The mathematical description of two‐phase separation processes

Abstract

AbstractIt was shown by Cohen, that for a large number of separation methods the multiplication of the elementary effect by means of a column or a cascade may be described by one basic column equation.In Cohen's treatment of two phase separation processes like distillation and chemical exchange, however, the axial dispersion effects have been neglected. Unfortunately the axial mixing may be rather large in two phase processes, especially when packed columns are applied.In this paper an improved derivation of the column equation for two phase processes is given. In this column equation the axial dispersion effects are included.The derivation starts from a mass balance holding for the entire cross‐section of the column. Into this mass balance the contribution of the interfacial mass transfer to the concentration distribution is introduced. In order to avoid superfluous mathematics the equation representing the interfacial mass transfer is simplified. As a consequence the application of the column equation derived is limited to systems of very closely related compounds like isotopes. Although the adverse effect of the axial dispersion on the separation results cannot yet be calculated, the theory presented may give good guidance, when investigating the conditions for obtaining optimal separations.