Transformation mechanism of C and N during rapid devolatilization of pulverized coal particles under the pressurized atmospheres

Pressurized O₂/CO₂ combustion technology is a new power generation technology that can achieve CO₂ capture efficiently. In this study, we investigated the pressurized devolatilization of Shenhua bituminous coal in a pressurized drop tube furnace experimental system at 1273 K. The evolution mechanism of carbon/nitrogen gas–solid products during the pressurized devolatilization process was analyzed using online measurements and offline analysis. We found that increasing the pressure from 0.3 to 1.2 MPa promoted the emission of CO and inhibited emission of NO. N₂O emissions were insensitive to the change of pressure, and NO₂ emissions were almost zero under the experimental conditions. The introduction of CO₂ decreased the production of NO_x and primary sources of nitrogen-containing gas-phase products were N-5 and N-6 active groups. Therefore, pressurized O₂/CO₂ combustion technology can effectively reduce NO_x emissions in the devolatilization of pulverized coal and impact the subsequent char-combustion process.