基于DSC的煤自燃倾向性鉴定实验研究
发布时间：2018-08-20 12:01
【摘要】：科学鉴定煤的自燃倾向性对矿井的防灭火工作和煤炭的安全开采具有非常重要的意义,但是由于煤体自身及其自燃过程的复杂性,国内外至今还没有统一的鉴定方法与指标。本文分析了目前主要的鉴定方法,指出了各种方法的局限性和存在的不足。在对煤自燃机理、自燃过程及表现特性进行研究的基础上,得出以煤低温氧化表观活化能为鉴定指标的可行性。为了使煤低温氧化表观活化能指标能够有效地应用于煤自燃倾向性鉴定的研究中,使用差示扫描量热仪对不同煤样进行了煤自燃倾向性的实验研究。不同粒度煤样的DSC曲线表明,随着煤样粒度的减小,DSC曲线向低温方向移动,煤样的放热速率加快,煤样着火提前。通过DSC动力学法计算得到煤低温氧化表观活化能,表明表观活化能随煤样粒度的减小而减小,即煤样粒度越小,越容易着火,自燃倾向性越大。通过3种不同粒度煤样计算的低温氧化活化能与现场煤自然发火期进行对比,发现煤样粒度为100-150目时计算的活化能与煤样实际自燃情况相关性最好,表明100-150目可作为研究煤自燃倾向性的合适粒度。与此同时,通过对相同煤样的物理吸氧量进行测试,并与现场煤自然发火期进行对比,发现线性相关性并不好,这表明煤低温氧化表观活化能比煤物理吸氧量更能反映煤自燃的难易程度,即更能反映煤的自燃倾向性。不同升温速率的煤样DSC曲线表明,升温速率越大,单位时间内煤样产生的热效应越大,峰高越高,峰值温度也越高,这导致分辨率下降而灵敏度提高;反之,升温速率越小,则峰值越低,测试的分辨率越好而灵敏度降低。因此,升温速率是对DSC曲线产生明显影响的实验条件之一,实验时要选择合适的升温速率,提高煤低温氧化活化能计算结果的准确性,使煤自燃倾向性的鉴定结果合理有效。
[Abstract]:It is very important to scientifically identify the tendency of spontaneous combustion of coal to prevent and extinguish fire in mines and to exploit coal safely. However, because of the complexity of coal body itself and the process of spontaneous combustion, there is no unified appraisal method and index at home and abroad. In this paper, the main identification methods are analyzed, and the limitations and shortcomings of these methods are pointed out. Based on the study of coal spontaneous combustion mechanism, spontaneous combustion process and performance characteristics, the feasibility of using the apparent activation energy of coal oxidation at low temperature as the identification index is obtained. In order to make the apparent activation energy index of coal oxidation at low temperature can be used effectively in the study of coal spontaneous combustion tendency, the experimental study on coal spontaneous combustion tendency of different coal samples was carried out by using differential scanning calorimeter (DSC). The DSC curves of coal samples with different particle sizes show that with the decrease of coal particle size and the shift of the curve to low temperature, the exothermic rate of coal samples is accelerated, and the ignition of coal samples is advanced. The apparent activation energy of coal oxidation at low temperature was calculated by DSC kinetic method. It shows that the apparent activation energy decreases with the decrease of coal particle size, that is, the smaller the coal particle size, the easier to catch fire, and the greater the tendency of spontaneous combustion. The low temperature oxidation activation energy calculated by three kinds of coal samples with different particle sizes is compared with the spontaneous combustion period of coal in situ. It is found that the calculated activation energy of coal samples with 100-150 mesh size has the best correlation with the actual spontaneous combustion of coal samples. It is shown that 100-150 mesh can be used as an appropriate particle size for the study of coal spontaneous combustion tendency. At the same time, by testing the physical oxygen uptake of the same coal sample and comparing it with the spontaneous combustion period of the coal in the field, it is found that the linear correlation is not good. This indicates that the apparent activation energy of coal oxidation at low temperature can reflect the degree of difficulty and ease of spontaneous combustion of coal more than the physical oxygen absorption of coal, that is, it can reflect the tendency of spontaneous combustion of coal more effectively. The DSC curves of coal samples with different heating rates show that the higher the heating rate, the greater the thermal effect, the higher the peak height and the higher the peak temperature, which leads to the decrease of resolution and the improvement of sensitivity, whereas, the smaller the heating rate is, the lower the heating rate is. The lower the peak value, the better the resolution of the test and the lower the sensitivity. Therefore, the heating rate is one of the experimental conditions which has obvious influence on the DSC curve. In order to improve the accuracy of the calculation results of the activation energy of coal oxidation at low temperature, it is necessary to select the appropriate heating rate during the experiment, so as to make the evaluation results of coal spontaneous combustion tendency reasonable and effective.
【学位授予单位】：华北科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD752.2
[Abstract]:It is very important to scientifically identify the tendency of spontaneous combustion of coal to prevent and extinguish fire in mines and to exploit coal safely. However, because of the complexity of coal body itself and the process of spontaneous combustion, there is no unified appraisal method and index at home and abroad. In this paper, the main identification methods are analyzed, and the limitations and shortcomings of these methods are pointed out. Based on the study of coal spontaneous combustion mechanism, spontaneous combustion process and performance characteristics, the feasibility of using the apparent activation energy of coal oxidation at low temperature as the identification index is obtained. In order to make the apparent activation energy index of coal oxidation at low temperature can be used effectively in the study of coal spontaneous combustion tendency, the experimental study on coal spontaneous combustion tendency of different coal samples was carried out by using differential scanning calorimeter (DSC). The DSC curves of coal samples with different particle sizes show that with the decrease of coal particle size and the shift of the curve to low temperature, the exothermic rate of coal samples is accelerated, and the ignition of coal samples is advanced. The apparent activation energy of coal oxidation at low temperature was calculated by DSC kinetic method. It shows that the apparent activation energy decreases with the decrease of coal particle size, that is, the smaller the coal particle size, the easier to catch fire, and the greater the tendency of spontaneous combustion. The low temperature oxidation activation energy calculated by three kinds of coal samples with different particle sizes is compared with the spontaneous combustion period of coal in situ. It is found that the calculated activation energy of coal samples with 100-150 mesh size has the best correlation with the actual spontaneous combustion of coal samples. It is shown that 100-150 mesh can be used as an appropriate particle size for the study of coal spontaneous combustion tendency. At the same time, by testing the physical oxygen uptake of the same coal sample and comparing it with the spontaneous combustion period of the coal in the field, it is found that the linear correlation is not good. This indicates that the apparent activation energy of coal oxidation at low temperature can reflect the degree of difficulty and ease of spontaneous combustion of coal more than the physical oxygen absorption of coal, that is, it can reflect the tendency of spontaneous combustion of coal more effectively. The DSC curves of coal samples with different heating rates show that the higher the heating rate, the greater the thermal effect, the higher the peak height and the higher the peak temperature, which leads to the decrease of resolution and the improvement of sensitivity, whereas, the smaller the heating rate is, the lower the heating rate is. The lower the peak value, the better the resolution of the test and the lower the sensitivity. Therefore, the heating rate is one of the experimental conditions which has obvious influence on the DSC curve. In order to improve the accuracy of the calculation results of the activation energy of coal oxidation at low temperature, it is necessary to select the appropriate heating rate during the experiment, so as to make the evaluation results of coal spontaneous combustion tendency reasonable and effective.
【学位授予单位】：华北科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD752.2
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