Low Speed Diesel Engines

1Rendez-vous du Monde Maritime – 11 mars 2015

Rendez-vous du Monde Maritime


Avantages/InconvénientsGaz Naturel


Propulsions DisponiblesUtilisant le Gaz Naturel Comme Carburant


Steam turbine vs T/DFDE Engines

Benefits•Higher efficiency compared to steam propulsion (but lower compared to slow speed diesel options) •Higher availability of experienced crew comparing to steam turbine•High propulsion redundancy (with back up engine)•Reduced emissions

Disadvantages:• Higher capital cost TFDE• Higher maintenance as a result of more

moving parts, higher speed and more cylinders

• About 10 or 12% efficiency loss in the electric power generation process

• Sensitive to gas quality: knocking with automatic load reduction

• Crew member are not trained to operate electrical equipment and a large part of failure need experimented makers

• Maintenance: scheduled overhaul more stringent (Dry Dock issues) & expensive


Propulsions DisponiblesUtilisant le Gaz Naturel Comme Carburant


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Intake ofair and gas

Compression ofair and gas

Ignition bypilot diesel fuel

Otto principle

Low-pressure gas admission 4 to 6 barg

Pilot diesel injection

Power 2,5 MW to 17,5 MW

Gas mode: •Ex. •In. •Ex. •In.•Ex. •In.

Intake ofair

Compression ofair

Injection ofdiesel fuel

Diesel principle

Diesel injection

Diesel mode:Ex. In. Ex. In.Ex. In.

Dual-fuel engine operating principle

© Wärtsilä

Présentateur

Commentaires de présentation

Les moteurs deux temps et quatre temps fonctionnent sur la base du cycle thermodynamique d’OTTO, qui consiste en deux phases isentropiques (réversibles adiabatiques), la compression et la détente intercalées entre deux phases à volume constant, la combustion et l’échappement. Lorsqu’ils fonctionnent en mode gaz, un mélange pauvre air-gaz carburant est admis en provenance de la turbosoufflante, dans la chambre de combustion de chaque cylindre à basse pression, (inférieure à 5 bars) par une vanne d’admission gaz. Le mélange est enflammé par une faible quantité de carburant pilote (Marine Diesel Oil), qui représente moins de 1% de la consommation à charge nominale. Suivant les fabricants, les injecteurs gaz et du carburant pilote peuvent être combinés ou séparés. En mode Diesel, le carburant est injecté à haute pression dans la chambre de combustion de chaque cylindre par une pompe d’injection L’admission du gaz carburant est désactivée alors que celle du carburant pilote reste active pour assurer un allumage fiable lors du passage du mode diesel au mode gaz.


The Diesel dual fuel engines are four stroke engines with either gas (BOG) or diesel as main fuel. The operating principle in gas mode is the lean-burn concept (Otto cycle). A lean-mixture of gas and air is provided to the combustion chamber of each cylinder by individually controlled gas admission valve. The mixture is ignited by a small amount of pilot Diesel fuel.

Dual-fuel engine operating principle


Low Speed Diesel Engines

• The dual-fuel (low-speed) diesel mechanical propulsion is a dual or triple-fuel type like the DFDE capable of burning both the BOG and liquid oil simultaneously.


Diesel / Otto cycle



Benefits• Consumption: about 20% less than for TFDE• Robustness (not sensitive to knocking )• Efficiency• Lower maintenance compare to 4 strokes (maintenance done on board by crew )• conditioning based maintenance: Improve flexibility regarding Dry dock issues• High fuel flexibility

Disadvantages• Safety: Gas Fuel Pressure supply around 300 Bars for MEGI• Compare to DFDE, MEGI & XDF cannot be operated in Gas Mode at low load• No redundancy in gas chain equipment (In case of failure or maintenance, BOG

handling issues)• MEGI & XDF are not proven technology in marine industry• MEGI & XDF engines are not complying with Marpol requirements

• Defeat devices will be required



Gas Turbine

Avantages :

• Poids inférieur (15 t. pour le module LM2500 )• Montée en puissance très rapide• Facilité d'entretien ( échanges standard d'éléments )• Pollution limitée

Inconvénients :

• Consommation spécifique plus élevée que les moteurs diesel (235 g/kWh à 25 °C )

• Sensible à la température ambiante ( LM 2500 : 23000 kW à 25 °C et 21000 kW à 35 °C )

• Volumes importants des conduites d'arrivée d'air et d'échappement des gaz

• chute importante du rendement à charge partielle en particulier pour les machines à simple arbre

• Redondance?


GAZOCEAN, one of the oldest companies specialised in maritimetransportation of liquefied gases and, is a pioneer in the development of LNGcarriers technologies as cargo containment or propulsion systems.

Founded in 1957 by R. Boudet, in 2013, GDF SUEZ LNG (80%) and NYKLine (20%) are the shareholders.

GAZOCEAN is providing Crew ,Technical and Commercial Managementservices for LNG and LPG carriers, Consulting services and Training for theGas Industry.

GAZOCEAN is certified ISO 9001-2008, ISO 14001, ISM, ISPS and integraterequirements of NYK NAV 9000 and OCIMF TMSA in his Quality System.


Pioneer in MaritimeTransportation

of Liquefied Gases

Low Speed Diesel Engines

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