Continuous still brainstorming

[Maritimer]

In a recent thread http://homedistiller.org/forum/viewtopi ... 17&t=45423 , dullfig raised the question of removing methanol in a continuous still. The thread got going quite nicely but faded into the usual dreamers vs realists tug-of-war.

I'd like to propose a thread on continous still brainstorming. Here is a quote from http://www.mindtools.com/brainstm.html" onclick="window.open(this.href);return false;" rel="nofollow

Brainstorming combines a relaxed, informal approach to problem solving with lateral thinking. It encourages people to come up with thoughts and ideas that can, at first, seem a bit crazy. Some of these ideas can be crafted into original, creative solutions to a problem, while others can spark even more ideas. This helps to get people unstuck by "jolting" them out of their normal ways of thinking.

Therefore, during brainstorming sessions, people should avoid criticizing or rewarding ideas. You're trying to open up possibilities and break down incorrect assumptions about the problem's limits. Judgment and analysis at this stage stunts idea generation and limit creativity.

Evaluate ideas at the end of the brainstorming session – this is the time to explore solutions further, using conventional approaches.

This reminds me of a funny game that you can play with some friends. With a few drinks it becomes hilarious. All that is required is that everyone in the group agrees with and expands upon anything that comes up.

Anyone wanna play?

M

[heartcut]

To feed a continuous still long enough to stabilize and run it for a while with hobby size ferments you'd need a small still. Tray behavior changes as the column size decreases and there's supposed to be a lower size limit. Guess the question would be how small can you make a plated still and who has the resources to model the process and/or analyze the output at the different trays. The process software I have access to doesn't work accurately when you get below 8" or so, though you could make some corrective curves with enough results from different sizes that were set up as continuous tray stills. I'm not going to do this, but someone sufficently motivated (but without a lab) might put together a small diameter plated column (with product takeoff at each tray) with at least 8 trays and play with temperature and feed rates till you got tails from the one of the bottom trays and heads from the top. I'd love to do it if I was being paid to, but for me, batch stilling makes some fine stuff already.

[Edwin Croissant]

No criticizing or rewarding? The Vulcan way? I'm in

[Maritimer]

In the spirit of brainstorming, let's try some off-the-wall ideas. It's not so easy on-line like this as it is when you are directly with other people, so that you get immediate interaction. The trick is not to reject an idea, but to play with it, even though it seems absurd. I once solved a seemingly impossible problem involving electricity by asking myself how could I use an insulator instead of a conductor, and the answer just popped out.

We are trying to come up with a small continuous still.

So here are some crazy ideas. See if they suggest something. Offer your own crazy ideas.

Put a little fan in the column, or a loudspeaker that pulses or vibrates the vapour.
Establish an electric field along the column.
Put electric band heaters along the column.

M

[flyingdutchman]

Does it need to be for producing finished product or is it simply enough that it takes wash and strips it?
Perhaps it would be useful just to have a continuous stripping still that can handle larger volumes of wash, then we might not need to be so concerned with how good a separation we get with various cogeners.

In that case perhaps for size we could look at the existing Oldershaw type plated columns
http://prismresearchglass.com/borosilic ... ction.html
This is an example of a plated column that is currently available (implying its still useful) down to about a 1" diameter?

PS I am not suggesting you buy or build an Oldershaw its just an example of how small they make plated columns....

[Edwin Croissant]

Condenser.
The major hurdle is the liquid film with its inherently lower heat transfer-rate. There is a NASA report called Promotion of dropwise condensation of ethyl alcohol, methyl alcohol and acetone by polytetrafluoroethylene.

Experimental overall heat-transfer coefficients are presented for the dropwise condensation of ethyl alcohol, methyl alcohol, and acetone on a teflon-coated condensing surface and for filmwise condensation on a bare iron tube. The composite overall heattransfer coefficients during dropwise condensation are approximately 30 percent greater for ethyl alcohol, 45 percent greater for methyl alcohol, and 65 percent for acetone than those during filmwise condensation on the bare iron tube.

Maybe the condenser efficiency can be increased by connecting the condenser to an ultrasound high power transducer to shake the liquid film of. Maybe the condenser capacity can be regulated with the amount of ultrasound power applied.

[rad14701]

A plated column, or multiple columns, is quite possibly the only viable option for a continuous still at the hobby level... The major problem with the other topic, as we've seen several times, is the Charles 803 not being the right theoretical design for our purpose...

Some of the prime considerations for a hobby scale design might be:

• Inexpensive and simple to build
• Some form of ability to make cuts so it is more than merely a stripper
• Perhaps the ability to shut down and restart easily
• The ability to operate without using complex computerized controllers and sensors

A basic continuous still, if it to be truly classified as continuous, needs a method of metering the wash input based on waste output... And it should use steam as heat with the wash metered in part way up the column... Running off a boiler full of heated wash is nothing more than a remote boiler batch mode reflux column...

[Maritimer]

Edwin, thanks for playing the game.

So, a PTFE-covered condenser would probably shed any condensates very easily. And with vibration, nothing would stick to it. There wouldn't be any film-conduction loss. The rules say no criticising or rewarding ideas, so I won't.

Now we have this super-efficient condenser, vibrating like crazy.

Suppose you set up an acoustic standing wave in the space between the reflux condenser and the top of the packing. Maybe there would be some separation of different density vapours.

We need separation by temperature.

What if you put a maser in the column? That's the microwave heater in a microwave oven. Do ethanol and the other vapours behave differently in a waveguide?
----------------------------

Well, heartcut and rad have shown us the dimensions of the box we are trying to get out of. We need to get over the wall to find unknown solutions.

M

[flyingdutchman]

OK I assume we want more than just a continuous stripping still figured I would start with the easiest.
So maybe we could just start with some basic design parameters.
product
Are we shooting for ~95% (my guess is yes)
System Size (See heartcut's notes)
1) What feed rate might we be looking for?
2) What size column or columns (don't forget what happened with the 2 inch plated column builds here)
3) Could we get around the 2 inch plated column problem by having the stripping column plated and the rectifier packed?
Logistics
1) We need to meter the output rate (as Rad already pointed out) preferably a simple way
2) We might want some form of reboiler to be sure the bottoms of the stripping column are exhausted (relatively speaking) of alcohol
3) We need some heat/energy source to drive the system
4) we might want to preheat the wash so that entering the column its close to the correct temp so that less energy is needed to vaporize it

Any of it can be done but if we spell out this stuff first it might make it easier?

[Maritimer]

BTW, I invented a continuous stripping still a while ago: http://homedistiller.org/forum/viewtopi ... continuous . I don't use it because it needs a metering pump, which I don't want to pay for, as I don't drink much any more. One thing not mentioned in the thread is that it would be very easy to adapt to propane. From a 10% Birdwater's wash, it produces 30%ABV distillate.

M

[Edwin Croissant]

What if you put a maser in the column? That's the microwave heater in a microwave oven.

About 6 months ago there was a discussion on the Dutch forum about the effectiveness of agitating the boiler content to prevent smearing in a pot still. Odin asked some commercial distillers if they agitate and received the answer that is was not effective (iirc, if not, my bad). Now that I know that the fusel oils are much more volatile in a low concentration, I think that those commercial distillers are doing a fast stripping run and make their cuts in the low wine run in which the fusel oils are more spread out over the heads and hearts. Agitating would not make a big difference during a low wine run I think.

Now suppose the fusel oils can be compressed by agitating during the first run

In the same period an outside the box thinker called Arjan dropped a small fountain pump in his still filled with some left over washes and brought the content to the boil. He noticed that no bubbles on the bottom of his boiler were formed not even with his burner at full power. With the pump switched off bubbles were formed the size of ping pong balls. With the pump switched on the bubbles in the liquid were really small. With the burner at full power the liquid appeared white. Also the temperature never exceeded 82 degrees. Without the pump the temperature became much higher.

A magnetron heated boiler would heat the boiler content very evenly and would combine both heater and pump. Secondhand magnetrons are cheap and the electronics are very simple and robust. This is not a project for the faint hearted Very high voltage, microwave radiation, risk of blowing yourself up, lethal business But I think it is doable for a bright spark

[Lester]

How about ionizing the vapor with a high voltage potential, then selectively steering the charged vapor molecules using magnets? Think CRT.

Or passing the vapor through an electrostatic field like between the plates of a capacitor?

I have a 7kv power supply waiting to be used......

[Maritimer]

We need a long column, so how about a helix?

Or invisible, massless packing?

A temperature gradient.

The condensate falls from the reflux coil and is inhibited from falling down by a field that pulls it up. Can the alcohol liquids and water liquid be charged? They are insulators, so maybe.

So the liquid gets a charge on the condenser, but is pushed off it from the ultrasonic vibration.

Use a Y-connector on the coolant line to inject ultrasound into the coolant.

The charged droplets, which could be quite small because of the vibration, would be repelled away from the condenser. So how do they keep their charge--they will charge the upcoming vapour. Maybe not--a charged object in the atmosphere doesn't immediately discharge.

Or maybe the droplets could be so small that the upcoming vapour pushes them back up.

So now we have a rainfall of charged liquid.

It falls into the massless packing which is actually an electrical or magnetic field.

A magnetic field. The faster the charged droplet tries to move, the more resistance it will meet--Lenz's Law. Like that experiment where you drop a magnet down an electrically conducting tube, and it falls slowly because it is creating an opposing magnetic field in the tube.

-------------------

The rules say that we step back and look at what we've got. It's too early for that, but I would like to say something about brainstorming. One of the rules is that there is no criticizing or rewarding. That's because we are intentionally coming up with ideas that can't work. The point is to force yourself to get out of the usual course of thinking. It's starting to work.

So don't be afraid, folks, in this case saying something stupid could be the key to a solution.

M

[Lester]

A horn shape (as opposed to a straight tube) would have a natural gradient by virtue of its shape........so how can we exploit this shape to induce the temperature gradient needed for separation of the fractions? vapor velocity would be a function of the cross sectional area.......

[Edwin Croissant]

We need a long column, so how about a helix?

I found this one in Treatise on general and industrial organic chemistry published in 1921 page 162.

Baglioni tried in the same period as Blumenthal a double Archimedian screw in which the liquid flowed downwards and the vapor upwards with poor results as the vapor was forced over the liquid. (from A Short History of the Art of Distillation by R.J. Forbes page 310, no link here, you got to buy this book)

[Maritimer]

My Dear Lord Croissant,

What a wonderful library of distillation books you must have! I can see you in your ancient stone tower, surrounded by your distillation tomes propped on their slanted reading stands as you take notes with an electronic quill.

Lester's idea of a conical column is interesting. Since the area of the column varies as the square of the diameter, even a small difference could be significant. Would this effectively increase the length of the column? Say you have a column that is 3" dia at the bottom and 2" dia before it gets to the take-off and reflux condenser (I always think VM, because neutral is my only desired product). Taking ratios of areas: 3^2/2^2=9/4=2-1/4. The area at the base of the column is 2-1/4 times as large as the top.

As the refluxed liquid falls down, it would fall mainly in the center of the packing. Meanwhile the vapour would be everywhere, maybe coming up easily around the sides--no, the slope would be too gentle...

This is a very interesting idea. Anyone have some thoughts on it?

M

[flyingdutchman]

Perhaps not unlike Dufton's Spiral Column?
http://www.rsc.org/chemistryworld/2012/ ... ral-column

Or even a spiral brush for packing (reported HETP of 2.3 inches, conditions??)
http://pubs.acs.org/doi/abs/10.1021/ed4 ... ode=jceda8

Or even CM warren's Constant temperature distillation head (spiral). It works in a manner different than you might expect.
http://www.scs.illinois.edu/~mainzv/HIS ... 12-117.pdf

Later improved upon by both FD Brown (NOTE it looks amazingly similar to PONU, but functions somewhat differently) http://books.google.com/books?id=erZLAA ... 22&f=false

and S. Young (I wont bother with a link as I have posted his texts repeatedly here) who in his time was considered on of the foremost experts in the field of distillation.

I like all of your ideas.
One thought, for some of these distillation ideas, would be to include a literature reference. That way we can see if it has been attempted and published upon.

[Edwin Croissant]

What a wonderful library of distillation books you must have! I can see you in your ancient stone tower, surrounded by your distillation tomes propped on their slanted reading stands as you take notes with an electronic quill.

Uh, no, the only physical book I have on this subject is A Short History of the Art of Distillation by R.J. Forbes and thats only because I could not locate a digitized copy. So no stone tower I'm afraid. I do like the idea Sounds a lot better then a man's cave.

When I got interested in distillation I couldn't grok the concept of reflux. There was simply to much conflicting information. Some sources stated that you don't need reflux and that by making a column tall enough you can get perfect separation without reflux and that reflux was only necessary to limit the hight of a column to a more practical value. It seems like something magically was going on in the column especially in the bottom end. Based on the amount and concentration of the ethanol coming out from the top I (wrongly) concluded that, as it is impossible that more ethanol leaves the column than the amount that enters the column, the bottom had to receive much more vapor than the top was producing. So I asked myself why are all the columns straight and not made in the shape of a vuvuzela. So I started to look at all the columns and found this wonderful concept of the bubble ball which reinforced the delusion I had.

After a while I came so my senses.

Starting from scratch I concluded from the obvious assumption that no more ethanol could come out as there was put in, the function of the column was to prevent the water from reaching the top of the column. Reflux is a badly chosen name for a process of two partial interwoven cycles. Ethanol is falling as a liquid and water is rising as vapor. When they meet , the water evaporates the ethanol, condenses in the process and falls back to the boiler. The evaporated ethanol rises up to the condenser. So part of the ethanol vapor that is leaving the column is borrowed, and must be returned to complete the cycle. “Ask not what you must leave behind, ask what you can take along” is the proper state of mind to understand this process. The ethanol we can take off is at most the ethanol that is evaporated in our boiler and fed into our column. We cannot turn water into ethanol, but with this trick we can block the water and retrieve the ethanol only.

So I think that you can start with a short wide column, than a condenser to block some of the water, continue with a thinner column, then again a condenser, and a even thinner column, etc. but this would be difficult to make. And that is the problem with all those beautiful different designs of plates:, helix, double helix, bubble caps in a spiral configuration, etc. There are expensive to make. And we now have SPP with a HETP of less then 3 cm. Or lava rock.

[Maritimer]

FlyingDutchman,

I find the citations you give rather flabbergasting. How do you ever find something in an obscure work by Humphrey Davies? Maybe it's not so obscure to the cognoscenti. Maybe you could give us a little lecture on how to find such things.

I looked for "tapered fractional distillation column" in Google Books, Google scholar, and Google web. Not much. Where would you look?

Did Lester mean to have the column small at the base and become larger as it rises?
___________________________________

So let us move from the brainstorming stage to the evaluation stage. We have looked at a lot of off-the-wall ideas.

The perported goal was to devise a small continuous still.

My secret goal was only to get some interesting ideas bouncing around that would take us out of the usual discussions. It's disappointing that so few people are willing to let their imaginations fly. Is it fear of being "wrong," or is it that they don't want to release their ideas (intellectual property) to the public, thereby no longer owning them? Personally, I find holding on to an idea because it is "mine" is an old-fashioned notion. Do you think you will patent your idea and make a fortune? If your idea is really good, you will have to defend yourself against the big corporations. And most ideas that are patented never make a dime. Why not just make a public declaration of your idea? You can show people where it was posted. Of course, a forum like this an be easily manipulated by the folk who run them.

The two ideas that stand out for me are the ultrasonic condenser and the tapered column.

What do you think?

M

[Edwin Croissant]

I think the major problem in continuous distillation is how to feed the beast with a constant flow rate.
Our ancestors kept the pressure drop of a control valve constant. [td][attachment=1]gewicht 2_compressed.jpg[/attachment][/td][td][attachment=0]vlotter 2_compressed.jpg[/attachment][/td] Either by float or by weight.
I have seen the use of a peristaltic pump, this works but is expensive. I probably can stabilize a small DC operated pump with a flow sensor. Flow rate must me around 6 liter an hour for a 500W unit up to 36 liter an hour for a 3000 W unit. Maximum pressure 0.5 bar. So it is not a big pump Are there more ways to do this?

[Lester]

Did Lester mean to have the column small at the base and become larger as it rises?

It was just an idea that came up, not sure if it's been considered before. We were just brainstorming anyway.

[Maritimer]

Hi Edwin,

Keeping the head constant is only part of the problem. I found that the orifice required to maintain such a low flow is so tiny that any particles in the wash could clog it. Rather than a continuous flow, a "ratcheted" flow would do, that is, a few milliliters every so often. Any old ideas on something like that?

M

[Edwin Croissant]

My secret goal was only to get some interesting ideas bouncing around that would take us out of the usual discussions. It's disappointing that so few people are willing to let their imaginations fly.

I think that most people on this forum are very conservative. When my grandfather was young the relative volatility of fusel oil was already known. More then a century has past since and there are still people who outright reject the idea

Is it fear of being "wrong," or is it that they don't want to release their ideas (intellectual property) to the public, thereby no longer owning them? Personally, I find holding on to an idea because it is "mine" is an old-fashioned notion. Do you think you will patent your idea and make a fortune? If your idea is really good, you will have to defend yourself against the big corporations. And most ideas that are patented never make a dime. Why not just make a public declaration of your idea? You can show people where it was posted. Of course, a forum like this an be easily manipulated by the folk who run them.

Today we have patent wars about smart telephones. In the early 1800 there were patent wars about distilling. The good thing is that almost every idea about distilling was patented some time ago and are now in the public domain. As an engineer I think that patents, copyrights etc. are detrimental for progress. However the money chasers are not interested in progress, only the amount of power and money they can acquire. But maybe a real bright idea posted here could be considered prior art.

[Edwin Croissant]

Keeping the head constant is only part of the problem. I found that the orifice required to maintain such a low flow is so tiny that any particles in the wash could clog it. Rather than a continuous flow, a "ratcheted" flow would do, that is, a few milliliters every so often. Any old ideas on something like that?

Something like a bucket chain Archimedes screw That's brainstorming

[heartcut]

peristaltic pumps will do just about any flow rate

[flyingdutchman]

HI

I found that the orifice required to maintain such a low flow is so tiny that any particles in the wash could clog it. Rather than a continuous flow, a "ratcheted" flow would do, that is, a few milliliters every so often. Any old ideas on something like that?

I wonder if the people working with producing biofuels from corn don't have a similar issues with particles causing clogging (both the feed and the plates) and already have a work around we could employ?
Also metering flow rate might be important with regards to required heat input and perhaps even spent wash removal?

ps I was just goofing around researching spiral still heads out of curiosity as they were related to the constant temperature still heads (by Warren and later Brown) and one if the earlier improvements to increase separation of pot still heads.
plus I have unlimited accesss to Scifinder lol

Oh yah ebay...
http://www.ebay.com/bhp/peristaltic-pump thanks Heartcut great idea.

[heartcut]

They also almost never clog as long as the tubing gets replaced occasionally. I take mine everywhere.

[dullfig]

I'm wondering why it seems to be the consensus that the still would have to have trays instead of packing. is there a reason it cannot be made with packing instead of trays?

[dullfig]

oh, and I found this peristaltic pump on ebay for $15:

http://www.ebay.com/itm/6VDC-Dosing-Pum ... 2a362f8466" onclick="window.open(this.href);return false;" rel="nofollow

Not sure if it would have the capacity required.

[dullfig]

hey, with two peristaltic pumps it seems it would be easy to maintain a steady state in the still. If you know the ABV in your wort, and you know how much wort your are feeding into the still, then you would know how much alcohol to remove from the still, right? With a LM still, you would reflux all of the alcohol at the top, and then a peristaltic pump would remove a measured quantity of alcohol. Assuming these $15 pumps work... And I guess you have to make sure your tubing is compatible with alcohol. The dreaded "no plastic in your still" rule.