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
Annex VI of the MARPOL 73/78 convention entered into force on 19 May 2005. All Wärtsilä engines included in this booklet comply with the NOX limits specified in the Annex.
The exhaust emissions regulations in Annex VI of the MARPOL 73/78 convention are now referred to as IMO Tier I. In October 2008, the Marine Environment Protection Committee (MEPC) of IMO adopted 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 limits for engines installed in ships constructed on or after 1 January 2011 will be reduced, according to a speed-dependent function, about 20% from the presently valid IMO Tier I levels.
Under IMO Tier III, the NOX emission limit for engines installed in ships constructed on or after 1 January 2016 will be reduced, according to a speeddependent function, 80% from the presently valid IMO Tier I levels (see chart), when the ship is operating in a designated Emission Control Area. Outside designated Emission Control Areas 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 the 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.
Certification means that the NOX emissions of the engines 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, and optimisation of the fuel injection equipment. This has reduced the emissions with only a marginal decrease in efficiency, or none at all. As per today, over 50 engines have been delivered complying with the DNV Clean Design NOX requirement.
