EP0967004A1 - Static mixer - Google Patents

Abstract

A static mixer has an outer housing (1) and an inner enclosure (2) with a process inlet and outlet (7; 8), containing two or more layers of parallel, wavy corrugated or zig-zagged cross members (3;4;13;14) arranged alternately to intersect. The layer are preferably perpendicularly to each other, and with the peaks and troughs of alternate layers joined together e.g. by welding. The cross members can be formed with internal flow channels (5; 6) for a heat transfer fluid.

Description

The invention relates to a static mixing device for mixing viscous Fluids consisting of an inner housing with a mix inlet and a mix outlet is constructed, the two or more layers of mutually parallel wide or zigzag-shaped webs, which preferably at an angle α from 90 ° to each other are alternately arranged one above the other, and at their upper and lower vertices are connected. In particular are provide the webs for the passage of a heat transfer fluid with channels, so that the mixer can also serve as a heat exchanger.

For mixing liquids, static mixers are often used as internals in Pipelines used. A pump pushes the liquids to be mixed a pipe provided with such internals.

The following two devices may be mentioned as examples of static mixers.

Mischen beim Herstellen und Verarbeiten von Kunststoffen", Herausgeber: VDI-Ges. Kunststofftechnik, VDI-Verlag Düsseldorf, 1986, S. 238-241) wird die Fluidströmung durch ein im Rohr eingebautes Trennblech geteilt. Dieses ist um die Rohrachse tordiert. In jedem der Teilströme der Flüssigkeit entsteht eine wirbelförmige Strömung, die zur Umverteilung der Flüssigkeit im Querschnitt führt. Mehrere solcher Mischelemente sind in der Praxis hintereinander angeordnet, um die Flüssigkeit immer wieder neu zu teilen und eine gute Mischwirkung zu erreichen. Die Druckstabilität dieser Mischer gegenüber hochviskosen Fluiden ist vergleichsweise gering.With the so-called Kenics mixers (cf.

Mixing in the manufacture and processing of plastics ", publisher: VDI-Ges. Kunststofftechnik, VDI-Verlag Düsseldorf, 1986, pp. 238-241), the fluid flow is divided by a partition plate installed in the pipe. This is twisted around the pipe axis. In each The partial flows of the liquid form a vortex-shaped flow, which leads to the redistribution of the liquid in cross-section. In practice, several such mixing elements are arranged one behind the other in order to divide the liquid again and again and achieve a good mixing effect is comparatively small.

The so-called SMX mixers (cf. US 4,062,524) consist of two to one another vertical grids of parallel sheet metal strips, which at their crossing points are welded together. The manufacturing cost of this mixer is because of the many welded connections relatively high.

The heat exchange of highly viscous liquids when they pass through known ones Heat exchangers typically take place at a very low Reynolds number. If, for example, smooth pipes are used for heat exchange, one is against Zero Reynolds number the heat exchange rate low and on the part of the heat exchanger essentially only depends on the pipe length used. A a significant improvement in heat exchange is then possible through a Combination of the tube heat exchanger with a static mixing device.

This combination is known in two forms. For one, in the Tubes of a tube bundle heat exchanger static mixing elements are used. The above-mentioned mixer elements from Kenics are used here in particular. Secondly, the tubes can be used as elements of a static mixer be used. This is for example in the German patent DB 28 39 564 C2.

The use of a tube bundle heat exchanger through which the product flows does not apply but in many chemical processes. If e.g. a polymerization reaction must be cooled, then it is agitated in a pipe with a slower flow the higher residence time of the reactants achieves a higher degree of polymerization. This may make the liquid in the pipe more viscous than in neighboring pipes. In the As a result, the flow rate of the mix is further slowed down. With certain Process parameters can therefore block the pipe with polymer.

In such processes is a static mixer formed from heat exchanger tubes as preferred in DE 28 39 564 C2. The manufacturing cost of these mixers is, however so high that this solution is often rejected as uneconomical.

The object of the invention is to find a static mixer that has a good the known static mixer shows comparable mixing effect, which may is coolable or heatable and which can be produced in a simple manner and therefore inexpensively is.

According to the invention, this object is achieved by a static mixing device for mixing viscous fluids, built up at least from an inner housing with a mix inlet and a mix outlet that are two or more Encloses layers of parallel, wavy or zigzag-shaped webs, alternating at an angle α, preferably rotated from each other by 90 ° are arranged one above the other, and at their upper and lower vertices are connected to one another, and optionally an outer casing.

In its more symmetrical preferred embodiment, the webs are static Mixer connected by joints so that from each joint except four web elements that span a tetrahedron the joints that are on the edge of the static mixer. In In this version, the structure of the web insert is reminiscent of the topology of a Diamond grid. As a web insert, the entirety of the interconnected Layers of bars of the mixer understood.

In a preferred variant of the static mixing device, the webs are selected Layers or all layers for the passage of a heat transfer fluid Channels. The webs are e.g. executed hollow and the cavities serve then as channels for the heat transfer medium.

In a particularly preferred embodiment, the webs are in the direction of flow of the product so wide that the heat transfer channels mentioned each along a straight line from one side of the mixer to the opposite Are guided through the webs.

This further simplifies the production of such a mixing device, because e.g. side slides used in the injection molding of the mixer model can be used to form the channels in the webs.

A variant of the static mixing device that is particularly easy to produce is characterized in that the device is stacked in two or more is divided into separate segments, each containing two, three or more Layers, in particular three layers of webs are joined together. The segments can be made individually by casting and then in any number and Combination can be joined together, if necessary also with different Geometry of individual segments.

In a preferred form of the invention, the webs overlap directly one above the other Layers of webs at their junctions, especially through interlocking recesses at the apex of the webs.

Another preferred variant of the mixing device is characterized in that that the parallel webs a layer of webs to the center distance adjacent Bars of the next but one layer of bars located above or below are laterally offset.

To further improve the mixing effect, especially in the case of highly viscous Fluids are the layers of webs opposite the main flow direction of the Mixed material from the mixed material inlet to the mixed material outlet is smaller by an angle β or greater than 90 °.

In particular, the mixer is constructed in such a way that the lattice planes that form the connection points the webs form a ply so that none form an angle of 90 ° with the main flow direction through the mixer. Hereby it is avoided that the flow into non-mixing flow cells (Partial flows) decays.

The mixer can be easily manufactured by master molding. Hereby the desired low manufacturing effort is achievable, reducing the cost of the mixer can be kept low. E.g. can the web insert of the Mixer made of wax can first be injection molded as a model. The wax model then serves as a lost model in the investment casting, e.g. from the wax model a ceramic hollow mold is produced. The one cast from metal in the hollow form The web insert can then simply be inserted into a housing and fastened.

The above mixer variant consisting of segments is even easier to do manufacture, since the inner housing is created together with the webs during investment casting.

In the case of a mixer with heat exchanger channels, the channels can still go into the housing wall be welded in. This can be done in the manufacture of shell and tube heat exchangers usually used welding machines become.

The invention is explained in more detail below with reference to the figures, without this restricting the invention in detail.

Fig. 1a

die vereinfachte schematische Vorderansicht auf einen erfindungsgemäßen heiz-/kühlbaren statischen Mischer mit Außengehäuse 1, Mischguteinlaß 7 und Mischgutauslaß 8.

Fig. 1b

die Draufsicht zu dem Mischer aus Figur 1a.

Fig. 2

eine isometrische Ansicht des statischen Mischer aus Figur 1a bzw. 1b, wobei ein Teil des Außengehäuses 1 und der Produkteinlaßstutzen 7 nicht dargestellt sind.

Fig. 3a

in der Vorderansicht die obersten Lagen von Stegen 3, 13 und 4, 14 des Mischers nach Figur 1a.

Fig. 3b

die Draufsicht zu Figur 3a.

Fig. 3c

eine isometrische Ansicht zu Figur 3a

Fig. 4

ein Mischersegment 41 mit drei übereinander angeordneten Lagen von Stegen 43, 44 und 47

Fig. 5a

den Aufbau eines Stegeinsatzes für einen anderen Mischer, der durch Gießen gefertigt werden kann

Fig. 5b

die Draufsicht aufden Stegeinsatz von Figur 5a

Fig. 5c

eine isometrische Ansicht zu Figur 5a

Fig. 6

den Stegeinsatz einer Variante des Mischers nach Fig. 1a mit seitlicher Versetzung der Stege in übereinander liegenden Steglagen

Fig. 7

den Stegeinsatz einer Variante des Mischers nach Fig. 1a mit schräg zur Hauptströmungsrichtung verlaufenden Stegen in übereinander liegenden Steglagen

Fig. 8a

die Seitenansicht auf einen erfindungsgemäßen statischen Mischer ohne Heizkanäle. Das Gehäuse ist nicht dargestellt

Fig. 8b

den Mischer aus Figur 8a in der Draufsicht

Fig. 8c

den Mischer aus Figur 8c in einer perspektivischen Ansicht

Fig. 9

den Stegeinsatz nach Fig. 3c mit getrennten Stegen.

Show it:

Fig. 1a

the simplified schematic front view of a heatable / coolable static mixer according to the invention with outer housing 1, mixture inlet 7 and outlet 8.

Fig. 1b

the top view of the mixer of Figure 1a.

Fig. 2

an isometric view of the static mixer of Figure 1a or 1b, a part of the outer housing 1 and the product inlet port 7 are not shown.

Fig. 3a

in the front view the uppermost layers of webs 3, 13 and 4, 14 of the mixer according to Figure 1a.

Fig. 3b

the top view of Figure 3a.

Fig. 3c

an isometric view of Figure 3a

Fig. 4

a mixer segment 41 with three layers of webs 43, 44 and 47 arranged one above the other

Fig. 5a

the construction of a web insert for another mixer that can be manufactured by casting

Fig. 5b

the top view of the web insert of Figure 5a

Fig. 5c

an isometric view of Figure 5a

Fig. 6

the web insert of a variant of the mixer according to FIG. 1a with lateral displacement of the webs in superimposed web positions

Fig. 7

the web insert of a variant of the mixer according to FIG. 1a with webs running obliquely to the main flow direction in web layers lying one above the other

Fig. 8a

the side view of a static mixer according to the invention without heating channels. The housing is not shown

Fig. 8b

the mixer of Figure 8a in plan view

Fig. 8c

the mixer of Figure 8c in a perspective view

Fig. 9

the web insert according to Fig. 3c with separate webs.

Examples example 1

An embodiment of the static mixer according to the invention is shown in FIG side view. The mixer insert and the inner housing of the mixer are one outer housing (casing 1) surround and has an inlet 7 and one Outlet 8 for the mix

The mixer is also equipped with feed lines 9 and 11 for a heat carrier oil Leads 10 and 12 provided for the heat transfer oil. 1b is the top view drawn on the mix inlet 7 through which the internals of the mixer can be seen are.

In the isometric view according to FIG. 2, one can see how the inner housing 2 also the riser insert 3, 4 is inserted into the casing 1.

To illustrate the structure of the mixer in Fig. 3a is a front view of the Mixer shown with omission of the inner housing 2 and casing 1.

The webs 3, 13 and 4, 14 are kept so wide in the flow direction that straight Cooling channels 6, 16 can pass through them.

3b shows a schematic plan view of the web insert of the mixer according to FIG. 1a without housing 2 and casing 1 from the side of the mixture inlet 7. From this the sequence of the first four layers of webs becomes clear. The top one Layer is formed by webs 3, the second layer by webs 4, the third layer through the webs 13 followed by the fourth position of the webs 14. The mix flow is divided at the edges 19 and led to the valleys 20 of the webs. Deeper Layers of webs point to valleys 20 'at which the mix flows out laterally.

3c shows the sequence of the interconnected layers of FIG Bridges. In this embodiment, the zigzag webs 3, 13 and 4, 14 their edges, which face another layer, recesses 21, 22 (see Fig. 9) so that they engage in directly adjacent webs so that a nested composite of webs is formed, which is rigid.

Example 2

A segment 41 of a static mixer is shown in FIG. 4, which has three layers of webs 43, 44 and 47.

The webs 43 of a layer are arranged parallel to one another. The one below the other lying rows of webs 43 and 44 are each arranged perpendicular to each other. All webs 43, 44, 47 are crossed by straight channels 45, 46, 48, through which a heat transfer fluid can flow and in the wall of an inner housing 42 flow out. Several of the segments 41 may optionally not be shown Seals joined together give a pack that fits into one (not shown) coat to be fitted. The segment is easy using metal casting to manufacture.

Example 3

5a to 5c, a variant of the web insert according to FIG. 3a is shown can be manufactured using casting technology and as an insert in an inner housing 2 serves according to FIG. 2.

In contrast to FIG. 3a, the edges of adjacent webs 53, 54 or 54, 55 meet with straight surfaces on top of each other, but have no nested recesses on The heat transfer channels 56 are straight and are by means of Do not produce slides for the archetype. The gaps 58 can be between the webs 57, 55 by means of slides in the manufacture of the preform produce.

The zigzag webs 53 and 54 are at the connection points 17 and 18 each connected to the webs 54, 55 of the underlying layer of webs. The individual segments of the webs 53 and 54 or 54 and 55 tense a connecting point 17 or 18 each have a tetrahedron.

Example 4

Flow cells may still occur in the mixer according to Example 1, that are not mixed. To avoid this, the symmetry in Broken with respect to the flow direction. This is possible in which the Lattice planes are sheared with respect to the direction of flow. The order 6 shows that this is due to uneven lateral offset the next but one Layers of webs 63, 65 and 64, 67 is possible.

Example 5

Another way to break symmetry is to shift the lattice planes perpendicular to the direction of flow.

In Fig. 7 a web insert is shown in which the webs 73 a layer of webs so are arranged so that their vertices form a plane which is at an angle of about 85 ° to the main flow direction.

The upper vertices of each individual web 73, 74, 75, 77 are each around seen about 5 ° rising from the heat transfer inlet side (left or rear in Fig. 7) arranged. This will also make training more preferred To prevent flow cells.

Example 6

FIGS. 8a to 8c show a variant of the web insert with FIGS. 5a to c, whose webs (83, 84, 85, 86) have no heating channels.

The top layer of bars (83) and the bottom layer of bars (87) are partial interrupted.

Claims (7)

Static mixing device for mixing viscous fluids at least from an inner housing (2) with a mixture inlet (7) and a mixture outlet (8), the two or more layers of each other encloses parallel, wavy or zigzag-shaped webs (3, 4, 13, 14), which are rotated at an angle α, preferably 90 ° to each other are arranged alternately one above the other, and at their upper or lower Vertices (17; 18) are connected to one another, and if necessary an outer casing (1). Device according to claim 1, characterized in that the webs (3, 13) or (4, 14) selected layers or all layers to pass one Heat transfer fluids are provided with channels (6, 16; 5 15). Device according to one of claims 1 or 2, characterized in that the Device in two or more separate segments stacked one on top of the other (41) is divided, in each of which two, three or more layers of webs (43, 44) are joined together. Device according to claim 3, characterized in that the segments have three layers of webs (43, 44, 47). Device according to one of claims 1 to 3, characterized in that the webs (3, 13; 4, 14; 43, 44, 47) of layers lying directly one above the other of webs overlap at their junctures, especially by interlocking Recesses (21; 22) at their apex. Device according to one of claims 1 to 4, characterized in that the parallel webs (3; 4) of a layer of webs to the center distance adjacent Webs (13; 14) of the next but one or the next Position of webs are laterally offset. Device according to one of claims 1 to 5, characterized in that the positions of webs (3, 13; 4, 14; 43, 44) opposite the main flow direction the mix from the mix inlet (7) to the mix outlet (8) an angle β is made smaller or larger than 90 °.

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