Fusel side draw experiment

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Edwin Croissant
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Fusel side draw experiment

Post by Edwin Croissant » Sat Apr 28, 2018 10:34 am

For a theoretical background for this experiment see ABV dependent volatility of fusel oils

ketel3 and I did an experiment with the objective to test cheap peristaltic pumps as a substitute for a needle valve and to find out the effect of removing the fusel alcohols (tails) oil through side drawing from the column at approximately 10 cm from the bottom. I will not discuss the benefits of these pumps as distillate pump as they contain about 15 cm of silicone tubing and are therefore against the rules of this forum. As long as the fusel draw is not consummated (I can't imagine that anyone will be tempted to do so) or is reused, the use of such pump is a cost effective way to control the flow rate.

Ketel3 adapted his column with a side connection for the withdrawal of the fusel alcohols and placed a temperature sensor in the middle.

I made a test box that controlled the two peristaltic pumps, record the temperature value in the middle of the column, and record the flow and volume of the fusel alcohols and the distillate. To measure the last two parameters little magnets were mounted inside the rollers of the pumps and Hall sensors were used to detect the passing of those magnets while the pump was running. An Arduino was used to display the quantity and flowrate of the distillate and fusel oil en to show the temperature in the mid of the column. The sensor used was a SMT172 TO18 with a resolution of 0.01 ºC The collected data was stored on a SD card. At the start of the test the fusel alcohols were withdrawn at a rate of about 10 cc/min, later during the run this was lowered to 5 cc/min.

The still was a 50 liter keg with a 50mm column. During the run power was about 1600 watt. Packing was loosely packed stainless scrubbers. Distillate and fusel alcohols were collected in jars.

Most of the fusel jars developed a 1 cm thick milky colored layer on top within a couple of minutes.

One of ketel3’s girlfriends works in the perfume industry and is equipped with a very good nose. Se sampled all of the distillate and fusel jars:

Wash was based on a of 11% sugar wash with a couple of cans of grape concentrate:
Distillate (5536 cc total ABV > 92%):
jar one: nail polish
jar two: not bad
jar three: sweet and useful
rest of the jars: excellent
last jar: faint hint of something but still acceptable. (200cc jar containing the very last of the ethanol in the boiler, ABV probably below 90%).

This batch was much better then previous ones distilled without the fusel alcohols side streaming.

Fusel oil (866cc total about 12% ABV)

All of the fusel jars had a very disagreeable odor, first one smelled like cognac, and one (jar 5 or so) had a rum caramel smell. Most of the jars made her nearly faint. Last fusel jar was tasteless water.

Fusel pump was a INTLLAB peristaltic pump, sold on AliExpress for about €5 including shipping. Pump tubing was changed to 4x2mm silicone tubing, interconnecting tubing was PTFE 3x2mm tubing.
Pump is 12V and can be controlled with a DC motor controller that cost less then €2 as sold on AliExpress. (The digital ones I used (about €4) are overkill but chosen as I was not sure if I could program the Arduino to display the flow rate at time of ordering) Fusel must be below 40C before entering the pump. (tape PTFE tube to cold coolant line for some distance)

After the test the conclusion was that the operation of the still was stable, the pumps operated flawlessly and the removal of the fusel alcohols at the bottom of the column gave a huge distillate quality improvement. Even the last jar that we squeezed out of the boiler was of acceptable quality. We also got the feeling that, based on the temperature reading of the mid sensor, the top part of the packing could be removed and the column could be shorted accordingly.

We know that this report lacks a lot of details as we had no idea what to expect but hope that this report is of some use.
Attachments
peristaltic pump take off.jpg
run.jpg
pompkast.jpg
fusel jar.jpg
fusel jars.jpg
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der wo
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Re: Fusel side draw experiment

Post by der wo » Sun Apr 29, 2018 8:50 am

Thanks Edwin,

I also recognized, that there must be a concentrated fusel aera somewhere down in the column. At one of my first long reflux neutral runs, at the end of the tails I thought, that now I will safe a bit time by open the valve of my LM and let it go fast until all alcohol is collected. Bad idea, because the smell became terrible suddenly (medical, menthol like?). When you have squeezed out most of the ethanol at 95%, and then full open the valve, the content of the column gets pushed upwards and soon this smell goes through the output.

I can imagine that a neutral run without this stinky layer at the bottom of the column turns out way better. But instead of building an bleed off, an additional run could solve the problem too perhaps?
Not the standard potstill stripping and reflux spirit run protocol, because the low abv potstill stripping wouldn't cut the isoamyl. But two reflux runs, here the stripping would cut the isoamyl. Perhaps moderate reflux is enough to keep the fusel layer down? A stripping run to 85%abv is perhaps enough? It doesn't need much reflux (time) for 85%. What abv is enough to keep the fusel layer down? In a batch distillation there is no definitive answer unfortunately, because the abv in the system is changing all the time.

Next experiments could be:
-other bleed off locations.
-multiple distillations. For example distilling potstill-stripped vs reflux-stripped low wines.
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Re: Fusel side draw experiment

Post by OtisT » Sun Apr 29, 2018 10:36 am

This is really cool. Thanks for sharing. This is now on my long list of cool things to try. :-)

You will get even better taste by eliminating or perhaps replacing that short piece of plastic tube from your condenser to your parrot with SS or copper. 90%+ alcohol will leach nasty chemicals out of plastic.

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Re: Fusel side draw experiment

Post by Edwin Croissant » Wed May 02, 2018 9:57 am

der wo wrote:But instead of building an bleed off, an additional run could solve the problem too perhaps?
You are right however a bleed off (could also be a miniature funnel with an elbow and a needle valve on the outside of the column) is a one time modification and on the long run more economical.
der wo wrote:What abv is enough to keep the fusel layer down?
If I recall correctly the ABV should be kept above 90 to 92% to prevent fusel alcohols to be carried over.
It seems however that the fusel alcohols in the column reduce the effective hight of the column.

As a side note based on the ABV of the fusel jars it might be that 10cm of loosely packed stainless scrubbers is not enough. According to Groening the maximum concentration happens at about 30% ABV and according to Sorel at about 43%. I got the impression that all of the graphs I have seen are based on one of these two values.
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Re: Fusel side draw experiment

Post by The Baker » Wed May 02, 2018 4:33 pm

Many years ago Harry on another forum suggested diluting stripped wash to I think 28% abv, resting for maybe a few days, and drawing off FROM BELOW THE SURFACE to re-distil.
I think it was fusel oils remain on the surface...

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Re: Fusel side draw experiment

Post by der wo » Thu May 03, 2018 1:32 am

So your "standard protocol" would be:

- refluxing for a while
- drawing off the fusels
- and then like always fores, heads, hearts and tails from the top of column.
Edwin Croissant wrote:As a side note based on the ABV of the fusel jars it might be that 10cm of loosely packed stainless scrubbers is not enough. According to Groening the maximum concentration happens at about 30% ABV and according to Sorel at about 43%. I got the impression that all of the graphs I have seen are based on one of these two values.
So if someone builds this and gets between 30 and 43%, he has placed the draw off probably right. Very useful information.

It would be great someone else experiments with it. I don't make often neutral spirits. And I have a large supply currently, perhaps for 10 years :D .
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Re: Fusel side draw experiment

Post by johnsparrow » Mon May 14, 2018 1:56 pm

If you are looking for vacuum it might be possible to run a venturi off you coolant flow.

Not that I totally understood the diagram, but it said 'suction' and I know that you could do this.

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Re: Fusel side draw experiment

Post by zapata » Mon May 14, 2018 10:44 pm

I dont understand the need for a pump at all. Surely this could all be accomplished with a simple liquid management style trap? Many people run stills with multiple "heads". I call them "traps" if they aren't at the tippity top. In fact they need not be much more complicated than a what some use for centering plates with an added valve.

I have run a still with 2 LM takeoff, 1 at the top, 1 a foot or so lower. I have designs drawn for one with a 3rd lower tails trap, though I haven't gotten around to it simply because I have 2 modular LM traps laying around, but not a third. And using the upper head to catch heads saves me time and hassle, where the lower tails trap seems like it would mostly allow me a shorter column. For a new build maybe this matters, but I already have up to 5' of column, and no motivation to shorten it, but saving time bleeding heads pays a benefit every run. This isnt a dis, just an excuse for why I haven't tested it yet.

Multiple sidestreams are typical in the industry, and not unheard of in the hobby. Why not apply that here instead of some pumping arduino robot contraption?

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Re: Fusel side draw experiment

Post by Edwin Croissant » Tue May 15, 2018 12:00 pm

Zapata, this started as a test to see if these kind of cheap pumps can be used as a needle valve. The fusel draw experiment was a nice spinoff. As stated by me earlier in this thread you can do the same with a take off and a needle valve. I am modifying a still at the moment and I am thinking about to run the suction lines inside the column, the lines are 3x2mm ptfe tubing so they do not occupy much space. No need for drilling holes and welding. And simple to automate, no expensive stepper controlled needle valve.

I am very interested in your experience with a second takeoff for the heads and the fores. I have seen this on the Franzmaster stills. What type and height of packing are you using? Please tell me more.
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Re: Fusel side draw experiment

Post by Tomb » Wed Dec 26, 2018 2:01 pm

Just wondering how you arrived at 100mm? Was it just an educated guess?
(8% of column height)

Seems like your results suggest it be placed higher up, possibly at 20 or 30% of column height?

I have switched from lava to marbles and need to find some takeoff that would be compatible with marbles and be easy to retrofit. Wondering if a simple “hole” to take just vapour (with enough cooling) might be all that is needed?

T

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Re: Fusel side draw experiment

Post by Edwin Croissant » Thu Dec 27, 2018 1:37 pm

Tomb wrote:Just wondering how you arrived at 100mm? Was it just an educated guess?
(8% of column height)

Seems like your results suggest it be placed higher up, possibly at 20 or 30% of column height?

I have switched from lava to marbles and need to find some takeoff that would be compatible with marbles and be easy to retrofit. Wondering if a simple “hole” to take just vapour (with enough cooling) might be all that is needed?

T
It was a value I found on a Russian forum and the results indicate that the takeoff should be placed a little bit higher.
Maybe a vapor ABV would be just right at 100 mm, so a vapor takeoff with a valve followed by a water or maybe air cooled worm might do the trick and would be a very simple solution.

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Re: Fusel side draw experiment

Post by Tomb » Sun Jan 20, 2019 12:43 am

Edwin:

You did not give details on the take off collection? I am going to use a 1/2” copper pipe cap (with tabs cut and bent to prevent marbles from entering) with 1/4 pipe off the bottom and through the side wall.

I am still trying to decide the height. From your drawing, yours was 100mm or 8% of height and got about 12%abv.
I have a similar height column (1200mm) and will likely go for 1/4 of that or 300mm.

Or do you think somewhere around 200mm might be better?

T

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Re: Fusel side draw experiment

Post by OtisT » Sun Jan 20, 2019 9:07 am

Edwin and Tomb,
I don’t think you would want to pull vapor. Wouldn't rising vapor contain a mix of alcohols yet to be separated? It’s only the liquid down at a specific temp in an alcohol stacked column where you can identify it as a separated alcohol? I’ve not built one myself, so consider the source. ;-). Otis
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Re: Fusel side draw experiment

Post by fanusvdv » Fri Feb 08, 2019 12:37 am

Hi Edwin
Reading this got me thinking about something that I could not explain while doing a stripping run. My column is about 1200mm x 40mm I guess that would be 4 foot high by 1 1/2 inch with no packing or cooling in the column.
I ran the still with the product exit tube below the liquid level in the collection jar. I wanted to see what happens if the condenser runs in a slight vacuum caused by the shrinking vapors to condensate.
So the first thing that I observed was that I was getting lower than usual ABV. I was expecting 70% and getting 60% ABV on the first Jar, about 4 liters, but it being a stripping run I continued with the experiment as it seemed that the product was flowing a bit faster than usual.
When changing jars and the vacuum is broken it takes the still about 2 to 3 minutes to start producing again. My thoughts on this was some cool air gets sucked into the column and needs to heat up again. Now this may need some more thinking but the point that I'm getting at is what happened at the end of the run.
The last jar of the run was at 30% ABV so basically all tails, but crystal clear and very little tails smell.
At that time I did not know why this happened and now it makes me think that the small vacuum or very low pressure in the column might have prevented the fusel to reach the top of the column.
I also use quite a bit of backset for my next ferment and now realize that if I do that again I should run the still a bit longer and as fast as possible with some insulation on the column, after the final jar without a vacuum to discard the concentrated fusel and not have it in my next ferment.

This is all speculation but if it it is true, it may be used to concentrate the fusels a bit better for your take off point.
I'm not sure how much of an effect the specific dimensions of my still have on this?
I hope this observation will help to feed the collective brain a bit, we home distillers do not ask for much besides making the best f@cking alcohol in the world and getting better at it all the time.
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