Interrelationships of LNG cargo containment systems and machinery configurations on LNG carrier - design and operational factors with economic assessment
摘要
The main objective of this project has been to design a ship for LNG trade between Port Moresby and Singapore, with a cargo capacity corresponding to a total freight work in the range of 1.000,000 - 800,000m3 annually. The main design emphases have been on propulsion- and cargo handling systems. \nThe project is divided in to three parts. The first part gives a thorough investigation into design theory and design optimization methods. The second part gives description of current state of the art within LNG carrier designs and technical interrelationships in ship design. The third part contains the ship design process, following the systematic approach illustrated below.\n Based on a qualitative analysis of the most promising containment systems offered in the market, LNT A-BOX was found favourable. The LNT A-BOX consists of an independent tank type A as primary barrier, with liquid tight thermal insulation connected to the hull compartment as secondary barrier, resulting in a fabrication friendly and cost effective design with access to both primary and secondary barrier for ease of inspection and repairs. \nThe insulation system is built up by two layers of insulation and can either consist solely of polyurethane foam, polyurethane panels or expanded polystyrene panels or a combination of these. No obvious benefits of each insulation material were clear, so six different insulation systems were determined for further investigations. \nBased on the given trade rout, a cargo capacity within the range of 35,500-49.000m3, divided in three equal sized cargo tanks, were found necessary to meet required annual freight work as well as damage stability requirements. The physical parameters of each cargo tank were furthermore determined by dimension ratios from previously built IMO A tanks in combination of with free board evaluations on existing gas carriers. A maximum allowable insulation thickness of 1040mm was set as constraint when determining required cargo hull compar