Wärtsilä NOx Reducer (NOR)

The Wärtsilä NOx Reducer (NOR) is an emission after-treatment system based on the Selective Catalytic Reduction (SCR) technology for Nitrogen Oxide (NOx) reduction. The system is compliant with various NOx emission reduction needs, such as the IMO Tier III rules.

The NOR is optimized and validated for Wärtsilä medium speed engines in terms of reliability, flexibility and size. It is available for both newbuild and retrofits and is compatible for operation on both distillate and heavy fuel oils.

The main component of the NOR installation is the Reactor with a soot blowing unit and the catalyst elements. Other modular essential parts of the NOR system are a Urea pump unit, a Urea dosing unit, an Urea Injection and mixing unit, an Air unit and the Control unit which controls the NOR operation by monitoring engine parameters. For the purpose of easy installation, several auxiliary units are centralized, so that same units can be utilized in case of multiple NOR installations.

    Technical diagram
    NOR layout

    Product hologram


    • Arctia Offshore
      The turnkey project involved the fitting of combined Wärtsilä NOx Reducer (NOR) and Oxidation Catalysts (OXI) to the MSV Fennica and MSV Nordica.

      Arctia Offshore

    • Gitte Henning S349
      The propulsion equipment package include a Wärtsilä 9L32 main engine with new design, gear, controllable pitch propeller (CPP), HR Nozzle, Wärtsilä 8L26 auxiliary engine, as well as related equipment – including NOx reducers for both engines.

      Gitte Henning S349

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