天然气液化系统露点的定量分析

Quantitative analysis of dew point of natural gas liquefaction system

在天然气液化系统中,水露点凝结而成的液滴会造成相关设备发生露点腐蚀,而烃露点凝结而成的液滴不会导致设备发生露点腐蚀,反而可以抑制露点腐蚀的发生。为找到天然气水露点和烃露点的临界点,采用Aspen Plus软件建立了天然气露点定量分析模型,对天然气液化系统中的轻组分天然气和含有微量重组分天然气的露点进行了定量分析,同时分析了天然气压力以及天然气中CO_(2)物质的量分数对露点的影响。结果表明,轻组分天然气的露点类型为水露点,会对天然气液化系统相关设备造成露点腐蚀;天然气中微量的C6重组分不会对露点温度及露点溶液组成造成影响,而微量的C7、C8和C9重组分则会改变露点温度及露点溶液组成。可通过向天然气中增添微量C_(9)及C_(10+)重组分来预防天然气液化系统相关设备发生露点腐蚀。

In the natural gas liquefaction system,droplets formed by condensation of water dew point will cause dew point corrosion of relevant equipment,while the droplets formed by condensation of hydrocarbon dew point will not cause dew point corrosion of equipment,but can inhibit the occurrence of dew point corrosion.In order to find the critical point of water dew point and hydrocarbon dew point of natural gas,a quantitative analysis model of natural gas dew point was established by Aspen Plus software.The dew point of light component natural gas and natural gas containing trace heavy component in natural gas liquefaction system was quantitatively analyzed.The influence of natural gas pressure and mole fraction of CO2 in natural gas on dew point was analyzed.The results show that the dew point type of light component natural gas is water dew point,which will cause dew point corrosion to the related equipment of natural gas liquefaction system.Trace C6 heavy components in natural gas will not affect the dew point temperature and dew point solution composition,while trace C7,C8 and C9 heavy components will change the dew point temperature and dew point solution composition.Dew point corrosion of related equipment in natural gas liquefaction system can be prevented by adding trace C9 and C10+heavy components in natural gas.