Methodik zur simultanen Lösungsmittelauswahl und Dimensionierung von Extraktionskolonnen

RWTH Publications (RWTH Aachen)

Abstract

During development of extraction processes, a solvent is usually selected first based on simple criteria. Afterwards, the apparatus dimensions and operating conditions are optimized for this solvent and the solvent recovery is designed. This non-holistic approach for the solvent selection does not necessarily lead to the best overall result. In this work, a model-based methodology for the simultaneous solvent selection and dimensioning of extraction columns was therefore developed. The considered process consists of the extraction column and a solvent recovery by distillation. The optimum operating point and the required apparatus dimensions are determined individually for each solvent candidate in order to achieve the minimum overall costs. On the basis of these minimum total costs the most economical solvent is selected. Different modeling depths were considered in the developed methodology. They were compared with experimental data and evaluated with regard to the influence on the result of solvent selection and column dimensioning. First, it was shown that the consideration of fluid dynamic effects on the extraction efficiency is of great importance. In the next step, the influence of cross-solubilities between the phases was considered, which caused strong changes in the process design and thus also had an influence on the solvent selection. Finally, it was shown that the frequently used assumption of a monodispersion using the Sauter mean diameter has no significant disadvantages in this methodology compared to the more complex calculation based on a droplet size distribution. In summary, a novel methodology has been developed that enables important decisions, such as solvent selection, to be made at an early stage of process development based on a holistic consideration of the whole extraction process.

Authors 1

1. Jan Kampwerth corresponding Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen