The Mexilhão Project entered the final assembly phase of the gas processing modules with the arrival in July of the MEG (Mono Ethylene Glycol) Recovery module, supplied by Cameron-Petreco Process Systems to Estaleiro Mauá SA, a company contracted by Petrobras for the construction from the Mexilhão platform.
The first to be supplied to Petrobras, and the first also to Brazil, Petreco's MEG recovery module weighs around 585 tons and has dimensions of 20m x 12.4m x 20m (length x width x height). The module was transported from Singapore to the Mauá Shipyard in Niterói, for final coupling to the main gas processing module.
The module recovers the MEG used in countercurrent as a hydrate inhibitor and absorber of impurities and salts contained in the gas stream, which then returns to the system for reuse. The MEG recovery process comprises four steps: pre-treatment of rich MEG (fluid preheating and MEG cooling), vaporization, vacuum distillation and removal of salt and other impurities.
The plant that composes this module causes the MEG contaminated with salts and other impurities to flow into the separator vessel (flash) which, operating under vacuum, enables instantaneous vaporization when mixed with the “mother liquor”, which is recycled and heated. . The vaporized fluid, when leaving the vessel, leaves behind the solid residues that were in suspension and/or dissolved when in the liquid phase.
The recycled liquid is taken from the separator's internal reservoir, and as the boiling point of MEG is higher than that of water, it will result in less water volume. Then, the MEG is subjected to sensible heat between 10 and 20 ºC, in order to avoid thermal degradation and in order to promote its complete vaporization, and finally it passes through a distillation column to recover the clean and free glycol reconcentrate. of salt. The module will have the following performance:
This MEG recovery will provide Petrobras with significant savings in its operating costs, since the rich MEG will no longer need to be discarded due to contamination. On platforms that do not have this recovery plant, the MEG, when not replaced from time to time, can cause severe damage (corrosion) to the platforms' gas processing equipment and also to the subsea pipelines that connect these platforms to the onshore facilities that process and treat this gas.
Currently, four other MEG Recovery modules are being built by Cameron - Petreco in Singapore, two of which will be used in FPSOs leased by Petrobras.