BK1-16 Boiling Temperature Rise due to Recirculation in Kettle Reboiler
Recirculation in kettle reboilers causes a boiling temperature increase or rise for mixtures because it increases the concentration of less volatile components of the bundle flow. Methods in Xist® 9.0 account for this rise at the top of the bundle. However, the bubble point calculation is based on the feed composition unless the liquid inlet temperature at the bundle entrance becomes higher than the feed bubble point. A new method calculates the bubble point temperature rise based on the recirculation ratio. This method more accurately calculates the local mean temperature difference for cases with subcooled liquid at the inlet. It does not impact cases with saturated liquid at the inlet.