Patent ID: 8899074

Claim:
A method of natural gas liquefaction, comprising: directing a gaseous natural gas process stream comprising carbon dioxide and a cooling stream into a plant; cooling the gaseous natural gas process stream by transferring heat from the gaseous natural gas process stream to the cooling stream; expanding the cooled gaseous natural gas process stream to form a liquid natural gas process stream, a solid carbon dioxide portion suspended in the liquid natural gas stream, and a first tail gas stream comprising a gaseous natural gas; separating the solid carbon dioxide portion from at least a portion of the liquid natural gas process stream to provide a substantially pure liquid natural gas; sublimating the solid carbon dioxide; directing the first tail gas stream out of the plant at a first pressure; directing the sublimated carbon dioxide out of the plant in the first tail gas stream; separating a secondary liquid natural gas stream from the liquid natural gas process stream and vaporizing the secondary liquid natural gas stream with a heat exchanger to form a second tail gas stream comprising gaseous natural gas; and directing the second tail gas stream out of the plant at a second pressure, the second pressure different than the first pressure of the first tail gas stream.