Abstract: The present invention is a process for the liquefaction of high pressure natural gas. The natural gas is expanded through a turboexpander to reduce its pressure and thereby cool it. The natural gas is then passed through a demethanizer to remove the heavier components therefrom. The natural gas is then precooled, before substantial warming occurs, by heat exchange with a C.sub.2 hydrocarbon refrigerant, either ethane or ethylene, contained in a single refrigerant system. The precooled natural gas is liquefied by heat exchange with a mixed refrigerant contained in a mixed refrigerant system. The mixed refrigerant consists essentially of nitrogen, methane and a C.sub.2 hydrocarbon, either ethane or ethylene. The mixed refrigerant contained in the mixed refrigerant system is cooled by heat exchange with the C.sub.2 hydrocarbon refrigerant contained in the single refrigerant system.

Abstract: A process is disclosed for producing a purified liquefied natural gas (LNG) from a raw natural gas feed containing methane and hydrocarbon impurities of C.sub.2 and higher wherein the raw feed is cooled, distilled to remove impurities, and liquefied, such that the distillation reflux is supplied by a portion of a subcooled methane-rich liquid stream exiting the middle bundle of a three bundle main cryogenic heat exchanger having a mixed cryogenic refrigerant. The raw feed is cooled in the first bundle of said main exchanger.