Method for stirring a liquid and for injecting a gas into this liquid, suitable for shallow basins

Abstract

The invention relates to a device for stirring a liquid in a reactor and for injecting a gas into the said liquid in order to form a gas-liquid dispersion, comprising a) a drive device ( 1 ) positioned above the reactor, provided with a vertical output shaft ( 2 ) fitted at its lower end with at least one axial flow rotor ( 4 ) immersed in the liquid, b) means for introducing gas ( 3 and 7 ) above the axial flow rotor ( 4 ), c) a deflector ( 5 ) placed above the axial flow rotor ( 4 ) preventing the gas-liquid dispersion from rising, and d) a deflector ( 6 ) placed below the axial flow rotor ( 4 ) converting the axial flow of the said axial flow rotor into a radial flow. This device may be used in shallow basins.

What is claimed is: 
     
         1 . A device for stirring a liquid in a reactor and for injecting a gas into the said liquid in order to form a gas-liquid dispersion, comprising:
 a) a drive device positioned above the reactor, provided with a vertical output shaft fitted at its lower end with at least one axial flow rotor immersed in the liquid;   b) a gas injection device configured to be capable of introducing a gas above the axial flow rotor; and   c) a deflector placed above the axial flow rotor configured to prevent the gas-liquid dispersion from rising,   d) a deflector secured to the vertical output shaft placed below the axial flow rotor and configured to convert the axial flow of the said rotor into a radial flow.   
     
     
         2 . The device of  claim 1 , characterized in that the deflector placed below the axial flow rotor is a plate. 
     
     
         3 . The device of  claim 2 , characterized in that the plate is centered on the output shaft. 
     
     
         4 . The device of  claim 2 , characterized in that a deflector cone is centered on the plate. 
     
     
         5 . The device of  claim 2 , characterized in that a deflector prism is centered on the plate. 
     
     
         6 . The device of  claim 1 , characterized in that the surface area of the deflector placed below the axial flow rotor is extended to the area projected onto it by the stirring device. 
     
     
         7 . The device of  claim 1 , characterized in that the deflector ( 6 ) placed below the axial flow rotor consists of:
 a) a central plate; and   b) surface portions distributed angularly around the central circular plate and having a progressive profile diverging outwards and towards the bottom of the reactor.   
     
     
         8 . The device of  claim 7 , characterized in that the divergent progressive profile of the surface portions is able to be capable of bring about a Coanda effect on any flow surging tangentially in the section described by the divergent progressive profile. 
     
     
         9 . The device of  claim 8 , characterized in that a deflector cone is centered on the central plate. 
     
     
         10 . The device of  claim 1 , characterized in that:
 a) the gas injection device configured to be capable of introducing a gas above the axial flow rotor comprises:
 i) a self-aspirating turbine immersed in the reactor, placed above the axial flow rotor and which is capable of being driven by the output shaft; and 
 ii) a cylinder coaxially enveloping the output shaft, the lower end of which emerges in the turbine and the upper end of which is connected in a sealed manner to the drive device and is drilled with an opening adapted to receive an injection of a gas into an annular gap delimited by the shaft and the cylinder; and 
 iii) the self-aspirating turbine comprises two superimposed discs and an assembly of radial blades arranged between the discs and attached thereto, the upper disc being drilled with a central hole into which the lower end of the cylinder enters which delimits, with the edge of the said hole, a space that is at least partially annular, through which liquid is drawn into the self-aspirating turbine.