Spirit Stills and Reboilers?

[Ralph Katzenell]

Greetings Jesper. In short, no go.

Although Little Green Maxwellian Demons operating speed flaps are used in theoretical constructs to illuminate concepts when teaching thermodynamics, they are only ever found as real entities in the pages of the Guardian and occasionally on BBC.com.

In whisky stills, vapour is a macroscopic entity, and individual molecular speeds cannot be used to separate out the higher temperature molecules from their slower brethern. (Incidentally, even then the spread is pretty narrow).

You can, of course, extract heat, and progressively grab those wimpish molecules that cant stand the cold and slow down a bit and start clumping together. They call it fractional distillation.

But as the Laws of Thermodynamics say " You cant win, you can only break even", followed quickly by "You can only break even at absoute zero", and then they take away that little residual hope with "Tough luck, you can't get absolute zero - ever".

Uncle Ralph

----- Original Message -----
From: "J. Stephen Lure" <jstephenlure at YAHOO.COM>
Date: Monday, August 7, 2006 3:36 pm
Subject: Re: Spirit Stills and Reboilers?
> Hi Ralph, 
>  
> The temperature of a liquid or a gas is a mean value. Some 
> molecules are hotter (faster) and 
> some colder (slower). Shouldn’t this fact make it possible to 
> reach higher temperatures 
> “downstream”? And couldn’t the condensing process in the reboiler 
> provide the heat for distillation 
> of the lighter fractions? (It was more than 20 years since I 
> studied thermodynamics, so most of 
> that knowledge has unfortunately become entropy.) 
>  
> Regarding thumper/doubler – I’ve read somewhere that it (on an 
> average) raises the abv. with 
> five percentage points. 
>  
> Cheers, 
> JESPER 
>  
> “From the point of view of common-sense if a still is heated to 
> cause boiling evaporation the 
> temperature of the vapor coming off is the same as the temperature 
> at which the liquid is 
> boiling. Nothing in the downstream heat-exchange chain can ever 
> get to a higher temperature 
> unless heated by another heat supply at higher temperature 
> (excluding discussion of vacuums or 
> rapid volume compression here) [...]. 
>  
> /Ralph 
> 
>         
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