Energy efficient design through structural variations of complex heat-integrated azeotropic distillation of acetone-chloroform-water system

Abstract

This study presents enhanced energy savings through structural variations of a heat-integrated distillation column for the separation of ternary azeotropic mixture. The conventional sequence has a decanter followed by pressure-swing distillation (PSD) columns for separating acetone-chloroform-water azeotropic mixture. Based on a significant temperature gradient of the PSD, a double annular column was proposed in order that the heat from hot fluid to cold fluid passed through the shared column wall. The heat transferred to the stages near the reboiler could replace the use of external utility, thereby reducing the total energy consumption of the process. For accurate calculations of heat transfer rate, the trays with the double annular structure were simulated by computational fluid dynamics. However, the energy saving was not effective since the structure could not afford to utilize all the heat transferred and additional energy was required to recover. The newly proposed (partial double annular) structure transferred heat from a high-pressure column to two low-pressure columns. It demonstrated 7,807.78 kW of the theoretical energy saving which was almost double of the heat transfer amount. Consequently, the total utility consumption and total annual cost was reduced by 21.79% and 11.32%, respectively, compared to the conventional sequence.