Total energy cost optimization of industrial paint drying oven in steel strip production with extremum seeking control

Heavy industry facilities try to find ways to minimize energy costs, one of the most important costs of production, in order to compete in the market. In this study, an applied cost optimization was performed on a real furnace system used in a steel strip production line. Furnace systems consume different energy sources at the same time. Therefore, energy cost optimization is a necessary study for furnace systems. The actual kiln system studied in this study consists of two zones and each zone consists of eight parts. For continuous heating of the steel strips, a natural gas burner and a 45kW circulation fan are placed in each zone. A slope-based Extreme Seeking Control (ESC) has been developed to minimize the total cost of the heating process by optimizing the fan speeds in the furnace system without changing the furnace structure and internal burner control setup. Improved ESC has been applied in steel strip production, overcoming constraints such as furnace safety, meter characteristics, and stability delays. The energy consumption values measured by applying ESC and the energy consumption values obtained with the settings recommended by the oven manufacturer were compared in terms of cost. At the end of a real production, the developed ESC showed that the same product can be produced with less total cost at different operating speeds of the fans. The total cost of electrical energy and natural gas was reduced by 3.44% when 78% was used instead of the machine manufacturer's recommended 70% fan speed. It is envisaged that the savings can be further increased if the natural gas consumption of each zone of the furnace system is measured separately.