Troubleshooting the Diameter Transition Zone of a Depropanizer Tower

A depropanizer tower with a large diameter top section and smaller diameter bottom section was field tested and studied for its root cause of flooding. In the diameter transition zone, a two-phase feed was being introduced. Gamma scans indentified that the trays in the top section were flooding and the liquid accumulation initiated in the transition zone. A neutron backscatter technique was used to investigate downcomer hydraulics and identify the root-cause of flooding in the top section of the column. Coupled with the field troubleshooting and a careful analysis of the design showed likely causes of the flooding problem. Recommendations for modifications were made and installed.