Target localization optimization of a superstructure triple-column extractive distillation with four-parallel evaporator organic Rankine cycles system based on advanced exergy analysis

The energy analysis and optimization of process system aiming to solve the problems of high consumption, low efficiency and unreasonable use of energy in the process of energy utilization has been widely researched and developed in recent decades. In this work, advanced exergy analysis was carried out for the triple-column extractive distillation (TCED) process separating ternary azeotropic mixture of ACN/EtOH/H2O. The total exergy destruction is 1097.69 KW. The avoidable exergy destruction, is 29.20%, mainly caused by the cooler and three condensers. Based on the thermodynamic analysis results, a superstructure TCED with four-parallel evaporator organic Rankine cycles (FPE-ORC) system is proposed, four working fluids were selected. An improved genetic algorithm is used to obtain the optimal operating parameters of the ORC system by using the exergy efficiency and annual net profit (ANP) of the ORC as two conflict objective functions. Compare with existing process, the FPE-ORC system with working fluid R600 provides the highest exergy efficiency of 12.27%, with working fluid R600a leads to the best economic benefit of 6.43 E + 4 dollar/year.