Case study of energy recovery in workshops using induction heating systems

Abstract

International audienceThe aim of this study is to improve the energy efficiency of an industrial process including an induction heating device by recovering fatal losses coming either from inductor Joule losses or from heated pieces after treatment. Software tool based on the pinch method was developed in Modelica language. A specific model for the induction heating device was written, taking into account the temperature dependence of the thermal properties of the heated metal and of the heating efficiency of the induction device. The collected energy can be reused in relay of a boiler inside the process line for heating pickling baths or washing baths or for space heating or domestic hot water production. It can also be converted into electricity (Organic Rankine Cycle, thermoelectricity). In this paper, the authors present case studies realized in a typical steel forging workshop and in a cast iron foundry. They show that direct reuse of the thermal energy has a payback around 3 years. It requires a coil cooling circuit at high temperature (typically 70 to 300 °C). The conversion into electricity is not relevant because of a very long payback