Energy focused modeling and optimization of a radiant tube roller hearth austenization furnace
Heng, Vincent Roathy
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In this thesis, we develop a two-dimensional energy-focused model of a roller hearth heat treating furnace. The two-dimensional model is based on first-principles, detailed representations of radiation with non-participating gas and convective heat transfer. The model computes the exit temperature profile of the treated steel parts while calculating the energy consumption and efficiency of the furnace. We propose a dual iterative numerical scheme to solve the model, and validate its efficacy by simulating the dynamics of the furnace during startup and cool-down, as well as for steady-state operation. We first present two case studies to show the capability of the model in simulating the furnace system with constant fuel input to the burners. We then implement feedback control on the model to maintain furnace temperatures by manipulating the fuel feed rate to the furnace burners. A case study using suggested temperature set points from the plant details energy consumption within the furnace under control. We then use the model to find the optimal set points to minimize energy consumption while ensuring certain part temperature properties are met when part processing is complete. With optimized set points, 8.5% less energy per part is required versus the heuristic set points.