Competition and Inhibition Effects during Coal Char Gasification in the Mixture of H2O and CO2

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• 作者：Rui Zhang ; Qin H. Wang ; Zhong Y. Luo ; Meng X. Fang ; Ke F. Cen
• 刊名：Energy & Fuels
• 出版年：2013
• 出版时间：September 19, 2013
• 年：2013
• 卷：27
• 期：9
• 页码：5107-5115
• 全文大小：443K
• 年卷期：v.27,no.9(September 19, 2013)
• ISSN：1520-5029

文摘

The mechanisms of char gasification in the mixture of H₂O and CO₂ are not clear, and some problems are yet to be solved. The Langmuir鈥揌inshelwood (L鈥揌) model of char gasification in the mixture of H₂O and CO₂ and the inhibition effect between char鈥揌₂O and char鈥揅O₂ reactions are two controversial issues among these problems. This paper presented new data to elucidate these two issues. Experiments were carried out at atmospheric pressure using a modified thermogravimetric analyzer (TGA) system at various reactant partial pressures and within a temperature range of 1173鈥?273 K. The kinetic parameters in the L鈥揌 model were determined from pure H₂O and CO₂ gasification (N₂ as a diluent). The experimental results showed that the L鈥揌 model based on common active site assumption is applicable to describe the experimental data and the pressure is not the reason leading to different results in validity experiments of common or separate active site assumptions. Including H₂ and CO in the reactant gas does not change the reaction mechanisms from common active sites to separate active sites either. It was also found that the reaction rate first decreases and then increases as the CO₂ concentration increases at a fixed H₂O concentration, while the reaction rate continuously increases as the H₂O concentration increases at a fixed CO₂ concentration. This means that the char鈥揌₂O reaction is inhibited by the char鈥揅O₂ reaction. Finally, the specific surface area tests of char samples at 20% carbon conversion confirm the common active site assumption.