THE USE OF UPWARD PUMPING 45-DEGREES PITCHED BLADE TURBINE IMPELLERS IN 3-PHASE REACTORS

Earlier work on a range of geometries showed that an upward pumping six-blade 45°-pitch agitator (6MFU) of impeller to tank diameter ratio equal to one half with a sparger of about 0.8 the impeller diameter was the most versatile for solid suspension, gas dispersion and a combination of the two even at gas rates up to 3.5 vvm in low-viscosity liquids. That work also showed that at the same specific power input and superficial gas velocity approximately equal hold-ups were achieved even at different scales. Here it is shown that, by using such 6MFU-sparger combinations, kLa values comparable with those of Rushton impellers are also obtained. It is concluded that, because of its superior hydrodynamic versatility and comparable mass transfer performance, overall this geometry offers the best operating characteristics amongst the geometries tested. © 1990.