Areas of energy advantage for flowsheets of separation modes for mixtures containing components with similar volatilities

Objectives. The conditions for the effective application of the sharp distillation technique (without a component distributed between the distillate and bottom flows) for the separation of quaternary zeotropic mixtures containing components with similar volatilities were determined. The area of energy advantage for the flowsheet based on the preliminary fractionation of the mixture, compared with the flowsheet, the first distillation column of which works based on the indirect separation mode, was identified for an ethyl acetate–benzene–toluene–butyl acetate system. Energy savings of up to 20% were achieved. The direct and indirect distillation modes can become competitive when the point of the original composition is located near single K-surfaces or in a region with a different ratio of distribution coefficients. Sharp distillation is not suitable for the separation of a mixture containing a pair of components exhibiting relative unity volatility with medium boiling points.

Methods. The mathematical modeling in the Aspen Plus V.10.0 software package was chosen as the research method. The simulation was based on the Wilson local composition equation. The relative errors in the description of the phase equilibrium did not exceed 3%.

Results. The structure of the vapor–liquid equilibrium diagram and diagram of surfaces of the unit component distribution coefficients were studied for the ethyl acetate–benzene–toluenebutyl acetate and acetone–toluene–butyl acetate–o-xylene systems. Flowsheets based on the sharp, indirect (both systems), or direct (second system) distillation modes were proposed. The distillation process was simulated, and the parameters of the column work were determined (the quality of the substances meets the State Standard requirements of the Russian Federation for minimal energy consumption).

Conclusions. Recommendations regarding the use of sharp distillation for the separation of quaternary mixtures containing components with similar volatilities were devised.

1. Zharov V.T., Serafimov L.A. Fiziko-khimicheskie osnovy distillyatsii i rektifikatsii (Physico-chemical principles of distillation and rectification. Leningrad: Khimiya; 1975. 240 p. (in Russ.).

2. Timofeev V.S., Serafimov L.A., Timoshenko A.V. Printsipy tekhnologii osnovnogo organicheskogo i neftekhimicheskogo sinteza (The principles of the technology of basic organic and petrochemical synthesis). Moscow: Vysshaya shkola; 2010. 408 p. (in Russ.). ISBN 978-5-06-006067-6

3. Frolkova A.K. Razdelenie azeotropnykh smesei. Fiziko-khimicheskie osnovy i tekhnologicheskie priemy: monografiya (Separation of azeotropic mixtures. Physicochemical fundamentals and technological methods). Moscow: VLADOS; 2010. 192 p. (in Russ.).

4. Petlyuk F.B. Distillation Theory and Its Application to Optimal Design of Separation Units. Cambridge, UK: Cambridge University Press; 2004. https://doi.org/10.1017/CBO9780511547102

5. Green D.W., Southard M.Z. (Eds.). Approximate Multicomponent Distillation Methods. In: Perry’s Chemical Engineers’ Handbook. New York, USA: McGraw-Hill Education; 2019. Section 13. P. 25-28.

6. Mavletkulova P.O., Serafimov L.A., Danilov R.Yu. Comparative Analysis of Sharp Separation Regimes in the Distillation of Ternary Zeotropic Mixtures. Theor. Found. Chem. Eng. 2014;48(5):622-628. https://doi.org/10.1134/S0040579514050200

7. Serafimov L.A., Chelyuskina T.V., Mavletkulova P.O. Special Distillation Regime Involving an Infinite Reflux Ratio and an Infinite Number of Separation Stages. Theor. Found. Chem. Eng. 2014;48(1):48-54. https://doi.org/10.1134/S0040579514010138

8. Khalili-Garakani A., Ivakpour J., Kasiri N. Threecomponent Distillation Columns Sequencing: Including Configurations with Divided-wall Columns. Iranian J. Oil Gas Sci. Technol. 2016;5(2):66-83. https://dx.doi.org/10.22050/ijogst.2016.15799

9. Frolkova A.V., Peshekhontseva M.E., Gaganov I.S. Sharp separation for quatrenary mixtures. Tonk. Khim. Tekhnol. = Fine Chem. Technol. 2018;13(3):41-48 (in Russ.). https://doi.org/10.32362/24106593-2018-13-3-41-48

10. Kleymenova M.N., Komarova L.F., Lazutkina Y.S. Technology for Treatment of Solvents’ Liquid Waste from Silicone Enamels Production. Ekologiya i promyshlennost՚ Rossii = Ecology and Industry of Russia. 2014;3:11-15 (in Russ.).

11. Il’ina E.S., Tarasova M.N., Lazutkina Yu.S. The study of the physicochemical properties of solvent components in the production of epoxy primers. In: Proc. 3rd Russian scientific and technical conference of students, postgraduates and young scientists “Science and Youth.” Section “Chemical technologies.” Subsection “Chemical engineering and engineering ecology.” Barnaul: Polzunov Altai State Technical University; 2006. P. 27-28 (in Russ.).

12. Mato F., Bonilla D., Benito G. Liquid-vapor equilibrium of the n-heptane-isobutyl acetate, toluene-isobutyl acetate, and toluene-n-butyl acetate systems at 760 mmHg. An. Quim. 1991;87:660-663.

13. Carr A.D., Kropholler H.W. Vapor Liquid Equilibria at Atmospheric Pressure. Binary Systems of Ethyl AcetateBenzene, Ethyl Acetate-Toluene, and Ethyl Acetate-p-Xylene. J. Chem. Eng. Data. 1962;7(1):26-28. https://doi.org/10.1021/je60012a007

14. Gupta B.S., Lee M.-J. Isobaric vapor-liquid equilibrium for binary systems of toluene + o-xylene, benzene + o-xylene, nonane + benzene and nonane + heptane at 101.3 kPa. Fluid Phase Equilib. 2013;352:86-92. https://doi.org/10.1016/j.fluid.2013.05.016

15. Kogan V.B. Azeotropnaya i ekstraktivnaya rektifikatsiya (Azeotropic and extractive distillation). Leningrad: Khimiya; 1971. 432 p. (in Russ.).