Design Development of FSRU from LNG Carrier and FPSO Construction Experiences

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Abstract With the expansion of natural gas demands in many countries, the necessity of LNG receiving terminals has been increased. The offshore LNG Floating Storage and Regasification Unit (FSRU) attracts attentions not only for a land based LNG receiving terminal alternative, but also for a feasible and economic solution. Nowadays, as the reliability of offshore oil and gas floating facilities and LNG carriers gains with proven worldwide operations, the FSRU can achieve a safety level that can be comparable to an onshore terminal. The design development related with safety features of the FSRU has been extensively carried out by oil and gas companies, shipyards, engineering companies, and equipment vendors, and has been successful so far in many fields. The construction of the FSRU can be achieved by integrating various technologies and experiences from many disciplines and many participating companies and vendors. In this paper, reviews on some of the important design features and design improvements on FSRU together with the practical construction aspects in cargo containment, vaporization system, ESD system, and operation modes, have been covered in comparison with actual LNG carrier, onshore receiving terminal, and FPSO systems. In order to materialize an FSRU project, the technical and economic justification has to be preceded. It is believed that once the safety and technical soundness is convinced, the FSRU can bring a higher project feasibility by reducing the overall construction time and cost. Through this study, an FSRU design readily applicable to an actual project has been developed by incorporating experiences gained from many marine and offshore projects. The wide use of proven standard technologies adopted in the series construction of LNG carriers and offshore FPSOs will bring the project efficiency and reliability. Introduction Onshore based LNG receiving terminal technologies are quite mature, and have been proved their reliabilities through decades of operation. At the same time, offshore based platform and Floating Production Storage and Offloading (FPSO) technologies have been developed significantly for these 20 years. Moreover, the steel hull based LNG storage tanks have proved their economy and reliability through many years of LNG carrier operation. The proven technologies from different sectors naturally brought the idea of the offshore LNG Floating Storage and Regasification Unit (FSRU). By combining the related technologies, a safe, reliable, and economic LNG FSRU may be considered as an alternative of the onshore LNG receiving terminal. As the case of the FPSO, the FSRU technology development has also been led independently and jointly by esteemed oil and gas companies, offshore equipment vendors such as turret mooring and offloading system suppliers, engineering companies, and shipyards. Each party's dedication and intensive development effort for the offshore application made the LNG FSRU realization more feasible. However, in actual LNG FSRU application, there are still many areas to overcome in basic cargo tank arrangement, cargo unloading from an LNG