Abstract: With the Dalian liquefied natural gas (LNG) terminal as the example, the boil off gas (BOG) treatment process was analyzed using Aspen software. The combined operations of BOG re-condensation liquefaction and direct compression was proposed, as well as adding pre-cooling device in the re-condensing process . The analysis results show that if the receiving station can supply sufficient amount of LNG stably, the re-condensation process route will be chosen in priority, otherwise the system will be switched to the high-pressure compression process line automatically, and transported LNG to the pipe network directly. In this way, it can resolve the energy waste problem caused by the BOG release due to excess pressure in the tanks and pipelines. In the re-condensation process with the pre-cooling device, 37.4% energy consumption can be saved compared with the one without.

Key words: liquefied natural gas (LNG), boil off gas (BOG), re-condensed, direct compression, pre-cooling

摘要： 以大连液化天然气(LNG)接收站为例,利用Aspen软件对LNG接收站蒸发气(BOG)处理工艺流程进行分析。提出了BOG再冷凝液化与直接压缩混合使用的运行方案,并且在再冷凝工艺流程中增加预冷装置。分析结果表明:当接收站能够稳定提供足够量LNG时,系统优先选择再冷凝工艺路线,否则自动切换至高压压缩工艺路线,并直接输送至管网。该混合使用方案能够解决因储罐及管网内BOG压力过高而放空所造成的能源浪费问题。再冷凝工艺流程中,加装预冷装置之后,压缩机较加装之前节约能耗37.4%。

关键词: 液化天然气, 蒸发气, 再冷凝, 直接压缩, 预冷