Modelling of fractionation in a molecular evaporator with divided condenser

Fractionation in a one-stage film evaporator can only be done by draining the condensate from different heights of a divided condenser. We have shown the capabilities of this distillation in a short-path (molecular) evaporator with a falling liquid film in a model study, taking into account heat and mass transfer in both liquid films on the evaporating and condensing surfaces, and mass transfer in the vapour phase. The data on flows and compositions of fractions were obtained for a binary test mixture at various feed rates, feed compositions, evaporating and condensing temperatures, and at various condenser arrangements. This mode of short-path distillation in an evaporator with a divided condenser can be used for fractionation and in cases where recycling of some portion of distillate is required. The comparison of the experimental results with the model study results shows a satisfactory qualitative agreement between the experiment and the theory. (C) 2000 Elsevier Science S.A. All rights reserved.