Service Experience - MAN Diesel & Turbo - 首页

test installation of a water mist catcher.
We have made a full scale test on various
water mist catcher designs, including
some sub-supplied designs, which
MAN Diesel & Turbo design Sub-supplier I Sub-supplier II
Fig. 33: Tested designs
Efficiency [%]
100 100
90 90
80 80
70 70
60 60
50 50
40 40
30 30
20 20
10 10
94,8 94.8 94,7 94.7
88,7 88.7
69.7 69,7
16 Service Experience of MAN B&W Low Speed Diesel Engines
have been applied in big numbers in our
large bore engines. Fig. 33 shows three
of the tested designs and Fig. 34 shows
an example of the results obtained. In
WMC efficiency as function a function of of air air velocity velocity
Constant boundary boundary conditions: conditions
Mass flow of water = 0.0016 kg/s
Massflow Air temperature of water = 25 ≈ 0.016 kg/s
Air temperature ≈ 25 C
Air absolute pressure ≈ 3.5 bara
oC Air absolute pressure = 3.5 bara
88.2
88,2
66.8
66,8
92.6 92,6
84.1 84,1
63.3
63,3
MAN Diesel & design Turbo
Sub-supplier Design II
Sub-supplier II I
0 0
5.5 6 6.5 7 7.5 8
5,5 6 6,5 7 7,5 Velocity [m/s] 8
Velocity[m/s]
Fig. 34: Full scale test results
this case, the water mist catching efficiency
is shown as a function of air
velocity and very big deviations in efficiency
can be seen.
On the basis of these results and an up-
date of the mechanical design, we have
now fully re-specified the water mist
catcher design, and we expect that this
will limit water ingress related scuffing.
Cracks in the bedplate lifting bracket of K98
engines
In 2008, cracks in the lifting bracket
on K98 bedplates were discovered on
engines produced 5-7 years earlier,
see Fig. 35. Soon after the first cracks
were discovered, a so-called ‘Circular
Letter’ was issued to all owners/operators
of K98 engines, see Fig. 36. In
this letter we asked for help to inspect
for lifting bracket cracks. Furthermore,
we informed about preventive countermeasures,
which were burr grinding
of the weld seams on the aftmost and
foremost brackets. Also, a repair procedure
was developed when the cracks
first occurred. A modified bracket profile
has been designed for new engines,
see Fig. 37.
Due to the high number of K98 engines
in service, these rectifications are still
ongoing and, fortunately, we are able to
perform this work without disturbing the
operation of the vessels involved.