利用液化天然气冷能的朗肯循环与联合法发电系统流程的工艺模拟与对比分析

液化天然气(LNG)在再气化过程中具有巨大的冷能利用价值。目前回收LNG冷能的诸多方法中LNG冷能发电是最有可能大规模利用的方式,同时也是技术较为成熟的方法。在保证天然气入网压力及膨胀机最大承压的条件下,通过HYSYS流程模拟软件对以丙烷为工质的朗肯循环、天然气直接膨胀与朗肯循环相结合的联合循环进行流程模拟,并根据模拟得到的过程参数和输出功进行对比分析,总结了两种循环的特点和发电收益。如果以年蒸发量为150万吨、年工作小时为8000 h的LNG接收站作为分析的基础,并以工业用电价格0.55元·(kW·h)^-1计算,联合法的年发电收益将比朗肯循环法多487万元,以此可以作为两种循环流程经济性分析的基础,为流程全面的经济性分析提供可靠的依据。

Comparative analysis and simulation of power cycle to recovery cold energy of LNG

Cold energy utilization of liquefied natural gas(LNG)has tremendous values.Cold energy power generation is the most likely way to be large-scale used among the methods used to reclaim and utilize LNG cold energy.Based on pressure condition required of the natural gas network and the maximum pressure expander could endure,simulation studies of Rankine cycle with Propane as working fluid and combined method are carried out through HYSYS.The combined method is composed of two stage of natural gas direct expansion and the Rankine cycle with Propane as working fluid.The process parameters and the output electric powers are determined.If the annual evaporation is 1.5 million tons,the annual working hours of 8000 hours as a basis for analysis of LNG terminals,and industrial electricity price 0.55 CNY·(kW·h)^-1,the combined method of annual generation revenue will be 4.87 million more than Rankine cycle.The values can be used as the basis of economic analysis of two cycles,and also provide a reliable basis for a comprehensive economic analysis of the two processes.