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Wärtsilä has announced that it has strengthened its offering in the mid-size, low-speed engine sector by adding new 62- and 72-bore low-speed engines to its portfolio using technology designed to enable operators to lower fuel consumption.

These standardised engines are said to offer high propulsion efficiency, reliability, and optimised total cost of ownership for customers in the bulker, tanker, and feeder container markets.

Both engines employ Wärtsilä low-speed technology, and incorporate electronically-controlled fuel supply and control. The 62-bore engine with a bore of 620 mm has four to eight cylinders, each with an output of 2660 kW at a speed of 97-103 rpm. The 72-bore engine has a bore of 720 mm and four to eight cylinders, each with an output of 3610 kW at a speed of 84-89 rpm.

Development work on the new engines has been carried out at Wärtsilä's Low-Speed Competence Centre in Winterthur, Switzerland following a feasibility study in 2010.

The first 62-bore engine will be available for delivery in September 2013 and the first 72-bore engine will be available approximately one year later.

The new engines are designed to serve the merchant fleet in vessels that use smaller engines. The primary targets for the 62-bore engine are smaller capesize bulk carriers, Panamax bulk carriers, Aframax tankers, and handysize container vessels, while capesize bulk carriers, Suezmax tankers, and Sub-Panamax to Panamax container vessels are ideal applications for the 72-bore engines.

"At launch, the new engines are IMO Tier II compatible and available with IMO Tier III solutions. The design philosophy and main engine parameters have been selected to give high levels of reliability as the first priority. At the same time, the design enables the lowest possible manufacturing costs," said Lars Anderson, Vice President, Merchant, Wärtsilä Ship Power.

Since the engine design parameters also allow for a compact engine room, shipyards can now use the same engine room module for various vessel types, from bulk carriers and tankers to container vessels. Furthermore, owners can rationalise their crew training and spares for the entire fleet.

Benefits for ship owners, operators, and shipyards

The new engines are said to offer significant benefits to both shipowners and operators. The stroke/bore ratio offers internal efficiency with a gain of 1-2 percent compared to current engines, and depending on the vessel type, the lower engine speeds make it possible to improve propulsion efficiency by 2-6 percent, according to Wärtsilä.

The layout fields of both engines are extended to maintain output, while allowing an increased shaft speed. The extended fields offer added flexibility to select the most efficient propeller speed for the lowest daily fuel consumption, and the most economic propulsion equipment, for a wide varity of vessel types. This concept was first applied successfully with the Wärtsilä RTA/RT-flex 82 bore engines.

The new engine designs also offer de-rating possibilities, which can further improve either the engine's internal efficiency or its propulsion efficiency, or both. Overall efficiency gains of 5-8 percent at vessel level can therefore be expected. As this directly reduces the emission levels of carbon dioxide (CO2), sulphur oxides (SOx), and nitrogen oxides (NOx), it will be easier for shipyards to satisfy EEDI (Energy Efficiency Design Index) requirements.

Wärtsilä's common-rail technology

Wärtsilä is a leader in common-rail technology for electronically-controlled low-speed marine engines. These engines incorporate the latest electronically-controlled common-rail technology for fuel injection, valve actuation, engine starting, and cylinder lubrication with direct benefits to shipowners.

"Wärtsilä's common-rail technology plays a key role in enabling shipowners to meet the challenges of higher fuel costs," Wärtsilä said.

The technology provides a high degree of flexibility in engine settings designed to give lower fuel consumption, very low minimum running speeds, smokeless operation at all running speeds, and outstanding control of exhaust emissions.

The regulation of engine operation provided by the Wärtsilä electronically controlled engine system allows for good manoeuvring capabilities and the lowest possible operating speed, for example, during canal passages and port entrance.