Power consumption and oxygen transfer optimization for C5 sugar acid production in a gas-liquid stirred tank bioreactor using CFD-Taguchi method

Abstract

Power consumption and oxygen transfer are considered the two most important direct indexes, affecting the effective and cost-efficient C5 sugar acid fermentation from C5 sugar. In this work, an effective optimization approach combining computational fluid dynamics (CFD) modeling and the Taguchi method, was presented to evaluate C5 sugar acid fermentation in a gas-liquid stirred tank bioreactor. Three most critical control factors of impeller type (Rushton turbine (RT), concaved blade disc turbine (CBDT), and four wide-blade hydrofoil impeller pumping down (WHd)), agitation speed and aeration rate involved three levels, were quantitatively studied by numerical simulation based on a validated CFD model. Results indicated that, the WHd impeller gave the best energy-saving performance, the CBDT impeller gave the best oxygen transfer performance, while the RT impeller was the most balanced one. The agitation speed contributed most to both the power consumption and oxygen transfer, while exerting minor impact on compromise indexes. The aeration rate had little contribution to power consumption and oxygen transfer, while deserving more attention when energy efficiency and trade-off optimization are considered. These findings can be used as guidelines to achieve efficient and economical C5 sugar acid production.