CIMAC Congress - Schiff & Hafen

CIMAC CONGRESS | BERGEN 2010
Investigating the ignition properties
of marine fuels by the Fuel Ignition Analyser
and its comparison to marine engines
P. de Hoog, K. Steernberg, Shell, The Netherlands, S.
Forget, Shell, UK
The manufacturing of marine fuels is facing increasing challenges as
the result of tightening environmental legislation relating to
emissions from shipping. This will affect fuel quality, mostly by the
increasing demand for low sulphur fuels. At the same time the
increasing demand for middle distillates for transport application,
leads refineries to increased conversion, which normally impacts the
volume and quality of heavy fuel oil. Properties particularly affected
are stability and the ignition and combustion qualities. Poor ignition
and combustion may result in unreliable engine operation. For that
reason, consideration is being given to the inclusion of some form of
ignition/combustion control in the international marine fuels
standard, ISO 8217, namely the Shell developed Calculated Carbon
Aromaticity Index (CCAI) value, which has been widely applied
already as indicator of ignition quality. Another IP method to
measure ignition quality, namely the Estimated Cetane Number
(ECN) measured by Fuel Ignition Analyzer (FIA) is currently being
considered for next versions. When new techniques are accepted for
specification purposes it is important that these tests measure
fundamental properties and have been subjected to a robust review
process, so that a sound scientific basis is available that demonstrates
the relationship to fuel performance and mitigates the risk of product
quality incidents. First results of the evaluation of the FIA ECN by
Shell Global Solutions have been presented at the CIMAC 2007
congress.[1] As results were not conclusive, research in this area was
continued with the purpose of further improving our knowledge of
fuel oil ignition quality and better understanding the possibilities
and limitations of FIA ECN. This additional work will be reviewed in
this paper. The profound understanding of the influence of fuel
composition on the ignition quality has been one of the main
elements of the programme. Fit for purpose fuel is a key ingredient
to have a trouble-free operation on a vessel. For that reason, the FIA
ECN of a variety of refinery residual components was compared and
related to the effect on the ignition quality of the final fuel oil. It was
found that not all blending components can be measured directly
with the FIA due to viscosity constraints of the method and that
some blending components may show nonlinear blending relations.
Therefore, it is not straightforward to blend to a certain ECN
specification and it will increase complexity and costs. The second
element is the influence of FIA test parameters on the FIA ECN. The
FIA ECN is measured at a standard temperature and pressure, which
is required for comparison of fuel samples. However, engines run
normally at different temperatures and pressures, therefore several
fuel oil samples have been measured at the standard FIA conditions
and with varying FIA test parameters in order to identify the influence
of those parameters on the ECN. The relative ranking of the fuel oil
samples is also reviewed. It was shown that the temperature can
change the magnitude of the ECN differences between the fuels. This
indicates that a single FIA ECN limit might not be a good indication
of ignition quality for different engines that operate at changing
conditions. Ultimately, the ECN should provide a result that could
be used to predict reliable ignition and combustion performance in
diesel engines with a high degree of confidence. Therefore, the ECN
of several fuel oils are related to the ignition data from 2- and 4-stroke
engines, namely the AVL Caterpillar 1Y540 and the Bolnes 3(1) DNL
170/600 research engines at Shell and the Wärtsilä 4RT-flex58TB
research engine. The ranking of the ignition quality of the fuel oil
samples in the three engines and the ECN will be compared in the
paper. The experience that has been gained so far indicates that a
single ECN limit cannot be used for specification purposes. The
range of engines and operating conditions is too large to describe the
ignition performance with a single limit. It might be that one ECN
limit will be ideal for one group of engines, but may be too low for
another group of engines resulting in operating problems.
8:30 June 17th Room Troldtog
(2–6) Fundamental Engineering –
Piston Engines – Mechanics II
Stability of controlling operation inputs
over inlet air conditions of turbocharged
compression-ignition engines
G. Chen, Gannon University, USA
This paper investigates the operation stability and ultimate responses
of turbo-charged compression-ignition engines as engine operation
inputs are controlled over engine ambient and/or inlet air conditions.
The in-cylinder combustion and output performances of an engine
of this type are generally affected by its ambient, inlet and cylinder
intake air conditions. The effects are extendedly analyzed and
summarized. In consideration that an operation input, such as fuel
injection/combustion-start timing, can be adjusted to alter the
engine in-cylinder combustion and outputs over the ambient or inlet
air condition that may usually vary, the stability of engine operation
and conditions for maintaining a stable operation, as an operation
input is under adjustment, are studied and analytically predicted.
The study addresses various cases in which different options for
taking an engine inlet and/or intake manifold air condition to
execute the control are considered. Then, the consequent effects of
adjusting the operation input and engine ultimate responses over
the inlet/intake conditions are investigated. The criteria for achieving
a stable operation and the ultimate state of operation of the engine
with the optional cases are also identified.
Full cyclic simulation and fatigue design of
conrod and crankshaft for medium-speed
diesel engine
J. H. Lee, S. C. An, K. H. Jung, J. H. Son, J. G. Bae,
Hyundai Heavy Industries Co., Ltd., Korea
Durability design of the crankshaft for marine diesel engines is not
easy because a dynamic load acting on the crankshaft is combination
of bending moment and torque and its magnitude and direction
continuously vary in every time. It is necessary to understand a nonproportional
loading of bending moment and torque as well as
multi-axial fatigue theory. In a practical point of view, IACS M53
guideline is popularly used and if necessary, additionally simple FE
method is applied in order to evaluation the fatigue strength more
conservatively. However, a basic assumption to combine bending
stress and shear stress in IACS M53 is different from a real stress
history of crankshaft. The variation of inertia and pressure force in
fatigue analysis of the conrod is generally taken into consideration.
Since a weak point of the conrod and effective loading on fatigue
damage is different relatively, the fatigue strength of the conrod
should be evaluated based on not the load variation but the stress
history. The local and global oil film pressure distribution is very
important for optimum design of conrod and is resulted from the
elasto-hydrodynamic bearing analysis. In this study, the durability
design and verification of the crankshaft and conrod was carried out
based on the full cycle simulation during one cycle that is an analysis
technique to consider the time-varying forces and moments in one
cycle. In case of the crankshaft, the radial force and tangential force
on the crank pin were calculated and also an alternating torque
86 Ship & Offshore | 2010 | No. 3