LNG接收站卸料管道保冷层厚度优化模拟

国内LNG接收站卸料管道保冷层多为组合式保冷,保冷层普遍存在着材料浪费的问题。为此,应用Ansys Workbench(AWE)工作平台分别建立了LNG接收站典型的外径为40 in、10 in(1 in=25.4 mm)卸料管道保冷层传热及优化模型。在满足使用要求及设计标准的前提下,对保冷层组合厚度进行优化模拟,并分析了保冷材料热导率受温度变化影响时,其对管道保冷性能的影响。结果表明:优化后,40 in管道每1 000 m可节省投资156万元,10 in管道每1 000 m可节省投资25.62万元;在设计时,如不考虑保冷层热导率随温度变化而采用平均热导率计算,保冷层厚度设计偏保守。对组合保冷材料交接点处温度及各类输入参数敏感性进行分析后得出结论:优化后管道各类指标性能均满足使用要求;内层保冷材料厚度对总投资及热流密度影响最大,大气温度对交接点处温度影响最大。该优化模拟结果及基于AWE工作平台流程化设计优化方法可为LNG管道保冷设计提供参考。

The optimization simulation of insulator thickness in LNG unloading pipelines

Materials waste widely exists in the design of domestic insulation layers of unloading pipes in LNG terminals, which are usually constructed with combined insulators. The Ansys Workbench working platform (AWE) was used to establish a heat-transfer and optimization model of the unloading pipes with typical sizes of 10 and 40 inches in diameter. Optimization simulation was performed on the insulator thickness and the insulation properties, which are effected by varying conductivity on the premise of meeting the operating requirements and confirming to the design standards. The result shows that 1 560 thousand Yuan (RMB) was saved for every 1 km-length pipe with 40 inches in diameter and 256.2 thousand Yuan was saved for that with 10 inches in diameter. The design of the insulator thickness is conservative without considering insulators conductivity variation with temperatures, so the average heat conductivity should be calculated in the design. The analysis of the temperature at the joint points at the insulation layers and all kinds of parameter sensitivity also demonstrates that the performance indicators of pipeline can satisfy the operating requirements after optimization, and among all the researched factors, the thickness of inner-insulators has the greatest impact on the total investment and heat flux, and the atmosphere temperature has the greatest influence on the junction point of insulators. Therefore, the optimized conclusions and the optimal design method based on the AWE work platform provide references for the insulation layer design in LNG pipelines.