Thermal Behavior of Coal Used in Rotary Kiln and Its Combustion Intensification

Qiang Zhong, Jian Zhang, Yongbin Yang, Qian Li, Bin Xu and Tao Jiang
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Qiang Zhong: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Jian Zhang: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Yongbin Yang: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Qian Li: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Bin Xu: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Tao Jiang: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China

Energies, 2018, vol. 11, issue 5, 1-12

Abstract: Pyrolysis and combustion behaviors of three coals (A, B, and C coals) were investigated and their combustion kinetics were calculated by the Freeman–Carroll method to obtain quantitative insight into their combustion behaviors. Moreover, the effects of coal size, air flow, oxygen content, and heating rate on coal combustion behaviors were analyzed. Results showed that the three coals have a similar trend of pyrolysis that occurs at about 670 K and this process continuously proceeds along with their combustion. Combustion characteristics and kinetic parameters can be applied to analyze coal combustion behaviors. Three coals having combustion characteristics of suitable ignition temperature (745–761 K), DTG max (14.20–15.72%/min), and burnout time (7.45–8.10 min) were analyzed in a rotary kiln. Combustion kinetic parameters provide quantitative insights into coal combustion behavior. The suitable particle size for coal combustion in a kiln is that the content of less than 74 μm is 60% to 80%. Low activation energy and reaction order make coal, especially C coal, have a simple combustion mechanism, great reactivity, be easily ignited, and a low peak temperature in the combustion state. Oxygen-enrichment and high heating rates enhance coal combustion, increasing combustion intensity and peak value, thus shortening burnout time.

Keywords: thermal behavior; coal; rotary kiln; thermogravimetric analysis; combustion intensification (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
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