Mathematical modeling of a heat treatment furnace and tuning of cascaded temperature control loops

This paper describes an approach for tuning the Proportional Integral Differential regulators used in temperature control of a gas heat treatment furnace for metallurgy. The volume of the furnace, 600 m3, makes it very difficult to control the temperature on the treated metal piece. A mathematical model, based on primary physical relations between the measured and the controlled variables, was built in order to simulate a process which takes around 40 hours, with response times of minimum 15 minutes.