REVAMPING THE EXTRACTION BLOCKS IN VACUUM RESID DEASPHALTING UNITS

0009-3092/07/4301–0017 © 2007 Springer Science+Business Media, Inc. Deasphalting of vacuum resid with liquefied propane is usually conducted in extraction towers of the gravity type. Standard towers (Fig. 1a) have a small (~7 m) height of the propane and vacuum resid reaction zone and are equipped with baffle trays that consist of metal trays 353 mm wide and 6 mm thick with a step of 68 mm positioned at a 45° angle. This design of the internals insignificantly increases the time the phases are held in the tower and causes formation of “coke” deposits, which are high-melting asphaltite, on the trays. The extraction tower with baffle trays is close to the spray tower in efficiency.