Availability analysis of heat recovery technologies implementation in a high energy intensity industry

This research investigates the application of heat recovery technologies to capture waste heat and improve the energy efficiency of industrial processes, with a particular case in a local foundry industry in Spain. Waste heat should be reused within the industrial plant rather than emitting it into the atmosphere. The flow rates and temperatures were measured and analyzed from the waste energy streams to determine profitable heat recovery applications and processes for waste heat recovery and reuse. Amongst them, the most profound possible points for heat recovery were the waste heat from the slag of the molten process, the cooling process of the hot metal pieces inside the moulders, waste sand containing thermal energy, hot water used after cooling the induction oven, the hot wall of the maintenance ovens, the hot gases from the oven and the de-moulding process. Considering these, the main objective was thus to take advantage of the electrical energy introduced in the melting process by recovering and pre-heating the metal pieces before melting. Various technologies have proved viable - heat exchangers, Thermoelectric generators and Organic Rankine Cycle, amongst others for electricity generation from low-temperature streams and thermal energy generation. An important aspect to note is the intermittency of heat generation and, as such, the need to implement suitable storage devices to store the excess generated heat in thermal storage or electricity to the grid. Furthermore, other materials like molten salts for thermal energy storage and implementing renewable energy sources were reviewed