水对氧煤燃烧方式下煤粉热解及燃烧过程的影响  

Effect of water on pyrolysis and combustion process of coal during oxy-coal combustion

作　　者：罗嘉[1] 张曦[1] 吴望晨[2] 王超[2] 刘小伟[2] 

机构地区：[1]广东电网公司电力科学研究院,广东广州510080 [2]华中科技大学煤燃烧国家重点实验室,湖北武汉430074

出　　处：《热力发电》2015年第8期62-67,共6页Thermal Power Generation

基　　金：国家自然科学基金项目(51276072);国家重点基础研究发展计划(973计划)(2013CB228501);煤炭联合基金重点项目(U1261204)

摘　　要：为了探究湿式氧煤燃烧过程产生的高体积分数水对煤粉脱挥发分、煤焦气化、颗粒燃尽及CO生成特性的影响,利用自行搭建的沉降炉系统,在0.2s,0.3s和0.5s停留时间条件下分别进行了模拟烟气气氛下的煤粉热解和燃烧实验。其中,热解实验采用纯N2气氛、纯CO2气氛和CO2+水(不同体积分数比)气氛,燃烧实验则在此基础上分别加入了体积分数为5%,10%,21%和30%的O2来替换气氛中的N2或CO2。结果表明:相较于空气燃烧,氧煤燃烧中的高体积分数CO2会抑制煤粉挥发分的析出,而高体积分数水的加入则会提高氧煤燃烧初期煤粉脱挥发分的速率,且在煤粉热解阶段,水和CO2不会与煤焦发生气化反应;水在高氧体积分数、足够的停留时间条件下对煤粉燃尽率基本无影响,但会降低低氧体积分数条件下的煤粉燃尽率;水能够促进CO的氧化,从而降低炉内的CO体积分数。To investigate the effect of high concentration water on coal volatilization,char gasification,char particle burnout and CO generation during wet oxy-coal combustion,the coal pyrolysis and combustion experiments were carried out in simulated flue gas atmospheres on a self-built drop tube furnace,with the particle residence time in the reactor of 0.2s,0.3sand 0.5s.The pyrolysis tests were conducted in pure N2 atmosphere,pure CO2 atmosphere and CO2 with different concentrations of steam atmosphere.On this basis,the combustion tests adopt O2 with volume fraction of 5%,10%,21% and 30%to take place the N2 or CO2in the pyrolysis atmospheres.the residence time of coal particles in the reactor during each test is0.2s,0.3sand 0.5s,respectively.The results indicate that,compared with air combustion,high concentration CO2 during oxy-coal combustion can inhibit the devolatilization of coal.The addition of high concentration H2 O during oxy-coal combustion can enhance the early stage devolatilization of coal,and the gasification reaction between char and H2 O or CO2didn＇t occur during the pyrolysis.The water nearly had no effect on burnout rate of the coal under conditions with high O2 concentration and long enough residence time,but it did decrease the burnout rate of coal under conditions with low oxygen concentration.The water can enhance the oxidation of CO,thus the CO concentration in the furnace was reduced.

关 键 词：氧煤燃烧 水 热解 脱挥发分 燃尽率 CO 停留时间 沉降炉 

分 类 号：TK224.1[动力工程及工程热物理—动力机械及工程]