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借助循环流化床试验台架研究了水蒸气和石灰石对煤流化床富氧燃烧时NO析出的影响.结果表明:与空气燃烧相比,煤在体积分数比φ(O2)∶φ(CO2)=21%∶79%气氛下燃烧时NO的析出量降低.O2+CO2气氛下,随着O2体积浓度的增加,NO的析出量逐渐增大.水蒸气加入后,燃烧温度降低,且受到水煤气反应和水的离解等化学作用的影响,NO还原反应增强,析出量降低;水蒸气体积浓度越高,析出量的降低越大.CO2体积浓度的增加对NO还原反应的影响要大于水蒸气体积浓度增加时.石灰石煅烧产物CaO对密相区NO还原反应的催化作用占主导地位,进而致使NO的析出量降低;且其对挥发份较高的黄陵烟煤的影响要小于对挥发份较低的晋城无烟煤的影响.水蒸气会加速CaO的烧结,降低CaO对NO还原反应的催化作用.
The effect of water vapor and limestone on the NO deposition during the oxyfuel combustion of coal fluidized bed was studied by means of a circulating fluidized bed test bed.The results show that the ratio of the volume fraction of coal to the NO (O2): φ (CO2 ) = 21%: The amount of NO precipitated was decreased when it was burned under 79% atmosphere.With the increase of O2 concentration, the amount of NO precipitated increased under the atmosphere of O2 + CO2.The temperature of combustion decreased after water vapor was added, Water gas reaction and dissociation of water and other chemical effects, NO reduction reaction enhanced precipitation decreased; the higher the volume concentration of water vapor, the greater the reduction of precipitation.CO2 volume concentration of NO reduction reaction is greater than the impact of water vapor When the volume concentration is increased, the catalytic effect of CaO calcined product of limestone on the NO reduction reaction in the dense phase is dominant, which leads to the decrease of the NO deposition amount. The effect on the Huangling bituminous coal with higher volatile content is smaller than that of the Huangling bituminous coal, Low Jincheng anthracite effect.Water vapor will accelerate the sintering of CaO, reduce the catalytic effect of CaO on the reduction of NO.