新型工业煤粉锅炉运行及排放特性试验探究.doc

新型工业煤粉锅炉运行及排放特性试验探究 　　摘要： 为了改善工业煤粉锅炉的NOx排放特性并保证其燃烧效率，对某新型空气分级燃烧器进行了现场试验.通过改变煤种、过量空气系数及三次风开度，分析了锅炉NOx及CO排放质量浓度的变化规律，同时采用反平衡法对锅炉的热效率进行了测算.试验结果表明，工业煤粉锅炉能达到较高的热效率；煤中氮含量及挥发分含量与NOx的生成具有一定的相关性，氮含量越高，NOx排放质量浓度越高，挥发分含量越低，NOx排放质量浓度越高；过量空气系数和三次风开度不仅影响锅炉燃烧效率，而且对NOx排放的影响也较为显著.研究发现，试验锅炉的排烟氧含量（质量分数）应控制在2.5%～2.6%之间较为合理，三次风开度为39%时NOx排放质量浓度最低. 关键词： 工业锅炉； 煤粉； 分级燃烧； 过量空气系数； 三次风； 氮氧化物 中图分类号： TK 227 文献标志码： A Abstract： To improve the nitrogen oxides （NOx） emission characteristics of industrial pulverized coal boiler and guarantee its combustion efficiency，field test was carried out on a model of air staged burner newly developed by a company in Shanghai.The emission characteristics of NOx and carbon monoxide （CO） were analyzed by changing the coal type，excess air coefficient and opening of the tertiary air.At the same time，Thermal efficiency of the boiler was calculated by antibalance method.Experimental results showed that high thermal efficiency of this industrial boiler could be achieved.The nitrogen content and volatile content in the coal samples had some correlations with NOx generation.The higher the nitrogen content，the higher the NOx emission was.The lower the volatile content，the higher the NOx emission was.The excess air coefficient and opening of the tertiary air not only had influences on the combustion efficiency of the boiler，but also had significant influence on the NOx emission.It was reasonable to control oxygen content in the flue gas between 2.5%and 2.6%.The lowest NOx emission was achieved when the opening of the tertiary air was 39%. Keywords： industrial boiler； pulverized coal； staged combustion； excess air coefficient； tertiary air； nitrogen oxides 中国燃煤工业锅炉总量约为57万台，年耗燃料约4亿t标准煤，污染物排放总量接近电站锅炉，在许多城市甚至超过电站锅炉的排放[1]，在燃烧过程中产生的NOx更直接危害了人类赖以生存的环境.上海等重点地区燃煤锅炉的NOx排放极限值为200 mg?m-3[2]，而目前的工业锅炉大多没有达到这一标准，因此对燃烧器进行研发及改造就变得十分紧迫.本文通过对某新型空气分级燃烧器进行现场试验，测算锅炉运行效率并研究不同煤种、过量空气系数及三次风开度对氮氧化物的生成和燃烧效率的影响，为燃烧器的平稳运行和进一步改造提供依据. 1NOx生成机理及空气分级燃烧技术 1.1NOx生成机理 燃煤烟气中的NOx大部分是在燃