Onboard Regasification of LNG

Abstract

A method is provided for offshore regasification of liquid natural gas (LNG) for delivery onshore as a gas. The method includes offloading LNG from a first LNG Carrier to a second LNG Carrier at an offloading location, the second LNG Carrier including an onboard regasification facility, transferring the second LNG Carrier from the offloading location to a mooring location closer to shore, regasifying the LNG onboard the second LNG Carrier to form natural gas, and transferring the regasified natural gas to an onshore gas distribution facility for delivery to an end user.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a more detailed understanding of the nature of the invention several embodiments of the present invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic plan view of a first embodiment of the method of onboard regasification of the present invention illustrating the first and second LNG Carrier positioned at an offloading location during offloading of the LNG from the first LNG Carrier to the second LNG Carrier fitted with an onboard regasification facility;

FIG. 2 is a schematic side view of the embodiment of FIG. 1 illustrating the second LNG Carrier moored at a turret mooring buoy as the LNG is regasified onboard the second LNG Carrier and transferred through a marine riser and associated sub-sea pipeline to shore; and,

FIG. 3 illustrates one possible flow diagram for the regasification facility onboard the second LNG Carrier.

Claims

1. A method for offshore regasification of liquid natural gas (LNG) for delivery onshore as a gas, the method comprising: offloading LNG from a first LNG Carrier to a second LNG Carrier at an offloading location, the second LNG Carrier including an onboard regasification facility;transferring the second LNG Carrier from the offloading location to a mooring location closer to shore;regasifying the LNG onboard the second LNG Carrier to form natural gas; and,transferring the regasified natural gas to an onshore gas distribution facility for delivery to an end user.

2. The method of claim 1, wherein the LNG is offloaded from the first LNG Carrier to the second LNG Carrier using side-by-side loading on one side of the second LNG Carrier.

3. The method of claim 2, wherein the first and second LNG Carriers are underway and traveling side-by-side when LNG is offloaded from the first LNG Carrier to the second LNG Carrier.

4. The method of claim 2, wherein the first and second LNG Carriers are drifting side-by-side when LNG is offloaded from the first LNG Carrier to the second LNG Carrier.

5. The method of claim 2, wherein the second LNG Carrier is provided with fendering equipment and mooring facilities to allow side-to-side offloading with the first LNG Carrier.

6. The method of claim 2, wherein the first and second LNG Carriers are traveling in tandem when LNG is offloaded from the first LNG Carrier to the second LNG Carrier by tandem offloading.

7. The method of claim 1, wherein the second LNG Carrier is provided with one or more storage tanks and the storage tanks are hydrostatically stable when partially filled with LNG.

8. The method of claim 1, wherein the LNG is stored in the hull of the second LNG Carrier in slosh tolerant tanks and the second LNG Carrier has an associated supporting hull structure.

9. The method of claim 1, wherein the second LNG Carrier has reduced engine capacity compared with the engine capacity of the first LNG Carrier.

10. The method of claim 1, wherein the second LNG Carrier has a propulsion system and the propulsion system comprises dual fuel gas turbines, dual fuel diesel, or duel fuel diesel-electric systems.

11. The method of claim 1, wherein the power requirement for the propulsion system of the second LNG Carrier is shared with the power requirement for regasification onboard the second LNG Carrier.

12. The method of claim 1, wherein the propulsion system comprises twin screw, fixed pitch propellers with transverse thrusters located both forward and aft that provide the second LNG Carrier with mooring and position capability.

13. The method of claim 1, wherein the mooring location includes a mooring buoy removably disconnectable to the second LNG Carrier for mooring the second LNG Carrier at the mooring location, the mooring buoy being locatable within a recess disposed within the hull and towards the bow of the second LNG Carrier.

14. The method of claim 13, wherein the mooring buoy is a submersible turret mooring buoy.

15. The method of claim 13, wherein the natural gas is transferred to shore through the mooring buoy.

16. The method of claim 1, wherein the natural gas is transferred from the second LNG Carrier through a subsea pipeline to an on-shore tie-in point via a beach crossing.

17. The method of claim 1, wherein the LNG is regasified using ambient air as a source of heat.

18. The method of claim 1, wherein the LNG is regasified through heat exchange with an intermediate fluid and the intermediate fluid is heated using ambient air as a source of heat.

19. The method of claim 18, wherein heat exchange between the ambient air and the LNG or intermediate fluid is encouraged through use of forced draft fans

20. The method of claim 1, further comprising flowing regasified natural gas into a second heat exchanger in which the regasified natural gas is heated and is transferred to shore as superheated vapor.

21. The method of claim 20, wherein the regasified natural gas is heated in the second heat exchanger using waste heat recovery from the second LNG Carrier.

22. The method of claim 1, wherein the LNG is regasified in a closed loop heat exchanger.

23. The method of claim 1, wherein the LNG is regasified in a finned tube heat exchanger.