Fractionator

Fractionator is a distillation column designed to separate a liquid mixture into fractions according to boiling points. It operates by repeated vaporization and condensation as vapor rises through a packing or trays, creating multiple equilibrium stages. Lighter components tend to rise to the top and are withdrawn as overhead product, while heavier components are drawn off at the bottom as bottoms. The column is heated by a reboiler at the base, and a condenser at the top liquefies part of the vapor; a reflux stream returned to the column improves separation by increasing the vapor-liquid contact and effectively increasing the number of stages.

Design parameters include the number of theoretical stages, the type of internals (tray vs packing), the feed location, the reflux ratio, and the column operating pressure. Tray columns use perforated plates; packed columns use random or structured packing to provide surface area for phase contact.

Fractionators are central to petroleum refining, where crude is separated into fractions such as naphtha, kerosene, diesel, and gas oil, and in chemical plants to isolate solvents and intermediates. In gas processing, fractionators recover light hydrocarbon streams; specialized columns such as depropanizers, debutanizers, and stabilization columns are common.

Safety and energy efficiency are important concerns; fractionators are designed to minimize energy consumption and manage hazards from flammable vapors, high temperatures, and corrosive feeds. The concept dates to early fractional distillation work in the 19th century and remains essential to modern process engineering.