In 2008, Wärtsilä continued to develop its marine engines to comply with the amended NOx emissions control regulations of IMO Tier II adopted by the IMO (International Marine Organization) for Annex VI of the MARPOL 73/78 convention.
The Wärtsilä 26 engine (16.9 L/cyl; 340 kW/cyl) has been updated to meet EPA Tier II requirements, and the first engines will soon enter service. The engine using distillate fuel oil is the smallest in the company’s portfolio meeting these requirements.
Wärtsilä has introduced its Wärtsilä 34SG gas engine model to the gas compressor market. With outputs of 4050 to 9000 kW these engines offer considerable lifecycle cost benefits in applications such as gas pipelines and gas storage. According to Wärtsilä, for a typical 9000 kW compressor drive installation, the engine driver can be expected to lower lifecycle costs by around 20 to 40%, compared with other prime movers on the market.
For existing, older compressor drives, the cost savings may be even greater. The engines have a full-load efficiency of 46.3%, a 30% speed turndown ratio to 525 r/min, and a 70% torque turndown ratio. Furthermore, both engine efficiency and exhaust emissions remain virtually unchanged throughout the entire load range. NOX emissions remain below the 500 mg/Nm3 dry at 5% O2 level.
The new dual-fuel Wärtsilä 34DF engine, introduced to the market to replace the 32DF is based on the Wärtsilä 32 engine. The new model, the first orders for which were received last month, incorporates the operational experience gained from the Wärtsilä 32DF, but has a 30% higher output than its predecessor. It also incorporates a number of new features, including double
wall gas piping, built-in lubricating oil system components, and a UNIC engine control system. Because of the high efficiency of the lean-burn combustion process inherent to the DF models, emissions are considerably reduced.
The Wärtsilä 46 engine-type is particularly suited for reefer containerships. Although four-stroke diesel engines are not typical to this application, this trend is changing. Reederei-NSB, the Hamburg-based ship owner has selected the engine. Ten Wärtsilä 9L46D medium- speed engines have been delivered for a series of five 2100 TEU containership newbuildings, recently completed at the Aker Ostee shipyard. With the NSB vessels, two four-stroke engines drive a single controllable pitch propeller through a twin-in/single-out reduction gear. Thus, in light ship conditions, vessels can operate on one engine only so less fuel is consumed than with a traditional low-speed engine.
Low-Speed Marine Engines Wärtsilä low-speed engines will comply with the new IMO Tier II limits by applying internal modifications. These will involve combinations of higher-efficiency turbochargers, more efficient scavenge air coolers, adjustment of engine tuning parameters, and further optimized fuel injectors. For RT-flex engines, the flexibility of the common-rail system will allow adjustments to exhaust valve operation, and fuel injection system parameters, as well as injection rate shaping. The RT-flex engines generally have lower fuel consumption with IMO Tier II than corresponding RTA engines.
In May 2008, Wärtsilä inaugurated a new low-speed research engine, the RTX-4 in Winterthur, Switzerland. It is employed in furthering the development of Wärtsilä low-speed marine engines to meet market needs. The RTX- 4 is a four-cylinder two-stroke common- rail engine of 600 mm cylinder bore. Initially it develops 10 160 kW at a nominal speed of 114 r/min. The engine was designed completely afresh to allow for maximum flexibil ity in accommodating new design concepts.
The first of the Wärtsilä 820 mmbore engines have been built, tested, and are now in service. The first RTflex82C engine successfully passed its factory acceptance test in September 2008 at Hyundai Heavy Industries Co Ltd. The first 8RTA82C engine, which was tested in March also by Hyundai, has already been installed in a 4300 TEU container ship. Two engine types of 350 and 400 mm cylinder bore and a power range of 3475 to 9080 kW have been added to the Wärtsilä low-speed engine portfolio.
They are being developed in co-operation with Mitsubishi Heavy Industries Ltd, taking advantage of the strengths of both companies. The first RT-flex35 engine is due for delivery in the first quarter 2011. The engines are available as RT-flex common-rail engines or mechanically controlled RTA engines. Based on the RTA designs, Mitsubishi will develop UEC-LSE series engines. Wärtsilä now has a full portfolio of RTflex common-rail low-speed marine engines from 3475 to 80 080 kW. The flexibility in engine setting possible with electronically-controlled RT-flex common- rail systems, is proving invaluable for the challenges of high bunker prices and tighter emissions control regulations.