针对某厂对液氮洗工艺进行改造以尽可能达到回收甲烷、合成气中CO摩尔分数小于1×10^-6、LNG产品中的CH₄摩尔分数大于95%的工艺要求，采用Aspen Plus软件对工艺进行模拟优化，并提出了两段低压闪蒸连用的改造方案。模拟结果显示，合成气中CO摩尔分数符合要求，LNG产品中CH₄的摩尔分数为95.05%，除此之外氮气循环系统的氮气使用量减少了12.79%。

The liquid nitrogen washing process in a certain plant is renovated to meet the process requirements that methane is recovered as much as possible,the molar fraction of CO in ammonia synthesis gas shall be less than 1×10^-6,and the molar fraction of methane in liquefied natural gas (LNG) product shall be greater than 95%.Accordingly,the process is simulated and optimized by Aspen Plus software.Based on the simulation results,a coupled two-stage low-pressure flashing renovation scheme is supposed.The simulation results show that the molar fraction of CO in ammonia synthesis gas meets the requirement,the molar fraction of methane in the LNG product is 95.05%.Besides,the nitrogen consumption in the nitrogen circulation system drops by 12.79%.

肖铭(1992-),女,硕士生