Numerical Simulation Study On Low NOx Emissions Combustion In A300MW Tangentially Fired Boiler

With the sustainable development of Chinese economy, energyconsumption has been increasing year by year, and as a result, NOxemissions increase rapidly. Atmosphere pollutants (especially NOx)produced by coal-fired power plants need to be controlled, and how tocontrol NOx emission has become the focus of attention.Using a commercial software, the flow field, heat transfer andcombustion process in a tangentially fired furnace of some300MWpulverized coal-fired boiler was investigated numerically. In this paper,RNG k turbulence Model is used to simulate gas-phase turbulenttransport. The P-1Radiation Model is used to calculate the radioactive heattransfer, and particle tracking is calculated by Stochastic Model, volatileevolution is calculated by Two Competin Rate Devolatilization Model andchar combustion is calculated by Kinetics/diffusion-limited RateModel.The NOx formation is calculated by Post-processing method.NOxformation in conventional burner and six improved conditions(mainly fordifferent CCOFA proportion,different SOFA layout height, horizontalconcentrated-thin combustion and deflected second air system) ispredicted.The simulation results show that: within a certain range, as CCOFAproportion increase, NOx emissions decrease. The SOFA layout height hasgreat impact on NOx formation characteristics. With the SOFA layoutheight increases, the overall emissions and peak value of NOx decrease.But the SOFA layout height has a optimum value.Horizontalconcentrated-thin combustion can reduce NOx emissions effectively.Deflected second air system can effectively control NOx emissions of furnace. NOx emissions of furnace can be reduced to318mg/m3and500mg/m3when calculated coal is bituminous coal and anthracite.Airstaged combustion technology is an effective way of controlling NOxemissions.