59 The wave of the future looks to be in electric melting and holding. This paper will give you all the pros and cons to electric melting of aluminum. It will include the latest technology for electric reverbs and immersion element furnaces that both melt and hold metal. Discussions on ROI and actual energy savings, metal melt loss and maintenance will be covered. What is “green technology”? It is categorized as a non-fossil fuel, using alternative energy sources such as solar, wind, water and geothermal. And, electric energy! Using electric energy in melting aluminum in foundries and die casters, not only reduces carbon footprint and emissions, but it also positions many of them beyond the scope of clean air regulations. With mandatory reporting of yearly emission output to the EPA already in place, this paper will delve into a thorough examination of different electric melting and molding furnaces, comparing their efficiencies to traditional fossil fuel-fired units. ELECTRIC REVERBERATORY MELTING FURNACES Highly efficient electric radiant roof furnaces provide the highest quality metal on the market today. These furnaces stand out by eliminating the gassing of metal with products of combustion, ensuring a cleaner melt. The Schaefer Group designed and built the first electric roof reverb in 1974 and since that time has become many melters’ first choice for low-cost production of clean high-quality aluminum. The electric version of the radiant roof furnace is controlled by a reliable solid state power control unit. The temperature controller is a 1.4% accuracy single loop microprocessor with full proportioning features. This allows for very close temperature control avoiding the widely fluctuating ‘on-off’ system. The control panel is completely automatic and comes with a set of high-low alarm functions to assure you of proper casting temperatures. If the furnace should over-heat to a preset alarm level the panel will shut down. An alarm-type control thermocouple will sound an alarm in the event of a thermocouple protection tube leak. Energy usage in the gas fired furnace is extremely low. As an example, a 2,000-pound capacity holder at 1250° F will use approximately 25 BTU/lb/hr to hold with the well covers on. For an electric low energy holder under the same condition, it is 0.00205 kW/lb/hr. Silicon carbide resistance elements transfer radiant heat to the workload to melt with only .23 - .25 kWh/lb. Metal melt loss is less than 1% when charged evenly. If we take that fact alone, you can get a relatively short payback on this melter. From a furnace efficiency standpoint, they are about 67% efficient. Gas fired furnaces are at best 37% efficient unless you put heat exchangers or regenerative burners on them. TECHNICAL TOOLBOX ISSUE DAVID WHITE Co-Owner D and S Consulting LLC ARTICLE TAKEAWAYS: • Electric melting & holding of aluminum for reducing energy • Pros and Cons with electric melters and holders • How to calculate energy savings ELECTRIC MELTING: THE NEW “GREEN TECHNOLOGY” FURNACE Continued on next page HERE ARE THE REAL EFFICIENCY NUMBERS: ELECTRIC RADIANT ROOF ELECTRIC REVERB 750 BTU/LB 66.7% WITH MOLTEN METAL CIRCULATION 687 BTU/LB 72.8% IMMERSION ELEMENT MELTER WITH MOLTEN METAL CIRCULATION 655 BTU/LB 76.3%
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