Patent ID: 8250883

Claim:
A system of producing Liquefied Natural Gas (LNG) comprising: (1) an offshore mobile structure, and (2) a natural gas liquefaction plant installed on the offshore mobile structure comprising a closed air refrigeration cycle comprising a point for periodically taking air from the environment in order to compensate for air loss in the refrigeration cycle, wherein the air is treated in order to eliminate water and carbon dioxide from the air prior to entry into at least one air compressor, at least one air compressor where the air from the environment is compressed to obtain compressed air, and wherein the air is re-circulated in the refrigeration cycle, at least one expander where the compressed air is expanded to obtain expanded air, at least one heat exchanger where natural gas is cooled with the expanded air and with an end-flash gas to obtain a cooled natural gas, an expansion device where the cooled natural gas is expanded to obtain an expanded cooled natural gas, an end-flash vessel where the expanded cooled natural gas is separated into liquefied natural gas (LNG) and the end-flash gas.