Numerical simulation study on denitrification characteristics of CFB boiler separator
To investigate the denitrification characteristics of a cyclone separator in a circulating fluidized bed boiler,a 300 MW circulating fluidized bed boiler is chosen as the subject of this study.The impact of various key parameters on denitration efficiency,including the number and arrangement of urea spray devices,urea particle size,NH3/NO mole ratios,and boiler load.The numerical results suggested that the quantity and arrangement of urea spray devices significantly influence the mixing uniformity of ammonia nitrogen vertically.The best performance was achieved when there are 14 spray guns evenly distributed on both sides.Meanwhile,the particle size of the urea solution primarily affected the mixing horizontally,with the best mixing effect observed at a particle size of 80 μm.There existed an optimal range for NH3/NO mole ratios,beyond which denitration efficiency decreases.The optimal nitrogen molar ratio under full load operating conditions was 1.2.Denitrification efficiency decreases continuously as the boiler load decreased.This leaded to a situation where,when the boiler load fell below 40%,removing NOx solely in the cyclone separator was insufficient to meet the requirement of ultra-low emissions due to low flue gas temperatures in the cyclone separator.The findings of this study provided valuable insights for the design and operation of the denitration system of CFB boiler separators.
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