Siemens Aktiengesellschaft

Klaus Huttenhofer

Peter Heinz Fischer

Erich Hums

Ronald Neufert

Horst Spielmann

Lothar Balling

Wolfgang Herr

Josef Sprehe

Gunther Spitznagel

Hendrik Lammers

Heimo Friede

Josef-Konrad Beer

An SCR catalyst containing titanium, molybdenum and vanadium has the particular characteristic that its catalytic activity is significantly less than that of a tungsten-containing catalyst. That disadvantage has been compensated for in the past by using a comparatively large volume of catalyst. In contrast to the conventional practice of using a molybdenum oxide proportion of about 10 to 12% by weight, the invention proposes that the molybdenum proportion of the catalyst, in the form of molybdenum trioxide MoO.sub.3, is about 0.01 to 5% by weight, preferably 1.5 to 4% by weight, relative to the weight of the catalyst mass. A catalyst containing this amount of molybdenum thus has an activity comparable to that of a tungsten-containing catalyst. The invention is applicable to all deNO.sub.x catalytic converters which call for the simultaneous presence of a reducing agent, in particular plate-type and honeycomb-type catalytic converters.

Catalyst for reducing the nitrogen oxide concentration in a flowing

A plate-type catalytic converter includes a holder device and plates being coated with a catalytically active composition, being held one above the other in the holder device and extending in a main flow direction. The plates include first and second adjacent plates forming at least one reaction chamber. At least the first plate has an approximately corrugated first structure oriented obliquely relative to the main flow direction for deflecting a flow medium flowing along the first structure from the main flow direction.

Plate-type catalytic converter

A flow duct conducts a gaseous second fluid medium in a given flow direction and has a given cross-sectional area and a given hydraulic diameter. A combined feed and mixing device for introducing a first fluid medium into the second fluid medium in the flow duct and for mixing the fluid media includes at least one tube conducting the first fluid medium and having from 0.05 to 10 feed orifices per m.sup.2 of the given cross-sectional area. A mixing insert disposed downstream of the at least one feed orifice in the given flow direction is spaced apart from the feed orifices by a distance of from 0.05 to 3 times the given hydraulic diameter. The mixing insert has mixing elements being small relative to the given hydraulic diameter and being disposed in mutually parallel rows in a plane oriented at an angle to the given flow direction. The mixing elements of each of the rows are inclined relative to a plane in the same direction to one another and in opposite direction to the mixing elements of each adjacent row.

Combined feed and mixing device

A regenerative preheater includes a heat accumulator and a catalyst through which a raw gas containing a harmful component can flow and through which a clean gas can flow in alternation. A first admission point for a gaseous reagent is disposed upstream of the catalyst in a flow path of the raw gas. A second admission point for the gaseous reagent is disposed upstream of the catalyst in a flow path of the clean gas. A method for operating a regenerative preheater includes passing a raw gas containing a harmful component and passing a clean gas through a heat accumulator and a catalyst in alternation. A a reagent for a catalytic reaction is introduced into both a flow path of the raw gas and a flow path of the clean gas.

Regenerative preheater and method for operating the same

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Heroldsberg, Germany

Klaus Huttenhofer