文摘
Experiments with a small-scale furnace for a down-fired pulverized-coal 300-MWe utility boiler were carriedout on a single-phase test facility to investigate the influence of different secondary air distributions on theaerodynamic field in the furnace. When the secondary air flux of tier E increased within a suitable range, itdid not reverse the fuel-rich flow or shorten the residence time of coal particles in the furnace. Industrialexperiments were also performed on a full-scale boiler. The gas temperature distribution along the primary airand coal mixture flow and in the furnace, and gas components such as O2, CO, CO2, and NOx in the near-wallregion, were measured with damper openings of the E-tier secondary air box at 0% and 30%. At 0%, ignitionof the primary air and pulverized coal mixture was delayed and the gas temperature peak was above theburner arch, with high NOx emission. Increasing the damper opening to 30% provided the oxygen necessaryfor the initial combustion. This was advantageous for stable combustion and also lowered NOx emissions andcarbon content in the fly ash.