燃煤锅炉低NO_x燃烧技术节点功能区的应用

APPLICATION OF NODE FUNCTION ZONE IN LOW NO_x BURNER TECHNOLOGY FOR COAL-FIRED BOILERS

在燃煤锅炉燃烧系统主燃区引入节点功能区的概念,运用浓淡煤粉燃烧器和贴壁风技术,将相邻2层一次风喷口中的下层设计为上浓下淡煤粉喷口,将上层设计为下浓上淡煤粉喷口,设置2层一次风喷口之间的二次风与一次风小角度偏置,同时在中间二次风两侧布置贴壁风,利用CFD数值模拟软件计算煤粉燃烧过程中节点功能区的速度场、温度场及O2和CO浓度场分布,使燃烧系统实现了稳燃、低NOx排放、防结焦及防高温腐蚀等多重功能。应用结果表明,运用节点功能区的低NOx燃烧系统中,NOx排放浓度减少50%～70%,飞灰可燃物含量无明显升高,结焦现象得到改善。

The concept of node function zone has been introduced into main combustion zone of the com- bustion system for coal - fired boilers. By using technologies of thick - and - thin pulverized coal burn- ers as well as the wall - sticking air, the primary air injecting nozzles of two neighbouring levels have been designed,the injecting nozzles in lower level are thick burner at upper part and thin burner at lower part,whereas the injecting nozzles in upper level are thin burner at upper＇part and thick burner at lower part;the secondary air between two levels of primary air injecting nozzles is biased with pri- mary air at a small angle,at the same time,the wall -sticking air is arranged at two sides of the central secondary air. By using the CFD numerical simulation software,the distribution of velocity field,tem- perature field, as well as O2 and CO concentration field over node function zone in the combustion process of pulverized coal has been calculated , and many functions , such as ignition and combustion stabilization,low emission of NOx ,prevention of slagging and high- temperature corrosion etc. , being arranged to air compartments for pulverized coal and air. Results of application show that the utiliza- tion of low NOx combustion system in node function zone can make the concentration of NO, emission to be effectively reduced, at the same time, the combustible content in fly ash hasn＇t substantially in- creased,and the slagging phenomenon being remarkablly improved.