Marine Log - March 2008 - (Page 24)

DIESELPOWER ICE CLASS TANKERS regulations. It recently inked a deal with Shell Marine Products for the delivery of between 350,000 to 400,000 tonnes of low sulfur fuel oil. The yearly average maximum sulfur content will be 1.05%. WWL says its self-imposed environmental policy has paid off, enabling it to cut its SOx emissions by over a third; it has saved 75,550 tons of sulphur dioxide emissions between 2001 and 2006—more than the amount of sulphur dioxide that London emitted into the atmosphere over a similar period. Between 2000 and 2006, WWL also reduced the fuel consumption per transported unit by 11.5%, thereby cutting emissions of CO2 and NOx, as well as SOx, into the atmosphere. WWL also expects the refined hull lines of the new RO/RO carriers to reduce fuel-oil consumption and exhaustgas emissions. Exhaust-gas energy will also be recovered to generate all electrical power requirements at sea. Rendering of the low-speed, electronically controlled 7L70ME-C8 main engine, showing scale of engine to the average size man meaning that engine overhauls can be performed in connection with scheduled dry dockings. ELECTRONICALLY CONTROLLED ENGINES WILL BE THE NORM Engine manufacturer Caterpillar thinks that electronically controlled engines will become the norm in shipping. It invested some $500 million in the development of its ACERT technology. Back in 2000, Caterpillar Motoren identified three emission levels for the MaK marine product in order to cope with short to midterm emission regulations. These were a base line IMO engine, which fulfils MARPOL 73/78, Annex VI, an IMO-compliant engine with invisible smoke emissions and a Low Emission Engine (LEE) which meets the expected NOx emission range of IMO II and is also invisible in smoke. In addition, this strategy favors inside-theengine means because of their clear advantage with respect to cost, complexity and maintenance. LEE FOR LOW NOX The key issue for low NOx emissions, says Caterpillar, is to increase the compression ratio of the base engine. Ten years ago, a compression ratio of 11-12 was standard, for IMO I the ratio was raised to 14-15 and for IMO II ratios of 17 will be needed. Another cornerstone of the MaK LEE concept is the Miller Cycle, i.e. modification of the engine’s valve timing to achieve cooler combustion. For IMO I only a small Miller effect of 5% was utilised, however, IMO II requires a Miller effect of 20%. This is a big challenge for the turbocharger, which has to provide boost ratios of 5 in order to maintain today’s Mean Effective Pressure (BMEP) values. By combining increased compression ratio and the Miller effect, NOx emissions can be reduced by some 30% without sacrificing engine efficiency (BSFC). However, such a simple LEE engine would suffer from poor load pick-up at idle and emit visible soot at part load. Because of this, the MaK LEE concept uses a “flexible camshaft” (see photo on p. 25) to enable both low NOx emissions, excellent load pick up and invisible soot at all loads. TANKER RETROFIT WITH LEE STANDARD Caterpillar Motoren performed extensive simulation and prototyping of the MaK LEE technology in 2001-2003. In cooperation with Sweden’s Furetank Rederi AB, Cat agreed to convert the Additionally, a 1,100-kW frequency converted PTO has been chosen as power supplement for parallel operation with the turbo generator (maximum output 1,200 kW). This is for use when the sea-load demands more power than can be met by the turbo generator alone. This enables optimal usage of the main engine’s power capacity and increases its overall efficiency, while simultaneously reducing CO 2 , NOx, SOx and FOC emissions. The electronically controlled MAN Diesel engine extends the Time Between Overhauls (TBO), while improving the vessel’s maneuverability. MAN Diesel says that based on operator experience thus far, the TBO is about 32,000 hours or about five years for ME engines— 24 MARINE LOG MARCH 2008 www.marinelog.com http://www.abb.us http://www.abb.us http://www.marinelog.com

Table of Contents Feed for the Digital Edition of Marine Log - March 2008

Marine Log - March 2008 Contents Editorial Second Thoughts Update Inside Washington Navy's Toughest Battle Building Future Fleet Less Fuel, Lower Emissions A New Generation of Mariners Training for the Future LNG Security: Resources Needed Models of Perfection Tech News Newsmakers Contracts Events Infodirect Website Directory ML Marketplace Opinion

Marine Log - March 2008

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