Enhanced process design and performance evaluation of reactive extractive distillation based on dual-evaporator parallel organic Rankine cycle coupled with heat integration technology

In this study, acetonitrile and ethyl acetate organic wastewater produced in the production process of cefixime were taken as the research object, and a new process scheme was proposed. The double evaporator parallel organic Rankine cycle was combined with heat-integrated assisted reactive extractive distillation technology. Through toxicity evaluation, relative volatility analysis, and molecular surface electrostatic potential calculation, ethylene glycol was selected as the optimal extractant. On this basis, the non-dominated sorting genetic algorithm II was used to optimize the parameters of the three basic processes with the total annual cost and total gas emission as the optimization objectives. Finally, the double-column reactive extractive distillation was determined as the optimal basic process. Three gradually enhanced energy-saving schemes are further constructed and systematically evaluated: heat integration, heat pump synergistic heat integration, and dual evaporator organic Rankine cycle coupled heat integration process. The results show that the double evaporator parallel organic Rankine cycle coupled with heat integration assisted reactive extractive distillation process has the best comprehensive performance. Compared with the optimal benchmark process, the total annual cost is reduced by 29.22 %, the total gas emission is reduced by 35.46 %, and the total energy consumption of the system is reduced by 39.86 %. This study provides a feasible technical path for the efficient resource treatment of pharmaceutical wastewater and has important reference value for promoting the green and sustainable development of the pharmaceutical industry.