Stirrer arrangement

Abstract

The invention relates to a stirrer arrangement (1) having a shaft (11), which can be driven rotatably about an axis of rotation (A), having a drive device (10), which is arranged at a first shaft end and is intended for driving the shaft (11), having a hub body (9), which is arranged at a second shaft end (12) for conjoint rotation with the shaft (11), and having at least two blades (7), which are arranged on the hub body (9) and extend substantially radially from the hub body (9), as seen in relation to the axis of rotation (A), wherein each of the blades (7) has a foot (13) for fastening on the hub body (9) and also, along the substantially radial extent, has a leading-edge region (14) and a trailing-edge region (15), which is located opposite the leading-edge region (14). According to the invention, the hub body (9) has a wall (17), in which depressions (19) for receiving the blade feet (13) are provided. Also provided, on the outer side of the wall (17), are set-back portions (26), which reach up to a sub-portion of the depressions (20), wherein, in the vicinity of the foot (13), each blade (7) has an extent which projects beyond the foot (13), is formed substantially by the leading-edge region (14) and projects into the respective set-back portion (26).

Description

[0001] Description

[0002] Agitator arrangement

[0003] The invention relates to an agitator arrangement, with a shaft which can be driven rotatably about an axis of rotation, a drive device arranged at a first shaft end for driving the shaft, a hub body arranged at a second shaft end in a rotationally fixed manner with the shaft, at least two blades arranged on the hub body and extending from the hub body essentially in the radial direction with respect to the axis of rotation, wherein each of the blades has a foot for attachment to the hub body and, along the essentially radial extent, a leading edge region and a trailing edge region opposite the leading edge region.

[0004] Such agitators, also known as flow accelerators, are used in many areas, e.g., for the recirculation of activated sludge in aeration tanks, for pumping rainwater, river water, surface water, and polder water, and for generating flow in water bodies. The agitators are designed to achieve good flow control in the corresponding tanks or systems in order to solve the respective process engineering task, for example, the effective mixing of multiple phases.

[0005] The agitators are typically mounted on a free-standing agitator stand, as known from EP 2 328 676 A1, or fixed to a tank wall by means of a guide and support tube arrangement, as known, for example, from EP 2 659 959 A1. EP 2 689 831 A1 describes a stirring device mounted on a tank cover. Agitator arrangements are also known in which only the propeller with the shaft is located inside the tank, while the drive is located outside the tank, i.e., in the case of long-shaft agitators, in a horizontal or vertical installation position.

[0006] From EP 3 066 188 A1 a stirring device is known in which each stirring blade is fastened to a receiving device, wherein several receiving devices form an axle receptacle into which a hub attached to the drive shaft is inserted and screwed thereto.

[0007] Due to the separate manufacturing of the hub body and propeller blades, as described in EP 3 066 188 A1, a gap is created at the contact surface between the two components. Any dirt particles and fibers present in the incoming flow can penetrate the gap and become lodged there. Long fibers, in particular, adhering to the rotating components in this area can have a negative impact on the performance and operational reliability of the agitator.

[0008] Particularly heavy contamination can ultimately require unscheduled maintenance or cleaning operations, which are usually associated with downtime and thus costs for the plant operator

[0009] The present invention is based on the object of mitigating or even completely eliminating the deficiencies of the devices known from the prior art. Specifically, it is an object of the present invention to provide an agitator assembly in which the aforementioned fouling mechanisms are reduced and efficiency is increased.

[0010] This object is achieved by an agitator having the feature of claim 1, according to which the hub body has a wall in which recesses are provided for receiving the vane feet and recesses are provided on the outside of the wall, which recesses extend up to a partial section of the recesses, wherein each vane near the foot has an extension projecting beyond the foot, formed essentially by the leading edge region, which projects into the respective recess.

[0011] The recess is modeled on the leading edge contour of the propeller profile and, in conjunction with the three-dimensional leading edge design, allows dirt particles and fibers to slide off. The recess also generates secondary flows or turbulence, which prevents dirt from adhering to the gap area.

[0012] In an advantageous embodiment, the hub body comprises a substantially cup-shaped base body. This allows for very simple assembly and disassembly of the entire agitator, and also of the individual blades if necessary.

[0013] To ensure that the interior of the hub body remains largely free of fibers, the hub body is closed with a cover at its free end.

[0014] Furthermore, for easy assembly and disassembly, the hub body comprises a base element with a shaft holder into which the shaft can be inserted and connected to the hub body by means of a screw connection.

[0015] Furthermore, the base element is essentially conical, with the shaft mount having a substantially cylindrical configuration. The conical design of the base element significantly simplifies the assembly and disassembly of the vanes with the hub body installed.

[0016] Further advantages, features and effects of the present invention will become apparent from the following figures.

[0017] Fig. 1 is a perspective view of the agitator according to the invention, Fig. 2 is a longitudinal section through the hub body,

[0018] Fig. 3 is a perspective detailed view of the hub body and Fig. 4 is the hub body of the agitator according to the invention with blades attached thereto.

[0019] Fig. 1 shows an agitator assembly 1 with an agitator stand 2, which in this embodiment is manufactured as a one-piece concrete or mineral cast component and has a base part 3 and a receiving part 4. The contour of the receiving part 4 is designed such that it can accommodate a submersible motor agitator 5 and fix it in its working position.

[0020] The submersible mixer 5 has a stirring element 6, which here is designed as a propeller with three blades 7. A guide element 8, which is only partially shown in Fig. 1, protrudes above the mixer stand 2. This guide element 8, which here is designed as a steel tube with a square cross-section, serves solely to guide the submersible mixer 5 during lowering or lifting.

[0021] The propeller or stirring element 6 comprises a hub body 9 on which the blades 7 are arranged.

[0022] The agitator 1 has a drive device 10 with a motor and gear (not shown in detail). A shaft 11, shown in Fig. 2, is connected to the drive device by a first shaft end (not shown) and can be driven rotatably about a rotational axis A.

[0023] Figure 1 shows an agitator assembly 1 with an agitator stand 2, which is manufactured as a one-piece concrete or mineral cast component. However, the subject matter of the invention can also be used in agitator assemblies in which only the propeller with the shaft is arranged inside the tank, while the drive is located outside the tank.

[0024] As can further be seen from Fig. 2, which shows the hub body 9 in a longitudinal section, the hub body 9 is arranged at a second shaft end 12 in a rotationally fixed manner with the shaft 11. At least two, but three shown in Fig. 1, vanes 7 are arranged on the hub body 9 and extend from the hub body 9 essentially in the radial direction with respect to the axis of rotation A. Each of the vanes 7 comprises a base 13 for attachment to the hub body 9. The vanes 7 have, along the essentially radial extent, a leading edge region 14 and a trailing edge region 15 opposite the leading edge region 14. The agitator 6 rotates counterclockwise from the perspective of the drive device 10.

[0025] As can be seen from Fig. 2, the hub body 9 comprises a substantially cup-like base body 16 with a wall 17. The base body 16 or the wall 17 has a first body portion 18 with a reduced inner diameter and a second body portion 19 with an enlarged inner diameter.

[0026] In the first body section 18, the hub body 9, in particular the wall 17, has a plurality of recesses 20 corresponding to the number of vanes 7. The recesses 20, in turn, each have a contact surface 21 against which the vane base 13 accommodated in the recess rests. The contact surfaces 21 are formed substantially parallel to the rotational axis A. At the free end of the second body section 19, the hub body 9, in particular the cup-like base body 16, can be closed with a cover 22.

[0027] The hub body, in particular the base body 16, comprises a base element 23 with a shaft receptacle 24, into which the shaft 11 can be inserted and connected to the hub body 9 by means of a screw connection. The base body 16 coaxially surrounds the shaft receptacle 24, via which the hub body 9 can be arranged or fastened to the shaft 11. The base element 23 is essentially conical, with the shaft receptacle 24, which is formed integrally with the base element 23, having an essentially cylindrical configuration.

[0028] From Fig. 3, it can be seen that a plurality of through-holes 24 are provided in the region of the recesses 20, which extend from the contact surface 21 into the interior of the hub body 9. The vanes 7 are arranged or fastened to the base body 16 of the hub body 9 by means of connecting elements 25. The connecting means 25 can, for example, comprise screws or threaded bolts with nuts. The screws or threaded bolts extend through the through-holes 24 and are screwed into corresponding threaded holes (not shown) in the vane feet 13.

[0029] In the region of the first body portion 18, the hub body 9, in particular the base body 16, has a recess 26 on the outer side of the wall 17, which extends to a part of the recess 20. The recess 26 has a contact surface 27.

[0030] Fig. 4 shows a side view of the hub body 9 with vanes 7 arranged thereon. Each of the vane feet 13 is embedded in one of the recesses 20. Near the foot 13, the vane 7 has an extension projecting beyond the foot 13, essentially formed by the leading edge region 14. The extension formed by the leading edge region 14 projects into the recess 26. A portion of the leading edge region 14 thereby comes into contact with the contact surface 27 shown in Fig. 3.

Claims

Claims: Agitator arrangement (1) comprising a shaft (11) rotatably driven about an axis of rotation (A), a drive device (10) arranged at a first shaft end for driving the shaft (11), a hub body (9) arranged at a second shaft end (12) rotatably with the shaft (11), at least two wings (7) arranged on the hub body (9) extending substantially radially from the hub body (9) with respect to the axis of rotation (A), each of the wings (7) having a foot (13) for attachment to the hub body (9) and, along its substantially radial extent, an upstream edge region (14) and an downstream edge region (15) opposite the upstream edge region (14), characterized in that the hub body (9) has a wall (17) in which recesses (19) are provided for receiving the wing feet (13) and that on the outside of the wall (17) Returns (26) are provided,extending to a partial section of the recesses (20), each wing (7) having, near the base (13), an extension projecting beyond the base (13), formed essentially by the leading edge region (14), which projects into the respective recess (26). Agitator arrangement (1) according to claim 1, characterized in that the hub body (9) comprises a substantially cup-shaped base body (16).

3. Agitator assembly (1) according to one of claims 1 or 2, characterized in that the hub body (9) is closed at a free end with a cover (22).

4. Agitator assembly (1) according to one of claims 1 to 3, characterized in that the hub body (9) comprises a base element (23) with a shaft receptacle (24).

5. Stirring arrangement (1) according to one of claims 1 to 4, characterized in that the bottom element (23) is essentially conical, wherein the shaft receptacle (24) has an essentially cylindrical design.

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