Studies On The Impact Of The Air Temperature On The Combustion Characteristics Of The0.5MW Central-fuel-rich Coal Combustion Burner

The majority of the existing burners of the national thermal power plants areabroad from other other countries’ low NOXemissions technolog. The burning coalof the national thermal power plants is poor and co-firing, making the burning rateis low, it is difficult to burn stably under the low load, the water wall slagging underhigh temperature and high NOXemissions. So it is important to develop the highefficiency and low NOXemissions burner which is appropriated the national coalproperties.The Central-fuel-rich Swirl Burner which integrates Air staged combustiontechnology and coal staged combustion technique can ensure the coal ignitionssmoothly and stable combustion, reducing the NOXemissions, and meanwhile theburning rate is relatively high. In this paper, building a Thermal test bench to studythe Pulverized coal combustion characteristics of the primary air and the second airunder the primary combustion zone, the OFA zone and the centerline of the Boiler.Keep the mass flow rate of the primary and secondary air constant, the changeof the temperature will cause variations of the density, thus the velocity of theprimary and secondary air will change, too. And this will has a strong impact on theaerodynamics of the outlet for the central-fuel-rich swirl coal combustion burner.The results indicated that the pulverized coal ignition early and the flamecenter position raise up, the temperature of the main combustion region is alsoincreased, while the temperature of the furnace flue gas decreased, the NOXof thefurnace tail reduced from460mg/m³@6%O₂to413mg/m³@6%O₂, when theprimary air temperature increased from100℃to200℃. When the primary airtemperature reached to300℃, the speed of the primary air would increase from11.2m/s to17.2m/s, the ignition delay compared with the case that when theprimary air temperature is100℃, and the temperature of the main combustionregion is also lower, while the temperature of the furnace flue gas is higher, and theNOXof the furnace tail increased to466mg/m³@6%O₂.The results showed that the pulverized coal ignition early, the CO content ofthe main combustion region increase rapidly, the flame center position raise up significantly, and the temperature of the furnace tail decreased from739℃to603℃, the NOXof the furnace tail reduced from459mg/m³@6%O₂to390mg/m³@6%O₂.