Separation of azeotropes in batch extractive stripper with intermediate entrainer Viktoria Varga a,c , Erika R. Frits a,b , Vincent Gerbaud c , Zsolt Fonyo b , Xavier Joulia c , Zoltan Lelkes a , Endre Rev a,b a Budapest Univ. Techn. Econ., Dept. Chem. Eng. ,and b Hung. Acad. Sci., Res. Group Techn. Chem.; Muegyetem rkp3, Budapest H-1111, Hungary c INPT, Lab Genie Chim, 118 route de Narbonne, Toulouse F-31062, France Abstract Batch extractive distillation is an attractive technique for separating azeotropic mixtures (Steger et al 2005). These processes can be carried out in a batch rectifier, and in a stripping column, as well; but, unfortunately, the necessary feasibility studies of the latter one are still missing from the scientific communications. Here we present the first preliminary results on the feasibility of separating azeotropes with intermediate boiling entrainer in batch extractive stripper. The following mixtures are studied here: 1: methanol (MeOH) / toluene (TOL) (minimum boiling azeotrope) with triethylamine (Et 3 N) as intermediate boiling entrainer; 2: chloroform (CHCl 3 ) / ethyl acetate (EtOAc) (maximum boiling azeotrope) with 2-chlorobutane (2ClBu) as intermediate boiling entrainer. Separation of the same mixtures with the same entrainers in rectifier have already been studied (Lelkes et al., 2002, Varga, 2003); thus, the results of the present feasibility study allow comparing the separation processes in a stripper or in a rectifier for the selected specified mixtures. Similar mixtures occure in Rev et al., 2003. The mixture to be separated is charged to the reflux drum (the so-called vessel, or still vessel), of great hold-up capacity. Liquid entrainer is added to the stripping unit for enhancing the relative volatility of the mixture. The boiler at the bottom of the column serves as to evaporate the liquid. The product is removed from the bottom. The entrainer is either premixed to the charge (Solvent-enhanced Batch Stripping, SBS), or it can be continuously fed to the system (Batch Extractive Stripping, BES). The place of the continuous feeding can be the top vessel (BES-T), or some intermediate point in the column (BES-I). Keywords: Extractive distillation, batch stripper, profiles maps 1. Methodology A feasibility method for studying batch extractive stripping is developed on the basis of the profiles maps analysis (Lelkes et al, 1998). The column concentration profile can be modelled with the differential equation ( ) * d d y y x - = L V h (1) where h is dimensionless column height; V and L are vapor and liquid flow rates, respectively; y* is vapor composition in equilibrium with the liquid composition x; and y is the actual vapor composition according to the component balance. The extractive profile is computed top down; the stripping profile is computed bottom up. and 9th International Symposium on Process Systems Engineering W. Marquardt, C. Pantelides (Editors) © 2006 Published by Elsevier B.V. 16th European Symposium on Computer Aided Process Engineering 793