Please review the continuous still design

[manu de hanoi]

Hi all,

I grow tired of the 3 hours needed to heat the 100 liters. Plus
continous distill saves water (when wash is used for cooling) and energy.

So, because continuous distill can save time, space (no hudge boiler),
energy and water and because it is technically challenging, I'd like
to give it a try.

Based on bokabob's mini (nixon) still and on some drawings from
homedistillers.org and forum (i will post there too but the forum is
offline) I designed something here :


pic:


The unit is the millimeter, the idea here is not to use a pump, but
just siphon power. Beside collecting heat from spent wash, the fresh
wash also goes thru the colling/reflux tubing.

Moreover, I figured that if a U shaped siphon could prevent steam from
escaping at the fesh wash column entry point, the same could be done
for preventing steam from escaping the boiler at the spent wash exit
point. That's why the cooling jacket is u shaped (it also lengthen the
jacket), ...making a U shaped jacked isnt too hard i hope (just bend
the tubes together ?)...

Please share your thoughts....I worry about
- the column entry point vs the temperature of the wash (is it too
low/too cold ?),
- the cooling power of the fresh wash, given that it's flow is quite
small in the cooling head.


Cheers still heads
Manu

--------Rikus answer----------------

I hope you understand that with this type of continuous system you
still need to do a separate rectification run to get rid of heads. If
you want it continuous I do recommend some level of automation. Needle
valves will not hold their calibration in application like this (as
has been shown).

For just a plain stripper you should try Automatic Feed Control (AFC)
as has been discussed here. One of our members built an air-cooled
version that put out some serious amounts (several liters / hour) of
65-85% stuff. If you want it higher you can in theory (haven't had
time to test this) add ARC on top of that and get 95.6% stuff out of
your stripper.

Here's a sketch of AFC-ARC combo that I may build one day time
permitting - I have all the parts, just need to put it together and test.

http://groups.yahoo.com/group/Distiller ... FC-ARC.JPG" onclick="window.open(this.href);return false;" rel="nofollow

The lower part has been tested and it works well.

Cheers, Riku

[stoker]

I like the idea of preheating it like this, but if you want to run your condenser-'water' faster, you also have to raise the feed of new wash to the column, and that's not (always) good.

[absinthe]

I'm not sure if you will get the flow you need in the condenser at the top fast enough with this method..

but you could use a 2 coil system in the top one just plain water and a coil inside or around that one filled with your mash...

the other thing i have found form playing with my new "in line stripping flange" is that you want as constant flow as you can so gravity feed is not the best as it will slow as the head decreases (i found that i needed to keep the head above my little pump pretty much constant to get even flow) you will also want to add some kind of filter if you have the chance of any grain being left in the wash...

also i will be adding a temp prob into the bottom of the tower to know if i am losing and etho to the boiler..

you could have a valve after to inlet airlock and a float valve in a reservoir instead of the funnel to keep the flow and head constant.

[Nykter]

I agree to most of that.
I have tried some continuous setups, but think that they are only useful for stripping in a hobby environment, since it's difficult to get every parameter correctly tuned.

It might be difficult to keep a steady flow of mash with a needle valve, since it might become clogged with yeast and other residue. In a continuous stripper you might want to try AFC, a "system" where the mask is fed through a pipe entering the column in the middle, and using the temperature there for boiling the mash and pump it to the top of the column with the thermosiphon principle. This stops the feed if the temperature decreases, thus controlling the feed and preventing ethanol from reaching the bolier and leave.

Using mash for cooling isn't sufficient, especially if you want reflux.

[absinthe]

well i just joined the yahoo site and it seems that my float idea is almost an AFC lol although you would need to have the float calibrated very precisely to get a good even flow..

i think using it to keep the head constant and regulating the flow with a small valve would be better...

or you could try another idea i was thinking..

use a small pump and a small variac (auto transformer) to change the voltage to the pump and there by the pump speed and flow rate

[Dnderhead]

I'm not into this continuous thing but if you run wash into float chamber
then to still this would keep constant head as wash was used

[rad14701]

I have contemplated a similar design, except using a hot water heater element screwed vertically into the bottom of the column... Granted, such a setup would require that enough wash covers the element, but it sure would speed the overall process as long as you could maintain adequate reflux...

I didn't think about running wash through the condenser and I'm not sure I'd choose that route myself, but if it works that would be great... If I was to choose to do it I might try to chill the wash below the ambient temperature, however... I'm not too sure about the siphoning idea for flow control but, again, if it works - great...

[Nykter]

This is a setup I've tried a couple of times, in various sizes. The pump is submersed in the wash, and running continuously, The wash reservoir (1) has an overflow, returning the excess was to the fermenter, maintaining a steady level of wash in the feed system. Note that the was level is 10 to 40 mm below the end of the AFC pipe, so no wash will flow in a cool still.

Once the water in the boiler is boiling, steam will heat the column to 100C. This will cause the mash int the tube at (2) to boil, and the vapour causing the mash to overflow into the column. If the feed gets too fierce, the temperature at (2) will decrease below the boling point of the wash, stopping the feed. This makes the system self controlling. As Absinthe writes, a thermometer just above the boiler will show if alcohol is leaving the system via the boiler, but a properly designed system would prevent this automatically.

This is an extremely compact stripper, the column, including boiler is just 1.2 to 1.5 , diameter 54 och 65 mm. The boiler doesn't have to be more than the lowest 100-200 mm of the column.

A stripper with 65 mm column and 3000W element can strip somewhere around 10 litres per hour.

One of the drawbacks with AFC might be that it prevents he use of a heat recovery system.

[absinthe]

could you still not run the inlet pipe down to the heat exchanger on the way to the injector and the thermo syphoning effect keep the flow to wards to still end of things? (if you get what i mean)

the only drawback it it might create some real syphoning and cause it to flow faster than it would normally

i hope my explanation makes sense

[rad14701]

Now, if I have my head wrapped around this correctly, Nykter, this setup never actually pumps wash into the bottom of the column, where you would have a bubbler in a standard continuous column like a Charles 803... Instead, you are relying on the steam in the column to pre-heat the mash... Am I correct on this...??? I guess what has me confused is how the heavier fluids end up out of that heated up-tube as it would seem that they would settle in the bottom of the U along with any solids remaining in the mash... Can you clarify this a bit for us please, Nykter...???

[Nykter]

Absinthe, I think you are right in that. The only problem I see with preheating is as you say the possibility of getting a siphon effect out of the preheating. I just haven't thought of trying it. In my setup the wash will be preheated in the bend, stealing heat from the column at this point.

Rad14701, the boiling in the bend isn't complete, so to say, it just pushes the wash to the top of the column, thus rinsing out all sorts of residue into the column. The final evapourisation takes place in the column, when the wash dribbles down through the packing. You'll have to keep in mind that this is just a stripper, not a complete continuous system. The whole column in this system represents the bubbler in a classic continuous still.
As Riku states in the link in the original post, you could add a rectifying column to this setup.

I haven't made any longer runs, only a couple of hour runs, so I can't say for sure, but I haven't had any problems with residues in the bend.

[rad14701]

Thanks for the clarification, Nykter... True, such a column would only be good for stripping runs... Although you wouldn't really need to worry about tails you would always have heads in the output...

[HookLine]

Nice diagrams, Nykter, and Manu.

[Nykter]

True, removing heads is difficult in a continuous setup. Can't be made properly in a single column. You will need a separate one to keep heads from following the product out.

Another problem I forgot to mention is that yeast and other solids stick to the top of the packing, and finally blocks it. I have only tried pot scrubbers as packing, but have heard from another Swede whos into continuous stills that raschig rings and likes withstand this buildup better.

[manu de hanoi]

thanks all for your comments.
1) I believe wash can be used for cooling because basically, with a 10% ABV wash, it will have to cool 10% of it's liquid equivalent volume if you are distilling close to 78 Celsius (got that ?).

2) But mash may not be enough for serious reflux (phlegm is refluxed 7 times for 95% ABV according to Barbet), that`s why I now consider keeping my jacketed cooler instead of making a bokakob/nixton/stone head.

The reflux cooling line will be separated from the cooling line allowing the use of water for reflux cooling (lol).



3)Thanks Nykter for explaining that mysterious AFC

I feel deep inside that a good preheating of the wash is the key to decent performance . And I want 85 ABV. It would be a complete waste of time if just used as a "stripper" (60 abv). That's why I cant use AFC the way it's shown. If i have to turn the valve handle a bit every 10 min then be it


3.1) I am reading and re reading Barbet's distill manual (fairesagnole.eu), especially the rectification chapters. And something ain't clear (paragraph 133), will i get tails or not in the distillate ?. I thought not, cause i intend to run continuously at 78/82 Celcius and because when distilling at these temps on a regular reflux bach setup you're not supposed to get tails, but then Barbet advocates for 2 rectification columns, one for the heads one for the tails (see drawing 34).

3.2) If no tails in the distillate as i hope, I would just either
- heat a batch till the foreheads get out then stop (no need to redistill everything).

- or even better, alike Barbet continuous rectif system, pass the spirit in the continuous still instead of wash with reflux (in order to concentrate the heads), this time , foreheads will be distilled instead of ethanol (which temperature would you predict /recommend ?), and the good alcohol will get out from the boiler where the spent wash used to.

3.3) And if tails ????


@absinthe: the wash trip down to the heat exchanger doesnt change siphon pressure. what is this float chamber thing?

[Dnderhead]

I'm not into these things but your siphon would not work when tank
level gets below out put it will stop If you had tank with adjustable
float overflow to input of still as old kerosene heaters had ?

[Nykter]

OK. So you've really decided to make a reflux continouos system. Cool.


1) That might be correct, the eash might be enough to cool the product only, if you use water to cool the reflux. You will have to take into account that you arent acually boiling the wash in the product condenser, just heating it from 20 C to 90 C (thats about where mash boils), and you are condensing the alcohol, which needs more cooling than just chilling it down a couple of degrees. Do the math and you will see if it works.

2) You should count on a reflux ratio exactly the same way you would on a batch still.

3) The preheating won't make any difference in quality, just energy consumption. And, you shouldn't be satisfied with anything below 95%ABV in any still with a column... The quality measure on these is just the amount of fusils.

3.1) Theoretically you should be able to get rid of tails, but not heads in a single column system. That is, if you manage to fine tune everything and keep it correctly tuned during the whole run. One mistake might need restabilisation of the whole system.
Wish I knew French, that book looks really interresting! I dont get exactly what drawing 34 wants to show. Either.

3.2) I think thats correct.

You could build another system for removing heads, I dont think the same system as stripping and tails removal should be used for this, you would pick ip the impurities in the lower parts of it, and you would also want to build this with properties optimized for heads removal.

3.2) Do as I did, discover that continuous systems are too complicated for home production and revert to batch distilling


Good luck, and please keep us updated with your progress.

/Nykter

[absinthe]

@absinthe: the wash trip down to the heat exchanger doesnt change siphon pressure. what is this float chamber thing?

for an AFC you could do it with a float valve instead of the overflow system that Nykter drew a pic of...

i was referring to the thermo-syphoning effect that would occur with a heat exchanger on an AFC...

another idea i had was to use the overflow system that Nykter describes but with a small reservoir that you top up with mash as shes running.. but pump the mash through the heat exchanger on the way to the overflow chamber.. the mash will take the energy on it way through and slowly heat the bucket up.. thus not waisting energy...

[manu de hanoi]

for an AFC you could do it with a float valve instead of the overflow system that Nykter drew a pic of...

when thinking float valve only 3 examples come to my mind,
1) toilet flush -> too big
2) water tank on the roof -> too big
3) scuba diving / ping pong ball -> might be feasible & the right size....

other than that I wuldnt know where to find a float valve

[Nykter]

Absinthe, the system recirculating through the condenser could work. But once all the mash is close to its boining point it might need cooling. If it does reach this temp.


The toilet flush style system would work. Not an authentic of course it'll be too big, but the principle. You could also take a look at a carburettor.

Water tank on the roof, thats the same principle, isn't it?

Scuba ping pong, would that be a system like those?

You just need to keep in mind that the system is sensitive to the mash level. it cant fluctuate more than a couple of milimetres before the feed goes out of bounds.


I have also tried a level switch switching on and off a pump pumping the mash to a reservoir. This last system with the overflow is a little more elegant and not so space consuming. I like the pump system, since with it I dont need to rig a feeding reservoir above the still, just have to dip a pipe ur a pump into the fermenter. and start.

The beauty of a coutinuous stripper is that you connect everything, fill teh boiler with water, switch it on, and within five minutes product starts flowing.


Manu, an advice for you starting to build a system as complicated as this is start simple, make a stripper without AFC and heat recovery systems, and extend it component by component learning something every time. If you try to build a complete system with heads removal section, you will never know where to fix it when it doesn't work. And it won't work the first tIme, thats for sure!

I'm really happy someone wants to try this and hope you will succeed and tell us how you did it.

[byacey]

I don't want to discourage you, but it seems this kind of setup would require real close babysitting for long periods of time due to some of the critical parameters it must operate under, such as liquid level, flow rate, etc.
A float getting hung up or stuck closed, particulate restricting your wash flow, or any other host of problems could spell disaster.

At least with a reflux column, you can read a book, watch TV or whatever while the still is running through it's cycle with occasional attention, as long as you're nearby. I usually put my feet up and read or listen to the radio.

[Nykter]

Isn't that what you want? I cant help it but I'm always sitting watching my stills running, counting every drop...
Dont' want to miss that, reading or watchin TV.

[Dnderhead]

If helps you guys out they make small floats four fish tanks , hydroponics, and those small front yard ponds but most are plastic

[byacey]

Isn't that what you want? I cant help it but I'm always sitting watching my stills running, counting every drop...
Dont' want to miss that, reading or watchin TV.

This would probably hypnotize a person after watching the dripping for 6 hours straight. I like to sit back , relax and sample previously processed product.

[Nykter]

Yea maybe.
I mostly do smaller runs, more of an experimenter than a producer so to speak. And never just sit there watching, I like to tweak my way through the runs, cant keep my hands of it.
And never sample while distilling.

[Ricky]

i think it was on the mother site where i read about an automatic heads seperator. or maybe the yahoo site. i cant really remember. if you could find it you may be able to apply it to these stills yall are trying to make. i dont know but just a thought.

[Nykter]

No, if it's the one that's been recently published in Riku's book "Designing and building automatic stills" it won't easily fit onto a continuous still.
This heads separator works by collecting all heads during the stabilisation phase, and in a continuous you would add heads continuously, so there will allways be heads in the still, wich can leak out.

You would have to build a heads trap with two columns, one to concentrate heads and one to stop it from exiting the trap. Like this one:
The difficult part is to make a head that distributes the reflux equally between the two column halves.

[manu de hanoi]

i dont get it, how does that work ??

[rad14701]

Ditto what manu de hanoi said... Maybe I'm not translating the illustration properly but it raises more questions than it answers... Can you elaborate, Nykter...???

[Nykter]

Ill try to explain. It's just theoretical havent tried it...
The part of the column thats in the drawing is split into two halves with a wall.
In practice, this is just a way of building a head separating column, but using heat from the first column to heat the second.

The left part of the column is just the top of an ordinary LM column.
The right part is a column that is supposed to stop the heads from leaving the top of the columns. Maybe I should try to draw the equivalent setup built with two pipes. The advantage of this setup is that you dont need to have a separate heating source for the second column.