Experimental Study of NO Formation in a High-Steam Atmosphere During a Pressurized Oxygen-Fuel Combustion Process

Pressurized oxy-fuel combustion is considered to be one of the most promising carbon capture technologies due to its low energy consumption and high carbon capture rate. Part of the combustion-supporting environment is composed of circulating flue gas, so the concentration of steam in the carrier gas is higher than that of conventional combustion. However, as an important factor in this technology, steam has not been mentioned in the vast majority of studies. In this study, combustion experiments simulating wet flue gas recycling were performed in a pressurized tube furnace to analyze the effects of the steam ratio (0-40%), oxygen concentration (21-50%), and pressure (0.1-0.6 MPa) on the formation of NO . The results show that increased system pressure significantly inhibits NO emissions during the oxy-fuel combustion process. Meanwhile, the increase of the injected steam concentration enriches the various radical pool compositions in the carrier gas, inhibiting the formation of NO and N₂O. In contrast, the increase of the combustion temperature promotes and inhibits the formation of NO and N₂O, respectively, during oxy-fuel pressurized combustion. Moreover, elevated oxygen concentration enhances the oxidation of the carrier gas, leading to an increase in NO emissions.