MAN B&W L28/32H, Manual

Page: 31 / 218

General
99.34
The composition of the exhaust gases emitted by our
medium-speed four-stroke diesel engines during full
load operation and depending on the air/fuel ratio is
as follows:
% Volume
Nitrogen N
2
approx. 76
Oxygen O
2
approx. 13
Carbon dioxide CO
2
approx. 4
Water (vapour) H
2
O approx. 6
Argon Ar approx. 1
Ash, soot, NO
x
, CO, HC, etc. rest
However, as regards the environmental impact
attributable to diesel exhaust gases only the
components listed under "Rest" are of interest, and
of these, above the various proportion of carbon
monoxide, CO, of nitrogen oxides, NO
x
, sulphur
dioxide SO
2
and of the hydrocarbons, HC, that are
known as noxious materials on account of their
toxicity.
D 10 28 0 Exhaust Gas Emission
1624461-6.2
Page 1 (1)
The ash and SO
2
content of the exhaust gas is solely
determined by the composition of the fuel and not by
the combustion in the engine.
SO
2
can be determined by the empirical relation-
ship: SO
2
* = (21.9 x S) - 2.1 (kg/tonne fuel). Where
S is sulphur content of fuel in % of weight.
The soot emission, though it does play a role, poses
no problem in case of super-charged engines on
account of the large amount of excess air compared
with naturally aspirated engines.
As the NO
x
emission is also greatly influenced by the
site and operating conditions of the engine (e.g.
charge air temperature), the MAN B&W Diesel A/S,
Holeby works should be consulted and advised of
any existing local ordinances before any statements
regarding emissions are made in case of concrete
projects.
* Reference: Lloyds Register Marine Exhaust
Emissions Research.
g/Nm (5% O ),
g/kWh
200
300
400
500
600
700
800
900
1000
ppm
25 50 75 100 Load %
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
3
2
g/kWh
ppm (15% O , wet)
g/Nm (5% O , dry)
ppm (13% O , dry)
3
2
2
2
Fig. 1. No
x
emission L23/30H and L/V28/32H engines according to ISO 3046 conditions.