The Wärtsilä NOR units are selective catalytic reduction (SCR) converters that will meet the stringent requirements of IMO Tier III emissions control regulations with regard to NOx reduction. The NOR units are able to reduce NOx emissions to a level of 1.5 g/kWh. IMO Tier III is expected to come into force in 2016. The Selective Catalytic Reduction (SCR) process reduces NOx emissions to harmless substances normally found in the air that we breathe.

The SCR product for Wärtsilä medium-speed engines is named Nitrogen Oxide Reducer (NOR). An SCR installation consists basically of a reactor, which is the core of the installation, an injection unit and a compact unit, where the urea solution is pumped and dosed for the desired NOX reduction. This compact unit is provided with dedicated control cabinet. As alternative, the urea solution can be fed with separated pumping unit and dosing unit, which are controlled by a separated control unit.

The new SCR product range caters for the needs of all four-stroke engines in Wärtsilä's portfolio and can be used for both newbuild and retrofits. The SCR control system is seamlessly integrated with the Wärtsilä engine control system and the units come with a completed prefabricated ancillary system offering the following features:

• Combined silencer and SCR unit tailored for Wärtsilä engines
• Modular design enabling SCR retrofit
• Minimized size
• NOx reduction 85-95%
• Sound attenuation 25-35 dB(A)