Process Design And Simulation Of Sulfolane Wastewater Treatment

The recovery of organic wastewater can reduce environmental pollution and save resources,which is an important component in industrial wastewater treatment.Multi-effect evaporation process is commonly used to treat the sulfolane wastewater from polyarylether resin polymerization process in industry.But the energy consumption was high,the treated water and sulfolane could not be recycling.The extraction-distillation hybrid process and extraction-(four-effect evaporation)hybrid process are developed to treat sulfolane wastewater.A suitable solvent is found through solvent screening,the processes are simulated by Aspen plus,and compared with four-effect evaporation process.It was screened by empirical analysis of the low boiling point solvent with solubility,toxicity,chemical stability,economy and other factors.The polarity parameters of the screened solvent were calculated according to the molecular connectivity index method for re-screening.Single-stage extraction simulation was carried out with the selected solvent,and dichloromethane was selected as the solvent.The extraction-distillation hybrid process was optimized by Aspen plus with dichloromethane as solvent and NRTL activity coefficient model.The sensitivity analysis tools were used to optimize the parameters of extraction column and distillation column.The effects of operating temperature,solvent ratio,number of equilibrium stages of extraction column,and the number of theoretical stages,reflux ratio,feed stage and distillation to feed ratio of distillation column were studied.The simulation results indicated that the recovery and mass fraction of sulfolane are 99.95% and 98.31%,respectively.The mass fraction of treated water is 98.96%,and the sulfolane concentration of the wastewater is 34 mg/L.The heat duty is about 15228 kW.The extraction-(four-effect evaporation)hybrid process was optimized by Aspen plus,The extraction column conditions were the same as extraction-distillation hybrid process,and the usage of heating steam was 8057 kg/h.The simulation results showed that the recovery and mass fraction of sulfolane are 95.91% and 96.84%,respectively.The mass fraction of treated water is 98.42%.The heat duty is about 4844 kW.The extraction-distillation hybrid process,extraction-(four-effect evaporation)hybrid process and four-effect evaporation process were compared.The heat duty of the four-effect evaporation process is about 24078 kW,the mass fraction of sulfolane in treated water is 1.09%,the recovery and mass fraction of sulfolane are 89.98% and 97.76%,respectively.The heat duty of the extraction-distillation hybrid process is about 15228 kW,which is reduced by 37% than four-effect evaporation process,and the treated water and sulfolane can be recycled.The heat duty of the extraction-(four-effect evaporation)hybrid process is about 4844 kW,which is reduced by 80% than four-effect evaporation process,the recovery of sulfolane is improved but the purity is lower.The extraction-distillation hybrid process is the preferential selection.