液化天然气船货舱内部压力研究

Research on the Internal Pressure of LNG Carrier Cargo Tank

LNG船的货舱内部压力应按照IGC规则的要求进行计算。其中,无因次加速度合成方法和横稳心高(GM值)是影响货舱内部压力的重要因素。IGC规则允许采用2种方法来进行无因次加速度的合成:二维加速度椭圆合成法和三维加速度椭球合成法。针对某22万m3薄膜型LNG船,编制了载荷计算电子表格,比较了这2种加速度合成方法导致的货舱内部压力的差异,电子表格计算结果与船级社相应计算软件的结果相一致。另外,就GM值对货舱内部压力的影响进行了讨论。

The internal pressure of LNG carrier＇s cargo tank should be calculated according to IGC code,where composition of the non-dimensional acceleration components and calculation of the metacentric height （GM） are the key factors to influence the internal pressure of cargo tank.ICG codes allow two methods to compose the non-dimensional acceleration：2D acceleration ellipses and 3D acceleration ellipsoids.Load calculation spreadsheet is programmed for a 220,000 m3 membrane LNG carrier to study the difference of resulting internal pressure by the two methods;same calculation results are obtained using the spreadsheet as according to the classification regulations.In addition,the effect of GM on cargo tank internal pressure is discussed.