Numerical Simulation Of Rich Oxygen Combustion Process In450MW Swirl-opposed Firing Boiler

Environmental pollution caused by coal-fired power plant isincreasingly endangering human beings healthy and survival environment. Theemission of the pollution mainly includes NO_X, SO₂and CO₂. Many domestic andforeign scholars have done a lot of research about a coal-fired boiler pollutant controlmethod. As a new type of combustion technology, Oxy-fuel combustion technologycan collect CO₂without separation, at the same time process SO₂and reduce NO_Xemissions, which is practically significant to the environment.Compared with four corners tangent circle, Opposed Firing Boiler（QFS） withswirl burner has unique advantages in anti-slagging corrosion, combustion stability inlow-load and deviating smoke temperature, which is also the future developmenttrend of large-scale power plant boiler. In order to reduce emissions of pollutants, thecharacteristics of QFS fired coal in oxygen-enriched combustion are researched bynumerical simulation though CFD software. Specific work and conclusions are asfollows:Cold state numerical simulation is calculated in a new single inside direct currentexternal cyclone flow burner. The results show that a20%increase in the diameter ofthe center recirculation zone and a50%increase in the length of the recirculation zonewhen swirling number changes from0.79to1.28; if swirling number is greater than1.28, the backflow zone has the trend of decrease.On the basis of the single vortex burner research, the combustion process in theburner of boiler furnace is calculated with detailed numerical simulation.Theconclusion is that the mutual influence of cyclone burner combustion is small.Airflow into the furnace form backflow zone, the fullness of flames in the furnace isbetter, smoke temperature distribution is reasonable, and it can guarantee pulverizedcoal ignition and combustion process are not affected by the influence of combustionorganization.Rich oxygen combustion technology is used in450MW cyclone coal fired boilerto study on ignition characteristics. Compared with the air atmosphere, furnacetemperature is much lower when the concentration of O₂is21%, and it is raised withthe O₂concentration increased; the pulverized coal combustion is strengthened andaccelerated; NO formation is greatly reduced, which is about1/4to1/2of the airatmosphere and risen with the increase of imports of flue gas O₂concentration; SO₂formation is significantly reduced, and risen with the increase of imports of flue gasO₂concentration.