采空区煤体低温氧化特性的实验研究

Experimental study on low temperature oxidation characteristics of goaf coal

采空区的漏风条件以及氧气的不均匀分布严重影响煤体自然氧化状态。对煤样在氧气体积分数分别为3%、5%、7%、9%、12%、15%、18%、21%时进行低温氧化实验,利用气相色谱仪与傅里叶红外光谱仪,分析产气过程及官能团的变化规律。实验表明:脂肪烃CH2、CH3与羟基OH参与氧化反应,其占比随着氧化温度的升高而下降,且随着氧气体积分数的增加,降低幅度也在增大。在氧化升温中,羰基CO和羧基COOH的峰面积占比不断上升;当升温至230℃时,在氧气体积分数21%条件下,CO与COOH占比增长率分别为59.71%和49.96%;当氧气体积分数≤9%时,各活性官能团变化幅度相对较小,说明低氧条件对煤氧复合具有一定抑制作用;当氧气体积分数>9%,各活性官能团反应更容易被激活,温度超过70℃后,CO体积分数开始急剧升高,煤体更易进入快速氧化阶段。

This paper is focused on the solution to the air leakage conditions in the goaf and the uneven distribution of oxygen seriously affecting the natural oxidation state of coal.The study involves performing low temperature oxidation experiment on the coal samples subjected to oxygen concentration of 3%,5%,7%,9%,12%,15%,18%,and 21%,and analyzing the gas production process and the change law behind functional groups using gas chromatograph and Fourier infrared the spectrometer.Experiments show that:aliphatic hydrocarbons CH2,CH3 and hydroxyl OH participate in the oxidation reaction in which content tend to decrease depending on the increase in oxidation temperature,with an increase in decrease range following the increase of oxygen concentration;the entire oxidation heating process sees the proportion of the peak area of carbonyl CO and carboxyCOOH continue to increase;in the presence of the temperature increasing to 230℃and under the condition of 21%oxygen concentration,there are 59.71%and 49.96%respectively for the growth rate of CO and COOH content;the presence of the oxygen concentration less than or equal to 9%means a relatively small change range in each active functional group,showing that the low oxygen condition has a certain inhibitory effect on coal-oxygen recombination;the presence of the oxygen concentration greater than 9%makes it easier to allow the reaction of each active functional group to be activated;and the temperature exceeding 70℃is followed by the CO concentration starting to rise sharply,leaving the coal body more likely to enter the rapid oxidation stage.