Considerations for Using Solar Rotary Kilns for High Temperature Industrial Processes with and Without Thermal Storage
Abstract
In this work, technical considerations and a comprehensive discussion on solar rotary kilns are reported. Rotary kilns permit to obtain well-mixed particles in a broad range of temperatures (up to 2000°C), and, for this reason, they are widely used for treating solid particles in several industrial sectors. In solar research field, they have been employed for processing materials in solar furnaces and, in some cases, they have also been proposed as receivers in solar tower plants. The aim of this work is to investigate the potential of solar rotary kilns as thermal receivers in solar tower plants, taking into account the constraints that limit their use. In particular, because of the shape of these reactors, circular heliostat fields are not allowed and the maximum power of the receiver is limited to less than 100 MWth. Thus, the reference case of a 50-MWth central tower plant for the heating of sand as heat transfer medium is reported. Residence time and receiver thermal efficiency are evaluated using an analytical method. In addition, two possible heliostat fields with different size of mirrors are also proposed.
Keywords
Concentrating solar heat, Rotary kilns, Industrial applications, Scaling-up, Thermal storage