화학공학소재연구정보센터
Journal of Chemical and Engineering Data, Vol.61, No.12, 4077-4084, 2016
Effect of Phase-Equilibrium Uncertainties on the Separation of Heterogeneous Azeotropes-Application to the Water+1-Butanol System
This paper extends application of the Margules-based phase-equilibrium uncertainty method to a system exhibiting a heterogeneous azeotrope. The author developed the method in order to provide practicing engineers with an intuitive and easy-to-apply procedure to quantitatively relate process-design uncertainties to uncertainties in correlated physical properties, specifically nonideal phase equilibrium. The methodology was first applied to two case studies-(1) a propylene-propane superfractionator for which small changes in correlated relative volatilities have a large effect on the design of the distillation column; and (2) a dehexanizer column that separates a mixture containing many close-boiling hydrocarbon components-and demonstrated that the proposed method provides quantitative insight into the effect of property uncertainties for both these diverse process designs and helps to quantify the safety factors that need to be imposed upon the design. In a subsequent study, the methodology was applied to a distillation train that separates the acetone-chloroform-benzene ternary mixture, which contains one maximum-boiling azeotrope, and showed that the approach quantifies the effect of property uncertainties on utility consumption and also identifies limits on operating variables (specifically minimum recycle flow). In this paper, the Margules perturbation method is applied to the separation of the water + 1-butanol binary mixture. The application is complex because this binary exhibits liquid-liquid equilibrium and forms a minimum-boiling azeotrope, and the typical separation scheme includes a decanter as well as two distillation columns. Further, the chosen activity-coefficient model is unable to correlate the data within measurement uncertainty. Nevertheless, the methodology is demonstrated to provide useful quantitative estimates of the design uncertainty resulting from the combined measurement/model phase-equilibrium uncertainty.