【摘要】：科學(xué)鑒定煤的自燃傾向性對礦井的防滅火工作和煤炭的安全開采具有非常重要的意義,但是由于煤體自身及其自燃過程的復(fù)雜性,國內(nèi)外至今還沒有統(tǒng)一的鑒定方法與指標(biāo)。本文分析了目前主要的鑒定方法,指出了各種方法的局限性和存在的不足。在對煤自燃機(jī)理、自燃過程及表現(xiàn)特性進(jìn)行研究的基礎(chǔ)上,得出以煤低溫氧化表觀活化能為鑒定指標(biāo)的可行性。為了使煤低溫氧化表觀活化能指標(biāo)能夠有效地應(yīng)用于煤自燃傾向性鑒定的研究中,使用差示掃描量熱儀對不同煤樣進(jìn)行了煤自燃傾向性的實(shí)驗(yàn)研究。不同粒度煤樣的DSC曲線表明,隨著煤樣粒度的減小,DSC曲線向低溫方向移動(dòng),煤樣的放熱速率加快,煤樣著火提前。通過DSC動(dòng)力學(xué)法計(jì)算得到煤低溫氧化表觀活化能,表明表觀活化能隨煤樣粒度的減小而減小,即煤樣粒度越小,越容易著火,自燃傾向性越大。通過3種不同粒度煤樣計(jì)算的低溫氧化活化能與現(xiàn)場煤自然發(fā)火期進(jìn)行對比,發(fā)現(xiàn)煤樣粒度為100-150目時(shí)計(jì)算的活化能與煤樣實(shí)際自燃情況相關(guān)性最好,表明100-150目可作為研究煤自燃傾向性的合適粒度。與此同時(shí),通過對相同煤樣的物理吸氧量進(jìn)行測試,并與現(xiàn)場煤自然發(fā)火期進(jìn)行對比,發(fā)現(xiàn)線性相關(guān)性并不好,這表明煤低溫氧化表觀活化能比煤物理吸氧量更能反映煤自燃的難易程度,即更能反映煤的自燃傾向性。不同升溫速率的煤樣DSC曲線表明,升溫速率越大,單位時(shí)間內(nèi)煤樣產(chǎn)生的熱效應(yīng)越大,峰高越高,峰值溫度也越高,這導(dǎo)致分辨率下降而靈敏度提高;反之,升溫速率越小,則峰值越低,測試的分辨率越好而靈敏度降低。因此,升溫速率是對DSC曲線產(chǎn)生明顯影響的實(shí)驗(yàn)條件之一,實(shí)驗(yàn)時(shí)要選擇合適的升溫速率,提高煤低溫氧化活化能計(jì)算結(jié)果的準(zhǔn)確性,使煤自燃傾向性的鑒定結(jié)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.
【學(xué)位授予單位】：華北科技學(xué)院
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TD752.2

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