How long shoudl a Reflux run take?

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How long shoudl a Reflux run take?

Postby grehund » Sun Sep 04, 2011 10:51 pm

I realize this is a pretty hard question to answer on it's own, as there's a HEAP of different variables. I'm hoping that some of you will be able to give me your examples so I can make some sort of comparison.

For example, my most recent run took over 13 hours. It was 11L @ 40% plus the additional water to fill the 25L boiler. I followed Husker's instructions for running a Boka, but upped the off-take drips/sec rate by 1 (averaging about 3-4 drips/sec). I would've pulled the pin earlier, but even after 13 hours I was still pulling a reasonable 93.5% purity in tails. My peak ABV was 95%.

Should I up the off-take rate some more, or is this kind of time-frame usual? :think:
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Re: How long shoudl a Reflux run take?

Postby R-sole » Mon Sep 05, 2011 3:22 am

I can't answer for anything cept VM, so probably not much help. What i do know is the common times will be in my case 1hr for heatup, 1 hour for equalization.

It takes me a couple of hours to bleed heads slowly, starting off at one or two drops a second for foreshots and slowly ramping up the takeoff till i have a broken stream at the end of heads takeoff.

Once hearts start though i can open my valve pretty much all the way, which will be 1 to 1.2l hour on a 2 inch and 4 to 5 l/h for a 3" till the hearts are all gone. I don't spend too much time collecting tails.
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Re: How long shoudl a Reflux run take?

Postby grehund » Sat Sep 24, 2011 2:20 pm

Thanks for the reply Punkin. That gives me a reference point at least.

Anyone with a LM Still got some info for me?
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Re: How long shoudl a Reflux run take?

Postby MacStill » Sat Sep 24, 2011 2:30 pm

LM is pretty close to what punkin has said for a VM, possibly LM you could bleed heads/fore shots a little quicker but not much.

I once did a 50L charge of 40% low wines and said fuck it after 16hrs, sold the still and built a 3" LM...... the same run was over in around 7hrs :dance:

2" might be cheaper but in the long run you'll be happy if you step up to a 3" column, watch it piss like a race horse :lol:
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Re: How long shoudl a Reflux run take?

Postby maheel » Sat Sep 24, 2011 2:32 pm

my last bok run maybe 8 hours

about 13L of low wines into the 2200w keg
topped it up to ? +-30-35L ?

bit over an hour to heat up
maybe 30 mins equalizing ?
a while trying to pull out the heads 40 mins

during my "hearts" i am pulling about 250ml every 15 mins (1L per hour ? )
it slows down a bit towards the end where i try to re-stablise as the heat creeps up a bit
then i lower heat input via PSR25 and slow collection rate keeping the temps stable

once the temps start moving again then open the valve to strip off some tails for the next run but
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Re: How long shoudl a Reflux run take?

Postby grehund » Sun Sep 25, 2011 11:16 am

Thanks McStill & Maheel,

Good info. It sounds like I might need to step up to a 3". I'll keep going for a little longer on the 2", still got heaps to learn!

I think I'll get someone to build a 3" for me. Any suggestions for a good builder in Vic?
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Re: How long shoudl a Reflux run take?

Postby R-sole » Sun Sep 25, 2011 11:55 am

We all ship mate ;)
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Re: How long shoudl a Reflux run take?

Postby busman » Sun Sep 25, 2011 1:36 pm

Grehund, can you swap out the element in your boiler? Reckon you'd get the job done heaps quicker if you could throw more than 1800W at it (? just a guess though, I have neither an LM nor an electric boiler, happy to be corrected)
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Re: How long shoudl a Reflux run take?

Postby MacStill » Sun Sep 25, 2011 1:41 pm

Good point busman, a 2" boka runs quite well with 2200w to 2400w & no controller ;)
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Re: How long shoudl a Reflux run take?

Postby Tracker » Thu Sep 29, 2011 12:48 pm

Main point is to adjust your water speed/volume/pressure whatever until the output water from your coil is hot to the touch but no vapour escaping.
With the 2" bok, run it slow for a start, 3 or 4 drops per second until you get out of the foreshots, increase slightly to get through the heads.
Once at that point, do not lower the heat input but you can increase the product take-off rate to maintain a head or upper column temp of around 79C max., as the temp rises, slow the product take-off down, if it drops, open the tap a little. On a 2" bok you should be able to run most of the hearts off at a fine or broken stream.
By the end of the run you will not be able to close the tap any slower to keep the temp below 80C by which time you will be at the tails and you may just as well open everything up and strip the rest as fast and for as long as you want.
This method will result in a very slight loss of %abv, no perceivable taste difference but a lot less time sitting on your arse.


Cheers.
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Re: How long shoudl a Reflux run take?

Postby grehund » Sat Oct 01, 2011 12:58 pm

Thanks for the extra info & advice guys. I'm doing a reflux run today, so I'll give it a try.
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Re: How long shoudl a Reflux run take?

Postby maheel » Sat Oct 01, 2011 1:36 pm

Tracker wrote:Main point is to adjust your water speed/volume/pressure whatever until the output water from your coil is hot to the touch but no vapour escaping.
.


hey Tracker i was wondering why you adjust your flow of cooling water, whats your reason for that ?

i dont bother adjusting water flow, just let the pump run flat out and use ALC temp to adjust the take off rate
but i mostly use the same idea of controlling the ALC temp like in your post
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Re: How long shoudl a Reflux run take?

Postby R-sole » Sat Oct 01, 2011 3:12 pm

The idea is to cool the reflux to just above vaporisation temp. You want to use the efficiency of the packing for it's full length rather than have cooled condensate soaking the packing down it's length that you then have to bring back up to temp.
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Re: How long shoudl a Reflux run take?

Postby maheel » Sat Oct 01, 2011 3:37 pm

@ punkin

why do people then put centering rings in the column ?

and although i kind of understand what your saying Punkin, if you do not have reflux running back down through the packing (to some degree) how are you getting the it to reflux. Wont everything in the bottom of the column just be going "up"

if your just refluxing in the top area whats going on in the middle ?
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Re: How long shoudl a Reflux run take?

Postby R-sole » Sat Oct 01, 2011 5:13 pm

People put centering rings in their columns to stop the possibility of reflux channelling down the sides of the column wall and to spread the reflux evenly throughout the section of the packing to allow for the maximum possible amount of surface area being wet and therefore being revapourised.

You need reflux running back down the column and you will always have the same amount of liquid running back down at the top as volume of vapour being produced in the boiler (minus what you are taking off) but if the liquid is as close as possible t0 the temp of vapourisation, the less work the column is doing and therefore the more efficient it is.
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Re: How long shoudl a Reflux run take?

Postby SBB » Sat Oct 01, 2011 5:51 pm

Soooo to some degree you are using CM to maximize efficiently with a VM or LM :icon-eek: :crazy: :crazy:
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Re: How long shoudl a Reflux run take?

Postby maheel » Sat Oct 01, 2011 5:58 pm

Punkin do you think slowing the water down improves performance of "any" still (that being quality and % alc) or is it only really improving the efficiency of input to outputs.
that being if i throttle back the cooling i will see improvements in possibly quality, takeoff rates and purity.

i am not saying your wrong but i would have thought and condensation at the cooling point would drip back down at +- the same temp regardless of the temp of the cooling water at the coil assuming nothing but "water tension" is holding it to the cooling device and that "warming" the cooling device allows vapor to travel further up the coil and that may actually reduce the temp of the condensation more than if it hits the bottom and falls from there.

i am thinking of my BOK or other "like" reflux types no really plates as i dont really have a understanding of how they operate.

interesting discussion :) gone OT but :doh:
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Re: How long shoudl a Reflux run take?

Postby R-sole » Sat Oct 01, 2011 7:25 pm

No, i don't think that it works like that.

I'm not strong on the theory, but it's solid working theory.

I like to just copy a design that works, operate it within reasonable takeoffVpurity compromise that works for me.

A lot of people who like vodka a lot more pure than i do fuck around with all this stuff and write books and discussion papers. This is what they say (pr what the people who are intersted enough to read and digest the science say).


A little reading of some of the theory threads on Artisan in the reflux section will satisfy your thirst without me trying to regurgitate stuff i didn't really put the effort into understanding in the first place.

Minime is your goto guy, pm him and point him to this thread. ;)
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Re: How long shoudl a Reflux run take?

Postby Tracker » Sat Oct 01, 2011 9:08 pm

hey guys, I am talking about how I found it best to run my 2" Bok.
Yes, the designer says to run it at 3 to 4 drops per second. Thats fine if you want to go to sleep watching drips fall from a tiny little pipe for an hour for a small quantity of product.
I have better things to do with my time and it can be run somewhat faster for a small sacrifice in quality.
Please do not confuse what I do with all other reflux columns because like women, they all have different temperments.
All you have to do is to try my method with your Bok for one run. If you can tell the difference then don't do it any more.

The thing with reflux is that you don't want to send all of your condensate all the way back to the bottom of the column. The idea is to lower the temp slightly so that the unwanted (tails section) falls out of the column back into the boiler but the desired fraction ie heads, then hearts stay up the top of the column, so that they are the first out of the product take-off line. So for this to happen, you only need to lower the refluxing temp to just below the highest temp required to send the tails back down but not the hearts, this is what gives you the seperation of the componants.
If you had numerous temp probes up the column you would find that there is a constant gradual temp grade which keeps the different fractions in their place and as other lower fractions rise into the column, the higher temp fractions drop back into the pot.
This explains the process of equalising the column because this is exactly what happens and how you can get rid of the foreshots at the start of the run.


Cheers.
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Re: How long shoudl a Reflux run take?

Postby Tracker » Sat Oct 01, 2011 9:24 pm

As an afterthought as to why you do not want to over-cool the reflux coil.
If the cooled product finds it's way down to the boiler, it gets mixed back up with all of the other componants and you need to start the process all over again.
If you can keep things warm enough within the column, the various fractions will begin to stack up on top of each other.
This stacking up explains why, if the temp rises, this shows that the higher temp componants are rising up the column so you reduce the take-off speed to allow for more of the desireable fractions to get back up to the top of the column.
Column temp is low - you can speed up the take-off.
Column temp is high - slow down the take-off speed.


Therefore, keep your condensing coil exhaust water hot, not cold.


Exactly the opposite to what you would do with a pot still condenser.
These are the things which newcomers find it difficult to comprehend, along with such things as you cannot heat up a wash containing alcohol above 80, 85 or 90 C regardless of how much heat you throw at it.


Cheers.
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