NO Emissions from Oxidizer-Staged Combustion of Superfine Pulverized Coal in the O₂/CO₂ Atmosphere

Abstract

The CO₂ control technologies have been studied extensively in recent years, among which the oxy-fuel combustion shows a vast number of advantages to be explored commercially in the near future. However, unexpected problems, such as bad combustion characteristics and serious slagging and depositing issues, show up with the replacement of N₂ by CO₂. These inherent disadvantages in normal O₂/CO₂ combustion can be restrained via combining the superfine pulverized coal and oxy-fuel combustion technology. The axial NO emission characteristics of this new technology were focused here. The effects of the oxidizer staging were also studied in detail. Results indicate that the axial NO emissions of the unstaged O₂/CO₂ combustion basically showed “M” type of distributions along the furnace. The “M” type can be divided into the main homogeneous and heterogeneous reaction zones. The oxidizer-staged O₂/CO₂ combustion can mitigate NO emissions effectively. Coals with smaller particle sizes and higher volatiles are more advantageous for eliminating NO in the staged O₂/CO₂ combustion technology. The superfine pulverized coal used with certain low NO combustion technologies shows significant superiority in both combustion performance and NO abatement