宁夏灵新矿不粘煤的孔隙结构特征及其对CO吸附的影响

Adsorption of CO in Ningxia Lingxin non-caking coal based on fractal dimension

为研究宁夏灵新矿不粘煤的孔隙结构特征对CO吸附的影响,开展了低温液氮吸附试验和CO吸附试验,分析了不粘煤在不同粒径下的孔隙结构特征,讨论了比表面积和孔容分布对CO吸附的影响;利用FHH模型计算了煤样孔隙的分形维数,建立了分形维数与Langmuir参数V_(L)、P L之间的关系,明确了煤样孔隙分形特征对CO吸附的影响。结果表明:在各类孔隙结构中,微孔数量最多;随着煤样粒径减小,煤样总比表面积和总孔容均增加,煤样总比表面积、总孔容与V L呈正相关;煤样在低、中、高3个压力阶段具有不同的吸附特性和分形特征,煤样对CO吸附受分形维数D_(1)和D_(2)影响,随着D_(1)增大,煤样对CO的吸附能力增强,随着D_(2)增大,煤样对CO的吸附能力逐渐减弱;分形维数D 1与V L呈正相关,与P_(L)呈负相关,分形维数D_(2)与V_(L)和P_(L)之间相关性不明显。研究结果对矿井煤自燃火灾指标性气体的精准监测具有指导意义。

In order to study the influence of fractal dimension on the adsorption of CO by non-caking coal in Lingxin coal mine of Ningxia,low temperature liquid nitrogen adsorption test and CO adsorption test were carried out.The pore structure characteristics of non-caking coal under different particle sizes were analyzed,and the effects of specific surface area and pore volume distribution on CO adsorption were discussed.The FHH model was used to calculate the fractal dimension of the pore of the coal sample,and the relationship between the fractal dimension and the Langmuir parameters V_(L) and P_(L) was established,and the influence of the fractal characteristics of the pore of the coal sample on the CO adsorption was clarified.The results show that the number of micro-pores is the largest in all kinds of pore structures.With the decrease of coal particle size,the total specific surface area and total pore volume of coal samples increase.The total specific surface area and total pore volume of coal are positively correlated with V L.Coal samples have different adsorption characteristics and fractal characteristics at low,medium and high pressure stages.The adsorption of CO by coal samples is affected by fractal dimension D_(1) and D_(2).With the increase of D_(1),the adsorption capacity of coal samples to CO increases.With the increase of D_(2),the adsorption capacity of coal samples to CO gradually decreases.The fractal dimension D_(1) is positively correlated with V_(L) and negatively correlated with P L.The correlation between fractal dimension D_(2) and V_(L) and P L is not obvious.The research results can provide a theoretical basis for the accurate monitoring of index gas in coal spontaneous combustion fires.