EP0594657A1

EP0594657A1 - Static mixer.

Info

Publication number: EP0594657A1
Application number: EP92913854A
Authority: EP
Inventors: Gerhard Berner; Guenther Proebstle; Wolfgang Herr; Lothar Balling
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1991-07-12
Filing date: 1992-07-02
Publication date: 1994-05-04
Anticipated expiration: 2012-07-02
Also published as: ATE144912T1; JP3174054B2; DK0594657T3; DE59207504D1; CA2113176A1; WO1993000990A1; DE4123161A1; CZ274693A3; CZ284201B6; JPH06509020A; EP0594657B1; US5489153A; CA2113176C

Abstract

L'objet de l'invention est de répartir de manière aussi homogène que possible dans un milieu en écoulement des substances introduites dans un canal d'écoulement, et d'assurer un mélange complet sur un trajet aussi court que possible. A cet effet, on utilise une pluralité d'éléments déflecteurs (12, 38, 56, 57, 78, 79) de dimensions réduites par rapport au diamètre du canal d'écoulement (1, 30, 50, 74). Ces éléments déflecteurs sont disposés en rangées parallèles transversales à l'axe de symétrie (6, 33, 52, 76) du canal d'écoulement. Les éléments déflecteurs de chaque rangée sont inclinés dans une même direction parallèle à la rangée et en sens contraire des éléments déflecteurs des rangées directement adjacentes. L'invention peut être appliquée dans tous mélangeurs statiques de milieux gazeux et liquides.The object of the invention is to distribute the substances introduced into a flow channel as homogeneously as possible in a flowing medium, and to ensure complete mixing over as short a path as possible. For this purpose, a plurality of deflector elements (12, 38, 56, 57, 78, 79) of reduced dimensions are used compared to the diameter of the flow channel (1, 30, 50, 74). These deflector elements are arranged in parallel rows transverse to the axis of symmetry (6, 33, 52, 76) of the flow channel. The deflector elements of each row are inclined in the same direction parallel to the row and in the opposite direction to the deflector elements of the directly adjacent rows. The invention can be applied in all static mixers of gaseous and liquid media.

Description

Static mixer

The invention relates to a static mixer with a plurality of deflection elements arranged in a flow channel

Static mixers are generally installed in pipelines or in other flow channels and serve to distribute substances previously introduced into the pipeline or into the flow channel as homogeneously as possible in the flow medium. For example, it can be used to mix various previously introduced gases. It can also be used to evenly distribute liquid or dusty substances in a gas stream. Static mixers can also be used in liquids.

Known static mixers consist of one or two deflection elements - mostly triangular sheets - which are anchored more or less obliquely in the flow path (see Balke Dürr, special print C56, from VGB Kraftwerkstechnik H8 / 1983, pages 676 to 678). These deflection elements generate violent eddies that downstream it leads to an intensive mixing of the gas flow and all added components, but it is a peculiarity of such static mixers that the complete mixing of the components is only achieved at a sufficiently large distance behind the static mixer or behind the deflection elements Gaseous media about 10 to 20 times the pipe cross-section, which means that there must be sufficient space behind the deflection elements before the subsequent components to which the mixture is to be fed can be connected In industrial plants, however, this space is very limited and not sufficiently available.

A static mixer has also become known in which several small deflection elements are arranged next to one another in a plane perpendicular to the axis of symmetry of the gas channel. With such static mixers, good mixing of the gases or substances previously injected into the gas stream can already be achieved at a relatively short distance from the deflection elements. However, it is a peculiarity of such static mixers with relatively small deflection elements that local concentration differences can be compensated for relatively well and also quickly. Unfortunately, however, large differences in concentration, for example between two opposite sides of the flow channel, can only be compensated for inadequately.

The object of the invention is to develop a static mixer which, with a shortened mixing distance, is able both to equalize large-scale and local concentration differences equally.

This object is solved by the features of claim 1. Further advantageous embodiments of the invention can be found in claims 2 to 12.

Characterized in that, according to the invention, a plurality of deflecting elements which are small in relation to the diameter of the flow channel are used, the deflecting elements are arranged in rows which are parallel to one another and oriented transversely to the axis of symmetry of the flow channel and the deflecting elements of each row in the same direction in the direction parallel to each row and inclined in the opposite direction to the deflection elements of the respectively immediately adjacent rows ensures that both large-scale concentration differences and local concentration differences are equally well balanced. Large-scale concentration differences are reduced by the gas streams running along the rows and crossing the entire flow channel. Local concentration differences, on the other hand, compensate for one another at the boundaries of the opposite flow directions via the edge vortices. Overall, this means that the distance of the gas until the individual components are completely mixed in the flow direction behind the deflection elements is minimized.

In a particularly advantageous embodiment of the invention, the deflection elements can be inclined by about 10 ^* to 45 ^* about axes perpendicular to the direction of the rows and perpendicular to the axis of symmetry of the flow channel. This measure contributes to faster mixing.

In an expedient development of the invention, the rows can extend from one boundary wall to the opposite boundary wall of the flow channel. This promotes a large-scale concentration balance.

A particularly simple construction results if the deflection elements in the embodiment of the invention are fastened on a support grid extending transversely to the axis of symmetry of the gas channel. This construction is relatively simple, stable and space-saving to install.

A particularly intimate mixing is achieved if two in each case in a further development of the invention Adjacent rows of deflection elements are arranged in close proximity to one another in pairs. As a result, the turbulence in the region of these deflection elements is greatly intensified, which is equivalent to a further intensification of the local intimate mixing.

Further details of the invention are explained with reference to four exemplary embodiments shown in the figures. Show it:

1 shows a plan view of a static mixer installed in a rectangular flow channel, FIG. 2 shows a section along line II-II of FIG. 1, FIG. 3 shows a section along line III-III of FIG. 1, FIG. 4 shows a plan view of one in one 5 a section along the line VV of FIG. 4, FIG. 6 a section along the line VI-VI of FIG. 4, FIG. 7 a plan view of a static mixer with increased local turbulence used in a rectangular flow channel, FIG 8 shows a section along the line VIII-VIII of the figure

7, FIG. 9 shows a section along the line IX-IX of FIG. 7, FIG. 10 shows a view of a mixer with diagonal to the

Support grid arranged rows of deflection elements and FIG 11 is a section along the line XI-XI of Figure 10.

FIG. 1 shows a plan view of a static mixer 2 according to the invention installed in a rectangular flow channel, here a gas channel 1. In the illustration in FIG. 1, the direction of view opposite to the direction of flow of the gas stream 4 is selected. This The direction of flow can be seen in the side views, that is to say FIGS. 2 and 3. In the view of FIG. 1, it can also be seen that a support grid 8 is inserted in the gas channel 1, perpendicular to its axis of symmetry 6, which consists of struts 10 which are perpendicular to one another 11, in the exemplary embodiment made of flat steel. Triangular deflection elements 12 made of sheet metal are welded on at the crossing points of the struts 10, 11 of the support grid 8. As shown in the illustrations in FIGS. 2 and 3, these deflection elements 12 are welded onto the outflow side of the support grid 8. It can be seen from FIGS. 1 and 2 that the deflection elements 8 are inclined by approximately 30 ^{* with} respect to the axis of symmetry 6 of the gas channel 1. 1 shows that the deflection elements 12 are arranged in rows on the support grid 8 and the deflection elements of each row 14, 15, 16, 17, 18 are inclined in the same direction in the direction of the row with respect to the main flow direction 4. The deflection elements of the respectively adjacent rows are inclined in the opposite direction, but by the same angle of inclination. It is also noticeable that the deflection elements are much smaller in their dimensions or with their edge length than the dimensions of the gas channel 1. In the exemplary embodiment, the edge lengths of the deflection elements 12 are less than one tenth of the width or length of the gas channel 1.

During operation of the static mixer 2, that is to say when the gas with the components to be mixed flows through the static mixer, as indicated by the arrows 4 in FIGS. 2 and 3, the deflecting elements 12 of each row 14, 15 induce , 16, 17, 18 a transverse flow 22 in the gas channel 1, which extends from one boundary thereof to the opposite boundary. The immediately adjacent rows of Deflection elements 12 produce such a transverse flow 22 from one boundary of the gas channel 1 to the opposite one, but with the flow direction reversed. This achieves a large-scale mass transfer across the entire gas channel 1 at the shortest possible distance. At the same time, the opposite directions of flow of the gas cause ring vortices 20 at their boundaries, which ensure intimate local mixing. The gas flows responsible for the large-area mixing through the gas channel are shown in FIG. 1 with straight arrows 22, the vortices responsible for the local intimate mixing are indicated in FIG. 1 by circular arrows 20.

FIG. 4 shows a top view of another static mixer 32 according to the invention installed in a tubular gas channel 30. Here too, the static mixer comprises a support grid 34, which is installed perpendicular to the axis of symmetry 33 of the gas channel 30 and comprises struts 36, 37 which are perpendicular to one another These struts attach deflectors 38. In contrast to the exemplary embodiment in FIGS. 1 to 3, the transverse struts 36 are welded below the longitudinal struts 37 and the deflecting elements 38 are not welded to the longitudinal struts 37 at the crossing points of the struts of the supporting grid, but in between. Here too, the deflection elements 38 are arranged in rows and the deflection elements of each row are identical to one another and inclined in the opposite direction to the deflection elements of the respectively adjacent row.

When this static mixer 32 is in operation, when the deflection elements 38 are flown against by the gas stream 39, it is similar to the exemplary embodiment in FIGS 3 through each row of equally inclined deflection elements 38, a transverse flow directed across the gas channel and crossing the entire gas channel 30 is generated, which is exactly opposite to the respectively adjacent transverse flow. Compare the straight arrows 40 in FIG. 4.

As the circular arrows 42 show, local small vortices are formed between each two adjacent cross currents 40, which ensure intimate local mixing. The arrangement of the deflection elements between the crossing points of the struts 36, 37 is somewhat simpler in terms of production technology than that according to the exemplary embodiment according to FIGS. 1 to 3. With regard to the mixing function, there is no significant difference between the two variations. Both static mixers 2, 32 can also be installed in a rectangular gas channel 1 and vice versa instead of in a tubular gas channel 30.

FIG. 7 shows a plan view of another static mixer 54 according to the invention installed in a rectangular gas channel 50 perpendicular to its axis of symmetry 52. Here too, the deflection elements 56, 57 are fastened on a support grid 58 made of struts 60 oriented perpendicular to one another. Here too, the deflection elements 56, 57 are arranged in rows, wherein the deflection elements of one and the same row are all inclined transversely to the gas flow 62 and the deflection elements 56, 57 of the respectively adjacent row are all inclined in the opposite direction to the gas flow.

Deviating from the exemplary embodiment according to FIGS. 1 to 6, however, the deflection elements 56, 57 of two adjacent rows are moved close together and at the same time somewhat in the deflection direction of the gas stream 62 shifted against each other. The inclination of two closely spaced deflection elements 56, 57 of adjacent rows are directed away from each other. The arrangement can best be seen with the aid of FIGS. 7, 8 and 9.

When this static mixer 54 is in operation, the gases to be mixed flow through the support grid 58 with the deflection elements 56, 57 in the illustration in FIG. 7 from below the plane of the drawing and become these

Gas flow 62 in the area of the deflection elements 56, 57, i.e. in the area of the grid crossing points, on both sides of the same in the opposite direction deflected transversely to the gas flow 62. Compare the straight arrows 68. Because the deflection elements on both sides of the crossing points of the support grid 58 are inclined away from one another, part of the crossflow reaches the suction region of the respectively directly adjacent deflection element. This causes an intensive swirling between these two deflection elements, which is expressed in a spiral vortex 64 above the deflection elements. This spiral vortex can be clearly seen in FIGS. 8 and 9. For the rest, analogous to the exemplary embodiments in FIGS. 1 and 4, further rotary vortices 66 arise between the opposite transverse flows 68 at the boundary thereof.

While there are no significant differences with respect to the large-scale mixing of the gas flow compared to the two exemplary embodiments according to FIGS. 1 and 4, there is a strong intensification in the exemplary embodiment according to FIG. 7 with regard to local mixing. This intensification of the local mixing by producing many small, very intensive ones Spiral vortex 64 manifests itself in a very slight increase in the flow resistance of this static mixer 54. In return, however, here is the run-on section, behind which one can speak of complete mixing of the gas flow, compared to the first two

Embodiments have been shortened a little further.

FIG. 10 shows a top view, FIG. 11 shows a modification of the static mixer 54 of FIG. 7 in side view. Here too, a flat support grid 70 made of struts 72 oriented perpendicular to one another is arranged in a rectangular gas channel 74 perpendicular to its axis of symmetry 76 . Here, too, the same deflection elements 78, 79 as in FIG. 7 are arranged in rows and two deflection elements 78, 79 of immediately adjacent rows are pressed close together and inclined in the opposite direction to the primary gas flow 75. However, the pairs of deflection elements 78, 79 fastened along the same struts 72 are each arranged in mirror image, so that non-mirror image pairs of deflection elements can only be found in rows diagonally to the support grid 70.

When this static mixer 80 is in operation, the gases to be mixed flow through the support grid 70 with the pairs of deflection elements 78, 79 in the illustration in FIG. 10 from below the plane of the drawing upwards. The opposite deflection of the gas flow 75 at the deflection elements 78, 79 of each pair creates a spiral vortex 82 above these pairs. These spiral vortexes are indicated in FIG. 10 by the circular arrows 84. Because these spiral vortices have a mirror-inverted sense of rotation at adjacent supporting grid positions, they induce cross currents 86 which run diagonally to the supporting grid and which are indicated by straight arrows 88 are indicated. In comparison with the other three exemplary embodiments, the intensity of the local mixing has been further increased in this static mixer 80 at the expense of the large-scale mixing. This static mixer 80 is therefore particularly suitable for intensive mixing of substances which are already mixed to a certain extent evenly in the inflowing gas stream.

These static mixers shown here can also be used in liquid media. In this case, however, the inclination of the deflection elements with respect to the basic flow will be somewhat reduced. In the case of both liquid and gaseous media, it is advantageous to gradually increase the inclination of the deflection elements from their base surface on which they are attached to the supporting frame to their head ends, that is to say to curve the deflection elements within themselves. This enables the cross currents to be increased.

The static mixers disclosed can be used not only in process engineering for uniform mixing of different material flows, that is to say gases, liquids and / or solids transported therein. With such static mixers, even more uniform mixing of different reactants in the chemical industry can be carried out over relatively short distances. For example, the denitrification of flue gases in power plants and in waste incineration can be favorably influenced by mixing the reducing agent - usually the NH, - with the flue gas very evenly.

Claims

1. Static mixer (2, 32, 54, 80) with a plurality of deflection elements arranged in a flow duct, characterized in that a plurality of deflection elements (12, 38, 56) that are small in relation to the diameter of the flow duct (1, 30, 50, 74) , 57, 78, 79) are used, the deflection elements are arranged in mutually parallel rows oriented transversely to the axis of symmetry (6, 33, 52, 76) of the flow channel, and the deflection elements of each row are in the same direction in the direction parallel to the row and in opposite directions the deflection elements of the immediately adjacent rows are inclined.

2. Static mixer according to claim 1, characterized in that the deflection elements (12, 38, 56, 57, 78, 79) about axes perpendicular to the direction of the rows and perpendicular to the axis of symmetry (6, 33, 52, 76) of the flow channel (1 , 30, 50, 76) are inclined by approx. 10 ^* to 45 ^* .

3. Static mixer according to claim 1 or 2, so that the rows extend from the one boundary wall to the opposite boundary wall of the flow channel (1, 30, 50, 74).

4. Static mixer according to one of claims 1 to 3, d a d u r c h g e k e n n z e i c h n e t that the

Deflection elements (12, 38, 56, 57, 78, 79) are fastened on a support grid (8, 34, 58, 70) extending transversely to the axis of symmetry (6, 33, 52, 76) of the gas channel.

5. Static mixer according to one of claims 1 to 4, d a d u r c h g e k e n n z e i c h n e t that two immediately adjacent rows of Auslenk¬ elements (56, 57, 78, 79) are arranged in pairs close to each other.

6. Static mixer according to one of claims 1 to 5, d a d u r c h g e k e n n z e i c h n e t that the immediately adjacent deflection elements (56, 57, 78, 79) of the rows arranged closely next to each other are displaced relative to each other in the direction of deflection.

7. Static mixer according to one of claims 1 to 6, d a d u r c h g e k e n n z e i c h n e t that the deflection elements are one-dimensionally curved.

8. Static mixer according to one of claims 1 to 7, d a d u r c h g e k e n n z e i c h n e t that the deflection elements (12) on the crossing points of the support grid (8) are attached.

9. Static mixer according to one of claims 1 to 7, d a d u r c h g e k e n n z e i c h n e t that the deflection elements (38, 56, 57, 78, 79) on the struts (37) between the crossing points of the support grid (34, 58, 70) are attached.

10. Static mixer according to one of claims 1 to 9, characterized in that the edge length of the deflection elements (12, 38, 56, 57, 78, 79) is less than one fifth of the mean diameter of the flow channel (1, 30, 50, 74) are.

11. Static mixer according to one of claims 1 to 9, characterized in that the edge length of the deflecting elements (12, 38, 56, 57, 78, 79) is less than one tenth of the mean diameter of the flow channel (1, 30, 50).

12. Static mixer according to one of claims 1 to 11, d a d u r c h g e k e n n z e i c h n e t that the rows of deflecting elements inclined in the same direction (78, 79) are aligned diagonally to the support grid.