There is an Open Source Chemical Process Simulator available!
At the university I used mainly the proprietrary ChemCAD and Aspen Plus, but DWSIM is also amazing. I really like open cource software! As their website states, DWSIM was born in 2004 from Excel VBA macros which implemented the PR EOS and a basic Flash Algorithm.
I really like it when someone develops their own tools to solve their special problems, because you can learn a lot about the topic in the process.
