Stirring device for activated sludges

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.

1 . Stirring device for activated sludges comprising a hyperboloid-like stirring body ( 1 ) attached to a shaft ( 2 ),
 wherein on an upper side (O) of the stirring body ( 1 ) a plurality of transport ribs ( 3 ) running towards its circumferential boundary (UM) is provided,   wherein the transport ribs ( 3 ) are running inclined at least in sections with respect to a radial direction and   wherein a first inclination of the transport ribs ( 3 ) is selected in such a manner that, when the stirring body ( 1 ) rotates in a predetermined direction of rotation (R), a flow (S) directed away from the circumferential boundary (UM) of the stirring body ( 1 ) to the outside is generated,   characterized in that   a flow guiding device ( 7 ) which surrounds the circumferential boundary (UM) of the stirring body ( 1 ) and which is relatively fixed thereto is provided to guide the flow (S) generated by the stirring body ( 1 ) in a plane running essentially vertically to the shaft ( 2 ).   
   
   
       2 . Stirring device as defined in  claim 1 , wherein the transport ribs form a first angle of inclination (α) of −30° to −90°, preferably of −40° to −80°, with the radial direction at least in the area of the circumferential boundary (UM). 
   
   
       3 . Stirring device as defined in  claim 1  wherein the flow guiding device ( 7 ) has an annular gap ( 11 ) surrounding the circumferential boundary (UM) which is formed by lower and upper flow conducting means arranged coaxially to the shaft ( 2 ). 
   
   
       4 . Stirring device as defined in  claim 1  wherein the upper and lower flow conducting means are connected to each other via means of connection. 
   
   
       5 . Stirring device as defined in  claim 1  wherein the means of connection are essentially radially running walls ( 10 ). 
   
   
       6 . Stirring device as defined in  claim 1  wherein the means of connection are first inclined walls ( 10   a ) running inclined with respect to the radial direction which form a second angle of inclination (β) of +30° to +90°, preferably of +40° to +80°, with the radial direction. 
   
   
       7 . Stirring device as defined in  claim 1  wherein the lower flow conducting means is a ring disk ( 8 ) extending essentially parallel to the plane. 
   
   
       8 . Stirring device as defined in  claim 1  wherein support elements are provided on an underside of the lower flow conducting means pointing away from the upper flow conducting means ( 9 ) for support on a bottom (B) of a basin in such a manner that a further annular gap ( 13 ) is formed between the bottom (B) and the lower flow conducting means. 
   
   
       9 . Stirring device as defined in  claim 1  wherein the means of support are essentially radially running further walls ( 12 ). 
   
   
       10 . Stirring device as defined in  claim 1  wherein the means of support are second inclined walls ( 10   b ) running inclined with respect to the radial direction, which form a third angle of inclination (γ) of −30° to −90°, preferably of −40° to −80°, with the radial direction. 
   
   
       11 . Stirring device as defined in  claim 1  wherein a gap width of the annular gap ( 11 ) running essentially parallel to the shaft ( 3 ) expands towards the circumferential boundary (UM) of the stirring body ( 1 ). 
   
   
       12 . Stirring device as defined in  claim 1  wherein the transport ribs ( 3 ) bend towards the circumferential boundary (UM) from an approximately radial direction in an approximately tangential direction directed opposite the direction of rotation (R). 
   
   
       13 . Stirring device as defined in  claim 1  wherein the transport ribs ( 3 ) only extend in an outer radial section of the upper side (O). 
   
   
       14 . Stirring device as defined in  claim 1  wherein a plurality of essentially radially running shear ribs ( 4 ) is provided on a further underside (U) located opposite the upper side (O). 
   
   
       15 . Stirring device as defined in  claim 1  wherein a height of the shear ribs ( 4 ) increases towards the circumferential boundary (UM) of the stirring body ( 1 ).