褐煤半焦旋风燃烧数值模拟

Numerical simulation on combustion of lignite semi-char in cyclone furnace

褐煤经低温热解后残余固体半焦的利用一直制约我国低阶煤分质转化和高效清洁利用的发展。本文采用旋风炉燃烧褐煤半焦的方法,通过Fluent软件模拟了不同过量空气系数下旋风炉模型内温度、速度、组分体积分数的分布情况,同时对焦炭转化率和NO_x排放特性进行了研究。结果表明:本文所采用的数值模拟方法可以准确地描述褐煤半焦在旋风炉内的燃烧情况;过量空气系数在0.5~0.7时,半焦在旋风炉内的转化率均大于98.4%,且NO_x排放质量浓度较低,最高仅为144mg/m3。采用旋风炉燃烧可以实现褐煤半焦的高效清洁利用,对我国低阶煤转化利用的发展具有重要意义。

The portion of lignite reserves in China＇s coal resources is huge. The efficient and clean techniques of utilizing the lignite semi-char are the main factors restricting the development of lignite pyrolysis and its cascade utilization. The cyclone furnace combustion technique is proposed to burn the lignite char. The dis- tribution of temperature, velocity, species concentration of the lignite semi-char burning in a cyclone furnace is simulated using the Fluent software. Moreover,the carbon conversion rate and NOx emission characteristics of the lignite semi-char are investigated, and the experimental data are compared with the simulation results. The results show that,the model used in the simulation can accurately descript the combustion of lignite char in cyclone furnace. The burn-out rate of the semi-char is greater than 98.4% and the concentration of NOx is less than 144rag/m3 when the excess air ratio is between 0.5 and 0.7. It is proved that burning lignite semi-char in cyclone furnace is an efficient and clean way to utilize the lignite semichar.