Research On Thermal Insulation Material And Insulation System Of New Independent Type B LNG Carrier Tank

Liquefied Natural Gas(LNG)carrier is the main transportation tool for international LNG trade.LNG carrier is characterized by many highlighted features such as high technology,high challenge and high added-value.There are few shipyards capable of building large-scale LNG carrier in China at present.However,most of core technologies and patents are possessed by some foreign companies.It is of great significance and value to research and develop new type LNG carrier,which can enhance profitability and competition capacity of Chinese ship manufacturing industry.In this paper,the thermal insulation material and insulation system of a new independent type B LNG carrier with the total capacity of 172000m~3,which was lately developed by Hudong-Zhonghua Shipbuilding(Group)Co.,Ltd,were studied.(1)The thermal insulation performance of the new reinforced polyurethane foam(RPUF)was tested in laboratory.The thermal conductivity of RPUF material was tested by using a guarded hot plate(GHP)apparatus under cryogenic condition.(2)Based on the analyses of the cargo containment system structures,by taking into account of some reasonable and necessary simplification,the heat transfer model of the containment system was established.An analytical method and ANSYS Fluent software were used to calculate the boil off rate(BOR)of LNG cargo under different working conditions with different thickness of insulation layer.(3)The thermal insulation system of the new LNG carrier was designed.The assembling method of prefabricated polyurethane foam panels was standardized and modularized.A 1:1 prototype of standard module of the insulation system was built in laboratory and the mock up test was conducted for actual cargo tank insulation structure of modular installation process.The following conclusions and achievements were obtained:(1)The thermal conductivity of RPUF material is within the interval of 0.0118W/m?K to 0.027W/m?K,which can meet the insulation performance requirement.(2)The thickness of insulation layer should be not less than 400mm,in order to meet the requirement that the boil off rate of LNG cargo is less than 0.1%per day.(3)The new insulation system of the new LNG carrier has many advantages such as easy installation,easy maintenance and high reliability.This type of cargo containment system has a promising application prospect in future.