Characterization of the Dynamic Behavior of a Stirred Liquid–Liquid System for Process Control

Abstract

The dynamic behavior of a toluene/NaOH solution system was studied in a batch stirred tank. Characterization by step response experiments showed that the drop size response to stirrer speed steps behaves as a first-order system, whereas the stirrer speed responds as a second-order system. The respective time constants differed by at least one order of magnitude, suggesting effective control of the drop size is feasible by adjusting the stirrer speed. Based on experimental data, simple, linear system models were derived for the mean drop diameter and the interfacial area using the stirrer speed as input variable. Validation experiments showed good model qualities of about 70 % and the design of test trajectories proved the model's usability in an open-loop control.