Wärtsilä’s solutions are customized to specific ship design and operational requirements to ensure maximum efficiency, reliability and environmental performance over the entire lifecycle of the installation. Examples of Wärtsilä’s achievements in environmental care are RT-flex engines, dual-fuel engines for LNG carriers and environmentally friendly sterntube sealing systems.
IMO NOX EMISSIONS AND WÄRTSILÄ ENGINES
The Annex VI of the MARPOL 73/78 convention entered into force on 19 May 2005. All Wärtsilä engines included in the portfolio comply with the NOX limit specified in the Annex.
The exhaust emissions regulations in the Annex VI of the MARPOL 73/78 convention are now referred to as IMO Tier I. In April 2008, the Marine Environment Protection Committee (MEPC) of IMO approved proposed amendments to the MARPOL Annex VI regulations. These specify further NOX emission limits to be known as IMO Tier II and Tier III. Under IMO Tier II, the NOX emission limit for engines installed in ships constructed on or after 1 January 2011 would be reduced, according a speed-dependent function, about 20% below the actual IMO Tier I (see chart).
Under IMO Tier III, the NOX emission limit for engines installed in ships constructed on or after 1 January 2016 would be reduced, according a speeddependent function, 80% below the actual IMO Tier I (see chart), when the ship is operating in a designated Emission Control Area. Outside a designated Emission Control Area, Tier II limits apply.
Wärtsilä will adapt its engines to comply with the new upcoming NOX emission regulations.
CLEAN DESIGN CERTIFICATION FOR MEDIUM-SPEED ENGINES
Wärtsilä engines have achieved Clean Design certification as defined by Det Norske Veritas (DNV) classification society. So far, the Wärtsilä 20, Wärtsilä 32 and Wärtsilä 34DF engine types have been delivered with the certificate, and in the future all other Wärtsilä engine types will follow.
For the engines, the certification means that the NOX emissions are approximately 20% lower than the current IMO Tier 1 level. This is another step in our continuing, proactive development of engines for lower exhaust emissions and reduced environmental impact.
The emission levels have been lowered largely by reducing the maximum combustion temperatures. This has involved a combination of measures: Early inlet valve closing (Miller timing), optimisation of the combustion chamber, andoptimisation of the fuel injection equipment. In this way, the emissions have been reduced with a marginal or no decrease in effi ciency. As per today, over 50 engines have been delivered complying with the DNV Clean Design NOX requirement.
