MIXING DEVICE, METHOD FOR MIXING, AND METHOD FOR CLEANING A MIXING DEVICE

Abstract

The present invention relates to a mixing device (1), especially for mixing solids in a mixing vessel (2), comprising a stirring element (4) having at least two helical stirrer blades (7, 8) connected to a motor-driven shaft (5), wherein the stirrer blades (7, 8) have a first portion (10), a second portion (11) and a third portion (12), every one of these portions (10, 11, 12) has a constant gradient (m1, m2, m3) of one steepness or a gradient (m1, m2, m3) which is different from the constant gradient and has a curvature, and at least one of the constant gradients (m1, m2, m3) has a steepness different from the at least one other constant gradient (m1, m2, m3), or one of the different gradients (m1, m2, m3) has a curvature that is different from the at least one other different gradient (m1, m2, m3).

Claims

1. A mixing device (1) for mixing in a mixing vessel (2), the mixing device having a stirring element (4) which has at least two stirring blades (7, 8) which are of spiral form and which are connected to a motor-driveable shaft (5), wherein the stirring blades (7, 8) each have a first portion (10), a second portion (11) and a third portion (12), wherein each of the portions (10, 11, 12) has a constant gradient (m1, m2, m3) with a steepness or has a non-constant gradient (m1, m2, m3), which deviates from the constant gradient, with a curvature, and wherein at least one of the portions has a first constant gradient (m1, m2, m3) with a steepness which differs from a second constant gradient (m1, m2, m3) of another one of the portions, or at least one of the portions has a first non-constant gradient (m1, m2, m3) with a curvature which differs from the a second non-constant gradient (m1, m2, m3) of another one of the portions.

2. The mixing device (1) as claimed in claim 1, wherein the first constant gradient (m1, m2, m3) has a greater or lesser steepness than the second constant gradient (m1, m2, m3) or wherein the first non-constant gradient (m1, m2, m3) has a greater or lesser curvature than the second non-constant gradient (m1, m2, m3).

3. The mixing device (1) as claimed in claim 1, wherein strippers (13) are arranged at a first end of each of the stirring blades (7, 8), and bottom scrapers (14) are arranged at a second end of each of the stirring blades (7, 8).

4. The mixing device (1) as claimed in claim 1, wherein the mixing vessel (2) has a cylindrically running housing wall (15), a conically running housing wall (16), and a valve (25), wherein the conically running housing wall (16) is arranged between the cylindrically running housing wall (15) and the valve (25).

5. The mixing device (1) as claimed in claim 4, wherein the portions (10, 11, 12) of the stirring blades (7, 8) are arranged parallel to the conically running housing wall (16), and wherein the stirring blades (7, 8) are of the same width in all portions.

6. The mixing device (1) as claimed in claim 4, wherein strippers (13) are arranged at a first end of each of the stirring blades (7, 8), and bottom scrapers (14) are arranged at a second end of each of the stirring blades (7, 8), wherein the strippers (13) are arranged parallel to the cylindrically running housing wall (15) and/or the bottom scrapers (14) have a shape which is adapted to the shape of the valve (25).

7. The mixing device (1) as claimed in claim 1, furthermore having a lid (3) which is mounted onto the mixing vessel (2), wherein at least one flow disrupter (20) which projects into the mixing vessel (2) is arranged on the lid (3), wherein the flow disrupter (20) has a bracket (21) and a baffle plate (22).

8. The mixing device (1) as claimed in claim 7, wherein the bracket (21) has a sensor (28).

9. A method for mixing solids by means of a mixing device (1) as claimed in claim 1, having the, the method comprising the following successive steps: dosing filler substances (A) through at least one first inlet opening (23, 24, 27) into the mixing vessel (2) of the mixing device (1) during a rotation of the stirring element (4), dosing drug substances (B) through the at least one inlet opening (23, 24, 27) and/or a second inlet opening (23, 24, 27) into the mixing vessel (2) of the mixing device (1) during the rotation of the stirring element (4), mixing the filler substances (A) and the drug substances (B) in the mixing vessel, reducing the rotational speed of the stirring element (4) and, in response thereto, conveying a powder mixture composed of the filler substances (A) and the drug substances (B) out of the mixing device (1) through at least one outlet opening (26) of the mixing vessel (2), during which the stirring element (4) continues to rotate at a reduced rotational speed, and wherein the conveying is done pneumatically and/or gravimetrically.

10. A method for cleaning a mixing device (1) as claimed in claim 1, having at least one cleaning nozzle (32) which is arranged on a lid (3) of the mixing device (1) and which is extendable to an inside of the mixing device (1), the method comprising the following successive steps: feeding a cleaning liquid into the mixing vessel (2) with the cleaning nozzle (32), during which the stirring element (4) rotates alternately firstly in a first direction of rotation (D) and then in a second direction of rotation counter to the first direction of rotation (D) at least once, conveying the cleaning liquid, with powder mixture present therein, through at least one outlet opening (26) of the mixing vessel (2), and rinsing the mixing vessel (2) with deionized water.

11. A mixing device (1)for mixing in a mixing vessel (2), the mixing device having a stirring element (4) which has at least two stirring blades (7, 8) which are of spiral form and which are connected to a motor-driveable shaft (5), wherein the stirring blades (7, 8) each have a first portion (10), a second portion (11) and a third portion (12), wherein each of the portions (10, 11, 12) has a constant gradient (m1, m2, m3) with a steepness or has a non-constant gradient (m1, m2, m3), which deviates from the constant gradient, with a curvature, and wherein at least one of the portions has a first constant gradient (m1, m2, m3) with a steepness which differs from a second constant gradient (m1, m2, m3) of another one of the portions.

12. The mixing device (1) as claimed in claim 11, wherein the first constant gradient (m1, m2, m3) has a greater or lesser steepness than the second constant gradient (m1, m2, m3).

13. A mixing device (1)for mixing in a mixing vessel (2), the mixing device having a stirring element (4) which has at least two stirring blades (7, 8) which are of spiral form and which are connected to a motor-driveable shaft (5), wherein the stirring blades (7, 8) each have a first portion (10), a second portion (11) and a third portion (12), wherein each of the portions (10, 11, 12) has a constant gradient (m1, m2, m3) with a steepness or has a non-constant gradient (m1, m2, m3), which deviates from the constant gradient, with a curvature, and wherein at least one of the portions has a first non-constant gradient (m1, m2, m3) with a curvature which differs from the a second non-constant gradient (m1, m2, m3) of another one of the portions.

14. The mixing device (1) as claimed in claim 13, wherein the first non-constant gradient (m1, m2, m3) has a greater or lesser curvature than the second non-constant gradient (m1, m2, m3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Exemplary embodiments of the invention will be described in detail below with reference to the accompanying drawing, in which:

[0056] FIG. 1 shows a schematic section through an embodiment according to the invention;

[0057] FIG. 2 shows a plan view of the embodiment according to the invention from FIG. 1;

[0058] FIG. 3 shows a schematic section through the embodiment according to the invention from FIG. 1 with further components.

DETAILED DESCRIPTION

[0059] FIG. 1 shows a schematic section through a mixing device 1 according to the invention, and FIG. 2 shows a plan view of the mixing device 1 from FIG. 1.

[0060] The mixing device 1 serves preferably for the mixing of solids. Furthermore, the mixing device 1 may also be used for the granulation of solids.

[0061] The mixing device 1 has a mixing vessel 2, a lid 3 mounted onto the mixing vessel 2, and a stirring element 4. The mixing vessel 2, which is formed as one piece, has a housing wall 15, 16, which has a cylindrical housing wall region 15 and, arranged below the latter, a conical or funnel-shaped housing wall region 16. The ratio of the heights of the upper cylindrical housing wall 15 to the lower conical housing wall 16 is preferably greater than 1:2 and preferably in the range 1:3 to 1:4. A diameter of the cylindrical housing wall 15 is preferably greater, at least by a factor of 5, ideally by a factor of 6 to 8, than the diameter of the conical housing wall 16 in the outlet region (outlet opening 26). The mixing vessel 2 has a processing space 18 which, in the plane of the drawing, is delimited to the side by the housing wall 15, 16, upwardly by a removable lid 3, and downwardly by a valve 25 with little dead space.

[0062] The stirring element 4 has a motor-driveable shaft 5, a transverse beam 6 and two stirring blades 7, 8 which are of spiral form. The transverse beam 6 connects the stirring blades 7, 8 to the shaft 5. The stirring blades 7, 8 have the same shape. The stirring blades 7, 8 have a first portion 10, a second portion 11 and a third portion 12. The stirring blades 7, 8 have a constant gradient m1 in the first portion 10, a constant gradient m3 in the third portion 12, and a gradient which deviates from the constant gradients ml, m3, specifically a variable gradient m2, in the interposed second portion 11.

[0063] The gradient m2 of the second portion 11 may follow a mathematical function and has a curvature. The first gradient ml has a greater steepness than the third gradient m3. In other words, the first portion 10 is of steeper or more pronounced form in relation to the third portion 12. Alternatively, the first gradient ml may also have a lesser steepness than the third gradient m3. In other words, the first portion 10 would then be of shallower or less pronounced form in relation to the third portion 12.

[0064] The mixing vessel 2 has the conically running housing wall 16. The first portion 10 is arranged parallel to the conically running housing wall 16. A spacing between the first portion 10 of the respective stirring blade 7, 8 and the conical housing wall 16 amounts to preferably 1 to 10 mm, preferably 5 mm. A width of the stirring blades 7, 8 amounts to approximately 5% of the diameter of the cylindrical housing wall 15 and is constant over the entire length of the stirring blades 7, 8. The conically running housing wall 16 encloses an angle in a range from 25 to 65, in particular of 45, with respect to a horizontal X. The horizontal X is in this case arranged parallel to the inner side/bottom side, the outer side/top side of the lid and to the central axis of the transverse beam 6 of the stirring element 4.

[0065] In each case one stripper 13 is arranged at a first end of the stirring blades 7, 8. A greatest width of the strippers 13 on the side averted from the direction of rotation D is smaller, preferably by a factor of 0.3 to 0.7, preferably of 0.5, than the width of the stirring blades 7, 8. At a second end of the stirring blades 7, 8, there is arranged in each case one bottom scraper 14. The strippers 13 are formed so as to be beveled at an angle at an axially running longitudinal side, wherein the angle is inclined in a range from 20 to 60, in particular of 40.

[0066] Furthermore, the mixing vessel 2 has the cylindrically running housing wall 15. The strippers 13 run parallel to the cylindrically running housing wall 15. The bottom scrapers 14 run, at least in certain portions, parallel to the cylindrically running housing wall 15. Furthermore, the bottom scrapers 14 have a shape which is adapted to the geometry of the valve 25 at the outlet opening 26.

[0067] At least one flow disrupter 20 with a bracket 21 and a baffle plate 22 is arranged on the lid 3. The flow disrupter 20 projects into the mixing vessel 2. The baffle plate 22 is inclined relative to the horizontal X at an angle in a range from 15 to 55, in particular of 35. The baffle plate 22 is inclined at an angle in a range from 15 to 45, in particular of 30, with respect to a straight line 19 running through the axis of rotation R of the shaft 4.

[0068] The mixing device 1 has a first inlet opening 23, a second inlet opening 24 and an outlet opening 26. The first inlet opening 23 and the second inlet opening 24 are arranged on the mixing vessel 2 in the region of the cylindrical housing 15. Filler substances A can be conveyed into the mixing vessel 2 through the first inlet opening 23. Drug substances B can be conveyed into the mixing vessel 2 through the second inlet opening 24. The outlet opening 26 is arranged at the lower end of the valve 25, which has little dead space, of the mixing device 1. The valve 25 which has little dead space may be constructed in accordance with the principle of a ballcock, or of a segmented ballcock. The valve 25 preferably has at least one opening 29 for the introduction of transport air.

[0069] In a method for mixing solids by means of the mixing device 1, the following successive steps are performed: [0070] dosing filler substances A through the first inlet opening 23 into the mixing vessel 2 of the mixing device 1 during a rotation of the stirring element 4, [0071] dosing drug substances B through the second inlet opening 24 into the mixing vessel 2 of the mixing device 1 during the rotation of the stirring element 4, [0072] mixing the filler substances A and the drug substances B, [0073] reducing the rotational speed of the stirring element 4 and, in response thereto, [0074] conveying the powder mixture composed of the filler substances A and the drug substances B out of the mixing device 1 through at least one outlet opening 26 of the mixing vessel 2, wherein the stirring element 4 continues to rotate at a reduced rotational speed, and wherein the conveyance is realized pneumatically and/or gravimetrically.

[0075] The mixing device 1 has a lifting/pivoting device 17 which is connected to the lid 3. An opening and closing of the mixing vessel 2 can be performed by means of the lifting/pivoting device 17.

[0076] FIG. 3 shows the mixing device from FIG. 1 with further components.

[0077] Aside from the first inlet opening 23 and the second inlet opening 24, still further first inlet openings 23 and second inlet openings 24 are provided on the lid 3.

[0078] Optionally or in addition, the mixing device 1 may in each case also have an inlet opening 27 for granulate or pellets. Furthermore, a bidirectionally permeable filter 30 may be provided in the lid 17 of the mixing device 1 or at the connection between inlet opening 27 and dosing means (not shown) in order that displaced air can escape and drawn-in air can flow into the mixing apparatus 1.

[0079] A UV or NIR sensor 28 is arranged on the bracket 21. Furthermore, the mixing device 1 has an inspection glass 31 in the lid 3 for inspections or measurements of quality-relevant measurement variables (for example homogeneity, moisture content, particle size, temperature). On the lid 3, there are arranged two cleaning nozzles 32 which are extendable to the inside of the mixing device 1 and which serve for the feed of cleaning liquid into the mixing vessel 2.

[0080] The mixing device 1 is closed off at its outlet opening 26 by the valve 25, which is configured to reduce dead spaces in the processing space 18, or which is shaped such that the stirring element 4 with its bottom scrapers 14 can perform its mixing action throughout.

[0081] In a method for cleaning the mixing device 1, the following successive steps are performed: [0082] feeding a cleaning liquid into the mixing vessel 2 of the mixing device 1 by means of the cleaning nozzle 32, wherein the stirring element 4 rotates alternately firstly in a first direction of rotation D and then in a second direction of rotation counter to the first direction of rotation D at least once, [0083] conveying the cleaning liquid, with powder mixture present therein, through at least one outlet opening 26 of the mixing vessel 2, and [0084] rinsing with deionized water.

[0085] Subsequent drying of the mixing device 1 may be performed after the described steps. For this purpose, an inlet opening 23, 24 or the opening 27 may be used to convey drying air to the inside of the mixing device 1.