Electronic low speed engines added
Wärtsilä has increased its offering in the mid-size, low-speed engine sector by adding new 62- and 72-bore low-speed engines with electronic control to its portfolio.
The new range is designed 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's standardised low-speed technology, and incorporate electronically-controlled fuel supply and control.
The 620mm-bore engine has four to eight cylinders, each with an output of 2,660kW at 97-103rpm. The 720mm version will also be produced with four to eight cylinders, each with an output of 3,610kW at 84-89rpm.
The stroke/bore ratio was chosen for good internal efficiency with a gain of 1%-2% compared to current engines, and depending on the vessel type, the lower engine speeds make it possible to improve propulsion efficiency by 2%-6%.
As with the 82-bore engine family, the layout fields of both new engines are extended to maintain output, while allowing an increased shaft speed. The extended fields are said to give flexibility to select the optimum propeller speed for low fuel consumption, across a variety of propulsion systems and vessel types.
The new engine designs also offer de-rating possibilities, which can further improve either internal efficiency or propulsion efficiency, or both. Overall efficiency gains of 5%-8% at vessel level are expected, which Wärtsilä says will help reduce emissions and satisfy EEDI requirements.
Development work on the new engines has been undertaken at Wärtsilä's low-speed competence centre in Winterthur, Switzerland following a feasibility study in 2010. The compay's Asian licensees have been closely involved in the manufacturing process. The first 62-bore engine will be available for delivery in September 2013 and the first 72-bore engine will be available about one year later. All Wärtsilä licensees will have the right to build the new engines.
The design parameters allow for a compact engine room, so shipyards can now use the same engine room module for various vessel types, from bulk carriers and tankers to container vessels. Furthermore, Wärtsilä says that owners will be able to rationalise their crew training and spares for the entire fleet.
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 said to be ideal applications for the 72-bore engines.
"At launch, the new engines are IMO Tier2 compatible and available with IMO Tier 3 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," says Lars Anderson, vice president, merchant, Wärtsilä Ship Power.