SE537709C2 - Arrangement and method for controlling the distribution of nitrogen monoxide and nitrogen dioxide in an exhaust pipe with two oxidation catalysts - Google Patents

Arrangement and method for controlling the distribution of nitrogen monoxide and nitrogen dioxide in an exhaust pipe with two oxidation catalysts Download PDF

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SE537709C2
SE537709C2 SE1251092A SE1251092A SE537709C2 SE 537709 C2 SE537709 C2 SE 537709C2 SE 1251092 A SE1251092 A SE 1251092A SE 1251092 A SE1251092 A SE 1251092A SE 537709 C2 SE537709 C2 SE 537709C2
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oxidation catalyst
exhaust
exhaust gases
line
nitrogen
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SE1251092A
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Swedish (sv)
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SE1251092A1 (en
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Håkan Sarby
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Scania Cv Ab
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Priority to SE1251092A priority Critical patent/SE537709C2/en
Priority to DE112013004219.3T priority patent/DE112013004219T5/en
Priority to PCT/SE2013/051086 priority patent/WO2014051500A1/en
Publication of SE1251092A1 publication Critical patent/SE1251092A1/en
Publication of SE537709C2 publication Critical patent/SE537709C2/en

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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
    • 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
    • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
    • F01N3/106—Auxiliary oxidation 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
    • F01N13/0093—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 the purifying devices are of the same type
    • 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
    • F01N3/023—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 using means for regenerating the filters, e.g. by burning trapped particles
    • F01N3/0236—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 using means for regenerating the filters, e.g. by burning trapped particles using turbine waste gate valve
    • 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
    • F01N3/103—Oxidation catalysts for HC and CO only
    • 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
    • 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
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • F02B37/013—Engines characterised by provision of pumps driven at least for part of the time by exhaust with exhaust-driven pumps arranged in series
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • F02B37/12—Control of the pumps
    • F02B37/18—Control of the pumps by bypassing exhaust from the inlet to the outlet of turbine or to the atmosphere
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B39/00—Component parts, details, or accessories relating to, driven charging or scavenging pumps, not provided for in groups F02B33/00 - F02B37/00
    • F02B39/02—Drives of pumps; Varying pump drive gear ratio
    • 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
    • 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

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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)
  • Materials Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

16 Sarnmandrag Föreliggande uppfinning avser ett arrangemang och ett förfarande för behandling avavgaser från en förbränningsmotor (2). Arrangemanget innefattar en avgasíedning (3)som leder ut avgaserna från förbränníngsrnotorn (2), en turbín (4, 12, 27) med vilkenenergi utvinns ur avgaserna i avgasledning (3), en bypassledning (14) som innefattarett inlopp (14a) där avgaser mottas från avgasiedníngen (3) i en position uppströmsturbinen (4, 12, 27) och ett utlopp (1411) där avgaser leds tillbaka tiil avgasledningen(3) i en position nedströms turbinen (4, 12, 27). En första oxidationskatalysator (15) äranordnad i bypassledningen (14) och en andra oxidationskatalysator (19) är anordnad iavgasledningen (3) i en position nedströms bypassledningen utlopp (1419). Arrange-manget innefattar styrmedel (11, 13, 16, 17) som är anpassat att reglera flöde ooh/ellertemperaturen på avgaser som leds genom den första oxidationskatalysatorn (15) i by-passledningen (14) så att den första oxidationskatalysatorn (15) och den andra oxida-tionskatalysatorn (19) tillsammans tillhandahåller en oxidation av kvävernonoxid (NO)till kvävedioxid (N02) i en mängd så att avgaserna som lämnar den andra oxidations- katalysatorn (19) har en önskad fördelning av kvävemonoxid (NO) och kvävedioxid (N02)- (Fig. 1) The present invention relates to an arrangement and a method for treating exhaust gases from an internal combustion engine (2). The arrangement comprises an exhaust line (3) which discharges the exhaust gases from the combustion engine (2), a turbine (4, 12, 27) with which energy is extracted from the exhaust gases in the exhaust line (3), a bypass line (14) comprising an inlet (14a) where exhaust gases received from the exhaust line (3) in a position upstream of the turbine (4, 12, 27) and an outlet (1411) where exhaust gases are led back to the exhaust line (3) in a position downstream of the turbine (4, 12, 27). A first oxidation catalyst (15) is provided in the bypass line (14) and a second oxidation catalyst (19) is arranged in the exhaust line (3) in a position downstream of the bypass line outlet (1419). The arrangement comprises control means (11, 13, 16, 17) which are adapted to control the desert ooh / or temperature of exhaust gases passed through the first oxidation catalyst (15) in the bypass line (14) so that the first oxidation catalyst (15) and the second oxidation catalyst (19) together provides an oxidation of nitric oxide (NO) to nitrogen dioxide (NO 2) in an amount such that the exhaust gases leaving the second oxidation catalyst (19) have a desired distribution of nitrogen monoxide (NO) and nitrogen dioxide ( NO2) - (Fig. 1)

Description

Arrangemang och forfarande for att styra fordelningen av kvavemonoxid och kvavedioxid i en avgasledning med tvA. oxidationskatalysatorer UPPFINNINGENS BAKGRUND OCH KAND TEKNIK Uppfinningen avser ett arrangemang och ett forfarande for behandling av avgaser fran en forbranningsmotor enligt patentkravens 1 och 10 ingresser. Arrangement and procedure for controlling the distribution of nitrogen monoxide and nitrogen dioxide in an exhaust line with tvA. BACKGROUND OF THE INVENTION AND PRIOR ART The invention relates to an arrangement and a method for treating exhaust gases from an internal combustion engine according to the preambles of claims 1 and 10.

For att reducera utslappen av kvaveoxider NOx fran forbranningsmotorer anvands bl.a. en teknik som benamns SCR (Selective Catalytic Reduction). Denna teknik innebar att en lOsning av urea tillfors i en bestamd dos till avgasema i en avgasledning. Urealos- ning kan sprayas in i avgasledningen varefter den finfordelade urealosningen forangas i kontakt med de heta avgasema sa att ammoniak bildas. Blandningen av ammoniak och avgaser leds darefter genom en SCR-katalysator. Kvavet hos kvaveoxiderna i avgaserna reagerar har med kvavet i ammoniaken sâ att kvavgas bildas. Syret hos kvave- oxidema reagerar med vatet i ammoniaken sâ att vatten bildas. Kvaveoxidema i avgasema reduceras saledes i katalysatom till kvavgas och vattenanga. Med en korrekt dosering av urea kan forbranningsmotoms utslapp av kvaveoxider i en stor utstrackning reduceras. In order to reduce the emission of nitrogen oxides NOx from internal combustion engines, e.g. a technique called SCR (Selective Catalytic Reduction). This technique meant that a solution of urea was supplied at a certain dose to the exhaust gases in an exhaust line. Urea solution can be sprayed into the exhaust line, after which the finely divided urea solution is evaporated in contact with the hot exhaust gases so that ammonia is formed. The mixture of ammonia and exhaust gases is then passed through an SCR catalyst. The nitrogen of the nitrogen oxides in the exhaust gases reacts with the nitrogen in the ammonia so that nitrogen gas is formed. The oxygen of the nitrogen oxides reacts with the water in the ammonia to form water. The nitrogen oxides in the exhaust gases are thus reduced in the catalyst to nitrogen gas and water vapor. With the correct dosage of urea, the emissions of nitrogen oxides from the internal combustion engine can be greatly reduced.

Kvaveoxider NOx i avgaser bestar av kvavemonoxid NO och kvavedioxid NO2. SCRkatalysatorers fat-maga att reducera mangden kvaveoxider i avgaser är optimal dâ avgasema innehaller lika mycket kvavemonoxid och kvavedioxid. Andelen kviivedioxid ska saledes vara 50 %. Avgaser fran i synnerhet dieselmotorer innehaller vanligtvis en betydligt mindre andel kvavedioxid an kvavemonoxid. For att Oka andelen kvavedi- oxid är det kant att anordna en oxidationskatalysator DOC (Diesel Oxidation Catalyst) i avgasledningen i en position uppstroms SCR-katalysatom. En oxidationskatalysator oxiderar kvavemonoxid NO till kvavedioxid NO2. Darmed kan andelen kvavedioxid NO2 i avgasema oka till den niva vid vilken SCR-katalysatom tillhandahafter en optimal formaga att reducera kvaveoxider NOx. 1 537 709 En oxidationskatalysators formaga att oxidera kvavemonoxid NO till kvavedioxid NO2 varierar med avgasernas temperatur och Nide. Eftersom avgasernas temperatur och flOde varierar under drift av en forbranningsmotor kan en oxidationskatalysator inte alltid leverera den onskade fordelningen mellan de tva slagen av kvaveoxid. Om en oxidationskatalysator dimensioneras for att oxidera kvaveoxider i avgaser vid en me- deltemperatur hos avgaserna erhalls en for lag andel kvavedioxid NO2 vid raga avgastemperaturer och en for hog andel kvavedioxid NO2 vid hoga avgastemperaturer. En for lag andel kvavedioxid NO2 resulterar i en dalig verkningsgrad i SCR-katalysator. En for hog andel kvavedioxid NO2 resulterar i att lustgas bildas i kontakt med inspru- tad urealosning. Lustgas är en stark vaxthusgas. Nitrogen oxides NOx in exhaust gases consist of nitrogen monoxide NO and nitrogen dioxide NO2. The barrel capacity of SCR catalysts to reduce the amount of nitrogen oxides in exhaust gases is optimal as the exhaust gases contain the same amount of nitrogen monoxide and nitrogen dioxide. The proportion of nitrogen dioxide must thus be 50%. Exhaust gases from diesel engines in particular usually contain a much smaller proportion of nitrogen dioxide than nitrogen monoxide. In order to increase the proportion of nitrogen dioxide, it is advisable to arrange an oxidation catalyst DOC (Diesel Oxidation Catalyst) in the exhaust line in a position upstream of the SCR catalyst. An oxidation catalyst oxidizes nitrogen monoxide NO to nitrogen dioxide NO2. Thus, the proportion of nitrogen dioxide NO2 in the exhaust gases can increase to the level at which the SCR catalyst provides an optimal shape to reduce nitrogen oxides NOx. 1 537 709 The oxidation of an oxidation catalyst to oxidize nitrogen monoxide NO to nitrogen dioxide NO2 varies with the temperature of the exhaust gases and Nide. Since the temperature and flow of the exhaust gases vary during operation of an internal combustion engine, an oxidation catalyst may not always deliver the desired distribution between the two kinds of nitrogen oxide. If an oxidation catalyst is dimensioned to oxidize nitrogen oxides in exhaust gases at an average temperature of the exhaust gases, a too low proportion of nitrogen dioxide NO2 is obtained at low exhaust temperatures and a too high proportion of nitrogen dioxide NO2 at high exhaust temperatures. A too low proportion of nitrogen dioxide NO2 results in a poor efficiency in SCR catalyst. A too high proportion of nitrogen dioxide NO2 results in nitrous oxide being formed in contact with injected urea solution. Nitrous oxide is a strong greenhouse gas.

US 7, 810, 316 visar en avgasledning hos en forbranningsmotor med komponenter for efterbehandling av avgaser. Avgasledningen innefattar i en utforingsform tva parallella ledningar som är forsedda med var sin oxidationskatalysator. Den ena oxidationskata- lysatorn anvands huvudsakligen for att oxidera kvavemonoxid till kvavedioxid vid tillfallen som forbranningsmotorn är lagt belastad och den andra oxidationskatalysatorn anvands huvudsakligen for att oxidera kvavemonoxid till kvavedioxid vid till-fallen som forbranningsmotorn är Mgt belastad. En ventil styr avgasflodet till de respektive parallella ledningarna innan det leds till en SCR-katalysator och/eller ett par- tikelfilter. US 7, 810, 316 disclose an exhaust line of an internal combustion engine with exhaust aftertreatment components. In one embodiment, the exhaust line comprises two parallel lines which are each provided with an oxidation catalyst. One oxidation catalyst is used mainly to oxidize nitrogen monoxide to nitrogen dioxide in cases where the internal combustion engine is loaded and the other oxidation catalyst is mainly used to oxidize nitrogen monoxide to nitrogen dioxide in cases where the internal combustion engine is heavily loaded. A valve controls the exhaust flow to the respective parallel lines before it is led to an SCR catalyst and / or a particulate filter.

SAMMANFATTNING AV UPPFINNINGEN Syftet med foreliggande uppfinning är att tillhandahalla ett arrangemang for efterbe- handling av avgaser fran en forbranningsmotor dar oxidation av kvavemonoxid till kvavedioxid sker i en mangd sa att avgaserna erhaller en onskad fordelning av kvavemonoxid och kvavedioxid under varierande driftsforhallanden av forbranningsmotorn. SUMMARY OF THE INVENTION The object of the present invention is to provide an arrangement for after-treatment of exhaust gases from an internal combustion engine where oxidation of nitrogen monoxide to nitrogen dioxide takes place in an amount such that the exhaust gases obtain a desired distribution of nitrogen monoxide and nitrogen dioxide under varying operating conditions of combustion engine conditions.

Detta syfte uppnas med arrangemang av det inledningsvis namnda slaget, vilket utmarks av de sardrag som anges i patentkravets 1 kannetecknande del. I detta fall anvands salcdcs en forsta oxidationskatalysator som är anordnad i en bypasslcdning till avgasledningen och en andra oxidationskatalysator som är anordnad i avgasledningen nedstroms bypassledningen. Den forsta oxidationskatalysatorn oxidationskapacitet är bcroendc av avgasernas temperatur och Nide gcnom bypasslcdningcn. Mcd hjalp av namnda styrmedel kan flodet och temperaturen hos avgaserna som leds genom den 2 537 709 forsta oxidationskatalysatorn regleras. Med kannedom om den andra oxidationskatalysatoms oxidationskapacitet kan den forsta oxidationskatalysatoms oxidationskapacitet regleras sà att den forsta oxidationskatalysatom och den andra oxidationskatalysatom tillsammans tillhandahaller en oxidation av kvavemonoxid till kvavedioxid i en mangd sâ att avgasema som lamnar den andra oxidationskatalysatom har en onskad fordelning av kvavemonoxid och kvavedioxid. Enligt uppfinningen stracker sig bypassledningen runt en turbin i avgasledningen. Darmed kan avgaser ledas till den forsta oxidationskatalysatom fran en position uppstroms turbinen. Avgasema har har ett hogre tryck och en hogre temperatur an de avgaser som leds till den andra oxidationskataly- satom som saledes är belagen nedstroms turbinen. Darmed kan den forsta oxidationskatalysatoms tillhandahalla en mycket god kompletterande oxidationskapacitet vid driftstillfallen dâ den andra oxidationskatalysatom har en relativt liten oxidationskapacitet. This object is achieved with arrangements of the kind mentioned in the introduction, which are defined by the features stated in the cantilevered part of claim 1. In this case, a first oxidation catalyst is arranged which is arranged in a bypass line to the exhaust line and a second oxidation catalyst which is arranged in the exhaust line downstream of the bypass line. The oxidation capacity of the first oxidation catalyst is determined by the temperature of the exhaust gases and by the bypass solution. With the aid of said control means, the flow and temperature of the exhaust gases passed through the first oxidation catalyst can be regulated. With knowledge of the oxidation capacity of the second oxidation catalyst, the oxidation capacity of the first oxidation catalyst can be controlled so that the first oxidation catalyst and the second oxidation catalyst together provide an oxidation of nitrogen monoxide to nitrogen dioxide in an amount such that the exhaust gases leaving the second oxidation catalyst have advantageous. According to the invention, the bypass line extends around a turbine in the exhaust line. This allows exhaust gases to be led to the first oxidation catalyst from a position upstream of the turbine. The exhaust gases have a higher pressure and a higher temperature than the exhaust gases which are led to the second oxidation catalyst which is thus coated downstream of the turbine. Thus, the first oxidation catalyst can provide a very good supplementary oxidation capacity in operational cases where the second oxidation catalyst has a relatively small oxidation capacity.

Enligt en foredragen utforingsform av fOreliggande uppfinning är den andra oxidationskatalysatom dimensionerad sâ att den sjalv har kapacitet att oxidera kvaxemonoxid till kvavedioxid i en mangd sâ att den onskade fordelningen av kvavemonoxid och kvavedioxid uppnas i avgaserna som lamnar den andra oxidationskatalysatom vid driftstillfallen dâ det rader optimala forhallanden att oxidera kvavemonoxid till kvave- dioxid. Optimala forhallanden for att oxidera kvavemonoxid till kvavedioxid fader da ett litet flOde av avgaser med en temperatur av cirka 300°C leds genom den andra oxidationskatalysatorn. Da optimala forhallanden raider leds inga avgaser genom bypassledningen och den forsta oxidationskatalysatom utan den andra oxidationskatalysatom svara for hela oxidationsprocessen. Om avgasemas temperatur sjunker och/eller avgas- flodet okar har inte den andra oxidationskatalysatorn langre kapacitet att oxidera kvavemonoxid till kvavedioxid i en mangd sa att det onskade forhallandet erhalls. I detta fall styrs en lamplig mängd avgaser genom den forsta oxidationskatalysatom sâ att den tillhandahaller en kompletterande oxidation sâ att det onskade forhallandet mellan kvaveoxid och kvavedioxid erhalls nedstroms den andra oxidationskatalysatom. According to a preferred embodiment of the present invention, the second oxidation catalyst is dimensioned so that it itself has the capacity to oxidize nitric oxide to nitrogen dioxide in an amount such that the desired distribution of nitrogen monoxide and nitrogen dioxide is achieved in the exhaust gases leaving the second oxidation catalyst at optimum conditions. to oxidize nitrogen monoxide to nitrogen dioxide. Optimal conditions for oxidizing nitrogen monoxide to nitrogen dioxide fade as a small flow of exhaust gases with a temperature of about 300 ° C is passed through the second oxidation catalyst. As optimal conditions prevail, no exhaust gases are passed through the bypass line and the first oxidation catalyst but the second oxidation catalyst is responsible for the entire oxidation process. If the exhaust gas temperature drops and / or the exhaust flow increases, the other oxidation catalyst no longer has the capacity to oxidize nitrogen monoxide to nitrogen dioxide in an amount so that the desired ratio is obtained. In this case, an appropriate amount of exhaust gases is controlled by the first oxidation catalyst so that it provides a complementary oxidation so that the desired ratio of nitrogen oxide to nitrogen dioxide is obtained downstream of the second oxidation catalyst.

Enligt en foredragen utforingsform av foreliggande uppfinning har den forsta oxidationskatalysatom en hogre halt av en adelmetallbelaggning an den andra oxidationskatalysatom. Adelmetallbelaggningar av platina, palladium och rodium kan anvandas som katalysatormaterial i oxidationskatalysatorer. Ju storre mangd adelmetall per ytenhet som oxidationskatalysatom har desto hogre oxidationskapacitet. Genom att ge den fcirsta oxidationskatalysatorn en hog halt av, exempelvis, platina kan den tillhan- 3 537 709 dahalla en mycket hog oxidationskapacitet dâ behov foreligger. Den andra oxidationskatalysatom kan ges en lagre oxidationskapacitet och damned forses med en lagre halt av platina. According to a preferred embodiment of the present invention, the first oxidation catalyst has a higher content of a noble metal coating than the second oxidation catalyst. Noble metal coatings of platinum, palladium and rhodium can be used as catalyst materials in oxidation catalysts. The larger the amount of noble metal per unit area that the oxidation catalyst has, the higher the oxidation capacity. By giving the first oxidation catalyst a high content of, for example, platinum, it can provide a very high oxidation capacity when needed. The second oxidation catalyst can be given a lower oxidation capacity and damned is provided with a lower content of platinum.

Enligt en foredragen utforingsform av foreliggande uppfinning innefattar namnda styrmedel atminstone ett ventilorgan i bypassledningen och en styrenhet som är anpassad att styra ventilorganet sâ att den forsta oxidationskatalysatom genomstrommas av en onskad andel av avgasflodet i avgasledningen. Altemativt kan ventilorganet sitta i avgasledningen vid bypassledningens inlopp eller utlopp. Ventilorganet har med fordel en utformning sa att den kan stallas i manga olika lagen sâ att flodet genom bypassled- ningen kan regleras stegvis eller steglost. According to a preferred embodiment of the present invention, said control means comprises at least one valve means in the bypass line and a control unit adapted to control the valve means so that the first oxidation catalyst is passed through by a desired proportion of the exhaust gas flow in the exhaust line. Alternatively, the valve means may be located in the exhaust line at the inlet or outlet of the bypass line. The valve member advantageously has a design so that it can be stabled in many different layers so that the flow through the bypass line can be regulated stepwise or steplessly.

Enligt en foredragen utforingsform av foreliggande uppfinning namnda styrmedel alien innefattar en avgasbroms som är anordnad i avgasledningen i en position mellan by- passledningens inlopp och utlopp. Avgasbromsen kan vara en befintlig avgasbroms i ett fordon. En avgasbroms är en ventil som är anordnad i avgasledningen. I detta fall kan styrenheten reglera avgasflodet bade genom bypassledningen och genom avgasledningen. Darmed uppkommer ett flertal mojligheter att reglera Wide och temperatur pa avgasema som leds genom bypassledningen och darmed den forsta oxidationskata- lysatom oxidationskapacitet. According to a preferred embodiment of the present invention, the control means said alien comprises an exhaust brake which is arranged in the exhaust line in a position between the inlet and the outlet of the bypass line. The exhaust brake can be an existing exhaust brake in a vehicle. An exhaust brake is a valve that is arranged in the exhaust line. In this case, the control unit can regulate the exhaust flow both through the bypass line and through the exhaust line. This gives rise to a number of possibilities for regulating the width and temperature of the exhaust gases which are led through the bypass line and thus the oxidation capacity of the first oxidation catalyst.

Enligt en foredragen utforingsform av foreliggande uppfinning innefattar namnda styrmedel atminstone en sensor som är anpassade att avkanna en parameter med vilken styrenheten uppskattar flodet och temperaturen pa avgasema som leds genom den forsta oxidationskatalysatorn. Namnda sensor kan vara en eller flera lampligt placerade temperatursensorer eller flodessensorer. Andra typer av sensorer kan sjalvfallet utnyttjas. Med kiinnedom om flOdet och temperaturen pa avgasema som leds genom avgasledningen kan den andra oxidationskatalysatoms oxidationskapacitet bestammas. Styrenheten kan darefter leda en lamplig andel av avgasflodet i avgasledningen genom bypassledningen och den fOrsta oxidationskatalysatom sâ att den Onskade fOrdelning av kvavemonoxid och kvavedioxid erhalls. According to a preferred embodiment of the present invention, said control means comprises at least one sensor which is adapted to sense a parameter with which the control unit estimates the flow and the temperature of the exhaust gases which are passed through the first oxidation catalyst. Said sensor may be one or more suitably placed temperature sensors or river sensors. Other types of sensors can of course be used. With knowledge of the flow and temperature of the exhaust gases passed through the exhaust line, the oxidation capacity of the second oxidation catalyst can be determined. The control unit can then direct a suitable proportion of the exhaust gas flow in the exhaust line through the bypass line and the first oxidation catalyst so that the desired distribution of nitrogen monoxide and nitrogen dioxide is obtained.

Enligt en foredragen utforingsform av foreliggande uppfinning är turbinen är en turbin hos ett turboaggregat eller en compoundturbin. Manga fordon drivs av overladdade forbranningsmotorer. Turbinen kan i detta fall vara en komponent hos ett turboaggre- gat som aven innefattar en kompressor for komprimering av luft som leds till forbran- 4 537 709 ningsmotom. Bypassledningen med den forsta oxidationskatalysatom kan med fordel anordnas i en avgasledning runt en sadan turbin. Bypassledningen kan utgoras av en befintlig wastegate hos turbinen. I fordon dar inloppsluften komprimeras i tva steg av en hogtrycksturbin och en lagtrycksturbin kan bypassledningen med den forsta oxidat- ionskatalysatom anordnas runt en av namnda turbiner. Hos fordon med en compoundturbin erhalls aven mOjligheten att anordna bypassledningen med den forsta oxidationskatalysatom sa att den mottar avgaser med en hog temperatur uppstroms compoundturbinen. According to a preferred embodiment of the present invention, the turbine is a turbine of a turbocharger or a compound turbine. Many vehicles are powered by overcharged internal combustion engines. The turbine can in this case be a component of a turbocharger which also comprises a compressor for compressing air which is led to the internal combustion engine. The bypass line with the first oxidation catalyst can advantageously be arranged in an exhaust line around such a turbine. The bypass line can be made up of an existing wastegate of the turbine. In vehicles where the inlet air is compressed in two stages by a high-pressure turbine and a low-pressure turbine, the bypass line with the first oxidation catalyst can be arranged around one of said turbines. In vehicles with a compound turbine, it is also possible to arrange the bypass line with the first oxidation catalyst so that it receives exhaust gases with a high temperature upstream of the compound turbine.

Enligt en foredragen utforingsform av foreliggande uppfinning innefattar arrangemanget en SCR-katalysator som är anordnad i avgasledningen i en position nedstroms den andra oxidationskatalysatom med avseende pa avgasemas avsedda stromningsriktning i avgasledningen. I en SCR-katalysator reduceras kvaveoxiderna i avgasema till kvavgas och vattenanga. Den reduktionen sker effektivast dâ kvaveoxiden innehal- ler en lika stora andel kvavemonoxid och kvavedioxid. Hos avgasema som lamnar en forbranningsmotor är andelen kvavedioxid klart lagre an andelen kvavemonoxid. Med hjalp av den forsta oxidationskatalysatom och den andra oxidationskatalysatom kan andelen kvavedioxid Okas pa bekostnad av andelen kvavemonoxid sâ att ett optimalt forhallande mellan kvavemonoxid och kvavedioxid vasentligen alltid kan uppnas un- der varierande driftsforhallanden. Arrangemanget kan i detta fall innefatta komponen- ter for tillforsel av urealosning i en position uppstroms SCR-katalysatom med avseende pa avgasemas avsedda stromningsriktning i avgasledningen. En losning av urea sprutas har in i avgasledningen. Da urealosningen forangas av de varma avgasema bildas ammoniak som leds tillsammans med avgasema genom SCR-katalysatom. Med en korrekt dosering av urea kan forbranningsmotorns utslapp av kvaveoxider i en stor utstrackning reduceras. According to a preferred embodiment of the present invention, the arrangement comprises an SCR catalyst arranged in the exhaust line in a position downstream of the second oxidation catalyst with respect to the intended direction of flow of the exhaust gases in the exhaust line. In an SCR catalyst, the nitrogen oxides in the exhaust gases are reduced to nitrogen gas and water vapor. This reduction takes place most effectively when the nitrogen oxide contains an equal proportion of nitrogen monoxide and nitrogen dioxide. In the exhaust gases that leave an internal combustion engine, the proportion of nitrogen dioxide is clearly lower than the proportion of nitrogen monoxide. With the help of the first oxidation catalyst and the second oxidation catalyst, the proportion of nitrogen dioxide can be increased at the expense of the proportion of nitrogen monoxide so that an optimal ratio between nitrogen monoxide and nitrogen dioxide can essentially always be achieved under varying operating conditions. The arrangement may in this case comprise components for supplying urea solution in a position upstream of the SCR catalyst with respect to the intended flow direction of the exhaust gases in the exhaust line. A solution of urea is sprayed into the exhaust line. As the urea solution is evaporated by the hot exhaust gases, ammonia is formed which is passed together with the exhaust gases through the SCR catalyst. With the correct dosage of urea, the emissions of nitrogen oxides from the internal combustion engine can be greatly reduced.

Enligt en foredragen utforingsform av foreliggande uppfinning innefattar arrangemanget ett partikelfilter som är anordnat i en position nedstroms den andra oxidations- katalysatom med avseende pa avgasemas avsedda strOmningsriktning i avgasledningen. I ett partikelfilter fastnar och forbranns sotpartiklar i avgasema. Avgasemas driftstemperatur är inte alltid tillracklig hog for aft kontinuerligt uppratthalla en temperatur i partikelfiltret vid vilken sotpartiklama forbranns. Sotpartiklamas forbranningstemperatur kan emellertid sankas avsevart da avgasema innehaller en hog andel kvavedioxid. According to a preferred embodiment of the present invention, the arrangement comprises a particle filter arranged in a position downstream of the second oxidation catalyst with respect to the intended direction of flow of the exhaust gases in the exhaust line. In a particle filter, soot particles get stuck and burned in the exhaust gases. The operating temperature of the exhaust gases is not always sufficiently high to continuously maintain a temperature in the particulate filter at which the soot particles are burned. However, the combustion temperature of the soot particles can be lowered considerably as the exhaust gases contain a high proportion of nitrogen dioxide.

For att sanka sotpartiklarnas antandningstemperatur kan med fordel en oxidationskata- lysator anvandas. Med en lamplig andel kvavedioxid i avgaserna kan en antandnings- 537 709 temperatur erhallas vid vilken sotpartiklama forbrannas vasentligen kontinuerligt under en forbranningsmotors varierande driftsforhallanden. Om bade ett partikelfilter och en SCR-katalysator anvands i avgasledningen placeras partikelfiltret mellan oxidationskatalysatom och SCR-katalysatom. Ett annat satt att hoja avgastemperaturen är att spruta in oforbrant bransle i en position uppstroms den forsta eller andra oxidationska- talysatorn. Darmed kan avgasernas temperatur hojas markant i oxidationskatalysatorema vilket garantera en forbranning av sotpartiklama i det nedstroms anordnade partikelfiltret. In order to lower the ignition temperature of the soot particles, an oxidation catalyst can advantageously be used. With an appropriate proportion of nitrogen dioxide in the exhaust gases, an ignition temperature can be obtained at which the soot particles are burned substantially continuously during the varying operating conditions of an internal combustion engine. If both a particulate filter and an SCR catalyst are used in the exhaust line, the particulate filter is placed between the oxidation catalyst and the SCR catalyst. Another way of raising the exhaust gas temperature is to inject unburned fuel in a position upstream of the first or second oxidation catalyst. Thus, the temperature of the exhaust gases can be significantly increased in the oxidation catalysts, which guarantees a combustion of the soot particles in the downstream particle filter.

Det inledningsvis namnda syftet uppnas aven med forfarandet som anges i patentkravets 11. The object mentioned in the introduction is also achieved by the method as stated in claim 11.

KORT BESKRIVNING AV RITNINGEN I det foljande beskrivs sasom ett exempel utfOringsformer av uppfinningen med hanvisning till bifogade ritningar, pa vilka: Fig. 1 visar ett arrangemang for behandling av avgaser fran en forbranningsmotor enligt en forsta utforingsform av uppfinning, Fig. 2 visar ett arrangemang for behandling av avgaser fran en forbranningsmotor enligt en andra utfOringsform av uppfinning och Fig. 3 visar ett arrangemang for behandling av avgaser fran en forbranningsmotor enligt en tredje utforingsform av uppfinning. BRIEF DESCRIPTION OF THE DRAWINGS The following is an exemplary embodiment of the invention with reference to the accompanying drawings, in which: Fig. 1 shows an arrangement for treating exhaust gases from an internal combustion engine according to a first embodiment of the invention, Fig. 2 shows an arrangement for treatment of exhaust gases from an internal combustion engine according to a second embodiment of the invention and Fig. 3 shows an arrangement for treating exhaust gases from an internal combustion engine according to a third embodiment of the invention.

DETALJERAD BESKRIVNING AV FOREDRAGNA UTFOR1NGSFORMER AV UPPFINNINGEN Fig. 1 visar schematiskt ett fordon 1 som drivs av en overladdad forbranningsmotor 2 som kan vara en dieselmotor. Fordonet kan vara ett tungt fordon. Avgasema frail for- branningsmotom 2 leds ut via en avgasledning 3. Avgasema som lamnar fOrbranningsmotorn 2 har ett overtryck. Avgasemas overtryck utnyttjas for att driva en turbin 4 hos ett turboaggregat. Turbinen 4 driver en kompressor 5 hos turboaggregatet. Kompressom 5 komprimerar tuft som leds in i en inloppsledning 6 for luft till forbranningsmotorn 2. Inloppsledningen 6 innefattar en laddluftkylare 7 dar den komprime- rade luften kyls innan den leds till forbranningsmotom 2 . En returledning 8 for Ater- cirkulation av avgaser stracker sig fran avgasledningen 3 och till inloppsledningen 6. 6 537 709 Returledningen 8 innefattar en EGR-kylare 9 for kylning av de atercirkulerande avgasema innan de blandas med den komprimerade luften och leds till forbranningsmotom 2. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Fig. 1 schematically shows a vehicle 1 driven by an overcharged internal combustion engine 2 which may be a diesel engine. The vehicle may be a heavy vehicle. The exhaust gases from the internal combustion engine 2 are discharged via an exhaust line 3. The exhaust gases that leave the internal combustion engine 2 have an overpressure. The overpressure of the exhaust gases is used to drive a turbine 4 of a turbocharger. The turbine 4 drives a compressor 5 of the turbocharger. The compressor 5 compresses tuft which is led into an inlet line 6 for air to the internal combustion engine 2. The inlet line 6 comprises a charge air cooler 7 where the compressed air is cooled before it is led to the internal combustion engine 2. An exhaust line 8 for recirculation of exhaust gases extends from the exhaust line 3 and to the inlet line 6. The return line 8 comprises an EGR cooler 9 for cooling the recirculating exhaust gases before they are mixed with the compressed air and led to the internal combustion engine 2.

Turbinen 4 är forsedd med en s.k. wastgate som innefattar en avgaspassage 10 med en wastegate-ventil 11 med vilken det är mojligt att leda en del av avgasema fOrbi turbinen 4. En wastegate-ventil 11 oppnas normalt da turboaggregatets laddtryck blir for hogt. Avgasledningen 3 innefattar i detta fall en andra turbin i form av en compoundturbin 12 som är belagen nedstrOms turbo aggregatets turbin 4. En compoundturbin 12 utnyttjas for att utvinna energi ur avgasema for drift av fordonet. En avgasbroms 13 är anordnad i avgasledningen 3 nedstroms compoundturbinen 12. Avgasbromsen 13 är en ventil i form av ett spj all i avgasledningen 3 med vilket det är mojligt att vasentligen steglost reglera avgasflodet i avgasledningen 3. Avgasledningen 3 är forsedd med en bypassledning 14. Bypassledningen 14 innefattar ett inlopp 14a dar avgaser fran avgas- ledningen 3 mottas i en position uppstrOms compoundturbinen 12 och avgasbromsen 13. Bypassledningen 14 innefattar ett utlopp 14b dar avgaser leds tillbaka till avgas- ledningen 3 i en position nedstroms compoundturbinen 12 och avgasbromsen 13. The turbine 4 is equipped with a so-called wastgate which comprises an exhaust passage 10 with a wastegate valve 11 with which it is possible to lead a part of the exhaust gases past the turbine 4. A wastegate valve 11 is normally opened when the charge pressure of the turbocharger becomes too high. The exhaust line 3 in this case comprises a second turbine in the form of a compound turbine 12 which is located downstream of the turbine 4 of the turbo unit. A compound turbine 12 is used to extract energy from the exhaust gases for operation of the vehicle. An exhaust brake 13 is arranged in the exhaust line 3 downstream of the compound turbine 12. The exhaust brake 13 is a valve in the form of a throttle in the exhaust line 3 with which it is possible to substantially steplessly regulate the exhaust flow in the exhaust line 3. The exhaust line 3 is provided with a bypass line 14. 14 comprises an inlet 14a where exhaust gases from the exhaust line 3 are received in a position upstream of the compound turbine 12 and the exhaust brake 13. The bypass line 14 comprises an outlet 14b where exhaust gases are led back to the exhaust line 3 in a position downstream of the compound turbine 12 and the exhaust brake 13.

Bypassledningen 14 innefattar en forsta oxidationskatalysator 15. En oxidationskataly- sator har formagan att oxidera kvavemonoxid NO till kvavedioxid NO2. En oxidationskatalysatoms formaga att oxidera kvavemonoxid till kvavedioxid är beroende av flera parametrar. En sadan parameter är avgasemas temperatur. DA avgasema har en hog temperatur erhafts en effektivare oxidering an da avgasema har en lagre temperatur. En optimal oxideringskapacitet erhalls vid cirka 300°C. En annan parameter är flodet av avgaser genom oxidationskatalysatom. Vid ett stort avgasflode kan en mindre del av kvavemonoxiden i avgasema oxideras till kvavedioxid an vid ett mindre avgasaide. En tredje parameter är halten av adelmetall i oxidationskatalysatom. Oxidationskatalysatom kan innehalla adelmetallbelaggningar av platina, palladium eller rodium. En belaggning med en hog halt av en adelmetall resulterar i en effektivare oxid- ationsprocess an en belaggning med en lagre halt av adelmetallen. Bypassledningen 14 är aven forsedd med ett ventilorgan 16. Med hjalp av ventilorganet 16 kan avgasflodet genom bypassledningen 14 styras. Endast de avgaser i avgasledningen 3 som leds in i bypassledningen 14 passerar slledes genom den forsta oxidationskatalysatom 15. The bypass line 14 comprises a first oxidation catalyst 15. An oxidation catalyst has the ability to oxidize nitrogen monoxide NO to nitrogen dioxide NO2. The ability of an oxidation catalyst to oxidize nitrogen monoxide to nitrogen dioxide depends on several parameters. One such parameter is the temperature of the exhaust gases. Since the exhaust gases have a high temperature, a more efficient oxidation is obtained than when the exhaust gases have a lower temperature. An optimum oxidation capacity is obtained at about 300 ° C. Another parameter is the flow of exhaust gases through the oxidation catalyst. With a large exhaust gas flow, a smaller part of the nitrogen monoxide in the exhaust gases can be oxidized to nitrogen dioxide than with a smaller exhaust gas. A third parameter is the content of noble metal in the oxidation catalyst. The oxidation catalyst may contain platinum, palladium or rhodium noble metal coatings. A coating with a high content of a noble metal results in a more efficient oxidation process than a coating with a lower content of the noble metal. The bypass line 14 is also provided with a valve means 16. With the aid of the valve means 16, the exhaust gas flow through the bypass line 14 can be controlled. Thus, only the exhaust gases in the exhaust line 3 which are led into the bypass line 14 pass through the first oxidation catalyst 15.

En styrenhet 17 är anpassad att styra wastegate-ventilen 11, avgasbromsen 13 och ven- tilorganet 16. Styrenheten 17 mottar information fran ett antal sensorer 18 som avkan- 7 537 709 ner parametrar med vilka avgasernas temperatur och Wide kan bestammas. Sensorerna 18 kan avkanna avgasernas temperatur, Wide, tryck pa ett lampligt antal stallen i avgasledningen 3 och bypassledningen 14. Styrenheten 17 kan aven motta information fran sensorer 18 som avkanner halten av kvaveoxid, kvavedioxid eller lustgas pa lamp- liga stallen i avgasledningen 3. Styrenheten 17 kan vara en datorenhet med en for detta andamal lamplig programvara. Avgasledningen 3 innefattar en andra oxidationskatalysator 19 som är anordnad i avgasledningen 3 i en position nedstroms bypassledningens utlopp 14b. Alla avgaser i avgasledningen 3 leds armed genom den andra oxidationskatalysatorn 19. A control unit 17 is adapted to control the wastegate valve 11, the exhaust brake 13 and the valve means 16. The control unit 17 receives information from a number of sensors 18 which sense parameters with which the temperature and Wide of the exhaust gases can be determined. The sensors 18 can detect the temperature of the exhaust gases, Wide, pressure on an appropriate number of stalls in the exhaust line 3 and the bypass line 14. The control unit 17 can also receive information from sensors 18 which detect the content of nitrogen oxide, nitrogen dioxide or nitrous oxide in the suitable stalls in the exhaust line 3. 17 may be a computer unit with software suitable for this purpose. The exhaust line 3 comprises a second oxidation catalyst 19 which is arranged in the exhaust line 3 in a position downstream of the bypass line 14b of the bypass line. All exhaust gases in the exhaust line 3 are passed armed through the second oxidation catalyst 19.

Ett partikelfilter 20 är anordnat nedstroms den andra oxidationskatalysatorn 19. Parti- kelfiltret 20 uppgift är att fanga upp sotpartiklarna i avgaserna. Sotpartiklarna forbranns darefter i partikelfiltret 20. Ett satt att garantera en god forbranning av sotpartiklarna i partikelfiltret är att leda avgaser med en hog halt av kvavedioxid genom partikelfiltret. En riklig forekomst av kvavedioxid i avgaserna sinker sotpartiklarnas for- branningstemperatur. Med hjalp av den forsta oxidationskatalysatorn 15 och den andra oxidationskatalysatorn 19 kan avgaserna forses med kvavedioxid i en mangd sâ att forbranningstemperaturen sinks till en temperaturnivâ som uppratthalls i partikelfiltret under normal drift av forbranningsmotorn. Darmed kan sotpartiklarna forbrannas vasentligen kontinuerligt i partikelfiltret. I detta fall är aven en anordning 21 for tillforsel av oforbrant bransle HC i bypassledningen 14 anordnad i en position uppstroms den forsta oxidationskatalysatorn 15. Genom att vid lamp liga tillfällen spruta in oforbrant bransle kan avgasernas temperatur hojas vasentligt i den forsta oxidationskatalysatorn 15 och armed i det nedstroms anordnade partikelfiltret 20 sâ att sotpartiklarna med sakerhet forbranns. A particulate filter 20 is arranged downstream of the second oxidation catalyst 19. The task of the particulate filter 20 is to capture the soot particles in the exhaust gases. The soot particles are then incinerated in the particle filter 20. One way of guaranteeing a good combustion of the soot particles in the particle filter is to lead exhaust gases with a high content of nitrogen dioxide through the particle filter. An abundant presence of nitrogen dioxide in the exhaust gases lowers the combustion temperature of the soot particles. With the aid of the first oxidation catalyst 15 and the second oxidation catalyst 19, the exhaust gases can be supplied with nitrogen dioxide in an amount such that the combustion temperature is lowered to a temperature level maintained in the particulate filter during normal operation of the internal combustion engine. Thus, the soot particles can be burned substantially continuously in the particle filter. In this case also a device 21 for supplying unburned fuel HC in the bypass line 14 is arranged in a position upstream of the first oxidation catalyst 15. By injecting unburned fuel on occasional occasions, the exhaust gas temperature can be substantially increased in the first oxidation catalyst 15 and armed in the downstream particle filter 20 so that the soot particles are safely burned.

Avgasledningen är forsedd med en SCR-katalysator 23 for katalytisk avgasrening enligt den metod som benamns SCR (Selective Catalytic Reduction). Denna metod innebar att en urealosning sprutas in i avgaserna. Urealosning kan lagras i en tank och leds, via en ledning, till ett insprutningsorgan 22 som sprutar in urealosningen i avgasled- ningen. Styrenheten 17 eller en annan separat styrenhet kan styra tillfOrseln av urea- losningen. En sa.dan styrenhet kan med information avseende specifika motorparametrar berakna den mangd av urealosningen som behover tillsittas for att kvaveoxiden i avgaserna ska reduceras pa ett optimalt sat. Den tillfOrda urealOsningen upphettas av avgaserna i avgasledningen sâ att den forangas och omvandlas till ammoniak. Bland- ningen av ammoniak och avgaserna leds darefter till SCR-katalysatorn 23 . I SCR- 8 537 709 katalysatorn 23 reagerar kvavet hos kvaveoxiderna i avgasema med kvavet i ammoniaken sa att kvavgas bildas. Syret hos kvaveoxiderna reagerar med valet i ammoniaken sa att vatten bildas. Kvaveoxiderna i avgasema reduceras saledes i SCR-katalysatom 23 till kvavgas och vattenanga. Kvaveoxiderna NOx i avgasema bestar av kvavemonoxid NO och kvavedioxid NO2. En SCR-katalysator 23 reducerar mangden kvaveoxider i avgasema pa ett optimalt satt da avgasema som leds genom SCRkatalysatorn 23 har en lika stor mangd kvavemonoxid som kvavedioxid. En SCRkatalysator reducerar saledes kvaveoxider optimalt dâ andelen kvavedioxid är 50 % av den totala mangden kvaveoxider. Avgaser fran forbranningsmotorer innehaller i regel en betydligt stone andel kvavemonoxid an kvavedioxid. The exhaust line is equipped with an SCR catalyst 23 for catalytic exhaust purification according to the method called SCR (Selective Catalytic Reduction). This method meant that a urea solution was injected into the exhaust gases. Urea discharge can be stored in a tank and is led, via a line, to an injection means 22 which injects the urea discharge into the exhaust line. The control unit 17 or another separate control unit can control the supply of the urea solution. Such a control unit can, with information regarding specific engine parameters, calculate the amount of urea solution that needs to be added in order for the nitrogen oxide in the exhaust gases to be reduced in an optimal way. The supplied urea solution is heated by the exhaust gases in the exhaust line so that it evaporates and is converted into ammonia. The mixture of ammonia and the exhaust gases is then passed to the SCR catalyst 23. In the SCR 8 537 709 catalyst 23, the nitrogen of the nitrogen oxides in the exhaust gases reacts with the nitrogen in the ammonia so that nitrogen gas is formed. The oxygen of the nitrogen oxides reacts with the choice in the ammonia so that water is formed. The nitrogen oxides in the exhaust gases are thus reduced in the SCR catalyst 23 to nitrogen gas and water vapor. The nitrogen oxides NOx in the exhaust gases consist of nitrogen monoxide NO and nitrogen dioxide NO2. An SCR catalyst 23 reduces the amount of nitrogen oxides in the exhaust gases in an optimal way as the exhaust gases passed through the SCR catalyst 23 have as large an amount of nitrogen monoxide as nitrogen dioxide. An SCR catalyst thus reduces nitrogen oxides optimally when the proportion of nitrogen dioxide is 50% of the total amount of nitrogen oxides. Exhaust gases from internal combustion engines generally contain a significant amount of nitrogen monoxide than nitrogen dioxide.

Att hOja andelen kvavedioxid i avgasema är saledes viktigt bade for att tillhandahalla en vasentligen kontinuerlig forbranning av sotpartiklarna i partikelfiltret 20 och for att reducera kvaveoxiderna i avgasema i SCR-katalysatom 23. Avgasledningen innefattar aven en ammoniak-katalysator 24 dar ett eventuellt overskott pa ammoniak och kvavedioxid omvandlas till kvavgas och lustgas. Lustgas är en kraftig vaxthusgas som i mojligaste man bar forhindras att ledas ut till omgivningen. Det är saledes viktigt att oxidationskatalysatorerna 15, 19 vasentligen alltid kan oxidera kvavemonoxid till kvavedioxid i en mangd sâ att kvaveoxiden som nar SCR-katalysatorn 23 innehaller lika mycket kvavedioxid NO2 som kvavemonoxid NO. Increasing the proportion of nitrogen dioxide in the exhaust gases is thus important both to provide a substantially continuous combustion of the soot particles in the particulate filter 20 and to reduce the nitrogen oxides in the exhaust gases in the SCR catalyst 23. The exhaust line also includes an ammonia catalyst 24 where any ammonia and nitrogen dioxide is converted to nitrogen gas and nitrous oxide. Nitrous oxide is a powerful greenhouse gas that should as far as possible be prevented from being led out to the environment. It is thus important that the oxidation catalysts 15, 19 can essentially always oxidize nitrogen monoxide to nitrogen dioxide in an amount such that the nitrogen oxide near the SCR catalyst 23 contains as much nitrogen dioxide NO2 as nitrogen monoxide NO.

Under drift av forbranningsmotom 2 leds avgaserna ut genom avgasledningen 3. Styrenheten 17 mottar vasentligen kontinuerligt information fran sensorema 18 avseende avgasemas temperatur, tryck, flOde etc. Med hjalp av denna information och informat- ion avseende forbranningsmotorns 2 varvtal och belastning bestammer styrenheten 17 med hjalp av mappar eller annan typ av lagrad information hur stor del av kviivemonoxiden i avgasemas som behOver oxiderar till kviivedioxid for att avgasema som leds till SCR-katalysatom 23, ska innehalla lika mycket kvavemonoxid NO och kvavedioxid NO,. During operation of the internal combustion engine 2, the exhaust gases are led out through the exhaust line 3. The control unit 17 essentially continuously receives information from the sensors 18 regarding the exhaust gas temperature, pressure, flow, etc. With the help of this information and information regarding the combustion engine 2 speed and load, the control unit 17 determines of folders or other type of stored information how much of the nitrogen monoxide in the exhaust gases that need to oxidize to nitrogen dioxide in order for the exhaust gases led to the SCR catalyst 23 to contain the same amount of nitrogen monoxide NO and nitrogen dioxide NO.

Den andra oxidationskatalysatom 19 ar dimensionerad sa att den sjalv kan oxidera kvavemonoxid NO till kvavedioxid NO2 i en mangd sa att lika mycket kvavemonoxid NO och kvavedioxid NO2 leds till SCR-katalysatom 23 da avgasema har en temperatur av cirka 300°C och avgasflodet är Mgt. Under Adana optimala driftstillfallen ticker det att avgasema endast leds genom den andra oxidationskatalysatom 19. Da styrenheten 17 mottar information fran, bl.a. namnda sensorer 18 som indikerar att det rader ett 9 537 709 sadant optimalt driftstillstand stanger den ventilorganet 16. Darmed leds inga avgaser genom bypassledningen 14 och den forsta oxidationskatalysatom 15. Den andra oxidationskatalysatom svarar har sjalv for oxidationen av kvWemonoxid NO till kvWedioxid NO2. The second oxidation catalyst 19 is dimensioned so that it itself can oxidize nitrogen monoxide NO to nitrogen dioxide NO2 in an amount such that as much nitrogen monoxide NO and nitrogen dioxide NO2 are conducted to the SCR catalyst 23 when the exhaust gases have a temperature of about 300 ° C and the exhaust gas flow is Mgt. During Adana's optimal operating conditions, it ticks that the exhaust gases are only passed through the second oxidation catalyst 19. When the control unit 17 receives information from, e.g. said sensors 18 which indicate that it radiates such an optimal operating condition, it closes the valve means 16. Thereby no exhaust gases are passed through the bypass line 14 and the first oxidation catalyst 15. The second oxidation catalyst is responsible for the oxidation of kvWmonoxide NO to kvWedioxide NO2.

Om avgasemas temperatur sjunker till ett lagre varde och/eller att avgasflodet genom avgasledningen iikar kan konstateras att den andra oxidationskatalysatom 19 inte sjalv har kapacitet att oxidera kvWemonoxid till kvWedioxid i en omfattning s'a att lika mycket kvavemonoxid NO och kvavedioxid NO2 leds till SCR-katalysatom 23. Da styrenheten 17 mottar information som indikerar att sâ är fallet uppskattar den hur stor andel av avgasema i avgasledningen 3 som behover ledas genom bypassledningen 14 och den fOrsta oxidationskatalysatom 15 for att en lika stor andel kvavemonoxid NO och kvavedioxid NO2 ska ledas till SCR-katalysatom 23. Eftersom bypassledningen 14 har ett inlopp 14a i en position uppstroms compoundturbin 12 kan avgaser med ett hOgre tryck och en hogre temperatur mottas i den fOrsta oxidationskatalysatom 15 an i den andra oxidationskatalysatom 19. Oxidationen av kvavemonoxid NO till kvavedioxid NO2 blir darmed effektivare i den fcirsta oxidationskatalysatom 15 an i den andra oxidationskatalysatom 19. For att den fOrsta oxidationskatalysatom 15 ska erhalla en ytterligare forhojd oxidationskapacitet kan den innehalla en hogre halt av adelmetall an den andra oxidationskatalysatom 19. If the temperature of the exhaust gases drops to a lower value and / or the exhaust gas flow through the exhaust line is found, it can be stated that the second oxidation catalyst 19 itself does not have the capacity to oxidize carbon monoxide to carbon dioxide to an extent such that equal nitrogen monoxide NO and nitrogen dioxide NO2 are conducted to SCR. catalyst 23. As the control unit 17 receives information indicating that this is the case, it estimates the proportion of the exhaust gases in the exhaust line 3 that need to be passed through the bypass line 14 and the first oxidation catalyst 15 in order for an equal proportion of nitrogen monoxide NO and nitrogen dioxide NO2 to be passed to SCR The catalyst 23. Since the bypass line 14 has an inlet 14a in a position upstream of the compound turbine 12, exhaust gases with a higher pressure and a higher temperature can be received in the first oxidation catalyst 15 than in the second oxidation catalyst 19. The oxidation of nitrogen monoxide NO to nitrogen dioxide NO2 thus becomes more efficient. in the first oxidation catalyst 15 an in the second o oxidation catalyst 19. In order for the first oxidation catalyst 15 to have a further increased oxidation capacity, it may contain a higher content of noble metal than the second oxidation catalyst 19.

Den fOrsta oxidationskatalysatom 15 tillhandahafter damned en hog oxidationskapacitet sâ att den Wen vid ogynnsamma driftstillfällen, dâ avgasema har en lag temperatur och avgasflodet är Mgt, har formaga att tillsammans med den andra oxidations- katalysatom 19 vasentligen alltid kunna leverera den onskade sammansattningen av kvWeoxider till SCR-katalysatom 23. Den fOrsta oxidationskatalysatom 15 kan sale-des tillhandahalla en varierbar oxidationskapacitet inom ett relativt stort omrade. Under vissa driftstillfallen kan styrenheten 17 leda hela avgasstrommen genom bypassledningen 14 och den fOrsta oxidationskatalysatorn 3. Under de fiesta driftstillfallen leds dock en del av avgasema genom bypassledningen 14 medan en resterande del leds, via den ordinarie avgasledningen 3, till compoundturbinen 12. Styrenheten 17 har med fordel kapacitet att styra ventilorganet 16 till mer eller mindre Cippna lagen sâ att avgasflodet genom bypassledningen 14 kan regleras steglost eller i ett relativt stort antal fast steg. 537 709 Styrenheten 17 kan reglera avgasernas temperatur och Wide till den forsta oxidationskatalysatorn 15 pa flera olika sat. Vid tillfdllen dâ avgasflodet genom den forsta oxidationskatalysatorn 15 ska optimeras stanger styrenheten 17 avgasbromsen 13 och Oppnar ventilorganet 16 maximalt sa att hela avgasflodet leds genom den forsta oxidat- ionskatalysatorn 15. I detta fall erhaller den uppstroms anordnade turbinen 4 aven en okad kapacitet sa att den aven genererar ett hOgre avgasflOde. Vid tillfállen da avgastemperaturen ska hojas oppnar styrenheten 17 wastegate-ventilen 11 sa att varma avgaser som inte expanderat genom turbinen 4 leds in i bypassledningen 14 och den forsta oxidationskatalysator 15. Bypassledningen 14 stacker sig runt compoundturbi- nen 12 och avgasbromsen 13. Styrenheten 17 kan darmed utnyttja avgasbromsen 13 i avgasledningen 3 och ventilorganet 16 i bypassledningen 14 for att Oka avgaserna mottryck och armed paverka temperaturen pa avgaserna som leds genom den forsta oxidationskatalysatorn 15. The first oxidation catalyst 15 provides a high oxidation capacity so that at unfavorable operating times, when the exhaust gases have a low temperature and the exhaust flow is Mgt, it is able to substantially always supply the desired composition of nitrogen oxides to SCR together with the second oxidation catalyst 19. The catalyst 23. The first oxidation catalyst 15 can thus be provided to provide a variable oxidation capacity over a relatively wide range. During certain operating cases, the control unit 17 can lead the entire exhaust stream through the bypass line 14 and the first oxidation catalyst 3. During most operating cases, however, part of the exhaust gases is led through the bypass line 14 while a remaining part is led, via the ordinary exhaust line 3, to the compound turbine 12. The control unit 17 has advantageously capacity to control the valve member 16 to more or less the Cipna law so that the exhaust flow through the bypass line 14 can be regulated steplessly or in a relatively large number of fixed steps. 537 709 The control unit 17 can control the exhaust gas temperature and Wide to the first oxidation catalyst 15 in several different ways. In the event that the exhaust flow through the first oxidation catalyst 15 is to be optimized, the control unit 17 adjusts the exhaust brake 13 and opens the valve means 16 maximally so that the entire exhaust flow is passed through the first oxidation catalyst 15. In this case the upstream turbine 4 also has an increased capacity. also generates a higher exhaust flow. In cases where the exhaust temperature is to be raised, the control unit 17 opens the wastegate valve 11 so that hot exhaust gases that have not expanded through the turbine 4 are led into the bypass line 14 and the first oxidation catalyst 15. The bypass line 14 extends around the compound turbine 12 and the exhaust brake 13. The control unit 17 can thereby utilizing the exhaust brake 13 in the exhaust line 3 and the valve means 16 in the bypass line 14 to increase the exhaust gas back pressure and armed to influence the temperature of the exhaust gases passed through the first oxidation catalyst 15.

Fig. 2 visar en forbranningsmotor 2 med en avgasledning 3 som till stora delar är ut- rustad med samma komponenter som i Fig. 1. Vi gör darfor inte nagon ytterligare genomgang av de gemensamma komponenterna. En skillnad är att avgasledningen 3 inte innefattar flagon compoundturbin 12. Bypassledningen 14 stacker sig har istallet runt en turbin 4 hos turboaggregatet. Bypassledningen 14 har har ett inlopp 14a som är be- laget uppstroms turbinen 4 och ett utlopp som är belaget nedstroms turbinen 4. Bypassledningen 14 innefattar en forsta oxidationskatalysator 15 och ett ventilorgan 16 med vilket avgasflodet genom bypassledningen kan justeras. Bypassledningen 14 kan har utgora en separat enhet eller utgora en del av en befintlig wastegate och ventilorganet 16 av en wastegate-ventil 11. Fig. 2 shows an internal combustion engine 2 with an exhaust line 3 which is largely equipped with the same components as in Fig. 1. We therefore do not make any further review of the common components. One difference is that the exhaust line 3 does not include the flake compound turbine 12. The bypass line 14 is stacked instead of around a turbine 4 of the turbocharger. The bypass line 14 has an inlet 14a which is located upstream of the turbine 4 and an outlet which is located downstream of the turbine 4. The bypass line 14 comprises a first oxidation catalyst 15 and a valve means 16 with which the exhaust flow through the bypass line can be adjusted. The bypass line 14 may have formed a separate unit or formed part of an existing wastegate and the valve means 16 of a wastegate valve 11.

Fig. 3 visar en forbranningsmotor med en avgasledning 3 som till stora delar är forsedd med samma komponenter som i Fig. 1 och 2. Vi gar dad& inte heller har flagon ytterligare genomgang av de gemensamma komponenterna. Forbranningsmotorn 2 är i detta fall en tvastegsoverladdad motor. Luften som leds till forbranningsmotorn 2 komprimeras i tvâ steg av en lagtryckskompressor 26 och en hogtryckskompressor kompressorer 5. En hogtrycksturbin 4 driver hogtryckskompressorn 5 och en lagtrycksturbin 27 driver lagtryckskompressorn 26. Avgasledningen 3 innefattar i detta fall inte heller flagon compoundturbin 12. Bypassledningen 14 stacker sig har runt lagtrycksturbinen 27 hos turboaggregatet. Bypassledningen 14 har har ett inlopp 14a som är belaget uppstroms lagtryeksturbinen 27 och ett utlopp som är belaget nedstroms lagt- 1 1 537 709 rycksturbinen 27. Bypassledningen 14 innefattar en forsta oxidationskatalysator 15 och ett ventilorgan 16. Fig. 3 shows an internal combustion engine with an exhaust line 3 which is largely provided with the same components as in Figs. 1 and 2. We do not have a further inspection of the common components either. The internal combustion engine 2 is in this case a two-stage supercharged engine. The air led to the internal combustion engine 2 is compressed in two stages by a low-pressure compressor 26 and a high-pressure compressor 5. A high-pressure turbine 4 drives the high-pressure compressor 5 and a low-pressure turbine 27 drives the low-pressure compressor 26. In this case the exhaust line 3 does not include has around the low pressure turbine 27 of the turbocharger. The bypass line 14 has an inlet 14a which is coated upstream of the low pressure turbine 27 and an outlet which is coated downstream of the pressure turbine 27. The bypass line 14 comprises a first oxidation catalyst 15 and a valve means 16.

Uppfinningen är inte begransad till den ovan beskrivna utforingsformen utan den kan varieras fritt Mom patentkravens ramar. 12 The invention is not limited to the embodiment described above, but it can be varied freely within the scope of the patent claims. 12

Claims (10)

537 709 Patentkrav537 709 Patent claims 1. Arrangemang for behandling av avgaser fran en forbranningsmotor (2), varvid arrangemanget innefattar en avgasledning (3) som leder ut avgasema fran forbrannings- motom (2), en turbin (4, 12, 27) med vilken energi utvinns ur avgasema i avgasledning (3), en bypassledning (14) som innefattar ett inlopp (14a) dar avgaser mottas fran avgasledningen (3) i en position uppstroms turbinen (4, 12, 27) och ett utlopp (14b) dar avgaser leds tillbaka till avgasledningen (3) i en position nedstroms turbinen (4, 12, 27), en forsta oxidationskatalysator (15) och en andra oxidationskatalysator (19) vilka är anpassade att oxidera kvavemonoxid till kvavedioxid i avgasledningen (3), kanne- tecknat av att den forsta oxidationskatalysator (15) är anordnad i bypassledningen (14) och den andra oxidationskatalysatom (19) är anordnad i avgasledningen (3) i en position nedstroms bypassledningen utlopp (14b) och att arrangemanget innefattar styrmedel (11, 13, 16, 17) som är anpassat att reglera Wide och/eller temperaturen pa avgaser som leds genom den forsta oxidationskatalysatom (15) i bypassledningen (14) sa att den forsta oxidationskatalysatom (15) och den andra oxidationskatalysatom (19) tillsammans tillhandahaller en oxidation av kvavemonoxid (NO) till kvavedioxid (NO2) i en mangd sâ att avgasema som lamnar den andra oxidationskatalysatom (19) har en onskad fordelning av kvavemonoxid (NO) och kvavedioxid (NO2).An arrangement for treating exhaust gases from an internal combustion engine (2), the arrangement comprising an exhaust line (3) discharging the exhaust gases from the internal combustion engine (2), a turbine (4, 12, 27) with which energy is recovered from the exhaust gases in exhaust line (3), a bypass line (14) comprising an inlet (14a) where exhaust gases are received from the exhaust line (3) in a position upstream of the turbine (4, 12, 27) and an outlet (14b) where exhaust gases are returned to the exhaust line ( 3) in a position downstream of the turbine (4, 12, 27), a first oxidation catalyst (15) and a second oxidation catalyst (19) which are adapted to oxidize nitrogen monoxide to nitrogen dioxide in the exhaust line (3), characterized in that the first oxidation catalyst (15) is arranged in the bypass line (14) and the second oxidation catalyst (19) is arranged in the exhaust line (3) in a position downstream of the bypass line outlet (14b) and that the arrangement comprises control means (11, 13, 16, 17) which is adapted to regulate Wide and / or the temperature of exhaust gases passed through the first oxidation catalyst (15) in the bypass line (14) so that the first oxidation catalyst (15) and the second oxidation catalyst (19) together provide an oxidation of nitrogen monoxide (NO) to nitrogen dioxide (NO2) in an amount so that the exhaust gases leaving the second oxidation catalyst (19) have a desired distribution of nitrogen monoxide (NO) and nitrogen dioxide (NO2). 2. Arrangemang enligt krav 1, kannetecknat av att den andra oxidationskatalysatom (19) är dimensionerad sâ att den sjalv har kapacitet att oxidera kvavemonoxid (NO) till kvavedioxid (NO2) i en mangd sa att den onskade fordelningen av kvavemonoxid (NO) och kvavedioxid (NO2) uppnas i avgasema som lamnar den andra oxidationska- talysatom vid driftstillfallen som optimala forhallanden rader for att oxidera kvavemonoxid (NO) till kvavedioxid (NO2).Arrangement according to claim 1, characterized in that the second oxidation catalyst (19) is dimensioned so that it itself has the capacity to oxidize nitrogen monoxide (NO) to nitrogen dioxide (NO2) in an amount such that the desired distribution of nitrogen monoxide (NO) and nitrogen dioxide (NO2) is obtained in the exhaust gases which leave the second oxidation catalyst in the event of operation as optimal conditions for oxidizing nitrogen monoxide (NO) to nitrogen dioxide (NO2). 3. Arrangemang enligt nagot krav 1 eller 2, kannetecknat av att den forsta oxidationskatalysatom (15) har en hogre halt av en adelmetallbelaggning an den andra oxidat- ionskatalysatom (19).An arrangement according to any one of claims 1 or 2, characterized in that the first oxidation catalyst (15) has a higher content of a noble metal coating than the second oxidation catalyst (19). 4. Arrangemang enligt nagot av foregaende krav, kannetecknat av att namnda styrmedel innefattar atminstone ett ventilorgan (16) i bypassledningen (14) och en styrenhet (17) som är anpassad att styra ventilorganet (16) sa att den forsta oxidationskatalysa35 tom (15) genomstrommas av en onskad andel av avgasflodet i avgasledningen (3). 13 537 709Arrangement according to any one of the preceding claims, characterized in that said control means comprises at least one valve means (16) in the bypass line (14) and a control unit (17) adapted to control the valve means (16) so that the first oxidation catalyst (15) is traversed by a desired proportion of the exhaust flow in the exhaust line (3). 13 537 709 5. Arrangemang enligt krav 4, kannetecknat av att namnda styrmedel aven innefattar en avgasbroms (13) som är anordnad i avgasledningen i en position mellan bypassledningens inlopp (14a) och utlopp (14b).Arrangement according to claim 4, characterized in that said control means also comprises an exhaust brake (13) which is arranged in the exhaust line in a position between the inlet (14a) of the bypass line and the outlet (14b). 6. Arrangemang enligt krav 4 eller 5, kannetecknat av att namnda styrmedel innefattar atminstone en sensor (18) som är anpassade att avkanna en parameter med vilken styrenheten (17) uppskattar flodet och temperaturen pa avgaserna som leds genom den forsta oxidationskatalysatorn (15) .Arrangement according to claim 4 or 5, characterized in that said control means comprises at least one sensor (18) adapted to sense a parameter with which the control unit (17) estimates the flow and temperature of the exhaust gases passed through the first oxidation catalyst (15). 7. Arrangemang enligt nagot av foregaende krav, kannetecknat av att turbinen är en turbin (4, 27) hos ett turboaggregat eller en compoundturbin (12).Arrangement according to one of the preceding claims, characterized in that the turbine is a turbine (4, 27) of a turbocharger or a compound turbine (12). 8. Arrangemang enligt nagot av foregaende krav, kannetecknat av att arrangemanget innefattar en SCR-katalysator (23) som är anordnad i avgasledningen (3) en position nedstroms den andra oxidationskatalysatorn (19) med avseende pa avgasernas avsedda stromningsriktning i avgasledningen (3).Arrangement according to any one of the preceding claims, characterized in that the arrangement comprises an SCR catalyst (23) arranged in the exhaust line (3) in a position below the second oxidation catalyst (19) with respect to the intended flow direction of the exhaust gases in the exhaust line (3). 9. Arrangemang enligt nagot av foregaende krav, kannetecknat av att arrangemanget innefattar ett partikelfilter (20) som är anordnat i en position nedstroms den andra ox- idationskatalysatorn (19) med avseende pa avgasernas avsedda stromningsriktning i avgasledningen (3).An arrangement according to any one of the preceding claims, characterized in that the arrangement comprises a particle filter (20) arranged in a position downstream of the second oxidation catalyst (19) with respect to the intended flow direction of the exhaust gases in the exhaust line (3). 10. Rirfarande fOr behandling av avgaser fran en forbranningsmotor (2), varvid fOr- branningsmotorn (2) är forbunden med en avgasledning (3) som innefattar en turbin (4, 12, 27) med vilken energi utvinns ur avgaserna i avgasledning (3), en bypassledning (14) som innefattar ett inlopp (14a) dar avgaser mottas frau avgasledningen (3) i en position uppstroms turbinen (4, 12, 27) och ett utlopp (14b) dar avgaser leds tillbaka till avgasledningen (3) i en position nedstroms turbinen (4, 12, 27), en forsta oxidat- ionskatalysator (15) och en andra oxidationskatalysator (19) vilka är anpassade att oxi- dera kvavemonoxid till kvavedioxid i avgasledningen (3), kannetecknat av stegen att anordna den forsta oxidationskatalysator (15) i bypassledningen (14), att anordna den andra oxidationskatalysatorn (19) i avgasledningen (3) i en position nedstroms bypassledningen utlopp (14b) och att reglera flode och/eller temperaturen pa avgaser som leds genom den forsta oxidationskatalysatorn (15) i bypassledningen (14) sâ att den forsta oxidationskatalysatorn (15) och den andra oxidationskatalysatorn (19) tillsam- 1 4 537 709 mans tillhandahaller en oxidation av kvavemonoxid (NO) till kvavedioxid (NO2) i en mangd sa aft avgasema som lamnar den andra oxidationskatalysatom (19) har en onskad fOrdelning av kvavemonoxid (NO) och kvavedioxid (NO2). 21 14 14a 11 2 537 709 1 12 18 16 18 \ 14b --- _-----24A process for treating exhaust gases from an internal combustion engine (2), wherein the internal combustion engine (2) is connected to an exhaust line (3) comprising a turbine (4, 12, 27) with which energy is recovered from the exhaust gases in the exhaust line (3). ), a bypass line (14) comprising an inlet (14a) where exhaust gases are received from the exhaust line (3) in a position upstream of the turbine (4, 12, 27) and an outlet (14b) where exhaust gases are led back to the exhaust line (3) in a position downstream of the turbine (4, 12, 27), a first oxidation catalyst (15) and a second oxidation catalyst (19) which are adapted to oxidize nitrogen monoxide to nitrogen dioxide in the exhaust line (3), characterized by the steps of arranging the first oxidation catalyst (15) in the bypass line (14), arranging the second oxidation catalyst (19) in the exhaust line (3) in a position downstream of the bypass line outlet (14b) and controlling the flow and / or temperature of exhaust gases passed through the first oxidation catalyst (15); ) and bypassl so that the first oxidation catalyst (15) and the second oxidation catalyst (19) together provide an oxidation of nitrogen monoxide (NO) to nitrogen dioxide (NO2) in an amount of the exhaust gases leaving the second oxidation catalyst. (19) has a desired distribution of nitrogen monoxide (NO) and nitrogen dioxide (NO2). 21 14 14a 11 2 537 709 1 12 18 16 18 \ 14b --- _----- 24
SE1251092A 2012-09-27 2012-09-27 Arrangement and method for controlling the distribution of nitrogen monoxide and nitrogen dioxide in an exhaust pipe with two oxidation catalysts SE537709C2 (en)

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SE1251092A SE537709C2 (en) 2012-09-27 2012-09-27 Arrangement and method for controlling the distribution of nitrogen monoxide and nitrogen dioxide in an exhaust pipe with two oxidation catalysts
DE112013004219.3T DE112013004219T5 (en) 2012-09-27 2013-09-18 Arrangement and method for the oxidative aftertreatment of exhaust gases from an internal combustion engine
PCT/SE2013/051086 WO2014051500A1 (en) 2012-09-27 2013-09-18 Arrangement and method for oxidative aftertreatment of exhausts from a combustion engine

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GB2547205B (en) * 2016-02-09 2018-02-14 Ford Global Tech Llc An exhaust treatment system with reactant injected into a turbocharger bypass duct
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