GAS-LIQUID MIXING STUDIES - A COMPARISON OF RUSHTON TURBINES WITH SOME MODERN IMPELLERS

Based on the literature, a comparison of the Rushton turbine with othe r impellers, many of them modern commercial developments, is made. Thi s comparison shows that there are many impellers available, some radia l and some axial, which eliminate many of the weaknesses associated wi th the Rushton though some weaknesses remain or others are introduced. Based on this analysis, a new axial flow hydrofoil impeller, the APV- B2, has been designed and some preliminary results are also reported h ere. It has a low ungassed power number so that a relatively low torqu e is required to drive it when using it with a large impeller-to-tank diameter ratio. This large diameter also enables greater volumes of ga s to be handled without flooding at similar energy dissipation rates. In the downward pumping mode, torque fluctuations found with such a mo de of operation are less than with other axial flow hydrofoils, and in the upward pumping mode they are essentially eliminated. This latter mode, as with pitched blade turbines, is also extremely effective at g as dispersion and at a specific ungassed power input of 1 kW m-(3), a typical industrial value, the power reduction on gassing is negligible .