摘要:
现有研究大多从煤自燃单组分气体或部分组分混合气体角度对瓦斯爆炸极限进行分析，而对煤自燃过程中不同阶段产生的混合气体对瓦斯爆炸极限的影响分析不足，对煤自燃与瓦斯爆炸的耦合致灾开展的实验研究较少。针对上述问题，通过模拟煤自燃实验装置研究了煤自燃过程中气体生成特征规律；采用20 L球形爆炸装置对瓦斯混合煤自燃各个阶段生成气体进行实验，研究了煤自燃气体对瓦斯爆炸下限的影响。实验结果表明,实验煤样自燃过程中产生的可燃性气体主要为CH4，CO，C2H4，C2H6，C2H2等，其中CH4和CO体积分数最高，最高体积分数分别为0.75%和0.37%；煤自燃不同阶段产生的可燃性气体含量随自燃时间的增加和温度的升高均呈现增大趋势，煤自燃加热初期，温度小于80 ℃主要产生了CH4，CO可燃性气体，CO可以作为煤自燃缓慢氧化阶段的标志气体；随着自燃时间的持续，温度超过80 ℃后，开始产生C2H4和C2H6，随后逐渐产生C3H8气体，C2H4的出现表明煤氧化进入了加速阶段；煤氧化自燃后期，大约到220 ℃时出现C2H2，此时煤进入激烈氧化阶段；低体积分数的CO能抑制瓦斯爆炸，高体积分数CO能促进瓦斯爆炸，导致爆炸压力变大，爆炸下限降低；煤自燃过程中产生的混合气体增大了瓦斯爆炸压力，爆炸下限最大降低了0.55%，瓦斯爆炸的危险性变大。
Abstract:
Most of existing research analyze gas explosion limit from single component gas or parial component mixed gas of coal spontaneous combustion, while analysis of gas explosion limit from mixed gas produced at different stages of coal spontaneous combustion is insufficient, and there are few experimental research on coal spontaneous combustion and gas explosion coupling disaster. In view of the above problems, the characteristic laws of gas generation in process of coal spontaneous combustion were researched by simulating experimental device of coal spontaneous combustion.The 20 L spherical explosion device was used to conduct the experiment about methane mix gas from coal spontaneous combustion at different stages,and effects of coal spontaneous combustion on the lower limits of gas explosion were studied.The experiment results show that main flammable gases of the coal sample spontaneous combustion are CH4, CO, C2H4, C2H6, C2H2， etc. Among these gases, CH4 and CO have the highest volume fraction, and the maximum volume fraction can reach 0.75% and 0.37% respectively. The content of flammable gases produced in different stages of coal spontaneous combustion is increased with the increase of spontaneous combustion time and temperature. CH4 and CO flammable gases are mainly produced at temperatures below 80 ℃ at the initial of coal spontaneous combustion, CO can be used as a marker gas for the slow oxidation stage of coal spontaneous combustion. As the time of spontaneous combustion continues,it starts to produce C2H4 and C2H6 after the temperature exceeds 80 ℃, and then C3H8 gas is gradually produced. At this time, the appearance of C2H4 indicates that the oxidation of coal has entered the acceleration stage. C2H2 is produced on the temperatures of 220 ℃ after the late stage of coal spontaneous combustion, at this point, the coal enters the intense oxidation stage. Low concentration of CO inhibits gas explosion, however, high concentration of CO promotes gas explosion, explosion pressure becomes larger, and lower explosion limit decreases. The mixed gas produced during the spontaneous combustion of coal increases the pressure of gas explosion, decreases the lower explosion limit by 0.55%,so increases the risk of gas explosion.
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