Multistage high pressure mixer-settler system

An extraction apparatus has been developed for pressures up to 30 MPa and temperatures up to 120 degrees C, as an alternative to the counter-current column used in supercritical fluid extraction. The apparatus consists of five mixer-settler stages which are arranged in counter-current flow. Regenerative pumps are used as mixers to achieve an intense contact between the two phases and to create a large mass transfer surface area. Cyclones are used as separators to avoid back mixing. Previous work with a single stage module yielded a separation efficiency of about 96%. The achieved mass transfer surface area was 2'000 - 3'000 m(2)/m(3). The multistage apparatus is currently being tested. Results of separation efficiency and behaviour will therefore be presented at the sysmposium in October 1996.