US 11,885,561 B2
Low global-warming refrigerants in LNG processing
Paul Davies, Richmond, TX (US); James Lee Harris, Jr., Katy, TX (US); Emery Jay Thomas, Sugar Land, TX (US); and Gregg Sapp, Houston, TX (US)
Assigned to CONOCOPHILLIPS COMPANY, Houston, TX (US)
Filed by Paul Davies, Richmond, TX (US); James Lee Harris, Jr., Katy, TX (US); Emery Jay Thomas, Sugar Land, TX (US); and Gregg Sapp, Houston, TX (US)
Filed on Nov. 20, 2013, as Appl. No. 14/085,372.
Claims priority of provisional application 61/733,293, filed on Dec. 4, 2012.
Prior Publication US 2014/0150491 A1, Jun. 5, 2014
Int. Cl. F25J 1/00 (2006.01); F25J 1/02 (2006.01); C09K 5/04 (2006.01)
CPC F25J 1/0022 (2013.01) [C09K 5/042 (2013.01); C09K 5/045 (2013.01); F25J 1/0062 (2013.01); F25J 1/0097 (2013.01); F25J 1/0256 (2013.01); F25J 1/0278 (2013.01); C09K 2205/126 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for liquefying natural gas offshore to produce liquified natural gas (LNG), said method 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 mole percent propane and an environmentally-friendly low combustibility refrigerant comprising 10-25 mole percent fluorinated olefin, wherein the laminar burning velocity (LBV) of said first mixture is about 40 cm/s and decreases the risk of vapor cloud explosion as compared to mixtures having LBV>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 in an open refrigeration cycle with 75-100 mole percent methane; and
d) producing LNG.