DPF+SCR ultra low emission solution for medium speed diesel engines

Already today engine emissions from medium speed engines operating in protected areas or used for special applications are subject to ambitious emission reduction requirements. The driving force behind such requirements is not necessarily from regulatory bodies, but rather commercial, stemming from green operators or investors. Publicly exposed applications like passenger ships or the growing offshore wind turbine industry are two good examples. The emission targets are derived from the most stringent non-road mobile machinery emission rules. Unlike in IMO regulation, not only nitrogen oxides (NOX) but also carbon monoxide (CO), hydrocarbons (HC), particulate matter on mass (PM) and number (PN) base are limited due to their health and environmental impact. Building on our previously presented study to optimize a combined medium speed engine andaftertreatment system package for best fuel consumption and emission performance, we present our testing results of combining the ABC DZC engine family (1-4 MW) with a Hug Engineering DPF+SCR system yielding unprecedented ultra low emissions. On the engine testbed, a 2 MW ABC DZC series engine was combined with a modular Hug exhaust gas aftertreatment system consisting of a diesel particulate filter (DPF) with active regeneration and a selective catalytic reduction (SCR) system with the possibility to include also an oxidation catalyst. Inorder to achieve the challenging emission requirements as well as to optimize overall operating costs, the engine was de-tuned from its original 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 further below. 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. Detailed investigations during our test campaigns concerning sub 23 nm particle emissions and black carbonrevealed even cleaner exhaust than seen today by DF LNG engines. The presented assembly is the first MW-sized medium speed engine to be certified according to EU Stage V and for the new Bureau Veritas notation “ultra low emission vessel” (ULEV). 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 is one of the next steps to reduce the overall impact for the environment. 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 presented as well.