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Heat transfer in rotary kilns: a retrospect

While working at the Research Institute of the Cement Industry (the German Cement Works Association) Paul Weber received his doctorate (with distinction) from Clausthal-Zellerfeld in 1959. His doctoral thesis was, “Heat transfer in the rotary kilns with due regard to Cyclic Processes and Phase Formation.” Weber's investigation stands as a testament to rigorous application of first principle thermodynamics. In his own words, “to achieve further improvement of the economy and the design of cement kilns, it is necessary both to know the theoretical principles underlying the heat transfer in the rotary kiln and to know the heat requirement of the material constituting the kiln charge.” Paul Weber was the first to identify the causes of variations in thermal efficiency between kilns of the same type as well as kilns of different designs. More than fifty years after its first publication, this reference is still one of the foundational references in cement manufacturing. A review of Weber's work and suggestions for further applications using advances in analytical techniques are presented.