Pyrolysis and combustion behaviors of three coals (A, B, and C coals) were investigated\nand their combustion kinetics were calculated by the Freemanââ?¬â??Carroll method to obtain quantitative\ninsight into their combustion behaviors. Moreover, the effects of coal size, air flow, oxygen content,\nand heating rate on coal combustion behaviors were analyzed. Results showed that the three coals\nhave a similar trend of pyrolysis that occurs at about 670 K and this process continuously proceeds\nalong with their combustion. Combustion characteristics and kinetic parameters can be applied\nto analyze coal combustion behaviors. Three coals having combustion characteristics of suitable\nignition temperature (745ââ?¬â??761 K), DTGmax (14.20ââ?¬â??15.72%/min), and burnout time (7.45ââ?¬â??8.10 min)\nwere analyzed in a rotary kiln. Combustion kinetic parameters provide quantitative insights into coal\ncombustion behavior. The suitable particle size for coal combustion in a kiln is that the content of less\nthan 74 Ã?¼mis 60% to 80%. Low activation energy and reaction order make coal, especially C coal, have\na simple combustion mechanism, great reactivity, be easily ignited, and a low peak temperature in the\ncombustion state. Oxygen-enrichment and high heating rates enhance coal combustion, increasing\ncombustion intensity and peak value, thus shortening burnout time.
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