Wartsila ?31DF Series Product Manual page 108

6. Fuel Oil System
6.4.4.4 Separator pre-heater (1E01)
The pre-heater is dimensioned according to the feed pump capacity and a given settling tank
temperature.
The surface temperature in the heater must not be too high in order to avoid cracking of the
fuel. The temperature control must be able to maintain the fuel temperature within ± 2°C.
Recommended fuel temperature after the heater depends on the viscosity, but it is typically
98°C for HFO and 20...40°C for MDF. The optimum operating temperature is defined by the
sperarator manufacturer.
The required minimum capacity of the heater is:
where:
For heavy fuels ΔT = 48°C can be used, i.e. a settling tank temperature of 50°C. Fuels having
a viscosity higher than 5 cSt at 50°C require pre-heating before the separator.
The heaters to be provided with safety valves and drain pipes to a leakage tank (so that the
possible leakage can be detected).
6.4.4.5 Separator (1S01/1S02)
Based on a separation time of 23 or 23.5 h/day, the service throughput Q [l/h] of the separator
can be estimated with the formula:
where:
The flow rates recommended for the separator and the grade of fuel must not be exceeded.
The lower the flow rate the better the separation efficiency.
Sample valves must be placed before and after the separator.
6.4.4.6 MDF separator in HFO installations (1S02)
A separator for MDF is recommended also for installations operating primarily on HFO. The
MDF separator can be a smaller size dedicated MDF separator, or a stand-by HFO separator
used for MDF.
6-24
P = heater capacity [kW]
Q = capacity of the separator feed pump [l/h]
ΔT = temperature rise in heater [°C]
P = max. continuous rating of the diesel engine(s) [kW]
b = specific fuel consumption + 15% safety margin [g/kWh]
ρ = density of the fuel [kg/m
t = daily separating time for self cleaning separator [h] (usually = 23 h or 23.5 h)
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Wärtsilä 31DF Product Guide
DBAE248994