CN101592060B - Exhaust gas after-treatment device and method for operating the same - Google Patents

Exhaust gas after-treatment device and method for operating the same Download PDF

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Publication number
CN101592060B
CN101592060B CN2009101465240A CN200910146524A CN101592060B CN 101592060 B CN101592060 B CN 101592060B CN 2009101465240 A CN2009101465240 A CN 2009101465240A CN 200910146524 A CN200910146524 A CN 200910146524A CN 101592060 B CN101592060 B CN 101592060B
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catalytic converter
storage catalytic
load
exhaust gas
storage
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CN101592060A (en
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亚西尔·雅各布
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Ford Global Technologies LLC
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Ford Global Technologies LLC
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    • 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
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
    • 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
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • 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]
    • 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
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • 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
    • 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
    • Y02T10/40—Engine management systems

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

Abstract

The present invention relates to an exhaust gas after-treatment device and a method for operating the same. The exhaust gas after-treatment device is provided with a NOx storage catalytic converter (10) and an SCR catalytic converter (20). The NOx storage catalytic converter (10) is used for storing the nitrogen oxide in the exhaust gas (5) supplied from an internal combustion engine. The SCR catalytic converter (20) is equipped to the downstream of the NOx storage catalytic converter (10) for selectively catalytically reducing the nitrogen oxide in the exhaust gas (5) supplied to the SCR catalytic converter (20). The state variable value which depends on the state characteristic of the exhaust gas after-treatment device triggers at least one regeneration stage used for regenerating the NOx storage catalytic converter (10), wherein the selection of the state variable used for triggering the standard of the regeneration stage depends on the aging state of the NOx storage catalytic converter (10). The exhaust gas after-treatment device and the method of the invention can realize high-efficiency regeneration of NOx storage catalytic converter.

Description

The method of exhaust gas post-treatment device and operation exhaust gas post-treatment device
Technical field
The present invention relates to the method for exhaust gas post-treatment device and operation exhaust gas post-treatment device.
Background technique
The method according to this invention is used in the exhaust gas post-treatment device, and this exhaust gas post-treatment device has NO xThe storage catalytic converter (is also referred to as the nitrogen oxide trap for rare air-fuel ratio operation, or is called for short i.e. " the rare NO of LNT xCatcher) and the SCR catalytic converter, this SCR catalytic converter stands to use the operational phase of dense air fuel ratio termly, in order to impel NO xThe regeneration of storage catalytic converter.
NO xNitrogen oxide (the NO that the storage catalytic converter absorbs and storage is emitted in the stage in rare air-fuel ratio operation by explosive motor x).In case NO xThe NO of storage catalytic converter xMolecule is saturated, just needs to use the operational phase (dense air-fuel ratio operation continues several seconds usually) of dense air fuel ratio to clean described NO xThe storage catalytic converter.At this moment, allow the NO of storage xThe release of molecule and minimizing form the composition of pollution-free load (non-contaminant-laden), and this composition is mainly nitrogen, carbon dioxide and water vapour.The frequency of described cleaning course is by NO xDischarging degree and NO xThe storage capacity of storage catalytic converter is definite, and wherein storage capacity depends on delivery temperature.
In addition, NO xThe storage catalytic converter also is stored in the sulphate that comprises in the exhaust of emitting, and sulphate can cause NO xDeteriorated and the NO of storage catalytic converter xThe reduction of storage capacity.For reducing NO xThe sulphate of storing in the storage catalytic converter namely triggers sweetening process, NO xThe storage catalytic converter must be heated to and be generally 600 ℃ to 700 ℃ high temperature, and the supply reducing gas, and explosive motor operates the regular period in dense air-fuel ratio operation pattern for this reason.This can cause NO xThe serious Heat Ageing of storage catalytic converter, as a result NO xThe transformation efficiency of storage catalytic converter significantly reduces until the end in its working life.
In the dense air-fuel ratio operation stage, also may produce ammonia (NH 3).The amount of the ammonia that produces depends primarily on air fuel ratio, the NO in the exhaust xNO in the storage catalytic converter xLoad, NO xThe temperature of storage catalytic converter, exhaust quality flow rate and NO xThe degree of aging of storage catalytic converter.Along with NO xThe storage catalytic converter is progressively aging and because the sulphate of accumulation because heat is deteriorated, NO xThe ability of the nitrogen oxide of the storage capacity of storage catalytic converter and conversion storage thereof is subject to significantly adverse effect.This causes ammonia (NH inevitably 3) formation, particularly in dense air fuel ratio operating mode, ammonia (NH 3) formation can be owing to from NO xNitrogen oxide and NO that the storage catalytic converter discharges xNitrogen oxide in the exhaust stream of the ingress of storage catalytic converter.
For stoping NH 3From the tailpipe discharging, at NO xThe downstream of storage catalytic converter arranges SCR catalytic converter (being the catalytic converter of selective catalytic reduction).Described SCR catalytic converter operates with passive mode, by storing NO in dense air fuel ratio in the stage xThe ammonia that the storage catalytic converter produces.Because at NO xThe NO that escapes on the downstream direction of storage catalytic converter xEffulent reduces, and then the ammonia of storage consumes in the stage more slowly in rare air-fuel ratio operation.
EP 1 435 437 A1 for example are disclosed in the NO that is used for that uses in lean mixture (lean-mix) motor xThe device of exhaust aftertreatment, wherein NO xThe storage catalytic converter can be combined with in order to use at NO with the SCR catalytic converter xAmmonia (the NH that produces in the storage catalytic converter 3), to pass through NO at exhaust stream xReduce the nitrogen oxide that keeps in the exhaust stream after the storage catalytic converter.
NO xNO is depended in the triggering of the regenerative process of storage catalytic converter usually xThe NO of storage catalytic converter xLoad condition occurs, and wherein in dense air-fuel ratio operation in the stage, the SCR catalytic converter of passive operation is stored in NO xThe ammonia that produces in the storage catalytic converter also consumes described ammonia.
Summary of the invention
An object of the present invention is to provide the method for exhaust gas post-treatment device and operation exhaust gas post-treatment device, this exhaust gas post-treatment device has NO xStorage catalytic converter and SCR catalytic converter, this allows NO xThe more high efficiency regeneration of storage catalytic converter.
Realize above-mentioned purpose by a kind of method and exhaust gas post-treatment device that operates exhaust gas post-treatment device.
In the method that is used for the operation exhaust gas post-treatment device according to the present invention, this exhaust gas post-treatment device has NO xStorage catalytic converter and SCR catalytic converter, NO xThe storage catalytic converter is used for storage from the nitrogen oxide of the exhaust of explosive motor supply, and the SCR catalytic converter is arranged on NO xThe downstream of storage catalytic converter is used for the nitrogen oxide that catalytic reduction optionally is fed to the exhaust of this SCR catalytic converter.Depend on the state variable value as the status flag of exhaust gas post-treatment device, trigger for regeneration NO xAt least one regeneration stage of storage catalytic converter.
The method is characterized in that and depend on NO xThe ageing state of storage catalytic converter selects consideration to be used for the state variable of the standard in triggering regeneration stage.
According to the present invention, provide a kind of consideration NO xThe strategy of execution of the cleaning course of dense empty burning mixt is used in the ageing state optimization of storage catalytic converter.
In the method for routine, depend on the NO that uses dense empty burning mixt xThe NO of storage catalytic converter xThe triggering of load condition generation cleaning course, and at new not aged NO xThe SCR catalytic converter of passive operation in the situation of storage catalytic converter is (at dense air-fuel ratio operation SCR catalytic converter storage NO in the stage xThe ammonia that produces in the storage catalytic converter also consumes described ammonia) suitably represent the best approach, because in this case, whole conversion of nitrogen oxides is mainly by NO xThe storage of storage catalytic converter and transformation efficiency are determined.
Yet described method is at aging NO xNo longer be best in the situation of storage catalytic converter, about the NO to integral body xThe main contributions that transforms occurs from NO xThe storage catalytic converter is to the conversion of SCR catalytic converter, simultaneously NO xThen the function of storage catalytic converter basically reduces to and produces ammonia (NH 3) for the SCR catalytic converter.
NO is depended in the timing that the present invention is based on the cleaning course of implementing the dense empty burning mixt of use xThe design of the ageing state of storage catalytic converter.More accurately, has relatively new not aged NO xIn the device of storage catalytic converter, depend primarily on NO xThe NO of storage catalytic converter xLoad the triggering (being their beginning and end) of cleaning or regeneration occurs, and along with NO xThe enabling and stopping using of cleaning course of dense empty burning mixt used in the aging increase of storage catalytic converter, the ammonia load control that depends primarily on the SCR catalytic converter.
According to a preferred embodiment, also consider NO xThe ageing state of storage catalytic converter carries out at NO xThe control of the air fuel ratio of the exhaust mixture of the ingress of storage catalytic converter (λ value).More accurately, has relatively new not aged NO xIn the device of storage catalytic converter, described control is associated with NO xThe NO of the optimization in the storage catalytic converter xTransform, and have aging NO xIn the device of storage catalytic converter, described control is associated with NO xThe NH of the optimization in the storage catalytic converter 3Produce.
For NO xThe NO of the optimization in the storage catalytic converter xTransform, particularly might in from 0.90 to 1.0 scope, set the λ nominal value.For NO xThe ammonia of the optimization in the storage catalytic converter produces, and particularly might set the λ nominal value in 0.80 to 0.90 scope.
The invention still further relates to and have NO xThe exhaust gas post-treatment device of storage catalytic converter and SCR catalytic converter, NO xThe storage catalytic converter is used for storage from the nitrogen oxide of the exhaust of explosive motor supply, and the SCR catalytic converter is arranged on NO xThe downstream of storage catalytic converter is used for the nitrogen oxide that catalytic reduction optionally is fed to the exhaust of SCR catalytic converter, and wherein this exhaust gas post-treatment device also comprises for definite NO xThe NO of storage catalytic converter xThe device of load, be used for to determine the NH of SCR catalytic converter 3The device of load, and be used for to trigger NO xThe equipment in the regeneration stage of storage catalytic converter.This device is characterised in that for triggering NO xThe device design in the regeneration stage of storage catalytic converter is for depending on NO xThe ageing state of storage catalytic converter is based on NO xThe NO of storage catalytic converter xLoad or based on the NH of SCR catalytic converter 3The load triggers regeneration stage.
About advantage and the preferred embodiment of exhaust gas post-treatment device, in conjunction with the method according to this invention with reference to above statement.
More embodiment of the present invention can obtain from specification and dependent claims.
Hereinafter based on preferred embodiment with further specify with reference to the accompanying drawings the present invention.
Description of drawings
Fig. 1 illustrates the schematic diagram of the exhaust gas post-treatment device of implementing the method according to this invention;
Fig. 2 illustrates explanation NO xWearing out to its NO of storage catalytic converter xThe chart of the impact of storage capacity;
Fig. 3-Fig. 5 illustrates the chart of explanation the method according to this invention.
Embodiment
The exhaust gas post-treatment device of the schematically illustrated exhaust for the treatment of explosive motor of Fig. 1, NO is at first flow through in the exhaust 5 that wherein produces from explosive motor xStorage catalytic converter 10 and subsequently by being arranged on described NO xThe SCR catalytic converter 20 in the downstream of storage catalytic converter 10.
As can be seen from Figures 2 and 3, NO xEffective storage capacity of storage catalytic converter 10 is along with NO xProgressively aging (the reaching " 3 " corresponding to the curve among Fig. 3 " 1 ", " 2 ") of storage catalytic converter further descends, the relative low temperature zone that wherein in Fig. 3, is only schematically shown by " A ", deteriorated main accumulation owing to sulphate, in the relatively-high temperature zone by " B " expression in Fig. 3, deteriorated mainly owing to wearing out that thermal conductance causes.
The embodiment of the method according to this invention considers that described burn-in effects is hereinafter with reference to figure 4 and Fig. 5 explanation.
According to the present invention, along with NO xProgressively wearing out of storage catalytic converter 10 is from using NO xThe NO of storage catalytic converter 10 xLoad condition is transformed into the NH that uses SCR catalytic converter 20 as the standard (solid line among the comparison diagram 4a-4b) that triggers the regeneration stage 3Load is as the standard (dotted line among the comparison diagram 4a-4b) that triggers the regeneration stage.The regeneration stage triggers or moment of finishing is represented by rectangular curve or the rectangular signal shown in every kind of situation among Fig. 4 a and Fig. 4 b.
Using relatively new not aged NO x(corresponding to the zone of " I " among Fig. 2 indication) determines that the factor such as Fig. 4 a that trigger are depicted as NO in the situation of storage catalytic converter 10 xThe NO of storage catalytic converter 10 xAging NO is being used in load (unit is gram) x(corresponding to the zone of " II " among Fig. 2 indication) triggers shown in Fig. 4 b the NH by SCR catalytic converter 20 in the situation of storage catalytic converter 10 3Load (unit is gram) is determined.As hereinafter describing in detail.
1) state " I " (=not aged NO xThe storage catalytic converter)
According to Fig. 4 a, using relatively new not aged NO xIn the situation of storage catalytic converter 10 (state " I "), if NO xThe NO of storage catalytic converter 10 xLoad surpasses threshold value, namely meets the following conditions:
Load _ NO x＞threshold value _ NO x(t LNT, mf Eg) (1)
Then trigger the regeneration stage.Load _ NO wherein xExpression NO xThe NO of storage catalytic converter 10 xLoad, threshold value _ NO xThe threshold value of expression regulation, t LNTExpression NO xSubstrate temperature in the storage catalytic converter 10, mf EgExpression exhaust quality flow rate.
Simultaneously, at state " I ", the nominal value (" λ nominal value ") that depends on the air fuel ratio of the NOx load of NOx storage catalytic converter 10 and the ingress that the exhaust quality flow rate is set in NOx storage catalytic converter 10 is optimized the outflow that NOx in the NOx storage catalytic converter 10 transformed or minimized reducing agent by this way.
In addition, at state " I ", if meet the following conditions:
Load _ NO x＜threshold value _ NO X(t LNT, mf Eg) (2)
If or meet the following conditions,
λ _ downstream _ LNT＜threshold value 1_ λ (3)
In case namely (λ _ downstream _ LNT) drops to and is lower than threshold value (threshold value 1_ λ) air fuel ratio in the downstream of NOx storage catalytic converter 10, then finishes the regeneration stage.
2) state " II " (=aging NO xThe storage catalytic converter)
According to Fig. 4 b, for the situation (state " II ") of aging NOx storage catalytic converter 10, if the NH of SCR catalyst 20 3Load drops to and is lower than threshold value, namely meets the following conditions:
Load _ NH 3＜threshold value _ NH 3(t SCR, mf Eg) (4)
Then trigger the regeneration stage.Wherein, load _ NH 3The NH of expression SCR catalyst 20 3Load, threshold value _ NH 3The threshold value of expression regulation, t SCRThe substrate temperature of expression SCR catalyst 20, mf EgExpression exhaust quality flow rate.
Simultaneously, at state " II ", depend on the nominal value (" λ nominal value ") of the air fuel ratio of the NOx load of NOx storage catalytic converter 10 and the ingress that the exhaust quality flow rate is set in NOx storage catalytic converter 10, optimize by this way NH 3Regeneration.
In addition, at state " II ", if meet the following conditions:
Load _ NH 3＞threshold value _ NH 3(t SCR, mf Eg) (5)
If or meet the following conditions,
λ _ downstream _ SCR＜threshold value 2_ λ (6)
In case namely (the regeneration stage is then finished in λ _ downstream _ SCR) drop to less than threshold value (threshold value 2_ λ) to the air fuel ratio in the downstream of SCR catalytic converter 20.
3) transition region between state " I " and " II "
There is in following two conditions in transition region between state " I " and " II ":
Load _ NO x＞threshold value _ NO x_ AF (t LNT, mf Eg, AF) (7a)
Load _ NH 3＜threshold value _ NH 3_ AF (t SCR, mf Eg, AF) (7b)
These two conditions can be as the standard that triggers the regeneration stage.Wherein AF represents the aging factor as the ageing state feature of NOx storage catalytic converter 10, threshold value _ NO x_ AF and threshold value _ NH 3_ AF represents to depend on the threshold value of described aging factor.Therefore, at transition region, if the NOx load of NOx storage catalytic converter 10 surpasses threshold value (threshold value _ NO xIf _ AF) or the NH of SCR catalyst 20 3Load drops to and is lower than threshold value (threshold value _ NH 3_ AF), the regeneration stage then occurs, wherein said threshold value depends on the factor AF as the ageing state feature of NOx storage catalytic converter 10.
In addition, the transition region between state " I " and " II ", if satisfy in following two conditions one:
Load _ NO x＜threshold value _ NO x_ AF (t LNT, mf Eg, AF) (8a)
And
Load _ NH 3＞threshold value _ NH 3_ AF (t SCR, mf Eg, AF) (8b)
If or meet the following conditions:
λ _ downstream _ SCR＜threshold value 3_ λ (9)
In case namely (the regeneration stage is then finished in λ _ downstream _ SCR) drop to less than threshold value (threshold value 3_ λ) to the air fuel ratio in the downstream of SCR catalytic converter 20.
As for the air fuel ratio in the ingress of NOx storage catalytic converter 10, in the transition region between state " I " and " II ", carry out the setting of described air fuel ratio according to the chart among Fig. 5.
If the regeneration stage is triggered (step S10), judge (step S20) whether in the air fuel ratio (λ value) in NOx storage catalytic converter 10 downstreams less than threshold value (threshold value 3_ λ).If NO, then depend on the nominal value of the air fuel ratio of the NOx load of NOx storage catalytic converter 10 and the upstream that the exhaust quality flow rate is set NOx storage catalytic converter 10, the NOx in the optimization NOx storage catalytic converter 10 transforms and minimizes the outflow (step S30) of reducing agent by this way.Yet, if the air fuel ratio (λ value) in NOx storage catalytic converter 10 downstreams is during less than threshold value (threshold value 3_ λ), depend on the NOx load of NOx storage catalytic converter 10 and the nominal value (" λ nominal value ") that the exhaust quality flow rate is set air fuel ratio, by this way optimization NH 3Produce (step S40).

Claims (7)

1. method that operates exhaust gas post-treatment device, described exhaust gas post-treatment device has NO xStorage catalytic converter (10) and SCR catalyst (20), described NO xStorage catalytic converter (10) is used for storage from the nitrogen oxide of the exhaust (5) of explosive motor supply, and described SCR catalyst (20) is arranged on described NO xThe downstream of storage catalytic converter (10) is used for the nitrogen oxide that catalytic reduction optionally is fed to the exhaust of described SCR catalyst (20), wherein depend on the state variable value as the status flag of described exhaust gas post-treatment device, trigger for regenerating described NO xAt least one regeneration stage of storage catalytic converter (10), wherein, along with described NO xProgressively wearing out of storage catalytic converter (10) is transformed into the second pattern from first mode, at NO described in the described first mode xThe NO of storage catalytic converter (10) xLoad condition is used for the state variable of the standard in triggering regeneration stage as consideration, in described the second pattern, and the NH of described SCR catalyst (20) 3Load is as the state variable of considering for the standard that triggers the regeneration stage.
2. the method for claim 1 is characterized in that, in described first mode, if meet the following conditions:
Load _ NO x＞threshold value _ NO x(t LNT, mf Eg),
Then trigger the regeneration stage, wherein load _ NO xRepresent described NO xThe NO of storage catalytic converter (10) xLoad, threshold value _ NO xThe expression threshold value, t LNTRepresent described NO xThe substrate temperature of storage catalytic converter (10), and mf EgExpression exhaust quality flow rate.
3. the method for claim 1 is characterized in that, in described the second pattern, if meet the following conditions:
Load _ NH 3＜threshold value _ NH 3(t SCR, mf Eg),
Then trigger the regeneration stage, wherein load _ NH 3The NH that represents described SCR catalyst (20) 3Load, threshold value _ NH 3The expression threshold value, t SCRThe substrate temperature that represents described SCR catalyst (20), and mf EgExpression exhaust quality flow rate.
4. such as any one the described method in the above-mentioned claim, it is characterized in that, depend on described NO xThe ageing state control NO of storage catalytic converter (10) xThe air fuel ratio of the ingress of storage catalytic converter (10).
5. method as claimed in claim 4 is characterized in that, along with described NO xProgressively wearing out of storage catalytic converter (10), described control is associated with described NO xThe NO of the optimization in the storage catalytic converter xTransform, be transformed into control and be associated with described NO xThe NH of the optimization in the storage catalytic converter 3Produce.
6. the method for claim 1 is characterized in that, along with NO xProgressively wearing out of storage catalytic converter (10) is from NO xThe nominal value of the air fuel ratio of the ingress of storage catalytic converter (10) arrives NO in 0.90 to 1.0 scope internal conversion xThe nominal value of the air fuel ratio of the ingress of storage catalytic converter (10) is in 0.80 to 0.90 scope.
7. exhaust gas post-treatment device, described exhaust gas post-treatment device has NO xStorage catalytic converter (10) and SCR catalyst (20), described NO xStorage catalytic converter (10) is used for storage from the nitrogen oxide of the exhaust (5) of explosive motor supply, and described SCR catalyst (20) is arranged on described NO xThe downstream of storage catalytic converter (10) is used for optionally, and catalytic reduction is fed to NO xNitrogen oxide in the exhaust of storage catalytic converter (10), wherein said exhaust gas post-treatment device also comprise for definite described NO xThe NO of storage catalytic converter (10) xThe device of load, be used for to determine the NH of SCR catalyst (20) 3The device of load, be used for triggering described NO xThe equipment in the regeneration stage of storage catalytic converter (10) wherein, is used for triggering described NO xThe device design in the regeneration stage of storage catalytic converter (10) is for depending on described NO xThe ageing state of storage catalytic converter (10) is based on described NO xThe NO of storage catalytic converter (10) xLoad or based on the NH of described SCR catalyst (20) 3The load triggers regeneration stage.
CN2009101465240A 2008-05-28 2009-05-26 Exhaust gas after-treatment device and method for operating the same Expired - Fee Related CN101592060B (en)

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DE102008025520A DE102008025520B4 (en) 2008-05-28 2008-05-28 A method for operating an exhaust aftertreatment device, and exhaust aftertreatment device

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CN101592060B true CN101592060B (en) 2013-09-18

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CN104234802B (en) * 2014-07-14 2017-01-11 浙江大学 SCR (Selective Catalytic Reduction) catalyst aging judgment method based on NOx feedback and ammonia storage prediction
AT516469B1 (en) 2014-11-07 2018-06-15 Avl List Gmbh METHOD FOR TARGETED GENERATION OF NH3 DURING THE REGENERATION PROCESS OF NOX MEMORY CATALYST

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