EP1850080A1 - Mixer with devices for introducing microwaves and method for treating mixtures - Google Patents

Abstract

Mixer (1) comprises devices for injecting microwaves into the inner chamber and arranged so that the microwaves are injected into the lower third of the inner chamber and via a window (3) arranged in a wall (4) of the mixer. An independent claim is also included for a method for treating a mixed material in the mixer.

Description

The invention relates to a mixer with means for feeding microwaves and a method for the treatment of mixed material with microwaves.

From the DE 195 49 494 A1 is a vertical mixer for drying solutions, crystalline substances or solids using microwaves known. The vertical mixer has in the interior a vertically extending shaft, are attached to the mixing tools, A microwave coupler is located above the inner space. The microwaves are fed through the upper end wall, as the mix will not damage the coupling here with minimal likelihood. Also, a coupling through the lower end wall is difficult to accomplish, since drive units are arranged for the mixing tool in the lower area. A disadvantage of the known solution is that there is a relatively high risk that mix is burned or damaged.

A horizontal mixer and drying process is from the EP 1 466 662 A1 known. The horizontal mixer known therefrom comprises mixing tools which are fastened to a horizontally mounted shaft. The horizontally mounted shaft is hollow and has openings on its periphery. A microwave generator is connected to the shaft so that microwaves can be fed into the hollow shaft and these microwaves pass through the openings into the interior of the horizontal mixer and then be able to dry mix. Also in this known solution threaten burns of the mix.

It is an object of the invention to provide a mixer which makes possible an improved treatment of microwaving mix.

The object of the invention is achieved by a device according to claim 1 and a method according to the independent claim. Advantageous embodiments emerge from the subclaims.

To solve the problem, a mixer comprises an interior with mixing tools therein and means for feeding microwaves into the interior. In contrast to the prior art, the means for feeding microwaves are arranged so that the microwaves in the lower half, preferably in the lower Third of the interior of the mixer can be fed.

As a result of gravity, a high mixture density generally prevails in the lower region of a mixer. In contrast to the prior art, microwaves now encounter mixtures in a region where the density of the mixture is high. As a result, the risk of combustion of mix is significantly reduced.

In an advantageous embodiment of the invention, the feeding of microwaves over an end wall of a horizontal mixer, in comparison to a vertical mixer, there is no space problems to feed microwaves in the lower region, The feed via an end wall also allows a planar coupling of microwaves, the is advantageous to avoid combustion of mixed material improved.

In a further advantageous embodiment, the feed via an end wall is such that the location of the feed is remote from the axis, are rotated with the mixing tools and in comparison close to a cylindrical surface of the interior of the mixer. This ensures that the microwave radiation impinges on mixed material where Mixture is mixed very intensively. This further reduces the risk of damage to mix by microwaves.

In a further advantageous embodiment, the coupling for microwaves is in a horizontal mixer from the lowest point looked offset in the direction of rotation of the mixing tools. During operation, mixed material is moved away from the lowest point in the direction of rotation of the mixing tools. Therefore, it is advantageous to provide the coupling of microwaves in a region which is offset from the lowest point in the direction of rotation, under the direction of rotation is the direction to understand that causes mixing of a cylindrical wall by close-coupled mixing tools in Direction axis are promoted.

Microwaves are fed to a mixer by default via a waveguide, the waveguide is preferably wholly or predominantly of a metal, the waveguide is electrically connected at its end to the metal of the mixer. In order to prevent mixing material from getting into the waveguide, a window permeable to microwaves shields the interior of a mixer from the waveguide. The commonly used material, which causes this, consists of Teflon or quartz glass, Although these materials act as a window with respect to microwave rays and shield mix from, However, the risk is then relatively large that the material is not in the long term, the mechanical stresses In order to allow introduction of microwaves at the bottom of a mixer on the one hand, without having to fear on the other hand, that the window through which microwaves get into the mixer, mechanically damaged in the long run, this advantageously consists of a However, zirconium or silicon nitrite are also suitable for achieving improved mechanical stability in comparison with quartz glass or Teflon.

In one embodiment, a measuring unit for microwave radiation is provided, which is arranged along the waveguide for the detection of microwave radiation. Above all, reflected beams are to be measured with this measuring unit. Since it can be assumed that there is no relevant absorption in the waveguide and in the window, the reflected energy gives information about the energy converted in the mix. This is especially true when the mixer is sufficiently filled with mix, a degree of filling of at least 30% is regularly sufficient. Thus, the proper microwave coupling into the mix can be checked and controlled. Because the proportion of reflected microwave radiation informs about the proportion of microwaves that are converted into the mix.

Along the waveguide a pen tuner for optimizing the energy input is advantageously arranged by microwaves.

The mixer is preferably a horizontal ploughshare mixer, this has in its interior a horizontally mounted shaft or axis with attached pflugscharähnlichen mixing tools, Below the shaft are the means for feeding the microwave into the interior of the mixer, in such a mixer is guaranteed in that the mixture below is mixed particularly intensively and evenly. This ensures particularly well that combustion of mixed material is avoided. It is also possible to use so-called Becker paddles in order to achieve particularly good mixing.

The window through which microwaves enter the interior is preferably a more extensive plane-parallel surface, thus providing a relatively large uniformly radiating surface. The specific energy per unit area is relatively low. This ensures further improvement that Mischgutbrbrennungen be avoided.

To solve the problem mixed material is treated by this is mixed in a mixer and microwaves are coupled into the mix there during mixing, where a high density of mix occurs and a coupling of microwaves is avoided where there is a low density of mix is. Combustion of mixed material is thus minimized.

Although microwaves can also be used to dry a mix, this would make little economic sense in the case of surface drying. The method is therefore preferably used for the treatment of mix, wherein the microwave causes a chemical reaction in the mix. For example, B. Material properties of liquid resins can be changed or spices can be pasteurized.

Drying of the mixture using the described microwave radiation is useful, however, if only little energy is brought into the mix via the contact surface in other ways, for example in the case of thermal insulators. Thermal insulators are, for example, ceolite or vermiculite. No thermally insulator in the sense of the invention is glass.

Drying using microwave radiation also makes sense in the case of mixed material with trapped moistures. Especially in combination with drying by generating a vacuum, it is then also possible to dry economically.

• Fig. 1 zeigt einen an einer Stirnseite geöffneten Horizontalmischer 1 , der an einer weiteren Einheit 2 angebracht ist, Die weitere Einheit beinhaltet Einrichtungen für den Betrieb des Mischers 1. Die Einleitung von Mikrowellen erfolgt breitflächig über ein Fenster 3. Das aus Al₂O₃ bestehende Fenster 3 ist im unteren Bereich der Stirnwand 4 angeordnet und zwar gegenüber dem tiefsten Punkt etwas seitlich und nach oben versetzt, Diese Anordnung des Fensters berücksichtigt, dass das Mischgut durch die an einer Welle 12 angebrachten Mischwerkzeuge 5 während des Betriebs vom tiefsten Punkt weg gefördert wird, so dass die größte Dichte des Mischguts während des Betriebs eher in Höhe des Fensters 3 auftritt und zwar in gleicher Weise seitlich versetzt.

The invention will be explained in more detail below by means of an example:

• Fig. 1 shows a horizontal mixer 1 open at one end, which is attached to a further unit 2. The further unit comprises means for operating the mixer 1. The introduction of microwaves is carried out over a wide area via a window 3. The composed of Al ₂ O ₃ window 3 is disposed in the lower region of the end wall 4, namely with respect to the lowest point displaced somewhat to the side and upwards, considered This arrangement of the window that the mixing material through the at a Shaft 12 mounted mixing tools 5 is promoted during operation from the lowest point away, so that the greatest density of the mix during operation rather at the level of the window 3 occurs and in the same way laterally offset.

The introduction of the microwaves via the front side, which is opposite to the other unit 2, space problems are not to be feared. In principle, it is also possible to initiate microwaves through the opposite end, but this can be associated with a greater technical effort, For larger mixers, for example, with a length from 1.50 m (measured from end wall to end wall), microwaves should both Front sides are introduced in order to fully grasp the mix, especially in such a case, an introduction also takes place via the end face, via which the axis of the mixing tool is driven.

The mixer shown in Figure 1 comprises above a tubular access 7. About this u, a, mix can be filled or vacuum generated in the interior to dry, for example, in combination with microwaves mix.

The lateral end wall 4 shown on the right in FIG. 1 can be loosened so as to have a convenient access to the interior. Such access may be useful, for example, for cleaning purposes.

Fig. 2 shows an enlarged means for introducing microwaves through the end face. 4

Shown is right of the pen tuner 6 and although a manually operated version, Following the pen tuner a seal is shown to the left next to it, which suitably consists of Teflon, left next to the seal 8 is an extension 9 shown. This attachment piece 9 serves to attach or fix the window 3 made of Al ₂ O ₃ , alumina is a suitable material both in terms of mechanical requirements and in terms of thermal stability, and alumina is also permeable to microwave radiation.

An existing of elastic material O-ring 10 serves as a seal, the window 3 is held under clamping action, as well as the figure 3 illustrates in more detail. For this purpose, the diameter of the window changes stepwise and is smaller in the direction of the interior of the mixer, correspondingly complementary is provided in the front wall socket 1 1, so it is possible to use the relatively brittle ceramic as a window, without a Bruck to fear the material.

The waveguide opening window 3 is round, since such a cross section is advantageous.

The O-ring seal 10 serves to completely seal the interior of the mixer with respect to the outer space, as illustrated in particular FIG. 3. In FIG. 3, an advantageously inserted intermediate piece 12 is shown, which serves as a calming zone for returning waves, instead of an intermediate piece the extension 9 are made longer accordingly.

Claims (12)

Mixer with an interior, internal mixing tools (5) and means for feeding microwaves into the interior,
characterized in that
the means for feeding microwaves are arranged so that the microwaves are fed in the lower half, preferably in the lower third of the interior, in particular via a in a wall (4) of the mixer befindliches window (3). A mixer according to claim 1, wherein the mixer is a horizontal mixer (1) and the means for feeding microwaves are such that they pass through an end wall of the mixer into the interior, the introduction taking place below the axis (1 2), on which the mixing tools are mounted. Mixer according to claim 1 or 2, wherein the means for feeding microwaves are such that the feed takes place near a cylindrical wall of the interior of the mixer, so that the distance to the cylindrical wall is smaller than the distance to the axis of rotation (12) of the mixing tools (5). Mixer according to one of the preceding claims, in which the microwaves are introduced into the interior of the mixer via a window (3) of ceramic material. Mixer according to one of the two preceding claims, wherein the microwaves are fed via a waveguide to the mixer, with a measuring unit for microwave radiation, which is arranged along the waveguide or in the waveguide for the detection of microwave radiation. Mixer according to one of the preceding claims, wherein the microwaves are fed via a waveguide to the mixer and in which along the waveguide or in the waveguide a Stiftentuner (6) for the optimization of the energy input is arranged by microwaves. Mixer according to one of the preceding claims, wherein the mixer is a horizontal plowshare mixer comprising in its interior a horizontally mounted shaft (12) with mixing tools mounted thereon. Mixer according to one of the preceding claims, wherein the window (3) is designed as a surface radiator. Mixer according to one of the preceding claims, wherein the window (3) is held by clamping action in a wall of the interior of the mixer. Process for the treatment of mixed material by mixing it in a mixer and during mixing microwaves are coupled into the mix where there is a high density of mix and microwaving is avoided, where a low density of mix occurs. Process for the treatment of mixed material according to the preceding claim, in which a chemical reaction in the mix is effected by the microwaves and that preferably material properties of liquid resins are changed or spices are pasteurized or thermal insulators are dried by the microwaves. Process for the treatment of mixed material according to one of the two preceding claims, in which the coupling of microwaves into mixtures is controlled by the measurement of microwaves reflected by the mixture.

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