Wartsila ?31DF Series Product Manual page 113

Wärtsilä 31DF Product Guide
If the engines are to be operated on MDF only, heating of the fuel is normally not necessary.
In such case it is sufficient to install the equipment listed below. Some of the equipment listed
below is also to be installed in the MDF part of a HFO fuel oil system.
6.4.5.1 Circulation pump, MDF (1P03)
The circulation pump maintains the pressure at the high pressure pumps and circulates the
fuel in the system. It is recommended to use a screw pump as circulation pump. A suction
strainer with a fineness of 0.5 mm should be installed before each pump. There must be a
positive static pressure of about 30 kPa on the suction side of the pump.
Design data:
Design pressure
Max. total pressure (safety valve)
Nominal pressure
Design temperature
Viscosity for dimensioning of electric
motor
6.4.5.2 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.
In installations where MDF is fed directly from the MDF tank (1T06) to the circulation pump,
a suction strainer (1F07) with a fineness of 0.5 mm shall be installed to protect the circulation
pump. The suction strainer can be common for all circulation pumps.
Design data:
Capacity
Design pressure
Max. total pressure (safety valve)
Design temperature
Pressure for dimensioning of electric motor (ΔP):
Viscosity for dimensioning of electric motor
6.4.5.3 Flow meter, MDF (1I03)
If required, a flow meter is used for monitoring of the fuel consumption. The total resistance
of the flow meter and the suction strainer must be small enough to ensure a positive static
pressure of about 30 kPa on the suction side of the circulation pump. There should be a
by-pass line around the consumption meter, which opens automatically in case of excessive
pressure drop.
6.4.5.4 Automatic filter (1F04)
It is recommended to select an automatic filter with a manually cleaned filter in the bypass
line. The coarser by-pass filter is only intended for temporary use, while the automatic filter is
maintained.
Design data:
DBAE248994
1.6 MPa (16 bar)
1.2 MPa (12 bar)
see chapter "Technical Data"
50°C
90 cSt
3
3.6 m /h per high pressure pump on the engine
1.6 MPa (16 bar)
1.2 MPa (12 bar)
150°C
If MDF is fed directly from day tank: 0.12 MPa (1.2 bar)
If all fuel is fed through feeder/booster unit: 0.6 MPa (6 bar)
500 cSt
6. Fuel Oil System
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