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US 6,658,890 B1Granted
Enhanced methane flash system for natural gas liquefaction
AssigneeConocoPhillips Company
InventorsPaul R. Hahn, Jame Yao, Rong-Jwyn Lee, Ned P. Baudat
Life of this patent
Estimating the term…
Abstract
Natural gas liquefaction system employing an open methane cycle wherein the liquefied natural gas is flashed immediately upstream of the liquefied natural gas storage tank and boil off vapors from the tank are returned to the open methane cycle.
Claims39
A process for liquefying natural gas, said process comprising the steps of:
- (a) flashing a pressurized liquefied natural gas stream in a first expander to provide a first flash gas and a first liquid stream;
- (b) flashing at least a portion of the first liquefied stream in a second expander to provide a second flash gas and a second liquid stream;
- (c) flashing at least a portion of the second liquid stream at or immediately upstream of a liquefied natural gas storage tank, thereby providing a third flash gas and a final liquefied natural gas product;
- and
- (d) conducting the third flash gas and the final liquefied natural gas product to the liquefied natural gas storage tank.
2 more elements
A process for liquefying natural gas, said process comprising the steps of:
- (a) flashing a pressurized liquefied natural gas stream in a first expander to provide a first flash gas and a first liquid stream;
- (b) flashing at least a portion of the first liquefied stream in a second expander to provide a second flash gas and a second liquid stream;
- (c) flashing at least a portion of the second liquid stream at or immediately upstream of a liquefied natural gas storage tank, thereby providing a third flash gas and a final liquefied natural gas product;
- (d) upstream of the liquefied natural gas storage tank, splitting at least a portion of the second liquid stream into a refrigerant portion and a product portion;
- (e) conducting the refrigerant portion and at least a portion of the third flash gas to a common conduit;
- (f) combining the refrigerant portion and at least a portion of the third flash gas in the common conduit, said common conduit being a cold side of an indirect heat exchanger;
- and
- (g) upstream of the liquefied natural gas storage tank, subcooling the second flash gas stream by indirect heat exchange in the heat exchanger.
5 more elements
A process for liquefying natural gas, said process comprising the steps of:
- (a) flashing a pressurized liquefied natural gas stream in a first expander to provide a first flash gas and a first liquid stream;
- (b) flashing at least a portion of the first liquid stream in a second expander to provide a second flash gas and a second liquid stream;
- (c) subcooling at least a portion of the second liquid stream in a heat exchanger, thereby providing a subcooled liquefied natural gas stream;
- and
- (d) conducting at least a portion of the subcooled liquefied natural gas stream to a liquefied natural gas storage tank.
2 more elements
A process for liquefying natural gas, said process comprising the steps of:
- (a) flashing a first liquefied natural gas stream in a first expander to provide a first flash gas and a first liquid stream;
- (b) conducting a product portion of the first liquid stream to a liquefied natural gas storage tank, said product portion comprising both liquid and vapor;
- (c) conducting a refrigerant portion of the first liquid stream to a heat exchanger;
- (d) conducting natural gas vapors from the liquefied natural gas storage tank to the heat exchanger;
- and
- (e) combining the natural gas vapors and the refrigerant portion in the heat exchanger.
3 more elements
An apparatus for liquefying natural gas, said apparatus comprising:
- a first liquid expander having a first expander outlet;
- a first gas-liquid separator fluidly coupled to the first expander outlet and having a first gas outlet and a first liquid outlet;
- a second liquid expander fluidly coupled to the first liquid outlet and having a second expander outlet;
- a second gas-liquid separator fluidly coupled to the second expander outlet and having a second gas outlet and a second liquid outlet;
- an indirect heat exchanger defining a first fluid flow path and a second fluid flow path, said first and second fluid flow paths being fluidly isolated from one another, said heat exchanger defining first and second flow path inlets and outlets for the first and second fluid flow paths respectively, said first flow path inlet being fluidly coupled to the second liquid outlet;
- a splitter fluidly coupled to the first flow path outlet and having a product outlet and a refrigerant outlet;
- and
- a liquefied natural gas storage tank having a tank inlet fluidly coupled to the product outlet.
5 more elements
Dependencies are inferred from the claim text.