Gas-liquid dispersion in a stirred tank with diferent impeller combinations

Power demand and gas holdup were studied in a stirred tank of 0.476?m diameter with different impeller combinations.Three types of impeller combination named radial flow impeller combinations consisting multiple curved disk turbines(CDT),axial flow impeller combinations consisting multiple 4-wide-blade hydrofoil impellers(WH) and mixed flow impeller combinations consisting half elliptical disk turbine(HEDT) and 3-narrow-blade hydrofoil impellers(CBY),were used in the experiments.The gassed power demand and the gas holdup correlations for different impeller combinations were obtained by regressing the experimental data. The results show that the mixed flow impeller combinations have the highest relative power demand(RPD) and the next is the axial flow impeller combinations.Under the same gassed power input,when the gas flow rate is lower,the gas holdup of the axial flow impeller combinations is the highest and when it is higher the gas holdup of the mixed flow impeller combinations is similar to that of the radial flow impeller combinations,and both are significantly that of the axial flow impeller combinations.The results are of importance to the design of the industrial multi-impeller gas-liquid stirred tank/reactors.