660MW超超临界二次再热燃煤锅炉运行特性试验研究

Experimental study on operation characteristics of a 660 MW ultra-supercritical coal-fired boiler with double reheat cycle

针对某660 MW超超临界二次再热旋流燃烧锅炉投产后锅炉燃烧均衡性较差,锅炉热效率和一、二次再热汽温偏低,NO_(x)排放质量浓度偏高等问题,通过改变O_(2)体积分数、煤粉细度、一次风量、外二次风挡板开度、异层燃烧器风量分配方式、燃尽风直流风水平摆角和燃尽风量等参数对其进行了性能优化试验研究。结果表明:通过提高O_(2)体积分数运行和磨煤机动态分离器转速,以及合理设置外二次风配风方式、燃尽风直流风水平摆角及燃尽风风门开度,有效降低了灰、渣碳质量分数和CO排放浓度,提高了一、二次再热蒸汽温度。在各影响因素中,同层煤粉燃烧器外二次风风门开度和燃尽风直流风水平摆角的配置,对锅炉燃烧均衡性的影响至关重要;运行O_(2)体积分数和燃尽风量大小对NO_(x)排放影响最大。通过综合优化调整,锅炉性能得到明显改善,各项主要性能参数均达到或优于设计值。

Aiming at some issues of the 660 MW ultra-supercritical swirl combustion pulverized-coal boiler with double reheat cycle put into production in a power plant,such as poor combustion balance of boiler,low thermal efficiency of boiler and primary and secondary reheat steam temperature as well as high mass concentration of NO_(x)emission,the boiler performance optimization tests were carried out by varying the parameters of O_(2)volume fraction,pulverized coal fineness,primary air flow rate,the opening of external secondary air baffle,different layer burners′air distribution,horizontal swing angle of direct current(DC)air of overfire air(OFA)and OFA flow rate.The test results show that by increasing the operation O_(2)volume fraction and the rotating speed of the dynamic separator of the coal mill,and setting a reasonable external secondary air distribution mode,the horizontal swing angle of the DC air of OFA and the opening of OFA nozzle,the ash and slag carbon mass fraction and CO emission concentration can be effectively reduced,and the primary and secondary reheat steam temperatures can be increased.Among the various influence factors,the configurations of opening of external secondary air nozzle of pulverizedcoal burner on the same layer and the horizontal swing angle of the DC air of OFA have a significant impact on the combustion balance of the boiler;the operation O_(2)volume fraction and OFA flow rate are the most sensitive to NO_(x)emission.Through the comprehensive optimization and adjustment,the boiler performance is significantly improved,and its main performance parameters are achieved or superior to the design values.