MAN B&W 1.01
Page 2 of 2
MAN Diesel
198 91 58-9.0
MAN B&W ME-GI/ME-C-GI TII engines .2 and higher
Tier II fuel optimisation
NO
x
regulations place a limit on the SFOC on
two-stroke engines. In general, NO
x
emissions will
increase if SFOC is decreased and vice versa. In
the standard configuration, MAN B&W engines are
optimised close to the IMO NO
x
limit and, there-
fore, NO
x
emissions may not be further increased.
The IMO NO
x
limit is given as a weighted average
of the NO
x
emission at 25, 50, 75 and 100% load.
This relationship can be utilised to tilt the SFOC
profile over the load range. This means that SFOC
can be reduced at part load or low load at the
expense of a higher SFOC in the high-load range
without exceeding the IMO NO
x
limit.
Improved fuel consumption on gas fuel
In the ME-GI concept, NO
x
is reduced substan-
tially on gas fuel compared to diesel/HFO opera-
tion. As much as possible of this NO
x
margin is
exchanged for improved SFOC, while not exceed-
ing the E3 NO
x
cycle value for the diesel reference
case.
The SFOC optimisation is carried out in the part-
load range from 75% load and below. Further to
this SFOC improvement on gas, no other part- or
low-load optimisation methods are applicable for
the ME-GI engine.
In this project guide, data is based on high-load
optimisation unless explicitly noted. For derated
engines, calculations can be made in the CEAS
application described in Section 20.02.
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