Mineral Transformation in Char and Its Effect on Coal Char Gasification Reactivity at High Temperatures Part 3: Carbon Thermal Reaction

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• 作者：Zhibin Ma ; Jin Bai ; Xiaodong Wen ; Xiaoming Li ; Yue Shi ; Zongqing Bai ; Lingxue Kong ; Zhenxing Guo ; Jingchong Yan ; Wen Li
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：May 15, 2014
• 年：2014
• 卷：28
• 期：5
• 页码：3066-3073
• 全文大小：530K
• 年卷期：v.28,no.5(May 15, 2014)
• ISSN：1520-5029

文摘

The reaction between mullite and carbon in char between 1200 and 1500 掳C during coal gasification was investigated by XRD, FactSage, and molecular simulation. The mechanism of thermal reaction is discussed by both thermal dynamic and molecular simulation methods. The effect of carbon thermal reaction on the char gasification was also discussed. The results show that the carbon thermal reaction between mullite and carbon in char only occurs in argon above 1300 掳C and the mullite could react with carbon completely to form moissanite (SiC) and corundum (Al₂O₃) at 1500 掳C in argon. This reaction is restrained by the existence of CO, and it occurs between 1300 and 1500 掳C when the partial pressure of CO in the atmosphere is less than 0.4 according to results of the thermodynamic calculation. In hence, carbon thermal reaction only happens in two following situations during gasification. One is the melted ash or slag over the surface of the char and the other is that the char particle is wholly covered by melted slag. The moissanite reacts with CO₂ to form SiO₂ and release CO during char gasification. The carbon thermal reaction between mullite and carbon in char facilitate the high-temperature coal gasification and could reduce the content of unreacted carbon in slag.