Patent ID: 6367286
Filing Date: 2002-04-09
Classification: F25J

Abstract:
A process for liquefying a natural gas stream having a pressure greater than about 500 psig in a mixed refrigerant process to produce a liquefied natural gas product, the method comprising:a) cooling the natural gas stream in a heat exchanger in the mixed refrigerant process to a first temperature less than about âˆ’40_F. to produce a cooled natural gas stream; b) passing the cooled natural gas stream to a liquids separation zone to produce a first gas stream and a first liquids stream; c) passing the first liquids stream to a methane separation tower at a temperature less than about âˆ’40Â° F. and at a pressure less than about 650 psig to produce a second gas stream comprising methane and a second liquids stream containing natural gas liquids; d) passing the first gas stream to a turbo expander to reduce the pressure of the first gas stream to a pressure less than about 650 psig to produce a reduced pressure gas stream and passing the reduced pressure gas stream to the methane separation vessel; e) driving a compressor with the turbo expander; f) passing the second gas stream to the compressor and compressing the second gas stream to a pressure of at least about 500 psig to produce a compressed gas stream; and, g) passing the compressed gas stream to the heat exchanger for liquefaction at a pressure of at least about 500 psig to produce the liquefied natural gas.