Compact two-stroke SCR gains Class NK approval

Written by Nick Blenkey
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A high pressure SCR (selective catalytic reduction system) said to be the most compact of its type on the market has passed Class NK approval testing.

MAN Energy Solutions first introduced the SCR-HP concept in 2017. The development of the new system is based on MAN’s in-house competence with four-stroke engines, where it can reference more than 650,000 operating hours. The SCR-HP is now being sold under the PBST brand, formed in 2019 through the joining of the MAN Turbocharger and PBS Turbo brands.

The overall size of the reactor has been drastically reduced compared to typical market designs and its medium-speed counterpart.

The SCR-HP system passed its ClassNK approval test at the Makita engine works in Japan. The system is one of four – originally ordered in 2018 and 2019 – for vessels featuring MAN B&W two-stroke engines with two now delivered and the others currently en route to customers.

An MAN B&W 6S46ME-B8.5 engine will power each vessel, with the SCR-HP system making each vessel Tier III-compatible. The first engine was ordered by Kanax Corporation and installed in a newly developed 39,000-dwt bulk carrier built at Shin Kurushima Toyohashi Shipbuilding Co., Ltd.

PBST’s Ralph Klaunig – Vice President of Sales & License Turbochargers & Exhaust Gas Treatment – and MAN Energy Solutions’ Daniel Struckmeier – Head of Exhaust After-treatment – attended the class test in Japan at the invitation of Yu Makita, President at Makita Corporation.

“The results from the engine shop test were quite spectacular with the PBST SCR-HP system able to undercut the currently valid IMO III NOx values of 3.4g/kWh by more than 1g/kWh, which compares very favorably with the rest of the market,” said Klaunig. “Working closely with Makita, just a little over a year passed between landing the first order and the handing over of the engine with the SCR-HP system to the shipyard. Accordingly, I would like to thank Makita for its great cooperation in delivering such a quick turnaround.”

“We express sincere gratitude to everyone involved in this project at MAN and PBST for the excellent support and cooperation which led to the successful launch of the world’s first MAN SCR-HP,” said Yu Makita. “Representatives of our client, Toyohashi Shipyard, were quite satisfied with what we have achieved. Now we are able to offer a strong and environmentally friendly Makita Mitsui MAN-B&W engine, even in the current, tough market.”

MAN’s SCR-HP now being sold under the new PBST brand features specially developed honeycombs and honeycomb materials, along with 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 SCR-HP comes in six frame sizes, covering engines up to 25 MW with one reactor for the entire exhaust stream.

The 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 a reactor control unit that communicates with the engine-control.

SCR-HP on the test bed at Makita engine works
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