A Study on the Sloshing Risk Reduction in Membrane-type LNG Tanks by Interchanging Liquid Cargo between Tanks

摘要

Floating Liquefied Natural Gas Production, Storage and OffloadingUnit (FLNG) and Floating Storage and Regasification Unit (FSRU)have appeared in the offshore LNG chain recently. Large scalemembrane tanks are expected to be used in some such facilities;however, special attention should be paid to half-loading in themembrane tanks because of the risk of sloshing. A distribution controlmethod by which LNG is distributed and interchanged between thetanks to reduce the sloshing risk was proposed by Yokohama NationalUniversity. In this operation, the sloshing risk is reduced by shorteningthe period spent in the half-load condition as much as possible. In thisstudy, the operation was optimized using a genetic algorithm. Severalcases involving different charging operations were examined, and theflexibility of this method was demonstrated. It was shown that aconsiderable decrease of the sloshing risk is achieved.