Investigation on SO2, NO and NO2 release characteristics of Datong bituminous coal during pressurized oxy-fuel combustion

The release behaviors of SO2, NO and NO2 of Datong bituminous coal during the pressurized oxy-fuel combustion were studied by pressurized thermogravimetric analyzer combined with Fourier transform infrared spectroscopy, which mainly focused on the effect of pressure to the emission characteristics. The experimental results demonstrated that more pyrite could be converted to the sulfur precursors and then oxidized to SO2 with increasing pressure up to 2 MPa. However, because the conversion of SO2 to SO3 probably was accelerated at 3 MPa, the conversion rate of fuel-S to SO2 decreased to some extent. Along with the increase of volatiles yield at elevated pressure, more volatile-N released during devolatilization converted into NO which led to an increase of NO emission. With increasing pressure from 0.1 to 2 MPa, the conversion value of fuel-N to NO2 increased gradually due to the elevated oxygen partial pressure. But the NO2 emission declined somewhat at 3 MPa due to the accelerated decomposition rate of NO2 at higher combustion temperature. The NOx (NO and NO2) emission under pressurized oxy-fuel atmosphere monotonously increased with increasing pressure.