detailed programme - SIMS - Scandinavian Simulation Society

Abstract: The transient temperature conditions near the bottom of well IDDP-1
in Krafla, which was drilled into a magma intrusion, have been simulated by some
simple models addressing: (i) evolution of temperature conditions at the magma
intrusion, (ii) cooling of a permeable layer above the magma due to drilling
circulation losses, (iii) reheating of the permeable layer after drilling and (iv)
temperature evolution during discharge testing in 2010. The modelling is quite
speculative because of limited data constraints, but results indicate that the
temperature conditions and evolution can be explained by the models used. The
possibility that the magma was emplaced during the Krafla volcanic episode 25 –
35 years ago can neither be confirmed nor refuted, but if the intrusion is so old a
thickness of at least 50 – 100 m is required. The effective thick¬ness of the
permeable layer and its equilibrium temperature, are estimated to be about 45 m
and 390 – 400°C, respectively. No direct contact with the magma is needed to
explain the superheated (up to 380°C) steam discharged by well IDDP-1. The
situation near the bottom of the well clearly warrants further study, both through
more complex modelling and with further data-constraints.
Authors: Guðni Axelsson, Thorsteinn Egilson, Sigríður S. Gylfadóttir.
Paper 24
Title: Condition monitoring of an epicyclic gearbox at a water power station
Keyword: condition monitoring, diagnostics, higher order derivatives, epicyclic
gearbox
Abstract: Epicyclic gearing or planetary gearing is a gear system, which consists
of one or more outer gears, or planet gears, revolving about a central, or sun
gear. Typically, the planet gears are mounted on a movable arm or carrier which
itself may rotate relative to the sun gear. Epicyclic gearboxes are challenging to
monitor due to complex structure with many rolling elements. Complex structure
and versatile components also mean a long stoppage if a failure occurs.
Therefore, an early detection of incipient faults is important.
In this paper, vibration analysis is used for condition monitoring of an epicyclic
gearbox at a water power station. There is a distinct difference between vibration
quantities: vibration velocity responds very well to the vibrations with frequencies
less than 1000 Hz; an even better response is gained by acceleration and its
higher derivatives, which also include more information on higher frequencies.
Because of a quite high rotational speed of the output, the vibration velocity is
not good enough for condition monitoring of the gear in question. Acceleration
and its higher order derivatives should be used to get better responsiveness for
changes in the condition of the gearbox.
Modelling is needed to calculate the vibration components in the frequency range
to identify the possible faulty components. There was also one vibration
component in the gear, which source was not definitely discovered.
Authors: Jussi Immonen, Sulo Lahdelma, Esko Juuso.
Paper 18
Title: Input Variable Selection in Modelling of Desulphurization Efficiency
Keyword: desulphurization plant, input variable selection, modelling
Abstract: Several methods are applied in order to find the input variables with
predictive power to the modelling of SO2 removal efficiency in a desulphurization
plant. In model development, the preliminary assumption is that one or several
candidate variables are capable of describing some of the output behaviour. In
non-linear and complex industrial processes, the nature of the relationships
between the variables may be vague and a functional first principles based model
may be impossible to define. Therefore, it is justified to use data-driven statistical
modelling approaches such as artificial neural networks (ANNs). However, such
models may become corrupted due to the inclusion of uninformative, weakly
informative or redundant variables. In this study, the emphasis is on the selection