限制空间氮气置换过程分析与优化

Analysis and Optimization of Gas Replacement in Limited Space

为提升LNG船液舱气体置换作业效率,对置换过程进行数值分析及优化。基于CFD数值仿真方法,对氮气置换限制空间内空气的过程进行仿真和分析,研究进口面积、形状和流速对置换过程的影响。通过改变进气速度和进气方式进行多组数值模拟并得出优化方案。结果表明:进气口直径越大越容易实现推移式置换;当进气口形状设计为矩形嵌套时,空间内可形成推移式置换,与直接置换相比最多可减少约11.21%的氮气量、缩短17%的置换时间,更具有经济性,对指导LNG液舱实际置换作业具有工程意义。

In order to improve the gas displacement efficiency of LNG ship tank, the displacement process is numerically analyzed and optimized. Based on CFD numerical simulation method, the process of nitrogen displacement in limited space is simulated and analyzed, and the influence of inlet area, shape and flow rate on the displacement process is explored. By changing the intake speed and intake mode, a number of numerical simulations are carried out and the optimization scheme is obtained. The results show that the larger the diameter of the intake port is, the easier it is to realize the push displacement. When the shape of the intake port is rectangularly nested, it can reduce the nitrogen volume by 11.21% and the replacement time by 17% at most compared with the direct replacement, which is more economical, and has engineering significance for guiding the actual replacement operation of LNG tank.