比表面积和灰分对烟煤半焦气化机理的影响

Effect of Specific Surface Area and Ash Content on the Mechanisms of Bituminous Coal Char Gasification

Langmuir-Hinshelwood(L-H)动力学模型在描述H2O与CO2混合气氛下的煤焦气化时,存在公共活性位与单独活性位2种矛盾的反应机理假设。为解释这一矛盾现象,提出了比表面积和灰分2种可能的因素。实验在改造后的热重分析仪上进行,实验系统压力为常压,反应温度为1223K。实验结果表明,比表面积和灰分均会对煤焦气化机理产生影响。比表面积较大的煤焦,其实验结果更符合基于单独活性位假设的L-H模型预测值,而比表面积较小的煤焦,其实验结果与基于公共活性位假设的L-H模型预测值相吻合。脱灰后的煤焦,其实验结果与基于2种假设的L-H模型预测值均不吻合。

Two different controversial assumptions, common or separate active sites assumptions, existed in the Langrnuir-Hinshelwood （L-H） kinetic model when coal char gasified by the mixture of H20 and CO2. This paper proposed two potential factors, specific surface area and ash content, to elucidate the reason for this controversial issue. Experiments were conducted at atmospheric condition and a temperature of 1223K, using a modified thermogravimetric analyzer （TGA） system at various reactant partial pressures. The experimental results showed that both specific surface area and ash content will affect the mechanisms of coal char gasification. The experimental data of coal char with large specific surface area fit the calculation of separate active sites assumption, while the experimental data of coal char with small specific surface area fit the calculation of another assumption very well. The experimental data of demineralized char didn＇t fit the calculation which based on both of these two active sites assumptions.