电站锅炉空气分级燃烧的数值模拟

阐述了电站锅炉采用空气分级燃烧降低NOx排放的原理及其技术关键。针对目前应用效果最好的组合空气分级燃烧技术,以一台600 MW超临界锅炉为例,应用数值模拟软件分别对采用一级分离燃尽风方式和两级燃尽风方式的组合空气分级燃烧进行了数值模拟,模拟结果与实测值基本吻合。结果表明,与一级分离燃尽风方式相比采用两级分离燃尽风方式时NOx的排放量更低,水冷壁表面的热流密度较均匀;同时两级分离使燃烧推迟,飞灰含碳量及屏底的烟温较高,通过合理调节燃尽风配比和燃烧器摆角可以避免锅炉效率下降和管壁超温。采用两级分离燃尽风的组合空气分级燃烧技术具有更好的应用前景。

Numerical Simulation of Air-Staged Combustion in Utility Boiler

The theory and technical key of reducing NOx emission with combined air-staged combustion,having a best applied effect,was described.A numerical simulation on the combustion process with technology of combined air-staged using one-stage separated over fire air and two-stage separated over fire air for a 600MW supercritical boiler was conducted by CFD software.The results indicate that the simulated value was consistent with the test data.Comparing with the combined air-staged combustion using one-stage SOFA,the NOx emission of that using two-stage SOFA is lower,the surface heat flux is more uniform,unburned carbon in fly ash and gas temperature of panel bottom is higher due to the delay of combustion.The depression of boiler efficiency and overheating when using two-stage SOFA can be avoided by regulating the ratio of SOFA and angle of burner.The technology of combined air-staged combustion using two-stage SOFA has a better application prospect.