带膨胀机的煤层气液化流程计算及热力学分析

为了比较不同煤层气液化流程中的损失、能耗的差别,首先对制冷剂中甲烷（CH4）的摩尔分数对能耗的影响进行了优化计算,在此基础上应用流程优化软件和编程手段对2种典型的液化流程方案进行了理论计算,进而对其损失、能耗进行了比较和分析.结果表明：CH4摩尔分数为50%左右时耗功最小,有利于流程的优化;理论上＂丙烷预冷的N2-CH4单级膨胀液化循环＂的损失和能耗均小于＂N2-CH4串联双级膨胀液化循环＂.

Calculation and Thermodynamic Analysis on Liquefaction Processes of Natural Gas with Expanders

In order to compare the exergy loss and energy consumption of different liquefaction processes,the calculations of the energy consumption under different mol fractions of methane in refrigerants were performed.The result shows that the energy consumption is smallest and the liquefied process can be optimized when the mol fraction of methane is 50%.Then two processes for liquefied natural gas production were evaluated,including a single-stage expander nitrogen-methane refrigerant with another propane refrigeration cycle(1st project) and a two-stage expander nitrogen-methane refrigerant(2nd project).Steady-state simulations and calculations were conducted to ensure that each process was compared on an identical basis.The full energy and exergy analysis including feed-in gas and refrigerant stream shows that the 1st project has lower exergy loss and less energy consumption.