WO2009018915A1

WO2009018915A1 - Stirring device for activated sludges

Info

Publication number: WO2009018915A1
Application number: PCT/EP2008/005923
Authority: WO
Inventors: Marcus HÖFKEN
Original assignee: Invent Umwelt- Und Verfahrenstechnik Ag
Priority date: 2007-08-09
Filing date: 2008-07-18
Publication date: 2009-02-12
Also published as: BRPI0814951A2; BRPI0814951B1; ATE510613T1; EP2175973B1; EG25611A; CN101778665A; JP2010535610A; ES2366873T3; EP2175973A1; CN101778665B; ZA201000605B; US20100196165A1; DK2175973T3; JP5307812B2; IL203596A; PL2175973T3

Abstract

The invention relates to a stirring device for activated sludges comprising a hyperboloid stirring body (1) attached to a shaft (2), wherein a plurality of transport ribs (3) are provided on the top (O) of the stirring body (1) running toward the circumferential boundary (UM) thereof, wherein the transport ribs (3) have an oblique course, at least in sections, relative to a radial direction, and wherein the oblique position of the transport ribs (3) is selected such that, when the stirring body (1) rotates in a predetermined rotational direction (R), a flow (S) is generated that is directed outward away from the circumferential boundary (UM) of the stirring body (1). In order to improve the efficiency of the stirring device, the invention proposes that a flow guidance device (7) for guiding the flow (S) generated by the stirring body (1) be provided in a plane running substantially perpendicular to the shaft (2), said flow guidance device surrounding the circumferential boundary (UM) of the stirring body (1) and being relatively fixed thereto.

Description

Stirring device for activated sludge

The invention relates to a stirring device for activated sludge according to the preamble of patent claim 1.

Such a device is known for example from DE 42 18 027 Al or DE 198 26 098 C2. In the known stirring device, a hyperboloid-like stirring body is attached to a shaft. On an upper side of the stirring body a plurality of radially inclined transport ribs are provided. During a rotation of the stirring body, due to its hyperboloidal shape and due to the action of the transport ribs, a flow directed away from the peripheral edge of the stirring body is generated in a stirring medium surrounding liquid medium.

The invention is based on the object to provide a stirring device with improved stirring efficiency.

This object is solved by features of claim 1.

Advantageous embodiments emerge from the claims 2 to 14.

According to the invention, provision is made for a flow guiding device surrounding the peripheral edge of the stirring body and relatively fixed to guide the flow generated by the stirring body in a plane extending substantially perpendicular to the shaft. Thus, the stirring efficiency can be improved in a simple and cost-effective manner.

The invention is based on the finding that the stirring efficiency increases with an increasing radial range of the flow directed away from the peripheral edge of the stirring body. It has been observed that as a result of the flow, forms a not inconsiderable suction below the stirring body, which causes a reverse flow opposite to the flow. The return flow slows the flow and inhibits the formation of a wide radial range of the same.

According to the invention, by means of the proposed flow guiding device, the flow generated by the stirring body is guided in a plane extending substantially perpendicular to the shaft, in particular the formation of flow components directed obliquely to the bottom of the basin is counteracted. A mutual influence of the flow and the return flow is reduced. Thus, the radial range of the flow can be significantly improved.

The transport ribs expediently form, at least in the region of the peripheral edge with the radial direction, a first skew angle of -30 ° to -90 °, preferably -40 ° to -80 °. With the above-mentioned negative sign before the amount of the first skew angle, it is indicated that this opens with respect to the radial direction opposite to the direction of rotation.

According to an advantageous embodiment, the flow-guiding device has an annular gap surrounding the peripheral edge, which is formed by lower and upper flow-guiding means arranged coaxially with the shaft. The flow-guiding means may be made of plastic, in particular fiber-reinforced plastic, or also of metal, preferably of stainless steel, flat elements. Expediently, the flow-guiding device forms an assembly unit. For this purpose, the upper and lower flow guiding means can be connected to each other via connecting means. The connecting means may be substantially radially extending walls. The provision of such walls contributes to an improved flow tion in the radial direction and thus further to increase the scope of the flow.

According to an alternative embodiment, it is provided that the connecting means are obliquely extending first inclined walls with respect to the radial direction, which form with the radial direction a second skew angle of + 30 ° to + 90 °, preferably + 40 ° to + 80 °. The positive sign used before the magnitude of the aforementioned second skew angle indicates that the second

Inclination angle with respect to the radial direction in the direction of rotation opens. The second skew angle is particularly chosen so that it is directed substantially parallel to the flow generated by the stirring body. As a result, a deflection of the flow is avoided. This can further improve the radial range of the flow.

According to a further embodiment, the lower flow-guiding means is an annular disc extending substantially parallel to the plane. A breakthrough provided in the center of the annular disk allows passage of the liquid medium flowing back at the bottom of the tank into the area of action of the stirring body and thus its acceleration in a radially outward-pointing direction.

On an underside of the lower fluid facing away from the upper fluid, support elements for supporting on a bottom of the basin may be provided, such that a further annular gap is formed between the bottom and the lower fluid. The further annular gap allows the substantially unimpeded formation of the return flow in a region below the stirring body.

The support means may essentially be radially extending further walls. Such other walls set the return flow against a low flow resistance and thus contribute to the formation of a flow with an improved range at.

According to an alternative embodiment, the support means with respect to the radial direction obliquely extending second oblique walls, the radial direction with a third skew angle of -30 ° to -90 °, preferably from -40 ° to -80 °, form. The negative sign in front of the amount of the aforementioned third skew angle again indicates that it opens with respect to the radial direction opposite to the direction of rotation of the stirring body. The proposed skew of the second inclined walls is chosen in particular so that it runs parallel to the direction of a ground-level return flow. This avoids a deflection of the return flow. As a result, the return flow is counteracted with the least possible resistance, which in turn allows the radial range of the flow to be increased.

According to a particularly advantageous embodiment, a gap width of the annular gap running essentially parallel to the shaft widens toward the peripheral edge of the stirring body. In this case, the annular gap forms an annular nozzle with which the flow directed away from the peripheral edge of the stirring body is guided not only in a plane substantially parallel to the pelvic floor, but also accelerated in this plane. This again contributes significantly to the improvement of the radial range of the flow.

The transport ribs can bend towards the peripheral edge from an approximately radial direction in an opposite to the direction of rotation directed approximately tangential direction. Further, they may extend only in an outer radial portion of the upper side. In this embodiment, one of Peripheral edge of the stirring body directed away flow can be generated at a particularly high speed.

According to a further embodiment, a plurality of substantially radially extending shear ribs are provided on a further underside opposite the upper side. A height of the shear ribs may increase towards the peripheral edge of the stirring body. Such shear ribs serve to distribute air, which can be supplied via an air supply line in the region below the stirring body. This can do that

Stirrer surrounding liquid medium are not only efficiently transported with a high reach in a radial direction, but it can also be mixed with the finest air bubbles.

An embodiment of the invention will be explained in more detail with reference to the drawing. Show it:

1 is a partial cross-sectional view of a stirring device,

2 is a complete cross-sectional view of the stirring device of FIG. 1,

Fig. 3 is a perspective view of the stirring device and

Fig. 4 is a plan view of another stirring device.

Fig. 1 shows a side view of a hyperboloid-like stirring body 1, which is fixed to a shaft 2. At a

O top of the stirring body 1 are provided a radially outer portion transport ribs 3, which extend to a peripheral edge UM. The transport ribs 3 initially run in a substantially radial direction and then bend counter to a direction of rotation R in an in Substantial tangential direction. Shear ribs 4 are provided on an underside U in the vicinity of the peripheral edge UM, the height of which increases in a radially outward-pointing direction. As can be seen in particular from FIG. 2, the stirring body 1 is formed from a hyperboloid-shaped stirring body wall 5. He therefore has on its underside U a funnel-like recess 6.

As is apparent from FIGS. 1 to 3, the peripheral edge UM of the stirring body 1 is surrounded by a flow guiding device 7. The flow guiding device 7 consists of a lower annular disc 8 and an annular disk-like flow guide element 9 arranged above it, which is held at a distance from the annular disc 8 by means of radially extending walls 10. Between the annular disc 8 and the flow guide 9, an annular gap 11 is formed, which surrounds the peripheral edge UM. The flow guiding element 9 is bent upward in a direction pointing toward the shaft 2, so that the annular gap 11 widens in a direction towards the peripheral edge UM. The annular disc 8 is over more walls

12, which are also arranged substantially radially extending, supported on a bottom B of a (not fully shown) basin. A height of the further walls 12 defines a further annular gap 13 between the bottom B and the annular disk 8.

The function of the stirring device is the following:

By a rotation of the stirring body 1 in the direction of rotation R, a flow S pointing away from the peripheral edge UM is generated in particular by the action of the transport ribs 3. The flowing liquid medium, eg sewage sludge, sewage or the like. , is forced through the annular gap 11. Because of the tapering cross section of the annular gap 11, the flowing medium is accelerated. off from this, the flow S is imposed on a direction which runs essentially parallel to the bottom B.

As a result of the forming flow S creates a suction below the agitator 1, which in turn generates a flow S opposite reverse flow RS. The return flow RS, which is also directed essentially parallel to the bottom B, enters the flow guiding device 7 through the lower annular gap 13 and is then deflected by the action of the stirring body 1 in order to emerge again from the annular gap 11 with the flow S.

By means of a (not shown here) air supply line of the recess 6 air can be supplied. For this purpose, the air supply line can extend substantially parallel to the bottom B and bend below the shaft 2 in the direction of the recess 6. The medium flowing back according to the return flow RS can be mixed with the supplied air at the exit through the annular gap 11 by means of the shear ribs 4. It then passes through the annular gap 11, a liquid medium containing finest air bubbles.

With the proposed flow guiding device 7, the flow S and the return flow RS are guided in parallel planes lying one above the other. This reduces interactions between the two flows S, RS. A radial range of the flow S and thus the efficiency of the stirring device are improved.

Fig. 4 shows a plan view of another stirring device. As far as the components of the further stirring device are identical or substantially similar to the components of the stirring device shown in Figs. 1 to 3, the reference numerals used there have been used. The reference character α denotes a first skew angle. net, which is formed between a portion of the transport ribs 3 in the region of the peripheral edge UM and a radial direction RR. The first skew angle α is in a range of -30 ° to -90 °, here about at -45 °.

The further stirring device differs from the stirring device shown in FIGS. 1 to 3 essentially by an oblique position of the walls 5 and of the further walls 12. First oblique walls 10a are indicated in FIG. 4 by long broken lines. They connect the flow guide 9 with the washer 8 arranged underneath. The horizontally extending first inclined walls 10a form with a radial direction RR a second skew angle β of + 30 ° to + 90 °, in this case approximately + 45 °. Second inclined walls 12a support the annular disc 8 with respect to the bottom B from. The also horizontally arranged second inclined walls 12a form with the radial direction RR a third skew angle Y in the range of -30 ° to -90 °, here about from -45 °.

As can be seen from FIG. 4, the first oblique walls 10a extend approximately perpendicular to the second oblique walls 12a. The flow S generated by the stirring body 1 runs approximately parallel to the first inclined walls 10a. The return flow RS runs approximately parallel to the second inclined walls 12a.

As can further be seen from FIG. 4, in particular the first inclined walls 10a are not arranged parallel to one another. An annular gap section formed by the first inclined walls 10a widens in the radial direction. As a result, the velocity of the flow through the annular gap portion decreases in the radial direction. To counteract this disadvantage and to achieve a particularly high range of flow S, according to a further embodiment, an auxiliary wall 10b may be provided, which parallel to the first inclined wall 10a arranged opposite to the direction of rotation R runs and with the next first inclined wall 10a near the peripheral edge UM has a common edge. With this configuration it is achieved that an entrance surface of an annular gap section in the vicinity of the peripheral edge UM corresponds approximately to an exit surface of the annular gap section. Thus, a slowing of the flow S during passage through the annular gap 11 can be avoided.

LIST OF REFERENCE NUMBERS

1 stirring element

2 shaft 3 transport rib

4 shear rib

5 wall

6 recess

7 flow guide device 8 annular disc

9 flow guide

10 wall

10a first sloping wall

10b auxiliary wall 11 annular gap

12 more wall

12a second oblique wall

13 further annular gap

O top

UM peripheral edge

U bottom

R rotation direction

S flow RS return flow

B floor

RR radial direction α first skew angle β second skew angle Y third skew angle

Claims

claims

1. agitating device for activated sludge having a hyperboloid-like agitating body (1) attached to a shaft (2),

wherein on an upper side (O) of the stirring body (1) a plurality of its peripheral edge (UM) extending towards transport ribs (3) are provided,

wherein the transport ribs (3) extend obliquely at least in sections with respect to a radial direction, and

wherein a first inclined position of the transport ribs (3) is selected so that during a rotation of the stirring body (1) in a predetermined direction of rotation (R) from the peripheral edge (UM) of the stirring body (1) outwardly directed flow (S) is generated .

characterized in that

a flow guide device (7) surrounding the peripheral edge (UM) of the agitating body (1) and relatively stationary, for guiding the flow (S) generated by the stirring body (1) in a plane substantially perpendicular to the shaft (2).

2. Stirring device according to claim 1, wherein the transport ribs at least in the region of the peripheral edge (UM) with the Radi alrichtung a first skew angle (α) of -30 ° to -90 °, preferably from -40 ° to -80 ° form.

3. stirring device according to one of the preceding claims, wherein the flow guiding device (7) has a peripheral edge (UM) surrounding annular gap (11) which axially and with the shaft (2) arranged lower and upper flow guiding means is formed.

4. Stirring device according to one of the preceding claims, wherein the upper and lower Strömungsleitmittel are connected to each other via connecting means.

5. Stirring device according to one of the preceding claims, wherein the connecting means are substantially radially extending de walls (10).

6. Stirring device according to one of the preceding claims, wherein the connecting means with respect to the radial direction obliquely extending first inclined walls (10 a) which with the radial direction a second skew angle (ß) of + 30 ° to + 90 °, preferably from + 40 ° to + 80 °, form.

7. Stirring device according to one of the preceding claims, wherein the lower Strömungsleitmittel is a substantially parallel to the plane extending annular disc (8).

8. Stirring device according to one of the preceding claims, wherein at one of the upper Strömungsleitmittel (9) facing away from the lower Strömungsleitmittels support elements for supporting on a bottom (B) of a basin are provided such that between the bottom (B) and the lower Strömungsleitmittel a further annular gap (13) is formed.

9. Stirring device according to one of the preceding claims, wherein the support means are substantially radially extending further walls (12).

10. stirring device according to one of the preceding claims, wherein the support means with respect to the radial direction obliquely extending second inclined walls (10 b), which with the Radi- a third skew angle (y) from -30 ° to -90 °, preferably from -40 ° to -80 ° form.

11. Stirring device according to one of the preceding claims, wherein a substantially parallel to the shaft (3) extending gap width of the annular gap (11) widens towards the peripheral edge (UM) of the stirring body (1).

12. Stirring device according to one of the preceding claims, wherein the transport ribs (3) to the peripheral edge (UM) bend from an approximately radial direction in an opposite to the direction of rotation (R) directed approximately tangential direction.

13. Stirring device according to one of the preceding claims, wherein the transport ribs (3) extend only in an outer radial portion of the upper side (O).

14. Stirring device according to one of the preceding claims, wherein on one of the upper side (O) opposite another underside (U) a plurality of substantially radially extending shear ribs (4) are provided.

15. Stirring device according to one of the preceding claims, wherein a height of the shear ribs (4) to the peripheral edge (UM) of the stirring body (1) increases towards.