CIMAC Congress - Schiff & Hafen

CIMAC CONGRESS | BERGEN 2010
10:30 June 16th Room Peer Gynt Salen
(11–2) Users’ Aspects –
Marine Applications – Monitoring
Shipboard engine performance assessment
by comparing actual measured data to
nominal values produced by detailed
engine simulations
N. Kyrtatos, E. Tzanos, NTUA, Greece,
J. Coustas, D. Vastarouhas, E. Rizos, Danaos
Shipping Co. Ltd., Greece
During the lifetime of a ship’s engine, the original shop trials and
sea trials are often the only available reference conditions, which
can be used for engine performance analysis, during ship operation.
In the case of container vessels, the engine actual operating point
may be far away from any reference conditions. In addition,
charterers may request different operating regimes for the ship. In
such cases, the shipping company needs to predict, with confidence,
details about the operation and performance of the engine and its
auxiliaries, in conditions where there is no measured or reference
data. Extrapolation, using corrected figures from shop/sea trials,
often results in errors. This paper presents a novel method and
procedure for obtaining performance figures for a specific shipboard
engine, at any possible operating point, at different operating
regimes. These reference figures are produced by using detailed
simulation models for engine performance prediction. Up to now,
such detailed models are mainly used by manufacturers for engine
design. The nominal performance figures produced by detailed
simulation models can also be used as reference, to compare with
any shipboard measured actual performance data, for engine
performance evaluation. The paper describes the above procedure
used by Danaos Shipping Co. on two different main engines of large
containerships, typical of its fleet. The implementation initially
involved collection of geometric and operational data for each
engine. Then the generic engine simulation software Mother (Motor
Thermodynamics) was tuned and pegged using the shop test data
and initially validated using the sea trials data for each specific
engine. The results of simulation allowed prediction of all engine
parameters within 3% of actual measured values at sea trials. A task
force within the Danaos Technical Department was specially trained
in using the simulation software. Further sets of simulations at
operating conditions away from sea/shop trials, allowed the
prediction of all engine parameters and comparison to measured
data and thus provided a good baseline for engine performance
evaluation and condition assessment.
One way to condition-based survey for
marine diesel engines
J. Rebel, Germanischer Lloyd, Germany
Particularly in times of economic crisis, availability and hence
reliability is very important for cargo vessels. This is the main reason
why an increasing number of shipping companies invest in
condition monitoring technology and move towards conditionbased
maintenance. Classification societies are involved in this subject in
order to support non-open-up surveys by offering respective survey
arrangements. Since 2005, Germanischer Lloyd has been engaged in
pilot projects for condition monitoring (CM) systems covering the
crank-train of two-stroke crosshead diesel engines and other items
of diesel equipment. The main engine of the test vessels C/V “Norasia
Alya” and C/V “Hamburg Express” are equipped with bearing wear
condition monitoring. In joint industry projects, the shipping
company, the engine licenser, the manufacturers of the CM systems
and the GL as the responsible classification society have been
working closely together in order to gain field experience with these
tools and to develop an efficient way to condition-based survey
procedures. The paper continues the presentation of selected results
of the ongoing field tests regarding the verification of the condition
monitoring method and the definition of requirements for the
condition-based maintenance procedures. In case of the crank-train
bearing monitoring, the condition-based survey procedure is fully
developed and will be presented for both vessels.
Development of a remote non intrusive
diagnosis system for two stroke diesel
engines
F. J. Jimenez-Espadafor, J. A. Becerra Villanueva,
M. Torres Garcia, T. Sanchez Lencero, Seville
University, Spain,
F. Fernandez-Vacas, M. Bueno del Amo, Endesa
Generacion, Spain
Maintenance cost and unexpected failures can be drastically reduced
in low speed diesel engines using vibro-acoustic analysis. This
methodology has presented as a reliable method for detection of
manufacturing faults, running damages and other abnormalities in
engine and its components. Continuous trending keeping deviations
of monitorized parameter allows also reduction of fuel consumption,
optimize exhaust emissions, and increase components life time and
increase safety. This paper describes the method of vibration
monitoring for fault diagnosis based on time-windowing and
frequency analysis. The effectiveness is demonstrated based on the
results of two year operation on a large two stroke power plant diesel
engine, located in Mahon, Spain.
Evaluation method of engine and
propulsion shaft alignment for large vessel
I. Sugimoto, T. Nakao, Hitachi Zosen Diesel and
Engineering Co., Ltd., Japan
Propulsion shaft alignment of large vessel is sensitive to draft change
from light draft to full load draft. Each initial bearing offset of the
shaft alignment changes by the fluctuation of draft level. Especially,
it presents vessels such as VLCC and large bulk carrier. The reasons
include a propulsion shaft diameter stiffer and an engine main
bearing center distance shorter. Those correspond to engine
development trend of higher power and more compact size. The
initial bearing offset change affects each bearing performance. In
some cases, the change causes sever trouble to an engine and
propulsion shaft. It is necessary to estimate an engine crankshaft
and propulsion shaft alignment against a draft change for both
engine development trend and improving reliability of bearings and
shafts. Our past study was mainly focused on engine bearings in
service condition. Before in service, it is indispensable for users to
estimate reliability both of engine and propulsion shaft alignment
against a vessel deformation and engine thermal expansion. So, an
evaluation method of both engine and propulsion shaft alignment
has developed for large vessel such as VLCC and bulk carrier. Input
parameters are a vessel deformation information and an engine
thermal expansion data. The vessel deformation is able to be given
by a vessel deformation result by a FEM analysis, a directly
measurement result of shaft alignment of a similar vessel or an
inverse calculation result of shaft alignment of a similar vessel by
using our developed software. In this tudy, an inverse calculation
result is used. The evaluation values are conventional shaft alignment
calculation values and engine crankshaft values. The conventional
shaft alignment values include bearing load, propulsion shaft angle
70 Ship & Offshore | 2010 | No. 3