## Re: vapour speed

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• ... for ... the ... of ... You got it right. ... a ... the ... Well, I ve been using plain vaporspeed as an indicator of how well it works. According to M.
Message 1 of 2 , Dec 28, 2003
wrote:
> Hi all,
> I hope everyone had a fun and safe Christmas!  I'm just waiting
for
> life to go back to normal. I went to buy some plumbing fittings for
> my new still just to find everyone still on holiday! Bah Humbug!
> Anyway I was thinking  How do you calculate the speed at which
> vapour is traveling up a column? I imagine you would work out how
> much vapour is been produced per second ( with power input) find
the
> volume it occupies  find the volume of the column  divide volume
of
> vapour by the column volume and that would give you the speed?

You got it right.

> which leads to my next question how long does the vapour need to be
> in contact with the packing to get one separation/plate? - using
a
> standard calculable packing e.g. Marbles/ structured copper mesh etc
> There are probably hundreds of things I'm not taking into
> consideration but a rough guide would be good enough to work out
the
> dimensions and power settings for my next still
> Can anyone help shed some more light on this??
>

Well, I've been using plain vaporspeed as an indicator of how well it
works. According to M. Nixon vaporspeed should be kept below 20"/s,
in practise you'll enter flooding/choking soon after that. As an
example PDA-1 is recommended to use 12"/s and I use 5"/s (30cm long)
in my spiral/column still. Packing in these assumptions is scrubbers
or mesh. One thing you need to take into account is power losses
before any vapor enters the column, it's quite easy to loose over
500W through uninsulated boiler.

Greetz, Riku
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