Sciencemadness Discussion Board - Moonshiners' 'Thumpers': Myth or Reality?

Nearly pure ethanol comes off if well mixed. As to the how, if you zoomed in on a single bubble of water vapour, water diffuses from the bubble into the alcohol and alcohol diffuses from the liquid into the bubble. When the water vapour enters the liquid at the edge of the bubble, it releases it's enthalpy of vaporisation and this is in turn absorbed by the evaporating ethanol. This continuous until equilibrium is reached (but never quite gets there). But that's not to say that ethanol vapour doesn't also diffuse back into the liquid as well, it is a dynamic system and molecules are constantly zooting too and fro, all the time, the rate of ethanol evaporating is simply large than it condensing and vice versa for water.

[Edited on 17-2-2015 by deltaH]

If you just said that an ethanol vapor bubble will strip more ethanol from the miscible liquid... Yes. That is how a fractional column works, and that is the reason the thumper feed tube is below the liquid level. The bubbles strip more ethanol.

Zombie - 17-2-2015 at 19:12

The heat is supplied by the condensing of the incoming vapor from the still (latent heat). Efficient condensing would be promoted by having a high depth of submergence of the still vapor outlet pipe.

Enrichment of the thumper outlet vapor is based on the vapor-liquid equilibrium (VLE) curve for the system ethanol-water. Enrichment is due to the high relative volatility of alcohol to water in the region of interest, ie, around 20wt% alcohol of the liquid in the thumper. See Zombie's and deltaH's VLE curves.

This has been stated above several times. I'm just trying to say it more succinctly.

In regard to calling people genitals, Conan O'Brien said "what kind of a dick would call a person a vagina?"

[Edited on 17-2-2015 by Magpie]

Agreed!

I didn't see the vid yet tho. Coming back for it.

Zombie - 17-2-2015 at 19:15

The heat of mixing of ethanol and water is exothermic by - 777 J/mol (Wiki), and all mixing is exoentropic.

So both ΔH and ΔG of mixing are negative (< 0).

To separate, that energy must be expended.

The idea that steam coming off the still provides that energy is fallacious. You need to look at the entire system: unheated thumpers simply introduce more heat losses. Insulated ones act like steam pipes.

And heated ones are a little more complicated than one might think. Primary still vapour would have to condensed to just below its BP. Once the thumper is, say, half full, a secondary distillation would be carried out by heating to BP and condensing the thumper vapours. But that wouldn't be a real thumper...

You are still ignoreing the fact that once both pots are at the same opperating temp... As the boiler looses Alch. IT's temp rises, and the heat required to boil the Alch. rich thumper lowers.

Zombie - 17-2-2015 at 19:19

Just saw near the bottom that they offer a two thumpers in series version, was wondering about that. I guess the enrichment effect of a second thumper is probably much smaller than the first?

Yes, you can run up to three thumpers in series if insulated, and reach very near azeotrope.
Thermal losses make it require more energy however than a simple 2 run distillation. Not many fellas will run multiple thumpers UNLESS they are running FREE wood fired stills.

Zombie - 17-2-2015 at 19:21

Every tray is not individually heated though. So how does that work then?

It doesn't have to be. Heat is provided by the boiler. The column itself, in a ideal scenario, operates adiabatically (ΔH = 0). Things constantly condense and re-volatise. At the end you get your energy back in the condenser(s), MINUS what was expended for the separation.

My point with regards of Magpie's Latent Heat is precisely that: condensation occurs and latent heat is released but evaporation also occurs and consumes latent heat.

[Edited on 17-2-2015 by blogfast25]

Your first sentence explained why a thump works.

Zombie - 17-2-2015 at 19:23

Quote: Originally posted by Etaoin Shrdlu

Oh god I'm dying of laughter.

What's also funny is that his refluxer certainly works (despite the pompous name) but does anyone believe his little pickle jar would work? It's certainly hopelessly under-dimensioned, looking at the size of the pot. That thing would fill up in no time!

You are right.

These are built / sold as mis conceptions.

Magpie - 17-2-2015 at 19:25

You are still ignoreing the fact that once both pots are at the same opperating temp... As the boiler looses Alch. IT's temp rises, and the heat required to boil the Alch. rich thumper lowers.

Agreed, and this may be key to the operation. We really should be doing enthalpy balances on the still and thumper using realistic examples. We haven't done that yet.

Zombie - 17-2-2015 at 19:25

Quote: Originally posted by Etaoin Shrdlu

Oh god I'm dying of laughter.

I was under the impression that the liquid level in the thumper doesn't keep increasing post start-up, no?

Mostly correct.
The amount of water vapor coming in is carefully controlled by the heat applied, and the amount of Alch. going out keeps the level fairly constant.

Zombie - 17-2-2015 at 19:28

I was under the impression that the liquid level in the thumper doesn't keep increasing post start-up, no?

But Delta, HOW CAN THAT POSSIBLY BE?? An uncooled pot like that MUST act in part as a condenser, BY DEFINITION, almost!

In part, but the heat losses to the air is small, it doesn't have a large surface area and it's convective cooling which is also not large, compared to a water cooled condenser that is.

I read http://homedistiller.org/equip/designs/thumper to try to answer this issue of the size of the thumper, they make the point that you don't want it too small because the extra alcohol has to come from the volume of what was originally placed there and as it's depleted, it works worse and worse until it has little effect. That makes sense to me, so yes, that jar does look a little small, but then again, it is recommended to use distillate tails to charge it, which would help to have more alcohol in a smaller volume of course.

There's probably an optimal size born out of experience with these things. I'd say it's probably made as large as the tails generated from distillation from a certain sized rig.

1/2 the size of the boiler.

Zombie - 17-2-2015 at 19:30

In part, but the heat losses to the air is small, it doesn't have a large surface area and it's convective cooling which is also not large, compared to a water cooled condenser that is.

Totally subjective. What if you use a fairly large copper thumper on a cold night in the Appalachian Mountains?

The point stands: the thumper MUST fill up, slowly or quickly is fairly irrelevant.

There's probably an optimal size born out of experience with these things. I'd say it's probably made as large as the tails generated from distillation from a certain sized rig.

Look at the designs on the Tinkerwebs: there's no real discernable pattern.

[Edited on 17-2-2015 by blogfast25]

You are correct. This is why Moonshining" has a season.
Some run year round but they either insulate or run in small confined (dangerous) spaces.

Thermal losses ARE important. Even a simple pot still will not run in extreme cold. It all condensates in the cap

blogfast25 - 17-2-2015 at 19:33

Thank you.
Lobster for breakfast! That's awesome. (You are 7-8 hours ahead of me (PST), right?)

And because we're contrarians in this part of the world, I now have to go to bed, stomach full of lobster!

'Hostilities' to resume tomorrow.

Night night. Don't let the thumpers bite.

Zombie - 17-2-2015 at 19:33

That makes sense to me, so yes, that jar does look a little small, but then again, it is recommended to use distillate tails to charge it, which would help to have more alcohol in a smaller volume of course.

Why not put 100 % proof in it? Then claim you're 'doubling'? Could work but not what we're discussing here.

Yep, turn it into a proper refluxer, again: not what we're talking about. Not the thumpy people either...

[Edited on 17-2-2015 by blogfast25]

The thing is, as I understand it, there's no need for a proper reflux for making 'likker' since it's not that difficult an enrichment based on the phase equilibrium discussed earlier. So really, this seems to be a very simple solution that gets the job done. If so, then hats off :cool:

The only advantage from more trays and employing reflux is you can increase the alcohol recovered because employing a reflux ratio gives you that extra degree of freedom, but that comes at the cost of extra energy consumed to run the boiler, so really that 'ain't free neither'.

Apologies... I feel the need to start speaking 'billy.

We have "New Billy" meatins evury Tuusday.
Bring a jar!

Zombie - 17-2-2015 at 19:37

delta H:

Of course it's not free, whatever you do. No contest.

Secondary argument (already made to be fair):

If this little trick works, how come you don't read about it in engineering textbooks, journals or even half-decent internet sources (you know, the ones that might feel the need to substantiate things with experimental data)?

I posit it to you that it's for the same reason no decent person would publish anything substantiating the 'HOH' crapola: it DOESN'T WORK!

We've already covered that.
It's not efficient enough to be heralded as a "breakthru" technology. But it does it's job at allowing you to up the proof of your "hootch" in one run.

More proof = more $$$'s. That's the only reason for this.

Zombie - 17-2-2015 at 19:40

Cause snobbish academics wouldn't touch anything 'billy with a ten foot pole

Lily-livered librul academics are 'fraid they's gonna beat up by them billys with their baseball bats, for publishing their Appalachian secrets, bro. What goes on in Appalachia stays in Appalachia!

[Edited on 17-2-2015 by blogfast25]

I probably should have kept this to myself. Them Billies do mean business now.

Zombie - 17-2-2015 at 19:43

In reference to the submergence of the vapor pipe from the still: I don't know how much the typical moonshiner submerged the outlet but it would elevate the bp of the wash in the pot above that obtained using atmospheric pressure. 2.3 ft of water submergence is equivalent to 1 psi.

Zombie is likely taking one much needed nap, or he had to go to work, or both. He has been giving his all for science.

[Edited on 17-2-2015 by Magpie]

You're right on all counts Magpie.
I still haven't made dinner, and it's not looking likely.

Zombie - 17-2-2015 at 19:46

it's called a double retort:

Notice what appears to be overflow pipes to return liquid to the still :cool:

see here:

http://eatsdrinksandsleeps.com/page/5/

From that link:

Quote:

Alcohol boils as at lower temperature (78.3° C) to water 100° C. So when the pot still is heated, alcoholic vapour will be released before water is, it passes into the low wine retort, a second copper vessel which contains an alcoholic mix of low wines and water. The hot vapour passing through, boils the liquid in the retort, releasing its most volatile components. This vapour is now more concentrated in flavour and is carried through to the high wines retort, where the process is repeated. The vapour is now high strength and is condensed. By adjusting the composition of liquids in the low and high wines retorts, a distiller can create a range of different flavours.

The 'thumpers' are already charged with alcohol.

Eatsdrinksandsleeps, science 101 indeed!

Oh, yes: 'chestofbooks', Zzzzzzz....

Is that all you've got?

[Edited on 17-2-2015 by blogfast25]

We are doing exactly the same thing. 10% Alch. in both.
Low wines are the actual boiler left overs, and actually contain only 2 3% alch. far less than the boiler in that case.

[Edited on 18-2-2015 by Zombie]

Zombie - 17-2-2015 at 19:47

Quote: Originally posted by Fulmen

deltaH: The last link shows a pipe that I interpret as the return flow, making it a full stage. The first one is harder to tell, but there is something there as well.

Those returns are only drains into the boiler to empty the doublers AFTER a run is complete. They have NO bearing on this.

Zombie - 17-2-2015 at 19:50

Quote: Originally posted by Fulmen

It's the same principle really. Whether the reflux is controlled by an external condenser and divider or by partial condensation in the stage itself is irrelevant for the principle. It acts like a cooled fractionating column, not unlike what we would set up in the lab.

Sort of. You have to factor in the increasing temp of the vapor in, and the reduced boiling points of the products in the thump.

It is a combo of what you said, and what I said that makes it work

Zombie - 17-2-2015 at 19:54

To my simple mind it seems like this :-

Start Condition: Boiling pot & Thumper pot contain e.g 50w% EtOH, equal volumes

Begin heating Boiling pot.

EtOH starts leaving Boiling pot, and instantly condenses in the cooler Thumper pot liquid.

This increases the Thumper pot volume, temperature and w% of EtOH.

Eventually the temperature in the Thumper pot is sufficient for the EtOH in there to begin leaving, to be recovered in the condenser.

The main difference is that the now boiling Thumper liquid has a higher w% of EtOH than the original Boiling pot liquid.

Would anyone here have any experience in Ethanol/water distillation where the w% of the stock liquid has a marked impact on the w% of the distillate in a simple distillation ?

Would a higher concentration of ethanol:water impact in any significant way on the distillate concentration ?

Yes Mr. Aga.
I posted the graph of the BP of the liquids many pages ago.
EVERYONE keeps ignoring this ONE base fact that makes this work!!!

The BP is lower in the thumper, and always will be once Evap starts in the boiler.

The boiler temp. is ALWAYS higher in the boiler than needed in the thump. This process get stronger as the action continues.

ALWAYS!

Zombie - 17-2-2015 at 19:59

Oh.

Start with more, get more, just Less % difference.

So if the starting condition was the same in the Boiling pot and the Thumper, then the increased EtOH concentration in the Thumper pot *before* it starts boiling Will give a higher EtOH concentration in the end product, as it will be starting from a higher EtOH conc.

If so, it should end up the case that the Thumper output will have a higher w% than a straight non-Thumping distillation.

According to Thumper 101, yes. Not according to moi.

Or Fulmen.

My point is simply that that would work if you condensed the primary still pot vapours into the thumper, then externally heated thumpy. That would be 2 distillations.

Not by blowing water-rich primary vapours through it though...

[Edited on 18-2-2015 by blogfast25]

100% incorrect.
You are blowing ethanol rich vapor at a higher temp than required to vaporize more eth.

The WHOLE idea is to leave the water out of it, and compare the shifting boiling points.

The light bulb moment is near.

Zombie - 17-2-2015 at 20:01

Not quite. The vapor out of the thumper is richer in ethanol than the liquid in the thumper because of the relative volatility of ethanol to water. The thumper is acting as a vapor/liquid equilibrium stage and the increase in ethanol can be determined from the VLE diagram.

You keep forgetting that you're blowing EtOH impoverished primary still vapour into the enriched thumper liquid.

It's not like you're adding dry heat.

Carrying MUCH more heat than required to vaporize the thumper product.

Zombie - 17-2-2015 at 20:02

Erm, after all the EtOH has left the primary pot, it's all in the Thumper pot.

Thumper liquid will now be Hot.

Next the Water vapor will start entering Thumper, driving the distillation in Thumper, and changing the EtOH:Water conc as well.

Sounds like a race against time/conc.

The First distillate from the Thumper should therefore be of a Higher w% than expected from a straight distillation, with the conc steadily decreasing as the heating steam, and the evaporating EtOH reduces the Thumper EtOH conc.

Maybe the 'Great Secret' is that the first distillate out of the Thumper is the 'Good Stuff'.

Squaring the circle, the Laws of Thermodynamics are not violated at all.

Over the entire distillation, the total volume of EtOH collected will be exactly the same Thumper vs Straight distillation.

Exactly When you collect your distillate dictates your EtOH concentration when using a Thumper.

Glad we got that sorted out without all that tedious 'actually doing anything'.

[Edited on 18-2-2015 by aga]

Close. Add in the fact that the first distillate collected is of higher proof, and shut down both runs at the same point ie 20%, and the overall proof of the run IS higher. That is the only goal.
In real world practice this is approx. 25% increase.

[Edited on 18-2-2015 by Zombie]

Zombie - 17-2-2015 at 20:07

You keep forgetting that you're blowing EtOH impoverished primary still vapour into the enriched thumper liquid.

It's not like you're adding dry heat.

The thumper will always contain more alch. until there is nothing left. That is why the boiler always contains more heat energy than required to boil the thumper.

Zombie - 17-2-2015 at 20:10

Aga, I think you have the right idea. Moonshining is a batch process and the boys will shut the still down at a certain point to maximize the product to their specifications.

The overwhelming majority of your boys don't actually measure anything. 'Proof' at start and end perhaps, nothing more...

Now who is speculating...

A billy is VERY well aware of what is happening during the run
You went to school to learn how to use a slide rule, and these boys spent their lives reading bubbles in a jar.

They know more about this than you sir. Respectfully said.

Zombie - 17-2-2015 at 20:11

Aga, I think you have the right idea. Moonshining is a batch process and the boys will shut the still down at a certain point to maximize the product to their specifications.

100% YES!

Zombie - 17-2-2015 at 20:15

Someone mentioned that this could be solved with a can of beer.

I think i just did.

At the very least, the basis for a definitive experiment is now available.

Distillation, EtOH conc of distillate measured say every 10ml or so.

Distillation with Thumper, EtOH conc of distillate measured the same.

Results would show one way or the other what the Thumper does or does not do.

Get on with it !

That was me, and yes. That is all that needs to be done.

In all fairness the process must match real world application. Meaning no supper heated flasks, and uncontrolled output rates.

The goal is to reduce temps to manage water vaporization, and maintain the highest ABV output through the run.

Zombie - 17-2-2015 at 20:18

You keep forgetting that you're blowing EtOH impoverished primary still vapour into the enriched thumper liquid.

It depends on which part of the batch process you are in. In the latter part you are right and that is likely where the boys will shut down the still.

In the beginning of the distillation the vapor from the pot will be richer in ethanol than the thumper liquid.

From the very second one atom of alch vapor passes into the thumper is is always a matter of the thumper being ahead.

The run is stopped at 20% ABV from the thumper, and the thumper , and boiler should be fairly close in ABV because most everything is gone but the thumper will always be higher during the run

Zombie - 17-2-2015 at 20:23

More than that : they developed a Time Function, where they collect distillates at differing Times into the distillations.

Each Timed portion represents a different EtOH concentration.

Heads, Flow and Tails were the billyclue.

Yeehar !

[Edited on 18-2-2015 by aga]

Correct.
Fore shots are the most volatile. Acetone, and like compounds
Heads are a mix of fores, and Ethanol
Hearts are mostly pure ethanol / water
Tails are les volitle Keytones, fusel oils, ect

Fores are used around the house, de-greaser... heads are for lighting camp fires, ect... Hearts is where the money is... tails are for flavoring or modifying flavor profiles or just dumped in the dirt.

Zombie - 17-2-2015 at 20:26

In the beginning of the distillation the vapor from the pot will be richer in ethanol than the thumper liquid.

How much richer?

Wrong. For our purpose they start of the same. Once the first vapor leaves the pot, the thump is richer, and always will be.

Zombie - 17-2-2015 at 20:27

Experiment.

It seems to be the only way out of the quagmire. Let this not be another Vietnam.

Zombie - 17-2-2015 at 20:29

Thinking about it, if my drunken theory is right, the Levels of the distillation pot and the thumper are irrelevant : they need not be at the same height at all.

A quick search on moonshine thumpers found a few images of 'stills where the thumper pot is suspended in the air, above the output of the 'still pot.

Heating of the Thumper should also be undesireable, as you'd want as much of the EtOH from the 'still pot to reach it, and condense in there before Thumper starts boiling, which rules out thumper heating being desirable.

Yes sir. No extra heat is required. Heating it negates the partial condenser effect.

Zombie - 17-2-2015 at 20:39

Quote: Originally posted by Crowfjord

How do you guys plan on measuring ethanol concentration in your experiments? Depending on how small of a scale you're working with, it might be too little for a hydrometer.

I think I might join in on conducting an experiment. Maybe. I've been considering making some rum the past few weeks anyway.

If you're gonna make drinking liquor of ANY decent quality you need at least a 5 gallon boiler, and comparable thumper.

Anything smaller is just going to give yo raw liquor, and little separation of fores / heads / hearts / tails/.

Nasty stuff.

For this experiment perhaps a liter or 1000ml / 500ml rig will suffice. 750ml wash in the boiler, and 250ml in the thumper.

That should produce around 8 ml if stopped at 20% from a pot distillation, and 6ish ml from a thump distillation.

Tough to say.

Zombie - 17-2-2015 at 20:41

The actual accuracy would not be too important, as it would be a Comparison of straight distilled w% vs thumper distilled w%.

Correct. The absolute values are less important. Relative but statistically relevant numbers are far more important.

Absolute Values opens a can of worms like the use of Absolute Material Standards. Not easy. Big Science territory.

[Edited on 18-2-2015 by blogfast25]

Agreed. Comparative numbers are all that is required.

Magpie - 17-2-2015 at 20:44

The run is stopped at 20% ABV from the thumper, and the thumper , and boiler should be fairly close in ABV because most everything is gone but the thumper will always be higher during the run

If the boiler is charged with 10wt% ethanol (0.043 mole fraction ethanol) then its vapor will be 0.33 mole fraction ethanol (56wt%) according to the VLE diagram.

56wt% >> 20%ABV

Did you misread my earlier statement shown below?

"In the beginning of the distillation the vapor from the pot will be richer in ethanol than the thumper liquid."

[Edited on 18-2-2015 by Magpie]

Zombie - 17-2-2015 at 20:46

You will have a boiler / 1/2 size thumper. The boiler should be 3/4 full, and the thumper 1/2 full.

Ok, welcome back.

No gripes except with that quote. We'll be using say a V (volume) pot still and a V/2 (half that volume) thumper. If the total feedstock was say A, how should we allocate that over both? Example: 75 % in pot still, 25 % in thumper?

It'll be a small set up, probably 500 ml pot still, 250 ml thumper. Insulation on the primary vapour line, slow distillation.

Final distillate condensing will not interfere with anything, I guarantee you that.

Set up will be revealed before any distillations take place.

[Edited on 18-2-2015 by blogfast25]

That sounds fine. I would say 400ml in the boiler, and 125ml in the thumper.

One practice run to learn the rig, and I think this will do the job.

Zombie - 17-2-2015 at 20:56

Thank you.
Lobster for breakfast! That's awesome. (You are 7-8 hours ahead of me (PST), right?)

And because we're contrarians in this part of the world, I now have to go to bed, stomach full of lobster!

'Hostilities' to resume tomorrow.

Night night. Don't let the thumpers bite.

Sorry I missed ya!

See you in the am.. Hey... who am I talking to?

Never mind.

Magpie - 17-2-2015 at 20:57

I'm wondering if that because of the huge scale down factor the still outlet piping and the thumper should be well insulated?

Did you miss my previous post/question?

[Edited on 18-2-2015 by Magpie]

Chemosynthesis - 17-2-2015 at 21:04

DeltaH, thank you. Extremely useful to have graphs. It's probably a personal deficit of mine, but I hated even using the lever rule back in school, so as soon I need to start correcting for activity coefficients or the like, I am not the best person for that at all. I should definitely get that software and learn how to use it.

Zombie - 17-2-2015 at 21:09

The run is stopped at 20% ABV from the thumper, and the thumper , and boiler should be fairly close in ABV because most everything is gone but the thumper will always be higher during the run

Yes I did mis read that. You are correct. The vapor leaving the pot WILL be richer than the liquid in the thumper.

There will be a point where this equalizes, and reverses. That is approx 3/4 of the way thru the run, and nearing the end or "tails" production

Zombie - 17-2-2015 at 21:14

I'm wondering if that because of the huge scale down factor the still outlet piping and the thumper should be well insulated?

Did you miss my previous post/question?

[Edited on 18-2-2015 by Magpie]

I'm not sure about this.
The scale may play a factor...
I'm too burnt out to learn thermo dynamics tonight so maybe, if we keep this in mind for after the results come in.

I'm fairly certain the issue will be minimal and, the results if even 2 - 3 % should prove out the idea.
I expect to see around 25% increase in ABV

macckone - 17-2-2015 at 23:39

Quote: Originally posted by macckone

To answer a couple of blogfast's questions. The usual ratio is 1:3 from the original link. Assuming
that the starting and final abv are the same for the pot and thumper that would give 33% enrichment.
note that is simple mass transfer and doesn't account for heat transfer. Starting off with a cold
thumper seems to make more sense thermodynamically. Initially the stream will condense in the
thumper producing a higher abv in the thumper. Then the stream will start to pass through with the
water condensing out and alcohol being absorbed into the vapor stream. Once it reaches steady
state, the amount of water condensed must equal the amount of alcohol evaporated at a heat value
level. Note this is lower than when the thumper is absorbing heat. If the thumper is losing heat
to the environment the enrichment could be greater but never more than the mass value. Hypothetically
the thumper could be alcohol depleted at the end of the run yielding a higher gain than 33%.

My simulations showed that a cold thumper does no enriching, enrichment only starts from about 73C under my conditions where it peaks rapidly, then decreases with increasing temperature. In really, the thumper would operate somewhere above 90C I would imagine and reach that pretty quickly. I would't proof a distillate sample before the thumper gets hot and reaches pseudo steady state.

[Edited on 17-2-2015 by deltaH]

Enrichment when cold is of the liquid in the thumper not vapor, because little vapor will pass through until the thumper reaches the azeotrope BP. Then you get an enriched mix that falls rapidly to steady state. Basically we are saying the same thing.

deltaH - 17-2-2015 at 23:49

Magpie and others asked about the x-y diagram a while earlier.

The x-axis refers to the mole fraction of ethanol in the liquid phase, the y-axis refers to the mole fraction of also ethanol in the vapour phase.

*********************

The curve is the phase equilibrium for ethanol in the ethanol-water system between vapour ethanol and liquid ethanol.

The y=x diagonal line refers to the operating line for distillation under perfect conditions (infinitely large still or a multistage fractionator operating at infinite reflux/boilup ratio's and infinitely big).

Drawing the steps as I've done gives the thermodynamic minimum number of stages required to achieve a particular separation. Real life is typically twice that , as a very crude rule-of-thumb, because of inefficiencies. It's a really quick way to estimate if you want to go from say 0.05 mole fraction ethanol to say 0.5, how many stages you're going to need.

The boiler counts as a stage, thereafter each tray in a column also counts as extra stages. A thumper is at best only a partial stage, so still plus three thumpers does not equal three thermodynamic perfect steps (NB!)

For a column that operates with proper reflux, you can construct so called McCabe-Thiele diagrams for the seperation. You then get extra operating lines whose angles are determined by the reflux ratio, the boilup ratio and also a feed line (called the q-line).

See http://en.wikipedia.org/wiki/McCabe%E2%80%93Thiele_method

[Edited on 18-2-2015 by deltaH]

Zombie - 18-2-2015 at 00:12

All of that is correct Delta.

If I may make one modification...
The thump IS another stage or distillation, in as much as the boiler is considered a distillation.
The exact same process is occurring in the thumper as is in the boiler.

The only difference is the thumper now contains a higher mole fraction, and requires less energy to vaporize than the boiler.

Zombie - 18-2-2015 at 00:47

Oh yeah, it is a far cry from the efficiency of a plate by all measures.

It is the interaction of vapor / liquid that strips EtOH from the liquid (beside evaporation).
In my columns I uses a combination of sieve plates w/ 357- 1.5mm holes per plate, and .6 stainless mesh "structured packing".
Combined I run the equivalent of 18 stages or plates in a 7 foot tall combined concentric column / boiler. It produces approx 5.5LPH at azeotrope. Different beast.

It is all about vapor / liquid interaction. Thumpers do this in the most simplistic fashion, and I'm sure they ( operators) never quite understood why or more complex or efficient stills would have come out of the mountains / woods.

deltaH - 18-2-2015 at 01:07

Oops I accidentally erased my post when I meant to erase the image in an edit, but basically the post above zom's should read something like:

Yes, it is a stage, I just want it understood that it's a much smaller step of the phase diagram than an ideal stage (and the still's step for that matter). So two thumpers and a still does not make three ideal steps etc.

I'm just emphasising this for those who do not have distillation knowledge and working with such diagrams. Not most of those participating in the thread though.

deltaH - 18-2-2015 at 01:13

Oh yeah, it is a far cry from the efficiency of a plate by all measures.

It is the interaction of vapor / liquid that strips EtOH from the liquid (beside evaporation).
In my columns I uses a combination of sieve plates w/ 357- 1.5mm holes per plate, and .6 stainless mesh "structured packing".
Combined I run the equivalent of 18 stages or plates in a 7 foot tall combined concentric column / boiler. It produces approx 5.5LPH at azeotrope. Different beast.

It is all about vapor / liquid interaction. Thumpers do this in the most simplistic fashion, and I'm sure they ( operators) never quite understood why or more complex or efficient stills would have come out of the mountains / woods.

I get what you're saying fully.

The thumper seems an elegantly simple solution to getting the job done and if so, then hat's off (as I've said before).

Whoever carries out this experiment, please afix a cutout of the following image on the thumper jar as the official mascot of this thread

"Thumper" from "Bambie"

[Edited on 18-2-2015 by deltaH]

Zombie - 18-2-2015 at 02:43

I've been wondering who was going to post that Thumper first.

14 pages, and we get a real working thumper. Whew...

blogfast25 - 18-2-2015 at 02:44

You will have a boiler / 1/2 size thumper. The boiler should be 3/4 full, and the thumper 1/2 full.

That sounds fine. I would say 400ml in the boiler, and 125ml in the thumper.

One practice run to learn the rig, and I think this will do the job.

Fair enough. Practice run seems fair.

blogfast25 - 18-2-2015 at 02:57

Real life is typically twice that , as a very crude rule-of-thumb, because of inefficiencies. It's a really quick way to estimate if you want to go from say 0.05 mole fraction ethanol to say 0.5, how many stages you're going to need.

A minor gripe. That statement is fairly meaningless.

Fractionated columns in industry are designed using fairly accurate design criteria to make them fit-for-purpose.

Actual column performance is then determined mainly as the Number of Theoretical Plates (as well as other parameters) (McCabe Thiele, in essence).

blogfast25 - 18-2-2015 at 03:06

It is the interaction of vapor / liquid that strips EtOH from the liquid (beside evaporation).

Again, relatively minor gripe.

In modern fractionating theory, the process is considered just another counter-current separation method like liquid-liquid separations for instance.

Vapour gets sent up by boiling and liquid gets sent down by the refluxer. Mass transfer occurs between the two phases with the more volatile component being enriched in the vapour phase according to the x,y operating diagram.

You want to call that an 'interaction' but that's unnecessarily vague.

deltaH - 18-2-2015 at 04:23

When I say 'real life', I mean real vs ideal, nothing about professional industrial column design. This amateur friendly rule of thumb for distillation does in fact have a theoretical basis... the Gilliland correlation used by professional chemical engineers. As you probably know, but for the benefit of others, Gilland undertook a study of actual commercial distillation over a wide range of types and purposes and plotted them on scales so that an emperical correlation could be drawn between the number of real trays and the real reflux ratios in actual operation versus the theoretical minimum stages and minimum reflux. What he found was this:

Now, notice that there is a much larger number of dots near the elbow region. If you take my abovementioned rule of thumb of N = 2N_min, substitute that into his y axis formula and make the assumption that N >> 1, you arrive at an y-axis value of 0.5, which is the upper-bound of that main grouping. That means this is a safe value to pick for most cases to get the job done within reason.

Professional column design, like you rightly say, are done to strict guidelines, but this rule of thumb is very amateur friendly if you're not trained in chemical engineering.

j_sum1 - 18-2-2015 at 04:43

Delta, you are not living up to your tagline very well.

Quote:

Dangerous source of unreferenced speculation

deltaH - 18-2-2015 at 05:28

blogfast25 - 18-2-2015 at 05:33

Delta:

That is a very interesting study and new to me. Time allowing, I will look into that with more zeal.

I still prefer (old habits die hard!) the cumbersome calculations needed to design a suitable rectifying system from scratch because it's such a good example of where rationalism, empiricism and historicism blend well and produce real world results.

deltaH - 18-2-2015 at 05:53

The Gilliland correlation is old, it's part of what's called the FUG[K] shortcut column design method (stands for Fenske, Underwood, Gilliland, Kirkbride). First you calculate the minimum number of theoretical plates using the Fenske equation, then you calculate Rmin from the Underwood equation, then use those values in the Gilland correlation with your rule of thumb of choice and finally the Kirkbride tells you the best tray to feed on. Easy peasy... kinda

It's covered over the net and in many chem. eng. separation texts.

***************************************
The free software Chemsep LITE, for those who are familiar with distillation column, is a very powerful and easy software to simulate equilibrium columns, draw McCabe-Thiele diagrams, phase diagrams and much, much more. It comes with quite an extensive library of components and thermodynamic models and data. For a modest fee, the author will sell you the full version that can do non-equilibrium column design with a very wide range of industrial packings and trays. It's impressive to use. Chemsep LITE also automatically comes when you download COCO (which it integrates with), the free process simulator for multiple unit operations.

Anyhow, I'm digressing from thumpers...

[Edited on 18-2-2015 by deltaH]

blogfast25 - 18-2-2015 at 06:11

The Gilliland correlation is old, [...]

I'm only 18 so I wouldn't know about that... Nope, 81. Dammit, I'm so old I can't remember when I was born!

[Edited on 18-2-2015 by blogfast25]

deltaH - 18-2-2015 at 06:17

The Gilliland correlation is old, [...]

I'm only 18 so I wouldn't know about that... Nope, 81. Dammit, I'm so old I can't remember when I was born!

[Edited on 18-2-2015 by blogfast25]

You're as young as the woman you feel

[Edited on 18-2-2015 by deltaH]

blogfast25 - 18-2-2015 at 06:53

Question for Zombie:

What method do you use for alcohol determination?

Magpie - 18-2-2015 at 09:32

One method that may be of value would be "determination of boiling point." Toggle the diagram below. However, I would not try to use this particular diagram as the axes are not scaled. Surely there are scaled ones available on the internet.

blogfast25 - 18-2-2015 at 09:50

Magpie:

Accurate BP determinations (e.g. capillary method) aren't easy and are time consuming. We may have to analyse up to 50 samples.

[Edited on 18-2-2015 by blogfast25]

deltaH - 18-2-2015 at 10:11

Ethanol and water have strongly differing dielectric constants, so measuring the capacitance of the solution with a multimeter using a small vial and two fixed electrodes should work well. You would need to calibrate of course from a set of alcohol solutions of known strength.

NB: the electrodes would need to be physically well fixed in the vial to not move at all so as to maintain consistency and insulate the electrodes with a thin layer of... whatever

Physics is NOT my strong point, so not sure if this can work.

If too small a capacitance is a problem, one could use an open multiplate variable capacitor and immerse it (not sure if immersion would be a problem). The only danger there is that you would need to make sure that no air bubbles trap between the plates as this would introduce an error. Tap it?

[Edited on 18-2-2015 by deltaH]

aga - 18-2-2015 at 10:17

Whatever method of determining the EtOH concentration won't matter muchly, so long as it's granularity is reasonably fine (e.g. 0.5%), is done with the same equipment, and by the same operator.

It's a Comparison, so the absolute accuracy will not be vital.

Your suggested refractometry thing would be fine for this purpose.

Some calibration would make your data more generally useful of course.

blogfast25 - 18-2-2015 at 10:25

Your suggested refractometry thing would be fine for this purpose.

Some calibration would make your data more generally useful of course.

In all likelihood, yes. A rough idea of both accuracy and repeatability would be useful. A simple statistical analysis on the obtained data would give an idea of confidence levels.

deltaH - 18-2-2015 at 10:28

Whatever method of determining the EtOH concentration won't matter muchly, so long as it's granularity is reasonably fine (e.g. 0.5%), is done with the same equipment, and by the same operator.

It's a Comparison, so the absolute accuracy will not be vital.

Your suggested refractometry thing would be fine for this purpose.

Some calibration would make your data more generally useful of course.

The refractive indices of water and ethanol vary by only 0.027. So increments of 0.5% would mean increments in refraction index measurements down to 0.000135

Is that typical of these instruments (never worked with one, so wouldn't know)?

[Edited on 18-2-2015 by deltaH]

blogfast25 - 18-2-2015 at 10:46

The refractive indices of water and ethanol vary by only 0.027. So increments of 0.5% would mean increments in refraction index measurements down to 0.000135

Is that typical of these instruments (never worked with one, so wouldn't know)?

Yes. There are refractometers that are specifically designed for EtOH/water, in that range of index.

deltaH - 18-2-2015 at 10:56

Nice! Cost?

blogfast25 - 18-2-2015 at 11:02

Nice! Cost?

About £25.

I think 1.0 % will be about the accuracy to be expected but if the overall variation S is good then that will be good enough.

Better than 'billy bubbles'!

deltaH - 18-2-2015 at 11:40

Yeah, PERFECT!

chemrox - 18-2-2015 at 12:11

The thumper serves as a partial takeoff head to drain off water and some of the "fusel oil". It's not as efficient as some of the fractionators built into modern so-called moonshine stills.

aga - 18-2-2015 at 12:30

There's a Digital refractometer :-

http://www.ebay.co.uk/itm/Refractometro-digital-de-Alcohol-p...

Zombie - 18-2-2015 at 13:56

It is the interaction of vapor / liquid that strips EtOH from the liquid (beside evaporation).

Mass Transfer. Correct. Even when I know the lingo I tend to oversimplify.

Zombie - 18-2-2015 at 14:11

Question for Zombie:

What method do you use for alcohol determination?

Breathalyzer...

No, I have a Chase Inst. hydrometer calibrated at 60*f, and use a Kessler -20*C / +150* C thermometer.

My runs begin @ 80% abv, and I stop @ 20% abv.
Average or final proof @ 100.

[Edited on 18-2-2015 by Zombie]

Zombie - 18-2-2015 at 14:14

One method that may be of value would be "determination of boiling point." Toggle the diagram below. However, I would not try to use this particular diagram as the axes are not scaled. Surely there are scaled ones available on the internet.

I posted one up in the first few pages here.

Vapor-Liquid_Equilibrium_Mixture_of_Ethanol_and_Water.png - 15kB

Zombie - 18-2-2015 at 14:22

Quote: Originally posted by chemrox

The thumper serves as a partial takeoff head to drain off water and some of the "fusel oil". It's not as efficient as some of the fractionators built into modern so-called moonshine stills.

Pretty much on the money there.
A large part of what they do is compress the fractions allowing the lightest to come of cleaner. Same with the desired middle fraction (EtOH), and the less volatile keytones, fuesils last.

[Edited on 18-2-2015 by Zombie]

blogfast25 - 18-2-2015 at 16:58

I posted one up in the first few pages here.

Sure but what method do you use?

Zombie - 18-2-2015 at 17:39

I don't understand the question sir.

What method did I use for what?

Magpie - 18-2-2015 at 18:28

I'm guessing he uses his hydrometers, right?

Zombie - 18-2-2015 at 18:54

I'm guessing he uses his hydrometers, right?

For testing ABV, Breathalyzers...

Yes, a Hydrometer. Calibrated at 60*f, and always tested at the correct temp rather than doing Temp. correction formulas.

blogfast25 - 18-2-2015 at 19:13

I'm guessing he uses his hydrometers, right?

For testing ABV, Breathalyzers...

Yes, a Hydrometer. Calibrated at 60*f, and always tested at the correct temp rather than doing Temp. correction formulas.

Breathalizers for alcohol by volume? Explain, please.

Zombie - 18-2-2015 at 19:16

It was a joke.

I posted a few posts back the equipment. You must have missed it.

" I have a Chase Inst. hydrometer calibrated at 60*f, and use a Kessler -20*C / +150* C thermometer.

My runs begin @ 80% abv, and I stop @ 20% abv.
Average or final proof @ 100."

blogfast25 - 18-2-2015 at 19:23

Fahrenheit should be banned.

Proof @ 100 in the US means 50 % by ABV, correct?

Zombie - 18-2-2015 at 19:32

Fahrenheit should be banned.

Proof @ 100 in the US means 50 % by ABV, correct?

Correct.

I'll work on the Fahrenheit usage.

I expert your results will yield similar ABV readings.
The single pot distillation usually begins @ 60% ABV, and stopping at 20% ABV yields 40 ABV average.
But the 60% ABV initial reading drops very quickly in a single pot so the end result is usually closer to 30% ABV.

The thump tends to stabilize the run, and compress the fractions, much the same a a plate in a column will.

[Edited on 19-2-2015 by Zombie]

blogfast25 - 18-2-2015 at 19:36

Ta.

Zombie - 18-2-2015 at 19:47

Buonanotte...

blogfast25 - 19-2-2015 at 03:10

Iraliano, Signore? Meraviglioso!

Luke - 19-2-2015 at 04:21

Zombie- How accurate is a alcometer (hydrometer) to measure abv if temp fluctuates 5C? Its usually around 20-30C here and i just measure at ambient.

Also, how accurate are the alchol refractometers? They are pretty cheap here as well.

Zombie - 19-2-2015 at 05:57

Iraliano, Signore? Meraviglioso!

Sono cresciuto in Yonkers NY , e il mio quartiere era 1/2 italiano , e 1/2 irlandese .
Led ad una infanzia dura ...

Zombie - 19-2-2015 at 06:06

Quote: Originally posted by Luke

Zombie- How accurate is a alcometer (hydrometer) to measure abv if temp fluctuates 5C? Its usually around 20-30C here and i just measure at ambient.

Also, how accurate are the alchol refractometers? They are pretty cheap here as well.

Every hydrometer (worth the cost) will come with a Temp. conversion chart. I used a cheep meter for a short time, and found it was 3 points off at 70*f (21* C).

You can also order them set / calibrated to specific ambient temps. but it is best to chill the product / sample to whatever the calibration point of the meter is.

I have never used a refractometer for Alch levels but I do use one for sugar content. You have to know the mash conversion ratio to judge the yield.

blogfast25 - 19-2-2015 at 07:32

Quote: Originally posted by Luke

Also, how accurate are the alchol refractometers? They are pretty cheap here as well.

The one we have in mind is advertised as 1 ABV % error. But we'll find out exactly before we use it, experimentally, before we measure the thumper/no thumper comparison.

Whether or not 1 % is good enough resolution will depend largely on two factors:

1. repeatability of each measurement
2. spread (or range) of ABV readings over the runs, known also in Statistical Mathematics as 'variation' or 'total variation'

This will be handled very carefully, trust me on that.

[Edited on 19-2-2015 by blogfast25]

Zyklon-A - 19-2-2015 at 09:42

I haven't read this whole thread, but I'm trying to understand what the exact problem is.
Are you (Blogfast) saying that a thumper can't increase the alcohol concentration, or that it can't be energy efficient? Or both?
Because the latter is obvious. If it distills it twice, it needs the energy added twice. But as for increasing the conc., why can't that work? If 80% ETOH and 20% water enters the thumper, which we'll say is saturated, the water will condense first right? So if the temperature of the thumper is around ETOH's boiling point, most ETOH won't condense, but the water will.
Also, since most ETOH doesn't condense you won't have to add twice the energy, just a little more. As the water condenses it adds energy to the ETOH (well the solution as a whole), if energy is added fast enough, then the gaseous water and liquid ETOH in solution will change places no?
H₂O (g) + ETOH (aq) --> H₂O (l) + ETOH (g) + 1,405 J/gram
Sorry if I'm hijacking your thread with already stated/debunked pseudoscience, just my two cents.
From here

Quote:

Though "thumper kegs" are sound in principle and do raise proof, they are very energy-inefficient. Still designers discovered that the enrichment process could be more effectively accomplished by stacking one still atop another. This technique is called the pipe column.

Fahrenheit should be banned.

God bless you, I hope so too.

[Edited on 19-2-2015 by Zyklon-A]

blogfast25 - 19-2-2015 at 10:32

Quote: Originally posted by Zyklon-A

I haven't read this whole thread, but I'm trying to understand what the exact problem is.
Are you (Blogfast) saying that a thumper can't increase the alcohol concentration, or that it can't be energy efficient? Or both?

Zyklon, I've explained my position probably about 20 times now and have heard yours equally often. I'm not about to repeat myself one more time.

Don't take that the wrong way. :cool:

Zombie - 19-2-2015 at 11:01

Quote: Originally posted by Luke

Also, how accurate are the alchol refractometers? They are pretty cheap here as well.

100% faith in you fellas.

aga - 19-2-2015 at 11:56

Keep the faith going !

Blogfast25 has roped me in to do the dirty work, as he's currently 100% committed to skiiving.

Here's the photos of what Bloggers and i think will provide a fair approximation of a Thumper, using standard glassware.

The missing bits are the 500ml RBF on the Left, which will replace the 250ml one, a 24 to 19 reducer for the stillhead on the right, and a 19 thermometer adapter where the plug is on the left hand neck of the 3-neck RBF.

The 'Thumper' comprises a 3-neck 250ml RBF, with the centre neck taking the vac adapter coming from the boiling pot (the vac takeoff will be stoppered).

The glass tube inside the vac adpater has been lengthened by adding some tubing to hold on another length of glass tube, cut to length so it almost touches the bottom of of the RBF.

The missing bits & refractometer are all on order, so we are currently waiting for the postman.

Any thoughts or suggestions ?

Crowfjord - 19-2-2015 at 12:02

Hey, alright! That's almost exactly of what I was thinking of doing, too! I think I'm going to use a 2000 mL RBF for the boiler and a 1000 mL one for the thumper, though. Since I only have one still head, I figured I would use the vacuum adapter of the take-off as the outlet to the condenser.

aga - 19-2-2015 at 12:20

One stillhead ?

Perhaps you're more careful with your glass than i am ...

Get a spare rig :
http://www.ebay.co.uk/itm/500ml-Glass-Distilling-kit-Chemist...

£41 all-in. Quality is actually rather good.

Zombie - 19-2-2015 at 12:28

I believe that will work perfectly.

Key to the thumper is having the vapor inlet as close to the bottom as can be done. In fact touching the bottom is the way a proper thump is run. It creates smaller bubbles, and allows for more vapor / liquid interaction.

An experienced distiller has no need for a thermometer because we judge Temp. by product out put,
In this case it may help you to install a thermometer in the boiler to monitor temp. You will see the temp rise as the EtOH is evacuated.
Rule of thumb is the temp will hit approx 208 at or near the same time as the product out is at or near 20% ABV. This is just a guide, and not set in stone.

Thank you for jumping in on this Mr. Aga.
Mr. Crowfjord, I appreciate your interest as well. Two independent attempts at this can only help solidify the findings.

If the refractometers don't work out... Shake a bottle!

Thank you fellas!

aga - 19-2-2015 at 12:33

208 is a lot of centigrade, so i assume you mean Farenheit ( or 97C).

That implies it's the liquid temperature rather than the Vapor temperature, which is what i watch in normal distillations.

For the experiment, there will hopefully be 3 thermometers: 1 for each stillhead for the Vapor temperatures, and one in the Thumper Liquid.

[Edited on 19-2-2015 by aga]

aga - 19-2-2015 at 12:35

Key to the thumper is having the vapor inlet as close to the bottom as can be done. In fact touching the bottom is the way a proper thump is run. It creates smaller bubbles, and allows for more vapor / liquid interaction.

If i'd have known that, i'd have ordered a frit as well !

Loptr - 19-2-2015 at 12:41