Power Consumption of “EGSTAR” Agitator under Aeration

Abstract

Power consumption in an agitated vessel with an “EGSTAR” agitator, which has been practically used as a bioreactor, was measured under aeration. The power consumption of the “EGSTAR” agitator did not decrease so much with aeration, in contrast to the result of a disk turbine impeller. In the turbulent flow region of Red>300, the power number at a specified gas flow rate takes a maximum value. The correlations of the maximum power number Npg, R and the rotational speed NR at which the power number takes the maximum are derived using both operating conditions and impeller dimensions.
The power number under aeration Npg in the range of N/NR>1 in turbulent flow region is correlated with the rotational speed N, with help of NR and Np_g, R, as
Np/Np_g, R= (N/NR) -0.30
The combination of the correlation of Npg above with the correlations of Npg, R and NR gives rise to the following power correlation of EGSTAR agitator under aeration.
Npg=0.68NA^-0.08
Fr^-0.19
(hd/d) ^0.01
(1-ε) ^0.22
Np, ^R
The power consumption of EGSTAR agitator under aeration is not affected so much by gas flow rate, in contrast to the result of a disk turbine impeller.