LNG接收站蒸发气(BOG)增压再液化技术路线选择及条件限制

Route selection and condition limitation of technologies of boil-off gas(BOG)pressurization and reliquefaction in LNG terminal

部分液化天然气(LNG)接收站在投运初期无外输管网,蒸发气(BOG)只能通过增压后再液化的方式进行回收,目前主要有3种再液化工艺。为了解决再液化工艺领域存在的问题,以两种增压选型方案和3种再液化制冷路线为基础组合成6种可能方案,根据某LNG接收站的实际数据,从工艺流程、操作性能、技术垄断性、能耗及投资等方面对各方案进行了对比分析,并按该站再液化单元运行年限要求进行了投资-运行总费用比较,由此确定采用第一级可耐低温的BOG增压机的混合冷剂制冷再液化工艺流程方案。然后,收集并给出了国内接收站已投运的BOG再液化回收装置情况统计表,进一步验证了混合冷剂制冷再液化工艺流程占主导的分析。最后,结合以往项目经验,介绍了再液化工艺设计中受接收站约束的限制条件。所研究结论可为后来设计者提供重要的思路和参考。

Some liquefied natural gas(LNG)terminals have no export pipeline network in the initial stage of operation,so boil-off gas(BOG)can only be recovered by pressurization and reliquefaction.At present,there are three main reliquefaction processes.To solve the problems existing in the field of the reliquefaction process,six possible schemes were combined based on two pressurization schemes and three reliquefaction refrigeration routes.Combined with the actual data of a LNG terminal,the schemes were compared and analyzed from the aspects of process complexity,operation performance,technological monopoly,energy consumption and investment.According to the operation life requirements of the station's reliquefaction unit,the comparison of investment-operating total cost was carried out,and thus the mixed refrigerant refrigeration and reliquefaction process with the first stage BOG booster which can resist low temperature is determined to be the best scheme.Then,the statistical table of BOG reliquefaction recovery unit which has been put into operation in domestic terminal was also collected and given,and the analysis that the mixed refrigerant refrigeration and reliquefaction process occupies the mainstream status is further verified.Finally,combined with the experiences of previous projects,the constraints of receiving station in the process design of reliquefaction were introduced.The research conclusions can provide important ideas and references for later designers.