There has a been a windows computer program released a week ago by Vaxa Software called Design of Distallation Columns and according to their description it sounds like it may be uesfull. I have download a demo version to have a look at it.
The link to web page is below if anyone also wants to have a look at it.
http://downloadnew.org/education/scienc ... 89119.html
cheers, Icarus