Energy efficiency assessment: Process modelling and waste heat recovery analysis

Energy efficiency in industry is not as elevated as it should be. The aim of this paper is to present a process evaluation based on modelling as well as a waste heat recovery evaluation for a continuous heat treatment process of an Aluminium Die-Casting plant. The process is represented by production and energy dynamic (time-dependent) models combining thermal phenomena with production and economic considerations. These models allow the energy consumption, resource utilization and the production schema to be evaluated. Simulated theoretical phenomena were compared and validated with real data measurements. Once validated, the model of the heat treatment process was applied to search the best work configuration and to identify, quantify and evaluate the impact of a waste heat recovery system. Based on simulation results, their viability (energy savings or productivity increase) was quantified. The assessment shows a potential to reduce the natural gas consumption in the aging heat treatment process up to 55%, with approximately a 3-years payback period and savings of 300 MWh/year. The new working way of the process is assessed. The burners of the aging treatment process present energy reductions from 50% to 80% depending on the burner position. The new waste heat recovery system provides up to 63% of the new energy required by the aging furnace.