STIRRING DEVICE

Abstract

A radially conveying stirring device with at least one stirring element hub configured to rotate about a rotational axis, with at least one stirring blade and with at least one carrier arm connecting the stirring blade to the stirring element hub, wherein there is at least one half-line which starts from the rotational axis, goes through a center of mass of a connecting surface area of the carrier arm to the stirring element hub and is free from intersection points with the stirring blade, and wherein the stirring blade features at least one beveling dividing the stirring blade into at least two stirring blade sections, wherein the carrier arm is embodied at least substantially L-shaped, wherein the beveling is arranged at least substantially in parallel to the rotational axis.

Claims

1. A radially conveying stirring device with at least one stirring element hub configured to rotate about a rotational axis, with at least one stirring blade and with at least one carrier arm connecting the stirring blade to the stirring element hub, wherein there is at least one half-line which starts from the rotational axis, goes through a center of mass of a connecting surface area of the carrier arm to the stirring element hub and is free from intersection points with the stirring blade, and wherein the stirring blade features at least one beveling dividing the stirring blade into at least two stirring blade sections, wherein the carrier arm is embodied at least substantially L-shaped, wherein the beveling is arranged at least substantially in parallel to the rotational axis.

2. The radially conveying stirring device according to claim 1, wherein, viewed in a direction of the rotational axis, a main extension direction of the stirring blade includes an angle with the half-line that is between 45 and 135.

3. (canceled)

4. The radially conveying stirring device according to claim 1, wherein the carrier arm is arranged at least substantially at mid-level of the stirring blade.

5. (canceled)

6. The radially conveying stirring device according to claim 1, wherein a main extension length of the stirring blade sections decreases from a stirring blade inner edge of the stirring blade towards a stirring blade outer edge of the stirring blade.

7. The radially conveying stirring device according to claim 1, wherein a blade height of the stirring blade decreases towards a stirring blade outer edge of the stirring blade.

8. The radially conveying stirring device according to claim 1, wherein, in a proximity of a stirring blade inner edge of the stirring blade, a blade height of the stirring blade is equivalent to a value between 1% and 30% of an entire stirring element diameter.

9. The radially conveying stirring device according to claim 1, wherein, in a proximity of a stirring blade outer edge of the stirring blade, a blade height of the stirring blade is equivalent to a value between 0.5% and 15% of an entire stirring element diameter.

10. The radially conveying stirring device according to claim 1, wherein the stirring element hub, the carrier arm and the stirring blade are embodied at least partly in a one-part implementation with each other.

11. A radial stirring element with a radially conveying stirring device according to claim 1.

12. A stirring system with at least one container and with at least two radial stirring elements according to claim 11, which are arranged in the container.

13. A method for operating a stirring system according to claim 12, wherein a middle-to-highly viscous medium arranged in a container is mixed in such a way that an axial flow is at least substantially suppressed.

14. The method for operating a stirring system, according to claim 13, wherein a plug flow is generated in the container.

Description

DRAWINGS

[0030] Further advantages will become apparent from the following description of the drawings. In the drawings an exemplary embodiment of the invention is shown. 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.

[0031] It is shown in:

[0032] FIG. 1 a stirring element embodied as a radial stirrer, with a stirring device, in a perspective presentation,

[0033] FIG. 2 the stirring element when viewed in a direction of a rotational axis,

[0034] FIG. 3 the stirring element in a lateral view, and

[0035] FIG. 4 a stirring system with a container and with a plurality of stirring elements according to FIGS. 1 to 3.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0036] FIGS. 1 to 3 show a stirring element 32 embodied as a radial stirrer, in a fully mounted state in a perspective view (cf. FIG. 1), in a plan view (cf. FIG. 2) and in a lateral view (cf. FIG. 3). The stirring element 32 is in the present case embodied in a one-part implementation. Alternatively it is conceivable to implement a stirring element in a multi-part implementation, e.g. by means of at least one screw connection. The stirring element 32 comprises a stirring device, in particular a radially conveying stirring device. The stirring device is configured for mixing highly viscous media. In the present case the stirring device is configured for a disintegration of biomass and in particular for a usage in the production of ethanol.

[0037] The stirring device comprises a stirring element hub 10. The stirring element hub 10 is in the present case embodied in a one-part implementation. The stirring element hub 10 is completely made of stainless steel. Alternatively however it is also conceivable to implement a stirring element hub in a multi-part implementation. In that case the stirring element hub could be embodied, for example, in a two-part and/or four-part implementation, preferably with identical stirring element hub components. The stirring element hub 10 is configured to accommodate, in at least one operating state, a stirring shaft 36 (cf. in particular FIG. 4). The stirring element hub 10 is configured to be fixated to the stirring shaft 36. An orientation of the stirring shaft 36 defines a rotational axis 12 of the stirring device. The stirring element hub 10 is herein configured to rotate about the rotational axis 12. The stirring element hub 10 is in the present case configured for rotating about the rotational axis 12 in both directions.

[0038] The stirring device further comprises a plurality of stirring blades 14. In the present case the stirring device comprises two stirring blades 14. For the sake of better overview, in FIGS. 1 to 3 only one of the stirring blades has been given reference numerals. The stirring blades 14 are embodied at least substantially identical to one another. The stirring blades 14 are embodied at least substantially plate-shaped. The stirring blades 14 have an at least substantially constant material thickness. The stirring blades 14 are embodied in one-part implementations. The stirring blades 14 are completely made of stainless steel. Viewed perpendicularly to a main extension plane of the respective stirring blade 14, the stirring blades 14 are embodied at least substantially trapezoid-shaped (cf. in particular FIG. 3). The stirring blades 14 each comprise a stirring blade inner edge 28 and a stirring blade outer edge 30. Furthermore the stirring blades 14 are arranged at approximately 180 angular distances with respect to each other. Alternatively a stirring device may also comprise three stirring blades which are arranged in particular at 120 angular distances with respect to each other, and/or four stirring blades which are arranged in particular at 90 angular distances with respect to each other. Alternatively it is also conceivable that a stirring device comprises more than four stirring blades, e.g. at least five, at least six, at least eight and/or at least ten stirring blades. The stirring blades 14 are arranged spaced apart from the stirring element hub 10. In a mounted state, the stirring blades 14 are arranged on the stirring element hub 10 in such a way that the main extension plane of the respective stirring blade 14 and the rotational axis 12 are oriented at least substantially in parallel to one another. In the present case the stirring blades 14 are fixated to the stirring element hub 10 indirectly.

[0039] For this purpose the stirring device comprises a plurality of carrier arms 16. In the present case the stirring device comprises two carrier arms 16. Each carrier arm 16 is allocated to one of the stirring blades 14. For the sake of overview, in FIGS. 1 to 3 only one of the carrier arms 16 is given reference numerals. The carrier arms 16 are embodied at least substantially identically to each other. The carrier arms 16 are respectively embodied in a one-part implementation. The carrier arms 16 are completely made of stainless steel. The carrier arms 16 are each embodied as a rod-shaped bar. The carrier arms 16 are implemented at least substantially cylinder-shaped, in particular circle-cylinder-shaped. In the present case the carrier arms 16 are implemented at least substantially L-shaped, viewed perpendicularly to the rotational axis 12.

[0040] The carrier arms 16 are configured to connect the stirring blades 14 to the stirring element hub 10. For this purpose the carrier arms 16 are fixated, on the one hand, to the stirring element hub 10 and, on the other hand, to one of the stirring blades 14. In the present case the carrier arms 16 are embodied in a one-part implementation with the stirring element hub 10. A contact surface between the respective carrier arm 16 and the stirring element hub 10 corresponds to a connecting surface area 20 of the carrier arm 16 to the stirring element hub 10. An angle between the carrier arms 16 and the rotational axis 12 is in the present case equivalent to 90. Alternatively it is however also conceivable that at least one carrier arm 16 includes an angle with a rotational axis that differs from 90. The carrier arms 16 are furthermore embodied in a one-part implementation with the respective stirring blade 14. The carrier arms 16 are arranged at mid-level of the respective stirring blade 14, in particular centrally on a respective stirring blade 14. The carrier arms 16 run, at least to a large extent, in parallel to a main extension direction 38 of the respective stirring blade 14. The carrier arms 16 run, at least to a large extent, along a main extension length of the stirring blade 14. A material thickness of the carrier arms 16 and/or a diameter of the carrier arms 16 is herein at least substantially constant. Alternatively it is conceivable that a material thickness of carrier arms and/or a diameter of the carrier arms decreases towards a stirring blade outer edge. Moreover any further kinds of fixation, deemed expedient by someone skilled in the art, are also conceivable. It is in particular conceivable that in a mounted state at least one carrier arm is connected to a stirring blade and/or to a stirring element hub at least partly and/or completely by a force-fit and/or form-fit connection, e.g. in particular via a screw connection and/or a plug connection. It is further conceivable to implement a stirring element hub, at least one carrier arm and/or at least one stirring blade of a different material that is deemed expedient by someone skilled in the art, e.g. stainless steel.

[0041] In the following only one exemplary embodiment of one of the stirring blades 14 and the carrier arm 16 allocated to said stirring blade 14 will be described, wherein the description below may be applied to the other stirring blade, which is in particular embodied at least substantially identically, and to the other carrier arm, which is in particular embodied at least substantially identically.

[0042] In the present case there exists a half-line 18, which starts from the rotational axis 12, goes through a center of mass of the connecting surface area 20 of the carrier arm 16 and is free from intersection points with the stirring blade 14. Furthermore the main extension direction 38 of the stirring blade 14 includes an angle of approximately 105 with the half-line 18.

[0043] The stirring blade 14 further comprises a beveling 22. The beveling 22 is arranged in parallel to the rotational axis 12. The beveling 22 is arranged on a side of the stirring blade 14 that faces towards the stirring blade outer edge 30. A bevel angle of the beveling 22 is approximately 150. The beveling 22 divides the stirring blade 14 into two stirring blade sections 24, 26. A main extension length of the stirring blade sections 24, 26 decreases from the stirring blade inner edge 28 towards the stirring blade outer edge 30. An inner stirring blade section 24 of the stirring blade sections 24, 26 has a main extension length of approximately 29% of an entire stirring element diameter. An outer stirring blade section 26 of the stirring blade sections 24, 26 has a main extension length of approximately 10% of an entire stirring element diameter. Alternatively it is conceivable that a stirring blade comprises a plurality of bevelings, e.g. at least two and/or at least three bevelings.

[0044] Beyond this a blade height of the stirring blade 14, in particular an extension of the stirring blade 14 towards the rotational axis 12, decreases towards the stirring blade outer edge 30. In an inner region of the stirring blade 14, the blade height of the stirring blade 14 is constant. In a middle region of the stirring blade 14, the blade height of the stirring blade 14 changes linearly. In an outer region of the stirring blade 14, the blade height of the stirring blade 14 changes linearly. In the present case a gradient of a change in the blade height of the stirring blade 14 in the middle region is at least substantially equivalent to a gradient of a change in the blade height of the stirring blade 14 in the outer region. A blade height of the stirring blade 14 in a proximity area of the stirring blade inner edge 28 is in the present case approximately equivalent to 8% of an entire stirring element diameter. Furthermore a blade height of the stirring blade 14 in a proximity of the stirring blade outer edge 30 is approximately equivalent to 2% of an entire stirring element diameter. Alternatively it is conceivable that a blade height of a stirring blade changes linearly over an entire longitudinal extension of the stirring blade.

[0045] FIG. 4 shows an exemplary stirring system, which is in particular continuously operated and continuously flowed through, with a vertically arranged container 34 and with a plurality of stirring elements 32 arranged in the container 34. In the present case at least two stirring elements 32 are arranged in the container 34. The stirring elements 32 are embodied at least substantially identically to each other. The stirring elements 32 correspond to the stirring element 32 of FIGS. 1 to 3. Each of the stirring elements 32 thus comprises a stirring device according to the invention. The stirring elements 32 are embodied as multi-step stirrers. The stirring elements 32 are arranged on a shared stirring shaft 36. The stirring elements 32 are arranged on the stirring shaft 36 above one another. Each of the stirring elements 32 herein implements a stirring step. Moreover each of the stirring elements 32 and/or each stirring step defines at least one compartment, in particular a mixing space, of the container 34. The stirring elements 32 are arranged in the container 34 in such a way that the rotational axis 12 is arranged in parallel to a vertically-arranged container axis. Alternatively it is conceivable to arrange a differing number of and/or differently arranged and/or differently embodied stirring elements, which may in particular comprise a stirring device according to the invention, in a container. It is also conceivable to arrange stirring elements in a container in such a way that they are offset to each other, e.g. offset to each other by 30, 45, 60 and/or 90, and/or in such a way that they are mirror-symmetrical to each other.

[0046] In an operating state, a middle-to-highly viscous medium (not shown) is arranged in the container 34. The middle-to-highly viscous medium comprises in the present case a biomass, in particular implemented as a phase. The middle-to-highly viscous medium flows through the container 34 continuously from top to bottom. A Reynolds number is herein between 30 and 500.

[0047] The stirring system is configured to generate a plug flow. The stirring system and in particular the respective stirring elements 32 is/are configured to generate an at least substantially radial flow and to at least substantially prevent an axial flow which is generated by the stirring elements 32 and which is in particular an additional axial flow. An axial flow component of the middle-to-highly viscous medium and/or a product exchange between the respective compartments herein at least substantially exclusively results from an externally applied continuous flow-through through the container 34, while a product exchange between the respective compartments, which is initiated by the stirring elements 32, is at least substantially avoided. Herein a structural implementation and/or a design of the stirring elements 32 significantly contributes to a stabilization of the respective stirring steps and/or compartments.

[0048] Beyond this, the middle-to-highly viscous medium is mixed, by means of the stirring system, in such a way that a middle dwell time T, in particular of the particles and/or of the volume elements of the middle-to-highly viscous medium, in the respective stirring steps and/or in the respective compartments is at least substantially identical. The middle dwell time T is generally obtained by the following equation:

=V/Q(1)

[0049] Herein V corresponds to a volume of the respective compartment and Q corresponds to a volume flow, which is advantageously induced externally and by which the container 34 is flown through. The middle dwell time T in the respective stirring steps is herein longer, advantageously significantly longer, than a mixing time of the stirring step. In the present case the middle dwell time T is at least 1*, advantageously at least 3* and especially preferentially at least 6*. Advantageously the middle dwell time T herein is maximally 30*, preferably no more than 20* and particularly preferably no more than 10*.

[0050] By means of such a kind of stirrer system, an advantageous mixing performance is achievable, wherein in particular an axial product exchange between the compartments is reducible and an implementation of a close dwell time distribution range is enhanceable.