A major southeastern U.S. refinery processes 250,000 bpd of crude oil. The total hydrocarbon liquid stream sent from the FCC unit to the de-ethanizer stripper is 192,000 bpd. Approximately 60,000 bpd is processed from this stream to produce a final gasoline product.

Water in the hydrocarbon feed from the FCC unit was causing internal hydrogen blistering and corrosion of the de-ethanizer stripper tower. The severity of the problem was such that vessel rupture could become a concern if immediate corrective measures were not taken to eliminate the wall loss. The stripper operates at over 300 psig and 105°F. Several technologies were evaluated to solve the problem, including salt beds, coalescers, and gravity separators.

After successful on-site testing was performed and economics were evaluated, the operator installed Pall Corporation's AquaSep Liquid/Liquid Coalescing system. Pall Corporation's filter and coalescer assemblies are designed to handle 192,000 bpd of de-ethanizer feed under normal operating conditions. The AquaSep Liquid/Liquid Coalescer system consists of a pre-filter assembly equipped with Pall Ultipor® filter elements followed by a vertical AquaSep Liquid/Liquid Coalescer unit.

Blistering and internal corrosion of the de-ethanizer vessel was significantly reduced following installation of the AquaSep Liquid/Liquid Coalescer unit. The stripper corrosion is now well within pressure vessel safety design requirements. An additional benefit has been improved fractionation by the stripper. Pall Corporation's prefilters only require changeout approximately every 4 months while the original coalescer elements have been in service since start-up over two years ago.