Man B&W L35MC6-TII, Project Manual

Page: 68 / 375

MAN B&W 3.02
Page 1 of 2
MAN Diesel
198 45 934.5 MAN B&W S80MC, S80MC-C/ME-C, K80MC-C/ME-C, S70MC,
S70MC-C/ME-C/ME-GI, L70MC-C/ME-C, S65ME-C/ME-GI,
S60MC, S60MC-C/ME-C/ME-GI/ME-B, L60MC-C/ME-C,
S50MC, S50MC-C/ME-C/ME-B, S46MC-C/ME-B, S42MC,
S40MC-C/ME-B, S35MC, S35MC-C/ME-B, L35MC, S26MC6
Exhaust gas receiver with variable bypass
Option: 4 60 118
Compensation for low ambient temperature can
be obtained by using exhaust gas bypass sys-
tem.
This arrangement ensures that only part of the
exhaust gas goes via the turbine of the turbo-
charger, thus supplying less energy to the com-
pressor which, in turn, reduces the air supply to
the engine.
Please note that if an exhaust gas bypass is ap-
plied the turbocharger size and specification has
to be determined by other means than stated in
this Chapter.
Emergency Running Condition
Exhaust gas receiver with total bypass flange
and blank counterflange
Option: 4 60 119
Bypass of the total amount of exhaust gas round
the turbocharger is only used for emergency run-
ning in the event of turbocharger failure on en-
gines, see Fig. 3.02.01.
This enables the engine to run at a higher load
with only one turbocharger under emergency
conditions. The engine’s exhaust gas receiver will
in this case be fitted with a bypass flange of ap-
proximately the same diameter as the inlet pipe
to the turbocharger. The emergency pipe is yard’s
delivery.
Extreme Ambient Conditions
As mentioned in Chapter 1, the engine power
figures are valid for tropical conditions at sea
level: 45 °C air at 1000 mbar and 32 °C sea water,
whereas the reference fuel consumption is given
at ISO conditions: 25 °C air at 1000 mbar and
25 °C charge air coolant temperature.
Marine diesel engines are, however, exposed to
greatly varying climatic temperatures winter and
summer in arctic as well as tropical areas. These
variations cause changes of the scavenge air
pressure, the maximum combustion pressure, the
exhaust gas amount and temperatures as well as
the specific fuel oil consumption.
For further information about the possible coun-
termeasures, please refer to our publication titled:
Influence of Ambient Temperature Conditions
The publication is available at: www.mandiesel.com
under ‘Quicklinks’
→
‘Technical Papers’
Arctic running condition
For air inlet temperatures below 10 °C the pre-
cautions to be taken depend very much on the
operating profile of the vessel. The following al-
ternative is one of the possible countermeasures.
The selection of countermeasures, however, must
be evaluated in each individual case.
Exhaust Gas Bypass