Combustion rates of pulverized coal particles in high-temperature/high-oxygen concentration atmosphere

Abstract Combustion characteristics of pulverized coal particles at particle temperatures over 1800°C and oxygen concentration of 40%–80% were investigated using a high-temperature drop furnace. The results demonstrate that the ignition delay time and burnout time are less than 10 and 50 ms, respectively, in the case of combustion under a high-temperature/high-oxygen concentration atmosphere. It was found that the char combustion rate was controlled by gas film diffusion, and the apparent activation energy was about 8.4 kJ/mol. Also, the rotation of pulverized coal particles was observed during early-stage of combustion and the rotation frequency reached 3000–5000 cycles/s. The combustion rate of volatile matter was remarkably increased within the range of particle temperature over 2100°C. The apparent activation energy of the combustion rate of volatile matter was increased with increasing particle temperature and oxygen concentration. The value of activation energy changed from 109.2 kJ/mol for particle temperature 1800–2100°C and oxygen concentration 40%–50% to 336 kJ/mol for particle temperature over 2500°C and oxygen concentration 70%–80%.