Continuous still brainstorming

[Lester]

Lester, how long can you run your still at maximum take off before going into full reflux?

It depends on what's in the boiler.

With 40% low wines I can get about 1 liter out continuously, in less than 15 minutes (~4 liters per hour), after stabilizing for 10~15 minutes. This is the start of the hearts cut.

With 12% wash, at the start of hearts: about 200ml, then I have to reflux.
With 12% wash, but when the wash has dropped to about 7% ABV: about 150ml, but this depends on how long I refluxed before taking out product. If I wait for a short while then I only get 50ml out. At 2% ABV I have to wait forever.

This is why I said: It takes a finite amount of heat & time (Energy) to boil off a finite amount of alcohol in the wash. No shortcuts to this phenomenon. I have run my still >30x, 19-liter batches of 12% ~ 14% ABV, and it always behaves like this.

[Jacksonbrown]

[td][attachment=0]continuous still.png[/attachment][/td][td]When you stack the sections of a continuous still on top of each other you get what is shown to the left. Now we need to take off the fusel oil in the lower section of the rectifier column. What leads to the question of how to control the rate. Lester showed us [url=http://homedistiller.org/forum/viewtopic.php?f=1&t=44848]his way[/url] to take off as much distillate as possible and when the vapor temperature went a little bit up to go into full reflux for a minute or two. I just wonder if the same can be done with a continuous still: close the ethanol take off and open the fusel oil take off to flush the content of the column when the fusel oil concentration becomes to high? Lester, how long can you run your still at maximum take off before going into full reflux?[/td]

In that layout all of the heads fraction needs to travel passed the the ethanol take off point. Do we assume that none will condense and contaminate the middle cut?
That's the problem I was referring to in my last post. Have I missed the point?

[badbird]

Do we assume that none will condense and contaminate the middle cut?

Some of the existing commercial systems appear to feed the ethanol cut into a second small column with its own heat feed to deal with the remaining heads. There are some diagrams around some where on google nut cant find at the moment

[Jacksonbrown]

Do we assume that none will condense and contaminate the middle cut?

Some of the existing commercial systems appear to feed the ethanol cut into a second small column with its own heat feed to deal with the remaining heads. There are some diagrams around some where on google nut cant find at the moment

That's kind of along the line that I've been pondering only built into the one system.

It's funny, every time I think up something it seems someone else has done it somewhere. I built an inline slant plate head over 8 years ago and thought it was a great way around the build complexity of a offset NS LM head by adding a small weir. it seems some guy named Alex had the same idea a few years prior

[heartcut]

Here's one resolution to the problem of adding character to your spirits. Think of the trays as the equivalent of distilling time in a batch still, like in the attached. A blend to your own preference is just as possible as in batch distilling.
Edit Flow control on the trays is by the standpipe for the product out being a little lower than the downcomer.

[badbird]

Jacksonbrown, The only problem i can see with the layout in your PDF is that there will probably be some tails coming into the main column above the hearts takeoff. Difficult to nut this stuff out without serious modeling software 'or building it'

A blend to your own preference is just as possible as in batch distilling

The bunker still guys claim you can do that by blending just the hearts and lighter tails, although i know a few rum drinkers that say it rubbish without a bit of heads burn I am thinking about making up a few 2" modular bubble cap plates with outlets like yours (and packed sections between) to clamp on the top of the stripper and see what happens. Just don't have either time or copper spare at the moment.

[Edwin Croissant]

In that layout all of the heads fraction needs to travel passed the the ethanol take off point. Do we assume that none will condense and contaminate the middle cut?
That's the problem I was referring to in my last post. Have I missed the point?

I don't expect that the high volatiles will condense lower in the column. The top section of the rectifier separates the high volatiles and the ethanol. How much separation is achieved depends of how high this section is. I think that for Acetaldehyde you need a short section, for methanol you need a much higher column due to the low relative volatility compared with ethanol.

The way this setup works (I hope ) is that the most volatile vapors rise to the top of the column. They accumulate there and cycle between the ethanol vapor and the condenser. The ethanol vapor with it's higher temperature will evaporate the higher volatile liquid and condenses in the process. The top section of the rectifier separates the ethanol from the higher volatiles, the higher volatiles come out from the top and the ethanol from the bottom. The bottom section of the rectifier separates the water from the ethanol, here the ethanol come out from the top and the water from the bottom. A special case is fusel oil. Fusel oil is more volatile as ethanol at low ethanol concentrations but less volatile then ethanol at higher ethanol concentrations. So the fusel oil gets trapped in the column and must be taken of at the point of the highest fusel oil concentration.

Some of the existing commercial systems appear to feed the ethanol cut into a second small column with its own heat feed to deal with the remaining heads. There are some diagrams around some where on google nut cant find at the moment

I have seen diagrams were the take off point of the high volatiles was located above the ethanol plate or was vented to the atmosphere, I have seen a hobby scale continuous still were first the ethanol was condensed and later evaporated to get the higher volatiles out. It looked to me that the extra column was an afterthought.

[Jacksonbrown]

Sorry to dig up an older one but I saw this the other day and though it was relevant.

Perrys chemical engineer’s 8th handbook.pdf

(66.31 KiB) Downloaded 220 times

It looks a lot like what I was suggesting a while back and it goes on to a lot more configurations along the same lines too. It might be of interest to some.

I downloaded Perrys 8th edition a while back, maybe off a link I found on here somewhere but I can't seem to find it now and the whole PDF is too big to put up.

[googe]

Found it badbird, took some digging!!. Not a great experiment but just sharing. http://www.aussiedistiller.com.au/viewt ... 9&start=20" onclick="window.open(this.href);return false;" rel="nofollow