Effects of hydrogen peroxide, sodium carbonate, and ethanol additives on the urea-based SNCR process

Abstract

The issue of secondary pollutants represents a classic problem in the urea-based selective non-catalytic reduction (SNCR) process. Therefore, this study took to investigate the evolutions of secondary pollutants when including additives during the urea-based SNCR process. Results indicated that additives, namely hydrogen peroxide, sodium carbonate, and ethanol, clear improved denitration efficiency between 750 °C - 925 °C due to the increase of OH groups. Compared to rates without any additives, the “temperature window” width of hydrogen peroxide, sodium carbonate, and ethanol increased by 30%, 30%, and 52%, respectively. The temperature at the maximum denitration efficiency was decreased by 25 °C with the addition of ethanol. The addition of hydrogen peroxide, sodium carbonate, and ethanol decreased the amount of ammonia leakage at 725 °C - 900 °C. Besides, the emissions of HNCO and N2O were decreased by adding sodium carbonate during 725 °C - 900 °C. Therefore, the addition of sodium carbonate proved to be beneficial for reducing the secondary pollutant emissions in SNCR. This study aims to provide a deeper understanding of the urea-based SNCR process in combustion.