LNG接收站BOG联合处理运行方案优化

Optimization of operation scheme with combined BOG treatment process in LNG terminals

中石油唐山LNG接收站同时存在再冷凝与高压压缩外输两种BOG处理工艺。在低外输工况时,仅采用高压压缩方式处理BOG无法充分利用LNG冷能,且增压压缩机运行功率高、能耗较大。为此,利用ASPEN HYSYS软件,采用数值模拟与理论研究相结合的方法,对唐山LNG接收站BOG联合处理方案进行研究,制定并优化了再冷凝器与增压压缩机联合运行方案,以达到充分利用LNG冷能、降低增压压缩机运行功耗的目的。结果表明:BOG流量对下游LNG温度影响最大,调节再冷凝器下游LNG温度变化时应采用控制BOG流量为主、BOG温度与LNG总管流量为辅的调节手段;优化后的联合运行方案可降低增压压缩机功耗5%~20%,每年可节约用电约9.4×105kW·h,优化效果明显。研究成果可为LNG接收站BOG联合处理工艺计算及运行方案制定提供理论参考。(图7,表6,参26)

Two BOG treatment processes are adopted in the Tangshan LNG terminal of PetroChina,including the recondensation and highpressure compression based export processes.However,the LNG cold energy could not be fully used if only the high-pressure compression method is used for BOG treatment in the low export condition.The booster compressor has high operation power and large energy consumption.For this reason,the combined BOG treatment scheme of the Tangshan LNG terminal was studied through the combined numerical simulation and theoretical research with the ASPEN HYSYS software.Meanwhile,the combined operation scheme of the re-condenser and booster compressor was formulated to make full use of the LNG cold energy and reduce the operating power consumption of the booster compressor.The results show that the BOG flow has a great impact on the downstream LNG temperature.To control the downstream LNG temperature change of the re-condenser,the BOG flow should be controlled at first,with the auxiliary of BOG temperature and LNG header flow control.The combined operation scheme after optimization could reduce the power consumption of the compressor by 5%‒20%,so that about 9.4×105 kW·h power can be saved annually,with an obvious optimization effect.Generally,the research results could provide a theoretical reference for the calculation of the combined BOG treatment process in the LNG terminal and the formulation of the operation scheme.(7 Figures,6 Tables,26 References)