![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
Abstract
Design of counter-current liquid-liquid extractors is considered on the basis of a differential model. Four extraction systems with different column types are used to illustrate the procedure. The estimation of the column diameter generally involves iteration. Once this is fixed, specific throughputs become known and the values of the operating variables, namely, drop size, dispersed-phase holdup, mass-transfer coefficients, and continuous phase axial-mixing coefficient are calculated from explicit empirical equations which are now available in the literature. Reliable data for dispersed-phase axial mixing are not always available, but it is shown that the column heights calculated by setting the Peclet number of the dispersed phase equal to that of the continuous phase are comparable to those obtained using literature correlations. The effect of the value of the dispersed-phase mixing coefficient on the column height is given. Furthermore, the variation in the column height and diameter with fractional flooding is also investigated. The method presents a quick and reliable procedure and is also applicable when the equilibrium line is curved. At worst, the column heights predicted provide first estimates for more sophisticated calculations which could be carried out if additional data were available.