Gasketed and all-welded heat exchanger units have been supplied for offshore crude oil processing duties on the Marlim Sul FPSO by Tranter PHE. The units were designed, manufactured, and delivered to the customer to meet a demanding schedule, with the first units shipped just four months from receipt of order. The Tranter PHE gasketed heat exchangers and UltraMax all-welded unit are to be installed in the crude oil processing system on the Petrobras-operated FPSO. The UltraMax unit was supplied to condense steam from the boiler, used to heat water circulated in the internal heating medium circuit. FPSOs have traditionally employed shell and tube heat exchangers for these duties, as gasketed designs proved unsuitable for the high temperatures involved. However, shell and tube exchangers are bulkier, and have a heat transfer co-efficient 4 or 5 times lower than plate heat exchangers. Tranter’s patented UltraMax all-welded units combine the high efficiency of a plate heat exchanger with a safe gasket-free design, and offer the added advantages of compact size, low weight, and a rapid response to desired process changes. Duties for the gasketed plate heat exchangers include heating the crude oil to a suitable temperature prior to entering the oil/water separator, cooling the crude oil before storage, cooling the water which is separated from the crude oil before discharge at sea, and cooling of the internal fresh water cooling medium circuit by seawater.
The gasketed units for heating the crude oil are specially designed, taking two-phase flow characteristics into account. Due to the high chloride content of the seawater and oil, all gasketed PHEs were specified with titanium plates to resist corrosion.
