再燃烧条件下煤焦还原NO特性的研究

STUDY ON BEHAVIOR OF COAL CHAR IN REDUCTION OF NO UNDER CONDITION OF REBURNING

在携带流反应装置中,研究了不同煤焦制备和反应条件下煤焦异相还原NO的特性,分析了煤种、热解条件（热解温度、煤粉热解时粒径和热解气氛）和反应条件（煤焦还原NO时的反应温度、环境气氛）等因素对煤焦还原NO特性的影响。结果表明,挥发分含量较高的煤种,其煤焦对NO的还原能力较强;热解温度的提高导致生成煤焦还原NO能力下降;小粒径煤粉热解生成的煤焦较大粒径煤粒热解生成的煤焦对NO的还原率高;煤粉在一次燃烧区过量空气系数为1.0-1.2的烟气气氛中热解时,生成的煤焦对NO的还原能力无明显差别;参与反应的煤焦颗粒周围烟气气氛对煤焦还原NO的影响较大,在SR1为0.9-1.3范围内,NO还原效率呈现两头高中间低的特性,且当SR1=1.1时,NO还原率最低;在高温氧化性气氛中,随反应温度的提高,煤焦还原NO的效率增加。

In an entrained flow reactor,the behavior of coal chars prepared from four coal sorts under different reaction conditions have been studied,the effects of coal sorts,pyrolysis condition（i.e.pyrolysis temperature,particle size and atmosphere under pyrolysis）,and reaction conditions（including reaction temperature and ambient atmosphere etc） upon behavior of coal char in reduction of NO being analysed.Results show that the efficiency of NO redution increases along with increasing volatile matter in coal sort;the enhancement of pyrolysis temperature leads to decrease the reduction ability of the produced coal char;the reduction rate of coal char produced from pulverized coal with small particle size is higher than that from larger particle size;when pyrolysis of pulverized coal is in the primary combustion zone and in an atmosphere of excess air coefficient to be 1.0-1.2,the coal chars produced haven＇t obvious difference in ability of NO reduction;the particle size of coal char participating into reaction and the ambient atmosphere of flue gas have larger effect upon ability of coal char in reduction of NO;in the event of stoichiometric ratio=0.9-1.3,the efficiency of NO reduction appears high at two ends,and low at the middle,the efficiency to be minimum at SR1=1.1;in high temperature oxidative atmosphere,the efficiency of NO reduction increases along with the reaction temperature.