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MAN B&W 2.12
Em<strong>is</strong>sion Control
IMO NO x Em<strong>is</strong>sion 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 according
to ISO 8 78 Test Cycles E2/E3 for Heavy Duty
Diesel Engines.
NO Reduction Methods
x
The NO content in the exhaust gas can be re-
x
duced with primary and/or secondary reduction
methods.
The primary methods affect the combustion process
directly by reducing the maximum combustion
temperature, whereas the secondary methods
are means of reducing the em<strong>is</strong>sion level
without changing the engine performance, using
external equipment.
0�30% NO Reduction
x
The ME engines can be delivered with several operation
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 em<strong>is</strong>sion.
For further information on engine operation
modes, see Extend of Delivery.
30�50% NO Reduction
x
Water emulsification of the heavy fuel oil <strong>is</strong> a well
proven primary method. The type of homogenizer
<strong>is</strong> either ultrasonic or mechanical, using water
from the freshwater generator and the water m<strong>is</strong>t
catcher. The pressure of the homogen<strong>is</strong>ed 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.
Page of
Up to 95�98% NO Reduction
x
<strong>Th<strong>is</strong></strong> reduction can be achieved by means of
secondary methods, such as the SCR (Selective
Catalytic Reduction), which involves an
after�treatment of the exhaust gas, see Section
3.02.
Plants designed according to th<strong>is</strong> method have
been in service since 990 on four vessels, using
Haldor Topsøe catalysts and ammonia as the reducing
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 <strong>is</strong> 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 Em<strong>is</strong>sion Control Today and Tomorrow
The publication <strong>is</strong> <strong>available</strong> at www.mandiesel.com
under ‘Quicklinks’ → ‘Technical Papers’
MAN B&W MC/MC-C/ME/ME-B/ME�C/ME�GI engines 198 38 44�6.5
MAN Diesel