浸水时长对未干燥煤低温氧化特性的影响实验研究

    Experimental study on the effect of immersion duration on low temperature oxidation characteristics of undried coal

    • 摘要: 为模拟井下浸水煤样的低温氧化过程,探究浸水时长对未干燥煤低温氧化特性的影响。通过自主开发的气浴式煤低温氧化实验系统,对安泽矿区12组不同浸水时长的未干燥煤样进行程序升温实验,分析了煤在低温氧化不同阶段的气体产出和表观活化能变化规律,并基于实验结果探讨了其中的微观机理。结果表明,不同温度阶段,不同浸水时长对煤的低温氧化能力有着不同的影响:在75 ℃之前,水分对煤氧反应起到抑制作用,并且浸水时间越长,抑制效果越显著,出口氧气体积分数和缓慢氧化(SI)阶段的表观活化能随浸水时间增加逐渐增大,标准耗氧速率和标准CO生成速率随浸水时间增加逐渐减小;75 ℃之后,水分对煤氧反应起到促进作用,并且浸水时间越久,促进作用越明显,出口氧气体积分数和加速氧化(SII)阶段的表观活化能随浸水时间增加逐渐减小,标准耗氧速率和标准CO生成速率随浸水时间增加逐渐增大。根据推断,这与水浸后煤样内部发生的一系列复杂物理化学变化有关:在75 ℃之前,煤体中的水分吸热蒸发,阻碍氧气扩散,抑制了煤氧反应;而在75 ℃之后,煤中水分大量蒸发,在水的侵蚀作用下,煤体的物理结构发生改变,同时也暴露出更多的化学基团,一些化学反应释放热量,共同促进煤氧反应。

       

      Abstract: In order to simulate the low-temperature oxidation process of coal samples immersed in mine water and explore the effect of immersion time on the low-temperature oxidation characteristics of undried coal, through the self-developed gas-bath coal low-temperature oxidation experimental system, programmed temperature experiments were conducted on 12 groups of undried coal samples with different immersion durations in Anze Mining Area. The gas production and apparent activation energy changes of coal at different stages of low-temperature oxidation were analyzed, and the microscopic mechanism was discussed based on the experimental results. The results show that different temperature stages and immersion durations have varying effects on the low-temperature oxidation ability of coal. Before 75 ℃, moisture has an inhibitory effect on coal oxygen reaction and the longer the immersion time, the more significant the inhibitory effect, specifically, the volume fraction of exported oxygen and the apparent activation energy during the slow oxidation (SI) stage gradually increase with increasing immersion time, while the standard oxygen consumption rate and standard carbon monoxide generation rate gradually decrease with increasing immersion time; after 75 ℃, moisture promotes the coal oxygen reaction, and the longer the immersion time, the more obvious the promoting effect, specifically, the export oxygen volume fraction and apparent activation energy of the accelerated oxidation (SII) stage gradually decrease with increasing immersion time, while the standard oxygen consumption rate and standard carbon monoxide generation rate gradually increase with increasing immersion time. According to the inference, this is related to a series of complex physical and chemical changes that occur inside the coal sample after water immersion, before 75 ℃, the moisture in the coal absorbs heat and evaporates, hindering the diffusion of oxygen and inhibiting the coal oxygen reaction; after 75 ℃, a large amount of water evaporates from the coal, and under the erosion of water, the physical structure of the coal body changes, while also exposing more chemical groups. Some chemical reactions release heat, jointly promoting coal oxygen reactions.

       

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