Wartsila 46F - Page 83

500 cStViscosity for dimensioning of electric motor
Heater, booster unit (1E02)
The heater must be able to maintain a fuel viscosity of 14 cSt at maximum fuel consumption,
with fuel of the specified grade and a given day tank temperature (required viscosity at injection
pumps stated in Technical data). When operating on high viscosity fuels, the fuel temperature
at the engine inlet may not exceed 135°C however.
The power of the heater is to be controlled by a viscosimeter. The set-point of the viscosimeter
shall be somewhat lower than the required viscosity at the injection pumps to compensate
for heat losses in the pipes. A thermostat should be fitted as a backup to the viscosity control.
To avoid cracking of the fuel the surface temperature in the heater must not be too high. The
heat transfer rate in relation to the surface area must not exceed 1.5 W/cm
2
.
The required heater capacity can be estimated with the following formula:
where:
heater capacity (kW)P =
total fuel consumption at full output + 15% margin [l/h]Q =
temperature rise in heater [°C]ΔT =
Viscosimeter, booster unit (1I02)
The heater is to be controlled by a viscosimeter. The viscosimeter should be of a design that
can withstand the pressure peaks caused by the injection pumps of the diesel engine.
Design data:
0...50 cStOperating range
180°CDesign temperature
4 MPa (40 bar)Design pressure
6.3.6.5 Pump and filter unit (1N03)
When more than two engines are connected to the same feeder/booster unit, a circulation
pump (1P12) must be installed before each engine. The circulation pump (1P12) and the safety
filter (1F03) can be combined in a pump and filter unit (1N03). A safety filter is always required.
There must be a by-pass line over the pump to permit circulation of fuel through the engine
also in case the pump is stopped. The diameter of the pipe between the filter and the engine
should be the same size as between the feeder/booster unit and the pump and filter unit.
Circulation pump (1P12)
The purpose of the circulation pump is to ensure equal circulation through all engines and to
maitain the required pressure at the injection pumps.
Design data:
LFO:2cSt HFO:20cStCapacity
DAAB605814 6-27
6. Fuel Oil SystemWärtsilä 46F Product Guide