Rocks & mirror
Encyclopedia of Marine and Energy Technology

Combustion Air Saturation System (CASS)


NOx suppression technique developed by Wärtsilä, whereby combustion air is humidified before entering the engine cylinder. In a CASS installation, special Hi-Fog nozzles lead water directly into the air stream after the turbocharger in the form of very small droplets which evaporate very fast in an environment of more than 200°C and 75m/s air velocity. Further heat for evaporation is provided by the air cooler (but acting now as a heater), producing in combustion air with a humidity of around 60g/kg air. With this an amount of water, it is possible to secure NOx levels of less than 3g/kWh.