Triple Column Pressure-Swing Distillation for Ternary Mixture of Methyl Ethyl Ketone /Isopropanol /Ethanol

Abstract

Methyl ethyl ketone (MEK), isopropanol (IPA), and ethanol (EtOH) are important chemical materials and widely used as intermediates solvent in many chemical processes. The boiling points of three pure components are very close and the maximum temperature difference is 3.74 K. Under atmospheric and high pressures, the MEK /IPA /EtOH mixture forms two binary pressure-sensitive azeotropes of MEK-IPA and MEK-EtOH and its residue curve maps (RCMs) present one distillation boundary. Under 0.1 atm, the azeotrope of MEK-IPA disappeared and the MEK /IPA /EtOH mixture forms one azeotrope of MEK-EtOH. According to the RCMs, two different separation sequences using triple column pressure-swing distillation (TCPSD) were available for the separation of this ternary mixture. Vapor-liquid equilibrium data from the literature were regressed to verify the reliability of the thermodynamic model used. Several operating parameters were optimized on the basis of minimum total annual cost (TAC) to study the effect of separation sequence and heat integration on the economy of TCPSD. The results show that the IPA-MEK-EtOH separation sequence is more economical and partial heat integration with this sequence has great economic advantage over full heat integration. The choice of separation sequence and heat integration should be considered for separating this type of mixture from the perspective of TAC.