Experimental investigation of pressurized combustion characteristics of single coal particle in O2/N2 and O2/CO2 environments

Pressurized oxy-fuel combustion has been developed as a clean technology to realize higher efficiency and lower CO2 emissions. The combustion characteristics of a pulverized bituminous coal were investigated in a high-pressure optical accessible flat-flame reactor. The experiments were conducted in O2/N2 and O2/CO2 environments. The tests were conducted at a gas temperature of 1400 K, under pressures ranging from 0.1-0.5 MPa and at an oxygen concentration of 20%. An image processing technology was applied to investigate the processes of ignition, devolatilization and burnout. The temperatures and diameters of individual burning particles were optically measured by a high-speed camera in conjunction with a long-distance microscope. A 532-nm continuous laser was used to trace the unburnt particles. The optical measurements were used to analyze the apparent kinetics of char oxidation using a commonly employed single-film burnout model. The results indicate that an increase in pressure causes a longer ignitio...