28086Multi-column balancing (was) Re: Mike Nixon - Vapor Management question
- Mar 2, 2005--- In Distillers@yahoogroups.com, "Mike Nixon" <mike@s...> wrote:
> Multiple columns are tricky, so sneak up on them with caution.
> just the matter of getting the reflux ratio in each columncorrect, but you
> also have to achieve a balance between them, and maintain it. Ifthe vapor
> feeds are not set up properly then you can get an unstablecondition that
> will end up with one or more columns cutting out entirely.I assume the reason people want multiple columns is to increase the
> All the best,
> Mike N
amount of product taken in a given timeframe. However large
diameter pipe is not easily found, so multi-columns is a viable
The simplest way to achieve perfect balance is to connect all the
column TOPS together BEFORE the condenser and use a single takeoff
point for product.
It's simple fluid dynamics. A system joined at one end (by the
boiler) will always have pressure differences in the legs (columns),
just like a garden watering system where the sprays are uneven.
However, if you make said watering system a closed loop, then all
sprays have equal pressure. The same is true for multiple columns.
Join the multiple columns at the boiler, and again at the top, then
run to a condenser. This setup will of course require more power to
drive it, because of the additional volume to fill in the extra
columns, but that's the whole point of the exercise, isn't it?
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