Abstract:
The burning behaviors of pulverized coal under different atmospheres (O
2/N
2, O
2/CO
2 and O
2/H
2O/CO
2) in the range of temperature (800-1 200 ℃) and oxygen concentration (2%-21%) were comparatively investigated using the isothermal thermal analysis system.The combustion characteristics of coal samples under the action of CO
2/H
2O gasification were mainly studied.The results indicate that at 800 ℃ the burning rate of Datong bituminous coal (DT) in O
2/N
2 is faster than that in O
2/CO
2 due to the different physical properties between N
2 and CO
2.The effect of CO
2 gasification is enhanced with the increase of temperature from 1 000 ℃ to 1 200 ℃ and as a result, the overall reaction rate of DT in O
2/CO
2 approaches and exceeds the burning rate in O
2/N
2.But the effect of gasification is weakened with the increase of oxygen concentration (e.g.≥10%), and the reaction rate of DT in O
2/CO
2 gradually lags behind that in O
2/N
2.Because the specific heat and the oxygen diffusion rate of H
2O are between those of N
2 and CO
2, the combustion rate of DT in the O
2/CO
2/H
2O is lower than that in O
2/N
2 but higher than that in O
2/CO
2 without the effect of gasification.At 2% oxygen concentration, the influence of CO
2 and H
2O synergistic gasification is enhanced by increasing temperature and thus the overall reaction rate in the O
2/H
2O/CO
2 is always higher than that in O
2/CO
2.But a higher oxygen concentration (e.g.10%) weakens the effect of synergistic gasification which leads to the similar burning processes in different atmospheres.With the effect of gasification, the overall reaction rate of Yangquan anthracite (YQ) increases more significantly compared to DT, which indicates that the gasification has remarkable influences on the reaction process of high-rank coal.
下载: