Project Synopsis

Provide a process simulation of a crude hexachlorocyclopentadiene (Hex) purification tower and support troubleshooting efforts of this distillation column.

Project Summary


The client, a chemicals production company, contracted Process Engineering Associates, LLC (PROCESS) to complete a process simulation for their crude hexachlorocyclopentadiene (Hex) purification tower.  Over time, the performance of the column had declined resulting in increased waste generation.  Additionally, operating conditions within the tower had changed, presumably due to modifications in upstream units.  PROCESS was asked to create a model of the distillation train (using PROCESS' commercial computer process simulation software CHEMCAD) to support the plant’s troubleshooting and optimization efforts.

Prior to column simulation, analytical and process data were collected for the tower.  Due to variations in the data, PROCESS created distillation models based on three data sets.  For each data set, overall column efficiencies were adjusted to match the simulation output to the process data collected.  For comparative purposes, tower efficiencies were also calculated using empirical prediction methods.  Differences in the two efficiency estimates indicated the column was operating outside its hydraulic limits and/or had internal failures.

Based on findings from the distillation model, hydraulic loads were determined which indicated tray and downcomer flooding within the stripping section.  Historical tower scans were reviewed and revealed trays operating with moderate to high liquid levels. This, coupled with evidence of previous fouling issues, led updated tower scans to be ordered.   From these scans, two trays were determined to be operating with no liquid level, presumably due to collapse.  Furthermore, liquid levels on some trays were within one inch of the adjacent tray.  These findings supported the low efficiencies determined by the model.  Simulations performed, assuming a modest efficiency improvement afforded by the correction of these issues, indicated the column would be capable of approaching production goals with no significant change to historical operating conditions.

Industry Type

  • Chemicals Production

Utilized Skills

  • Distillation tower troubleshooting
  • Distillation system simulation

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