The new Wärtsilä 46DF engine has been specifically developed for the high-output market and is fuel flexible as well as power flexible with 1045 kW or 1145 kW cylinder power options.
Compactness and reduced weight are the key attractions of the medium-speed engine, giving ship designers the option of increasing a new vessel’s revenue-earning capacity to get the most efficient propeller speed through mechanical (reduction gearing), or through diesel-electric transmissions.
With the cruise ship, ferry, LNG carrier and offshore vessel markets for this type of engine in mind, the 46F engine design is based on the well proven Wärtsilä 46F engine, popular since the early 2000s, but with the advantage of being able to use natural gas, heavy fuel oil (HFO), or marine diesel oil (MDO) bunker fuel.
The Wärtsilä 46DF extends Wärtsilä’s dual-fuel engine family by covering the power range from 6.2 MW to 18.3 MW at 600 rpm.
• Cylinder bore 460 mm
• Piston stroke 580 mm
• Cylinder output 1045/1145 kW/cyl
• Engine speed 600 rpm
• Mean effective pressure 21.7, 23.8 bar
Wärtsilä 46DF engine: Image courtesy of Wärtsilä
Fuel flexibility & automation
Wärtsilä’s proven dual-fuel technology enables a choice between gas and liquid fuels, with a switch between the two according to cost, availability, and local environmental regulations. Wärtsilä say that the switch between fuel types is made without loss of power or speed. The engine automation adapts automatically to the relevant fuel selection, both in normal and emergency modes.
In gas mode, the natural gas is fed to the engine at low pressure. This facilitates a simpler and space saving engine room configuration, while providing easier and faster maintenance activities.
The engine’s gas piping is double-walled as standard, and the advanced integrated automation system enables enhanced safety and local monitoring, which leads to safer and more reliable operations under all conditions.The complete built-in automation minimizes the need for external controls, thus saving engine control room space.
The Wärtsilä 46DF is designed for a broad range of marine applications and the engine can be optimized for constant speed diesel electric operation. It also meets the need for direct drive main engine propulsion, operating at either constant speed or along a combinator curve.
Fuel savings for LNG carriers
For LNG carrier applications, the engine builders say that the 46DF can offer fuel savings of as much as 20 tons/day compared to the first introduced DF engines. With up to 14 fewer cylinders installed, the overall lifecycle installation costs are significantly and positively impacted by roughly 1000 USD/day.
Exhaust gas emissions
When operating in gas mode, the Wärtsilä 46DF engine is already compliant with IMO Tier III regulations without any secondary exhaust gas purification systems. In liquid fuel oil mode, the Wärtsilä dual-fuel engines are fully compliant with the IMO Tier II exhaust emission regulations set out in Annex VI of the MARPOL 73/78 convention.