MAN B&W 2.12
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MAN Diesel
MAN B&W MC/MC-C/ME/ME-B/MEC/MEGI engines 198 38 446.5
Emission Control
IMO NO
x
Emission Limits
All ME, ME-B, ME-C and ME-GI engines are, as
standard, delivered in compliance with the IMO
speed dependent NO
x
limit, measured accord-
ing to ISO 878 Test Cycles E2/E3 for Heavy Duty
Diesel Engines.
NO
x
Reduction Methods
The NO
x
content in the exhaust gas can be re-
duced with primary and/or secondary reduction
methods.
The primary methods affect the combustion pro-
cess directly by reducing the maximum combus-
tion temperature, whereas the secondary me-
thods are means of reducing the emission level
without changing the engine performance, using
external equipment.
030% NO
x
Reduction
The ME engines can be delivered with several opera-
tion modes: 4 06 062, 4 06 063, 4 06 064,
4 06 065, 4 06 066.
These operation modes may include a ‘Low NO
x
mode’ for operation in, for instance, areas with
restriction in NO
x
emission.
For further information on engine operation
modes, see Extend of Delivery.
3050% NO
x
Reduction
Water emulsication of the heavy fuel oil is a well
proven primary method. The type of homogeni-
zer is either ultrasonic or mechanical, using water
from the freshwater generator and the water mist
catcher. The pressure of the homogenised fuel
has to be increased to prevent the formation of
the steam and cavitation. It may be necessary to
modify some of the engine components such as
the fuel oil pressure booster, fuel injection valves
and the engine control system.
Up to 9598% NO
x
Reduction
This reduction can be achieved by means of
secondary methods, such as the SCR (Selec-
tive Catalytic Reduction), which involves an
aftertreatment of the exhaust gas, see Section
3.02.
Plants designed according to this method have
been in service since 990 on four vessels, using
Haldor Topsøe catalysts and ammonia as the re-
ducing agent, urea can also be used.
The compact SCR unit can be located separately
in the engine room or horizontally on top of the
engine. The compact SCR reactor is mounted
before the turbocharger(s) in order to have the
optimum working temperature for the catalyst.
However attention have to be given to the type of
HFO to be used.
For further information about the pollutants of the
exhaust gas see our publications:
Exhaust Gas Emission Control Today and Tomorrow
The publication is available at www.mandiesel.com
under ‘Quicklinks’ → ‘Technical Papers’
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