International Society for Industrial Process Tomography

Applicability of ERT for the identification of flow regimes and mixing time in gas-liquid stirred tanks

A. Zak¹, T. Moucha¹, F. Maluta², G. Montante², A. Paglianti^3*

¹Chemical Engineering Department, University of Chemistry and Technology Prague, Czech Republic

²Department of Industrial Chemistry ‘Toso Montanari’, University of Bologna, Italy

³Department of Civil, Chemical, Environmental and Material Engineering, University of Bologna, Italy

^*Email: alessandro.paglianti@unibo.it

ABSTRACT

In this work, a gas-liquid high aspect ratio tank stirred with multiple Rushton turbines is investigated by Electrical Resistance Tomography. The main goal of the study is to analyse the homogenization dynamics of a liquid tracer and the spatial distribution of the gas phase obtained from the conductivity measurements under transient and steady state conditions for the identification of the mixing time and the gas-liquid flow regimes in stirred (bio-)chemical reactors. The analysis is carried out adopting a pilot stirred tank of geometry resembling typical industrial fermenters under variable gas flow rates and impeller speeds, thus covering different gas-liquid regimes and gas–impeller interactions. Data collected with vertical and horizontal arrangements of the electrodes confirm that the ERT technique provides sound results for gaining insight into the gas-liquid flow dynamics under optically inaccessible conditions.

Keywords: Stirred tank, Flow regimes, Gas-liquid, ERT, Mixing time

Industrial Application: Biotechnology, Chemical engineering, Pharmaceutical engineering.