Improving oxygen transfer efficiency by developing a novel energy-saving impeller

Radial flow impeller is the energy-intensive and fundamental component in reactors for the gas-liquid transfer process. A newly designed fan-shaped turbine (FT) assembly with annular-sector-shaped concave blades was characterized and compared with the Rushton turbine (RT) and Bakker turbine (BT). A new surface equation was established to design the blade of the FT impeller. Under turbulence conditions, the FT impeller showed a lower power number and higher relative power demand (RPD) compared with RT and BT impellers. The power number of the FT impeller was 1.7, lower by 26% than that of BT impeller. The RPD of the FT impeller was nearly 0.95 at a high impeller speed. The critical dispersion speed, gas holdup, and volumetric oxygen transfer coefficient of the FT impeller were close to those of BT impeller. Moreover, the oxygen transfer efficiency of the FT impeller was remarkably higher by 35%-66% and 23%-34% than that of RT and BT impellers, respectively. The FT impeller showed competence in a broad operation range, strong robustness, energy-saving feature, and efficient mass transfer characteristics. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.