SE539078C2 - Arrangement comprising an exhaust generating device and an exhaust gas aftertreatment device - Google Patents

Arrangement comprising an exhaust generating device and an exhaust gas aftertreatment device Download PDF

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Publication number
SE539078C2
SE539078C2 SE1451241A SE1451241A SE539078C2 SE 539078 C2 SE539078 C2 SE 539078C2 SE 1451241 A SE1451241 A SE 1451241A SE 1451241 A SE1451241 A SE 1451241A SE 539078 C2 SE539078 C2 SE 539078C2
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SE
Sweden
Prior art keywords
exhaust
exhaust gas
damper
zone
channel
Prior art date
Application number
SE1451241A
Other languages
Swedish (sv)
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SE1451241A1 (en
Inventor
Gyllin Magnus
Original Assignee
Scania Cv Ab
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Publication date
Application filed by Scania Cv Ab filed Critical Scania Cv Ab
Priority to SE1451241A priority Critical patent/SE539078C2/en
Priority to DE102015013246.6A priority patent/DE102015013246A1/en
Publication of SE1451241A1 publication Critical patent/SE1451241A1/en
Publication of SE539078C2 publication Critical patent/SE539078C2/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • 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
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • 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
    • F01N3/24—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 constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2892—Exhaust flow directors or the like, e.g. upstream of catalytic device
    • 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
    • F01N2240/20—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 a flow director or deflector
    • 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
    • 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
    • F01N2470/00—Structure or shape of gas passages, pipes or tubes
    • F01N2470/30—Tubes with restrictions, i.e. venturi or the like, e.g. for sucking air or measuring mass flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1404—Exhaust gas temperature
    • 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)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

19 ABSTRACT An arrangement comprising an exhaust generating device (2), forinstance in the form of a combustion engine, and an exhaust gasaftertreatment device (20) provided with: - a mixing channel (23) having an entry zone (25) of reducedcross-sectional area at its upstream end; - an injector (26) for injecting liquid reducing agent into aninjection zone (27) of reduced exhaust pressure in the mixingchannel downstream of the entry zone; - a catalytic converter (28) arranged downstream of the mixingchannel (23); - a bypass channel (33), via which exhaust gas may bypass theentry zone; and - an adjustable damper (36) for controlling the exhaust flowthrough the bypass channel (33), the damper being controlled by an electronic control device (6). (Fi9 1)

Description

AND PRIOR ART The present invention relates to an arrangement according to thepreamble of claim 1 comprising an exhaust generating device and an exhaust gas aftertreatment device. ln order to meet present exhaust emission regulations, present-day motor vehicles are usually provided with a catalytic converterin the exhaust line in order to achieve a catalytic conversion ofharmful exhaust into less environmentally components environmentally harmful substances. One method used for achieving an efficient catalytic conversion is based on theinjection of a reducing agent into the exhaust gas upstream ofthe catalytic converter. A reducing substance included in orformed by the reducing agent is carried by the exhaust gas intothe catalytic converter and absorbed on active sites in thecatalytic converter, which results in an accumulation of thereducing substance in the catalytic converter. The accumulatedreducing substance may then react with an exhaust substance forconversion of this exhaust substance into a substance with lessenvironmental influence. Such a catalytic converter may forinstance be of the SCR type (SCR = Reduction). This type of catalytic converter is in the following Selective Catalytic denominated SCR catalyst. An SCR catalyst reduces NOX in theexhaust gas. A reducing agent in the form of urea is normally injected into the exhaust gas upstream of an SCR catalyst. When urea is injected into the exhaust gas, ammonia is formed, andthis ammonia constitutes the reducing substance that contributesto the catalytic conversion in the SCR catalyst. The ammonia isaccumulated in the SCR catalyst by being absorbed on activesites in the SCR catalyst, and NOX present in the exhaust gas isconverted into nitrogen gas and water when brought into contactwith accumulated ammonia at the active sites in the SCR catalyst.
When urea is used as reducing agent, it is injected into theexhaust line in the form of a liquid urea solution by means of aninjector. The injector comprises a nozzle, through which the ureasolution, under pressure, is injected into the exhaust line inatomized form as a spray. A combustion engine, for instance inthe form of a diesel engine in a motor vehicle, is often operatedunder such conditions that the exhaust gas from the combustionengine has a sufficiently high temperature to be able to vaporizeinjected urea solution so that ammonia is formed. However,under some operating conditions, the temperature of the exhaustgas may be too low for an efficient vaporization of injected ureasolution. Furthermore, it is difficult, also in the first-mentionedcase with high exhaust gas temperature, to avoid that some ofthe injected urea solution comes into contact with and gets stuckto an internal wall surface of the exhaust line in an unevaporatedstate. When a combustion engine is operated in a uniformmanner for a period of time, i.e. during a stationary operatingcondition, there are minimal variations in the exhaust flow, andthe urea solution injected into the exhaust gas will therefore hitessentially the same area of the exhaust line throughout this period of time. Under the effect of the rather cool urea solution, the temperature in this area of the exhaust line may be reducedlocally to a temperature which is so low that a film of ureasolution is formed in this area and then carried along with theexhaust flow. When this film has been moved a certain distancein the exhaust line, the water in the urea solution will boil offunder the effect of the hot exhaust gas and leave behind solidurea which slowly evaporates by the heat in the exhaust line. lfthe formation of solid urea is more rapid than the evaporation ofthe solid urea previously formed, solid urea will accumulate inthe exhaust line. lf the layer of urea becomes sufficiently thick,the urea and its decomposition products will react with eachother to form urea-based primitive polymers, so-called urealumps. Such urea lumps may, in course of time, block the exhaust line.
OBJECT OF THE INVENTION The object of the present invention is to achieve improvedpossibilities of ensuring a good vaporization of reducing agent injected into a mixing channel of an exhaust gas aftertreatment device.
SUMMARY OF THE INVENTION According to the present invention, the above-mentioned objectis achieved by an arrangement having the features defined in claim 1.
The arrangement of the present invention comprises an exhaust generating device, for instance in the form of a combustion engine, and an exhaust gas aftertreatment device, wherein theexhaust gas aftertreatment device is provided with: - an inlet for receiving exhaust gas from the exhaust generatingdevice; - an outlet for emitting the exhaust gas after the passage of theexhaust gas through the exhaust gas aftertreatment device; - a mixing channel arranged downstream of the inlet and havingan entry zone of reduced cross-sectional area at its upstreamend; - an injector for injecting liquid reducing agent into an injectionzone of reduced exhaust pressure in the mixing channeldownstream of the entry zone, wherein the entry zone has such across-sectional area that an exhaust pressure in the injectionzone equal to or lower than the prevailing vapor pressure of theinjected reducing agent may be generated under some operatingconditions of the exhaust generating device; - a catalytic converter arranged downstream of the mixingchanneh - a bypass channel, via which exhaust gas flowing through theexhaust gas aftertreatment device may bypass the entry zone ofthe mixing channel before flowing into the catalytic converter;and - an adjustable damper for controlling the exhaust flow throughthe bypass channel, the damper being moveable between aclosed position, in which the damper prevents exhaust flowthrough the bypass channel, and an open position, in which thedamper allows exhaust flow through the bypass channel.
The arrangement further comprises an electronic control device which is configured to control the position of the damper.
By means of the above-mentioned entry zone of reduced cross-sectional area at the upstream end of the mixing channel, it willbe possible, when the damper is in the closed position and theexhaust flow is directed into the mixing channel via the entryzone, to achieve an exhaust pressure in the injection zone equalto or lower that the prevailing vapor pressure of the reducingagent injected into the injection zone so that the reducing agentwill vaporize almost instantly when injected into the injectionzone. When no reducing agent is injected into the injection zone,the damper may be in the open position so that the exhaust gasis allowed to flow through the bypass channel and therebybypass the entry zone of the mixing channel. Hereby, the entryzone of the mixing channel is prevented from causing anundesired increase of the back-pressure in the exhaust line atthe moments when no into the reducing agent is injected injection zone.
Further advantageous features of the arrangement of the presentinvention will appear from the following description and the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, a specific descriptionof preferred embodiments of the invention cited as examplesfollows below. ln the drawings: Fig 1 is an outline diagram of an arrangement according to a first embodiment of the present invention, Fig 2 is an outline diagram of an arrangement according to a second embodiment of the present invention,Fig 3a is a schematic illustration of a part of an exhaust gasaftertreatment device included in the arrangement ofFigs 1 and 2, with a damper included in the exhaustgas aftertreatment device shown in a closed positionat a moment when reducing agent is injected into amixing channel of the exhaust gas aftertreatment device, andFig 3b is a schematic illustration corresponding to Fig 3a, butwith the damper shown in an open position at amoment when no reducing agent is injected into the mixing channel.
DETAILED DESCRIPTION OF EMBODIMENTS OF THEINVENTION An arrangement 1 according to two embodiments of the presentillustrated and 2. The arrangement 1 comprises an exhaust generating device 2 and an invention is schematically in Figs 1exhaust gas aftertreatment device 20. The exhaust generatingdevice 2 is for instance a combustion engine in the form of aheavy diesel or gas engine. Combustion air is fed into theexhaust generating device 2 through an air inlet channel 3. Anexhaust conduit 4 is connected to the exhaust generating device2. The exhaust gas produced by the exhaust generating device 2is conducted through the exhaust conduit 4 and enters into the surroundings via an exhaust gas outlet 5. Before reaching the exhaust gas outlet 5, the exhaust gas from the exhaustgenerating device 2 flows through the exhaust gas aftertreatment device 20 which is arranged in the exhaust conduit 4.
The exhaust gas aftertreatment device 20 comprises:inlet 21 generating device 2; - an for receiving exhaust gas from the exhaust- an outlet 22 for emitting the exhaust gas after the passage ofthe exhaust gas through the exhaust gas aftertreatment device20; - a mixing channel 23 arranged downstream of said inlet 21,wherein the mixing channel 23 is delimited in the radial directionby a tubular wall 24 and has an entry zone 25 of reduced cross-sectional area at its upstream end; - an injector 26, in the form of an injection nozzle or the similar,for injecting liquid reducing agent into an injection zone 27 ofreduced exhaust pressure in the mixing channel 23 closelydownstream of the entry zone 25; and - a catalytic converter 28 arranged downstream of the mixing channel 23 between the mixing channel and the outlet 22. ln the mixing channel 23, the reducing agent injected by theinjector 26 is mixed with exhaust gas flowing through the mixingchannel and vaporized under the effect of the heat of the exhaust gas.
The cross-sectional area at the entry zone 25 of the mixingchannel 23 is smaller than the cross-sectional area of the mixingchannel 23 at the injection zone 27 downstream of the entry zone and also smaller than the cross-sectional area of the exhaust channel upstream of the entry zone 25. Hereby, the exhaustpressure in the injection zone 27 will be lower than the exhaustpressure upstream of the entry zone 25 when exhaust gas isflowing through the entry zone 25. The entry zone 25 is designedwith such a cross-sectional area that an exhaust pressure in theinjection zone 27 equal to or lower than the prevailing vaporpressure of the reducing agent injected into the injection zone 27may be generated under some operating conditions of theexhaust generating device 2 to thereby enable a complete andalmost immediate vaporization of the reducing agent injected into the injection zone 27.
The catalytic converter 28 is preferably an SCR catalyst, whereinthe injector 26 is configured to inject reducing agent in the formof urea into exhaust gas passing through the mixing channel 23. illustrated the exhaust aftertreatment device 20 also comprises a particulate filter 29 ln the embodiment in Fig 1, gasarranged upstream of the mixing channel 23 and an oxidationcatalyst 30 arranged upstream of the particulate filter 29 betweenthe inlet 21 and the particulate filter, wherein a connectingchannel 31 extends between an outlet of the particulate filter 29and the entry zone 25 of the mixing channel 23. The oxidationcatalyst 30, the particulate filter 29, the mixing channel 23 andthe catalytic converter 28 are arranged in series with each otherbetween the inlet 21 and the outlet 22 of the exhaust gas aftertreatment device 20.
A storage container 10 for reducing agent is connected to the injector 26 through a supply conduit 11. The supply of reducing agent to the injector 26 is regulated by means of a regulatingvalve 12 arranged in the supply conduit 11. By means of thisvalve 12, it is possible to control the amount of reducing agent tobe injected into the exhaust line, i.e. the dosing of the reducingagent. A pump 13 is arranged in the supply line 11 between thestorage container 10 and the regulating valve 12 in order to feedreducing agent from the storage container 10 to the regulatingvalve 12.
A bypass channel 33 is provided in the exhaust gasaftertreatment device 20, wherein exhaust gas flowing throughthe exhaust gas aftertreatment device 20 towards the catalyticconverter 28 may bypass the entry zone 25 of the mixing channel23 via this bypass channel 33 before flowing into the catalyticconverter 28. ln the illustrated embodiment, the bypass channel33 has an inlet 34 which is connected to the above-mentionedconnecting channel 31 at a point of the connecting channellocated upstream of the entry zone 25, whereas the outlet 35 ofthe bypass channel 33 is connected to the mixing channel 23 at apoint of the mixing channel located downstream of the entry zone25, i.e. between the entry zone 25 and the inlet of the catalyticconverter 28.The exhaust gas aftertreatment device 20 comprises anadjustable damper 36 for controlling the exhaust flow through thebypass channel 33. The damper 36 preferably has the form of adisc or plate. The damper 36 is moveable by means of anactuator 37 between a closed position (see Figs 1, 2 and 3a), inwhich the damper 36 prevents exhaust flow through the bypass channel 33, and an open position (see Fig 3b), in which the damper 36 allows exhaust flow through the bypass channel 33.Thus, the exhaust flow is directed through the entry zone 25 ofthe mixing channel 23 and into the injection zone 27 when thedamper 36 is in the closed position, and when the damper 36 isin the open position the exhaust flow, or at least the main part33 without thereof, is directed through the bypass channel passing the entry zone 25 of the mixing channel 23.
The actuator 37 is with advantage an electric motor, but anyother suitable type of actuator having a sufficiently quickresponse time may be used for adjusting the position of thedamper 36. The damper 36 is preferably pivotally mounted so asto be pivotable between the closed and open positions by meansof the actuator 37. ln the illustrated embodiment, the damper 36is pivotable about a pivot axis 38 (see Figs 3a and 3b) located atone end of the damper. A stop member 39 is with advantageprovided in the bypass channel 33 in order to define the closedposition of the damper 36, wherein the damper 36 is configuredto abut against the stop member 39 in its closed position. Thedamper 36 may be mounted at the inlet 34 of the bypass channel33, as illustrated in the figures, or alternatively at the outlet 35 ofthe bypass channel 33 or at a location in the bypass channel 33 between the inlet 34 and the outlet 35 thereof.
The arrangement 1 comprises an electronic control device 6which is configured to control the operation of the actuator 37 tothereby control the position of the damper 36. The electroniccontrol device 6 is configured to make the damper 36 assume theabove-mentioned open position at moments when no reducing agent is injected into the injection zone 27 and to assume, at 11 least under certain predetermined operating conditions, theabove-mentioned closed position at each moment when reducing agent is injected into the injection zone 27.
Under some operating conditions, the temperature of the exhaustgas flowing through the mixing channel 23 might be so high thatthe injected reducing agent is completely vaporized withoutrequiring that the exhaust pressure in the injection zone 27 islower than the prevailing vapor pressure of the reducing agent.The electronic control device 6 may be configured to make thedamper 36 assume a position between the above-mentionedopen and closed positions at moments when reducing agent isinjected into the injection zone 27 under such operating conditions. ln the illustrated embodiments, the electronic control device 6that controls the position of the damper 36 is also configured tocontrol the above-mentioned regulating valve 12 in accordancewith previously known control algorithms and to control the operation of the exhaust generating device 2.
The prevailing vapor pressure of the reducing agent 7 injectedinto the mixing channel 23 by the injector 26 depends on theprevailing temperature of the reducing agent when received inthe mixing channel. This temperature depends, in its turn, on thetemperature of the reducing agent before it leaves the injector 26and the exhaust temperature to which the reducing agent issubjected when it has been injected into the mixing channel 23.ln the illustrated embodiment, the arrangement 1 comprises a temperature sensor 8 for establishing a temperature value 12 related to the temperature of the reducing agent to be injectedinto the injection zone 27. This temperature sensor 8 may belocated in the regulating valve 12, as illustrated in Fig 1. Theelectronic control device 6 is configured to receive saidtemperature value. lf the temperature of the reducing agent to beinto the injected injection zone 27 can be expected to be essentially constant during the operation of the exhaust generating device 2, the temperature sensor 8 may be omitted.
The exhaust pressure in the injection zone 27 depends on thefollowing variables: -the exhaust pressure in the connecting channel 31 upstream ofthe entry zone 25 of the mixing channel 23; -the mass flow of the exhaust gas flowing through the entry zone25;and - the density of the exhaust gas flowing through the entry zone25, wherein this density in its turn depends on the composition of the exhaust gas.
The above-mentioned variables and the exhaust temperaturedepend on the prevailing operating conditions of the exhaustgenerating device 2. The electronic control device 6 is configuredto control the operation of the exhaust generating device 2 on thebasis of the above-mentioned temperature value so as to makesure that the above-mentioned variables and the exhausttemperature have such values that an exhaust pressure in theinjection zone 27 equal to or lower than the prevailing vaporpressure of the injected reducing agent is generated when thereducing agent is injected into the injection zone 27. When the exhaust generating device 2 is a combustion engine, the 13 electronic control device 6 is configured to control the engineload and the engine speed of the combustion engine. ln the timeperiods between the moments when reducing agent is injectedinto the injection zone 27, i.e. when the damper 36 is in the openposition, the exhaust generating device 2 may be operated without taking the above-mentioned temperature value into account The electronic control device 6 may be implemented by onesingle electronic control unit, as illustrated in Figs 1 and 2.However, the electronic control device 6 could as an alternativebe implemented by two or more mutually co-operating electroniccontrol units.
The exhaust generating device 2 could for instance be a combustion engine for marine or industrial use. ln the example illustrated in Fig 1, the exhaust generating device2 is a combustion engine provided with a turbo charger 15 inorder to achieve supercharging, i.e. forced air supply to theThe compressor wheel 16 arranged in the air inlet channel 3 and a combustion engine. turbo charger 15 comprises a turbine wheel 17 arranged in the exhaust conduit 4. Thecompressor wheel 16 is driven by the turbine wheel 17, which inits turn is driven in rotation by the exhaust gas from thecombustion engine 2. The compressor wheel 16 and the turbinewheel 17 are operably connected to each other, e.g. by being placed on one and the same shaft. 14 ln the example illustrated in Fig 2, the flow of air into the exhaustgenerating device 2 through the air inlet channel 3 is achieved without any turbo charger.
The invention is of course not in any way restricted to the em-bodiments described above. On the contrary, many possibilitiesto modifications thereof will be apparent to a person with ordi-nary skill in the art without departing from the basic idea of the invention such as defined in the appended claims.

Claims (12)

_ An arrangement comprising an exhaust generating device (2), for instance in the form of a combustion engine, and anexhaust gas aftertreatment device (20), wherein the exhaustgas aftertreatment device (20) is provided with: - an inlet (21) for receiving exhaust gas from the exhaustgenerating device (2); - an outlet (22) for emitting the exhaust gas after the passageof the exhaust gas through the exhaust gas aftertreatmentdevice (20); - a mixing channel (23) arranged downstream of the inlet (21)and having an entry zone (25) of reduced cross-sectional areaat its upstream end; - an injector (26) for injecting liquid reducing agent into aninjection zone (27) of reduced exhaust pressure in the mixingchannel (23) downstream of the entry zone (25); and - a catalytic converter (28) arranged downstream of the mixingchannel (23); characterized in: - that the exhaust gas aftertreatment device (20) comprises abypass channel (33), via which exhaust gas flowing throughthe exhaust gas aftertreatment device (20) may bypass theentry zone (25) of the mixing channel (23) before flowing intothe catalytic converter (28); - that the exhaust gas aftertreatment device (20) comprisesan adjustable damper (36) for controlling the exhaust flowthrough the bypass channel (33), the damper (36) beingmoveable between a closed position, in which the damper (36) prevents exhaust flow through the bypass channel (33), 2. 3. 4. 16 and an open position, in which the damper (36) allowsexhaust flow through the bypass channel (33); - that the entry zone (25) has such a cross-sectional area thatan exhaust pressure in the injection zone (27) equal to orlower than the prevailing vapor pressure of the injectedreducing agent may be generated under some operatingconditions of the exhaust generating device (2); and - that the arrangement (1) comprises an electronic controldevice (6) which is configured to control the position of the damper (36). An arrangement according to claim 1, characterized in: - that the damper (36) is pivotally mounted so as to bepivotable between the open position and the closed position;and - that the exhaust gas aftertreatment device (20) comprisesan actuator (37) for pivoting the damper (36), wherein theelectronic control device (6) is configured to control theoperation of the actuator (37) to thereby control the position of the damper (36). An arrangement according to claim 2, characterized in that the actuator (37) is an electric motor. 1-3, characterized in that the electronic control device (6) is An arrangement according to any of claims configured to make the damper (36) assume said openposition at moments when no reducing agent is injected into the injection zone. _ An arrangement 17 1-4, characterized in that the bypass channel (33) has an outlet An arrangement according to any of claims (35) which is connected to the mixing channel (23) at a pointof the mixing channel located downstream of the entry zone(25). An arrangement according to any of claims 1-5,characterized in: - that the arrangement (1) comprises a temperature sensor (8)the temperature of the reducing agent to be injected into the for establishing a temperature value related toinjection zone (27); and - that the electronic control device (6) is configured to receivesaid temperature value and to control the operation of theexhaust generating device (2) on the basis of the temperaturevalue in such a manner that an exhaust pressure in theinjection zone (27) equal to or lower than the prevailing vaporpressure of the injected reducing agent is generated when the reducing agent is injected into the injection zone (27). 1-6, characterized in that the catalytic converter (28) is an SCR according to any of claims catalyst. 1-7, characterized in that the exhaust gas aftertreatment device An arrangement according to any of claims (20) comprises a particulate filter (29) arranged upstream of the mixing channel (23). 9. 18 An arrangement according to claim 8, characterized in thatthe exhaust gas aftertreatment device (20) comprises anoxidation catalyst (30) arranged upstream of the particulatefilter (29). 10.An arrangement according to claim 8 or 9, characterized in 11 .An that the exhaust gas aftertreatment device (20) comprises aconnecting channel (31) extending between an outlet of theparticulate filter (29) and the entry zone (25) of the mixingchannel (23), wherein the bypass channel (33) has an inlet(34) which is connected to the connecting channel (31) at apoint of the connecting channel located upstream of the entryzone (25).
1. -10,characterized in that the exhaust generating device (2) is a arrangement according to any of claims combustion engine, preferably a diesel or gas engine. 12.An arrangement according to claim 11, characterized in that the exhaust generating device (2) is a combustion engine for marine or industrial use.
SE1451241A 2014-10-16 2014-10-16 Arrangement comprising an exhaust generating device and an exhaust gas aftertreatment device SE539078C2 (en)

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SE1451241A SE539078C2 (en) 2014-10-16 2014-10-16 Arrangement comprising an exhaust generating device and an exhaust gas aftertreatment device
DE102015013246.6A DE102015013246A1 (en) 2014-10-16 2015-10-12 Arrangement comprising an exhaust gas generating device and an exhaust gas aftertreatment device

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SE1451241A SE539078C2 (en) 2014-10-16 2014-10-16 Arrangement comprising an exhaust generating device and an exhaust gas aftertreatment device

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SE1451241A1 SE1451241A1 (en) 2016-04-17
SE539078C2 true SE539078C2 (en) 2017-04-04

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EP3492718B1 (en) * 2017-11-30 2020-06-10 Katcon Global S.A. Exhaust line for a vehicle

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