Rigorous Modelling and Simulation of the Mass transfer on the Trays of a Pilot Scale Distillation column

Abstract

Distillation is a well-known separation process, which takes advantage on the differences on the relative volatilities of the components of a given mixture. Separation occurs on either trayed or packed towers, where simultaneous mass and heat transfer occurs. One of the mathematical models used to represent the phenomena occurring in distillation is the rate-based model. Opposite to the equilibrium model, the rate-based model avoids the use of efficiencies and computes mass and heat transfer rates. One of the most important requirements of the rate-based model is an adequate mass transfer model, whose structure depends on the kind of mixture and the trays/packing geometry. In this work, a mass transfer model is proposed for the sieve trays on a pilot scale batch distillation column. In this column, a mixture of 50 mol% methanol and 50 mol% ethanol is separated. The column used in this work has four trays, a total condenser and a pot. The operation regime of the column is bubbling. The whole rate-based model of the column is solved using Matlab R2013a, and the composition and temperature profiles are obtained. The results indicate that rate-based model with the proposed mass transfer model has a mean decrease of 7% in the error for the compositions, in comparison with previously reported approaches.