粉煤循环流化床燃烧技术  

Powdered coal circulating fluidized bed combustion technology

作　　者：吕俊复[1] 尚曼霞 柯希玮 周托 黄中 张海[1] 张缦[1] 张扬[1] 吴玉新[1] 岳光溪[1] Lü Junfu;SHANG Manxia;KE Xiwei;ZHOU Tuo;HUANG Zhong;ZHANG Hai;ZHANG Man;ZHANG Yang;WU Yuxin;YUE Guangxi(Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Tsinghua Unwersity,Beying 100084,China)

机构地区：[1]清华大学热科学与动力工程教育部重点实验室,北京100084

出　　处：《煤炭学报》2023年第1期430-437,共8页Journal of China Coal Society

基　　金：中国工程院咨询资助项目(2020-XY-10);华能集团总部科技项目“基础能源科技研究专项”(二)资助项目(HNKJ21-H31)。

摘　　要：双碳背景下,作为燃煤发电的重要组成部分,循环流化床(CFB)燃烧技术实现了劣质燃料的高效清洁利用,也是未来参与电网深度调峰的主力。然而,CFB锅炉在负荷调节速率、深度低负荷及低负荷下的NOx排放控制、受热面磨损等方面还有较大改善空间。为此,提出了粉煤循环流化床(Powdered Coal-Circulating Fluidized Bed,PC-CFB)燃烧技术,将燃料粒度由传统的0~10 mm宽筛分分布缩减为0~1 mm的窄筛分分布,在低床存量下实现足够高的循环流率,通过流态调控化学反应,强化低氮燃烧需要的还原性气氛,并为延长细颗粒石灰石在炉内的停留时间提供了保证,同时改善锅炉燃烧性能。更为重要的是,由于燃料粒度降低,化学反应速度即热量释放变化速率得以提高;辅助以循环干预措施,可提高传热率的变化速度,二者综合可以改善负荷变化率。燃料粒度的变化必然导致床料粒度降低,显著改善了深度低负荷能力以及低负荷下的NOx排放炉内控制能力。该思想得到模型验证:当燃料粒度由常规缩减到0~1 mm时,床料粒度大幅降低,稀相区物料悬浮浓度提高,循环流率提高了约27%;炉内还原性气氛得到增强,NOx原始排放浓度降低约35%;循环系统性能的改善可延长细颗粒石灰石在炉内的停留时间,提高脱硫反应效率,在钙硫比、NOx排放相同条件下,降低了SO2原始排放浓度;同时,燃烧效率显著改善,底渣含碳量降低89%、固体不完全燃烧热损失降低52%,表明PC-CFB燃烧技术在增强CFB锅炉运行灵活性、强化低氮燃烧、提升燃烧性能等方面更具优势。Under the background of dual-carbon target,the circulating fluidized bed combustion technology,as an important part of coal-fired power generation,realizes an efficient and clean utilization of inferior fuel and is also a main force to participate in deep peak regulation of power grid in the future.However,CFB boilers still have a lot of room for improvement in load regulation rate,NOxemission control at deep low and low loads,and heating surface wear.Therefore,the powdered coal circulating fluidized bed(PC-CFB)combustion technology is proposed.By reducing the fuel particle size from the wide sieve distribution of 0-10 mm to a narrow sieve distribution of 0-1 mm,a sufficiently high circulating flow rate can be achieved at a low bed stock.Regulating chemical reactions through flow regimes,the reducing atmosphere needed for low-NOxcombustion is strengthened,and the residence time of fine limestone in the furnace is extended,the combustion performance of the boiler can also be improved.More importantly,the rate of change in chemical reaction,i.e.heat release,increases due to the decrease of fuel particle size.Supplemented by cyclic interventions that can increase the rate of change in heat transfer rate,the combination of which can improve the rate of load regulation.The change of fuel particle size inevitably leads to the reduction of bed particle size,and significantly improves the deep low load capability and the in-furnace control of NOxemissions at low loads.This idea is confirmed by the modelling prediction,which shows that when the range of fuel particle size is reduced from the conventional size distribution to 0-1 mm,the average bed particle size decreases greatly and the material concentration in the dilute phase zone increases,and the circulating flow rate increases by about 27%.The reducing atmosphere in the furnace is enhanced,and the original emission concentration of NOxis reduced by about 35%.The improved performance of the circulation system can prolong the residence time of fine limestone in the fu

关 键 词：粉煤 循环流化床 燃料粒度 运行灵活性 排放控制 燃烧性能 

分 类 号：TK16[动力工程及工程热物理—热能工程]