煤尘云着火敏感性影响因素的实验研究

为研究煤尘云的着火敏感性，选取3种典型煤尘-无烟煤、烟煤、褐煤，采用Godbert-Greenwald恒温炉装置，研究不同测试条件及煤尘种类对煤尘云最低着火温度的影响，以及惰性粉尘对煤尘云着火的抑制作用.研究表明:随着喷尘压力的增大，煤尘云最低着火温度先降低后升高，存在最佳喷尘压力为50 kPa，对应的煤尘云着火温度最低；随着煤尘粒径的增大，煤尘云最低着火温度呈线性升高的趋势；随着煤尘云浓度的增大，煤尘云最低着火温度先降低后升高；3种煤尘云均存在最佳着火浓度:无烟煤和烟煤为1.818 g/L，褐煤为1.364 g/L；煤尘云的最低着火温度随挥发分含量的增大而减小；挥发分质量分数小于15%的煤尘，灰分的阻燃作用明显，挥发分质量分数大于15%时，灰分的阻燃作用不明显；惰性粉尘对煤尘云着火的抑制效果:炭黑最强、粉煤灰次之，CaCO₃最弱. 

Experimental Study on Influenceing Factors of Ignition Sensibility of Coal Dust Cloud

In order to study the ignition sensibility of coal dust cloud, three kinds of typical pulverized coal-anthracite, bituminous coal and lignite-were chosen. And a Godbert-Greenwald oven was used to test the influence of different test conditions and coal dust types on the minimum ignition temperature (MIT) of coal dust and the suppression of coal dust cloud combustion by inert dust. The study found that the MIT of coal dust cloud first decreased and then rose with the increase of dust pressure. The optimal dust pressure was 50 kPa, on which condition the coal dust cloud ignition temperature arrived at minimum value. With the increase of coal dust particle size, the MIT of coal dust cloud showed a linear increase trend. With the increase of coal dust cloud concentration, the MIT of coal dust cloud decreased at first and then rose. For three kinds of coal dusts, all of them had a best ignition concentration. The best ignition concentration of coal-anthracite and bituminous coal was 1.818 g/L, and for lignite it was 1.364 g/L. The MIT of coal dust cloud decreased with the increase of volatility. For the coal dust which contained less than 15% volatility, the ash had obvious suppressive effect. When the content of volatility was more than 15%, the ash had little effect on the combustion of coal dust. The carbon black had the strongest inhibiting effect, coal fly ash had the second strongest inhibiting effect, and CaCO₃ had the weakest inhibiting effect on the MIT of coal dust clouds. The research results can strengthen the understanding of the combustion law of coal dust, and provide reference for the protection of coal dust fire and explosion and risk assessment of coal dust.