褐煤高水分和高挥发分不利于运输和储存，且会降低锅炉燃烧效率，低温烘焙提质作为一种褐煤提质常用技术，能有效降低燃料中水分并提升燃料品质，显著改变褐煤燃烧特性。为研究低温烘焙提质对褐煤着火特性的影响，利用平面火焰燃烧系统并结合CMOS相机研究了不同热协流温度(1 473、1 673和1 873 K)和O2体积分数(5%、10%和20%)下低温烘焙预处理（200、250和300 ℃）对褐煤着火燃烧特性的影响，并分析低温烘焙提质对着火延迟距离和火焰亮度的影响。结果表明，经低温烘焙预处理的褐煤颗粒在相同热协流温度和O2浓度条件下的着火延迟距离稍大于原始褐煤颗粒；O2体积分数为5%时，200 ℃烘焙褐煤的着火延迟距离在热协流温度1 473、1 673和1 873 K时较原始褐煤颗粒分别增加了0.24、0.28和0.13 cm；此外，不同烘焙温度下煤粉颗粒的着火位置较褐煤均有所延迟，且升高烘焙温度会降低褐煤着火距离，在1 673 K、O2体积分数5%下，烘焙温度200、250和300 ℃时对应的着火延迟距离较褐煤的增加值分别为0.28、0.16和0.11 cm。

High moisture and volatile content of lignite are not conducive to transportation and storage, and can reduce boiler combustion efficiency. As a common technology for lignite upgrading, low-temperature torrefaction and upgrading can effectively reduce moisture in fuel and improve fuel quality, significantly change the combustion characteristics of lignite. In the diffusion-flamelet-based Hencken burner experimental facility, the effect of torrefaction temperature (200, 250 and 300 ℃) on the ignition and combustion characteristics of lignite were carried out via CMOS camera. The effect of the co-flow temperatures (1 473, 1 673 and 1 873 K), oxygen concentrations (5%, 10% and 20%) were considered. Results show that the ignition delay distance of torrefacted lignite particles is slightly larger than that of raw lignite particles under the same co-flow temperature and oxygen concentration. Under the oxygen concentration of 5%, the ignition delay distance of the torrefacted lignite at 200 ℃ are increased by 0.24, 0.28 and 0.13 cm when comparing with that of the raw lignite particles, respectively. Additionally, the increase of torrefaction temperature significantly decreases the ignition delay distance of lignite particles. Under case of 1 673 K and 5% O2, the ignition delay distance of torrefacted lignite at 200, 250 and 300 ℃ are increased by 0.28, 0.16 and 0.11 cm when comparing with that of raw lignite, respectively.

0 引言

1 试验

2 结果与讨论

   2.1 煤粉颗粒燃烧火焰图像

   2.2 褐煤颗粒的着火延迟距离

   2.3 不同烘焙温度下煤粉的着火延迟距离

3 结论