摘要:
为揭示不同惰气预防煤自燃的效果及阻燃规律，通过开展惰气等温动态驱替不同粒径煤体中氧气实验，分析了He，N2，CO2驱替出氧气浓度、驱替时间、驱替量及驱替速率等表征驱替过程的参数。实验结果表明：① 惰气驱替出的氧气浓度变化可划分为3个阶段。首先，惰气驱替出的是气体检测仪内管路中的氧气，体积分数为21%左右；然后，惰气驱替出煤样罐中游离态和部分吸附态氧气，氧气浓度保持平稳；最后，惰气已经全部驱替出煤样罐中游离态氧气，氧气浓度呈负指数变化。② 不同惰气驱替煤体中氧气的时间总体上随着粒径增大而下降；CO2驱替氧气的总时间最长，He次之，N2最短。③ 对于同一粒径，氧气驱替量呈现出明显的拐点，拐点出现前氧气驱替量基本上呈线性增加，拐点出现后氧气驱替量随时间增加缓慢增加并最终保持平稳；不同惰气作用下氧气累计驱替量均随着粒径增大而减少，CO2对氧气的累计驱替量最大，He次之，N2最小。④ 不同惰气作用下氧气驱替速率均呈先紊乱后稳定下降的特征，其中CO2驱替氧气的速率紊乱阶段尤为明显；在氧气驱替速率稳定下降阶段，同一时间内氧气驱替速率随着粒径增大基本上呈减小趋势。
Abstract:
In order to reveal the effect of different inert gases in preventing coal spontaneous combustion and the law of flame retardation, the experiment of isothermal dynamic displacement of oxygen by inert gas in coal with different particle sizes is carried out, and the concentration of oxygen, displacement time, displacement volume, displacement rate and other parameters that characterize the displacement process of He, N2 and CO2 are analyzed. The experimental results are showed as follows.① The concentration change of oxygen displaced by inert gas can be divided into three stages. Firstly, the inert gas displaces the oxygen in the pipeline of the gas detector, and the volume fraction is about 21%. Secondly, the inert gas displaces free and partially adsorbed oxygen in the coal sample tank, and the oxygen concentration remains stable. Thirdly, the inert gas has completely replaced the free oxygen in the coal sample tank, and the oxygen concentration shows a negative exponential change. ② The time for different inert gases to displace oxygen in coal generally decreases as the particle size increases. The total time for CO2 to displace oxygen is the longest, followed by He, and N2 is the shortest. ③ For the same particle size, the amount of oxygen displacement shows an obvious inflection point. Before the inflection point, the amount of oxygen displacement basically increases linearly. After the inflection point, the amount of oxygen displacement increases slowly with time and finally remains stable. The accumulative amount of oxygen displacement under different inert gases decreases with the increase of particle size. The accumulative displacement of CO2 to oxygen is the largest, followed by He, and N2 is the smallest. ④ The oxygen displacement rate under the effects of different inert gases is characterized by first disorder and then stable decrease. Among them, the disorder stage of CO2 displacement is especially obvious. In the stable decrease stage of oxygen displacement rate, the rate of oxygen displacement basically decreases with the increase of particle size at the same time.
百度学术
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