WÄRTSILÄ WARTSILA 20, Product Manual, Page: 70 / 178

Circulation pump, booster unit (1P06)
The purpose of this pump is to circulate the fuel in the system and to maintain the required
pressure at the injection pumps, which is stated in the chapter Technical data. By circulating
the fuel in the system it also maintains correct viscosity, and keeps the piping and the injection
pumps at operating temperature.
Design data:
5 x the total consumption of the connected engines Capacity
1.6 MPa (16 bar) Design pressure
1.0 MPa (10 bar) Max. total pressure (safety valve)
150°C Design temperature
500 cSt Viscosity 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 15% margin [l/h] Q =
temperature rise in heater [°C]
Δ
T =
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 cSt Operating range
180°C Design temperature
4 MPa (40 bar) Design pressure
6-28 Wärtsilä 20 Product Guide - a13 - 6 September 2016
Wärtsilä 20 Product Guide 6. Fuel Oil System