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Show Scrap Preheat System Cuts Melting Costs A scrap preheating system designed for use with electric induction furnaces reportedly can reduce melt shop furnace energy consumption by up to 15%, enhance melt- Looking downward at the turntable. The far bucket is being loaded with scrap; the scrap-charged bucket on the right gets preheated (the white shroud protects the burner); the preheated near bucket is removed and transported to the furnace for emptying; an emptied bucket is replaced on the left of the carousel to await the next recharging cycle. ing capacity, and eliminate in-plant smoke and airborne emissions. The system was developed jointly by the Canadian Gas Research Institute, Toronto, Ontario, Canada, R. J. Cyr Co., Windsor, Ontario, and Standard Induction Castings, Windsor, in response to the increased competitive pressures necessitating cost reductions and more stringent regulatory controls on air emissions faced by the metalcasting industry. The first commercial application of the system was installed in December 1995 at Standard Induction Castings, where it replaced a traditional vibratory pan pre-heater system. Standard Induction Castings, in business since 1965, is a producer of gray and ductile iron brackets and hollow bodies for the automotive, heavy truck, industrial machinery and pump equipment markets. The company induction melts about 80 tons of metal daily and employs 120 people. Of R. J. Cyr's preheat system Standard's Greg Lavallee reports that since the installation their unit energy costs have been reduced, and "additional unanticipated environmental benefits have been realized," thereby improving the company's relationship with the Ontario Department of the Environment At the heart of the Cyr system is a highly efficient gas burner that preheats buckets of scrap feedstock to an av- ROUNDUP erage temperature of 800°F. The scrap bucket rests on a circular turntable. W h e n it is full, the turntable rotates 90° and positions the bucket under the burner head, which is then automatically lowered about 6 inches to meet the bucket top. Beneath the bucket is an opening that leads to exhaust air piping. The burner head, insulated scrap bucket, and exhaust air create downward closed loop air circulation. The burner produces a diffuse flame that heats the surrounding air, which is then drawn through the scrap-filled bucket by an exhaust fan and then out through the afterburner. Because the closed system is maintained at negative pressure, any leakage is inward to the system, not outward to the foundry environment. The exhaust gas and fumes travel to the afterburner, where airborne contaminants are oxidized and exhausted to the atmosphere, thus ensuring compliance with environmental regulations. Preheated scrap is emptied from bucket into induction furnace. Through use of the space-saving turntable design, near-continuous production rates are achieved and productivity is improved. W h e n the system is in operation, one bucket is being preheated, one is being emptied into the furnace, one is waiting, and one is being filled with scrap. After a bucket of scrap is preheated, the burner head lifts up and the turntable transports the bucket to the pickoff point. An operator hoists the bucket, moves it along a powered overhead monorail, and empties the charge into the furnace. W h e n the next bucket is ready the cycle repeats. By making scrap preheating nearly continuous, the new system cuts overall cycle time to less than seven minutes. The system offers a low cost alternative for induction furnace operators to improve energy efficiency and production rates. FOUNDRY MANAGEMENT & TECHNOLOGY October 1997 |