Jacket Cooling Water Temperature Control - Man B&W S50ME-B9.3-TII Project Manual

MAN B&W

Jacket Cooling Water Temperature Control

When using a normal freshwater generator of the
singleeffect vacuum evaporator type, the fresh-
water production - based on the available jacket
cooling water heat Qjw - may, for guidance, be
estimated as 0.03 t/24h per 1 kW heat, i.e.:
M = 0.03 x Qjw t/24h 15%/0%
fw
where
M is the freshwater production in tons per 24
fw
hours
and
Q is to be stated in kW
jw
If necessary, all the actually available jacket cool-
ing water heat may be used provided that a spe-
cial temperature control system ensures that the
Freshwater generator system
Condensator
Produced
freshwater
Evaporator
Valve A: ensures that T < 80° C
jw
Valve B: ensures that T > 80 – 5° C = 75° C
jw
Valve B and the corresponding bypass may be omitted if, for example, the freshwater generator is equipped with an automatic
start/stop function for too low jacket cooling water temperature
If necessary, all the actually available jacket cooling water heat may be utilised provided that a special temperature control system
ensures that the jacket cooling water temperature at the outlet from the engine does not fall below a certain level
Fig. 6.04.05: Freshwater generators. Jacket cooling water heat recovery flow diagram
MAN B&W 50 Mark 8/7/6, 46-26 Mark 9/8/7/6 engines
Seawater
In Out
Brine out
jacket cooling water temperature at the outlet from
the engine does not fall below a certain level. Such
a temperature control system may consist, e.g.,
of a special bypass pipe installed in the jacket
cooling water system, see Fig. 6.04.05, or a spe-
cial builtin temperature control in the freshwater
[3] generator, e.g., an automatic start/stop function, or
similar.
If such a special temperature control is not ap-
plied, we recommend limiting the heat utilised to
maximum 50% of the heat actually available at
specified MCR, and only using the freshwater gen-
erator at engine loads above 50%. Considering the
cooler margin of 10% and the minus tolerance of
15%, this heat corresponds to 50 x(1.000.15)x0.9
= 38% of the jacket water cooler capacity Q
used for dimensioning of the jacket water cooler.
Jacket cooling water system
B
A
Deaerating tank
Jacket water
cooler
Cooling
water
MAN Diesel
Expansion tank
Jacket cooling
water circuit
max
min
Tjw
Tjw
K
Jacket water pumps
Main engine
6.04
Page 6 of 12
jw,M
L
M
178 23 700.0
198 71 44-6.2