US20200040783A1 - Exhaust gas system - Google Patents

Exhaust gas system Download PDF

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Publication number
US20200040783A1
US20200040783A1 US16/600,122 US201916600122A US2020040783A1 US 20200040783 A1 US20200040783 A1 US 20200040783A1 US 201916600122 A US201916600122 A US 201916600122A US 2020040783 A1 US2020040783 A1 US 2020040783A1
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Prior art keywords
flow direction
catalyst
scr catalyst
honeycomb body
exhaust system
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Abandoned
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US16/600,122
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English (en)
Inventor
Rolf Brück
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Vitesco Technologies GmbH
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Vitesco Technologies GmbH
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Assigned to Vitesco Technologies GmbH reassignment Vitesco Technologies GmbH CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: CPT GROUP GMBH
Publication of US20200040783A1 publication Critical patent/US20200040783A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • 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
    • F01N13/0097—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 arranged in a single housing
    • 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
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • 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
    • F01N3/105—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
    • 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
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or 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
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • F01N3/2013—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means
    • F01N3/2026—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means directly electrifying the catalyst substrate, i.e. heating the electrically conductive catalyst substrate by joule effect
    • 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
    • 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
    • F01N2240/16—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 electric heater, i.e. a resistance heater
    • 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
    • F01N2240/40—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 hydrolysis catalyst
    • 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
    • F01N2330/00—Structure of catalyst support or particle filter
    • F01N2330/60—Discontinuous, uneven properties of filter material, e.g. different material thickness along the longitudinal direction; Higher filter capacity upstream than downstream in same housing
    • 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
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/04—Filtering activity of particulate 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
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/22—Monitoring or diagnosing the deterioration of exhaust systems of electric heaters for exhaust systems or their power supply
    • 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
    • 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

Definitions

  • the invention relates to an exhaust system for the aftertreatment of exhaust gases of an internal combustion engine, having, in series as viewed in a flow direction of the exhaust gas, a catalyst for the oxidation of the exhaust gas and/or a catalyst for storing nitrogen oxides, having an introduction point for the feed of a reducing agent, having an SCR catalyst for the selective catalytic reduction of nitrogen oxides, and having a particle filter.
  • catalysts In exhaust-gas aftertreatment systems, different types of catalysts are used in order to ensure the most effective and comprehensive possible conversion and filtering of the pollutants contained in the exhaust gas. Inter alia, use is made, for example, of catalysts which absorb and bind nitrogen oxides (NO x ). Furthermore, catalysts are also known which stimulate a conversion of nitrogen oxides to form less harmful reaction products. Furthermore, filters are known which filter particles of a certain size out of the exhaust gas.
  • NO x nitrogen oxides
  • filters are known which filter particles of a certain size out of the exhaust gas.
  • a disadvantage of the devices known from the prior art for purifying exhaust gases of an internal combustion engine is that the arrangement of the individual catalysts in the exhaust tract is not optimal, and thus the individual catalysts do not achieve their individually optimum action.
  • the so-called SCR catalysts for the selective catalytic reduction of nitrogen oxides are often arranged downstream of the particle filter. This has the result that the SCR catalyst cannot be operated at its optimum operating point.
  • An exemplary embodiment of the invention relates to an exhaust system for the aftertreatment of exhaust gases of an internal combustion engine, having, in series as viewed in a flow direction of the exhaust gas, a catalyst for the oxidation of the exhaust gas and/or a catalyst for storing nitrogen oxides, having an introduction point for the feed of a reducing agent, having an SCR catalyst for the selective catalytic reduction of nitrogen oxides, and having a particle filter, wherein the particle filter is arranged downstream of the SCR catalyst in the flow direction, and a second SCR catalyst and/or an ammonia slippage catalyst is arranged downstream of the particle filter in the flow direction.
  • an SCR catalyst being arranged upstream of the particle filter and an SCR catalyst being arranged downstream of the particle filter, a unit is created which functions more effectively.
  • the operating conditions for SCR catalysts are impaired downstream of the particle filter.
  • the particle filter may generate a large pressure loss, with the result that, at the downstream SCR catalyst, the exhaust gas no longer has a flow speed high enough to ensure optimum conversion.
  • the integration of the SCR catalyst into a particle filter is not optimal, because the commonly used cell densities and cell geometries of the honeycomb bodies of the particle filters are not optimal for the selective catalytic reduction of the exhaust gas in the SCR catalysts.
  • an initial aftertreatment of the exhaust gas is performed, and in particular, with the aid of the reducing agent, typically formed by an aqueous urea solution, which is already introduced and evaporated, a conversion of the nitrogen oxides to form water and nitrogen is performed.
  • the reducing agent typically formed by an aqueous urea solution, which is already introduced and evaporated
  • Purification of the exhaust-gas flow is realized by means of the downstream particle filter.
  • An SCR catalyst positioned downstream of the particle filter may then convert nitrogen oxides that are still present in the exhaust gas.
  • the second SCR catalyst may particularly advantageously have a cell geometry and/or cell density which differs from that of the first SCR catalyst, and may also have a different chemically active coating. It is thus for example possible to realize a conversion of the nitrogen oxides even in the presence of relatively low temperatures and flow speeds.
  • the first SCR catalyst which is arranged upstream of the particle filter in the flow direction, is electrically heatable.
  • the electric heating of the SCR catalyst is advantageous in order to heat the exhaust gas to the required operating temperature as quickly as possible in order to be able to perform the selective catalytic reduction.
  • the first SCR catalyst in the flow direction has an extent of at most 80 mm along the flow direction, wherein the SCR catalyst preferably has an extent of less than 50 mm, wherein the SCR catalyst particularly preferably has an extent of less than 40 mm.
  • a short extent of the first SCR catalyst relative to the particle filter or the second SCR catalyst is advantageous in order that the inflow to the downstream particle filter is influenced only to a small degree, and a good filtering result in the particle filter is thus maintained.
  • a preferred exemplary embodiment is characterized in that the first SCR catalyst in the flow direction is arranged with a spacing to the particle filter along the flow direction of at most 20 mm, preferably of less than 10 mm and particularly preferably of less than 5 mm.
  • the smallest possible spacing is advantageous in order to be able to combine the pressure loss generated owing to the first SCR catalyst and the particle filter. This facilitates the design of the exhaust system.
  • first SCR catalyst in the flow direction and the second SCR catalyst in the flow direction are formed as a modular unit with the particle filter. This is advantageous in order to facilitate the assembly process.
  • the SCR catalysts and the particle filter are formed by a common honeycomb body. This is advantageous in order to minimize the number of installed elements, whereby the assembly process is simplified.
  • the honeycomb body of the particle filter has a cell geometry and/or cell density which differs from that of the honeycomb body of the first SCR catalyst in the flow direction and from that of the honeycomb body of the second SCR catalyst in the flow direction. This is particularly advantageous in order to optimally adapt the individual components to their respective intended use and, overall, achieve the smallest possible pressure loss across the individual components. Furthermore, by means of the cell geometries, it is for example possible to influence the filter characteristics and the speed distribution.
  • the cell geometry and/or the cell density and/or the chemically active coating of the honeycomb body and/or the amount of coating of the honeycomb body of the first SCR catalyst in the flow direction differs from the cell geometry and/or the cell density and/or the chemically active coating of the honeycomb body of the second SCR catalyst in the flow direction.
  • a changed exhaust-gas composition is also to be expected in the region of the second SCR catalyst, because the latter is positioned downstream of the particle filter. It is thus possible, for example, to use a higher cell density and/or a reduced cell cross section without the risk of blockage of the flow channels formed in the honeycomb body. It is also possible for the coating to be advantageously adapted to the generally lower concentration of ammonia and nitrogen oxides, in order to nevertheless realize as comprehensive as possible a conversion of the nitrogen oxides.
  • the amount of coating of the first SCR catalyst in the flow direction is preferably greater than the amount of coating of the second SCR catalyst in the flow direction.
  • FIG. 1 shows a sectional view through an exemplary exhaust tract with a multiplicity of catalysts.
  • FIG. 1 shows a sectional view through an exhaust tract of an exhaust system 1 .
  • the exhaust system 1 has a multiplicity of catalysts, which are arranged in casings and which are connected to one another by pipelines such that exhaust gas flows through the catalysts.
  • a catalyst 3 for the oxidation of the exhaust gas is arranged first in the flow direction 2 of the exhaust gas.
  • an introduction point 4 through which a reducing agent, such as for example an aqueous urea solution, is introduced into the exhaust tract.
  • a reducing agent such as for example an aqueous urea solution
  • evaporation element 5 arranged immediately adjacent to this introduction point 4 is an evaporation element 5 , on which the reducing agent is evaporated in order to subsequently react, as ammonia, with the nitrogen oxides in the exhaust gas.
  • a first SCR catalyst 6 in which the nitrogen oxides in the exhaust gas react with the ammonia and the chemically active coating of the SCR catalyst 6 and thus form nitrogen and water.
  • a particle filter 7 Positioned downstream of the first SCR catalyst 6 is a particle filter 7 , which serves for filtering the exhaust gas and which filters in particular soot particles out of the exhaust gas.
  • the particle filter 7 is followed by a second SCR catalyst 8 .
  • the same reaction takes place in the second SCR catalyst as in the first SCR catalyst 6 .
  • the advantage of such a construction lies in the fact that a reduction of the nitrogen oxides in the exhaust gas takes place already before the exhaust gas flows into the particle filter.
  • the exhaust gas flowing into the first SCR catalyst is therefore still at a particularly high temperature, and also the exhaust-gas distribution over the cross section of the flow path has not yet been adversely affected by the particle filter. In this way, a particularly effective conversion of the nitrogen oxides in the exhaust gas may take place.
  • the second SCR catalyst serves substantially for reducing that nitrogen oxide fraction which has not yet been reduced in the first SCR catalyst.
  • an ammonia slippage catalyst may also be installed, which may bind excess ammonia (NH 3 ) that has not been converted during the reduction of the nitrogen oxides in the exhaust gas. In this way, it is for example possible to prevent a breakthrough of ammonia into the exhaust tailpipe, which could result in ammonia escaping into the surroundings and lead to an unpleasant smell or to contamination of the environment.
  • FIG. 1 The exemplary embodiment in FIG. 1 is in particular not of a limiting nature, and serves for illustrating the concept of the invention.

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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)
  • Materials Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
US16/600,122 2017-04-13 2019-10-11 Exhaust gas system Abandoned US20200040783A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102017206425.0 2017-04-13
DE102017206425.0A DE102017206425A1 (de) 2017-04-13 2017-04-13 Abgassystem
PCT/EP2018/058157 WO2018188968A1 (de) 2017-04-13 2018-03-29 Abgassystem

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2018/058157 Continuation WO2018188968A1 (de) 2017-04-13 2018-03-29 Abgassystem

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US20200040783A1 true US20200040783A1 (en) 2020-02-06

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US16/600,122 Abandoned US20200040783A1 (en) 2017-04-13 2019-10-11 Exhaust gas system

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US (1) US20200040783A1 (ko)
EP (1) EP3610141A1 (ko)
JP (1) JP2020516815A (ko)
KR (1) KR20190122259A (ko)
CN (1) CN110537008A (ko)
DE (1) DE102017206425A1 (ko)
WO (1) WO2018188968A1 (ko)

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DE102019131829B3 (de) * 2019-11-25 2021-01-14 Volkswagen Aktiengesellschaft Verfahren zur Abgasnachbehandlung eines Verbrennungsmotors

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JP2020516815A (ja) 2020-06-11
KR20190122259A (ko) 2019-10-29

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