论文部分内容阅读
利用Ansys Fluent 14.0软件对某电厂660 MW四角切圆锅炉低氮改造后变磨煤机组合方式下的燃烧特性进行了数值模拟,研究了炉内的速度场、温度场、组分场和污染物的分布,并将数值模拟结果与试验测量值进行了比较.结果表明:增加分离燃尽风(SOFA)后的温度分布较均匀,切圆形成较好,没有出现火焰贴墙现象;在燃烧器区域,不同磨煤机组合方式下,温度沿炉膛高度方向逐渐升高;在紧凑燃尽风(CCOFA)与SOFA喷嘴之间的区域,炉膛横截面平均温度沿炉膛高度方向先降低、再升高、最后降低;在SOFA喷嘴以上的区域,不同磨煤机组合方式下的炉膛横截面平均温度曲线基本重合,且沿炉膛高度方向逐渐降低;在CCOFA与SOFA喷嘴之间的区域,不同磨煤机组合方式下,NOx质量浓度沿炉膛高度方向逐渐降低,而在SOFA喷嘴以上的区域NOx质量浓度先升高后降低,但其变化幅度较缓慢;当磨煤机组合方式为ABCEF时,炉膛出口NOx平均质量浓度最高,为382.2mg/m3;当磨煤机组合方式为ABCDE时,炉膛出口NOx平均质量浓度最低,为307.4mg/m3.
The combustion characteristics of 660 MW tangentially fired boiler in a power plant after low nitrogen retrofit combined with coal pulverizer were numerically simulated by Ansys Fluent 14.0 software. The velocity field, temperature field, component field and pollutants in the furnace were studied. The results show that the temperature distribution of SOFA is more uniform, the tangent circle is better and there is no phenomenon of flame sticking to the wall. In the burner In the region between the CCOFA and the SOFA nozzles, the average cross-sectional temperature of the furnace decreases first and then increases along the height of the hearth, , And finally decreased; in the area above the SOFA nozzle, the average temperature curve of the cross section of the furnace under different combinations of coal mills basically coincided and gradually decreased along the height of the furnace; in the area between the CCOFA and the SOFA nozzles, Under the combination mode, the NOx concentration gradually decreases along the height of the furnace, while the NOx concentration increases first and then decreases, but the variation range is relatively slow in the area above the SOFA nozzle. When the coal mill combination Is ABCEF, furnace outlet NOx mass average highest concentration of 382.2mg / m3; when the mill is a combination ABCDE, furnace outlet NOx mass average minimum concentration of 307.4mg / m3.