关键词: 液化天然气, 蒸发气, 再冷凝, 直接压缩, 预冷

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