Design/optimization of energy-saving extractive distillation process by combining preconcentration column and extractive distillation column. (2nd October 2015)

• Record Type: Journal Article
• Authors: An, Yi; Li, Weisong; Li, Ye; Huang, Shanyuan; Ma, Jian; Shen, Changlin; Xu, Chunjian
• Is Part Of: Chemical engineering science. Volume 135(2015)
• Page Start: 166
• Page End: 178
• Publication Date: 2015-10-02
• Subjects: Extractive distillation -- Energy-saving -- Process design; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2015.05.003
• Languages: English
• ISSNs: 0009-2509

Abstract

Abstract: In extractive distillation, the addition of entrainer may reverse the relative volatility of the feed components causing the component with higher-boiling point to be removed as the distillate from the extractive column. In this study, the energy saving possibility of a three-column extractive distillation system was studied when this phenomenon occurred. Based on a three-column conventional extractive distillation system, an innovative energy-saving extractive distillation process with lower capital investment was developed by combining preconcentration column and extractive distillation column. Two important case studies were investigated to verify the above-mentioned energy and economic advantages: the separation of n -propanol-water using N -methyl-2-pyrrolidone (NMP) as entrainer and the separation of ethyl acetate–ethanol using furfural as entrainer. In order to separate these two mixtures, first a three-column extractive distillation sequence including a preconcentration column was applied to diluted fresh feedstock. Then, based on this three-column conventional extractive distillation system, an innovative energy-saving distillation process was developed. For the two separated mixtures, based on the method of global economic optimization, a scheme with optimum design variables was developed for both of the conventional distillation and the new proposed distillation processes. Results revealed that the new process offered 22.76% and 17.25% energy-savings respectively. Similar percentage of reduction in total annual costs (TAC) can also be obtained when compared to the conventional distillation process. Graphical abstract: Path from conventional setup to energy-saving new process. Highlights: An innovative two-column extractive distillation process was developed. The new process is energy efficient with lower capital investment. Two systems were investigated to verify the energy and economic advantages.