预冷式-二级压缩BOG再冷凝工艺研究

Study on the Pre-Cooling Two Stage Compression BOG Recondensing Process

针对国内某一LNG接收站再冷凝工艺存在能耗大、回收率低、稳定性差等问题,提出了预冷式-二级压缩BOG再冷凝工艺:利用高压泵出口LNG预冷一级压缩机出口BOG,降低工艺物料比;通过二级压缩减小压缩机进出口BOG比焓差,降低压缩机能耗;新增再冷凝器和稳压泵,利于减小高压泵运行波动。使用ASPEN-HYSYS模拟接收站再冷凝工艺流程,以该接收站典型工况BOG产量7640 kg/h,LNG外输量180 t/h为例,新工艺节能8.26%,并且随着BOG产量增加,节能效果上升,最大节能14.04%。新工艺提高了接收站经济性和安全性,为再冷凝工艺选择提供参考。

The recondensing process of a certain LNG receiving terminal in China has issues such as high energy consumption,low recovery rate and poor stability.This paper proposes a pre-cooling two stage compression BOG recondensing process,which utilizes LNG from the high pressure pump to pre-cool BOG from the primary compressor for reducing the process material ratio,and reduces the BOG ratio enthalpy difference of the compressor inlet and outlet through the secondary compression for reducing the compressor energy consumption,and adds the new condenser and the constant pressure pump,which is beneficial to reduce the fluctuation of high pressure pump operation.ASPEN-HYSYS is used to simulate the existing process flow of the receiving station.Under the condition of BOG output of 7640 kg/h and LNG external output of 180 t/h,the new recondensing process can save energy by 8.26%.With the increase of BOG output,the energy saving effect is more obvious,with the maximum energy saving up to 14.04%.The new process improves the economics and safety of the receiving station and provides a reference for the recondensing process selection.