低氮改造后四角切圆燃煤粉锅炉变负荷下NO_x生成规律数值模拟研究

Study of the Numerical Simulation of the Law of NO_x Formation in a Tangential Pulverized-coal-fired Boiler at a Variable Load After a Low Nitrogen Modification

利用ANSYS FLUENT 14.0软件进行了沙角C电厂低氮改造后不同负荷下燃烧特性的数值模拟,主要研究了炉膛速度场、温度场、组分场和污染物分布的规律,结果表明:低氮改造后增加SOFA(分离燃烬风)风使炉膛温度分布较均匀,切圆形成比较好,没有出现火焰贴墙现象;从40%负荷到100%负荷,燃烧器区域温度相差132.9 K,降低幅度达到了7.8%;随着负荷降低,炉膛出口烟气温度逐渐降低;随着负荷降低,炉膛出口NOx浓度逐渐降低。

By making use of the software Ansys Fluent 14. 0,the authors conducted a numerical simulation of the combustion characteristics at a variable load after a low nitrogen modification to a power plant with the law governing the speed field,temperature field and constituent field in the furnace as well as the distribution of pollutants being mainly studied. It has been found that after the low nitrogen modification,to increase the amount of SOFA air can make the temperature distribution in the furnace to be comparatively uniform,the formation of the tangential circles is relatively good and there emerge no flame-closing-to-wall phenomena; the temperature difference in the zone of the burners between the load of 40% and 100% is 132. 9 K and the descending range is up to 7. 8%; with a decrease of the load,the temperature of flue gases at the outlet of the furnace will gradually decline; with a drop of the load,the NOxconcentration at the outlet of the furnace will gradually become lower.