Simulation And Optimization Of Extractive Distillation And CO₂ Capture Process Based On Green Solvents

Distillation and absorption are the most commonly used separation processes in petrochemical industry.It will bring enormous environmental and economic benefits to the society,if separation efficiency can be improved and energy consumption can be reduced.The emergence of new designable low transition temperature mixtures（LTTMs）and ionic liquids（ILs）makes it possible to improve separation efficiency.Dividing-wall column,as a typical process intensification technology,has great potential in reducing energy consumption and capital investment.In view of this point,the extractive distillation of ethanol-water,ethyl acetate-ethanol-water and the CO2 absorption process with LTTMs and ILs as solvent are performed in order to achieve high separation efficiency in this paper,and the content is shown as follows:Firstly,glycerol,ILs[EMIM][BF4]and LTTMs ChCl/Urea（1:2）is used as entrainer in the extractive distillation process of ethanol-water,and the three processes are optimized by multi-objective genetic algorithm.The results show that the process using ChCl/Urea（1:2）as solvent is better than that using glycerol and[EMIM][BF4]as solvent in respect of total annual cost（TAC）,the CO2 emission（ECO₂）and extraction efficiency（Eext）.The TAC of process using ChCl/Urea（1:2）as entrainer is 4.65%and 7.25%lower than that with glycerol and[EMIM][BF4]as solvent,respectively.Then,the extractive distillation process of ethyl acetate-ethanol-water with[BMIM][OAC]as entrainer is simulated and optimized by using conventional process,solvent separation process and DWC process,respectively.The results show that the DWC process has the lowest TAC and ECO₂,but its thermodynamic efficiency is lower than that of conventional process and solvent separation process.Compared with conventional process and solvent separation process,the TAC of DWC process decreases by2.97%and 17.30%,and the energy consumption decreases by 4.20%and 25.69%,respectively.Finally,100 ILs in ILUAM are selected as the research objects,and ILs with high CO2 solubility and selectivity,which is used for CO2 absorption process,are screened by calculating their viscosity,solubility and selectivity.It is found that the solubility is related to the overlap degree and peak area ofs-profile,and the selectivity is related to the peak position and peak area ofs-profile.At last,the CO2 capture process is simulated and optimized,and it is found that the high solubility solvent is more conducive to CO2 capture.Moreover,the TAC of the process with mixed solvent as absorbent is reduced by 7.25%and 11.49%compared with that using high solubility or high selectivity solvents.Through the above research,this paper discussed the difference of separation performance between new solvents and organic solvents in extractive distillation,and extended the application of new solvents to process intensification and CO2 capture process,which can provided a strong theoretical basis for the industrial application of new solvents.