LNG接收站内BOG再冷凝工艺的计算与优化

Calculation and optimization of BOG recondensation process in LNG receiving terminal

液化天然气(LNG)的储存过程中往往产生大量蒸发气体(boiled off gas,BOG),而LNG接收站内传统BOG再冷凝回收工艺具有能耗高、工况适应性差等缺点。基于ASPEN HYSYS软件对传统BOG再冷凝工艺进行建模,确定了影响能耗和质量比的3个主要因素:BOG处理量、压缩机和低压泵出口温度、外输压力,分析了3个主要因素对BOG再冷凝系统的影响规律,在传统BOG再冷凝工艺的基础上提出预冷式BOG再冷凝工艺,并对LNG接收站进行了最小外输工况的分析。模拟结果表明:在相同工况下,预冷式BOG再冷凝工艺较传统工艺节能效果显著,质量比和最小外输量均有明显下降。

The storage process of liquefied natural gas(LNG)often produces a large amount of boiled off gas(BOG),while the traditional BOG recondensation recovery process in the LNG receiving terminal has the disadvantages of high energy consumption and poor adaptability to working conditions.Based on ASPEN HYSYS software,the traditional BOG recondensation process is modeled,and three main factors affecting energy consumption and mass ratio are determined:BOG throughput capacity,outlet temperature of compressor and low-pressure pump,and transmission pressure.The influence laws of the three main factors on the BOG recondensation system are analyzed.Based on the traditional BOG recondensation process,the pre-cooling BOG recondensation process is proposed,and the minimum outward transmission conditions of LNG terminal are analyzed.The simulation results show that under the same conditions,the energy-saving effect of pre-cooling BOG recondensation process is significant compared with the traditional process,and the mass ratio and minimum output are significantly reduced.