摘要
为解决某电厂超临界660 MW循环流化床(circulating fluidized bed,CFB)锅炉满负荷运行NO_(x)排放较难控制、瞬时值易超过超低排放限值且选择性非催化还原(selective non-catalytic reduction,SNCR)脱硝系统氨耗量较大氨逃逸严重的问题,现场进行了NO_(x)原始排放、SNCR脱硝效率、CO质量浓度及底渣可燃物的试验,并进行了二次风量布置优化试验。研究发现:锅炉原始NO_(x)排放较低,满负荷运行时不超过120 mg/m^(3)(标准状态,下同);中低负荷时NO_(x)质量浓度低于50 mg/m^(3),但炉膛前后NO_(x)质量浓度偏差较大,烟气中的NO_(x)主要在炉膛前部产生。NO_(x)排放较难控制的原因是SNCR脱硝效率较低和炉膛给煤不均。6台分离器入口的SNCR脱硝效率均低于50.0%,其中B、C、E、F 4台分离器脱硝效率低于40.0%。此外,从原始NO_(x)生成来看,根据炉膛深度方向上床温分布、底渣可燃物质量分数和CO质量浓度变化可以确定,炉膛给煤不均也对满负荷NO_(x)排放控制影响显著。当前,电厂若不进行给煤系统改造暂无法实现给煤均匀,但可以通过调整炉膛深度方向二次风量配比降低原始NO_(x)生成,降幅可达9.77%。
It is difficult to control NO_(x)emissions during full load operation of a 660 MW supercritical circulating fluidized bed(CFB)boiler in a certain power plant,and its instantaneous value is prone to exceed the ultra-low emission limit.In addition,the selective non-catalytic reduction(SNCR)system has a high ammonia consumption and severe ammonia escape issues.To solve these problems,on-site experiments on NO_(x)original emissions,SNCR denitrification efficiency,CO mass concentration and bottom slag combustibles were conducted,and optimization experiments on secondary air volume layout were also performed.It was found that,the original NO_(x)emissions of the CFB boiler were relatively low,with a maximum of 120 mg/m^(3)(standard condition)during full load operation and a NO_(x)mass concentration below 50 mg/m^(3)during medium and low loads.However,there was a significant deviation in NO_(x)mass concentration between the front and rear ends of the furnace,and the NO_(x)in flue gas was mainly generated in front of the furnace.The reason why NO_(x)emissions are difficult to control is due to the low denitrification efficiency of SNCR and uneven coal feeding in the furnace.The SNCR denitrification efficiency at inlet of the 6 separators was all below 50%,among which the denitrification efficiency of four separators B,C,E,and F was below 40%.Furthermore,according to the distribution of parameters in the furnace depth direction,such as the bed temperature,the content of combustible materials in bottom slag,and the variation of CO mass concentration,it can be determined that the uniformity of coal feeding in the furnace also had a significant effect on the control of NO_(x)emissions at full load.Currently,the power plant cannot achieve uniform coal feeding without renovation,but the original NO_(x)generation can be reduced by adjusting the secondary air volume ratio in the depth direction of the furnace,with a reduction of up to 9.77%.
作者
张文祥
晏海能
孙志军
雷雨
薛宁
武晓峰
ZHANG Wenxiang;YAN Haineng;SUN Zhijun;LEI Yu;XUE Ning;WU Xiaofeng(SujinShuozhou Gangue Power Generation Co.,Ltd.,Shuozhou 036800,China;Xi’an Thermal Power Research Institute Co.,Ltd.,Xi’an 710054,China)
出处
《热力发电》
CAS
CSCD
北大核心
2024年第5期109-114,共6页
Thermal Power Generation
