摘要
针对锅炉在超低负荷下运行时通常过量空气系数较高,导致NO_(x)浓度较高的问题,采用数值模拟的方法研究锅炉在低氧工况下不同给煤位置的燃烧特性和NO_(x)排放特性.结果表明:50%与30%汽轮机热耗率验收(THA)工况下采用相同磨煤机组合运行时,速度、烟气组分、温度分布规律类似,进粉位置上移导致主燃区上部温度升高且分布更均匀,切圆半径逐渐减小,燃尽风消旋作用使混合增强,因此有利于燃烧的稳定.2台磨煤机运行相比3台局部煤粉浓度更大,主燃区的燃烧温度更高,导致更多NO_(x)生成;30%THA工况下,当下层磨煤机运行时冷灰斗附近温度较高;低氧工况下,NO_(x)质量浓度最高值低于360mg/m^(3),当负荷从50%THA降低至30%THA,炉膛出口NO_(x)浓度降低20.8%.
When the boiler runs under ultra-low load,the excess air coefficient is high,which will lead to a high NO_(x) concentration.In this paper,numerical simulation is used to study the combustion characteristics and NO_(x) emission characteristics of different coal feeding locations under low-O_(2) conditions.The results indicate that at 50%and 30%THA conditions under the same mills operation,the velocity,flue gas species and temperature distribution are similar.The upper feeding locations results in a more uniform and higher distribution of temperature in the main combustion zone,and gradually reduce the imaginary circle radius,enhanced turbulence by counter-tangential air,thus it is advantageous to the combustion stability.During the two mills operation,the concentration of coal powder is larger than three mills,and the combustion temperature in the main combustion area is higher,resulting in more NO_(x) generation.At 30%THA conditions,the temperature near the ash hopper is higher when the lower mill is running.During low-O_(2) combustion conditions,the maximum NO_(x) concentration is less than 360 mg/m^(3).When the load is reduced from 50%THA to 30%THA,the NO_(x) concentration at the outlet of the furnace is reduced by 20.8%.
作者
马达夫
刘欢
何翔
关心
张守玉
泮浩翔
MA DAfu;LIU Huan;HE Xiang;GUAN Xin;ZHANG Shouyu;PAN Haoxiang(Shanghai Power Equipment Research Institute Co.,Ltd.,Shanghai 200240,China;School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 20093,China;Harbin Power System Engineering&Research Institute Co.,Ltd.,Harbin 150046,China)
出处
《锅炉技术》
北大核心
2024年第5期43-51,共9页
Boiler Technology
关键词
超低负荷
塔式炉
低氧工况
不同给粉位置
燃烧过程
ultra-low load
tower boiler
low-O_(2)condition
different coal feeding position
combustion process
