FRI Studies on Kettle Reboiler Hydraulics and Distillation Diagnostics

Excessive pressure drops caused by liquid entrainment in kettle reboiler operations are often associated with problems encountered in distillation columns. These issues can be difficult to diagnose, because information and data regarding kettle hydraulics and entrainment are generally lacking.  One of the two industrial-size kettle reboilers at Fractionation Research, Inc’s (FRI’s) experimental distillation unit was equipped with four large observation windows that were strategically positioned for hydraulic studies. 

Hydraulic studies on the kettle reboiler conducted by FRI will be discussed, including visual observations, pressure drop and entrainment data obtained from this kettle reboiler with different hydrocarbon systems. Entrainment data were also collected using gamma scanning of the kettle’s vapor return line at various heat fluxes.  Pressure drop data were compared against entrainment measurements and visual observations, and predictions using literature correlations.  Reasonable agreement was found between the measured data and the predicted values, until the onset of visible entrainment from the kettle.