Exhaust gas treatment system and method, as well as ship comprising, and use of, such a system

System for treatment of engine exhaust gas from an engine, which engine exhaust gas has a temperature of between T1 and T2, the system comprising a SCR reactor for converting NOx contained in a medium containing the engine exhaust gas into N2 and H2O, the SCR reactor having an inlet for receiving the medium and an outlet for outputting the NOx reduced medium, further comprising a mixing unit and a first boiler unit, the first boiler unit having a first outlet for outputting boiler exhaust gas from the first boiler unit, which boiler exhaust gas has a temperature of T3 or more, T3>T1, the mixing unit being arranged to mix the engine exhaust gas with the boiler exhaust gas to produce said medium, the mixing unit having a first inlet communicating with the engine for receiving the engine exhaust gas, a second inlet communicating with the first outlet of the first boiler unit for receiving the boiler exhaust gas and an outlet for outputting said medium, the outlet of the mixing unit communicating with the inlet of the SCR reactor.