Page 52: of Maritime Reporter Magazine (April 2004)

Gas Ships secondary fuel.

The Wartsila 50DF

Developed from Wiirtsila's very suc- cessful type 46 diesel engines, the

Wartsila 50DF engines have cylinder dimensions of 500 mm bore by 580 mm piston stroke. Available in configura- tions with six, eight and nine cylinders in line, and 12, 16 and 18 cylinders Vee- form, the Wartsila 50DF engines devel- op 950 kW per cylinder MCR at 500 or 514 rev/min for 50Hz and 60Hz electric- ity generation respectively.

Gas fuel is supplied at a low pressure (less than five bar) to the engines. In gas mode, the Wartsila 50DF engines oper- ate according to the lean-burn Otto process. Gas is admitted into the air inlet channels of the individual cylinders dur- ing the intake stroke to give a lean, pre- 6L50DF mixed air-gas mixture in the engine combustion chambers. Reliable ignition is obtained by injecting a small quantity of diesel oil directly into the combustion chambers as pilot fuel which ignites by compression ignition as in a convention- al diesel engine. The Wartsila 50DF engines use a 'micro-pilot' injection with less than one per cent of the fuel energy being required as liquid fuel at nominal load. Electronic control closely regu- lates the 'micro-pilot' injection system and air-gas ratio to keep each cylinder at its correct operating point between the knock and misfiring limits.

Circle 40 on Reader Service Card

The preceding was excerpted in part from a paper by Glenn Mattas. Sales, Wartsila

Finland Oy and Barend Thijssen, Solutions,

Wartsila Corporation.

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Circle 298 on Reader Service Card

Maritime Reporter & Engineering News