Wartsila ?31DF Series Product Manual page 177

Wärtsilä 31DF Product Guide
The engine can run in backup operating mode in case the engine has been started with the
blackout start input active or a pilot trip has occurred. A transfer to gas operating mode can
only be done after a combustion check, which is done by restarting the engine.
A leakage test on the GVU is automatically done before each gas transfer.
Fig 14-6
14.2.2.3 Points for consideration when selecting fuels
When selecting the fuel operating mode for the engine, or before transferring between operating
modes, the operator should consider the following:
● To prevent an overload of the gas supply system, transfer one engine at a time to gas
operating mode
● Before a transfer command to gas operating mode is given to an engine, the PMS or
operator must ensure that the other engines have enough 'spinning reserve' during the
transfers. This because the engine may need to be unloaded below the upper transfer limit
before transferring
● If engine load is within the transfer window, the engine will be able to switch fuels without
unloading
● Whilst an engine is transferring, the starting and stopping of heavy electric consumers
should be avoided
14.2.3 Stop, shutdown and emergency stop
14.2.3.1 Stop mode
Before stopping the engine, the control system shall first unload the engine slowly (if the engine
is loaded), and after that open the generator breaker and send a stop signal to the engine.
DBAE248994
Transfer sequence from liquid to gas mode passes through LFO operation to
engusre back-up fuel system is flushed clean of HFO. HFO to LFO transfer time
is depend on the design of external fuel system and HFO viscosity. Usually HFO
to LFO transfer takes about 30 minutes.
Operating modes are load dependent
NOTE
14. Automation System
14-9