Scale-Up of Fermenter

Abstract

Fermenter scale-up methods based on industrial manufactured records and numerical flow simulation will be introduced. Firstly, we have surveyed basic specifications of 480 industrial fermenters, and obtained standard specifications and their correlations with the fermenter scales. Subsequently, we have investigated recent computerized fluid dynamics, CFD, and applied it to fermenter performance descriptions and compared the results to actual manufactured records and common empirical equations for clarifying the CFD applicability to fermenter scale-up design. For simulation methods, the k-ε model, the dynamical multi-block method and the drift flux model have been used. Comparing with manufactured records and empirical equations, CFD has given the same qualitative trends in the following phenomena. By keeping a gas flow rate constant, increasing a tank aspect ratio gives higher gas hold up; lower power input decreases gas-holdup and insufficient gas bubble circulation under the bottom impeller; flow interference and a power consumption drop are caused by narrow spaced impellers; a larger impeller diameter gives lower local shear stress along with higher impeller flow rate and average shear stress. Finally, fermenter scale-up design guidelines based on manufactured results and CFD have been proposed.