Onboard Regasification of LNG Using Ambient Air

Abstract

Offshore regasification of liquid natural gas (LNG) is provided onboard an LNG carrier vessel for delivery onshore as a gas. The LNG is regasified to natural gas aboard the LNG carrier vessel using ambient air as the primary source of heat for regasification. Condensed water that accumulates from the ambient air during the regasification of LNG is collected, and the collected condensed water is used as ballast for the LNG carrier vessel.

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 side view of the RLNGC moored at a turret mooring buoy through which the natural gas is from the onboard regasification facility is transferred through a marine rise associated with a sub-sea pipeline to shore;

FIG. 2 is a flow chart illustrating one embodiment of the onboard regasification facility in which ambient air exchanges heat with an intermediate fluid and the intermediate fluid exchanges heat with the LNG to form natural gas; and,

FIG. 3 is a flow chart illustrating an alternative embodiment of the onboard regasification facility in which ambient air exchanges heat directly with LNG to form natural gas.

Claims

1. A method for offshore regasification of liquid natural gas (LNG) onboard an LNG carrier vessel for delivery onshore as a gas, the method comprising: a) regasifying LNG to natural gas aboard the LNG carrier vessel using ambient air as the primary source of-heat for regasification;b) collecting condensed water that accumulates from the ambient air during step a); and,c) using the collected condensed water from step b) as ballast for the LNG carrier vessel.

2. The method of offshore regasification of claim 1, wherein step a) comprises direct heat exchange between the ambient air and the LNG.

3. The method of offshore regasification of claim 1, wherein step a) comprises heat exchange between ambient air and an intermediate fluid to produce a heated intermediate fluid and the heated intermediate fluid exchanges heat with the LNG to regasify the LNG.

4. The method of offshore regasification of claim 1, wherein heat exchange between the ambient air and the regasification facility is encouraged through use of forced draft fans.

5. The method of offshore regasification of claim 1, further comprising the step of transferring the regasified natural gas to an onshore gas distribution facility for delivery to an end user.

6. The method of offshore regasification of claim 1, wherein the regasified natural gas is transferred to a subsea pipeline through a submersible, disconnectable mooring buoy locatable within a recess disposed within a portion of the hull of the LNG carrier vessel.

7. An LNG carrier vessel including a ballast tank to hold ballast water and a storage tank to hold LNG to be regasified, the LNG carrier vessel comprising: a regasification facility onboard the LNG carrier vessel using ambient air as the primary source of heat for vaporizing LNG to natural gas; and,a condensed water collection system to collect the condensed water from the regasification facility and to transfer the condensed water to the ballast tank of the LNG carrier vessel.

8. The LNG carrier vessel of claim 7, wherein the regasification facility includes a vaporizer to provide direct heating of the LNG using ambient air.

9. The LNG carrier vessel of claim 7, wherein the regasification facility includes a closed loop heat exchanger to heat an intermediate fluid using ambient air as the primary source of heat and a vaporizer to regasify LNG using the heated intermediate fluid.

10. The LNG carrier vessel of claim 7, further comprising forced draft fans to encourage heat exchange between ambient air and the regasification facility.

11. The LNG carrier vessel of claim 7, further comprising a recess disposed within the hull and toward the bow of the RLNGC to receive a submersible, disconnectable mooring buoy for mooring the RLNGC during regasification.