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Petlyuk distillation


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I've been thinking a lot about still design, and I was wondering if anyone had ever seen a Petlyuk style column in use for ethanol? We tend to think of our distillations as a binary water-ethanol system, but it's actually a three or 5 or 10 part system if we start to consider the congeners. I think reducing it to a 3 part system (heads-ethanol-water) is most efficient...

I was mostly thinking that a large-scale continuous system could use this for a continuous heads draw as well as hearts.

anyone seen something like this? Am I way off the mark, or are they as common as dirt in big ethanol plants?

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Yes, this is exactly the way it is done in a large scale Neutral Spirit plant. A typical plant would have a stripper followed by a primary rectifier which has 3 off takes (plus minor off takes for fusels etc). The main product stream from the rectifier would be taken off about 5 or 6 trays down from the top while the heads stream would go to the recovery (feints) column. The main product steam is diluted down to 12-20% and put through a hydroselection column and the bottoms from this are fed to the secondary (potable) rectifier where again a 3-way split is made with the heads also going to recovery. I do not have personal experience of using this method for producing character spirits, but I have seen posts here by people who are doing it - although I think they were using more than 3 off takes.

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Gotcha...coincidentally, I found a diagram last night that showed this...it lacked plate detail, but had the system of retorts and catchcarry heating and cooling coils. It was from a diageo plant.

Steven, what is the footprint of your entire continuous system? Have you done any runs yet, to know what kind of steam requirements you have?

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I think there is some confusion as to what exactly a Petlyuk Column is, but maybe not.

It's not just a column with a side stream taken off. It's a way of taking two traditionally separate columns and turning it into one by adding a dividing wall vertically through a set of trays. It has the advantage of having a combined condenser and reboiler, but the control becomes more complicated (as compared to two columns in series), due the number of degrees of freedom

It's actually quote ingenious and could work well for this application. It's like combining the stripper and rectifier into one.

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agporte, my post may have been a bit vague...the diagram I found was for a true Petlyuk, not just a "system of columns," and that was indeed what I was asking about.

Do you know if Aspen Distil supports Petlyuk modeling? I haven't been able to find out, and although I don't have direct access to Aspen, I can have sims run for me. I'm not sure if the increased complexity of build is really worth the effort, but I'd like to figure out how efficient it might be BEFORE putting effort into a prototype or proof-of-concept build. The thermodynamics of the shared wall makes it quite complex to figure on paper.

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Check this out.


I hope I got the link correct.

I think it is neat to put two columns in one instead of connected in series. But it comes down to time/money, but they do show the purity is off the chart.

I like the idea.

A new way of looking at an old idea.

I might try to build one when I can find the time.


Take care.

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