FIELD: gas industry.
SUBSTANCE: invention relates to liquefaction of natural gas. Method of liquefying a gas involves feeding a completely condensed first mixed refrigerant, a compressed second mixed refrigerant and a feed stream into a first cooling system. Further, the first mixed refrigerant is expanded to cool the supplied flow and the compressed second mixed refrigerant in the first cooling system by means of heat exchange with the expanded first mixed refrigerant to form the first cooled flow and the completely condensed second mixed refrigerant. Second mixed refrigerant is expanded. First cooled flow is cooled in the second cooling system by means of heat exchange with the expanded second mixed coolant with formation of the second cooled flow. First or the second cooled flow is expanded in the turbine expander. Expanded flow is separated in separator. Vapour head fraction is compressed in compressor driven by turboexpander. If the first cooled flow is expanded, the compressed vapour fraction is cooled in the first cooling system. If the second cooled flow is expanded, the compressed vapour fraction is cooled in the second cooling system.
EFFECT: technical result is reduction of energy consumption.
19 cl, 7 dwg
