Rapid Evaluation of FCC Main Fractionator using HYSYS Column Analyzer

Elliott Robertson

Burns & McDonnell

This paper summarizes rapid evaluation of an existing FCC Main Fractionator using HYSYS Column Analyzer. A HYSYS V9 model was developed for the Main Frac and was tuned against test run data at maximum stable operating rates. The Main Frac was known to flood at a certain feed and LCO sidedraw rates. Gamma scans indicated flooding in the LCO draw section, and HYSYS Column Analyzer was used to confirm these results. Replacing trays in the existing Main Frac with packing for pressure drop reduction did not alleviate tower flooding, as shown by Column Analyzer. Reduction of steam and slurry rates to minimum levels did not alleviate flooding. A replacement tower diameter was determined with HYSYS Column Analyzer in interactive sizing mode. A new tower would allow more separation stages allowing better LCO quality increasing product value which results in more favorable payback. HYSYS Column Analyzer was used to demonstrate operational flexibility with the new tower with respect to feed changes and seasonal effects.