Classification societies approve two designs for LNG fueled containershipsWritten by Nick Blenkey
Development of large, LNG-fueled containerships moving ahead. Classification societies DNV and Bureau Veritas have each given approval in principle to designs for such vessels. Kawasaki Heavy Industries has gotten approval for a 9,000 TEU ship from DNV. Bureau Veritas has given approval in principle for a 14,000 TEU basic design developed in a joint industry project between Korea’s Daewoo Shipbuilding & Marine Engineering, liner major CMA-CGM and Bureau Veritas.
Both designs use prismatic tanks to store the LNG, the rectangular shape of the prismatic tanks utilizes space more efficiently than cylindrical tanks.
In the case of the Kawasaki design, the LNG is stored in prismatic low pressure insulated tanks (Type B) with the Kawasaki Panel System being used for heat insulation in order to reduce the rate of evaporation of LNG.
DNV says that B-type tanks produce evaporating LNG continuously which must be used for propulsion or auxiliaries. Reefer containers will consume the boil off in port eliminating any emission of LNG to air, as well as eliminating the need for cold ironing.
KHI obtained DNV Approval in Principle for both the gas supply system of the vessel and the LNG fuel tanks. Next, KHI plans to perform a safety assessment of the vessel with DNV.
The LNG fuel tank and diesel oil tanks are located under the forward superstructure minimizing the loss of cargo space. The design criteria for ships using LNG as fuel are currently being studied by IMO (BLG). The location of LNG tanks under the accommodation has been a subject for discussion in the industry. DNV plays an active role in these discussions.
“It is important to understand the environmental imperatives that shipowners face, but it is also important to recognize that, in reality, the uptake of new technologies is a balance between risk and business need. Together, DNV and KHI have struck just the right balance with this vessel,” says Tor Svensen, COO at DNV.
The Kawasaki design features:
(1) A twin island design maximizing cargo space available for loading containers.
(2) A two stroke dual-fuel main engine which is electronically controlled with a high combustion efficiency coupled with a hull form optimized for safety and fuel efficiency.
(3) The engine may be equipped with an exhaust gas recirculation system (EGR) which satisfies IMO Tier-3 requirements for voyages in North American and European Emission Control Areas (ECAs).
Principal particulars of the 9,000 TEU Kawasaki LNG-fuelled container vessel are:
Length overall 308 m
Breadth 48.4 m
Draft 14.5 m
LNG fuel tank 7,000 cu.m
The basic design approved by Bureau Veritas is for a 365.5 m loa vessel with a design draft of 14 m and a design speed of 24 knots. In the dual fuel configuration a 22,490 cu m LNG prismatic tank would be installed under the forward accommodations, and there would be a 4,430 cu m capacity bunker tank aft for heavy fuel oil . The LNG tank would be a Daewoo patent ACT-IB Aluminum Cargo Tank – IMO type B independent LNG tank with PUF(Poly-Urethane Foam) panel type insulation.Paris-headquartered classification society
“The market will determine when these ships can be ordered and built, but this is a real milestone as for the first time we have a fully worked and approved design for a main line ultra-large containership running on LNG,” says Jean-Francois Segretain, deputy technical director, Bureau Veritas. “After an in depth HAZID analysis we can say with confidence that there are no technical or safety barriers to introducing LNG as a fuel for long-haul large containerships. Major operational savings are deliverable, combined with very much lower air emissions. And the key feature of this design is that the vessel can also run on HFO if required, increasing flexibility in the period before LNG bunkering is widely available.”
The 14,000 TEU vessel will be powered by an ME-GI (MAN Electronic – Gas Injection) 2-stroke dual fuel engine made by MAN Diesel. This delivers the highest efficiency among existing propulsion systems and works by simultaneous dual burning of HFO and LNG. In minimum fuel and maximum gas mode around 10 percent of the fuel is oil, providing overall CO2 emission reductions in the order of 23 per cent and SOX reductions of 92 per cent.
The main engine would be rated at MCR 72,285 kW and the vessel would have a range of 25,000 miles if fully bunkered.
“Compared to the same ship with a conventional fuel power plant there will be extra capital cost for the engine and for the LNG tank and gas handling system, and there is a loss of cargo space equivalent to 438 teu to make room for the gas tank and equipment,” says Mr. Segretain. “But the extra capital cost and the loss of earnings on a theoretical full ship are more than offset by the fuel economies and lower emissions of this design.”
January 19, 2012
January 19, 2012
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