Gas liquefaction by a fractionally condensed refrigerant

Claim 1

A process for the liquefaction of natural gas by indirect heat exchange with a compressed multi-component refrigerant circulated in a closed cooling cycle comprising the following steps: a. cooling, fractionally condensing and separating said compressed multi-component refrigerant into only a single higher boiling liquid and a single lower boiling gaseous fraction, b. subcooling all of said higher boiling liquid fraction and further cooling, liquefying and subcooling said lower boiling gaseous fraction, c. expanding all of said subcooled higher boiling and lower boiling liquid fractions to different pressures, said subcooled higher boiling liquid fraction being expanded to a higher pressure, and said subcooled lower boiling liquid fraction being expanded to a lower pressure, d. separately evaporating and heating to ambient temperature said subcooled liquid fractions expanded to different pressures by indirect heat exchange with said higher boiling and lower boiling fractions of said multi-component refrigerant and with said natural gas to be liquefied, without mixing said higher boiling and lower boiling fractions during evaporation and heating to ambient temperature, e. separately recycling said two evaporated fractions previously expanded to different pressures to a multi-stage compressor and mixing said two evaporated fractions only during the compression.