MAN Diesel & Turbo presents new high-pressure SCR for two-stroke engines
At an event in Tamano, Japan on April 11th, MAN Diesel & Turbo and its licensee – Mitsui Engineering & Shipbuilding – introduced its new high-pressure Selective Catalytic Reduction system – MAN SCR-HP – to the market in front of a select group of industry invitees, the company said in its press release.
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.
MAN Diesel & Turbo expects to deliver the first system from the beginning of 2018.
The development of the SCR-HP system was based on MAN’s in-house competence with four-stroke engines, for which it can already reference more than 650,000 operating hours. The newly-developed system comes in six frame-sizes, covering up to 25 MW per reactor.
A major milestone in the development of the MAN SCR-HP was reached during the approval certification and engine shop test. The test was carried out in close collaboration with MAN licensee and partner, Mitsui Engineering & Shipbuilding, at its engine works in Tamano under the observation of ClassNK.
MAN Diesel & Turbo offers two alternative methods to meet IMO Tier III NOx requirements for MAN two-stroke engines. The first, exhaust gas recirculation (EGR), is an internal engine process that prevents the formation of NOx by controlling the combustion process. The second method, 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.
After the technical presentation and a demonstration of the new SCR system in operation on an engine test-bed, Ralf Klaunig, Vice President MAN Diesel & Turbo and Head of Turbocharger Sales, spoke to the audience about the product’s next steps and its timeframe for market introduction.
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 Diesel & Turbo 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.