• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for determining the NH3 loading of an SCR catalyst in the exhaust system of an internal combustion engine, wherein the NH3 concentration in the exhaust gas is determined downstream of the SCR catalytic converter with at least one sensor, preferably a NOx sensor. In order to improve the accuracy of dynamic models for NH3 level determination of an SCR catalyst, it is envisaged that, based on a measured NH3 concentration after the SCR catalyst, the actual NH3 adsorption and NH3 desorption can be directly determined by the dynamic equilibrium between NH3 adsorption and NH3 desorption. Level of the SCR catalyst is calculated, wherein preferably at least one physical model based on Adsorptionsisothermen is used to determine the dynamic equilibrium.
    公开号:AT510572A4
    申请号:T1998/2010
    申请日:2010-12-01
    公开日:2012-05-15
    发明作者:Bernd Dipl Ing Fh Hollauf；Bernd Dipl Ing Dr Techn Breitschaedel
    申请人:Avl List Gmbh；
    IPC主号:
    专利说明:

    - 1 - 56124
    The invention relates to a method for determining the NH3 loading of an SCR catalytic converter in the exhaust system of an internal combustion engine, wherein the NH3 concentration in the exhaust gas is determined with at least one sensor, preferably a NOx sensor, downstream of the SCR catalytic converter.
    From the publications DE 10 347 130 Al, DE 10 347 131 Al and DE 10 347 132 Al methods for model-based control of an SCR catalytic converter of an internal combustion engine are known, wherein the dynamic model used in each case takes into account the NH3 loading of the SCR catalyst. A modeled NOx value of the dynamic model is continuously adjusted by means of an NOx value measured downstream of the SCR catalyst arranged NOx sensor.
    Dynamic filling level models for SCR control are based on a model of the SCR catalytic converter, which uses mass balances to model the current NH3 load of the catalytic converter. Due to inaccuracies in the sensors and actuators, this modeled NH3 load can drift off the real value during operation. Therefore, at certain intervals, the modeled NH3 load must be balanced with the real load.
    The object of the invention is to improve the accuracy of level models in a simple manner.
    According to the invention this is achieved in that based on a measured NH3 concentration after the SCR catalyst via the dynamic equilibrium between NH3 adsorption and NH3 desorption directly the current NH3 filling level of the SCR catalyst is calculated, preferably for determining of the dynamic equilibrium, at least one physical model based on adsorption isotherms is used. For model matching, first the fill level of the SCR catalyst or the NH3 concentration downstream of the SCR catalyst must be known or metrologically recorded. This can be done in a variety of ways, such as by direct measurement by NH3 sensor or by utilizing the cross sensitivity of conventional NOx sensors to NH3 via a NOx sensor. In the literature, methods are known to reliably detect NH3, such as in overrun mode (see DE 10 20 505 0709 Al).
    O - 2 - - 2 - Θ
    If the NH 3 concentration after the real SCR catalyst is known, the static NH 3 level in the SCR catalyst can subsequently be calculated analytically via an adsorption isotherm.
    Preferably, it is provided that the adsorption isotherms a Lang-muir adsorption isotherm of the form NHJ - is used, where 0, ^, the current NH3 loading, KU is the Adsorptionsgleichgewichtskonstante and CNH3 is the concentration of the component NH3 in the exhaust downstream of the SCR catalyst , the adsorption equilibrium constant KA can be determined from characteristic maps or characteristic curves. If parameters for the reaction kinetics of the adsorption and desorption are known, then the adsorption equilibrium constant KA can also be determined by means of this equation
    K vod • e
    A de, where kad [m / s] is a preexponential term for adsorption and kde [m / s] is a preexponential term for desorption, Ead [J / kmol] is the activation energy for adsorption and ecie [J / kmol] is the activation energy for desorption.
    As an alternative to the Langmuir adsorption isotherm, the adsorption isotherm 0 ^ can also be a BET isotherm of the form Θ =
    K 'ffmax' ^ NHJ 1 + be used, where the current NH3 loading, K of the
    Adsorption coefficient, qmax is the maximum concentration of NH3 in a layer on the surface of the exhaust gas, Csat is the solubility of NH3 and CNh3 is the concentration of the component NH3 in the exhaust gas downstream of the SCR catalyst.
    Furthermore, it is also possible to use a Freundlich isotherm of the form - 3 - k Κ = Κ · Γη WNH3 Λ / lJVW3 as the adsorption isotherm, where the current NH3 loading, Kf the Freundlich coefficient, Cmh3 the concentration of IMH3 in the exhaust gas downstream of the SCR catalyst and n is the Freundlich exponent.
    By the method described can be a quick and accurate comparison of. ·· * ·. NH3 level of the model with the real system (static procedure). This achieves a robust control which can achieve high NOx conversions with low NH3 slip on the SCR catalyst. This makes possible ;·. to significantly improve the accuracy of dynamic level models · *! *. fibers.
    权利要求:
    Claims (5)
    [1]
    Method for determining the NH3 loading of an SCR catalytic converter in the exhaust gas line of an internal combustion engine, wherein the NH3 concentration in the exhaust gas is determined with at least one sensor, preferably a NOx sensor, downstream of the SCR catalytic converter, characterized in that Based on a measured NH3 concentration after the SCR Kataiy-sator on the dynamic equilibrium between NH3 adsorption and NH3 desorption directly the current NH3 level of the SCR catalyst is calculated, preferably for determining the dynamic equilibrium at least one physical model based on adsorption isotherms is used. A method according to claim 1, characterized in that a Langmuir adsorption isotherm of the form 0 Ka'Cnh3 WNII3 - is used as the adsorption isotherm, wherein the current NH3 loading, KA the Adsorptionsgleichgewichtskonstante and CNh3 the concentration of the component NH3 downstream of the SCR catalyst in the exhaust gas is.
    [2]
    3. The method according to claim 2, characterized in that the adsorption equilibrium constant is determined from maps or curves.
    [3]
    4. The method according to claim 2, characterized in that the adsorption equilibrium constant KA with parameters for the reaction kinetics for the adsorption and desorption from l ° L 5. "r. kad [m / s] is a preexponential term for adsorption and kde [m / s] is a preexponential term for desorption, Ead [J / kmol] is the activation energy for adsorption and Ede [J / kmol] is the activation energy for desorption. A method according to claim 1, characterized in that as adsorption isotherm a BET isotherm of the form - 5 - Θ = ^ ΝΗ3 Κ • ql ___ 'C, tnax' NHi (c * Cnhi) 1 + (K-pc, cr NH 3 used where the actual NH3 loading, K is the adsorption coefficient, qmax is the maximum concentration of NH3 in a layer on the surface of the exhaust gas, CMt is the solubility of NH3 and Cnhs is the concentration of the constituent NH3 in the exhaust gas.
    [4]
    6. The method according to claim 1, characterized in that as Adsorptionsisotherme a Freundlich isotherm of the form FD = κ -C n ^ NH3 Λ / 'NHi is used, wherein the current NH3 loading, Kf the Freundlich coefficient, CNH3 the Concentration of NH3 in the exhaust gas downstream of the SCR catalyst and n is the Freundlich exponent.
    [5]
    7. The method according to any one of claims 1 to 6, characterized in that a dynamic NH3 Füllstandsmodei is ausgegiichen with the static NH3 loading.

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    同族专利:
    公开号 | 公开日
    US20130332086A1|2013-12-12|
    WO2012072566A1|2012-06-07|
    AT510572B1|2012-05-15|
    US10408807B2|2019-09-10|
    DE112011103988A5|2013-08-22|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JPH04346819A|1991-05-23|1992-12-02|Niigata Eng Co Ltd|Denitration control device and method|
    DE10347131A1|2002-10-21|2004-05-13|Ford Global Technologies, LLC, Dearborn|exhaust aftertreatment systems|
    DE10347132A1|2002-11-21|2004-06-17|Ford Global Technologies, LLC, Dearborn|exhaust aftertreatment systems|
    DE10347130A1|2002-11-21|2004-06-17|Ford Global Technologies, LLC, Dearborn|exhaust aftertreatment systems|
    DE102005042489A1|2005-09-07|2007-03-08|Robert Bosch Gmbh|Method for operating an internal combustion engine and device for carrying out the method|
    WO2009030346A1|2007-08-28|2009-03-12|Daimler Ag|Operating and diagnostic method for an scr exhaust-gas aftertreatment system|
    WO2009036780A1|2007-09-18|2009-03-26|Fev Motorentechnik Gmbh|Nh3-monitoring of an scr catalytic converter|
    US5656244A|1995-11-02|1997-08-12|Energy And Environmental Research Corporation|System for reducing NOx from mobile source engine exhaust|
    DE102005050709A1|2005-10-22|2007-04-26|Daimlerchrysler Ag|Operating process for exhaust gas treatment system involves detecting output signal of exhaust gas sensor downstream of catalytic converter during operation|
    DE102007009824A1|2006-03-03|2007-09-27|Ford Global Technologies, LLC, Dearborn|System and method for detecting reductant storage|US9181835B2|2013-08-13|2015-11-10|Caterpillar Inc.|Supervisory model predictive selective catalytic reduction control method|
    US9435244B1|2015-04-14|2016-09-06|General Electric Company|System and method for injection control of urea in selective catalyst reduction|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA1998/2010A|AT510572B1|2010-12-01|2010-12-01|METHOD FOR DETERMINING THE NH3 LOADING OF AN SCR CATALYST|ATA1998/2010A| AT510572B1|2010-12-01|2010-12-01|METHOD FOR DETERMINING THE NH3 LOADING OF AN SCR CATALYST|
    US13/991,166| US10408807B2|2010-12-01|2011-11-28|Method for determining the NH3 loading of an SCR catalytic converter|
    PCT/EP2011/071144| WO2012072566A1|2010-12-01|2011-11-28|Method for determining the nh3 loading of an scr catalytic converter|
    DE112011103988T| DE112011103988A5|2010-12-01|2011-11-28|Method for determining the NH3 loading of an SCR catalyst|
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