600MW对冲燃烧锅炉NO_x排放特性的数值模拟

Numerical Study on NO_x Emission Characteristics of a 600 MW Opposed Firing Boiler

采用数值模拟方法对某台600 MW超临界对冲燃烧锅炉不同燃尽风(OFA)风量比例和燃烧器运行组合方式时的NOx排放特性进行了研究.结果表明:在600 MW额定负荷时,随着OFA风量比例的增大,飞灰含碳量近似呈线性增加,但NO排放质量浓度明显下降;当OFA风量比例从25%增大至35%时,飞灰含碳量增加了1.22%,NO排放质量浓度下降了293mg/m3,当OFA风量比例接近30%时,飞灰含碳量和NO排放质量浓度综合指标最佳;停运上层燃烧器(运行组合方式为ACDEF)时,飞灰含碳量和NO排放质量浓度相较于停运中层燃烧器(运行组合方式为ABCDE)和下层燃烧器(运行组合方式为BCDEF)时有所下降;与停运下层燃烧器相比,停运上层燃烧器时飞灰含碳量降低了0.46%,NO排放质量浓度降低了40mg/m3.

NOxemission characteristics of a 600 MW ultra supercritical opposed firing boiler were numerically simulated under different ratios of over fire air(OFA)at different modes of in-service burner layers.Results show that at the rated load of 600 MW,the carbon content in fly ash linearly increases but the NO emission significantly reduces with the rise of OFA ratio;when the OFA ratio increases from 25% to35%,the carbon content in fly ash will be raised by 1.22%,and the NO emission will be reduced by 293mg/m3,and the optimal comprehensive index can be obtained at the OFA ratio of 30%.Both the fly ash carbon content and the NO emission produced in the ACDEF burner operation mode are lower than those in the ABCDE and BCDEF mode;compared with the BCDEF mode,the fly ash carbon content and the NO emission in ACDEF mode are respectively reduced by 0.46% and 40mg/m3.