Product-service System for Sustainable EAF Transformers: Real Operation Conditions and Maintenance Impacts on the Life-cycle Cost

摘要

Steel industry is one of the largest energy consumers in the manufacturing sector and covers a great share of the total energy consumptions in the world. As in recent years, energy efficiency has been a top priority for the European Commission, which set a reduction of 20% as a target for the energy consumption, so that great improvements in energy performances are required. Many improvements have already been introduced in the Electric Arc Furnace (EAF) process and additional progresses are very difficult to be achieved. Consequently, the main opportunity consists in the improvement of other system components, especially of the transformer's performance, as it is an expensive component with a strategic relevance for EAF operation. A more energy-efficient transformer can make a valuable contribution to European energy savings: lower energy losses substantially correspond to lower running costs. However, recent EAF transformers from different firms have become equally well performing, thus, the basis of the competition has been shifted from the single product offered to a customized solution that should fulfill specific customer needs. In other words, in order to obtain an advantage on the main competitors, some additional services, that are needed during the use phase of the product, are added. These extra services take into account the real energy losses obtained during the operation of the EAF and the maintenance activities. To perform the economical analysis of the solution, it is thus necessary to calculate the EAF transformer's life cycle cost (LCC) or total cost of ownership (TCO), over the life span of transformer. At the present, no works have been conducted on the EAF transformer which are exposed to more critical conditions than power/distribution transformers, and no real conditions have been considered even for other forms of transformer. In addition, the only aspects that have been taken into account in the existing transformer's LCC were the purchasing price and a share of the total relevant costs of losses (no-load and load losses). Thus, the aim of the present work consists in the evaluation of a solution consisting of a tangible product (EAF transformer) and intangible services (e.g. maintenance activities, operational consultancy) that best satisfy the EAF operations’ requirements, in order to simultaneously enhance competitiveness and support sustainability. Moreover, the other relevant contribution is the integration of maintenance aspects and failure risk, as design decisions affect also transformer's reliability and related maintenance activities.