(133d) Troubleshoot of Column Containing Structured Packing

An ortho-xylene column in an aromatics plant in Taiwan was revamped. The goal was an increase in product recovery following a specification change in product purity. The revamp included the replacement of 80 trays with 4 beds of structured packing. Upon restart, the column performed below expectations. Data were collected at two different conditions. Those data included temperature profiles. Those conditions were well below the flood points. Analyses revealed that the stripping-section and the rectification-section performances both deteriorated at higher internal loadings. The source of the deteriorations was believed to be liquid and vapor maldistributions caused by overly-deep packing beds. The column was re-packed with the same packing in 6 shorter beds. The column is now achieving original design targets.