Re: Does size matter?
> Hey Neighbor,
> I recently asked these questions in private to one of the more
> knowledgeable members and was told that 36" of packing length was
> sufficient in a 2 inch column to achieve maximum Purity. You do
> lot of 48" and even taller columns out there, I had just alwaysover
> wondered if it was necessary. The taller columns may be a carry
> from the days when Marbles and Rashig Rings were the availablepacking.
> They have a small amount of surface area compared to Scrubbers andto
> Structured packing therefore you would need a taller column of them
> get more theoretical plates. Could one of you reflux guys (Riku,Hi Mason.
> Harry) confirm or deny this assumption?
In my case, having a HJ cross flow-dual head still that has about 71
inches x 2 inch column that is packed with Amphora mesh, which does
include the boiler or the section for the VM take off and cross
condenser. Yes its tall, but for a reason you did not mention.
And that is vapor speed through the column. If the ethanol/water
vapor is too fast through the column packing it will require a
higher reflux ratio to achieve the % you want, which takes more time.
My boiler is a 20-litter hot water urn, 20 L to the brim; it's kind
of small but suits my time frame. The original element is 2400
watts, I added a still spirits 1100 watt element for the spirit run.
So as we all know the best wattage element for a spirit run is about
750 watts, right? I already had the crappy still spirits still, so I
used the element from that and added to my free hot water urn. To
compensate for the extra heat/vapor velocity , I needed to add more
theoretical plates to achieve the separation I hope for. I get 95.
what ever %, every time. You still got to the heads and tails thing
but it happens in a shorter period.
Conclusion: add vapor velocity /element wattage/ reflux ratio to the
reason if you want? I'm talking about balancing the still, I know
there's much more to it and Harry was just giving a simple yes and no
Ps, I'm way over my head on this, but the "vapor velocity" subuject,
has been talked about before.