Heat Losses in Aluminum Holding Furnaces and

Transfer Ladles

D. Schwam, A.Stibich and E. Nielsen Case Western Reserve University

Energy Use in Die Casting Operations

Holding molten metal is the largest energy consumer after melting

Aluminum Melting in Die Casting Shops

Central Melter

OBJECTIVES

• Determine the heat losses during holding of molten aluminum.

• Measure the effect of holding temperature on the heat losses.

Part I - Holding

METHOD

Monitor the energy used by a 75K electrical furnace for tenhours to hold 500# of molten aluminum at set point

Covered Un-Covered

Fig. 4 IR image covered Fig.5 IR image uncovered

Infra-Red Images of the Holding Furnace

The exposed area of the molten metal is three sq. ft.Some losses occur even with the cover in place.

Amprobe AMII Pro Power Analyzer

Hourly Energy Use for the Covered Furnace

It takes almost twice as much energy to hold the metal at 1,400oFcompared to holding at 1,100oF

It takes almost twice as much energy to hold the metal at 1,400oFcompared to holding at 1,100oF

Hourly Energy Use for the Uncovered Furnace

Hourly Energy Use for the Covered/Uncovered Furnace

The uncovered furnace holding at 1,400oF uses almost five times (!)more energy compared to the covered furnace holding at 1,100oF

Hourly Energy Use for the Covered/Uncovered Furnace

Not using a cover doubles the energy losses of the furnace at thelow end 1,400oF of the range and triples them at 1,400oF

OBJECTIVES

• Determine the heat losses during ladle transfer of molten aluminum.

• Evaluate the effect of improved ladle insulation

• Assess the impact of continuous vs. interrupted ladle use on heat losses

Part II - Transfer

Instrumentation

The transfer ladle was instrumented for real time data acquisition

BTU-Block Flexible

The cooling rate for the insulated and covered ladle is cut by half relative to the uninsulated and uncovered ladle

CONCLUSIONS

• The “insulated” ladle had a smaller temperature loss whether both ladles were started cold or in the middle of continuous cycles. • During the stationary cooling curve test the “insulated” ladle outperformed the “standard” ladle by 139% in reducing the temperature drop during the first twenty minutes. • The performance of both ladles improved noticeably as they were used repeatedly without significant down time. • Adding a cover to an insulated ladle can cut the heat lost during a twenty minute transfer cycle by nearly half, compared to a “standard”, non-insulated ladle.