With the modular exhaust gas aftertreatment system (EGA), MAN Engines presents its solution for meeting the IMO Tier III and US EPA Tier 4 exhaust gas standards in workboats. The system convinces with its high flexibility and enormous compactness and thus meets the most diverse requirements in professional shipping. The modular EGA allows a wide range of installation variants thanks to variably positionable individual components of the SCR catalytic converter and enables flexible system integration in line with requirements. “By reducing the number of components to just a few, the system retains a high degree of packing density in all variants and thus proves to be the optimum solution for our customers – even in space-critical installation situations,” explains Claus Benzler, Head of Marine MAN Engines.
Furthermore, the basically maintenance-free exhaust gas aftertreatment system impresses not only with its compactness and flexibility, but also with its low weight. Focussing on a few components proves to be the key in this case as well.
Heart of the EGA is an SCR catalytic converter (Selective Catalytic Reduction), with the help of which the nitrogen oxides (NOx) in the exhaust gases are specifically reduced. For this purpose, a 32.5 % urea solution (AdBlue©) is metered into an SCR mixer and continuously injected directly into the exhaust tract. There, the solution reacts with the nitrogen oxides and converts them into water (H2O) and harmless nitrogen (N2). The compressed-air-free SCR injection brings further space advantages and reduces the technical effort as well as the installation volume of the system, which can be installed flexibly in any case.
The modular exhaust gas aftertreatment system from MAN Engines is thus a modern SCR-only system that dispenses with complex exhaust gas recirculation and space-consuming, heavy components such as diesel particulate filters and oxidation catalysts. This saves additional costs and reduces the complexity of the system.
Together with the optimised combustion of the MAN engines, the SCR catalytic converter is sufficient to comply with both IMO Tier III and US EPA Tier 4 emission standards. By using the EGA, the specific fuel consumption of the engines – which are already known for their fuel efficiency – could be reduced by up to a further 8 % while maintaining the same power output. MAN Engines’ engineers have thus succeeded in developing an efficient, simple and lightweight, yet robust and versatile exhaust gas aftertreatment system.
This is made possible by the know-how of MAN Truck & Bus AG, which has been successfully using SCR systems in the Group’s own trucks in large-scale production since 2006. In addition, MAN Engines benefits from the installation experience gained in the agricultural and industrial sectors, where the technology has already been used for in-line and V engines since 2015. The EGA is also proving its practicality in ongoing field trials for workboats.
This means that MAN engines for workboats are ready for the IMO Tier III emission standard (within NOx ECA North Sea ECA & Baltic Sea ECA), which will be mandatory from 2021. This standard prescribes a reduction of nitrogen oxides (NOx), depending on the maximum operating speed of the engine, by approximately 70 %, compared to IMO Tier II. Instead of the previous 7.7 g/kWh, only 2.0 g/kWh will be permissible in future.
The US Tier 4 emission standard has been valid since 1st October 2017 for all US flagged workboats with a power output of more than 600 kW (816 HP) per combustion engine. Compared to US Tier 3, the law prescribes a reduction of nitrogen oxides (NOx) by almost 68 % to 1.8 g/kWh and by almost 64 % to 0.04 g/kWh for particle emissions for diesel engines in workboats.
With its 12-cylinder engines, MAN Engines currently offers a consistent performance portfolio for the US Tier 4 and IMO Tier III exhaust gas stages. This range will be continuously supplemented by further performance levels.