Design data:
Capacity:
5 x the total consumption of the connected engines
- without circulation pumps (1P12)
15% more than total capacity of all circulation pumps
- with circulation pumps (1P12)
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
Pump and filter unit (1N03)
When more than one engine is 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. With a common
circulation pump for several engines, the fuel flow will be divided according to the pressure distribution in
the system (which also tends to change over time) and the control valve on the engine has a very flat
pressure versus flow curve.
Product Guide Wärtsilä 34DF - 3/2012
65
Product Guide
6. Fuel System
