I've put together a simple calculation of %purity vs time for a Pot still.
(I've done this as a warm-up exercise for a reflux column).
See what you think of it ..
The trouble is that i don't have a pot still of my own to calibrate the calculations against. I've guessed that there is an internal reflux of around 25% happening. For those of you with pot stills - does this appear right ? Does it give the sort of purity vs time that you experience ?
It's also usefull for doing double-distillation calcs with,
eg : 20L of 15% will yield around 5.9L of 45% product in 160 minutes (using a 25% cutoff),feed this back into it as the starting material, and get 3.9L of 68% product in 80 minutes (if 20% cutoff used).
Its a very crude calculation that it does - simply assumes that the distillate comes off at constant purity during all the time-step. So real big time steps give bad/strange answers. But its only my first attempt.
Any comments gratefully accepted.