fractional condensation??
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fractional condensation??
Ok let me start this by saying... this is purely a thought experiment at this point.
I had a dream a while back, and in that dream I was helping some dude build a super complex still. I didn't understand how it worked... even now its a little fuzzy.
it started with a pretty standard vm reflux column. but on the output branch there were several small boilers with their own condensors that had different liquids in them that boiled at ever lower temperatures than the preceding one. the vapor tube ran through the center of the boiling chambers.right after each "cooling" chamber there was a small downspout with a p-trap style bend in it so it would allow liquid to come out but not vapor. in my dream the guy was able to set it up so heads, hearts, and tails or water came out automatically from different outputs!!
Is this just a crazy dream? or something that might be feasible?
any thoughts?
I had a dream a while back, and in that dream I was helping some dude build a super complex still. I didn't understand how it worked... even now its a little fuzzy.
it started with a pretty standard vm reflux column. but on the output branch there were several small boilers with their own condensors that had different liquids in them that boiled at ever lower temperatures than the preceding one. the vapor tube ran through the center of the boiling chambers.right after each "cooling" chamber there was a small downspout with a p-trap style bend in it so it would allow liquid to come out but not vapor. in my dream the guy was able to set it up so heads, hearts, and tails or water came out automatically from different outputs!!
Is this just a crazy dream? or something that might be feasible?
any thoughts?
Re: fractional condensation??
look up something called a Coffy Still. circa 1845.
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Re: fractional condensation??
While I'm having trouble envisioning what you are saying precisely, I got the gist. People have made heads traps and such. If you are going for a flavored spirit this would not be the way to go. But a neutral would greatly benefit from this.
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Re: fractional condensation??
john2674 it doesnt work, you cant separate by condensation. Separation only occurs on evaporation, on condensation, everything condenses at once regardless of temperature.
Re: fractional condensation??
Ok Manu, I read your post and thought about the statement that it cant be done.....Had thoughts about the scientific laws that state for every action there is an equal and opposite reaction. So I researched some more. Heres what I found when I put on my lab coat lol.
fractional condensation Is possible!
BUT... it is primarily used to remove highly volatile compounds in oil production of several types.
For the purpose that I was proposing, the condensation points of all of the fractions in our product is so close that , at best, it would be extremely difficult to achieve the exact temperatures required to make it happen.
so I hate to admit it but you were pretty much right, just a way shorter answer ..lol
fractional condensation Is possible!
BUT... it is primarily used to remove highly volatile compounds in oil production of several types.
For the purpose that I was proposing, the condensation points of all of the fractions in our product is so close that , at best, it would be extremely difficult to achieve the exact temperatures required to make it happen.
so I hate to admit it but you were pretty much right, just a way shorter answer ..lol
Re: fractional condensation??
One common example of fractional condensation is a dephlegmator, another is separation on column trays.
In petro refinery columns continuous product separation on collection trays by temperature control is essential.
In petro refinery columns continuous product separation on collection trays by temperature control is essential.
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Re: fractional condensation??
im right because we all had the same idea as you and some spent a fortune building huge stills that didnt work. I was lucky enough to read early a great account of such failure and why this doesnt work in Barbet "manuel de distillation" from 1880's.
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Re: fractional condensation??
Fractional condensation works just fine. Coffey Stills were banned from Irish Whiskey and Cognac production (and a few other disciplines) because of flavor considerations, but that doesn't mean the fractional condensation they depend on doesn't work. Continuous stills are still used for Bourbon and Canadian, as well as petroleum. My dephlegmator, without trays or packing, changes the composition of the product in a measureable way, illustrating fraction condensation in front of me.
Barbet's book is a must read for distillation.
Barbet's book is a must read for distillation.
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Re: fractional condensation??
Coffey still doesnt use fractional condensation ̣(because it doesnt exist), are we talking about the same thing ?heartcut wrote:Fractional condensation works just fine..
By fractional condensation I mean the ability to condense various gases (boiled off a liquid mix) selectively based on the temp selection.
Re: fractional condensation??
That's what a dephlegmator does, the balance and composition of phlegm and vapor depends on the coolant flow.
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Re: fractional condensation??
no, a deflegmator is just a condenser and it condenses everything blindly (apart from air and such), the amount it condenses depends on the coolant but the composition of the condensate doesnt depend on it.heartcut wrote:That's what a dephlegmator does, the balance and composition of phlegm and vapor depends on the coolant flow.
It is counter intuitive but that's how it works. The separation occurs on evaporation NOT on condensation.
The amount of reflux depends on the dephlegmator and influences the % of the ethanol on top, but that's because of reflux which is another mechanism
Re: fractional condensation??
Manu is right. The composition change in your flute is due to the fact that when a mixture of ethanol and water boils, the vapor created is richer in ethanol than the liquid was. For example, when a 15% wash boils, the vapor is 65% alcohol. When a 30% wash boils, the vapor is 72.5%. But when the vapor condenses, the resulting liquid remains 65% or 72.5%
Distilling at 110f and 75 torr.
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Re: fractional condensation??
Quoting from:
Handbook of Laboratory Distillation
By E. Krell 1982
5.2.3 Separation by partial condensation
The term partial condensation is used to denote the liquefaction of a fraction from a flow of vapour. It can be brought about deliberately by interposing a special condenser- a so-called dephlegmater- in the vapour line, and it also occurs as an undesired effect by loss of heat from an insufficiently insulated column.
(1 illustration and a paragraph later)
In industry it is common to make a dephlegmater produce the reflux and cool the distillate to be drawn off in a production condenser. The aim is to use the amplifying effect of the dephlegmater which is due to the partial condensation of the high-boiling components.
End quote.
I do understand that the tube in shell dephlegmators commonly used in Flutes are difficult to modulate at low flows and wouldn't be that great for this technique. I use a coil dephlegmator that tunes easily at partial condensation rates. Also been using partial condensation in petroleum refineries for the last 4 decades and the refineries have been doing it a lot longer.
Handbook of Laboratory Distillation
By E. Krell 1982
5.2.3 Separation by partial condensation
The term partial condensation is used to denote the liquefaction of a fraction from a flow of vapour. It can be brought about deliberately by interposing a special condenser- a so-called dephlegmater- in the vapour line, and it also occurs as an undesired effect by loss of heat from an insufficiently insulated column.
(1 illustration and a paragraph later)
In industry it is common to make a dephlegmater produce the reflux and cool the distillate to be drawn off in a production condenser. The aim is to use the amplifying effect of the dephlegmater which is due to the partial condensation of the high-boiling components.
End quote.
I do understand that the tube in shell dephlegmators commonly used in Flutes are difficult to modulate at low flows and wouldn't be that great for this technique. I use a coil dephlegmator that tunes easily at partial condensation rates. Also been using partial condensation in petroleum refineries for the last 4 decades and the refineries have been doing it a lot longer.
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Re: fractional condensation??
I'm listening and wish to learn.
Which fraction do you selectively condense, the water or alcohol? At what temperature does this occur?
Which fraction do you selectively condense, the water or alcohol? At what temperature does this occur?
Distilling at 110f and 75 torr.
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Re: fractional condensation??
I believe "partial" here is to be understood as a part of the output is to be returned as reflux.heartcut wrote:Quoting from:
Handbook of Laboratory Distillation
By E. Krell 1982
5.2.3 Separation by partial condensation
The term partial condensation is used to denote the liquefaction of a fraction from a flow of vapour. It can be brought about deliberately by interposing a special condenser- a so-called dephlegmater- in the vapour line, and it also occurs as an undesired effect by loss of heat from an insufficiently insulated column.
(1 illustration and a paragraph later)
In industry it is common to make a dephlegmater produce the reflux and cool the distillate to be drawn off in a production condenser. The aim is to use the amplifying effect of the dephlegmater which is due to the partial condensation of the high-boiling components.
Re: fractional condensation??
Read the quote again- the "partial condensation of the high boiling components" indicates a composition change.
Read the book- that chapter includes some "before and after" dephlegmater composition examples.
While trouble shooting refinery process I am sometimes in a position where I watch the composition change on an analyzer in real time as well as reading about it in textbooks.
Read the book- that chapter includes some "before and after" dephlegmater composition examples.
While trouble shooting refinery process I am sometimes in a position where I watch the composition change on an analyzer in real time as well as reading about it in textbooks.
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Re: fractional condensation??
The Krell text is very disturbing. Here's a quote from Barbet :
Chapter "Le condenseur n'est pas un analyseur" start at PDF page 326 (book page 308) explains the whole thing and ends with this : it says if you see changes in composition at the condenser it's because it refluxed things downwards that have been reboiled on the plates not anything else.
I'll add that from all the column diagrams i've seen, which often come from the petroleum industry, the condensers are *always* on top, condensing everything, then the liquid is split between output and reflux, I cant remember seeing a diagram with condensers along the way or on top but condensing just part of the gases (as in partial condensation).
Chapter "Le condenseur n'est pas un analyseur" start at PDF page 326 (book page 308) explains the whole thing and ends with this : it says if you see changes in composition at the condenser it's because it refluxed things downwards that have been reboiled on the plates not anything else.
I'll add that from all the column diagrams i've seen, which often come from the petroleum industry, the condensers are *always* on top, condensing everything, then the liquid is split between output and reflux, I cant remember seeing a diagram with condensers along the way or on top but condensing just part of the gases (as in partial condensation).
Re: fractional condensation??
I was using the term "analyzer" to refer to a Gas Chromatograph or Spectrograph analyzing the composition of the process stream. Don't know what else to say after watching these effects in real time. Good luck.
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Re: fractional condensation??
Barbet was talking about ethanol and heads.heartcut wrote:I was using the term "analyzer" to refer to a Gas Chromatograph or Spectrograph analyzing the composition of the process stream. Don't know what else to say after watching these effects in real time. Good luck.
These real time effects (I understand instantaneous) that you see, are they with components with very far boiling points ?
Re: fractional condensation??
One example was C6 to C12 straight chain, ~100 to 140degC.
Another was naptha and gasoline (hundreds of components) in the ~30 to 70degC range.
As the reflux ratio increased the concentration of low boiling point components increased after the condenser.
Another was naptha and gasoline (hundreds of components) in the ~30 to 70degC range.
As the reflux ratio increased the concentration of low boiling point components increased after the condenser.
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Re: fractional condensation??
Another thought:
Running my 4" without plates (potstill mode) but with the dephlegmator available I can hold up the nasty part of the tails for an additional flavorful quart (12 gal charge) by flowing water through the RC at the end of the run.
Running my 4" without plates (potstill mode) but with the dephlegmator available I can hold up the nasty part of the tails for an additional flavorful quart (12 gal charge) by flowing water through the RC at the end of the run.
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Re: fractional condensation??
Sorry for this aside.....
Is there a link to an English translation of Barbets book?
Tom
Is there a link to an English translation of Barbets book?
Tom
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Re: fractional condensation??
noTomb wrote:Sorry for this aside.....
Is there a link to an English translation of Barbets book?
Tom
Re: fractional condensation??
Sorry...do you mean that you are certain an English translation does not exist?
Or that you do not know where to get one.
(Others have mentioned it as required reading)
Tom
Or that you do not know where to get one.
(Others have mentioned it as required reading)
Tom
Re: fractional condensation??
This should get you there in French:
https://books.google.com/books?id=lz5KA ... on&f=false" onclick="window.open(this.href);return false;" rel="nofollow
https://books.google.com/books?id=lz5KA ... on&f=false" onclick="window.open(this.href);return false;" rel="nofollow
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Re: fractional condensation??
smiles..... You completely misunderstand the theory of distillation.manu de hanoi wrote:john2674 it doesnt work, you cant separate by condensation. Separation only occurs on evaporation, on condensation, everything condenses at once regardless of temperature.
If your condensor is below the boiling temperature of the lightest element, AND the condenser has "enough" energy absorption, you will condense "everything."
However, if the temperature of the surface of the condensor is above boiling temp of the lighter components, the lighter components will indeed tend to not condense.
When done, this is how a reflux still works - the water TENDS to condense out, the alcohol TENDS to not. The water TENDS to not want to boil off, the alcohol tends to boil off more quickly.
To pull partials, you COULD take a typical reflux still capable of making 95 percent. Lengthen the column 30 percent to give some "room".
Put a temperature probe in the column about 20 percent from the top of the packing (inside your "room").
Then run the still in full reflux, watching the temp of the vapor just before the top condenser, and the one part way down the column. If you have "heads" you will soon see the top of the column will have a lower temp then one 20 percent down. Pull product from the top, or pull product from 20 percent down.
Take that further, and you can take product from whatever temperature range you want. If you pull product too fast, you will get water percent coming up, your temps will plummet (by 2 or 3 degrees as a first warning).
Now I know how you claim azeo so easy, it's based on a meat thermometer. :lol:
Re: fractional condensation??
I don't see where that proves anything about fractional condensation. Your example is easily explained by the fact the heat source is at the bottom and reflux mingles with vapor to combine into a new mixture with a boiling point described by the familiar graph.
You are saying that you can take azeotrope off a CM still in a single pass by holding the reflux condenser at 86.5c, right?
You are saying that you can take azeotrope off a CM still in a single pass by holding the reflux condenser at 86.5c, right?
Distilling at 110f and 75 torr.
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"
Re: fractional condensation??
The familiar graph.
Distilling at 110f and 75 torr.
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"
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Re: fractional condensation??
Yes. You can pull 95 percent ethanol off a reflux still in a single pass.skow69 wrote:I don't see where that proves anything about fractional condensation. Your example is easily explained by the fact the heat source is at the bottom and reflux mingles with vapor to combine into a new mixture with a boiling point described by the familiar graph.
You are saying that you can take azeotrope off a CM still in a single pass by holding the reflux condenser at 86.5c, right?
With a batch still, I thought this all through some more. With a batch still, you will always have the lightest product at the very top, and it makes no sense to try to make it fractional.
My head is stuck in continuous stills, and with a continuous still if you want to separate the products from each other you must use fractional or make a second pass through a batch still.
So, I was wrong, and made things more confusing. sorry.
Now I know how you claim azeo so easy, it's based on a meat thermometer. :lol: