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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 and ME-C/-GI engines are, as
standard, delivered in compliance with the IMO
speed dependent NOx limit, measured according
to ISO 8178 Test Cycles E2/E3 for Heavy Duty
Diesel Engines. These are referred to in the Extent
of Delivery as EoD: 4 06 060 Economy mode with
the options: 4 06 060a Engine test cycle E3 or 4
06 060b Engine test cycle E2.
NO x reduction methods
The NO x content in the exhaust gas can be reduced
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 x reduction
The ME engines can be delivered with several
operation modes, options: 4 06 063 Port load, 4
06 064 Special em<strong>is</strong>sion, 4 06 065 Other em<strong>is</strong>sion
limit, and 4 06 066 Dual fuel.
These operation modes may include a ‘Low NOx
mode’ for operation in, for instance, areas with restriction
in NOx em<strong>is</strong>sion.
For further information on engine operation
modes, see Extent of Delivery.
30�50% NO x reduction
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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 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 95�98% NO x reduction
<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 1990 on five vessels, using
Haldor Topsøe catalysts and ammonia as the reducing
agent, urea can also be used.
The 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 em<strong>is</strong>sion control,
please refer to our publication:
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 ME/ME�C/ME-B/GI-TII engines 198 75 40-0.1
MAN Diesel