Protection System for a Solar Calciner Window Using Electrostatic Separation of Particles

Abstract

In the recent years, the development of solar calciners has gained interest, as these reactors: i) avoid fossil fuel emissions, and ii) facilitate the implementation of solar calcium looping for carbon capture. Due to the high calcination temperature, (usually around 1173 K depending on the carbon dioxide concentration), reactor concepts that offer direct particle irradiation show some advantages compared to indirect heated concepts, such as the avoidance of additional heat transfer steps or the possibility of using cheaper materials, i.e. lower temperature limits. To achieve controlled atmosphere conditions in direct irradiated reactors, a window can be used to close the aperture. However, the major challenge of treating solid particles in a solar reactor with window is to avoid particle deposition on this component. Particle contamination leads to a decrease in the transmissivity of the window, causing overheating and window fail-ure. Several studies have been carried out to address this problem, proposing solutions based on aerodynamic protection. These systems mitigate the problem for other thermochemical pro-cesses, but involve a large amount of sweep gas, and in several cases particle contamination continued to be reported. Most previous studies evaluated the performance of window protec-tion using qualitative methods only (e.g. visual observation), but quantitative results are rarely reported. This work carries out an experimental evaluation of an innovative window protection system that uses electrostatic precipitation of particles (ESP) to prevent the migration of solid particles to a reactor window.