Simulation of Extractive Distillation for Recycling Tetrahydrofuran from Pharmaceutical Wastewater with Chem CAD Software

The functions and application of ChemCAD simulation software was introduced. Mathematical model of extraction distillation process was established. The extractive distillation process for preparation of tetrahydrofuran (THF) was simulated by SCDS rectification model in ChemCAD software, methanol-THF-solution and ethanedol-lithium chloride solution as extractant. Influence of extraction agent on vapor-liquid equilibrium curve of methanol-THF system and effects of theoretical plate number, feed and extractant input positions, extraction agent ratio (m(chlorinated lithium): v(ethanediol)), extractant ratio (m (extractant): m(feed)) and reflux ratio on tower top mass fraction of THF were investigated. The results of simulation were compared with experimental data. Under optimum extraction distillation conditions: theoretical plate 30, extractant plate 6, feed plate 18, extraction agent ratio 0.24g/mL, extractant ratio 2.7 and reflux ratio 5.0, mass fraction of THF on tower top can reach 97.2%. The distribution characteristic parameters of the column were simulated. The results of simulation and experimental data agree satisfactorily.