GB2165462A - Mixing apparatus stator device - Google Patents

Abstract

A stator device for a mixing apparatus is in the form of a generally cylindrical body 10 having openings 26 through the cylindrical wall thereof. An apertured screen 25 is arranged within the body 10 against the inner cylindrical wall thereof and is supported between the openings 26 by solid portions 26A of the body. A flange 27 of the screen co-operates with means to prevent axial and rotational movement of the screen relative to the body. Also described is a mixing apparatus incorporating the stator 10. <IMAGE>

Description

SPECIFICATION Mixing Apparatus Stator Device This invention relates to multi-purpose mixing apparatus for mixing together materials in liquid and solid form and including a bladed rotor of which radially outward portions co-operate with apertures in an adjacent cylindrical wall of a surrounding stator device to force material to be mixed outwardly through said apertures. The invention is particularly applicable to a stator device for use in such an apparatus.

It has been proposed to use a separate annular apertured screen component which is arranged to form part of the surrounding wall of the stator device and co-operate with the rotor. However, a problem can arise due to outward pressure of the material being mixed sometimes causing bursting of the screen and also due to an unwanted tendency for the screen to rotate, in use.

An object of the invention is to provide an improved stator device and a mixing apparatus incorporating such a device, in which the aforesaid problems are minimised or avoided.

According to the invention, a stator device for a mixing apparatus comprises a generally cylindrical body having at least one opening through a wall portion thereof, an apertured screen arranged in relation to the body so as to cover said opening whilst engaging support means so as to resist generally radially outwardly directed forces arising during passage of material through the screen during mixing, and means for positively retaining the screen against axial and rotational movement relative to the body.

Preferably, the or each opening in the body is a circumferential slot and the screen is a generally annular element disposed internally around the body, being afforded support against said radial forces by solid wall portions between the slots.

In one convenient arrangement, the screen is provided with at least one radially extending portion, preferably in the form of a continuous peripheral radial flange, which co-operates with means on the body to resist both axial and rotational displacement of the screen relative to the body..Typically, the body has a peripheral radial flange for engagement by said screen flange the body flange having projecting axially directed screw members which pass through apertures in the screen flange to prevent rotation of the screen relative to the body.

From another aspect of the invention, mixing apparatus comprises a stator device having a generally cylindrical body with at least one opening through a wall portion thereof, an apertured screen arranged in relation to the body so as to cover said opening whilst engaging support means so as to resist generally radially outwardly directed forces arising during passage of material through the screen during mixing, means for positively retaining the screen against axial and rotational movement relative to the body, a rotor having blades arranged with their radially outer extremities adjacent to said screen, and drive means for rotating said rotor relative to the stator device.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure lisa perspective view of one form of the mixing apparatus of the invention, illustrated in position within a container for material to be mixed; Figure 2 is a side elevation to an enlarged scale of part of the mixing apparatus of Figure land Figure 3 is a longitudinal cross section of the assembly of Figure 2.

Referring to Figure 1, the mixing apparatus illustrated therein has a mixing head, illustrated generally by the reference 1 connected buy a plurality of support struts 2 to a motor support 3 which carries an electric motor 4 connected by a depending drive shaft 5 to a rotor within the mixer head 1, which is illustrated more clearly in Figures 2 and 3. A control plate 6 is provided, operable by a rod 7 so as to be movable between the position illustrated in which it closes an inlet to the mixer head 1 and an axially displaced position in which said inlet is open. The shaft 5 is supported in bearings 8 and 9 carried respectively by the motor support 3 and mixer head 1.

The mixer head 1 includes a cylindrical stator 10 within which rotates a bladed rotor 11 (Figure 3) secured to the adjacent end of the shaft 5 by a nut 11A or other suitable means so as to be drivable by the motor 4. The stator 10 is securely fixed, by way of a radial flange 12 thereof to a spider indicated generally at 13 which is in turn secured at an annular peripheral portion 14 thereof to the supports 2, the supports having threaded end portions 15 engaged in correspondingly threaded holes in the portion 14 of the spider. The spider has a centrally located boss which forms the lower shaft bearing 9, the bearing being connected by a plurality of radial arms, of which one can be seen at 16, the spider peripheral part 14.

The rotor 11 includes a plate 17 which is substantially co-extensive with the area circumscribed by the internal wall 18 of the stator and which effectively divides the stator into an upper chamber 19 above the plate 17 and a lower chamber 20 below the plate. The rotor carries two sets of blades respectively at either side of the plate 17, the lower blades 21 being aligned with a row of relatively large apertures 22 formed through the wall of the stator and the radially outer edges of the blades being located close to those apertures. The upper blades 23 are similarly arranged in relation to apertures 24 formed in a screen component 25 which lies against the internal wall 18 of the stator at a location opposite to a plurality of elongate slots 26 (Figure 2), the screen component being held in position in the manner two be described.

The screen component 25 is provided with a peripheral radially extending flange 27 which lies on top of the statorflange 12. Holes are provided through the flange 27 to permit the passage therethrough of screw elements 28 which are long enough to extend also through the flange 16 of the spider 13 so as to protrude beyond the outer surface of the latter for co-operation with nuts 29. Since the flange 27 of the screen component lies between the statorflange 12 and spider flange 16 and is clamped by the nuts 29, it is effectively trapped and cannot therefore move axially. The lower end of the screen component rests on an internal shoulder 30 of the stator and is thereby afforded additional axial support.The screw members 28 engage closely within the corresponding holes therefor in the screen component flange 27 and thus act to prevent relative rotation between the stator and screen component. It will be understood that the plate 6 lying on top of the spider 13 is provided with cut-out portions 6A to correspond with the positions of the nuts 29 and supports 2 so that axial movement of the plate 6 under the action of the control rod 7 is not impaired.

In use, the mixing head is lowered into a vessel 1A, indicated in broken lines in Figure 1, containing materials to be mixed, which may be, for example, a relatively lumpy solid and a liquid in which it is to be dissolved. A mixing operation would normally start with the control plate 6 in the position shown in which it effectively blocks off entry of material to the upper chamber 20' and rotation of the rotor by the motor 4 causes a flow of material to be induced into the lower chamber 20 and to be expelled radially outwardly through the openings 22. The close proximity of the radially outer edges of the blades 21 to the apertures 22 in the inner wall 18 of the stator produces a shearing action between the blade edges and the peripheral edges of the apertures.

Because of the relatively large size of the apertures 22, a coarse mixing effect takes place during this phase of the operation accompanied by break-down of any relatively large pieces of solid material due to the aforesaid shearing effect. When this has been continued for long enough to produce thorough mixing and the required degree of material break down, the control rod 7 is operated to raise the control plate 6 so as to permit ingress of material into the upper chamber 20'. A similar action to that already described then occurs between the upper blades 23 and the apertures 24 of the screen component 25 and since the apertures 24 are very much smaller than the apertures 22, a more thorough mixing and possibly further break down of solid particles occurs during passage of the materials through the apertures 24 under the action of the blades 23.Because of the secure manner in which the screen component 25 is mounted on the stator body 10, it is found that no axial or rotational movement of the screen occurs relative to the body even under very severe mixing conditions.

Moreover, the radial support afforded to the screen by body portions 26A between the slots 26 enables the screen component to withstand much higher pressures than hitherto without bursting.

It will be understood that the screen component 25 may, if required, be located at the presently open end of the stator, the stator then being provided at that end with a radial flange to which the screen component would be clamped by a suitable clamping ring, for example.

The apparatus described above is readily adaptable to suit a variety of conditions by interchanging screen components to vary the number and sizes of aperture. It is possible for a screen to have aperture of different sizes either randomly or regularly arranged. The drive shaft 5 may carry one or more additional rotors for cooperation with further corresponding holes in the stator.

Claims (9)

1.A A stator device for a mixing apparatus comprising a generally cylindrical body having at least one opening through a wall portion thereof, an apertured screen arranged in relation to the body so as to cover said opening whilst engaging support means so as to resist generally radially outwardly directed forces arising during passage of material through the screen during mixing, and means for positively retaining the screen against axial and rotational movement relative to the body.

2. A stator according to Claim 1 wherein the body is provided with a plurality of said openings in the form of circumferential slots and the screen is a generally annular element disposed internally around the body, being afforded supportagainst said radial forces by solid wall portions of the body between the slots.

3. A stator according to Claim 1 or Claim 2 wherein the screen is provided with at least on radially extending portion which co-operates with means one the body to resist both axial and rotational displacement of the screen relative to the body.

4. A stator according to Claim 3wherein said radially extending portion of the screen is a peripheral radial flange and the body is provided with a similar flange for engagement by the screen flange, the body flange having projecting axially directed screw members which pass through apertures in the screen flange to prevent rotation of the screen relative to the body.

5. A stator substantially as hereinbefore described with reference to the accompanying drawings.

6. Mixing apparatus comprising a stator device having a generally cylindrical body with at least one opening through a wall portion thereof, an apertured screen arranged in relation to the body so as to cover said opening whilst engaging support means so as to resist generally radially outwardly directed forces arising during passage of material through the screen during mixing, means for positively retaining the screen against axial and rotational movement relative to the body, a rotor having blades arranged with their radially outer extremities adjacent to said screen, and drive means for rotating said rotor relative to the stator device.

7. Mixing apparatus according to Claim 6 wherein the rotor has a generally planar portion with blades on both major surfaces thereof, the blades on one side of the rotor co-operating with the screen and the blades on the other side co-operating with a series of apertures formed in the stator body.

8. Mixing apparatus according to Claim 7 wherein said rotor planar portion divides the stator into a pair of chambers partially defined respectively by the screen and by a wall portion of the body which contains said series of apertures.

9. Mixing apparatus substantially as hereinbefore described with reference to the accompanying drawings.