I see both fractionation and fractionating (maybe the latter being a bit more common) are used

Fractionation (physical separation) is the separation of hydrocarbons in distillation towers into groups of hydrocarbon compounds of different boiling-point ranges called "fractions" or "cuts"
http://local.exxonmobil.com/AP-English/Files/SCP_SRbro.pdf

Tower Internals
AMACS has vast experience in providing total solutions for process column applications. Process columns vessels and drums often have internal access challenges as well as variable operating liquid, vapor and temperature ranges that require special consideration when designing, fabricating and installing process internals.
We design and fabricate a full range of custom tower internals for your process requirements. AMACS offers one of the industry’s most complete lines of replacement-in-kind, non-pressure retaining, process tower internals.
http://www.amacs.com/fractionation-tower-internals/

The purpose of the mechanical design, on the other hand, is to select the tower internals, column diameter and height. In most cases, the mechanical design of fractionation towers is not straightforward. For the efficient selection of tower internals and the accurate calculation of column height and diameter, many factors must be taken into account. Some of the factors involved in design calculations include feed load size and properties and the type of distillation column used.
https://en.wikipedia.org/wiki/Fractional_distillation

How do fractionating towers in a refinery work
https://www.quora.com/How-do-fractionating-towers-in-a-refin...