Patent ID: 7431272

Claim:
An apparatus which may be used for stirring and injecting a gas into a liquid located in a container, wherein said apparatus comprises: a) a reactor, wherein said reactor contains a liquid; b) a drive device located above said reactor, wherein: 1) said drive device comprises a vertical output shaft; 2) said output shaft comprises at least one axial-flow moving assembly; and 3) said axial-flow moving assembly is: i) located at a lower end of said output shaft; and ii) substantially submerged in said fluid; c) a cylinder located around said output shaft, wherein: 1) said cylinder comprises both an upper and a lower cylinder end; and 2) said upper cylinder end: i) is substantially sealed to said drive device; and ii) comprises an opening for injecting a gas into an annular gap between said output shaft and said cylinder; d) a self-priming impeller, wherein: 1) said impeller is submerged in said liquid and is capable of being driven by said output shaft; and 2) said impeller comprises: i) a substantially planar upper disk, wherein: aa) said upper disk is perforated with a central hole; bb) the edge of said central hole and said lower cylinder end form an at least partially annular space; and cc) said liquid is sucked into said impeller through said annular space; ii) a lower disk, wherein the surface area of said lower disk is less than the surface area of said upper disk; and iii) a set of radial vanes located between, and attached to, said upper and said lower disks; and e) a direction means for directing a gas/liquid dispersion expelled radially from said impeller toward said axial-flow moving assembly, wherein said lower disk is at least partially cut out.