Drop size and hold-up in countercurrent extraction with supercritical CO2 in a spray column

The drop size and hold-up were measured in a continuous countercurrent extr action spray column of 22.7 mm i.d. under near-critical and supercritical c onditions. The drop size was measured by analysis of images and hold-up by the shut-off method. The systems studied were 5 and 10 vol % 2-propanol + w ater and 10 vol % ethanol + water extracted with carbon dioxide, at tempera tures from 25 to 45 degreesC and pressures from 6.9 to 13.8 MPa. Data were correlated with physical properties of the system. The model developed to p redict the drop size agreed favorably with experimental data with an averag e absolute relative deviation (AARD) of 5.6%. In the case of hold-up, the A ARD was 12.4%.