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About the project
There is a rapidly increasing use of computer simulations in
industry to optimize products, to reduce product development
costs and time by design optimization, and to train operator.
In fact, computational modelling and software made great achievements
in the latest years and this had
a radical impact on academic disciplines such as Solid and Structural
Mechanics, Fluid Dynamics, and Electromagnetics, as well as on industrial simulation,
design and quality assestment.
Whereas in the past it was considered sufficient to simulate
subsystems separately, the current trend is to simulate
increasingly complex physical systems composed of subsystems from
multiple domains.
A library of reusable model components for process applications will be developed
in the new modeling language Modelica. A Modelica tool
will be extended with features for operator training simulation. The aim of the proposed
research is also to integrate existing models of the paper board manufactoring process
at AssiDomäan Carton Board AB, together with on line identification routines, into
a comprehensive Modelica model, with the purpose of interactive operator simulation
and operator simulation and operator assisted optimization of important quality variables.
Background
AssiDomän Frövi produces 350.000 tons of board per year
on one 7 m wide and 250 m long board machine. The board is
composed of four plies formed in separated headboxes. Most of the
used pulp is bleached and unbleached sulphate pulp produced
within the plant. The bleached pulp is used on the topside for a
bright and white surface. quality requirements are very severe, close to the
operating limits set by the process equipment and the allowe quality variations are small.
The process and associated control systems are very complex. It's a complicated
nonlinear and time-varying multi-input multi-output process. The model of the process
contains a large amount of uncertainty and is affected by unknown and unmeasured
distrubances. A more detailed description of the mill is
here.
In such a complex system, simulation tools can be extremely useful.
There have been different efforts to develop a simulation tool for the
paper board in Frövi. In his licentiate thesis, Jens Petterson, developed
a bending stiffness predictor for the carton board. Starting from previous works
(Gutman & al.) he carried out a sophisticate
grey box modeling of the process with very good results.
A different approach is nowadays carryed on in a collaboration between
AssiDomän Frövi, Solvina,
Dynasim and the division
of System Theory and Optimization
at the Royal Institute of Technology in Stockholm
and financed by Nutek.
The aim of this project is to build a model of the entire paper process with
Dymola, a simulation tool for modeling of large systems, based on
Modelica language. Modelica is an
object-oriented, general-purpose modeling language that is under
development in an international effort to introduce an expressive
standardized modeling language.
Besides, another project is going on, inside the precedent context. A
grey box modeling of another board property (i.e. dimensional stability)
is being developed by Gianantonio Bortolin, using Petterson's approach.
Next, a more detailed description of the previous projects follows:
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