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Study On Separation Of Ethanol-Toluene Azeotrope By Combining Salt Extraction With Distillation

Posted on:2018-08-07Degree:MasterType:Thesis
Country:ChinaCandidate:Y LiangFull Text:PDF
GTID:2321330536475858Subject:Chemical processes
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High purity products could not be obtained from the azeotrope of ethanol and toluene by simple distillation method.Special distillation separation was the frequently used method for the separation.However,it has disadvantages such as the high consume of energy and high cost.In this dissertation,a process combining salt extraction with distillation was proposed for the separation of ethanol-toluene mixtures.(1)The liquid-liquid equilibrium data for different kinds of salt was measured at atmospheric pressure and 298.15 K and the selectivity coefficient and partition coefficient of composited extraction agent were calculated.Based on the obtained data,it is considered that water/potassium carbonate and water/potassium fluoride are the suitable extraction agent for the separation of ethanol-toluene mixture.(2)Liquid-liquid equilibrium(LLE)data were determined for the system at atmospheric pressure and 298.15 K.LLE data were measured for the system of ethanol-toluene-water-potassium carbonate at different temperature and atmospheric pressure.The experimental results show that the selectivity coefficient and partition coefficient of the water-potassium carbonate are much larger than 1 and both decreased with the increase of extraction temperature.The reliability test on experimental data was carried out by Rajendran's improved Eisen-Joffe model,which shows least correlation coefficient of 0.994 and maximum standard deviation of 0.05.The thermodynamic model parameter was obtained by using NRTL equation to correlate the data of ethanol-toluene-water-potassium carbonate at different temperatures and ambient pressure.The calculated value agrees with the experimental results well.(3)LLE data were determined for the system of ethanol-toluene-water-potassium fluoride at atmospheric pressure and 298.15 K.The reliability test on experimental data was carried out by Rajendran's improved Eisen-Joffe model,which shows least correlation coefficient of 0.993 and maximum standard deviation of 0.05.The thermodynamic modelparameter was obtained by using NRTL equation to correlate the data of this system.The calculated value agrees with the experimental results well.(4)The process combining salt extraction with distillation was proposed for the separation of ethanol-toluene mixtures,and was simulated by using Aspen plus,NRTL model parameter used experimental data fitting.The simulation results show that the mass fraction of seperated toluene and ethanol were 0.995 and 0.941 respectively when theoretical plate numbers of T1 extraction tower and T2 extraction tower are 5 and 10respectively;the theoretical plate number and reflux ratio of toluene recovery tower are 20 and 2 respectivly;the theoretical plate number and reflux ratio of ethanol recovery tower are 20 and 5 respectively.
Keywords/Search Tags:ethanol-toluene, Eisen-Joffe equation, NRTL model, combining salt extraction with distillation
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