18 foundry of the future using electric melter holders at the machine to give high-quality inclusion-free aluminum to the machines. Fuel Fired Stack Melters This type of furnace is typically used for ingot and scrap melting only. This design is an offshoot of dry hearth as the ingot are loaded into a tall tower (stack) type flue where the stack is supposed to be kept full. At the bottom of the stack is a sloped dry ramp and usually opposing burners firing directly at the stacked-up ingot and scrap. The spent gasses co-mingle with the balance of the ingot and scrap stacked up in the tower. This allows the flue gases to transfer their heat into the load prior to exiting the furnace at a lower temperature than most other types of furnaces resulting in greater utilization of heat energy. The efficiency of these types of furnaces ranges from 900 to 1100 Btu per pound. Even though they hold less than reverbs typically hold they still take up about as much room because of their loading mechanism attached to the stack to carry the scrap and ingot up to the top of the stack and dump it. Stack melters if charged properly will be in 3% melt loss. If lightweight density scrap is charged or the furnace is not charged timely then this can increase to 5~7% or more metal melt loss. Fuel Fired High Headroom Reverbs Most reverb furnaces are closed box type furnaces with a bath depth of around 22-30 inches. Many have high side walls and the dimension from the molten bath to the to the underside of the roof is 4 feet or greater. These higher walled furnaces have tall door openings and usually wall fired burners. These burners usually are convective and depending on the type can cause agitation of the metal as they are trying to push the heat into the metal. The efficiency of these types of furnaces ranges from 1700 to 1900 Btu per pound. Many in the extrusion industry use this type of furnace as they have rejected extrusion sections, they need to charge that are bulky. This is commonly known as a batch melter. Most secondaries use these furnaces because of their capability to melt a lot of metal sizes range from 80,000# capacity to 250,000# and more. It is advisable to circulate the metal in these large furnaces to keep the metal more homogenous and the alloying agents in solution. Sometimes these are referred to as Side Well Melting Furnaces taking its name from an external well that either scrap or return parts or gates and risers are charged into. These types of furnaces or versions similar are found in the die casting, foundry, and secondary industry. The external well is an ideal place to charge dirty scrap and thin sections as there is a greatly reduced metal loss when these items are melted by submersion into a molten bath versus being exposed directly to the products of combustion or direct flame impingement. The other benefit is that the coatings and volatiles are burned of in the external well that is hooded and ducted to a baghouse. Further, as most well melters have submerged openings to allow circulation of the hot metal to the well the drosses, oxide and residue from the dirty scrap remain in the well and do not enter the main chamber. The dross and residue are easily skimmed from the well metal surface. The main chamber therefore remains a little cleaner. Most of these units are as well side wall fired and have high side walls. To augment the heat transfer, the use of a molten metal circulation pump greatly increases the efficiency of these types of furnaces. The hot metal from the main chamber is pushed across the cold charge in the well greatly increasing the melt rate. With circulation you can gain about 200 Btus/lb or 1500-1700 Btus/lb melted. • With Recuperation system added = 1,095 Btu/lb • With Regenerative burners added = 940 Btu/lb Fuel Fired Low Headroom Furnace We have spent many years refining our more efficient type of reverbatory furnace with a lower clearance from the molten bath to the underside of a radiant fired roof. As the majority of all heat
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