Designing Extraction Columns for Fractional Liquid-Liquid Extraction

Often times a simple liquid-liquid extraction process (single counter current solvent) will not work effectively for certain separations due to mutual extraction of a number of components into the solvent phase. Many of these separations are ideal candidates for an under utilized technique known as fractional extraction. Like simple extraction, the best method for designing an extraction column for a fractional extraction process is via pilot plant testing followed by scale up from the pilot data. This report demonstrates this method of design using two different separation applications. One application involves the separation of a mixed polymer feed.  The second one is a heavy naphtha feed that is separated into polar aromatics and non-aromatic impurities. Pilot plant equipment set-ups are presented along with the test procedures used to optimize the performance for both applications. Scale up to the production columns are discussed.