The Implementation of an Algorithm For Temperature Estimation in a Rotary Drier

During the production of Light Expanded Clay Aggregate (LECA), moist clay is fed into a rotary drier where pellets are formed and dried by a counter current of hot gas. The drying process is controlled using an estimated feed temperature at the end of the drier. The temperature is estimated using the measurement signal from a thermocouple installed at the inside of the drier wall. Due to the drier´ s rotation the thermocouple is alternately heated in the gas and cooled in the feed. Thermal capacities around the thermocouple prevent it from reaching a stationary measurement value during the time it is in the feed. The thermocouple response in the feed phase is approximated to a first order step response model. The stationary measurement value is estimated using an extended Kalman filter.