Processes with supercritical fluids are known for both solid and liquid mat
erials. Liquids are typically brought into contact with the supercritical f
luid in countercurrent columns. In recent years, high-pressure spraying pro
cesses such as the spray extraction of viscous media have been investigated
. The central idea is to improve mass transfer by dispersing the liquid pha
se in the supercritical phase. A mixer-settler system is investigated for t
he regeneration of caffeine-loaded CO2 at various conditions. Water is spra
yed into the CO2 flow and the resulting two-phase flow passes through a sta
tic mixer to intensify phase contact and prevent coalescence of the water p
hase. The system shows an efficiency of 80-90% in comparison with the theor
etical maximum based on ternary equilibrium data from the literature. The p
ressure loss of the static mixer (Kenics) is determined experimentally for
various conditions. The pressure drop of the two-phase Bow depends on CO2 v
elocity and is significantly determined by the mass ratio. It does not exce
ed 2500 Pa in the present investigations, and can be neglected in supercrit
ical fluid plant design. (C) 1999 Elsevier Science B.V. All rights reserved
.