Marine Power: First Order for High-Pressure SCR for Two-Stroke Engines
MAN Energy Solutions announced the first order for its SCR-HP (Selective Catalytic Reduction – High Pressure) product.
Mitsui (MES) has ordered 3 × SCR-HP (cluster 3) units in connection with the building of three 87,000-dwt bulk carriers for the Ocean 21 Holdings .
Each ship is to be powered by a single MAN B&W 6S46ME-B8.5 low-speed engine delivering 9,900 kW at 84 rpm, and aspirated by an MAN TCA66 turbocharger. Importantly, the engines will meet IMO Tier III emission standards.
MAN Energy Solutions introduced SCR-HP along with its licensee, MES, in 2017. While new to the two-stroke sector, the system is well proven and 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 of all bore sizes 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.
The MAN SCR-HP Series
The SCR-HP comes in six frame sizes, covering engines up to 25 MW with one reactor for the entire exhaust stream. Larger engines will require two reactors, which can be arranged in a multi-setup similar to turbochargers.
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 100 systems are already in the order book awaiting Scheme B certification.