EP1674150B1 - Static micromixer - Google Patents

Abstract

A static micro-mixer for mixing fluid fractions, in which the openings of the fluid inlets into the mixing chamber are arranged alternately in at least one plane at one end of the chamber, with the outlet(s) at the other end outside the axis of symmetry of the chamber. A static micro-mixer comprising (a) a mixing chamber (12), (b) inlets (5) for at least two fluid fractions to be mixed or dispersed, each with at least one opening (6) into the chamber (12) and (c) at least one outlet (11) from the chamber (12). In this system, (d) the inlet openings (6) for the fluids are arranged in alternating sequence in at least one plane, (e) the chamber (12) is rotationally symmetrical with an axis of symmetry (13), with the outlet(s) at one end and the inlets at the other end, and (f) the outlet(s) is/are outside the axis of symmetry.

Description

The invention relates to a static micromixer with a mixing chamber, feeds for at least two fluid fractions to be mixed or dispersed, each having at least one confluence with the mixing chamber and at least one orifice out of the mixing chamber according to claim 1.

In a micromixer, the fluids to be mixed, each separately separated, are divided into a large number (often several thousand) of fluid flow filaments, all of which open into a mixing chamber via the inlets via the junctions. As a result of the arrangement of the individual microcurrent filaments of the two or more fluid fractions which is closely adjacent to one another, an effective mixing is achieved by a short path and in a very short time. A static micromixer is characterized by the fact that there are no moving parts in it except for the fluid fractions to be mixed.

From the DE 44 16 343 C2 Such a micromixer with at least one mixing chamber and an upstream guide component for the separate supply of fluids to be mixed to a mixing chamber is known, wherein the guide member with dimensions in the millimeter range of several superimposed films is composed with a respective thickness of about 100 microns thick , in which the channels are incorporated as microstructures. The channels of a film comprise feeds for only one of the two fluid fractions.

A similar micromixer, in which the supply channels of two fluids to be mixed or mixed open out in an arcuate manner parallel to one another into the mixing chamber, with otherwise the same design and functional principle DE 195 40 292 C1 described. By this arrangement, one promises a uniform over the entire Ausströmquerschnitt high and fast mixing in the mixing chamber. The guide channels have a constant cross-section with widths less than 250 microns, the films in which the channel structures are incorporated, a thickness of about 100 microns.

Also in the DE 101 23 093 A1 discloses a static micromixer for mixing at least two fluids comprising a plurality of stacked structured films. However, the mixing chamber is formed by a circular breakthrough in a film, wherein the junctions of the two fluids on the same film incorporated in an alternating order in a plane over the entire mixing chamber height over the cylindrical wall of the mixing chamber are arranged. During the mixing, a two-dimensional spiral flow arises in the mixing chamber, which opens into a bore arranged centrally around the axis of symmetry of the mixing chamber on an end face of the mixing chamber (formed by a foil surface delimiting the mixing chamber).

A similar mixing apparatus for mixing at least two fluids with spiral flow guidance is also in the WO 02/089966 A2 described. Here, however, the fluids are additionally mixed in separate mixers in the supply lines before entering the mixing chamber.

However, a spiral flow guide of the aforementioned type is naturally associated with a flow constriction, which significantly limits the possible throughput or causes an increasing flow velocity. In addition, centrifugal forces of the basic flow direction towards the center of the mixing chamber counteract the fluid in the flow spiral. Both influences increase a certain back pressure in the mixing chamber and thus also the probability of turbulent flow components.

Also the US 5,573,334 discloses a static mixer for two fluid fractions, comprising a cylindrical mixing chamber with two end portions, one each per fluid fraction and a common orifice are positioned in each one of the end regions. Also realized here in the orifice by a concentric bore in the bottom of the cylindrical mixing chamber - in principle associated with the aforementioned effects.

On this basis, the object of the invention is to propose a static micromixer of the generic type with an improved mixing efficiency already in the laminar fluid flow, said said obstructing the flow obstructing and limiting disadvantages should be reduced.

This object is solved by the characterizing features in claim 1; the subclaims related thereto contain advantageous embodiments of this solution.

The invention comprises a rotationally symmetrical mixing chamber having an axis of symmetry and two end regions, a number of feeds for at least two fluid fractions to be mixed or dispersed, each having at least one confluence with the mixing chamber and at least one orifice from the mixing chamber. All junctions are located exclusively in one of the two end regions, while the orifices are positioned in the other end region. Preferably, the junctions of the fluid fractions are over the circumference of the shell surface of the mixing chamber, i. not arranged on the end face in alternating order in one or more planes.

An essential feature of the invention relates to the arrangement of the junctions of the fluid fractions in the mixing chamber, in alternating order. The alternating sequence of the junctions and thus of the fluid flow filaments flowing into the mixing chamber thus ensures a high specific mixing surface between the fluid fractions to be mixed or dispersed in the mixing chamber. When arranging the junctions in multiple levels and with an additional offset the junctions in a plane to those in the respective adjacent level, one obtains a far-reaching, as complete as possible sheathing of the fluid flow filaments of a fluid fraction by fluid flow filaments of the other fraction.

An essential feature of the invention comprises a non-concentric arrangement of the orifice in the mixing chamber. Preferably, the orifices are arranged in the outer region of the mixing chamber, preferably the lateral surface. Thus, from the fluid mixture, the above-mentioned possible centrifugal forces which counteract the flow are not to be overcome in height, as expected in the prior art. A dynamic pressure which builds up in rotationally symmetrical mixing chambers according to the prior art and promotes turbulent mixing is also purposefully reduced here. In principle, the dynamic pressure in the invention is also not required, since the mixing in the aforementioned manner in the laminar fluid flow filaments is carried out in a sufficient manner.

Although turbulent flow components fundamentally improve the efficiency of a mixing or dispersion of the fluid flow filaments in the mixing chamber, however, they also cause larger residence time differences of the fluid mixtures in the mixing chamber to be avoided in certain, in particular reactive mixing processes. By avoiding or reducing turbulent flow, the abovementioned residence time differences also advantageously decrease, in particular in comparison with the devices according to the prior art.

If the junctions of a plane are offset from those in the respectively adjacent plane by one opening at a time, embedding of the fluid flow filaments flowing into the mixing chamber into one or more other fluid fractions is obtained. Ideally, each of the fluid flow filaments is completely adjacent, ie on all sides, to fluid flow filaments of another fluid fraction, thus providing the greatest possible mixing surface area between the fluid fractions and as a result a further improvement of the mixing efficiency can be achieved. When mixing or dispersing two fluid fractions is ideally created an arrangement of the individual junction cross-sections similar to a checkerboard arrangement.

The orientation of the junctions to the mixing chamber wall, i. the Einstrählungwinkel the fluid flow filaments between 0 ° (parallel to the mixing chamber wall) and 90 ° (orthogonal to the mixing chamber) preferably in favor of a laminar flow parallel to each other in the direction of the outlet or. Preferably, the junctions for generating a preferred helical fluid guide in the mixing chamber are arranged tangentially, preferably with a small pitch angle to the lateral surface of the mixing chamber serving as a wall.

Constructively, the object is achieved in that the layers are formed by stacked films with grooves as fluid guides, wherein the feeds per fluid fraction via fluid channels, comprising superimposed openings in the films, are fluidly interconnected. The superimposed openings form in the film stack, the fluid channels from which branch off the fluid guides to the mixing chamber. The fluid connections to the fluid channels are preferably placed on the respective limiting outer cover film. Alternatively, a feed can also be realized via channels on one or more foils, the preferably limiting outer cover foils sealingly covering the fluid channels.

The aforementioned low pitch angle of the junctions can be achieved, for example, by designing the foils completely or only in the area of the junctions, ie directly in the wall of the mixing chamber as a truncated cone lateral surfaces. This can be achieved, for example, via cold forming of the individual films or of the film stack prior to the connection of the films to one another with respect to the guide component, for example via diffusion bonding.

It is further appropriate to provide the fluid channels with appropriate means for measurements such as e.g. a thermocouple or for a temperature control or a pressure measurement such. equipped with a heating element or a fluidic heat exchanger and dimensioned accordingly, which can be tailored to the fluid fractions in an advantageous manner immediately before entering the fluid guides individually.

• Fig.1a und b die prinzipielle Seiten- und Draufsicht einer ersten Ausführungsform,
• Fig.2 die perspektivische Ansicht einer zweiten Ausführungsform eines Mikrovermischers,
• Fig.3 eine perspektivische Detailansicht der Einmündungen in die Mischkammer mit zylindrischer Wandung der zweiten Ausführungsform,
• Fig.4 die Aufsichten mehrerer Folien der zweiten Ausführungsform,
• Fig.5 eine Schnittdarstellung einer dritten Ausführungsform mit einem Ringspaltvolumen als Mischkammer,
• Fig.6 eine perspektivische Detailschnittansicht eines Mischkammerabschnitts mit einer fluidischen Temperierungsvorrichtung sowie
• Fig.7 eine perspektivische Schnittdarstellung einer Temperierungsvorrichtung für ein Ringspaltvolumen gemäß der dritten Ausführungsform.

The invention and details thereof are explained in more detail by way of example with reference to embodiments and the following figures. Show it

• 1a and b the basic side and top view of a first embodiment,
• 2 shows the perspective view of a second embodiment of a micromixer,
• 3 is a perspective detail view of the openings in the mixing chamber with a cylindrical wall of the second embodiment,
• 4 shows the plan views of several foils of the second embodiment,
• 5 is a sectional view of a third embodiment with an annular gap volume as a mixing chamber,
• 6 shows a perspective detail sectional view of a mixing chamber section with a fluidic temperature control device and
• 7 is a perspective sectional view of a tempering device for an annular gap volume according to the third embodiment.

The first embodiment acc. 1 schematically shows a micromixer of the first embodiment for the mixing of two fluid fractions A and B with a cylindrical mixing chamber 12 in the mixing chamber housing 14. Also shown is the basic arrangement of the guide member 1 with the leads 5 and junctions 6 at the top and an orifice Feeders and junctions are arranged over the circumferential surface circumference of the one mixing chamber end in a plane, with respect to the fluids A and B in alternating sequence. The guide member 1 is sealingly placed on a mixing chamber housing 14, -glued or -welded. Preferably, the axis of symmetry is orthogonal to the planes formed by the films.

A second embodiment of the static micromixer Figs 2 to 4 again. It differs according to the first embodiment. 1 essentially by the arrangement of the junctions and feeds in several levels. Both embodiments are characterized by a preferably symmetrical about an axis of symmetry 13 preferably cylindrical mixing chamber 12 with two end regions.

Both aforementioned embodiments are basically similar. This structure will be explained in more detail with reference to the second embodiment as follows (see Fig . 2 to 4). The embodiments comprise a guide component 1, preferably consisting of a number of successively gas- and pressure-tight interconnected (eg via a diffusion welding process), alternately stacked films 2 and 3 (first film 2 and second film 3) between serving as a mixing chamber end (mixing chamber) Covering sheet 4 and a mixing chamber housing 14. Each plane is formed by one of the foils 2 or 3, ie the first embodiment comprises only one foil 2 or 3 (not explicitly shown in Fig.1 ). On the films 2 and 3, the feeds 5 and the junctions 6 are incorporated as channel structures (preferably, cutting, erosive or chemically corrosive). The cover films have connection openings 7 for the abovementioned fluid connections which are not shown in FIGS. 1 to 4 . The connection openings adjoin the aforementioned fluid channels in the guide component, which form in the films in the film stack by a number of apertures 8 arranged congruently one above the other. Through these connection openings, the fluids A and B are introduced into the fluid channels (shown in FIG. 2 by arrows on the cover film 4) and from there into the feeders 5 in order to leave the guide component via junctions 6 into the mixing chamber. The surface of the guide member 1 in the region of the junctions 6 forms the flat wall 9 of the mixing chamber.

3 shows detailed views of the films 2 and 3 with the apertures 8, as well as the channel structures, comprising the feeds 5 and the junctions 6 in the region of the wall 9. In this embodiment, only one feed 5 opens out of each opening 8 per film wherein the apertures form the fluid channels for the fluid fractions A and B in an alternating sequence. Each foil thus forms a plane with junctions of the fluid fractions A and B in alternating sequence. On the other hand, the channel structures of film 2 and 3 are not congruent, but have mutually arranged junctions 6 and 5 feeds. If the junctions of the first foils 2 and the second foils 3 are each offset by one junction, the checkerboard pattern of the junctions 6 of the fluids A and B shown in FIG . 3 is obtained, the junctions being oriented at an angle of 90 ° to the wall 9 ( FIG . see Fig.4).

Ideally, the junctions 6 of the fluid fractions A and B are oriented parallel to one another in the mixing chamber in favor of a laminar mixing of the abovementioned fluid flow filaments (see FIG. In principle, angles greater than 0 °, in particular between 45 and 90 °, are suitable.

In contrast, an unequal angle and thus a crossing of the fluid flow filaments are to be striven for in principle, if a targeted adjustment of a turbulent flow state is desired directly at the junctions. The angle difference is preferably above 10 °. If it is above 90 °, there will be a counterflow of the fluid flow filaments and thus again an increased back pressure.

The foils 2 and 3 and thus the junctions (see Figures 2 and 3) and the orifices 11 (see Fig.2) are located in each one of these end portions, wherein the aforementioned guide member 1, the one end of the rotationally symmetric mixing chamber 12 completely encloses. Analogously to the foils 2 and 3 shown in FIG . 2, the feeds 5 shown on the second foil 3 have an offset to the apertures 8, whereby the junctions 6 on the mixing chamber wall 9 with alternating sequence of the foils 2 and 3 and in a order each one confluence per plane (slide) staggered arrangement of the junctions according to a checkerboard pattern (see Fig.3 and 4).

In the illustrated form, the junctions are aligned with respect to the axis of symmetry and each form a right angle with this. Alternatively, the junctions can be arranged askew to the axis of symmetry, whereby in a rotationally symmetrical mixing chamber, a flow direction, preferably a helical, in particular in the outer region of the mixing chamber, pretending. It makes sense to make the mixing chamber as an annular gap volume and / or to arrange the orifices in the flow direction. Preferably, the orifices are arranged outside the axis of symmetry. A possible similar geometric alignment of all junctions in their arrangement to the axis of symmetry for both of the fluid fractions favors a laminar mixing of the fluid flow filaments in the aforementioned manner.

5 shows a sectional view of a further embodiment with annular gap volume as a rotationally symmetrical mixing chamber 12. It differs from the second embodiment illustrated in FIGS. 2 to 4 by the core 15 arranged around the axis of symmetry 13. If the junctions are skewed in the above-mentioned sense to the symmetry axis 13 and also aligned identically with this, the annular gap volume builds around the Core 15 in the direction of the outlet 11 a flow spiral on. 5 also shows, by way of example, the course of the fluid channels 16 formed by the openings of the foils 2 and 3.

FIG. 6 shows the embodiment according to FIG. 5, but with a tempering device in the mixing chamber housing-side mixing chamber wall. In the illustrated embodiment, the temperature device comprises a microfluidic heat exchanger having a microchannel structure and a flowing tempering medium, i. with two ports 1 and two distribution channels 18, between which a plurality of parallel individual channels 19 penetrates the mixing chamber housing 14.

Alternatively, other components of the static micromixer can also be tempered, i. heat or cool, such as in the region of the core, selectively the feeds and Einmündugen for a fluid fraction or the orifice. In particular, with a tempering of the junctions can be undesirable effects of larger temperature and pressure gradients, such as cavitation or changes in the state of matter, reduce upon entry of fluid flow filaments of a fluid fraction from the junctions into the mixing chamber.

Fig. 7 shows a core 15 (see Fig. 5 and 6), which is divided as a double tube in two sub-volumes. In the inner tube 20, the annealing medium is guided axially in one direction to one end of the core in order to return it axially between the inner and outer tubes, with heat being released into the surrounding region of the mixing chamber 12.

LIST OF REFERENCE NUMBERS

1

guiding member

2

first slide

3

second foil

4

cover sheet

5

feed

6

junction

7

port opening

8th

breakthrough

9

wall

11

orifice

12

mixing chamber

13

axis of symmetry

14

Mixing chamber housing

15

core

16

fluid channel

Claims (13)

1. Static micromixer, including

   a) a mixing chamber (12),

   b) inlets (5) for at least two fluid fractions, which are to be mixed or dispersed, each having at least one opening (6) leading into the mixing chamber, as well as

   c) at least one outlet (11) from the mixing chamber,
   wherein

   d) the openings for the fluid fractions are disposed in an alternating sequence in at least one plane,

   e) the mixing chamber has a rotationally symmetrical configuration with an axis of symmetry (13) and two end regions, the outlets and the openings each being positioned in one of the end regions,
   characterised in that

   f) the outlets are disposed outside the axis of symmetry.
2. Static micromixer according to claim 1, characterised in that openings (6) are disposed in at least two planes, the openings of one plane being disposed in an offset manner relative to the openings in the respectively adjacent plane.
3. Static micromixer according to claim 2, characterised in that the openings (6) of one plane are disposed in an offset manner relative to the openings in the respectively adjacent plane by [an amount corresponding to] one respective opening.
4. Static micromixer according to one of the above-mentioned claims, characterised in that all of the openings (6) per fluid fraction are orientated at an angle relative to the wall of the mixing chamber, this angle being between 0° and 90°.
5. Static micromixer according to one of the above-mentioned claims, characterised in that the planes are formed by stacked films (2, 3) having grooves as the fluid guide means, the inlets (5) per fluid fraction being interconnected in a fluidic manner via fluid ducts, including perforations (8), which lie above one another, in the films (2, 3).
6. Static micromixer according to one of the above-mentioned claims, characterised in that the axis of symmetry (13) is orientated orthogonally relative to the planes.
7. Static micromixer according to one of the above-mentioned claims, characterised in that the openings (6) are disposed obliquely relative to the axis of symmetry (13).
8. Static micromixer according to one of the above-mentioned claims, characterised in that the mixing chamber (12) is a ring-gap area.
9. Static micromixer according to one of the above-mentioned claims, characterised in that all of the openings (6) are identically orientated for each fluid fraction in respect of their disposition relative to the axis of symmetry (13).
10. Static micromixer according to one of the above-mentioned claims, characterised in that the openings (6) in the mixing chamber (12) predetermine one direction of flow, and the outlets (11) are identically orientated in respect of their disposition relative to the axis of symmetry (13).
11. Static micromixer according to one of the above-mentioned claims, characterised in that the outlets (11) are orientated in one direction of flow.
12. Static micromixer according to one of the above-mentioned claims, characterised in that the mixing chamber has walls (9) with a temperature control apparatus.
13. Static micromixer according to claim 12, characterised in that the temperature control apparatus includes a microduct structure having a temperature control medium flowing therethrough.

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