Study On Low NOx Combustion System Transformation Of Coal-Fired Utility Boiler

As the execution of new environmental standards in China, the NOx emissions fromthermal power plants have become more prominent. The combustion control and de-NOx ofthe flue gas are the main technical to reduce the NOx emissions in coal fired power plants. Inthe thesis, it was paid more attention on introduction of the mechanism of NOx formation andthe development of de-NOx technology on the world. Meanwhile, the lower-nitrogencombustion technology and the flue gas de-NOx technology mainly on technologicalparameter and application were also introduced.Based on the convenience and economy of construction in filed, it is focused on the lowNOx combustion technology which is the important complementary of the flue gas de-NOxtechnology. A200MW coal-fired boiler was selected as the research object to comparativeanalysis of the different low-NOx combustion technologies. At last, the low NOx combustiontechnology based on staged combustion was employed. The modification of primarycombustion zone outlet, mill separator and separated overfire air vents were implemented.Based on the cold and hot tests, the influence of the modification on the boiler operation wasanalyzed.The analysis results show that50%NOx emission was reduced, while the unburnedcarbon in fly ash increased by1.5wt.%. In addition, the temperature deviation of both sidesof the flue gas was also reduced evidently. Generally speaking, the boiler efficiency wasincreased by nearly1%.