Use of rotary kilns for solar thermal applications: Review of developed studies and analysis of their potential

Rotary kilns have a long history of use in classical industries. They are able to achieve high temperatures with higher thermal efficiencies than other reactor types. Their performance has been widely studied and classified according to different parameters. Since it is a well-known technology, rotary kilns have been selected for high temperature solar processes. This article initially presents a brief review of the rotary kiln technology and it focuses on the employment of these devices for thermal and thermochemical processes conducted by concentrating solar energy. Among the solar devices, a novel rotary kiln prototype for thermochemical processes is presented and compared with a static solar reactor. Finally, some practical conclusions on the design and operation of solar rotary kilns are remarked and an analysis of their main limitations is presented.The authors acknowledge the financial support provided by the FONDECYT project number 3150026 of CONICYT (Chile), the Education Ministry of Chile Grant PMI ANT 1201, as well as CONICYT/FONDAP/ 15110019 ‘‘Solar Energy Research Center” SERC-Chile. Also, the second author wish to thank to the Plataforma Solar de Almería and the University of Almería for the collaboration and assistance devoted to the development of his Ph.D research