液化天然气工厂低品位氦资源提取工艺研究

Study on Extraction Process of Helium Resources from Low-grade Helium in Liquefied Natural Gas Plants

氦资源是战略资源,而我国是贫氦国家,氦资源对外依存度90%以上,如何利用液化天然气工厂低品位氦资源,减少对进口氦资源的依赖,是关乎我国氦资源供应安全的重大课题。为此结合LNG工厂工艺特点及粗氦提取工艺特点,提出了三种提取粗氦工艺,并进行了详细的工艺描述、工艺方案对比、工艺适用性确定。从而得出结论:利用对LNG工厂工艺的适当延伸回收氦资源既有技术可行性又有较好的经济性,从而避免氦资源的浪费;对有BOG再液化流程的LNG工厂,采取BOG闪蒸提粗氦工艺为最佳工艺选择;对无BOG再液化流程的LNG工厂,推荐采用LNG闪蒸提粗氦工艺;BOG闪蒸及LNG闪蒸提粗氦工艺粗氦浓度受原料气组分、闪蒸温度及闪蒸压力的影响,但控制粗氦浓度最有效的手段为调节闪蒸压力。

Helium is a national strategic resource,and China is a helium poor country with over 90%external dependence on helium resources.The utilization of low-grade helium in liquefied natural gas plants to reduce dependence on imported helium is a major issue related to the security of helium resource supply in China.Therefore,three process flows for extracting crude helium were proposed based on the characteristics of LNG plant processes and characteristic of Crude helium extraction processes,detailed process descriptions,process scheme comparisons,and determination of process applicability were carried out for them.After research,it was concluded that:it was technically feasible and economically feasible to appropriately modify the process flow of LNG plants to recover helium resources,avoiding the waste of helium resources.For LNG plants with BOG re-liquefaction process,using BOG flash process to extract crude helium was the best process choice,for LNG plants without BOG re-liquefaction process,it was recommended to use LNG flash to extract crude helium.The concentration of crude helium in BOG flash and LNG flash processes was affected by the composition of the feed gas,flash temperature and flash pressure.However,the most effective way to control the concentration of crude helium was to adjust the flash pressure.