## Re: My reflux column

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• I agree totally with this statement, had the same issue and when I increased the heat, got some good stuff, it s all about the reflux, make sure the column has
Message 1 of 32 , May 2, 2012
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I agree totally with this statement, had the same issue and when I increased the heat, got some good stuff, it’s all about the reflux, make sure the column has stabilized prior to takeoff.

I had a similar problem with purity, turning the heat down and down to see what happened, till eventually nothing came out the column. I found that increasing the heat actually gave me a purer product. I think what was happening at a certain temperature the column was acting only as a fractionating column not a reflux. All or most of the distillate at the top of the column was being taken off before any reflux was taking place. The cooling water was only tepid. When I increased the heat I then got the reflux I was after and the purity went up. The temperature of the cooling water also went up to 50-60c. It is a fine balancing act, but as your cooling water is not warm the condenser may not be getting the hot vapors?
Regards
Dave E

• Gavin, If you are trying to get to the azeotrope starting with 10% abv beer, the minimum reflux ratio that you need is 2.4:1. This means that for every 1
Message 32 of 32 , May 8, 2012
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Gavin,

If you are trying to get to the azeotrope starting with 10% abv beer, the minimum reflux ratio that you need is 2.4:1.  This means that for every 1 liter of product that you take off, you need to send 2.4 liters (or about 70% of the liquified vapor) back down your column.  Theoretically, to achieve this minimum you need an infinite number of plates; in practice, you can get close enough to azeotrope that you can't measure the difference with around 25 theoretical plates.  To a limited degree, you can reduce the number of plates and still get the same proof by increasing the reflux ratio.  At 100% reflux, you can get aeotrope with about 7 plates from a 10% beer (but of course 100% reflux gives you no product and is only useful as a science fair project).  Nixon and McCaw advocate short columns and around 90% reflux (10 liters down the column for even one that you take off).

This is all dictated by the laws of physics.  The only ways around this are:
- increase the proof of your beer (decreases reflux for azeotropic product)
- reduce your product purity requirement (reduce the required proof of the product)

You can also use these same figures and increase your product production rate by increasing the boiler power, but only if you correspondingly increase your condenser heat removal capacity (to maintain the reflux ratio needed for your HETP), and making sure that your column diameter is sufficient to maintain vapor flow up the column at a resasonable rate (12 - 20 in/sec; calculated as I described in an earlier posting).

Note that when you start your batch still off with 10% abv, it won't stay this way.  As product comes off, the %abv of the beer must reduce and therefore you need to monitor still head temperature (as a proxy for proof) throughout your run and as you see the temperature increase, you must increase your reflux rate to get back to azeptrope (or whatever proof you desire).  At some point, your reflux ratio will be so high that you decide that it isn't worth it anymore and you will stop the run and use the low wines on a subsequent run.

Get you column into equilibrium and keep it in equlibrium at all times!!!  This is what reflux distillation is all about.  Patience is the watchword here.  If you don't have the patience to do this, get yourself a high quality continuous still and then once you get it up into equilibirium and establish the required minimum reflux ratio, you can just leave it there without further adjustment (which doesn't mean unattended -- you are making a highly flammable fuel, regardless of what you actually intend to do with it later :-).

Bob

-----Original Message-----
From: Gavin Flett <gavin_flett@...>
To: new_distillers <new_distillers@yahoogroups.com>
Sent: Mon, May 7, 2012 10:48 pm
Subject: RE: [new_distillers] Re: My reflux column

```Just an update on the run Bob. I have tried it with 450W, 600W and 900W of
power, I have tried a 2:1, 1:1 and 1/2:1 reflex ratio. Everything that I do
achieves 92% ABV, so I am thinking that it is my packing that is preventing
further purity. Or, maybe it's my alcoholometer that is faulty....

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