摘要
为探究多元气体对瓦斯爆炸的影响及机理,利用20 L爆炸球研究了多元混合气体[V(C2H6)∶V(C2 H4)∶V(CO)∶V(H2)=5∶5∶1∶1]分别对体积分数为7％、9.5％和11％甲烷的爆炸特性的影响规律,进一步利用CHEMKIN软件分析了不同工况下爆炸反应中关键自由基和基元反应的演化过程.结果表明,在体积分数7％甲烷中加入多元混合气体后,最大爆炸压力和最大爆炸压力上升速率增大,最大压力出现时间延后,在体积分数9.5％和11％甲烷中掺混多元混合气体后则出现相反的效果.对于体积分数7％甲烷,多元混合气体的掺混会使H·和·OH摩尔分数峰值上升,且达到峰值时间提前;对于体积分数9.5％和11％的甲烷,多元混合气体的掺混使H·摩尔分数峰值增大,O·和·OH摩尔分数峰值减小.最大爆炸压力与H·、O·和·OH摩尔分数峰值存在线性关系.最大爆炸压力与H·摩尔分数峰值呈分段线性关系,分割点出现在当量比为1和1.37处.总体来说,最大爆炸压力与摩尔分数峰值相关性随当量比增大而减小.R38(H+O2⇔O+OH)是主要的耗氧反应,也是控制甲烷消耗速率和爆炸反应能量释放的主要基元反应之一.因此,当O2较少时,R38反应受限,宏观上表现为高当量比时爆炸效应较弱.
Abstract
The influence of the multi-component mixed gas,with a composition and ratio of V(C2 H6)∶V(C2 H4)∶V(CO)∶V(H2)=5∶5∶1∶1,on the explosion characteristics of 7％,9.5％,and 11％volume fraction of CH4 was investigated using a 20 L spherical explosive device.Additionally,the CHEMKIN software was used to simulate the changes of H·,O·,and·OH in the explosion reaction of mixed gas with different ratios,as well as the sensitivity of elementary reactions.The relationship between the maximum explosion pressure and the peaks of the molar fraction of H·,O·,and·OH was analyzed.The results indicate that when adding the multi-component mixed gas to CH4 with a volume fraction of 7％,the maximum explosion pressure and the maximum rate of pressure rise increase,and the time to reach the maximum explosion pressure is delayed.However,when the volume fraction of CH4 reaches 9.5％or 11％,the opposite effect is observed.For CH4 with a volume fraction of 7％,the addition of the multi-component mixed gas increases the peaks of the molar fraction of H·and·OH and shortens the time to reach the peak.When the volume fraction of CH4 is 9.5％or 11％,the peak of the molar fraction of H·increases,while the peaks of the molar fraction of O·and·OH decrease.Besides,there is a linear relationship between maximum explosion pressure and the peaks of the molar fraction of H·,O·and·OH.Usually,the peaks of the molar fraction of H·,·OH,and maximum explosion pressure vary in the same trend,while the linear relationship between maximum explosion pressure and O·is bounded by an equivalence ratio of 1.When the equivalence ratio is less than 1,the higher the peak of the molar fraction of O·,the lower the maximum explosion pressure.Conversely,when the equivalence ratio is greater than 1,the trend is reversed.Furthermore,the correlation between maximum explosion pressure and the peaks of the molar fraction of free radicals decreases as the equivalence ratio increases.The sensitivity analysis indicates that R38(H+O2⇔O+OH)is the main oxygen-consuming reaction,consuming one mole of H·and producing one mole of O·and one mole of·OH,thereby increasing the destruction rate of CH4.Consequently,it is one of the fundamental reactions to control the CH4 consumption rate and the release of explosion reaction energy.Therefore,when there is less O2,the R38 reaction is constrained,macroscopically resulting in a weaker explosion effect at a high equivalence ratio.
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