NO x Sensor fault diagnosis module, used for NO upstream of catalyst X A MAP is established between the concentration and engine operating conditions to quickly calculate the NOx concentration upstream of the catalyst. The results are then compared with the sensor concentration to determine if the sensor is faulty.

[0050] The diagnostic method of the post-NOX sensor fault diagnosis module is to extract the nitrogen oxide concentration calculated in the SCR model and compare it with the sensor concentration to determine whether the sensor is faulty.

[0051] The urea pump fault diagnosis module includes a urea pump nozzle blockage diagnosis unit and a urea injection over-dose diagnosis unit, each used to diagnose whether the nozzle is blocked and whether the urea injection is excessive.

[0052] The urea pump nozzle blockage diagnosis unit is used to calculate the urea pump nozzle section coefficient k0 based on the ammonia concentration at the catalyst inlet and the mass flow rate of the urea solution injection. When k0 is lower than the threshold, the nozzle is diagnosed as blocked.

[0053] The urea injection overdose diagnostic unit is used to analyze the combined ammonia coverage rate and the ammonia leakage amount collected downstream. When both exceed the set threshold, it is diagnosed as urea injection overdose.

[0054] The concentration of sulfur oxides ranges from 100 ppm to 1000 ppm.

[0055] A second aspect of this invention provides a rapid diagnostic method for sulfur poisoning in SCR catalysts, implemented based on the rapid diagnostic system for sulfur poisoning in SCR catalysts described in the first aspect of this invention. During vehicle operation, the ECU continuously monitors NO... X Conversion rate monitoring. When the ECU detects NO from the SCR... x When the conversion rate drops, first record this moment, then import the data from the next moment. If no anomalies occur for 30 consecutive seconds, end the call process; if more than 75% of the moments within 10 minutes show NO... x If the conversion rate is below 85%, the diagnostic process will be initiated.

[0056] The diagnostic process of this invention is as follows: First, the ammonia coverage, nitrogen oxide concentration, ammonia concentration, and catalyst outlet temperature are calculated using the SCR model. When the catalyst outlet temperature is below 200°C, it is confirmed that the low NOx conversion rate is caused by temperature, and the diagnostic process is interrupted. If the catalyst outlet temperature is above 200°C, the front temperature sensor fault diagnosis module and the rear temperature sensor fault diagnosis module are called. If a temperature sensor fault is diagnosed, an error is reported to the ECU, and the diagnostic process is interrupted. If the temperature sensor is not faulty, the front NOx sensor fault diagnosis module is called. X Sensor fault diagnosis module and post-NO X The sensor fault diagnosis module, if it diagnoses NO... X If the sensor malfunctions, an error is reported to the ECU, and the diagnostic process is interrupted. If NO... X If the sensor is fault-free, the urea pump fault diagnosis module is invoked to diagnose nozzle blockage and excessive urea injection faults respectively. If a urea pump fault is diagnosed, an error is reported to the ECU and the diagnosis process is terminated. If the fault location cannot be determined, the sulfur poisoning model is invoked for diagnosis.

[0057] The working process of the sulfur poisoning model of the present invention is as follows: Figure 3As shown, sulfur poisoning includes multiple preset SO2 concentrations ranging from 100ppm to 1000ppm. Input ammonia concentration, original ammonia coverage, etc. Set multiple SO2 concentrations, input them into the sulfur poisoning model, calculate the change in ammonia coverage, return the calculation results to the SCR model, and the SCR model recalculates according to the new ammonia coverage. When the calculation results match the actual situation, sulfur poisoning is judged to have occurred.

[0058] like Figure 4 As shown, specifically, through calculation, if sulfur poisoning occurs, the changes in the active sites on the catalyst surface under the influence of different SO2 concentrations are obtained. The result is used as the ammonia coverage rate change rate, which is multiplied by the initial ammonia coverage rate originally input into the SCR model. This new ammonia coverage rate is then used as the input for the SCR model. The SCR model is called again with the new ammonia coverage rate input. If the change in nitrogen oxide concentration calculated with the new ammonia coverage rate at a certain SO2 concentration matches the actual situation, then sulfur poisoning can be diagnosed. At this time, the actual SO2 concentration is closest to the corresponding preset concentration.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0060] Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A rapid diagnostic system for sulfur poisoning in SCR catalysts, characterized in that, Its application in determining sulfur poisoning in vehicle emission aftertreatment devices (SCRs) includes a sulfur poisoning diagnostic model. This model comprises, in sequence, an SCR model, a front temperature sensor fault diagnosis module, a rear temperature sensor fault diagnosis module, and a front NOx sensor. X Sensor fault diagnosis module, a rear NO X A sensor fault diagnosis module, a urea pump fault diagnosis module, and a sulfur poisoning model; The SCR model includes four reactions: ammonia adsorption catalyst reaction, ammonia desorption catalyst reaction, oxidation reaction, and SCR reaction. The SCR input parameters to the model include tail gas volumetric flow rate, catalyst volume, catalyst outlet temperature, SCR inlet temperature, nitrogen oxide inlet concentration, ammonia inlet concentration, pre-exponential factors and activation energies of the four reactions, initial catalyst ammonia coverage, and ambient temperature. After calculation, the SCR model outputs the ammonia coverage, nitrogen oxide outlet concentration, ammonia outlet concentration, and catalyst outlet temperature after the reaction. The front temperature sensor fault diagnosis module is used to diagnose whether the temperature sensor at the SCR catalyst inlet is malfunctioning based on the calculated actual temperature at the SCR catalyst inlet; the rear temperature sensor fault diagnosis module is used to diagnose whether the temperature sensor at the SCR catalyst outlet is malfunctioning based on the catalyst outlet temperature calculated in the SCR model; the front NO x Sensor fault diagnosis module, used for diagnosing NO upstream of the catalyst X Rapid calculation results of NO concentration at the SCR catalyst inlet. X Diagnose whether the sensor has malfunctioned; the subsequent NO X The sensor fault diagnosis module is used to assess the NOx concentration at the SCR catalyst outlet based on the nitrogen oxide concentration calculated in the SCR model. X Diagnose whether the sensor is malfunctioning; The urea pump fault diagnosis module is used to diagnose whether a fault has occurred during the urea pump injection process, including determining whether the nozzle is blocked based on the urea pump nozzle cross-sectional coefficient k0 and diagnosing whether the urea injection is excessive based on the ammonia coverage rate and the ammonia leakage amount collected downstream. The sulfur poisoning model, based on chemical reaction kinetics calculations, diagnoses sulfur poisoning. It includes three reactions: sulfur dioxide adsorption, reversible sulfur poisoning, and irreversible sulfur poisoning, as well as a set of preset virtual concentrations of sulfur oxides. Parameters input to the model include the start and end times of the call, catalyst volume, SCR temperature, nitrogen oxide inlet concentration, ammonia inlet concentration, initial catalyst ammonia coverage, pre-exponential factors for the three reactions, and activation energies. The model calculates and outputs the rate of change of ammonia coverage on the SCR catalyst surface over a historical period under different virtual SO2 concentrations to simulate the impact of sulfur poisoning on the catalyst at a specific SO2 concentration. The rate of change in ammonia coverage is multiplied by the initial coverage and then output back to the SCR model as a new input parameter. The SCR model uses this new ammonia coverage to predict future NO2 emissions. X Emissions calculation; if NO is at all predetermined SO2 concentrations... X If the predicted emission accuracy does not meet the set threshold, the diagnostic session ends, and engine exhaust monitoring continues; if the predicted SO2 virtual concentration is below the threshold, NO... X If the emission prediction accuracy meets the set threshold, then the NO emission prediction for the future period will continue to be calculated based on this virtual SO2 concentration. X The emissions were compared with the actual situation, and if future NO emissions... X Actual emissions and NO calculated under this virtual SO2 concentration X If the predicted emissions match, then sulfur poisoning is determined to have occurred.

2. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 1, characterized in that, The aforementioned front temperature sensor fault diagnosis module includes a temperature MAP, which is used to quickly calculate the actual temperature at the SCR catalyst inlet and compare the result with the sensor temperature to determine whether the sensor is faulty.

3. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 1, characterized in that, The diagnostic method of the post-temperature sensor fault diagnosis module is to extract the catalyst outlet temperature calculated in the SCR model and compare it with the sensor temperature to determine whether the sensor is faulty.

4. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 1, characterized in that, The preceding NO x Sensor fault diagnosis module, used for NO upstream of catalyst X Establish a MAP between NO concentration and engine operating conditions to monitor NO upstream of the catalyst. X The concentration is quickly calculated, and the result is compared with the sensor concentration to determine whether the sensor is malfunctioning.

5. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 1, characterized in that, The post-NO X The sensor fault diagnosis module diagnoses by extracting the nitrogen oxide concentration calculated from the SCR model and comparing it with the sensor concentration to determine whether the sensor is faulty.

6. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 1, characterized in that, The urea pump fault diagnosis module includes a urea pump nozzle blockage diagnosis unit and a urea injection overload diagnosis unit, each used to diagnose whether the nozzle is blocked and whether the urea injection is excessive.

7. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 6, characterized in that, The urea pump nozzle blockage diagnosis unit is used to calculate the urea pump nozzle section coefficient k0 based on the ammonia concentration at the catalyst inlet and the mass flow rate of the urea solution injection. When k0 is lower than the threshold, the nozzle is diagnosed as blocked.

8. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 6, characterized in that, The urea injection overdose diagnostic unit is used to analyze the combined ammonia coverage rate and the ammonia leakage amount collected downstream. When both exceed the set threshold, it is diagnosed as urea injection overdose.

9. The rapid diagnostic system for sulfur poisoning of SCR catalysts according to claim 1, characterized in that, The concentration of sulfur oxides ranges from 100 ppm to 1000 ppm.

10. A rapid diagnostic method for sulfur poisoning in SCR catalysts, implemented based on the rapid diagnostic system for sulfur poisoning in SCR catalysts according to any one of claims 1-9, characterized in that, During vehicle operation, the ECU constantly monitors NO. X Conversion rate monitoring; when the ECU identifies SCR NO x When the conversion rate drops, record this moment and import data for the next moment. If no anomalies occur within a continuous first preset time period, the call process ends; when more than 75% of the moments in a second preset time period show NO... x If the conversion rate is below 85%, initiate the diagnostic process. Ammonia coverage, NOx concentration, ammonia concentration, and catalyst outlet temperature were calculated using an SCR model. When the catalyst outlet temperature was below 200°C, NO was confirmed to be... X The low conversion rate is caused by temperature, so the diagnostic process is interrupted. If the catalyst outlet temperature is above 200℃, the front and rear temperature sensor fault diagnosis modules are called. If a temperature sensor fault is diagnosed, an error is reported to the ECU and the diagnostic process is interrupted. If the temperature sensor is not faulty, the front NO... X Sensor fault diagnosis module and post-NO X The sensor fault diagnosis module, if it diagnoses NO... X If the sensor malfunctions, an error is reported to the ECU and the diagnostic process is interrupted; if NO... X If the sensor is not faulty, the urea pump fault diagnosis module is invoked to diagnose nozzle blockage and excessive urea injection faults respectively. If a urea pump fault is diagnosed, an error is reported to the ECU and the diagnosis process is terminated. If the fault location cannot be determined, the sulfur poisoning model is invoked for diagnosis. The sulfur poisoning model includes multiple pre-set SO2 concentrations. Calculations are performed to determine the changes in catalyst surface active sites under different SO2 concentrations during sulfur poisoning. This change in ammonia coverage is then used as the ammonia coverage rate, multiplied by the initial ammonia coverage rate, and re-input into the SCR model as the new ammonia coverage rate. The SCR model is then called again to calculate future NO levels. X If the change in nitrogen oxide concentration calculated based on the new ammonia coverage rate at a certain SO2 concentration matches the actual value, then sulfur poisoning is diagnosed. In this case, the actual SO2 concentration is closest to the corresponding preset concentration.

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