Исследование температурного режима элементов конструкции вакуумной электропечи сопротивления методом структурного математического моделирования

Abstract

The article demonstrates the importance of developing a structural mathematical model of a high-temperature vacuum electrical resistance furnace (ERF) for studying the thermal processes in it with determining the temperature of each furnace element, predicting the service life of heating elements, screens, and other furnace structural elements, selecting the temperature sensor installation place, and making relevant adjustment of the temperature control system. The commonly used model, in which the furnace is represented by a first-order inertial section, does not provide such possibility, because the furnace average temperature is calculated in that case. Therefore, it is necessary to construct a model based on the energy balance equations for macro elements (heater, each of the screens, loading, etc.) taking into account radiant heat transfer between the macro elements. A mathematical structural model of a Tamman vacuum high-temperature electric furnace equipped with a heater in the form of a coal or graphite pipe and thermal insulation in the form of graphite cylinders-screens has been developed and implemented in the Simulink software package. The thermal resistance of graphite screens thermal conductivity, which is commonly neglected in design calculations of widely used thin metal screens, was taken into account in simulating the thermal processes. The temperature operating conditions of individual structural elements (heaters, screens, etc.) are analyzed, both at constant power supply voltage of the heaters and in using a closed-loop temperature control system. The effect the temperature sensor installation place has on the automatic temperature control quality is shown. The advisability of using the developed model for adjusting the proportional-integral-differential controller to ensure the required control quality is substantiated.