Patent ID: 11885561
Assignee: CONOCOPHILLIPS COMPANY
Field: Chemical engineering (Chemistry)
Classification: CPC F  C | IPC C  F

Claim 6:
7. A method for liquefying natural gas to produce LNG, comprising:
a) cooling a natural gas stream in an offshore LNG facility via indirect heat exchange in a first refrigeration cycle with a first azeotropic mixture of 75-90% of propane by volume and an environmentally-friendly low combustibility refrigerant comprising 10-25% fluorinated olefin by volume, wherein the laminar burning velocity of said first mixture is less than 40 cm/s and decreases the risk of vapor cloud explosion as compared to mixtures having LBV greater than 40 cm/s; and then
b) further cooling the natural gas stream via indirect heat exchange in a second refrigeration cycle with a second azeotropic mixture of the fluorinated olefin and ethylene; and then
c) further cooling the natural gas stream via a third open refrigeration cycle with 75-100 mole percent methane, wherein 50 mole percent of said methane originates from processed natural gas produced in said method; and
d) producing LNG.