Mitsubishi Heavy Industries, Ltd. has received an order from Nippon Yusen Kabushiki Kaisha for a liquefied natural gas (LNG) carrier capable of marked reductions in fuel consumption. The vessel is the first of its kind to adopt “MHI Ultra Steam Turbine Plant”, a new turbine plant which enables approximately 15% higher fuel efficiency than conventional steam turbine plants, a feat achieved through efficient utilization of thermal energy by reheating steam. The LNG carrier is scheduled for completion and delivery in 2014.
The about 123,000 gross tonnage Eco-LNG carrier on order will measure 288 meters (m) in overall length, 49m in breadth and 26.8m in depth. It will have capacity to carry a total of 145,400m3 of LNG using four MOSS type spherical storage tanks, whose safety and reliability have been confirmed through wide use in LNG carriers. The ship is designed for optimal environmental friendliness: in addition to reduced gas emissions through lower fuel consumption enabled by the UST, it features a ballast water treatment system and capability to use low sulfur fuel oil.
The UST, a marine propulsion steam turbine plant utilizing reheated steam, is a technology commercialized by MHI; it adopts a medium-pressure turbine, in addition to high- and low-pressure turbines. After the steam from the boiler drives the high-pressure turbine, the exhausted steam is returned to the boiler and reheated for driving to the medium-pressure turbine, and subsequently the low-pressure turbine. Compared with conventional steam turbine plants, the UST facilitates cascade the utilization of thermal energy and enables reductions in fuel consumption. Steam turbines are reliable in constant and stable operation due to high reliability of plant, and with the UST further improvement in fuel efficiency from conventional steam turbines has been realized.
Presently, as part of measures to prevent global warming, reductions in CO2 emissions are vigorously being sought also in the area of international maritime transportation, and the International Maritime Organization (IMO) has been preparing the framework of a CO2 emissions convention. Against this backdrop, MHI has accorded priority to the development of high-value-added vessels addressing CO2 reduction needs. The UST system was commercialized for ships that are in frequent service and require stable operation.
Going forward MHI will focus on development of its “Eco-ships” and customer expansion, leveraging its strength in handling ships and major marine-use machinery plus its leading-edge technologies in energy-saving and environment related areas.
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Source: Mitsubishi Heavy Industries, March 1, 2011;