WÄRTSILÄ WARTSILA 20, Руководство по эксплуатации продукта

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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 sha ll 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 Changeover to low sulphur fuel
●
Fuel system should allow slow, controlled change in fuel temperature in order to avoid
thermal shock in the injection pumps. The recommended fuel temperature change over
rate at switching is maximum 2 °C / min.
●
Check compatibility when using mixed fuels (clogging filters, separators etc). Wärtsilä
4-stroke engines are normally not sensitive for fuel lubricity and additives are not necessarily
needed.
●
HFO engines starting to alternate between HFO and MDF or LSMDF can typically continue
with the same lubricant as before. Nimonic exhaust valves should be used to avoid hot
corrosion.
●
HFO engines starting to operate continuously on LSHFO can continue using lubricating oil
with a BN of at least 30.
● Engines starting to operate continuously on MDF or LSMDF are recommended to start
using lubricating oil with lower BN 10-20. Exhaust valves with stellite facing should be
used.
●
BN monitoring of lubricating oil should be established in order to prevent operating with
too low BN (increased risk for corrosion).
6.3.6.4 Number of engines in the same system
When the fuel feed unit serves Wärtsilä 20 engines only, maximum three engines should be
connected to the same fuel feed circuit, unless individual circulating pumps before each engine
are installed.
Main engines and auxiliary engines should preferably have separate fuel feed units. Individual
circulating pumps or other special arrangements are often required to have main engines and
auxiliary engines in the same fuel feed circuit. 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.
6-24 Wärtsilä 20 Product Guide - a13 - 6 September 2016
Wärtsilä 20 Product Guide 6. Fuel Oil System