Identification of a continuous supercritical carbon dioxide extraction process

Abstract

Number of different industries are searching for more cleaner alternative extraction processes. An alternative showing the most promise is the supercritical fluid extraction (SFE). The main advantage of SFE is the ability to use carbon dioxide as a safe and clean solvent. This benefit has been proven in the food and pharmaceutical industries, but the lack of industrial scale continuous SFE-processes have prevented it from becoming more prominent. Proof of safe and stable operation of a process usually has been the solution for scale up. The objective of this study was to identify process models of a newly developed continuous SFE-process.

Central composite design (CCD) was realized to acquire data from process temperature, energy consumption and yield for identifying a pilot-scale continuous supercritical carbon dioxide extraction process. Additionally, some preliminary performance comparisons were made between continuous and batch operation of the considered process.

The identified models showed good agreement with the experimental data as correlation coefficients ranged between 0.83 to 0.99. The continuous and batch process comparison showed differences in average electricity consumption, 10%, and average yield, 60%, favouring the continuous process in case of isopropyl alcohol (IPA) extraction.

The energy consumption and yield models from this study could be used to optimise the process conditions of the considered process. The process temperature model could be used to develop a model-based temperature controller. The results of this study indicate the potential benefits of further development and research of continuous SFE-processes.