PROCESS AND APPARATUS FOR THE LIQUEFACTION OF NATURAL GAS

摘要

This invention relates to processes and apparatus for the liquefaction of natural gas. In particular, the invention relates to processes and apparatus in which expansion of a refrigerant through a turbo-expander as part of a refrigeration cycle is used to drive a compressor which increases the pressure of the natural gas feed to the liquefaction process. More specifically, the invention relates to a process for liquefaction of natural gas comprising the steps of: (a) providing a refrigeration cycle comprising the steps of: (i) compressing a fluid refrigerant; (ii) cooling the compressed refrigerant from step (i) in heat exchange with a cooling fluid to provide a cooled compressed refrigerant; (iii) work-expanding at least a first portion of the cooled compressed refrigerant from step (ii) in a first turbo-expander to provide an expanded cooled refrigerant; (iv) reheating the expanded cooled refrigerant from step (iii) in a liquefaction heat exchange system to provide a reheated refrigerant; and (v) returning the reheated refrigerant from step (iv) to step (i); (b) providing a natural gas feed stream; (c) compressing the natural gas feed stream; (d) passing the compressed natural gas feed stream directly or indirectly to heat exchange with the expanded cooled refrigerant from step (iii) in the liquefaction heat exchange system; and (e) withdrawing a cooled and at least partly condensed natural gas product from the liquefaction heat exchange system; wherein the first turbo-expander is used to drive a compressor to compress the natural gas feed stream in step (c).