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LNG-fuelled vessels increase in popularity NORWAY


N


ORWEGIAN ship owners, consultants, yards, and authorities have for some


years consistently focused on developing the technology of LNG-fuelled vessels. At the same time, classification regulations and an LNG fuelling infrastructure have been developed. The road ferry Glutra has been in operation


since year 2000, while in 2003, two LNG-fuelled platform supply vessels, Viking Energy and Viking Stril, were built for Statoil by Eidesvik Offshore ASA, at Kleven, Ulsteinvik. The main engines for each of these vessels were Wärtsilä 6L32DF dual-fuel units, each rated at 2010kW. The NOx emissions from these offshore


vessels have been reduced by 89%, or 159tonnes per year per vessel, according to the owner. The savings can be utilised by Statoil in its emission quota, which it claims saves the company some US$1 million per year. In addition, CO2


emissions have reduced by


some 20% - or 2157tonnes per year and per vessel, and SOx emissions have reduced 100%. Fuel efficiency of the vessels is claimed to have


improved by 30% due to the LNG energy. The ships consume approximately 7000tonnes of LNG per year. The engineroom on the vessels is divided


into separate fire- and explosion-proof spaces. Around 220m3


walled cylindrical vacuum insulated tank of stainless steel, which has a volume of 234m3


of LNG is stored in a double- .


Refuelling usually takes place once per week. The working pressure is 5.5bar and the temperature of the LNG is -140O


of boil-off gas used as fuel for the engines and


TECHNICAL PARTICULARS VS 493 AVANT LNG


Length, oa…...................................92.20m Breadth............................................21.00m Depth to 1st deck.............................9.60m Deck area.........................................1010m2 Gross tonnage...........Approx 5600tonnes Main engines................4 x Wärtsilä R32DF Propulsion....................................2 x Rolls- Royce Azipull AZP100/M-280


Tunnel thrusters...............2 x Rolls-Royce TT2200PN FP


Speed...........................................15.5knots Crew...........................................25 persons Single berth cabins..................13 persons Double berth cabins..................6 persons Classification..................DNV+1A1, Supply Vessel, SF,EO,DP AUTR, Gas fuelled, LFL*, Oil Rec, Clean Design, COMF- (V3), Ice C


C. The amount


tank pressure is regulated with two water-pipe- heaters. The boil-off gas is fed to the engine at a temperature of 20O


4bar. With a 390kW heater 600m3


freed per hour. The gas systems were supplied by Swedish


company Cryo AB. All the gas pipes between the fuel tank and engineroom are double-walled, and the spaces have gas detectors. The gas components are all made from stainless steel. Currently Aker Yards Brattvaag is finalising


a series of five bigger LNG-fuelled road-ferries for Norwegian road ferry operator Fjord 1.


Avant LNG for Eidesvik In August this year, an LNG-fuelled Avant type PSV will be delivered from West Contractors' Westcon shipyard. The order for this Vik- Sandvik-designed ship was placed by Eidesvik in November 2005. The option for a second vessel was confirmed last autumn, and delivery for this second craft is set for the second quarter of 2008. The vessels will operate under charter for Statoil. This innovative vessel design combines the


features of the Avant design, with the use of dual-fuel. The cargo spaces are placed forward and the crew accommodation aft. Viking Avant, a conventionally-fuelled vessel of this type, was built for the same owner in 2004. The big platform supply vessel has a length


of 92.2m, a breadth of 21.0m, and a gross tonnage of 5600tonnes. The vessel has a crew of 12, working in two shifts, with a resulting


C and with a pressure under gas can be


berth capacity of 25; 13 single berth cabins, and 12 double berth cabins. Four Wärtsilä R32DF dual-fuel generator


packages, each rated at 1950kWe will be fitted. Propulsion will be supplied by a pair of Rolls- Royce azimuthing Azipull thrusters of type AZP 100/M-280 - each with an output power of 2200kW. The two Z-drives are electrically driven, with power supplied by Alconza QD 560 M2-6w asynchronous AC motors, each rated at 2400kW. The vessel will be fitted with a large


complement of deck equipment including: two Karmøy mooring winches; two Karmøy tugger winches of 10tonnes-14tonnes; six Karmøy 3.5tonne cargo lashing winches; one crane of 10tonnes, and one of 3tonnes, both supplied by TTS. Eidesvik claims that the fuelling system


reduces NOx emissions by 89%, ie, 160tonnes per year, and CO2


emissions are reduced by 23%,


compared to operation on marine diesel. This vessel will also serve as testing ground for fuel cell technology, which is under development by Eidesvik Offshore. The vessel, which will receive DP


capabilities, will also be fitted with two 1200kW Rolls-Royce tunnel thrusters forward, plus one additional retractable 880kW thruster. Classification will be carried out by Det


Norske Veritas, which, over the last decade, has performed much work on LNG vessel regulations, alongside the Norwegian authorities and suppliers.


INTERNATIONAL CONFERENCE ON COMPUTER APPLICATIONS IN SHIPBUILDING (ICCSA 2007) 18-20 September 2007, Portsmouth UK


For more information on this event please contact the Conference Department by telephone on +44 207 201 2401 or by e-mail to conference@rina.org.uk


22 SHIP & BOAT INTERNATIONAL MAY/JUNE 2007


Vik-Sandvik's VS 493 Avant-type LNG fuelled offshore supply vessel will operate for Statoil from next autumn.


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