煤焦-CO_2高温气化反应特性的实验研究

利用STA409PC综合热分析仪以等温法研究煤焦-CO2高温气化反应,考察了煤种、气化温度及气流速度对煤焦气化反应的影响,并对其动力学参数进行了求算.实验结果表明:当气化温度低于煤焦灰熔点温度时,煤焦的碳转化率和反应速率峰值随气化温度的升高而增大,当气化温度高于煤焦的灰熔点温度时,煤焦的碳转化率和反应速率变化十分缓慢,甚至有下降的趋势;不同煤种的气化反应动力学参数有很大的差异,鞍钢煤焦和本钢煤焦的活化能均为140kJ/mol,阜新煤焦的活化能为70kJ/mol.当煤焦的气化反应温度高于煤焦的灰熔点温度时,扩散成为煤焦气化反应的主要限制环节,提高气流速度有利于煤焦气化反应的进行.

Experimental Study on Gasification Reaction Characteristics of Coal Char with CO_2 at Elevated Temperatures

The char-CO_2 gasification reactions at elevated temperature were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer.The effects of coal type,gasification temperature and gas flowrate on gasification reaction were investigated with relevant kinetic parameters calculated.The results showed that when the gasification temperature is lower than the fusion point of char ash,the coal char-CO_2 conversion rate and the peak value of reaction rate both increase with increasing gasification temperature.However,when the gasification temperature is higher than the fusion point,the carbon conversion and reaction rates both change so slowly even tend to decrease.The kinetic parameters on gasification reaction with different types of coal char used differ from each other,e.g.,the activation energy of coal char used in Ansteel and Bensteel is 140 kJ/mol,while that of the coal char from Fuxin is just 70kJ/mol.Then,the diffusion becomes the main bottleneck to the gasification reaction if the gasification temperature is higher than the fusion point of char ash.So,increasing the gas flowrate will benefit the char-CO_2 gasification reaction.