| As we know, human beings are suffering a serious challenge about living environment.Coal and oil are still main source, though the combustion of them produces large amount of harmful gas. Liquefied Natural Gas is believed to be the clearest energy. However, it is not good time yet for large ship to use LNG as the single fuel after considering economy.Therefore, the dual fuel system can be a transitional choice. SPB (self-supporting,prismatic-ship,IMO type B) tank is seemed to be the fittest structure to store this kind of fuel.Main contents of this paper are to design a large type B tank and to check it. Target ship is 398k DWT bulk carrier, the volume of SPB tank is 12500m3. This paper is to present and analysis questions encountered during the process, referring to DNV rules and other related data.Four main aspects in this study are listed as follows:(1) Different types of containers are compared and advantage and disadvantage of them are shown. Structure and plan such as swash bulkhead, insulation and supports are designed referring to the feature of type B tank. The method is to find the key relation between each design and performance of the fuel tank.(2) A research about thermal distribution in the fuel tank is carried on based on related data. Thermal distribution at any filling level is given through a simplified method.Temperature of inner shell of the bulk carrier is estimated using one-dimension thermal conduction model.(3) Learn Dytran and motion characteristic of liquid. Natural periods of liquid motions in the tank are estimated based on empirical formula and Dytran, respectively.(4) Some questions about strength assessment of the tank are analyzed referring to DNV classification. A method to calculate drought for ultimate static state based on Patran is provided. This paper gives result of a typical load condition based on design wave method. A simply but conservative transformation is given based on Paris' formula. |
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