Simple Solutions That Work! Issue 12

19 BACK TO BASICS the main chamber from the well charge area. 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 Btu’s/# or 1500-1700 Btu’s/# melted. FUEL FIRED LOW HEADROOM FURNACE At the Schaefer Group 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 transfer in melting aluminum is accomplished through radiation, we have made this aspect central to our design. Using a series of highly radiant burners evenly distributed in the roof we bring this radiant heat source closer to the bath than other furnace manufacturers. Having the heat source close to the bath greatly increases the efficiency of the Schaefer design. We overcome the obstacle of a lower roof by having cleaning access to the main chamber at both ends of the furnace. On many furnaces we then add component aspects that some of the other furnaces’ types have, depending on our customers particular needs. Many of our units have a preheat hearth at one end. This feature allows for sow and ingot loading at one end in a manner without the metal losses that occur in a dry hearth as we draft the waste gasses across the sows minimizing the metal losses. Once they sweat then they are pushed into the hot metal bath where the stored Btu’s in the aluminum help finish the melting process. We also add external side wells that allow easy charging of returns, gates and risers back into the furnace. We combine this with a properly sized circulation pump for the greatest available efficiency in well melting. When we combine all the best features along with a properly insulated lining you end up with a furnace that has an efficiency of from 1230 to 1500 Btu per hour fuel usage when melting and a furnace that provides or minimal metal losses (3-4%). ELECTRIC HOLDING AND MELTING FURNACES The Schaefer Group is the inventor of the electric radiant reverb, supplying the first unit in 1974. Electric melters and holders have far lower metal loss than a fossil fueled furnace either at or below 1%. Melting can be accomplished at .20 -.23 kW which equates to approximately Low Headroom Melter Electric “in cell” melter Continued on next page