Total assessment evaluation of a cupola-based to electric induction furnace replacement

This study highlights a very important aspect of a broader effort which addresses the post-implementation follow-up of a Total Assessment Audit (TAA) performed at a mid-size Iowa foundry by the Iowa State University's Center for Building Energy Research (ISU-CBER). One of the major goals of a TAA is to analyze and document the impact of implementing energy conservation, waste minimization, and productivity enhancement opportunities at a facility. The main focus of this study is the replacement of a coke-fired cupola melting operation with one which utilizes electric induction furnaces (EIFs) instead. This work contrasts the cupola-based melting operation with the EIF-based operation. The comparison is made on the basis of production schedules, energy usage, and environmental considerations, A cost analysis based on energy utilization and labor cost differences is also presented. One of the major findings of this study was that the melting effectiveness of the EIF-based operation (i.e., the ability to provide the required heat to melt the charge components) is approximately 51% ver sus that of about 20% for the cupola. Therefore, the replacement project has not only led to a more environmentally-friendly approach but also to a more efficient and productive melting operation. In fact, despite an increase in overall electricity consumption, the overall energy consumption decreased due to the elimination of coke. The annual cost savings reflected, which include energy and labor costs, are expected to be approximately $0.0198 per pound of iron melted. This corresponds to an overall cost reduction of about 27%. The conclusions herein reported are based on data collected from utility bills before and after the replacement project and on monitoring information gathered following the installation of the two EIFs replacing the cupola. Further monitoring and analysis of this and other TAA recommendations remain ongoing as part of the above-mentioned broader effort.