CFB锅炉循环灰对NO和N_2O排放影响的实验研究

Experimental investigation of the effects of circulating ash from CFB boilers on NO and N_2O emissions

在循环流化床(CFB)锅炉中,NOx和N2O的排放浓度由NOx和N2O在炉膛内生成和降解的相对速度决定。该文利用小型流化床实验台研究了循环灰对NO和N2O浓度的影响。实验温度控制在850℃,反应时间为25ms。结果表明:在实验台反应器中加入一定量的循环灰以后,NO的排放浓度降低,而N2O的排放浓度先增加然后略有降低;循环灰中的C以及C反应生成的CO能还原NO,并促进N2O的生成,而循环灰中的CaO、Fe2O3等活性组分能促进N2O的热分解。

The NOx and N2O emissions from a circulating fluidized bed （CFB） boiler are predicted based on their formation and destruction rates in the furnace. The effects of the circulating ash in the CFB boiler on the NO and N2O emissions were investigated using a laboratory-scale fluidized bed reactor with a reactor temperature of 850℃ and a residence time of 25 ms. The results show that the added ash reduces the NO concentration, while increasing the N2O concentration at first and then slightly decreasing the N2O concentration minutes later. The residue char in the circulating materials and CO generated from the char play important roles in the NO reduction and N2O formation; however, the active components of the circulating ash, such as CaO and Fe2O3, accelerate the N2O thermal decomposition.