随机孔模型应用于煤焦与CO_2气化的动力学研究

Kinetics of coal char gasification with CO_2 Random pore model

考察970 ℃～1 165 ℃,北宿、神府、忻州、潞安煤焦与CO2在热天平中的气化反应,用恒温法进行热重分析,考察煤种、气化温度、灰分对煤焦气化的影响.用随机孔模型模拟北宿煤反应速率与碳转化率的关系曲线,与未反应芯缩核模型和混合模型模拟结果比较.在化学控制区内,实验数据用随机孔模型拟合最佳.1 066 ℃和1 165 ℃气化数据拟合的相关系数为0.99,970 ℃拟合效果较差.随机孔模型作为简单、精度高的模型可应用于煤炭气化反应中.应用此模型计算四种煤焦反应活化能、指前因子、孔结构参数、A0等动力学参数值.同一煤种气化反应温度越高初始反应速率越大,结构参数体现了孔结构变化对反应的影响,随着温度的升高值减小.

The gasification of Beisu, Shenfu, Xinzhou and Luan coal chars with CO2 at 970 ℃ ～ 1 165 ℃ was studied by the isothermal thermogravimetric analysis （TGA） under the condition of chemical reaction control. The effects of coal types, temperature and ash content in coal on the char gasification with CO2 were examined. The random pore model, the unreacted shrinking core reaction model and the integrated model were tested by the experimental data respectively. The results show that the random pore model is the best to fit the experiment data among three kinetic models, which has a correlation coefficients of 0.99 both at 1 066 ℃ and 1 165 ℃. The kinetic parameters （ E, k0, A0, ψ ） are obtained. A0 is bigger when the gasification temperature is higher. ψ as the initial pore structure parameter is affected by the change of pore structure at different pyrolysis temperatures. It becomes smaller when the gasification temperature increases.