Influence of the overfire air ratio on the NO(x) emission and combustion characteristics of a down-fired 300-MW(e) utility boiler.
Influence of the overfire air ratio on the NO(x) emission and combustion characteristics of a down-fired 300-MW(e) utility boiler.
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DOI：
10.1021/es100956d
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发表时间：
2010-08
影响因子：
11.4
通讯作者：
Feng Ren;Zhengqi Li;Zhichao Chen;Subo Fan;Guangkui Liu
中科院分区：
文献类型：
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作者：
Feng Ren;Zhengqi Li;Zhichao Chen;Subo Fan;Guangkui Liu
用于燃烧低挥发分煤的下燃式锅炉具有较高的 NO(x) 排放量。为了找到解决此问题的方法，在 300 MW(e) 下燃式锅炉上引入了过燃空气 (OFA) 系统。对该改造后的锅炉进行了足尺实验，探讨OFA比（OFA与总燃烧空气的质量流量比）对炉内燃烧和NO（x）排放特性的影响。测量了沿一次空气和煤混合物流的气体温度分布、沿炉高的平均气体温度、近壁区域的 O(2)、CO 和 NO(x) 等气体浓度以及飞灰中的碳含量。比较了五种不同 OFA 比率的数据。结果表明，随着OFA比例从12%增加到35%，NO(x)排放量从1308mg/Nm(3)减少到966mg/Nm(3)(在6%O(2)干度下)，飞灰中的碳含量从6.53%增加到15.86%。综合考虑环境和经济影响，选择25%作为优化的OFA比例。
Down-fired boilers used to burn low-volatile coals have high NO(x) emissions. To find a way of solving this problem, an overfire air (OFA) system was introduced on a 300 MW(e) down-fired boiler. Full-scale experiments were performed on this retrofitted boiler to explore the influence of the OFA ratio (the mass flux ratio of OFA to the total combustion air) on the combustion and NO(x) emission characteristics in the furnace. Measurements were taken of gas temperature distributions along the primary air and coal mixture flows, average gas temperatures along the furnace height, concentrations of gases such as O(2), CO, and NO(x) in the near-wall region and carbon content in the fly ash. Data were compared for five different OFA ratios. The results show that as the OFA ratio increases from 12% to 35%, the NO(x) emission decreases from 1308 to 966 mg/Nm(3) (at 6% O(2) dry) and the carbon content in the fly ash increases from 6.53% to 15.86%. Considering both the environmental and economic effect, 25% was chosen as the optimized OFA ratio.