Mitsubishi Heavy Industries, Ltd. (MHI) has completed the development of a new-generation liquefied natural gas (LNG) carrier which, it claims, marks an 'evolutionary advance' for Moss-type LNG carriers.
The new vessel-type, dubbed "
EXTREM", is a newly-developed "Sayaendo" Series featuring a peapod-shaped continuous cover for the moss spherical tanks, which is integrated with the ship's hull in lieu of a conventional hemispherical cover.
According to MHI, the new configuration enables greater structural efficiency and size and weight reductions, resulting not only in improvements in
fuel consumption and operating economy but also in enhancements in terms of compatibility with LNG terminals and maintainability.
"MHI looks for the EXTREM to become a strategic product that will lead the LNG carrier market. The company is now targeting early order receipts," MHI said in a statement.
In conventional Moss-type LNG carriers, the upper half of the spherical storage tanks above the ship's deck is covered by a semispherical dome and the lower half under the deck is supported by a cylindrical skirt structure. In contrast, the EXTREM employs a continuous cover integrated with the ship's hull to house all storage tanks entirely, enabling the cover to be used as hull reinforced material for overall strength.
In the conventional method, pipes, wires and catwalks atop the tanks were supported by complex structures. By covering the tanks with the integrated cover and making those supporting structures unnecessary, the new design is said to improve maintainability.
According to MHI, the continuous cover over the tanks improves aerodynamics by substantially reducing wind pressure which serves as a drag on ship propulsion. Improved aerodynamics contributes to reduced fuel consumption during navigation. At the same time the continuous cover minimizes exposure of support structures and equipment and facilitates reinforcement of overall strength to be effective in resisting ice impact load, thus making the system suitable for LNG transportation in icy-water regions.
The new-generation LNG carrier, for which MHI has completed the basic design, measures 288 metres (m) in length overall (LOA), 49.0m in width, 26.0m in depth and 11.5m in draft. The ship has a total tank cargo capacity of 155,000 cubic metres (cbm) using four Moss-type tanks. The ship is projected to respond to anticipated growth in demand for ships in the New Panamax category.
Compared with conventional Moss-type LNG carriers of the same size, the EXTREM has the capacity to transport 8,000 cbm more LNG by employing stretched Moss tanks and its steel hull structure is about 5 percent lighter in weight. The depth of the ship has also been reduced by 1 metre for improved compatibility with major terminals in Japan and other countries.
For its main power plant, the EXTREM adopts MHI's "Ultra Steam Turbine Plant" (UST), a new turbine plant which achieves higher thermal efficiency through effective use of thermal energy by reheating steam. Together with downsizing, weight reduction and hull line improvement, the new ship is said to achieve a substantial
20 percent reduction in fuel consumption compared to conventional ships.
MHI points out that Moss-type LNG carriers are widely used because of the advantages they offer in terms of high tank structure reliability and strength against possible liquid sloshing inside the tank - features which enable the vessel to achieve swift departure from the pier in case of an emergency and permit safe voyages through rough waters.
"The EXTREM combines these advantages of Moss-type carriers with energy-saving, environmentally friendly features and higher LNG cargo transport capacity. MHI thus looks to its new-generation LNG carrier as a sure leader in tomorrow's shipping industry, and the company aims to conduct its marketing activities aggressively," MHI said.
