Stirrer Apparatus and Method for Mixing

Abstract

A stirrer apparatus, in particular for a usage in crystallizers, comprises a stirrer shaft, with at least one first blade element, which is held at the stirrer shaft and is configured for a mixing of at least one material that is to be mixed, and comprises at least one second blade element, which is held at the stirrer shaft and is configured to keep at least a proximity around the stirrer shaft free from material deposit and/or encrustations,

wherein the stirrer apparatus further comprises at least one stirring blade with a front side and a rear side, which comprises the first blade element and the second blade element.

Claims

1. A stirrer apparatus, in particular for crystallizers, with a stirrer shaft, with at least one first blade element, which is held at the stirrer shaft and is configured for a mixing of at least one material that is to be mixed, and with at least one second blade element, which is held at the stirrer shaft and is configured to keep at least a proximity around the stirrer shaft free from material deposit and/or encrustations by a scraping-off effect, the stirrer apparatus comprising at least one stirring blade with a front side and a rear side, which comprises the first blade element and the second blade element, wherein the proximity around the stirrer shaft is equivalent to a region that is in an operating state over-swept by the stirring blade.

2. The stirrer apparatus according to claim 1, wherein the first blade element and the second blade element form the stirring blade completely.

3. The stirrer apparatus according to claim 1, wherein in the proximity, in a plane (A) that is parallel to the stirrer shaft, the front side intersects with a plane (B), which extends perpendicularly to the stirrer shaft, under an intersection angle of maximally 60°.

4. The stirrer apparatus according to claim 1, wherein the front side and the rear side are oriented at least substantially parallel to one another.

5. The stirrer apparatus according to claim 1, wherein the front side and the rear side converge towards each other.

6. The stirrer apparatus according to claim 1, wherein the stirring blade has a cross-section area that is at least substantially triangle-shaped.

7. The stirrer apparatus according to claim 1, comprising at least one further stirring blade, which is implemented and arranged rotationally symmetrically with respect to the stirring blade.

8. The stirrer apparatus according to claim 1, wherein the stirring blade has a front edge which, starting from the stirrer shaft, is bent rearwards in a radial direction.

9. The stirrer apparatus according to claim 8, wherein the front edge is bent rearwards by at least 90°.

10. The stirrer apparatus according to claim 1, wherein cross-section areas of the stirring blade are at least substantially constant at least over a large portion of a radial extent of the stirring blade.

11. The stirrer apparatus according to claim 1, wherein the stirring blade has an inner radial end and an outer radial end, and is realized tapering toward the two radial ends.

12. A stirring system, in particular a crystallizer, with at least one stirrer apparatus according to claim 1 and with at least one stirring container which the stirrer apparatus is arranged in and which has a bottom surface.

13. The stirring system according to claim 12, wherein the stirring blade has a front edge that extends parallel to the bottom surface.

14. The stirring system according to claim 12, wherein in a view along the stirrer shaft, a region over-swept by the stirring blade in at least one operating state has a diameter that is at least 50% of a diameter of the bottom surface.

15. A method for a mixing, in particular in a crystallization, in particular with a stirrer apparatus according to claim 1 and preferably with a stirring system according to claim 12, to in which, by means of a stirring blade, both a material that is to be mixed is mixed and a proximity around a stirrer blade, which is over-swept by the stirring blade, is kept free from material deposit and/or encrustations by a scraping-off effect.

Description

[0026] Further advantages will become apparent from the following description of the drawings. In the drawings three exemplary embodiments of the invention are illustrated. The drawings, the description and the claims contain a plurality of features in combination. Someone skilled in the art will purposefully also consider the features separately and will find further expedient combinations.

[0027] It is shown in:

[0028] FIG. 1A schematic illustration of a stirring system with a stirrer apparatus and a stirring container,

[0029] FIG. 2 a schematic illustration of the stirrer apparatus, which a stirring blade and a further stirring blade of the stirrer apparatus are fastened on, in an isometric view,

[0030] FIG. 3 a schematic illustration of the stirrer apparatus in a lateral view,

[0031] FIG. 4 a schematic illustration of the stirrer apparatus in a view from above,

[0032] FIG. 5 a schematic illustration of the stirrer apparatus in a further lateral view,

[0033] FIG. 6 a schematic cross-sectional illustration of the stirrer apparatus in the further lateral view,

[0034] FIG. 7 a schematic flow chart of a method for a mixing by means of the stirring system,

[0035] FIG. 8 a further exemplary embodiment of a stirrer apparatus, which a stirring blade and a further stirring blade of the stirrer apparatus are fastened on, in an isometric view,

[0036] FIG. 9 a schematic illustration of the stirrer apparatus of FIG. 8 in a view onto a front side of the hub,

[0037] FIG. 10 a schematic illustration of the hub of the further stirrer apparatus, in a view along a stirrer shaft of the second stirrer apparatus,

[0038] FIG. 11 a schematic illustration of the hub of the further stirrer apparatus, in a view onto an outer radial end of the stirring blade of the hub,

[0039] FIG. 12 a schematic illustration of a hub of a further stirrer apparatus, which a stirrer blade and a further stirrer blade are fastened on, in an oblique view,

[0040] FIG. 13 a schematic illustration of the hub of the further stirrer apparatus, in a view onto a front side of the hub,

[0041] FIG. 14 a schematic illustration of the hub of the further stirrer apparatus, in a view along a stirrer shaft of the further stirrer apparatus, and

[0042] FIG. 15 a schematic illustration of the hub of the further stirrer apparatus, in a view onto an outer radial end of the stirring blade.

[0043] If there are a plurality of objects, in each case only one of such objects is provided with a reference numeral in the figures.

[0044] FIG. 1 shows part of a stirring system 40a. The stirring system 40a is realized as a crystallizer. The stirring system 40a comprises a stirring container 42a. The stirring container 42a is filled with a material that is to be mixed 54a. The stirring container 42a has a bottom surface 44a. Viewed from inside, the bottom surface 44a is realized in a concave manner. The bottom surface 44a is realized in a rotationally symmetrical manner. The stirring system 40a comprises a stirrer apparatus 10a. The stirrer apparatus 10a is arranged in the stirring container 42a. The stirrer apparatus 10a comprises a stirrer shaft 14a. The stirrer shaft 14a is guided through a recess 48a of the bottom surface 44a. The stirrer shaft 14a has an end 46a. The end 46a is oriented counter to a gravity direction 47a. The stirring container 42a comprises a sealing element (not shown), which is arranged in the recess 48a and seals an interstice (not shown) between the stirrer shaft 14a and the bottom surface 44a. The sealing element may, for example, comprise an elastomer and/or a ball bearing.

[0045] The stirrer apparatus 10a comprises a stirring blade 22a, which is fastened on the stirrer shaft 14a. The stirrer apparatus 10a comprises a further stirring blade 32a, which is also fastened on the stirrer shaft 14a. The stirring blade 22a and the further stirring blade 32a are fastened on a hub 12a of the stirrer apparatus 10a. The stirring blade 22a and the further stirring blade 32a are fastened on the hub 12a via a welding process. The further stirring blade 32a is implemented identically to the stirring blade 22a and is fastened on the hub 12a at a 180°-rotation. The hub 12a is slid onto the stirrer shaft 14a and is fastened thereon.

[0046] FIGS. 2 to 6 show different views of portions of the stirrer apparatus.

[0047] The stirring blade 22a comprises the first blade element 16a. The stirring blade 22a comprises the second blade element 18a. The first blade element 16a and the second blade element 18a form the stirring blade 22a completely. The first blade element 16a and the second blade element 18a are respectively implemented identically to the stirring blade 22a. The first blade element 16a and the second blade element 18a are realized by a common subregion, which comprises the entire stirring blade 22a. The first blade element 16a mixes the material that is to be mixed 54a. The second blade element 18a keeps a proximity 20a of the stirrer shaft 14a free from material deposit and encrustations. The stirring blade 22a has a front side 24a. The stirring blade 22a has a rear side 26a.

[0048] The proximity 20a of the stirrer shaft 14a is equivalent to a region over-swept by the stirring blade 22a, which is shown in FIG. 4. In a view along the stirrer shaft 14a, the region over-swept by the stirrer blade 22a has a diameter that is 50% of a diameter of the bottom surface 44a.

[0049] In the proximity 20a, in a plane A that extends parallel to the stirrer shaft 14a, that is shown in FIG. 4 and was used in FIG. 6 as a sectional plane, the front side 24a of the stirring blade 22a intersects with a plane B, which extends perpendicularly to the stirrer shaft B, under an intersection angle 28a of approximately 45° as illustrated in FIG. 6. Alternatively, the intersection angle 28a may have any other value below 60°. The plane A, which extends parallel to the stirrer shaft 14a, intersects with the stirring blade 22a in a cross-section area 30a.

[0050] The front side 24a and the rear side 26a converge towards each other. In the sectional view shown in FIG. 6, an imaginary internal angle 50a between the intersection edges of the front side 24a and the rear side 26a, with an imaginary prolongation of the intersection edges until they meet, is approximately 60°. Alternatively, the internal angle 50a may have any other value below 80°.

[0051] The stirring blade 22a has a cross-section area 30a, which is illustrated in FIG. 6. The cross-section area 30a is essentially triangle-shaped. The cross-section area 30a is realized as a trapezoid. The cross-section area 30a is realized tapering counter to the gravity direction 47a. In a displacement of the intersection plane perpendicularly to the stirrer shaft 14a, cross-section areas of the stirring blade 22a are identical to the cross-section area 30a over a large portion of a radial extent of the stirring blade 22a.

[0052] The stirring blade 22a has an inner radial end 36a, which is shown in detail in FIG. 3. The stirring blade 22a has an outer radial end 38a. The stirring blade 22a is implemented tapering towards the two radial ends 36a, 38a. In a displacement of the sectional plane perpendicularly to the stirrer shaft 14a between the radial ends 36a, 38a, the cross-section areas of the stirring blade 22a are identical to the cross-section area 30a. Toward the outer radial end 38a, the stirring blade 22a ends in a tip 52a.

[0053] The stirring blade 22a comprises a front edge 34a. The front edge 34a extends parallel to the bottom surface 44a, as illustrated in FIG. 1. During a rotation of the stirring blade 22a, the front edge 34a extends always parallel to the bottom surface 44a. The front edge 34a serves for scraping off material deposit and encrustations which accumulate on the bottom surface 44a.

[0054] FIG. 7 shows a schematic flow chart of a method for a mixing, in a crystallization, by way of the stirring system 40a. In the method, by means of the stirring blade 22a, both the material that is to be mixed 54a is mixed and the proximity 20a around the stirrer shaft 14a is kept free from material deposit and encrustations. In a filling step 100a the material that is to be mixed 54a is filled into the stirring container 42a. In a mixing step 110a the stirrer apparatus 10a is brought into the operating state. The mixing step 110a follows the filling step 100a.

[0055] In FIGS. 8 to 15 two further exemplary embodiments of the invention are shown. The following descriptions are limited substantially to the differences between the exemplary embodiments, wherein regarding components, features and functions that remain the same, the description of the exemplary embodiment of FIGS. 1 to 7 may be referred to. In order to distinguish between the exemplary embodiments, the letter a added to the reference numerals of the exemplary embodiment of FIGS. 1 to 7 has been replaced by the letter b in the reference numerals of the exemplary embodiment of FIGS. 8 to 11 and by the letter c in the reference numerals of the exemplary embodiment of FIGS. 12 to 15. Regarding components having the same denomination, in particular regarding components having the same reference numerals, principally the drawings and/or the description of the exemplary embodiment of FIGS. 1 to 7 may be referred to.

[0056] In FIGS. 8 to 11 portions of a stirrer apparatus 10b are shown in different views. A front side 24b and a rear side 26b of a stirring blade 22b of the stirrer apparatus 10b are oriented parallel to each other.

[0057] In FIGS. 12 to 15 portions of a stirrer apparatus 10c are shown in different views. A front side 24c and a rear side 26c of a stirring blade 22c of the stirrer apparatus 10c are oriented parallel to each other. As an alternative, the front side 24c and the rear side 26c could be oriented such that they taper toward each other. The stirring blade 22c may furthermore have an at least substantially triangular cross-section. The stirring blade 22c has a front edge 34c. Starting from a stirrer shaft 14c and in particular from a hub 12c of the stirrer apparatus 10c, the front edge 34c is bent rearwards in a radial direction, in the present case bent rearwards by 90°. Alternatively, the front edge 34c could be bent rearwards by any other angle between 90° and 180°.

REFERENCE NUMERALS

[0058] 10 stirrer apparatus [0059] 12 hub [0060] 14 stirrer shaft [0061] 16 first blade element [0062] 18 second blade element [0063] 20 proximity [0064] 22 stirring blade [0065] 24 front side [0066] 26 rear side [0067] 28 intersection angle [0068] 30 cross-section area [0069] 32 further stirring blade [0070] 34 front edge [0071] 36 inner radial end [0072] 38 outer radial end [0073] 40 stirrer system [0074] 42 stirring container [0075] 44 bottom surface [0076] 46 end [0077] 47 gravity direction [0078] 48 recess [0079] 50 internal angle [0080] 52 tip [0081] 54 material to be mixed [0082] 100 filling step [0083] 110 mixing step