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Just mentioning the obvious here but distillate temp could also be affected by the power changes so we have to be sure and temp correct the readings.

But you guys already knew that. Just thought I'd put it out there for those of us following along.

Right. That is why I mentioned the ABAB format. I'll be more specific in the future.

Cool still.

In all these years no one has tested/documented this theory? Seems like one of the first things a caveman would have tried to figure out.

Ok, so here is what I'm gonna do either Thurs or Friday night: The 15 gallons of wash I have will be divided into three 5gallon batches. The first five will be ran as hard as I can run it collecting by the pint and checking abv of each pint.the second 5gallons will be ran like a spirit run,slowly brought to temp and at fast drip to broken stream collected by the pint also,with a abv of each pint. The cleared and racked wash will be stirred before dividing it to insure that the alcohol is equally well mixed in each 5 gallon. The wash is by my calculations 9.26% alc,and is ujssm with corn and oats gen4. Once my part in this experiment is complete all collected will be re ran with the remaining 5 gallon of wash.
Jb

jb-texshine wrote:Ok, so here is what I'm gonna do(...)Jb

Cool. Out of curiosity, before you run your experiment, what's your expectation? Where do you stand, or which way are you leaning on the question of the effect of power on vapor composition (all other variables controlled)?

My prediction is that any differences will fall well within measurement error, corroborating the idea that power affects time only. I was about to caution you that a cold stilling environment might cause passive reflux which would be significant and measurable in a low power regime blah blah blah, but I actually don't even believe that. I can see through my top sight glass that I had some dripping from my riser back into the boiler, and my experiment still showed no effect. Looking forward to your results. Thanks for "replicating".

just interested in the results and was reading through all the posts and saw I could help out...personal experience has shown me that the same wash in a stripping run puts out less abv than the same ran as a single run spirit run...
Jb

jb-texshine wrote:Once my part in this experiment is complete all collected will be re ran with the remaining 5 gallon of wash.Jb

Sounds like the potential for a lot of flavor.

FreeMountainHermit wrote:

jb-texshine wrote:Once my part in this experiment is complete all collected will be re ran with the remaining 5 gallon of wash.Jb

Sounds like the potential for a lot of flavor.

God I hope so!!! Vodka ain't my thing.

Badmotivator wrote: I was about to caution you that a cold stilling environment might cause passive reflux which would be significant and measurable in a low power regime blah blah blah, but I actually don't even believe that. I can see through my top sight glass that I had some dripping from my riser back into the boiler, and my experiment still showed no effect. .

Been reading this thread with interest ......its something I've struggled to grasp and the reflux at low powers is something that always nags at me as a plausible reason .
So would it be reasonable to suggest that jb-texshine and others that may try this could wrap a blanket or similar around their Risers and boiler tops to insulate and reduce or negate any reflux to help with the test to see if power alone will cause any changes in ABV ( samples all cooled to the same temp obviously before testing)

My tuppence is only observational as my record keeping sux , but as my pot stills have got bigger and the ability to crank more gas up them has got bigger , my average ABV for a strip has got lower over the years .....which seems to support the notion that a higher power will result in a lower ABV ......and if you can smear water and ethanol then that's what it is

Yummyrum wrote: So would it be reasonable to suggest that jb-texshine and others that may try this could wrap a blanket or similar around their Risers and boiler tops to insulate and reduce or negate any reflux to help with the test to see if power alone will cause any changes in ABV ( samples all cooled to the same temp obviously before testing)

My tuppence is only observational as my record keeping sux , but as my pot stills have got bigger and the ability to crank more gas up them has got bigger , my average ABV for a strip has got lower over the years .....which seems to support the notion that a higher power will result in a lower ABV ......and if you can smear water and ethanol then that's what it is

JB can do it if he likes, of course, if that would help him feel confident that he was running an "ideal" pot still. But like I said, I had some passive reflux and I still got a negative result.

By the way, I think a negative result is more persuasive than a positive one would be. With a positive result, there are a variety of things which could be causing a difference between low power and high power: reflux, condenser issues, mixing in the parrot, ambient temperature, misreading hydrometer, whatever. But with a negative result, if despite all your efforts you can't get the ABV to rise by lowering the power from highest setting to lowest, it's just damned near impossible to maintain the belief that power affects ABV.

Badmotivator wrote:I can see through my top sight glass that I had some dripping from my riser back into the boiler, and my experiment still showed no effect.

Actually, I think that enrichment by passive reflux would have to depend on reflux combining with vapor and reboiling in mid air, or on the sidewalls above the charge. Once it drips back into the wash it has lost the advantage of the first boil and it's back to square one.

I'm hoping to get my rat killing done so I can run a strip on Saturday. Disproving the hypothesis would relieve the discord in my mind that I have been unable to resolve for years. And, unlike American politicians, I am perfectly willing to change my position in the face of overwhelming evidence, but in that case, I am afraid we'll have to revisit the whole idea of running low and slow to reduce smearing.

Off to kill rats.

most pot stills have sides. Most of the sides go waaaaaaaaaay up and are exposed to the atmosphere and not insulated.

the sides of the still above the liquid actually reflux back down. If you run very low heat, the steam will actually be slightly lower than the boiling wash, and this causes reflux, which causes separation a bit.

Turn up the heat, and the total BTU's of the system guarantees the entire liquid/vapor system is ALL the same temperature. A master distiller who is patient and practiced uses this to make good tasting stuff. In particular, you can turn the heat waaaaay down and pull the heads off separate. And you can minimize some of the tails from "coming up too soon" in the rest of the product.

that is all theory. I'm not a master distiller.

Might have to setup the borosilicate column unpacked in pot still mode. It's been put away for a while since the novelty wore off.

Heat loss (in watts) from an uninsulated copper pipe.

from http://www.engineeringtoolbox.com/coppe ... -d_19.html" onclick="window.open(this.href);return false;" rel="nofollow

Not negligible IMHO.

If a pipe was long enough that all the energy put in was lost then you would have 100% reflux. i.e. all of the distillate would be converted back to liquid and no vapour would escape at the top.

So:

(heat loss/heat added) * 100 = % reflux

Is that right? I've never studied the maths of still design but now I might have to.

Working on that (which may be wrong). Let's say we have a 2" riser 30 cm tall (Only a Brit can mix measurement systems like that). Say 70C temperature difference from ambient. Guesstrapolestimating from the above diagram we would have maybe 50W lost in the riser. If the input power were 2kW then we would have 2.5% reflux. If it was reduced to 1kW we would have 5% reflux.

Is this enough to make the observed difference in "smearing"? I've no idea, but at least we have some numbers now.

Please discuss.

OK. I invented my own definition of reflux ratio above. It seems that the standard definition is the ratio of the liquid returned to the column divided by the liquid removed as product.

So the 2 reflux ratios I mentioned should be 0.053 and 0.026.

Badmotivator wrote:I have been playing around with some models I found on demonstrations.wolfram.com in the chemical engineering section related to batch distillation. I had to install a "player" to play with the parameters. The ones which interested me were the ternary mixtures. (Ternary Batch Rectification, and Multicomponent Simple Batch Distillation especially.) These models have sliders for relative volatilities of the components, number of stages, and reflux ratio, but they do not have any variable power term in the model. I view this as circumstantial support for my hunch that power does not matter, except as it affects reflux ratio. (This is not likely a large effect in a simple pot still.)

Also, I found a guy with a doctorate in Chemical Engineering, who many years ago designed and ran refineries (petroleum distillation), and I sketched out the problem I'm having. He has promised to review the problem and respond this week.

Visually, the problem is this: using adjustments to power ONLY, can you shift the distillation from something that looks like this:

low reflux resized.jpg

to something that looks more like this:

high reflux resized.jpg

How do these diagrams look with my tiny reflux ratios?

I'm guessing pretty much like the first one indicating that reflux isn't much of a factor (otherwise you wouldn't have turned it up so high) Those who intuited that it is so are most likely right but I'm much happier now I have some numbers.

So what the hell causes this smearing/non smearing phenomenon? It must be entrainment I guess.

Without packing, doesn't all reflux return to the boiler, negating the effect? If so, there would be no impact on the distillate.

masonsjax wrote:Without packing, doesn't all reflux return to the boiler, negating the effect? If so, there would be no impact on the distillate.

Almost totally, yes. Bare pipe does have some HETP, but it's huge, meaning that you'd need a gigantic riser to have the same reboiling effect as one plate.

IanD wrote:
How do these diagrams look with my tiny reflux ratios?

I'm guessing pretty much like the first one indicating that reflux isn't much of a factor (otherwise you wouldn't have turned it up so high) Those who intuited that it is so are most likely right but I'm much happier now I have some numbers.

So what the hell causes this smearing/non smearing phenomenon? It must be entrainment I guess.

Awesome work! Between your extremely-low reflux numbers and the extremely high HETP of pot still risers, I think it's safe to say that passive reflux should have no useful effect. This is consistent with my observation. I'm glad you looked into the reflux numbers. Thanks.

I have also read countless times that a power supply that "cycles" causes smearing, and I now see that as another incarnation of the Power Myth. Power does not influence vapor composition, and neither does turning off the power and turning it back on. Thoughts?

IanD wrote:So what the hell causes this smearing/non smearing phenomenon? It must be entrainment I guess.

That's what I think. And it's the cause, why the old distillers put so much attention on the geometry of their stills. Entrainment depends on vapour speed. Vapour speed depends on diameter and power input.
And perhaps another factor for entrainment is the intensity of boiling (what of course depends on power too). A hard boiling causes a more chaotic composition of the vapour in the first centimeters above the mash, the bubbles sprinkle also elements with high boiling points and even solids into the vapour. When they are in the vapour they are easy to entrain.
Perhaps negation of entrainment in distillation is similar as to say, sandstorms in the sahara are not possible, because sand is heavier then air.
I think, much of the taste we get we would not without entrainment. Probably it has more effect than the most of us think.
More power - more entrainment - more taste (good and bad).

Thank you all for this promising thread.

Cool. If the idea that low power helps separation of the fractions is true, then entrainment is the only plausible mechanism, and it is easily eliminated by stuffing a modest amount of scrubby in the vapor path.

But just visualize for a moment a pot still on full power. Imagine your output stream. Now try to picture how much mist could a) be created by a vigorous boil and b) actually get picked up by the vapor and brought out the pipe, and c) not hit a wall before going over the top. Compare those two flows, output stream and mist stream. Does anyone expect the escaping entrained droplets, (which are just wash, not concentrated late fractions) to contribute any more than a thousandth of the output?

5 gallon ran as a spirit run in progress will update upon completion.

I don't think, we can stop entrainment with scrubbies. Because we can make "dirty" tastefull drinks with a packed reflux column too. Perhaps because you can't protect against a sandstorm with a tennis racket. Probably entrainment cannot push as many solid particles in visible size up the column as a potstill without a riser, but oils and tiny size solids perhaps are easy.

jb-texshine wrote:5 gallon ran as a spirit run in progress will update upon completion.

We all are thinking of you.

Your intuition is that vapor is blowing madly out the pipe at full speed, which is correct. 2" column, 4 kW, 58 inch vapor speed. But at the surface of the wash in my keg the vapor speed is 1 inch. To call that environment a sandstorm seems a little much.

Done.jars cooling to room temp of 66deg f. A half pint of foreshots and 6.5 pint jars collected at a rate of 10 min a jar.soon as they hit room temp I'll do a jar by jar.

Just an observation - may or may not be relevant to the discussion. For the past 3 days, I have been doing single run apple brandy distillations with a thumper attached. I run a 5 gallon pot still boiler with a 4 gallon thumper. The boiler and thumper were charged with the same wash - 4 to 4.5 gallons in the boiler and 1 to 1.5 gallons in the thumper. When I use the thumper I move the pot still riser from the boiler to the thumper output. The riser is 1" copper 28" long from the base of the lid to the curve of the first 90.

My concern with having an over-charged thumper was that it may start producing output without the charge being evenly heated - that is, fractions wouldn't be evenly released causing more smearing than usual. I think we're all familiar with the idea of feeling the riser and detecting the gradual warming of the riser from bottom to top. It began to dawn on me that the longer the riser, the longer it would reflux the vapor back to the thumper and allow more time for it to come up to heat. Uneven heat up has also been discussed when doing on-the-grain distillation with steam injection. Someone suggested pointing the liebig condenser toward the ceiling and refluxing long enough for the steam boiler to come up to heat.

That got me to wondering about giving the riser a little assistance by wrapping something like a 1/4" copper coil around the outside of the top of the riser to force some reflux back to the boiler/thumper. This coil would only be run temporarily to assure full heat up of the mixture before releasing it to the output PC. This is nothing new. I've read about it on the forums before, but really didn't understand its potential at the time. This seem like it would be worthwhile - especially in the case of an over-charged thumper.

5 gallon low and slow.
half pint foreshots trashed
Pint 1. 64%
Pint2. 56%
Pint 3. 54%
Pint 4. 51%
Pint 5. 48%
Pint 6. 44% cloudy
1/2 pint. 36%
Ran the rest down to15% in to feints jar.

(Sorry, I double-posted. Ignore this post)

der wo wrote:I don't think, we can stop entrainment with scrubbies.

Perhaps not, but if you believe entrainment is a significant contributor to smearing (I don't) you might be interested in this page about demisters: http://encyclopedia.che.engin.umich.edu ... ators.html" onclick="window.open(this.href);return false;" rel="nofollow
It can be as simple as this: