Study on Combustion Characteristic of Coal-Char in Oxygen-Enriched Environments

Oxygen-enriched (O₂/CO₂) combustion in circulating fluidized bed(CFB) is one of the most promising clean coal combustion technology which shows good gaseous pollutants control, especially greenhouse CO₂. In the paper, the thermogravimetric experiments of Hennan lean coal-char under O₂/CO₂ and O₂/N₂ atmosphere have been carried out, the influence of atmosphere, O₂ concentration and heating rate on the combustion characteristic of coal-char being analysed. The results of the experiment show that O₂ concentration and heating rate have a great influence on the coal-char combustion characteristics in oxygen-enriched environment. The coal-char combustion characteristic ameliorates with increasing the O₂ concentration and improving the heating rate. Under the same O₂ concentration, the coal-char combustion characteristic in O₂/CO₂ atmosphere is a little poorer than that in O₂/N₂ atmosphere. A reaction kinetic model for coal-char combustion in oxygen-enriched environment was also deduced and it agreed well with experimental data.