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HANSA 10-2018

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Schiffstechnik | Ship

Schiffstechnik | Ship Technology Is there a future for large diesel engines? The efficient transport of goods in large ships powered by large-bore diesel engines has become a central factor of globalisation. As world trade in the next 40 years is expected to increase by 400% there will be a continued need for reliable and efficient cargo carriers, writes Hans Payer Might the present-day diesel engine be replaced in the future? This was the basic question of the recently held 5 th Rostock Large Engine Symposium, addressing the field of tension of emissions, fuels and cost. 21 papers were presented largely in light of the increased requirements to protect the environment, on new developments of large slow speed, medium and high speed diesel engines for marine applications and on detailed developments of techniques and devices to cope. The pressure to decrease the environmental impact today very quickly leads to the popular opinion: »let’s do it with an electric drive«. In fact, in shipping this is a possibility for smaller ships on limited routes in coastal waters and is being implemented already today. A large containership, however, will likely never be e-powered. The power requirement is so large over a journey of many days that with today’s technologies a good part of the carrying capacity of the ship would be used up carrying the batteries; not to mention the cost of sufficiently large power packs. Harbours worldwide would have to be equipped to recharge the battery-packs. And this is sensible only if the electricity on land comes from renewable sources, which will be the case only for a limited number of ports. The efficiency of ships can be further increased for slow, medium and highspeed engines through complex modern technologies and optimisation of the total engine system. Improvements are possible through better exhaust heat recovery (up to 5%), efficiency optimization (5%) as well as integrated propulsion with dedicated power and energy management (up to 15-25%). System integration und -optimization are for instance done by AVL with the tool »Cruise M«, where complex powering systems can be simulated in real time and the best configuration of the system and the best suited components can be determined. Source: OMT Common rail injector for low speed engine Early system analyses included the main engines and the attached systems within the vessel. Today, there is a clear trend towards considering the total ship within its operating domain. This requires taking into account the environmental conditions and the hydrodynamics of the ship. And this will require electronic supervision worldwide. New fuels and advanced injectors The maximum content of sulfur in heavy fuel oils will need to be reduced to 0.5% worldwide in 2020. This will be a significant step towards the use of clean fuels also for large marine diesel engines. The current developments of highly efficient combustion processes combined with exhaust treatment will make clean and well suited fuels indispensable in the future. Whether there will still be a use for heavy fuel oils, only time will show. Synthetically improved fuels tailored to specific requirements of modern engines, such as »e-fuels« or »Power-to-X« on the basis of renewable energy, are expected to come in use more widely. In the drive towards higher efficiency and more flexibility regarding fuels, OMT has further developed their common rail injector family particularly for the use in low speed engines. The aim is to develop engines with more flexibility regarding the use of liquid and gaseous fuels keeping operating cost to acceptable levels. Common rail systems offer that extra flexibility controlling combustion. This assists in reducing cylinder pollutants and facilitate the control of pollutant abatement systems. Additionally, they have the potential to facilitate the design of dual fuel systems. By performing the function of both, the micro pilot injection for gas injection to dual fuel engines as well as full power injection in the diesel mode the total engine cost is reduced. 68 HANSA International Maritime Journal – 155. Jahrgang – 2018 – Nr. 10

Schiffstechnik | Ship Technology The injectors for low speed engines were developed on the basis of experience with injectors for medium speed engines. Improvements, such as increasing robustness and leveraging scale economy were derived for both types of injectors. Two models of injectors for low speed engines cover the bore size range from 300 to 600 mm. Specific features were added to the basic design, such as a circulation valve that allows keeping the injector warm during engine standstill by passing warm low-pressure fuel through the injector. A slide valve design of the needle tip, which cuts off the connection between sac volume and spray holes, prevents fuel dripping in the combustion chamber between injections. This reduces smoke and hydrocarbon emissions. With the control valve placed very close to the injector needle together with the fuel accumulator in the injector enables it to deliver very precise and repeatable pilot injections. Long-term trials in laboratories, on test bed engines as well as in pilot projects aboard selected ships have proved the advantages and reliability of this new system. Experience so far demonstrated a reduction in fuel consumption especially at partial load and possible simplifications to the layout of the engine, which will reduce operation and maintenance cost for the total life cycle. Safe nuclear energy, perhaps? Marco Dekena and Hinrich Mohr from AVL List stated: »Our future cannot solely consist of electro-mobility.« Electric propulsion of intercontinental shipping is simply not feasible. A sufficiently dense alternative fuel source is not in sight. Nuclear power propulsion of ships is no doubt still connected with unacceptable risk. Perhaps we’ll have safe nuclear energy in small units at our disposal some time in the future, but we are still far away from this now. Only the poorly informed can believe the days of diesel propulsion for ships are numbered. The conference showed clearly that the marine world is convinced of the future of large engines for the propulsion of ships. Engineers of all ages are highly motivated to improve the efficiency and reduce the environmental footprint of shipping. This includes further optimisation of the propulsion systems in all details as well as a whole system, making sensible use of the possibilities of the digital age, and significant improvements in the fuels of the future. n Dual-fuel engines (like this Wärtsilä 34DF) offer flexibility in the future Mit über 130-jähriger Tradition ist FahnenFleck Ihr Spezialist für die Ausstattung mit: Schiffsflaggen Nationalflaggen Fahnenmasten Displays Beachflags Eventausstattung Wir beraten Sie gern: Tel. 040 - 300 934 - 0 Mehr Infos: Source: Wärtsilä HANSA International Maritime Journal – 155. Jahrgang – 2018 – Nr. 10 69

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