基于封闭耗氧试验的采空区自燃危险性研究

On the spontaneous combustion risk in the goaf based on the closed oxygen consumption experiment

为准确判断雁南矿采空区遗煤的自燃危险程度,提出由封闭耗氧试验测定所需的窒熄(临界)氧气体积分数(12%)、最短自然发火期(47 d)。利用雁南矿10130101综放工工作面束管收集的气体实测数据,采用氧气体积分数法确定该工作面采空区的自燃氧化带宽度。鉴于由实测数据无法确定采空区内连续的氧气体积分数分布,对现场工作面风速、压差和采空区氧气体积分数等实测数据进行分析计算,建立此工作面的物理模型,考虑重力和上行通风对采空区流场的影响,采空区冒落介质非均匀且按照"O"形分布,利用Fluent软件对雁南矿10130101综放工作面采空区的流场进行数值模拟。将仿真与实测的采空区氧气体积分数的分布进行对比验证,最终得到采空区自燃氧化带的最大宽度为122 m,判断当前推进速度(5 m/d)下该工作面采空区自燃的可能性低。矿上长期生产结果验证了利用封闭耗氧试验判断采空区自燃危险性的准确性。

The present paper intends to make an experiment of the closed oxygen consumption amount to determine the(critical)oxygen volume fraction(12%)and the shortest spontaneous combustion period(47 days)of the coal samples in the Yannan mine.The research goal is to assess accurately the risk degree of the spontaneous combustion in the goaf of the Mine.As a result,we have collected the corresponding data needed through the beam tube monitoring and other related technical means,so as to analyze the needed data and work out the oxygen distribution situation in the goaf of 10130101 fully mechanized top-coal caving face of the said mine and the air leakage rate per 143 m^(3)/min,in addition to the pressure difference between the 2 ends of 58.598 Pa.According to the oxygen concentration rate comparison method,the measured width of the spontaneous combustion oxidation zone in the goaf of the working face has been worked out at about 120 m,whereas the flow field in the goaf of10130101 fully mechanized top-coal caving face in the said mine can be simulated by using a simulation software known as the Fluent.And,then,on account of the influence of the gravity and the working face inclination angle on the gas flow field in the goaf,the caving medium has been found non-uniformed with the unevenly distributed in accordance with the"O"type.At the same time,a specific UDF control program can be gained from the closed oxygen consumption experiment in combination with the oxygen consumption velocity parameters of the Yannan Mine Sample.Furthermore,it would be possible to gain the continuous distribution of the oxygen volume fraction flow field in the goaf which can be verified through a comprehensive simulation in the corresponding positions in the goaf as compared with the measured oxygen volume fraction for verification.Thus,eventually,the maximum width of the said spontaneous combustion oxidation zone in the goaf of the working face has been determined to be equal to 122 m,while the lowest daily advancing speed of the working face has been confirmed to be 2.5957 m/d,with the current advancing speed of the working face being settled down to be 5 m/d,so as to confirm the possibility of the spontaneous combustion of the remaining coal layer in the goaf turning to be very low.Hence,the paper has made it possible to determine the oxygen volume fraction index of the"3 zones"smotherextinguishing zone of the spontaneous combustion in the goaf zones through the closed oxygen consumption experiment,which helps to provide a new scientific basis for fire prevention and control in the goaf zones of the given coal mine.