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Offline fli  
#1 Posted : Tuesday, April 15, 2008 12:36:00 PM(UTC)
fli


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Hi, new to this forum have been seeking information on the reflux still construction and operation looking to produce ethanol on a small scale as a safer alternative to methanol in the biodiesel production process. I have come across several very useful websites giving pretty detailed instruction on components and construction of reflux towers and condensers. something I see consistently is the condenser coolant lines are always run through the tower at specified intervals. It is such a short section of copper that it doesn't seem as though it would do much more than help add rigidness to the unit as a whole when the dog bolts through and takes it for a ride when his leash catches it. Unless it triggers some sort of avalanche condensation process or requires such a small surface area to produce a functional task. Can someone give me some more insight on exactly what function this segment of construction accomplishes in the reflux process. thanks in advance for any insight, Fli
Offline al_the_chemist  
#2 Posted : Tuesday, April 15, 2008 4:21:04 PM(UTC)
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"Welcome to the forum Fli.

You can find great breakdown of the methods and uses of a reflux still online, I would also recommend buying "The compleat distiller" (nope not a type-o, odd name for a book), if you really want to get into the nitty gritty of it.

Over all the tubing going through the top of the column does have a major effect on the reflux process. When the vapors hit the crisscrossing surface of those tubes which are at a MUCH lower temperature due to the coolant water, They get forced back into liquid form and thrown back down to the column for an additional run in the reflux process. Think of this as a traffic cop at the top of your tower. It helps you regulate just how much vapors are forced back into the reflux process. I usually keep the tower top at full flow for a while to allow the tower to reach a stable reflux fractioning, and then gently lower the current to allow the heads to start flowing through.

-Al"
Offline fli  
#3 Posted : Thursday, April 17, 2008 1:35:59 PM(UTC)
fli


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Thank you that confirms my understanding. And I will be looking into the book you mentioned. Am I correct in assuming that by full flow you are referring to the coolant flowing through the tube at maximum flow in turn producing maximum precipitation in the tower? and then after it has cycled a few times slowing the coolant flow allows the temperature at that section of the tower to rise enough to allow a portion of the vapors to pass but still keeping the condenser cool enough where it can precipitate what makes it past and drain off via gravity? Thanks again for your input
Offline fli  
#4 Posted : Saturday, April 19, 2008 11:40:24 PM(UTC)
fli


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"Thanks again Al,
I found a digital text copy with illustrations of ""The Compleat Distiller"" available to read online I find the book very useful and easy to follow. The author even gets into technical math which is unnecessary to understand the information the book provides, but even at that the technical math is put into terms that doesnt require advanced college math to comprehend. Thought others might benefit by it here is a link as copied and pasted from my toolbar, hope it takes you there, when you first open the page there is a digital photo of a kitty cat in the window that contains the book if you scroll past it you get to the book including the cover. http://www.scribd.com/doc/2319233/The-Compleat-Distiller-by-Stone-Saxon"
Offline al_the_chemist  
#5 Posted : Monday, April 21, 2008 7:16:12 PM(UTC)
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"Glad to help,

And yes, your understanding of the process is correct"
Offline johnpierce79  
#6 Posted : Tuesday, January 06, 2009 7:20:44 AM(UTC)
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"""The problem with pot stills is that they don"t do a good job at separating out exactly what you want to distill as output. They are usually used to separate compounds whose boiling points differ by about 100º C. When fermented liquid is distilled, lots of things come out, some good, some bad. And because there are no fine controls on this kind of still, the output contains a lot of impurities. Nevertheless, after each distillation, you always get a better output product from that which you started with. So each time you redistill the output in a pot still, it will come out a bit purer, but you lose a little each time you redistill. To make it really pure, you have to distill it so many times that you"ll end up with almost no output. If you don"t re-distill the output several times, you can get a massive hangover by drink whatever comes out. Hangovers are caused by the impurities in the alcohol. In short, you"ve been poisoned (but just a little bit)!"



"Basically, the reflux still is a structure that allows the distillate vapors from a boiler to rise up a column to the top where the vapors are condensed. The condensed liquid is then allowed to run back down through the rising vapors to a point where the temperatures become hot enough that it boils again. This process is called refluxing. As this cycle continues, the mixture inside the tower is effectively re-distilled. In the process, the components of the mixture separate into discrete layers within the column based on their boiling points." "At the time of this writing, there is only one like it.""
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