How I Run My VM/LM Still

[Lester]

Thank you for all your inputs, much appreciated. I am by no means an expert on distillation, having gone into this activity for only 4 months..... and 2 of those months were spent in building my still. I have a lot to learn. Just putting forward my observations.

Initial trial of the reboiler concept (the first version) shouwed evidence of fusel oils floating on top of the distillate. See the 12th post on this thread, 2nd paragraph: http://homedistiller.org/forum/viewtopi ... =1&t=43653
The liquid level marks looked like somebody drew several circumferential lines on the inside of the vessel. Sorry no picture.
Since the oils float on top then it follows that they will be the first ones to get discarded when the shallow reboiler (rev 1) overflows, so there's no need for a dedicated drain for the fusel oils. Rev 1 reboiler is what I have now.

Over the course of 2 months' time I have produced more than 50 liters of 40% ABV vodka and those are all gone by now, consumed already by myself, relatives, visitors, friends, friends of friends, etc. Indeed there were people among this crowd who sampled my vodka and were actually amazed (they told me so) that they can drink again! These were the ones who had stopped drinking because they get nasty headaches from commercial spirits, yet none from my vodka. I hear you Maritimer, I know what you are talking about.

I actually went into this hobby because I have my own share of the-day-after syndrome: Pain in my eyes, shaky hands, upset stomach, high blood pressure, palpitations, etc. Yet I get none of these from what I make at home! I am perfectly useable the following day.

I don't really know if I have perfectly good neutrals but not a few have compared my vodka with imported ones like Abso___ & Smir____ and they prefer mine by a long shot. We usually take it on the rocks or sometimes with buco juice (coconut water).

[Lester]

This taste smearing does not happen on fairly neutral washes, but it does on taste rich washes.

I make vodka using neutral washes (rice-bran or my own panela neutral), and the column was built for neutral. It doesn't make sense (to me) to use taste rich washes for making neutrals.

For those contemplating on using the proportional splitting head as a pot still, I think this saves you the trouble of having to block off the vapor vent in a regular VM. With the proportional splitting head you just slide the valve for zero reflux and you're in pot still mode already.

[flyingdutchman]

Some random thoughts.

Odin: On heads: I wouldn't take them out at a fast rate, but at a slow rate. Two to three drips per second for perfect compaction.

(and the same goes for your foreshots and tails)
I would agree and this is why. Heads most likely have ethyl acetate (EtOAc) as a major component as indicted by others posts (by GCMS).
MeOH.... BP(Boiling Point ) = 64.7 °C @ STP and LHV (latent Heat of vaporization) = 35.3 kJ/mol
EtOAc ....BP = 77.1 °C @ STP and LHV = 31.94 kJ/mol
EtOH ....BP = 78.37 @STP and LHV = 38.56 kJ/mol
It is well established that running a fractionating column slower gives a far better separation. This is especially important when dealing with compounds that have close boiling points because they are harder to effectively separate. So I believe you need a greater number of theoretical plates to get a good separation when compared to say just water and ethanol.

The reboiler.

Odin: what I see is this: reflux exciting your boiler will have a higher abv than the wash or low wines you are distilling.

I suspect it is catching distillate dripping downward from the column. If so it then prevents it from dumping back into the boiler charge. If this is distillate dripping back from the column then it should be of a higher ABV than the boiler charge. My thinking is that vapor leaving the boiler has effectively undergone 1 plate of separation (not even counting any effect of the above packing). Now if it were reintroduced back to the boiler charge it needs to be separated a second time. I believe This would be far less efficient than your current setup.

The Packing,
If I read correctly you have a 4 foot column so I am guessing you have ~ 48" of packing. That may be more than most members here run. Now as you decrease your RR I suspect your HETP then increases. Having an extra ~12" of packing on an insulated column may help with this.

Just my thoughts and not necessarily right

ps you might find this interesting
http://homedistiller.org/forum/viewtopi ... =1&t=12350

[Cardinalbags]

I very much enjoyed reading your post Odin.

On positive feedback: what I see is this: reflux exciting your boiler will have a higher abv than the wash or low wines you are distilling. If you re-distill them and have the gasses re-enter the column from there, you will introduce higher abv gasses into your column, thus creating a positive feedback which is good.

On gathering tails: re-distilling many times means that, with every re-distillation, tailsy alcs are more and more pushed down, towards the end of the column, where they may stack. If you have the reflux exiting (yet exciting) return to the boiler, the tailsy molecules get mixed in with the wash, which is a bigger dilution factor than collecting them in the re-distillation boiler. If you collect them there, they will give you more smearing of tails earlier in the run, especially when using a non-SPP packing. Other than SPP packing just does not give enough re-distillations to keep them at bay.

I have to agree, stacking of the tailsy components would happen. Lester mentioned seeing some fusel oils floating with rev 0 of the reboiler, and the shorter reboiler rev1 or two is just giving a smaller reservoir of higher abv product to draw from, not eliminating the tailsy product..... just less overall tails to contaminate on the amount going back up the column.

Temperature in the column is not a good indicator for when tails arrive. Not in your (or mine) approach. With the efficiency boost from the re-distiller under your column and/or with SPP it is (probably) very easy to take any wash abv to 95%. I do not use a re-distiller under my column, but I do use SPP. By upping the RR I can take a 1% wash to 95%+ without any problems. So if I distill a 30% low wines, I can keep the temperature at (say) 78.3 C all the time. Yet ... in the end tails will come over. The more you compact heads and tails, the smaller these factions become. But there is a trade off. And that's that the tastes associated with these factions do blend into your hearts. Good if you want to make a whiskey or brandy, but not good if you want to make a neutral.

I suppose that is a factor of packing efficiency and how well the stacking of fractions is occurring, especially with low wines as a starting point. As I have improved my packing efficiency, i have found that the onset of temperature rise is later and more severe. i.e. the tenth of a degree rise is followed in the next few 100ml by degrees in temp rise... and a definite swing in taste to the tails. I have found my hearts to be cleaner tasting in the last of the hearts jars next to the tails jars than in previous setups. Now I should have prefaced that by noting I am running Birdwatchers sugar washes for neutrals.....

Another trade off is speed versus purity versus number of re-distillations. If you distill faster at a given number of re-distillations, your hearts will become less pure. Upping the number of re-distillations is the way to compensate for higher gass speeds in the column. That's why using SPP would be your next logical step indeed.

On the re-distillation boiler, re-distilling reflux exiting the column ... is it possible to make a small drain from that? If you take off a few mls after every re-distillation, you will probably get rid of very concentrated tails during the second half of the run.

Just giving it my 2 cents.

Odin.

PS: your numbers of 3.7 liters per hour on a 30 to 40% wash are very good. Given the amount of re-distillations scrubbers give you, I can imagine that it does compromize purity. With the gass speeds associated with the take-off speed you have, you pretty much need to triple the amount of re-distillations not to have smearing. In using 2 kw, I get 3.5 liter per hour out of an 2 incher as well. That's on a 30% low wines charge. If I up the power to 2.8 kw, I can breech 4.5 liters per hour. If I do this, I also make sure there is more reflux going down the column for more re-distillations (closer to 60 on a 120 centimeter of packing).

This is why I have focused more on packing efficiency than worrying about the reflux ratios. If the packing is not up to the task, then increased reflux ratios wont help as much. I would like to try SPP sometime for the fun of it.

I have been using copper mesh and made a very dense packing out of it by rolling it as tight as I could and getting it into the column. I was concerned before the first run as I was sure it was too tight and I might get flooding or vapour channelling due to increased vapour velocity.

I have been otherwise pleasantly surprised. I am running 2"x36 packed section at 2.6-2.8 kW and pulling 4.1litres at the beginning of the run on a 40% low wines charge on the VM takeoff. I am very happy to say the least. My total time for the run on a 26 litre charge from cold start to finished is less than 5 hours. It could be quicker, but I shoot for good heads compression on the front end with my LM head and go slow on the fores draw.

[Lester]

I suspect it is catching distillate dripping downward from the column.....

No need to speculate. The reboiler was placed there to deliberately catch the drippings from the column, and this has already been confirmed by the first experiment.

...... and the shorter reboiler rev1 or two is just giving a smaller reservoir of higher abv product to draw from, not eliminating the tailsy product.....

I am inclined to believe that the oil molecules cling to each other inside the column, slowly making its way to the bottom, then fall as one drop and float on top of the distillate. The reboiler does overflow during stabilization of the column (lots of reflux), and since the oils are afloat (stare at a bowl of greasy soup to see what they look like) they will be the first ones to get discarded during overflow. A bowl that's overflowing is like skimming or raking the oil from the top.........

So I'm not sure how you can say that the reboiler is not eliminating the tailsy product.

[Cardinalbags]

i agree that some of the fusels will overflow, but they can also be saturated in the liquid. You are boiling off liquid from the reboiler and a portion of the reboiled liquid will contain a high concentration of heavier compounds than the liquid boiling from the remainder of the boiler.

Is the higher ABV going back up the column with a higher concentrationof tails a better trade off than increasing packing efficiency and still getting high abv neutral takeoff? The answer is in the eye ofe the beholder as they say.

[Maritimer]

Hi Lester,

Well, sounds like you've done the purity test with your friends and relatives. QC = Pass


Hi Jackson,

Here is another analysis where I take into account the cooling of the condensate. It is very minor compared to the LHV.

These are from my thread on VM analyses, where they seem to have been truncated to one page, so here they are again:

measuring product rate 2.pdf

(157.08 KiB) Downloaded 148 times

Revised RR calculation.pdf

(179.96 KiB) Downloaded 160 times

M

[Lester]

Temperature in the column is not a good indicator for when tails arrive.

Temperature has been a very good indicator for me, this is my experience. And I attribute that to the fast response time of my temperature probes.

Try this as a test: Breathe onto the probe of your thermometer and see if the reading will change and by how much. A light breath on my probe will swing my thermometer needle to full scale in less than 2 seconds. Just one breath.

Now if your thermometer's response time is slow then the tails will be already in your product before your thermometer can even register a temperature change. If that's the case then it's the thermometer, not the temperature. Vapor temperature change is almost instantaneous (low mass), thermometers have a hard time catching up (relatively much much more mass than vapor).

My thermometers are fast and they give me good response times.

I do know what tails smell like. They are the single most obnoxious scent (for me) I can discern during distillation. I can tell if there are tails in my product.

[Lester]

i agree that some of the fusels will overflow, but they can also be saturated in the liquid. You are boiling off liquid from the reboiler and a portion of the reboiled liquid will contain a high concentration of heavier compounds than the liquid boiling from the remainder of the boiler.

Forgive me, but I don't see how we can cheat nature and buoyancy with what we're doing. Oils float on water, plus, water and oil are not miscible, therefore, you can't have a saturated solution using oil and water. What am I missing here?

Is the higher ABV going back up the column with a higher concentration of tails a better trade off than increasing packing efficiency and still getting high abv neutral takeoff? The answer is in the eye ofe the beholder as they say.

No need to trade off anything. I will try to use both to my advantage. SPP coming soon.

[Odin]

Lester,

Fusil oils are not oils, they are higher boiling point alcohols. They dissolve in water/ethanol mixtures. Complete separation only occurs at abv's of 17% and lower. Estimating your general reboiler alc content is higher than that, you seeing oilsy films and residu can only mean my idea that your set-up is collecting and feeding higher bp alcs to the column is right. For these higher bp alcs to get out of solution, must mean there is an abbundance of them.

Om temp probes: I use ultra fast professional grade ones. The reason temp is not a good indicator for tails in your case has everything to do with your set-up and the way you run it.

1. Without SPP you just do not get enough re-distillations to prevent heavier alcohols entering your hearts.
2. Lowering RR makes this even more a problem, since those heavy molecules only find gasses in their way. Nothing stopping them. So they will fly by and enter your product.

Temps go up if higher than ethanol bp alcs come over. But distilling at your power input, with low RR, some of those will always come over and compromise your original reading during hearts.

My advice to you would be threefold:
1. Start using SPP as soon as you can;
2. Use a max RR of 1:2 for enough reflux to take advantage of SPP's upped performance under semi-aquatic circumstances;
3. Connect a drain to the reboiler to bleed off accumulated tails. Use it as a tails trap.

Odin.

[Lester]

Thanks for setting me straight Odin.

I hope you don't mind some questions:

Complete separation only occurs at abv's of 17% and lower.

1. Does this mean that we can no longer remove fusel alcohols from 30% low wines?

2. Assuming there's enough reflux; what happens to fusel alcohols inside the column where EtOH concentration is ALWAYS more than 17% ? Is the column unable to separate low BP alcohols from high BP alcohols?

3. Connect a drain to the reboiler to bleed off accumulated tails. Use it as a tails trap.

What if the drain is on the column, but keep the reboiler in place without a drain? It seems it will be a nightmare to operate a tails trap, not knowing when to open or close the valve, and how much liquid to remove. With this in mind, it seems removing the reboiler is the sensible thing to do (one less valve to operate & no mistakes during the run). hmmmm....

BTW, I'm not being stubborn, just trying to understand the chemistry. It would be hard for me to act upon anything without first acquiring a thorough understanding.

[Odin]

Sorry if I am a bit of a pain in the ass right now. Typing is very difficult due to surgery to my finger, yesterday, so no 400 tabs per minute and difficult to make a long story, but I want to answer, because I like this tread very much!

1. What I mean is: fusils - in normal amounts - come out of solution at 17%. Above that % they stay dissolved in the drink and should not stain. So yes you can get rid of them by re-distilling, since they are heavier. First go the lighter, lower bp alcs, then ethanol, then the tails/fusil oils. But some smearing always is there. Vision: you standing in a basketball field with a 2 meter fence around it. Lots of balls on the ground. Tennis balls, soccer balls, basket ball balls. You throw them in the air with a certain energy/power input. Most of the Tennis balls will go out first (heads), some soccer balls (hearts), a few basket balls as well (tails). Now you up the power input as you do. You throw harder. Now more basketball balls come over the fence. More contamination of tails in your hearts. Now imagine you make the fence higher to compensate. And build a small platform half way up, to collect balls that fell down and didn't make it over the fence. To be thrown from that half way up platform a bit later. Okay, you throw harder, fence is higher, most of the tennis balls (heads) are already out, so now ... most of the soccer balls (hearts) make it over the fence), but most of the basket ball balls you randomly pick up do not. They land on the platform (aka re-boiler). So ... by the time you feel like emptying that platform and tossing balls collected over there over the fence ... what kind of balls do you throw over? Tails.

2. In the beginning of the run they are pushed out of the column and back into the boiler. When most of the alcohol is depleted, that's when the concetration (relative) of fusils in the boiler is biggest. More may assemble in the lower part of the column. And if you put in a lot of power, many will make it "over the fence". So there's two things you can do: lower the power (on a potstill - aka throw with less energy) or up the RR (Reflux Ratio aka Return Ratio - higher the fence). Every re-distillation makes it harder for heavier components (in combination with ligter elements) to make it all the way up.

3. I know Edwin is a fan of that idea. I am not. I feel that a normally operated column (without your reboiler) does not need it. When fusils come into play, finish the run. Especially on your approach and especially with SPP, a tails bleed is not needed. In fact I think a boiling ball under an SPP packed column is not needed, since with SPP, it is most functional in an aquatic environment. Where are the most liquids assembling? At the top, where you "make" the reflux. And in the first centimeter of packing, where low abv is redisstilled, giving up most of its water. Place a bubble cap there, and what will you be feeding to the column? Higher abv, so less water to be refluxed out of it, so less efficiency of a packing that would otherwise give you (in that first centimeter) around 2 re-distillations. The only reason I propose a bleed is because of your design, which has benefits, but is (see point 1) a tails trapp and that you don't want.

Hope this makes sense.
Odin.

[Lester]

That's a great analogy Odin! Very easy to understand!

In terms of fusel alcohols, I would just like to point out the similarities bewtween this reboiler and the lowermost plate on a plated column. Both of them work in almost the same way. Yet I didn't read any discussion highlighting the bubble plate as a concentrator of fusel alcohols anywhere in this forum. Maybe I will find the thread eventually.

If you would please take time and look at this graph taken from the reboiler thread. This was from an actual run of (IIRC) rice bran wash. The temperatures were manually recorded during the run then converted to % alcohol. You can see that the reboiler accumulates & depletes of alcohol as the run progresses. During the last half of the run the % alcohol in the reboiler was always <17%. Meaning, the fusel oils fall out of solution and clump together and float on top. On reboiler rev 1 these oils get discarded when the reboiler overflows, which happens during max reflux.

Again I submit the evidence of the first experiment. If the oils are in suspension then it follows that there won't be any liquid level marks, and yet I saw 4 marks on the reboiler (rev 0)after the run. These marks were formed by the oils because they were floating on top of the distillate. If the oils were in suspension there would be no marks.

I believe my practice of converting temperature to % alcohol is an accepted industry standard (Ebulliometer concept), although Dad300 does not agree.

But first...thermometers and temperature, do not tell you the purity of your alcohol. Nor do alcoholometers.

I don't want to stress you Odin, please take time and get well. It's just that these evidences can not be ignored if we are to arrive at a correct understanding of the chemistry invovled, even if it departs from conventional wisdom. Sorry to hear about your finger surgery.

[Maritimer]

Hi Lester,

I would agree with DAD on that one. After the heads cut, the next 1/2 litre might or might not give me a headache, even though the alcoholometer says I've got azeo. The amount of impurity is too small to be seen by the alcoholometer.

I've been looking at your thermometer, and I'm thinking of using it to measure vapour temperature. You say you wrapped it in PTFE tape. I use that tape on the joins in my column--I don't have tri-clamps, I just insert the sections of the column into couplings. The tape gets rather stringy and disintegrated, so I put a few turns of electrical tape over it. I'm wondering if you get the same effect, and if so, does vapour get to the diodes? I don't think vapour on the diodes would matter very much. They are forward-biased, so have low resistance and pure ethanol vapour has very low conductance (and probably water vapour, too). And even if a very high resistance is in parallel with the diode, its voltage wouldn't change much. Thoughts?

M

[DAD300]

Maritimer....alcoholometers don't read just ethanol. It's just a hydrometer with an alcohol scale in it.

If you drop an alcoholometer into a tube of pure/straight acetone, it will sink and read 96+.

My fores and all the heads will always read 96%.

[Maritimer]

Yup, DAD, I agree.

Yes, the instrument reads specific gravity. Anything that has the SG of ethanol will look like ethanol.

Methanol has a density of 0.791 g/cm^3. Ethanol has a density of 0.789 g/cm^3, which is only 0.2% different, so it would be hard to tell them apart with an alcoholometer.

Edit: A-ha, so that is why they use methanol to adulterate ethanol!

Methanol boils at 64.7*C and ethanol at 78.2*C, so it would be easy to tell them apart by boiling point.

My point is that in either case, if there is just a smidgen of methanol in the ethanol (enough to give me a headache), neither technique (except very high precision equipment) would be able to see the methanol. Mmmm, which brings us back to Lester's thermometer...

M

[Edwin Croissant]

Just my 2 cents on the subject.

Remember the coefficient k from this post? For a water ethanol mixture with a small amount of amyl alcohol (one of the fusel oils) the coefficient k for the amyl alcohol is:

• 20 at 10% ABV (there is 20 times more amyl alcohol in the vapor then in the liquid)

• 2 at 40% ABV (there is 2 times more amyl alcohol in the vapor then in the liquid)

• 0.2 at 90% ABV (there is 1/5 the amount of amyl alcohol in the vapor then in the liquid)

For amyl alcohol the azeotrope is at about 54% ABV.

So (bad analogy) amyl alcohol in a column behaves like a helium balloon. When released it is lighter than air and goes up until it has the same density as the surrounding air. Hoist the balloon higher and it will decent after release. At the end of the 19th century it was discovered that the highest concentration in a column occurred where the coefficient k of ethanol and amyl alcohol are the same and that is at about 40% ABV.

From the viewpoint of the amyl alcohol the column is a trap. It is forced in with no way out, until the column is saturated and it is forced through.

How to prevent this:

• Flush the amyl alcohol continuously out with extra reflux. Take-off rate is greatly reduced

• Make room for the amyl alcohol at 40% ABV, mount a bubble ball under your column

• Make a take-off at 40% ABV

• Repeatedly flush the amyl alcohol out of the column

You are doing the last option manually. Amyl alcohol raises the boiling point. So when it seep through the temperature goes up and you go into full reflux, flushing the amyl alcohol out of the column. This is something that can be automated quite easily as the iStill showes.

Now just a thought. Why dump the content of the column back into the boiler? When you dump the content in another vessel you take the amyl alcohol (fusel oil) out of the system. This will increase the interval between flushing. I think that the ethanol can be recovered by mixing with cold water and decanting the fusel oil. Collect the fusel oil, a full barrel will make good money

[Lester]

Hi Lester,

I would agree with DAD on that one. After the heads cut, the next 1/2 litre might or might not give me a headache, even though the alcoholometer says I've got azeo. The amount of impurity is too small to be seen by the alcoholometer.

I've been looking at your thermometer, and I'm thinking of using it to measure vapour temperature. You say you wrapped it in PTFE tape. I use that tape on the joins in my column--I don't have tri-clamps, I just insert the sections of the column into couplings. The tape gets rather stringy and disintegrated, so I put a few turns of electrical tape over it. I'm wondering if you get the same effect, and if so, does vapour get to the diodes? I don't think vapour on the diodes would matter very much. They are forward-biased, so have low resistance and pure ethanol vapour has very low conductance (and probably water vapour, too). And even if a very high resistance is in parallel with the diode, its voltage wouldn't change much. Thoughts?

M

When taking out the heads I do see the temp rise as I get out of the heads. This temp change, plus tasting the product, tells when I am definitely out of the heads. I use the thermometer as a tool and as with all tools you have to know how to use it properly, and not to expect too much from it. Now that you put it that way then I agree with Dad also.

I will answer your questions about the diodes in the thermometer thread, here:
http://homedistiller.org/forum/viewtopi ... =2&t=43379

[DAD300]

I know it's only one issue. But, you guys better stop it. I know it's Friday and all, but you make me blush!

But, alcoholometers don't read purity. If you drop an alcoholometer in to a flask of pure acetone it will read above 96%.

Please join me at http://homedistiller.org/forum/viewtopi ... =2&t=45041

[flyingdutchman]

I have to agree that we can not state purity based on liquid density nor the liquid temperature. Here are just some of the components found in a scotch whiskey
Acetaldehyde, Ethyl acetate, Diacetyl, Methanol, Propanol, Isobutanol, Amyl alcohol, Iso-amyl alcohol, Furfural.
Here is an analysis by GCMS of a vodka
http://homedistiller.org/forum/viewtopic.php?f=1&t=6749
Yes in large quantities it would have a discernable effect on the BP or a density reading but I do not believe that this is the case in smaller quantities (mg/L).

PS
We call them fusel oils but I believe they are alcohols and each have different BP's and solubility's in water. The solubility might also perhaps change depending with the water temperature. Such as propanol (BP~98C ) which is completely miscible in water, or amyl alcohol (2-Methyl-1-butanol) (BP ~128C, sol: 31g/Liter). So I think we need to be careful in assuming that all fusel oils separate out of solution at 17% ethanol. I think it depends on the type of fusel alcohol, the amount , the co-solvents present(like ethanol), as well as perhaps temperature.

[Odin]

17% is a nice standard to start with. Based on research by the University of Edinburg on whisky. A starting point can always be refined, off course ...

Odin.

[flyingdutchman]

Hi Odin,
I don't doubt that is true. I just mean to say there are other factors which influence solubility.

[Odin]

You bet!

Odin.

[flyingdutchman]

For instance since the propyl alcohols are completely miscible with water, odds are they never drop out of solution.
The amyl alcohols (longer greasier alcohols )are a different story. Still I never see them drop out of solution in my wash's (lower ABV). I don't usually see them drop out of solution in the stripped runs (but what if it gets too cold in the basement?).
Yet we put them in the still and concentrate them towards the end of the run in say Lester's reboiler or on the lower plates of some plated column and they separate out of solution. No doubt the amount of ethanol plays an important part (as a co-solvent) and above 17% they are far more likely to stay in solution. But also perhaps its their inherent solubility (or lack of) and fact that they were concentrated (in the reboiler) above some number of grams per liter that is also plays a role.

[Maritimer]

I'm intrigued by that idea of putting a take-off at the bottom of the column, maybe something like a slant-plate boka with a needle valve. Tell me, you chemistry guys, is this a good idea? What would come out of it? How would it be manipulated? Or would it just waste ethanol? I have a conventional VM, except that it is insulated to have virtually no column, gate valve, and product liebig descender heat loss.

M

[DAD300]

Could this idea of a catch at the bottom of a column, be what the guys with bubble balls or a single bubble cap get?

[Lester]

That behavior of Amyl alcohol inside the column is very interesting Edwin. It does make sense that we should be removing Amyl when the concentration is greatest, at 40% as you mentioned. We lose less EtOH this way, rather than forcing it out slowly at 95% ABV when the Amyl keeps trying to fight its way back inside the column.

Is there anybody here on HD doing this right now? I'd be interested to hear his comments!!!

[flyingdutchman]

Well Hats off to Edwin he had exactly the image I was looking for, here is his post,http://homedistiller.org/forum/viewtopi ... =1&t=42227
Mind you its probably a continuous still so my belief is we are talking about an ever greater concentrating effect as they run more and more wash through it. As Odin points out its probably a lot more common in continuous stills!
However notice the various types of "heavier" Lower BP fusel alcohol seem to concentrate on the lower plates. And the "lighter" more volatile of the fusel oils (propyl alcohols) are on the higher up (lower) plates.
DOH: I just saw Edwins post about volatility with respect the % ethanol so it would appear that this plays a much more important role than just a simple BP !

But then its all on the lower plates. Does this happen on our stills on the lower plates or bottom boil ball or just plain the lower packing? I believe so but have no personal proof of it. Yet look at Lester's reboiler it seem to support it.

[Lester]

As far as Edwin's thread is concerned, it seems experimentation is in order. I'd be willing to hack my column in the name of science!

Anybody care to do a Design of Experiments (DoE) so we don't stray too far from each other?


Edwin,
From your research, what would be the best TEMPERATURE (hello Dad300!) to bleed off the Amyl Alcohol/EtOH/water mixture? There's no other indicator for when and where to bleed off so we have to do it by temperature, and possibly smell. This time we use temperature as an indicator for impurity, not purity. (No way I'm gonna taste that nasty stuff.)

[DAD300]

Oh...trying to define a vapor by temperature...

Now, I've read Edwin's post and I still ask, rather than bleed the fusels off, what about trapping them in a bubble plate at the bottom? Or does that just continue to smear them across the distillation?