Residue Curve Map for a Benzene-Toluene-p-Xylene Mixture

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The Demonstration computes the residue curve map for the ternary mixture benzene-toluene-p-xylene. When you change the locator's position, a new residue curve is computed and displayed. Residue curve maps play an important role in the conceptual design of distillation columns.


The position of the locator gives an initial point from which the simulation runs forward and backward in warped time. The lightest (benzene) and the heaviest (p-xylene) components are the unstable and stable nodes. The distillation gets richer in the heavy components until there is only p-xylene left. The intermediate component (toluene) is a saddle point. All three are extremes of the system of differential equations. If the locator is outside the triangle then the point does not correspond to a realistic mixture (i.e., it has mole fractions that are negative or greater than 1). If the user chooses a locator inside the triangle, its two coordinates correspond to the mole fractions of benzene and p-xylene (. The third (toluene’s) mole fraction is . The plot is the residue curve of the ternary mixture that represents the composition of the distillation still versus warped time.


Contributed by: Housam Binous (March 2011)
Open content licensed under CC BY-NC-SA



For more information, see:

M. F. Doherty and M. F. Malone, Conceptual Design of Distillation Systems, New York: McGraw-Hill, 2001.

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