磨煤机启停导致氮氧化物波动控制技术研究  

Research on Control Technology of Nitrogen Oxide Fluctuation Caused by Starting and Stopping Coal Mill

作　　者：宋益纯 SONG Yichun(State Energy Group Shandong Electric Power Co.,Ltd.,Jinan 250101,China)

机构地区：[1]国家能源集团山东电力有限公司,山东济南250101

出　　处：《山东电力技术》2021年第8期70-76,共7页Shandong Electric Power

基　　金：国家能源集团山东电力有限公司2020年科技项目“降低双进双出磨煤机启停对脱硝系统强扰动控制技术研究”(202004)。

摘　　要：磨煤机启停容易导致锅炉出口氮氧化物浓度大幅波动,影响脱硝系统的稳定运行。以双进双出钢球磨煤机为例,研究启停磨时氮氧化物波动与容量风、煤位、停磨吹扫时间、二次风量等参数变化的对应关系,确认停磨吹扫时间短、磨内有存煤且入炉煤量与二次风量不匹配,是造成停磨时氮氧化物浓度大幅波动的主因;磨内存煤未吹净、下次启磨时较多煤粉进入炉膛燃烧是造成启磨期间氮氧化物浓度大幅波动的主因。设计磨煤机停磨期间吹扫控制逻辑,确保存煤吹净;修改启停磨期间容量风量折算为燃料量的控制算法,将容量风量按磨煤机内存煤吹扫情况进行修正后折算为燃料量,使折算后的燃料量尽可能接近真实的煤粉量。经实验证实,合理控制停磨前吹扫时间,将磨内存煤吹净及全程投入二次风量自动能明显降低氮氧化物波动幅度,磨煤机启停对脱硝系统的强烈扰动得到有效控制。The start⁃up and shutdown of coal mill will easily lead to large fluctuation of NO_(x) at boiler outlet,which will affect the stable operation of denitration system.Taking the double inlet and double outlet ball coal mill as an example,the corresponding relationship between the fluctuation of nitrogen oxides and the changes of capacity air,coal level,blowing time,secondary air volume and other parameters during the start⁃up and shutdown of the mill is studied.It is confirmed that the short blowing time,coal storage in the mill and the mismatch between the quantity of coal into the furnace and the secondary air volume are the main reasons for the large fluctuation of NO_(x) during the shutdown period;The coal in the mill is not blown clean and the next start⁃up of the mill more pulverized coal into the furnace combustion are the main reasons for the large fluctuation of NO_(x) during the start⁃up period.Design the purge control logic of the coal mill during the shutdown period to ensure the coal purge;Modify the control algorithm of converting the capacity air volume into the fuel volume during the startup and shutdown period,and convert the capacity air volume into the fuel volume according to the coal purge condition in the mill,so as to make the converted fuel volume as close as possible to the real pulverized coal volume.The experimental results show that reasonable control of the blowing time before shutdown the mill,purging the coal in the mill and automatically putting the secondary air volume into operation in the whole process can significantly reduce the fluctuation range of NO_(x),and the strong disturbance of the denitration system caused by the start⁃up and shutdown of the mill can be effectively controlled.

关 键 词：磨煤机 脱硝 扰动 优化控制 启停 吹扫 氮氧化物 

分 类 号：TK262[动力工程及工程热物理—动力机械及工程]