Environmental Engineering Reference
In-Depth Information
Designing procedure for a high performance aluminum melting furnace
Design specifications
Usage (rolling, extrusion, casting)
Furnace capacity (ton/ch)
Ingot ratio (ingot + return material)
Utilities (fuel, compressed air, water)
Choice of furnace shape
Furnace type (crucible, tower, stationary, tilting)
Layout
(charging
door,
dross
discharging
chute,
holding furnace)
Decision of furnace size
Melting capability (ton/h)
Furnace inner size (furnace floor area,
bath depth,
combustion room)
Material charging tonnage (ton/ch)
Heat Balance
Choice
of
combustion
Melting capability (ton/h)
Burners (capacity, number)
NOx (less than 130ppm)
Burner tilting (reduction of consumption/ melting time)
device
Choice of refractory
Treatment temperature (740 to 760 C)
Purity of aluminum
Control items (number of zones, fuel control, furnace
pressure control)
Control system (flow control, ON-OFF control)
Choice
of
control
de-
vices
Choice of other auxiliary
devices
Bubbling plug (reduction of metal loss by 0.8%)
FIGURE 5.78
High performance aluminum melting furnace design procedure.
• Concentrated collision flame oil burners (F1) (NO
x
lower than 100 ppm,
converted O
2
12% mol). This type uses high velocity jet flow (high momen-
tum), indispensable for melting, and in parallel two-stage combustion and
combustion gas self-circulating system. This type of burner can easily meet
the regulated NO
x
levels. It also has a high combustion performance.
•
Distributed collision flame oil burners (F2) (NO
x
lower than 50 ppm):
Because the fuel is blown from outside the combustion air, the flame
temperature is lower; thereby NO
x
is lower than in the two-stage com-
bustion type of burners. However, the combustion performance at the low
temperature zone is somewhat questionable.
Finally, by blowing in treatment gas from porous plugs in the furnace floor, the
separation of slag from the bath and drying of the slag are carried out to reduce
metal loss incidental to the removal of the slag. By agitating the bath, thereby
breaking the thermal layer, the metal loss attributable to the oxidation by the exces-
sively high temperature of the bath surface is also reduced.
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