Hydrodynamics of gas phase under typical industrial gassing rates in a gas-liquid stirred tank using intrusive image-based method

The intrusive image-based method is used to probe local gas hydrodynamics, bubble size (BSD) and holdup distributions (BHD) in a gas-liquid stirred tank reactor (STR). A distinctive scheme combining automatic and manual processes is implemented to identify the object bubbles in the images. This method shows more accurate for judging the flow regime in gas-liquid STRs. Because of high intensity turbulence therein, the instantaneous local gas-liquid flow may present several very different patterns though the time-averaged bulk flow is homogeneous. More small bubbles are detected because of high resolution of the instrument, and consequently d(32) obtained is smaller than those by other methods. The BSD and BHD at moderate gassing rates are reported and found closer to the physical reality. The measurements are of significance to understanding the fluid mechanics and provide benchmark data for the validation of the mathematical models in the gas-liquid STRs operating at industrial conditions. (C) 2020 Elsevier Ltd. All rights reserved.