摘要
为探究掺混方式及配风方式对混煤燃尽率和NOx排放量的影响,以一台660MW四角切圆锅炉为研究对象,开展混煤燃烧过程未燃尽碳和NOx排放的协同优化数值研究。结果表明,在深度空气分级条件下,未燃尽碳主要受停留时间、掺混方式、配风方式等因素共同影响;合理搭配掺混方式和配风方案可降低混煤未燃尽碳水平和炉内NOx总生成量,达到两者的协同优化。与炉外掺混相比,炉内掺混更加灵活,可通过优化低挥发分煤的燃尽程度来改善混煤整体的未燃尽碳水平。在炉内掺混方式下,均等配风将低挥发分煤置于上部燃烧器或正宝塔配风将低挥发分煤置于下部燃烧器,均有利于低挥发分煤的燃尽;而将高挥发分煤置于上部燃烧器更有利于NOx减排。综合考虑混煤未燃尽碳和NOx排放特性,将高挥发分煤置于上部燃烧器且采用正宝塔配风可为下部低挥发分煤的燃烧提供相对充足的氧量,提高低挥发粉煤的燃尽率,降低混煤未燃尽碳水平;上部高挥发分煤析出的挥发分中含有大量含氮中间产物HCN,可将已生成的NOx还原,有利于降低炉内混煤NOx生成量。
In order to explore the influence of mixing mode and air distribution mode on burnout rate and NOx emission of blended coal,a 660 MW tangential fired boiler was taken as the research object,numerical simulations were carried out to study the synergistic optimization of un-burned carbon and NOx formation in the combustion process of blended coal.The results show that under the condition of deep air staging,the un-burned carbon is mainly affected by many factors such as coal particle residence time,coal blending methodand air distribution method and other factors.Synergistic optimization of un-burned carbon and NOx emissions can be achieved by a combination of reasonable blending method and air distribution method.Compared with the blending method outside the furnace,the in-furnace blending method is more flexible,and the low-volatile coal combustion can be optimized and adjusted to lower the un-burned carbon level of blended coal.Under the in-furnace blending method,the low volatile coal is placed near the upper burner under uniform air distribution or the low volatile coal is placed in the lower burner near the lower burner under “Zhengbaota” air distribution,which are both conducive to the burnout of low volatile coal,while setting high-volatile coal near the upper burner is more conducive to the reduction of NOx emission.Considering the characteristics of the unburned carbon and NOx emission of blended coal,the burnout level of the low-volatile coal is increased and the un-burned carbon level of blended coal is decreased by setting high-volatile coal near the upper burner and adopting the "Zhengbaota" air distribution which can provide relatively sufficient oxygen for the combustion of low volatile coal in the lower part.Meanwhile,the volatile from the high-volatile coal near the upper burner contains a large amount of intermediate HCN,which can restore the generated NOx and is benefit to reduce NOx formation of blended coal in the furnace.
作者
颜祝明
马仑
叶骥
张成
谭鹏
方庆艳
陈刚
YAN Zhuming;MA Lun;YE Ji;ZHANG Cheng;TAN Peng;FANG Qingyan;CHEN Gang(Guangdong Red Bay Power Generation Co.,Ltd.,Shanwei 516623,China;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology,Wuhan 430074,China)
出处
《洁净煤技术》
CAS
2019年第3期82-87,共6页
Clean Coal Technology
基金
国家自然科学基金资助项目(51676076)
关键词
深度空气分级
混煤燃烧
未燃尽碳
NOx
协同优化
deep air staging
blend-coal combustion
unburned carbon
NOx
synergistic optimization
