CIMAC Congress - Schiff & Hafen

CIMAC CONGRESS | BERGEN 2010
modelling framework aims at providing model-based decision
support on: a) energy and emissions optimal design of onboard
machinery, b) performance evaluation under real-service
dynamic conditions for the whole mission envelope of the
system, and c) assessment of the potential and operational
capabilities of innovative designs. The main benefit from this
holistic approach is that the steady-state design characteristics,
off-design operational modes and dynamic/transient behaviour
can be simultaneously assessed and/or optimised in a unified
and consistent modelling framework. The presented approach
can significantly aid the design process for new systems as well
as the energy management, performance prognosis, and control
optimisation and reconfiguration for existing vessels. The main
characteristics and benefits of our methodology are illustrated
via the dynamic modelling of a marine combined cycle system.
Field experiences and opportunities of
modern measurement techniques
T. Philipp, Geislinger GmbH, Austria
Condition monitoring plays an important role in modern
drivelines with combustion engines in order to gain operational
safety, to expand overhaul periods or to detect abnormal
operating conditions. Torsional vibration measurement/
monitoring is a well known and wide spread instrument to
supervise the vibratory behaviour of a certain element (e.g.
torsional vibration damper, torsional elastic coupling) or of the
complete driveline. The Geislinger Monitoring System (GMS)
was originally invented as a monitoring device for dampers and
couplings in combustion engines. Its main goal was – and it
still is today – the monitoring of the damper vibratory twist
angle, mounted on the free end of the engine. The on-line
comparison with reference-data gives direct feedback to the
operator of the installation. It shows the current condition of
the damper or coupling which allows not only a direct
judgement regarding the current situation but also indicates the
necessity of an overhaul. The GMS has proven its appropriateness
in hundreds of installations, mainly on two-stroke marine
applications. NowadAys the GMS is not only used as a
monitoring device for couplings and dampers but as a
monitoring and measurement tool for all kinds of vibratory
aspects in drivelines: The detection of engine misfiring based on
the vibratory behaviour is significantely faster than the widley
used observation of the exhaust temperatures. In future
applications the t.d.c.-signa of electronically controlled engines
can be used to offer not only a faster but also a detailed
information on which cylinder the misfiring takes place.
Theoretically even the detection of engine unbalance is possible
using the same computational approach. A further enhancement
on the capabilities of the GMS is the power-monitoring based
on twist angle measurement. It allows the optimization of fuel
consumption with minimized cost and installation effort
compared to other power-meter solutions. Its effectiveness was
already proven by various installations in wo-stroke and fourstroke
applications. In critical installations the GMS can also be
used as a long-term-measurement device with data storage. This
feature allows the detection of stochastic and irregular load
conditions as a part of failure investigations. A typical example
are reciprocating compressor sets driven by combustion engines.
These applications pass through various and sometimes
unknown load conditions which makes a proper pre-calculation
difficult. Long-term-measurements help to understand the
special behaviour of these installations in order to select best
matching and long lasting products and solutions. This paper
describes the various monitoring and measurement possibilities
of the GMS and possible future applications as a powerful tool
for torsional vibration related problems.
8:30 June 17th Room Scene GH
(3–1) Environment, Fuel & Combustion –
Diesel Engines – Fuels I
A step to reduce SOx emission from ships
– improvement in combustion of higharomatic
and low-sulfur distillate fuel
K. Takasaki, K. Okazaki, D. Yamanishi, Kyushu
University, Japan,
K. Sugiura, Mitsui Engineering and Shipbuilding
Co., Ltd., Japan,
S. Baba, H. Tanaka, Hitachi Zosen Corporation,
Japan
New regulations of the International Maritime Organization
(IMO), introducing drastic reductions in fuel sulfur content, allow
0.1% sulfur in fuels used in emission control areas (ECA), starting
from 2015. Together with the worldwide situation of decreasing
fuel resources the introduction of alternative fuels complying
with future regulations displays an important research these days.
Light Cycle Oil (LCO) also referred to as “Cracked gas oil”, a subproduct
from the FCC process in refining, has the potential to be
used as an alternative for current marine fuels. Due to the
desulfurization in the FCC process, LCO reaches a low sulfur
content of 0 to 0.2%. However, LCO shows a high content of
aromatic hydrocarbons, mainly composed of one and/or two ring
aromatics. As the number of fused benzene rings is rather low,
LCO has a low and comparable viscosity to gas oil. The high
aromaticity of LCO, 70-80%, results in a strong deterioration of
the ignition and combustion properties of the fuel. Therefore
experimental investigation showing the influence of LCO on the
overall combustion characteristics is necessary in order to
elaborate the feasibility of LCO as a low sulfur fuel. Experiments
have been carried out in the following order:
1. Properties including the aromaticity of several LCO samples
from Japanese oil refineries have been investigated. Their ignition
quality has also been examined using the well known constant
volume analyzer FCA (Fuel Combustion Analyzer). The results
confirmed that recent LCO samples dating from the last four years
show significantly poorer ignition quality compared to samples
taken more than ten years ago.
2. Selecting a LCO sample of average fuel quality, combustion
characteristics have been investigated in detail, using a specially
designed visual test engine (bore/stroke: 190/350 mm, engine
speed: 400 rpm). Investigation of the flame images clearly
confirmed that the application of LCO leads to longer ignition
delay, longer after-burning and longer spray/flame burnup length
compared to MDO (Marine Diesel Oil) combustion.
3. Selecting another LCO sample of relatively good quality,
running tests, using a full-size single-cylinder low-speed test
engine (bore/stroke: 400/1350 mm, engine speed: 178 rpm),
have been carried out. The application of LCO in low speed
engines could not clearly indicate a difference in ignition quality
compared to the use of MDO. However the deterioration in
combustion quality due to LCO application could be detected by
analyzing the exhaust gas data.
4. Unlike the case of low speed engines, LCO could have severe
influence on medium or high-speed engines, considering not
only the engine speed but also the combustion chamber size. The
same LCO sample as in 3. has been tested using a high-speed
turbo-charged 4-stroke marine engine (bore/stroke: 110/125 mm,
84 Ship & Offshore | 2010 | No. 3