Improved Modeling of Bubble Column Reactors by Considering the Bubble Size Distribution

Abstract

Bioconversion of glucose to gluconic acid with glucose oxidase as enzyme was considered to occur in a bubble column reactor at 40 °C, atmospheric pressure, and pH 5.5 while oxygen gas velocity was varied in the homogeneous and transition regime in the range of 0.0014–0.0112 m s–1. It was found that the superficial gas velocity has a positive effect on gas holdup, mean bubble size, and volumetric mass transfer coefficient, while the glucose concentration has a negative influence on these hydrodynamic parameters. The modeling of bubble column by considering the complete bubble size distribution in the governing equations was carried out in this work. The model was also solved by considering the single and double sizes of bubbles instead of complete bubble size distribution. It was shown that the results of the model, considering the complete bubble size distribution, is in a good agreement with the experimental data, while the considered single and double bubble sizes cannot predict the experimental data of oxygen concentration in the reactor properly. It was also found that the superficial gas velocity has a positive influence on oxygen concentration while glucose concentration has negative influence at low superficial gas velocity and positive influence at high gas velocity.