Cuts and separating fusel oils and volatiles

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Cuts and separating fusel oils and volatiles

Postby artooks » Sun Jan 21, 2018 12:10 pm

Hi Everyone,

I have been reading about boiling points of alcohols and how not to get them, first of all I would like to explain how I do it, and will move on to my question, I always do a stripping run in my capped ccvm still so I run it as a pot still in the stripping run, I collect the first 200 ml and discard it, then I run until I reach 30% ABV so at that point my boiler temperature reaches 98 and the vapour temperature reaches 97 first question as far as I read there is not a problem to go to that level since I am not making cuts but at the same time I am also introducing the propanol so my first question is ? Can I safely collect until 20%-30% in a stripping run, because in some threads it is said to collect until 95 vapour temp.

In the spirit run I dilute the low wines first and use my ccvm reflux still to distill, I collect in 250 ml vessels and air them for a day or two taste and smell them with equal amount of water and alcohol from each vessel and decide which ones to keep as hearts and feints at the end, this is my way to do it, but there is something that is not very clear even after reading tons of threads in here and the mother site, that is at first I am using a pot still and run it till the end collect everything then in the spirit run I use the reflux still, so in refluxing everything is much more compressed and unfortunately I cannot track the vapour temp correctly so I do not know where I am during the run only at the far end when the alcohol starts to depleted the abv decreases and the vapour temp rises very quickly at that point I am already done, so because of that is there a chance that I am introducing propanol in the hearts of course the idea of the cuts is to separate the volatiles and get the ethanol but for safety issues I am wondering if it smears in ethanol and if it could cause a build up and cause health issues, could you please read and comment if I am doing the right thing or maybe I am worried too much for nothing, it is just that I read some threads about propanol and other volatiles and wanted to be sure of, thanks.
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Re: Cuts and separating fusel oils and volatiles

Postby still_stirrin » Sun Jan 21, 2018 1:01 pm

artooks wrote:...doing the right thing or maybe I am worried too much for nothing...

Yes...and yes.
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Re: Cuts and separating fusel oils and volatiles

Postby zapata » Sun Jan 21, 2018 1:47 pm

Details at the level you are asking about will vary from stillers to stillers, rig to rig, and desired product.

In general the way I run a reflux still is the same as you for stripping. Nothing wrong with the way you are doing that. For the spirit run my main feedback is a thermometer 1/3 down the column. I often have other thermometers (at the collection head/s, boiler, etc), but the 1/3 down column therm is the main feedback. I run at full reflux to reach equilibrium, and slowly bleed off fores and heads. Usually the 1/3 column therm will rise slowly through heads as the lower bp congeners are pushed higher, always the head therm rises slowly through heads. I DO NOT make the cut based on these readings, but they do give you feedback. As heads pass, the head therm and 1/3 column therm will be at the same temp, or as close as they can based on their precision. Whatever they read at this point is what I shoot for the rest of hearts. If you know your still, you will recognize this on the fly. If not, a brief re-equalizing period after heads will show you the lowest temp possible on your 1/3 therm.

The 1/3 column temp is handy because if it increases during hearts it tells me I am taking off too fast BEFORE that reaches my takeoff head. Manipulate takeoff/reflux as much or as little as you want to maintain equilibrium of the 1/3 therm, and also maximise takeoff speed if you care to. I usually don't care to, a reflux run is gonna be long no matter what, and I'd rather err on the side of higher purity than saving less than 10% time.

For a VM column, you can pretty much run rock steady through 90% hearts, the principle of VM will automatically adjust your reflux rate and reduce your takeoff rate as the run progresses. Eventually tails start to reach the 1/3 therm and it bumps up .1 degree. At this point you can choose to
A) run out tails
B) stop takeoff, re equilibriate, and take a bit more hearts
C) just give up, leave tails in the boiler and call it a day

I tend to go with C. I have little interest in neutral tails, and I've already spent a lot of time getting my heads and hearts out.

That's the best I can do using thermometers. Depending on still and wash particulars, there will still be some smearing that happened. So cuts are made by nose and taste after airing out.

Many people are happy with a less purified neutral. In that case the temperature they run at will usually be a bit higher than what it is at equilibrium (full reflux, no takeoff). You can still run the same way, as even at a lower purity the 1/3 therm will be steady after it initially rises a bit when hearts takeoff commences. This will mostly be a balancing act between column height, packing material, reflux rate, desired purity and patience.

If you only have a therm at the head, you can run it steady too. At a given takeoff rate it will not fluctuate during hearts. However it gives you no warning, when it increases you are already taking off that product.
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Re: Cuts and separating fusel oils and volatiles

Postby artooks » Mon Jan 22, 2018 11:09 am

Hi Zapata what is 1/3 thermometer unfortunately in my reflux column I cannot read the temp correctly.
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Re: Cuts and separating fusel oils and volatiles

Postby zapata » Tue Jan 23, 2018 5:47 pm

I have a thermometer one third of the way down my column, not just at the takeoff. Say your column is 1 meter, put a thermometer 33 cm beneath your takeoff (66 cm above your pot).

Why can't you read temps? Without a lot of experience with a particular rig, I can't imagine running a reflux still very well without at least one thermometer in the column or the still head. A boiler thermometer is near useless for running a reflux still, it will only give you an idea of how far into a run you are, not how well you are running. EG at some point a still with 0% reflux making 30% product will have the same boiler temperature as one with 9:1 reflux making 95%+.
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Re: Cuts and separating fusel oils and volatiles

Postby artooks » Wed Jan 24, 2018 1:00 am

Hi,

I have a thermometer in my ccvm still but it is in the right side of the tee and unfortunately it does not give me accurate temp, even I put it in the left hand side there is reflux that goes back to the boiler so in a reflux column it is really hard to read the correct temp is there a way ?
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Re: Cuts and separating fusel oils and volatiles

Postby BayouShine » Wed Jan 24, 2018 6:39 am

artooks wrote:Hi,

I have a thermometer in my ccvm still but it is in the right side of the tee and unfortunately it does not give me accurate temp, even I put it in the left hand side there is reflux that goes back to the boiler so in a reflux column it is really hard to read the correct temp is there a way ?

With the way your still is set up, you don't need a thermometer in the column at all. As you can already see, it's pretty useless. It would be better served to monitor the cooling water output and use the sight glass to drive this rig.
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