By eddy-dissipation (ED) model, the mixed combustion characteristics of a 600 MW unit coal-fired boiler which co-burning ventilation air methane (VAM) was numerically studied. The influence of the VAM's volume fraction on combustion characteristics and NOx generation characteristics were researched. The results show that, with an in increase in the VAM's volume fraction, the average temperature of main burner region decreases by 30 K at most, however, the scope of decrease is not obvious. Meanwhile, the average temperature above the main burner region increases at first and then decreases. With an increase in volume fraction of methane, the oxygen concentration in furnace cross-section decreases and the production of CO rises. After the VAM is added, with an increase in the methane's volume fraction, the NOx mass concentration around the burner area of C/D/E/F layer increases , while that around the burner area of A/B layer reduces, by 253.21 mg/m3at most. When the VAM with methane's volume fraction of 1.5％ is added into the furnace, the NOx concentration at the furnace outlet decreases from 569.64 mg/m3to 519.24 mg/m3, by 8.85％. The numerical simulation indicates that adding VAM into the furnace not only contributes to saving resources and protecting the environment, but also helps reducing the emission of NOx.%使用涡耗散模型,对某600 MW机组锅炉掺烧矿井乏风后的燃烧特性进行了数值模拟,研究了乏风体积分数对锅炉燃烧特性及NOx生成特性的影响.结果表明:随着乏风体积分数的上升,主燃烧器区域内炉膛平均温度降低幅度最高为30 K,降低幅度并不明显,主燃烧器区域上层平均温度先上升后降低;在整体上炉膛截面氧体积分数随着甲烷体积分数的上升而降低,一氧化碳体积分数随着甲烷体积分数升高而升高;掺烧矿井乏风后,CDEF层燃烧器区域内NOx质量浓度随着甲烷体积分数上升而上升,AB层燃烧器区域上层炉膛截面NOx质量浓度随着甲烷体积分数上升而降低,降低幅度最多为253.21 mg/m3;掺烧甲烷体积分数为1.5％的矿井乏风后,炉膛出口处NOx质量浓度从569.64 mg/m3降至519.24 mg/m3,降低幅度为8.85％.说明锅炉掺烧矿井乏风不仅能够节约资源和保护环境,还有助于降低NOx的排放.
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