EP0151229A1 - Matrix for catalytic reactor - Google Patents

Abstract

A matrix for a catalytic reactor for exhaust gas purification in internal combustion engines is described, which is constructed from corrugated steel strips which can be coated with catalyst material and which are arranged in several layers adjacent to one another in a tubular housing through which the exhaust gas flows. The individual layers are parts of a coherent strip-shaped sheet steel strip which is folded in a meandering manner, in particular in a zigzag shape. This configuration enables simple manufacture and can lead to an arrangement in which gas equalization is also possible in the radial direction, which can lead to a more uniform flow profile and better utilization of the reaction of the matrix.

Description

The invention relates to a matrix for a catalytic reactor for exhaust gas purification, preferably in internal combustion engines and power plants, which are constructed from corrugated sheet steel strips coated with catalyst material, which lie adjacent to one another in several layers in a tubular housing o through which the exhaust gas flows axially and parallel to the boundary surfaces of the layers. the like are arranged.

A matrix of this type is known (DE-PS 27 33 64o), in which steel strips constructed either from three layers, namely from two smooth strips and a corrugated strip enclosed between them, or from only one type of corrugated steel strip, are used as sheet steel strips , which are wound into a matrix and are designed such that tab-shaped punched-out punchings of one layer each press into corresponding openings in the adjacent layer, so that the wound-up layers of the steel sheet strips are secured in the axial direction. It is also known (DE-OS 29 02 779), in order to increase the turbulence of the flow through such a matrix, either to apply strips of corrugated sheets to smooth steel sheet strips or to connect individual smooth strips with a corrugated sheet. All known designs, however, have the disadvantage, on the one hand, that the production of such a matrix is relatively complex, in particular if the steel sheet strips used in turn already consist of several strips. The main disadvantage, however, is that the known types of a matrix can only be used in approximately circular tubular housings because of the winding process, and that the design of the outer shape of such reactors is limited by the structure of the matrix. Another disadvantage is that a radial compensation of the matrix and Exhaust gases flowing through the reactor are not possible or only very incompletely, even if steel strips of the type mentioned above are provided with openings.

The invention is therefore based on the object of designing a matrix of the type mentioned at the outset in such a way that reactors with largely any desired external shapes can be created without great construction expenditure, which also offer the possibility of better radial compensation of the flow profile of the exhaust gas.

Starting from a matrix of the type mentioned at the outset, the invention consists in the fact that the individual layers are parts of a single strip-shaped sheet steel strip which is folded in a meandering shape. This configuration allows the individual layers of the sheet steel strip to be joined onto one another in a relatively simple manner, and the manufacturing process already leaves them open at least on one side, so that, in contrast to a wound matrix, where gas equalization occurs even when the strip-shaped arrangement of corrugated strips is in itself In some respects permeable bands, gas compensation is only possible in the circumferential direction, and there is now a far simpler possibility for a radial passage of the exhaust gas, which leads to an equalization of the flow profile. As a result, the radially outer layers of the catalyst material can also participate in the reaction process. The matrix can be better used.

A very simple embodiment of the matrix according to the invention results if the individual layers are folded onto one another in a zigzag shape. If the layers in the direction of folding are un have the same length, oval or round matrix inserts can be realized without a complicated construction from several parts being necessary. If the layers have the same length in the direction of folding, rectangular or Roman reactors can be constructed so that, depending on the space available, for example, in a motor vehicle, the shape of the matrix for the catalytic reactor for exhaust gas purification can be adapted to this space .

In order to simplify the manufacturing process, it can be provided that the steel strips used to form the matrix are provided at the stops with prefabricated kink locations, for example in the manner of perforations, so that the manufacture of a matrix according to the invention, the individual layers of which, for example, zigzag-shaped are folded onto one another, can be achieved in a simple manner in that a single band, for example in the same way as continuous paper, folds behind a printer when it falls vertically into a shaft, is also passed into a shaft, at the folds easily bends and thereby folds onto each other to the desired matrix shape. The matrix formed in this way can then be inserted, for example, into a two-part housing and pressed together by this and also fastened to one another in the axial direction. But it can also be inserted axially through a funnel into a closed tubular housing.

The sheet steel strip used for the production of the matrix can be constructed in a manner known per se from three layers, of which the two outer strips are each smooth strips with or without openings and the middle one is a corrugated strip, which is also formed with or without openings or interruptions can be. But it is easier if the sheet steel strip is a single corrugated strip, the corrugations of which, in a known manner, have a triangular cross section, each with straight walls on the outside, which are interrupted by gaps running transversely to the strip direction, but whose width in the strip direction is smaller than . is the width of the outer walls. Such a corrugated tape has the advantage that the individual layers that are folded onto one another do not slide into one another in this superimposed state, so that they can be folded up without the use of smooth strips. These corrugated strips can be provided with openings so that the radial compensation is not only possible in the direction of the layers folded onto one another, but can also take place transversely thereto. The free passage cross section of all openings is expediently chosen so that a proportion of at least 5% of the boundary surfaces adjacent to one another in the individual layers is achieved. The perforations must be coordinated in such a way that a good radial compensation is achieved without the loss of active surface having a negative effect. The perforations must also be distributed uniformly over the surface of the boundary surfaces, so that the aforementioned effect of a good radial compensation of the exhaust gas flow is achieved with an equalization of the flow profile.

• Fig. 1 eine Möglichkeit einer erfindungsgemäßen Faltung eines für die Herstellung der Matrix verwendeten Stahlblechbandes in Mäanderform,
• Fig. 2 die schematische Darstellung ein in einem zick-zack-förmigen Mäander auf-einandergefalteten Stahlblechbandes zur Bildung eines ovalen Reaktoraußenkörpers,
• Fig. 3 die zick-zack-förmige Aufeinanderfaltung eines Stahlblechbandes zur Bildung eines runden Reaktorkörpers,
• Fig. 4 die zick-zack-förmige Aufeinanderfaltung eines Stahlblechbandes zur Bildung eines rechteckigen Reaktorkörpers,
• Fig. 5 eine perspektivische Skizze eines Reaktors, der durch das Aufeinanderfalten eines aus drei Lagen bestehenden, für die Bildung der Matrix verwendeten Stahlblechbandes hergestellt ist,
• Fig. 6 eine perspektivische Teilansicht des für die Herstellung der Matrix der Fig. 5 verwendeten Stahlblechbandes,
• Fig. 7 die perspektivische Teildarstellung eines mit dreieckförmigen Wellungen versehenen Stahlblechbandes, das in besonders einfacher Weise zur Bildung einer erfindungsgemäßen Matrix verwendet werden kann und
• Fig. 8 die schematische Darstellung einer für einen rohrförmigen Außenkörper geeigneten Matrix, die aus einem Wellband gemäß Fig. 7 hergestellt ist,

The invention is outlined in the drawing using exemplary embodiments and is explained in the following. Show it:

• 1 shows a possibility of folding according to the invention of a sheet steel strip used in the manufacture of the matrix in a meandering shape,
• 2 shows the schematic representation of a sheet steel strip folded on top of one another in a zigzag-shaped meander to form an oval outer body of the reactor,
• 3 the zigzag-shaped unfolding of a sheet steel strip to form a round reactor body,
• 4 shows the zigzag-shaped unfolding of a sheet steel strip to form a rectangular reactor body,
• 5 shows a perspective sketch of a reactor which is produced by unfolding a three-layer steel sheet strip used for forming the matrix,
• 6 is a partial perspective view of the sheet steel strip used for the production of the matrix of FIG. 5,
• Fig. 7 is a partial perspective view of a sheet steel strip provided with triangular corrugations, which can be used in a particularly simple manner to form a matrix according to the invention and
• 8 shows the schematic representation of a matrix suitable for a tubular outer body, which is produced from a corrugated strip according to FIG. 7,

1 to 4 show possibilities of how sheet steel strips according to the invention can be folded into a matrix for a catalytic reactor for exhaust gas purification. For example, a strip of the type shown in FIG. 6 or in FIG. 7 can be used as the steel strip, which, as in FIG. 6, is composed of two smooth steel strips 1 with openings 2 and an intermediate corrugated strip 3 which 7 are soldered to one another, for example, or consist of a single corrugated strip - as shown in FIG. 7 - whose corrugations have a triangular cross section and which are arranged such that the outwardly facing surfaces 4 of each corrugation are wider in the direction of arrow 5, than the gap 6 located between these surfaces. Such a band cannot slide together when it is folded up with its individual layers. Of course, it is also possible to use other forms of tapes, but care must be taken to prevent the individual tapes from slipping into one another.

Tapes of this type can now be folded according to the invention in a meandering shape in the manner shown in FIG. 1 as a single continuous tape 7, so that a matrix according to FIG. 1 with a rectangular outer cross section is formed, which can be inserted into a rectangular housing 8. It is simpler to provide a zigzag meander as shown in FIG. 2, 3 or 4 for the folding, whereby in each case prefabricated folding points, for example in the manner of a perforation, can be provided at the folding points 9, which lead to the fact that the continuous ribbon 7 ', the zig-zag folded, successive sets itself automatically to the individual layers 7a, 7b, when it is, for example, lowered from above into a corresponding well and successive folds ierqtreifen there like a Pa ^p. It is possible, as indicated in FIGS. 2 and 3, to provide the individual layers 7a, 7b with a different fold length a or b, so that oval outer dimensions for insertion into an oval tubular housing 10 - as in FIG. 2 - or in a round tubular housing 11 - as in Fig. 3 - can be achieved by the folding process. Of course, it is also possible to form the individual layers with the same folding length b as in FIG. 4, so that the matrix formed in this way can be inserted into a rectangular outer housing 12 similar to that in FIG. 1.

In a practical embodiment, this can be done, for example, as indicated with reference to FIG. 5, in that a Sheet steel strip of the type shown in Fig. 6 is folded up in the manner shown in Fig. 2 and then. is jammed between the upper part 13 and the lower part 14 and is thereby also held in the axial direction, ie in the direction of the flow, which is indicated by the arrow 15. A matrix formed in this way, in which, of course, the individual sheets 1 and 3 provided for production are coated with catalyst material in a known manner, has the advantage that it is very easy to produce. Due to the arrangement of the openings 2, gas equalization is also possible perpendicular to the boundary surfaces 17 of the individual layers 7A, 7B. The clear overall cross section of all openings 2 can be chosen so that this radial compensation is achieved to form a uniform flow profile. It has been shown that this is generally the case if the total cross section of the openings 2 makes up more than 5% of the area of the boundary surfaces 17. The openings can be provided in the corrugation direction or transversely thereto (2 '), which is more advantageous since they overlap better when layering.

FIG. 8 shows the possibility of a practical embodiment of a matrix for a round tubular housing 11, which is produced from a sheet according to FIG. 7; in this case the tube 11 is in one piece. The folded matrix according to FIG. 3 can be pushed into the tubular housing 11 in the direction of the arrow 18 by a funnel indicated by a broken line. The clamping forces can be chosen so that an axial fit of the entire matrix is achieved; additional axial fastenings are of course also possible, in particular the matrix can be soldered or welded.

Claims (10)

1. Matrix for a catalytic reactor for exhaust gas purification, preferably in internal combustion engines, which is constructed from corrugated sheet steel strips which can be coated with catalyst material and which lie adjacent to one another in several layers in a tubular housing or the like through which the exhaust gas flows axially and parallel to the boundary surfaces of the layers. are arranged, characterized in that the individual layers (7A, 7B, 7C ...) are parts of a coherent strip-shaped sheet steel strip (7, 7 ') which is folded over one another in a meandering shape. 2. Matrix according to claim 1, characterized in that the individual layers (7A, 7B) are folded onto one another in a zigzag shape. 3. Matrix according to claims 1 and 2, characterized in that the layers (7a, 7b) have an unequal length (a, b) in the direction of folding. 4. Matrix according to one of claims 1 to 3, characterized in that the steel strips (7, 7 ') are provided at the folds with prefabricated kinks (9). 5. Matrix according to claim 4, characterized in that the kinks (9) are designed as perforations. 6. Matrix according to one of claims 1 to 5, characterized in that the sheet steel strip (7, 7 ') is constructed from three layers (1 or 3), of which the two outer smooth strips (1) with or without openings ( 2) and the middle (3) is a corrugated band, which is also formed with or without openings or interruptions. 7. Matrix according to one of claims 1 to 5, characterized in that the sheet steel strip (7, 7 ') is a single corrugated strip, the corrugations of which have a triangular cross-section, each with straight walls (4) lying on the outer sides, which extend transversely to the strip direction running column (6) are interrupted, the width in the band direction (5) is smaller than the width of the outer walls (4). 8. A matrix according to claim 7, characterized in that the walls (4) lying on the outside in each case are interrupted by gaps (2 ') running in the band direction, which cover at least two corrugations. 9. Matrix according to claim 7, characterized in that the corrugated strips are provided with openings (2). 10. Matrix according to claim 8, characterized in that the free passage cross section of all openings (2) has a share of more than 5% of the adjacent surfaces (17) in the individual layers (7a, 7b).

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