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Alternative to bubble cap underneath packed column

Alternative to bubble cap underneath packed column

Postby aqua vitae » Tue Jan 29, 2013 9:04 pm

I've already taken this topic up at Artisan aswell as at other forums but not here until now :)
I don't want trouble, I just think it's good to have an open discussion and alternatives as it seems like many new to the hobby thinks a packed column need an expensive bubble cap at the bottom to function properly.

I can't really grasp the theory behind why a bubble cap underneath a packed column would be better than just a longer packed column, lets say scrubbers or mesh as thats well tested by many.
That packed column is better for separation than bubble caps is quite well known.
Not sure about the numbers but it got at least half the HETP, that would mean that in theory the bubble cap could be replaced with half the lenght of packed column.

One of the arguments as to why the bubble cap helps is that it removes much of the water so that the packed column gets to start with a purer ethanol mix. Well, packing is more effient when it comes to separation so that means same lenght of packing would remove even more water, doesnt it?

I also seen arguments that it works like a condenser that allows lighter vapour to pass and removed heavy vapour, but that just feels like re-inventing the labmaster still (with cooling tubes at the bottom of the column), and I thought all agreed that that is a worse design for neutral than a compound still, even when combined as in this case.

One fact is that it is much water in the lower part of the column, wich can form blobs and channels that prevents the vapour/reflux mingeling and leads to worse separation. Centering rings throughout the column helps solving this to a point, but if feed too much power it would probably flood earlier than if it had a bubble cap.
At normal vapour speed as suggested in Compleat Distiller this should not be a problem as the packing is so efficient in separation so the water would just go down the column and into the boiler again, where we want it to be.
But if feeding too much power - very high vapour speed or dense packing this could be a problem... But a bubble cap is expensive to buy and complicated to make and as mentioned above less efficient when it come to separation than packing. So I have a little suggestion about one thing that might work...
Code: Select all
     | |
     | |  <-- 2" column
     |-|  <-- centering ring 1-1,5" opening
    /   \ <-- reducer, 2"-3"
    |   |
    |   |
    |   | <-- 3" column
    |   |
 ___|- -|___   <-- centering ring 2" opening
|           |  <-- boiler
|           |
|           |

The 3 inch column at the bottom can hold more liquid and will also reduce vapour speed at the bottom. The centering rings will introduce turbulence that reduce liquid blobs and channeling. The reducer is available from hardware stores as it's used in normal plumbing. Soldered or sealed with amphora society gaskets, ptfe tape or whatever (dough for the HD members).
The 2" column should be as long as normal. The 3" should in theory not have to be longer than a bubble cap, but it's probably for the better if it's a feet or so.
The packing should not touch the centering rings to prevent from flooding.

What do you think? I'm very open to be critizised if I'm wrong, actually I really wan't you to search for flaws in my idea as that would help me understand this more :obscene-drinkingcheers:

(Another person also suggested that SPP users could test using a little mesh at the bottom, as it is less dense and maybe could hold more liquid than SPP without flooding and maybe lead to more stable conditions, easier to test than my idea anyway)
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Re: Alternative to bubble cap underneath packed column

Postby myles » Tue Jan 29, 2013 9:45 pm

Interesting. The way I look at it is this:

In addition to everything mentioned above, the bubble cap plate (or thumper possibly) is also a reservoir that helps to deal with the column bottoms, instead of just throwing them right back into the boiler.

There is also the issue of the use of an extended stabilisation time to permit transfer of most (if not all) of the volatile components out of the primary boiler before any product is taken. If you go down this route you need somewhere to hold those volatiles in a liquid form under the column.

I am sure you are correct about the packing being better at the separation, I think the issue is the other part - a reservoir of high ABV liquid between the primary boiler and the column.

Could be wrong though. :smile: I hope not as I have deliberately put a thumper under my column with the intention of shifting the entire volatile charge out of the primary before I take any product at all.
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Re: Alternative to bubble cap underneath packed column

Postby aqua vitae » Tue Jan 29, 2013 10:08 pm

The volatile components will be stacked at the top of the column if you let the column stabilize before taking any product out, I don't think you'll hold them in liquid form under the column...
You could go down the route of rikus book and remove high volatiles with the Thorshammer configuration, but I don't think you'll be able to stack high volatiles at the bottom...

About the argument with having something to hold some reflux before just dumping it in the boiler, wouldn't just some extra lenght of packed column do this?
At some point you have to dump water and tail-stuff back in the boiler, and to me it seems better to do it using efficient packing to separate the wanted ethanol rather than in a smeared mix from an inefficient plate. You probably let more ethanol owerflow back in the boiler with a plate than without it...

I can see a point of letting the rising vapour go through waterrich condensate to "collect" flavours for a whiskey, but for neutral it's probably best to simply remove the water with efficient packing and collect the ethanol.

And the wider column tweak at the bottom should take care of the extra liquid so it won't flood if you want to use too much power or very dense packing.
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Re: Alternative to bubble cap underneath packed column

Postby flyingdutchman » Wed Jan 30, 2013 12:01 am

Hi AV,
Interesting question. I am not trying to question what others have observed but sometimes more information can be helpful so with that in mind might I ask...
1) How was it determined that placing a bubble cap beneath the packing was more efficient than adding the equivalent of 1 plates worth of packing .
note: Just trying to confirm that all other variables (like column size and shape) were held constant when the plate was added.
2) How much more efficient was it?
3) Is the same effect observed with
a) perforated plate
b) a thumper

Beyond that I have to agree with Myles. If the bubble plate is known to be less efficient than packing it should be some other effect. What I wonder is does a bubble plate hold a greater volume of liquid than 1 EQ of packing. If so is the plate more efficient at preventing liquid (plus might prevent weeping down inner sides) from returning to the boiler. So long as that liquid was of a higher ABV than the boiler charge then I would think that has to be a good thing. Then if we consider what Mike Nixon said in his paper about the benefits of returning reflux to the bottom of the column (but not boiler) it would be of added benefit (thats why I ask about sieve plates and thumpers)
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Re: Alternative to bubble cap underneath packed column

Postby Prairiepiss » Wed Jan 30, 2013 1:51 am

Welcome aboard MD flyingdutchman. Haven't seen you around the forums in a while.

A similar question came up on HD the other day. And an answer influenced by your postings was given. But I never got a good answer to my question about the response. The answer given was basically. Placing a plate under packing is less efficient.

My question is what is the definition of efficient when used in this statement?

So maybe you can answer my question. What defines the efficiency of a still? I'm talking whole still. Not an individual piece of that still. Is it degree of separation? The ability to increase ABV? The speed at which it can produce a given product? Maybe even ability to manage temps better (stability)? Or is it a combination of all the above? If so what percentages of each influence the determination?

I'm just trying to understand what others seem to think efficiencys are. Because there are still many out here that seem as though they have a different definition of what a still should be graded on for efficiency.
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Re: Alternative to bubble cap underneath packed column

Postby hard times » Wed Jan 30, 2013 2:01 am

I'm having the same thoughts.
Is there a way to test how much enrichment of alc vapor
or removal of water is accurring with the ball by itself.

Is it possible that it is just limiting the ability to overdrive
the column by flooding the ball and can be seen thru
the window and corrected.
What ever it does it appears to quicken takeoff rates and increase
alc levels.


I don't deny it works, I just can't figure how it works so I can figure
the proper size/combination to work with my 2in column.

I was writing this out as PP was posting his questions, looks like
we are having smiliar thoughts
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Re: Alternative to bubble cap underneath packed column

Postby flyingdutchman » Wed Jan 30, 2013 3:33 am

Hi PP,
Good to see you and thanks for the welcome. I have to admit that's a good question about efficiency. I can give you my best interpretation but if some one has a better answer please step in to correct me.

One way to look at is what I could call overall system efficiency which would be how much ethanol is in the wash vs how much ethanol is collected. As an example lets say we got azeotope but only collected 10th and everything else was lost somehow..... but that's probably not what we are looking for here.

I think the function of a distillation column is to perform a separation of liquid components (based on their physical properties). To me this has two measurable features..
1) Number of plates (So i tend to think more plates ~ a higher ABV)
2) The actual resolution, the ability to separate two peaks (like two or more volatile components with close boiling points). Poor resolution is kind of like smearing where two separable components coelute instead of being separated. Maybe an image will help here (lets say peak 1 is ethanol and peak 2 is ethyl acetate).
resolution.jpg

So maybe even though we get a good separation of water/ethanol we could get poor resolution between other components. We should be able to calculate the number of plates based on wash ABV and distillate ABV. I suspect we can taste poor resolution but to quantify that might take a little more work (or better instruments).

In the end I think the easiest answer for me but not truly complete is our overall plate efficiency which is the ratio of the number of physical plates to calculated plates from a run based on wash ABV vs distillate ABV . Or for packing how many theoretical plates we should have for the given height some specific packing vs how many we calculate based on wash ABV vs distillate ABV . I am betting that what my post was about on HD from http://en.wikipedia.org/wiki/Theoretical_plate
so say we had a result where the column gave the equivilent of 8 plates (measured separation) but we effectively had 10 plates installed (9+1 dephlegmator) I personally would say it had an plate efficiency of 80% efficient based on that

Haha I was writing this as Punkin was posting. In no way is this meant to contradict Punkins above statement its just me rambling (LOL).
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Re: Alternative to bubble cap underneath packed column

Postby myles » Wed Jan 30, 2013 4:22 am

aqua vitae wrote:The volatile components will be stacked at the top of the column if you let the column stabilize before taking any product out, I don't think you'll hold them in liquid form under the column...


Hmm! Well my issue with this is that the column only has sufficient volume to hold a portion of the volatiles in the wash. I want to shift as much of the volatiles as possible out of the wash before I start to separate them. It is not sensible to directly heat a high ABV boiler charge, but the column works better if you can use a higher ABV charge. Using a parasitic boiler between the primary and the column is 1 way to achieve this.

aqua vitae wrote:At some point you have to dump water and tail-stuff back in the boiler


Actually you don't. Provided your column bottoms are depleted of volatiles there is actually no reason to return them to the boiler at all. The reason most folks do so is because their columns are NOT sufficiently effective to remove the volatiles. Usually because they are too short. Take that same column and give it a higher ABV vapour going in - and "tadah" it does a better job. Now the column bottoms might actually be volatile depleted. If they are why would you wish to return them to the boiler? Diluting the boiler charge even further just does not make sense.

aqua vitae wrote:I can see a point of letting the rising vapour go through water rich condensate to "collect" flavours for a whiskey, but for neutral it's probably best to simply remove the water with efficient packing and collect the ethanol.


Possibly but not really interested - I would use a pot still for that. :smile:
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Re: Alternative to bubble cap underneath packed column

Postby Prairiepiss » Wed Jan 30, 2013 8:12 am

AV in order to replicate what is happening by adding a bubble plate to a packed column. You will need replicate what is happening within the bubble plate. With some other equipment. If it was to be done with packing. You would need a section of packing that was to be flooded during operation. Because what is going on has more to do with the amount of liquid then the amount of vapors. And the greater the amount of liquid. The better it seams to work. Not real sure how you could get the same outcome with vapors only.

The reason I ask about efficiency is. Many have a hickup that they tend to look at the efficiencys of the plated sections and the packed sections separately. When they are used together. But they can't be viewed like this. They need to be viewed as a whole. And graded as such.

I consider a hybrid to be amazingly efficient. Only from my own findings. If I can replace 12" of packed column in my still with a 12" section with one plate. And get a much better product at 2 to 3 times the speed. And making the column more stable then before. I would consider that a great increased amount of efficiency.
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Re: Alternative to bubble cap underneath packed column

Postby Prairiepiss » Wed Jan 30, 2013 8:45 am

AV do you do stripping runs before a spirit run in a packed column? If you do why do you do it? Can you replicate a stripping run with a packed section added to a packed column?


The way I look at it is you first need to set goals for the still to meet.
ABV out.
Flavor out.
Speed of take off.
Number of times needed to run.
Amount to recover.
Amount of separation of fractions.

When you have those goals set. Then work on what it will take to achieving those goals with the medium you want to work with.

Like my goals with my still was to increase takeoff speed to at least twice of what I was getting.
To get at least 95% ABV out with one run.
Get better separation or compression of fractions.
And do it all with the least amount of stuff.

I knew going in that more then likely my first trials with a small amount of packing. I probably wouldn't achieve those goals. I figured I would have to add more packing. And or plates.

I was pleasantly surprised to find I achieved all those goals and exceeded some of them. With the minimum amount of packing I was going to test. Now I have to up my goals. To improve it even more.

I feel like I'm just blabing here. Like I do a lot. I guess what I'm asking is. What are your hard goals. That you wish to achieving with this still?

I apologize I'm home sick on meds. And maybe a little loopy. :puke-front:
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Re: Alternative to bubble cap underneath packed column

Postby aqua vitae » Wed Jan 30, 2013 9:20 am

Thank you myles and others for your answers, its good for me to have to question my "truths" :obscene-drinkingcheers:
And I'm sorry if I sound blunt or harsh, my english is limited.

aqua vitae wrote:The volatile components will be stacked at the top of the column if you let the column stabilize before taking any product out, I don't think you'll hold them in liquid form under the column...

myles wrote:Hmm! Well my issue with this is that the column only has sufficient volume to hold a portion of the volatiles in the wash. I want to shift as much of the volatiles as possible out of the wash before I start to separate them. It is not sensible to directly heat a high ABV boiler charge, but the column works better if you can use a higher ABV charge. Using a parasitic boiler between the primary and the column is 1 way to achieve this.


The heads components from a 6 kg sugarwash is actually only 2 dl in liquid volyme if highly concentrated, but in case of a VM there will be no such pools so it have to be concentrated in vapour form, which use much more space. Since we talk about "normal" compound still without Thorshammer you will have to bleed the heads out slowly at a high reflux ratio to keep them concentrated. This means that you always get a buffer zone of heads vapour at the top of the still, if you bleed really slow you can make that zone go almost all the way down.
The point is that the heads will always stack at the top at high reflux and slow bleeding, not at the bottom.
High efficient packing means that the heads buffer zone can go lower at the same reflux ratio than less efficient packing/plates... A hight efficient packing will charge the rest of the column with high ABV, just as a plate does, only more efficient.


aqua vitae wrote:At some point you have to dump water and tail-stuff back in the boiler

myles wrote:Actually you don't. Provided your column bottoms are depleted of volatiles there is actually no reason to return them to the boiler at all. The reason most folks do so is because their columns are NOT sufficiently effective to remove the volatiles. Usually because they are too short. Take that same column and give it a higher ABV vapour going in - and "tadah" it does a better job. Now the column bottoms might actually be volatile depleted. If they are why would you wish to return them to the boiler? Diluting the boiler charge even further just does not make sense.

Yes you do. You only collect heads and ethanol, the water and tails will have to be returned to the boiler. If you don't return the water to the boiler it would be completely empty and dry when the run is finished and this is not the case. There is no way you can make ONLY ethanol and heads vapourize from the boiler, the first stage of distillation will always contain a mixture of what is in the boiler, including water and tails and that have to go back to the boiler.
To me this seems better to do it using efficient packing to separate the wanted ethanol rather than in a smeared mix from an inefficient plate. Possibly as in the sketch in my first post which might solve the other issues mentioned in my first posts.
A too short column lengthened with a bubble plate equals a short column lenghened with more packing, only less efficient. The lower part of the packing removes water and tails and feed the upper part of the packing with higher ABV, just as a plate removes some water and tails and feed the upper part of the column with higher ABV. My point is that both does exactly the same job, BUT, packed column is more efficient than plated column.

The liquid that the bubble plate holds should even be lower in ABV than the rising vapour from the boiler. Sounds contradictive at first, but think of all the water and tails that are being separated by the packed column above the boiler, that has to go somewhere. Preferably down and not up to the outtake.
If it just where packing it would go down in drops and eventually fall back in the boiler, (and re-evaporate together with the wanted ethanol, if any is left in the boiler)
If there is a bubble plate there it will mix with the other liquid and pool there until it overflows back in the boiler, maybe together with some ethanol that did'nt re-evaporate in time (to reach the packing).




aqua vitae wrote:I can see a point of letting the rising vapour go through water rich condensate to "collect" flavours for a whiskey, but for neutral it's probably best to simply remove the water with efficient packing and collect the ethanol.

myles wrote:Possibly but not really interested - I would use a pot still for that. :smile:


Ehrm I totaly agree with you, based on all plate still distilled and pot still distilled whisky I ever drank (commercial products) I chose the pot stilled every day, but that debate is for another day ;)




On efficiency in packing/plates, it probably could be measured using predetermined values in an equation.. The material/construction which can achieve azeotrope ethanol (AE) at a set column lenght (L) and set boiler power (L) from a set boiler strenght and volume (BSV) with the minimum reflux ratio (RR) at the shortest time (T).

Let as many of these values be predetermined and set and measure the rest.. I will try to explain what I mean with some examples...

Ex 1, using E-ARC
In this example the boiler is filled with 25 litre of 14 % mash, BSV is set.
Column lenght is 1 metre, then L is set.
Boiler power is 1,5 kW excluding heat losses, P is set.
Minimum reflux-ratio to achieve azeotrope ethanol is always used in an E-ARC, so minimum RR is set.
A working E-ARC will only give out azeotrope ethanol, then AE is set.
Now measure time and you get the packing efficiency in T unit.

Ex 2. using CM, ambient cooling with convector pipes as dephlag, and some product condenser that is sufficient.
In this example the boiler is filled with 25 litre of 14 % mash, BSV is set.
Column lenght is 1 metre, then L is set.
Boiler power is 1,5 kW excluding heat losses, P is set.
Time is say two hours from the first drip comes out, T is set.
Now there is no way to know what the minimum RR to achieve AE is, but the RR is kind of constant between runs so collect product using the set values described above and measure the ABV, the packings efficiency is now measured in how high ABV it can produce.
This is less reliable than Ex 1 because if the column is too long and the power is low maybe all packings will produce azeotrope ethanol... But if you make sure you are below that it should give out some data.

This is the two I can come up with but you could probably let other values be set and for example measure how long column you need to get certain results etc...

EDIT, I started to write and answer but had to leave the computer for some hours, when I finished other had already posted, my answer to them will soon come in another post :smile:
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Re: Alternative to bubble cap underneath packed column

Postby lokibrew » Wed Jan 30, 2013 9:44 am

Your English is plenty good for around here, and frankly, better than some native speakers. Where are you from?

At the risk of sounding simple.. why don't you try a torpedo, or fab up a thumper before you column and check it out for yourself.. You'd have no problem finding someone to take a torpedo off your hands..

From the looks of Smaug's/Larry's mega thumper setup, i doubt he returns anything to the boiler.

Had a saying when I was studying theory:

"The difference between theory and practice? In theory they are the same.. In practice, they are not"


I can guess that you can run faster because a bubble plate is intended to be flooded, whereas a column loses efficiency when flooded, so it's apples and oranges.

I'm building a modular still and when she's done, I'll likely run plenty of experiments in different configurations, just to see how they work.
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Re: Alternative to bubble cap underneath packed column

Postby aqua vitae » Wed Jan 30, 2013 10:18 am

Prairiepiss wrote:AV in order to replicate what is happening by adding a bubble plate to a packed column. You will need replicate what is happening within the bubble plate. With some other equipment. If it was to be done with packing. You would need a section of packing that was to be flooded during operation. Because what is going on has more to do with the amount of liquid then the amount of vapors. And the greater the amount of liquid. The better it seams to work. Not real sure how you could get the same outcome with vapors only.

No actually not, the bubble plate and the packing achieves the same thing, to over-simplify it; make the water and tailsy stuff go down, and make the ethanol go up.
You don't want the packing to be flooded (my sketch in the first post was a suggestion to try and avoid this if the packing is to dense for the power fed to the boiler), but you want reflux to go down and mingle with the vapour moving up, to create more reflux and enrich the vapour thats moving up, so it's not vapours only either.

Answers in red
Prairiepiss wrote:AV do you do stripping runs before a spirit run in a packed column? If you do why do you do it?
Yes, low wines are easier to store and I do pH adjustements to minimize amount of heads, low wines from two washes are then distilled in one spirit run as boiler only hold one wash, or two washes if stripped into low wines. So it's hard to compare.
Can you replicate a stripping run with a packed section added to a packed column?
In my case no, but I could not replicate it with a bubble plate added below my packed column either


The way I look at it is you first need to set goals for the still to meet.
ABV out. Azeotrope ethanol
Flavor out. None, aka neutral
Speed of take off. As fast as possible
Number of times needed to run. Well, preferable one, but I don't have and E-ARC so I have to run slower and then the wash scorches a little and give a hint of burnt sugar taste, also without the pH adjustments I would loose a tiny bit of ethanol as the heads tainted portion become a little bit bigger.
Amount to recover. As much as possible
Amount of separation of fractions. Don't really understand this, but I want the heads to be compressed as much as possible, and I don't want tails to reach the outtake

When you have those goals set. Then work on what it will take to achieving those goals with the medium you want to work with.

Like my goals with my still was to increase takeoff speed to at least twice of what I was getting.
To get at least 95% ABV out with one run.
Get better separation or compression of fractions.
And do it all with the least amount of stuff.

I knew going in that more then likely my first trials with a small amount of packing. I probably wouldn't achieve those goals. I figured I would have to add more packing. And or plates.

I was pleasantly surprised to find I achieved all those goals and exceeded some of them. With the minimum amount of packing I was going to test. Now I have to up my goals. To improve it even more.

I feel like I'm just blabing here. Like I do a lot. I guess what I'm asking is. What are your hard goals. That you wish to achieving with this still?

I apologize I'm home sick on meds. And maybe a little loopy. :puke-front:


I think it's good that it's not only me blabing :obscene-drinkingcheers:


minime wrote:
myles wrote:
aqua vitae wrote:At some point you have to dump water and tail-stuff back in the boiler

Take that same column and give it a higher ABV vapour going in - and "tadah" it does a better job.


My photo shows that plate operating at 77.4C
Not exactly water boiling there is it?

According to the Boiling Point & Alcohol Strenght table in Designing & Building Automatic Stills you are off the charts, it only shows up to 96,9% and that equals a boiling point at 78.0C (lower boiling point equals higher strenght). So maybe the thermometer is wrong or you got one hell of a still ;-)
What I ment was that the water and tailsy stuff that are separated in the packing above the plate will have to go down and back to the boiler again, no matter if it will have to take the route through the liquid bath on a plate or through that of a packing. And refluxing is more efficient in packing than in plated columns.

lokibrew wrote:Your English is plenty good for around here, and frankly, better than some native speakers. Where are you from?
Thank you :smile: I am from Sweden.
lokibrew wrote:At the risk of sounding simple.. why don't you try a torpedo, or fab up a thumper before you column and check it out for yourself.. You'd have no problem finding someone to take a torpedo off your hands..

From the looks of Smaug's/Larry's mega thumper setup, i doubt he returns anything to the boiler. I bet he does, or else his boiler would run dry at the end of the run.

Had a saying when I was studying theory:

"The difference between theory and practice? In theory they are the same.. In practice, they are not"

That would indeed be the simpliest way, but since I'm from Sweden shipping will cost much, aswell as the torpedo (or whatever bubble plate), and I'm a cheapskate/kind of poor.

Also I does not have a E-ARC, and the only way to really know for sure is to test it as in my example 1... Hopefully someone with an E-ARC will try this and measure time some day so we get hard data, because you are right about your saying about theory :oops:

lokibrew wrote:I can guess that you can run faster because a bubble plate is intended to be flooded, whereas a column loses efficiency when flooded, so it's apples and oranges.

I'm building a modular still and when she's done, I'll likely run plenty of experiments in different configurations, just to see how they work.

Yes, you probably could run faster with a bubble plate underneath a packed column, hence the sketch in my first post with a cheaper solution to the same "problem", a wider column at the bottom to take care of the liquid richer enviroment there Image
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Re: Alternative to bubble cap underneath packed column

Postby Prairiepiss » Wed Jan 30, 2013 10:44 am

Can you replicate a stripping run with a packed section added to a packed column?

In my case no, but I could not replicate it with a bubble plate added below my packed column either

This is where our thoughts defer.

The plated section can provide the same thing a regular stripping run can. Actually more. Or I wouldn't get the results I do.

If I would build a VM head to put on my plated section. I know my results would be much better as far as a true neutral. Much like mini's setup.

But I don't think adding a packed 3" section where my bubble plate section is. Will give me the same results. I would more then likely be back to near the same as I started with. With a slight increase in takeoff speed. But still struggle to get above 95%.

And no larry's inline thumper doesn't return much if any to the boiler. He designed it to not do that. And only provided the ability too in case it was needed.

But really all I can say is if you think it will work. Give it a go. Let us know the outcome. We could discuss what we think mite happen all day long. But without hard evidence. We are all just talking theorys.
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Re: Alternative to bubble cap underneath packed column

Postby aqua vitae » Wed Jan 30, 2013 11:25 am

flyingdutchman wrote:Beyond that I have to agree with Myles. If the bubble plate is known to be less efficient than packing it should be some other effect. What I wonder is does a bubble plate hold a greater volume of liquid than 1 EQ of packing. If so is the plate more efficient at preventing liquid (plus might prevent weeping down inner sides) from returning to the boiler. So long as that liquid was of a higher ABV than the boiler charge then I would think that has to be a good thing. Then if we consider what Mike Nixon said in his paper about the benefits of returning reflux to the bottom of the column (but not boiler) it would be of added benefit (thats why I ask about sieve plates and thumpers)

hard times wrote:I'm having the same thoughts.
Is there a way to test how much enrichment of alc vapor
or removal of water is accurring with the ball by itself.

Is it possible that it is just limiting the ability to overdrive
the column by flooding the ball and can be seen thru
the window and corrected.
What ever it does it appears to quicken takeoff rates and increase
alc levels.


I don't deny it works, I just can't figure how it works so I can figure
the proper size/combination to work with my 2in column.


Missed to answer on these posts, this is in line with my thoughts. Or to be fair, it was stilton that pointed me in this direction in another discussion.

The plate can be fed with higher vapour speeds and more falling reflux than packed column before it floods, and become unstable. A very dense packing as SPP might flood even earlier than a mesh packed column, because there is less area for rising vapour to meet with the liquid-rich enviroment in the bottom of the column, that means higher vapour speed and finally at some point flooding.

A bubble plate obviously works to take care of this issue for this, but is complicated to build and expensive to buy,
That is why I suggested to use a wider column at the bottom to be able to cope with the liquid-richer enviroment, without speeding up the vapour speed too much so it floods. It would probably also be beneficial to use centering rings (maybe as in my sketch) to spash the reflux blobs and further enhance separation.

minime wrote:
aqua vitae wrote:Also I does not have a E-ARC, and the only way to really know for sure is to test it as in my example 1... Hopefully someone with an E-ARC will try this and measure time some day so we get hard data, because you are right about your saying about theory :oops:

Your countryman Crystal Skull has the same bubble plate I use.........Wonder how far he is from Rkr :?:

ImageImageImage

Well, no evidence comes out of discussion whatsoever, but the question was raised and maybe it opens the eyes on some that take manufacturers advice as the only truth. :smile:
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Re: Alternative to bubble cap underneath packed column

Postby myles » Wed Jan 30, 2013 12:00 pm

I am not talking about transferring just the heads aqua vitae, and I am not totally convinced the boiler would run dry.

Hypothetical numbers for a thumper between the boiler and column:

Boiler charged with 40 litres @ 30%. Can be expected to transfer 20 litres @ 60% into the thumper, leaving 20 litres of spent wash behind in the boiler.

That 20 litres @ 60% should produce 12.6 litres @ 95% leaving 7.4 litres behind in the thumper (column bottoms)

Now the question is this - can that 20 litres spent wash in the boiler last long enough to heat the 60% thumper charge until all the hearts have been taken? I don't have the number to hand for the energy required to heat a 60% charge by steam injection.
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Re: Alternative to bubble cap underneath packed column

Postby Kapea » Wed Jan 30, 2013 3:09 pm

So, I've been staring in the SD store window dreaming. What I've come up with is - coming out of my sanke keg boiler triclamp - 2" to 4" reducer - triclamp to 4"x4"x3" T with bubble plate and fancy brass SGK - triclamp to - 2" to 4" reducer - triclamp to my 1250mm VM column. Kinda like a T-shaped bubbleball.

1) Will this configuration be strong enough to support my long-ass VM column?
2) How much taller will my long-ass column be?
3) Aside from being able to see into the base of my column, what benefits can I expect from this configuration?
4) When will the FL office have these parts available again to poor schmoes like me?
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Re: Alternative to bubble cap underneath packed column

Postby Kapea » Wed Jan 30, 2013 3:23 pm

punkin wrote:If you use the Torpedo half you get an extra window too :obscene-drinkingcheers:
NeedToUseSomeImaginationWithThisStuffPunkin


DOH! Exxxxxxcelent!
Not too much of an upgrade in price. Put the bubble plate on the top of the T and have a window into the boiler and a window onto the plate too. Too cool for school amigo. I like it!

Why do the downcomers occupy an offset hole instead of the center hole?
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Re: Alternative to bubble cap underneath packed column

Postby FullySilenced » Wed Jan 30, 2013 4:54 pm

Or use the tee and the torpedo and two plates.... daaa if you got the torpedo use it... to may ways to skin that cat....with the SD Still erector set.... :obscene-drinkingcheers:
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Re: Alternative to bubble cap underneath packed column

Postby Kapea » Wed Jan 30, 2013 6:40 pm

I have a union in the middle of my packed column. I could reduce the packed portion of my column by half, mount it on a two plate - bubble T/torpedo combination, and have a three-window front seat while stillin' some of that elusive silver rum that minime is always talking about.

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Re: Alternative to bubble cap underneath packed column

Postby FullySilenced » Wed Jan 30, 2013 7:38 pm

Now thats a great plan....
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Re: Alternative to bubble cap underneath packed column

Postby Prairiepiss » Wed Jan 30, 2013 9:18 pm

AV the way I see your drawing working is you mite get an increase of takeoff rate. Up to what a 3" packed column is capable of. If you were to use 4" then it would be closer to the take off speed of a 4" packed column. So why not just go with a full 3" or 4" packed column?
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Re: Alternative to bubble cap underneath packed column

Postby rkr » Wed Jan 30, 2013 9:57 pm

minime wrote:
aqua vitae wrote:Also I does not have a E-ARC, and the only way to really know for sure is to test it as in my example 1... Hopefully someone with an E-ARC will try this and measure time some day so we get hard data, because you are right about your saying about theory :oops:

Your countryman Crystal Skull has the same bubble plate I use.........Wonder how far he is from Rkr :?:

BTW, I'm 200 meters above sea that accounts for some error in the temp probe.


Minime, do you have a link to your plate design? Can it be built inside a 54mm column section or 54mm capillary joint? If so I might give it a go, I need to make some neutral stuff shortly so I could do two timed batches. One with the plate and one without, that should give us an answer whether the plate is worth it or not.

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Re: Alternative to bubble cap underneath packed column

Postby aqua vitae » Wed Jan 30, 2013 11:21 pm

Ah well it's not true that it would run entirely dry, kind of in the same way a pot still doesn't run dry. That was an unneccessary exhageration to try and explain the principle... :oops:
But if you think of a pot still run, you run it until there is no more ethanol left in the boiler with pretty much no reflux. You will also remove some water from the boiler as there is no reflux to separate it.
Lets say you run the same amount of mash with the same power setting in a column still. Since you reflux it to get neutral the run takes longer time, but the boiler evapourate pretty much the same amount of vapour constantly, so if no water is ever returned to the boiler it should have even less draff in the boiler after the run than in the pot still mode when the run is done, but it doesnt.
Actually you will have more water left it the boiler after the run in reflux mode then in potstill mode, as the reflux separate water from the vapour and return it to the boiler, via the plate or just through the packing.

I don't understand you example fully, is it some kind of a closed system with steam heating?

minime wrote:
aqua vitae wrote:
Code: Select all
     | |
     | |  <-- 2" column
     |-|  <-- centering ring 1-1,5" opening
    /   \ <-- reducer(s), 2" to 4"
    |   |
    |   |
    |   | <-- 4" column, 7" long
    |   |
 ___|- -|___   <-- centering ring 2-3" opening
|           |  <-- boiler
|           |
|           |

Edited the sketch


OK, looking at this fairly. I am using a 4" bubble cap plate that is 7" in height so a fair comparison to see if I can extract the same benefit should be a 4" packed section no longer than 7". Without moving the temperature probes I should be able to replicate the same temperature profile throughout the run.

Would that be a fair comparison?

Sounds like a fair comparison to me. But I think performance comparisons are more important than just temperature readings, also cool reflux might disturb the readings and measuring in the liquid at the plate might not be comparable with measuring in the vapour below a centering ring :think:
For example how much power it can take before it floods, and try to see if there is any difference how fast you can collect azeotrope between the two etc...

Prairiepiss wrote:AV the way I see your drawing working is you mite get an increase of takeoff rate. Up to what a 3" packed column is capable of. If you were to use 4" then it would be closer to the take off speed of a 4" packed column. So why not just go with a full 3" or 4" packed column?

The speed of wich you can collect azeotrope ethanol does not increase linear with increased column width when using the same boiling power, also my theoretical comparisons was to find an alternative to the bubble plate beneath 2" packed columns, or to find out if it's needed at all.

rkr wrote:Minime, do you have a link to your plate design? Can it be built inside a 54mm column section or 54mm capillary joint? If so I might give it a go, I need to make some neutral stuff shortly so I could do two timed batches. One with the plate and one without, that should give us an answer whether the plate is worth it or not.

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Re: Alternative to bubble cap underneath packed column

Postby Kapea » Thu Jan 31, 2013 12:07 am

Volume in the column does not increase linearly with the increase in column width, it increases exponetially. The area formula is pi times the square of the radius of the column. Volume equals area times length.
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Re: Alternative to bubble cap underneath packed column

Postby rkr » Thu Jan 31, 2013 2:26 am

minime wrote:
rkr wrote:Minime, do you have a link to your plate design? Can it be built inside a 54mm column section or 54mm capillary joint? If so I might give it a go, I need to make some neutral stuff shortly so I could do two timed batches. One with the plate and one without, that should give us an answer whether the plate is worth it or not.

Slainte, Riku

It's a 100mm wet plate with 5 bubble caps and a down comer. I have extended the down comer to increase plate depth to 45mm
Image
Image


That's too big for a quickie test setup. What do you reckon, would a single bubble cap inside a 54mm column piece do the trick with 45mm liquid level? At least it might give us an idea whether it's the amount of liquid in the plate or the plate action itself that counts. That would be relatively easy to manufacture and test. Any ideas how much liquid that plate of your's holds? How much liquid covering the bottom of the downcomer pipe?

Hmm, actually I think the correct question is how much liquid do you have on top of the ventilation holes of those caps? That + a bit extra should be the "vapor lock" liquid level needed for the downcomer.

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Re: Alternative to bubble cap underneath packed column

Postby Prairiepiss » Thu Jan 31, 2013 4:16 am

The deeper the liquid bed. The less flavor will carry over. Making it easier to get a better neutral. While a shallower liquid bed will increase the flavor carry over. You probably won't ever see a difference on a good sized packed column still that already produces a good neutral. Where on my setup I see a big difference between 1" deep and 3" deep. This also holds true for ABV and stability.

But there is the thought that holding as much above the boiler. So it doesn't return. Is the best method. Which also can explain my findings. And I still beleave to be true.

But any amount of liquid on a plate below a packed column. Will increase all of these things. How much hasn't really been determined. Not enough research has been done.

This hybrid setup still deserves a lot more testing and experimenting. So maybe an optimum setup can be found. My research and testing is geared towards finding the best setup for a 2" packed column. Starting with a minimal amount of packing. Unfortunately I only have so much time and limited resources. So any help from any others would be greatly appreciated.
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Re: Alternative to bubble cap underneath packed column

Postby DrWho » Thu Jan 31, 2013 9:04 am

This is a great thread :handgestures-thumbupright: Ever since reading about mini's and PP's success, I've been thinking about building a bubble plate to put under the LM/VM column. Main reason is to make the run quicker. Plus, if I make 3 or so of them I can build a plated column for flavored results (no column, just plates).

From reading through this thread, minime's plate holds about 350 ml of liquid. Quite a bit. With PP's set up holding even more as the depth of liquid is greater. I'm not sure that could be held with a packed section of 100mm (4") column diameter of 180mm (7") in length. And, would a packed section of that dimension be equivalent to one plate?

If it is, and can hold that volume of liquid, then it should act the same as the bubbler.

One thing for sure is that the first two plates create the biggest boost in ABV. Take a low wines run about half way through. With 15% ABV in the boiler the vapor coming off will be about 63%. Then after the bubbler, the vapor will be about 82% ABV. That is a 30% boost in ABV ( 63 + 63 * .30 = 81.9 ABV).

Along with the depth of the liquid stripping flavor, one can take off what is being driven up the column at a higher rate.

:clap:

???
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Re: Alternative to bubble cap underneath packed column

Postby flyingdutchman » Sun Feb 03, 2013 3:32 am

Hi DrWho,
I know of atleast 1 on line calculator to estimate the HETP for different packing materials. It has user defined variables for stuff like RR, power input, column diameter etc. I do not know the rules for posting links to other sites here but a quick google search for
Calculate HETP of still
should get you there.
Its an estimate but it should give you a rough idea.
As far as how much liquid the packing would hold...
1) I think the Compleat Distiller (Nixon and McCaw) does some calculations for the surface area of metal pot scrubbers. Multiply that by the volume you will use and the thickness of the water layer you estimate is trapped on that surface should give a guesstimate of how much liquid is trapped.
2)Or perhaps take the amount of packing you know will occupy that volume of column, weigh it dry, wet it out (heres the guess part), weigh it again and the difference is the mass of water retained on the surface. Then use the density of water (~1g/cm^3 at STP) to give you the volume. Again this isnt exact but it might give a rough idea?


FD
PS love your show :handgestures-thumbupright:

PSPS
This was an after thought (which isnt meant to offend anyone who already knows this stuff)..
density water is ~ 1g/cm^3 ( 1 gram per cubic centimeter at standard temp and pressure conditions)
Since 1 cm^3 is = 1 ml
Then 10 grams of water would occupy ~ 10 mL of volume
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Re: Alternative to bubble cap underneath packed column

Postby DrWho » Mon Feb 04, 2013 5:58 am

The HETP calculator shows 4 plates with the 100mm X 180mm section when packed with scrubbers. This is with 1600 W into the column and a RR of 1. Not sure how accurate that is. And not sure how evenly the scrubbers could be packed.

Liquid hold up is a tough one. Measuring the static hold up is easy enough, it is the dynamic hold up that is tougher to measure (but is doable). I still can't vision a packed section of a column holding that much liquid.

???
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Re: Alternative to bubble cap underneath packed column

Postby flyingdutchman » Mon Feb 04, 2013 11:46 pm

Hi,
Yep it would strictly be a rough guesstimate and then only under static conditions (maybe a maximum and minium measurement). I think Mash Rookie and some others have built glass columns to observe packing under normal operating conditions and could be of greater help to you. My guess but its only a guess, is that the packing works best with a thin layer of liquid on the surface and so maximum surface area could result in maximum interaction between the vapor and the liquid. If this is the case then my gut feeling is that the packing does not match the plate for liquid retention when operating efficiently but thats not based on any solid data :(
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Re: Alternative to bubble cap underneath packed column

Postby DrWho » Sat Feb 16, 2013 7:20 am

I had a major ah-ha moment last night while reading through the bubble plate under packed column threads. :happy-bouncyredfire:

It was PP's post, and Smaug's response to it a few posts up from this one that started to churn the gray matter. :think: Then, I read a post from whom I believe was minime. It may have been this one:

viewtopic.php?f=19&t=42&p=16563#p16563

"If you dragged tails the whole run you likely applied too much heat and drew off too fast. (assuming you're column is working as it should)... A good reflux still will be heavily contaminated with tails under 93% from my experience."

That's when it clicked...

On a reflux column the take off rate is limited by not bringing tails up the column. So if we can keep the tails in that deep bath of water that sits on the plate at the bottom of the column. The take off rate can be increased without worrying about them coming up the column. :handgestures-thumbsup:

And we end up with a nice clean drop at a faster take off rate.

???
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Re: Alternative to bubble cap underneath packed column

Postby Spud1700 » Sat Feb 16, 2013 8:25 am

minime wrote:
aqua vitae wrote:Also I does not have a E-ARC, and the only way to really know for sure is to test it as in my example 1... Hopefully someone with an E-ARC will try this and measure time some day so we get hard data, because you are right about your saying about theory :oops:

Your countryman Crystal Skull has the same bubble plate I use.........Wonder how far he is from Rkr :?:

BTW, I'm 200 meters above sea that accounts for some error in the temp probe.


Very good point ref error in the temp probe - people always ask "but my temperature reading on the thermometer says...."

You are not looking at the temp but the change in temperature which will tell you what is going on. Stability in the column is what you are after.
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Re: Alternative to bubble cap underneath packed column

Postby jokkman » Sun Jan 12, 2014 3:04 am

Know this is an old topic but I haven’t read anywhere if someone has tried this … So here is the notes from my tests.

I have tried this with my still, and the main thing that’s different with” Alternative to bubble cap underneath packed column” under my column is that I can do almost 2 times faster product outtake in the beginning of a run (same quality on product) then before!
And with my still I have even less water consumption then before! The outtake speed change is in “heart” it slows down after +2litre to regular outtake speed.
I also discovered that my “tail” are almost gone! Just “little little little” notable after ~3 liters of heart , I even run it down to 30% product outtake but the tail didn’t increase at all… no idea why but it’s a improvement on my still.
It’s also (with my still) stabilized it some, I never changed the water flow under the whole run, usually I have to do this in the middle of the run.

So to summary my testing’s (only done 3 tests)
I’ll keep this under my packed column for my neutral runs, it saves time and some water and “almost” no tail.
Doesn’t have to “watch for the tail” worst thing that can happened for me is that I get some “low wines” in the end…
But….. I haven’t the same setup then most of you here.

My rig
~25 liter kittle, 1000w and 2000w element
35x800 mm copper column, packed with scrubbers and isolated, 7-8 loose packed ss scrubbers.
FAT-FOA on top, copper (some like a CM head… with a twist)
I used my “gin basket” as “alternative bubble cap….” With 7 scrubbers, side by side abut 15cm high.
Mounted the “gin basket” direct on the kettle then column and last my FAT-FOA.
Run it like I usually do, 1000W on product outtake
“Gin basket”: viewtopic.php?f=20&t=1307
FAT-FOA: http://jokkmokk.biz/foa/XL-FOA_beskrivning.pdf (Swedish but you get the design)

So if you already have a “gin basket” like mine and can mount it under your “packed column” you can get a faster outtake speed!
But I’m just a “hobby distiller” running small batches, 25 liters turbo mash most of the times so in a bigger scale I have no clue if it’s worth to do or not……
I am not a complete idiot, some parts are missing....
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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Wed Jan 15, 2014 1:12 am

Thank you very much for sharing your results from this experiment, jokkman :smile:

I am intrigued by the beneficial effect of a bubble ball under a packed column and I was for some time under the impression that the effect was caused by feeding the packed column with a richer vapor from the bubble ball. Your experiment refute my theory as it shows that you can have the same effect with a short larger diameter packed column. So it seems that it is not the type but the size that matters.

In the mean time I found out that the the order of evaporation of substances in a water ethanol mixture are not by their respective boiling points and I now think that the beneficial effect is not caused by feeding the column with a richer vapor but with a cleaner vapor.

This graph (from the book Power Alcohol published in 1922. (page 73)) shows the volatility of ethyl alcohol and amyl alcohol among others.
Values of coefficient k for alcohol and secondary products.jpg
The coefficient k is the ratio of the strength of the vapor and the strength of the liquid. Is the vapor of ethyl alcohol more then 5 times richer than the liquid at 10% ABV, at about 96% ABV (azeotrope) the vapor has the same ABV as the liquid. For amyl alcohol the azeotrope is at 54% ABV. Below that strength there is more amyl alcohol in the vapor as in the liquid, above that strength it is the reverse. It was observed in the late 19th century that fusel oil like amyl alcohol was concentrating in the rectifier column at the level that the volatility of the ethyl alcohol and amyl alcohol are the same (at 42% ABV according to this graph). During the distillation process you are transferring the fusel oil from the boiler into the lower part of the column and with a bubble ball or your gin basket you make enough room to limit the fusel oil concentration thereby preventing column hiccups (stability) and preventing the fusel oil to be carried over in your distillate (higher take off rate). So I think that myles is correct that the issue is [creating] a reservoir of high ABV liquid between the primary boiler and the column.

Going back to the subject of this topic : Alternative to bubble cap underneath packed column, I think that there is a alternative. Instead of making enough room for the fusel oil, removing the fusel oil with a side stream may be as effective. On the Russian forums I found two examples of this approach.
p7290238l small.jpg
I found on the forum homedistiller.ru a post from morfiy (post #28 second page) who did that with a take-off in the lower part of his column. He writes that he opened the valve shortly for two seconds to bleed off 5 ml of fluid and 2 ml of vapor every 15 minutes and that the liquid stinks terribly. On another forum I found a more permanent solution. The valve on the left side at the bottom of the column is marked КЛАПАН ОТБОРА ХВОСТОВ = VALVE SELECTION TAILS according to Google translate :grin:
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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Thu Jan 16, 2014 2:28 am

I missed the golden nugget:
DrWho wrote:That's when it clicked...

On a reflux column the take off rate is limited by not bringing tails up the column. So if we can keep the tails in that deep bath of water that sits on the plate at the bottom of the column. The take off rate can be increased without worrying about them coming up the column. :handgestures-thumbsup:
???


That sums it up quit nicely :handgestures-thumbupright:
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Re: Alternative to bubble cap underneath packed column

Postby Odin » Thu Jan 16, 2014 6:20 am

Why would a bubble cap keep tails and not let them enter the column?

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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Fri Jan 17, 2014 1:45 am

Good question Odin :smile:

The bubble ball is not preventing the tails entering the column but it changes the environment (higher ABV) in such way that considerably less tails are entering the column.
Suppose the boiler charge is 10% ABV. The coefficient k for amyl alcohol goes of the scale in the graph I posted but is about 20. The vapor contains 20 times more amyl alcohol then the boiler content. Suppose the bubble ball content is 40% ABV. The coefficient k for Amyl alcohol is now reduced to 2. In a sense you can say that this lighter component is a lot heavier now.

Going up in the column the coefficient k is reduced to 0,2 at 90% ABV . The vapor here contains 1/5 of the amyl alcohol as the fluid. On it's journey upwards the vapor is stripped from the amyl alcohol.

Where does the amyl alcohol go?

Down the column.

Going down the amyl alcohol becomes the lighter component again as the ABV drops, so it get stuck at about 40% ABV. It will accumulate there and if there is no bubble ball to contain it, it will fill the column and carried over in the distillate.

So how to prevent this when there is no bubble ball?

By increasing the reflux. This raises the ABV of the condensate (at full reflux the condensate (the discharge at the bottom of the column) has the same ABV as the vapor) making the amyl alcohol "heavier" so it is returned back to the boiler.

How to increase the reflux?

By reducing the take-off rate :(
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Re: Alternative to bubble cap underneath packed column

Postby Odin » Fri Jan 17, 2014 2:36 am

Or by upping the power. Or by using a better packing.

And when all ingredients fall like this, it does not change anything. Or is the chart relative to ethanol?

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Re: Alternative to bubble cap underneath packed column

Postby jokkman » Fri Jan 17, 2014 4:56 am

I have no idea why my tail where so "small"…. But I have set a new mash (same “turbo brand”) to do one more test to see if it was the mash that did the “low tail” result.
As soon I have done the run I post the result. But in all my tests I have been able to take out heart faster in the beginning of the run then before but the speed goes back to regular after ~2liters of heart.
I am not a complete idiot, some parts are missing....
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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Fri Jan 17, 2014 9:34 pm

Odin wrote:Or by upping the power. Or by using a better packing.

And when all ingredients fall like this, it does not change anything. Or is the chart relative to ethanol?

Odin.

I don't understand the last sentence :confusion-shrug: The chart is not relative to ethanol.

More power means more reflux to compensate for more vapor, I understand that power is often reduced to prevent flooding and column hiccups.

Better packing, that an interesting one.

I don't know, It will depend on the influence of fusel oil on the effectiveness of packing. If the fusel oil reduces the effectiveness of packing, replacing the original packing with a better one creates more room for the fusel oil as a shorter section of packing is needed to increase the ABV to more then 90%. The effect of a bubble ball would be that the height of the column can be reduced. If there is no influence, a better packing result in less space for the fusel oil and such a column would benefit by mounting a bubble ball.

Test it out, mount a gin basket (I don't know if you have such a thing, I just making this up ;-) ) filled with a suitable packing from a iStill 250 on a iStill 50 and see what it does. This can go multiple ways, if it doesn't help you can advertise that your still is so good that it does not need no stinking bubble ball, if you can reduce the height of your still it might be more attractive to buy and if it works it's a nice add-on you can sell ;-)
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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Sat Jan 18, 2014 4:39 am

Just some more thoughts.

A better way to describe what is going on is to see the rectifying column as a fusel oil trap. Fusel oil is fed into into the column and there is no way to escape until the column is saturated and the fusel oil seeps through. Fusel oil increases the boiling point and the raise in temperature make the iStill going into stabilizing mode (full reflux). In my humble opinion “column cleaning mode” would be a better description as the fusel oil is flushed out of the column. Then the cycle starts over again.

But is flushing the fusel oil back into the boiler the right thing to do? Why not dump the content of the column into a separate vessel? So the fusel oil is removed from the system.

Maybe you can decant the content of this vessel by mixing it with cold water to salvage the ethanol, like it is done in a ethanol plant.

Just thinking :smile:
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Re: Alternative to bubble cap underneath packed column

Postby Odin » Sat Jan 18, 2014 5:10 am

The easiest way to get rid of tails is to collect them seperately and hydro seperate them. Together with heads. Dilute to under 17% with water, heads sink down, tails float on top, siphon off everything in between for re-distilling.

The problem with the tails trap is that there is a time in distilling when it is of no use (first part of the hearts run) and there may be a time when it is beneficial (towards the end of hearts). Deciding between them is going to be tricky.

Yes, when temps go up, the iStill re-stabilizes, that's correct. In the end of the run this means that higher bp alcs are flushed out of the column and into the boiler.

On packing: it is not the question if fusil oils have an influence on packing efficiency, but that a more efficient packing creates more re-distillations and so holds fusils abay much longer. That was the point I was trying to make, Edwin.

Regards, Odin.
"Great art is created only through diligent and painstaking effort to perfect and polish oneself." by Buddhist filosofer Daisaku Ikeda.
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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Mon Jan 20, 2014 5:15 am

jokkman wrote:.... I used my “gin basket” as “alternative bubble cap….” With 7 scrubbers, side by side abut 15cm high.
Mounted the “gin basket” direct on the kettle then column and last my FAT-FOA.…


Diameter of your gin basket is 90 mm and the height is 290 mm.

I have the following question: are these 7 scrubbers resting on the bottom of the ginbasket so that there is a open space of 140 mm above the scrubbers?

Thank you in advance :smile:

Regards,

Edwin
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Re: Alternative to bubble cap underneath packed column

Postby jokkman » Tue Jan 21, 2014 6:45 pm

@Edwin Corissant
Yes, you got it right ;)
I think you can put in one more scrubber in that size of tube, it wasn’t “a tight fit” in my gin head with 7 scrubbers. The scrubbers was “resting on the bottom”, standing like standing “hotdogs in a can”. Abut 150mm high and open space above them, abut 140mm

What's your distilling goal, are you going for "clean vodka" or flavored spirits?
Or maby a mix.... ?
I am not a complete idiot, some parts are missing....
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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Wed Jan 22, 2014 10:56 pm

@jokkman, thank you!

De reason I asked is that amyl alcohol demixes above a concentration of 3% if I recall correctly, and as amyl alcohol raises the boiling point, the sudden drop in boiling point of the remaining ethanol water mixture cause a column hiccup. In the industry column hiccups can cause severe structural damage to the internal parts of a column like dislocated trays. In the industry we use hydraulic accumulators at the end of a pipeline to prevent water hammer. I think that the open space between the two sections of packing isolate the column from the violent action below in a similar manner. This might explain the stable operation of the bubble ball - column combination.

My goal at this moment is to get a full understanding of the distilling process. I got interested about a year ago and the more I learned the more I wanted to know. I am hooked :grin: One day I want to make a small continuous still: 500 ml per hour ethanol, less then 1 kW power. I don't know if I will succeed but the fun is in the trying :grin:
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Re: Alternative to bubble cap underneath packed column

Postby jokkman » Tue Feb 11, 2014 8:03 am

I have now done another test with “Alternative to bubble cap underneath packed column” and I got the same result, much leaner tail and faster outtake on the heart… I can’t explain why??
I did the run on the same turbo mash brand as before and had it “fermenting” for 2week before I distill it.
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Re: Alternative to bubble cap underneath packed column

Postby Edwin Croissant » Wed Feb 12, 2014 2:13 am

For a water ethanol mixture with a small amount of amyl alcohol (one of the fusel oils) the coefficient k for the amyl alcohol is:

    20 at 10% ABV (there is 20 times more amyl alcohol in the vapor then in the liquid)

    2 at 40% ABV (there is 2 times more amyl alcohol in the vapor then in the liquid)

    0.2 at 90% ABV (there is 1/5 the amount of amyl alcohol in the vapor then in the liquid)

For amyl alcohol the azeotrope is at about 54% ABV.

So (bad analogy) amyl alcohol in a column behaves like a helium balloon. When released it is lighter than air and goes up until it has the same density as the surrounding air. Hoist the balloon higher and it will decent after release. At the end of the 19th century it was discovered that the highest concentration in a column occurred where the coefficient k of ethanol and amyl alcohol are the same and that is at about 40% ABV.

From the viewpoint of the amyl alcohol the column is a trap. It is forced in with no way out, until the column is saturated and it is forced through.

How to prevent this:

    Flush the amyl alcohol continuously out with extra reflux. Take-off rate is greatly reduced

    Make room for the amyl alcohol at 40% ABV, mount a bubble ball under your column, or jokman's ginbasket :lol:

    Make a take-off at 40% ABV

    Repeatedly flush the amyl alcohol out of the column by going into full reflux

So that is what I am thinking, you created room for the fusel oil with your ginbasket :handgestures-thumbupright:
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Re: Alternative to bubble cap underneath packed column

Postby eXa » Wed Mar 19, 2014 5:06 am

This is quite interesting, Im still collecting parts for my future VM/LM column, so i can still make changes in the design.
Since im height limited, how low can this bubble cap be made? Currently i have ~120-130cm wich can be filled with scrubbers. Would it be worth taking some of that height and replace it with a bubble cap?
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Re: Alternative to bubble cap underneath packed column

Postby eXa » Wed Mar 19, 2014 11:46 am

This is really interesting. How small can i make the bubble plate piece on my future 2" VM/LM?
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