Heat Losses in Aluminum Holding Furnaces and Transfer Ladles

1. Heat Losses in Aluminum Holding Furnaces and Transfer Ladles D. Schwam, A.Stibich and E. Nielsen Case Western Reserve University

2. Energy Use in Die Casting Operations Holding molten metal is the largest energy consumer after melting

3. Aluminum Melting in Die Casting Shops Central Melter

4. Part I - Holding • OBJECTIVES • Determine the heat losses during holding • of molten aluminum. • Measure the effect of holding temperature • on the heat losses.

5. METHOD Un-Covered Covered Monitor the energy used by a 75K electrical furnace for ten hours to hold 500# of molten aluminum at set point

6. 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.

7. Amprobe AMII Pro Power Analyzer

8. Hourly Energy Use for the Covered Furnace It takes almost twice as much energy to hold the metal at 1,400oF compared to holding at 1,100oF

9. Hourly Energy Use for the Uncovered Furnace It takes almost twice as much energy to hold the metal at 1,400oF compared to holding at 1,100oF

10. 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

11. Hourly Energy Use for the Covered/Uncovered Furnace Not using a cover doubles the energy losses of the furnace at the low end 1,400oF of the range and triples them at 1,400oF

12. Part II - Transfer • 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

13. Instrumentation The transfer ladle was instrumented for real time data acquisition

14. BTU-Block Flexible

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

19. 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.