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EP1092846B1 - Hydrodynamically optimized catalytic body - Google Patents

Hydrodynamically optimized catalytic body Download PDF

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Publication number
EP1092846B1
EP1092846B1 EP00121383A EP00121383A EP1092846B1 EP 1092846 B1 EP1092846 B1 EP 1092846B1 EP 00121383 A EP00121383 A EP 00121383A EP 00121383 A EP00121383 A EP 00121383A EP 1092846 B1 EP1092846 B1 EP 1092846B1
Authority
EP
European Patent Office
Prior art keywords
catalytic
catalytic structure
shaped
shaped catalytic
molded body
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
EP00121383A
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German (de)
French (fr)
Other versions
EP1092846A3 (en
EP1092846A2 (en
Inventor
Michael Bender
Andreas Wölfert
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BASF SE
Original Assignee
BASF SE
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Publication date
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Publication of EP1092846A2 publication Critical patent/EP1092846A2/en
Publication of EP1092846A3 publication Critical patent/EP1092846A3/en
Application granted granted Critical
Publication of EP1092846B1 publication Critical patent/EP1092846B1/en
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10Exhaust 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
    • F01N3/24Exhaust 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
    • F01N3/28Construction of catalytic reactors
    • F01N3/2803Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • F01N3/2807Metal other than sintered metal
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10Exhaust 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
    • F01N3/24Exhaust 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
    • F01N3/28Construction of catalytic reactors
    • F01N3/2803Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2470/00Structure or shape of gas passages, pipes or tubes
    • F01N2470/18Structure or shape of gas passages, pipes or tubes the axis of inlet or outlet tubes being other than the longitudinal axis of apparatus

Definitions

  • the invention relates to a catalytic molded body with an upstream side and a downstream surface, as well as a peripheral surface.
  • a purification of the exhaust gas is carried out with the aid of a catalyst.
  • the exhaust gas stream is passed through a arranged in the exhaust line of the motor vehicle catalytic moldings.
  • a shaped body usually has a multiplicity of channel-like structures which are arranged parallel to the axis of the catalytic shaped body.
  • the customary catalytic shaped bodies are constructed either from ceramic materials or from metal.
  • the material can either be catalytically active itself or the walls of the channels can be coated with a catalytically active material, usually metals, such as platinum, vanadium, cobalt, nickel, chromium, etc.
  • the catalytic molded body is arranged in the installed state in a housing in the exhaust system of a motor vehicle. During operation, the catalytic molded body is flowed against the exhaust gas at an end face. In this case, the total gas stream is divided into a plurality of individual gas streams, which are passed through the channel-like structures and reunite at the downstream surface of the catalytic molded body. The exchange between the individual gas streams is limited by the at least partially, in extreme cases completely gastight walls of the channels.
  • the cross-sectional area of the catalytic shaped body is generally larger than that of the pipe through which the exhaust gas flow from the engine is supplied to the catalyst.
  • the cross-section of the exhaust gas stream at the entrance is widened drastically and reduced again at the exit. This results in a lateral pressure gradient at the upstream end surface of the molded body, which is in the order of magnitude of the pressure drop over the molded body and thereby to a radial distribution of the gas velocities in the channel-like structures.
  • different flow rates and thus different hydrodynamic residence times occur in the independently flowed through channel-like structures.
  • a catalyst muffler is described, with a Muffler housing and a catalyst disposed therein. Before the inflow side of Catalyst is arranged a plurality of exhaust manifold plates, which by a Inlet into the muffler exhaust gas flowed evenly into the Distributed exhaust gas passages of the catalyst.
  • the molding should be designed so that the flow resistance the individual to be flowed through channel-like structures varies radially. This will the flow resistance is reduced in the direction of the lateral pressure loss, so that over the entire cross-section of the molding a uniform flow velocity is achieved.
  • the same effect can be achieved by varying the channel length.
  • This Preferably takes place in that the shaped body along its axis a larger Has extension than in the longitudinal direction along its peripheral surface.
  • DE 22 01 881 is a one-piece carrier body with described continuous channels for catalysts, wherein the carrier body at least at a lying in the flow path of the gas cone-like or is formed pyramid-shaped. This conical or pyramidal section of the Carrier body is preferably arranged on the upstream side.
  • EP 0 818 613 also teaches a catalyst device for purifying exhaust gases.
  • This consists of a tubular housing extending at both ends tapered frusto-conical.
  • a catalytic molded body is provided, wherein the exhaust gas flowed end face has a convex curvature. Together with the truncated cone-like portion of the housing so that a more even distribution of flow velocity across the cross section be achieved.
  • a catalyst carrier body which is a has improved heat radiation behavior from the individual layers of the matrix.
  • the catalyst carrier body on the downstream side of a Has projection.
  • the projection can be shaped differently. It will proposed to design the projection conical or frustoconical or that the projecting shape through a substantially inwardly from the periphery of the matrix extending, at least partially convex curvature is formed. By the projecting shape, the area is increased, the heat radiation and thus the Heat transfer to the effluent exhaust gas is available.
  • DE 22 01 881 discloses a catalyst compound coated with Carrier body, which at least one in the flow path the gas lying side cone-like or pyramidal is trained.
  • the object of the invention is therefore to provide a catalytic molded body, which allows a better homogenization of the flow.
  • This object is achieved by a catalytic molded body with an upstream and a downstream surface achieved in that the antröm bathe surface as a lateral surface a conical or truncated cone-like projection is formed, wherein the lateral surface at least partially has a concave curvature.
  • the upstream surface By designing the upstream surface in such a way that the upstream surface is formed as a lateral surface of a conical or truncated cone-like projection, wherein the lateral surface at least partially has a concave curvature, a Compared to the known from the prior art designs of on the upstream surface much more homogeneous flow distribution can be achieved. Due to its uniform flow shows the inventive catalytic Shaped body better effectiveness and a longer shelf life, since no or at least a much lower premature deactivation of the catalyst in particular heavily loaded areas occurs.
  • the concave curvature of the upstream surface extends from the circumference of the catalytic shaped body towards the axis lying in the flow direction.
  • the lead ideally runs in a tip. However, there are high mechanical loads in this area The tip can also be cut off.
  • the lead then receives one frustoconical shape.
  • the truncated cone may be rounded on the inflow side. This will achieved when the lateral surface has a convex curvature in sections.
  • the curved end face can be designed this is evident when looking at a longitudinal section through the catalytic molded body composed of linear sections, with two adjacent linear sections respectively enclose an angle with each other.
  • the inflow-side surface at wound catalytic shaped bodies to be stepped. In this case, then the Enveloping the lateral surface of a concave curvature. Especially good results in the homogeneity distribution of the flow, however, are obtained when the Curvature of the upstream surface is smooth.
  • the inflow-side end face with the invention To design curvature.
  • downstream surface of the catalytic shaped body curved form. This can be an even finer vote of the Homogeneity profiles can be achieved over the cross section of the catalytic shaped body.
  • the catalytic molded body is designed in such a way that the catalytic shaped body is designed as a monolith.
  • the catalytic shaped body may be constructed of a catalytically active material. This is possible, for example, by design as a metal catalyst.
  • the catalytic molded body is parallel to Traversed longitudinal axis of the catalytic molded body extending channels whose Walls are preferably coated with a catalytically active material.
  • a further improvement of the flow profile over the cross section of the catalytic Shaped body can be achieved if a housing for receiving the catalytic Shaped body is provided, with a tubular portion at its ends cone-shaped sections are formed.
  • the truncated cone-like sections represent the Transition between the coming of the engine exhaust pipe, which a small Diameter, to the tubular portion of the catalyst housing ago.
  • the slope of the truncated cone can be the flow profile over the cross section of the influence catalytic shaped body.
  • the cone-shaped sections on the on the upstream side or at the downstream end of the catalyst housing different Have slopes.
  • the erfindunshiele catalytic molded body is particularly suitable for the purification of Material flows, in particular exhaust gas streams of internal combustion engines.
  • FIG. 1 shows a longitudinal section through a catalytic molded body according to the invention 1.
  • the catalytic molded body 1 is traversed by exhaust gas in the direction of arrow 2. It has an upstream surface 3, a downstream surface 4 and a Peripheral surface 5 on.
  • the catalytic shaped body may be of (not shown) Channels to be traversed, which extend in the direction of the longitudinal axis 6 of the shaped body 1.
  • the upstream surface 3 of the catalytic molded body 1 is curved, wherein the line which in longitudinal section between the axis 6 of the shaped body and the Circumferential surface 5 extends, having a concave curvature.
  • the catalytic shaped body 1 therefore forms a cone 7 towards the inflow side, whose lateral surface 8 is a concave one Curvature has.
  • the cone 7 runs in a tip 9 out. This is exposed to high mechanical loads during operation of the catalyst. It is therefore also possible to form the cone 7 as a truncated cone or the tip of the 9th To round off, to achieve increased mechanical stability.
  • This embodiment is shown by the dashed line 15.
  • the downstream surface 4 of the catalytic molded body 1 is designed planar in the illustrated embodiment.
  • the catalytic molded body may be made of a ceramic material, or also be designed as a metal catalyst.
  • the catalytic molded body 1 is in a housing 10, for example made of stainless steel exists, installed.
  • the housing 10 comprises a tubular portion 11, whose Inner diameter of the maximum outer diameter of the catalytic molded body. 1 corresponds, so that the inflowing exhaust gas forcibly the catalytic molded body. 1 must flow through.
  • each cone-shaped portions 12a, 12b Close at the two ends of the tubular portion 11 each cone-shaped portions 12a, 12b. Through these conical sections 12a, 12b, the expansion or reduction of the diameter of the incoming and outgoing takes place Exhaust pipes 13a, 13b on the diameter of the catalytic molded body 1.
  • the slope the cone-shaped portion is chosen to be larger in magnitude on the upstream side than on the downstream side.
  • the installation of the catalytic molded body 1 in the housing 10th takes place in the manner that the cone 7 of the catalytic molded body 1 in the cone-shaped portion 12a of the housing 10 protrudes.
  • FIG. 2 shows longitudinal sections through different catalytic molded bodies 1, each incorporated in a housing 10. For the sake of simplicity, only the shown upper halves of the catalyst device. The illustration is schematic and does not correspond to a real version on a scale.
  • the four illustrated catalytic bodies each have a circular shape Cross-section on. They differ by the design of the upstream or downstream face.
  • the catalytic shaped bodies correspond to the Representations 2a to c embodiments of the prior art.
  • Figure 2d shows a Embodiment of the catalytic molded body according to the invention.
  • FIG. 2e shows a special embodiment of the lateral surface of the catalytic according to the invention Molding.
  • FIG. 2 a shows a catalytic molded body whose end faces are located both on the On the inflow side are designed as planar on the downstream side.
  • FIG. 2b shows a catalytic shaped body whose upstream surface is conical, wherein the lateral surface of the cone has no curvature. The downstream end surface is planar.
  • Figure 2c shows a catalytic shaped body in which both the on the inflow side, as well as the downstream surface is designed as a jacket of a cone. Again, the lateral surface has no curvature.
  • Figure 2d corresponds to one Embodiment of the catalytic molded body according to the invention.
  • the end face is designed as a lateral surface of a cone, wherein the Lateral surface has a concave curvature in the direction of the longitudinal axis of the catalytic Having molded body.
  • a monolithic honeycomb shaped body made of copper-spinel active material was installed in each case in a housing.
  • the moldings produced correspond in their longitudinal section to the illustrations in FIGS. 2a to d.
  • the maximum diameter of the monoliths was 13.2 cm in each case, the longitudinal extent was 15.2 cm in the embodiment according to FIG. 2a.
  • embodiments b to d the longitudinal extent in the constant diameter section of the embodiment of Figure 2a.
  • Each of the four monoliths a to d were crossed by the same number of square longitudinal channels of equal lateral dimensions (400 cpsi, 7.2 mils).
  • the monoliths were each installed in the same housing and measured in a test apparatus.
  • the monolith to be tested was in each case subjected to a gas flow in such a way that resulted in a gas load of 90 000 h -1 .
  • Atmospheric air was used as the test gas.
  • the temperature of the gas stream was 450 ° C, which corresponds to a value characteristic of exhaust gas temperatures.
  • the flow rates were measured on the downstream side.
  • the measurement results are shown in FIG.
  • the normalized teaching tube velocity (y) is recorded against the radius (x).
  • Figure 2e shows schematically an embodiment of the upstream face, as e.g. occurs in wound catalysts.
  • the steps 16 are like this formed that the envelope, in longitudinal section through the dashed line 17th is shown having a concave curvature.
  • Figure 4 shows schematically cross sections through different housing shapes for catalytic shaped bodies.
  • the inflow-side surface according to the invention as a lateral surface of a executed symmetrical cone or truncated cone.
  • the longitudinal axis 14 drops the feeding exhaust pipe not with the longitudinal axis 6 of the catalytic shaped body together.
  • the inflow-side surface is as a lateral surface of a unbalanced cone or truncated cone according to the teaching of the invention perform.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The catalytic body has an inflow surface (3) and outflow surface (4). The inflow surface is formed as a sleeve surface (8) of a conical or frusto-conical projection (7) with a concave curvature at least in some sections. The curvature of the inflow surface can be smooth. The outflow surface can be planar or can be curved. The catalytic body can be a monolith. The catalytic body can be made from several superposed layers of a structured surface material

Description

Die Erfindung betrifft einen katalytischen Formkörper mit einer anströmseitigen und einer abströmseitigen Fläche, sowie eine Umfangsfläche.The invention relates to a catalytic molded body with an upstream side and a downstream surface, as well as a peripheral surface.

Um gesetzlichen Vorschriften zu genügen, die eine weitgehende Befreiung der Abgasströme von Kraftfahrzeugen von umweltschädlichen Substanzen, wie Stickoxiden oder aromatischen Kohlenwasserstoffen fordern, wird eine Reinigung des Abgases mit Hilfe eines Katalysators vorgenommen. Dabei wird der Abgasstrom durch einen im Abgasstrang des Kraftfahrzeugs angeordneten katalytischen Formkörper geleitet. Ein solcher Formkörper weist üblicherweise eine Vielzahl von kanalartigen Strukturen auf, die parallel zur Achse des katalytischen Formkörpers angeordnet sind. Die gebräuchlichen katalytischen Formkörper sind entweder aus keramischen Werkstoffen oder aus Metall aufgebaut. Das Material kann dabei entweder selbst katalytisch aktiv sein oder die Wandungen der Kanäle können mit einem katalytisch aktiven Material, meist Metallen, wie Platin, Vanadium, Kobalt, Nickel, Chrom etc. beschichtet sein. Der katalytische Formkörper ist im eingebauten Zustand in einem Gehäuse im Abgasstrang eines Kraftfahrzeugs angeordnet. Während des Betriebs wird der katalytische Formkörper an einer Stirnfläche vom Abgas angeströmt. Dabei teilt sich der Gesamtgasstrom in eine Vielzahl einzelner Gasströme auf, die durch die kanalartigen Strukturen geleitet werden und sich an der abströmseitigen Fläche des katalytischen Formkörpers wieder vereinigen. Der Austausch zwischen den einzelnen Gasströmen ist durch die mindestens teilweise, in Extremfällen vollständig gasdichten Wände der Kanäle eingeschränkt.
Die Querschnittsfläche des katalytischen Formkörpers ist im Allgemeinen größer als die des Rohres, durch das der Abgasstrom vom Motor kommend dem Katalysator zugeführt wird. Durch das Gehäuse, in dem der katalytische Formkörper eingebaut ist, wird der Querschnitt des Abgasstromes am Eingang drastisch aufgeweitet und am Ausgang wieder reduziert. Hierdurch kommt es zu einem lateralen Druckgradienten an der anströmseitigen Stirnfläche des Formkörpers, der in der Größenordnung des Druckverlustes über dem Formkörper liegt und dadurch zu einer radialen Verteilung der Gasgeschwindigkeiten in den kanalartigen Strukturen. Es stellen sich also in den unabhängig durchströmten kanalartigen Strukturen unterschiedliche Strömungsgeschwindigkeit und damit unterschiedliche hydrodynamische Verweilzeiten ein. In der Mitte einer keramischen Wabe in einem Abgaskatalysator für ein Automobil herrschen normalerweise hohe Strömungsgeschwindigkeiten, am Rand strömt das Gas dagegen nur langsam durch die Wabe. Diese ungleichmäßige Verteilung bewirkt Einbußen der Wirksamkeit des Formkörpers bei der katalytischen Reinigung des Abgasstromes. Um eine bessere Reinigungswirkung zu erhalten, ist daher eine gleichmäßigere Anströmung des Formkörpers erwünscht. Um diese Schwierigkeit zu überwinden, sind verschiedene Lösungsvorschläge beschrieben worden.
In order to comply with legal requirements that require a substantial exemption of the exhaust gas streams of motor vehicles from environmentally harmful substances such as nitrogen oxides or aromatic hydrocarbons, a purification of the exhaust gas is carried out with the aid of a catalyst. In this case, the exhaust gas stream is passed through a arranged in the exhaust line of the motor vehicle catalytic moldings. Such a shaped body usually has a multiplicity of channel-like structures which are arranged parallel to the axis of the catalytic shaped body. The customary catalytic shaped bodies are constructed either from ceramic materials or from metal. The material can either be catalytically active itself or the walls of the channels can be coated with a catalytically active material, usually metals, such as platinum, vanadium, cobalt, nickel, chromium, etc. The catalytic molded body is arranged in the installed state in a housing in the exhaust system of a motor vehicle. During operation, the catalytic molded body is flowed against the exhaust gas at an end face. In this case, the total gas stream is divided into a plurality of individual gas streams, which are passed through the channel-like structures and reunite at the downstream surface of the catalytic molded body. The exchange between the individual gas streams is limited by the at least partially, in extreme cases completely gastight walls of the channels.
The cross-sectional area of the catalytic shaped body is generally larger than that of the pipe through which the exhaust gas flow from the engine is supplied to the catalyst. Through the housing in which the catalytic molded body is installed, the cross-section of the exhaust gas stream at the entrance is widened drastically and reduced again at the exit. This results in a lateral pressure gradient at the upstream end surface of the molded body, which is in the order of magnitude of the pressure drop over the molded body and thereby to a radial distribution of the gas velocities in the channel-like structures. Thus, different flow rates and thus different hydrodynamic residence times occur in the independently flowed through channel-like structures. In the middle of a ceramic honeycomb in an exhaust gas catalytic converter for an automobile normally prevail high flow velocities, on the edge, however, the gas flows only slowly through the honeycomb. This uneven distribution causes loss of effectiveness of the shaped body in the catalytic purification of the exhaust gas stream. In order to obtain a better cleaning effect, therefore, a more uniform flow of the shaped body is desired. To overcome this difficulty, various solutions have been described.

In T. Hauber, P. Zacke, J. Braun, D. Ueberschär, Soc. Automot. Eng. Paper # 98 04 24 wird beschrieben, daß sich die Anströmung eines Formkörpers durch die Verlängerung des Zulauftrichters und des Ablauftrichters verbessern läßt. Für die technische Nutzung des Wabenkörpers ist dies jedoch nachteilhaft, da sich dadurch die geometrische Länge des Katalysatorgehäuses verlängert und tolerable Grenzen rasch überschritten werden.In T. Hauber, P. Zacke, J. Braun, D. Ueberschar, Soc. Automot. Closely. Paper # 98 04 24 is described that the flow of a shaped body by the extension of the Improve inlet funnel and the funnel. For the technical use of the However, this is disadvantageous because this results in the geometric length of the honeycomb body Catalyst housing extended and tolerable limits are exceeded quickly.

Als Alternative wurde zur Optimierung der Anströmung des Formkörpers vorgeschlagen, zusätzliche technische Vorrichtungen in dem Zuströmtrichter einzubauen, die durch Zwangskräfte den Gasstrom umlenken und dadurch die Anströmung des Wabenkörpers vergleichmäßigen.As an alternative, it has been proposed to optimize the flow of the molding, to install additional technical devices in the inlet funnel through Forcing forces deflect the gas flow and thereby the flow of the honeycomb body equalize.

So wird in der DE 36 27 637 A1 ein Katalysatorauspufftopf beschrieben, mit einem Auspufftopfgehäuse und einem darin angeordneten Katalysator. Vor der Anströmseite des Katalysators ist eine Mehrzahl von Abgasverteilerplatten angeordnet, die das durch einen Einlaß in das Auspufftopfgehäuse eingeströmte Abgas gleichmäßig in die Abgasdurchgänge des Katalysators verteilt.Thus, in DE 36 27 637 A1 a catalyst muffler is described, with a Muffler housing and a catalyst disposed therein. Before the inflow side of Catalyst is arranged a plurality of exhaust manifold plates, which by a Inlet into the muffler exhaust gas flowed evenly into the Distributed exhaust gas passages of the catalyst.

In der US 3,964,875 wird ein Katalysatorsystem zur Reinigung von Autoabgasen mit einem Gehäuse und einem darin angeordneten katalytischen Formkörper beschrieben. Auf der Anströmseite ist am Eingang des Gehäuses ein Deflektor in Form eines Flügelrades angeordnet, durch das das einströmende Abgas einen Drall erhält und radial nach außen verteilt wird. Dadurch soll eine gleichmäßigere Anströmung der Stirnseite des katalytischen Formkörpers erreicht werden.In US 3,964,875 a catalyst system for the purification of automobile exhaust gases with a housing and a catalytic molded body disposed therein. On the inflow side is at the entrance of the housing a deflector in the form of an impeller arranged, through which the incoming exhaust gas receives a twist and radially outward is distributed. This is intended to provide a more uniform flow to the front of the can be achieved catalytic shaped body.

Nachteil derartiger zusätzlicher Einbauten ist jedoch die erhöhte Wärmekapazität des Katalysatorsystems. Durch die Aufheizung der Einbauten wird dem Abgasstrom zusätzlich Wärme entzogen, die für die Aufheizung des katalytischen Formkörpers auf Temperaturen katalytischer Aktivitäten benötigt wird. Dies senkt die Reinigungskapazität derartiger Katalysatorsysteme in der Aufwärmphase drastisch.However, the disadvantage of such additional installations is the increased heat capacity of the Catalyst system. By heating the internals is the exhaust gas flow in addition Heat extracted for heating the catalytic shaped body to temperatures catalytic activities is needed. This reduces the cleaning capacity of such Catalyst systems in the warm-up phase drastically.

Ein weiterer Nachteil dieser Einbauten liegt in ihrer geringen mechanischen Stabilität. Die Einbauten sind im Abgasstrang eines Fahrzeugs durch Schallwellen starken Deformationskräften ausgesetzt und daher anfällig gegen mechanische Beschädigung. Derartige Beschädigungen wirken sich nachteilig auf die Lebensdauer der Katalysatoren selbst, des Motors und seiner Bestandteile aus.Another disadvantage of these installations is their low mechanical stability. The Installations are strong in the exhaust system of a vehicle due to sound waves Exposed to deformation forces and therefore prone to mechanical damage. Such damage has a detrimental effect on the life of the catalysts itself, the engine and its components.

Als weitere Möglichkeit wurde vorgeschlagen, die Form des Formkörpers selbst zu modifizieren. Dabei soll der Formkörper so gestaltet sein, daß der Strömungswiderstand der einzelnen zu durchströmenden kanalartigen Strukturen radial variiert. Dadurch wird der Strömungswiderstand in Richtung des lateralen Druckverlustes verringert, so daß über den gesamten Querschnitt des Formkörpers eine gleichmäßige Strömungsgeschwindigkeit erzielt wird.As another possibility, it has been proposed to change the shape of the molding itself modify. In this case, the molding should be designed so that the flow resistance the individual to be flowed through channel-like structures varies radially. This will the flow resistance is reduced in the direction of the lateral pressure loss, so that over the entire cross-section of the molding a uniform flow velocity is achieved.

In der DE 43 39 447 A1 wird vorgeschlagen, durch Veränderung der Kanaldichte den Strömungswiderstand zu variieren. Dazu wird ein gekrümmter Wabenkörper vorgeschlagen, der eine Anzahl an Durchgangsöffnungen aufweist, die sich durch diesen längs einer Richtung, in der der Wabenkörper gekrümmt ist, erstrecken. Die Abstände zwischen den inneren Trennwänden, die die Durchgangsöffnungen definieren, sind auf einer radial außenliegenden Seite eines gekrümmten Abschnittes größer festgelegt als auf einer radial innenliegenden Seite davon. Dadurch ergibt sich, daß der Querschnitt der radial außenliegenden Durchgangsöffnungen geringer ist als der Querschnitt der in radialer Richtung innenliegenden Durchgangsöffnungen. Dadurch ist der Strömungswiderstand, der in radialer Richtung außenliegenden Durchtrittsöffnungen mit geringerer Querschnittsfläche größer als der der radial innenliegenden Durchgangsöffnungen mit größerer Querschnittsfläche.In DE 43 39 447 A1 it is proposed by changing the channel density the To vary flow resistance. This is a curved honeycomb body proposed, which has a number of through holes extending through this along a direction in which the honeycomb body is curved extend. The distances between the inner partitions that define the passage openings are on a radially outer side of a curved portion set larger than on a radially inner side thereof. This results in that the cross section of the radially outer through holes is less than the cross section in the radial Direction inside through holes. This is the flow resistance, the radially outer passage openings with less Cross-sectional area greater than that of the radially inner through holes with larger cross-sectional area.

Dieselbe Wirkung kann durch eine Variation der Kanallänge erreicht werden. Dies geschieht vorzugsweise dadurch, daß der Formkörper entlang seiner Achse eine größere Ausdehnung aufweist als in Längsrichtung entlang seiner Umfangsfläche.The same effect can be achieved by varying the channel length. This Preferably takes place in that the shaped body along its axis a larger Has extension than in the longitudinal direction along its peripheral surface.

In der DE 22 01 881 wird ein aus einem Stück bestehender Trägerkörper mit durchgehenden Kanälen für Katalysatoren beschrieben, wobei der Trägerkörper mindestens an einer in der Strömungsbahn des Gases liegenden Seite konusartig oder pyramidenförmig ausgebildet ist. Dieser konusartige oder pyramidenförmige Abschnitt des Trägerkörpers ist vorzugsweise auf der Anströmseite angeordnet.In DE 22 01 881 is a one-piece carrier body with described continuous channels for catalysts, wherein the carrier body at least at a lying in the flow path of the gas cone-like or is formed pyramid-shaped. This conical or pyramidal section of the Carrier body is preferably arranged on the upstream side.

Ein vergleichbarer Weg wird mit der Lehre der DE 24 28 964 beschritten. Dort wird ein Katalysatorsystem beschrieben mit einem Gehäuse und einem darin angeordneten längs durchströmbaren katalytischen Formkörper. Der katalytische Formkörper ist zur Längsachse hin länger als in den Randbereichen, so daß im Bereich der größeren Strömungsenergie durch entsprechende Vergrößerung der Einsatzdurchstromlänge in der Strömungsmitte ein größerer Strömungswiderstand und damit eine gleichmäßigere Durchströmung über den ganzen Einsatzquerschnitt erreichbar ist.A comparable way is taken with the teaching of DE 24 28 964. There will be one Catalyst system described with a housing and disposed therein longitudinally permeable catalytic shaped body. The catalytic molded body is for Longitudinal axis longer than in the edge regions, so that in the area of the larger Flow energy by corresponding increase in Einsatzdurchstromlänge in the Flow center a greater flow resistance and thus a more uniform Flow through the entire cross section can be achieved.

Die EP 0 818 613 lehrt ebenfalls eine Katalysatorvorrichtung zum Reinigen von Abgasen. Diese besteht aus einem rohrförmigen Gehäuse, das sich an seinen beiden Enden kegelstumpfförmig verjüngt. Im Gehäuse ist ein katalytischer Formkörper vorgesehen, wobei die vom Abgas angeströmte Stirnfläche eine konvexe Krümmung aufweist. Zusammen mit dem kegelstumpfartigen Abschnitt des Gehäuses soll damit eine gleichmäßigere Verteilung der Strömungsgeschwindigkeit über den Querschnitt hinweg erreicht werden.EP 0 818 613 also teaches a catalyst device for purifying exhaust gases. This consists of a tubular housing extending at both ends tapered frusto-conical. In the housing, a catalytic molded body is provided, wherein the exhaust gas flowed end face has a convex curvature. Together with the truncated cone-like portion of the housing so that a more even distribution of flow velocity across the cross section be achieved.

In der DE 197 49 379 wird ein Katalysator-Trägerkörper beschrieben, welcher ein verbessertes Wärmeabstrahlungsverhalten von den einzelnen Lagen der Matrix aufweist. Dazu ist vorgesehen, daß der Katalysator-Trägerkörper auf der Abströmseite einen Vorsprung aufweist. Der Vorsprung kann verschieden geformt sein. Es wird vorgeschlagen, den Vorsprung kegelig oder kegelstumpfförmig auszugestalten oder daß die vorspringende Form durch eine im wesentlichen vom Umfang der Matrix nach innen verlaufende, zumindest abschnittsweise konvexe Krümmung gebildet ist. Durch die vorspringende Form wird die Fläche vergrößert, die zur Wärmeabstrahlung und damit zur Wärmeübertragung auf das abströmende Abgas zur Verfügung steht.In DE 197 49 379 a catalyst carrier body is described, which is a has improved heat radiation behavior from the individual layers of the matrix. For this purpose, it is provided that the catalyst carrier body on the downstream side of a Has projection. The projection can be shaped differently. It will proposed to design the projection conical or frustoconical or that the projecting shape through a substantially inwardly from the periphery of the matrix extending, at least partially convex curvature is formed. By the projecting shape, the area is increased, the heat radiation and thus the Heat transfer to the effluent exhaust gas is available.

Die DE 22 01 881 offenbart einen mit Katalysatormasse überzogenen Trägerkörper, der an mindestens einer in der Strömungsbahn des Gases liegenden Seite konusartig oder pyramidenförmig ausgebildet ist.DE 22 01 881 discloses a catalyst compound coated with Carrier body, which at least one in the flow path the gas lying side cone-like or pyramidal is trained.

Obwohl mit den aus dem Stand der Technik bekannten Ausgestaltungen der anströmseitigen Stirnfläche des katalytischen Formköpers ein merklich gleichmäßigeres Strömungsprofil über den Querschnitt hinweg erreicht werden kann, läßt sich doch keine homogene Geschwindigkeitsverteilung verwirklichen. Although with the known from the prior art embodiments of upstream face of the catalytic mold a noticeably more uniform Flow profile can be achieved across the cross section, but can not be realize homogeneous velocity distribution.

Aufgabe der Erfindung ist daher, einen katalytischen Formkörper zur Verfügung zu stellen, der eine bessere Homogenisierung der Anströmung ermöglicht.The object of the invention is therefore to provide a catalytic molded body, which allows a better homogenization of the flow.

Diese Aufgabe wird durch einen katalytischen Formkörper mit einer anströmseitigen und einer abströmseitigen Fläche dadurch gelöst, daß die antrömseitige Fläche als Mantelfläche eines kegel- oder kegelstumpfartigen Vorsprungs ausgebildet ist, wobei die Mantelfläche zumindest abschnittsweise eine konkave Krümmung aufweist.This object is achieved by a catalytic molded body with an upstream and a downstream surface achieved in that the antrömseitige surface as a lateral surface a conical or truncated cone-like projection is formed, wherein the lateral surface at least partially has a concave curvature.

Indem die anströmseitige Fläche in der Weise gestaltet wird, daß die anstromseitige Fläche als Mantelfläche eines kegel- oder kegelstumpfartigen Vorsprungs ausgebildet ist, wobei die Mantelfläche zumindest abschnittsweise eine konkave Krümmung aufweist, kann eine im Vergleich zu den aus dem Stand der Technik bekannten Gestaltungen der anströmseitigen Fläche wesentlich homogenere Strömungsverteilung erreicht werden. Durch seine gleichmäßige Durchströmung zeigt der erfindungsgemäße katalytische Formkörper eine bessere Wirksamkeit sowie eine längere Haltbarkeit, da keine bzw. zumindest eine deutlich geringere vorzeitige Deaktivierung des Katalysators in besonders stark belasteten Bereichen auftritt.By designing the upstream surface in such a way that the upstream surface is formed as a lateral surface of a conical or truncated cone-like projection, wherein the lateral surface at least partially has a concave curvature, a Compared to the known from the prior art designs of on the upstream surface much more homogeneous flow distribution can be achieved. Due to its uniform flow shows the inventive catalytic Shaped body better effectiveness and a longer shelf life, since no or at least a much lower premature deactivation of the catalyst in particular heavily loaded areas occurs.

Die konkave Krümmung der anströmseitigen Fläche verläuft vom Umfang des katalytischen Formkörpers zur in Durchströmrichtung liegenden Achse hin. Der Vorsprung läuft ideal in eine Spitze aus. Da in diesem Bereich jedoch hohe mechanische Belastungen auftreten, kann die Spitze auch gekappt sein. Der Vorsprung erhält dann eine kegelstumpfartige Form. Der Kegelstumpf kann anströmseitig abgerundet sein. Dies wird erreicht, wenn die Mantelfläche abschnittsweise eine konvexe Krümmung aufweist.The concave curvature of the upstream surface extends from the circumference of the catalytic shaped body towards the axis lying in the flow direction. The lead ideally runs in a tip. However, there are high mechanical loads in this area The tip can also be cut off. The lead then receives one frustoconical shape. The truncated cone may be rounded on the inflow side. this will achieved when the lateral surface has a convex curvature in sections.

Aus produktionstechnischen Gründen kann die gekrümmte Stirnfläche so gestaltet werden, das es sich bei Betrachtung eines Längsschnittes durch den katalytischen Formkörper aus linearen Abschnitten zusammensetzt, wobei zwei benachbarte lineare Abschnitte jeweils einen Winkel miteinander einschließen. Ebenso kann die anströmseitige Fläche bei gewickelten katalytischen Formkörpern gestuft sein. In diesem Fall weist dann die Umhüllende der Mantelfläche eine konkave Krümmung auf. Besonders gute Ergebnisse bei der Homogenitätsverteilung der Strömung werden jedoch erhalten, wenn die Krümmung der anströmseitigen Fläche glatt ist.For technical production reasons, the curved end face can be designed this is evident when looking at a longitudinal section through the catalytic molded body composed of linear sections, with two adjacent linear sections respectively enclose an angle with each other. Likewise, the inflow-side surface at wound catalytic shaped bodies to be stepped. In this case, then the Enveloping the lateral surface of a concave curvature. Especially good results in the homogeneity distribution of the flow, however, are obtained when the Curvature of the upstream surface is smooth.

Im allgemeinen reicht es aus, die anströmsseitige Stirnfläche mit der erfindungsgemäßen Krümmung auszugestalten. In diesem Fall kann die abströmseitige Fläche des katalytischen Formkörpers planar ausgebildet sein. Dadurch können Kosteneinsparungen bei der Herstellung des katalytischen Formkörpers erreicht werden.In general, it is sufficient, the inflow-side end face with the invention To design curvature. In this case, the downstream surface of the be formed planar catalytic body. This can save costs be achieved in the preparation of the catalytic molded body.

Es ist jedoch auch möglich, die abströmsseitige Fläche des katalytischen Formkörpers gekrümmt auszubilden. Dadurch kann eine noch feinere Abstimmung des Homogenitätsprofils über den Querschnitt des katalytischen Formkörpers erreicht werden.However, it is also possible, the downstream surface of the catalytic shaped body curved form. This can be an even finer vote of the Homogeneity profiles can be achieved over the cross section of the catalytic shaped body.

Im allgemeinen wird der katalytische Formkörper in der Weise gestaltet, daß der katalytische Formkörper als Monolith ausgebildet ist.In general, the catalytic molded body is designed in such a way that the catalytic shaped body is designed as a monolith.

Es ist jedoch auch möglich, den katalytischen Formkörper in der Weise auszugestalten, daß der katalytische Formkörper aus einer Vielzahl übereinander angeordneten Lagen eines strukturierten flächigen Materials aufgebaut ist.However, it is also possible to design the catalytic molded body in such a way that the catalytic molded body of a plurality of superimposed layers of a structured flat material is constructed.

Der katalytische Formkörper kann aus einem katalytisch aktiven Material aufgebaut sein. Dies ist beispielsweise durch Ausgestaltung als Metallkatalysator möglich.The catalytic shaped body may be constructed of a catalytically active material. This is possible, for example, by design as a metal catalyst.

Bei einer anderen Ausführungsform wird der katalytische Formkörper von parallel zur Längsachse des katalytischen Formkörpers verlaufenden Kanälen durchzogen, deren Wandungen vorzugsweise mit einem katalytisch aktiven Material beschichtet sind.In another embodiment, the catalytic molded body is parallel to Traversed longitudinal axis of the catalytic molded body extending channels whose Walls are preferably coated with a catalytically active material.

Eine weitere Verbesserung des Strömungsprofils über den Querschnitt des katalytischen Formkörpers läßt sich erreichen, wenn ein Gehäuse zur Aufnahme des katalytischen Formkörpers vorgesehen ist, mit einem rohrförmigen Abschnitt, an dessen Enden konusförmige Abschnitte angeformt sind. Die kegelstumpfartigen Abschnitte stellen den Übergang zwischen dem vom Motor kommenden Abgasrohr, welches einen geringen Durchmesser aufweist, zum rohrförmigen Abschnitt des Katalysatorgehäuses her. Durch die Steigung des Kegelstumpfes läßt sich das Strömungsprofil über den Querschnitt des katalytischen Formkörpers beeinflussen. Dabei können die konusförmigen Abschnitte am anströmseitigen bzw. am abströmseitigen Ende des Katalysatorgehäuses unterschiedliche Steigungen aufweisen.A further improvement of the flow profile over the cross section of the catalytic Shaped body can be achieved if a housing for receiving the catalytic Shaped body is provided, with a tubular portion at its ends cone-shaped sections are formed. The truncated cone-like sections represent the Transition between the coming of the engine exhaust pipe, which a small Diameter, to the tubular portion of the catalyst housing ago. By the slope of the truncated cone can be the flow profile over the cross section of the influence catalytic shaped body. The cone-shaped sections on the on the upstream side or at the downstream end of the catalyst housing different Have slopes.

Der erfindunsgemäße katalytische Formkörper eignet sich besonders zur Reinigung von Stoffströmen, insbesondere Abgasströmen von Verbrennungsmotoren. The erfindunsgemäße catalytic molded body is particularly suitable for the purification of Material flows, in particular exhaust gas streams of internal combustion engines.

Der erfindungsgemäße katalytische Formkörper wird im weiteren unter Bezugnahme auf eine Zeichnung genauer erläutert. Gleiche Bezugszeichen in den Figuren bezeichnen dabei gleiche Gegenstände. Es zeigt:

Fig. 1
einen Längsschnitt durch einen erfindungsgemäßen katalytischen Formkörper, der in ein Katalysatorgehäuse eingebaut ist;
Fig. 2a - e
einen Längsschnitt durch verschiedene katalytische Formkörper, die jeweils in ein Katalysatorgehäuse eingebaut sind;
Fig. 3
ein Diagramm, in dem die Gasgeschwindigkeit im Katalysator gegen den radialen Abstand von der Achse des katalytischen Formkörper für die in den Figuren 2 a - e gezeigten Formen aufgetragen ist;
Fig. 4
einen Längsschnitt durch verschiedene gebräuchliche Formen für das Katalysatorgehäuse.
The catalytic molded body according to the invention will be explained in more detail with reference to a drawing. The same reference numerals in the figures indicate the same objects. It shows:
Fig. 1
a longitudinal section through a catalytic shaped body according to the invention, which is installed in a catalyst housing;
Fig. 2a - e
a longitudinal section through various catalytic moldings, each mounted in a catalyst housing;
Fig. 3
a diagram in which the gas velocity in the catalyst is plotted against the radial distance from the axis of the catalytic molded body for the shapes shown in Figures 2 a - e;
Fig. 4
a longitudinal section through various common forms for the catalyst housing.

Figur 1 zeigt einen Längsschnitt durch einen erfindungsgemäßen katalytischen Formkörper 1. Der katalytische Formkörper 1 wird von Abgas in Richtung des Pfeiles 2 durchströmt. Er weist eine anströmseitige Fläche 3, eine abströmseitige Fläche 4 sowie eine Umfangsfläche 5 auf. Der katalytische Formkörper kann von (nicht eingezeichneten) Kanälen durchzogen sein, die in Richtung der Längsachse 6 des Formkörpers 1 verlaufen. Die anströmseitige Fläche 3 des katalytischen Formkörpers 1 ist gekrümmt ausgestaltet, wobei die Linie, welche im Längsschnitt zwischen der Achse 6 des Formkörpers und der Umfangsfläche 5 verläuft, eine konkave Krümmung aufweist. Der katalytische Formkörper 1 bildet daher zur Anströmseite hin einen Kegel 7 aus, dessen Mantelfläche 8 eine konkave Krümmung aufweist. In der gezeigten Ausführungsform läuft der Kegel 7 in eine Spitze 9 aus. Diese ist beim Betrieb des Katalysators hohen mechanischen Belastungen ausgesetzt. Es ist daher auch möglich, den Kegel 7 als Kegelstumpf auszubilden oder die Spitze 9 abzurunden, um eine erhöhte mechanische Stabilität zu erreichen. Diese Ausführungsform ist durch die gestrichelte Linie 15 dargestellt. Die abströmseitige Fläche 4 des katalytischen Formkörpers 1 ist bei der dargestellten Ausführungsform planar ausgestaltet. Der katalytische Formkörper kann aus einem keramischen Material hergestellt sein, oder auch als Metallkatalysator ausgeführt sein. FIG. 1 shows a longitudinal section through a catalytic molded body according to the invention 1. The catalytic molded body 1 is traversed by exhaust gas in the direction of arrow 2. It has an upstream surface 3, a downstream surface 4 and a Peripheral surface 5 on. The catalytic shaped body may be of (not shown) Channels to be traversed, which extend in the direction of the longitudinal axis 6 of the shaped body 1. The upstream surface 3 of the catalytic molded body 1 is curved, wherein the line which in longitudinal section between the axis 6 of the shaped body and the Circumferential surface 5 extends, having a concave curvature. The catalytic shaped body 1 therefore forms a cone 7 towards the inflow side, whose lateral surface 8 is a concave one Curvature has. In the embodiment shown, the cone 7 runs in a tip 9 out. This is exposed to high mechanical loads during operation of the catalyst. It is therefore also possible to form the cone 7 as a truncated cone or the tip of the 9th To round off, to achieve increased mechanical stability. This embodiment is shown by the dashed line 15. The downstream surface 4 of the catalytic molded body 1 is designed planar in the illustrated embodiment. The catalytic molded body may be made of a ceramic material, or also be designed as a metal catalyst.

Der katalytische Formkörper 1 ist in ein Gehäuse 10, das beispielsweise aus Edelstahl besteht, eingebaut. Das Gehäuse 10 umfaßt einen rohrförmigen Abschnitt 11, dessen Innendurchmesser dem maximalen Außendurchmesser des katalytischen Formkörpers 1 entspricht, so daß das anströmende Abgas zwangsweise den katalytischen Formkörper 1 durchströmen muß. An den beiden Enden des rohrförmigen Abschnitts 11 schließen sich jeweils konusförmige Abschnitte 12a, 12b an. Durch diese konusförmigen Abschnitte 12a, 12b erfolgt die Aufweitung bzw. Reduzierung des Durchmesser der zu- bzw. abführenden Abgasrohre 13a, 13b auf den Durchmesser des katalytischen Formkörpers 1. Die Steigung des konusförmigen Abschnittes ist in ihrem Betrag auf der Anströmseite größer gewählt als auf der Abströmseite. Der Einbau des katalytischen Formkörpers 1 in das Gehäuse 10 erfolgt in der Weise, das der Kegel 7 des katalytischen Formkörpers 1 in den konusförmigen Abschnitt 12a des Gehäuses 10 hineinragt.The catalytic molded body 1 is in a housing 10, for example made of stainless steel exists, installed. The housing 10 comprises a tubular portion 11, whose Inner diameter of the maximum outer diameter of the catalytic molded body. 1 corresponds, so that the inflowing exhaust gas forcibly the catalytic molded body. 1 must flow through. Close at the two ends of the tubular portion 11 each cone-shaped portions 12a, 12b. Through these conical sections 12a, 12b, the expansion or reduction of the diameter of the incoming and outgoing takes place Exhaust pipes 13a, 13b on the diameter of the catalytic molded body 1. The slope the cone-shaped portion is chosen to be larger in magnitude on the upstream side than on the downstream side. The installation of the catalytic molded body 1 in the housing 10th takes place in the manner that the cone 7 of the catalytic molded body 1 in the cone-shaped portion 12a of the housing 10 protrudes.

In Figur 2 sind Längsschnitte durch verschiedene katalytische Formkörper 1 dargestellt, die jeweils in ein Gehäuse 10 eingebaut sind. Der Einfachheit halber sind jeweils nur die oberen Hälften der Katalysatorvorrichtung dargestellt. Die Darstellung ist schematisch und entspricht im Maßstab nicht einer realen Ausführung.FIG. 2 shows longitudinal sections through different catalytic molded bodies 1, each incorporated in a housing 10. For the sake of simplicity, only the shown upper halves of the catalyst device. The illustration is schematic and does not correspond to a real version on a scale.

Die vier dargestellten katalytischen Formkörper weisen jeweils einen kreisförmigen Querschnitt auf. Sie unterscheiden sich durch die Ausgestaltung der anströmseitigen bzw. abströmseitigen Stirnfläche. Dabei entsprechen die katalytischen Formkörper der Darstellungen 2a bis c Ausführungsformen aus dem Stand der Technik. Figur 2d zeigt eine Ausführungsform des erfindungsgemäßen katalytischen Formkörper. Figur 2e zeigt eine spezielle Ausführungsform der Mantelfläche des erfindungsgemäßen katalytischen Formkörpers.The four illustrated catalytic bodies each have a circular shape Cross-section on. They differ by the design of the upstream or downstream face. The catalytic shaped bodies correspond to the Representations 2a to c embodiments of the prior art. Figure 2d shows a Embodiment of the catalytic molded body according to the invention. FIG. 2e shows a special embodiment of the lateral surface of the catalytic according to the invention Molding.

Figur 2 a zeigt einen katalytischen Formkörper, dessen Stirnflächen sowohl auf der Anströmseite wie auf der Abströmseite planar ausgeführt sind. Figur 2b zeigt einen katalytischen Formkörper, dessen anströmseitige Fläche kegelförmig ausgebildet ist, wobei die Mantelfläche des Kegels keine Krümmung aufweist. Die abströmseitige Stirnfläche ist planar ausgeführt. Figur 2c zeigt einen katalytischen Formkörper, bei dem sowohl die anströmseitige, wie auch die abströmseitige Fläche als Mantel eines Kegels ausgeführt ist. Auch hier weist die Mantelfläche keine Krümmung auf. Figur 2d entspricht einer Ausführungsform des erfindungsgemäßen katalytischen Formkörpers. Auf der Anströmseite ist die Stirnfläche als Mantelfläche eines Kegels ausgeführt, wobei die Mantelfläche eine konkave Krümmung in Richtung auf die Längsachse des katalytischen Formkörpers aufweist.FIG. 2 a shows a catalytic molded body whose end faces are located both on the On the inflow side are designed as planar on the downstream side. FIG. 2b shows a catalytic shaped body whose upstream surface is conical, wherein the lateral surface of the cone has no curvature. The downstream end surface is planar. Figure 2c shows a catalytic shaped body in which both the on the inflow side, as well as the downstream surface is designed as a jacket of a cone. Again, the lateral surface has no curvature. Figure 2d corresponds to one Embodiment of the catalytic molded body according to the invention. On the On the inflow side, the end face is designed as a lateral surface of a cone, wherein the Lateral surface has a concave curvature in the direction of the longitudinal axis of the catalytic Having molded body.

Zur Untersuchung des Strömungsprofils wurde jeweils in einem Gehäuse ein monolithischer Formkörper in Wabenform aus Kupfer-Spinell-Aktivmasse eingebaut. Die hergestellten Formkörper entsprachen in ihrem Längsschnitt den Darstellungen in den Figuren 2a bis d. Der maximale Durchmesser der Monolithen betrug jeweils 13,2 cm die Längsausdehnung betrug bei der Ausführungsform gemäß Figur 2a 15,2 cm. Bei den Ausführungsformen b bis d entsprach die Längsausdehnung im Abschnitt mit konstantem Durchmesser der Ausführungsform nach Figur 2a. Alle vier Monolithen a bis d wurden jeweils von der gleichen Anzahl von quadratischen Längskanälen gleicher Lateralabmessungen durchzogen (400 cpsi; 7,2 mil). Die Monolithen wurden jeweils in gleiche Gehäuse eingebaut und in einer Testapparatur vermessen. Dazu wurde der zu testende Monolith jeweils mit einem Gasstrom derart beaufschlagt, das sich eine Gasbelastung von 90 000 h-1 ergab. Als Prüfgas wurde Atmosphärenluft verwendet. Die Temperatur des Gasstromes betrug 450°C, was einem für Abgastemperaturen charakteristischen Wert entspricht. Die Strömungsgeschwindigkeiten wurden jeweils auf der Abströmseite gemessen.To investigate the flow profile, a monolithic honeycomb shaped body made of copper-spinel active material was installed in each case in a housing. The moldings produced correspond in their longitudinal section to the illustrations in FIGS. 2a to d. The maximum diameter of the monoliths was 13.2 cm in each case, the longitudinal extent was 15.2 cm in the embodiment according to FIG. 2a. In embodiments b to d, the longitudinal extent in the constant diameter section of the embodiment of Figure 2a. Each of the four monoliths a to d were crossed by the same number of square longitudinal channels of equal lateral dimensions (400 cpsi, 7.2 mils). The monoliths were each installed in the same housing and measured in a test apparatus. For this purpose, the monolith to be tested was in each case subjected to a gas flow in such a way that resulted in a gas load of 90 000 h -1 . Atmospheric air was used as the test gas. The temperature of the gas stream was 450 ° C, which corresponds to a value characteristic of exhaust gas temperatures. The flow rates were measured on the downstream side.

Die Meßergebnisse sind in Figur 3 dargestellt. Dabei ist die normierte Lehrrohrgeschwindigkeit (y) gegen den Radius (x) aufgezeichnet. Die Normierung der Lehrrohrgeschwindigkeit wurde dabei in der folgenden Weise vorgenommen:
u(r) / u = normierte Leerrohrgeschwindigkeit
wobei

Figure 00090001
R = MonolithradiusThe measurement results are shown in FIG. The normalized teaching tube velocity (y) is recorded against the radius (x). The standardization of the teaching tube velocity was carried out in the following way:
u (r) / u = normalized empty pipe speed
in which
Figure 00090001
R = monolith radius

Die Kurven zeigen deutlich die im Vergleich zu den aus dem Stand der Technik bekannten Formen (a bis c) wesentlich homogenere Verteilung der Strömungsgeschwindigkeit in radialer Richtung im Fall des erfindungsgemäßen katalytischen Formkörpers (d).The curves clearly show that compared to those known from the prior art Forms (a to c) much more homogeneous distribution of flow velocity in radial direction in the case of the inventive catalytic shaped body (d).

Figur 2e zeigt schematisch eine Ausgestaltung der anströmseitigen Stirnfläche, wie sie z.B. bei gewickelten Katalysatoren auftritt. Durch die einzelnen Wicklungen werden an der anströmseitigen Stirnfläche jeweils Stufen 16 ausgebildet. Die Stufen 16 sind dabei so ausgeformt, daß die Umhüllende, die im Längsschnitt durch die gestrichelte Linie 17 dargestellt ist, eine konkave Krümmung aufweist.Figure 2e shows schematically an embodiment of the upstream face, as e.g. occurs in wound catalysts. By the individual windings are at the each upstream step 16 formed steps. The steps 16 are like this formed that the envelope, in longitudinal section through the dashed line 17th is shown having a concave curvature.

Figur 4 zeigt schematisch Querschnitte durch verschiedene Gehäuseformen für katalytische Formkörper. In den Fällen a, b, d fällt dabei die Längsachse 14 des zuführenden Abgasrohres mit der Längsachse 6 des katalytischen Formkörpers zusammen. In diesen Fällen wird erfindungsgemäß die anströmseitige Fläche als Mantelfläche eines symmetrischen Kegel bzw. Kegelstumpfes ausgeführt. Im Fall c fällt die Längsachse 14 des zuführenden Abgasrohres nicht mit der Längsachse 6 des katalytischen Formkörpers zusammen. In diesem Fall ist die anströmseitige Fläche als Mantelfläche eines unsymmetrischen Kegels bzw. Kegelstumpfes gemäß der erfindungsgemäßen Lehre auszuführen.Figure 4 shows schematically cross sections through different housing shapes for catalytic shaped bodies. In the cases a, b, d thereby falls the longitudinal axis 14 of the feeding exhaust pipe with the longitudinal axis 6 of the catalytic molded body together. In these cases, the inflow-side surface according to the invention as a lateral surface of a executed symmetrical cone or truncated cone. In case c, the longitudinal axis 14 drops the feeding exhaust pipe not with the longitudinal axis 6 of the catalytic shaped body together. In this case, the inflow-side surface is as a lateral surface of a unbalanced cone or truncated cone according to the teaching of the invention perform.

Claims (12)

  1. A shaped catalytic structure having an upstream surface (3), a downstream surface (4) and a circumferential surface (5), wherein said upstream surface (3) is configured as a lateral surface (8) of a conical or frustoconical projection (7), said lateral surface (8) having at least sections with a concave curvature.
  2. A shaped catalytic structure as claimed in claim 1, wherein said lateral surface (8) has sections with a convex curvature.
  3. A shaped catalytic structure as claimed in claim 1 or 2, wherein said upstream surface (3) has a smooth curvature.
  4. A shaped catalytic structure as claimed in any of claims 1 to 3, wherein said downstream surface (4) is planar.
  5. A shaped catalytic structure as claimed in any of claims 1 to 3, wherein said downstream surface (4) is curved.
  6. A shaped catalytic structure as claimed in any of claims 1 to 5, constructed as a monolith.
  7. A shaped catalytic structure as claimed in any of claims 1 to 6, constructed of a multiplicity of superposed layers of a structured sheetlike material.
  8. A shaped catalytic structure as claimed in any of claims 1 to 7, constructed of a catalytically active material.
  9. A shaped catalytic structure as claimed in any of claims 1 to 8, pervaded by channels which extend parallel to the longitudinal axis (6) and whose walls are preferably coated with a catalytically active material.
  10. A shaped catalytic structure as claimed in any of claims 1 to 9, accommodated in a housing (10) having a tubular section (11) ending in nappe-shaped sections (12a, b).
  11. A shaped catalytic structure as claimed in claim 10, wherein said lateral surface (8) of said conical or frustoconical projection (7) is disposed at least partially within one of said nappe-shaped sections (12a, b) of said housing (10).
  12. The use of a shaped catalytic structure as claimed in any of claims 1 to 11 for purifying streams of material, especially exhaust gas streams from internal combustion engines.
EP00121383A 1999-10-14 2000-10-12 Hydrodynamically optimized catalytic body Expired - Lifetime EP1092846B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19949568 1999-10-14
DE19949568A DE19949568A1 (en) 1999-10-14 1999-10-14 Hydrodynamically optimized catalytic molded body

Publications (3)

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EP1092846A2 EP1092846A2 (en) 2001-04-18
EP1092846A3 EP1092846A3 (en) 2003-06-25
EP1092846B1 true EP1092846B1 (en) 2005-04-06

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JP (1) JP2001162178A (en)
AT (1) ATE292745T1 (en)
DE (2) DE19949568A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10021166A1 (en) * 2000-04-29 2001-11-08 Univ Stuttgart Catalyst matrix used for purifying IC engine exhaust gases has a longitudinal axis running in the main flow direction of the exhaust gases, a bent inlet surface, and an outlet surface
US20020076365A1 (en) * 2000-12-14 2002-06-20 Detroit Diesel Corporation Emission control catalyst assembly for an engine of a motor vehicle
FR2876145A1 (en) * 2004-10-05 2006-04-07 Renault Sas Exhaust gas pollution control device for internal combustion engine of motor vehicle, has porous monolith on which gas, discharged by engine, arrives, and having inlet side equipped with protrusion presenting hemi-spherical dome shape
DE102005042057A1 (en) * 2005-09-05 2007-03-08 Robert Bosch Gmbh Filter element with improved soot distribution

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2201881A1 (en) 1972-01-15 1973-07-19 Volkswagenwerk Ag Porous block exhaust gas catalyst - tapered at its end(s) to improve gas flow profile through the block
US3910850A (en) * 1973-12-19 1975-10-07 Grace W R & Co Contoured monolithic substrate
DE2364425A1 (en) * 1973-12-22 1975-07-10 Boysen Friedrich Kg Catalyst chamber construction - for a monolithic catalyst used in after-burning of unburnt constituents in exhaust gases
DE2428964A1 (en) 1974-06-15 1976-01-02 Bosch Gmbh Robert Reactor insert for exhaust gas detoxification - with conically tapering inlet end
US3964875A (en) 1974-12-09 1976-06-22 Corning Glass Works Swirl exhaust gas flow distribution for catalytic conversion
JPS62152014U (en) 1986-03-18 1987-09-26
JP2664118B2 (en) 1992-11-20 1997-10-15 日本碍子株式会社 Curved honeycomb structure
EP0818613A1 (en) 1996-07-08 1998-01-14 Corning Incorporated Exhaust gas purifying system
DE19749379A1 (en) 1997-11-07 1999-05-20 Emitec Emissionstechnologie Catalyst carrier body with improved heat radiation

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DE19949568A1 (en) 2001-04-19
JP2001162178A (en) 2001-06-19
ATE292745T1 (en) 2005-04-15
DE50009972D1 (en) 2005-05-12
EP1092846A3 (en) 2003-06-25
EP1092846A2 (en) 2001-04-18

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