Process of separating a mixture and dividing it into a number of smaller quantities / fractions in which the composition changes according to a gradient.

Natural Gas Liquid Fractionation

Once NGLs have been removed from the natural gas stream, they must be broken down into their base components to be useful. That is, the mixed stream of different NGLs must be separated out. The process used to accomplish this task is called fractionation. Fractionation works based on the different boiling points of the different hydrocarbons in the NGL stream. Essentially, fractionation occurs in stages consisting of the boiling off of hydrocarbons one by one. The name of a particular fractionator gives an idea as to its purpose, as it is conventionally named for the hydrocarbon that is boiled off. The entire fractionation process is broken down into steps, starting with the removal of the lighter NGLs from the stream. The particular fractionators are used in the following order:

•Deethanizer – this step separates the ethane from the NGL stream.
•Depropanizer – the next step separates the propane.
•Debutanizer – this step boils off the butanes, leaving the pentanes and heavier hydrocarbons in the NGL stream.
•Butane Splitter or Deisobutanizer – this step separates the iso and normal butanes.

By proceeding from the lightest hydrocarbons to the heaviest, it is possible to separate the different NGLs reasonably easily.