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# Pressurized Boiler

edited December 2021 in General

We spoke about the 3 chamber still developing pressure to push through the water column. That's the reason the the temperature of the boiler goes above the normal boiling point of 212f. What if we skip that part and intentionally create a boiler that develops pressure (1-2 bar) and uses that spirit steam to then directly heat a secondary kettle or thumper? I could see using something like a prv valve type assembly though it would need to be larger.

Thoughts?

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• edited December 2021

There just isn’t any way a 3 chamber is even remotely 1 bar. Realistically, maybe 1 psi/.1 bar.

You would need more than 2 foot of liquid column to get 1 psi.

The pressure impact can’t be pushing temps all that much.

• edited December 2021

Convert pound/square inch to foot of water [4 °C] @ Conversion of Measurement Units

8' = ~3.5 psi (2 upper chambers at 4' each section)

I would want to be able to adjust it but 1 bar would be a good upper limit. And if you're going to do something wild it should be wild.

• edited December 2021

Yes, but something still smells fishy in Denmark, err, Denver.

You mentioned altitude in the other thread, we're talking about a range of boiler pressures that's well within the realm of atmospheric pressure changes on earth. The swing between a beautiful high pressure day at sea level, and a stormy summer day in the mountains, is easily wide enough to accommodate this kind of range. If the impact of pressure alone was so significant, I would have imagined that this would be well known by now, are sea level distillers far more regarded than mountain distillers?

If there is a meaningful phenomenon here, it's not due to temperatures (that's just a symptom), it's due to shifting azeotropes. It's well known that under vacuum, the ethanol/water azeotrope weakens significantly, and is "broken", by about 1.7psi, so I would assume under pressure, it would strengthen. However, there isn't a whole lot of readily available data on that (people care about breaking azeotropes generally, not the other way around). The interesting thing is there are LOTS of azeotropes in beverage distillation, it's not just (the very well known) ethanol/water azeotrope. There are even 3-way azeotropes that include esters (ethyl acetate/ethanol/water), and plenty of heavy alcohol (fusel) azeotropes). What's really interesting, is that it's not a universal either, some azeotropes can strengthen under reduced pressure, and the opposite is true as well. Again, there is so little information on this phenomenon in beverage distillation, you want to go for a PhD in this topic, it's green field.

Easy way to do this, just add a deep thumper. A variable pressure control still would require a sealed collection system, just as a vacuum still does. It would be relatively easy to control the pressure in the still using a pressure regulator (back pressure regulator) after the condenser (exactly like you have in a vacuum still, just the opposite impact). The back pressure regulator is far more accurate and controllable than a PRV, however the principal is the same, vent gas to hold a specific pressure. Ideally, you run the back pressure regulator as well as the PRV for safety. You'll need to make sure you don't have a leaky system, since you'll hit a point in the distillation where repressurization becomes more difficult, and you then need to add pressure externally (using a compressor or similar).

You could maybe do something with a back pressure regulator before the condenser, however this is a real challenge as you are dealing with regulating hot alcohol vapor at a very high flow rate, and you need to be able to control an incredibly wide range of flow rates.

Seems easiest to accomplish this with a deep thumper.

• edited December 2021

I think we find one important hint in this 1956 grad school thesis. It may not be about pressure or temperature, but about lower ethanol composition in the distillate:

Higher Alcohols in the Alcoholic Distillation From Fermented Cane Molasses (PDF)

The removal during distillation of fusel oil, which essentially consists of alcohols higher in molecular weight than ethyl, is of great importance since, due to its nature, it is largely responsible for the defects found in industrial alcohols and alcoholic beverages especially those of the lighter types as Puerto Rican and Cuban type rums.

Its separation in the distillation process introduces technical complexities. These alcohols are completely soluble in ethyl alcohol and being less volatile, can be separated by fractional distillation. They are, however, essentially immiscible in water and by the enhanced vapor pressure phenomena, or steam distillation effect, their relative volatilities, referred to ethyl alcohol, are greatly increased beyond 1.0 when low alcohol concentrations are reached in the distillation process. This results in the fusel oil accumulating in fractions of definite alcohol concentration.

• edited December 2021

And check out this one - about steam stripping of fusel oils:

Separation of Fusel Oils in Wine (PDF)

Perhaps the magic is the direct steam injection, or using the low-alcohol bottoms to generate "steam".

• Is that paper really "top secret?

StillDragon North America - Your StillDragon® Distributor for North America

• You can find it on a google search, download it from the WPI site, so I assume that if it was at one point, it's not anymore.

• edited December 2021

Even the scientists are scratching their heads at some of this, from that paper:

It was also found that separation times of 45-90 minutes or higher resulted in heavy components making their way into the distillate despite there still being light components in the residual. This was unexpected, and it is difficult to explain why this happened, however, it is our belief that with more experimentation this occurrence could be further analyzed. One possible explanation could be that the heavy components present in the distillate had been vaporized with the water that was contained in the fusel oils.

• edited December 2021

Another good one, which clearly indicates magic happening when fusels and fatty acids are brought together during distillation (the amyl alcohol esters are really interesting).

Constituents of Fusel Oils Obtained Through the Fermentation of Corn, Barley and Sweet Molasses (PDF)

Occasional presence of amyl esters of fatty acids seems to be the result of esterification of free fatty acids at some places in rectifying tower, since no amyl esters of higher fatty acids were found in fermented mash itself, the study of which is now under progress.

• @grim said: Even the scientists are scratching their heads at some of this, from that paper:

It was also found that separation times of 45-90 minutes or higher resulted in heavy components making their way into the distillate despite there still being light components in the residual. This was unexpected, and it is difficult to explain why this happened, however, it is our belief that with more experimentation this occurrence could be further analyzed. One possible explanation could be that the heavy components present in the distillate had been vaporized with the water that was contained in the fusel oils.

Hopefully they were not running the still incorrectly?

StillDragon North America - Your StillDragon® Distributor for North America

• Maybe, but I’m reading that in the same way as Todd Leopold talking about heavy, oily spirit.

• edited December 2021

@grim said: Maybe, but I’m reading that in the same way as Todd Leopold talking about heavy, oily spirit.

Hmm.
We sold em a CrystalDragon™ couple few years ago. I assume for this study?

Making vapor and getting good "plate behavior" can still be confusing. I mean I know its Gallo and all. But plated columns will absolutely drag more fusels over compared to a pot still.

You've talked about this at length before with respect to heavy RR for the sake of ABV and the confusion some people get when they try and wrap their head around why the 90% likker tastes so less than clean.

StillDragon North America - Your StillDragon® Distributor for North America

• I've got the COAs from an identical beer run through a pot still, 2 plate column and 6 plate column and there is a clear increase in fusel content running the 6 plate compared to either the potty or the tew plater.

StillDragon North America - Your StillDragon® Distributor for North America

• Also, that paper was ,,,,(hmm how do I say without sounding like a total dick),,,,easier to read than I was expecting,,,if you see my meaning?

StillDragon North America - Your StillDragon® Distributor for North America

• edited December 2021

Sure, but they were also just trying to remove water from fusel oil so they could use it as boiler fuel (Is this really a trade secret, hello bunker fuel?). I thought it was interesting because it's talking about dynamics we don't generally talk about, and dynamics that show that beverage distillation is far more complicated than we believe (or even understand), and that what we relegate to the ambiguous bucket of "tails", is actually far more interesting in how they react during distillation. We talk about 1 azeotrope, but there are likely dozens of meaningful binary and tertiary azeotropes that impact beverage distillation in really complicated ways. I also think there are tons of geometry related factors (or example, simple vapor entrainment carrying high boilers into the column where they might react unexpectedly in higher alcohol environments (high boilers getting to a place where they shouldn't theoretically be, participating in reactions that might not normally take place). That's something we've talked about - why high reflux under extended durations do not necessarily result in a more neutral spirit, in fact, the opposite usually happens due to ester formation in the column (completely counterintuitive). We talk about steam injection vs. other heating methods as being essentially the same, however, they absolutely have completely different impacts on the dynamics of distillation.

• edited January 2022

This is a great read and thread. I have been toying with the idea of having a helmet made up with a deep bed single large bubble cap that is approx 1.2m tall so that it will increase the temperature in the boiler. I calculated that it would increase the pressu by 0.088 bar which should increase the temperature here where I am at elevation 950m approximately 8 degrees celcius, which is very similar to what you will get from a three chamber still but as a clamp on helmet its going to be easier to run that than to run a three chamber still. I really want to do Irish pot still whiskeys with the same grain bills as they used 150 years ago but with a deep bed helmet to capture all the oils. If I get one made up I will post the results, with @Smaug's permission of course as its no SD gear.