基于颗粒示踪的循环流化床锅炉煤燃烧残碳量预测

Carbon residue prediction of coal combustion in circulating fluidized bed boiler based on particle tracer

锅炉燃烧残碳量是反映锅炉燃烧效率的重要指标,预测其数值对锅炉运行调整及设计有着重要意义。依据试验测量的煤颗粒在炉内的运动路径及停留时间开展炉膛出口含碳量预测计算,探究停留时间、炉膛温度、煤种、过量空气系数对煤颗粒残碳量的影响。结果表明,停留时间越长的煤颗粒残碳量越低;床温从800℃升高到900℃,残碳量降低约40%~50%;过量空气系数从1.05增大到1.3,残碳量降低10%~30%;煤种的特性是影响残碳量的关键因素,煤的挥发分含量、固定碳含量、反应活性决定了煤的燃尽。通过与循环流化床锅炉设计方法计算含碳量对比以及实炉试验数据验证,证明煤颗粒残碳量基于运动轨迹方法预测结果的合理性。

The carbon residue is essential for reflecting the combustion efficiency of CFB boiler,the accurate prediction of carbon residue has significance for CFB operation and design.Based on the trajectory and residence time of particles in the furnace,the carbon content of coal particles out of the furnace was calculated.The effects of residence time,furnace temperature,coal rank,and excess air ratio were investigated.It is found that the coal particle with longer residence time has lower carbon content.When the bed temperature increases from 800℃to 900℃,the carbon residue decreases by about 40%-50%.Increasing the excess air ratio from1.05 to 1.3,the carbon residue reduces by 10%-30%.The rank of coal is the key factor to carbon residue.The volatile,fixed carbon content and reactivity of coal determine the burnout behavior.By comparing the calculated results by the CFB design method and the experimental data,it is proved that the prediction of residual carbon based on the trajectory method is reasonable.