Energy efficiency and line productivity improvements for a continuous heat treatment process

Panel: 4. Technology, products and system optimisation

This is a peer-reviewed paper.

Authors:
Iñigo Bonilla Campos, IK4-IKERLAN, Spain
Nerea Nieto Aguirrezabala, IK4 Ikerlan, Spain
Luis A. del-Portillo Valdes, UPV-EHU, Spain
Bakartxo Egilegor Ezenarro, IK4 Ikerlan, Spain
Haizea Gaztañaga Arantzamendi, IK4 Ikerlan, Spain

Abstract

The industry sector in Europe reaches 35% of total energy consumption. Energy-intensive industries (as die-casting, refining, concrete) are liable for more than half of that consumption. Commonly, these industries are mainly focused on reaching the desired levels of production without considering the energy efficiency along the process. However, current data acquisition methods are revealing new room for improvement which should be analyzed. Energy efficiency in industry is not as high as it should be. Models, researches and experience, situate the level of the hypothetical energy efficiency in the manufacturing sector many points above the current state. This research explores and analyses a representative heating process in order to improve its productivity and energy consumption. The aim of this paper, which focuses on analyzing energetic and productive variables, is to present energy efficiency and line productivity improvements for a continuous heat treatment process of an aluminium die-casting plant by means of an integral modelling methodology which includes a sensitivity analysis. Solution, quenching and aging processes were represented by productive and energetic time-dependent models combining thermal phenomena with techno-economic considerations that allowed energy consumption, resource utilization and the working way to be evaluated. Simulated theoretical phenomena were compared and validated with real data measurements.

A virtual model of the heat treatment process was applied to search the best work configuration and to identify, quantify and evaluate proposed improvements. Based on the simulation results, both technical furnace modifications and productive improvement actions were identified; and their viability, impact and resulting energy savings or production increase were quantified. For instance, a waste heat recovery system from solution to aging furnace, by a novel heat exchanger (heat pipes) was analysed, reducing, as consequence, the natural gas consumption from the heat treatment up to 14%, with approximately 3-years payback period and savings of 512 MWh/year. Besides, other modifications in tactical or operative working way (without investment cost), such as modifying batches entry, were evaluated, with production improvements between 5% and 10%.

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