Man B&W S50ME-B9.3-TII, Project Manual

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MAN B&W 12.07
Page 1 of 2
MAN Diesel
MAN B&W MC/MCC, ME/MEC/ME-B/-GI engines 198 40 567.3
Components for Jacket Cooling Water System
The sensor is to be located at the outlet from the
main engine, and the temperature level must be
adjustable in the range of 7090 °C.
Jacket water preheater
When a preheater, see Fig. 12.05.01, is installed in
the jacket cooling water system, its water flow, and
thus the preheater pump capacity, should be about
10% of the jacket water main pump capacity.
Based on experience, it is recommended that the
pressure drop across the preheater should be
approx. 0.2 bar. The preheater pump and main
pump should be electrically interlocked to avoid
the risk of simultaneous operation.
The preheater capacity depends on the required
preheating time and the required temperature
increase of the engine jacket water. The tempera-
ture and time relations are shown in Fig. 12.08.01.
In general, a temperature increase of about 35 °C
(from 15 °C to 50 °C) is required, and a preheating
time of 12 hours requires a preheater capacity of
about 1% of the engine`s nominal MCR power.
Deaerating tank
Design and dimensions of the deaerating tank
are shown in Fig. 12.07.01 ‘Deaerating tank‘ and
the corresponding alarm device is shown in Fig.
12.07.02 ‘Deaerating tank, alarm device‘.
Expansion tank
The total expansion tank volume has to be ap-
proximate 10% of the total jacket cooling water
amount in the system.
Fresh water treatment
MAN Diesel & Turbo’s recommendations for treat-
ment of the jacket water/freshwater are available
on request.
Jacket water cooling pump
The pumps are to be of the centrifugal type.
Jacket water flow ............... see ‘List of Capacities’
Pump head ...................................................3.0 bar
Delivery pressure ...................depends on position
of expansion tank
Test pressure ...................... according to class rule
Working temperature, ............. 80 °C, max. 100 °C
The flow capacity must be within a range from
100 to 110% of the capacity stated.
The stated capacities cover the main engine only.
The pump head of the pumps is to be determined
based on the total actual pressure drop across
the cooling water system.
Freshwater generator
If a generator is installed in the ship for produc-
tion of freshwater by utilising the heat in the jacket
water cooling system it should be noted that the
actual available heat in the jacket water system is
lower than indicated by the heat dissipation figures
given in the ‘List of Capacities‘. This is because
the latter figures are used for dimensioning the
jacket water cooler and hence incorporate a safety
margin which can be needed when the engine is
operating under conditions such as, e.g. overload.
Normally, this margin is 10% at nominal MCR.
The calculation of the heat actually available at
specified MCR for a derated diesel engine is stat-
ed in Chapter 6 ‘List of Capacities‘.
For illustration of installation of fresh water gen-
erator see Fig. 12.05.01.
Jacket water thermostatic valve
The temperature control system is equipped with
a threeway valve mounted as a diverting valve,
which bypass all or part of the jacket water
around the jacket water cooler.