【摘要】：煤的自燃氧化是一個復雜的動力學過程,深入分析與掌握煤氧化的動力學規(guī)律,對研究煤自然著火有著非常重要的意義。以三種低階煤為研究對象,兩種高階煤為對比煤樣,選用Redfern-Coats積分方程對煤自燃最概然機理函數進行推斷,得出了低階煤在失水脫附階段屬于一級化學反應,吸氧增重階段屬于三維擴散機理函數。經過計算發(fā)現,低階煤的活化能低于高階煤種,而且隨著溫度的升高,反應程度加深,活化能增大,指前因子也隨之增加。通過對煤樣的產熱速率進行分析發(fā)現,煤的低溫氧化都經歷了吸熱然后再放熱的過程,產熱速率隨溫度的升高而增加,低階煤的初始放熱溫度較低,而總放熱量卻高于高階煤種。利用程序升溫氧化系統(tǒng)和傅里葉紅外光譜儀,通過對煤氧化過程中的氣體產物和官能團的變化情況的分析發(fā)現,在氧化過程中最先出現的是CO氣體,緩慢氧化階段CO氣體產量較少,曲線平緩。隨著溫度的升高氣體產量逐漸增加,烴類氣體也逐漸產生。低階煤分子結構中的脂肪烴和含氧官能團含量明顯大于變質程度高的煤,而且這兩種基團活性較高,在氧化過程中變化明顯。經研究推斷出CO直接來源于醛基,而烴類氣體主要是由脂肪鏈的斷裂產生。低階煤結構復雜,穩(wěn)定性差,在反應過程中易于分解,生成大量氣體,自燃危險性較大。煤的氧化是多步反應,不同步驟之間相互競爭又相互聯(lián)系,反應速率隨溫度升高逐漸加快,參與反應的分子數量也隨之增加。
[Abstract]:The spontaneous combustion oxidation of coal is a complicated dynamic process. It is very important to analyze and master the kinetic law of coal oxidation. Taking three kinds of low-rank coal as the research object and two kinds of high-order coal as contrast coal samples, the Redfern-Coats integral equation is used to infer the most probable mechanism function of coal spontaneous combustion, and it is concluded that the low-rank coal is a first-order chemical reaction in the desorption stage of water loss. The phase of oxygen absorption and weight gain belongs to three dimensional diffusion mechanism function. The results show that the activation energy of low-rank coal is lower than that of high-order coal, and with the increase of temperature, the degree of reaction deepens, the activation energy increases and the pre-exponential factor increases. Through the analysis of the heat production rate of coal samples, it is found that the low temperature oxidation of coal goes through the process of endothermic and then exothermic, the heat production rate increases with the increase of temperature, and the initial exothermic temperature of low rank coal is lower. However, the total heat release is higher than that of high-order coal. By using the temperature programmed oxidation system and Fourier transform infrared spectrometer, it is found that CO gas is the first one to appear in the oxidation process by analyzing the changes of gas products and functional groups in the process of coal oxidation. At the stage of slow oxidation, CO gas production is less and the curve is smooth. With the increase of temperature, the production of hydrocarbon gas increases gradually. The content of aliphatic hydrocarbons and oxygen-containing functional groups in the molecular structure of low-rank coal is obviously higher than that in high-grade metamorphic coal, and the activity of these two groups is higher, and the changes are obvious during the oxidation process. It is inferred that CO is directly derived from aldehyde group, while hydrocarbon gas is mainly produced by the breakage of fatty chain. The structure of low rank coal is complex, the stability is poor, it is easy to decompose in the reaction process, produce a large amount of gas, and the danger of spontaneous combustion is great. The oxidation of coal is a multi-step reaction. The reaction rate increases with the increase of temperature and the number of molecules participating in the reaction increases.
【學位授予單位】：華北理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD752.2

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相關期刊論文 前10條

1 魏琰榮;肖翠微;王乃繼;王永英;;補連塔煤低溫氧化特性的熱重研究[J];潔凈煤技術;2016年01期

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本文編號：2149549