A general overall feasibility methodology of batch reactive distillation of multireaction systems is developed to study all the possible configurations of batch reactive distillation. The general model equations are derived for multireaction system with any number of chemical equilibrium-limited reactions and for any number of components. The present methodology is demonstrated with the detailed study of the transesterification of dimethyl carbonate in two reversible cascade reactions in batch reactive distillation process. Pure methanol is produced as distillate, and pure diethyl carbonate is produced at the bottom simultaneously in middle-vessel column; in each section, continuous feeding of ethanol is necessary. The results of feasibility study are successfully validated by rigorous simulations. 1. Introduction Reactive distillation is a hybrid process integrating separation and reaction in a single unit. The main advantages of reactive distillation compared to the sequential processes include reduced investment and operating costs, reduced utility consumption, and higher conversion and selectivity [1]. Nevertheless, reactive distillation is not advantageous in every case, and systematic methods are needed to examine its feasibility for particular reaction systems. Design of complex processes usually starts with feasibility analysis including computation of limiting flows and minimum stage numbers as well. Quick, simple, and reliable method is needed to find the best feasible configurations and parameter regions applicable to produce the desired products. Several methodologies for the preliminary study of reactive distillation have been published in the past decades; short overview is in Stéger et al. [2]. Many of them are based on graphical techniques providing a basis for developing conceptual designs (e.g., in the articles of [3–6]). In spite of the efforts, their application is still limited because of the lack of a systematic design method applicable in general case, especially for complex column configurations [2, 7]. All the possible configurations of batch reactive distillation with equilibrium-limited single reactions in rectifier with reactive boiler can be analyzed with the reliable, overall feasibility method suggested by Stéger et al. [2]. Only configurations with at most one feed are discussed there but the method can be extended for several entrainer feeds [7]. In the present work, we extend our general feasibility method for any number of equilibrium-limited reactions in middle-vessel column, stripper, and rectifier. The version
References
[1]
M. F. Malone and M. F. Doherty, “Reactive distillation,” Industrial and Engineering Chemistry Research, vol. 39, no. 11, pp. 3953–3957, 2000.
[2]
C. Stéger, T. Lukács, E. Rév, M. Meyer, and Z. Lelkes, “An overall feasibility study of batch reactive distillation in hybrid configurations,” AIChE Journal, vol. 55, no. 5, pp. 1185–1199, 2009.
[3]
D. Barbosa and M. F. Doherty, “Design and minimum-reflux calculations for single-feed multicomponent reactive distillation columns,” Chemical Engineering Science, vol. 43, no. 7, pp. 1523–1537, 1988.
[4]
J. Espinosa, “On the integration of reaction and separation in a batch extractive distillation column with a middle vessel,” Industrial and Engineering Chemistry Research, vol. 41, no. 15, pp. 3657–3668, 2002.
[5]
J. Espinosa, P. A. Aguirre, and G. A. Perez, “Product composition regions of single-feed reactive distillation columns: mixtures containing inerts,” Industrial and Engineering Chemistry Research, vol. 34, no. 3, pp. 853–861, 1995.
[6]
J. Espinosa, P. Aguirre, and G. Perez, “Some Some aspects in the design of multicomponent reactive distillation columns with a reacting core: mixtures containing inerts,” Industrial and Engineering Chemistry Research, vol. 35, no. 12, pp. 4537–4549, 1996.
[7]
R. M. Dragomir and M. Jobson, “Conceptual design of single-feed hybrid reactive distillation columns,” Chemical Engineering Science, vol. 60, no. 16, pp. 4377–4395, 2005.
[8]
C. Stéger, R. Thery, X. Meyer, M. Meyer, M. Brehelin, and D. Amoros, “étude de faisabilité de l'estérification d'un diacide par distillation réactive,” Oil & Gas Science and Technology—Revue d'IFP Energies nouvelles, vol. 65, no. 5, pp. 703–719, 2010.
[9]
H.-P. Luo and W.-D. Xiao, “A reactive distillation process for a cascade and azeotropic reaction system: carbonylation of ethanol with dimethyl carbonate,” Chemical Engineering Science, vol. 56, no. 2, pp. 403–410, 2001.
[10]
Z. Lelkes, P. Lang, B. Benadda, and P. Moszkowicz, “Feasibility of extractive distillation in a batch rectifier,” AIChE Journal, vol. 44, no. 4, pp. 810–822, 1998.
[11]
C. Stéger, V. Varga, L. Horváth et al., “Feasibility of extractive distillation process variants in batch rectifier column,” Chemical Engineering and Processing, vol. 44, no. 11, pp. 1237–1256, 2005.
[12]
V. Varga, E. R. Frits, and V. Gerbaud, “Separation of azeotropes in batch extractive stripper with intermediate entrainer,” in Proceedings of the 16th European Symposium on Computer Aided Process Engineering, (ESCAPE '06) and 9th International Symposium on Process Systems Engineering, (PSE '06), Garmisch-Partenkirchen, Germany, July 2006.
[13]
C. Stéger, E. Rév, L. Horváth, Z. Fonyó, M. Meyer, and Z. Lelkes, “New extractive configuration separating azeotropic mixture in semi-batch way,” Separation and Purification Technology, vol. 52, no. 2, pp. 343–356, 2006.
[14]
M. Doherty and G. Buzad, “Reactive distillation by design,” Transactions of the Institution of Chemical Engineers, vol. 90, no. A, pp. 448–458, 1992.
[15]
H.-P. Luo, W.-D. Xiao, and K.-H. Zhu, “Isobaric vapor-liquid equilibria of alkyl carbonates with alcohols,” Fluid Phase Equilibria, vol. 175, no. 1-2, pp. 91–105, 2000.
[16]
K. Sundmacher and A. Kienle, Eds., Reactive Distillation, Wiley-VCH, Weinheim, Germany, 2002.
