EP2529829B1 - Dispersal rotor for homogenising flowable media - Google Patents

Description

The invention relates to a dispersing rotor for homogenizing flowable media, which has an axially pointing rotor toothing.

Homogenizers are used, inter alia, in the pharmaceutical, cosmetic, chemical and food industries for the production of creams, ointments, pastes, mayonnaises and similar products. Usually, a homogenizer is arranged at the bottom of a mixing container, which is usually designed as a rotor-stator dispersing machine. Such a homogenizer is for example in EP 0 988 887 A1 disclosed. Other generic devices are in WO02 / 060569 and DE-A-19537303 described.

The invention has for its object to provide a way to homogenize flowable media that is simple, efficient and versatile.

A dispersing rotor according to the invention has a rotor toothing, which forms a labyrinth toothing for medium emerging in the radial direction from the direction of the rotor axis to the outside.

First, some terms used in the invention are explained. The dispersing rotor according to the invention is used for dispersing (homogenizing, emulsifying or suspending) flowable media. This includes that too Preparation of single or multi-phase mixtures such as gels, emulsions or suspensions. The dispersing rotor has an axially pointing rotor toothing. The term gearing refers to openings in a circumferential wall of the rotor through which medium or mixture passes during operation in the radial direction to the outside. Such a toothing may have individual openings in an otherwise closed, circumferentially extending wall. In general, however, the toothing is formed by a arranged on a peripheral portion of the rotor plurality of axially extending teeth having baffles for the medium to be mixed. The terms axial and radial are related in the context of the present invention to the axis of rotation of the rotor. According to the invention, the rotor toothing forms a labyrinth toothing for medium passing outward in the radial direction from the direction of the rotor axis. The term labyrinth toothing means that mixed material fed in the region of the axis of the rotor can not escape through the toothing on a straight line pointing in the radial direction, but that due to the arrangement of the teeth it always has to change direction, ie has to flow through a labyrinth path.

The invention has recognized that, surprisingly, a good mixing and homogenizing effect can be achieved exclusively by means of such a rotor, without this having to cooperate with a rotor toothing (which is generally fixed) relative to the rotor. The labyrinth toothing according to the invention allows good mixing and homogenization exclusively by using such a dispersing rotor.

According to the invention, the homogenization of the medium is much gentler than when using a rotor-stator dispersing machine of the prior art, since a lower energy input and thus also a lower heat development takes place. Accordingly, the mechanical energy to be expended for homogenization is correspondingly lower. The reduced heat input allows a gentler homogenization of sensitive products such as gels or creams.

The invention has thus recognized that the large shearing of the medium on alternating rotor and stator teeth considered necessary in the prior art is not required, instead the constant rate changes in the labyrinth path permit elongation and comminution of liquid droplets (for example, emulsions) and thus a homogenization. When passing through a row of teeth, the medium receives a pulse through the rotating rotor which, depending on the speed and flow direction of the medium and the rotational speed of the rotor, leads to a corresponding change in the direction of flow and velocity of the medium.

The dispersing rotor according to the invention preferably has so-called rows of teeth. It is a row of teeth to a arranged on a circumferential circle arrangement of teeth, which thus each have the same radial distance from the rotor axis.

Preferably, the dispersing rotor is formed closed at one or both axial ends. This means that in the closed area formed no or at most a slight leakage of medium in the axial direction is possible. Preferably, not the entire circular area of the Rotor formed closed at both axial ends, but at least at one axial end is a central opening through which medium can enter from one axial side. Preferably, at least at one axial end (end face), only that circular ring is formed closed, which is occupied by the rotor toothing. It is thus ensured that the medium passing through penetrates the dispersing rotor radially from the inside to the outside on the intended labyrinth paths.

The axial height of the rotor toothing may be 10 to 30 mm, more preferably 12 to 25 mm. The term refers to the free height in the ring plane of the corresponding rotor toothing, through the passage of medium is possible. The diameter of a dispersing rotor according to the invention can be adapted to the installation conditions. For example, when installed in pipelines, small diameters of, for example, 5 to 10 cm may be used. When installed in larger mixing vessels, the diameter can be, for example, between 10 and 30 cm. The stated values can be combined as desired to upper and lower limits according to the invention.

Preferably, the teeth of the rotor toothing in the radial direction between them gaps of 0.3 to 3 mm, preferably 0.5 to 1.5 mm. Preferably, this is the clear radial distance between each two concentrically arranged rows of teeth.

In the circumferential direction, the teeth (preferably the teeth of each of the concentric rows of teeth) preferably have gaps of 0.5 to 4 mm, more preferably 1 to 3 mm, more preferably 1.5 to 2.5 mm.

The coverage of a row of teeth over the circumference of this row of teeth is preferably between 40 and 80%, more preferably 50 and 70%. These limits can be combined as desired to areas according to the invention. The term overlap refers to that portion of the circumference of a row of teeth on which the passage of medium in the radial direction is blocked by this row of teeth. For example, a coverage of 60% means that 60% of the circumference of the corresponding row of teeth is blocked by the teeth while the remaining 40% of the circumference allows medium to pass through.

In a particularly preferred embodiment of the invention, two rows of teeth arranged adjacent in the radial direction together have complete coverage. This means that medium can not pass through these two radially successive rows of teeth, without departing from the radial direction. A straight line in the radial direction, which passes in one of the two rows of teeth through a gap between two teeth, thus meets in the other of these two rows of teeth on a tooth. This complete overlap of two adjacently arranged in the radial direction rows of teeth caused by the increased directional change of the medium improved homogenization.

According to the invention, preferably at least a part of the teeth has conveying surfaces pointing in the circumferential direction, which are designed to impart a pulse component radially outwards to the impacting medium. "Pointing in the circumferential direction" does not mean that these surfaces are aligned exactly in the circumferential direction, that is a perpendicular to these surfaces exactly in the circumferential direction. It deals Rather, as a rule, be inclined surfaces, a perpendicular to these inclined surfaces preferably has a direction component radially outward. If, when the dispersing rotor rotates, this conveying surface encounters passing medium, an impulse is exerted on the medium which has a directional component radially outward. Accordingly, the medium is accelerated radially outward with an acceleration or velocity component.

The invention furthermore relates to a homogenizing device for homogenizing flowable media which has a dispersing rotor according to the invention. The omission of a stator toothing offers a number of significant advantages. It is a relatively free positioning of the dispersing within the homogenizer possible because no structural precautions must be taken to vorzuhalten a engaging in the rotor teeth stator toothing. According to the invention, the dispersing rotor can be arranged, for example, in a lower region of a homogenizing container, preferably in its bottom region. It is also possible to arrange a plurality of dispersing rotors within a container, for example to arrange a plurality of such rotors on an axis guided through the lid or bottom of such a container. It is also possible within the scope of the invention to arrange the dispersing rotor in a pipeline through which the medium to be mixed is passed. The dispersing rotor according to the invention can thus be used for so-called in-line mixing in a pipeline.

By dispensing with a stator toothing, it is possible to install the dispersing rotor according to the invention with comparatively larger tolerances in a homogenizing vessel, as in the prior art, where a precise interaction with a stator toothing is required. This allows in particular the use of drives in which the rotor is usually mounted with larger tolerances, such as non-contact drives such as magnetic drives. Non-contact drives have the advantage that no penetrations of drive axles through the wall of the homogenizing container are required and thus containers and dispersing rotor can be designed so that the possibilities of cleaning and germ free are optimized.

Fig. 1:

schematisch einen teilweisen Axialschnitt durch einen erfindungsgemäßen Dispergierrotor;

Fig. 2:

schematisch einen Schnitt in der Radialebene durch eine erfindungsgemäße Rotorverzahnung;

Fig. 3-7:

schematisch unterschiedliche Einbausituationen eines erfindungsgemäßen Dispergierrotors in einer Homogenisiervorrichtung;

Fig. 8:

schematisch weitere mögliche Ausgestaltungen bei Labyrinthverzahnung.

Embodiments of the invention will be described below with reference to the drawings. Show it:

Fig. 1:

schematically a partial axial section through a dispersing rotor according to the invention;

Fig. 2:

schematically a section in the radial plane through a rotor toothing according to the invention;

Fig. 3-7:

schematically different installation situations of a dispersing rotor according to the invention in a homogenizer;

Fig. 8:

schematically further possible embodiments of labyrinth teeth.

The dispersing rotor according to the invention has a receptacle 1 for a drive shaft (in FIG Fig. 1 not shown). Rotationally connected thereto is a rotor 2, on which pump vanes 4 are arranged, which serve to convey medium entering through the inlet 3 radially outward. The order the pump blade 4 corresponds for example to the arrangement shown in FIG EP 0 988 887 A1 , there pumping 18 in Fig. 2 ,

In a radially outer ring arranged the dispersing rotor according to the invention has four radially staggered rows of teeth 5, is conveyed through the medium entering the inlet 3 radially outward. These rows of teeth form a labyrinth path for radially outward medium, that is, medium can not pass without directional changes through these rows of teeth. In the area of the toothing 5, the dispersing rotor is closed towards the axial end faces, so that mixed material from the toothing can not escape axially upwards or downwards.

In the embodiment of Fig. 1 Six radially staggered rows of teeth are arranged. Fig. 2 schematically shows a radial section through these rows of teeth. It can be seen radially staggered rows of teeth, each having teeth 6. It concerns with Fig. 2 an enlarged view. The length of the column in the circumferential direction (reference numeral 7) is about 2 mm, the gap width in the radial direction (reference numeral 8) about 0.5 mm. It can be seen that the teeth 6 form a labyrinth path through which medium must pass outwards. When the rotor is rotated in the circumferential direction 15, the circumferentially extending surfaces 16 of the teeth form conveying surfaces which when impinged on medium impart a radially outward pulse component thereto.

The diameter of the in Fig. 1 shown dispersing rotor may be about 10 cm in this embodiment. Typical rotational speeds during operation may, for example be 6500 to 14,000 min ^-1.

Fig. 3 schematically shows a mounting situation in which a dispersing rotor according to the invention is arranged in a mixing container above the container bottom 9. A drive shaft 10 passes through the container bottom.

Fig. 4 shows another variant of a homogenizer according to the invention, in which a longer drive shaft 10 passes through the container bottom 9 passes. At this drive shaft 10 two or more if required, more dispersing rotors according to the invention are arranged.

In the embodiment of the Fig. 5 If a dispersing rotor according to the invention is installed in the bottom housing of a mixing container. A cover 17 covers the rotor at its outer periphery and forms, together with the bottom housing, an annular gap 11 through which medium emerging on the outer circumference of the rotor can be guided back into the container. Alternatively, it is possible to use this medium through a in Fig. 5 remove circulation line, not shown, from the container and supply, for example, in another (preferably upper) region of the container again.

Fig. 6 shows an embodiment in which the rotor is driven via a magnetic coupling. Outside the container wall 9, a drive shaft 13 is arranged, which is provided with magnets and within the container arranged magnets 12 entrains, which are rotatably connected to the rotor.

Fig. 7 shows an embodiment in which a drive shaft 15 is guided by the lid 14 of a mixing container.

Fig. 8 schematically shows further possible embodiments of a labyrinth toothing according to the invention. At 16, a toothing is indicated, in which the individual teeth have a rod shape, that are circular in cross section. At 17, a toothing is shown, which is formed of checkerboard-like teeth with a square cross-section. In section 18 an irregular labyrinth toothing is shown. Here it is preferable to ensure that over the entire circumference of the rotor results in a uniform mass distribution and it does not come to an imbalance. At 19 schematically an irregular labyrinth toothing is shown, in which the individual teeth have a different shape from the basic geometric shapes in cross-section. It is understood that sections 16-19 are not present in a single dispersing rotor according to the invention, but schematically show four possible configurations of the labyrinth toothing of a rotor.

Claims (13)

1. Dispersing rotor for homogenising free-flowing media, said dispersing rotor having an axially oriented rotor toothing formation, characterised in that the rotor toothing formation forms a labyrinth toothing formation for medium passing radially outward from the direction of the rotor axis.
2. Dispersing rotor according to claim 1, characterised in that it has at least 2, preferably 2 to 16, more preferably 2 to 8, more preferably 4 to 8 radially spaced-apart rows (5) of teeth.
3. Dispersing rotor according to either claim 1 or claim 2, characterised in that it is closed at one or both axial ends.
4. Dispersing rotor according to any of claims 1 to 3, characterised in that the axial height of the rotor toothing formation is 10 to 30 mm, preferably 12 to 25 mm.
5. Dispersing rotor according to any of claims 1 to 4, characterised in that the teeth (6) of the rotor toothing formation have radially directed gaps of 0.3 to 3 mm, preferably 0.5 to 1.5 mm.
6. Dispersing rotor according to any of claims 1 to 5, characterised in that the teeth (6) or rows of teeth of the rotor toothing formation have circumferentially directed gaps of 0.5 to 4 mm, preferably 1 to 3 mm, more preferably 1.5 to 2.5 mm.
7. Dispersing rotor according to any of claims 1 to 6, characterised in that the coverage of a row of teeth over the circumference of this row of teeth is 40 to 80%, preferably 50 to 70%.
8. Dispersing rotor according to any of claims 1 to 7, characterised in that two radially adjacent rows of teeth together provide full coverage.
9. Dispersing rotor according to any of claims 1 to 8, characterised in that at least some of the teeth have circumferentially oriented delivery surfaces (16) that are designed to subject medium that comes into contact therewith to an impulse component in the radially outward direction.
10. Homogenisation apparatus for homogenising free-flowing media, characterised in that it has a dispersing rotor according to any of claims 1 to 9, the homogenisation apparatus not having a stator toothing formation engaging in the rotor toothing formation.
11. Homogenisation apparatus according to claim 10, characterised in that the dispersing rotor is arranged in a lower region, preferably a base region, of a homogenisation tank.
12. Homogenisation apparatus according to claim 10, characterised in that the dispersing rotor is arranged in a medium-channelling conduit.
13. Homogenisation apparatus according to any of claims 10 to 12, characterised in that the dispersing rotor has a contactless drive, preferably a magnetic drive.

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