Abstract
IMO NOx emission regulation Tier 3 will come into force and will require NOx reductions in marine low speed two-stroke diesel engines below a cycle value of 3.4 g/kWh in Emission Control Areas. To comply with this regulation, a combined EGR (exhaust gas recirculation) & WEF (water emulsified fuel) system has been developed to effective reduce NOx with minimum penalty in fuel oil consumption. The test engine was a Kawasaki-MAN B&W 2S50ME-C.
The turbocharger cut-out system and VT (variable turbine nozzle area) turbocharger incorporated with the EGR system enabled the reduction of NOx with minimal impact on fuel oil consumption.
A wet scrubber which is also incorporated with the system removed SOx and PM in the re-circulating gas, thus preventing corrosion and contamination in the scavenging air system during EGR operation. Water treatment system which is one of the most important systems for EGR was developed to effectively remove PM from the washing water out of the scrubber using a special compact settling tank.
