Survey on monitoring of solids movement in rotary kilns

Rotary kilns are widely used in chemical and metallurgical industries. The movement of the solids through the kiln determines greatly the product quality. However, online monitoring of the solids movement is rather difficult due to the hostile running environment of the kiln. In this paper, the research and progresses on monitoring of solid movement are summarized. Several issues associated with model-based and image-based monitoring approaches are discussed with an emphasis on potential practical usages. Future studies in this field are also recommended based on literature analysis.