(67b) Study of Temperature Profile in the Agitated Bed of Pilot Scale Externally Heated Rotary Kiln

Experiments were carried out in a steel drum of 0.6 m in diameter and 0.45 m in length. Quartz sand of size 0.2 mm and copper cylindrical particles of size 0.8 mm were used for the experiments.

The drum wall was electrically heated from the outside. The temperature profiles in the agitated solid bed were measured with eight thermo elements which rotated with and periodically immersed in the bed. On the basis of these temperature profiles a bulk temperature was estimated with which the heat transfer coefficient was defined.

Temperature fluctuation of the kiln wall decreases as the kiln speed increases. It has been observed that the temperature profiles of the solid were independent of electrical heater position. Heat transfer coefficient obtained from the experimental data for quartz sand is in the range of 100-350 W/(m²K) and for 0.8 mm cylindrical copper pellets is in the range of 300-500 W/(m²K). Heat transfer coefficients increase with rotational speed.