Rotary Kiln, a Unit on the Border of the Process and Energy Industry-Current State and Perspectives

A rotary kiln is a unique facility with widespread applications not only in the process industry, such as building-material production, but also in the energy sector. There is a lack of a more comprehensive review of this facility and its perspectives in the literature. This paper gives a semi-systematic review of current research. Main trends and solutions close to commercial applications are found and evaluated. The overlap between process and energy engineering brings the opportunity to find various uncommon applications. An example is a biogas plant digestate treatment using pyrolysis in the rotary kiln. Artificial intelligence also finds its role in rotary kiln control processes. The most significant trend within rotary kiln research is the waste-to-energy approach in terms of various waste utilization within the process industry or waste pyrolysis in terms of new alternative fuel production and material utilization. Results from this review could open new perspectives for further research, which should be focused on integrated solutions using a process approach. New, complex solutions consider both the operational (mass calculations) and the energy aspects (energy calculations) of the integration as a basis for the energy sustainability and low environmental impact of rotary kilns within industrial processes.

Automated summary

This paper provides a semi-systematic review of rotary kilns, their applications, and current research trends. It highlights the opportunities for uncommon applications, such as pyrolysis in rotary kilns for biogas plant digestate treatment, as well as the integration of artificial intelligence in control processes. The waste-to-energy approach and waste pyrolysis emerge as significant trends within rotary kiln research. The results of this review open up new perspectives for further research on integrated solutions that consider both operational and energy aspects for the sustainability and environmental impact of rotary kilns.