DE4234931A1 - Catalytic converter for automotive and other fossil fuel applications - has roughened gas passage surfaces to disrupt laminar gas flow and maximising gas contact with catalytic material - Google Patents

Abstract

Catalytic converter has a number of heat- and corrosion-resistant walls forming gas flow passages (3) with inlets (4) and outlets (5), the surfaces of which have a coating of catalytic material. The novelty is that the surfaces bearing catalytic material also have deposits (6) of fibrous, grainy or powdery material to leave a rough finish. USE/ADVANTAGE - The assembly is a catalytic converter for automotive use, or for use in association with the combustion of fossil fuels. The rough surface improves the contact of the gases with the catalyst by disrupting laminar gas flow.

Description

The invention relates to a catalyst for Beseiti generation of harmful components from the exhaust gas Internal combustion engine or from an incinerator for fossil fuels, the one or more tempera door-resistant and corrosion-resistant catalytic converter walls has, the flow channels form, the upper surfaces of the catalytic converter walls on which the exhaust gas along the path from an inlet to an outlet flows, provided with catalytically active materials are.

Known catalysts have the disadvantage that the Surfaces of the catalyst walls very smooth or clean are low in exercise so that the gas is laminar through the channels  of the catalyst flows. Through this laminar flow only a small part of the exhaust gas comes with the kata lytic coating of the catalyst walls in Berlin tion. For this reason, the efficiency of the kata lysators limited.

To avoid this disadvantage is already pre been hit by skis inserted into the channels kanen, obstacles or the like or by a Twisting and / or moving the channels a turbulent to achieve the flow of exhaust gas through which due to the turbulence better contact with the Catalyst walls occurs.

A disadvantage of the known method, however, is that either still unsatisfied with the result is lend, or that a relatively high effort is necessary to achieve a good effect.

The present invention therefore has the object reasons, a catalyst of the type mentioned to improve so that with little effort sem high efficiency can be achieved, esp special in which an improved exhaust system is achieved becomes.  

According to the invention this object is achieved in that at least part of the surfaces of the catalyst walls by fibrous, granular or powdery materials is roughened.

Due to the roughening of the surfaces according to the invention the catalyst walls will not only become a vortex of the exhaust gas flowing through and thus a better one Contact with the catalytic coating of the Catalyst walls are reached, but beyond that thus also enlarging the surface of what is happening if it has a positive effect on efficiency. The con Degree of verticalization of the harmful substances present in the exhaust gas Components are significantly improved.

In order to achieve optimal effects, it can be pre-designed hen be that the applied materials also have catalytic properties. If necessary can even apply the materials to be applied at all form the catalytic coating and as the basis for the catalyst body will only be a base material facher and cheaper type used, only It is important to ensure that it is sufficiently temperature-resistant and is corrosion resistant.

It is advantageous if it is provided that the  materials to be applied have different thicknesses and / or have sizes.

By different thicknesses and / or sizes achieve even better swirling.

The catalyst body can both with regard to its Form as well as its structure according to the requirements changes.

A very advantageous embodiment results when it is provided that the catalyst from a tape ge is that with nub or honeycomb-like elevation gene or is provided with wave-like bulges, and which is wound in a cylindrical shape, on one Face the inlet and on the other face the outlet is arranged.

In principle, such a structure is already in place of technology, the relatively thin band consisting of one high temperature resistant and corrosion resistant plant fabric, generally sheet steel, is formed that is coated with catalytically active substances. For this, e.g. B. a known wash-coat Ver driving can be used. The metal strip is in a suspension or a ceramic slurry in which kataly  table materials such. B. platinum, palladium or Rhodium is introduced, immersed. Subsequently becomes the sheet metal strip provided with a coating layer dried in a sintering oven and "burned" or sintered on.

It has now emerged as a disadvantage that the catalytic coating at very high temperatures temperatures that can occur during use and / or can peel off after a long period.

Surprisingly, it has now been found that then when it is provided that the materials before immersing the metal strip in a with kataly Coating bath provided with table-like substances are applied, the ka taking place in the immersion bath talytical coating much better on the Ka Talysator body or the sheet metal strip adheres. This means tet that on the surfaces of the catalyst walls applied material a second unexpected Brings advantage.

Another advantage of the application according to the invention of the materials on the catalyst walls in that possibly on a separate coating of the catalyst body with catalytic Be  components can be dispensed with if the open bringing materials themselves accordingly catalyti own effects and in a corresponding Layer thickness can be applied.

The application of materials to the catalyst walls can e.g. B. by sintering or by a flame inject. In the latter method are the desired materials in powder form introduced a flame beam from a welding torch and liquefied accordingly on the catalyst walls sprayed.

Of course, within the scope of the invention other application methods possible.

As the base material for the catalyst body in tape Steel sheet has proven to be very suitable put that with 2 to 5 weight percent aluminum and up to 24% by weight of chromium, preferably 22 to 24 percent by weight is alloyed.

The following is an embodiment of the invention shown in principle on the basis of the drawing.

It shows:  

Fig. 1 is a perspective view of a Kata analyzer, the form is wound from a tape in a Zylin;

Fig. 2 a section of a enlarged view of one end of the catalyst of FIG. 1.

A catalyst is formed from a sheet metal strip 1 , which has a thickness between 0.03 and 0.5 mm, preferably 0.05 to 0.1 mm, and which is seen on one side with a surface with undulating bulges, which through a plurality of shafts 2 arranged one behind the other is formed. The waves 2 he stretch across the entire width of the metal strip 1 . To form a catalyst, the accordingly elastic sheet metal strip is wound spirally, whereby a plurality of flow channels 3 are ben, which are each limited by the sheet metal strip 1 and the shafts 2 . The inlet for the gas to be cleaned takes place on one end face 4 while the outlet is on the other end face 5 . As he can see, the exhaust gas flows along the catalyst walls that are created in this way and that are provided with catalytically active materials or components.

Before winding the sheet metal strip 1 and thus before finishing the catalyst, the sheet metal strip 1 is hen on all sides, ie thus also the shafts 2 , with fibers, granular or powdery materials 6 verses. The materials 6 can e.g. B. are sintered onto the belt 1 and the shafts 2 and in this way result in a rough surface, as a result of which the incoming exhaust gas swirls accordingly and leads to increased contacting of the catalyst walls.

The catalytic effect of the catalyst walls can be achieved by using materials 6 which have catalytic properties and which are applied to the sheet metal strip 1 in a corresponding thickness.

The materials 6 are applied in different thicknesses or sizes, whereby they can extend over a range from a few μ to about 1 mm. The heights of the shafts 2 depend on the application, in particular the size of the combustion engine and can be between 0.5 and 20 mm.

Alternatively, the catalytic effect of the catalyst walls can be followed by a wash coat coating, in which case the material for roughening the surfaces is previously brought up onto the metal strip 1 .

Of course, the shape of the catalyst and its formation from a strip material is only mentioned as an example. The same applies to the waveform. If necessary, other configurations are of course possible and instead of waves, rectangular or triangular ribs, nubs, webs or other configurations are also possible, which stood from the individual layers of the sheet metal strip to be wound to form flow channels 3 .

Instead of a flat sheet metal strip with arranged on it Of course, waves can also be used as band material a sheet metal strip is used that is purely in wave form is wrapped.

The wound sheet metal strip can be used for stabilization closing at least partially on the front sides be soldered or welded. same for of course for the end seam that runs along a Surface line runs.

Claims (11)

1. Catalyst for the removal of harmful components from the exhaust gas of a combustion engine or from a fossil fuel incineration plant which has one or more temperature-resistant and corrosion-resistant catalyst walls which form the flow channels, the upper surfaces of the catalyst walls on which the exhaust gas is present ent the flow from an inlet to an outlet ent, are provided with catalytically active materials, characterized in that at least part of the surfaces of the cata- tor walls are roughened by fibrous, granular or powdery materials ( 6 ) applied thereon. 2. Catalyst according to claim 1, characterized in that the materials applied ( 6 ) have catalytic properties. 3. Catalyst according to claim 1 or 2, characterized in that the materials ( 6 ) have different thicknesses and / or sizes. 4. Catalyst according to one of claims 1 to 3, characterized in that the catalyst is formed from a strip ( 1 ) which is hen with nubs or honeycomb increases or with wave-like bulges (waves 2) verses, and which is wound in a cylindrical shape is, the inlet ( 4 ) being arranged on one end face and the outlet ( 5 ) being arranged on the other end face. 5. Catalyst according to one of claims 1 to 4, characterized in that the materials ( 6 ) are sintered onto the catalyst walls. 6. Catalyst according to one of claims 1 to 5, characterized in that the materials ( 6 ) are applied to the sheet metal strip ( 1 ) before coating a sheet metal strip with catalytically active substances. 7. Catalyst according to claim 6, characterized in that the materials ( 6 ) are applied before immersion of the sheet metal strip ( 1 ) in a coating bath provided with catalytically active substances. 8. Catalyst according to one of claims 1 to 4, characterized in that the materials ( 6 ) are applied to the catalyst walls by flame spraying. 9. Catalyst according to one of claims 4 to 8, characterized in that the strip ( 1 ) is formed from a steel sheet which is alloyed with 2 to 5 weight percent aluminum and with a chromium content of up to 24 weight percent. 10. Catalyst according to one of claims 4 to 9, characterized in that the wall thickness of the sheet metal strip ( 1 ) is between 0.03 and 0.5 mm, preferably 0.05 to 0.1 mm. 11. Catalyst according to one of claims 1 to 10, characterized in that the thicknesses or diameters of the materials applied to the catalyst walls ( 6 ) are up to 1 mm.