Review on Reaction Mechanisms of Sulfur Species During Coal Combustion

Abstract

Various low-NOx combustion technologies have been widely applied as primary measures to limit NOx emission in coal-fired boilers. However, this leads to the formation of high concentrations of H2S in the fuel-rich zone and thus causes high-temperature corrosion of the water-wall. In order to suppress the formation of H2S near the water-wall, it is necessary to have adequate knowledge of the reaction mechanisms of sulfur species during coal combustion. Therefore, this work systematically reviews the current state-of-the-art concerning reaction mechanisms for sulfur species, including global mechanisms, detailed mechanisms, and reduced mechanisms. Additionally, two operation techniques, namely, near-wall air and multi-hole-wall air, are introduced to avoid high-temperature corrosion caused by H2S. Finally, some new research directions are recommended to further reveal the reaction mechanisms of sulfur species and to test the feasibility of multi-hole-wall air on preventing high-temperature corrosion.