Axial dispersion in an air-pulsed extraction column

Abstract

Axial dispersion coefficients have been measured in the continuous phase of a 10.8cm diameter pulsed plate extraction column. The measurements were made by observing the course of an instaneous chemical reaction between acid and base in the continuous phase, using phenolphthalein as indicator. Two different plates were imployed, namely perforated and star-shaped plates. The air pulsing is carried out by means of solenoid valves and a timing controller. The pulsation amplitude and frequency were varied from 0.5 to 8.0 cm and from 0.5 to 2.0 Hz, respectively. Axial dispersion coefficient increased with increasing amplitude and frequency of pulsation, with decreasing free opening fraction of the plate and plate spacing distance. The flow velocities of each phase and the plate thickness have no significant effects on the axial dispersion. The data have been correlated in terms of amplitude, frequency, plate spacing, plate free area.