WÄRTSILÄ 46F Series, Product Manual

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HFO pipes shall be properly insulated. If the viscosity of the fuel is 180 cSt/50°C or higher,
the pipes must be equipped with trace heating. It shall be possible to shut off the heating of
the pipes when operating on MDF (trace heating to be grouped logically).
6.3.6.1 Starting and stopping
The engine can be started and stopped on HFO provided that the engine and the fuel system
are pre-heated to operating temperature. The fuel must be continuously circulated also through
a stopped engine in order to maintain the operating temperature. Changeover to MDF for start
and stop is not required.
Prior to overhaul or shutdown of the external system the engine fuel system shall be flushed
and filled with MDF.
6.3.6.2 Changeover from HFO to MDF
The control sequence and the equipment for changing fuel during operation must ensure a
smooth change in fuel temperature and viscosity. When MDF is fed through the HFO
feeder/booster unit, the volume in the system is sufficient to ensure a reasonably smooth
transfer.
When there are separate circulating pumps for MDF, then the fuel change should be performed
with the HFO feeder/booster unit before switching over to the MDF circulating pumps. As
mentioned earlier, sustained operation on MDF usually requires a fuel oil cooler. The viscosity
at the engine shall not drop below the minimum limit stated in chapter Technical data.
6.3.6.3 Number of engines in the same system
When the fuel feed unit serves a single Wärtsilä 46DF engine only, a feeder/booster unit (1N01)
shall be installed. On multiple installation of W46DF engines, it’s possible to install a single
feeder/booster unit (1N01) followed by one individual circulation pump before each W46DF
engine (1P12). It’s anyhow recommended to consider redundancy of feeder/booster unit (1N01)
for higher installation reliability.
In addition the following guidelines apply:
Twin screw vessels with two engines should have a separate fuel circuit for each propeller
shaft. Twin screw vessels with four engines should have the engines on the same shaft
connected to different fuel circuits. One engine from each shaft can be connected to the same
circuit.
Main engines and auxiliary engines should preferably have separate feeder/booster units
(1N01). Regardless of special arrangements it is not recommended to supply more than
maximum two main engines and two auxiliary engines, or one main engine and three auxiliary
engines from the same fuel feed unit. Pilot line of multiple W46DF engines can have a single
pilot fuel feed pump (1P13), at condition that any flow balancing distribution is prevented.
6.3.6.4 Feeder/booster unit (1N01)
A completely assembled feeder/booster unit can be supplied. This unit comprises the following
equipment:
●
Two suction strainers
●
Two fuel feed pumps of screw type, equipped with built-on safety valves and electric motors
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One pressure control/overflow valve
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One pressurized de-aeration tank, equipped with a level switch operated vent valve
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Two circulating pumps, same type as the fuel feed pumps
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Two heaters, steam, electric or thermal oil (one heater in operation, the other as spare)
●
One automatic back-flushing filter with by-pass filter
DAAB605814 6-23
6. Fuel Oil System Wärtsilä 46F Product Guide