Low global-warming refrigerants in LNG processing
AssigneeConocoPhillips Company
InventorsPaul Davies, James Lee Harris, Jr., Emery Jay Thomas, Gregg Sapp
Life of this patent
Estimating the term…
Abstract
Methods and systems for liquefying natural gas using environmentally-friendly low combustibility refrigerants are provided. Methods of liquefaction include cooling a fluid in an LNG facility via indirect heat exchange with an environmentally-friendly low combustibility refrigerant selected from the group consisting of: a fluorinated olefin, xenon, any derivative thereof, and any combination thereof.
Claims9
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.
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.
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.
A method for liquefying natural gas in an offshore facility 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 85 mole percent propane and an 15 mole percent 1234yf, wherein the laminar burning velocity (LBV) of said first azeotropic mixture is about 40 cm/s and decreases the risk of vapor cloud explosion as compared to mixtures of 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 1234yf and ethylene;
- and then
- c) further cooling the natural gas stream in an open refrigeration cycle with 75-100 mole percent methane, wherein about 50 mole percent of said methane originates from LNG produced in step d in said method;
- and
- d) producing LNG.
Dependencies are inferred from the claim text.