一维炉内煤粉气流富氧着火距离试验

Experiment on ignition distance of pulverized coal stream with rich oxygen in one-dimensional furnace

针对火电锅炉在深度调峰过程中存在煤粉着火稳定性差的问题,提出富氧稳燃方法,并在一维炉内进行了煤粉气流点火试验,主要研究氧气浓度、一次风速和煤粉浓度对煤粉气流着火距离的影响。其中氧气浓度共取21%(空气)、25%、30%和35%,4个工况;一次风速共取18、23、28和33 m/s 4个工况;煤粉质量分数共取0.2、0.3、0.4、0.5和0.6 kg/kg(以每千克空气携带的煤粉质量计)5个工况。研究不同工况下煤粉气流着火距离的试验数据,并对试验数据及其变化规律进行详细分析。结果表明,氧气浓度每增加1%,着火距离缩短82.5 mm,但随氧气浓度的持续增大,对着火距离的影响逐渐变小;着火距离的变化率随风速的增加而增大,尤其当风速大于28 m/s后,风速对着火距离的影响非常大;煤粉浓度对着火距离的影响相对复杂,最佳煤粉浓度随氧气浓度的增大而增大;对比试验数据发现氧气浓度和一次风速对着火距离的影响大于煤粉浓度。最后利用试验数据拟合了氧气浓度和煤粉着火距离的数学模型,发现着火距离和氧气浓度之间存在指数函数关系。

In order to cope with the problems of combustion instability of pulverized coal during deep peak shaving in thermal power boilers,an oxygen-rich stable combustion method was proposed,and coal powder airflow ignition tests were conducted in a one-dimensional furnace.The influence of oxygen concentration,primary air velocity and pulverized coal concentration on ignition distance of pulverized coal was studied.Four oxygen concentrations were selected for study,i.e.21%(air),25%,30%and 35%in thd progress of experiments,the primary air speed was designed as 18,23,28 and 33 m/s respectively,and there werefive working conditions for coal powder concentration,namely 0.2,0.3,0.4,0.5,and 0.6 kg/kg(calculated by the mass of coal powder carried by each kilogram of air).The data from on the ignition distance of coal powder airflow were given under different working conditions,with detailed analysis on the experimental data and its variation rule.The results show that the ignition distance will be shortened by 82.5 mm along with the increase of 1%in oxygen concentration,but the values of the shorten of ignition distance decrease gradually with the continuous increase of oxygen concentration.The variation rate in ignition distance shows an increasing trend with the increase of primary air velocity,especially when the wind speed is greater than 28 m/s,the primary air velocity has a significant effect on ignition distance.The influence of pulverized coal concentration on ignition distance appears to be complex,as the optimum pulverized coal concentration increases with the increase of oxygen concentration.By comparing the experimental results,it is concluded that the influence of oxygen concentration and primary air speed on ignition distance is greater than that of pulverized coal concentration.Finally,the mathematical model with specific reference to oxygen concentration and ignition distance of pulverized coal was fitted by experimental data,which revealed that there is an exponential function relationship between ignition distance and oxygen concentration.