View non-flash version
January 2013 www.sname.org/sname/mt reciprocating engine. Smaller craft have used natural gas as fuel, but the rst commercial vessel with dedi- cated LNG is considered to be the Glutra , a car ferry operated by Fjord 1 on the west coast of Norway since 2000. Norway has been a leader in LNG fuel for marine transportation with the rst LNG-fueled platform sup- ply vessel, Viking Energy , delivered to Eidesvik Oshore in 2003 (see the vessel report in the October 2011 issue of (mt) ). e Norwegian Coast Guard has operated three LNG-fueled patrol vessels since 2010. Other countries are breaking new ground, with modern LNG carriers having been constructed with dual-fuel diesel-elec- tric engines to enable use of the LNG for fuel. Finlands Viking Line is slated to take delivery of an LNG-fueled cruise ship, Viking Grace , in 2013. According to a sur- vey by Marintek, 12 LNG-fueled ships were on order as of April 2012. The conversion e conversion of Bit Viking was the rst conversion of a diesel-powered ship to run on dual-fuel (LNG or diesel). In 2010, Statoil contacted Tarbit about the possibility of converting the ship to run on LNG. e parties agreed to move forward with the idea and engaged Wärtsilä during summer 2010. Conversion to LNG bunker fuel creates a win-win situation,? says Statoils Karl Brekke. Its commercially attractive and it provides signicant environmental gain in the form of lower fuel consump- tion and reduced environmental emissions.? Wärtsilä has been a leader in LNG-fueled marine propulsion systems. e fact that Wärtsilä had sup- plied the original engines for Bit Viking provided a good starting point for the engine conversion. Before the start of the conversion work, Wärtsilä had con- verted 40 diesel engines on land to dual-fuel service. One of these 50DF engines had accumulated more than 40,000 hours of operation after conversion, so condence was high that conversion of the marine engines would be successful. e actual modication scope included honing out the cylinder bores from a diameter of 46 cm to 50 cm; replacing the cylinder heads; installing new cylinder liners and anti-polishing rings; tting new upper sec- tions to the engines connecting rods; and installing dual-needle injection valves. Components that were added to the engines included a gas rail pipe and gas admission valves, a pilot fuel system (pilot fuel oil l- ter, common-rail piping, and pilot fuel oil pumps), and exhaust gas waste gates. In addition, the following addi- tions were made: new engine turbochargers for dual-fuel (DF) operation, installing camshaft components for DF Miller-valve timing, and installing and commissioning a new UNIC engine control system. The conversion work included the installation of Wärtsiläs LNGPac system (two gas storage tanks e fact that Wärtsilä had supplied the original engines for Bit Viking provided a good starting point for the engine conversion. SPECIFICATIONS: BIT VIKING OWNERTarbit Shipping BUILDERShanghai Edward Shipbuilding DELIVERED2007?converted to dual-fuel service in 2011 DESIGN AND CONVERSION Wärtsilä Ship Design/Wärtsilä Corporation FLAG SwedishCLASS GL* 100A5 E3 ESP IW NAV-OC Chemical Tanker Type-2. Oil Tanker with Double Hull MC E3 AUT * INERT RP2-50 %. MAIN PARTICULARS DEADWEIGHT 24.783 MT LENGTH OVER ALL 177.03 m LENGTH BETWEEN PERPENDICULARS 166.99 m BEAM26.30 m DEPTH, MOLDED 12.80 m DRAFT 9.70 m SERVICE SPEED Approximately 16 knots TYPE OF VESSEL Product and chemical tanker, IMO Class 2 MAIN ENGINES2 x WÄRTSILÄ 6L50DF 5,700 kW at 500 rpm Vessel Report continued