BigPatents India

The present invention relates to a process for liquefying a pressurised feed gas which comprises: cooling the pressurised feed gas by indirect heat exchange in a first heat exchange zone with a first vaporising mixed refrigerant to yield a cooled feed gas and a first mixed refrigerant vapour; further cooling and condensing the cooled feed gas by indirect heat exchange in a second heat exchange zone with a second vaporising mixed refrigerant to yield a liquid product and a second mixed refrigerant vapour; compressing, cooling and condensing the first mixed refrigerant vapour; and flashing the resulting condensed first mixed refrigerant to provide the first vaporising mixed refrigerant; compressing the second mixed refrigerant vapour without preheating, cooling and condensing the compressed second mixed refrigerant and flashing the resulting compressed second mixed refrigerant to provide the second vaporising mixed refrigerant, wherein at least a portion of the refrigeration for the cooling and condensing of the second mixed refrigerant vapour is provided by indirect heat exchange in the first heat exchange zone with the first vaporising liquid mixed refrigerant; vaporizing the first mixed refrigerant in the first heat exchange zone at a first essentially constant pressure; vaporizing the second mixed refrigerant in the second heat exchange zone at a second essentially constant pressure; and compressing the first mixed refrigerant vapour in at least two stages of compression characterized in that the compression of the first mixed refrigerant Ivapor generates either: (a) at least one interstage two-phase refrigerant stream, which is separated into an interstage refrigerant vapour and an interstage refrigerant liquid; the interstage refrigerant vapour is compressed to yield a further compressed.