Energy audit experiences in foundries

Steel industry presents one of the highest energy demand of all the industrial sector. Foundries have a really relevant role both in economical terms and as regards the energy demand. The cost of energy represents several percentage points of the overall costs of a foundry. The electricity demand is very high, particularly for the induction melting furnaces. A large amount of thermal energy is obtained both from natural gas combustion and from the coal needed for the process of formation of cast iron in cupolas. Moreover the plant services must be considered: one very energy consumer is compressed air production. A not negligible weight is due to water pumping or the drying requested for eventual spray booths or the formations of moulds/cores. Every factory is different from another so that the proposal of actions of energy savings or thermal recovers requires a detailed study of each plant considering the lay out and analysing the single processes with related energy needs and thermal levels. The cooperation of the University of Padua with the Centro Produttività Veneto allowed to perform a series of energy audits in some foundries located in Vicenza province. The experience demonstrated both potential advantage of energy savings and the related difficulties, often due to the high investment costs. Anyhow the joint work of auditing between the university experts and the foundry technicians produced a better awareness on the critical points of the plant and a higher rationality level in the evaluation of investments for the renewable of the machinery. Here the method of performing the energy audits is described together with the proposals for energy savings evaluated technically and economically.