JPH03181336A - Catalytic element for use for liquid- or gas-like medium - Google Patents

Abstract

PURPOSE: To enhance catalyst efficiency by generating a turbulent flow by slantingly positioning catalyst plates of catalytic elements so as to form the flowing channels between the plates in diminishing or augmenting shape. CONSTITUTION: Numerous catalyst plates 8 and 10, which do not allow fluid medium 4 to pass through them, are positioned in parallel in the catalytic element 2 and the adjacent catalyst plates 8 and 10 are positioned slantingly to each other, thereby the clearances between the plates form the flow channels 12 and 14 for fluid medium 4 which are augmenting or diminishing when viewed in the flow direction. As a result, the medium is forcibly accelerated or deterred thus generating a turbulent flow, thereby the catalytic activity is enhanced and especially nitrogen oxides from exhaust gases, by ammonium gas, are catalytically removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a catalyst for a flowing liquid or gaseous medium having a number of medium-impermeable catalyst plates arranged in parallel and spaced apart from each other. In particular, it relates to a catalytic element for catalytically removing nitrogen oxides from exhaust gas using ammonia gas.

[Conventional technology]

The periodical “Chemie-Technik”
In the flue gas purification system known from J. vol. 15 (1986), no. denitrification oxide (DeNOx) with a catalyst
guided into the chimney through a device.

The DeNOx device advantageously operates according to the SCR principle using an ammonia (NHs) introduction nozzle.

A honeycomb type or plate type catalyst is placed in the DeNOx device. Plate catalysts consist of a bundle of shaped plates arranged parallel to each other.

Each of these bundles consists of a thin carrier plate made of high-grade steel expanded metal lath coated with catalytically active compound or catalytic material. These catalysts are advantageously used for the catalytic reduction of nitrogen oxides in flue gases from coal-fired power plants with NHs as reducing agent.

Siemens brochure “No, Reducti with Plate and Honeycomb Catalytic Converters”
on with Plate-Type and Ho
neycomb-TypeCatalytic Con
verters, 1 (Call number A19 100-U
311-A106-X-7600, April 1988) describes industrially produced plate-type and honeycomb-type catalysts for reducing nitrogen oxides. In this case, the ceramic or metal catalytic elements are collected in a mold and, if necessary, stacked. In the case of plate-type catalysts, the catalyst plates have continuous corrugations extending in the direction of flow, the corrugations acting as spacing elements for each adjacent catalyst and at the same time serving to form individual flow channels.

From the Federal Republic of Germany Patent No. 2853023,
Catalytic elements having a plate-like structure of the type mentioned at the outset are known. This element has a number of catalysts shaped like plates which are arranged parallel to the nitrogen oxide-containing flue gas stream. Each plate-shaped catalyst consists of a metal plate coated on both sides with a catalytically active material. This metal plate may be perforated, ie with stampings or windows, or consist of expanded metal lath.

A device with alternating corrugations on adjacent catalytic plates of a catalytic element is known from DE 37 06 086 A1.

Finally, the Federal Republic of Germany Patent Application Publication No. 2614692
The patent describes a catalyst body consisting of two catalyst plates arranged in a V-shape with respect to one another. But unlike the catalyst plate according to the invention, it has a flowing medium,
It is important in the present invention that the plates be impermeable, for example permeable to flue gases.

[Invention or problem to be solved]

The present invention provides that in a catalyst element having a plate-like structure and having mutually parallel catalyst plates and mutually partitioned flow channels, the fluidizing medium mainly forms a laminar flow and slides along the catalyst wall, and the internal surface and This is based on the observation that there is only insufficient contact. Furthermore, the invention is based on the consideration that the utilization of the catalyst can be improved if it is ensured that the fluidizing medium produces a certain turbulence inside the catalytic element. The idea is that a certain turbulence in order to improve the catalytic action in the catalyst plate of the catalyst shaped body of the type described can be obtained by varying the width of the flow channels.

The object of the invention is to design a catalytic element of the type mentioned at the outset in such a way that the catalytic action is enhanced by enhanced turbulence. At the same time, it is advantageous to have a spacer of simple construction.

[Means to solve the problem]

According to the invention, this problem is achieved in that two adjacent catalyst plates are arranged at an angle to one another, so that the flow channels for the medium between the two plates are formed in a tapering or diverging manner. resolved. In this case, by forcing the medium to accelerate or retard, the boundary layer with each catalyst plate is influenced.

A particularly advantageous embodiment is achieved by providing correspondingly contoured corrugations in the two catalyst plates in order to configure the flow channels between them in a tapering or diverging manner. These corrugations have the function of spacers and ensure a tapering and/or widening of the respective flow channel viewed in the flow direction of the medium.

The corrugated or groove-like depressions preferably have a linearly increasing or decreasing height in the catalyst plate.

Other advantageous embodiments of the invention are indicated in the subclaims.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 shows in cross section a catalytic element 2 for a flowing liquid or gaseous medium 4, in particular for the catalytic removal of nitrogen oxides from exhaust gases, for example flue gases, using ammonia gas. Another catalytic element 6 of similar construction is arranged below the first catalytic element 2 . In this case, in this embodiment, the outlet and inlet ports of the same size are arranged so as to overlap. However, it is also conceivable to use outlet ports and inlet ports of different sizes and/or to overlap the inlet port and the outlet port not directly on top of each other, but in a staggered manner.

The catalytic element 2 includes a large number of catalytic plates 8 and 10 arranged in parallel and impermeable to the fluidizing medium 4 . These are kept at a distance from each other in a frame that is not shown in detail. lij! I matching catalyst plate 8.1
It is important that the plates 0 are arranged at an angle to one another, so that a flow channel 12 or 14 for the flowing medium 4 is formed in each case between each plate, which diverges or tapers in the direction of flow. This widening or tapering is exaggerated in FIG. 1; normally the opening angle of the flow channel 12 or 14 is less than 5°.

The catalyst plates 8 and 10 are of approximately rectangular construction, as will be seen later in FIG.

The catalyst plate advantageously consists of a metal plate coated on both sides with a catalytically active substance. The tapering and widening of the flow channels 12.14 in this case has a clearly advantageous influence on the mass transport into the catalyst layer, i.e. onto the surface of the catalyst plate 8.10; the narrowing also accelerates the flow rate. Expansion means slowing down. As a result, turbulence occurs in the boundary layer at the surface, which improves the catalytic action. In particular, vortices also occur at the outlet of the catalytic element 2, ie also at the inlet of the catalytic element 6 connected downstream. Improved mixing therefore occurs at the entrance to the next, in this case the lower position of the catalyst plates 8a and 10a.

As is clear from FIG. 1, the catalyst plates 8.10 are inclined in opposite directions with respect to the flow direction of the medium 4. In principle, the separation and holding of the individual catalyst plates 8.10 is arbitrary. It can be secured by means. In this method it is advantageous to use corrugations that vary in height in the flow direction.

Such spacing elements are easy to manufacture and ensure reliable retention. In other words, correspondingly contoured corrugations are provided in all catalyst plates 8, 10 in order to taper or widen the respective flow channel 12.14. In this case, corrugation means heavy longitudinal grooves. The structure of the waveform will be clarified below based on FIGS. 2 to 4.

FIG. 2 shows a catalyst plate 10 which includes one corrugation 16 in each edge area. In this case, both longitudinal grooves are 1
As is clear from this figure, the peaks of the longitudinal groove 16m, indicated by 6m and 16n, decrease linearly in the longitudinal direction from the upper edge of the plate, while the peaks of the longitudinal groove 16n increase linearly in the longitudinal direction. ing. This is especially clear from FIG. In other words, the peaks of the corrugations 16 decrease in the longitudinal direction of the catalyst plate 10 on one side and increase in the longitudinal direction on the other side.

FIG. 4 is a plan view of the catalyst element 2 viewed from above.

Devices for joining or stacking and holding the individual catalyst plates 8 and 10 are not shown. It is important that the corrugations 16 (or 1) of adjacent catalyst plates 10 (or 8) are arranged in such a way that they are in contact with each other. It is. To be more precise, a longitudinal groove of 16m, 16n or 18m
, 13H are connected to the adjacent catalyst plate 8 in a flat range.
or in contact with 10. In this case, from the viewpoint of stability, the contact lines of the longitudinal grooves 18m, 18n of the catalyst plate 8 at a flat place, for example, at a flat place of the catalyst plate 10, should be close to each other, as clearly shown in FIG. It can be treated as such. The exact structure or mold can then be selected in such a way that, as far as possible, only one plate mold is produced for both inclined positions during its production.

Furthermore, it can be seen from FIG. 4 that the corrugations 16, 18 of adjacent catalyst plates 10 or 8 are arranged offset from one another in the width direction. This contributes to the stability mentioned above.

It is clear from FIG. 4 that the catalyst shaped body 2 has a number of tapered inlets and a number of enlarged inlets. The same can be said of the discharge ports. The stacking of the individual catalyst molded bodies 2.6 is based on the embodiment shown in the m1 diagram, so that a discharge port of substantially the same size is placed in the same size of another molded body 6. It is carried out by being connected to the inlet of the

[Brief explanation of drawings]

1 is a cross-sectional view of two stacked catalyst elements according to the invention, and FIG. 2 is a cross-sectional view of a catalyst plate with two corrugations consisting of longitudinal grooves of decreasing height and longitudinal grooves of increasing height. 3 is a sectional view of the catalyst plate along the line ■-■ of FIG. 2; FIG. 4 is a plan view of the catalyst element demonstrating the enlarged and reduced flow inlets of the individual flow channels; FIG. It is. 2.6... Catalyst element 4... Fluid medium 8.10... Catalyst plate 12.14... Flow channel 16.18... Waveform

Claims (1)

Claims: 1) Catalytic element for a flowing liquid or gaseous medium (4) having a number of medium-impermeable catalyst plates (8, 10) arranged in parallel and spaced apart from one another. (2) at least two adjacent catalyst plates (8, 10
) are arranged at an angle to each other, and a medium (4
Catalytic element for liquid or gaseous media, characterized in that the flow channels (12, 14) for the flow channels (12, 14) are tapered or diverging. 2) Catalytic element according to claim 1, characterized in that the catalyst plates (8, 10) are inclined in opposite directions when viewed transversely to the flow. 3) In order to configure the flow channels (12, 14) in a tapering or diverging manner, correspondingly shaped corrugations are formed in the catalyst plates (8, 10).
Or the catalyst element according to 2. 4) Catalytic element according to claim 3, characterized in that the crests of the corrugations (16) in the catalyst plates (8, 10) are linearly smaller or larger in their longitudinal direction. 5) Corrugations (16) in one catalyst plate (8, 10)
5. The catalytic element according to claim 3, wherein the peaks are larger in the longitudinal direction on one side and smaller in the longitudinal direction on the other side. 6) Corrugations (16, 8) of adjacent catalyst plates (10, 8)
Claim 3 characterized in that 18) are in contact with each other.
6. The catalyst element according to any one of items 5 to 5. 7) Corrugations (16, 8) of adjacent catalyst plates (10, 8)
7. Catalytic element according to claim 3, characterized in that the catalyst elements 18) are arranged in a staggered manner. 8) Catalytic element according to one of claims 1 to 7, characterized in that the opening angle of the flow channels (12, 14) is less than 5°. 9) A further element (6) having a tapered flow channel and a diverging flow channel (12a, 14a) is arranged above or below it. 1. Catalytic element according to item 1. 10) Catalytic element according to claim 9, characterized in that the tapered outlet is connected to the tapered inlet of another element (6).