Diffusional models of multicomponent distillation and their experimental verification

Abstract

In the present paper the equimolar, non-equimolar and simultaneous mass and heat transfer models of multicomponent distillation are developed and verified. The equations composing the models are based on the linearized diffusion theory and can be divided into three separate groups: (1) interfacial conditions describing the gas-liquid interface; (2) kinetic relations, which define the mass fluxes and whose general form results from the type of transfer assumed; (3) balance equations, associated with the model employed for a contact stage and determined by the fluxes previously estimated. The main purpose of the work was to develop the methods for calculating the mass fluxes for various types of diffusion occurring in distillation; hence, the quantitative basis for these methods was provided by the two first groups of relationships. The verification of the equimolar and non-equimolar models was carried out using the experimental results obtained by the authors for ternary distillation in a 0.25 m I.D. sieve-plate column and literature data for a bubble-cap column. The model for simultaneous mass and heat transfer was analysed only qualitatively. The calculations performed employing the various models differed only slightly from each other and agreed very well with the experimental findings.