Numerical simulation of the heat transfer and NOX emissions in a 660 MW tangentially fired pulverised-coal supercritical boiler

Numerical simulation of the influence of operating conditions of the furnace on its performance characteristics like heat flux distribution, Furnace Exit Gas Temperature (FEGT) and NOx emission levels was performed for a tangentially fired pulverised coal boiler. The results revealed that the FEGT and NOx emission are slightly higher when the top seven coal nozzles are in operation compared to the bottom seven coal nozzles. While the increase in burner tilt led to an increased FEGT, the least NOx emission was obtained for the burner tilt with 0°. The NOx emission started to increase with both increase and decrease in tilt from 0°. In addition, the FEGT and NOx emission were directly and inversely proportional to the percentage of SOFA (Separated OverFire Air) opening respectively. NOx emission was lower by around 7.5% when the air staging was done with the top-most SOFA nozzle instead of the bottom-most SOFA nozzle. However, the FEGT was higher in the former case.