混合工质循环与氮膨胀循环的经济性分析

近几年国内天然气液化技术主要采用混合工质液化循环和氮膨胀液化循环。为探讨两种流程的经济性，设计了混合工质液化循环和双级氮膨胀液化循环两种流程，分别对这两种流程进行了模拟，优化了流程的参数，并对它们的投资和运行费用等进行了分析。混合工质液化循环比氮膨胀液化循环复杂，设计计算困难，但其运行费用仅为氮膨胀液化循环的三分之二，而初期投资也比双级氮膨胀循环要低。混合工质循环投资少、功耗低、经济性好，应是国内发展小型天然气液化装置的首选流程。

ECONOMIC ANALYSIS COMPARED BETWEEN MIXED REFRIGERANT CYCLE AND NITROGEN EXPANDER CYCLE

Natural gas liquification involves both mixed refrigerant cycle and nitrogen expander cycle. In order to discuss on the cost effectiveness of these two cycles, this study set up two models on which their flow process could be simulated. Through simulation, this study applied the optimized parameters to calculate their investment costs and operation costs respectively. The result showed that although being complex in flow process and more difficult to calculate in its design the mixed refrigerant cycle should be the first choice for small scale natural gas liquification plants because of its low cost either in the former investment or in its latter operation, only two thirds of that in nitrogen expander cycle.