Axial Dispersion in a Pulsed and Nonpulsed Disc and Doughnut Solvent Extraction Column

In solvent extraction columns mechanical agitation is usually introduced to improve the extraction efficiency. However, some industrial columns have been found to have higher extraction efficiency while running with no pulsation. In this study, axial dispersion coefficients in the continuous phase were measured under pulsing and nonpulsing conditions using a 72.5 mm diameter disc and doughnut solvent extraction column. The axial dispersion coefficients were measured using the unsteady tracer injection method. Under nonpulsing conditions, the axial dispersion coefficient increased with increasing continuous phase velocity, but it did not change significantly with the increase of the dispersed phase velocity. With increasing pulsation intensity, the axial dispersion coefficient increased. A correlation is proposed to predict the continuous phase axial dispersion coefficient in a pulsing and nonpulsing disc and doughnut solvent extraction column.