Study On Probability Of Tank Rupture For LNG Fueled Ships And LNG Container Carriers

With the increasingly strict emission requirement of exhaust gas from ships both domestic and abroad,natural gas has become an alternative fuel for ships of various types.In recent years,LNG fueled ships developed rapidly.However,due to the inflammable and explosive characteristics of natural gas,inland LNG fueled ships is slow in advance in China.LNG carriers are managed as dangerous cargo vessels currently.As for LNG fueled ships,because the lack of related research about their safety,maritime administration has not issued relevant management measures.In order to quantitatively compare the safety of LNG fueled ships and LNG carriers,the finite element analysis software,ANSYS,is used to simulate the collision process of both LNG fueled ships and LNG carriers.Through a series of calculation examples,the stress and strain distribution contours of LNG fueled ships and LNG carriers of different scales are obtained when they are impacted by ships of different tonnages.The critical energies of LNG fueled ships and LNG carriers are calculated.And the formula for calculating the critical energy of different kinds of ships are interpolated from the critical energies.According to the actual ship traffic data of the Yangtze River,the calculation program based on Monte Carlo method was designed to calculate the rupture probability of LNG storage tanks in the midstream and downstream LNG fueled ships and LNG carrier in the Yangtze River trunk line.The influencing factors of the rupture probability during the collision are explored.Through the research in this paper,it is found that LNG carriers have larger probability of tank damage than LNG fueled ships,but the tank failure probabilities of the two LNG fueled ships selected in this paper are not much different.The ship speed of striking ships is an important factor affecting the probability of tank damage.Therefore,the consequences that ships are struck by downwards vessels in downstream are the most serious.But the velocity of struck ship influences the tank rupture probability not so obviously.In this paper,the damage probability of the tank under different angles of collision is calculated.The results show that the damage probability of the tank is larger when the collision angle is close to 90°.The data calculated in this paper has certain reference significance for quantitative evaluation of the safety of LNG fueled ships and LNG carriers,and provides a theoretical basis for the issue of relevant management measures for maritime authorities.