Control of a ceramic tiles cooling process based on water spraying

Abstract

The control of the surface temperature of ceramic tiles in a real industrial production line is developed. The process consists of a transportation band that carries the hot tiles through a water sprayer whose objective is to reduce its temperature. Two input signals can be modified: the velocity of the transportation band and the flow rate of the sprayer. In order to control the outlet surface temperature, the quantity of water deposited (and hence evaporated) per tile, that is a static function of the velocity and the flow rate, is used as the control input. The inlet temperature has a tile to tile fast pattern variation and a slow average change. First, the experimental identification of the process model is carried out. Then a feedback PI controller based on the measurement of the outlet temperature is then tested, showing a good average tracking, but a poor compensation of the fast variations. An adaptive feedforward control based on the measurement of the inlet and outlet temperatures is developed and also tested in the plant, showing a much better performance, but a higher cost. Finally, a disturbance observer based feedforward control is tested, showing an intermediate performance and cost. © 2009 Elsevier Ltd. All rights reserved.