Spiral Pot Riser

Simple pot still distillation and construction with or without a thumper.

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raketemensch
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Re: Spiral Pot Riser

Post by raketemensch »

So an extra 10% ABV with the horizontal coil? Interesting.

Any noticeable flavor differences?
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Re: Spiral Pot Riser

Post by MichiganCornhusker »

Kareltje wrote:Wow!!!!
I thought I was original, but someone has already thought the same things.
Ha, I thought the same thing.
I've been kicking the idea of a non-linear condenser around for a while, and of course it's already been done here.

Thanks for bumping this thread, very interesting.
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Kareltje
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Re: Spiral Pot Riser

Post by Kareltje »

raketemensch wrote:So an extra 10% ABV with the horizontal coil? Interesting.

Any noticeable flavor differences?
Sorry, I have a bad taste. That is to say: my tongue and nose are not very good in discerning differences in flavour or taste.

The horizontal spiral seems to react slightly different with the vertical spiral. But that is very hard to describe exact, because my own behaviour is different too and the gas burner is not very precise.
I made the vertical spiral just because a pipe of 2 m did not fit under my ceiling and what goes up 2 m, must come down 2 m too.
Cooling the upper part of the spiral with a damp cloth also raises the % ABV.
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Kareltje
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Re: Spiral Pot Riser

Post by Kareltje »

MichiganCornhusker wrote:
Kareltje wrote:Wow!!!!
I thought I was original, but someone has already thought the same things.
Ha, I thought the same thing.
I've been kicking the idea of a non-linear condenser around for a while, and of course it's already been done here.

Thanks for bumping this thread, very interesting.
I would like to have a 15 mm OD inside a 22 mm OD pipe and then bend it together. But I am not sure this will work well.
Knowing myself, I think I am going to try it anyway, soon.
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Kareltje
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Re: Spiral Pot Riser

Post by Kareltje »

Yesterday I did another run: 7 ltr of a measured 42 %ABV, which after the run turned out to be 43,6 % ABV.
All collected heads and tails, so I decided to run as slow as possible to make large cuts and get a clean middle.
I took samples and got this graph.

Image

This time I calculated the mean time and % of a sample. (As opposed to the former graphs where I took end time and %!!)

I ran with the valve at the lowest possible position and kept it that way all the time. So apart from the differences in the gassupply via the national grid, the still ran at a constant heat.
As expected it started at 91 %ABV, but to my surprise it stayed there very long!
From the resulting flow of distillate I could calculate how much heat was regained in the condensing and I could compare this to the heat from the stove. It turned out that the distillate took from 27 % down to 11 % of the heatinflux. Which means that the heat loss between burner and top of the system grew from 73 to 89 %.
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Re: Spiral Pot Riser

Post by eStill »

How do you know it started at 91%? Is this measured or calculated? It's too high. I wouldn't drink it. If measured, did you adjust your %ABV for the temperature of the distillate?

Did you use a turbo yeast and a lot of extra nutrient?
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Re: Spiral Pot Riser

Post by rad14701 »

eStill wrote:How do you know it started at 91%? Is this measured or calculated? It's too high. I wouldn't drink it. If measured, did you adjust your %ABV for the temperature of the distillate?

Did you use a turbo yeast and a lot of extra nutrient?
That 91% spirit was distilled from 43.6% low wines as stated above, not from wash...
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Re: Spiral Pot Riser

Post by Kareltje »

Last week I did a few more runs: one rumwash of about 12 %ABV and two low wines of about 32 %ABV. I drawed (drew?) the lines of x (%ABV fluid) and y (%ABV vapour=distillate) like the standard graph of liquid-vapour-equilibrium, only changed the colours.

Image
So vertical the degr C, horizontal the %ABV. Note that my thermometer is a bit off: 98,5 degr. C is really 100 degr C. I think that 78,5 degr C is really 78,75, but I am not sure about that.
The three recent runs I did with a slow start, to get rid of the nasties in the heads. After that I ran at my normal speed.

It is clear that in the runs at normal speed there is a good correspondence between temperature and %ABV of the vapour and so the distillate. The difference between % in fluid and % in distillate gives an impression of the effect of my spiral riser. (15 mm OD and 2 m length). 12 % becomes 75 %, 32 % becomes 90 %.

I still do not understand the strange result of the first run (spiraal) at the lowest speed. A vapour of 45 %ABV at 88 degr C is inconcievable to me.
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Re: Spiral Pot Riser

Post by Alchemist75 »

I've noticed that when using a spiral riser that as I approach the tail of my run the drip rate starts to fall gradually while the ethanol proof seems to actually creep up a bit and then once it runs out condensate of any sort just stops flowing, dead. My copper packed passive reflux head ends the run exactly the same way except that it flattens the run at a steady proof from start to finish as well as pinning the fusels in the boiler. My theory is that as the last of the ethanol comes up through the spiral the vapor speed drops. The fusels and water have a much harder time making through the air cooled spiral without dropping back to the boiler. I'd say the spiral literally makes the run good to the last drop....
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Re: Spiral Pot Riser

Post by Kareltje »

You are a keen observer! :clap:
I never looked at the tails in such detail.

My spiral riser behaves differently from a packed column I once used to use, but that is a feeling, not supported by measurements. The spiral has an ID of only 13 mm, the packed riser had 28 mm. At the same rate of heating the vapourspeed in the spiral is much higher than in the column AND it is not disturbed.
At the lowest position of the gasvalve I got just not 78 dgr C in the top of the column, but the vapour is pushed through the spiral unless I cool it with damp cloth. Oh, and maybe not insulating the boiler and fill it just to 50 % might help, did not try that yet.

In trying to find an explanation for something I noticed I stumbled upon the volume of vapour/volume of fluid. One litre of fluid water makes 1.243 litres of vapour, while 1 litre of fluid ethanol only makes 383 litres of vapour, only about 1/3! So I can imagine that the condensation of water creates a kind of underpressure and more so when there is more water in the mixture.
While formulating this sentence I got a light! :idea: This might just be my solution!!
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Re: Spiral Pot Riser

Post by Kareltje »

MichiganCornhusker wrote:
Kareltje wrote:Wow!!!!
I thought I was original, but someone has already thought the same things.
Ha, I thought the same thing.
I've been kicking the idea of a non-linear condenser around for a while, and of course it's already been done here.

Thanks for bumping this thread, very interesting.
Thumping it again. (Well: Alchemist did.)
I did try bend a 15 in 22 mm pipe.
2016-10-20000aklein.jpg
1 m lenght of 15 mm OD, about 85 cm lenght of 22 mm OD. Kind of annealed on a wood fire.
2016-10-21000bklein.jpg
Halfway bending. Wanted to make -O- , but 1 m length turned out to be too short.
2016-10-21001a.jpg
The result after adding the couplings. Both vapour way and waterway can be blown without resistance. The bending turned out to be rather clumsy, with bumps and dents. What is worse: it is difficult to find a point of equilibrium or to position it so, that the flow of condens will be steady downward. Did not use it, until now. :angel:
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Re: Spiral Pot Riser

Post by Alchemist75 »

Well it's rather easier to observe what's happening when I can actually see it occurring within my system :wink: .
I can see when reflux is occurring in the refluxer, watch it dropping back to the boiler and how that corresponds to the behavior of the condensing gasses in the condenser and of course the drip rate....
Passive reflux makes for interesting study.
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Re: Spiral Pot Riser

Post by Kareltje »

Alchemist75 wrote:Well it's rather easier to observe what's happening when I can actually see it occurring within my system :wink: .
I can see when reflux is occurring in the refluxer, watch it dropping back to the boiler and how that corresponds to the behavior of the condensing gasses in the condenser and of course the drip rate....
Passive reflux makes for interesting study.
Ah, you make me jealous! I bought a glass still, did not unpack it yet. Have to find a safe place to park it and make a stand for the condenser.

May I ask you: do you have a spiral cooler, that is cooled in the air?
I often use a ss cooling spiral that sits in the plain air. About 7 m long and I regulate the heat input so that maximum 6 m of the spiral is hot and the rest is warm.
When I let the boiler run, the heat wil gradually crawl backwards from 6 m to 5, 4 etc., while the %ABV gradually drops and the volume/min slowly drops. When I let it run, it ends at 0 m hot, 0 %ABV and (almost) 0 ml/min.
I do not know how to explain that, because the heatinput in the boiler stays the same during the whole run, so should the dissipation through the condensation in the spiral.
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Re: Spiral Pot Riser

Post by Alchemist75 »

Yes it's air cooled. I was going to suggest to you the use of a fan, even on a short coil it'll impact things drastically even to the point of inducing absolute reflux especially if your energy input is relatively low. If I read what you're saying here correctly you're observing the same or similar phenomena as I have with mine where it basically slows to a stand still at the end of the run.(?)
I think it's because as the ethanol boils off of mixture in the boiler the liquids boiling point starts to increase thus giving lower vapor speed at the same temp. That leads to a state of absolute reflux. Is that what you're talking about?
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Re: Spiral Pot Riser

Post by Kareltje »

Alchemist75 wrote:Yes it's air cooled. I was going to suggest to you the use of a fan, even on a short coil it'll impact things drastically even to the point of inducing absolute reflux especially if your energy input is relatively low. If I read what you're saying here correctly you're observing the same or similar phenomena as I have with mine where it basically slows to a stand still at the end of the run.(?)
I think it's because as the ethanol boils off of mixture in the boiler the liquids boiling point starts to increase thus giving lower vapor speed at the same temp. That leads to a state of absolute reflux. Is that what you're talking about?
You seem to describe my observations, indeed. :thumbup:
Do not have a fan, but I do have wet rags.

The boiling point increases, allright. But does this increase or lower the vapour speed?
(You have a point I did not think of before!)

Frankly speaking: I think about this another time, when sober again. :mrgreen:
Thank you for your contribution!!
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Re: Spiral Pot Riser

Post by Alchemist75 »

It decreases vapor speed. The temperature remains constant in the boiler, the boiling point slowly rises as the ethanol vaporizes away and the water no longer has sufficient energy to make it past the spiral so it condenses and falls back to the boiler thus the drip rate grinds to a halt despite the boiling in the cooker. The base line effect is that the coil or whatever passive/semi passive reflux apparatus is used literally squeezes out the last available amount of ethanol in the wash. I've actually come to prefer using a vertical spiral lyne arm especially for my stripping runs because I pull a better yield. My passive reflux head gets used for my long, slow spirit runs which compresses the cuts and gives a nice proof bump. I don't want a full column because I like to keep flavors but I like the perk that a certain degree of reflux offers. Huzzah hybrids!
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Re: Spiral Pot Riser

Post by Alchemist75 »

One thing I've not attempted that could possibly enhance the reflux capacity of the coil riser would be to add salt to the wash to tweak the boiling points. Not sure if it'd work but I see no harm in trying.....
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Re: Spiral Pot Riser

Post by still_stirrin »

Alchemist75 wrote:One thing I've not attempted that could possibly enhance the reflux capacity of the coil riser would be to add salt to the wash to tweak the boiling points. Not sure if it'd work but I see no harm in trying.....
I wouldn't do it. It won't do what you want it to do.
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Re: Spiral Pot Riser

Post by Alchemist75 »

@still_stirrin:
I've used non iodized table salt in the past without any noticeable result but after I did more research I realized that to get an appreciable change in boiling points I needed to use considerably more than I had before. Now, maybe you can explain to me if the presence of salt affects the boiling point of the ethanol as well. The way I've seen it explained only ever states that is raises the boiling point of the water but no discussion of how it affects the alcohol. Do you have insight here?
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Re: Spiral Pot Riser

Post by Kareltje »

It was surprisingly simple, after all! Once I put aside my fixed thinking and started anew.

Suppose you start running a wash of 40 %ABV. Then you get a vapour of about 77 %ABV, so when it has condensed, 1000 ml of it consists of 770 ml alcohol and 230 ml water. Before it is condensed, the vapour consists of 770 * 383 = 294.910 ml alcohol and 230 * 1.243 = 285.890 ml water, and it took 770 ml * 664 J/mll = 511.280 J for the alcohol and 230 ml * 2.249 J/ml = 517.270 J for the water. So we have 580,8 l vapour for 1028,55 kJ which makes 0,5647 ml vapour per J.
At the end of the run we have a wash of 0 %, so 1000 ml consists of 0 ml alcohol and 1000 ml water. The volume in vapour is than 1.243.000 ml and it took 2.249.000 J, or 0,5527 ml vapour per J.
So just by keeping the input of heat the same, the amount of vapour formed per minute gets less during the run. Just a few percent, but it does diminish.
Than we have the growing headspace in the boiler during the run. Starting from 5 litres of 12 %ABV I have 5 litres of headspace. At the end I made 1,7 litres of 36 %ABV distillate so I have a headspace of 6,7 litres. So 33 % more room for the vapour.
The coil of my condenser has an ID of 13 mm, so a surface of 1,3273 cm2. One winding has a diameter of 27,5 cm, so a length of 86,39 cm. So the volume of a winding is 114,7 ml. This in turn means that the extra headspace in the boiler is equal to the volume of 14,5 windings.
The third factor is the raising of the temperature. Say we start at 90 dgr C, so 70 K difference with ambient temperature. We of course end at 100 dgr C: 80 K difference. As the loss of heat is proportional with the difference in temperature, this loss will be about 14 % higher at the end compared to the start. We do not know the exact loss, for it depends on the build of the still, but the higher loss points in the same direction as the other two factors.
A fourth factor is the greater reflux that will occur when both the headspace and the heatloss become greater.

This is why the point where the vapour is condensed in my air cooled spiral condenser gradually crawls backwards during a run. As long as the heat input stays the same.
The critical moment of a run is the regulating of the gas at the start of the run. If I am too late, the alcoholic vapour will flow in the air with all the risks. From the moment it is stable, I can be relaxed: from that moment in all parts of the system the alcoholcontent will diminish: boiler, condenser, product.
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Re: Spiral Pot Riser

Post by Alchemist75 »

Wow. Well that's involved but it makes sense. So you're saying here that the slow increase in boiling point theory isn't what's causing the steady rise in reflux or is that just a piece of the puzzle?
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Re: Spiral Pot Riser

Post by Kareltje »

Alchemist75 wrote:Wow. Well that's involved but it makes sense. So you're saying here that the slow increase in boiling point theory isn't what's causing the steady rise in reflux or is that just a piece of the puzzle?
Well, I do not know much about reflux. Only used natural reflux without really knowing it.
And, due to the fact that English is not my mother language, I am not sure what you mean by "slow increase in boiling point theory". Is this a theory based on the fact that the boiling point of the wash slowly increases during the run?
This higher temperature would cause a small increase of the heat loss to the environment. This results in less heat available for revapourizing, so more condensation, so more reflux.

In fact I was only trying to prove I was right in trusting my still after a sound and stable start. But my still is rather unconventional: just a boiler with a gasflame under it and a large spiral cooler hanging in the air. So the limiting factor was the cooling by the ambient air. I was fixed by the idea that the cooling was located in the condenser, and could not understand how the constant input of heat could be lost by a diminishing length of condenser. But that clearly is not the point.
It is not only the amount of heat, but also the amount of vapour that causes the length of the hot part of the cooler.
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Re: Spiral Pot Riser

Post by Alchemist75 »

Right, as the ethanol boils off the wash the boiling point of the remaining wash will slowly creep up. Given that there would be a increase in head space as well, as you pointed out, that would be another variable I hadn't thought about. What I notice as my run progresses is that the amount of condensing vapor in my condenser decreases and it's consistency changes as well which is not something you can observe in a regular metal condenser. I can literally see when the abv% changes in the vapor just by the way it condenses. I can also tell you that at full power, when using a spiral riser, that the abv% of the vapor goes through cycles. The abv increases for a while, then there will be a small surge followed by a lower abv which then creeps up again. This continues until the vapor speed starts to fall near the end of the run at which point you're getting high abv% ethanol at a slow drip rate.....just a little observation I've made. At lower energy input I bet that cycle doesn't occur as there is no flooding occurring in the coil....
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Re: Spiral Pot Riser

Post by Kareltje »

Alchemist75 wrote:Right, as the ethanol boils off the wash the boiling point of the remaining wash will slowly creep up. Given that there would be a increase in head space as well, as you pointed out, that would be another variable I hadn't thought about. What I notice as my run progresses is that the amount of condensing vapor in my condenser decreases and it's consistency changes as well which is not something you can observe in a regular metal condenser. I can literally see when the abv% changes in the vapor just by the way it condenses.
I can not see it, but I think I can feel different shapes and sharpnesses of the border between hot and cooling. Sometimes I see the thermometer moving up and down a few degrees.
I can also tell you that at full power, when using a spiral riser, that the abv% of the vapor goes through cycles. The abv increases for a while, then there will be a small surge followed by a lower abv which then creeps up again. This continues until the vapor speed starts to fall near the end of the run at which point you're getting high abv% ethanol at a slow drip rate.....just a little observation I've made. At lower energy input I bet that cycle doesn't occur as there is no flooding occurring in the coil....
Interesting observations. I have seen some very uncommon things myself, and neglected them. Partly because I could not measure them.
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