Near zero emission medium speed engine for EU Stage V & ULEV

Near zero emissions for large engine operation are a long-term target, which requires advances in several technical fields, such as fuels, engines and exhaust gas aftertreatment. However, today IMO restricts only nitrogen oxides (NO_X) and sulphur oxides (SO_X) emissions for sea going vessels, while carbon monoxide (CO), hydrocarbons (HC), particulate matter on mass (PM) or number (PN) base are not considered. For on shore, in inland water or coastal shipping in the EU and USA, large engines are already exposed to regulation considering all these emission components. Additionally, regional authorities start to foster the compliance of work vessels like tug boats and dredgers with such advanced emission regulation near shore, in harbors or in special low emission zones. Public awareness of engine emission impacts on the environment and health motivate reduction of the visible plume from leisure vessels such as cruise ships, ferries or yachts. Medium speed diesel engines remain the prime technology for power generation and propulsion in industrial marine applications due to their high efficiency, reliable operation even at high operating hours, robust design with little need for service and competitive price. However, recent emission requirements as the ones mentioned above can no longer be achieved by the optimization and adjustment of engine design parameters alone, they need the combination with an advanced emission control system. Anglo Belgian Corporation (ABC) and Hug Engineering engaged in a development project to enable a medium speed diesel engine to run in compliance with EU Stage V emission limits for non-road mobile machinery, outperforming US EPA Tier 4 final marine emission requirements, and thereby enabling the classification according to the ultra-low emission vessel (ULEV) notation for IMO registered ships.On an engine testbed, a 2 MW ABC DZC series engine was combined with a modular Hug exhaust gas aftertreatment system containing a diesel particulate filter (DPF) with active regeneration and a selective catalytic reduction (SCR) system with possibility to include also an oxidation catalyst. In order to achieve the challenging emission requirements as well as to optimize overall operating costs, the engine was de-tuned from its IMO Tier II settings to a fuel efficiency optimized low PM emission setting. This was only possible at the expense of increased engine-out NOX emissions, which were reduced by the SCR system down to EU Stage V levels and beyond. Variations of engine- and aftertreatment-setups were tested on full scale in generator and propeller operation mode cycles, yielding a robust concept to achieve well-below EU Stage V emission limits. For further CO₂ emission reductions beyond the ones achieved via the fuel consumption savings, the entire system was chosen to consist of biofuel- and synthetic-fuel-ready components, which will be one of the next steps.This novel concept of an ultra-low emission medium speed diesel engine was chosen to be implemented as a propulsion and power system into a latest generation wind turbine installation vessel containing 25 MW total installed power which will be briefly presented as well.