LNG Vapor Handling Configurations And Methods

• US 20090217676A1
• Filed: 04/13/2007
• Published: 09/03/2009
• Est. Priority Date: 04/13/2006
• Status: Active Grant

• Current Assignee: Fluor Technologies Corporation (Fluor Corporation)
• Original Assignee: Fluor Technologies Corporation (Fluor Corporation)
• Inventors: Mak, John
• Granted Patent: US 8,117,852 B2
• Time in Patent Office: Days
• US Class Current: 62/50.100
• CPC Class Codes: F17C 2205/0364 flexible or articulated, e.g. a hose
• CPC Class Codes: F17C 2205/0367 Arrangements in parallel
• CPC Class Codes: F17C 2221/033 Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
• CPC Class Codes: F17C 2223/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2223/0169 subcooled
• CPC Class Codes: F17C 2223/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2223/035 High pressure (>10 bar)
• CPC Class Codes: F17C 2223/046 in the liquid
• CPC Class Codes: F17C 2225/0123 gaseous, e.g. CNG, GNC
• CPC Class Codes: F17C 2225/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2225/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2227/0135 Pumps
• CPC Class Codes: F17C 2227/0178 in the vessel
• CPC Class Codes: F17C 2227/0302 by heating
• CPC Class Codes: F17C 2227/0339 using the same fluid
• CPC Class Codes: F17C 2227/0388 separate
• CPC Class Codes: F17C 2227/0393 using a vaporiser
• CPC Class Codes: F17C 2260/023 Avoiding overheating
• CPC Class Codes: F17C 2265/017 different phases of a same fluid
• CPC Class Codes: F17C 2265/032 by recovery
• CPC Class Codes: F17C 2265/034 : with condensing the gas phase
• CPC Class Codes: F17C 2265/037 : with pressurising
• CPC Class Codes: F17C 2265/05 : Regasification
• CPC Class Codes: F17C 2270/0105 : Ships
• CPC Class Codes: F17C 2270/0136 : Terminals
• CPC Class Codes: F17C 6/00 : Methods and apparatus for filling vessels not under pressure with liquefied or solidified gases
• CPC Class Codes: F17C 9/00 : Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure

Abstract

LNG from a carrier is unloaded to an LNG storage tank in configurations and methods in which expansion of compressed and condensed boil-off vapors from the LNG storage tank provide refrigeration to subcool the LNG that is being unloaded. Most advantageously, such configuration and methods reduce the amount of boil-off vapors and eliminate the need for a vapor return line and associated compressor.

Claims

1. A system for transfer of LNG from an LNG carrier to an LNG storage tank comprising an exchanger that is configured to subcool the LNG coming from the carrier using refrigeration content of sendout LNG and the condensed and expanded boil-off from the LNG storage tank.

2. The system of claim 1 further comprising a separator fluidly coupled and downstream of the exchanger and configured to separate the sendout LNG and the condensed and expanded boil-off from the LNG storage tank into a vapor phase and a liquid phase.

3. The system of claim 2 further comprising a return line that is configured to feed the vapor phase to the LNG carrier.

4. The system of claim 2 further comprising a pump that is configured to pump the liquid phase to the LNG storage tank.

5. The system of claim 1 further comprising a compressor that is configured to receive boil-off from the LNG storage tank.

6. The system of claim 5 further comprising a bypass that is configured to provide LNG liquid to the compressed boil-off from the LNG storage tank.

7. The system of claim 1 further comprising a condenser or absorber that is configured to receive compressed boil-off from the LNG storage tank and that is further configured to receive sendout liquid from the LNG storage tank to thereby form condensed boil-off from the LNG storage tank.

8. A plant comprising:

an LNG source that is configured to provide an LNG stream and that is fluidly coupled to an LNG storage tank that is configured to provide a sendout LNG and an LNG vapor;

a compressor, and a condenser or absorber fluidly coupled to the LNG storage tank and configured to receive the LNG vapor and to provide a pressurized sendout LNG liquid;

a pressure reduction device configured to reduce pressure of the pressurized sendout LNG liquid; and

a heat exchanger that is configured to subcool the unloaded LNG stream using the depressurized sendout LNG liquid from the pressure reduction device.

9. The plant of claim 8 wherein the pressure reduction device is configured to cool by reduction of pressure the sendout LNG liquid to a temperature that is lower than the temperature of the unloaded LNG source.

10. The plant of claim 8 further comprising a separator that is located downstream of the heat exchanger and that is configured to receive depressurized heated saturated LNG liquid and to provide a vapor and a liquid.

11. The plant of claim 10 further comprising a return arm that is configured to deliver the vapor from the separator to the LNG source, and further comprising a pump that is configured to pump the depressurized liquid to the LNG storage tank.

12. A method of transferring an LNG stream from an LNG source comprising:

forming a pressurized sendout LNG liquid from a vapor of an LNG storage tank, and depressurizing the pressurized sendout LNG liquid; and

cooling the LNG stream using a heat exchanger that receives refrigeration content from the depressurized sendout LNG liquid.

13. The method of claim 12 wherein the depressurized LNG liquid is heated in the heat exchanger and separated into a vapor portion and a liquid portion.

14. The method of claim 13 wherein the liquid portion is fed to the LNG storage tank.

15. The method of claim 13 wherein the vapor portion is fed to the LNG source.

16. The method of claim 12 wherein the LNG stream is subcooled at least 1°

F.

17. The method of claim 12 wherein the vapor of the LNG storage tank is a boil-off vapor.

18. The method of claim 17 wherein the vapor is compressed and mixed with sendout LNG, and wherein the mixture is condensed in a condenser or absorber to thereby form the pressurized sendout LNG liquid.

19. The method of claim 18 wherein a portion of the pressurized sendout LNG liquid is combined with sendout LNG upstream of a vaporizer.

20. The method of claim 12 wherein the LNG source is an LNG carrier.