Fluid dynamics and power consumptions in a single use stirred tank adopted in the pharmaceutical industry

Single use bioreactors (SUB) are recurrently adopted within the pharmaceutical industry since they offer several advantages with respect to traditional bioreactors. Generally, they consist of a stainless-steel container with a bag and an integrated impeller for handling (mixing stage), storage (post mixing stage I) and transfer (post mixing stage II) of formulated products. In this work, one of the single use bioreactor types, the Flexel-Levmixer by Sartorius, is investigated. It is a vessel with a square section stirred with a bottom impeller, for which little information is available in the literature, thus making troubleshooting and optimization difficult. To address this issue, a combination of experimental techniques, namely Particle Image Velocimetry, and torque sensors based on strain gauges, are selected for the investigation aimed at the understanding of the fluid dynamics and power consumption with different filling levels and impeller speeds.