摘要
为给二次再热锅炉设计优化及运行调温提供参考,该文通过数值计算对某660MW二次再热四角切圆塔式锅炉进行研究分析,采用用户自定义函数预测CO对NO_(x)的降低效果,研究烟气再循环对燃烧和传热特性的影响。结果表明,在炉膛上部受热面3种建模方式中,将其简化成平面是最优的。再循环烟气可提高煤粉颗粒的燃尽率。烟气再循环会缩小燃烧器高温区(1565~1700K)范围,提高过热器出口温度。当烟气再循环倍率从0%增加到20%,炉内氧浓度和冷灰斗区域的CO浓度均降低,低温过热器出口NO_(x)浓度从143.69降至94.07mg·m^(-3)(6%O_(2)),水冷壁吸热量占锅炉总吸热量比值降低3.50%,但再热器、过热器和省煤器分别增加2.53%、2.13%和0.54%。在炉膛中心线两侧热流密度分布呈近似对称的特点,主燃区热流密度达到330kW·m^(-2)。烟气再循环技术使水冷壁吸热能力降低,高热流密度区域缩小,提高了锅炉的安全性。
In order to provide reference for design optimization of double-reheat boiler and operating temperature regulation,the effects of flue gas recirculation on combustion and heat transfer characteristics are studied based on a 660 MW double-reheat tower-type boiler by numerical simulation.The user-defined function approach predicates the CO reduction effect on NO_(x).The numerical results show that it is optimal to simplify the convective heating surfaces into a plane among the three modeling methods for the upper heating surfaces in furnace.The recirculating flue gas could improve the burnout rate.The flue gas could shrink the high temperature area(1565~1700K)in burner area and improve the outlet temperature of low-temperature superheater.When the flue gas recirculation ratio increases to 20%,the oxygen concentration in the burner area and CO concentration at the hopper decrease.The NO_(x) emission at low temperature superheater outlet decreases from 143.69 to 94.07mg·m^(-3)(6%O_(2)).The ratio of heat absorption of water-cooled wall to total heat absorption decreases by 3.50%,but those ratios of reheater,superheater and economizer increase by 2.53%,2.13%and 0.54%,respectively.The heat flux is symmetrically distributed in the center line of the furnace.The peak of heat flux is about 330kW·m^(-2).Flue gas recirculation technology shrinks the high flux area and improves the safety of boiler operation.
作者
董凌霄
姚峤鹏
靳晓灵
邓磊
车得福
DONG Lingxiao;YAO Qiaopeng;JIN Xiaoling;DENG Lei;CHE Defu(State Key Laboratory of Multiphase Flow in Power Engineering(Xi’an Jiaotong University),Xi’an 710049,Shaanxi Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2023年第18期7150-7159,共10页
Proceedings of the CSEE
基金
国家重点研发计划项目(2017YFB0602102)。
关键词
二次再热
数值模拟
烟气再循环
燃烧传热特性
受热面建模方式
热流密度
double-reheat
numerical simulation
flue gas recirculation
combustion and heat transfer characteristics
modeling method on heating surface
heat flux
