MAN Energy Solutions offers both SCR and EGR as NOx solutions within two-stroke sector
MAN Energy Solutions has announced the very first order for its SCR-HP (Selective Catalytic Reduction – High Pressure) product. Mitsui E&S Machinery (MES-M) has ordered 3 × SCR-HP (cluster 3) units in connection with the building of three 87k-dwt bulk carriers. The engines will accordingly meet IMO Tier III emission standards.
MAN Energy Solutions introduced SCR-HP along with licensee, MES-M, in 2017. The development of the new system is based on MAN’s in-house competence with four-stroke engines, for which it can already reference more than 650,000 operating hours.
The MAN SCR-HP is available for two-stroke engines and reduces – through internal catalytic reaction – NOx exhaust emissions to IMO Tier III limits. With specially developed honeycombs and honeycomb materials, as well as an integrated mixing unit, the overall size of the reactor has been drastically reduced compared to typical market designs and its medium-speed counterpart.
Exhaust gas recirculation (EGR) is an internal engine process that prevents the formation of NOx by controlling the combustion process, while Selective Catalytic Reduction (SCR) is an after-treatment method that uses a catalyst and an additive to reduce the NOx generated by the combustion process.
The SCR-HP comes in six frame sizes, covering engines up to 25 MW with one reactor for the entire exhaust stream.
The SCR-HP system consists of the reactor – including mixing unit, urea injection lance, honeycombs and soot blowers – along with a module-based supply system, as well as the reactor’s control unit that communicates with the engine-control system.
The SCR-HP system is available for Scheme A and Scheme B classification approval. Scheme A approval includes a certification of the complete system on the engine test bed, SCR and original piping.
Approval via Scheme B reduces complexity for all involved parties. The engine is tested in IMO Tier II mode on a test bed. MAN Energy Solutions then models the SCR system and calculates the Tier III mode. On the parent engine, this mode is certified on board during engine commissioning. This Scheme B approval is confirmed by several classification societies and reduces the test demands required of the engine licensee. The process is well established in MAN’s medium-speed sector, and over 170 systems are already in the order book awaiting Scheme B certification.
