Een lineair programmeringsmodel voor de inzet van reststoffen bij Hoogovens.
Report 93.3.LT.4125, Transport Engineering and Logistics.
At Hoogovens IJmuiden remainder materials are being released when steel is
produced.Those materials that contain iron are recycled in the proces of
iromnaking. At Hoogovens these materials are called 'industrial materials'.
This circular course flows via a storage terrain where all the industrial
materials are stored separately. From this storage the materials are
transported by truck to another dump where they are mixed. The planning
that is used for the transportation of the industrial materials is the
subject of this project.
In the preliminary investigation of this study an overview of the flows
of industrial materials is made. This investigation makes clear that the
planning of industrial materials exerts an influence to different
aspects. The proportion of the various industrial materials exerts its
influence to the composition of the mixture. Chemical limits are set
to the mixture; those limits should not be exceeded. With the planning it is
possible to control the stocks of the industrial materials. Minimal stock is
strived after. On the other hand, the continuity of the mixture needs a
continuous planning. The continuity of the mixture is important because of
the resets of the sinter producing proces.
To support the making of the planning, a lineair programming model is
developed. With a horizon of half a year this model calculates a planning
that strives after minimwn stock value. Chemical limits and the minimum
stocks are the restrictions where the planning must stick to. Continuity
criterions are modelled, so a modification in the planning is adviced only
if the profit is higher than the reset costs of this modification. The
main function of the model consists of four subfunctions: capital management,
chemical management, stock management and continuity management.
An application of the LP-model of the industrial materials planning is written
in the lineair progranuning system XA, with a shell of PreXA. For modification
of the input and analysis of the output the spreadsheet program Excel is used.
Worksheats are defined to present the information in grafics and tables.
With a configuration of the LP-model of the planning of industrial materials
some experiments are done to demonstrate the possibilities of the model. This
configuration is a model of the actual system of industrial materials at
Hoogovens and can be used to support the planning.
While not all criterions of the industrial materials are known quantitativily,
the application does not use all possibilities of the model. When the
criterions of the chemical composition of the mixture are quantified, these
extra possibilities can be used effectivly. Also with a limited configuration,
which is easier accessible for the user, the model can support the making of a
planning for the industrial materials.
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