Modelling of the calculation of the power input for aerated single‐ and multistage impellers with special respect to scale‐up

For both laboratory and industrial scale fermenters the stirred fermenter is often being used. Especially for the design procedure of industrial fermenters with variable speed drive it is important to know the exact power characteristics for single and multiple impellers. The calculation procedure used for estimating the gassed power input gives the possibility to calculate the gassed power drawn by at maximum 3 impellers in vessels up to 3.5 m in diameter in aerated water. For calculation one only needs known parameters. This power input is valid for low and medium viscous fermentation broths too because especially after the addition of antifoam agents the properties of the liquid phase are then comparable to water as a coalescing liquid. It is possible to calculate the gassed power drawn by each impeller of a multiple system. This calculation procedure is applicable to different fermentation broths where in the range of low aeration rates the results differ from those for water.