Desigh Of FLNG Tank Type Based On Analysis Of Sloshing Load

With the development of offshore oil and gas resources mining technology, Floating LNG ship becomes hotspot of research, and LNG tank is one of the key equipments of FLNG ship. From LNG transportation ship to floating LNG ship, sloshing problem becomes more and more serious as the tank’s volume significantly increases. Because FLNG ship can not avoid extreme sea conditions, as it must stay at one place for a long time, with the occasional occurrence of partial filing condition, sloshing load becomes one of the key issues in FLNG tank design.In the same excitation condition, the severity of sloshing in the tank has a big relationship with tank’s shape, tank’s dimensions and filling level. Proper tank shape can restrain the motion of liquid, mitigate the impact to tank wall, proper size of tank can make the free surface of the liquid away from the natural frequency of free surface, which can avoid the resonance. This paper focuses on FLNG tank, aims at solving the key issue--sloshing load, carrying out tank shape design and tank size optimization mainly with numerical methods. The FLUENT software is used for numerical simulation, based on finite volume method, and verify the validity of the numerical method by comparing with two sets of tank model sloshing experiments. Tank shape design begin with the basic shape--cuboid, change the corner type and corner position to transform the basic shape into several typical shape. Carry out an assessment of sloshing loads for shape factor and tank shape by numerical simulations to determine the optimum shape of the tank. Based on the full-size tank simulation in real sea condition, contrast the sloshing phenomenon and impact load between membrane tank and new tank shape, confirm that the shape this paper proposes is reasonable. Size optimization mainly aims at membrane tank in which sloshing issue is serious, estimate the order of sloshing load by simulation of full-size tank in real sea condition, find out the dangerous filling level and research the relationship between tank size and sloshing load, ultimately determine the proper range of tank size and the optimal size.