Schiffstechnik | Ship
Schiffstechnik | Ship Technology Abstract: Large combustion engines, high pressure for development More stringent emission legislation and an increasing public interest for environmentally friendly propulsion concepts are dominating the research and development activities of engine manufacturers and suppliers. With the introduction of IMO Tier III emission limits for marine diesel engines must be drastically reduced. At the same time, substential regulations on the fuel sector are to be respected. To meet these challenges new technological concepts and control strategies are required. Against this background the 6 th Rostock Large Engine Symposium constitutes a forum for a professional dialog between legislation, researchers, developers and operators of large engines. erfahrung und Optimierungspotenziale werden zur Diskussion stehen. Noch fahren aber viele Schiffe mit flüssigen Kraftstoffen. Mit der Einführung des globalen Schwefelgrenzwertes von 0,50% produzieren Raffinerien Kraftstoffe, die so bisher nicht in der Schifffahrt zum Einsatz kamen. Instabilität, Kompatibilität, hohe Cat Fines oder ungünstige Verbrennungseigenschaften werden erwartet, dazu werden auf der RGMT Analyseergebnisse vorgestellt. Der Themenbereich Kraftstoffeinspritzung erhält auch in diesem Jahr auf dem Symposium in mehreren Vorträgen Raum. So geht es beispielsweise um Entwicklungsansätze für Piloteinspritzdüsen, die für den Mikro-Pilotverbrennungsprozess eingesetzt werden. Wasserstoff, Methanol, Abgas digital controls and softWare mechanical governors combustion / ignition turbocharger With a full range of innovative products, We are meeting your future requirements today WWW.WoodWard.com air / exhaust floW control spare parts COMMON-RAIL systems lp gas systems HFO COMMONrail systems pump line noZZle systems DUAL-FUEL systems WWW.lorange.com more efficiency, loWer emissions Außerdem geht es um Wasserstoff/Methanol- und Wasserstoff/Diesel-Doppelbrennstoff-Verbrennungssysteme für nachhaltige maritime Anwendungen. Ein Paper beschäftigt sich mit der Wasserstoff-Direkteinspritzung, die als sicher und effizient, aber als technisch sehr anspruchsvoll gilt. Ein weiterer Schwerpunkt der RGMT wird auf Abgasnachbehandlungstechnologie wie Oxidationskatalysatoren und VWT-SCR sowie auf Partikelfiltern liegen. Es wird vorgestellt, wie mit Hilfe von Nachbehandlungssystemen, Motor- Tuning und Biokraftstoff die aktuellen Emissionsgrenzwerte noch unterschritten werden können. Auch die Digitalisierung kommt nicht zu kurz, »Lokale Intelligenz« und Internet-of-Things (IoT)-Geräte bringen neue Funktionalitäten und Optionen. Das beleuchten Vorträge zu intelligenten Injektoren und Datenanalyse-Algorithmen. Mit der immer weiteren Optimierung der Motorarchitektur beschäftigen sich Experten in Vorträgen zu numerischer und experimenteller Temperaturfeldanalyse und zu Simulationstechniken und Modellierung zur Reduzierung von Reibungsverlusten. fs 6. Rostocker Großmotorentagung 3.-4. September 2020 Rostock, Radisson Blu Hotel Programm und Anmeldung unter https://rgmt.de/ 36 HANSA – International Maritime Journal 09 | 2020
Schiffstechnik | Ship Technology MAN managing methane slip Using LNG as a ship fuel is a step in preparing engines for use of low-carbon fuels on the way to carbon-neutrality. The escape of unburnt methane raises questions on the climate benefits of LNG that are being addressed by engine makers like MAN Energy Solutions Without countermeasures, there are several routes by which unburnt methane can escape from both two- and four-stroke gasburning engines via the engine exhaust as well as the crankcase ventilation, a phenomenon called »methane slip«. LNG is typically 85 % to 95 % CH4, a greenhouse gas considerably more potent than CO2. As MAN lays out in a recent Whitepaper entitled »Managing methane slip«, the phenomenon is most prevalent on gas-burning engines operating according to the Otto combustion process, where gas fuel and air are mixed homogenously prior to ignition and combustion. It affects engines in which the premixed fuel and air are ignited by a spark-plug (spark-ignited (SI) gas engines) as well as dual-fuel (DF) engines where a liquid fuel »pilot« initiates ignition of the air-gas mixture. MAN’s ME-GI two-stroke dual-fuel engines are already achieving very low levels of unburnt methane emission due to operation on the Diesel combustion principle. This is explained by the fact that in the ME-GI two-stroke DF engines, the gaseous fuel is injected into the compressed charge air around top dead centre and only slightly after the liquid fuel pilot, when the pilot has already ignited. This ensures complete combustion with maximised heat release. Since the gaseous fuel only enters the cylinder after the exhaust valve has closed and ignites immediately, there is no opportunity for methane to escape during cylinder scavenging. In addition, virtually no unburnt methane is trapped in crevice volumes, such as the »top land« between the piston and cylinder liner. Methane slip levels lie in a range from 0.2 – 0.3 g/kWh over the ME-GI engines’ load range. The countermeasures devised and under investigation at MAN’s technical department for four-stroke engines involve all the major aspects of internal engine design: control of engine operation; combustion processes and their control; basic engine architecture. MAN’s four-stroke SI gas and DF engines operate on the Otto BUREAU VERITAS SA Zweigniederlassung Hamburg Marine Department Veritaskai 1, 21079 Hamburg Tel.: +49 40 23625-0 Fax: +49 40 2 36 25-620 E-Mail: ger_cha@de.bureauveritas.com Visit us on: www.bureauveritas.de www.veristar.com principle, where gaseous fuel is pre-mixed with air before ignition. This mixture is compressed and ignited by a spark-plug or liquid fuel pilot injection and is thus in the cylinder for all of the induction and compression strokes and part of the power stroke. As four-stroke engines rely much more for gas exchange on inlet and exhaust valves, there are increased opportunities for the gas to evade combustion. An important line of attack centres the reduction in the overlap of inlet and exhaust valve openings and the timing of gas admission. Valve overlap creates an unavoidable period during the inlet stroke of a four-stroke engine when both inlet and exhaust valves are open in order to »scavenge« the cylinder. Minimising the overlap reduces the time in which air/gas mixture can reach the exhaust port, while control of the timing and duration of gas admission from electrically-controlled valves in the inlet ports limits the time that gas can enter the cylinder during exhaust valve opening. In terms of engine architecture, a successful approach is the reduction of »crevice volumes« in the combustion chamber, i.e. areas where pockets of unburnt gas can be trapped and not be reached by the flame.ED Marine | Industry | Inspection & In-Service Verification | Health, Safety & Environment | Construction Certification | Consumer Products Services | Government Services & International Trade HANSA – International Maritime Journal 09 | 2020 37
