DE202014103641U1 - Exhaust gas aftertreatment with bypass for regeneration - Google Patents
Exhaust gas aftertreatment with bypass for regeneration Download PDFInfo
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- DE202014103641U1 DE202014103641U1 DE201420103641 DE202014103641U DE202014103641U1 DE 202014103641 U1 DE202014103641 U1 DE 202014103641U1 DE 201420103641 DE201420103641 DE 201420103641 DE 202014103641 U DE202014103641 U DE 202014103641U DE 202014103641 U1 DE202014103641 U1 DE 202014103641U1
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- nitrogen oxide
- exhaust aftertreatment
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- 230000008929 regeneration Effects 0.000 title claims description 10
- 238000011069 regeneration method Methods 0.000 title claims description 10
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 147
- 239000003054 catalyst Substances 0.000 claims abstract description 86
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 48
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 48
- 239000011593 sulfur Substances 0.000 claims abstract description 48
- 239000007789 gas Substances 0.000 claims abstract description 42
- 238000002485 combustion reaction Methods 0.000 claims abstract description 19
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 10
- 230000003197 catalytic effect Effects 0.000 claims abstract description 8
- 239000004071 soot Substances 0.000 claims description 12
- 238000010531 catalytic reduction reaction Methods 0.000 claims description 10
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- 238000006477 desulfuration reaction Methods 0.000 claims description 7
- 230000023556 desulfurization Effects 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 6
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 3
- 239000003344 environmental pollutant Substances 0.000 description 7
- 231100000719 pollutant Toxicity 0.000 description 7
- 239000000446 fuel Substances 0.000 description 6
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 239000000758 substrate Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 150000003464 sulfur compounds Chemical class 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000018537 nitric oxide storage Effects 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9481—Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start
- B01D53/949—Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start for storing sulfur oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
- B01D53/9413—Processes characterised by a specific catalyst
- B01D53/9422—Processes characterised by a specific catalyst for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/96—Regeneration, reactivation or recycling of reactants
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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
- F01N3/10—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
- F01N3/2053—By-passing catalytic reactors, e.g. to prevent overheating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9459—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts
- B01D53/9477—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts with catalysts positioned on separate bricks, e.g. exhaust systems
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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
- F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
- F01N2240/36—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being an exhaust flap
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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
- F01N2410/00—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
- F01N2410/02—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device in case of high temperature, e.g. overheating of catalytic reactor
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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
- F01N2410/00—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
- F01N2410/03—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device in case of low temperature
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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
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
- F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
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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
- F01N3/10—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]
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
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- Materials Engineering (AREA)
- Toxicology (AREA)
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- Sustainable Development (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
Eine Abgasnachbehandlungsvorrichtung (5) für eine Brennkraftmaschine (3) und mit einem Schwefelspeicher (8) und einem stromabwärts des Schwefelspeichers (8) angeordneten NOx-speicherkatalysator (9), gekenn-zeichnet durch eine erste Bypassleitung (11), die einen stromaufwärts des Schwefelspeichers (8) angeordneten Eingang und einen zwischen dem Schwefelspeicher (8) und dem NOx-speicherkatalysator (9) angeordneten Ausgang aufweist, und durch eine zweite Bypassleitung (12), die einen zwischen der Einmündung der ersten Bypassleitung (11) und dem Stickoxidspeicherkatalysator (9) angeordneten Eingang und einen stromabwärts des Stickoxidspeicherkatalysators (9) angeordneten Ausgang aufweist.An exhaust gas aftertreatment device (5) for an internal combustion engine (3) and with a sulfur store (8) and a NOx storage catalytic converter (9) arranged downstream of the sulfur store (8), characterized by a first bypass line (11), the one upstream of the sulfur store (8) arranged input and an output arranged between the sulfur store (8) and the NOx storage catalyst (9), and through a second bypass line (12) which has a between the confluence of the first bypass line (11) and the nitrogen oxide storage catalyst (9 ) arranged input and a downstream of the nitrogen oxide storage catalyst (9) arranged output.
Description
Die Erfindung betrifft eine Abgasnachbehandlungsvorrichtung für eine Brennkraftmaschine und ein Kraftfahrzeug mit einer Brennkraftmaschine und einer mit der Brennkraftmaschine verbundenen Abgasnachbehandlungsvorrichtung.The invention relates to an exhaust aftertreatment device for an internal combustion engine and a motor vehicle with an internal combustion engine and an exhaust aftertreatment device connected to the internal combustion engine.
Aufgrund stetig steigender Anforderungen an die Abgasreinheit von Kraftfahrzeugen wird versucht, die Entstehung von Schadstoffen bei der Verbrennung des Kraftstoffes im Verbrennungsmotor zu verhindern oder zu verringern und die entstandenen Schadstoffe im Abgas chemisch oder physikalisch zu reduzieren. Insbesondere wird dabei eine Verringerung des Ausstoßes an Stickoxiden, kurz NOx, angestrebt.Due to steadily increasing demands on the exhaust gas purity of motor vehicles is trying to prevent or reduce the formation of pollutants in the combustion of the fuel in the internal combustion engine and chemically or physically reduce the resulting pollutants in the exhaust. In particular, a reduction in the emission of nitrogen oxides, NOx for short, is aimed for.
Um die Anforderungen zu erfüllen, weisen moderne Kraftfahrzeuge Abgasnachbehandlungsvorrichtungen auf, welche den Schadstoffgehalt im Abgas reduzieren, indem sie die Schadstoffe in weniger schädliche Gase umwandeln. Beispiele solcher Abgasnachbehandlungsvorrichtungen, die insbesondere im Zusammenspiel mit Dieselmotoren üblich sind, sind Dieselrußpartikelfilter (Diesel Particulate Filter, DPF), Diesel-Oxidationskatalysatoren (Diesel Oxidation Catalyst, DOC) oder sogenannte Lean NOx Traps (LNT, NOx Speicherkatalysatoren).To meet the requirements, modern motor vehicles have exhaust aftertreatment devices that reduce the pollutant content in the exhaust by converting the pollutants into less harmful gases. Examples of such exhaust aftertreatment devices which are particularly common with diesel engines are Diesel Particulate Filter (DPF), Diesel Oxidation Catalyst (DOC) or Lean NOx Trap (LNT) catalysts.
Die verschiedenen Abgasnachbehandlungseinheiten entfalten üblicherweise ihre bestmögliche Funktion in bestimmten Temperaturfenstern. Unterhalb einer Mindesttemperatur ist häufig eine katalytische Wirkung zu gering, oberhalb einer Höchsttemperatur besteht die Gefahr einer Beschädigung des Substrates der Abgasnachbehandlungseinheit. Außerdem können manche Abgasnachbehandlungseinheiten in unterschiedlichen Betriebsmodi betrieben werden, für die ebenfalls unterschiedliche Temperaturanforderungen gelten. Beispielsweise kann für eine Regeneration eines Katalysators oder Rußfilters eine zeitweilig bestimmte Abgaszusammensetzung (z. B. unterstöchiometrisch) und/oder erhöhte Temperatur vorgesehen sein, um einen adsorbierten oder eingelagerten Schadstoff zu lösen oder abzubrennen. Zudem können Reduktionsmittel eingesetzt werden, um die Regeneration oder katalytische Reaktionen zu unterstützen.The various exhaust aftertreatment units usually perform their best function in certain temperature windows. Below a minimum temperature is often a catalytic effect too low, above a maximum temperature there is a risk of damage to the substrate of the exhaust aftertreatment unit. In addition, some exhaust aftertreatment units may be operated in different operating modes, which also have different temperature requirements. For example, for regeneration of a catalyst or soot filter, a temporarily determined exhaust gas composition (eg, substoichiometric) and / or elevated temperature may be provided to dissolve or burn off an adsorbed or stored pollutant. In addition, reducing agents can be used to aid regeneration or catalytic reactions.
Um möglichst geringe Schadstoffausstöße zu erzielen und gleichzeitig eine wechselseitige Verträglichkeit der verschiedenen in einem Abgasstrang einer Brennkraftmaschine vorgesehenen Abgasnachbehandlungseinheiten zu erreichen, ist mithin einiger Aufwand notwendig.In order to achieve the lowest possible pollutant emissions and at the same time to achieve mutual compatibility of the various provided in an exhaust line of an internal combustion engine exhaust aftertreatment units, therefore, some effort is necessary.
Die Erfindung macht es sich daher zur Aufgabe, eine verbesserte Abgasnachbehandlungsvorrichtung einzuführen, die eine besonders wirksame Abgasnachbehandlung erlaubt.The invention therefore has for its object to introduce an improved exhaust aftertreatment device, which allows a particularly effective exhaust aftertreatment.
Ein erster Aspekt der Erfindung führt daher eine Abgasnachbehandlungsvorrichtung für eine Brennkraftmaschine ein, die mit einem Schwefelspeicher und einem stromabwärts des Schwefelspeichers angeordneten Stickoxidspeicherkatalysator ausgestattet ist. Erfindungsgemäß sind ferner eine erste Bypassleitung, die einen stromaufwärts des Schwefelspeichers angeordneten Eingang und einen zwischen dem Schwefelspeicher und dem Stickoxidspeicherkatalysator angeordneten Ausgang aufweist, und eine zweite Bypassleitung, die einen zwischen der Einmündung der ersten Bypassleitung und dem Stickoxidspeicherkatalysator angeordneten Eingang und einen stromabwärts des Stickoxidspeicherkatalysators angeordneten Ausgang aufweist, vorgesehen.A first aspect of the invention therefore introduces an exhaust aftertreatment device for an internal combustion engine equipped with a sulfur reservoir and a nitrogen oxide storage catalyst disposed downstream of the sulfur reservoir. According to the invention, a first bypass line, which has an input disposed upstream of the sulfur reservoir and an outlet arranged between the sulfur storage and the nitrogen oxide storage catalyst, and a second bypass line, which arranged an input disposed between the junction of the first bypass line and the nitrogen oxide storage catalyst and a downstream of the nitrogen oxide storage catalyst Output has provided.
Der Schwefelspeicher kann schwefelhaltige Verbindungen, üblicherweise Schwefeloxid, adsorbieren und so dem Abgas entziehen. Der Schwefel beeinträchtigt die Wirkung anderer Abgasnachbehandlungseinheiten und kann diese unter Umständen sogar schädigen. Da die Aufnahmekapazität des Schwefelspeichers naturgemäß begrenzt ist, muss der Schwefelspeicher regeneriert werden, wobei der adsorbierte Schwefel unter Erhöhung der Temperatur des Schwefelspeichers bei unterstöchiometrischen Bedingungen aus dem Schwefelspeicher losgelöst wird. Der losgelöste Schwefel kann nun unter Verwendung der zweiten Bypassleitung an dem Stickoxidspeicherkatalysator vorbeigeleitet werden, so dass der losgelöste Schwefel nicht wieder von dessen Substrat aufgenommen wird. Genau so ist es möglich, etwaigen durch den Schwefelspeicher zum Stickoxidspeicherkatalysator gelangten und dort unerwünscht adsorbierten Schwefel aus dem Stickoxidspeicherkatalysator zu lösen. In vielen Betriebsweisen der Brennkraftmaschine, beispielsweise bei niedriger Motorleistung, reicht die Abgastemperatur des bereits durch den Schwefelspeicher geströmten Abgases nicht aus, um eine solche Regeneration beziehungsweise Entschwefelung des Stickoxidspeicherkatalysators durchzuführen. Hierfür ist es bekannt, durch Einspritzung von Kraftstoff, beispielsweise per Spätnacheinspritzung in der Brennkraftmaschine, die Abgastemperatur zu erhöhen, was jedoch zu einer unerwünschten Erhöhung des Kraftstoffverbrauchs führt. Die Erfindung ermöglicht es, diesen Nachteil zu verringern, indem das Abgas der Brennkraftmaschine für eine Entschwefelung des Stickoxidspeicherkatalysators über die erste Bypassleitung an dem Schwefelspeicher vorbeigeleitet wird und so die zu entschwefelnden Abgasnachbehandlungseinheiten mit einer höheren Temperatur erreicht.The sulfur storage can adsorb sulfur compounds, usually sulfur oxide, and thus extract the exhaust gas. The sulfur affects the performance of other exhaust aftertreatment units and may even damage them. Since the absorption capacity of the sulfur storage is naturally limited, the sulfur storage must be regenerated, the adsorbed sulfur is released under increasing the temperature of the sulfur storage under stoichiometric conditions from the sulfur storage. The separated sulfur can now be bypassed using the second bypass line to the nitrogen oxide storage catalyst, so that the dissolved sulfur is not taken up again from the substrate. It is also possible to dissolve any sulfur that has passed through the sulfur reservoir to the nitrogen oxide storage catalyst and adsorbs it undesirably from the nitrogen oxide storage catalyst. In many modes of operation of the internal combustion engine, for example, at low engine power, the exhaust gas temperature of the already exhausted through the sulfur storage exhaust gas is not sufficient to perform such a regeneration or desulfurization of the nitrogen oxide storage catalyst. For this purpose, it is known to increase the exhaust gas temperature by injection of fuel, for example, by late post-injection in the internal combustion engine, but this leads to an undesirable increase in fuel consumption. The invention makes it possible to reduce this disadvantage by passing the exhaust gas of the internal combustion engine for desulfurization of the nitrogen oxide storage catalyst past the sulfur reservoir via the first bypass line and thus reaching the exhaust gas aftertreatment units to be desulfurized at a higher temperature.
Dabei kann in Abhängigkeit der jeweiligen Abgastemperaturen und erforderlichen Substrattemperaturen ein Mischungsverhältnis von durch die Bypassleitung geleitetem Abgas einerseits und durch den Schwefelspeicher geleiteten Abgas andererseits frei gewählt werden, um die gewünschte Abgastemperatur am Eingang des Stickoxidspeicherkatalysators einzustellen. In this case, depending on the respective exhaust gas temperatures and required substrate temperatures, a mixing ratio of exhaust gas passed through the bypass line, on the one hand, and exhaust gas conducted through the sulfur reservoir, on the other hand, can be freely selected to set the desired exhaust gas temperature at the inlet of the nitrogen oxide storage catalytic converter.
Die Erfindung ermöglicht dadurch die Entschwefelung beziehungsweise Regeneration der Abgasnachbehandlungseinheiten bei reduziertem Einsatz von Kraftstoff für diese Zwecke. Gleichwohl kann eine Einspritzung von Reduktionsmitteln oder Kraftstoff vorgesehen sein, beispielsweise stromaufwärts des Stickoxidspeicherkatalysators und/oder stromaufwärts des Schwefelspeichers.The invention thereby enables the desulfurization or regeneration of the exhaust aftertreatment units with reduced use of fuel for these purposes. However, an injection of reducing agents or fuel may be provided, for example, upstream of the nitrogen oxide storage catalyst and / or upstream of the sulfur reservoir.
Der Schwefelspeicher kann beispielsweise auch ein Dieseloxidationskatalysator oder ein NOx speichernder Katalysator sein. Solche Abgasnachbehandlungseinheiten können Schwefel adsorbieren.The sulfur reservoir can also be, for example, a diesel oxidation catalyst or a NOx-storing catalyst. Such exhaust aftertreatment units can adsorb sulfur.
Die Abgasnachbehandlungsvorrichtung der Erfindung kann über einen stromabwärts des Stickoxidspeicherkatalysators angeordneten Selective-Catalytic-Reduction-Katalysator (SCR-Katalysator) verfügen. Der SCR-Katalysator kann innerhalb oder außerhalb der zweiten Bypassleitung angeordnet sein. Der SCR-Katalysator kann neben herkömmlichen Ausführungsvarianten beispielsweise auch als Rußfilter mit einer SCR-katalytischen Beschichtung ausgeführt sein.The exhaust aftertreatment device of the invention may have a selective catalytic reduction (SCR) catalyst disposed downstream of the nitrogen oxide storage catalyst. The SCR catalyst may be located inside or outside the second bypass line. The SCR catalyst can be designed in addition to conventional variants, for example, as a soot filter with an SCR catalytic coating.
Der Stickoxidspeicherkatalysator kann insbesondere ein LNT mit aktiver Regeneration (z. B. unterstöchiometrisch) oder ein passiver Stickoxidadsorber (PNA) sein. Der Stickoxidspeicherkatalysator kann aber auch als ein Rußpartikelfilter mit einer Stickoxidspeicherbeschichtung ausgeführt sein.The nitrogen oxide storage catalyst may in particular be an LNT with active regeneration (eg substoichiometric) or a passive nitrogen oxide adsorber (PNA). However, the nitrogen oxide storage catalyst may also be embodied as a soot particle filter with a nitrogen oxide storage coating.
Besitzt die Abgasnachbehandlungsvorrichtung einen SCR-Katalysator, kann sie auch eine dritte Bypassleitung aufweisen, die einen zwischen dem Stickoxidspeicherkatalysator und dem Selective-Catalytic-Reduction-Katalysator angeordneten Eingang und einen stromabwärts des Selective-Catalytic-Reduction-Katalysators angeordneten Ausgang besitzt. Die dritte Bypassleitung kann verwendet werden, um bei einer Entschwefelung des Schwefelspeichers die gelösten Schwefelverbindungen auch an dem SCR-Katalysator vorbeizuführen, falls dieser nicht stromaufwärts des Ausgangs der zweiten Bypassleitung angeordnet ist. Insbesondere kann die dritte Bypassleitung aber auch bei Ausführungsformen der erfindungsgemäßen Abgasnachbehandlungsvorrichtung verwendet werden, bei denen der Stickoxidspeicherkatalysator als Rußpartikelfilter mit einer Stickoxidspeicherbeschichtung ausgeführt ist. Die dritte Bypassleitung kann hierbei verwendet werden, um die während eines Abbrennvorgangs des in dem als Rußpartikelfilter mit katalytischer Beschichtung ausgeführten Stickoxidspeicherkatalysator eingelagerten Rußes entstehenden hohen Abgastemperaturen an dem SCR-Katalysator vorbeizuleiten und diesen dadurch vor einer Beschädigung zu schützen.If the exhaust aftertreatment device has an SCR catalyst, it may also have a third bypass line having an inlet located between the nitrogen oxide storage catalyst and the selective catalytic reduction catalyst and an exit downstream of the selective catalytic reduction catalyst. The third bypass line can be used to also lead the dissolved sulfur compounds on the SCR catalyst in the case of desulfurization of the sulfur reservoir, if this is not arranged upstream of the output of the second bypass line. In particular, however, the third bypass line can also be used in embodiments of the exhaust gas aftertreatment device according to the invention, in which the nitrogen oxide storage catalytic converter is designed as a soot particle filter with a nitrogen oxide storage coating. In this case, the third bypass line can be used to pass the high exhaust-gas temperatures arising during a burning-off process of the soot stored in the soot particle filter with catalytic coating into the SCR catalytic converter, thereby protecting it from damage.
Die Abgasnachbehandlungsvorrichtung kann einen stromabwärts des Stickoxidspeicherkatalysators angeordneten passiven SCR-Katalysator umfassen. Ist ein SCR-Katalysator vorgesehen, wird der passive SCR-Katalysator stromabwärts dieses Katalysators angeordnet. Ein passiver SCR-Katalysator kommt ohne eine Ureainjektion aus und kann beispielsweise von dem Schwefelspeicher und/oder dem Stickoxidspeicherkatalysator bei einer Regeneration mit Kraftstoffeinspritzung beziehungsweise fettem Abgasgemisch erzeugten Ammoniak für die Reduktion von Stickoxiden verwerten. Außerdem ist ein SCR-Katalysator verhältnismäßig schwefeltolerant, weshalb er stromabwärts der vorhandenen Bypassleitungen angeordnet sein kann. Es ist also vorteilhaft möglich, die Aufgabe der selektiven katalytischen Reaktion auf zwei Abgasnachbehandlungseinheiten aufzuteilen, wovon eine auch zur Verfügung steht, wenn das Abgas zeitweilig ganz oder teilweise durch die zweite Bypassleitung an dem Stickoxidspeicherkatalysator vorbeigeleitet wird.The exhaust aftertreatment device may include a passive SCR catalyst disposed downstream of the nitrogen oxide storage catalyst. If an SCR catalyst is provided, the passive SCR catalyst is placed downstream of this catalyst. A passive SCR catalyst can do without a urea injection and can utilize, for example, ammonia for the reduction of nitrogen oxides produced by the sulfur storage and / or the nitrogen oxide storage catalyst during a regeneration with fuel injection or a rich exhaust gas mixture. In addition, an SCR catalyst is relatively sulfur tolerant and therefore may be located downstream of existing bypass lines. Thus, it is advantageously possible to divide the task of selective catalytic reaction to two exhaust aftertreatment units, one of which is also available when the exhaust gas is temporarily bypassed all or part of the nitrogen oxide storage catalyst through the second bypass line.
Die Abgasnachbehandlungsvorrichtung kann mit einer Ventilanordnung ausgestattet sein, die ausgebildet ist, jeweilige Anteile einer Gesamtdurchflussmenge an Abgas in der Abgasnachbehandlungsvorrichtung in den Bypassleitungen variabel einzustellen. Die Abgasnachbehandlungsvorrichtung kann dabei insbesondere eine mit der Ventilanordnung verbundene Steuereinheit aufweisen, die ausgebildet ist, die Ventilanordnung zu steuern und dabei während eines Entschwefelungsvorgangs des Schwefelspeichers eine Durchflussmenge an Abgas durch den Stickoxidspeicherkatalysator zu reduzieren und während einer Regenerierung des Stickoxidspeicherkatalysators eine Durchflussmenge an Abgas durch den Schwefelspeicher zu reduzieren.The exhaust aftertreatment device may be provided with a valve assembly configured to variably set respective proportions of a total flow rate of exhaust gas in the exhaust aftertreatment device in the bypass lines. The exhaust aftertreatment device may in particular have a control unit connected to the valve arrangement, which is designed to control the valve arrangement and thereby reduce a flow rate of exhaust gas through the nitrogen oxide storage catalyst during a desulfurization process of the sulfur storage and during a regeneration of the nitrogen oxide storage catalyst, a flow rate of exhaust gas through the sulfur storage to reduce.
Ein zweiter Erfindungsaspekt betrifft ein Kraftfahrzeug mit einer Brennkraftmaschine und einer mit der Brennkraftmaschine verbundenen Abgasnachbehandlungsvorrichtung gemäß dem ersten Erfindungsaspekt.A second aspect of the invention relates to a motor vehicle having an internal combustion engine and an exhaust gas aftertreatment device connected to the internal combustion engine according to the first aspect of the invention.
Die Erfindung wird nachfolgend anhand von Abbildungen näher erläutert. Es zeigen:The invention will be explained in more detail with reference to figures. Show it:
Erfindungsgemäß weist die Abgasnachbehandlungsvorrichtung eine erste Bypassleitung
Die Abgasnachbehandlungsvorrichtung der Erfindung weist außerdem noch eine zweite Bypassleitung
Dies ist insbesondere bei einer Entschwefelung des Schwefelspeichers
Die dritte Bypassleitung
Für das in
Obwohl die Erfindung im Detail durch Ausführungsbeispiele von bevorzugten Ausführungsformen näher illustriert und beschrieben wurde, ist die Erfindung nicht durch die offenbarten Beispiele eingeschränkt. Variationen der Erfindung können vom Fachmann aus den gezeigten Ausführungsbeispielen abgeleitet werden, ohne den Schutzumfang der Erfindung, wie er in den Ansprüchen definiert wird, zu verlassen.Although the invention has been further illustrated and described in detail by way of embodiments of preferred embodiments, the invention is not limited by the disclosed examples. Variations of the invention may be derived by those skilled in the art from the illustrated embodiments without departing from the scope of the invention as defined in the claims.
BezugszeichenlisteLIST OF REFERENCE NUMBERS
- 11
- Kraftfahrzeug motor vehicle
- 22
- Rad wheel
- 33
- Brennkraftmaschine Internal combustion engine
- 44
- Abgaskrümmer exhaust manifold
- 55
- Abgasnachbehandlungsvorrichtung exhaust aftertreatment device
- 66
- Abgasnachbehandlungseinheit exhaust gas treatment unit
- 77
- Auspuff Exhaust
- 88th
- Schwefelspeicher sulfur storage
- 99
- Stickoxidspeicherkatalysator Nitrogen oxide storage catalyst
- 1010
- SCR-Katalysator SCR catalyst
- 1111
- erste Bypassleitung first bypass line
- 1212
- zweite Bypassleitung second bypass line
- 1313
- dritte Bypassleitung third bypass line
- 1414
- Ventil Valve
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DE102014215270.4A DE102014215270A1 (en) | 2014-08-04 | 2014-08-04 | Exhaust gas aftertreatment with bypass for regeneration |
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