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

Claim 5:
6. A method for liquefying natural gas offshore to produce liquified natural gas (LNG), said method comprising:
a) cooling a natural gas stream via indirect heat exchange in a first refrigeration cycle with a first azeotropic mixture of 75-90 mole percent propane and 10-25 mole percent of a fluorinated olefin, wherein the laminar burning velocity of said first mixture is 40 cm/s and decreases the risk of vapor cloud explosion as compared to mixtures having LBV>40 cm/s;
b) further cooling the natural gas stream via indirect heat exchange in a second refrigeration cycle with a second azeotropic mixture of ethylene and said fluorinated olefin,
c) further cooling the natural gas stream via a third open refrigeration cycle with 75-100 mole percent methane; and
d) producing LNG.