Thiele-Geddes Multicomponent Distillation

 Multi-Component Distillation Calculation

Thiele-Geddes Method with Theta Convergence

The VBA program in the attached spreadsheet performs rigorous tray-by-tray calculations for multi-component distillaton by the Thiele-Geddes method with the theta convergence technique proposed by Holland. The technique involves material balance performed from the top of the column including the condenser to the feed tray and from the reboiler at the bottom to the feed tray. 

The algorithm involves using iterative techniques to solve a large number of non-linear equations.   The iterative theta convergence and bubble point algorithm are nested inside the plate to plate calculations. This technique is fast for solving these equations and is illustrative of chemical engineering principal, but not as versatile as sparse matrix technique typically employed my large process simulation programs. It will work best used for solutions that do not deviate too greatly from ideality.

The vapor-liquid equilibrium is expressed as a function of temperature with a polynomial relationship, but this can be easily changed in the code. The program numbers stages starting at the top of the column. It allows for either a partial or total condenser.  A partial condenser would be counted as the first stage of seperation. 

References

Holland, C.D.,"Fundamentals of Multicomponent Distillation", Mcgraw-Hill Book Company, 1981. P.49-75.

Thiele, E.W., and R.L. Geddes, Ind. Eng. Chem., 25, 289 (1933)

Hines, A.L., and R.N. Maddox, "Mass Transfer", Fundementals and Applications, Prentice Hall, 1985. P. 363-368.

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