Figure 14.7
Operating modes are load dependent
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
•
When running on gas, the engine load should be kept well above the automatic transfer lower limit
in order to prevent unwanted transfer back to diesel
•
When running several engines on gas, the load level should be kept such that no drop below the
automatic transfer load limit occur when an additional engine is brought on line
•
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
14.2.4
Stop, shutdown and emergency stop
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.
Immediately after the engine stop signal is activated in gas operating mode, the GVU performs gas shut-
off and ventilation. The pilot injection is active during the first part of the deceleration in order to ensure
that all gas remaining in engine is burned.
In case the engine was stopped in gas operating mode the exhaust gas system is ventilated to discharge
any unburned gas, if gas has been utilized within two minutes prior to the stop.
Shutdown mode
Shutdown mode is initiated automatically as a response to measurement signals.
In shutdown mode the clutch/generator breaker is opened immediately without unloading. The actions
following a shutdown are similar to normal engine stop.
Shutdown mode must be reset by the operator and the reason for shutdown must be investigated and
corrected before re-start.
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Product Guide Wärtsilä 34DF - 3/2012
Product Guide
14. Automation System
