王铭明, 汪晨, 于浩, 胡圣明. 不同温度下煤样氧化热解气体产物在煤中吸附特性的实验研究[J]. 煤炭学报, 2020, 45(S1): 284-290. DOI: 10.13225/j.cnki.jccs.2019.1272
引用本文: 王铭明, 汪晨, 于浩, 胡圣明. 不同温度下煤样氧化热解气体产物在煤中吸附特性的实验研究[J]. 煤炭学报, 2020, 45(S1): 284-290. DOI: 10.13225/j.cnki.jccs.2019.1272
WANG Mingming, WANG Chen, YU Hao, HU Shengming. Experimental investigation on adsorption characteristics of in coal gas mixture from coal self-heated under different temperatures[J]. Journal of China Coal Society, 2020, 45(S1): 284-290. DOI: 10.13225/j.cnki.jccs.2019.1272
Citation: WANG Mingming, WANG Chen, YU Hao, HU Shengming. Experimental investigation on adsorption characteristics of in coal gas mixture from coal self-heated under different temperatures[J]. Journal of China Coal Society, 2020, 45(S1): 284-290. DOI: 10.13225/j.cnki.jccs.2019.1272

不同温度下煤样氧化热解气体产物在煤中吸附特性的实验研究

Experimental investigation on adsorption characteristics of in coal gas mixture from coal self-heated under different temperatures

  • 摘要: 煤的孔隙结构为煤自身热解气体混合物提供了贮存及运动的场所。煤的氧化热解气体混合物在煤的孔隙中运动及吸附特性的研究对准确评估煤矿内源火灾的风险具有重要意义。自行设计了一套集煤颗粒自热反应与吸附热解气体混合物于一体的实验装置,对不同温度下煤自热过程中释放气体混合物的成分,以及该气体混合物在煤孔隙中运动及被吸附进行了一系列的实验研究。研究结果表明:①检测吸附柱入口处各种气体的浓度可确定煤自热氧化反应时的释放特性。在不同温度条件下,一氧化碳和二氧化碳的体积分数最高,接近9%,乙炔的体积分数最低,在10×10-6 mg/m2以下。②随着实验温度的改变,煤释放各种气体的体积分数随之改变;煤氧化热解气体混合物中多数成分的体积分数随着温度的升高而升高,只有乙烷、丙烷和氢气的浓度随温度的升高呈不规则变化。③在气体混合物穿透过煤颗粒的吸附特性实验中,计算每种气体成分在吸附柱出入口处体积分数的比值可确定该气体在煤孔隙中运动时被吸附的特性;临界温度较低的气体(如CO,H2)不容易在煤中被吸附;二氧化碳和乙烷的临界温度(分别为31.3和32.8℃)比较接近,然而,二氧化碳和乙烯较乙烷的出入口体积分数比值要低5%~10%,这是因为小分子气体(低于0.4 nm)更容易渗透到煤的微孔隙中,从而更容易发生吸附,而像乙烷、丙烷这些大分子气体根本无法渗透到煤的微孔隙中。因为如乙烯、丙烯及乙炔等气体,在2个碳原子之间有1个不稳定多重化学键(由1个基本σ型键和1个π键组成),有利于这种气体与煤的表面发生反应,形成新的化学键。这说明含不饱和烃比例高的气体(如C3H6,C2H2)更容易被吸附,还与气体分子化学键的性质有关。此外,吸附实验可以确定气体在煤中的吸附特性不但与气体自身的物理化学特性密切相关,还与煤的性质有关。

     

    Abstract: The pore structure of coal provides a place for pyrolytic gases from coal storage and movement. The study of the gases movement in coal pore is of significance to the accurate assessment of internal fire risk. The mixture of gases released from the coal self-heating process can move in its pore and be adsorbed by coal. A set of self-designed experimental device is used to study the multi-component gases mixture released during the self-heating process of coal and the flow in the pore of coal particles. The results show that ①the concentration of various gases at the outlet of the reactor can be determined by the characteristics of coal self-heating. Under different temperatures,the concentrations of carbon monoxide and carbon dioxide are the highest,nearly 9%,and the concentration of acetylene is the lowest,less than 100 mg/m3. ②With the different experimental temperatures,the concentration of each component of the gases mixture released from coal changes accordingly. The concentrations of most components in the gases mixture from coal oxidation and pyrolysis are increased with the increase of temperature,while the concentrations of ethane,propane and hydrogen vary irregularly with the temperature. ③In the experiment of gases adsorption in coal,the adsorption of each gas can be determined by the ratio of the concentration of each gas at the entrance and exit of the adsorption column. Gases with a lower critical temperature (such as CO,H2) are not easily adsorbed in coal. The critical temperature (31.3℃ and 32.8℃,respectively) of ethane and carbon dioxide is close,while the concentrations at the inlet and outlet of carbon dioxide and ethylene are 5%~10% lower than that of ethane because the small molecule gases(below 0.4 nm) are easier to penetrate into the micro porosity of coal,which adsorptions are more likely to happen,and large molecules (such as ethane,propane) cannot infiltrate the coal micropore. Some gases such as ethylene,propylene and acetylene,which have an unstable multiple bond between two carbon atoms (1 α bond and 1 π bond)can help the gases react with the surface of the coal to form new bonds. This indicates that the gases with a high proportion of unsaturated hydrocarbons (such as C3H6,C2H2) are adsorbed more likely,and it is also related to the nature of the chemical bonds of the gas molecules. In addition,it can be ascertained that the adsorption characteristics of various gases in coal are closely related not only to the physical and chemical properties of gases,but also to the coal properties.

     

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