POWER REQUIRED FOR UPPER AND LOWER IMPELLERS IN TURBULENT MIXING VESSELS WITH DUAL IMPELLERS

individual power required for the upper and lower impeller of a dual impeller in turbulent mixing vessels with nine types of dual impellers were measured. The following points were revealed. 1) The power of disk turbines (D) in dual configuration is 0.7-0.9 times that of a single one,the power of downward pumping pitched turbines (Pd) was 0.6-1.9 times that of a single one, and the power of upward pumping pitched turbines (Pu) was 0.6-1.3 times that of a single one. These behaviors of power are closely related with flow transitions. 2) In the range of impeller Spacing/Vessel diameter=1/6-1/4, for D (upper)-Pd (lower), Pu-D and Pu-Pd dual impellers, a downward pumping flow due to Pd becomes an upward flow, and an upward flow due to Pu becomes a downward flow.