Influencing factors and mechanisms involved in the ignition of low-rank coal: Implications for spontaneous combustion

¹ MOE Key Laboratory of Resources and Environmental System Optimization, School of Environmental Science and Engineering, North China Electric Power University, 102206, Beijing, China
² New Energy Research Center, National Institute of Clean-and-Low-Carbon Energy, 102211, Beijing, China
³ Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Institute of Coal Chemical Engineering, Taiyuan University of Technology, 030024, Shanxi, China

^* Corresponding author: zhangyueling@ncepu.edu.cn

Abstract

Understanding the ignition mechanism of spontaneous combustion is critical for preventing it. In this work, the effects of different test conditions including oxygen concentration, heating rate, oxidation carrier gas flow rate, and sample amount on the ignition temperature were studied with a thermal gravimetric analyzer. Further, the effects of coal properties on the ignition temperature were also investigated using 15 different low-rank coals. A heterogenous ignition model was proposed that small amount of active species is the key material leading to ignition. The heterogenous ignition mechanism well explained the complex effects of test conditions and coal properties on the ignition temperature of low-rank coal. Finally, an empirical formula for predicting the ignition temperature was derived for the rapid assessment of the spontaneous combustion potential.