小型LNG船C型独立液舱内部压力计算

The Internal Pressure Calculation of Type C Independent Tanks of Miniature LNG Carrier

根据IMO《国际散装运输液化气体船舶构造与设备规则》及相关的压力容器标准GB 150.3-2011,提出一种针对小型LNG船C型独立液舱内部压力的三维计算方法,并借助AutoCAD的建模与计算功能,利用VBA进行二次开发,用程序实现内部压力及板厚的三维计算。针对某多用途小型LNG船的C型独立液舱,分别采用三维计算方法与传统的二维计算方法进行计算并比较结果差异,同时分析由船舶运动引起的加速度对计算结果的影响。结果显示:采用三维计算方法所得结果更准确,在精确设计时有必要按照三维计算方法进行计算;在工程实际中,针对设计蒸气压力通常大于0.3 MPa的单圆筒C型独立液舱的内部压力计算,可以采用传统的二维方法;由船舶运动引起的加速度对计算结果的影响不可忽略;对于设计蒸气压力较小的其它形式液舱的内部压力计算,应采用三维计算方法。

According to IMO“International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk”and the relevant regulations for pressure containers,“GB150.3-2011”, a 3-di-mensional method for the calculation of internal pressure of Type C independent tanks of miniature LNG carrier is given in this paper. With the assistance of the modeling and calculating function of AutoCAD, the VBA secondary development is used to achieve the 3-dimensional calculational of the internal pressure and thickness of plates. Also, the internal pressure of a Type C independent tank is calculated with both the 3-dimensional method and traditional 2-dimensional method separately, and the obtained results are com-pared carefully. Meanwhile, the influence of the acceleration caused by ship motion on the results is ana-lyzed. It is shown that the 3-dimensional method yields more accurate results and it is preferable in the pre-cision design. However, in real projects, the traditional 2-dimensional method is also applicable in the in-ternal pressure calculation of single-cylinder Type C independent tanks of a design steam pressure over 0.3 MPa in general, and the influence of the acceleration caused by ship motion cannot be ignored. The 3-dimensional method should be taken for the internal pressure calculation in the tanks of other types in lower design steam pressure.