空气湿度对煤自燃特性影响的试验研究

为研究空气湿度对煤自燃特性的影响,运用程序升温试验台,在不同环境湿度条件下,对黄陵2号矿4#煤层煤样进行程序升温,分析不同温度下的气体成分,计算煤样在不同温度和湿度条件下的耗氧速率、CO和CO_2产生率,以及煤氧化的表观活化能。结果表明:与在干燥的空气中氧化相比,煤在加湿空气中的耗氧速率、CO和CO_2产生率升高,活化能降低,表明加湿有利于煤自燃;随空气湿度增加,煤体的耗氧速率、cO和CO_2产生率先升高后降低,活化能先降低后增加,表明存在一个最容易使煤氧化自燃的临界空气湿度;黄陵2号矿4#煤层煤样的临界相对湿度为25%左右。

Air humidity influential characteristic features of the coal spontaneous combustion

In order to investigate the impact of the air relative humidity on the characteristic parameters of the coal spontaneous combustion,the paper focuses itself on the temperature program parameters through experiments.For this purpose,we have collected coal samples from No.4 coal seam of Huangling Ⅱ mine.In doing so,we had broken the coal samples into pieces and classified them into five different particle sizes,namely,＜ 0.9 mm,0.9-3 mm,3-5 mm,5-7 mm and 7-10 mm for our five mixed coal samples.When doing the experiments,we put the mixed coal samples into laboratory fumace and controlled the relative humidity of air in the laboratory furnace.Everything done,we began to carry out the oxidation by varying the temperature programmed parameters in the system.In proceeding with our experiments,we have to find out the oxygen consumption rate,the generation rate of CO and that of CO2 and the apparent activation energy by measuring the concentrations of gases at different temperatures in the environment to find the impact of different degrees of the air relative humidity on the variation regularities of the parameters concerned through comparative analysis.Then,we found the influence law of relative humidity on the spontaneous combustion.The experimental results we have gained show that under the environment of humid air,higher oxygen consumption rate and higher generation rates of CO and CO2 than that the normal environment of dry air are to be given.And,since the activation energy is lower,it would be possible to indicate a more suitable condition for spontaneous combustion.What is more,with the increase of the air relative humidity,the oxygen consumption rate,the generation rate of CO and that of CO2 tend also to increase at first and then decrease,whereas the activation energy tends to decrease at first and then to increase.To be exact,it is due to the existence of the critical relative humidity of air that makes it highly liable to lead to the oxidation and spontaneous combustion of the coal in the mine.On the basis of the above study,the critical relative humidity of air of No.4 coal seam in Huangling Ⅱ mine has been found around 25％.