jamesbanda,
I agree concerning the importance of properties, that is the reason why I suggested two different solutions:
A VBA code for mass balance based on Thiele Geddes method (which could be extended with energy balance based on constant composition method and possibly rigorous properties)
A complete rigorous solution (Prode Properties) based on Newton method and rigorous properties.
Of course for solving a column there are many process simulators with rigorous thermodynamics but these are (in general) much more expensive (with some exception as Chemsep)
in addition I wouldn't underrate the importance of classic short cut methods as Fenske-Underwood-Gilliland, these are easily implemented in Excel and can provide real knowledge about multistage separation...
there is a paper "Shortcut distillation calculations via spreadsheets", Chemical Engineering Progress, Dec. 2002 which describes the procedure.
When most engineers at meetings only say "I did it with my $$$ simulator" I wonder how much Excel (and knowledge of process operations) can be useful in everyday work
thanks all,
I use my own procedures and I can discuss the details, codes etc. with my clients, I understand that for such complex things as columns this is unrealistic but anyway it keeps me quite proud of my job...