Abstract:

TG-DTG and DTA determination indicated that ignition temperature of anthracite was lowered from 458℃ to 405℃ by addition of 10% catalyst Fe₂O₃.Based on the nature of anthracite ignition temperature, pyrolysis conversion and pyrolysis gas composition during the catalytic combustion were examined.The results showed that with Fe₂O₃ addition anthracite pyrolysis conversion was 3.0% at 405℃ and components with higher heating value increased in the pyrolysis gas. However, without Fe₂O₃ addition pyrolysis conversion was 1.8% at ignition temperature.It could be concluded that the heat from the homogeneous combustion of catalytic combustion was higher than that of non-catalytic combustion.TG-DTG indicated combustion conversion of 10 % at ignition.SEM images of chars indicated rough surface of char with plenty of small pores.BET of char from catalytic combustion was 170 m²•g^-1 while BET of char from non-catalytic combustion was only 128 m²•g^-1, which could be the main reason for lowering ignition temperature.The results from oxygen adsorption experiment showed increased oxygen content of coal with catalyst addition, which caused faster oxygen adsorption at a lower temperature and shortened the time to get required oxygen concentration and heat accumulation for ignition, thus the ignition temperature was lowered.

摘要： 利用TG-DTG法和DTA法研究了无烟煤催化燃烧时燃点的变化情况，结果表明Fe2O3可使无烟煤的燃点降低。基于无烟煤燃点的形成原因和催化热解过程，研究了催化热解过程中热解转化率、热解气组成、半焦表面结构的变化情况，结果表明Fe2O3促进了无烟煤的热解，热解转化率、热解气的组成明显变化，热解气热值增加。催化热解产生的半焦表面形貌粗糙，颗粒细碎，比表面积大。由于热解过程直接影响到点燃过程，因此通过催化热解的研究，可知催化燃烧过程中均相燃烧（热解气燃烧）提供给异相燃烧（半焦燃烧）的热量高于非催化燃烧。同时催化热解所得半焦的吸附氧气能力强，在低温时吸附氧气的速率较快，缩短了达到点燃时所需氧气浓度的时间，进而降低了无烟煤的燃点。