Varying sizes in a column - effect?

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EricTheRed
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Varying sizes in a column - effect?

Post by EricTheRed »

Hi

So following on from my question yesterday (being true vertical), i have another regarding difference sizes of column in the same setup

the setup
* 30 Litre boiler with domed lid
* 2" bulkhead adaptor - with a 38mm opening
* 2" to 3" adaptor (not packed)
* 70cm 3" Column
* 3" to 2" adaptor (not packed)
* 90cm 2" column (only in reflux mode)
* 2" deflag (only in reflux mode)
* 2" 90° (x 2)
* 60cm 2" shotgun condensor
* 2" to 1/2" copper adaptor
* 1/2 copper pipe to collection jars

Now, the questions are these
a) will the mix of sizes have a detrimental effect on the process?
b) will there be undesirable turbulence as the sizes change?
c) should the larger 3" be after the 2"?
d) should i pack the adaptors as well? They are about 10cm long with most of it 3" diameter

I used to run a 2" packed column/riser in pot mode - but switched to 3" - and my ABV has gone up as a result of that.
I run it as above in reflux mode

ABV on spirit runs - pot mode, only 3" riser - starts at around 88% for about 3 - 4 litres, then slowly starts to drop
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Re: Varying sizes in a column - effect?

Post by OnceAlive »

Hi EricTheRed

I'm sure that many will agree that a picture would be of tremendous help to visualize your setup. I would personally draw my understanding of your description to see it but a photo would be much faster and accurate.

Morning cheers!

Edit addition: I don't have a reflux column yet but in my research on them I understood that everyone should be able to reach the 90% mark pretty easily. If your getting 88% with all that length of column I would suspect that you don't have enough reflux. It seems to me taht you make vapor travel a very long way (maybe too much), you're able to knock it down with the shotgun but the separation of water and alcohol is not done properly.
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Re: Varying sizes in a column - effect?

Post by still_stirrin »

EricTheRed wrote: Thu Jan 13, 2022 12:04 am Hi

So following on from my question yesterday (being true vertical), i have another regarding difference sizes of column in the same setup

the setup
* 30 Litre boiler with domed lid
* 2" bulkhead adaptor - with a 38mm opening
* 2" to 3" adaptor (not packed)
* 70cm 3" Column
* 3" to 2" adaptor (not packed)
* 90cm 2" column (only in reflux mode)
* 2" deflag (only in reflux mode)
* 2" 90° (x 2)
* 60cm 2" shotgun condensor
* 2" to 1/2" copper adaptor
* 1/2 copper pipe to collection jars

Now, the questions are these
a) will the mix of sizes have a detrimental effect on the process? <— Probably not, depending on what you mean by “detrimental”. Changing sizes in the vapor path will cause a change in the velocity of the vapor because the mass flow of the vapor is constant and a diametral change affects the “flow area” the vapor passes through. And flow velocity affects the vapor’s static pressure, again this affects the density of the vapor and that can alter the boiling point of the vapor, or the vapor’s constituents.

b) will there be undesirable turbulence as the sizes change? <— Probably not. Optimal vapor production rates will keep the vapors flowing well below “turbulence”. In fact, the vapors will be quite laminar until they approach sonic speeds, which can happen in a small diameter pipe that is long (a worm, for example).

c) should the larger 3" be after the 2"? <— The “larger after the smaller” diameter of pipes will hold temperature better than the converse, again because of the increased velocity in the smaller pipe diameter.

d) should i pack the adaptors as well? They are about 10cm long with most of it 3" diameter<— It wouldn’t hurt. It would minimize the “abrupt” flow area change imposed by going from a pipe “with packing” to a pipe “without packing” and then back into a pipe “with packing”. This flow area change causes static pressure differences which can affect the temperature of the vapor.

I used to run a 2" packed column/riser in pot mode - but switched to 3" - and my ABV has gone up as a result of that. <— This is not surprising, because you’ve slowed the vapor velocity down in the vapor path. This will cause the less volatile constituents (H2O) to condense sooner and fall back down the pipe.
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Re: Varying sizes in a column - effect?

Post by Demy »

I agree with stillstirrin
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Re: Varying sizes in a column - effect?

Post by EricTheRed »

OnceAlive wrote: Thu Jan 13, 2022 5:29 am Edit addition: I don't have a reflux column yet but in my research on them I understood that everyone should be able to reach the 90% mark pretty easily. If your getting 88% with all that length of column I would suspect that you don't have enough reflux. It seems to me taht you make vapor travel a very long way (maybe too much), you're able to knock it down with the shotgun but the separation of water and alcohol is not done properly.
I am getting 88% ABV on pot mode - not reflux :)
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Re: Varying sizes in a column - effect?

Post by EricTheRed »

SS
as always - you explain things nicely

for OnceAlive - i'll take a pic of the setup in POT mode tomorrow - once i'm done the spirit run tomorrow, i'll add the extra column and take another :)
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Re: Varying sizes in a column - effect?

Post by still_stirrin »

EricTheRed wrote: Thu Jan 13, 2022 6:07 am
OnceAlive wrote: Thu Jan 13, 2022 5:29 am Edit addition: I don't have a reflux column yet but in my research on them I understood that everyone should be able to reach the 90% mark pretty easily. If your getting 88% with all that length of column I would suspect that you don't have enough reflux. It seems to me taht you make vapor travel a very long way (maybe too much), you're able to knock it down with the shotgun but the separation of water and alcohol is not done properly.
I am getting 88% ABV on pot mode - not reflux :)
You have a 1.6 meter tall packed riser with diametral changes. So, even without a reflux condenser, you are getting some water condensation from your vapor. But, I wouldn’t call it “reflux” because reflux is condensation followed by reboiling over and over multiple times. The reflux action separates the volatiles from the non-volatiles.

But, you are getting some “scrubbing” of the lower volatile constituents due to the long path and the packing (which pulls heat from the vapors).
ss
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Re: Varying sizes in a column - effect?

Post by EricTheRed »

Ss
In pot mode - 70cm packed
In Reflux 1.6m packed + dephlemator
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Re: Varying sizes in a column - effect?

Post by EricTheRed »

For OnceAlive - the pics of it setup in POT mode - with items in green where i would insert the bits (90cm packed column and Dephlegmater)
image.png
Ignore that pressure gauge - that is only used when the boiler is used for pressure canning (SWAMBO and I share various bits of kit :) ) - but kind of handy as a warning should i get a blockage! :)

The temp gauge at the top is only for record keeping - not used for anything other than letting me know when the run is about to start. I do of course record the temps every 300/500/900/1000ml and i can predict ABV pretty close using historical datasets :)
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Re: Varying sizes in a column - effect?

Post by still_stirrin »

Eric,

Is your canning pressure vessel actually stainless steel?

Most I’ve seen that size are cast aluminium, which would NOT be good for use as a boiler. I know you’ll use “what you have” anyway, but I just want to point out the concern/danger of using the wrong materials in a still.

Safety first!
ss
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Re: Varying sizes in a column - effect?

Post by EricTheRed »

304 stainless steel
We were very particular about this, ss or nada.
Appreciate the concern, but we good
:)
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Re: Varying sizes in a column - effect?

Post by OnceAlive »

EricTheRed wrote: Thu Jan 13, 2022 6:07 am I am getting 88% ABV on pot mode - not reflux :)
Oh! Ahh! HAHA! Forget what I said then! :D
EricTheRed wrote: Thu Jan 13, 2022 11:44 pm For OnceAlive - the pics of it setup in POT mode...
Wow! That's a sweet setup! And it makes your initial description really clear, thanks.
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Re: Varying sizes in a column - effect?

Post by EricTheRed »

Just finished a grain sugarhead spirit run, 29 L charge at 31%, 10 hours.
900ml increments, jar 1 = 85% jar 17 = 10%. Avg 66%
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