LNG RV (LNG re-gasification vessel)
A new type of LNG tanker provided with re-gasification facilities. A tanker having loaded a LNG cargo in the conventional way regasifies the cargo on board and discharges the high-pressure gas at an offshore buoy or floating terminal. Gas is then fed directly into the consumer grid system through a dedicated mooring arrangement and sub-sea pipeline, thereby by-passing the need for a costly shore terminal which would normally carry out this process.
Discharge can be done either through deck manifolds or via a submerged turret mooring and offloading (STL) system, employing a turret installed at the bow. A buoy is moored to the seabed at the terminal and this is pulled into, and secured to, the turret mating cone in the ship bottom. A swivel in the turret allows the ship to weathervane without the aid of propulsion.
However, the vessel is free to roll and pitch and the cargo tanks and hull structure must withstand the sloshing loads which could be generated.
Delivered in 2005 by Daewoo Shipbuilding & Marine Engineering Co Ltd (DSME), the 138 000m3 EXCELSIOR is the first LNG vessel able to self discharge direct to a single buoy mooring (SBM) or into the local gas grid. The new vessel has been developed by DSME from its standard LNG tanker design, to which has been added re-gas plant and an internal turret for sub-sea pipe connection and weather-vane mooring. Cargo tanks and the supporting structures have been significantly reinforced because the LNG RV will be operating under partially filled tank conditions involving cargo sloshing. Additional equipment has been provided, with three 620m3/h feed pumps supplying a re-gas process. The re-gasification capacity is 500 million cubic feet per day, ensuring that a full cargo can be converted to high-pressure natural gas in five-to-six days. See also ENERGY BRIDGE concept.