【作者】 贾廷贵；

【导师】 刘剑；

【作者基本信息】 辽宁工程技术大学 ， 安全科学与工程， 2021， 博士

【摘要】 大倾角工作面采空区由于倾角大、垮落方式独特,导致采空区遗煤自燃较为隐蔽,自燃防治难度加大,同时由于大倾角采空区遗煤承压状态不同,破碎程度不同,且煤承压破碎特征尚不明确,存在大倾角采空区遗煤自燃监测难度大、准确性低,相关理论与实验研究结果对相关问题描述准确性欠佳的问题。因此,有必要开展大倾角采空区遗煤承压破碎特征与自燃规律实验研究,确定大倾角工作面采空区遗煤自燃规律,为大倾角遗煤自燃防治提供理论支撑。基于此,开展了大倾角工作面采空区应力分布特征数值模拟研究,并展开承压破碎特征实验研究,进而进行承压破碎煤的自燃实验研究和相似采空区遗煤自燃实验研究,最终确定采用遗煤自燃升温规律与自燃危险区域分布特征。研究结果表明:10-20mm粒度块煤平均压缩比分别为17%-40%,块煤的碎胀系数2.15-1.34,垂直应力2.76-22.06 MPa条件下平均压碎比为69.5%-86.6%,破碎后粒径5.0mm的质量比例与载荷呈显著负相关性,低于该粒径的质量比例与载荷之间具有显著正相关性。氮气环境下物理加热升温过程中,煤样温度随炉温(气流温度)以100℃为分界,具有先二次函数,后三次函数的非线性增长规律,氮气流量大小对煤样中温度的分布具有显著影响。空气环境下,遗煤氧化过程中,承压破碎煤的耗氧速率、CO产生速率、放热强度与压碎粒径质量比例之间是具有指数函数关系;不同漏风条件下,煤样的氧化温度也具有显著的空间位置差异性特征;风量120-1000mL/min条件下煤温40-70℃阶段内的表观活化能分别为 20.13kJ/mol、23.29 kJ/mol、14.57 kJ/mol、8.92 kJ/mol、19.29 kJ/mol。基于氮气和空气气氛环境下通过开展快速程序升温实验确定煤绝热氧化特征的5个假设,提出以空气与氮气环境的温差减去氮气环境对应温度氧化放热升温量计算绝热氧化放热升温量的方法。经计算在风量250mL/min、500mL/min、1000mL/min条件下的绝热自然发火期分别为:626.3h、274.4h、180.1h。以1:200的比例设计和构建了基于程序升温的采空区遗煤自燃相似实验系统,该系统主要包括供气系统、相似采空区及程序升温系统、负压通风系统、温度监测与采集系统4个子系统,并在抽出式上行通风条件下,通过不同倾角分别与氮气、空气环境下遗煤升温规律的对比发现:大倾角工作面采空区回风侧,相比水平工作面在回风侧更容易自燃,且在该区域中自燃危险性较大的部位为与切顶线1/6-1/2工作面长度的区域,以及开切眼的上隅角为最显著。且倾向中心区域以距离切顶线向采空区深部1/6-1/3以浅区域比水平工作面下相对更容易因为氧化而升温。同时除大倾角工作面条件下进风侧(倾向下部)除靠近切顶线1/6工作面长度的小部分区域与水平工作面自燃危险性相似外,其它采空区深部区域均难自燃。该论文有图121幅,表54个,参考文献112篇。更多还原

【Abstract】 Due to the characteristics of the large dip Angle and unique caving mode of goaf in large dip Angle working face,the spontaneous combustion of the residual coal in the goaf is relatively hidden,which makes it difficult to prevent and control the spontaneous combustion.At the same time,the residual coal in the large dip Angle goaf is in different pressure states and breaking degrees,and the characteristics of the coal’s compressive breaking are not clear.In combination with the difficulty and low accuracy of the monitoring of the residual coal ’s spontaneous combustion in the large dip Angle goaf,the related theories and experimental results are not accurate enough to describe the related problems.Therefore,it is necessary to carry out experimental research on the characteristics of pressure crushing and spontaneous combustion of residual coal in goaf with large dip Angle,to determine the spontaneous combustion law of residual coal in goaf with large dip Angle,and to provide theoretical support for the prevention and control of spontaneous combustion of residual coal with large dip Angle.Based on this,the numerical simulation study on the stress distribution characteristics of the goaf in the large dip Angle working face was carried out,and the experimental study on the characteristics of pressure crushing was carried out,and then the experimental study on the spontaneous combustion of the coal under pressure crushing and the residual coal in the similar goaf was carried out.Finally,the temperature rising law of the residual coal spontaneous combustion and the distribution characteristics of the spontaneous combustion risk area were determined.The results show that:the average compression ratio of 10-20 mm lumber coal is 17%-40%,the crushing coefficient of lumber coal is 2.15-1.34,the average crushing ratio of lumber coal is 69.5%-86.6%under the condition of vertical stress 2.76-22.06 MPa,and the mass ratio of four ends after crushing is significantly negatively correlated with the load,there is a significant positive correlation between the mass ratio below the particle size and the load.In the process of physical heating and heating in nitrogen environment,the coal sample temperature is divided by 100℃ with the furnace temperature(air flow temperature),which has a nonlinear growth law of quadratic function first and then cubic function.Nitrogen flow rate has a significant influence on the distribution of temperature in the coal sample.In the air environment,there is an exponential function relationship between the oxygen consumption rate,CO production rate,exothermic intensity of the crushed coal and the mass ratio of crushed particle size during the oxidation process of the residual coal.Under different air leakage conditions,the oxidation temperature of coal samples also has significant spatial location difference characteristics.The apparent activation energy of coal in the stage of 40-70℃ at air volume of 120-1000 mL/min is 20.13 kJ/mol,23.29 kJ/mol,14.57 kJ/mol,8.92 kJ/mol and 19.29 kJ/mol,respectively.Based on five hypotheses to determine the adiabatic oxidation characteristics of coal conducting rapid temperatures-programmed experiments in nitrogen and air atmospheres,a method was proposed to calculate the temperature rise of adiabatic oxidation and exothermic oxidation based on the temperature difference between air and nitrogen subtracting the temperature rise of oxidation and exothermic oxidation corresponding to nitrogen atmospheres.The calculated adiabatic spontaneous combustion periods under the air volume of 250 mL/min,500 mL/min and 1000 mL/min are respectively 626.3 h,274.4 h and 180.1 h.A similar experimental system for spontaneous combustion of residual coal in goaf based on programmed heating was designed and constructed at a ratio of 1:200.The system mainly includes four subsystems:gas supply system,similar goaf and programmed heating system,negative pressure ventilation system,and temperature monitoring and acquisition system.Through different Angle respectively with nitrogen,but the law of residual coal to heat up the air environment comparison found:large tilt Angle face goaf return air side,compared with the level of working face in return air side is more easy to spontaneous combustion,and in the field and cut the top line of spontaneous combustion risk bigger parts of the area of working face length,1/6-1/2 and open cut on the corner of the eye is the most significant.In addition,compared with the horizontal working face,the tendency center area from the top cutting line to the deep 1/6-1/3 of the goaf and the shallow area are more likely to heat up due to oxidation.At the same time,except for the inlet side(inclined lower)under the condition of large dip Angle working face,the risk of spontaneous combustion is similar to that of the horizontal working face in a small part near the 1/6 working face length of the top cut line,other deep areas of goaf are all difficult spontaneous combustion areas.This thesis has 123 figures,54 tables and 112 references.更多还原