Abstract
The effect of hydrogen enriched of natural gaseous fuel from 100% methane to 100% hydrogen firing is numerically investigated for a tangentially fired boiler. The arrangement of gas burners, auxiliary air, closed coupled over-fire air (CCOFA) and separated over-fire air (SOFA) compartments are modeled considering upward, horizontal, and downward burner tilt positions.
A detailed computational fluid dynamics (CFD) analysis of combustible flow from the fuel and air staged burners arranged in five elevations in the furnace has been carried out to evaluate the effect of hydrogen firing on heat transfer profiles and NOx emissions at the furnace exit plane. The results show that the heat absorption in the furnace walls is increased from 6% to 10% and NOx is increased by 15 to 18 times of that of 100% methane firing when firing 100% hydrogen fuel. Higher FEGT and NOx are observed for upward firing compared to horizontal and down firing. The addition of 35% flue gas recirculation into the preheated air decreases the NOx ratio significantly for hydrogen enriched natural gas firing.
