高含乙烷天然气氮膨胀液化分离流程

在液化页岩气的同时分离制取液化乙烷是一种经济合理的选择。采用HYSYS软件进行流程模拟研究，在传统氮膨胀液化流程的基础上设计了一种高含乙烷天然气的液化分离流程，并根据天然气中的乙烷含量，取10%、20%、30%、40%共4种含量，分析比较了不同液化压力下流程的比功耗。为降低流程的能耗，在满足LNG产品中C₂H₆含量小于1%、液化乙烷纯度达到99.5%的情况下进一步研究了制冷剂流量、氮气膨胀机出口压力、节流温度的影响，在此基础上结合HYSYS软件中的优化器进一步对流程进行了优化。结果表明，对应10%、20%、30%、40%的乙烷含量，比功耗分别降低7.24%、6.13%、5.8%、7.07%。

Nitrogen expansion liquefaction and separation process for natural gas with high ethane content

It is an economical and reasonable choice to separate ethane at the same time of natural gas liquefaction. On the basis of the conventional nitrogen expansion cycle, a nitrogen expansion liquefaction and separation process for natural gas with high ethane content is proposed. Four different kinds of natural gas, with ethane contents of 10%, 20%, 30% and 40%, are investigated with the proposed process by using the process simulation software HYSYS to analyze and compare the specific power consumption of the liquefaction process under different liquefaction pressure. In order to reduce the energy consumption of the process, the influence of the refrigerant flow rate, the outlet pressure of the nitrogen expander and the throttle temperature are further studied under the condition that the C₂H₆ content of the LNG product is less than 1% and the purity of the liquefied ethane is up to 99.5%. On this basis, the process is optimized in combination with the optimizer in the HYSYS software. The results show that, when the ethane contents are 10%, 20%, 30%, 40%, the specific power consumption decreases by 7.24%, 6.13%, 5.8%, and 7.07%, respectively.