6.2
Operating principles
Wärtsilä 34DF engines are usually installed for dual fuel operation meaning the engine can be run either in
gas or diesel operating mode. The operating mode can be changed while the engine is running, within
certain limits, without interruption of power generation. If the gas supply would fail, the engine will automat-
ically transfer to diesel mode operation (MDF).
6.2.1 Gas mode operation
In gas operating mode the main fuel is natural gas which is injected into the engine at a low pressure. The
gas is ignited by injecting a small amount of pilot diesel fuel (MDF). Gas and pilot fuel injection are solenoid
operated and electronically controlled common rail systems.
6.2.2 Diesel mode operation
In diesel operating mode the engine operates only on liquid fuel oil. MDF or HFO is used as fuel with a
conventional diesel fuel injection system. The MDF pilot injection is always active.
6.2.3 Backup mode operation
The engine control and safety system or the blackout detection system can in some situations transfer the
engine to backup mode operation. In this mode the MDF pilot injection system is not active and operation
longer than 30 minutes (with HFO) or 10 hours (with MDF) may cause clogging of the pilot fuel injection
nozzles.
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Product Guide Wärtsilä 34DF - 3/2012
Product Guide
6. Fuel System
