Properly design thermosyphon reboilers

Thermosyphon tower reboilers can be the most reliable means of heat input into a distillation, stripping, or absorption tower. They have no moving parts requiring maintenance or mechanical seals that leak. Properly designed, they can be used across a wide range of process conditions. However, application experience with them has led many plants, and occasionally entire industries, to avoid using thermosyphons. This is unfortunate, since often a low-cost alternative for a reboiler may be unjustly eliminated. This article covers some of the major design and operating requirements for thermosyphon reboiler systems. For example, the nature of the pressure balance loop and the interaction between fluid flow and heat transfer make designing thermosyphons more difficult. The engineer must pay attention to more details and understand both the static design of the system and the potential dynamic behaviors.