Process and apparatus for the liquefaction of natural gas

摘要

A process for liquefaction of natural gas comprising the steps of: compressing a fluid refrigerant 550; cooling the compressed refrigerant 500 in heat exchange with a cooling fluid to provide a cooled compressed refrigerant 525; work-expanding at least a first portion of the cooled compressed refrigerant 525 in a first turbo-expander 530 to provide an expanded cooled refrigerant 535; reheating the expanded cooled refrigerant 535 in a liquefaction heat exchange system 505 to provide a reheated refrigerant 550; returning the reheated refrigerant 550 to be recompressed; providing a natural gas feed stream 400; compressing the natural gas feed stream 400; passing the compressed natural gas feed stream 410 directly or indirectly to heat exchange with the expanded cooled refrigerant 535 in the liquefaction heat exchange system 505; and withdrawing a cooled and at least partly condensed natural gas product 450 from the liquefaction heat exchange system 440; wherein the first turbo-expander 530 is used to drive a compressor 405 to compress the natural gas feed stream 400. There may be a second turbo-expander to drive the refrigerant compressor, and the refrigerant may be nitrogen. An apparatus for performing the method is also disclosed.