Distribution of heat exchange in optimum diabatic distillation columns

We improved our model for minimization of entropy production rate in diabatic tray distillation. The entropy production rate had contributions from heat and mass transfer on the trays and from heat exchangers connected to the trays. The area of the heat exchangers were not used as free variables, but calculated from four different area distribution rules. The total heat exchange area and its distribution over the column had a significant effect on the entropy production rate in the system. In the limit of infinitely large forces, the results of an adiabatic column were obtained, as expected. As the forces became smaller, the distribution of the area became more important. The area distribution rule with constant average force in each heat exchanger had the lowest entropy production rate of the rules used. Possible consequences for column design were discussed, and a sketch with the characteristics of an optimum distillation column was presented. Two minimization algorithms were used with similar outcome; the Matlab® function fmincon being the fastest.

[1]  Philip E. Gill,et al.  Practical optimization , 1981 .

[2]  Signe Kjelstrup,et al.  Minimizing the entropy production in heat exchange , 2002 .

[3]  Kristian M. Lien,et al.  DIABATIC COLUMN OPTIMIZATION COMPARED TO ISOFORCE COLUMNS , 1997 .

[4]  Z. Fonyo.  THERMODYNAMIC ANALYSIS OF RECTIFICATION - 2. FINITE CASCADE MODELS. , 1974 .

[5]  J. Smith,et al.  Introduction to chemical engineering thermodynamics , 1949 .

[6]  Karl Heinz Hoffmann,et al.  The Influence of Heat Transfer Irreversibilities on the Optimal Performance of Diabatic Distillation Columns , 2002 .

[7]  Ricardo Rivero.  Exergy simulation and optimization of adiabatic and diabatic binary distillation , 2001 .

[8]  Ricardo Rivero Rodriguez,et al.  L'analyse d'exergie : application à la distillation diabatique et aux pompes à chaleur à absorption , 1993 .

[9]  Daniel Tondeur,et al.  Equipartition of entropy production. An optimality criterion for transfer and separation processes , 1987 .

[10]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[11]  Z. Fonyo,et al.  THERMODYNAMIC ANALYSIS OF RECTIFICATION - 1. REVERSIBLE MODEL OF RECTIFICATION. , 1974 .

[12]  Kristian M. Lien,et al.  Equipartition of Forces: A New Principle for Process Design and Optimization , 1996 .

[13]  James M. Douglas,et al.  Conceptual Design of Chemical Processes , 1988 .

[14]  G. D. Koeijer,et al.  Entropy production and exergy loss in experimental distillation columns , 2003 .

[15]  Charles Edward Littlejohn,et al.  An introduction to chemical engineering , 1959 .

[16]  J. A. Wesselingh.  Non-equilibrium modelling of distillation , 1997 .

[17]  Signe Kjelstrup,et al.  Equipartition of forces as a lower bound on the entropy production in heat exchange , 2001 .

[18]  S. Kjelstrup,et al.  Transport equations for distillation of ethanol and water from the entropy production rate , 2003 .

[19]  Signe Kjelstrup,et al.  Minimizing Entropy Production Rate in Binary Tray Distillation , 2000 .

[20]  Karl Heinz Hoffmann,et al.  Numerically optimized performance of diabatic distillation columns , 2001 .

[21]  Walter L. Badger,et al.  Introduction to Chemical Engineering , 1955 .

[22]  J. Gaube.  J. Gmehling, U. Onken, W. Arlt: Vapor-Liquid-Equilibrium Data Collection, in der Reihe: Chemistry Data Series, Vol. I. Parts 3 + 4 Aldehydes and Ketones Ethers, Dechema, Frankfurt 1979. 624 Seiten. Part 6a Aliphatic Hydrocarbons C4-C6, Dechema, Frankfurt , 1982 .

[23]  Karl Heinz Hoffmann,et al.  Comparison of entropy production rate minimization methods for binary diabatic distillation , 2002 .

[24]  K. Kobe.  The properties of gases and liquids , 1959 .