Optimal design framework and techno-economic-environmental assessment for efficient solvent recovery separation of ethyl acetate and methanol

Abstract Pharmaceutical solvent recovery processes cause tremendous fossil energy consumption and pollutant emission. In order to search highly efficient separating processes, a novel optimization framework is developed for the solvent recovery industry. Take an important solvent recovery process of the ethyl acetate and methanol separation as case study, dimethyl sulfoxide and glycerol are firstly screened as optimal extractants for two different sequences. Through multi-parameters coordinated optimization, the total annual cost, energy consumption, and CO2 emission of the first case are 282.0 k$/y, 642.6 kW, and 1956 t/y, 37.2%, 35.9%, and 50.0% lower than that of the second case. A response surface methodology is then used to further optimize the operating parameters of the first case with minimum total annual cost as objective function. Through integrating multi-parameter coordinated optimization and response surface methodology, the optimal total annual cost is found to be only 264.6 k$/y with product purities above 99.8 wt.%, and the optimal operating factors are number of stages of 50 and 12, reflux ratios of 1.236 and 0.401, extractant/feedstock ratio of 3.6 for the extractive tower and recovery tower, respectively. The corresponding energy consumption and CO2 emission of the first case are further decreased to 574.0 kW and 1749 t/y, 10.7% and 10.6% lower than that of preliminary optimization results. It is concluded that the proposed strategy will have application prospect for improving the techno-economic-environmental performance of the relevant processes.