Sie wollen auch ein ePaper? Erhöhen Sie die Reichweite Ihrer Titel.
YUMPU macht aus Druck-PDFs automatisch weboptimierte ePaper, die Google liebt.
TECHNOLOGY<br />
Mo<strong>de</strong>rnisation of melting and casting furnaces<br />
C. Hamers, Oberhausen<br />
In or<strong>de</strong>r to survive in today’s<br />
competitive environment the producers<br />
of aluminium castings continuously<br />
have to face increasingly<br />
stringent <strong>de</strong>mands on quality, the<br />
need for ever greater production<br />
quantities and the need for a reduction<br />
in energy consumption.<br />
They can tackle these challenges<br />
in two ways: either by using new<br />
state-of-the-art melting and casting<br />
equipment or by carrying out<br />
a programme of mo<strong>de</strong>rnisation on<br />
existing plants. This paper focuses<br />
on the latter.<br />
When consi<strong>de</strong>ring the mo<strong>de</strong>rnisation<br />
of existing facilities for the large-scale<br />
production of high quality castings<br />
one should first consi<strong>de</strong>r the melting<br />
and casting furnace because it is in<br />
the furnace that the casting process<br />
begins. The operators of existing melt-<br />
ing and casting plants are often confronted<br />
with problems such as:<br />
• <strong>de</strong>terioration of the equipment<br />
• high energy consumption<br />
• inhomogeneous metal temperatures<br />
• inhomogeneities in metal alloys<br />
• difficulties with start-up metal<br />
flow control<br />
• turbulence in the metal flow<br />
• difficulties in maintaining a con-<br />
stant metal level in the laun<strong>de</strong>r<br />
• poor control of casting table<br />
speeds<br />
• limited access to the furnace<br />
chamber<br />
• high levels of dross formation<br />
• ina<strong>de</strong>quate production output.<br />
The first and easiest step towards improving<br />
casting results and being able<br />
to <strong>de</strong>liver high quality products is to<br />
have a mo<strong>de</strong>rn furnace <strong>de</strong>sign. It is<br />
important to equip furnaces with the<br />
following features if one wishes to im-<br />
a b<br />
c d<br />
prove not only quality and output but<br />
also to save energy:<br />
• a furnace door that gives com-<br />
plete and easy access to the whole<br />
interior of the furnace chamber<br />
and which can be closed and<br />
properly sealed<br />
• a furnace pressure control and<br />
regulation <strong>de</strong>vice in the flue gas,<br />
combined with sealed furnace<br />
inlets and outlets<br />
• a very efficient burner system<br />
tailored to the specific furnace<br />
• burners with optimised flame<br />
direction and location for im-<br />
proved heat transfer; a regenera-<br />
tive burner system is preferred for<br />
melting furnaces and a recuperative<br />
or cold air system for casting<br />
furnaces<br />
• a pouring spout situated on the furnace<br />
tilting axis to avoid waterfalls<br />
• a furnace tilting control system<br />
Fig. 1: Revamp of melting furnace No. 5 for HAW; (a) and (b) show the situation before the revamp and (c) and (d) show the mo<strong>de</strong>rnised<br />
furnace<br />
60 ALUMINIUM · 6/2007<br />
Fotos: IST
Change language