[BreakingBad20]

I am in the process of finishing off my hysys simulation but I have run into problems with purifying the acetaldehyde and separating the ethanol so it can be recycled back into the system. I have tried various temperatures and pressures aswell as various unit operations to try and separate ethanol, acetaldehyde and water but nothing seems to be working effectively. I was hoping someone could help me out as I'm running out of options 

P = 1 ATM
T = 303K
Molar flow rate = 5194 kg.mol/hr

Molar fraction:
Acetaldehyde: 0.0679
Ethanol: 0.8940
Water: 0.0381

[curiouscat]

Can you post more details about your simulation results? Why doesn't it work? Are they forming any azeotropes?

What purities do you need? What are your constraints?

A wacky option comes to mind. Butane and Acetaldehyde form a low boiling azeotrope which boils at -7 C. If you strip your mixture with butane you might be able to separate off a {Butane (~84%) + Acetaldehyde (~16%)}  mixture. Though how to split that is another question.

[BreakingBad20]

Didn't see this at the time. For the marking that was in it for this project and the fact my lecturer wanted to just see that we can use Hysys, I put the stream through a component splitter which separates what you want. This allowed me to simulate the distillation process with Acetaldehyde and Water and I was also able to purify the ethanol to bring it back into a recovery stream!

[curiouscat]

Didn't see this at the time. For the marking that was in it for this project and the fact my lecturer wanted to just see that we can use Hysys, I put the stream through a component splitter which separates what you want. This allowed me to simulate the distillation process with Acetaldehyde and Water and I was also able to purify the ethanol to bring it back into a recovery stream!

"component splitter"!!! Now why didn't I think of that! 

[BreakingBad20]

It was a quick fix more than anything however, if I'm faced with this problem next year in my design project I will more than likely have to take into consideration azeotropes!