The fuel flexible Wärtsilä 46DF engine has been specifically developed for the high-output market segment, including cruise ships and ferries, merchant vessels, LNG carriers and FSRUs (Floating Storage and Regasification Unit), and offshore vessels and platforms, and is capable of operating on natural gas, heavy fuel oil (HFO), or marine diesel oil (MDO).

The 46DF. Click to enlarge.

The engine can smoothly switch from gas fuel to HFO/MDO operation and vice versa without loss of power or speed. The Wärtsilä 46DF design is based on the well-proven and reliable Wärtsilä 46F and Wärtsilä 50DF engine families, which have operated successfully on the market since the early 2000s. Both engines have an outstanding track record, with more than 700 engines in operation and over 9 million running hours experience using Wärtsilä’s leading DF technology.

This fuel flexibility enables reduced operational expenses, compliance with the most stringent emission standards, and full redundancy to ensure uninterrupted operation.

The Wärtsilä 46DF consists of two different versions to meet specific customer needs. In both, the cylinder bore is 460 mm; piston stroke is 580 mm.The high efficiency version offers drastically lower fuel consumption with a per-cylinder power of 1045 kW (1400 hp), while the high power version is capable of a per-cylinder power of 1145 kW (1535 hp) with excellent engine thermal efficiency. Mean effective pressure is 21.7 for the high-efficiency version, 23.8 bar for the high power version.

For LNG carrier applications, the Wärtsilä 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/day.

When operating in gas mode, the Wärtsilä 46DF engine is already compliant with IMO Tier III regulations without any secondary exhaust gas purification systems. When fueled by gas, the sulphur oxide (SO_x) and CO₂ emissions are notably reduced, and smokeless operation is attained. 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.

Since introducing its dual-fuel technology in 1995, the company’s dual-fuel engines have successfully accumulated 10 million running hours in both marine and land-based applications. Today, more than 1,000 Wärtsilä dual-fuel engines have been sold globally.