EP2978534B1 - Granules conditioner - Google Patents

Description

The present invention relates to a granule conditioner for optimizing grain sizes of granules.

In particular, in the technical ceramic ceramic granules are required with high flowability. Therefore, the grain sizes should move within a given grain size interval. Both granules with too large grain sizes and too small grain sizes are often not desired.

The most commonly encountered process for producing granules in engineering ceramics is spray drying. For this purpose, fine powders are mixed with liquid to form a suspension. This is then granulated in a spray dryer, i. The suspension is atomized via a nozzle system or centrifugal discs in a hot atmosphere. The resulting droplets are dried in the dryer room by hot air, which is passed in countercurrent to the droplets. The particles contained in the droplets pool together to form granules. The residual moisture and the granule size distribution can be u.a. influenced by the nozzle geometry. The advantage of this method, which has been established for decades, lies in the high granule yield in the range 100-800 μm. The disadvantage lies in the high volume of liquid required for the spraying process, which first has to be fed to the solid and then almost completely dried out again.

An alternative process for the production of granules is the so-called build-up agglomeration. Here, the starting materials are fed as powder particles to a mixer. After the addition of water and possibly organic binders, the mixing movement leads to the formation of agglomerates or granules.

The buildup agglomeration is economically much cheaper, but leads to a poorer particle size distribution, as very quickly form large granules with diameters well above 1000 microns. Therefore, a preparation of the granules must be done.

Are known, for example, from the EP 1 070 543 Granule conditioners, with which the particle sizes of granules can be reduced. These indicate a fixed housing rotatable element with cone-shaped sections on. Between the conical-shaped sections and the stationary housing is a gap which, due to the different cone angles, is conical in cross-section. The granulate particles to be processed are passed through the gap and thereby comminuted. The exit slit is arranged very close to the housing wall.

When using granules for technical ceramics and in particular for granules which were produced by means of buildup agglomeration and therefore usually have a moisture content of between 10 and 15% immediately after preparation, it often occurs in the granulate conditioning, in particular in the ejection zone and on the fixed Housing, to the adherence and re-education of large agglomerates and lumps, which greatly affect the quality of the optimized granules.

Disc mills are also known which use two disks which are rotatable relative to one another and are arranged essentially parallel to one another with a toothing on the upper side, wherein the millbase is brought into a substantially annular gap between the two disks. By the relative rotational movement, generally one of the two discs being fixed, while the other disc is rotating about its disc axis, the material to be ground in the gap is ground by the shear on the teeth. Such disc mills can not be used to condition buildup agglomerates or granules, as the interdental spaces stick together due to the moisture and particles and clog the mill. Typical applications of these mill types are the grinding of dry mineral raw materials, plastics or paper suspensions.

The use of these machines is also for granules for technical ceramics and in particular for granules, which were produced by Aufbauagglomeration and therefore immediately after production usually have a freely movable humidity between 10 and 15%, not possible.

The two discs of the disc mills are arranged within a housing, which generally encloses the discs, for receiving the material emerging from the gap between the two discs due to the centrifugal force. In other words, the starting components are ground by the relative movement of the two discs in the gap formed between the two discs and thrown outwards due to the centrifugal force, so that they hit the wall of the collecting container. If one were to use such a disk mill for the preparation of granules, the granules leaving the grinding disks would adhere to the rigid wall of the housing, as a result This results in that the granules form lumps, so that the quality of the granules leaving the disc mill worsened again. Another granule conditioner for optimizing grain sizes of granules with two rotatable relative to each other, arranged substantially parallel to each other discs according to the preamble of claim 1 is also from the US 2007/029423 A1 known.

Starting from the described prior art, it is therefore an object of the present invention to provide a granule conditioner, with the granules, which have been prepared with a Granuliermischer of fine powders with the addition of a liquid and having a humidity in the range of about 10 to 15% processed can be. According to the invention, this object is achieved by a granulate conditioner which is constructed similar to a disk mill, i. with two relatively rotatable discs arranged substantially parallel to one another, with a granulate inlet through which granules can be brought into the conditioner in an annular gap between the two discs, and a collecting container for receiving the centrifugal force from the gap between the two Slices of leaking granules. However, the collecting container has an elastic curtain, which is at least partially spaced from the collecting container wall and is arranged such that it limits the trajectory of the granules emerging from the gap.

In other words, an elastic material is hung in the collecting container in such a way that the granules emerging from the annular gap due to the centrifugal force strike the elastic curtain. The fact that this has a certain distance from the container wall, he can move accordingly, whereby the probability of adherence of the granules is significantly reduced at the elastic curtain. In principle, the elastic process can be formed from any elastic material, in particular from any polymer material, in particular from any elastomer. Particularly preferably, the elastic curtain is made of polyurethane.

In a preferred embodiment, the elastic curtain is arranged completely surrounding the pair of discs. This has the advantage that granules which emerge essentially over the entire circumference of the disk strike the elastic curtain and from there usually fall into the collecting container without sticking.

It has been shown that the curtain is advantageously bell-shaped. In this case, the curtain connects as possible to the entire circumference of one of the two panes.

The shape of the elastic curtain is formed in a preferred embodiment such that the elastic curtain with an imaginary radial extension of the annular gap an angle between 15 and 75 degrees, preferably between 25 and 65 Degrees and best between 35 and 45 degrees. This has the consequence that the granules emerging from the annular gap impinge on the elastic curtain at substantially the same angle.

It has been shown that a too large impact angle can not prevent adhesion of the granules to the elastic curtain. If the angle of incidence is too small, the receptacle has to be made significantly larger, which increases the costs for the granulate conditioner, without adding any additional benefit.

In a preferred embodiment, the elastic curtain has an S-shaped cross-section, i. a concave portion closer to the gap and an adjoining convex portion. Preferably, an imaginary radial extension of the annular gap intersects the elastic curtain substantially near the connection between the concave region and the convex region.

Furthermore, it has been found that the elastic curtain is substantially smooth at least on the side facing the gap, i. he has no nubs, grooves or ribs. In a further preferred embodiment, both disks are rotatable about their disk axis. It has been found that by this measure, sticking of the possibly moist granules between the panes, i. within the annular gap, is avoided. If both discs rotate, they must be driven at different speeds. The direction of rotation of the rotating discs can be either in the same direction or in opposite directions.

In a preferred embodiment, a disc has a central opening, through which the granules can be supplied. For example, the disk, which has the central opening, can be driven by a hollow shaft, through which the granules can be fed via the central opening into the gap.

For example, the two discs can be aligned horizontally. In this case, the upper disc should have the central opening through which the granules can be fed by gravity into the gap.

In order to adjust the granule size, a device for adjusting the gap width is provided in a preferred embodiment. In a particularly preferred embodiment, the adjustable disc is adjustably mounted on three bearing points, so that in addition to the gap width and the parallelism of the discs to each other by individual adjustment of the support points is adjustable.

Should it nevertheless come to a sticking of the granules in the annular gap, a pivoting device is provided in a preferred embodiment, with the help of a disc, preferably the upper disc, about a pivot axis which is parallel to the gap plane, can be pivoted to access to grant the gap. The adherent material can then be removed and the conditioner is ready for use again.

Furthermore, it is advantageous if the discs are formed at their the gap forming surfaces substantially flat. The fact that the discs have no teeth, the risk of deposits is further reduced.

In a further particularly preferred embodiment, the granulation conditioner is arranged in the same housing as a Granuliermischer. The two elements together form a device for producing an optimized granulate.

• Figur 1 eine schematische Darstellung des Wirkprinzips der Konditioniervorrichtung und
• Figur 2 eine Schnittansicht durch einen Teil eines erfindungsgemäßen Konditionierers.

Further advantages, features and applications of the present invention will become apparent from the following description of a preferred embodiment and the accompanying figures. Show it:

• FIG. 1 a schematic representation of the principle of action of the conditioning and
• FIG. 2 a sectional view through a part of a conditioner according to the invention.

In FIG. 1 is shown schematically the operating principle of the conditioner according to the invention. The conditioner has two rotating disks 1, 2 which are driven to rotate relative to each other. In the example shown, the two discs are rotated in different directions. An annular gap 7 remains between the two disks. The upper disk 2 is driven by means of a hollow shaft 4, through which granules to be optimized can be supplied. The lower disc 1 has a central cone 5 and a row of blades 6 in the center. The granules, which is guided via the hollow shaft 4 due to gravity between the discs is moved radially outwards by the cone 5 and the blades 6, so that it is transported into the annular gap 7 due to the radial acceleration. There, the granules are crushed until it exits the circumference of the annular gap 7 again.

It can be seen that the annular gap 7 has a tapered portion disposed radially further inward, and a portion in which the gap remains substantially constant, which adjoins the tapered portion so as to be radially outward ,

In the conically tapering section, the granules are comminuted, so that the granules can roll in the gap section which adjoins them radially outward with a substantially constant gap width. Alternatively, a plurality of tapered portions could be provided.

In the FIG. 1 Slices shown are usually mounted in a collecting container.

In FIG. 2 an embodiment of the invention is shown. The conditioner is shown here in a sectional view. As far as possible, the same reference numbers as in FIG. 1 used. Again, the granules can be supplied via the hollow shaft 4. The lower disc 1 is driven via the shaft 8, while the upper disc 2 is driven via the hollow shaft 4. Due to the rotating disks, the granules are comminuted in the annular gap 7 and accelerated radially, so that it exits the annular gap 7 at considerable speed on the circumferential side. In the known conditioners, the exiting granules impinges on the housing wall which tightly encloses the ejection gap and is conveyed from there in the direction of the granulate output, for example by means of rotating clearing fingers.

In particular, when the granules have a mean moisture, it may happen that the occurring at high speed from the annular gap 7 granules adheres to the housing wall, so that there accumulations of granules form, which can then uncontrollably detached from the wall , The dissolving pieces consist of adhering granules, which can not be used for further processing.

Therefore, the conditioner according to the invention on an elastic curtain 11, which is arranged such that the emerging from the annular gap 7 granules first meet the elastic curtain 11. The bell-shaped in a preferred embodiment elastic curtain 11 is arranged at a distance from the wall of the collecting container 10 so that it is vibrated upon impact of granules, which causes the probability that granules adhering to the elastic curtain is significantly reduced. Nevertheless, it can not be ruled out here that individual granules can adhere to the curtain. Therefore, the curtain is arranged such that the emerging from the annular gap grains impinge on the elastic curtain 11 substantially with an angle of incidence of about 40 to 50 degrees. This has the advantage that an already adhering to the elastic curtain 11 granular grain is not pressed by the impact of another granular grain against the elastic curtain, but on this by the impact of subsequent particle of granules, which generally causes the adhering to the curtain granules dissolves and falls into the collecting container 9.

In the most preferred embodiment, the elastic curtain is substantially S-shaped in cross-section, i. it has a concave area, a subsequent convex area, wherein the concave area is arranged closer to the annular gap 7. In this case, the curtain 11 is arranged such that the granules leaving the gap strike the curtain substantially in the vicinity of the connection between the concave area and the convex area.

In order to adjust the granule size by changing the gap width of the annular gap 7, one of the rotating disks 1 or 2 is mounted vertically adjustable. The height adjustment of the gap 12 can be done via a support point or over several, preferably three support points, so that in addition to the gap width and the parallelism of the discs is adjustable by individual adjustment of the support points.

The peripheral speed of at least one disk should be more than 10 m / s and preferably more than 20 m / s. When the disks are driven, one disk should have a peripheral speed at least 10% greater than the peripheral speed of the other disk.

LIST OF REFERENCE NUMBERS

1

lower disc

2

upper disc

3

granules

4

hollow shaft

5

cone

6

shovel

7

annular gap

8th

wave

9

receptacle

10

Collecting vessel wall

11

curtain

12

Height adjustment gap

Claims (15)

1. A granular material conditioner for optimising grain sizes of granular materials comprising two discs (1, 2) which are rotatable relative to each other and which are arranged in substantially mutually parallel relationship, a granular material inlet through which granular material can be passed into the conditioner into an annular gap (7) between the two discs, and a catch container (10) for receiving the granular material ejected from the gap between the two discs by virtue of centrifugal force, characterised in that the catch container has an elastic curtain (11), wherein the curtain is spaced at least portion-wise from the catch container wall and limits the trajectory of the granular material issuing from the gap (7).
2. A granular material conditioner according to claim 1 characterised in that the elastic curtain is arranged completely surrounding the pair of discs.
3. A granular material conditioner according to claim 2 characterised in that the curtain is of a bell-shaped configuration.
4. A granular material conditioner according to one of claims 1 to 3 characterised in that the elastic curtain includes an angle of between 15° and 75°, preferably between 25° and 65° and best between 35° and 55° with a notional radial prolongation of the annular gap.
5. A granular material conditioner according to one of claims 1 to 4 characterised in that the elastic curtain has a S-shaped cross-section, that is to say a concave region closer to the gap and a convex region adjoining the concave region, wherein preferably a notional radial extension of the annular gap intersects the elastic curtain substantially in the proximity of the connection between the concave region and the convex region.
6. A granular material conditioner according to one of claims 1 to 5 characterised in that the elastic curtain is substantially flat at the side towards the gap, that is to say it is without knobs, grooves or ribs.
7. A granular material conditioner according to one of claims 1 to 6 characterised in that both discs are rotatable about their disc axis.
8. A granular material conditioner according to one of claims 1 to 7 characterised in that a disc has a central opening, by way of which the granular material can be supplied.
9. A granular material conditioner according to claim 8 characterised in that the disc which has the central opening is drivable with a hollow shaft, through which the granular material can be fed into the gap by way of the central opening.
10. A granular material conditioner according to one of claims 1 to 9 characterised in that there is provided a device for adjusting the gap width, wherein preferably the device is so adapted that the parallelism of the discs relative to each other can be adjusted therewith.
11. A granular material conditioner according to one of claims 1 to 10 characterised in that the two discs are oriented horizontally, wherein preferably there is provided a pivoting device, by means of which a disc, best the upper disc, can be pivoted about a pivot axis which extends parallel to the plane of the gap.
12. A granular material conditioner according to one of claims 1 to 11 characterised in that the annular gap has one or more portions which are conical in cross-section.
13. A granular material conditioner according to one of claims 1 to 12 characterised in that at least one disc is driven at a peripheral speed of more than 10 m/s, preferably more than 20 m/s, wherein preferably when both discs are driven the peripheral speeds of the two discs are different and preferably the peripheral speed of the one disc is at least 10% greater than the peripheral speed of the other disc.
14. A granular material conditioner according to one of claims 1 to 13 characterised in that the discs are substantially flat at their surfaces forming the gap.
15. Apparatus for the production of an optimised granular material comprising a housing in which there are arranged a granulating mixer for producing a granular material from powders and possibly liquid and a granular material conditioner according to one of claims 1 to 14.

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