Reboiler

A reboiler is a heat exchanger located at the bottom of a distillation column. Its primary function is to provide the heat necessary to boil a portion of the liquid from the column’s bottom, generating vapor that rises through the column to sustain the separation. By supplying latent heat, the reboiler helps control the bottom temperature and composition of the feed to the column.

In operation, heat is transferred from a chosen heat source, commonly steam, into the bottom liquid. The boiled portion creates vapor that travels up the column, while the remaining liquid is returned to the column as bottoms. The reboiler must maintain an appropriate liquid level and heat duty to achieve the desired separation without flooding or excessive vapor generation.

Two common types are kettle reboilers and thermosyphon reboilers. A kettle reboiler uses a separate vessel containing the bottom liquid that is heated by steam in tubes or jackets. A thermosyphon reboiler relies on natural circulation to move liquid between the reboiler and the column without a pumping mechanism. Other variations include forced-circulation or electric-heated configurations, chosen based on duty, fouling tendencies, and maintenance considerations.

Design and operation considerations include heat duty, boiling regime, materials compatibility, risk of fouling, and proper control of steam flow and liquid level. Safety and reliability are addressed with appropriate relief devices, corrosion resistance, insulation, and monitoring of temperature and pressure.

Reboilers are widely used in petroleum refineries, chemical plants, and natural gas processing to enable efficient distillation and product recovery by supplying the necessary energy to bottom streams.