4. Conclusions
The gas–liquid–liquid macro-mixing in a stirred vessel of standard geometry has been investigated with water as the continuous phase and three other immiscible liquids and air as the dispersed phases. The mixing time of the continuous phase and the power consumption have been determined by means of the electrical conductivity and shaft–torque techniques, respec- tively. The following findings are concluded:
(1) Generally, the trend for the mixing time in the gas–liquid– liquid system is similar to that in a liquid–liquid system. In turbulent stirred reactors, the aeration does not change the influencing trend of injector and probe positions, impeller type, impeller clearance and agitation speed, etc., as com- pared with corresponding liquid–liquid systems.
(2) Gas aeration damps the macro-mixing process of the contin- uous phase at low aeration rates, and enhances the mixing efficiency at higher gas flow rates. Contrary to the gas effect, the dispersed oil phase increases the macro-mixing intensity at low holdups and decreases the macro-mixing intensity of the continuous phase at higher holdups.