低负荷下循环流化床全炉膛脱硝数值模拟研究OA
Numerical simulation of full-furnace denitration in a circulating fluidized bed under low-load conditions
[目的]循环流化床在低负荷运行时,存在炉内选择性非催化还原脱硝效率不高的问题.为了解决该问题,需要研究循环流化床在特定低负荷时的喷氨和脱硝规律.[方法]本文采用计算流体力学(computational fluid dynamics,CFD)数值模拟,在40％锅炉最大连续蒸发量工况下,对350 MW超临界循环流化床锅炉开展炉内脱硝研究.主要研究内容包括3部分,首先通过对比分析从给煤口、上/下二次风口(前沿)、返料口等处安装喷枪喷入氨气对脱硝效率的影响,从而确定最佳喷氨位置;然后研究氨氮摩尔比对脱硝效率和氨逃逸的影响;最后分析氨喷射速度对脱硝的影响.[结果]研究表明:(1)给煤口是最佳的氨气喷入位置,其脱硝效率较上二次风口、下二次风口、返料口分别高4.4％、2.4％、12.9％;(2)氨氮摩尔比从1.0提升到1.5时,脱硝效率提升了 13个百分点,此时脱硝效率为58.5％,氨逃逸量为7.6 mg/m3.当氨氮摩尔比进一步提高时,脱硝效率的提升趋于稳定,且氨逃逸浓度超标.(3)脱硝效率随着氨喷射速度增大而提高,当喷射速度提高到80 m/s时,NOx浓度下降到45.8 mg/m3,脱硝效果达到最佳.[结论]本研究通过对350 MW超临界循环流化床锅炉低负荷下全炉膛脱硝进行数值模拟研究,得到了最佳喷入位置、氨氮摩尔比以及喷射速度,为循环流化床锅炉在低负荷条件下实现高效、稳定脱硝提供了新思路与理论支撑.
[Objective]At low load,the circulating fluidized bed has the problem of low denitration efficiency in the furnace.In order to solve this problem,it is necessary to study the law of ammonia injection and denitrification in circulating fluidized bed at a specific low load.[Methods]Computational Fluid Dynamics(CFD)numerical simulation was employed to investigate the effectiveness and feasibility of in-furnace denitration within a 350 MW supercritical CFB boiler.The research primarily consisted of three parts:firstly,comparing and analyzing the impact of ammonia injection via nozzles installed at different locations-the coal feed port,upper/lower secondary air ports(front wall),and return material port on denitration efficiency to determine the optimal injection location;secondly,studying the influence of the ammonia-to-nitrogen molar ratio(NSR)on both denitration efficiency and ammonia slip;finally,analyzing the effect of the injection velocity on denitration performance.[Results]The results show that:(1)The coal feeding port is the best ammonia injection position,and its denitration efficiency is 4.4％,2.4％and 12.9％higher than that of the upper secondary air outlet,the lower secondary air outlet and the return port,respectively.(2)When the molar ratio of ammonia to nitrogen increased from 1.0 to 1.5,the denitrification efficiency increased by 13 percentage points.At this time,the denitrification efficiency was 58.5％,and the ammonia escape was 7.6 mg/m3.When the molar ratio of ammonia nitrogen is further improved,the improvement of denitrification efficiency tends to be stable,and the ammonia escape concentration exceeds the standard.(3)The denitrification efficiency increases with the increase of ammonia injection speed.When the injection speed increases to 80 m/s,the NOx concentration decreases to 45.8 mg/m3,and the denitrification effect is the best.[Conclusion]Through full-furnace CFD simulation of the 350 MW supercritical CFB boiler under low-load conditions,this study identified the optimal ammonia injection location,NSR,and injection velocity.It provides a new approach and theoretical foundation for achieving efficient and stable denitration in CFB boilers operating under low-load conditions.
梅佳伟;闫高程
山西大学电力与建筑学院,山西太原 030006山西大学电力与建筑学院,山西太原 030006
能源科技
循环流化床锅炉数值模拟炉内脱硝氨氮摩尔比脱硝优化
circulating fluidized bed boilernumerical simulationin-furnace denitrificationNH3/NOx molar ratiodenitrification optimization
《电力科技与环保》 2026 (2)
223-233,11
山西省基础研究计划资助项目(202403021212327)
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