Question

What is a fractioning tower/column?

Answer 1

*fractionating*

Answer 2

Source:
http://en.wikipedia.org/wiki/Fractionating_column
A fractionating column or fractionation column is an essential item used in the distillation of liquid mixtures so as to separate the mixture into its component parts, or fractions, based on the differences in their volatilities. Fractionating columns are used in small scale laboratory distillations as well as for large-scale industrial distillations.

Answer 3

A fractionating column is unique from a typical distillation apparatus due to the presence of some material with high surface area that allows for the separation of substances that have similar boiling points. In essence, the extra material in the column increases the amount of reflux (the vaporization-condensation cycle) such that the components are better separated into cleaner "fractions" of the original mixture.