Engineering Research Center of Ministry of Education for Resource Efficiency Enhancing and Carbon Emission Reduction in Yellow River Basin,National Key Laboratory for Efficient Resource Utilization Technologies of Coal Waste,Institute of Resources and Environmental Engineering,ShanxiUniversity
Shanxi Pingshuo Gangue Power Generation Limited Liability Company,Shuozhou

“双碳”背景下,随着新能源装机容量的持续增加,火电机组逐步从主体性电源向辅助服务型电源转变,由于新能源具有间歇性特点,火电机组需频繁进行变负荷以深度调峰的形式维持电网稳定。为解决深度调峰过程中低负荷下的NOx排放控制这一行业共性难题,以某超临界350MW循环流化床锅炉为研究对象,分析深度调峰条件下锅炉机组运行数据,综合床温、煤种特性、固硫剂添加等多方面因素对NOx质量浓度的影响,探究变负荷及中低负荷工况下NOx排放特性及影响机制。研究发现床温的变化与负荷呈正相关,温度降低时挥发分氮的氧化作用明显削弱,减少了NOx的生成;但随着锅炉负荷连续降低,为保持流化状态,密相区过量空气系数增加,导致NOx质量浓度相对中高负荷时更高;同时燃用硫分更高的煤种时,炉内脱硫所需的石灰石量增加,对NOx的催生作用越明显。为控制NOx超低排放,采用分区低氮燃烧技术和上二次风SNCR脱硝技术来进行调节。分区低氮燃烧精细化合理化控制给煤量、布风量分布,合理匹配燃料与空气量使得NOx得到精细化控制;而上二次风SNCR改造技术则在更合适位置喷入还原剂,使得脱硝反应处在较合理的温度区间内,从而提高脱硝效率。结果表明这2种技术可以有效控制低负荷工况下的NOx排放,为火力发电机组在新能源频繁波动的背景下保持稳定运行提供了可行的技术路径,对实现更低的排放水平、保障电网稳定运行具有重要意义。

Under the background of “dual carbon”,with the continuous increase of new energy installed capacity,thermal power unitsare gradually transforming from primary power sources to auxiliary service power sources. Due to the intermittent nature of new energy,thermal power units need to frequently change loads to maintain grid stability in the form of deep peak shaving. In order to solve thecommon problem of NOx emission control under low load during deep peak shaving,this paper takes a certain supercritical 350 MWcirculating fluidized bed boiler as the research object,analyzes the operating data of the boiler unit under deep peak shaving conditions,and comprehensively investigates the influence of various factors such as bed temperature,coal type characteristics,and sulfur fixing agent addition on NOx mass concentration,and explores the NOx emission characteristics and influencing mechanisms under variable load andlow load conditions. Research has found that changes in bed temperature are positively correlated with load,and the oxidation of volatilenitrogen is significantly weakened when the temperature decreases,reducing the generation of NOx; but as the boiler load continues todecrease,in order to maintain the fluidized state,the excess air coefficient in the dense phase zone increases,resulting in a relatively higherNOx concentration compared to medium to high loads; when using coal with higher sulfur content simultaneously,the amount oflimestone required for desulfurization in the furnace increases,and the effect of promoting NOx becomes more significant. To controlultra-low NOx emissions,zone based low nitrogen combustion technology and upper secondary air SNCR denitrification technology areused for regulation. Refine and rationalize the control of coal feeding and air distribution in low nitrogen combustion zones,and match thefuel and air quantities reasonably to achieve precise control of NOx; the secondary air SNCR retrofit technology sprays reducing agents atmore suitable locations to keep the denitrification reaction within a reasonable temperature range,thereby improving denitrificationefficiency. The results indicate that these two technologies can effectively control NOx emissions under low load conditions,providing afeasible technical path for thermal power generation units to maintain stable operation in the context of frequent fluctuations in newenergy. This is of great significance for achieving lower emission levels and ensuring stable operation of the power grid. The study confirmsthat employing zoned low-NOx combustion strategies or denitrification techniques such as secondary air SNCR can effectively reduce NOxemissions during low-load operations,thereby addressing this environmental challenge in the power generation industry.

国家重点研发计划资助项目(2020YFB0606203);国家自然科学基金联合基金项目(U21A20321);国家自然科学基金青年基金资助项目(22108162)

杨敬池,王菁,王鹏程,等.超临界350MW循环流化床锅炉宽负荷NOx排放特性及控制技术[J].洁净煤技术,2025,31(1):61−68.

YANG Jingchi,WANG Jing,WANG Pengcheng,et al. Characterization and mitigation of NOx emissions across a wideload range in supercritical 350 MW circulating fluidized bed boiler[J].Clean Coal Technology,2025,31(1):61−68.