Classifier wheel with vane surface elements

Abstract

A classifier wheel (2) for a classifier device (1) for classifying milled comminuted product, in particular of particulate bulk material, is disclosed herein. The classifier wheel (2) includes classifier wheel blades (5), which are arranged in the radially outer region of the classifier wheel (2), and vane surface elements (8), which are arranged radially spaced apart from the classifier wheel blades (5) in the radially inner region of the classifier wheel (2). A method of classifying milled comminuted products and a use of vane surface elements (8) for classifying milled comminuted products are also disclosed.

Claims

1. A classifier wheel (2) for a classifier device for classifying milled comminuted products, the classifier wheel (2) comprising: classifier wheel blades (5) arranged in a radially outer region of the classifier wheel (2); and vane surface elements (8) arranged radially spaced apart from the classifier wheel blades (5) in a radially inner region of the classifier wheel (2); a discharge opening (7) arranged in a radially inner region of the classifier wheel (2) and configured to be positioned adjacent to a discharge line of the classifier device; wherein an angle of inclination of the vane surface elements (8) is constant with respect to an axial direction of the classifier wheel (2) in an area spanned by the axial direction and a circumferential direction of the classifier wheel (2); wherein the vane surface elements (8) extend to and terminate at or adjacent to the discharge opening (7) such that the vane surface elements (8) do not extend through the discharge opening (7) or into the discharge line of the classifier device.

2. The classifier wheel according to claim 1, wherein the vane surface elements (8) extend linearly in the axial direction of the classifier wheel (2).

3. The classifier wheel according to claim 1, wherein a radial distance between a radially inner end of the classifier wheel blades (5) and a radially outer end of the vane surface elements (8) is constant along a total axial extension of the classifier wheel (2).

4. The classifier wheel according to claim 1, wherein a radial distance between a radially inner end of the classifier wheel blades (5) and a radially outer end of the vane surface elements (8) is between 3% and 30% of a diameter of the classifier wheel (2).

5. The classifier wheel according to claim 1, wherein the vane surface elements (8) are designed to be curved and/or inclined at least partially with respect to a radial direction of the classifier wheel (2).

6. The classifier wheel according to claim 5, wherein the classifier wheel blades (5) are curved and/or inclined at least partially with respect to the radial direction of the classifier wheel (2), and wherein the inclination of the vane surface elements (8) with respect to the radial direction is larger, at least at radially outer edges of the vane surface elements (8), than the inclination of the classifier wheel blades (5) with respect to the radial direction at least at radially inner edges of the classifier wheel blades (5).

7. The classifier wheel according to claim 1, wherein a radially outer edge of the vane surface elements (8) is curved and/or inclined at least partially with respect to the axial direction of the classifier wheel (2).

8. The classifier wheel according to claim 1, wherein the vane surface elements (8) are at least partially arranged at a central shaft (9) in the classifier wheel (2) at radially inner ends of the vane surface elements (8).

9. The classifier wheel according to claim 1, wherein the vane surface elements (8) extend to a radial center of the classifier wheel (2).

10. The classifier wheel according to claim 1, wherein the vane surface elements (8) are uniformly distributed in the classifier wheel in the circumferential direction.

11. The classifier wheel according to claim 1, wherein the vane surface elements (8) at least partially extend over a total height of an interior of the classifier wheel (2).

12. The classifier wheel according to claim 1, wherein a distance between a radially inner end of the classifier wheel blades (5) and a radially outer end of the vane surface elements (8) is adjustable.

13. The classifier wheel according to claim 1, wherein the vane surface elements (8) comprise at least six vane surface elements (8).

14. A classifier device for classifying milled comminuted products, the classifier device comprising: the classifier wheel (2) according to claim 1; and a vane ring (4) inside of which the classifier wheel (2) is rotatably arranged, wherein a classifying space (6) is embodied between the vane ring (4) and the classifier wheel (2).

15. The classifier device according to claim 14, wherein the discharge line (10) is arranged centrally above the classifier wheel (2).

16. A method for classifying milled comminuted products, including the steps of: supplying the milled comminuted product into a classifier space (6) surrounding a rotating classifier wheel (2), and providing an airflow which flows radially inwardly into the rotating classifier wheel (2) and is then discharged in an axial direction through a discharge opening (7) in the classifier wheel (2) positioned adjacent to a discharge line of a classifier device, wherein the airflow carries along a portion of the milled comminuted product in the axial direction along vane surface elements (8) in a region of the classifier wheel (2) adjacent to the discharge opening (7), wherein an angle of inclination of the vane surface elements (8) is constant with respect to the axial direction of the classifier wheel (2) in an area spanned by the axial direction and a circumferential direction of the classifier wheel (2), wherein the vane surface elements (8) extend to and terminate at or adjacent to the discharge opening (7) such that the vane surface elements (8) do not extend through the discharge opening (7) or into the discharge line of the classifier device.

17. The method according to claim 16, wherein the classifier wheel (2) comprises classifier wheel blades (5) arranged in a radially outer region of the classifier wheel (2), and the vane surface elements (8) are arranged in a radially inner region of the classifier wheel (2) radially spaced apart from the classifier wheel blades (5).

18. The method according to claim 17, further comprising adjusting a radial distance between a radially outer end of the vane surface elements (8) and a radially inner end of classifier wheel blades (5) of the classifier wheel (2) in response to a speed and/or a diameter of the classifier wheel (2).

19. The method according to claim 17, wherein the airflow between the classifier wheel blades (5) is rotationally symmetrical.

20. The method according to claim 17, wherein a radial distance between a radially inner end of the classifier wheel blades (5) and a radially outer end of the vane surface elements (8) is constant along a total axial extension of the classifier wheel (2).

21. The method according to claim 16, wherein the vane surface elements (8) extend linearly in the axial direction of the classifier wheel (2).

22. The method according to claim 16, wherein the vane surface elements (8) extend to a radial center of the classifier wheel (2).

23. The method according to claim 16, wherein the vane surface elements (8) comprise at least six vane surface elements (8).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be further illustrated below with reference to exemplary embodiments which are represented in the following figures. In the figures:

(2) FIG. 1 shows a lateral sectional view of a classifier device according to an embodiment of the present invention;

(3) FIG. 2 shows a horizontal sectional view through the classifier wheel according to FIG. 1;

(4) FIG. 3 shows a sectional view through a classifier wheel according to an embodiment of the invention;

(5) FIG. 4 shows a sectional view through a classifier wheel according to another embodiment of the invention;

(6) FIG. 5 shows a sectional view through a classifier wheel according to another embodiment of the invention;

(7) FIG. 6 shows a lateral sectional view through a classifier device according to a further embodiment of the invention.

DETAILED DESCRIPTION

(8) In FIG. 1, a classifier device 1 according to an embodiment of the invention is shown. The classifier device 1 permits to separate oversized material from undersized material in a classifier airflow, to supply the oversized material again to a milling process, and to carry away the undersized material for further processing. To this end, a classifier wheel 2 is provided which can be rotated about a vertical axis by means of a motor 3. The classifier wheel 2 is arranged within a vane ring 4. Here, an outer ring of classifier wheel blades 5 of the classifier wheel is radially spaced apart from the vane ring 4, so that between the classifier wheel blades 5 and the vane ring 4, a classifying space 6 is formed. A milled comminuted product, in particular particulate bulk material, is carried along by an airflow from radially outside through a vane ring 4 and then enters the classifying space 6. By the rotation of the classifier wheel blades 5 together with the classifier wheel 2, flow conditions are produced in the classifying space which cause coarse proportions of the milled comminuted products to fall downwards, and only comminuted products that have at least a certain fineness are transported radially to the inside into the classifier wheel 2. The classifier air flows through the classifier wheel blades 5 into the interior of the classifier wheel and then through a discharge opening 7 into a subsequent processing device. The subsequent processing device may only consist in the undersized material being piled up, transported further and/or packaged.

(9) Between the vane surface elements 8 and the classifier wheel blades 5, a radial distance 100 is provided. Thereby, the effect of the vane surface elements 8 on the flow of the classifier air through the classifier wheel blades 5 can be reduced, so that a more uniform flow profile is present in the classifying space 6. Nevertheless, the vane surface elements prevent undesired potential eddies from occurring inside the classifier wheel 2, and can advantageously contribute to the energy recovery in view of the flow of the classifier air by reducing the required driving power of the motor 3.

(10) In particular, the vane surface elements 8 are attached or at least connected to the shaft 9 of the classifier wheel. A discharge line for undersized material 10 is provided above the discharge opening 7 by which undersized material with the desired grain sizes is carried away in an airflow. The discharge line 10 is in particular arranged above the classifier wheel.

(11) A funnel 11 can be arranged under the classifier wheel 2 and collect oversized material falling down from the classifying space 6 and supply it to a milling process. In particular, a milling plate can be arranged centrally under the funnel 11, so that the milling stock is centrally supplied to the rotating milling plate and then again comminuted by milling rollers before it is again caught by a classifier airflow and supplied to the classifier device 1. Thus, the milling stock or the comminuted products are guided through the classifier device 1 until the desired comminution stage is reached, so that the corresponding undersized material can pass the classifying space 6 into the interior of the classifier wheel and then be discharged via the discharge line 10.

(12) As is represented in FIG. 1, the vane surface elements 8 extend directly to the discharge opening 7 of the classifier wheel 2. Thus, the classifier airflow in the classifier wheel 2 is guided through the vane surface elements 8 to its discharge opening 7. This prevents the generation of undesired eddies in the classifier wheel 2 and improves the energy recovery from the classifier airflow. The vane surface elements 8 extend over the total height of the classifier wheel 2.

(13) In FIG. 2, the horizontal sectional view A-A through the embodiment of the classifier wheel 2 according to the invention, which is drawn in in FIG. 1, is represented. This classifier wheel 2 includes a central shaft 9 with vane surface elements 8 extending from it in the axial direction. The classifier wheel blades 5 are arranged at a radial distance 100 from the radially outer ends 8 of the vane surface elements 8. The classifier wheel blades 5 are here slightly inclined each in pairs in opposite directions with respect to the radial direction. Furthermore, a higher number of classifier wheel elements 5 than of vane surface elements 8 is provided.

(14) In FIG. 3, a further embodiment of a classifier wheel 2 is represented in a horizontal sectional view. Here, the vane surface elements 8 are fitted with a corrugated profile. Here, the vane surface elements 8 are curved against the intended sense of rotation. That means that the vane surface elements each have different angles with respect to the radial direction over their extensions. Furthermore, the classifier wheel blades 5 are inclined with respect to the radial direction. Here, the angle 200 of the radially outer end of the vane surface elements 8 is larger than the angle 300 of the classifier wheel blades 5 with respect to the radial direction. This permits an advantageous flow profile in the classifying space 6, i.e. radially outside the classifier wheel blades 5.

(15) Between the vane surface elements 8 eddies can still occur, as is indicated in FIG. 3 by way of example. However, these eddies are locally confined and thus cause a clearly lower pressure loss than the eddies in classifier wheels according to prior art.

(16) In FIG. 4, an increased number of vane surface elements 8 is provided to further reduce the formation of eddies inside the classifier wheel 2. Furthermore, FIG. 4 shows, by way of example, how the vane surface elements can be guided to the radial center of the classifier wheel. This is in particular possible if in this region, no shaft 9 is provided, but the shaft is, for example, only flange-mounted axially outside at the classifier wheel 2.

(17) In FIG. 5, a classifier wheel 2 is represented in which a radial distance between the centrally arranged shaft 9 and the vane surface elements 8 is provided. The vane surface elements arranged in the radially central region nevertheless permit an effective reduction of eddies, here, it can be, however, advantageous for the vane surface elements 8 to be guided to the central shaft 9 at least in the region which is adjacent to the discharge opening 7.

(18) The vane surface elements 8 in FIGS. 2 to 5 each extend linearly in the axial direction of the classifier wheel 2.

(19) In FIG. 6, an embodiment is finally shown in which the radially outer edge of the vane surface elements is inclined with respect to the axial direction. In particular, the surface of the vane surface elements 8 increases towards the discharge opening, so that in those regions where an increased flow of air is present, an effective suppression of air whirls is possible. As was shown above, the vane surface elements 8 cannot only be employed for suppressing eddy currents, but also be driven by the airflow and thus at least reduce the power input via the motor 3 for driving the classifier wheel. Moreover, by the spacing of the vane surface elements 8 from the classifier wheel blades 5, a reaction of the vane surface elements to the classifying space 6 can be reduced. It can in particular be prevented that a non-uniform flow of air is present in the circumferential direction in response to the vane surface elements 8 in the classifying space 6.