Continuous still brainstorming

[forty three 2]

On the subject of methanol removal, I was wondering what the feasibility of having 2 takeoff points would be. So on the hobby scale something like (from the top down):

the condenser
top boka
6-12 inch packed column
bottom boka
long packed colum
rest of the continuous still (wash introduction, lower packed column, boiler, waste removal, etc)

Would this allow you to take off methanol from the top boka (very slowly or in predefined amounts every so often) and good product from the bottom? I'd imagine most of the methanol would travel up past the lower boka and stay in the upper section then you could drain out the upper boka to remove it. I suppose some of the methanol would drop into the lower boka but perhaps it would be an acceptably small amount? I also think insulating the lower boka would be important to avoid it acting as a cool area that collected methanol. Might this work or am I missing something important?

[Edwin Croissant]

Ok for anyone interested I found FermCalc here http://web2.airmail.net/sgross/fermcalc ... sions.html
It will change ABV to ABW and vice versa.
It claims to use this in its calculations (Edwin I am guessing this is the recommendation 22 in your paper?)

Thank you for the link. Recommendation 22 is indeed the paper I am referring to in my paper.

On the subject of methanol removal, I was wondering what the feasibility of having 2 takeoff points would be.

I think this will work for Acetaldehyde, Ethyl acetate and Diacetyl etc. For Methanol you need a much taller column due to the relative low volatility of Methanol of 1.7 in respect to Ethanol.

[dullfig]

I think this will work for Acetaldehyde, Ethyl acetate and Di-acetyl etc. For Methanol you need a much taller column due to the relative low volatility of Methanol of 1.7 in respect to Ethanol.

I keep wondering about that, since in the diagram for the Coffey still, they show the ethanol removal point to be just 8 trays below the top. If you look at the diagram for the distribution of products in the column, it shows methanol as negligible at the eighth tray from the top. am I not reading this right?

[dullfig]

This might be a moot point if you're distilling sugar mash I believe, as the amount of Methanol is very small, if I'm not mistaken.

[flyingdutchman]

One thing to consider with the coffee still is its actual size and number of plates..
http://en.wikipedia.org/wiki/File:Coffey_Still.JPG

That's not to say other members here have not built heads traps. Myles might be as very good person to ask about these.

[dullfig]

One thing to consider with the coffee still is its actual size and number of plates..
http://en.wikipedia.org/wiki/File:Coffey_Still.JPG

I think I'm going to need a bigger garage...

[flyingdutchman]

LOL good one!

[heartcut]

No problem. Just put together a 30 tray still and see how it works. Mine has 2- I'm feeling insecure.

[DAD300]

Bundaberg, uses a continuous stripping still to create low wines.
http://www.youtube.com/watch?feature=pl ... 40Q72PYBok" onclick="window.open(this.href);return false;" rel="nofollow about 9:30 shows an animation.

They use a few of the ideas you've been kicking around. Like agitation...they agitate the wash by dropping it into the top of the still column and flopping it back and forth over weirs during decent. As it drops through the still the ethanol vaporizes (I assume due to a temp gradient) at different points and the water continues on to the bottom.

It looks as though they use a steam jacket to heat the outside of the column. Then the pot at the bottom does nothing but collect the waste.

It is more like Lester's drawing...but (Lester please excuses my grabbing your drawing).

This for me...helps define a better separation between wash and throwing out the waste. It might also eliminate the pump issue. The metering of the wash injection shouldn't be so touch...drops per second.

The weirs could be any type of packing...maybe even scrubbies.

Wash tank to wash resevoir would be a non critical pump or gravity. Resevoir to column could be gravity metered by valve.

If you had to use a dosing pumps...I use them in my home water purification system to inject chlorine. I get the pumps used off ebay for $30-60usd and rebuild kits for about $30usd. http://www.ebay.com/itm/LMI-Milton-Roy- ... 27d44498b5" onclick="window.open(this.href);return false;" rel="nofollow

I rebuild them because I don't know what they were used for before I got them.

What I labeled as STEAM JACKET doesn't have to be steam. Could be a electric heat strip, water or glycol bath.

[Jacksonbrown]

I’d appreciate some input on this one. Obviously it's only good for stripping.

I already have two 2”x500mm shot guns and 2.2kW RIMS tube plus all the rest of the bits pictured.


I’m hoping I can slow the flow through the system with the pump throttling valve.
With my control system I can manually set the power output from 0 to 100% in 0.1 increments or set it to PID mode, so lots of control there. I can also get the read out of the temp so 98°C should mean it’s working, I guess.

The things that I’m concerned about are –
How much head do I need to stop the column flooding as the distillate path is still open to atmosphere (I should see if this is happening through the sight glass)
Do I need some sort of chamber at this point to help shed the vapour?
Assuming no regen, for 2.2kW to bring 10% wash down to 2%/3%, what flow rate should I expect? And what about with the two HEXs and cladding on the lot?

This would be quite easy for me to do with what I have at hand but would it work or is there something blindingly obvious that I’m missing?

[Jacksonbrown]

How do I get PDFs to display in-post?

This is along the lines of what I was thinking.

It might get around max boiler size regulations too

[badbird]

Jackson, Just few thoughts...
I think you will struggle to get good results injecting at the base of the column, it flies in the face of tradition anyway .

I have tried liebigs as wash heaters, they tend to fill up with vapor and surge and choke..., Shotguns may well be the same but only one way to find out.

A positive displacement wash pump is a good investment, Gravity feed just don't cut it when trying to force wash through a vapor choked heat exchange.

[badbird]

Probably most people have already seen it but Bunker stills version of a continuous still is worth a look. There was a discussion about it over on the ADI forum a while ago, a couple of useful hints on packing etc where dropped. http://adiforums.com/index.php?showtopic=3559

[Jacksonbrown]

The wash flows past the column. From that point up its a normal system. the rims tube is just acting as a continuous boiler. that's the idea anyway.
I will be feeding it with a pump and I'm hoping the correct layout can prevent gas buildup/airlock.

[Edwin Croissant]

Bundaberg, uses a continuous stripping still to create low wines.
http://www.youtube.com/watch?feature=pl ... 40Q72PYBok" onclick="window.open(this.href);return false;" rel="nofollow about 9:30 shows an animation.

They use a few of the ideas you've been kicking around. Like agitation...they agitate the wash by dropping it into the top of the still column and flopping it back and forth over weirs during decent. As it drops through the still the ethanol vaporizes (I assume due to a temp gradient) at different points and the water continues on to the bottom.

It looks as though they use a steam jacket to heat the outside of the column. Then the pot at the bottom does nothing but collect the waste.

Thank you for the link , I was just in time to watch, video is removed now.
IIRC, the stripper is fed with steam from the bottom, can't check the video now but the stripper in another video from this company is also fed from the bottom with steam (at 5:23).

The stripper looks rather large, Bundaberg produces 60k bottles of rum each day, equals to ~ 42k liter rum, equal to ~ 168k wash. A Guillaue-Egrot apparatus from a century ago was capable of processing 30k of wash a day. That giant stripper could then be replaced with 6 of these :

Treatise on general and industrial organic chemistry (1921) page 163

Probably most people have already seen it but Bunker stills version of a continuous still is worth a look. There was a discussion about it over on the ADI forum a while ago, a couple of useful hints on packing etc where dropped. http://adiforums.com/index.php?showtopic=3559

Their still gave me the confidence that this could be feasible project. Regarding the heat exchanger, would it not be possible to use a small plate heat exchanger? In stainless steel (20 kW capacity) are used here in the Netherlands in our central heating systems for providing hot tap water.

In general, for hobby scale, is a continuous still of processing 12 liters of wash (~ 1kW) per hour large enough?

[heartcut]

One way to look at this would be multiple takeoff points would be stacked in the same way that collection jars are used for a batch still. I think 8 trays or ~48" of packed column with temperature controlled center feed and multiple takeoff points would accomplish this. The hard part would be controlling the flows at these points. A stand pipe shorter than the downcomer might work as a cheap flow control device, keeping liquid on the tray and taking the excess.
For hobby level, quantities would be whatever you wanted to ferment- just run it till it's done. That would negate the objection that the still would have to be small or the ferment large. Edit- a continuous still doesn't need to be a 24hr operation, that's just a description of the feed method.

[DAD300]

"Is 12 liters of wash an hour enough?"

Times 24 hours a day - ~288 liters (starting at10%) of was a day = ~28 liters a day of low wines (~40%) = ~14 liters of 80%-95% = ~28 liters of finished product.

Two weeks ago you started a 288 liter ferment (the first). Now start a 288 liter ferment every day.

Day 14, you stripped the first 28 liters of low wines and started another ferment.

Tomorrow you start another ferment while you stripped another 288 liters and rectified to 28 liters.

That's a little optimistic, quick and dirty...but after a month, the question becomes is 28 liters of product a day enough? Is 28 liters x 30 days, or 840 liters of drink a month, enough? The question becomes, "Enough, for what?"

Thus a catch 22 of a small continuous operation...

[Edwin Croissant]

"Is 12 liters of wash an hour enough?"

Edit- a continuous still doesn't need to be a 24hr operation, that's just a description of the feed method.

Right! Let me rephrase the question.

Maritimer writes iirc that he uses batches of about 100 liters. If you want to spent 10 hours at the most 10 l/min intake ( > 1 kW still) will do that. If you are making 30 liter batches a still which can process 6l/hour the run will take 5 hours.

So what is a "normal" batch size and how long do you want to spent on the distillation process?

[heartcut]

I do 45 liter batches in 3.5 hrs after getting up to a boil which is the equivalent in time of a continuous feed at 13 l/hr.
Edit: 45 l or 12 gal is a common batch size for keg boilers.

[badbird]

The Bunker still guys appear to do it all with one column and a very stable temperature gradient! hmmm
Has any one seen any photos of their still apart from the lopsided one on their website that only shows the bottom two thirds ??

Is 12 liters of wash an hour enough?

I found the 9 or so liters an hour throughput from the stripping column to be adequate for me as with the short heat up it can be stopped and started as time is available. Also as i run it out where it cant cause to much trouble and the only flammables are those contained in the column at the time I don't supervise it nearly as closely as the regular gear.

small plate heat exchanger?

Just goggled these as i have not come across them before. They look quite good, the bolt up ones look easy to clean if the get gummed up by dirty wash but will probably have the same problems with vapor locks and surging. Will keep an eye out for a SS one at the right price.

[Edwin Croissant]

Badbird, heartcut, thank you for your replies. I will first start designing a 12l/hour, 1 kW feed still that should be capable in producing 1 liter of ethanol an hour.

Has any one seen any photos of their still apart from the lopsided one on their website that only shows the bottom two thirds ??

In the discussion on the ADI forum a link was given for a telemetry dashboard. Unfortunately there you can't see the top of the still to.
I wonder how they handle fusel oil, I would expect at least one take off point in the rectifier column.

[dullfig]

when you run a pot still, all the solids stay behind in the boiler, but in a continuous still you are running raw mash down the stripping column, potentially fouling it up. should I run the mash through a filter of sort of filter befoe pouring it down the stripper? what kind of filter would work best? should be easy to clean

[rad14701]

There's something that's starting to disturb me with regard to the volumes being discussed here... Lets remember that these forums, aside from the craft distillers section, are intended for home distillation for personal consumption and as such, whether talking batch mode or continuous distillation, we need to keep overall production in check... Continuous distillation isn't meant to be running 24/7/365... It simply means being able to start collecting spirits quicker than waiting for a boiler full to come up to temperature... Think of it as more instant gratification for those too impatient to sit on their hands and wait... As soon as folks keep talking large volumes it starts raising the eyebrows of more than just me... This is one of the inherent problems of continuous stills - greed... And we know what greed leads to... I can't say that this direction takes me by surprise in the least and I have anticipated it from the beginning of this topic... Lets keep this whole discussion a bit more realistic from a hobby aspect, please...

[dullfig]

absolutely! continuous distillation doesn't mean you have to run the thing 24/7. It just means that it's not a batch process. You can run it for an hour and get your 1l of alcohol and call it a day. No reason to run it continuously. The whole point is that once the still has stabilized, you don't have to fiddle with it, just let it run until you run out of wash.

[badbird]

volumes being discussed here Continuous distillation isn't meant to be running 24/7/365....

Total agree, we need to tone down the numbers. The reality of my continuous stripper test setup is that it only needs to be put together and run for a day every few months or so to supply the low wines base for Gin, Ouso, etc. So admittedly it would be far cheaper and more practical just to do a normal pot stripping run. BUT to me, i have to admit that is fairly is boring.

Going by what is 'publicly accessible' on the web whole continuous stilling subject is one of the last / least explored areas still left for the hardware experimenters and copper hackers out there.

[badbird]

should I run the mash through a filter

dullfig, I have only run sugar washes (wheaty or all bran) through like the stripper so usually rack the beer off the lees and let em clear up a bit but no filtering. Using Scoria for packing so when finished I just rinse it in a bucket of water and leave it out in the garden for a rest, the sun and rain cleans it up.
Actually haven't noticed it getting very messed up anyway

[DAD300]

As badbird said. There is a practical rub here for me also...if it's not continuous, the time you spend calibrating it for a run will be a loss compared to normal stripping run.

[Jacksonbrown]

So the issue I see with continuous cuts is your likely to have heads or tails passing your hearts take off point all the time which would contaminate your hearts fraction.

With something like my attachment could you get away from that?

With this arrangement of columns it could mean the convergent vapour paths will have shed the higher and lower BP nasties before they reach the product take off port.

Maybe a boka on top taking a few drops a second for heads removal and the tails/spent wash going to drain.
Clearly this is not a finished design and I'm not sure how or where the steam would be introduced but does the initial concept have merit?

[Maritimer]

I can't say that this direction takes me by surprise in the least and I have anticipated it from the beginning of this topic... Lets keep this whole discussion a bit more realistic from a hobby aspect, please...

Rad,

The purpose of this thread is to brainstorm, to let thoughts fly so that when when they do come down to earth, they might have captured something worth keeping. Remember the OP, no criticizing or rewarding. We are only thinking, and trying to think as no one has thunk before.

M

[Edwin Croissant]

[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]