Wärtsilä strengthens hand in hotly-contested sector

30 Nov 2011
Wärtsilä has given a new edge to competition in the 320mm-bore category of the medium-speed market with a more powerful version of the W32 type

Wärtsilä has given a new edge to competition in the 320mm-bore category of the medium-speed market with a more powerful version of the W32 type

Representing a further major stage in the evolution of its 320mm-bore medium-speed engine, Wartsila’s popular W32 series has been augmented by new models offering a 16% power advance over the earlier engine design.

David Tinsley writes: With the first production engines rolled-out this year, the new variants’ maximum rating of 580kW/ per cylinder at 750rpm has strengthened Wärtsilä’s hand in one of the most competitive segments of the marine engine business. Released in six, eight and nine-cylinder in-line formats and 12- and 16-cylinder vee-form configurations, the revised W32 confers maximum power concentrations in the 3,480kW to 9,280kW range. The design in its preceding 500kW/cyl type serves the 3,000-9,000kW band, up to 18-cylinder layout. Notwithstanding the substantial hike in output, the latest models have unchanged external dimensions, making for a high power density.

Suited to both direct mechanical drive and diesel-electric systems, and as an auxiliary engine, the extra compactness of the new generation is likely to increase the appeal of the 320mm-bore series, not least in the offshore market. The W32 already spans a very wide field of application for propulsion duties, as it does in all vessel categories where high auxiliary load is required.

Mean effective pressure has been upped from 24.9bar in the 500kW/cyl engines to 28.9bar in the 580kW/cyl versions, and maximum combustion pressure has been raised to 230bar. The other main design changes include increased pressure in the single turbocharger system, a new cylinder head configuration, common to that of the W34SG gas engine, plus a reinforced engine block and crankshaft, and new, high-strength pistons. Although of conventional type, the fuel injection system is of increased pressure and output. Common-rail fuel injection is offered as an option.

The IMO Tier II-compliant engine is able to operate economically on fuels with an ultra-low sulphur content (less than 0.1% sulphur), as will apply in sulphur emission-controlled areas. It can also be equipped with a selective catalytic reduction (SCR) plant, such as the proprietary nitrogen oxide reducer (NOR), which can reduce NOx (oxides of nitrogen) emissions by up to 95%. By such means, the machinery will fulfil IMO Tier III requirements.

The Wartsila 32 is equipped with a variable inlet valve closure (VIC) unit, allowing early inlet valve closure at high load, which in turn enables NOx levels to be minimised and fuel consumption to be reduced. Good part load and transient performance is conferred by switching to late inlet valve closure.

Suited to a range of fuels, the ingestion properties are such that reliable operation is promised on even the poorest quality heavy fuel. The engine has been designed for overhaul intervals of up to 24,000 hours.

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