Abstract:
The burning behaviors of Datong coal and char under O
2/N
2, O
2/CO
2 and O
2/H
2O/CO
2 atmosphere were comparatively investigated by thermogravimetric analyzer. The influence of CO
2 and H
2O gasification on the oxy-fuel combustion characteristics of coal and char were mainly studied. The results indicate that at 5% oxygen concentration the burning rate of pulverized coal in each atmosphere decreases in the order of O
2/N
2, O
2/CO
2 and O
2/H
2O/CO
2. When the oxygen concentration reduces to 2%, owing to the CO
2 and H
2O gasification, the overall reaction rate of pulverized coal increases in the same order at high temperatures. The burning rate of char is slower in O
2/CO
2 than that in O
2/N
2 at 5% oxygen concentration, but as the burning process is delayed, the overall reaction rate of char in O
2/H
2O/CO
2 rises significantly due to the action of gasification. At 2% oxygen concentration, the overall reaction rate of char in O
2/CO
2 is higher than the burning rate of char in O
2/N
2 with the rise in temperature. The overall reaction rate of char in O
2/H
2O/CO
2 further increases because the H
2O gasification plays a major role in CO
2 and H
2O co-gasification. The kinetic analysis shows that at 5% oxygen concentration the apparent activation energy in the atmosphere increases in the order of O
2/N
2, O
2/CO
2 and O
2/H
2O/CO
2. However, the apparent activation energy of different atmospheres declines with the decrease of oxygen concentration.
下载: