EP2870334A1 - Procédé d'introduction d'agent de réduction - Google Patents

Procédé d'introduction d'agent de réduction

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Publication number
EP2870334A1
EP2870334A1 EP13732423.2A EP13732423A EP2870334A1 EP 2870334 A1 EP2870334 A1 EP 2870334A1 EP 13732423 A EP13732423 A EP 13732423A EP 2870334 A1 EP2870334 A1 EP 2870334A1
Authority
EP
European Patent Office
Prior art keywords
reducing agent
exhaust gas
conversion rate
dosing strategy
deviation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13732423.2A
Other languages
German (de)
English (en)
Inventor
Peter Bauer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Continental Automotive GmbH
Original Assignee
Emitec Gesellschaft fuer Emissionstechnologie mbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Emitec Gesellschaft fuer Emissionstechnologie mbH filed Critical Emitec Gesellschaft fuer Emissionstechnologie mbH
Publication of EP2870334A1 publication Critical patent/EP2870334A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2370/00—Selection of materials for exhaust purification
    • F01N2370/02—Selection of materials for exhaust purification used in catalytic reactors
    • F01N2370/04—Zeolitic material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/05—Systems for adding substances into exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/026—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting NOx
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1406—Storage means for substances, e.g. tanks or reservoirs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0418—Methods of control or diagnosing using integration or an accumulated value within an elapsed period
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1402—Exhaust gas composition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1621—Catalyst conversion efficiency
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1622—Catalyst reducing agent absorption capacity or consumption amount
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the invention relates to a method for supplying reducing agent into an exhaust gas mass flow in an exhaust gas treatment device, in particular for mobile internal combustion engines.
  • SCR selective catalytic reduction
  • an SCR catalyst is used, which has a coating which allows the reaction at relatively low temperatures.
  • selective catalytic reduction nitric oxide compounds are reacted with ammonia to form nitrogen and water.
  • ammonia is desirable to provide as much ammonia as possible for the reaction.
  • the stoichiometric addition of ammonia therefore represents the desired amount added.
  • ammonia to the effluent exhaust gas in the respectively required amount is a task that could not be achieved before or despite very large regulatory effort only very inaccurate. Therefore, storage catalysts are often used, store the excessively added ammonia, ie store, and provide in a negative dosage of ammonia in turn stored ammonia for the reaction with the exhaust gas. So also a very frequent operation of the addition system (injectors, pumps, etc.) should be prevented so that the lowest possible wear and energy consumption can be achieved there.
  • a disadvantage of a storage catalytic converter is that the storage of ammonia in a storage catalytic converter is subject to a large number of boundary conditions which influence the maximum storage quantity, that is to say the degree of filling, of the storage catalytic converter.
  • the maximum loading is subject to a strong temperature dependence and aging, especially due to thermally induced changes in the storage coating.
  • the measuring sensors are also subject to various disturbance variables for controlling the loading of the storage catalytic converter. Overall, this can lead to erroneous operations of the scheme, which reduce the utilization of the storage catalytic converter or even impossible.
  • the present invention has the object, at least partially overcome the disadvantages and problems known from the prior art.
  • the object is solved by the features of the independent claims.
  • Advantageous developments are the subject of the dependent claims.
  • the invention relates to a method for supplying reducing agent into an exhaust gas mass flow in an exhaust gas treatment apparatus, which includes a reductant supply point, a reductant storage catalyst and an SCR catalyst for performing selective catalytic reduction of nitrogen oxide compounds in the exhaust gas, comprising at least the following Steps:
  • the reducing agent to be supplied may be in the form of gaseous ammonia and / or a reducing agent precursor, e.g. As a urea-water solution, the exhaust gas mass flow are added in the exhaust treatment device. This is either added directly to the exhaust gas and thermally converted into ammonia and water (thermolysis) and / or first (exhausts external and / or exhaust gas internally) in a hydrolysis catalyst to ammonia processed (hydrolysis).
  • a reducing agent is often known under the trade name AdBlue® urea-water solution with 32.5% urea used.
  • the reducing agent is usually added to the Abas with a metering nozzle, a valve or an injector, with a good mixing of the exhaust gas with the reducing agent, for example, is supported by a mixer. This ensures that the two reactants - nitrogen oxide compound and ammonia - in the exhaust treatment device can come into contact and react.
  • This supply of reducing agent is made via the supply point provided in the exhaust gas treatment device.
  • the exhaust treatment device is connected via an exhaust pipe to an internal combustion engine.
  • the internal combustion engine is in particular a diesel internal combustion engine.
  • a storage catalyst is provided, which is provided for the storage of reducing agent or exclusively ammonia.
  • the storage catalyst on a corresponding coating, for.
  • a coating with iron zeolite or with copper zeolite typically require a storage capacity of about 1 gram of ammonia per liter.
  • This storage capacity is usually limited to a relatively narrow temperature range, for. B. between 100 and 400 ° C, with respect to the temperature limits in each case the storage capacity rapidly decreasing.
  • the exact temperature limits and the exact dependency of the storage capacity on the temperature depend on the respective coating.
  • an SCR catalyst is provided in the exhaust treatment device.
  • the storage catalyst and the SCR catalyst can also be realized in a catalyst carrier body. This catalyst carrier body then preferably has a coating which has a storage capacity and can also catalyze an SCR reaction.
  • the selective catalytic reduction of Stickstoffoxidverbmditch is made possible by means of the reducing agent at low temperatures, for. B. already from 130 ° C to 150 ° C.
  • the uptake of ammonia in the SCR catalyst starts (depending on the type of coating) a little earlier.
  • a first metering strategy is carried out, after which the target conversion rate of nitrogen oxide compounds in the SCR catalyst is to be achieved.
  • the target conversion rate is a parameter that indicates how strong the reaction of nitrogen oxides compounds in the exhaust gas should be theoretical under the present operating conditions of the internal combustion engine and exhaust gas treatment device.
  • the existing load in the storage catalytic converter is determined.
  • the loading refers to the absolute amount of available reductant which is incorporated into the storage catalyst by the coating and is available for reaction with passed exhaust gas or nitrogen oxide compounds, respectively.
  • the maximum absorption capacity of the storage catalyst is known and, taking into account the addition of reducing agent and / or the ambient conditions, it is possible to determine to what proportion this maximum absorption capacity is currently obtained. is enough.
  • the absolute amount of available reducing agent can be determined.
  • a (still) possible or unused storage capacity is detected in the storage catalytic converter.
  • the storage capacity of the storage catalyst is, as already mentioned, dependent on the present temperature. Is z. For example, if the temperature is too low or too high, the storage capacity will decrease rapidly. Furthermore, the storage capacity is also subject to an aging of the storage catalyst and / or a possible poisoning of the storage material by z. As sulfur in the fuels and consequently a sulfate formation, which reduces the storage of ammonia or even (partially) prevented. The storage capacity typically decreases with increasing aging.
  • the capacity and the storage capacity can be model-based z. B. via a look-up table (a map) are determined. However, they can also be detected by direct measurements of the added amount and the actual conversion rate or the slip, that is, the passage through the SCR catalyst due to a superstoichiometric amount of reducing agent.
  • the target conversion rate of nitrogen oxide compounds in the SCR catalyst is determined model-based. Taking into account various measured values, such. As the temperature of the SCR catalyst, the storage catalyst, the nitrogen oxide compounds in the current exhaust gas and the like, which in a model that simulates the actual processes under the given conditions control technology, the target conversion rate is preferably determined. In this case, empirical data and / or functions can be used. Furthermore, based on the model, the fill quantity and / or the storage capacity of the storage catalytic converter, but also the current operating state of the internal combustion engine and / or a predicted operating state can be included in order to determine the model-based target conversion rate. To achieve the target conversion rate, the addition of reductant, that is, the reductant feed rate, is adjusted accordingly.
  • reductant that is, the reductant feed rate
  • the result of the first dosing strategy is achieved by monitoring the current turnover rate.
  • the current turnover rate is determined by a nitrogen oxide sensor, so that a deviation from the target conversion rate can be detected.
  • the controller set up to execute the method a deviation between the current turnover rate and the set target conversion rate is registered.
  • step e) is not carried out until, in step d), a deviation is registered over a period which is longer than a predetermined maximum duration.
  • the method it is not immediately switched to a different dosing strategy when the first limit value is exceeded, but only when this occurs over a predetermined period of a maximum duration.
  • a sudden control behavior is prevented, which could be triggered due to normal irregularities and / or measurement errors.
  • the first limit value can be set very close to the target conversion rate. This means that even a small deviation can lead to the triggering of a dosing strategy change. In doing so, a very exact adherence to the target implementation rate can be achieved; because if the first limit value is exceeded over a longer period than the predetermined maximum duration, it can be safely assumed that the first dosing strategy is currently based on a faulty model or leads to erroneous results.
  • the method may be arranged such that a means for detecting the period is reset again as soon as a deviation no longer occurs, and is restarted only at the first recurrence of a deviation.
  • the conversion rate can correspond to the target conversion rate and / or (smaller) deviations can occur do not exceed the first limit.
  • the means for detecting the period is preferably reset. After the change, it is initially assumed that a suitable metering of reducing agent can now be carried out with the further metering strategy.
  • step e) the further dosing strategy is carried out for a predetermined time period which is longer than the predetermined maximum duration, and then the first dosing strategy according to step a) is changed back.
  • the second metering strategy must be carried out after emptying and / or during the heating of the storage catalytic converter, as if no storage catalytic converter gate is present and an implementation at high exhaust gas temperatures is present. Furthermore, such an embodiment of the method makes it possible that no unnecessarily rapid change takes place between the metering strategies, whereby the systems are spared. In addition, this reduces the amount of ammonia present in the store (unknown). This amount of ammonia can cause a slip so that ammonia exits the exhaust system.
  • a filling model is used to determine the loading of the storage catalyst, which is reset after the predetermined period.
  • the filling model provides the basis for the addition of reducing agent in the first dosing strategy. Now, if the desired degree of filling and the maximum degree of filling to different, that is, the maximum degree of filling drops below the usual storage capacity of the storage catalyst in normal conditions, so for example, there is an offset in the filling model. So if the filling model is reset, it is possible to make this offset usable again for the implementation. In particular, after a successful detoxification strategy, the storage capacity of the storage catalyst is increased, so that a reset of the filling model for a better utilization of the load is possible.
  • the filling model is adapted again to the actual conditions of the storage catalytic converter via the regulation and is not restricted by measured values before the further dosing strategy.
  • a reduced second target conversion rate is set in the further dosing strategy.
  • the further dosing strategy is otherwise carried out like the first dosing strategy. Due to the reduced second target conversion rate compared to the first target conversion rate, the amount of added reducing agent, ie the reductant agent supply rate, reduced.
  • the filling quantity or the charge is reduced or the storage catalytic converter is emptied. At least, however, the storage catalytic converter is no longer filled up if a corresponding amount of nitrogen oxide compounds in the exhaust gas is correctly determined and / or the reducing agent supply rate is adjusted despite incorrectly determined values.
  • the first target conversion rate may require a reduction in nitrogen oxide emissions between 60 percent and 100 percent.
  • the second target conversion rate may be lower by a factor of 0.5 to 0.95 in order to safely avoid actual malfunctions of the exhaust system and / or control-technical error messages.
  • a static proportional controller (35) is used for carrying out the dosing strategy (1) in step a) if an operating state of the exhaust gas treatment device (23) is present and a dynamic proportional-integral controller (37) is used is when there is a dynamic operating state of the internal combustion engine, wherein in step d) in addition to the deviation, a comparison between a first control value of the static proportional-integral controller and a second control value of the dynamic proportional-integral controller is performed and taken into account.
  • the dosing strategy (1) is meant the determination of the reducing agent rate to be supplied in accordance with the target conversion rate from step a) in step b).
  • the first control value and the second control value respectively correspond to a reducing agent rate to be supplied which is determined or determined by a controller as a function of the target conversion rate from step a).
  • a static operating state of an exhaust gas treatment device is characterized by no or only slowly changing operating parameters of the exhaust gas treatment device and occurs, for example, when a connected to the exhaust gas treatment device internal combustion engine is operated with constant load and speed.
  • a dynamic operating state of a Gas treatment device is characterized by rapidly changing operating parameters of the exhaust treatment device and occurs in particular with frequent and rapid load and speed changes of the internal combustion engine. Whether there is a dynamic or a static operating state can be detected, for example, on the basis of the gradient of an operating parameter of the exhaust gas treatment device. If the gradient of a certain operating parameter exceeds a predetermined limit, there is a dynamic operating condition. Otherwise there is a static operating state.
  • the static proportional-integral controller may be suitable for setting a dosing amount particularly precisely.
  • the dynamic proportional integral controller is less susceptible to errors in terms of changing operating conditions in the exhaust treatment device.
  • control unit which is set up to carry out the described method is set up to produce a first control value by means of a static proportional-integral controller (PI controller) and a second control value by means of a dynamic program.
  • PI controller proportional integral controller
  • the PI controller combines the properties of P-controller and I-controller.
  • the P component immediately achieves a control deviation proportional to the control deviation in the path.
  • the I component has the effect that previous control variables are taken into account and thus an excessive response to a singularly occurring deviation is mitigated.
  • the PI controller is suitable for bringing the control variable to the reference variable quickly and without permanent deviation.
  • the static proportional-integral controller is set up in such a way that the stored value for the integral component of the controller remains unchanged, and preferably zugt the input quantities remain constant.
  • the dynamic proportional-integral controller can receive different input variables, but in particular only the integrating component (including the memory component) is reset under certain conditions.
  • the conditions for resetting the integrating portion may be e.g. B. the change of a dosing.
  • the proportional-integral controller adapts to the current input values without exerting a calibration based on the previously achieved control values, as described above.
  • the static proportional-integral controller retains its memory and processes the past input variables in the current calculation of the control value, while the just-reset dynamic proportional-integral controller alone responds to the current value.
  • the dynamic proportional-integral controller is z. B. set to respond only within a dosing strategy attenuating to the current input variables and to incorporate no damping effect from the previous dosing with.
  • the deviation is compared with a plurality of limit values, the further dosing strategy being selected on the basis of the limit values according to the following scheme:
  • Deviation greater than the first limit value and less than a second limit value a second metering strategy is executed
  • Deviation greater than the second limit and less than a third limit a third dosing strategy is executed
  • Deviation greater than the third limit a fourth dosing strategy is executed.
  • successive dosing strategies first, second, third, fourth dosing strategies
  • various specifications can be carried out, so that the exhaust gas treatment device is returned to a state in which a first target conversion rate can be achieved again.
  • z. B the temperature of the exhaust gas are raised in order to detoxify the storage catalyst, the storage catalyst are emptied, and / or other measures are taken to increase the functionality of the storage catalytic converter or the SCR catalyst again.
  • a dosing strategy may also include setting the target conversion rate so that a storage catalyst is not needed. Thus, a sufficiently accurate control can be achieved, even if the storage catalytic converter is no longer sufficiently functional.
  • the dosing strategies can be staggered or specified in the order to be initiated.
  • a first dosing strategy is executed when there is an optimal implementation for a fully functional system (basic strategy).
  • a second metering strategy is carried out if an adaptation of the charge by emptying the storage catalytic converter is to be achieved (charge reduction strategy or offset correction strategy), ie a reduced reducing agent feed rate is set.
  • a third dosing strategy may be for a reduced implementation in emptying and detoxification by burning off sulphates (detoxification strategy).
  • a fourth metering strategy can be set up for a permanent operation without a storage catalytic converter (emergency strategy), because the storage catalytic converter no longer works (sufficiently) and / or does not react to the regeneration efforts. But there are also other orders and strategies possible.
  • the integrating control component of a PI controller for performing one of the dosing strategies is reset during a change in the dosing strategy.
  • the integrating control component of a PI controller allows a long-term and accurate adaptation of the Dosing quantity to the present operating conditions. Due to the integrating control component, such a successful adaptation becomes possible when there is a static operating state of the exhaust gas treatment device. If a dynamic operating state of the exhaust treatment device is present, such an adjustment is usually not possible because the integrating controller can not react quickly enough with short-term changes in operating parameters. Therefore, it is advantageous to reset the integrating control component in a dynamic operating state.
  • a change in the metering strategy strongly indicates in the described method that there is a dynamic operating state. Normally, the deviation between the present conversion rate and the target conversion rate, which is determined in step d) of the method, is accompanied by a dynamic operating state. It is therefore advantageous to reset the integrating control component when changing the dosing strategy.
  • the power output is proportional to the generation of nitrogen oxide compounds. Determining an absolute target value based on the power output achieves particularly accurate target value acquisition without the need for direct measured values.
  • An absolute target value for the mass flow of nitrogen oxide compounds is based, for example, on the emission standards required by law.
  • An exhaust gas standard for example, represents the upper limit of the permissible mass of nitrogen oxide compounds in the purified exhaust gas.
  • the setting of a target percentage reduction of nitrogen oxide compounds is particularly oriented to the ability to react nitrogen oxide compounds in the exhaust gas purification process and therefore particularly reliable.
  • a third conversion rate specification that provides a ratio of an amount of nitrogen oxide compounds upstream of the SCR catalyst and an amount of nitrogen oxide compounds downstream of the SCR catalyst.
  • a conversion rate specification is a calculated value that indicates how high the proportion of the nitrogen oxide compounds reacted in the SCR catalyst should be on the total nitrogen oxide compounds present in the unpurified exhaust gas.
  • the one which gives the lowest conversion of nitric oxide compounds is selected.
  • this conversion rate default, it is achieved that, with a high probability, the target conversion rate can be achieved and at the same time slip safely avoided.
  • the metered amount is reduced until there is no charge in the storage catalytic converter and then the starting time is determined. The process is therefore started with an empty storage catalyst. By determining the start time, when there is no more loading, it is possible to avoid that model-specific calculation errors lead to a wrong sequence of a dosing strategy.
  • the method steps a) to e) are carried out regularly in the manner of a loop repeatedly.
  • a motor vehicle having an internal combustion engine and an exhaust treatment apparatus for purifying the exhaust gases of the internal combustion engine, which includes a reductant supply site, a reductant storage catalyst, and an SCR catalyst for performing a selective catalytic reduction Of nitrogen oxides in the exhaust gas, and a control device that is designed and set up to carry out a method described herein.
  • a stationary plant which has an internal combustion engine and an exhaust gas treatment device for cleaning the exhaust gases of the internal combustion engine, which has a supply point for the reducing agent, a storage catalyst for the storage of reducing agent and an SCR catalyst for performing a has selective catalytic reduction of nitrogen oxide compounds in the exhaust gas, and a control unit that is designed and set up to carry out a method described herein.
  • a stationary plant may be, for example, a power generator.
  • FIG. 4 shows an arrangement of an exhaust gas treatment device in a motor vehicle.
  • the first dosing strategy 1, the second dosing strategy 2 and the third dosing strategy 3 are shown centrally, which each have a first target conversion rate 4 and a first threshold 14, a second target conversion rate 5 and a second threshold 15 and a third target conversion rate 6 and a third threshold 16 generate.
  • a switching operator 7 decides, based on the control signal 20 from the decision operator 11, which target conversion rate and which limit value (in this example, the first conversion rate 4 and the first limit value 14) are used.
  • the switching operator 7 can also be connected upstream of the metering strategies, so that only one of the metering strategies is carried out in order to save computing capacity.
  • the controller 8 calculates a reduction telzubowrate 9, which leads in the SCR catalytic converter 25 to a current turnover rate 10.
  • the current turnover rate 10 is compared with the selected target conversion rate (here: the first target conversion rate 4) by a subtraction operator 12. This results in a deviation 13 which is compared with the selected limit value (here: the first limit value 14) in the comparison operator 17. If the deviation 13 exceeds the limit 14, an entry is made in the memory operator 18.
  • the memory operator 18 is e.g. B. executed as a counter.
  • the reducing agent feed rate 9 represents an input variable for each of the metering strategies 1 to 3. Furthermore, various input variables in different numbers are shown purely schematically at the respective metering strategies.
  • a reset signal 22 for the integrating portion 21 of the controller 8 is possible at the decision operator 11, which z. B. is reset when changing the dosing.
  • the predetermined maximum duration 19 is reset if the decision operator 11 is to be activated.
  • FIG. 2 shows an alternative controller 8, which comprises a static proportional integral controller 35 and a dynamic proportional-integral controller 37.
  • the static proportional-integral controller 35 outputs a first control value 36
  • the dynamic proportional-integral controller 37 outputs a second control value 38.
  • the first control value 36 and the second control value 38 each correspond to a proposal for a reducing agent feed rate.
  • the first control value 36 or the second control value 38 is selected by the selection processor 39 and used as the reducing agent feed rate 9.
  • This controller 8 is alternatively used in the circuit diagram of FIG. 1 accordingly.
  • FIG. 3 shows a first dosing strategy 1, in which a level adjustment can be carried out.
  • FIG. 3 is a detailed representation of the first dosing strategy 1, as also shown and used according to FIG. 1 (top left).
  • FIG. 4 shows a motor vehicle 34 in which an internal combustion engine 24 is connected to an exhaust gas treatment device 23. In the exhaust treatment device 23 are in the flow direction 32 z. B. a Oxidati- onskatalysator 31 and a subsequent SCR catalyst 25 is arranged.
  • a storage catalytic converter 26 which can store reducing agent, which can be stored via the supply point 27, which is connected to a reducing agent accumulator 33.
  • Values for the respective dosing strategies are determined via a first sensor 29 and a second sensor 30. These represent input variables for the control unit 28, which controls a reducing agent feed rate 9 for the feed point 27 according to a described method.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

Procédé d'introduction d'agent de réduction dans un flux massique de gaz d'échappement dans un dispositif de traitement des gaz d'échappement (23) qui comporte un site d'introduction (27) pour l'agent de réduction, un catalyseur accumulateur (26) pour le stockage d'agent de réduction et un catalyseur SCR (25) destiné à opérer une réduction catalytique sélective de composés d'oxyde d'azote dans les gaz d'échappement. Selon ledit procédé, à l'étape a) une première stratégie de dosage (1) est appliquée, le chargement du catalyseur accumulateur (26) en agent de réduction étant surveillé et un premier taux de conversion cible (4) étant déterminé sur la base du chargement effectué. À l'étape b), de l'agent de réduction est introduit selon le premier taux de conversion cible (4). À l'étape c), un taux de conversion (10) effectif obtenu avec le catalyseur SCR (25) est déterminé. Ensuite, à l'étape d) le taux de conversion effectif (10) est comparé au premier taux de conversion cible (4) et un écart (13) est enregistré. Enfin, à l'étape e), une nouvelle stratégie de dosage (2, 3) est appliquée lorsque l'écart (13) dépasse une première valeur limite (14), le chargement du catalyseur accumulateur (26) n'étant pas pris en compte lors de l'application de la nouvelle stratégie de dosage (2, 3).
EP13732423.2A 2012-07-04 2013-06-20 Procédé d'introduction d'agent de réduction Withdrawn EP2870334A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE201210105954 DE102012105954A1 (de) 2012-07-04 2012-07-04 Verfahren zur Zufuhr von Reduktionsmittel
PCT/EP2013/062879 WO2014005851A1 (fr) 2012-07-04 2013-06-20 Procédé d'introduction d'agent de réduction

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EP2870334A1 true EP2870334A1 (fr) 2015-05-13

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US (1) US9598996B2 (fr)
EP (1) EP2870334A1 (fr)
JP (1) JP2015522749A (fr)
KR (1) KR101719931B1 (fr)
CN (1) CN104428504A (fr)
DE (1) DE102012105954A1 (fr)
WO (1) WO2014005851A1 (fr)

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SE540746C2 (en) * 2015-10-28 2018-10-30 Scania Cv Ab Method and system for use when correcting supply of an additive to an exhaust gas stream

Family Cites Families (13)

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Publication number Priority date Publication date Assignee Title
JPH0263524A (ja) * 1988-08-30 1990-03-02 Sumitomo Metal Ind Ltd 排ガス脱硝装置のｎｈ↓３注入量の制御方法
JP3979153B2 (ja) * 2002-04-03 2007-09-19 三菱ふそうトラック・バス株式会社 内燃機関のＮＯｘ浄化装置
DE102007040439A1 (de) 2007-08-28 2009-03-05 Daimler Ag Betriebs- und Diagnoseverfahren für ein SCR-Abgasnachbehandlungssystem
CN102016250B (zh) * 2008-04-30 2013-05-01 康明斯知识产权公司 用于还原scr催化器上的nox排放物的装置、系统和方法
US8074445B2 (en) 2008-04-30 2011-12-13 Cummins Ip, Inc. Apparatus, system, and method for reducing NOx emissions on an SCR catalyst
DE102008036885A1 (de) * 2008-08-07 2010-02-11 Daimler Ag Verfahren zum Betreiben einer Abgasreinigungsanlage mit einem SCR-Katalysator
CN101818679A (zh) * 2010-02-09 2010-09-01 苏州派格力减排系统有限公司 车用scr系统闭环控制系统及相关控制方法
US8991154B2 (en) * 2010-07-12 2015-03-31 Mack Trucks, Inc. Methods and systems for controlling reductant levels in an SCR catalyst
DE102010034707A1 (de) * 2010-08-18 2012-02-23 Emitec Gesellschaft Für Emissionstechnologie Mbh Verfahren zum Betrieb einer Abgasbehandlungsvorrichtung
WO2012022687A1 (fr) * 2010-08-18 2012-02-23 Emitec Gesellschaft Für Emissionstechnologie Mbh Procédé pour faire fonctionner un dispositif de traitement de gaz d'échappement
DE102010049070A1 (de) * 2010-10-20 2012-04-26 Emitec Gesellschaft Für Emissionstechnologie Mbh Verfahren zum Betrieb einer Abgasbehandlungsvorrichtung
DE102011011441B3 (de) 2011-02-16 2012-06-14 Mtu Friedrichshafen Gmbh Verfahren zur dynamischen Durchbrucherkennung für SCR-Katalysatoren
DE102011011411B4 (de) * 2011-02-16 2018-08-23 Servatius Schneiders System und Verfahren zur Kultivierung und Ernte von Pilzen

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JP2015522749A (ja) 2015-08-06
DE102012105954A1 (de) 2014-01-09
KR20150029014A (ko) 2015-03-17
US20150113958A1 (en) 2015-04-30
WO2014005851A1 (fr) 2014-01-09
US9598996B2 (en) 2017-03-21
CN104428504A (zh) 2015-03-18
KR101719931B1 (ko) 2017-03-24

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