LNG物理及其回收利用

Analysis and recycle of LNG physical exergy

液化天然气储存在-160℃左右的低温下,这种与环境状态的巨大差别,使得LNG在蒸发时可释放大量的冷能。为了回收利用LNG所具有的冷能,采用Peng-Robinson气液平衡状态方程,使用HYSYS软件对LNG的蒸发过程进行了模拟计算。研究了LNG冷能和物理在不同蒸发压力下的释放情况,并考虑了甲烷的摩尔分数对此的影响,结果表明蒸发压力对LNG冷能的回收利用方式有决定性影响。依据研究结果,提出了采用Rankine循环和Brayton循环的方法来实现LNG物理回收利用。

LNG is stored at about - 160 ℃ , which is much different from the atmosphere temperature. The difference makes LNG contain a large amount of physical exergy. To recycle LNG cold energy, the Peng-Robinson state equation and HYSYS were adopted to simulate the evaporation of LNG. The amount of LNG cold energy and physical exergy when vaporizing in different pressure was studied,and the influence of methane mole fraction on the LNG cold energy and physical exergy was also analyzed. The resuhs show that the evaporation pressure is the key parameter of the recycle style of LNG cold energy and physical exergy. According to the resuhs,Rankine cycle and Brayton cycle are advised to recycle LNG physical exergy.