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.