TURBULENT-FLOW IN MECHANICAL STIRRED VESSELS WITH MULTIPLE IMPELLER .3. BUBBLE MOTION IN PLANT-SCALE MULTIPLE IMPELLER STIRRED TANKS

To examine the behavior of bubbles in plant scale multiple impeller st irred vessels, the motion of bubbles is simulated by coupling the calc ulated flow field, The results showed that the volume fraction of gas passing through the middle and the upper impellers were 30-40% of the original gas fed to the system, This result is in good agreement with the previous bench scale data, This model was extended to investigate the uniformity of power consumption in the plant scale agitated vessel with triple impellers. The ratio of the power consumptions of the mid dle to the lower impellers was 2.03, and that of the upper to the lowe r impellers was 1.82. This result implied that non-uniform power consu mption as seen in a bench scale vessel also exists in a plant scale ve ssel, and thus must be taken into consideration in the design of large scale stirred vessels.