WO2011020200A1

WO2011020200A1 - Static mixer and its use, f. ex. for catalytic denitrification of exhaust gases and the like

Info

Publication number: WO2011020200A1
Application number: PCT/CH2009/000272
Authority: WO
Inventors: Bernhard Hug; Carlos Hutmacher; Andreas Tschenett
Original assignee: Flowtech Industries Ag
Priority date: 2009-08-18
Filing date: 2009-08-18
Publication date: 2011-02-24
Also published as: CH702279B8; CH702279B1

Abstract

A static mixer (10, 20, 30, 40, 50, 60), especially for mixing a first fluid with a second fluid and/or with solid matter, with at least one basic unit (100, 200, 300, 500), wherein the basic unit comprises at least two main baffles (1 10, 120, 130, 140) of rectangular trapezoidal shape is characterised in that the four main baffles (110, 120, 130, 140) of the basic unit (100) are arranged in a star like manner and each of the four main baffles (110, 120, 130, 140) is tilted with respect to the first plane by a tilt angle (110.1, 120.1, 130.1, 140.1 ) greater than 0° and smaller that 90°.

Description

STATIC MIXER AND ITS USE, F . EX . FOR CATALYTIC DENITRIFICATION OF

EXHAUST GASES AND THE LIKE

Technical Field

The invention relates to a static mixer, especially for mixing a first fluid with a second fluid and/or with solid matter, with at least one basic unit, wherein the basic unit comprises at least two, preferably four, main baffles of rectangular trapezoidal shape, with each of the main baffles featuring a long parallel side and a short parallel side being in parallel to each other, a perpendicular side being perpendicular to the two parallel sides, an oblique side, a primary rectangular corner at an intersection of the long parallel side and the perpendicular side, an acute angled corner at an intersection of the long parallel side and the oblique side, and an obtuse angled corner at an intersection of the short parallel side and the oblique side. Furthermore, the invention relates to the use of a static mixer. Background Art

In many industrial processes fluids have to be guided through channels, ducts or runners. Depending on the actual conditions, the flow of a fluid may be very non-uniform with respect to its velocity, temperature, or composition. However, in lots of processes it is necessary to have uniform flow conditions of the fluids involved. In order to increase or establish uniform flow conditions, channels, ducts or runners are therefore typically equipped with so called static mixers.

A static mixer is a device for mixing flowing fluids and essentially comprises a number of baffles or blades construed for deflecting the flowing fluids. The deflection of the flowing fluids results in an intermixing of the fluids downstream of the static mixer. In contrast to dynamic mixers, static mixers do usually not feature mechanically moveable elements. Fluids that can be mixed with a static mixer may be gaseous and/or liquid and may additionally contain solid matter, for example dust and/or solid other particles.

The German patent specification DE 103 24 886 A1 (Framatome ANP GmbH) discloses for example a static mixer whereby a number of mixing blades are arranged around a central axis. Thereby, neighbouring mixing blades overlap in their projection on the normal plane of the central axis. The mixing blades may be of polygonal or trapezoidal shape.

However, many of the known static mixers produce violent vortices or turbulences. As a consequence, long sections of empty conduit are needed at the downstream side of the mixers in order to reach a homogeneous flow of the fluids. This in turn reduces the applicability of the mixer or demands for specifically adapted ducts, channels or runners. A further problem with known static mixers is the production of relatively high pressure drops.

Consequently, there is still need for an improved static mixer which does not entail the aforementioned drawbacks. Summary of the invention

It is therefore the object of the invention to provide a static mixer with enhanced mixing properties which is furthermore flexible in application.

The solution of the invention is specified by the features of claim 1. According to the invention the main baffles of the basic unit are arranged in a propeller like manner, whereby each of the long parallel sides of the four main baffles lies in a first plane, with each of the four primary rectangular corners of the four main baffles meeting at a central juncture in the first plane, and each of the four main baffles being tilted with respect to the first plane by a tilt angle greater than 0° and smaller that 90°. Within the context of the invention, the term baffle in particular stands for a plate for deflecting a flowing fluid. Preferably, the baffle or the plate is flat. In particular and if not stated otherwise, all of the sides of the baffle are essentially straight. However, corners of the baffle may optionally be rounded, if desired. Especially, the baffle is made of metal, metal alloy, plastic material, composite material and/or ceramic. The choice of material for the baffle is in particular adapted to the intended use of the static mixer. As well, dimensions of the baffles or the basic units and also the number and arrangement of the basic units are usually adapted for a specific application.

The first plane of the inventive mixer is usually to be arranged in a direction downstream with respect to the fluids to be mixed. If the mixer is for example arranged in an elongate duct and/or channel, the first plane of the mixer is preferably oriented perpendicular to a longitudinal axis of the duct or channel, respectively.

The fluids to be mixed with the inventive mixer are mainly gaseous and/or liquid and may additionally contain solid matter, such as dust and/or solid particles.

Compared to known static mixers, the inventive mixer features a similar goodness of mixture but at the same time turbulences are significantly reduced. When mixing fluids with the inventive static mixer, a highly homogeneous velocity profile is produced at the downstream side of the mixer. The same holds when mixing fluids containing solid matter, such as fluids with dust and/or solid particles. A homogeneous velocity distribution is already reached at a distance of 1 - 2 times a hydraulic diameter of a duct in which the inventive mixer is installed. Unlike with known mixers, there is no need for long sections of empty conduit at the downstream side of the inventive mixer to reach the desired homogeneous velocity distribution. This makes the inventive mixer very flexible in application since it may be installed even when the space available is limited, such as e. g. in short ducts or channels.

As a further advantage, the velocity profile of the fluids to be mixed at the upstream side of the inventive mixer does hardly have an effect on the mixing behaviour. That is to say, there is no need to adjust the velocity profile of the fluids to be mixed at the upstream side by additional equipment.

Compared to known static mixers with similar goodness of mixture, the inventive mixer furthermore features a significantly reduced pressure drop.

Because of the reduced turbulences, erosion due to high particle and/or dust concentration in the fluids is considerably reduced. Therefore, the inventive mixer is very well suited for mixing fluids with high concentrations of dust and/or particles, such as exhaust gases from power plants operated with fossil fuels. The inventive mixer is especially suitable for mixing gaseous fluids, whereby the gaseous fluids contain dust and/or solid particles. Thereby, the inventive mixer does not give rise to dust and/or particle deposit. Specifically, the inventive mixer may be used in connection with apparatus for flue gas denitrification (DeNOx) by use of selective catalytic reductions (SCR). Hereby, exhaust gases comprising nitrogen oxides (NO_x) and a high concentration of dust have to be mixed with ammonia (NH₃). As well, the inventive mixer is highly suitable for applications in coal fired power plants.

It has been found that the inventive arrangement of at least one basic unit with at least two, preferably four, main baffles of rectangular trapezoidal shape is very beneficial for a broad range of applications. By adjusting shape, size and tilt angles of the baffles in the basic unit, the mixing behaviour, the goodness of mixing, the pressure drop and the formation of turbulences can be controlled in a broad range. It is to be noted, that each of the main baffles may in principle have an individual size, shape and/or tilt angle. Consequently, the inventive mixer is very flexible in application. In practise, the optimal arrangement or embodiment of the baffles is preferably adapted to the specific use. In general, small tilt angles give rise to a larger pressure drop while large tilt angles reduce the efficiency of mixing.

Specifically, the inventive mixer can be adapted to a various ducts and/or channels with different cross sections. For example, the inventive mixer may be configured for ducts and/or channels with round or circular cross sections. Alternatively, it is possible to configure the inventive mixer for ducts and/or channels with polygonal, rectangular and/or square cross sections.

Preferably, a maximum width and/or diameter of the inventive static mixer in the first plane is about 0.1 - 20 m.

The choice of material for the baffles is especially adapted to the intended use of the static mixer. In principle, each of the main baffles may be made of a different material. However, it is in general more economical to make all the baffles in the basic unit from a single material. It is to be understood, that the material for the baffles has to be compatible with the fluids to be mixed.

According to the invention, the main baffles of the basic unit are arranged in a star like and/or propeller like manner with each of the primary rectangular corners of the main baffles meeting at a central juncture. At the central juncture, the main baffles may be welded together directly. Alternatively, the basic unit or the static mixer may at least partially be formed as a single piece, e. g. by moulding techniques, with the central juncture integrated. As well, it is possible to interconnect the main baffles at the central juncture with a separate connecting element.

In comparison with known static mixers, the inventive mixer can be produced cheaper. At the same time the inventive mixer features enhanced mixing properties and is furthermore highly flexible in application.

In a preferred embodiment, the basic unit comprises at least four, preferably exactly four, main baffles. By increasing the number of main baffles, the goodness of mixture can in general be increased. A number of exactly four man baffles turned out to be ideal for a wide range of applications. Thereby, a high goodness of mixture is achieved while at the same time the pressure drop is low.

However, more or less than four main baffles may be advantageous for specific applications. Preferably, each of the short parallel sides of the main baffles lies in a second plane, whereby the second plane being plane parallel to the first plane and offset from the first plane. The second plane is usually to be arranged in a direction upstream with respect to the fluids to be mixed. Thereby, preferably, all of the main baffles are arranged between the first and the second plane. Especially, the lengths of the perpendicular sides of the tilted main baffles are longer than a distance between the first and the second plane, measured in a direction perpendicular to the first and the second plane. As it has shown, such an arrangement of the main baffles improves the above mentioned advantages and properties of the inventive mixer further.

However, for specific applications it may be beneficial to have the short parallel sides of the main baffles to be arranged in different planes.

Especially, tilt angles of the main baffles are from 20° to 60°, in particular from 30° to 50°. Such tilt angles have been proven to be suitable for a wide variety of applications investigated by the inventors.

Nevertheless, tilt angles of the main baffles of less than 20° or more than 60° may be advantageous for specific applications.

Advantageously, at least two of the main baffles are congruent. In a preferred embodiment, the basic unit comprises two pairs of main baffles of equal size and shape. In particular, all of the main baffles are equal in size and shape. In a further preferred embodiment, the basic unit comprises four main baffles whereby, preferably, all of the four main baffles are equal in size and shape and tilted by the same tilt angle with respect to the first plane.

In particular, such arrangements with at least two main baffles being of the same size and shape help to improve the homogeneity of the velocity distribution in the fluids. Furthermore, the production of the inventive mixer is simplified because the amount of different parts is reduced.

However, all of the main baffles may be of different size and shape if desired for specific applications. In a preferred embodiment of the invention, long parallel sides of main baffles being diagonally opposed with respect to the central juncture are arranged in parallel to each other. Especially, the long parallel sides of main baffles being diagonally opposed with respect to the central juncture are arranged on a common straight line. Further preferred, main baffles being diagonally opposed with respect to the central juncture are of equal size and shape and tilted with respect to the first plane by the same tilt angle. Additionally or alternatively, obtuse angled corners of main baffles being diagonally opposed with respect to the central juncture are preferably arranged away form the central juncture and away form each other. Such arrangements simplify the structure of the inventive mixer and in practise it has been shown that mixing properties of the inventive mixer are increased. It is, however, within the invention to choose a different arrangement of the main baffles. For specific applications, main baffles being diagonally opposed with respect to the central juncture may for example be arranged under an oblique angle to each other.

Furthermore, it may be beneficial when long parallel sides of neighbouring main baffles are arranged perpendicular to each other. This again simplifies the structure of the inventive mixer. Though, it is as well possible to have a different arrangement with neighbouring main baffles arranged under an oblique angle to each other.

Especially, neighbouring main baffles are of different size and shape and tilted with respect to the first plane by different tilt angles. In this case, the basic unit comprises at least two types of different main baffles which furthermore are arranged under different tilt angles. In practise, static mixers with such an arrangement are especially advantageous in connections with ducts and/or channels with polygonal and/or rectangular cross sections. Furthermore, neighbouring main baffles which are of different size and shape and tilted with respect to the first plane by different tilt angles have been shown to have improved mixing properties for a wide range of applications. Nonetheless, it is well within the invention to foresee an arrangement with neighbouring main baffles being of equal size and shape and/or tilted with respect to the first plane by equal tilt angles.

In a particularly advantageous embodiment, at least one of the main baffles is mitred connected at its oblique side with at least one outer baffle, whereby the at least one outer baffle is sticking out of a plane of said at least one main baffle. In other words, in that case, the at least one outer baffle and the at least one of the main baffles are adjacent and connected to each other at the oblique side of the at least one of the four main baffles at an angle. Thereby, the plane of the at least one outer baffle and the plane of the at least one of the main baffles are not plane parallel to each other.

Especially, the at least one outer baffle is formed integrally with the at least one main baffle. In other words, the at least one outer baffle and the at least one main baffle are formed as one piece in that case. Alternatively, the at least one outer baffle and the at least one main baffle are separate parts which are interconnected with each other, e. g. by welding, gluing and/or with a separate fastening element. Thereby, the at least one outer baffle and the at least one main baffle may be formed from different materials.

In particular, each of the main baffles is mitred connected at its oblique side with an individual outer baffle. The basic unit especially comprises four main baffles and four outer baffles whereby each of the four outer baffles is mitre connected with the oblique side of one if the four main baffles.

Due to the at least one outer baffle, the above mentioned mixing properties of the inventive mixer are further enhanced.

However, it is still within the invention to have differently arranged outer baffles or no outer baffle at all connected to a main baffle. In a preferred embodiment of the invention, the at least one outer baffle is flat and features two straight sides and a curved side. In another preferred embodiment, each of the main baffles is mitred connected at its oblique side with an outer baffle that is flat and features two straight sides and a curved side. Outer baffles which are flat and feature two straight sides and a curved side are especially suitable for mounting the inventive mixer in a duct and/or channel with at least partially round side walls or with round cross sections. Thereby, the curved side of the outer baffle can be formed to fit with the partially round sidewalk If each of the four main baffles is mitred connected at its oblique side with an outer baffle that is flat and features two straight sides and a curved side, it is even possible to produce a mixer with an elliptical or circular envelope in a projection on the first plane.

Alternatively or additionally, the at least one outer baffle is of rectangular trapezoidal shape, featuring a long parallel side and a short parallel side being in parallel to each other, a perpendicular side being arranged perpendicular to the short parallel side and the long parallel side, an oblique side, a primary rectangular corner at an intersection of the long parallel side and the perpendicular side, an acute angled corner at an intersection of the long parallel side and the oblique side, and an obtuse angled corner at an intersection of the short parallel side and the oblique side.

Preferably, the at least one outer baffle is mitred connected at its oblique side with the main baffle mitred connected with said at least one outer baffle. A length of the oblique side of the at least outer baffle is in particular equal to a length of the oblique side of the main baffle mitred connected with said at least one outer baffle.

In an especially preferred embodiment, each of the main baffles is mitre connected at its oblique side with an individual outer baffle of rectangular trapezoidal shape. Preferably, the basic unit especially comprises four main baffles and four outer baffles of rectangular trapezoidal shape whereby each of the four outer baffles is mitred connected at its oblique side with the oblique side of one if the four main baffles. Thereby, the four outer baffles may in principle be of different size and shape.

The combination of outer baffles of rectangular trapezoidal shape mitred connected with main baffles have shown to significantly enhance the above mentioned mixing properties of the inventive mixer further. However, it is still within the invention to have a different arrangement of the outer baffles or to have differently shaped outer baffles.

According to a further preferred embodiment, the long parallel side of the at least one outer baffle lies in the first plane of the basic unit and the short parallel side of the at least one outer baffle lies in the second plane of the basic unit and additionally, the at least one outer baffle is tilted with respect to the first plane by a tilt angle greater than 0° and smaller that 90°. Thereby, the at least one outer baffle is arranged between the first and the second plane. Especially, the length of the perpendicular side of the tilted outer baffle is longer than a distance between the first and the second plane, measured in the direction perpendicular to the first and the second plane.

Especially, the long parallel sides of the at least one outer baffle is perpendicular to the long parallel side of the main baffle mitred being connected with said at least one outer baffle. As well, in particular, the short parallel side of the at least one outer baffle is perpendicular to the short parallel side of the main baffle being mitred connected with said outer baffle. In case of more than one outer baffle, it is advantageous to have all of the outer baffles arranged in this manner.

In practise, such an arrangement of the at least one outer baffles has shown to considerably improve the mixing properties of the inventive mixer further in a broad range of applications. Furthermore, in such an embodiment the inventive mixer can be built very compact without any elements sticking out of the first in downstream direction or of the second plane in upstream direction.

However, for specific applications it may be beneficial to have the long parallel and/or the short parallel side of the at least one outer baffle arranged differently. E. g., it is thinkable to have the long parallel and/or the short parallel side of the at least one outer baffle sticking out of the first or second plane. As well the long parallel and/or the short parallel side of the at least one outer baffle the may be arranged under an oblique angle to the long parallel side of the main baffle mitred being connected with said at least one outer baffle.

Preferably, the basic unit comprises at least two outer baffles which are of equal size and shape. Further preferred, the basic unit comprises at least two outer baffles which are equal in size and shape with two of the main baffles. Thereby, especially, outer baffles being diagonally opposed with respect to the central juncture are of equal size and shape and tilted with respect to the first plane by the same tilt angle. In another preferred embodiment, all of the baffles of the basic unit, namely the main baffles and the outer baffles, are of equal size and shape and tilted with respect to the first plane by the same tilt angle. Such arrangements have proven to be advantageous in connection with ducts and/or channels with square cross sections.

In another preferred embodiment, outer baffles being connected to neighbouring main baffles are of different size and shape and tilted with respect to the first plane by different tilt angles. In practise, static mixers with such an arrangement are especially advantageous in connections with ducts and/or channels with polygonal and/or rectangular cross sections.

Tests have shown that arrangements with at least two of the outer baffles being of equal size and shape help to improve the mixing properties in general. Furthermore, the use of baffles of equal size and shape simplifies the production and structure of the inventive mixer because the amount of differently formed parts is reduced.

However, all of the outer baffles may be of different size and shape and/or of different materials if desired for specific applications.

Particularly advantageous, in a projection on the first plane, the basic unit features a swastika like shape and/or a cross like structure with arms bent at right angles. Further preferred, in a projection on the first plane, all of the main baffles and/or all of the outer baffles of the basic unit are without any overlap.

As tests have shown, such an arrangement considerably improves the mixing behaviour, the goodness of mixing and at the same time reduces the pressure drop and the formation of turbulences. However, for specific applications other arrangements may be beneficial.

In another advantageous embodiment, the inventive mixer comprises several basic units, whereby, preferably all of the first planes of the several basic units being coplanar and further preferred, all of the basic units being of similar structure. With such an embodiment, it is possible to further adapt the inventive static mixer to specific applications in a rather easy way. In practise, arranging all of the first planes of the several basic units coplanar has been proven to be optimal for a wide range of applications. The use of similar basic units further simplifies the structure and production of the mixer. For example, it is possible to build relatively large mixers of almost any desired shape by simply putting together several similar basic units. This makes the inventive mixer very flexible in application.

However, it may be beneficial to put together basic units with different structures and/or in a different arrangement. In particular, basic units located at the edge of a mixer, may be different form basic units in the central region of the mixer. For example, outer baffles of the basic units located at the edge of a mixer may be specifically adapted to the form of a side wall of a duct and/or channel.

Especially, an obtuse angled corner of one of the main baffles of the at least one basic unit is interconnected with an obtuse angled corner of one of the main baffles of a neighbouring basic unit. If at least one outer baffle of rectangular trapezoidal shape is present in each of the interconnected basic units, a primary rectangular corner of one of the outer baffles of the at least one basic unit is preferably interconnected with a primary rectangular corner of one of the outer baffles of the neighbouring basic unit.

Such interconnections between the basic units have shown to be in particular advantageous in order to improve the mixing properties of the inventive mixer. However, other interconnections of the basic units are possible if desired for specific applications.

Preferably, in a projection on the first plane, all of the basic units are without any overlap in an arrangement of several basic units. As tests have shown, such an arrangement considerably improves the mixing behaviour, the goodness of mixing and at the same time reduces the pressure drop and the formation of turbulences.

For specific applications it is however possible to deviate from this arrangement and to provide a mixer with overlapping basic units.

Especially, the inventive static mixer is mounted in a duct and/or channel. In particular, the duct or channel is a gas conducting duct of a power station operated with fossil fuels. Alternatively or additionally, the duct may be a flue gas conducting duct of an apparatus for flue gas denitrification (DeNOx) by use of selective catalytic reductions (SCR).

Especially, when mounting the inventive mixer in a duct and/or channel, the first plane of the static mixer is in particular oriented perpendicular to a longitudinal direction of the duct, preferably with the first plane oriented downstream and/or the second plane oriented upstream. Further preferred, a size and a shape of the inventive mixer are adapted such that the static mixer covers all of a cross section of the duct.

However for specific applications it may be beneficial deviate from such an arrangement in the duct or channel and/or to adapt the inventive mixer such that only a part of the cross section of the duct and/or channel is covered. Furthermore, it is possible to equip a duct and/or channel with several of the inventive mixers in parallel and/or in series.

Other advantageous embodiments and combinations of features come out from the detailed description below and the totality of the claims. Brief description of the drawings

The drawings used to explain the embodiments show:

Fig. 1 A perspective view of a first static mixer consisting of four trapezoidal main baffles in a propeller like arrangement;

Fig. 2 A plan view on downstream side of the static mixer of Fig. 1 ; Fig. 3 A side view of the static mixer of Fig. 1 - 2;

Fig. 4 A perspective view of a second static mixer consisting of four trapezoidal main baffles in a propeller like arrangement with four rounded outer baffles;

Fig. 5 A plan view on downstream side of the static mixer of Fig. 4;

Fig. 6 A side view of the static mixer of Fig. 4 - 5; Fig. 7 A perspective view of a third static mixer consisting of four trapezoidal main baffles in a propeller like arrangement with four trapezoidal outer baffles;

Fig. 8 A plan view on the downstream side of a fourth static mixer consisting of four interconnected basic units of the third static mixer of Fig. 7; Fig. 9 A perspective view of the fourth static mixer of Fig. 8;

Fig. 10 A side view of the static mixer of Fig. 8 - 9;

Fig.1 1 A cross section of the fourth static mixer of Fig. 8 - 10 mounted in a duct;

Fig. 12 A longitudinal section of the arrangement of Fig. 1 1 along the line A - A; Fig. 13 A plan view on the downstream side of a fifth static mixer consisting of two different pairs of trapezoidal main baffles in a propeller like arrangement with two different pairs of trapezoidal outer baffles;

Fig. 14 A perspective view of a sixth static mixer consisting of nine interconnected basic units of the fifth static mixer of Fig. 13; Fig. 15 A plan view on the downstream side of a sixth static mixer of Fig. 14;

Fig. 16 A side view of the static mixer of Fig. 14 - 15.

Preferred embodiments

Figures 1 - 3 show schematic representations of a first static mixer 10 consisting of a single basic unit 100. The basic unit 100 comprises a first main baffle 1 10, a second main baffle 120, a third main baffle 130 and a fourth main baffle 140. Each of the four main baffles 1 10, 120, 130, 140 is flat and of rectangular trapezoidal shape. The material and dimensions of the main baffles 1 10, 120, 130, 140 depend on the intended use or application of the static mixer.

Thereby, the first main baffle 1 10 features a long parallel side 1 1 1 and a short parallel side 1 12 being in parallel to each other. Furthermore, the first baffle comprises a perpendicular side 1 13, being perpendicular to the two parallel sides 1 1 1, 1 12, and an oblique side 1 14.

A primary rectangular corner 1 15 of the first baffle 1 10 is located at the intersection of the long parallel side 1 1 1 and the perpendicular side 1 13. A secondary rectangular corner 1 16 is located at the intersection of the short parallel side 1 12 and the perpendicular side 1 13. Additionally, an acute angled corner 1 17 is located at the intersection of the long parallel 1 1 1 side and the oblique side 1 14 while an obtuse angled corner 1 18 is located at the intersection of the short parallel side 1 12 and the oblique side 1 14.

The second main baffle 120, the third main baffle 130 and the fourth main baffle 140 are essentially identical in construction with the first main baffle 1 10. The four main baffles 1 10, 120, 130, 140 are arranged around a central juncture 101 in a star like or propeller like manner with their acute angled corners 1 17, 127, 137, 147 pointing outwards. Specifically, the primary rectangular corner 1 15 of the first baffle 1 10, the primary rectangular corner 125 of the second baffle 120, the primary rectangular corner 135 of the third baffle 130 and the primary rectangular corner 145 of the fourth baffle 140 are interconnected at the central juncture 101. Furthermore, the long parallel side 1 1 1 of the first baffle 1 10 is perpendicular to the long parallel side 121 of the second baffle 120. Similarly, the long parallel side 131 of the third baffle 130 is perpendicular to the long parallel side 121 of the second baffle 120. The long parallel side 141 of the fourth baffle 140 is perpendicular to the long parallel side 131 of the third baffle 130. Consequently, long parallel sides of baffles being diagonally opposed with respect to the central juncture 101 are parallel to each other while long parallel sides of neighbouring baffles are perpendicular.

Similarly, the short parallel side 1 12 of the first baffle 1 10 is perpendicular to the short parallel side 122 of the second baffle 120. Correspondingly, the short parallel side 132 of the third baffle 130 is perpendicular to the short parallel side 122 of the second baffle 120. The short parallel side 142 of the fourth baffle 140 is perpendicular to the short parallel side 132 of the third baffle 130. Consequently, short parallel sides of baffles being diagonally opposed with respect to the central juncture 101 are parallel to each other while short parallel sides of neighbouring baffles are perpendicular. Additionally, all of the long parallel side 1 1 1, 121 , 131, 141 are comprised in a first plane 102 of the first mixer 100 and all of the short parallel side 1 12, 122, 132, 142 are comprised in a second plane 103 of the first mixer 100. The two planes 102, 103 are offset and plane parallel to each other. All of the four baffles 1 10, 120, 130, 140 of the first mixer 10 are tilted with respect to the first plane 102. Thereby, the first tilt angle 1 10.1 of the first baffle 1 10 is for example about 40°. The second tilt angle 120.1 of the second baffle 120, the third tilt angle 130.1 of the third baffle 130 and the fourth tilt angle 140.1 of the fourth baffle 140 are equal to the first tilt angle 140.1.

When e. g. mounted in a duct, the first plane 102 is preferably oriented perpendicular to a longitudinal axis of the duct and downstream with respect to the flowing fluid. Accordingly, the second plane 103 is preferably oriented upstream.

Figure 4 - 6 show schematic representations of a second static mixer 20 consisting of a single basic unit 200. The second mixer 200 comprises a first main baffle 210, a second main baffle 220, a third main baffle 230 and a fourth main baffles 240 whereby the four main baffles 210, 220, 230, 240 of the second mixer are essentially identical to the four main baffles 1 10, 120, 130, 140 of the first mixer 10 shown in Fig. 1 - 3. Furthermore, the arrangement of the four main baffles 210, 220, 230, 240 around the central juncture 201 of the second mixer 200 is essentially identical with the first mixer 10. As it is the case in the first mixer 10, the long parallel sides 21 1, 221 , 231, 241 of the four main baffles 210, 220, 230, 240 are comprised in a first plane 202 while all of the short parallel sides 212, 222, 232, 242 of the four main baffles 210, 220, 230, 240 are comprised in a second plane 203 with the two planes 202, 203 being offset and plane parallel to each other. Contrary to the first mixer 10, the first main baffle 210 of the second mixer 200 is mitred connected at its oblique side 214 with a first outer baffle 250. The first outer baffle 250 is a flat plate of triangular shape, comprising a first and long straight side 251, a second and short straight side 252 as well as a curved side 253.

The first outer baffle 250 is mitred connected along its long side 251 with the oblique side 214 of the first main baffle 210. The long side 251 of the outer baffle 250 and the oblique side 214 of the first main baffle 210 are of the same length and arranged in parallel to each other. Furthermore, the first outer baffle 250 is sticking out of the plane of the first main baffle 210. Hereby, the short side 252 of the first outer baffle 250 is contained in the second plane 203. The short side 252 of the first outer baffle 250 is arranged perpendicular to the short parallel side 212 of the first main baffle 210. Moreover, the first outer baffle 250 is tilted with respect to the first plane 202 by a first outer tilt angle 250.1 of e. g. 40°.

Similarly, the second main baffle 220 of the second mixer 20 is mitred connected at its oblique side 224 with a second outer baffle 260. The second outer baffle 260 is mitred connected along its long side 261 with the oblique side 224 of the second main baffle 220. The long side 261 of the second outer baffle 260 and the oblique side 224 of the second main baffle 220 are of the same length and arranged in parallel to each other. Furthermore, the second outer baffle 260 is sticking out of the plane of the second main baffle 220. Hereby, the short side 262 of the second outer baffle 260 is contained in the second plane 203. The short side 262 of the second outer baffle 260 is arranged perpendicular to the short parallel side 222 of the second main baffle 220. Moreover, the second outer baffle 260 is tilted with respect to the first plane 202 by a second outer tilt angle 260.1 of e. g. 40°.

As well, the third main baffle 230 of the second mixer 20 is mitred connected at its oblique side 234 with a third outer baffle 270. The third outer baffle 270 is mitred connected along its long side 271 with the oblique side 234 of the third main baffle 230. The long side 271 of the third outer baffle 270 and the oblique side 234 of the third main baffle 230 are of the same length and arranged in parallel to each other. Furthermore, the third outer baffle 270 is sticking out of the plane of the third main baffle 230. Hereby, the short side 272 of the third outer baffle 270 is contained in the second plane 203. The short side 272 of the third outer baffle 270 is arranged perpendicular to the short parallel side 232 of the third main baffle 230. Moreover, the third outer baffle 270 is tilted with respect to the first plane 202 by a third outer tilt angle 270.1 of e. g. 40°.

Finally, the fourth main baffle 240 of the second mixer 20 is mitred connected at its oblique side 244 with a fourth outer baffle 280. The fourth outer baffle 280 is mitred connected along its long side 281 with the oblique side 244 of the fourth main baffle 240.

The long side 281 of the fourth outer baffle 280 and the oblique side 244 of the fourth main baffle 240 are of the same length and arranged in parallel to each other.

Furthermore, the fourth outer baffle 280 is sticking out of the plane of the fourth main baffle 240. Hereby, the short side 282 of the fourth outer baffle 280 is contained in the second plane 203. The short side 282 of the fourth outer baffle 280 is arranged perpendicular to the short parallel side 242 of the fourth main baffle 240. Moreover, the fourth outer baffle 280 is tilted with respect to the first plane 202 by a fourth outer tilt angle 280.1 of e. g. 40°. Thereby, all of the four outer baffles 250, 260, 270, 280 are essentially identical in construction.

As can best be seen in Fig. 5, in a projection on the first plane 202, the second mixer 20 features a swastika like structure with curved arms and a circular circumferential envelope. Moreover, there is no overlap between the baffles 210, 220, 230, 240, 250, 260, 270, 208 in a projection on the first plane 202.

Evidently, the second mixer 20 is especially suitable for ducts or channels with circular cross section.

Fig. 7 shows a schematic representation of a third static mixer 30 with a single basic unit 300. The third static mixer is essentially a modification of the second mixer 20. The third static mixer 30 comprises a first main baffle 310, a second main baffle 320, a third main baffle 330 and a fourth main baffle 340 whereby the four main baffles 310, 320, 330, 340 of the third mixer 30 are essentially identical to the four main baffles 210, 220, 230, 240 of the second mixer 20 shown in Fig. 4 - 6. As well, the arrangement of the four main baffles 310, 320, 330, 340 around the central juncture 301 of the third mixer 30 is essentially identical with the second mixer 20. As with the second mixer 20, the long parallel sides 31 1 , 321 , 331 , 341 of the four main baffles 310, 320, 330, 340 are comprised in a first plane 302 while all of the short parallel sides 312, 322, 332, 342 of the four main baffles 310, 320, 330, 340 are comprised in a second plane 303 with the two planes 302, 303 being offset and plane parallel to each other (see also Fig. 9 and 10). However, shape and size of the outer baffles 350, 360, 370, 380 of the third mixer 30 are different from the four outer baffles 250, 260, 70, 280 of the second mixer 20. Specifically, each of the four outer baffles 350, 360, 370, 380 of the third mixer 30 is of rectangular trapezoidal shape. The first outer baffle 350 features a long parallel side 351 and a short parallel side 352 being in parallel to each other. Furthermore, the first outer baffle 350 comprises a perpendicular side 353, being perpendicular to the two parallel sides 351, 352 and an oblique side 354. A primary rectangular corner 355 of the first outer baffle 350 is located at the intersection of the long parallel side 351 and the perpendicular side 353.

The second outer baffle 360, the third outer baffle 370 and the fourth outer baffle 380 are essentially identical in construction with the first outer baffle 350. In the third mixer 300, all of the main baffles 310, 320, 330, 340 and all of the outer baffles 350, 360, 370, 380 are of identical construction. In other words, all of the baffles 310, 320, 330, 340, 350, 360, 370, 380 of the third mixer 30 are of the same size and shape.

The first outer baffle 350 is mitred connected along its oblique side 354 with the oblique side 314 of the first main baffle 310. The oblique side 354 of the first outer baffle 350 and the oblique side 314 of the first main baffle 310 are of the same length and arranged in parallel to each other. Thereby, the obtused angled corner of the first main baffle 310 is adjacent to the obtused angled corner of the first outer baffle 350. Similarly, the acute angled corner 317 of the first main baffle 310 is adjacent to the acute angled corner of the first outer baffle 350.

Furthermore, the first outer baffle 350 is sticking out of the plane of the first main baffle 310. Hereby, the long parallel side 351 of the first outer baffle 350 is contained in the first plane 302. The long parallel side 352 of the first outer baffle 350 is arranged perpendicular to the long parallel side 31 1 of the first main baffle 310. As well, the short parallel side 352 of the first outer baffle 350 contained in the second plane 303 is furthermore perpendicular to the short parallel side 312 of the first main baffle 350. Moreover, the first outer baffle 350 is tilted with respect to the first plane 202 by the same tilt angle as the first main baffle 310, e. g. 40°.

Similarly, the second outer baffle 360 is mitred connected along its oblique side 364 with the oblique side 324 of the second main baffle 320 in the same manner as the first outer baffle 350 is mitred connected to the first main baffle 310. The same holds for third outer baffle 370 which is mitred connected along its oblique side 374 with the oblique side 334 of the third main baffle 330 and the fourth outer baffle 380 which is mitred connected along its oblique side 384 with the oblique side 344 of the fourth main baffle 340. Thereby, all of the long parallel sides 351, 361 , 371 , 381 of the outer baffles 350, 360, 370, 380 are arranged in the first plane 202 while all of the short parallel sides 352, 362, 372, 382 of the outer baffles 350, 360, 370, 380 are arranged in the second plane 203 of the third static mixer 30.

In a projection on the first plane 302, the third mixer 30 features a swastika like structure with a quadratic circumferential envelope. There is no overlap between the baffles 310, 320, 330, 340, 350, 360, 370, 380 in a projection on the first plane 302.

Obviously, the third mixer 30 is in particular suitable for ducts or channels with quadratic cross section.

Fig 8 - 10 show schematic representations of a fourth static mixer 40 consisting of four interconnected basic units 300a, 300b, 300c, 30Od. All of the four basic units 300a, 300b, 300c, 30Od are essentially identical in construction with the basic unit 300 of the third static mixer 30 shown in Fig. 7. In the fourth static mixer 40, the first basic unit 300a is interconnected at the acute angled corner 337a of the third main baffle 330a with the acute angled corner 317a of the first main baffle 310b of the second basic unit 300b. Additionally, the primary rectangular corner 365a of the second outer baffle 360a of first basic unit 300a is interconnected with the primary rectangular corner 355b of the first outer baffle 350b of the second basic unit 300b. Furthermore, the primary rectangular corner 375a of the third outer baffle 370a of the first basic unit 300a is interconnected with the primary rectangular corner 385b of the fourth outer baffle 380b of the second basic unit 300b. Hereby, all of the aforementioned interconnections are located in the first plane 302a of the first basic unit 300a. Moreover, the long parallel side of the third main baffle 330a of the first basic unit 300a and the long parallel side of the first main baffle 310b of the second basic unit 300b are both arranged on a common straight line.

Similarly, the second basic unit 300b is interconnected at the acute angled corner 347b of the fourth main baffle 340b with the acute angled corner 327c of the second main baffle 320c of the third basic unit 300c. Additionally, the primary rectangular corner 375b of the third outer baffle 370b of the second basic unit 300b is interconnected with the primary rectangular corner 365c of the second outer baffle 360c of the third basic unit 300c. Furthermore, the primary rectangular corner 385b of the fourth outer baffle 380b of the second basic unit 300b is interconnected with the primary rectangular corner 355c of the first outer baffle 350c of the third basic unit 300c. As well, all of the aforementioned interconnections are located in the first plane 302a of the first basic unit 300a. Moreover, the long parallel side of the fourth main baffle 340b of the second basic unit 300b and the long parallel side of the second main baffle 320c of the third basic unit 300c are both arranged on a common straight line. Likewise, the third basic unit 300c is interconnected at the acute angled corner 317c of the first main baffle 310c with the acute angled corner 337d of the third main baffle 33Od of the fourth basic unit 30Od. Additionally, the primary rectangular comer 385c of the fourth outer baffle 380c of the third basic unit 300c is interconnected with the primary rectangular comer 375d of the third outer baffle 37Od of the fourth basic unit 30Od. Furthermore, the primary rectangular corner 355c of the first outer baffle 350c of the third basic unit 300c is interconnected with the primary rectangular corner 365d of the second outer baffle 36Od of the fourth basic unit 30Od. Again, all of the aforementioned interconnections are located in the first plane 302a of the first basic unit 300a. Moreover, the long parallel side of the first main baffle 310c of the third basic unit 300c and the long parallel side of the third main baffle 33Od of the fourth basic unit 30Od are both arranged on a common straight line.

As well, the fourth basic unit 30Od is interconnected at the acute angled corner 327d of the second main baffle 32Od with the acute angled corner 347a of the fourth main baffle 340a of the first basic unit 300a. Additionally, the primary rectangular corner 355d of the first outer baffle 35Od of the fourth basic unit 30Od is interconnected with the primary rectangular corner 385a of the fourth outer baffle 380a of the first basic unit 300a. Furthermore, the primary rectangular corner 365d of the second outer baffle 36Od of the fourth basic unit 30Od is interconnected with the primary rectangular comer 375 a of the third outer baffle 370a of the first basic unit 300a. Once more, all of the aforementioned interconnections are located in the first plane 302a of the first basic unit 300a. Moreover, the long parallel side of the second main baffle 32Od of the fourth basic unit 30Od and the long parallel side of the fourth main baffle 340a of the first basic unit 300a are both arranged on a common straight line.

In other words, the four basic units 300a, 300b, 300c, 30Od are arranged side by side in two rows and two lines in a common plane which is the first plane 302a of the first basic unit 300a.

All of the baffles of the four basic units 300a, 300b, 300c, 30Od are essentially identical in construction and tilted by the same tilt angle with respect to the first plane 302a of the first basic unit 300a. In a projection on the first plane 302a of the first basic unit 300a, there is no overlap of the baffles in the fourth static mixer 40. Moreover, all of the long parallel sides of the main and the outer baffles are located in the first plane 302a of the first basic unit 300a while all of the short parallel sides of the main and outer baffles are located in the second plane 302a of the first basic unit 300a.

In a projection on the first plane 302a, the fourth mixer 40 features a quadratic circumferential envelope. There is no overlap between the baffles in the projection on the first plane 302a.

Fig. 1 1 represents a cross section of the fourth mixer 40 mounted in a hollow duct 41 with a quadratic cross section. Fig. 12 shows a corresponding longitudinal section of Fig. 1 1 along the line A - A. The fourth mixer 40 is mounted with the first plane 302a perpendicular to the longitudinal axis 42 of the duct 41. The first plane 302a is oriented downstream with respect to a flow of fluid 43 while the second plane 303a is oriented upstream. Essentially, the forth mixer 40 covers all of the ducts cross section.

Fig 13 shows a schematic representation of a fifth static mixer 50 with a single basic unit 500. The basic unit 500 consists of four main baffles 510, 520, 530, 540 and four outer baffles 550, 560, 570, 580 which all are of rectangular trapezoidal shape. The baffles of the basic unit 500 are arranged and interconnected similarly to the baffles of the basic unit 300 of the third static mixer 30 shown in Fig. 7.

However, in the basic unit 500 of the fifth static mixer 50, neighbouring main baffles are different in size and shape, while main baffles being diagonally opposed to each other with respect to the central juncture 501 are essentially identical in construction. Specifically, the long parallel side 51 1 of the first main baffle 510 is longer than the long parallel side 521 of the neighbouring second main baffle 520. As well the short parallel side 512 of the first main baffle 510 is longer than the short parallel side 522 of the second main baffle 520. The third main baffle 530, being diagonally opposed to the first main baffle 510 with respect to the central juncture 501, is of the same size and shape as the first main baffle 510. The fourth main baffle 540, being diagonally opposed to the second main baffle 520 with respect to the central juncture 501 , is of the same size and shape as the second main baffle 520.

The first outer baffle 550, which is mitred connected to the first main baffle 510, is of the same size and shape as the second main baffle 520. Furthermore, the second outer baffle

560, which is mitred connected with the second main baffle 520, is of the same size and shape as the first main baffle 510. The third outer baffle 570, which is mitred connected with the third main baffle 530, is again of the same size and shape as the second main baffle 520 or the first outer baffle 550. Finally, the fourth outer baffle 580, which is mitred connected with the fourth main baffle 540, is of the same size and shape as the first main baffle 510 or the second outer baffle 560. Consequently, the further basic unit 500 consist of two different types of baffles.

Similarly to the basic unit 300 of Fig. 7, all of the long parallel sides of the four main baffles 510, 520, 530, 540 and all of the long parallel sides of the four outer baffles 550, 560, 570, 580 are located in a first plane of the basic unit 500 while all of the short parallel sides of the four main baffles 510, 520, 530, 540 and all of the short parallel sides of the four outer baffles 550, 560, 570, 580 are located in a second plane (not shown in Fig. 13) of the basic unit 500. As with the basic unit 300 of Fig. 7, the first and the second plane are plane parallel and offset to each other. Tilt angles of baffles being of the same size and shape are identical, whereas tilt angles of baffles being different in size and shape are different. Moreover, oblique sides of baffles being mitred connected with each other are of equal length.

In a projection on the first plane, the further basic unit features an elongated swastika like structure with a rectangular circumferential envelope. There is no overlap between the baffles 510, 520, 530, 540, 550, 560, 570, 580 in a projection on the first plane. Fig 14 - 16 show schematic representations of a sixth static mixer 60 consisting of nine interconnected basic units. All of the nine basic units are essentially identical in construction with the basic unit 500 of the fifth static mixer 50 shown in Fig. 13. The nine basic units of the sixth static mixer 60 are arranged side by side in. three rows and three lines in a common plane. The interconnection between the basic units in the sixth static mixer 60 is essentially analogous to the fourth static mixer 40.

Tests of the aforementioned static mixers 10, 20, 30, 40, 50, 60 installed in ducts have shown that homogeneous velocity distributions of fluids to be mixed are already reached at a distance of 1 - 2 times of the hydraulic diameter of the duct. At the same time a high goodness of mixture was obtained in a broad range of different applications.

Especially, the inventive mixers have shown to be very well suited for mixing fluids with high concentrations of dust and/or particles, such as exhaust gases from power plants operated with fossil fuels. Specifically, the inventive mixers have shown to be very beneficial for mixing exhaust gases comprising nitrogen oxides (NO_x) and high concentrations of dust with ammonia (NH₃) in apparatus for selective catalytic reductions (SCR).

The invention is not restricted on the embodiments discussed above. In particular, it is for example possible to omit one or two or three of the main baffles 1 10, 120, 130, 140 in the first static mixer 10. A more simple static mixer may for example consist solely of two of the four main baffles 1 10, 120, 130, 140 of the first static mixer 10. A possible configuration for such a simple static mixer consists e. g. solely of the first main baffle 1 10 and the third main baffle 130 which are arranged diagonally opposed with respect to the central juncture 101. In this case, the second main baffle 120 and the fourth main baffle are omitted. Alternatively, another simple static mixer with two main baffles may for example consist solely of the first main baffle 1 10 and the neighbouring second main baffle 120. Consequently, the third main baffle 130 and the fourth main 140 baffle are omitted. Analogous, the same holds for the other static mixers 20, 30, 40, 50, 60, whereby an outer baffle mitred connected with an omitted main baffle is in particular left out as well. Alternatively or additionally, the static mixers 10, 20, 30, 40, 50, 60 may be equipped with additional baffles.

Moreover, in the first four static mixers 10, 20, 30, 40, one or more of the main baffles may be of different size and/or shape. Furthermore, one or more of the tilt angles may be different.

Generally, one or more of the outer baffles in the static mixers 20, 30, 40, 50, 60 may be replaced by differently shaped baffles or omitted. Furthermore, main baffles of the static mixers 20, 30, 40, 50, 60 may be equipped with more than one outer baffle.

In the fourth static mixer 40 and the sixth static mixer 60, the single basic units 300a, 300b, 300c, 30Od, 500 may as well be arranged offset from each other and/or in different planes. Of course, it is also possible to add additional basic units or to remove one or more of the basic units from the fourth static mixer 40 and/or the sixth static mixer 60. This allows for example to adapt the shape of the static mixer to ducts or channels with polygonal cross sections with more than four corners. The additional basic units do not necessarily have to be identical in construction with the other basic units. In contrary, it is unproblematic to build a static mixer out of several different basic units.

The outer baffles 350a, 360b, 370c, 38Od in the fourth static mixer 40 may for example be replaced by outer baffles with a curved side, e. g. an outer baffle of the second static mixer 20. Especially, this allows for mounting the fourth static mixer 40 in a duct with round corners. The same holds for the sixths static mixer 60.

Moreover, all of the static mixers 10, 20, 30, 40 may e.g. feature additional baffles and/or mounting fixtures.

In Fig. 1 1, the static mixer does not necessarily have to cover the whole cross section of the duct. Depending on the specific application, it could be beneficial to have a smaller static mixer which only covers part of the ducts cross section.

In summary, it is to be noted that a new kind of static mixer is provided which is very in particular very flexible in application. The inventive static mixers especially features a high goodness of mixture and simultaneously a mixing path as well as a pressure drop of the mixer are minimal.

Claims

1. A static mixer (10, 20, 30, 40, 50, 60), especially for mixing a first fluid with a second fluid and/or with solid matter, with at least one basic unit (100, 200, 300, 500), wherein the basic unit comprises at least two, preferably four, main baffles (1 10, 120, 130, 140) of rectangular trapezoidal shape, with each of the main baffles (1 10, 120,

130, 140) featuring a long parallel side (1 1 1, 121, 131, 141) and a short parallel side (1 12, 122, 132, 142) being in parallel to each other, a perpendicular side (1 13, 123,

133, 143) being perpendicular to the two parallel sides, an oblique side (1 14, 124,

134, 144), a primary rectangular corner (1 15, 125, 135, 145) at an intersection of the long parallel side (1 1 1, 121, 131 , 141) and the perpendicular side (1 13, 123, 133,

143), an acute angled corner (1 17, 127, 137, 147) at an intersection of the long parallel side (1 1 1, 121, 131 , 141) and the oblique side (1 14, 124, 134, 144), and an obtuse angled corner (1 18, 128, 138, 148) at an intersection of the short parallel side (1 12, 122, 132, 142) and the oblique side (1 14, 124, 134, 144), characterized in that the main baffles (1 10, 120, 130, 140) of the basic unit (100) are arranged in a propeller like manner, whereby each of the long parallel sides (1 1 1 , 121, 131, 141) of the main baffles (1 10, 120, 130, 140) lies in a first plane (102), with each of the primary rectangular corners (1 15, 125, 135, 145) of the main baffles (1 10, 120, 130,

140) meeting at a central juncture ( 101 ) in the first plane ( 102), and each of the main baffles (1 10, 120, 130, 140) being tilted with respect to the first plane by a tilt angle (1 10.1, 120.1 , 130.1, 140.1) greater than 0° and smaller that 90°.

2. A static mixer (10) according to claim 1 , characterized in that the basic unit comprises at least four, preferably exactly four, main baffles (1 10, 120, 130, 140).

3. A static mixer (10) according to any of claims 1 - 2, characterized in that each of the short parallel sides ( 1 12, 122, 132, 142) of the main baffles ( 1 10, 120, 130, 140) lies in a second plane (103), whereby the second plane (103) being plane parallel to the first plane (102) and offset from the first plane (102).

4. A static mixer (10) according to any of claims 1 - 3, characterized in that tilt angles (1 10.1, 120.1, 130.1 , 140.1) of the main baffles (1 10, 120, 130, 140) are from 20° to 60°, in particular from 30° to 50°.

5. A static mixer (10) according to any of claims 1 - 4, characterized in that at least two of the main baffles (1 10, 120, 130, 140) are of equal size and shape, in particular all of the main baffles (1 10, 120, 130, 140) are of equal size and shape.

6. A static mixer (10) according to any of claims 1 - 5, characterized in that the basic unit (100, 200, 300, 500) comprises two pairs of main baffles being equal in size and shape.

7. A static mixer (10) according to any of claims 1 - 6, characterized in that long parallel sides (1 1 1 , 131) of main baffles (1 10, 130) being diagonally opposed with respect to the central juncture (101) are arranged in parallel to each other.

8. A static mixer (10) according to any of claims 1 - 7, characterized in that main baffles (1 10, 130) being diagonally opposed with respect to the central juncture (101) are of equal size and shape and tilted with respect to the first plane (102) by the same tilt angle.

9. A static mixer (10) according to any of claims 1 - 8, characterized in that obtuse angled corners (1 17, 137) of main baffles (1 10, 130) being diagonally opposed with respect to the central juncture (101) are arranged away form the central juncture (101) and away form each other.

10. A static mixer (10) according to any of claims 1 - 9, characterized in that long parallel sides (1 1 1, 121) of neighbouring main baffles (1 10, 120) are arranged perpendicular to each other.

1 1. A static mixer (50) according to any of claims 1 - 10, characterized in that neighbouring main baffles (510, 520) are of different size and shape and tilted with respect to the first plane by different tilt angles.

12. A static mixer (20, 30) according to any of claims 1 - 1 1 , characterized in that at least one of the main baffles (210, 220, 230, 240) is mitre connected at its oblique side (214, 224, 234, 244) with at least one outer baffle (250, 260, 270, 280), whereby the at least one outer baffle (250, 260, 270, 280) is sticking out of a plane of said at least one main baffle (210, 220, 230, 240).

13. A static mixer (20, 30) according to claim 12, characterized in that each of the main baffles (210, 220, 230, 240) is mitred connected at its oblique side (214, 224, 234, 244) with an individual outer baffle (250, 260, 270, 280).

14. A static mixer (20) according to any of claims 12 - 13, characterized in that the at least one outer baffle (250, 260, 270, 280) is flat and features two straight sides (251, 252, 261 , 262, 271, 272, 281, 282) and a curved side (253, 263, 273, 283).

15. A static mixer (30, 40, 50, 60) according to any of claims 12 - 14, characterized in that the at least one outer baffle (350, 360, 370, 380) is of rectangular trapezoidal shape, featuring a long parallel side (351, 361 , 371 , 381 ) and a short parallel side

(352, 362, 372, 382) being in parallel to each other, a perpendicular side (353, 363, 373, 383) being arranged perpendicular to the short parallel side and the long parallel side, an oblique side (354, 364, 374, 384), a primary rectangular corner (355, 365, 375, 385) at an intersection of the long parallel side (351 , 361 , 371, 381) and the perpendicular side (353, 363, 373, 383), an acute angled corner (317, 327, 337, 347) at the intersection of the long parallel side (351 , 361, 371, 381) and the oblique side (354, 364, 374, 384), and an obtuse angled corner at the intersection of the short parallel side (352, 362, 372, 382) and the oblique side (354, 364, 374, 384).

16. A static mixer (30) according to claim 15, characterized in that the at least one outer baffle (350, 360, 370, 380) is mitred connected at its oblique side (354, 364, 374, 384) with the main baffle (310, 320, 330, 340) mitred connected with said at least one outer baffle (350, 360, 370, 380).

17. A static mixer (30) according to any of claims 12 - 16, characterized in that a length of the oblique side (354, 364, 374, 384) of the at least outer baffle (350, 360, 370, 380) is equal to a length of the oblique side (314, 324, 334, 344) of the main baffle (310, 320, 330, 340) mitred connected with said at least one outer baffle (350, 360,

370, 380).

18. A static mixer (30) according to any of claims 12 - 17, characterized in that the long parallel side (351 , 361 , 371 , 381 ) of the at least one outer baffle (350, 360, 370, 380) lies in the first plane of the basic unit (300) and the short parallel side (352, 362, 372, 382) of the at least one outer baffle (350, 360, 370, 380) lies in the second plane of the basic unit (300) and additionally, the at least one outer baffle (350, 360, 370, 380) is tilted with respect to the first plane by a tilt angle greater than 0° and smaller that 90°.

19. A static mixer (30) according to any of claims 12 - 18, characterized in that the long parallel side (351 , 361 , 371 , 381 ) of the at least one outer baffle (350, 360, 370, 380) is perpendicular to the long parallel side (31 1 , 321 , 331 , 341) of the main baffle mitred (310, 320, 330, 340) being connected with said at least one outer baffle (350, 360, 370, 380).

20. A static mixer (30) according to any of claims 12 - 19, characterized in that the short parallel side (352, 362, 372, 382) of the at least one outer baffle (350, 360,

370, 380) is perpendicular to the short parallel side (312, 322, 332, 342) of the main baffle (310, 320, 330, 340) being mitred connected with said outer baffle (350, 360, 370, 380).

21. A static mixer (30) according to any of claims 12 - 20, characterized in that the basic unit (300) comprises at least two outer baffles (350, 360, 370, 380) which are of equal size and shape.

22. A static mixer (30) according to any of claims 12 - 21, characterized in that the basic unit (300) comprises at least two outer baffles (350, 360, 370, 380) which are equal in size and shape with two of the main baffles (310, 320, 330, 340).

23. A static mixer (30, 40) according to any of claims 12 - 22, characterized in that in a projection on the first plane (302a), the basic unit (300, 300a, 300b, 300c, 30Od) features a swastika like shape and/or a cross like structure with arms bent at right angles.

24. A static mixer (30, 40) according to any of claims 12 - 23, characterized in that the in a projection on the first plane (302a), all of the main baffles and/or all of the outer baffles of the basic unit (300, 300a, 300b, 300c, 30Od) are without any overlap.

25. A static mixer (40) according to any of claims 1 - 24, characterized in that the mixer comprises several basic units (300a, 300b, 300c, 30Od), whereby all of the first planes (302a) of the several basic (300a, 300b, 300c, 30Od) units being coplanar and preferably, all of the basic units (300a, 300b, 300c, 30Od) being of similar structure.

26. A static mixer (40) according to claim 25, characterized in that an obtuse angled corner (337a, 347a) of one of the main baffles (330a, 340a) of the at least one basic unit (300a) is interconnected with an obtuse angled corner (317b, 347b) of one of the main baffles (310b, 340b) of a neighbouring basic unit (300b).

27. A static mixer (40) according to claim 26, characterized in that a primary rectangular corner (365a, 375a) of one of the outer baffles (360a, 370a) of the at least one basic unit (300a) is interconnected with a primary rectangular corner (355b, 385b) of one of the outer baffles (350b, 380b) of the neighbouring basic unit (300b).

28. A static mixer (40) according to any of claims 25 - 27, characterized in that in a projection on the first plane (302a), all of the basic units (300a, 300b, 300c, 30Od) are without any overlap.

29. Duct (41), in particular a gas conducting duct of a power station operated with fossil fuels and/or a flue gas conducting duct of an apparatus for flue gas denitrification (DeNOx) by use of selective catalytic reductions (SCR), comprising a static mixer (40) according to any of the claims 1 - 28, especially with the first plane (302a) of the static mixer (40) oriented perpendicular to a longitudinal direction (42) of the duct (41), preferably with the first plane (302a) oriented downstream and the second plane (303a) oriented upstream.

30. Duct (41) according to claim 29, characterized in that a size and a shape of the static mixer (40) is adapted such that the static mixer (40) covers all of a cross section of the duct (41 ).

31. Use of a static mixer (10, 20, 30, 40, 50, 60) according to any of claims 1 - 28 for mixing a first fluid with a second fluid and/or for mixing a fluid with solid matter.