国内外学者提出过许多关于液化天然气(liquefied natural gas,LNG)接收站蒸发气(boil-off gas,BOG)再冷凝工艺的优化方案。其中,采用预冷法对再冷凝工艺进行优化的方案由于前期投入较少且优化效果明显,更具有现实意义。然而,现有的预冷法优化方案还存在着优化原则不清晰和考虑工况不全面等问题。本文介绍了LNG接收站现有BOG再冷凝工艺流程与经预冷法优化后的再冷凝工艺流程,分析得到了预冷法优化的理论原理。针对接收站两种典型工况提出了相应的优化原则。以江苏如东LNG接收站现有再冷凝工艺流程为计算实例,运用HYSYS软件对优化前后的再冷凝工艺进行模型建立与流程模拟,应用所建模型对优化前后的再冷凝工艺总功耗进行对比分析。结果表明:经改进后的再冷凝工艺预冷法优化方案可以有效地根据相应的优化原则对两种典型工况进行优化。通过将研究成果应用于江苏如东LNG接收站可知,在两种典型工况下,优化后的BOG再冷凝工艺较原工艺分别节约系统总功耗9.8%和21.5%。
Domestic and foreign scholars have proposed many optimization schemes for the recondensation process of boil-off gas(BOG) in liquefied natural gas(LNG) terminals. The pre-cooling optimization scheme has more practical significance because of less initial investment and obvious optimization effect. However, the existing pre-cooling optimization scheme has problems such as unclear optimization principles and incomplete consideration of working conditions. Therefore, this paper introduced the existing re-condensation process in LNG terminals and the process optimized by precooling method. The theoretical principle of the pre-cooling optimization method was obtained and corresponding optimization principles for two typical operating conditions in LNG terminals were proposed. The existing recondensation process of Rudong LNG terminal in Jiangsu province was used as an example. The models were established and the recondensation process was simulated before and after optimization using HYSYS. A comparative analysis of the total power-consumption of the recondensation process before and after optimization was carried out using the built-in model built in HYSYS. The result showed that the improved pre-cooling optimization scheme can effectively optimize the two typical working conditions according to the corresponding optimization principle. The application of the research results at the Rudong LNG terminal in Jiangsu indicated that the improved pre-cooling optimization scheme resulted in 9.8% and 21.5% energy reduction, respectively, under the two typical operating conditions.
Chemical Industry and Engineering Progress