Q & A > Question Details
I am a student of the energy operations class st Lake Area Tech. Our goal is to improve the purity of our ethanol from 95% to a much higher purity. We are using a 2in x 60in copper pipe instead of the 5in x 17in steel pipe for our distillation column, and trying to pack it with Raschig rings instead of the marbles the last class used.
1. I am having trouble determining the packing height needed, or the amount of Raschig rings that need to be used. (The volume of the tower is roughly 4 Liters)
2. Does there need to be empty space in between the rings or should they be just dumped in randomly?
3. Where in the column should the reflux outlet be placed for maximum return to the base of the still?
Any answer to any question would be GREATLY appreciated! Keep in mind I am not a chemical engineer, but I am familiar with most of the theories and some of the math such as HETP, plates vs packing, random vs structured and so on.
 
Answers
16/11/2015 A: keith bowers, B and B Consulting, kebowers47@gmail.com
The first step is removing the water! You must use another component to break the azeotrope so you distill the added component and water overhead, leaving 99.9%? pure ethanol.
You may have to pull a slight 'purge' or 'bottoms product from the bottom reboiler feed to remove 'high boilers' in the raw ethanol.
Top reflux is used to 'rectify' the top product and knock down any higher boiling components. For sake of learning by experiment, install 4 reflux returns , starting 18 " from the top of packing and then every 6" down---and experiment to find which return point works best.