Question about reflux

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DVW70
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Question about reflux

Post by DVW70 » Sat Feb 18, 2017 1:31 pm

So I have a 5 gallon still kit. The column is 1.5" diameter and about 14". I have,packed,it with copper, but after about 250 gallons of sugar wash runs I notice that saturation occurs because I cannot get the gas input low enough to keep the reflux working. I used a steel plate below the still, but really I need a better burner or lower it physically so there is no flame impingment.

With no packing, or with packing my 2nd run nets 85% ABV, cannot do any better.

My question is if I wrap the Outside with 1/4 copper, soldered solid to the outside of the column, would there be sufficient reflux off the walls,of the column to make a difference. Rather then dismantling and rebuilding the column for an internal coil?

StillerBoy
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Re: Question about reflux

Post by StillerBoy » Sat Feb 18, 2017 1:36 pm

The short answer why only 85% abv is your column is to short.. need at least 24" of packed column to get 90+..

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BayouShine
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Re: Question about reflux

Post by BayouShine » Sat Feb 18, 2017 1:37 pm

Sounds to me that you have a pot still with packing. What are you using for a reflux condenser?

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Re: Question about reflux

Post by Badmotivator » Sat Feb 18, 2017 1:48 pm

It would help a little, and would pretty easy and harmless to try. Combine a little active reflux with a much longer column and you'll definitely see the improvement. A wider column (so you could run faster) and reflux that isn't all on the walls would help too.

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Re: Question about reflux

Post by Bushman » Sat Feb 18, 2017 2:03 pm

Pictures of your set-up and members can give you better answers.

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Re: Question about reflux

Post by Pikey » Sat Feb 18, 2017 2:14 pm

As badmotivator says, It can't do any harm. - But as Stillerboy says - 14" column for 5 gallons is just too short.

A photo would help us to see it, but I'd still like to hear 40" ! Maybe a little less, I'm no reflux expert but plenty here are. :)

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Re: Question about reflux

Post by still_stirrin » Sat Feb 18, 2017 2:32 pm

The design goal for a reflux still is L/D = 20/1. So for a 1-1/2" ID, you'd (theoretically) need a 30" tall column (packed section). And remember, speed of vapor production is proportional to the ID of the column, not the height or the capacity of the boiler. All of these design fundamentals are available in the parent site.
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Re: Question about reflux

Post by Pikey » Sat Feb 18, 2017 3:53 pm

Thanks for that ss - I'm picking up a potential new boiler on Monday and have 5 metres of 2" copper, so that seems to equate to around 55" of column o/a :( - Not sure I'm going to have the headroom ! :roll:

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Re: Question about reflux

Post by rad14701 » Sat Feb 18, 2017 4:37 pm

Pikey wrote:Thanks for that ss - I'm picking up a potential new boiler on Monday and have 5 metres of 2" copper, so that seems to equate to around 55" of column o/a :( - Not sure I'm going to have the headroom ! :roll:
For a 2" column you'll want between 36" - 42" of packed column section... Less will reduce the purity capability and more will result in diminished improvement of performance... Those numbers are based on years of practical application by a multitude of members... You could always add a column extension down the road if you really feel the need but I highly doubt it would ever be required... Column packing selection would make a greater difference than additional packed section height...

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Re: Question about reflux

Post by Pikey » Sun Feb 19, 2017 7:19 am

Thanks rad - It depends how tall the pot is and all that stuff, how much height I can spare. I'd already thought if I cut the column and have a section of 10-12 " or so which I can just slot in, that would allow me to run pot mode and move the kit if I need to for reflux - I'll start a thread in boilers when I get it back and work out size, capacity etc. 8)

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Re: Question about reflux

Post by still_stirrin » Sun Feb 19, 2017 12:22 pm

Pikey,

Having a selection of differing length spools is quite handy. You can select the combination of columns to target the desired product proof...longer for cleaner, more neutral products and shorter lengths for more flavor with yet a "higher than potstill" proof. Experience will teach you which combination is best suited for the desired products and processes.
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Attention new distillers: Cranky's spoon feed info
My LM/VM & Potstill: My build thread
Enzyme info: SebStar
All about mashing grains: Braukaiser

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