RE: FW: 2m Column
> if i have a column tall enough eg 2 or 3 metres do i reallyYou will always need some reflux. Without that liquid flowing back down
> need any reflux at all.
over the packing, there will be nothing to purify the rising vapour.
You'd just have a tall pot still.
If you didn't insulate the column, then there might be some condensing
happening on the sides of the column, and refluxing, but thats not what you
want. Its too uncontrolled, and wont do the job properly. You want the
reflux to be a deliberate action, generated above the top of the packing
(so that it gets to flow down over all the packing). If it were just off
side cooling, then its not using the full height of the column, and it wont
be distributed well through the packing.
A taller column will allow you to run less reflux (eg say 3:1 instead of
4:1), but it will always require reflux, and still a good proportion of it.
A taller column is only of use if the reflux is using all that height.