WO2000008314A1 - Systeme d'echappement comportant un dispositif de reduction catalytique de nox et un element support de pot catalytique a base de fibres - Google Patents

Systeme d'echappement comportant un dispositif de reduction catalytique de nox et un element support de pot catalytique a base de fibres Download PDF

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Publication number
WO2000008314A1
WO2000008314A1 PCT/DE1999/002319 DE9902319W WO0008314A1 WO 2000008314 A1 WO2000008314 A1 WO 2000008314A1 DE 9902319 W DE9902319 W DE 9902319W WO 0008314 A1 WO0008314 A1 WO 0008314A1
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WO
WIPO (PCT)
Prior art keywords
exhaust system
ammonia
catalyst
layers
injection device
Prior art date
Application number
PCT/DE1999/002319
Other languages
German (de)
English (en)
Inventor
Alfred Buck
Axel Hartenstein
Original Assignee
Alfred Buck
Axel Hartenstein
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alfred Buck, Axel Hartenstein filed Critical Alfred Buck
Priority to AU61876/99A priority Critical patent/AU6187699A/en
Publication of WO2000008314A1 publication Critical patent/WO2000008314A1/fr

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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
    • 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]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9431—Processes characterised by a specific 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
    • 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
    • F01N3/0217—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 the filtering elements having the form of hollow cylindrical bodies
    • 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
    • F01N3/022—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 characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
    • F01N3/0226—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 characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous the structure being fibrous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
    • 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
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • F01N3/2835—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support fibrous
    • 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
    • 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
    • F01N3/30—Arrangements for supply of additional air
    • F01N3/32—Arrangements for supply of additional air using air pump
    • 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
    • F01N2330/00—Structure of catalyst support or particle filter
    • F01N2330/10—Fibrous material, e.g. mineral or metallic wool
    • 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
    • F01N2330/12—Metallic wire mesh fabric or knitting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/12—Hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/08—Adding substances to exhaust gases with prior mixing of the substances with a gas, e.g. air
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • So-called SCR catalysts are used to largely remove the nitrogen oxide from the exhaust gas stream.
  • SCR catalysts are particularly suitable for practically completely eliminating very high levels of nitrogen oxide. At high nitrogen oxide loads in the exhaust gas, they work more effectively than catalysts in which the catalyst material is firmly seated on a substrate.
  • SCR catalysts have also advantages in internal combustion engines, which have a considerable amount of carbon black because the Rußanceil to rial down strike in the catalyst bodies' with applied also in the surface of catalyst material on the Katalysacormate- and make it ineffective. That's why SCR catalytic converter devices are particularly advantageous for diesel engines.
  • the exhaust gas stream loaded with the urea reaches a swirling device in which a particularly good mixing of the exhaust gas stream with the solution is to be achieved.
  • the droplet size of the lost solution is reduced in the swirling device in order to obtain a corresponding increase in surface area.
  • part of the NO : ⁇ already reacts with the ammonia.
  • a reduction catalytic converter connects to the outlet of the swirling device, the subscrat of which is coated with vanadium pentoxide or platinum.
  • the substrate of this catalyst is a monolith with a variety of gas channels.
  • the reduction catalyst is followed by an oxide acion catalyst, the substrate of which is also a perforated brick which is coated with platinum or palladium.
  • the fiber-based catalyst device also acts as a particle or soot filter in which the soot is trapped and is also oxidized to carbon dioxide with the aid of the catalytic coating.
  • the fibers with the catalytic coating act as an equal carrier for the previously unused amount of ammonia-containing solution, which is deposited extremely finely on the fibers and thus forms a very large reaction surface for nitrogen oxide that is still present.
  • the fibers are preferably processed into a textile fabric in which they are firmly anchored. It has turned demonstrated that a knitted fabric is a textile fabric that is particularly suitable for catalytic converters, that holds the fibers very well and does not dissolve even when the thread breaks. A knitted fabric can be laid very well even with stubborn fibers, without forming unwanted small folds that create large-volume gas channels through which the exhaust gas can flow uncleaned.
  • a particularly good filter and catalyst effect is achieved if the knitted fabric forms layers which lie directly on top of one another and are preferably connected to one another along one edge, if appropriate.
  • Such layers are obtained when the knitted fabric is manufactured as a continuous tubular material, which is then laid flat to form a band.
  • the double-layer tape obtained is folded in a zigzag shape in order to obtain the desired layers stacked one on top of the other.
  • the stack of knitted layers obtained in this way is arranged in the catalyst device in such a way that the gas flow is forced to flow through between the layers of the knitted fabric.
  • Another possibility of obtaining the desired layers of knitted fabric is to compress the knitted tube in the longitudinal direction of the tube, which creates annular layers which are also one above the other and are connected to one another on the inside and outside edge.
  • the knitted fabric can be made of metallic and / or mineral fibers which are coated accordingly with catalyst material, for example vanadium pentoxide, or contain this material.
  • a nozzle which has very favorable properties has slit-shaped outlets for the air and essentially circular outlets for the ammonia-donating agent, the slit-shaped nozzle outlets for the ammonia-donating agent surrounding it.
  • ammonia itself is toxic, it is advantageous not to keep the ammonia in the immediate form in the vehicle or in the vicinity of the internal combustion engine. Even the smallest leakage could lead to a hazard. It is therefore cheaper to use urea or urea carbamate or other compounds instead of ammonia, in which no free ammonia is present and which give rise to the ammonia when heated. This makes handling much less dangerous.
  • Fig. 1 is an exhaust system according to the invention in one schematic longitudinal section
  • Fig. 4 shows the nozzle, injection device in a schematic longitudinal section
  • Fig. 5 shows the nozzle of Fig. 4 in a plan view of the outlet side.
  • Fig. 1 shows a schematic representation of an exhaust system 1 for an internal combustion engine 2, which is preferably a diesel engine.
  • the exhaust system I includes an exhaust duct 3, which at its upstream end merges into an exhaust manifold 4, which is connected to the outlets of the diesel engine 2. Downstream of the exhaust manifold 4, an injection device 5 opens into the gas duct 3.
  • the injection device 5 is used to inject a reaction medium, which contains ammonia or splits into ammonia, into the exhaust gas duct 3.
  • the exhaust duct 3 Downstream, the exhaust duct 3 contains a plurality of swirling devices 6, 7 and 8 arranged one behind the other.
  • the gas stream emerging from the last intermingling device 8 finally arrives in a catalytic converter device 9. After flowing through the catalytic converter device 9, the cleaned exhaust gas stream is blown out into the open via an opening 11.
  • a speed sensor 12 is directly or indirectly coupled to the crankshaft of the diesel engine 2 and outputs a signal proportional to the engine speed via a signal line 13.
  • the signal reaches a converter circuit 14, which emits a control signal to a control circuit 16 on an electrical line 15.
  • the control circuit 16 serves to control a liquid pump 17 and a compressor 18.
  • the liquid pump 17 is connected to the control circuit 16 via an electrical line 18 and the compressor 18 via an electrical line 21.
  • At least the liquid pump 17 is of a type which is continuously Petite adjustment of the volume flow permitted.
  • the liquid pump 17 has two connections 22 and 23, the connection 22 being on the suction side and the connection 23 on the pressure side.
  • the suction connection 22 is connected to a storage container 25 via a pipeline 24.
  • an aqueous solution e.g. composed of 40% urea and 60% water.
  • the aqueous urea solution can be refilled into the storage container 25 with the aid of a filling line 26 which continues to open into the storage container and is to be shut off via a shut-off valve 27.
  • the pressure connection 23 is connected in terms of flow to a nebulizer nozzle 29 via a pipeline 28.
  • the atomizing nozzle 25 is set up to atomize the aqueous urea solution as finely as possible, and it also has the task of introducing additional air into the exhaust gas duct 3, which should also be mixed well with the exhaust gas stream.
  • the atomizer nozzle 29 therefore contains a larger set of nozzle openings which are connected via a line 31 to a pressure connection 32 of the compressor 18.
  • the compressor 18 draws in circulating air and presses it into the line 31.
  • the swirling devices 6, 7 and 8 arranged downstream of the atomizing nozzle 29 are essentially baffle plates arranged at an angle, the purpose of which is to improve the distribution of the atomized urea solution, ie to mix the exhaust gas stream evenly with the atomized aqueous solution and at the same time, if necessary, to increase the droplet size reduce. This is intended to create a large surface area on which the nitrogen oxides of the exhaust gas stream can react with the ammonia.
  • the catalyst device 9 consists of a mineral fiber knit whose fibers are coated with vanadium pentoxide.
  • FIGS. 2a and 2b The structure of the catalyst device 9, which is only indicated very schematically in FIG. 1, is shown in more detail in FIGS. 2a and 2b.
  • the substrate for the catalyst material vanadium pentoxide as can be seen in FIG. 2a, consists of a circular knitted tube 33 in which loops 34 are indicated.
  • the stitches 34 form rows of stitches 35 which run in the circumferential direction of the knitted tube 33 and so-called wales 36 which lie in the longitudinal direction of the knitted tube 33.
  • the threads from which the hose 33 is knitted are monofilaments or fibers or a mixture of the two.
  • the material of the fibers are minerals, such as glass and quartz or metals, which are sufficiently heat-resistant.
  • the catalyst material was applied to these fibers of the knitted fabric.
  • the knitted tube produced in this way on a circular knitting machine is compressed in the longitudinal direction to form the catalyst device, as shown in the lower part of FIG. 2a. Seen from the outside, this gives it the shape of a tree cake or an accordion, forming circular layers 37 which lie one on top of the other in the finished catalytic converter. For the purpose of better illustration only, they are shown in FIG. 2a as spaced layers 37. vividly in order to better recognize the orientation of these layers 37.
  • these annular layers 37 are integrally connected to one another on the outer and on the inner edge of each ring. Apart from the beginning and the end of the hose, there are no free edges in the stack formed by the layers 37 on which the knitted fabric could trickle.
  • a so-called candle 38 is produced from this knitted tube 33, as is shown in longitudinal section in FIG. 2b.
  • the catalyst candle contains two perforated tubes 39 and 40 which are inserted into one another.
  • the tubes 39 and 40 have the same length and are coaxial with one another. They delimit a cylindrical annular space 41 between them. Since they have no other function apart from the support function, the openings contained in the two tubes are as large as possible.
  • Both tubes 39 and 40 are gas-tightly attached at one end to a disk-shaped cover 42.
  • the cover 42 is, for example, welded to the outer tube 40 and to the inner tube 39 and thus closes both the annular space 41 and the interior space formed by the tube 38 in a gas-tight manner.
  • the annular space 41 is the leporello-like knitted tube 33 folded in the longitudinal direction.
  • Its individual layers can be seen in the longitudinal section of FIG. 2b as wavy lines.
  • the individual layers of the layers 37 are shown spaced apart from one another merely for the sake of illustration. In truth they are on top of each other, so with the stratification on average would no longer be visible to the naked eye.
  • the degree of filling of the annular space 41 depends on the required or permissible back pressure that may arise at the catalyst device 9.
  • annular space 41 is closed by an annular disk 43.
  • This disc 43 is welded gas-tight to both the outer tube 40 and the inner tube 39.
  • An opening 44 contained in the disk 43 corresponds in diameter to the inside width of the tube 39.
  • the mode of operation of the catalyst candle 38 shown in FIG. 2b is as follows:
  • the exhaust gas flow passes through the opening 44 into the interior which is kept open by the pipe 38. From here, the exhaust gas stream flows radially through the filter and catalyst body formed by the layers 37 and it emerges on the outside of the tube 40. Since the two pipes are connected to one another both via the ring 43 and via the disk 42, the exhaust gas flow only passes through in this way. It flows approximately parallel to the superimposed layers 37, i.e. approximately in the direction parallel to the alignment of the wales in the individual layers 37.
  • the catalyst device 9 in FIG. 1 is formed by only one catalyst candle 38 according to FIG. 2b.
  • the catalyst candle 38 according to FIG. 2b is used in the exhaust gas duct 3 in such a way that the opening 40
  • FIGS. 3a and 3b Another way of arranging the knitted fabric is shown in FIGS. 3a and 3b.
  • a knitted tube 33 is assumed, which, however, after knitting, is laid flat to form a band 51 which has two layers 52 and 53 connected to one another on the edge.
  • the tape 51 obtained in this way is folded like a leporello, according to FIG. 3b, and a stack 54 is formed which is rectangular in plan and consists of the endless tape 51. It in turn contains several layers 37 lying on top of one another, which are rectangular in plan view. They are shown spaced apart from one another in FIG. 3b only for reasons of illustration. In truth, they are in direct contact.
  • the cage 3b is inserted into a rectangular cage, not shown, which has the task of keeping the stack 54 in shape.
  • the cage corresponds functionally to the two tubes 38 and 39.
  • the cage can therefore be constructed, for example, in such a way that it has two walls of expanded metal which are parallel and spaced apart from one another and which are adjacent to the folded edges of the stack 54. All other walls, however, are closed. The gas flow would then flow through the stack 54 in the direction of an arrow 55.
  • FIG. 4 and 5 finally show, in section and in a top view, a highly schematic view of the atomizing nozzle 39.
  • It contains two channels 56 and 57 which are coaxial with one another and which are each connected individually to the line 28 or 31. At their downstream end, they pass into a nozzle plate 58 in a sealed manner.
  • the nozzle plate 58 contains three bores 59 which are designed in such a way that they converge towards the outlet side.
  • the bores 59 are connected in terms of flow to the channel 57. In this way, three liquid jets are generated which would meet on the central axis of the nozzle plate 58.
  • a plurality of, in total 6, slot-shaped openings 61 which are connected in terms of flow to the channel 46, which coaxially surrounds the inner channel 57 at least in the vicinity of the nozzle plate 58.
  • the slit-shaped openings 61 are arranged in a scale-like manner in the circumferential direction.
  • the mode of operation of the exhaust system 1 shown is as follows:
  • An exhaust gas stream emerges from the cylinders of the diesel engine 1, which contains carbon monoxide, unburned hydrocarbons, soot and nitrogen oxides. All of these components are undesirable.
  • the exhaust gas stream contains unburned air because the diesel engine works with an excess of air corresponding to a ⁇ value between 1.5 and 2.
  • the carbon monoxide and the unburned hydrocarbons react with one another in the catalyst device 9 and they react under the catalytic action of the vanadium pentoxide to form H, O, carbon dioxide and molecular oxygen.
  • the nitrogen oxide would escape from the exhaust system.
  • the urea solution is injected into the exhaust gas stream by means of the liquid pump 17 with the aid of the injection device 5 in the correct mixing ratio and is then atomized with the aid of the compressed air from the slot-shaped nozzles 61.
  • the injected urea solution decomposes to ammonia and carbon dioxide at the high exhaust gas temperature.
  • This ammonia (NH 3 ) reacts under the catalytic action of the vanadium pentoxide to form molecular nitrogen and water.
  • the vanadium pentoxide in the catalyst device 9 also ensures that soot contained in the exhaust gas stream burns flamelessly with the acidic oxygen portion of the air present to form carbon dioxide.
  • the knitted catalyst has the advantage that no urea solution can escape into the open.
  • the "pore structure" of the layered knitted fabric creates such strong eddies that no droplets can get through the catalyst body.
  • the catalyst acts as a trap for the urea solution, which may spread extremely thinly on the surface of the fibers and thus provide a large reaction area for reaction with the harmful nitrogen oxide.
  • urea carbamate as well as other chemical compositions can be used which produce ammonia when heated in the exhaust gas stream. Because of its toxicity, ammonia itself would only be conceivable for stationary systems.
  • An exhaust system that works according to the SCR catalyst principle contains an injection device for a chemical compound that contains ammonia or releases ammonia in the exhaust gas environment.
  • a catalyst arrangement is located downstream of the injection device, in which the substrate for the catalyst is formed by a knitted fabric.
  • the threads of the knitted fabric are coated with the catalyst material, which is preferably vanadium pentoxide.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Analytical Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Biomedical Technology (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

L'invention concerne un système d'échappement (1) fonctionnant selon le principe de la réduction sélective catalytique, qui comprend un dispositif d'injection (5) pour un composé chimique contenant de l'ammoniac ou éliminant de l'ammoniac dans l'environnement des gaz d'échappement. Il est prévu en aval du dispositif d'injection (5) un système de pot catalytique (9) dont le substrat est formé par une structure tricotée. Les fils de cette structure tricotée sont recouverts par le matériau du pot catalytique, de préférence du pentoxyde de vanadium.
PCT/DE1999/002319 1998-07-31 1999-07-30 Systeme d'echappement comportant un dispositif de reduction catalytique de nox et un element support de pot catalytique a base de fibres WO2000008314A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU61876/99A AU6187699A (en) 1998-07-31 1999-07-30 Exhaust system comprising a device for catalytically reducing nox and a catalystsupport body made of fibers

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19834541.0 1998-07-31
DE19834541A DE19834541C2 (de) 1998-07-31 1998-07-31 Abgasanlage

Publications (1)

Publication Number Publication Date
WO2000008314A1 true WO2000008314A1 (fr) 2000-02-17

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PCT/DE1999/002319 WO2000008314A1 (fr) 1998-07-31 1999-07-30 Systeme d'echappement comportant un dispositif de reduction catalytique de nox et un element support de pot catalytique a base de fibres

Country Status (3)

Country Link
AU (1) AU6187699A (fr)
DE (1) DE19834541C2 (fr)
WO (1) WO2000008314A1 (fr)

Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN107109987A (zh) * 2014-11-14 2017-08-29 全耐塑料高级创新研究公司 气体存储结构的制造方法
CN111664717A (zh) * 2020-05-25 2020-09-15 中钢集团天澄环保科技股份有限公司 一种智能型催化脱硝脱co及余热利用一体化装置

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DE10048921A1 (de) * 2000-10-04 2002-04-18 Bosch Gmbh Robert Vorrichtung zur Bildung eines Reduktionsmittel-Abgas-Gemisches und Abgasreinigungsanlage
US6722123B2 (en) 2001-10-17 2004-04-20 Fleetguard, Inc. Exhaust aftertreatment device, including chemical mixing and acoustic effects
US6601385B2 (en) * 2001-10-17 2003-08-05 Fleetguard, Inc. Impactor for selective catalytic reduction system
WO2003054364A2 (fr) * 2001-12-20 2003-07-03 Johnson Matthey Public Limited Company Ameliorations dans la reduction catalytique selective
DE10356997A1 (de) * 2003-12-03 2005-07-07 Helmut Swars Partikelfilter
JP2005180262A (ja) * 2003-12-18 2005-07-07 Tetsuo Toyoda 粒子状物質の減少装置
DE102006024199A1 (de) * 2006-05-23 2007-11-29 Arvinmeritor Emissions Technologies Gmbh Verwirbelungselement für Abgasanlage
DE102010051691A1 (de) * 2010-11-17 2012-05-24 Bayerische Motoren Werke Aktiengesellschaft Abgasanlage

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EP0555746A1 (fr) * 1992-02-10 1993-08-18 Man Nutzfahrzeuge Ag Dispositif pour la réduction catalytique de NOx
EP0558452A1 (fr) * 1992-02-24 1993-09-01 Hans Thomas Hug Purification des effluents gazeux de combustion
WO1994018440A1 (fr) * 1993-02-10 1994-08-18 Alfred Buck Dispositif d'epuration catalytique de gaz en ecoulement, notamment de gaz d'echappement de moteurs a combustion interne
WO1996036797A1 (fr) * 1995-05-19 1996-11-21 Siemens Aktiengesellschaft Chambre de premelange pour installation d'epuration de gaz d'echappement

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DE9308772U1 (de) * 1993-06-12 1993-09-30 Schneider, Arno, Dipl.-Ing., 53343 Wachtberg Vorrichtung zum Betrieb einer Verbrennungsanlage, insbesondere in Form einer Kraft-Wärme-Kopplung oder einer Blockheizkraftwerksanlage mit einer Abgasreinigungsanlage, insbesondere zur Verbrennung von schwerem Heizöl oder von Schweröl

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0555746A1 (fr) * 1992-02-10 1993-08-18 Man Nutzfahrzeuge Ag Dispositif pour la réduction catalytique de NOx
EP0558452A1 (fr) * 1992-02-24 1993-09-01 Hans Thomas Hug Purification des effluents gazeux de combustion
WO1994018440A1 (fr) * 1993-02-10 1994-08-18 Alfred Buck Dispositif d'epuration catalytique de gaz en ecoulement, notamment de gaz d'echappement de moteurs a combustion interne
WO1996036797A1 (fr) * 1995-05-19 1996-11-21 Siemens Aktiengesellschaft Chambre de premelange pour installation d'epuration de gaz d'echappement

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107109987A (zh) * 2014-11-14 2017-08-29 全耐塑料高级创新研究公司 气体存储结构的制造方法
CN111664717A (zh) * 2020-05-25 2020-09-15 中钢集团天澄环保科技股份有限公司 一种智能型催化脱硝脱co及余热利用一体化装置
CN111664717B (zh) * 2020-05-25 2022-07-01 中钢集团天澄环保科技股份有限公司 一种智能型催化脱硝脱co及余热利用一体化装置

Also Published As

Publication number Publication date
DE19834541A1 (de) 2000-02-03
DE19834541C2 (de) 2001-08-09
AU6187699A (en) 2000-02-28

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