Simulation Of Optimizing The Study Of Inerting Plan Of The LNG Carrier's Cargo Tank

Because the situation of oil resource depletion is grim,natural gas as one of the three major energy is more and more favored by industrial areas.Due to the uneven distribution of natural gas energy in the world,30%of the world' s trading volume is transported by marine LNG carriers.Natural gas itself is flammable,explosive,so the security problem is particularly important in the transportation of LNG cargo process,especially in the process of adding.At present,the main methods to prevent liquid cargo tank explosion is that the internal oxygen concentration of liquid cargo tank is reduced,for example,the air in the liquid cargo tank and line is removed by the inert gas to reduce the oxygen concentration to the certain degree without combustion.That liquid cargo tank inerting effect is good or bad will directly affect the results of the whole process of inerting,such as oxygen concentration and the time required.So the direct factor for liquid cargo tank inerting effect is the distribution of inerting flow field inside the liquid cargo tank.Therefore,the main content is that the influencing factors of liquid tank internal flow field change are determined through the analysis of flow field of liquid tank inerting,finally the different inerting schemes are put forward according to the requirements of the different working condition.Firstly,consult and comb the domestic and foreign literature about inerting research,grasp the relevant theoretical knowledge and understand the latest development and research significance,introduce the composition of inert gas system on LNG carriers and inerting standard rules form classification society or maritimeAfter that,introduce the structure of cargo tank and Fluent,and use Fluent to simulate cargo tank inerting model,and prove accuracy of the model.Then put forward a few standards of juding cargo tank inerting effect and finally finds the volume-weighted average of the oxygen density can reflect the variation of 02 concentration in the cargo tank.Then,by summarizing the previous research,put forward a four inerting plans,and analyze factors that affect those four plans.If wanting the shortest time,advising completely mixed replacement plan.If wanting nitrogen volume is the least,advising vacuum replacement plan If both considering electricity consuming and nitrogen volume consuming,advising pressured-vacuum plan.However,never chose to pressured replacement plan alone.Finally,based on the inerting plan of cargo tank,optimize it in three aspects such as inerting gas inlet speed,cargo tank outlet pressure,and displacement of inlet and outlet positions.In a conclusion,the faster the inlet speed,the less outlet pressure,and the more vortex in the cargo tank,the better the inerting effect.So two optimum plan are achieved,one takes the shorted time,the other one takes the least amount of inerting gas and electric power.